Author(s) ID,Title,Year,DOI,Link,Abstract
"57201570597;35621338300;7004958888;","Modelling of meteorological conditions at an urban scale for the PUMA winter campaign",2002,"10.1016/S1474-7065(02)00150-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036452281&doi=10.1016%2fS1474-7065%2802%2900150-X&partnerID=40&md5=fa2b316c667d89bbaa3a218193947e5f","For the winter 2000 campaign of the Pollution of Urban Midlands Atmosphere project, observation and numerical modelling of meteorological conditions over the West Midlands conurbation, UK, was undertaken. Modelling was performed using the regional atmospheric meteorological system (RAMS). This paper presents a comparison of modelled and observed wind and temperature for 25 and 26 January 2000. The RAMS model uses two nested grids with a mesh size of 2 km for the inner grid which is embedded in the outer grid with a mesh size of 8 km. Statistical evaluation of the model results against the observational data of wind speed, direction and temperature at 10 m was conducted. In general, the modelling results are in a reasonable agreement with observation. The statistical evaluation suggests that model performance is poorer for the inner grid than the outer grid as the model uncertainties (mainly mean bias) transfer from the outer to inner one. The low indices of agreement of temperature and wind are mainly associated with the systematic root-mean-square-difference values. For temperature, the systematic bias may also be affected by representation of cloud amount by the model. For wind, the model tends to have a poor performance for calm conditions, as under a stable anti-cyclonic situation local wind patterns associated with topography may develop, although the topography of the region is relatively flat. The results for the inner grid reveal some subtle spatial patterns at a scale smaller than 10 km near hills and valleys with differences in elevation of a few hundred metres. © 2002 Elsevier Science Ltd. All rights reserved."
"7003341789;6507964983;56499447000;7003849073;6603936414;35459699300;7405459515;","CRISTA observations of cirrus clouds around the tropopause",2002,"10.1029/2001JD000698","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1642331717&doi=10.1029%2f2001JD000698&partnerID=40&md5=efa231b7db5a5d583bf07945e6b0bca5","The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument observed thin cirrus clouds at and above the tropopause during its two missions in November 1994 and August 1997. A simple cloud detection scheme was developed for extinctions greater than 2× 10-3 km-1 through analysis of the measured infrared spectra in the 12-μm range. Horizontal and vertical distributions of cloud occurrence frequencies are in good agreement with the Stratospheric Aerosol and Gas Experiment (SAGE) II subvisual cirrus cloud (SVC) climatology as well as SAGE measurements for the 1997 period. Seasonal variations, strong longitudinal variability, and indications of enhanced cloud occurrence frequencies in separated regions caused by El Niño events were detected in the CRISTA data set. A substantial day-to-day variability could be found throughout the tropics, and several regions with enhanced variability have been identified. In addition, a significant amount of cloud was found above the midlatitude tropopause. Backward trajectories in relation to outgoing longwave radiation (OLR) measurements and cloud observation in the troposphere by meteorological satellites suggest that about three fourths of the high clouds (>15 km) observed by CRISTA in the tropics stem from deep convection systems and the outflow of these systems. This would imply that on the order of at least one fourth of the observed cloud events are originated by other mechanisms, such as in situ formation due to cooling events on synoptic and/or gravity wave scales. For the convective generated cirrus clouds, a maximum lifetime of around 3-4 days was estimated over a wide range of latitudes. Such a long lifetime could be important for modeling the impact of cirrus clouds on radiation budget (climate) and heterogeneous chemical processes around the tropopause. Copyright 2002 by the American Geophysical Union."
"55837471400;7101912085;","Simulating summertime rainfall variability in the North American monsoon region: The influence of convection and radiation parameterizations",2002,"10.1029/2001JD002047","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448945502&doi=10.1029%2f2001JD002047&partnerID=40&md5=1c4f7ca786b9a9122457e2ee15b64acb","Studying the dynamics of the North American Monsoon System (NAMS) is essential for understanding and assessing the predictability of its variability. Limited-area models are potentially useful tools for this endeavor, but it is important to first identify the suite of physical parameterizations that yields the most realistic simulations. We investigate how different convection and radiation schemes influence simulations of the NAMS produced with the MM5/OSU model. We focus on the simulated intraseasonal variability associated with monsoon onset (June to July) and changes between a wet (1999) and a dry (2000) year. We test six parameterizations, including two convection schema (Grell and Kain-Fritsch) and three radiation schema (CCM2, Cloud, and RRTM). We compare results from 2-month-long simulations to observations of circulation (NCEP Reanalysis) and rainfall (CPC and CMAP). Differences in simulated rainfall produced by the various combinations of schema are substantial, and much greater than the differences that arise from internal model variability in a three-member ensemble of Grell-RRTM simulations. The Grell-RRTM simulation produces the most realistic patterns and magnitudes of rainfall, including intraseasonal variations and the differences between the wet and dry year. Simulations using the Kain-Fritsch scheme produce too much rainfall, and fail to represent the atypical, observed decrease in precipitation from June-to-July in 2000. The CCM2 radiation scheme produces a simulated climate that is too cloudy, yielding little rainfall in the NAMS region regardless of the convection scheme used. The Cloud and RRTM radiation schemes allow for feedbacks between condensation and the water content of clouds, which yields substantial improvements in the model simulations. Copyright 2002 by the American Geophysical Union."
"55699179200;7202772927;35467186900;7006329926;","A study of the response of deep tropical clouds to large-scale thermodynamic forcings. Part I: Modeling strategies and simulations of TOGA COARE convective systems",2002,"10.1175/1520-0469(2002)059<3492:ASOTRO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037116331&doi=10.1175%2f1520-0469%282002%29059%3c3492%3aASOTRO%3e2.0.CO%3b2&partnerID=40&md5=c7764b36d459535166e3bc0ca44767d4","Interactions between deep tropical clouds over the western Pacific warm pool and the larger-scale environment are key to understanding climate change. Cloud models are an extremely useful tool in simulating and providing statistical information on heat and moisture transfer processes between cloud systems and the environment, and can therefore be utilized to substantially improve cloud parameterizations in climate models. In this paper, the Goddard Cumulus Ensemble (GCE) cloud-resolving model is used in multiday simulations of deep tropical convective activity over the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Large-scale temperature and moisture advective tendencies, and horizontal momentum from the TOGA COARE Intensive Flux Array region, are applied to the GCE version that incorporates cyclical boundary conditions. Sensitivity experiments show that the horizontal extent (size) of the domain produces the largest response to domain-mean temperature and moisture deviations, as well as cloudiness, in comparison with grid horizontal or vertical resolution, and advection scheme. It is found that a domain size of at least 512 km is needed to adequately contain the convective cloud features and to replicate both the eastward and westward movements of the observed precipitating systems. The control experiment shows that the atmospheric heating and moistening is primarily a response to cloud latent processes of condensation/evaporation, and deposition/ sublimation. Air-sea exchange of heat and moisture is found to be of secondary importance, while the net radiational heating-cooling is small except above cloud tops. A convective-stratiform breakdown of the precipitating systems shows that while 55% of the total rainfall occurs in convective regions, 90% of the total rainfall coverage occurs in stratiform regions. The simulated rainfall and atmospheric heating and moistening rates agree very well with observations, and the results compare favorably to other models simulating this case."
"7102731389;7403508241;7404150761;","Examination of new CERES data for evidence of tropical Iris feedback",2002,"10.1175/1520-0442(2002)015<3719:EONCDF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037116322&doi=10.1175%2f1520-0442%282002%29015%3c3719%3aEONCDF%3e2.0.CO%3b2&partnerID=40&md5=2110f5b28f92b3750a4d1d1dd92da1d9","New data products from the Clouds and the Earth's Radiant Energy System (CERES) instrument on the Tropical Rainfall Measuring Mission Satellite have been examined in the context of the recently proposed adaptive tropical infrared Iris hypothesis. The CERES Single Scanner Footprint data products combine radiative fluxes with cloud properties obtained from a co-orbiting imaging instrument. This enables the use of cloud property- based definitions of the various regions in the simple Iris climate model. Regardless of definition, the radiative properties are found to be different from those assigned in the original Iris hypothesis. As a result, the strength of the feedback effect is reduced by a factor of 10 or more. Contrary to the initial Iris hypothesis, most of the definitions tested in this paper result in a small positive feedback. Thus, the existence of an effective infrared iris to counter greenhouse warming is not supported by the CERES data."
"7005729142;6506385754;7103016965;7005890897;7003406689;7103400568;56216811200;7004399029;","Observations and parameterizations of particle size distributions in deep tropical cirrus and stratiform precipitating clouds: Results from in situ observations in TRMM field campaigns",2002,"10.1175/1520-0469(2002)059<3457:OAPOPS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037116314&doi=10.1175%2f1520-0469%282002%29059%3c3457%3aOAPOPS%3e2.0.CO%3b2&partnerID=40&md5=a4af9d97c61fa409de75991d1018062a","This study reports on the evolution of particle size distributions (PSDs) and habits as measured during slow, Lagrangian-type spiral descents through deep subtropical and tropical cloud layers in Florida, Brazil, and Kwajalein, Marshall Islands, most of which were precipitating. The objective of the flight patterns was to learn more about how the PSDs evolved in the vertical and to obtain information of the vertical structure of microphysical properties. New instrumentation yielding better information on the concentrations of particles in the size (D) range between 0.2 and 2 cm, as well as improved particle imagery, produced more comprehensive observations for tropical stratiform precipitation regions and anvils than have been available previously. Collocated radar observations provided additional information on the vertical structure of the cloud layers sampled. Most of the spirals began at cloud top, with temperatures (T) as low as -50°C, and ended at cloud base or below the melting layer (ML). The PSDs broadened from cloud top toward cloud base, with the largest particles increasing in size from several millimeters at cloud top, to 1 cm or larger toward cloud base. Some continued growth was noted in the upper part of the ML. Concentrations of particles less than 1 mm in size decreased with decreasing height. The result was a consistent change in the PSDs in the vertical. Similarly, systematic changes in the size dependence of the particle cross-sectional area was noted with decreasing height. Aggregation- as ascertained from both the changes in the PSDs and evolution of particle habits as observed in high detail with the cloud particle imager (CPI) probe-was responsible for these trends. The PSDs were generally well-represented by gamma distributions of the form N = N0rDμe-λrD that were fitted to the PSDs over 1-km horizontal intervals throughout the spirals. The intercept (N0r), slope (λr), and dispersion (μ) values were derived for each PSD. Exponential curves (N = N0e-λD; μ = 0) were also fitted to the distributions. The λr values for given spirals varied systematically with temperature as did the values of λ (exponential), and the data generally conformed to values found in previous studies involving exponential fits to size distributions in midlatitude frontal and cirrus layers. Considerable variability often noted in the PSD properties during the loops of individual spirals was manifested primarily in large changes in N0r and N0, but μ, λr, and λ remained fairly stable. Temperature is not found to be the sole factor controlling λr, or λ, but is a primary one. Direct relationships were found between λr and N0r and μ, for the gamma distributions, and λ and N0 for the exponential. The latter relationship was not found as distinctly in earlier studies: observed PSDs in this study had better fidelity with less scatter. The μ values changed monotonically with T over the range of temperatures and were directly related to N0r or λr, thereby reducing the number of variables in the PSD functional equation to two. In the upper part of the ML. N0 and λ continued to decrease, and in the lower part these values began to increase as the largest particles melted. General expressions relating various bulk microphysical, radar, and radiative-transfer-related variables to N0r and λr were developed: they are useful for both tropical and midlatitude clouds. These relationships facilitate the specification of a number of bulk properties in cloud and climate models. The results presented in this paper apply best to temperatures between 0° and -40°C, for which the measured radar reflectivities fall in the range of 0 to 25 dBZ."
"7102329065;7004114883;7202530955;","Differences between East and West Pacific rainfall systems",2002,"10.1175/1520-0442(2002)015<3659:DBEAWP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037116318&doi=10.1175%2f1520-0442%282002%29015%3c3659%3aDBEAWP%3e2.0.CO%3b2&partnerID=40&md5=4de466069c8ed83ea728d82e2df0e1cc","A comparison of the structure of precipitation systems between selected east and west Pacific regions along the intertropical convergence zone (ITCZ) is made using a combination of satellite observations including vertical profile retrievals from the Tropical Rainfall Measuring Mission's (TRMM's) Precipitation Radar. The comparison focuses on the period from December 1999 to February 2000, which was chosen due to large discrepancies in satellite infrared and passive microwave rainfall retrievals. Storm systems over the east Pacific exhibit a number of significant differences from those over the west Pacific warm pool including shallower clouds with warmer cloud tops, a larger proportion of stratiform rain, less ice for similar amounts of rainwater, and a radar bright band or melting layer significantly farther below the freezing level. These regional differences in the structure of precipitation systems between the east and west Pacific also exhibit seasonal and interannual variability. During the intense 1997/98 El Niño, warmer sea surface temperatures (SSTs) in the east Pacific led to precipitation systems with a very similar structure to those observed over the west. These differences in east versus west Pacific rainfall and changes associated with the El Niño-Southern Oscillation (ENSO) result in time-dependent regional biases in available long-term satellite precipitation datasets. Although all of the currently available infrared and passive microwave-based satellite retrievals exhibit similar spatial patterns and capture variability associated with ENSO, both the amplitude and sign of subtle climate signals, such as the response of tropical-mean rainfall to ENSO, depend on the retrieval algorithm used."
"36851768400;7201706787;55547129338;","Surface temperature of the Arctic: Comparison of TOVS satellite retrievals with surface observations",2002,"10.1175/1520-0442(2002)015<3698:STOTAC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037116291&doi=10.1175%2f1520-0442%282002%29015%3c3698%3aSTOTAC%3e2.0.CO%3b2&partnerID=40&md5=1f000a34228a91cc0571be56f91ecd91","Surface temperature is a fundamental parameter for climate research. Over the Arctic Ocean and neighboring seas conventional temperature observations are often of uncertain quality, however, owing to logistical obstacles in making measurements over sea ice in harsh environmental conditions. Satellites offer an attractive alternative, but standard methods encounter difficulty in detecting clouds in the frequent surface-based temperature inversion and when solar radiation is absent. The Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder Polar Pathfinder (TOVS Path-P) dataset provides nearly 20 yr (1979-98) of satellite-derived. gridded surface skin temperatures for the Arctic region north of 60°N. Another dataset based on surface observations has also recently become available. The International Arctic Buoy Program/Polar Exchange at the Sea Surface (IABP/POLES) project provides a gridded near-surface air temperature dataset based on optimally interpolated observations from Russian drifting ice stations, buoys, and land stations from 1979 to 1997. In this study these two datasets are compared and areas with large differences (4 to 6 K) are found in both winter and summer. Over the ice-covered Arctic Ocean in both seasons TOVS temperatures are substantially colder than POLES and over the Greenland-Iceland-Norwegian (GIN) Seas TOVS is warmer. Using point measurements from manned ice stations and ships it is found that POLES is too warm (∼ 2 K on average) in January. The bias is larger (∼ 4 K) in regions where the primary source of data is buoys, which contain warm biases in winter owing to the insulation effect of snow covering the sensors. The difference between skin and 2-m temperatures accounts for approximately 1 K of the January discrepancy between POLES and TOVS. Over the GIN Seas in both seasons POLES is much too cold (∼ 7 K) where values are based primarily on analyses from the National Centers for Environmental Prediction (NCEP). In July the TOVS temperatures are approximately 6 K too cold over ice-covered regions owing to poor retrievals when cloud cover exceeds 95%. When overcast retrievals are removed, this difference is reduced to 2 K. Therefore it is recommended that TOVS retrievals be rejected in summer when the retrieved cloud cover is over 95%. Decadal trends also differ greatly between POLES and TOVS primarily owing to the discontinuation of ice station data in the POLES dataset after 1991. Large positive trends in POLES over the central Arctic during spring are absent in TOVS in part because POLES relies on buoy data during the latter third of the data record."
"6603398116;7005453346;7004279859;","A numerical study using the Canadian Regional Climate Model for the PIDCAP period",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036394079&partnerID=40&md5=b78936ab80aabbebd15b1cb0b38a8a17","Simulations of summertime conditions over the BALTEX region using the Canadian Regional Climate Model (CRCM) are compared with observations for the PIDCAP period. A systematic cold bias of the surface temperature was found in a reference simulation made with a version of the CRCM which uses the physical processes package of the third generation global climate model of the Canadian Centre for Climate Modeling and Analysis. This cold bias is found to be due to excessive cloud near the surface. Revision of the cloud scheme, which was originally designed for use in conjunction with relatively coarse resolution of the AGCM, results in a reduction of the cloud cover, improved net radiative flux at the surface and substantial reduction of the cold bias. An associated result is that the lower atmosphere becomes more conditionally unstable which increases the number of convective events. Nevertheless the incidence of convective precipitation events remains unrealistically low."
"7005955015;6506043640;24080547200;6602142887;","A new look at possible connections between solar activity, clouds and climate",2002,"10.1029/2002GL015646","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036955464&doi=10.1029%2f2002GL015646&partnerID=40&md5=1977e96717b989273076e437b73651dc","We present a re-evaluation of the hypothesis of a coupling between galactic cosmic rays, clouds and climate. We have used two independent estimates of low cloud cover from the International Satellite Cloud Climatology Project, covering 16.5 years of data. The cloud cover data are used in conjunction with estimates of galactic cosmic ray flux and measurements of solar irradiance. It is found that solar irradiance correlates better and more consistently with low cloud cover than cosmic ray flux does. The correlations are considerably lower when multichannel retrievals during daytime are used than retrievals using IR-channels only. Due to large autocorrelations, the statistical significance of the results is marginal. A mechanism is suggested whereby solar irradiance variations are amplified by interacting with sea surface temperature (SST), and subsequently low cloud cover. The feasibility of such a mechanism is supported by negative correlations between SSTs and low cloud cover in subtropical regions. © Copyright 2002 by the American Geophysical Union."
"7004942632;6602080205;","Problems in quantifying natural andanthropogenic perturbations to the earth's energy balance",2002,"10.1016/S0074-6142(02)80161-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956737400&doi=10.1016%2fS0074-6142%2802%2980161-9&partnerID=40&md5=5a5d50cbf14443c6495e574139060def","A necessary prerequisite both for understanding past climate change and for predicting future climate change is the ability to quantify the size of the perturbations to the earth's energy balance as a result of either natural or anthropogenic mechanisms which act to drive climate change. Over recent decades, the number of climate change mechanisms being actively considered has grown enormously, but for many of these there are considerable uncertainties in their quantification. This chapter reviews the current status of our knowledge of these mechanisms and illustrates the impact of some of the uncertainties using a simple climate model. Particular attention is given to the impact of aerosols on clouds and the role of volcanic eruptions. © 2002 Elsevier Inc. All rights reserved."
"7410070663;25941200000;","Accounting for unresolved clouds in a 1D infrared radiative transfer model. Part II. Horizontal variability of cloud water path",2002,"10.1175/1520-0469(2002)059<3321:AFUCIA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036937470&doi=10.1175%2f1520-0469%282002%29059%3c3321%3aAFUCIA%3e2.0.CO%3b2&partnerID=40&md5=485dde0c1cbc241eee89994d3d28dd84","A ID infrared radiative transfer that handles clouds with subgrid-scale horizontal variability is developed and tested. It assumes that fluctuations in cloud absorptance optical depth K across layers (and collections of layers) can be described by gamma distributions. Unlike homogeneous clouds, flux incident at a level inside a horizontally inhomogeneous cloud requires explicit computation of transmittance to all other levels in the cloud. Consequently, in addition to estimates of variability for each layer, variability between any two levels must be specified too. Scattering by hydrometeors and a general treatment of cloud overlap are included in this model. Solutions for isothermal and nonisothermal Planck source functions are presented. For the synthetic cloudy atmospheres used here, the new model produces errors for outgoing longwave radiation (OLR) and cloud cooling rates that are typically more than an order of magnitude smaller than those associated with the conventional homogeneous cloud model (as used in all GCMs at present). It is shown that up- and downwelling fluxes and cloud cooling rates can depend much on subgrid-scale variability. For high overcast clouds with realistic variability. OLR can be up to 20 W m-2 more than that predicted by a conventional homogeneous model using the same mean K. At the same time, cooling rate errors at cloud top and cloud base due to the homogeneous assumption can be up to ±25%; the sign depending primarily on mean K and magnitude of variability. For lower, thicker clouds, the homogeneous assumption leads primarily to errors in cloud-top cooling. The new code usually remedies these errors greatly. This model, and its solar counterpart, are used currently in the Canadian Centre for Climate Modelling and Analysis GCM."
"6701689811;","Aerosol radiative forcing over land: Effect of surface and cloud reflection",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036968972&partnerID=40&md5=a6f62cd045997e26e6051d2b80ddd3aa","It is now clearly understood that atmospheric aerosols have a significant impact on climate due to their important role in modifying the incoming solar and outgoing infrared radiation. The question of whether aerosol cools (negative forcing) or warms (positive forcing) the planet depends on the relative dominance of absorbing aerosols. Recent investigations over the tropical Indian Ocean have shown that, irrespective of the comparatively small percentage contribution in optical depth (∼ 11%), soot has an important role in the overall radiative forcing. However, when the amount of absorbing aerosols such as soot are significant, aerosol optical depth and chemical composition are not the only determinants of aerosol climate effects, but the altitude of the aerosol layer and the altitude and type of clouds are also important. In this paper, the aerosol forcing in the presence of clouds and the effect of different surface types (ocean, soil, vegetation, and different combinations of soil and vegetation) are examined based on model simulations, demonstrating that aerosol forcing changes sign from negative (cooling) to positive (warming) when reflection from below (either due to land or clouds) is high."
"7410070663;","Accounting for unresolved clouds in a 1D infrared radiative transfer model. Part I: Solution for radiative transfer, including cloud scattering and overlap",2002,"10.1175/1520-0469(2002)059<3302:AFUCIA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036934251&doi=10.1175%2f1520-0469%282002%29059%3c3302%3aAFUCIA%3e2.0.CO%3b2&partnerID=40&md5=d03fee3d9efafa2c29b3808ab27fcad8","Various aspects of infrared radiative transfer through clouds are investigated. First, three solutions to the IR radiative transfer equation are presented and assessed, each corresponding to a different approximation for the Planck function. It is shown that the differences in results between solutions with linear and exponential dependence of the Planck source function are small for typical vertical resolutions in climate models. Second, a new perturbation-based approach to solving the IR radiative transfer equation with the inclusion of cloud scattering is presented. This scheme follows the standard perturbation method, and allows one to identify the zeroth-order equation with the absorption approximation and the first-order equation as including IR scattering effects. This enables one solution to accurately treat cloudy layers in which cloud scattering is included, and allows for an improved and consistent treatment of absorbing aerosol layers in the absence of cloud by using the zeroth-order equation. This new scheme is more simple and efficient compared to previous perturbation method work for treating infrared absorption and scattering. Last, a general method is devised for calculating the random, maximum, and slantwise overlap of cloud layers, which conveniently integrates into the two-stream radiative transfer solution in this work. For several random and maximum (or slantwise) overlap cloud cases with a wide variation of cloud fractions, the error in the cooling rate is generally less than 1 K day-1 and the error in the radiative flux is generally less than 3 W m-2."
"6701410329;6507040878;","The satellite derived surface radiation budget for BALTEX",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036395683&partnerID=40&md5=cd2a9d1abe54fe83d6e25bf14fca2b61","The Satellite Application Facility for Climate Monitoring (CM-SAF) will derive operationally consistent cloud and radiation parameters in high spatial resolution for an area that covers Europe and part of the north Atlantic Ocean in an off-line mode. The availability of the 12-channel instrument SEVIRI and the GERB onboard the MSG satellite, together with the five-channel AVHRR instrument onboard the NOAA and METOP satellites provides a unique opportunity to derive consistent cloud and radiation parameters. The cloud and surface radiation products will be based on data from the polar orbiting satellites NOAA and METOP for the northern latitudes, and on data from the MSG satellite for the mid-latitudes. To reduce inhomogeneities in the transition from the mid-latitudes to the northern latitudes as much as possible, the same algorithms will be used for both areas. Here a brief description of the planned surface radiation budget products and the selected algorithms is given."
"55476510600;56853406500;","Impact of land use/land cover change on regional hydrometeorology in Amazonia",2002,"10.1029/2000JD000266","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846452446&doi=10.1029%2f2000JD000266&partnerID=40&md5=956dbd6abb2d2228c279ec77ee986f9b","A high-resolution mesoscale model was used to investigate the impact of deforestation in Amazonia. Coherent mesoscale circulations were triggered by the surface heterogeneity; synoptic flow did not eliminate the circulations but advected them away from the location where they were generated. This was substantiated by satellite-derived cloud images. These circulations affected the transport of moisture and heat at the synoptic scale and can affect climate. Adequate parameterizations for these processes should be included in GCMs for more accurate climate simulations. Copyright 2002 by the American Geophysical Union."
"7401796996;7006783796;35494005000;24322892500;6602550636;7101959253;9635764200;","Comparison of stratus cloud properties deduced from surface, GOES, and aircraft data during the March 2000 ARM cloud IOP",2002,"10.1175/1520-0469(2002)059<3265:COSCPD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036937468&doi=10.1175%2f1520-0469%282002%29059%3c3265%3aCOSCPD%3e2.0.CO%3b2&partnerID=40&md5=dd9e7cc96b7ebcd5bfb3ef8bd329771f","Low-level stratus cloud microphysical properties derived from surface and Geostationary Operational Environmental Satellite (GOES) data during the March 2000 cloud intensive observational period (IOP) at the Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site are compared with aircraft in situ measurement. For the surface retrievals, the cloud droplet effective radius and optical depth are retrieved from a δ2-stream radiative transfer model with the input of ground-based measurements, and the cloud liquid water path (LWP) is retrieved from ground-based microwave-radiometer-measured brightness temperature. The satellite results, retrieved from GOES visible, solar-infrared, and infrared radiances, are averaged in a 0.5° × 0.5° box centered on the ARM SGP site. The forward scattering spectrometer probe (FSSP) on the University of North Dakota Citation aircraft provided in situ measurements of the cloud microphysical properties. During the IOP, four low-level stratus cases were intensively observed by the ground- and satellite-based remote sensors and aircraft in situ instruments resulting in a total of 10 h of simultaneous data from the three platforms. In spite of the large differences in temporal and spatial resolution between surface, GOES, and aircraft, the surface retrievals have excellent agreement with the aircraft data overall for the entire 10-h period, and the GOES results agree reasonably well with the surface and aircraft data and have similar trends and magnitudes except for the GOES-derived effective radii, which are typically larger than the surface- and aircraft-derived values. The means and standard deviations of the differences between the surface and aircraft effective radius, LWP, and optical depth are -4% ± 20.1%, -1% ± 31.2%, and 8% ± 29.3%, respectively; while their correlation coefficients are 0.78, 0.92, and 0.89, respectively, during the 10-h period. The differences and correlations between the GOES-8 and aircraft results are of a similar magnitude, except for the droplet sizes. The averaged GOES-derived effective radius is 23% or 1.8 μm greater than the corresponding aircraft values, resulting in a much smaller correlation coefficient of 0.18. Additional surface-satellite datasets were analyzed for time periods when the aircraft was unavailable. When these additional results are combined with the retrievals from the four in situ cases, the means and standard deviations of the differences between the satellite-derived cloud droplet effective radius. LWP, and optical depth and their surface-based counterparts are 16% ± 31.2%, 4% ± 31.6%, and -6% ± 39.9%, respectively. The corresponding correlation coefficients are 0.24, 0.88, and 0.73. The frequency distributions of the two datasets are very similar indicating that the satellite retrieval method should be able to produce reliable statistics of boundary layer cloud properties for use in climate and cloud process models."
"7004613089;7003531755;57199409202;7201425334;","A simple coupled model of tropical Atlantic decadal climate variability",2002,"10.1029/2002GL015874","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036956068&doi=10.1029%2f2002GL015874&partnerID=40&md5=379835908453772796f1de5740b64674","A linear, zonally averaged model of the interaction between the tropical Atlantic (TA) atmosphere and ocean is presented. A balance between evaporation and meridional heat advection in the mixed layer determines the sea surface temperature tendency. The atmosphere is a fixed-depth, sub-cloud layer in which the specific humidity anomaly is determined by a steady-state balance between evaporation, meridional advection, and a parameterized humidity exchange with the free atmosphere. When the model is integrated, forced with observed surface wind anomalies from 1965 to the present, its simulation of the observed sea surface temperature (SST) is realistic and comparable to a simulation with a full ocean GCM. A statistical representation of surface winds and their relationship to the SST gradient across the equator is used to formulate and test a coupled model of their regional variability. Forced on both sides of the equator, in the trade-wind regions, with ""white-noise"" windspeed perturbations, the SST-wind relationship in the near-equatorial region feeds back positively on existing SST anomalies and gives rise to decadal variability. © Copyright 2002 by the American Geophysical Union."
"7103010852;","The impact of satellite observations of the earth's spectrum on climate research",2002,"10.1016/S0074-6142(02)80166-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956728980&doi=10.1016%2fS0074-6142%2802%2980166-8&partnerID=40&md5=1f772a138b6d608698e5f111be390506","This chapter discusses the use of measurements of the spectrum of outgoing longwave radiation, measured from space, as a mechanism for detecting and attributing a cause to climate change. Observations are available from two experiments, one flown by NASA in 1970 (the InfraRed Interferometer Spectrometer, IRIS), and the other flown by Japan's NASDA in 1997 (the Interferometric Monitor for Greenhouse gases, IMG). Both experiments employed a Fourier transform spectrometer, and both were well calibrated using onboard reference targets. The chapter discusses the accuracy and precision of these experiments, and illustrates the difference between average spectra from both. A simulation of the difference spectrum allows an interpretation of the main features of the difference spectrum. It is shown that the observed features are consistent with an increase of CO2, average temperature and CH4 in the period 1970 to 1997. A preliminary analysis of cloudy-sky data indicates that a significant decrease in outgoing radiation between the two periods has been caused by changes in cloud properties. The chapter concludes with the suggestion that in future, small, sensitive spectrally resolving instruments with the measurement capability of IRIS should be flown as passenger instruments on a regular basis. © 2002 Elsevier Inc. All rights reserved."
"7202473760;7004877677;","Validation and results of a scale model of dew deposition in urban environments",2002,"10.1002/joc.856","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036952730&doi=10.1002%2fjoc.856&partnerID=40&md5=470d053e022b0cc0f7082c6b7e392cf3","There is growing interest in urban dew and its significance in questions of urban climate and air pollution deposition, but little research has been undertaken to study it. In this study, a generic, urban residential neighbourhood is modelled out-of-doors at a scale of 0.125, using three wooden houses (1.08 m tall), a concrete pavement (1.0 m in width), a grassed park (7.5 m in half-width) and several small trees (up to 1.5 m tall). The thermal inertia of each house is inflated, according to the internal thermal mass (ITM) approach, so that nocturnal surface temperatures are conserved. First-order validation was achieved through comparison with data collected at nearby full-scale sites in Vancouver, BC, Canada. Moisture accumulation (measured by blotting on grass and by lysimetry) is found to be primarily controlled by nocturnal weather conditions and the intrinsic nature of each substrate, e.g. dewfall is abundant on nights with few clouds and light winds, and on surfaces such as grass and asphalt-shingle roofs, which cool rapidly after sunset. However, these responses are modified by location effects related to the net radiation balance of the surface, which itself is strongly linked to site geometry as expressed by sky view factor and whether surfaces are isolated from heat sources. The dominant mechanism is argued to be the systematic increase in longwave radiation loss that is associated with increased sky view. Results agree with those observed at the full scale and suggest that maps of sky view factor, and knowledge of dew at an open site, can potentially be used to create maps of dew distribution in urban and other complex environments. Copyright © 2002 Royal Meteorological Society."
"7005126685;","Ellesmere Island ice shelves and ice islands",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-32644458828&partnerID=40&md5=32a1da73bca79ba530f3bc384075b2ed","Within fjords along the northwest coast of Ellesmere Island, Nunavut, are several types of ice shelves. Three types have been recognized: sea ice, such as the Ward Hunt Ice Shelf; glacier, such as the Milne Ice Shelf; and composite, such as the Alfred Ernest Ice Shelf. Ice plugs, such as the Nansen Ice Plug, which are composed of multiyear landfast sea ice, and ice shelves are the source of ice islands, such as Hobson's Choice ice island, that drift around the Arctic Ocean. Satellite images are used to characterize the types of ice shelves, ice plugs, and ice islands. Because of winter darkness and persistent summer cloud cover, satellite synthetic aperture radar is the preferred source of image data to identify the changes in, map the areal extent of, and establish a baseline for ice shelves. Ellesmere Island ice shelves have existed since the middle Holocene Epoch and were more extensive in the past. The warming interval during the 20th century has caused a marked reduction in their areal extent. Ice islands are another element of the cryosphere that can be monitored by the use of satellite imagery and can serve as an indicator of climatic amelioration."
"6603839405;6507938064;57196612094;6602165712;7005313745;16508435200;7006499360;7401858327;55902794700;7102445825;6701775894;7403049424;6603916527;7004517840;35567569600;","Accuracy assessment of a large-scale forest cover map of central siberia from synthetic aperture radar",2002,"10.5589/m02-067","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0013006373&doi=10.5589%2fm02-067&partnerID=40&md5=954ed07c8de739b5591a6bd98d2f07a2","Russia's boreal forests host 11% of the world's live forest biomass. They play a critical role in Russia's economy and in stabilizing the global climate. The boreal forests of central and western Siberia represent the largest unbroken tracts of forest in the world. The European Commission funded SIBERIA project aimed at producing a forest map covering an area of 1.2 million square kilometres. Three synthetic aperture radars (SAR) on board the European remote sensing satellites ERS-1 and ERS-2 and the Japanese Earth resources satellite JERS-1 were used to collect remote sensing data. Radar is the only sensor capable of penetrating cloud cover and imaging at night. An adaptive, model-based, contextual classification to derive ranked total growing stock volume classes suitable for large-scale mapping is described. The accuracy assessment of the Siberian forest cover map is presented. The weighted coefficient of agreement κw is calculated to quantify the agreement between the classified map and the reference data. First, the classified map is compared with Russian forest inventory data (κw = 0.72). The inherent uncertainty in the forest inventory data is simulated by allowing for fuzziness. The effect of uncertainty on the unweighted coefficient of agreement κ is stronger than that on the weighted coefficient of agreement κw. Second, the map is compared with a more reliable, independent posterior ground survey by Russian forestry experts (κw = 0.94). The follow-on project SIBERIA-II started in January 2002 and is striving to develop multisensor concepts for greenhouse gas accounting (www.siberia2.uni-jena.de). © 2002 CASI."
"7005135473;57203378050;7005399437;24423610300;","GOES-8 and NOAA-14 AVHRR retrieval of smoke aerosol optical thickness during SCAR-B",2002,"10.1080/01431160110111045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037145648&doi=10.1080%2f01431160110111045&partnerID=40&md5=55624658de4d12a837355ca42840f254","Using the NOAA-14 1-km Advanced Very High Resolution Radiometer (AVHRR) and the Geostationary Operational Environmental Satellite (GOES-8) imager data, smoke aerosol optical thickness (ζ) is retrieved over land during the Smoke, Clouds and Radiation-Brazil (SCAR-B) experiment in Brazil during August-September 1995. The satellite-retrieved ζ values are then compared against ground-based sunphotometer derived ζ values from the Aerosol Robotic Network (AERONET) program. Both the AVHRR and GOES-8 retrieved ζ values are in excellent agreement with the AERONET derived ζ values with linear correlation coefficients of 0.93. A single scattering albedo of 0.90 (at 0.67 μ) provides the best fit between the GOES-8 and AERONET ζ values. The sensitivity of the retrieved ζ to assumed surface albedo and aeorosol single scattering albedo are also examined. A simple multi-spectral thresholding algorithm is used to separate smoke from other features from GOES-8 satellite imagery and regional maps of ζ are provided. Our results show that the aerosol properties used in this paper are adequate to characterize biomass burning aerosols and can be used in studies that model the role of biomass burning on regional climate."
"7003800456;8263760800;7006633800;","Climate forcing of subsonic aviation: Indirect role of sulfate particles via heterogeneous chemistry",2002,"10.1029/2002gl015705","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037113635&doi=10.1029%2f2002gl015705&partnerID=40&md5=778fab5593714a403be0f5d905cf6210","The aerosol budget in the upper troposphere and lower stratosphere may be perturbed by subsonic aviation through direct particle emission or, indirectly, following oxidation of emitted SO2 into sulfuric acid. These additional (or larger) particles produce a radiative forcing (RF) of climate by interacting with solar and planetary radiation, and may also favour formation of high-altitude clouds [Fahey et al., 1999]. The present modeling study focuses on an additional indirect effect of aircraft generated sulfate, namely heterogeneous chemistry on liquid sulfuric acid particles. For the 1992 subsonic aviation case we show that the NOx-driven RF decreases globally from 0.018 Wm-2 to about zero when emission of SO2 and sulfuric acid particles is also included. This decrease is mostly produced by: (1) a smaller ozone increase when the enhancement of sulfuric acid particle surface area density is taken into account (70%), and (2) a direct negative solar RF of aircraft generated sulfate mass (30%). No indirect effects on high-altitude clouds and contrails are considered here."
"55462121400;7005922032;7003886966;7006319021;","Calibration and validation of a regional climate model for pan-Arctic hydrologic simulation",2002,"10.1175/1520-0442(2002)015<3222:CAVOAR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037113305&doi=10.1175%2f1520-0442%282002%29015%3c3222%3aCAVOAR%3e2.0.CO%3b2&partnerID=40&md5=bacc06e9d1670c1dfe4b4b8f61a120b7","A number of polar datasets have recently been released involving in situ measurements, satellite retrievals, and reanalysis output that provide new opportunities to evaluate regional climate in the Arctic. These data have been used to assess a 1-yr pan-Arctic simulation (October 1985-September 1986) performed by a version of the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5) that incorporated the NCAR land surface model (LSM) and a simple thermodynamic sea ice model to investigate interactions between the land surface and atmosphere. The model's standard cloud scheme using relative humidity was replaced by one using simulated cloud liquid water and ice water after a set of short test simulations revealed excessive cloud cover. Model validation concentrates on factors relevant to the water cycle: atmospheric circulation, temperature, surface radiation fluxes, precipitation, and runoff. The model captures general patterns of atmospheric circulation over land. The rms differences from the Historical Arctic Rawinsonde Archive (HARA) rawinsonde winds at 850 hPa are smaller for the simulation (9.8 m s-1) than for the NCEP-NCAR reanalysis (10.5 m s-1) that supplies the model's boundary conditions. For continental watersheds, the model simulates well annual average surface air temperature (bias &lt;2°C) and precipitation (bias &lt;0.5 mm day-1). However, the model has a summer dry bias with monthly precipitation error occasionally exceeding 1 mm day-1. The model simulates the approximate magnitude of spring runoff surge, but annual runoff is less than observed (18%-48% less among the continental watersheds). Analysis of precipitation and surface air temperature errors indicates that further improvements in both evapotranspiration and precipitation are needed to simulate well the full annual water cycle."
"7006575453;7404514776;7202857052;57197655089;23065650200;55476786400;","LIRAD observations of tropical cirrus clouds in MCTEX. Part I: Optical properties and detection of small particles in cold cirrus",2002,"10.1175/1520-0469(2002)059<3145:LOOTCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346319019&doi=10.1175%2f1520-0469%282002%29059%3c3145%3aLOOTCC%3e2.0.CO%3b2&partnerID=40&md5=31b226945d587eec7208032b09e7d320","This paper presents further results on the optical properties of tropical and equatorial cirrus using the light detecting and ranging (lidar) radiometer (LIRAD) method. The results were obtained from observations in the Maritime Continent Thunderstorm Experiment (MCTEX). Values were obtained of cirrus cloud backscatter coefficient, infrared (IR) emittance, optical depth and absorption coefficient, cloud height and depth, and back-scatter-to-extinction ratio. The values agree well with previous results obtained on equatorial cirrus in the Pilot Radiation Observation Experiment (PROBE) and extend those results to lower temperatures. Observations made of lidar linear depolarization ratio show similar trends to those observed in PROBE, extending those results to lower temperatures. Regressions of cloud IR emittance and absorption coefficients are performed as a preliminary tropical dataset for both cloud-resolving and climate models. These regressions are compared with previous regressions on midlatitude and tropical synoptic cirrus clouds. The IR absorption coefficients in tropical and equatorial cirrus appear to be larger than in midlatitude cirrus for temperatures less than -40°C, with the difference increasing toward low temperatures. Thus, a significantly different relationship may be appropriate for tropical cirrus compared to midlatitude cirrus clouds. Effective diameters of small particles in the colder tropical clouds are also measured using the ratio of visible extinction to infrared absorption. A new treatment of multiple scattering is used to correct the ratios. Effective diameters range from 6 to 9.3 μm at the colder temperatures."
"7004364155;56493740900;7004325649;","Defining top-of-the-atmosphere flux reference level for earth radiation budget studies",2002,"10.1175/1520-0442(2002)015<3301:DTOTAF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037113170&doi=10.1175%2f1520-0442%282002%29015%3c3301%3aDTOTAF%3e2.0.CO%3b2&partnerID=40&md5=15e0e1560cb92cc7c43f848fed76271b","To estimate the earth's radiation budget at the top of the atmosphere (TOA) from satellite-measured radiances, it is necessary to account for the finite geometry of the earth and recognize that the earth is a solid body surrounded by a translucent atmosphere of finite thickness that attenuates solar radiation differently at different heights. As a result, in order to account for all of the reflected solar and emitted thermal radiation from the planet by direct integration of satellite-measured radiances, the measurement viewing geometry must be defined at a reference level well above the earth's surface (e.g., 100 km). This ensures that all radiation contributions, including radiation escaping the planet along slant paths above the earth's tangent point, are accounted for. By using a field-of-view (FOV) reference level that is too low (such as the surface reference level), TOA fluxes for most scene types are systematically underestimated by 1-2 W m-2. In addition, since TOA flux represents a flow of radiant energy per unit area, and varies with distance from the earth according to the inverse-square law, a reference level is also needed to define satellite-based TOA fluxes. From theoretical radiative transfer calculations using a model that accounts for spherical geometry, the optimal reference level for defining TOA fluxes in radiation budget studies for the earth is estimated to be approximately 20 km. At this reference level, there is no need to explicitly account for horizontal transmission of solar radiation through the atmosphere in the earth radiation budget calculation. In this context, therefore, the 20-km reference level corresponds to the effective radiative ""top of atmosphere"" for the planet. Although the optimal flux reference level depends slightly on scene type due to differences in effective transmission of solar radiation with cloud height, the difference in flux caused by neglecting the scene-type dependence is less than 0.1%. If an inappropriate TOA flux reference level is used to define satellite TOA fluxes, and horizontal transmission of solar radiation through the planet is not accounted for in the radiation budget equation, systematic errors in net flux of up to 8 W m-2 can result. Since climate models generally use a plane-parallel model approximation to estimate TOA fluxes and the earth radiation budget, they implicitly assume zero horizontal transmission of solar radiation in the radiation budget equation, and do not need to specify a flux reference level. By defining satellite-based TOA flux estimates at a 20-km flux reference level, comparisons with plane-parallel climate model calculations are simplified since there is no need to explicitly correct plane-parallel climate model fluxes for horizontal transmission of solar radiation through a finite earth."
"7102216122;7004868225;6701715928;","A GIS based empirical model to simulate air temperature variations in the Göteborg urban area during the night",2002,"10.3354/cr022215","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037021205&doi=10.3354%2fcr022215&partnerID=40&md5=14a8b221476c65996ba6f231fe567efc","This paper presents a GIS based empirical model to simulate wind and/or air temperature variations over land. The technique is based on meteorological data (wind direction and wind speed, temperature and cloud cover) from one permanent reference station, a digital local climate map and a digital land use map. The focus of the paper is to apply and evaluate the technique for clear and calm night-time weather conditions in Göteborg, Sweden. Hourly data from a monitoring network including 31 temperature stations are used in the verification of simulations made using the model. These data are also used for a description of geographical factors that influence air temperature variations in the Göteborg urban district. The technique is a potential tool for urban planning purposes but the verification shows that further improvements are needed. The main problems identified are related to details in the climate map but also to some of the algorithms that need to be refined."
"55951088700;","Distributional change and conservation on the Andean flank: A palaeoecological perspective",2002,"10.1046/j.1466-822X.2002.00305.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036881645&doi=10.1046%2fj.1466-822X.2002.00305.x&partnerID=40&md5=db8a5d2e41bb50e1c23b872fe44ddc99","Aim To review the insights that palaeoecology can offer on the threat posed to Andean communities by global climate change. Location The geographical focus is the eastern flank of the tropical Andes, with particular reference to Peru. Method The article presents a synthetic review of the problem. Results Species-rich communities of the eastern Andean flank are threatened both by development and climate change. If, as predicted, the cloudbase and frost line lifts 600 m elevation this century, there will be a substantial loss of cloud forest habitat. Palaeoecology provides insights on the location and nature of past ecotones, the continuity of niche availability, and estimates for rates and modes of migration. With further warming and drying of lower montane regions, upslope migration of species will be individualistic: a new equilibrium with the altered climate is unlikely to be attained. The zone of agriculture will move upslope faster than the migrating trees and so landscape conversion will negate the ability of some species to respond to the new conditions. Conservation of the lower reaches of modern cloud forest is advocated as a means to limit this foreseeable extinction event. Main Conclusions Climate change will induce changes in plant and animal communities. Human disturbance will invade climatically marginal agricultural lands at the pace of climate change. Rapid migratory response such as that witnessed at the onset of the Holocene may not be evident as climates warm, because Holocene climatic stability has reduced outlying upslope populations that may have served as expansion nuclei. Conservation must aim to maintain plant and animal niches, rather than particular communities of species."
"55897045400;7005981420;7006518279;57203233100;","Atmospheric multiple scattering effects on GLAS altimetry - Part II: Analysis of expected errors in antarctic altitude measurements",2002,"10.1109/TGRS.2002.803849","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036875868&doi=10.1109%2fTGRS.2002.803849&partnerID=40&md5=923fa1c43dd713203d7995598f956b60","The altimetry bias in the Geoscience Laser Altimeter System or other laser altimeters resulting from atmospheric multiple scattering is studied in relationship to current knowledge of cloud properties over the Antarctic Plateau. Estimates of seasonal and interannual changes in the bias are presented. Results show the bias in altitude from multiple scattering in clouds would be a significant error source without correction. The selective use of low-optical-depth clouds or cloud-free observations, as well as improved analysis of the return pulse such as by the Gaussian method used here, is necessary to minimize the surface altitude errors. The magnitude of the bias is affected by variations in cloud height, cloud effective particle size, and optical depth. Inter annual variations in these properties as well as in cloud cover fraction could lead to significant year-to-year variations in the altitude bias. Although cloud-free observations reduce biases in surface elevation measurements from space, over Antarctica these may often include near-surface blowing snow, also a source of scattering-induced delay. With careful selection and analysis of data, laser altimetry specifications can be met."
"7005212820;7202208382;","Interactions between cloud microphysics and cumulus convection in a general circulation model",2002,"10.1175/1520-0469(2002)059<3074:IBCMAC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036871411&doi=10.1175%2f1520-0469%282002%29059%3c3074%3aIBCMAC%3e2.0.CO%3b2&partnerID=40&md5=75a8d2f3023ca1db0864a8c0a54a25ff","In the Colorado State University general circulation model, cumulus detrainment of cloud water and cloud ice has been, up to now, the only direct coupling between convective and large-scale condensation processes. This one-way interaction from the convective to the large-scale environment parameterizes, in a highly simplified manner, the growth of anvils spreading horizontally at the tops of narrow cumulus updrafts. The reverse interaction from the large-scale to the convective updrafts, through which large-scale cloud water and cloud ice can affect microphysical processes occurring in individual convective updrafts, is missing. In addition, the effects of compensating subsidence on cloud water and cloud ice are not taken into account. A new parameterization of convection, called ""EAUCUP,"" has been developed, in which large-scale water vapor, cloud water, and cloud ice are allowed to enter the sides of the convective updrafts and can be lifted to the tops of the clouds. As the various water species are lifted, cloud microphysical processes take place, removing excess cloud water and cloud ice in the form of rain and snow. The partitioning of condensed vapor between cloud water and cloud ice, and between rain and snow, is based on temperature. The effects of compensating subsidence on the large-scale water vapor, cloud water, and cloud ice are computed separately. Convective rain is assumed to fall instantaneously to the surface. Three treatments of the convective snow are tested: 1) assuming that all snow is detrained at the tops of convective updrafts, 2) assuming that all snow falls outside of the updrafts and may evaporate, and 3) assuming that snow falls entirely inside the updrafts and melts to form rain. Including entrainment of large-scale cloud water and cloud ice inside the updrafts, large-scale compensating subsidence unifies the parameterizations of large-scale cloud microphysics and convection, but have a lesser impact than the treatment of convective snow on the simulated climate. Differences between the three alternate treatments of convective snow are discussed. Emphasis is on the change in the convective, large-scale, and radiative tendencies of temperature, and change in the convective and large-scale tendencies of water vapor, cloud water, cloud ice, and snow. Below the stratiform anvils, the change in latent heating due to the change in both convective and large-scale heatings contributes a major part to the differences in diabatic heating among the three simulations. Above the stratiform anvils, differences in the diabatic heating between the three simulations result primarily because of differences in the longwave radiative cooling. In particular, detraining convective snow at the tops of convective updrafts yields a strong increase in the longwave radiative cooling associated with increased upper-tropospheric cloudiness. The simulated climate is wetter and colder when convective snow is detrained at the tops of the updrafts than when it is detrained on the sides of the updrafts or when it falls entirely inside the updrafts. This result highlights the importance of the treatment of the ice phase and associated precipitation in the convective cloud models used in cumulus parameterizations."
"7003666669;7103023423;26643227600;23479202500;","The thermodynamic influence of subgrid orography in a global climate model",2002,"10.1007/s00382-002-0257-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036868066&doi=10.1007%2fs00382-002-0257-5&partnerID=40&md5=6bb42e28c96f4a3d504d9127b5a6aa3e","Assessments of the impacts of climate change typically require information at scales of 10 km or less. Such a resolution in global climate simulations is unlikely for at least two decades. We have developed an alternative to explicit resolution that provides a framework for meeting the needs of climate change impact assessment much sooner. We have applied to a global climate model a physically based subgrid-scale treatment of the influence of orography on temperature, clouds, precipitation, and land surface hydrology. The treatment represents subgrid variations in surface elevation in terms of fractional area distributions of discrete elevation classes. For each class it calculates the height rise/descent of air parcels traveling through the grid cell, and applies the influence of the rise/descent to the temperature and humidity profiles of the elevation class. Cloud, radiative, and surface processes are calculated separately for each elevation class using the same physical parametrizations used by the model without the subgrid orography parametrization. The simulated climate fields for each elevation class can then be distributed in post- processing according to the spatial distribution of surface elevation within each grid cell. Parallel 10-year simulations with and without the subgrid treatment have been performed. The simulated temperature, precipitation and snow water are mapped to 2.5-minute (∼5 km) resolution and compared with gridded analyses of station measurements. The simulation with the subgrid scheme produces a much more realistic distribution of snow water and significantly more realistic distributions of temperature and precipitation than the simulation without the subgrid scheme. Moreover, the 250-km grid cell means of most other fields are virtually unchanged by the subgrid scheme. This suggests that the tuning of the climate model without the subgrid scheme is also applicable to the model with the scheme."
"24722339600;7103016965;25953950400;","Autoconversion rate bias in stratiform boundary layer cloud parameterizations",2002,"10.1016/S0169-8095(02)00071-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036844999&doi=10.1016%2fS0169-8095%2802%2900071-6&partnerID=40&md5=4fd59b90eed45dda4073f83845973cf9","Because of their large grid-box size, global climate models do not explicitly represent small-scale processes occurring in cloud systems in the marine boundary layer. One such process, which is thought to have an important climatological effect, is the production of warm rain. Parameterizations of this process typically partition the liquid water into a cloud and a rain component. The rate of conversion (autoconversion) of cloud to rainwater is expressed as a convex function of the local cloud liquid water content. It is well known that the distribution of cloud liquid water content within boundary layer cloud systems is spatially nonuniform. This would result in biased mean autoconversion rates if no attempt is made to model subgrid variability. Three formulations are examined, with increasing complexity, that can be used to model the distribution of liquid water content within a model grid box and assess how well each predicts the mean autoconversion rate. Assuming complete homogeneity of cloud liquid water within a model grid box results in large biases. The use of cloud fraction to partition the grid box into cloudy and clear regions substantially reduces the biases. The most significant reduction of the biases is achieved with a Gaussian distribution of saturation excess within the grid box. With this formulation, which could be facilitated using look-up tables, biases can be removed in a way consistent with the underlying distribution of saturation excess. A simple parameterization is presented that corrects much of the bias using simple algebraic expressions. It is demonstrated that to accurately calculate the mean autoconversion rate, an accurate parameterization of the width of the saturation excess distribution is required. © 2002 Published by Elsevier Science B.V."
"55547129338;7401548835;","Projected impact of climate change on the energy budget of the Arctic ocean by a global climate model",2002,"10.1175/1520-0442(2002)015<3028:PIOCCO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036863528&doi=10.1175%2f1520-0442%282002%29015%3c3028%3aPIOCCO%3e2.0.CO%3b2&partnerID=40&md5=70b7cda87198f98f99afa47dc8cfc56f","The annual energy budget of the Arctic Ocean is characterized by a net heat loss at the air-sea interface that is balanced by oceanic heat transport into the Arctic. Two 150-yr simulations (1950-2099) of a global climate model are used to examine how this balance might change if atmospheric greenhouse gases (GHGs) increase. One is a control simulation for the present climate with constant 1950 atmospheric composition, and the other is a transient experiment with observed GHGs from 1950 to 1990 and 0.5% annual compounded increases of CO2 after 1990. For the present climate the model agrees well with observations of radiative fluxes at the top of the atmosphere, atmospheric advective energy transport into the Arctic, and surface air temperature. It also simulates the seasonal cycle and summer increase of cloud cover and the seasonal cycle of sea ice cover. In addition, the changes in high-latitude surface air temperature and sea ice cover in the GHG experiment are consistent with observed changes during the last 40 years. Relative to the control, the last 50-yr period of the GHG experiment indicates that even though the net annual incident solar radiation at the surface decreases by 4.6 W m-2 (because of greater cloud cover and increased cloud optical depth), the absorbed solar radiation increases by 2.8 W m-2 (because of less sea ice). Increased cloud cover and warmer air also cause increased downward thermal radiation at the surface so that the net radiation into the ocean increases by 5.0 W m-2. The annual increase in radiation into the ocean, however, is compensated by larger increases in sensible and latent heat fluxes out of the ocean. Although the net energy loss from the ocean surface increases by 0.8 W m-2, this is less than the interannual variability, and the increase may not indicate a long-term trend. The seasonal cycle of heat fluxes is significantly enhanced. The downward surface heat flux increases in summer (maximum of 19 W m-2, or 23% in June) while the upward heat flux increases in winter (maximum of 16 W m-2, or 28% in November). The increased downward flux in summer is due to a combination of increases in absorbed solar and thermal radiation and smaller losses of sensible and latent heat. The increased heat loss in winter is due to increased sensible and latent heat fluxes, which in turn are due to reduced sea ice cover. On the other hand, the seasonal cycle of surface air temperature is damped, as there is a large increase in winter temperature but little change in summer. The changes that occur in the various quantities exhibit spatial variability, with the changes being generally larger in coastal areas and at the ice margins."
"35546736600;7004305415;7004563885;7801566289;6508150220;","MODIS snow-cover products",2002,"10.1016/S0034-4257(02)00095-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036847118&doi=10.1016%2fS0034-4257%2802%2900095-0&partnerID=40&md5=51834c27e5d1bc49d15244551e6d8725","On December 18, 1999, the Terra satellite was launched with a complement of five instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS). Many geophysical products are derived from MODIS data including global snow-cover products. MODIS snow and ice products have been available through the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) since September 13, 2000. MODIS snow-cover products represent potential improvement to or enhancement of the currently available operational products mainly because the MODIS products are global and 500-m resolution, and have the capability to separate most snow and clouds. The MODIS snow-mapping algorithms are automated, which means that a consistent data set may be generated for long-term climate studies that require snow-cover information. Extensive quality assurance (QA) information is stored with the products. The MODIS snow product suite begins with a 500-m resolution, 2330-km swath snow-cover map, which is then gridded to an integerized sinusoidal grid to produce daily and 8-day composite tile products. The sequence proceeds to a climate-modeling grid (CMG) product at 0.05° resolution, with both daily and 8-day composite products. Each pixel of the daily CMG contains fraction of snow cover from 40% to 100%. Measured errors of commission in the CMG are low, for example, on the continent of Australia in the spring, they vary from 0.02% to 0.10%. Near-term enhancements include daily snow albedo and fractional snow cover. A case study from March 6, 2000, involving MODIS data and field and aircraft measurements, is presented to show some early validation work. © 2002 Elsevier Science Inc. All rights reserved."
"6701534440;35609878300;55406092600;7004027377;6603387762;7006117817;7003461830;7005246513;6603964947;6507475320;22958783000;57202402302;7004125919;6604005753;","Global climatological features in a simulation using the CPTEC-COLA AGCM",2002,"10.1175/1520-0442(2002)015<2965:GCFIAS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036863028&doi=10.1175%2f1520-0442%282002%29015%3c2965%3aGCFIAS%3e2.0.CO%3b2&partnerID=40&md5=849c3db1e61b800925b367493a3c4505","The Center for Weather Forecasting and Climate Studies-Center for Ocean-Land-Atmosphere Studies (CPTEC-COLA) atmospheric general circulation model (AGCM) is integrated with nine initial conditions for 10 yr to obtain the model climate in an ensemble mode. The global climatological characteristics simulated by the model are compared with observational data, and emphasis is given to the Southern Hemisphere and South America. Evaluation of the model's performance is presented by showing systematic errors of several variables, and anomaly correlation and reproducibility are applied to precipitation. The model is able to simulate the main features of the global climate, and the results are consistent with analyses of other AGCMs. The seasonal cycle is reproduced well in all analyzed variables, and systematic errors occur at the same regions in different seasons. The Southern Hemisphere convergence zones are simulated reasonably well, although the model overestimates precipitation in the southern portions and underestimates it in the northern portions of these systems. The high- and low-level main circulation features such as the subtropical highs, subtropical jet streams, and storm tracks are depicted well by the model, albeit with different intensities from the reanalysis. The stationary waves of the Northern and Southern Hemispheres are weaker in the model; however, the dominant wavenumbers are similar to the observations. The energy budget analysis shows values of some radiative fluxes that are close to observations, but the unbalanced fluxes in the atmosphere and at the surface indicate that the radiation and cloud scheme parameterizations need to be improved. Besides these improvements, changes in the convection scheme and higher horizontal resolution to represent orographic effects better are being planned to improve the model's performance."
"7202145115;36862677400;","An important constraint on tropical cloud - Climate feedback",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081148572&partnerID=40&md5=3ce96f1133749967ad9fbdf2ae4d3ebf","Tropical convective anvil clouds detrain preferentially near 200 hPa. It is argued here that this occurs because clear-sky radiative cooling decreases rapidly near 200 hPa. This rapid decline of clear-sky longwave cooling occurs because radiative emission from water vapor becomes inefficient above 200 hPa. The emission from water vapor becomes less important that the emission from CO2 because the saturation vapor pressure is so very low at the temperatures above 200 hPa. This suggests that the temperature at the detrainment level, and consequently the emission temperature of tropical anvil clouds, will remain constant during climate change. This constraint has very important implications for the potential role of tropical convective clouds in climate feedback, since it means that the emission temperatures of tropical anvil clouds and upper tropospheric water vapor are essentially independent of the surface temperature, so long as the tropopause is colder than the temperature where emission from water vapor becomes relatively small."
"56000281400;7007108728;","Effects of air mass origin on Arctic cloud microphysical parameters for April 1998 during FIRE.ACE",2002,"10.1029/2000jc000440","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037110334&doi=10.1029%2f2000jc000440&partnerID=40&md5=5a660d526d05f14d6dd1b721ab6dda04","Observations collected in April 1998 using the Canadian Convair-580 during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment-Arctic Cloud Experiment (FIRE.ACE) are used to study cloud microphysics over the Arctic Ocean. Cloud microphysical parameters in climate models are specified as either constants or specific relationships based on cloud systems originating from either the ocean or land. The Arctic Ocean during winter and spring is mainly covered with ice. Because of this condition, the influence of the Arctic Ocean on cloud systems can be very different as compared to that of the midlatitude ocean. Air mass back-trajectories calculated from the Canadian Meteorological Center (CMC) model outputs were used to define the origin of air masses as either the Pacific Ocean (PO) or the Arctic Ocean (AO). The uncertainty in specifying the origin of the air mass was less than 20%. The PO mean aerosol number concentration (Na) from the aircraft measurements was larger (108 cm-3) than for the AO cases (41 cm-3). The PO mean droplet number concentration (Nd) was 48 cm-3 in comparison to 77 cm-3 for the AO cases. The droplet effective radii (reff) for the AO and PO cases were 9.3 and 5.6 μm, respectively. Liquid water content (ice water content) changed from 0.05 (0.01) g m-3 for the AO cases to 0.13 (0.03) g m-3 for the PO cases. The averaged ice crystal number concentration was 20 L-1 for the PO cases and 10 L-1 for the AO cases. For April 1998, a statistical significance test on mean values at the 85% confidence level showed that the AO and PO cases had distinct microphysical and aerosol characteristics."
"6507206337;7006274990;","A method for separating Antarctic postglacial rebound and ice mass balance using future ICESat Geoscience Laser Altimeter System, Gravity Recovery and Climate Experiment, and GPS satellite data",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037058211&partnerID=40&md5=81da58c371f25d2932700d8dc27e7749","Measurements of ice elevation from the Geoscience Laser Altimeter System (GLAS) aboard the Ice, Cloud, and Land Elevation Satellite can be combined with time-variable geoid measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to learn about ongoing changes in polar ice mass and viscoelastic rebound of the lithosphere under the ice sheet. We estimate the accuracy in recovering the spatially varying ice mass trend and postglacial rebound signals for Antarctica, from combining 5 years of simulated GRACE and GLAS data. We obtain root-mean square accuracies of 5.3 and 19.9 mm yr-1 for postglacial rebound and ice mass trend, respectively, when smoothed over 250 km scales. The largest source of error in the combined signals is the effect of the unknown time-variable accumulation on the density of the ice column. To estimate this contribution and so obtain better estimates of ice mass trend and postglacial rebound, we add Global Positioning System (GPS) measurements of vertical velocities as additional constraints. Using an empirical relation between the errors in postglacial rebound and ice mass trend that result from the unknown density variation within the ice column, we are able to solve for all three unknowns in the problem: ice mass trend, postglacial rebound, and the snow compaction trend. The addition of a plausible distribution of GPS measurements reduces the errors in estimates of postglacial rebound and ice mass trend to 3.4 and 15.9 mm yr-1, respectively."
"7006716689;24556796800;","The surface ocean - Lower atmosphere study (SOLAS)",2002,"10.1016/S1352-2310(02)00327-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036787643&doi=10.1016%2fS1352-2310%2802%2900327-8&partnerID=40&md5=92d38cc7c84147747ea1e5375e577861",[No abstract available]
"6603175750;7004909806;24322005900;","Preliminary studies on the variational assimilation of cloud-radiation observations",2002,"10.1256/qj.01.192","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036821056&doi=10.1256%2fqj.01.192&partnerID=40&md5=ee0b1a5f25a71c3bbbd9062e6e14b8b4","A linearized cloud scheme and a radiation scheme including cloud effects have been developed at the ECMWF to assimilate cloud properties in the framework of the 4D-Var system. To investigate the potential of those schemes to modify the model temperature, humidity and cloud profiles to produce a better match to the observed radiation fluxes. 1D-Var experiments have been carried out first with simulated observations and then using data from the Atmospheric Radiation Measurement programme. The assimilation experiments with simulated observations show that it is possible to reduce or increase the cloud cover when using the ID-Var approach to improve the fit of the model to the observed radiative fluxes. However, there is also a potential danger of adjusting the model state to the observed fluxes with resulting temperature and humidity profiles very different from the true ones. The assimilation of real observations demonstrates the capability of 1D-Var to improve the analysis of temperature and specific humidity. Some weaknesses have also been identified, such as the problem of triggering clouds and the need, in some situations, for other observations to complement the surface ones."
"36907291300;7004540083;55471597600;7004384155;","Did the eruption of the Mt. Pinatubo volcano affect cirrus properties?",2002,"10.1175/1520-0442(2002)015<2806:DTEOTM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036809819&doi=10.1175%2f1520-0442%282002%29015%3c2806%3aDTEOTM%3e2.0.CO%3b2&partnerID=40&md5=30bb144f67b916db7f9f543203eb6dd7","Some observations suggest that the volcanic aerosols produced by the Mt. Pinatubo eruption may have altered cirrus. The authors look for evidence that such modification of cirrus is extensive enough to be climatically significant by comparing three satellite-based cirrus datasets produced by the International Satellite Cloud Climatology Project (ISCCP) analysis, the split-window analysis, and the Improved Initialization Inversion (31) analysis. Since the former two have not been compared in detail before, such a comparison was conducted here. When applied to the Advanced Very High Resolution Radiometer (AVHRR) data, both the ISCCP and split-window analyses identify about 0.2-0.3 cirrus cloud amounts in tropical latitudes: however, there are detailed differences of classification for about half of these clouds. The discrepancies are attributed to the simplified assumptions made by both methods. The latter two datasets are derived from infrared radiances, so they are less sensitive to volcanic aerosols than the ISCCP analysis. After the Mt. Pinatubo eruption, the ISCCP results indicate a notable decrease of thin cirrus over ocean, accompanied by a comparable increase of altocumulus and cumulus clouds; over land, there are no significant changes. In contrast, results from the split-window and 31 analyses show little change in thin cirrus amount over either ocean or land that is associated with the volcanic eruption. The ISCCP results can, therefore, be understood as a misclassification of thin cirrus because additional reflected sunlight by the volcanic aerosol makes the cirrus clouds appear to be optically thicker. Examinations of the split-window signature show no significant change in infrared emissivity (or optical thickness). These results indicate that the Mt. Pinatubo volcanic aerosol did not have a significant systematic effect on tropical cirrus properties (such as cloud amount and optical thickness), but do not exclude the occurrence of temporary, local effects. Hence, these results suggest that there is no significant climate feedback produced by aerosol-cirrus-radiative interactions."
"7202764182;7005524665;7102910034;7103199552;","Late glacial-Holocene atmospheric circulation and precipitation in the northeast United States inferred from modern calibrated stable oxygen and carbon isotopes",2002,"10.1130/0016-7606(2002)114<1326:LGHACA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036810969&doi=10.1130%2f0016-7606%282002%29114%3c1326%3aLGHACA%3e2.0.CO%3b2&partnerID=40&md5=1ad61ba0a5af0a6c88a279c6350395a7","As global climate changes because of anthropogenic influences, it has become critical to better understand past climate and its various forcing mechanisms as a baseline for future comparison. To this end, we present a continental isotopic record from an 11.2-m-long wetland piston core sampled at 10-50 yr resolution; the core was taken in the heavily populated, economically vibrant northeastern United States (adjacent to Fayetteville Green Lake) and spans 14,600-3200 cal. yr B.P. We use a historically based correlation between δ18Ocalcite obtained from individual varves in a box core from Fayetteville Green Lake and winter atmospheric circulation over the northeast United States to examine the way in which changes in winter circulation have influenced δ18O in precipitation from 14,600 to 3200 cal. yr B.P. Our correlation analysis suggests that in periods during which the circumpolar westerlies are expanded, storms track more frequently from the Gulf of Mexico region, delivering precipitation with relatively high δ18O values to the study site. By contrast, contracted westerlies result in more frequent low-δ18Oprecipitation cross-continental storms. By using this relationship we model winter-vortex latitudes over the northeast United States for the prehistoric oxygen isotope record, focusing on millennial-scale change, abrupt transitions, and multidecadal- to centennial-scale variability. The δ18Ocalcite and winter-vortex latitude records are characterized by a long-term asymmetric change interrupted by two notable, abrupt transitions at ca. 11,600 cal. yr B.P. and ca. 5200 cal. yr B.P. Several forcing mechanisms are considered including precession of the equinoxes (millennial-scale), ice-sheet-margin retreat (millennial-scale), thermohaline circulation (abrupt transitions), and ocean-atmosphere linkages (decadal to centennial scale). Analysis of historical δ13Ccalcite values from a box core of varved Fayetteville Green Lake sediment and correlation of these values to early summer precipitation amounts reveal a relationship in which high δ13Ccalcite values (usually attributed to greater primary productivity) correspond with low annual precipitation amounts. From this relationship, we propose a climate-control hypothesis in which less early summer precipitation enhances productivity by increasing sunlight availability through reduced total cloud cover. We use this relationship to interpret early summer precipitation and cloud cover for the period from 14,600 to 3200 cal. yr B.P. The δ13Ccalcite, precipitation and cloud-cover data are characterized by fluctuations about a mean value with multiple abrupt transitions occurring throughout the length of the record; there is no obvious trend in the δ13Ccalcite data. Spectral analysis indicates that both the δ13Ccalcite and δ18Ocalcite data are characterized by a variety of time scales with the most significant periods in the multidecadal to centennial time frame, corroborating other research that has determined a strong multidecadal to centennial periodicity in late glacial-Holocene climate proxy records."
"57211224269;","Effects of large-scale mountains on surface climate - A coupled ocean-atmosphere general circulation model study",2002,"10.2151/jmsj.80.1165","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036822416&doi=10.2151%2fjmsj.80.1165&partnerID=40&md5=5024724e912c33ea3f886d25fd733e21","Effect of mountain uplift on climate is investigated by a global coupled ocean-atmosphere general circulation model with an emphasis on surface temperature changes. Results of the no-mountain run (NM) are compared with those of the control run with the present-day orography (M). When the lapserate effect is eliminated, continent interior becomes warmer with mountain uplift because clouds become fewer and the surface drier due to decreased moisture transport. On the other hand, South Asia and East Asia become cooler because summer monsoon precipitation is stronger, which makes the land surface wetter and increases clouds. Over the ocean, the existence of orography has a role to reduce sea surface temperatures (SST), particularly over the subtropical eastern oceans. This occurs because evaporation is larger due to stronger trade winds and also less solar radiation reaches the surface due to more low-level clouds, both associated with stronger subtropical anticyclones in M. The subtropical gyre is stronger in M than in NM, and therefore, the Kuroshio Current is stronger in M. When the effect of the ocean general circulation is not included, the SST over the western north Pacific becomes much lower in M than in NM because of stronger cold air outbreak from Siberia in winter in M. Thus, the ocean circulation changes act to reduce the SST changes by heat transport."
"7102870914;57202301596;","Inter-hemispheric decadal variations in SST, surface wind, heat flux and cloud cover over the Atlantic Ocean",2002,"10.2151/jmsj.80.1199","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036822426&doi=10.2151%2fjmsj.80.1199&partnerID=40&md5=ab4b22fce1fa747ace4a2757a81bb292","Atlantic decadal climate variations are studied using marine meteorological observations. To remove artificial interhemispheric correlation, we perform empirical orthogonal function (EOF) analysis of sea surface temperature (SST) variability separately for the North and South Atlantic. The first EOF for the North (South) Atlantic in the decadal (8-16 years) band features a meridional tripole (dipole). In the tropics, the northern and southern leading EOFs form a meridional dipole with a center of action at 15° on either side of the equator. The leading sea level pressure (SLP) EOFs for the North and South Atlantic each feature a center of action that is displaced poleward of the tropical SST extreme, at 30° latitude. The SLP center of action in the North Atlantic has a barotropic structure and contributes significantly to surface wind variability in the tropics. Despite being derived from statistically independent data samples, the principle components for the leading SST and SLP EOFs (four in total) are significantly correlated with one another, indicative of the existence of an interhemispheric mode spanning the entire Atlantic Ocean. The same analysis for a longer SST record suggests that this pan-Atlantic decadal variability exists throughout the 20th century. In the North Atlantic, composite analysis of wind velocity and heat fluxes based on the PCs of the leading SST modes indicates that wind-induced latent heat flux is the major forcing for decadal SST variability. In the South Atlantic, by contrast, wind anomalies are neither organized in space nor in geostrophic balance with SLP, a problem likely due to poor sampling there as indicated by a comparison with well-sampled satellite measurements. Spatially coherent anomalies of low-level cloud cover are found to be associated with the tropical Atlantic dipole, with increased (decreased) cloudiness over the cold (warm) lobe. These low-level cloud anomalies do not appear to be associated with significant surface wind convergence, unlike the deep convective clouds near the equator. By shielding solar radiation, these low-level cloud anomalies act to reinforce the underlying SST anomalies, reducing the Newtonian cooling rate for SST by as much as 30%."
"55665325500;7006936301;6701402091;35780547900;7006295022;7102799735;7003970894;49160979500;7102173600;35866679700;7004586388;18437501600;16687083000;7005941690;7005981420;35517306100;","ICESat's laser measurements of polar ice, atmosphere, ocean, and land",2002,"10.1016/S0264-3707(02)00042-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036785227&doi=10.1016%2fS0264-3707%2802%2900042-X&partnerID=40&md5=64999ee4e8884ad1a3f7c5858dd836e2","The Ice, Cloud and Land Elevation Satellite (ICESat) mission will measure changes in elevation of the Greenland and Antarctic ice sheets as part of NASA's Earth Observing System (EOS) of satellites. Time-series of elevation changes will enable determination of the present-day mass balance of the ice sheets, study of associations between observed ice changes and polar climate, and estimation of the present and future contributions of the ice sheets to global sea level rise. Other scientific objectives of ICESat include: global measurements of cloud heights and the vertical structure of clouds and aerosols; precise measurements of land topography and vegetation canopy heights; and measurements of sea ice roughness, sea ice thickness, ocean surface elevations, and surface reflectivity. The Geoscience Laser Altimeter System (GLAS) on ICESat has a 1064 nm laser channel for surface altimetry and dense cloud heights and a 532 nm lidar channel for the vertical distribution of clouds and aerosols. The predicted accuracy for the surface-elevation measurements is 15 cm, averaged over 60 m diameter laser footprints spaced at 172 m along-track. The orbital altitude will be around 600 km at an inclination of 94° with a 183-day repeat pattern. The on-board GPS receiver will enable radial orbit determinations to better than 5 cm, and star-trackers will enable footprints to be located to 6 m horizontally. The spacecraft attitude will be controlled to point the laser beam to within ± 35 m of reference surface tracks at high latitudes. ICESat is designed to operate for 3-5 years and should be followed by successive missions to measure ice changes for at least 15 years. © 2002 Published by Elsevier Science Ltd."
"7005956443;","Smoothing forecast ensembles with fitted probability distributions",2002,"10.1256/qj.01.215","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036821009&doi=10.1256%2fqj.01.215&partnerID=40&md5=1443ac33b0f99463a3dd1d388db51af9","Forecast ensembles from the European Centre for Medium-Range Weather Forecasts Ensemble Prediction System for surface-weather variables are smoothed by fitting Gaussian distributions. The possibility of bifurcation or other non-Gaussian behaviours in an ensemble is allowed for by including probability mixtures of two Gaussian distributions when justified by the data. Variables that are clearly non-Gaussian (wind speed and cloud cover) are transformed before fitting, and multivariate data with dimensions as high as four are considered. The smoothed ensembles provide more-accurate quantile and probability estimates in a perfect-model setting, particularly for small ensemble sizes and more-extreme events. This advantage increases in the presence of random errors in the ensemble means, but diminishes for underdispersed ensembles. Allowing representation of ensembles as Gaussian mixtures also leads to a sharper 'spread-skill' relationship in the data considered."
"7201504886;","Entrainment in stratocumulus-topped mixed layers",2002,"10.1256/qj.01.202","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036820811&doi=10.1256%2fqj.01.202&partnerID=40&md5=82a68f3c1a10667b984cc5d2e48e6643","Mixed-layer theory is used to synthesize and evaluate recently proposed entrainment parametrizations (rules) for the stratocumulus-topped boundary layer. The results illustrate that recently proposed entrainment rules exhibit marked differences. Significant differences are found between rules derived from a single set of simulations and rules derived from different sets of simulations. Such differences imply steady-state boundary layers that can differ by as much as a factor of two in climatologically important properties such as vertically integrated liquid water and boundary-layer depth. In addition, surface fluxes depend significantly on entrainment, as do different measures for the limits of applicability of the mixed-layer theory. Moreover, differences among proposed entrainment rules yield steady states with different equilibrium sensitivities; models closed with some rules are more sensitive to divergence while others are more sensitive to variations in the sea surface temperature. Overall we expect that these differences should be evident in the climatology and climate sensitivity of stratocumulus derived from models which use these rules. This degree of sensitivity encourages attempts to bound entrainment rules observationally, by requiring consistency with the observed stratocumulus climatology. The analysis also encourages the use of somewhat simpler strategies for the parametrization of the stratocumulus-topped boundary layer in large-scale models."
"7005135473;57203378050;","Shortwave Aerosol Radiative Forcing from MODIS and CERES observations over the oceans",2002,"10.1029/2002GL014803","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037107319&doi=10.1029%2f2002GL014803&partnerID=40&md5=788383bc0d91a110b28e8a8a13915d55","Using spatially and temporally collocated data sets from the Clouds and Earth's Radiant Energy System (CERES) and Moderate-Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra satellite, a new strategy is presented for studying the Shortwave Aerosol Radiative Forcing (SWARF) over the global oceans. Using collocated data, for September 2000, the global averaged optical thickness (τ0.55) for cloud-free CERES pixels is 0.07 with a SWARF of -6 Wm-2. The τ0.55 and SWARF values derived from two independent instruments are in excellent agreement with the following relationship: SWARF = 0.35 -105.34τ0.55 +61.47τ0.552 (0 ≤ τ0.55 ≤ 0.7) Wm-2. The synergistic use of the MODIS and CERES data sets can be used to provide independent estimates of SWARF, and can be used as a validation tool for studies that attempt to model the role of aerosols on climate. Copyright 2002 by the American Geophysical Union."
"35464731600;7003478309;55725404100;7005399437;","Remote sensing of non-aerosol absorption in cloud free atmosphere",2002,"10.1029/2001GL014399","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037107292&doi=10.1029%2f2001GL014399&partnerID=40&md5=1b533ac93bd4016c8cfad5e2a9a541b8","Knowledge of the absorption of sunlight by atmospheric gases, aerosols and clouds is key to understanding climate and its variation. Several studies suggested that clouds absorb sunlight significantly more than what models predict. Other studies suggested that the anomalous absorption is present in cloud-free conditions. Here we measure absorption in cloud free atmosphere using the Aerosol Robotic Network (AERONET). Measurements of attenuation of direct sunlight are used to derive extinction optical thickness and sky measurements to derive scattering optical thickness, Residual extinction for zero scattering, cannot be caused by aerosols or known gases and would be associated with the cloud free absorption anomaly. The anomalous absorption, if exists, is assumed not to correlate with the presence of aerosol. The measurements, taken for several years in locations around the world, show that in the atmospheric windows 0.44, 0.67, 0.87 and 1.02 μm the only significant absorbers in cloud free atmosphere is aerosol and ozone. Non-aerosol absorption, defined as spectrally independent or smoothly variable, was found to have an optical thickness smaller than 0.002 ± 0.003, thereby, absorption of sunlight smaller than 1W/m2. Copyright 2002 by the American Geophysical Union."
"7201425334;7102567936;","Tropical tropospheric temperature variations caused by ENSO and their influence on the remote tropical climate",2002,"10.1175/1520-0442(2002)015<2616:TTTVCB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037106794&doi=10.1175%2f1520-0442%282002%29015%3c2616%3aTTTVCB%3e2.0.CO%3b2&partnerID=40&md5=871398270a7df9c12a1629f0e9dcf137","The warming of the entire tropical free troposphere in response to El Niño is well established, and suggests a tropical mechanism for the El Niño-Southern Oscillation (ENSO) teleconnection. The potential impact of this warming on remote tropical climates is examined through investigating the adjustment of a single-column model to imposed tropospheric temperature variations, assuming that ENSO controls interannual tropospheric temperature variations at all tropical locations. The column model predicts the impact of these variations in three typical tropical climate states (precipitation > evaporation: precipitation < evaporation: no convection) over a slab mixed layer ocean. Model precipitation and sea surface temperature (SST) respond significantly to the imposed tropospheric forcing in the first two climate states. Their amplitude and phase are sensitive to the imposed mixed layer depth, with the nature of the response depending on how fast the ocean adjusts to imposed tropospheric temperature forcing. For larger mixed layer depth, the SST lags the tropospheric temperature by a longer time, allowing greater disequilibrium between atmosphere and ocean. This causes larger surface flux variations, which drive larger precipitation variations. Moist convective processes are responsible for communicating the tropospheric temperature signal to the surface in this model. Preliminary observational analysis suggests that the above mechanism may be applicable to interpreting interannual climate variability in the remote Tropics. In particular, it offers a simple explanation for the gross spatial structure of the observed surface temperature response to ENSO, including the response over land and the lack thereof over the southeast tropical Atlantic and southeast tropical Indian Oceans. The mechanism predicts that the air-sea humidity difference variation is a driver of ENSO-related remote tropical surface temperature variability, an addition to wind speed and cloudiness variations that previous studies have shown to be important."
"7403318365;57193132723;","Effects of cloud parameterization on the simulation of climate changes in the GISS GCM. Part II: Sea surface temperature and cloud feedbacks",2002,"10.1175/1520-0442(2002)015<2491:EOCPOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036748172&doi=10.1175%2f1520-0442%282002%29015%3c2491%3aEOCPOT%3e2.0.CO%3b2&partnerID=40&md5=8562ade099b35747874e955e78ea6e95","The influence of the sea surface temperature distribution on cloud feedbacks is studied by making two sets of doubled CO2 experiments with the Goddard Institute for Space Studies (GISS) GCM at 4° latitude 5° longitude resolution. One set uses Q fluxes obtained by prescribing observed sea surface temperatures (MODELII'), and the other set uses Q fluxes obtained by prescribing the simulated sea surface temperature of a coupled ocean-atmosphere model (MODELIIO). The global and annual mean surface air temperature change (Δ Ts) obtained in MODELII' is reduced from 4.11° to 3.02°C in MODELIIO. This reduced sensitivity, aside from reduced sea ice/snow-albedo feedback, is mainly due to cloud feedback that becomes nearly neutral in MODELIIO. Furthermore, the negative effect on climate sensitivity of anvil clouds of large optical thickness identified by Yao and Del Genio changes its sign in MODELIIO primarily due to sharply reduced increases of cloud water in the tropical upper troposphere. Colder tropical sea surface temperature in MODELIIO results in weaker deep convective activity and a more humid lower atmosphere in the warmer climate relative to MODELIIO', which then removes the negative feedback of anvil clouds and sharply reduces the positive feedback of low clouds. However, an overall positive cloud optical thickness feedback is still maintained in MODELIIO. It is suggested that the atmospheric climate sensitivity, partially due to changes in cloud feedbacks, may be significantly different for climate changes associated with different patterns of sea surface temperature change, as for example in warm versus cold paleoclimate epochs. Likewise, the climate sensitivity in coupled atmosphere-ocean models is also likely to be significantly different from the results obtained in Q-flux models due to the different simulations of sea surface temperature patterns in each type of model."
"7003491570;7404325680;","Arctic sea ice, cloud, water, and lead classification using neural networks and 1.6-μm data",2002,"10.1109/TGRS.2002.803728","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036763017&doi=10.1109%2fTGRS.2002.803728&partnerID=40&md5=5d454e212896b11d14f32b6fef40be9c","Polar sea ice plays a critical role in regulating the global climate. Seasonal variation in sea ice extent, however, coupled with the difficulties associated with in situ observations of polar sea ice, makes remote sensing the only practical way to estimate this important climatic variable on the space and time scales required. Unfortunately, accurate retrieval of sea ice extent from satellite data is a difficult task. Sea ice and high cold clouds have similar visible reflectance, but some other types of clouds can appear darker than sea ice. Moreover, strong atmospheric inversions and isothermal structures, both common in winter at some polar locations, further complicate the classification. This paper uses a combination of feed-forward neural networks and 1.6-μm data from the new Chinese Fengyun-1C satellite to mitigate these difficulties. The 1.6-μm data are especially useful for detecting illuminated water clouds in polar regions because 1) at 1.6 μm, the reflectance of water droplets is significantly higher than that of snow or ice and 2) 1.6-μm data are unaffected by atmospheric inversions. Validation data confirm the accuracy of the new classification technique. Application to other sensors with 1.6-μm capabilities also is discussed."
"16507288800;7202899322;8048183500;","NOAA's multi-sensor fire detection program using environmental satellites",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036709918&partnerID=40&md5=9ef5ab00c48207202bb2b721b63cb980","Biomass burning has tremendous impact on the Earth's ecosystems and climate, for it drastically alters the landscape and biologic structure, and emits large amounts of greenhouse gases and aerosol particles. Smoke aerosols may interact with cloud droplets and alter considerably the earth's radiation budget. Remote sensing is the most efficient and economical means of monitoring fires over large areas on a routine basis, despite that it suffers from various limitations. Satellite observations can provide timely information on both fire development and fire damage following fire. Remote sensing of fires also has the potential to help authorities make decisions regarding fire fighting and reducing the impact of fires on the population. The capability to detect fires from space using environmental satellites has long been appreciated, and investigations at National Environmental Satellite, Data and Information Service (NESDIS) have been conducted for over twenty years. Matson and Dozier (1981) demonstrated the ability to detect and characterize sub-pixel resolution fires. Matson et al. (1984) correlated satellite derived hot spots with confirmed ground observations, and Matson et al. (1987) presented a summary of satellite detection capabilities. Satellite images of fires and smoke have been produced routinely within the Satellite Services Division (SSD) since then to demonstrate detection capabilities. This smoke and fire product relied heavily on satellite imagery from NOAA's Geostationary Operational Environmental Satellite (GOES) series. This platform allows for at least half-hourly detection of these hazards over the U.S. The frequent temporal updates allow for detection of fairly short lived fires (up to a couple of hours) as well as fires that have intermittent cloud cover over them. The primary satellite bands that are employed are in the visible wavelengths for smoke detection and 3.9 microns for sensing fires. The resolution for GOES is 1km at satellite subpoint for the visible channel and 4 km at subpoint for the 3.9 micron channel (and all other thermal bands). However, resolution gradually decreases as zenith angle increases such that the effective resolution over large parts of the US is actually 5 or 6 km."
"6602557903;55673012400;36658166000;35270245200;","Surface ozone at four remote island sites and the preliminary assessment of the exceedances of its critical level in Japan",2002,"10.1016/S1352-2310(02)00339-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036707943&doi=10.1016%2fS1352-2310%2802%2900339-4&partnerID=40&md5=869efa4eb64e6b4c099f45d2a4a9b81c","Analysis of the recent surface ozone data at four remote islands (Rishiri, Oki, Okinawa, and Ogasawara) in Japan indicates that East Asian anthropogenic emissions significantly influence the boundary layer ozone in Japan. Due to these regional-scale emissions, an increase of ozone concentration is observed during fall, winter, and spring when anthropogenically enhanced continental air masses from Siberia/Eurasia arrive at the sites. The O3 concentrations in the 'regionally polluted' continental outflow among sites are as high as 41-46ppb in winter and 54-61ppb in spring. Meanwhile, marine air masses from the Pacific Ocean show as low as 13-14ppb of O3 at Okinawa and Ogasawara in summer but higher O3 concentrations, 24-27ppb, are observed at Oki and Rishiri due to the additional pollution mainly from Japan mainland. The preliminary analysis of the exceedances of ozone critical level using AOT40 and SUM06 exposure indices indicates that the O3 threshold were exceeded variously among sites and years. The highest AOT40 and SUM06 were observed at Oki in central Japan where the critical levels are distinctly exceeded. In the other years, the O3 exposures at Oki, Okinawa, and Rishiri are about or slightly higher than the critical levels. The potential risk of crop yields reduction from high level of O3 exposure in Japan might not be a serious issue during 1990s and at present because the traditional growing season in Japan are during the low O3 period in summer. However, increases of anthropogenic emission in East Asia could aggravate the situation in the very near future. Copyright © 2002 Elsevier Science Ltd."
"6603064238;56247884400;7006684170;","Navidad development in the southern Bay of Biscay: Climate change and swoddy structure from remote sensing and in situ measurements",2002,"10.1029/2001jc001012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037104884&doi=10.1029%2f2001jc001012&partnerID=40&md5=4fc0c77d9780c1bee2828e9b241098ad","The warm water extension of the Iberian Poleward Current off northern Spain (""Navidad"") was examined in the advanced very high resolution radiometer (AVHRR) satellite archive (1979-2000) and in a time series of January sea surface temperatures. Winter warming in the southern Bay of Biscay during Navidad years was correlated with low values of the North Atlantic Oscillation (NAO) Index for the preceding months (November-December). Exceptional Navidad development and winter warming were observed during January 1990, January 1996, and January 1998, and extensive measurements were gathered for these 3 years. The Eastern Boundary poleward warming was found to extend from Portugal to Norway in exceptional Navidad years. The long-term changes of SST in the Navidad region (1967-2000) were analyzed in the frame of the decadal variation for the Celtic shelf (1890-2000), which showed an increase of 1°C over the century. During January 1990 and January 1996, cloud-free images of Navidad showed a pronounced production of slope water oceanic eddies (swoddies) in the SE corner of the Bay of Biscay. The small-scale properties of one of these swoddies (F90) were analyzed during summer from measurements at sea (RRS Discovery 193 cruise; July 1990). SeaSoar sections showed the physical structure of the swoddy core. The distribution and abundance of chlorophyll a associated with the swoddy was determined. It is shown that a swoddy has a higher chlorophyll a maximum in the seasonal thermocline than associated cyclones. Simultaneous satellite observations of the sensors AVHRR, Sea-viewing Wide Field-of- view Sensor (SeaWiFS), and altimeter (combined TOPEX/Poseidon/ERS-2 data) were used to analyze the remote sensing properties of three summer swoddy-like eddies during August 1998. The summer SeaWiFS chlorophyll a concentration at the center of the eddy near 45.5°N, 6°W (AE6) was appraised against a time series (September 1997 to April 2001) of SeaWiFS chlorophyll a concentration representative of a central region of the Bay of Biscay."
"7203069651;6604008249;","Tectonic controls on greenhouse gas flux to the Paleogene atmosphere from the Gulf of Alaska accretionary prism",2002,"10.1130/0091-7613(2002)030<0547:TCOGGF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879886909&doi=10.1130%2f0091-7613%282002%29030%3c0547%3aTCOGGF%3e2.0.CO%3b2&partnerID=40&md5=75298d2c0102a8ebd4c509f1f90504b4","The late Paleocene to early Eocene (ca. 61-56 Ma) was a period of long-term global warming, perhaps the warmest in the Cenozoic. Recent modeling suggests that methane loading of the atmosphere, and related development of polar stratospheric clouds, could have been an important forcing mechanism for this period of warm climate. The Gulf of Alaska accretionary prism contained ~6 × 106 km3 of siliciclastic sediments deposited in trench and slope settings along Alaska's Maastrichtian and Paleogene continental margin. These sediments underwent complex deformation, accretion, and unusual high heat flow soon after deposition. Accretion processes thermally overmatured the sediments during a time that overlaps the 61-56 Ma period of long-term global warming. Assuming a modest average organic carbon content of 0.3 wt% in these sediments, an estimated 8.35 × 1015 kg of methane were generated in the accretionary prism over an ~5 m.y. period. This methane was not effectively trapped, and migration pathways to the atmosphere were developed through complexly deformed and emergent continental borderlands. The Gulf of Alaska accretionary prism is a possible source of the atmospheric methane needed to force Paleocene and early Eocene global warming and an example of how tectonic processes can significantly recycle carbon from the geosphere."
"7402989545;24511929800;","Simulation of the East Asian summer monsoon using a variable resolution atmospheric GCM",2002,"10.1007/s00382-001-0214-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036315324&doi=10.1007%2fs00382-001-0214-8&partnerID=40&md5=7ae90b6972656e49c529d4143522be31","The East Asia summer monsoon (EASM) is simulated with a variable resolution global atmospheric general circulation model (GCM) developed at the Laboratoire de Météorologie Dynamique, France. The version used has a local zoom centered on China. This study validates the model's capability in reproducing the fundamental features of the EASM. The monsoon behaviors over East Asia revealed by the ECMWF reanalysis data are also addressed systematically, providing as observational evidence. The mean state of the EASM is generally portrayed well in the model, including the large-scale monsoon airflows, the monsoonal meridional circulation, the cross-equatorial low-level jets, the monsoon trough in the South China Sea, the surface cold high in Australia, and the upper-level northeasterly return flow. While the performance of simulating large-scale monsoonal climate is encouraging, the model's main deficiency lies in the rainfall. The marked rainbelt observed along the Yangtze River Valley is missed in the simulation. This is due to the weakly reproduced monsoonal components in essence and is directly related to the weak western Pacific subtropical high, which leads to a fragile subtropical southwest monsoon on its western flank and results in a weaker convergence of the southwest monsoon flow with the midlatitude westerlies. The excessively westward extension of the high, together with the distorted Indian low, also makes the contribution of the tropical southwest monsoon to the moisture convergence over the Yangtze River Valley too weak in the model. The insufficient plateau heating and the resulting weak landsea thermal contrast are responsible for the weakly reproduced monsoon. It is the deficiency of the model in handling the low-level cloud cover over the plateau rather than the horizontal resolution and the associated depiction of plateau topography that results in the insufficient plateau heating. Comparison with the simulation employing regular coarser mesh model reveals that the local zoom technique improves, in a general manner, the EASM simulation."
"36927572900;6603697954;","Remote sensing of Antarctic clouds with infrared and passive microwave sensors",2002,"10.1127/0941-2948/2002/0011-0021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036320369&doi=10.1127%2f0941-2948%2f2002%2f0011-0021&partnerID=40&md5=9575ddcfd17239cf03d50d7ede0b127c","The importance of the polar regions and of clouds for the global climate is widely recognized. But clouds in polar regions are difficult to detect in infrared satellite images because the brightness temperatures of the surface and clouds are very similar. Sensors operating at visible wavelengths are less suited because they need daylight and can therefore not operate in the polar night. Three methods have been developed and tested to retrieve clouds over polar regions. Only data of infrared and passive microwave sensors of the DMSP satellites are used, the algorithms are therefore independent of the daylight and can also be applied in the polar night. The first approach classifies single infrared images of the sensor OLS over the Weddell Sea into 'cloud', 'sea ice' and 'open water'. First, the images are subdivided into segments. For each segment, four texture parameters are evaluated. The algorithm uses a Learning Vector Classification Neural Network. The trained network classifies test data from March 1992 with an accuracy of 88%. Inclusion of SSM/I sea ice information improves this result to 91%. The second, qualitative method detects nonstratiform clouds over the Antarctic continent using differences of nearly simultaneous infrared images collected by different DMSP spacecraft. If observed under different incidence angles, nonstratiform clouds show different infrared brightness temperatures. Validations with visible data and with data of the passive microwave sounder SSM/T2 also onboard the DMSP platforms show good agreement. Thirdly, a multi sensor approach is outlined including the first two methods and in addition the SSM/I-derived atmospheric parameters total water vapor, liquid water path (LWP) and the cloud signature, a recently proposed quantity for cloud characterization over sea ice. The cloud features high/middle/low, stratiform/nonstratiform and thickness (expressed as LWP or cloud signature) can be used for cloud description. The method is demonstrated in a case study with data recorded on the R/V Polarstern in the Weddell Sea in April 1998."
"6506837510;7007108728;55087038900;6603734019;","Parameterization of effective ice particle size for high-latitude clouds",2002,"10.1002/joc.774","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036692274&doi=10.1002%2fjoc.774&partnerID=40&md5=02c5e50ad6e9a6d15585f2e749889b8a","A parameterization has been developed for mean effective size Dge in terms of ice water content (IWC) and temperature using in situ measurements of ice crystal spectra, cloud particle shapes and particle cross-sectional area A from four research projects conducted in latitudes north of 45°N. The cloud microphysical measurements were made using PMS 2D optical probes, a PMS forward scattering spectrometer probe (FSSP), and Nevzorov total water and liquid water content probes. The IWCs derived from particle spectra using three different methods were compared with IWC measured with the Nevzorov probe (IWCNev). The contribution of small particles to the total mass was estimated by integrating a gamma distribution function that was fitted to match the measured FSSP concentrations. The Dge was calculated from the derived IWC and total cross-sectional area per unit volume Ac. This analysis indicates that there are significant differences among the schemes used to derive the IWC. It was found that the IWC derived based on the Cunningham scheme and IWCNev have the highest correlation: r2 = 0.78. After considering small particles, the derived IWC almost matched the IWCNev. The average estimated contribution of small particles to the Ac was 43%. The average estimated contribution of small particles to the total IWC, however, was 20%. Since Dge is directly proportional to the ratio IWC/Ac, the addition of small particles reduced the derived Dge considerably. The largest changes in Dge associated with small particles, however, occur at the coldest temperature and at low IWC, reaching up to 45% for temperatures less than -25°C. Generally, Dge and IWC increase with increasing temperature. Good agreement between the parameterized Dge and derived Dge from measurements were found when small particles were included. Copyright © 2002 Royal Meteorological Society."
"51360903200;7005890514;","The roles of radiation and dynamical processes in the El Niño-like response to global warming",2002,"10.1007/s00382-002-0244-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036692364&doi=10.1007%2fs00382-002-0244-x&partnerID=40&md5=37f65035cf60155886721c697bf7d9e0","The current understanding of ENSO does not foreshadow how it might change as a consequence of global warming due to an increase in atmospheric greenhouse gas (GHG) concentration. A number of global coupled climate models simulate a ""mean"" El Niño-like change in tropical Pacific temperatures, precipitation, and winds but at least one model exhibits a La Niña-like pattern and others a more or less homogeneous warming in the tropics with little of either pattern. The mechanisms leading to a mean positive El Niño-like pattern (PEP) are studied in simulations with the Canadian Centre for Climate Modeling and Analysis (CCCma) coupled general circulation model. The changes associated with the PEP are compared with, and are shown to closely resemble, those observed for the positive El Niño phase of the ENSO oscillation in the current climate including the anomalies in SST, precipitation and atmospheric circulation, the changes of vertically integrated energy and heat transports in the atmosphere, and changes in the sign and magnitude of radiative energy balance terms. The PEP in the model is supported by changes in oceanic heat transport and surface longwave radiative flux in the face of solar radiative flux and evaporative flux changes which act to damp it away. There is negative cloud-radiation feedback associated with the PEP, as with the observed El Niño. Negative cloud feedback by itself does not, therefore, preclude the existence of a PEP response to GHG forcing. The climatological PEP does not exhibit an oceanic export of energy from the tropical Pacific, as inferred for the regular El Niño event, but rather an oceanic import of energy. Nevertheless the PEP provides an effective means of regulating climate warming and the energy budget in the tropical Pacific which is accomplished through energy transports out of the region by the atmosphere. The PEP is seen as a more or less straightforward manifestation of the feedback mechanism proposed by Bjerknes and as a physically plausible response to GHG-induced climate warming."
"6603043427;56187834500;","Temperature, light, and the dimethylsulfoniopropionate (DMSP) content of Emiliania huxleyi (Prymnesiophyceae)",2002,"10.1016/S1385-1101(02)00134-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036689269&doi=10.1016%2fS1385-1101%2802%2900134-X&partnerID=40&md5=bb67ce2484ff59e28e0d8e8486cb9bb5","The precursor of the volatile S-compound dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), is produced by marine microalgae, notably by Prymnesiophyceae. The production of DMSP by an axenic isolate of Emiliania huxleyi (Lohm.) Hay et Mohler under different temperature and light conditions was studied as a first step towards understanding the role of DMSP-producing algae in climate regulation. Both light and temperature affected growth rate and cell size in batch cultures, but the concentration of DMSP in the cells was dependent on temperature only: at low temperature DMSP accumulated. This physiological response, assumed to be characteristic of DMSP-producing microalgae in general, is in line with the correlation that has been found between elevated concentrations of the DMS oxidation product MSA in ice core slices corresponding with low sea surface temperatures. Apparently, DMS does not play the role in climate regulation formulated in the CLAW hypothesis that proposes a feedback mechanism in which elevated temperatures lead to an increase in albedo via DMS-derived cloud condensation nuclei. © 2002 Elsevier Science B.V. All rights reserved."
"7005365571;6603809220;6602579613;","The atmospheric boundary layer in the CSIRO global climate model: Simulations versus observations",2002,"10.1007/s00382-002-0233-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036689281&doi=10.1007%2fs00382-002-0233-0&partnerID=40&md5=3670478e1972516cf9f6a00732cc84cd","A 5-year simulation of the atmospheric boundary layer in the CSIRO global climate model (GCM) is compared with detailed boundary-layer observations at six locations, two over the ocean and four over land. Field observations, in the form of surface fluxes and vertical profiles of wind, temperature and humidity, are generally available for each hour over periods of one month or more in a single year. GCM simulations are for specific months corresponding to the field observations, for each of five years. At three of the four land sites (two in Australia, one in south-eastern France), modelled rainfall was close to the observed climatological values, but was significantly in deficit at the fourth (Kansas, USA). Observed rainfall during the field expeditions was close to climatology at all four sites. At the Kansas site, modelled screen temperatures (Tsc), diurnal temperature amplitude and sensible heat flux (H) were significantly higher than observed, with modelled evaporation (E) much lower. At the other three land sites, there is excellent correspondence between the diurnal amplitude and phase absolute values of each variable (Tsc, H, E). Mean monthly vertical profiles for specific times of the day show strong similarities: over land and ocean in vertical shape and absolute values of variables, and in the mixed-layer and nocturnal-inversion depths (over land) and the height of the elevated inversion or height of the cloud layer (over the sea). Of special interest is the presence climatologically of early morning humidity inversions related to dewfall and of noctural low-level jets; such features are found in the GCM simulations. The observed day-to-day variability in vertical structure is captured well in the model for most sites, including, over a whole month, the temperature range at all levels in the boundary layer, and the mix of shallow and deep mixed layers. Weaknesses or unrealistic structure include the following, (a) unrealistic model mixed-layer temperature profiles over land in clear skies, related to use of a simple local first-order turbulence closure, (b) a tendency to overpredict cloud liquid water near the surface."
"6603809220;57203053317;","Tropical rainfall trends and the indirect aerosol effect",2002,"10.1175/1520-0442(2002)015<2103:TRTATI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036693782&doi=10.1175%2f1520-0442%282002%29015%3c2103%3aTRTATI%3e2.0.CO%3b2&partnerID=40&md5=315e408832cfde467534ce133f92dbe8","An atmospheric global climate model coupled to a mixed layer ocean model is used to study changes in tropical rainfall due to the indirect effects of anthropogenic sulfate aerosol. The model is run to equilibrium for present-day (PD) and preindustrial (PI) sulfur emission scenarios. As in two other recent studies, the model generally gives a southward shift of tropical rainfall in the PD run relative to the PI run. This is largely due to a hemispheric asymmetry in the reduction of sea surface temperature (SST) induced by the perturbation of cloud albedo and lifetime. Observed precipitation trends over land for the period 1900-98 show a complex pattern in the Tropics, but when zonally averaged, a southward shift similar to (but weaker than) the modeled shift is clearly evident. The zonally averaged tropical trends are significant at the 5% level in several latitude bands. The modeled present-day hemispheric contrast in cloud droplet effective radius (which affects cloud albedo) is well supported by one long-term satellite retrieval, but not by another. A third satellite retrieval, which only covers an 8-month period, does show a marked hemispheric contrast in effective radius. Both in the modeled changes and the observed trends, a prominent feature is the drying of the Sahel in North Africa. Modeled dynamical changes in this region are similar to observed changes that have been associated with Sahelian drought. Previous work has identified a near-global, quasi-hemispheric pattern of contrasting SST anomalies (cool in the Northern Hemisphere and warm in the Southern Hemisphere) associated with dry conditions in the Sahel. The present results, combined with this earlier finding, suggest that the indirect effects of anthropogenic sulfate may have contributed to the Sahelian drying trend. More generally, it is concluded that spatially varying aerosol-related forcing (both direct and indirect) can substantially alter low-latitude circulation and rainfall."
"36784945400;56424145700;","The time-space structure of the Asian-Pacific summer monsoon: A fast annual cycle view",2002,"10.1175/1520-0442(2002)015<2001:ttssot>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036694281&doi=10.1175%2f1520-0442%282002%29015%3c2001%3attssot%3e2.0.co%3b2&partnerID=40&md5=ca66498d8156b8507b6265ce9ca17429","Despite the seemingly intricate and multifold time-space structure of the mean Asian-Pacific summer monsoon (APSM), its complexity can be greatly reduced once the significance of fast annual cycles has been recognized and put into perspective. The APSM climatology is characterized by a slowly evolving seasonal transition (slow annual cycle) superposed by pronounced singularities in the intraseasonal timescale, termed the ""fast annual cycle"" in this study. The fast annual cycles show nonrepetitive features from one episode to another, which are often divided by abrupt change events. The APSM fast annual cycles are composed mainly of two monsoon outbreaks, each marking a distinctive dry-wet cycle. The first cycle spans from the middle of May to early July and the second cycle from late July to early September. When the first cycle reaches its peak in mid-June, a slingshot-like convection zone, described as the grand-onset pattern, rules an area from the Arabian Sea to the Indochina Peninsula then bifurcates into a mei-yu branch and a tropical rain belt in the lower western North Pacific. After a brief recess during 20-29 July, the APSM harbors another rain surge in mid-August. This time a giant oceanic cyclone intensifies over the western North Pacific (around 20°N, 140°E); thus the rainy regime jumps 10°-15° north of the previous rain belt. This ocean monsoon gyre incubates numerous tropical cyclones. Meanwhile, the convection zone of the Indian monsoon intensifies and extends well into the subcontinent interior. From the first to second cycle the major convection center has shifted from the adjacent seas in the northern Indian Ocean to the open ocean east of the Philippine Islands. The major cloud movement also switches from a northeastward direction in the Idian Ocean to a northwestward direction over the western North Pacific. The two monsoon cycles turn out to be a global phenomenon. This can be shown by the coherent seasonal migration of upper-level subtropical ridgelines in the Northern Hemisphere. During the first cylce all the ridgelines migrate northward rapidly, a sign that the major circulation systems of boreal summer go through a developing stage. After 20-29 July, they reach a quasi steady state, a state in which all the ridgelines stand still near their northern rim throughout the entire second cycle. A reconstructed fast annual cycle based on four leading empirical orthogonal function modes is capable of reproducing most fine details of the APSM climatology, suggesting that the subseasonal changes of the mean APSM possess a limited number of degrees of freedom. A monsoon calendar designed on the basis of fast annual cycles (FACs) gives a concise description of the APSM climatology and provides benchmarks for validating climate model simulations."
"35600074800;7003740015;","A pseudo-Lagrangian study of the sulfur budget in the remote Arctic marine boundary layer",2002,"10.1034/j.1600-0889.2002.01247.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036299722&doi=10.1034%2fj.1600-0889.2002.01247.x&partnerID=40&md5=6b1f60e7dab3470da3f5f3f27dd6bc8c","The atmospheric sulfur cycle of the remote Arctic marine boundary layer is studied using trajectories and measurements of sulfur compounds from the International Arctic Ocean Expedition 1991, along with a pseudo-Lagrangian approach and an analytical model. The dimethyl sulfide [DMS(g)] turnover time was 59A+18-9 h. Only 25+11-9% of DMS(g) followed reaction paths to sulfur dioxide [SO2(g)], sub-micrometre aerosol non-seasalt sulfate (nss-SO2-4) or methane sulfonate (MSA). During the first 3 d of transport over the pack ice, fog deposition and drizzle resulted in short turnover times; 16+8-6 h for SO2(g), 18+4-4 h for MSA and 18+2-3 h for nss-SO42-4. Therefore, DMS(g) will, owing to its origin along or south of the ice edge and longer turnover time, survive the original sub-micrometre sulfur aerosol mass and gradually replace it with new biogenic sulfur aerosol mass. The advection of DMS(g) along with heat and moisture will influence the clouds and fogs over the Arctic pack ice through the formation of cloud condensation nuclei (CCN). If the pack ice cover were to decrease owing to a climate change, the total Arctic Ocean DMS production would change, and potentially there could be an ice-DMS-cloud-albedo climate feedback effect, but it would be accompanied by changes in the fog aerosol sink."
"7201443624;7004034323;7003976079;","Influence of dynamics on the changes in tropical cloud radiative forcing during the 1998 El Niño",2002,"10.1175/1520-0442(2002)015<1979:IODOTC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037099060&doi=10.1175%2f1520-0442%282002%29015%3c1979%3aIODOTC%3e2.0.CO%3b2&partnerID=40&md5=70117a7329ae74e74082a41a4e83e10d","Satellite measurements of the radiation budget and data from the U.S. National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis are used to investigate the links between anomalous cloud radiative forcing over the tropical west Pacific warm pool and the tropical dynamics and sea surface temperature (SST) distribution during 1998. The ratio, N, of the shortwave cloud forcing (SWCF) to longwave cloud forcing (LWCF) (N = -SWCF/LWCF) is used to infer information on cloud altitude. A higher than average N during 1998 appears to be related to two separate phenomena. First, dynamic regime-dependent changes explain high values of N (associated with low cloud altitude) for small magnitudes of SWCF and LWCF (low cloud fraction), which reflect the unusual occurrence of mean subsiding motion over the tropical west Pacific during 1998, associated with the anomalous SST distribution. Second, Tropics-wide long-term changes in the spatial-mean cloud forcing, independent of dynamic regime, explain the higher values of N during both 1998 and in 1994/95. The changes in dynamic regime and their anomalous structure in 1998 are well simulated by version HadAM3 of the Hadley Centre climate model, forced by the observed SSTs. However, the LWCF and SWCF are poorly simulated, as are the interannual changes in N. It is argued that improved representation of LWCF and SWCF and their dependence on dynamical forcing are required before the cloud feedbacks simulated by climate models can be trusted."
"7202048299;7006705919;","Parameterizing vertically coherent cloud distributions",2002,"10.1175/1520-0469(2002)059<2165:PVCCD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037099096&doi=10.1175%2f1520-0469%282002%29059%3c2165%3aPVCCD%3e2.0.CO%3b2&partnerID=40&md5=5558cdb31ef358f461b0388617503044","A parameterization for specifying subgrid-scale cloud distributions in atmospheric models is developed. The fractional area of a grid-scale column in which clouds from two levels overlap (i.e., the cloud overlap probability) is described in terms of the correlation between horizontal cloudiness functions in the two levels. Cloud distributions that are useful for radiative transfer and cloud microphysical calculations are then determined from cloud fraction at individual model levels and a decorrelation depth. All pair-wise overlap probabilities among cloudy levels are obtained from the cloudiness correlations. However, those probabilities can overconstrain the determination of the cloud distribution. It is found that cloud fraction in each level along with the overlap probabilities among nearest neighbor cloudy levels is sufficient to specify the full cloud distribution. The parameterization has both practical and interpretative advantages over existing parameterizations. The parameterized cloud fields are consistent with physically meaningful distributions at arbitrary vertical resolution. In particular, bulk properties of the distribution, such as total cloud fraction and radiative fluxes calculated from it, approach asymptotic values as the vertical resolution increases. Those values are nearly obtained once the cloud distribution is resolved; that is, if the thickness of cloudy levels is less than one half of the decorrelation depth. Furthermore, the decorrelation depth can, in principle, be specified as a function of space and time, which allows one to construct a wide range of cloud distributions from any given vertical profile of cloud fraction. The parameterization is combined with radiative transfer calculations to examine the sensitivity of radiative fluxes to changes of the decorrelation depth. Calculations using idealized cloud distributions display strong sensitivities (∼50 W m-2) to changes of decorrelation depth. Those sensitivities arise primarily from the sensitivity of total cloud fraction to that parameter. Radiative fluxes calculated from a version of the National Center for Atmospheric Research Community Climate Model (CCM) show only a small sensitivity. The reason for this small sensitivity is traced to the propensity of CCM to produce overcast conditions within individual model levels. Thus, in order for the parameterization to be fully useful, it is necessary that other cloud parameterizations in the atmospheric model attain a threshold of realism."
"57203598636;57203140160;6603552038;6602784254;","Numerical uncertainties in simulation of reversible isentropic processes and entropy conservation: Part II",2002,"10.1175/1520-0442(2002)015<1777:NUISOR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037098979&doi=10.1175%2f1520-0442%282002%29015%3c1777%3aNUISOR%3e2.0.CO%3b2&partnerID=40&md5=f073e7dbc18e1cee46adb4356c96d0d4","The objectives of this study are 1) to provide the framework for an in-depth statistical analysis of the numerical uncertainties in the simulation of conservation of entropy, potential vorticity, and like properties under appropriate modeling constraints, and 2) to illustrate the discriminating nature of the analysis in an application that isolates internal numerical inaccuracies in the simulation of reversible atmospheric processes. In an earlier study the authors studied the pure error sum of squares function as a quadratic measure of uncertainties by summing the squared differences between equivalent potential temperature as simulated by the nonlinear governing equations for mass, energy, water vapor, and cloud water and its counterpart simulated as a trace constituent. Within the experimental design to examine a model's capabilities to conserve the moist entropy, the continuum equations demand that the differences between equivalent potential temperature θe, and proxy equivalent potential temperature tθe, vanish at all discrete model information points throughout the 10-day simulation. The differences that develop provide a measure of numerical inaccuracies in the simulation of reversibility. In this extension of the earlier study, the first consideration is to examine zonal-vertical cross sections of the differences. relative frequency distributions of the differences, and the vertical structure of systematic differences. Subsequently, through an analysis of variance, the sum of squares is partitioned into three components: the squared deviations of differences from an area mean difference, the square of the deviation of the mean difference from the global mean difference, and the square of the global mean difference. In the situation where biases vanish in all three components, a theoretical development based on the uniqueness of a distribution with its moment-generating function suggests that the nearer the empirical relative frequency distribution of pure error differences is to the classical triangular distribution of the differences of two random variates, the closer the model's simulation is to the optimum accuracy feasible in ensuring reversibility and appropriate conservation of moist entropy. A final consideration is to place the random and systematic components of differences within a probability perspective in which the normal distribution is utilized to assess whether the magnitude of the average difference exceeds that expected to develop from the presence of the random component. The focus of the application in this study assesses the capabilities of several models to simulate the conservation of moist entropy and reversibility of moist-adiabatic processes over a period of 10 days. The assessment includes four different versions of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM) and the University of Wisconsin (UW) hybrid isentropic-sigma (θ-σ) model. The assessment from the 10-day simulations focuses on the temporal evolution of the global sum of squares of the differences of equivalent potential temperature and its trace and the three components. In the case of all models expressed in sigma coordinates, the global sum of squares as simulated exceeds the global sum of squares from the UW θ-σ model. The partitioning into three components of variance revealed different structures of average differences resulting from errors in vertical exchange, and also different magnitudes of the random component among the CCM models. In contrast, the component sum of squares in the UW θ-σ model simulation was minimal, except for small global and area average differences stemming from transport across the interface between the isentropic and sigma domains of the model in the low troposphere. The empirical relative frequency distribution for the pure error differences in the UW θ-σ model tends to equilibrate and be triangular in form as would be expected from statistical theory in which the random variate is given by the differences of two variates, each of which is drawn from a uniform distribution of random errors. In conclusion, the combination of the methods developed in the earlier study and this paper provides a robust strategy for the global assessments of numerical accuracies in simulating reversibility within weather and climate predictions throughout the model domain globally and also regionally."
"7003582587;56213029000;7401584839;","The impact of horizontal resolution on the simulations of convective development over land",2002,"10.1256/003590002320603511","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036652496&doi=10.1256%2f003590002320603511&partnerID=40&md5=3dbb740a1ca266eed85db3a23c685dc9","Cloud-resolving models (CRMs) can be used to provide subgrid information for use in improving the representation of the development of convection in large-scale models. However, for the CRM to be of value, it must itself give an accurate representation of the processes involved. In the work presented here we focus on the development of convection in simulations of both shallow and deep convection over land and consider sensitivity to the horizontal resolution in a CRM. In both shallow and deep cases it is found to be necessary to provide adequate resolution of the sub-cloud layer in order to obtain a satisfactory representation of the transport of moisture from the sub-cloud layer into the free troposphere. Typically this requires the horizontal grid spacings to be no coarser than around one quarter of the sub-cloud layer depth. Poorer resolution with the present model leads to significant delays in the development of convection. While a more sophisticated subgrid scheme could reduce the sensitivity to resolution, the work here has shown the resolution required to explicitly resolve the key processes. Using this improved resolution may be one technique for reducing the discrepancies between some model results and observations reported in earlier studies."
"6602519468;6701774129;7102793930;","Study of hail density parametrizations",2002,"10.1256/00359000260247309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036649768&doi=10.1256%2f00359000260247309&partnerID=40&md5=357f190710c49f11c0041de7b130ab4b","One aspect of hailstone growth that has received attention over the last twenty years is the importance of low-density riming growth in hail. Density is an important parameter in riming growth because it regulates hail size and is also involved in other atmospheric processes, like crystal multiplication, charge transfer, etc. New numerical dynamic and cinematic models take into account the variability of density with growth parameters (such as size of cloud droplets, impact velocity and surface temperature) in order to attain more realistic results. These kinds of models need to have a function that describes the real low-density riming process. Analysing previous results, it is clear that several different empirical parametrizations are employed to describe density. These parametrizations relate density to growth parameters through the variable X = Vob/Ts, where Vo is the impact velocity of droplets into the target, b is the droplet size, and Ts the hail surface temperature. These empirical expressions give different density values for identical growth conditions. It is important to note that these parametrizations stem from experimental data obtained in very different growth conditions and with different collector geometries. Working with experimental density data, we can show that different parametrizations are equivalent if X is defined in an appropriate way (taking into account impact velocity and collector geometry). Different environmental conditions are taken into account by means of Stokes' parameter. Due to this finding, we have aimed at developing a parametrization to be used in cloud models, which satisfactorily represents all experimental results."
"6506126271;7005485117;","Low-frequency controls on the thresholds of sea surface temperature over the western tropical Pacific",2002,"10.1175/1520-0442(2002)015<1626:LFCOTT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036649090&doi=10.1175%2f1520-0442%282002%29015%3c1626%3aLFCOTT%3e2.0.CO%3b2&partnerID=40&md5=0f3ffefa858fab2302cd0169901c953d","In this study, the Florida State University Coupled Global Spectral Model (FSUCGSM) is utilized to examine the possible regulation of the warm pool SST and its contributors. The model is run for 1 yr to obtain the residue-free time evolution of the warm pool SST. The results are verified against NCEP SST analysis for the period of the model integration. The best agreement was seen over the western equatorial Pacific. The initial analysis of the model output has suggested that the warm pool SST is derived mainly by three important types of oscillations, namely, semiannual. 10-25-, and 30-60-day oscillations. Further examination using Butterworth bandpass filter and EOF analysis has revealed that the tendency of solar radiation is the primary cause of the high-frequency oscillations (20-25 and 30-60 day) and secondary cause for the low-frequency oscillations. Moreover, the evaporative cooling is found to be the primary cause of the low-frequency oscillations and secondary cause for the high-frequency oscillations. The variations of these two forcings were found to be strongly related to convective activities. At high frequencies, convective activities are associated with equatorial waves, whereas at low frequencies such conditions are derived by the migration of the ITCZ. In relation to the atmospheric moisture content, it was found that the cloud shortwave forcing plays the most crucial role in the solar radiation. The connection between convective activities and the changes in the evaporative cooling is found to be through the humidity deficit at low-frequency oscillations and surface wind speed at high-frequency oscillations. A careful examination of the SST-convection interaction has revealed that the warm pool SST may have an upper limit as suggested by earlier authors."
"7004159070;7404577357;35481796400;7403442230;6603451873;6506025591;","Three-satellite comparison of polar mesospheric clouds: Evidence for long-term change",2002,"10.1029/2001jd000668","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1942435292&doi=10.1029%2f2001jd000668&partnerID=40&md5=f449466b80caec6be0e396b77c0e00cb","Measurements of polar mesospheric clouds (PMCs) from three different satellite instruments are compared. These instruments are the Solar Mesospheric Explorer (SME), the Wind Imaging Interferometer (WINDII), and the Polar Ozone and Aerosol Measurement (POAM II). These measurements have been put on a common basis, correcting for differences in the wavelengths and measurement techniques used. This common basis is the probability distribution of the excess extinction ratio (EER) at a standard wavelength of 265 nm, where the EER is the ratio of the PMC extinction coefficient to the background molecular Rayleigh scattering coefficient. The results indicate that the POAM and WINDII measurements in the Southern Hemisphere had a higher probability of observing bright PMCs during the 1993-1996 time period than SME did a decade earlier in 1983-1986. Local time variations identified in WINDII data are interpreted in terms of a diurnal and semidiurnal component of average EER. These results are qualitatively similar to those found from lidar soundings of noctilucent cloud at sites in Norway and at the South Pole. Differences in interannual variability, local time of the measurements, assumed particle size distributions, and solar cycle effects are ruled out as possible explanations of the differences. Copyright 2002 by the American Geophysical Union."
"7003740015;57213997900;55667068400;24311471900;","Chemical composition and sources of the high Arctic aerosol relevant for cloud formation",2002,"10.1029/2001jd001463","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1942499502&doi=10.1029%2f2001jd001463&partnerID=40&md5=b9c3bce4cbfcdd282b912db3ab45e9a6","The chemical composition, sources, and methods of production of cloud condensation nuclei (CCN) were studied over the pack ice covered Arctic Ocean in summer. After ∼2 days' travel of air over the pack ice, two local CCN sources were identified: particles derived from the bursting bubbles on open water between ice floes (film and jet drops) and particles reaching CCN size by acquisition of oxidation products of dimethyl sulfide. The bubble-derived particle modes were found to have an exponential dependence on prevailing wind speed. The film drop generation depended less on wind speed and jet drop production depended more on wind speed than particles over open water did. However, the enhanced presence of film drop particles at wind speeds &lt;5 m s-1 suggested a source of bubbles, other than wind, that is most active during clear sky days and ice melting. The film drop particles were mainly organic in nature, but their sea-salt component increased at high wind speeds &gt;12 m s-1to dominate both mass and number. The jet drop mode was composed largely of sea salt, making a significant mass contribution already for wind speeds &gt;5 m s-1. However, the smaller-sized jet drops were not pure sodium chloride but contained a varied and appreciable organic component. The sulfur-containing particles dominated the CCN population and mass for the most common wind speeds of 5-12 m s-1. Measured CCN concentrations were on average less than would have been expected from either a sulfate or a sea-salt composition and the observed particle-size distribution. It is concluded that other components, probably organic, depressed the nucleating ability of the particles. However, on clear sky days, there were a majority of occasions on which CCN concentrations were more than predicted from a sulfate composition and the measured size distribution. Copyright 2002 by the American Geophysical Union."
"37032346000;35237545900;7202155374;","Radiative effects of aerosols on the evolution of the atmospheric boundary layer",2002,"10.1029/2001jd000754","https://www.scopus.com/inward/record.uri?eid=2-s2.0-18144439596&doi=10.1029%2f2001jd000754&partnerID=40&md5=dba95c6042bad4fd511422f6657a6a96","This study investigates the impacts of tropospheric aerosols on the evolution of the atmospheric boundary layer (ABL) for dry subsiding regions by conducting simulations with a high-resolution ABL model. The scattering and absorption of aerosols diminish the surface radiation, inhibiting the sensible heat flux and evaporation and inducing feedbacks such as the enhanced stratification and change in relative humidity in the surface layer. The reduced sensible heat due to aerosol backscattering lowers the air temperature and suppresses the growth of the ABL. The resultant reduction of entrainment heating contributes to an additional cooling. The decreased entrainment drying competes with the reduced surface evaporation, so that the net effect can be either an increase or a decrease of the ABL moisture, depending on the soil moisture. Aerosol absorption decreases the turbulent heating but simultaneously increases the solar heating, increasing the air temperature and decreasing the strength of capping inversion. The resultant rise of the top of the ABL compensates the lowering due to the reduced buoyancy flux. With strong aerosol absorption, the increased entrainment heating enhances the ABL warming. Both the increased entrainment drying and the reduced evaporation decrease the ABL moisture. The increased warmth and dryness of the ABL imply that absorbing aerosols within the ABL decrease the probability of formation of boundary layer clouds, causing additional warming through cloud-feedbacks. The results are sensitive to the vertical distribution of absorbing aerosols. Absorbing aerosol above the ABL increases the strength of capping inversion and reduces the top of the ABL, hence decreasing the entrainment drying and moistening the ABL. Copyright 2002 by the American Geophysical Union."
"6603620985;7003440089;6603076673;","Marine air intrusion into the Adelie Land sector of East Antarctica: A study using the regional climate model (MAR)",2002,"10.1029/2000jd000274","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17044455241&doi=10.1029%2f2000jd000274&partnerID=40&md5=0fe0ed8204945f6e772cb7c25862062b","Marine air intrusion and subsequent cloud formation plays a dominant role in the energy budget and mass balance of the Antarctic. However, the intrusion is very difficult to understand using the ground-based measurements alone. In this paper we present simulations of marine air intrusion into the Adelie Land, East Antarctica, using the Modèle Atmosphérique Régional (MAR), for July 1994 and January 1995. The model is nested into the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses. The simulations show a strong influence of large-scale disturbances, over the ocean, which helped in the penetration of marine air into the interior and the formation of clouds. Each marine air intrusion episode resulted in cloud formation in July 1994. Blocking anticyclones have also been found to be responsible for much of the moisture transport far into the interior elevated locations. MAR simulations, as well as ECMWF analyses, show influence of cyclones in strengthening and prolonging the surface layer flow. The study also indicated that the influence of depressions on surface winds is pronounced during the period when the depression is approaching the Adelie Land coast. Copyright 2002 by the American Geophysical Union."
"56264677300;35459245100;35461255500;","Condensation/evaporation of insoluble organic vapor as functions of source rate and saturation vapor pressure",2002,"10.1029/2001jd001228","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17044461776&doi=10.1029%2f2001jd001228&partnerID=40&md5=0ec06667962a57d963b27c0b26174b1d","Condensation growth of atmospheric particles by insoluble organic vapors was studied by a monodisperse aerosol dynamics model MONO32 including atmospheric chemistry mechanism. The source rate of the vapor and its saturation vapor density at a particle surface were varied. The initial particle number size distribution was assumed to be bimodal, and aerosol was initially an internal mixture of particles consisting of soluble sulphuric acid and insoluble organic material in a ratio of 1:1. Model simulations predicted that if the ratio of the vapor source rate and the condensation sink of particles, Q/CS, exceeded 108 cm-3 and the vapor was nonvolatile or low volatile, the 10 nm nuclei grew with the growth rates of 2.5-3 nm h-1 and could act as cloud condensation nuclei in supersaturations of 1.6% or lower after 24 h simulation. Then the vapors must have saturation vapor pressures less than 7 × 106 cm-3. However, the higher the ratio of Q/CS, the higher the saturation vapor pressure could be. When the vapor was highly volatile, i.e., the saturation vapor density was high enough, in our simulations greater than 6 × 107 cm-3 the Ostwald ripening was observed. Then the nucleation mode particles were not able to grow but coagulated with larger particles without causing any significant impact on climate. An analytical expression for the saturation vapor density for the Ostwald ripening (cOst) was derived as a function of the ratio of Q/CS. Sensitivity tests for the accommodation coefficient and thermodynamic parameters as well as their effects on cOst were investigated. Copyright 2002 by the American Geophysical Union."
"7003591311;7004885872;","Analysis of the influence of film-forming compounds on droplet growth: Implications for cloud microphysical processes and climate",2002,"10.1175/1520-0469(2002)059<2006:AOTIOF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037096558&doi=10.1175%2f1520-0469%282002%29059%3c2006%3aAOTIOF%3e2.0.CO%3b2&partnerID=40&md5=670134b094441612f86ae698be814813","Decades of cloud microphysical research have not provided conclusive understanding of the physical processes responsible for droplet spectral broadening. Numerous mechanisms have been proposed-for example, entrainment mixing, vortex shedding, giant cloud condensation nuclei (CCN), chemical processing of CCN, and radiative cooling-all of which are likely candidates under select conditions. In this paper it is suggested that variability in the composition of CCN, and in particular, the existence of condensation inhibiting compounds, is another possible candidate. The inferred potential abundance of these amphiphilic film-forming compounds (FFCs) suggests that their effect may be important. Using a cloud parcel model with a simplified treatment of the effect of FFCs, it is shown that modest concentrations of FFCs (on the order of 5% of the total aerosol mass) can have a marked effect on drop growth and can cause significant increases in spectral dispersions. Moreover, it is shown that FFCs may, in some cases, reduce the number concentration of cloud droplets, with implications for cloud-climate feedbacks. This trend is at least in qualitative agreement with results from a recent field campaign."
"7003406400;","A prognostic parameterization for the subgrid-scale variability of water vapor and clouds in large-scale models and its use to diagnose cloud cover",2002,"10.1175/1520-0469(2002)059<1917:APPFTS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037096559&doi=10.1175%2f1520-0469%282002%29059%3c1917%3aAPPFTS%3e2.0.CO%3b2&partnerID=40&md5=54f171184d5b74692736a6c756042345","A parameterization for the horizontal subgrid-scale variability of water vapor and cloud condensate is introduced, which is used to diagnose cloud fraction in the spirit of statistically based cloud cover parameterizations. High-resolution cloud-resolving model data from tropical deep convective scenarios were used to justify the choice of probability density function (PDF). The PDF selected has the advantage of being bounded above and below, avoiding the complications of negative or infinite water mixing ratios, and can give both negatively and positively skewed functions as well as symmetric Gaussian-like bell-shaped curves, without discrete transitions, and is mathematically straightforward to implement. A development from previous statistical parameterizations is that the new scheme is prognostic, with processes such as deep convection, turbulence, and microphysics directly affecting the distribution of higher-order moments of variance and skewness. The scheme is able to represent the growth and decay of cirrus cloud decks and also the creation of cloud in clear sky or breakup of an overcast cloud deck by boundary layer turbulence. After introducing the mathematical framework, results using the parameterization in a climate model are shown to illustrate its behavior. The parameterization is shown to reduce cloud cover biases almost globally, with a marked improvement in the stratocumulus regions in the eastern Pacific and Atlantic Oceans."
"7404416268;6603639908;7203062127;8571512400;7006752044;","Comparison of Arctic climate simulations by uncoupled and coupled global models",2002,"10.1175/1520-0442(2002)015<1429:COACSB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037096651&doi=10.1175%2f1520-0442%282002%29015%3c1429%3aCOACSB%3e2.0.CO%3b2&partnerID=40&md5=083e94482e0821aa0797fdabdb30d83e","Simulations of present-day Arctic climate are assessed from suites of 1) 13 global atmosphere-only models from the Atmospheric Model Intercomparison Project (AMIP-II) and 2) 8 coupled atmosphere-ocean-ice models from the Data Distribution Center of the Intergovernmental Panel on Climate Change (IPCC). The assessment highlights the impact of coupling on the simulated Arctic climate, and also the improvement of the uncoupled models relative to a previous (early 1990s) phase of the AMIP project. The across-model variance of the simulated air temperature is larger in the coupled models than in the uncoupled models, and the spatial pattern of the variance indicates that differences in the coupled models' simulated sea ice contribute to the larger variance of temperature. The coupled models are also several degrees colder than the uncoupled models during the winter half of the year. As was the case with the earlier AMIP models, the simulated precipitation still exceeds the observational estimates, particularly over the terrestrial watersheds of the Arctic Ocean. The bias is larger in the coupled models and is strongest during the cold season. Both the coupled and the uncoupled models suffer from a bias of Arctic sea level pressure that will adversely impact the simulated sea ice motion and the spatial distribution of ice thickness. The bias appears as a shift of mass from the Beaufort sector of the Arctic Ocean to the Asian coastal seas. Improvements in simulated cloud coverage from AMIP-I to AMIP-II are apparent in a reduction of the across-model scatter of the AMIP-II cloud coverage and also in a more realistic annual cycle of the cloud fraction composited over the AMIP-II models. The Arctic surface radiative fluxes vary widely among the AMIP-II models, especially under cloudy skies."
"7004364155;56493740900;","Top-of-atmosphere direct radiative effect of aerosols over the tropical oceans from the Clouds and the Earth's Radiant Energy System (CERES) satellite instrument",2002,"10.1175/1520-0442(2002)015<1474:TOADRE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037096635&doi=10.1175%2f1520-0442%282002%29015%3c1474%3aTOADRE%3e2.0.CO%3b2&partnerID=40&md5=c0c53a7b55b9974eb2dd9e3150ea3698","Nine months of the Clouds and the Earth's Radiant Energy System (CERES)/Tropical Rainfall Measuring Mission (TRMM) broadband fluxes combined with the TRMM visible infrared scanner (VIRS) high-resolution imager measurements are used to estimate the daily average direct radiative effect of aerosols for clear-sky conditions over the tropical oceans. On average, aerosols have a cooling effect over the Tropics of 4.6 ± 1 W m-2. The magnitude is ≈ 2 W m-2 smaller over the southern tropical oceans than it is over northern tropical oceans. The direct effect derived from CERES is highly correlated with coincident aerosol optical depth (τ) retrievals inferred from 0.63-μm VIRS radiances (correlations coefficient of 0.96). The slope of the regression line is ≈ - 32 W m-2 τ-1 over the equatorial Pacific Ocean, but changes both regionally and seasonally, depending on the aerosol characteristics. Near sources of biomass burning and desert dust, the aerosol direct effect reaches - 25 to ∼ 30 W m-2. The direct effect from CERES also shows a dependence on wind speed. The reason for this dependence is unclear-it may be due to increased aerosol (e.g., sea-salt or aerosol transport) or increased surface reflection (e.g., due to whitecaps). The uncertainty in the tropical average direct effect from CERES is ≈ 1 W m-2 (≈ 20%) due mainly to cloud contamination, the radiance-to-flux conversion, and instrument calibration. By comparison, uncertainties in the direct effect from the Earth Radiation Budget Experiment (ERBE) and CERES ""ERBE-like"" products are a factor of 3-5 times larger."
"6603021857;7005173878;55605771904;","On the feedback of stratospheric clouds on polar climate",2002,"10.1029/2002GL014659","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036624046&doi=10.1029%2f2002GL014659&partnerID=40&md5=ea593a6f7cdec01542c3897d1672395f","Past climates, such as the Eocene (55 - 38 Ma), experienced dramatically warmer polar winters. Global climate models run with Eocene-like boundary conditions have under-predicted polar temperatures, a discrepancy which has stimulated a recent hypothesis that polar stratospheric clouds may have been important. We propose that such clouds form in response to higher CO2 via changes in stratospheric circulation and water content. We show that the absence of this mechanism from models of Eocene climate may be attributable to poor vertical resolution in the neighborhood of the tropical tropopause. This may cause the models to underestimate future greenhouse warming."
"7003899619;6603940684;7003935733;26643440200;6602078681;","The Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Atmosphere (PATMOS) climate dataset: Initial analyses and evaluations",2002,"10.1175/1520-0442(2002)015<1243:TAVHRR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036609509&doi=10.1175%2f1520-0442%282002%29015%3c1243%3aTAVHRR%3e2.0.CO%3b2&partnerID=40&md5=ae455165c0a1716ba60270c39279372b","As part of the joint National Oceanic and Atmospheric Administration-National Aeronautics and Space Administration (NOAA-NASA) Pathfinder program, the NOAA/National Environmental Satellite, Data and Information Service (NESDIS) has created a research-quality atmospheric, climate-scale dataset through the reprocessing of archived Advanced Very High Resolution Radiometer (AVHRR) observations from four afternoon satellites, in orbit since 1981. The raw observations were recalibrated using a vicarious calibration technique for the AVHRR reflectance channels and an improved treatment of the nonlinearity of the three infrared emittance channels. State-of-the-art algorithms are used in the Pathfinder Atmosphere (PATMOS) project to process global AVHRR datasets into statistics of channel radiances, total cloud amount, components of the earth's radiation budget, and aerosol optical thickness over oceans. The radiances and earth radiation budget components are determined for clear-sky and all-sky conditions. The output products are generated on a quasi-equal-area grid with a spatial resolution of approximately 110 km, with twice-a-day temporal resolution, and averaged over 5-day (pentad) and monthly time periods. The quality of the products is assessed relative to independent surface or satellite observations of these parameters. This analysis shows that the PATMOS data are sufficiently accurate for studies of the interaction of clouds and aerosol with solar and terrestrial radiation, and of climatic phenomena with large signals, for example, the annual cycle, monsoons, and the four ENSOs and two major volcanic eruptions that occured during the 19-yr PATMOS period. Analysis also indicates that smaller climate signals, such as those associated with longer-term trends in surface temperature, may be difficult to detect due to the presence of artifacts in the time series that result from the drift of each satellite's observation time over its mission. However, a simple statistical method is employed to remove much of the effect caused by orbital drift. The uncorrected PATMOS dataset is accessible electronically."
"57203809453;7006635125;","Maximum urban heat island intensity in Seoul",2002,"10.1175/1520-0450(2002)041<0651:MUHIII>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036602638&doi=10.1175%2f1520-0450%282002%29041%3c0651%3aMUHIII%3e2.0.CO%3b2&partnerID=40&md5=f1c1545ecf3eda57595f538fb7b0f759","The maximum urban heat island (UHI) intensity in Seoul, Korea, is investigated using data measured at two meteorological observatories (an urban site and a rural site) during the period of 1973-96. The average maximum UHI is weakest in summer and is strong in autumn and winter. Similar to previous studies for other cities, the maximum UHI intensity is more frequently observed in the nightime than in the daytime, decreases with increasing wind speed, and is pronounced for clear skies. A multiple linear regression analysis is performed to relate the maximum UHI to meteorological elements. Four predictors considered in this study are the maximum UHI intensity for the previous day, wind speed, cloudiness, and relative humidity. The previous-day maximum UHI intensity is positively correlated with the maximum UHI, and the wind speed, cloudiness, and relative humidity are negatively correlated with the maximum UHI intensity. Among the four predictors, the previous-day maximum UHI intensity is the most important. The relative importance among the predictors varies depending on time of day and season. A three-layer back-propagation neural network model with the four predictors as input units is constructed to predict the maximum UHI intensity in Seoul, and its performance is compared with that of a multiple linear regression model. For all test datasets, the neural network model improves upon the regression model in predicting the maximum UHI intensity. The improvement of the neural network model upon the regression model is 6.3% for the unstratified test data, is higher in the daytime (6.1%) than in the nightime (3.3%), and ranges from 0.8% in spring to 6.5% in winter."
"7101879730;6701775319;7102297580;7003394933;6506779776;7005116314;6701703163;","Carbon sequestration in a high-elevation, subalpine forest",2002,"10.1046/j.1365-2486.2002.00480.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036098289&doi=10.1046%2fj.1365-2486.2002.00480.x&partnerID=40&md5=9603550243d3be7596d11f3eec88b196","We studied net ecosystem CO2 exchange (NEE) dynamics in a high-elevation, subalpine forest in Colorado, USA, over a two-year period. Annual carbon sequestration for the forest was 6.71 mol C m-2 (80.5 g C m-2) for the year between November 1, 1998 and October 31, 1999, and 4.80 mol C m-2 (57.6 g C m-2) for the year between November 1, 1999 and October 31, 2000. Despite its evergreen nature, the forest did not exhibit net CO2 uptake during the winter, even during periods of favourable weather. The largest fraction of annual carbon sequestration occurred in the early growing-season; during the first 30 days of both years. Reductions in the rate of carbon sequestration after the first 30 days were due to higher ecosystem respiration rates when mid-summer moisture was adequate (as in the first year of the study) or lower mid-day photosynthesis rates when mid-summer moisture was not adequate (as in the second year of the study). The lower annual rate of carbon sequestration during the second year of the study was due to lower rates of CO2 uptake during both the first 30 days of the growing season and the mid-summer months. The reduction in CO2 uptake during the first 30 days of the second year was due to an earlier-than-normal spring warm-up, which caused snow melt during a period when air temperatures were lower and atmospheric vapour pressure deficits were higher, compared to the first 30 days of the first year. The reduction in CO2 uptake during the mid-summer of the second year was due to an extended drought, which was accompanied by reduced latent heat exchange and increased sensible heat exchange. Day-to-day variation in the daily integrated NEE during the summers of both years was high, and was correlated with frequent convective storm clouds and concomitant variation in the photosynthetic photon flux density (PPFD). Carbon sequestration rates were highest when some cloud cover was present, which tended to diffuse the photosynthetic photon flux, compared to periods with completely clear weather. The results of this study are in contrast to those of other studies that have reported increased annual NEE during years with earlier-than-normal spring warming. In the current study, the lower annual NEE during 2000, the year with the earlier spring warm-up, was due to (1) coupling of the highest seasonal rates of carbon sequestration to the spring climate, rather than the summer climate as in other forest ecosystems that have been studied, and (2) delivery of snow melt water to the soil when the spring climate was cooler and the atmosphere drier than in years with a later spring warm-up. Furthermore, the strong influence of mid-summer precipitation on CO2 uptake rates make it clear that water supplied by the spring snow melt is a seasonally limited resource, and summer rains are critical for sustaining high rates of annual carbon sequestration."
"57203053317;26643250500;","First interactive simulations of cirrus clouds formed by homogeneous freezing in the ECHAM general circulation model",2002,"10.1029/2001jd000767","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547357146&doi=10.1029%2f2001jd000767&partnerID=40&md5=ac17e1c19285336fad1d3c77ae617819","A physically based parameterization for the nucleation and initial growth of ice crystals in cirrus clouds at low (<238 K) temperatures prevailing in the upper troposphere and in the tropopause region is implemented in the ECHAM general circulation model (GCM). With this model we performed the first interactive simulations of cirrus clouds in a global climate model. As homogeneous ice crystal nucleation requires relative humidities with respect to ice of 140-170% at these temperatures, we abandoned the saturation adjustment scheme previously used to compute the properties of cirrus clouds in GCMs. The comparison with relative humidity data taken on commercial aircraft showed that ECHAM reproduces the frequency distribution of supersaturation with respect to ice in cloud-free regions well especially if high values of the subgrid-scale vertical velocity are assumed. On the other hand, the higher frequency of occurrence of high supersaturations in the model may point to heterogeneous freezing as the missing mechanism for ice formation. We found that homogeneous freezing may be limited by the number of hygroscopic aerosols present. However, as the ice water content remains the same for the natural and present-day aerosol scenarios the longwave radiation does not change. Thus anthropogenic aerosol and precursor emissions have only a small effect on cirrus formed by homogeneous freezing. Aircraft emissions of sulfate aerosols are not likely to be important for cirrus formation. Aircraft soot emissions may be important if the soot particles nucleate ice more efficiently than by homogeneous freezing."
"7006344866;24080667300;7003777379;7006461606;55168841800;35395776600;7006592026;","Correlation between model-calculated anthropogenic aerosols and satellite-derived cloud optical depths: Indication of indirect effect?",2002,"10.1029/2000jd000208","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547606888&doi=10.1029%2f2000jd000208&partnerID=40&md5=915ea21b56612c01417e8273d4d52c8a","We consider two independently derived data sets. The first represents the annually averaged distribution of anthropogenic aerosols over East Asia as derived by a coupled regional climate/chemical transport model. The other is the annually averaged distributions of cloud optical depths and cloud amount over East Asia derived by the International Satellite Cloud Climatology Project (ISCCP) for 1990, 1991, 1992, and 1993. We find a remarkable similarity in the distributions of model-calculated anthropogenic aerosols and ISCCP-reported cloud optical depths, with both exhibiting a region of enhanced values extending over the east central portion of China, between the Sichuan Basin and the Yangtze Delta, and then in an easterly direction over the East China Sea, Japan, and South Korea, and the western edge of the Pacific Ocean. Linear regression between the estimated aerosol column burdens and the cloud optical depths yields an r2 &gt; 0.6, indicating that the correlations are statistically significant at a confidence level that is &gt;99.9% and that more than 60% of the variation in the cloud optical depths is related to variations in the anthropogenic aerosol abundances. Multivariate analysis involving the distributions of boundary layer relative humidity and precipitation over East Asia, as well as that of the model-calculated anthropogenic aerosols and the ISCCP-reported cloud properties, indicates that the relationship between anthropogenic aerosols and cloud optical depth is unique to these two variables and not symptomatic of a more general mechanism involving the hydrologic cycle. Trend analysis of the ISCCP data suggests that there was an upward trend in cloud optical depths over areas in East Asia impacted by air pollution during the early 1990s that would have corresponded to the likely increase in anthropogenic aerosol concentrations over this period in East Asia in response to growing anthropogenic emissions. A likely explanation for these findings is that there is a mechanistic coupling between anthropogenic aerosol concentrations and cloud optical properties; one such mechanism is the so-called first and second indirect effect by which aerosols enhance the optical depths and albedos of clouds by increasing the number of droplets within clouds and suppressing precipitation from clouds, respectively. The regressions further suggest that the cloud optical depths increase on average by 0.16 for each 1 mg m-2 increase in the column-integrated anthropogenic aerosol burden. Simple box-model calculations suggest that this is equivalent to a cooling over the model domain from anthropogenic aerosols via the indirect effect that is a factor of about 1.5 times that from the direct effect. Accounting for a possible underestimate in model-simulated aerosol concentrations over the model domain of as much as a factor of 0.6 would lower the estimated cooling from the indirect effect to about 1 times that from the direct effect. In contrast to the results using ISSCP-derived cloud optical depths, the correlation between the model-calculated anthropogenic aerosols and average cloud amount over the model domain was relatively weak and inconsistent. This result arose perhaps because of a cancelling of the competing influences on cloud lifetime and frequency by the second indirect effect and the so-called semi direct effect (i.e., the suppression of clouds by absorbing aerosols)."
"7006184606;","A simple model of multiple climate regimes",2002,"10.1029/2001jd001002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345782225&doi=10.1029%2f2001jd001002&partnerID=40&md5=dd3ca89201c4f3655f92ff76f1b96f93","Among the most intriguing enigmas of the climate system is that on the one hand, the Earth's climate appears to be exquisitely sensitive to relatively minor variations in the distribution of insolation owing to orbital variations, but on the other hand, it is in a grosser sense stable, in that it has varied only moderately in response to a roughly 30% increase in solar insolation over the life of the planet. To this enigma may be added the evidence that climate may undergo extraordinarily abrupt transitions. An attractive idea to help explain these characteristics is the notion that the Earth possesses a limited number of stable climate regimes that may overlap to produce multiple equilibrium states for the same solar forcing. Here we present a simple model that produces such overlapping stable equilibria, based on a few key feedback processes. These include control of atmospheric clouds and water vapor by the large-scale circulation of the atmosphere, control of the depth and intensity of the ocean's thermohaline circulation by tropical cyclones, and the dependence of atmospheric CO2 content on ocean temperature and the strength of the thermohaline circulation. We will show that these key feedback processes produce a climate with two or three stable, overlapping climate regimes. Subjecting this system to variations in climate forcing can account for several observed features of the climate system, including abrupt transitions, sensitivity to orbital variations, arctic warmth and high bottom water temperature during the Eocene and late Cretaceous, tempestites, and possible episodes of deep ocean anoxia during the Cretaceous."
"7005171879;","Indirect climate forcing over the western US from Asian dust storms",2002,"10.1029/2001gl014051","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037095873&doi=10.1029%2f2001gl014051&partnerID=40&md5=0d7242a4067aa13be4d35788f48f7ce4","Aerosols lofted to high altitudes by springtime Asian dust storms advect across the Pacific Ocean and, as recognized in recent years, regularly reach the western US. As part of our long-term cirrus cloud research program using remote sensing measurements, we have observed unusually warm cirrus ice clouds associated with transported Asian dust aerosols. The polarization lidar data presented for illustration here suggest that the dust particles, which are indicated to be especially active ice nuclei, can affect the formation and phase of clouds, and hence alter their radiative properties at least as far away as the eastern Great Basin of the US."
"6603600592;7004159640;9040973700;7003653992;7004090239;6603026917;","Seasonal niche strategy of the bloom-forming dinoflagellate Heterocapsa triquetra",2002,"10.3354/meps232045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037012998&doi=10.3354%2fmeps232045&partnerID=40&md5=f01e6cc5ad273d69e98eeb005d0abb07","Heterocapsa triquetra is one of the most common bloom-forming dinoflagellates found in estuaries and near shore regions around the world. This work examined the environmental factors associated with 3 separate wintertime H. triquetra blooms in the shallow tidally mixed Newport River estuary, North Carolina, USA. During 2 of the blooms in 1982 and 1983, the estuary was sampled from a fixed, single location every hour for 14 d. During the third study, the estuary was sampled at 9 fixed locations over its entire length each week from late December 1997 through March 1998. This time period included the formation and decline of the H. triquetra bloom. Barometric pressure, precipitation, photosynthetically active radiation salinity, temperature, nutrient concentrations, and chl a were measured in each study. During the 1997-1998 study, pigments were analyzed using HPLC to characterize the phytoplankton assemblages and the dominant dinoflagellates in each sample were counted. The prevailing environmental conditions associated with the wintertime blooms were largely the result of atmospheric forcing. Low pressure systems moved through the study area at 3 to 4 d intervals and were accompanied by low ambient air temperatures and regular rainfall. Runoff following the rainfall events supplied inorganic nutrients critical for bloom initiation and development. It also created a mesohaline frontal zone in the middle portion of the estuary with salinity and hydrodynamic conditions favorable for H. triquetra growth. Here, the H. triquetra bloom reached its maximal development with chl a levels &gt;100 μg l-1 and cell densities between 1 and 6 × 106l-1. As the H. triquetra bloom developed, nutrient inputs from the river became insufficient to meet growth demand and H. triquetra began feeding mixotrophically, supplementing its nutritional requirements and reducing competition from co-occurring dinoflagellates. Cloud cover associated with the low pressure systems transiently limited H. triquetra growth as did low temperatures. More importantly though, low temperatures limited micro- and macrozooplankton populations to such an extent that grazing losses were minimal. Hence, in order to bloom, H. triquetra optimizes a suite of factors including low grazing pressure, increased nutrient inputs, alternative nutrient sources, and favorable salinity and hydrodynamic conditions, as well as the negative factors of temperature-limited growth, short day lengths, and periods of transient light limitation."
"7403159332;7202367208;","Daily maximum and minimum temperature trends in a climate model",2002,"10.1029/2001gl014556","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036558536&doi=10.1029%2f2001gl014556&partnerID=40&md5=f6c709aad0ad480bdeb014d34750669c","The recent observed global warming trend over land has been characterised by a faster warming at night, leading to a considerable decrease in the diurnal temperature range (DTR). Analysis of simulations of a climate model including observed increases in greenhouse gases and sulphate aerosols reveals a similar trend in the DTR of -0.2°C per century, albeit of smaller magnitude than the observed -0.8°C per century. This trend in the model simulations is related to changes in cloud cover and soil moisture. These results indicate that the observed decrease in the DTR could be a signal of anthropogenic forcing of recent climate change."
"7404325680;35555822400;7201853507;7401718184;7102016719;","Long-term climate patterns in Alaskan surface temperature and precipitation and their biological consequences",2002,"10.1109/TGRS.2002.1010902","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036563780&doi=10.1109%2fTGRS.2002.1010902&partnerID=40&md5=372b9417456745b3fc493572d57eaf09","Mean monthly climate maps of Alaskan surface temperature and precipitation produced by the parameter-elevation regression on independent slopes model (PRISM) were analyzed. Alaska is divided into interior and coastal zones with consistent but different climatic variability separated by a transition region; it has maximum interannual variability but low long-term mean variability. Pacific decadal oscillation (PDO)- and El Niño southern oscillation (ENSO)-type events influence Alaska surface temperatures weakly (1-2 °C) statewide. PDO has a stronger influence than ENSO on precipitation but its influence is largely localized to coastal central Alaska. The strongest influence of Arctic oscillation (AO) occurs in northern and interior Alaskan precipitation. Four major ecosystems are defined. A major eco-transition zone occurs between the interior boreal forest and the coastal rainforest. Variability in insolation, surface temperature, precipitation, continentality, and seasonal changes in storm track direction explain the mapped ecosystems. Lack of westward expansion of the interior boreal forest into the western shrub tundra is influenced by the coastal marine boundary layer (enhanced cloud cover, reduced insolation, cooler surface and soil temperatures). In this context, the marine boundary layer acts in an analogous fashion to the orographic features which form the natural boundaries of other Alaskan ecosystems. Variability in precipitation may play a secondary role."
"6603710858;57206288401;","On the variability and modelling of surface albedo and long-wave radiation components",2002,"10.1016/S0168-1923(02)00013-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037197997&doi=10.1016%2fS0168-1923%2802%2900013-8&partnerID=40&md5=06e2635b15e72796f921e4b3b0eb3b66","Variability and modelling of surface albedo and long-wave radiation components are presented for grassland sites whose elevation ranged from 212 to 1489 m a.s.1. Data sets utilised for the study were recorded in south-west Germany during REKLIP (REgio KLIma Projekt), which extended from 1991 to 1996. Inter-annual variability of albedo a and outgoing long-wave radiation R1 ↑ at the study sites was less than 9%, thus, rendering the measured data quite suitable for diagnostic and modelling purposes. Annually, α extended from 22 (at 212 m a.s.1.) to 36% (at 1489 m a.s.1.), while R1 ↑ declined from 367 (at 212 m a.s.1.) to 326 Wm-2 (at 1489 m a.s.1.). Consequently, radiation efficiency at the lowest elevated grassland site was approximately 1.3 times that of the highest elevated site. The observed decline in incoming long-wave radiation R1 ↓ with altitude relates physically to the vertical distribution of air temperature and green house gases (particularly atmospheric water vapour and CO2). Ratio of annual R1 ↓ to R1 ↑ at the sites was about 0.87. While albedo dropped with cloud cover N at both low and high altitude sites in summer, there was, however, a noteworthy discrepancy in winter, when α declined with N at the low altitude location but increased with it at the high altitude location. Mean daily sums of R1 ↑ fell with N in summer, but rose with it in winter for both low and high altitude sites. In view of the major role played by altitude in regulating climate and radiative budget at the surface, we have extended Dong et al. model to include seasonal altitude terms for estimating grassland albedo. In addition, outgoing long-wave radiation under all sky conditions has been expressed here as a function of air temperature, absorbed short-wave radiation and altitude. © 2002 Elsevier Science B.V. All rights reserved."
"6603946891;57203183278;7101944535;7003459207;","Visual and lidar observations of noctilucent clouds above Logan, Utah, at 41.7°N",2002,"10.1029/2001jd001180","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037181937&doi=10.1029%2f2001jd001180&partnerID=40&md5=6cfac264fff8806fd172cec8ad0318e9","Noctilucent clouds (NLCs) were observed from a midlatitude site (Logan, Utah) on the evenings of 22 and 23 June 1999 mountain daylight time. On both nights the clouds were seen for approximately an hour by experienced observers, and they were photographed. The NLC was also observed on the second evening for approximately an hour in the zenith with the Rayleigh-scatter lidar at the Atmospheric Lidar Observatory, which is operated by the Center for Atmospheric and Space Sciences on the campus of Utah State University. These observations enabled several of the properties of the cloud to be determined. They were within the range of those observed at higher latitudes, but notably the NLC was very weak and thin. These combined visual and lidar observations unequivocally support the identification of the cloud as a noctilucent cloud. The midlatitude location (41.74°N, 111.81°W) is ∼10° equatorward of previous observations. This equatorward penetration is significant because of potential implications about global change or the global circulation."
"57212781009;","Geographical contributions to global climate sensitivity in a General Circulation Model",2002,"10.1016/S0921-8181(01)00142-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037091307&doi=10.1016%2fS0921-8181%2801%2900142-4&partnerID=40&md5=17375e88819dfd2ca9a1ecb2bb2f380d","This paper addresses two questions: how do radiative contributions to global climate model feedbacks vary geographically, and hence which regions and physical processes are most important in determining final climate sensitivity in a General Circulation Model (GCM)? Offline radiation calculations were used to evaluate in detail the strength and spatial distribution of top of atmosphere (TOA) radiative perturbations for the BMRC GCM under a doubling of CO2. The long wave and short wave radiative perturbations were considered separately. The net global effect of these radiative perturbations determines the strength of the global model feedbacks, and hence the climate sensitivity. The geographical distribution of the radiative perturbations on the other hand helps to identify the model processes that are most important for determining the strength of model feedbacks. This study found that globally, the dominant positive feedbacks were for (a) water vapour amount and height, and cloud height for long wave radiation and (b) albedo and cloud amount for short wave radiation. The dominant negative feedback (apart from the surface temperature term itself) occurred for cloud amount changes in the long wave. Geographically, the contributions to the water vapour feedback strength varied markedly by location, with subtropical, and upper tropospheric regions contributing relatively strongly to the net global feedback. The water vapour height component correlated quite strongly with convective changes while the amount term was correlated with fractional precipitable water changes. The contribution of different precipitable water regimes in the tropics to global water vapour feedback was assessed - relatively dry areas contributed disproportionately, but did not dominate the overall feedback because of their small areas. Contributions to cloud amount and height feedbacks in the long wave were found to be uncorrelated in space, indicating their different controlling processes. The long wave amount component correlated strongly with upper cloud, and convective changes. The short wave component of the cloud feedback depended on cloud changes at all levels, producing its strongest contribution to feedbacks in mid latitudes, where the sign of cloud changes agreed at different heights. The effect of cloud cover on non-cloud feedbacks was also investigated. This study found that clouds weaken all feedbacks, except that of lapse rate, with the greatest impact being on the surface albedo and water vapour amount. The radiative perturbation analysis method presented here proves to be a powerful tool for identifying important physical processes that determine final climate model sensitivity. Crown © 2002 Published by Elsevier Science B.V. All rights reserved."
"8953038700;6603894240;7006016266;7005973015;7102959401;","Cloud variability as revealed in outgoing infrared spectra: Comparing model to observation with spectral EOF analysis",2002,"10.1029/2001GL014176","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037092280&doi=10.1029%2f2001GL014176&partnerID=40&md5=b8b5ac187c6aa16c586ef0fc7bb9f2a1","Spectrally resolved outgoing radiance is a potentially powerful tool for testing climate models. To show how it can be used to evaluate the simulation of cloud variability, which is the principal uncertainty in current climate models, we apply spectral empirical orthogonal function (EOF) analysis to satellite radiance spectra and synthetic spectra derived from a general circulation model (GCM). We show that proper averaging over a correct timescale is necessary before applying spectral EOF analysis. This study focuses on the Central Pacific and the western Pacific Warm Pool. For both observation and GCM output, cloud variability is the dominant contributor to the first principal component that accounts for more than 95% of the total variance. However, the amplitude of the first principal component derived from the observations (2 ∼ 3.4 W m-2) is 2 ∼ 6 times greater than that of the GCM simulation. This suggests that cloud variability in the GCM is significantly smaller than that in the real atmosphere. Copyright 2002 by the American Geophysical Union."
"7006033356;7005455874;35425197200;6506448201;7103116704;7006423931;7004423756;16432029600;","Advection from the North Atlantic as the forcing of winter greenhouse effect over Europe",2002,"10.1029/2001GL014187","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037092342&doi=10.1029%2f2001GL014187&partnerID=40&md5=102d477cface725e9a82359bcadf887d","In winter, large interannual fluctuations in the surface temperature are observed over central Europe. Comparing warm February 1990 with cold February 1996, a satellite-retrieved surface (skin) temperature difference of 9.8 K is observed for the region 50-60°N; 5-35°E. Previous studies show that advection from the North Atlantic constitutes the forcing to such fluctuations. The advection is quantified by Index Ina, the average of the ocean-surface wind speed over the eastern North Atlantic when the direction is from the southwest (when the wind is from another direction, it counts as a zero speed to the average). Average Ina for February 1990 was 10.6 m s-1, but for February 1996 Ina was only 2.4 m s-1. A large value of Ina means a strong southwesterly flow which brings warm and moist air into central Europe at low level, producing a steeper tropospheric lapse rate. Strong ascending motions at 700 mb were observed in association with warm and moist advection from the ocean in February 1990, producing clouds and precipitation. Total precipitable water and cloud-cover fraction have larger values in February 1990 than in 1996. The difference in the greenhouse effect between these two scenarios, this reduction in the heat loss to space, can be translated into a virtual radiative heating of 2.6 W m-2 above the February 1990 surface/atmosphere system, which contributes to a warming of the surface on the order of 2.6 K. Accepting this estimate as quantitatively meaningful, we evaluate the direct effect, the rise in the surface temperature in Europe as a result of the maritime-air inflow, as 7.2 K (9.8 K-2.6 K). Thus, fractional reinforcement by the greenhouse effect is 2.6/7.2, or 36%, a substantial positive feedback. Copyright 2002 by the American Geophysical Union."
"55120726100;7801435157;57213836189;7004377034;7006985218;7402381928;57203488889;7004563021;7404430182;7004031990;8888998100;55906095600;7007042259;","Derivation and validation of Canada-wide coarse-resolution leaf area index maps using high-resolution satellite imagery and ground measurements",2002,"10.1016/S0034-4257(01)00300-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036214130&doi=10.1016%2fS0034-4257%2801%2900300-5&partnerID=40&md5=a225411d4e311ca717778b7bbdbfbe49","Leaf area index (LAI) is one of the surface parameters that has importance in climate, weather, and ecological studies, and has been routinely estimated from remote sensing measurements. Canada-wide LAI maps are now being produced using cloud-free Advanced Very High-Resolution Radiometer (AVHRR) imagery every 10 days at 1-km resolution. The archive of these products began in 1993. LAI maps at the same resolution are also being produced with images from the SPOT VEGETATION sensor. To improve the LAI algorithms and validate these products, a group of Canadian scientists acquired LAI measurements during the summer of 1998 in deciduous, conifer, and mixed forests, and in cropland. Common measurement standards using the commercial Tracing Radiation and Architecture of Canopies (TRAC) and LAI-2000 instruments were followed. Eight Landsat Thematic Mapper (TM) scenes at 30-m resolution were used to locate ground sites and to facilitate spatial scaling to 1-km pixels. In this paper, examples of Canada-wide LAI maps are presented after an assessment of their accuracy using ground measurements and the eight Landsat scenes. Methodologies for scaling from high- to coarse-resolution images that consider surface heterogeneity in terms of mixed cover types are evaluated and discussed. Using Landsat LAI images as the standard, it is shown that the accuracy of LAI values of individual AVHRR and VEGETATION pixels was in the range of 50-75%. Random and bias errors were both considerable. Bias was mostly caused by uncertainties in atmospheric correction of the Landsat images, but surface heterogeneity in terms of mixed cover types were also found to cause bias in AVHRR and SPOT VEGETATION LAI calculations. Random errors come from many sources, but pixels with mixed cover types are the main cause of random errors. As radiative signals from different vegetation types were quite different at the same LAI, accurate information about subpixel mixture of the various cover types is identified as the key to improving the accuracy of LAI estimates. © 2002 Elsevier Science Inc. All rights reserved."
"7005304841;","Small-scale patterns of sulfate aerosol climate forcing simulated with a high-resolution regional climate model",2002,"10.1034/j.1600-0889.2002.00282.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036195222&doi=10.1034%2fj.1600-0889.2002.00282.x&partnerID=40&md5=545a00bc21d39777f0c1ceac0ce56d7f","A high-resolution, regional climate model (RCA2) is employed to evaluate direct and indirect radiative forcing patterns due to man-made sulfate aerosols over Europe and to examine the sensitivity of the results to the choice of model resolution. A simulation encompassing the whole year of 1993 is performed. The model includes an explicit parameterization of the atmospheric sulfur cycle where predicted cloud and precipitation parameters are utilized at each time step. The overall pattern of the monthly mean direct climate effect simulated by the regional climate model is similar to that obtained using global climate models. Calculations over 0.4 and 4.0° spatial resolution indicate that, for the climatic conditions simulated by the RCA2. correlations between small-scale variations of relative humidity and aerosol loading do not contribute substantially to the magnitude of the monthly mean optical thickness. For the monthly mean indirect climate effect, the finer grid spacing in the RCA2 results in a pronounced spatial variability, not visible in global climate model simulations. An interesting questions is whether this variability affects the estimated magnitude of the indirect climate effect. Calculations of the effective droplet radius (re) for 0.4° and 4% spatial resolution indicate a minor importance over the RCA2 model domain (the difference in re is less than 7%). The model generally underestimates the sulfate concentration within the boundary layer, whereas the magnitude of the simulated CDNC and re agrees well with aircraft measurements. Despite an underestimate of the absolute magnitude, the regional pattern of the modeled re resembles that observed by satellite. A number of sensitivity simulations demonstrate that the magnitude of the indirect radiative forcing is highly uncertain. In order to reduce the uncertainty, different parameterizations of the indirect effect should be evaluated in more detail versus measurements of, e.g., aerosol concentration and properties, CDNC. and re at various locations."
"7004540083;6506112116;57126848900;","Implications of the observed mesoscale variations of clouds for the earth's radiation budget",2002,"10.1175/1520-0442(2002)015<0557:IOTOMV>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037088110&doi=10.1175%2f1520-0442%282002%29015%3c0557%3aIOTOMV%3e2.0.CO%3b2&partnerID=40&md5=d9626ffdb8f953ac9c1f270dd5c22841","The effect of small spatial-scale cloud variations on radiative transfer in cloudy atmospheres currently receives a lot of research attention, but the available studies are not very clear about which spatial scales are important and report a very large range of estimates of the magnitude of the effects. Also, there have been no systematic investigations of how to measure and represent these cloud variations. The cloud climatology produced by the International Satellite Cloud Climatology Project (ISCCP) is exploited to 1) define and test different methods of representing cloud variation statistics: 2) investigate the range of spatial scales that should be included: 3) characterize cloud variations over a range of time-and space scales covering mesoscale (30-300 km, 3-12 h) into part of the lower part of the synoptic scale (300-3000 km, 1-30 days); 4) obtain a climatology of the optical thickness, emissivity, and cloud-top temperature variability of clouds that can be used in weather and climate GCMs, together with the parameterization proposed by Cairns et al., to account for the effects of small-scale cloud variations on radiative fluxes; and 5) evaluate the effect of observed cloud variations on the earth's radiation budget. These results lead to the formulation of a revised conceptual model of clouds for use in radiative transfer calculations in GCMs. The complete variability climatology can be obtained from the ISCCP Web site at http://isccp.giss.nasa.gov."
"57206128696;6603646841;7003473171;","Potential climate change impacts on flood producing mechanisms in southern British Columbia, Canada using the CGCMA1 simulation results",2002,"10.1016/S0022-1694(01)00580-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036499755&doi=10.1016%2fS0022-1694%2801%2900580-7&partnerID=40&md5=f96721ff63a788acffaa4ea25d69b9f8","The potential impacts of the future climate change on the causes of flood flows were investigated for two mountainous watersheds located in two different climatic regions of British Columbia. The Canadian Centre for Climate Modeling Analysis General Circulation Model (CGCMa1) has been used to estimate changes in the precipitation and temperature. The UBC Watershed Model (Version 4.0) was used to simulate the discharge of the two study watersheds and to identify the causes of peak flows. In the simulations, apart from changes in precipitation and temperature, changes in the spatial distribution of precipitation with elevation, cloud cover, glacier extension, vegetation distribution, vegetation biomass production, and plant physiology were considered. The results showed that the future climate for the two study watersheds would be wetter and warmer than the present climate. The majority of the flood events in the coastal rainfed watershed of Upper Campbell are and would be generated by fall rainfall events and winter rain-on-snow events, whereas in the interior snowcovered Illecillewaet basin the floods are and would be produced by spring rain and snowmelt events and summer events. The analysis indicated that the overall flood magnitude and frequency of occurrence in the Upper Campbell watershed would increase. On the other hand, the number and the magnitude of the flood flows would decrease under the future climatic conditions in the Illecillewaet basin. Based on these findings, different management practices should be applied in the two watersheds to overcome the effects of the future climate change. © 2002 Elsevier Science B.V. All rights reserved."
"57203053317;","A glaciation indirect aerosol effect caused by soot aerosols",2002,"10.1029/2001GL014357","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037085062&doi=10.1029%2f2001GL014357&partnerID=40&md5=e3790cc0a3959a1e0dec05d503b56f05","Anthropogenic aerosols can influence the climate indirectly by changing the optical properties and precipitation formation of water clouds. An indirect effect that has not been considered involves the subset of anthropogenic aerosols that act as ice nuclei and thereby determines the lifetime of ice and mixed-phase clouds. If, in addition to mineral dust, a fraction of the hydrophilic soot aerosol particles is assumed to act as contact ice nuclei as evident from recent laboratory studies, then increases in aerosol concentration from pre-industrial times to present-day pose a new indirect effect, a ""glaciation indirect effect"", on clouds. Here increases in contact ice nuclei in the present-day climate result in more frequent glaciation of clouds and increase the amount of precipitation via the ice phase. This effect can at least partly offset the solar indirect aerosol effect on water clouds."
"7403508241;7004325649;7102731389;7407116104;7403282069;","The Iris hypothesis: A negative or positive cloud feedback?",2002,"10.1175/1520-0442(2002)015<0003:tihano>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036465051&doi=10.1175%2f1520-0442%282002%29015%3c0003%3atihano%3e2.0.co%3b2&partnerID=40&md5=40fa5c52c42b03fb5535bc78260ce775","Using the Tropical Rainfall Measuring Mission (TRMM) satellite measurements over tropical oceans, this study evaluates the iris hypothesis recently proposed by Lindzen et al. that tropical upper-tropospheric anvils act as a strong negative feedback in the global climate system. The modeled radiative fluxes of Lindzen et al. are replaced by the Clouds and the Earth's Radiant Energy System (CERES) directly observed broadband radiation fields. The observations show that the clouds have much higher albedos and moderately larger longwave fluxes than those assumed by Lindzen et al. As a result, decreases in these clouds would cause a significant but weak positive feedback to the climate system, instead of providing a strong negative feedback."
"57203400519;55207447000;6701743200;56316186300;","Aerosol influence on cloud microphysics examined by satellite measurements and chemical transport modeling",2002,"10.1175/1520-0469(2002)059%3C0714%3AAIOCME%3E2.0.C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036321587&doi=10.1175%2f1520-0469%282002%29059%253C0714%253AAIOCME%253E2.0.C&partnerID=40&md5=4d870c5ce43a5d3cb898837d03379362","Anthropogenic aerosols are hypothesized to decrease cloud drop radius and increase cloud droplet number concentration enhancing cloud optical depth and albedo. Here results have been used from a chemical transport model driven by the output of a numerical weather prediction model to identify an incursion of sulfate-laden air from the European continent over the mid-North Atlantic under the influence of a cutoff low pressure system during 2-8 April 1987. Advanced Very High Resolution Radiometer (AVHRR) measurements of visible and near-infrared radiance are used to infer microphysical properties of low-altitude (T 5 260-275K) maritime clouds over the course of the event. Examination of the cloud optical depth, drop radius, and drop number concentration on the high- and low-sulfate days has allowed identification of the increase in cloud droplet number concentration and decrease in cloud drop radius associated with the sulfate incursion. These observations are consistent with the Twomey mechanism of indirect radiative forcing of climate by aerosols. © 2002 American Meteorological Society."
"7003478309;7005399437;7005793702;55725404100;35464731600;35468686100;55947099700;7004299722;","Variability of absorption and optical properties of key aerosol types observed in worldwide locations",2002,"10.1175/1520-0469(2002)059%3C0590%3AVOAAOP%3E2.0.C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036321634&doi=10.1175%2f1520-0469%282002%29059%253C0590%253AVOAAOP%253E2.0.C&partnerID=40&md5=2dc0a040cc1ccaf8ca22ad34ebd9e6b1","Aerosol radiative forcing is a critical, though variable and uncertain, component of the global climate. Yet climate models rely on sparse information of the aerosol optical properties. In situ measurements, though important in many respects, seldom provide measurements of the undisturbed aerosol in the entire atmospheric column. Here, 8 yr of worldwide distributed data from the AERONET network of ground-based radiometers were used to remotely sense the aerosol absorption and other optical properties in several key locations. Established procedures for maintaining and calibrating the global network of radiometers, cloud screening, and inversion techniques allow for a consistent retrieval of the optical properties of aerosol in locations with varying emission sources and conditions. The multiyear, multi-instrument observations show robust differentiation in both the magnitude and spectral dependence of the absorption-a property driving aerosol climate forcing, for desert dust, biomass burning, urban-industrial, and marine aerosols. Moreover, significant variability of the absorption for the same aerosol type appearing due to different meteorological and source characteristics as well as different emission characteristics are observed. It is expected that this aerosol characterization will help refine aerosol optical models and reduce uncertainties in satellite observations of the global aerosol and in modeling aerosol impacts on climate. © 2002 American Meteorological Society."
"7003800456;8263760800;6701338417;7004214645;","Impact of future climate and emission changes on stratospheric aerosols and ozone",2002,"10.1175/1520-0469(2002)059%3C0414%3AIOFCAE%3E2.0.C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036328636&doi=10.1175%2f1520-0469%282002%29059%253C0414%253AIOFCAE%253E2.0.C&partnerID=40&md5=d3f4821e1a689ad728f59771f3c35883","Global climatological distributions of key aerosol quantities (extinction, optical depth, mass, and surface area density) are shown in comparison with results from a three-dimensional global model including stratospheric and tropospheric aerosol components. It is shown that future trends in global and regional anthropogenic emissions of sulfur dioxide may induce substantial changes in the lower stratospheric budget of sulfate aerosols: with the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios' (SRES) upper limit, ""A2""scenario, the integrated stratospheric sulfate mass is predicted to increase from 0.15 Tg-S to 0.20 Tg-S in the year 2030, and the 1.02-μm average optical depth from 1.5 × 102-3 to 2.2 × 102-3 with a 50% increase in shortwave radiative forcing. The latter, in turn, is found to be about 23% of the total forcing by sulfate aerosols (tropospheric 1 stratospheric). Convective upward transport of sulfur dioxide to the tropical tropopause is found to be a key point for understanding the global distribution of sulfate in the lower stratosphere. Large increases of anthropogenic sulfur production at tropical latitudes by developing countries may explain these rather large predicted changes of stratospheric sulfate. Effects of future climate changes on stratospheric aerosols are also discussed: it is shown that the largest perturbation is on the probability of polar stratospheric cloud (PSC) formation, and that is driven primarily by greenhouse gas-induced temperature changes. In particular, the model-calculated wintertime Arctic increase of total aerosol optical depth is close to a factor of 2, with PSC optical depth and surface area density increasing by a factor of 5. This is mainly due to the predicted decrease of sudden stratospheric warming frequency in the Northern Hemisphere and the associated higher stability of the polar vortex. Enhanced ozone losses result from faster heterogeneous chemical reactions on both sulfate and PSC aerosol surfaces. The chemically driven total ozone recovery in 2030 relative to 2000 is predicted to decrease from +4.5% to +3.7% when taking into account both climate and surface emission changes: effects related to climate changes (perturbed stratospheric circulation, water vapor distribution, PSC frequency, etc.) account for about 2/3 of the calculated slow down of the O3 recovery rate. © 2002 American Meteorological Society."
"35464731600;55947099700;7005399437;7006421484;7004174939;7005793702;7202772338;6603044644;","Aerosol radiative impact on spectral solar flux at the surface, derived from principal-plane sky measurements",2002,"10.1175/1520-0469(2002)059%3C0635%3AARIOSS%3E2.0.C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036325310&doi=10.1175%2f1520-0469%282002%29059%253C0635%253AARIOSS%253E2.0.C&partnerID=40&md5=cba7c7873be622198860fba35c910cae","Accurate measurements of the spectral solar flux reaching the surface in cloud-free conditions are required to determine the aerosol radiative impact and to test aerosol models that are used to calculate radiative forcing of climate. Spectral flux measurements are hampered in many locations by persistent broken cloud fields. Here a new technique is developed to derive the diffuse solar spectral flux reaching the surface from principal-plane measurements conducted in the last six years by the Aerosol Robotic Network (AERONET). This 50-100 instrument global network measures the principal-plane radiances in four spectral bands (0.44-1.02 μm) approximately every hour every day. These instruments also measure the spectral optical thickness and derive the aerosol size distribution and other properties from sky measurements. The advantage of the AERONET measurements is that collimated sky radiance is measured for each 1° 1° field of view. Clouds and cloud shadows are rejected before the total sky brightness is reconstructed and the flux is derived. The results compare favorably with shadow band measurements and with aerosol models. Studied are smoke aerosol in Brazil; Saharan dust in Cape Verde; and urban-industrial pollution in Créteil, near Paris, France, and near Washington, D.C. The spectral attenuation of total (diffuse1direct) solar flux reaching the surface is given by f λ = exp(-aλ -2 bλτλ), where aλ is attenuation by an atmosphere with no aerosol and bλ is the aerosol attenuation coefficient. Remarkably, it is found that for these sites except for the Washington, D.C., site, the spectrally averaged value of bλ does not vary significantly from one aerosol type to another: {bλ} = 0.35 ± 0.03 (for solar zenith angle of 50°). The measured 24-h average aerosol impact on the solar flux at the surface per unit optical thickness is ΔF/ΔDτ = -80 W m-2 in these sites, almost independent of the aerosol type: smoke, dust, or urban-industrial pollution. In Washington, D.C., it is suspected, and demonstrated in a back of the envelope calculation, that the high amount of broken cloudiness and its correlation with the aerosol optical thickness are responsible for the apparent small aerosol forcing at the surface of ΔF/Δτ = -50 W m-2. © 2002 American Meteorological Society."
"26643440200;7003899619;","Evaluating the potential for retrieving aerosol optical depth over land from AVHRR pathfinder atmosphere data",2002,"10.1175/1520-0469(2002)059%3C0279%3AETPFRA%3E2.0.C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036326230&doi=10.1175%2f1520-0469%282002%29059%253C0279%253AETPFRA%253E2.0.C&partnerID=40&md5=88304086e44e1dfda5cecf167331a087","In spite of numerous studies on the remote sensing of aerosols from satellites, the magnitude of aerosol climate forcing remains uncertain. However, data from the Advanced Very High Resolution Radiometer (AVHRR) Pathfinder-Atmosphere (PATMOS) dataset-a statistical reduction of more than 19yr of AVHRR data (1981- 2000)-could provide nearly 20yr of aerosol history. PATMOS data have a daily 110 × 110 km2 equal-area grid that contains means and standard deviations of AVHRR observations within each grid cell. This research is a first step toward understanding aerosols over land with PATMOS data. Herein, the aerosol optical depth is retrieved over land at numerous Aerosol Robotic Network (AERONET) sites around the globe using PATMOS cloud-free reflectances. First, the surface bidirectional reflectance distribution function (BRDF) is retrieved using a lookup table created with a radiative transfer model and the Rahman BRDF. Aerosol optical depths are then retrieved using the retrieved BRDF parameters and the PATMOS reflectances assuming a globally constant aerosol model. This method is applied to locations with ground truth measurements, where comparisons show that the best retrievals are made by estimating the surface reflectance using observations grouped by month. Random errors (i.e., correlation coefficients and standard error of estimate) in this case are lower than those where the surface BRDF is allowed year-to-year variations. By grouping the comparison results by land cover type, it was found that less noise is expected over forested regions, with a significant potential for retrieval for 80% of all land surfaces. These results and analyses suggest that the PATMOS data can provide valuable information on aerosols over land. © 2002 American Meteorological Society."
"7102604282;56099064600;7102517130;7201496259;7003931528;7404544551;6603434295;57208462871;57210717445;6603930943;56249704400;7006074773;57203053317;7005002831;7404243086;7003800456;7003543851;56250185400;7003899619;","A comparison of model- and satellite-derived aerosol optical depth and reflectivity",2002,"10.1175/1520-0469(2002)059%3C0441%3AACOMAS%3E2.0.C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036322127&doi=10.1175%2f1520-0469%282002%29059%253C0441%253AACOMAS%253E2.0.C&partnerID=40&md5=1699eb77bddfef6406a3c3afc2a6ebff","The determination of an accurate quantitative understanding of the role of tropospheric aerosols in the earth's radiation budget is extremely important because forcing by anthropogenic aerosols presently represents one of the most uncertain aspects of climate models. Here the authors present a systematic comparison of three different analyses of satellite-retrieved aerosol optical depth based on the Advanced Very High Resolution Radiometer (AVHRR)-measured radiances with optical depths derived from six different models. Also compared are the model-derived clear-sky reflected shortwave radiation with satellite-measured reflectivities derived from the Earth Radiation Budget Experiment (ERBE) satellite. The three different satellite-derived optical depths differ by between 20.10 and 0.07 optical depth units in comparison to the average of the three analyses depending on latitude and month, but the general features of the retrievals are similar. The models differ by between 20.09 and 10.16 optical depth units from the average of the models. Differences between the average of the models and the average of the satellite analyses range over 20.11 to 10.05 optical depth units. These differences are significant since the annual average clear-sky radiative forcing associated with the difference between the average of the models and the average of the satellite analyses ranges between 23.9 and 0.7 W m-2 depending on latitude and is 21.7 W m-2 on a global average annual basis. Variations in the source strengths of dimethylsulfide-derived aerosols and sea salt aerosols can explain differences between the models, and between the models and satellite retrievals of up to 0.2 optical depth units. The comparison of model-generated reflected shortwave radiation and ERBE-measured shortwave radiation is similar in character as a function of latitude to the analysis of modeled and satellite-retrieved optical depths, but the differences between the modeled clear-sky reflected flux and the ERBE clear-sky reflected flux is generally larger than that inferred from the difference between the models and the AVHRR optical depths, especially at high latitudes. The difference between the mean of the models and the ERBE-analyzed clear-sky flux is 1.6 W m-2. The overall comparison indicates that the model-generated aerosol optical depth is systematically lower than that inferred from measurements between the latitudes of 10° and 30°S. It is not likely that the shortfall is due to small values of the sea salt optical depth because increases in this component would create modeled optical depths that are larger than those from satellites in the region north of 308N and near 508S. Instead, the source strengths for DMS and biomass aerosols in the models may be too low. Firm conclusions, however, will require better retrieval procedures for the satellites, including better cloud screening procedures, further improvement of the model's treatment of aerosol transport and removal, and a better determination of aerosol source strengths. © 2002 American Meteorological Society."
"7402702485;7801536716;","Application of a model to predict cyanobacterial growth patterns in response to climatic change at Farmoor Reservoir, Oxfordshire, UK",2002,"10.1016/S0048-9697(01)00929-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037160479&doi=10.1016%2fS0048-9697%2801%2900929-9&partnerID=40&md5=1cdfc9ce603893234a1f0a94219d1522","The cyanobacterial growth for the next 90 years at Farmoor Reservoir, Oxfordshire is predicted using the cyanobacterial growth model, CLAMM, with data obtained from HADCM2 climate change model. It is predicted that solar radiation at the water-body surface will decrease slightly due to increased cloud cover. Predictions of cyanobacterial growth indicate little change in total production although the main summer growing season may be extended. It is also suggested that increased wind velocities may affect the frequency of 'blooming incidents'. © 2002 Elsevier Science B.V. All rights reserved."
"7005966519;","South and southeast Brazilian grasslands during Late Quaternary times: A synthesis",2002,"10.1016/S0031-0182(01)00349-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037022035&doi=10.1016%2fS0031-0182%2801%2900349-2&partnerID=40&md5=c7993b7f76163c9d5ee8479ab271dcae","Fourteen pollen records from the south (S) and the southeast (SE) Brazilian regions have been synthesised. Late Glacial records from S Brazilian highlands document the predominance of grassland (campos) where today Araucaria forests occur. Records from SE Brazil show that during pre- and full-glacial times modern tropical semideciduous forest and cerrado (savanna to dry forest) were mostly replaced by grassland and some subtropical gallery forest. Modern montane Araucaria forests and cloud forests in SE Brazil were mostly replaced by grassland during pre- and full-glacial times. There is evidence that the modern tropical Atlantic rainforest in S Brazil was significantly reduced and replaced by cold-adapted forest taxa or grassland during glacial, especially during full-glacial times. The synthesis indicates that grasslands dominated the S and SE Brazilian landscape during the Late Pleistocene where today different forest ecosystems exist. Grassland extended over 750 km from S to SE Brazil from latitudes of about 28°/27° S to at least 20° S. These results indicate that climates in the region were markedly drier and 5-7°C cooler during glacial times. Antarctic cold fronts must have been much stronger and more frequent than today. Studies from S Brazil show that huge areas of Late Pleistocene campos vegetation were still found on the S Brazilian highlands during early and mid Holocene times, reflecting dry climatic conditions with an annual dry period of probably 3 months. Modern wet climatic conditions with no or only short dry periods were not established until the Late Holocene period when Araucaria forests replaced large areas of grassland vegetation after about 3000 14C yr B.P. and especially after 1500/1000 14C yr B.P. © 2002 Elsevier Science B.V. All rights reserved."
"6603422104;7006698304;","Evaluation of midlatitude cloud properties in a weather and a climate model: Dependence on dynamic regime and spatial resolution",2002,"10.1029/2002JD002259","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0242593344&doi=10.1029%2f2002JD002259&partnerID=40&md5=807ec14ececcb5e006d863c8cdcc8885","In this study, the midlatitude cloud fields produced by a climate (GISS) and a weather (ECMWF) model are evaluated against satellite observations. Monthly ensembles of model cloud property distributions for the four seasons are compared with similar ensembles from satellite retrievals. The weather model is run in both forecast and ""climate"" mode in order to evaluate the importance of the exact representation of the atmospheric conditions in these ensemble comparisons. The weather and climate models are evaluated at different resolutions that cover the range used in today's climate and weather prediction simulations. Cloud property evaluations are separated into broadly defined dynamic regimes that cover the range of large-scale midlatitude motions. Quantitative evaluation tables are produced that rank the performance of the different model versions used in the study. The evaluation analysis reveals several common features between the two models. Those are the overestimation of cloud optical depth in all dynamic regimes, the underestimation of cloud cover in the large-scale descent regime and the underestimation of cloud top height in the large-scale descent regime. It is also shown that, in the radiative balance calculations, the models compensate for the overestimation of cloud optical depth through the underprediction of cloud cover. The comparison of the forecast and ""climate"" runs of the ECMWF model shows remarkably similar statistical properties of the clouds in the two runs. The analysis of runs with different resolutions reveals large improvement when going from a 4° × 5° 9-layer to a 2° × 2.5° 32-layer run with the GISS GCM, much of which is caused by the increase in vertical resolution. A comparison of a T42 and a T106 run of the same vertical resolution with the ECMWF GCM does not show considerable differences between the two model versions. Copyright 2002 by the American Geophysical Union."
"6701657620;7006235542;7410084319;7006346149;","Use of an explicit model of the microphysics of precipitating stratiform cloud to test a bulk microphysics scheme",2002,"10.1256/003590002321042108","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036131350&doi=10.1256%2f003590002321042108&partnerID=40&md5=510738981020b869164224b4d34a829e","An explicit microphysical model is used to study the development of nimbostratus cloud. The model contains a simple representation of embedded convection. The results show that secondary ice processes can be important in determining the ice and liquid-water contents of the cloud, especially when embedded convection is switched on. The results are used to test the bulk microphysical parametrization that is used in a state-of-the-art climate model, by running the bulk scheme within the same dynamical framework as the explicit scheme. Compared with the explicit scheme, the bulk scheme overestimates the ice and underestimates the liquid-water content compared with the explicit scheme. To parametrize the secondary ice processes effectively, the bulk scheme will require representation of small ice crystals."
"7005955015;","Studies of the aerosol indirect effect from sulfate and black carbon aerosols",2002,"10.1029/2001JD000887","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347811386&doi=10.1029%2f2001JD000887&partnerID=40&md5=e219ae921a4fbb080404483019bd0613","The indirect effect of anthropogenic aerosols is investigated using the global climate model National Center for Atmospheric Research Community Climate Model Version 3 (NCAR CCM3). Two types of anthropogenic aerosols are considered, i.e., sulfate and black carbon aerosols. The concentrations and horizontal distributions of these aerosols were obtained from simulations with a life-cycle model incorporated into the global climate model. They are then combined with size-segregated background aerosols. The aerosol size distributions are subjected to condensation, coagulation, and humidity swelling. By making assumptions on supersaturation, we determine cloud droplet number concentrations in water clouds. Cloud droplet sizes and top of atmosphere (TOA) radiative fluxes are in good agreement with satellite observations. Both components of the indirect effect, i.e., the radius and lifetime effects, are computed as pure forcing terms. Using aerosol data for 2000 from the Intergovernmental Panel on Climate Change (IPCC), we find, globally averaged, a 5% decrease in cloud droplet radius and a 5% increase in cloud water path due to. anthropogenic aerosols. The largest changes are found over SE Asia, followed by the North Atlantic, Europe, and the eastern United States. This is also the case for the radiative forcing (""indirect effect""), which has a global average of -1.8 W m-2. When the experiment is repeated using data for 2100 from the IPCC A2 scenario, an unchanged globally averaged radiative forcing is found, but the horizontal distribution has been shifted toward the tropics. Sensitivity experiments show that the radius effect is ∼3 times as important as the lifetime effect and that black carbon only contributes marginally to the overall indirect effect. Copyright 2002 by the American Geophysical Union."
"6602831555;6602332696;7004194999;","Contrails in a comprehensive global climate model: Parameterization and radiative forcing results",2002,"10.1029/2001JD000429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-32044434212&doi=10.1029%2f2001JD000429&partnerID=40&md5=b55374a078631659b2c39477e3d5df69","A parameterization of contrails for use in comprehensive global climate models is introduced. It is based on the thermodynamic theory of contrail formation, which has been applied in a consistent way with the cloud parameterization scheme of the version 4 European Center/Hamburg General Circulation Model. Both the coverage and the optical properties of contrails are calculated as functions of instantaneous values of atmospheric variables as they are provided by the climate model. The resulting spatial distributions of contrail parameters prove to be useful for explaining observed differences between contrails in different geographical regions. The time mean properties of the simulated contrails are in fair agreement with observations, though the values of ice water path and optical depth tend to be somewhat lower than those reported from in situ measurements. The radiative forcing of contrails resulting from the climate model experiments is substantially lower than estimated in a previous study, where mean parameters for contrails and the ambient atmosphere were prescribed in a radiative transfer model. One contribution to this disagreement arises from the smaller mean ice water content in the climate model simulations. However, the largest part must be related to a different treatment of the interference of contrails with natural high clouds. The sensitivity of the contrail radiative forcing to systematic errors in simulated ambient atmospheric variables (like temperature, humidity, and natural clouds) as well as to the parameterization of cloud and contrail overlap needs to be investigated further. Copyright 2002 by the American Geophysical Union."
"25652514900;7403296332;","Parameterization of Longwave Optical Properties for Water Clouds",2002,"10.1007/s00376-002-0031-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347305502&doi=10.1007%2fs00376-002-0031-y&partnerID=40&md5=28306f9bbbfe10cff700d4de14aa2bad","Based on relationships between cloud microphysical and optical properties, three different parameterization schemes for narrow and broad band optical properties in longwave region for water clouds have been presented. The effects of different parameterization schemes and different number of broad bands used on cloud radiative properties have been investigated. The effect of scattering role of cloud drops on longwave radiation fluxes and cooling rates in cloudy atmospheres has also been analyzed."
"7801454916;7004013739;6602806333;6507040878;6507515551;6701410329;7201472576;7006681376;7102661811;55798653600;6505511524;6506224867;","The satellite application facility on climate monitoring",2002,"10.1016/S0273-1177(02)80290-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036875060&doi=10.1016%2fS0273-1177%2802%2980290-3&partnerID=40&md5=f5fcb2b695ec003b792b178333f9ab8b","The Satellite Application Facility on Climate Monitoring is a joint project of the National Meteorological Services and other institutes from Belgium, Finland, Germany, Sweden and The Netherlands. The objective of the project is to set up a system to provide atmospheric and oceanographic data sets from (primarily) operational geostationary and polar orbiting meteorological satellites for climate monitoring, research and applications at regional European scale, for some products on a global scale. Initial operational SAF products are related to clouds, radiation budget, ocean status and water vapour content in the atmosphere. SAF operations are foreseen to start in 2004. © 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved."
"35552588700;","Amelioration of global warming by controlled enhancement of the albedo and longevity of low-level maritime clouds",2002,"10.1006/asle.2002.0048","https://www.scopus.com/inward/record.uri?eid=2-s2.0-4143124516&doi=10.1006%2fasle.2002.0048&partnerID=40&md5=ffe8f921a1a33b9fa3f19f98eb0a26ca","A technique is proposed for controlled enhancement of droplet concentrations in low-level maritime clouds, with corresponding increase in their albedo and longevity, thereby producing a cooling effect. It involves dissemination at the ocean surface of small seawater droplets which act as cloud condensation nuclei (CCN). It has low ecological impact. © 2002 Royal Meteorological Society."
"7005955015;","Studies of the aerosol indirect effect from sulfate and black carbon aerosols",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448997395&partnerID=40&md5=741b44403b556c61acf95ee1c37ec402","[1] The indirect effect of anthropogenic aerosols is investigated using the global climate model National Center for Atmospheric Research Community Climate Model Version 3 (NCAR CCM3). Two types of anthropogenic aerosols are considered, i.e., sulfate and black carbon aerosols. The concentrations and horizontal distributions of these aerosols were obtained from simulations with a life-cycle model incorporated into the global climate model. They are then combined with size-segregated background aerosols. The aerosol size distributions are subjected to condensation, coagulation, and humidity swelling. By making assumptions on supersaturation, we determine cloud droplet number concentrations in water clouds. Cloud droplet sizes and top of atmosphere (TOA) radiative fluxes are in good agreement with satellite observations. Both components of the indirect effect, i.e., the radius and lifetime effects, are computed as pure forcing terms. Using aerosol data for 2000 from the Intergovernmental Panel on Climate Change (IPCC), we find, globally averaged, a 5% decrease in cloud droplet radius and a 5% increase in cloud water path due to anthropogenic aerosols. The largest changes are found over SE Asia, followed by the North Atlantic, Europe, and the eastern United States. This is also the case for the radiative forcing (""indirect effect""), which has a global average of -1.8 W m-2. When the experiment is repeated using data for 2100 from the IPCC A2 scenario, an unchanged globally averaged radiative forcing is found, but the horizontal distribution has been shifted toward the tropics. Sensitivity experiments show that the radius effect is ∼3 times as important as the lifetime effect and that black carbon only contributes marginally to the overall indirect effect. Copyright 2002 by the American Geophysical Union."
"7006211890;7202330299;7202444684;7103313899;6603019259;6506887943;6603343882;","Two case studies of winter continental-type water and mixed-phase stratocumuli over the sea 1. Microphysical and optical properties",2002,"10.1029/2001JD001106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84905411053&doi=10.1029%2f2001JD001106&partnerID=40&md5=24dd484d7e6252b64445fdbcf44bb14f","Collocated aircraft observations of microstructure and radiative properties of winter boundary layer clouds over the East China Sea and the Japan Sea have been carried out in January 1999 within the Japanese Cloud and Climate Study (JACCS) program. The first part of the paper describes the in situ measured microphysical and optical properties for two cases of boundary layer winter stratocumulus clouds, which concern, first, a rather uniform, supercooled water cloud contaminated by aerosols and, second, a highly heterogeneous, mixed-phase stratiform cloud, Using the Polar Nephelometer, a new instrument for measuring, in situ, the scattering phase function of cloud droplets and ice particles, the polluted, continental-type stratocumulus cloud can be optically regarded as a liquid water cloud because the measured scattering phase functions fitted very well with those calculated from Mie theory for the directly measured FSSP size distributions. In mixed-phase cloud, the measured scattering phase function shows that ice particles strongly affect optical properties of the cloud, where large number of liquid water droplets with higher extinction coefficient and asymmetry factor values were converted into a much smaller number of large ice crystals with lower extinction coefficient and asymmetry factor. Furthermore, a quasi-stable liquid-topped cloud layer with precipitating ice particles was noticed; the layer may, first, affect the cloud radiative properties and, second, seriously restrict the interpretation of satellite cloud composition retrievals. Copyright 2002 by the American Geophysical Union."
"57214899685;57203053317;7403508241;","A new statistically based autoconversion rate parameterization for use in large-scale models",2002,"10.1029/2001JD001484","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448950866&doi=10.1029%2f2001JD001484&partnerID=40&md5=c90ec0a82a4d736e0f77d5c0a09df3b3","The autoconversion rate is a key process for the formation of precipitation in warm clouds. In climate models, physical processes such as autoconversion rate, which are calculated from grid mean values, are biased, because they do not take subgrid variability into account. Recently, statistical cloud schemes have been introduced in large-scale models to account for partially cloud-covered grid boxes. However, these schemes do not include the in-cloud variability in their parameterizations. In this paper, a new statistically based autoconversion rate considering the in-cloud variability is introduced and tested in three cases using the Canadian Single Column Model (SCM) of the global climate model. The results show that the new autoconversion rate improves the model simulation, especially in terms of liquid water path in all three case studies. Copyright 2002 by the American Geophysical Union."
"35566782000;6505655310;36864279000;6602847318;14035659000;","Cloud field assimilation using simulated Triana satellite data",2002,"10.1016/S0273-1177(02)80302-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036875498&doi=10.1016%2fS0273-1177%2802%2980302-7&partnerID=40&md5=0572ed0b2d934c0473eebf55167ed850","In the next few years, NASA plans to launch satellite Triana, a deep space Earth observatory that will take a full-disk view of the sunlit side of the Earth. Triana carries two instruments, EPIC, which will deliver Science products such as total precipitable water, cloud height, aerosol index, total ozone, and a global visible cloud field image, and NISTAR, which obtains precise radiometry integrated over the entire sunlit disk. Using a contemporary atmospheric model (namely the Eta model), we have started a project whose goal is to simulate some of the Triana observations and to assess the impact of Triana data for weather and climate predictions. In this paper, we report on the results of numerical experiments assimilating temperature profiles with and without cloud liquid water for inferring tropical arid extra-tropical atmospheric states. We also assess the impact of initializing cloud liquid water for short term forecasts and data assimilation cycles. Published by Elsevier Science Ltd on behalf of COSPAR."
"7201844203;7005548544;7006957668;","Reply to: ""Tropical cirrus and water vapor: an effective Earth infrared iris feedback?""",2002,"10.5194/acp-2-99-2002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-52649094243&doi=10.5194%2facp-2-99-2002&partnerID=40&md5=ffa2e10c4b63475c8ea000b482573bbc","In assessing the iris effect suggested by Lindzen et al. (2001), Fu et al. (2002) found that the response of high-level clouds to the sea surface temperature had an effect of reducing the climate sensitivity to external radiative forcing, but the effect was not as strong as LCH found. The approach of FBH to specifying longwave emission and cloud albedos appears to be inappropriate, and the derived cloud optical properties may not have real physical meaning. The cloud albedo calculated by FBH is too large for cirrus clouds and too small for boundary layer clouds, which underestimates the iris effect. © European Geophysical Society 2002."
"26643250500;57203053317;","A parameterization of cirrus cloud formation: Homogeneous freezing including effects of aerosol size",2002,"10.1029/2001JD001429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-18144449447&doi=10.1029%2f2001JD001429&partnerID=40&md5=d372b2c88f30330eb0f6c124dd294b71","In a previous study, we have derived an approximate, physically based parameterization of cirrus cloud formation by homogeneous freezing, applying to a wide class of supercooled aerosols in the upper troposphere and tropopause region. In this study, the parameterization scheme is extended to include the effects of aerosol size on the freezing process in adiabatically rising air parcels. Aerosol size effects become important when the timescale of the freezing event is fast compared to the timescale of depositional growth of the pristine ice particles. The generalized parameterization scheme is validated with parcel model simulations and can directly be applied in models that do not explicitly resolve the ice nucleation process, such as cloud-resolving models, weather forecast models, and climate models. The relationship between aerosol and ice crystal number concentrations in cirrus clouds formed by homogeneous freezing is discussed. This relationship is much weaker than in liquid water clouds. It is shown that even freezing of enhanced levels of sulfate aerosol originating from strong volcanic eruptions is unlikely to exert a sensible influence on cirrus formation. Copyright 2002 by the American Geophysical Union."
"35237545900;35235591200;6603626125;36771348400;7202806738;7103188403;","Reduction in sunshine duration over Taiwan: Causes and implications",2002,"10.3319/TAO.2002.13.4.523(A)","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036995808&doi=10.3319%2fTAO.2002.13.4.523%28A%29&partnerID=40&md5=21e1db60948101fadb4360ef9de0a320","Long-term records (about 100 years) of meteorological parameters of Taiwan have been analyzed to study causes and implications of decreasing trends in sunshine duration observed during Taiwan's rapid economic developing period that started in the 1960's. Although the largest decreasing trends in sunshine duration are found in major urban centers, in-depth analysis shows that the reductions are surprisingly uniform and well correlated among stations throughout Taiwan and her surrounding islands, implying that direct scattering by aerosols is not the major cause of the reductions. Similar reductions occur at two high altitude stations, namely Alishan (2.4 km) and Yushan (3.85 km), suggesting that the cause of the reductions is at altitude above 3.85 km. After eliminating other potential causes, we hypothesize that the trends are most likely caused by an increase in regional clouds and/or cloud albedo as a result of increased anthropogenic aerosols. The extent of the region depends on the season. Strong westerlies above 3.85 km in winter and spring imply that southern China, Southeast Asia, India and regions further upwind may suffer similar reductions and could be the major source of anthropogenic aerosols. In summer and fall, the wind pattern indicates Taiwan's own emissions of aerosols can play a significant role in the reduction. Potential ramifications of the increase in clouds/cloud albedo to regional climate change are serious. The increase in clouds/cloud albedo obviously has lead to a decrease in the diurnal temperature range. These changes may also be linked to an increase in precipitation intensity and other observed changes in some key climate parameters in Taiwan."
"24376360400;7005776035;","The impact of cloud cover on the net radiation budget of the Greenland ice sheet",2002,"10.3189/172756402781817789","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036336647&doi=10.3189%2f172756402781817789&partnerID=40&md5=ca0b4cd5a87bcc77705a96c01d3eb16e","Energy-balanced models driven by radiation and turbulent heat fluxes have been widely applied to predicting the response of the Greenland ice sheet to climate change. However, a lack of knowledge of the temporal and spatial distribution of cloud amount and type has necessitated the use of parameterizations or statistical models of cloud cover. This deficiency results in large uncertainties in both shortwave and longwave radiation fluxes. Stereo-matching of nadir and forward view Along Track Scanning Radiometer-2 (ATSR-2) image pairs has been shown to be a reliable method of retrieving cloud top height, and further cloud properties can be derived from thermal imagery allowing classification into cloud type. A 1 year cloud record for a transect across southern Greenland derived from stereo-matching is presented here, and comparisons are made with climate re-analysis data and ground observations. The cloud-cover data were used in a simple radiative transfer model, and the impact of clouds on the net radiation fluxes was found to be considerable. Different cloud scenarios produced up to 40 W m 2 difference in net radiation balance. In the ablation zone, where the albedo is lower and most variable, the sensitivity to cloud-cover fraction was less marked, but the higher spatial resolution of the ATSR-2 cloud record was reflected by a much more varied trend in radiation balance. Whether the net radiation balanced increases or decreases with increased cloud cover was found to be a function of the cloud amount and type and also the surface albedo. The sensitivity of the model to a ±5% change in cloud amount was found to be comparable to a 1 K change in temperature. This clearly demonstrates the importance of reliable, quantitative cloud data in mass-balance and other glaciological studies."
"16637291100;7403931916;7201826462;6602252422;","Parameterization of shortwave ice cloud optical properties for various particle habits",2002,"10.1029/2001JD000742","https://www.scopus.com/inward/record.uri?eid=2-s2.0-32044445295&doi=10.1029%2f2001JD000742&partnerID=40&md5=b8fc116943706eb6cdbfea4ba85440a7","The relative importance of ice clouds in the climate system is highly uncertain. Measurements of their microphysical properties are sparse, especially given their complex structure and large variability in particle size, shape, and density. To better understand the role of ice clouds in the climate system, parameterizations of their radiative properties are needed. The shortwave bulk optical properties of seven ice particle shapes, or ""habits,"" are parameterized as a function of the effective ""radius"" and ice water content by integrating the scattering properties over 30 in situ size distributions. The particle habits are solid and hollow hexagonal columns, hexagonal plates, two- and three-dimensional bullet rosettes, aggregates of columns, and dendrites. Parameterizations of the volume extinction coefficient, single-scattering albedo, and the asymmetry parameter are presented for 6, 24, and 56 band shortwave schemes from 0.2 to 5.0 μm. Applications to downwelling flux and upwelling radiance calculations indicate that differences in fluxes for various habits can be more than 15%, and differences in retrievals of cloud optical depth from satellite visible reflectances can be more than 50%. Copyright 2002 by the American Geophysical Union."
"7201844203;56100874900;7403931916;","Parameterization of shortwave cloud optical properties for a mixture of ice particle habits for use in atmospheric models",2002,"10.1029/2002JD002061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037543258&doi=10.1029%2f2002JD002061&partnerID=40&md5=836e3c85e1bbf61a1f6d239c976d2d1a","On the basis of single-scattering optical properties precomputed with an improved geometric optics method, the bulk absorption coefficient, single-scattering albedo, and asymmetry factor of ice particles have been parameterized as a function of the effective particle size of a mixture of ice habits, the ice water amount, and spectral band. The parameterization has been applied to computing fluxes for sample clouds with various particle size distributions and assumed mixtures of particle habits. It is found that flux calculations are not overly sensitive to the assumed particle habits if the definition of the effective particle size is consistent with the particle habits on which the parameterization is based. Otherwise, the error in the flux calculations could reach a magnitude unacceptable for climate studies. Different from many previous studies, the parameterization requires only an effective particle size representing all ice habits in a cloud layer but not the effective size of individual ice habits. Copyright 2002 by the American Geophysical Union."
"6603809220;57203053317;","Simulation of the tropospheric sulfur cycle in a global model with a physically based cloud scheme",2002,"10.1029/2002JD002128","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751293143&doi=10.1029%2f2002JD002128&partnerID=40&md5=d27b2ec25f130fcf83de400d2365d67e","The treatment of the sulfur cycle in the CSIRO global climate model (GCM) is described. It is substantially based on the scheme developed previously for me EuropeanCenter/Hamburg (ECHAM) model, but the treatment of wet scavenging has been completely rewritten to better reflect the different properties of liquid and frozen precipitation, and the treatment of these in the model's cloud microphysical scheme. The model is able to reproduce the observed finding that wet deposition of sulfur over Europe and North America is larger in summer than in winter, but the seasonal cycle of sulfate over Europe is not well simulated. The latter is improved when the amplitude of the seasonal cycle of European emissions is increased. Below-cloud scavenging makes an important contribution in our scheme: On omitting it, the global sulfate burden increases from 0.67 to 0.93 Tg S. On reverting to the less efficient scavenging treatment used in ECHAM, the global sulfate burden again increases from 0.67 to 0.93 Tg S, and excessive sulfate concentrations are obtained in Europe and North America. Some deficiencies in the simulation are investigated via further sensitivity tests. In particular, during the Arctic winter, the modeled sulfur dioxide (SO2) concentrations are too large, and the modeled sulfate concentrations are too small (as in most global sulfur-cycle models). Recent laboratory experiments suggest that SO<inf>2</inf> oxidation in ice clouds is nonnegligible. We obtain a much improved Arctic simulation when a simple treatment ot SO<inf>2</inf> oxidation in ice clouds is included. Copyright 2002 by the American Geophysical Union."
"7402565763;7003842561;","Cloud condensation nuclei spectra and polluted and clean clouds over the Indian Ocean",2002,"10.1029/2001JD000829","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1642357684&doi=10.1029%2f2001JD000829&partnerID=40&md5=91c164a6f1cf7b6c9fdb8fa8bb1b373e","Cloud condensation nuclei (CCN) and cloud microphysics measurements with various levels of pollution over the Indian Ocean showed roughly linear relationships. Estimates of adiabatic cloud droplet concentrations make more useful comparisons than average droplet concentrations, which are reduced by entrainment and averaging artifacts. Adiabatic cloud droplet estimates indicate higher cloud supersaturations. As predicted, the supersaturations were suppressed by higher CCN and cloud droplet concentrations. However, the actual suppression of cloud supersaturations was not as great as these comparisons indicated because many small cloud droplets were below the detection limit of the Forward Scattering Spectrometer Probe (FSSP), especially in the polluted air. Predictions of droplet concentrations based on CCN spectra and updraft velocities matched estimates of adiabatic cloud droplet concentrations in the clean air but overpredicted adiabatic estimates of polluted cloud droplet concentrations largely because of the undercounting of smaller droplets in polluted air masses. Thus, when all things were considered, a reasonable level of closure was found between predictions of droplet concentrations and adiabatic estimates of cloud droplet concentrations. Copyright 2002 by the American Geophysical Union."
"11141439900;","Implementation and validation of a new prognostic large-scale cloud and precipitation scheme for climate and data-assimilation purposes",2002,"10.1256/00359000260498879","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036148309&doi=10.1256%2f00359000260498879&partnerID=40&md5=e576d61dba8aeacee236068cc9183bd2","A large-scale condensation scheme, able to treat separately both atmospheric cloud condensate and precipitation content in a prognostic way, has been implemented and validated in Météo-France's operational global model, ARPEGE. The proposed scheme can be used for climate simulations and short-range numerical weather prediction, although it was originally designed for the future variational assimilation of cloud and precipitation observations. The main originalities of the scheme, compared with other existing schemes having a similar moderate level of complexity, lie in the inclusion of a prognostic variable for rain and snow content, and in the use of a simple semi-Lagrangian treatment of the fall of precipitation. The calculations of large-scale condensation/evaporation and cloud fraction are based on probability-density functions, and the parametrized microphysical processes that involve precipitation are autoconversion, collection, and evaporation/sublimation. Various observations, which include satellite data from METEOSAT and from the Defense Meteorological Satellite Program's Special Sensor Microwave Imager, have been used for validating the cloud scheme within three-dimensional ARPEGE simulations at operational resolution for cases from the Fronts and Atlantic Storm-Track Experiment. These ARPEGE simulations have also been compared with 10 km runs obtained with the Met Office's Unified Model and with the French Méso-NH research model. In addition, cloud radar, ceilometer, and lidar observations from the Atmospheric Radiation Measurement project have been utilized for validating the simulation of a synoptic winter cloud system over the southern Great Plains in the USA. The behaviour of the scheme was then assessed at a coarser resolution, with a particular focus on the zonal-mean radiative budget of the earth and the zonal-mean cloud cover. Finally, the question of the sensitivity of the results from the new scheme to various parameters has been addressed, including the time step and the specification of the fall velocities for rain and snow."
"55887849100;7201551011;","The proposed connection between clouds and cosmic rays: Cloud behaviour during the past 50-120 years",2002,"10.1016/S1364-6826(01)00105-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036130582&doi=10.1016%2fS1364-6826%2801%2900105-5&partnerID=40&md5=792a91391a79a214b9dba0bcb2464c5c","Several authors have suggested that a link exists between the flux of galactic cosmic rays (GCR) and cloudiness. Here we review the evidence for such a connection from studies of cloud factors using both satelite and ground-based data. In particular, we search for evidence for the low cloud decrease predicted by the rising levels of solar activity and the low cloud-cosmic ray flux correlation indicated by satellite data. Sunshine and synoptic cloud records both indicate that the global total cloud cover has increased during the past century. This increase in total cloud cover argues against a dominating role by solar activity (via GCR) over cloud formation on centennial time scales. Either the predicted low cloud decrease has not occurred or the medium-high level cloud has increased to a greater extent than low cloud has decreased. As there is no accurate long term data available on low cloud behaviour during the last century, we are not able to totally dismiss the link between GCR and cloudiness, but we list a number of arguments for and against the proposed cosmic ray-cloud connection. © 2002 Elsevier Science Ltd. All rights reserved."
"57203400519;55207447000;6701743200;56316186300;","Aerosol influence on cloud microphysics examined by satellite measurements and chemical transport modeling",2002,"10.1175/1520-0469(2002)059<0714:aiocme>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086811735&doi=10.1175%2f1520-0469%282002%29059%3c0714%3aaiocme%3e2.0.co%3b2&partnerID=40&md5=088e4a0dfe189649f67108a81bc4455b","Anthropogenic aerosols are hypothesized to decrease cloud drop radius and increase cloud droplet number concentration enhancing cloud optical depth and albedo. Here results have been used from a chemical transport model driven by the output of a numerical weather prediction model to identify an incursion of sulfate-laden air from the European continent over the mid-North Atlantic under the influence of a cutoff low pressure system during 2-8 April 1987. Advanced Very High Resolution Radiometer (AVHRR) measurements of visible and near-infrared radiance are used to infer microphysical properties of low-altitude (T = 260-275 K) maritime clouds over the course of the event. Examination of the cloud optical depth, drop radius, and drop number concentration on the high- and low-sulfate days has allowed identification of the increase in cloud droplet number concentration and decrease in cloud drop radius associated with the sulfate incursion. These observations are consistent with the Twomey mechanism of indirect radiative forcing of climate by aerosols."
"16637291100;7403931916;7201826462;6602252422;","Parameterization of shortwave ice cloud optical properties for various particle habits",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448992671&partnerID=40&md5=5dbe0e562b1add912ffac5148ee9c626","The relative importance of ice clouds in the climate system is highly uncertain. Measurements of their microphysical properties are sparse, especially given their complex structure and large variability in particle size, shape, and density. To better understand the role of ice clouds in the climate system, parameterizations of their radiative properties are needed. The shortwave bulk optical properties of seven ice particle shapes, or ""habits,"" are parameterized as a function of the effective ""radius"" and ice water content by integrating the scattering properties over 30 in situ size distributions. The particle habits are solid and hollow hexagonal columns, hexagonal plates, two- and three-dimensional bullet rosettes, aggregates of columns, and dendrites. Parameterizations of the volume extinction coefficient, single-scattering albedo, and the asymmetry parameter are presented for 6, 24, and 56 band shortwave schemes from 0.2 to 5.0 μm. Applications to downwelling flux and upwelling radiance calculations indicate that differences in fluxes for various habits can be more than 15%, and differences in retrievals of cloud optical depth from satellite visible reflectances can be more than 50%. Copyright 2002 by the American Geophysical Union."
"6508217970;56247939300;16192856000;","Origin of the Mount Pinatubo climactic eruption cloud: Implications for volcanic hazards and atmospheric impacts",2002,"10.1130/0091-7613(2002)030<0663:OOTMPC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874982108&doi=10.1130%2f0091-7613%282002%29030%3c0663%3aOOTMPC%3e2.0.CO%3b2&partnerID=40&md5=ae0649d9d215a71bce890b851704e419","Volcanic-ash clouds can be fed by an upward-directed eruption column (Plinian column) or by elutriation from extensive pyroclastic flows (coignimbrite cloud). There is considerable uncertainty about which mechanism is dominant in large-scale eruptions. Here we analyze in a novel way a comprehensive grain-size database for pyroclastic deposits. We demonstrate that the Mount Pinatubo climactic eruption deposits were substantially derived from coignimbrite clouds, and not only by a Plinian cloud, as generally thought. Coignimbrite ash-fall deposits are much richer in breathable <10 μm ash (5-25 wt%) than pure Plinian ash at most distances from the source volcano. We also show that coignimbrite ash clouds, as at Pinatubo, are expected to be more water rich than Plinian clouds, leading to removal of more HCI prior to stratospheric injection, thereby reducing their atmospheric impact."
"7402822814;","Altitude variations of cosmic ray induced production of aerosols: Implications for global cloudiness and climate",2002,"10.1029/2001JA000248","https://www.scopus.com/inward/record.uri?eid=2-s2.0-42549113465&doi=10.1029%2f2001JA000248&partnerID=40&md5=186b55af05fcfc47e59fdae3f6d6eb90","The indirect radiative forcing of atmospheric aerosols is sensitive to particle size and concentration, which are influenced significantly by nucleation processes. Via its role in aerosol formation, cosmic ray may affect the cloud condensation nuclei abundance and hence the global cloud properties and climate. Systematic variations in ionization rates due to the modulation of cosmic ray radiation by the solar cycle are sufficient to cause notable variations in aerosol production, and we find that the signs of such variations are altitudedependent. Our study indicates that an increase in cosmic ray fluxes generally leads to an increase in particle production in the lower troposphere but a decrease in particle production in the upper troposphere. The main reason of such an altitude-dependent influence is that the dependence of particle production rate on ionization rate is a complex function of ionization rate itself, as well as precursor gas concentration and ambient conditions. The implications of altitude variations of cosmic ray-induced aerosol production on global cloudiness and climate are discussed. In addition to the reported positive correlation between cosmic ray variations and low cloudiness, our analysis reveals that high cloudiness may be anti-correlated with cosmic ray variations if volcano and El Niño impacts are excluded. The observed different correlations between cosmic ray variations and low, middle and high cloud anomalies appear to be consistent with the predicted different sensitivities of particle production to cosmic ray changes at different altitudes. A systematic change in global cloudiness may change the atmosphere heating profile, and if confirmed, may provide the external forcing needed to reconcile the different surface and troposphere temperature trends. Much more work is needed to understand how and how much the cosmic ray variations will affect the global cloud properties and climate. Copyright 2002 by the American Geophysical Union."
"57203183278;6602835352;7202637955;6505826823;6507259997;","Mesospheric cloud observations at unusually low latitudes",2002,"10.1016/S1364-6826(02)00053-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036074903&doi=10.1016%2fS1364-6826%2802%2900053-6&partnerID=40&md5=68c1177041082c03b3ca14136ffb3689","Noctilucent clouds (NLC) are a beautiful, high-latitude, summertime phenomenon that was first reported over 100 years ago. They are seen during the hours of twilight by the scattering of sunlight from sub-micron-sized ice particles that form in the vicinity of the cold mesopause region. NLC are quite distinctive, often appearing silvery-blue in color. In recent years there has been a marked increase in their frequency of occurrence, possibly due to an increase in mesospheric water vapor and/or to a cooling of the mesopause region, prompting speculation that they are ""harbingers"" of potentially serious changes in the mesospheric climate. In concert with this trend there are also a growing number of ground-based NLC sightings at significantly lower latitudes than expected. Here we report two unusual NLC displays photographed from Logan, UT, USA (∼42°N) during June 1999, well over 10° lower in latitude than expected and implying a major, yet temporary, departure from normal mid-latitude summertime conditions. These data provide new evidence for the occasional expansion of NLC to unusually low latitudes possibly due to exceptional dynamical forcing. Alternatively, they may be an early indicator of significant long-term changes taking place in the upper mesospheric summertime environment. © 2002 Elsevier Science Ltd. All rights reserved."
"26643250500;57203053317;","A parameterization of cirrus cloud formation: Homogeneous freezing of supercooled aerosols",2002,"10.1029/2001jd000470","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086352246&doi=10.1029%2f2001jd000470&partnerID=40&md5=3e15290d8d9a39c9120d9467d47d3a26","The nucleation and initial growth of ice crystals in cirrus clouds at low (<235 K) temperatures prevailing in the upper troposphere and in the tropopause region is theoretically considered. The analysis explains the dependence of the number density of ice crystals on the vertical velocity and temperature seen in numerical simulations of cirrus formation when the timescale of depositional growth of the pristine ice particles is fast compared to the timescale of the freezing event. In such cases, applicable in many situations, the number of crystals formed via homogeneous freezing of aqueous solution droplets is rather insensitive to details of the aerosol size distribution, but increases rapidly with updraft velocity and decreases with temperature. The derived parameterization is validated with parcel model simulations, and its applicability for use in climate models is discussed. The potential role of aerosol size and heterogeneous freezing processes in altering the predicted cirrus properties is briefly addressed."
"7202330299;7103313899;7202444684;7006211890;6504755699;","Two case studies of winter continental-type water and mixed-phase stratocumuli over the sea 2. Absorption of solar radiation",2002,"10.1029/2001JD001108","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448950557&doi=10.1029%2f2001JD001108&partnerID=40&md5=e0354daf42e116bccb5a9160712e9842","We have carried out airborne experiments on cloud-radiation interactions for wintertime boundary layer clouds over the East China Sea and the Japan Sea in January 1999 as part of the Japanese Cloud and Climate Study (JACCS) program. By means of collocated and synchronized flights of two instrumented aircraft, flying above and below the cloud layer, respectively, we directly measured the visible and near-infrared (IR) solar absorption for two cases of stratiform clouds: one featuring supercooled water stratocumulus cloud polluted by continental aerosols observed on 21 January and one featuring highly inhomogeneous, mixed-phase stratocumulus clouds observed on 30 January. The former cloud layer, with a geometrical thickness of about 500 m (optical thickness of about 30), absorbed substantial (6%) and significant (21%) amounts of solar radiation in the visible and near-IR bands, respectively. For the latter mixed-phase cloud, on ah average over a long flight distance, the visible-band solar absorption was almost zero, while the near-IR-band absorption was about 24% for the cloud layer with a mean thickness of 1.3 km. The results indicate no sign of the so-called anomalous solar absorption for either cloud case. Through radiative transfer simulations for reasonable aerosol-cloud models, along with back trajectory analysis, the visible-band solar absorption by the aerosol-polluted cloud on 21 January was attributed to absorbing aerosols from continental East Asia. The simulation study also suggests that anthropogenic water-soluble aerosols, as well as soil-dust particles, may cause appreciable visible absorption by cloud particles, resulting in an enhanced solar heating in the boundary layer cloud. Copyright 2002 by the American Geophysical Union."
"7401984344;57203215073;","Solar influences on cosmic rays and cloud formation: A reassessment",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448947245&partnerID=40&md5=1758caaa60c82fffdcb1ca264476e33c","Svensmark and Friis-Christensen [1997] proposed a ""cosmic ray-cloud cover"" hypothesis that cosmic ray flux, modulated by solar activity, may modify global cloud cover and thus global surface temperature by increasing the number of ions in the atmosphere, leading to enhanced condensation of water vapor and cloud droplet formation. We evaluate this idea by extending their period of study and examining long-term surface-based cloud data (from national weather services and the Global Telecommunication System) as well as newer satellite data (International Satellite Cloud Climatology Project (ISCCP) D2, 1983-1993). No meaningful relationship is found between cosmic ray intensity and cloud cover over tropical and extratropical land areas back to the 1950s. The high cosmic ray-cloud cover correlation in the period 1983-1991 over the Atlantic Ocean, the only large ocean area over which the correlation is statistically significant, is greatly weakened when the extended satellite data set (1983-1993) is used. Cloud cover data from ship observations over the North Atlantic, where measurements are denser, did not show any relationship with solar activity over the period 1953-1995, though a large discrepancy exists between ISCCP D2 data and surface marine observations. Our analysis also suggests that there is not a solid relationship between cosmic ray flux and low cloudiness as proposed by Marsh and Svensmark [2000]. Copyright 2002 by the American Geophysical Union."
"8605057200;7202899330;","A new method for determining cloud transmittance and optical depth using the ARM micropulsed lidar",2002,"10.1175/1520-0426(2002)019<1073:ANMFDC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036638922&doi=10.1175%2f1520-0426%282002%29019%3c1073%3aANMFDC%3e2.0.CO%3b2&partnerID=40&md5=ddc8cd87f9ace9d59034295bc9627971","Cirrus clouds play an important role in the climate through their optical and microphysical properties. The problem with measuring the optical properties of these clouds can be partially addressed by using lidar systems. The calibration of backscatter lidar systems, in particular, typically relies on the known molecular (Rayleigh) backscatter, which is a function of temperature, pressure, and chemical composition of the air. This paper presents an improved method for determining the cloud transmittance, and thus optical depth, derived from backscatter lidar measurements. A system of equations is developed in terms of a proposed metric that is required to possess a minima, and has a unique solution for the gain, offset, and transmittance. The new method is tested on a synthetic case as well as using data from two different lidar systems that operate at two different wavelengths. The method is applied to lidar data collected by the lidar operating at the central Pacific island of Nauru under the auspices of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program."
"56250250300;12139310900;","A scheme for process-tagged SO4 and BC aerosols in NCAR CCM3: Validation and sensitivity to cloud processes",2002,"10.1029/2001JD000885","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448992308&doi=10.1029%2f2001JD000885&partnerID=40&md5=11aaa213a2c082440b05cc817bfa8403","A life cycle scheme for sulfate (SO4) and black carbon (BC) is implemented in an extended version of the National Center for Atmospheric Research (NCAR) Community Climate Model 3 (CCM3). The scheme includes emissions of dimethyl sulfide (DMS), SO2, and sulfate of natural and anthropogenic origins and emissions of BC from biomass burning and fossil fuel combustion. Chemistry and aerosol physics are parameterized based on prescribed oxidant levels and background aerosols of marine, continental, and polar origins. Aqueous chemistry depends on estimated exchange rate of cloudy and clear air. Particulate SO4 and BC are tagged by-production mechanisms for off-line reconstruction of aerosol optical and water activity properties. With emissions from International Panel on Climate Change (IPCC), calculations without feedback produce atmospheric turnover times (days) of 1.5 (SO2), 3.5 (SO4), and 4.7 (BC) for the year 2000 and 1.6 (SO2), 4.0 (SO4), and 4.7 (BC) for the year 2100 A2 emission scenario. The modeled SOx compounds compare within a factor 2 with observations at ground level in North America and Europe and for SO4 in the free troposphere. For BC, the ground-level concentrations are well within a factor 10 from observations over several regions. BC and SO4 are a factor 10 too low in Arctic winter, which can partly be linked to spurious low-level winter cloudiness. SO4 and BC are a factor 10 too high at ground-level low latitudes, and upper tropospheric SO2 is largely missing. These major model biases are caused by neglected transport and low scavenging efficiency in cumulus clouds. Cloud processes are discussed by sensitivity tests. SO4 and BC are found very sensitive to the vertical transport and scavenging in convective clouds. More research should aim at improved cloud parameterization schemes that address key processes associated with aerosols to reduce uncertainties associated with climate effects of anthropogenic aerosols. Copyright 2002 by the American Geophysical Union."
"7004539828;6603568514;","Influence of phytoplankton on the global radiation budget",2002,"10.1029/2001JD000562","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448952334&doi=10.1029%2f2001JD000562&partnerID=40&md5=f662bac6d2842bce12506a2a382580bf","[1] Oceanic phytoplankton may exert a warming influence on the planet by decreasing surface albedo. Compared with the case of pure seawater, the globally and annually averaged outgoing radiative flux is decreased by a probable value of 0.25 Wm-2. This value corresponds to about 20% of the combined radiative forcing by greenhouse gases and anthropogenic aerosols since preindustrial times, including indirect effects. The relative importance of phytoplankton is greater on regional and seasonal scales, with forcing values reaching -1.5 Wm-2 in coastal zones and high-latitude regions during summer. The annual amplitude of radiative forcing by phytoplankton is large in subpolar regions, owing to the conjugate action of cloud amount and biomass level. Spatial and temporal variability of the forcing is affected by phytoplankton type, some reflective species increasing the outgoing radiative flux. The effects of space- and time-varying phytoplankton on surface albedo should be taken into account explicitly in the numerical modeling of climate change. Copyright 2002 by the American Geophysical Union."
"7202570641;6603567450;","The potential influence of climate change on offshore primary production in Lake Michigan",2002,"10.1016/S0380-1330(02)70608-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036970889&doi=10.1016%2fS0380-1330%2802%2970608-4&partnerID=40&md5=971efbb714d2ea85ee36bd2d143011e8","This paper examines the potential influence of climate change on the primary productivity of Lake Michigan. Two general circulation models (GCMs) provided physical information on projected regional climate for the years 2030, 2050, and 2090. A 30-year record of meteorological data and limnological observations, from 1961 to through 1990, was used to define present, baseline conditions for the lake. GCM output was used to develop scenarios of future thermal characteristics, mixing patterns, and surface irradiance, which were then used to drive primary production calculations. Mean annual primary production for the base period was 116 g C/m2. Under base conditions thermal stratification of the lake occurred on 13 June and extended 135 days until 26 October. Conditions projected for 2090 showed the mean date of stratification beginning as early as 5 April and remaining for 225 days until 20 November. Estimated mean annual primary production under these conditions totaled 113 g C/m2, a decrease of 3% from the mean base value. Under the most extreme conditions of maximum projected cloud cover for 2090, primary production in that year could fall to 101 g C/m2, a decrease of 13% from the base mean, or down 22% from maximum base production calculated under minimum base cloud cover conditions. The projected decrease may be attributed to physical/chemical constraints imposed on spring primary production by altered climate conditions. Early stratification would shorten the period of winter-spring mixing, during which time nutrients from the sediment are transported to the productive euphotic zone. The spring bloom was projected to diminish if early stratification capped the nutrient supply, and increased cloud cover reduced light input for photosynthesis. To a lesser extent fall production could also be reduced by the extension of the stratified period. Altered physical/chemical conditions influenced by a changing climate will be an important factor to consider in assessing future water quality conditions, primary production and the food web dynamics of the Great Lakes."
"7501855361;16637291100;","Aggregate-area radiative flux biases",2002,"10.3189/172756402781817455","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036340362&doi=10.3189%2f172756402781817455&partnerID=40&md5=8d58174ab68e64335f1b819e5cd0c4d2","Most climate models treat surface and atmospheric properties as being horizontally homogeneous and compute surface radiative fluxes with average gridcell properties. In this study it is found that large biases can occur if sub-gridcell variability is ignored, where bias is defined as the difference between the average of fluxes computed at high resolution within a model cell and the flux computed with the average surface and cloud properties within the cell. Data from the Advanced Very High Resolution Radiometer for the year-long Surface Heat Budget of the Arctic Ocean (SHEBA) experiment are used to determine biases in aggregate-area fluxes. A simple regression approach to correct for biases that result from horizontal variability was found to reduce the average radiative flux bias to near zero. The correction can be easily implemented in numerical models."
"6701764148;7202162685;35576836000;7004353965;7102552750;7005311892;57213329429;7202087563;57218970790;7801620049;7005534492;7003455444;7007114588;56835353400;7006478660;6602254503;6505533774;7101693846;6701481405;7103106232;7003663305;6603746990;7006393267;55664095100;7003756536;6603885363;7101872548;6504491794;","Surface heat budget of the arctic ocean",2002,"10.1175/1520-0477(2002)083<0255:SHBOTA>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036225521&doi=10.1175%2f1520-0477%282002%29083%3c0255%3aSHBOTA%3e2.3.CO%3b2&partnerID=40&md5=eb63bb2c51e0cb30f2af834953d94673","The Surface Heat Budget of the Arctic Ocean (SHEBA) is a research program designed to document, understand, and predict the physical processes that determine the surface energy budget and the sea-ice mass balance in the Arctic. This article discusses the goals of the SHEBA II science program, field operations, and the resulting measurements. Some examples of datasets are shown for the full annual cycle as well as for one stormy rainy day in December. The issue of scaling up the ice camp measurements to represent conditions over the Arctic Basin is discussed, and the conditions of SHEBA year are examined with respect to recent arctic climate. Furthermore, the objectives of SHEBA phase III are briefly described."
"6602097544;6701378450;57196499374;","Black carbon radiative heating effects on cloud microphysics and implications for the aerosol indirect effect. 1. Extended Köhler theory",2002,"10.1029/2002JD002094","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751266317&doi=10.1029%2f2002JD002094&partnerID=40&md5=7cf0b63dac10dce70f952363751fca36","Black carbon (BC) aerosol absorbs sunlight that might have otherwise been reflected to space and changes the radiative heating of the atmosphere and surface. These effects may alter the dynamical and hydrological processes governing cloud formation. A new, microphysical, effect of BC on climate is identified here, in which solar heating within BC-containing cloud condensation nuclei (CCN) slows or prevents the activation of these CCN into cloud drops. Solar-heated BC-containing droplets are elevated in temperature by fractions of a degree above the ambient, thus raising the droplet vapor pressure and inhibiting activation of the most absorptive CCN. This paper develops the theory describing the alteration of the Köhler curve (i.e., the equilibrium vapor pressure over a droplet as a function of water uptake) as a function of CCN size and BC fraction. The effect is most significant in those CCN that contain volumes of BC larger than a 500 nm diameter sphere. For an aerosol population with 10% BC mass fraction per particle, solar heating can cause a 10% reduction in the CCN concentration at 0.01% critical supersaturation. On the other hand, the effect of heating by BC absorption on CCN activation above ∼0.1% critical supersaturation is negligible. Copyright 2002 by the American Geophysical Union."
"7006729638;","Economic impacts of climate variability in South Africa and development of resource prediction models",2002,"10.1175/1520-0450(2002)041<0046:EIOCVI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036333791&doi=10.1175%2f1520-0450%282002%29041%3c0046%3aEIOCVI%3e2.0.CO%3b2&partnerID=40&md5=1ceaa4aeee54c0ff7e0d7436ccfa5478","An analysis of food and water supplies and economic growth in South Africa leads to the realization that climate variability plays a major role. Summer rainfall in the period of 1980-99 is closely associated (variance = 48%) with year-to-year changes in the gross domestic product (GDP). Given the strong links between climate and resources, statistical models are formulated to predict maize yield, river flows, and GDP directly. The most influential predictor is cloud depth (outgoing longwave radiation) in the tropical Indian Ocean in the preceding spring (September-November). Reduced monsoon convection is related to enhanced rainfall over South Africa in the following summer and greater economic prosperity during the subsequent year. Methodologies are outlined and risk-reduction strategies are reviewed. It is estimated that over U.S.$1 billion could be saved annually through uptake of timely and reliable long-range forecasts."
"6603433259;56853406500;","Impact of land use/land cover change on regional hydrometeorology in Amazonia",2002,"10.1029/2000JD000266","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646518132&doi=10.1029%2f2000JD000266&partnerID=40&md5=127530219208c695e8e205e54c75ba0a","[1] A high-resolution mesoscale model was used to investigate the impact of deforestation in Amazonia. Coherent mesoscale circulations were triggered by the surface heterogeneity; synoptic flow did not eliminate the circulations but advected them away from the location where they were generated. This was substantiated by satellite-derived cloud images. These circulations affected the transport of moisture and heat at the synoptic scale and can affect climate. Adequate parameterizations for these processes should be included in GCMs tor more accurate climate simulations. Copyright 2002 by the American Geophysical Union."
"26643250500;57203053317;","A Parameterization of cirrus cloud formation: Homogeneous freezing including effects of aerosol size",2002,"10.1029/2001JD001429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448972755&doi=10.1029%2f2001JD001429&partnerID=40&md5=5890d3ddffb64c90887fea37ddc29023","In a previous study, we have derived an approximate, physically based parameterization of cirrus cloud formation by homogeneous freezing, applying to a wide class of supercooled aerosols in the upper troposphere and tropopause region. In this study, the parameterization scheme is extended to include the effects of aerosol size on the freezing process in adiabatically rising air parcels. Aerosol size effects become important when the timescale of the freezing event is fast compared to the timescale of depositional growth of the pristine ice particles. The generalized parameterization scheme is validated with parcel model simulations and can directly be applied in models that do not explicitly resolve the ice nucleation process, such as cloud-resolving models, weather forecast models, and climate models. The relationship between aerosol and ice crystal number concentrations in cirrus clouds formed by homogeneous freezing is discussed. This relationship is much weaker than in liquid water clouds. It is shown that even freezing of enhanced levels of sulfate aerosol originating from strong volcanic eruptions is unlikely to exert a sensible influence on cirrus formation. Copyright 2002 by the American Geophysical Union."
"55470017900;6602407753;35463545000;13403957300;7402934750;7005981420;35988494900;7201614869;","Full-time, eye-safe cloud and aerosol lidar observation at atmospheric radiation measurement program sites: Instruments and data processing",2002,"10.1175/1520-0426(2002)019<0431:FTESCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036259114&doi=10.1175%2f1520-0426%282002%29019%3c0431%3aFTESCA%3e2.0.CO%3b2&partnerID=40&md5=6d9a37c7a118aab3d8fc2c4db81f2b61","Atmospheric radiative forcing, surface radiation budget, and top-of-the-atmosphere radiance interpretation involve knowledge of the vertical height structure of overlying cloud and aerosol layers. During the last decade, the U.S. Department of Energy, through the Atmospheric Radiation Measurement (ARM) program, has constructed four long-term atmospheric observing sites in strategic climate regimes (north-central Oklahoma; Barrow, Alaska; and Nauru and Manus Islands in the tropical western Pacific). Micropulse lidar (MPL) systems provide continuous, autonomous observation of nearly all significant atmospheric clouds and aerosols at each of the central ARM facilities. These systems are compact, and transmitted pulses are eye safe. Eye safety is achieved by expanding relatively low-powered outgoing pulse energy through a shared, coaxial transmit/receive telescope. ARM MPL system specifications and specific unit optical designs are discussed. Data normalization and calibration techniques are presented. These techniques, in tandem, represent an operational value-added processing package used to produce normalized data products for ARM cloud and aerosol research."
"57206128696;6603646841;7003473171;","Climatic impacts on the runoff generation processes in British Columbia, Canada",2002,"10.5194/hess-6-211-2002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036300061&doi=10.5194%2fhess-6-211-2002&partnerID=40&md5=12c7048bf886072bfff661edb8d9c4a6","The potential impact of future climate change on runoff generation processes in two southern British Columbia catchments was explored using the Canadian Centre for Climate Modelling Analysis General Circulation Model (CGCMa1) to estimate future changes in precipitation, temperature and cloud cover while the U.B.C. Watershed Model was used to simulate discharges and quantify the separate runoff components, i.e rainfall, snowmelt, glacier melt and groundwater. Changes, not only in precipitation and temperature but also in the spatial distribution of precipitation with elevation, cloud cover, glacier extension, altitude distribution of vegetation biomass production and plant physiology were considered. The future climate of the catchments would be wetter and warmer than the present. In the maritime rain-fed catchment of the Upper Campbell, runoff from rainfall is the most significant source of flow for present and future climatic conditions in the autumn and winter whereas runoff from groundwater generates the flow in spring and summer, especially for the future climate scenario. The total runoff, under the future climatic conditions, would increase in the autumn and winter and decrease in spring and summer. In contrast, in the interior snow-covered Illecillewaet catchment, groundwater is the most significant runoff generation mechanism in the autumn and winter although, at present, significant flow is generated from snowmelt in spring and from glacier runoff in summer. In the future scenario, the contribution to flow from snowmelt would increase in winter and diminish in spring while the runoff from the glacier would remain unchanged; groundwater would then become the most significant source of runoff, which would peak earlier in the season."
"7202899330;7004485096;6603079470;35494005000;7005171879;7410041005;7007114756;7006146719;7004540083;7005890897;55476786400;7202857052;7202060229;8605057200;","The cloudsat mission and the A-Train: A new dimension of space-based observations of clouds and precipitation",2002,"10.1175/bams-83-12-1771","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036994078&doi=10.1175%2fbams-83-12-1771&partnerID=40&md5=a1dc76cc6cb6210b225fc0c591f22eec","CloudSat is a satellite experiment designed to measure the vertical structure of clouds from space. The expected launch of CloudSat is planned for 2004, and once launched, CloudSat will orbit in formation as part of a constellation of satellites (the A-Train) that includes NASA's Aqua and Aura satellites, a NASA-CNES lidar satellite (CALIPSO), and a CNES satellite carrying a polarimeter (PARASOL). A unique feature that CloudSat brings to this constellation is the ability to fly a precise orbit enabling the fields of view of the CloudSat radar to be overlapped with the CALIPSO lidar footprint and the other measurements of the constellation. The precision and near simultaneity of this overlap creates a unique multisatellite observing system for studying the atmospheric processes essential to the hydrological cycle. The vertical profiles of cloud properties provided by CloudSat on the global scale fill a critical gap in the investigation of feedback mechanisms linking clouds to climate. Measuring these profiles requires a combination of active and passive instruments, and this will be achieved by combining the radar data of CloudSat with data from other active and passive sensors of the constellation. This paper describes the underpinning science and general overview of the mission, provides some idea of the expected products and anticipated application of these products, and the potential capability of the A-Train for cloud observations. Notably, the CloudSat mission is expected to stimulate new areas of research on clouds. The mission also provides an important opportunity, to demonstrate active sensor technology for future scientific and tactical applications. The CloudSat mission is a partnership between NASA's JPL, the Canadian Space Agency, Colorado State University, the U.S. Air Force, and the U.S. Department of Energy."
"7006920633;","Four billion years of the carbon cycle what's in it for us?",2002,"10.1260/0958305021501137","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036190108&doi=10.1260%2f0958305021501137&partnerID=40&md5=53edf44cd8889cdc20273c83743f0e9e","Carbon dioxide, generally believed to be the most important greenhouse gas and climate modifier, is today the centrepiece of heated political and scientific debate. In its most polarised form, one side maintains that CO2 is the principal ""driver"" of climate and the sequence of events is ""higher CO2 equals global warming equals climate change equals disaster"". Based on this scenario, the burning of fossil fuels and deforestation will inexorably lead to global warming, with the latest IPCC models projecting an average 1.5 to 5.5°C temperature rise by the year 2100. Environmental Armageddon is an inevitable consequence of the above equation. The opposing view claims that the role of anthropogenic CO2 on climate has not been proved, and that there is therefore no need for the large expenditures necessitated by the emission-curtailment quotas, such as those mandated by the Kyoto protocol. As is usually the case with contentious matters, the reality is likely somewhere in between, and the polarisation arises mostly from two issues: (1) poor understanding of past variations in the carbon cycle and climate that must be taken into account as a baseline for any superimposed human impact, and (2) the uncertainties inherent in the climate models. This essay will deal mostly with the first subject, the carbon cycle, from the perspective of a geologist, contemplating it at times scales ranging from billions of years to the human life span. This perspective is essential, because events on progressively shorter time scales are embedded in, and constrained by, the evolution of the background on longer time scales. In terms of the second issue, the uncertainties inherent in the climate models, the admirable progress achieved by climate modelling must be acknowledged, but many serious pitfalls, such as the role of clouds, or the couplings to the oceanic and particularly the terrestrial biosphere (land plants), remain to be resolved. Considering that theoretical cooling by the clouds alone may potentially exceed, by up to 7. 5 times, the warming impact of the greenhouse gases (radiative forcing of - 18 vs. + 2.45 W m-2), such concerns should be given due consideration and resolved prior to any definitive claims based on the climate scenarios. Not being a modeller, on the issue of modelling I will restrict myself solely to the role of land plants in the carbon cycle because of their potential impact on the ""CO2 sinks"" debate, which was the cause of failure of the Hague summit."
"7501488862;7006738324;","Development of a nonlinear statistical method for estimating the downward longwave radiation at the surface from satellite observations",2002,"10.1175/1520-0426(2002)019<1500:DOANSM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036810887&doi=10.1175%2f1520-0426%282002%29019%3c1500%3aDOANSM%3e2.0.CO%3b2&partnerID=40&md5=b0e9c3ce6a3bb2cfaa3cb53c07f526ad","This paper develops a nonlinear statistical method that uses satellite radiance observations directly to estimate the downward longwave radiation (DLR) at the earth's surface, a necessary component of the surface energy budget. The proposed technique has rms regression errors of about 9 W m-2 for clear-sky conditions, and about 4 to 8 W m-2 for overcast conditions, depending on the cloud levels. It is shown that this technique can produce unbiased estimates over a large range of meteorological conditions, which is crucial for climate studies. Sensitivity studies show that the DLR is most sensitive to errors in the cloud amount on average. Overall, the combined errors for an instantaneous DLR estimate, excluding the effects of the surface pressure errors, range from about 7 to 12 W m-2 when there is a ±10% uncertainty in cloud amount and a ±100 hPa uncertainty in cloud-base pressure. When the cloud amount uncertainty rises to 30%, the combined DLR error ranges from about 10 to 25 W m-2. This clear-sky DLR estimation technique was validated preliminarily by using simulated radiation data. The DLR differences between estimated and calculated values have a standard deviation of about 9 W m-2 and are unbiased in most conditions. The validity of the DLR estimation technique has been demonstrated: however, validation for cloudy conditions, comparison with surface observations, and improvements related to surface pressure dependence and skin temperature discontinuity are left for future study."
"7201496259;7102604282;7007020226;7201699997;7101909186;25723426400;","Cloud susceptibility and the first aerosol indirect forcing: Sensitivity to black carbon and aerosol concentrations",2002,"10.1029/2000JD000215","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448977286&doi=10.1029%2f2000JD000215&partnerID=40&md5=6adb3c94dd662000fbafd55d2ac774e2","Present-day global anthropogenic emissions contribute more than half of the mass in submicron particles primarily due to sulfate and carbonaceous aerosol components derived from fossil fuel combustion and biomass burning. These anthropogenic aerosols increase cloud drop number concentration and cloud albedo. Here, we use an improved version of the fully coupled climate/chemistry models to investigate cloud susceptibility and the first indirect effect of anthropogenic aerosols (the Twomey effect). We examine the correspondence between the model simulation of cloud susceptibility and that inferred from satellite measurements to test whether our simulated aerosol concentrations and aerosol/cloud interactions give a faithful representation of these features. This comparison provides an overall measure of the adequacy of cloud cover and drop concentrations. We also address the impact of black carbon absorption in clouds on the first indirect forcing and examine the sensitivity of the forcing to different representations of natural aerosols. We find that including this absorption does not change the global forcing by more than 0.07 W m-2, but that locally it could decrease the forcing by as much as 0.7 W m-2 in regions where black carbon emissions are pronounced. Because of the nonlinear relationship between cloud drop number and aerosol number concentrations, the total forcing does not equal the sum of the forcing from each individual source. Our estimated total first indirect forcing is -1.85 W m-2, with -0.30 W m-2 associated with anthropogenic sulfate, -1.16 W m-2 associated with carbonaceous aerosols from biomass burning, and -0.52 W m-2 associated with carbonaceous aerosols from fossil fuel combustion. Estimates of forcing by sulfate and total carbonaceous aerosols increase to -0.31 and -1.67 W m-2, respectively, if natural emissions of organic aerosols are only 8.4 tg yr-1, but decrease to -0.26 and -1.27 W m-2 if they are as large as 42 Tg yr-1. Even larger estimates of forcing are derived if dust and sea-salt emissions are not included. The effect of aerosol abundance on cloud life cycle may be important but is not treated in this Study. Copyright 2002 by the American Geophysical Union."
"57211106013;57196499374;","Predicting global aerosol size distributions in general circulation models",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-32144459823&partnerID=40&md5=ad8f25f9a60bd58f6d52f76020788e64","To better represent the indirect effect of aerosols on climate, a size-resolved simulation of aerosol microphysics, size distributions, number and mass concentrations has been incorporated into the GISS general circulation model (GCM). The TwO-Moment Aerosol Sectional (TOMAS) microphysics model used here conserves aerosol number as well as mass. It has high size resolution, 30 bins between 0.01 and 10 μm diameter. As a first application, a size-resolved simulation of sulfate has been performed. The model reproduces important features of the atmospheric aerosol such as number concentrations that increase with altitude and land-sea contrasts in aerosol number concentrations and size distributions. Comparisons with observations show that simulated size distributions are realistic and condensation nuclei (CN) concentrations agree with observations within about 25%. Predicted cloud condensation nuclei (CCN) concentrations are also in reasonable agreement with observations, although there are locations for which agreement would be improved by including other aerosol components such as sea salt and carbonaceous aerosols. Sensitivity scenarios show that uncertainties in nucleation and primary emissions from fossil fuels can have significant effects on predictions of CN and CCN concentrations. Copyright 2002 by the American Geophysical Union."
"7005682116;7005071210;","Daily air temperature and pressure series for Uppsala (1722-1998)",2002,"10.1023/A:1014983229213","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036100574&doi=10.1023%2fA%3a1014983229213&partnerID=40&md5=ccff806cbf87ac63ea042578ad3e38ff","Daily meteorological observations have been made in Uppsala, Sweden, since 1722, and complete series of air temperature and sea level air pressure have been reconstructed and homogenised for the period 1722-1998. The reconstruction work was based on the hand written registers and printed monthly bulletins before 1985, after which data was directly stored on computers. Methods to determine daily average temperatures from the typically available 2-3 observations per day were developed. These methods take into account observation times and cloud amount. Pressure reductions back to 1840 involved only routine calculations, while earlier pressure data needed major homogenisations. All data were searched for errors by comparisons with previously determined monthly averages and by different plotting techniques, mainly comparing with independently reconstructed data from Stockholm, 65 km south of Uppsala. This comparison also shows that the quality of the data is generally good, although the reliability is lower before the mid-19th century. Results are given illustrating changes in the daily average temperature and pressure climate on a 200-250 year time scale."
"8517503000;","Application of factor analysis for quantification of climate-forming processes in the eastern part of the Baltic Sea region",2002,"10.3354/cr020135","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036323506&doi=10.3354%2fcr020135&partnerID=40&md5=9f853bde6ff3227ac4f0066a78de5996","Factor analysis (FA) is applied to identify climate-forming factors and quantitatively evaluate their importance in the eastern part of the Baltic Sea region. Monthly data from 7 meteorological stations are used: average maximum and average minimum of air temperature (T1 and T2), atmospheric pressure (P), wind speed at a hieght of 10 m (v), monthly precipitation (Q), duration of sunshine (S) and partial pressure of water vapour (e). FA reveals that the variables form 2 main groups (meteorological complexes): a hygrothermal complex-T1, T2 and e-and a baric-radiational complex-P, Q and S. Both meteorological complexes exist almost independently of each other (in cold seasons in particular), i.e. it is possible to distinguish the 2 most important types of climate-forming processes in the eastern part of the Baltic Sea region. One of them is advection related to the input of various air masses whose features are best reflected by air temperature and humidity. The other process mostly takes place within 1 pressure system (cyclone or anticyclone): air mass transformation, vertical mixing, formation of clouds and related precipitation and input of solar radiation."
"7003478309;7005399437;7005793702;55725404100;35464731600;35468686100;55947099700;7004299722;","Variability of absorption and optical properties of key aerosol types observed in worldwide locations",2002,"10.1175/1520-0469(2002)059<0590:voaaop>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051896810&doi=10.1175%2f1520-0469%282002%29059%3c0590%3avoaaop%3e2.0.co%3b2&partnerID=40&md5=516305ef076482aeb8d1ff76a2cf66ac","Aerosol radiative forcing is a critical, though variable and uncertain, component of the global climate. Yet climate models rely on sparse information of the aerosol optical properties. In situ measurements, though important in many respects, seldom provide measurements of the undisturbed aerosol in the entire atmospheric column. Here, 8 yr of worldwide distributed data from the AERONET network of ground-based radiometers were used to remotely sense the aerosol absorption and other optical properties in several key locations. Established procedures for maintaining and calibrating the global network of radiometers, cloud screening, and inversion techniques allow for a consistent retrieval of the optical properties of aerosol in locations with varying emission sources and conditions. The multiyear, multi-instrument observations show robust differentiation in both the magnitude and spectral dependence of the absorption - a property driving aerosol climate forcing, for desert dust, biomass burning, urban-industrial, and marine aerosols. Moreover, significant variability of the absorption for the same aerosol type appearing due to different meteorological and source characteristics as well as different emission characteristics are observed. It is expected that this aerosol characterization will help refine aerosol optical models and reduce uncertainties in satelite observations of the global aerosol and in modeling aerosol impacts on climate."
"7101828023;","Mixing patterns and plankton biomass of the St. Lawrence Great Lakes under climate change scenarios",2002,"10.1016/S0380-1330(02)70607-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036965545&doi=10.1016%2fS0380-1330%2802%2970607-2&partnerID=40&md5=0b5485d0ff60ac9b17ccb251410dd7ee","This study is part of an assessment of potential effects of climate change on the St. Lawrence Great Lakes. Its purpose is to investigate potential future lake mixing patterns and primary production. Nested physical and biological models were applied to seasonal mixed layer depth, heat content, primary productivity, and to algal biomass measured as particulate chlorophyll. Two independent second generation General Circulation Models provided scenarios for future conditions of cloud cover, air temperature, humidity, and winds. The climate variables were used to force heat balance and surface mixed layer models for Lakes Superior, Michigan, Huron, Erie, and Ontario. Physical models of heat balance and mixed layer dynamics were coupled with a model of primary biological production and growth of phytoplankton. Simulated climate conditions were for time periods centered at 1975, 2030, 2050, and 2090. Climate projections from both GCMs lead to elevated mixed layer and bottom temperatures in all five lakes by as much as 5°C during this century. Both GCMs point to longer duration of thermal stratification in the five lakes, stronger stability of stratification, and deeper daily mixing depths during peak thermal stratification. For Lake Erie, no striking differences in algal biomass are likely according to climate projections of either model, but for the other lakes, either the duration of nutrient limitation of algal growth is projected to increase, or light limitation caused by deeper mixing is projected to limit the development of algal biomass."
"7402826517;23012561700;7404334532;","General circulation model simulations of recent cooling in the east-central United States",2002,"10.1029/2001JD001577","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448973846&doi=10.1029%2f2001JD001577&partnerID=40&md5=9ca10dd86f06d7832cb91b7e6daedd8f","In ensembles of retrospective general circulation model (GCM) simulations, surface temperatures in the east-central United States cool between 1951 and 1997. This cooling, which is broadly consistent with observed surface temperatures, is present in GCM experiments driven by observed time varying sea-surface temperatures (SSTs) in the tropical Pacific, whether or not increasing greenhouse gases and other time varying climate forcings are included. Here we focus on ensembles with fixed radiative forcing and with observed varying SST in different regions. In these experiments the trend and variability in east-central U.S. surface temperatures are tied to tropical Pacific SSTs. Warm tropical Pacific SSTs cool U.S. temperatures by diminishing solar heating through an increase in cloud cover. These associations are embedded within a year-round response to warm tropical Pacific SST that features tropospheric warming throughout the tropics and regions of tropospheric cooling in midlatitudes. Precipitable water vapor over the Gulf of Mexico and the Caribbean and the tropospheric thermal gradient across the Gulf Coast of the United States increase when the tropical Pacific is warm. In observations, recent warming in the tropical Pacific is also associated with increased precipitable water over the southeast United States. The observed cooling in the east-central United States, relative to the rest of the globe, is accompanied by increased cloud cover, though year-to-year variations in cloud cover, U.S. surface temperatures, and tropical Pacific SST are less tightly coupled in observations than in the GCM. Copyright 2002 by the American Geophysical Union."
"57206456336;55168738600;7006344866;","Budget and export of anthropogenic SOx from East Asia during continental outflow conditions",2002,"10.1029/2001JD000769","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346682006&doi=10.1029%2f2001JD000769&partnerID=40&md5=3609549c6fd47c0a46a402512e231fae","We examine the budget and export of anthropogenic SOx (SO 2 and sulfate aerosol) emitted from East Asia during the late winter/early spring when continental outflow conditions dominate. Our study is based on simulations using a modified version of the China-MAP coupled regional climate/chemical transport model of Qian and Giorgi [1999]. The modification involves the addition of algorithms to treat the vertical transport and removal of SOx by convective clouds. Model-calculated anthropogenic SO 2 concentrations peaked at values greater than 20 ppbv at the surface in the urban source regions of China and Korea, but averaged only about 5 pbbv in the rural areas. Midtropospheric SO2 concentrations were more than an order of magnitude less, with peak values of around 0.1-0.15 ppbv overlying the urban source regions. The model-calculated sulfate aerosol distribution is more disperse, with peak surface concentrations of 5-10 ppbv in urban source regions, and concentrations of about 3 ppbv or less in rural areas and 1 ppbv or less in the midtroposphere. The model-calculated SOx concentrations are generally within a factor of 2 of the relevant observed concentrations at nonurban sites. The calculations indicate that during the late winter/early spring period, about 50% of the anthropogenic SOx emitted over East Asia is removed from the continental source regions. Roughly 30% is wet and dry deposited onto the neighboring oceans, and the remaining 20% is exported out of the model domain. The vast majority of the exported SOx is in the form of sulfate aerosol and is transported into the midtroposphere overlying the North Pacific Ocean. The rate of SOx export, about 0.2 Tg S per month, is significant when compared to natural S sources to the North Pacific Ocean, suggesting that the export of anthropogenic SOx from East Asia is perturbing sulfate aerosol concentrations over the North Pacific Ocean during the late winter and early spring. On an intraregional basis we find that China is the largest contributor to the emission and export of SOx from East Asia. However, all the nations/continental subregions of East Asia appear to be net exporters of SOx, even those downwind of China. Copyright 2002 by the American Geophysical Union."
"7501381728;35448188800;57203052274;7005543472;7003386805;6505876262;7103056277;7202628826;57206038917;7102447698;7405857939;6601992794;6701594686;","An improved retrieval of tropospheric nitrogen dioxide from GOME",2002,"10.1029/2001JD001027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646516193&doi=10.1029%2f2001JD001027&partnerID=40&md5=24a221484753e6b50c9baacd977d3ade","We present a retrieval of tropospheric nitrogen dioxide (NO<inf>2</inf>) columns from the Global Ozone Monitoring Experiment (GOME) satellite instrument that improves in several ways over previous retrievals, especially in the accounting of Rayleigh and cloud scattering. Slant columns, which are directly fitted without low-pass filtering or spectral smoothing, are corrected for an artificial offset likely induced by spectral structure on the diffuser plate of the GOME instrument. The stratospheric column is determined from NO<inf>2</inf> columns over the remote Pacific Ocean to minimize contamination from tropospheric NO<inf>2</inf>. The air mass factor (AMF) used to convert slant columns to vertical columns is calculated from the integral of the relative vertical NO<inf>2</inf> distribution from a global 3-D model of tropospheric chemistry driven by assimilated meteorological data (Global Earth Observing System (GEOS)-CHEM), weighted by altitude-dependent scattering weights computed with a radiative transfer model (Linearized Discrete Ordinate Radiative Transfer), using local surface albedos determined from GOME observations at NO<inf>2</inf> wavelengths. The AMF calculation accounts for cloud scattering using cloud fraction, cloud top pressure, and cloud optical thickness from a cloud retrieval algorithm (GOME Cloud Retrieval Algorithm). Over continental regions with high surface emissions, clouds decrease the AMF by 20-30% relative to clear sky. GOME is almost twice as sensitive to tropospheric NO<inf>2</inf> columns over ocean than over land. Comparison of the retrieved tropospheric NO<inf>2</inf> columns for July 1996 with GEOS-CHEM values tests both the retrieval and the nitrogen oxide radical (NO<inf>x</inf>) emissions inventories used in GEOS-CHEM. Retrieved tropospheric NO<inf>2</inf> columns over the United States, where NO<inf>x</inf> emissions are particularly well known, are within 18% of GEOS-CHEM columns and are strongly spatially correlated (r = 0.78, n = 288, p < 0.005). Retrieved columns show more NO<inf>2</inf> than GEOS-CHEM columns over the Transvaal region of South Africa and industrial regions of the northeast United States and Europe. They are lower over Houston, India, eastern Asia, and the biomass burning region of central Africa, possibly because of biases from absorbing aerosols. Copyright 2002 by the American Geophysical Union."
"7003935733;7101831681;6602153074;7202163945;57206422780;","Applications of satellite remote sensing in numerical weather and climate prediction",2002,"10.1016/S0273-1177(02)80298-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036875865&doi=10.1016%2fS0273-1177%2802%2980298-8&partnerID=40&md5=a5dbfb68b2f867d800f83b0bb6b8df60","The year 2000 marks the 40 th anniversary of the launch of the first weather satellite. The images of cloud systems from the early satellites enabled forecasters to locate and monitor the movements of storms. Today's satellites provide a wealth of quantitative information about the constantly changing state of the Earth's atmosphere, ocean, and land surface. Significant strides are being made by operational centers around the world to effectively use these remotely-sensed observations in forecast models. The satellite measurements are used to initialize, provide boundary conditions for, and verify predictions ofmodels. As an example of the state of the art, this paper reviews how satellite observations are used in the numerical weather and climate prediction models of the U.S. National Weather Service. The National Weather Service, National Centers for Environmental Prediction (NCEP), Environmental Modeling Center (EMC) develops regional and global weather prediction models, coupled ocean-atmosphere models for seasonal to interannual climate predictions, and a coastal ocean forecast model. A three dimensional variational data assimilation system is used to specify the initial conditions for the forecast models. Data from the following satellite instruments are currently used in one or more ofthese models: High Resolution Infrared Sounder (HIRS), Microwave Sounding Unit (MSU), Advanced Microwave Sounding Unit-A (AMSU-A), Geostationary Operational Environmental Satellites (GOES) sounder, GOES, METEOSAT, and Geostationary Meteorology Satellite (GMS) imagers, Advanced Very High Resolution Radiometer (AVHRR), Special Sensor Microwave/Imager (SSM/I), ESA Remote-sensing Satellite-2 (ERS-2) scatterometer, Solar Backscatter Ultraviolet Spectrometer/2 (SBUV/2), and Oceanic Topography Experiment (TOPEX) and ERS-2 altimeters. Published by Elsevier Science Ltd on behalf of COSPAR."
"6603764342;7103033688;7003481980;","The North Atlantic Oscillation influence on Europe: Climate impacts and associated physical mechanisms",2002,"10.3354/cr020009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036320329&doi=10.3354%2fcr020009&partnerID=40&md5=5ff49471f7f77181650af5a0dd582500","A multivariable analysis of the influence of the North Atlantic Oscillation (NAO) on the climate of the North Atlantic and European sectors is presented using the 40 yr (1958-1997) consistent data set from NCEP. Using high and low NAO index composites, anomaly fields of climate variables are then interpreted based on physical mechanisms associated with the anomalous mean flow (characterised by the surface wind field) and the anomalous eddy activity (characterised by the surface vorticity and the 500 hPa storm track fields). It is shown that NAO-related temperature patterns are mainly controlled by the advection of heat by the anomalous mean flow. However, large asymmetries between minimum and maximum temperatures, and more significantly, between positive and negative phases of NAO imply the importance of a different mechanism, namely, the modulation of short wave and long wave radiation by cloud cover variations associated with the NAO. Furthermore, NAO influence on 2 different precipitation-related variables-precipitation rate and precipitable water-displays different patterns. Precipitable water is shown to be strongly related to the corresponding anomaly fields of temperature while precipitation rate appears to be controlled by the surface vorticity field and associated strength of the tropospheric synoptic activity."
"36538539800;7006270084;7003666669;6602973136;","Impact of aerosol size representation on modeling aerosol-cloud interactions",2002,"10.1029/2001JD001549","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448987568&doi=10.1029%2f2001JD001549&partnerID=40&md5=a0fb9c063d750b54dc8d4ed9fdba6189","[1] We use a one-dimensional version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the second Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high-resolution 108-section approach. The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7 to 161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for nonlognormal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution). Copyright 2002 by the American Geophysical Union."
"36538539800;7006270084;7003666669;6602973136;","Impact of aerosol size representation on modeling aerosol-cloud interactions",2002,"10.1109/AERO.2002.1036876","https://www.scopus.com/inward/record.uri?eid=2-s2.0-16444385482&doi=10.1109%2fAERO.2002.1036876&partnerID=40&md5=ebc8abfe06589d9bbeebd3bd2268d2d5","We use a one-dimensional version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the second Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high-resolution 108-section approach. The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7 to 161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for nonlognormal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO<inf>2</inf> concentrations (i.e., greater modification of the initial aerosol distribution). Copyright 2002 by the American Geophysical Union."
"7006861646;6701633912;35729333400;57196396429;","A multisatellite analysis of deep convection and its moist environment over the Indian Ocean during the winter monsoon",2002,"10.1029/2000JD000040","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0043070168&doi=10.1029%2f2000JD000040&partnerID=40&md5=6073602f7f44933993c195e135a1785a","The aim of this paper is to characterize the deep convective systems over the Indian Ocean during Indian Ocean Experiment (INDOEX) and their relationship to cloudiness and to the Upper Tropospheric Humidity (UTH) of their environment together with the relevant longwave radiation fields. Multisatellite analyses are performed (Meteosat, Scanner for Radiation Budget (ScaRaB), and Special Sensor Microwave Imager (SSM/I)) to measure these environmental parameters. The use of Meteosat water vapor (WV) channel appears very efficient not only for estimating UTH but also for separating high level cloudiness, including thin cirrus, from clear sky and low clouds. The Meteosat infrared (IR) and WV channels are also used for correlating Meteosat and ScaRaB measurements, allowing to retrieve continuously the longwave radiative flux. The longwave flux is used to compute the cloud radiative forcing as well as the clear-sky greenhouse effect. Spatial relationships between upper level cloudiness and UTH are established. A strong positive linear relationship is found suggesting a local moistening of the upper troposphere by convection. The temporal analysis reveals that during the active phase of the intraseasonal oscillation, the longwave cloud radiative forcing reaches a mean value up to 40 W m-2 over a large region in the open ocean, while the average clear-sky greenhouse effect is in excess of 180 W m-2. These radiative parameters are strongly correlated with the upper level cloudiness and upper level moisture, respectively. The temporal variability of UTH explains up to 80% of the greenhouse effect variability. The structure of the convective cloud systems is then studied. The observed population of systems spans a wide spectrum of area from 100 to 1,000,000 km2. The contribution to the high level cloudiness of the systems with a strong vertical development is dominant. These systems, with at least one convective cell reaching the highest levels (below 210 K), present indices of overshooting tops and are the most horizontally extended. The largest system exhibits an average longwave radiative forcing of around 100 W m-2. Their contribution to the cloud forcing over the Indian Ocean is overwhelming. The spatial and temporal variability of the systems is finally related to the UTH and to the clear-sky greenhouse effect. Strong correlations are found indicating that these organized convective systems at mesoscale play a leading role in the Indian Ocean climate. The analysis suggests that deeper convection is associated with larger cloud desks with larger cloud radiative forcing. It is also associated with a moister upper troposphere and a larger clear-sky greenhouse effect. These two effects would provide a positive feedback on the surface conditions. Copyright 2002 by the American Geophysical Union."
"7101947667;7005984802;7006483900;16402575500;","Characteristics of Arctic polar stratospheric clouds in the winter of 1996/1997 inferred from ILAS measurements",2002,"10.1029/2001JD000595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0011061285&doi=10.1029%2f2001JD000595&partnerID=40&md5=309ec9febacbeabb0255434f16c317c4","The Improved Limb Atmospheric Spectrometer (ILAS) captured many polar stratospheric cloud (PSC) events in the Northern Hemisphere during the winter and early spring of 1997. Simultaneous measurements of nitric acid and aerosols by ILAS made it possible to infer PSC composition. The aerosol extinction coefficient and nitric acid data were compared with the theoretically predicted values for supercooled ternary solution (STS), nitric acid dihydrate (NAD), and nitric acid trihydrate (NAT) at thermodynamic equilibrium to classify PSC types. The observations showed that in 1997, both nitric-acid-containing solid and liquid PSCs formed over the Arctic during winter and early spring, until mid-March. The STS PSCs were observed early in the PSC season, in mid-January. Most of the PSCs observed late in the PSC season had features of nitric-acid-containing hydrates. An intensive analysis of the temperature histories suggested that most of the STS events observed in January had experienced the thermal conditions necessary for the formation of liquid PSCs. The nitric-acid-containing hydrates observed in March seemed not to have been influenced by any mountain-induced lee waves. The process of nitric-acid-containing hydrate formation based on synoptic scale temperature change is discussed. Copyright 2002 by the American Geophysical Union."
"7102290666;6506966551;7005920767;7202429440;7102842013;55947099700;","Aerosol optical depths and direct radiative forcing for INDOEX derived from AVHRR: Theory",2002,"10.1029/2000JD000182","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0012549890&doi=10.1029%2f2000JD000182&partnerID=40&md5=2151edb18e6e1e2f6dc7d3e5eadd8545","A scheme is presented for retrieving aerosol properties for ocean regions from reflected sunlight at both the visible and near infrared wavelengths measured by the NOAA advanced very high resolution radiometer (AVHRR). For the Indian Ocean Experiment (INDOEX), aerosols were presumed to be a mixture of a continental haze that had small particles, contained soot, and absorbed sunlight, and a marine haze that had large particles and absorbed practically no sunlight. Because of the difference in particle sizes, the two aerosols reflect sunlight differently at visible and near infrared wavelengths. Reflectances at visible and near infrared wavelengths were thus used to determine mixing fractions for the continental and marine aerosols and the optical depth of the aerosol mixture. The fractions and optical depths along with the optical properties of the aerosols were then used in radiative transfer calculations to estimate the diurnally averaged top of the atmosphere and surface aerosol direct radiative forcing for ocean regions. Comparison of retrieved optical depths at visible and near infrared wavelengths with surface measurements revealed that several different retrieval schemes employing a variety of aerosol types provided comparable levels of agreement, but none of the aerosol models or retrieval schemes produced ratios of the near infrared to visible optical depths that agreed with the ratios obtained with the surface measurements. In estimating the top of the atmosphere radiative forcing, errors in the retrieved optical depths were in some cases found to be partially compensated by the effect of the aerosol on the radiative flux. For example, different aerosol models led to retrieved optical depths that differed by as much as 60%, but the top of the atmosphere forcing obtained with the models differed by less than 35% for cloud-free conditions. When aerosols absorb sunlight, there is no comparable compensation for the surface forcing. Cloud conditions contribute sizable uncertainties to estimates of the aerosol direct radiative forcing. For INDOEX, estimates of the aerosol direct radiative forcing for average cloud conditions were obtained by (1) setting the forcing to zero for all 1̈ × 1̈ latitude-longitude boxes that contained any amount of upper-level cloud; (2) ascribing to regions with upper-level clouds the radiative forcing obtained for regions having only low-level clouds and, (3) setting the forcing to zero for all regions containing upper-level clouds and all portions of regions overcast by low-level clouds. Relative differences in the extreme values for the top of the atmosphere aerosol direct radiative forcing were less than 50%, but for the surface, the relative differences of the extreme values reached 70%. Copyright 2002 by the American Geophysical Union."
"7004537777;24440347100;7406740683;7405667997;","Stable isotope composition of waters in the Great Basin, United States 1. Air-mass trajectories",2002,"10.1029/2001JD000565","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448992639&doi=10.1029%2f2001JD000565&partnerID=40&md5=c0a3b6ae6b65b401d2dbeeed0bf90184","Isentropic trajectories, calculated using the NOAA/Climate Monitoring and Diagnostics Laboratory's isentropic transport model, were used to determine air-parcel origins and the influence of air mass trajectories on the isotopic composition of precipitation events that occurred between October 1991 and September 1993 at Cedar City, Utah, and Winnemucca, Nevada. Examination of trajectories that trace the position of air parcels backward in time for 10 days indicated five distinct regions of water vapor origin: (1) Gulf of Alaska and North Pacific, (2) central Pacific, (3) tropical Pacific, (4) Gulf of Mexico, and (5) continental land mass. Deuterium (δD) and oxygen-18 (δ18O) analyses were made of precipitation representing 99% of all Cedar City events. Similar analyses were made on precipitation representing 66% of the precipitation falling at Winnemucca during the same period. The average isotopic composition of precipitation derived from each water vapor source was determined. More than half of the precipitation that fell at both sites during the study period originated in the tropical Pacific and traveled northeast to the Great Basin; only a small proportion traversed the Sierra Nevada. The isotopic composition of precipitation is determined by air-mass origin and its track to the collection station, mechanism of droplet formation, reequilibration within clouds, and evaporation during its passage from cloud to ground. The Rayleigh distillation model can explain the changes in isotopic composition of precipitation as an air mass is cooled pseudo-adiabatically during uplift. However, the complicated processes that take place in the rapidly convecting environment of cumulonimbus and other clouds that are common in the Great Basin, especially in summer, require modification of this model because raindrops that form in the lower portion of those clouds undergo isotopic change as they are elevated to upper levels of the clouds from where they eventually drop to the ground."
"56520921400;7006705919;7102645933;8661887700;7005513582;57196905116;6603400519;","Simulation of aerosol distributions and radiative forcing for INDOEX: Regional climate impacts",2002,"10.1029/2000JD000032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751306192&doi=10.1029%2f2000JD000032&partnerID=40&md5=a4b2cfe1b13760c519fca8cb8785f7e6","The direct radiative forcing by aerosols over the Indian Ocean region is simulated for the Indian Ocean Experiment (INDOEX) Intensive Field Phase during Spring 1999. The forcing is calculated for the top-of-atmosphere (TOA), surface, and atmosphere by differencing shortwave fluxes computed with and without aerosols. The calculation includes the effects of sea-salt, sulfate, carbonaceous, and soil-dust aerosols. The aerosol distributions are obtained from a global aerosol simulation including assimilation of satellite retrievals of aerosol optical thickness (AOT). The time-dependent, three-dimensional aerosol distributions are derived with a chemical transport model driven with meteorological analyses for this period. The surface albedos are obtained from a land-surface model forced with an identical meteorological analysis and satellite-derived rainfall and insolation. These calculations are consistent with in situ observations of the surface insolation over the central Indian Ocean and with satellite measurements of the reflected shortwave radiation. The calculations show that the surface insolation under clear skies is reduced by as much as 40 W/m2 over the Indian subcontinent by natural and anthropogenic aerosols. This reduction in insolation is accompanied by an increase in shortwave flux absorbed in the atmosphere by 25 W/m2. The inclusion of clouds in the calculations changes the direct effect by less than 2 W/m2 over the Indian subcontinent, although the reduction is much larger over China. The magnitude of the difference between all-sky and clear-sky forcing is quite sensitive to the three-dimensional spatial relationship between the aerosol and cloud fields, and other estimates of the difference for the INDOEX Intensive Field Phase are as large as 5 W/m2. Copyright 2002 by the American Geophysical Union."
"12142963100;7101912085;","Simulating summertime rainfall variability in the North American monsoon region: The influence of convection and radiation parameterizations",2002,"10.1029/2001JD002047","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080837999&doi=10.1029%2f2001JD002047&partnerID=40&md5=679991837e3c5611764b3457d6728cbb","Studying the dynamics of the North American Monsoon System (NAMS) is essential for understanding and assessing the predictability of its variability. Limited-area models are potentially useful tools for this endeavor, but it is important to first identify the suite of physical parameterizations that yields the most realistic simulations. We investigate how different convection and radiation schemes influence simulations of the NAMS produced with the MM5/OSU model. We focus on the simulated intraseasonal variability associated with monsoon onset (June to July) and changes between a wet (1999) and a dry (2000) year. We test six parameterizations, including two convection schema (Grell and Kairi-Fritsch) and three radiation schema (CCM2, Cloud, and RRTM). We compare results from 2-month-long simulations to observations of circulation (NCEP Reanalysis) and rainfall (CPC and CMAP). Differences in simulated rainfall produced by the various combinations of schema are substantial, and much greater than the differences that arise from internal model variability in a three-member ensemble of Grell-RRTM simulations. The Grell-RRTM simulation produces the most realistic patterns and magnitudes of rainfall, including intraseasonal variations and the differences between the wet and dry year. Simulations using the Kain-Fritsch scheme produce too much rainfall, and fail to represent the atypical, observed decrease in precipitation from June-to-July in 2000. The CCM2 radiation scheme produces a simulated climate that is too cloudy, yielding little rainfall in the NAMS region regardless of the convection scheme used. The Cloud and RRTM radiation schemes allow for feedbacks between condensation and the water content of clouds, which yields substantial improvements in the model simulations. Copyright 2002 by the American Geophysical Union."
"57211106013;57196499374;","Predicting global aerosol size distributions in general circulation models",2002,"10.1029/2001JD001010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448966787&doi=10.1029%2f2001JD001010&partnerID=40&md5=b450d0eefef86e04e53fd94abc2bcc03","To better represent the indirect effect of aerosols on climate, a size-resolved simulation of aerosol microphysics, size distributions, number and mass concentrations has been incorporated into the GISS general circulation model (GCM). The TwO-Moment Aerosol Sectional (TOMAS) microphysics model used here conserves aerosol number as well as mass. It has high size resolution, 30 bins between 0.01 and 10 μm diameter. As a first application, a size-resolved simulation of sulfate has been performed. The model reproduces important features of the atmospheric aerosol such as number concentrations that increase with altitude and land-sea contrasts in aerosol number concentrations and size distributions. Comparisons with observations show that simulated size distributions are realistic and condensation nuclei (CN) concentrations agree with observations within about 25%. Predicted cloud condensation nuclei (CCN) concentrations are also in reasonable agreement with observations, although there are locations for which agreement would be improved by including other aerosol components such as sea salt and carbonaceous aerosols. Sensitivity scenarios show that uncertainties in nucleation and primary emissions from fossil fuels can have significant effects on predictions of CN and CCN concentrations. Copyright 2002 by the American Geophysical Union."
"6506707597;","Dependence of global radiation on cloudiness and surface albedo in Tartu, Estonia",2002,"10.1007/s00704-002-0671-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036384975&doi=10.1007%2fs00704-002-0671-y&partnerID=40&md5=b55591ea3145d8b65f37d0566c4e98f0","The dependence of global and diffuse radiation on surface albedo due to multiple reflection of radiation between the surface and the atmosphere (base of clouds) is found on the basis of data obtained at the Tartu-Tõravere Actinometric Station over the period 1955-2000. It is found that the monthly totals of global radiation increase by up to 1.38-1.88 times, particularly in the winter half-year between November and March, when snow cover albedo may be high. A semi-empirical formula is derived for calculating with sufficient accuracy the monthly totals of global radiation, considering the amount of cloudiness and the surface albedo. In the time series of the monthly total by global radiation a downward trend occurs in winter months. A decrease in global radiation by up to 20% in the past 46 years can be explained primarily by a relatively high negative trend in the snow cover duration and surface albedo (up to -0.24). As a result, days are growing darker, a new phenomenon associated with climate change, which undoubtedly affects human mood to some extent."
"7402765035;","Controlling the global weather",2002,"10.1175/1520-0477(2002)083<0241:CTGW>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036230343&doi=10.1175%2f1520-0477%282002%29083%3c0241%3aCTGW%3e2.3.CO%3b2&partnerID=40&md5=903730db1ccdc1e37cfcca0f217398e6","A system architecture to control the global weather is presented. The controller is similar in general to feedback control systems common in many industrial processes, however, it is greatly complicated by the number of degrees of freedom required to represent the atmosphere adequately, the nonlinear nature of the governing equations, the paucity of observations of the atmosphere, the difficulty of effecting control, and the requirements that control be effected at significant time lags. Nonetheless, the existence of the technology to implement the weather controller is plausible at the time range of 30-50 yr."
"35464731600;55947099700;7005399437;7006421484;7004174939;7005793702;7202772338;6603044644;","Aerosol radiative impact on spectral solar flux at the surface, derived from principal-plane sky measurements",2002,"10.1175/1520-0469(2002)059<0635:arioss>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088886439&doi=10.1175%2f1520-0469%282002%29059%3c0635%3aarioss%3e2.0.co%3b2&partnerID=40&md5=27c9bfccc611c2e5b9640c395325d7c1","Accurate measurements of the spectral solar flux reaching the surface in cloud-free conditions are required to determine the aerosol radiative impact and to test aerosol models that are used to calculate radiative forcing of climate. Spectral flux measurements are hampered in many locations by persistent broken cloud fields. Here a new technique is developed to derive the diffuse solar spectral flux reaching the surface from principal-plane measurements conducted in the last six years by the Aerosol Robotic Network (AERONET). This 50-100 instrument global network measures the principal-plane radiances in four spectral bands (0.44-1.02 μm) approximately every hour every day. These instruments also measure the spectral optical thickness and derive the aerosol size distribution and other properties from sky measurements. The advantage of the AERONET measurements is that collimated sky radiance is measured for each 1° × 1° field of view. Clouds and cloud shadows are rejected before the total sky brightness is reconstructed and the flux is derived. The results compare favorably with shadow band measurements and with aerosol models. Studied are smoke aerosol in Brazil: Saharan dust in Cape Verde; and urban-industrial pollution in Créteil, near Paris, France, and near Washington, D.C. The spectral attenuation of total (diffuse+direct) solar flux reaching the surface is given by fλ = exp(-aλ - bλτλ), where aλ is attenuation by an atmosphere with no aerosol and bλ is the aerosol attenuation coefficient. Remarkably, it is found that for these sites except for the Washington, D.C., site, the spectrally averaged value of bλ does not vary significantly from one aerosol type to another: {bλ} = 0.35 ± 0.03 (for solar zenith angle of 50°). The measured 24-h average aerosol impact on the solar flux at the surface per unit optical thickness is ΔF/Δτ = -80 W m-2 in these sites, almost independent of the aerosol type: smoke, dust, or urban-industrial pollution. In Washington, D.C., it is suspected, and demonstrated in a back of the envelope calculation, that the high amount of broken cloudiness and its correlation with the aerosol optical thickness are responsible for the apparent small aerosol forcing at the surface of ΔF/Δτ = -50 W m-2."
"7003800456;8263760800;6701338417;7004214645;","Impact of future climate and emission changes on stratospheric aerosols and ozone",2002,"10.1175/1520-0469(2002)059<0414:iofcae>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087578036&doi=10.1175%2f1520-0469%282002%29059%3c0414%3aiofcae%3e2.0.co%3b2&partnerID=40&md5=e6024e6ab854fd83113691b2c7c5fda3","Global climatological distributions of key aerosol quantities (extinction, optical depth, mass, and surface area density) are shown in comparison with results from a three-dimensional global model including stratospheric and tropospheric aerosol components. It is shown that future trends in global and regional anthropogenic emissions of sulfur dioxide may induce substantial changes in the lower stratospheric budget of sulfate aerosols: with the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios' (SRES) upper limit, ""A2"" scenario, the integrated stratospheric sulfate mass is predicted to increase from 0.15 Tg-S to 0.20 Tg-S in the year 2030, and the 1.02-μm average optical depth from 1.5 × 10-3 to 2.2 × 10-3 with a 50% increase in shortwave radiative forcing. The latter, in turn, is found to be about 23% of the total forcing by sulfate aerosols (tropospheric + stratospheric). Convective upward transport of sulfur dioxide to the tropical tropopause is found to be a key point for understanding the global distribution of sulfate in the lower stratosphere. Large increases of anthropogenic sulfur production at tropical latitudes by developing countries may explain these rather large predicted changes of stratospheric sulfate. Effects of future climate changes on stratospheric aerosol are also discussed: it is shown that the largest perturbation is on the probability of polar stratospheric cloud (PSC) formation, and that is driven primarily by greenhouse gas-induced temperature changes. In particular, the model-calculated wintertime Arctic increase of total aerosol optical depth is close to a factor of 2, with PSC optical depth and surface area density increasing by a factor of 5. This is mainly due to the predicted decrease of sudden stratospheric warming frequency in the Northern Hemisphere and the associated higher stability of the polar vortex. Enhanced ozone losses result from faster heterogeneous chemical reactions on both sulfate and PSC aerosol surfaces. The chemically driven total ozone recovery in 2030 relative to 2000 is predicted to decrease from +4.5% to +3.7% when taking into account both climate and surface emission changes: effects related to climate changes (perturbed stratospheric circulation, water vapor distribution, PSC frequency, etc.) account for about 2/3 of the calculated slow down of the O3 recovery rate."
"35558781400;7102916561;","The influence of seasonally varying atmospheric characteristics on the intensity of nocturnal cooling in a high mountain hollow",2002,"10.1175/1520-0450(2002)041<0734:TIOSVA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036647583&doi=10.1175%2f1520-0450%282002%29041%3c0734%3aTIOSVA%3e2.0.CO%3b2&partnerID=40&md5=b87e41baab607ea0b7b5ed220f6ab00a","Seasonal differences in the longwave radiation balance, diurnal cycles of humidity and cloudiness, and ambient winds during the warm season were evaluated to determine their effect on the nocturnal cooling processes of a high mountain hollow in central Japan. This hollow is located at an elevation of 2230 m at the bottom, having a depth of 50-200 m with a diameter of approximately 1 km. One of the most marked seasonal changes in the atmosphere is a reduction in the downward longwave radiation from summer to autumn due to reduced water vapor. This reduction is larger than that of the upward longwave radiation due to a reduced surface temperature. This radiation balance resulted in larger (smaller) potential intensity of radiative cooling during autumn (summer). A composite analysis of diurnal variation for days in summer and autumn showed that the humidity and cloud conditions, differing between the seasons, determined the initial timing and development of nocturnal cooling. During summer (July and August). increased downward longwave radiation in the evening caused by a combination of increased water vapor and cloud cover over the mountains, suppresses and delays cooling. In contrast, dry and fair weather conditions throughout early autumn (September and October) causes strong and continuous cooling. Despite the high potential for radiative cooling during late autumn (after mid-October), nocturnal cooling was frequently disturbed by strong ambient winds exceeding 3.6 m s-1. The weak winds during summer and early autumn have a minor effect in determining the actual cooling intensity."
"7006455000;55915206300;","Impact of improved near-infrared water vapor line data in simulations with the ECHAM4 general circulation model",2002,"10.1029/2001JD001101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-32144438700&doi=10.1029%2f2001JD001101&partnerID=40&md5=b6ac31e5a9d31e9e8bf308041fb55c6a","Recently, two new water vapor line absorption data sets have become available. First, the HITRAN 2000 data set provides updated information on several water vapor absorption lines in the near infrared. Second, an independent study initiated by the European Space Agency (ESA) created a new line data set for the spectral range between 8592 and 20000 cm-1. We investigate the impact of these new data in the near infrared as compared to HITRAN-92 on the absorption of solar radiation in the ECHAM4 general circulation model. Owing to the increased water vapor absorption in the new parameterizations, the global annual mean atmospheric absorption of solar radiation in ECHÅ M4 is increased under all skies between 3.2 and 3.7 W m-2 and between 5.0 and 5.7 W m-2 under clear skies for the different data sets. While the dynamics barely change, the hydrological cycle is slightly weaker, the cloud cover has decreased by 0.4% and the precipitation by 0.06 to 0.08 mm d-1 when the new data sets are used. Copyright 2002 by the American Geophysical Union."
"7201866492;","World ocean temperature lag time: An analysis based on glaciation data for the last two million years",2002,"10.1007/s00704-002-0687-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036961177&doi=10.1007%2fs00704-002-0687-3&partnerID=40&md5=660b05eaf180ecfed49b79f0aa82844e","It is postulated that before the influence of glaciation, it was the amount of cloud cover and the thermal inertia of the ocean that controlled the Earth's temperature. The control system went into oscillation 37 myr BP when Antarctica started moving into its present position, the temperature of the ocean and that of the rest of the environment opposing each other in antisymmetric mode. Support for this theory is provided by the observation of periods of enhanced glaciation at regular intervals. The enhancement, being attributed to harmonics with the Earth's 22,000 yr-precession and 41,000 yr-nutation cycles, allows the calculation of 23,500 yr for the period of the ocean/atmosphere-temperature cycle. The corresponding lag time between atmosphere and ocean is 11,750 yr."
"6602179148;7101644158;","Late holocene vegetation change in the Sierra Madre oriental of central Mexico",2002,"10.1006/qres.2002.2348","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036767588&doi=10.1006%2fqres.2002.2348&partnerID=40&md5=879fd036e026b718a20d951f0212d480","Past vegetation and climate changes reconstructed from a sediment core from Laguna Atezca, Molango, Mexico, provide new insights into the environmental and cultural histories of the Sierra Madre Oriental during the last 1700 yr. Pollen, microscopic charcoal, sediment chemistry, loss on ignition, and magnetic susceptibility indicate that three phases of human occupation, deforestation, and erosion (ca. A.D. 280-890, ca. A.D. 1030-1420, and ca. A.D. 1680-present) alternate with two phases of abandonment (ca. A.D. 890-1030 and ca. A.D. 1420-1680). Forest composition of the two abandonment phases differed, with cloud forest taxa (Liquidambar, Ostrya/Carpinus, Ulmus, etc.) dominating the pollen record during the first phase, and Quercus and Pinus pollen characterizing phase two. These differences may reflect a climate change in which the second phase was drier than the first; Alternatively, the increase in Pinus and Quercus may have been caused by a human-induced decline in soil fertility. The Laguna Atezca record also differs from several other Mesoamerican paleoenvironmental records in that it shows no evidence of drought at the end of the Classic Period, ca. A.D. 900. © 2002 University of Washington."
"35461763400;7004864963;13408539300;7005516464;7006863273;16238289400;6701331144;36768990600;7004593505;57203104307;7004144124;7005219614;7004035832;7003461830;6603931046;7005584424;7004027377;13408839500;57201177267;13408322600;35410947600;13408574500;6603134964;","Biogeochemical cycling of carbon, water, energy, trace gases, and aerosols in Amazonia: The LBA-EUSTACH experiments",2002,"10.1029/2001JD000524","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646498940&doi=10.1029%2f2001JD000524&partnerID=40&md5=5144e98b9a03660e7d6fa324ff638c05","The biogeochemical cycling of carbon, water, energy, aerosols, and trace gases in the Amazon Basin was investigated in the project European Studies on Trace Gases and Atmospheric Chemistry as a Contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). We present an overview of the design of the project, the measurement sites and methods, and the meteorological conditions during the experiment. The main results from LBA-EUSTACH are: Eddy correlation studies in three regions of the Amazon Basin consistently show a large net carbon sink in the undisturbed rain forest. Nitrogen emitted by forest soils is subject to chemical cycling within the canopy space, which results in re-uptake of a large fraction of soil-derived NO<inf>x</inf> by the vegetation. The forest vegetation is both a sink and a source of volatile organic compounds, with net deposition being particularly important for partially oxidized organics. Concentrations of aerosol and cloud condensation nuclei (CCN) are highly seasonal, with a pronounced maximum in the dry (burning) season. High CCN concentrations from biomass burning have a pronounced impact on cloud microphysics, rainfall production mechanisms, and probably on large-scale climate dynamics. Copyright 2002 by the American Geophysical Union."
"7402435469;","Time-split versus process-split coupling of parameterizations and dynamical core",2002,"10.1175/1520-0493(2002)130<2024:TSVPSC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036673908&doi=10.1175%2f1520-0493%282002%29130%3c2024%3aTSVPSC%3e2.0.CO%3b2&partnerID=40&md5=b6b8d12739af0a22bfe20cff48a07fab","Simulations are compared to determine the effect of the details of the coupling of the parameterization suite with the dynamical core on the simulated climate. Simulations based on time-split and process-split couplings are compared to a simulation with the original version of the NCAR Community Climate Model-3 (CCM3), which is a mixture of the two approaches. In the process-split coupling, the two components are based on the same state and their tendencies are added to produce the updated state. In the time-split coupling, the two components are calculated sequentially, each based on the state produced by the other. Overall the differences between simulations produced with the various coupling strategies are relatively small. Thus, with the time step used in the CCM3, the different time truncation errors introduced by the different coupling strategies have less effect on simulations than other arbitrary aspects of the model design. This does not imply that the time truncation errors are insignificant, just that they are similar in the cases examined here. There are, however, regions where the differences are statistically significant. The differences in the thermal balance are analyzed in these regions. The most notable differences occur between the time-split case and CCM3 over regions of Antarctica. In summer, although the temperature difference near the surface is modest, the balance of terms in the two cases is very different, with a difference in sign in the sensible heat flux between the two cases. In winter, the parameterization terms have a very strong grid-scale structure associated with parameterized clouds forming predominantly at a single grid level. The dynamics is unable to respond with a grid-scale structure. This draws into question whether the vertical resolution is adequate to properly model the physical processes."
"57206456336;55168746700;7006344866;","Budget and export of anthropogenic SOx from East Asia during continental outflow conditions",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448961273&partnerID=40&md5=debdb994c7be32a0b193551906ef6b8a","We examine the budget and export of anthropogenic SOx (SO2 and sulfate aerosol) emitted from East Asia during the late winter/early spring when continental outflow conditions dominate. Our study is based on simulations using a modified version of the China-MAP coupled regional climate/chemical transport model of Qian and Giorgi [1999]. The modification involves the addition of algorithms to treat the vertical transport and removal of SOx by convective clouds. Model-calculated anthropogenic SO2 concentrations peaked at values greater than 20 ppbv at the surface in the urban source regions of China and Korea, but averaged only about 5 pbbv in the rural areas. Midtropospheric SO2 concentrations were more than an order of magnitude less, with peak values of around 0.1-0.15 ppbv overlying the urban source regions. The model-calculated sulfate aerosol distribution is more disperse, with peak surface concentrations of 5-10 ppbv in urban source regions, and concentrations of about 3 ppbv or less in rural areas and 1 ppbv or less in the midtroposphere. The model-calculated SOx concentrations are generally within a factor of 2 of the relevant observed concentrations at nonurban sites. The calculations indicate that during the late winter/early spring period, about 50% of the anthropogenic SOx emitted over East Asia is removed from the continental source regions. Roughly 30% is wet and dry deposited onto the neighboring oceans, and the remaining 20% is exported out of the model domain. The vast majority of the exported SOx is in the form of sulfate aerosol and is transported into the midtroposphere overlying the North Pacific Ocean. The rate of SOx export, about 0.2 Tg S per month, is significant when compared to natural S sources to the North Pacific Ocean, suggesting that the export of anthropogenic SOx from East Asia is perturbing sulfate aerosol concentrations over the North Pacific Ocean during the late winter and early spring. On an intraregional basis we find that China is the largest contributor to the emission and export of SOx from East Asia. However, all the nations/continental subregions of East Asia appear to be net exporters of SOx, even those downwind of China. Copyright 2002 by the American Geophysical Union."
"6701814386;","Underestimation of solar global and diffuse radiation measured at Earth's surface",2002,"10.1029/2002JD002396","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448930538&doi=10.1029%2f2002JD002396&partnerID=40&md5=d05fc0b523879686ce8ca557a384298b","[1] Climate change perspectives intensified investigations of the radiative balance of the Earth-atmosphere system. At the top of the atmosphere, solar irradiance is known with absolute uncertainty of 0.3% and theoretical models agree with albedo measurements, but solar shortwave radiation observations at Earth's surface are less than those calculated by radiative-transfer models. This model observation discrepancy (10-25 Wm-2) led to a decade-long controversy on unexplained enhanced absorption of shortwave radiation in clear sky atmospheres as well as in clouds. Here we show evidence for underestimation of surface shortwave irradiance by traditional ""unconditioned"" global and diffuse pyranometer measurements. Reinvestigations of pyranometer calibration in conjunction with thermal offsets and pyranometer thermal control demonstrate an underestimation of clear sky solar global, as well as diffuse irradiance by 8-20 Wm-2, caused by pyranometer differential cooling. Field measurements with ""conditioned"" and ""unconditioned"" pyranometers demonstrate that the so-called night offset is present and considerably larger during daytime measurements, and this not only for diffuse but also for global pyranometer measurements. Long-term comparisons between traditional unconditioned and well-conditioned pyranometer measurements at Davos (midlatitude, 1580 m a.s.l.) show differences of several percent on the annual mean of global irradiance. Even though we are aware that measurements at higher altitudes are subject to larger thermal offsets and not representative for the global average, the results of our experiment lead us to believe that surface solar irradiance, measured in the past throughout the globe by traditional unconditioned pyranometers, is underestimated. Copyright 2002 by the American Geophysical Union."
"7005909380;6603960709;24554420100;57205776736;6701689550;56679156900;","Moisture profiles from satellite data over the Indian Ocean area",2002,"10.1080/01431160110075316","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036327113&doi=10.1080%2f01431160110075316&partnerID=40&md5=c777d73a0db761c8620ee36ff1025eed","Knowledge of three-dimensional distribution of moisture is crucial for successful numerical weather prediction in the tropics. Sparsity of moisture data over the Indian Ocean area is one of the main reasons for the poor representation of tropical diabatic forcing during the summer monsoon season. Due to the poor analysis of moisture and divergence fields over data-sparse oceanic regions in the tropics, the rainfall amounts predicted by numerical models often do not compare well with observed estimates. Prediction of flow pattern is also very sensitive to the initial moisture fields. Cloudiness cleared satellite radiances, if included in the framework of four-dimensional variational assimilation, provide the best possible source of moisture information in clear areas or above cloud top over data-sparse oceanic regions. But this may require very high computing resources, which are not available at present. An alternative is to generate synthetic moisture data from the satellite radiances using empirical statistical methods. In the present study, four different schemes of deriving moisture profiles from Indian Satellite (INSAT) and National Oceanic Atmospheric Administration (NOAA) satellite data were tested for the Indian Ocean area (30° N to 40° S, 50°. E to 130° E), for two different periods of August 1993 and June 1994 selected from the summer monsoon season. The bias and root mean square error (RMSE) values of the derived profiles are discussed in relation to available radiosonde data (island and coastal stations). The impact of this synthetic moisture on medium-range analysis-forecast system has been found to be encouraging."
"7102111067;7006592184;","Global ocean emission of dimethylsulfide predicted from biogeophysical data",2002,"10.1029/2001gb001829","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038709278&doi=10.1029%2f2001gb001829&partnerID=40&md5=e45ac4caad98b0a9e5f2c9230eea381d","Among the biosphere-atmosphere interactions that influence climate, the emission of dimethylsulfide (DMS) from the ocean plays a prominent role for its high potential in cloud albedo regulation. In order to advance in our understanding and quantification of this coupled ocean-atmosphere system, both synoptic and predictive capabilities must be largely improved. Hitherto, large-scale oceanic DMS has eluded being captured from remote sensing, correlated with synoptic variables, or simulated by mechanistic modeling. We have found a simple empirical relationship that permits global-ocean monthly distributions of DMS concentration to be computed from a combination of remotely sensed biospheric data (chlorophyll a) and climatological geophysical data (mixed layer depth). This relationship allows for the desired synopticity and predictability in the ocean-to-atmosphere sulfur flux, which we have globally quantified as 23-35 Tg S yr-1. Also, our algorithm stands in support of a biogenic-DMS/solar-radiation negative feedback and opens the door toward quantifying its strength and its response to global warming."
"7402499108;7003983225;7005617809;6603024154;35888581600;","The season peculiarities of behaviour of the long-term temperature trends in the middle atmosphere on the mid-latitudes",2002,"10.1016/S1474-7065(02)00034-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036078551&doi=10.1016%2fS1474-7065%2802%2900034-7&partnerID=40&md5=fbf81c70abaa0e586b9c58a90cc915e2","On the basis of rocket, nightglow and radiophysical measurements at heights of 25 110 km in middle latitudes the seasonal variations of the long-term temperature trends at various altitude levels are determined. At heights of 25-87 km the trends are mainly negative within all year. Only in winter period in middle and upper stratosphere the trend within several months becomes positive. At heights of 92-93 km the trend is very close to zero throughout the year. In summer period the altitude of zero trend extends downward to heights of 82-85 km, where the noctilucent clouds are usually observed. At heights of 95-110 km the trends are positive all year round. Mean annual height distribution of the temperature trend shows long-term cooling at atmospheric heights between 25 and 90 km, leading to a systematic subsidence of the upper atmospheric layers. © 2002 Elsevier Science Ltd. All rights reserved."
"7006280684;55715917500;22836973600;57197308218;7406514318;7404105326;7004169476;7103248807;7405666962;7407104838;57198966831;7103373205;6506416205;","Estimation of natural and anthropogenic contributions to twentieth century temperature change",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448985677&partnerID=40&md5=74d6c3e87845e28b2de143e0c417023d","[1] Using a coupled atmosphere/ocean general circulation model, we have simulated the climatic response to natural and anthropogenic forcings from 1860 to 1997. The model, HadCM3, requires no flux adjustment and has an interactive sulphur cycle, a simple parameterization of the effect of aerosols on cloud albedo (first indirect effect), and a radiation scheme that allows explicit representation of well-mixed greenhouse gases. Simulations were carried out in which the model was forced with changes in natural forcings (solar irradiance and stratospheric aerosol due to explosive volcanic eruptions), well-mixed greenhouse gases alone, tropospheric anthropogenic forcings (tropospheric ozone, wellmixed greenhouse gases, and the direct and first indirect effects of sulphate aerosol), and anthropogenic forcings (tropospheric anthropogenic forcings and stratospheric ozone decline). Using an ""optimal detection"" methodology to examine temperature changes near the surface and throughout the free atmosphere, we find that we can detect the effects of changes in well-mixed greenhouse gases, other anthropogenic forcings (mainly the effects of sulphate aerosols on cloud albedo), and natural forcings. Thus these have all had a significant impact on temperature. We estimate the linear trend in global mean near-surface temperature from well-mixed greenhouse gases to be 0.9 ±0.24 K/century, offset by cooling from other anthropogenic forcings of 0.4 ±0.26 K/century, giving a total anthropogenic warming trend of 0.5 ±0.15 K/century. Over the entire century, natural forcings give a linear trend close to zero. We found no evidence that simulated changes in near-surface temperature due to anthropogenic forcings were in error. However, the simulated tropospheric response, since the 1960s, is ∼50% too large. Our analysis suggests that the early twentieth century warming can best be explained by a combination of warming due to increases in greenhouse gases and natural forcing, some cooling due to other anthropogenic forcings, and a substantial, but not implausible, contribution from internal variability. In the second half of the century we find that the warming is largely caused by changes in greenhouse gases, with changes in sulphates and, perhaps, volcanic aerosol offsetting approximately one third of the warming. Wanning in the troposphere, since the 1960s, is probably mainly due to anthropogenic forcings, with a negligible contribution from natural forcings. INDEX TERMS: 1650 Global Change: Solar variability; 1694 Global Change: Instruments and techniques; 4215 Oceanography: General: Climate and interannual variability (3309);."
"7006280684;55715917500;22836973600;57197308218;7406514318;7404105326;7004169476;7103248807;7405666962;7407104838;57198966831;7103373205;6506416205;","Estimation of natural and anthropogenic contributions to twentieth century temperature change",2002,"10.1029/2000JD000028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037662417&doi=10.1029%2f2000JD000028&partnerID=40&md5=573f3fdd4939ee5000ca8a0fd2af3dbb","Using a coupled atmosphere/ocean general circulation model, we have simulated the climatic response to natural and anthropogenic forcings from 1860 to 1997. The model, HadCM3, requires no flux adjustment and has an interactive sulphur cycle, a simple parameterization of the effect of aerosols on cloud albedo (first indirect effect), and a radiation scheme that allows explicit representation of well-mixed greenhouse gases. Simulations were carried out in which the model was forced with changes in natural forcings (solar irradiance and stratospheric aerosol due to explosive volcanic eruptions), well-mixed greenhouse gases alone, tropospheric anthropogenic forcings (tropospheric ozone, well-mixed greenhouse gases, and the direct and first indirect effects of sulphate aerosol), and anthropogenic forcings (tropospheric anthropogenic forcings and stratospheric ozone decline). Using an ""optimal detection"" methodology to examine temperature changes near the surface and throughout the free atmosphere, we find that we can detect the effects of changes in well-mixed greenhouse gases, other anthropogenic forcings (mainly the effects of sulphate aerosols on cloud albedo), and natural forcings. Thus these have all had a significant impact on temperature. We estimate the linear trend in global mean near-surface temperature from well-mixed greenhouse gases to be 0.9 ± 0.24 K/century, offset by cooling from other anthropogenic forcings of 0.4 ± 0.26 K/century, giving a total anthropogenic warming trend of 0.5 ± 0.15 K/century. Over the entire century, natural forcings give a linear trend close to zero. We found no evidence that simulated changes in near-surface temperature due to anthropogenic forcings were in error. However, the simulated tropospheric response, since the 1960s, is ∼50% too large. Our analysis suggests that the early twentieth century warming can best be explained by a combination of warming due to increases in greenhouse gases and natural forcing, some cooling due to other anthropogenic forcings, and a substantial, but not implausible, contribution from internal variability. In the second half of the century we find that the warming is largely caused by changes in greenhouse gases, with changes in sulphates and, perhaps, volcanic aerosol offsetting approximately one third of the warming. Warming in the troposphere, since the 1960s, is probably mainly due to anthropogenic forcings, with a negligible contribution from natural forcings."
"14037770000;6602515302;56033135100;","Atmospheric contributions to the surface mass balance of Greenland in the HadAMS atmospheric model",2002,"10.1093/0195150163.003.0001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-32244436004&doi=10.1093%2f0195150163.003.0001&partnerID=40&md5=47279b0ff57bb9491c8a49055a17ca39","Atmospheric climate models now present powerful tools for studying atmospheric parameters relevant to the mass balance of the Greenland ice sheet, a significant uncertainty in global sea level. This study evaluates the simulations of the UK Hadley Centre atmospheric model (HadAM3) against observational data and reanalyses. HadAM3 reproduces the main precipitation patterns, but a positive bias exists in autumn over southern Greenland. The modeled North Atlantic storm track is well placed, but it and the polar vortex and hemispheric-scale wave activity are weaker than observed, which may impact on moisture flux over Greenland. Surface temperatures are 2°-3°C too warm in summer and up to 5°C too cold in winter, probably owing to the snow albedo varying too little throughout the year, and excess summer downward short-wave radiation flux and winter long-wave loss, related to insufficient cloud cover. The summer warm bias and the too coarsely represented ice sheet area lead to Greenland-mean melting being overestimated, and a negative surface mass balance is simulated. A higher-resolution ice sheet mask improves these quantities significantly. Increasing resolution is expected to remove most errors when orography and the ice sheet, particularly around the coastal margins where gradients are large, are better defined, as orographic dynamical deficiencies are minimized. A high-resolution version of the model is seen to improve the simulation of precipitation. Minor ice and snow physics improvements are needed, but the large-scale simulation produces good-quality inputs with no major bias for higher resolution limited area or downscaling models. Copyright 2002 by the American Geophysical Union."
"56144102900;56247576300;7403173064;7801421469;","The BMRC coupled general circulation model ENSO forecast system",2002,"10.1175/1520-0493(2002)130<0975:TBCGCM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036537993&doi=10.1175%2f1520-0493%282002%29130%3c0975%3aTBCGCM%3e2.0.CO%3b2&partnerID=40&md5=c4a99826426913ee3ca0a6601173fc7c","An El Niño-Southern Oscillation (ENSO) prediction system with a coupled general circulation model and an ocean data assimilation scheme has been developed at the Australian Bureau of Meteorology Research Centre (BMRC). The coupled model consists of an R21L9 version of the BMRC climate model and a global version of the Geophysical Fluid Dynamics Laboratory modular ocean general circulation model with resolution focused in the tropical region and 25 vertical levels. A univariate statistical interpolation method, with 10-day data ingestion windows, is used to assimilate ocean temperature data and initialize the coupled model. The coupling procedure does not use any flux corrections. Hindcasts have been carried out for the period 1981-95 for each season (60 in all), for up to a lead time of 12 months. This paper will describe these initial experiments and show that the skill of sea surface temperature (SST) hindcasts in the tropical Pacific is comparable to other published coupled models. The skill of the model is strongest in the central Pacific. SST skill tends to be lower during the earlier 1990s than during 1980's in the eastern Pacific but not in the central Pacific. Since the ENSO SST anomaly in the central Pacific is the most important forcing of regional and global climate anomalies, the high SST prediction skill and its insensitivity over the hindcast period in this region in this model give grounds for optimism in the use of coupled general circulation models."
"7006455000;55915206300;","Impact of improved near-infrared water vapor line data in simulations with the ECHAM4 general circulation model",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448957234&partnerID=40&md5=61d412903394f6c6e6aab776ff0f56b6","Recently, two new water vapor line absorption data sets have become available. First, the HITRAN 2000 data set provides updated information on several water vapor absorption lines in the near infrared. Second, an independent study initiated by the European Space Agency (ESA) created a new line data set for the spectral range between 8592 and 20000 cm-1. We investigate the impact of these new data in the near infrared as compared to HITRAN-92 on the absorption of solar radiation in the ECHAM4 general circulation model. Owing to the increased water vapor absorption in the new parameterizations, the global annual mean atmospheric absorption of solar radiation in ECHAM4 is increased under all skies between 3.2 and 3.7 W m-2 and between 5.0 and 5.7 W m-2 under clear skies for the different data sets. While the dynamics barely change, the hydrological cycle is slightly weaker, the cloud cover has decreased by 0.4% and the precipitation by 0.06 to 0.08 mm d-1 when the new data sets are used. Copyright 2002 by the American Geophysical Union."
"7005202019;26643408200;7006081524;7202163945;","Geostationary satellite parameters for surface energy balance",2002,"10.1016/S0273-1177(02)80296-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038558251&doi=10.1016%2fS0273-1177%2802%2980296-4&partnerID=40&md5=40830ceb1b28610a1cd25e70e3962f9d","Since January 1996, surface climate parameters for the continental US have been produced in real time at NOAA/NESDIS from GOES-8 observations, and have been made available to the NOAA/NWS National Centers for Environmental Prediction (NCEP), to the GEWEX Continental-Scale International Project (GCIP) community, as well as to the public. The products include radiative fluxes, such as surface and top of the atmosphere short-wave radiation, photosynthetically active radiation (PAR), cloud fraction, as well as surface temperature. The data can be used for evaluating corresponding parameters as produced from the NCEP (ETA) model or other meso-scale models, as inputs to hydrological models for computing evapotranspiration and snow-melt, for estimating net primary productivity, and other applications. As of July 2000, this product has become operational at NOAA/NESDIS, and it is distributed to the public within one day after being produced. In this paper provided will be background information about this product and identified will be issues that require further attention. © 2002 Published by Elsevier Science Ltd on behalf of COSPAR."
"35611825600;8903148000;6603795500;7401981172;7003723474;7102320462;7403364976;7004110606;","A microwave occultation observing system optimized to characterize atmospheric water, temperature, and geopotential via absorption",2002,"10.1175/1520-0426(2002)019<1897:AMOOSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036971339&doi=10.1175%2f1520-0426%282002%29019%3c1897%3aAMOOSO%3e2.0.CO%3b2&partnerID=40&md5=89a379cdb5d22cf57420ad3178b10596","A new remote sensing concept extrapolated from the GPS occultation concept is presented in which the signal frequencies are chosen to determine atmospheric water, temperature, and the geopotential of atmospheric pressure surfaces. Using frequencies near the 22- and 183-GHz water lines allows not only the speed of light to be derived as a GPS occultation but also derivation of profiles of absorption caused by atmospheric water. Given the additional water information, moisture and temperature as well as the geopotential of pressure surfaces can be separated and solved for. Error covariance results indicate that the accuracies of individual water profiles will be 0.5%-3% extending from roughly 1-75-km altitude. Temperature accuracies of individual profiles will be sub-Kelvin from ∼1- to 70-km altitude depending on latitude and season. Accuracies of geopotential heights of pressure will be 10-20 m from the surface to 60-km altitude. These errors are random such that climatological averages derived from this data will be significantly more accurate. Owing to the limb-viewing geometry, the along-track resolution is comparable to the 200-300 km of the GPS occultation observations, but the shorter 22- and 183-GHz wavelengths improve the diffraction-limited vertical resolution to 100-300 m. The technique can be also used to determine profiles of other atmospheric constituents such as upper-tropospheric and stratospheric ozone by using frequencies near strong lines of that constituent. The combined dynamic range, accuracy, vertical resolution, and ability to penetrate clouds far surpass that of any present or planned satellite sensors. A constellation of such sensors would provide an all-weather, global remote sensing capability including full sampling of the diurnal cycle for process studies related to water, climate research, and weather prediction in general."
"12139043600;56250250300;","Global direct radiative forcing by process-parameterized aerosol optical properties",2002,"10.1029/2001JD000886","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448964207&doi=10.1029%2f2001JD000886&partnerID=40&md5=88713eb313ba005db733065ae3dfc423","A parameterization of aerosol optical parameters is developed and implemented in an extended version of the community climate model version 3.2 (CCM3) of the U.S. National Center for Atmospheric Research. Direct radiative forcing (DRF) by monthly averaged calculated concentrations of non-sea-salt sulfate and black carbon (BC) is estimated. Inputs are production-specific BC and sulfate from Iversen and Seland [2002] and background aerosol size distribution and composition. The scheme interpolates between tabulated values to obtain the aerosol single scattering albedo, asymmetry factor, extinction coefficient, and specific extinction coefficient. The tables are constructed by full calculations of optical properties for an array of aerosol input values, for which size-distributed aerosol properties are estimated from theory for condensation and Brownian coagulation, assumed distribution of cloud-droplet residuals from aqueous phase oxidation, and prescribed properties of the background aerosols. Humidity swelling is estimated from the Köhler equation, and Mie calculations finally yield spectrally resolved aerosol optical parameters for 13 solar bands. The scheme is shown to give excellent agreement with nonparameterized DRF calculations for a wide range of situations. Using IPCC emission scenarios for the years 2000 and 2100, calculations with an atmospheric global climate model (AGCM) yield a global net anthropogenic DRF of -0.11 and 0.11 W m-2, respectively, when 90% of BC from biomass burning is assumed anthropogenic. In the 2000 scenario, the individual DRF due to sulfate and BC has separately been estimated to -0.29 and 0.19 W m-2, respectively. Our estimates of DRF by BC per BC mass burden are lower than earlier published estimates. Some sensitivity tests are included to investigate to what extent uncertain assumptions may influence these results. Copyright 2002 by the American Geophysical Union."
"7003398293;25031430500;7006399667;7007061674;","Distribution of tropical cirrus in relation to convection",2002,"10.1029/2001JD001293","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141470512&doi=10.1029%2f2001JD001293&partnerID=40&md5=08afe6c5e28da4c5b82502bb0d1669f8","Daily values of Halogen Occultation Experiment (HALOE) aerosol extinction and Climate Diagnostics Center (CDC) outgoing longwave radiation (OLR) data are used to quantify the statistical and geographical relationships of tenuous cirrus to OLR for pressure levels near the equatorial tropopause. Daily locations of deep convection are identified by analysis of the CDC OLR data. Analysis of the HALOE and CDC data demonstrates that cirrus extinction is larger over deep convection than over clearer regions by a factor of 3. Deep convection, however, occupies only 7% of the equatorial region. Ninety percent of the cirrus clouds near the tropopause are located outside of regions of deep convection. Estimates of the equivalent H<inf>2</inf>O amount in the cirras are calculated by applying transformations from extinction to volume density. Averaged over the HALOE 2 km vertical field of view, the amount of equivalent H<inf>2</inf>O in cirrus is 0.1-0.2 ppmv, which is 2 to 5% of the local gas phase H<inf>2</inf>O. Five-day back trajectories near the tropopause are calculated for 1995-2000. Half of the HALOE cirrus observations over the maritime continent are consistent with formation by convective blow-off, while the other half are consistent with in situ formation processes. Copyright 2002 by the American Geophysical Union."
"56673482900;8321530600;","Hemispheric-scale comparison and evaluation of passive-microwave snow algorithms",2002,"10.3189/172756402781817428","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036333260&doi=10.3189%2f172756402781817428&partnerID=40&md5=1567951a3b9c3bb31bc7d3e0e60d5b9f","Passive-microwave satellite remote sensing can greatly enhance large-scale snow measurements based on visible satellite data alone because of the ability to acquire data through most clouds or during darkness as well as to provide a measure of snow depth or water equivalent. This study provides preliminary results from the comparison and evaluation of several different passive-microwave algorithms. These algorithms represent examples which include both mid- and high-frequency channels, vertical and horizontal polarizations and polarization-difference approaches. In our comparisons we utilize larger, more comprehensive, validation datasets which can be expected to provide a full range of snow/climate conditions rather than limited data which may only represent a ""snapshot"" in time and space. Evaluation of snow extent derived from passive-microwave data is undertaken through comparison with the U.S. National Oceanic and Atmospheric Administration (NOAA) Northern Hemisphere snow charts which are based on visible-band satellite data. Results clearly indicate those time periods and geographic regions where the two techniques agree and where they tend to consistently disagree. Validation of snow water equivalent derived from passive-microwave data is undertaken using measurements from snowcourse transects in the former Soviet Union. Preliminary results indicate a general tendency for nearly all of the algorithms to underestimate snow water equivalent."
"6602765265;7007148434;7201610459;7403401100;35461763400;55984424900;7005601996;7006354036;7004864963;","Water-soluble organic compounds in biomass burning aerosols over Amazonia Apportionment of the chemical composition and importance of the polyacidic fraction",2002,"10.1029/2001JD000522","https://www.scopus.com/inward/record.uri?eid=2-s2.0-69149096058&doi=10.1029%2f2001JD000522&partnerID=40&md5=1b10d8533d2bca94566cf2e160f876c6","Chemical characterization was performed on carbonaceous aerosols from Rondônia in the Brazilian Amazon region as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). The sampling period (October 1999) included the peak of the burning season as well as the dry-to-wet season transition. Characterization of the carbonaceous material was performed by using a thermal combustion method. This enabled determination of aerosol total carbon (TC), black carbon (BC), and organic carbon (OC). A significant fraction of the BC material (on average about 50%) seemed to be highly refractory organic material soluble in water. A more detailed analysis of the water-soluble organic carbon (WSOC) fraction of the TC was undertaken, involving measurements of WSOC content, high-performance liquid chromatography (HPLC) separation (with UV detection) of the water-soluble components, and characterization of individual components by gas chromatography/mass spectrometry (GC/MS). The WSOC fraction accounted for 45-75% of the OC. This high WSOC fraction suggests an aerosol derived mainly from smoldering combustion. Using GC/MS, many different compounds, containing hydroxy, carboxylate, and carbonyl groups, were detected. The fraction of the WSOC identified by GC/MS was about 10%. Three classes of compounds were separated by HPLC/UV: neutral compounds (N), monocarboxylic and dicarboxylic acids (MDA), and polycarboxylic acids (PA). The sum of these three groups accounted for about 70% of the WSOC, with MDA and PA being most abundant (about 50%). Good correlations (r2 between 0.84 and 0.99) of BC water (BC after water extraction) and levoglucosan (both indicators of biomass combustion) with the watersoluble species (i.e., WSOC, N, MDA, and PA), and their increase in concentrations during the burning period provided strong evidence that biomass burning is a major source of the WSOC. Particularly interesting is that PA and therefore, probably, humic-like substances (due to their polyacidic nature) are generated in significant amounts during biomass burning. These substances, due to their water solubility and surface tensionlowering effects, may play an important role in determining the overall cloud condensation nuclei activity of biomass burning aerosols and, consequently, could be important in cloud processes and climate forcing. Copyright 2002 by the American Geophysical Union."
"55113736500;","Control of fossil-fuel particulate black carbon and organic matter, possibly the most effective method of slowing global warming",2002,"10.1029/2001JD001376","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33645599551&doi=10.1029%2f2001JD001376&partnerID=40&md5=d0c241e92a77c4339ff2564bcfb01658","Under the 1997 Kyoto Protocol, no control of black carbon (BC) was considered. Here, it is found, through simulations in which 12 identifiable effects of aerosol particles on climate are treated, that any emission reduction of fossil-fuel (f.f.) particulate BC plus associated organic matter (OM) may slow global warming more than may any emission reduction of CO2 or CH4 for a specific period. When all f.f. BC + OM and anthropogenic CO2 and CH4 emissions are eliminated together, the period is 25-100 years. It is also estimated that historical net global warming can be attributed roughly to greenhouse gas plus f.f. BC + OM warming minus substantial cooling by other particles. Eliminating all f.f. BC + OM could eliminate 20-45% of net warming (8-18% of total warming before cooling is subtracted out) within 3-5 years if no other change occurred. Reducing CO2 emissions by a third would have the same effect, but after 50-200 years. Finally, diesel cars emitting continuously under the most recent U.S. and E.U. particulate standards (0.08 g/mi; 0.05 g/km) may warm climate per distance driven over the next 100+ years more than equivalent gasoline cars. Thus, fuel and carbon tax laws that favor diesel appear to promote global warming. Toughening vehicle particulate emission standards by a factor of 8 (0.01 g/mi; 0.006 g/km) does not change this conclusion, although it shortens the period over which diesel cars warm to 13-54 years. Although control of BC + OM can slow warming, control of greenhouse gases is necessary to stop warming. Reducing BC + OM will not only slow global warming but also improve human health. Copyright 2002 by the American Geophysical Union."
"6701413579;7004299063;56744278700;35514163500;7103060756;25648525300;","Arctic Oscillation response to the 1991 Mount Pinatubo eruption: Effects of volcanic aerosols and ozone depletion",2002,"10.1029/2002JD002090","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448993338&doi=10.1029%2f2002JD002090&partnerID=40&md5=8b2ecabfe2b22f3d4f4618f9786787bf","Observations show that strong equatorial volcanic eruptions have been followed by a pronounced positive phase of the Arctic Oscillation (AO) for one or two Northern Hemisphere winters. It has been previously assumed that this effect is forced by strengthening of the equator-to-pole temperature gradient in the lower stratosphere, caused by aerosol radiative heating in the tropics. To understand atmospheric processes that cause the AO response, we studied the impact of the 1991 Mount Pinatubo eruption, which produced the largest global volcanic aerosol cloud in the twentieth century. A series of control and perturbation experiments were conducted with the GFDL SKYHI general circulation model to examine the evolution of the circulation in the 2 years following the Pinatubo eruption. In one set of perturbation experiments, the full radiative effects of the observed Pinatubo aerosol cloud were included, while in another only the effects of the aerosols in reducing the solar flux in the troposphere were included, and the aerosol heating effects in the stratosphere were suppressed. A third set of perturbation experiments imposed the stratospheric ozone losses observed in the post-Pinatubo period. We conducted ensembles of four to eight realizations for each case. Forced by aerosols, SKYHI produces a statistically significant positive phase of the AO in winter, as observed. Ozone depletion causes a positive phase of the AO in late winter and early spring by cooling the lower stratosphere in high latitudes, strengthening the polar night jet, and delaying the final warming. A positive phase of the AO was also produced in the experiment with only the tropospheric effect of aerosols, showing that aerosol heating in the lower tropical stratosphere is not necessary to force positive AO response, as was previously assumed. Aerosol-induced tropospheric cooling in the subtropics decreases the meridional temperature gradient in the winter troposphere between 30°N and 60°N. The corresponding reduction of mean zonal energy and amplitudes of planetary waves in the troposphere decreases wave activity flux into the lower stratosphere. The resulting strengthening of the polar vortex forces a positive phase of the AO. We suggest that this mechanism can also contribute to the observed long-term AO trend being caused by greenhouse gas increases because they also weaken the tropospheric meridional temperature gradient due to polar amplification of warming. Copyright 2002 by the American Geophysical Union."
"7403247998;55624487771;55699179200;7202772927;","Parameterization of wind gustiness for the computation of ocean surface fluxes at different spatial scales",2002,"10.1175/1520-0493(2002)130<2125:POWGFT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036673942&doi=10.1175%2f1520-0493%282002%29130%3c2125%3aPOWGFT%3e2.0.CO%3b2&partnerID=40&md5=f157b0afc90057ef5092414a5a58cdf9","Analysis of the Goddard cloud-ensemble (GCE) model output forced by observational data over the tropical western Pacific and eastern tropical North Atlantic has shown that ocean surface latent and sensible heat fluxes averaged in a typical global-model grid box are reproduced well using bulk algorithms with grid-box-average scalar wind speed but could be significantly underestimated under weak wind conditions using average vector wind speed. This is consistent with previous observational and modeling studies. The difference between scalar and vector wind speeds represents the subgrid wind variability (or wind gustiness) that is contributed by boundary layer large eddies, convective precipitation, and cloudiness. Based on the GCE data analysis for a case over the tropical western Pacific, a simple parameterization for wind gustiness has been developed that considers the above three factors. This scheme is found to fit well the GCE data for two other cases over the tropical western Pacific and eastern tropical North Atlantic. Its fit is also much better than that of the traditional approach that considers the contribution to wind gustiness by boundary layer large eddies alone. A simple formulation has also been developed to account for the dependence of the author's parameterization on spatial scales (or model grid size). Together, the preliminary parameterization and formulation can be easily implemented into weather and climate models with various horizontal resolution."
"7003968166;6508101255;7004200407;6506570842;","Dynamical aspects of the life cycle of the winter storm 'Lothar' (26-26 December 1999)",2002,"10.1256/003590002321042036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036130769&doi=10.1256%2f003590002321042036&partnerID=40&md5=14c79dcef5ef41bdc5cd19b0b8aaf9c3","Dynamical aspects of the life cycle of the winter storm 'Lothar' (24-26 December 1999) are investigated with the aid of the European Centre for Medium-Range Weather Forecasts analysis data and mesoscale model simulations. Neither of these datasets capture the full amplitude of the observed extreme pressure fall and surface wind speeds, but they do help identify a range of key dynamical and physical features that characterize the development of this unusual event. The analysis and interpretation is primarily based upon the evolution of the lower- and upper-level potential vorticity (PV) field complemented by three-dimensional trajectory calculations. 'Lothar' originated in the western Atlantic and travelled as a shallow low-level cyclone of moderate intensity towards Europe. This translation took place below and slightly to the south of a very intense upper-level jet and was accompanied by continuous and intense condensational heating that sustained a pronounced positive low-level PV anomaly (not unlike the concept of a 'diabatic Rossby wave'). No significant PV anomalies were evident at the tropopause level during this early phase of the life cycle. The surface cyclone intensified rapidly when the shallow cyclone approached the jet-stream axis. The circulation induced by the diabatically produced low-tropospheric PV anomaly on steeply sloping isentropic surfaces that transect the intense upper-level jet contributed significantly to the rapid formation of a narrow and deep tropopause fold. This stratospheric PV anomaly virtually merged with the diabatically produced ephemeral PV feature to form a vertically aligned tower of positive PV at the time of maximum storm intensity. A sensitivity study with a dry adiabatic hindcast simulation shows no PV-tower configuration (and only a very weak surface development) and confirms the primary importance of the cloud diabatic heating for the tropopause fold formation and the rapid 'bottom-up' intensification of 'Lothar'. A comparison of the anomalously high Atlantic sea surface temperatures in December 1999 with the water-vapour source regions for the latent-heat release that accompanied the rapid intensification phase of 'Lothar' shows a close relationship. This is of importance when discussing the possible implications of climate variability and change on the development of North Atlantic winter storms."
"26643440200;7003899619;","Evaluating the potential for retrieving aerosol optical depth over land from AVHRR pathfinder atmosphere data",2002,"10.1175/1520-0469(2002)059<0279:etpfra>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085674310&doi=10.1175%2f1520-0469%282002%29059%3c0279%3aetpfra%3e2.0.co%3b2&partnerID=40&md5=9ba6f1a83d968f7a9bf7967a004d387f","In spite of numerous studies on the remote sensing of aerosols from satellites, the magnitude of aerosol climate forcing remains uncertain. However, data from the Advanced Very High Resolution Radiometer (AVHRR) Pathfinder-Atmosphere (PATMOS) dataset-a statistical reduction of more than 19 yr of AVHRR data (1981-2000) could provide nearly 20 yr of aerosol history. PATMOS data have a daily 110 × 110 km2 equal-area grid that contains means and standard deviations of AVHRR observations within each grid cell. This research is a first step toward understanding aerosols over land with PATMOS data. Herein, the aerosol optical depth is retrieved over land at numerous Aerosol Robotic Network (AERONET) sites around the globe using PATMOS cloud-free reflectances. First, the surface bidirectional reflectance distribution function (BRDF) is retrieved using a lookup table created with a radiative transfer model and the Rahman BRDF. Aerosol optical depths are then retrieved using the retrieved BRDF parameters and the PATMOS reflectances assuming a globally constant aerosol model. This method is applied to locations with ground truth measurements, where comparisons show that the best retrievals are made by estimating the surface reflectance using observations grouped by month. Random errors (i.e., correlation coefficients and standard error of estimate) in this case are lower than those where the surface BRDF is allowed year-to-year variations. By grouping the comparison results by land cover type, it was found that less noise is expected over forested regions, with a significant potential for retrieval for 80% of all land surfaces. These results and analyses suggest that the PATMOS data can provide valuable information on aerosols over land."
"14037770000;6602515302;56033135100;","Atmospheric contributions to the surface mass balance of Greenland in the HadAM3 atmospheric model",2002,"10.1029/2001JD000389","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448937487&doi=10.1029%2f2001JD000389&partnerID=40&md5=dff0ab33a5da7f8fc509aa16c1ec6a54","Atmospheric climate models now present powerful tools for studying atmospheric parameters relevant to the mass balance of the Greenland ice sheet, a significant uncertainty in global sea level. This study evaluates the simulations of the UK Hadley Centre atmospheric model (HadAM3) against observational data and reanalyses. HadAM3 reproduces the main precipitation patterns, but a positive bias exists in autumn over southern Greenland. The modeled North Atlantic storm track is well placed, but it and the polar vortex and hemispheric-scale wave activity are weaker than observed, which may impact on moisture flux over Greenland. Surface temperatures are 2°-3°C too warm in summer and up to 5°C too cold in winter, probably owing to the snow albedo varying too little throughout the year, and excess summer downward short-wave radiation flux and winter long-wave loss, related to insufficient cloud cover. The summer warm bias and the too coarsely represented ice sheet area lead to Greenland-mean melting being overestimated, and a negative surface mass balance is simulated. A higher-resolution ice sheet mask improves these quantities significantly. Increasing resolution is expected to remove most errors when orography and the ice sheet, particularly around the coastal margins where gradients are large, are better defined, as orographic dynamical deficiencies are minimized. A high-resolution version of the model is seen to improve the simulation of precipitation. Minor ice and snow physics improvements are needed, but the large-scale simulation produces good-quality inputs with no major bias for higher resolution limited area or downscaling models. Copyright 2002 by the American Geophysical Union."
"57195843498;35509463200;7101791974;7005395607;","Satellite evidence of phenological differences between urbanized and rural areas of the eastern United States deciduous broadleaf forest",2002,"10.1007/s10021-001-0070-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036262807&doi=10.1007%2fs10021-001-0070-8&partnerID=40&md5=f7789aea2fd474ce60f1c2c6af8c957e","We used a 10-year record (1990-99) of composited and cloud-screened reflectances from the Advanced Very High Resolution Radiometer (AVHRR) to test for phenological differences between urban and rural areas in the eastern United States deciduous broadleaf forest (DBF). We hypothesized that well-documented urban heat island effects would be associated with alterations in temperature-sensitive vegetation phenology. Our objectives were thus (a) to investigate possible differences in the start of the growing season (SOS) and end of the growing season (EOS) between the urban and DBF land covers, (b) to investigate related differences in greenness amplitude and fractional cover, and (c) to develop a generalized additive model (GAM) to predict the spatial variation of observed differences. By analyzing individual 1° latitude by 1° longitude blocks, we found that, on average, urbanization is associated with a growing season expansion of 7.6 days. Most of this effect is caused by an earlier SOS in urban areas. In all cases, urban regions had lower fractional cover and greenness amplitude. The GAM model failed to produce a viable model for differences in EOS, probably because it is dominated by photoperiod controls with only a minor temperature impact. SOS differences were predicted with an accuracy of about 2.4 days, with a GAM consisting of smoothed functions of mean annual average temperature, urban fractional cover, and the urban vs DBF greenness amplitude difference. We speculate that evidence of a phenological response to warming indicates that global warming, without reduction in DBF vegetation cover and greenness amplitude, may increase carbon sequestration in mesic deciduous forests."
"55109904700;7005212820;7202208382;","Flying the TRMM Satellite in a general circulation model",2002,"10.1029/2001jd000619","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1642290762&doi=10.1029%2f2001jd000619&partnerID=40&md5=6abb2d5384a28da408b74d2c57061cdf","By incorporating the Tropical Rainfall Measurement Mission (TRMM) satellite orbital information into the Colorado State University General Circulation Model (CSU GCM), we are able to ""fly"" a satellite in the GCM and sample the simulated atmosphere in the same way as the TRMM sensors sample the real atmosphere. The TRMM-sampled statistics for precipitation and radiative fluxes at annual, intraseasonal, monthly mean, and seasonal-mean diurnal timescales are evaluated by comparing the satellite-sampled against fully sampled simulated atmospheres. The sampling rates of the TRMM sensors are significantly affected by the sensors' swath widths. The TRMM Microwave Imager (TMI) and the Visible Infrared Scanner (VIRS) sample each 2.25° × 2.25° grid box in the tropics and subtropics about once per day, but at a different local time every day, while the precipitation radar (PR) and the Clouds and the Earth's Radiant Energy System (CERES) sensor visit each grid box about once every 3 days and twice per day, respectively. Besides inadequate samplings resulting from sensors' swath widths, there is a large, systematic diurnal undersampling associated with TRMM's orbital geometry for grid boxes away from the equator. When only 1 month of TRMM data are used, this diurnal undersampling can lead to more daytime samples relative to nighttime samples in one hemisphere and more nighttime samples relative to daytime samples in the other hemisphere. The resulting sampling biases (3-6 W m-2) are very pronounced in outgoing longwave radiation (OLR) over the subtropical landmasses. The sampling errors in OLR monthly and seasonal means are less than 8 W m -2 (5%) for each 2.25° × 2.25° grid box. The OLR monthly and seasonal means are not sensitive to diurnal undersamplings associated with the TRMM orbits and sensors' swath widths. However, this is not the case for total precipitation. Diurnal undersampling could produce errors as large as 20% in the tropics and 40% in the subtropics, for the zonally averaged monthly mean rain rates. The TRMM orbits sample each 2.25° × 2.25° grid box in the tropics and subtropics 1-6 times for each hour of the day within a single season. The seasonal-mean diurnal cycles of precipitation and OLR are not well sampled for any one grid box. By either accumulating the satellite data for a long enough period, or averaging the data over a large area with a relatively uniform diurnal signal, the diurnal cycles of precipitation and OLR can be satisfactorily sampled. The effects of TRMM sampling errors on the inferred tropical-mean hydrologic cycle and radiative fluxes are also evaluated. There are strong spurious oscillations associated with TRMM's orbital geometry, with periods of 23 days and 3-4 months, in tropical-mean daily and monthly precipitation. While the relative fluctuations of the sampled OLR are negligible, the relative fluctuations of the sampled precipitation have magnitudes similar to those of the observed climate variability. Caution must therefore be used when applying TRMM observations of tropical-mean precipitation to interpret climate variations at intraseasonal and interannual scales. Copyright 2002 by the American Geophysical Union."
"7004814501;6603051342;57198204157;7006972903;57207137435;","Environmental characteristics of convective systems during TRMM-LBA",2002,"10.1175/1520-0493(2002)130<1493:ECOCSD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036612054&doi=10.1175%2f1520-0493%282002%29130%3c1493%3aECOCSD%3e2.0.CO%3b2&partnerID=40&md5=76220b353b635011dc67bcfc5bd793c3","In this paper, data collected from 51 days of continual upper-atmospheric soundings and the Tropical Ocean Global Atmosphere (TOGA) radar at Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) Hill during the Tropical Rainfall Measuring Mission component of the Brazilian Large Scale Biosphere-Atmosphere (TRMM-LBA) experiment are used to describe the mean thermodynamic and kinematic airmass properties of wet season convection over Rondonia. Brazil. Distinct multiday easterly and westerly lower-tropospheric wind regimes occured during the campaign with contrasting airmass characteristics. Westerly wind periods featured modest CAPE (1000 J kg -1), moist conditions (&gt;90% RH) extending through 700 mb, and shallow (900 mb) speed shear on the order of 10·4 s 1. This combination of characteristics promoted convective systems that featured a relatively large fraction of stratiform rainfall and weak convection nearly devoid of lightning. In contrast, easterly regime convective systems were more strongly electrified and featured larger convective rain rates and reduced stratiform rainfall fraction. These systems formed in an environment with larger CAPE (1500 J kg ·1), drier lower- and midlevel humidities (&lt;80% RH), and a wind shear layer that was both stronger (10 3 s -1) and deeper (700 mb). The time series of low- and midlevel averaged humidity exhibited marked variability between westerly and easterly regimes and was characterized by low-frequency (i.e., multiday to weekly) variations. In addition to its importance in stratiform rain formation, the humidity content directly influenced cloud cover and, thus, the degree of thermal instability present during regimes. The synoptic-scale origins of these moisture fluctuations are examined. The results reported herein provide an environmental context for ongoing dual-Doppler analyses and numerical modeling case studies of individual TRMM-LBA convective systems."
"7102604282;56099064600;7102517130;7201496259;7003931528;7404544551;6603434295;57208462871;57210717445;6603930943;56249704400;7006074773;57203053317;7005002831;7404243086;7003800456;7003543851;56250185400;7003899619;","A comparison of model- and satellite-derived aerosol optical depth and reflectivity",2002,"10.1175/1520-0469(2002)059<0441:acomas>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088716627&doi=10.1175%2f1520-0469%282002%29059%3c0441%3aacomas%3e2.0.co%3b2&partnerID=40&md5=6ab0607e665a3235f14f6aac8b880edb","The determination of an accurate quantitative understanding of the role of tropospheric aerosols in the earth's radiation budget is extremely important because forcing by anthropogenic aerosols presently represents one of the most uncertain aspects of climate models. Here the authors present a systematic comparison of three different analyses of satellite-retrieved aerosol optical depth based on the Advanced Very High Resolution Radiometer (AVHRR)-measured radiances with optical depths derived from six different models. Also compared are the model-derived clear-sky reflected shortwave radiation with satellite-measured reflectivities derived from the Earth Radiation Budget Experiment (ERBE) satellite. The three different satellite-derived optical depths differ by between -0.10 and 0.07 optical depth units in comparison to the average of the three analyses depending on latitude and month, but the general features of the retrievals are similar. The models differ by between -0.09 and +0.16 optical depth units from the average of the models. Differences between the average of the models and the average of the satellite analyses range over -0.11 to +0.05 optical depth units. These differences are significant since the annual average clear-sky radiative forcing associated with the difference between the average of the models and the average of the satellite analyses ranges between -3.9 and 0.7 W m-2 depending on latitude and is -1.7 W m-2 on a global average annual basis. Variations in the source strengths of dimethylsulfide-derived aerosols and sea salt aerosols can explain differences between the models, and between the models and satellite retrievals of up to 0.2 optical depth units. The comparison of model-generated reflected shortwave radiation and ERBE-measured shortwave radiation is similar in character as a function of latitude to the analysis of modeled and satellite-retrieved optical depths, but the differences between the modeled clear-sky reflected flux and the ERBE clear-sky reflected flux is generally larger than that inferred from the difference between the models and the AVHRR optical depths, especially at high latitudes. The difference between the mean of the models and the ERBE-analyzed clear-sky flux is 1.6 W m-2. The overall comparison indicates that the model-generated aerosol optical depth is systematically lower than that inferred from measurements between the latitudes of 10° and 30°S. It is not likely that the shortfall is due to small values of the sea salt optical depth because increases in this component would create modeled optical depths that are larger than those from satellites in the region north of 30°N and near 50°S. Instead, the source strengths for DMS and biomass aerosols in the models may be too low. Firm conclusions, however, will require better retrieval procedures for the satellites, including better cloud screening procedures, further improvement of the model's treatment of aerosol transport and removal, and a better determination of aerosol source strengths."
"55109904700;7005212820;7202208382;","Flying the TRMM Satellite in a general circulation model",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448940868&partnerID=40&md5=8569a423687d0104b9b10dae77e7618a","By incorporating the Tropical Rainfall Measurement Mission (TRMM) satellite orbital information into the Colorado State University General Circulation Model (CSU GCM), we are able to ""fly"" a satellite in the GCM and sample the simulated atmosphere in the same way as the TRMM sensors sample the real atmosphere. The TRMM-sampled statistics for precipitation and radiative fluxes at annual, intraseasonal, monthly mean, and seasonal-mean diurnal timescales are evaluated by comparing the satellite-sampled against fully sampled simulated atmospheres. The sampling rates of the TRMM sensors are significantly affected by the sensors' swath widths. The TRMM Microwave Imager (TMI) and the Visible Infrared Scanner (VIRS) sample each 2.25° × 2.25° grid box in the tropics and subtropics about once per day, but at a different local time every day, while the precipitation radar (PR) and the Clouds and the Earth's Radiant Energy System (CERES) sensor visit each grid box about once every 3 days and twice per day, respectively. Besides inadequate samplings resulting from sensors' swath widths, there is a large, systematic diurnal undersampling associated with TRMM's orbital geometry for grid boxes away from the equator. When only 1 month of TRMM data are used, this diurnal undersampling can lead to more daytime samples relative to nighttime samples in one hemisphere and more nighttime samples relative to daytime samples in the other hemisphere. The resulting sampling biases (3-6 W m-2) are very pronounced in outgoing longwave radiation (OLR) over the subtropical landmasses. The sampling errors in OLR monthly and seasonal means are less than 8 W m-2 (5%) for each 2.25° × 2.25° grid box. The OLR monthly and seasonal means are not sensitive to diurnal undersamplings associated with the TRMM orbits and sensors' swath widths. However, this is not the case for total precipitation. Diurnal undersampling could produce errors as large as 20% in the tropics and 40% in the subtropics, for the zonally averaged monthly mean rain rates. The TRMM orbits sample each 2.25° × 2.25° grid box in the tropics and subtropics 1-6 times for each hour of the day within a single season. The seasonal-mean diurnal cycles of precipitation and OLR are not well sampled for any one grid box. By either accumulating the satellite data for a long enough period, or averaging the data over a large area with a relatively uniform diurnal signal, the diurnal cycles of precipitation and OLR can be satisfactorily sampled. The effects of TRMM sampling errors on the inferred tropical-mean hydrologic cycle and radiative fluxes are also evaluated. There are strong spurious oscillations associated with TRMM's orbital geometry, with periods of 23 days and 3-4 months, in tropical-mean daily and monthly precipitation. While the relative fluctuations of the sampled OLR are negligible, the relative fluctuations of the sampled precipitation have magnitudes similar to those of the observed climate variability. Caution must therefore be used when applying TRMM observations of tropical-mean precipitation to interpret climate variations at intraseasonal and interannual scales. Copyright 2002 by the American Geophysical Union."
"7102389805;7203011505;22975069200;7102768003;7004897703;7006432091;7103133591;35619212800;6508299570;7101821307;7401530643;57213213544;14833159700;7005035762;","The jasmine pilot study",2002,"10.1175/bams-83-11-1603","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036873095&doi=10.1175%2fbams-83-11-1603&partnerID=40&md5=0ce4e01278052f70855c2885bd443d8a","The methods and initial results of an extensive pilot study, the Joint Air-Sea Monsoon Interaction Experiment (JASMINE) held in the Indian Ocean during the summer of 1999, are described. The experimental design was based on the precept that the monsoon sways back and forth from active to inactive (or break) phases and that these intraseasonal oscillations are coupled ocean-atmosphere phenomena that are important components of the monsoon system. JASMINE is the first comprehensive study of the coupled ocean-atmosphere system in the eastern Indian Ocean and the southern Bay of Bengal. Two research vessels, the NOAA ship Ronald H. Brown and the Australian research vessel Franklin, totaled 52 days of surveillance in April-June and September, with 388 conductivity-temperature-depth (CTD) casts and 272 radiosonde ascents. In addition, both ships carried identical flux systems to measure the ocean-atmosphere interaction. The Brown had five radar systems and profilers, including a cloud radar and a Doppler C-band rain radar. Active and break periods of the monsoon, and the transitions between these phases, and the onset of the 1999 South Asian summer monsoon occurred during JASMINE. The undisturbed and disturbed periods had vast differences in the net heating of the ocean, ranging from daily averages of +150 W m-2 during the former to -100 W m-2 in the latter. Accompanying these changes in the monsoon phase were distinct states of the upper ocean and the atmosphere, including complete reversals of the near-equatorial currents on the timescales of weeks. Diurnal variability occurred in both phases of the monsoon, particularly in near-surface thermodynamical quantities in undisturbed periods and in convection when conditions were disturbed. The JASMINE observations and analyses are compared with those from other tropical regions. Differences in the surface fluxes between disturbed and undisturbed periods appear to be greater in the monsoon than in the western Pacific Ocean. However, in both regions, it is argued that the configuration of convection and vertical wind shear acts as a positive feedback to accelerate low-level westerly winds. Outstanding questions and tentative plans for the future are also discussed."
"7006550762;7005117153;7004238859;7004214645;","2 × CO2 and solar variability influences on the troposphere through wave-mean flow interactions",2002,"10.2151/jmsj.80.863","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036770610&doi=10.2151%2fjmsj.80.863&partnerID=40&md5=d6765cf9385664f62d9ebcbf07feb8d5","A variety of climate forcings are now thought to be able to influence planetary wave dynamics in the troposphere by affecting the propagation of planetary waves out of the troposphere. However, this propagation pattern is sensitive to the details of the corresponding zonal wind changes. Here we discuss two forcing mechanisms that alter zonal winds and subsequent tropospheric responses: changes in atmospheric CO2 concentrations, and solar forcing in conjunction with the QBO. Increased atmospheric CO2 concentrations can be shown to influence planetary wave refraction so as to produce an intensified residual circulation in the subtropical lower stratosphere (which increases transport of tropospheric species into the stratosphere). In our GCM experiments, the low latitude response appears qualitatively robust over a wide range of tropical warming magnitudes, although the quantitative circulation change depends upon the degree of tropical warming as influenced by convection and cloud cover changes; it varies by a factor of three with a factor of three change in tropical warming. At higher latitudes, this equatorward planetary wave refraction has been associated with an increase in the high phase of the Arctic Oscillation. In the model experiments, the extratropical response depends upon the magnitude of both low and high latitude warming in the trophosphere; with SST and sea ice changes that result in a weaker Hadley Cell and greater high latitude warming, the Arctic Oscillation phase change may be negative. The QBO alters the latitudinal gradient of the zonal wind in the stratosphere, and solar heating, in association with ozone response, alters the vertical gradient of the zonal wind. Both gradients affect the refractive properties of planetary waves uniquely for each individual combination of tropical east/west winds and solar maximum/minimum activity. In the model, when we consider solar maximum compared to solar minimum conditions, the east (west) phase of the QBO results in a relative high (low) phase of the Arctic Oscillation with corresponding temperature changes. Observed and modeled surface air temperature variations calculated between the solar cycle extremes in the different QBO phases are similar in magnitude to those derived from regression of monthly data on the AO, both being on the order of observed interannual variations."
"6603742681;6603829269;7409080503;56132929700;","Trends and uncertainties in thermal calibration of AVHRR radiometers onboard NOAA-9 to NOAA-16",2002,"10.1029/2002JD002353","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751374549&doi=10.1029%2f2002JD002353&partnerID=40&md5=dfbb9f8646bdc8850bf694590a881e54","Satellite measurements from the infrared (IR) channels of the Advanced Very High Resolution Radiometer (AVHRR)/NOAA have been used to derive many important atmospheric, cloud, and surface parameters for weather prediction, climate modelling, and a variety of environmental studies. Calibration accuracy of the satellite data directly affects accuracies of the derived parameters. So far, very limited attention has been given to the calibration uncertainties of the IR channels. In this study, we analyzed the calibration data of AVHRR radiometers onboard polar orbiting satellites NOAA-9 to NOAA-16. We utilized Global Area Coverage (GAC) data, approximately one orbit per month throughout the lifetime of the instruments, available from the NOAA Satellite Active Archive (SAA). AVHRR IR channels 3B, 4, and 5 are calibrated in-flight. Calibration coefficients are derived from measurements of radiance emitted from an internal calibration target (ICT) and deep-space (SP). The overall budget of uncertainties has been evaluated using an in-flight calibration system that includes four thermal platinum resistance thermometers (PRTs) to monitor the ICT temperature. The measurement noise (NEΔT) was found to vary from 0.03 K to 0.3 K at 300 K depending on the channel and radiometer, and it increases significantly as temperature decreases. Systematic degradation of the radiometric sensitivity of the IR detectors was observed during the lifetime of a radiometer, although the annual rate of degradation is rather small (typically below 1% per year). A significant correlation between the calibration gain and temperature of a radiometer is often observed. The degradation of a sensor's radiometric sensitivity reduces the radiometric resolution of the AVHRR measurements and expands the upper limit of the measured brightness temperature. PRT measurements are subject to significant orbital variation (up to 7 K) and inconsistency for some AVHRR radiometers. The inconsistency was especially large for the AVHRR onboard NOAA-12 (up to 4 K) and NOAA-14 (up to 3 K), but it is less than 0.5 K for NOAA-15 and -16. The inconsistency may signify the presence of a thermal gradient across the ICT. Some systematic differences between PRT measurements may also indicate inaccurate characterization of the PRT sensors, for example for AVHRR/NOAA-11 and -14. The impact of the varying thermal state of the AVHRR environment on the accuracy of AVHRR in-flight thermal calibration was assessed. We found this impact to be significant (up to 0.5 K and more), and proposed a physical model to explain it. We recommend this model for AVHRR operational in-flight calibration, especially during solar radiative contamination events. Estimates of the PRT thermal response time constant were derived and found to vary between 0.5 and 1.5 min among AVHRR radiometers. Overall, we found somewhat higher uncertainties in AVHRR thermal measurements than were assumed previously. Copyright 2002 by the American Geophysical Union."
"21646972800;57200679067;7006634316;","Spatial variability of submicrometer aerosol radiative properties over the Indian Ocean during INDOEX",2002,"10.1029/2000JD000166","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346750737&doi=10.1029%2f2000JD000166&partnerID=40&md5=a6784ef616042d9d058a7ecc3856f799","In situ measurements of aerosol optical and hygroscopic properties were made over the Indian Ocean onboard the National Center for Atmospheric Research (NCAR) C-130 aircraft as part of the 1999 Intensive Field Phase (IFF) of the Indian Ocean Experiment (INDOEX). Research flights were conducted primarily in the Northern Hemisphere to the west and southwest (i.e., downwind) of the Indian subcontinent, although several flights crossed the Intertropical Convergence Zone (ITCZ) into the much cleaner Southern Hemisphere air. The optical and hygroscopic properties of submicrometer aerosols were measured most of the time, although measurements on aerosol particles smaller than ∼3 μm have also been reported. Low-altitude (0-1 km altitude) measurements of the submicrometer aerosol light scattering coefficient (σ<inf>sp</inf>, adjusted to standard temperature and pressure) in the INDOEX pollution aerosol showed a median value of 53 Mm, which is a factor of ∼2-5 higher than the median values during polluted periods at remote North American marine/coastal sites but similar to those observed at rural U.S. stations during high-aerosol periods. Submicrometer light absorption coefficients were even higher compared with the North American measurements, at 4-23 times those median values. Single-scattering albedo (ω<inf>0</inf>) measurements showed that the Indian Ocean pollution aerosol was highly absorbing, with mean values at ambient relative humidity between 0.84 and 0.87 for low-altitude flight segments conducted in the Northern Hemisphere. The aerosol hygroscopic growth factor, defined as f(RH) = σ<inf>sp (RH=85%)</inf>/σ sP (RH=40%), averaged 1.58 for flight segments below 1 km altitude and north of 5°N. This is a substantially lower/(RH) than typically observed at midcontinent Northern Hemisphere sites, although it is nearly identical to that observed at these sites when aerosols were influenced by agricultural burning or dust episodes in the surrounding area. Aerosol optical properties over the Indian Ocean also showed significant variability in both the horizontal and the vertical on very short spatial and temporal scales. Cloud-free level flight segments of only ∼10-30-min duration showed a mean variability (standard deviation/mean) in the 1-min average ambient aerosol extinction coefficient of ∼18% and a mean difference between the lowest and the highest segment extinction measurement of 39%. Vertical profiles conducted over the Northern Hemisphere Indian Ocean showed two major types of profiles. One type showed nearly constant to decreasing aerosol scattering with increasing altitude, while the other type displayed elevated aerosol layers that did not appear to be associated with boundary layer aerosols and were occasionally separated from them by relatively clear layers. These intense elevated layers, which were present in 52% of all profiles, often showed scattering coefficients several times as large as those measured near the surface. A change in synoptic-scale circulation patterns halfway through the project may have caused more of these elevated decoupled layers to be observed during the second half of the IFF and may have caused them to be observed at higher altitudes. Copyright 2002 by the American Geophysical Union."
"7003279098;7003992430;7004251824;7203015939;6603577900;","Modeling the biogeochemical cycle of dimethylsulfide in the upper ocean: A review",2001,"10.1016/S1465-9972(01)00018-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035209727&doi=10.1016%2fS1465-9972%2801%2900018-6&partnerID=40&md5=59dadd2a1da0b9765a0a0c3341b214e3","An important focus of climate-change research is the understanding of the role of ecosystems in shaping climate. Central to this aim is the identification of any feedbacks by which ecosystems may moderate anthropogenic forcing of climate. One possible ecosystem feedback involves the marine food-web and the biogenic sulfur compound dimethylsulfide (DMS). DMS is produced by algae containing the precursor compound dimethylsulfoniopropionate (DMSP), and once ventilated to the atmosphere can be transformed to sulfate aerosols and global climate. It was hypothesized that an increase in biogenically produced sulfate aerosols leading to formation of more cloud condensation nuclei (CCN), and brighter clouds, could stabilize the climate against perturbations due to greenhouse warming. Although a large database of DMS seawater measurements exist, attempts to statistically correlate DMS concentrations with other biological parameters, such as chlorophyll a or nutrients, have failed. This underscores the complex and dynamic nature of the DMS cycle, and means that simple regression-type predictive models are unlikely to be useful, except at local scales. Regional-scale simulations of the DMS cycle have involved multi-parameter, deterministic formulations based on ecological food-web approaches but with the added challenge of properly simulating the behavior of coupled sulfur and nitrogen (or carbon) cycles. Here we review the current DMS modeling approaches, outline the parameterization of key processes, and identify areas where our knowledge is poor and improvements should be made. Model skill can only be assessed against detailed regional and global data sets, however data have not always been collected in a form suitable for model parameter estimation or model calibration/validation. DMS time series, which are essential for calibration of seasonal or multi-annual simulations, are rare. We discuss the minimum requirements for a successful future integration of observational and theoretical efforts. © 2001 Elsevier Science Ltd. All rights reserved."
"55667384900;7004214645;56249704400;7006550762;","Chemistry-climate interactions in the Goddard Institute for Space Studies general circulation model 2. New insights into modeling the preindustrial atmosphere",2001,"10.1029/2000JD000090","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035726840&doi=10.1029%2f2000JD000090&partnerID=40&md5=20a75995dc24f8c378e7599f6b935e4d","We investigate the chemical (hydroxyl and ozone) and dynamical response to changing from present-day to preindustrial conditions in the Goddard Institute for Space Studies general circulation model. We identify three main improvements not included by many other works. First, our model includes interactive cloud calculations. Second, we reduce sulfate aerosol which impacts NOx partitioning hence Ox distributions. Third, we reduce sea surface temperatures and increase ocean ice coverage which impact water vapor and ground albedo, respectively. Changing the ocean data (hence water vapor and ozone) produces a potentially important feedback between the Hadley circulation and convective cloud cover. Our present-day run (run 1, control run) global mean OH value was 9.8 × 105 molecules cm-3. For our best estimate of preindustrial conditions run (run 2) which featured modified chemical emissions, sulfate aerosol, and sea surface temperatures/ocean ice, this value changed to 10.2 × 105 molecules cm-3. Reducing only the chemical emissions to preindustrial levels in run 1 (run 3) resulted in this value increasing to 10.6 × 105 molecules cm-3. Reducing the sulfate in run 3 to preindustrial levels (run 4) resulted in a small increase in global mean OH (10.7 × 105 molecules cm-3). Changing the ocean data in run 4 to preindustrial levels (run 5) led to a reduction in this value to 10.3 × 105 molecules cm-3. Mean tropospheric ozone burdens were 423, 306, 305, 305, and 310 Tg for runs 1-5, respectively. Copyright 2001 by the American Geophysical Union."
"35600074800;57216377666;","Effects of synoptic patterns on atmospheric chemistry and aerosols during the Arctic Ocean Expedition 1996",2001,"10.1029/2000JD900376","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035568945&doi=10.1029%2f2000JD900376&partnerID=40&md5=3ed0f8b6dc4568b0a6c9b5d890c5dff0","The atmospheric program on the Arctic Ocean Expedition of July through September 1996 (AOE-96) was focused on aerosol climate feedback. The expedition took place close to the saddle point between a semipersistent anticyclonic ridge from near Scandinavia to the Arctic coast of eastern Siberia and a trough from the Canadian archipelago across the pole to north central Siberia. The weather varied from anticyclonic clear-sky conditions to cyclonic cloudy conditions, and 13 identifiable migratory features (frontal bands, wave disturbances) clearly influenced local weather, clouds, atmospheric transport, and chemistry. This includes an explosive polar cyclone, born at the lateral heat gradient between Greenland and the pack ice rather than between open sea and the pack ice. The synoptic scale weather systems caused the strongest variability in trace gases (O3 in particular) and aerosols, and also strong variability in the cloud cover. The formation of air masses over the pack ice primarily depends on if there is cyclonic (convergent) or anticyclonic (divergent) flow. Cyclonic flow resulted in a modified marine air mass loaded with vapor, but with low aerosol number concentrations owing to frequent clouds and fogs and efficient cloud scavenging of the aerosol. Anticyclonic flow resulted in almost continental air masses with clear sky, long residence time over the pack ice and subsidence slowly replacing the boundary layer with free tropospheric air, low vapor concentrations, but large aerosol number in lack of efficient cloud scavenging. The synoptic variability and advection from south of the ice edge were weaker than during the predecessor International Arctic Ocean Expedition in 1991 (IAOE-91), when on average the sampled air spent 55 hours over the pack ice compared to more than 120 hours during AOE-96, owing to exceptionally high cyclone activity in 1991. This caused a large difference in atmospheric transport, chemistry, and aerosols between the two expeditions. Copyright 2001 by the American Geophysical Union."
"7005070958;55745955800;7405459515;7004325649;","Cloud structure anomalies over the tropical Pacific during the 1997/98 El Nino",2001,"10.1029/2001GL013750","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035894823&doi=10.1029%2f2001GL013750&partnerID=40&md5=c044b7fc98239c21072d101b2f420bd3","Satellite measurements of both cloud vertical structure and cloud-radiative forcing have been used to show that during the strong 1997/98 El Nino there was a substantial change in cloud vertical structure over the tropical Pacific Ocean. Relative to normal years, cloud altitudes were lower in the western portion of the Pacific and higher in the eastern portion. The reason for these redistributions was a collapse of the Walker circulation and enhanced large-scale upward motion over the eastern Pacific, both caused by the lack of a zonal sea surface temperature gradient during the El Nino. It is proposed that these cloud structure changes, which significantly impact satellite measurements of the tropical Pacific's radiation budget, would serve as one useful means of testing cloud-climate interactions in climate models."
"7202145115;7004726792;55087038900;","Tropical convection and the energy balance at the top of the atmosphere",2001,"10.1175/1520-0442(2001)014<4495:TCATEB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035894802&doi=10.1175%2f1520-0442%282001%29014%3c4495%3aTCATEB%3e2.0.CO%3b2&partnerID=40&md5=2ffbc1f81f941faa859634ac583bed24","Earth Radiation Budget Experiment (ERBE) and International Satellite Cloud Climatology Project (ISCCP) data are used in conjunction with a radiative transfer model to estimate the effect of various cloud types on the top-of-atmosphere radiation budget in convective regions of the Tropics. This analysis shows that individual convective cloud elements can have strongly positive or negative effects on the radiation balance. Nonetheless, the ensemble of cloud types that occurs in association with deep convection in the Tropics arranges itself so that the individual positive and negative contributions cancel each other when averaged over the convective cloud system. This behavior of the cloud ensemble is extremely interesting, and the authors speculate that it is indicative of feedbacks in the climate system that have not been explored adequately. A simple model is introduced that includes feedbacks that drive the net radiation in convective regions toward the net radiation in adjacent nonconvective areas. If the nonconvective regions have small cloud forcing, then this model predicts small net radiative forcing by the convective cloud ensemble. This feedback process requires that the circulations in the Tropics be sensitive to small SST gradients and that the convective cloud albedo be sensitive to the vertical motion."
"57212781009;23080010200;6603809220;","Climate feedbacks in a general circulation model incorporating prognostic clouds",2001,"10.1007/s003820100162","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035192861&doi=10.1007%2fs003820100162&partnerID=40&md5=093d858bbeb718df57ef7b1161d354e0","This study performs a comprehensive feedback analysis on the Bureau of Meteorology Research Centre General Circulation Model, quantifying all important feedbacks operating under an increase in atmospheric CO2. The individual feedbacks are analysed in detail, using an offline radiation perturbation method, looking at long- and shortwave components, latitudinal distributions, cloud impacts, non-linearities under 2xCO2 and 4xCO2 warmings and at interannual variability. The water vapour feedback is divided into terms due to moisture height and amount changes. The net cloud feedback is separated into terms due to cloud amount, height, water content, water phase, physical thickness and convective cloud fraction. Globally the most important feedbacks were found to be (from strongest positive to strongest negative) those due to water vapour, clouds, surface albedo, lapse rate and surface temperature. For the longwave (LW) response the most important term of the cloud 'optical property' feedbacks is due to the water content. In the shortwave (SW), both water content and water phase changes are important. Cloud amount and height terms are also important for both LW and SW. Feedbacks due to physical cloud thickness and convective cloud fraction are found to be relatively small. All cloud component feedbacks (other than height) produce conflicting LW/SW feedbacks in the model. Furthermore, the optical property and cloud fraction feedbacks are also of opposite sign. The result is that the net cloud feedback is the (relatively small) product of conflicting physical processes. Non-linearities in the feedbacks are found to be relatively small for all but the surface albedo response and some cloud component contributions. The cloud impact on non-cloud feedbacks is also discussed: greatest impact is on the surface albedo, but impact on water vapour feedback is also significant. The analysis method here proves to be a powerful tool for detailing the contributions from different model processes (and particularly those of the clouds) to the final climate model sensitivity."
"35784285600;","The potential impacts of global climate change on tropical montane cloud forests",2001,"10.1016/S0012-8252(01)00056-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035167462&doi=10.1016%2fS0012-8252%2801%2900056-3&partnerID=40&md5=23b5240f19592f47bc9bb14c482a6f13","Nearly every aspect of the cloud forest is affected by regular cloud immersion, from the hydrological cycle to the species of plants and animals within the forest. Since the altitude band of cloud formation on tropical mountains is limited, the tropical montane cloud forest occurs in fragmented strips and has been likened to island archipelagoes. This isolation and uniqueness promotes explosive speciation, exceptionally high endemism, and a great sensitivity to climate. Global climate change threatens all ecosystems through temperature and rainfall changes, with a typical estimate for altitude shifts in the climatic optimum for mountain ecotones of hundreds of meters by the time of CO2 doubling. This alone suggests complete replacement of many of the narrow altitude range cloud forests by lower altitude ecosystems, as well as the expulsion of peak residing cloud forests into extinction. However, the cloud forest will also be affected by other climate changes, in particular changes in cloud formation. A number of global climate models suggest a reduction in low level cloudiness with the coming climate changes, and one site in particular, Monteverde, Costa Rica, appears to already be experiencing a reduction in cloud immersion. The coming climate changes appear very likely to upset the current dynamic equilibrium of the cloud forest. Results will include biodiversity loss, altitude shifts in species' ranges and subsequent community reshuffling, and possibly forest death. Difficulties for cloud forest species to survive in climate-induced migrations include no remaining location with a suitable climate, no pristine location to colonize, migration rates or establishment rates that cannot keep up with climate change rates and new species interactions. We review previous cloud forest species redistributions in the paleo-record in light of the coming changes. The characteristic epiphytes of the cloud forest play an important role in the light, hydrological and nutrient cycles of the cloud forest and are especially sensitive to atmospheric climate change, especially humidity, as the epiphytes can occupy incredibly small eco-niches from the canopy to crooks to trunks. Even slight shifts in climate can cause wilting or death to the epiphyte community. Similarly, recent cloud forest animal redistributions, notably frog and lizard disappearances, may be driven by climate changes. Death of animals or epiphytes may have cascading effects on the cloud forest web of life. Aside from changes in temperature, precipitation, and cloudness, other climate changes may include increasing dry seasons, droughts, hurricanes and intense rain storms, all of which might increase damage to the cloud forest. Because cloud forest species occupy such small areas and tight ecological niches, they are not likely to colonize damaged regions. Fire, drought and plant invasions (especially non-native plants) are likely to increase the effects of any climate change damage in the cloud forest. As has frequently been suggested in the literature, all of the above factors combine to make the cloud forest a likely site for observing climate change effects in the near future. © 2001 Elsevier Science B.V. All rights reserved."
"6602611139;","Long-term observations of cloud cover in Cracow (1792-1999)",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035571704&partnerID=40&md5=9d667aa4196030ef45d3e941e1d2d0a3","Cracow's series of nephological observations is unique in Europe. Neither the place of observations nor the methods of estimation of the degree of cloud cover nor the definition of cloud genera have changed significantly for about one hundred years. The paper presents therefore the database on cloudiness in Cracow and its possible applications on both the local and global scale."
"6506333296;6507941861;","A dynamic-stochastic scheme for predicting large-scale precipitation and clouds",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035568864&partnerID=40&md5=5dd55e1d02d9cfffe620e281944ec887","The proposed dynamic-stochastic scheme generalizes the well-known Smagorinsky scheme by taking into account heterogeneity of cloud variables inside a mesh cell. Based on simple physical assumptions, diagnostic formulas are derived for calculating the cloud amount and water content in a mesh cell as a function of total water content. A probability function is defined from empirical data. Experiments with a global medium-range numerical weather prediction model have been conducted to forecast precipitation over Russian territory. On the basis of quantitative criteria it is shown that this scheme has an advantage over the standard scheme. The model response to a change in precipitation parametrization has been studied using a climate model developed at the Institute of Numerical Mathematics, Russian Academy of Sciences (the INM RAS model). The analysis of the results obtained and verification against reanalysis data are presented."
"6506977159;7101728297;7006442960;7004013012;7004423053;","A nonlinear impulse response model of the coupled carbon cycle-climate system (NICCS)",2001,"10.1007/s003820100170","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035669416&doi=10.1007%2fs003820100170&partnerID=40&md5=4ce4ccee55813aaa091e43a5bda2180a","Impulse-response-function (IRF) models are designed for applications requiring a large number of climate change simulations, such as multi-scenario climate impact studies or cost-benefit integrated-assessment studies. The models apply linear response theory to reproduce the characteristics of the climate response to external forcing computed with sophisticated state-of-the-art climate models like general circulation models of the physical ocean-atmosphere system and three-dimensional oceanic-plus-terrestrial carbon cycle models. Although highly computer efficient, IRF models are nonetheless capable of reproducing the full set of climate-change information generated by the complex models against which they are calibrated. While limited in principle to the linear response regime (less than about 3 °C global-mean temperature change), the applicability of the IRF model presented has been extended into the nonlinear domain through explicit treatment of the climate system's dominant nonlinearities: CO2 chemistry in ocean water, CO2 fertilization of land biota, and sublinear radiative forcing. The resultant nonlinear impulse-response model of the coupled carbon cycle-climate system (NICCS) computes the temporal evolution of spatial patterns of climate change for four climate variables of particular relevance for climate impact studies: near-surface temperature, cloud cover, precipitation, and sea level. The space-time response characteristics of the model are derived from an EOF analysis of a transient 850-year greenhouse warming simulation with the Hamburg atmosphere-ocean general circulation model ECHAM3-LSG and a similar response experiment with the Hamburg carbon cycle model HAMOCC. The model is applied to two long-term CO2 emission scenarios, demonstrating that the use of all currently estimated fossil fuel resources would carry the Earth's climate far beyond the range of climate change for which reliable quantitative predictions are possible today, and that even a freezing of emissions to present-day levels would cause a major global warming in the long term."
"6603227814;","Observation and modelling of water balance components in Northern Fennoscandia with NOAA-AVHRR and SPOT VEGETATION imagery",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-27844506143&partnerID=40&md5=8f58c7cfb0763f114ff17ebf53daf2f4","NOAA-AVHRR and SPOT VEGETATION imagery is being used for parameterization and validation of a large-scale hydrological model of Northern Fennoscandia. Due to SPOT VEGETATION's spectral observations at 1.6 , sμm snow can easily be discriminated from clouds. The thermal bands of the NOAA satellites will be used to assess spatial patterns of evapotranspiration."
"7004390019;7404105326;7402612084;57206416522;","Constraining climate model properties using optimal fingerprint detection methods",2001,"10.1007/s003820100175","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035669674&doi=10.1007%2fs003820100175&partnerID=40&md5=c513b6edbd2e27a4519beadadac1327f","We present a method for constraining key properties of the climate system that are important for climate prediction (climate sensitivity and rate of heat penetration into the deep ocean) by comparing a model's response to known forcings over the twentieth century against climate observations for that period. We use the MIT 2D climate model in conjunction with results from the Hadley Centre's coupled atmosphere-ocean general circulation model (AOGCM) to determine these constraints. The MIT 2D model, which is a zonally averaged version of a 3D GCM, can accurately reproduce the global-mean transient response of coupled AOGCMs through appropriate choices of the climate sensitivity and the effective rate of diffusion of heat anomalies into the deep ocean. Vertical patterns of zonal mean temperature change through the troposphere and lower stratosphere also compare favorably with those generated by 3-D GCMs. We compare the height-latitude pattern of temperature changes as simulated by the MIT 2D model with observed changes, using optimal finger-print detection statistics. Using a linear regression model as in Allen and Tett this approach yields an objective measure of model-observation goodness-of-fit (via the residual sum of squares weighted by differences expected due to internal variability). The MIT model permits one to systematically vary the model's climate sensitivity (by varying the strength of the cloud feedback) and rate of mixing of heat into the deep ocean and determine how the goodness-of-fit with observations depends on these factors. This provides an efficient framework for interpreting detection and attribution results in physical terms. With aerosol forcing set in the middle of the IPCC range, two sets of model parameters are rejected as being implausible when the model response is compared with observations. The first set corresponds to high climate sensitivity and slow heat uptake by the deep ocean. The second set corresponds to low sensitivities for all magnitudes of heat uptake. These results demonstrate that fingerprint patterns must be carefully chosen, if their detection is to reduce the uncertainty of physically important model parameters which affect projections of climate change."
"8732171100;6701840054;7003332823;7102630621;7201571151;","Why Is the Climate Forcing of Sulfate Aerosols so Uncertain?",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0348238206&partnerID=40&md5=28eae592e81444448dd4c10de1ba3b2a","Sulfate aerosol particles have strong scattering effect on the solar radiation transfer which results in increasing the planet albedo and, hence, tend to cool the earth-atmosphere system. Also, aerosols can act as the cloud condensation nuclei (CCN) which tend to increase the albedo of clouds and cool the global warming. The ARPEGE-Climat version 3 AGCM with FMR radiation scheme is used to estimate the direct and indirect radiative forcing of sulfate aerosols. For minimizing the uncertainties in assessing this kind of cooling effect, all kinds of factors are analyzed which have been mixed in the assessment process and may lead to the different results of the radiative forcing of aerosols. It is noticed that one of the uncertainties to assess the climate forcing of aerosols by GCM results from the different definition of radiative forcing that was used. In order to clarify this vague idea, the off-line case for considering no feedbacks and on-line case for including all the feedbacks have been used for assessment. The direct forcing of sulfate aerosols in off-line case is -0.57 W / m2 and -0.38 W / m2 for the clear sky and all sky respectively. The value of on-line case appears to be a little larger than that in off-line case chiefly due to the feedback of clouds. The indirect forcing of sulfate aerosols in off-line case is -1.4 W / m2 and -1.0 W / m2 in on-line case. The radiative forcing of sulfate aerosols has obvious regional characteristics. There is a larger negative radiative forcing over North America, Europe and East Asia. If the direct and indirect forcing are added together, it is enough to offset the positive radiative forcing induced by the greenhouse gases in these regions."
"10340975900;10338832100;","Fog precipitation on the Island of Madeira (Portugal)",2001,"10.1007/s002540100403","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0344633094&doi=10.1007%2fs002540100403&partnerID=40&md5=7db9338bcc89c86b475588e42d31733a","An important aspect of the Madeira Island's climate is its persistent nebulous covering mainly of orographic origin, which normally exists between the 600-800- to 1,600-m altitude. The object of this study is to quantify the amount of water that can be gathered by direct interception from clouds. The first results at the end of 2 years were higher than expected. The daily rates of the 'standard fog collector' ranged between 6.0 to 21.3 1/m2 of vertical collecting surface. The water collected by the rain gauges beneath Erica arborea L., ranged between 33.3 to 56.4 mm of water per day (l/m 2 per day). Depending on wind direction and speed, which is normally north-east, the highest fog water production can be 250 mm/day. Fog drip under the vegetation was three and a half times greater than the annual precipitation. © Springer-Verlag 2001."
"7006312044;35466821900;6604086676;","A prescription for controlling the air pollution resulting from the use of prescribed biomass fire: Clouds",2001,"10.1071/WF01020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035616166&doi=10.1071%2fWF01020&partnerID=40&md5=22af67b5c032582ada192822e20cb467","Forestry, conservation, wildfire risk reduction, and agricultural uses of planned or prescribed fires as a tool for meeting the needs of wildland managers are increasingly in collision at the air pollution control and climate change cross-roads. The inevitable conflict resulting from the disparate goals of users has long been the subject of a combination of both systems and ecologically integrated analysis attempting to minimize the environmental impact and maximize the economic and societal benefits of this land management technique. We offer here experimental evidence for the viability of implementing a pollution control option that could substantially reduce the particulate emissions from prescribed fires in biomass and explore some of the logical implications of these concepts. In nature, clouds and precipitation are the principal mechanisms by which the atmosphere is cleansed of particulate pollution, aerosols and smokes. We propose here, for consideration, using clouds as a part of the prescription for scheduling biomass fires. Since in most areas biomass fire is already carried out within a detailed prescriptive plan which includes meteorological forecasts, the addition of additional meteorological scheduling constraints should be acceptable to most users providing that the benefits are correspondingly large. Reducing particulate smoke emissions in all size classes by at least 50% seems practicable."
"7004586655;23065650200;35585698100;6602550636;","A GCM parameterization for bimodal size spectra and ice mass removal rates in mid-latitude cirrus clouds",2001,"10.1016/S0169-8095(01)00111-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035652325&doi=10.1016%2fS0169-8095%2801%2900111-9&partnerID=40&md5=da9276a42a8b8d7a0b370d3dc9457ec6","This study describes a parameterization for bimodal size spectra in mid-latitude cirrus, based on 996 size distribution (SD) taken from 17 flights in non-convective cirrus during ARM and FIRE intensive observation periods (IOPs). Based on recent work and results given here, the Forward Scattering Spectrometer Probe (FSSP) appears to be a viable instrument for approximating the concentration and sizes of small ice crystals for the cirrus studied here. This, in combination with new methodologies presented, allows the small particle mode of the SD (D≤ 100 μm) to be characterized. The large mode was characterized from laser imaging 2DC probe measurements. Recent work indicates that the thermal single scattering properties of ice clouds are not adequately determined by effective diameter (Deff) and ice water content (IWC) alone, and that information on SD dispersion (e.g. degree of bimodality) is also required. This parameterization satisfies this need, providing three gamma SD parameters for each mode of the bimodal distribution. Three of these six parameters are approximated as constant, while the other three are expressed in terms of cloud IWC and/or temperature (T). These simple inputs make the parameterization convenient for large scale models, such as Global Climate Models (GCMs). In addition, this parameterization provides a physically rigorous means for parameterizing the mass sedimentation rates from ice clouds in a microphysical sense. Accurate knowledge of mass removal rates is critical for predicting cirrus IWCs and radiative properties. Finally, the data in this study was used to parameterize Deff as a function of T for use in schemes parameterizing bulk short-wave single scattering properties. Uncertainties in estimating Deff drop considerably if most mid-latitude cirrus crystals are irregular, as recent studies suggest. © 2001 Elsevier Science B.V. All rights reserved."
"55637266800;7004307308;7003638866;7004647945;6603217331;7202091481;57213920653;6603125868;6506751105;6701578275;6507994712;6701571700;55933463600;7003712840;7410298977;15724139600;","A comprehensive model inter-comparison study investigating the water budget during the BALTEX-PIDCAP period",2001,"10.1007/s007030170015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035533830&doi=10.1007%2fs007030170015&partnerID=40&md5=4da8003b51ed0d04abaaa27a9fa3838f","A comparison of 8 regional atmospheric model systems was carried out for a three-month late summer/early autumn period in 1995 over the Baltic Sea and its catchment area. All models were configured on a common grid using similar surface and lateral boundary conditions, and ran in either data assimilation mode (short term forecasts plus data assimilation), forecast mode (short term forecasts initialised daily with analyses) or climate mode (no re-initialisation of model interior during entire simulation period). Model results presented in this paper were generally post processed as daily averaged quantities, separate for land and sea areas when relevant. Post processed output was compared against available analyses or observations of cloud cover, precipitation, vertically integrated atmospheric specific humidity, runoff, surface radiation and near surface synoptic observations. The definition of a common grid and lateral forcing resulted in a high degree of agreement among the participating model results for most cases. Models operated in climate mode generally displayed slightly larger deviations from the observations than the data assimilation or forecast mode integration, but in all cases synoptic events were well captured. Correspondence to near surface synoptic quantities was good. Significant disagreement between model results was shown in particular for cloud cover and the radiative properties, average precipitation and runoff. Problems with choosing appropriate initial soil moisture conditions from a common initial soil moisture field resulted in a wide range of evaporation and sensible heat flux values during the first few weeks of the simulations, but better agreement was shown at later times."
"7004423053;7005712332;6603113016;57199755749;56618721800;6602819138;22944066200;7006442960;","Global warming feedbacks on terrestrial carbon uptake under the intergovernmental Panel on Climate Change (IPCC) emission scenarios",2001,"10.1029/2000GB001375","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035693504&doi=10.1029%2f2000GB001375&partnerID=40&md5=e3e7824de10503e8261e3b03ca5703bb","A coupled physical-biogeochemical climate model that includes a dynamic global vegetation model and a representation of a coupled atmosphere-ocean general circulation model is driven by the nonintervention emission scenarios recently developed by the Intergovernmental Panel on Climate Change (IPCC). Atmospheric CO2, carbon sinks, radiative forcing by greenhouse gases (GHGs) and aerosols, changes in the fields of surface-air temperature, precipitation, cloud cover, ocean thermal expansion, and vegetation structure are projected. Up to 2100, atmospheric CO2 increases to 540 ppm for the lowest and to 960 ppm for the highest emission scenario analyzed. Sensitivity analyses suggest an uncertainty in these projections of - 10 to +30% for a given emission scenario. Radiative forcing is estimated to increase between 3 and 8 W m-2 between now and 2100. Simulated warmer conditions in North America and Eurasia affect ecosystem structure: boreal trees expand poleward in high latitudes and are partly replaced by temperate trees and grasses at lower latitudes. The consequences for terrestrial carbon storage depend on the assumed sensitivity of climate to radiative forcing, the sensitivity of soil respiration to temperature, and the rate of increase in radiative forcing by both CO2 and other GHGs. In the most extreme cases, the terrestrial biosphere becomes a source of carbon during the second half of the century. High GHG emissions and high contributions of non-CO2 agents to radiative forcing favor a transient terrestrial carbon source by enhancing warming and the associated release of soil carbon."
"56673482900;","Validation of passive microwave snow algorithms",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-27844585508&partnerID=40&md5=8f1b6b2e6ddbbd9e6ae80b6c121e55aa","Passive microwave satellite remote sensing can greatly enhance large-scale snow measurements based on visible satellite data alone because of the ability to acquire data through clouds or during darkness as well as to provide a measure of snow depth or water equivalent (SWE). This study develops a validation methodology and provides preliminary results from comparisons of several different passive microwave algorithms, including both mid- and high-frequency channels, vertical and horizontal polarizations and polarization difference approaches. Snow extent derived from passive microwave data is compared with the NOAA Northern Hemisphere snow charts. Results clearly indicate those time periods and geographical regions where the two techniques agree and where they tend to consistently disagree. Validation of SWE derived from passive microwave data is undertaken using measurements from snow course transects in the former Soviet Union. Preliminary results indicate a general tendency for nearly all of the algorithms to underestimate SWE."
"7005421521;","Monitoring wetland hydrology in Atlantic Canada using multi-temporal and multi-beam Radarsat data",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-13644274729&partnerID=40&md5=afa1dd48f41c14e3062d754fa2e87a08","Wetland complexes comprise a large percentage of ground cover in central Labrador, Canada, and contain some of the largest peatlands in North America. The region experiences long cold winters and short cool summers, resulting in a limited growth period. Fens and bogs are the dominant wetland types. The level of moisture saturation, chemistry, topography and climate influence the development of wetland systems. Slight changes in these environmental factors can significantly alter vegetation species and health. As persistent cloud cover often limits the utility of optical remotely sensed data in Atlantic Canada, the value of using the all-weather capabilities of radar data become evident. Temporal sequences of Radarsat images were acquired in May, June and August 1999. During each time period, four Radarsat scenes with incidence angles spanning 20-49° (Standard 1, 4, 7 and Fine 1) were acquired. This paper describes changes in radar backscatter as a function of incidence angle, vegetation structure and moisture conditions."
"7003663731;","Temperature regime of a small sandstone Tor, latitude 80 °N, Ellesmere Island, Nunavut, Canada",2001,"10.1002/ppp.396","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035657139&doi=10.1002%2fppp.396&partnerID=40&md5=58b14e5026783b51fd57b88f2dee6d48","Near-surface rock temperatures were recorded hourly for more than one year around a sandstone tor located on a ridge-crest at an elevation of 270 m asl. There were significant differences between air and rock temperatures except during the polar night. The SSE- and WSW-facing sides experienced large amplitude diurnal temperature cycles in the late-winter and spring, and these crossed through 0 °C from mid-April to May, well before air temperatures rose above freezing. Rock temperatures at a depth of 15 mm on the SSE-face exceeded air temperature by up to 31 °C. During most of the summer, rock faces and air temperatures remained above 0 °C. Diurnal temperature cycles were smaller in amplitude in the autumn and few cycles through 0 °C were measured because of persistent cloud cover and the absence of a radiation-reflecting snowpack. Modelling using a constant environmental lapse rate shows that although the timing and number of temperature cycles through 0 °C are influenced by altitude, the importance of rock-face orientation on the relative numbers of cycles is independent of tor elevation. The average rate of micro-weathering measured on several tors over four years was 0.012 mm a-1. No loss of larger clasts was observed at the monitored tor over 11 years suggesting that the combined rate of all types of weathering is low. Copyright © 2001 John Wiley and Sons, Ltd."
"6701879015;7005728914;7801315254;6603883615;","Climatic implications of Late Quaternary plant macrofossil assemblages from the Taymyr Peninsula, Siberia",2001,"10.1016/S0921-8181(01)00124-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035683642&doi=10.1016%2fS0921-8181%2801%2900124-2&partnerID=40&md5=d1fc1a4aa4c6b5112178a89799b0e8d4","Plant macrofossil investigations were carried out on Late-Quaternary deposits at Cape Sabler (NW shore of Lake Taymyr, Siberia). Four dated samples (three Late Pleistocene, one Holocene) rich in plant macrofossils were analysed with respect to their floristic composition. The flora of the Holocene sample is similar to the recent plant cover in the study area and is mainly characterized by subarctic and high arctic dwarf-shrubs and hydrophytes. The Pleistocene samples, radiocarbon dated to ca. 30, 27 and 18 ka BP, reflect a species-rich vegetation. The high proportion of pioneer plants within these samples indicates frequent disturbances of the vegetation cover. Furthermore, an almost complete absence of hydrophytes and swamp plants and the dominance of xerophytes, respectively, are typical for the Pleistocene vegetation from the Cape Sabler section. The presence of the tundra-steppe Crassulaceae Orostachys spinosa gives evidence for extremely cryoxeric climatic conditions in the Central Taymyr Peninsula during the Late Pleistocene. The species composition of the Pleistocene samples thus proves the predominance of a continental climate during the Weichselian, which was characterized by a decreased cloud cover, and thus increased direct solar radiation reaching the ground and extreme annual temperature variations. That would have entailed higher summer temperatures, lower precipitation, and longer vegetation periods (due to shorter snowmelt), thus, better conditions than today for the growth of plants in the study area. The higher species diversity in the Weichselian samples confirms this assumption. All these factors caused mainly aerobic soil environments and favourable conditions for seasonal heating of soils. © 2001 Elsevier Science B.V. All rights reserved."
"7004242319;7005729142;","Parameterizations of INDOEX microphysical measurements and calculations of cloud susceptibility: Applications for climate studies",2001,"10.1029/2000JD900777","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035682584&doi=10.1029%2f2000JD900777&partnerID=40&md5=312d95f820e5f4bcdd2ece4c18f55897","This study develops parameterizations of cloud microphysical properties in terms of bulk variables, provides new calculations of cloud susceptibility, and explores applications for climate studies. On the basis of cloud microphysical properties acquired during the Indian Ocean Experiment (INDOEX), the cloud effective radius re is observed to be proportional to the cube root of the ratio of cloud liquid water content (LWC) to total cloud droplet concentration Nt. A shape parameter k, depending on the skewness and dispersion of the cloud droplet size distribution, determines the proportionality constant and is highly dependent on the number of aerosols Na observed; k values range from 0.83 ± 0.07 in pristine clouds (Na &lt; 500 cm-3) to 0.73 ± 0.08 in polluted clouds (Na &gt; 1500 cm-3). Further, Nt is parameterized as a function of Na and cloud vertical velocity or LWC. Although the parameterization coefficients vary between pristine and polluted clouds, the parameterization equations are similar to those developed for other geographic locations and other cloud types, suggesting that they might be applied in climate models with varying coefficients. Using an empirically derived relation between Nt and the projected area of the cloud droplet distributions ac, the cloud susceptibilities are 2.16 times larger than those calculated using the original definition of susceptibility which does not take into account changes in cloud spectral width. Because susceptibility is shown to not vary significantly with wavelength in the solar regime, the average visible susceptibilities of 1.4×10-3 cm3 and 0.4×10-3 cm3 for pristine and polluted clouds are representative of the albedo effect. Observed susceptibilities and re agree with those calculated from the parameterization mostly within 30%, suggesting the parameterization can be applied in models to predict indirect radiative forcing. Copyright 2001 by the American Geophysical Union."
"7003541446;7401773666;23112636200;56227973100;7202698224;7005773698;6602311240;6603980201;","Closure between aerosol particles and cloud condensation nuclei at Kaashidhoo Climate Observatory",2001,"10.1029/2000JD900781","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035681634&doi=10.1029%2f2000JD900781&partnerID=40&md5=e897c07d19587608a5d1625dd04d769b","Predicting the cloud condensation nuclei (CCN) supersaturation spectrum from aerosol properties is a fairly straightforward matter, as long as those properties are simple. During the Indian Ocean Experiment we measured CCN spectra, size-resolved aerosol chemical composition, and aerosol number distributions and attempted to reconcile them using a modified form of Köhler theory. We obtained general agreement between our measured and modeled CCN spectra. However, the agreement was not as good during a time period when organic carbon comprised a quarter of the total mass of the aerosol in the submicron size range. The modeled concentrations overpredict those actually measured during that time period. This suggests that some component, presumably organic material, can inhibit the uptake of water by the electrolytic fraction of the mass. Copyright 2001 by the American Geophysical Union."
"13406672500;7103081525;7005219614;7402543304;6701697023;57202521210;35461763400;7003541446;23112636200;55463815300;7403682442;7102290666;56520921400;6602097544;7003351429;7005228425;7005729142;7005399437;57213358341;7402565763;7005920767;7005513582;7005485117;7006246996;7004242319;7006167299;7006634316;7003561442;7005773698;7006075455;7007020226;7202429440;7004490499;7006705919;55339801900;7003712971;6701689811;7401773666;21646972800;7006239404;","Indian Ocean Experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze",2001,"10.1029/2001JD900133","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035689170&doi=10.1029%2f2001JD900133&partnerID=40&md5=a12de96448ea99de3d3eb4a65fc590a5","Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocean, and South and Southeast Asia. The Indian Ocean Experiment (INDOEX) documented this Indo-Asian haze at scales ranging from individual particles to its contribution to the regional climate forcing. This study integrates the multiplatform observations (satellites, aircraft, ships, surface stations, and balloons) with one- and four-dimensional models to derive the regional aerosol forcing resulting from the direct, the semidirect and the two indirect effects. The haze particles consisted of several inorganic and carbonaceous species, including absorbing black carbon clusters, fly ash, and mineral dust. The most striking result was the large loading of aerosols over most of the South Asian region and the North Indian Ocean. The January to March 1999 visible optical depths were about 0.5 over most of the continent and reached values as large as 0.2 over the equatorial Indian ocean due to long-range transport. The aerosol layer extended as high as 3 km. Black carbon contributed about 14% to the fine particle mass and 11% to the visible optical depth. The single-scattering albedo estimated by several independent methods was consistently around 0.9 both inland and over the open ocean. Anthropogenic sources contributed as much as 80% (±10%) to the aerosol loading and the optical depth. The in situ data, which clearly support the existence of the first indirect effect (increased aerosol concentration producing more cloud drops with smaller effective radii), are used to develop a composite indirect effect scheme. The Indo-Asian aerosols impact the radiative forcing through a complex set of heating (positive forcing) and cooling (negative forcing) processes. Clouds and black carbon emerge as the major players. The dominant factor, however, is the large negative forcing (-20 ± 4 W m-2) at the surface and the comparably large atmospheric heating. Regionally, the absorbing haze decreased the surface solar radiation by an amount comparable to 50% of the total ocean heat flux and nearly doubled the lower tropospheric solar heating. We demonstrate with a general circulation model how this additional heating significantly perturbs the tropical rainfall patterns and the hydrological cycle with implications to global climate. Copyright 2001 by the American Geophysical Union."
"7004247477;7201574108;","Regional modelling of anthropogenic sulphur in Southeast Asia",2001,"10.1016/S1352-2310(01)00375-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035162135&doi=10.1016%2fS1352-2310%2801%2900375-2&partnerID=40&md5=15bdf7672be9f57b1b004aa644b6c42b","A co-operative research project between the Malaysian Meteorological Service (MMS) and the Swedish Meteorological and Hydrological Institute (SMHI) focussing on the usage of an atmospheric transport and chemistry model, has just been initiated. Here, we describe the main features of the dispersion model and discuss a first set of calculations in light of available measurements of sulphuric species in Southeast Asia. According to our results, anthropogenic sulphur concentrations and depositions are particularly high near the large cities of the region, around a metal smelter in the southern Philippines, and in a region extending from northern Vietnam into southeastern China. These areas coincide with the high-emissions regions of Southeast Asia and we tentatively conclude that regional transport of acidifying species is not as far-reaching as in the mid-latitudes. From our calculations, and from supporting measurements we conclude that most of rural Southeast Asia is not yet severely affected by anthropogenic sulphur, but given the rapid rate of economical development in this region the situation may deteriorate quickly. Areas that are particularly at risk include the large cities, northern Vietnam, most of central Thailand, most of peninsular Malaysia, eastern Sumatra and parts of Java, all of which receive total-sulphur depositions in excess of 0.5gSm-2yr-1. Our model simulates sulphate in precipitation in accordance with measurements, but it has a tendency to overestimate atmospheric SO2. It remains to be investigated whether this is a problem in the model formulation or a result of unrepresentative sampling. An immediate continuation of this study should be performed with higher spatial resolution than the currently used 100×100km2. Other imperfections in this model study, which should be addressed in future work, include parameterised vertical transport in deep convective clouds, the influence of natural emissions (primarily from volcanoes) on the concentration and deposition of sulphuric species, and the year-to-year variability of the driving meteorological conditions. Copyright © 2001 Elsevier Science Ltd."
"7003683808;7202496599;57197372739;","The University of Illinois, Urbana-Champaign three-dimensional stratosphere-troposphere general circulation model with interactive ozone photochemistry: Fifteen-year control run climatology",2001,"10.1029/2000JD000058","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035652153&doi=10.1029%2f2000JD000058&partnerID=40&md5=c06e6b38047f6da9b36fac90191edab5","A new University of Illinois at Urbana-Champaign 24-layer troposphere-stratosphere general circulation model with interactive photochemistry is presented. We document here the results of a 15-year-long control run of the model and an evaluation of its performance. The ability of the model to simulate the Northern Hemisphere polar vortex has been improved because of the modification of the gravity wave drag parameterization. The extension and update of the chemical routine improved the simulated species distributions. As a result, the agreement of the simulated fields with observations is within 20% for total ozone and other species, 5 K for temperature, and 10 m s-1 for zonal wind over most of the atmosphere. The model simulates well the appearance of polar stratospheric clouds and the ""ozone hole"" over Antarctica. However, in some particular points the model results are unrealistic. These are (1) a cold bias (∼25 K) in the Southern Hemisphere lower stratosphere during austral summer, (2) a warm bias (∼20 K) in the middle stratosphere during austral winter, (3) a warm bias (∼10 K) near the stratopause in the tropics, and (4) a persistent cold bias of up to 8 K in the lowermost stratosphere almost everywhere over the globe. These problems may be due to the lack of a nonorographic gravity wave drag parameterization in the model, the influence of the top boundary conditions, and/or some problems with model treatment of the zonal wind-planetary wave interaction in the stratosphere. Despite these few shortcomings, the model is now ready to be applied to several climate-chemistry issues such as future ozone layer changes due to increasing greenhouse gas concentrations, the atmospheric influence of volcanic eruptions, and sun-climate relations. Copyright 2001 by the American Geophysical Union."
"7003596162;7102693151;57198955785;57204298997;55947652600;","Cloudy weather may have saved Society Island reef corals during the 1998 ENSO event",2001,"10.3354/meps222209","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035813990&doi=10.3354%2fmeps222209&partnerID=40&md5=1ecc1ac7e957c34e4fc78f26e78fddc4","During the 1998 El Niño-Southern Oscillation (ENSO) event, mass coral bleaching in French Polynesia was patchy at a scale of 100s of km. Bleaching was extensive in parts of the Tuamotu archipelago (creating up to 99% coral mortality) but extremely mild in the Society Islands (Tahiti, Moorea), ca 350 km to the south-west, despite sea surface temperature (SST) anomalies being of similar magnitude to previous years in which mass bleaching occurred. We examine whether environmental variables account for this unexpected paucity of bleaching using a 50 yr record of SST, a 17 yr record of daily wind and cloud cover, and a 17 yr record of monthly sun hours. Records from Tahiti reveal that exceptionally high cloud cover significantly reduced the number of sun hours during the summer of 1998. Quadratic discriminant analyses of annual bleaching occurrence based on up to 3 predictors (cumulative degree heating months, wind speed, and cloud cover during periods of elevated summer SST) only predicted the correct bleaching scenario for 1998 when cloud cover was added to the function. The results demonstrate that the interactive effect of cloud cover can reverse the bleaching predictions of such statistical models. We suggest that reduced radiative stress, resulting from high cloud cover, may have prevented large-scale coral bleaching in 1998."
"17137363200;7004518227;35593927100;7006393951;6603331306;","Modeling climatic effects of anthropogenic carbon dioxide emissions: Unknowns and uncdertainties",2001,"10.3354/cr018259","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035798715&doi=10.3354%2fcr018259&partnerID=40&md5=55ac8ffa59443ffbff905da6ec1ad843","A likelihood of disastrous global environmental consequences has been surmised as a result of projected increases in anthropogenic greenhouse gas emissions. These estimates are based on computer climate modeling, a branch of science still in its infancy despite recent substantial strides in knowledge. Because the expected anthropogenic climate forcings are relatively small compared to other background and forcing factors (internal and external), the credibility of the modeled global and regional responses rests on the validity of the models. We focus on this important question of climate model validation. Specifically, we review common deficiencies in general circulation model (GCM) calculations of atmospheric temperature, surface temperature, precipitation and their spatial and temporal variability. These deficiencies arise from complex problems associated with parameterization of multiply interacting climate components, forcings and feedbacks, involving especially clouds and oceans. We also review examples of expected climatic impacts from anthropogenic CO2 forcing. Given the host of uncertainties and unknowns in the difficult but important task of climate modeling, the unique attribution of observed current climate change to increased atmospheric CO2 concentration, including the relatively well-observed latest 20 yr, is not possible. We further conclude that the incautious use of GCMs to make future climate projections from incomplete or unknown forcing scenarios is antithetical to the intrinsically heuristic value of models. Such uncritical application of climate models has led to the commonly held but erroneous impression that modeling has proven or substantiated the hypothesis that CO2 added to the air has caused or will cause significant global warming. An assessment of the merits of GCMs and their use in suggesting a discernible human influence on global climate can be found in the joint World Meteorological Organisation and United Nations Environmental Programme's Intergovernmental Panel on Climate Change (IPCC) reports (1990, 1995 and the upcoming 2001 report). Our review highlights only the enormous scientific difficulties facing the calculation of climatic effects of added atmospheric CO2 in a GCM. The purpose of such a limited review of the deficiencies of climate model physics and the use of GCMs is to illuminate areas for improvement. Our review does not disprove a significant anthropogenic influence on global climate."
"56520921400;","Parameterization of generalized cloud overlap for radiative calculations in general circulation models",2001,"10.1175/1520-0469(2001)058<3224:POGCOF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035515167&doi=10.1175%2f1520-0469%282001%29058%3c3224%3aPOGCOF%3e2.0.CO%3b2&partnerID=40&md5=1610b77fa0c598749e8714d9f6f9b361","New radiative parameterizations have been developed for the National Center for Atmospheric Research (NCAR) Community Atmospheric Model (CAM). The CAM is the next version of the NCAR Community Climate Model (CCM). This paper describes the generalized treatment of vertical cloud overlap in the radiative calculations. The new parameterizations compute the shortwave and longwave fluxes and heating rates for random overlap, maximum overlap, or an arbitrary combination of maximum and random overlap. The specification of the type of overlap is identical for the two bands, and it is completely separated from the radiative parameterizations. In the prototype of CAM (CAM 0.1), adjacent cloud layers are maximally overlapped and groups of clouds separated by cloud-free layers are randomly overlapped. The introduction of the generalized overlap assumptions permits more realistic treatments of cloud-radiative interactions. The parameterizations are based upon representations of the radiative transfer equations that are more accurate than previous approximations. These techniques increase the computational cost of the radiative calculations by approximately 30%. The methodology has been designed and validated against calculations based upon the independent pixel approximation (IPA). The solution techniques and validation procedure are described in detail. The hourly radiative fluxes and heating rates from the parameterizations and IPA have been compared for a 1-yr integration of CAM. The mean and rms errors in the hourly longwave top of the atmosphere (TOA) fluxes are -0.006 ± 0.066 W m-2, and the corresponding errors in the shortwave TOA fluxes are -0.20 ± 1.58 W m-2. Heating rate errors are O(10-3) K day-1. In switching from random to maximum/random overlap, the largest changes in TOA shortwave fluxes occur over tropical continental areas, and the largest changes in TOA longwave fluxes occur in tropical convective regions. The effects on global climate are determined largely by the instantaneous changes in the fluxes rather than feedbacks related to cloud overlap."
"35509639400;7006184606;","A parameterization of the cloudiness associated with cumulus convection; evaluation using TOGA COARE data",2001,"10.1175/1520-0469(2001)058<3158:APOTCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035515160&doi=10.1175%2f1520-0469%282001%29058%3c3158%3aAPOTCA%3e2.0.CO%3b2&partnerID=40&md5=0b96e1415814aa8847062c89f91b0f71","A new parameterization of the cloudiness associated with cumulus convection is proposed for use in climate models. It is based upon the idea that the convection scheme predicts the local concentration of condensed water (the in-cloud water content) produced at the subgrid scale, and that a statistical cloud scheme predicts how this condensed water is spatially distributed within the domain. The cloud scheme uses a probability distribution function (PDF) of the total water whose variance and skewness coefficient are diagnosed from the amount of condensed water produced at the subgrid scale by cumulus convection and at the large scale by supersaturation, from the degree of saturation of the environment, and from the lower bound of the total water distribution that is taken equal to zero. This parameterization is used in a single-column model forced by the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) data, and including the cumulus convection scheme of Emanuel whose humidity prediction has been optimized using these data. Simulations are carried out during the 120 days of operation of the TOGA COARE intensive observation period. The model is able to reproduce some of the main characteristics of the cloudiness observed over the warm pool. This includes the occurrence of different populations of clouds (shallow, midlevel, and deep convective), a minimum cloud cover between 600 and 800 hPa, some relationship between the distribution of cloud tops and the presence of stable atmospheric layers, the formation of long-lasting upper-tropospheric anvils associated with the maturation of the convective cloud systems, and the presence of an extensive layer of thin cirrus clouds just below the tropopause. Nevertheless, shallow-level clouds are likely to be understimated. The behavior of the predicted cloud fields is consistent with some statistical features suggested by cloud-resolving model simulations of tropical cloud systems over oceans. The radiative fluxes calculated interactively by the model from the predicted profiles of humidity, temperature, and clouds are in reasonable agreement with satelite data. Sea surface temperatures predicted by the model using its own radiative and turbulent fluxes calculated at the ocean surface differ from observations by a few tenths of a degree. Sensitivity tests show that the performance of the cloudiness parameterization does not critically depend upon the choice of the PDF. On the other hand, they show that the prediction of radiative fluxes is improved when the statistical moments of the PDF are predicted from both large-scale variables and subgrid-scale convective activity rather than from large-scale variables only."
"55949545500;","Modelling topography with SAR interferometry: Illustrations of a favourable and less favourable environment",2001,"10.1016/S0098-3004(00)00158-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035501522&doi=10.1016%2fS0098-3004%2800%2900158-8&partnerID=40&md5=14b0882de22652e4bc16ec3f6f1a66ed","Radar remote sensing has faced an increasing interest in a wide variety of Earth observation studies during this last decade. This interest is notably related to the necessity to map areas where the cloud cover does not allow the use of classical optical sensors, or the increasing interest for ocean studies. Amongst the large number of radar applications different techniques exist for mapping the topography. Digital elevation models (DEMs) are required in a growing field of applications and especially in earth sciences where their use in structural geology, environmental geology or engineer geology has become essential. In this paper, we discuss the results obtained with SAR interferometry (InSAR) from two different environments and for two specific applications. The first is the study of the recent and present day tectonic evolution of the Rukwa rift (SW Tanzania) and the other, the study of the topography from the Bulusan volcano (Philippines). In the first situation, interferometry gave encouraging results. The computed InSAR DEM helped to identify unsuspected lineaments closely related to tectonic. In the Philippines, SAR interferometry failed to provide DEM because of the temporal decorrelation due to the dense vegetation and the humid climate. Radargrammetry or radar stereoscopy was tested with few different geometries, but the obtained results were evidencing the need in accurate ground control points. Discrepancies with regard to the reference computed from existing 1/50,000 topographic maps are reported to be larger where no or too few GCPs were identified. © 2001 Elsevier Science Ltd. All rights reserved."
"57212781009;","On the vertical extent of atmospheric feedbacks",2001,"10.1007/s003820000111","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034835669&doi=10.1007%2fs003820000111&partnerID=40&md5=b618e874dd75e2a27a444164716040cd","This study addresses the question: what vertical regions contribute the most to water vapor, surface temperature, lapse rate and cloud fraction feedback strengths in a general circulation model? Multi-level offline radiation perturbation calculations are used to diagnose the feedback contribution from each model level. As a first step, to locate regions of maximum radiative sensitivity to climate changes, the top of atmosphere radiative impact for each feedback is explored for each process by means of idealized parameter perturbations on top of a control (1 × CO2) model climate. As a second step, the actual feedbacks themselves are calculated using the changes modelled from a 2 × CO2 experiment. The impact of clouds on water vapor and lapse rate feedbacks is also isolated using 'clear sky' calculations. Considering the idealized changes, it is found that the radiative sensitivity to water vapor changes is a maximum in the tropical lower troposphere. The sensitivity to temperature changes has both upper and lower tropospheric maxima. The sensitivity to idealized cloud changes is positive (warming) for upper level cloud increases but negative (cooling) for lower level increases, due to competing long and shortwave effects. Considering the actual feedbacks, it is found that water vapor feedback is a maximum in the tropical upper troposphere, due to the large relative increases in specific humidity which occur there. The actual lapse rate feedback changes sign with latitude and is a maximum (negative) again in the tropical upper troposphere. Cloud feedbacks reflect the general decrease in low- to mid-level low-latitude cloud, with an increase in the very highest cloud. This produces a net positive (negative) shortwave (longwave) cloud feedback. The role of clouds in the strength of the water vapor and lapse rate feedbacks is also discussed."
"7003582587;","Using a cloud-resolving model to study the effects of subgrid-scale variations in relative humidity on direct sulphate-aerosol forcing",2001,"10.1256/smsqj.57709","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035472299&doi=10.1256%2fsmsqj.57709&partnerID=40&md5=a60d746fa3fddb62cd42d6d3267e8fab","Cloud-resolving model simulations over a tropical ocean and a mid-latitude continental region have been used to investigate the influence of subgrid-scale variations of relative humidity on the direct radiative forcing of sulphate aerosols. Offline radiation calculations based on output from a cloud-resolving model, with and without sulphate aerosols included, are used to calculate the direct radiative forcing of the aerosol. This forcing is compared with results from single-column radiation calculations typical of those produced by a climate model. The results from this idealized study show that a typical climate model can underestimate the direct radiative forcing of aerosols by up to 80%. The errors in a climate-model calculation are largest when the mean relative humidity is high or there are moist regions within a drier domain; this is usually reflected in a larger standard deviation of the relative humidity. Over the more humid tropical ocean, a climate model may underestimate the direct radiative forcing of sulphate aerosols by 43%, on average (ranging between 30% and 80%). Over the drier continental mid-latitude region the average error is only 10%, but instantaneous values can exceed 50% during times when both the mean relative humidity and its standard deviation are large; this is typically close to convective events."
"7404142321;7407104838;57198966831;7004764167;6506416205;","The response of the climate system to the indirect effetcs of anthropogenic sulfate aerosol",2001,"10.1007/s003820100150","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034820197&doi=10.1007%2fs003820100150&partnerID=40&md5=48877b4cfa4e3b26449cfd0961761271","The indirect effects of anthropogenic sulfate aerosols on the albedo and lifetime of clouds may produce a significant impact on the climate system. A 'state of the art' general circulation model (GCM) which includes an interactive sulfur cycle and a physically based cloud microphysics scheme is coupled to a mixed-layer ocean model in order to study the impact of the indirect effects on the coupled climate system. The linearity of the two indirect effects on the model response is also investigated by including each effect separately in the model. The response of the sea surface temperatures (SSTs) and sea ice is found to provide an important feedback on the cooling at high latitudes and the change in meridional SST gradient results in a southward shift of the inter-tropical convergence zone (ITCZ). The sensitivity of the model to the forcing from the indirect effects of sulfate aerosol is found to be similar to, but slightly weaker than that obtained from a doubling of CO2."
"7003582587;7401584839;","Sensitivity studies using a cloud-resolving model simulationof the tropical West Pacific",2001,"10.1256/smsqj.57704","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035472614&doi=10.1256%2fsmsqj.57704&partnerID=40&md5=d71d756053141acd1a4bc769b8894325","It is important to understand the variability of results which can be produced in a cloud-resolving model (CRM) before using its output to develop parametrizations. In the work presented here a broad range of sensitivity experiments are carried out so that the significance of each change to the model can be put into context. Changes to the parametrization of microphysics and radiation in the CRM are considered along with the influence of dimensionality, horizontal resolution and domain size. Further detailed sensitivity studies are then carried out to investigate the impact of the spatial and temporal distribution of the radiative heating. The results presented show that, out of all the sensitivity studies considered, no particular feature or physical parametrization in a CRM dominates. The domain size, horizontal grid length, use of a third dimension and parametrization of microphysics all significantly impact the simulation in some way. Radiative heating has a large impact on the simulation because it dominates over the large-scale forcing above 8 km. However, the magnitude of this impact is strongly dependent on other aspects of the model, such as the choice of microphysical scheme. A diurnal cycle, which is inherent in the large-scale forcing, is not significantly enhanced by radiation in the CRM. However, accounting for the temporal and spatial variability in the radiative heating is important because neglecting this is shown to overestimate the strength of convection."
"7102636922;55571729000;7006146499;7005557215;","An investigation of the sensitivity of a land surface model to climate change using a reduced form model",2001,"10.1007/s003820000135","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034826960&doi=10.1007%2fs003820000135&partnerID=40&md5=ef5df2176d06937cfe7d362eeb3dfe23","In an illustration of a model evaluation methodology, a multivariate reduced form model is developed to evaluate the sensitivity of a land surface model to changes in atmospheric forcing. The reduced form model is constructed in terms of a set of ten integrative response metrics, including the timing of spring snow melt, sensible and latent heat fluxes in summer, and soil temperature. The responses are evaluated as a function of a selected set of six atmospheric forcing perturbations which are varied simultaneously, and hence each may be thought of as a six-dimensional response surface. The sensitivities of the land surface model are interdependent and in some cases illustrate a physically plausible feedback process. The important predictors of land surface response in a changing climate are the atmospheric temperature and downwelling longwave radiation. Scenarios characterized by warming and drying produce a large relative response compared to warm, moist scenarios. The insensitivity of the model to increases in precipitation and atmospheric humidity is expected to change in applications to coupled models, since these parameters are also strongly implicated, through the representation of clouds, in the simulation of both longwave and shortwave radiation."
"56270311300;7005349646;","Aerosol radiative forcing for Asian continental outflow",2001,"10.1016/S1352-2310(01)00329-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034849234&doi=10.1016%2fS1352-2310%2801%2900329-6&partnerID=40&md5=aec1e4748fddc3af328ee87f3db6c968","Asian aerosols in elevated layers over the Pacific Ocean were sampled with NASA wire-impactors and a FSSP optical particle spectrometer-probe aboard the NASA DC-8 aircraft in early March 1994. Strong variations in aerosol properties, primarily aerosol concentration, lead to derived mid-visible extinctions between 0.003 and 0.5/km. FSSP data usually identified two size-modes. The larger 'coarse mode' (radii of 1-3 μm) was assumed to be dust. The composition of the smaller 'accumulation mode' (radii of 0.1-0.3 μm) was based on the analysis of the wire-impactor samples, as significant amounts of soot reduce mid-visible single scattering albedos to the 0.87-0.92 range. Radiative forcing simulations investigated the impact of Asian outflow aerosol on atmospheric radiative fluxes and heating rates. Only events with larger optical depths were important. In those events the solar attenuation of the smaller size mode dominated the net-flux losses at the surface, with values similar those of urban-polluted and/or biomass burning aerosol types (as observed during the TARFOX and INDOEX field experiments). In contrast, changes to net-fluxes at the top of the atmosphere (ToA) for outflow cases are less negative - primarily due to the added greenhouse effect of the dust component. For the climate of the Earth-Atmosphere-System, ToA net-flux losses are considered a cooling, ToA net-flux gains are associated with warming. Weak cooling is determined for the Asian outflow cases under cloud-free conditions. The addition of a reported 50% cloud cover below the aerosol layer causes a switch to slight warming. © 2001 Elsevier Science Ltd. All rights reserved."
"56630285600;6602580114;6506028787;6506965345;","A case study of the impact of boundary layer aerosol size distribution on the surface UV irradiance",2001,"10.1016/S1352-2310(01)00322-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034854657&doi=10.1016%2fS1352-2310%2801%2900322-3&partnerID=40&md5=68882bed990762aac0bf8eeea907dcdc","The relationship between scattering characteristics of surface aerosol and surface UV irradiance was examined on the basis of the measurements carried out in June-August 1999 in Pärnu, Estonia on the Eastern coast of the Baltic Sea (58°22′27″N, 24°30′43″E). The UV radiation spectra (300-340 nm) were measured with the Ocean Optics Inc. UV spectrometer PC1000, the aerosol size distributions (3-10000 nm) were measured with the electric aerosol spectrometer EAS. A case study was conducted for six sequential cloudless days, when the decrease of the surface UV irradiance was seemingly influenced by atmospheric aerosol. Aerosol radiative properties were calculated from the measured size distributions that represented the maritime polar (North Atlantic) and mixed maritime-continental air. The aerosol optical depths at 500 nm for the North Atlantic air were estimated to be from 0.08 to 0.13. The spectral aerosol optical depth agreed well with the Ångström law, the Ångström exponent α varied from day to day between values of 0.52-0.90. Aerosol asymmetry factor at 300 nm changed between values of 0.76 and 0.80, and was highly correlated with the mean radius of aerosol number distribution. The total aerosol UV scattering was mostly influenced by changes in aerosol with a diameter of 100-560 nm. The aerosol scattering coefficients were positively correlated with the relative humidity of air. The ground aerosol properties were used for calculating the surface UV irradiance from the radiative transfer model of Bird and Riordan (J. Climate Appl. Meteorol. 25 (1986)). The calculated UV irradiances correlated quite well with the measured ones, showing that the use of ground aerosol data for radiative transfer calculations turned out reasonable results. However, ignoring the changes in the aerosol vertical distribution resulted in overestimation of aerosol optical depth on hazy days. © 2001 Elsevier Science Ltd. All rights reserved."
"7407104838;57198966831;6506416205;7405666962;","Indirect sulphate aerosol forcing in a climate model with an interactive sulphur cycle",2001,"10.1029/2000JD000089","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034784017&doi=10.1029%2f2000JD000089&partnerID=40&md5=3e99669789a3efa8a29c186b7317c471","The effects of anthropogenic sulphate aerosol on cloud albedo and on precipitation efficiency (the first and second indirect effects, respectively) are investigated using a new version of the Hadley Centre climate model. This version includes a new cloud microphysics scheme, an interactive sulphur cycle, and a parameterization of the effects of sea salt aerosol. The combined global mean radiative impact from both indirect effects is estimated to be approximately -1.9 W m-2 in terms of the change in net cloud forcing, with the ""albedo"" effect dominating: we obtain values of -1.3 and -0.5 W m-2 for the first and second effects, respectively, when calculated separately. The estimate for the combined effect has at least a factor of 2 uncertainty associated with it: for example, alternative assumptions which affect the, concentration of natural ""background"" sulphate aerosol reduce the forcing by over 25%, and different parameterizations of the autoconversion of cloud droplets to rainwater can double the forcing."
"8333183100;55640270800;7004942632;7102358724;","Updated radiative forcing estimates of 65 halocarbons and nonmethane hydrocarbons",2001,"10.1029/2000JD900716","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034777293&doi=10.1029%2f2000JD900716&partnerID=40&md5=e9e466b3ca46208335b9a622e6a9ee9b","The direct radiative forcing of 65 chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroethers, halons, iodoalkanes, chloroalkanes, bromoalkanes, perfluorocarbons and nonmethane hydrocarbons has been evaluated using a consistent set of infrared absorption cross sections. For the radiative transfer models, both line-by-line and random band model approaches were employed for each gas. The line-by-line model was first validated against measurements taken by the Airborne Research Interferometer Evaluation System (ARIES) of the U.K. Meteorological Office; the computed spectrally integrated radiance of agreed to within 2% with experimental measurements. Three model atmospheres, derived from a three-dimensional climatology, were used in the radiative forcing calculations to more accurately represent hemispheric differences in water vapor, ozone concentrations, and cloud cover. Instantaneous, clear-sky radiative forcing values calculated by the line-by-line and band models were in close agreement. The band model values were subsequently modified to ensure exact agreement with the line-by-line model values. Calibrated band model radiative forcing values, for atmospheric profiles with clouds and using stratospheric adjustment, are reported and compared with previous literature values. Fourteen of the 65 molecules have forcings that differ by more than 15% from those in the World Meteorological Organization [1999] compilation. Eleven of the molecules have not been reported previously. The 65-molecule data set reported here is the most comprehensive and consistent database yet available to evaluate the relative impact of halo carbons and hydrocarbons on climate change. Copyright 2001 by the American Geophysical Union."
"6701346974;7202208382;","A cloud resolving model as a cloud parameterization in the NCAR community climate system model: Preliminary results",2001,"10.1029/2001GL013552","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035883283&doi=10.1029%2f2001GL013552&partnerID=40&md5=b2cc061fdb47596e70e071ad982324a5","Preliminary results of a short climate simulation with a 2-D cloud resolving model (CRM) installed into each grid column of an NCAR Community Climate System Model (CCSM) are presented. The CRM replaces the conventional convective and stratiform cloud parameterizations, and allows for explicit computation of the global cloud fraction distribution for radiation computations. The extreme computational cost of the combined CCSM/CRM model has thus far limited us to a two-month long climate simulation (December-January) using 2.8° × 2.8° resolution. The simulated geographical distributions of the total rainfall, precipitable water, cloud cover, and Earth radiation budget, for the month of January, look very reasonable."
"7409792174;7006095466;","Cumulus ensembles in shear: Implications for parameterization",2001,"10.1175/1520-0469(2001)058<2832:CEISIF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035883235&doi=10.1175%2f1520-0469%282001%29058%3c2832%3aCEISIF%3e2.0.CO%3b2&partnerID=40&md5=33f241e29a1d9fe737920df60ba8f99b","A systematic numerical investigation is conducted into the role of ambient shear on the macrophysical properties of tropical cumulus ensembles maintained by convective available potential energy generated by constant surface fluxes of temperature and moisture and large-scale advective cooling and moistening. The effects of five distinct idealized wind profiles on the organization of convection, and quantities relevant to the parameterization of convection and convectively generated clouds, are examined in a series of 6-day two-dimensional cloud-resolving simulations. Lower-tropospheric shear affects the mesoscale organization of convection through interaction with evaporatively driven downdraft outflows (convective triggering), while shear in mid-to-upper levels determines the amount of stratiform cloud and whether the convective transport of momentum is upgradient or downgradient. Shear significantly affects the convective heating and drying, momentum transport, mass fluxes, and cloud fraction. Sensitivity is strongest in weaker forcing. Cloud-interactive radiation has little direct effect on a 6-day timescale. In particular, the effects of shear on convective momentum transport and cloud fraction are large enough to be potentially significant when included in parameterizations for climate models."
"7103274591;","A new model of the Madden-Julian Oscillation",2001,"10.1175/1520-0469(2001)058<2807:ANMOTM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035883236&doi=10.1175%2f1520-0469%282001%29058%3c2807%3aANMOTM%3e2.0.CO%3b2&partnerID=40&md5=48eeff3324ed2e86e7d377c533f7f19a","A new model of the Madden-Julian oscillation (MJO) is presented. Cloud-radiation interactions in this model make the tropical atmospheres susceptible to large-scale radiative-convective overturning. The modeled MJO takes the form of such an instability, though its behavior is substantially modified by the effects of surface heat flux variability. The dynamics of the disturbance in the model are quasi-balanced, in the sense that the low-level flow in the disturbance is more associated with the vorticity than with the divergence. The cumulus parameterization used in the model allows a lag of several days to exist between the strongest surface heat flux into a column and the development of heavy precipitation in that column. This lag plays a key role in model dynamics."
"6603869642;6603944928;55765625400;","At-site and regional assessment of the possible presence of non-stationary in extreme rainfall in Northern Italy",2001,"10.1016/S1464-1909(01)00073-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034866898&doi=10.1016%2fS1464-1909%2801%2900073-9&partnerID=40&md5=4dbd804ea6f7e3ffa60a27b3ada07e77","The possible presence of non-stationarity in long rainfall records, along with the related consequences in the estimation of the frequency distribution of the extreme events, was recently pointed out in several scientific studies. However, it is well known that the detection of the presence of non-stationarity may be affected by relevant uncertainties, which are mainly originated by the limited length of the available data samples. The present paper describes an analysis aimed at detecting the possible presence of non-stationarity in some long rainfall records observed in northern-central Italy. Firstly a regional analysis is performed in order to assess the possible presence of non-stationarity at regional scale. Secondly synthetic rainfall series are analysed in order to assess how much the sample variability of a short stationary series might induce effects which could be attributed to non-stationarity. © 2001 Elsevier Science Ltd. All rights reserved."
"7203019582;14037939300;55283453700;","Temperature cross-section features in an urban area",2001,"10.1016/S0169-8095(01)00087-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034881599&doi=10.1016%2fS0169-8095%2801%2900087-4&partnerID=40&md5=3504bdda49c43918d7e13c98f4865738","This study examines the connection between the built-up urban surface and near-surface air temperature. The studied city (Szeged, Hungary) is located on a low and flat flood plain with a population of 160,000. Data were collected by mobile measurements under different weather conditions between March 1999 and February 2000. The efforts have been focussed on investigating the maximum development of the urban heat island (UHI) along an urban cross-section. According to the results, the UHI intensity changed according to season and month, as a consequence of the prevailing weather conditions. The role of cloudiness and wind speed on the temporal variation of the largest UHI, which represents the increasing effect of Szeged on temperature, is clearly recognized during most of the time in the studied period. The seasonal profiles follow remarkably well the general cross-section of the typical UHI described by Oke (Oke, T.R., 1987. Boundary Layer Climates. Routledge, London) who defines its characteristic parts as 'cliff', 'plateau' and 'peak'. The usefulness of the normalized values in the investigation is proved, the form of the seasonal mean UHI profile is independent of the seasonal climatological conditions, and is determined to a high degree by urban surface factors. As a conclusion, we suggest a modified model describing the metropolitan temperature variable for cities situated in simple geographical conditions: It is equal to the sum of components of the basic climate of the region and of the production of urbanization at the surface, where this last term is a multiplication of weather and urban surface factors. © 2001 Elsevier Science B.V. All rights reserved."
"15746359800;","NDVI and a simple model of deciduous forest seasonal dynamics",2001,"10.1016/S0304-3800(01)00354-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035442444&doi=10.1016%2fS0304-3800%2801%2900354-4&partnerID=40&md5=8c38422f374557a625614e6b50d9e285","Satellite derived NDVI for forest stands has been related to leaf area index (LAI) (Remote Sens. Environ. 61 (1997) 229), the fraction of absorbed photosynthetically active radiation (fPAR) (Remote Sens. Environ. 58 (1996) 115; Remote Sens. Environ. 61 (1997) 254) and to CO2 uptake (Tellus 43B (1991) 188) with varying success. NDVI observations reflect leaf density, but are primarily indicators of process rates - photosynthesis and transpiration (Int. J. Remote Sens. 7 (1986) 1395). A simple model was developed of seasonal deciduous forest growth as a function of climate variables, including light intensity, temperature and moisture. The model was parameterized for six deciduous Maryland sites with non-photosynthetic biomass between 2.1 and 58.7 kgC/m2. Model estimates of leaf biomass and gross primary productivity were compared to 1992 and 1993 1-km 10-day composite NDVI from the NOAA advanced very high resolution radiometer (AVHRR) instrument. Significant fluctuations in GPP appear to correlate to temporal variations in NDVI. A linear model relating NDVI to leaf biomass and specific gross primary productivity accounted for 51% of the variation in NDVI with P-values for all coefficients &lt; 0.0001. Improvements in field data, more rigorous model treatment of cloud cover, consideration of site heterogeneity and corrections for atmospheric attenuation and satellite view angle might improve the correlation and thus allow use of NDVI for model calibration. © 2001 Elsevier Science B.V. All rights reserved."
"6701342409;6602111828;16687216900;","Bayesian confidence intervals for true fractional coverage from finite transect measurements: Implications for cloud studies from space",2001,"10.1029/2001JD900168","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034838219&doi=10.1029%2f2001JD900168&partnerID=40&md5=f1a7b5b2360c04962ef09954710ad3ac","The general probability distribution for the fractional amount of a geophysical parameter contained within a finite transect has been published previously. On the basis of this information confidence intervals were placed on the observed fraction prior to measurement from knowledge of the underlying distributions for the length of geophysical regions and of the gaps between such regions. In this form, hypothesis testing of models for these length distributions could be made given the observed fraction. However, what is also required (for change detection, for example) is the confidence interval for the true fraction given the observed fraction. Such a reversal of distribution may be provided by Bayes' theorem, as is demonstrated here for the case of underlying exponential distributions for these lengths. As an example, this is applied to transects across cloud fields observed by GMS-5, revealing that confidence intervals for the true cloud fraction, given the observed fraction, can be rather broad over typical climate model grid scales. This is an important result given the current number of proposed satellite-borne missions that are to make transect measurements of cloud parameters, in part to enhance such models. Copyright 2001 by the American Geophysical Union."
"25031430500;7006399667;7003398293;56900249400;35550043200;55947319900;","El Niño as a Natural Experiment for Studying the Tropical Tropopause Region",2001,"10.1175/1520-0442(2001)014<3375:ENOAAN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0003265072&doi=10.1175%2f1520-0442%282001%29014%3c3375%3aENOAAN%3e2.0.CO%3b2&partnerID=40&md5=a30c59d29fd32bc592c0cb2c64b99436","The interannual variability of the tropical tropopause region between 14 and 18 km is examined using observations of convection, winds, and tropopause temperatures from reanalyses and water vapor from satellites. This variability is compared to a simulation using the Community Climate Model version 3 (CCM3) general circulation model forced by observed sea surface temperatures. A coherent picture of the effect of the El Niño-Southern Oscillation (ENSO) on the tropopause region is presented in the NCEP-NCAR reanalyses and CCM3. ENSO modifies convection in the Tropics, and the temperature and circulation of the tropical tropopause region, in agreement with idealized models of tropical heating. CCM3 reproduces most details of these changes, but not the zonal mean temperature variations present in the analysis fields, which are not related to ENSO. ENSO also forces significant changes in observed and simulated water vapor fields. In the upper troposphere water vapor is at maximum near convection, while in the tropopause region water vapor is at minimum in the regions of convection and surrounding it. Convection, cirrus clouds, temperatures, and transport are all linked to describe the water vapor distribution and highlight the role of transport in the tropopause region."
"56271066200;36490968700;7202884070;7410021427;56691869300;55473886300;57207592379;8323763900;7004933306;7005052907;","Real-time national GPS networks for atmospheric sensing",2001,"10.1016/S1364-6826(00)00250-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6644220035&doi=10.1016%2fS1364-6826%2800%2900250-9&partnerID=40&md5=475d5fef0ef6920e00265db7f87d9444","Real-time national global positioning system (GPS) networks are being established in a number of countries for atmospheric sensing. The authors, in collaboration with participating universities, are developing one of these networks in the United States. The proposed network, named ""SuomiNet"" to honor meteorological satellite pioneer Verner Suomi, is funded by the US National Science Foundation to exploit the recently shown ability of ground-based GPS receivers to make thousands of accurate upper and lower atmospheric measurements per day. Phase delays induced in GPS signals by the ionosphere and neutral atmosphere can be measured with high precision simultaneously along a dozen or so GPS ray paths in the field of view. These delays can be converted into integrated water-vapor (if surface pressure data or estimates are available) and total electron content (TEC), along each GPS ray path. The resulting continuous, accurate, all-weather, real-time GPS moisture data will help advance university research in mesoscale modeling and data assimilation, severe weather, precipitation, cloud dynamics, regional climate and hydrology. Similarly, continuous, accurate, all-weather, real-time TEC data have applications in modeling and prediction of severe terrestrial and space weather, detection and forecasting of low-latitude ionospheric scintillation activity and geomagnetic storm effects at ionospheric mid-latitudes, and detection of ionospheric effects induced by a variety of geophysical events. SuomiNet data also have potential applications in coastal meteorology, providing ground truth for satellite radiometry, correction of synthetic aperture radar data for crustal deformation and topography studies, and detection of scintillation associated with atmospheric turbulence in the lower troposphere. In this paper we describe SuomiNet, its applications, and the larger opportunity to coordinate national real-time GPS networks to maximize their scientific and operational impact. © 2001 Published by Elsevier Science Ltd."
"56000281400;7007108728;6603734019;","Ice crystal number concentration versus temperature for climate studies",2001,"10.1002/joc.642","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035419744&doi=10.1002%2fjoc.642&partnerID=40&md5=86cb47f784adef427a56e9594c581fdd","Ice crystal number concentration (Ni) is an important parameter, having a strong influence on the calculation of cloud optical and microphysical parameters. Cloud and precipitation parameterizations within climate and weather forecasting models, affecting the heat and moisture budget of the atmosphere, cannot be determined accurately if Ni is not estimated correctly. Previous studies of ice crystal number concentration versus temperature (T) have shown that Ni-T relationships are not unique. The present study uses observations made in the glaciated regions of stratiform clouds from two Arctic and two mid-latitude field projects to study the Ni versus temperature relationship. Scatter plots of Ni versus T at the ice particle measurement level do not show a good correlation with T for ice crystals at sizes less than 1000 μm. For a given temperature, the variation in Ni is found to be up to two to three orders of magnitude for ice crystals with sizes larger than approximately 100 μm. A significant Ni-T relationship is found for precipitation sized particles with sizes greater than 1000 um. The ice particle concentration for sizes between 100 and 1000 μm varied from 0.1 to 100 L-1, independent of geographic location where the measurements were made. Based on this work, it is concluded that modelling studies should be tested for the possible variations in Ni versus T. Copyright © 2001 Royal Meteorological Society."
"7005171879;7006303509;","A midlatitude cirrus cloud climatology from the facility foratmospheric remote sensing. Part III: Radiative properties",2001,"10.1175/1520-0469(2001)058<2113:AMCCCF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035418617&doi=10.1175%2f1520-0469%282001%29058%3c2113%3aAMCCCF%3e2.0.CO%3b2&partnerID=40&md5=1210ab9c2b763393dc21ce45d32b07be","In Part III of a series of papers describing the extended time high-cloud observations from the University of Utah Facility for Atmospheric Remote Sensing (FARS) supporting the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment, the visible and infrared radiative properties of cirrus clouds over Salt Lake City, Utah, are examined. Using Ο860 h of combined ruby (0.694 μm) lidar and midinfrared (9.5-11.5 μm) radiometer data collected between 1992 and 1999 from visually identified cirrus clouds, the visible optical depths τ and infrared layer emittance ε of the varieties of midlatitude cirrus are characterized. The mean and median values for the cirrus sample are 0.75 ± 0.91 and 0.61 for τ, and 0.30 ± 0.22 and 0.25 for ε. Other scattering parameters studied are the visible extinction and infrared absorption coefficients, and their ratio, and the lidar backscatter-to-extinction ratio, which has a mean value of 0.041 sr-1. Differences among cirrus clouds generated by general synoptic (e.g., jet stream), thunderstorm anvil, and orographic mechanisms are found, reflecting basic cloud microphysical effects. The authors draw parameterizations in terms of midcloud temperature Tm and physical cloud thickness Δz for ε and τ: both macrophysical variables are needed to adequately address the impact of the adiabatic process on ice cloud content, which modulates radiative transfer as a function of temperature. For the total cirrus dataset, the authors find ε = 1 - exp [-8.5 x 10-5 (Tm + 80°C) Δz]. These parameterizations, based on a uniquely comprehensive dataset, hold the potential for improving weather and climate model predictions, and satellite cloud property retrieval methods."
"7005171879;7202652226;","A midlatitude cirrus cloud climatology from the facility foratmospheric remote sensing. Part II: Microphysical properties derived from lidar depolarization",2001,"10.1175/1520-0469(2001)058<2103:AMCCCF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035418224&doi=10.1175%2f1520-0469%282001%29058%3c2103%3aAMCCCF%3e2.0.CO%3b2&partnerID=40&md5=749bb0468d9a0eac059c0be78edf609e","In Part II of this series of papers describing the results of the extended time observations of cirrus clouds from the University of Utah Facility for Atmospheric Remote Sensing (FARS), the information content of laser backscatter depolarization measurements in terms of cloud microphysical content is treated. The authors rely on scattering principles indicating that polarization lidar can be applied to identifying cloud phase, and describing ice particle shape and orientation. It is found that 0.694-μm lidar linear depolarization ratios δ obtained in the zenith display a steady increase with height. With respect to temperature, a minimum of δ = 0.25 is found at -17.5°C, where horizontally oriented planar ice crystals are to be expected, and the δ increase up to 0.45 at -77.5°C. This trend indicates a basic transition in cirrus ice crystals shape with temperature, likely reflecting not only the effects of crystal axis ratio (i.e., plate-to-column) but also internal and radial crystallographic features. Evidence for transient supercooled liquid clouds embedded in cirrus is found at temperatures generally >-20°C. Off-zenith lidar data show that the effects of oriented plate crystals in lowering δ are widespread in cirrus, especially at temperatures >-45°C. Comparisons with other lidar studies are made, and it is concluded that the depolarization data reveal fundamental distinctions in cirrus cloud particle properties that vary with temperature and probably geographical location. It is important to understand such variations in order to improve the ability to model the effects of cirrus clouds on climate."
"6506945155;6603217229;7404463654;7404660540;","MST radar and polarization lindar observations of tropical cirrus",2001,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-5944251014&partnerID=40&md5=64f805afb572d0d014b2d08f35a027eb","Significant gaps in our understanding of global cirrus effects on the climate system involve the role of frequently occurring tropical cirrus. Much of the cirrus in the atmosphere is largely due to frequent cumulus and convective activity in the tropics. In the Indian sub-tropical region, the deep convective activity is very prominent from April to December, which is a favorable period for the formation of deep cumulus clouds. The fibrous anvils of these clouds, laden with ice crystals, are one of the source mechanisms for much of the cirrus in the atmosphere. In the present study, several passages of tropical cirrus were investigated by simultaneously operating MST radar and a co-located polarization lidar at the National MST Radar Facility (NMRF), Gadanki (13.45° N, 79.18° E), India to understand its structure, the background wind field and the microphysics at the cloud boundaries. The lidar system used is capable of measuring the degree of depolarization in the laser backscatter. It has identified several different cirrus structures with a peak linear depolarization ratio (LDR) in the range of 0.1 to 0.32. Simultaneous observations of tropical cirrus by the VHF Doppler radar indicated a clear enhancement of reflectivity detected in the vicinity of the cloud boundaries, as revealed by the lidar and are strongly dependent on observed cloud LDR. An inter-comparison of radar reflectivity observed for vertical and oblique beams reveals that the radar-enhanced reflectivity at the cloud boundaries is also accompanied by significant aspect sensitivity. These observations indicate the presence of anisotropic turbulence at the cloud boundaries. Radar velocity measurements show that boundaries of cirrus are associated with enhanced horizontal winds, significant vertical shear in the horizontal winds and reduced vertical velocity. Therefore, these measurements indicate that a circulation at the cloud boundaries suggest an entrainment taking place close to these levels. The analysis of simultaneous lidar and MST Radar observations can thus yield valuable information on the structure and dynamics of the cirrus, specifically near the boundaries of such clouds."
"7102953444;57202413846;7003630824;24322005900;7004034323;","Evaluation of downward longwave radiation in general circulation models",2001,"10.1175/1520-0442(2001)014<3227:EODLRI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035428622&doi=10.1175%2f1520-0442%282001%29014%3c3227%3aEODLRI%3e2.0.CO%3b2&partnerID=40&md5=fbc919682bf50d3d0aed0ac0970b6999","The longwave radiation emitted by the atmosphere toward the surface [downward longwave radiation (DLR)] is a crucial factor in the exchange of energy between the earth surface and the atmosphere and in the context of radiation-induced climate change. Accurate modeling of this quantity is therefore a fundamental prerequisite for a reliable simulation and projection of the surface climate in coupled general circulation models (GCM). DLR climatologies calculated in a number of GCMs and in a model in assimilation mode (reanalysis) are analyzed using newly available data from 45 worldwide distributed observation sites of the Global Energy Balance Archive (GEBA) and the Baseline Surface Radiation Network (BSRN). It is shown that substantial biases are present in the GCM-calculated DLR climatologies, with the GCMs typically underestimating the DLR (estimated here to be approximately 344 W m-2 globally). The biases are, however, not geographically homogeneous, but depend systematically on the prevailing atmospheric conditions. The DLR is significantly underestimated particularly at observation sites with cold and dry climates and thus little DLR emission. This underestimation gradually diminishes toward sites with more moderate climates: at sites with warm or humid atmospheric conditions and strong DLR emission, the GCM-calculated DLR is in better agreement with the observations or even overestimates them. This is equivalent to creating an excessively strong meridional gradient of DLR in the GCMs. The very same tendencies are independently found in stand-alone calculations with the GCM radiation codes in isolation, using observed atmospheric profiles of temperature and humidity for cloud-free conditions as input to the radiation schemes. A significant underestimation of DLR is calculated by the radiation schemes when driven with clear-sky atmospheric profiles of temperature and humidity representative for cold and dry climates, whereas the DLR is no longer underestimated by the radiation schemes with prescribed clear-sky profiles representative for a hot and humid atmosphere. This suggests that the biases in the GCM-calculated DLR climatologies are predominantly induced by problems in the simulated emission of the cloud-free atmosphere. The same biases are also found in the DLR fluxes calculated by the European Centre for Medium-Range Weather Forecasts (ECMWF) model in assimilation mode (reanalysis), in which the biases in the atmospheric thermal and humidity structure are minimized. This gives further support that the biases in the DLR are not primarily due to errors in the model-predicted atmospheric temperature and humidity profiles that enter the radiative transfer calculations, but rather are due to the radiation schemes themselves. A particular problem in these schemes is the accurate simulation of the thermal emission from the cold, dry, cloud-free atmosphere."
"7005884117;7006846052;","Thermal satellite images and boundary layer structures in desert marginal areas",2001,"10.1029/2000GL006120","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035420089&doi=10.1029%2f2000GL006120&partnerID=40&md5=d48c5e06c960d4344f0ede233a506bc1","A series of parallel striations has been observed on thermal satellite images of a desert marginal area in West Africa. The available climatic data suggest their identification as helical roll vortices of the type associated with the formation of cloud streets. This is because the wavelength of the striations conforms to the expected depth of the Atmospheric Boundary Layer (ABL) expected for such roll structures at the time of the image, and varies spatially according to the influence of ground surface roughness on ABL depth. Knowledge of helical roll vortices is usually derived from vertical temperature and wind profiles and radar reflectivity fields over time, whereas the image data presented here permit visualisation of the horizontal component, and thus examination of their interaction with surface phenomena. Association of the observed striations with systems of stabilised dunes in the study area, due to their similarity in length, direction and spacing, would support hypotheses of a causal relationship between helical roller vortices and linear dune systems."
"7005311892;16637291100;7203059095;57217775956;7501855361;","Spatial and temporal variability of satellite-derived cloud and surface characteristics during FIRE-ACE",2001,"10.1029/2000JD900284","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034875635&doi=10.1029%2f2000JD900284&partnerID=40&md5=aed6744baf83b6196e2bbf9175a0d2a2","Advanced very high resolution radiometer (AVHRR) products calculated for the western Arctic for April-July 1998 are used to investigate spatial, temporal, and regional patterns and variability in energy budget parameters associated with ocean-ice-atmosphere interactions over the Arctic Ocean during the Surface Heat Budget of the Arctic Ocean (SHEBA) project and the First ISCCP (Internatonal Satellite Cloud Climatology Project) Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). The AVHRR-derived parameters include cloud fraction, clear-sky and all-sky skin temperature and broadband albedo, upwelling and downwelling shortwave and longwave radiation, cloud top pressure and temperature, and cloud optical depth. The remotely sensed products generally agree well with field observations at the SHEBA site, which in turn is shown to be representative of a surrounding region comparable in size to a climate-model grid cell. Time series of products for other locations in the western Arctic illustrate the magnitude of spatial variability during the study period and provide spatial and temporal detail useful for studying regional processes. The data illustrate the progression of reduction in cloud cover, albedo decrease, and the considerable heating of the open ocean associated with the anomalous decrease in sea ice cover in the eastern Beaufort Sea that began in late spring. Above-freezing temperatures are also recorded within the ice pack, suggesting warming of the open water areas within the ice cover. Copyright 2001 by the American Geophysical Union."
"57203053317;8419165800;7003430284;7007108728;56000281400;","Simulations of ice clouds during FIRE ACE using the CCCMA single-column model",2001,"10.1029/2000JD900473","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034873103&doi=10.1029%2f2000JD900473&partnerID=40&md5=b6af473be697848e37c55dea2afb4bed","The single-column model (SCM) of the Canadian Centre for Climate Modelling and Analysis (CCCMA) solves prognostic equations for the number concentration and mass mixing ratios of ice crystals. Ice crystal formation is specified via different ice nucleation mechanisms. The CCCMA SCM was used to simulate the evolution of ice clouds for three different flights during the First ISCCP Regional Experiment Arctic Cloud Experiment (FIRE ACE) in April 1998, where measurements of cloud droplets, ice crystals, and aerosols > 0.08 μm in radius were conducted. The CCCMA SCM in its original setup predicts larger ice crystal concentrations than measured with the 2DC probe. The agreement with observations of ice crystals detectable with the 2DC probe was improved if a condensation freezing parameterization depending on supersaturation with respect to ice was used. The best correlation between observed and simulated ice crystal number, which still showed a lot of scatter, was obtained if an empirical linear relationship between the number of aerosols and the number of ice crystals deduced from FIRE ACE was used. Copyright 2001 by the American Geophysical Union."
"7202162685;7102968447;7004353965;7402584913;","Applications of SHEBA/FIRE data to evaluation of snow/ice albedo parameterizations",2001,"10.1029/2000JD900311","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034862967&doi=10.1029%2f2000JD900311&partnerID=40&md5=746439b0ae2db24b37aee01dd1ba535f","Climate models use a wide variety of parameterizations for surface albedos of the ice-covered ocean. These range from simple broadband albedo parameterizations that distinguish among snow-covered and bare ice to more sophisticated parameterizations that include dependence on ice and snow depth, solar zenith angle, and spectral resolution. Several sophisticated parameterizations have also been developed for thermodynamic sea ice models that additionally include dependence on ice and snow age, and melt pond characteristics. Observations obtained in the Arctic Ocean during 1997-1998 in conjunction with the Surface Heat Budget of the Arctic Ocean (SHEBA) and FIRE Arctic Clouds Experiment provide a unique data set against which to evaluate parameterizations of sea ice surface albedo. We apply eight different surface albedo parameterizations to the SHEBA/FIRE data set and evaluate the parameterized albedos against the observed albedos. Results show that these parameterizations yield very different representations of the annual cycle of sea ice albedo. The importance of details and functional relationships of the albedo parameterizations is assessed by incorporating into a single-column sea ice model two different albedo parameterizations, one complex and one simple, that have the same annually averaged surface albedo. The baseline sea ice characteristics and strength of the ice-albedo feedback are compared for the simulations of the different surface albedos. Copyright 2001 by the American Geophysical Union."
"7003567733;36098762900;","Predictions of a simple cloud model for water vapor cloud albedo feedback on Venus",2001,"10.1029/2000JE001266","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034886890&doi=10.1029%2f2000JE001266&partnerID=40&md5=d1fcd9a39d5af01bb491da178f3a0ca4","We developed a simple physical model of Venus' cloud to understand the influence of cloud on the evolution of the surface environment and the climate on Venus. For a given atmospheric structure and composition, the cloud structure and its albedo are calculated through our model. We successfully reproduced the present Venus albedo: the calculated value is 0.87 for 550-nm wavelength, while the observed one is 0.85. The variability of cloud albedo caused by the change of H2O abundance in the Venus atmosphere is examined. Although H2O is merely a minor component of the atmosphere, its influence on the surface environment is found to be quite large. Increase in H2O abundance raises the albedo and cools the surface environment. When H2O abundance is smaller than a critical value of about 0.5 ppmv, complete evaporation of cloud occurs owing to a warming of the atmosphere. When H2O abundance is increased, the H2O abundance in the upper atmosphere is reduced owing to a lower atmospheric temperature produced by high albedo of thick clouds. The cooling of the atmosphere will affect the escape flux of hydrogen from the Venus atmosphere into space. Copyright 2001 by the American Geophysical Union."
"7405728922;6603400519;35446498700;","Direct radiative forcing and atmospheric absorption by boundary layer aerosols in the southeastern US: Model estimates on the basis of new observations",2001,"10.1016/S1352-2310(01)00187-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034972453&doi=10.1016%2fS1352-2310%2801%2900187-X&partnerID=40&md5=19ca1444def7678d791b4533766ce573","In an effort to reduce uncertainties in the quantification of aerosol direct radiative forcing (ADRF) in the southeastern United States (US), a field column experiment was conducted to measure aerosol radiative properties and effects at Mt. Mitchell, North Carolina, and at an adjacent valley site. The experimental period was from June 1995 to mid-December 1995. The aerosol optical properties (single scattering albedo and asymmetry factor) needed to compute ADRF were obtained on the basis of a procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, aerosol optical depth, and diffuse-to-direct solar irradiance ratio. The regional values of ADRF at the surface and top of atmosphere (TOA), and atmospheric aerosol absorption are derived using the obtained aerosol optical properties as inputs to the column radiation model (CRM) of the community climate model (CCM3). The cloud-free instantaneous TOA ADRFs for highly polluted (HP), marine (M) and continental (C) air masses range from 20.3 to -24.8, 1.3 to -10.4, and 1.9 to -13.4Wm-2, respectively. The mean cloud-free 24-h ADRFs at the TOA (at the surface) for HP, M, and C air masses are estimated to be -8±4 (-33±16), -7±4 (-13±8), and -0.14±0.05 (-8±3) Wm-2, respectively. On the assumption that the fractional coverage of clouds is 0.61, the annual mean ADRFs at the TOA and the surface are -2±1, and -7±2Wm-2, respectively. This also implies that aerosols currently heat the atmosphere over the southeastern US by 5±3Wm-2 on annual timescales due to the aerosol absorption in the troposphere. Copyright © 2001 Elsevier Science Ltd."
"7403401100;35461763400;7405551904;7004864963;","Cloud condensation nuclei in the Amazon Basin: ""Marine"" conditions over a continent?",2001,"10.1029/2000GL012585","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035878313&doi=10.1029%2f2000GL012585&partnerID=40&md5=cba408ed70dfa62c3dab670d399708a6","Cloud condensation nuclei (CCN) are linked to radiative forcing, precipitation, and cloud structure; yet, their role in tropical climates remains largely unknown. CCN concentrations (NCCN) measured during the wet season in the Amazon Basin were surprisingly low (mean NCCN at 1% supersaturation: 267 ± 132 cm-3) and resembled concentrations more typical of marine locations than most continental sites. At low background CCN concentrations, cloud properties are more sensitive to an increase in NCCN. Therefore, enhanced aerosol emissions due to human activity in the Amazon Basin may have a stronger impact on climate than emissions in other continental regions. In spite of the large organic fraction in the Amazonian aerosol, a detailed analysis of number distributions and size-dependent chemical composition indicates that sulfate plays an important role in CCN activity."
"6507163086;7005070958;","Cloud cover variations over the United States: An influence of cosmic rays or solar variability?",2001,"10.1029/2000GL012659","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035391035&doi=10.1029%2f2000GL012659&partnerID=40&md5=dede5899ef54e510289a1da35dadacc2","To investigate whether galactic cosmic rays (GCR) may influence cloud cover variations, we analyze cloud cover anomalies from 1900-1987 over the United States. Results of spectral analyses reveal a statistically significant cloud cover signal at the period of 11 years; the coherence between cloud cover and solar variability proxy is 0.7 and statistically significant with 95% confidence. In addition, cloud data derived from the NCAR Climate System Model (CSM) forced with solar irradiance variations show a strong signal at 11 years that is not apparent in cloud data from runs with constant solar input. The cloud cover variations are in phase with the solar cycle and not the GCR. Our results suggest that cloud variabilities may be affected by a modulation of the atmospheric circulation resulting from variations of the solar-UV-ozone-induced heating of the atmosphere."
"6603669021;7003371535;","Parametrization of solar radiation in inhomogeneous stratocumulus: Albedo bias",2001,"10.1256/smsqj.57506","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035390283&doi=10.1256%2fsmsqj.57506&partnerID=40&md5=4c844936afe78fda04a1d58e003e454e","Low-level cloud fields with typical albedos between 50% and 70% contribute significantly to short-wave cloud radiative forcing. Consequently, the earth's radiative budget is sensitive to extended stratocumulus which typically occurs in sub-tropical subsidence regions over the oceans. It is therefore vital to represent the cloud albedo of such cloud fields accurately in climate models. Nevertheless, cloud fields are modelled as homogeneous plane-parallel clouds, which leads to an overestimation of the albedo by up to 15% compared with real inhomogeneous clouds, both types of cloud fields having the same mean cloud optical depth. This so-called plane-parallel cloud albedo bias has given rise to a number of studies that present methods for reducing the albedo bias for stratiform clouds in climate models. Using Monte Carlo simulations and the Independent Pixel Approximation (IPA) the inhomogeneous cloud albedo is investigated with the aim of deriving a parametrization of the albedo bias. The new approach used here is that the variance of the cloud optical depth is parametrized as a function of grid size and mean cloud liquid-water content. The variance of the cloud optical depth is derived from turbulence processes. For the determination of the albedo bias an analytical solution is presented which is based on a simplified distribution function of the cloud optical depth and the IPA method. When used in conjunction with the parametrized variance of the cloud optical depth, a box function, which replaces the distribution function, produces comparable results to Monte Carlo simulations within an acceptable accuracy of a few per cent."
"7102663296;7203073478;","Retrieval of microphysical and morphological properties of volcanic ash plumes from satellite data: Application to Mt Ruapehu, New Zealand",2001,"10.1256/smsqj.57614","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035386943&doi=10.1256%2fsmsqj.57614&partnerID=40&md5=2da264f8acd5ca584547d0f454b78382","A quantitative analysis of the properties of several Mt Ruapehu, New Zealand, ash plumes has been performed using multispectral satellite data from the AVHRR-2 and ATSR-2 instruments. The analysis includes: identification of the plume from background clouds using the 'reverse' absorption effect in the thermal channels; modelling and retrieval of particle sizes; determination of the plume height from cloud shadows, stereoscopy and meteorological data: and estimates of the mass of fine particles (radii less than 10 μm). A new spectral technique for identifying opaque, silica-rich ash clouds is demonstrated by utilizing the near-infrared (1.6μm) and visible (0.67 μm) channels of the ATSR-2, and the optical properties of a simple volcanic cloud are presented for use in radiative transfer studies. It is found that the Ruapehu eruption cloud contained silica-rich ash particles with radii generally less than a few micrometres. The distribution of fine particles is monomodal with a dominant mode peak of about 3 μm radius. Mass loadings of fine particles are found to be in the range ≈ 1 to ≈ 7 mg m-3, and are consistent with estimates of mass loadings of volcanic clouds from eruptions of other volcanoes. The height of the plume top, derived from radiosonde data and plume-top temperatures in the opaque regions, was found to be between 7.5 and 8.5 km, while the plume thickness was estimated to be between 1.5 and 3 km. Cloud height derived from ATSR-2 stereoscopy on a different plume gave heights in the range 5 to 8 km. The results of this study provide important information on the optical properties of nascent volcanic eruption plumes. This information may prove useful in determining the potential effects of volcanic clouds on local climate, and in assessing any hazard to aviation."
"7005561047;","Possible bounds on the earth's surface temperature: From the perspective of a conceptual global-mean model",2001,"10.1175/1520-0442(2001)014<2976:PBOTES>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035385343&doi=10.1175%2f1520-0442%282001%29014%3c2976%3aPBOTES%3e2.0.CO%3b2&partnerID=40&md5=76510adc07cf5841cdad2a1bd49026c0","A global-mean model is used here to elucidate possible bounds on the surface temperature of a simplified ocean-atmosphere system. Extending previous one-dimensional models, it has included as internal variables the low-level and high-level cloud covers and the turbulent wind at the surface. The main hypothesis for the model closure is that the conversion rate from the solar to the kinetic energy-or, equivalently, the rate of internal entropy production-is maximized, which has been applied with considerable success in past latitudinal models. From the model derivation, it is found that the surface temperature is narrowly bounded below by the onset of the greenhouse effect and above by the rapid increase of the saturation vapor pressure. Because both are largely intrinsic properties of water, the resulting surface temperature is mostly insensitive to detailed balances or changing external conditions. Even with a 50% change of the solar constant from its present-day value, the model temperature has varied by only about 10 K. The reason that the heat balances can be maintained is an internal adjustment of the low cloud cover, which offsets the solar effect. The model offers a plausible explanation of an equable climate in the geological past so long as there is a substantial ocean."
"6603809220;7102604282;","Indirect aerosol forcing, quasi forcing, and climate response",2001,"10.1175/1520-0442(2001)014<2960:IAFQFA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035385327&doi=10.1175%2f1520-0442%282001%29014%3c2960%3aIAFQFA%3e2.0.CO%3b2&partnerID=40&md5=ed6c12e30a42fd44816756b9c332d0a2","The component of the indirect aerosol effect related to changes in precipitation efficiency (the second indirect or Albrecht effect) is presently evaluated in climate models by taking the difference in net irradiance between a present-day and a preindustrial simulation using fixed sea surface temperatures (SSTs). This approach gives a ""quasi forcing,"" which differs from a pure forcing in that fields other than the initially perturbed quantity have been allowed to vary. It is routinely used because, in contrast to the first indirect (Twomey) effect, there is no straightforward method of calculating a pure forcing for the second indirect effect. This raises the question of whether evaluation of the second indirect effect in this manner is adequate as an indication of the likely effect of this perturbation on the global-mean surface temperature. An atmospheric global climate model (AGCM) is used to compare the evaluation of different radiative perturbations as both pure forcings (when available) and quasi forcings. Direct and indirect sulfate aerosol effects and a doubling of carbon dioxide (CO2) are considered. For evaluation of the forcings and quasi forcings, the AGCM is run with prescribed SSTs. For evaluation of the equilibrium response to each perturbation, the AGCM is coupled to a mixed layer ocean model. For the global-mean direct and first indirect effects, quasi forcings differ by less than 10% from the corresponding pure forcing. This suggests that any feedbacks contaminating these quasi forcings are small in the global mean. Further, the quasi forcings for the first and second indirect effects are almost identical when based on net irradiance or on cloud-radiative forcing, showing that clear-sky feedbacks are negligible in the global mean. The climate sensitivity parameters obtained for the first and second indirect effects (evaluated as quasi forcings) are almost identical, at 0.78 and 0.79 K m2 W-1, respectively. Climate sensitivity parameters based on pure forcings are 0.69, 0.84, and 1.01 K m2 W-1 for direct sulfate, first indirect, and 2 X CO2 forcings, respectively. The differences are related to the efficiency with which each forcing excites the strong surface-albedo feedback at high latitudes. Closer examination of the calculations of the first indirect effect as a forcing and quasi forcing shows that, although they are in reasonable agreement in the global mean, there are some significant differences in a few regions. Overall, these results suggest that evaluation of the globally averaged second indirect effect as a quasi forcing is satisfactory."
"7405459515;6701797646;6701464149;7006783796;24611027600;","A further study of the method for estimation of SAGE II opaque cloud occurrence",2001,"10.1029/2001JD900138","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034914415&doi=10.1029%2f2001JD900138&partnerID=40&md5=01e716b5fece371a13e86077e7a8b073","Information on vertical cloud distribution is important to atmospheric radiative calculation, general circulation modeling, and climate study. The method used for estimating the vertical structure of opaque cloud occurrence from the solar occultation observations obtained by the Stratospheric Aerosol and Gas Experiment (SAGE) II has been reviewed for further understanding of the nature of the derived cloud statistics. Most importantly, based on the SAGE II tropical observations (1985-1998), the present study illustrates that the derived opaque cloud occurrence at a given altitude is generally independent of the cloud occurrence at other altitudes, except for some anticorrelation between high-level (12.5 km) and low-level (1-3 km) clouds. This feature of the layer cloud frequency independence is also evident when regional data over the Pacific warm pool and the eastern Pacific are examined. The independ-ent information of the layer cloud frequency is significant and makes it possible to use the derived vertical distribution of cloud occurrence to estimate the probability of multilayer clouds. The limitation is that it is difficult to determine how frequently the multilayer clouds are actually overlapping or how frequently thick cloud (> 1 km) really occurs based on the SAGE II observations alone. A discussion of the SAGE II tropical opaque cloud occurrence in relation to the cloud climatology based on visual observations from surface stations and ships, the International Satellite Cloud Climatology Project data, and the cloud statistics using rawinsonde records is also provided. Copyright 2001 by the American Geophysical Union."
"7405367162;7005070958;","Algorithm development strategies for retrieving the downwelling longwave flux at the Earth's surface",2001,"10.1029/2001JD900144","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034923262&doi=10.1029%2f2001JD900144&partnerID=40&md5=74eb920d05d8bca7c378ae658fe79598","Algorithm development strategies for retrieving the surface downwelling longwave flux (SDLW) have been formulated on the basis of detailed studies with radiative transfer models and observational data. The model sensitivity studies were conducted with the column radiation model from the National Center for Atmospheric Research Community Climate Model Version 3 and the Moderate-Resolution Transmittance radiation model. The studies show the clear-sky SDLW can be largely determined from only two parameters: the surface upwelling longwave flux and the column precipitable water vapor. Cloudy-sky sensitivity tests show that, as would be expected, cloud base height is an important factor in determining the SDLW, especially for low clouds. However, when considering broken clouds as occur in reality, there is no way of logically defining an average cloud base height. Instead, cloud liquid water path is shown to be a preferable parameter for use in an all-sky algorithm, not because it serves as a direct cloud input parameter, but rather that it serves as a useful surrogate for cloud base height. Observational data from the Atmospheric Radiation Measurements Program at the U.S. Southern Great Plains (SGP) Oklahoma Central Facility and the Tropical Western Pacific (TWP) Manus Island were used in deriving and validating an illustrative algorithm. The observations show similar relations as found in the model sensitivity tests and suggest that a single algorithm could be applicable for both clear and cloudy conditions as well as for diverse geographical locations. For example, when applied to the TWP data, an algorithm based on a regression of SGP all-sky data produces a relative bias error in SDLW of only 1.4% under all-sky conditions and -0.2% for clear skies. Copyright 2001 by the American Geophysical Union."
"6603745250;","Influence of climate variability on the atmospheric transport of Icelandic tephra in the subpolar North Atlantic",2001,"10.1016/S0921-8181(01)00099-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034976068&doi=10.1016%2fS0921-8181%2801%2900099-6&partnerID=40&md5=7550213fac85e7f4faf6f391a8ec9f77","Atmospheric transport of Icelandic tephra has been simulated using data on atmospheric circulation and a theoretical model of tephra fallout. Two major features control the trajectories of tephra from Iceland: (1) persistent westerlies in the lower stratosphere between 9 and 15 km; and (2) a seasonal shift in wind direction above about 15 km that becomes more significant at higher elevations, with strong westerlies during the fall and winter, and relatively weak easterlies during the spring and summer. Model-derived predictions of the distance traveled by Icelandic tephra as a function of particle size have been made for each season, and for eruption columns ranging from 10- to 50-km height. The downwind decrease in grain size appears to be less significant as the eruption cloud rises to higher altitudes where stronger winds prevail. Predictions for fall and winter agree well with observations of historical and post-glacial tephra falls in western Europe, and provide a rough estimate of the height of the related eruption columns. Predictions for spring and summer dispersal may explain why the Greenland ice sheet is relatively barren of tephra fall from Iceland, due to weak stratospheric easterlies. Grain size of submarine tephra fall deposits in the Iceland Basin and on the Iceland Plateau indicates, however, that the present atmospheric circulation may not account for tephra transport during the Pliocene and Pleistocene. The coarser grain size of these older deposits may be related to enhanced atmospheric circulation in the subpolar North Atlantic during these epochs or higher eruption columns due to more powerful eruptions in Iceland. © 2001 Elsevier Science B.V."
"6602098362;7403968239;","Radiative sensitivity to water vapor under all-sky conditions",2001,"10.1175/1520-0442(2001)014<2798:RSTWVU>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035874658&doi=10.1175%2f1520-0442%282001%29014%3c2798%3aRSTWVU%3e2.0.CO%3b2&partnerID=40&md5=3ec3cbc4b985aefa94fe0993d2a6b390","Using the National Center for Atmospheric Research Community Climate Model, version 3, radiation transfer model and a realistic tropospheric environment including the International Satellite Cloud Climatology Project cloud fields, all-sky radiative sensitivity to water vapor is assessed. The analysis improves upon previous clear-sky and model-based studies by using observed clouds, assessing realistic vertically varying perturbations, and considering spatial gradients in sensitivity through the Tropics and subtropics. The linearity of sensitivity is also explored. The dry zones of the subtropics and the eastern Pacific Ocean are found to be particularly sensitive to the water vapor distribution, especially for variations in the upper troposphere. The cloud field is instrumental in determining spatial gradients in sensitivity both at the top of the atmosphere and the surface. Throughout the Tropics, outgoing longwave radiation is most sensitive to water vapor in the upper troposphere, especially when perturbations characteristic of either natural variations or measurement uncertainties are considered. In contrast, surface radiative fluxes are everywhere most sensitive to specific humidity variations in the lower troposphere."
"7404142321;7004764167;7406514318;","Transient climate change in the Hadley Centre models: The role of physical processes",2001,"10.1175/1520-0442(2001)014<2659:TCCITH>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035874663&doi=10.1175%2f1520-0442%282001%29014%3c2659%3aTCCITH%3e2.0.CO%3b2&partnerID=40&md5=ee495f88d562fe3d619ac18a3c68fefe","A comparison of the response to increasing greenhouse gas concentrations of two versions of the Met Office's (Hadley Centre) coupled atmosphere-ocean model reveals differences that result in large local variations in the modeled impact of climate change. With the aim of understanding the important processes and feedbacks associated with climate change, and ultimately reducing uncertainty in predictions, a series of sensitivity experiments were performed using a coupled atmosphere-mixed layer ocean model. The primary differences in the atmospheric response of the coupled models studied are found to be due to changes made to the physical representation of the atmosphere rather than to the ocean. In particular, many of the different patterns of response can be explained through changes made to the boundary layer scheme combining in a nonlinear way with changes to the cloud scheme to alter the tropical temperature and precipitation response in the model. A new land surface exchange scheme largely accounts for the different Northern Hemisphere continental surface temperature response."
"7005310521;7202671706;","North Atlantic climate variability in early Palaeogene time: A climate modelling sensitivity study",2001,"10.1144/GSL.SP.2001.183.01.12","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035019720&doi=10.1144%2fGSL.SP.2001.183.01.12&partnerID=40&md5=d70caa8b647d12eb5333e8070e9e96b9","Understanding the nature and causes of the variability associated with past warm, high pCO2 climates presents a significant challenge to palaeoclimate research. In this paper we investigate the early Eocene climatic response in the North Atlantic region to forcing from an indirect effect of atmospheric methane (via polar stratospheric clouds (PSCs), and we investigate the response of the climate system to forcing from a combination of orbital insolation changes and high atmospheric pCO2 concentration. We find that sea surface temperatures (SSTs), sea ice extent, net surface moisture, continental runoff and upwelling in the North Atlantic Ocean are all sensitive to those forcing factors, and that the degree of sensitivity is a function of location and season. Our results suggest that high-latitude SST values can vary by as much as 20 °C during the winter season in response to precessional and polar cloud forcing, whereas in contrast summer temperature varies by 4 °C or less. Model predictions of net surface moisture balance also vary substantially with our prescribed forcing. There is a large difference in variability between the localized net surface moisture results and the mean North Atlantic Ocean results, which suggests that large-scale assumptions about past surface ocean salinities and seawater δ18O may need to be reassessed. According to model results, the influx of terrigenous material via continental runoff to the North Atlantic Ocean should be highly seasonal, with greatest runoff occurring in spring. Our model results also indicate that changes in wind-driven upwelling and in continental runoff on a precessional time scale should be seen in regions of the central North Atlantic."
"55637266800;","The role of water vapour in the atmosphere. A short overviewfrom a climate modeller's point of view",2001,"10.1016/S1464-1895(01)00094-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035020247&doi=10.1016%2fS1464-1895%2801%2900094-1&partnerID=40&md5=9beefe40e7e8f236f3832d322fa61f8b","Water vapour plays a dominant role in the radiative balance and the hydrological cycle. It is a principal element in the thermodynamics of the atmosphere, it transports latent heat, it contributes to absorption and emission in a number of bands and it condenses into clouds that reflect and absorb solar radiation, thus directly affecting the energy balance. In the lower atmosphere, the water vapour concentrations can vary by orders of magnitude from place to place. This variability creates a fundamental problem in climate modelling due to the very high temporal and spatial resolution needed to resolve all processes creating the sharp gradients which are related to the variability. The contribution of water vapour to atmospheric phenomena on different time and space scales for today's and future climates are discussed as well as the importance of water vapour monitoring. The latter is a prerequisite for model validation and an important contribution to the understanding of the behaviour of the atmosphere. It is shown that only the validation of more than one component of the hydrological cycle leads to a better understanding and an improvement of the simulations. © 2001 Elsevier Science Ltd. All rights reserved."
"25227357000;7102018821;","Radiation parameterization for three-dimensional inhomogeneous cirrus clouds: Application to climate models",2001,"10.1175/1520-0442(2001)014<2443:RPFTDI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035354693&doi=10.1175%2f1520-0442%282001%29014%3c2443%3aRPFTDI%3e2.0.CO%3b2&partnerID=40&md5=1be62d5c7ba3baf45d6518e594426a0b","A three-dimensional (3D) radiative transfer model has been developed to simulate the transfer of solar and thermal infrared radiation in inhomogeneous cirrus clouds. The model utilizes a diffusion approximation approach (four-term expansion in the intensity) for application to inhomogeneous media, employing Cartesian coordinates. The extinction coefficient, single-scattering albedo, and asymmetry factor are functions of spatial position and wavelength and are parameterized in terms of the ice water content and mean effective ice crystal size. The correlated k-distribution method is employed for incorporation of gaseous absorption in multiple-scattering atmospheres. Delta-function adjustment is used to account for the strong forward-diffraction nature in the phase function of ice particles to enhance computational accuracy. Comparisons of the model results with those from plane-parallel (PP) and other 3D models show reasonable agreement for both broadband and monochromatic results. Three-dimensional flux and heating/cooling rate fields are presented for a number of cirrus cases in which the ice water content and ice crystal size are prescribed. The PP method is shown to be a good approximation under the homogeneous condition when the cloud horizontal dimension is much larger than the cloud thickness. As the horizontal dimension decreases, clouds produce less infrared warming at the bottom as well as less cooling at the top, while more solar heating is generated within the cloud. For inhomogeneous cases, upwelling and downwelling fluxes display patterns corresponding to the extinction coefficient field. Cloud inhomogeneity also plays an important role in determining both solar and IR heating rate distributions. The radiation parameterization is applied to potential cloud configurations generated from GCMs to investigate broken clouds and cloud-overlapping effects on the domain-averaged heating rates. Clouds with maximum overlap tend to produce less heating than those with random overlap. For the prescribed cloud configurations designed in this paper, broken clouds show more solar heating as well as more IR cooling as compared with a continuous cloud field."
"8654071800;57205980737;24438914900;","Modelling historical lake levels and recent climate change at three closed lakes, Western Victoria, Australia (c.1840-1990)",2001,"10.1016/S0022-1694(01)00369-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035370239&doi=10.1016%2fS0022-1694%2801%2900369-9&partnerID=40&md5=5b5c43620941ea3d8dce3d20ca290dfb","Lake levels of three hydrologically closed maar lakes, Lakes Keilambete, Gnotuk and Bullenmerri in Western Victoria, Australia, have declined since the first recorded observations in 1841. High levels were previously sustained for several centuries with the lakes in climatic equilibrium. Historical survey and field investigations provide a detailed picture of both historical land-use changes and of the geological and hydrogeological influences on the water budget. Groundwater components include baseflow from deep percolation within the catchment and discharge from a surrounding low-yield aquifer. A perched watertable at Lake Keilambete helped maintain high lake levels. Climate records back to 1859 Were reconstructed; inhomogeneities from 1863 were removed creating a high quality instrumental record. A water balance model simulating the historical decline demonstrates important features. (1) Regional climate expressed as a lake precipitation/evaporation (P/E) ratio remains the over-riding influence on lake levels. (2) The lakes fell in response to a change in climate. (3) This climate change pre-dated instrumental records. (4) Land-use change did not contribute to declining water levels. The fall in water levels was initiated by a decrease in P/E ratio from a pre- 1840 value of 0.94-0.96 to a historical value of 0.79, This change probably involved a decrease in rainfall, possibly associated with increases in solar radiation and decreases in cloud cover. Temperature (T) may also have increased but the likelihood of an altered temperature-evaporation relationship means that a quantified estimate is not possible. The ability of the lakes to reflect climate independently of land-use change is highly unusual, both in Australia and elsewhere. These lakes provide a rare opportunity to discriminate between human impact on regional hydrology and climate change. © 2001 Elsevier Science B.V."
"7003908632;27267529400;","Microphysical parameterization of Arctic diamond dust, ice fog and thin stratus for climate models",2001,"10.1175/1520-0469(2001)058<1181:MPOADD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035872731&doi=10.1175%2f1520-0469%282001%29058%3c1181%3aMPOADD%3e2.0.CO%3b2&partnerID=40&md5=b2b0c0cc5f25215d081fbb2880cf7008","A parameterization is described for low-level clouds that are characteristic of the Arctic during winter. This parameterization simulates the activation of aerosols, the aggregation/coalescence, and the gravitational deposition of ice crystals/water droplets and the deposition/condensation of water vapor onto ice crystals/water droplets. The microphysics scheme uses four prognostic variables to characterize clouds: Ice water content, liquid water content, and the mean diameter for ice crystals and for water droplets, and includes prognostic supersaturation. The parameterization simulates stable clouds where turbulence and entrainment are weak, like ice fogs, thin stratus, and diamond dust. The parameterization is tested into the Local Climate Model (LCM), which is the single column version of the Northern Aerosol Regional Climate Model (NARCM). NARCM is a regional model with an explicit representation of the aerosol physics and with the physics package of the Canadian Climate Center General Circulation Model version two. Since most climate models do not have prognostic size-segregated aerosol representation, an alternate method is proposed to implement the microphysical parameterization into these models. The model results are compared to observations of diamond dust and ice fog at Alert (Canada) for the period 1991-94. Two aerosol scenarios are compared in the simulation: A natural background aerosol scenario and an acidic aerosol scenario. Results show that the LCM reproduces approximately the time variation of the observed weekly frequency of the total ice crystal precipitation with a correlation coefficient of 0.4. Although it overestimates diamond dust frequency and underestimates ice fog frequency, the LCM predicts quite well the total precipitation frequency (ice fog and diamond dust added). The acidic aerosol scenario is in good agreement with the observations, showing a mean frequency of total precipitation over the 4 yr of 39% compared to the observed value of 37%. The natural aerosol scenario overestimates this frequency with a value of 47%. These results were expected since recent aerosol observations have shown the predominance of sulfuric acid-coated aerosols in the Arctic during winter."
"7003908632;27267529400;","Simulation of Arctic diamond dust, ice fog, and thin stratus using an explicit aerosol-cloud-radiation model",2001,"10.1175/1520-0469(2001)058<1199:SOADDI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035872740&doi=10.1175%2f1520-0469%282001%29058%3c1199%3aSOADDI%3e2.0.CO%3b2&partnerID=40&md5=c5fae74f2370a89984fa40838ebfb3ce","In support to the development of the Northern Aerosol Regional Climate Model, a single column model with explicit aerosol and cloud microphysics is described. It is designed specifically to investigate cloud-aerosol interactions in the Arctic. A total of 38 size bins discretize the aerosol and cloud spectra from 0.01 - to 500-μm diameter. The model is based on three equations describing the time evolution of the aerosol, cloud droplet, and ice crystal spectra. The following physical processes are simulated: Coagulation, sedimentation, nucleation, coalescence, aggregation, condensation, and deposition. Further, the model accounts for the water-ice phase interaction through the homogeneous and heterogeneous freezing, ice nuclei, and the Bergeron effect. The model has been validated against observations and other models. In this paper, the model is used to simulate diamond dust and ice fog in the Arctic during winter. It is shown that simulated cloud features such as cloud phase, cloud particle diameter, number concentration, and mass concentration are in agreement with observations. The observed vertical structure of mixed-phase cloud is also reproduced with the maximum mass of liquid phase in the upper part of the cloud. Based on simulations, a hypothesis is formulated to explain the thermodynamical unstable mixed-phase state that can last several days in diamond dust events. The ice supersaturation time evolution is assessed and is compared to its evolution in cirrus clouds. It is shown that the supersaturation relaxation time, defined as the time required for supersaturation to decrease by a factor e. is more than 10 times the value found in cirrus clouds. Finally, the radiative contribution of arctic diamond dust and ice fog to the downward longwave radiation flux at the surface is evaluated and compared to observations."
"7402346120;","Boundary layer roll statistics from SAR",2001,"10.1029/2000GL012667","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035874437&doi=10.1029%2f2000GL012667&partnerID=40&md5=858f76c0fea965b423068f24b9f680cf","The Atmospheric Boundary Layer (ABL) mean flow frequently consists of an organized secondary circulation in the form of counter rotating rolls embedded in it. Theory predicts this is the case for a range of thermodynamic conditions. Although generally associated with the formation of ""cloud streets"", numerical and theoretical studies suggest that rolls should be present whenever there is sufficient shear to organize the convection, including cloud free conditions. Through their association with clouds and their modification of the mean low level flow, ABL rolls alter air-sea interaction processes, surface energy fluxes, and the earth radiational balance. Despite their potential importance to climate there exist no prior studies that can establish the extent and statistical frequency of roll occurrence. Synthetic Aperture Radar (SAR) can detect ABL roll signature on the ocean surface. A first regional climate scale attempt to construct ABL roll frequency statistics from the RADARSAT SAR observations is described."
"7004014731;56228733900;","Synoptic mapping of convective structure from undersampled satelite observations",2001,"10.1175/1520-0442(2001)014<2281:SMOCSF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035872229&doi=10.1175%2f1520-0442%282001%29014%3c2281%3aSMOCSF%3e2.0.CO%3b2&partnerID=40&md5=1bdd41476179f94d54549bb6442ee192","Climate properties regulated by convection, such as water vapor, cloud cover, and related distributions, are undersampled in asynoptic data from an individual orbiting platform, which must therefore be restricted to time-mean distributions. A procedure is developed to identify small-scale undersampled variance in asynoptic data and reject it, leaving a more accurate representation of large-scale variance that describes the organization of climate properties. The procedure is validated against high-resolution distributions that have been constructed from six satellites simultaneously observing the earth. Observing the high-resolution distributions asynoptically is shown to result in sampling error at large scales that is as great as the large-scale signal present, limiting the usefulness of the raw asynoptic data to time-mean distributions. However, processing the asynoptic data to reject undersampled incoherent variability reduces the error variance to 10% or less, yielding a fairly accurate representation of large-scale coherent variability, which then can be mapped synoptically on periods as short as 2.0 days. Made possible then are studies of how cloud, water vapor, and related distributions are organized by unsteady elements of the general circulation, which cannot be studied in the raw asynoptic data."
"56962915800;7402205043;","Processes determining the rapid reestablishment of the Equatorial Pacific Cold Tongue/ITCZ complex",2001,"10.1175/1520-0442(2001)014<0001:PDTRRO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035872225&doi=10.1175%2f1520-0442%282001%29014%3c0001%3aPDTRRO%3e2.0.CO%3b2&partnerID=40&md5=b7ca70a258bba2cb9b25d9ef65ed119f","The annual reestablishment of the equatorial cold tongue (ECT) in the Pacific is signified by a remarkably rapid reversal of the warming trend from March to May. The processes responsible for this dramatic turnabout are investigated using the outputs generated by a coupled ocean-atmosphere model, which simulates realistic tropical Pacific climate. A new diagnostic equation is put forward for a budget study of the temperature tendency in a mixed layer (ML) with a variable depth. The budget study reveals that the rapid boreal spring cooling in the ML of the ECT (4°S-2°N, 120°-90°W) is primarily attributed to turbulent entrainment (54%), surface evaporation (21%), and meridional advection (14%). The spring shallowness of the ML is also a significant ""implicit"" contributor. Annually, the ML depth in the ECT varies nearly 180° out of phase with the SST while in phase with the ML heat content. The annual variation of the ML depth is determined by competing effects of the Ekman transport and turbulent entrainment. From March to July, the increase of the meridional wind component dominates that of the zonal component; thereby, the effect of entrainment surpasses that of upwelling, leading to mixed layer deepening. The mechanism governing the annual variation of the ML heat content is essentially the same as those governing the ML depth variation. The results suggest that accurate modeling of the ML turbulent mixing holds the key to realistic simulation of the annual cycle of the ECT. In contrast, beneath the ITCZ (8°-12°N, 100°-120°W), the rapid spring warming is attributable to increased surface heat flux, while entrainment and thermal advection play minor roles. From February to May, the downward shortwave radiation and the surface latent heat fluxes, along with concurrent equatorial cooling, result in a northward progression of the annual warming and promote an active ITCZ-ECT interaction (including evaporation-wind feedback and cloud-radiation-SST interaction)."
"55887849100;7201551011;","Sunshine records from Ireland: Cloud factors and possible links to solar activity and cosmic rays",2001,"10.1002/joc.657","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035334276&doi=10.1002%2fjoc.657&partnerID=40&md5=2366ebec2d00d9d618c3f15ca8dfaee3","The records of sunshine hours obtained since the late 19th century from four stations distributed throughout Ireland were analysed. A gradual decrease in sunshine hours has occurred at all four sites since records began. Increasing cloud factors, resulting from enhanced evaporation rates over the Atlantic as sea surface temperatures have risen, is one possible explanation for the decline in sunshine. A strong negative correlation was confirmed between sunshine factors from ground-based observations and satellite-based cloud factors over Ireland. In addition, it was found that cloud factors over Ireland correlated well with cloud factors over large oceanic areas such as the North Atlantic and mid-high latitudes generally. Thus cloud factors (and similarly sunshine factors) from regions on the boundaries of large oceans which lie in the direction of the prevailing wind could be useful in determining the long-term changes in cloud factors over more extended areas. Knowledge of such long term variability in the Earth's cloud cover is important input information for modelling past climate change. The importance of cosmic rays as a link between solar activity and climate was assessed from a study of the ISCCP-D2 satellite cloud factors and Irish sunshine data. Whilst these results confirmed the strong correlation between total cloud factor and cosmic rays over non-tropical oceans between 1984 and 1991 previously reported, it was found that this correlation did not hold in the subsequent period 1991-1994. Other work has established a link through specifically low cloud. Indirect evidence of cloud formation by cosmic rays from a variation in the sunshine factor following Forbush decreases, and over the sunspot cycle, was mostly negative. Although a dip at seven years past sunspot minimum is evident in the sunshine factor for all four sites and in most seasons, it is of marginal statistical significance. Copyright © 2001 Royal Meteorological Society."
"7007026915;6602292934;22946263800;7401509344;7005050002;","Summer season land cover - Convective cloud associations for the Midwest U.S. ""corn belt""",2001,"10.1029/2000GL012635","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035334744&doi=10.1029%2f2000GL012635&partnerID=40&md5=a249a28663876145d94d25bbdc914fcf","Human-induced land cover modifications impact the planetary boundary layer's (PBL) thermal and moisture regimes on mesoscales. We investigate the association of croplands, forest, and the crop-forest ""boundary"" (CFB) with convective-cloud development (timing, amount) for three target areas (TAs) in the U.S. Midwest Corn Belt, during the summer seasons (JJA) 1991-98. For each land cover, hourly satellite-retrieved albedo and cloud-top temperature values are composited for three classes of mid-tropospheric synoptic circulation. On days with the strongest anticyclonicity, there are no consistent differences in convection related to land cover type: Cloud development is regionalized and tied primarily to synoptic conditions. However, on days having weaker anticyclonicity the CFB is the dominant site of free convection, suggesting that Non-Classical Mesoscale Circulations (NCMCs) between cropped and adjacent forest areas may operate when reduced subsidence in the mid-troposphere does not effectively cap the PBL. Index terms: Land/atmosphere interactions (3322), Mesoscale meteorology (3329), Climate dynamics (1620), Anthropogenic effects (1803)."
"7005070958;55745955800;7004325649;7404150761;7410092917;7003947691;","The influence of the 1998 El Niño upon cloud-radiative forcing over the Pacific warm pool",2001,"10.1175/1520-0442(2001)014<2129:TIOTEN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035325008&doi=10.1175%2f1520-0442%282001%29014%3c2129%3aTIOTEN%3e2.0.CO%3b2&partnerID=40&md5=337e7a82a5121062c391e12e89a90c10","Clouds cool the climate system by reflecting shortwave radiation and warm it by increasing the atmospheric greenhouse. Previous studies have shown that in tropical regions of deep convection there is a near cancellation between cloud-induced shortwave cooling and longwave warming. The present study investigates the possible influence of the 1998 El Niño upon this near cancellation for the tropical western Pacific's warm pool; this was accomplished by employing satellite radiometric measurements (Earth Radiation Budget Experiment, and Clouds and the Earth's Radiant Energy System). With the exclusion of the 1998 El Niño, this study also finds near cancellation between the shortwave and longwave cloud forcings and demonstrates that it refers to the average of different cloud types rather than being indicative of a single cloud type. The shortwave cooling slightly dominates the longwave warming, and there is considerable interannual variability in this modest dominance that appears attributable to interannual variability of tropopause temperature. For the strong 1998 El Niño, however, there is a substantially greater tendency toward net radiative cooling, and the physical mechanism for this appears to be a change in cloud vertical structure. For normal years, as well as for the weaker 1987 El Niño, high clouds dominate the radiation budget over the warm pool. In 1998, however, the measurements indicate the radiation budget is partially governed by middle-level clouds, thus explaining the net cooling over the warm pool during the 1998 El Niño as well as emphasizing differences between this event and the weaker 1987 El Niño."
"26027537400;23479679000;","An analysis of climatic parameters and sky condition classification",2001,"10.1016/S0360-1323(00)00027-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035324658&doi=10.1016%2fS0360-1323%2800%2900027-5&partnerID=40&md5=99e7b56ad1b759b845497bd1b92d03da","In modelling solar radiation, of the required data daylight illuminance, luminous efficacy, radiance and luminance sky distributions, are always analysed under various sky types. Sky conditions are frequently categorised into overcast, partly cloudy and clear using some common climatic data including cloud cover (CLD), sunshine hour (SH) and solar radiation. This paper presents the study of these climatic parameters and their applications in the classification of sky condition. Frequency of occurrence and cumulative frequency distribution of each sky indicator have been established to interpret the prevailing sky conditions in Hong Kong. Special features on defining the sky clearness are highlighted and the implications for energy-efficient building designs are discussed. © 2000 Elsevier Science Ltd. All rights reserved."
"55715079700;7006095466;","Long-term behavior of cloud systems in TOGA COARE and their interactions with radiative and surface processes. Part III: Effects on the energy budget and SST",2001,"10.1175/1520-0469(2001)058<1155:LTBOCS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035334377&doi=10.1175%2f1520-0469%282001%29058%3c1155%3aLTBOCS%3e2.0.CO%3b2&partnerID=40&md5=1f50a3a0ea4264373d2ef00aaf1386c1","Most atmospheric general circulation models (GCMs) and coupled atmosphere-ocean GCMs are unable to get the tropical energy budgets at the top of the atmosphere and the surface to simultaneously agree with observations. This aspect is investigated using a cloud-resolving model (CRM) that treats cloud-scale dynamics explicitly, a single-column model (SCM) of the National Center for Atmospheric Research (NCAR) Community Climate Model that parameterizes convection and clouds, and observations made during Tropical Oceans and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). The same large-scale forcing and radiation parameterizations were used in both modeling approaches. We showed that the time-averaged top-of-atmosphere and surface energy budgets agree simultaneously with observations in a 30-day (5 December 1992-3 January 1993) cloud-resolving simulation of tropical cloud systems. The 30-day time-averaged energy budgets obtained from the CRM are within the observational accuracy of 10 W m-2, while the corresponding quantities derived from the SCM have large biases. The physical explanation for this difference is that the CRM realization explicitly represents cumulus convection, including its mesoscale organization, and produces vertical and horizontal distributions of cloud condensate (ice and liquid water) that interact much more realistically with radiation than do parameterized clouds in the SCM. The accuracy of the CRM-derived surface fluxes is also tested by using the fluxes to force a one-dimensional (ID) ocean model. The ID model, together with the surface forcing from the CRM and the prescribed advection of temperature and salinity, simulates the long-term evolution and diurnal variation of the sea surface temperature. This suggests that the atmosphere-ocean coupling requires accurate representation of cloud-scale and mesoscale processes."
"35453054300;","Influence of the spatial distribution of vegetation and soils on the prediction of cumulus convective rainfall",2001,"10.1029/1999RG000072","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034936141&doi=10.1029%2f1999RG000072&partnerID=40&md5=8dec237d5d0f284d968900799a5f0d00","This paper uses published work to demonstrate the link between surface moisture and heat fluxes and cumulus convective rainfall. The Earth's surface role with respect to the surface energy and moisture budgets is examined. Changes in land-surface properties are shown to influence the heat and moisture fluxes within the planetary boundary layer, convective available potential energy, and other measures of the deep cumulus cloud activity. The spatial structure of the surface heating, as influenced by landscape patterning, produces focused regions for deep cumulonimbus convection. In the tropics, and during midlatitude summers, deep cumulus convection has apparently been significantly altered as a result of landscape changes. These alterations in cumulus convection teleconnect to higher latitudes, which significantly alters the weather in those regions. The effect of tropical deforestation is most clearly defined in the winter hemisphere. In the context of climate, landscape processes are shown to be as much a part of the climate system as are atmospheric processes."
"7006198994;7202145115;","The sensitivity of intraseasonal variability in the NCAR CCM3 to changes in convective parameterization",2001,"10.1175/1520-0442(2001)014<2015:TSOIVI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035324964&doi=10.1175%2f1520-0442%282001%29014%3c2015%3aTSOIVI%3e2.0.CO%3b2&partnerID=40&md5=54e668e3bd896a48ac91a04df059acd9","The National Center for Atmospheric Research (NCAR) Community Climate Model, version 3.6 (CCM3) simulation of tropical intraseasonal variability in zonal winds and precipitation can be improved by implementing the microphysics of cloud with relaxed Arakawa-Schubert (McRAS) convection scheme of Sud and Walker. The default CCM3 convection scheme of Zhang and McFarlane produces intraseasonal variability in both zonal winds and precipitation that is much lower than is observed. The convection scheme of Hack produces high tropical intraseasonal zonal wind variability but no coherent convective variability at intraseasonal timescales and low wavenumbers. The McRAS convection scheme produces realistic variability in tropical intraseasonal zonal winds and improved intraseasonal variability in tropical precipitation, although the variability in precipitation is somewhat less than is observed. Intraseasonal variability in CCM3 with the McRAS scheme is highly sensitive to the parameterization of convective precipitation evaporation in unsaturated environmental air and unsaturated downdrafts. Removing these effects greatly reduces intraseasonal variability in the model. Convective evaporation processes in McRAS affect intraseasonal variability mainly through their time-mean effects and not through their variations. Convective rain evaporation and unsaturated downdrafts improve the modeled specific humidity and temperature climates of the Tropics and increase convection on the equator. Intraseasonal variability in CCM3 with McRAS is not improved by increasing the boundary layer relative humidity threshold for initiation of convection, contrary to the results of Wang and Schlesinger. In fact, intraseasonal variability is reduced for higher thresholds. The largest intraseasonal moisture variations during a model Madden-Julian oscillation life cycle occur above the boundary layer, and humidity variations within the boundary layer are small."
"7201844203;7403497924;7402521017;","A sea surface radiation data set for climate applications in the tropical western Pacific and South China Sea",2001,"10.1029/2000JD900661","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034957372&doi=10.1029%2f2000JD900661&partnerID=40&md5=9fceee7c7416577b79d7589f62a86215","The sea surface shortwave and longwave radiative fluxes have been retrieved from the radiances measured by Japan's Geostationary Meteorological Satellite 5. The surface radiation data set covers the domain 40° S-40° N and 90° E-170° W and a period starting from January 1998. The temporal resolution is 1 day, and the spatial resolution is 0.5°×0.5° latitude-longitude. The retrieved surface radiation has been validated with the radiometric measurements at the Atmospheric Radiation Measurement (ARM) site on Manus Island in the equatorial western Pacific. It has also been validated with the measurements at the radiation site on Dungsha Island during the South China Sea Monsoon Experiment (SCSMEX) (May and June 1998). The data set is used to study the effect of El Nino and East Asian summer monsoon on the heating of the ocean. Interannual variations of clouds associated with El Nino and the East Asian summer monsoon have a large impact on the radiative heating of the ocean, exceeding 40 W m-2 in seasonal mean over large areas. Together with the Clouds and the Earth's Radiant Energy System (CERES) shortwave fluxes at the top of the atmosphere and the radiative transfer calculations of clear-sky fluxes, this surface radiation data set is also used to study the impact of clouds on the solar heating of the atmosphere. It is found that clouds enhance the atmospheric solar heating by ∼21 W m-2 in the tropical western Pacific and the South China Sea. Copyright 2001 by the American Geophysical Union."
"7006705919;56520921400;7102645933;","Understanding the Indian Ocean Experiment (INDOEX) aerosol distributions with an aerosol assimilation",2001,"10.1029/2000JD900508","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034960461&doi=10.1029%2f2000JD900508&partnerID=40&md5=0042f4c2f1566db25a600f47ca65bece","We use the aerosol assimilation procedure described by Collins et al. [2000] to help explain INDOEX aerosol distributions. The procedure combines modeled aerosol with AVHRR satellite estimates. The result is consistent with satellite measurements, regular in space and time, and provides information where retrievals are difficult (over land, coincident with clouds, and at night). Extra information on aerosol composition, vertical distribution, and region of origin is also produced. Carbonaceous, sulfate, and sea salt aerosols agree with the in situ measurements to 10-20%. Carbonaceous aerosols were estimated to be the dominant contributor (36%) to the aerosol optical depth (AOD); dust (31%) and sulfate (26%) were also important. The residence time for sulfate and carbon is ∼7 and ∼8 days respectively, longer than globally averaged residence times of many modeling studies. Thus aerosols produced here during the winter monsoon may have a larger climate impact than the same emissions occurring where the residence time is shorter. Three points of entry are found for anthropogenic aerosol to the INDOEX region: a strong near surface southward flow near Bombay; a deeper plume flowing south and east off Calcutta and a westward flow originating from southeast Asia and entering the Bay of Bengal. All three plumes are strongly modulated by a low-frequency change of meteorological regime associated with the Madden Julian Oscillation. The analysis suggests that India is the dominant source of aerosol in the Arabian Sea and Bay of Bengal near the surface but that Asia, Africa and the rest of world also contribute at higher altitudes. India and Asia contribute ∼40% each to the total column mass of air reaching the Maldives, the balance of air comes from other source regions. The assimilation procedure produces an analysis that is a synergy in information about aerosols, that is not easily accessible by independent estimates from remote sensing, in situ measurements, or global transport models by themselves. Copyright 2001 by the American Geophysical Union."
"6701333444;13406672500;7003561442;","Scale dependence of solar heating rates in convective cloud systems with implications to general circulation models",2001,"10.1175/1520-0442(2001)014<1738:SDOSHR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035870115&doi=10.1175%2f1520-0442%282001%29014%3c1738%3aSDOSHR%3e2.0.CO%3b2&partnerID=40&md5=89a1833a597378eb5889a1349c3f7b41","The authors examine 3D solar radiative heating rates within tropical convective-cirrus systems to identify the scales that contribute significantly to the spatial average over a climate model's grid cell (i.e., its grid mean), and determine their relationship to the cloud field properties (e.g., cloud-top height variation). These results are used to understand the spatial resolution and subgrid-scale cloud property information needed in climate models to accurately simulate the grid-mean solar heating of these systems. The 3D heating rates are computed by a broadband Monte Carlo model for several regional-scale cloud fields [(400 km)2] whose properties are retrieved from satellite data over the tropical western Pacific. The analyses discussed in this paper have identified two key subrid-scale features within these systems that largely govern the grid-mean heating rates: the variability in the cloud-top height, and the structure of the cloud edge. These features give rise to hot spots-regions of intense local heating that occupy a small area but dominate the gridmean value. For example for the fields considered here, 5%-25% of the grid area can contribute 30%-60% of the total heating rate, respectively. Explicitly resolving the hot spots requires a model grid of about (20 km)2-(30 km)2 which is smaller than that currently used in general circulation models (GCMs) for weather forecasting and about a factor of 20 smaller than that used for climate studies. It is shown that, unless a grid of ∼(20 km)2 is used, GCM-style heating rate calculations that employ a standard cloud overlap-type treatment can significantly overestimate the solar heating aloft and underestimate it below. This might enhance the vertical velocity within the cloud layer and suppress it at cloud base. Thus, over the long term, biases in the GCM treatments of the vertical heating rate might have consequences to cloud evolution and feedback, particularly for clouds in weak local dynamical regimes."
"7201785152;7404211378;7005132811;7102403008;7003979342;","Dynamical and cloud-radiation feedbacks in El Niño and greenhouse warming",2001,"10.1029/2000GL012078","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035870441&doi=10.1029%2f2000GL012078&partnerID=40&md5=5583fa888088d13386ceb1181ee0a679","An E1 Niño-like steady response is found in a greenhouse warming simulation resulting from coupled ocean-atmosphere dynamical feedbacks similar to those producing the present-day E1 Niños. There is a strong negative cloud-radiation feedback on the sea surface temperature (SST) anomaly associated with this enhanced eastern equatorial Pacific warm pattern. However, this negative feedback is overwhelmed by the positive dynamical feedbacks and cannot diminish the sensitivity of the tropical SST to enhanced greenhouse gas concentrations. The enhanced eastern-Pacific warming in the coupled ocean-atmosphere system suggests that coupled dynamics can strengthen this sensitivity."
"6701656335;7202803069;","On the relationship of cosmic ray flux and precipitation",2001,"10.1029/2000GL012536","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035870404&doi=10.1029%2f2000GL012536&partnerID=40&md5=82e3e2a5a6d9189fd98864af28e72e05","This paper evaluates whether there is empirical evidence to support the hypothesis that solar variability is linked to the Earth's climate through the modulation of atmospheric precipitation processes. Using global data from 1979-1999, we find evidence of a statistically strong relationship between cosmic ray flux (CRF), precipitation (P) and precipitation efficiency (PE) over ocean surfaces at mid to high latitudes. Both P and PE are shown to vary by 7-9% during the solar cycle of the 1980s over the latitude band 45-90°S. Alternative explanations of the variation in these atmospheric parameters by changes in tropospheric aerosol content and ENSO show poorer statistical relationships with P and PE. Variations in P and PE potentially caused by changes in CRF have implications for the understanding of cloud and water vapour feedbacks."
"35339707100;57202301596;6701797281;7102870914;","Tropical Atlantic air-sea interaction and its influence on the NAO",2001,"10.1029/2000GL012565","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035870403&doi=10.1029%2f2000GL012565&partnerID=40&md5=a5ff91f02af6bd0f96aa4b1f3d509ee8","An atmospheric general circulation model (AGCM) is forced with a prescribed SST dipole anomaly in the tropical Atlantic to investigate the cause of cross-equatorial SST gradient (CESG) variability and its teleconnection to the extratropics. The model response bears a striking resemblance to observations in both the tropics and extratropics. The tropical response is robust and can act to reinforce the prescribed SST anomalies through wind-induced evaporation. A new feedback mechanism involving low-level stratiform clouds in the subtropics is also identified in the model and observations. The tropical SST dipole forces a barotropic teleconnection into the extratropics that projects onto the North Atlantic Oscillation (NAO). It further induces the extratropical portion of the North Atlantic SST tripole when the AGCM is coupled with an ocean mixed layer model. CESG variability thus appears to be the centerpiece of a pan-Atlantic climate pattern observed to extend from the South Atlantic to Greenland."
"7003777747;7003434501;7003614389;","Historical evolution of radiative forcing of climate",2001,"10.1016/S1352-2310(00)00531-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034744204&doi=10.1016%2fS1352-2310%2800%2900531-8&partnerID=40&md5=af7ef62be7bedb6d00b5e310f03f6b19","We have compiled the evolution of the radiative forcing for several mechanisms based on our radiative transfer models using a variety of information sources to establish time histories. The anthropogenic forcing mechanisms considered are well-mixed greenhouse gases, ozone, and tropospheric aerosols (direct and indirect effect). The natural forcing mechanisms taken into account are the radiative effects of solar irradiance variation and particles of volcanic origin. In general there has been an increase in the radiative forcing during the 20th century. The exception is a decline in the radiative forcing in the 1945-1970 period. We have found that the evolution of anthropogenic particle emissions in the same period may have been a major cause of this decline in the forcing. We have discussed uncertainties in the various forcings and their evolution. The uncertainties are large for many forcing mechanisms, especially the impact of anthropogenic aerosols. In particular the indirect effect of aerosols on clouds is difficult to quantify. Several evolutions of their effect may have been possible, strongly influencing the evolution of the total anthropogenic radiative forcing. Copyright © 2001 Elsevier Science Ltd."
"7102505167;7005284248;","Seasonal and interannual variability in atmospheric turbidity over South Africa",2001,"10.1002/joc.629","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035310599&doi=10.1002%2fjoc.629&partnerID=40&md5=64e93e799a56a0ae1c7e36204b3b4029","Aerosols affect climate by attenuating solar radiation and acting as cloud condensation nuclei. Despite their importance in the climate system, our understanding of the time-space variability of aerosols is fragmentary. Measurements and reliable estimates of atmospheric turbidity-the total column amount of aerosol-are scarce in most countries and this is especially true in the Southern Hemisphere. Very little is known about the seasonal, interannual and spatial variability of aerosols over the southern half of the globe. In this paper, we estimate monthly averaged atmospheric turbidity from surface climate data at eight locations in South Africa, regardless of cloud cover. Findings include new estimates of turbidity trends and variability over South Africa. Seasonal trends are evident at many stations, although there is no consistent trend. Over recent decades, turbidity has generally been stable at six of the eight stations. Our methodology can be applied at any location where the requisite climate data are available and, therefore, holds promise for a more complete, and possibly global, climatology of aerosols. Copyright © 2001 Royal Meteorological Society."
"7005706662;13406672500;","Scale dependence of the thermodynamic forcing of tropical monsoon clouds: Results from TRMM observations",2001,"10.1175/1520-0442(2001)014<1511:SDOTTF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035298018&doi=10.1175%2f1520-0442%282001%29014%3c1511%3aSDOTTF%3e2.0.CO%3b2&partnerID=40&md5=eda7f84510025b95444c80ee6c773b89","Clouds exert a thermodynamic forcing on the ocean-atmosphere column through latent heating, owing to the production of rain, and through cloud radiative forcing, owing to the absorption of terrestrial infrared energy and the reflection of solar energy. The Tropical Rainfall Measuring Mission (TRMM) satellite provides, for the first time, simultaneous measurements of each of these processes on the spatial scales of individual clouds. Data from TRMM are used to examine the scale dependence of the cloud thermodynamic forcing and to understand the dominant spatial scales of forcing in monsoonal cloud systems. The tropical Indian Ocean is chosen, because the major monsoonal cloud systems are located over this region. Using threshold criteria, the satellite data are segmented into rain cells (consisting of only precipitating pixels) and clouds (consisting of precipitating as well as nonprecipitating pixels), ranging in scales from 103 km2 to 106 km2. For each rain cell and cloud, latent heating is estimated from the microwave imager and radiative forcing is estimated from the Cloud and the Earth's Radiant Energy System radiation budget instrument. The sizes of clouds and rain cells over the tropical Indian Ocean are distributed lognormally. Thermodynamic forcing of clouds increases with rain cell and cloud area. For example, latent heating increases from about 100 W m-2 for a rain cell of 103 km2 to as high as 1500 W m-2 for a rain cell of 106 km2. Correspondingly, the liquid water path increases tenfold from 0.3 to nearly 3 kg m-2, the longwave cloud forcing from 30 to 100 W m-2, and the diurnal mean shortwave cloud forcing from -50 to -150 W m-2. Previous studies have shown that in regions of deep convection, large clouds and rain cells express greater organization into structures composed of convective core regions attached to stratiform anvil cloud and precipitation. Entrainment of moist, cloudy air from the stratiform anvil into the convective core helps to sustain convection against the entrainment of unsaturated air. Thus large clouds produce more rain, trap more terrestrial radiation, and reflect more solar energy than do smaller clouds. The combined effect of increased forcing and increased spatial coverage means that larger clouds contribute most of the total forcing. Rain cells larger than 105 km2 make up less than 2% of the rain cell population, yet contribute greater than 70% of the latent heating. Similarly, the clouds larger than 105 km2, in which the largest rain cells are embedded, make up less than 3% of clouds, yet are the source of greater than 90% of the total thermodynamic forcing. Significant differences are apparent between the scales of latent heating and radiative forcing, as only about 25% of cloud area is observed to precipitate. The fraction of clouds that contain some rain increases dramatically from about 5% for the smaller scale (103 km2) to as high as 90% for the largest scale considered here (106 km2). The fractional area of the precipitating cloud ranges from 0.2 to 0.4 with a hybrid-scale dependence. Greater than one-half of radiative forcing is provided by nonprecipitating anvil portions of deep convective cloud systems. The results presented here have significant implications for the parameterization of clouds and rain in GCMs and washout of solute trace gases and aerosols in chemistry and transport models."
"7004600107;","Evaluation of the mass-flux approach to parametrizing deep convection",2001,"10.1256/smsqj.57405","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035301798&doi=10.1256%2fsmsqj.57405&partnerID=40&md5=bf04bf2e9a8fa7ba71c0301750011d25","Cloud-resolving model (CRM) simulations of deep convection in a variety of environmental conditions are used to analyse assumptions in bulk-updraught convection parametrization schemes, which are commonly employed in climate and weather-prediction models. It is shown that the mass-flux approach can faithfully represent the effect of convection on the large-scale fields, provided that the mass flux and other bulk properties of the updraughts (and downdraughts) are accurately predicted. Entrainment and detrainment (which govern the shape of the mass-flux profile and the dilution of the bulk updraught with environment air) are calculated from CRM simulations. Limitations in the basic premiss of the classical entraining/detraining plume model are revealed and an alternative method of predicting bulk-updraught temperature is suggested."
"7003566416;6602332621;7005228425;7102188656;","Fine mode particulate sulphur in the tropopause region measured from intercontinental flights (CARIBIC)",2001,"10.1029/2000GL012257","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035302689&doi=10.1029%2f2000GL012257&partnerID=40&md5=644344d59e33ae4d954182d08729ea5c","Here the first systematic study of the concentration of particulate sulphur in the upper troposphere and lower stratosphere is presented. The measurements were undertaken in the CARIBIC programme during intercontinental flights from a commercial aircraft, which was equipped with an aerosol inlet and a research payload in the cargo bay. Aerosol samples were collected and analysed for elemental composition. The data set comprises 21 flights between Germany and Male/Colombo in the Indian Ocean. The average fine mode, particulate sulphur concentration was 14 ng/m3 STP, which is low compared to remote areas at the Earth's surface. A pronounced dependence with latitude with elevated concentrations occurring within the densely industrialised northern hemispheric mid latitudes was observed, thus suggesting anthropogenic influence on the climate from sulphate particles in the tropopause region."
"7004894250;7201771183;","The Role of Ground-Based GPS Meteorological Observations in Numerical Weather Prediction",2001,"10.1007/PL00012860","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001893966&doi=10.1007%2fPL00012860&partnerID=40&md5=daf6f8f1e51d7b03e8bdf8799006989a","For lack of sufficient observations, the definition of atmospheric moisture fields (including water vapor and clouds) remains a difficult problem whose solution is essential for improved weather forecasts. Moisture fields are under-observed in time and space, primarily because the distribution of water in the atmosphere is highly variable. Because water is important in weather and climate processes, a significant effort has been expended to develop new or improved remote sensing systems to mitigate this problem. One such system uses ground-based Global Positoning System (GPS) receivers to make accurate all-weather estimates of atmospheric refractivity at very low cost. This largely unanticipated application of GPS had led to a new and potentially significant upper-air observing system for meteorological agencies and researchers around the world (Wolfe & Gutman, 2000). The first and most mature use of GPS for this purpose is in the estimation of integrated (total column) precipitable water vapor above a fixed site (Duan et al., 1996, with improvements by Niell, 1996, and Fang et al., 1998). The techniques currently used by the National Oceanic and Atmospheric Administration's Forecast Systems Laboratory (NOAA/FSL) to collect, process, and distribute GPS water vapor observations are mature and almost ready for transition to operational use. NOAA/FSL has shown that GPS integrated water vapor data can be used effectively in objective (i. e., numerical weather prediction) and subjective weather forecasting. To understand the strengths and limitations of GPS for weather forecasting, it is essential to understant what types of information are currently available to forecasters and modelers, and how models use the data to describe the current and probable future state of the atmosphere. It is also important to understand the current trends in modern weather prediction to ensure that GPS observing system play a significant role in the future. © 2001 John Wiley & Sons, Inc. © 2001, John Wiley & Sons, Inc."
"56000281400;57206159232;6603989070;","Variability of Cloud Microphysical and Optical Parameters Obtained from Aircraft and Satellite remote sensing measurements during race",2001,"10.1002/joc.582","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035970421&doi=10.1002%2fjoc.582&partnerID=40&md5=ceeb249cc9a4e0792e8f1cc3769487dc","Observations of low stratiform clouds made during the Radiation, Aerosol and Cloud Experiment (RACE) over the Bay of Fundy, Nova Scotia, on 15 August 1995, and central Ontario on 4 October 1995 were used in this study. Aircraft, LAND Resources SATellite System (LANDSAT) and the Center for Atmospheric Research Experiments (CARE) lidar observations are used to obtain effective radius (reff), droplet number concentration (Nd) and cloud optical thickness (τ). Radiation observations with 28.5 m resolution from the Thematic Mapper (TM) on LANDSAT were used. The 10.4-12.5 μm infrared channel with a field of view of 114 m was used for the blackbody temperature calculation. Comparisons are made between clouds over the Ontario region, representing clouds over the land and over the Bay of Fundy, representing clouds over the ocean. Results of the aircraft observations show that the leg averaged Nd, liquid water content (LWC) and reff over land were about 147 ± 73 cm-3, 0.21 ± 0.11 g m-3 and 7.7± 1.7 μm, respectively. Corresponding parameters for the clouds over the ocean were approximately 61 ± 34 cm-3, 0.12 ± 0.07 g m-3 and 13.8 ± 3 μm, respectively. The mean measured visible extinction coefficient (σext) was about 55 ± 15 km-1 for all cases, and it was a strong function of both LWC and Nd. The horizontal variability in both aircraft and LANDSAT observations indicate the need to address inhomogeneity in the sub-grid scales of models. Copyright © 2001 Royal Meteorological Society."
"7003666669;7006270084;7101909551;6602973136;36538539800;7202048112;7004575544;7003777379;6603268269;","A physically based estimate of radiative forcing by anthropogenic sulfate aerosol",2001,"10.1029/2000JD900503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034962111&doi=10.1029%2f2000JD900503&partnerID=40&md5=e072e34fd87671ef85db571c0b387cd0","Estimates of direct and indirect radiative forcing by anthropogenic sulfate aerosols from an integrated global aerosol and climate modeling system are presented. A detailed global tropospheric chemistry and aerosol model that predicts concentrations of oxidants as well as aerosols and aerosol precursors, is coupled to a general circulation model that predicts both cloud water mass and cloud droplet number. Both number and mass of several externally mixed aerosol size modes are predicted, with internal mixing assumed for the different aerosol components within each mode. Predicted aerosol species include sulfate, organic and black carbon, soil dust, and sea salt. The models use physically based treatments of aerosol radiative properties (including dependence on relative humidity) and aerosol activation as cloud condensation nuclei. Parallel simulations with and without anthropogenic sulfate aerosol are performed for a global domain. The global and annual mean direct and indirect radiative forcing due to anthropogenic sulfate are estimated to be -0.3 to -0.5 and -1.5 to -3.0 W m-2, respectively. The radiative forcing is sensitive to the model's horizontal resolution, the use of predicted versus analyzed relative humidity, the prediction versus diagnosis of aerosol number and droplet number, and the parameterization of droplet collision/ coalescence. About half of the indirect radiative forcing is due to changes in droplet radius and half to increased cloud liquid water. Copyright 2001 by the American Geophysical Union."
"7007133317;6701417648;6506428225;","Anomalously high values of cesium-137 in soils on the Península de Paraguana (Venezuela)",2001,"10.1023/A:1010642812993","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035103559&doi=10.1023%2fA%3a1010642812993&partnerID=40&md5=e85881dd2f5312d9d4dfd2f1a10a6cfc","The activity of 137Cs in surface soils (2-5 cm) was determined at twenty-one sampling sites along the northwestern and eastern coast of the Paraguana peninsula (Venezuela), as well as, at nine locations, between 95 and 535 m.a.s.l. on Cerro Santa Ana. The measurements were performed by high-resolution gamma-ray spectroscopy employing a compatible IBM computer. Most of the values were much higher than those found along the coastline of the mainland; four sites were found to be anomalously high with 137Cs values greater than 10 Bq/kg. It is difficult to explain these anomalous 137Cs values by geographical or climatological factors since there is little rainfall here and the clouds and fog are rarely if never present along the coast of the peninsula. Possibly, some mechanism of the mist that is blown ashore could explain these anomalies. The values of the 137Cs versus altitude on the Cerro Santa Ana show an increase of two or three times at 500 m.a.s.l. level, thus we have concluded that the base of the clouds was at this height when the fallout was directly deposited by condensation in this cloud forest. These results in the Cerro Santa Ana cloud forest are similar to those of other cloud forests along the Venezuelan coast, but the altitude (m.a.s.l.) of the base of the clouds here are much lower."
"7005196173;56033135100;","Validation of ECMWF (RE)analysis surface climate data, 1979-1998, for greenland and implications for mass balance modeling of the ice sheet",2001,"10.1002/joc.609","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035097840&doi=10.1002%2fjoc.609&partnerID=40&md5=dec21403377a809490c24e891efcd1a1","Climate (re)analysis products are potentially valuable tools, when properly verified, for helping to constrain the surface mass balance of the Greenland Ice Sheet (GIS). Monthly surface fields from European Centre for Medium-Range Weather Forecasts (ECMWF) operational- and re-analyses spanning 1979-1998 were validated using in situ data (surface air pressure and temperature, precipitation, cloud cover, short-/all-wave radiation, and wind speed/direction). These validation data are from coastal or near-coastal Danish Meteorological Institute (DMI) synoptic stations, inland Greenland Climate Network (GC-Net) and University of Wisconsin Automatic Weather Stations (AWSs), and two energy balance stations near the southern ice margin. The ECMWF analyses closely reproduce the seasonal patterns and interannual variations of much of the in situ data. Differences in the mean values of surface air pressure and temperature can mainly be ascribed to orography errors in the analyses' schemes, compared with the latest available accurate digital elevation model. Much of the GIS margin as modelled by ECMWF was too cold, on average by 4°C, and ECMWF precipitation averaged some 136% of the DMI station values. The misrepresentation of the (relatively) steep ice-sheet margin, which tends to be broadened and systematically over-elevated by several hundred metres, orographically reduced temperature and enhanced precipitation there in the ECMWF models. The cloud-cover comparison revealed not dissimilar annual mean cloud covers (ECMWF - 8%) but the ECMWF analyses had too little cloud and were too 'sunny' during the critical summer melt-season. ECMWF-modelled surface albedo in summer was Ο 11% lower than GC-Net values, which was mainly responsible for the disagreement of modelled surface short-wave radiation fluxes with observations. Model albedo and cloud errors need to be rectified if the analyses are to be used effectively to drive energy balance models of Greenland snowmelt. ECMWF wind speed averaged 66% (62%) of the DMI station (AWS) values. The validation results provide useful insights into how one can best improve the ECMWF Greenland climate data for use in glaciological and climatological studies. Copyright © 2001 Royal Meteorological Society."
"7006308157;","Disaggregating climatic trends by classification of circulation patterns",2001,"10.1002/joc.605","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035090799&doi=10.1002%2fjoc.605&partnerID=40&md5=65c8941e3beb5f46d1ec6d42f3d3b790","The trends in occurence frequencies of circulation types over Europe and in nine climate variables in the Czech Republic conditioned by the types are examined for period 1949-1980. The circulation types are determined by an objective procedure from daily 500 hPa heights. Both in summer and winter, anticyclonic types have become more frequent at the expense of cyclonic types. The circulation changes are shown to be unrelated to the trends in surface climate elements in summer, whereas in winter, trends in circulation explain a part of the observed warming and strengthening of southerly winds. The trends in climate elements are not uniform among circulation types. In summer, the trend pattern consisting of decreasing maximum and daily mean temperatures, daily temperature range (DTR) and sunshine duration, and increasing cloudiness and relative humidity is observed under the cyclonic types and the types with a well-pronounced jet, but is missing under types with a blocking anticyclone over Europe. Two possible mechanisms causing this trend pattern are proposed: increasing cloudiness, and a process responsible for the reduction of sunshine without a concurrent increase of cloudiness. The latter mechanism can possibly be identified with increasing aerosol concentrations. In winter, the degree of warming is governed by changes in zonal wind. The mechanism of change in DTR seems to vary with elevation: at the lowland station (Prague-Klementinum), the increase in DTR is related to the warming trend, and consequently with zonal wind changes, while at the mountain station (Milesovka), the increase in DTR reflects the increase in precipitating clouds. The changes in DTR are related much more to mid-tropospheric circulation than to cloud cover in summer, whereas in winter, cloud cover plays a more important role in affecting DTR trends. Copyright © 2001 Royal Meteorological Society."
"56520921400;","Effects of enhanced shortwave absorption on coupled simulations of the tropical climate system",2001,"10.1175/1520-0442(2001)014<1147:EOESAO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035869794&doi=10.1175%2f1520-0442%282001%29014%3c1147%3aEOESAO%3e2.0.CO%3b2&partnerID=40&md5=042e605e8efae496b324edc6b16454d1","The effects of enhanced shortwave absorption on coupled simulations of the tropical climate have been tested using the National Center for Atmospheric Research Climate System Model. The enhancement in cloudy-sky shortwave absorption is consistent with several recent intercomparisons of models and observations. The primary reasons for introducing enhanced absorption are to improve the fidelity of the modeled shortwave fluxes in comparison with observations, to improve the simulation of sea surface temperature in the tropical Pacific, and to reduce or eliminate transient behavior in the model associated with compensating errors between latent heat fluxes and surface insolation. The simulations incorporate a new method to increase shortwave absorption in cloudy atmospheres. In previous studies, adjustments to cloud optical properties or modifications to the shortwave radiative transfer were used to increase shortwave cloud absorption. In the new ""generic"" implementation, the in-cloud shortwave flux divergences have been adjusted to yield the observed global surface insolation while leaving the top-of-atmosphere fluxes fixed. The simulations with enhanced absorption show that several aspects of the atmospheric state and ocean-atmosphere fluxes are much closer to observational estimates. All the terms in the surface and top-of-atmosphere heat budget of the western Pacific warm pool are within 4 W m-2 of the measured values. The latent heal fluxes are within 10-15 W m-2 of estimates from buoy data over most of the tropical Pacific. Without absorption, the model consistently overestimates the latent heat fluxes. The differences between the observed and simulated sea surface temperatures in the equatorial Pacific are reduced from 2 K to less than 1 K with the introduction of enhanced absorption."
"35461763400;7004864963;57213653167;10144282600;7101603186;7007155334;8058018000;56087454800;35593636200;8387048600;7005219614;8309525000;6603785227;7402833686;6602208927;6602402116;57201177267;7102862273;56490302800;49965038800;","Transport of biomass burning smoke to the upper troposphere by deep convection in the equatorial region",2001,"10.1029/2000GL012391","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17844382732&doi=10.1029%2f2000GL012391&partnerID=40&md5=896bb7ba5ba806e11e3a6a9204af2439","During LBA-CLAIRE-98, we found atmospheric layers with aged biomass smoke at altitudes &gt; 10 km over Suriname. CO, CO2, acetonitrile, methyl chloride, hydrocarbons, NO, O3, and aerosols were strongly enhanced in these layers. We estimte that 80-95% of accumulation mode aerosols had been removed during convective transport. Trajectories show that the plumes originated from large fires near the Brazil/Venezuela border during March 1998. This smoke was entrained into deep convection over the northern Amazon, transported out over the Pacific, and then returned to South America by the circulation around a large-upper-level anticyclone. Our observations provide evidence for the importance of deep convection in the equatorial region as a mechanism to transport large amounts of pyrogenic pollutants into the upper troposphere. The entrainment of biomass smoke into tropical convective clouds may have significant effects on cloud microphysics and climate dynamics."
"6506587415;6701633912;7005516084;6701744275;","Regional diurnal albedo climatology and diurnal time extrapolation of reflected solar flux observations: Application to the ScaRaB record",2001,"10.1175/1520-0442(2001)014<1129:RDACAD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035869783&doi=10.1175%2f1520-0442%282001%29014%3c1129%3aRDACAD%3e2.0.CO%3b2&partnerID=40&md5=403faeb7d82afa4de8aca26fad80e721","A regional (2.5° × 2.5° resolved) diurnal (hourly) albedo climatology for low and midlatitudes is derived for each month from the 5 1/3-yr narrow-field-of-view data record obtained from the Earth Radiation Budget Satellite (ERBS). It is used in a quasi-operational diurnal interpolation/extrapolation procedure (DIEP) to calculate regional monthly means of the reflected shortwave radiation flux (RSR) from instantaneous albedo observations. This climatological approach (CDIEP) replaces the questionable assumption of diurnally constant cloud conditions made in the conventional DIEP by assuming a diurnal variation of cloudiness corresponding to the mean long-term diurnal variation of the planetary albedo. Validation of CDIEP, using the three-satellite Earth Radiation Budget Experiment (ERBE) data for December of 1986, indicates that on regional scales monthly time sampling errors for single satellite products are generally reduced but not completely removed in comparison with the currently applied diurnal model (EDIEP). On a global scale, rms errors are reduced by 16% and 28% for ERBE NOAA-10 and NOAA-9 monthly mean RSR. respectively. The efficiency of CDIEP is satisfactory by accounting for coherent diurnal variations of cloudiness, if present, and by reproducing the results obtained by EDIEP elsewhere. Applying CDIEP to the full-year record of ScaRaB-Meteor ERB measurements enables the analysis of its impact with regard to the varying local observation time of each month. The standard deviation between regional monthly means of the RSR calculated by CDIEP and EDIEP varies between less than 2 W m-2 and about 4 W m2-2 for high-noon and near-terminator time sampling conditions, respectively. On regional scales, time sampling errors with a 3 1/2-month period, induced by the orbit's precession, can be reduced, in particular for marine areas characterized by persistent stratocumulus, where the amplitude often exceeds 10 W m-2."
"35396477200;6603192233;7402401574;","The impact of the 1997/98 El Niño event on the Atlantic Ocean",2001,"10.1175/1520-0442(2001)014<1069:TIOTEN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035869785&doi=10.1175%2f1520-0442%282001%29014%3c1069%3aTIOTEN%3e2.0.CO%3b2&partnerID=40&md5=8ab9599782cc0145ea1aa20e404fe1c5","The El Niño-Southern Oscillation (ENSO) has far-reaching impacts on global climate via ""teleconnections"" associated with wavelike or other disturbances that are excited in the tropical Pacific. These teleconnections may influence the air-sea heat fluxes, either by altering the latent and sensible heat fluxes through a change in low-level wind speed or direction or by altering the degree of cloud cover and thus the radiation budget. The anomalous fluxes can generate sea surface temperature (SST) anomalies that can in turn feed back on the atmospheric circulation. These effects are explored for the 1997/98 ENSO event using a novel and powerful modeling technique in which a coupled ocean-atmosphere model (the U.K. Hadley Centre HadCM3 model) is forced to follow observed tropical Pacific SSTs using a strong thermal relaxation, while elsewhere the model is allowed to vary freely. This is an extension of previous studies in which the impact of ENSO was investigated using an atmospheric model coupled to an ocean mixed layer model. The authors focus on the impact of ENSO on the Atlantic Ocean. Model results are compared both with historical records of the Atlantic response to El Niño and with SST observations during the 1997/98 event. The model simulates well the warming of the tropical North Atlantic that is typical of El Niño events. In addition, it identifies a significant positive anomaly in the South Atlantic in the autumn of 1997/98 that was also observed and appears to be a feature of the Atlantic response to El Niño that has not previously been noted. The results suggest that many other large SST anomalies observed in the Atlantic during 1997/98 were not part of the response to El Niño."
"7402245653;7005265210;7004651463;6602147826;","Sources of global warming in upper ocean temperature during El Niño",2001,"10.1029/1999jc000130","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034932913&doi=10.1029%2f1999jc000130&partnerID=40&md5=8f03875f7b3d6291b4bd174ddb78e169","Global average sea surface temperature (SST) from 40° S to 60° N fluctuates ±0.3°C on interannual period scales, with global warming (cooling) during El Niño (La Niña). About 90% of the global warming during El Niño occurs in the tropical global ocean from 20° S to 20° N, half because of large SST anomalies in the tropical Pacific associated with El Niño and the other half because of warm SST anomalies occurring over ∼80% of the tropical global ocean. From examination of National Centers for Environmental Prediction [Kalnay et al., 1996] and Comprehensive Ocean-Atmosphere Data Set [Woodruff et al., 1993] reanalyses, tropical global warming during El Niño is associated with higher troposphere moisture content and cloud cover, with reduced trade wind intensity occurring during the onset phase of El Niño. During this onset phase the tropical global average diabatic heat storage tendency in the layer above the main pycnocline is 1-3 W m-2 above normal. Its principal source is a reduction in the poleward Ekman heat flux out of the tropical ocean of 2-5 W m-2. Subsequently, peak tropical global warming during El Niño is dissipated by an increase in the flux of latent heat to the troposphere of 2-5 W m-2, with reduced shortwave and longwave radiative fluxes in response to increased cloud cover tending to cancel each other. In the extratropical global ocean the reduction in poleward Ekman heat flux out of the tropics during the onset of El Niño tends to be balanced by reduction in the flux of latent heat to the troposphere. Thus global warming and cooling during Earth's internal mode of interannual climate variability arise from fluctuations in the global hydrological balance, not the global radiation balance. Since it occurs in the absence of extraterrestrial and anthropogenic forcing, global warming on decadal, interdecadal, and centennial period scales may also occur in association with Earth's internal modes of climate variability on those scales. Copyright 2001 by the American Geophysical Union."
"7006514964;6602229351;","The recent evolution of climate on venus",2001,"10.1006/icar.2000.6570","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0002976117&doi=10.1006%2ficar.2000.6570&partnerID=40&md5=a3dce0e2ab58288603fdf753d1fe044a","The present climate of Venus is controlled by an efficient carbon dioxide-water greenhouse effect and by the radiative properties of its global cloud cover. Both the greenhouse effect and clouds are sensitive to perturbations in the abundance of atmospheric water vapor and sulfur gases. Planetary-scale processes involving the release, transport, and sequestering of volatiles affect these abundances over time, driving changes in climate. We have developed a numerical model of the climate evolution of Venus. Atmospheric temperatures are calculated using a one-dimensional two-stream radiative-convective model that treats the transport of thermal infrared radiation in the atmosphere and clouds. These radiative transfer calculations are the first to utilize high-temperature, high-resolution spectral databases for the calculation of infrared absorption and scattering in Venus' atmosphere. We use a chemical/microphysical model of Venus' clouds to calculate changes in cloud structure that result from variations in atmospheric water and sulfur dioxide. Atmospheric abundances of water, sulfur dioxide, and carbon dioxide change under the influence of the exospheric escape of hydrogen, outgassing from the interior, and heterogeneous reactions with surface minerals. Radar images from the Magellan mission show that the surface of Venus has been geologically active on a global scale, yet its sparse impact cratering record is almost pristine. This geologic record on Venus is consistent with an epoch of rapid plains emplacement 600-1100 Myr ago. Our models show that intense volcanic outgassing of sulfur dioxide and water during this time would have resulted in the formation of massive sulfuric acid/water clouds and the cooling of the surface for 100-300 Myr. The thick clouds would have subsequently given way to high, thin water clouds as atmospheric sulfur dioxide was lost to reactions with the surface. Surface temperatures approaching 900 K would have been reached 200-500 Myr after the onset of volcanic resurfacing. Evolution to current conditions would have proceeded due to loss of atmospheric water at the top of the atmosphere, ongoing low-level volcanism, and the reappearance of sulfuric acid/water clouds. We find that the maintenance of sulfuric acid/water clouds on Venus today requires sources of outgassed sulfur active in the past 20-50 Myr, in contrast with the 1.9 Myr as determined from geochemical arguments alone (B. Fegley and R. G. Prinn 1989, Nature337, 55-58). © 2001 Academic Press."
"7402205043;56962915800;","A coupled modeling study of the seasonal cycle of the Pacific cold tongue. Part I: Simulation and sensitivity experiments",2001,"10.1175/1520-0442(2001)014<0765:ACMSOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035284321&doi=10.1175%2f1520-0442%282001%29014%3c0765%3aACMSOT%3e2.0.CO%3b2&partnerID=40&md5=5926b02aed049b892f7588225af6d01f","A coupled tropical ocean-atmosphere model that fills the gap between anomalous coupled models and fully coupled general circulation models is described. Both the atmosphere and ocean are represented by two and one-half layer primitive equation models, which accentuate the physical processes in the oceanic mixed layer and atmospheric boundary layer. The two media are coupled through both momentum and heat flux exchanges without explicit flux correction. The coupled model, driven by solar radiation, reproduces realistic seasonal cycles of the mixed layer temperature, currents, and depth, and the surface winds and rainfall in the tropical Pacific. The model results indicate that the equatorial westward phase propagation of the annual warming is primarily caused by zonal temperature advection and downward solar radiation modified by clouds, whereas the wind-evaporation-SST feedback plays a minor role. The meridional wind component appears to have a stronger impact than the zonal wind component on the seasonal cycle of the eastern Pacific cold tongue, because the cross equatorial winds have stronger annual variation, which is more effective in regulation of SST through changing surface evaporation and mixed layer entrainment. The annual variation of the solar forcing is shown to have a significant impact on the long-term mean state. Without the seasonal cycle forcing, the western Pacific warm pool would shift eastward and the latitudinal climate asymmetry in the eastern Pacific would be stronger."
"57199923500;7102791212;7004372835;6602856875;7201990763;","Some results relevant to the discussion of a possible link between cosmic rays and the Earth's climate",2001,"10.1029/2000JD900589","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035091198&doi=10.1029%2f2000JD900589&partnerID=40&md5=8e689648a175a4097499a49a27cad632","Based on a 16-year observation period (1980-1995), it was claimed recently that Earth's climate was linked to variations in the flux of cosmic rays penetrating into the atmosphere via their postulated effect on global cloud cover. Data from three independent studies yield information relevant to the ongoing discussion of the likelihood of the existence of such a link. (1) Model calculations show that the relative change in the ion production rate from a solar maximum to a solar minimum is of the same order as, or even greater than, the corresponding change in global cloud cover. (2) However, the smoothed combined flux of 10Be and 36Cl at Summit, Greenland, from 20-60 kyr B.P. (proportional to the geomagnetically modulated cosmic ray flux) is unrelated to the corresponding δ18O and CH4 data (interpreted as supraregional climate proxies). (3) Furthermore, although a comparison of the incoming neutron flux with cloud cover in Switzerland over the last 5 decades shows a significant correlation at times during the 1980s and 1990s, this does not occur during the rest of the period. Copyright 2001 by the American Geophysical Union."
"6602853276;7003538476;7005262614;","Laboratory investigation of possible ice nucleation by ionizing radiation in pure water at tropospheric temperatures",2001,"10.1029/2000JD900670","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035085534&doi=10.1029%2f2000JD900670&partnerID=40&md5=9e6c4cb66c7cfc0c9b797654a6edf71e","A variety of mechanisms have been proposed to explain observed correlations between tropospheric climate variables and cosmic ray flux levels. The most direct hypothesis involves the formation of ice nuclei along ion tracks formed when cosmic rays pass through cloud water droplets. To test this hypothesis, we performed nucleation studies of a single water droplet undergoing repeated linear cooling cycles to -40°C with and without a radioactive source in the vicinity of the drop. A comparison of the distributions of nucleation temperatures obtained with and without a source of 5.3 MeV α-particles present supports the null hypothesis that ionization tracks do not act as nucleation sites. In both cases we observe mean nucleation temperatures of -34.5°C consistent with previous studies of homogeneous nucleation. Copyright 2001 by the American Geophysical Union."
"7005171879;7006303509;7410041005;","Parameterization of the radiative properties of midlatitude high and middle level clouds",2001,"10.1029/2000GL012236","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035864661&doi=10.1029%2f2000GL012236&partnerID=40&md5=30611e3f6b44ce8b59acb1f7bd3769a8","The clouds of the middle and upper troposphere are difficult to treat in models because of their variable optical properties. Based on extensive cirrus, altostratus, and altocumulus cloud remote sensing measurements and model simulations, we offer parameterizations of visible optical depth and infrared layer emittance as functions of both cloud temperature and vertical thickness to facilitate climate modeling research. We find significant differences in the emittance relations that depend on cloud phase, but quite similar optical depth versus emittance relations. In comparison to previous midlatitude cirrus results, our findings lead to lower atmospheric heating rates."
"7409080503;6603742681;","Quantifying uncetrainties in detemining SW cluod rediative forcing and cloud absorption due to variability in atmospheric conditions",2001,"10.1175/1520-0469(2001)058<0376:QUIDSC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035864514&doi=10.1175%2f1520-0469%282001%29058%3c0376%3aQUIDSC%3e2.0.CO%3b2&partnerID=40&md5=48f53163641e596b523bb32c63c96eb5","The concept of cloud radiative forcing (CRF) has been widely employed in studying the effects of clouds on the earth's radiation budget and climate. CRF denotes, in principle, the net influence of cloud alone on the radiation budget of a system. In practice, however, observational determination of CRF is fraught with uncertainties due to factors other than cloud that induce changes in atmospheric background conditions. The most notable variables include aerosol, water vapor, and the data sampling scheme. The impact of these factors on the derivation of CRF and cloud absorption is investigated here by means of modeling and analysis of multiple datasets. Improved estimation of CRF is attempted at the top of the atmosphere (TOA) and at the surface from spatially and temporally collocated ground and satellite measurements for broadband shortwave fluxes. Satellite data employed include pixel measurements from ERBE (1988-90), ScaRaB (1994-95), and CERES (1998), as well as surface data acquired across the Canadian radiation network, the ARM Central Facility site in Oklahoma, the US/NOAA SURFRAD networks, and the world BSRN (WMO) networks. It is found that surface CRF is much more susceptible to the variability in background conditions than TOA CRF. Selection of overly clear sky conditions often leads to significant overestimation of surface CRF, but TOA CRF remains intact or only slightly affected. As a result, the ratio of CRF at the surface and TOA is prone to overestimation. With careful treatments of these effects, the CRF ratio turns out to vary mostly between 0.9 and 1.1 implying approximately the same magnitude of atmospheric absorption under clear-sky and cloudy-sky conditions."
"7005231450;7005591860;7003684963;7005513582;9845516300;","Climates of the twentieth and twenty-first centuries simulated by the NCAR Climate System Model",2001,"10.1175/1520-0442(2001)014<0485:COTTAT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035866106&doi=10.1175%2f1520-0442%282001%29014%3c0485%3aCOTTAT%3e2.0.CO%3b2&partnerID=40&md5=fe081cf45526e88a9c539517040dacc8","The Climate System Model, a coupled global climate model without ""flux adjustments"" recently developed at the National Center for Atmospheric Research, was used to simulate the twentieth-century climate using historical greenhouse gas and sulfate aerosol forcing. This simulation was extended through the twenty-first century under two newly developed scenarios, a business-as-usual case (ACACIA-BAU, CO2 ≈ 710 ppmv in 2100) and a CO2 stabilization case (STA550, CO2 ≈ 540 ppmv in 2100). Here we compare the simulated and observed twentieth-century climate, and then describe the simulated climates for the twenty-first century. The model simulates the spatial and temporal variations of the twentieth-century climate reasonably well. These include the rapid rise in global and zonal mean surface temperatures since the late 1970s. the precipitation increases over northern mid- and high-latitude land areas. ENSO-induced precipitation anomalies, and Pole-midlatitude oscillations (such as the North Atlantic oscillation) in sea level pressure fields. The model has a cold bias (2°-6°C) in surface air temperature over land. overestimates of cloudiness (by 10%-30%) over land, and underestimates of marine stratus clouds to the west of North and South America and Africa. The projected global surface warming from the 1990s to the 2090s is ∼1.9°C under the BAU scenario and ∼1.5°C under the STA550 scenario. In both cases, the midstratosphere cools due to the increase in CO2, whereas the lower stratosphere warms in response to recovery of the ozone layer. As in other coupled models, the surface warming is largest at winter high latitudes (≥5.0°C from the 1990s to the 2090s) and smallest (∼1.0°C) over the southern oceans, and is larger over land areas than ocean areas. Globally averaged precipitation increases by ∼3.5% (3.0%) from the 1990s to the 2090s in the BAU (STA550) case. In the BAU case, large precipitation increases (up to 50%) occur over northern mid- and high latitudes and over India and the Arabian Peninsula. Marked differences occur between the BAU and STA550 regional precipitation changes resulting from inter-decadal variability. Surface evaporation increases at all latitudes except for 60°-90°S. Water vapor from increased tropical evaporation is transported into mid- and high latitudes and returned to the surface through increased precipitation there. Changes in soil moisture content are small (within ±3%). Total cloud cover changes little, although there is an upward shift of midlevel clouds. Surface diurnal temperature range decreases by about 0.2°-0.5°C over most land areas. The 2-8-day synoptic storm activity decreases (by up to 10%) at low latitudes and over midlatitude oceans, but increases over Eurasia and Canada. The cores of subtropical jets move slightly up-and equatorward. Associated with reduced latitudinal temperature gradients over mid- and high latitudes, the wintertime Ferrel cell weakens (by 10%-15%). The Hadley circulation also weakens (by ∼10%), partly due to the upward shift of cloudiness that produces enhanced warming in the upper troposphere."
"7004279605;7005215578;6507002063;","A class of nonhydrostatic global models",2001,"10.1175/1520-0469(2001)058<0349:ACONGM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035864517&doi=10.1175%2f1520-0469%282001%29058%3c0349%3aACONGM%3e2.0.CO%3b2&partnerID=40&md5=13c6d91dc5f6d957118247927e155165","A Cartesian, small- to mesoscale nonhydrostatic model is extended to a rotating mountainous sphere, thereby dispensing with the traditional geophysical simplifications of hydrostaticity, gentle terrain slopes, and weak rotation. The authors discuss the algorithmic design, relative efficiency, and accuracy of several different variants (hydrostatic, nonhydrostatic, implicit, explicit, elastic, anelastic, etc.) of the global model and prepare the ground for a future ""global cloud model"" -a research tool to study effects of small- and mesoscale phenomena on global flows and vice versa. There are two primary threads to the discussion: (a) presenting a novel semi-implicit anelastic global dynamics model as it naturally emerges from a small-scale dynamics model, and (b) demonstrating that nonhydrostatic anelastic global models derived from small-scale codes adequately capture a broad range of planetary flows while requiring relatively minor overhead due to the nonhydrostatic formulation of the governing equations. The authors substantiate their theoretical discussions with a detailed analysis of numerous simulations of idealized global orographic flows and climate states."
"7006331431;56676874900;7004436918;","A new satellite deep convective ice index for tropical climate monitoring: Possible implications for existing oceanic precipitation data sets",2001,"10.1029/2000GL011892","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035862097&doi=10.1029%2f2000GL011892&partnerID=40&md5=3e5fedc8909b63fbf3d71e510fe16218","The tropical atmosphere is continually overturning, with deep moist convective cloud systems exporting energy from the subcloud layer and depositing it in the upper troposphere. A new satellite index of this deep convective activity is based upon measurements of large ice particles in the upper portions of tropical convective complexes. This 20-year record reveals a strong signal of the El Niño Southern Oscillation (ENSO), with 10 to 15% upward (downward) swings in the deep convective index during El Niño (La Niña). Warming of tropical sea surface temperatures (SST), whether from anthropogenically-produced greenhouse gases or natural climate variability, is expected to be associated with more convective overturning of the atmosphere. While other tropical precipitation climatologies vary dramatically in their support of this relationship, the present deep convective ice (DCI) index shows a strong correlation between interannual variations of tropical convection and SST."
"7003684963;7005513582;7006705919;7005524881;","Improvements to the NCAR CSM-1 for transient climate simulations",2001,"10.1175/1520-0442(2001)014<0164:ITTNCF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035863375&doi=10.1175%2f1520-0442%282001%29014%3c0164%3aITTNCF%3e2.0.CO%3b2&partnerID=40&md5=07ae3c4ca3ebcaca0b49357bd8ce4b9f","Improvements to the NCAR Climate System Model, CSM-1, primarily for transient climate forcing simulations, are discussed. The impact of the individual changes is assessed through atmosphere-land or ocean-ice experiments, and through short coupled simulations. A 270-yr control simulation has been performed using the model with all of the changes, defined as CSM-1.3. Trace gas concentrations appropriate for 1870 were used and the model produced a stable surface climate with less deep ocean drift than CSM-1. Changing the aerodynamic roughness length of sea ice to a value appropriate for first year ice reduced the deep ocean salinity trend by a factor of 100 and error in the transport by the Antarctic circumpolar current by 50% (60 × 106 m3 s-1). Three new features were added to the Community Climate Model, version 3 (CCM3), which is the atmospheric component of CSM-1. These additions were N2O, CH4, CFC11, and CFC12 as prognostic tracers and the oxidation of CH4 to form water vapor; a prognostic cloud water formulation; and direct radiative effects of sulfate aerosols from a sulfate chemistry model (either online or using previously calculated three-dimensional aerosol loadings). Although these features represent substantial changes to the CCM3 formulation, allowing greatly improved flexibility for climate change experiments, they have relatively modest impact on the control simulation."
"6701354598;6507084504;7004511627;","Trends in low and high cloud boundaries and errors in height determination of cloud boundaries",2001,"10.1175/1520-0477(2001)082<1941:TILAHC>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042526858&doi=10.1175%2f1520-0477%282001%29082%3c1941%3aTILAHC%3e2.3.CO%3b2&partnerID=40&md5=16fd9532fdaa0ed4c1e74d13ca807e0d","Clouds are important to climate and climate trends. To determine trends in cloud-base heights and cloud-top heights, the Comprehensive Aerological Reference Data Set (CARDS) and the method of Chernykh and Eskridge are used to diagnose cloud base, top, and amount. Trends in time series of cloud bases and tops at 795 radiosonde stations from 1964 to 1998 are presented. It was found that trends in cloud-base height and cloud-top height are seasonally dependent and a function of cloud cover amount. There was a small increase in multilayer cloudiness in all seasons. Geographical distributions of decadal changes of cloud bases and tops were spatially nonuniform and depended upon the season. To estimate the errors made in calculating the heights of cloud boundaries, an analysis was made of the response of the thermistors and hygristors. Thermistors and hygristors are linear sensors of the first order. From this it is shown that the distance between calculated inflection points (cloud boundaries) of observed and true values is exactly equal to the time constant of the sensor times the balloon speed. More accurate cloud boundaries can be determined using this finding."
"7102505167;","Estimating atmospheric turbidity from climate data",2001,"10.1016/S1352-2310(00)00277-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035238805&doi=10.1016%2fS1352-2310%2800%2900277-6&partnerID=40&md5=b8592abba4beb6b45340c9dc073ba9d0","Aerosols have several important influences on the climate system. Among the more important of these are their roles in absorbing and scattering radiation, and as condensation nuclei in cloud-forming processes. Despite their importance, knowledge of their spatial and temporal variability and, in turn, their influence on climate, is incomplete. Constraints associated with conventional approaches to measuring atmospheric turbidity - including the requirements for clear skies and costly equipment - have contributed to a paucity of turbidity data. This paper presents a methodology for estimating atmospheric turbidity from readily available surface-weather data, regardless of cloud cover. Using a high-resolution spectral radiation model, clear-sky beam irradiance is parameterized as a function of atmospheric attenuation processes, including scattering and absorption by aerosols. The model is integrated over the day to obtain an expression for estimating potential daily clear-sky beam irradiation. Turbidity can then be estimated by forcing the model with monthly averaged climate data. The methodology can be applied at any location where the requisite climate data are available and therefore holds promise for a more complete, and possibly global, climatology of aerosols.Aerosols have several important influences on the climate system. Among the more important of these are their roles in absorbing and scattering radiation, and as condensation nuclei in cloud-forming processes. Despite their importance, knowledge of their spatial and temporal variability and, in turn, their influence on climate, is incomplete. Constraints associated with conventional approaches to measuring atmospheric turbidity - including the requirements for clear skies and costly equipment - have contributed to a paucity of turbidity data. This paper presents a methodology for estimating atmospheric turbidity from readily available surface-weather data, regardless of cloud cover. Using a high-resolution spectral radiation model, clear-sky beam irradiance is parameterized as a function of atmospheric attenuation processes, including scattering and absorption by aerosols. The model is integrated over the day to obtain an expression for estimating potential daily clear-sky beam irradiation. Turbidity can then be estimated by forcing the model with monthly averaged climate data. The methodology can be applied at any location where the requisite climate data are available and therefore holds promise for a more complete, and possibly global, climatology of aerosols. Copyright (C) 2000 Elsevier Science B.V."
"7101962277;35615376800;","Alpine cloud climatology using long-term NOAA-AVHRR satellite data",2001,"10.1007/s007040170044","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035020103&doi=10.1007%2fs007040170044&partnerID=40&md5=850e69b9f79416ea55bd7df13747a50c","Three different climates have been identified by our evaluation of AVHRR (Advanced Very High Resolution Radiometer) data using APOLLO (AVHRR Processing scheme Over Land, Clouds and Ocean) for a five-years cloud climatology of the Alpine region. The cloud cover data from four layers were spatially averaged in boxes of 15km by 14km. The study area only covers 540km by 560km. but contains regions with moderate, Alpine and Mediterranean climate. Data from the period July 1989 until December 1996 have been considered. The temporal resolution is one scene per day, the early afternoon pass, yielding monthly means of satellite derived cloud coverages 5% to 10% above the daily mean compared to conventional surface observation. At non-vegetated sited the cloudiness is sometimes significantly overestimated. Averaging high resolution cloud data seems to be superior to low resolution measurements of cloud properties and averaging is favourable in topographical homogeneous regions only. The annual course of cloud cover reveals typical regional features as foehn or temporal singularities as the so-called Christmas thaw. The cloud cover maps in spatially high resolution show local luff/lee features which outline the orography. Less cloud cover is found over the Alps than over the forelands in winter, an accumulation of thick cirrus is found over the High Alps and an accumulation of thin cirrus north of the Alps."
"7201485519;7004764167;35509639400;24322005900;","Combining ERBE and ISCCP data to assess clouds in the Hadley Centre, ECMWF and LMD atmospheric climate models",2001,"10.1007/s003820100157","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034791589&doi=10.1007%2fs003820100157&partnerID=40&md5=003c2a1bd7a7ddf5feda5ff8033fed3f","This study compares radiative fluxes and cloudiness fields from three general circulation models (the HadAM4 version of the Hadley Centre Unified model, cycle 16r2 of the ECMWF model and version LMDZ 2.0 of the LMD GCM), using a combination of satellite observations from the Earth Radiation Budget Experiment (ERBE) and the International Satellite Cloud Climatology Project (ISCCP). To facilitate a meaningful comparison with the ISCCP C1 data, values of column cloud optical thickness and cloud top pressure are diagnosed from the models in a manner consistent with the satellite view from space. Decomposing the cloud radiative effect into contributions from low-medium- and high-level clouds reveals a tendency for the models' low-level clouds to compensate for underestimates in the shortwave cloud radiative effect caused by a lack of high-level or mid-level clouds. The low clouds fail to compensate for the associated errors in the longwave. Consequently, disproportionate errors in the longwave and shortwave cloud radiative effect in models may be taken as an indication that compensating errors are likely to be present. Mid-level cloud errors in the mid-latitudes appear to depend as much on the choice of the convection scheme as on the cloud scheme. Convective and boundary layer mixing schemes require as much consideration as cloud and precipitation schemes when it comes to assessing the simulation of clouds by models. Two distinct types of cloud feedback are discussed. While there is reason to doubt that current models are able to simulate potential 'cloud regime' type feedbacks with skill, there is hope that a model capable of simulating potential 'cloud amount' type feedbacks will be achievable once the reason for the remaining differences between the models are understood."
"7410041005;7005171879;","Cloud type and macrophysical property retrieval using multiple remote sensors",2001,"10.1175/1520-0450(2001)040<1665:CTAMPR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035482661&doi=10.1175%2f1520-0450%282001%29040%3c1665%3aCTAMPR%3e2.0.CO%3b2&partnerID=40&md5=bb636fdf96d50b91293d9d7d94aacc2c","A cloud detection algorithm based on ground-based remote sensors has been developed that can differentiate among various atmospheric targets such as ice and water clouds, virga, precipitation, and aerosol layers. Standard cloud type and macrophysical properties are identified by combining polarization lidar, millimeter-wave radar, infrared radiometer, and dual-channel microwave radiometer measurements. These algorithms are applied to measurements collected during 1998 from the Atmospheric Radiation Measurement Program Cloud and Radiation Test Bed site in north-central Oklahoma. The statistical properties of clouds for this year are presented, illustrating how extended-time remote sensing datasets can be converted to cloud properties of concern to climate research."
"7501855361;16637291100;","Spatial variability of the sea-ice radiation budget and its effect on aggregate-area fluxes",2001,"10.3189/172756401781818130","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035657734&doi=10.3189%2f172756401781818130&partnerID=40&md5=068c47572344757b2d2874fc1227d5e0","The spatial and temporal variability of surface, cloud and radiative properties of sea ice are examined using new satellite-derived products. Downwelling short- and longwave fluxes exhibit temporal correlation over about 180 days, but cloud optical depth and cloud fraction show almost no correlation over time. The spatial variance of surface properties is shown to increase much less rapidly than that of cloud properties. The effect of small-scale inhomogeneity in surface and cloud properties on the calculation of radiative fluxes at ice- and climate-model gridscales is also investigated. Annual mean differences between gridcell fluxes computed from average surface and cloud properties and averages of pixel-by-pixel fluxes are 9.46% for the downwelling shortwave flux and -7.04% for the longwave flux. Therefore, using mean surface and cloud properties to compute surface radiative fluxes in a gridcell results in an over-estimate of the shortwave flux and an underestimate of the longwave flux. Model sensitivity studies show that such biases may result in substantial errors in modeled ice thickness. Clearly, the sub-gridscale inhomogeneity of surface and atmospheric properties must be considered when estimating aggregate-area fluxes in sea-ice and climate models."
"35572096100;7007108728;7006061457;25941200000;","Microphysical properties of continental clouds from in situ measurements",2001,"10.1256/smsqj.57613","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035386916&doi=10.1256%2fsmsqj.57613&partnerID=40&md5=7d024937d94584b3c0023e25fed6b591","It is important to gain knowledge about the microphysical characteristics of continental clouds in order to properly understand their formation, their radiative properties and their ability to produce precipitation. Satellites to remotely sense cloud properties, and cloud interactions with aircraft that fly through them require knowledge of cloud microphysics. Moreover, numerical simulations of global climate are sensitive to small systematic changes in cloud optical properties, but very few large datasets are available that document the characteristics of continental clouds. This paper summarizes 9 × 104 km of in-cloud measurements made by the Central Aerological Observatory over the former USSR during 1977-84. Statistical characteristics of total water content (W), extinction coefficient (β), effective diameter (Deff) and effective concentration (Neff) are summarized as functions of temperature and cloud type, for measurements archived at 700 m horizontal resolution. The effect of threshold sensitivity, or cloud definition, on the statistical distributions is discussed. Decreases of W, β and Neff with colder temperatures are consistent with our general knowledge of cloud formation. For all temperature intervals and cloud types, correlations between pairs of W, β and Deff are, too small thereby barring any hope of simple linear parametrizations. Differences in W, β, Deff and Neff for the various cloud types indicate changes in cloud formation mechanisms. These data can assist in verification studies of cloud parametrization schemes in general-circulation models, numerical weather-prediction models, and cloud-resolving models. The problems of cloud type, scale averaging, variability over a model grid cell, distribution of water between the liquid and ice phase, and the lumping together of precipitating and non-precipitating clouds must be considered in these studies."
"6602806333;6505967243;","The use of nwp model surface temperatures in cloud detection from satellite",2001,"10.1080/01431160118309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035840378&doi=10.1080%2f01431160118309&partnerID=40&md5=dfd2d84b89148ba547d86489ac1dd481","An increasing number of satellite cloud detection methods include the use of Numerical Weather Prediction model (NWP) surface temperatures as a threshold for the thermal infrared cloud detection test. The NWP model surface temperature and the satellite apparent brightness temperature are assumed to correlate well for clear sky. Investigations over Europe in April 1997 indicate that the correlation over land is highly dependent on location and time of day. In this paper, it is shown that this variation of the correlation has a distinct impact on the quality of the infrared cloud detection test. As a result, cloud cover fractions which are retrieved using this thermal infrared test are biased by this effect. This can have serious impact on the quality of cloud climatologies, especially with respect to the diurnal variation of cloud cover fraction. A new method is introduced to equalize the quality of the infrared cloud detection test throughout the day. Threshold values are allowed to be smaller than commonly used and therefore the quality of the infrared test is improved. The method may be applied in both climate research and near real-time processing. © 2001 Taylor & Francis Ltd."
"7102237893;","Shortwave flux from satellite-measured radiance: A theoretical study over marine boundary layer clouds",2001,"10.1175/1520-0450(2001)040<2144:sffsmr>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035695471&doi=10.1175%2f1520-0450%282001%29040%3c2144%3asffsmr%3e2.0.co%3b2&partnerID=40&md5=e3dcaeba325c19cf5392f92877184075","Earth radiation budget measurements, important to climate monitoring and to validating climate models, require that radiances measured by satellite instruments be converted to hemispherical flux. This paper examines that problem theoretically, using inhomogeneous cloud models constructed from Landsat scenes of marine boundary layer clouds. The spherical harmonics discrete ordinates method (SHDOM) code is applied to the model scenes to compute full two-dimensional radiation fields, which then simulate measured radiances. Inversion to flux is performed by several different methods, including plane-parallel table lookup and empirical angular distribution models with three different ways of determining scene identification, to examine error sources and relative magnitudes. Using a simple plane-parallel table lookup results in unacceptably large flux bias errors of 11%-60%, depending on the orbital viewing geometry. This bias can be substantially reduced, to no more than 6%, by using empirical angular distribution models. Further improvement, to no more than 2% flux bias error, is obtained if known biases in optical-depth retrievals are taken into account when building the angular models. Last, the bias can be further reduced to a fraction of a percent using scene identification based on multiple views of the same area. There are limits, however, to the reduction in the instantaneous error with this approach. Trends in the flux error are also identified, in particular an equator-to-pole trend in the flux bias. Given the importance of satellite measurements for determining heat transport from equator to pole, this consistent bias should be kept in mind, and efforts should be made to reduce it in the future."
"7003279098;6603950324;55739684700;","Dimythylsulphide production in the subantarctic southern ocean under enhanced greenhouse conditions",2001,"10.1034/j.1600-0889.2001.01244.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034868496&doi=10.1034%2fj.1600-0889.2001.01244.x&partnerID=40&md5=930ee19cb137c2643f19b66d7070a0d8","Dimethylsulphide (DMS) is an important sulphur-containing trace gas produced by enzymatic cleavage of its precursor compound, dimethylsulphoniopropionate (DMSP), which is released by marine phytoplankton in the upper ocean. After ventilation to the atmosphere, DMS is oxidised to form sulphate aerosols which in the unpolluted marine atmosphere are a major source of cloud condensation nuclei (CCN). Because the micro-physical properties of clouds relevant to climate change are sensitive to CCN concentration in air, it has been postulated that marine sulphur emissions may play a rôle in climate regulation. The Subantarctic Southern Ocean (41-53°S) is relatively free of anthropogenic sulphur emissions, thus sulphate aerosols will be mainly derived from the biogenic source of DMS, making it an ideal region in which to evaluate the DMS-climate regulation hypothesis. We have extended a previous modelling analysis of the DMS cycle in this region by employing a coupled general circulation model (CGCM) which has been run in transient mode to provide a more realistic climate scenario. The CGCM output provided meteorological data under the IPCC/IS92a radiative forcing scenario. A DMS production model has been forced with the CGCM climate data to simulate the trend in the sea-to-air DMS flux for the period 1960 to 2080, corresponding to equivalent CO2 tripling relative to pre-industrial levels. The results confirm a minor but non-negligible increase in DMS flux in this region, in the range +1% to +6% predicted over the period simulated. Uncertainty analysis of the DMS model predictions have confirmed the positive sign for the change in DMS flux, that is a negative DMS feedback on warming."
"7005548544;7201844203;7006957668;","Does the Earth Have an Adaptive Infrared Iris?",2001,"10.1175/1520-0477(2001)082<0417:DTEHAA>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001463732&doi=10.1175%2f1520-0477%282001%29082%3c0417%3aDTEHAA%3e2.3.CO%3b2&partnerID=40&md5=bc1ec1b24aa478858141111ed9507dba","Observations and analyses of water vapor and clouds in the Tropics over the past decade show that the boundary between regions of high and low free-tropospheric relative humidity is sharp, and that upper-level cirrus and high free-tropospheric relative humidity tend to coincide. Most current studies of atmospheric climate feedbacks have focused on such quantities as clear sky humidity, average humidity, or differences between regions of high and low humidity, but the data suggest that another possible feedback might consist of changes in the relative areas of high and low humidity and cloudiness. Motivated by the observed relation between cloudiness (above the trade wind boundary layer) and high humidity, cloud data for the eastern part of the western Pacific from the Japanese Geostationary Meteorological Satellite-5 (which provides high spatial and temporal resolution) have been analyzed, and it has been found that the area of cirrus cloud coverage normalized by a measure of the area of cumulus coverage decreases about 22% per degree Celsius increase in the surface temperature of the cloudy region. A number of possible interpretations of this result are examined and a plausible one is found to be that cirrus detrainment from cumulus convection diminishes with increasing temperature. The implications of such an effect for climate are examined using a simple two-dimensional radiative-convective model. The calculations show that such a change in the Tropics could lead to a negative feedback in the global climate, with a feedback factor of about -1.1, which if correct, would more than cancel all the positive feedbacks in the more sensitive current climate models. Even if regions of high humidity were not coupled to cloudiness, the feedback factor due to the clouds alone would still amount to about -0.45, which would cancel model water vapor feedback in almost all models. This new mechanism would, in effect, constitute an adaptive infrared iris that opens and closes in order to control the Outgoing Longwave Radiation in response to changes in surface temperature in a manner similar to the way in which an eye's iris opens and closes in response to changing light levels. Not surprisingly, for upper-level clouds, their infrared effect dominates their shortwave effect. Preliminary attempts to replicate observations with GCMs suggest that models lack such a negative cloud/moist areal feedback."
"7004335851;56899142800;6507750380;7004617100;7102295175;","Multi-year simulations using a regional-climate model over the Iberian Peninsula: Current climate and doubled CO2 scenario",2001,"10.1256/smsqj.57510","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035390237&doi=10.1256%2fsmsqj.57510&partnerID=40&md5=fe776d987d4c8c97e2ead1c8bbbef9b7","In order to analyse the regional climate sensitivity in the Iberian Peninsula and surrounding areas to the global change related to an increase of CO2, two simulations (current climate and scenario) are performed using a regional-climate model (RCM) one-way nested in a global circulation model (GCM). Both simulations cover a ten-year period. The results of the control simulation (current climate) are compared to a climatological database. RCM and GCM representations of the climate are realistic, but the RCM shows more detailed results. Following this, a statistical analysis of the differences between current climate and double CO2 scenario simulations is carried out considering both 2 m temperature and precipitation. The analysis shows a significant warming in seasonal averages and important differences in the 2 m temperature interannual variability. Especially important is the strong increase in interannual variability of precipitation found in winter and autumn. Relationships between anomalies of general circulation (500 hPa geopotential field) and surface temperature, precipitation and cloudiness are also analysed, showing an important effect of cloud cover anomalies over the 2 m temperature interannual variability."
"7102128820;7006698304;7007114756;","Comparison of ECMWF winter-season cloud fraction with radar-derived values",2001,"10.1175/1520-0450(2001)040<0513:COEWSC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035270027&doi=10.1175%2f1520-0450%282001%29040%3c0513%3aCOEWSC%3e2.0.CO%3b2&partnerID=40&md5=18fefa667b54d144d9a4c94926c350b4","Of great importance for the simulation of climate using general circulation models is their ability to represent accurately the vertical distribution of fractional cloud amount. In this paper, a technique to derive cloud fraction as a function of height using ground-based radar and lidar is described. The relatively unattenuated radar detects clouds and precipitation throughout the whole depth of the troposphere, whereas the lidar is able to locate cloud base accurately in the presence of rain or drizzle. From a direct comparison of 3 months of cloud fraction observed at Chilbolton, England, with the values held at the nearest grid box of the European Centre for Medium-Range Forecasts (ECMWF) model it is found that, on average, the model tends to underpredict cloud fraction below 7 km and considerably overpredict it above. The difference below 7 km can in large part be explained by the fact that the model treats snow and ice cloud separately, with snow not contributing to cloud fraction. Modifying the model cloud fraction to include the contribution from snow (already present in the form of fluxes between levels) results in much better agreement in mean cloud fraction, frequency of occurrence, and amount when present between 1 and 7 km. This, together with the fact that both the lidar and the radar echoes tend to be stronger in the regions of ice clouds that the model regards as snow, indicates that snow should not be treated as radiatively inert by the model radiation scheme. Above 7 km, the difference between the model and the observations is partly due to some of the high clouds in the model being associated with very low values of ice water content that one would not expect the radar to detect. However, removal of these from the model still leaves an apparent overestimate of cloud fraction by up to a factor of 2. A tendency in the lowest kilometer for the model to simulate cloud features up to 3 h before they are observed is also found. Overall, this study demonstrates the considerable potential of active instruments for validating the representation of clouds in models."
"7005171879;7006303509;7410041005;35494005000;","Cloud and aerosol research capabilities at FARS: The Facility for Atmospheric Remote Sensing",2001,"10.1175/1520-0477(2001)082<1119:CAARCA>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000771623&doi=10.1175%2f1520-0477%282001%29082%3c1119%3aCAARCA%3e2.3.CO%3b2&partnerID=40&md5=a5537ef4e46bf3f6e0fc978495dc32ef","Since October 1987, the University of Utah Facility for Atmospheric Remote Sensing (FARS) has been applied to the probing of the atmosphere, concentrating on the study of high-level clouds. Regular FARS measurements, which currently total ∼3000 h of ruby lidar polarization data, have been directed toward basic cloud research, remote sensing techniques development, and to improving satellite cloud property retrieval methods and GCM predictions by providing climatologically representative cloud datasets and parameterizations. Although the initial studies involved mainly the ruby lidar, the facility has steadily evolved to include a range of visible, infrared, and microwave passive remote sensors, and state-of-the-art, high-resolution dual-wavelength scanning lidar and W-band Doppler radar systems. All three active systems display polarization diversity. In this paper are reviewed the specifications of FARS instrumentation and the research programs to which they have been applied. Four multiple remote sensor case studies of various cloud systems are presented to illustrate the research capabilities. Like a handful of similar sites elsewhere, such research centers dedicated to extended time observation programs have great potential for contributing to atmospheric monitoring and climate research."
"7005129538;7101835390;6602958963;","Mechanisms of sulphate aerosol production in clouds: Effect of cloud characteristics and season in the Indian region",2001,"10.1034/j.1600-0889.2001.01015.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034868683&doi=10.1034%2fj.1600-0889.2001.01015.x&partnerID=40&md5=9afb66a4ea21c2752dd179bf38cb34ab","Measurements made during the Indian Ocean Experiment (INDOEX) in 1998, indicate likely regional atmospheric effects of sulphate aerosol over India including the potential for cloud processing of SO2 to sulphate. Sulphate aerosol production in clouds was examined for cloud characteristics and pollutant concentrations typical of the Indian region, to assess the contribution of different mechanisms to sulphate formation. A simple model was formulated incorporating gas-liquid equilibria, gas-phase mass transfer, SO2 oxidation in the gas phase by OH radicals and in the aqueous phase by H2O2O3 and O2 catalysed by Fe3+ and Mn2+ in a cloud with uniformly sized drops. Sulphate formation was simulated in St/Sc Cu and Cb clouds using an initial pH of 6.5, likely to occur in this region, for cloud drop diameters of 10, 50 and 100 μm. The clouds were assumed to have nucleated on ammonium sulphate aerosols and contained reported background concentrations of these ions in clean rainwater over the Indian ocean. The simulations produced final cloud pHs of 4.5-5 and final sulphate concentrations of 25-90 μM, in agreement with the range of reported preliminary measurements. An examination of mass transfer effects showed that the characteristic diffusion times of H2O2 and SO2 were lower by a factor of 10 or more than the respective reaction times, indicating that mass transfer effects would not limit the rate of SVI formation under likely atmospheric conditions. Sulphate formation in St/Sc clouds was shown to likely be SO2 limited in July and H2O2 limited in January. In all cases, the gas phase reaction and the O2 reaction catalysed by Mn2+ and Fe3+ contributed less than 1% to the SVI produced. In St/Sc and Cu clouds, 85-96% of the SVI was from the H2O2 reaction. In Cb clouds about 60-75% of the SVI was from the H2O2 reaction and 25-41% from the O3 reaction. In Cb clouds, the short residence and the persistence of alkaline conditions in the earlier part of the cloud cycle, enhance the contribution of the O3 reaction to the greatest extent. If alkaline conditions were to persist throughout the cloud cycle (from cation chemistry not simulated in this model), the contribution of the O3 reaction to SVI could be further enhanced."
"35609833400;7005921461;6505678723;","Relationship between convective precipitation and cloud-to-ground lightning in the Iberian Peninsula",2001,"10.1175/1520-0493(2001)129<2998:RBCPAC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035656022&doi=10.1175%2f1520-0493%282001%29129%3c2998%3aRBCPAC%3e2.0.CO%3b2&partnerID=40&md5=819ddc6cacefa19082d9f8405731e833","The relationship between cloud-to-ground (CG) lightning and convective precipitation over the Iberian Peninsula during the warm season was analyzed. The database covered the period between 1992 and 1994 and the precipitation data from 68 meteorological observatories were used. Temporal and spatial scales of 1 month and 102 km2 were considered. Values of rain yield (defined as the ratio of convective precipitation to CG flash count over a common area) were centered around a mean value of ∼ 108 kilograms per flash (kg fl-1) but varied as a function of the climate regime, increasing from a mean value of 1.2 × 108 kg fl-1 for the semiarid region of the Iberian Peninsula to a mean value of 2.1 × 108 kg fl-1 for the humid region of the Iberian Peninsula. The correlation coefficients between convective precipitation and the CG flash count also varied with the climate regime. The correlation coefficient was higher for the semiarid zone (0.75) than for the humid one (0.65). These variations are physically consistent. Within each climate regime, rain yield (correlation) was lower (higher) in July than in June and August, although this result was probably an effect of convective precipitation, which is inflated by frontal precipitation. To test the stability and correlation associated with these results, a ""predicted"" convective precipitation for 1994 was calculated using the rain yields of 1992-93. The seasonal correlation coefficient between predicted and gauge-measured precipitation was 0.71."
"7102641791;35396805300;8068050600;35428937200;7006918513;","The potential impacts of climate variability and change on air pollution-related health effects in the United States",2001,"10.2307/3435010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035001594&doi=10.2307%2f3435010&partnerID=40&md5=2eb39c9c4e2de41799b62bd9a2d2d0da","Climate change may affect exposures to air pollutants by affecting weather, anthropogenic emissions, and biogenic emissions and by changing the distribution and types of airborne allergens. Local temperature, precipitation, clouds, atmospheric water vapor, wind speed, and wind direction influence atmospheric chemical processes, and interactions occur between local and global-scale environments. If the climate becomes warmer and more variable, air quality is likely to be affected. However, the specific types of change (i.e., local, regional, or global), the direction of change in a particular location (i.e., positive or negative), and the magnitude of change in air quality that may be attributable to climate change are a matter of speculation, based on extrapolating present understanding to future scenarios. There is already extensive evidence on the health effects of air pollution. Ground-level ozone can exacerbate chronic respiratory diseases and cause short-term reductions in lung function. Exposure to particulate matter can aggravate chronic respiratory and cardiovascular diseases, alter host defenses, damage lung tissue, lead to premature death, and possibly contribute to cancer. Health effects of exposures to carbon monoxide, sulfur dioxide, and nitrogen dioxide can include reduced work capacity, aggravation of existing cardiovascular diseases, effects on pulmonary function, respiratory illnesses, lung irritation, and alterations in the lung's defense systems. Adaptations to climate change should include ensuring responsiveness of air quality protection programs to changing pollution levels. Research needs include basic atmospheric science work on the association between weather and air pollutants; improving air pollution models and their linkage with climate change scenarios; and closing gaps in the understanding of exposure patterns and health effects."
"7404577357;35481796400;","Noctilucent clouds as possible indicators of global change in the mesosphere",2001,"10.1016/S0273-1177(01)80021-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035668332&doi=10.1016%2fS0273-1177%2801%2980021-1&partnerID=40&md5=a950b6372223a5430edd8b5db507f4ed","Noctilucent clouds (NLC) are ice clouds near the high-latitude mesopause region, occurring in summer. These clouds have been implicated as possible harbingers of permanent changes in the upper atmosphere. Their year-to-year variations have been characterized by a semi-quantitative index, the number of nights per season in which they were reported. In this paper we compare early studies of NLC year-to-year variability with data from the modern era, including observations from Europe, the USSR and North America. This review focuses on the possible influence on NLC of water vapor variability. We compare the noctilucent cloud time series, which indicate a strong upward trend in the 1964-1986 period, with changes expected of atmospheric water vapor at the mean height of the clouds (83 km). At this height, both methane-induced changes and 11-year solar-UV induced changes are expected to be the main forcings. Using the data available for surface methane and for solar Lyman-alpha fluxes, we estimate the water vapor changes due to methane oxidation, and to Lyman-α induced photodissociation of water vapor. For the periodic (10-year) component, the NLC time series was found to significantly correlate with Lyman-α flux data, for nearly all available multi-decadal NLC data sets. As first shown by Gadsden for the European data, the correlations are highest when the time lag of NLC following solar cycle minimum is two to three years. This result places into considerable doubt the hypothesis of direct solar Lyman-α control of NLC. Volcanism appears to have had a negligible influence, with the possible exception of the 1883 Krakatoa eruption. © 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved."
"57204257582;35547795500;7101860955;7004965009;7202617312;6701762102;","Long-term changes in the water quality of rainfall, cloud water and stream water from for moorland, forested and clear-felled catchments at Plynlimon, mid-Wales",2001,"10.5194/hess-5-459-2001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035197749&doi=10.5194%2fhess-5-459-2001&partnerID=40&md5=690770a23f598c1c707aece05958d16f","Long term changes in the water quality of rainfall, cloud water and stream waters draining acidic and acid sensitive moorland and forested catchments at Plynlimon, mid-Wales, are examined for the period 1983 to 2001. Atmospheric inputs of chloride and sulphate are influenced by the relative inputs of clean maritime and polluted land based air masses. There is no systematic increase or decrease over time for chloride and non-sea-salt sulphate. Rather, there is a decadal scale process possibly representative of the influence of the North Atlantic Oscillation that affects the maritime and pollution climate of the Atlantic seaboard of the UK. Over 17 years of study, there may be a small decrease in non-sea-salt sulphate of about 10 μ eq 1-1 and a small improvement in acid neutralising capacity of about 20 to 30 ieq 1-1 in rainfall. There is a clear improvement in cloud water chemistry with respect to pollutant components (ammonium, nitrate, non-sea-salt sulphate) and acidity (acid neutralising capacity improved by about 300 μeq 1-1) through the study period. Many of the changes in cloud water chemistry are similar to rainfall over the same period except the magnitude of change is larger for the cloud water. Within the streams, there is some evidence for reduction in acidity as reflected by acid neutralising capacity becoming less negative. For one stream, deforestation occured during the sampling period and this led to large increases in nitrate and smaller increases in aluminium midway through the study period. However, the climate and hydrological variability largely masked out other changes. The current analysis provides only a start to identifying trends for such a complex and variable environmental system. The need for strong statistical tools is emphasised to resolve issues of: (a) Hydrological induced water quality variability, (b) Changing soil and groundwater ""endmember"" chemistry contribution to the stream and (c) The non-linear patterns of change. Nonetheless, the analysis is enhanced by examining trends in chemistry for yearly averages and yearly average low catch and high catch rainfall and cloud water events as well as low and high flow stream chemistry. This approach allows trends to be examined within the context of endmember mixing."
"55423489000;7006033615;","Quantification of the influence of wind and cloud on the nocturnal urban heat island of a large city",2001,"10.1175/1520-0450(2001)040<0169:QOTIOW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035248148&doi=10.1175%2f1520-0450%282001%29040%3c0169%3aQOTIOW%3e2.0.CO%3b2&partnerID=40&md5=eb6ef026072cb73e0a273745e6548e9a","Analyses taken over all observed weather conditions of daily 0600 EST climate data from a network of monitoring stations in and around the large city of Melbourne, Australia, revealed a 20-yr mean urban heat island (UHI) value of 1.13°C. The UHI varied seasonally between summer (1.29°C), spring (1.25°C), autumn (1.02°C), and winter (0.98°C). Investigations undertaken with daily wind speed and cloud amount data enabled a detailed investigation of the relative importance of factors such as the turbulent and radiative exchanges on Melbourne's UHI. Analysis of variance and regression techniques were used to explore these processes and to predict the behavior of the UHI in numerical terms for mean seasonal and annual periods between 1972 and 1991. Over the 20-yr period, analyses of the association among Melbourne's UHI, wind, and cloud revealed that the UHI was inversely proportional to approximately the fourth root of both the wind speed and the cloud amount. This relationship explained more of the UHI variance during summer and the least variance during winter. Increases in the amount of cloud cover and in the frequency of wind speeds in excess of 2.0 m s-1 resulted in a statistically significant (95% confidence level) reduction in UHI magnitude. The influence of wind in limiting Melbourne's UHI magnitude was greatest during clear to near-clear sky conditions. Similarly increases in cloud were most restrictive to UHI development during calm to low wind speeds. Unlike most previous studies, the linear regression analysis presented here revealed that cloud was more limiting than the wind speed to UHI development for all seasons except summer. Contour plots of the UHI are presented for the various associations between each category of cloud and wind. These plots enable a clear visual presentation of the most to least favorable conditions for UHI intensity and development. The analyses indicate that low wind speeds and little or no cloud were typically associated with the largest UHI development. Eight octas of cloud and wind speeds in excess of 5.0 m s-1 were usually associated with modest (but still apparent) UHI development."
"57202245193;","Satellite-observed variability and trend in sea-ice extent, surface temperature, albedo and clouds in the Arctic",2001,"10.3189/172756401781818617","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035655714&doi=10.3189%2f172756401781818617&partnerID=40&md5=f2fd79a64d2ed19265c3e0f9379ea67d","Recent observations of a decreasing ice extent and a possible thinning of the ice cover in the Arctic make it imperative that detailed studies of the current Arctic environment are made, especially since the region is known to be highly sensitive to a potential change in climate. A continuous dataset of microwave, thermal infrared and visible satellite data has been analyzed for the first time to concurrently study in spatial detail the variability of the sea-ice cover, surface temperature, albedo and cloud statistics in the region from 1987 to 1998. Large warming anomalies during the last four years (i.e. 1995-98) are indeed apparent and spatially more extensive than previous years. The largest surface temperature anomaly occurred in 1998, but this was confined mainly to the western Arctic and the North American continent, while cooling occurred in other areas. The albedo anomalies show good coherence with the sea-ice concentration anomalies except in the central region, where periodic changes in albedo are observed, indicative of interannual changes in duration and areal extent of melt ponding and snow-free ice cover. The cloud-cover anomalies are more difficult to interpret, but are shown to be well correlated with the expected warming effects of clouds on the sea-ice surface. The results from trend analyses of the data are consistent with a general warming trend and an ice-cover retreat that appear to be even larger during the last dozen years than those previously reported."
"7003377229;35453054300;","A climate version of the regional atmospheric modeling system",2001,"10.1007/s007040170043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034996642&doi=10.1007%2fs007040170043&partnerID=40&md5=6fc7c3ef85bf71f9b1576e9b491c9a64","The Regional Atmospheric Modeling System (RAMS) has been widely used to simulate relatively short-term atmospheric processes. To perform full-year to multi-year model integrations, a climate version of RAMS (ClimRAMS) has been developed, and is used to simulate diurnal, seasonal, and annual cycles of atmospheric and hydrologic variables and interactions within the central United States during 1989. The model simulation uses a 200-km grid covering the conterminous United States, and a nested, 50-km grid covering the Great Plains and Rocky Mountain states of Kansas, Nebraska, South Dakota, Wyoming, and Colorado. The model's lateral boundary conditions are forced by six-hourly NCEP reanalysis products. ClimRAMS includes simplified precipitation and radiation sub-models, and representations that describe the seasonal evolution of vegetation-related parameters. In addition, ClimRAMS can use all of the general RAMS capabilities, like its more complex radiation sub-models, and explicit cloud and precipitation microphysics schemes. Thus, together with its nonhydrostatic and fully-interactive telescoping-grid capabilities, ClimRAMS can be applied to a wide variety of problems. Because of non-linear interactions between the land surface and atmosphere, simulating the observed climate requires simulating the observed diurnal, synoptic, and seasonal cycles. While previous regional climate modeling studies have demonstrated their ability to simulate the seasonal cycles through comparison with observed monthly-mean temperature and precipitation data sets, this study demonstrates that a regional climate model can also captured observed diurnal and synoptic variability. Observed values of daily precipitation and maximum and minimum screen-height air temperature are used to demonstrate this ability."
"55802246600;7006592026;55168941800;7006344866;24080667300;","Regional simulation of anthropogenic sulfur over East Asia and its sensitivity to model parameters",2001,"10.3402/tellusb.v53i2.16573","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034875630&doi=10.3402%2ftellusb.v53i2.16573&partnerID=40&md5=27b0dcb10bb5b501614837a585842d9b","We discuss a series of simulations of anthropogenic sulfur over East Asia with a SO2/SO2-4 chemistry-transport model driven in on-line mode by a regional climate model. Sensitivity to OH and H2O2 concentration, cloud parameters, SO2 dry deposition and emission strength is analyzed and the different components of the sulfur budget are examined. The SO2 and SO2-4 column burdens show pronounced variability at temporal scales from seasonal to synoptic and sub-daily, with SO2 and SO2-4 behaving differently due to the interplay of chemical conversion, removal and transport processes. Both SO2 and SO2-4 show marked spatial variability, with emission being the dominant term in regulating the SO2 spatial distribution. The atmospheric SO2 and SO2-4 amounts show close to a linear response to surface emission. Aqueous phase SO2 → SO2-4 conversion and wet removal are the primary factors that regulate the SO2-4 amounts, with dry deposition and gas phase SO2 → SO2-4 conversion being of secondary importance. Aqueous phase conversion and dry deposition are the dominant loss mechanisms for SO2. The model shows low sensitivity to variations in OH, H2O2, and cloud parameters, while the sensitivity to prescribed dry deposition velocity is more pronounced. Overall, our results are in line with previous modeling studies and with very limited available observations."
"7006393918;8304837900;7005941690;7005981420;7102811122;","The compact visible and infrared radiometer (COVIR) for earth and climate monitoring",2001,"10.1109/AERO.2001.931479","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034847743&doi=10.1109%2fAERO.2001.931479&partnerID=40&md5=a2eee6a1480058ab904b6f930f631d66","The Compact Visible and Infrared Radiometer (COVIR) is an imaging system being developed at the NASA Goddard Space Flight Center for use in earth and climate monitoring. The goals of this effort are to develop an imager that satisfies the radiometric demands of typical infrared and visible earth observations while providing a compact and low-cost instrument for small satellite missions. The infrared camera of COVIR is built around an uncooled microbolometer array detector whereas the visible camera is built around a CCD linear detector array. Together these two cameras provide calibrated imagery of clouds, land, and sea at infrared wavelengths of 10.8 um, 12.0 um, and 3.7 um along with visible wavelengths of 870 nm, 670 nm, 550 nm, and 440 nm and stereoscopic retrieval of cloud height. COVIR is being developed as part of the NASA Instrument Incubator Program (IIP) as an engineering model. The goal of the lip is to develop laboratory prototype instruments that can be rapidly upgraded to meet flight standa rds and integrated into a spacecraft. The target spacecraft for the COVIR instrument is a sun synchronous, polar orbiting earth satellite at a nominal altitude of 600 km. This paper provides a description of the COVIR instrument, its operation, and performance."
"57200779707;6602598870;57206503586;","Simulation of a midlatitude convective storm initialized with bistatic Doppler radar data",2001,"10.1175/1520-0493(2001)129<1949:SOAMCS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035419144&doi=10.1175%2f1520-0493%282001%29129%3c1949%3aSOAMCS%3e2.0.CO%3b2&partnerID=40&md5=685c9f9da32f3a0a902522c6a73b4168","An analysis is developed to initialize a cloud-resolving model from an explicit structure of a precipitating convective system derived from multiple-Doppler radar observations. The different fields of the model prognostic variables that compose the initial state of the simulation are estimated or retrieved using a 4DVAR assimilation method in which the model is used as a weak constraint using two time level observations. This allows for the retrieval of physical fields consistent with the observations and the equations of the model. This method is applied on a midlatitude summer storm sampled by the McGill bistatic Doppler radar network that occurred on 2 August 1997. During the 30-min-forward simulation, the model succeeds in representing the observed features of the three main cells that compose the storm in terms of precipitation distribution and evolution of the convective activity. After this period, the model produces less stratiform precipitations. Comparisons with a Lagrangian persistency prediction are performed and show a notable improvement in the short-term forecast."
"57190531316;6506679005;7005117153;6505911830;","A regional model study of synoptic features over West Africa",2001,"10.1175/1520-0493(2001)129<1564:ARMSOS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035359678&doi=10.1175%2f1520-0493%282001%29129%3c1564%3aARMSOS%3e2.0.CO%3b2&partnerID=40&md5=0fe9ff3817fff444ea683195981f6da8","Synoptic weather features over West Africa were studied in simulations by the regional simulation model (RM) at the NASA Goddard Institute for Space Studies. These pioneering simulations represent the beginning of an effort to adapt regional models for weather and climate prediction over West Africa. The RM uses a Cartesian grid with 50-km horizontal resolution and 15 vertical levels. An ensemble of four simulations was forced with lateral boundary conditions from ECMWF global analyses for the period 8-22 August 1988. The simulated midtropospheric circulation includes the skillful development and movement of several African wave disturbances. Wavelet analysis of midtropospheric winds detected a dominant periodicity of about 4 days and a secondary periodicity of 5-8 days. Spatial distributions of RM precipitation and precipitation time series were validated against daily rain gauge measurements and International Satellite Cloud Climatology Project satellite infrared cloud imagery. The time-space distribution of simulated precipitation was made more realistic by combining the ECMWF initial conditions with a 24-h spinup of the moisture field and also by damping high-frequency gravity waves by dynamic initialization. Model precipitation ""forecasts"" over the central Sahel were correlated with observations for about 3 days, but reinitializing with observed data on day 5 resulted in a dramatic improvement in the precipitation validation over the remaining 9 days. Results imply that information via the lateral boundary conditions is not always sufficient to minimize departures between simulated and actual precipitation patterns for more than several days. In addition, there was some evidence that the new initialization may increase the simulations' sensitivity to the quality of lateral boundary conditions."
"6701404949;7003372165;36925376400;7101999921;7006783796;","CIMAR-5: A snapshot of the lower troposphere over the subtropical Southeast Pacific",2001,"10.1175/1520-0477(2001)082<2193:CASOTL>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001663862&doi=10.1175%2f1520-0477%282001%29082%3c2193%3aCASOTL%3e2.3.CO%3b2&partnerID=40&md5=b01a6d6e93649db66040aa04e44a81c2","The extensive and persistent deck of stratocumulus (SCu) off the west coast of subtropical South America plays an important role in the regional and global climate, as well as in coastal weather. As in other subtropical regions, the SCu form at the top of a marine boundary layer (MBL) bounded by a relatively cold ocean and a large-scale subsidence inversion. Nevertheless, details of the structure and variability of the lower troposphere over this region are largely unknown. Ship-based meteorological observations taken along a transect at 27°S from the Chilean coast (71°W) to Easter Island (110°W) during the second half of October 1999 provide a preliminary description of the low-level circulation, thermodynamic structure, and cloudiness over the subtropical southeast Pacific. Three types of observations were made: (a) 15-min average of air temperature, relative humidity, solar radiation, pressure, and wind by an automatic weather station on the ship deck; (b) 15-min average of vertical reflectivity and cloud base by a laser ceilometer on the ship deck; and (c) twice-daily rawinsondes. Several cloud and radiation properties were derived from GOES-8 imagery and validated against the ship-based observations. A preliminary assessment of the ability of NCEP-NCAR reanalysis and scatterometer winds in representing the atmosphere over a largely in situ data-void area is also presented. Sea surface temperature and near-surface air temperature increase gradually westward, while near-surface relative humidity remains nearly constant at ∼80%. A significant increase in the free-tropospheric moisture indicates an offshore decrease in the large-scale subsidence. Consistently, the MBL evolves from a shallow, well-mixed MBL topped by compact SCu near the coast; to a deeper, decoupled MBL with a cumuli rising into a patchy SCu deck rear Easter Island, in a similar fashion to the transition from subtropical-stratus regime to trade-cumulus regime described elsewhere. In addition to these ""climatological"" features, the ship data also reveal the large sensitivity of the MBL-trade inversion structure to synoptic-scale disturbances over the subtropical Pacific. Cloud droplet effective sizes increase from the coast to open ocean. Furthermore, cloud fraction, cloud-top height, liquid water path, and optical depth all peaked during the morning and reached a minimum by midafternoon."
"7006957668;7409376438;7402942478;57211301037;7004114883;35467186900;","Improving global analysis and short-range forecast using rainfall and moisture observations derived from TRMM and SSM/I passive microwave sensors",2001,"10.1175/1520-0477(2001)082<0659:IGAASF>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001733514&doi=10.1175%2f1520-0477%282001%29082%3c0659%3aIGAASF%3e2.3.CO%3b2&partnerID=40&md5=87408e90c2bc0aa743ea3ab95b940ed9","As a follow-on to the Tropical Rainfall Measuring Mission (TRMM), the National Aeronautics and Space Administration in the United States, the National Space Development Agency of Japan, and the European Space Agency are considering a satellite mission to measure the global rainfall. The plan envisions an improved TRMM-like satellite and a constellation of eight satellites carrying passive microwave radiometers to provide global rainfall measurements at 3-h intervals. The success of this concept relies on the merits of rainfall estimates derived from passive microwave radiometers. This article offers a proof-of-concept demonstration of the benefits of using rainfall and total precipitable water (TPW) information derived from such instruments in global data assimilation with observations from the TRMM Microwave Imager (TMI) and two Special Sensor Microwave/Imager (SSM/I) instruments. Global analyses that optimally combine observations from diverse sources with physical models of atmospheric and land processes can provide a comprehensive description of the climate systems. Currently, such data analyses contain significant errors in primary hydrological fields such as precipitation and evaporation, especially in the Tropics. It is shown that assimilating the 6-h-averaged TMI and SSM/I surface rain rate and TPW retrievals improves not only the hydrological cycle but also key climate parameters such as clouds, radiation, and the upper-tropospheric moisture in the analysis produced by the Goddard Earth Observing System Data Assimilation System, as verified against radiation measurements by the Clouds and the Earth's Radiant Energy System instrument and brightness temperature observations by the Television Infrared Observational Satellite Operational Vertical Sounder instruments. Typically, rainfall assimilation improves clouds and radiation in areas of active convection, as well as the latent heating and large-scale motions in the Tropics, while TPW assimilation leads to reduced moisture biases and improved radiative fluxes in clear-sky regions. Ensemble forecasts initialized with analyses that incorporate TMI and SSM/1 rainfall and TPW data also yield better short-range predictions of geopotential heights, winds, and precipitation in the Tropics. These results were obtained using a variational procedure based on a 6-h time integration of a column model of moist physics with prescribed dynamical and other physical tendencies. The procedure estimates moisture tendency corrections at observation locations by minimizing the least square differences between the observed TPW and rain rates and those generated by the column model over a 6-h analysis window. These tendency corrections are then applied during the assimilation cycle to compensate for errors arising from both initial conditions and deficiencies in model physics. Our results point to the importance of addressing deficiencies in model physics in assimilating data types such as precipitation, for which the forward model based on convective parameterizations may have significant systematic errors. This study offers a compelling illustration of the potential of using rainfall and TPW information derived from passive microwave instruments to significantly improve the quality of four-dimensional global datasets for climate analysis and weather forecasting applications."
"9636904200;7003314664;","The diurnal cycle in the tropics",2001,"10.1175/1520-0493(2001)129<0784:TDCITT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035302480&doi=10.1175%2f1520-0493%282001%29129%3c0784%3aTDCITT%3e2.0.CO%3b2&partnerID=40&md5=6ac35d189696d7b0fd940115abb10cdf","A global archive of high-resolution (3-hourly, 0.5° latitude-longitude grid) window (11-12 μm) brightness temperature (Tb) data from multiple satellites is being developed by the European Union Cloud Archive User Service (CLAUS) project. It has been used to construct a climatology of the diurnal cycle in convection, cloudiness, and surface temperature for all regions of the Tropics. An example of the application of the climatology to the evaluation of the climate version of the U.K. Met. Office Unified Model (UM), version HadAM3, is presented. The characteristics of the diurnal cycle described by the CLAUS data agree with previous observational studies, demonstrating the universality of the characteristics of the diurnal cycle for land versus ocean, clear sky versus convective regimes. It is shown that oceanic deep convection tends to reach its maximum in the early morning. Continental convection generally peaks in the evening, although there are interesting regional variations, indicative of the effects of complex land-sea and mountain-valley breezes, as well as the life cycle of mesoscale convective systems. A striking result from the analysis of the CLAUS data has been the extent to which the strong diurnal signal over land is spread out over the adjacent oceans, probably through gravity waves of varying depths. These coherent signals can be seen for several hundred kilometers and in some instances, such as over the Bay of Bengal, can lead to substantial diurnal variations in convection and precipitation. The example of the use of the CLAUS data in the evaluation of the Met. Office UM has demonstrated that the model has considerable difficulty in capturing the observed phase of the diurnal cycle in convection, which suggests some fundamental difficulties in the model's physical parameterizations. Analysis of the diurnal cycle represents a powerful tool for identifying and correcting model deficiencies."
"7005129538;36987542300;57194154633;","Sulphate aerosol size distributions at Mumbai, India, during the INDOEX-FFP (1998)",2001,"10.1016/S1352-2310(00)00440-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034743568&doi=10.1016%2fS1352-2310%2800%2900440-4&partnerID=40&md5=7e795022a40a853caca0e9825d614cec","Sulphate size distributions were measured at the coastal station of Mumbai (formerly Bombay) through 1998, during the Indian ocean experiment (INDOEX) first field phase (FFP), to fill current gaps in size-resolved aerosol chemical composition data. The paper examines meteorological, seasonal and source-contribution effects on sulphate aerosol and discusses potential effects of sulphate on regional climate. Sulphate size-distributions were largely trimodal with a condensation mode (mass median aerodynamic diameter or MMAD 0.6μm), a droplet mode (MMAD 1.9-2.4μm) and a coarse mode (MMAD 5μm). Condensation mode sulphate mass-fractions were highest in winter, consistent with the high meteorological potential for gas-to-particle conversion along with low relative humidity (RH). The droplet mode concentrations and MMADs were larger in the pre-monsoon and winter than in monsoon, implying sulphate predominance in larger sized particles within this mode. In these seasons the high RH, and consequently greater aerosol water in the droplet mode, would favour aerosol-phase partitioning and reactions of SO2. Coarse mode sulphate concentrations were lowest in the monsoon, when continental contribution to sulphate was low and washout was efficient. In winter and pre-monsoon, coarse mode sulphate concentrations were somewhat higher, likely from SO2 gas-to-particle conversion. Low daytime sulphate concentrations with a large coarse fraction, along with largely onshore winds, indicated marine aerosol predominance. High nighttime sulphate concentrations and a coincident large fine fraction indicated contributions from anthropogenic/industrial sources or from gas-to-particle conversion. Monthly mean sulphate concentrations increased with increasing SO2 concentrations, RH and easterly wind direction, indicating the importance of gas-to-particle conversion and industrial sources located to the east. Atmospheric chemistry effects on sulphate size distributions in Mumbai, indicated by this data, must be further examined. © 2001 Elsevier Science Ltd."
"7005056279;","The numerical representation of entrainment in parameterizations of boundary layer turbulent mixing",2001,"10.1175/1520-0493(2001)129<1148:TNROEI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035334972&doi=10.1175%2f1520-0493%282001%29129%3c1148%3aTNROEI%3e2.0.CO%3b2&partnerID=40&md5=67f1a94aeeb6132c68baf2a91ba02be5","Problems have been identified with parameterizations of convective boundary layers, in particular with their numerical treatment of the capping inversion. It is shown that the turbulence scheme can combine with the numerical representation of subsidence to produce unphysical entrainment, as was also identified by Lenderink and Holtslag. A correction is proposed for the Lock et al. boundary layer parameterization in which a discontinuous inversion is diagnosed from the mean thermodynamic profiles every time step. This then allows a consistent treatment of subgrid-scale processes in the region of the inversion. In particular, the parameterized turbulent entrainment flux can be adjusted to allow for the spurious entrainment arising from the conflicting representations of turbulent mixing and vertical advection. It also allows a direct coupling between the turbulent and radiative fluxes to ensure that cloud-top radiative cooling is correctly distributed between the inversion grid level and the mixed layer. The revised scheme demonstrates a much improved representation of stratocumulus-capped boundary layers, not only in single-column model tests but also in a climate-resolution GCM. In the latter, the semipermanent subtropical stratocumulus sheets appear realistic, both in terms of their cloud amount and their evolution. This suggests that a significant cause of the lack of stratocumulus in many GCMs may not be the inaccuracy of the parameterizations employed, but rather their numerical implementation."
"22982762300;7403309955;55915388400;26658279600;55581974700;7006597288;22958999700;24546705400;","Earthshine observations of the earth's reflectance",2001,"10.1029/2000GL012580","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035333062&doi=10.1029%2f2000GL012580&partnerID=40&md5=02325fa72724e0415b3fd3cef5deb0ef","Regular photometric observations of the moon's ""ashen light"" (earthshine) from the Big Bear Solar Observatory (BBSO) since December 1998 have quantified the earth's optical reflectance. We find large (∼ 5%) daily variations in the reflectance due to large-scale weather changes on the other side of the globe. Separately, we find comparable hourly variations during the course of many nights as the earth's rotation changes that portion of the earth in view. Our data imply an average terrestrial albedo of 0.297±0.005, which agrees with that from simulations based upon both changing snow and ice cover and satellite-derived cloud cover (0.296±0.002). However, we find seasonal variations roughly twice those of the simulation, with the earth being brightest in the spring. Our results suggest that long-term earthshine observations are a useful monitor of the earth's albedo. Comparison with more limited earthshine observations during 1994-1995 show a marginally higher albedo then."
"7006635125;57203809453;7202216319;","Dry and moist convection forced by an urban heat island",2001,"10.1175/1520-0450(2001)040<1462:DAMCFB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035416712&doi=10.1175%2f1520-0450%282001%29040%3c1462%3aDAMCFB%3e2.0.CO%3b2&partnerID=40&md5=8c3308e61ad6f27f1897fe07ffa744d0","This study numerically investigates dry and moist convection forced by an urban heat island using a two-dimensional, nonhydrostatic, compressible model with explicit cloud microphysical processes (Advanced Regional Prediction System). The urban heat island is represented by specified heating. Extensive numerical experiments with various heating amplitudes, representing the intensity of the urban heat island, uniform basic-state wind speeds, and basic-state relative humidities, are performed to examine their roles in characterizing urban-induced convection. Two flow regimes can be identified in dry simulations. One regime is characterized only by stationary gravity waves near the heating region and is revealed when the urban heat island intensity is very weak. The other regime is characterized both by stationary gravity waves near the heating region and by a downwind updraft cell that moves in the downstream direction. The intensity of the downwind updraft cell increases as the heat island intensity increases or the basic-state wind speed decreases. Results of moist simulations demonstrate that the downwind updraft cell induced by the urban heat island can initiate moist convection and result in surface precipitation in the downstream region when the basic-state thermodynamic conditions are favorable. As the urban heat island intensity increases, the time required for the first cloud water (or rainwater) formation decreases and its horizontal location is closer to the heating center. It is shown that for the same basic-state wind speed and heat island intensity a stronger dynamic forcing-that is, a stronger downwind updraft-is needed to trigger moist convection in less favorable basic-state thermodynamic conditions."
"7004159166;7003406860;7006084942;7004352797;6601983684;7102517130;7402504360;7006270084;7003931528;6603267159;57202917221;56249704400;7006074773;57203053317;7006705919;","Analysis of regional budgets of sulfur species modeled for the COSAM exercise",2001,"10.3402/tellusb.v53i5.16644","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035150088&doi=10.3402%2ftellusb.v53i5.16644&partnerID=40&md5=53391b38a240600ea9ceb6cbe51e09d3","The COSAM intercomparison exercise (comparison of large-scale sulfur models) was organized to compare and evaluate the performance of global sulfur cycle models. Eleven models participated, and from these models the simulated surface concentrations, vertical profiles and budget terms were submitted. This study focuses on simulated budget terms for the source and sinks of SO2 and sulfate in three polluted regions in the Northern Hemisphere, i.e., eastern North America. Europe, and Southeast Asia. Qualitatively, features of the sulfur cycle are modeled quite consistently between models, such as the relative importance of dry deposition as a removal mechanism for SO2, the importance of aqueous phase oxidation over gas phase oxidation for SO2, and the importance of wet over dry deposition for removal of sulfate aerosol. Quantitatively, however, models may show large differences, especially for cloud-related processes, i.e., aqueous phase oxidation of SO2 and sulfate wet deposition. In some cases a specific behavior can be related to the treatment of oxidants for aqueous phase SO2 oxidation, or the vertical resolution applied in models. Generally, however, the differences between models appear to be related to simulated cloud (micro-)physics and distributions, whereas differences in vertical transport efficiencies related to convection play an additional rôle. The estimated sulfur column burdens, lifetimes and export budgets vary between models by about a factor of 2 or 3. It can be expected that uncertainties in related effects which are derived from global sulfur model calculations, such as direct and indirect climate forcing estimates by sulfate aerosol, are at least of similar magnitude."
"35571076700;","Assessment of the quality of thunderstorm data at first-order stations",2001,"10.1175/1520-0450(2001)040<0783:AOTQOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035304555&doi=10.1175%2f1520-0450%282001%29040%3c0783%3aAOTQOT%3e2.0.CO%3b2&partnerID=40&md5=e13b2f1994dd0a07f6e7ba31c26f6539","Climatological assessments of past fluctuations in thunderstorms and other weather extremes require high-quality records. Data on thunder-day occurrences exist at U.S. first-order stations (FOS) since 1894 and represent the only long-term data available for temporal thunderstorm assessments. A thunder day is based on hearing thunder, and hence audibility is a major factor affecting record quality. Assessment of the potential conditions that affect audibility and of other factors that influence record quality identified four factors. Changes in audibility can occur from structural changes at the station, altered levels of noise such as increased aircraft operations, and relocations of stations to sites with different audibility conditions. Another data-limiting factor is local changes in storm activity due to urban influences on the atmosphere. Station relocations in areas where sharp natural differences in storm frequency exist such as in coastal and mountainous sites are a third factor affecting local values, and uncertainties related to record keeping are the fourth. The quality of the thunder-day records at the 130 U.S. FOS with 90 or more years of data during 1896-1995 were evaluated using a five-step process. First, the historical thunder-day frequencies were compared with the station relocations to detect any major changes after site changes. Second were tests of homogeneity using data from surrounding stations. The third step involved comparison of each station's historical fluctuations with those of surrounding stations to identify anomalous values that persisted for 20 years or more. Step four involved assessment of possible urban effects on local storm frequencies using past findings and assessments of where and when urban storm activity may have changed in relation to the locations of the local weather station. Fifth, reported thunderstorms were compared with nearby cloud-to-ground lightning strokes to assess unreported thunder occurrences. Homogeneity testing revealed that 10 FOS had questionable records resulting from major multidecadal shifts in values, often a result of station relocations. Six other stations had urban influences on local storm activity that made their records unrepresentative of regional climate conditions, and four stations had anomalously low values of storms based on comparisons with nearby lightning activity. In all, 20 of the 130 stations with long records were found to have records unsuitable for long-term climatic assessments."
"7202063177;6602496205;55574192743;56236961900;57214439262;","Measurements of water vapour in the mesosphere with the Spectral Absorption Line Imager (SALI)",2001,"10.1016/S0273-1177(01)00142-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034813501&doi=10.1016%2fS0273-1177%2801%2900142-9&partnerID=40&md5=d3b005e500c19094ebfd93060c9a84f8","Water vapour concentration is one of the most important, yet one of the least known quantities of the mesosphere. Knowledge of water vapour concentration is the key to understanding many mesospheric processes, including the one that is primary focus of our investigation, Polar Mesospheric Clouds (PMC). The processes of formation and occurrence parameters of PMC constitute an interesting problem in their own right, but recent evidence had been provided which suggests that PMC are a critical indicator of climate change. In this context the feasibility of a low cost method of water vapour measurements using an instrument carried aloft by a sounding rocket has been examined and some of the results discussed. It is proposed to measure the strength of the 936nm water absorption line in a solar occultation configuration employing a CCD detector. This leads to the design of a small, low cost and low-mass instrument, which can be flown on a small rocket, of the type of the Orbital Sciences Corporation Viper 5. Alternatively the instrument can be flown as a ""passenger"" on larger rocket carrying other experiments. In either case flight costs are relatively low. Some performance simulations are presented showing that the instrument we have designed will be sufficiently sensitive to measure water vapor in concentrations that are expected at the summer mesopause, about 85 km height. Sufficient payload design work was carried out showing that the structural, thermal and electrical requirements for a flight on the Viper 5 rocket can be met and thus making the experiment feasible for a flight. © 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved."
"6701594089;7003377229;","Blue-ice areas in Antarctica derived from NOAA AVHRR satellite data",2001,"10.3189/172756501781832386","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035194956&doi=10.3189%2f172756501781832386&partnerID=40&md5=9caf905e2094007bedf716278da29c82","We have mapped Antarctic blue-ice areas using the U.S. National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) Antarctica cloud-free image mosaic established by the United States Geological Survey. The mosaic consists of 38 scenes acquired from 1980 to 1994. Our results show that approximately 60 000 km2 of blue ice exist for each of the two main types of blue ice: ""melt-induced"" and ""wind-induced"". Normally, the former type is located on slopes in coastal areas where climate conditions (i.e. persistent winds and temperature), together with favourable surface orientation, sustain conditions for surface and near-surface melt. The latter blue-ice category occurs near mountains or on outlet glaciers, often at higher elevations, where persistent winds erode snow away year-round, and combined with sublimation creates areas of net ablation. Furthermore, we have identified an additional area of 121 000 km2 as having potential for blue ice. However, in these areas features such as mixed pixels, glazed snow surfaces, crevasses and/or shadows make interpretation more uncertain. In conclusion, a conservative estimate of Antarctic blue-ice area coverage by this method is found to be 120 000 km2 (~0%.8% of the Antarctic continent), with a potential maximum of 241 000 km2 (~1.6% of the Antarctic continent)."
"55393008200;7006861689;56909353000;","Forest vegetation characterization and mapping using IRS-1C satellite images in Eastern Himalayan Region",2001,"10.1080/10106040108542204","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042771140&doi=10.1080%2f10106040108542204&partnerID=40&md5=c67b1bc2083bf2fba791f5e138312a99","IRS 1C LISS-III sensor data was used to generate a medium scale vegetation cover map. Four scenes with minimum cloud cover were acquired, pre-processed and geo-referenced to Survey of India (SOI) topomaps. The satellite images were then subjected to knowledge-based hybrid classification. A standard forest vegetation / land cover classification legend was used for this purpose. All the vegetation classes were visited on ground to collect information on their structure and composition, which was utilized in the classification exercise. Total land cover of over 20000 km2 of Subansiri Himalaya was classified into seventeen categories. The vegetation classes derived from digital classification were compared with the existing ground-based forest classification given by Champion and Seth. Area estimates were made for various land cover categories. Distribution of various forest vegetation types when compared with altitudinal zones of the area has shown good relationship. Correspondence using field-gathered GPS points for vegetation classes showed 89.25% overall accuracy. The methodology used here for classification exercise has contributed to improved classification accuracy. All the vegetation classes have been described with respect to their dominant species composition, spectral response on satellite images, occurrence zone with respect to altitude &amp; climate and their correspondence with existing ground-based forest type classification given by Champion and Seth. This study envisages the use of satellite remote sensing and its kindred technologies like GIS and GPS supplemented by ground-based limited field survey for characterizing forest vegetation cover."
"55113736500;","Global direct radiative forcing due to multicomponent anthropogenic and natural aerosols",2001,"10.1029/2000jd900514","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035053073&doi=10.1029%2f2000jd900514&partnerID=40&md5=f5bf0fa68319860f899e0b454e2ddba7","Global simulations of the composition of and direct forcing due to aerosols containing natural and/or anthropogenic sulfate, nitrate, chloride, carbonate, ammonium, sodium, calcium, magnesium, potassium, black carbon, organic matter, silica, ferrous oxide, and aluminum oxide were carried out. Chloride and natural sulfate were found to be the most important natural aerosol constituents in the atmosphere in terms of solar plus thermal-infrared forcing. Sea spray was the most important natural aerosol type, indicating that it should be accounted for in weather and climate calculations. Ammonium was found to have a positive direct forcing, since it reduces water uptake in sulfate-containing solutions; thus, anthropogenic ammonium contributes to global warming. The magnitudes of ammonium and nitrate forcing were smaller than those of chloride or sulfate forcing. When organics were divided into three groups with different assumed UV absorption characteristics, total aerosol direct forcing at the tropopause increased by about +0.03 to +0.05 W m-2 (direct forcing by organics remained negative), suggesting that UV absorption by organics is a nontrivial component of the global energy balance. Gypsum [CaSO4-2H2O], sal ammoniac [NH4Cl], halite [NaCl], halite, and nitrum [KNO3] were estimated to be the most common sulfate-, ammonium-, sodium-, chloride-, and nitrate-containing solid-phase aerosol constituents, respectively, in the global atmosphere. Solid formation in aerosols was found to increase total-aerosol direct forcing by +0.03 to +0.05 W m-2. Spatial and vertical forcing estimates, sensitivities of forcing to relative humidity and concentration, and estimates of global aerosol liquid water content are given. Modeled aerosol optical properties are compared with satellite and field measurements."
"6602164207;","Lapse rate changes in northern England",2001,"10.1007/s007040170049","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035094067&doi=10.1007%2fs007040170049&partnerID=40&md5=6f80daad4483f3ef3127d24d94f794a6","Most GCMs indicate distinct elevational signals in temperature response to global warming, both in the free-air and at the surface, although modelled changes are spatially variable, in magnitude and in sign. In this study, daily climate observations (1968-1995) from two sites in northern England, representative of upland and lowland environments, are used to derive a regionally representative lapse rate. The lapse rates of daily maximum and minimum temperatures show strong seasonal and diurnal patterns, and relationships with synoptic conditions, classified using the Lamb classification. Synoptic types with westerly components show the most rapid decrease of temperature with elevation. Lapse rates are also steeper when there is a strong altitudinal increase in cloud cover, decrease in sunshine duration, or strong wind shear. Lapse rates are becoming steeper by day but weaker at night (p < 0.1%). Such changes occur within most synoptic types, and there are not many statistically significant changes in relative airflow frequencies. Weak relationships exist between measurements of the NAO and lapse rates, but within airflow-type modification is also influential, being connected with changes in SSTs to the west of the U.K. Correlations between mean monthly lapse rates and SSTs vary spatially. Low SSTs in the north and high SSTs in the south of the region encourage steep daytime lapse rates, implying a steeper lapse rate under a stronger meridional temperature gradient. At night the opposite relationship holds. Over time there has been strengthening in the meridional SST gradient to the west of the U.K., confirmed by analysis of a SST data set from CRU (1968-1995). This correlates with the increased diurnal lapse rate signal. Changes in upland temperatures in northern England are dependent on variable lapse rate modification for individual synoptic types, in this case influenced by upwind SSTs and their meridional gradient. Thus different mountain ranges will react in contrasting ways to global warming."
"36724322000;7006186794;6603130624;7003937114;6602113713;7103311365;6603244946;6602863880;7202642044;7403068412;7003958615;7402390888;6506354630;57213941483;7003507545;57197077309;6602570835;","BOBMEX: The Bay of Bengal Monsoon experiment",2001,"10.1175/1520-0477(2001)082<2217:BTBOBM>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000339443&doi=10.1175%2f1520-0477%282001%29082%3c2217%3aBTBOBM%3e2.3.CO%3b2&partnerID=40&md5=09310fc75ceae64e3399edbf36f61181","The first observational experiment under the Indian Climate Research Programme, called the Bay of Bengal Monsoon Experiment (BOBMEX), was carried out during July-August 1999. BOBMEX was aimed at measurements of important variables of the atmosphere, ocean, and their interface to gain deeper insight into some of the processes that govern the variability of organized convection over the bay. Simultaneous time series observations were carried out in the northern and southern Bay of Bengal from ships and moored buoys. About 80 scientists from 15 different institutions in India collaborated during BOBMEX to make observations in most-hostile conditions of the raging monsoon. In this paper, the objectives and the design of BOBMEX are described and some initial results presented. During the BOBMEX field phase there were several active spells of convection over the bay, separated by weak spells. Observation with high-resolution radiosondes, launched for the first time over the northern bay, showed that the magnitudes of the convective available potential energy (CAPE) and the convective inhibition energy were comparable to those for the atmosphere over the west Pacific warm pool. CAPE decreased by 2-3 kJ kg-1 following convection, and recovered in a time period of 1-2 days. The surface wind speed was generally higher than 8 m s-1. The thermohaline structure as well as its time evolution during the BOBMEX field phase were found to be different in the northern bay than in the southern bay. Over both the regions, the SST decreased during rain events and increased in cloud-free conditions. Over the season as a whole, the upper-layer salinity decreased for the north bay and increased for the south bay. The variation in SST during 1999 was found to be of smaller amplitude than in 1998. Further analysis of the surface fluxes and currents is expected to give insight into the nature of coupling."
"7005578774;35984036000;6603141288;","The atmospheric energy budget and implications for surface fluxes and ocean heat transports",2001,"10.1007/PL00007927","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034842322&doi=10.1007%2fPL00007927&partnerID=40&md5=edd6bc7f4b1d600d47d174cfbf91916f","Comprehensive diagnostic comparisons and evaluations have been carried out with the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) and European Centre for Medium Range Weather Forecasts (ECMWF) reanalyses of the vertically integrated atmospheric energy budgets. For 1979 to 1993 the focus is on the monthly means of the divergence of the atmospheric energy transports. For February 1985 to April 1989, when there are reliable top-of-the-atmosphere (TOA) radiation data from the Earth Radiation Budget Experiment (ERBE), the implied monthly mean surface fluxes are derived and compared with those from the assimilating models and from the Comprehensive Ocean Atmosphere Data Set (COADS), both locally and zonally integrated, to deduce the implied ocean meridional heat transports. While broadscale aspects and some details of both the divergence of atmospheric energy and the surface flux climatological means are reproducible, especially in the zonal means, differences are also readily apparent. Systematic differences are typically ~20 W m-2. The evaluation highlights the poor results over land. Land imbalances indicate local errors in the divergence of the atmospheric energy transports for monthly means on scales of 500 km (T31) of 30 W m-2 in both reanalyses and ~50 W m-2 in areas of high topography and over Antarctica for NCEP/NCAR. Over the oceans in the extratropics, the monthly mean anomaly time series of the vertically integrated total energy divergence from the two reanalyses correspond reasonably well, with correlations exceeding 0.7. A common monthly mean climate signal of about 40 Wm-2 is inferred along with local errors of 25 to 30 W m-2 in most extratropical regions. Except for large scales, there is no useful common signal in the tropics, and reproducibility is especially poor in regions of active convection and where stratocumulus prevails. Although time series of monthly anomalies of surface bulk fluxes from the two models and COADS agree very well over the northern extratropical oceans, the total fields all contain large systematic biases which make them unsuitable for determining ocean heat transports. TOA biases in absorbed shortwave, outgoing longwave and net radiation from both reanalysis models are substantial (&gt;20 W m-2 in the tropics) and indicate that clouds are a primary source of problems in the model fluxes, both at the surface and the TOA. Time series of monthly COADS surface fluxes are shown to be unreliable south of about 20°N where there are fewer than 25 observations per 5° square per month. Only the derived surface fluxes give reasonable implied meridional ocean heat transports."
"7004533232;7101912085;7005449794;","Simulation of regional-scale water and energy budgets: Representation of subgrid cloud and precipitation processes within RegCM",2000,"10.1029/2000JD900415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034452195&doi=10.1029%2f2000JD900415&partnerID=40&md5=e0bf8ff7a6b550ed7274898a20302ed0","A new large-scale cloud and precipitation scheme, which accounts for the subgrid-scale variability of clouds, is coupled to NCAR's Regional Climate Model (RegCM). This scheme partitions each grid cell into a cloudy and noncloudy fraction related to the average grid cell relative humidity. Precipitation occurs, according to a specified autoconversion rate, when a cloud water threshold is exceeded. The specification of this threshold is based on empirical in-cloud observations of cloud liquid water amounts. Included in the scheme are simple formulations for raindrop accretion and evaporation. The results from RegCM using the new scheme, tested over North America, show significant improvements when compared to the old version. The outgoing longwave radiation, albedo, cloud water path, incident surface shortwave radiation, net surface radiation, and surface temperature fields display reasonable agreement with the observations from satellite and surface station data. Furthermore, the new model is able to better represent extreme precipitation events such as the Midwest flooding observed in the summer of 1993. Overall, RegCM with the new scheme provides for a more accurate representation of atmospheric and surface energy and water balances, including both the mean conditions and the variability at daily to interannual scales. The latter suggests that the new scheme improves the model's sensitivity, which is critical for both climate change and process studies. Copyright 2000 by the American Geophysical Union."
"7004713805;6603014245;57192912623;15758193700;16439174800;","Nonhydrostatic climate simulations of precipitation over complex terrain",2000,"10.1029/2000JD900445","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034451323&doi=10.1029%2f2000JD900445&partnerID=40&md5=a60e0993f80fbc9af7a63a094c1cc8b8","A climate version of the nonhydrostatic fifth-generation Penn State/NCAR Mesoscale Model has been used to downscale a global climate scenario to cloud-resolving scales over complex terrain (the Alps). After first describing the model and methodology, we then present comparison results from the model-predicted and ensemble-averaged regional-scale winter and summer season precipitation distribution with results from the global simulation and analyzed observed precipitation climatologies. Finally, results from the cloud-resolving simulations are compared to the regional simulations. It is shown that the degree to which the terrain is resolved in the various runs significantly alters the simulation of the precipitation climatologies. This is caused not only by the complex interaction of the flow with the topography but also by the different treatment of the convective processes (resolved versus nonresolved) in the model. Even in winter, the model-simulated seasonally averaged precipitation patterns change drastically with every increase in horizontal resolution. Furthermore, with a horizontal grid resolution of 1 km, when seen on a local scale and over complex terrain, the model-simulated precipitation patterns are not guaranteed to converge to one solution. This behavior is still more complicated in summer. Here it is shown that parameterized convection in the regional model simulation tends to be locked to the mountains, while in the cloud-resolving simulations the convection moves with the upper level flow, producing precipitation maxima away from the mountain tops. Copyright 2000 by the American Geophysical Union."
"7405367162;7005070958;","Validation of longwave atmospheric radiation models using Atmospheric Radiation Measurement data",2000,"10.1029/2000JD900557","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034450371&doi=10.1029%2f2000JD900557&partnerID=40&md5=d2efa96bab2ad885a090d5619978aa42","Data taken at the Atmospheric Radiation Measurement Program's central facility in Oklahoma and processed as part of the Clouds and the Earth's Radiant Energy System-Atmospheric Radiation Measurement-Global Energy and Water Cycle Experiment (CAGEX) project have been used to validate the top-of-the-atmosphere and surface longwave radiative fluxes for two widely used radiation models: the Column Radiation Model from the National Center for Atmospheric Research Community Climate Model (CCM), and the Moderate Resolution Transmittance (MODTRAN3) radiation code. The results show that for clear skies the models slightly overestimate outgoing longwave radiation at the top of the atmosphere (OLR) and underestimate the surface downwelling longwave flux (SDLW). The accuracy of the radiation models is quite consistent with their respective levels of complexity. For MODTRAN3, for example, the OLR overestimate is 7.1 Wm-2 while the SDLW underestimate is 4.2 Wm-2. For cloudy skies it is emphasized that the cloud input parameters, as determined from measurements by various instruments, require careful examination and preprocessing. Spatial and temporal averaging could result in the parameters representing different volumes of the atmosphere. The discrepancy between model calculations and observations is shown to be significantly reduced through the proper choice of input parameters. Copyright 2000 by the American Geophysical Union."
"6701324864;7202162685;","A new theory of heterogeneous ice nucleation for application in cloud and climate models",2000,"10.1029/1999GL011211","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034670986&doi=10.1029%2f1999GL011211&partnerID=40&md5=2538e05529c40a14f6985a5fd5435ab2","A new formulation is presented of the thermodynamical theory of heterogeneous ice crystal nucleation in clouds by freezing. This theory unifies and explains the empirical ice nuclei dependence on temperature and supersaturation, predicts crystal formation via condensation-freezing at a subsaturation over water. The theory also explains observations of high nucleation rates and crystal concentrations at warm (-5 > -12 °C) temperatures when the splintering mechanism may be not effective. This theory can be applied to parameterizations for use in cloud and climate models."
"7401984344;7004442182;57203215073;6602184922;","Temporal changes in the observed relationship between cloud cover and surface air temperature",2000,"10.1175/1520-0442(2000)013<4341:TCITOR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034670350&doi=10.1175%2f1520-0442%282000%29013%3c4341%3aTCITOR%3e2.0.CO%3b2&partnerID=40&md5=bb1d9341c9e4ac276d8c25771fb1099f","The relationship between cloud cover and near-surface air temperature and its decadal changes are examined using the hourly synoptic data for the past four to six decades from five regions of the Northern Hemisphere: Canada, the United States, the former Soviet Union, China, and tropical islands of the western Pacific. The authors define the normalized cloud cover-surface air temperature relationship, NOCET or dT/dCL, as a temperature anomaly with a unit (one-tenth) deviation of total cloud cover from its average value. Then mean monthly NOCET time series (night- and daytime, separately) are area-averaged and parameterized as functions of surface air humidity and snow cover. The day- and nighttime NOCET variations are strongly anticorrelated with changes in surface humidity. Furthermore, the daytime NOCET changes are positively correlated to changes in snow cover extent. The regionally averaged nighttime NOCET varies from -0.05 K tenth-1in the wet Tropics to 1.0 K tenth-1at midlatitudes in winter. The daytime regional NOCET ranges from -0.4 K tenth-1in the Tropics to 0.7 K tenth-1 at midlatitudes in winter. The authors found a general strengthening of a daytime surface cooling during the post-World War II period associated with cloud cover over the United States and China, but a minor reduction of this cooling in higher latitudes. Furthermore, since the 1970s, a prominent increase in atmospheric humidity has significantly weakened the effectiveness of the surface warming (best seen at nighttime) associated with cloud cover. The authors apportion the spatiotemporal field of interactions between total cloud cover and surface air temperature into a bivariate relationship (described by two equations, one for daytime and one for nighttime) with surface air humidity and snow cover and two constant factors. These factors are invariant in space and time domains. It is speculated that they may represent empirical estimates of the overall cloud cover effect on the surface air temperature."
"7403531523;7404150761;6602137606;7801645594;","Validation of the CERES/TRMM ERBE-like monthly mean clear-sky longwave dataset and the effects of the 1998 ENSO event",2000,"10.1175/1520-0442(2000)013<4256:VOTCTE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034670338&doi=10.1175%2f1520-0442%282000%29013%3c4256%3aVOTCTE%3e2.0.CO%3b2&partnerID=40&md5=1b8ec81b9350f7e516f75143006d04ca","The Clouds and the Earth's Radiant Energy System (CERES) is a new National Aeronautics and Space Administration space-borne measurement project for monitoring the radiation environment of the earth-atmosphere system. The first CERES instrument was launched into space on board the Tropical Rainfall Measuring Mission (TRMM) satellite on 27 November 1997. The purpose of this paper is 1) to describe the initial validation of the new CERES/TRMM Earth Radiation Budget Experiment (ERBE)-like monthly mean clear-sky longwave (CLW) dataset and 2) to demonstrate the scientific benefit of this new dataset through a data application study on the 1998 El Nino-Southern Oscillation (ENSO) episode. The initial validation of the CERES CLW data is carried out based on comparisons with both historical ERBE observations and radiative transfer simulations. While the observed CERES CLWs are initially larger than the historical ERBE record during the first part of the 1998 ENSO event, these differences are diminished by the end of the ENSO event in July 1998. These unique ENSO-related CLW radiation signatures are captured well by the radiative transfer model simulations. These results demonstrate that the new CERES CLW fluxes are theoretically consistent with the underlying physics of the atmosphere. A CERES data application study is performed to examine the relationship between the CERES CLW anomaly and changes in sea surface temperature (SST) and atmospheric column precipitable water content (PWC) during the January 1998 ENSO event. While the changes in the SST pattern are basically uncorrelated with changes in the CLW field, a negative correlation is found between the PWC anomaly and the changes in the CLW radiation field. These observed features point to 1) the significant role of the water vapor field in modulating the tropical outgoing CLW radiation field during the 1998 ENSO event and 2) the important effects of water vapor absorption in decoupling the top of the atmosphere tropical outgoing CLW radiation from the surface upward CLW field."
"7102567936;7004479957;","Modeling tropical precipitation in a single column",2000,"10.1175/1520-0442(2000)013<4378:MTPIAS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034670348&doi=10.1175%2f1520-0442%282000%29013%3c4378%3aMTPIAS%3e2.0.CO%3b2&partnerID=40&md5=8ad0784324e7e83a1b68eced3b31a3e4","A modified formulation of the traditional single column model for representing a limited area near the equator is proposed. This formulation can also be considered a two-column model in the limit as the area represented by one of the columns becomes very large compared to the other. Only a single column is explicitly modeled, but its free tropospheric temperature, rather than its mean vertical velocity, is prescribed. This allows the precipitation and vertical velocity to be true prognostic variables, as in prior analytical theories of tropical precipitation. Two models developed by other authors are modified according to the proposed formulation. The first is the intermediate atmospheric model of J. D. Neelin and N. Zeng, but with the horizontal connections between columns broken, rendering it a set of disconnected column models. The second is the column model of N. O. Rennó, K. A. Emanuel, and P. H. Stone. In the first model, the set of disconnected column models is run with a fixed temperature that is uniform in the Tropics, and insolation, SST, and surface wind speed taken from a control run of the original model. The column models produce a climatological precipitation field that is grossly similar to that of the control run, despite that the circulation implied by the column models is not required to conserve mass. The addition of horizontal moisture advection by the wind from the control run substantially improves the simulation in dry regions. In the second model the sensitivity of the modeled steady-state precipitation and relative humidity to varying SST and wind speed is examined. The transition from shallow to deep convection is simulated in a ""Lagrangian"" calculation in which the column model is subjected to an SST that increases in time. In this simulation, the onset of deep convection is delayed to a higher SST than in the steady-state case, due to the effect of horizontal moisture advection (viewed in a Lagrangian reference frame). In both of the models, the steady-state moisture convergence is a nearly unique function of the surface evaporation when horizontal moisture advection is neglected, a result that is explained in terms of the moisture and moist static energy budgets. The proposed formulation can also be applied to limited-area three-dimensional models, such as cloud-resolving models. Additionally, with further development, it may be possible to use the fixed-temperature constraint as the basis for a truncated atmospheric dynamics appropriate for the study of tropical climate."
"7005350396;7103033590;","Impact of ENSO on the variability of the Asian-Australian Monsoons as simulated in GCM experiments",2000,"10.1175/1520-0442(2000)013<4287:IOEOTV>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034670342&doi=10.1175%2f1520-0442%282000%29013%3c4287%3aIOEOTV%3e2.0.CO%3b2&partnerID=40&md5=3d5ca0b92d11b7ff0aeacf911d982e16","The influences of El Nino-Southern Oscillation (ENSO) on the summer- and wintertime precipitation and circulation over the principal monsoon regions of Asia and Australia have been studied using a suite of 46-yr experiments with a 30-wavenumber, 14-level general circulation model. Observed monthly varying sea surface temperature (SST) anomalies for the 1950-95 period have been prescribed in the tropical Pacific in these experiments. The lower boundary conditions at maritime sites outside the tropical Pacific are either set to climatological values [in the Tropical Ocean Global Atmosphere (TOGA) runs], predicted using a simple 50-m oceanic mixed layer (TOGA-ML runs), or prescribed using observed monthly SST variations. Four independent integrations have been conducted for each of these three forcing scenarios. The essential characteristics of the model climatology for the Asian-Australian sector compare well with the observations. Composites of the simulated precipitation data over the outstanding warm and cold ENSO events reveal that a majority of the warm episodes are accompanied by below-normal summer rainfall in India and northern Australia, and above-normal winter rainfall in southeast Asia. The polarity of these anomalies is reversed in the cold events. These relationships are particularly evident in the TOGA experiment. Composite charts of the simulated flow patterns at 850 and 200 mb indicate that the above-mentioned precipitation changes are associated with well-defined circulation features over the affected monsoon regions. Dry conditions are typically coincident with low-level anticyclonic anomalies, and vice versa. These circulation centers are situated to the northwest and southwest of a prominent precipitation anomaly situated near 120°-150°E at the equator, which corresponds to the western half of a dipolar heating pattern resulting from eastwest displacements of the ascending branch of the Walker circulation during ENSO. The large-scale anomalous circulation over the monsoon regions is similar to that of a Rossby wave pattern associated with a condensational heat source or sink in the western equatorial Pacific. Diagnosis of the output from the TOGA-ML experiment reveals that variations in the circulation and cloud cover accompanying ENSO-induced monsoon anomalies could modulate the latent heat and shortwave radiative fluxes at the air-sea interface in the Indian Ocean, thereby changing the SST conditions in that basin. These simulated SST anomalies compare well with observational results. The local atmospheric response to these SST anomalies opposes the remote response of the south Asian monsoon flow to SST anomalies in the tropical Pacific, thus leading to a negative feedback loop in the air-sea coupled system."
"6603875926;6603906450;6603318870;7004828383;","Mid-holocene and Last Glacial Maximum African monsoon changes as simulated within the Paleoclimate Modelling Intercomparison Project",2000,"10.1016/S0921-8181(00)00033-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033724682&doi=10.1016%2fS0921-8181%2800%2900033-3&partnerID=40&md5=a4d30f38326cfdc9f190dd3bcc104f2a","As part of the Paleoclimate Modelling Intercomparison Project (PMIP), several atmospheric general circulation models have performed climate simulations of the mid-Holocene (6 ka BP) and of the Last Glacial Maximum (LGM) climates (21 ka BP) using the same experimental design for boundary conditions, insolation and CO2 forcing. PMIP results are used in this study to investigate how the position of the intertropical convergence zone (ITCZ) changes over West Africa throughout the seasonal cycle in these two climates. The Mid-Holocene corresponds to a period of enhanced seasonal cycle with colder winters and warmer summers, leading to an increase of the African monsoon. During LGM, the presence of large ice sheets and lower CO2 give rise to a colder climate and a reduced summer monsoon. For the two time periods and all the models, it is found that over West Africa, both the atmospheric low level temperature gradient and the position of the maximum of surface temperature control the position of the ITCZ. The energetic changes associated with the change in the hydrological cycle are driven by latent heat release in the atmosphere within the rainbelt and by radiative fluxes north of the ITCZ. The sensible heat flux plays also a non-negligible role over the desert during mid-Holocene. Differences between the PMIP simulations reflect differences in model parameterization, including surface processes and clouds. However, for a given model, the partitioning between the changes in the different heat fluxes is quite similar for the mid-Holocene and the LGM climate change. (C) 2000 Elsevier Science B.V."
"7003627420;","Last Glacial Maximum lacustrine and fluviatile formations in the Tibesti and other Saharan mountains, and large-scale climatic teleconnections linked to the activity of the Subtropical Jet Stream",2000,"10.1016/S0921-8181(00)00039-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033711704&doi=10.1016%2fS0921-8181%2800%2900039-4&partnerID=40&md5=3c836108a34f8233b15867cfdd18a737","In the mountains of the central Sahara (lat ca. 20°to 22°N, long 16°to 19°E) and particularly in the Tibesti mountains, important lacustrine formations developed during the late Pleistocene, primarily during the Last Glacial Maximum (LGM). Two main phases, separated by a brief regression, intervened between ca. 20,000 and 15,500 BP, and between 15,000 and 12,500 BP. Pollen analyses were carried out on four samples of this formation. The high lacustrine levels were associated to both important precipitations and a reduced evaporation linked to lower temperatures. Similar lacustrine deposits were found in the Djebel Marra in the south of the Sahara. In the mountains of the central and eastern Sahara, during the same period and until the middle Holocene, the 'Middle Terrace' Formation was deposited in the river valleys of the Tibesti, Hoggar, Air and the Red Sea Hills. Since the southern headwaters of the Nile were dry from ca. 20,000 to 12,500 BP, the fluviatile sediments deposited in the Nile valley in Nubia may have resulted almost entirely from the numerous wadis flowing from the Red Sea Hills. The rainfalls which fed these lacustrine and fluviatile formations were related to the Tropical Depressions which are formed in the southern part of the westerlies and are linked to the activity of the Subtropical Jet Stream (STJ), whose path remained over the central Sahara from 20,000 BP to the early Holocene. In the Rocky Mountains of the western US, the palaeolakes Lahontan and Bonneville were very large during the LGM and the main fluctuations exhibit similar chronology to that of the Saharan mountains. Broecker [Broecker, W.S., 1994. Massive iceberg discharges as triggers for global climate change. Nature 372, 421-424] estimates that these two large U.S. wet events between ca. 20,000-15,500 BP and ca. 15,000-12,500 BP may have been an indirect result of two large ice surges in the North Atlantic, related to Heinrich layers 1 and 2. We can assume, however, that the similar climatic variation of the Rocky Mountains and the central and eastern Saharan mountains was also a result of the activity of the STJ all along its path, which marks the boundary between the polar and tropical circulations. STJ activity can apparently produce long-distance climatic teleconnections. During the LGM similar teleconnections also existed in the Southern Hemisphere between South Africa and Australia. The Tropical Depressions result from the interaction of polar troughs and the influx of humid equatorial air forming transversal cloud bands. The large increase in the intensity of atmospheric circulation during the LGM was responsible for a large increase in Tropical Depressions in both hemispheres. (C) 2000 Elsevier Science B.V."
"7006573844;7006792445;24560382000;6701858523;","Dimethylsulfide production variations over the past 200 k.y. in the equatorial Atlantic: A first estimate",2000,"10.1130/0091-7613(2000)28<499:DPVOTP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034432077&doi=10.1130%2f0091-7613%282000%2928%3c499%3aDPVOTP%3e2.0.CO%3b2&partnerID=40&md5=e8adad98df104adecebb305758f65d1a","Dimethylsulfide (DMS) released from phytoplankton produces cloud condensation nuclei in the marine troposphere, thereby providing a climate-regulating mechanism by increasing cloud albedo. A 200-k.y.-long sedimentary record from the equatorial Atlantic of DMS-producing phytoplankton suggests that DMS production increased during the glacial stages, thus potentially working to further cool the glacial world. Important factors limiting the operation of this possible feedback mechanism for planetary cooling may be the strength of trade winds and the availability of fine, iron-rich dust needed to fertilize growth of DMS producers."
"35271218500;","'Global Warming': New Perspectives from Palaeoecology and Solar Science",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749125659&partnerID=40&md5=474c39417b5948fbb91c9c4d8a9b1ef6","There is considerable public and media interest in the possible impact of human activities on global climate, but many popular accounts ignore remaining uncertainties in both theory and prediction. Undisputed aspects of climate change are presented first, before evidence from recent research into past environments is introduced to expose some common misconceptions over 'global wanning'. Ideas on climate change continue to evolve: new findings in solar science imply that solar activity has an impact upon climate, and suggest an amplifying mechanism for solar forcing of natural climate change; whilst new evidence and ideas in both solar science and palaeoecology emphasise the possible importance of external (solar) forcing in the Late-Holocene, and point to reappraisal of the relative roles of clouds, water vapour and CO2 in climate change. The accumulating palaeoclimate data, and continuing development of ideas regarding the roles of both the sun and clouds, imply greater uncertainty over the direction, rate and magnitude of future climate change than is widely appreciated. Geography © 1998."
"6603226359;","Accuracy assessment of temporal and spatial up-scaling or IR rain cloud duration techniques",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034426924&partnerID=40&md5=cec1b552f40c68c79c712a9513cc4bdc","Analysis of spatial and temporal sensitivity of the IR rain cloud duration (RCD) methods are presented. It is shown that the remote sensing based rainfall algorithms provide the best fit to aggregated rainfall data over periods of approximately six days inside user defined areas of homogenous climatic zones. Also presented is a simple use of microwave brightness temperature data, to separate large areas into homogenous climatic zones and improve RCD rainfall estimates significantly."
"22934023200;","Variability in the cloud cover of the Karkonosze Mountains over the last century",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034456458&partnerID=40&md5=33f073d3f1182a340db90a8c10bbbcfe","The study details an analysis of cloudiness conditions over Śniezka Mountain in the years 1885-1995. The basis for this constituted timed observations (at 7, 13 and 21 hrs) of cloud cover and mean daily cloud amount in particular months, seasons and the whole year, as well as the number of clear, overcost and foggy days. The variability to cloud cover was found to feature an upward trend of 0.4/100 years which is most clearly seen in the autumn quarter. There is a tendency for the number of clear days to decrease (by 22 days/100 years), and for the number of days with fog to increase, most especially in winter (10.4 days/100 years). A link between cloud cover and the frequency of occurrence of the western-circulation macrotype has been noticeable in the last 40 years."
"7004468578;55684491100;","European lighting nitrogen oxides project (EULINOX)",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034512371&partnerID=40&md5=be795d66bb3bcfc4380d9074f42764b3","This volume contains the final report of the 'European Lightning Nitrogen Oxides Project' (EULINOX) which was supported (1998-1999) by the European Commission's Environment and Climate Programme implemented under the Fourth Framework Programme. The general objective of the EULINOX project was to use new experimental evidence for a reexamination of the lightning NO x (LNO x) production and thus to provide an improved knowledge of the distribution of NO x sources on the European scale. The objective was addressed by a field experiment and modelling studies both at regional scale (in Southern Germany) and at the scales of Western Europe. Airborne measurements in storm anvils demonstrated that there exists a large variation in the LNO x content according to the cloud size and degree of electrical activity. In smaller storms, which produce no or only a few flashes, most of the NO x observed in the anvil originates from the boundary layer and is lifted to upper levels within the storm updrafts. In extreme cases the NO x produced by lighting can amount up to as much as 95% of the total NO x content measured in the anvil. The EULINOX findings support the recently discussed hypothesis claiming that intra-cloud flashes can be as efficient NO x producers as are cloud-to-ground flashes. The representation of NO x production from lighting within cloud-scale and chemistry transport models could be improved."
"6603227814;7004344921;16678242800;","Observation and modelling of water balance components in Northern Fennoscandia with NOAA-AVHRR and SPOT VEGETATION imagery",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034426688&partnerID=40&md5=32cb0c4e29e0605b861f2bbbe24c43a8","NOAA-AVHRR and SPOT VEGETATION imagery is being used for parameterization and validation of a large-scale hydrological model of Northern Fennoscandia. Due to SPOT VEGETATION's spectral observations at 1.6 μm, snow can easily be discriminated from clouds. The thermal bands of the NOAA satellites will be used to assess spatial patterns of evapotranspiration."
"57207507371;","The impact of the world's transport aircraft flights on the ozonosphere and climate",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034439633&partnerID=40&md5=ff6175eb082f1f238831854e70187289","The results of studies of current and future expected effects of aircraft engine exhausts on the atmospheric gas and aerosol composition and Earth's climate are presented and reviewed. An evaluation is made of the burnt fuel along the main flight corridors and of exhaust emissions in the 1990s, as well as of their present and expected rapid increase until 2050. The main ways of emission effects are indicated and analyzed for the current subsonic and developing supersonic transport aviation. These are changes in the content of radiatively active gases in the upper troposphere and lower stratosphere and the effect of condensation trails on the upper-air clouds. Model estimates of the current low levels of these effects are presented along with possible causes of their poor detection. The technological and organizational measures for lowering atmospheric effects of aircraft emissions are also indicated."
"7003291328;7003957736;7403076976;","The global atmospheric electric circuit, solar activity and climate change",2000,"10.1016/S1364-6826(00)00112-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034483361&doi=10.1016%2fS1364-6826%2800%2900112-7&partnerID=40&md5=52a636e5d3db4024b434c6a50c072bef","The study of the global atmospheric electric circuit has advanced dramatically in the past 50 years. Large advances have been made in the areas of lightning and thunderstorm research, as related to the global circuit. We now have satellites looking down on the Earth continuously, supplying information on the temporal and spatial variability of lightning and thunderstorms. Thunderstorms are electric current generators, which drive electric currents up through the conducting atmosphere. They maintain the ionosphere at a potential of Ο-250 kV with respect to the Earth's surface. The global electric circuit is completed by currents Ο2 pA/m2 flowing through the fair weather atmosphere, remote from thunderstorms, and by transient currents due to negative cloud-to-ground lightning discharges. The time constant of the circuit, Ο &gt; 2 min, demonstrates that thunderstorms must occur continually to maintain the fair weather electric field. New discoveries have been made in the field of sprites, elves and blue jets, which may have a direct impact on the global circuit. Our knowledge of the global electric circuit modulated by solar effects has improved. Changes to the global circuit are associated with changes of conductivity linked with the time-varying presence of energetic charged particles, and the solar wind may influence the global electric circuit by inferred effects on cloud microphysics, temperature, and dynamics in the troposphere. We now have a better understanding of how the conductivity of the atmosphere is influenced by aerosols, and how this impacts our measurements of the fair-weather global circuit. The global atmospheric electric circuit is also beginning to be recognised by some climate researchers as a useful tool with which to study and monitor the Earth's changing climate. © 2000 Elsevier Science Ltd. All rights reserved."
"7006450978;55684491100;","The European lightning nitrogen oxides project (EULINOX)",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749227239&partnerID=40&md5=efbcfb464e4d28ea21b288d7a2e6944d","This volume contains the final report of the 'European Lightning Nitrogen Oxides Project' (EULINOX) which was supported (1998-1999) by the European Commission's Environment and Climate Programme implemented under the Fourth Framework Programme. The general objective of the EULINOX project was to use new experimental evidence for a reexamination of the lightning NO x (LNO x) production and thus to provide an improved knowledge of the distribution of NO x sources on the European scale. The objective was addressed by a field experiment and modelling studies both at regional scale (in Southern Germany) and at the scales of Western Europe. Airborne measurements in storm anvils demonstrated that there exists a large variation in the LNO x content according to the cloud size and degree of electrical activity. In smaller storms, which produce no or only a few flashes, most of the NOX observed in the anvil originates from the boundary layer and is lifted to upper levels within the storm updrafts. In extreme cases the NO x produced by lightning can amount up to as much as 95% of the total NO x content measured in the anvil. The EULINOX findings support the recently discussed hypothesis claiming that intra-cloud flashes can be as efficient NO x producers as are cloud-to-ground flashes. The representation of NO x production from lightning within cloud-scale and chemistry transport models could be improved."
"56673482900;8321530600;","Validation of passive microwave snow algorithms",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034427113&partnerID=40&md5=fe37fe38f6c171294e02e73d964e6b62","Passive microwave satellite remote sensing can greatly enhance large-scale snow measurements based on visible satellite data alone because of the ability to acquire data through clouds or during darkness as well as to provide a measure of snow depth or water equivalent (SWE). This study develops a validation methodology and provides preliminary results from comparisons of several different passive microwave algorithms, including both mid- and high-frequency channels, vertical and horizontal polarizations and polarization difference approaches. Snow extent derived from passive microwave data is compared with the NOAA Northern Hemisphere snow charts. Results clearly indicate those time periods and geographical regions where the two techniques agree and where they tend to consistently disagree. Validation of SWE derived from passive microwave data is undertaken using measurements from snow course transects in the former Soviet Union. Preliminary results indicate a general tendency for nearly all of the algorithms to underestimate SWE."
"7005808242;7003543851;","Water vapor feedback and global warming",2000,"10.1146/annurev.energy.25.1.441","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034510138&doi=10.1146%2fannurev.energy.25.1.441&partnerID=40&md5=a1dab5b6b496b385391f4b91437f22d1","Water vapor is the dominant greenhouse gas, the most important gaseous source of infrared opacity in the atmosphere. As the concentrations of other greenhouse gases, particularly carbon dioxide, increase because of human activity, it is centrally important to predict how the water vapor distribution will be affected. To the extent that water vapor concentrations increase in a warmer world, the climatic effects of the other greenhouse gases will be amplified. Models of the Earth's climate indicate that this is an important positive feedback that increases the sensitivity of surface temperatures to carbon dioxide by nearly a factor of two when considered in isolation from other feedbacks, and possibly by as much as a factor of three or more when interactions with other feedbacks are considered. Critics of this consensus have attempted to provide reasons why modeling results are overestimating the strength of this feedback. Our uncertainty concerning climate sensitivity is disturbing. The range most often quoted for the equilibrium global mean surface temperature response to a doubling of CO2 concentrations in the atmosphere is 1.5 °C to 4.5 °C. If the Earth lies near the upper bound of this sensitivity range, climate changes in the twenty-first century will be profound. The range in sensitivity is primarily due to differing assumptions about how the Earth's cloud distribution is maintained; all the models on which these estimates are based possess strong water vapor feedback. If this feedback is, in fact, substantially weaker than predicted in current models, sensitivities in the upper half of this range would be much less likely, a conclusion that would clearly have important policy implications. In this review, we describe the background behind the prevailing view on water vapor feedback and some of the arguments raised by its critics, and attempt to explain why these arguments have not modified the consensus within the climate research community."
"56224608000;7003880605;6504808941;","Monitoring wetland hydrology in Atlantic Canada using multi-temporal and multi-beam Radarsat data",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034427140&partnerID=40&md5=3dbae90040f17e6940505976c8e3c2ca","Wetland complexes comprise a large percentage of ground cover in central Labrador, Canada, and contain some of the largest peatlands in North America. The region experiences long cold winters and short cool summers, resulting in a limited growth period. Fens and bogs are the dominant wetland types. The level of moisture saturation, chemistry, topography and climate influence the development of wetland systems. Slight changes in these environmental factors can significantly alter vegetation species and health. As persistent cloud cover often limits the utility of optical remotely sensed data in Atlantic Canada, the value of using the all-weather capabilities of radar data become evident. Temporal sequences of Radarsat images were acquired in May, June and August 1999. During each time period, four Radarsat scenes with incidence angles spanning 20-49° (Standard 1, 4, 7 and Fine 1) were acquired. This paper describes changes in radar backscatter as a function of incidence angle, vegetation structure and moisture conditions."
"7202559581;7202155374;","A generalized algorithm for retrieving cloudy sky skin temperature from satellite thermal infrared radiances",2000,"10.1029/2000JD900318","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034490773&doi=10.1029%2f2000JD900318&partnerID=40&md5=24193159f8b6a6d6a7b5eb5309abb10b","A physical algorithm for calculating cloudy pixel skin temperature from its neighboring clear pixels is proposed generalizing that of Jin [2000]. Two neighboring pixels over the same land cover have a difference in temperature largely explained by surface insolation. Hence this algorithm starts from the surface energy balance equation (SEB) and expresses each energy term of SEB as a function of skin temperature. Then SEB is solved to derive cloudy pixel skin temperature from neighboring clear skin temperature plus a correction term determined by surface insolation, air temperature, and wind speed. This algorithm can be used for nights and winter hemisphere high latitudes where there is no surface insolation and is applicable to any surface where the principle of SEB is applicable. The algorithm is evaluated by using FIFE and BOREAS field experiments. Its global application has been examined through simulations with the NCAR Community Climate Model (CCM) coupled with the Biosphere-Atmosphere Transfer Scheme (BATS) simulations. The accuracy of the algorithm is encouraging: the rms error at a monthly pixel level is 1-2 K. Observed errors are greater when there is precipitation. Copyright 2000 by the American Geophysical Union."
"7004360653;57203400519;7403917238;","Geometrically effective cloud fraction for solar radiation",2000,"10.1016/S0169-8095(00)00060-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033786368&doi=10.1016%2fS0169-8095%2800%2900060-0&partnerID=40&md5=61f2660afabebf394928ccbc757dfa1c","It has been suggested in the past that an 'effective' cloud fraction can be used to take into account cloud geometry effects in solar radiation parameterizations. All such models have been based on the reflected flux from non-plane-parallel cloud fields. In this study, it is shown that the 'effective' cloud fraction based on absorption (or transmission) could differ considerably from that based on reflection and, moreover, is not constant throughout the solar spectrum even for fixed cloud geometry. Furthermore, the representation of cloud radiative forcing at the surface and at the top of the atmosphere in terms of cloud fractions are based on different 'effective' cloud fractions. Therefore, a simple interpretation of measured values of the forcing ratio is not possible when geometric effects are present. (C) 2000 Elsevier Science B.V. All rights reserved."
"6602811538;57202163835;7003941060;","Ocean-atmosphere interactions and climate drift in a coupled general circulation model",2000,"10.1007/s003820000073","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033814797&doi=10.1007%2fs003820000073&partnerID=40&md5=6fba504a89ba2f4ceabed53e9abb827d","We have analysed numerical simulations performed with a global 3D coupled atmosphere-ocean model to focus on the role of atmospheric processes leading to sea surface temperature (SST) drift in the tropics. Negative SST errors occur coherently in space and time with large positive errors in latent heat and momentum fluxes at the tropical air-sea interface, as diagnosed from forced SST simulations. The warm pool in the western Pacific disappears after a few years of simulation. Strong SST gradients enforce regions of high precipitation that are thin and stationary north of the equator. We detail the implications for the ocean-atmosphere system of such upheaval in the deep convection location. A sensitivity experiment to empirically formulate air-sea drag coefficient shows that the rapid warm pool erosion is not sensitive to changes in the formulation of the surface drag coefficient over the oceans because the corresponding changes in turbulent heat fluxes and LW cooling approximately cancel one another. In the eastern Pacific, the improvement in SST is striking and caused by feedbacks between SST, surface turbulent fluxes and boundary layer cloud fraction, which decreases as SST warms."
"7003591311;7005968859;","Does cloud processing of aerosol enhance droplet concentrations?",2000,"10.1029/2000JD900369","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033674609&doi=10.1029%2f2000JD900369&partnerID=40&md5=76d092de43f4d069bee3939d786687d8","In this paper we explore phase space for cloud processing of cloud condensation nuclei (CCN) via heterogeneous chemistry. A range of input CCN size spectra, parameterized as lognormal distributions, are used as input to a parcel model driven along trajectories derived from a large-eddy simulation of the stratocumulus-capped marine boundary layer. A simple sulfate chemistry model is coupled to the microphysical model. Gas phase concentrations of SO2, O3, H2O2, and NH3 are varied so as to generate one case for which SO2 processing is dominated by oxidation via O3 and another case for which processing is dominated by oxidation via H2O2. The processed aerosol spectra are then used as input to an adiabatic parcel model that predicts the drop concentration for a given updraft velocity. Comparisons are made between predictions of drop concentration based on input of aerosol spectra that have experienced processing and an equivalent set that has not experienced processing. It is shown that for both of the chemical processing scenarios, heterogeneous processing can either enhance or suppress the number of drops activated in the subsequent cloud cycle, depending on the input CCN distribution and the magnitude of the updraft. Enhancement of drop concentration occurs in cases where the subsequent cloud cycle has low vertical velocity. A reduction in drep number occurs when updraft velocities in the subsequent cloud cycle are high. The size of the smallest CCN size category activated in the subsequent cloud cycle, relative to that experienced in the original cloud cycle, is important in determining the change in number of activated drops. By applying probability distribution functions of the vertical velocity, we calculate that, on average, drop concentrations are likely to be enhanced by between 10% and 20% for the cases examined. Nevertheless, the potential for both positive and negative changes in drop concentration due to cloud processing may complicate predictions of the indirect effect of aerosols on climate. Copyright 2000 by the American Geophysical Union."
"6602548487;15082690700;7005088845;57189523812;35420173900;","Single particle analysis of aerosols, observed in the marine boundary layer during the Monterey area ship tracks experiment (MAST), with respect to cloud droplet formation",2000,"10.1023/A:1006416600722","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033795385&doi=10.1023%2fA%3a1006416600722&partnerID=40&md5=72a5d62f03ca9c49c8bd937484850122","The chemical composition of individual particles >0.2 μm sampled during the MAST-experiment were analysed by SEM-EDX, in combination with multivariate techniques. The objective of this experiment was to identify the mechanisms responsible for the modification of marine stratocumulus clouds by emissions from ships and in a wider sense to provide information on the global processes involved in atmospheric modification of cloud albedo. Aerosols were examined under different MBL pollution levels (clean, intermediately polluted and moderately polluted) in five different reservoirs: background below-cloud and above-cloud aerosol; background cloud droplet residual particles; below-cloud ship plume aerosol and ship track cloud droplet residual particles. In this study a relation was provided between the aerosol emitted from the ship's stack to an effect in cloud. Additionally, a large fraction of the ambient aerosol was found to be composed of organic material or other compounds, consisting of low Z-elements, associated with chlorine. Their number fraction was largest in clean marine boundary layers, and decreased with increasing pollution levels. The fraction of 'transformed sea salt' (Na, Cl, S), on the other hand, increased with the pollution level in the MBL. Only 20% of the particles fell within the detectable range of the analysis."
"7006235116;7201443806;7004427298;6506201895;","Enso and climatic signals across the Indian Ocean basin in the global context: Part I, Interannual composite patterns",2000,"10.1002/1097-0088(200009)20:11<1285::AID-JOC536>3.0.CO;2-R","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033835011&doi=10.1002%2f1097-0088%28200009%2920%3a11%3c1285%3a%3aAID-JOC536%3e3.0.CO%3b2-R&partnerID=40&md5=07534f1dc2b4f519a535cc238fae9c90","This study focuses on the interplay between mean sea level pressure (MSLP), sea surface temperature (SST), and wind and cloudiness anomalies over the Indian Ocean in seasonal composite sequences prior to, during, and after strong, near-global El Nino and La Nina episodes. It then examines MSLP and SST anomalies in the 2-2.5-year quai-biennial (QB) and 2.5-7-year low-frequency (LF) bands that carry the bulk of the raw ENSO signal. Finally, these fields were examined in conjunction with patterns of correlations between rainfall and joint spatiotemporal empirical orthogonal function (EOF) time series band pass filtered in the QB and LF bands. The seasonal composites indicate that the El Nino-1 (La Nina-1) pattern tends to display a more robust and coherent (weaker and less organized) structure during the evolution towards the mature stage of the event. The reverse tends to be apparent in the cessation period after the peak phase of an event, when El Nino events tend to collapse quite quickly. Climatic variables over the Indian Ocean Basin linked to El Nino and La Nina events show responses varying from simultaneous, to about one season's lag. In general, SSTs tend to evolve in response to changes in cloud cover and wind strength over both the north and south Indian Ocean. There are also strong indications that the ascending (descending) branch of the Walker circulation is found over the African continent (central Indian Ocean) during La Nina phases, and that the opposite configuration occurs in El Nino events. These alterations are linked to distinct warm-cool (cool-warm) patterns in the north-south SST dipole over the western Indian Ocean region during the El Nino (La Nina) events. An examination of MSLP and SST anomaly patterns in the QB and LF bands shows that signals are more consistent during El Nino-1 and El Nino sequences than they are during La Nina-1 and La Nina sequences. The QB band has a tendency to display the opposite anomaly patterns to that seen on the LF band during the early stages of event onset, and later stage of event cessation, during both El Nino-Southern Oscillation (ENSO) phases. El Nino events tend to be reinforced by signals on both bands up to their mature phase, but are then seen to erode rapidly, as a result of the presence of distinct La Nina anomalies on the QB band after their peak phase. During La Nina events, the opposite is observed during their cessation phase. Both QB and LF bands often display SST dipole anomalies that are not clearly evident in the raw composites alone. An eastern Indian Ocean SST dipole shows a tendency to occur during the onset phase of particular El Nino or La Nina episodes, especially during the austral autumn-winter (boreal spring-summer) and, when linked to tropical-temperate cloud bands, can influence Australian rainfall patterns. Analyses of seasonal correlations between rainfall and joint MSLP and SST EOF time series on QB and LF bands and their dynamical relationship with MSLP and SST anomalies during El Nino and La Nina events, show that the interplay between atmospheric circulation and SST anomalies dictates the observed rainfall regimes are evident. This ability to discriminate the finer structure of physical relationships, correlations and patterns provides a deeper insight into Indian Ocean responses to ENSO phases. Copyright (C) 2000 royal Meteorological Society."
"7004280722;6602115663;57203142176;57194045072;","Impacts of the ocean lateral diffusion on the El Niño/Southern Oscillation-like variability of a global coupled General Circulation Model",2000,"10.1029/1999GL011323","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033625901&doi=10.1029%2f1999GL011323&partnerID=40&md5=5d50ee9c191e9e270d1b0c26204dfb6a","A global coupled General Circulation Model is used to investigate effects of the lateral ocean mixing on the amplitude and spectral characteristics of the ENSO-like variability. Three 40-year coupled simulations are analysed. They only differ by the lateral ocean physics parametrized: a horizontal diffusion scheme; an isopycnal scheme ; isopycnal scheme with an Eddy Induced Velocity (EIV) term. The Multichannel Singular Spectrum Analysis is used to extract linear modes of variability from each simulation and from observations. The strength of the variability, close to that observed in the horizontal and only-isopycnal simulations, is stronger in the two isopycnal configurations, and more especially when the EIV is added. The dominant periods of the variability, also close to those observed, are also affected by the lateral diffusion: the time scale becomes slightly longer as the complexity of the lateral physics increases. Copyright 2000 by the American Geophysical Union."
"35518083800;7004309625;7005605341;","Cloudiness variations over the former Soviet Union",2000,"10.1002/1097-0088(200008)20:10<1097::AID-JOC541>3.0.CO;2-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033812936&doi=10.1002%2f1097-0088%28200008%2920%3a10%3c1097%3a%3aAID-JOC541%3e3.0.CO%3b2-5&partnerID=40&md5=7ee97d35f29068da11f91a9381d5a7bf","In the former Soviet Union (FUSSR), low-level cloud cover has significantly decreased over the period 1936-1990. This change has an opposite sign to that of the total cloud cover. Analysis of the occurrences of cloud types suggests that the decrease in low-level cloud cover was primarily due to the decrease in stratiform clouds. The presence of stratiform clouds is generally related to atmospheric static stability and/or frontal system passages. Thus, the reported decrease in occurrence of these clouds could be caused by weakened atmospheric stability and/or circulation associated with the increase in surface air temperature and reduction of the meridional temperature gradient. A spectacular increase in cumulus clouds over the FUSSR has been discovered over the past several decades. This increase (being supported by a significant increase of cirrus clouds) is a manifestation of intensified convective processes over Northern Eurasia in the second half of the 20th century, and is consistent with the observed increase in heavy precipitation. While over the European part of the FUSSR the increase in heavy precipitation (above 20 mm/day) is a part of the general increase in annual and summer precipitation totals over the past century and/or past 50 years, a statistically significant increase in heavy precipitation in Siberia has occurred when the precipitation frequency and totals declined over the past 60 years. The present findings (increase in cumulus and decrease in stratiform clouds) explain these phenomena. Changes in total cloud cover, and particularly in its components, indicate that cloud interaction with other climate variables is changing somewhat. Therefore, it would be important to extend this study to other regions of the globe when more related data are available. Copyright (C) 2000 Royal Meteorological Society."
"57197944069;23102706500;6601992039;","A 5-year climatology of the solar erythemal ultraviolet in Athens, Greece",2000,"10.1002/1097-0088(200008)20:10<1237::AID-JOC532>3.0.CO;2-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033817611&doi=10.1002%2f1097-0088%28200008%2920%3a10%3c1237%3a%3aAID-JOC532%3e3.0.CO%3b2-3&partnerID=40&md5=f74533a02a19b7a08d64abf52acb5b50","Observations of solar ultraviolet (UV) irradiance in Athens for the period 1993-1997 employing the Yankee Environmental Systems (YES) pyranometer (model UVB-1) are analysed to provide a climatological description of the erythemally active UV component in this urban Mediterranean environment. The role of cloud cover and the ozone column in the determination of the UV climate are estimated by a comparison of the record of UV irradiance with daily observations of total ozone at the University of Athens and of total solar radiation at the National Observatory of Athens. During the warmer months, June to September, there appears to be a substantial reduction of solar UV by atmospheric components other than ozone and clouds, a conclusion that is supported by comparing the observations with the predictions of radiative transfer models and with UV observations in a rural southern hemisphere environment reported by McKenzie et al. (1991). Copyright (C) 2000 Royal Meteorological Society."
"6701596624;55896920900;6603892183;7005550877;6701323933;6603100667;7404369915;35551238800;6602107874;7006211890;57197784699;7102661133;6701599239;7006577245;56706602500;","Microphysical and radiative properties of stratocumulus clouds: The EUCREX mission 206 case study",2000,"10.1016/S0169-8095(00)00058-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6744248663&doi=10.1016%2fS0169-8095%2800%2900058-2&partnerID=40&md5=5d3b24bbdc3707fae1695c699e54f5ac","In this conclusion paper, remote sensing retrievals of cloud optical thickness performed during the EUCREX mission 206 are analyzed. The comparison with estimates derived from in situ measurements demonstrates that the adiabatic model of cloud microphysics is more realistic than the vertically uniform plane parallel model (VUPPM) for parameterization of optical thickness. The analysis of the frequency distributions of optical thickness in the cloud layer then shows that the adiabatic model provides a good prediction when the cloud layer is thick and homogeneous, while it overestimates significantly the optical thickness when the layer is thin and broken. Finally, it is shown that the effective optical thickness over the whole sampled cloud is smaller than the adiabatic prediction based on the mean geometrical thickness of the cloud layer. The high sensitivity of the optical thickness on cloud geometrical thickness suggests that the effect of aerosol and droplet concentration on precipitation efficiency, and therefore on cloud extent and lifetime, is likely to be more significant than the Twomey effect. (C) 2000 Elsevier Science B.V. All rights reserved."
"55896920900;6603892183;","Introduction to the EUCREX-94 mission 206",2000,"10.1016/S0169-8095(00)00053-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033850677&doi=10.1016%2fS0169-8095%2800%2900053-3&partnerID=40&md5=9249f78a4c87555b708535b73402ce7b","Part of the EUCREX-94 experiment was devoted to the study of the radiative properties of boundary layer clouds in relation with their microphysical and structural properties. Mission 206, on April 18, is particularly attractive because of a general trend in cloud geometrical thickness within the sampled region, with corresponding values of optical thickness between 4 and 70. The cloud system has been extensively documented in situ with an instrumented aircraft, while two other aircraft were measuring its radiative properties with radiometers and a lidar. This paper introduces the scientific objectives of the experiment and describes the instrumental setup. After a presentation of the meteorological situation, the various papers of this series are briefly introduced. (C) 2000 Elsevier Science B.V. All rights reserved."
"7003821079;7005729142;","Use of Doppler radar to assess ice cloud particle fall velocity-size relations for remote sensing and climate studies",2000,"10.1029/2000JD900353","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033766417&doi=10.1029%2f2000JD900353&partnerID=40&md5=df11a206e889379e50e7120728dad831","Knowledge of ice crystal terminal velocities, both for individual crystals and for size distributions, is important for an adequate representation of ice particle sedimentation in climate models. While the terminal velocities (v1) of individual crystals of simple shapes have been measured, theoretical relations of the form v1 = ADB (where D is the maximum particle dimension), obtained using expressions for the aerodynamic drag force, are often more useful because they can be applied to a wide range of particle sizes and heights and temperatures in the atmosphere. For high tropospheric ice clouds the coefficient A has been found to vary over 1 order of magnitude; the exponent B is generally within the range 0.7-1.4. Aerodynamic drag force calculations show that A and B are related. A and B can also be used to characterize terminal-velocity-particle characteristic size relations for size distributions. In this study we use collocated, vertically pointing measurements of ice cloud radar reflectivity, Doppler velocity, and IR brightness temperatures to estimate the vertical profiles of cloud particle characteristic size, cloud ice water content, and vertically averaged value of the coefficient A, emphasizing cirrus clouds. We analyze variations in terminal-velocity-size relations for individual particles and corresponding variations for ensembles of particles: for example, in relations between the reflectivity-weighted terminal velocity and the median volume size and between the mass-weighted terminal velocity and the median volume size. The retrievals indicate that A ranges from ∼250 to almost 4000 (cgs units), similar to the range found from the theoretical calculations. The coefficient A tends to decrease as a characteristic particle size (e.g., median size) increases. As a simplification for climate modeling efforts, we present an empirical relation between median size and A, although there is a fair amount of variability about this relation. Using the Doppler measurements and retrieval data, we also derive relations between the mass-weighted terminal velocity and cloud ice water content. Such relations are useful for representing fallout of ice particles in climate and cloud-resolving models. Copyright 2000 by the American Geophysical Union."
"7006240152;55905970100;","The clear-sky index to separate clear-sky from cloudy-sky situations in climate research",2000,"10.1029/2000GL011743","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034352598&doi=10.1029%2f2000GL011743&partnerID=40&md5=438a2947432602d8ad0aa7779b86e7c3","Accurate surface radiation fluxes are required to quantify atmosphere-surface energy exchanges. In climate research, detailed investigations of the influence of diverse atmospheric conditions on radiative fluxes ask for a well-defined distinction between clear-sky and cloudy-sky situations. Effects of clouds, the so called 'cloud forcing', can only be determined by explicitly separating clear-sky from all-sky radiation measurements. A Clear-Sky Index (CSI) to separate clear-sky from cloudy-sky situations has therefore been introduced, using accurate atmospheric longwave radiation in conjunction with air temperature and humidity measurements at the station. This clear-sky index, which has the important advantage to be applicable 24 hours a day, was tested and first used on measurements of the Alpine Surface Radiation Budget (ASRB) network, and was of prime importance for the determination of the altitude dependence of cloud forcing and greenhouse effect over the Alps."
"7004764167;7406514318;","The time-dependence of climate sensitivity",2000,"10.1029/2000GL011373","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034352606&doi=10.1029%2f2000GL011373&partnerID=40&md5=34f71f376e48e9657903301af6543e5f","A doubled CO<inf>2</inf> coupled ocean-atmosphere experiment has been run for over 800 years. The 'effective' equilibrium climate sensitivity to a doubling of CO<inf>2</inf> (the equilibrium response of the model assuming the feedbacks remained constant at the value found at any given point of the transient response) is calculated throughout the run and found to increase by around 40%. The time-dependence is associated with differences in cloud feedback arising from inter-hemispheric temperature differences due to the slower warming rate of the Southern Ocean. The time-dependence of the climate response has implications for the use of simpler models in scaling GCM results to different scenarios of forcing."
"55730602600;22946301100;6602568741;6701803760;55905504600;6603745877;35568326100;7005421048;6602215448;6603366480;6701490421;7005433221;10143908900;7102113229;7006577245;7101973570;6601983967;7004307916;55866604100;7102132806;7006784145;","European aerosol research lidar network to establish an aerosol climatology (EARLINET)",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034271351&partnerID=40&md5=6231058e75b93f956daab4e7287de829","Aerosols play a major role in the global climate system and in atmospheric chemistry. They affect the concentrations of other important atmospheric constituents, such as ozone. A method named EARLINET is used to establish a quantitative statistical database of the horizontal, vertical, and temporal distributions of aerosols. It will help in understanding the physical and chemical processes related to these particles, their long-range transport and deposition, and the interaction of aerosols with clouds. The collected data will provide the basis for satellite missions employing laser remote sensing and will be used to improve the quality of a number of satellite retrieval systems."
"7005212820;7004325649;7202208382;6701835010;56268091100;35549146800;","Use of a GCM to explore sampling issues in connection with satellite remote sensing of the Earth radiation budget",2000,"10.1029/2000JD900239","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033784277&doi=10.1029%2f2000JD900239&partnerID=40&md5=4a950745a1239d4cc0fce95027695427","Collocated in time and space, top-of-the-atmosphere measurements of the Earth radiation budget (ERB) and cloudiness from passive scanning radiometers, and lidar- and radar-in-space measurements of multilayered cloud systems, are the required combination to improve our understanding of the role of clouds and radiation in climate. Experiments to fly multiple satellites ""in formation"" to measure simultaneously the radiative and optical properties of overlapping cloud systems are being designed. Because satellites carrying ERB experiments and satellites carrying lidars- or radars-in space have different orbital characteristics, the number of simultaneous measurements of radiation and clouds is reduced relative to the number of measurements made by each satellite independently. Monthly averaged coincident observations of radiation and cloudiness are biased when compared against more frequently sampled observations due, in particular, to the undersampling of their diurnal cycle. Using the Colorado State University General Circulation Model (CSU GCM), the goal of this study is to measure the impact of using simultaneous observations from the Earth Observing System (EOS) platform and companion satellites flying lidars or radars on monthly averaged diagnostics of longwave radiation, cloudiness, and its cloud optical properties. To do so, the hourly varying geographical distributions of coincident locations between the afternoon EOS (EOS-PM) orbit and the orbit of the ICESAT satellite set to fly at the altitude of 600 km, and between the EOS PM orbit and the orbits of the PICASSO satellite proposed to fly at the altitudes of 485 km (PICA485) or 705 km (PICA705), are simulated in the CSU GCM for a 60-month time period starting at the idealistic July 1, 2001, launch date. Monthly averaged diagnostics of the top-of-the-atmosphere, atmospheric, and surface longwave radiation budgets and clouds accumulated over grid boxes corresponding to satellite overpasses are compared against monthly averaged diagnostics obtained from hourly samplings over the entire globe. Results show that differences between irregularly (satellite) and regularly (true) sampled diagnostics of the longwave net radiative budgets are the greatest at the surface and the smallest in the atmosphere and at the top-of-the-atmosphere, under both cloud-free and cloudy conditions. In contrast, differences between the satellite and the true diagnostics of the longwave cloud radiative forcings are the largest in the atmosphere and at the top-of-the atmosphere, and the smallest at the surface. A poorer diurnal sampling of the surface temperature in the satellite simulations relative to the true simulation contributes a major part to sampling biases in the longwave net radiative budgets, while a poorer diurnal sampling of cloudiness and its optical properties directly affects diagnostics of the longwave cloud radiative forcings. A factor of 8 difference in the number of satellite overpasses between PICA705 and PICA485 and ICESAT leads to a systematic factor of 3 difference in the spatial standard deviations of all radiative and cloudiness diagnostics. Copyright 2000 by the American Geophysical Union."
"7102886537;8401913500;","Climate forcings and the initiation of low-latitude ice sheets during the Neoproterozoic Varanger glacial interval",2000,"10.1029/2000JD900221","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644434082&doi=10.1029%2f2000JD900221&partnerID=40&md5=3cdc3af515ab307901cddc7e280e40db","The GISS GCM was used to determine if a diverse set of climate forcings, alone or in combination, could have initiated the low-latitude ice sheets of the Varanger (∼600 Ma) glacial interval. The simulations use a realistic reconstruction of the paleocontinental distribution and test the following forcings, alone and in combination: 6% solar luminosity decrease, four atmospheric CO2 scenarios (1260, 315, 140, and 40 ppm), a 50% increase and a 50% decrease in ocean heat transports, and a change in obliquity to 60°. None of the forcings, individually, produced year-round snow accumulation on low-latitude continents, although the solar insolation decrease and 40 ppm CO2 scenarios allowed snow and ice to accumulate at high and middle latitudes. Combining forcings further cools the climate: when solar luminosity, CO2, and ocean heat transports were all decreased, annual mean freezing and snow accumulation extended across tropical continents. No simulation would have initiated low-latitude glaciation without contemporaneous glaciation at higher latitudes, a finding that matches the distribution of glacial deposits but which argues against high obliquity as a cause of the Varanger ice age. Low-level clouds increased in most scenarios, as did surface albedo, while atmospheric water vapor amounts declined; all are positive feedbacks that drive temperatures lower. In the most severe scenario, global snow and ice cover increased to 68%, compared to 12% under modern conditions, and water vapor dropped by 90%. These results do not necessarily preclude a ""snowball"" Earth climate scenario for the Varanger glacial interval. However, either more severe forcings existed or radical changes occurred in the ocean/atmosphere system which are unaccounted for by the GCM. Also, as sea ice extent increased in these experiments, snow accumulation began to decline, because of an increasingly dry atmosphere. Under snowball Earth conditions, glaciation would be impossible, since the hydrological cycle would all but cease if the atmosphere's primary moisture source were cut off. Copyright 2000 by the American Geophysical Union."
"35572014900;6603451961;6604098421;7006630889;","Radiative forcings and global warming potentials of 39 greenhouse gases",2000,"10.1029/2000JD900241","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033784239&doi=10.1029%2f2000JD900241&partnerID=40&md5=64fc5ed2e97d844e783368153e129475","The radiative forcings and global warming potentials for 39 greenhouse gases are evaluated using narrowband and broadband radiative transfer models. Unlike many previous studies, latitudinal and seasonal variations are considered explicitly, using distributions of major greenhouse gases from a combination of chemical-transport model results and Upper Atmosphere Research Satellite (UARS) measurements and cloud statistics from the International Satellite Cloud Climatology Project. The gases examined include CO2, CH4, N2O, plus a number of chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, hydrochlorocarbons, bromocarbons, iodocarbons, and perfluorocarbons (PFCs). The model calculations are performed on a 5° latitude grid from 82.5° S to 82.5° N. The radiative forcings determined by the model are then used to derive global warming potential for each of the compounds, which are compared with prior analyses. In addition, the latitudinal and seasonal dependence of radiative forcing since preindustrial time is calculated. The vertical profiles of the gases are found to be important in determining the radiative forcings; the use of height-independent vertical distributions of greenhouse gases, as used in many previous studies, produce errors of several percent in estimated radiative forcings for gases studied here; the errors for the short-lived compounds are relatively higher. Errors in evaluated radiative forcings caused by neglecting both the seasonal and the latitudinal distributions of greenhouse gases and atmospheres are generally smaller than those due to height-independent vertical distributions. Our total radiative forcing due to increase in major greenhouse gas concentrations for the period 1765-1992 is 2.32 Wm-2, only 2% higher than other recent estimates; however, the differences for individual gases are as large as 23%. Copyright 2000 by the American Geophysical Union."
"7006550762;7005117153;7402959242;","Modeled impact of cirrus cloud increases along aircraft flight paths",2000,"10.1029/1999JD901160","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033794515&doi=10.1029%2f1999JD901160&partnerID=40&md5=fa24be4215364eb679b6301f55d6f362","The potential climate impact of contrails and alterations in the lifetime of background cirrus due to subsonic aircraft water and aerosol emissions has been investigated in a set of experiments using the GISS GCM connected to a q-flux ocean. Cirrus clouds at a height of 12-15 km, with an optical thickness of 0.33, were input to the model ""x"" percentage of clear-sky occasions along subsonic aircraft flight paths. The percentage x is varied from 0.05 to 6%. Two types of experiments were performed: one with the percentage of cirrus cloud increase independent of flight density along the flight paths, the other with the percentage related to the density of fuel expenditure. The overall climate impact was similar with the two approaches, due to the feedbacks of the climate system. Fifty years were run for each of the eight experiments, with the following conclusions based on the stable results from years 31-50. The equilibrium global mean response shows that altering high-level clouds by 1% changes the global mean temperature by 0.43° C. The global temperature response is highly linear (linear correlation coefficient of 0.996) for high cloud cover changes between 0.1 and 5%. The warming is amplified in the Northern Hemisphere, more so with greater cloud cover change. The temperature effect maximizes around 10 km, more so as the overall warming increases (warming greater than 4°C occurs there with a 4.8% increase in upper level clouds). The surface temperature response is dominated by the feedbacks and shows little geographic relationship to the high cloud input outside of the hemispheric difference. Considering whether these effects would be observable, changing upper level cloud cover by as little as 0.4% produces warming greater than 2 standard deviations in the microwave sounding unit (MSU) channels 4, 2, and 2r (although the effect would be most noticeable in the upper troposphere channel 3 were standard deviations available). Given estimates of current aircraft impacts, this would require some increase relative to present-day effects, but a signal should be clear given the projections for 2050 aircraft. In comparison to increased CO2 experiments, in these runs the Northern Hemisphere clearly warms more relative to the Southern Hemisphere, and warming due to cloud height changes exceeds that due to the water vapor feedback. Despite the simplified nature of these experiments, the results emphasize the sensitivity of the modeled climate to high-level cloud cover changes and thus the potential ability of aircraft to influence climate by altering clouds in the upper troposphere. Copyright 2000 by the American Geophysical Union."
"7401935940;7102978066;7102335087;7006138888;7202134194;7102570481;56097373000;","A new type of Shipboard Meteorological Satellite Receiving-processing System",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033927642&partnerID=40&md5=103c681307b9d799f879db5edb048edd","The Shipboard Meteorological Satellite Receiving-processing System (SMSRPS) is specially developed for the navigation meteorological safeguard of the Antarctic exploration ship over the sea ice area of the South Ocean. This system can suit to the climate environment of very high temperature - high moisture and very low temperature - supersaturation; it has a self-protection ability to against the hurricane - force wind over force 12 and the strong vibration during icebreaking, as well as strong magnetic disturbance. It has two sets of receiving-imagery processing systems for polar orbit low-resolution and quasi-stationary high-solution satellites. The key creation points of this system are as follows: 1. the active gyro-control stabilization platform and a mixed mounting system of three rotating α - β and x - y axes are used. It solved the tracing difficulties both in the low elevation angle and very high elevation angle of polar-orbit satellite, even in the status of ship moving with continuously changing its position, direction and ship roll and pitch. 2. Imagery processing subsystem. The newest BORLAND-DELPHI language and PASCAL language programming software are used under WINDOWS 95 environment. It has a dynamic positioning nested-grid system and electric mapping grid data system. It can show the latitude-longitude of any point on the map, and marks any object such as ship, station or island, and draws the route. It can monitor cloud and temperature, forest fire, anomalous change of ocean and land. It can output satellite cloud maps of 24 bit with very high clarity. This system is very advanced in technique for the whole structure with the features of small volume, light weight and very low cost. It suits to very bad climate and ocean environment. Its imagery processing system has complete functions with high resolution and being very easy to operate. It is not only suit to land use, but also and specially to all kinds of ship over the sea. It can be extended to domestic and international use. This system played a very important role in the 14th Chinese Antarctic Exploration Navigation, and was introduced a broad attention paid by Chinese newspapers and TV Stations."
"7004500706;56033135100;7003640407;","Global scale palaeoclimate reconstruction of the middle Pliocene climate using the UKMO GCM: Initial results",2000,"10.1016/S0921-8181(00)00028-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033916311&doi=10.1016%2fS0921-8181%2800%2900028-X&partnerID=40&md5=631396e2d054dcad268f40d0e66f05e5","This paper outlines the results of a new climate modelling study for the middle Pliocene (ca. 3 Ma). The work was carried out using the UK Meteorological Office GCM (UKMO, Version 3.0) which is a grid point model using a grid of 2.5°in latitude by 3.75°in longitude. The model utilized the new PRISM2 2°x 2°enhanced data set of boundary conditions for the middle Pliocene supplied by the U.S. Geological Survey's Pliocene Interpretations and Synoptic Mapping Group (PRISM). By comparison with the present, the model simulation predicted a 1.9°C annual mean warming over the globe. Warming was at its greatest in high latitudes and resulted in a reduced equator-to-pole temperature gradient of 6°C and a reduction in the general circulation of the atmosphere. Annual mean values for total precipitation (mm/day) increased by 6% with a minor increase in the high cloud component. In low and equatorial regions, temperature, decreases by a maximum of 8°C (e.g. over East Africa), whilst precipitation increases, associated with a broadening of the Hadley Cell, promoted greater evaporation and further cooling. Comparison of our results with previous modelling studies, which have examined the character of the middle Pliocene climate, reveal a broad pattern of agreement between the models, but with significant differences observed in detail. These differences are caused by: (a) the greater spatial resolution and different physical parameterisations used in the UKMO GCM compared to other models and (b) variations in the PRISM2 data set compared to the original 8°x 10°, or the PRISM1 2°x 2°data set used in earlier modelling studies. Comparison of the simulated palaeoclimate to available geological data shows a broad accordance. However, disparities do exist when examining the apparent strengthening of upwelling suggested by some geological data, against the simulated reduction in strength of the general circulation of the atmosphere predicted by the UKMO GCM. Furthermore, the well-documented uncertainty of the geological record concerning the extent of the East Antarctic ice sheet during the middle Pliocene makes the overall accuracy of the imposed PRISM2 boundary conditions, and hence the predictions of the UKMO GCM, difficult to truly assess. (C) 2000 Elsevier Science B.V."
"8380111100;7202496599;7003683808;","Description and performance of the UIUC 24-layer stratosphere/troposphere general circulation model",2000,"10.1029/2000JD900049","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033789894&doi=10.1029%2f2000JD900049&partnerID=40&md5=d53d059eb5dbf7533953671c87cb09b4","This paper describes the 24-layer stratosphere/troposphere general circulation model (24-L ST-GCM) developed by the Climate Research Group of the University of Illinois at Urbana-Champaign (UIUC). The model's dynamical and physical processes, similar to those of its ancestors, are briefly described. The newly implemented parameterizations of longwave and solar radiation, cloud-radiation interaction, subgrid-scale orographic gravity wave drag, and aerosol radiative forcing are described in more detail. Sensitivity tests using simplified one-dimensional column models and the 24-L ST-GCM are carried out to evaluate these implementations. A 15-year simulation with prescribed climatological sea-surface temperatures and sea-ice extents has been performed. To determine the model's strengths and weaknesses, the simulated results are compared with observations. The model simulates well the geographical distributions of surface-air temperature and precipitation and their seasonal variations. The simulated cloud cover and cloud radiative forcing have the observed magnitudes and latitudinal variations, except near 60° S where the model underestimates the cloud cover by ∼20-30%. It is found that the large-scale cloud distribution and the cloud-top altitude depend on the respective critical relative humidities for the onset of large-scale precipitation and penetrating convection. The model captures reasonably well the observed features of atmospheric temperature and zonal wind in both the stratosphere and troposphere in all seasons, with the exception of the northern stratospheric polar-night jet. The simulated Transformed-Eulerian-Mean residual circulation in the stratosphere has comparable magnitudes and distributions to those obtained by data assimilation and other general circulation models (GCMs). The two-cell Brewer-Dobson circulation is captured. The use of an orographic-type gravity wave drag parameterization is responsible for an abnormally warm northern polar stratosphere in winter, which is contrary to most other GCMs. Copyright 2000 by the American Geophysical Union."
"6602080205;","Effect of cloud inhomogeneity on direct radiative forcing due to aerosols",2000,"10.1029/2000JD900223","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785563&doi=10.1029%2f2000JD900223&partnerID=40&md5=42ab01a4e3aff34e955706c1cbd016b6","The effect of including horizontal cloud inhomogeneity on the direct radiative forcing due to sulphate and soot aerosols is explored. Cloud inhomogeneity is represented using the gamma independent pixel approximation for optical depth. Using a two-stream radiation model, the assumption of plane-parallel clouds normally used in climate models is shown to systematically underestimate the magnitude of the negative radiative forcing due to sulphates and systematically overestimate the positive forcing due to soot aerosol. For overcast skies and a Northern Hemisphere mean aerosol profile, these biases can reach as much as 0.1 W m-2, representing up to 30% of the forcing for sulphates and 5% for soot. The bias introduced in forcing due to sulphate aerosol is much larger than would be expected from the effect of the different albedo produced by altering the treatment of cloud optical depth. For ""global mean"" conditions, considering both clear and cloudy regions, the biases are between 2 and 4% for all three quantities (around 0.04 W m-2 in radiative forcing). This bias can generally be reduced further by constraining the albedo to a fixed (observed) value, thereby using the plane parallel homogeneous approximation with a different (but incorrect) cloud optical depth. The sensitivity of these results to solar zenith angle, cloud properties, surface reflectance, the number of streams used in the radiative transfer model, and the relative humidity is also investigated. For regions with coincident overcast marine stratocumulus, high aerosol loading and high relative humidity, and an external mixture of soot and sulphate aerosol, absolute values of the bias in forcing due to sulphates could reach as much as 1.5 W m-2 for a solar zenith angle of 60°, this being around 15% of the total forcing. Copyright 2000 by the American Geophysical Union."
"56611366900;7005862399;","Spectral dispersion of cloud droplet size distributions and the parameterization of cloud droplet effective radius",2000,"10.1029/1999GL011011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034352796&doi=10.1029%2f1999GL011011&partnerID=40&md5=b95596a7c0c541443449d959a2884cf8","Parameterization of effective radius (r(e)) as proportional to the cube root of the ratio of cloud liquid water content (L) to droplet concentration (N), i.e., r(e)= α(L/N)(1/3), is becoming widely accepted. The principal distinction between different parameterization schemes lies in the specification of the prefactor α. This work focuses on the dependence of α on the spectral dispersion of the cloud droplet size distribution. Relationships by Pontikis and Hicks [1992] and by Liu and Hallet [1997] that account for the dependence of α on the spectral dispersion are compared to each other and to cloud microphysical data collected during two recent field studies. The expression of Liu and Hallet describes the spectral dependence of α (or r(e)) more accurately than the Pontikis and Hicks relation over the observed range of spectral dispersions. The comparison shows that the different treatments of α as a function of spectral dispersion alone can result in substantial differences in r(e) estimated from different parameterization schemes, suggesting that accurately representing r(e) in climate models requires predicting α in addition to L and N."
"7007093785;55910010100;7102490158;","Abrupt changes in meteorological conditions observed at an inland Antarctic station in association with wintertime blocking",2000,"10.1029/1999GL011039","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034352798&doi=10.1029%2f1999GL011039&partnerID=40&md5=90df9b8eaaab936181f27e91153c4291","Time evolution of a prominent wintertime blocking event over East Antarctica and the associated drastic changes in weather conditions observed at an inland station are documented. A strong blocking ridge was formed at the leading edge of a quasi-stationary Rossby wavetrain where a wave activity flux emanating from the subtropics was convergent. The ridge pumped up heat and moisture from lower latitudes into inland Antarctica with a strong poleward flow along its upstream flank. The station was situated under this flow just for two days, during which the normal condition with cold and clear weather was markedly disturbed. The flow climbing up the continental slope led to cloud formation above the inland station. Enhanced downward longwave radiation from the clouds and enhanced vertical mixing associated with the record-setting wind speeds resulted in a sudden, drastic increase in surface air temperature and the breakdown of the developed surface inversion layer."
"56049492900;7410187941;","Using a synoptic climatological approach to understand climate-viticulture relationships",2000,"10.1002/1097-0088(20000630)20:8<813::AID-JOC495>3.0.CO;2-W","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033905871&doi=10.1002%2f1097-0088%2820000630%2920%3a8%3c813%3a%3aAID-JOC495%3e3.0.CO%3b2-W&partnerID=40&md5=cfd7b8cb7bda90965493c44072c4342e","Regional circulation and local air mass synoptic climatologies are developed for Bordeaux, France, to examine the relationship between climate and viticulture. Using a variation of the temporal synoptic index, days with similar weather (both throughout Western Europe and at Bordeaux) are grouped together. The annual relative frequencies of these groups are used as independent variables to investigate climate-viticulture relationships for the region. The viticulture data are divided annualy into stages based on the region-wide mean phenology of the grapevines. Synoptic climate-phenology models are then developed using multiple linear regression analysis. A high degree of spatial and temporal cohesiveness is found between the regional and the local synoptic climatologies. Circulation patterns identified in the regional circulation analyses are linked in a consistent fashion with corresponding thermal, moisture, wind and cloud cover conditions at the Bordeaux site. A small number of synoptic clusters greatly affect viticultural potential throughout the year. In general, vintage quality and production are reduced by (i) increased frequencies of cold- and moisture-producing events that delay the plant's physiology, and (ii) increases in frontal incursions and the associated winds and rain that affect flowering and the setting of berries. Conversely, the relative occurrence of warm, stable events during maturation lead to full ripeness and higher vintage quality. Copyright (C) 2000 Royal Meteorological Society."
"6603809220;","On the ""tuning"" of autoconversion parameterizations in climate models",2000,"10.1029/2000JD900129","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033784910&doi=10.1029%2f2000JD900129&partnerID=40&md5=5b6de49fbc3d5744fdf46816775a9a6a","Autoconversion is a highly nonlinear process, which is usually evaluated in global climate models (GCMs) from the mean in-cloud value of the liquid-water mixing ratio q′l. This biases the calculated auto conversion rate, and may explain why it usually seems to be necessary to reduce the autoconversion threshold to an unrealistically low value to obtain a realistic simulation in a GCM. Two versions of a threshold-dependent autoconversion parameterization are compared in the CSIRO GCM. In the standard (""OLD"") treatment, autoconversion occurs in a grid box whenever the mean in-cloud q′l exceeds the threshold qcrit, which is derived from a prescribed threshold cloud-droplet radius rcrit. In the modified (""NEW"") version, the assumed subgrid moisture distribution from the model's condensation scheme is applied in each grid box to determine the fraction of the cloudy area in which q′l &gt; qcrit, and autoconversion occurs in this fraction only. Simulations are performed using both treatments, for present-day and preindustrial distributions of cloud-droplet concentration, and using different values for rcrit. Changing from the OLD to the NEW treatment means that rcrit can be increased from 7.5 μm to a more realistic 9.3 μm, while maintaining the global-mean liquid-water path at about the same value. Simulations for preindustrial and present-day conditions are compared, to see whether the change of scheme alters the modeled cloud-lifetime effect. It is found that the NEW scheme with rcrit = 9.3 μm gives a 0.5 W m-2 (62%) stronger cloud-lifetime effect than the OLD scheme with rcrit = 7.5 μm."
"6507229952;7403872687;7005052907;6602886081;","Estimating cloud top height and spatial displacement from scan-synchronous GOES images using simplified IR-based stereoscopic analysis",2000,"10.1029/2000JD900064","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785032&doi=10.1029%2f2000JD900064&partnerID=40&md5=044929d78d0c0e34953df4d131b43a9b","An efficient method for estimating cloud top heights and correcting cloud image spatial displacements was developed. The method applies stereoscopic analysis to a pair of scan-synchronous infrared cloud images received from two GOES satellites using a piecewise linear approximation of the relationship between height and infrared brightness temperature of top of the cloud element. The algorithm solves for cloud top heights and subsequently calculates the spatial displacements of cloud images. Optimal parameterization of the piecewise linear approximation is achieved using the shuffled complex evolution (SCE) algorithm. Because the proposed method simplifies the stereoscopic analysis, it allows for an easy implementation of stereoscopic technique on desktop computers. When compared to the standard isotherm matching approaches, the proposed method yielded higher correlation between GOES 8 and GOES 9 scan- simultaneous images after the parallax adjustment. The validity of the linear approximation was tested against temperature profiles obtained from the multiple ground sounding measurements from the Tropical Rainfall Measuring Mission/Texas and Florida Underflights (TRMM/TEFLUN) experiments. The results of this comparison demonstrated good fit, particularly within the troposphere, between the optimized relationship and atmospheric sounding measurements. The data produced by this method, including cloud top temperatures and heights, atmospheric temperature profiles for cloudy sky areas, and spatial displacement-adjusted cloud images, can be useful for weather/climate and atmospheric studies. In particular, the displacement-adjusted cloud images can be critical to develop high-resolution satellite rainfall estimates, which are urgently needed by mesoscale atmospheric modeling and studies, severe weather monitoring, and heavy precipitation and flash flood forecasting. Limitations of the proposed method are also identified and discussed. Copyright 2000 by the American Geophysical Union."
"7202330299;7103313899;55532002300;35422648700;7201630549;","No evidence for solar absorption anomaly by marine water clouds through collocated aircraft radiation measurements",2000,"10.1029/2000JD900062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785170&doi=10.1029%2f2000JD900062&partnerID=40&md5=99221e901d3ca3316bcae59b26d9ecc6","No observational evidence was found for the so-called anomalous solar absorption by maritime water clouds through collocated aircraft measurements taken during the Japanese Cloud-Climate Study (JACCS) program. The aircraft experiment has been carried out by using two aircraft equipped with various instruments for wintertime stratocumulus clouds over an area centered at (29° N, 129° E) in the East China Sea. Here we have carefully analyzed solar absorption by the water stratocumulus clouds observed on February 2, 1998. The visible-band net fluxes measured above and below the cloud layer were almost the same within measurement accuracy; this means no substantial absorption in the visible spectral region. On the other hand, there were significant differences as much as 50-80 W m-2 between the near-infrared-band net fluxes measured above and below the cloud layer; this difference corresponds to absorptance of 6-10% of the total-band solar irradiance above the cloud layer. Without cloud particles, water vapor absorption was estimated to be about 4% of the total-band irradiance for the layer. Distributions along the flight legs of the measured visible-band and near-infrared-band absorptance were in phase in their positions with zero mean visible-band absorptance. The measured radiation budget averaged over long distances along the flight legs for the inhomogeneous cloud layers agreed well with theoretical counterparts calculated for plane-parallel, homogeneous cloud models based on the observed microphysical parameters. Copyright 2000 by the American Geophysical Union."
"8891521600;7402727711;7006147398;57198579670;","Outgoing longwave radiation and cloud radiative forcing of the Tibetan Plateau",2000,"10.1029/2000JD900201","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785630&doi=10.1029%2f2000JD900201&partnerID=40&md5=c2b1ebb54d01d95146c3c3cf93fa8c0a","In order to study the energy balance and the cloud radiative forcing (CRF) of the Tibetan Plateau in detail, 2 years of GMS5 satellite data are employed to analyze the monthly mean outgoing longwave radiation (OLR) and CRF. It should be noted that the temporal resolution of GMS5 data is 1 hour, so the data can be used to study the diurnal variations of OLR. First, a method is presented to retrieve the OLR from split-window channels (10.5-11.5 and 11.5-12.5 μm) and the water vapor channel (6.5-7.0 μm) of GMS5. The method applies the discrete ordinates radiative transfer (DISORT) model together with the radiosonde profiles of the Tibetan Plateau to simulate radiances and fluxes of the three channels. A regression relationship is then developed to calculate the OLR from the observations of the three channels. Since the Tibetan Plateau is located nearly out of the effective observational range of the GMS5 satellite, the regression results of GMS5's split-window channels and water vapor channel are corrected by using simultaneously retrieved results from TIROS Operational Vertical Sounder (TOVS). The correlation coefficient of GMS5 and TOVS results is 0.8510, which is large enough for 1% significant level. The OLR distributions arc calculated for the Tibetan Plateau using 2 years of GMS5 data and the regression and correction methods. The average of the OLR images for the same month and same time gives the monthly mean OLR distribution for each hour. The 24-hour OLR distributions of the same month are then averaged to yield the monthly mean OLR distribution for that month. Then our monthly mean OLR distributions are compared with the Clouds and the Earth's Radiant Energy System (CERES) results, and they are generally in good agreement with differences of <10% for January and 5% for July. Analyzing the monthly mean OLR distributions for different seasons, we find that during the winter season the OLR distribution exhibits low values over the Tibetan Plateau but high values for areas off the Tibetan Plateau. During the summer season the OLR of the southern part is smaller than that of the northern part. Studying the monthly mean diurnal variations of OLR, we find that the diurnal variations of OLR are affected by diurnal cycles of cloud quantity and surface temperature. The relief of the Tibetan Plateau is very high, and the radiative heating is intense after sunrise. The OLR is greatly influenced by the surface and reaches a maximum value soon after sunrise, but the time the minimum OLR emerges varies. After the OLR distributions of the Tibetan Plateau are obtained, the role of clouds in the climate system is also studied. In order to calculate the CRF the International Satellite Cloud Climatology Project (ISCCP) cloud detection algorithm is used to detect the clear pixels for each image. The clear-sky components of OLR and albedo for different months and hours are then derived and averaged over a month to obtain the monthly mean clear-sky OLR and albedo for each hour. Finally, data are averaged over 24 hours to give the monthly mean shortwave CRF (SWCRF), longwave CRF (LWCRF), and CRF. The results show that the CRF over the Tibetan Plateau is negative most of the time. This means the CRF is dominated by cooling effects, and the distribution pattern is mainly determined by the SWCRF component. While the CRFs to the south and the north of the Tibetan Plateau are different, there are obvious annual variations with heating effects in the summer-autumn season and cooling effects in the winter-spring season. Copyright 2000 by the American Geophysical Union."
"7006518289;56520921400;7003684963;7005513582;7005591860;6701508272;","Response of the NCAR climate system model to increased CO2 and the role of physical processes",2000,"10.1175/1520-0442(2000)013<1879:ROTNCS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034210146&doi=10.1175%2f1520-0442%282000%29013%3c1879%3aROTNCS%3e2.0.CO%3b2&partnerID=40&md5=91e8bab86bd89ee7b0b36c30f4ff53e4","The global warming resulting from increased CO2 is addressed in the context of two regional processes that contribute to climate change in coupled climate models, the 'El Nino-like' response (slackening of the equatorial Pacific SST gradient) and sea-ice response at high latitudes. The National Center for Atmospheric Research (NCAR) Climate System Model (CSM) response is compared with results from a coupled model that produces comparatively greater global warming, the NCAR U.S. Department of Energy (DOE) global coupled model. In an experiment where atmospheric CO2 is increased 1% yr-1 compound, globally averaged surface air temperature increase near the time of CO2 doubling for the CSM is 1.43°C (3.50°C for the DOE model). Analysis of a simple coupled model shows the CSM equilibrium sensitivity to doubled CO2 is comparable to that from the slab ocean version (about 2.1°C). One process that contributes to global warming (estimated to be about 5% in one slab ocean model), as well as to significant Pacific region climate effects, is the El Nino-like response. It is a notable feature in the DOE model and some other global coupled models but does not occur in the CSM. The authors show that cloud responses are a major determining factor. With increased CO2, there are negative net cloud-forcing differences in the western equatorial Pacific in the CSM and DOE models, but large positive differences in the DOE model and negative differences in the CSM in the eastern equatorial Pacific. This produces asymmetric cloud radiative forcing contributing to an El Nino-like response in the DOE model and not in the CSM. To remove the amplifying effects of ocean dynamics and to identify possible parameter-dependent processes that could contribute to such cloud forcing changes, the authors analyze slab ocean versions of the coupled models in comparison with a slab ocean configuration of the atmospheric model in the CSM [Community Climate Model Version 3 (CCM3)] that includes prognostic cloud liquid water. The latter shows a change in sign (from negative to positive) of the net cloud forcing in the eastern equatorial Pacific with doubled CO2, similar to the DOE model, in comparison with the CCM3 version with diagnostic cloud liquid water. Atmospheric Model Intercomparison Project (prescribed SST) experiments show that all three atmospheric models (DOE, CCM3 with diagnostic cloud liquid water, and CCM3 with prognostic cloud liquid water) perform poorly relative to observations in terms of cloud radiative forcing, though CCM3 with prognostic cloud liquid water is slightly superior to the others. Another process that contributes to climate response to increasing CO2 is sea-ice changes, which are estimated to enhance global warming by roughly 20% in the CSM and 37% in the DOE model. Sea-ice retreat with increasing CO2 in the CSM is less than in the DOE model in spite of identical sea-ice formulations. Results from the North Atlantic and Greenland-Iceland-Norwegian (GIN) Sea region show that the surface energy budget response is controlled primarily by surface albedo (related to ice area changes) and cloud changes. However, a more important factor is the poleward ocean heat transport associated with changes in meridional overturning in the GIN Sea. With increased CO2, the transport of warmer water from the south into this region in the DOE model is greater in comparison with that of the CSM. This leads to a larger ice reduction in the DOE model, thus also contributing to the enhanced contribution from ice albedo feedback in the DOE model in comparison with the CSM.The global warming resulting from increased CO2 is addressed in the context of two regional processes that contribute to climate change in coupled climate models, the 'El Nino-like' response (slackening of the equatorial Pacific SST gradient) and sea-ice response at high latitudes. The National Center for Atmospheric Research (NCAR) Climate System Model (CSM) response is compared with results from a coupled model that produces comparatively greater global warming, the NCAR U.S. Department of Energy (DOE) global coupled model. In an experiment where atmospheric CO2 is increased 1% yr-1 compound, globally averaged surface air temperature increase near the time of CO2 doubling for the CSM is 1.43°C (3.50°C for the DOE model). Analysis of a simple coupled model shows the CSM equilibrium sensitivity to doubled CO2 is comparable to that from the slab ocean version (about 2.1°C). One process that contributes to global warming (estimated to be about 5% in one slab ocean model), as well as to significant Pacific region climate effects, is the El Nino-like response. It is a notable feature in the DOE model and some other global coupled models but does not occur in the CSM. The authors show that cloud responses are a major determining factor. With increased CO2, there are negative net cloud-forcing differences in the western equatorial Pacific in the CSM and DOE models, but large positive differences in the DOE model and negative differences in the CSM in the eastern equatorial Pacific. This produces asymmetric cloud radiative forcing contributing to an El Nino-like response in the DOE model and not in the CSM. To remove the amplifying effects of ocean dynamics and to identify possible parameter-dependent processes that could contribute to such cloud forcing changes, the authors analyze slab ocean versions of the coupled models in comparison with a slab ocean configuration of the atmospheric model in the CSM [Community Climate Model Version 3 (CCM3)] that includes prognostic cloud liquid water. The latter shows a change in sign (from negative to positive) of the net cloud forcing in the eastern equatorial Pacific with doubled CO2, similar to the DOE model, in comparison with the CCM3 version with diagnostic cloud liquid water. Atmospheric Model Intercomparison Project (prescribed SST) experiments show that all three atmospheric models (DOE, CCM3 with diagnostic cloud liquid water, and CCM3 with prognostic cloud liquid water) perform poorly relative to observations in terms of cloud radiative forcing, through CCM3 with prognostic cloud liquid water is slightly superior to the others."
"7006865796;23091000900;","Coarse-grid and cloud-resolving simulations of a midlatitude cyclonic cloud system: Implications for the parameterization of layer clouds in GCMs",2000,"10.1175/1520-0442(2000)013<1972:CGACRS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034210596&doi=10.1175%2f1520-0442%282000%29013%3c1972%3aCGACRS%3e2.0.CO%3b2&partnerID=40&md5=3e14729151dee7335e5f99cfadd05632","A winter oceanic cyclonic cloud system was simulated by using the mesoscale compressible community (MC2) model with different combinations of model resolutions and cloud microphysics packages. Results from these simulations are intercompared to examine the effects of the coarse model grid and simplified model physics on the simulated large-scale storm environment. When aggregated to an area approximately equivalent to the size of a grid box in current GCMs, the results from the models differ significantly in the large-scale cloud and moisture profiles. Although the effects of using different stratiform cloud schemes on the coarse-grid results are appreciable, the effects of different model resolution are shown to be greater on the large-scale frontal cloud field. In particular, the coarse-grid models underestimated the cloudiness and atmospheric moisture content in the warm-frontal region. Such differences in the large-scale model storm environment were consequences of the stronger mean cross-front circulation and mesoscale cloud features in the high-resolution simulation. The stronger cross-front circulation was in turn a result of stronger frontogenetic processes over the region and dynamic influences of the mesoscale cloud bands on the parent storm. Because both the frontal zones and the mesoscale cloud bands are unresolved features in current GCMs, these results suggest that the parameterization of their bulk effects on the large scales should be included in the representation of frontal layered clouds in climate models.A winter oceanic cyclonic cloud system was simulated by using the mesoscale compressible community (MC2) model with different combinations of model resolutions and cloud microphysics packages. Results from these simulations are intercompared to examine the effects of the coarse model grid and simplified model physics on the simulated large-scale storm environment. When aggregated to an area approximately equivalent to the size of a grid box in current GCMs, the results from the models differ significantly in the large-scale cloud and moisture profiles. Although the effects of using different stratiform cloud schemes on the coarse-grid results are appreciable, the effects of different model resolution are shown to be greater on the large-scale frontal cloud field. In particular, the coarse-grid models underestimated the cloudiness and atmospheric moisture content in the warm-frontal region. Such differences in the large-scale model storm environment were consequences of the stronger mean cross-front circulation and mesoscale cloud features in the high-resolution simulation. The stronger cross-front circulation was in turn a result of stronger frontogenetic processes over the region and dynamic influences of the mesoscale cloud bands on the parent storm. Because both the frontal zones and the mesoscale cloud bands are unresolved features in current GCMs, these results suggest that the parameterization of their bulk effects on the large scales should be included in the representation of frontal layered clouds in climate models."
"7004442182;57203215073;7401984344;","The relationship of cloud cover to near-surface temperature and humidity: Comparison of GCM simulations with empirical data",2000,"10.1175/1520-0442(2000)013<1858:TROCCT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034210912&doi=10.1175%2f1520-0442%282000%29013%3c1858%3aTROCCT%3e2.0.CO%3b2&partnerID=40&md5=dfdf46fb2c3f3b04212cb45cafab30ad","One of the possible ways to check the adequacy of the physical description of meteorological elements in global climate models (GCMs) is to compare the statistical structure of these elements reproduced by models with empirical data from the world climate observational system. The success in GCM development warranted a further step in this assessment. The description of the meteorological element in the model can be considered adequate if, with a proper reproduction of the mean and variability of this element (as shown by the observational system), the model properly reproduces the internal relationships between this element and other climatic variables (as observed during the past several decades). Therefore, to distinguish more reliable models, the authors suggest first analyzing these relationships, 'the behavior of the climatic system,' using observational data and then testing the GCMs' output against this behavior. In this paper, the authors calculated a set of statistics from synoptic data of the past several decades and compared them with the outputs of seven GCMs participating in the Atmospheric Model Intercomparison Project (AMIP), focusing on cloud cover, one of the major trouble spots for which parameterizations are still not well established, and its interaction with other meteorological fields. Differences between long-term mean values of surface air temperature and atmospheric humidity for average and clear sky or for average and overcast conditions characterize the long-term noncausal associations between these two elements and total cloud cover. Not all the GCMs reproduce these associations properly. For example, there was a general agreement in reproducing mean daily cloud-temperature associations in the cold season among all models tested, but large discrepancies between empirical data and some models are found for summer conditions. A correct reproduction of the diurnal cycle of cloud-temperature associations in the warm season is still a major challenge for two of the GCMs that were tested.One of the possible ways to check the adequacy of the physical description of meteorological elements in global climate models (GCMs) is to compare the statistical structure of these elements reproduced by models with empirical data from the world climate observational system. The success in GCM development warranted a further step in this assessment. The description of the meteorological element in the model can be considered adequate if, with a proper reproduction of the mean and variability of this element (as shown by the observational system), the model properly reproduces the internal relationships between this element and other climatic variables (as observed during the past several decades). Therefore, to distinguish more reliable models, the authors suggest first analyzing these relationships, 'the behavior of the climatic system,' using observational data and then testing the GCMs' output against this behavior. In this paper, the authors calculated a set of statistics from synoptic data of the past several decades and compared them with the outputs of seven GCMs participating in the Atmospheric Model Intercomparison Project (AMIP), focusing on cloud cover, one of the major trouble spots for which parameterizations are still not well established, and its interaction with other meteorological fields. Differences between long-term mean values of surface air temperature and atmospheric humidity for average and clear sky or for average and overcast conditions characterize the long-term noncausal associations between these two elements and total cloud cover. Not all the GCMs reproduce these associations properly. For example, there was a general agreement in reproducing mean daily cloud-temperature associations in the cold season among all models tested, but large discrepancies between empirical data and some models are found for summer conditions. A correct reproduction of the diurnal cycle of cloud-temperature associations in the warm season is still a major challenge for two of the GCMs that were tested."
"57127368100;7407805439;","Monsoon ecosystems control on atmospheric CO2 interannual variability: Inferred from a significant positive correlation between year-to-year changes in land precipitation and atmospheric CO2 growth rate",2000,"10.1029/1999GL006073","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034352885&doi=10.1029%2f1999GL006073&partnerID=40&md5=e0cb9b45785bf4c09fdbca791b41070a","Previously, large interannual variability were observed of atmospheric CO2 mixing ratio at Mauna Loa Observatory, and were found to be positively correlated with the global near-surface air temperature variability, notably over El Nino-Southern Oscillation (ENSO) cycles, and negatively correlated with global precipitation on the decadal time-scale. By contrast, here we report a significant positive correlation between the interannual variability of CO2 growth rate and the year-to-year changes in global land precipitation. The interannual extremes in the rate of CO2 growth coincide with the largest year-to-year changes in precipitation over land, particularly Indian summer monsoon. We suggest that this positive correlation results mainly from changes in terrestrial net ecosystem production (NEP) with incoming solar radiation: an increase of clouds concurrent with precipitation reduces seasonal NEP and causes a positive anomaly in CO2 emission from the terrestrial biosphere. Copyright 2000 by the American Geophysical Union."
"57208638573;","Seasonal climate summary southern hemisphere (winter 1999): A return to near-normal conditions in the tropical Pacific",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001082505&partnerID=40&md5=97f5324931f75ffe1c14c77ef169ea12","Circulation patterns and associated anomalies for the austral winter season 1999 are reviewed, with emphasis given to the tropical Pacific and Australian regions. As a whole, surface ocean and atmospheric indicators of the El Niño - Southern Oscillation displayed near neutral values during the winter of 1999, suggesting the moderate La Niña event whose intensity had peaked during the previous summer season had effectively ended. In the ocean subsurface, however, residual cool anomalies persisted through the season, and showed signs of strengthening and expansion in August, forewarning the reestablishment of Pacific cool conditions which was to occur later in the year. In contrast to the near neutral phase of the El Niño - Southern Oscillation in the Pacific, winter 1999 was far from normal in the Australian region. The season as a whole was very anticyclonic, with seasonal pressure anomalies widely greater than +2 hPa, and approaching +5 hPa near Victoria. The positive pressure departures took the form of an anomalously strong and poleward shifted subtropical ridge, and were reflected in the low-level circulation as east to northeast wind anomalies over Australia. Seasonal rainfall totals and cloud amounts were widely below normal, particularly over southern parts, reflecting the prevalence of high pressure systems and a relative absence of substantial frontal passages. Seasonal mean maximum temperatures were mostly higher than normal with the Australia-wide value a near record, while the seasonal mean minimum temperature anomalies were mixed and of modest amplitude."
"7006417494;7004390586;","A quasi-equilibrium tropical circulation model-formulation",2000,"10.1175/1520-0469(2000)057<1741:AQETCM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034210719&doi=10.1175%2f1520-0469%282000%29057%3c1741%3aAQETCM%3e2.0.CO%3b2&partnerID=40&md5=1ac8588fdecc5f2a763d9e714c2a6341","A class of model for simulation and theory of the tropical atmospheric component of climate variations is introduced. These models are referred to as quasi-equilibrium tropical circulation models, or QTCMs, because they make use of approximations associated with quasi-equilibrium (QE) convective parameterizations. Quasi-equilibrium convective closures tend to constrain the vertical temperature profile in convecting regions. This can be used to generate analytical solutions for the large-scale flow under certain approximations. A tropical atmospheric model of intermediate complexity is constructed by using the analytical solutions as the first basis function in a Galerkin representation of vertical structure. This retains much of the simplicity of the analytical solutions, while retaining full nonlinearity, vertical momentum transport, departures from QE, and a transition between convective and nonconvective zones based on convective available potential energy. The atmospheric model is coupled to a one-layer land surface model with interactive soil moisture and simulates its own tropical climatology. In the QTCM version presented here, the vertical structure of temperature variations is truncated to a single profile associated with deep convection. Though designed to be accurate in and near regions dominated by deep convection, the model simulates the tropical and subtropical climatology reasonably well, and even has a qualitative representation of midlatitude storm tracks. The model is computationally economical, since part of the solution has been carried out analytically, but the main advantage is relative simplicity of analysis under certain conditions. The formulation suggests a slightly different way of looking at the tropical atmosphere than has been traditional in tropical meteorology. While convective scales are unstable, the large-scale motions evolve with a positive effective stratification that takes into account the partial cancellation of adiabatic cooling by diabatic heating. A consistent treatment of the moist static energy budget aids the analysis of radiative and surface heat flux effects. This is particularly important highlights the role of top-of-the-atmosphere fluxes including cloud feedbacks, and it illustrates the usefulness of this approach for analysis of convective regions. Reductions of the model for theoretical work or diagnostics are outlined.A class of model for simulation and theory of the tropical atmospheric component of climate variations is introduced. These models are referred to as quasi-equilibrium tropical circulation models, or QTCMs, because they make use of approximations associated with quasi-equilibrium (QE) convective parameterizations. Quasi-equilibrium convective closures tend to constrain the vertical temperature profile in convecting regions. This can be used to generate analytical solutions for the large-scale flow under certain approximations. A tropical atmospheric model of intermediate complexity is constructed by using the analytical solutions as the first basis function in a Galerkin representation of vertical structure. This retains much of the simplicity of the analytical solutions, while retaining full nonlinearity, vertical momentum transport, departures from QE, and a transition between convective and nonconvective zones based on convective available potential energy. The atmospheric model is coupled to a one-layer land surface model with interactive soil moisture and simulates its own tropical climatology. In the QTCM version presented here, the vertical structure of temperature variations is truncated to a single profile associated with deep convection. Though designed to be accurate in and near regions dominated by deep convection, the model simulates the tropical and subtropical climatology reasonably well, and even has a qualitative representation of midlatitude storm tracks. The model is computationally economical, since part of the solution has been carried out analytically, but the main advantage is relative simplicity of analysis under certain conditions. The formulation suggests a slightly different way of looking at the tropical atmosphere than has been traditional in tropical meteorology. While convective scales are unstable, the large-scale motions evolve with a positive effective stratification that takes into account the partial cancellation of adiabatic cooling by diabatic heating. A consistent treatment of the moist static energy budget aids the analysis of radiative and surface heat flux effects. This is particularly important over land regions where the zero net surface flux links land surface anomalies. The resulting simplification highlights the role of top-of-the-atmosphere fluxes including cloud feedbacks, and it illustrates the usefulness of this approach for analysis of convective regions. Reductions of the model for theoretical work or diagnostics are outlined."
"57203053317;7003931528;7102604282;7801611677;","Indirect effect of sulfate and carbonaceous aerosols: A mechanistic treatment",2000,"10.1029/1999JD901199","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033784623&doi=10.1029%2f1999JD901199&partnerID=40&md5=d6c6949a40c7955b723c5a3c9fc7778d","The indirect effect of anthropogenic aerosols, whereby aerosol particles change cloud optical properties, is the most uncertain component of climate forcing over the past 100 years. Here we use a mechanistic treatment of droplet nucleation and a prognostic treatment of the number of cloud droplets to study the indirect aerosol effect from changes in carbonaceous and sulfate aerosols. Cloud droplet nucleation is parameterized as a function of total aerosol number concentration, updraft velocity, and an activation parameter, which takes into account the mechanism of sulfate aerosol formation. Where previous studies focussed either on sulfate aerosols or carbonaceous aerosols only, here we estimate the combined effect. The combined indirect aerosol effect amounts to -1.1 W m-2 for an internally mixed aerosol and -1.5 W m-2 for an externally mixed aerosol compared to -1.4 W m-2, which we obtained by empirically relating sulfate mass to cloud droplet number. In the case of an internally mixed aerosol, the contribution from increasing carbonaceous and sulfate aerosols is close to being additive as the individual simulations yield an indirect effect of -0.4 W m-2 due to anthropogenic sulfate aerosols and -0.9 W m-2 due to anthropogenic carbonaceous aerosols. The contribution of anthropogenic sulfate to the indirect effect is close to zero if an externally mixed aerosol is assumed, while the contribution of carbonaceous aerosols increases to -1.3 W m-2. The effect of sulfate in the external mixture approach is much smaller than that of carbonaceous aerosols because its burden only increases by a third of that of carbonaceous aerosols and because the mode radius of sulfate is much larger than that of black and organic carbon. Copyright 2000 by the American Geophysical Union."
"7005955015;24080547200;","Is there a cosmic ray signal in recent variations in global cloudiness and cloud radiative forcing?",2000,"10.1029/2000JD900029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033789062&doi=10.1029%2f2000JD900029&partnerID=40&md5=76834a471f51e6e8b782d8b7406e264d","In order to evaluate a recent hypothesis of a coupling between galactic cosmic rays, clouds, and climate we have investigated temporal variations in global cloudiness and radiative fluxes at the top of the atmosphere. For this purpose we have used the best available global data sets, i.e., those of the International Satellite Cloud Climatology Project (ISCCP) and the Earth Radiation Budget Experiment (ERBE), respectively. Both globally and over midlatitude oceans only, we find a decrease in total cloud coverage between 1986 and 1990 of 2%, while between 1990 and 1993 there is a slightly smaller decrease. When the results are related to temporal variations in cosmic ray activity, we do not find support for a coupling between cosmic rays, total cloudiness, and radiative forcing of climate. A possible exception is low marine clouds at midlatitudes, characterized by few cloud condensation nuclei and a large net cooling effect, but no physical mechanism is known which might explain a connection between cosmic rays and low clouds. The net radiative effect of clouds during the period 1985-1989 shows an enhanced cooling effect despite a reduction in both total and low cloud cover. This contradicts the simple relationship between cloud cover and radiation assumed in the cosmic-ray-cloud-climate hypothesis. The interpretation of the results is rendered difficult by the short time series of ISCCP and ERBE data and by uncertainties concerning instrument calibrations and changes of satellites. When a 43-year time series of synoptic observations over sea is related to cosmic rays over the same period, a weak, negative correlation is found. Copyright 2000 by the American Geophysical Union."
"57201124395;6603221134;7005140302;7004494327;7801371382;6701843835;","Cloud processing of continental aerosol particles: Experimental investigations for different drop sizes",2000,"10.1029/1999JD901061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033793908&doi=10.1029%2f1999JD901061&partnerID=40&md5=203e1af6756b5efc88a7ac3b23508252","Atmospheric aerosol particles are activated and grow into drops during the formation of a cloud. Subsequently, they are delivered from the dissipating cloud drops back to the atmosphere. During the cloud lifetime, the drops scavenge water-soluble trace gases, leading to an increase in size and solubility of the particles emerging from the evaporating cloud drops. This processing of aerosol particles by clouds has an influence on the microphysics of the following cloud and its probability to rain as well as on the cooling effect of the direct and indirect aerosol forcing of climate. To measure the cycling history (particle activation and gas scavenging in drops followed by processing of the activated particles followed by emerging processed particles) of continental aerosol particles passing through cloud drops of different sizes, a new method is developed and applied during three field experiments carried out on the Mount Kleiner Feldberg/Ts., Germany, in 1990, 1993, and 1995. The typical droplet spectra of most of the observed stratus clouds is weakly bimodal, with mode 1 at drop sizes between 3 and 5 μm and mode 2 between 5 and 10 μm radius. Cloud drops in this overall size range are subject to growth only by condensation, while coalescence can be neglected. Therefore the observed processing is related solely to gas scavenging and in-cloud chemical reactions. We found that the processing of particles is different for the two modes of the cloud drop size spectrum: Small activated particles mostly grow to the small drops of mode 1, while larger particles can grow further to the larger drops of mode 2. Likewise, the mass of scavenged gas is, on average, lower for the small than for the larger drops. Vice versa, the ratio of scavenged gas to particle mass, the parameter quantifying the particle processing, is, on average, found to be higher in the small drop mode containing the smaller particles. The reason is that the degree of processing is mainly inversely linked to the mass of the activated particles. Therefore the strongest modification of particles takes place in smaller drops and affects mainly the smaller activated particles (rap ≤ 0.1 μm). Their radii can increase by up to a factor of 3 and, consequently, their nucleation as well as radiative properties change significantly. The consequence for the aerosol climate forcing is that the cooling can be, to an unknown extent, intensified with increasing atmospheric amount of watersoluble trace gases such as HNO3, NH3, and SO2, counteracting the warming effect of the greenhouse gases. Copyright 2000 by the American Geophysical Union."
"7004563100;7103119050;35494005000;","A cloud climatology of the Southern Great Plains ARM CART",2000,"10.1175/1520-0442(2000)013<1762:ACCOTS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033939150&doi=10.1175%2f1520-0442%282000%29013%3c1762%3aACCOTS%3e2.0.CO%3b2&partnerID=40&md5=4d84354a905f02f9997533ec928aa40a","Cloud amount statistics from three different sources were processed and compared. Surface observations from a National Centers for Environmental Prediction dataset were used. The data (Edited Cloud Report; ECR) consist of synoptic weather reports that have been edited to facilitate cloud analysis. Two stations near the Southern Great Plains (SGP) Cloud and Radiation Test Bed (CART) in north-central Oklahoma (Oklahoma City, Oklahoma and Wichita, Kansas) were selected. The ECR data span a 10-yr period from December 1981 to November 1991. The International Satellite Cloud Climatology Project (ISCCP) provided cloud amounts over the SGP CART for an 8-yr period (1983-91). Cloud amounts were also obtained from Micro Pulse Lidar (MPL) and Belfort Cellometer (BLC) cloud-base height measurements made at the SGP CART over a 1-yr period. The annual and diurnal cycles of cloud amount as a function of cloud height and type were analyzed. The three datasets closely agree for total cloud amount. Good agreement was found in the ECR and MPL-BLC monthly low cloud amounts. With the exception of summer and midday in other seasons, the ISCCP low cloud amount estimates are generally 5%-10% less than the others. The ECR high cloud amount estimates are typically 10%-15% greater than those obtained from either the ISCCP or MPL-BLC datasets. The observed diurnal variations of altocumulus support the authors' model results of radiatively induced circulations.Cloud amount statistics from three different sources were processed and compared. Surface observations from a National Centers for Environmental Prediction dataset were used. The data (Edited Cloud Report; ECR) consist of synoptic weather reports that have been edited to facilitate cloud analysis. Two stations near the Southern Great Plains (SGP) Cloud and Radiation Test Bed (CART) in north-central Oklahoma (Oklahoma City, Oklahoma and Wichita, Kansas) were selected. The ECR data span a 10-yr period from December 1981 to November 1991. The International Satellite Cloud Climatology Project (ISCCP) provided cloud amounts over the SGP CART for an 8-yr period (1983-91). Cloud amounts were also obtained from Micro Pulse Lidar (MPL) and Belfort Ceilometer (BLC) cloud-base height measurements made at the SGP CART over a 1-yr period. The annual and diurnal cycles of cloud amount as a function of cloud height and type were analyzed. The three datasets closely agree for total cloud amount. Good agreement was found in the ECR and MPL-BLC monthly low cloud amounts. With the exception of summer and midday in other seasons, the ISCCP low cloud amount estimates are generally 5%-10% less than the others. The ECR high cloud amount estimates are typically 10%-15% greater than those obtained from either the ISCCP or MPL-BLC datasets. The observed diurnal variations of altocumulus support the authors' model results of radiatively induced circulations."
"6701670597;","Convective inhibition, subgrid-scale triggering energy, and stratiform instability in a toy tropical wave model",2000,"10.1175/1520-0469(2000)057<1515:CISSTE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034193907&doi=10.1175%2f1520-0469%282000%29057%3c1515%3aCISSTE%3e2.0.CO%3b2&partnerID=40&md5=0f569080b7b956f9c4b088477f2fac63","A toy model of large-scale deep convection variations is constructed around a radiative-convective equilibrium climate, with an observed mean sounding as its thermodynamic basic state. Vertical structure is truncated at two modes, excited by convective (one-signed) and stratiform (two-signed) heating processes in tropical deep convection. Separate treatments of deep and shallow convection are justified by observations that deep convection is more variable. Deep convection intensity is assumed to be modulated by convective available potential energy (CAPE), while occurrence frequency is modulated by the ratio of convective inhibition (CIN) to 'triggering energy' K, a scalar representing the intensity of subgrid-scale fluctuations. Deep convective downdrafts cool and dry the boundary layer but also increase K. Variations of K make the relationship between convection and thermodynamic variables (CAPE, CIN, θ(e)) nonunique and amplify the deep convective response to temperature waves of small (~1°C) amplitude. For a parameter set in which CAPE variations control convection, moist convective damping destroys all variability. When CIN/K variations have dominant importance (the 'inhibition-controlled' regime), a mechanism termed 'stratiform instability' generates large-scale waves. This mechanism involves lower-tropospheric cooling by stratiform precipitation, which preferentially occurs where the already cool lower troposphere favors deep convection, via smaller CIN. Stratiform instability has two subregimes, based on the relative importance of the two opposite effects of downdrafts: When boundary layer θ(e) reduction (a local negative feedback) is stronger, small-scale waves with frequency based on the boundary layer recovery time are preferred. When the K-generation effect (positive feedback) is stronger, very large scales (low wavenumbers of the domain) develop. A mixture of these scales occurs for parameter choices based on observations. Model waves resemble observed waves, with a phase speed ~20 m s-1 (near the dry wave speed of the second internal mode), and a 'cold boomerang' vertical temperature structure. Although K exhibits 'quasi-equilibrium' with other convection variables (correlations &gt; 0.99), replacing the prognostic K equation with diagnostic equations based on these relationships can put the model into wildly different regimes, if small time lags indicative of causality are distorted. The response of model convection to climatological spatial anomalies of θ(e) (proxy for SST) and K (proxy for orographic and coastal triggering) is considered. Higher SST tends broadly to favor convection under either CAPE-controlled or inhibition-controlled regimes, but there are dynamical embellishments in the inhibition-controlled regime. The Kelvin wave seems to be the preferred structure when the model is run on a uniform equatorial β plane.A toy model of large-scale deep convection variations is constructed around a radiative-convective equilibrium climate. This article reviews a general body of ideas and observations intended to modify and justify the model."
"7006600876;57217462917;26031912400;","ENSO simulated by intermediate coupled models and evaluated with observations over 1970-98. Part I: Role of the off-equatorial variability",2000,"10.1175/1520-0442(2000)013<1605:ESBICM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033922819&doi=10.1175%2f1520-0442%282000%29013%3c1605%3aESBICM%3e2.0.CO%3b2&partnerID=40&md5=14b60e80c70b2cb09618bf2a732edb24","ENSO simulations are investigated in 30-yr integrations of various intermediate coupled models and compared with observed SST, wind, and thermocline depth anomalies over the tropical Pacific. The Cane and Zebiak model simulates warm events with a period close to the observations, but with westerlies that are located 30°east of them and thermocline anomalies in the western Pacific that are much shallower. Between two warm events, the model simulates a series of three weak and short cold SST peaks and hardly ever simulates easterlies. The SST in the eastern equatorial Pacific is not sensitive to thermocline depth anomalies, but to the anomalous downwelling of surface currents induced by Ekman shear. The model simulates a pair of very strong cyclonic wind stress curl anomalies on both sides of the equator in the eastern off-equatorial domain between 7°and 15°lat. These are necessary to maintain the oscillatory regime-so are the ocean meridional Rossby modes higher than 5. The thermocline zonal slopes required to balance the off-equatorial curl anomalies are about three times steeper than the ones required to balance the zonal stress along the equator. Thus the off-equator exerts an excess of zonal pressure, which by continuity affects the equatorial ocean and plays a crucial role in reversing and triggering the growing events. Six months after the warm peaks, the whole ocean between 15°S and 15°N is significantly upwelled. The equatorial oceanic heat content is recharged from the south prior to a warm event. Contrary to simulations when the model is driven by observed wind anomalies, increasing the friction in the baroclinic ocean does not decrease the off-equatorial variability but significantly alters the low-frequency oscillations that are no longer ENSO-like. Introducing the parameterization of subsurface temperature derived from hydrographic profiles in the ocean component does not allow the coupled model to recover cold events as in a forced context. Introducing the parameterization of convection derived from high-cloud temperature measurements is the most effective improvement, but results still poorly agree with observations and are in contrast with the simulations driven by observed SST, biased toward westerlies in the central Pacific, upwelled thermocline in the west, and warm SST in the east. Thus modifying the ocean component only or the atmosphere only does not have the same impact on simulations as in a forced context. The coupling allows new mechanisms to grow and govern the model behavior. One of them is the slow meridional oceanic mass adjustment in quasi-Sverdrup balance with the winds.ENSO simulations are investigated in 30-yr integrations of various intermediate coupled models and compared with observed SST, wind, and thermocline depth anomalies over the tropical Pacific. The Cane and Zebiak model simulates warm events with a period close to the observations, but with westerlies that are located 30° east of them and thermocline anomalies in the western Pacific that are much shallower. Between two warm events, the model simulates a series of three weak and short cold SST peaks and hardly ever simulates easterlies. The SST in the eastern equatorial Pacific is not sensitive to thermocline depth anomalies, but to the anomalous downwelling of surface currents induced by Ekman shear. The model simulates a pair of very strong cyclonic wind stress curl anomalies on both sides of the equator in the eastern off-equatorial domain between 7° and 15° lat. These are necessary to maintain the oscillatory regime - so are the ocean meridional Rossby modes higher than 5. The thermocline zonal slopes required to balance the off-equatorial curl anomalies are about three times steeper than the ones required to balance the zonal stress along the equator. Thus the off-equator exerts an excess of zonal pressure, which by continuity affects the equatorial ocean and plays a crucial role in reversing and triggering the growing events. Six months after the warm peaks, the whole ocean between 15°S and 15°N is significantly upwelled. The equatorial oceanic heat content is recharged from the south prior to a warm event. Contrary to simulations when the model is driven by observed wind anomalies, increasing the friction in the baroclinic ocean does not decrease the off-equatorial variability but significantly alters the low-frequency oscillations that are no longer ENSO-like. Introducing the parameterization of subsurface temperature derived from hydrographic profiles in the ocean component does not allow the coupled model to recover cold events as in a forced context. Introducing the parameterization of convection derived from high-cloud temperature measurements is the most effective improvement, but results still poorly agree with observations and are in contrast with the simulations driven by observed SST, biased toward westerlies in the central Pacific, upwelled thermocline in the west, and warm SST in the east. Thus modifying the ocean component only or the atmosphere only does not have the same impact on simulations as in a forced context. The coupling allows new mechanisms to grow and govern the model behavior. One of them is the slow meridional oceanic mass adjustment in quasi-Sverdrup balance with the winds."
"7004299063;","Volcanic eruptions and climate",2000,"10.1029/1998RG000054","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034463336&doi=10.1029%2f1998RG000054&partnerID=40&md5=b28f9616107e9a4cd6c36af6b87d6a3e","Volcanic eruptions are an important natural cause of climate change on many timescales. A new capability to predict the climatic response to a large tropical eruption for the succeeding 2 years will prove valuable to society. In addition, to detect and attribute anthropogenic influences on climate, including effects of greenhouse gases, aerosols, and ozone-depleting chemicals, it is crucial to quantify the natural fluctuations so as to separate them from anthropogenic fluctuations in the climate record. Studying the responses of climate to volcanic eruptions also helps us to better understand important radiative and dynamical processes that respond in the climate system to both natural and anthropogenic forcings. Furthermore, modeling the effects of volcanic eruptions helps us to improve climate models that are needed to study anthropogenic effects. Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about 1 year. Large ash particles fall out much quicker. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. By scattering some solar radiation back to space, the aerosols cool the surface, but by absorbing both solar and terrestrial radiation, the aerosol layer heats the stratosphere. For a tropical eruption this heating is larger in the tropics than in the high latitudes, producing an enhanced pole-to-equator temperature gradient, especially in winter. In the Northern Hemisphere winter this enhanced gradient produces a stronger polar vortex, and this stronger jet stream produces a characteristic stationary wave pattern of tropospheric circulation, resulting in winter warming of Northern Hemisphere continents. This indirect advective effect on temperature is stronger than the radiative cooling effect that dominates at lower latitudes and in the summer. The volcanic aerosols also serve as surfaces for heterogeneous chemical reactions that destroy stratospheric ozone, which lowers ultraviolet absorption and reduces the radiative heating in the lower stratosphere, but the net effect is still heating. Because this chemical effect depends on the presence of anthropogenic chlorine, it has only become important in recent decades. For a few days after an eruption the amplitude of the diurnal cycle of surface air temperature is reduced under the cloud. On a much longer timescale, volcanic effects played a large role in interdecadal climate change of the Little Ice Age. There is no perfect index of past volcanism, but more ice cores from Greenland and Antarctica will improve the record. There is no evidence that volcanic eruptions produce El Niño events, but the climatic effects of El Nino and volcanic eruptions must be separated to understand the climatic response to each."
"56033135100;","South American palaeoclimate model simulations: How reliable are the models?",2000,"10.1002/1099-1417(200005)15:4<357::AID-JQS547>3.0.CO;2-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033937414&doi=10.1002%2f1099-1417%28200005%2915%3a4%3c357%3a%3aAID-JQS547%3e3.0.CO%3b2-8&partnerID=40&md5=fe63bf7753bf136abdb23b57be31a82e","Modelling climate change over South America represents a special challenge for computer climate models. The coarse resolution of most general circulation models (GCM) means that the high but narrow relief of the Andes is poorly represented. In addition, changes in the tropical lowlands will be strongly dependent on the ability of the models to accurately simulate convection, cloud cover and land surface processes. Both marine and terrestrial data also will be relatively sparse compared with northern latitudes. This paper examines the modelling uncertainties by discussing results from the Palaeoclimate Model Intercomparison Project (PMIP), which simulated the mid-Holocene (6 kyr BP) and the Last Glacial Maximum (LGM, 21 kyr BP). The PMIP mid-Holocene experiments show a reasonable amount of agreement, especially for surface air temperature changes. The PMIP LGM simulations show a greater degree of scatter, which is partly associated with uncertainties in the treatment of the ocean surface. This suggests that uncertainties in the boundary conditions can be as important or more important than uncertainties due to the internal physics within the GCMs. In addition, we consider the results from a new set of simulations for 15 kyr BP, 12 kyr BP and 9 kyr BP, using the climate model of the UK Universities Global Atmospheric Modelling Programme (UGAMP). We compare these results with previous simulations by COHMAP. The higher resolution of the UGAMP model allows us to examine mid-latitude storm-track changes. The changes in the storm track are largest upstream of South America and reach their largest at around 15 kyr. The model also predicts a positive snow mass balance in the Southern Andes up until 12 kyr BP. The associated changes in mid-latitude temperatures and precipitation over South America, however, are generally small and are broadly in agreement with previous studies. All of these results suggest that the basic elements of the GCM predictions of climate change are relatively robust, and the most important uncertainties probably arise from lack of detailed knowledge of the required boundary conditions. The next generation of climate models will alleviate many of these problems. Copyright (C) 2000 John Wiley and Sons, Ltd."
"7402744444;7103054576;","Validation and Uncertainty Analysis of Satellite Rainfall Algorithms",2000,"10.1111/0033-0124.00222","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047699432&doi=10.1111%2f0033-0124.00222&partnerID=40&md5=6796f8a2ec45154270a350826ebc5df3","Satellites, while offering excellent spatial coverage, determine precipitation indirectly, using algorithms that transform satellite-sensed radiance (either emitted or scattered) from clouds or raindrops into precipitation. A large uncertainty is associated with satellite precipitation estimates, stemming from unknown variation in space and time of the physical and statistical relationships between precipitation and satellite-sensed radiance. To mitigate this, satellite algorithms must be calibrated and verified using surface precipitation sampled from different climate regimes and seasons. Recently developed statistical techniques have been used effectively to reduce spatial sampling error associated with sparsely distributed raingages and thereby improve our understanding of satellite algorithm quality. This paper provides an example of satellite precipitation validation, including a description of the types of satellite data used to estimate precipitation, as well as the results from a major project (the Global Precipitation Climatology Project [GPCP]), to estimate global precipitation through a combination of satellite and raingage products. In addition, a recently developed procedure to investigate spatial averaging, scaling, and uncertainty analysis will be used to examine the GPCP product. Specifically, uncertainty analysis applied to comparisons between satellite monthly rainfall estimates and rainfall estimates constructed from Pacific atoll-sited raingauge sites will be discussed. © 2000 Taylor & Francis Group, LLC. All rights reserved."
"7405541413;7201381456;36757271900;","Interaction between the summer monsoons in East Asia and the South China Sea: Intraseasonal monsoon modes",2000,"10.1175/1520-0469(2000)057<1373:IBTSMI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034042456&doi=10.1175%2f1520-0469%282000%29057%3c1373%3aIBTSMI%3e2.0.CO%3b2&partnerID=40&md5=28886765be3274f6ce32aa6febe0a157","The summer monsoons in East and Southeast Asia are characterized, respectively, by the Mei-yu (in eastern China)-Baiu (in Japan) front (MBF) and by the monsoon trough stretching from northern Indochina to the Philippine Sea. These two major monsoon elements are separated by the North Pacific anticyclone. As indicated by the 850-mb zonal wind and cumulus convection over some key areas, a distinct opposite-phase intraseasonal variation exists between the two monsoon elements. Two approaches are adopted to explore the cause of this opposite-phase variation (which reflects the coupling between the two monsoon components): 1) the correlation coefficient patterns between the 850-mb zonal-wind monsoon index and the 850-mb streamfunction field and 2) the composite 850-mb streamline charts and the 120°E zonal-wind cross sections. It is shown that the opposite-phase variation between the two monsoon elements is caused by the anomalous circulation associated with the northward-migrating 30-60 day monsoon trough/ridge from the equator to 20°N and with the westward-propagating 12-24 day monsoon low-high along the latitude of ~15°-20°N. Results obtained in this study are used to address two often discussed phenomena of the East Asian monsoon: 1) the rapid northward shift of the MBF across the Yangtze River basin during the Mei-yu onset is related to the north-south meridional oscillation of the MBF, and 2) the three longitudinally oriented location zones of extremely heavy rain events in eastern China are formed by the alternation of deep cumulus convection zones associated with the intraseasonal monsoon vortices (centered in the northern part of the South China Sea) between extreme monsoon conditions.The summer monsoons in East and Southeast Asia are characterized, respectively, by the Mei-yu (in eastern China)-Baiu (in Japan) front (MBF) and by the monsoon trough stretching from northern Indochina to the Philippine Sea. These two major monsoon elements are separated by the North Pacific anticyclone. As indicated by the 850-mb zonal wind and cumulus convection over some key areas, a distinct opposite-phase intraseasonal variation exists between the two monsoon elements. Two approaches are adopted to explore the cause of this opposite-phase variation (which reflects the coupling between the two monsoon components): 1) the correlation coefficient patterns between the 850-mb zonal-wind monsoon index and the 850-mb streamfunction field and 2) the composite 850-mb streamline charts and the 120°E zonal-wind cross sections. It is shown that the opposite-phase variation between the two monsoon elements is caused by the anomalous circulation associated with the northward-migrating 30-60-day monsoon trough/ridge from the equator to 20°N and with the westward-propagating 12-24-day monsoon low-high along the latitude of approximately 15°-20°N. Results obtained in this study are used to address two often discussed phenomena of the East Asian monsoon: 1) the rapid northward shift of the MBF across the Yangtze River basin during the Mei-yu onset is related to the north-south meridional oscillation of the MBF, and 2) the three longitudinally oriented location zones of extremely heavy rain events in eastern China are formed by the alternation of deep cumulus convection zones associated with the intraseasonal monsoon vortices (centered in the northern part of the South China Sea) between extreme monsoon conditions."
"7005213997;","Estimating the effect of clouds on the arctic surface energy budget",2000,"10.1029/2000JD900043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17544362745&doi=10.1029%2f2000JD900043&partnerID=40&md5=ddbfe91df1ea789767c6fd145db9127f","The relationship between cloudiness and sea ice thickness over the Arctic Ocean is examined using an idealized equilibrium energy budget model and a single-column model (SCM) forced by incoming solar radiation, atmospheric poleward energy flux, oceanic heat flux, and sea ice divergence. The sensitivity of ice thickness to cloud perturbations in the SCM is qualitatively different from previous modeling studies, which did not allow the atmospheric temperature profile to respond to perturbations in cloudiness. It is shown that this restriction implicitly changes the poleward energy flux in model experiments and obscures the intrinsic effect of clouds on the arctic climate. In the present model, equilibrium ice thickness has a strong negative correlation with cloud radiative forcing at the top of the atmosphere and no correlation with cloud radiative forcing at the surface. The results demonstrate how local processes, such as the surface albedo feedback, affect the sensitivity of ice thickness to cloud perturbations and reduce its predictability. Exploratory model experiments suggest that interactions between the Arctic and the lower latitudes (via the poleward energy flux) could strongly influence the dependence of ice thickness on cloudiness. The impact of these interactions in the model was predicted qualitatively by considering how the radiative effect of clouds, is partitioned between the atmosphere and the surface. The results demonstrate the importance of using cloud radiative forcing at both the surface and the top of the atmosphere when estimating the climatic effect of perturbation in cloudiness. Copyright 2000 by the American Geophysical Union."
"6603613067;7003371432;7003942283;7006084942;7203001286;27267529400;6701553081;57203053317;26643510900;","Sensitivity of sulphate aerosol size distributions and CCN concentrations over North America to SOx emissions and H2O2 concentrations",2000,"10.1029/2000JD900027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785085&doi=10.1029%2f2000JD900027&partnerID=40&md5=b84a07067b6b278e84d785e4b21b80cb","To assess the influence of aerosols on climate, the Northern Aerosol Regional Climate Model (NARCM) is currently being developed. NARCM includes size-segregated aerosols as prognostic and interactive constituents. In this paper, the model is being applied to sulphate aerosol over North America during time periods in July and December 1994. The results give evidence for considerable regional and seasonal variations in sulphate aerosol size distributions over North America. Comparisons of the results with different observations yield a reasonably good agreement in terms of meteorological and physicochemical parameters. Some of the differences in sulphate concentrations and wet deposition rates can be attributed to differences in cloud amounts and precipitation between model results and observations. Indirect tests of the simulated aerosol mass mean diameters are also encouraging. Additional simulations for hypothetical decreases in anthropogenic sulphur emissions and increases in hydrogen peroxide (H2O2) background concentrations are performed for the same time periods to study the responses of concentration, size distribution, and wet deposition of sulphate aerosol to these changes. Also, responses of cloud condensation nuclei (CCN) number concentrations are investigated. The simulation results show that sulphate aerosol concentrations respond almost linearly in both time periods to decreases in sulphur emissions but that CCN number concentrations respond nonlinearly due to decreases in sulphate mass mean diameters. Especially for the December period, increases in hydrogen peroxide background concentrations lead to increases in CCN number concentrations at critical diameters larger than about 0.07 μm. These results lead to the hypothesis that increased in-cloud oxidation in convective clouds due to future increases in oxidant concentrations may produce larger CCN which eventually can be easily activated in subsequently forming stratiform clouds. Copyright 2000 by the American Geophysical Union."
"6603928297;7005212820;6507460574;55388694300;","Sampling strategies for the comparison of climate model calculated and satellite observed brightness temperatures",2000,"10.1029/1999JD901182","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033784758&doi=10.1029%2f1999JD901182&partnerID=40&md5=b5e035dfbcf8aba90a0c8a3f9a3720f3","Brightness temperatures derived from polar-orbiting satellites are valuable for the evaluation of global climate models. However, the effect of orbital constraints must be taken into account to ensure valid comparisons. As part of the Atmospheric Model Intercomparison Project II climate model comparisons, this study seeks to evaluate the monthly mean simulated brightness temperature differences of possible model output sampling strategies with respect to the exact satellite sampling and whether they can be practically implemented to provide meaningful comparisons with these satellite observations. We compare various sampling strategies with a proxy satellite data set constructed from model output and actual TIROS operational vertical sounder orbital trajectories, rather than with the observations themselves. To a large extent, this enables isolation of the sampling error from errors caused by deficiencies in the modeled climate processes. Our results suggest that the traditional method of calculating brightness temperatures from monthly mean temperature and moisture profiles yields biases from both nonlinear effects and the removal of the diurnal cycle that may be unacceptable in many applications. However, we also find that a brightness temperature calculation every hour of the simulation provides substantially lower sampling biases provided that there are two or more properly aligned satellites. This is encouraging because it means that for many applications modelers need not accurately mimic actual satellite trajectories in the sampling of their simulations. If only one satellite is available for comparison with simulations, more sophisticated sampling seems necessary. For such circumstances, we introduce a simple procedure that serves as a useful approximation to the rather complex procedure required to sample a model exactly as a polar-orbiting satellite does the Earth. With all sampling methods, removal of biases associated with cloud cover is problematic and deserves further study. Copyright 2000 by the American Geophysical Union."
"7102892446;7202152636;","A study of the effects of sub-grid-scale land use differences on atmospheric stability in prestorm environments",2000,"10.1029/1999JD901121","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033784050&doi=10.1029%2f1999JD901121&partnerID=40&md5=b962a96ee460ac04e21ea75ec3ad0440","The effects of sub-grid-scale land use differences in modifying the stability of prestorm environments has been studied using data from the Department of Energy Cloud and Radiation Testbed (CART) in Kansas and Oklahoma and a mesoscale model. To quantify the atmospheric instability, three indices were used: the lifted index, the modified K index, and convective available potential energy. The spatial variations of these indices were calculated from simulations using spatially varying and spatially uniform surface fluxes as lower boundary conditions. The CART is approximately 105 km2 in area and is characterized by large areas of contrasting vegetation cover and surface sensible and latent heat fluxes. The spatially varying fluxes were calculated with the SiB2 model using data from the CART. Six days, during which isolated thunderstorms developed, were chosen for the study. The results suggest that sub-grid-scale variations in land use differences do not modify the spatial distribution of the stability indices in the southern Great Plains to any significant degree. Predictions of areas of preferred development of deep convection, based on changes in the indices, are not improved by accounting for sub-grid-scale variations in land use. The indices were found to be potentially useful but imperfect indicators of the occurrence of deep convective precipitation at scales smaller than that of the CART. At the model resolution used (grid spacing of 2.08 km) a close correlation was not found between regions of precipitation and regions with enhanced simulated vertical updrafts related to land-use differences, but a detailed study of local triggering has not been carried out. Copyright 2000 by the American Geophysical Union."
"57212856885;7102636922;","Development of an Antarctic regional climate system model. Part II: Station validation and surface energy balance",2000,"10.1175/1520-0442(2000)013<1351:DOAARC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034076424&doi=10.1175%2f1520-0442%282000%29013%3c1351%3aDOAARC%3e2.0.CO%3b2&partnerID=40&md5=0b57c240bf26bf777b1bd0289540fcfa","In this, the second part of the analysis of an Antarctic regional climate system model, the model results and analyses are compared to a series of observational data from automated weather stations at a number of Antarctic stations, radiosonde launches, and surface energy balance climatology. The observational analyses show significant biases in comparison with station data, which is attributable in part to the errors in and low resolution of the elevation dataset. This is a factor in model performance also. Further, a dominant factor in the generation of the model biases is the simulation of atmospheric water vapor and cloud. The known 'cold' bias in the clear-sky longwave radiation scheme is amply compensated for by excessive cloudiness in many cases. The strong vertical moisture transport contributes to the excessive cloud formation. The biases explored in detail in this paper are common to regional and global simulations of the Antarctic region and highlight areas in which model development should be concentrated, particularly in coupled models with greater degrees of freedom.In this, the second part of the analysis of an Antarctic regional climate system model, the model results and analyses are compared to a series of observational data from automated weather stations at a number of Antarctic stations, radiosonde launches, and surface energy balance climatology. The observational analyses show significant biases in comparison with station data, which is attributable in part to the errors in and low resolution of the elevation dataset. This is a factor in model performance also. Further, a dominant factor in the generation of the model biases is the simulation of atmospheric water vapor and cloud. The known 'cold' bias in the clear-sky longwave radiation scheme is amply compensated for by excessive cloudiness in many cases. The strong vertical moisture transport contributes to the excessive cloud formation. The biases explored in detail in this paper are common to regional and global simulations of the Antarctic region and highlight areas in which model development should be concentrated, particularly in coupled models with greater degrees of freedom."
"7005909563;7101867299;7004093651;","A GCM investigation into the nature of baroclinic adjustment",2000,"10.1175/1520-0469(2000)057<1141:AGIITN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034043786&doi=10.1175%2f1520-0469%282000%29057%3c1141%3aAGIITN%3e2.0.CO%3b2&partnerID=40&md5=22cfe8e8924ad45891a9ea91fdb4ac59","Spindown experiments have been conducted, using an atmospheric general circulation model, to determine the nature and timescale of adjustment to a baroclinically neutral state. The spindown was obtained by turning off the radiative cooling of the atmosphere-a procedure, the authors argue, that retains all the relevant constraints on the atmospheric motions. A further experiment with radiation and all other physical parameterizations turned off was performed for comparison. The neutral state was characterized by increased static stability but little reduction in meridional temperature gradient in the main baroclinic zones. However, the zones were observed to narrow and were flanked by regions where the meridional temperature gradient was reduced significantly. This pattern was repeated in the no-physics spin-down experiment but, in the absence of surface friction and strong orographic drag, the flow also appeared to be stabilized by enhanced barotropic shear. The neutral states from these two experiments are compared with those predicted by baroclinic adjustment theories and those seen in eddy life cycle experiments. The adjustment of temperature was roughly exponential, on a timescale of 15-20 days. A spin-up experiment was also performed where the radiation was turned back on in the adjusted state. The original climate was restored on a timescale of 5-10 days. Since both radiation and eddies are acting in the spinup, this implies a purely radiative forcing timescale of the same order as the adjustment timescale, which adds to the evidence that the mean atmospheric state cannot be said to be baroclinically adjusted.Spindown experiments have been conducted, using an atmospheric general circulation model, to determine the nature and timescale of adjustment to a baroclinically neutral state. The spindown was obtained by turning off the radiative cooling of the atmosphere-a procedure, the authors argue, that retains all the relevant constraints on the atmospheric motions. A further experiment with radiation and all other physical parameterizations turned off was performed for comparison. The neutral state was characterized by increased static stability but little reduction in meridional temperature gradient in the main baroclinic zones. However, the zones were observed to narrow and were flanked by regions where the meridional temperature gradient was reduced significantly. This pattern was repeated in the no-physics spin-down experiment but, in the absence of surface friction and strong orographic drag, the flow also appeared to be stabilized by enhanced barotropic shear. The neutral states from these two experiments are compared with those predicted by baroclinic adjustment theories and those seen in eddy life cycle experiments. The adjustment of temperature was roughly exponential, on a timescale of 15-20 days. A spin-up experiment was also performed where the radiation was turned back on in the adjusted state. The original climate was restored on a timescale of 5-10 days. Since both radiation and eddies are acting in the spinup, this implies a purely radiative forcing timescale of the same order as the adjustment timescale, which adds to the evidence that the mean atmospheric state cannot be said to be baroclinically adjusted."
"56000281400;7007108728;7004484970;7007012134;7003535385;","Dynamical and microphysical characteristics of Arctic clouds during BASE",2000,"10.1175/1520-0442(2000)013<1225:DAMCOA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034174263&doi=10.1175%2f1520-0442%282000%29013%3c1225%3aDAMCOA%3e2.0.CO%3b2&partnerID=40&md5=9d0efb1d9bc3578533bfc232813d7714","In this study, observations from aircraft, Doppler radar, and LANDSAT are used to better understand dynamical and microphysical characteristics of low-level Arctic clouds for climate change studies. Observations during the Beaufort and Arctic Storms Experiment were collected over the southern Beaufort Sea and the northern Mackenzie River Basin during 1 September-14 October 1994. Measurements from the cases of 8 September and 24-25 September are analyzed. In situ observations were made by instruments mounted on a Convair-580 research aircraft. Reflectivity and radial winds were obtained from an X-band Doppler radar located near Inuvik. The reflectivity field from LANDSAT observations concurrent with the aircraft and radar observations was also obtained. Dynamical activity, representing vertical air velocity (w(a)) and turbulent fluxes, is found to be larger in cloud regions. The sizes of coherent structures (e.g., cells) are from 0.1 to 15 km as determined by wavelet analysis and time series of aircraft data. This size is comparable with LANDSAT and Doppler radar-derived cell sizes. Reflectivity in embedded cells for the 8 September case was larger than that of single convective cells for the 24-25 September case. The effective radius for ice crystals (droplets) ranged from 37(7.5) μm to 70(9.5) μm for both cases. Using observations, parameterization of the ice crystal number concentration (N(i)) is obtained from a heat budget equation. Results showed that N(i) is a function of w(a), radiative cooling, particle size, and supersaturation. The large-scale models may have large uncertainties related to microphysical and dynamical processes (e.g., particle size and vertical air velocity, respectively), which can directly or indirectly influence radiative processes. Overall, the results suggest that the microphysical and dynamical properties of Arctic clouds need to be further explored for climate change studies.In this study, observations from aircraft, Doppler radar, and LANDSAT are used to better understand dynamical and microphysical characteristics of low-level Arctic clouds for climate change studies. Observations during the Beaufort and Arctic Storms Experiment were collected over the southern Beaufort Sea and the northern Mackenzie River Basin during 1 September-14 October 1994. Measurements from the cases of 8 September and 24-25 September are analyzed. In situ observations were made by instruments mounted on a Convair-580 research aircraft. Reflectivity and radial winds were obtained from an X-band Doppler radar located near Inuvik. The reflectivity field from LANDSAT observations concurrent with the aircraft and radar observations was also obtained. Dynamical activity, representing vertical air velocity (wa) and turbulent fluxes, is found to be larger in cloud regions. The sizes of coherent structures (e.g., cells) are from 0.1 to 15 km as determined by wavelet analysis and time series of aircraft data. This size is comparable with LANDSAT and Doppler radar-derived cell sizes. Reflectivity in embedded cells for the 8 September case was larger than that of single convective cells for the 24-25 September case. The effective radius for ice crystals (droplets) ranged from 37(7.5) μm to 70(9.5) μm for both cases. Using observations, parameterization of the ice crystal number concentration (Ni) is obtained from a heat budget equation. Results showed that Ni is a function of wa, radiative cooling, particle size, and supersaturation. The large-scale models may have large uncertainties related to microphysical and dynamical process (e.g., particle size and vertical air velocity, respectively), which can directly or indirectly influence radiative processes. Overall, the results suggest that the microphysical and dynamical properties of Arctic clouds need to be further explored for climate change studies."
"7004364155;6701599239;6604000335;6602885778;","Top-of-atmosphere albedo estimation from angular distribution models using scene identification from satellite cloud property retrievals",2000,"10.1175/1520-0442(2000)013<1269:TOAAEF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034174409&doi=10.1175%2f1520-0442%282000%29013%3c1269%3aTOAAEF%3e2.0.CO%3b2&partnerID=40&md5=93a57e1c77ddc2f3f1c0e80b1ea728fd","The next generation of earth radiation budget satellite instruments will routinely merge estimates of global top-of-atmosphere radiative fluxes with cloud properties. This information will offer many new opportunities for validating radiative transfer models and cloud parameterizations in climate models. In this study, five months of Polarization and Directionality of the Earth's Reflectances 670-nm radiance measurements are considered in order to examine how satellite cloud property retrievals can be used to define empirical angular distribution models (ADMs) for estimating top-of-atmosphere albedo. ADMs are defined for 19 scene types defined by satellite retrievals of cloud fraction and cloud optical depth. Two approaches are used to define the ADM scene types. The first assumes there are no biases in the retrieved cloud properties and defines ADMs for fixed discrete intervals of cloud fraction and cloud optical depth (fixed-τ approach). The second approach involves the same cloud fraction intervals, but uses percentile intervals of cloud optical depth instead (percentile-τ approach). Albedos generated using these methods are compared with albedos inferred directly from the mean observed reflectance field. Albedos based on ADMs that assume cloud properties are unbiased (fixed-τ approach) show a strong systematic dependence on viewing geometry. This dependence becomes more pronounced with increasing solar zenith angle, reaching ~12% (relative) between near-nadir and oblique viewing zenith angles for solar zenith angles between 60° and 70°. The cause for this bias is shown to be due to biases in the cloud optical depth retrievals. In contrast, albedos based on ADMs built using percentile intervals of cloud optical depth (percentile-τ approach) show very little viewing zenith angle dependence and are in good agreement with albedos obtained by direct integration of the mean observed reflectance field (<1% relative error). When the ADMs are applied separately to populations consisting of only liquid water and ice clouds, significant biases in albedo with viewing geometry are observed (particularly at low sun elevations), highlighting the need to account for cloud phase both in cloud optical depth retrievals and in defining ADM scene types. ADM-derived monthly mean albedos determined for all 5° X 5°lat-long regions over ocean are in good agreement (regional rms relative errors <2%) with those obtained by direct integration when ADM albedos inferred from specific angular bins are averaged together. Albedos inferred from near-nadir and oblique viewing zenith angles are the least accurate, with regional rms errors reaching ~5%-10% (relative). Compared to an earlier study involving Earth Radiation Budget Experiment ADMs, regional mean albedos based on the 19 scene types considered here show a factor-of-4 reduction in bias error and a factor-of-3 reduction in rms error.The next generation of earth radiation budget satellite instruments will routinely merge estimates of global top-of-atmosphere radiative fluxes with cloud properties. This information will offer many new opportunities for validating radiative transfer models and cloud parameterizations in climate models. In this study, five months of Polarization and Directionality of the Earth's Reflectances 670-nm radiance measurements are considered in order to examine how satellite cloud property retrievals can be used to define empirical angular distribution models (ADMs) for estimating top-of-atmosphere albedo. ADMs are defined for 19 scene types defined by satellite retrievals of cloud fraction and cloud optical depth. Two approaches are used to define the ADM scene types. The first assumes there are no biases in the retrieved cloud properties and defines ADMs for fixed discrete intervals of cloud fraction and cloud optical depth (fixed-τ approach). The second approach involves the same cloud fraction intervals, but uses percentile intervals of cloud optical depth instead (percentile-τ approach). Albedos generated using these methods are compared with albedos inferred directly from the mean observed reflectance field. Albedos based on ADMs that assume cloud properties are unbiased (fixed-τ approach) show a strong systematic dependence on viewing geometry. This dependence becomes more pronounced with increasing solar zenith angle, reaching ≈ 12% (relative) between near-nadir and oblique viewing zenith angles for solar zenith angles between 60° and 70°. The cause for this bias is shown to be due to biases in the cloud optical depth retrievals. In contrast, albedos based on ADMs built using percentile intervals of cloud optical depth (percentile-τ approach) show very little viewing zenith angle dependence and are in good agreement with albedos obtained by direct integration of the mean observed reflectance field (<1% relative error)."
"55337551400;35546736600;56528811300;56673482900;","Utilizing multiple datasets for snow-cover mapping",2000,"10.1016/S0034-4257(99)00099-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034108005&doi=10.1016%2fS0034-4257%2899%2900099-1&partnerID=40&md5=da26f0e894b383e366bf4e81dd116469","Snow-cover maps generated from surface data are based on direct measurements. However, they are prone to interpolation errors where climate stations are sparsely distributed. Snow cover is clearly discernible using satellite-obtained optical data because of the high albedo of snow, yet the surface is often obscured by cloud cover. Satellite-obtained passive microwave data, compared with optical data, is relatively unaffected by clouds; however, the snow-cover signature is significantly affected by melting snow and the microwaves may be transparent to thin snow (<3 cm). Both optical and microwave sensors have problems discerning snow beneath forest canopies. This paper describes a method that combines ground and satellite-derived optical and passive microwave data to produce a multiple-dataset snow-cover product. Comparisons with current snow-cover products show that the multiple-dataset product draws together the advantages of each of its component products while minimizing the potential errors. Improved estimates of the snow-covered area are derived through the addition of two snow-cover classes ('thin or patchy' and 'high elevation' snow cover) and from the analysis of the climate station data within each class. The compatibility of this method for use with Moderate Resolution Imaging Spectroradiometer data, which will be available in 1999, and with Advanced Microwave Scanning Radiometer data, available in 2000, is also discussed. With the assimilation of these data, the resolution of the multiple-dataset product would be improved both spatially and temporally and the analysis would become completely automated. (C) Elsevier Science Inc., 2000.Snow-cover maps generated from surface data are based on direct measurements. However, they are prone to interpolation errors where climate stations are sparsely distributed. Snow cover is clearly discernible using satellite-obtained optical data because of the high albedo of snow, yet the surface is often obscured by cloud cover. Satellite-obtained passive microwave data, compared with optical data, is relatively unaffected by clouds; however, the snow-cover signature is significantly affected by melting snow and the microwaves may be transparent to thin snow (<3 cm). Both optical and microwave sensors have problems discerning snow beneath forest canopies. This paper describes a method that combines ground and satellite-derived optical and passive microwave data to produce a multiple-dataset snow-cover product. Comparisons with current snow-cover products show that the multiple-dataset product draws together the advantages of each of its component products while minimizing the potential errors. Improved estimates of the snow-covered area are derived through the addition of two snow-cover classes (`thin or patchy' and `high elevation' snow cover) and from the analysis of the climate station data within each class. The compatibility of this method for use with Moderate Resolution Imaging Spectroradiometer data, which will be available in 1999, and with Advanced Microwave Scanning Radiometer data, available in 2000, is also discussed. With the assimilation of these data, the resolution of the multiple-dataset product would be improved both spatially and temporally and the analysis would become completely automated."
"7403208347;25930906600;","OH concentrations from a general circulation model coupled with a tropospheric chemistry model",2000,"10.1016/S1465-9972(99)00054-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034173769&doi=10.1016%2fS1465-9972%2899%2900054-9&partnerID=40&md5=25c61d4812b1a00fbb9da7586081886b","A comprehensive general circulation model has been coupled with a tropospheric chemistry model (TCM) using 'on-line' actinic flux calculation. The three-dimensional global distribution of OH was calculated and is presented in some detail. A 2-year integration generated a volume- and pressure-weighted global, tropospheric, annual mean OH concentration of 8.4 x 105 molecules/cm3. Over 70 gas phase reactions involving 28 chemical species were solved, using a two-step backward differentiation formula (BDF) combined with Gauss-Seidel iteration. The set of chemical equations was solved every model hour. 'On-line' actinic flux calculation allows for photo-radiation feedback between the two model components. Local changes in clouds and radiatively active gas concentrations directly affect the availability of actinic flux which has a direct impact on photochemistry through the photolysis rate constant. The actinic flux was efficiently calculated in each grid cell every model hour by the delta-Eddington radiation scheme of the general circulation model. The spectral resolution of the radiation scheme was 5 nm between 200 and 400 nm, 2 nm between 245 and 350 nm, and 25 nm between 350 and 700 nm. This provided for accurate calculations in the photolytically active spectral regions of O3 and NO2. (C) 2000 Elsevier Science Ltd.A comprehensive general circulation model has been coupled with a tropospheric chemistry model (TCM) using `on-line' actinic flux calculation. The three-dimensional global distribution of OH was calculated and is presented in some detail. A 2-year integration generated a volume- and pressure-weighted global, tropospheric, annual mean OH concentration of 8.4×105 molecules/cm3. Over 70 gas phase reactions involving 28 chemical species were solved, using a two-step backward differentiation formula (BDF) combined with Gauss-Seidel iteration. The set of chemical equations was solved every model hour. `On-line' actinic flux calculation allows for photo-radiation feedback between the two model components. Local changes in clouds and radiatively active gas concentrations directly affect the availability of actinic flux which has a direct impact on photochemistry through the photolysis rate constant. The actinic flux was efficiently calculated in each grid cell every model hour by the delta-Eddington radiation scheme of the general circulation model. The spectral resolution of the radiation scheme was 5 nm between 200 and 400 nm, 2 nm between 245 and 350 nm, and 25 nm between 350 and 700 nm. This provided for accurate calculations in the photolytically active spectral regions of O3 and NO2."
"57190531316;6506679005;6602601219;","Regional model simulations of African wave disturbances",2000,"10.1029/2000JD900017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033789623&doi=10.1029%2f2000JD900017&partnerID=40&md5=6e90ed0c76b1fe2cf42b23caa67c38d9","A regional climate simulation model is run at 50 km horizontal resolution over West Africa to study synoptic systems, such as African wave disturbances (AWDs). The study examines the results of 18 simulations, the longest of them covering the period August 8-15, 1988. Simulations were initialized with European Center for Medium-Range Weather Forecasts (ECMWF) gridded analysis data which also supply the lateral boundary conditions. Daily means of 700 mbar circulation and other model diagnostics are compared with ECMWF and National Centers for Environmental Prediction analyses to assess the skill of the model in simulating the evolution of synoptic systems. Trajectories of AWDs are tracked on time-longitude cross sections of 700 mbar vorticity, lower tropospheric divergence and precipitation rates. Cloud clusters on satellite imagery relate rather well to synoptic features on observational analyses as well as to spatial patterns of rain gage measurements but not consistently to simulated precipitation. Movement of major AWDs and the generation of new waves are handled realistically by the model. Model dynamics and physics appear to be more important than lateral boundary conditions in determining the course of simulations. Copyright 2000 by the American Geophysical Union."
"6701489771;7005432256;7004954379;7004877592;","A seasonal deuterium excess signal at Law Dome, coastal eastern Antarctica: A southern ocean signature",2000,"10.1029/1999JD901085","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033788319&doi=10.1029%2f1999JD901085&partnerID=40&md5=a0baa07860b58ba1d4b3c70df27dac01","The snow isotopic composition (δ18O and δD) of two shallow cores from the high accumulation summit region of Law Dome, east Antarctica, was measured at monthly resolution over the 1980-1992 period. While the δ18O or δD signals clearly reflect the local temperature cycle, the deuterium excess (d = δD-8δ18O) is shifted with respect to δ18O cycle by a 4 months lag. Interpretation of this phase lag is investigated using both an Atmospheric General Circulation Model (AGCM), which includes the water isotopic cycles, and a simple isotopic model, which better describes the microphysical processes within the cloud. Using this dual approach, we show that the seasonality of δ18O and d at Law Dome summit results from a combination of the southern ocean temperature cycle (shifted by 2-3 months with respect to the local insolation) and seasonal moisture origin changes due to a strong contribution of the local ocean when ice free. Both approaches are consistent with a dominant temperate to subtropical moisture origin. We thus demonstrate from our present-day subseasonal study that the record of d in the Dome Summit South (DSS) deep ice core represents a potential tool for identifying changes in Southern Ocean temperatures and/or sea ice cover at the scale of the past thousand years. Copyright 2000 by the American Geophysical Union."
"7003960899;","Insights into the importance of cloud vertical structure in climate",2000,"10.1029/1999GL011214","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353360&doi=10.1029%2f1999GL011214&partnerID=40&md5=f33e7a810001e37f01897edd67df31d5","Multi-year surface and satellite observations of cloud amounts have been combined to estimate the full three-dimensional structure of clouds for a three-layer atmosphere. This analysis provides new insight into the vertical structure of clouds and the interactions with atmospheric radiation. For instance, a simple vertical overlap parameter has been derived which is very consistent with general climatology. In addition radiative transfer model calculations show that both the mean net heating rates within the atmosphere and the perturbations of cloud radiative forcing at the top are very sensitive to variations in the overlap parameter."
"55896920900;6701596624;56706602500;8380252900;7404369915;6603892183;","Radiative properties of boundary layer clouds: Droplet effective radius versus number concentration",2000,"10.1175/1520-0469(2000)057<0803:RPOBLC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034062157&doi=10.1175%2f1520-0469%282000%29057%3c0803%3aRPOBLC%3e2.0.CO%3b2&partnerID=40&md5=51cf96fa43e4d4df86c7dbd3b172f97f","The plane-parallel model for the parameterization of clouds in global climate models is examined in order to estimate the effects of the vertical profile of the microphysical parameters on radiative transfer calculations for extended boundary layer clouds. The vertically uniform model is thus compared to the adiabatic stratified one. The validation of the adiabatic model is based on simultaneous measurements of cloud microphysical parameters in situ and cloud radiative properties from above the cloud layer with a multispectral radiometer. In particular, the observations demonstrate that the dependency of cloud optical thickness on cloud geometrical thickness is larger than predicted with the vertically uniform model and that it is in agreement with the prediction of the adiabatic one. Numerical simulations of the radiative transfer have been performed to establish the equivalence between the two models in terms of the effective radius. They show that the equivalent effective radius of a vertically uniform model is between 80% and 100% of the effective radius at the top of an adiabatic stratified model. The relationship depends, in fact, upon the cloud geometrical thickness and droplet concentration. Remote sensing measurements of cloud radiances in the visible and near infrared are then examined at the scale of a cloud system for a marine case and the most polluted case sampled during the second Aerosol Characterization Experiment. The distributions of the measured values are significantly different between the two cases. This constitutes observational evidence of the aerosol indirect effect at the scale of a cloud system. Finally, the adiabatic stratified model is used to develop a procedure for the retrieval of cloud geometrical thickness and cloud droplet number concentration from the measurements of cloud radiances. It is applied to the marine and to the polluted cases. The retrieved values of droplet concentration are significantly underestimated with respect to the values measured in situ. Despite this discrepancy the procedure is efficient at distinguishing the difference between the two cases.The plane-parallel model for the parameterization of clouds in global climate models is examined in order to estimate the effects of the vertical profile of the microphysical parameters on radiative transfer calculations for extended boundary layer clouds. The vertically uniform model is thus compared to the adiabatic stratified one. The validation of the adiabatic model is based on simultaneous measurements of cloud microphysical parameters in situ and cloud radiative properties from above the cloud layer with a multispectral radiometer. In particular, the observations demonstrate that the dependency of cloud optical thickness on cloud geometrical thickness is larger than predicted with the vertically uniform model and that it is in agreement with the prediction of the adiabatic one. Numerical simulations of the radiative transfer have been performed to establish the equivalence between the two models in terms of the effective radius. They show that the equivalent effective radius of a vertically uniform model is between 80% and 100 of the effective radius at the top of an adiabatic stratified model. The relationship depends, in fact, upon the cloud geometrical thickness and droplet concentration. Remote sensing measurements of cloud radiances in the visible and near infrared are then examined at the scale of a cloud system for a marine case and the most polluted case sampled during the second Aerosol Characterization Experiment. The distributions of the measured values are significantly different between the two cases. This constitutes observational evidence of the aerosol indirect effect at the scale of a cloud system. Finally, the adiabatic stratified model is used to develop a procedure for the retrieval of cloud geometrical thickness and cloud droplet number concentration from the measurements of cloud radiances. It is applied to the marine and to the polluted cases. The retrieved values of droplet concentration are significantly underestimated with respect to the values measured in situ. Despite this discrepancy the procedure is efficient at distinguishing the difference between the two cases."
"7202912430;6506750105;7004070482;55907891100;","Observations of the breakdown of an atmospheric gravity wave near the cold summer mesopause at 54N",2000,"10.1029/1999GL010792","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353345&doi=10.1029%2f1999GL010792&partnerID=40&md5=b6b71377fdcbc16588cb156c0003d1cb","Recently, it was shown from a single set of airglow-lidar observations in Urbana, Illinois (40N) that some small-scale wave-like structure seen in OH airglow images can be associated with the breakdown, via a convective instability, of an atmospheric gravity wave. A second set of simultaneous airglow/lidar observations, showing wave breakdown, has been obtained over Kuhlungsborn, Germany (54N) during a period when noctilucent clouds (NLCs) were also observed. This showed that the wave breakdown process can occur under the same cold, low altitude summer mesopause conditions that support the occurrence of NLCs. This new set of data shows that the first observations were not a unique event, and give credence to the suggestion that some of the small scale structure seen in NLC displays may be due to wave breakdown."
"7004479957;7003971889;","An interpretation of the results from atmospheric general circulation models forced by the time history of the observed sea surface temperature distribution",2000,"10.1029/1999GL010910","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353321&doi=10.1029%2f1999GL010910&partnerID=40&md5=6ccd5e822137760be19d583c68a53223","Recent studies using atmospheric general circulation models forced by the observed time history of global sea surface temperature anomalies have been used to hindcast the temporal history of the North Atlantic Oscillation. They find that the mean of a large ensemble of integrations using slightly different initial atmospheric conditions reproduces the observed variability surprisingly well, especially on time scales longer than a few years. However, they also find that amplitude of the atmospheric variability is considerably reduced and the air-sea heat fluxes are of the reverse sign to those observed. Here, a linear model of midlatitude atmosphere/ocean interaction forced only by high-frequency atmospheric stochastic variability is shown to reproduce all of these findings. This model suggests that despite the hindcast skill, the useful predictability associated with midlatitude SST anomalies may be limited to one or two seasons."
"35618049800;7102577095;6603568514;","Sensitivity of cloud and radiation parameterizations to changes in vertical resolution",2000,"10.1175/1520-0442(2000)013<0915:SOCARP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033949152&doi=10.1175%2f1520-0442%282000%29013%3c0915%3aSOCARP%3e2.0.CO%3b2&partnerID=40&md5=d567c00c078fca2799d8290da04aad73","The importance of vertical resolution to the parameterization of cloud-radiation processes in climate models is examined. Using a one-dimensional single-column model containing a typical suite of physical parameterizations, the authors test 12 different vertical resolutions, ranging from 16 to 60 layers. The model products are evaluated against observational data taken during three intensive observation periods from the Atmospheric Radiation Measurement Program. The simulated values of cloud-radiation variables display a marked sensitivity to changes in vertical resolution. This sensitivity is apparent in all the model variables examined. The cloud fraction varies typically by approximately 10% over the range of resolutions tested, a substantial amount when compared to the typical observed values of about 50%. The outgoing longwave radiation typically changes by approximately 10-20 W m2 as resolution is varied, which is of the order of 5%-10% of the observed value. The downwelling shortwave radiation change is somewhat smaller but is still significant. Furthermore, the model results have not converged even at a resolution of 60 layers, and there are systematic differences between model results and observations. © 2000 American Meteorological Society."
"7005822617;7003975565;7004538613;7203066817;","Can the foliar nitrogen concentration of upland vegetation be used for predicting atmospheric nitrogen deposition? Evidence from field surveys",2000,"10.1016/S0269-7491(99)00166-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033954550&doi=10.1016%2fS0269-7491%2899%2900166-9&partnerID=40&md5=25ebb76b325395dbef5d2c26b62390ba","The deposition of atmospheric nitrogen can be enhanced at high altitude sites as a consequence of cloud droplet deposition and orographic enhancement of wet deposition on hills. The degree to which the increased deposition of nitrogen influences foliar nitrogen concentration in a range of upland plant species was studied in a series of field surveys in northern Britain. A range of upland plant species sampled along altitudinal transects at sites of known atmospheric nitrogen deposition showed marked increases in foliar nitrogen concentration with increasing nitrogen deposition and altitude (and hence with decreasing temperature). For Nardus stricta L., Deschampsia flexuosa (L.) Trin., Calluna vulgaris (L.) Hull, Erica cinerea L. and Hylocomium splendens (Hedw.) Br. Eur. on an unpolluted hill, foliar nitrogen increased by 0.07, 0.12, 0.15, 0.08 and 0.04% dry weight respectively for each 1 kg ha-1 year-1 increase in nitrogen deposition. Most species showed an approximately linear relationship between foliar nitrogen concentration and altitude but no trend with altitude for foliar phosphorus concentration. This provided evidence that the tissue nutrient status of upland plants reflects nutrient availability rather than the direct effects of climate on growth. However, differences in the relationship between foliar nitrogen concentration and atmospheric nitrogen deposition for N. stricta sampled on hills in contrasting pollution climates show that the possibility of temperature-mediated growth effects on foliar nitrogen concentration should not be ignored. Thus, there is potential to use upland plant species as biomonitors of nitrogen deposition, but the response of different species to nitrogen addition, in combination with climatic effects on growth, must be well characterised. Copyright (C) 2000 Elsevier Science Ltd."
"7003922138;","Tropical cooling at the last glacial maximum: An atmosphere-mixed layer ocean model simulation",2000,"10.1175/1520-0442(2000)013<0951:TCATLG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033949153&doi=10.1175%2f1520-0442%282000%29013%3c0951%3aTCATLG%3e2.0.CO%3b2&partnerID=40&md5=fce3f24039f6dc6ecab552f1a7448b54","The sensitivity of tropical temperature to glacial forcing is examined by using an atmosphere-mixed layer ocean (A-MLO) model to simulate the climate of the last glacial maximum (LGM) following specifications established by the Paleoclimate Modeling Intercomparison Project. Changes in continental ice, orbital parameters, atmospheric CO2, and sea level constitute a global mean radiative forcing of -4.20 W m-2, with the vast majority of this forcing coming, in nearly equal portions, from the changes in continental ice and CO2. In response to this forcing, the global mean surface air temperature decreases by 4.0 K, with the largest cooling in the extratropical Northern Hemisphere. In the Tropics, a more modest cooling of 2.0 K (averaged from 30°N to 30°S) is simulated, but with considerable spatial variability resulting from the interhemispheric asymmetry in radiative forcing, contrast between oceanic and continental response, advective effects, and changes in soil moisture. Analysis of the tropical energy balance reveals that the decrease in top-of-atmosphere longwave emission associated with the tropical cooling is balanced primarily by the combination of increased reflection of shortwave radiation by clouds and increased atmospheric heat transport to the extratropics. Comparisons with a variety of paleodata indicate that the overall tropical cooling is comparable to paleoceanographic reconstructions based on alkenones and species abundances of planktonic microorganisms, but smaller than the cooling inferred from noble gases in aquifers, pollen, snow line depression, and the isotopic composition of corals. The differences in the magnitude of tropical cooling reconstructed from the different proxies preclude a definitive evaluation of the realism of the tropical sensitivity of the model. Nonetheless, the comparisons with paleodata suggest that it is unlikely that the A-MLO model exaggerates the actual climate sensitivity. The similarity between the sensitivity coefficients (i.e., the ratio of the change in global mean surface air temperature to the change in global mean radiative forcing) for the LGM simulation and a simulation of CO2 doubling suggests that similar climate feedbacks are involved in the responses to these two perturbations. More comprehensive simulation of the tropical temperature sensitivity to glacial forcing will require the use of coupled models, for which a number of technical obstacles remain."
"6602681695;","Trends in nordic and arctic temperature extremes and ranges",2000,"10.1175/1520-0442(2000)013<0977:TINAAT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033937817&doi=10.1175%2f1520-0442%282000%29013%3c0977%3aTINAAT%3e2.0.CO%3b2&partnerID=40&md5=d99dd945a1c2366da7139a4590357599","The national meteorological institutes in the Nordic countries have produced a comprehensive dataset of climatic extreme temperatures (monthly mean daily maximum and minimum, and monthly absolute highest and lowest temperatures) comprising stations from Fenno-Scandia, the Nordic Seas, and Greenland. Mean maximum and minimum temperatures show statistically significant negative trends in western coastal Greenland during the period 1950-95, while over the Nordic Seas and Fenno-Scandia the trends are generally positive. The diurnal temperature range (DTR) is decreasing significantly throughout the study area and is unrelated to regional temperature trends, which show both warming and cooling. The opposite temperature trends between western coastal Greenland and Fenno-Scandia since the 1950s are in accordance with a strengthening of the North Atlantic Oscillation (NAO). However, the simple NAO index fails to explain the decrease of DTR. In FennoScandia, the reliable long-term mean maximum and minimum temperatures show cooling in winter and warming in spring and summer during the period 1910-95. Simultaneously, DTR has been decreasing in all seasons except winter. Most of the decrease has occurred since the 1940s. Atmospheric circulation indices defined by zonal and meridional sea level pressure differences, along with sea level pressure and cloud cover anomalies were used to build a multiple linear regression model for the Fenno-Scandian DTR. During the period 1910-95 the model explains from 53% (winter) to 80% (summer) of the variation in DTR and reproduces the statistically significant decreasing trend on annual level. Cloud cover is the dominant predictor, while circulation provides substantial improvement in explanation. © 2000 American Meteorological Society."
"57208460923;7402178817;7103402055;7402018703;","Boundary layer ozone in the tropical America northern hemisphere region",2000,"10.1023/A:1006270911796","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0343986290&doi=10.1023%2fA%3a1006270911796&partnerID=40&md5=6a91e3b4be1e0abf213d838e699ac0c4","In recent field campaigns, boundary layer ozone concentrations were measured at different sites in the Orinoco river basin (mainly savannahs) and nearby locations (cloud forest and coastal sites), during dry and wet seasons. The results provide a comprehensive description of boundary layer ozone in a tropical region north of the equator where scarce information is available. Ozone measurements were made using photometric ozone analyzers. In the savannah region, ozone profiles (up to 1000 m) were also obtained using electrochemical concentration cell sondes, launched in a tethered balloon. The results, in comparison with other parts of the world, confirm the low values for the concentration of ozone in the boundary layer of the study region. Throughout the entire region (marine, coastal, and continental areas), higher concentrations were produced during the dry season (20-30 ppbv) than during the wet season (13-17 ppbv), likely due to the photochemical production of ozone from biomass burning emissions. This seasonal variation observed in the boundary layer contrasts with satellite data, that show higher total tropospheric ozone columns during the wet season in the 0-15°N region; this means that the ozone annual cycles in the boundary layer and free troposphere are out of phase. At the most pristine continental sites in the southern part of Venezuela, quite a 'peculiar' diurnal variation was observed, with maximum concentrations in the morning and a steady decrease of ~ 0.6 ppbv hr-1 during the hours of high solar irradiation. Although dynamic aspects cannot be ruled out, the daytime ozone decrease, which cannot be explained by the well-established 'classical' continental O3 sinks, suggests that in this region part of the ozone consumption is caused by HO(x) cycles at low NO(x) levels. Future studies to elucidate the causes of the daytime ozone decrease at these continental sites should be undertaken."
"7003278104;7102389501;","Analysis of ocean surface heat fluxes in a NOGAPS climate simulation: Influences from convection, clouds and dynamical processes",2000,"10.1029/1999JD901028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046528304&doi=10.1029%2f1999JD901028&partnerID=40&md5=e684c068ba3edb34ff893cac435c2428","This study examines the simulation quality of the surface heat flux fields produced during a climate simulation of the Navy Operational Global Atmospheric Prediction System, version 3.4, with a reduced spectral truncation of T63 and 18 levels (herineafter referred to as NOGAPS-CL). Comparisons are made between a 17-year NOGAPS-CL simulation using monthly sea surface temperatures as surface boundary conditions and a number of validating data sets consisting of ship, satellite, and/or reanalysis-based surface heat fluxes, precipitation, top of the atmosphere radiation budget, water vapor, cloud frequency, surface wind stress, and tropospheric winds. In this extended, long-range integration, NOGAPS-CL underpredicts the net surface shortwave flux in much of the subtropical oceans and overpredicts the net shortwave flux in the western Pacific warm pool and the midlatitude oceans, when compared to several satellite-derived climatological data sets. In addition, NOGAPS-CL over predicts the latent heat flux in much of the subtropics and under predicts the latent heat flux over the northern ocean western boundary currents and under the storm track regions that extend eastward from them. These shortwave and evaporation biases combine to produce errors in the surface net heat flux, with too little heat entering the subtropical/tropical oceans and too much heat loss in the midlatitudes oceans. Examination of related quantities indicates that the tropical climate biases are coupled to shortcomings in the convective cloud and/or boundary layer parameterizations which leads to the premature release of moist instability from the boundary layer in regions just outside the deep convective zones. This leads to enhanced climatological cloudiness, rainfall, and surface evaporation, as well as to a reduction in the surface shortwave flux and outgoing longwave radiation (OLR), in the subtropical regions. Furthermore, because of this early release of the moist static energy, there is a reduction in clouds, rainfall and water vapor content, as well as enhanced surface shortwave flux and outgoing longwave radiation, in the deep convective zones. The reduction in rainfall and enhanced OLR reduces the strength of the tropical large-scale circulation, which in turn reduces the strength of the subsidence in the subtropical regions which normally acts to suppress the convection processes in these regions. The implications of these results are discussed in terms of the relationship among the forecast model climatological surface fluxes, convection, clouds, and the dynamical processes, as well as their similarities to other climate models and their possible impact on the simulation of transient systems. Copyright 2000 by the American Geophysical Union."
"57198116947;6504816695;6506423470;","Fractal properties and denoising of lidar signals from cirrus clouds",2000,"10.1029/1999JD900972","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033792451&doi=10.1029%2f1999JD900972&partnerID=40&md5=e24d618edda873e083fc4041d401c88f","Airborne lidar signals of cirrus clouds are analyzed to determine the cloud structure. Climate modeling and numerical weather prediction benefit from accurate modeling of cirrus clouds. Airborne lidar measurements of the European Lidar in Space Technology Experiment (ELITE) campaign were analyzed by combining shots to obtain the backscatter at constant altitude. The signal at high altitude was analyzed for horizontal structure of cirrus clouds. The power spectrum and the structure function show straight lines on a double logarithmic plot. This behavior is characteristic for a Brownian fractal. Wavelet analysis using the Haar wavelet confirms the fractal aspects. It is shown that the horizontal structure of cirrus can be described by a fractal with a dimension of 1.8 over length scales that vary 4 orders of magnitude. We use the fractal properties in a new denoising method. Denoising is required for future lidar measurements from space that have a low signal to noise ratio. Our wavelet denoising is based on the Haar wavelet and uses the statistical fractal properties of cirrus clouds in a method based on the maximum a posteriori (MAP) probability. This denoising based on wavelets is tested on airborne lidar signals from ELITE using added Gaussian noise. Superior results with respect to averaging are obtained. Copyright 2000 by the American Geophysical Union."
"7202559581;","Interpolation of surface radiative temperature measured from polar orbiting satellites to a diurnal cycle 2. Cloudy-pixel treatment",2000,"10.1029/1999JD901088","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033793048&doi=10.1029%2f1999JD901088&partnerID=40&md5=20611c758dc5ba9f858fc1cb5ae242e0","Global skin temperature is very important for the understanding of surface climate and for evaluating climate models. However, when the surface is obscured by clouds, this variable cannot be measured directly by using satellite thermal infrared channels. Methods for calculating skin temperature for a satellite cloudy pixel are important, yet little research on their relative merits has been done. The ""cloudy-pixel treatment"" presented here is a hybrid technique of ""neighboring-pixel"" and ""surface air temperature"" approaches. The neighboring-pixel approach (NP) for calculating skin temperature for a satellite cloudy pixel is described and tested against field experiments and climate model CCM3/BATS simulations. This approach is based on the surface energy balance with the soil heat flux being treated by a conventional force-restore method for bare soil and short vegetated surfaces, where ground heat flux is important. For other surfaces where soil heat flux is less important, for example, the fully vegetated forests in temperate and tropical regions, observed empirical relationships between solar radiative energy and skin temperature (i.e., ΔSn/ΔTs) are used. In addition, a ""surface air temperature (Ta) adjustment"" is developed from the Monin-Obukhov similarity theory to infer skin temperature from 2-m air temperature using a knowledge of wind speed, pressure, boundary layer stability, and other surface properties. This adjustment is useful wherever surface air temperatures are available to insure the skin temperature consistency during daytime and nighttime. Error analyses show that this cloudy-pixel treatment has an accuracy of 1°-2° K at monthly mean pixel level resolution. This accuracy varies with season and vegetation type. Despite the uncertainty in this algorithm, this work can be practically used to calculate skin temperature for a cloudy pixel. Copyright 2000 by the American Geophysical Union."
"7003600071;7005184190;7005068935;6701511321;6603794982;","A polar stratospheric cloud parameterization for the global modeling initiative three-dimensional model and its response to stratospheric aircraft",2000,"10.1029/1999JD900932","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033788038&doi=10.1029%2f1999JD900932&partnerID=40&md5=f7c5496467afdfc926d077a590a293dc","We describe a new parameterization of polar stratospheric clouds (PSCs) which was written for and incorporated into the three-dimensional (3-D) chemistry and transport model (CTM) developed for NASA's Atmospheric Effects of Aviation Project (AEAP) by the Global Modeling Initiative (GMI). The parameterization was designed to respond to changes in NOy and H2O produced by high-speed civilian transport (HSCT) emissions. The parameterization predicts surface area densities (SADs) of both Type 1 and Type 2 PSCs for use in heterogeneous chemistry calculations. Type 1 PSCs are assumed to have a supercooled ternary sulfate (STS) composition, and Type 2 PSCs are treated as water ice with a coexisting nitric acid trihydrate (NAT) phase. Sedimentation is treated by assuming that the PSC particles obey lognormal size distributions, resulting in a realistic mass flux of condensed phase H2O and HNO3. We examine a simulation of the Southern Hemisphere high-latitude lower stratosphere winter and spring seasons driven by temperature and wind fields from a modified version of the National Center for Atmospheric Research (NCAR) Middle Atmosphere Community Climate Model Version 2 (MACCM2). Predicted PSC SADs and median radii for both Type 1 and Type 2 PSCs are consistent with observations. Gas phase HNO3 and H2O concentrations in the high-latitude lower stratosphere qualitatively agree with Cryogenic Limb Array Etalon Spectrometer (CLAES) HNO3 and Microwave Limb Sounder (MLS) H2O observations. The residual denitrification and dehydration of the model polar vortex after polar winter compares well with atmospheric trace molecule spectroscopy (ATMOS) observations taken during November 1994. When the NOx and H2O emissions of a standard 500-aircraft HSCT fleet with a NOx emission index of 5 are added, NOx and H2O concentrations in the Southern Hemisphere polar vortex before winter increase by up to 3%. This results in earlier onset of PSC formation, denitrification, and dehydration. Active Cly increases and produces small (∼1%) decreases in lower stratospheric vortex O3 concentrations during the spring relative to the HSCT-free run. Copyright 2000 by the American Geophysical Union."
"35390825100;35396858200;7202081585;57136469800;7004292082;7103306240;6507366126;35405390200;6508309003;8386790800;","Tropospheric water vapor measurements over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX)",2000,"10.1029/1999JD901019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033787760&doi=10.1029%2f1999JD901019&partnerID=40&md5=fbe2f59943870242a366acf81096a899","Fast-response tunable diode laser measurements of water vapor were made over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) conducted in the fall of 1997. Resulting water vapor mixing ratios, in conjunction with air temperature and pressure measurements obtained by the DC-8's Data Acquisition and Distribution System (DADS), were used to calculate the prevalence of ice-saturated conditions (relative humidity with respect to ice > 100% or frost saturation) in the upper troposphere over the SONEX sampling region. Additionally, Appleman theory was applied to the data to determine the subset of ice-saturated regions which would support formation of contrails. Results suggest that studies to determine the potential climate or radiative impact of contrails and aviation-induced cirrus clouds should not only consider the climatology of frost-saturated regions, but should also address whether ambient conditions can support contrail formation within these regions. A separate discussion within the paper describes an in-flight intercomparison between the SONEX diode laser hygrometer and the Pollution From Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT 2) cryogenic hygrometer and shows that the instruments perform to within their stated accuracies (∼10%) over a range of mixing ratios and altitudes. Copyright 2000 by the American Geophysical Union."
"7202404301;7203054240;35550043200;","The influence of convective outflow on water vapor mixing ratios in the tropical upper troposphere: An analysis based on UARS MLS measurements",2000,"10.1029/1999GL010477","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353441&doi=10.1029%2f1999GL010477&partnerID=40&md5=f019a1f6265843c1b21bcdc0de31b3bd","The source of increased water vapor mixing ratios over the central and eastern tropical Pacific region during the 1992 El Nino event is examined using measurements of upper tropospheric water vapor provided by the Microwave Limb Sounder (MLS) on board the Upper Atmosphere Research Satellite. Horizontal winds on isentropic surfaces are combined with ISCCP cloud information to provide back-trajectory calculations free of high clouds. These calculations show that the water vapor mixing ratio of an air parcel in the cloud-free regions of the eastern Pacific decreases to approximately one-half of its original value within the first 30 hours after encountering deep convection. This analysis also finds a larger number of air parcels encountering deep convection within 30 hours of observation, and therefore having higher mixing ratios, in March-April 1992 compared to March-April 1994. Hence, increased deep convection over the equatorial central and eastern Pacific in 1992 contributed to the moistening of the downstream tropical upper troposphere."
"7202048299;7003545639;","The impact of clouds on the seasonal cycle of radiative heating over the Pacific",2000,"10.1175/1520-0469(2000)057<0545:TIOCOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0343729957&doi=10.1175%2f1520-0469%282000%29057%3c0545%3aTIOCOT%3e2.0.CO%3b2&partnerID=40&md5=44c4358a2f59f8041358a4a574d6d359","Seasonal variations of cloud radiative forcing (CRF) are calculated from observed cloud properties in the International Satellite Cloud Climatology Project over the Pacific between 30°S and 30°N. Using 7 yr of data, the first annual harmonic of CRF is statistically significant with respect to the background red noise spectrum at better than a 0.99 confidence level at most locations. It is significant with respect to calculation error at better than a 0.90 confidence level at those same locations. Calculated annual variations are strongest in the subtropics and equatorial east Pacific. In a linear analysis, annual variations of CRF are attributed to individual annual variations of cloud properties, insolation, or surface temperature. At higher latitudes, the seasonal cycle of CRF at the top of the atmosphere (TOA) and at the surface is dominated by the shortwave (SW) component and results primarily from the seasonal cycle of insolation interacting with the time mean cloud field. Annual variations of cloud fraction and of cloud optical depth are both important in the Tropics, particularly in the east Pacific. Longwave (LW) CRF at TOA is strongest at locations where the seasonal cycle of convection is strong. At those locations, annual variations of CRF result primarily from annual variations of cloud height and not from annual variations of cloud fraction. At the surface, annual variations of LW CRF are shall throughout. The annual variations of atmospheric CRF are dominated by the LW component, with the SW component contributing about 20%. As with LW CRF at TOA, annual variations of atmospheric CRF are strongest over convective locations and result from annual variations of cloud height. The impact of cloud radiative forcing on zonal circulations in the equatorial Pacific and on SST in the east Pacific was analyzed. CRF represents approximately 20% of the annual variations of diabatic heating rates over convective locations and 50% or better at nonconvective locations. Annual variations of atmospheric CRF, when strong, tend to be in phase with those of total diabatic heating rates, indicating that clouds reinforce tropical circulations driven by latent heating. The role of clouds is particularly important in the east Pacific between 85°and 105°W. Atmospheric CRF is a major component of total diabatic heating over the cold tongue, where seasonal variations of SST are strongest. If seasonal variations of SST in the cold tongue result from seasonal variations of upwelling driven by meridional wind variability, then CRF may play an important role. In contrast, CRF at the surface has only a weak seasonal cycle, with a phase that is not consistent as a forcing for seasonal variations of SST.Seasonal variations of cloud radiative forcing (CRF) are calculated from observed cloud properties in the International Satellite Cloud Climatology Project over the Pacific between 30°S and 30°N. Using 7 yr of data, the first annual harmonic of CRF is statistically significant with respect to the background red noise spectrum at better than a 0.99 confidence level at most locations. It is significant with respect to calculation error at better than a 0.90 confidence level at those same locations. Calculated annual variations are strongest in the subtropics and equatorial east Pacific. In a linear analysis, annual variations of CRF are attributed to individual annual variations of cloud properties, insolation, or surface temperature. At higher latitudes, the seasonal cycle of CRF at the top of the atmosphere (TOA) and at the surface is dominated by the shortwave (SW) component and results primarily from the seasonal cycle of insolation interacting with the time mean could field. Annual variations of cloud fraction and of cloud optical depth are both important in the Tropics, particularly in the east Pacific. Longwave (LW) CRF at TOA is strongest at locations where the seasonal cycle of convection is strong. At those locations, annual variations of CRF result primarily from annual variations of cloud height and not from annual variations of cloud fraction. At the surface, annual variations of LW CRF are small throughout. The annual variations of atmospheric CRF are dominated by the LW component, with the SW component contributing about 20%. As with LW CRF at TOA, annual variations of atmospheric CRF are strongest over convective locations and result from annual variations of cloud height. The impact of cloud radiative forcing on zonal circulations in the equatorial Pacific and on SST in the east Pacific was analyzed. CRF represents approximately 20% of the annual variations of diabatic heating rates over convective locations and 50% or better at nonconvective locations. Annual variations of atmospheric CRF, when strong, tend to be in phase with those of total diabatic heating rates, indicating that clouds reinforce tropical circulations driven by latent heating. The role of clouds is particularly important in the east Pacific between 85° and 105°W. Atmospheric CRF is a major component of total diabatic heating over the cold tongue, where seasonal variations of SST are strongest. If seasonal variations of SST in the cold tongue result from seasonal variations of upwelling driven by meridional wind variability, then CRF may play an important role. In contrast, CRF at the surface has only a weak seasonal cycle, with a phase that is not consistent as a forcing for seasonal variations of SST."
"6603079636;6603531546;","Modelling global radiation in complex terrain: Comparing two statistical approaches",2000,"10.1016/S0168-1923(99)00141-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034607073&doi=10.1016%2fS0168-1923%2899%2900141-0&partnerID=40&md5=1ce9e5f2b25b965bb686a38d55cf970b","Two simple approaches for assessing global radiation in complex terrain are tested and compared. A parameterisation scheme for global radiation based on cloud cover observations was compared with interpolation of measured global radiation values from the Austrian climate observation network. Interpolation appears to be a useful method for a station density which has been available after 1992 in Austria (about 1000 km2/station). In that case interpolation is superior to parameterisation. The quality of interpolated data quickly drops with height and for elevations above 1500 m neither method delivers useful results. (C) 2000 Elsevier Science B.V."
"7004202450;7102021223;","Net cloud radiative forcing at the top of the atmosphere in the Asian monsoon region",2000,"10.1175/1520-0442(2000)013<0650:NCRFAT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034143862&doi=10.1175%2f1520-0442%282000%29013%3c0650%3aNCRFAT%3e2.0.CO%3b2&partnerID=40&md5=775b9931776b6780102ada3a09c527b1","Based on the data from Earth Radiation Budget Experiment (ERBE), many investigators have concluded that the net cloud radiative forcing at the top of the atmosphere is small in the deep convective region of the Tropics. This conclusion has been shown to be invalid for the Asian monsoon region during the period June-September. The ERBE data have been used to show that in the Asian monsoon region the net cloud radiative forcing at the top of the atmosphere is negative and its magnitude exceeds 30 W m-2 in 25% of the grids in this region. The large negative net cloud radiative forcing in the Asian monsoon region during June-September has been shown to be on account of the presence of large amount of high clouds and the large optical depth of these clouds. This combination of high cloud amount and high optical depth occurs in the Asian monsoon region only. In the other deep convective regions of the Tropics, high clouds with large optical depths are present, but they do not cover a large area.Based on the data from Earth Radiation Budget Experiment (ERBE), many investigators have concluded that the net cloud radiative forcing at the top of the atmosphere is small in the deep convective region of the Tropics. This conclusion has been shown to be invalid for the Asian monsoon region during the period June-September. The ERBE data have been used to show that in the Asian monsoon region the net cloud radiative forcing at the top of the atmosphere is negative and its magnitude exceeds 30 W m-2 in 25% of the grids in this region. The large negative net cloud radiative forcing in the Asian monsoon region during June-September has been shown to be on account of the presence of large amount of high clouds and the large optical depth of these clouds. This combination of high cloud amount and high optical depth occurs in the Asian monsoon region only. In the other deep convective regions of the Tropics, high clouds with large optical depths are present, but they do not cover a large area."
"7003627515;","The semi-annual oscillation and antarctic climate. Part 3: The role of near-surface wind speed and cloudiness",2000,"10.1002/(SICI)1097-0088(200002)20:2<117::AID-JOC481>3.0.CO;2-B","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034088674&doi=10.1002%2f%28SICI%291097-0088%28200002%2920%3a2%3c117%3a%3aAID-JOC481%3e3.0.CO%3b2-B&partnerID=40&md5=968d6fc515f34c7b168c15c5d4d957a1","The interactions between the semi-annual oscillation (SAO), near-surface wind speed and cloudiness at seven Antarctic stations are described, as is how near-surface temperature is affected. A firmly established half-yearly wave, in both the mean annual cycle of wind speed and of cloudiness, was found at two stations with limited local disturbances: Halley and Faraday. Following a significant weakening of the SAO since the late 1970s, the annual cycles of wind speed and cloudiness at these stations have changed accordingly: increased wind speed and cloudiness in solstitial months and a decrease in the equinoctial months. At Halley, where no significant long-term temperature trends are detectable, this explains the observed changes in the seasonal temperature cycle. At Faraday, annual mean wind speed and cloudiness are negatively correlated to SAO strength, and as a result both have recently increased. Based on the correlation between wind speed and temperature changes, we estimate a 'background' (independent of circulation changes) Antarctic warming trend of 1.29 ± 0.48°C per century. Copyright (C) 2000 Royal Meteorological Society."
"6602628376;36819227800;7403170444;6602974821;6602517262;7402943892;","Factors, especially sunspot number, causing variations in surface air concentrations and depositions of 7Be in Osaka, Japan",2000,"10.1029/1999GL010801","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353470&doi=10.1029%2f1999GL010801&partnerID=40&md5=38e1a2f8e86898394b9b081342b24ca1","We found that increasing sunspot number caused a significant negative effect on monthly and yearly average air concentration and yearly deposition of 7Be. For more than 15 years monthly average surface air concentration and monthly deposition of 7Be was measured in Osaka, Japan. The maximum monthly average surface air concentration of 7Be was 1.6 times higher than the minimum concentration through the fifteen year measurement span. Increase of several percent in the monthly averaged surface air concentration and monthly deposition of 7Be were observed in the monthly mean for February-March-April 1987 period following the 23 February supernova explosion in the Large Magellanic Cloud. The seasonal variation pattern which includes the lowest surface air concentration of 7Be in summer is due to the transport of air masses from low latitudes carrying low 7Be concentrations into the middle latitude region."
"6603162518;7005316058;6507149296;","Local temperature differences in relation to weather parameters",2000,"10.1002/(SICI)1097-0088(200002)20:2<151::AID-JOC460>3.0.CO;2-U","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034036011&doi=10.1002%2f%28SICI%291097-0088%28200002%2920%3a2%3c151%3a%3aAID-JOC460%3e3.0.CO%3b2-U&partnerID=40&md5=9351ad560668dc1e60eaccc5f8fc6478","The objective of this paper is to focus on the influence of clouds and wind on air and road surface temperature variations between different types of local climate environments. The study area covers 160 x 130 km2 and includes 35 field stations in the Swedish Road Weather Information System (RWIS) and two synoptic weather stations. By combining data from the two sources, the spatial and temporal variations in air and road surface temperature have been analysed. In the first part of this paper the theoretical influence of different weather parameters is determined. In the empirical part of the study, a validation of the theoretical result is assessed using temperature and weather data from the study area. The results show that it is possible to calculate the temperature variations in relation to topographical siting and different weather factors. During day-time conditions, the effect of screening from the sun has a significant influence on the road surface temperature, even with cloudiness amounting to 4-6 octas, provided that the solar elevation is high. During night-time, the potential for pooling of cold air is determined by cloud cover and wind speed. When cloudy situations prevail during night-time, neutral stability is dominant resulting in a decrease with increasing altitude for both air and surface temperatures. Road surface temperatures, however, have a lower correlation with altitude than air temperature. The variation in surface temperature decreases with altitude is also larger and has a more even distribution than the air temperature decrease with altitude. Wind speed was not an important factor for the variation in surface temperature decrease with altitude, but insolation from the sun during day-time is one parameter to consider. Copyright (C) 2000 Royal Meteorological Society."
"6603949518;6701473424;","Summer rain episodes in a Mediterranean climate, the case of Israel: Climatological-dynamical analysis",2000,"10.1002/(SICI)1097-0088(200002)20:2<191::AID-JOC464>3.0.CO;2-E","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034070714&doi=10.1002%2f%28SICI%291097-0088%28200002%2920%3a2%3c191%3a%3aAID-JOC464%3e3.0.CO%3b2-E&partnerID=40&md5=e49a5e80efad7c96ed37974001a63c10","Summer in the eastern Mediterranean basin and the Levant region is characterized by an absence of rain. A persistent subsidence aloft, combined with a lower-level cool marine flow, results in a semi permanent inversion which suppresses vertical growth of low clouds, hence inhibiting rain production. However, rain episodes are observed over the northern half of Israel almost every year. This paper examines the regime of summer rainfall in Israel, based on measurements taken over the past 50 years. The rain episodes are found to be rather mild, producing only several millimetres of rainfall, each episode with a mode duration of 1 day. The rain is highly localized. The synoptic conditions during rain episodes are studied from the European Centre of Medium Weather Forecasting (ECMWF) data sets. These show that the prevailing summer synoptic system over the region remains unchanged during rain episodes, that the synoptic-scale subsidence exists throughout, but that the prevailing upper-inversion rises, weakens or even collapses as a result of cooling in the lower-mid-levels, presumably due to the enhanced cold advection within these levels. These findings, together with the observed locality of the rain, suggest that the cause of rain is not a synoptic-scale forcing, but rather a weakening of the rain-suppressive thermodynamic conditions over the Levant region. Copyright (C) 2000 Royal Meteorological Society."
"6602577491;36455675700;6603818654;56257109300;","Planetary-scale tropopause folds in the southern subtropics",2000,"10.1029/1999GL010788","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353476&doi=10.1029%2f1999GL010788&partnerID=40&md5=53ee434099e358bbc974db51376ca231","Daily measurements of tropospheric ozone at La Reunion Island (55 E, 21 S) in July 1998 show that ozone layers are quasi-permanent in the troposphere between 6 and 10 km with values reaching 80 to 100 ppbv. Meridional cross sections of potential vorticity reveal that these layers are related to tropopause folds beneath the subtropical jet. Folding is persistent and extends over a considerable longitude range from mid-Atlantic to mid-Pacific. We suggest that this structure is due to the convergent flow associated to the descent branch of the Hadley circulation during austral winter."
"7402991874;","Spatial and temporal variability of water isotopes in polar precipitation",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034024302&partnerID=40&md5=2fb0019769fc144784930713e8d8d43d","As with 'normal' 1H216O water molecules, the two stable water isotopes 1H218O and 1H2H16O (2H=D=Deuterium) are passed through every part of the water cycle in the atmosphere: water evaporates from ocean and land surfaces, is transported by atmospheric circulation, condenses in clouds and finally forms precipitation falling back to the earth's surface. But since HDO and H218O have a different vapour saturation pressure and molecular diffusivity than H216O, fractionation processes occur during every phase transition of any water sample. The heavier isotopes H218O and HDO become enriched in the liquid or solid phase while the vapour phase becomes more depleted in them. The strength of the fractionation processes highly depends on particular physical parameters, such as temperature and humidity. Numerous geophysical studies have used this dependency to infer information about past climates from measurements of the isotopic composition of precipitation stored in paleowater archives, e.g. in ice cores. In the last several years, atmosphere general circulation models (AGCMs) have been used as a helpful tool for studying water isotopes. Incorporating both H218O and HDO explicitly into the water cycle of the AGCM enables analysing the relationship between the isotopic composition of precipitation and climate variables, such as surface temperatures. Different boundary conditions can be prescribed for the model simulations to gain a better understanding of isotope anomalies caused by different states of the climate. This thesis focuses on the variability of H218O and HDO in precipitation falling on Greenland and Antarctica. Over the last two decades, isotope measurements on several ice cores from both polar regions have revealed new insight in the alternating occurrence of stable climate periods, like the Holocene or the last glacial stage, and fast climatic transition phases between, such as the Younger Dryas. The Hamburg AGCM ECHAM-4 was used to investigate several topics related to these isotope records from Greenland and Antarctica. Simulations for both the present climate and the Last Glacial Maximum (LGM, ~21,000 years ago) were performed to test the reliability of H218O (or HDO) as a proxy for past surface temperatures on Greenland or Antarctica. The model results indicate that a strong change in the seasonal timing of precipitation occurred on Greenland during the LGM and that this change has a significant influence on the mean isotopic composition of ice core samples from this period. Further analyses of the major source regions of water vapour transported to the ice sheets explain some additional changes between the present and LGM climate. So far, little is known about the timing and mechanisms of the transition phase between two stable climate stages. The performed ECHAM-4 sensitivity experiments concentrated on the effects of an meltwater event in the North Atlantic, similar to what might have happened during the Younger Dryas period (~ 16,000 years ago). The simulations revealed that several mechanisms influence the isotopic composition of precipitation during such a meltwater event. A simple interpretation of the isotope signal as a proxy for changed surface temperatures would lead to erroneous estimates of climate changes in many regions of the Northern Hemisphere. Finally, the variability of the isotopic composition of polar precipitation for the climate of the last century is investigated: In an ECHAM-4 simulation of the period 1950-1994, only one-third of the modelled interannual variance is related to simultaneous changes in surface temperatures on Greenland or Antarctica. Several other climate variables, e.g. ocean temperatures of the evaporation areas and/or variability in the water vapour transport to the ice sheets, contribute together a non-negligible part of the fluctuations in the isotope signal in polar precipitation. The imprint of the North Atlantic Oscillation and the El Nino/Southern Oscillation phenomenon is detected in the isotopic composition of precipitation falling in Greenland and Antarctica, respectively. As a summary we conclude from our AGCM isotope experiments, that the isotopic composition of polar precipitation can certainly be used as a proxy for paleoclimatic conditions, but that the interpretation of the isotope signal is neither simple nor straightforward. Especially the strong (spatial) correlation between the isotope signal and surface temperatures on the ice sheets, as it is observed for the present climate, might have been different for past climates."
"7003640407;56033135100;35240796300;","Geological evaluation of multiple general circulation model simulations of late jurassic palaeoclimate",2000,"10.1016/S0031-0182(99)00138-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033969371&doi=10.1016%2fS0031-0182%2899%2900138-8&partnerID=40&md5=dc62a756171cbf9a6f3ac1d36affa190","General circulation models (GCMs) are currently used to predict future global change. However, the robustness of GCMs should be evaluated by their ability to simulate past climate regimes. Their success in 'retrodiction' can then be assessed by reference to the geological record. Geological evidence provides a database that can be used in the estimation of sea surface temperatures, orography and other proxy data useful in palaeoclimatic studies. These data can then be used to refine the prescribed boundary conditions for running GCMs themselves. Results from a series of modelling experiments, run with Late Jurassic (Kimmeridgian) boundary conditions, and using the UK University Global Atmospheric Modelling Programme (UGAMP) GCM and the UK Meteorological Office GCM are presented. Simulations from these two quite independently generated models, although subtly different, confirm a generally warmer Jurassic Earth with arid zones over the Tethys and SW USA, parts of Gondwana dominated by 'monsoonal' systems and convective rainfall generally higher over the oceans than at present. Circum-polar wetlands are also indicated. These results generally conform well to the distributions of known facies in these regions. Modelled cloudiness is also higher in the Jurassic, and although unconfirmed geologically, such conditions would have contributed to greenhouse conditions at high latitudes and could have influenced both terrestrial biomes and marine ecosystems. Using one of the GCMs (UGAMP) we have also investigated the role of orbital parameters for high latitude climate. At times of 'minimum seasonal forcing' (comparable with an orbital geometry affecting the Earth at 115 ka BP) parts of Antarctica could have sustained a modest ice sheet over areas exceeding 1 km elevation, but such modelled sheets would have been ephemeral features and very dynamic in character. (C) 2000 Elsevier Science B.V."
"26643054400;8412522100;7202463361;23479549200;","Denitrification and nitrification in the Arctic stratosphere during the winter of 1996-1997",2000,"10.1029/1999GL011081","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034353469&doi=10.1029%2f1999GL011081&partnerID=40&md5=a07baefe3972335980558a89e5319822","The concentrations of HNO<inf>3</inf>, N<inf>2</inf>O, ozone, and aerosol in the lower stratosphere inside the Arctic vortex were observed by the Improved Limb Atmospheric Spectrometer (ILAS) in the winter of 1996-1997. These data demonstrate that irreversible loss of reactive nitrogen by sedimentation of HNO<inf>3</inf> containing particles (denitrification) at 18-23 km occurred in mid-late February soon after the Arctic vortex cooled below ice saturation temperature (T(ICE)). Denitrification exceeding 40 % was observed only in air masses which experienced temperature below T(ICE). It occurred within 2 days in some of these air masses. Increases in HNO<inf>3</inf> by evaporation of the particles (nitrification) at 13-15 km occurred 0-3 days after denitrification was observed, indicating particle radaii of 5-10 μm or larger. It is likely that these particles were composed of nitric acid trihydrate (NAT) or NAT-coated ice particles, given that the temperatures below 16 km were higher than T(ICE). Continued exposure of air masses below NAT saturation temperature for 1-4 days did not lead to any significant denitrification as long as the temperature did not fall below T(ICE), indicating that possible nucleation of NAT at these temperatures within 4 days did not play a significant role in causing denitrification. There was little change in the average HNO<inf>3</inf> column from February 11 to 28 since HNO<inf>3</inf> decreases at 18-23 km were almost completely offset by increases at 12-17 km."
"6603568514;7102577095;","Implications of microphysics for cloud-radiation parameterizations: Lessons from TOGA COARE",2000,"10.1175/1520-0469(2000)057<0161:IOMFCR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034651225&doi=10.1175%2f1520-0469%282000%29057%3c0161%3aIOMFCR%3e2.0.CO%3b2&partnerID=40&md5=16cf845b8f5a139e54335eb74f6fb765","A single-column model (SCM) and observational data collected during TOGA COARE were used to investigate the sensitivity of model-produced cloud properties and radiative fluxes to the representation of cloud microphysics in the cloud-radiation parameterizations. Four 78-day SCM numerical experiments were conducted for the atmospheric column overlying the COARE Intensive Flux Array. Comparison of model results to both surface and satellite observations revealed that model experiments that calculated cloud properties as a function of cloud liquid water produced more realistic cloud amounts and radiative fluxes.A single-column model (SCM) and observational data collected during TOGA COARE were used to investigate the sensitivity of model-produced cloud properties and radiative fluxes to the representation of cloud microphysics in the cloud-radiation parameterizations. Four 78-day SCM numerical experiments were conducted for the atmospheric column overlying the COARE Intensive Flux Array. Each SCM experiment used a different cloud-radiation parameterization with a different representation of cloud microphysics. All the SCM experiments successfully reproduced most of the observed temporal variability in precipitation, cloud fraction, shortwave and longwave cloud forcing, and downwelling surface shortwave flux. The magnitude and temporal variability of the downward surface longwave flux was overestimated by all the SCM experiments. This bias is probably due to clouds forming too low in the model atmosphere. Time-averaged model results were used to examine the sensitivity of model performance to the differences between the four cloud-radiation parameterization packages. The SCM versions that calculated cloud amount as a function of cloud liquid water, instead of using a relative humidity-based cloud scheme, produced smaller amounts of both low and deep convective clouds. Additionally, larger high (cirrus) cloud emissivities were obtained with interactive cloud liquid water schemes than with the relative humidity-based scheme. Surprisingly, calculating cloud optical properties as a function of cloud liquid water amount, instead of parameterizing them based on temperature, humidity, and pressure, resulted in relatively little change in radiative fluxes. However, model radiative fluxes were sensitive to the specification of the effective cloud droplet radius. Optically thicker low clouds and optically thinner high clouds were produced when an interactive effective cloud droplet radius scheme was used instead of specifying a constant value. Comparison of model results to both surface and satellite observations revealed that model experiments that calculated cloud properties as a function of cloud liquid water produced more realistic cloud amounts and radiative fluxes. The most realistic vertical distribution of clouds was obtained from the SCM experiment that included the most complete representation of cloud microphysics. Due to the limitations of SCMs, the above conclusions are model dependent and need to be tested in a general circulation model."
"56245933700;6701873414;7006204393;","Cloud droplet size distributions in low-level stratiform clouds",2000,"10.1175/1520-0469(2000)057<0295:CDSDIL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034651145&doi=10.1175%2f1520-0469%282000%29057%3c0295%3aCDSDIL%3e2.0.CO%3b2&partnerID=40&md5=516d51a66a1196d42749e7f1e2872f19","A database of stratus cloud droplet (dia<50 μm) size distribution parameter was developed. From the datasets, several parameters are presented, including the total number concentration, effective diameter, mean diameter, standard deviation of the droplet diameter, and liquid water content, as well as the parameters of modified gamma and lognormal distributions. The appropriateness of common assumptions used in remote sensing of cloud droplet size distribution is discussed.A database of stratus cloud droplet (diameter <50 μm) size distribution parameters, derived from in situ data reported in the existing literature, was created, facilitating intercomparison among datasets and quantifying typical values and their variability. From the datasets, which were divided into marine and continental groups, several parameters are presented, including the total number concentration, effective diameter, mean diameter, standard deviation of the droplet diameters about the mean diameter, and liquid water content, as well as the parameters of modified gamma and lognormal distributions. In light of these results, the appropriateness of common assumptions used in remote sensing of cloud droplet size distributions is discussed. For example, vertical profiles of mean diameter, effective diameter, and liquid water content agreed qualitatively with expectations based on the current paradigm of cloud formation. Whereas parcel theory predicts that the standard deviation about the mean diameter should decrease with height, the results illustrated that the standard deviation generally increases with height. A feature common to all marine clouds was their approximately constant total number concentration profiles; however, the total number concentration profiles of continental clouds were highly variable. Without cloud condensation nuclei spectra, classification of clouds into marine and continental groups is based on indirect methods. After reclassification of four sets of measurements in the database, there was a fairly clear dichotomy between marine and continental clouds, but a great deal of variability within each classification. The relevant applications of this study lie in radiative transfer and climate issues, rather than in cloud formation and dynamics. Techniques that invert remotely sensed measurements into cloud droplet size distributions frequently rely on a priori assumptions, such as constant number concentration profiles and constant spectral width. The results of this paper provide a basis for evaluating the sensitivity of these techniques. In particular, there were large enough differences in observed droplet spectral widths to significantly affect remotely sensed determinations of cloud microphysics."
"6603422104;7601318782;7004540083;","Cloud and radiation variations associated with northern midlatitude low and high sea level pressure regimes",2000,"10.1175/1520-0442(2000)013<0312:CARVAW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034074604&doi=10.1175%2f1520-0442%282000%29013%3c0312%3aCARVAW%3e2.0.CO%3b2&partnerID=40&md5=ca90985b296d110ba9df03efb03382b2","A global meteorological dataset, a global satellite dataset, and a radiative transfer model are combined to map the cloud types in low, near-normal, and high sea level pressure regimes in the northern midlatitudes, and to calculate the radiative balance in those regimes. The prominent cloud feature is a background cloud field that is present most of the time and is modulated by changes in dynamic regime. It consists of a low cloud deck, which becomes optically thicker in the warm seasons over ocean and in the cold seasons over land, and a population of optically thin middle-to-high-top clouds that is mostly middle-top in the cold and mostly high-top in the warm seasons. This background cloud field is modulated by the emergence of a population of optically thick high-top clouds in the low pressure regime and by an increase in the optical thickness of the low clouds in the high pressure regime. The top-of-the-atmosphere (TOA) shortwave flux differences between dynamic regimes show that more sunlight is reflected in the low than in the high pressure regime. In January TOA shortwave flux differences between regimes range between 5 and 20 W m-2 and in July between 20 and 50 W m-2, and those differences are manifested as a net excess cooling at the earth's surface. The TOA longwave budget shows more heat trapped in the troposphere in the low pressure than in the high pressure regime. The differences in the TOA outgoing longwave fluxes between the two extreme regimes range in all seasons between 5 and 35 W m-2 and are manifested mostly as an additional warming in the atmospheric column. The TOA total flux differences between the low and high pressure regimes change both sign and magnitude with season; in the winter an excess warming of 5-15 W m-2 is found in the low pressure regime while in all other seasons an excess cooling, which ranges between 10 and 40 W m-2, is found. Preliminary investigations with the Goddard Institute for Space Studies GCM show that changes in midlatitude dynamics with climate can produce significant radiation feedbacks.A global meteorological dataset, a global satellite dataset, and a radiative transfer model are combined to map the cloud types in low, near-normal, and high sea level pressure regimes in the northern midlatitudes, and to calculate the radiative balance in those regimes. The prominent cloud feature is a background cloud field that is present most of the time and is modulated by changes in dynamic regime. It consists of a low cloud deck, which becomes optically thicker in the warm seasons over ocean and in the cold seasons over land, and a population of optically thin middle-to-high-top clouds that is mostly middle-top in the cold and mostly high-top in the warm seasons. This background cloud field is modulated by the emergence of a population of optically thick high-top clouds in the low pressure regime and by an increase in the optical thickness of the low clouds in the high pressure regime. The top-of-the-atmosphere (TOA) shortwave flux differences between dynamic regimes show that more sunlight is reflected in the low than in the high pressure regime. In January TOA shortwave flux differences between regimes range between 5 and 20 W m-2 and in July between 20 and 50 W m-2, and those differences are manifested as a net excess cooling at the earth's surface. The TOA longwave budget shows more heat trapped in the troposphere in the low pressure than in the high pressure regime. The differences in the TOA outgoing longwave fluxes between the two extreme regimes range in all seasons between 5 and 35 W m-2 and are manifested mostly as an additional warming in the atmospheric column. The TOA total flux differences between the low and high pressure regimes change both sign and magnitude with season; in the winter an excess warming of 5-15 W m-2 is found in the low pressure regime while in all other seasons an excess cooling, which ranges between 10 and 40 W m-2, is found. Preliminary investigations with the Goddard Institute for Space Studies GCM show that changes in midlatitude dynamics with climate can produce significant radiation feedbacks."
"7401776640;","Interannual and interdecadal variability in the storm track, cloudiness, and sea surface temperature over the summertime North Pacific",2000,"10.1175/1520-0442(2000)013<0422:IAIVIT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034117792&doi=10.1175%2f1520-0442%282000%29013%3c0422%3aIAIVIT%3e2.0.CO%3b2&partnerID=40&md5=7e87182aa22d3eb9f71806138531471e","Interannual and interdecadal variability in the summertime mean North Pacific storm track is examined in relation to summertime mean sea surface temperature (SST), nimbostratus, and marine stratiform cloudiness (MSC) (stratus, stratocumulus, fog). The storm track is diagnosed by root-mean-squared daily vertical velocity at 500 mb during the summer season (rms ω) obtained from the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis. The cloud and SST data are obtained from surface observations. Year-to-year variations in the storm track exhibit significant coupling to variations in cloudiness and SST across the North Pacific. These correspond to coincident latitudinal shifts in the storm track, SST gradient, and MSC gradient. Moreover, both rms ω and nimbostratus show that the storm track moved equatorward and intensified between 1952 and 1995, consistent with the previously documented upward trend in MSC and downward trend in SST. Lead-lag relationships suggest variability in the storm track has a large role in forcing variability in SST. Boundary layer cloudiness responds to and adds a positive feedback to variability in SST. Weak relationships are observed with the summertime mean large-scale circulation, as diagnosed by sea level pressure. This suggests summertime North Pacific atmosphere-ocean interaction is dominated by local processes operating in the storm track and over the SST gradient, unlike the situation during winter.Interannual and interdecadal variability in the summertime mean North Pacific storm track is examined in relation to summertime mean sea surface temperature (SST), nimbostratus, and marine stratiform cloudiness (MSC) (stratus, stratocumulus, fog). The storm track is diagnosed by root-mean-squared daily vertical velocity at 500 mb during the summer season (rms ω) obtained from the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis. The cloud and SST data are obtained from surface observations. Year-to-year variations in the storm track exhibit significant coupling to variations in cloudiness and SST across the North Pacific. These correspond to coincident latitudinal shifts in the storm track, SST gradient, and MSC gradient. Moreover, both rms ω and nimbostratus show that the storm track moved equatorward and intensified between 1952 and 1995, consistent with the previously documented upward trend in MSC and downward trend in SST. Lead-lag relationships suggest variability in the storm track has a large role in forcing variability in SST. Boundary layer cloudiness responds to and adds a positive feedback to variability in SST. Weak relationships are observed with the summertime mean large-scale circulation, as diagnosed by sea level pressure. This suggests summertime North Pacific atmosphere-ocean interaction is dominated by local processes operating in the storm track and over the SST gradient, unlike the situation during winter."
"7005561168;6603639908;6602276370;6506659449;8571512400;","Feedbacks in a climate system: Cloud, water vapor, and radiation interaction",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033749689&partnerID=40&md5=5710ad3e02be1f596b5ace07fc271dfe","A series of experiments was conducted with the MGO atmosphere-ocean upper mixed layer model to study climate sensitivity to different parametrizations of cloud-radiation interaction and convection under a doubling of CO2 in the atmosphere. The experiments used different assumptions on clouds and cloud optics behavior under warming climate conditions. In the case where both cloud distribution and cloud optics were fixed, global climate warming due to a doubling of CO2 was similar for different convection schemes. When it was assumed that the cloud distribution and cloud optics can change under a doubling of CO2, global climate warming and corresponding changes in a hydrological regime were much dependent on the convection scheme employed. The above differences are due to a vertical cloud rearrangement at low latitudes where convective processes are crucial for global energy redistribution. The increase in cloud optical depth dramatically impacts on climate warming at high latitudes of both hemispheres. Its contribution to climate warming is comparable to that of the earth's surface albedo feedback which is governed by variations in snow-cover and sea-ice extents."
"7407116104;7006393267;","Climate sensitivity to cloud optical properties",2000,"10.3402/tellusb.v52i1.16084","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034108808&doi=10.3402%2ftellusb.v52i1.16084&partnerID=40&md5=299480cb60e2f79dfdd14ff5ca9106b0","A radiative-convective model was developed to investigate the sensitivity of climate to cloud optical properties and the related feedback processes. This model demonstrates that the Earth's surface temperature increases with cloud optical depth when the clouds are very thin but decreases with cloud optical depth when the cloud shortwave (solar) radiative forcing is larger than the cloud longwave (terrestrial) radiative forcing. When clouds are included in the model, the magnitude of the greenhouse effect due to a doubling of the CO2 concentration varies with the cloud optical depth: the thicker the clouds, the weaker the greenhouse warming. In addition, a small variation in the cloud droplet size has a larger impact on the equilibrium state temperature in the lower atmosphere than the warming caused by a doubling of the CO2 concentration: a 2% increase in the average cloud droplet size per degree increase in temperature doubles the warming caused by the doubling of the CO2 concentration. These findings suggest that physically reliable correlations between the cloud droplet size and macrophysical meteorological variables such as temperature, wind and water vapor fields are needed on a global climate scale to assess the climate impact of increases in greenhouse gases."
"7102680152;7006434689;7005069415;7004923073;","Investigation of the interaction between aerosol and clouds at the jungfraujoch (3580 M ASL)",2000,"10.1016/s0021-8502(00)90019-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034269889&doi=10.1016%2fs0021-8502%2800%2990019-3&partnerID=40&md5=1e0c07f1e97c6b2c8fe034ae72d2d1e0",[No abstract available]
"7102300549;6504512037;7103021308;57207261095;35461255500;","Nucleation rates and empirical particle production in bursts",2000,"10.1016/s0021-8502(00)90267-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034270595&doi=10.1016%2fs0021-8502%2800%2990267-2&partnerID=40&md5=1d1fe9c8fab707bcc71acae6035cbdf3",[No abstract available]
"25941200000;","Indirect aerosol forcing by homogeneous and inhomogeneous clouds",2000,"10.1175/1520-0442(2000)013<4042:IAFBHA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034351723&doi=10.1175%2f1520-0442%282000%29013%3c4042%3aIAFBHA%3e2.0.CO%3b2&partnerID=40&md5=d8a12adb4b042983fc3cfb25da0be968","It has been hypothesized that over the past ∼ 200 years, industrial activity has enhanced the number of cloud condensation nuclei (CCN) in the lower atmosphere thereby reducing cloud droplet effective radii re and increasing the albedo of clouds. It is thought that in some regions, cloud albedos have increased so much that they have greatly ameliorated coincidental forcing by increased concentrations of greenhouse gases. The best estimates of this ameliorating effect come from large-scale climate/chemical transport models that assume clouds to be horizontally homogeneous at scales smaller than several hundred kilometers. It is demonstrated here that for a 2-μpm reduction in re, conventional estimates of increased cloud albedo due to more CCN may be too large by up to, and possibly exceeding, 50%. The largest overestimates occur when reductions to re are accompanied by enhancements to both cloud variability and liquid water paths. This is attributed to fundamental differences in the way homogeneous and inhomogeneous clouds transport solar radiation."
"7401441781;7005310521;","High concentrations of greenhouse gases and polar stratospheric clouds: A possible solution to high-latitude faunal migration at the latest Paleocene thermal maximum",2000,"10.1130/0091-7613(2000)28<979:HCOGGA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879887852&doi=10.1130%2f0091-7613%282000%2928%3c979%3aHCOGGA%3e2.0.CO%3b2&partnerID=40&md5=46a328a99f8c5ca7a3a8be11bf43ef3b","High-latitude faunal migrations have been documented during a rapid warming event near the Paleocene-Eocene boundary (the latest Paleocene thermal maximum, LPTM). The migrations are difficult to explain from a climate perspective. Climate along these routes is at present too harsh to support the migrations, and no mechanism has yet proved adequate to explain the past high-latitude warmth required by such migrations. A large negative excursion in the δ 13 C record at the LPTM suggests that a large quantity of CH 4 was released into the atmosphere at this time. High concentrations of atmospheric CH 4 have been linked to the formation of polar stratospheric clouds. We used an atmospheric general circulation model to explore early Cenozoic climate response to the combined effects of high atmospheric CH 4 levels and polar stratospheric clouds, a unique combination of forcing factors in paleoclimate modeling studies. Our interests are in understanding if the climate response to this forcing may explain the high-latitude faunal migrations. Model results indicate that high-latitude winter warming with high methane levels and polar stratospheric clouds is sufficient to facilitate the high-latitude migrations. Temperatures along high-latitude migration routes remained above freezing year-round and thus permitted exchanges of fauna between Asia, North America, and Europe. On the basis of our results, we suggest that other Paleogene migrations may be correlated with LPTM-like events with high concentrations of greenhouse gases and polar stratospheric clouds."
"57193882808;","Cloud microphysics and the tropical climate: Cloud-resolving model perspective",2000,"10.1175/1520-0442(2000)013<2306:CMATTC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034233082&doi=10.1175%2f1520-0442%282000%29013%3c2306%3aCMATTC%3e2.0.CO%3b2&partnerID=40&md5=cfc57bf9315191ad276f6b3121c714f2","This paper discusses the role cloud microphysics play in the tropical climate. It is argued that this problem can best be studied within the context of a cloud-resolving model because of complicated interactions among cloud dynamics, cloud microphysics, radiative processes, and surface processes. Two sets of highly idealized cloud-resolving simulations are discussed. In each set, the simulations differ only in the parameters applied in the representation of cloud microphysics. The simulations are run until quasi-equilibrium between sinks and sources of moisture and energy is achieved. The comparisons between simulations applying dramatically different parameters exposes the effects of cloud microphysics on the mean state of the tropical atmosphere and on the tropical climate. The first set considers large-scale flow driven by sea surface temperature gradients and prescribed radiative cooling. The cloud microphysics appears to have minor effects on the large-scale flow as well as temperature and moisture profiles within ascending branches featuring deep convection. The second set considers tropical convection over a shallow isothermal layer of water ('swamp ocean') applying an interactive radiation transfer model. The sea surface temperature beneath each column of the atmospheric model changes according to the local budget of surface heat and radiative fluxes. For simplicity, equatorial equinox conditions, no diurnal cycle, and a zero zenith angle are assumed. Changes in parameters in cloud microphysics appear to have a dramatic impact on the quasi-equilibrium ocean temperature that ranges from about 37°-38°C in the simulation assuming large cloud and precipitation particles to 32°-35°C in the simulation assuming small particles. These highly idealized simulations suggest that the main effect of cloud microphysics is not on atmospheric processes and dynamics but rather on the ocean surface. If this suggestion is realistic, effects of cloud microphysics will be very difficult to quantify in the ocean-atmosphere system because of the much longer timescales associated with ocean dynamics.This paper discusses the role cloud microphysics play in the tropical climate. It is argued that this problem can best be studied within the context of a cloud-resolving model because of complicated interactions among cloud dynamics, cloud microphysics, radiative processes, and surface processes. Two sets of highly idealized cloud-resolving simulations are discussed. In each set, the simulations differ only in the parameters applied in the representation of cloud microphysics. The simulations are run until quasi-equilibrium between sinks and sources of moisture and energy is achieved. The comparisons between simulations applying dramatically different parameters exposes the effects of cloud microphysics on the mean state of the tropical atmosphere and on the tropical climate. The first set considers large-scale flow driven by sea surface temperature gradients and prescribed radiative cooling. The cloud microphysics appears to have minor effects on the large-scale flow as well as temperature and moisture profiles within ascending branches featuring deep convection. The second set considers tropical convection over a shallow isothermal layer of water ('swamp ocean') applying an interactive radiation transfer model. The sea surface temperature beneath each column of the atmospheric model changes according to the local budget of surface heat and radiative fluxes. For simplicity, equatorial equinox conditions, no diurnal cycle, and a zero zenith angle are assumed. Changes in parameters in cloud microphysics appear to have a dramatic impact on the quasi-equilibrium ocean temperature that ranges from about 37°-38°C in the simulation assuming large cloud and precipitation particles to 32°-35°C in the simulation assuming small particles. These highly idealized simulations suggest that the main effect of cloud microphysics is not on atmospheric processes and dynamics but rather on the ocean surface. If this suggestion is realistic, effects of cloud microphysics will be very difficult to quantify in the ocean-atmosphere system because of the much longer timescales associated with ocean dynamics."
"7006573844;7006792445;24560382000;6701858523;","Dimethylsulfide production variations over the past 200 k.y. in the equatorial Atlantic: A first estimate",2000,"10.1130/0091-7613(2000)028<0499:dpvotp>2.3.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086353000&doi=10.1130%2f0091-7613%282000%29028%3c0499%3adpvotp%3e2.3.co%3b2&partnerID=40&md5=751410a61a4a033845ddf6e3426d85f7","Dimethylsulfide (DMS) released from phytoplankton produces cloud condensation nuclei in the marine troposphere, thereby providing a climate-regulating mechanism by increasing cloud albedo. A 200-k.y.-long sedimentary record from the equatorial Atlantic of DMS-producing phytoplankton suggests that DMS production increased during the glacial stages, thus potentially working to further cool the glacial world. Important factors limiting the operation of this possible feedback mechanism for planetary cooling may be the strength of trade winds and the availability of fine, iron-rich dust needed to fertilize growth of DMS producers."
"7102300549;57203260116;7004198777;","Aerosol nucleation and mixing in the upper troposphere",2000,"10.1016/s0021-8502(00)90581-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034271011&doi=10.1016%2fs0021-8502%2800%2990581-0&partnerID=40&md5=562ee9ee2250932efb51fae157690344",[No abstract available]
"35449990500;","Atmospheric aerosol measurements at Mace Head, Ireland",2000,"10.1016/s0021-8502(00)90591-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034270415&doi=10.1016%2fs0021-8502%2800%2990591-3&partnerID=40&md5=694b82ec21c390f9010a48a5572e4577",[No abstract available]
"57193132723;7403174207;","The temperature dependence of the liquid water path of low clouds in the southern great plains",2000,"10.1175/1520-0442(2000)013<3465:TTDOTL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034298220&doi=10.1175%2f1520-0442%282000%29013%3c3465%3aTTDOTL%3e2.0.CO%3b2&partnerID=40&md5=6e6bac384b062cec27076bb2cb2ced8d","Satellite observations of low-level clouds have challenged the idea that increasing liquid water content with temperature combined with constant physical thickness will lead to a negative cloud optics feedback in a decadal climate change. The reasons for the satellite results are explored using 4 yr of surface remote sensing data from the Atmospheric Radiation Measurement Program Cloud and Radiation Testbed site in the southern Great Plains of the United States. It is found that low-cloud liquid water path is approximately invariant with temperature in winter but decrease strongly with temperature in summer, consistent with satellite inferences at this latitude. This behavior occurs because liquid water content shows no detectable temperature dependence while cloud physical thickness decreases with warming. Thinning of clouds with warming is observed on seasonal, synoptic, and diurnal timescales; it is most obvious in the warm sectors of baroclinic waves. Although cloud top is observed to slightly descend with warming, the primary cause of thinning is the ascent of cloud base due to the reduction in surface relative humidity and the concomitant increase in the lifting condensation level of surface air. Low-cloud liquid water path is not observed to be a continuous function of temperature. Rather, the behavior observed is best explained as a transition in the frequency of occurrence of different boundary layer types. At cold temperatures, a mixture of stratified and convective boundary layers is observed, leading to a broad distribution of liquid water path values, while at warm temperatures, only convective boundary layers with small liquid water paths, some of them decoupled, are observed. Our results, combined with the earlier satellite inferences, suggest a reexamination of the commonly quoted 1.5°C lower limit for the equilibrium global climate sensitivity to a doubling of CO2, which is based on models in which liquid water increases with temperature and cloud physical thickness is constant.Satellite observations of low-level clouds have challenged the idea that increasing liquid water content with temperature combined with constant physical thickness will lead to a negative cloud optics feedback in a decadal climate change. The reasons for the satellite results are explored using 4 yr of surface remote sensing data from the Atmospheric Radiation Measurement Program Cloud and Radiation Testbed site in the southern Great Plains of the United States. It is found that low-cloud liquid water path is approximately invariant with temperature in winter but decreases strongly with temperature in summer, consistent with satellite inferences at this latitude. This behavior occurs because liquid water content shows no detectable temperature dependence while cloud physical thickness decreases with warming. Thinning of clouds with warming is observed on seasonal, synoptic, and diurnal timescales; it is most obvious in the warm sectors of baroclinic waves. Although cloud top is observed to slightly descend with warming, the primary cause of thinning is the ascent of cloud base due to the reduction in surface relative humidity and the concomitant increase in the lifting condensation level of surface air. Low-cloud liquid water path is not observed to be a continuous function of temperature. Rather, the behavior observed is best explained as a transition in the frequency of occurrence of different boundary layer types. At cold temperatures, a mixture of stratified and convective boundary layers is, observed, leading to a broad distribution of liquid water path values, while at warm temperatures, only convective boundary layers with small liquid water paths, some of them decoupled, are observed. Our results, combined with the earlier satellite inferences, suggest a reexamination of the commonly quoted 1.5°C lower limit for the equilibrium global climate sensitivity to a doubling of CO2, which is based on models in which liquid water increases with temperature and cloud physical thickness is constant."
"6701608776;7101945366;","Midlatitude frontal clouds: GCM-scale modeling implications",2000,"10.1175/1520-0442(2000)013<2729:MFCGSM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253093&doi=10.1175%2f1520-0442%282000%29013%3c2729%3aMFCGSM%3e2.0.CO%3b2&partnerID=40&md5=492ba47b41667c1bb83831ee698d6137","The importance of subgrid-scale processes for the simulation of midlatitude frontal clouds by global models is investigated. The case chosen is a frontal cloud associated with a cool change crossing the southern Australian coastline between 17 and 19 November 1984. The Commonwealth Scientific and Industrial Research Organisation limited-area model, Division of Atmospheric Research Limited-Area Model, was run at horizontal resolutions of 30 and 300 km, and the results of the 30-km simulation were then averaged to 300-km resolution. Comparisons and evaluations of the simulations showed that the 300-km simulation failed to develop the frontal clouds. Comparison with the 30-km simulation averaged to 300 km showed the importance of the subgrid-scale vertical motions for this cloud development. In particular, it is found that the covariance of the subgrid-scale terms, although of smaller magnitude when compared with the larger-scale terms, needs to be parameterized to capture correctly the frontal cloud development. It is suggested that parameterization of the subgrid-scale dynamical forcing is important for the correct cloud development in general circulation models.The importance of subgrid-scale processes for the simulation of midlatitude frontal clouds by global models is investigated. The case chosen is a frontal cloud associated with a cool change crossing the southern Australian coastline between 17 and 19 November 1984. The Commonwealth Scientific and Industrial Research Organisation limited-area model, Division of Atmospheric Research Limited-Area Model, was run at horizontal resolutions of 30 and 300 km, and the results of the 30-km simulation were then averaged to 300-km resolution. Comparisons and evaluations of the simulations showed that the 300-km simulation failed to develop the frontal clouds. Comparison with the 30-km simulation averaged to 300 km showed the importance of the subgrid-scale vertical motions for this cloud development. In particular, it is found that the covariance of the subgrid-scale terms, although of smaller magnitude when compared with the larger-scale terms, needs to be parameterized to capture correctly the frontal cloud development. It is suggested that parameterization of the subgrid-scale dynamical forcing is important for the correct cloud development in general circulation models."
"16637291100;6603746990;","Cloud particle phase determination with the AVHRR",2000,"10.1175/1520-0450-39.10.1797","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034518104&doi=10.1175%2f1520-0450-39.10.1797&partnerID=40&md5=076b93281a0b369735a41990b3ff502f","An accurate determination of cloud particle phase is required for the retrieval of other cloud properties from satellite and for radiative flux calculations in climate models. The physical principles underlying phase determination using the advanced very high resolution radiometer (AVHRR) satellite sensor are described for daytime and nighttime, cold cloud and warm cloud conditions. It is demonstrated that the spectral properties of cloud particles provide necessary, but not sufficient, information for phase determination, because the relationship between the cloud and surface temperatures is also important. Algorithms based on these principles are presented and tested. Validation with lidar and aircraft data from two Arctic field experiments shows the procedures to be accurate in identifying the phase of homogeneous water and ice clouds, though optically thin, mixed-phase, and multilayer clouds are problematic."
"8299300000;","Parameterization of nonconvective condensation for low-resolution climate models: Comparison of diagnostic schemes for fractional cloud cover and cloud water content",2000,"10.2151/jmsj1965.78.1_1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0040786275&doi=10.2151%2fjmsj1965.78.1_1&partnerID=40&md5=205a5e5ba398321a34e6d015e01f957f","Nonconvective partial condensation in a coarse grid box of low-resolution climate models has been parameterized in terms of a heavy-tailed probability density function of ""liquid water"" relative humidity. In our diagnostic scheme, temperatures of the cloud and clear-air parts in a model grid box are assumed to be equal, so that a strong buoyant force does not act on the clouds. When the present diagnostic scheme is adopted, nonconvective stratiform clouds begin to form at grid-averaged relative humidities lower than 70 %. Numerical experiments on the baroclinic wave growth in a midlatitude β-plane channel have shown that our scheme brings earlier occurrence and larger amount of precipitation than the ""all-or-nothing"" scheme or the Le Treut-Li (1991) scheme. Moreover, it has been indicated that our scheme produces nonconvective precipitation not only along the warm and cold frontal regions, but also in the warm sector of an occluding extratropical cyclone."
"7004462010;6602272898;","Radiative forcing due to clouds and aerosol",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033668280&partnerID=40&md5=8076f307fb4a2c913713dd00beb3b31e","Radiative forcing of stratiform clouds has been studied on the basis of complex measurements of spectral and integral hemispheric fluxes of shortwave radiation in a cloudy and clear-sky atmosphere. Calculations have been made of cloud radiative forcing as a function of latitude, optical depth, solar zenith angle, and also for absorbing and scattering aerosols over a city and over a rural area in the case when strong duststorms take place. A comparison between measured and calculated values of cloud radiative forcing has been made. It is shown that clouds play an important role in shortwave radiation absorption not only in the near infrared spectrum but also in the visible region. It is noted that this effect has to be included in the radiation block of atmospheric general circulation and climate models."
"8666820400;7007115297;7006084942;","The comparison of modelled surface level sulfur species concentrations from COSAM with observations",2000,"10.1016/s0021-8502(00)90153-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034269791&doi=10.1016%2fs0021-8502%2800%2990153-8&partnerID=40&md5=8e0a351acdf31483db40e85849745e5d",[No abstract available]
"55976016100;6603331306;7004518227;","Climate hypersensitivity to solar forcing?",2000,"10.1007/s00585-000-0583-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0005555090&doi=10.1007%2fs00585-000-0583-z&partnerID=40&md5=d12ef2476bb2b89b2a2cb3cc78b8124a","We compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO2, solar total irradiance (Stot) and solar UV (SUV). The response is largest in the SUV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak response from global-columnar radiative loading by increases in CO2 or Stot. The hypersensitive response of the climate system to solar UV forcing is caused by strongly coupled feedback involving vertical static stability, tropical thick cirrus ice clouds and stratospheric ozone. This mechanism offers a plausible explanation of the apparent hypersensitivity of climate to solar forcing, as suggested by analyses of recent climatic records. The model hypersensitivity strongly depends on climate parameters, especially cloud radiative properties, but is effective for arguably realistic values of these parameters. The proposed solar forcing mechanism should be further confirmed using other models (e.g., general circulation models) that may better capture radiative and dynamical couplings of the troposphere and stratosphere."
"7202162685;16185051500;35468686100;7202208382;7006783796;7007108728;7402584913;6701764148;6602991061;57119767800;7202185413;22975069200;15032788000;7402565763;6603746990;7006698304;7401539646;8363388700;7005305477;35567153700;6603800142;6603585457;7402049334;6603989070;7006239404;15054885700;7007114588;","FIRE arctic clouds experiment",2000,"10.1175/1520-0477(2000)081<0005:FACE>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0002884692&doi=10.1175%2f1520-0477%282000%29081%3c0005%3aFACE%3e2.3.CO%3b2&partnerID=40&md5=4b5cf4362cbad90679cb580622e6fa5a","An overview is given of the First ISCCP Regional Experiment Arctic Clouds Experiment that was conducted during April-July 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic clouds on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influences the evolution of boundary layer clouds. The observations will be used to evaluate and improve climate model parameterizations of cloud and radiation processes, satellite remote sensing of cloud and surface characteristics, and understanding of cloud-radiation feedbacks in the Arctic. The experiment utilized four research aircraft that flew over surface-based observational sites in the Arctic Ocean and at Barrow, Alaska. This paper describes the programmatic and scientific objectives of the project, the experimental design (including research platforms and instrumentation), the conditions that were encountered during the field experiment, and some highlights of preliminary observations, modeling, and satellite remote sensing studies."
"6701366594;57196396429;6505574439;7103010852;55466977400;7404209127;7004893330;35494722400;7003723817;6504348689;7102180306;6603860837;7006813055;7004149770;7102432430;7004034323;7003826074;6602734863;6603801190;6602836578;7102708039;","Scientific background for CLOUDS - a cloud and radiation monitoring satellite",2000,"10.1117/12.413878","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034542260&doi=10.1117%2f12.413878&partnerID=40&md5=ea89c69ef047a45a9da2ecb17683b1c7","CLOUDS is a project supported by the European Union, conducted by 12 European partners (7 scientific institutes and 5 industrial companies), also cooperating with NOAA/ETL. It is the mission study of a monitoring satellite to perform measurements necessary to describe cloud-radiation interaction in operational models for climate and weather prediction. The `monitoring' objective implies relative large instruments swath as to provide a relatively frequent global coverage: 24 h for a number of measurements, 48 h for the majority. The products resolution for weather prediction is about 30 km; for climate applications, the required accuracy is achieved after averaging over 100 km and 1 week. The instrument resolution ranges between 5 and 10 km for most channels, up to 40 km for some. The required short observing cycle prevents using active instruments. Instead, use is made of (i) passive radiometry over a widest part of the e.m. spectrum (UV, VIS, NIR, TIR, FIR, Sub-mm and MW); (ii) different polarizations to determine 2-3 Stokes parameters in a number of channels; (iii) fore- and aft-viewing for all channels, and multi-angle viewing for one channel. CLOUDS includes six instruments, all conical scanning: (i) a package of four optical, with channels from UV to FIR for cloud surface properties, aerosol and ERB; (ii) a Sub-mm radiometer for cloud ice and water vapour; (iii) a MW radiometer for liquid water and precipitation The satellite mass is estimated below 1000 kg. The orbit is sun-synchronous 10 h LST, 840 km altitude."
"55109904700;7202208382;7005212820;","Diurnal variability of the hydrologic cycle and radiative fluxes: Comparisons between observations and a GCM",2000,"10.1175/1520-0442(2000)013<4159:DVOTHC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034477066&doi=10.1175%2f1520-0442%282000%29013%3c4159%3aDVOTHC%3e2.0.CO%3b2&partnerID=40&md5=c8fc87c5ae95b44f6872d186b30e5189","The simulated diurnal cycle is in many ways an ideal test bed for new physical parameterizations. The purpose of this paper is to compare observations from the Tropical Rainfall Measurement Mission, the Earth Radiation Budget Experiment, the International Satellite Cloud Climatology Project, the Clouds and the Earth's Radiant Energy System Experiment, and the Anglo-Brazilian Amazonian Climate Observation Study with the diurnal variability of the Amazonian hydrologic cycle and radiative energy budget as simulated by the Colorado State University general circulation model, and to evaluate improvements and deficiencies of the model physics. The model uses a prognostic cumulus kinetic energy (CKE) to relax the quasi-equilibrium closure of the Arakawa-Schubert cumulus parameterization. A parameter, α, is used to relate the CKE to the cumulus mass flux. This parameter is expected to vary with cloud depth, mean shear, and the level of convective activity, but up to now a single constant value for all cloud types has been used. The results of the present study show clearly that this approach cannot yield realistic simulations of both the diurnal cycle and the monthly mean climate state. Improved results are obtained using a version of the model in which α is permitted to vary with cloud depth."
"7410084319;","The impact of a physically based microphysical scheme on the climate simulation of the Meteorological Office unified model",2000,"10.1256/smsqj.56504","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034045914&doi=10.1256%2fsmsqj.56504&partnerID=40&md5=752b2f35ebce3f988069b3d2dc066ab0","The predictions of two, large-scale precipitation schemes for a general-circulation model are compared within a development version of the Meteorological Office's climate model. One scheme contains a prognostic ice content and a representation of mixed-phase microphysical processes, whereas the second scheme is a diagnostic scheme where condensate is partitioned into liquid and ice as a function of temperature. Results show that, although the overall near-surface conditions are similar, significant differences occur in the structure of clouds predicted by the two schemes. The total precipitation rate is similar, but the microphysical scheme has less convective activity than the temperature-partition scheme, because of the different subgrid nature of the schemes. Layer-cloud amounts are changed due to both changes in condensate and changes in its diagnosis. More ice is predicted by the microphysical scheme, mainly as a result of reduced fall speeds of ice particles. This shows the need for global measurement methods of ice-water content to be developed."
"36908503100;","Are cosmic rays influencing oceanic cloud coverage - Or is it only El Nino?",2000,"10.1023/a:1005672825112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033771833&doi=10.1023%2fa%3a1005672825112&partnerID=40&md5=138e0597f764b08e6be97ab639000513","The monthly average (C2) cloud coverage data produced by the International Satellite Cloud Climatology Project (ISCCP) for the period of July 1986-June 1991 show strong global and regional cloud coverage variations associated with the El Nino of 1986-1987. The Pacific Ocean, in particular, shows strong regional variations in cloud coverage. These agree well with contemporaneous satellite observations of broadband shortwave infrared cloud forcing measured by the Earth Radiation Budget Experiment. Svensmark and Friis-Christensen (1997) noted a similarity between the shape of the time series curve of average cloud coverage fraction for mid- to low-latitude ocean-areas and the time series curve of cosmic ray flux intensity. They proposed a causal relationship - A 'missing link' for solar cycle influence on Earth climate. Further spatial and temporal analysis of the same ISCCP C2 data in this paper indicates that the cloud coverage variation patterns are those to be expected for the atmospheric circulation changes characteristic of El Nino, weakening the case for cosmic rays as a climatic forcing factor."
"7005056279;56213029000;7201457242;7404678955;7410298977;","A new boundary layer mixing scheme. Part I: Scheme description and single-column model tests",2000,"10.1175/1520-0493(2000)128<3187:ANBLMS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034276838&doi=10.1175%2f1520-0493%282000%29128%3c3187%3aANBLMS%3e2.0.CO%3b2&partnerID=40&md5=9a634021630549d6af974445eb385772","A new boundary layer turbulent mixing scheme has been developed for use in the UKMO weather forecasting and climate prediction models. This includes a representation of nonlocal mixing (driven by both surface fluxes and cloud-top processes) in unstable layers, either coupled to or decoupled from the surface, and an explicit entrainment parameterization. The scheme is formulated in moist conserved variables so that it can treat both dry and cloudy layers. Details of the scheme and examples of its performance in single-column model tests are presented.A new boundary layer turbulent mixing scheme has been developed for use in the UKMO weather forecasting and climate prediction models. This includes a representation of nonlocal mixing (driven by both surface fluxes and cloud-top processes) in unstable layers, either coupled to or decoupled from the surface, and an explicit entrainment parameterization. The scheme is formulated in moist conserved variables so that it can treat both dry and cloudy layers. Details of the scheme and examples of its performance in single-column model tests are presented."
"55205365700;7006738324;","An experimental technique for testing the validity of cumulus cloud parameterizations for longwave radiation calculations",2000,"10.1175/1520-0450(2000)039<1147:AETFTT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033831961&doi=10.1175%2f1520-0450%282000%29039%3c1147%3aAETFTT%3e2.0.CO%3b2&partnerID=40&md5=6ecb87e8c3165995403055aa55abc59a","Cumulus cloud bulk geometry, size, and spatial distributions have long been recognized as important factors for longwave radiative transfer under broken cloud conditions. Most current climate models, however, still ignore these factors and estimate the effects of broken cumulus clouds as the cloud amount-weighted average of clear and black-cloud overcast conditions, that is, the black plate approximation. Although several groups have adopted the simplicity of the black plate approximation and extended it to include the effects of cloud geometry, cloud size, and spatial distributions by defining an effective cloud fraction, the validity of these parameterizations has long been assumed because of inadequate measurements of the instantaneous atmospheric radiative properties. Now ground-based measurements at the Atmospheric Radiation Measurement Program southern Great Plains Cloud and Radiation Test Bed site allow the derivation of the effective cloud fraction, absolute cloud fraction, cloud aspect ratio, and many other variables characterizing cumulus clouds. Using an empirically determined sampling period of 10 min, several different parameterizations for effective cumulus cloud fraction were tested by comparing effective amounts derived from hemispheric flux observations with values predicted by the parameterizations. Within the range of data and among the models tested, the better results were obtained with the cuboidal model with exponential cloud size and spatial distributions, the random cylinder model, the regular cuboidal model, and the shifted-periodic array cuboidal model. However, there are few cases in the range of greatest sensitivity where model comparisons demonstrate larger disparity."
"7005513582;57127513900;7006705919;7102913661;57198879470;","Radiative forcing due to sulfate aerosols from simulations with the National Center for Atmospheric Research Community Climate Model, Version 3",2000,"10.1029/1999JD900495","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033792612&doi=10.1029%2f1999JD900495&partnerID=40&md5=a0b7d6baa26912032cbe49efa37561f1","The direct and indirect radiative forcing due to sulfate aerosols is calculated in a version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM3). This model includes a sulfur chemistry model and predicts the mass of sulfate. New optical properties are presented that account for the hygroscopic growth effects on both extinction optical depth and asymmetry parameter. These new properties enhance the sulfate direct forcing for relative humidities above 90% compared to previous results. The global annual mean forcing is -0.56 W m-2. The forcing due to the indirect cloud albedo effect is studied using four different methods to relate cloud drop number concentration to sulfate mass. One method assumes the presence of background aerosols that can also act as a source of cloud condensation nuclei. This effect reduces the magnitude of the indirect effect by 40% to -0.4 W m-2. This sensitivity study indicates the importance of the presence of other aerosols that can nucleate cloud drops. The seasonal cycle of the indirect effect is different from that of the direct effect, as the maximum of the indirect effect occurs in the Northern Hemisphere springtime, while that of the direct effect is largest in the Northern Hemisphere summer. The four different methods of accounting for the indirect effect result in a large uncertainty in the global annual mean net forcing due to sulfates and greenhouse gases, 0.05 to 1.42 W m-2. It is argued that a less empirical and more physically based approach is required to account for the indirect effect in climate models. Copyright 2000 by the American Geophysical Union."
"7004282006;6701333544;","Extremal climatic states simulated by a 2-dimensional model. Part I: Sensitivity of the model and present state",2000,"10.3402/tellusa.v52i4.12272","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033865460&doi=10.3402%2ftellusa.v52i4.12272&partnerID=40&md5=23d63d75e5e05a344d29117296b11acd","The criterion, based on the thermodynamics theory, that the climatic system tends to extremize some function has suggested several studies. In particular, special attention has been devoted to the possibility that the climate reaches an extremal rate of planetary entropy production. Due to both radiative and material effects contribute to total planetary entropy production, climatic simulations obtained at the extremal rates of total, radiative or material entropy production appear to be of interest in order to elucidate which of the three extremal assumptions behaves more similar to current data. In the present paper, these results have been obtained by applying a 2-dimensional (2-Dim) horizontal energy balance box-model, with a few independent variables (surface temperature, cloud-cover and material heat fluxes). In addition, climatic simulations for current conditions by assuming a fixed cloud-cover have been obtained. Finally, sensitivity analyses for both variable and fixed cloud models have been carried out."
"7404678955;7201457242;56213029000;7005056279;7410298977;","A new boundary layer mixing scheme part II: Tests in climate and mesoscale models",2000,"10.1175/1520-0493(2000)128<3200:ANBLMS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034277323&doi=10.1175%2f1520-0493%282000%29128%3c3200%3aANBLMS%3e2.0.CO%3b2&partnerID=40&md5=52c081e392f382d1e565632faf422295","A new turbulent mixing scheme, described in Part I of this paper, is tested in the climate and mesoscale configurations of the U.K. Met. Office's Unified Model (UM). In climate configuration, the scheme is implemented along with increased vertical resolution below 700 hPa (the same as that in the mesoscale model), in order to allow the different boundary layer types and processes to be identified and treated properly. In both configurations, the new boundary layer (PBL-N) mixing scheme produces some improvement over the current boundary layer (PBL-C) scheme. The PBL-N scheme is able to diagnose different boundary layer types that appear to be consistent with the observed conditions, and the boundary layer structure is improved in comparison with observations. In the climate model, the boundary layer and cloud structure in the semipermanent stratocumulus regions of the eastern subtropical oceans are noticeably improved with the PBL-N scheme. The deepening and decoupling of the boundary layer toward the trade cumulus regime is also simulated more realistically. However, the cloud amounts in the stratocumulus regions, which were underestimated with the PBL-C scheme, are reduced further when the PBL-N scheme is included. Tests of the PBL-N scheme in the UM single-column model and in a development version of the UM, where the dynamics, time stepping, and vertical grid are different from the standard version, both show that realistic stratocumulus cloud amounts can be achieved. Thus, it is thought that the performance of the PBL-N scheme in the standard UM may be being limited by other aspects of that model. In the mesoscale model, improvements in the simulation of a convective case are achieved with the PBL-N scheme through reductions in layer cloud amount, while the simulation of a stratocumulus case is improved through better representation of the cloud and boundary layer structure. Other mesoscale model case studies show that there is a consistent improvement in fog probabilities and forecasts of cloud-base height. The root-mean-square errors in screen-level temperature are also reduced slightly. The weak daytime bias in wind strength is improved greatly through a systematic increase in the 10-m wind speed in unstable conditions. As a result of these trials, the scheme has been implemented operationally in the mesoscale model.A new turbulent mixing scheme, described in Part I of this paper, is tested in the climate and mesoscale configurations of the U.K. Met. Office's Unified Model (UM). In climate configuration, the scheme is implemented along with increased vertical resolution below 700 hPa (the same as that in the mesoscale model), in order to allow the different boundary layer types and processes to be identified and treated properly. In both configurations, the new boundary layer (PBL-N) mixing scheme produces some improvement over the current boundary layer (PBL-C) scheme. The PBL-N scheme is able to diagnose different boundary layer types that appear to be consistent with the observed conditions, and the boundary layer structure is improved in comparison with observations. In the climate model, the boundary layer and cloud structure in the semipermanent stratocumulus regions of the eastern subtropical oceans are noticeably improved with the PBL-N scheme. The deepening and decoupling of the boundary layer toward the trade cumulus regime is also simulated more realistically. However, the cloud amounts in the stratocumulus regions, which were underestimated with the PBL-C scheme, are reduced further when the PBL-N scheme is included. Tests of the PBL-N scheme in the UM single-column model and in a development version of the UM, where the dynamics, time stepping, and vertical grid are different from the standard version, both show that realistic stratocumulus cloud amounts can be achieved. Thus, it is thought that the performance of the PBL-N scheme in the standard UM may be being limited by other aspects of that model. In the mesoscale model, improvements in the simulation of a convective case are achieved with the PBL-N scheme through reductions in layer cloud amount, while the simulation of a stratocumulus case is improved through better representation of the cloud and boundary layer structure. Other mesoscale model case studies show that there is consistent improvement in fog probabilities and forecasts of cloud-base height. The root-mean-square errors in screen-level temperature are also reduced slightly. The weak daytime bias in wind strength is improved greatly through a systematic increase in the 10-m wind speed in unstable conditions. As a result of these trials, the scheme has been implemented operationally in the mesoscale model."
"7004061048;","Entrainment rate, cloud fraction, and liquid water path of PBL stratocumulus clouds",2000,"10.1175/1520-0469(2000)057<3627:ERCFAL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034318974&doi=10.1175%2f1520-0469%282000%29057%3c3627%3aERCFAL%3e2.0.CO%3b2&partnerID=40&md5=928d7c9d5a82a9429ed3afa353611900","The large eddy simulation technique is used to search for key factors in determining the entrainment rate, cloud fraction, and liquid water path in the stratocumulus-topped boundary layer (STBL), with the goal of developing simple schemes of calculating these important quantities in climate models. In this study an entrainment rate formula is proposed where the entrainment rate is determined by four variables - total jump of the liquid water potential temperature across the entrainment zone, surface heat flux, net radiative flux away from the top of the STBL, and liquid water path. This study also shows that buoyancy reversal, measured here as the ratio between the equivalent potential temperature jump and the total moisture jump across the cloud top, plays a major role in reducing the simulated cloud amount, both cloud fraction and liquid water path. For cases where no buoyancy reversal occurs, the simulated cloud fraction remains 100% and the liquid water path depends solely on the cloud height. This study raises an interesting feature about what controls the entrainment rate of the STBL. The two cases with a larger surface heat flux studied here show that the net impact of surface heating on the entrainment rate could be negligible if surface heating also leads to enhanced cloud-top evaporation; enhanced evaporation then results in smaller cloud amount and hence smaller radiative forcing for entrainment. Since larger surface heat flux always significantly increases the layer-averaged buoyancy flux and the turbulence intensity, the entrainment rate of the STBL for a given inversion strength is therefore not always directly proportional to the layer-averaged buoyancy flux or to the turbulence intensity.The large eddy simulation technique is used to search for key factors in determining the entrainment rate, cloud fraction, and liquid water path in the stratocumulus-topped boundary layer (STBL), with the goal of developing simple schemes of calculating these important quantities in climate models. In this study an entrainment rate formula is proposed where the entrainment rate is determined by four variables-total jump of the liquid water potential temperature across the entrainment zone, surface heat flux, net radiative flux away from the top of the STBL, and liquid water path. This study also shows that buoyancy reversal, measured here as the ratio between the equivalent potential temperature jump and the total moisture jump across the cloud top, plays a major role in reducing the simulated cloud amount, both cloud fraction and liquid water path. For cases where no buoyancy reversal occurs, the simulated cloud fraction remains 100% and the liquid water path depends solely on the cloud height. This study raises an interesting feature about what controls the entrainment rate of the STBL. The two cases with a larger surface heat flux studied here show that the net impact of surface heating on the entrainment rate could be negligible if surface heating also leads to enhanced cloud-top evaporation; enhanced evaporation then results in smaller cloud amount and hence smaller radiative forcing for entrainment. Since larger surface heat flux always significantly increases the layer-averaged buoyancy flux and the turbulence intensity, the entrainment rate of the STBL for a given inversion strength is therefore not always directly proportional to the layer-averaged buoyancy flux or to the turbulence intensity."
"55896920900;7004885872;6603892183;56128808100;6701599239;6701596624;7006577245;56706602500;7202408184;7004838931;","An overview of the ACE-2 CLOUDYCOLUMN closure experiment",2000,"10.1034/j.1600-0889.2000.00047.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034070781&doi=10.1034%2fj.1600-0889.2000.00047.x&partnerID=40&md5=70c819e0e0d4599c6461b05d7ef74967","CLOUDYCOLUMN is one of the 6 ACE-2 projects which took place in June-July 1997, between Portugal and the Canary Islands. It was specifically dedicated to the study of changes of cloud radiative properties resulting from changes in the properties of those aerosols which act as cloud condensation nuclei. This process is also refered to as the aerosol indirect effect on climate. CLOUDYCOLUMN is focused on the contribution of stratocumulus clouds to that process. In addition to the basic aerosol measurements performed at the ground stations of the ACE-2 project, 5 instrumented aircraft carried out in situ characterization of aerosol physical, chemical and nucleation properties and cloud dynamical and microphysical properties. Cloud radiative properties were also measured remotely with radiometers and a lidar. 11 case studies have been documented, from pure marine to significantly polluted air masses. The simultaneity of the measurements with the multi-aircraft approach provides a unique data set for closure experiments on the aerosol indirect effect. In particular CLOUDYCOLUMN provided the 1st experimental evidence of the existence of the indirect effect in boundary layer clouds forming in polluted continental outbreaks. This paper describes the objectives of the project, the instrumental setup and the sampling strategy. Preliminary results published in additional papers are briefly summarized."
"7102739935;7005703578;55768583400;","Representing twentieth-century space-time climate variability. Part II: Development of 1901-96 monthly grids of terrestrial surface climate",2000,"10.1175/1520-0442(2000)013<2217:RTCSTC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034233140&doi=10.1175%2f1520-0442%282000%29013%3c2217%3aRTCSTC%3e2.0.CO%3b2&partnerID=40&md5=b0a2a60041e25fcd2ee3d36a2354075c","The authors describe the construction of a 0.5°lat-long gridded dataset of monthly terrestrial surface climate for the period of 1901-96. The dataset comprises a suite of seven climate elements: precipitation, mean temperature, diurnal temperature range, wet-day frequency, vapor pressure, cloud cover, and ground frost frequency. The spatial coverage extends over all land areas, including oceanic islands but excluding Antarctica. Fields of monthly climate anomalies, relative to the 1961-90 mean, were interpolated from surface climate data. The anomaly grids were then combined with a 1961-90 mean monthly climatology (described in Part I) to arrive at grids of monthly climate over the 96-yr period. The primary variables-precipitation, mean temperature, and diurnal temperature range-were interpolated directly from station observations. The resulting time series are compared with other coarser-resolution datasets of similar temporal extent. The remaining climatic elements, termed secondary variables, were interpolated from merged datasets comprising station observations and, in regions where there were no station data, synthetic data estimated using predictive relationships with the primary variables. These predictive relationships are described and evaluated. It is argued that this new dataset represents an advance over other products because (i) it has higher spatial resolution than other datasets of similar temporal extent, (ii) it has longer temporal coverage than other products of similar spatial resolution, (iii) it encompasses a more extensive suite of surface climate variables than available elsewhere, and (iv) the construction method ensures that strict temporal fidelity is maintained. The dataset should be of particular relevance to a number of applications in applied climatology, including large-scale biogeochemical and hydrological modeling, climate change scenario construction, evaluation of regional climate models, and comparison with satellite products. The dataset is available from the Climatic Research Unit and is currently being updated to 1998.The authors describe the construction of a 0.5° lat-long gridded dataset of monthly terrestrial surface climate for the period of 1901-96. The dataset comprises a suite of seven climate elements: precipitation, mean temperature, diurnal temperature range, wet-day frequency, vapor pressure, cloud cover, and ground frost frequency. The spatial coverage extends over all land areas, including oceanic islands but excluding Antarctica. Fields of monthly climate anomalies, relative to the 1961-90 mean, we interpolated from surface climate data. The anomaly grids were then combined with a 1961-90 mean monthly climatology (described in Part I) to arrive at grids of monthly climate over the 96-yr period. The primary variables - precipitation, mean temperature, and diurnal temperature range - were interpolated directly from station observations. The resulting time series are compared with other coarser-resolution datasets of similar temporal extent. The remaining climatic elements, termed secondary variables, were interpolated from merged datasets comprising station observations and, in regions where there were no station data, synthetic data estimated using predictive relationships with the primary variables. These predictive relationships are described and evaluated. It is argued that this new dataset represents an advance over other products because (i) it has higher spatial resolution than other datasets of similar temporal extent, (ii) it has longer temporal coverage than other products of similar spatial resolution, (iii) it encompasses a more extensive suite of surface climate variables than available elsewhere, and (iv) the construction method ensures that strict temporal fidelity is maintained. The dataset should be of particular relevance to a number of applications in applied climatology, including large-scale biogeochemical and hydrological modeling, climate change scenario construction, evaluation of regional climate models, and comparison with satellite products. The dataset is available from the Climatic Research Unit and is currently being updated to 1998."
"35584010200;35619212800;7006432091;","The 1997 Pan American Climate Studies Tropical Eastern Pacific Process Study. Part II: Stratocumulus region",2000,"10.1175/1520-0477(2000)081<0483:TPACST>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000725847&doi=10.1175%2f1520-0477%282000%29081%3c0483%3aTPACST%3e2.3.CO%3b2&partnerID=40&md5=1c2aabeccb1ea357a0b7ff5ebc7197f6","An ad hoc experiment in the marine stratocumulus region to the west of Mexico was conducted from 29 August to 6 September 1997 as part of the Pan American Climate Studies Tropical Eastern Pacific Process Study cruise on the National Oceanic and Atmospheric Administration ship Ronald H. Brown after a medical emergency cut short the planned time in the eastern Pacific ITCZ. The joint variation of cloud structure, drizzle, and tropospheric stratification was documented by a combination of three hourly upper air soundings, scanning C-band radar, hourly cloud photography, and visual observation. The sensitive C-band Doppler radar mounted on the ship was able to obtain observations of drizzle cells with regions of greater than 10 dBZ of 2-3-km scale in the horizontal and peak reflectivities of greater than 25 dBZ."
"7102913661;7006705919;7005513582;6701743200;55207447000;","Sulfur chemistry in the National Center for Atmospheric Research Community Climate Model: Description, evaluation, features, and sensitivity to aqueous chemistry",2000,"10.1029/1999JD900773","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033788295&doi=10.1029%2f1999JD900773&partnerID=40&md5=fde82a0160a928ef015704f82e2aa75b","Sulfur chemistry has been incorporated in the National Center for Atmospheric Research Community Climate Model in an internally consistent manner with other parameterizations in the model. The model predicts mixing ratios of dimethylsulfide (DMS), SO2, SO42-, H2O2. Processes that control the mixing ratio of these species include the emissions of DMS and SO2, transport of each species, gas- and aqueous-phase chemistry, wet deposition, and dry deposition of species. Modeled concentrations agree quite well with observations for DMS and H2O2, fairly well for SO2, and not as well for SO42-. The modeled SO42- tends to underestimate observed SO42- at the surface and overestimate observations in the upper troposphere. The SO2 and SO42- species were tagged according to the chemical production pathway and whether the sulfur was of anthropogenic or biogenic origin. Although aqueous-phase reactions in cloud accounted for 81% of the sulfate production rate, only ∼50-60% of the sulfate burden in the troposphere was derived from cloud chemistry. Because cloud chemistry is an important source of sulfate in the troposphere, the importance of H2O2 concentrations and pH values was investigated. When prescribing H2O2 concentrations to clear-sky values instead of predicting H2O2, the global-averaged, annual-averaged in-cloud production of sulfate increased. Setting the pH of the drops to 4.5 also increased the in-cloud production of sulfate. In both sensitivity simulations, the increased in-cloud production of sulfate decreased the burden of sulfate because less SO2 was available for gas-phase conversion, which contributes more efficiently to the tropospheric sulfate burden than does aqueous-phase conversion. Copyright 2000 by the American Geophysical Union."
"7003278104;7102389501;","Analysis of ocean surface heat fluxes in a NOGAPS climate simulation: Influences from convection, clouds and dynamical processes",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785916&partnerID=40&md5=eb644c19375fb8c749b97b3ffb44f30e","This study examines the simulation quality of the surface heat flux fields produced during a climate simulation of the Navy Operational Global Atmospheric Prediction System, version 3.4, with a reduced spectral truncation of T63 and 18 levels (herineafter referred to as NOGAPS-CL). Comparisons are made between a 17-year NOGAPS-CL simulation using monthly sea surface temperatures as surface boundary conditions and a number of validating data sets consisting of ship, satellite, and/or reanalysis-based surface heat fluxes, precipitation, top of the atmosphere radiation budget, water vapor, cloud frequency, surface wind stress, and tropospheric winds. In this extended, long-range integration, NOGAPS-CL underpredicts the net surface shortwave flux in much of the subtropical oceans and overpredicts the net shortwave flux in the western Pacific warm pool and the midlatitude oceans, when compared to several satellite-derived climatological data sets. In addition, NOGAPS-CL over predicts the latent heat flux in much of the subtropics and under predicts the latent heat flux over the northern ocean western boundary currents and under the storm track regions that extend eastward from them. These shortwave and evaporation biases combine to produce errors in the surface net heat flux, with too little heat entering the subtropical/tropical oceans and too much heat loss in the midlatitudes oceans. Examination of related quantities indicates that the tropical climate biases are coupled to shortcomings in the convective cloud and/or boundary layer parameterizations which leads to the premature release of moist instability from the boundary layer in regions just outside the deep convective zones. This leads to enhanced climatological cloudiness, rainfall, and surface evaporation, as well as to a reduction in the surface shortwave flux and outgoing longwave radiation (OLR), in the subtropical regions. Furthermore, because of this early release of the moist static energy, there is a reduction in clouds, rainfall and water vapor content, as well as enhanced surface shortwave flux and outgoing longwave radiation, in the deep convective zones. The reduction in rainfall and enhanced OLR reduces the strength of the tropical large-scale circulation, which in turn reduces the strength of the subsidence in the subtropical regions which normally acts to suppress the convection processes in these regions. The implications of these results are discussed in terms of the relationship among the forecast model climatological surface fluxes, convection, clouds, and the dynamical processes, as well as their similarities to other climate models and their possible impact on the simulation of transient systems."
"57214594557;6701682333;7004390467;","A New Database of High Arctic Climate Data from the Polar Continental Shelf Project Archives",2000,"10.1175/1520-0477(2000)081<2621:ANDOHA>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000598897&doi=10.1175%2f1520-0477%282000%29081%3c2621%3aANDOHA%3e2.3.CO%3b2&partnerID=40&md5=a336a12430851af7fbb758075ce14dcc","A set of nonstandard climate data from the Canadian High Arctic is made available. This consists of 20 yr (1974-93) of surface-based climate observations gathered at short-term field research camps supported by the Polar Continental Shelf Project, a Canadian federal agency responsible for Arctic research support. These data were gathered in the spring and summer months from locations throughout the Canadian Arctic Archipelago. Twice-daily observations, totaling 58 000 individual records, along with associated station information, were compiled. Observed climatic elements include dry-bulb temperature, wind speed and direction, and total cloud cover. These data are useful for research into local-scale climates; support for site-specific, nonclimate studies; corroborating established regional synoptic patterns; and calibration of satellite temperature observations."
"7005892157;","Dissipative heating in climate models",2000,"10.1256/smsqj.56407","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034068654&doi=10.1256%2fsmsqj.56407&partnerID=40&md5=7843adb966eda8bb3d1e5adf4efc9efa","The various strategies towards dissipative heating in meteorological models are reviewed. The strategies are implicit formulations, explicit formulations, and exclusion. A thermodynamic formulation based on dry static energy, which has long been used in hydrostatic models, implicitly includes dissipative heating. Many modern non-hydrostatic mesoscale models, being based on potential temperature, do not include any dissipative heating. The National Center for Atmospheric Research community climate model (CCM3) explicitly formulates the dissipative heating for the resolved motion, which is based upon potential temperature, but, uses the implicit formulation for the sub-grid motion. Those who want to use the mesoscale-model formulation as a cloud-resolving climate model are advised to consider the effect of dissipative heating. We show a dry radiative-convective model, formulated without dissipative heating, in which climate equilibrium occurs with a net inward radiative flux of about 18 W m-2 at the top of the atmosphere, and a surface temperature that is 8 K too low."
"24322005900;7006698304;","The response of the ECMWF model to changes in the cloud overlap assumption",2000,"10.1175/1520-0493(2000)128<1707:TROTEM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033912547&doi=10.1175%2f1520-0493%282000%29128%3c1707%3aTROTEM%3e2.0.CO%3b2&partnerID=40&md5=46466cad4c3799e1f25c4f98880d5d20","The role of the cloud overlap assumption (COA) in organizing the cloud distribution through its impact on the vertical heating/cooling rate profile by radiative and precipitative/evaporative processes is studied in a series of experiments with a recent version of the ECMWF general circulation model, which includes a prognostic cloud scheme. First, the radiative forcing initially obtained for different COAs (maximum, MAX; maximum-random, MRN; and random, RAN overlap) is discussed from results of one-dimensional radiation-only computations. Ensembles of TL95 L31 simulations for the winter 1987/88 (November-December-January-February) are then used, with the three different overlap assumptions applied on radiation only (RAD), evaporation/precipitation only (EP). or both (EPR). In RAD and EPR simulations, the main effect of a change in COA is felt by the model through the change in radiative heating profile, which affects in turn most aspects of the energy and hydrological budget. However, the role of the COA on the precipitation/evaporation, albeit smaller, is not negligible. In terms of radiative fluxes at the top and surface in the RAD and EPR simulations, RAN differs much more from MRN than MAX does, showing that for this vertical resolution, the majority of the clouds appear more in contiguous layers than as independent layers. Given the large sensitivity of both the model total cloud cover and surface and top-of-the-atmosphere radiation fields to the cloud overlap assumption used in the radiation and cloud scheme, it is very important that these quantities are not validated independently of each other, and of the radiative cloud overlap assumption. The cloud overlap assumption for precipitation processes should be made consistent with that for radiation."
"6603452942;","Cloud predictions diagnosed from global weather model forecasts",2000,"10.1175/1520-0493(2000)128<3538:CPDFGW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033657713&doi=10.1175%2f1520-0493%282000%29128%3c3538%3aCPDFGW%3e2.0.CO%3b2&partnerID=40&md5=711d79513af854acf7e06a41bad5db25","The U.S. Air Force has a long history of investment in cloud analysis and prediction operations. Their need for accurate cloud cover information has resulted in routine production of global cloud analyses (from their RTNEPH analysis model) and forecasts (using their ADVCLD cloud trajectory forecast model) over many years. With the advancement of global numerical weather prediction technology and resulting forecast accuracy of noncloud meteorological quantities, it is of interest to determine if such technology could be used to benefit cloud cover forecasting. In this paper, a model output statistics approach to diagnosing cloud cover from forecast fields generated by a global numerical weather prediction model is presented. Cloud characteristics information obtained from the RTNEPH cloud analysis supplied the cloud predictands, and forecast fields from the U.S. Navy Operational Global Atmospheric Prediction System global weather prediction model provided the weather variable predictors. RTNEPH layer cloud cover was assigned to three cloud decks (high, middle, and low) based on reported cloud-base altitude, and RTNEPH total cloud cover was used as a separate predictand. Multiple discriminant analysis (MDA) was used to develop the predictand-predictor relationships for each cloud deck and total cloud using 5 days of twice-daily cloud analyses and corresponding forecasts for 30° latitude zones. The consequent relationships were applied to the forecasts fields from the forecast initialized on the day following each 5-day development period to diagnose cloud cover forecasts for the Northern or Southern Hemisphere. In this study, cloud cover forecasts were diagnosed from global NWP model forecasts on hemispheric polar stereographic map projections with a grid spacing of 96 km. The diagnosed cloud forecasts (DCFs) were verified against the RTNEPH analyses for forecast durations of 12-72 h at 12-h intervals. Also verified were 12-48-h cloud cover forecasts (deck and total) from the ADVCLD cloud trajectory model, and from persistence (RTNEPH at initial forecast time). Biases from all three methods were generally small. The DCFs were significantly better than ADVCLD and persistence in all decks and total cloud, at almost all forecast durations in rmse and 20/20 score. ADVCLD scored better in these measures only at 12 h in total cloud, suggesting the possibility of a crossover in superior prediction skill from trajectory to diagnostic method somewhere between 12 and 24 h. DCF better preserved the cloud cover frequency distribution than did ADVCLD. ADVCLD displayed a greater degree of spatial variation inherent in RTNEPH cloud cover than did DCF. Both ADVCLD and DCF visual depictions of hemispheric total cloud cover appeared to provide useful cloud cover forecast information when compared with RTNEPH depictions. The advantages of the diagnosed cloud forecast algorithm presented in this study make it an excellent candidate for operational cloud cover prediction. It is expected that as cloud cover analyses are improved, the trajectory and diagnostic methods will prove complementary with the former more skillful at short-term predictions, and the latter better at long-term forecasts."
"7003531755;23082420800;7006248174;","Glacial cooling in the Tropics: Exploring the roles of tropospheric water vapor, surface wind speed, and boundary layer processes",2000,"10.1175/1520-0469(2000)057<2144:GCITTE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034233628&doi=10.1175%2f1520-0469%282000%29057%3c2144%3aGCITTE%3e2.0.CO%3b2&partnerID=40&md5=cb174381c6451ff933dd1020f1a9f2a0","This paper is a modeling study of possible roles for tropospheric water vapor, surface wind speed, and boundary layer processes in glacial cooling in the Tropics. The authors divide the Tropics into a region of persistent deep convection and a subtropical region with no deep convection. The regions are coupled via a radiatively driven Hadley cell and a wind-driven meridional overturning cell in the ocean. Radiation and the convective boundary layer (CBL) are treated in some detail. The amount of tropical cooling depends on the height of the tropospheric drying and on the extent to which cloud water in the CBL is converted into rainwater. In the most realistic case where the CBL clouds precipitate, variations in CBL depth are small, and the tropical SST becomes most sensitive to drying immediately above the CBL. Reducing the relative humidity of the entire troposphere above the subcloud layer by about 10%-20% cools the tropical SST by just over 2 K. It is shown that this climate sensitivity arises from a complex balance of processes that control the depth of the CBL, its greenhouse trapping, and the albedo of boundary layer clouds. An increase in surface wind speed, such as occurs in simulations of the last glacial maximum with coupled general circulation models, substantially reduces the SST although the change in surface air temperature is less. The Milankovitch cycles are expected to cause changes in atmosphere and ocean circulation. It appears that a circulation change that causes the lower midtroposphere to dry would be an effective way to induce strong cooling of tropical climate.This paper is a modeling study of possible roles for tropospheric water vapor, surface wind speed, and boundary layer processes in glacial cooling in the Tropics. The authors divide the Tropics into a region of persistent deep convection and a subtropical region with no deep convection. The regions are coupled via a radiatively driven Hadley cell and a wind-driven meridional overturning cell in the ocean. Radiation and the convective boundary layer (CBL) are treated in some detail. The amount of tropical cooling depends on the height of the tropospheric drying and on the extent to which cloud water in the CBL is converted into rainwater. In the most realistic case where the CBL clouds precipitate, variations in CBL depth are small, and the tropical SST becomes most sensitivity arises from a complex balance the CBL. Reducing the relative humidity of the entire troposphere above the subcloud layer by about 10%-20% cools the tropical SST by just over 2 K. It is shown that this climate sensitivity arises from a complex balance of processes that control the depth of the CBL, its greenhouse trapping, and the albedo of boundary layer clouds. An increase in surface wind speed, such as occurs in simulations of the last glacial maximum with coupled general circulation models, substantially reduces the SST although the change in surface air temperature is less. The Milankovitch cycles are expected to cause changes in atmosphere and ocean circulation. It appears that a circulation change that causes the lower midtroposphere to dry would be an effective way to induce strong cooling of tropical climate."
"35572096100;7007108728;7102331727;","Ice particle habits in stratiform clouds",2000,"10.1256/smsqj.56912","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033762938&doi=10.1256%2fsmsqj.56912&partnerID=40&md5=cdf76625abecda4195be11aea3ea3fd5","Ice crystals in clouds in the atmosphere have shapes that relate to their density, terminal fall velocity, growth rate and radiative properties. In calculations for climate-change predictions, forecasting of precipitation, and remote-sensing retrievals, idealized crystal shapes such as columns, needles, plates and dendrites are often assumed. The objective of this work is to study the frequency of occurrence of different habits of ice particles in natural clouds from aircraft observations. Images of cloud particles were measured by a PMS Optical Array Probe-2DC at 25 μm resolution installed on the National Research Council Convair-580. The processing of particle images was conducted with a newly developed algorithm for pattern recognition. Data were collected during four field projects in the Canadian and US Arctic over the North Atlantic near Newfoundland, and over the Great Lakes. Approximately 5 x 106 images of cloud particles having a size larger than 125 μm were analysed. The cloud particles were classified into four categories: spheres, irregulars, needles/columns and dendrites. The habit classification of particles was done for three different size ranges: &gt;125 μm, &gt;250 μm, and &gt;500 μm. The frequency of occurrence of different habits was found for each 5 degC temperature interval in the range -45°C &lt;T &lt;0°C. It was concluded that the majority of ice particles in natural clouds were of irregular shape. The frequency of occurrence of irregular ice decreases with increasing particle size. On average, the concentration of particles larger than 125 μm was approximately constant down to -35°C, whereas the concentration of particles larger than 500 μm decreased at temperatures below -15°C. Since the data were collected in different climatic zones within many cloud types, and covered a significant cloud path length (3.6 x 104 km), the conclusions are applicable to most stratiform clouds containing ice."
"7101945366;6701608776;6602837158;7006698304;57203053317;6701571700;6603809220;7402717381;7006865796;6603422104;7006864972;","Simulations of a cold front by cloud-resolving, limited-area, and large-scale models, and a model evaluation using in situ and satellite observations",2000,"10.1175/1520-0493(2000)128<3218:SOACFB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034277362&doi=10.1175%2f1520-0493%282000%29128%3c3218%3aSOACFB%3e2.0.CO%3b2&partnerID=40&md5=c1bb3048b9a8ad0958ea4bebf10e4f26","The Global Energy and Water Cycle Experiment has identified the poor representation of clouds in atmospheric general circulation models as one of the major impediments for the use of these models in reliably predicting future climate change. One of the most commonly encountered types of cloud system in midlatitudes is that associated with cyclones. The purpose of this study is to investigate the representation of frontal cloud systems in a hierarchy of models in order to identify their relative weaknesses. The hierarchy of models was classified according to the horizontal resolution: cloud-resolving models (5-km resolution), limited-area models (20-km resolution), coarse-grid single-column models (300 km), and an atmospheric general circulation model (>100 km). The models were evaluated using both in situ and satellite data. The study shows, as expected, that the higher-resolution models give a more complete description of the front and capture many of the observed nonlinear features of the front. At the low resolution, the simulations are unable to capture the front accurately due to the lack of the nonlinear features seen in the high-resolution simulations. The model intercomparison identified problems in applying single-column models to rapidly advecting baroclinic systems. Mesoscale circulations driven by subgrid-scale dynamical, thermodynamical, and microphysical processes are identified as an important feedback mechanism linking the frontal circulations and the cloud field. Finally it is shown that the same techniques used to validate climatological studies with International Satellite Cloud Climatology Project data are also valid for case studies, thereby providing a methodology to generalize the single case studies to climatological studies.The Global Energy and Water Cycle Experiment has identified the poor representation of clouds in atmospheric general circulation models as one of the major impediments for the use of these models in reliably predicting future climate change. One of the most commonly encountered types of cloud system in midlatitudes is that associated with cyclones. The purpose of this study is to investigate the representation of frontal cloud systems in a hierarchy of models in order to identify their relative weaknesses. The hierarchy of models was classified according to the horizontal resolution: cloud-resolving models (5-km resolution), limited-area models (20-km resolution), coarse-grid single-column models (300 km), and an atmospheric general circulation model (>100 km). The models were evaluated using both in situ and satellite data. The study shows, as expected, that the higher-resolution models give a more complete description of the front and capture many of the observed nonlinear features of the front. At the low resolution, the simulations are unable to capture the front accurately due to the lack of the nonlinear features seen in the high-resolution simulations. The model intercomparison identified problems in applying single-column models to rapidly advecting baroclinic systems. Mesoscale circulations driven by subgrid-scale dynamical, thermodynamical, and microphysical processes are identified as an important feedback mechanism linking the frontal circulations and the cloud field. Finally it is shown that the same techniques used to validate climatological studies with International Satellite Cloud Climatology Project data are also valid for case studies, thereby providing a methodology to generalize the single case studies to climatological studies."
"7201783608;24322005900;7006698304;7004461962;7004691135;","Revision of convection, radiation and cloud schemes in the ECMWF Integrated Forecasting System",2000,"10.1256/smsqj.56607","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033861487&doi=10.1256%2fsmsqj.56607&partnerID=40&md5=326a917b0612d459fd2dd6dc0f7968a5","Revisions to the convection, radiation and cloud schemes recently introduced into the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) are described, together with discussion of their impact upon model performance. Seasonal simulations with observed sea surface temperatures (SSTs) for June/July/August 1987 and December/January/February 1987/88 with a low-resolution (T63) version of the model are used to assess the impact of the revised schemes, concentrating upon tropical climate and variability. While the revisions improve the physical basis of the schemes, and each improves aspects of the seasonal climate, overall improvement does not result until the changes are combined. Biases in simulated temperature and top-of-atmosphere and surface energy budgets are reduced, leading to a substantial decrease of an equatorial SST cold bias in coupled ocean-atmosphere simulations used in seasonal forecasting. At higher resolution (T213) changes to temperature and wind fields are similar to those found in seasonal simulations, with little impact upon medium-range forecast performance in mid latitudes, although these forecasts proved a more critical test of the impact of the schemes upon mid-latitude flows. The paper demonstrates the methodology used in the development of parametrizations of physical processes at ECMWF, and points to the need to balance parametrization improvements especially between schemes which are highly interactive."
"7006698304;7402064802;","A parametrization of the effects of cloud and precipitation overlap for use in general-circulation models",2000,"10.1002/qj.49712656809","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033816617&doi=10.1002%2fqj.49712656809&partnerID=40&md5=80c199c5673e0b8e0d06d7fbdaa8fa42","The necessity for treating the effects of vertically varying cloud fraction when parametrizing microphysical processes in general-circulation models (GCMs) was recently highlighted by Jakob and Klein. In this study a parametrization to include such effects in a GCM is developed, and the new scheme is applied in the ECMWF global model. The basic idea of the new scheme is to separate the model's rain and snow fluxes into a cloudy and a clear-sky part. The scheme is tested using the subgrid-scale precipitation model of Jakob and Klein as a benchmark. The impact of the new scheme on the model climate is also investigated. It is shown that the new parametrization leads to a better representation of the effects of cloud and precipitation overlap, and that it alleviates most of the problems connected with their treatment in the current scheme. Due to the better treatment of cloud and precipitation overlap the new parametrization leads to a reduction in precipitation evaporation and an increase in accretion rates. When tested in seasonal model integrations the new scheme produces a drier tropical mid-troposphere with consequences for the hydrological cycle."
"55687655500;7601318782;7004540083;","Sensitivity of atmospheric radiative heating rate profiles to variations of cloud layer overlap",2000,"10.1175/1520-0442(2000)013<2941:SOARHR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253168&doi=10.1175%2f1520-0442%282000%29013%3c2941%3aSOARHR%3e2.0.CO%3b2&partnerID=40&md5=05fb5265e8856b57be87c49de1909b47","Three different cloud overlap schemes are applied to the International Satellite Cloud Climatology Project (ISCCP) vertical distribution of clouds in the radiative transfer model from the National Aeronautics and Space Administration Goddard Institute for Space Studies climate GCM to study the sensitivity of radiative fluxes and atmospheric radiative heating rate profiles to variations in cloud vertical structure. This study differs from previous ones because the ISCCP dataset constrains the total column optical thickness of the clouds at each location, a fact that is used to constrain cloud overlap occurrence. Moreover, this study considers the effects of cloud vertical structure on both shortwave (SW) and longwave (LW) fluxes at the top of the atmosphere, at the surface, and in the atmosphere. The in-atmosphere net fluxes are decomposed further into vertical profiles of radiative heating and cooling rates. The results show that the changes in the top-of-atmosphere (TOA) and surface (SRF) radiative fluxes vary among the different schemes, depending on the part of the atmosphere-surface system and spectral band (SW and LW) considered, but that the magnitudes of the changes generally are small. The scheme without a total optical thickness constraint produces opposite-signed changes in fluxes (except for the SRF LW flux) and the profile of atmospheric radiative heating rate in comparison with the schemes with the constraint. The constraint on total optical thickness eliminates nearly all of the effects on the total TOA and SRF radiation budget, significantly reducing the frequency of layer overlap occurrence and thereby reducing the effect of overlap on the radiative heating rate profiles. Even when the assumptions are changed to produce a frequency of occurrence of multilayer clouds that is similar to other estimates, the resulting changes in the radiative heating rate profile are quantitatively small. The magnitude of these changes is similar to the magnitude of the total overall cloud effect, however, making the layer overlap critical to accurate determinations of the shape of the radiative heating rate profiles.Three different cloud overlap schemes are applied to the International Satellite Cloud Climatology Project (ISCCP) vertical distribution of clouds in the radiative transfer model from the National Aeronautics and Space Administration Goddard Institute for Space Studies climate GCM to study the sensitivity of radiative fluxes and atmospheric radiative heating rate profiles to variations in cloud vertical structure. This study differs from previous ones because the ISCCP dataset constrains the total column optical thickness of the clouds at each location, a fact that is used to constrain cloud overlap occurrence. Moreover, this study considers the effects of cloud vertical structure on both shortwave (SW) and longwave (LW) fluxes at the top of the atmosphere, at the surface, and in the atmosphere. The in-atmosphere net fluxes are decomposed further into vertical profiles of radiative heating and cooling rates. The results show that the changes in the top-of-atmosphere (TOA) and surface (SRF) radiative fluxes vary among the different schemes, depending on the part of the atmosphere-surface system and spectral band (SW and LW) considered, but that the magnitudes of the changes generally are small. The scheme without a total optical thickness constraint produces opposite-signed changes in fluxes (except for the SRF LW flux) and the profile of atmospheric radiative heating rate in comparison with the schemes with the constraint. The constraint on total optical thickness eliminates nearly all of the effects on the total TOA and SRF radiation budget, significantly reducing the frequency of layer overlap occurrence and thereby reducing the effect of overlap on the radiative heating rate profiles. Even when the assumptions are changed to produce a frequency of occurrence of multilayer clouds that is similar to other estimates, the resulting changes in the radiative heating rate profile are quantitatively small. The magnitude of these changes is similar to the magnitude of the total overall cloud effect, however, making the layer overlap critical to accurate determinations of the shape of the radiative heating rate profiles."
"7403027443;7006519716;7005297959;","Interpolation of daily global solar radiation with thin plate smoothing splines",2000,"10.1007/s007040070036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033928190&doi=10.1007%2fs007040070036&partnerID=40&md5=6e7c2ce5426cc40b51c88e0f897d7e25","Thin plate smoothing splines incorporating topographic dependence were used to interpolate daily global solar radiation in the Bavarian forest ecosystem monitoring network, with the degree of data smoothing determined by minimizing the generalized cross validation. A simple cross validation method was used to discuss the spatial distribution of mean relative errors at 18 forest climate stations. The results show that, from this network 14%-30% mean relative errors can be expected for most of these forest climate stations in summer, and 20%-30% mean relative errors can be found at a few of forest climate stations in winter. Time-averaging can reduce these interpolation errors. In this network a mean relative error of 10% can be expected for weekly and biweekly mean solar radiation at most of forest climate stations in summer. Large errors are related to low radiation amount under heavy cloud cover. Mean relative errors increase as daily global solar radiation decreases."
"7006204393;7005626683;35494005000;7005807606;7101959253;55740664200;7004449177;","Objective determination of cloud heights and radar reflectivities using a combination of active remote sensors at the ARM CART sites",2000,"10.1175/1520-0450(2000)039<0645:ODOCHA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033933742&doi=10.1175%2f1520-0450%282000%29039%3c0645%3aODOCHA%3e2.0.CO%3b2&partnerID=40&md5=9bb16cc0e07579101d9504b06ddf4bd1","The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Program is deploying sensitive, millimeter-wave cloud radars at its Cloud and Radiation Test Bed (CART) sites in Oklahoma, Alaska, and the tropical western Pacific Ocean. The radars complement optical devices, including a Belfort or Vaisala laser ceilometer and a micropulse lidar, in providing a comprehensive source of information on the vertical distribution of hydrometeors overhead at the sites. An algorithm is described that combines data from these active remote sensors to produce an objective determination of hydrometeor height distributions and estimates of their radar reflectivities, vertical velocities, and Doppler spectral widths, which are optimized for accuracy. These data provide fundamental information for retrieving cloud microphysical properties and assessing the radiative effects of clouds on climate. The algorithm is applied to nine months of data from the CART site in Oklahoma for initial evaluation. Much of the algorithm's calculations deal with merging and optimizing data from the radar's four sequential operating modes, which have differing advantages and limitations, including problems resulting from range sidelobes, range aliasing, and coherent averaging. Two of the modes use advanced phase-coded pulse compression techniques to yield approximately 10 and 15 dB more sensitivity than is available from the two conventional pulse modes. Comparison of cloud-base heights from the Belfort ceilometer and the micropulse lidar confirms small biases found in earlier studies, but recent information about the ceilometer brings the agreement to within 20-30 m. Merged data of the radar's modes were found to miss approximately 5.9% of the clouds detected by the laser systems. Using data from only the radar's two less-sensitive conventional pulse modes would increase the missed detections to 22%-34%. A significant remaining problem is that the radar's lower-altitude data are often contaminated with echoes from nonhydrometeor targets, such as insects."
"7003377229;35453054300;","A climate version of the regional atmospheric modeling system",2000,"10.1007/s007040070031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033912307&doi=10.1007%2fs007040070031&partnerID=40&md5=c5b0667c1fa2a2037bc5b67179d33234","The Regional Atmospheric Modeling System (RAMS) has been widely used to simulate relatively short-term atmospheric processes. To perform full-year to multi-year model integrations, a climate version of RAMS (ClimRAMS) has been developed, and is used to simulate diurnal, seasonal, and annual cycles of atmospheric and hydrologic variables and interactions within the central United States during 1989. The model simulation uses a 200-km grid covering the conterminous United States, and a nested, 50-km grid covering the Great Plains and Rocky Mountain states of Kansas, Nebraska, South Dakota, Wyoming, and Colorado. The model's lateral boundary conditions are forced by six-hourly NCEP reanalysis products. ClimRAMS includes simplified precipitation and radiation sub-models, and representations that describe the seasonal evolution of vegetation-related parameters. In addition, ClimRAMS can use all of the general RAMS capabilities, like its more complex radiation sub-models, and explicit cloud and precipitation microphysics schemes. Thus, together with its nonhydrostatic and fully-interactive telescoping-grid capabilities, ClimRAMS can be applied to a wide variety of problems. Because of non-linear interactions between the land surface and atmosphere, simulating the observed climate requires simulating the observed diurnal, synoptic, and seasonal cycles. While previous regional climate modeling studies have demonstrated their ability to simulate the seasonal cycles through comparison with observed monthly-mean temperature and precipitation data sets, this study demonstrates that a regional climate model can also capture observed diurnal and synoptic variability. Observed values of daily precipitation and maximum and minimum screen-height air temperature are used to demonstrate this ability."
"57201410408;7006095466;","Parameterization of convective momentum transport in highly baroclinic conditions",2000,"10.1175/1520-0469(2000)057<3035:POCMTI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034277368&doi=10.1175%2f1520-0469%282000%29057%3c3035%3aPOCMTI%3e2.0.CO%3b2&partnerID=40&md5=9a766bc02077c256f91615e9a43c40ff","The organization of convection by vertical shear strongly affects the transport of horizontal momentum, yet the concept of organization has received little attention in convective parameterization. Here the focus is on open-cellular convection in cold-air outbreaks under strongly baroclinic conditions that occur to the rear of midlatitude cyclones. The principles derived herein are envisaged to apply to baroclinic advection at large in similar shear flows. Open-cellular convection, forced by surface fluxes of sensible and latent heat and organized by unidirectional shear, is simulated using a three-dimensional cloud-resolving numerical model. The effects of the in-cloud pressure field, organization, and shear on momentum transport are quantified for the simulated clouds. A simple analytic model of blocked overturning provides dynamical insight into downgradient momentum transport by the simulated three-dimensional cumulonimbus ensemble. The overturning circulation having vorticity of the same sign as the ambient shear maintains the far-field flow, while the blocking effect decelerates in-cloud momentum. The combined effect is to maintain the mean flow somewhat below its undisturbed value. The numerical results and analytic predictions are used to evaluate and interpret two parameterization schemes for convective momentum transport used in operational global weather prediction and climate models at the U.K. Meteorological Office and the European Centre for Medium-Range Weather Forecasts. Finally, the authors comment on how the downgradient momentum transport by three-dimensional cumulus convection contrasts with momentum-mixing concepts as well as countergradient momentum transport by two-dimensional squall lines.The organization of convection by vertical shear strongly affects the transport of horizontal momentum, yet the concept of organization has received little attention in convective parameterization. Here the focus is on open-cellular convection in cold-air outbreaks under strongly baroclinic conditions that occur to the rear of midlatitude cyclones. The principles derived herein are envisaged to apply to baroclinic advection at large in similar shear flows. Open-cellular convection, forced by surface fluxes of sensible and latent heat and organized by unidirectional shear, is simulated using a three-dimensional cloud-resolving numerical model. The effects of the in-cloud pressure field, organization, and shear on momentum transport are quantified for the simulated clouds. A simple analytic model of blocked overturning provides dynamical insight into downgradient momentum transport by the simulated three-dimensional cumulonimbus ensemble. The overturning circulation having vorticity of the same sign as the ambient shear maintains the far-field flow, while the blocking effect decelerates in-cloud momentum. The combined effect is to maintain the mean flow somewhat below its undisturbed value. The numerical results and analytic predictions are used to evaluate and interpret two parameterization schemes for convective momentum transport used in operational global weather prediction and climate models at the U.K. Meteorological Office and the European Centre for Medium-Range Weather Forecasts. Finally, the authors comment on how the downgradient momentum transport by three-dimensional cumulus convection contrasts with momentum-mixing concepts as well as countergradient momentum transport by two-dimensional squall lines."
"7004938676;57203052274;7004215973;49161128400;57202521210;","Minerals in the air: An environmental perspective",2000,"10.1080/00206810009465101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033842209&doi=10.1080%2f00206810009465101&partnerID=40&md5=f90750ece7e65a12b7ebc90fccd424df","The troposphere comprises roughly the lowest 10 km of the atmosphere, the part we inhabit, that envelops us, and that we inhale and look through every day of our lives. Clouds, rain, all manner of storms, and other aspects of weather originate within it, and it contains 85% of the mass of the atmosphere, including aerosol particles. These particles, like greenhouse gases, can influence climate. Mineral particles are major constituents of this aerosol. Their sizes, shapes, compositions, and degrees of agglomeration can all be determined using transmission electron microscopy. These variables have, to a considerable extent, been overlooked in studies of atmospheric chemistry and provide an important potential area of research for geoscientists. © 2000 Taylor & Francis Group, LLC."
"7003666669;7202208382;7403282069;6701464294;8424202400;7005814217;6603568514;7402064802;7103119050;57203053317;57199547660;7004299063;6603809220;7102577095;6701413579;7004160106;7402390191;7401936984;6603307960;55745955800;","A comparison of single column model simulations of summertime midlatitude continental convection",2000,"10.1029/1999JD900971","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033759773&doi=10.1029%2f1999JD900971&partnerID=40&md5=55079a57e438bfb2d27476aa6456d03a","Eleven different single-column models (SCMs) and one cloud ensemble model (GEM) are driven by boundary conditions observed at the Atmospheric Radiation Measurement (ARM) program southern Great Plains site for a 17 day period during the summer of 1995. Comparison of the model simulations reveals common signatures identifiable as products of errors in the boundary conditions. Intermodel differences in the simulated temperature, humidity, cloud, precipitation, and radiative fluxes reflect differences in model resolution or physical parameterizations, although sensitive dependence on initial conditions can also contribute to intermodel differences. All models perform well at times but poorly at others. Although none of the SCM simulations stands out as superior to the others, the simulation by the GEM is in several respects in better agreement with the observations than the simulations by the SCMs. Nudging of the simulated temperature and humidity toward observations generally improves the simulated cloud and radiation fields as well as the simulated temperature and humidity but degrades the precipitation simulation for models with large temperature and humidity biases without nudging. Although some of the intermodel differences have not been explained, others have been identified as model problems that can be or have been corrected as a result of the comparison. Copyright 2000 by the American Geophysical Union."
"7406372329;7102389501;7407038982;","Dynamic and thermodynamic regulation of ocean warming",2000,"10.1175/1520-0469(2000)057<3353:DATROO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034298824&doi=10.1175%2f1520-0469%282000%29057%3c3353%3aDATROO%3e2.0.CO%3b2&partnerID=40&md5=86f830713f740c7b7c69cb7256dd15d1","The relative roles of clouds, surface evaporation, and ocean heat transport in limiting maximum sea surface temperature (SSTs) in the western Pacific warm pool are investigated by means of simple and intermediate coupled ocean-atmosphere models. The authors first take an analytical approach by constructing a conceptual two-box model that contains dynamic coupling among the Walker circulation, SST, and ocean thermocline and thermodynamic coupling, which includes shortwave and longwave cloud forcing and latent and sensible heat fluxes at the ocean surface. In a realistic parameter regime, the three mechanisms mentioned above are all essential in limiting the SSTs within the observed range. The lack of any one mechanism would lead to an equilibrium SST that is too high, although unstable warming due to the super greenhouse effect would not occur. The analysis of the surface heat balance from the simple box model indicates that in the western Pacific warm pool, cloud reflection has a dominant effect, followed by evaporation and ocean dynamics. The simple model results are further evaluated numerically by using an intermediate coupled ocean-atmosphere model. With the forcing of the annual-mean solar radiation, this model is capable of simulating a realistic annual mean climate in the tropical Pacific. The authors then introduce an initial SST perturbation and examine how the perturbation evolves with time in the presence of clouds, surface evaporation, and ocean dynamic processes. Four experiments have been designed. In the first three experiments, each of the three processes is studied separately; in the last experiment, they are combined. The intermediate model results indicate that in the western Pacific warm pool, the largest negative feedback comes from the cloud shortwave radiation forcing, followed by the surface evaporation and ocean heat transport. The sensitivity of the model to various initial SST perturbation patterns is also investigated.The relative roles of clouds, surface evaporation, and ocean heat transport in limiting maximum sea surface temperatures (SSTs) in the western Pacific warm pool are investigated by means of simple and intermediate coupled ocean-atmosphere models. The authors first take an analytical approach by constructing a conceptual two-box model that contains dynamic coupling among the Walker circulation, SST, and ocean thermocline and thermodynamic coupling, which includes shortwave and longwave cloud forcing and latent and sensible heat fluxes at the ocean surface. In a realistic parameter regime, the three mechanisms mentioned above are all essential in limiting the SSTs within the observed range. The lack of any one mechanism would lead to an equilibrium SST that is too high, although unstable warming due to the super greenhouse effect would not occur. The analysis of the surface heat balance from the simple box model indicates that in the western Pacific warm pool, cloud reflection has a dominant effect, followed by evaporation and ocean dynamics. The simple model results are further evaluated numerically by using an intermediate coupled ocean-atmosphere model. With the forcing of the annual-mean solar radiation, this model is capable of simulating a realistic annual mean climate in the tropical Pacific. The authors then introduce an initial SST perturbation and examine how the perturbation evolves with time in the presence of clouds, surface evaporation, and ocean dynamic processes. Four experiments have been designed. In the first three experiments, each of the three processes is studied separately; in the last experiment, they are combined. The intermediate model results indicate that in the western Pacific warm pool, the largest negative feedback comes from the cloud shortwave radiation forcing, followed by the surface evaporation and ocean heat transport. The sensitivity of the model to various initial SST perturbation patterns is also investigated."
"57203598636;57203140160;6603552038;6602784254;","Numerical uncertainties in the simulation of reversible isentropic processes and entropy conservation",2000,"10.1175/1520-0442(2000)013<3860:NUITSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034319078&doi=10.1175%2f1520-0442%282000%29013%3c3860%3aNUITSO%3e2.0.CO%3b2&partnerID=40&md5=18f57d75d5d7bbaea70893acbc062765","A challenge common to weather, climate, and seasonal numerical prediction is the need to simulate accurately reversible isentropic processes in combination with appropriate determination of sources/sinks of energy and entropy. Ultimately, this task includes the distribution and transport of internal, gravitational, and kinetic energies, the energies of water substances in all forms, and the related thermodynamic processes of phase changes involved with clouds, including condensation, evaporation, and precipitation processes. All of the processes noted above involve the entropies of matter, radiation, and chemical substances, conservation during transport, and/or changes in entropies by physical processes internal to the atmosphere. With respect to the entropy of matter, a means to study a model's accuracy in simulating internal hydrologic processes is to determine its capability to simulate the appropriate conservation of potential and equivalent potential temperature as surrogates of dry and moist entropy under reversible adiabatic processes in which clouds form, evaporate, and precipitate. In this study, a statistical strategy utilizing the concept of ""pure error"" is set forth to assess the numerical accuracies of models to simulate reversible processes during 10-day integrations of the global circulation corresponding to the global residence time of water vapor. During the integrations, the sums of squared differences between equivalent potential temperature θe numerically simulated by the governing equations of mass, energy, water vapor, and cloud water and a proxy equivalent potential temperature tθe numerically simulated as a conservative property are monitored. Inspection of the differences of θe and tθe in time and space and the relative frequency distribution of the differences details bias and random errors that develop from nonlinear numerical inaccuracies in the advection and transport of potential temperature and water substances within the global atmosphere. A series of nine global simulations employing various versions of Community Climate Models CCM2 and CCM3-all Eulerian spectral numerics, all semi-Lagrangian numerics, mixed Eulerian spectral, and semi-Lagrangian numerics-and the University of Wisconsin-Madison (UW) isentropic-sigma gridpoint model provides an interesting comparison of numerical accuracies in the simulation of reversibility. By day 10, large bias and random differences were identified in the simulation of reversible processes in all of the models except for the UW isentropic-sigma model. The CCM2 and CCM3 simulations yielded systematic differences that varied zonally, vertically, and temporally. Within the comparison, the UW isentropic-sigma model was superior in transporting water vapor and cloud water/ice and in simulating reversibility involving the conservation of dry and moist entropy. The only relative frequency distribution of differences that appeared optimal, in that the distribution remained unbiased and equilibrated with minimal variance as it remained statistically stationary, was the distribution from the UW isentropic-sigma model. All other distributions revealed nonstationary characteristics with spreading and/or shifting of the maxima as the biases and variances of the numerical differences of θe and tθe amplified.A statistical strategy utilizing the concept of 'pure error' was established to assess the numerical accuracies of models to simulate reversible processes during 10-day integrations of the global circulation corresponding to the global residence time of water vapor. Numerical accuracies in the simulation of reversibility were compared by performing a series of nine global simulations employing various versions of Community Climate Models of CCM2 and CCM3. In general, the CCM2 and CCM3 simulations yielded systematic differences that varied zonally, vertically, and temporally."
"7004378017;7004838908;7003749554;","Influences of storm-embedded orographic gravity waves on cloud liquid water and precipitation",2000,"10.1175/1520-0450(2000)039<0733:IOSEOG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033857779&doi=10.1175%2f1520-0450%282000%29039%3c0733%3aIOSEOG%3e2.0.CO%3b2&partnerID=40&md5=fdf1d0f31bc07ca3b0bcfdd5574c73ec","This study illustrates opportunities for much improved orographic quantitative precipitation forecasting, determination of orographic cloud seedability, and flash flood prediction through state-of-the-art remote sensing and numerical modeling of gravity wave clouds. Wintertime field observations with multiple remote sensors, corroborated in this and related papers with a mesoscale-cloud scale numerical simulation, confirm that storm-embedded gravity waves can have a strong and persistent influence on orographic cloud liquid water (CLW) and precipitation. Where parallel mountain ridges dominate the landscape, an upwind ridge can force the wave action, and a downwind ridge can receive the precipitation. The 1995 Arizona Program was conducted in such terrain. In the scenario examined, traveling waves cyclically caused prefrontal cross-barrier winds that produced gravity waves. Significant cloud bands associated with the waves carried substantial moisture to the area. With the passage and waning of the cloud bands, vapor influxes (precipitable water Pw) cycled through large changes in magnitude, and prefrontal peaks in Pw coincided with the gravity waves in a succession of episodes during a five-day period. Thus, the cyclic trend in Pw and the magnitudes of peak Pw were simple indicators of wave cloud development. The first two cycles, with minor peak Pw, were precursors. Significant wave clouds first appeared during the second episode. During the final two episodes with large vapor influxes, very deep, precipitating wave clouds were coupled with underlying clouds formed in flow up the mountain slopes to create the prefrontal storms. Rain fell on an existing snowpack on the main recipient ridge and, in the end, produced rapid runoff and flash flooding. The gravity waves persistently condensed CLW that averaged 0.5 mm and reached 1.0 mm in the first of the main storm episodes, and averaged 1.0 mm and reached 2.0 mm and more in the second (column-integrated values). These values equaled or exceeded the larger of those represented in liquid water climate datasets for orographic cloud systems in other locations in the West, where only the upslope and not the wave component had been examined. The effect of shifts between cross-barrier and barrier-parallel flows was reflected in abrupt buildups and declines in wave CLW, but the gravity wave clouds persisted for a total of 22 h during the two storm periods. In the wave updrafts, the condensation rate regularly exceeded the consumption rate by ice, even though ice was usually present. Conversion to ice consumed and precipitated wave CLW. Pulses of available Pw and wave CLW on a 2-to 4-h timescale, cyclically followed by partial glaciation, produced the precipitation from the wave clouds. Their seeder effect on the upslope feeder clouds was to enhance the total precipitation from the coupled system. Estimates of the liquid water fluxes in comparison with the precipitation rates suggest precipitation efficiencies in the 11%-33% range from the seeder-feeder couplets. The periods of gravity wave forcing contributed some 80% or more of the total precipitation, and trailing fronts produced the remainder. Several factors derived from the observed availability of CLW determine the potential for precipitation enhancement by seeding wave clouds; these are enumerated. Given demands for improved water supply, the challenge often presented in mountain watersheds of separating seeding opportunities from potential flash flood situations is examined. The results here show that storms that could threaten flash floods can be readily identified by continuous monitoring with polarization radar and in real-time simulations as those with the altitude of the melting level above the elevation of the highest terrain with existing snowpack. In the sense that orographically generated gravity waves will significantly influence cloud water and precipitation, geographic transferability of the results is indicated by the existence of wave-generating and precipitation-generating parallel ridges in many places throughout the world. The quantitative effects will, of course, depend on particulars of the locale such as nature of the prevalent forcing, available moisture, and physical stature of the ridges."
"7006957668;7409376438;7402942478;57211301037;","Improving assimilated global datasets using TMI rainfall and columnar moisture observations",2000,"10.1175/1520-0442(2000)013<4180:IAGDUT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034351743&doi=10.1175%2f1520-0442%282000%29013%3c4180%3aIAGDUT%3e2.0.CO%3b2&partnerID=40&md5=0401755feace52fdc83d92f780f4c30d","A global analysis that optimally combines observations from diverse sources with physical models of atmospheric and land processes can provide a comprehensive description of the climate systems. Currently, such data products contain significant errors in primary hydrological fields such as precipitation and evaporation, especially in the Tropics. In this study it is demonstrated that assimilating precipitation and total precipitable water (TPW) derived from the Tropical Rainfall Measuring Mission Microwave Imager (TMI) can significantly improve the quality of global analysis. It is shown that assimilating the 6-h averaged TMI rainfall and TPW retrievals improves not only the hydrological cycle, but also key climate parameters such as clouds, radiation, and the large-scale circulation produced by the Goddard Earth Observing System (GEOS) data assimilation system (DAS). Notably, assimilating TMI rain rates improves clouds and radiation in areas of active convection, as well as the latent heating distribution and the large-scale motion field in the Tropics, while assimilating TMI TPW retrievals leads to reduced moisture biases and improved radiative fluxes in clear-sky regions. Assimilating these data also improves the instantaneous wind and temperature fields in the analysis, leading to better short-range forecasts in the Tropics. Ensemble forecasts initialized with analyses incorporating TMI rain rates and TPW yield smaller biases in tropical precipitation forecasts beyond 1 day, better 500-hPa geopotential height forecasts up to 5 days, and better 200-hPa divergent winds up to 2 days. These results demonstrate the potential of using high quality spaceborne rainfall and moisture observations to improve the quality of assimilated global data for climate analysis and weather forecasting applications."
"7003406400;7006184606;","The vertical resolution sensitivity of simulated equilibrium temperature and water-vapour profiles",2000,"10.1002/qj.49712656502","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034130313&doi=10.1002%2fqj.49712656502&partnerID=40&md5=76b2c9adb5dd8a0dd7feee50abb107f3","Variability of atmospheric water vapour is the most important climate feedback in present climate models. Thus, it is of crucial importance to understand the sensitivity of water vapour to model attributes, such as physical parametrizations and resolution. Here we attempt to determine the minimum vertical resolution necessary for accurate prediction of water vapour. To address this issue, we have run two single-column models to tropical radiative-convective equilibrium states and have examined the sensitivity of the equilibrium profiles to vertical resolution. Both column models produce reasonable equilibrium states of temperature and moisture. Convergence of the profiles was achieved in both models using a uniform vertical resolution of around 25 hPa. Coarser resolution leads to significant errors in both the water vapour and temperature profiles, with a resolution of 100 hPa proving completely inadequate. However, fixing the boundary-layer resolution and altering only the free-tropospheric resolution significantly reduces sensitivity to vertical resolution in one of the column models, in both water and temperature, highlighting the importance of resolving boundary-layer processes. Additional experiments show that the height of the simulated tropopause is sensitive to upper-tropospheric vertical resolution. At resolutions higher than 33 hPa, one of the models developed a high degree of vertical structure in the vapour profile, resulting directly from the complex array of microphysical processes included in the stratiform cloud parametrization, some of which were only resolved at high resolutions. This structure was completely absent at lower resolutions, casting some doubt on the approach of using relatively complicated cloud schemes at low vertical resolutions."
"55837993200;24322005900;6602504047;7202746102;","Use of a neural-network-based long-wave radiative-transfer scheme in the ECMWF atmospheric model",2000,"10.1002/qj.49712656318","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034010152&doi=10.1002%2fqj.49712656318&partnerID=40&md5=d9bd506fc10c688a40ec040df1afa306","The definition of an approach for radiative-transfer modelling that would enable computation times suitable for climate studies and a satisfactory accuracy, has proved to be a challenge for modellers. A fast radiative-transfer model is tested at ECMWF: NeuroFlux. It is based on an artificial neural-network technique used in conjunction with a classical cloud approximation (the multilayer grey-body model). The accuracy of the method is assessed through code-by-code comparisons, climate simulations and ten-day forecasts with the ECMWF model. The accuracy of NeuroFlux appears to be comparable to the accuracy of the ECMWF operational scheme, with a negligible impact on the simulations, while its computing time is seven times faster."
"7003567733;36098762900;","Stabilization of Venus' climate by a chemical-albedo feedback",2000,"10.1186/BF03351628","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000033998&doi=10.1186%2fBF03351628&partnerID=40&md5=a209d208b3bd94b42b996d5105d466c7","It has been suggested that the atmospheric concentration of SO2 observed on Venus coincides with the equilibrium concentration over pyrite-magnetite assemblage (pyrite-magnetite buffer). If the atmospheric SO2 abundance is controlled by the chemical reaction at the planetary surface, we expect coupling between the atmospheric SO2 abundance and the surface temperature. Here, we propose that the pyrite-magnetite buffer combined with cloud albedo feedback controls the surface temperature on Venus. We show that this mechanism keeps the surface temperature in a rather narrow range around the presently observed value against large variations of solar luminosity and total atmospheric mass."
"7003338785;","Climatic patterns in a tropical rainforest in Brunei",2000,"10.1111/j.1475-4959.2000.tb00007.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033996808&doi=10.1111%2fj.1475-4959.2000.tb00007.x&partnerID=40&md5=3ae497ab9eaa5faf28840b2653c926cb","Meteorological parameters were monitored on an hourly basis over ten months during 1991-2, from altitudes of 45 and 913 metres in an undisturbed tropical rainforest in Brunei, near the north-west coast of Borneo. In general, the observed characteristics of the climate accorded with the regional meteorological systems and with published results from other studies in northern Borneo, although a greater degree of temporal variability was apparent. The seasonal variability was probably enhanced by the El Nino Southern Oscillation event of early 1992. Rainfall events were typically highly variable in nature, although storm intensity profiles were broadly similar. High magnitude and high intensity events are common among the large total number of events. More rain, of generally higher intensity, fell on the mountain. The total daily solar energy receipt was similar at both altitudes owing to greater cloud cover on the mountain. Temperatures varied significantly with season at both altitudes and the mean lapse rate was 4.5°C/km. Relative humidity at 913 metres tended to be significantly higher during the day and significantly lower at night than at 45 metres. Wind directions were dominantly controlled by local mountain and valley wind systems. Wind speeds were significantly higher during the dry seasons and at the higher altitude. Previous studies have shown that small but significant variations in meteorological parameters can have distinct ecological responses, and rainfall characteristics are important controls on geomorphological processes."
"12760994800;6601950693;7101603186;","The global fire product: Daily fire occurrence from april 1992 to december 1993 derived from NOAA AVHRR data",2000,"10.1080/014311600210173","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034655501&doi=10.1080%2f014311600210173&partnerID=40&md5=145c6868ae4ae2baa272db431e60fa0c","Global active fire maps have been produced over a 21-month period from April 1992 to December 1993. A contextual active fire detection algorithm has been applied to the NOAA AVHRR (National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer) 1.1 km images provided by the IGBP-DIS (International Geosphere-Biosphere Programme Data and Information System) 1 km AVHRR Global Land Project data set. The Global Fire Product (GFP) is composed of daily fire position tables, 10-day synthesis raster format maps containing fire density and cloud/no-data information; it is now available as the first global scale description of the spatial and temporal distribution of active vegetation fire. In answer to science community requirements the GFP supplies information which can be used to estimate fire impacts on atmospheric chemistry, climate, land use and land cover changes. © 2000 Taylor and Francis Ltd."
"57213483755;","Influence of meteorological conditions on the intensity and form of the urban heat island effect in Regina",2000,"10.1111/j.1541-0064.2000.tb00709.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034461035&doi=10.1111%2fj.1541-0064.2000.tb00709.x&partnerID=40&md5=bdb26f1bfb5574c5f11ab57eec009d5e","This study investigates the influence of meteorological conditions on the intensity and spatial configuration of the urban heat island effect in Regina, Saskatchewan. A sample of 31 nocturnal heat island intensities measured via automobile surveys averages 3°C, with a maximum intensity reaching 7.5°C. On nights with clear skies and light winds, heat island morphology in Regina is characterized by a clearly defined cliff, plateau, and peak. Regression analysis reveals that heat island intensities are highly sensitive to changes in wind conditions, and relatively insensitive to changes in humidity and atmospheric pressure. However, when antecedent weather conditions preceding each heat island event are included in the analysis, cloud cover supersedes wind speed as a more important control on heat island intensity. Daytime and post-sunset cloud cover explain 20 percent more variance in the ensuing nocturnal heat island intensities than do daytime and post-sunset wind speeds. This result challenges the widely-held notion that wind speed is a more important heat island control than sky cover."
"7202840464;6506703348;","Research for mountain area development: Climatic fluctuations in the mountains of the Americas and their significance",2000,"10.1579/0044-7447-29.7.364","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033708997&doi=10.1579%2f0044-7447-29.7.364&partnerID=40&md5=14edd4c632df2d2dad1c6f8726ffc23f","Twentieth century temperature trends in the Western Cordilleras of the Americas broadly reflect the global signal of warming and decreasing diunal temperature range. Precipitation changes are more modest and vary strongly with region. Mountain glaciers have retreated considerably since the Little Ice Age in response particularly to the temperature rise and an upward shift in tropical freezing level over the last three decades. The changes are already affecting hydrologic regimes. Potential negative ecological consequences for the cloud forest ecosystem have also been suggested. Andean agriculture might benefit, however, from an upward shift in the zone of frequent frosts."
"35584010200;7006432091;","The 1997 Pan American Climate Studies Tropical Eastern Pacific Process Study. Part I: ITCZ region",2000,"10.1175/1520-0477(2000)081<0451:TPACST>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000725846&doi=10.1175%2f1520-0477%282000%29081%3c0451%3aTPACST%3e2.3.CO%3b2&partnerID=40&md5=2d22283f39a727031e628a6c05d969da","The Pan American Climate Studies Tropical Eastern Pacific Process Study (TEPPS) obtained a comprehensive set of observations of the structure of clouds and precipitating storms over the eastern tropical Pacific from 28 July to 6 September 1997. The TEPPS data can address a wide range of problems involving tropical oceanic clouds and precipitation. The main goal of the project was to understand why passive microwave satellite algorithms indicate an E-W gradient in the precipitation pattern in the tropical Pacific with heavier rainfall in the east while infrared satellite algorithms indicate heavier rainfall in the west. Satellite-derived precipitation estimates are based on characteristics of the vertical structure of precipitating clouds: in the case of infrared methods, cloud-top temperature, and in the case of microwave methods, the vertically integrated ice scattering and/or water absorption determined by the vertical profile of hydrometeors. The premise of the expedition was that by obtaining surface-based radar measurements of the vertical structure of precipitation where and when the differences between the infrared and microwave precipitation estimates were large, it could be determined which satellite method yielded a more accurate pattern of precipitation in the Pacific. This paper describes the types of observations obtained during TEPPS and some preliminary results. A single, well-equipped vessel on its maiden voyage, the National Oceanic and Atmospheric Administration ship Ronald H. Brown, was the base for all observations. Scanning C-band Doppler radar and cloud photography documented the three-dimensional structure of clouds and precipitation in the vicinity of the ship. Upper-air soundings were obtained at ≤ 4 h intervals. Surface meteorological and oceanographic instruments and vertically pointing 915-MHz and S-band profilers characterized conditions at the ship itself. During 28.5 days in the eastern Pacific ITCZ, the shipborne radar observed echoes larger than 50 km in maximum horizontal dimension within 100-km radius of the ship 71% of the time and larger than 100 km 55% of the time. The ship spent 16 days on station at 7.8°N, 125°W and 4 days in the vicinity of Hurricane Guillermo. Samples of surface atmospheric and oceanic data collected during the cruise illustrate the difficulty of interpreting short timescale buoy data time series in the absence of the mesoscale context provided by radar data. The ship sounding data show that the larger-scale, longer-lived convective precipitation activity and organization on timescales of days in the eastern Pacific ITCZ is closely associated with the presence of stronger southerly winds, which in turn suggests that large-scale atmospheric processes such as easterly waves or inertial stability oscillations are a regulating mechanism. Comparison of the ship radar data, satellite IR data, and satellite microwave data shows that part of the reason why the IR and microwave-derived precipitation maps differ is that in the eastern Pacific ITCZ IR cold cloudiness resolves only a subset of the precipitation detected by microwave data. Large precipitating systems (> 100 km scale) of long duration (> 24 h; i.e., the mesoscale organized systems) were reliably associated with cold cloudiness < 235 K. Precipitating systems of shorter duration and/or smaller scale (i.e., the less-organized convection) sometimes reached 235 K and sometimes did not. Satellite microwave data generally agreed with the radar data regarding the location and areal coverage of precipitating regions larger than ∼10 km in horizontal scale. However, the microwave algorithm examined in this study had varying degrees of skill in locating the heavier rainfall areas within rainy regions."
"8762684000;7007026915;7005050002;7005784518;","A satellite-based climatic description of jet aircraft contrails and associations with atmospheric conditions, 1977-79",2000,"10.1175/1520-0450(2000)039<1434:ASBCDO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033730306&doi=10.1175%2f1520-0450%282000%29039%3c1434%3aASBCDO%3e2.0.CO%3b2&partnerID=40&md5=02ada72b657effc5b94fe5097dd11540","The possible contribution of jet aircraft condensation trails (contrails) to recent observed increases in high cloudiness constitutes a potentially important human effect on climate that has received relatively little attention. Very high resolution (0.6 km) thermal-infrared imagery from the Defense Meteorological Satellite Program polar orbiters, concentrated in the nighttime and morning hours, is interpreted to derive a climatic description of contrails over the United States and adjacent areas for the midseason months (April, July, October, and January) of 1977-79. A manual technique of identifying contrails on the imagery is validated by comparison with more recent ground-based observations. Contrail spatial distributions are mapped at a 1° lat × 1° long resolution for monthly and multimonth time periods. Contrail incidence is widespread over the United States and adjacent areas, with highest frequencies occurring over the following regions: the extreme Southwest (particularly southern California), the Southeast (especially southeast Georgia and northeast Florida), the west coast of British Columbia and Vancouver Island, and the eastern Midwest centered on southeast Indiana and western Kentucky. Contrails are most frequent during the transition-season months (April and October), and are least frequent in July. Latitudinally, contrail incidence peaks over the northern (southern) regions in July (January), suggesting a first-order association with the seasonal variation of upper-tropospheric westerly winds. Analysis of synoptic-scale midtropospheric circulation patterns confirms that the highest contrail frequencies occur in association with baroclinic phenomena, particularly cyclone waves and jet streams. Moreover, contrails tend frequently to occur in conjunction with other clouds, including the cirrus associated with jet-stream and frontal systems. Analyses of rawinsonde data for three representative contrail ""outbreak"" (multiple occurrence) events during the study months confirm some earlier studies that suggest contrails form below a cold, elevated tropopause (i.e., around ridgelines in the geopotential height field), in contrast with noncontrail days. Accordingly, the temperature advection in the troposphere accompanying the contrail outbreaks is positive, or warm, and relatively weak. This contrail climatic description provides a context within which recent surface climate changes at regional and subregional scales may be cast."
"56455165800;7003440089;","A sensitivity study of the subtropical ocean surface energy balance to the parameterization of precipitation from stratocumulus clouds",2000,"10.1023/A:1002482230580","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034029273&doi=10.1023%2fA%3a1002482230580&partnerID=40&md5=aa35f4ad70955eb6adafa55852dc3037","In the 'First Lagrangian' of the Atlantic Stratocumulus Experiment (ASTEX), a cloudy air mass was tracked as it was advected by the trade winds toward higher sea surface temperatures. In this study, a full diurnal cycle observed during this experiment is simulated and the impact of the precipitation parameterization is examined. The model we use is the one dimensional version of the hydrostatic primitive equation model MAR (Modele Atmospherique Regional) developed at the Universite catholique de Louvain (UCL). It includes an E-ε turbulence closure, a wide-band formulation of the radiative transfer, and a parameterized microphysical scheme allowing partial condensation. The model realistically reproduces the diurnal clearing of the cloud layer as well as the formation of cumulus clouds under the stratocumulus deck. Nevertheless, as the surface warms and the boundary layer becomes more convective, the simulation progressively differs from the observed evolution. Further experiments are carried out with different precipitation parameterizations commonly used in mesoscale models and general circulation models (GCMs). A strong sensitivity of the simulated liquid water path evolution is found. The impact on the surface energy flux and the solar flux reflected by the cloud is also examined. For both fluxes averaged over 24 hours, differences as large as 20 W m-2 are obtained between the various simulations. Low cloudiness covers large areas over the ocean and such errors on the reflected solar flux may strongly affect the Earth's radiative budget in GCM simulations. We estimate that the impact on the globally averaged outgoing solar flux could be as large as 5 W m-2. Furthermore, when atmospheric models are coupled to ocean models, errors in the surface energy exchanges may induce significant drift in the simulated climate."
"36127012800;7005449794;","Modeling the biosphere-atmosphere system: The impact of the subgrid variability in rainfall interception",2000,"10.1175/1520-0442(2000)013<2887:MTBAST>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253121&doi=10.1175%2f1520-0442%282000%29013%3c2887%3aMTBAST%3e2.0.CO%3b2&partnerID=40&md5=85b49b404e09175b5c3d08e800643d9b","Subgrid variability in rainfall distribution has been widely recognized as an important factor to include in the representation of land surface hydrology within climate models. In this paper, using West Africa as a case study, the impact of the subgrid variability in rainfall interception on the modeling of the biosphere-atmosphere system is investigated. According to the authors' results, when neglecting the rainfall spatial variability, even if the impact on the total evapotranspiration is negligible, significant errors may result in the representation of surface hydrological processes and surface energy balance. These findings are consistent with the results of previous studies. However, in this paper, this issue is further explored and it is demonstrated that the extent of the resulting errors is not limited to the land surface processes. They extend to the atmosphere via the low-level cloud feedback to impact solar radiation, boundary layer energy, atmospheric circulation, and the distribution of precipitation. The same errors also propagate into the biosphere through vegetation dynamics and can eventually lead to a significantly different biosphere-atmosphere equilibrium state. This study provides a good example for the need to have physical realism in modeling the subgrid variability and most other details of the complex biosphere-atmosphere-ocean system.Subgrid variability in rainfall distribution has been widely recognized as an important factor to include in the representation of land surface hydrology within climate models. In this paper, using West Africa as a case study, the impact of the subgrid variability in rainfall interception on the modeling of the biosphere-atmosphere system is investigated. According to the authors' results, when neglecting the rainfall spatial variability, even if the impact on the total evapotranspiration is negligible, significant errors may result in the representation of surface hydrological processes and surface energy balance. These findings are consistent with the results of previous studies. However, in this paper, this issue is further explored and it is demonstrated that the extent of the resulting errors is not limited to the land surface processes. They extend to the atmosphere via the low-level cloud feedback to impact solar radiation, boundary layer energy, atmospheric circulation, and the distribution of precipitation. The same errors also propagate into the biosphere through vegetation dynamics and can eventually lead to a significantly different biosphere-atmosphere equilibrium state. This study provides a good example for the need to have physical realism in modeling the subgrid variability and most other details of the complex biosphere-atmosphere-ocean system."
"6602425844;7005126327;","Calibration of a photometric cloud condensation nucleus counter designed for deployment on a balloon package",2000,"10.1175/1520-0426(2000)017<0459:COAPCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034091236&doi=10.1175%2f1520-0426%282000%29017%3c0459%3aCOAPCC%3e2.0.CO%3b2&partnerID=40&md5=ada4609916be0d36dba4b59a8e1b1ad4","The importance of atmospheric aerosols in understanding global climate changes has renewed interest in measurements of cloud condensation nuclei (CCN). To obtain high-resolution (125 m) vertical profiles of CCN number concentration, a balloon-borne instrument was developed. The instrument deduces the CCN concentration from measurements of laser light scattered by water droplets that condense on CCN within a static thermal-gradient diffusion chamber. The amount of light scattering is linearly proportional to the number of droplets within the different chamber. Correlating the number of droplets within the sample volume with the amount of light scattered by the droplets provides the calibration constant that relates scattered light to CCN concentration. The calibration was tested by comparisons between the CCN counter and a condensation nuclei counter when sampling monodisperse aerosol larger than the CCN counter's critical activation size. The calibration constant depends on supersaturation, and depends slightly on the size of CCN that activate to form droplets. For dry NaCl aerosol between 35 and 160 nm, the calibration constant varies by less than 10% at 1% supersaturation. Calibration on ambient atmospheric aerosol is similar to calibration on laboratory-generated polydisperse NaCl aerosol, which indicates that the laboratory calibration can be applied to field measurements. During field and laboratory measurements, the time required for the activation and growth of droplets within the diffusion chamber is similar. Overall, the uncertainty of the calibration constant for the balloon-borne CCN counter is approximately 10% at 1% supersaturation."
"7402717381;7003376335;7402584677;","On the characteristics of the water cycle of the Mackenzie River Basin",2000,"10.1127/metz/9/2000/103","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001058244&doi=10.1127%2fmetz%2f9%2f2000%2f103&partnerID=40&md5=e4030dd6471f3318f18f0414493269ce","This study is concerned with the water cycle of the Mackenzie River Basin of northwestern Canada. The analysis of water vapour, clouds, precipitation, snow cover, discharge and temperature shows that the region is subject to substantial interannual variability and strong seasonal cycles. A number of processes unique to cold climate regions, such as the impacts of various precipitation types, affect the water cycle of the basin. As well, this basin is experiencing a strong warming trend that is linked with an enhancement of some water variables, and an apparent reduction in atmospheric recycling. The Mackenzie Basin also exhibits some overall characteristics which differ from other high latitude regions due to its unique geography. © Gebrüder Borntraeger, Berlin, Stuttgart 2000."
"7006957668;6603244291;7402942478;7409376438;57202803751;35425197200;7101600167;7004114883;","Assimilation of SSM/I-derived surface rainfall and total precipitable water for improving the GEOS analysis for climate studies",2000,"10.1175/1520-0493(2000)128<0509:AOSIDS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034014765&doi=10.1175%2f1520-0493%282000%29128%3c0509%3aAOSIDS%3e2.0.CO%3b2&partnerID=40&md5=1fd7e7e393c87a291147d73091fc4324","This article describes a variational framework for assimilating the SSM/I-derived surface rain rate and total precipitable water (TPW) and examines their impact on the analysis produced by the Goddard Earth Observing System (GEOS) Data Assimilation System (DAS). The SSM/I observations consist of tropical rain rates retrieved using the Goddard Profiling Algorithm and tropical TPW estimates produced by Wentz. In a series of assimilation experiments for December 1992. results show that the SSM/I-derived rain rate, despite current uncertainty in its intensity, is better than the model-generated precipitation. Assimilating rainfall data improves cloud distributions and the cloudy-sky radiation, while assimilating TPW data reduces a moisture bias in the lower troposphere to improve the clear-sky radiation. Together, the two data types reduce the monthly mean spatial bias by 46% and the error standard deviation by 26% in the outgoing longwave radiation (OLR) averaged over the Tropics, as compared with the NOAA OLR observation product. The improved cloud distribution, in turn, improves the solar radiation at the surface. There is also evidence that the latent heating change associated with the improved precipitation improves the large-scale circulation in the Tropics. This is inferred from a comparison of the clear-sky brightness temperatures for TIROS Operational Vertical Sounder channel 12 computed from the GEOS analyses with the observed values, suggesting that rainfall assimilation reduces a prevailing moist bias in the upper-tropospheric humidity in the GEOS system through enhanced subsidence between the major convective centers. This work shows that assimilation of satellite-derived precipitation and TPW can reduce state-dependent systematic errors in the OLR, clouds, surface radiation, and the large-scale circulation in the assimilated dataset. The improved analysis also leads to better short-range forecasts, but the impact is modest compared with improvements in the time-averaged signals in the analysis. The study shows that, in the presence of biases and other errors of the forecast model, it is possible to improve the time-averaged ""climate contentin the data without comparable improvements in forecast. The full impact of these data types on the analysis cannot be measured solely in terms of forecast skills."
"6507370012;7403263977;","The excitation of equatorial waves by deep convection in the NCAR Community Climate Model (CCM3)",2000,"10.1175/1520-0469(2000)057<3461:TEOEWB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034319060&doi=10.1175%2f1520-0469%282000%29057%3c3461%3aTEOEWB%3e2.0.CO%3b2&partnerID=40&md5=0bbdaf97562656de6f8e09a900bb1b67","The forcing of equatorial waves by convective heating in the National Center for Atmospheric Research Community Climate Model (CCM3) is investigated and compared with the forcing deduced from observations of convective clouds. The analysis is performed on two different simulations, wherein convection is represented by the Zhang-McFarlane and the Hack parameterization schemes, respectively. Spectra of equatorial waves excited by convective heating (Rossby, Kelvin, and gravity waves) are obtained by projecting the heating field onto Hough modes; the dynamical response to the heating is then calculated in terms of the vertical component of the Eliassen-Palm flux, Fz, focusing on waves that are able to propagate into the middle atmosphere. The same analysis is repeated using observations of outgoing longwave radiation as a proxy for tropical convection. Comparison of CCM3 results with those derived from observations indicates that high-frequency heating variability is underestimated in both CCM3 simulations, despite the fact that time-mean values of convective heating are well represented. Moreover, the two convective parameterization schemes differ substantially from each other: Compared to observations, Fz is severely underestimated at most frequencies when CCM3 is run with the Zhang-McFarlane scheme. When the Hack scheme is used, Fz at frequencies |ω| &lt; 0.5 cycles per day is comparable to the observations, but it is underestimated at higher frequencies. Misrepresentation of the variability of convective heating is likely to have important consequences for the dynamical simulation of the middle atmosphere and even the troposphere.The forcing of equatorial waves by convective heating in the National Center for Atmospheric Research Community Climate Model (CCM3) is investigated and compared with the forcing deduced from observations of convective clouds. The analysis is performed on two different simulations, wherein convection is represented by the Zhang-McFarlane and the Hack parameterization schemes, respectively. Spectra of equatorial waves excited by convective heating (Rossby, Kelvin, and gravity waves) are obtained by projecting the heating field onto Hough modes; the dynamical response to the heating is then calculated in terms of the vertical component of the Eliassen-Palm flux, Fz, focusing on waves that are able to propagate into the middle atmosphere. The same analysis is repeated using observations of outgoing longwave radiation as a proxy for tropical convection. Comparison of CCM3 results with those derived from observations indicates that high-frequency heating variability is underestimated in both CCM3 simulations, despite the fact that time-mean values of convective heating are well represented. Moreover, the two convective parameterization schemes differ substantially from each other: Compared to observations, Fz is severely underestimated at most frequencies when CCM3 is run with the Zhang-McFarlane scheme. When the Hack scheme is used, Fz at frequencies |ωVBAR &lt; 0.5 cycles per day is comparable to the observations, but it is underestimated at higher frequencies. Misrepresentation of the variability of convective heating is likely to have important consequences for the dynamical simulation of the middle atmosphere and even the troposphere."
"7006977548;7005188866;","Volcanic winter in the Garden of Eden: The Toba supereruption and the late Pleistocene human population crash",2000,"10.1130/0-8137-2345-0.71","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870949589&doi=10.1130%2f0-8137-2345-0.71&partnerID=40&md5=7de3b5c9c5a3ed1f8e60f0a915be02b0","The Toba eruption (ca. 73,500 B.P., Indonesia) was the largest explosive eruption of the last few hundred thousand years. Several lines of evidence suggest that Toba produced an estimated 1015-1016 g of stratospheric dust and H2SO4 aerosols, and ice-core data and atmospheric modeling indicate a ca. 6-yr residence time for the dense global aerosol cloud. Such a stratospheric aerosol loading is predicted to have caused a ""volcanic winter"" with possible abrupt regional coolings of up to 15° C (similar to nuclear winter scenarios), and global cooling of 3-5° C (and possibly greater) for several years. Ice-core data suggest that Toba may have contributed to the initial severe cooling of a millennium-long cold event, suggesting involvement of climate feedback responses such as ocean cooling, and increased sea ice and snow cover. Botanical studies and model simulations suggest that the local and regional effects of the predicted post-Toba cooling would have been disastrous for vegetation. Cold-sensitive tropical vegetation would have been almost totally destroyed, and the predicted reduction of early growing-season temperatures by ≥10° C in higher latitudes could have killed most temperate and subarctic forests, with surviving vegetation severely damaged and recovery times taking decades. Global climate models predict that the Toba atmospheric perturbation would have caused severe drought in the tropical rainforest belt and in monsoonal regions. These results constitute a global ecological disaster, with expected reductions in standing crops of plants and animals especially in the tropics. Evidence for these abrupt environmental changes may be detectable in high-resolution palynological records, coral reefs, and ice cores. Genetic studies indicate that sometime prior to ca. 60,000 yr ago humans suffered a severe population bottleneck (possibly only 3,000-10,000 individuals), followed eventually by rapid population increase, technological innovations, and migrations. The climatic effects of the paroxysmal Toba eruption could have caused the bottleneck, and the event might have been a catalyst for the technological innovations and migrations that followed. The present results as to the predicted environmental and ecological effects of the eruption lend support to a possible connection between the Toba event and the human population bottleneck, and suggest that similar bottlenecks among other organisms might be expected at about the same time. Some chimpanzee populations appear to have undergone such a bottleneck ca. 70,000-60,000 yr ago."
"7401776640;7402064802;","Low cloud type over the ocean from surface observations. Part III: Relationship to vertical motion and the regional surface synoptic environment",2000,"10.1175/1520-0442(2000)013<0245:LCTOTO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034072364&doi=10.1175%2f1520-0442%282000%29013%3c0245%3aLCTOTO%3e2.0.CO%3b2&partnerID=40&md5=f93204366bbfa1d00669554077ee41b8","Composite large-scale dynamical fields contemporaneous with low cloud types observed at midlatitude Ocean Weather Station (OWS) C and eastern subtropical OWS N are used to establish representative relationships between low cloud type and the synoptic environment. The composites are constructed by averaging meteorological observations of surface wind and sea level pressure from volunteering observing ships (VOS) and analyses of sea level pressure, 1000-mb wind, and 700-mb pressure vertical velocity from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis project on those dates and times of day when a particular low cloud type was reported at the OWS. VOS and NCEP results for OWS C during summer show that bad-weather stratus occurs with strong convergence and ascent slightly ahead of a surface low center and trough. Cumulus-under-stratocumulus and moderate and large cumulus occur with divergence and subsidence in the cold sector of an extratropical cyclone. Both sky-obscuring fog and no-low-cloud typically occur with southwesterly flow from regions of warmer sea surface temperature and differ primarily according to slight surface convergence and stronger warm advection in the case of sky-obscuring fog or surface divergence and weaker warm advection in the case of no-low-cloud. Fair-weather stratus and ordinary stratocumulus are associated with a mixture of meteorological conditions, but differ with respect to vertical motion in the environment. Fair-weather stratus occurs most commonly in the presence of slight convergence and ascent, while stratocumulus often occurs in the presence of divergence and subsidence. Surface divergence and estimated subsidence at the top of the boundary layer are calculated from VOS observations. At both OWS C and OWS N during summer and winter these values are large for ordinary stratocumulus, less for cumulus-under-stratocumulus, and least (and sometimes slightly negative) for moderate and large cumulus. Subsidence interpolated from NCEP analyses to the top of the boundary layer does not exhibit such variation, but the discrepancy may be due to deficiencies in the analysis procedure or the boundary layer parameterization of the NCEP model. The VOS results suggest that decreasing divergence and subsidence in addition to increasing sea surface temperature may promote the transition from stratocumulus to trade cumulus observed over low-latitude oceans.Composite large-scale dynamical fields contemparoneous with low cloud types observed at midlatitude Ocean Weather Station (OWS) C and eastern subtropical OWS N are used to establish representative relationships between low cloud type and the synoptic environment. The composites are constructed by averaging meteorological observations of surface wind and sea level pressure from volunteering observing ships (VOS) and analyses of sea level pressure, 1000-mb wind, and 700-mb pressure vertical velocity from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis project on those dates and times of day when a particular low cloud type was reported at the OWS. VOS and NCEP results for OWS C during summer show that bad-weather stratus occurs with strong convergence and ascent slightly ahead of a surface low center and trough. Cumulus-under-stratocumulus and moderate and large cumulus occur with divergence and subsidence in the cold sector of an extratropical cyclone. Both sky-obscuring fog and no-low-cloud typically occur with southwesterly flow from regions of warmer sea surface temperature and differ primarily according to slight surface convergence and stronger warm advection in the case of sky-obscuring fog or surface divergence and weaker warm advection in the case of no-low-cloud. Fair-weather stratus and ordinary stratocumulus are associated with a mixture of meteorological conditions, but differ with respect to vertical motion in the environment. Fair-weather stratus occurs most commonly in the presence of slight convergence and ascent, while stratocumulus often occurs in the presence of divergence and subsidence. Surface divergence and estimated subsidence at the top of the boundary layer are calculated from VOS observations. At both OWS C and OWS N during summer and winter these values are large for ordinary stratocumulus, less for cumulus-under-stratocumulus, and least (and sometimes slightly negative) for moderate and large cumulus. Subsidence interpolated from NCEP analyses to the top of the boundary layer does not exhibit such variation, but the discrepancy may be due to deficiencies in the analysis procedure or the boundary layer parameterization of the NCEP model. The VOS results suggest that decreasing divergence and subsidence in addition to increasing sea surface temperature may promote the transition from stratocumulus to trade cumulus observed over low-latitude oceans."
"56261366000;","Palaeoclimatic interpretation of clay minerals in marine deposits: An outlook from the continental origin",2000,"10.1016/S0012-8252(99)00054-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034070891&doi=10.1016%2fS0012-8252%2899%2900054-9&partnerID=40&md5=91071cf34dcd04db46ce7209a561b07e","As distribution of clay minerals in modern oceans seems to be controlled by contemporary climates, marine clays in ancient deposits have been widely used to reconstruct palaeoclimates. In this review, we examine this question mainly from the continental origin of the clay minerals and show the difficulties of retrospective analysis of the influence of climate on common marine deposits. We examine successively how soils develop and behave, are reworked and palaeoweatherings are preserved, focusing the review on kaolinitic soils indicative of tropical wet climates. Several stages intervene between the time of clay mineral development in soils and their final deposition in the basin: (1) The persistence over geological times of huge amounts of kaolinitic palaeoweathering materials in the landscapes may seriously alter the palaeoclimatic signal of kaolinite in the sedimentary record. Although the kaolinite deposited in recent sediments of the world oceans is consistent with wet climatic zones, this is mainly because the major kaolinitic and bauxitic palaeosurfaces coincide with the tropical areas where kaolinite is still developing at present. (2) Possible development of deep kaolinitic profiles at high latitudes and cold conditions, under CO2-enriched palaeoatmospheres, or even by unusual acidic weathering linked with dry climates is misleading palaeoenvironments for palaeoclimatic reconstruction. (3) Erosion and transport processes always cloud the signal to some extent, because frequently, erosion products from the bedrock and different soil horizons will be mixed and major drainage systems may include soils of different climatic zones. (4) The arrival of the soil clay assemblages in the basin inevitably lags against their formation on the continent and may occur several million years after formation of the soils on the continent and climate may have considerably changed at that time. It is pointed out that sedimentologists and palaeoclimatologists should consider the complexity of the relations between soil and sedimentary clay minerals. Soil formation rates are slow and therefore the resolution of the palaeoclimatic record in marine clay may not be closer than 1 or 2 Ma. At present, the palaeoclimatic interpretations of marine clay assemblages are yielding, at best, nothing more than rather broad palaeoclimatic information. This approach cannot achieve the same degree of resolution as other techniques such as isotope or microfossil studies. Clay mineral assemblages may provide integrated records of overall climatic impacts, whereas other techniques are more likely to reveal local or temporary climates. © 2000 Elsevier Science B.V. All rights reserved."
"7102301816;57209147154;7005685786;","The Madden-Julian oscillation observed during the TOGA COARE IOP: Global view",2000,"10.1175/1520-0469(2000)057<2374:TMJOOD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253372&doi=10.1175%2f1520-0469%282000%29057%3c2374%3aTMJOOD%3e2.0.CO%3b2&partnerID=40&md5=80d28d4afc7378ea23c8804f4ddfddb7","During the TOGA COARE Intensive Observing Period (November 1992-February 1993), two pronounced Madden-Julian oscillation (MJO) events associated with super cloud clusters and westerly wind bursts were observed. This paper presents a global view of the MJOs including the origin of the super clusters in the Indian Ocean, their migration into the Maritime Continent and the TOGA COARE large-scale soundings array (LSA) in the western equatorial Pacific, and their rapid decay over cold water of the eastern Pacific. The structure and evolution of the MJO are examined with emphasis on the coupling between large-scale motion and convection. Because of differences in propagation speeds, the positions of maximum zonal wind perturbations relative to deep convection undergo systematic changes during the travel of the MJO. However, the centers of deep convection always coincide with those of large-scale ascent. The super cloud cluster accompanies a wide area of warm air in the upper troposphere. Over the warm pool region the perturbation kinetic energy of the motion in the 30-60-day period range is maintained by the conversion of perturbation available potential energy generated by convective heating. Over the central-eastern Pacific, there is strong horizontal convergence of wave energy flux entering the equatorial upper-tropospheric westerly duct from the extratropical latitudes, suggesting interactions of the MJO with midlatitude disturbances.During the TOGA COARE Intensive Observing Period (November 1992-February 1993), two pronounced Madden-Julian oscillation (MJO) events associated with super cloud clusters and westerly wind bursts were observed. This paper presents a global view of the MJOs including the origin of the super clusters in the Indian Ocean, their migration into the Maritime Continent and the TOGA COARE large-scale soundings array (LSA) in the western equatorial Pacific, and their rapid decay over cold water of the eastern Pacific. The structure and evolution of the MJO are examined with emphasis on the coupling between large-scale motion and convection. Because of differences in propagation speeds, the positions of maximum zonal wind perturbations relative to deep convection undergo systematic changes during the travel of the MJO. However, the centers of deep convection always coincide with those of large-scale ascent. The super cloud cluster accompanies a wide area of warm air in the upper troposphere. Over the warm pool region the perturbation kinetic energy of the motion in the 30-60-day period range is maintained by the conversion of perturbation available potential energy generated by convective heating. Over the central-eastern Pacific, there is strong horizontal convergence of wave energy flux entering the equatorial upper-tropospheric westerly duct from the extratropical latitudes, suggesting interactions of the MJO with midlatitude disturbances."
"7102936448;","Capture rates of electrons and positive ions by mesospheric aerosol particles",2000,"10.1016/S0021-8502(00)00030-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034333772&doi=10.1016%2fS0021-8502%2800%2900030-6&partnerID=40&md5=43b8df60ad5b2cda1dcd5ff06d7ea36f","Aerosol particles exist in the vicinity of the extremely cold polar summer mesopause and can be visually observed in the form of noctilucent clouds. Being embedded into the plasma of the D-region, these particles become charged by means of plasma diffusion and lead to huge VHF radar echoes known as Polar Mesospheric Summer Echoes. The diffusional charging of submicron particles has been treated in detail by Natanson and with some modifications by Fuchs. Previous model investigations of the charging of mesospheric aerosol particles applied analytical approximations to the rigorous Natanson theory which Natanson (1960) had derived for the case that the mean free path of the ions, λ, is much larger than the radius of the particles, rA. This conditions is satisfied for particles around the mesopause where λ to approximately 1 cm and rA≤100 nm. The aim of this note is to investigate the applicability of Natanson's analytical approximations for models of mesospheric aerosol particles.Aerosol particles exist in the vicinity of the extremely cold polar summer mesopause and can be visually observed in the form of noctilucent clouds (Jesse (1885) Met. Zeit. 2, 311-312). Being embedded into the plasma of the D-region, these particles become charged by means of plasma diffusion and lead to huge VHF radar echoes known as Polar Mesospheric Summer Echoes (Ecklund and Balsley (1981) J. Geophys. Res. 86, 7775-7780). The diffusional charging of submicron particles has been treated in detail by Natanson (1960, Sov. Phys. Tech. Phys. 5, 538-551) and with some modifications by Fuchs (1963, Geophys. Pura. Appl. 56, 185-193). Previous model investigations of the charging of mesospheric aerosol particles (e.g., Rapp and Lubken (1999) Earth Planets Space 51, 799-807) applied analytical approximations to the rigorous Natanson theory which Natanson (1960) had derived for the case that the mean free path of the ions, λ, is much larger than the radius of the particles, r(A). This conditions is satisfied for particles around the mesopause where λ~1cm and r(A)≤100nm (Thomas and Mc Kay (1985) Planet. Space Sci. 33 1209-1244). The aim of this note is to investigate the applicability of Natanson's analytical approximations for models of mesospheric aerosol particles. Copyright (C) 2000 Elsevier Science B.V."
"7005648708;7005561168;7006919060;8571512400;7006689582;56879243400;6603125636;","Analysis of water and heat balance components in the Lake Ladoga watershed as computed by atmospheric general circulation models",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033832021&partnerID=40&md5=07381175ebeb04fd4b7b3d967731f1cf","The annual cycle of the components of the water and heat balances in the Lake Ladoga watershed is analyzed using outputs of 14 atmospheric general circulation models run in the framework of the international Atmospheric Model Intercomparison Project (AMIP). The model results are compared with observational data. The surface air temperature, short- and long-wave surface radiation balances, total cloud cover, precipitation, and water balance (precipitation minus evaporation) are considered for the lake and its watershed. The rms errors in the annual cycles of the water-balance components and their seasonal and interannual variability are estimated for each model. The simulated and observed data, accumulated throughout 1980-1988, agree within 20-30%."
"8132205000;57203054708;","Empirical determination of the basic modes of cumulus heating and drying profiles",2000,"10.1175/1520-0469(2000)057<3571:EDOTBM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034318969&doi=10.1175%2f1520-0469%282000%29057%3c3571%3aEDOTBM%3e2.0.CO%3b2&partnerID=40&md5=655a0e2348a95be7cfd28a0e778f1774","The constraint on the coupled vertical profiles of cumulus heating and drying, which can be used as a partial closure in cumulus parameterization, is examined using observational data from convectively active regions in the summertime. The data used in this study include those derived from Global Atmospheric Research Programme (GARP) Atlantic Tropical Experiment Phase III, Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment over the intensive flux array region, and four subsets of the European Centre for Medium-Range Weather Forecasts Re-Analysis data that cover areas ranging from tropical to midlatitude continents. The profiles of Q1 and Q2 calculated from those data are analyzed using a statistical method. The proposed method is a revised version of the rotated principal component analysis based on the Promax rotation (RPCAPromax), which is believed suitable for identifying basic structures embedded within a given dataset. It is designed in such a way that the distortion of identified structures due to the use of a linear model is minimized. The revised RPCAPromax, together with some selected statistical tools, are evaluated using synthetic datasets before they are applied to observations. The analysis of the observational data shows that, for all the convectively active regions examined, most of the variance of observed Q1 and Q2 can be explained by retaining only two modes. Moreover, while these two modes have different amplitudes in time and space, the shapes of the Q1 and Q2 profiles associated with each mode are similar from one region to another. In this sense, they are analogous to the cloud types in the spectral cumulus ensemble model of the Arakawa-Schubert cumulus parameterization, in which the spectral distribution of cloud-base mass flux varies with large-scale conditions while the vertical profile of normalized mass flux is fixed for each cloud type. It is suggested that, as far as deep convection is concerned, the cloud model in cumulus parameterization probably can be constructed based on the empirically determined Q1 and Q2 profiles.The constraint on the coupled vertical profiles of cumulus heating and drying, which can be used as a partial closure in cumulus parameterization, is examined using observational data from convectively active regions in the summertime. The data used in this study include those derived from Global Atmospheric Research Programme (GARP) Atlantic Tropical Experiment Phase III, Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment over the intensive flux array region, and four subsets of the European Centre for Medium-Range Weather Forecasts Re-Analysis data that cover areas ranging from tropical to midlatitude continents. The profiles of Q1 and Q2 calculated from those data are analyzed using a statistical method. The proposed method is a revised version of the rotated principal component analysis based on the Promax rotation (RPCAPromax), which is believed suitable for identifying basic structures embedded within a given dataset. It is designed in such a way that the distortion of identified structures due to the use of a linear model is minimized. The revised RPCAPromax, together with some selected statistical tools, are evaluated using synthetic datasets before they are applied to observations. The analysis of the observational data shows that, for all the convectively active regions examined, most of the variance of observed Q1 and Q2 can be explained by retaining only two modes. Moreover, while these two modes have different amplitudes in time and space, the shapes of the Q1 and Q2 profiles associated with each mode are similar from one region to another. In this sense, they are analogous to the cloud types in the spectral cumulus ensemble model of the Arakawa-Schubert cumulus parameterization, in which the spectral distribution of cloud-base mass flux varies with large-scale conditions while the vertical profile of normalized mass flux is fixed for each cloud type. It is suggested that, as far as deep convection is concerned, the cloud model in cumulus parameterization probably can be constructed based on the empirically determined Q1 and Q2 profiles."
"6507253351;7102011703;7005453346;","The simulated response of the climate system to changes in soil moisture parameterization under paleoclimatic boundary conditions at 6000 years before present",2000,"10.1139/e99-104","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033863636&doi=10.1139%2fe99-104&partnerID=40&md5=c1b7c141555fa75dbce1b8cbf794e9a8","We present the results of a sensitivity study involving modifications to the simple land surface scheme implemented in the second-generation atmospheric general circulation model (GCMII) of the Canadian Climate Centre for Modelling and Analysis (CCCma), under paleoclimatic boundary conditions characteristic of 6000 calendar years before present (6 ka BP). The land surface parameterization is modified in two primary respects. Firstly, we modify the space dependant bucket depth scheme in the original model to one in which this depth is taken to be constant. Secondly, we modify the evapotranspiration parameterization from the space dependant form employed in the control model to a more conventional space independent scheme. In all, 4 experiments have been performed to enable us to resolve both the modern control and the 6 ka BP response to the land surface modifications. A subset of these simulations is also compared with results obtained using other models in the context of the Paleoclimate Model Intercomparison Project (PMIP) to investigate the mid-latitude behaviour of these models to reveal the extent to which model response to a change in radiative forcing may be significantly influenced by changes in the land surface parameterization. These comparisons reveal that the original Canadian GCMII model is an extreme outlier among the members of the set of all models in that its Northern Hemisphere mid-latitude surface continental response to the 6 ka BP insolation anomaly is significantly cold biased in the summer season. We investigate the extent to which this anomalous behaviour may be explained as a consequence of modifications to the land surface parameterizations employed in GCMII. Our results reveal a strong sensitivity in the modern control model to changes in bucket depth, but not to the modification of the evapotranspiration scheme. More interesting, however, is the fact that the model climate sensitivity at 6 ka BP is influenced both by changes in bucket depth and by changes in the evapotranspiration scheme. A detailed investigation of the surface energy balance, cloud cover, surface albedo, and snow cover reveals the role of each of the components that contribute to the 6 ka BP surface temperature response. Comparison of the predictions of the CCCma model with proxy climate indicators of lake levels and surface temperature over Canada, furthermore, demonstrate the extreme sensitivity of climate predictions for this geographical region to changes in the manner in which land surface processes are represented."
"7202034781;","Peru",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033664609&partnerID=40&md5=4d45c1b3eff3e2a6d53734cfba7dd3a8","The coast of Peru extends in a fairly straight line for over 3080 km. Most of the coastal zone is arid semi-desert, though the northern end has landscapes with streams and great expanses of vegetation, having notable stands of mangroves with a rich diversity. The continental shelf is up to 65 miles in the central section, but is much narrower in the southern and northern ends of the coast. Climate is influenced by the Peruvian or Humboldt Current whose cool temperature condenses moisture in the equatorial air masses, producing fog and clouds in the central coastal region. The upwelling off the Peruvian coast is exceptionally important, with marked effects on sea level, climate and on productivity. During El Nino events, the upwelling is suppressed, and the pelagic ecosystem suffers radical changes: warm waters which are poor in nutrients flow in and inhibit high primary production, and modify the composition of the plankton. The herbivorous pelagic fish which feed on the plankton are reduced as a 'tropicalization' occurs due to the migration of different species from equatorial waters. Copepods which are the dominant group during normal years and which are herbivorous, decline and are replaced by warm-water species which generally are carnivorous predators of eggs and fish larvae. Peak production of anchovy and sardine have been over 9 million tons, especially related to the first fishery resource. There has been a marked population growth since the 1950s. Habitats in the coastal zone in Peru have suffered alterations from both natural processes and various activities resulting from the increase in population and increasing demand for land. Heavy use of pesticides has produced toxic residues, although the main pollution is based on domestic and industrial residual wastes that contaminate beds of rivers, altering the quality of fresh waters and the Peruvian marine coast, but new laws and several protected areas are now encouraging environmental considerations in new development."
"55884094500;7004854638;6506495892;","ESA/RAL ATSR workshop summary",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034063219&partnerID=40&md5=7f145c640aab9a702594a481a429fd58","ESA and RAL held a joint International ATSR workshop at ESRIN, Frascati, Italy from 23 to 25 June 1999. The workshop was considered by all participants, as well as by RAL and ESA, to be a very successful meeting, and an important step in increasing the flow of information and contact among ATSR users, ESA and the ATSR project team. The purpose of this workshop was to take stock of the achievements in science and application projects using ATSR data, to introduce new applications, to discuss plans for ENVISAT, and to inform the user community of the status of the ATSR programme. A total of 36 talks, and 15 posters and demonstrations were presented to some 120 participants in five areas: CAL/VAL and AATSR, Land Applications, Clouds and Aerosol Applications, SST/Climate Monitoring and Oceanography. A CD-ROM of the proceedings will be available on request from ERS Help Desk (eohelp.esrin.esa.it) later in the year."
"7006705919;7102913661;7005513582;55207447000;6701743200;","A description of the global sulfur cycle and its controlling processes in the National Center for Atmospheric Research Community Climate Model, Version 3",2000,"10.1029/1999JD900777","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033788039&doi=10.1029%2f1999JD900777&partnerID=40&md5=321ca976c8cc3207d5b697d5a896f68c","We examine the balance between processes that contribute to the global and regional distributions of sulfate aerosol in the Earth's atmosphere using a set of simulations from the National Center for Atmospheric Research Community Climate Model, Version 3. The analysis suggests that the seasonal cycle of SO2 and SO42- are controlled by a complex interplay between transport, chemistry and deposition processes. The seasonal cycle of these species is not strongly controlled by temporal variations in emissions but by seasonal variations in volume of air processed by clouds, mass of liquid water serving as a site for aqueous chemistry, amount of oxidant available for the conversion from SO2 to SO42-, vertical transport processes, and deposition. A tagging of the sulfate by emission region (Europe, North America, Asia, and rest of world [ROW]), chemical pathway (gaseous versus in-cloud), and type of emissions (anthropogenic versus biogenic) is used to differentiate the balance of processes controlling the production and loading from this material. Significant differences exist in the destiny of SO2 molecules emitted from the several regions. An SO2 molecule emitted from the ROW source region has a much greater potential to form sulfate than one emitted from, for example, Europe. A greater fraction of the SO2 molecules is oxidized that originate from ROW compared with other areas, and once formed, the sulfate has a longer residence time (that is, it is not readily scavenged). The yield of sulfate from ROW sources of SO2 is a factor of 4 higher than that of Europe. A substantially higher fraction of the SO2 emitted over Europe is oxidized to sulfate through the ozone pathway compared to other regions. The analysis suggests that there are significant differences in the vertical distribution, and horizontal extent, of the propagation of sulfate emitted from the several source regions. Sulfate from Asian source regions reaches the farthest from its point of origin and makes a significant contribution to burdens in both hemispheres, primarily from plumes reaching out in the upper troposphere. Sulfate from other source regions tends to remain trapped in their hemisphere of origin. Copyright 2000 by the American Geophysical Union."
"6601977242;7202706097;","Ocean radiant heating. Part II: Parameterizing solar radiation transmission through the upper ocean",2000,"10.1175/1520-0485(2000)030<1849:ORHPIP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033805484&doi=10.1175%2f1520-0485%282000%29030%3c1849%3aORHPIP%3e2.0.CO%3b2&partnerID=40&md5=5db0f3bbd4182f6f2778de1501067b7e","Accurate determination of sea surface temperature (SST) is critical to the success of coupled ocean-atmosphere models and the understanding of global climate. To accurately predict SST, both the quantity of solar radiation incident at the sea surface and its divergence, or transmission, within the water column must be known. Net irradiance profiles modeled with a radiative transfer model are used to develop an empirical solar transmission parameterization that depends on upper ocean chlorophyll concentration, cloud amount, and solar zenith angle. These factors explain nearly all of the variations in solar transmission. The parameterization is developed by expressing each of the modeled irradiance profiles as a sum of four exponential terms. The fit parameters are then written as linear combinations of chlorophyll concentration and cloud amount under cloudy skies, and chlorophyll concentration and solar zenith angle during clear-sky periods. Model validation gives a climatological rms error profile that is less than 4 W m-2 throughout the water column (when normalized to a surface irradiance of 200 W m-2). Compared with existing solar transmission parameterizations this is a significant improvement in model skill. the two-equation solar transmission parameterization is incorporated into the TOGA COARE bulk flux model to quantify its effects on SST and subsequent rates of air-sea heat exchange during a low wind, high insolation period. The improved solar transmission parameterization gives a mean 12 W m-2 reduction in the quantity of solar radiation attenuated within the top few meters of the ocean compared with the transmission parameterization originally used. This results in instantaneous differences in SST and the net air-sea heat flux that often reach 0.2°C and 5 W m-2, respectively."
"6603643897;6701590624;7005069367;","Ultraviolet solar radiation at Valdivia, Chile (39.8°S)",2000,"10.1016/S1352-2310(00)00227-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034257241&doi=10.1016%2fS1352-2310%2800%2900227-2&partnerID=40&md5=bdf07d26c1252595a080c13648903b79","Daily and annual cycles of solar ultraviolet radiation were characterised at Valdivia, Chile (39.8°S), using data collected with a multichannel radiometer between January 1995 and March 1999. First, the instrument's measurements at 305 and 340nm were analysed. In a second step, erythemal dose rates and daily doses were calculated from the measured data and their daily and seasonal variation was evaluated. In January, hourly mean irradiance at noon reaches 7.4 and 64μWcm-2nm-1 for 305 and 340nm, respectively; corresponding values for July are 0.3 and 20μWcm-2nm-1. Erythemal daily doses vary from 300 to 6000Jm-2 between July and January. Episodes with high radiation are classified in duration and accumulated dose. A single event with very low total ozone and corresponding high UV levels is presented. Images from the Total Ozone Mapping Spectrometer (TOMS) are used to show its evolution. Variations in total ozone, measured from space, and cloud changes, inferred from observed UV-A radiation, explain 77% of the daily changes in UV-B. Copyright (C) 2000 Elsevier Science Ltd.Daily and annual cycles of solar ultraviolet radiation were characterized at Valdivia, Chile (39.8°S), using data collected with a multichannel radiometer between January 1995 and March 1999. First, the instrument's measurements at 305 and 340 nm were analyzed. In a second step, erythemal dose rates and daily doses were calculated from the measured data and their daily and seasonal variation was evaluated. In January, hourly mean irradiance at noon reaches 7.4 and 64 μW cm-2 nm-1 for 305 and 340 nm, respectively; corresponding values for July are 0.3 and 20 μW cm-2 nm-1. Erythemal daily doses vary from 300 to 6000 J m-2 between July and January. Episodes with high radiation are classified in duration and accumulated dose. A single event with very low total ozone and corresponding high UV levels is presented. Images from the Total Ozone Mapping Spectrometer (TOMS) are used to show its evolution. Variations in total ozone, measured from space, and cloud changes, inferred from observed UV-A radiation, explain 77% of the daily changes in UV-B."
"36127012800;7005449794;","Biosphere-atmosphere interactions over West Africa. I: Development and validation of a coupled dynamic model",2000,"10.1256/smsqj.56502","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034042998&doi=10.1256%2fsmsqj.56502&partnerID=40&md5=35c52b083413dd99bf79358af5bfd8f5","In this study we develop a zonally symmetric, synchronously coupled biosphere-atmosphere model including ecosystem dynamics, and apply this model to study biosphere-atmosphere interactions in the region of West Africa. The atmospheric model is zonally symmetric, and includes representation of atmospheric dynamics, a radiation scheme, a moist convection scheme, a boundary-layer scheme, and a cloud-parametrization scheme. The biospheric model is the Integrated BIosphere Simulator (IBIS), which includes representation of the water, energy, momentum, and carbon balance, vegetation phenology, and vegetation dynamics. We modified the representation of canopy hydrology in IBIS to account for the impact of rainfall subgrid variability. The biospheric model and atmospheric model are separately tested against observations. The synchronously coupled model is then used to simulate the biosphere-atmosphere system of West Africa. A study on the role of biosphere-atmosphere interactions, including ecosystem dynamics, in the climate variability over West Africa using this model will be presented in a companion paper."
"7102866124;","The Amazon energy budget using the ABLE-2B and FluAmazon data",2000,"10.1175/1520-0469(2000)057<3131:TAEBUT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034276856&doi=10.1175%2f1520-0469%282000%29057%3c3131%3aTAEBUT%3e2.0.CO%3b2&partnerID=40&md5=248514a43196bb58c6d0f3e402b04982","Radiosonde and satellite data collected from the Atmosphere Boundary Layer Experiment-Wet Season and Amazon Water Vapor Flux Experiment are used to investigate the energy budget. The relationship between the cloud cover variability and the different terms of the energy budget equations was examined. The radiosonde data were used to compute the energy divergence flux for each triangle composed by three radiosonde stations. Earth Radiation Budget Experiment data were used to compute the radiative flux in the top of the atmosphere. The cloud cover variability were computed from the International Satellite Cloud Climatology Project data. When the atmosphere undergoes a change from the mean state to the convective state, it stores energy mainly in the middle layers, while the maximum energy storage was found around 650 hPa mainly due to the perturbation of the latent energy. Conversely, when the atmosphere undergoes a change from a mean state to a nearly clear sky situation, the atmosphere column loses energy, principally due to the changes in the latent energy profile, and the atmosphere became drier, in the 700-200-hPa layer. The advective term of the energy divergence flux is of a lower order and the energy divergence flux is determined mainly from the divergent term. The profiles of the components of the energy divergence flux are essentially a result of the wind divergence weighted by the specific humidity (latent term), temperature (enthalpy term), and height (potential term). The latent energy divergence flux, for convective situations, presents a maximum in 950 hPa and is always negative (convergent) up to 400 hPa. For the nearly clear-sky situation a convergence of humidity in the lower levels and an important humidity divergence above 800 hPa were observed. The enthalpy and the latent energy divergence flux mainly describe the middle/low levels and the potential energy divergence flux represents mainly the upper troposphere. During the experiments, the solar energy absorbed by the surface was always smaller than the total surface flux supplied to the atmosphere during convective events and always larger than the total surface flux supplied to the atmosphere during nonconvective events. This means that the surface loses more energy than it receives in convective events and vice versa. The quantity of energy stored at the surface seems to be limited, defining a timescale, during which the surface needs to export or receive energy to control its deficit or gain of energy.Radiosonde and satellite data collected from the Atmosphere Boundary Layer Experiment-Wet Season and Amazon Water Vapor Flux Experiment are used to investigate the energy budget. The relationship between the cloud cover variability and the different terms of the energy budget equations was examined. The radiosonde data were used to compute the energy divergence flux for each triangle composed by three radiosonde stations. Earth Radiation Budget Experiment data were used to compute the radiative flux in the top of the atmosphere. The cloud cover variability were computed from the International Satellite Cloud Climatology Project data. When the atmosphere undergoes a change from the mean state to the convective state, it stores energy mainly in the middle layers, while the maximum energy storage was found around 650 hPa mainly due to the perturbation of the latent energy. Conversely, when the atmosphere undergoes a change from a mean state to a nearly clear sky situation, the atmosphere column loses energy, principally due to the changes in the latent energy profile, and the atmosphere became drier, in the 700-200-hPa layer. The advective term of the energy divergence flux is of a lower order and the energy divergence flux is determined mainly from the divergent term. The profiles of the components of the energy divergence flux are essentially a result of the wind divergence weighted by the specific humidity (latent term), temperature (enthalpy term), and height (potential term). The latent energy divergence flux, for convective situations, presents a maximum in 950 hPa and is always negative (convergent) up to 400 hPa. For the nearly clear-sky situation a convergence of humidity in the lower levels and an important humidity divergence above 800 hPa were observed. The enthalpy and the latent energy divergence flux mainly describe the middle/low levels and the potential energy divergence flux represents mainly the upper troposphere. During the experiments, the solar energy absorbed by the surface was always smaller than the total surface flux supplied to the atmosphere during convective events and always larger than the total surface flux supplied to the atmosphere during nonconvective events. This means that the surface loses more energy than it receives in convective events and vice versa. The quantity of energy stored at the surface seems to be limited, defining a timescale, during which the surface needs to export or receive energy to control its deficit or gain of energy."
"57206505383;36941730100;7202129754;7102425008;","Dynamical effects of ice sublimation in a frontal wave",2000,"10.1002/qj.49712656804","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033816141&doi=10.1002%2fqj.49712656804&partnerID=40&md5=863cb9faafaf7eba8990afbc8837f7c7","The dynamical role of ice sublimation in weather systems is briefly reviewed. Observations are presented from the Fronts and Atlantic Storm-Track EXperiment (FASTEX) Intensive Observation Period 16 that show variations of static stability, humidity and mesoscale circulation corresponding to those associated theoretically with sublimation of ice precipitation. It is thus suggested that the observations display the mechanism proposed by Clough and Franks in which forward mesoscale flows are associated with moist adiabatic descent supported by the sublimation cooling. This mechanism was suggested as an important stage in the evolution of many mesoscale rain bands. A set of three model simulations of the event has been made with versions of The Met. Office's Unified Model. Of these a mesoscale model integration with 11 km resolution and 45 levels clearly displays the symptoms, and is diagnosed to demonstrate its consistency with the Clough-Franks mechanism. An integration omitting the cooling due to sublimation differs significantly from the full model experiment in the structure of low-level wind fields, frontal troughs and mesoscale precipitation distribution. It is also demonstrated that the static-stability transition, mesoscale circulation and mid-tropospheric potential-vorticity perturbations are substantially weakened in this integration, thus confirming that the Clough-Franks mechanism is also operating in the numerical weather prediction (NWP) model. We deduce from these studies that ice precipitation and its sublimation has a major role in determining mesoscale circulation and structure in mid-latitude weather systems, affecting stratification and the formation of features such as fronts and rain bands. These are substantially affected by the fall and evaporation of ice crystals, which are both important to temperature and moisture transports and the behaviour of NWP models on timescales of hours to days. In our integrations dynamical feedback due to sublimation cooling coincided with extreme negative potential-vorticity values and potentially conditional symmetric instability, hence the anticyclonic motion occurring in the cloud head or deep cloud of the moist warm sector as in this case. In moist warm sectors a substantial role for sublimation may be anticipated more generally, particularly for air trajectories receiving most ice precipitation. We suggest that the described phenomenon be referred to as sublimation enhanced descent or SED. It is concluded that in view of this demonstrated sensitivity substantial attention should be given to refining microphysical parametrizations in NWP models, and that radar and sounding observations from the FASTEX experiment provide a suitable basis for validating these schemes."
"7003531755;7004613089;7004927007;7006558339;57199409202;6602423682;6604085240;","Causes of Atlantic Ocean climate variability between 1958 and 1998",2000,"10.1175/1520-0442(2000)013<2845:COAOCV>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253139&doi=10.1175%2f1520-0442%282000%29013%3c2845%3aCOAOCV%3e2.0.CO%3b2&partnerID=40&md5=4eacf0498e52f486680361f343e5d14b","Numerical experiments are performed to examine the causes of variability of Atlantic Ocean SST during the period covered by the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis (1958-98). Three ocean models are used. Two are mixed layer models: one with a 75-m-deep mixed layer and the other with a variable depth mixed layer. For both mixed layer models the ocean heat transports are assumed to remain at their diagnosed climatological values. The third model is a full dynamical ocean general circulation model (GCM). All models are coupled to a model of the subcloud atmospheric mixed layer (AML). The AML model computes the air temperature and humidity by balancing surface fluxes, radiative cooling, entrainment at cloud base, advection and eddy heat, and moisture transports. The models are forced with NCEP-NCAR monthly mean winds from 1958 to 1998. The ocean mixed layer models adequately reproduce the dominant pattern of Atlantic Ocean climate variability in both its spatial pattern and time dependence. This pattern is the familiar tripole of alternating zonal bands of SST anomalies stretching between the subpolar gyre and the subtropics. This SST pattern goes along with a wind pattern that corresponds to the North Atlantic Oscillation (NAO). Analysis of the results reveals that changes in wind speed create the subtropical SST anomalies while at higher latitudes changes in advection of temperature and humidity and changes in atmospheric eddy fluxes are important. An observational analysis of the boundary layer energy balance is also performed. Anomalous atmospheric eddy heat fluxes are very closely tied to the SST anomalies. Anomalous horizontal eddy fluxes damp the SST anomalies while anomalous vertical eddy fluxes tend to cool the entire midlatitude North Atlantic during the NAO's high-index phase with the maximum cooling exactly where the SST gradient is strengthened the most. The SSTs simulated by the ocean mixed layer model are compared with those simulated by the dynamic ocean GCM. In the far North Atlantic Ocean anomalous ocean heat transports are equally important as surface fluxes in generating SST anomalies and they act constructively. The anomalous heat transports are associated with anomalous Ekman drifts and are consequently in phase with the changing surface fluxes. Elsewhere changes in surface fluxes dominate over changes in ocean heat transport. These results suggest that almost all of the variability of the North Atlantic SST in the last four decades can be explained as a response to changes in surface fluxes caused by changes in the atmospheric circulation. Changes in the mean atmospheric circulation force the SST while atmospheric eddy fluxes dampen the SST. Both the interannual variability and the longer timescale changes can be explained in this way. While the authors were unable to find evidence for changes in ocean heat transport systematically leading or lagging development of SST anomalies, this leaves open the problem of explaining the causes of the low-frequency variability. Possible causes are discussed with reference to the modeling results.Numerical experiments are performed to examine the causes of variability of Atlantic Ocean SST during the period covered by the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis (1958-98). Three ocean models are used. Two are mixed layer models: one with a 75-m-deep mixed layer and the other with a variable depth mixed layer. For both mixed layer models the ocean heat transports are assumed to remain at their diagnosed climatological values. The third model is a full dynamical ocean general circulation model (GCM). All models are coupled to a model of the subcloud atmospheric mixed layer (AML). The AML model computes the air temperature and humidity by balancing surface fluxes, radiative cooling, entrainment at cloud base, advection and eddy heat, and moisture transports. The models are forced with NCEP-NCAR monthly mean winds from 1958 to 1998. The ocean mixed layer models adequately reproduce the dominant pattern of Atlantic Ocean climate variability in both its spatial pattern and time dependence. This pattern is the familiar tripole of alternating zonal bands of SST anomalies stretching between the subpolar gyre and the subtropics. This SST pattern goes along with a wind pattern that corresponds to the North Atlantic Oscillation (NAO). Analysis of the results reveals that changes in wind speed create the subtropical SST anomalies while at higher latitudes changes in advection of temperature and humidity and changes in atmospheric eddy fluxes are important. An observational analysis of the boundary layer energy balance is also performed."
"6603809220;7101945366;7102604282;","Precipitation changes in a GCM resulting from the indirect effects of anthropogenic aerosols",2000,"10.1029/2000GL011737","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033625902&doi=10.1029%2f2000GL011737&partnerID=40&md5=94054faee1e1e670b87d80a6a353c390","An atmospheric GCM coupled to a mixed-layer ocean model is used to study changes in rainfall due to the indirect effects of anthropogenic aerosols. The model includes treatments of both the first and second indirect effects. The most striking feature of the equilibrium rainfall response to the indirect effects of anthropogenic aerosols is a southward shift of the equatorial rainfall. We hypothesize that this is caused by a hemispheric asymmetry in the cooling of the sea surface. This is supported by another pair of experiments, in which the model is run with prescribed present-day SSTs. In one experiment the standard model is used, and in the other the SSTs in the Northern Hemisphere are increased by 1 K in the calculation of the surface fluxes, to mimic the effect of a return to pre-industrial conditions. Compared to the run with increased NH SST, the standard run shows a southward shift of equatorial rainfall, similar to that obtained as a response to anthropogenic aerosols."
"6603821988;7402093416;7401751388;6603887794;6506060158;","The response of the stratospheric climate to projected changes in the concentrations of well-mixed greenhouse gases from 1992 to 2051",2000,"10.1175/1520-0442(2000)013<2142:TROTSC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034233151&doi=10.1175%2f1520-0442%282000%29013%3c2142%3aTROTSC%3e2.0.CO%3b2&partnerID=40&md5=a90509f821cce25e137f6f2612d7f924","Results are presented from two 60-yr integrations of the troposphere-stratosphere configuration of the U.K. Met. Office's Unified Model. The integrations were set up identically, apart from different initial conditions, which, nonetheless, were both representative of the early 1990s. Radiative heating rates were calculated using the IS92A projected concentrations of the well-mixed greenhouse gases (GHGs) given by the Intergovernmental Panel on Climate Change, but changes in stratospheric ozone and water vapor were not included. Sea surface conditions were taken from a separate coupled ocean-atmosphere experiment. Both integrations reproduced the familiar pattern of tropospheric warming and a stratospheric cooling increasing with height to about -1.4 K per decade at 1 mb. There was good agreement in the trends apart from in the polar upper stratosphere and, to a greater extent, the polar lower-to-middle stratosphere, where there is significant interannual variability during the winter months. Even after decadal smoothing, the trends in the northern winter were still overshadowed by the variability resulting from the planetary wave forcing from the troposphere. In general, the decadal variability of the Northern Hemisphere stratosphere was not a manifestation of a uniform change throughout each winter but, as with other models, there was a change in the frequency of occurrence of sudden stratospheric warmings. Unlike previous studies, the different results from the two simulations confirm the change in frequency of warmings was due to internal atmospheric variability and not the prescribed changes in GHG concentrations or sea surface conditions. In the southern winter stratosphere the flux of wave activity from the troposphere increased, but any additional dynamical heating was more than offset by the extra radiative cooling from the growing total GHG concentration. Consequently the polar vortex became more stable, with the spring breakdown delayed by 1-2 weeks by the 2050s. Polar stratospheric cloud (PSC) amounts inferred from the predicted temperatures increased in both hemispheres, especially in the early winter. In the Southern Hemisphere, the region of PSC formation expanded both upward and equatorward in response to the temperature trend.Results are presented from two 60-yr integrations of the troposphere-stratosphere configuration of the U.K. Met. Office's Unified Model. The integrations were set up identically, apart from different initial conditions, which, nonetheless, were both representative of the early 1990s. Radiative heating rates were calculated using the IS92A projected concentrations of the well-mixed greenhouse gases (GHGs) given by the Intergovernmental Panel on Climate Change, but changes in stratospheric ozone and water vapor were not included. Sea surface conditions were taken from a separate coupled ocean-atmosphere experiment. Both integrations reproduced the familiar pattern of tropospheric warming and a stratospheric cooling increasing with height to about -1.4 K per decade at 1 mb. There was good agreement in the trends apart from in the polar upper stratosphere and, to a greater extent, the polar lower-to-middle stratosphere, where there is significant interannual variability during the winter months. Even after decadal smoothing, the trends in the northern winter were still overshadowed by the variability resulting from the planetary wave forcing from the troposphere. In general, the decadal variability of the Northern Hemisphere stratosphere was not a manifestation of a uniform change throughout each winter but, as with other models, there was a change in the frequency of occurrence of sudden stratospheric warmings. Unlike previous studies, the different results from the two simulations confirm the change in frequency of warmings was due to internal atmospheric variability and not the prescribed changes in GHG concentrations or sea surface conditions. In the southern winter stratosphere the flux of wave activity from the troposphere increased, but any additional dynamical heating was more than offset by the extra radiative cooling from the growing total GHG concentration. Consequently the polar vortex became more stable, with the spring breakdown delayed by 1-2 weeks by the 2050s. Polar stratospheric cloud (PSC) amounts inferred from the predicted temperatures increased in both hemispheres, especially in the early winter. In the Southern Hemisphere, the region of PSC formation expanded both upward and equatorward in response to the temperature trend."
"6603829269;7006667679;7006646563;7005650796;6603312650;7003602405;","Aerosol optical depth for atmospheric correction of AVHRR composite data",2000,"10.1080/07038992.2000.10874778","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034239837&doi=10.1080%2f07038992.2000.10874778&partnerID=40&md5=8f09c7981381ee89a498e3287cdddf9b","The Canada Centre for Remote Sensing (CCRS) Geocoding and Compositing system (GeoComp-n) processes the Advanced Very High Resolution Radiometer (AVHRR) data from the United States National Oceanic and Atmospheric Administration (NOAA) series of satellites. The GeoComp-n system produces single- or multi-date composite maps of surface reflectance of the Canada landmass in the AVHRR visible and near-infrared spectral bands at a spatial resolution of 1 km. The data must first be processed into accurate geophysical units in order to utilize these maps and their derived products for various global climate and land cover change studies. In the case of satellite data, this not only implies the accurate radiometric calibration but also the proper atmospheric correction of image data. One of the key parameters required for atmospheric correction is the aerosol optical depth. The Canadian sunphotometer network, AEROCAN, provides spatially sparse but near real-time (seasonal) aerosol optical depth coverage across Canada. One of the goals of AEROCAN is to develop an aerosol climatology that can be used for operational atmospheric correction of satellite data. This research note reviews the current holdings in the AEROCAN aerosol database after cloud screening. The data tables and seasonal profiles presented support the conclusion at this time that a single, Canada-wide, time-invariant optical depth is acceptable for the first-order operational atmospheric correction of AVHRR composite image data. The best estimate of this aerosol optical depth at a wavelength of 500 nm (AOD500) is 0.07, with an uncertainty of +0.070/-0.035, as generated from the AEROCAN database. This corresponds to an aerosol optical depth at a wavelength of 550 nm (AOD550) of atmospheric correction code in GeoComp-n. A sensitivity study demonstrates that this uncertainty in AOD500 produces an absolute error in surface reflectance of ±1% for the worst case of a black spruce forest, which is acceptable for GeoComp-n with an absolute accuracy requirement of ±5%."
"6505776326;55335220500;6602325588;","Recent trends of minimum and maximum surface temperatures over Eastern Africa",2000,"10.1175/1520-0442(2000)013<2876:RTOMAM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253131&doi=10.1175%2f1520-0442%282000%29013%3c2876%3aRTOMAM%3e2.0.CO%3b2&partnerID=40&md5=9f3db84dffcfd68b502beee0f3a7c79d","This study investigated recent trends in the mean surface minimum and maximum air temperature over eastern Africa by use of both graphical and statistical techniques. Daily records for 71 stations for the period 1939-92 were used. Attempts were also made to associate the temperature characteristics with the anomalies in the major systems that control the climate of the region including the El Nino-Southern Oscillation (ENSO), the quasi-biennial oscillation, and the prevailing convective processes represented by the outgoing longwave radiation. The northern part of the study region generally indicated nighttime warming and daytime cooling in recent years. The trend patterns were, however, reversed at coastal and lake areas. The Mozambique channel region showed cooling during both nighttime and daytime. There were thus large geographical and temporal variations in the observed trends, with some neighboring locations at times indicating opposite trends. A significant feature in the temperature variability patterns was the recurrence of extreme values. Such recurrences were significantly correlated with the patterns of convective activities, especially ENSO, cloudiness, and above/below normal rainfall. Although some of the variations in the trend patterns could be attributed to urbanization and land use patterns, such effects were not delineated in the current study.This study investigated recent trends in the mean surface minimum and maximum air temperatures over eastern Africa by use of both graphical and statistical techniques. Daily records for 71 stations for the period 1939-92 were used. Attempts were also made to associate the temperature characteristics with the anomalies in the major systems that control the climate of the region including the El Nino-Southern Oscillation (ENSO), the quasi-biennial oscillation, and the prevailing convective processes represented by the outgoing longwave radiation. The northern part of the study region generally indicated nighttime warming and daytime cooling in recent years. The trend patterns were, however, reversed at coastal and lake areas. The Mozambique channel region showed cooling during both nighttime and daytime. There were thus large geographical and temporal variations in the observed trends, with some neighboring locations at times indicating opposite trends. A significant feature in the temperature variability patterns was the recurrence of extreme values. Such recurrences were significantly correlated with the patterns of convective activities, especially ENSO, cloudiness, and above/below normal rainfall. Although some of the variations in the trend patterns could be attributed to urbanization and land use patterns, such effects were not delineated in the current study."
"6602199449;6508019200;","The urban heat island in a small city in coastal Portugal",2000,"10.1007/s004840000063","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034320273&doi=10.1007%2fs004840000063&partnerID=40&md5=a66745b54c9abb183ed4c9d8a5168998","This project arose from the need to study the phenomenon of the urban heat island, since only by recognising this phenomenon can we moderate it to improve the human and urban environments. Not only big cities develop urban heat islands. This study detected the presence and recorded the characteristics of an urban heat island in the small coastal city of Aveiro, Portugal. The study was developed through the scheduled measurements of air temperature and the analysis of the geographical, meteorological and urban conditions. The form and intensity of Aveiro's heat island are a response to the interaction of three principal factors: the urban morphology (the hottest zones in the city are those with the tallest and the highest density of buildings, without green spaces and with intense generation of heat from traffic, commerce and services); the meteorological conditions (the intensity of the island is at its maximum when the sky is totally clear and there is no wind, and at its minimum in those situations when there is atmospheric instability, such as wind, cloud and precipitation); and the proximity of the coastal lagoon (which borders the city to the west and northwest and moderates seasonal temperatures. The urban heat island influences the comfort and health of its inhabitants, thus urban planning is very important in the moderation and prevention of this phenomenon."
"7501757094;57198472289;55462121400;","A regional model simulation of the 1991 severe precipitation event over the Yangtze-Huai River valley. Part I: Precipitation and circulation statistics",2000,"10.1175/1520-0442(2000)013<0074:ARMSOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034030643&doi=10.1175%2f1520-0442%282000%29013%3c0074%3aARMSOT%3e2.0.CO%3b2&partnerID=40&md5=fa5e1a07b94da8c44e4bb2fb8779e465","The summer Mei-yu event over eastern China, which is strongly influenced by large-scale circulation, is an important aspect of East Asian climate; for example, the Mei-yu frequently brings heavy precipitation to the Yangtze-Huai River valley (YHRV). Both observations and a regional model were used to study the Mei-yu front and its relation to large-scale circulation during the summer of 1991 when severe floods occurred over YHRV. This study has two parts: the first part, presented here, analyzes the association between heavy Mei-yu precipitation and relevant large-scale circulation, while the second part, documented by W. Gong and W.-C. Wang, examines the model biases associated with the treatment of lateral boundary conditions (the objective analyses and coupling schemes) used as the driving fields for the regional model. Observations indicate that the Mei-yu season in 1991 spans 18 May-14 July, making it the longest Mei-yu period during the last 40 yr. The heavy precipitation over YHRV is found to be intimately related to the western Pacific subtropical high, upper-tropospheric westerly jet at midlatitudes, and lower-tropospheric southwest wind and moisture flux. The regional model simulates reasonably well the regional mean surface air temperature and precipitation, in particular the precipitation evolution and its association with the large-scale circulation throughout the Mei-yu season. However, the model simulates smaller precipitation intensity, which is due partly to the colder and drier model atmosphere resulting from excessive low-level clouds and the simplified land surface process scheme used in the present study.The summer Mei-yu event over eastern China, which is strongly influenced by large-scale circulation, is an important aspect of East Asian climate; for example, the Mei-yu frequently brings heavy precipitation to the Yangtze-Huai River valley (YHRV). Both observations and a regional model were used to study the Mei-yu front and its relation to large-scale circulation during the summer of 1991 when severe floods occurred over YHRV. This study has two parts: the first part, presented here, analyzes the association between heavy Mei-yu precipitation and relevant large-scale circulation, while the second part, documented by W. Gong and W.-C. Wang, examines the model biases associated with the treatment of lateral boundary conditions (the objective analyses and coupling schemes) used as the driving fields for the regional model. Observations indicate that the Mei-yu season in 1991 spans 18 May-14 July, making it the longest Mei-yu period during the last 40 yr. The heavy precipitation over YHRV is found to be intimately related to the western Pacific subtropical high, upper-tropospheric westerly jet at midlatitudes, and lower-tropospheric southwest wind and moisture flux. The regional model simulates reasonably well the regional mean surface air temperature and precipitation, in particular the precipitation evolution and its association with the large-scale circulation throughout the Mei-yu season. However, the model simulates smaller precipitation intensity, which is due partly to the colder and drier model atmosphere resulting from excessive low-level clouds and the simplified land surface process scheme used in the present study."
"6603737407;7103175592;55987234400;35549146800;6603585313;6603557510;","World Wide Web Access to Radiation Datasets for Environmental and Climate Change Studies",2000,"10.1175/1520-0477(2000)081<2645:WWWATR>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042686749&doi=10.1175%2f1520-0477%282000%29081%3c2645%3aWWWATR%3e2.3.CO%3b2&partnerID=40&md5=8b9397020e53728114ae2ec7b3f8d74f","Five years of scanner data from the Earth Radiation Budget Experiment (ERBE), eight years of surface radiation budget (SRB) data, and one year of scanner radiation budget data from the French-Russian-German experiment, ScaRaB, will be available for use by colleges and universities [and primary and secondary (K-12) schools] over a World Wide Web browser. The database for ERBE is a 5-yr monthly average time series from February 1985 through December 1989, and ScaRaB is a 1-yr dataset from February 1994 to March 1995. ERBE and ScaRaB include shortwave radiative fluxes, emitted longwave radiative fluxes, and the earth's albedo measured at the top of the atmosphere. The SRB dataset spans the period from July 1983 through June 1991 and includes surface downward shortwave fluxes, surface downward longwave fluxes, surface albedos, and cloud percent. Students will have access to the data in three ways. They can display general image format images of any month and visually observe month-to-month or interannual variations. The data files for each month also have a spreadsheet format and can be downloaded in their entirety into any spreadsheet application program for further analysis. Third, using a live access server (LAS), students can interact directly with the data to select and subset datasets in terms of month, year, latitude, and longitude. The LAS allows students to view images of subsetted regions, and to subset data values to a file for further analysis. The server for this dataset is located at the National Aeronautics and Space Administration Langley Research Center, Hampton, Virginia."
"54790508000;7102650724;7006287459;","Estimating mean monthly incident solar radiation on horizontal and inclined slopes from mean monthly temperatures extremes",2000,"10.1007/s004840000073","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034323930&doi=10.1007%2fs004840000073&partnerID=40&md5=e9f1b15ccf83205187e4ed06f9b6059d","Although satellite-borne sensors are now available to estimate cloud cover and incoming short-wave radiation across the Earth's surface, the study of climatic variation and its impact on terrestrial and marine ecosystems involves historical analyses of data from networks of weather stations that only record extremes in temperatures and precipitation on a daily basis. Similarly, when projections are made with global atmospheric circulation models, the spatial resolution of predicted radiation is too coarse to incorporate the effects of heterogeneous topography. In this paper, we review the development and set forth a set of general equations that allow both diffuse and direct solar radiation to be estimated for each month on the basis of mean daily maximum and minimum temperatures, latitude, elevation, slope, and aspect. Adjustments for differences in slope, aspect, and elevation are made by varying the fraction of diffuse and direct solar beam radiation. To test the equations on various slopes and under different climatic conditions, we drew on high-quality radiation data recorded at a number of sites on three continents. On horizontal surfaces the set of equations predicted both direct and diffuse components of solar radiation within 1%-7% of recorded values. On slopes, estimates of monthly mean solar radiation were with 13% of observed values with a mean error of less than 2 MJ m-2day-1 over any given month."
"6602192784;","Sun avoidance in the yellow baboons (Papio cynocephalus cynocephalus) of Ruaha National Park, Tanzania. Variations with season, behavior and weather",2000,"10.1007/s004840000058","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034267212&doi=10.1007%2fs004840000058&partnerID=40&md5=61e3853a3eedeedd105df40e1021790b","Do free-ranging baboons avoid traveling towards the sun? Sun avoidance, in addition to resource and predator locations, may influence troop movement and non-random use of the home range. This paper investigates how sun avoidance, as measured by facial exposure to sunlight, influences directional choices. It hypothesizes that baboons should avoid the sun in the hot, dry season and show indifference to it in the cool, lush season. This paper also hypothesizes that baboons employ sun-avoidance behaviors more while they forage or travel to resting sites than when they travel to foraging sites or engage in active social behaviors; lastly this paper hypothesizes that sun altitude, temperature, humidity, and cloud cover influence sun-avoidance behavior. Using focal-animal techniques on 21 males from free-ranging baboon troops, I collected locational data, accurate to within 1.6 m, over 15 months. I calculated the difference between baboon bearings and the sun's azimuth in angular degrees. Both linear and circular statistics indicate that baboons put significantly (P<0.01) more than 90° between their bearing and the sun's azimuth under certain conditions. Contrary to hypotheses based on the detrimental effects of insolation, baboons in the cool, lush season avoid the sun, while baboons in the hot, dry season do not. In the lush season, the extent to which baboons avoid the sun does not depend on their other behaviors. Dry-season baboons demonstrate stronger sun avoidance while resting than when engaged in other behaviors. Finally, in the dry season, temperature drives sun avoidance; humidity drives it in the lush season."
"7403288995;7102875645;","Suppression of ENSO in a coupled model without water vapor feedback",2000,"10.1007/s003820050336","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034112974&doi=10.1007%2fs003820050336&partnerID=40&md5=adafafec0367a9ada7694f69ff5d834f","We examine 800-year time series of internally generated variability in both a coupled ocean-atmosphere model where water vapor anomalies are not allowed to interact with longwave radiation and one where they are. The ENSO-like phenomenon in the experiment without water vapor feedback is drastically suppressed both in amplitude and geographic extent relative to the experiment with water vapor feedback. Surprisingly, the reduced amplitude of ENSO-related sea surface temperature anomalies in the model without water vapor feedback cannot be attributed to greater longwave damping of sea surface temperature. (Differences between the two experiments in radiative feedback due to clouds counterbalance almost perfectly the differences in radiative feedback due to water vapor.) Rather, the interaction between water vapor anomalies and longwave radiation affects the ENSO-like phenomenon through its influence on the vertical structure of radiative heating: Because of the changes in water vapor associated with it, a given warm equatorial Pacific sea surface temperature anomaly is associated with a radiative heating profile that is much more gravitationally unstable when water vapor feedback is present. The warm sea surface temperature anomaly therefore results in more convection in the experiment with water vapor feedback. The increased convection, in turn, is related to a larger westerly wind-stress anomaly, which creates a larger decrease in upwelling of cold water, thereby enhancing the magnitude of the original warm sea surface temperature anomaly. In this manner, the interaction between water vapor anomalies and longwave radiation magnifies the air-sea interactions at the heart of the ENSO phenomenon; without this interaction, the coupling between sea surface temperature and wind stress is effectively reduced, resulting in smaller amplitude ENSO episodes with a more limited geographical extent."
"56271066200;36490968700;7202884070;7410021427;56691869300;55473886300;57207592379;8323763900;7004933306;7005052907;","Suominet: A real-time national GPS network for atmospheric research and education",2000,"10.1175/1520-0477(2000)081<0677:SARNGN>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000055161&doi=10.1175%2f1520-0477%282000%29081%3c0677%3aSARNGN%3e2.3.CO%3b2&partnerID=40&md5=fbe12a643dfb75e0c1e860d411d63387","""SuomiNet,"" a university-based, real-time, national Global Positioning System (GPS) network, is being developed for atmospheric research and education with funding from the National Science Foundation and with cost share from collaborating universities. The network, named to honor meteorological satellite pioneer Verner Suomi, will exploit the recently shown ability of ground-based GPS receivers to make thousands of accurate upper- and lower-atmospheric measurements per day. Phase delays induced in GPS signals by the ionosphere and neutral atmosphere can be measured with high precision simultaneously along a dozen or so GPS ray paths in the field of view. These delays can be converted into integrated water vapor (if surface pressure data or estimates are available) and total electron content (TEC), along each GPS ray path. The resulting continuous, accurate, all-weather, real-time GPS moisture data will help advance university research in mesoscale modeling and data assimilation, severe weather, precipitation, cloud dynamics, regional climate, and hydrology. Similarly, continuous, accurate, all-weather, real-time TEC data have applications in modeling and prediction of severe terrestrial and space weather, detection and forecasting of low-altitude ionospheric scintillation activity and geomagnetic storm effects at ionospheric midlatitudes, and detection of ionospheric effects induced by a variety of geophysical events. SuomiNet data also have potential applications in coastal meteorology, providing ground truth for satellite radiometry, and detection of scintillation associated with atmospheric turbulence in the lower troposphere. The goal of SuomiNet is to make large amounts of spatially and temporally dense GPS-sensed atmospheric data widely available in real time, for academic research and education. Information on participation in SuomiNet is available via www.unidata.ucar.edu/suominet."
"7401559815;7409322518;7408519295;","Dynamical and boundary forcing characteristics of regional components of the Asian summer monsoon",2000,"10.1175/1520-0442(2000)013<2461:DABFCO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034233180&doi=10.1175%2f1520-0442%282000%29013%3c2461%3aDABFCO%3e2.0.CO%3b2&partnerID=40&md5=c38effbd0a6dcf478051471c0fcf2c17","In this paper, the authors present a description of the internal dynamics and boundary forcing characteristics of two major subcomponents of the Asian summer monsoon (ASM), that is, the South Asian monsoon (SAM) and the East-Southeast Asian monsoon (EAM). The description is based on a new monsoon-climate paradigm in which the variability of ASM is considered as the outcome of the interplay of a 'fast' and an 'intermediate' monsoon subsystem, under the influence of 'slow' external forcings. Two sets of regional monsoon indices derived from dynamically consistent rainfall and wind data are used in this study. Results show that the internal dynamics of SAM are representative of a 'classical' monsoon system in which the anomalous circulation is governed by Rossby wave dynamics, where anomalous vorticity induced by an off-equatorial heat source is balanced by the advection of planetary vorticity. On the other hand, the internal dynamics of EAM are characterized by a 'hybrid' monsoon system featuring multicellular meridional circulation over the East Asian sector, extending from the deep Tropics to the midlatitudes. These meridional cells link tropical heating to extratropical circulation systems via the East Asian jet stream and are responsible for the observed zonally oriented anomalous rainfall patterns over East and Southeast Asia and the subtropical western Pacific. In the extratropical regions, the major upper-level vorticity balance is between the advection and generation by anomalous divergent circulation and basic-state circulation. A consequence of the different dynamical underpinnings is that EAM is associated with stronger extratropical teleconnection patterns to regions outside ASM compared to SAM. The interannual variability of SAM is linked to basin-scale SST fluctuation with pronounced signals in the equatorial eastern Pacific. During the boreal spring, warming of the Arabian Sea and the subtropical western Pacific may lead to a strong SAM. For EAM, interannual variability is tied to SST anomalies over the East China Sea, the Sea of Japan (East Sea), and the South China Sea regions, while the linkage to equatorial basin-scale SST anomaly is weak at best. A strong EAM is foreshadowed by a large-scale SST anomaly dipole with warming (cooling) in the subtropical central (eastern) Pacific. Comparison with the P. J. Webster and S. Yang (WY) monsoon index shows that WY is not significantly correlated with either the SAM or EAM regional-scale rainfall separately. It is demonstrated that WY can be considered as a measure of the large-scale atmospheric circulation state over the Indian/Pacific Ocean basin, including the integrated heat source over the ASM region. As such, the regional monsoon indices developed in this paper and WY provide a complementary description of the broadscale and regional aspects of the ASM.A description is given of the internal dynamics and boundary forcing characteristics of two major subcomponents of the Asian summer monsoon (ASM), that is, the South Asian monsoon (SAM) and the East-Southeast Asian monsoon (EAM). The description is based on a new monsoon-climate paradigm in which the variability of ASM is considered as the outcome of the interplay of a 'fast' and an 'intermediate' monsoon subsystem."
"7401581934;7601467628;7403959083;","The use of quasi-nonhydrostatic models for mesoscale weather prediction",2000,"10.1175/1520-0469(2000)057<2493:TUOQNM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253438&doi=10.1175%2f1520-0469%282000%29057%3c2493%3aTUOQNM%3e2.0.CO%3b2&partnerID=40&md5=19dadd813749dcc9c60e947554d92a12","In recent years, there has been extensive study of the mathematical basis of weather prediction leading to a new system of continuous equations that are well posed, and a set of conditions that make discrete atmospheric and other models stable and potentially more accurate. In particular, the theory deals with initial boundary value problems that admit multiple timescales. Using this theory, a quasi-nonhydrostatic model called QNH was developed at NOAA's Forecast Systems Laboratory. The model is fully compressible and explicit in the vertical as well as the horizontal direction. It is characterized by a parameter, 'α' (typically the square of the vertical to horizontal aspect ratio), which multiplies the hydrostatic terms in the vertical equation of motion. In this paper, the authors describe the theoretical basis for the use of these models in mesoscale weather prediction. It is shown that for the mesoscale, the parameter has the effect of decreasing both the frequency and amplitude of the gravity wave perturbation response to small-scale impulses in forcing and to unbalanced initial conditions. This allows a modeler to choose a length scale below which gravity wave generation is suppressed. A weakness of the approach is that the hydrostatic adjustment process is slowed down. The analysis indicates that the parameter does not have an effect on the Rossby waves, the larger horizontal-scale gravity waves, nor on forced solutions such as those created by heating. The bounded derivative initialization is discussed. Since the speeds of the vertical acoustic waves are decreased, quasi-nonhydrostatic models can calculate the vertical equations explicitly and still meet the Courant-Friedrichs-Levy criteria. It is concluded that the unique characteristics of quasi-nonhydrostatic models may make them valuable in mesoscale weather prediction, particularly of clouds and precipitation.In recent years, there has been extensive study of the mathematical basis of weather prediction leading to a new system of continuous equations that are well posed, and a set of conditions that make discrete atmospheric and other models stable and potentially more accurate. In particular, the theory deals with initial boundary value problems that admit multiple timescales. Using this theory, a quasi-nonhydrostatic model called QNH was developed at NOAA's Forecast Systems Laboratory. The model is fully compressible and explicit in the vertical as well as the horizontal direction. It is characterized by a parameter, 'α' (typically the square of the vertical to horizontal aspect ratio), which multiplies the hydrostatic terms in the vertical equation of motion. In this paper, the authors describe the theoretical basis for the use of these models in mesoscale weather prediction. It is shown that for the mesoscale, the parameter has the effect of decreasing both the frequency and amplitude of the gravity wave perturbation response to small-scale impulses in forcing and to unbalanced initial conditions. This allows a modeler to choose a length scale below which gravity wave generation is suppressed. A weakness of the approach is that the hydrostatic adjustment process is slowed down. The analysis indicates that the parameter does not have an effect on the Rossby waves, the larger horizontal-scale gravity waves, nor on forced solutions such as those created by heating. The bounded derivative initialization is discussed. Since the speeds of the vertical acoustic waves are decreased, quasi-nonhydrostatic models can calculate the vertical equations explicitly and still meet the Courant-Friedrichs-Levy criteria. It is concluded that the unique characteristics of quasi-nonhydrostatic models may make them valuable in mesoscale weather prediction, particularly of clouds and precipitation."
"35572026100;6603195572;57193882808;6701670597;","Asymptotic approaches to convective quasi-equilibrium",2000,"10.1002/qj.49712656615","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033861299&doi=10.1002%2fqj.49712656615&partnerID=40&md5=b928834ea6927ddd39f1ed6fa529c735","The physical principle of convective quasi-equilibrium proposed by Arakawa and Schubert states that the atmosphere is effectively adjusted to equilibrium by an active role of convective heating against large-scale forcing (physical convective quasi-equilibrium, or PCQ). A simple consequence of this principle is that the rate of change of the thermodynamic field (typically measured by the convective available potential energy (CAPE)) is much smaller than the rate of change of the large-scale forcing (diagnostic convective quasi-equilibrium, or DCQ). Such a diagnostic state is generally observed in the tropical atmosphere at the synoptic-scale, and this is often taken as a proof for the physical mechanisms behind Arakawa and Schubert's convective quasi-equilibrium: however, theoretically, there are several alternative physical mechanisms that are also able to establish this diagnostic state. The paper examines the approach of the tropical atmospheric system to DCQ with increasing time-scale in order to distinguish various alternatives to PCQ. The latter predicts that the system approaches DCQ exponentially with a time-scale characteristic of convection. However, the alternatives considered in the paper predict algebraic asymptotes to DCQ with increasing time-scale. First it is demonstrated that PCQ is not required to achieve DCQ by considering a linear primitive-equation system with arbitrary convective heating, in which the roles of convective heating and large-scale forcing are completely reversed; algebraic asymptotes are achieved. An even simpler analogue is to assume that the rate of generating CAPE is controlled by white-noise forcing. More generally, such an algebraic asymptote is obtained by any system with a power-law spectrum both for CAPE and large-scale forcing, although a restriction must be applied to ensure a decreasing asymptote with increasing time-scale. The approach to DCQ is examined for both the Maritime Continent Thunderstorm Experiment data and cloud-resolving model simulation data, and both indicate no tendency for exponential adjustments in the short time limit."
"8152726300;6603585706;7003971889;","Vertical structure of convective heating and the three-dimensional structure of the forced circulation on an equatorial beta plane",2000,"10.1175/1520-0469(2000)057<2169:VSOCHA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034233723&doi=10.1175%2f1520-0469%282000%29057%3c2169%3aVSOCHA%3e2.0.CO%3b2&partnerID=40&md5=df67bf1c6c0bd863662571f7819916ed","In this paper, the three-dimensional structure of the thermally forced atmosphere on an equatorial β plane is investigated. Special emphasis is placed on the relations between the vertical structure of heating and the horizontal structure of the forced response. By solving the vertical eigenvalue-eigenfunction problem in a vertically semi-infinite domain, the authors obtain a complete set of vertical eigenfunctions that includes a single barotropic (external) mode and a continuous spectrum of baroclinic (internal) modes. These eigenfunctions are used to decompose vertical heating profiles for two types of tropical heating: 1) deep heating representing the convective plume (CP) heating and 2) shallow heating representing mature cloud (MC) cluster heating. By examining the spectral energy density of the heating profile, the contributions of each vertical mode (spectral interval) to the overall structure are explored for each case, and the difference between the responses to these two profiles of heating is discussed. A dry spectral primitive equation model of the atmosphere is employed to verify the analytical results. The results from both the analytical approach and the numerical simulations are consistent in showing that the vertical structure of the heating is fundamental to the structure of the forced response. The CP is deep relative to the MC. Thus, the CP projects onto the vertical eigenfunctions of relatively larger equivalent depth more so than does the MC. As a result, the CP-forced signals propagate away from the heat source much faster than those forced by the MC. Hence, when the atmosphere is subjected to the same linear dampings (Rayleigh friction and Newtonian cooling), the spatial (mainly in the horizontal) decay rate of the CP-forced signals is significantly smaller than that of the MC-forced signals, and the CP-forced signals extend farther. To what extent a shallow-water system of a specified vertical mode (e.g., the Gill model) can approximate the three-dimensional response is also examined. Results show that the effective gravity wave speed of the multimode system varies greatly with location. Hence, it is extremely difficult to select a globally suitable equivalent depth so that a one-mode shallow-water system can approximate the spatially three-dimensional structure of the response to a given heating.In this paper, the three-dimensional structure of the thermally forced atmosphere on an equatorial β plane is investigated. Special emphasis is placed on the relations between the vertical structure of heating and the horizontal structure of the forced response. By solving the vertical eigenvalue-eigenfunction problem in a vertically semi-infinite domain, the authors obtain a complete set of vertical eigenfunctions that includes a single barotropic (external) mode and a continuous spectrum of baroclinic (internal) modes. These eigenfunctions are used to decompose vertical heating profiles for two types of tropical heating: 1) deep heating representing the convective plume (CP) heating and 2) shallow heating representing mature cloud (MC) cluster heating. By examining the spectral energy density of the heating profile, the contributions of each vertical mode (spectral interval) to the overall structure are explored for each case, and the difference between the responses to these two profiles of heating is discussed. A dry spectral primitive equation model of the atmosphere is employed to verify the analytical results. The results from both the analytical approach and the numerical simulations are consistent in showing that the vertical structure of the heating is fundamental to the structure of the forced response. The CP is deep relative to the MC. Thus, the CP projects onto the vertical eigenfunctions of relatively larger equivalent depth more so than does the MC. As a result, the CP-forced signals propagate away from the heat source much faster than those forced by the MC. Hence, when the atmosphere is subjected to the same linear dampings (Rayleigh friction and Newtonain cooling), the spatial (mainly in the horizontal) decay rate of the CP-forced signals is significantly smaller than that of the MC-forced signals, and the CP-forced signals extend farther. To what extent a shallow-water system of a specified vertical mode (e.g., the Gill model) can approximate the three-dimensional response is also examined. Results show that the effective gravity wave speed of the multimode system varies greatly with location. Hence, it is extremely difficult to select a globally suitable equivalent depth so that a one-mode shallow-water system can approximate the spatially three-dimensional structure of the response to a given heating."
"7005599540;7004082836;6602668568;6701791841;","Seasonal changes in the fraction of global radiation retained as net all-wave radiation and their hydrological implications [Les variations saisonnières de la fraction du rayonnement global retenue dans le rayonnement net et leurs implications hydrologiques]",2000,"10.1080/02626660009492369","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034306558&doi=10.1080%2f02626660009492369&partnerID=40&md5=53d3cd853feb974f3da945787714770d","High linear correlation between concurrent measurements of net all-wave radiation Q*, and global incoming short-wave radiation Eg↓ was found for hourly, daytime and 24-h totals measured over a grassland catchment in the subhumid climate region of southeastern Australia. Five years of daily measurements were used to study the temporal variability in the fraction of incoming short-wave radiation retained at the surface as net all-wave radiation. When values of ξ = [Sgrave]Q*/[Sgrave]Eg↓ are calculated from 24-h totals and are plotted against date, the results reveal strong day-to-day and seasonal variability in ξ. Analysis indicated that the ξ ratio was largely determined by data, latitude and cloudiness, whilst the nature of the underlying surface appeared to play a less important role. Data from four other grassland sites in Australia, New Caledonia, Denmark and Ireland yielded a general relationship for estimating ξ from day length. Values of [Sgrave]Q* may thus be obtained from [Sgrave]Eg↓ observations using (a) a single regression between [Sgrave]Q* and [Sgrave]Eg↓ (b) monthly ξ values derived from measurements; or (c) monthly ξ values estimated from day length. All three approaches give estimates of [Sgrave]Q* with error terms similar to those of measurements of net all-wave radiation and those found when [Sgrave]Q* was estimated climatologically from the individual elements of the surface radiation balance—the standard method of obtaining this rarely measured but hydrologically important parameter. The hydrological impact of different methods of obtaining [Sgrave]Q* was demonstrated using the semi-distributed VIC catchment model to compute potential evapotranspiration for the 26 km2 Lockyersleigh catchment near Goulburn, New South Wales, Australia. The limited hydrological impact found is attributed to the fact that actual evapotranspiration in this subhumid catchment is limited by the strength of the soil water source rather than that of the atmospheric sink-potential evapotranspiration. © 2000 Taylor &amp; Francis Group, LLC."
"7201483081;","Dynamical climatology of the NASA Langley Research Center Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model",2000,"10.1029/2000JD900248","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034456043&doi=10.1029%2f2000JD900248&partnerID=40&md5=abed95c8aef638b114ae9d5f12913769","A comparison of the NASA Langley Research Center (LaRC) Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model's dynamical characteristics with assimilated data sets and observations is presented to demonstrate the ability of the model to represent the dynamical characteristics of Earth's troposphere and stratosphere. The LaRC IMPACT model is a coupled chemical/dynamical general circula-tion model (GCM) of the Earth's atmosphere extending from the surface to the lower mesosphere. It has been developed as a tool for assessing the effects of chemical, dynamical, and radiative coupling in the stratosphere on the Earth's climate. The LaRC IMPACT model winds and temperatures are found to be in fairly good agreement with Upper Atmospheric Research Satellite (UARS) United Kingdom Meteorological Office (UKMO) assimilated winds and temperatures in the lower stratosphere. The model upper stratospheric zonal mean temperatures are also in good agreement with the UARS-UKMO climatology except for a cold winter pole which results from the upward extension of the cold vortex temperatures and an elevated winter stratopause in the model. The cold pole bias is consistent with the overprediction of the winter stratospheric jet strength, and is characteristic of stratospheric GCMs in general. The model northern and southern hemisphere stratospheric eddy heat and momentum fluxes are within the expected interannual variability of the UARS-UKMO climatology. The combined effects of water vapor transport, radiative, convective, and planetary boundary layer parameterizations are shown to produce tropospheric winds and circulation statistics that are in good agreement with the UARS-UKMO climatology, although the model tropopause and upper tropospheric temperatures are generally cold relative to the UARS-UKMO temperatures. Comparisons between the model and UARS-UKMO climatology indicate that the model does a reason-able job in reproducing the frequency of observed synoptic-scale storms during the northern and southern hemisphere winters. Generally good agreement is found between the model and observations in the distribution of outgoing longwave radiation and precipitable water. However, the model precipitation and cloud distributions are influenced by spectral truncation errors which indicate that the T32 spectral resolution of the model is probably not adequate to accurately represent coupling between localized convection and large-scale water vapor transport. The agreement between the observed and model stratospheric circulation and temperatures, reasonableness of the model stratospheric wave driving, and stability of the model climatology provides confidence that the LaRC IMPACT model is appropriate for multiyear coupled radiation/chemistry/dynamics studies of the stratosphere."
"7402900768;7103128585;6504161035;","Observations of the entrainment zone in a rapidly entraining boundary layer",2000,"10.1175/1520-0469(2000)057<3145:OOTEZI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034277784&doi=10.1175%2f1520-0469%282000%29057%3c3145%3aOOTEZI%3e2.0.CO%3b2&partnerID=40&md5=5aab2c583b3c674d37ffeb0bfad2254a","High-rate turbulence data collected by the National Center for Atmospheric Research Electra aircraft on 13 January 1998 over Lake Michigan during the Lake-Induced Convection Experiment are analyzed to explore the turbulence dynamics of the entrainment zone of a rapidly entraining convective boundary layer. Horizontal flight legs combined with the gentle slope of the lake-enhanced boundary layer top yield high-resolution profiles through the entrainment zone. Data analysis used a new maximally overlapping, subleg, Reynolds decomposition algorithm to compute first-, second-, and third-moment statistics for each flight leg. Then, a compositing algorithm using 25 bins took like statistics from each flight leg and created smoothly varying curves that captured the variation of each statistic across the upper mixed layer and entrainment zone. The analysis results reveal a conventional convective boundary layer below and a nonturbulent free atmosphere above a well-resolved entrainment zone. In the entrainment zone, temperature and moisture skewness curves show that the last identifiable free atmosphere effects extend down well below the zero crossing of heat flux. Third-moment statistics reveal considerable height dependence of the entrainment zone dynamics.High-rate turbulence data collected by the National Center for Atmospheric Research Electra aircraft on 13 January 1998 over Lake Michigan during the Lake-Induced Convection Experiment are analyzed to explore the turbulence dynamics of the entrainment zone of a rapidly entraining convective boundary layer. Horizontal flight legs combined with the gentle slope of the lake-enhanced boundary layer top yield high-resolution profiles through the entrainment zone. Data analysis used a new maximally overlapping, subleg, Reynolds decomposition algorithm to compute first-, second-, and third-moment statistics for each flight leg. Then, a compositing algorithm using 25 bins took like statistics from each flight leg and created smoothly varying curves that captured the variation of each statistic across the upper mixed layer and entrainment zone. The analysis results reveal a conventional convective boundary layer below and a nonturbulent free atmosphere above a well-resolved entrainment zone. In the entrainment zone, temperature and moisture skewness curves show that the last identifiable free atmosphere effects extend down well below the zero crossing of heat flux. Third-moment statistics reveal considerable height dependence of the entrainment zone dynamics."
"57198472289;7501757094;","A regional model simulation of the 1991 severe precipitation event over the Yangtze-Huai River valley. Part II: Model bias",2000,"10.1175/1520-0442(2000)013<0093:ARMSOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034081711&doi=10.1175%2f1520-0442%282000%29013%3c0093%3aARMSOT%3e2.0.CO%3b2&partnerID=40&md5=e8a84b791e196e7c5371c2d0b09407dd","This is the second part of a study investigating the 1991 severe precipitation event over the Yangtze-Huai River valley (YHRV) in China using both observations and regional model simulations. While Part I reported on the Mei-yu front and its association with large-scale circulation, this study documents the biases associated with the treatment of the lateral boundary in the regional model. Two aspects of the biases were studied: the driving field, which provides large-scale boundary forcing, and the coupling scheme, which specifies how the forcing is adopted by the model. The former bias is defined as model uncertainty because it is not related to the model itself, while the latter bias (as well as those biases attributed to other sources) is referred to as model error. These two aspects were examined by analyzing the regional model simulations of the 1991 summer severe precipitation event over YHRV using different driving fields (ECMWF-TOGA objective analysis, ECMWF reanalysis, and NCEP-NCAR reanalysis) and coupling scheme (distribution function of the nudging coefficient and width of the buffer zone). Spectral analysis was also used to study the frequency distribution of the bias. The analyses suggest that the 200-hPa winds. 500-hPa geopotential height, and 850-hPa winds and water vapor mixing ratio, which have dominant influences on Mei-yu evolution, are sensitive to large-scale boundary forcing. In particular the 500-hPa geopotential height, and 850-hPa water vapor mixing ratio near the Tibetan Plateau and over the western Pacific Oceans are highly dependent on the driving field. On the other hand, the water vapor in the lower troposphere, wind at all levels, and precipitation pattern are much more affected by the treatment of nudging in the coupling scheme. It is interesting to find that the two commonly used coupling schemes, the lateral boundary coupling and the spectral coupling, provide similar large-scale information to the simulation domain when the former scheme used a wider buffer zone and stronger nudging coefficient. Systematical model errors, existing in the north of the simulation domain, are caused by the overprediction of low-level inversion stratiform clouds. The analyses further indicate that the model mesoscale signal is not significantly influenced by the different treatments of the nudging procedure. However, it is also shown that the model performance, especially the monthly mean precipitation and its spatial pattern, is substantially improved with the increase of buffer zone width and nudging coefficient.This is the second part of a study investigating the 1991 severe precipitation event over the Yangtze-Huai River valley (YHRV) in China using both observations and regional model simulations. While Part I reported on the Mei-yu front and its association with large-scale circulation, this study documents the biases associated with the treatment of the lateral boundary in the regional model. Two aspects of the biases were studied: the driving field, which provides large-scale boundary forcing, and the coupling scheme, which specifies how the forcing is adopted by the model. The former bias is defined as model uncertainty because it is not related to the model itself, while the latter bias (as well as those biases attributed to other sources) is referred to as model error. These two aspects were examined by analyzing the regional model simulations of the 1991 summer severe precipitation event over YHRV using different driving fields (ECMWF-TOGA objective analysis, ECMWF reanalysis, and NCEP-NCAR reanalysis) and coupling scheme (distribution function of the nudging coefficient and width of the buffer zone). Spectral analysis was also used to study the frequency distribution of the bias. The analyses suggest that the 200-hPa winds, 500-hPa geopotential height, and 850-hPa winds and water vapor mixing ratio, which have dominant influences on Mei-yu evolution, are sensitive to large-scale boundary forcing. In particular the 500-hPa geopotential height, and 850-hPa water vapor mixing ratio near the Tibetan Plateau and over the western Pacific Oceans are highly dependent on the driving field. On the other hand, the water vapor in the lower troposphere, wind at all levels, and precipitation pattern are much more affected by the treatment of nudging in the coupling scheme. It is interesting to find that the two commonly used coupling schemes, the lateral boundary coupling and the spectral coupling, provide similar large-scale information to the simulation domain when the former scheme used a wider buffer zone and stronger nudging coefficient. Systematical model errors, existing in the north of the simulation domain, are caused by the overprediction of low-level inversion stratiform clouds. The analyses further indicate that the model mesoscale signal is not significantly influenced by the different treatments of the nudging procedure. However, it is also shown that the model performance, especially the monthly mean precipitation and its spatial pattern, is substantially improved with the increase of buffer zone width and nudging coefficient."
"6507481371;7003614389;","Modelling chemistry in aircraft plumes 2: The chemical conversion of NO(x) to reservoir species under different conditions",2000,"10.1016/S1352-2310(00)00155-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034238178&doi=10.1016%2fS1352-2310%2800%2900155-2&partnerID=40&md5=f64591e58f014db17d08dd77190b3563","An expanding plume model with chemistry has been used to study the chemical conversion of nitrogen oxides to reservoir species in aircraft plumes under various conditions. A plume from a B747 was studied, where the NO(x) emission index was 26.1gkg-1. Several sensitivity tests were performed for emissions at 07 UT at 50°N under summer conditions. The amount of NO(x) remaining in the plume after 15h was between 58 and 69%, assuming background concentrations of ozone and NO(x) ranging from 50 to 200ppb and 50 to 200ppt, respectively. A somewhat higher range in the chemical conversion of NO(x) was calculated when changing the temperature from 200 to 240K. The remaining NO(x) in the plume increased to 90% in a study where the aircraft emissions were released in air masses already exposed to aircraft emissions some hours before. The rate of chemical conversion of NO(x) to reservoir species was highly dependent on the number of sunlit hours during the 15h period. The diurnal, seasonal and latitudinal variations in the chemical conversion of NO(x) to reservoir species were studied. As a first approximation, the conversion rates can be used to modify the aircraft NO(x) emissions at cruise altitudes used in mesoscale models. Copyright (C) 2000 Elsevier Science B.V.An expanding plume model with chemistry has been used to study the chemical conversion of nitrogen oxides to reservoir species in aircraft plumes under various conditions. A plume from a B747 was studied, where the NOx emission index was 26.1 g kg-1. Several sensitivity tests were performed for emissions at 07 UT at 50°N under summer conditions. The amount of NOx remaining in the plume after 15 h was between 58 and 69%, assuming background concentrations of ozone and NOx ranging from 50 to 200 ppb and 50 to 200 ppt, respectively. A somewhat higher range in the chemical conversion of NOx was calculated when changing the temperature from 200 to 240 K. The remaining NOx in the plume increased to 90% in a study where the aircraft emissions were released in air masses already exposed to aircraft emissions some hours before. The rate of chemical conversion of NOx to reservoir species was highly dependent on the number of sunlit hours during the 15 h period. The diurnal, seasonal and latitudinal variations in the chemical conversion of NOx to reservoir species were studied. As a first approximation, the conversion rates can be used to modify the aircraft NOx emissions at cruise altitudes used in mesoscale models."
"7401483669;57164240600;7202377834;","The relative utility of current observation systems to global-scale NWP forecasts",2000,"10.1256/smsqj.56804","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033821141&doi=10.1256%2fsmsqj.56804&partnerID=40&md5=af1a08e7df297e6b294065129786485f","We study 20 cases in which 60-hour Numerical Weather Prediction (NWP) of specific synoptic events have been markedly improved by observations made during the final 15 hours prior to the forecast initial time. For each case, the observing systems which played major roles in improving the accuracy of the forecast mean-sea-level pressure (m.s.l.p.) field are identified using a series of Observation System Experiments. The relative utility of each observation type is then assessed according to the frequency, over all cases, with which it delivers a major beneficial impact. The method of multiple case-study employed has the advantage that observation value is assessed according to the benefit delivered to forecasts of events (e.g. cyclogenesis) which are of prime importance to operational meteorology. The method, therefore, provides a useful complement to the conventional statistical approach which typically yields an 'average' benefit, calculated for all regimes (both active and 'quiet') occurring over a given period within a specific geographical region. The cases are selected from the most significant data-impact events detected in routine operational forecasts of m.s.l.p., for Europe and North America, during the period September 1993 to December 1995. Results indicate that, for weather systems developing over North America, radiosonde and aircraft reports contribute major forecast benefits most often, confirming their key role in the North American network. These two observing systems contribute with similar frequency, suggesting that the effectiveness of the less abundant radiosonde reports is boosted significantly by their profile format. Surface data and cloud-track winds are the next most frequent contributors. For weather systems developing over the North Pacific and North Atlantic, aircraft winds contribute forecast benefits most frequently, and by a wide margin. Conventional surface data also play a key role. Comparison of the utility of wind and temperature data suggests that, on average, the benefit of wind profiles is somewhat greater than that of temperature profiles, and that, in levels above ~400 hPa, wind data are considerably more valuable than temperature data. The results give insights which can be used to guide the rationalization of existing networks within the northern hemisphere mid latitudes, and the following recommendations are made with a view to improving NWP over the European area. Acquire more aircraft data over North Atlantic routes and over Europe (including reports during climb and descent). However, caution must be exercised if aircraft data are used to replace profile information from radiosondes. Deploy more surface observations (e.g. drifting buoys) and shipborne radiosonde ascents over the North Atlantic. Make more use of pattern-tracking techniques for deriving 'clear-air' wind data from satellite water-vapour imagery. Continue investigation of the effectiveness of observations 'targeted' on objectively defined regions where model errors are predicted to grow most rapidly."
"22941176100;7003926380;","Environmental variability during TOGA COARE",2000,"10.1175/1520-0469(2000)057<2333:EVDTC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034253318&doi=10.1175%2f1520-0469%282000%29057%3c2333%3aEVDTC%3e2.0.CO%3b2&partnerID=40&md5=76a13c78ba28e29208a1fe0ae1e90565","This study provides quantitative estimates of the thermodynamic and kinematic structures of the troposphere during various convective regimes observed during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. The data source is the upper air soundings from six stations in the intensive flux array. A correction algorithm has been applied to the humidity data to remove biases between the stations. The data are analyzed using the nonhierarchical clustering method known as k means. Eleven thermodynamic clusters and 20 kinematic clusters are selected. The thermodynamic clusters are grouped into four general categories based on their midtropospheric equivalent potential temperature. Deep convective activity varies with the thermodynamic structure of the environment. When the 'dry intrusion' group is observed, convection is suppressed. The 'fair weather' category corresponds to undisturbed periods with light winds and small mesoscale convective systems (MCSs). The largest MCSs and the majority of the rainfall occur with the 'active' and 'convective recovery' categories. The kinematic clusters are also divided into four general categories based on the strength, direction, and depth of the low-level zonal flow. The timing of the clusters is related to the intraseasonal oscillation (ISO). Dry phases of the ISO are characterized by the 'low-level easterly' category. During transition periods between the easterly and westerly phases of the ISO, the 'calm' category is often seen. The 'moderate shear westerly' group is seen just before the strongest westerlies. The majority of the clusters fall into the 'strong shear westerly' group, associated with the peak westerly phase of the ISO.This study provides quantitative estimates of the thermodynamic and kinematic structures of the troposphere during various convective regimes observed during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. The data source is the upper air soundings from six stations in the intensive flux array. A correction algorithm has been applied to the humidity data to remove biases between the stations. The data are analyzed using the nonhierarchical clustering method known as k means. Eleven thermodynamic clusters and 20 kinematic clusters are selected. The thermodynamic clusters are grouped into four general categories based on their midtropospheric equivalent potential temperature. Deep convective activity varies with the thermodynamic structure of the environment. When the 'dry intrusion' group is observed, convection is suppressed. The 'fair weather' category corresponds to undisturbed periods with light winds and small mesoscale convective systems (MCSs). The largest MCSs and the majority of the rainfall occur with the 'active' and 'convective recovery' categories. The kinematic clusters are also divided into four general categories based on the strength, direction, and depth of the low-level zonal flow. The timing of the clusters is related to the intraseasonal oscillation (ISO). Dry phases of the ISO are characterized by the 'low-level easterly' category. During transition periods between the easterly and westerly phases of the ISO, the 'calm' category is often seen. The 'moderate shear westerly' group is seen just before the strongest westerlies. The majority of the clusters fall into the 'strong shear westerly' group, associated with the peak westerly phase of the ISO."
"6701854276;57205892673;7402373111;","A satellite-derived upper-tropospheric water vapor transport index for climate studies",2000,"10.1175/1520-0450(2000)039<0015:ASDUTW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034035928&doi=10.1175%2f1520-0450%282000%29039%3c0015%3aASDUTW%3e2.0.CO%3b2&partnerID=40&md5=d3c59e636309e2983d135ff18929d0e4","A new approach is presented to quantify upper-level moisture transport from geostationary satellite data. Daily time sequences of Geostationary Operational Environmental Satellite GOES-7 water vapor imagery were used to produce estimates of winds and water vapor mixing ratio in the cloud-free region of the upper troposphere sensed by the 6.7-μm water vapor channel. The winds and mixing ratio values were gridded and then combined to produce a parameter called the water vapor transport index (WVTI), which represents the magnitude of the two-dimensional transport of water vapor in the upper troposphere. Daily grids of WVTI, meridional moisture transport, mixing ratio, pressure, and other associated parameters were averaged to produce monthly fields for June, July, and August (JJA) of 1987 and 1988 over the Americas and surrounding oceanic regions. The WVTI was used to compare upper-tropospheric moisture transport between the summers of 1987 and 1988, contrasting the latter part of the 1986/87 El Niño event and the La Niña period of 1988. A similar product derived from the National Centers for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) 40-Year Reanalysis Project was used to help to validate the index. Although the goal of this research was to describe the formulation and utility of the WVTI, considerable insight was obtained into the interannual variability of upper-level water vapor transport. Both datasets showed large upper-level water vapor transport associated with synoptic features over the Americas and with outflow from tropical convective systems. Minimal transport occurred over tropical and subtropical high pressure regions where winds were light. Index values from NCEP-NCAR were 2-3 times larger than that determined from GOES. This difference resulted from large zonal wind differences and an apparent overestimate of upper-tropospheric moisture in the reanalysis model. A comparison of the satellite-derived monthly values between the summers of 1987 and 1988 provided some insight into the impact of the ENSO event on upper-level moisture and its transport during the period. During July 1987, a large portion of the Tropics in the eastern Pacific Ocean and Caribbean Sea was dominated by strong vapor transport in excess of 4.0 g kg-1 m s-1, with relatively small amounts in the other months. JJA 1988 transport values reached similar magnitude and showed similar patterns for all three months. The meridional transport of upper-level water vapor indicated large poleward transport from the Tropics to the higher latitudes. This transport favored the Southern Hemisphere, with large transport occurring south of the ITCZ, which extended across the eastern Pacific and northern South America. Zonally averaged monthly transport values were shown to provide a simple way to quantify the monthly and interannual changes in water vapor transport. Zonally averaged WVTI values peaked in the Southern Hemisphere subtropics during both austral winters. In the Tropics, a single, more-pronounced peak located over the equator and south latitudes occurred in 1988 as opposed to a dual peak in 1987. The second peak around 20°N latitude is consistent with findings of others in which upper-tropospheric winds were noted to be stronger in this region during warm ENSO events. Zonally averaged meridional transport was southward for all summer months and was stronger in 1988. The asymmetric nature of the zonally averaged meridional transport (more southerly water vapor transport) was enhanced during JJA 1988, thus indicating a stronger upper-level branch of the Hadley circulation during this notably strong La Niña period."
"7003591311;25953950400;7005968859;7405959144;","The impact of giant cloud condensation nuclei on drizzle formation in stratocumulus: Implications for cloud radiative properties",1999,"10.1175/1520-0469(1999)056<4100:TIOGCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033573401&doi=10.1175%2f1520-0469%281999%29056%3c4100%3aTIOGCC%3e2.0.CO%3b2&partnerID=40&md5=0be211b5be6ccf271aa5f2dbb64373ea","The impact of giant and ultragiant cloud condensation nuclei (&gt;5-jum radius) on drizzle formation in stratocumuli is investigated within a number of modeling frameworks. These include a simple box model of collection, a trajectory ensemble model (comprising an ensemble of Lagrangian parcel models), a 2D eddy-resolving model, and a 3D large-eddy simulation model. Observed concentrations of giant cloud condensation nuclei (GCCN) over the ocean at ambient conditions indicate that 20-/un radius haze particles exist in concentrations of between 10'4 and 10~2 cm~3, depending on ambient wind speed and seastate. It is shown that these concentrations are sufficient to move a nonprecipitating stratocumulus into a precipitating state at typical cloud condensation nucleus (CCN) concentrations of 50 to 250 cm'3, with higher concentrations of GCCN being required at higher CCN concentrations. However, at lower CCN concentrations, drizzle is often active anyway and the addition of GCCN has little impact. At high CCN concentrations, drizzle development is slow and GCCN have the greatest potential for enhancing the collection process. Thus, although drizzle production decreases with increasing CCN concentration, the relative impact of GCCN increases with increasing CCN concentration. It is also shown that in the absence of GCCN, a shift in the modal radius of the CCN distribution to larger sizes suppresses drizzle because larger modal radii enable the activation of larger droplet number concentrations. Finally, calculations of the impact of GCCN on cloud optical properties are performed over a range of parameter space. Results indicate that the presence of GCCN moderates the effect of CCN on optical properties quite significantly. In the absence of GCCN, an increase in CCN from 50 to 150 cm3 results in a threefold increase in albedo; when GCCN exist at a concentration of 103 cm3, the increase in albedo is only twofold. Thus the variable presence of GCCN represents yet another uncertainty in estimating the influence of anthropogenic activity on climate. © 1999 American Meteorological Society."
"7006332857;7402469179;","Statistical downscaling of subgridscale precipitation",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-27844591414&partnerID=40&md5=48926972b035e9dd30ce6b98cba541b4","Deficiencies exist in the detailed description of precipitation in climate models and numerical weather prediction models. Therefore it is necessary to develop concepts for downscaling precipitation depending on the synoptic situation. Subgridscale precipitation which is not influenced by fronts or orography is considered (e.g. airmass showers) and a conceptual model has been developed which gives information about precipitating cells such as their intensity. Based on case studies carried out with data from OMNIS, a now-casting information system developed by the German Military Geophysical Office, and the work of Austin & Houze (1972), a modified equation for determining the statistics of precipitation intensities for single cells for cloud depth and temperature at 850 hPa is shown. Incorporating the temperature at 850 hPa leads to a wider range of expected intensities than from cloud depth alone. It is shown that the precipitation amount at ground level is also influenced by the temperature at 850 hPa."
"6602326421;56283400100;","Unstable behaviour of an upper ocean-atmosphere coupled model: Role of atmospheric radiative processes and oceanic heat transport",1999,"10.1007/s003820050320","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033368116&doi=10.1007%2fs003820050320&partnerID=40&md5=2551ce4295e4828a443a4ead92489bc4","We describe the initial bias of the climate simulated by a coupled ocean-atmosphere model. The atmospheric component is a state-of-the-art atmospheric general circulation model, whereas the ocean component is limited to the upper ocean and includes a mixed layer whose depth is computed by the model. As the full ocean general circulation is not computed by the model, the heat transport within the ocean is prescribed. When modifying the prescribed heat transport we also affect the initial drift of the model. We analyze here one of the experiments where this drift is very strong, in order to study the key processes relating the changes in the ocean transport and the evolution of the model's climate. In this simulation, the ocean surface temperature cools by 1.5 °C in 20 y. We can distinguish two different phases. During the first period of 5 y, the sea surface temperatures become cooler, particularly in the intertropical area, but the outgoing longwave radiation at the top-of-the-atmosphere increases very quickly, in particular at the end of the period. An off-line version of the model radiative code enables us to decompose this behaviour into different contributions (cloudiness, specific humidity, air and surface temperatures, surface albedo). This partitioning shows that the longwave radiation evolution is due to a decrease of high level cirrus clouds in the intertropical troposphere. The decrease of the cloud cover also leads to a decrease of the planetary albedo and therefore an increase of the net short wave radiation absorbed by the system. But the dominant factor is the strong destabilization by the longwave cooling, which is able to throw the system out of equilibrium. During the remaining of the simulation (second phase), the cooling induced by the destabilization at the top-of-the-atmosphere is transmitted to the surface by various processes of the climate system. Hence, we show that small variations of ocean heat transport can force the model from a stable to an unstable state via atmospheric processes which arise when the tropics are cooling. Even if possibly overestimated by our GCM, this mechanism may be pertinent to the maintenance of present climatic conditions in the tropics. The simplifications inherent in our model's design allow us to investigate the mechanism in some detail."
"6603867545;7103311365;6602863880;56614117900;","Surface meteorological conditions at benthic disturbance experiment site - INDEX area during austral winter 1997",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033324382&partnerID=40&md5=7ac2110c73f4fa05f4d3208b6e65059e","Benthic Disturbance Experiment surveys in the Central Indian Ocean Basin yielded baseline data on surface meteorological conditions during June and August, 1997 together with sea surface temperature (SST) and cloud data to estimate the air-sea heat fluxes and net surface heat gain. Maximum sunshine duration was 1 hour/day in June and 30 minutes/day in August. SST decreased from 28.2 °C in June to 25.8 °C in August. Southeasterly winds of speed 10 m/s during June contributed to a mean latent heat flux of 220 W/m2, leading to net surface heat loss (100 W/m2) in June and near heat balance in August. Temporal variation of weather elements and the heat budget parameters showed fluctuations of period 10-13 days in June and 7-8 days in August. Owing to low sunshine duration (&lt;1 hour/day) and light attenuation due to surface discharge of mining reject during austral winter, diminishing of light availability in the upper ocean is possible."
"7102062952;7202456825;7402353721;7003394933;7004211803;7006408696;7004425841;6602151649;7101612696;6603583944;","Biogenic hydrocarbon emissions and landcover/climate change in a subtropical savanna",1999,"10.1016/S1464-1909(99)00062-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033390942&doi=10.1016%2fS1464-1909%2899%2900062-3&partnerID=40&md5=3d32f092d627a3b18d2ba3284c827ca5","Biogenic non-methane hydrocarbon (NMHC) emissions strongly influence the chemical composition of the troposphere. Thus, variations in emissions of these compounds are expected to cause changes in concentrations of important atmospheric trace gases. Here, we assess the relative magnitude of potential changes in NMHC (e.g., isoprene and monoterpene) emissions using field flux measurements from a subtropical savanna parkland/thorn woodland site in conjunction with model predictions of climate and landcover change. NMHC emissions of about 40 plant species were characterized. Grasses, as a group, had low emission rates. Several common woody species had high emission rates. However, there was little evidence of emissions being consistently related to woody plant taxonomy, growthform or functional groups. Above-canopy measurements were used to validate modeled isoprene flux predictions of about 2 mg C m-2 h-1 for savanna parkland/thorn woodland and ca. 0.7 mg C m-2 h-1 for the regional landscape, which is a mixture of savanna parkland/thorn woodland and cropland. Linkage of the biogenic emissions model with a plant succession model indicated that landcover change since the early 1800s has elicited a 3-fold increase in total NMHC emissions. This increase reflected changes in vegetation species composition (from domination by grasses which were typically 'low emitters', to shrubs and trees, many of which were 'high emitters') and increases in foliar density. Field measurements on two common shrub species indicated that isoprene emission increased exponentially with increases in leaf temperature from 20 to 40°C and were not suppressed by drought stress. Accordingly, our model predicted that projected increases in ambient temperature (3 to 6°C) emissions could produce a 2-fold increase in biogenic NMHC emissions. Cloud cover, precipitation, relative humidity, and winds also exerted some control over NMHC emissions, but their influence was highly variable and difficult to estimate. Although our results are specific to southern Texas USA, they indicate the magnitude of change in NMHC emissions that could occur at other locations when climate and vegetation composition are altered."
"6701467379;35518435600;56472932500;","Evaluation of secondary organic aerosol formation in winter",1999,"10.1016/S1352-2310(99)00310-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033486411&doi=10.1016%2fS1352-2310%2899%2900310-6&partnerID=40&md5=e86859d4eafaebb6289eb888f57eafbb","Three different methods are used to predict secondary organic aerosol (SOA) concentrations in the San Joaquin Valley of California during the winter of 1995-1996 [Integrated Monitoring Study, (IMS95)]. The first of these methods estimates SOA by using elemental carbon as a tracer of primary organic carbon. The second method relies on a Lagrangian trajectory model that simulates the formation, transport, and deposition of secondary organic aerosol. The model includes a recently developed gas-particle partitioning mechanism. Results from both methods are in good agreement with the chemical speciation of organic aerosol during IMS95 and suggest that most of the OC measured during IMS95 is of primary origin. Under suitable conditions (clear skies, low winds, low mixing heights) as much as 15-20 μg Cm-3 of SOA can be produced, mainly due to oxidation of aromatics. The low mixing heights observed during the winter in the area allow accumulation of SOA precursors and the acceleration of SOA formation. Clouds and fog slow down the production of secondary compounds, reducing their concentrations by a factor of two or three from the above maximum levels. In addition, it appears that there is significant diurnal variation of SOA concentration. A strong dependence of SOA concentrations on temperature is observed, along with the existence of an optimal temperature for SOA formation.Three different methods are used to predict secondary organic aerosol (SOA) concentrations in the San Joaquin Valley of California during the winter of 1995-1996 [Integrated Monitoring Study, (IMS95)]. The first of these methods estimates SOA by using elemental carbon as a tracer of primary organic carbon. The second method relies on a Lagrangian trajectory model that simulates the formation, transport, and deposition of secondary organic aerosol. The model includes a recently developed gas-particle partitioning mechanism. Results from both methods are in good agreement with the chemical speciation of organic aerosol during IMS95 and suggest that most of the OC measured during IMS95 is of primary origin. Under suitable conditions (clear skies, low winds, low mixing heights) as much as 15-20 μg C m-3 of SOA can be produced, mainly due to oxidation of aromatics. The low mixing heights observed during the winter in the area allow accumulation of SOA precursors and the acceleration of SOA formation. Clouds and fog slow down the production of secondary compounds, reducing their concentrations by a factor of two or three from the above maximum levels. In addition, it appears that there is significant diurnal variation of SOA concentration. A strong dependence of SOA concentrations on temperature is observed, along with the existence of an optimal temperature for SOA formation."
"6602253099;57209757800;","Rapid estimation of photosynthetically active radiation over the West African Sahel using the Pathfinder Land data set",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346863606&partnerID=40&md5=832bbba77cc0cfdc0c219858058e0267","Photosynthetically Active Radiation (PAR) is important for assessing both the impact of changing land cover on climate, and for modelling productivity on a regional scale, as well as its potential in areas that are vulnerable to food shortfalls. A relatively simple method that generates spatially comprehensive and representative values of PAR at time scales of 10-days (dekads) or longer is described, tested and implemented over a portion of West Africa. With simple equations to describe the geographical and temporal variation of global radiation receipt at the top of the atmosphere, daily cloud flags from the NOAA/NASA AVHRR Pathfinder Land Data Set (PAL) are used in conjunction with an empirical formula developed by Angstrom and constants tailored to West African conditions to estimate surface receipt of global radiation there. Ground observations of PAR from the HAPEX Sahel experiment (at 13°66' N and 2°53' E from 1992) are used to parameterise the relative sunshine duration variable in the Angstrom relation so as to minimise errors between observed and modelled PAR. Results indicate that PAR may be estimated to within 20 percent of observed values for 28 out of 36 10-day summation periods over a year. End-of-year accumulated PAR is estimated to within 1.96 percent. Normalised root mean square errors (NRMSEs) and normalised mean absolute errors (NMAEs) of 15.69 percent and 12.46 percent, respectively, were obtained for 10-day sums, with values of 10.96 percent and 8.74 percent, respectively, for monthly sums. The spatial variability of end-of-year PAR for 1992 is in accordance with what was expected. Though more accurate methods exist for achieving this, the technique is merited for its ease of application, using an accessible data set, over areas where solar irradiation measurements are lacking."
"6507763080;7004202683;7003753838;","Evaluation of a simplified dynamical rainfall forecasting model from rain events simulated using a meteorological model",1999,"10.1016/S1464-1909(99)00098-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033377842&doi=10.1016%2fS1464-1909%2899%2900098-2&partnerID=40&md5=1de630618826cc00eed99119dbf059d4","This paper presents an evaluation of a simplified dynamical model from simulated rain events. This model is based on conservation of the rainwater content of an atmospheric column and uses multi-scan radar data and surface meteorological observations. A test of the model using radar data from Oklahoma City (USA) and the Cevennes region (France) has not clearly shown the model efficiency compared to the simple extrapolation of radar observations. This statement can be explained by the limited number of rain events available for testing the model and errors inherent in radar measurements. The proposed evaluation is based on a mono-dimensional microphysical and meteorological model, which serves to simulate reference rainfall. The outputs of the meteorological model: rainwater content, cloud top temperature, surface temperature, pressure and dew point are used for initialising the simplified dynamical model as in the case of observed rain events. The evaluation of the simplified dynamical model is performed by comparing forecasts to reference rainrates. This comparison shows that the simplified dynamical model performs better than the simple extrapolation method for short lead-times up to 30 min. This time is related to the response time of the rainwater atmospheric column. For longer lead-times, the dynamics of the simplified model tends to a steady state characterised by a constant rainfall rate controlled by the source term. This result which has still to be confirmed makes the model adapted to requirements of urban hydrology."
"7102253788;","Decadal time scale trends and variability in the tropospheric circulation over the South Pole",1999,"10.1029/1999JD900483","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033610945&doi=10.1029%2f1999JD900483&partnerID=40&md5=872949862ed47912961438a764d0182a","This paper documents significant long-term changes in the tropospheric circulation and progression of the seasonal cycle over the South Pole and relates aspects of the changes to the enhanced springtime stratospheric ozone depletion of recent decades. During the winter-to-summer transition over Antarctica, the formation of the thermal tropopause above 150 hPa is now delayed by a month compared to the early 1960s. A similar delay occurs in the breakdown of the winter polar stratospheric vortex, a prerequisite to the formation of the strong summertime tropopause near 300 hPa. A delay in tropopause formation implies delays in those aspects of the transition from winter to summer in the dynamics of the troposphere that are sensitive to its upper boundary condition, including the contraction of the Rossby radius of deformation during the shallow troposphere phase of summer. Consistent with this expectation, the normal springtime decline of baroclinic-eddy activity in the lower troposphere now occurs later by a month. Similar delays occur in the time of an early summer minimum in total cloud fraction that coincides with the time of the maximum stratification between 150 and 100 hPa. In addition, the analyses reveal (1) an increase of 15 to 20% in spring and summer cloud fraction over the last four decades; (2) a separation of spring and summer cloudiness into two transport regimes with a distinct intervening minimum in cloud fraction; (3) a decadal modulation of springtime cloudiness that is coincident with decadal shifts in the directional mode of 300-hPa winds following solar minima; (4) a long-term increase in total inversion strength, inversion depth, and 650-to 300-hPa thickness; and (5) a long-term decrease in wintertime surface wind speed, surface temperature, and near-surface lapse rate. The study also introduces a covariance technique that exploits the control by continental-scale orography of synoptic and surface flow regimes, increasing the value of lower tropospheric observations for the study of climate change over Antarctica. Finally, a cautionary note arises from the apparent effect of the Weddell Polynyas and the reduction of the maximum extent of sea ice of the middle to late 1970s, with increased tropospheric and lower stratospheric temperatures and an earlier time of formation of the tropopause. This observation suggests that the occurrence of decadal and subdecadal variability in the ocean and the atmosphere of the Southern Hemisphere may obscure the detection of long-term trends in the circulation over Antarctica."
"57203053317;6603613067;7005453346;7003371432;7003931528;","Tropospheric sulfur cycle in the Canadian general circulation model",1999,"10.1029/1999JD900343","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033589492&doi=10.1029%2f1999JD900343&partnerID=40&md5=bc5198bbe7ebddd11aa68b60cc4c066b","Emission, transport, chemistry, and scavenging of the gaseous sulfur species dimethyl sulfide and sulfur dioxide (SO2) and sulfate aerosols are calculated on-line with the meteorology in the general circulation model (GCM) of the Canadian Centre for Climate Modelling and Analysis (CCCMA). Additionally, prognostic equations for cloud water and cloud ice have been introduced. The sensitivity of this sulfur cycle to differences in GCM physics and dynamics has been studied by comparing the results to those obtained with the ECHAM GCM which has a very similar sulfur cycle and cloud scheme, but a different turbulent diffusion and convection scheme. The differences in the global mean burdens of SO2 and sulfate are less than 2%. Simulated surface SO2 concentrations with CCCMA in winter as well as the seasonal cycle are in better agreement with observations at several sites than those simulated with ECHAM because of stronger boundary layer mixing in CCCMA. The simulated surface SO42- with CCCMA, however, is often higher than observed and in ECHAM. Additionally, sensitivity experiments showed that the global sulfur budgets are most sensitive to changes in the cloud cover parameterization and less sensitive to changes in pH calculation and oxidation of SO2 in convective clouds. The results of the sensitivity experiments give evidence for the importance of all of these effects on the geographical and vertical distribution of sulfur and cloud liquid water. Copyright 1999 by the American Geophysical Union."
"7202208382;57119767800;","Alternative methods for specification of observed forcing in single-column models and cloud system models",1999,"10.1029/1999JD900765","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000188971&doi=10.1029%2f1999JD900765&partnerID=40&md5=14835ec8dd588c321ec8ce367779998e","We discuss alternative methods for prescribing advective tendencies in single-column models (SCMs) and cloud system models. These include ""revealed forcing,"" in which the total advective tendency is prescribed from observations; ""horizontal advective forcing,"" in which the horizontal advective tendencies are prescribed, together with the observed vertical motion which is combined with the predicted sounding to determine the tendencies due to vertical advection; and ""relaxation forcing,"" in which the horizontal advective tendencies are computed by relaxing the sounding toward the observed upstream sounding, with a relaxation timescale determined by the time required for the wind to carry parcels across the grid column. When relaxation forcing is used, the horizontal advective tendencies can be diagnosed from the model output and compared with the corresponding observed tendencies. We present SCM results to illustrate these three forcing methods, based on data from several field experiments in both the tropics and the midlatitudes. Each method is shown to have its strengths and weaknesses. Overall, the results presented here do not show unambiguous differences between revealed forcing and horizontal advective forcing. The two methods appear to be generally comparable. Revealed forcing may therefore be preferred for its simplicity. Relaxation forcing guarantees realistic soundings of the state variables but can produce large errors in parameterized processes which are driven by rates (e.g., fluxes) rather than states. In particular, relaxation forcing gives large errors in the precipitation rate in this model. We demonstrate that relaxation forcing leads to unrealistically high (low) precipitation in versions of the model which tend to produce unrealistically dry (humid) soundings. The observed horizontal advective tendencies in the tropics are so weak, especially for temperature, that small absolute errors in the diabatic tendencies diagnosed with relaxation forcing can lead to large relative errors in the diagnosed horizontal advective tendencies. Copyright 1999 by the American Geophysical Union."
"56283400100;","Global hydrological changes associated with a perturbation of the climate system: The role of atmospheric feedbacks, their uncertainty and their validation",1999,"10.1016/S0309-1708(99)00016-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033377692&doi=10.1016%2fS0309-1708%2899%2900016-0&partnerID=40&md5=aae1b7e8ebf233ab246be4108614b5fd","The anthropogenic increase of the atmospheric greenhouse effect is expected to bring important perturbations of the climate system during the next century. The models which are used to compute scenarios of this future climate change nevertheless suffer from important uncertainties which make impossible the detailed prediction of regional impacts. Characterizing these uncertainties as precisely as possible constitutes a necessary step to assess a climate risk and realize local impact studies. We describe the manifestation of water vapour and cloud feedbacks in the present models, and show that satellite data, in particular, may constitute an important source of information to constrain more efficiently the models."
"57211224269;36655323000;","On overestimation of tropical precipitation by an atmospheric GCM with prescribed SST",1999,"10.1029/1999GL900616","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033208556&doi=10.1029%2f1999GL900616&partnerID=40&md5=692f5b10974a974848b9d68effacaa4c","We investigate how an atmospheric general circulation model (AGCM) can reproduce atmospheric aspects of climate, when the boundary conditions are prescribed. The AGCM is integrated with sea surface temperature (SST) specified from an integration of a coupled general circulation model (CGCM). A systematic difference in the mean climate is found between the AGCM and the CGCM in the tropical Pacific. This difference is apparent when and where local SST is warmest. In the CGCM, precipitation does not last long due to SST and cloud-radiation feedback. Precipitation in the AGCM, however, tends to persist longer. Results of this experiment imply that caution is needed when using an AGCM with boundary conditions derived from a CGCM for climate change studies.We investigate how an atmospheric general circulation model (AGCM) can reproduce atmospheric aspects of climate, when the boundary conditions are prescribed. The AGCM is integrated with sea surface temperature (SST) specified from an integration of a coupled general circulation model (CGCM). A systematic difference in the mean climate is found between the AGCM and the CGCM in the tropical Pacific. This difference is apparent when and where local SST is warmest. In the CGCM, precipitation does not last long due to SST and cloud-radiation feedback. Precipitation in the AGCM, however, tends to persist longer. Results of this experiment imply that caution is needed when using an AGCM with boundary conditions derived from a CGCM for climate change studies."
"7402483824;36892030100;","The diurnal cycle of west pacific deep convection and its relation to the spatial and temporal variation of tropical MCSs",1999,"10.1175/1520-0469(1999)056<3401:TDCOWP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033208544&doi=10.1175%2f1520-0469%281999%29056%3c3401%3aTDCOWP%3e2.0.CO%3b2&partnerID=40&md5=41570b146cde5182f739476b1ed802bb","Infrared (IR) and visible satellite data from the Japanese Geostationary Meteorological Satellite (GMS-4) with 5-km spatial and 1-h temporal resolution were used to examine the diurnal cycle of deep convection over a sector of the tropical west Pacific warm pool bounded by 0°-20°N, 140°E-180°. Data were analyzed for 45 days of summer from 22 June to 5 August 1994 and for 65 days of winter between 28 November 1994 and 31 January 1995. Deep convective clouds were identified in IR imagery using brightness temperature (TBB) threshold techniques. Based on previous studies, a -65°C cloud-top TBB threshold was chosen to isolate pixels containing active, deep convection. Spectral analysis of time series constructed from hourly cold cloud (£-65°C) pixel counts revealed a powerful diurnal cycle of deep convection significant at the 95% confidence level during summer and winter. Composited hourly statistics of fractional areal cloud cover documented a 0500-0600 local standard time (LST) maximum with a 1500-1900 LST minimum of convection for both seasons. Objective analysis techniques were developed to analyze the phase and amplitude of the diurnal cycle of deep convection and its relation to the satellite-observed daily spatial and temporal variation of tropical mesoscale convective systems (MCSs). Results showed that the diurnal cycle of convective rainfall with an early morning maximum was disproportionately dominated by the largest -10% of MCSs for each time period. While the number of large MCSs increased only slightly throughout nocturnal hours, the area of cold cloud associated with these systems expanded dramatically. An algorithm called ""threshold initiation"" showed that all scales of organized, intensifying deep convection existed at all times of day and night. In addition, the early morning peak was largely composed of building convection. Conditional recurrence probabilities of deep convection associated with MCSs were computed at 24- and 48-h intervals. Results for summer and December 1994 revealed that when early morning convection associated with a large MCS occurred at any location, the same region contained convection the next morning nearly half the time. Convection was less likely at the 48-h point. These results are not consistent with diurnal theories based on sea surface heating, afternoon initiation of convection, and nocturnal evolution of mesoscale convective systems. Findings indicate that the diurnal cycle of deep convective cloud is driven by the internal variation of large clusters. MCSs embedded in cloud clusters that exist into or form during the night grow spatially larger and more intense. Some results support direct radiative forcing of clouds and large-scale clear-region radiative destabilization as possible contributors to diurnal convective variability. However, all findings are consistent with the work of Gray and colleagues that emphasizes the role of day-night variations in net tropospheric cooling in clear and longwave cooling in cloudy versus clear regions as an explanation of the observed daily variation of tropical convective rainfall and its significant relationship to organized mesoscale convection. © 1999 American Meteorological Society."
"7403282069;7202208382;","A sensitivity study of radiative-convective equilibrium in the tropics with a convection-resolving model",1999,"10.1175/1520-0469(1999)056<3385:assorc>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033208554&doi=10.1175%2f1520-0469%281999%29056%3c3385%3aassorc%3e2.0.co%3b2&partnerID=40&md5=a701c4cc54da9ff272574286e1cca2a2","Statistical-equilibrium (SE) states of radiative-convective systems in tropical oceanic conditions are simulated with a cloud ensemble model (CEM) in this study. Typical large-scale conditions from the Marshall Islands and the eastern tropical Atlantic regions are used to drive the CEM. The simulated SE precipitable water, column temperature, and relative humidity are only slightly higher than those of the observed mean states in both regions when time-invariant large-scale total advective cooling and moistening effects are imposed from observations. They are much higher than the observed if time-invariant observed large-scale ascent is imposed for the Marshall Islands region (i.e., ignoring horizontal advective effects). Compared with results from two similar studies, this SE state is somewhere between the cold/dry regime by Sui et al. and the warm/humid regime by Grabowski et al. Temporal variations of the imposed large-scale vertical motion that allows for subsidence make the SE state colder and drier. It remains about the same, however, if the magnitude of the imposed large-scale vertical motion is halved. The SE state is also colder and drier if solar radiation is absent. In general, all the SE states show that wet columns are thermally more stable (unstable) and dry columns are thermally more unstable (stable) in the lower (upper) troposphere. Column budget analyses are performed to explore the differences among the simulations performed in this study and among the different studies. © 1999 American Meteorological Society."
"7102665209;6701679993;55401022300;7003931528;","Construction of a 1° x 1° fossil fuel emission data set for carbonaceous aerosol and implementation and radiative impact in the ECHAM4 model",1999,"10.1029/1999JD900187","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033610132&doi=10.1029%2f1999JD900187&partnerID=40&md5=db671e11152a3e1df052b3856b308001","Global-scale emissions of carbonaceous aerosol from fossil fuel usage have been calculated with a resolution of 1° x 1°. Emission factors for black and organic carbon have been gathered from the literature and applied to domestic, transport, and industrial combustion of various fuel types. In addition, allowance has been made for the level of development when calculating emissions from a country. Emissions have been calculated for 185 countries for the domestic, industrial, and transport sectors using a fuel usage database published by the United Nations [1993]. Some inconsistencies were found for a small number of countries with regard to the distribution of fuel usage between the industrial and domestic sectors. Care has been taken to correct for this using data from the fuel use database for the period 1970-1990. Emissions based on total particulate matter (TPM) and submicron emission factors have been calculated. Global emissions for 1984 of black carbon total 6.4 TgC yr-1 and organic carbon emissions of 10.1 TgC yr-1 were found using bulk aerosol emission factors, while global black carbon emissions of 5.1 TgC yr-1 and organic carbon emissions of 7.0 TgC yr-1 were found using submicron emission factors. Use of the database is quite flexible and can be easily updated as emission factor data are updated. There is at least a factor of 2 uncertainty in the derived emissions due to the lack of exactly appropriate emission data. The emission fields have been introduced into the ECHAM4 atmospheric general circulation model and run for 5 model years. Monthly mean model results are compared to measurements in regions influenced by anthropogenic fossil fuel emissions. The resultant aerosol fields have been used to calculate the instantaneous solar radiative forcing at the top of the troposphere due to an external mixture of fossil fuel derived black carbon and organic carbon aerosol. Column burdens of 0.143 mgBC m-2 and 0.170 mgOC m-2 were calculated. Because of secondary production of organic carbon aerosol, it is recommended that the burden of organic carbon aerosol be doubled to 0.341 mgOC m-2. The resultant forcing when clouds are included is +0.173 W m-2 for black carbon and -0.024 W m-2 for organic carbon (x2) as a global annual average. The results are compared to previous works, and the differences are discussed. Copyright 1999 by the American Geophysical Union."
"7004215973;57202521210;7004938676;7005135192;","Soot and sulfate aerosol particles in the remote marine troposphere",1999,"10.1029/1999JD900208","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033388516&doi=10.1029%2f1999JD900208&partnerID=40&md5=a7a39f3a3bd46ba99303451df7f6ad82","Sulfate aerosol particles containing soot aggregates were observed in the marine troposphere in both hemispheres under conditions that ranged from extremely clean to heavily polluted. Even in clean air above the remote Southern Ocean during the First Aerosol Characterization Experiment (ACE 1), depending on the sample, between 10 and 45% of sulfate particles contained soot inclusions. We identified aircraft emissions and biomass burning as the most likely major sources of soot. Internally mixed soot and sulfate appear to comprise a globally significant fraction of aerosols in the troposphere. Anthropogenic combustion aerosols can thus potentially change the radiative climate effects of sulfate aerosols and may have an impact on cloud properties even in the remote troposphere. Copyright 1999 by the American Geophysical Union."
"6602386862;7006452341;6602984400;","Climatic trends and interdecadal variability from South-Central Pacific coral records",1999,"10.1029/1999GL900595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033568901&doi=10.1029%2f1999GL900595&partnerID=40&md5=cdf1c8221156c8409a28f0d3aa5576bf","We study climate variability over interdecadal time scales from δ13C and δ18O records, measured in a Parites lutea coral core drilled in the Moorea lagoon. Previously, we demonstrated that the annual δ18O variations reflect those in sea-surface temperature (SST), while the annual δ13C variations record primarily cloud-cover changes. We apply two distinct spectral analysis methods to the δ13C and δ18O time series from 1853 to 1989. Our analysis of the δ18O record shows a secular warming trend and a 35-year oscillation in temperatures over the last 137 years. A trend and a 34-year cycle are also found in the δ13C record. The latter trend may be caused by either anthropogenic effects or a cloud-cover increase in this region of the Pacific Ocean, while the interdecadal oscillation appears to be related to changes in cloud cover, as well as in precipitation. Copyright 1999 by the American Geophysical Union."
"7004160106;7402390191;","Microphysics of Clouds with the Relaxed Arakawa-Schubert Scheme (McRAS). Part II: Implementation and performance in GEOS II GCM",1999,"10.1175/1520-0469(1999)056<3221:MOCWTR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033567647&doi=10.1175%2f1520-0469%281999%29056%3c3221%3aMOCWTR%3e2.0.CO%3b2&partnerID=40&md5=48059a24799dc362ec929a895a8d4081","A prognostic cloud scheme named the Microphysics of Clouds with the Relaxed Arakawa-Schubert Scheme (McRAS) and the Simple Biosphere Model have been implemented in a version of the Goddard Earth Observing System (GEOS) II GCM at a 4°latitude X 5°longitude X 20 sigma-layer resolution. The McRAS GCM was integrated for 50 months. The integration was initialized with the European Centre for Medium-Range Weather Forecasts analysis of observations for 1 January 1987 and was forced with the observed sea surface temperatures and sea-ice distribution; on land, the permanent ice and vegetation properties (biomes and soils) were climatological, while the soil moisture and snow cover were prognostic. The simulation shows that the McRAS GCM yields realistic structures of in-cloud water and ice, and cloud-radiative forcing (CRF) even though the cloudiness has some discernible systematic errors. The simulated intertropical convergence zone (ITCZ) has a realistic time mean structure and seasonal cycle. The simulated CRF is sensitive to vertical distribution of cloud water, which can be affected hugely with the choice of minimum in-cloud water for the onset of autoconversion or critical cloud water amount that regulates the autoconversion itself. The generation of prognostic cloud water is accompanied by reduced global precipitation and interactive CRF. These feedbacks have a profound effect on the ITCZ. Even though somewhat weaker than observed, the McRAS GCM simulation produces robust 30-60-day oscillations in the 200-hPa velocity potential. Comparisons of CRFs and precipitation produced in a parallel simulation with the GEOS II GCM are included. Several seasonal simulations were performed with the McRAS-GEOS II GCM for the summer (June-July-August) and winter (December-January-February) periods to determine how the simulated clouds and CRFs would be affected by (i) advection of clouds, (ii) cloud-top entrainment instability, (iii) cloud water inhomogeneity correction, and (iv) cloud production and dissipation in different cloud processes. The results show that each of these processes contributes to the simulated cloud fraction and CRF. Because inclusion of these processes helps to improve the simulated CRF, it is inferred that they would be useful to include in other cloud microphysics schemes as well. Two ensembles of four summer (July-August-September) simulations, one each for 1987 and 1988, were produced with the earlier 17-layer GEOS I GCM with McRAS. The differences show that the model simulates realistic and statistically significant precipitation differences over India, Central America, and tropical Africa. These findings were also confirmed in the new 20-layer GEOS II GCM with McRAS in the 1987 minus 1988 differences.The microphysics of clouds with the relaxed Arakawa-Schubert scheme (McRAS) and the simple biosphere model have been implemented in the Goddard Earth Observing System II general circulation model (GCM) at 4° latitude×5° longitude×20 sigma-layer resolution. The simulation show that the McRAS GCM yields realistic structures of in-cloud water and ice, and cloud-radiative forcing (CRF) eventhough the cloudiness has done discernible systematic errors. The simulated intertropical convergence zone has a realistic time mean structure and seasonal cycle. The simulated CRF is sensitive to vertical distribution of cloud water, which can be affected hugely with the choice of minimum in-cloud water for the onset of autoconversion or critical cloud water."
"7004369046;7202741460;7407016988;","Large-scale heat and moisture budgets over the ASTEX region",1999,"10.1175/1520-0469(1999)056<3241:LSHAMB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033567563&doi=10.1175%2f1520-0469%281999%29056%3c3241%3aLSHAMB%3e2.0.CO%3b2&partnerID=40&md5=aee4d5aa6ddf8046b38d879b28c8eaf1","Rawinsonde data collected from the Atlantic Stratocumulus Transition Experiment (ASTEX) were used to investigate the mean and temporal characteristics of large-scale heat and moisture budgets for a 2-week period in June 1992. During this period a large apparent heat sink and an apparent moisture source were observed near inversion base. Analyses from other budget studies show that similar convective signatures occur in a wide variety of regimes when trade wind-type inversions are present. In the lowest kilometer the vertical eddy flux of moist static energy over the ASTEX domain (centered at 33°N with an average sea surface temperature of 19.4°C) is about 60% of that observed in the undisturbed trade wind regime of BOMEX (centered at 15°N with an average sea surface temperature of 28.1°C). The apparent heat source, apparent moisture sink, and convective flux of moist static energy over ASTEX were strongly modulated on a synoptic timescale by the passage of fronts and by fluctuations in the subsidence rate associated with changes in the strength and position of the subtropical high. The influence of midlatitude disturbances on convection over ASTEX further distinguishes this region from the trade wind and tropical regimes. Daily budgets are examined for three different convective regimes during ASTEX to determine the mechanisms contributing to the large synoptic variability over this region.Rawinsonde data collected from the Atlantic Stratocumulus Transition Experiment (ASTEX) were used to investigate the mean and temporal characteristics of large-scale heat and moisture budgets for a 2-week period in June 1992. During this period a large apparent heat sink and an apparent moisture source were observed near inversion base. Analyses from other budget studies show that similar convective signatures occur in a wide variety of regimes when trade wind-type inversions are present. In the lowest kilometer the vertical eddy flux of moist static energy over the ASTEX domain (centered at 33°N with an average sea surface temperature of 19.4 °C) is about 60% of that observed in the undisturbed trade wind regime of BOMEX (centered at 15°N with an average sea surface temperature of 28.1 °C). The apparent heat source, apparent moisture sink, and convective flux of moist static energy over ASTEX were strongly modulated on a synoptic timescale by the passage of fronts and by fluctuations in the subsidence rate associated with changes in the strength and position of the subtropical high. The influence of midlatitude disturbances on convection over ASTEX further distinguishes this region from the trade wind and tropical regimes. Daily budgets are examined for three different convective regimes during ASTEX to determine the mechanisms contributing to the large synoptic variability over this region."
"57201725986;7006329926;7401559815;7201844203;","Large-scale forcing and cloud-radiation interaction in the tropical deep convective regime",1999,"10.1175/1520-0469(1999)056<3028:LSFACR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033395171&doi=10.1175%2f1520-0469%281999%29056%3c3028%3aLSFACR%3e2.0.CO%3b2&partnerID=40&md5=6fe4fd464d93fc7327f983e9750daca2","The simulations of tropical convection and thermodynamic states in response to different imposed large-scale forcing are carried out by using a cloud-resolving model and are evaluated with the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment observation. The model is forced either with imposed large-scale vertical velocity and horizontal temperature and moisture advections (model 1) or with imposed total temperature and moisture advections (model 2). The comparison of simulations with observations shows that bias in temperature and moisture simulations by model 1 is smaller than that by model 2. This indicates that the adjustment of the mean thermodynamic stability distribution by vertical advection in model 1 is responsible for better simulations. Model 1 is used to examine effects of different parameterized solar radiative and cloud microphysical processes. A revised parameterization scheme for cloud single scattering properties in solar radiation calculations is found to generate more solar heating in the upper troposphere and less heating in the middle and lower troposphere. The change in the vertical heating distribution is suggested to stabilize the environment and to cause less stratiform cloud that further induces stabilization through cloud-IR interaction. The revised scheme also causes a drier middle and lower troposphere by weakening vertical moisture flux convergence. Also tested is the effect of a revised parameterization scheme for cloud microphysical processes that tends to generate more ice clouds. The cloud-induced thermal effect in which less ice cloud leads to less infrared cooling at cloud top and more heating below cloud top is similar to the effect of no cloud-radiation interaction shown in a sensitivity experiment. However, the exclusion of cloud-radiation interaction causes drying by enhancing condensation, and the reduction of ice clouds by the microphysics scheme induces moistening by suppressing condensation.The simulations of tropical convection and thermodynamic states in response to different imposed large-scale forcing are carried out by using a cloud-resolving model and are evaluated with the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment observation. The model is forced either with imposed large-scale vertical velocity and horizontal temperature and moisture advections (model 1) or with imposed total temperature and moisture advections (model 2). The comparison of simulations with observations shows that bias in temperature and moisture simulations by model 1 is smaller than that by model 2. This indicates that the adjustment of the mean thermodynamic stability distribution by vertical advection in model 1 is responsible for better simulations. Model 1 is used to examine effects of different parameterized solar radiative and could microphysical processes. A revised parameterization scheme for cloud single scattering properties in solar radiation calculations is found to generate more solar heating in the upper troposphere and less heating in the middle and lower troposphere. The change in the vertical heating distribution is suggested to stabilize the environment and to cause less stratiform cloud that further induces stabilization through cloud-IR interaction. The revised scheme also causes a drier middle and lower troposphere by weakening vertical moisture flux convergence. Also tested is the effect of a revised parameterization scheme for cloud microphysical processes that tends to generate more ice clouds. The cloud-induced thermal effect in which less ice cloud leads to less infrared cooling at cloud top and more heating below cloud top is similar to the effect of no cloud-radiation interaction shown in a sensitivity experiment. However, the exclusion of cloud-radiation interaction causes drying by enhancing condensation, and the reduction of ice clouds by the microphysics scheme induces moistening by suppressing condensation."
"57199755749;7004423053;7005027192;7005902195;56618721800;7003395620;56617849900;7101728297;6602458968;","The substitution of high-resolution terrestrial biosphere models and carbon sequestration in response to changing CO2 and climate",1999,"10.1029/1999GB900035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033385509&doi=10.1029%2f1999GB900035&partnerID=40&md5=ea7c6545539286e0f031d17b6999d15a","Strategies are developed to analyze and represent spatially resolved biosphere models for carbon sequestration in response to changes in atmospheric CO2 and climate by reduced-form, substitute models. We explore the High-Resolution Terrestrial Biosphere Model as implemented in the Community Terrestrial Biosphere Model (HRBM/CTBM), the Frankfurt Biosphere Model (FBM), and the box-type biosphere of the Bern model. Storage by CO2 fertilization is described by combining analytical representations of (1) net primary productivity (NPP) as a function of atmospheric CO2 and (2) a decay impulse response function to characterize the timescales of biospheric carbon turnover. Storage in response to global warming is investigated for the HRBM/CTBM. The relation between the evolution of radiative forcing and climate change is expressed by a combination of impulse response functions and empirical orthogonal functions extracted from results of the European Center/Hamburg (ECHAM3) coupled atmosphere-ocean general circulation model. A box-type, differential-analogue substitute model is developed to represent global carbon storage of the HRBM/CTBM in response to regional changes in Temperature, Precepitation and cloud cover. The substitute models represent the spatially resolved models accurately and cost-efficiently for carbon sequestration in response to changes in CO2 or in CO2 and climate and for simulations of the global isotopic signals. Deviations in carbon uptake simulated by the spatially resolved models and their substitutes are less than a few percent."
"7202772927;35467186900;7006329926;6701681018;56283009900;7401559815;7006095466;","Equilibrium states simulated by cloud-resolving models",1999,"10.1175/1520-0469(1999)056<3128:ESSBCR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033375479&doi=10.1175%2f1520-0469%281999%29056%3c3128%3aESSBCR%3e2.0.CO%3b2&partnerID=40&md5=0596a3aa88f7fe6059a5f962851b9f94","Recently, several cloud-resolving models (CRMs) were used to study the tropical water and energy cycles and their role in the climate system. They are typically run for several weeks until modeled temperature and water vapor fields reach a quasi-equilibrium state. However, two CRMs produced different quasi-equilibrium states (warm and humid versus cold and dry) even though both used similar initial thermodynamic profiles, horizontal wind, prescribed large-scale vertical velocity, and fixed sea surface temperature. Sensitivity tests were designed to identify the major physical processes that determine the equilibrium states for the different CRM simulations. Differences in the CRM simulated quasi-equilibrium state can be attributed to how the atmospheric horizontal wind was treated throughout the integration. The model that had stronger surface wind produced a warmer and more humid thermodynamic equilibrium state. The physical processes responsible for determining the modeled equilibrium states can be identified by examining the differences in the modeled water vapor, temperature, and moist static energy budget between warm/humid and cold/dry states. One of the major physical processes responsible for the warmer and more humid equilibrium state is larger latent heat fluxes from the ocean (due to stronger surface wind). The moist static energy budget further indicates that the large-scale forcing in water vapor is another major physical process responsible for producing the warmer and more humid thermodynamic equilibrium state. The model results also indicated that the advective forcing in temperature (cooling) and water vapor (moistening) by the imposed large-scale vertical velocity was larger (smaller) for the warm and humid (cold and dry) equilibrium state. This is because the domain mean thermodynamic state is more unstable and has a stronger vertical gradient of water vapor for those experiments that produced a warmer and more humid climate. Specified minimum wind speed in the bulk aerodynamic formulas and initial soundings on the modeled thermodynamic equilibrium state are also discussed.Recently, several cloud-resolving models (CRMs) were used to study the tropical water and energy cycles and their role in the climate system. They are typically run for several weeks until modeled temperature and water vapor fields reach a quasi-equilibrium state. However, two CRMs produced different quasi-equilibrium states (warm and humid versus cold and dry) even though both used similar initial thermodynamic profiles, horizontal wind, prescribed large-scale vertical velocity, and fixed sea surface temperature. Sensitivity tests were designed to identify the major physical processes that determine the equilibrium states for the different CRM simulations. Differences in the CRM simulated quasi-equilibrium state can be attributed to how the atmospheric horizontal wind was treated throughout the integration. The model that had stronger surface wind produced a warmer and more humid thermodynamic equilibrium state. The physical processes responsible for determining the modeled equilibrium states can be identified by examining the differences in the modeled water vapor, temperature, and moist static energy budget between warm/humid and cold/dry states. One of the major physical processes responsible for the warmer and more humid equilibrium state is larger latent heat fluxes from the ocean (due to stronger surface wind). The moist static energy budget further indicates that the large-scale forcing in water vapor is another major physical process responsible for producing the warmer and more humid thermodynamic equilibrium state. The model results also indicated that the advective forcing in temperature (cooling) and water vapor (moistening) by the imposed large-scale vertical velocity was larger (smaller) for the warm and humid (cold and dry) equilibrium state. This is because the domain mean thermodynamic state is more unstable and has a stronger vertical gradient of water vapor for those experiments that produced a warmer and more humid climate. Specified minimum wind speed in the bulk aerodynamic formulas and initial soundings on the modeled thermodynamic equilibrium state are also discussed."
"35612340000;7006114701;7003346072;","MODIS vegetation index compositing approach: A prototype with AVHRR data",1999,"10.1016/S0034-4257(99)00022-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033199148&doi=10.1016%2fS0034-4257%2899%2900022-X&partnerID=40&md5=092206819be4b8a73e5bd70b8685e506","In this study, the 16-day MODIS (MODerate resolution Imaging Spectroradiometer) vegetation index (VI) compositing algorithm and product were described, evaluated, and compared with the current AVHRR (Advanced Very High Resolution Spectroradiometer) maximum value composite (MVC) approach. The MVC method selects the highest NDVI (normalized difference vegetation index) over a certain time interval. The MODIS VI compositing algorithm emphasizes a global and operational view angle standardization approach: a reflectance-based BRDF (Bidirectional Reflectance Distribution Function) model, succeeded by a back-up MVC algorithm that includes a view angle constraint. A year's worth of daily global AVHRR data was used to prototype the MODIS vegetation index compositing algorithm. The composite scenarios were evaluated with respect to: 1) temporal evolution of the VI for different continents and vegetation types, 2) spatial continuity of the VI, 3) quality flags related to data integrity, cloud cover, and composite method, and 4) view angle distribution of the composited data. On a continental scale, the composited NDVI values from the MODIS algorithm were as much as 30% lower than the mostly, off-nadir NDVI results based on the MVC criterion. The temporal evolution of the NDVI values derived with the MODIS algorithm were similar to the NDVI values derived from the MVC algorithm. A simple BRDF model was adequate to produce nadir equivalent reflectance values from which the NDVI could be computed. Application of the BRDF and 'back-up' components in the MODIS algorithm were dependent on geographic location and season, for example, the BRDF interpolation was most frequently applied in arid and semiarid regions, and during the dry season over humid climate vegetation types. Examples of a MODIS-like global NDVI map and associated quality flags were displayed using a pseudo color bit mapping scheme.In this study, the 16-day MODIS (MODerate resolution Imaging Spectroradiometer) vegetation index (VI) compositing algorithm and product were described, evaluated, and compared with the current AVHRR (Advanced Very High Resolution Spectroradiometer) maximum value composite (MVC) approach. The MVC method selects the highest NDVI (normalized difference vegetation index) over a certain time interval. The MODIS VI compositing algorithm emphasizes a global and operational view angle standardization approach: a reflectance-based BRDF (Bidirectional Reflectance Distribution Function) model, succeeded by a back-up MVC algorithm that includes a view angle constraint. A year's worth of daily global AVHRR data was used to prototype the MODIS vegetation index compositing algorithm. The composite scenarios were evaluated with respect to: 1) temporal evolution of the VI for different continents and vegetation types, 2) spatial continuity of the VI, 3) quality flags related to data integrity, cloud cover, and composite method, and 4) view angle distribution of the composited data. On a continental scale, the composited NDVI values from the MODIS algorithm were as much as 30% lower than the mostly, off-nadir NDVI results based on the MVC criterion. The temporal evolution of the NDVI values derived with the MODIS algorithm were similar to the NDVI values derived from the MVC algorithm. A simple BRDF model was adequate to produce nadir equivalent reflectance values from which the NDVI could be computed. Application of the BRDF and `back-up' components in the MODIS algorithm were dependent on geographic location and season, for example, the BRDF interpolation was most frequently applied in arid and semiarid regions, and during the dry season over humid climate vegetation types. Examples of a MODIS-like global NDVI map and associated quality flags were displayed using a pseudo color bit mapping scheme."
"55660987600;","Coral decline and weather patterns over 20 years in the Chagos Archipelago, central Indian Ocean",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032725189&partnerID=40&md5=cd2354dd8342065517fe663570a83efc","The atolls of the Chagos Archipelago occupy a key location in the central Indian Ocean, in biogeographical terms. They are remote and largely uninhabited, and its reefs have almost completely escaped most forms of direct human impact. Despite this, there has been a marked decline in their coral cover over the last 20 years. In particular, live coral cover fell markedly following the warm sea-water episode of 1998, such that on seaward reefs of all six Chagos atolls, only 12% of the substrate is now living coral compared with 50-75% before the warming event. On seaward reefs, 40% of the substrate is now covered by dead coral, and another 40% by unidentifiable dead coral and bare substrate. Lagoonal reefs fared better than seaward reefs, but still lost half of their corals over the last year. All reefs now have large quantities of mobile, dead coral fragments which may inhibit new recruitment and growth. Weather data have been recorded in Chagos since 1973. Statistically significant trends include a 1°C rise in mean air temperature over 25 years, and a 2°C rise in the warmest 95 percentile temperature. At the same time there has been a fall in mean annual pressure, a reduction in cloud cover, and winds have become more variable. Fourier analysis of temperature data shows several cycles of 2 years or longer, which when combined indicate a greater climate variability today compared with 25 years ago. Periods of higher temperatures coincide with several previous El Nino events and other climatic records of warming. Although the latest warming of 1998 is responsible for the recent mass coral mortality, it is seen to be a severe continuation of a longer trend, which if continued leads to a poor prognosis for rapid recovery."
"7005246513;7004027377;7005399437;7005793702;7004467879;","Assessment of smoke aerosol impact on surface solar irradiance measured in the Rondônia region of Brazil during Smoke, Clouds, and Radiation - Brazil",1999,"10.1029/1999JD900258","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033609591&doi=10.1029%2f1999JD900258&partnerID=40&md5=d2cfecdffe911bcb01eeb22509463de2","The impact of smoke aerosols on the surface solar irradiance in the Rondônia region of Brazil is examined. The climate of this region is subequatorial with two distinct seasons. There is a sharp decline of the precipitation and cloudiness during the dry season which lasts from June to September accompanied by anthropogenic burning of savanna and forest in August and September with the resultant strong emission of smoke into the troposphere. Thus the magnitude of the column aerosol optical depth increases in these months while both precipitable water and cloud amount decrease in accordance with the seasonal cycle of humidity. All these atmospheric constituents influence the magnitude of the solar irradiance at the surface. In order to assess the aerosol and gaseous effects on the surface irradiance as compared with impact of cloudiness, we performed the clear-sky radiative transfer model calculations by employing a broadband radiation code and both aerosol optical depth and precipitable water retrieved from Sun photometer measurements. Calculation results show that the elevated aerosol optical depth observed in Rondônia during August and September causes a negative trend in the daily mean clear-sky surface solar irradiance during this period. Since the daily mean solar irradiance measured at the surface under all-sky conditions demonstrates a similar negative trend, it can be explained by the aerosol influence while the effect of clouds appears in the daily variations of the irradiance. It was also shown that smoke aerosols cause a decrease of the monthly mean values of all-sky surface irradiance in August and September as compared with July and October. Corresponding decreases in the near surface air temperature due to the smoke aerosols were not found. Copyright 1999 by the American Geophysical Union."
"56236744600;7102900959;","Inference of snow cover beneath obscuring clouds using optical remote sensing and a distributed snow energy and mass balance model",1999,"10.1029/1999JD900249","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0007153473&doi=10.1029%2f1999JD900249&partnerID=40&md5=1d733469f7fcbd8164c1fdae0ba335e3","We describe a new method to infer the presence or absence of snow cover when it is obscured to remote sensing by clouds. The inference is based on the spatial distribution of snow water equivalent (SWE) estimated by a physical snow model. The snow model accounts for surface and internal snowpack energy exchanges and mass exchanges including snow accumulation, sublimation, rainfall, and meltwater outflux. We examine two approaches to using the modeled SWE information to infer snow cover: (1) we directly categorize areas with modeled SWE greater than zero as ""snow covered"" and areas with zero SWE as ""no snow""; (2) we classify the modeled SWE field into a binary map of snow covered/no snow, using maximum likelihood logistic estimation (LR). Here the modeled SWE serves as a semicontinuous independent variable, and the binary dependent variable consists of observed snow cover derived from all available ground observations of snow depth and water equivalent, and from samples of snow cover randomly selected from cloud-free areas of a satellite snow cover product. We demonstrate these methods for a 504,000 km2 region in the north central United States, over a 4 week period during March and April 1997. The snow model was run hourly on a 4 km grid using data normally available in near real time, including numerical weather analysis products, satellite-derived insolation products, and ground observations of precipitation. We tested two dependent variable data configurations for the LR approach to simulate (1) typical conditions when remotely sensed snow cover observations are available to help develop the logistic model and (2) ""worst-case"" conditions where only ground-based data are available. Averaged over the study period, all three methods, the direct SWE, the worst-case LR, and the typical LR, yielded comparable results in the range of 78-80% accuracy when compared to satellite-observed snow cover maps. The results of this study demonstrate that a relatively simple, spatially distributed, physically based snow model is capable of providing useful snow cover information in an operational environment."
"6701358470;7202163945;7201771183;7202612588;57190613121;6603699729;36801353600;","Assessment of land-surface energy budgets from regional and global models",1999,"10.1029/1999JD900128","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033609585&doi=10.1029%2f1999JD900128&partnerID=40&md5=a040d60864f4e9d21c4eeaf7462c60a4","The surface energy budgets estimated from the 0- to 12-hour forecasts of three operational model suites and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis are analyzed at local to continental scales. The models are (1) the Eta model, (2) the Mesoscale Analysis and Prediction System (MAPS), and (3) the Global Environmental Multiscale (GEM) model. The first two are regional, while the third one is global with a variable grid with a resolution over North America that is equivalent to that of the regional models. This assessment of one summer month (August 1997) and one winter month (January 1998) has the purpose of estimating the reliability of the surface energy budgets within the context of the Global Energy and Water Cycle Experiment (GEWEX) Continental-Scale International Project (GCIP) goals. Satellite estimates were used to evaluate the downward short wave radiation at the surface, while measurements from the southern Great Plains region were used to evaluate the model computed surface energy budget estimates. The results show that the surface short wave radiation biases of the models are widespread and of the order of 25-50 W m-2 and averaging over larger areas does not help reduce the differences. These biases are compensated by the other long and short wave radiation terms so that the resulting errors in the net radiation are smaller. During August 1997, continental east-west gradients of latent heat flux and Bowen ratio were surprisingly dissimilar among models. Still, the Bowen ratio estimated from the Eta and GEM models was close to observations over the southern Great Plains region, while both the Reanalysis and MAPS had ratios that at least doubled the observed ones. In the case of MAPS a revised latent heat flux formulation was introduced in fall 1997, and, subsequently, for January 1998, estimates were closer to the other models' estimates. However, during January 1998 all models had difficulties reproducing the Bowen ratios from observations. Further, daily time series showed that models' estimates also tended to miss the amplitude of the day-to-day variability. It is conceivable that this may be the result of difficulties in parameterizing the total cloud cover, and, particularly, attenuation by clouds may still be insufficient. Copyright 1999 by the American Geophysical Union."
"57201201895;7201646465;56853406500;","Toward a parameterization of mesoscale fluxes and moist convection induced by landscape heterogeneity",1999,"10.1029/1999JD900361","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033609635&doi=10.1029%2f1999JD900361&partnerID=40&md5=09fc50bba2283fb5f47f39e98e3030f6","A growing body of evidence from modeling and observations indicates that mesoscale circulations generated by land-surface wetness heterogeneities result in substantial vertical fluxes of sensible heat and moisture. These fluxes are believed to have a strong impact on large-scale mean atmospheric variables such as temperature, humidity, cloudiness, and precipitation. Currently, however, this type of mesoscale convective process is not considered in general circulation models (GCMs). In this study, we develop a parameterization for these landscape-forced fluxes, similar to what might eventually be implemented into a GCM. In addition, we investigate the relationship between the parameterized mesoscale flux and the convective condensation associated with these circulations as a first step toward directly including clouds and precipitation forced by surface heterogeneity effects as one component of a comprehensive GCM convective scheme. To generate the data necessary for this development, we perform a number of simulations with a state-of-the-art mesoscale model to determine the sensitivity of the fluxes and condensation to a variety of background atmospheric conditions and land-surface wetness distributions. We use similarity theory to determine the dependence of the mesoscale sensible heat and moisture fluxes on the parameters relevant to the problem, and we create parameterized vertical flux profiles by fitting with Chebyshev polynomials. The parameterized fluxes are tested against an independent, three-dimensional (3-D) simulation of mesoscale development over a heterogeneous landscape, and general good agreement is found. We propose an empirical form for domain-averaged condensation on the basis of a linear relationship with parameterized mesoscale moisture flux and also demonstrate a reasonable agreement with the results from the 3-D simulation. The methodology of this study, i.e., the use of a numerical model in the preliminary stages of parameterization development, is advantageous for situations where the necessary observational data set is nonexistent. The use of model simulations to fully explore the parameter space of this type of problem should then lead to observational campaigns that focus on only those key processes and variables which are relevant for the further refinement of a given parameterization. Copyright 1999 by the American Geophysical Union."
"6701481405;7007162531;6507173708;8108550400;","Accounting for clouds in sea ice models",1999,"10.1016/S0169-8095(99)00028-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033429055&doi=10.1016%2fS0169-8095%2899%2900028-9&partnerID=40&md5=2848e41ecbbffb57a68ea2e8fef54ce6","Over sea ice in winter, the clouds, the surface-layer air temperature, and the long-wave radiation are closely coupled. Here we use archived data from the Russian North Pole (NP) drifting stations and our own data from Ice Station Weddell (ISW) to investigate this coupling. Both Arctic and Antarctic distributions of total cloud amount are U-shaped: that is, observed cloud amounts are typically either 0-2 tenths or 8-10 tenths in the polar regions. We fitted these data with beta distributions and, using roughly 70 station-years of observations from the NP stations, compute fitting parameters for each winter month. Although we find that surface-layer air temperature and total cloud amount are correlated, it is not straightforward to predict one from the other because temperature is normally distributed while cloud amount has a U-shaped distribution. Nevertheless, we develop a statistical algorithm that can predict total cloud amount in winter from surface-layer temperature alone and, as required, produces a distribution of cloud amounts that is U-shaped. Because sea ice models usually need cloud data to estimate incoming long-wave radiation, this algorithm may be useful for estimating cloud amounts and, thus, for computing the surface heat budget where no visual cloud observations are available but temperature is measured - from the Arctic buoy network or from automatic weather stations, for example. The incoming long-wave radiation in sea ice models is generally highly parameterized. We evaluate five common parameterizations using data from NP-4, NP-25, and ISW. The formula for estimating incoming long-wave radiation that Konig-Langlo and Augstein developed using both Arctic and Antarctic data has the best properties but does depend nonlinearly on total cloud amount. This nonlinearity is crucial since cloud distributions are U-shaped while common sources of cloud data tabulate only mean monthly values. Lastly, we therefore use a one-dimensional sea ice model to investigate how methods of averaging cloud amounts affect predicted sea ice thickness in the context of the five long-wave radiation parameterizations. Here, too, Konig-Langlo and Augstein's formula performs best, and using daily averaged cloud data yields more realistic results than using monthly averaged cloud data that have been interpolated to daily values."
"7005650812;","Cloud-induced infrared radiative heating and its implications for large-scale tropical circulations",1999,"10.1175/1520-0469(1999)056<2657:CIIRHA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032763837&doi=10.1175%2f1520-0469%281999%29056%3c2657%3aCIIRHA%3e2.0.CO%3b2&partnerID=40&md5=82e1085dce40305729aca4cf8d481743","Three-dimensional global distributions of longwave radiative cooling for the summer of 1988 and the winter of 1989 are generated from radiative transfer calculations using European Centre for Medium-Range Weather Forecasts temperature and humidity profiles and International Satellite Cloud Climatology Project cloudiness as inputs. By adding the cooling of the clear atmosphere to the total radiative heating, cloud-induced atmospheric radiative heating has been obtained. Emphasis is placed on the impact of horizontal gradients of the cloud-generated radiative heating on the global atmospheric circulation. Cloud-induced heating, whose general pattern is well in agreement with total diabatic heating suggested by other studies, exhibits its maximum heating areas within the Indian Ocean and the western Pacific. By contrast, maximum cooling areas are found in the northern and southern flanks of the Indian Ocean, and over the eastern Pacific off the west coasts of both North and South America. The fact that these heating and cooling distributions reinforce the climatologically favored heating gradients both in the meridional and zonal directions indicates that cloud-radiative feedback can enhance the strength of both the north-south Hadley circulation and the east-west Walker circulation.Three-dimensional global distributions of longwave radiative cooling for the summer of 1988 and the winter of 1989 are generated from radiative transfer calculations using European Centre for Medium-Range Weather Forecasts temperature and humidity profiles and International Satellite Cloud Climatology Project cloudiness as inputs. By adding the cooling of the clear atmosphere to the total radiative heating, cloud-induced atmospheric radiative heating has been obtained. Emphasis is placed on the impact of horizontal gradients of the cloud-generated radiative heating on the global atmospheric circulation. Cloud-induced heating, whose general pattern is well in agreement with total diabetic heating suggested by other studies, exhibits its maximum heating areas within the Indian Ocean and the western Pacific. By contrast, maximum cooling areas are found in the northern and southern flanks of the Indian Ocean, and over the eastern Pacific off the west coasts of both North and South America. The fact that these heating and cooling distributions reinforce the climatologically favored heating gradients both in the meridional and zonal directions indicates that cloud-radiative feedback can enhance the strength of both the north-south Hadley circulation and the east-west Walker circulation."
"7004556087;35477504600;6602238735;7801611054;56222822400;7801333278;57196815324;6504579471;7005893321;","Contribution of carbonaceous material to cloud condensation nuclei concentrations in European background (Mt. Sonnblick) and urban (Vienna) aerosols",1999,"10.1016/S1352-2310(98)00391-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033180893&doi=10.1016%2fS1352-2310%2898%2900391-4&partnerID=40&md5=ed298fe311e60c713f55f438ddffd8d5","During four intensive measurement campaigns (two on Mt. Sonnblick, European background aerosol, and two in Vienna, urban aerosol), cloud condensation nuclei (CCN) were measured at supersaturations of 0.5%. Impactor measurements of the mass size distribution in the size range 0.1-10 μm were performed and later analyzed for Cl-, NO3/-, SO4/2-, Na+, NH4/+, K+, Ca2+ and Mg2+ by ion chromatography, for total carbon (TC) using a combustion method, and for black carbon (BC) by an optical method (integrating sphere). Organic carbon (OC) was defined as the difference between TC (minus carbonate carbon) and BC. At all sites, the mass fraction of BC in the submicron aerosol was comparable (4-5%). CCN concentrations on Mt. Sonnblick were found tO be 10-30% of those measured in Vienna, although high Mt. Sonnblick concentrations were comparable to low Vienna concentrations (around 800 cm-3). The contribution of organic material was estimated from the mass concentrations of the chemical species sampled on the impactor stage with the lowest cut point (0.1-0.215 μm aerodynamic equivalent diameter). Oh Mt. Sonnblick, TC material contributed 11% to the total mass in fall 1995, and 67% in summer 1996, while the OC fraction was 6 and 61%. The combined electrolytes and mineral material contributed 18 and 16% in fall and summer. During the Vienna spring campaign, the contributions of OC and electrolytes to the total mass concentration in this size range were 48 and 36%, respectively."
"12139310900;56250250300;","A scheme for black carbon and sulphate aerosols tested in a hemispheric scale, Eulerian dispersion model",1999,"10.1016/S1352-2310(98)00389-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033180863&doi=10.1016%2fS1352-2310%2898%2900389-6&partnerID=40&md5=451d8f6dee2e3a565354bc3148616e24","Production, transport and deposition of sulphate and black carbon (BC) are simulated separating aerosol modes by production mechanisms, thus facilitating calculation of aerosol physical properties. The scheme uses explicit sulphur chemistry with prescribed oxidants and aerosol transformation based on Brownian coagulation rates, and is implemented in a 3-D, hemispheric-scale transport model with off-line meteorology from ECMWF. The components are DMS, SO2, sulphate and BC. Simulations are made for the year 1988. Predicted results for sulphate agree well with the measurements, except for considerable underestimations in the Arctic. In Europe SO2 is slightly overestimated and sulphate is slightly underestimated in cold seasons, whilst trends are less clear in North America. Compared to many other models, we estimate a smaller effective oxidation rate for SO2 due to reduced rates in cold clouds; a shorter turnover time for sulphate (3.7 d) due to a probably too large below-cloud scavenging ratio; and slightly smaller sulphate column burdens. Our BC results are similar to Liousse et al.'s (1996, J. Geophys. Res. 101, 19.411-19.432) except in USA, whilst the concentrations in remote areas and the turnover time (3.7 d) are considerably smaller than Cooke and Wilson's (1996, J. Geophys. Res. 101, 190.395-19.409). Agreements with available measurements are quite close to large anthropogenic emissions (including USA), but they are considerably underestimated in Arctic winter. Transition from hydrophobic to hydrophilic BC due to coagulation is swift (6% h-1). Sensitivity tests emphasize that sub-cloud scavenging coefficients rely on careful assumptions about size distributions, and that more research is needed on sulphate production in ice-clouds. Emphasis should also be put on production of sulphate and hydrophilic BC boundary-layer clouds; inclusion of hydrophobic accumulation mode BC and sub-grid transition to hydrophilic BC in emitting grid squares.Production, transport and deposition of sulphate and black carbon (BC) are simulated separating aerosol modes by production mechanisms, thus facilitating calculation of aerosol physical properties. The scheme uses explicit sulphur chemistry with prescribed oxidants and aerosol transformation based on Brownian coagulation rates, and is implemented in a 3-D, hemispheric-scale transport model with off-line meteorology from ECMWF. The components are DMS, SO2 sulphate and BC. Simulations are made for the year 1988. Predicted results for sulphate agree well with the measurements, except for considerable underestimations in the Arctic. In Europe SO2 is slightly overestimated and sulphate is slightly underestimated in cold seasons, whilst trends are less clear in North America. Compared to many other models, we estimate a smaller effective oxidation rate for SO2 due to reduced rates in cold clouds; a shorter turnover time for sulphate (3.7 d) due to a probably too large below-cloud scavenging ratio; and slightly smaller sulphate column burdens. Our BC results are similar to Liousse et al.'s (1996, J. Geophys. Res. 101, 19.411-19.432) except in USA, whilst the concentrations in remote areas and the turnover time (3.7 d) are considerably smaller than Cooke and Wilson's (1996, J. Geophys. Res. 101, 190.395-19.409). Agreements with available measurements are quite close to large anthropogenic emissions (including USA), but they are considerably underestimated in Arctic winter. Transition from hydrophobic to hydrophilic BC due to coagulation is swift (6% h-1). Sensitivity tests emphasize that sub-cloud scavenging coefficients rely on careful assumptions about size distributions, and that more research is needed on sulphate production in ice-clouds. Emphasis should also be put on production of sulphate and hydrophilic BC boundary-layer clouds; inclusion of hydrophobic accumulation mode BC and sub-grid transition to hydrophilic BC in emitting grid squares."
"7003848718;","Roll and cell convection in wintertime arctic cold-air outbreaks",1999,"10.1175/1520-0469(1999)056<2613:RACCIW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345201754&doi=10.1175%2f1520-0469%281999%29056%3c2613%3aRACCIW%3e2.0.CO%3b2&partnerID=40&md5=863cc27bfbd3b6e5a1d18418f07525ec","Cold-air outbreaks from the polar ice caps or winterly continents over the open ocean lead to organized convection that typically starts as longitudinal roll patterns and changes to cellular patterns in downstream direction. During the field experiments ARKTIS 1991 and ARKTIS 1993, aircraft missions were conducted in 13 cold-air outbreak events over the Greenland and Barents Seas to determine the characteristic parameters of both the mean (primary) flow and the superimposed organized convection (secondary flow). The measurements are classified into four categories with respect to the convective pattern form: longitudinal rolls with small and wider horizontal wavelengths, transitional forms between rolls and cells, and cells. Rolls were observed for boundary layer depths h &lt; 1 km with horizontal wavelengths λ &lt; 5 km and aspect ratios λ/h between 2.6 and 6.5. Distinct cellular structures occurred for h &gt; 1.4 km with λ &gt; 8 km and λ/h between 4 and 12. The amplitudes of the secondary flow-scale variations of the temperature θ(R), moisture m(R), and the longitudinal, u(R); transversal, v(R); and vertical, w(R), wind components were on the order of 0.1-0.4 K, 0.03-0.30 g kg-1, 0.6-2.5 m s-1, 0.8-2.5 m s-1, and 0.4-1.8 m s-1, respectively, generally increasing from the roll to the cell region. The same is true for the ratio u(R)/v(R) (from about 0.6 to nearly 1) and for the ratio Lm(R)/c(P)θ(R) (from 0.7 to more than 2), hinting at increasing importance of moisture processes in the cell compared to the roll region. The importance of the secondary-flow transports of heat and momentum in relation to the total vertical transports increases with height and from rolls to cells. Particularly clear is the vertical profile of the vertical moisture transport m(R)w(R), which exhibits a maximum around cloud base and is on the average related to the surface moisture flux as (m(R)w(R))(max) = 0.35(m'w')(o). The thermodynamic conditions of the basic flow are characterized by the Rayleigh number Ra, the stability of the capping inversion, and the net condensation rate in the cloud layer. Here Ra is clearly overcritical in the whole cold-air outbreak region; it is around 105 in the roll region and around 2 X 106 in the cell region. The Monin-Obukhov stability parameter does not appear to be suitable measure to distinguish between roll and cell convection. The stability above the boundary layer is about two to three times larger for rolls than for cells. The net condensation in clouds is three times larger in cell than in roll regions and the resulting heating of the boundary layer exceeds that of the surface heat flux in the cell region. The kinematic conditions of the basic flow are characterized by a larger shear of the longitudinal wind component u in the roll than in the cell region. The curvature of the u profile is mostly overcritical in rolls and always subcritical in cells. The secondary flow-scale kinetic energy E(kin,R) is related to Ra. The best least squares fit is given by E(kin,R) = 3.7Ra0.4.Cold-air outbreaks from the polar ice caps or winterly continents over the open ocean lead to organized convection that typically starts as longitudinal roll patterns and changes to cellular patterns in dowstream direction. This article discusses the ARKTIS 1991 and ARKTIS 1993 field experiments where aircraft missions were conducted in 13 cold-air outbreak events over the Greenland and Barents Seas to determine the characteristic parameters of both the mean flow and the superimposed organized convection. The measurements are classified into four categories with respect to the convective pattern form: longitudinal rolls with small and wider horizontal wavelengths, transitional forms between rolls and cells, and cells."
"57209089997;35453054300;7004670952;7401569549;7003657704;","Potential impacts on Colorado Rocky Mountain weather due to land use changes on the adjacent Great Plains",1999,"10.1029/1999JD900118","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033436307&doi=10.1029%2f1999JD900118&partnerID=40&md5=43fe3480ce6c46ace8710432933a12b0","Evidence from both meteorological stations and vegetational successional studies suggests that summer temperatures are decreasing in the mountain-plain system in northeast Colorado, particularly since the early 1980s. These trends are coincident with large changes in regional land cover. Trends in global, Northern Hemisphere and continental surface temperatures over the same period are insignificant. These observations suggest that changes in the climate of this mountain-plain system may be, in some part, a result of localized forcing mechanisms. In this study the effects of land use change on the northern Colorado plains, where large regions of grasslands have been transformed into both dry and irrigated agricultural lands, on regional weather is examined in an effort to understand this local deviation from larger-scale trends. We find with high-resolution numerical simulations of a 3-day summer period using a regional atmospheric-land surface model that replacing grasslands with irrigated and dry farmland can have impacts on regional weather and therefore climate which are not limited to regions of direct forcing. Higher elevations remote from regions of land use change are affected as well. Specifically, cases with altered landcover had cooler, moister boundary layers, and diminished low-level upslope winds over portions of the plains. At higher elevations, temperatures also were lower as was low-level convergence. Precipitation and cloud cover were substantially affected in mountain regions. We advance the hypothesis that observed land use changes may have already had a role in explaining part of the observed climate record in the northern Colorado mountain-plain system. Copyright 1999 by the American Geophysical Union."
"6602479390;7004050581;","Modulation of cosmic ray precipitation related to climate",1999,"10.1029/1999GL900326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032746666&doi=10.1029%2f1999GL900326&partnerID=40&md5=a97beedae8715d7c902d5adcb78db1c8","High energy cosmic rays may influence the formation of clouds and thus impact weather and climate. Due to systematic solar wind changes, the intensity of cosmic rays incident on the magnetopause has decreased markedly during this century. The pattern of cosmic ray precipitation through the magnetosphere to the upper troposphere has also changed. Early in the century, the part of the troposphere open to cosmic rays of all energies was typically confined to a relatively small high-latitude region. As the century progressed the size of this region increased by over 25% and there was a 6.5° equatorward shift in the yearly averaged latitudinal position of the subauroral region in which cloud cover has been shown to be cosmic ray flux dependent. We suggest these changes in cosmic ray intensity and latitude distribution may have influenced climate change during the last 100 years. Copyright 1999 by the American Geophysical Union."
"56537463000;7410255460;7004479957;","Three-Dimensional Week-Long Simulations of TOGA COARE Convective Systems Using the MM5 Mesoscale Model",1999,"10.1175/1520-0469(1999)056<2326:TDWLSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032761941&doi=10.1175%2f1520-0469%281999%29056%3c2326%3aTDWLSO%3e2.0.CO%3b2&partnerID=40&md5=ecdad8878722fd131353958d8ccc996b","A three-dimensional nonhydrostatic mesoscale model, the Pennsylvania State University/National Center for Atmospheric Research mesoscale model (MM5), is used to simulate the evolution of convective systems over the intensive flux array (IFA) during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment, during 19-26 December 1992. The model is driven by a time-varying ""IFA mean forcing"" based on the average advcctive tendencies of temperature and moisture over the IFA. The domain-averaged horizontal wind is kept close to the observed IFA mean using Newtonian relaxation. Periodic lateral boundary conditions are imposed. Simulations with three horizontal grid spacings, 2, 15, and 60 km, are conducted. With 15- and 60-km resolution, subgrid-scale cumulus convection is parameterized while mesoscale convective organization is explicitly resolved over a (600 km)! domain. With 2-km resolution, convection is fully resolved over a (210 km)2 domain. Despite their different horizontal resolution and different treatment of moist convection, the simulations all produce very similar temporal variability in domain-averaged temperature and relative humidity profiles. They also closely resemble each other in various statistical properties of convective systems. A comprehensive comparison of the 15- and 2-km model results against observations is performed. The domain-averaged cloud amount and precipitation agree well with observations. Some shortcomings are noted. During suppressed convective periods, the model tends to have greater areal coverage of rainfall and more cirrus anvil clouds than observed. Over the 8-day period, both models produce mean temperature drifts about 2 K colder than observed. A histogram of modeled cloud-top temperature captures the observed breaks between convective episodes but shows excessive and persistent cold cirrus clouds. A radar reflectivity histogram shows that the 15-km model slightly overpredicts radar reflectivity and that the 2-km model has too high and temporally homogeneous reflectivities. The modelsimulated cloud cluster size is somewhat smaller than the observed. Surface sensible and latent heat fluxes are overestimated by 50%-100%, due both to shortcomings in the surface flux calculations in the model and modelproduced mean temperature and humidity biases. Downwelling solar flux at the surface is underestimated mainly because of the simple shortwave radiation scheme. This study suggests that large-domain simulations using the MM5 with 15-km resolution can be a useful tool for further study of tropical convective organization and its interaction with large-scale circulation. © 1999 American Meteorological Society."
"36705143500;56250185400;","Radiative Forcing of a Tropical Direct Circulation by Soil Dust Aerosols",1999,"10.1175/1520-0469(1999)056<2403:RFOATD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032762103&doi=10.1175%2f1520-0469%281999%29056%3c2403%3aRFOATD%3e2.0.CO%3b2&partnerID=40&md5=a5032f5529ebf0736d8f230f248f762a","The effect of soil dust aerosols upon the tropical climate is estimated by forcing a simple model of a tropical direct circulation. The model consists of a region vertically mixed by deep convection and a nonconvecting region, for which budgets of dry static energy and moisture are constructed. Dynamical effects are included implicitly, by prohibiting horizontal temperature contrasts above the boundary layer. Dust aerosols absorb sunlight to a greater extent than industrial sulfate and sea-salt aerosols. In a companion study, where the climate response to dust is calculated using an atmospheric general circulation model, the global-average dust radiative forcing is negligible at the top of the dust layer, in comparison to the large reduction of the net flux at the surface. Thus, dust aerosols redistribute radiative heating from the surface into the dust layer, unlike industrial sulfates and sea salt, which through reflection reduce the total radiative energy gained by the column. The simple model is perturbed by a reduction in the net radiative flux at the surface. Forcing at the top of the dust layer is idealized to be zero. Cooling occurs at the surface of the nonconvecting region, but surface temperature within the convecting region is only slightly perturbed. It is shown that the disproportionately small response within the convecting region is a consequence of the trivial radiative forcing at the top of the dust layer, and the occurrence of deep convection, which prevents the surface temperature from changing without a corresponding change of the emitting temperature in the upper troposphere. Additional experiments, where the absorptivity of the dust particles is varied, indicate that the anomalous surface temperature is most sensitive to the radiative forcing at the top of the dust layer. The reduction of the surface net radiation is less important per se but introduces an asymmetry in the response between the convecting and nonconvecting regions through the radiative forcing within the dust layer, which is the difference between the forcing at the surface and the layer top. This heating can offset radiative cooling above the boundary layer, reducing the strength of the circulation that links the nonconvecting and convecting regions. The weakened circulation requires cooling of the nonconvecting region relative to the convecting region in order to maintain the export of energy from the latter to the former. It is suggested that the ""semi-indirect"" effect of aerosols, wherein cloud cover is changed in response to aerosol heating, is sensitive to the vertical extent and magnitude of the aerosol forcing. The experiments suggest that dust optical properties (to which the top of the atmosphere forcing is sensitive) should be allowed to vary with the mineral composition of the source region in a computation of the climate response. More extensive measurements of the dust optical properties, along with the vertical distribution of the dust layer, are needed to reduce the uncertainty of the climate response to dust aerosols. © 1999 American Meteorological Society."
"7003535176;6602831555;","Comment on “Variation of cosmic ray flux and global cloud coverage — a missing link in solar-climate relationships” by H. Svensmark and E. Friis-Christensen (1997)",1999,"10.1016/S1364-6826(99)00040-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994907992&doi=10.1016%2fS1364-6826%2899%2900040-1&partnerID=40&md5=1dcf4100b1a26a4b6505f3feb1478e7e",[No abstract available]
"35475623000;35779049500;57201282288;57205899909;7003450239;7201993533;35426110900;7004065709;","Arctic haze and clouds observed by lidar during four winter seasons of 1993-1997, at Eureka, Canada",1999,"10.1016/S1352-2310(98)00397-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033167855&doi=10.1016%2fS1352-2310%2898%2900397-5&partnerID=40&md5=5b737474d447be39e58785aefefc2178","A Mie-scattering-polarized Haze Lidar was installed at Eureka, Canada (80°N, 86°W), in February 1993 and has been used to observe the arctic haze during winter seasons from 1993-94 to 1996-97. Although it is difficult to distinguish between the arctic haze and other scattering objects (mainly clouds) under the specific conditions, two methods were used to classify those objects into two groups. First the vertical profiles of the arctic haze and clouds were compared with meteorological data observed by a radiosonde, and the relations between the scattering and depolarization ratios and the meteorological data were investigated. Then, since the arctic haze had very stable layers, the time dependency of the correlation coefficient between the different vertical profiles for the arctic haze and clouds was investigated. After the scattering objects were classified into two groups (the arctic haze and the clouds), the scattering ratio, the depolarization ratio, and the occurrence probabilities of them were investigated statistically. The statistical results, from the observations over the last four winter seasons, indicate that the average values of the scattering and depolarization ratios of the arctic haze were respectively 1.27 and 1.34%. The average humidity over ice of the layer containing the arctic haze was 42 ± 19% (cloud: 92 ± 13%). The arctic haze was observed at altitudes less than 3 km frequently and at altitudes of 3-5 km occasionally."
"6603566437;7403076976;","Ionospheric potential as a proxy index for global temperature",1999,"10.1016/S0169-8095(99)00015-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032718438&doi=10.1016%2fS0169-8095%2899%2900015-0&partnerID=40&md5=6f82b866a567ac82f4000d4141585033","Since the global circuit is maintained by currents from thunderstorms and electrified clouds, which are controlled by temperature, we are investigating the use of ionospheric potential (V(I)) as a measure of the variation of global temperature. We report positive correlation between V(I) and global temperature obtained from three different data sets. V(I) is also positively correlated with an inferred global lightning/deep cloud index which is positively correlated with global temperature. Thus, there is a consistent picture of warmer temperatures leading to more deep convection and higher V(I). Since a series of single V(I) soundings at any appropriate location may provide a globally representative measure of temperature variation in real time, it is suggested that routine monitoring of this parameter could provide considerable cost and operational advantages compared to current methodology involving observations at thousands of ground stations and satellite radiation measurements."
"7005913201;7006324813;","Consequences of a change in the Galactic environment of the sun",1999,"10.1086/307320","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033587309&doi=10.1086%2f307320&partnerID=40&md5=58fe2938e50adfd09b6faf7ba5773d56","The interaction of the heliosphere with interstellar clouds has attracted interest since the late 1920s, with a view to explaining apparent both quasi-periodic climate ""catastrophes"" as well as periodic mass extinctions. Until recently, however, models describing the solar wind-local interstellar medium (LISM) interaction self-consistently had not been developed. Here we describe the results of a two-dimensional simulation of the interaction between the heliosphere and an interstellar cloud with the same properties as currently, except that the H0 density is increased from the present value of n(H0) ∼ 0.2 cm-3 to 10 cm-3. The mutual interaction of interstellar neutral hydrogen and plasma is included. The heliospheric cavity is reduced considerably in size (approximately 10-14 AU to the termination shock in the upstream direction) and is highly dynamical. The interplanetary environment at the orbit of the Earth changes markedly, with the density of interstellar H0 increasing to ∼2 cm-3. The termination shock itself experiences periods where it disappears, reforms, and disappears again. Considerable mixing of the shocked solar wind and LISM occurs because of Rayleigh-Taylor-like instabilities at the nose, driven by ion-neutral friction. Implications of two anomalously high concentrations of 10Be found in Antarctic ice cores, corresponding to 33,000 and 60,000 yr ago, and the absence of prior similar events are discussed in terms of density enhancements in the surrounding interstellar cloud. The calculation presented here supports past speculation that the Galactic environment of the Sun moderates the interplanetary environment at the orbit of the Earth and possibly also the terrestrial climate."
"7006351262;6506465593;7004159166;56490302800;7101638253;7004140528;7006086673;7005219614;","Tropospheric O3 distribution over the Indian Ocean during spring 1995 evaluated with a chemistry-climate model",1999,"10.1029/1999JD900176","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001340069&doi=10.1029%2f1999JD900176&partnerID=40&md5=ccbb62c0faf010051f2a60c4a1dd7011","An analysis of tropospheric O3 over the Indian Ocean during spring 1995 is presented based on O3 soundings and results from the European Centre Hamburg (ECHAM) chemistry-general circulation model. The ECHAM model is nudged toward actual meteorology using European Centre for Medium-Range Weather Forecasts analyses, to enable a direct comparison between model results and in situ observations. The model reproduces observed CO levels in different air mass categories. The model also reproduces the general tendencies and the diurnal variation in the observed surface pressure, although the amplitude of the diurnal variation in the amplitude is underestimated. The model simulates the general O3 tendencies as seen in the sonde observations. Tropospheric O3 profiles were characterized by low surface concentrations (&lt;10 ppbv), midtropospheric maxima (60-100 ppbv, at 700-250 hPa) and upper tropospheric minima (&lt;20 ppbv, at 250-100 hPa). Large-scale upper tropospheric O3 minima were caused by convective transport of O3-depleted boundary layer air in the intertropical convergence zone (ITCZ). Similarly, an upper tropospheric O3 minimum was caused by Cyclone Marlene south of the ITCZ. The midtropospheric O3 maxima were caused by transport of polluted African air. The ECHAM model appears to overestimate surface O3 levels and does not reproduce the diurnal variations very well. This could be related to unaccounted multiphase O3 destruction mechanisms involving low level clouds and aerosols, and missing halogen chemistry. Copyright 1999 by the American Geophysical Union."
"7003668116;7005135473;","Daytime variation of marine stratocumulus microphysical properties as observed from geostationary satellite",1999,"10.1029/1999GL900346","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033563620&doi=10.1029%2f1999GL900346&partnerID=40&md5=c58018093538e851432e598cf69ca7f8","Daytime changes in the droplet effective radius (re) and cloud liquid water path (LWP) were examined over a large area of marine stratocumulus off the coast of California over a six-day period using Geostationary Operational Environmental Satellite (GOES) 9 imager measurements. Amplitude and phase of the first harmonic of the Fourier series were used to represent the daytime cycle. Complex spatial variation in the amplitude was found. Mean amplitudes were 0.65 μm (re) and 13.8 g m-2 (cloud LWP). For cloud LWP the cycle peaked predominantly in the morning while re maxima occurred in both morning and afternoon. While attention has focused on the re afternoon maximum, these observations show that in fact the morning maximum is more common and has a stronger cycle, underscoring the poorly understood nature of the diurnal cycle of marine stratocumulus microphysical properties. Copyright 1999 by the American Geophysical Union."
"7201966094;7401844779;","Estimation of aerosol direct radiative effects over the mid-latitude North Atlantic from satellite and in situ measurements",1999,"10.1029/1999GL900330","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033563597&doi=10.1029%2f1999GL900330&partnerID=40&md5=425866a85b2d3acfd6225ce563162e0e","We estimate solar radiative flux changes due to aerosols over the mid-latitude North Atlantic by combining optical depths from AVHRR measurements with aerosol properties from the recent TARFOX program. Results show that, over the ocean, the aerosol decreases the net radiative flux at the tropopause and therefore has a cooling effect. Cloud-free, 24-hour average flux changes range from -9 W/m2 near the eastern US coast in summer to -1 W/m2 in the mid-Atlantic during winter. Cloud-free North Atlantic regional averages range from -5.1 W/m2 in summer to -1.7 W/m2 in winter, with an annual average of -3.5 W/m2. Cloud effects, estimated from ISCCP data, reduce the regional annual average to -0.8 W/m2. All values are for the moderately absorbing TARFOX aerosol (ω(0.55 μm) = 0.9); values for a nonabsorbing aerosol are ∼30% more negative. We compare our results to a variety of other calculations of aerosol radiative effects. Copyright 1999 by the American Geophysical Union."
"7402363038;7006256622;7005548544;","Tropospheric water vapor and climate sensitivity",1999,"10.1175/1520-0469(1999)056<1649:TWVACS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033149869&doi=10.1175%2f1520-0469%281999%29056%3c1649%3aTWVACS%3e2.0.CO%3b2&partnerID=40&md5=55ea6f27d7250ecce5926cf5489f13f6","Estimates are made of the effect of changes in tropospheric water vapor on the climate sensitivity to doubled carbon dioxide (CO2), using a coarse resolution atmospheric general circulation model coupled to a slab mixed layer ocean. The sensitivity of the model to doubled CO2 is found as the difference between the equilibrium responses for control and doubled CO2 cases. Clouds are specified to isolate the water vapor feedback. Experiments in which the water vapor distribution is specified rather than internally calculated are used to find the contribution of water vapor in various layers and latitude belts to the sensitivity. The contribution of water vapor in layers of equal mass to the climate sensitivity varies by about a factor of 2 with height, with the largest contribution coming from layers between 450 and 750 mb, and the smallest from layers above 230 mb. The positive feedback on the global mean surface temperature response to doubled CO2 from water vapor above 750 mb is about 2.6 times as large as that from water vapor below 750 mb. The feedback on global mean surface temperature due to water vapor in the extratropical free troposphere (above 750 mb) is about 50% larger than the feedback due to the lower-latitude free troposphere water vapor. Several important sources of nonlinearity of the radiative heating rates were identified in the process of constructing the specified cloud and water vapor fields. These are (i) the interaction of clouds and solar radiation, which produces much more reflection of solar radiation for time mean clouds than for the instantaneous clouds; (ii) the correlation of clouds and water vapor, which produces less downward longwave radiation at the ground for correlated clouds and water vapor than when these fields are independent; and (iii) the interaction of water vapor with longwave radiation, which produces less downward longwave radiation at the ground for the average over instantaneous water vapor distributions than for the time mean water vapor distribution.Estimates are made of the effect of changes in tropospheric water vapor on the climate sensitivity to doubled carbon dioxide (CO2), using a coarse resolution atmospheric general circulation model coupled to a slab mixed layer ocean. The sensitivity of the model to doubled CO2 is found as the difference between the equilibrium responses for control and doubled CO2 cases. Clouds are specified to isolate the water vapor feedback. Experiments in which the water vapor distribution is specified rather than internally calculated are used to find the contribution of water vapor in various layers and latitude belts to the sensitivity. The contribution of water vapor in layers of equal mass to the climate sensitivity varies by about a factor of 2 with height, with the largest contribution coming from layers between 450 and 750 mb, and the smallest from layers above 230 mb. The positive feedback on the global mean surface temperature response to doubled CO2 from water vapor above 750 mb is about 2.6 times as large as that from water vapor below 750 mb. The feedback on global mean surface temperature due to water vapor in the extratropical free troposphere (above 750 mb) is about 50% larger than the feedback due to the lower-latitude free troposphere water vapor. Several important sources of nonlinearity of the radiative heating rates were identified in the process of constructing the specified cloud and water vapor fields. These are (i) the interaction of clouds and solar radiation, which produces much more reflection of solar radiation for time mean clouds than for the instantaneous clouds; (ii) the correlation of clouds and water vapor, which produces less downward longwave radiation at the ground for correlated clouds and water vapor than when these fields are independent; and (iii) the interaction of water vapor with longwave radiation, which produces less downward longwave radiation at the ground for the average over instantaneous water vapor distributions than for the time mean water vapor distribution."
"7403076976;57202409199;15830044700;7005395283;","Long term changes in diurnal temperature range in Cyprus",1999,"10.1016/S0169-8095(99)00022-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032873798&doi=10.1016%2fS0169-8095%2899%2900022-8&partnerID=40&md5=bfbbcfcf0c1ab904d003f538a9534402","Long term temperature data from two stations on the island of Cyprus have been analysed. Increasing trends of approximately 1°C/100 years in the annual mean temperatures are found at both stations. However, the minimum daily temperatures have generally increased at a larger rate than the maximum daily temperatures, resulting in a decrease in the long-term diurnal temperature range. This decrease ranges from -0.5°C/100 years to -3.5°C/100 years, depending on the location. The reduction in the diurnal temperature range is consistent with observations from other parts of the globe, and may indicate that the climate in this region of the globe is part of a larger global climate change that has been occurring over the last century. It is possible that long term changes in greenhouse gas concentrations in the atmosphere are responsible for the long-term annual mean temperature increase. Furthermore, the changes in the diurnal temperature range can possibly be explained by increases in cloud cover and/or tropospheric aerosols. It is possible that part of these changes is caused by local land-use changes, primarily by the increasing urbanization of Cyprus."
"7006184606;6503903054;","Development and evaluation of a convection scheme for use in climate models",1999,"10.1175/1520-0469(1999)056<1766:DAEOAC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0344433876&doi=10.1175%2f1520-0469%281999%29056%3c1766%3aDAEOAC%3e2.0.CO%3b2&partnerID=40&md5=d1bcf184a275c540ae759eb1d4945c7f","Cumulus convection is a key process in controlling the water vapor content of the atmosphere, which is in turn the largest feedback mechanism for climate change in global climate models. Yet scant attention has been paid to designing convective representations that attempt to handle water vapor with fidelity, and even less to evaluating their performance. Here the authors attempt to address this deficiency by designing a representation of cumulus convection with close attention paid to convective water fluxes and by subjecting the scheme to rigorous tests using sounding array data. The authors maintain that such tests, in which a single-column model is forced by large-scale processes measured by or inferred from the sounding data, must be carried out over a period at least as long as the radiative-subsidence timescale-about 30 days-governing the water vapor adjustment time. The authors also argue that the observed forcing must be preconditioned to guarantee integral enthalpy conservation, else errors in the single-column prediction may be falsely attributed to convective schemes. Optimization of the new scheme's parameters is performed using one month of data from the intensive flux array operating during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment, with the aid of the adjoint of the linear tangent of the single-column model. Residual root-mean-square errors, after optimization, are about 15% in relative humidity and 1.8 K in temperature. It is difficult to reject the hypothesis that the residual errors are due to noise in the forcing. Evaluation of the convective scheme is performed using Global Atmospheric Research Program Atlantic Tropical Experiment data. The performance of the scheme is compared to that of a few other schemes used in current climate models. It is also shown that a vertical resolution better than 50 mb in pressure is necessary for accurate prediction of atmospheric water vapor.Cumulus convection is a key process in controlling the water vapor content of the atmosphere, which is in turn the largest feedback mechanism for climate change in global climate models. Yet scant attention has been paid to designing convective representations that attempt to handle water vapor with fidelity, and even less to evaluating their performance. Here the authors attempt to address this deficiency by designing a representation of cumulus convection with close attention paid to convective water fluxes and by subjecting the scheme to rigorous tests using sounding array data. The authors maintain that such tests, in which a single-column model is forced by large-scale processes measured by or inferred from the sounding data, must be carried out over a period at least as long as the radiative-subsidence timescale - about 30 days - governing the water vapor adjustment time. The authors also argue that the observed forcing must be preconditioned to guarantee integral enthalpy conservation, else errors in the single-column prediction may be falsely attributed to convective schemes. Optimization of the new scheme's parameters is performed using one month of data from the intensive flux array operating during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment, with the aid of the adjoint of the linear tangent of the single-column model. Residual root-mean-square errors, after optimization, are about 15% in relative humidity and 1.8 K in temperature. It is difficult to reject the hypothesis that the residual errors are due to noise in the forcing. Evaluation of the convective scheme is performed using Global Atmospheric Research Program Atlantic Tropical Experiment data. The performance of the scheme is compared to that of a few other schemes used in current climate models. It is also shown that a vertical resolution better than 50 mb in pressure is necessary for accurate prediction of atmospheric water vapor."
"57217887278;7004411975;7005492211;","Determination of trifluoroacetic acid in 1996-1997 precipitation and surface waters in California and Nevada",1999,"10.1021/es980697c","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033562429&doi=10.1021%2fes980697c&partnerID=40&md5=83f7743f6827cc750f3f968a6d1e6d6f","The atmospheric degradation of three chlorofluorocarbon (CFC) replacement compounds, namely HFC-134a, HCFC-123, and HCFC-124, results in the formation of trifluoroacetic acid (TFA). Concentrations of TFA were determined in precipitation and surface water samples collected in California and Nevada during 1996-1997. Terminal lake systems were found to have concentrations 4-13 times higher than their calculated yearly inputs, providing evidence for accumulation. The results support dry deposition as the primary contributor of TEA to surface waters in arid and semiarid environments. Precipitation samples obtained from three different locations contained 20.7-1530 ng/L with significantly higher concentrations in fogwater (median = 689 ng/L) over rainwater (median = 63.7 ng/L). Elevated levels of TFA were observed for rainwater collected in Nevada (median = 136 ng/L) over those collected in California (median = 49.5 ng/L), indicating continual uptake and concentration as clouds move from a semiarid to arid climate. Thus several mechanisms exist, including evaporative concentration, vapor-liquid phase partitioning, lowered washout volumes of atmospheric deposition water, and dry deposition, which may lead to elevated concentrations of TFA in atmospheric and surface waters above levels expected from usual rainfall washout.The atmospheric degradation of three chlorofluorocarbon (CFC) replacement compounds, namely HFC-134a, HCFC-123, and HCFC-124, results in the formation of trifluoroacetic acid (TFA). Concentrations of TFA were determined in precipitation and surface water samples collected in California and Nevada during 1996-1997. Terminal lake systems were found to have concentrations 4-13 times higher than their calculated yearly inputs, providing evidence for accumulation. The results support dry deposition as the primary contributor of TFA to surface waters in arid and semiarid environments. Precipitation samples obtained from three different locations contained 20.7-1530 ng/L with significantly higher concentrations in fogwater (median = 689 ng/L) over rainwater (median = 63.7 ng/L). Elevated levels of TFA were observed for rainwater collected in Nevada (median = 136 ng/L) over those collected in California (median = 49.5 ng/L), indicating continual uptake and concentration as clouds move from a semiarid to arid climate. Thus several mechanisms exist, including evaporative concentration, vapor-liquid phase partitioning, lowered washout volumes of atmospheric deposition water, and dry deposition, which may lead to elevated concentrations of TFA in atmospheric and surface waters above levels expected from usual rainfall washout."
"56157800800;","Examining the sensitivity of Earth's climate to the removal of ozone, landmasses and enhanced ocean heat transport in the GENESIS global climate model",1999,"10.1016/S0921-8181(98)00070-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032793722&doi=10.1016%2fS0921-8181%2898%2900070-8&partnerID=40&md5=25657cc5db46d69fdcaf29fd82a705db","This paper examines the cloud radiative forcing and its impacts on the surface climate for global climate model simulations that use reduced ozone concentrations and land fractions as boundary conditions. In one simulation using present-day land continents, ozone concentrations are reduced to zero and compared to the present-day climate simulation. In the second set of simulations under global ocean conditions, the implied poleward transport of heat by the ocean is varied. The removal of ozone causes an increase in longwave cloud radiative forcing at the top of the atmosphere and the surface. The increase in longwave forcing melts sea-ice and snow at high latitudes leading 10-14°C warmer temperatures and globally a 2°C increase. The global ocean simulations lead to higher cloud fractions than present-day simulation. Without poleward transport of heat by the ocean, surface temperatures cool as a result of higher cloud fractions. Increasing the ocean heat transport by a factor of 3.33 brings about ice-free conditions. An 11°C difference in globally averaged surface air temperatures is found between the enhanced and zero poleward oceanic heat transport simulations. The longwave cloud radiative forcing from high cloud fractions enhance the surface warming in the polar regions during the winter season. Conversely, during the summer season, a high cloud fraction increases the shortwave cloud radiative forcing producing only moderately warm temperatures in the polar regions. High cloud fractions in polar regions during warm periods throughout geologic times may help to explain the reduced equator to pole temperature gradient."
"35572096100;7007108728;7102331727;","Ice particle habits in Arctic clouds",1999,"10.1029/1999GL900232","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033134086&doi=10.1029%2f1999GL900232&partnerID=40&md5=451d797bd854229472cbe3843b51755c","Ice crystals in atmospheric clouds have shapes, which affect their density, terminal fall velocity, growth rate and radiative properties. In calculations for climate change predictions, weather forecasting of precipitation, and remote sensing retrievals, idealized crystal shapes such as columns, ' needles, plates and dendrites are assumed. Using new technology imaging instrumentation with a resolution of 2.3 (im, recent observations in Arctic clouds have shown that such pristine habits only describe approximately 3% of the particles. The measurements were made from an aircraft during April 1998 and cover a temperature range of 0 °C to -45 °C. Boundary layer, multi-layer and cirrus clouds were examined. The commonly observed irregularly shaped particles either consisted of faceted polycrystalline particles or sublimating (solid to vapor) ice particles with smooth curving sides and edges. Since climate warming is now predicted to be largest in the Arctic, and cloud properties significantly affect the radiation balance, it will be necessary to consider the effects of non-pristine ice particle habits in such calculations and predictions. Copyright 1999 by the American Geophysical Union."
"55416611500;","The ocean's role in climate variability and change and the resulting impacts on coasts",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033053985&partnerID=40&md5=8256d44dcab16397e799f39fb352b645","This article describes the oceans' influence on weather and climate and identifies selected global climate change impacts on coastal areas. It is divided into three parts: seasonal to inter-annual climate impacts; decadal to centennial climate impacts; and coastal global climate change impacts. The article describes how the weather and climate are driven by the redistribution of heat. The major source of heat to the surface of the earth is the sun, principally through incoming visible radiation. Most of it is absorbed by the earth's surface. This radiation is redistributed by the ocean and the atmosphere and the excess is radiated back into space as longer wavelength, infrared radiation. Clouds and other gases, primarily water vapour and carbon dioxide, absorb the infrared radiation emitted by the earth's surface and reemit their own heat at much lower temperatures. This 'traps' the earth's radiation and makes the earth much warmer than it would be otherwise. Most of the incoming solar radiation is received in tropical regions, while very little is received in polar regions especially during winter months. Over time, energy absorbed near the equator spreads to the colder regions of the globe, carried by winds in the atmosphere and by currents in the oceans. Compared to the atmosphere, the ocean is much denser and has a much greater ability to store heat. The oceans also move much more slowly than the atmosphere. Thus, the oceans and the atmosphere interact on different time scales. The ocean moderates seasonal variations; it stores and transports, via ocean currents, large amounts of heat around the globe, resulting in changing weather patterns. While global climate has fluctuated throughout time, a global warming scenario could speed climate change, possibly causing accelerated sea-level rise, alterations of rainfall patterns and storm frequency or intensity, and increased siltation. This in turn could result in the increased erosion of shores and associated habitat, increased salinity of estuaries and freshwater aquifers, altered tidal ranges in rivers and bays, changes in sediment and nutrient transport, a change in the pattern of chemical and biological contamination in coastal areas, and increased coastal flooding. Some coastal ecosystems are particularly at risk, including saltwater marshes, coastal wetlands, coral reefs, coral atolls, and river deltas. Other critical coastal resources, such as mangroves and seagrass beds, submerged and mudflats, are at risk from climate change impacts, exacerbated by anthropogenic factors. Changes in these ecosystems could have major negative effects on tourism, freshwater supplies, fisheries, and biodiversity that could make coastal impacts an important economic concern. Coastal structures, including homes would also be more vulnerable to increased sea-levels. A number of alternative management strategies are discussed, as are some of the difficulties of convincing the public of the need for action."
"7101679850;","Analysis of Hong Kong daily bulk and wet deposition data from 1994 to 1995",1999,"10.1016/S1352-2310(98)00340-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033137021&doi=10.1016%2fS1352-2310%2898%2900340-9&partnerID=40&md5=5d2265dbd3bcd4bce42f23731943f3a5","Results from a 1-year daily rainwater sampling program, employing both wet and bulk deposition samplers with replicate samples, from 1994 to 1995 in Hong Kong are presented and analysed. Analyte concentrations were found to vary over a wide range of several orders of magnitude, with [H+] for example, from 0.16 to 208.9 μeq dm-3. Diurnal pH values less than 3.83 were measured on five occasions. A significant correlation between pH and lognormal windspeed has been found. This is taken to indicate the minor importance of long-range transport in determining rainwater acidity, since local pollutant emissions accumulate and react under conditions of atmospheric stability in the sub-tropical climate. The H+ wet deposition flux onto a polythene surface was 90 meq m-2 yr-1 during 1994-1995 at City University. Dry deposition exerts a neutralizing influence upon the acidity from this wet deposition. Although paired t-tests indicated significant differences between the bulk versus wet deposition datasets for cations, but not anions, the dataset means consequently showed such large standard deviations that t-tests indicated no significant differences. In rainwater, the charges from SO4/2- and NO3/- anions seldom balance the proton charges, implying that they are also derived from solubilization of primary and secondary airborne Ca2+, Mg2+ and NH4/+ particulate matter in rainwater. Use of the [SO4/2-]/[NO3/-] ratios in rainwater in fingerprinting pollutant origins has drawbacks, but is generally indicative of a predominantly regional contribution of these secondary pollutants to rainwater. Bulk deposition pH in Hong Kong would be in the region of 4.1 if basic Ca2+ compounds alone did not neutralize acidity. The regional rainout pH, inferred after exhaustive below-cloud scavenging, is about 5. The temporal trends in Hong Kong rainwater acidity are blurred.Results from a 1-year daily rainwater sampling program, employing both wet and bulk deposition samplers with replicate samples, from 1994 to 1995 in Hong Kong are presented and analyzed. Analyte concentrations were found to vary over a wide range of several orders of magnitude, with [H-] for example, from 0.16 to 208.9 μeq dm-3. Diurnal pH values less than 3.83 were measured on five occasions. A significant correlation between pH and lognormal windspeed has been found. This is taken to indicate the minor importance of long-range transport in determining rainwater acidity, since local pollutant emissions accumulate and react under conditions of atmospheric stability in the sub-tropical climate. The H- wet deposition flux onto a polythene surface was 90 meq m-2 yr-1 during 1994-1995 at City University. Dry deposition exerts a neutralizing influence upon the acidity from this wet deposition. Although paired t-tests indicated significant differences between the bulk versus wet deposition datasets for cations, but not anions, the dataset means consequently showed such large standard deviations that t-tests indicated no significant differences. In rainwater, the charges from SO42- and NO3- anions seldom balance the proton charges, implying that they are also derived from solubilization of primary and secondary airborne Ca2+, Mg2+ and NH4+ particulate matter in rainwater. Use of the [SO42-]/[NO3-] ratios in rainwater in fingerprinting pollutant origins has drawbacks, but is generally indicative of a predominantly regional contribution of these secondary pollutants to rainwater. Bulk deposition pH in Hong Kong would be in the region of 4.1 if basic Ca2+ compounds alone did not neutralize acidity. The regional rainout pH, inferred after exhaustive below-cloud scavenging, is about 5. The temporal trends in Hong Kong rainwater acidity are blurred."
"57201726470;7501757094;","An interactive cirrus cloud radiative parameterization for global climate models",1999,"10.1029/1999JD900026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608923&doi=10.1029%2f1999JD900026&partnerID=40&md5=0a84836c7563cb0459970f2441b9ba8b","An interactive cirrus cloud radiative parameterization is developed for global climate models from recent observations and analytical results that more accurately characterize cirrus cloud optical and microphysical properties. The radiative properties are based on the assumption that cirrus clouds are composed of hexagonal crystals. For the infrared component, a new mass absorption coefficient is parameterized to calculate emissivity, and for the solar, single-scattering properties from an existing parameterization are modified and employed. The solar and infrared optical properties are given as a function of ice water content and effective particle size. Aircraft observations are used to parameterize the microphysical properties in terms of temperature, thus allowing the radiative properties to interact with the local model climate. The interactive cirrus radiative parameterization is evaluated in model-to-observation comparisons with a comprehensive set of cloud and radiation measurements obtained during the spring 1994 and fall 1995 Intensive Observation Periods of the Atmospheric Radiation Measurement program. It is shown that the model with the new parameterization calculates realistic infrared radiation and improved solar radiation incident at the surface. Specifically, biases in calculated solar direct and diffuse fluxes are reduced by 60 and 40%, respectively. Further, the shortwave flux is shown to be more sensitive than the longwave flux to variability in the ice water content and in the base and top heights of observed clouds replicated in model calculations. The potential effect of the new parameterization on climate simulations is investigated in the context of initial radiative forcing. The new parameterization calculates a significantly different ice water path distribution from an existing parameterization that has been used for global climate change studies. For example, in the high latitudes of the summer hemisphere the new ice water path is larger by more than 7.7 g m-2 (&gt;100%), and in the tropics it can be smaller by as much as -3.5 g m-2 (∼80%). These differences lead to an increased solar albedo effect in the high latitudes of the summer hemisphere and a decreased greenhouse effect in the tropics, both of which contribute to a smaller, 2.26 W m-2, global- and annual-mean forcing of the surface-troposphere system. Copyright 1999 by the American Geophysical Union."
"6603809220;","Indirect forcing by anthropogenic aerosols: A global climate model calculation of the effective-radius and cloud-lifetime effects",1999,"10.1029/1998JD900009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608899&doi=10.1029%2f1998JD900009&partnerID=40&md5=2642b05b6fe03ebf2120705a665f29fe","A global climate model (GCM) that includes a physically based cloud scheme is used to calculate the indirect radiative forcing due to the modification of liquid-water cloud properties by anthropogenic aerosols. The distribution of cloud-droplet number concentration Nd required by the cloud scheme is estimated empirically from monthly mean fields of sulfate mass generated by a chemical transport model. The effects of anthropogenic changes in Nd are considered in the calculation of precipitation (the ""cloud-lifetime"" effect) and of the droplet effective radius used in the shortwave and longwave radiation schemes (the ""effective-radius"" effect). The modeled cloud-droplet effective radii for present-day conditions agree quite well with satellite-retrieved values, although the land-ocean and hemispheric contrasts are weaker in the model than in the observations. The total indirect forcing is -2.1 W m-2, including a small longwave forcing of +0.1 W m-2. The forcing results from a 1% increase in cloudiness, a 6% increase in liquid water path, and a 7% decrease in droplet effective radius. The breakdown of the total indirect forcing into the effective-radius and cloud-lifetime effects is estimated by performing separate GCM experiments in which each effect is included individually. The estimated forcings due to the effective-radius and cloud-lifetime effects are -1.2 and -1.0 W m-2, respectively. The calculated forcings show some sensitivity to the auto conversion threshold, the sulfate-Nd relation, and the vertical distribution of sulfate, but in each case the cloud-lifetime forcing is at least 25% of the total indirect forcing. These results suggest that the cloud-lifetime effect should not be ignored in future calculations of the indirect forcing due to anthropogenic aerosols. Copyright 1999 by the American Geophysical Union."
"55957189000;35592560600;6701650285;","A one and half year interactive MA/ECHAM4 simulation of Mount Pinatubo Aerosol",1999,"10.1029/1999JD900088","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608894&doi=10.1029%2f1999JD900088&partnerID=40&md5=7ea7e13bbdeac254902257e02d01eba0","The Mount Pinatubo volcanic eruption in June 1991 had significant impact on stratospheric and tropospheric climate and circulation. Enhanced radiative heating caused by the aerosol absorption of solar and terrestrial radiation changed stratospheric temperature and circulation. Using the stratospheric mesospheric version of the Hamburg climate model MA/ECHAM4, we performed an interactive Pinatubo simulation with prognostic stratospheric aerosol. Interactive and noninteractive model results for the years 1991 and 1992 are compared with satellite data and in situ measurements. The on-line calculated heating rates are in good agreement with radiation transfer models indicating maximum heating rates of about 0.3 K/d in October 1991. The dynamic feedback in the MA/ECHAM4 simulation is similar to observations. The model is able to reproduce the strengthening of the polar vortex in winter 1991/1992 and a minor warming in January. The importance of an interactive treatment of the volcanic cloud for the aerosol transport is evidenced by the analysis of effects such as aerosol lifting and meridional transport. In general, the model results agree well with observations from the northern midlatitudes, especially in the first months after the eruption. The MA/ECHAM4 model is successful in reproducing the formation of two distinct maxima in the optical depth but is unable to simulate the persistence of the tropical aerosol reservoir from the end of 1991. Better agreement may be achieved if the influence of the quasi-biennial oscillation and ozone changes is also taken into account. Copyright 1999 by the American Geophysical Union."
"35514163500;56744278700;","Radiative effects of CH4, N2O, halocarbons and the foreign-broadened H2O continuum: A GCM experiment",1999,"10.1029/1999JD900003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608941&doi=10.1029%2f1999JD900003&partnerID=40&md5=c9fe7558c50a7df329a54bc8af8c08bf","The simplified exchange approximation (SEA) method for calculation of infrared radiative transfer, used for general circulation model (GCM) climate simulations at the Geophysical Fluid Dynamics Laboratory (GFDL) and other institutions, has been updated to permit inclusion of the effects of methane (CH4), nitrous oxide (N2O), halocarbons, and water-vapor-air molecular broadening (foreign broadening). The effects of CH4 and N2O are incorporated by interpolation of line-by-line (LBL) transmissivity calculations evaluated at standard species concentrations; halocarbon effects are calculated from transmissivities computed using recently measured frequency-dependent absorption coefficients. The effects of foreign broadening are included by adoption of the ""CKD"" formalism for the water vapor continuum [Clough et al., 1989]. For a standard midlatitude summer profile, the change in the net infrared flux at the model tropopause due to the inclusion of present-day concentrations of CH4 and N2O is evaluated to within ∼5% of corresponding LBL results; the change in net flux at the tropopause upon inclusion of 1 ppbv of CFC-11, CFC-12, CFC-113, and HCFC-22 is within ∼10% of the LBL results. Tropospheric heating rate changes resulting from the introduction of trace species (CH4, N2O, and halocarbons) are calculated to within ∼0.03 K/d of the LBL results. Introduction of the CKD water vapor continuum causes LBL-computed heating rates to decrease by up to ∼0.4 K/d in the upper troposphere and to increase by up to ∼0.25 K/d in the midtroposphere; the SEA method gives changes within ∼0.05 K/d of the LBL values. The revised SEA formulation has been incorporated into the GFDL ""SKYHI"" GCM. Two simulations (using fixed sea surface temperatures and prescribed clouds) have been performed to determine the changes to the model climate from that of a control calculation upon inclusion of (1) the trace species and (2) the foreign-broadened water vapor continuum. When the trace species are added, statistically significant warming (∼1 K) occurs in the annual-mean tropical upper troposphere, while cooling (∼1.5 K) is noted in the upper stratosphere and stratopause region. The changes are generally similar to annual-mean equilibrium calculations made using a radiative-convective model assuming fixed dynamical heating. The effects of the CKD water vapor continuum include cooling (∼1 K) in the annual-mean troposphere above ∼6 km, with significant warming in the lower troposphere. When effects of both trace gases and the CKD continuum are included, the annual-mean temperature increases below ∼5 km and cools between 5 and 10 km, indicating that continuum effects dominate in determining temperature changes in the lower and middle troposphere. Above, trace gas effects dominate, resulting in warming in the tropical upper troposphere and cooling in most of the middle atmosphere. Clear-sky outgoing longwave irradiances have been computed for observed European Centre for Medium-Range Weather Forecasting atmospheric profiles using three versions of the SEA formulation, including the effects of (1) water vapor, carbon dioxide, and ozone; (2) the above species plus present-day concentrations of the new trace species; (3) all of the above species plus the CKD H2O continuum. Results for all three cases are within ∼10 W/m2 of corresponding Earth Radiation Budget Experiment clear-sky irradiance measurements. The combined effect of trace gases and the CKD continuum result in a decrease of ∼8 W/m2 in the computed irradiances."
"6505939631;7007010459;35512883100;","Some doubts concerning a link between cosmic ray fluxes and global cloudiness",1999,"10.1029/1999GL900121","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033117673&doi=10.1029%2f1999GL900121&partnerID=40&md5=782108ccad3beaf9e165232449d75548","Svensmark and Friis-Christensen (1997, henceforth SFC) showed a strong correlation between cosmic ray flux and ISCCP total cloudiness between 1984 and 1990. They concluded that ionisation by cosmic rays, more prevalent at times of lower solar activity, might explain apparent correlations between solar activity and climate through changes in cloud radiative forcing. We have extended SFC's approach with a study of the different cloud types, restricting our analysis to the period 1985 to 1988 during which the ISCCP calibration is believed to be stable. We find no clear relationship between individual cloud types and cosmic ray flux. Inclusion of data at high latitudes decreases the amplitude of the apparent correlation although ionisation by cosmic rays is greatest at high latitudes. Thin high cloud shows an increase throughout the period such that the combined effect of the changes in cloud types suggests an almost monotonic increase in cloud radiative forcing between 1985 and 1988 which is not related to cosmic ray activity.Svensmark and Friis-Christensen (1997, hence-forth SFC) showed a strong correlation between cosmic ray flux and ISCCP total cloudiness between 1984 and 1990. They concluded that ionisation by cosmic rays, more prevalent at times of lower solar activity, might explain apparent correlations between solar activity and climate through changes in cloud radiative forcing. We have extended SFC's approach with a study of the different cloud types, restricting our analysis to the period 1985 to 1988 during which the ISCCP calibration is believed to be stable. We find no clear relationship between individual cloud types and cosmic ray flux. Inclusion of data at high latitudes decreases the amplitude of the apparent correlation although ionisation by cosmic rays is greatest at high latitudes. Thin high cloud shows an increase throughout the period such that the combined effect of the changes in cloud types suggests an almost monotonic increase in cloud radiative forcing between 1985 and 1988 which is not related to cosmic ray activity."
"7004539332;7404678955;","The impact of vertical resolution upon GCM simulations of marine stratocumulus",1999,"10.1007/s003820050283","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032988499&doi=10.1007%2fs003820050283&partnerID=40&md5=88111151b48efc85f4d8571a91f19f6e","The impact of increased vertical resolution in the Hadley Centre Climate Model upon the simulation of stratocumulus is investigated in experiments using single column (SCM) and general circulation (GCM) model configurations. A threefold enhancement of vertical resolution in the boundary layer leads to improvements in the vertical structure of the cloud-topped boundary layer produced by the SCM and GCM in both well-mixed and decoupled situations. However, single and decoupled mixed layers in the marine stratocumulus subsidence regions are still too shallow and, despite increasing, layer cloud amounts remain generally too low. Moreover, closer examination of GCM data and SCM timeseries reveals an underlying sensitivity to vertical resolution in model interactions between boundary layer and convection processes which appears unrealistic. Stratocumulus simulation is thus unlikely to improve significantly as a result of enhanced resolution alone and further work is being undertaken to improve the Hadley Centre model's boundary layer scheme and, in particular, its interaction with the convection scheme. Nevertheless, this study shows that the full benefit of an improved boundary layer scheme will not be realized if the boundary layer structure is constrained by the rather poor lower troposphere resolution of the standard 19-level climate model. Future Hadley Centre model versions will seek to combine the added flexibility of a better resolved structure with improvements to the subgrid boundary layer parametrizations."
"7401531398;7101712720;","Factors affecting the levels of hydrogen peroxide in rainwater",1999,"10.1016/S1352-2310(98)00239-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033120718&doi=10.1016%2fS1352-2310%2898%2900239-8&partnerID=40&md5=160cde00975c44cff9d69c2335700311","Measurements of hydrogen peroxide (H2O2) and several meteorological and chemical parameters were made for 34 min events which occurred in Miami, Florida between April, 1995 and October, 1996. The measured H2O2 concentrations ranged from 0.3 to 38.6 μM with an average concentration of 6.9 μM. A strong seasonal dependence for H2O2 concentrations was observed during this period, with highest concentrations in the summer and lower levels in the winter, which corresponds to the stronger solar radiation and higher vaporization of volatile organic compounds (VOCs) in the summer and fall, and the weaker sunlight and lower vaporization in the winter and spring. Measurements also showed a significant increase trend of H2O2 with increasing ambient rainwater temperature. Rains that were out from lower latitude were exposed to higher solar irradiation and contained relatively higher levels of H2O2 than those from the north. All these observations indicate that photochemical reactions that involved volatile organic compounds are the predominant source of H2O2 observed in rainwater. During several individual rainstorms, H2O2 concentration was found to increase as a function of time due to electrical storm activities. This finding suggests that lightning could be an important factor that determines the level of H2O2 during thunderstorms. Statistical data showed that the highest concentrations of H2O2 were observed only in rains containing low levels of nonsea-salt sulfate (NSS), nitrate and hydrogen ion. H2O2 concentrations in continental originated rains were much lower than marine originated ones, indicating that air pollutants in continental rains could significantly deplete the H2O2 concentration in atmospheric gas-phase, clouds and rainwater."
"7006592026;55169000100;8299300000;7402803216;","A seasonal cycle simulation over eastern Asia and its sensitivity to radiative transfer and surface processes",1999,"10.1029/1998JD200052","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608690&doi=10.1029%2f1998JD200052&partnerID=40&md5=15148c07a467355289ff784afaf8c357","A multiseasonal simulation over eastern Asia and its sensitivity to cloud radiation and surface processes is analyzed. The model used is the NCAR Regional Climate Model (RegCM), the period of simulation is 13 months in length, and the emphasis of the analysis is on surface climatology, monsoon circulations, cloudiness, surface solar radiation, and top of the atmosphere outgoing longwave radiation. The model reproduces the basic features of the seasonal evolution of east Asia climate, but it overpredicts the intensity of the mature phase of the eastern Asia monsoon. Surface solar radiation is comparable with observations, while outgoing longwave radiation is mostly underestimated. Different formulations of large-scale cloud-producing mechanisms are shown to significantly affect cloud profiles, the surface and top of the atmosphere radiation budgets, and as a consequence, the simulated surface climatology. Variations in surface characteristics affect precipitation simulation in different ways during the cold/dry and warm/wet seasons. This paper emphasizes the importance of examining cloud radiation processes in regional climate models in greater detail than has been done in past studies. Copyright 1999 by the American Geophysical Union."
"7402584913;7202162685;7102636922;9038337500;","Modeling clouds and radiation for the November 1997 period of SHEBA using a column climate model",1999,"10.1029/98JD02517","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608668&doi=10.1029%2f98JD02517&partnerID=40&md5=741a5f6d7ec950dcb7f695418da2a8f7","A column version of the Arctic regional climate system model (ARCSYM) has been developed for testing general circulation model parameterizations in the Arctic. The ARCSYM column model has been employed for a 23-day period in November to simulate conditions over a multiyear ice floe that has been the site of intensive observations as part of the Surface Heat Budget of the Arctic (SHEBA) project. The large-scale tendencies of temperature, moisture, and wind are specified with values obtained from a special column data set obtained from the European Centre for Medium-Range Weather Forecasting. Comparisons between the ARCSYM column simulations and SHEBA data reveal that modeled temperature profiles are too cold aloft and generally too warm in the boundary layer. The occurrence of low clouds is severely underpredicted while the high cloud fraction is over predicted. The modeled longwave radiative cooling at the surface is 1.5-3 times as large as that observed. Much of this bias is related to problems with the treatment of clear-sky radiative transfer and in the simulated cloud optical properties. At the same time, the magnitude of modeled downward sensible heat flux at the surface is much too large. This has been related, in part, to the method for scaling temperature at the lowest modeled level to its surface air value under conditions of strong static stability. The importance of properly treating longwave radiative transfer under extremely cold, clear-sky conditions is evident in the sensitivity studies. The best simulation of cloud properties was achieved by assuming liquid cloud processes and properties at temperatures above 255 K. This temperature is significantly colder than that used in many climate models. The occurrence of supercooled clouds in the simulation dramatically reduced longwave cooling at the surface due to increases in the optical depth and fractional coverage of clouds. Results from a coupled sea ice-atmosphere simulation reveal that improvements in the atmospheric parameterizations are enhanced when the system is coupled. Copyright 1999 by the American Geophysical Union."
"7406354393;7005087624;35550043200;","Seasonal variations of upper tropospheric water vapor and high clouds observed from satellites",1999,"10.1029/1998JD200124","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608689&doi=10.1029%2f1998JD200124&partnerID=40&md5=9af7bec66e6e9449d0881863859a1dba","Multiyear satellite measurements of specific humidity at 215 mbar from the Microwave Limb Sounder aboard the Upper Atmosphere Research Satellite and cloud amount from the International Satellite Cloud Climatology Project have been used to investigate seasonal variations of upper tropospheric water vapor (UTWV), high clouds, and deep convection. The tropical and extratropical UTWV for each hemisphere have maximum values in summer and minimum values in winter because of the moistening effect of the tropical deep convection. The seasonal change of high cloud amount is similar to UTWV in the tropics but very different in the extratropics. Implications of the present results for the water vapor feedback in the climate system are discussed. Copyright 1999 by the American Geophysical Union."
"55802246600;7006592026;","Interactive coupling of regional climate and sulfate aerosol models over eastern Asia",1999,"10.1029/98JD02347","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608679&doi=10.1029%2f98JD02347&partnerID=40&md5=77f080006be9d0f586e91a3a793bc6d7","The NCAR regional climate model (RegCM) is interactively coupled to a simple radiatively active sulfate aerosol model over eastern Asia. Both direct and indirect aerosol effects are represented. The coupled model system is tested for two simulation periods, November 1994 and July 1995, with aerosol sources representative of present-day anthropogenic sulfur emissions. The model sensitivity to the intensity of the aerosol source is also studied. The main conclusions from our work are as follows: (1) The aerosol distribution and cycling processes show substantial regional spatial variability, and temporal variability varying on a range of scales, from the diurnal scale of boundary layer and cumulus cloud evolution to the 3-10 day scale of synoptic scale events and the interseasonal scale of general circulation features; (2) both direct and indirect aerosol forcings have regional effects on surface climate; (3) the regional climate response to the aerosol forcing is highly nonlinear, especially during the summer, due to the interactions with cloud and precipitation processes; (4) in our simulations the role of the aerosol indirect effects is dominant over that of direct effects; (5) aerosol-induced feedback processes can affect the aerosol burdens at the subregional scale. This work constitutes the first step in a long term research project aimed at coupling a hierarchy of chemistry/aerosol models to the RegCM over the eastern Asia region. Copyright 1999 by the American Geophysical Union."
"7102636922;7005557215;7007033191;8394332900;","Impact of tundra ecosystems on the surface energy budget and climate of Alaska",1999,"10.1029/98JD02798","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608671&doi=10.1029%2f98JD02798&partnerID=40&md5=3f10790a70736c30a14c4c4311c767a3","The sensitivity of regional terrestrial climate to the characteristics of tundra ecosystems has been investigated by a series of sensitivity experiments concentrating on the summer of 1995. Validation of the NCAR Land Surface Model and the Arctic Regional Climate System Model for this season indicate their adequacy for this study. Comparisons of the simulated climate in response to a wet meadow tundra or a dry heath tundra results in an expected cooling and moistening of both the local area and the adjoining sea ice and forested regions. The impact of atmospheric cloud-radiation feedbacks is to reduce the cooling as the summer progresses, although moistening continues, associated with increased precipitation in some areas. The spatial variability of the response is dependent upon prevailing synoptic conditions, which act to enhance moisture advection in certain areas. This study indicates that vegetation variation within the Arctic has substantial climatic effects that extend beyond the Arctic. In addition, the perturbations in the summer season could have profound implications of Arctic wintertime climate and issues of snow-albedo feedback and spring melt. Copyright 1999 by the American Geophysical Union."
"55205365700;7006738324;","Cumulus Cloud Formulations for Longwave Radiation Calculations",1999,"10.1175/1520-0469(1999)056<0837:CCFFLR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0344241108&doi=10.1175%2f1520-0469%281999%29056%3c0837%3aCCFFLR%3e2.0.CO%3b2&partnerID=40&md5=c69c9e5522ed856f475e957a9df45311","Longwave radiative transfer under broken cloud conditions is often treated as a problem in cloud bulk geometry, especially for cumulus clouds, because individual clouds are nearly black. However, climate models ignore cloud geometry and estimate the effects of broken cumulus clouds as the cloud amount weighted average of clear and black cloud overcast conditions (i.e., the black plate approximation). To overcome the simplicity of the black plate approximation, the authors developed a more generalized form of cloud geometrical effects on the effective cloud fraction. Following previous work, this form includes parameters that allow a more precise specification of cloud size and spatial distributions. The sensitivity of the generalized form to the variation in cloud size and spatial distributions is discussed in relation to others. Model calculations show that cloud bulk geometrical shapes, aspect ratio, size distribution, and side inclination angle are the primary factors significantly affecting the effective cloud fraction. These parameters are important at all cloud amounts with greatest sensitivity when the cloud amount is between 0.2 and 0.8. On the other hand, cloud spatial distributions do not significantly influence the effective cloud fraction when absolute cloud amount is less than 0.2 and/or when the cloud aspect ratio is less than 0.5. However, in the range of greatest sensitivity with large aspect ratio and absolute amount, model comparisons show large intermodel differences. The model discussed herein is cloud size dependent and applies most directly to small cumulus clouds (i.e., clouds small compared to the area under consideration)."
"7004047498;6602693652;7006595513;7006415284;7006235542;7006377579;","Climate-relevant modification of the aerosol size distribution by processes associated with orographic clouds",1999,"10.1016/S0169-8095(98)00106-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033393748&doi=10.1016%2fS0169-8095%2898%2900106-9&partnerID=40&md5=4c5d4a24dc320a2f91d2f21ea9d8f5fa","Cloud processes can modify optical properties of aerosol particles. As aerosols have been recognized to play an important role in the earth's radiation budget, the understanding of climate changes is also linked to cloud processes. During a field experiment at Great Dun Fell, Northern England in 1995, experimental evidence was found for the processing of aerosol by orographic clouds. During two periods (March 31, and April 3, 1995), a shift in the particle size distribution was detected when comparing data from upwind and downwind stations. For two periods of 1 and 3 h, when the shift was pronounced, the mass increase due to cloud processing was estimated to be 1.2 μg m-3 (±20%) and 1.7 μg m-3 (±50%). This equals roughly a quarter to the pre-existing submicron aerosol mass. As a major source of particulate matter, liquid-phase oxidation of sulphur dioxide was identified. Modelling results from Bradbury et al. [Bradbury, C., Bower, K.N., Choularton, T.W., Swietlicki, E., Birmili, W., Wiedensohler, A., Yuskiewicz, B., Berner, A., Dusek, U., Dore, C.-J., McFayden, G.G., 1999. Modelling of aerosol modification resulting from passage through a hill cap cloud.] strongly support such a reaction mechanism. Furthermore, large amounts of ultrafine particles were observed downwind the mountain ridge with almost none present at the upwind and summit sites. Some observations suggest that HCl may have degassed from the droplets when the cloud was evaporating. Another factor increasing the nucleation probability could have been the aerosol surface area which decreased by 35% prior to the occurrence of ultrafine particles."
"7006377579;7006235542;57195257572;7004191948;7004239300;57192265747;7003432387;7003566416;7005287667;7101751527;6603577857;56251307100;7405551904;24545697300;7202968142;55883059300;7003792988;7004047498;6602693652;7006595513;7006415284;7005174340;35477504600;6603655349;6602391997;6504094683;6602128405;7006671428;8140555300;6603003218;7006775179;6603332554;","The Great Dun Fell experiment 1995: An overview",1999,"10.1016/S0169-8095(98)00103-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0342770292&doi=10.1016%2fS0169-8095%2898%2900103-3&partnerID=40&md5=b3b0522cf40fe8ae9e9ef43b3e4aa2e0","During March and April of 1995 a major international field project was conducted at the UMIST field station site on Great Dun Fell in Cumbria, Northern England. The hill cap cloud which frequently envelopes this site was used as a natural flow through reactor to examine the sensitivity of the cloud microphysics to the aerosol entering the cloud and also to investigate the effects of the cloud in changing the aerosol size distribution, chemical composition and associated optical properties. To investigate these processes, detailed measurements of the cloud water chemistry (including the chemistry of sulphur compounds, organic and inorganic oxidised nitrogen and ammonia), cloud microphysics and properties of the aerosol and trace gas concentrations upwind and downwind of the cap cloud were undertaken. It was found that the cloud droplet number was generally strongly correlated to aerosol number concentration, with up to 2000 activated droplets cm-3 being observed in the most polluted conditions. In such conditions it was inferred that hygroscopic organic compounds were important in the activation process. Often, the size distribution of the aerosol was substantially modified by the cloud processing, largely due to the aqueous phase oxidation of S(IV) to sulphate by hydrogen peroxide, but also through the uptake and fixing of gas phase nitric acid as nitrate, increasing the calculated optical scattering of the aerosol substantially (by up to 24%). New particle formation was also observed in the ultrafine aerosol mode (at about 5 nm) downwind of the cap cloud, particularly in conditions of low total aerosol surface area and in the presence of ammonia and HCl gases. This was seen to occur at night as well as during the day via a mechanism which is not yet understood. The implications of these results for parameterising aerosol growth in Global Climate Models are explored."
"7003566416;56251307100;6603577857;7005287667;7101751527;7405551904;7006377579;7003432387;7004047498;7006415284;7005174340;7006595513;6602693652;","Droplet nucleation and growth in orographic clouds in relation to the aerosol population",1999,"10.1016/S0169-8095(98)00108-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6744227921&doi=10.1016%2fS0169-8095%2898%2900108-2&partnerID=40&md5=8095c7c67b900c48691d014f246bd22c","The formation and development of orographic clouds was studied in a field experiment comprising several measurement sites at a mountain ridge. The influence of the aerosol population present on the cloud microstructure was studied in relation to the dynamics in the cloud formation. Droplet nucleation scavenging was investigated by the introduction of a non-dimensional particle diameter related to the process, and it was found that the scavenging rose rapidly in a relatively narrow particle size interval. The size dependency of the scavenging could partly be explained by external mixture of the aerosol. The large particles in the cloud interstitial aerosol was found to be of a chemical nature which allows for only a very weak uptake of water, implying that the chemical composition of these particles rather than entrainment of dry air prevented the droplet nucleation. The aerosol particle number concentration was found to strongly influence the cloud microstructure. Droplet number concentrations up to approximately 2000 cm-3 were observed together with a substantially reduced effective droplet diameter. The observed effect of elevated particle number concentrations in orographic clouds was generalised to the climatologically more important stratiform clouds by the use of a cloud model. It was found that the microstructure of stratiform clouds was strongly dependent on the aerosol population present as well on the dynamics in the cloud formation."
"6601942466;56370372900;7005893321;","Scavenging ratios for sulfate, ammonium and nitrate determined at Mt. Sonnblick (3106 m a.s.l.)",1999,"10.1016/S1352-2310(98)00279-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033103026&doi=10.1016%2fS1352-2310%2898%2900279-9&partnerID=40&md5=b7c32570d728c72e08f00a90530740bc","For a time period of two years scavenging ratios were calculated for the high alpine site Mt. Sonnblick. Annual average values are 2.6 x 106, 1.4 x 106 and 1.8 x 106 for total nitrate, sulfate and ammonium, respectively, when the scavenging ratios are calculated based on overall monthly averages. Two other calculation methods (based on 'paired' monthly averages and on single days) are discussed in the paper. Higher scavenging ratios are observed for the beginning of the cold season (October-January) than for the summer months (June-September) the respective ratios being in the range of 3 to 5. Precipitation sulfate was found to be formed predominately by particulate sulfate (89-96%) while reactive gas-phase scavenging of sulfur dioxide is only of minor importance (4-11%). Precipitation nitrate on the other hand is predominantly formed by gas-phase scavenging of nitric acid (88-96%) and particulate nitrate contributes to a lesser extent (4-12%). The first estimate for ammonium in precipitation indicates that particulate ammonium accounts for 49-79%, while ammonia forms the remaining 51-21%. An equation was derived to interrelate the scavenging ratio of sulfate to the scavenging efficiency of particulate sulfate into cloud droplets. The comparison showed very satisfactory agreement in respect to the absolute values as well as to the annual variations."
"7005106543;","Parametrizations of global thermal emissions for simple climate models",1999,"10.1007/s003820050273","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032945404&doi=10.1007%2fs003820050273&partnerID=40&md5=06a9a9d6e8338b59057657b45773c165","A new, observationally based, parametrization of the thermal emissions by the Earth-atmosphere system for use in simple climate models is presented and discussed. The parametrization, allowing for the modelling of outgoing longwave fluxes in both clear and cloudy sky conditions, introduces temperature-dependent emissivities in a grey-body formulation, whose expressions are based on data from by the International Satellite Cloud Climatology Program (ISCCP). The proposed parametrization is compared to traditional ones and is used in a simple energy-balance model. It is shown how, unlike the traditional parametrizations, the proposed one correctly reproduces the runaway greenhouse phenomenon, i.e. the impossibility of an equilibrium for values of the solar constant larger than a critical one, which is known to occur in more complex radiative-convective models. It is also seen that the new parametrization induces the existence of a varying number of equilibria, depending on the value of the solar forcing, in agreement with previous studies. Further, the new parametrization is used to explore the effects of clouds on the Earth-atmosphere energy balance. It is found that for certain values of the model parameters the radiative effect of clouds might be either net cooling or net warming, depending on the magnitude of the solar forcing."
"7004154240;","On the effects of different flooding stages of the Oder and different land-use types on the distributions of evapotranspiration, cloudiness and rainfall in the Brandenburg-Polish border area",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345104348&partnerID=40&md5=099338e73d218a6708884bdace951dc8","Simulations of a typical summer day were performed with a non-hydrostatic meteorological model to examine the impact of natural (flooding) and anthropogenic land-surface changes (drainage of marshes and water meadows) on the local atmospheric water cycle. The results indicate that the changed hydrologic, thermal and dynamical conditions associated with different flooding stages or marshes may noticeably affect stability, the water supply to the atmosphere, cloud and precipitation microphysics. The magnitude and the kind of atmospheric response to the surface changes depend on the horizontal size of the converted patch and the kind of land-surface conversion. Cloudiness, for instance, may be reduced downwind of small flooded areas due to stabilization, while it may be increased downwind of large flooded areas due to the modification of the moisture convergence. The findings of this study suggest that, during extreme flooding events, the local weather forecasts have to consider the modified surface conditions."
"7101785401;7801421469;7102296517;6603929869;7004227345;7103158914;","Decadal climate variability in Australia during the twentieth century",1999,"10.1002/(SICI)1097-0088(199902)19:2<169::AID-JOC356>3.0.CO;2-Y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032942688&doi=10.1002%2f%28SICI%291097-0088%28199902%2919%3a2%3c169%3a%3aAID-JOC356%3e3.0.CO%3b2-Y&partnerID=40&md5=95ce4637269c0c42fa715ce6fba02269","High quality rainfall and surface temperature records for Australia during the period 1910-1993 are examined to quantify the relative importance of decadal variability and to ascertain if there is any relationship with sea-surface temperature (SST) variability over adjacent oceans on the same time scale. The decadal signal was estimated by low-pass filtering detrended annual averages of gridded data covering the entire continent to eliminate all spectral contributions with periods less than or equal to 8 years. Such variability typically accounts for 10-60% of the total variance. Low-pass filtering does not appear to affect the structure of the leading empirical orthogonal functions (EOFs) of rainfall and temperature, and the variability of all-Australia averages of these quantities are reasonably well-modeled as red noise, for which there is no preference for decadal time scales. Decadal variability in Indian Ocean SST south of 40°S is associated with rainfall variability over eastern Australia. A tendency for increased Tasman Sea SST (south of 15°S) to coincide with the above normal central and eastern Australian rainfall on both interannual and decadal time scales is also evident. The first EOF of interannual Pacific SST is associated with rainfall variability over Australia. This is not surprising as the EOF has an amplitude that tends to be out of phase with the Southern Oscillation Index (SOI). A similar relationship exists between the EOF of decadal SST variability and decadal fluctuations in both rainfall and the SOI. The first EOF of decadal Pacific SST has a broad spatial structure extending into the North and South Pacific. It has a time coefficient that is well-represented by the decadal component of the (northern) winter-time SST EOF produced in a separate study, which is available back to the turn of the century. When the decadal SST EOF warms the central Pacific, Australian rainfall is reduced, and both the daily maximum temperature and the diurnal temperature range over Australia are increased. These changes are consistent with radiative and evaporative changes associated with fluctuations in rainfall, cloud cover and soil moisture."
"7102300549;57203260116;","Gas-to-particle conversion in the atmosphere: I. Evidence from empirical atmospheric aerosols",1999,"10.1016/S1352-2310(98)00264-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033081417&doi=10.1016%2fS1352-2310%2898%2900264-7&partnerID=40&md5=c01fe5199cef62a7e76c41818cc03a0c","Condensable vapours such as sulphuric acid form aerosol in the atmosphere by the competing mechanisms of condensation on existing aerosol and the nucleation of new aerosol. Observational and theoretical evidence for the relative magnitudes of the competing processes is reviewed, and a number of general conclusions are made. Condensation is sensitive to the sticking probability of sulphuric acid molecules on aerosol particles, but there is now good evidence that it should be close to unity. In this case, equilibration timescales between acid vapour and the aerosol in most of the atmosphere are of the order of minutes or less, so that the acid concentration on such timescales given simply by the production rate times the equilibration time. When the acid concentration exceeds a threshold, nucleation will occur. The atmospheric aerosol therefore follows a history of initial formation in a nucleation burst followed by growth and coagulation with final removal by precipitation. This leads to the inverse correlation between aerosol number concentration and mass concentration found by Clarke (1992. Journal of Atmospheric Chemistry 14, 479-488) in the free troposphere. Binary homogeneous nucleation of sulphuric acid/water droplets, for which various simplified rates are compared, may dominate in such regions, but other mechanisms are possible elsewhere. A detailed analysis is performed of the number concentrations, removal rates, and masses of the components of the different types of global aerosols proposed empirically by Jaenicke (1993. Tropospheric Aerosols, Aerosol-Cloud-Climate Interaction. Academic Press, New York). There is a striking correlation between number concentrations in the nucleation and accumulation modes; and the giant aerosol mode, which if it is present dominates the mass, has little effect on the gas-to-particle conversion process. The mass of the atmospheric aerosol is therefore uncorrelated with the magnitude of molecular aerosol removal by condensation."
"7801524147;6701550654;7801496228;6602938973;","Evaluation of operational ECMWF surface heat fluxes: Impact of parameterisation changes during 1986-1995",1999,"10.1016/S0924-7963(98)00055-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033041140&doi=10.1016%2fS0924-7963%2898%2900055-4&partnerID=40&md5=1177d0b5d64d26c1a16812bf2f0fd7d1","Monthly mean values of ocean surface fluxes produced at the European Centre for Medium-Range Weather Forecasts (ECMWF) between 1986 and 1995 are investigated. The variations in the fluxes over this 10-year period are clearly linked to changes introduced into the analysis and forecast system, and the present study aims at documenting and understanding the sensitivity of surface flux estimates to model parameterisations. Periods are identified when properties of the ECMWF analyses can be characterized and discussed an terms of their ability to provide a forcing function for ocean circulation models. ECMWF surface fluxes are found to exhibit a sufficiently coherent geophysical behaviour from 1986 to 1988 to be considered as representing a climate state, in spite of several deficiencies characterized by weak solar and latent heat fluxes in equatorial regions. Globally, the annual mean and the seasonal cycle agree fairly well with recent observation-based climatologies. Several changes made to the model's physical parameterisations in the 1989-1991 period had a dramatic impact on the radiative fluxes. Net surface shortwave radiation were obviously over-estimated by up to 40 W m-2, and the net heat flux was clearly far from the expected geophysical values. During the 1992-1994 period, additional modifications to the radiation parameterisation scheme brought back solar radiation to a more reasonable level. However, the net input of heat in equatorial oceans appears to be low, and the uptake of heat by evaporation is insufficient at mid-latitudes in the southern hemisphere, a deficiency noticed in ECMWF analyses since the changes in cloud and radiation parameterisations of 1989. ECMWF latent and radiative fluxes show significant improvements in 1995 after the introduction of prognostic clouds in early April. This new parameterisation increases and adjusts the value of the latent heat loss at mid-latitudes in the southern hemisphere. The latent heat flux is found to be globally larger than in recent climatologies derived from ship observations. Regional deficiencies remain in the high northern latitudes (input of heat too great) and in narrow tropical bands in the inter-tropical convergence zone (ITCZ) (cooling by evaporation too great and solar heating too small), and produce a significant bias in the meridional heat transport. Over the 10-year period, latent heat loss is increased through almost 40 W m-2 by the successive model changes, apparently in the right direction, although it might be too large at the end of the period. In preparation for a study of the freshwater flux at the ocean surface (evaporation minus precipitation) in a forthcoming paper by Beranger et al. [Beranger, K., Siefridt, L., Barnier, B., Garnier, E., Roquet, H., 1998. Evaluation of operational ECMWF surface freshwater fluxes over oceans during 1991-97, and possible thermohaline effects. Submitted to J. Mar. Systems], this paper studies the climatological average of the latent heat flux over the period 1991-95. This average is characterized by a larger loss than in previous years (late 1980s), which appears to be more consistent with the current opinion that most climatologies derived from observations made by the Voluntary Observing Ship (VOS) program underestimate this type of exchange. However, the averaging does not fully correct the low evaporation at southern mid-latitudes. To conclude, the paper contributes to understanding of the accuracy currently reached in flux calculations at the global scale in the ECMWF reanalysis project."
"35232873900;7006417494;","Cirrus detrainment-temperature feedback",1999,"10.1029/1999GL900219","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033134085&doi=10.1029%2f1999GL900219&partnerID=40&md5=619a547fdaa00c2344502c9cb32d0e18","In considering the role of cirriform clouds in climate change, it is important to distinguish among the relationships of different high cloud types to large-scale atmospheric dynamics. While cirrostratus and cirrocumulus (CsCc) have a clear relation to deep convective sources, the ensemble behavior of cirrus is more subtle. An empirical relation is found between cirrus fraction and deep cloud top temperature that points to detrainment temperature as a dominant factor governing tropical and subtropical cirrus. This cirrus-detrainment-temperature (CDT) relation provides a target for modelers, and suggests an additional cloud-climate feedback. As surface temperatures warm, detrainment temperatures cool as deep cloud top height increases. The CDT relation Implies that cirrus fraction increases. Because cirrus are optically thinner than CsCc, the competition between longwave feedbacks and cloud albedo feedbacks leads to a hypothesized positive climate feedback by cirrus fraction. Copyright 1999 by the American Geophysical Union."
"6603809220;","Climate sensitivity of the CSIRO GCM: Effect of cloud modeling assumptions",1999,"10.1175/1520-0442(1999)012<0334:CSOTCG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033079618&doi=10.1175%2f1520-0442%281999%29012%3c0334%3aCSOTCG%3e2.0.CO%3b2&partnerID=40&md5=b3c00b150115bb78a20d3c19dcb4e398","The climate sensitivity of the CSIRO Global Climate Model is investigated using uniform sea surface temperature perturbation experiments. One experiment (denoted DIAG) uses a diagnostic treatment of clouds, with fixed cloud radiative properties that vary with height. The other experiment (denoted CTRL) uses a recently introduced prognostic treatment of stratiform clouds, with interactive calculation of cloud radiative properties. The DIAG experiment has a positive shortwave (SW) cloud feedback and a negative longwave (LW) feedback, due to an overall reduction of midlevel and high cloudiness in the warmer climate. The signs of both the SW and LW feedbacks are opposite in the CTRL experiment due to an overall increase of cloud water content in the warmer climate. Because of cancellation between the SW and LW components, there is not a large difference in the net cloud feedback between the two experiments, with both having a modest negative cloud feedback, as measured by the change in cloud radiative forcing. The CTRL experiment has a larger clear-sky climate sensitivity than the DIAG experiment. Off-line radiative calculations are used to show that this is primarily because of a stronger water vapor feedback. This is caused by differences in upper-tropospheric cloud radiative forcing that give a stronger upward shift of the tropopause on warming when the prognostic scheme is used. A sensitivity test shows that an artificial restriction on the maximum height of high clouds that exists in the diagnostic scheme is the reason for the different behavior. The robustness of the result obtained in the CTRL experiment is investigated via 18 perturbation experiments, in which key parameters in the prognostic cloud scheme are varied, while retaining the overall approach used in the CTRL experiment. As far as possible, theory and observations are used to constrain the ranges within which these parameters are varied. It is found that the behavior of the scheme under climate change is generally robust, with no statistically significant changes in LW cloud feedback and only modest changes in SW cloud feedback. Overall, larger differences (both in control climate and in climate sensitivity) result from parameter changes that effect cloud formation than from changes that affect precipitation processes or cloud radiative properties.The climate sensitivity of the CSIRO Global Climate Model is investigated using uniform sea surface temperature perturbation experiments. One experiment (denoted DIAG) uses a diagnostic treatment of clouds, with fixed cloud radiative properties that vary with height. The other experiment (denoted CTRL) uses a recently introduced prognostic treatment of stratiform clouds, with interactive calculation of cloud radiative properties. The DIAG experiment has a positive shortwave (SW) cloud feedback and a negative longwave (LW) feedback, due to an overall reduction of midlevel and high cloudiness in the warmer climate. The signs of both the SW and LW feedbacks are opposite in the CTRL experiment due to an overall increase of cloud water content in the warmer climate. Because of cancellation between the SW and LW components, there is not a large difference in the net cloud feedback between the two experiments, with both having a modest negative cloud feedback, as measured by the change in cloud radiative forcing. The CTRL experiment has a larger clear-sky climate sensitivity than the DIAG experiment. Off-line radiative calculations are used to show that this is primarily because of a stronger water vapor feedback. This is caused by differences in upper-tropospheric cloud radiative forcing that give a stronger upward shift of the tropopause on warming when the prognostic scheme is used. A sensitivity test shows that an artificial restriction on the maximum height of high clouds that exists in the diagnostic scheme is the reason for the different behavior. The robustness of the result obtained in the CTRL experiment is investigated via 18 perturbation experiments, in which key parameters in the prognostic cloud scheme are varied, while retaining the overall approach used in the CTRL experiment. As far as possible, theory and observations are used to constrain the ranges within which these parameters are varied. It is found that the behavior of the scheme under climate change is generally robust, with no statistically significant changes in LW cloud feedback and only modest changes in SW cloud feedback. Overall, larger differences (both in control climate and in climate sensitivity) result from parameter changes that affect cloud formation than from changes that affect precipitation processes or cloud radiative properties."
"7004764167;","Comparison of mechanisms of cloud-climate feedbacks in GCMs",1999,"10.1175/1520-0442(1999)012<1480:comocc>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032883626&doi=10.1175%2f1520-0442%281999%29012%3c1480%3acomocc%3e2.0.co%3b2&partnerID=40&md5=d79ecfbd9ee23ef20e01ace019f2fdd2","International model comparisons of cloud-climate feedbacks have typically been restricted to assessing only the radiative effect of changes in clouds and have not attempted to explain the mechanisms for differences in cloud feedbacks. This paper uses different versions of the U.K. Meteorological Office GCM run at the Hadley Centre to illustrate the usefulness of a detailed comparison of microphysical cloud properties in understanding cloud feedback mechanisms and their effect on the regional distribution of the predicted warming in simulations of climate change. The inclusion of interactive cloud radiative properties explains much of the difference in the spatial patterns of cloud feedback and leads to a marked difference in the response of the large-scale circulation and in the resulting meridional gradient of surface temperature changes. In the model versions that include interactive radiative properties, the strength of the related feedback is determined by the water path of the cloud in the control experiment. Difficulties in performing such a detailed comparison on a wider range of models may arise from the lack of diagnostics in a common format being available from different models and because of the range of assumptions about how clouds are treated by different radiation schemes. A suggestion is put forward for a possible common format that would enable comparison of such diagnostics."
"7403318365;57193132723;","Effects of cloud parameterization on the simulation of climate changes in the GISS GCM",1999,"10.1175/1520-0442(1999)012<0761:eocpot>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033102334&doi=10.1175%2f1520-0442%281999%29012%3c0761%3aeocpot%3e2.0.co%3b2&partnerID=40&md5=ac444882946b07ffd277b3b8147611a3","Climate changes obtained from five doubled CO2 experiments with different parameterizations of large-scale clouds and moist convection are studied by use of the Goddard Institute for Space Studies (GISS) GCM at 4° lat × 5° long resolution. The baseline for the experiments is GISS Model II, which uses a diagnostic cloud scheme with fixed optical properties and a convection scheme with fixed cumulus mass fluxes and no downdrafts. The global and annual mean surface air temperature change (ΔTs) of 4.2°C obtained by Hansen et al. using the Model II physics at 8° lat × 10° long resolution is reduced to 3.55°C at the finer resolution. This is due to a significant reduction of tropical cirrus clouds in the warmer climate when a finer resolution is used, despite the fact that the relative humidity increases there with a doubling of CO2. When the new moist convection parameterization of Del Genio and Yao and prognostic large-scale cloud parameterization of Del Genio et al. are used, ΔTs is reduced to 3.09°C from 3.55°C. This is the net result of the inclusion of the feedback of cloud optical thickness and phase change of cloud water, and the presence of areally extensive cumulus anvil clouds. Without the optical thickness feedback, ΔTs is further reduced to 2.74°C, suggesting that this feedback is positive overall. Without anvil clouds, ΔTs is increased from 3.09° to 3.7°C, suggesting that anvil clouds of large optical thickness reduce the climate sensitivity. The net effect of using the new large-scale cloud parameterization without including the detrainment of convective cloud water is a slight increase of ΔT, from 3.56° to 3.7°C. The net effect of using the new moist convection parameterization without anvil clouds is insignificant (from 3.55° to 3.56°C). However, this is a result of a combination of many competing differences in other climate parameters. Despite the global cloud cover decrease simulated in most of the experiments, middle- and high-latitude continental cloudiness generally increases with warming, consistent with the sense of observed twentieth-century cloudiness trends; an indirect aerosol effect may therefore not be the sole explanation of these observations. An analysis of climate sensitivity and changes in cloud radiative forcing (CRF) indicates that the cloud feedback is positive overall in all experiments except the one using the new moist convection and large-scale cloud parameterization with prescribed cloud optical thickness, for which the cloud feedback is nearly neutral. Differences in ΔCRF among the different experiments cannot reliably be anticipated by the analogous differences in current climate CRF. The meridional distribution of ΔCRF suggests that the cloud feedback is positive mostly in the low and midlatitudes, but in the high latitudes, the cloud feedback is mostly negative and the amplification of ΔTs is due to other processes, such as snow/ice-albedo feedback and changes in the lapse rate. The authors' results suggest that when a sufficiently large variety of cloud feedback mechanisms are allowed for, significant cancellations between positive and negative feedbacks result, causing overall climate sensitivity to be less sensitive to uncertainties in poorly understood cloud physics. In particular, the positive low cloud optical thickness correlations with temperature observed in satellite data argue for a minimum climate sensitivity higher than the 1.5°C that is usually assumed."
"35461255500;","Atmospheric aerosols: global effects",1999,"10.1016/S0021-8502(99)80012-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033189655&doi=10.1016%2fS0021-8502%2899%2980012-3&partnerID=40&md5=eecdd4ead480200719695bfb070a9ef2","Atmospheric aerosols influence climate, directly through scattering and absorbing radiation and indirectly through modifying the optical properties and lifetime of clouds. To address the global effects of aerosols, it is important to know their diurnal and spatial variations of concentrations and compositions. In addition, their formation and growth mechanisms as well as the formation and growth of cloud droplets should be considered."
"24080547200;7005955015;","Shortwave cloud forcing of marine stratocumulus clouds",1999,"10.1016/S1464-1909(98)00042-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032835715&doi=10.1016%2fS1464-1909%2898%2900042-2&partnerID=40&md5=bc391deb1726b22d2138f34779f04e19","Shortwave cloud forcing (SWCF) is one measure of the impact of clouds on radiation and climate. This quantity is determined by insolation, surface albedo, cloud thickness and height, cloud cover and the size distribution of the cloud droplets. We have carried out controlled experiments with a single column model in order to facilitate interpretation of climate model predictions of cloud parameters and radiation budget components. For this purpose we have used the radiation code of NCAR CCM2. The sensitivity of SWCF to the above parameters is investigated for marine stratocumulus clouds. We find that clouds with low liquid water path (LWP) are most sensitive to a change in LWP whereas clouds with high LWP are most sensitive to a change in cloud cover. Both effective radius and latitude have a modest effect on the sensitivity. To check the validity of the results we have used measurements of SWCF and LWP taken between 20 and 30°N, and 120 and 130°W in July. The comparison of the shortwave cloud forcing shows that the model highly overestimates the monthly averaged forcing. We find that the overestimation can largely be explained by the combined effects of a fractal cloud structure, day-to-day variations in cloud cover and LWP, and the model's treatment of a partly cloudy sky."
"8204540500;7401823436;7405408411;","The climatic effects of biomass burning: Investigations with a global climate model",1999,"10.1016/S1364-8152(98)00077-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033059354&doi=10.1016%2fS1364-8152%2898%2900077-2&partnerID=40&md5=e1de07db4f81b502cd2162b4dc2d4f47","A global climate model, the National Center for Atmospheric Research (NCAR) Climate System Model (CSM), has been used to evaluate direct, indirect, and transport effects of the smoke from biomass burning. Biomass smoke distributions were estimated via a seasonally-varying source function that produced monthly mean estimates of the flux of trace gases to the atmosphere which were then confirmed qualitatively using satellite observations. The direct effect was modeled by assuming new cloud fractions wherever biomass smoke occurred. A sensitivity study was conducted to determine the most appropriate way to add these new 'clouds'. An indirect effect on existing clouds was modeled by reducing the cloud optical depth (which increases reflectivity) when they coincided with biomass smoke. Advection of the smoke has been accomplished by adding it as a tracer in the NCAR CCM3 (the atmospheric component of CSM). Preliminary results yield surface temperature reductions of several degrees and heating of the mid-levels of the atmosphere in the vicinity of major smoke emissions.A global climate model, the National Center for Atmospheric Research (NCAR) Climate System Model (CSM), has been used to evaluate direct, indirect, and transport effects of the smoke from biomass burning. Biomass smoke distributions were estimated via a seasonally-varying source function that produced monthly mean estimates of the flux of trace gases to the atmosphere which were then confirmed qualitatively using satellite observations. The direct effect was modeled by assuming new cloud fractions wherever biomass smoke occurred. A sensitivity study was conducted to determine the most appropriate way to add these new `clouds'. An indirect effect on existing clouds was modeled by reducing the cloud optical depth (which increases reflectivity) when they coincided with biomass smoke. Advection of the smoke has been accomplished by adding it as a tracer in the NCAR CCM3 (the atmospheric component of CSM). Preliminary results yield surface temperature reductions of several degrees and heating of the mid-levels of the atmosphere in the vicinity of major smoke emissions."
"56363371300;57193920163;7006346149;","Estimating the subgrid variance of saturation, and its parametrization for use in a GCM cloud scheme",1999,"10.1256/smsqj.56012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033427713&doi=10.1256%2fsmsqj.56012&partnerID=40&md5=d02cfecd481f0ab55b080b352c0a2bf6","The prediction of cloud fraction and condensate in the unified weather forecasting/climate prediction model of the UK Meteorological Office, and many other general-circulation models, depends upon a probability distribution of a saturation variable in a grid box. A method of estimating the width of the probability distribution of the saturation variable on the scales of one grid box of the climate configuration (2.5°latitude x 3.75°longitude) has been created, using analyses from the global weather forecasting configuration (0.55° latitude x 0.833°longitude). This width was found to be potentially very variable in time at many locations, therefore the use of climatological values was inappropriate. A parametrization was created to predict the width of the probability distribution of the saturation variable for use in the climate model. The concept of this empirical parametrization was based upon a scaling relationship often observed, and which is present in the global analyses. This new statistically based parametrization replaced the standard approximation used in the Hadley Centre climate model, and significantly reduced the model's biases concerning water vapour, temperature and cloud amount in the upper troposphere."
"35116696600;35511427300;","Sensitivity of a cloud parameterization package in the National Center for Atmospheric Research Community Climate Model",1999,"10.1029/1999JD900079","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17744406950&doi=10.1029%2f1999JD900079&partnerID=40&md5=3f526fd27521c04558210fbe44b8c970","A physically based cloud parameterization package, which includes the Arakawa-Schubert (AS) scheme for subgrid-scale convective clouds and the Sundqvist (SUN) scheme for nonconvective grid-scale layered clouds (hereafter referred to as the SUNAS cloud package), is incorporated into the National Center for Atmospheric Research (NCAR) Community Climate Model, Version 2 (CCM2). The AS scheme is used for a more reasonable heating distribution due to convective clouds and their associated precipitation. The SUN scheme allows for the prognostic computation of cloud water so that the cloud optical properties are more physically determined for shortwave and longwave radiation calculations. In addition, the formation of anvil-like clouds from deep convective systems is able to be simulated with the SUNAS package. A 10-year simulation spanning the period from 1980 to 1989 is conducted, and the effect of the cloud package on the January climate is assessed by comparing it with various available data sets and the National Center for Environmental Protection/NCAR reanalysis. Strengths and deficiencies of both the SUN and AS methods are identified and discussed. The AS scheme improves some aspects of the model dynamics and precipitation, especially with respect to the Pacific North America (PNA) pattern. CCM2's tendency to produce a westward bias of the 500 mbar stationary wave (time-averaged zonal anomalies) in the PNA sector is remedied apparently because of a less ""locked-in"" heating pattern in the tropics. The additional degree of freedom added by the prognostic calculation of cloud water in the SUN scheme produces interesting results in the modeled cloud and radiation fields compared with data. In general, too little cloud water forms in the tropics, while excessive cloud cover and cloud liquid water are simulated in midlatitudes. This results in a somewhat degraded simulation of the radiation budget. The overall simulated precipitation by the SUNAS package is, however, substantially improved over the original CCM2. Copyright 1999 by the American Geophysical Union."
"7004303248;7102959401;11440642000;","Radiance covariance and climate models",1999,"10.1175/1520-0442(1999)012<1409:rcacm>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032863695&doi=10.1175%2f1520-0442%281999%29012%3c1409%3arcacm%3e2.0.co%3b2&partnerID=40&md5=9c8239fdfc9180a3f86da5c6d08b208e","Spectral empirical orthogonal functions (EOFs) derived from the covariance of satellite radiance spectra may be interpreted in terms of the vertical distribution of the covariance of temperature, water vapor, and clouds. This has been done for four major geographic regions: the tropical oceans, midlatitude oceans, and three important land areas. The purpose of the investigation is to demonstrate the important constraints that resolved spectral radiances can place upon climate models."
"6603227225;35601572600;6603753477;57203233100;","A methodology for measuring cirrus cloud visible-to-infrared spectral optical depth ratios",1999,"10.1175/1520-0426(1999)016<0251:AMFMCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032732430&doi=10.1175%2f1520-0426%281999%29016%3c0251%3aAMFMCC%3e2.0.CO%3b2&partnerID=40&md5=cafaebc96ec523d23e1ea1b230f4a9bf","Knowledge of cirrus cloud optical depths is necessary to understand the earth's current climate and to model the cloud radiation impact on future climate. Cirrus clouds, depending on the ratio of their shortwave 'visible' to longwave 'infrared' optical depth, can act to either cool or warm the planet. In this study, visible-to-infrared cirrus cloud optical depth ratios were measured using ground-based lidar and Fourier transform spectrometry. A radiosonde temperature profile combined with the 0.532-μm-high spectral resolution lidar vertical cloud optical depth profile provided an effective weighting to the cloud radiance measured by the interferometer. This allowed evaluation of cirrus cloud optical depths in 18 infrared microwindows between water vapor absorption lines within the 800-1200-cm-1 infrared atmospheric window. The data analysis was performed near the peak solar and terrestrial emission regions, which represent the effective radiative cloud forcing efficiency of the given cloud sample. Results are also presented that demonstrate the measurement of infrared optical depth using an assumed uniform cloud extinction cross section, which requires generic lidar cloud boundary data. The measured cloud extinction profile provided a more robust solution that would allow analysis of multiple-layer clouds and removed the uniform cloud extinction cross-section assumption. Mie calculations for ice particles were used to generate visible and infrared extinction coefficients; these were compared against the measured visible-to-infrared optical depth ratios. The results demonstrate strong particle size and shape sensitivity across the infrared atmospheric window."
"6602639271;7005070958;57203049963;","Regional cloud cover change associated with global climate change: Case studies for three regions of the United States",1999,"10.1175/1520-0442(1999)012<2128:RCCCAW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032754494&doi=10.1175%2f1520-0442%281999%29012%3c2128%3aRCCCAW%3e2.0.CO%3b2&partnerID=40&md5=2fa326fdfc143a9c72239fe9a707ed02","Land-based observations of cloud cover, for the period 1900-87 and averaged over three geographical regions of the United States (coastal southwest, coastal northeast, and southern plains), show strong positive correlations with one estimate of global mean surface temperature, a finding consistent with prior investigations that suggest cloud cover over land has increased during global warm periods relative to cold periods. It is also found that the strengths of three permanent high/low pressure systems (North Pacific high, Icelandic low, and Azores high) are negatively correlated with global mean surface temperature, suggesting a possible connection between regional cloud cover, for certain locations, and the strengths of adjacent high/low pressure systems. Specifically, for the regions considered it is suggested that the coastal southwest cloud cover is related to changes in the strength of the subtropical North Pacific high, that for the southern plains also to the strength of the North Pacific high, and that for the coastal northeast to the strength of the Icelandic low. Thus the climate-induced change in cloud cover for certain regions appears related, at least in part, to climate-induced change in the strengths of adjacent high/low pressure systems, and plausible physical explanations for this relation are provided for the three regions that have been studied. This does not, of course, provide a direct physical cause-and-effect explanation for the changes in regional cloud cover, because the mechanisms that cause the intensities of the high/low pressure systems to change are not understood.Land-based observations of cloud cover, for the period 1900-87 and averaged over three geographical regions of the United States (coastal southwest, coastal northeast, and southern plains), show strong positive correlations with one estimate of global mean surface temperature, a finding consistent with prior investigations that suggest cloud cover over land has increased during global warm periods relative to cold periods. It is also found that the strengths of three permanent high/low pressure systems (North Pacific high, Icelandic low, and Azores high) are negatively correlated with global mean surface temperature, suggesting a possible connection between regional cloud cover, for certain locations, and the strengths of adjacent high/low pressure systems. Specifically, for the regions considered it is suggested that the coastal southwest cloud cover is related to changes in the strength of the subtropical North Pacific high, that for the southern plains also to the strength of the North Pacific high, and that for the coastal northeast to the strength of the Icelandic low. Thus the climate-induced change in cloud cover for certain regions appears related, at least in part, to climate-induced change in the strengths of adjacent high/low pressure systems, and plausible physical explanations for this relation are provided for the three regions that have been studied. This does not, of course, provide a direct physical cause-and-effect explanation for the changes in regional cloud cover, because the mechanisms that cause the intensities of the high/low pressure systems to change are not understood."
"7003960899;","Combined satellite- and surface-based observations of clouds",1999,"10.1175/1520-0442(1999)012<0897:csasbo>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033102227&doi=10.1175%2f1520-0442%281999%29012%3c0897%3acsasbo%3e2.0.co%3b2&partnerID=40&md5=65d85da8ad123e5ee564f0d81cb6893e","A new method for combining satellite and surface-based cloud observations into a self-consistent three-dimensional field is presented. This method derives the probabilities of the cloud states, which are most consistent with all of the observations and assumptions concerning the nature and relative uncertainties of the observations. It is applied to a three-layer atmosphere using monthly satellite-and surface-based cloud observations. The reconstructions of the observed fields usually lead to modifications of the surface-observed low cloud amount of less than 0.008 fractional cloud cover. Over the ocean the satellite-view low cloud amounts are usually decreased by between 0.06 and 0.12 for most of the middle latitudes and southeastern tropical Pacific. Over land the adjustments in the satellite low cloud amounts are generally smaller. The method leads to increases in satellite high cover of between 0.03 and 0.09 over most regions, and increases in middle cloud cover of up to around 0.03 over the subtropical oceans. Comparisons between derived total cloud cover and that calculated with the commonly used random and mixed overlap assumptions suggest that the mixed assumption generally better fits the results. On the whole there is overall fairly good agreement between the percent low cloud relative to total cloud cover in the reconstructed observations and a global climate model, but the model has a far larger percentage of high clouds nearly everywhere, especially in the tropical convective regions and over the Indian subcontinent."
"7006204393;7004449177;7005626683;7005807606;55740664200;","Cloud detection by radar and lidar at the arm cart sites",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032637074&partnerID=40&md5=f5e4acbf585805bfbd6c7ca4ce9e3b34","The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program operates highly-instrumented Cloud and Radiation Testbed (CART) sites in Oklahoma, Alaska, and the Tropical Western Pacific Ocean. A primary objective of ARM is to understand in detail how clouds affect atmospheric radiation transfer, and consequently climate. Based on several months of data from the CART site in Oklahoma, this report demonstrates how cloud detection by the micro-pulse lidar and the millimeter-wave radar compare."
"7006698304;","Cloud cover in the ECMWF reanalysis",1999,"10.1175/1520-0442(1999)012<0947:CCITER>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033117442&doi=10.1175%2f1520-0442%281999%29012%3c0947%3aCCITER%3e2.0.CO%3b2&partnerID=40&md5=6f9bbfd76851cae1cbffaf472af6618a","Data from reanalyses recently carried out by several climate and numerical weather prediction centers will find a variety of applications in different branches of atmospheric science. A careful evaluation of the many aspects of these datasets is a prerequisite for their successful use. This paper describes the implementation of a fully prognostic cloud scheme into the ECMWF reanalysis system and provides a first assessment of the simulation of cloud cover by comparing it with monthly mean cloud cover derived from satellite observations in the context of the International Satellite Cloud Climatology Project for the years 1983-90. Special emphasis is put on the major cloud regimes and their intra- and interannual variation. The main deficiencies identified are an underestimation of extratropical cloud cover over the oceans by 10%-15%, an overestimation of trade wind cumulus cover by about 10%-15%, an underestimation of stratocumulus off the west coasts of the subtropical continents by 15%, and an underestimation of the summer maximum in cloud cover over the Eurasian continent. Despite these deficiencies it is shown that the reanalysis system is able to capture the main aspects of the interannual variability, especially those connected to the major El Nino events in the observation period.Data from reanalyses recently carried out by several climate and numerical weather prediction centers will find a variety of applications in different branches of atmospheric science. A careful evaluation of the many aspects of these datasets is a prerequisite for their successful use. This paper describes the implementation of a fully prognostic cloud scheme into the ECMWF reanalysis system and provides a first assessment of the simulation of cloud cover by comparing it with monthly mean cloud cover derived from satellite observations in the context of the International Satellite Cloud Climatology Project for the years 1983-90. Special emphasis is put on the major cloud regimes and their intra- and interannual variation. The main deficiencies identified are an underestimation of extratropical cloud cover over the oceans by 10%-15%, an overestimation of trade wind cumulus cover by about 10%-15%, an underestimation of stratocumulus off the west coasts of the subtropical continents by 15%, and an underestimation of the summer maximum in cloud cover over the Eurasian continent. Despite these deficiencies it is shown that the reanalysis system is able to capture the main aspects of the interannual variability, especially those connected to the major El Nino events in the observation period."
"14031906100;7403958574;","Calculation of Probability of Cloud-Free Lines-of-Sight at Given Heights in Foshan, China",1999,"10.1007/BF02973089","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347747982&doi=10.1007%2fBF02973089&partnerID=40&md5=98114e945ae2c807817cdeee4b5cd602","Based on Lund and Shanklin's work (1972), methods of calculating Probability of Cloud-Free Lines-of-Sight (PCFLOS), Persistence Probability of Cloud-Free Lines-of-Sight (PPCFLOS) and Recurrence Probability of Cloud-free Lines-of-Sight (RPCFLOS) at given heights are presented. PCFLOS, PPCFLOS and RPCFLOS are calculated in Foshan, China by conventional observation data from 1961 to 1990. The conclusions are: (1) The higher the elevations, the smaller the PCFLOS and the larger the view angles, the larger the PCFLOS. (2) PPCFLOS and RPCFLOS decrease with the increase of elevation and the delay of time. (3) RPCFLOS is always equal to or larger than PPCFLOS at lag times."
"7003536279;7003728829;7005956183;36785976300;","Investigations of cloud layer base and top heights from 95 GHz radar reflectivity data",1999,"10.1016/S1464-1909(98)00032-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032858551&doi=10.1016%2fS1464-1909%2898%2900032-X&partnerID=40&md5=e1d7a5d40eac571955f4eae54b8ab4d8","Cloud radars operating at millimeter wavelengths have proven to be invaluable for studying the 3-dimensional distribution of stratiform clouds. An improved knowledge of the occurrence of multiple cloud layers as well as of heights of their upper and lower boundaries is important for the determination of radiative fluxes with a higher accuracy. In this study measurements with the 95 GHz radar of GKSS Research Centre, Geesthacht, are used to determine base and top heights of layers of different cloud types. However, an accurate retrieval of cloud boundaries by remote sensors is not obvious, e.g., it is known that simultaneous measurements of the radar and backscatter lidars often show significant differences in cloud base heights. Reasons for inaccuracies in the determination of cloud boundary heights are discussed. Possibilities for corrections are illustrated that will finally lead to more reliable cloud boundary statistics necessary to improve radiative transfer calculations within large-scale weather forecasting and climate models."
"7005213997;7102552750;","Toward an explanation of the annual cycle of cloudiness over the Arctic Ocean",1999,"10.1175/1520-0442(1999)012<0395:TAEOTA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033080364&doi=10.1175%2f1520-0442%281999%29012%3c0395%3aTAEOTA%3e2.0.CO%3b2&partnerID=40&md5=cc4ac45174af375010bc81dbc05df255","The annual cycle of low cloud amount over the Arctic Ocean is examined using climatological data and a radiative-turbulent column model. Three hypotheses for the annual cycle are formulated, compared with climatological data for consistency, and then tested using the numerical model. The hypotheses identify three factors that might explain the difference in arctic low cloud amount between summer and winter: 1) the difference in surface specific humidity between the pack ice and the surrounding continents, 2) evaporation at the surface of the ice pack, and 3) the temperature-dependent formation and precipitation of atmospheric ice. Qualitatively, the hypotheses all appear to be consistent with available climatological data, except that the transition between the winter and summer cloudiness regimes occurs one month before the influx of atmospheric moisture increases from its wintertime level, which is inconsistent with the first hypothesis. The model, which includes a turbulence-closure cloud scheme and ice-phase microphysical processes, simulates the summer and winter cloud regimes when forced with the boundary conditions corresponding to those seasons. The model results suggest that the temperature dependence of ice-phase microphysical processes is an essential factor in explaining the annual cycle of low cloud amount. When the growth of atmospheric ice by vapor deposition is suppressed in the model, the winter case is as cloudy as the summer case. It is shown that, among general circulation models participating in the Atmospheric Model Intercomparison Project, those including ice microphysics produce more accurate simulations of the mean difference between summer and winter cloud amount over the Arctic Ocean than models without atmospheric ice processes. The results of this study suggest that the duration of the summertime cloudy season over the Arctic Ocean would be longer in a warmer climate and shorter in a cooler climate.The annual cycle of low cloud amount over the Arctic Ocean is examined using climatological data and a radiative-turbulent column model. Three hypotheses for the annual cycle are formulated, compared with climatological data for consistency, and then tested using the numerical model. The hypotheses identify three factors that might explain the difference in arctic low cloud amount between summer and winter: 1) the difference in surface specific humidity between the pack ice and the surrounding continents, 2) evaporation at the surface of the ice pack, and 3) the temperature-dependent formation and precipitation of atmospheric ice. Qualitatively, the hypotheses all appear to be consistent with available climatological data, except that the transition between the winter and summer cloudiness regimes occurs one month before the influx of atmospheric moisture increases from its wintertime level, which is inconsistent with the first hypothesis. The model, which includes a turbulence-closure cloud scheme and ice-phase microphysical processes, simulates the summer and winter cloud regimes when forced with the boundary conditions corresponding to those seasons. The model results suggest that the temperature dependence of ice-phase microphysical processes is an essential factor in explaining the annual cycle of low cloud amount. When the growth of atmospheric ice by vapor deposition is suppressed in the model, the winter case is as cloudy as the summer case. It is shown that, among general circulation models participating in the Atmospheric Model Intercomparison Project, those including ice microphysics produce more accurate simulations of the mean difference between summer and winter cloud amount over the Arctic Ocean than models without atmospheric ice processes. The results of this study suggest that the duration of the summertime cloudy season over the Arctic Ocean would be longer in a warmer climate and shorter in a cooler climate."
"6603431534;35473805400;7003921226;","Fair-weather cumuli studies with a 94 GHz Doppler radar",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032645253&partnerID=40&md5=f85d5e40639d6ad7934eed80be4e7660","A light weight, single-antenna 94 GHz radar was designed, constructed, tested and operated for the observation of clouds at the Rosenstiel School of the University of Miami. Some of the fair-weather cumulus observations made with the radar were analyzed. The excellent sensitivity and high temporal and spatial resolutions useful for a unique description of the in-cloud dynamics were demonstrated."
"7006530726;7401892219;","Radar-derived estimates of latent heating in the subtropics",1999,"10.1175/1520-0493(1999)127<0726:RDEOLH>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032741151&doi=10.1175%2f1520-0493%281999%29127%3c0726%3aRDEOLH%3e2.0.CO%3b2&partnerID=40&md5=8d4d8c09779ffa685cea4a0263012a5e","Atmospheric warming from cloud heating has a major affect on worldwide atmospheric circulations and climate. Studies have shown that the dominant source for cloud heating is the phase change of water. The location and magnitude of cloud heating has a substantial impact on atmospheric circulations. Therefore, identifying the location of phase changes provides information necessary for accurate modeling of atmospheric circulations and climate. Radar reflectivity is a signature predominantly produced from rain formed from condensation, the primary process that produces heating. Through the application of principal component analysis on a nonhydrostatic cloud model, heating, and derived reflectivity data, a technique to illustrate a future heating algorithm capable of estimating cloud heating from reflectivity data is examined. Formative, intensifying, and mature stages of a Convection and Precipitation Electrification Experiment squall-type convective system were used to demonstrate these results. The accuracy of the technique's estimates for the mean convective and stratiform profiles to within 1.0 K h-1 on average throughout the vertical column shows the merit of this statistical technique. The use of this type of technique in conjunction with the network of NEXRAD and spaceborne radars could provide valuable data for applications ranging from cumulus parameterization to 4D data assimilation and model initialization."
"57203053317;7005453346;6602410830;6602774744;7005828214;","Comparing different cloud schemes of a single column model by using mesoscale forcing and nudging technique",1999,"10.1175/1520-0442(1999)012<0438:CDCSOA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033079620&doi=10.1175%2f1520-0442%281999%29012%3c0438%3aCDCSOA%3e2.0.CO%3b2&partnerID=40&md5=d15176a150ab2dce6fcec48adb916532","Different cloud schemes are compared using the single column model (SCM) version of the general circulation model of the Canadian Centre for Climate Modelling and Analysis. Emphasis is placed on the differences between a statistical cloud scheme and an explicit one, two approaches commonly used in GCMs. The microphysical processes are identical in both schemes so that the differences can be attributed to cloud formation and dissipation only. Two case studies are chosen, one for a day during the European Cloud and Radiation Experiment (EUCREX) and one for a day during the North Atlantic Regional Experiment (NARE). During the EUCREX case study the SCM is forced by advection from the mesoscale model GESIMA (Geesthacht Simulation Model of the Atmosphere). The comparison of ice water content as a function of height shows that the SCM cannot reproduce the observed nearly linear decrease with height as well as GESIMA does above 8.5 km. If temperature, specific humidity, and cloud ice advection are used to force the SCM, the explicit scheme simulates a coherent thick cirrus cloud, which is in better agreement with observations than the separate cloud layers simulated with the statistical scheme. Sensitivity studies show that cloud ice advection is crucial for the formation of the cirrus deck in this case study, but omitting specific humidity advection improves the agreement with observations. During the NARE case study four sequential vertical profiles are available so that wind, temperature, and moisture of the SCM can be nudged toward their observed values. The observed lifting of the boundary layer cloud with time is captured best by the statistical scheme when adjusted toward observations with a relaxation timescale of one hour or less.Different cloud schemes are compared using the single column model (SCM) version of the general circulation model of the Canadian Centre for Climate Modelling and Analysis. Emphasis is placed on the differences between a statistical cloud scheme and an explicit one, two approaches commonly used in GCMs. The micro-physical processes are identical in both schemes so that the differences can be attributed to cloud formation and dissipation only. Two case studies are chosen, one for a day during the European Cloud and Radiation Experiment (EUCREX) and one for a day during the North Atlantic Regional Experiment (NARE). During the EUCREX case study the SCM is forced by advection from the mesoscale model GESIMA (Geesthacht Simulation Model of the Atmosphere). The comparison of ice water content as a function of height shows that the SCM cannot reproduce the observed nearly linear decrease with height as well as GESIMA does above 8.5 km. If temperature, specific humidity, and cloud ice advection are used to force the SCM, the explicit scheme simulates a coherent thick cirrus cloud, which is in better agreement with observations than the separate cloud layers simulated with the statistical scheme. Sensitivity studies show that cloud ice advection is crucial for the formation of the cirrus deck in this case study, but omitting specific humidity advection improves the agreement with observations. During the NARE case study four sequential vertical profiles are available so that wind, temperature, and moisture of the SCM can be nudged toward their observed values. The observed lifting of the boundary layer cloud with time is captured best by the statistical scheme when adjusted toward observations with a relaxation timescale of one hour or less."
"57199000416;7202208382;7202899330;","A simple radiative-convective model with a hydrological cycle and interactive clouds",1999,"10.1002/qj.49712555505","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032765966&doi=10.1002%2fqj.49712555505&partnerID=40&md5=d5d37eea5db64ce1bca4ac08e71baff0","We have developed a simple, analytically tractable radiative-convective model of the tropical climate system that includes an explicit moisture budget, a simple convection parametrization, a simple but physically based radiation parametrization, and interactive clouds. The underlying surface is assumed to be ocean. The model includes prognostic equations for the sea surface temperature and the vertically integrated water vapour content. A stratosphere in radiative equilibrium limits the depth of the convective layer. The lower-tropospheric lapse rate, surface evaporation rate, and clear-sky long-wave and short-wave radiative fluxes at the surface and the top of the atmosphere are determined as functions of the sea surface temperature and precipitable water only. The radiative-convective equilibria of the model atmosphere resemble the observed tropical climate, if realistic sea surface temperatures are prescribed. However, cloud-free radiative-convective equilibria of the tropical atmosphere-ocean system do not occur for realistic values of the surface albedo. When cloud radiative effects are included, the model produces radiative-convective equilibria that are unrealistically warm. With prescribed realistic lateral energy and moisture transports, however, the equilibria of the model are realistic."
"7402205043;56962915800;","The role of longwave radiation and boundary layer thermodynamics in forcing tropical surface winds",1999,"10.1175/1520-0442(1999)012<1049:TROLRA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033117280&doi=10.1175%2f1520-0442%281999%29012%3c1049%3aTROLRA%3e2.0.CO%3b2&partnerID=40&md5=878fd82c5b8b77ce323f7c113f1d5207","This paper reveals major deficiencies of the existing intermediate climate models for tropical surface winds and elaborates the important roles of cloud-longwave radiational forcing and boundary layer thermodynamics in driving the tropical surface winds. The heat sink associated with the cloud-longwave radiation is demonstrated as an important driving force for boreal summer northeast trades and Indian Ocean southwest monsoons. Over the western North Pacific and Atlantic Oceans, low cloudiness and high sea surface temperature enhance longwave radiation cooling, strengthening subtropical high and associated trades. On the other hand, in the regions of heavy rainfall over South Asia, reduced cloud-longwave radiation cooling enhances monsoon trough and associated southwest monsoons. The boundary layer thermodynamic processes, primarily both the surface heat fluxes and the vertical temperature advection, are shown to be critical for a realistic simulation of the intertropical convergence zone, the equatorial surface winds, and associated divergence field. To successfully simulate the tropical surface winds, it is essential for intermediate models to adequately describe the feedback of the boundary layer frictional convergence to convective heat source, cloud-longwave radiation forcing, boundary layer temperature gradient forcing, and their interactions. The capability and limitations of the intermediate tropical climate model in reproducing both climatology and interannual variations are discussed.This paper reveals major deficiencies of the existing intermediate climate models for tropical surface winds and elaborates the important roles of cloud-longwave radiational forcing and boundary layer thermodynamics in driving the tropical surface winds. The heat sink associated with the cloud-longwave radiation is demonstrated as an important driving force for boreal summer northeast trades and Indian Ocean southwest monsoons. Over the western North Pacific and Atlantic Oceans, low cloudiness and high sea surface temperature enhance longwave radiation cooling, strengthening subtropical high and associated trades. On the other hand, in the regions of heavy rainfall over South Asia, reduced cloud-longwave radiation cooling enhances monsoon trough and associated southwest monsoons. The boundary layer thermodynamic processes, primarily both the surface heat fluxes and the vertical temperature advection, are shown to be critical for a realistic simulation of the intertropical convergence zone, the equatorial surface winds, and associated divergence field. To successfully simulate the tropical surface winds, it is essential for intermediate models to adequately describe the feedback of the boundary layer frictional convergence to convective heat source, cloud-longwave radiation forcing, boundary layer temperature gradient forcing, and their interactions. The capability and limitations of the intermediate tropical climate model in reproducing both climatology and interannual variations are discussed."
"56251307100;6603577857;7003566416;","Method for studies of the interaction between atmospheric aerosol particles and cloud and fog droplets",1999,"10.1016/S0021-8502(99)80302-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033189784&doi=10.1016%2fS0021-8502%2899%2980302-4&partnerID=40&md5=1f2d802996fe393d921e1e6d6ff41ead","In this study, the unipolar charging unit was calibrated with respect to the number of charges and the charge distribution obtained as a function of droplet diameter. Monodisperse droplets were generated with a TSI Vibrating Orifice Aerosol Generator. The charge distribution was measured with a Differential Mobility Analyzer (DMA) designed for large droplets. The droplet size and concentration were measured with a TSI Aerodynamic Particle Sizer (APS)."
"7202269082;6701392598;","British Tornadoes and Waterspouts of the 1970's, Part 8: 1979",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033022259&partnerID=40&md5=d6e48db15c5cd2f6fddd148816bb752b","A total of 28 tornadoes were reported in Britain in 1979 (21 definite and seven probable) and there were ten waterspouts or groups of waterspouts and seven funnel clouds (excluding funnel clouds accompanied by a tornado). The most powerful tornadoes were near Ablington (Wiltshire) on 30 May and at Windsor (Berkshire) on 24 June, both of which were of force T4."
"6603940684;7003899619;7103314258;","Analysis of cloud-radiative forcing derived from the AVHRR Pathfinder atmosphere (PATMOS) 16-year data set",1999,"10.1016/S0273-1177(99)00360-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033387330&doi=10.1016%2fS0273-1177%2899%2900360-9&partnerID=40&md5=5b2d53bd029f8a399798b19c0dc016fc","The influence of clouds on the Earth's radiation budget is analyzed using the PATMOS data set, which spans the period from July 1981 to the present. This data set resulted from reprocessing the Advanced Very High Resolution Radiometer (AVHRR) on-board NOAA sunsynchronous polar-orbiting satellites beginning with NOAA-7. Only satellites having an afternoon equator-crossing time were utilized. The PATMOS dataset, produced as part of the NOAA/NASA Pathfinder Program, provides atmospheric products, which include top of the atmosphere broadband estimates of outgoing longwave and absorbed solar radiation (cloudy and clear-sky). Computation of the differences between the cloudy and clear-sky radiation components (cloud-radiative forcing) yield estimates of the effects of clouds on the radiation. Variations in the cloud-radiative forcing are examined to detect seasonal to interannual climate anomalies, such as caused by the recent El Nino."
"7003466102;","The influence of solar zenith angle and cloud type on cloud radiative forcing at the surface in the arctic",1999,"10.1175/1520-0442-12.1.147","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033053432&doi=10.1175%2f1520-0442-12.1.147&partnerID=40&md5=77c41838f664c4330c32663e96cbc339","Measurements of the long- and shortwave incident radiation taken from the USCGC Polar Sea during a research cruise to the Northeast Water Polynya during the summer of 1993 are analyzed together with observations of cloud type and amount to determine the effects of summertime Arctic clouds on the surface radiation budget. It is found that the solar zenith angle is critical in determining whether clouds heat or cool the surface. For large solar zenith angles (>to approximately 80°) the infrared heating effect of clouds is greater than the reduction in insolation caused by clouds, and the surface is heated by the presence of cloud. For smaller zenith angles, cloud cover cools the surface, and for intermediate zenith angles, the surface radiation budget is insensitive to the presence of, or changes in, cloud cover.Measurements of the long- and shortwave incident radiation taken from the USCGC Polar Sea during a research cruise to the Northeast Water Polynya during the summer of 1993 are analyzed together with observations of cloud type and amount to determine the effects of summertime Arctic clouds on the surface radiation budget. It is found that the solar zenith angle is critical in determining whether clouds heat or cool the surface. For large solar zenith angles (>~80°) the infrared heating effect of clouds is greater than the reduction in insolation caused by clouds, and the surface is heated by the presence of cloud. For smaller zenith angles, cloud cover cools the surface, and for intermediate zenith angles, the surface radiation budget is insensitive to the presence of, or changes in, cloud cover."
"56000281400;7007108728;","Scale effects on averaging of cloud droplet and aerosol number concentrations: Observations and models",1999,"10.1175/1520-0442(1999)012<1268:SEOAOC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032884825&doi=10.1175%2f1520-0442%281999%29012%3c1268%3aSEOAOC%3e2.0.CO%3b2&partnerID=40&md5=a976e115ed760de803fb4dbda13811c2","The purpose of this study, using in situ observations from five field projects, is to analyze cloud boundaries and averaging scales related to droplet number concentration (Nd) and total aerosol number concentration (Na), and to discuss parameterizations of these variables for use in numerical weather prediction and global climate models. Here Nd and Na for stratus and stratocumulus clouds are averaged over various lengths from 1 km up to 35 km. The relationships between these variables for 1-s and 200-s data are compared with current parameterizations. Comparisons between Nd and Na show that Na plays an important role for activating cloud droplets. The variability in Nd from 1-s data is estimated to have a standard deviation of about ± 150 cm-3. Median values of Nd representing scales from about 0.1 km up to approximately 35 km are found to be dependent on scale and the presence of clear patches in the clouds. The average values of Nd are also dependent on the lower concentration threshold used to define the cloud boundaries. It is concluded that scale effects, including clear air regions, should be considered when developing parameterization schemes used for modeling studies of cloud systems."
"36862677400;7202145115;7402064802;","The role of clouds, water vapor, circulation, and boundary layer structure in the sensitivity of the tropical climate",1999,"10.1175/1520-0442(1999)012<2359:trocwv>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033172679&doi=10.1175%2f1520-0442%281999%29012%3c2359%3atrocwv%3e2.0.co%3b2&partnerID=40&md5=610d77aae97bee07ed5a0d8670be08f9","The physical mechanisms that affect the tropical sea surface temperature (SST) are investigated using a two-box equilibrium model of the Tropics. One box represents the convecting, warm SST, high humidity region of the Tropics, and the other box represents the subsidence region with low humidity, boundary layer clouds, and cooler SST. The two regions communicate by energy and moisture fluxes that are proportional to the strength of the overturning circulation that couples the two regions. The boundary layer properties in the subsiding region are predicted with a mixing line model. Humidity above the inversion in the subsiding region is predicted from moisture conservation. The humidity above the inversion in the subsiding region increases rapidly with temperature, but this has less effect on the sensitivity than expected, because the inversion lowers as the humidity above the inversion is increased. Some of the increased greenhouse effect of the free troposphere can be offset by decreased greenhouse effect of the boundary layer. Increasing the area of the warm, convective region increases the SSTs, because of the greenhouse effect of the greater upper-tropospheric water vapor in the convective region. The circulation strength is constrained by radiative cooling in the cold pool. The strength of the circulation decreases with increasing convective area, because the increase in dry static stability overwhelms the increase in cooling rate. Although they have strong individual effects on longwave and shortwave radiation, high clouds in the convective region do not affect the tropical SSTs strongly, because their net radiative forcing at the top of the atmosphere is small. Low clouds in the subsidence region have a strong cooling affect on the tropical SST, because they strongly reduce net radiative heating at the top of the atmosphere. A negative feedback is produced if the low clouds are predicted from the observed relationship between stratus cloud amount and lower-tropospheric stability."
"7006082600;","Optical and geometrical properties of northern midlatitude cirrus clouds observed with a UV Raman Lidar",1999,"10.1016/S1464-1909(98)00047-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032869919&doi=10.1016%2fS1464-1909%2898%2900047-1&partnerID=40&md5=2a690c776d5786861e85c7cad54f26fd","Measurements of cirrus optical and geometrical properties of are presented. Data have been taken at Geesthacht (53.5 °N, 10.5 °E) in northern Germany between May 1994 and March 1996. The instrument used for this purpose is a two-laser UV Raman DIAL for simultaneous and independent measurements of ozone, water vapor and clouds. The combination of the Raman lidar technique and the polarization lidar technique yields the most complete set of cirrus cloud parameters measured remotely so far. A statistical analysis of cirrus midcloud height and temperature, top height and temperature, and of cirrus geometrical and optical depth is presented and discussed. The cloud mean extinction, geometrical and optical depths, lidar ratio and depolarization ratio are given as a function of midcloud temperature. For the first time the dependence of the lidar ratio upon the depolarization ratio is investigated. The material presented is considered as an important data basis for the modeling of the effects of cirrus clouds on climate."
"6602382901;7202233375;","Cloud transmission estimates of UV-B erythermal irradiance",1999,"10.1007/s007040050100","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032731864&doi=10.1007%2fs007040050100&partnerID=40&md5=f43af6cdd61d300b5934c4aa02fc14fa","Two UV-Biometer 501A instruments were used to estimate global erythemal irradiance at two locations in southwest Sweden; the Earth Sciences Centre, University of Goteborg (57.69°N; 11.92°E) and the island of Nordkoster, 200 km to the north (58.83°N; 10.72°E). A semi-empirical radiative transfer model was used to calculate the global erythemally effective irradiance under clear skies. A ratio of the hourly measured to clear-sky modelled irradiance was then derived for zenith angles 35-70°. Subsequent comparisons were then made with routine measurements of sunshine duration at Goteborg and sunshine duration, cloud cover, type and height at Nordkoster. Cloud transmission of UV-B irradiance decreases with increasing solar zenith angle, with cloud attenuation being 8% stronger at Nordkoster Island for zenith angles >60°. Transmission also decreases with increasing cloud cover such that overcast cloud conditions reduce transmissions by an average of 75%. In addition, cloud type affects the amount of ground incident irradiant flux. Fractus cloud afforded the least UV-B transmission (0.16), while cirrus filaments afforded the most (0.95). The spatial and temporal distribution of clouds appears to be non-random. Under conditions of 1 to 3 octas, sky cover, clouds appear to be concentrated in line with the sensor and Sun on more occasions than that expected given a random cloud distribution. The same cloud cover condition also resulted in many instances of ground incident irradiance above clear-sky values. The presence of cumuliform clouds appears to increase the likelihood of the latter phenomena."
"7801693068;7202208382;","Sensitivity of the simulated Asian summer monsoon to parameterized physical processes",1999,"10.1029/1999JD900168","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033609251&doi=10.1029%2f1999JD900168&partnerID=40&md5=6175b956fc6e33890a6a4d87f356e080","A study of the sensitivity of the simulated Asian summer monsoon to changes in general circulation model formulation is reported. The baseline version of the model fails to realistically simulate the precipitation, wind, and temperature fields. In one experiment the stratiform cloud parameterization was changed from a simple large-scale saturation scheme to a scheme that prognostically determines cloud water, cloud ice, and rain. In a second experiment a parameter that relates the cumulus mass flux to the cumulus kinetic energy was altered so as to increase the convective adjustment time. These changes in the stratiform and cumuliform cloud parameterizations significantly improve the simulations of the precipitation and upper level wind fields, respectively. Copyright 1999 by the American Geophysical Union."
"7006393267;7006738324;7202162685;7404416268;7005892627;","Review of Science issues, deployment strategy, and status for the ARM North Slope of Alaska-Adjacent Arctic Ocean climate research site",1999,"10.1175/1520-0442-12.1.46","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033011823&doi=10.1175%2f1520-0442-12.1.46&partnerID=40&md5=d3b32b79c3606d26512688f970d653e7","Recent climate modeling results point to the Arctic as a region that is particularly sensitive to global climate change. The Arctic warming predicted by the models to result from the expected doubling of atmospheric carbon dioxide is two to three times the predicted mean global warming, and considerably greater than the warming predicted for the Antarctic. The North Slope of Alaska-Adjacent Arctic Ocean (NSA-AAO) Cloud and Radiation Testbed (CART) site of the Atmospheric Radiation Measurement (ARM) Program is designed to collect data on temperature-ice-albedo and water vapor-cloud-radiation feedbacks, which are believed to be important to the predicted enhanced warming in the Arctic. The most important scientific issues of Arctic, as well as global, significance to be addressed at the NSA-AAO CART site are discussed, and a brief overview of the current approach toward, and status of, site development is provided. ARM radiometric and remote sensing instrumentation is already deployed and taking data in the perennial Arctic ice pack as part of the SHEBA (Surface Heat Budget of the Arctic Ocean) experiment. In parallel with ARM's participation in SHEBA, the NSA-AAO facility near Barrow was formally dedicated on 1 July 1997 and began routine data collection early in 1998. This SHEBA program (funded primarily by the National Science Foundation and the Office of Naval Research) to be mutually supportive. In addition, location of the NSA-AAO Barrow facility on National Oceanic and Atmospheric Administration land immediately adjacent to its Climate Monitoring and Diagnostic Laboratory Barrow Observatory includes NOAA in this major interagency Arctic collaboration.Recent climate modeling results point to the Arctic as a region that is particularly sensitive to global climate change. The Arctic warming predicted by the models to result from the expected doubling of atmospheric carbon dioxide is two to three times the predicted mean global warming, and considerably greater than the warming predicted for the Antarctic. The North Slope of Alaska-Adjacent Arctic Ocean (NSA-AAO) Cloud and Radiation Testbed (CART) site of the Atmospheric Radiation Measurement (ARM) Program is designed to collect data on temperature-ice-albedo and water vapor-cloud-radiation feedbacks, which are believed to be important to the predicted enhanced warming in the Arctic. The most important scientific issues of Arctic, as well as global, significance to be addressed at the NSA-AAO CART site are discussed, and a brief overview of the current approach toward, and status of, site development is provided. ARM radiometric and remote sensing instrumentation is already deployed and taking data in the perennial Arctic ice pack as part of the SHEBA (Surface Heat Budget of the Arctic Ocean) experiment. In parallel with ARM's participation in SHEBA, the NSA-AAO facility near Barrow was formally dedicated on 1 July 1997 and began routine data collection early in 1998. This schedule permits the U.S. Department of Energy's ARM Program, NASA's Arctic Cloud program, and the SHEBA program (funded primarily by the National Science Foundation and the Office of Naval Research) to be mutually supportive. In addition, location of the NSA-AAO Barrow facility on National Oceanic and Atmospheric Administration land immediately adjacent to its Climate Monitoring and Diagnostic Laboratory Barrow Observatory includes NOAA in this major interagency Arctic collaboration."
"7102739935;7005703578;55768583400;","Representing twentieth-century space-time climate variability. Part I: Development of a 1961-90 mean monthly terrestrial climatology",1999,"10.1175/1520-0442(1999)012<0829:rtcstc>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033102436&doi=10.1175%2f1520-0442%281999%29012%3c0829%3artcstc%3e2.0.co%3b2&partnerID=40&md5=7416ebef92b7f4d1231059befcca638c","The construction of a 0.5° lat × 0.5° long surface climatology of global land areas, excluding Antarctica, is described. The climatology represents the period 1961-90 and comprises a suite of nine variables: precipitation, wet-day frequency, mean temperature, diurnal temperature range, vapor pressure, sunshine, cloud cover, ground frost frequency, and wind speed. The climate surfaces have been constructed from a new dataset of station 1961-90 climatological normals, numbering between 19 800 (precipitation) and 3615 (wind speed). The station data were interpolated as a function of latitude, longitude, and elevation using thin-plate splines. The accuracy of the interpolations are assessed using cross validation and by comparison with other climatologies. This new climatology represents an advance over earlier published global terrestrial climatologies in that it is strictly constrained to the period 1961-90, describes an extended suite of surface climate variables, explicitly incorporates elevation as a predictor variable, and contains an evaluation of regional errors associated with this and other commonly used climatologies. The climatology is already being used by researchers in the areas of ecosystem modelling, climate model evaluation, and climate change impact assessment. The data are available from the Climatic Research Unit and images of all the monthly fields can be accessed via the World Wide Web."
"7005977685;6602390997;16227726200;","Seasonal and daily cycles of a pollen cloud on the south of Western Siberia",1999,"10.1016/S0021-8502(99)80377-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033189573&doi=10.1016%2fS0021-8502%2899%2980377-2&partnerID=40&md5=ec636aa8ed862aa6b3227f893123f884","Content of a pollen atmospheric aerosol component in the air has been studied in 1995-1998 during a vegetative period using the Institute's roof as observation site. The seasonal variations in the pollen content in the air were observed using horizontal sticky glasses exposed for 24 hrs. The data obtained show that the entire vegetative period in Novosibirsk can be conditionally divided into three stages: the blossoming of wooden plants - ingress of the main mass of pollen grains into the atmosphere: cereal blossoming; and grass blossoming."
"57209516655;7006393267;7006246996;","Remote sensing of surface and cloud properties in the Arctic from AVHRR measurements",1999,"10.1175/1520-0450(1999)038<0989:RSOSAC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032754461&doi=10.1175%2f1520-0450%281999%29038%3c0989%3aRSOSAC%3e2.0.CO%3b2&partnerID=40&md5=1d021ce185ae7946aa14a679b4d96000","Algorithms to retrieve cloud optical depth and effective radius in the Arctic using Advanced Very High Resolution Radiometer (AVHRR) data are developed, using a comprehensive radiative transfer model in which the atmosphere is coupled to the snowpack. For dark surfaces AVHRR channel 1 is used to derive visible cloud optical depth, while for bright surfaces AVHRR channel 2 is used. Independent inference of cloud effective radius from AVHRR channel 3 (3.75 μm) allows for derivation cloud liquid water path (proportional to the product of optical depth and effective radius), which is a fundamental parameter of the climate system. The algorithms are based on the recognition that the reflection function of clouds at a nonabsorbing wavelength (such as AVHRR channel 1) in the solar spectrum is primarily a function of cloud optical thickness, whereas the reflection function at a liquid water absorbing wavelength (such as AVHRR channel 3) is primarily a function of cloud particle size. For water clouds over highly reflecting surfaces (snow and ice), the reflectance in AVHRR channel 1 is insensitive to cloud optical depth due to the multiple reflections between cloud base and the underlying surface; channel 2 (0.85 μm) must be used instead for optical depth retrieval. Water clouds over tundra or ocean are more straightforward cases similar to those found at lower latitudes, and in these cases a comprehensive atmospheric radiative transfer model with a Lambertian surface under cloud is used. Thus, for water cloud over tundra and ocean, channel 1 is used for cloud optical depth retrieval. In all cases, channel 3 is used for independent retrieval of cloud droplet effective radius. The thermal component of channel 3 is estimated by making use of channel 4 (11 μm) and is subtracted from the total channel 3 radiance. Over clear-sky scenes, the bidirectional reflectance properties of snow are calculated directly by the coupled snowpack-atmosphere model. This results in greater overall accuracy in retrieved surface properties as compared with the simplified approach that uses a Lambertian approximation for the surface albedo. To test the physical soundness of the algorithms the authors have applied them to AVHRR data over Barrow, Alaska, from April to August 1992. Downwelling irradiances at the surface calculated using the retrieved cloud optical depth and effective radius are compared with field irradiance measurements, and encouraging agreement is found. The algorithms are also applied to three areas of about 100-km dimension around Barrow, each having a different underlying surface (ocean, tundra, snow).Algorithms to retrieve cloud optical depth and effective radius in the Arctic using Advanced Very High Resolution Radiometer (AVHRR) data are developed, using a comprehensive radiative transfer model in which the atmosphere is coupled to the snowpack. For dark surfaces AVHRR channel 1 is used to derive visible cloud optical depth, while for bright surfaces AVHRR channel 2 is used. Independent inference of cloud effective radius from AVHRR channel 3 (3.75 μm) allows for derivation cloud liquid water path (proportional to the product of optical depth and effective radius), which is a fundamental parameter of the climate system. The algorithms are based on the recognition that the reflection function of clouds at a nonabsorbing wavelength (such as AVHRR channel 1) in the solar spectrum is primarily a function of cloud optical thickness, whereas the reflection function at a liquid water absorbing wavelength (such as AVHRR channel 3) is primarily a function of cloud particle size. For water clouds over highly reflecting surfaces (snow and ice), the reflectance in AVHRR channel 1 is insensitive to cloud optical depth due to the multiple reflections between cloud base and the underlying surface; channel 2 (0.85 μm) must be used instead for optical depth retrieval. Water clouds over tundra or ocean are more straightforward cases similar to those found at lower latitudes, and in these cases a comprehensive atmospheric radiative transfer model with a Lambertian surface under cloud is used. Thus, for water cloud over tundra and ocean, channel 1 is used for cloud optical depth retrieval. In all cases, channel 3 is used for independent retrieval of cloud droplet effective radius. The thermal component of channel 3 is estimated by making use of channel 4 (11 μm) and is subtracted from the total channel 3 radiance. Over clear-sky scenes, the bidirectional reflectance properties of snow are calculated directly by the coupled snowpack-atmosphere model. This results in greater overall accuracy in retrieved surface properties as compared with the simplified approach that uses a Lambertian approximation for the surface albedo. To test the physical soundness of the algorithms the authors have applied them to AVHRR data over Barrow, Alaska, from April to August 1992. Downwelling irradiances at the surface calculated using the retrieved cloud optical depth and effective radius are compared with field irradiance measurements, and encouraging agreement is found. The algorithms are also applied to three areas of about 100-km dimension around Barrow, each having a different underlying surface (ocean, tundra, snow)."
"23082420800;7003531755;","Climate and the tropical oceans",1999,"10.1175/1520-0442(1999)012<3383:CATTO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033493974&doi=10.1175%2f1520-0442%281999%29012%3c3383%3aCATTO%3e2.0.CO%3b2&partnerID=40&md5=836925fc697a1c7b3cb1155e3046e516","An attempt is made to determine the role of the ocean in establishing the mean tropical climate and its sensitivity to radiative perturbations. A simple two-box energy balance model is developed that includes ocean heat transports as an interactive component of the tropical climate system. It is found that changes in the zonal mean ocean heat transport can have a considerable affect on the mean tropical sea surface temperature (SST) through their effect on the properties of subtropical marine stratus clouds or on the water vapor greenhouse effect of the tropical atmosphere. The way that the tropical climate adjusts to changes in the ocean heat transport is primarily through the atmospheric heat transport, without changing the net top of the atmosphere radiative balance. Thus, the total amount of low-latitude poleward heat transport is invariant with respect to changes in ocean circulation in this model. These results are compared with analogous experiments with general circulation models. Doubled CO2 experiments are performed with different values of ocean heat transport. It is found that the sensitivity of the mean tropical SST to doubled CO2 depends on the strength of the ocean heat transport due to feedbacks between the ocean and subtropical marine stratus clouds and the water vapor greenhouse effect. In this model, the results are the same whether the ocean heat transports are determined interactively or are fixed. Some recent studies have suggested that an increased meridional overturning in the ocean due to changes in the zonally asymmetric circulation can reduce the sensitivity of the tropical climate to increased CO2. It is found that, in equilibrium, this is not that case, but rather an increase in ocean heat transport, which involves increased equatorial upwelling, actually warms the tropical climate.An attempt is made to determine the role of the ocean in establishing the mean tropical climate and its sensitivity to radiative perturbations. A simple two-box energy balance model is developed that includes ocean heat transports as an interactive component of the tropical climate system. It is found that changes in the zonal mean ocean heat transport can have a considerable affect on the mean tropical sea surface temperature (SST) through their effect on the properties of subtropical marine stratus clouds or on the water vapor greenhouse effect of the tropical atmosphere. The way that the tropical climate adjusts to changes in the ocean heat transport is primarily through the atmospheric heat transport, without changing the net top of the atmosphere radiative balance. Thus, the total amount of low-latitude poleward heat transport is invariant with respect to changes in ocean circulation in this model. These results are compared with analogous experiments with general circulation models. Doubled CO2 experiments are performed with different values of ocean heat transport. It is found that the sensitivity of the mean tropical SST to doubled CO2 depends on the strength of the ocean heat transport due to feedbacks between the ocean and subtropical marine stratus clouds and the water vapor greenhouse effect. In this model, the results are the same whether the ocean heat transports are determined interactively or are fixed. Some recent studies have suggested that an increased meridional overturning in the ocean due to changes in the zonally asymmetric circulation can reduce the sensitivity of the tropical climate to increased CO2. It is found that, in equilibrium, this is not that case, but rather an increase in ocean heat transport, which involves increased equatorial upwelling, actually warms the tropical climate."
"7006698304;7402064802;","The role of vertically varying cloud fraction in the parametrization of microphysical processes in the ECMWF model",1999,"10.1256/smsqj.55509","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032766611&doi=10.1256%2fsmsqj.55509&partnerID=40&md5=14d1be53eeddb941acc86629c921ecc5","General-circulation models (GCMs) have generally treated solely the radiative impacts of vertically varying cloud fraction by using a cloud-overlap assumption. In this study, the microphysical impacts of vertically varying cloud fraction are addressed by developing a subgrid-scale precipitation model which resolves the vertical variation of cloud fraction. This subgrid model subdivides the grid boxes into homogeneous columns which are either clear or completely cloudy. By comparing the column-averaged microphysical quantities from the subgrid-scale precipitation model with the parametrization in the European Centre for Medium-Range Forecasts (ECMWF) model, the ability of the ECMWF model to account for the subgrid nature of cloud and precipitation microphysics is assessed. It is found that the ECMWF model overestimates the evaporation of precipitation in the tropical mid-troposphere. This results from (a) an incorrect parametrization of the area of the grid box covered by precipitation, and (b) the inadequacy of assuming a single value for the precipitation rate in the grid box. In addition to assessing the ability of the ECMWF model to parametrize the subgrid nature of cloud microphysics, the subgrid precipitation model is used to show that the cloud-overlap assumption has a large impact on the evaporation of precipitation. In light of the current trend towards more sophisticated cloud and precipitation parametrizations in GCMs, more attention should be paid to the impact of vertical cloud-fraction variations on the parametrized microphysics."
"7003679645;7006577693;57212781009;","A comparison of present and doubled CO2 climates and feedbacks simulated by three general circulation models",1999,"10.1029/1998JD200049","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608147&doi=10.1029%2f1998JD200049&partnerID=40&md5=6bbae084d3d39d07733695cb372f7ae7","The present and doubled CO2 equilibrium climates simulated by slab ocean versions of the atmospheric general circulation models from the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Mark 1 and Mark 2) and from the Bureau of Meteorology Research Centre (BMRC) are examined, with the aim of explaining the large variation in mean warming (4.8°C, 4.3°C, and 2.1°C). The present climates are compared firstly with observations. A graphical display of nondimensional measures of local and mean errors is used. For 15 quantities the models produce broadly similar skill, which indicates that such an evaluation is of limited use as a validation of these models for climate change prediction. Comparison of the two climates indicates that for temperature, snow/ice cover, and water column (but not necessarily other fields) the typical magnitudes of local changes are in rough proportion to the mean warming. For tropical precipitation, however, the BMRC model shows a similar sensitivity to CO2 doubling as do the CSIRO models. A standard diagnostic feedback analysis shows that the Mark 1 model has stronger albedo, water vapor, and cloud feedbacks than the BMRC model. A novel regional net feedback analysis is then applied to all three models. Feedbacks for the snow/ice region and clear-sky and cloud forcing components of the snow-free region indicate similar intermodel differences to those from the diagnostic approach. The feedbacks are examined in relation to the simulated climates and model parameterizations. As the application of the regional method requires only standard climatological fields, it is proposed as a convenient analysis tool in further model comparisons. Copyright 1999 by the American Geophysical Union."
"7404491637;7005540319;","Local climate influences on precipitation, cloud water, and dry deposition to an adirondack subalpine forest: Insights from observations 1986-1996",1999,"10.2134/jeq1999.00472425002800010033x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032939987&doi=10.2134%2fjeq1999.00472425002800010033x&partnerID=40&md5=2037c4315e9faea0edba841e6aff328b","Few studies of total atmospheric deposition (dry deposition, cloud droplet capture, rainfall, and snowfall) of major elements (S, N, Ca, Mg, and K) have been conducted in high-elevation forests. This paper presents the results of the first long-term observations (1986-1996) of total atmospheric deposition (wet + dry + cloud water) to a subalpine forest in the northeastern USA. Total atmospheric deposition of N to a forest at 1050 m elevation on Whiteface Mountain, NY, averaged 17.2 kg ha-1 yr-1, with 6.5 kg ha-1 yr-1 deposited as NH4 and 10.8 kg ha-1 yr-1 as NO3. Total S deposition averaged 18.3 kg ha-1 yr-1. Orographic effects both enhanced rainfall and increased interannual variance of ion concentrations and wet deposition compared to nearby low-elevation monitoring stations. Cloud droplet capture by the forest canopy varied substantially from year-to-year in response to changing meteorological conditions, contributing between 6 and 31% of total annual water inputs, which averaged 156.1 cm yr-1. Cloud water deposition was responsible for approximately 50%, and dry deposition approximately 10% of total annual N and S deposition. The signal from known decadal trends in atmospheric concentrations and fluxes of S in the northeastern USA was partially masked by high-frequency (intra- and inter- annual) variance associated with local climatic effects on precipitation and cloud water fluxes at this high-elevation site. These observations suggest that atmospheric deposition rates to high-elevation forests may be more responsive to climatic fluctuations and less responsive to recent and expected changes in atmospheric chemical burdens than in surrounding low- elevation ecosystems.Few studies of total atmospheric deposition (dry deposition, cloud droplet capture, rainfall, and snowfall) of major elements (S, N, Ca, Mg, and K) have been conducted in high-elevation forests. This paper presents the results of the first long-term observations (1986-1996) of total atmospheric deposition (wet+dry+cloud water) to a subalpine forest in the northeastern USA. Total atmospheric deposition of N to a forest at 1050 m elevation on Whiteface Mountain, NY, averaged 17.2 kg ha-1 yr-1, with 6.5 kg ha-1 yr-1 deposited as NH4 and 10.8 kg ha-1 yrMIN1 as NO3. Total S deposition averaged 18.3 kg ha-1 yr-1. Orographic effects both enhanced rainfall and increased interannual variance of ion concentrations and wet deposition compared to nearby low-elevation monitoring stations. Cloud droplet capture by the forest canopy varied substantially from year-to-year in response to changing meteorological conditions, contributing between 6 and 31% of total annual water inputs, which averaged 156.1 cm yr-1. Cloud water deposition was responsible for approximately 50%, and dry deposition approximately 10% of total annual N and S deposition. The signal from known decadal trends in atmospheric concentrations and fluxes of S in the northeastern USA was partially masked by high-frequency (intra- and inter-annual) variance associated with local climatic effects on precipitation and cloud water fluxes at this high-elevation site. These observations suggest that atmospheric deposition rates to high-elevation forests may be more responsive to climatic fluctuations and less responsive to recent and expected changes in atmospheric chemical burdens than in surrounding low-elevation ecosystems."
"55575353100;7102063963;7101890801;","Estimation of sea surface temperatures using GOES-8/9 radiance measurements",1999,"10.1175/1520-0477(1999)080<1127:EOSSTU>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000186834&doi=10.1175%2f1520-0477%281999%29080%3c1127%3aEOSSTU%3e2.0.CO%3b2&partnerID=40&md5=eb1838ee4d6c30426ac3b31854e70258","Sea surface temperatures (SSTs) are derived using measurements from the new generation of imaging instruments on the Geostationary Operational Environmental Satellites (GOES). The National Environmental Satellite, Data and Information Service has been producing hourly GOES SST estimates since December 1998. This paper presents the algorithm for cloud detection and atmospheric moisture correction and shows some initial results. Several advantages of GOES SST are evident in comparison with SST from polar orbiting satellites. Frequent sampling by GOES imagers results in a more complete map of SST as clouds move away. Changes in scene temperature over a short period of time help to detect the presence of clouds. The abundance of GOES observations enables stringent screening for cloud-free observations while maintaining good spatial coverage of clear-sky inferences of SST. Diurnal variations of SST over large areas are observed for the first time and their implications for numerical weather prediction and climate monitoring are discussed."
"7201742234;","Climate modelling: Achievements and prospects",1999,"10.1256/smsqj.55301","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032957913&doi=10.1256%2fsmsqj.55301&partnerID=40&md5=05b055db8cf5d08fbc304e4840d1efa4","The significant progress made with coupled (atmosphere-ocean) general-circulation models (CGCMs) over the past decade or so is discussed in the context of the reports of the Intergovernmental Panel on Climate Change (IPCC). In their first report in 1990, most climate-change GCMs were atmospheric GCMs coupled to 'slab' ocean models and being used only to determine the 'equilibrium' climate response to specified increases in carbon dioxide. The wide range of estimates of their 'climate sensitivity' is discussed, especially in the context of the uncertainty introduced by model sensitivity to representations of cloud. The modelling focus then moved to transient-response, climate-change experiments. These and the related modelling problems are noted; as are the simultaneous growing awareness and improved quantification of a range of natural and human-induced radiative forcings. The consequent inclusion of this information in CGCMs to study the detection and attribution of climate change, leading to the IPCC statement in their 1995 report that 'the balance of evidence suggests that there is a discernible human influence on global climate', is also discussed. A significant modelling breakthrough since the 1995 report is the capability of a few CGCMs to produce stable and realistic climate (control) simulations without using artificial 'flux adjustments'. This is illustrated with results from such a model, the Hadley Centre HadCM3. In conclusion, a brief perspective is given of high-priority modelling developments and applications to be addressed over the next decade."
"7102953444;57202413846;","The role of clouds and the cloud-free atmosphere in the problem of underestimated absorption of solar radiation in GCM atmospheres",1999,"10.1016/S1464-1909(98)00048-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032833510&doi=10.1016%2fS1464-1909%2898%2900048-3&partnerID=40&md5=9efbd3167ad9f4aee426fcbfd3fc125f","Large uncertainties exist to date in the distribution of solar radiation in the global climate system and its representation in General Circulation Models (GCMs). Based on a comprehensive dataset of collocated surface and satellite observations at more than 700 sites, it is shown that GCM atmospheres typically absorb too little solar radiation, in the range of 10-20 Wm-2. While several studies have pointed to a possible underestimation of solar absorption in clouds which may explain this bias, the present study shows evidence that the absorption in the cloud-free atmosphere is too small. These findings are based on a direct comparison of the GCM fluxes with observed clear-sky climatologies at surface radiation sites, and on off-line validations of the GCM radiation schemes for clear-sky conditions. Quantitatively, the absorption in the cloud-free GCM atmospheres is estimated to be too small on the order of 10 Wm-2, and even more in GCMs which neglect aerosol. Possible causes are an underestimation of solar absorption by water vapour and the neglect of aerosol effects. With respect to clouds, our observational data cannot exclude a possible lack of cloud absorption in GCMs at low latitudes, which is, however, unlikely to be as large as recently proposed. At higher latitudes, on the other hand, no evidence for a lack of cloud absorption in the GCMs is found when compared to the observational dataset. Overall, this study points out that in current GCMs not only the clouds, but also the cloud-free atmosphere can be responsible for the discrepancies between observational and simulated estimates of shortwave atmospheric absorption."
"7007088807;","Correlations to estimate monthly mean daily solar global irradiation: Application to Romania",1999,"10.1016/S0360-5442(99)00027-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033406438&doi=10.1016%2fS0360-5442%2899%2900027-4&partnerID=40&md5=dd355dd70f965920d78ede1a4de6c3b5","Seven existing relationships between monthly mean clearness index and the number of bright sunshine hours are tested under the climate and latitude of Romania. New (best-fit) correlations are derived. They use bright sunshine hour number or fractional total cloud amount as input. The dependence of the new sunshine-based regressions on month is stronger than their dependence on latitude. They generally underestimate the clearness index in the first half-year and overestimate it in the rest of the year. The accuracy of the new regression seems not to depend significantly on the year.Seven existing relationships between monthly mean clearness index and the number of bright sunshine hours are tested under the climate and latitude of Romania. New (best-fit) correlations are derived. They use bright sunshine hour number or fractional total cloud amount as input. The dependence of the new sunshine-based regressions on month is stronger than their dependence on latitude. They generally underestimate the clearness index in the first half-year and overestimate it in the rest of the year. The accuracy of the new regression seems not to depend significantly on the year."
"7003406400;7101867299;","Sensitivity of tropical convection to sea surface temperature in the absence of large-scale flow",1999,"10.1175/1520-0442(1999)012<0462:SOTCTS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033080089&doi=10.1175%2f1520-0442%281999%29012%3c0462%3aSOTCTS%3e2.0.CO%3b2&partnerID=40&md5=143927d62fdb4629672545071bd5cdee","The response of convection to changing sea surface temperature (SST) in the absence of large-scale flow is examined, using a three-dimensional cloud resolving model. The model includes a five-category bulk microphysical scheme representing snow, ice, graupel, rain, and cloud amounts in addition to an interactive radiation scheme for the shortwave and infrared. Long integrations are made to achieve a radiative-convective equilibrium state for SSTs of 298, 300, and 302 K, for which cloud and convection statistics are analyzed. The main conclusion of the paper is that, despite significant temperature sensitivities in many of the conversion terms between bulk water categories, convection is very insensitive to changing SST in the absence of large-scale flow. This is a result of the moist adiabatic temperature profile that the tropical atmosphere is constrained to take. A parcel of air rising through a deep convective cloud experiences approximately the same range of temperatures but at higher altitudes as SST increases. Thus the vertical profiles of cloud fraction and other cloud-related related statistics are simply shifted in height, but not changed in overall magnitude. The small changes in cloud properties that do occur lead to a small reduction in cloud fraction as SST increases. This appears to be due to an increase in graupel amounts with respect to snow, giving smaller cloud fractions since graupel has a higher fall velocity. The radiative effects of the changes in atmospheric properties are examined and it is found that the model atmosphere exhibits no supergreenhouse effect since atmospheric relative humidity is not altered significantly by the SST changes. The water vapor feedback effect is largely canceled by the change in temperature. Clouds have a negligibly small, but highly nonlinear, feedback in the model climate, in the absence of large-scale flow.The response of convection to changing sea surface temperature (SST) in the absence of large-scale flow is examined, using a three-dimensional cloud resolving model. The model includes a five-category bulk micro-physical scheme representing snow, ice, graupel, rain, and cloud amounts in addition to an interactive radiation scheme for the shortwave and infrared. Long integrations are made to achieve a radiative-convective equilibrium state for SSTs of 298, 300, and 302 K, for which cloud and convection statistics are analyzed. The main conclusion of the paper is that, despite significant temperature sensitivities in many of the conversion terms between bulk water categories, convection is very insensitive to changing SST in the absence of large-scale flow. This is a result of the moist adiabatic temperature profile that the tropical atmosphere is constrained to take. A parcel of air rising through a deep convective cloud experiences approximately the same range of temperatures but at higher altitudes as SST increases. Thus the vertical profiles of cloud fraction and other cloud-related statistics are simply shifted in height, but not changed in overall magnitude. The small changes in cloud properties that do occur lead to a small reduction in cloud fraction as SST increases. This appears to be due to an increase in graupel amounts with respect to snow, giving smaller cloud fractions since graupel has a higher fall velocity. The radiative effects of the changes in atmospheric properties are examined and it is found that the model atmosphere exhibits no supergreenhouse effect since atmospheric relative humidity is not altered significantly by the SST changes. The water vapor feedback effect is largely canceled by the change in temperature. Clouds have a negligibly small, but highly nonlinear, feedback in the model climate, in the absence of large-scale flow."
"6701773543;6507703419;55959710400;7004607037;","Volcanic aerosol effects on radiometric series registered at Spain",1999,"10.1016/S0021-8502(99)80456-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033189810&doi=10.1016%2fS0021-8502%2899%2980456-X&partnerID=40&md5=9f1a5fa142765373d7d4a08da32283f3","A study was conducted to follow the temporal evolution of the volcanic effects of El Chichon by means of broadband radiative fluxes measured at Madrid. The volcanic effects associated to Mt. Pinatubo as detected in Madrid data series were compared with those previously encountered in Almeria. Different components of broadband solar irradiance were measured. Aerosol effect was determined using cloud observations registered at Madrid and Almeria."
"7004540083;55275769500;","Advances in Understanding Clouds from ISCCP",1999,"10.1175/1520-0477(1999)080<2261:AIUCFI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042323504&doi=10.1175%2f1520-0477%281999%29080%3c2261%3aAIUCFI%3e2.0.CO%3b2&partnerID=40&md5=3fa5a0d021a9322dcb83942da617cf9d","This progress report on the International Satellite Cloud Climatology Project (ISCCP) describes changes made to produce new cloud data products (D data), examines the evidence that these changes are improvements over the previous version (C data), summarizes some results, and discusses plans for the ISCCP through 2005. By late 1999 all datasets will be available for the period from July 1983 through December 1997. The most significant changes in the new D-series cloud datasets are 1) revised radiance calibrations to remove spurious changes in the long-term record, 2) increased cirrus detection sensitivity over land, 3) increased low-level cloud detection sensitivity in polar regions, 4) reduced biases in cirrus cloud properties using an ice crystal microphysics model in place of a liquid droplet microphysics model, and 5) increased detail about the variations of cloud properties. The ISCCP calibrations are now the most complete and self-consistent set of calibrations available for all the weather satellite imaging radiometers: total relative uncertainties in the radiance calibrations are estimated to be ≲ 5% for visible and ≲ 2% for infrared; absolute uncertainties are < 10% and < 3%, respectively. Biases in (detectable) cloud amounts have been reduced to ≲ 0.05, except in the summertime polar regions where the bias may still be ∼ 0.10. Biases in cloud-top temperatures have been reduced to ≲ 2 K for lower-level clouds and ≲ 4 K for optically thin, upper-level clouds, except when they occur over lower-level clouds. Using liquid and ice microphysics models reduces the biases in cloud optical thicknesses to ≲ 10%, except in cases of mistaken phase identification; most of the remaining bias is caused by differences between actual and assumed cloud particle sizes and the small effects of cloud variations at scales < 5 km. Global mean cloud properties averaged over the period July 1983-June 1994 are the following: cloud amount = 0.675 ± 0.012; cloud-top temperature = 261.5 ± 2.8 K; and cloud optical thickness = 3.7 ± 0.3, where the plus-minus values are the rms deviations of global monthly mean values from their long-term average. Long-term, seasonal, synoptic, and diurnal cloud variations are illustrated. The ISCCP dataset quantifies the variations of cloud properties at mesoscale resolution (3 h, 30 km) covering the whole globe for more than a decade, making it possible to study cloud system evolution over whole life cycles, watching interactions with the atmospheric general circulation. Plans for the next decade of the World Climate Research Programme require continuing global observations of clouds and the most practical way to fulfill this requirement is to continue ISCCP until it can be replaced by a more capable system with similar time resolutions and global coverage."
"6701338417;7003961021;7006784145;55879643500;7005160468;7201898106;6603327182;7003877353;6603031910;7004639658;6602184993;7006212327;6603468918;6506182860;7004249622;57204302411;7005433221;7004085492;7403565272;7004005128;6603937716;6603604042;","Trajectory studies of polar stratospheric cloud lidar observations at Sodankyla (Finland) during SESAME: Comparison with box model results of particle evolution",1999,"10.1023/A:1006120226379","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032992514&doi=10.1023%2fA%3a1006120226379&partnerID=40&md5=3ad399d36a47b14048a79907597ddcf3","Polar stratospheric clouds (PSC) were observed with the multi-wavelength lidar of the MOANA project (Modelling and Observations of Aerosols in the Northern Atmosphere) during SESAME (Second European Stratospheric Arctic and Mid-latitude Experiment). The physical state, liquid or solid, of the cloud particles can be inferred from the lidar data. Using isentropic back-trajectories to obtain the thermal history of the sampled air masses, it is possible to reconcile most of the observations with current ideas on PSC formation and evolution. When the cloud particles were identified as liquid, changes in the size distribution of the droplets along the trajectory were calculated using a micro-physical box model. Backscatter ratios calculated from the size distributions are in broad agreement with the lidar data, giving confidence in current understanding of the evolution of ternary solution (H2SO4, HNO3 and H2O) droplets. Results from two soundings are shown which bear on the problem of the formation of solid particles. In the first, solid particles were detected. The air mass had cooled to the frost point 12 hours earlier. In the second no solid particles were detected although the air temperature was below the nitric acid trihydrate existence point, and had decreased by 12 K in the previous 14 hours."
"7003931528;57203053317;","Can a relaxation technique be used to validate clouds and sulphur species in a GCM?",1999,"10.1002/qj.1999.49712555609","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032774568&doi=10.1002%2fqj.1999.49712555609&partnerID=40&md5=420386cf27f58cf31d09bf33abce6833","The Hamburg version of the European Centre for Medium-Range Weather Forecasting (ECMWF) general circulation model, ECHAM4, developed for climate studies, is used to study the hydrological cycle and the atmospheric sulphur cycle. A technique, the Newtonian relaxation, is introduced to compare results from the model with measurements of cloud parameters and sulphur species concentrations. The model is forced by ECMWF analyses to simulate September 1993, and results are compared to observations on different spatial and temporal scales: monthly mean horizontal satellite data, daily mean averages at European and Canadian stations and aircraft soundings over the north Atlantic off the Canadian coast. The model is able to reproduce monthly mean horizontal distributions of liquid water path and precipitation. Daily mean precipitation fluxes and the temporal evolution of gaseous and particulate sulphur also agree quite well with observations. Based on this comparison with observations the performance of two different cloud physics parametrizations is discussed. These experiments indicate that variables like relative humidity, cloud cover and precipitation are controlled by the large-scale dynamics, whereas the cloud water content depends on the parametrization of the cloud microphysics. Coupling of the model-calculated sulphate mixing ratios to the cloud microphysics improves the model's sulphate distribution but slightly worsens the agreement between calculated and observed precipitation."
"7007114588;7102063963;","Eight years of high cloud statistics using HIRS",1999,"10.1175/1520-0442-12.1.170","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033011825&doi=10.1175%2f1520-0442-12.1.170&partnerID=40&md5=4114ab005a72566c68461a17116ca967","Over the last 8 yr frequency and location of cloud observations have been compiled using multispectral High Resolution Infrared Radiation Sounder (HIRS) data from the National Oceanic and Atmospheric Administration polar-orbiting satellites; this work is an extension of the 4-yr dataset reported by D. Wylie et al. The CO2 slicing algorithm applied to the HIRS data exhibits a higher sensitivity to semitransparent cirrus clouds than the cloud algorithm used by the International Satellite Cloud Climatology Project; the threshold for cloud detection appears to require visible optical depths (τ(vis)) greater than 0.1. The geographical distributions of clouds in the 8-yr dataset are nearly the same as those reported from 4 yr of data. The detection of upper-tropospheric clouds occurs most often in the intertropical convergence zone and midlatitude storm belts with lower concentrations in subtropical deserts and subtropical highs. The areas of concentrated cloud cover exhibit latitudinal movement with the seasons as in other cloud datasets. HIRS finds clear sky in 25%, opaque cloud in 32%, and semitransparent cloud in 43% of all its observations. The effective emissivity of the all semitransparent clouds (τ(vis) &lt; 6) ranges from 0.2 to 0.6 with an average value of about 0.5. Time trends are reexamined in detail. A possible cirrus increase in 1991 reported by Wylie and coauthors in 1994 is found to be diminished upon reinspection. The revised 8-yr record has indications of an increase in high clouds in the northern midlatitudes (0.5% yr-1) but little change elsewhere. The seasonal cycle of cloud cover in the Southern Hemisphere becomes very noticeable in 1993.Over the last 8 yr frequency and location of cloud observations have been compiled using multispectral High Resolution Infrared Radiation Sounder (HIRS) data from the National Oceanic and Atmospheric Administration polar-orbiting satellites; this work is an extension of the 4-yr dataset reported by D. Wylie et al. The CO2 slicing algorithm applied to the HIRS data exhibits a higher sensitivity to semitransparent cirrus clouds than the cloud algorithm used by the International Satellite Cloud Climatology Project; the threshold for cloud detection appears to require visible optical depths (τvis) greater than 0.1. The geographical distributions of clouds in the 8-yr dataset are nearly the same as those reported from 4 yr of data. The detection of upper-tropospheric clouds occurs most often in the intertropical convergence zone and midlatitude storm belts with lower concentrations in subtropical deserts and oceanic subtropical highs. The areas of concentrated cloud cover exhibit latitudinal movement with the seasons as in other cloud datasets. HIRS finds clear sky in 25%, opaque cloud in 32%, and semitransparent cloud in 43% of all its observations. The effective emissivity of the all semitransparent clouds (τvis&lt;6) ranges from 0.2 to 0.6 with an average value of about 0.5. Time trends are reexamined in detail. A possible cirrus increase in 1991 reported by Wylie and coauthors in 1994 is found to be diminished upon reinspection. The revised 8-yr record has indications of an increase in high clouds in the northern midlatitudes (0.5% yr-1) but little change elsewhere. The seasonal cycle of cloud cover in the Southern Hemisphere becomes very noticeable in 1993."
"55957189000;35592560600;7003931528;","Simulation of Mt. Pinatubo volcanic aerosol with the Hamburg climate model ECHAM4",1999,"10.1007/s007040050076","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032856912&doi=10.1007%2fs007040050076&partnerID=40&md5=8a524013fbb2c611664f261ae1093d8e","We study the three-dimensional transport of Mt. Pinatubo volcanic cloud with the climate model ECHAM4. In order to obtain model results comparable with observations a Newtonian relaxation technique was applied, which forces prognostic model variables towards the observations. A comparison of the simulated aerosol distribution with satellite data reveals good agreement for the first months after the eruption. The model, however, is unable to simulate the tropical aerosol maximum in 1992 and also overestimates the vertical downward and northward transport of aerosols. Substantial improvement was achieved with the introduction of reduced advective vertical transport through the 380 K isentropic layer. Heating rates and top of the atmosphere fluxes, which were calculated online for the first half year after the eruption, are in the observed range. A comparison of Pinatubo simulations between three different vertical ECHAM4 versions (ECHAM4 L19, ECHAM4 L39, MA/ECHAM4) indicates that a vertical resolution of ~700 m in the tropopause region is sufficient to realistically reduce the vertical transport through the tropopause. Consideration of the upper branch of the Brewer Dobson circulation in the MA/ECHAM4 model improves the geographical distribution of the volcanic cloud. The application of a relaxation technique can further reduce major shortcomings of stratospheric simulations with the standard climate model. There remain, however some critical points in the global transport characteristics in all three models which are not fully understood."
"7005942405;7004405044;7402612084;7501627905;7402170368;57198698671;8779962400;57206416522;8779962600;7004628271;7003810277;6603810350;8779963000;55742296300;","Integrated global system model for climate policy assessment: Feedbacks and sensitivity studies",1999,"10.1023/a:1005326126726","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033060835&doi=10.1023%2fa%3a1005326126726&partnerID=40&md5=9f7425d08c98c5e22c32e3d81633a168","Alternative policies to address global climate change are being debated in many nations and within the United Nations Framework Convention on Climate Change. To help provide objective and comprehensive analyses in support of this process, we have developed a model of the global climate system consisting of coupled sub-models of economic growth and associated emissions, natural fluxes, atmospheric chemistry, climate, and natural terrestrial ecosystems. The framework of this Integrated Global System Model is described and the results of sample runs and a sensitivity analysis are presented. This multi-component model addresses most of the major anthropogenic and natural processes involved in climate change and also is computationally efficient. As such, it can be used effectively to study parametric and structural uncertainty and to analyze the costs and impacts of many policy alternatives. Initial runs of the model have helped to define and quantify a number of feedbacks among the sub-models, and to elucidate the geographical variations in several variables that are relevant to climate science and policy. The effect of changes in climate and atmospheric carbon dioxide levels on the uptake of carbon and emissions of methane and nitrous oxide by land ecosystems is one potentially important feedback which has been identified. The sensitivity analysis has enabled preliminary assessment of the effects of uncertainty in the economic, atmospheric chemistry, and climate sub-models as they influence critical model results such as predictions of temperature, sea level, rainfall, and ecosystem productivity. We conclude that uncertainty regarding economic growth, technological change, deep oceanic circulation, aerosol radiative forcing, and cloud processes are important influences on these outputs."
"6701324864;7202162685;","A simple analytical model of aerosol properties with account for hygroscopic growth 1. Equilibrium size spectra and cloud condensation nuclei activity spectra",1999,"10.1029/98JD02673","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608142&doi=10.1029%2f98JD02673&partnerID=40&md5=7d509042b678116b2ab1784af45c6592","A microphysical model of aerosol size spectra that includes hygroscopic growth is presented. In the presence of atmospheric humidity, an aerosol size spectrum of Junge [1952] type transforms into a superposition of two equilibrium power law spectra, with indices determined by the original Junge index and the fraction of soluble material contained in the aerosol. The aerosol size distributions are presented as explicit functions of relative humidity H for three different humidity regimes: (1) moderate humidity, (2) high humidity but subsaturation, and (3) interstitial cloud aerosol. On the basis of this model of aerosol hygroscopic growth, the Twomey [1959] cloud condensation nuclei (CCN) power law is then derived so that its coefficients are related to the aerosol microstructure and humidity dependence under subsaturation. This simple aerosol model can be used in cloud and climate models that do not treat explicitly CCN activation and for evaluation of aerosol optical properties. An application for aerosol optical properties is considered by Khvorostyanov and Curry [this issue]. Copyright 1999 by the American Geophysical Union."
"56962915800;7601492669;","Dynamics of the ITCZ-equatorial cold tongue complex and causes of the latitudinal climate asymmetry",1999,"10.1175/1520-0442(1999)012<1830:DOTIEC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032695717&doi=10.1175%2f1520-0442%281999%29012%3c1830%3aDOTIEC%3e2.0.CO%3b2&partnerID=40&md5=99cd99ae6de063c350edb8d8d6ac91c9","The modification of a coupled atmosphere-ocean-coastline model driven by solar radiation is attempted. Using the extended model, the essential physics determining the annual cycle of the intertropical convergence zone (ITCZ)-equatorial cold tongue (ECT) complex and associated latitudinal climate asymmetry are highlighted.A coupled atmosphere-ocean-coastline model driven by solar radiation is advanced to understand the essential physics determining the annual cycle of the intertropical convergence zone (ITCZ)-equatorial cold tongue (ECT) complex and associated latitudinal climate asymmetry. With a thermocline depth similar to that of the western Pacific, the aquaplanet climate is latitudinal symmetric and stable. The presence of an oceanic eastern boundary supports an east-west asymmetric climate and an ECT due to unstable air-sea interaction and counter stabilization provided by zonal differential surface buoyancy flux. Formation of latitudinal climate asymmetry requires the presence of the ECT. The antisymmetric solar forcing due to annual variation of the solar declination angle can convert a stable latitudinal symmetric climate into a bistable-state latitudinal asymmetric climate by changing trade winds, which in turn control annual variations of the ECT. The ECT then interacts with ITCZ, providing a self-maintenance mechanism for ITCZ to linger in one hemisphere, either the northern or southern, depending on initial conditions. The establishment of the bistable-state asymmetry requires a delicate balance between counter effects of the antisymmetric solar forcing and self-maintenance. Two factors are critical for the latter: (i) The annual variation of ECT follows the SST of the ITCZ-free hemisphere and the meridional SST gradients between the ECT and ITCZ sustain moisture convergence, which prolongs residence of the ITCZ in summer hemisphere. (ii) The latent heat released in the ITCZ produces remarkable asymmetry in Hadley circulation and trades between the two hemispheres, and the stronger evaporation cooling in the ITCZ-free hemisphere delays and weakens the warming and convection development in that hemisphere. The annual cycle of insolation due to the earth-sun distance variation may convert the bistable-state asymmetry into a preferred latitudinal asymmetric climate. The earth's present orbit (with a minimum distance in December solstices) favors ITCZ staying north of the equator by compelling the ECT into a delayed in-phase variation with the Southern Hemisphere SST. With annual-mean solar forcing a tilted eastern boundary can support a weak preferred latitudinal asymmetry. Inclusion of the annual variation of insolation can dramatically amplify the asymmetry in the mean climate through the self-maintenance mechanism."
"26643250500;","Aviation-produced aerosols and contrails",1999,"10.1023/A:1006600107117","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033390519&doi=10.1023%2fA%3a1006600107117&partnerID=40&md5=d4fa75212dad31576ec668570ed9a102","Liquid and solid particles in the plumes of jet aircraft cruising in the upper troposphere and lower stratosphere lead to the formation of ice clouds (contrails), modify the microphysical properties of existing cirrus clouds, and provide sites for heterogeneous chemical reactions. Characterization of aviation-produced particles in terms of physico-chemical properties is an important step in assessing the global impact of aircraft emissions upon atmospheric chemistry and climate parameters. Chemistry and microphysics of the gas-aerosol system in aircraft plumes and its evolution in the atmosphere is a field of intense research. This paper reviews the current knowledge (mid-1998) and outlines possible atmospheric implications."
"7005955015;57193920163;23065650200;","A new parameterization scheme for the optical properties of ice crystals for use in general circulation models of the atmosphere",1999,"10.1016/S1464-1909(98)00043-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032852174&doi=10.1016%2fS1464-1909%2898%2900043-4&partnerID=40&md5=ad2a4877a352b6357417321ac239e59e","We present a new parameterization scheme for the optical properties of ice crystals, for use in general circulation models of the atmosphere (GCMs). The scheme consists of separate parameterizations for five different ice crystal shapes: hexagonal columns, hexagonal plates, bullet rosettes, spheres and planar polycrystals. The optical properties are specified as functions of the mean maximum dimension of the ice crystal size distribution using polynomial fits to a more elaborate scheme developed by the last author. The present scheme, based on 10th order fits, gives excellent accuracy and is efficient enough for use in GCMs. First, the scheme is tested on 1-dimensional models, showing a large sensitivity of albedo and emissivity to both ice crystal sizes and shapes. Also, long- and short-wave cloud radiative forcings at the top of the atmosphere are quite sensitive to those two parameters, in such a manner that the two effects do not cancel. It is shown that this may have a significant impact on climate sensitivity, through variations in net cloud forcing."
"7003613864;7402839597;9278228200;7102578937;7403221533;24281186100;","Closures between ground-based and spaceborn data for the development of retrieval procedures for aerosol properties",1999,"10.1016/S0021-8502(99)80227-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033189245&doi=10.1016%2fS0021-8502%2899%2980227-4&partnerID=40&md5=bac7a5e51d862c99649ec9096800125c","The determination of the aerosol type from the spectral optical thickness is one major task for an aerosol retrieval from space for the climate purpose. This requires the retrieval of the magnitude and the spectral slope of the optical thickness from top of atmosphere (TOA) radiances from spaceborne platforms and only can be made by a multiwavelength approach for homogeneous, cloud free pixel data. The main unknown aerosol property for an aerosol retrieval from spaceborne radiometers is the aerosol phase function. Several of the approaches for determining this unknown property are presented."
"6603081424;25941200000;","Accounting for subgrid-scale cloud variability in a multi-layer 1D solar radiative transfer algorithm",1999,"10.1002/qj.49712555316","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032913971&doi=10.1002%2fqj.49712555316&partnerID=40&md5=ecde228c98b80f08a7bd79ea42a4d1aa","A multi-layer, 1D solar radiative transfer algorithm that accounts for subgrid-scale cloud variability is presented. This algorithm is efficient and suitable for use in large-scale models such as global climate and weather prediction models. While it is built on the same principles as standard multi-layer 1D codes, there are two major differences. First, it is assumed that for all cloudy layers all the time, frequency distributions of optical depth τ are described by gamma probability density functions pΓ(τ) and characterized by mean optical depth τ and a variance-related parameter v. Albedos and transmittances for individual layers are estimated by integrals over all τ of the plane-parallel, homogeneous two-stream approximation equations weighted by pΓ(τ). Thus, the model is referred to as the gamma-weighted two-stream approximation. Second, in an attempt to counteract the use of horizontally homogeneous fluxes, a method was devised that often reduces layer values of τ. The gamma-weighted two-stream approximation was implemented in a well known broadband column model and the parametrizations upon which it is built were tested using 2D and 3D inhomogeneous cloud fields generated by a bounded cascade model and cloud-resolving models. All fields resolved the lowest 20 km of the atmosphere into at least 30 layers. Reference calculations were obtained by: (i) applying the 1D-plane-parallel, homogeneous model to each column and averaging (the independent column approximation); and (ii) a 3D Monte Carlo algorithm. The gamma-weighted two-stream approximation, the regular plane-parallel, homogeneous, and two other 1D models operated on horizontally-averaged versions of the fields (i.e. 1D vectors of cloud fraction, τ, and v). For several demanding cases, the gamma-weighted two-stream approximation reduced plane-parallel, homogeneous-biases for TOA albedo and surface irradiance by typically more than 85%. Moreover, it estimates of atmospheric heating rates usually differed from the independent column approximation and Monte Carlo values by less than 10%. This translates into heating rate errors that are four to eight times smaller than those associated with conventional 1D plane-parallel, homogeneous algorithms. In a large-scale model, a multi-layer solar code with the gamma-weighted two-stream approximation should require about twice as much CPU time as its plane-parallel, homogeneous counterpart."
"7003748648;6701847229;6603096324;7005524405;","The soil-precipitation feedback: A process study with a regional climate model",1999,"10.1175/1520-0442(1999)012<0722:tspfap>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0039613986&doi=10.1175%2f1520-0442%281999%29012%3c0722%3atspfap%3e2.0.co%3b2&partnerID=40&md5=a82545654da1685eba1929e07791f6aa","Month-long integrations with a regional climate model covering Europe and the Northern Atlantic are utilized to study the sensitivity of the summertime European precipitation climate with respect to the continental-scale soil moisture content. Experiments are conducted for July 1990 and 1993. For each of the two months, the control experiment with the initial soil water distribution derived from the operational ECMWF analysis is compared against two sensitivity experiments with dry and wet initial soil moisture distributions. The results demonstrate that summertime European precipitation climate in a belt ∼1000 km wide between the wet Atlantic and the dry Mediterranean climate heavily depends upon the soil moisture content. In this belt, changes in monthly mean precipitation amount to about half of the changes in mean evapotranspiration. Budget analysis of water substance over selected subdomains demonstrate that the simulated sensitivity cannot be interpreted with the classical recycling mechanism, that is, the surplus of precipitation that falls over wet (as compared to dry) soils does not directly derive from evapotranspiration. Rather, the surplus of precipitation primarily originates from water vapor extracted from the ambient atmospheric flow. Thus, the soil-precipitation feedback must rely on some indirect mechanism, whereby wet soils increase the efficiency of convective precipitation processes. In order to isolate the physical mechanisms underlying the soil-precipitation feedback, a detailed analysis including an investigation of the mean diurnal cycle throughout the integration period is performed. The key elements of the feedback are the following. First, wet soils (small Bowen ratios) imply the buildup of a comparatively shallow boundary layer. The surface fluxes of heat and moisture are thus concentrated into a comparatively small volume of air, leading to the buildup of high values of low-level moist entropy, thereby providing a source of convective instability. Second, the level of free convection is lowered in the wet experiment, thus facilitating the release of convective instability. Third, the net shortwave absorption at the soil decreases in the wet experiment (as a result of increased cloud cover), but this effect is overpowered by the decrease in net longwave emission (as a result of decreased emission, increased cloud backscatter, and increased water vapor greenhouse effect). Thus the net radiative energy flux is larger in the wet experiments, thereby increasing the moist entropy fluxes into the boundary layer. These three processes act in concert to increase the potential for convective activity."
"7202559581;7202155374;","Interpolation of surface radiative temperature measured from polar orbiting satellites to a diurnal cycle 1. Without clouds",1999,"10.1029/1998JD200005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608146&doi=10.1029%2f1998JD200005&partnerID=40&md5=7b4f7a2409bbfaa4bb4c4196f06425fb","The land surface skin temperature diurnal cycle (LSTD) is an important element of the climate system: This variable, however, cannot be directly obtained globally from polar orbiting satellites because such satellites only pass a given area twice per day and because their infrared channels cannot observe the surface when the sky is cloudy. To obtain the skin temperature diurnal cycle and fully utilize satellite measurements, we have designed an efficient algorithm that combines model results with satellite and surface-based observations and interpolates satellite twice-daily observations into the diurnal cycle. Climatological information from a climate model, CCM3/BATS, is used to determine a normalized shape (typical pattern) of the diurnal temperature for different latitudes, seasons, and vegetation types. The satellite observations, which are by themselves inadequate, are combined with the normalized modeled diurnal typical patterns to obtain the skin temperature diurnal cycle. The normalized typical patterns depend on the parameters of the diurnal insolation, such as sunrise, sunset, and peak times, and are also affected by the type of vegetation cover and soil moisture. The underlying physical foundation of this algorithm is that the diurnal cycle of temperature can be viewed as a composite of a daily average, diurnal periodic component, and random aperiodic component (noise). With the assumption that the noise can be ignored, the daily average can be inferred from satellite twice-per-day measurements and the periodic part can be obtained from modeled climatologies, providing a reasonable approach for estimation of the diurnal cycle of skin temperature. The general framework of the algorithm and its application for the clear-sky (cloud free) conditions are presented. This cloud-free version of algorithm is evaluated using FIFE and BOREAS field experiment surface observations. Regional tests over the Mississippi River basin have also been conducted using GOES-8 and AVHRR observations. Uncertainties of this cloud-free algorithm have been analyzed, indicating an accuracy of about 1-2 K for monthly cloud-free diurnal cycles at near-pixel resolution. Copyright 1999 by the American Geophysical Union."
"7005777274;","Prevalence of precipitation from warm-topped clouds over eastern Asia and the western Pacific",1999,"10.1175/1520-0442-12.1.220","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033045959&doi=10.1175%2f1520-0442-12.1.220&partnerID=40&md5=ffc6ba0de8253350881b4e62edea963b","Land and ship surface synoptic reports of nondrizzle intensity precipitation in progress were matched with 3596 nearly coincident full disk 4-km resolution infrared images from the GMS-5 geostationary satellite, covering 18 calendar months, in order to derive regional and seasonal estimates of the contribution of relatively warmtopped clouds to the total time in precipitation. Minimum infrared temperatures of 273 K or warmer were found to be associated with 20%-40% of the surface reports of nondrizzle precipitation over much of the ocean east of Australia during all four seasons. Similar or even larger fractions were found during December-March over parts of Indonesia, southern China, and the adjacent South China Sea. Although reports of precipitation of moderate or heavy intensity were found to be associated more often with colder cloud tops, there were still regions for which a substantial fraction of these reports were associated with relatively warm clouds. These results suggest at least a potential for significant regional and seasonal biases in satellite infrared or passive microwave scattering based estimates of global precipitation.Land and ship surface synoptic reports of nondrizzle intensity precipitation in progress were matched with 3596 nearly coincident full disk 4-km resolution infrared images from the GMS-5 geostationary satellite, covering 18 calendar months, in order to derive regional and seasonal estimates of the contribution of relatively warm-topped clouds to the total time in precipitation. Minimum infrared temperatures of 273 K or warmer were found to be associated with 20%-40% of the surface reports of nondrizzle precipitation over much of the ocean east of Australia during all four seasons. Similar or even larger fractions were found during December-March over parts of Indochina, southern China, and the adjacent South China Sea. Although reports of precipitation of moderate or heavy intensity were found to be associated more often with colder cloud tops, there were still regions for which a substantial fraction of these reports were associated with relatively warm clouds. These results suggest at least a potential for significant regional and seasonal biases in satellite infrared or passive microwave scattering based estimates of global precipitation."
"7203062717;7404653593;7402565232;7401559815;","Principal modes of climatological seasonal and intraseasonal variations of the Asian summer monsoon",1999,"10.1175/1520-0493(1999)127<0322:pmocsa>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032743404&doi=10.1175%2f1520-0493%281999%29127%3c0322%3apmocsa%3e2.0.co%3b2&partnerID=40&md5=d008d5640527e21c7dc258e5d6e8a1cc","Principal modes of climatological variation of the Asian summer monsoon are investigated. Data used in this study include the high cloud fraction produced by the International Satellite Cloud Climatology Project and sea level pressure, and 850-and 200-mb geopotential heights from ECMWF analysis for the five summers of 1985-89. It is shown that the seasonal evolution of the Asian summer monsoon is adequately described by a few leading EOFs. These EOFs capture the variations of regional rainbands over the East Asian and Indian regions. The first mode is characterized by an increase in large-scale cloud over India and the subtropical western Pacific until mid-August. The second mode depicts large-scale cloud variations associated with the East Asian rainband referred to as Mei Yu and Baiu. This mode is associated with the development of summer monsoon circulation: a low pressure system over the Asian continent and a subtropical high over the Pacific. The third eigenmode is characterized by zonal cloud bands from northern India, crossing the Korean peninsula to Japan, and dryness over the oceans in the south of cloud bands. This mode is related to the mature phase of Changma rainy season in Korea associated with the northward movement of cloud bands and circulation systems from the subtropical western Pacific. This mode appears as a first principal mode of climatological intraseasonal oscillation (CISO) over the entire Asian monsoon region. The CISO mode has a timescale of about 2 months. The northward moving CISO also appears in the 850-and 200-mb geopotential height fields as a first mode of each dataset. Based on the height variations of the CISO mode, it is suggested that the extratropical CISO during summer is related to a regional index cycle associated with the variation of north-south temperature gradient in East Asia."
"7003275940;7202346909;6507380941;36754096100;7102746335;","Multiple Doppler radar observation of tropical precipitation systems in JATMEX",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032645255&partnerID=40&md5=20c842edb89f49b1b287721743754df6","The Japan Australia Tropical Mesoscale Experiment (JATMEX) cooperative project focuses on understanding of the mesoscale lifecycle of tropical convection and squals, and their impacts on the environmental atmosphere. As part of this research, data collection was carried out in Darwin using mainly four Doppler radars. Using the data obtained, it was possible to investigate the detailed dynamical structure of convective precipitation systems and their time evolution."
"57196216153;6602002299;7003753838;","Characterisation of raindrop size distribution in Mediterranean climate: analysis of the variations on the Z-R relationship",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032645247&partnerID=40&md5=003671eb9336c6c09e4db9cfc67df640","This study attempts to determine the drop size distributions (DSDs) observed in Mediterranean climate. The study uses DSD measured at the ground level using an Optical Spectro Pluviometer (OSP) at Marseille. An event by event analysis of the DSDs is performed following the methodology proposed by Sempere-Torres et al. The fitted DSDs shape and parameters variations are compared against an estimate of their variance obtained by the boot-strap method. This comparison suggests that in Marseille, storm raindrop populations do not always fit the Marshall and Palmer DSD although an extended exponential DSD is well adapted."
"7005578774;","Conceptual framework for changes of extremes of the hydrological cycle with climate change",1999,"10.1023/A:1005488920935","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032775782&doi=10.1023%2fA%3a1005488920935&partnerID=40&md5=c8527d232e0e68c41cfe7ec77722b5c4","A physically based conceptual framework is put forward that explains why an increase in heavy precipitation events should be a primary manifestation of the climate change that accompanies increases in greenhouse gases in the atmosphere. Increased concentrations of greenhouse gases in the atmosphere increase downwelling infrared radiation, and this global heating at the surface not only acts to increase temperatures but also increases evaporation which enhances the atmospheric moisture content. Consequently all weather systems, ranging from individual clouds and thunderstorms to extratropical cyclones, which feed on the available moisture through storm-scale moisture convergence, are likely to produce correspondingly enhanced precipitation rates. Increases in heavy rainfall at the expense of more moderate rainfall are the consequence along with increased runoff and risk of flooding. However, because of constraints in the surface energy budget, there are also implications for the frequency and/or efficiency of precipitation. It follows that increased attention should be given to trends in atmospheric moisture content, and datasets on hourly precipitation rates and frequency need to be developed and analyzed as well as total accumulation."
"7403225569;7501962943;57197229961;57208725580;","Study on severe winter storm in Taiwan in 1998",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032644781&partnerID=40&md5=26ee4ab6a0091067c68b6da6f8613c1d","During 18-20 February 1998, severe weather including heavy rain, hail and unconfirmed tornadoes occurred in the west side of Taiwan. These three days' severe weather event was quite unusual. This study documents this unusual event and determines the environmental condition for the occurrence of this event. In particular, the weather phenomena in Taiwan are analyzed and the PSU/NCAR MM5 model is used to diagnose the environmental condition for producing severe weather."
"7403247998;","The relationship among precipitation, cloud-top temperature, and precipitable water over the tropics",1999,"10.1175/1520-0442(1999)012<2503:trapct>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033172558&doi=10.1175%2f1520-0442%281999%29012%3c2503%3atrapct%3e2.0.co%3b2&partnerID=40&md5=28eb90672f900ba4d04547f0f35c83a1","The relationship of monthly precipitation P to precipitable water w and cloud-top temperature as represented by the Geostationary Operational Environmental Satellite (GOES) Precipitation Index (GPI) is obtained over tropical land, coast, and ocean: P = exp[a1(w - a2)] GPI, where coefficients a1 and a2 are determined using one year of the Global Precipitation Climatology Project (GPCP) monthly rain gauge data and then independently tested using four other years of gauge data. This algorithm, over land, gives more accurate precipitation estimates than are obtained using the cloud-top temperature alone (i.e., GPI) and is as accurate as the state-of-the-art multisatellite algorithm (MS) from GPCP. Over coastal and oceanic regions, this algorithm has a smaller bias in precipitation estimation than GPI but has the same correlation coefficient with gauge data as GPI. Compared with MS, it has a much smaller bias but larger mean absolute deviation. Evaluation using the Pacific atoll-island gauge data also shows that this algorithm can reproduce well the observed meridional distribution of precipitation across the ITCZ and SPCZ near the date line. This algorithm is then used to produce a five-year (January 1988-December 1992) 2.5°X 2.5°integrated dataset of precipitation and precipitable water between 40°N and 40°S for climate model evaluation. The small bias of this algorithm (particularly over ocean) also suggests that it would be a good data source for precipitation merging algorithms."
"7003979342;7102403008;7003931528;7005219614;7004920873;","Transient climate change simulations with a coupled atmosphere-ocean GCM including the tropospheric sulfur cycle",1999,"10.1175/1520-0442(1999)012<3004:TCCSWA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033208511&doi=10.1175%2f1520-0442%281999%29012%3c3004%3aTCCSWA%3e2.0.CO%3b2&partnerID=40&md5=6821bf02074d390777540340176da151","The time-dependent climate response to changing concentration of greenhouse gases and sulfate aerosols is studied using a coupled general circulation model of the atmosphere and the ocean (ECHAM4/OPYC3). The concentration of the well-mixed greenhouse gases like CO2, CH4, N2O, and CFCs are prescribed for the past (1860-1990) and projected into the future according to International Panel on Climate Change (IPCC) scenario IS92a. In addition, the space-time distribution of tropospheric ozone is prescribed, and the tropospheric sulfur cycle is calculated within the coupled model using sulfur emissions of the past and projected into the future (IS92a). The radiative impact of the aerosols is considered via both the direct and the indirect (i.e., through cloud albedo) effect. It is shown that the simulated trend in sulfate deposition since the end of the last century is broadly consistent with ice core measurements, and the calculated radiative forcings from preindustrial to present time are within the uncertainty range estimated by IPCC. Three climate perturbation experiments are performed, applying different forcing mechanisms, and the results are compared with those obtained from a 300-yr unforced control experiment. As in previous experiments, the climate response is similar, but weaker, if aerosol effects are included in addition to greenhouse gases. One notable difference to previous experiments is that the strength of the Indian summer monsoon is not fundamentally affected by the inclusion of aerosol effects. Although the monsoon is damped compared to a greenhouse gas only experiment, it is still more vigorous than in the control experiment. This different behavior, compared to previous studies, is the result of the different land-sea distribution of aerosol forcing. Somewhat unexpected, the intensity of the global hydrological cycle becomes weaker in a warmer climate if both direct and indirect aerosol effects are included in addition to the greenhouse gases. This can be related to anomalous net radiative cooling of the earth's surface through aerosols, which is balanced by reduced turbulent transfer of both sensible and latent heat from the surface to the atmosphere.The time-dependent climate response to changing concentrations of greenhouse gases and sulfate aerosols is studied using a coupled general circulation model of the atmosphere and the ocean (ECHAM4/OPYC3). The concentrations of the well-mixed greenhouse gases like CO2, CH4, N2O, and CFCs are prescribed for the past (1860-1990) and projected into the future according to International Panel on Climate Change (IPCC) scenario IS92a. In addition, the space-time distribution of tropospheric ozone is prescribed, and the tropospheric sulfur cycle is calculated within the coupled model using sulfur emissions of the past and projected into the future (IS92a). The radiative impact of the aerosols is considered via both the direct and the indirect (i.e., through cloud albedo) effect. It is shown that the simulated trend in sulfate deposition since the end of the last century is broadly consistent with ice core measurements, and the calculated radiative forcings from preindustrial to present time are within the uncertainty range estimated by IPCC. Three climate perturbation experiments are performed, applying different forcing mechanisms, and the results are compared with those obtained from a 300-yr unforced control experiment. As in previous experiments, the climate response is similar, but weaker, if aerosol effects are included in addition to greenhouse gases. One notable difference to previous experiments is that the strength of the Indian summer monsoon is not fundamentally affected by the inclusion of aerosol effects. Although the monsoon is damped compared to a greenhouse gas only experiment, it is still more vigorous than in the control experiment. This different behavior, compared to previous studies, is the result of the different land-sea distribution of aerosol forcing. Somewhat unexpected, the intensity of the global hydrological cycle becomes weaker in a warmer climate if both direct and indirect aerosol effects are included in addition to the greenhouse gases. This can be related to anomalous net radiative cooling of the earth's surface through aerosols, which is balanced by reduced turbulent transfer of both sensible and latent heat from the surface to the atmosphere."
"7005365571;7402739097;7006577693;55678879300;7202899330;7102953444;","Surface radiation fluxes in transient climate simulations",1999,"10.1016/S0921-8181(98)00059-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032933926&doi=10.1016%2fS0921-8181%2898%2900059-9&partnerID=40&md5=81cfa4fba72d80af208ef6d5c28b4344","Transient CO2 experiments from five coupled climate models, in which the CO2 concentration increases at rates of 0.6-1.1% per annum for periods of 75-200 years, are used to document the responses of surface radiation fluxes, and associated atmospheric properties, to the CO2 increase. In all five models, the responses of global surface temperature and column water vapour are non-linear and fairly tightly constrained. Thus, global warming lies between 1.9 and 2.7 K at doubled, and between 3.1 and 4.1 K at tripled, CO2, whilst column water vapour increases by between 3.5 and 4.5 mm at doubled, and between 7 and 8 mm at tripled, CO2. Global cloud fraction tends to decrease by 1-2% out to tripled CO2, mainly the result of decreases in low cloud. Global increases in column water, and differences m these increases between models, are mainly determined by the warming of the tropical oceans relative to the middle and high latitudes; these links are emphasised in the zonal profiles of warming and column water vapour increase, with strong water vapour maxima in the tropics. In all models the all-sky shortwave flux to the surface S↓ (global, annual average) changes by less than 5 W m-2 out to tripled CO2, in some cases being essentially invariant in time. In contrast, the longwave flux to the surface L↓ increases significantly, by 25 W m-2 typically at tripled CO2. The variations of S↓ and L↓ (clear-sky and all-sky fluxes) with increase in CO2 concentration are generally non-linear, reflecting the effects of ocean thermal inertia, but as functions of global warming are close to linear in all five models. This is best illustrated for the clear-sky downwelling fluxes, and the net radiation. Regionally, as illustrated in zonal profiles and global distributions, greatest changes in both S↓ and L↓ are the result primarily of local maxima in warming and column water vapour increases."
"7501828935;57207592379;","Sensitivity analysis of a moist ID Eulerian cloud model using automatic differentiation",1999,"10.1175/1520-0493(1999)127<2180:SAOAME>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033384912&doi=10.1175%2f1520-0493%281999%29127%3c2180%3aSAOAME%3e2.0.CO%3b2&partnerID=40&md5=a008240802e64c0e96f4a089242f5f0a","An automatic differentiation tool (ADIFOR) is applied to a warm-rain, time-dependent ID cloud model to study the influence of input parameter variability, including that associated with the initial state as well as physical and computational parameters, on the dynamical evolution of a deep convective storm. Storm dynamics are found to be controlled principally by changes in model initial states below 2 km; once perturbed, each grid variable in the model plays its own unique role in determining the dynamical evolution of the storm. Among all model-dependent variables, the low-level temperature field has the greatest impact on precipitation, followed by the water vapor field. Mass field perturbations inserted at upper levels induce prominent oscillations in the wind field, whereas a comparable wind perturbation has a negligible effect on the thermodynamic field. However, the wind field does influence the precipitation in a more complex way than does the thermodynamic field, principally via changes in time evolution. The simulated storm responds to variations in three physical parameters (the autoconversion/accretion rate, cloud radius, and lateral eddy exchange coefficient) largely as expected, with the relative importance of each, quantified via a relative sensitivity analysis, being a strong function of the particular stage in the storm's life cycle. © 1999 American Meteorological Society."
"7201844203;","Atmospheric solar heating in minor absorption bands",1999,"10.3319/TAO.1999.10.3.511(A)","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033460465&doi=10.3319%2fTAO.1999.10.3.511%28A%29&partnerID=40&md5=0f45c39868903c2510b3b505f6c83829","Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge amount of time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284 cm-1 to 25000 cm-1, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral-and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by ∼10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models."
"7006592026;57202826644;","Introduction to special section: Regional climate modeling revisited",1999,"10.1029/98JD02072","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000377434&doi=10.1029%2f98JD02072&partnerID=40&md5=c5213f15ed1e3f31dcb2e79cb43624f9","This paper provides an introduction to the special issue of the Journal of Geophysical Research on ""New Developments and Applications With the NCAR Regional Climate Model (RegCM)."" In the first part of the paper we revisit and discuss outstanding issues in regional climate modeling in view of the progress achieved in this area of research during the last decade. We discuss issues of simulation length, spin-up, model physics, domain and resolution, lateral boundary conditions, multiple and two way nesting, and variable resolution approaches. In the second part we introduce the papers included in this issue. Among the primary model developments that occurred in the last few years are inclusions of the radiative transfer package and cumulus convection scheme from the National Center for Atmospheric Research (NCAR) global model CCM3, a simplified explicit moisture scheme including direct interaction with cloud radiation, testing of a variable resolution model configuration, improvements in the coupled lake model, and interactive coupling with radiatively active atmospheric aerosols. The papers in the issue illustrate a wide range of applications over different regions, such as the United States, East Asia, central Asia, eastern Africa. The main model limitations and areas in need of improvement are indicated. Copyright 1999 by the American Geophysical Union."
"7409386386;7007085057;6603073692;14022203400;","Sensitivity to large-scale environmental fields of the relaxed Arakawa-Schubert parameterization in the NASA GEOS-1 GCM",1999,"10.1175/1520-0493(1999)127<2359:STLSEF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033368932&doi=10.1175%2f1520-0493%281999%29127%3c2359%3aSTLSEF%3e2.0.CO%3b2&partnerID=40&md5=66a04a0b7a4c257aa74768de45c842a1","An adjoint sensitivity analysis of the relaxed Arakawa-Schubert scheme in the National Aeronautics and Space Administration GEOS-1 GCM with respect to perturbations in large-scale environmental fields was conducted. The response functions were defined as measures of the strength of convective cloud precipitation, the cloud-induced heating and drying (moistening) in both the instantaneous and time-integrated sense. The roles of different variables in producing variations on the response functions were evaluated and the most sensitive vertical levels of the perturbations were identified with the gradient provided by the adjoint model. It was found that the potential temperature perturbations had significant impact on all the response functionals analyzed, especially on the convective precipitation. The perturbations at subcloud layers and at midtroposphere from 500 to 600 hPa were found to be the most influential. The impact from the moisture fields was most significant on cloud heating and drying effects and the strongest influence came from the subcloud layers. The moisture perturbations at midtroposphere also significantly influenced the cloud drying (moistening) effect. On the other hand, the cloud-induced heating and drying at levels between 400 and 600 hPa felt the strongest impact from perturbations in large-scale fields. The influence of the perturbations in the wind field was weaker but still provided reasonable sensitivity patterns. The time-integrated and instantaneous sensitivities for the same response differ only in magnitude but not in the general distributions. The impact of large-scale condensation and reevaporation on the sensitivity was also evaluated. Their effect was significant at the midtropospheric level and they enhanced the model sensitivity to perturbations in temperature and moisture fields. The sensitivity analysis results obtained indicated that accurate gridscale vertical profile of temperature and moisture, especially at subcloud layers and midtroposphere between 500 and 600 hPa were essential for the accurate evaluation of the cumulus cloud effects. The implications of the results of this work for variational data assimilation were also discussed."
"7004390586;7006417494;","A land-atmosphere interaction theory for the tropical deforestation problem",1999,"10.1175/1520-0442(1999)012<0857:alaitf>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033102104&doi=10.1175%2f1520-0442%281999%29012%3c0857%3aalaitf%3e2.0.co%3b2&partnerID=40&md5=1f33f6285406f02c755c8f1c8986eed2","A theoretical framework is developed in understanding the mechanisms and processes determining the response of the land-atmosphere system to tropical deforestation. The analytical approach is made possible by simplifications in the vertical from the quasi-equilibrium moist convective closure, and in the horizontal from the dynamical temperature homogenization process. The theory emphasizes the energy and water balance. It highlights the interaction among processes of moist convection, cloud, radiation, and surface hydrology while each individual process is simplified. The zero surface energy flux condition, due to the small heat capacity of land, makes land-atmosphere interaction distinctly different from ocean-atmosphere interaction. This imposes a constraint on the sensitivity to the details of surface energy partitioning. Consequently, land surface temperature is largely a response to the energy and water balance, rather than a forcing as in the case of sea surface temperature. Results from a wet-season surface albedo change case compare well with a recent RCCM2/BATS simulation, with the theory depicting the mechanisms and the roles of the intertwining processes. The precipitation has a significant decrease, initiated by ground radiative forcing as increased surface albedo reflects more solar radiation into space. A positive feedback by moisture convergence is essential for this tendency, with another positive feedback from reduced evaporation providing further enhancement. These are opposed by a negative feedback due to the reduced magnitude of negative cloud radiative forcing as cloud cover decreases. This sheds light on the higher sensitivity in some GCM studies with prescribed clouds. The cloud radiative forcing also has a negative feedback on the initial cooling tendency in ground temperature. Together with reduced evaporation, this leads to little change in the ground temperature. Sensitivities of precipitation and ground temperature changes to individual processes are found to depend on the reference state parameter values, implying a sensitivity of anomaly response to simulated climatology for GCMs. The analysis here also serves as an example of the tight coupling between convection, large-scale atmospheric dynamics, and land processes in the tropical land-atmosphere system."
"7004286811;","Ceres: The start of the next generation of radiation measurements",1999,"10.1016/S0273-1177(99)00354-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033387329&doi=10.1016%2fS0273-1177%2899%2900354-3&partnerID=40&md5=406959a9d26255fb9e2237cb280f941c","This paper describes current state of the investigation of Clouds and the Earth's Radiant Energy System (CERES), which had its first instrument launched on the Tropical Rainfall Measuring Mission (TRMM) from Japan in late November 1998. This instrument performed extremely well during its first six months in orbit. The ERBE-like data products from the CERES instrument on TRMM are being archived, so that geolocated radiances are already available for scientific research, about six months after launch. This paper also describes some of the validation work the CERES Team has undertaken and identifies differences between ERBE data and CERES. Because of the complexity of the measurement process, several factors must be considered in dealing with the question of whether these differences are the result of changes between the ERBE and CERES measurements or are real changes in the radiation budget. Based on this work, the CERES investigation appears poised to provide a major improvement in our understanding of the interaction between clouds, radiation, and climate."
"7406354393;7005087624;57202803751;","Assimilating TOVS humidity into the GEOS-2 data assimilation system",1999,"10.1175/1520-0442(1999)012<2983:ATHITG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033208516&doi=10.1175%2f1520-0442%281999%29012%3c2983%3aATHITG%3e2.0.CO%3b2&partnerID=40&md5=e41544818dc0edf0b697c064de2a4c9e","The humidity data retrieved from the TIROS Operational Vertical Sounder (TOVS) measurements is assimilated into the Goddard Earth Observing System (GEOS) data assimilation system. The study focuses on the impact of the TOVS humidity on assimilated humidity, precipitation, clouds, and radiation. The GEOS assimilation system utilizes the TOVS humidity effectively at levels below 300 mb, while the net impact on the 300-mb humidity is much less. It has been demonstrated that the impact results from direct and indirect effects. The direct effect is the analysis increment introduced by the humidity data, which draws the assimilated humidity toward the data. The indirect effect is realized through the interactions of humidity with physical processes, mainly with moist convection. The indirect effect is often opposite to the direct effect in the current assimilation system. The direct effect is dominant in the lower and middle troposphere while in the upper troposphere the indirect effect is more important. The impact of the TOVS humidity on the GEOS precipitation, clouds, and radiation is also significant due to strong interactions with convection and other physical processes. There is clear evidence indicating that tuning of physical parameterizations explicitly in the data assimilation mode is necessary for optimal use of the TOVS data in the assimilation system.The humidity data retrieved from the TIROS Operational Vertical Sounder (TOVS) measurements is assimilated into the Goddard Earth Observing System (GEOS) data assimilation system. The study focuses on the impact of the TOVS humidity on assimilated humidity, precipitation, clouds, and radiation. The GEOS assimilation system utilizes the TOVS humidity effectively at levels below 300 mb, while the net impact on the 300-mb humidity is much less. It has been demonstrated that the impact results from direct and indirect effects. The direct effect is the analysis increment introduced by the humidity data, which draws the assimilated humidity toward the data. The indirect effect is realized through the interactions of humidity with physical processes, mainly with moist convection. The indirect effect is often opposite to the direct effect in the current assimilation system. The direct effect is dominant in the lower and middle troposphere while in the upper troposphere the indirect effect is more important. The impact of the TOVS humidity on the GEOS precipitation, clouds, and radiation is also significant due to strong interactions with convection and other physical processes. There is clear evidence indicating that tuning of physical parameterizations explicitly in the data assimilation mode is necessary for optimal use of the TOVS data in the assimilation system."
"7006550762;7004935827;7006224475;","Simulated time-dependent climate response to solar radiative forcing since 1600",1999,"10.1029/1998JD200020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608193&doi=10.1029%2f1998JD200020&partnerID=40&md5=607b4b0630f68ed0051c0a3917b20a6c","Estimated solar irradiance variations since 1500 have been used to force the GISS atmospheric GCM coupled to a mixed layer ""q-flux"" ocean with heat diffusion through the bottom of the mixed layer. The goal is to assess solar-induced climate change in preindustrial and postindustrial epochs. Six simulations and control runs were made to test the effects of different initial conditions, estimates of initial solar forcing conditions, and ocean heat uptake. The results show that an estimated solar forcing increase of 0.25% accounts for a 0.45°C temperature increase since 1600 and an increase of about 0.2°C over the past 100 years. Global surface temperatures lag solar fluctuations by up to 10 years; the lag is greater over the oceans and so is the correlation due to reduced noise. With only a mixed layer ocean the phase lag is 5 years less. Solar forcing and water vapor feedback each directly account for 35% of the temperature response, with cloud cover changes contributing 20% and sea ice/snow cover 10%. Uncertainty in the initial radiation imbalance or solar forcing affects the surface temperatures for 60-90 years. Modeled and observed periodicities show dominance of long-period forcing (&gt;50 years), as provided by the solar input in these experiments. Tropical temperatures correlate best with solar forcing, due to the influence of water vapor feedback, especially at these multidecadal periods. Sea ice and extratropical temperatures have less long-period power, while high-frequency fluctuations dominate simulated cloud cover variations, which are relatively independent of solar forcing changes. Global and extratropical precipitation increase as the climate warms, but not low and subtropical precipitation, due to conflicting influences of absolute temperature and temperature gradient changes. Solar forcing by itself was not sufficient to produce the rapid warming during the last several decades. A comparison experiment varying trace gas forcing suggests that if the solar estimate is correct, then negative forcing by tropospheric aerosols (and perhaps volcanoes, ozone, and land use changes) has been about -1.2 W m-2 since 1700, implying approximately equal contribution from direct and indirect tropospheric aerosol effects. Copyright 1999 by the American Geophysical Union."
"7202746102;7003597653;55869652000;7201706787;7004384155;6602176524;55837993200;6701481007;6602504047;","Characteristics of the TOVS pathfinder path-B dataset",1999,"10.1175/1520-0477(1999)080<2679:COTTPP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000443504&doi=10.1175%2f1520-0477%281999%29080%3c2679%3aCOTTPP%3e2.0.CO%3b2&partnerID=40&md5=23dd51033b94e815bd4edeb75bd8c3e2","From 1979 to present, sensors aboard the NOAA series of polar meteorological satellites have provided continuous measurements of the earth's surface and atmosphere. One of these sensors, the TIROS-N Operational Vertical Sounder (TOVS), observes earth-emitted radiation in 27 wavelength bands within the infrared and microwave portions of the spectrum, thereby creating a valuable resource for studying the climate of our planet. The NOAA-NASA Pathfinder program was conceived to make these data more readily accessible to the community in the form of processed geophysical variables. The Atmospheric Radiation Analysis group at the Laboratoire de Météorologie Dynamique of the Centre National de la Recherche Scientifique of France was selected to process TOVS data into climate products (PathB). The Improved Initialization Inversion (3I) retrieval algorithm is used to compute these products from the satellite-observed radiances. The processing technique ensures internal coherence and minimizes both observational and computational biases. Products are at a 1° × 1° latitude-longitude grid and include atmospheric temperature profiles (up to 10 hPa); total precipitable water vapor and content above four levels up to 300 hPa; surface skin temperature; and cloud properties (amount, type, and cloud-top pressure and temperature). The information is archived as 1-day, 5-day, and monthly means on the entire globe; A.M. and P.M. products for each satellite are stored separately. Eight years have been processed to date, and processing continues at the rate of approximately two satellite-months per day of computer time. Quality assessment studies are presented. They consist of comparisons to conventional meteorological data and to other remote sensing datasets."
"57206128696;7102774997;","The effect of climate change on floods in British Columbia",1999,"10.2166/nh.1999.0013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033367785&doi=10.2166%2fnh.1999.0013&partnerID=40&md5=764349bf2fe3ff913ffb949a9d6cc207","A hydrological modelling of the flood response of two watersheds to climate change are presented. The two study watersheds are the Upper Campbell and the Illecillewaet watersheds located in British Columbia. The first watershed is a maritime watershed located on the east slopes of the Vancouver Island mountains whereas the second watershed is located in the Selkirk Mountains in Eastern British Columbia. The Canadian Climate Centre General Circulation Model (CCC GCM) has been used for the estimation of the effect of the climate change on meteorological parameters. The CCC GCM is a steady state model and the output of the 1991 run has been used. In addition to the changes in the amounts of precipitation and temperature usually assumed in hydrological climate change studies, other meteorological and climatic parameters are also considered; specifically, the effect of climate on the spatial distribution of precipitation with elevation, and also on cloud cover, glaciers, vegetation distribution, vegetation biomass production, and plant physiology. The results showed that the mean annual temperature in the two watersheds could increase by more than 3°C and the annual basin-wide precipitation could increase by 7.5% in Upper Campbell watershed and by about 17% in the Illecillewaet watershed. As a result, the mean annual runoff will increase by 7.5% in the Upper Campbell watershed and 21% in the Illecillewaet basin. For the study of floods, nine flood parameters have been investigated, the total number of flood episodes, the flood days per year, the duration of flood events, the annual flood volume, the mean flood flow, the mean flood peak, the annual maximum flood peak, the day of occurrence of the centroid of flood volume, and the day of occurrence of annual maximum flood peak. These nine parameters were extracted from the hydrographs of the two study watersheds using the double long-term mean daily flow. The study showed that, under the climate change scenario, the floods in the maritime Upper Campbell watershed would increase, on average, in magnitude by 14%, in volume by 94%, in frequency by 11%, and duration by 44%. The timing of the floods would remain almost unchanged, and the centroid of flood volume would shift earlier by only 2 days. In contrast, in the interior mountain Illecillewaet watershed, the floods would decrease, on average, in magnitude by 7%, in volume by 38%, and frequency by 23%. The duration of flood events, under the altered climate scenario, would remain, essentially, unchanged increasingly by only 2.6%. Also, the study showed that in the Illecillewaet watershed the largest change between the altered climate and the present climate scenarios would be the timing of floods since the centroid of flood volume would occur 20 days earlier. The above changes in the flood response of the two study watersheds can be explained by the changes in the distribution and form of annual precipitation. These results indicate that different management procedures will be needed to minimize the effects of climate change on the flooding of the two climatically different watersheds and the regions that they represent."
"7006548794;","The atmosphere of the moon",1999,"10.1023/a:1017032419247","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034766762&doi=10.1023%2fa%3a1017032419247&partnerID=40&md5=601eb07a14f49677c55f907cc28c01e4","The possible existence of a lunar atmosphere has both fascinated and challenged astronomers for hundreds of years. Galileo searched for evidence of clouds, and Kepler imagined an Earth-like climate. Landings during the Apollo era brought instruments that measured a weak atmospheric pressure. Decades later, new spectrographic and imaging instruments detected sodium and potassium gas that extended to surprisingly large distances, making the Moon's gaseous environment appear as comet-like. The sources of the lunar atmosphere involve the impact of sunlight, solar wind plasma and meteors upon the surface to release atoms and perhaps molecules. Solar radiation and the gravitational influence of the Earth play dramatic roles in the subsequent evolution of the lunar atmosphere."
"55573647400;56269065000;","Monthly mean diurnal cycles in surface temperatures over land for global climate studies",1999,"10.1175/1520-0442(1999)012<1900:MMDCIS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032732752&doi=10.1175%2f1520-0442%281999%29012%3c1900%3aMMDCIS%3e2.0.CO%3b2&partnerID=40&md5=8554b7e2bcb7cd04528373cddabb0434","Monthly mean diurnal cycles (MDCs) of surface temperatures over land, represented in 3-h universal time intervals, have been analyzed. Satellite near-global data from the International Satellite Cloud Climatology Project (ISCCP) with a (280 km)2 resolution (C-2 product) are available for seven individual years and as a climatology derived thereof. Surface 19-yr climatologies on ground and air temperatures, separately for all-sky and clear-sky conditions, matched with ISCCP data, are employed to better understand satellite-derived MDCs. The MDCs have been converted to local solar time, refined to a regular 1-h time grid using cubic splines, and subjected to principal component analysis. The first two modes approximate MDCs in air and ground-satellite temperatures with rmse's of about σ = 0.5°and 1°C, respectively, and these accuracies are improved by 20%-35% if the third mode is added. This suggests that two to three temperature measurements during the day allow reconstruction of the full MDC. In the case of two modes, optimal observation times are close to the occurrence of minimum and maximum temperatures, T(min) and T(max). The authors provide an empirical algorithm for reconstructing the full MDC using T(min) and T(max), and estimate its accuracy. In the analyzed match-up dataset, the statistical structure of ground temperature for all-sky conditions most closely resembles that of the ISCCP derived temperature. The results are potentially useful for climate- and global-scale studies and applications.Monthly mean diurnal cycles (MDCs) of surface temperatures over land, represented in 3-h universal time intervals, have been analyzed. Satellite near-global data from the International Satellite Cloud Climatology Project (ISCCP) with a (280 km)2 resolution (C-2 product) are available for seven individual years and as a climatology derived thereof. Surface 19-yr climatologies on ground and air temperatures, separately for all-sky and clear-sky conditions, matched with the ISCCP data, are employed to better understand satellite-derived MDCs. The MDCs have been converted to local solar time, refined to a regular 1-h time grid using cubic splines, and subjected to principal component analysis. The first two modes approximate MDCs in air and ground-satellite temperatures with rmse's of about σ = 0.5° and 1 °C, respectively, and these accuracies are improved by 20%-35% if the third mode is added. This suggests that two to three temperature measurements during the day allow reconstruction of the full MDC. In the case of two modes, optimal observation times are close to the occurrence of minimum and maximum temperatures, Tmin and Tmax. The authors provide an empirical algorithm for reconstructing the full MDC using Tmin and Tmax, and estimate its accuracy. In the analyzed match-up dataset, the statistical structure of ground temperature for all-sky conditions most closely resembles that of the ISCCP derived temperature. The results are potentially useful for climate- and global-scale studies and applications."
"35584879800;","Solar radiation climate in Sweden",1999,"10.1016/S1464-1909(98)00050-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032869923&doi=10.1016%2fS1464-1909%2898%2900050-1&partnerID=40&md5=fc9c636c3e9942a0bc2da66830362c0e","Since 1983 a Swedish network of 12 solar radiation stations, measuring global radiation, G, and direct normal irradiance, E(N), is operated by SMHI. All stations are sited within the BALTEX area. During the fifteen years 1983-1997, for which a homogeneous radiation database has been built up, some clear features in the radiation climate show up. The largest difference in G on annular basis is between the stations Visby, located on the island of Gotland in the Baltic Sea, and Kiruna, the northernmost station. The mean annual total of G in Kiruna (2822 MJm-2) is 25% less than in Visby (3758 MJm-2). This is due to both latitudinal effects and differing cloud conditions. The effect of different cloudiness is clearly seen when comparing the stations Vaxjo and Visby, which are only separated by 0.74°in latitude. At the cloudier site in Vaxjo, G is on the average 12 % less than in Visby. At all stations there is a large year to year variation of 15 %, or more. During the period analysed there is a clear increasing trend in both G, E(N) and duration of bright sunshine at all stations. The trend in G averaged over all stations is + 7.2%/decade. This is mainly caused by decreasing cloudiness, especially during the summer months. Taking the atmospheric water vapour into account, the Angstrom turbidity coefficient, β, have been estimated from the measurements of E(N). Mean values of β during 1983-1997 are 0.082 in Lund (station with highest turbidity) and 0.056 in Kiruna (station with lowest turbidity). These values are strongly affected, approximately to the same extent, by the major volcanic eruptions of El Chichon and Mt. Pinatubo."
"7402215419;7404362679;7004303368;24435043300;","The prospect for remote sensing of cirrus clouds with a submillimeter-wave spectrometer",1999,"10.1175/1520-0450(1999)038<0514:TPFRSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032820654&doi=10.1175%2f1520-0450%281999%29038%3c0514%3aTPFRSO%3e2.0.CO%3b2&partnerID=40&md5=6294c10e8d969b5561c6f8bbb2824e4b","Given the substantial radiative effects of cirrus clouds and the need to validate cirrus cloud mass in climate models, it is important to measure the global distribution of cirrus properties with satellite remote sensing. Existing cirrus remote sensing techniques, such as solar reflectance methods, measure cirrus ice water path (IWP) rather indirectly and with limited accuracy. Submillimeter-wave radiometry is an independent method of cirrus remote sensing based on ice particles scattering the upwelling radiance emitted by the lower atmosphere. A new aircraft instrument, the Far Infrared Sensor for Cirrus (FIRSC), is described. The FIRSC employs a Fourier Transform Spectrometer (FTS), which measures the upwelling radiance across the whole submillimeter region (0.1-1.0-mm wavelength). This wide spectral coverage gives high sensitivity to most cirrus particle sizes and allows accurate determination of the characteristic particle size. Radiative transfer modeling is performed to analyze the capabilities of the submillimeter FTS technique. A linear inversion analysis is done to show that cirrus IWP, particle size, and upper-tropospheric temperature and water vapor may be accurately measured. A nonlinear statistical algorithm is developed using a database of 20 000 spectra simulated by randomly varying most relevant cirrus and atmospheric parameters. An empirical orthogonal function analysis reduces the 500-point spectrum (20-70 cm-1) to 15 ""pseudo-channels"" that are then input to a neural network to retrieve cirrus IWP and median particle diameter. A Monte Carlo accuracy study is performed with simulated spectra having realistic noise. The retrieval errors are low for IWP (rms less than a factor of 1.5) and for particle sizes (rms less than 30%) for IWP greater than 5 g m-2 and a wide range of median particle sizes. This detailed modeling indicates that there is good potential to accurately measure cirrus properties with a submillimeter FTS."
"6701773543;7004131981;6603478823;6602806615;7004607037;","Prediction of global irradiance on inclined surfaces from horizontal global irradiance",1999,"10.1016/S0360-5442(99)00025-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033363920&doi=10.1016%2fS0360-5442%2899%2900025-0&partnerID=40&md5=cd166d5301a7067b199a9897d0b1761a","Knowledge of the radiation components incoming at a surface is required in energy balance studies, technological applications such as renewable energy and in local and large-scale climate studies. Experimental data of global irradiance on inclined planes recorded at Granada (Spain, 37.08°N, 3.57°W) have been used in order to study the pattern of the angular distribution of global irradiance. We have modelled the global irradiance angular distribution, employing horizontal global irradiance as the only radiometric input, and geometric information. We have obtained good results (root mean square deviation about 5%), except for surfaces affected by artificial horizon effects, which are not allowed for in this new model. The Skyscan'834 data set has also been used in order to test the model under completely different conditions from those in Granada, with respect to the amount of cloud, local peculiarities, experimental design and instrumentation. The results prove the validity of our model, even when compared with the Perez et al. model. The model offers a reliable tool for use when solar radiance data are scarce or limited to global horizontal irradiance."
"7202803069;7006133602;","A simple method to retrieve 3-hourly estimates of global tropical and subtropical precipitation from International Satellite Cloud Climatology Program (ISCCP) D1 data",1999,"10.1175/1520-0426(1999)016<0146:ASMTRH>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032756804&doi=10.1175%2f1520-0426%281999%29016%3c0146%3aASMTRH%3e2.0.CO%3b2&partnerID=40&md5=947bd5b462c9e51906eee33626e61176","Algorithms to estimate rainfall from passive microwave or optical data from polar-orbiting satellites are limited by poor temporal sampling and are best suited to produce estimates integrated over periods of one month or more. There are numerous applications in the atmospheric sciences in which rainfall estimates are required at a much greater frequency. These can be derived from geostationary satellite infrared data, but currently no global archive of such products exists. This paper presents a simple technique to reconstruct Geostationary Operational Environmental Satellite Precipitation Index (GPI) estimates of rainfall over the global Tropics and subtropics at 3-hourly, 2.5°resolution from cloud-top temperature statistics contained in the extensive International Satellite Cloud Climatology Project D1 dataset. It is shown that the Reconstructed GPI (RGPI) estimates correlate very strongly with the GPI and have minimal bias, irrespective of the integration period selected or the underlying surface type. Comparison with the independent NASA WetNet PIP-3 surface rainfall validation data shows that the RGPI estimates of rainfall composited over monthly periods match the validation data with accuracy very similar to that of the GPI and are comparable to many passive microwave algorithms. Both the RGPI and GPI estimates of rainfall match the validation data more closely over the tropical Pacific Ocean than over the tropical and subtropical land masses where a positive bias is apparent. With 3-hourly temporal resolution, the RGPI represents a useful new resource for climate studies."
"7004920873;","Human impact on the atmospheric sulfur balance",1999,"10.1034/j.1600-0889.1999.00009.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0343402281&doi=10.1034%2fj.1600-0889.1999.00009.x&partnerID=40&md5=a2f1be953abab57f9ad0c0dee83f3ea4","The paper reviews the development in our understanding of the atmospheric part of the global sulfur cycle, including the role played by C.-G. Rossby and his colleagues in the 1950s, and presents a brief assessment of the current knowledge. Measurements of the concentrations of sulfur compounds in air, precipitation, ice cores and sea water during the past 25 years, together with recent development in three-dimensional tracer transport modeling, have resulted in a reasonably consistent picture of the burdens and fluxes of the main sulfur compounds in the atmosphere. It is clear that man's activities, in particular the burning of fossil fuels, are having a large impact on the atmospheric sulfur balance. Even on a global scale, the man-made emissions of gaseous sulfur compounds are likely to be two to three times as large as the natural sources. In and around the most heavily industrialized regions this ratio exceeds ten over extended areas. Nevertheless, there are several important issues that need to be resolved. Some of these are directly linked to the urgent problem of reducing the uncertainty in the estimate of direct and, in particular, indirect climate forcing due to man-made sulfate aerosols. One such issue is the magnitude of the wet scavenging of SO2 and aerosol sulfate during upward transport into and within the free troposphere in connection with convective and frontal cloud systems which has a decisive influence on the sulfate concentrations in the upper troposphere. Another uncertain process is the rate of oxidation of SO2 in cloud droplets and on aerosol particles. A fundamental question that remains to be answered is to what degree man-made sulfur emissions have increased the number of aerosol particles that can act as cloud condensation nuclei. Copyright © Munksgaard, 1999 all rights reserved."
"7004920873;","Human impact on the atmospheric sulfur balance",1999,"10.1034/j.1600-0870.1999.t01-1-00009.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032971480&doi=10.1034%2fj.1600-0870.1999.t01-1-00009.x&partnerID=40&md5=0b44e6bc6442184b781369a56bd0e02c","The paper reviews the development in our understanding of the atmospheric part of the global sulfur cycle, including the role played by C.-G. Rossby and his colleagues in the 1950s, and presents a brief assessment of the current knowledge. Measurements of the concentrations of sulfur compounds in air, precipitation, ice cores and sea water during the past 25 years, together with recent development in three-dimensional tracer transport modeling, have resulted in a reasonably consistent picture of the burdens and fluxes of the main sulfur compounds in the atmosphere. It is clear that man's activities, in particular the burning of fossil fuels, are having a large impact on the atmospheric sulfur balance. Even on a global scale, the man-made emissions of gaseous sulfur compounds are likely to be two to three times as large as the natural sources. In and around the most heavily industrialized regions this ratio exceeds ten over extended areas. Nevertheless, there are several important issues that need to be resolved. Some of these are directly linked to the urgent problem of reducing the uncertainty in the estimate of direct and, in particular, indirect climate forcing due to man-made sulfate aerosols. One such issue is the magnitude of the wet scavenging of SO2 and aerosol sulfate during upward transport into and within the free troposphere in connection with convective and frontal cloud systems which has a decisive influence on the sulfate concentrations in the upper troposphere. Another uncertain process is the rate of oxidation of SO2 in cloud droplets and on aerosol particles. A fundamental question that remains to be answered is to what degree man-made sulfur emissions have increased the number of aerosol particles that can act as cloud condensation nuclei."
"7402311786;7004334189;","Late-Quaternary history of the alpine flora of the New Hampshire White Mountains",1999,"10.7202/004854ar","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032696057&doi=10.7202%2f004854ar&partnerID=40&md5=c016a1e1bfd907fd9d65b3582d2e9409","A distinctive flora of 73 species of vascular plants and numerous bryophytes occurs in the ca. 20 km2 of alpine tundra in the White Mountains, New Hampshire. The late-Quarternary distribution of these plants, many of which are disjuncts, was investigated by studies of pollen and plant macrofossils from lower Lakes of the Clouds (1542 m) in the alpine zone of Mount Washington. Results were compared with pollen and macrofossils from lowland late-glacial deposits in western New England. Lowland paleofloras contained fossils of 43 species of vascular plants, 13 of which occur in the contemporary alpine flora of the White Mountains. A majority of species in the paleoflora has geographic affinities to Labrador, northern Quebec, and Greenland, a pattern also apparent for mosses in the lowland deposits. The first macrofossils in lower Lakes of the Clouds were arctic-alpine mosses of acid soils. Although open-ground mosses and vascular plants continued to occur throughout the Holocene, indicating that alpine tundra persisted, fossils of a low-elevation moss Hylocomiastrum umbratum are evidence that forest (perhaps as krummholz) covered a greater area near the basin from 7500 to 3500 yBP. No calcicolous plants were recovered from sediments at lower Lakes of the Clouds. Climatic constraints on the alpine flora during the Younger Dryas oscillation and perhaps during other cold-climate events and intervening periods of higher temperature may have led to the loss of plant species in the White Mountain alpine zone. Late-glacial floras of lowland western New England were much richer than floras of areas above treeline during late-glacial time and at the present."
"7003905014;6504687250;","Preliminary evidence of environmental changes at Lake Bambili (Cameroon, West Africa) since 24,000 BP",1999,"10.1023/A:1008098211671","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032699780&doi=10.1023%2fA%3a1008098211671&partnerID=40&md5=5824c33ec52bd9bc6443336bff90575a","Preliminary analyses of diatoms, phytoliths, and siliceous protozoan plate records in a 16 m sediment core from Lake Bambili (cameroon, West Africa; 2264 m AMSL) provide evidence of pronounced climatic changes in the West Cameroon Highlands since ~24,000 14C yrs BP. Percentages of planktonic diatoms rose with increased precipitation:evaporation ratios around 24,000 BP, ~15,000-9500 BP, and ~2400-2000 BP. Since 15,000 BP, Bambili appears to have experienced climatic changes of comparable tinting and magnitude, but with signs in opposition to those registered in the West African lowlands. Much of this pattern may be attributable to variability in montane stratiform cloud formation; which in turn is related to paleo-wind regimes and upwelling dynamics in the Gulf of Guinea."
"7401513228;","A dynamical stabilizer in the climate system: A mechanism suggested by a simple model",1999,"10.3402/tellusa.v51i3.13458","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032883258&doi=10.3402%2ftellusa.v51i3.13458&partnerID=40&md5=705ae4d7e1cf0e74fe0e025d37e4ac31","A simple zonally averaged hemispheric model of the climate system is constructed, based on energy equations for two ocean basins separated at 30°latitude with the surface fluxes calculated explicitly. A combination of empirical input and theoretical calculation is used to determine an annual mean equilibrium climate for the model and to study its stability with respect to small perturbations. The insolation, the mean albedos and the equilibrium temperatures for the two model zones are prescribed from observation. The principal agent of interaction between the zones is the vertically integrated poleward transport of atmospheric angular momentum across their common boundary. This is parameterized using an empirical formula derived from a multiyear atmospheric data set. The surface winds are derived from the angular momentum transport assuming the atmosphere to be in a state of dynamic balance on the climatic timescales of interest. A further assumption that the air-sea temperature difference and low level relative humidity remain fixed at their mean observed values then allows the surface fluxes of latent and sensible heat to be calculated. Results from a radiative model, which show a positive lower tropospheric water vapour/infrared radiative feedback on SST perturbations in both zones, are used to calculate the net upward infrared radiative fluxes at the surface. In the model's equilibrium climate, the principal processes balancing the solar radiation absorbed at the surface are evaporation in the tropical zone and net infrared radiation in the extratropical zone. The stability of small perturbations about the equilibrium is studied using a linearized form of the ocean energy equations. Ice-albedo and cloud feedbacks are omitted and attention is focussed on the competing effects of the water vapour/infrared radiative feedback and the turbulent surface flux and oceanic heat transport feedbacks associated with the angular momentum cycle. The perturbation equations involve inter-zone coupling and have coefficients dependent on the values of the equilibrium fluxes and the sensitivity of the angular momentum transport. Analytical solutions for the perturbations are obtained. These provide criteria for the stability of the equilibrium climate. If the evaporative feedback on SST perturbations is omitted, the equilibrium climate is unstable due to the influence of the water vapour/infrared radiative feedback, which dominates over the effects of the sensible heat and ocean heat transport feedbacks. The inclusion of evaporation gives a negative feedback which is of sufficient strength to stabilize the system. The stabilizing mechanism involves wind and humidity factors in the evaporative fluxes that are of comparable magnitude. Both factors involve the angular momentum transport. In including angular momentum and calculating the surface fluxes explicitly, the model presented here differs from the many simple climate models based on the Budyko-Sellers formulation. In that formulation, an atmospheric energy balance equation is used to eliminate surface fluxes in favour of top-of-the-atmosphere radiative fluxes and meridional atmospheric energy transports. In the resulting models, infrared radiation appears as a stabilizing influence on SST perturbations and the dynamical stabilizing mechanism found here cannot be identified."
"6603392379;","Studying ozone climatology with a regional climate model 1. Model description and evaluation",1999,"10.1029/1999JD900805","https://www.scopus.com/inward/record.uri?eid=2-s2.0-18744435245&doi=10.1029%2f1999JD900805&partnerID=40&md5=ffd0671c0fd448cb8ff2d0e94e689c3d","On the basis of the Canadian Regional Climate Model (CRCM) a new regional oxidant model has been developed to study ozone climatology in eastern Canada. In addition to the semi-Lagrangian advection and vertical diffusion schemes already present for tracers, a chemical module, dry deposition parameterization, and anthropogenic and on-line biogenic emissions were added to the CRCM. The complete model forms a single system which integrates meteorological and chemical variables simultaneously. Transport of 25 chemical species is evaluated on a 80 × 80 horizontal grid at 42.3 km resolution and for the 24 unequally spaced levels. The chemical scheme includes 47 species and 114 reactions used in the Acid Deposition and Oxidant Model (ADOM) gas-phase mechanism. Precalculated photolysis rates, corrected for the model cloud cover through the variations of the simulated solar radiation penetration, are used in the model. This limited-area model is driven at its boundaries by objective reanalyses for the meteorological fields and by climatological concentrations for the chemical counterparts. A time step of 15 min common to all processes is currently used. A two-step validation procedure, which includes specific cases and climatological simulations, was adopted. The first test consists of a week-long simulation for the first week of August 1988 when an intense ozone episode affected most of northeastern America during the first Eulerian Model Evaluation and Field Study (EMEFS) campaign. Results show that the CRCM ability to simulate this episode is comparable to other existing models using off-line approaches. The CRCM performance was substantially improved by the addition of the biogenic emission parameterization. Climatology-specific results are presented in the companion paper by Bouchet et al. [this issue]. Copyright 1999 by the American Geophysical Union."
"7004157687;7401584839;","Numerical simulations of convective equilibrium under prescribed forcing",1999,"10.1256/smsqj.55920","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033402216&doi=10.1256%2fsmsqj.55920&partnerID=40&md5=a9fe045e8e6c537e61b7ddc01a06b089","Some characteristic properties of simulated moist convective equilibria are examined for different imposed cooling rates. These numerical simulations extend the work of Vallis et al. and were motivated by the need to show that their conclusions (concerning the upscale energy cascade) were not sensitive to vertical resolution. Although kinetic energy does cascade to large scales, much of the large-scale motion in the model is associated with horizontally-divergent winds, and the energy spectra may be better explained as a direct consequence of the generation of convective lines. These lines have a typical spacing of about 60 km which leads to a local maximum in the kinetic-energy spectrum. In addition, the design of our experiments was found to match that envisaged in recent idealized 'heat-engine theories' of radiative-convective equilibria, thereby providing an opportunity to evaluate their utility. It is shown that a variant of these scaling theories appears to fit the statistical properties of our simulations quite well and provides expressions for the convective available potential energy, cloud mass flux and the fractional area occupied by convective updraughts. Scaling arguments also suggest that the convective line separation is of the order of the convecting layer depth divided by the square root of the updraught fractional area-consistent with the wavelength of the local maximum in the energy spectrum."
"7007088807;","Simple model to generate daily averaged point cloudiness data",1999,"10.1080/01425919908914350","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032232390&doi=10.1080%2f01425919908914350&partnerID=40&md5=6d5dfa1f0a2f822505cf9af786a57cd9","A new simple model to generate daily averaged point cloudiness values was proposed. The model uses as input the long-term mean value of point cloudiness. The model was tested in two Romanian locations. During the cold season there is a good agreement between the frequency distribution functions (FDF) obtained by using observed and generated data, respectively. When the warm season is considered, the concordance between the FDFs based on synthetic and observed data is slightly worse. The present model generates data whose mean and standard deviation are very close to those of the observed data. The model can be used to synthesize time series in those locations where the long-term mean value of point cloudiness is the only known information about the cloud cover amount. However, if both the long-term mean and standard deviation of point cloudiness are known, one recommends to use first or second order autoregressive (AR) models. If one looks about FDFs based on generated data the present model should be preferred to the usual first and second order AR models.A new simple model to generate daily averaged point cloudiness values was proposed. The model uses as input the long-term mean value of point cloudiness. The model was tested in two Romanian locations. During the cold season there is a good agreement between the frequency distribution functions (FDF) obtained by using observed and generated data, respectively. When the warm season is considered, the concordance between the FDFs based on synthetic and observed data is slightly worse. The present model generates data whose mean and standard deviation are very close to those of the observed data. The model can be used to synthesize time series in those locations where the long-term mean value of point cloudiness is the only known information about the cloud cover amount. However, if both the long-term mean and standard deviation of point cloudiness are known, one recommends to use first or second order autoregressive (AR) models. If one looks about FDFs based on generated data the present model should be preferred to the usual first and second order AR models."
"6603568514;7004539828;7102577095;","Direct climate forcing by biomass-burning aerosols: Impact of correlations between controlling variables",1999,"10.1029/1999JD900001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033609250&doi=10.1029%2f1999JD900001&partnerID=40&md5=88a6b9336137fc3453eff8fc4e2103fa","Estimates of the direct climate forcing by condensed organic species resulting from biomass burning have been made using bulk radiative transfer models of various complexity and the SUNRAY radiation code of the European Centre for Medium-Range Weather Forecasts general circulation model. Aerosols arising from the burning of tropical forests and savannas as well as those from biomass fires outside the tropics are considered. The bulk models give values ranging from -1.0 to -0.6 W m-2, which compare with -0.7 W m-2 using the SUNRAY code. There appears to be significant uncertainty in these values due to uncertainties in the model input parameters. The difference is only 13% between the forcing obtained by taking into account the spatial and temporal distribution of the controlling variables and the forcing obtained using global averages for all the variables. This indicates that the effects of variations in the controlling variables tend to compensate. Yet the forcing varies by up to 34% depending on which variables are set to global averages. The SUNRAY results show that the efficiency at which the biomass-burning aerosols backscatter sunlight in cloudy conditions is 0.53, a value significantly higher than that reported for sulfate aerosols. Most of the difference is due to the relatively low latitude (hence low sun zenith angle) of the biomass-burning aerosol sources relative to the sulfate aerosol sources. The implication is that clouds should not be assumed to have a reflectivity of unity in bulk models. Comparison of SUNRAY and bulk model results points to other potential problems with bulk models. First, the use in bulk models of mean aerosol optical properties across the entire solar spectrum has significant impact on the calculated forcing and may account for 23% of the difference between SUNRAY and bulk model estimates in clear-sky conditions. Second, neglecting multiple scattering in bulk models introduces significant differences in the clear-sky forcing at high sun zenith angles. Copyright 1999 by the American Geophysical Union."
"6602098362;7102389805;","Warm pool SST variability in relation to the surface energy balance",1999,"10.1175/1520-0442(1999)012<1292:WPSVIR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032875151&doi=10.1175%2f1520-0442%281999%29012%3c1292%3aWPSVIR%3e2.0.CO%3b2&partnerID=40&md5=0875f49f39b8d6cf73069d523a4788fc","The warm tropical oceans underlie the most convective regions on earth and are a critical component of the earth's climate, yet there are differing opinions on the processes that control warm pool SST. The Indo - Pacific warm pool is characterized by large-scale variations in SST approaching 30°C on intraseasonal timescales. In this study, surface heat flux anomalies associated with composite warm episodes over three spatial scales in both the Pacific and Indian Ocean basins are examined. The current study benefits from the recently available National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis dataset that enables the examination of variability in surface evaporation with moderate confidence. Solar flux estimates from the reanalysis are somewhat less reliable than evaporation estimates, however, and two techniques that infer surface shortwave radiation from satellite retrievals of cloud properties are considered. Error in all measurements is quantified. Both shortwave and evaporative flux variability play significant roles in modifying the temperature of the warm pool, though the relative importance of individual flux anomalies depends on SST tendency and geographical location. There also exist differences in the relative heating roles of the flux anomalies among episodes within a fixed location, though in instances the resolved differences are less than likely flux estimation error. Differences also exist between the ocean basins. A more pronounced annual cycle exists in the eastern Indian Ocean, and SST there is less sensitive to surface thermal forcing. Finally, the analysis offers evidence that SST is not regulated by a simple atmospheric thermodynamic response to the surface. Instead, the relationship between warm pool variability and large-scale dynamical features of the Tropics (e.g., intraseasonal oscillation and the seasonal monsoon) is demonstrated. The conclusions are shown to be robust to spatial scale and are consistent with a recent analysis of Tropical Oceans and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment observations."
"7003630824;57202413846;","The Global Energy Balance Archive",1999,"10.1175/1520-0477(1999)080<0831:TGEBA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001409407&doi=10.1175%2f1520-0477%281999%29080%3c0831%3aTGEBA%3e2.0.CO%3b2&partnerID=40&md5=7be44d0ccde981af2796af8758f89c32","The energy fluxes at the earth's surface determine, to a great extent, the thermal conditions and the circulation of the atmosphere. Accurate energy flux measurements, therefore, are essential for understanding (i) the formation of the present climate and (ii) the climatic changes of the past and the future. The Global Energy Balance Archive (GEBA) database currently stores 220 000 energy flux monthly means that have been measured at 1500 stations at the earth's surface. The station histories (i.e., records of known changes in instrumentation, data evaluation procedures, and data publication standards) are also stored in the GEBA database. Quality control procedures are applied to the energy flux data and energy flux data suspected of being afflicted with error are flagged. The GEBA database enables the efficient production of datasets for use in climate research. GEBA datasets have been successfully used for the reevaluation of the energy balance at the earth's surface, validation of remote sensing algorithms, validation of surface energy fluxes simulated by general circulation models, investigation of the absorption of solar radiation by clouds, and evaluation of the impact of aerosols stemming from biomass burning in equatorial regions. The GEBA database has been redesigned since 1994. This redesign included removal of contradictions in the station history data, updating of the global radiation data, and enhancement of the quality control of global radiation data. The GEBA data were made available on the Internet in October 1997."
"24423610300;8636990400;7406228987;6603239832;","Evaluation of the earth radiation budget in NCEP-NCAR reanalysis with ERBE",1999,"10.1175/1520-0442(1999)012<0477:EOTERB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033080379&doi=10.1175%2f1520-0442%281999%29012%3c0477%3aEOTERB%3e2.0.CO%3b2&partnerID=40&md5=4ff39ce786552f2d3ef0fd8b21c5bb0d","An evaluation of the NCEP-NCAR reanalysis is performed by comparing its components of the earth radiation budget to satellite data. Monthly mean clear sky (CS) and total sky of outgoing longwave radiation (OLR), and reflected solar radiation (RSW) for 1985 and 1986 are compared to the top-of-the-atmosphere (TOA) measurements from the Earth Radiation Budget Experiment (ERBE). Global RSW comparisons show that the CS data from the reanalysis is in very good agreement with ERBE, while the total-sky RSW data overestimate ERBE by 12.6 W m-2 (approximately 10%) globally. Persistent overestimate of RSW throughout the period indicates that the global energy budget for the reanalysis is not balanced.This study presents an evaluation of the NCEP-NCAR Reanalysis (the reanalysis) by comparing its components of the earth radiation budget to satellite data. Monthly mean clear sky (CS) and total sky of outgoing longwave radiation (OLR), as well as reflected solar radiation (RSW) for 1985 and 1986, are compared to the top-of-the-atmosphere atmosphere (TOA) measurements from the Earth Radiation Budget Experiment (ERBE). The ERBE-derived data of Staylor and Wilbur are also utilized to validate surface albedo. There are two objectives to this study: (i) to document the general quality of the reanalysis radiation budget, and (ii) to identify some of the general problem areas in the reanalysis global data assimilation system (GDAS). The OLR comparisons show that the global annual mean from the reanalysis is approximately 1.5% higher than that of ERBE. The zonal-average differences are strongly seasonal, which is particularly evident at high latitudes for the CS OLR, and at most latitudes for total-sky OLR. For the geographical distribution, the synoptic patterns from the reanalysis are in good agreement with the observations. Yet many regions in the Tropics and subtropics pose significant systematic biases. Possible causes are from shortcomings in the the cloud/moisture parameterizations of the reanalysis GDAS. The complex topography unresolvable by the T62 model cloud also be the cause for the biases in tall mountain regions. The global RSW comparisons show that the CS data from the reanalysis is in very good agreement with ERBE, while the total-sky RSW data overestimate ERBE by 12.6 W m-2 (~10%) globally. Persistent overestimates of RSW throughout the period indicate that the global energy budget for the reanalysis is not balanced. This result also is consistent with the finding in OLR suggesting that the reanalysis GDAS contains shortcomings in the cloud/moisture parameterizations. Another possibility for the difference in RSW is deficiencies in the GDAS shortwave parameterizations. Over the Sahara Desert, the reanalysis underestimates RSW, and overestimates OLR, both in the clear-sky and total-sky conditions. Comparison with the Staylor and Wilber ERBE-derived surface albedo suggests that GDAS surface albedo in this region should be increased by up to 0.1 (in albedo units). A comparison with the interannual variations of the satellite data for the boreal summer illustrates that the radiation budget data of the reanalysis contains a realistic climate signal."
"7003620878;13310165300;6507519092;55464967500;6603566495;7004544854;6603577295;7005391835;","Optimal measurement of surface shortwave irradiance using current instrumentation",1999,"10.1175/1520-0426(1999)016<0055:OMOSSI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032739832&doi=10.1175%2f1520-0426%281999%29016%3c0055%3aOMOSSI%3e2.0.CO%3b2&partnerID=40&md5=6eb692de2bb5d92a8b56d39378bfab81","Although most measurements of total downwelling shortwave irradiance are made with pyranometers, the World Climate Research Program's Baseline Surface Radiation Network has recommended the use of the summation of shortwave components in which the direct normal irradiance is measured and multiplied by the cosine of the solar zenith angle and then added to the diffuse horizontal irradiance measured by a pyranometer that is shaded from direct solar radiation by a disk. The nonideal angular response of most pyranometers limits their accuracy to about 3%, or 20-30 W m-2, for instantaneous clear-sky measurements. An intensive study of 21 separate measurements of total horizontal irradiance was conducted during extreme winter conditions of low sun and cold temperatures over 12 days at the National Oceanic and Atmospheric Administration's Climate Monitoring and Diagnostics Laboratory. The experiment showed that the component sum methodology could lower the uncertainty by a factor of 2 or 3. A clear demonstration of this improvement was realized in a separate experiment conducted at the Atmospheric Radiation Measurement Southern Great Plains Cloud and Radiation Testbed site during April 1996. Four independent measurements of downwelling shortwave irradiance using the component sum technique showed typical differences at solar noon of about 10 W m-2. The mean of these summed measurements at solar noon was lower than the mean of the most-well-calibrated pyranometer measurements, acquired simultaneously, by about 30 W m-2, which is consistent with the typical angular response of many pyranometers."
"57205245180;7401481611;7006366653;","The urban heat island effect at Fairbanks, Alaska",1999,"10.1007/s007040050109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033389608&doi=10.1007%2fs007040050109&partnerID=40&md5=08ef7b5a0e5243d5f6b870a8a6122512","Using climatic data from Fairbanks and rurally situated Eielson Air Force Base in Interior Alaska, the growth of the Fairbanks heat island was studied for the time period 1949-1997. The climate records were examined to distinguish between a general warming trend and the changes due to an increasing heat island effect. Over the 49-year period, the population of Fairbanks grew by more than 500%, while the population of Eielson remained relatively constant. The mean annual heat island observed at the Fairbanks International Airport grew by 0.4 °C, with the winter months experiencing a more significant increase of 1.0 °C. Primary focus was directed toward long-term heat island characterization based on season, wind speed, cloud cover, and time of day. In all cases, the minima temperatures were affected more than maxima and periods of calm or low wind speeds, clear winter sky conditions, and nighttime exhibited the largest heat island effects."
"6603808469;7402543833;","Derivation of cloud index from geostationary satellites and application to the production of solar irradiance and daylight illuminance data",1999,"10.1007/s007040050116","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033399730&doi=10.1007%2fs007040050116&partnerID=40&md5=33c580677a8061c336e27be39012debd","We investigate in the present paper the relationship between satellite count, global irradiance and other solar and illumination resource components, bringing a particular attention to low solar elevation situations (below 20°) which are very important in northern latitudes. Our investigation is based on data from two geostationary satellites, METEOSAT and GOES, backed by ground measurements in Switzerland and the northeastern USA. The study of different clear sky normalizations lead to the conclusion that a linear correlation between the global clearness index and the irradiance (like the heliosat method) would be inaccurate for low solar elevations, and therefore for high latitude regions. We developed a model that directly relates an elevation dependent clearness index to the could index. This methodology presents a definite advantage because it can be generalized to address the clearness index of other solar radiation components, besides global irradiance, such as direct irradiance, diffuse illuminance, etc. The correlations described in this paper were developed on the data from Geneva (in the frame of the EC program 'Satellight') and evaluated on two other independent data sets (Albany, USA and Lausanne, Switzerland). Their precisions, on a hourly basis, are respectively 30%, 40% and 60% for the global, diffuse and beam components) (90, 55 and 95 W/m2). The use of independent data for the derivation and the validation of the models shows that those can be used in a wide range of locations, even if the applicability has to be assessed for very different climates."
"7202583200;","Generation of the African easterly jet and its role in determining West African precipitation",1999,"10.1175/1520-0442(1999)012<1165:GOTAEJ>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032835032&doi=10.1175%2f1520-0442%281999%29012%3c1165%3aGOTAEJ%3e2.0.CO%3b2&partnerID=40&md5=d4f5b370303e026858ae9ae038d4a886","An examination of analyses and model simulations is used to show that the African easterly jet forms over West Africa in summer as a result of strong meridional soil moisture gradients. In a series of GCM experiments, the imposition of realistic surface wetness contrasts between the Sahara and equatorial Africa leads to strong positive meridional temperature gradients at the surface and in the lower troposphere; the associated easterly shear in the atmosphere is strong enough to establish easterly flow - the African easterly jet - above the monsoon westerlies at the surface. Positive temperature gradients associated with the summertime distributions of solar radiation, SSTs, or clouds are not large enough to produce the easterly jet in the absence of soil moisture gradients. A thermally direct ageostrophic circulation is identified that can accelerate the largely geostrophic zonal flow and maintain the jet. While moisture converges throughout the lower troposphere over East Africa, moisture divergence between 600 and 800 mb overlies low-level convergence over West Africa to the south of the African easterly jet. This moisture divergence is important for determining the total column moisture convergence. Since the moisture divergence is closely tied to the jet dynamics, and the jet's magnitude and position are sensitive to SST and land surface conditions, a mechanism by which the West African precipitation field is sensitive to surface conditions is suggested."
"35468686100;35464731600;55947099700;7404243086;","Remote Sensing of Tropospheric Aerosols from Space: Past, Present, and Future",1999,"10.1175/1520-0477(1999)080<2229:RSOTAF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000847315&doi=10.1175%2f1520-0477%281999%29080%3c2229%3aRSOTAF%3e2.0.CO%3b2&partnerID=40&md5=8b1fa93b71815f9d8c740e5abee6422a","Tropospheric aerosol particles originate from man-made sources such as urban/industrial activities, biomass burning associated with land use processes, wind-blown dust, and natural sources. Their interaction with sunlight and their effect on cloud microphysics form a major uncertainty in predicting climate change. Furthermore, the lifetime of only a few days causes high spatial variability in aerosol optical and radiative properties that requires global observations from space. Remote sensing of tropospheric aerosol properties from space is reviewed both for present and planned national and international satellite sensors. Techniques that are being used to enhance our ability to characterize the global distribution of aerosol properties include well-calibrated multispectral radiomelers, multispectral polarimeters, and multiangle spectroradiometers. Though most of these sensor systems rely primarily on visible to near-infrared spectral channels, the availability of thermal channels to aid in cloud screening is an important additional piece of information that is not always incorporated into the sensor design. In this paper, the various satellite sensor systems being developed by Europe, Japan, and the United States are described, and the advantages and disadvantages of each of these systems for aerosol applications are highlighted. An important underlying theme is that the remote sensing of aerosol properties, especially aerosol size distribution and single scattering albedo, is exceedingly difficult. As a consequence, no one sensor system is capable of providing totally unambiguous information, and hence a careful intercomparison of derived products from different sensors, together with a comprehensive network of ground-based sunphotometer and sky radiometer systems, is required to advance our quantitative understanding of global aerosol characteristics."
"23489942000;6603485324;7005068720;23488766200;6701464642;","Evaluation of the response of a spruce forest ecosystem on climatic changes: Results of modelling experiments",1999,"10.1016/S1464-1909(98)00019-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032830194&doi=10.1016%2fS1464-1909%2898%2900019-7&partnerID=40&md5=921d0a346cf46e91f051bc13cc8a89bb","The physical and chemical environment of forests will change in the future. How forests will react to new conditions is not known yet. In order to get an idea of the sensitivity of present forests to possible atmospheric changes, it is helpful to investigate the physiological response of forest ecosystem to a change of key environmental parameters. In order to estimate the response of a mountain spruce forest to different atmospheric conditions during the summer a six-layer non-steady-state SVAT model (SLODSVAT) was used. Eight scenarios were used for modelling energy and mass exchange during an eleven day summer period, combining different combinations of microclimatic conditions. All atmospheric scenarios were examined for three various CO2 mixing ratio levels: 350ppm (current condition), 450ppm and 550ppm. A scenario '0' assuming the current climatic features at different CO2 contents was considered as well. Structural and physiological adaptation of the forest to the new atmospheric conditions were not taken into account. For all scenarios the modelling results show increased net CO2 flux into the forest with increasing ambient CO2 concentration. Maximum net CO2 uptake was simulated for dry climate scenarios. Transpiration and evapotranspiration rates had similar trends independently of the ambient CO2 concentration used: at cold and wet conditions they decreased, while at warm and dry conditions transpiration and evapotranspiration rates increased. The influence of CO2 concentrations on transpiration rates is of minor importance if compared to changes of temperature, water vapour pressure, cloud amount and atmospheric precipitation as considered in this investigation."
"7005265040;6603501454;6602419636;","The ESA Medium Resolution Imaging Spectrometer MERIS a review of the instrument and its mission",1999,"10.1080/014311699212416","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345410964&doi=10.1080%2f014311699212416&partnerID=40&md5=57c1ff77f20259f812da552dea5dc9db","Following the successful operations of the ERS-1 and 2 satellites which are mainly dedicated to physical oceanography and ice observations from space, the European Space Agency (ESA) developed a multidisciplinary Earth observation instrument within its polar Earth Observation Programme with a focus on biological ocean observations. The Medium Resolution Imaging Spectrometer (MERIS) will be launched onboard Envisat-1 in the 1999-2000 time frame, providing a European remote sensing capability for observing for example oceanic biology and marine water quality through observations of water colour. MERIS will have a medium spectral and high radiometric resolution and a dual spatial resolution, within a global mission, covering open ocean and coastal zone waters, important aspects of the atmosphere, and large ecosystems over land. The global mission of MERIS will have a major contribution to scientific projects aimed at greater understanding of the role of oceans and ocean productivity in the climate system and our ability to forecast change through models. Secondary objectives of the MERIS mission will be directed to the measurement of atmospheric parameters associated with clouds, water vapour and aerosols in addition to land surface parameters, important in particular for the understanding of vegetation processes. In advance of the launch of MERIS, algorithms are being developed for the interpretation of MERIS observations and dedicated studies are ongoing to establish the means of validating the data products. The aim of this paper is to provide a comprehensive overview of the MERIS concept, its mission and data products in context of the driving scientific requirements. © 1999 Taylor & Francis Group, LLC."
"57214110852;7403743933;","Computing surface fluxes from Mesonet data",1999,"10.1175/1520-0450(1999)038<1370:CSFFMD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033380575&doi=10.1175%2f1520-0450%281999%29038%3c1370%3aCSFFMD%3e2.0.CO%3b2&partnerID=40&md5=88078e7be1d5aefd4321c0db7157d279","By using air-vegetation-soil layer coupled model equations as weak constraints, a variational method is developed to compute sensible and latent heat fluxes from conventional observations obtained at meteorological surface stations. This method also retrieves the top soil layer water content (daytime only) and the surface skin temperature as by-products. The method is applied to Oklahoma Mesonet data collected in the summer of 1995. Fluxes computed for selected Mesonet stations are verified against those obtained by the surface energy and radiation balance system at Atmospheric Radiation Measurement (ARM) Cloud and Radiation Testbed (CART) sites closest to the selected Mesonet stations. The retrieved values of soil water content are also compared with the direct measurements at the closest ARM CART stations. With data provided by the dense Mesonet, the method is shown to be useful in deriving the mesoscale distributions and temporal variabilities of surface fluxes, soil water content, and skin temperature. The method is unique in that it provides an additional means to derive flux fields directly from conventional surface observations."
"7006263720;","A high resolution AMIP integration using the Hadley Centre model HadAM2b",1999,"10.1007/s003820050265","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033046341&doi=10.1007%2fs003820050265&partnerID=40&md5=98273fe004d2b37c45c9b9cbc1784396","A high resolution (0.833°latitude by 1.25°longitude) AMIP (Atmospheric Model Intercomparison Project) integration is compared with a control integration at standard resolution (2.5°by 3.75°). Both integrations use HadAM2b, a recent version of the Hadley Centre atmospheric general circulation model. ECMWF reanalysis data for the AMIP period (1979-1988), together with other climatologies, are used to evaluate the results. An additional integration at standard resolution using the high resolution shorter time step is used to help distinguish between changes due to model resolution and those which are due to time step dependencies in the physical parametrizations. Enhanced resolution increases the vertical motion, intensifies the hydrological cycle, reduces slightly the model's cold bias in the troposphere, shifts the westerly jets poleward and tends to increase the eddy kinetic energy and variability of the model. The high resolution simulation has less mid-latitude cloud, so altering the radiation balance. There is no evidence to suggest that increasing resolution has an impact on the model's response to SST forcing."
"7405524900;7004544454;","Links between annual variations of Peruvian stratocumulus clouds and of SST in the eastern equatorial Pacific",1999,"10.1175/1520-0442(1999)012<3305:LBAVOP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033226461&doi=10.1175%2f1520-0442%281999%29012%3c3305%3aLBAVOP%3e2.0.CO%3b2&partnerID=40&md5=a195daa89e72c6a2961599ac94a15cce","The hypothesis that Peruvian stratocumulus play an important role on both the annual mean and annual variations of sea surface temperature (SST) in the eastern equatorial Pacific is examined. The problem is addressed by performing sensitivity experiments using the University of California, Los Angeles, coupled atmosphere-ocean GCM with different idealized temporal variations of stratocumulus in a region along the coast of Peru. The results obtained are consistent with the notion that Peruvian stratocumulus are a key component of the interhemispherically asymmetric features that characterize the annual mean climate of the eastern equatorial Pacific, including the cold SSTs off Peru and the absence of a southern ITCZ. The principal new finding of this study is that the annual variations (i.e., deviations from the annual mean) of Peruvian stratocumulus are linked to the differences between the amplitude, duration, and westward propagation of the warm and cold phases of the equatorial cold tongue. In the model's context, only if the prescribed annual variations of Peruvian stratocumulus have the same phase as the observed variations are those differences successfully captured. The impact of Peruvian stratocumulus on equatorial SST involves 'dynamical' and 'thermal' effects. The former develop through an enhancement of the northerly component of the surface wind from the Peruvian coast to the equator. The thermal effects develop through the special relationships between SST and surface evaporation over the equatorial cold tongue, which contributes to extend the cold phase until the end of the year. A successful portrayal of this behavior requires a realistic simulation of the annual variations of surface wind over the equatorial cold tongue."
"56917398600;6602674288;","Results of year-round remotely sensed integrated water vapor by ground-based microwave radiometry",1999,"10.1175/1520-0450(1999)038<0981:ROYRRS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032712310&doi=10.1175%2f1520-0450%281999%29038%3c0981%3aROYRRS%3e2.0.CO%3b2&partnerID=40&md5=87ef2245a5463eaea2566da68ac8a18a","Based on two years of measurements with a time resolution of 1 min, some climatological findings on precipitable water vapor (PWV) and cloud liquid water (CLW) in central Europe are given. A weak diurnal cycle is apparent. The mean overall diurnal variation was about 0.15 cm in summer and 0.05 cm in winter, equivalent to 8% and 5%, respectively. The PWV increase starts in summer at about 0800 local time and has a maximum of about 0.02 cm h-1 between 1000 and 1500 local time, equivalent to about 1% PWV h-1. There was, on average, no PWV variation during the night in winter. PWV decreased in winter during the morning with a maximum of 0.01 cm h-1 and increased in the afternoon with a maximum of 0.01 cm h-1. Thus, the accuracy of the monthly means of PWV based on monitoring systems with low-time resolution (satellites, radiosondes) is only slightly affected by the diurnal course of PWV in central Europe. On average an increase in PWV and CLW was found in the 30-min interval before precipitation in summer. The PWV increase was, however, only about 0.1 cm or 5% of PWV within the last 2 h before rain. The corresponding CLW increase was 0.1 mm, which is considerable as precipitation was observed when CLW reached 0.3-0.4 mm.Based on two years of measurements with a time resolution of 1 min, some climatological findings on precipitable water vapor (PWV) and cloud liquid water (CLW) in central Europe are given. A weak diurnal cycle is apparent. The mean overall diurnal variation was about 0.15 cm in summer and 0.05 cm in winter, equivalent to 8% and 5%, respectively. The PWV increase starts in summer at about 0800 local time and has a maximum of about 0.02 cm h-1 between 1000 and 1500 local time, equivalent to about 1% PWV h-1. There was, on average, no PWV variation during the night in winter. PWV decreased in winter during the morning with a maximum of 0.01 cm h-1 and increased in the afternoon with a maximum of 0.01 cm h-1. Thus, the accuracy of the monthly means of PWV based on monitoring systems with low-time resolution (satellites, radiosondes) is only slightly affected by the diurnal course of PWV in central Europe. On average an increase in PWV and CLW was found in the 30-min interval before precipitation in summer. The PWV increase was, however, only about 0.1 cm or 5% of PWV within the last 2 h before rain. The corresponding CLW increase was 0.1 mm, which is considerable as precipitation was observed when CLW reached 0.3-0.4 mm."
"57214052634;15923911200;7404441387;","Landsat MSS-derived land-cover map of northern Alaska: Extrapolation methods and a comparison with photo-interpreted and AVHRR-derived maps",1999,"10.1080/014311699211543","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033569110&doi=10.1080%2f014311699211543&partnerID=40&md5=b5a8c71084e67f3ac5cf4a41e39fff78","Vegetation maps of Arctic areas are needed for a variety of tundra ecosystem and climate change studies and for extrapolating from relatively small, well-known sites to broader regions. We made a preliminary land-cover map of northern Alaska by extrapolating a Landsat Multi-Spectral Scanner (MSS) derived classification of the Kuparuk River Region (KRR) to all of northern Alaska. We used a 26-scene mosaic that was previously made by the EROS Data Center, and a K-means unsupervised classification algorithm to produce eight broad land-cover categories. The northern Alaska-MSS map (NA-MSS) has the following land-cover categories and respective percentage coverage within the 200000km2 Arctic Slope: Dry Prostrate-shrub Tundra and Barrens, 8%; Moist Graminoid, Prostrate-shrub Tundra, 22%; Moist Tussock-graminoid, Dwarf-shrub Tundra, 4%; Moist Dwarf-shrub, Tussock-graminoid, Tundra, 28%; Moist Lowshrub Tundra and other Shrublands, 19%; Wet Graminoid Tundra, 9%; Water, 6%; Clouds and ice, <1%; Shadows, 4%. Ancillary data were used to improve the classification for a region of sandy tundra not encountered in the KRR and to separate shadows in the mountains from water and wetlands elsewhere. The NA-MSS map helps to define the distribution of a recently described moist nonacidic (calcareous) tundra and areas of shrublands that are of broad interest to the tundra- and climate-change modelling communities. A boundary separating moist acidic tundra from moist nonacidic tundra stretches across all of northern Alaska (about 850km). Shrub-dominated tundra is prevalent in the southern and western (warmer, wetter) portions of the map. We created difference maps for comparing the northern Alaska-MSS (NA-MSS) map to the Major Ecosystems of Alaska (MEA) map and a map derived from a time series of Advanced Very High Resolution Radiometer images (NA-AVHRR). Compared to the other maps, the NA-MSS map provides more detailed information for moist tundra areas and shows more shrub-dominated vegetation with different spatial distributions than the other two maps. An accuracy assessment of the map will be performed in 1999. © 1999 Taylor and Francis Ltd."
"7005477332;7005140378;23476370700;7003907406;7404871794;7004377842;7005006917;7004208584;6602079010;","New Directions in Earth Observing: Scientific Applications of Multiangle Remote Sensing",1999,"10.1175/1520-0477(1999)080<2209:NDIEOS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000821855&doi=10.1175%2f1520-0477%281999%29080%3c2209%3aNDIEOS%3e2.0.CO%3b2&partnerID=40&md5=cd6cac5a684941c834006f7ed474e38a","The physical interpretation of simultaneous multiangle observations represents a relatively new approach to remote sensing of terrestrial geophysical and biophysical parameters. Multiangle measurements enable retrieval of physical scene characteristics, such as aerosol type, cloud morphology and height, and land cover (e.g., vegetation canopy type), providing improved albedo accuracies as well as compositional, morphological, and structural information that facilitates addressing many key climate, environmental, and ecological issues. While multiangle data from wide field-of-view scanners have traditionally been used to build up directional ""signatures"" of terrestrial scenes through multitemporal compositing, these approaches either treat the multiangle variation as a problem requiring correction or normalization or invoke statistical assumptions that may not apply to specific scenes. With the advent of a new generation of global imaging spectroradiometers capable of acquiring simultaneous visible/near-IR multiangle observations, namely, the Along-Track Scanning Radiometer-2, the Polarization and Directionality of the Earth's Reflectances instrument, and the Multiangle Imaging SpectroRadiometer, both qualitatively new approaches as well as quantitative improvements in accuracy are achievable that exploit the multiangle signals as unique and rich sources of diagnostic information. This paper discusses several applications of this technique to scientific problems in terrestrial atmospheric and surface geophysics and biophysics."
"6602253099;57209757800;","Rapid estimation of photosynthetically active radiation over the West African Sahel using the Pathfinder Land Data Set",1999,"10.1016/s0303-2434(99)85014-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646255119&doi=10.1016%2fs0303-2434%2899%2985014-4&partnerID=40&md5=af73a79bd3bce9810f06d350bf707523","Photosynthetically Active Radiation (PAR) is important for assessing both the impact of changing land cover on climate, and for modelling productivity on a regional scale, as well as its potential in areas that are vulnerable to food shortfalls. A relatively simple method that generates spatially comprehensive and representative values of PAR at time scales of 10-days (dekads) or longer is described, tested and implemented over a portion of West Africa. With simple equations to describe the geographical and temporal variation of global radiation receipt at the top of the atmosphere, daily cloud flags from the NOAA/NASA AVHRR Pathfinder Land Data Set (PAL) are used in conjunction with an empirical formula developed by Ångström and constants tailored to West African conditions to estimate surface receipt of global radiation there. Ground observations of PAR from the HAPEX Sahel experiment (at 13°66′ N and 2°53′ E from 1992) are used to parameterise the relative sunshine duration variable in the Ångström relation so as to minimise errors between observed and modelled PAR. Results indicate that PAR may be estimated to within 20 percent of observed values for 28 out of 36 10-day summation periods over a year. End-of-year accumulated PAR is estimated to within 1.96 percent. Normalised root mean square errors (NRMSEs) and normalised mean absolute errors (NMAEs) of 15.69 percent and 12.46 percent, respectively, were obtained for 10-day sums, with values of 10.96 percent and 8.74 percent, respectively, for monthly sums. The spatial variability of end-of-year PAR for 1992 is in accordance with what was expected. Though more accurate methods exist for achieving this, the technique is merited for its ease of application, using an accessible data set, over areas where solar irradiation measurements are lacking."
"7003535176;55684491100;6602896240;7102781936;7004168885;","A distribution law for relative humidity in the upper troposphere and lower stratosphere derived from three years of MOZAIC measurements",1999,"10.1007/s00585-999-1218-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345516757&doi=10.1007%2fs00585-999-1218-7&partnerID=40&md5=f48411b50bef3134df54e283ca278f97","Data from three years of MOZAIC measurements made it possible to determine a distribution law for the relative humidity in the upper troposphere and lower stratosphere. Data amounting to 13.5% of the total were obtained in regions with ice supersaturation. Troposphere and stratosphere are distinguished by an ozone concentration of 130 ppbv as threshold. The probability of measuring a certain amount of ice supersaturation in the troposphere decreases exponentially with the degree of ice supersaturation. The probability of measuring a certain relative humidity in the stratosphere (both with respect to water and ice) decreases exponentially with the relative humidity. A stochastic model that naturally leads to the exponential distribution is provided. Mean supersaturation in the troposphere is about 15%, whereas ice nucleation requires 30% supersaturation on the average. This explains the frequency of regions in which aircraft induce persistent contrails but which are otherwise free of clouds. Ice supersaturated regions are 3-4 K colder and contain more than 50% more vapour than other regions in the upper troposphere. The stratospheric air masses sampled are dry, as expected, having mean relative humidity over water of 12% and over ice of 23%, respectively. However, 2% of the stratospheric data indicate ice supersaturation. As the MOZAIC measurements have been obtained on commercial flights mainly between Europe and North America, the data do not provide a complete global picture, but the exponential character of the distribution laws found is probably valid globally. Since water vapour is the most important greenhouse gas and since it might enhance the anthropogenic greenhouse effects via positive feedback mechanisms, it is important to represent its distribution correctly in climate models. The discovery of the distribution law of the relative humidity makes possible simple tests to show whether the hydrological cycle in climate models is represented in an adequate way or not."
"6701653010;7101685611;7406215388;7005490049;7004884101;","Tropical rainfall associated with convective and stratiform clouds: Intercomparison of disdrometer and profiler measurements",1999,"10.1175/1520-0450(1999)038<0302:TRAWCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032718255&doi=10.1175%2f1520-0450%281999%29038%3c0302%3aTRAWCA%3e2.0.CO%3b2&partnerID=40&md5=9c5e36a1ab5f17adb2e5211cf7f17ac6","The motivation for this research is to move in the direction of improved algorithms for the remote sensing of rainfall, which are crucial for meso- and large-scale circulation studies and climate applications through better determinations of precipitation type and latent heating profiles. Toward this end a comparison between two independent techniques, designed to classify precipitation type from 1) a disdrometer and 2) a 915-MHz wind profiler, is presented, based on simultaneous measurements collected at the same site during the Intensive Observing Period of the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. Disdrometer-derived quantities such as differences in drop size distribution parameters, particularly the intercept parameter N0 and rainfall rate, were used to classify rainfall as stratiform or convective. At the same time, profiler-derived quantities, namely, Doppler velocity, equivalent reflectivity, and spectral width, from Doppler spectra were used to classify precipitation type in four categories: shallow convective, deep convective, mixed convective-stratiform, and stratiform. Overall agreement between the two algorithms is found to be reasonable. Given the disdrometer stratiform classification, the mean profile of reflectivity shows a distinct bright band and associated large vertical gradient in Doppler velocity, both indicators of stratiform rain. For the disdrometer convective classification the mean profile of reflectivity lacks a bright band, while the vertical gradient in Doppler velocity below the melting level is opposite to the stratiform case. Given the profiler classifications, in the order shallow-deep-mixed-stratiform, the composite raindrop spectra for a rainfall rate of 5 mm h-1 show an increase in D0, the median volume diameter, consistent with the dominant microphysical processes responsible for drop formation. Nevertheless, the intercomparison does reveal some limitations in the classification methodology utilizing the disdrometer or profiler algorithms in isolation. In particular, 1) the disdrometer stratiform classification includes individual cases in which the vertical profiles appear convective, but these usually occur at times when the disdrometer classification is highly variable; 2) the profiler classification scheme also appears to classify precipitation too frequently as stratiform by including cases that have small vertical Doppler velocity gradients at the melting level but no bright band; and 3) the profiler classification scheme includes a category of mixed (stratiform-convective) precipitation that has some features in common with deep convection (e.g., enhanced spectral width above the melting level) but other features in common with stratiform precipitation (e.g., well-developed melting layer signature). Comparison of the profiler-derived vertical structure with disdrometer-determined rain rates reveals that almost all cases of rain rates greater than 10 mm h-1 are convective. For rain rates less than 5 mm h-1 all four profiler-determined precipitation classes are well represented."
"7003535176;7004194999;55684491100;","A diagnostic study of the global distribution of Contrails Part II: Future air traffic scenarios",1999,"10.1007/s007040050087","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032828254&doi=10.1007%2fs007040050087&partnerID=40&md5=775b9ecfbe47f503ef5c0feca65edd17","The global distribution of the contrail coverage is computed for several scenarios of aviation in the years 2015 and 2050 and compared to 1992 using meteorological analysis data representative of present temperature and humidity conditions and assuming 0.5% cover in a reference region 30°W-30°E, 35°N-75°N covering parts of western Europe and the North Atlantic. The mean contrail coverage of the Earth is computed to increase by a factor of about three compared to 1992 and to reach 0.25% in 2015. For three different scenarios of aviation and for constant climatic conditions, the global mean contrail coverage reaches values between 0.26% and 0.75% for 2050. Contrail coverage increases more strongly than total fuel burn mainly because of more traffic in the upper troposphere and because of more efficient engines with cooler exhaust. The overall efficiency of propulsion is expected to grow from about 0.3 in the fleet average of 1992, to 0.4 in 2015, and to 0.5 in 2050. The expansion of air traffic makes Canada, Alaska, the North Pacific route from North America to Japan and most of the Asian continent new regions where contrails are expected to cover more than 0.5% on average."
"6603779272;","Radiative forcing from tropospheric ozone calculated with a unified chemistry-climate model",1999,"10.1029/1999JD900439","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033590326&doi=10.1029%2f1999JD900439&partnerID=40&md5=783643e7ed602852700d6cff7a140a60","We have developed a global model for the study of chemistry-climate interactions by incorporating a detailed simulation of tropospheric ozone-NOxhydrocarbon chemistry within a general circulation model (GCM). We present a first application of the model to the calculation of radiative forcing from tropospheric ozone since preindustrial times. Longwave and shortwave radiation fluxes are computed every 5 hours in the GCM using the locally simulated ozone fields. In this manner, the model resolves synoptic-scale correlations between ozone and meteorological variables. A simulation for present-day conditions is compared to a preindustrial atmosphere (∼1800 A.D.) with no fossil fuel combustion, 10% of present-day biomass burning, and 0.7 ppm methane. The two simulations use the same meteorological fields; the radiative forcing does not feed back into the GCM. The model reproduces well the observed distributions of ozone and its precursors in the present-day atmosphere. Increases in ozone since preindustrial times are 20-200% depending on region and season. The global mean, instantaneous radiative forcing from anthropogenic ozone is 0.44 W m2 (0.35 longwave, 0.09 shortwave). The model reveals large shortwave forcings (0.3-0.7 W m2 ) over polar regions in summer. The total forcing is greater than 1.0 W m2 over large areas, including the Arctic, during Northern Hemisphere summer. The normalized radiative forcing per unit of added ozone column varies globally from -0.01 to 0.05 W m2. This variance can be explained in large part by the temperature difference between the surface and the tropopause; clouds are an additional factor, particularly at low latitudes. An off-line radiative calculation using the same ozone fields but averaged monthly shows nearly identical forcings, with differences less than ±2% over most of the Earth. The similarity between the off-line and on-line simulations suggests that the common use of off-line ozone fields is acceptable in radiative forcing calculations. Addition of the direct forcings from anthropogenic sulfate aerosol and tropospheric ozone computed with the same GCM shows compensating effects, with sulfate dominating at northern midlatitudes and ozone usually dominating elsewhere. Copyright 1999 by the American Geophysical Union."
"7103246957;8060387000;7006103811;","Controls on evaporation in a boreal spruce forest",1999,"10.1175/1520-0442(1999)012<1601:COEIAB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032745593&doi=10.1175%2f1520-0442%281999%29012%3c1601%3aCOEIAB%3e2.0.CO%3b2&partnerID=40&md5=c305c0d2d1a9ca03ee081666d650a041","The surface energy balance over a boreal spruce forest is analyzed using 3 yr of 30-min-averaged data collected during the 1994-96 Boreal Ecosystem-Atmosphere Study experiment 40 km west of Thompson, Manitoba. Through this analysis, the climatic controls on surface environment are shown. The seasonal variation of evapotranspiration is lowest in spring when the ground is frozen, highest in summer, and lower again in fall after frost.The surface energy balance over a boreal spruce forest is analyzed using 3 yr of 30-min-averaged data collected during the 1994-96 Boreal Ecosystem-Atmosphere Study experiment 40 km west of Thompson, Manitoba, to show the climatic controls on surface evapotranspiration. The seasonal variation of evaporation is shown: lowest in spring when the ground is frozen, highest in summer (although daytime evaporative fractions are only 0.4), and lower again in fall after frost. The surface sensible heat flux in contrast is high in spring, when evaporation is low. Evaporation is much higher when the surface, including the moss layer, is wet. At all temperatures (in summer), evaporative fraction falls with increasing light level, because of the high vegetative resistance of the forest system. Using a Monin-Obukhov formulation and a bulk vegetation model, the vegetative resistance for the boreal spruce forest system is calculated. This bulk vegetative resistance decreases with increasing photosynthetic radiation, decreases sharply with relative humidity, decreases with increasing surface water storage, and is lower on cloudy days than on sunny days with the same incoming photosynthetic radiation. Vegetative resistance at its midmorning minimum is lower by a factor of 4 when the moss surface is very wet. As over grassland sites, the lower surface resistance to evaporation directly influences the diurnal cycle of lifting condensation level and cloud-base height, which are much lower on days with a wet surface. The reduction of vegetative resistance under cloudy skies at the same incoming radiation level presumably reflects the more efficient use of diffuse radiation by the canopy for photosynthesis. Vegetative resistance is roughly doubled in spring, when the ground is frozen, and is higher in fall after frost. About 63% of the observed variance in vegetative resistance can be explained in terms of meteorological variables using multiple linear regression. Some measurement issues are addressed in an appendix. The residual in the energy balance falls with increasing wind speed, which may be due to a small (10%-15%) underestimation of the sensible and latent heat fluxes at low wind speeds. During spring melt, however, this residual has a high daytime value of 30% of net radiation. The residual is also much higher on sunny days than on cloudy days."
"7403288995;7102875645;","The role of water vapor feedback in unperturbed climate variability and global warming",1999,"10.1175/1520-0442(1999)012<2327:trowvf>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033172671&doi=10.1175%2f1520-0442%281999%29012%3c2327%3atrowvf%3e2.0.co%3b2&partnerID=40&md5=90c159d8a4881c1bd48aef2b75e39a69","To understand the role of water vapor feedback in unperturbed surface temperature variability, a version of the Geophysical Fluid Dynamics Laboratory coupled ocean-atmosphere model is integrated for 1000 yr in two configurations, one with water vapor feedback and one without. For all spatial scales, the model with water vapor feedback has more low-frequency (timescale ≥ 2 yr) surface temperature variability than the one without. Thus water vapor feedback is positive in the context of the model's unperturbed variability. In addition, water vapor feedback is more effective the longer the timescale of the surface temperature anomaly and the larger its spatial scale. To understand the role of water vapor feedback in global warming, two 500-yr integrations were also performed in which CO2 was doubled in both model configurations. The final surface global warming in the model with water vapor feedback is 3.38°C, while in the one without it is only 1.05°C. However, the model's water vapor feedback has a larger impact on surface warming in response to a doubling of CO2 than it does on internally generated, low-frequency, global-mean surface temperature anomalies. Water vapor feedback's strength therefore depends on the type of temperature anomaly it affects. The authors found that the degree to which a surface temperature anomaly penetrates into the troposphere is a critical factor in determining the effectiveness of its associated water vapor feedback. The more the anomaly penetrates, the stronger the feedback. It is also shown that the apparent impact of water vapor feedback is altered by other feedback mechanisms, such as albedo and cloud feedback. The sensitivity of the results to this fact is examined. Finally, the authors compare the local and global-mean surface temperature time series from both unperturbed variability experiments to the observed record. The experiment without water vapor feedback does not have enough global-scale variability to reproduce the magnitude of the variability in the observed global-mean record, whether or not one removes the warming trend observed over the past century. In contrast, the amount of variability in the experiment with water vapor feedback is comparable to that of the global-mean record, provided the observed warming trend is removed. Thus, the authors are unable to simulate the observed levels of variability without water vapor feedback."
"56627414400;","Bringing climate models into agreement with observations of atmospheric absorption",1999,"10.1175/1520-0442(1999)012<1589:BCMIAW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032695295&doi=10.1175%2f1520-0442%281999%29012%3c1589%3aBCMIAW%3e2.0.CO%3b2&partnerID=40&md5=2890d13eebb4fd1bcf4eb2371de128b6","A comparison of the output of two data assimilation models with a quasi-global, multilayer set of monthly mean observations shows that the models underestimate the amount of solar energy absorbed in the atmosphere by 15-30 W m-2, out of a total of approx. 80 W m-2. In addition, observations show a much stronger dependence of absorption on column water vapor than models. Here the author analyzes absorption measured between two aircraft on a clear day during the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE) and finds a similarly strong dependence of absorption on water vapor. This common feature, in disparate types of observations, suggests the possible existence of appreciable continuum absorption in the water vapor spectrum. Various formulations of continuum absorption are tested against the aircraft observations and against the monthly mean dataset. In both cases, the addition of continuum absorption brings the models substantially closer to the observations, especially in the dependence of absorption on column water vapor. Of the two data assimilation models considered, introducing either an e-type continuum or one based on dimers - with the overall magnitude of the absorption coefficient adjusted to obtain agreement with the aircraft measurements - the overall discrepancy with respect to the monthly mean observations is reduced from 28 to about 17 W m-2 for the Goddard Earth Observing System-1 model, and from 18 to about 7 W m-2 for the National Centers for Environmental Prediction model.A comparison of the output of two data assimilation models with a quasi-global, multiyear set of monthly mean observations shows that the models underestimate the amount of solar energy absorbed in the atmosphere by 15-30 W m-2, out of a total of ~80 W m-2. In addition, observations show a much stronger dependence of absorption on column water vapor than models. Here the author analyzes absorption measured between two aircraft on a clear day during the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE) and finds a similarly strong dependence of absorption on water vapor. This common feature, in disparate types of observations, suggests the possible existence of appreciable continuum absorption in the water vapor spectrum. Various formulations of continuum absorption are tested against the aircraft observations and against the monthly mean dataset. In both cases, the addition of continuum absorption brings the models substantially closer to the observations, especially in the dependence of absorption on column water vapor. Of the two data assimilation models considered, introducing either an e-type continuum or one based on dimers-with the overall magnitude of the absorption coefficient adjusted to obtain agreement with the aircraft measurements-the overall discrepancy with respect to the monthly mean observations is reduced from 28 to about 17 W m-2 for the Goddard Earth Observing System-1 model, and from 18 to about 7 W m-2 for the National Centers for Environmental Prediction model."
"7401844779;7101886364;56544359000;56270311300;57198879470;7004570296;7201966094;35465220500;16185051500;","Aerosol-induced radiative flux changes off the United States mid-Atlantic coast: Comparison of values calculated from sunphotometer and in situ data with those measured by airborne pyranometer",1999,"10.1029/1998JD200025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033608192&doi=10.1029%2f1998JD200025&partnerID=40&md5=f2553458b6707b17479563b2f888153f","The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) measured a variety of aerosol radiative effects (including flux changes) while simultaneously measuring the chemical, physical, and optical properties of the responsible aerosol particles. Here we use TARFOX-determined aerosol and surface properties to compute shortwave radiative flux changes for a variety of aerosol situations, with midvisible optical depths ranging from 0.06 to 0.55. We calculate flux changes by several techniques with varying degrees of sophistication, in part to investigate the sensitivity of results to computational approach. We then compare computed flux changes to those determined from aircraft measurements. Calculations using several approaches yield downward and upward flux changes that agree with measurements. The agreement demonstrates closure (i.e., consistency) among the TARFOX-derived aerosol properties, modeling techniques, and radiative flux measurements. Agreement between calculated and measured downward flux changes is best when the aerosols are modeled as moderately absorbing (midvisible single-scattering albedos between about 0.89 and 0.93), in accord with independent measurements of the TARFOX aerosol. The calculated values for instantaneous daytime upwelling flux changes are in the range +14 to +48 W m-2 for midvisible optical depths between 0.2 and 0.55. These values are about 30 to 100 times the global-average direct forcing expected for the global-average sulfate aerosol optical depth of 0.04. The reasons for the larger flux changes in TARFOX include the relatively large optical depths and the focus on cloud-free, daytime conditions over the dark ocean surface. These are the conditions that produce major aerosol radiative forcing events and contribute to any global-average climate effect. Copyright 1999 by the American Geophysical Union."
"7004426987;7005677213;57210198318;7005423082;","Comparison of landsat TM-derived and ground-based albedos of haut glacier d'Arolla, Switzerland",1999,"10.1080/014311699211345","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033589459&doi=10.1080%2f014311699211345&partnerID=40&md5=b84495f2f94e1987e4a97a6b7e5c22e2","Measurements of the surface albedo of Haut Glacier d'Arolla (Switzerland) derived from Landsat Thematic Mapper data (alphaTM) are compared with ground-based albedo measurements (alphag). The analysis is based on (a) 137 aground-based measurements made at 67 sites during three extensive glacier surveys in the 1993 ablation season, and (b) data acquired during three corresponding cloud-free Landsat overpasses on 29 May, 1 and 17 August. For the first overpass large differences in the snow albedo are found (average:alphaTM 0.73, alphag0.55), which are attributed to snowfall and metamorphism of snow between the times of the satellite overpass and the ground measurements. For the second overpass there is much better agreement between the two snow albedos (average: alphaTM 0.56, alphag 0.51). For the second and third overpass there is good agreement between alphaTM and alphag of glacier ice (average:alphaTM 0.17, alphag0.19). However, the scatter in alphaTMalpha g is large which is very probably related to the high spatial variability of the ice albedo over distances of only a few metres and the smallscale coverage (in terms of ground area) of the ground measurements compared to the TM pixel size. In addition, there is a tendency for alphaTM to overestimate low values of alphag and to underestimate high values. This is explained by a possible bias in the ground-based measurements towards selecting either relatively clean or relatively dirty ice surfaces. Several errors associated with uncertainties in the method of albedo retrieval are discussed. It is suggested that the assumption of an isotropically reflecting surface is a main source of error in the satellite-derived albedo. © 1999 Taylor and Francis Ltd."
"6507557026;7102224078;","The use of coincident DMSP SSM/I and OLS satellite data to improve snow cover detection and discrimination",1999,"10.1080/014311699213451","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033585468&doi=10.1080%2f014311699213451&partnerID=40&md5=a94051c8cfaaf2cc52bfe78fd272e1ce","The use of Special Sensor Microwave Imager (SSM/I) data for snow cover detection has been well documented since the launch of the first Defence Meteorological Satellite Program (DMSP) platform in 1987. One of the major problems yet to be resolved is the successful discrimination and subsequent removal of precipitation areas from snow cover estimates at high latitudes: this can have a significant impact on the ability to detect snow cover. Both snow cover and precipitation can exhibit similar responses at SSM/I microwave frequencies. The majority of snow cover algorithms eliminate precipitation using a single brightness temperature threshold at either 19 or 22GHz and perform adequately under most conditions. It has been observed that this threshold must be varied under given surface and atmospheric conditions by as much as 5-10 K. This can result in large errors in both snow cover and precipitation estimates when climatically aggregated, but is also evident in some individual case study events. By using additional thermal infrared (IR) data from the DMSP Operational Line Scanner (OLS) a synergistic approach has been applied. In theory a snow cover will have a much warmer OLS IR temperature than the type of precipitating clouds that give a similar response at microwave frequencies to the snow cover. The IR data can be used to identify more accurately the snow cover. The OLS has the advantage also of an improved spatial resolution over the SSM/I, and a synergistic approach will not deteriorate the spatial resolution of the SSM/I estimate. A synergistic algorithm has been developed and tested over three case study areas and demonstrates a qualitative improvement in the detection of snow cover under difficult conditions. © 1999 by Taylor and Francis Ltd."
"7202140067;6506655377;6603605128;57217272857;","Effects of weather conditions and trap types on sampling for richness and abundance of forest macrolepidoptera",1999,"10.1093/ee/28.5.795","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032741868&doi=10.1093%2fee%2f28.5.795&partnerID=40&md5=b8576acf059050fe7415a2aa7ad8a17d","In a 3-year study (1991-1993), we compared blacklight and Townes-style Malaise traps for assessing richness and abundance of forest macrolepidoptera in 4 small watersheds in the Fernow Experimental Forest in West Virginia. From early May through mid-August each year, sampling was conducted by one 8-W blacklight trap and 5 Townes-type Malaise traps in each watershed] Light traps were operated 1 night each week; Malaise traps operated continuously with the samples collected every 10 d. Over all years, macrolepidopteran species richness and abundance were 343 and 36,160 and 273 and 28,246 for light trap and Malaise trap samples, respectively. Percentage of total macrolepidopteran species per family was similar in both collecting methods although both diurnal and nocturnal lepidopterans were represented in Malaise samples. Differences were noted in percentage of total abundance by family. For example, geometrid abundance was similar in both sample types and represented the highest overall abundance, whereas the proportion of arctiids and notodontids was higher in light trap samples, and proportional abundance of noctuids was higher in Malaise trap samples. There were 135 and 65 species unique to light trap and Malaise trap samples, respectively. Abundance of macrolepidopterans sampled by both methods was highest in 1991 (a warm, dry year) and lowest in 1992 (a cool, wet year). Minimum ambient temperature and rainfall significantly affected the sizes of samples from blacklight traps, based on multiple-regression analysis. Moonlight in the absence of cloud cover reduced moth catch in blacklight traps. Mean ambient temperature, but not total rainfall, during trapping periods significantly affected the sizes of Malaise-trap samples based on a multiple autoregression analysis."
"6602737034;55860027600;","Simulation of tropical cyclone circulation over Bay of Bengal using the Arakawa-Schubert cumulus parametrization. Part I-Description of the model, initial data and results of the control experiment",1999,"10.1007/s000240050311","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0342905078&doi=10.1007%2fs000240050311&partnerID=40&md5=9ad18e97f9e16bd08a7848ed4b048045","A ten-level axi-symmetric primitive equation model with cylindrical coordinates is used to simulate the tropical cyclone evolution from a weak vortex for the Bay of Bengal region. The physics of the model comprises the parameterization schemes of Arakawa-Schubert cumulus convection (Lord et al., 1982) and Deardorff's (1972) planetary boundary layer. The initial conditions have been taken from the climate mean data for November of Port Blair (92.4 E, 11.4 N) in the Bay of Bengal, published by the India Meteorological Department. An initial vortex has been designed to have tangential wind maximum of 10 m/s at 120-km radius with a central surface pressure of 1008 hPa. As a control experiment, referred to as ASBB1, the model is integrated for 240 h maintaining the sea-surface temperature (SST) constant at 301 K. The results of the control experiment reveal a slow decrease of the Central Surface Pressure (CSP) from the initial value of 1008 hPa to 970 hPa at 156 h. After 156 h the CSP decreased sharply until 186 h, attaining 890 hPa. The tangential wind at 1 km level attained the Cyclone Threshold Intensity (CTI) of 17 m/s around 78 h and a maximum of 87 m/s was found at 210 h. These features indicate a predeveloping stage up to 156 h, a deepening stage of 30 h from 156-186 h followed by the mature stage. The mature stage is characterized by the simulation of the central eye region, warm core, strong cyclonic circulation in the central 300 km with low-level inflow; strong vertical motion at the eye wall and outflow aloft. The convection features of the different cloud types conform with the circulation features. The control experiment clearly indicates the evolution of a cyclone with hurricane intensity from a weak vortex. In part two of the paper, results from sensitivity experiments with respect to variations in latitude, SST and initial thermodynamic state have been presented."
"7404937258;7007065694;57196972176;55167977900;","Methods for snowmelt forecasting in upland Britain",1999,"10.5194/hess-3-233-1999","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032846707&doi=10.5194%2fhess-3-233-1999&partnerID=40&md5=02402f5a7ffafe0531444f4d9b353fb0","Snow, whilst not a dominant feature of Britain's maritime climate, can exert a significant influence on major floods through its contribution as snowmelt. Flood warning systems which fail to take account of melting snow can prove highly misleading. Selected results of a study on methods for improved snowmelt forecasting using trial catchments in upland Britain are presented here. Melt models considered range from a temperature excess formulation, with the option to include wind and rain heating effects, to a full energy budget melt formulation. Storage of melt in the pack is controlled by a store with two outlets, allowing slow release of water followed by rapid release once a critical liquid water content is reached. For shallow snow packs, a partial cover curve determines the proportion of the catchment over which snow extends. The melt, storage and release mechanisms together constitute the PACK snowmelt module which provides inputs to the catchment model. Either a lumped or a distributed catchment model can be used, configured to receive snowmelt inputs from elevation zones within the catchment; a PACK snowmelt module operates independently within each zone and its inputs are controlled by appropriate elevation lapse rates. Measurements of snow depth and/or water equivalent, from snow cores or a snow pillow, are assimilated to correct for a lack of direct snowfall measurements needed to maintain a water balance during snowfall. The updating scheme involves operating a PACK module at the measurement site (the 'point model') in parallel to PACK modules in the catchment model, with point model errors being transferred using a proportioning scheme to adjust the snowpack water contents of the catchment model. The results of the assessment of different model variants broadly favour the simpler model formulations. Hourly automatic monitoring of water equivalent using the snow pillow can help in updating the model but preferential melting from the pillow can be a problem. The energy budget melt formulation proves useful in understanding the energy components of melt typical of upland Britain. It reveals that, during the main melt phase, melt can occur in almost equal measure by sensible heat exchange and by latent heat of condensation, as warm air near saturation in cloud condenses on the snowpack; net radiation makes a negligible contribution. This provides a physical explanation for the success of the simple temperature excess approach to snowmelt estimation."
"57206357820;7003633691;7202422359;7007039835;","An optimal model output calibration algorithm suitable for objective temperature forecasting",1999,"10.1175/1520-0434(1999)014<0190:AOMOCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033117924&doi=10.1175%2f1520-0434%281999%29014%3c0190%3aAOMOCA%3e2.0.CO%3b2&partnerID=40&md5=bb159756f2cccd3e4b3e81f0449fffb3","An optimal model output calibration (MOC) algorithm suitable for surface air temperature forecasts was tested with the National Centers for Environmental Protection (NCEP) Regional Spectral Model (RSM). Numerical forecast experiments were conducted for six major urban centers in the Tennessee Valley, BNA, CHA, HSV, MEM, TRI, and TYS, over the period of 27 June to 30 July 1997. Forecasts of 2-m air temperature out to 72 h were produced based on RMS runs initialized at 0000 UTC. Performance of the MOC was assessed using the measures BIAS, MAE, and rmse relative to RSM. A skill core was calculated to quantify the improvement of refined RSM predictions over those of nonadjusted RSM. Results demonstrated that the forecast skill of the RSM was significantly improved with the use of the MOC.An optimal model output calibration (MOC) algorithm suitable for surface air temperature forecasts is proposed and tested with the National Centers for Environmental Prediction Regional Spectral Model (RSM). Differing from existing methodologies and the traditional model output statistics (MOS) technique, the MOC algorithm uses forecasts and observations of the most recent 2-4 weeks to objectively estimate and adjust the current model forecast errors and make refined predictions. The MOC equation, a multivariate linear regression equation with forecast error being the predictand, objectively screens as many as 30 candidates of predictors and optimally selects no more than 6. The equation varies from day to day and from site to site. Since it does not rely on long-term statistics of stable model runs, the MOC minimizes the influence of changes in model physics and spatial resolution on the forecast refinement process. Forecast experiments were conducted for six major urban centers in the Tennessee Valley over the period of 27 June to 30 July 1997. Surface air temperature forecasts out to 72 h were produced based upon RSM runs initialized from 0000 UTC observations. Performance of the MOC for minimum and maximum temperature forecasts was assessed by determining mean forecast error (BIAS), mean absolute error (MAE), and root-mean-square errors (rmse) for both the MOC-adjusted and nonadjusted RSM output. The same statistical measures for Nested Grid Model-MOS forecasts over the experiment period were also provided for instruction. A skill score was calculated to demonstrate the improvement of refined forecasts with the MOC over the RSM. On average for the six sites, reduction of forecast errors by the MOC ranged from 58% to 98% in BIAS, 40% to 52% in MAE, and 33% to 46% in rmse. It also showed that the error frequencies of the refined forecasts had Gaussian distributions with the peak centered around zero. The error bands were narrower using the MOC and there were decreases in large forecast errors, especially during the first 48 h. The Wilcoxon signed-rank test was performed to verify that populations of the forecast errors before and after the MOC adjustment were statistically far enough apart to be distinct at a high significance level. Forecast experiments were also conducted to address the issue of sensitivity of the MOC by varying the length of the time series used in deriving the MOC equation. It was found that the mean biases of the refined forecasts slightly increased and the MAE and rmse slightly decreased with increasing length of the time series from 2 to 4 weeks. The study demonstrated the usefulness of the MOC for objective temperature forecasting, especially in an operational environment in which changes in model physics and configurations are continually implemented and no long-term stable model runs are readily available to generate MOS forecast guidance. The MOC is also informative for diagnosing and tuning model physics. The study suggests that the MOC may be applied to other weather forecast elements, such as precipitation, cloud cover, visibility, and wind speed direction."
"7201504886;25953950400;7003591311;7004061048;","Large-eddy simulations of strongly precipitating, shallow, stratocumulus-topped boundary layers",1998,"10.1175/1520-0469(1998)055<3616:LESOSP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033489845&doi=10.1175%2f1520-0469%281998%29055%3c3616%3aLESOSP%3e2.0.CO%3b2&partnerID=40&md5=92c296ef389ff41576279d2650863711","Large-eddy simulations that incorporate a size-resolving representation of cloud water are used to study the effect of heavy drizzle on PBL structure. Simulated surface precipitation rates average about 1 mm day-1. Heavily drizzling simulations are compared to nondrizzling simulations under two nocturnal PBL regimes - one primarily driven by buoyancy and the other driven equally by buoyancy and shear. Drizzle implies a net latent heating in the cloud that leads to sharp reductions to both entrainment and the production of turbulent kinetic energy by buoyancy (particulariy in downdrafts). Drizzle, which evaporates below cloud base, promotes a cooler and moister subcloud layer that further inhibits deep mixing. The cooling and moistening is in quantitative agreement with some observations and is shown to favuor the formation of cumuli rising out of the subcloud layer. The cumuli, which are local in space and time, are responsible for most of the heat and moisture transport. They also appear to generate a larger-scale circulation that differs dramatically from the regularity typically found in nonprecipitating stratocumulus. Time-averaged turbulent fluxes of heat and moisture increase in the presence of precipitation, suggesting that drizzle (and drizzle-induced stratification) should not necessarily be taken as a sign of decoupling. Because drizzle primarily affects the vertical distribution of buoyancy, shear production of turbulent kinetic energy mitigates some of the effects described above. Based on large-eddy simulation the authors hypothersize that shallow, well-mixed, radiatively driven stratocumulus cannot persist in the presence of heavy drizzle. In accord with some simpler models, the simulated case with heavy percipitation promotes a reduction in both liquid-water path and entrainment. However, the simulations suggest that time-intergrated cloud fraction may increase as a result of drizzle because thinner percipitating clouds may persist longer if the boundary layer does not deepen as rapidly. These somewhat more complicated dynamics have important implications for a number of hypotheses suggesting that changes in acrosol concerntrations, when metabolized by stratocumulus, have a significant effort on climate."
"7005137442;7006861646;","Evidence for control of atlantic subtropical humidity by large scale advection",1998,"10.1029/1998GL900203","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032534914&doi=10.1029%2f1998GL900203&partnerID=40&md5=a4f8389924c89fd6e4d23907bd425134","The interplay between large scale dynamics and tropospheric moisture is investigated. A simple conceptual model of the sources and sinks of humidity is used to reconstruct, using a backward Lagrangian trajectory technique, the water vapor distribution in the tropical and subtropical free troposphere. Satellite data in the water vapor channel from both Meteosat-3 and Meteosat-4 satellites are then used to validate the model following a model-to-satellite approach over the whole Atlantic ocean. There is excellent agreement between simulations and observations in the drier regions, but the simulated brightness temperature exhibits a warm bias within and near moist, convective regions. This bias is most probably due to the neglect of cloud effects in reconstructing the simulated brightness temperature, rather than to a dry bias in the simulation. A second advective simulation, performed with monthly mean rather than full transient winds, led to a substantially drier subtropics. This calculation demonstrates the importance of synoptic scale transient eddies in determining the humidity of the subtropical dry zones. It is speculated on this basis that discontinuous changes in synoptic eddy activity could provide a mechanism for rapid global climate changes.The interplay between large scale dynamics and tropospheric moisture is investigated. A simple conceptual model of the sources and sinks of humidity is used to reconstruct, using a backward Lagrangian trajectory technique, the water vapor distribution in the tropical and subtropical free troposphere. Satellite data in the water vapor channel from both Meteosat-3 and Meteosat-4 satellites are then used to validate the model following a model-to-satellite approach over the whole Atlantic ocean. There is excellent agreement between simulations and observations in the drier regions, but the simulated brightness temperature exhibits a warm bias within and near moist, convective regions. This bias is most probably due to the neglect of cloud effects in reconstructing the simulated brightness temperature, rather than to a dry bias in the simulation. A second advective simulation, performed with monthly mean rather than full transient winds, led to a substantially drier subtropics. This calculation demonstrates the importance of synoptic scale transient eddies in determining the humidity of the subtropical dry zones. It is speculated on this basis that discontinuous changes in synoptic eddy activity could provide a mechanism for rapid global climate changes."
"7004325649;7004286811;7201826462;6701859365;34770543000;6603685334;54680987900;7006783796;56114842800;7403531523;7404150761;7005070958;7102290666;6701712843;7103271625;7005516084;35468686100;7406228987;13406672500;7202208382;7003899619;7201914101;","Clouds and the earth's radiant energy system (CERES): Algorithm overview",1998,"10.1109/36.701020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032120049&doi=10.1109%2f36.701020&partnerID=40&md5=0831cfefdcc809d7dffd1f55d6309aec","The Clouds and the Earth's Radiant Energy System (CERES) is part of NASA's Earth Observing System (EOS). CERES objectives include the following. 1) For climate change analysis, provide a continuation of the Earth Radiation Budget Experiment (ERBE) record of radiative fluxes at the top-of-the-atmosphere (TOA), analyzed using the same techniques as the existing ERBE data. 2) Double the accuracy of estimates of radiative fluxes at TOA and the earth's surface; 3) Provide the first long-term global estimates of the radiative fluxes within the earth's atmosphere. 4) Provide cloud property estimates collocated in space and time that are consistent with the radiative fluxes from surface to TOA. In order to accomplish these goals, CERES uses data from a combination of spaceborne instruments: CERES scanners, which are an improved version of the ERBE broadband radiometers, and collocated cloud spectral irnager data on the same spacecraft. The CERES cloud and radiative flux data products should prove extremely useful in advancing the understanding of cloud-radiation interactions, particularly cloud feedback effects on the earth's radiation balance. For this reason, the CERES data should be fundamental to our ability to understand, detect, and predict global climate change. CERES results should also be very useful for studying regional climate changes associated with deforestation, desertification, anthropogenic aerosols, and El Nino/Southern Oscillation events. This overview summarizes the Release 2 version of the planned CERES data products and data analysis algorithms. These algorithms are a prototype for the system that will produce the scientific data required for studying the role of clouds and radiation in the earth's climate system. This release will produce a data processing system designed to analyze the first CERES data, planned for launch on Tropical Rainfall Measuring Mission (TRMM) in November 1997, followed by the EOS morning (EOSAMI) platform in 1998. © 1998 IEEE."
"35271129900;7404232143;55713585900;55388515800;7501797728;","Studies on climate change in China in recent 45 years",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0005762904&partnerID=40&md5=1f2e66089550dd804e247b36747f57c7","Based on the data of monthly mean air temperature and precipitation from about 400 stations in 1951-1995, and the data of maximum and minimum air temperatures, relative humidity, total cloud cover and low-cloud cover, sunshine duration, evaporation, wind speed, snow-covered days and depth, and soil temperatures in 8 layers from 0 m down to 3.2 m from 200 odd stations in 1961-1995. the climate change and its characteristics in China in recent 45 years have been analyzed and studied comprehensively. This paper, as the first part of the work, has analyzed the climate change and regularities of such meteorological elements as mean air temperature, maximum and minimum air temperatures, precipitation, relative humidity and sunshine duration. The possible mechanism on climate change in China and the climate change and regularities of other meteorological elements will be discussed in another paper as the second part."
"7005069415;7004215477;35552141500;7006497723;7004923073;6505867984;","Scavenging of atmospheric constituents in mixed phase clouds at the high-alpine site Jungfraujoch - Part I: Basic concept and aerosol scavenging by clouds",1998,"10.1016/S1352-2310(98)00051-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032401432&doi=10.1016%2fS1352-2310%2898%2900051-X&partnerID=40&md5=b7329faf422e4785bb33b2353b897790","Extensive field experiments were performed in April/May 1992 and October/November 1993 in order to investigate the aerosol-cloud relationship at the high-alpine site Jungfraujoch, 3450 m asl. Aerosol and cloudwater samples were collected simultaneously and analyzed for the major water- soluble anions and cations. In addition, the cloud liquid water content (LWC) and the aerosol size distribution were measured. A nearly complete activation of particles with diameter d ≥ 0.2 lain was observed, independent of the number concentration. Since there was only a slight variability of the LWC, it was concluded that higher aerosol concentrations at high-alpine sites are associated with smaller droplet sizes. Long-term measurements of LWC and of the aerosol concentration suggested that this may be true throughout the year, giving additional evidence for a possible impact of anthropogenic aerosols on cloud albedo.Extensive field experiments were performed in April/May 1992 and October/November 1993 in order to investigate the aerosol-cloud relationship at the high-alpine site Jungfraujoch, 3450 m asl. Aerosol and cloudwater samples were collected simultaneously and analyzed for the major water-soluble anions and cations. In addition, the cloud liquid water content (LWC) and the aerosol size distribution were measured. A nearly complete activation of particles with diameter d≥0.2 μm was observed, independent of the number concentration. Since there was only a slight variability of the LWC, it was concluded that higher aerosol concentrations at high-alpine sites are associated with smaller droplet sizes. Long-term measurements of LWC and of the aerosol concentration suggested that this may be true throughout the year, giving additional evidence for a possible impact of anthropogenic aerosols on cloud albedo."
"7005196173;","How and why does antarctic sea -ice vary?",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031814787&partnerID=40&md5=3030b36368fe746b553f60570d39e6d9","This research looking at the role of Antarctic sea-ice/ocean coupling in global climate change on the interannual timescale has involved: (1) Composing a more accurate time series of Antarctic sea-ice extent back as far as the homogeneous satellite record allows. (2) Statistically comparing this record with spatially-gridded temporal data of relevant climatological variables for the high-latitude Southern Ocean, including surface pressure, temperature, wind speed, precipitation and cloud cover, and searching for any present trends or correlations. The principal results of this Ph.D. research are summarised here."
"7102604282;7201496259;7201699997;","Climate forcing by carbonaceous and sulfate aerosols",1998,"10.1007/s003820050259","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032446632&doi=10.1007%2fs003820050259&partnerID=40&md5=854258cfa43d41f235c55ab80c7f0428","An atmospheric general circulation model is coupled to an atmospheric chemistry model to calculate the radiative forcing by anthropogenic sulfate and carbonaceous aerosols. The latter aerosols result from biomass burning as well as fossil fuel burning. The black carbon associated with carbonaceous aerosols is absorbant and can decrease the amount of reflected radiation at the top-of-the-atmosphere. In contrast, sulfate aerosols are reflectant and the amount of reflected radiation depends nonlinearly on the relative humidity. We examine the importance of treating the range of optical properties associated with sulfate aerosol at high relative humidities and find that the direct forcing by anthropogenic sulfate aerosols can decrease from -0.81 W m-2 to -0.55 Wm-2 if grid box average relative humidity is not allowed to increase above 90%. The climate forcing associated with fossil fuel emissions of carbonaceous aerosols is calculated to range from +0.16 to +0.20 Wm-2, depending on how much organic carbon is associated with the black carbon from fossil fuel burning. The direct forcing of carbonaceous aerosols associated with biomass burning is calculated to range from -0.23 to -0.16 Wm-2. The pattern of forcing by carbonaceous aerosols depends on both the surface albedo and the presence of clouds. Multiple scattering associated with clouds and high surface albedos can change the forcing from negative to positive."
"6506537419;6602601219;7404061081;","Variations in satellite-derived precipitation estimates and atmospheric circulation over Africa",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032445610&partnerID=40&md5=b6c9d78d74dc4db29766a8b0bc0924f0","Temporal and spatial variability of precipitation estimates are compared to features of the atmospheric circulation for the African continent. The precipitation estimates are primarily based on cold cloud top duration obtained from METEOSAT 6 data, and are refined using an optimal interpolation of observed precipitation, surface topography, and numerical model forecasts of wind and relative humidity. These precipitation estimates are produced operationally at the Climate Prediction Center (CPC) for the United States Agency for International Development (USAID), in support of the drought monitoring efforts for the African continent as a part of the Famine Early Warning System (FEWS) activity. The NCEP Climate Data Assimilation System (CDAS) analyses of atmospheric fields are used to determine the flow regimes for selected cases. The temporal and spatial variability of the model analyses for monthly periods are examined to determine the possible dynamic links with precipitation anomalies for the African continent. Extreme precipitation events during the 1997 ENSO event are examined to evaluate differences in circulation patterns.Temporal and spatial variability of precipitation estimates are compared to features of the atmospheric circulation for the African continent. The precipitation estimates are primarily based on cold cloud top duration obtained from METEOSAT 6 data, and are refined using an optimal interpolation of observed precipitation, surface topography, and numerical model forecasts of wind and relative humidity. These precipitation estimates are produced operationally at the Climate Prediction Center (CPC) for the United States Agency for International Development (USAID), in support of the drought monitoring efforts for the African continent as a part of the Famine Early Warning System (FEWS) activity. The NCEP Climate Data Assimilation System (CDAS) analyses of atmospheric fields are used to determine the flow regimes for selected cases. The temporal and spatial variability of the model analyses for monthly periods are examined to determine the possible dynamic links with precipitation anomalies for the African continent. Extreme precipitation events during the 1997 ENSO event are examined to evaluate differences in circulation patterns."
"6701464156;","Features of long-term variations of atmospheric transparency coefficient and components of solar radiation in Siberia and the Far East in 1967-1986",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032463868&partnerID=40&md5=4ed3ab83c90f87f5b1f7d5d9365f51e2","The statistical analysis of time series of the atmospheric transparency coefficient, midday direct and total radiation, and winter, summer, and annual amounts of radiation is conducted using ground-based actinometric observations in summer and winter months from 1967-1986. Particularities of long-term variations of atmospheric transparency were analyzed jointly with daytime observations of air temperature changes and cloud amounts at the same stations. The statistically significant decrease in atmospheric transparency is found for summer and winter conditions at most stations in Siberia and Far East by a remarkable rise of air temperature in that period."
"55722053200;7401509344;","Land-surface-atmosphere interactions associated with deep convection in Illinois",1998,"10.1002/(SICI)1097-0088(199812)18:15<1637::AID-JOC336>3.0.CO;2-U","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032454723&doi=10.1002%2f%28SICI%291097-0088%28199812%2918%3a15%3c1637%3a%3aAID-JOC336%3e3.0.CO%3b2-U&partnerID=40&md5=2145934a6c0507f701370c2db7e22943","Geostationary operational environmental satellite (GOES East) imagery are used to investigate a possbile spatial clustering of free convective cloud masses along land-cover-type boundaries in the state of Illinois on days with weak synoptic-scale flow. Soil moisture data and a surface cover-type classification system are employed to identify likely cloud formation zones (as a function of non-classical mesoscale circulations (NCMCs)) forced by heterogeneous surface fluxes of sensible and latent heat. The emphasis of this research is on documenting the existence of convective cloud clusters and determining locations where they would be expected to occur if land-surface-atmosphere forcing were involved. This research shows that a statistically significant spatial clustering of free convective cloud masses does exist, and that these clusters occur along land-cover-type and soil-order boundaries. The three most conspicuous locations for both the initiation and vertical enhancement of convective clouds are along: (i) the agricultural and mixed forest-agricultural boundary that extends west-east from near St. Louis, Missouri, to Terre Haute, Indiana; (ii) along the urban/suburban Chicago metropolitan area and agricultural boundary in northeast Illinois; and (iii) along the agricultural and agricultural-mixed forest boundary along the Illinois River in east-central Illinois. It is also apparent from composite rawinsonde soundings that a majority of free convective cloud masses develop along land-cover-type boundaries on weak synoptic-scale flow days when planetary boundary layer moisture levels are large. This provides further support for the proposal that non-classical mesoscale circulations (NCMCs) provide the mass convergence necessary to force moist air parcels to the level of free convection along land-cover-type boundaries. These results also suggest that human-modification of the Earth's surface may play a significant role in local-scale climate change."
"7102953444;57202413846;7003630824;7003979342;6603247427;24322005900;","The disposition of radiative energy in the global climate system: GCM-calculated versus observational estimates",1998,"10.1007/s003820050260","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032433727&doi=10.1007%2fs003820050260&partnerID=40&md5=f1f598b39e9d78eb4c60b210cb347257","A comprehensive dataset of direct observations is used to assess the representation of surface and atmospheric radiation budgets in general circulation models (GCMs). Based on combined measurements of surface and collocated top-of-the-atmosphere fluxes at more than 700 sites, a lack of absorption of solar radiation within the atmosphere is identified in the ECHAM3 GCM, indicating that the shortwave atmospheric absorption calculated in the current generation of GCMs, typically between 60 and 70 Wm-2, is too low by 10-20 Wm-2. The surface and atmospheric radiation budgets of a new version of the Max-Planck Institute GCM, the ECHAM4, differ considerably from other GCMs in both short- and longwave ranges. The amount of solar radiation absorbed in the atmosphere (90 Wm-2) is substantially larger than typically found in current GCMs, resulting in a lower absorption at the surface (147 Wm-2). It is shown that this revised disposition of solar energy within the climate system generally reduces the biases compared to the observational estimates of surface and atmospheric absorption. The enhanced shortwave absorption in the ECHAM4 atmosphere is due to an increase in both simulated clear-sky and cloud absorption compared to ECHAM3. The increased absorption in the cloud-free atmosphere is related to an enhanced absorption of water vapor, and is supported in stand-alone comparisons of the radiation scheme with synchronous observations. The increased cloud absorption, on the other hand, is shown to be predominantly spurious due to the coarse spectral resolution of the ECHAM4 radiation code, thus providing no physical explanation for the 'anomalous cloud absorption' phenomenon. Quantitatively, however, an additional increase of atmospheric absorption due to clouds as in ECHAM4 is, at least at low latitudes, not in conflict with the observational estimates, though this does not rule out the possibility that other effects, such as highly absorbing aerosols, could equally contribute to close the gap between models and observations. At higher latitudes, however, the increased cloud absorption is not supported by the observational dataset. Overall, this study points out that not only the clouds, but also the cloud-free atmosphere might be responsible for the discrepancies between observational and simulated estimates of shortwave atmospheric absorption. The smaller absorption of solar radiation at the surface in ECHAM4 is compensated by an increased downward longwave flux (344 Wm-2), which is larger than in other GCMs. The enhanced downward longwave flux is supported by surface measurements and by a stand-alone validation of the radiation scheme for clear-sky conditions. The enhanced flux also ensures that a sufficient amount of energy is available at the surface to maintain a realistic intensity of the global hydrological cycle. In contrast, a one-handed revision of only the shortwave radiation budget to account for the increased shortwave absorption in GCM atmospheres may induce a global hydrological cycle that is too weak."
"35464731600;7004537925;6603314967;8266492600;","Earth observing system AMI mission to earth",1998,"10.1109/36.700989","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032117022&doi=10.1109%2f36.700989&partnerID=40&md5=be87db13ae6e813aea98cdfa0f5d70fa","In 1998, NASA launches EOS-AMI, the first of a series of the Earth Observing System (EOS) satellites. EOS will monitor the evolution of the state of the earth for 18 years, starting with the morning observations of EOS-AMI (10:30 a.m. equatorial crossing time). An integrated view of the earth, as planned by EOS, is needed to study the interchange of energy, moisture, and carbon between the lands, oceans, and atmosphere. The launch of EOS-AMI and other international satellites marks a new phase of climate and global change research. Both natural and anthropogenic climate change have been studied for more than a century. It is now recognized that processes that vary rapidly in time and space-e.g., aerosol, clouds, land use, and exchanges of energy and moisture-must be considered to adequately explain the temperature record and predict future climate change. Frequent measurements with adequate resolution, as only possible from spacecraft, are key tools in such an effort. The versatile and highly accurate EOSAMI data, together with previous satellite records, as well as data from the Advanced Earth Observing System (ADEOS) (I and II), Tropical Rainfall Measuring Mission (TRMM), Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Along Track Scanning Radiometer (ATSR), Medium Resolution Imaging Spectrometer (MERIS), Environmental Satellite (ENVISAT), EOS-PM1, Land Remote-Sensing Satellite (Landsat), and ground-based networks is expected to revolutionize the way scientists look at climate change. This article introduces the EOS-AMI mission and the special issue devoted to it. Following a brief historical perspective for an insight into the purpose and objectives of the mission, we shall summarize the characteristics of the five instruments onboard EOS-AMI. Specifically, we concentrate on the innovative elements of these five instruments and provide examples of the science issues that require this type of data. These examples show the importance of collecting data simultaneously from each of the five EOS-AMI sensors for studying rapidly varying processes and parameters."
"6601942466;7005893321;6506392154;16413934500;","Scavenging efficiency of lead and sulfate in supercooled clouds at Sonnblick, 3106 m a.s.l., Austria",1998,"10.1016/S1352-2310(98)00148-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032403773&doi=10.1016%2fS1352-2310%2898%2900148-4&partnerID=40&md5=b87be8be68745a54c8233d96c234bde9","During three field campaigns at Mt. Sonnblick (3106 m, Salzburg, Austria), in winter 1991, summer 1992 and summer 1993, a comprehensive study of cloud water chemistry, snow chemistry and interstitial gas and aerosol constituents was performed. In this work we report on the in-cloud scavenging efficiency of lead (ε(Pb)) and sulfate (ε(SO4)). Due to its similar size distribution to sulfate, we used lead as an inert aerosol tracer for the calculation of the scavenging efficiency of particulate sulfate (ε(SO4)/(*)). At the experimental site (Sonnblick Observatory, 3106 m, Salzburg, Austria) clouds appear frequently in the mixed state with suspended supercooled liquid droplets and precipitating ice crystals. Here we examine the transfer of lead, sulfate and sulfur dioxide from the interstitial phase to the supercooled cloud droplets. The aerosol scavenging efficiency for lead (ε(Pb)) ranges from 0.1 to 0.97 and is a function of the liquid water content (LWC) of the supercooled droplet phase of the cloud. At low LWCs, ε(Pb) increases from 0.1 to 016. Above LWCs of 0.3 g m-3, ε(Pb) remains relatively constant at about 0.85. Calculating the scavenging efficiency for sulfate (ε(SO4)) a similar dependency could be obtained. The scavenging efficiency ranges from 0.17 to 0.96. Up to a LWC of 0.3 g m-3 an increase of ε(SO4) was observed. At higher LWCs it remains relatively constant at about 0.8. Aerosol scavenging of sulfate was found to be the predominant source for cloud water sulfate. Only during eight out of 33 sampling intervals a significant contribution (7-85%) of gas phase scavenging of sulfur dioxide could be determined. LWCs in November were very low, ranging from 0.01-0.1 g m-3 with an average of 0.047 g m-3. LWCs in June ranged from 0.05 to 0.63 g m-3 with an average of 0.35 g m-3. In May and June 1993 LWCs ranged from 0.08 to 0.782 g m-3 with an average of 0.28 g m-3.During three field campaigns at Mt. Sonnblick (3106 m, Salzburg, Austria), in winter 1991, summer 1992 and summer 1993, a comprehensive study of cloud water chemistry, snow chemistry and interstitial gas and aerosol constituents was performed. In this work we report on the in-cloud scavenging efficiency of lead (εPb) and sulfate (εSO(4)). Due to its similar size distribution to sulfate, we used lead as an inert aerosol tracer for the calculation of the scavenging efficiency of particulate sulfate (ε*SO(4)). At the experimental site (Sonnblick Observatory, 3106 m, Salzburg, Austria) clouds appear frequently in the mixed state with suspended supercooled liquid droplets and precipitating ice crystals. Here we examine the transfer of lead, sulfate and sulfur dioxide from the interstitial phase to the supercooled cloud droplets. The aerosol scavenging efficiency for lead (εPb) ranges from 0.1 to 0.97 and is a function of the liquid water content (LWC) of the supercooled droplet phase of the cloud. At low LWCs, εPb increases from 0.1 to 0.6. Above LWCs of 0.3 g m-3, εPb remains relatively constant at about 0.85. Calculating the scavenging efficiency for sulfate (εSO(4)) a similar dependency could be obtained. The scavenging efficiency ranges from 0.17 to 0.96. Up to a LWC of 0.3 g m-3 an increase of εSO(4) was observed. At higher LWCs it remains relatively constant at about 0.8. Aerosol scavenging of sulfate was found to be the predominant source for cloud water sulfate. Only during eight out of 33 sampling intervals a significant contribution (7-85%) of gas phase scavenging of sulfur dioxide could be determined. LWCs in November were very low, ranging from 0.01-0.1 g m-3 with an average of 0.047 g m-3. LWCs in June ranged from 0.05 to 0.63 g m-3 with an average of 0.35 g m-3. In May and June 1993 LWCs ranged from 0.08 to 0.782 g m-3 with an average of 0.28 g m-3."
"7202972418;37043715000;","The influence of cloud cover on the radiation budget, physical properties, and microwave scattering coefficient (cr°) of first-year and multiyear sea ice",1998,"10.1109/36.655316","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031646488&doi=10.1109%2f36.655316&partnerID=40&md5=4b16d69b914cfccea7227e6254b5a401","Over sea ice, the shift from predominantly clear conditions in winter to persistent stratus cloud cover in late spring and early summer coincides with a dramatic increase in the net radiation balance at the sea ice surface. Transformation of the boundary layer climate and the geophysical properties of the snow covered sea ice result from this cloud-induced rise in surface energy balance. In this paper, in situ data from the Seasonal Sea Ice Monitoring the Modeling Site (SIMMS'93) experiment are used to examine the extent to which changes in surface radiation, sea ice physical and electrical properties, and microwave scattering are a function of clear versus cloudy conditions over first-year and multiyear sea ice types. We use the surface observations to drive a simple forward scattering model used to diagnose the potential mechanisms responsible for the observed changes in microwave scattering by the Earth Resources Satellite-1 (ERS-1). Our results indicate that under cloudy conditions the surface temperature increases because of the surplus in the longwave net radiative energy. This causes an increase in the surface temperature and formation of a temperature wave down through the snow volume into the ice surface. This increases the dielectric constant of the snow basal layer and ice surface over first-year sea ice because of the thin snow cover (relative to the thicker multiyear ice snow cover) and because of the temperature effect on brine volume. The observed increase in scattering is limited to very smooth first-year sea ice types. Models used to diagnose the principal scattering mechanisms suggest that the cloud cover effects the scattering either by creating a dielectrically rough basal layer in the snow volume near the ice surface or by increasing the scattering contribution from snow grains within the basal layer volume. Under either scenario the increase in scattering is small (~5 dB) and is only detectable if the target presents a scattering magnitude less than about -20 dB. © 1998 IEEE."
"7006061457;7005729142;","The theory of contrails",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032299982&partnerID=40&md5=34049d2dc6efed0cbd4663a60e9961d9","A well-known theory of aircraft contrails (proposed by Sadovnikov, Appleman, Khrgian, and Mazin) is generalized for the case where condensation starts at relative humidity below 100%. The Appleman parameter is replaced by a contrail parameter k. When relative humidity drops to 70%, the threshold (maximum) atmospheric temperature at which the formation of contrails is still possible rises by about 10°C compared with Appleman temperature. It is noteworthy that anthropogenic climate impact connected with the appearance of contrails behind aircraft is determined not only by the intensity of air flights, but also by the location, time, and frequency of formation of clear-sky metastable zones in which humidity is higher than ice saturation."
"6506591483;7003615192;6601942466;7005893321;","On-line measurements of sulfur dioxide at the 3 km level over Central Europe (Sonnblick Observatory, Austria) and statistical trajectory source analysis",1998,"10.1016/S1352-2310(98)00015-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032401414&doi=10.1016%2fS1352-2310%2898%2900015-6&partnerID=40&md5=b0155f808fc65592aca71ecd1c7786a8","Continuous sulfur dioxide (SO2) measurements were performed at the Sonnblick Observatory (SBO), Austria (3106 m a.s.l.) for several weeks during summer, autumn and spring 1995/96. The average SO2 concentration was 0.30 μg m-3 standard temperature and pressure (STP; 273 K, 1013 hPa) (105 pptv), the median 0.10μg m-3 STP (35 pptv). For 80% of the time sulfur dioxide concentrations were at 'clean levels' (&lt; 0.30μg m-3) interrupted by 'episodes' lasting up to two days. During the episodes SO2 levels rose generally above 0.5 μg m-3 and reached up to 8.0 μg m-3 in spring. Sulfur dioxide concentrations showed a strong seasonal variation with very low concentrations during summer and fall (means 0.11 and 0.17μg m-3) and elevated concentrations during spring (mean 0.70μg m-3). An analysis of the diurnal variation indicated that upslope winds are not responsible for the elevated SO2 levels observed during SO2 episodes; rather cloud transport appears to be the predominant process for lifting SO2 from the boundary layer to the mid troposphere. For air and cloud transport across Western European countries hydrogen peroxide (H2O2) is apparently in excess and most SO2 is removed by oxidation leading to 'lean conditions'. For the less frequent air and cloud transport from the East and Southeast SO2 appears to be in excess leading to the 'SO2 episodes' at the 3 km level. These results are substantiated by in-cloud observations of elevated levels of SO2 at SBO (Brantner et al., 1994) and trajectory statistics for the SO2 data set from SBO and analysis of the meteorological conditions during transport.Continuous sulfur dioxide (SO2) measurements were performed at the Sonnblick Observatory (SBO), Austria (3106 m a.s.l.) for several weeks during summer, autumn and spring 1995/96. The average SO2 concentration was 0.30 μg m-3 standard temperature and pressure (STP; 273 K, 1013 h Pa) (105 pptv), the median 0.10 μg m-3 STP (35 pptv). For 80% of the time sulfur dioxide concentrations were at `clean levels' (&lt;0.30 μg m-3) interrupted by `episodes' lasting up to two days. During the episodes SO2 levels rose generally above 0.5 μg m-3 and reached up to 8.0 μg m-3 in spring. Sulfur dioxide concentrations showed a strong seasonal variation with very low concentrations during summer and fall (means 0.11 and 0.17 μg m-3) and elevated concentrations during spring (mean 0.70 μg m-3). An analysis of the diurnal variation indicated that upslope winds are not responsible for the elevated SO2 levels observed during SO2 episodes; rather cloud transport appears to be the predominant process for lifting SO2 from the boundary layer to the mid troposphere. For air and cloud transport across Western European countries hydrogen peroxide (H2O2) is apparently in excess and most SO2 is removed by oxidation leading to `clean conditions'. For the less frequent air and cloud transport from the East and Southeast SO2 appears to be in excess leading to the `SO2 episodes' at the 3 km level. These results are substantiated by in-cloud observations of elevated levels of SO2 at SBO and trajectory statistics for the SO2 data set from SBO and analysis of the meteorological conditions during transport."
"7401481611;7006366653;7402456930;13310165300;","Precipitation decrease in the western Arctic, with special emphasis on Barrow and Barter Island, Alaska",1998,"10.1002/(SICI)1097-0088(199812)18:15<1687::AID-JOC341>3.0.CO;2-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032462329&doi=10.1002%2f%28SICI%291097-0088%28199812%2918%3a15%3c1687%3a%3aAID-JOC341%3e3.0.CO%3b2-2&partnerID=40&md5=39ddf5becbea71569a4a3a431dc0cbee","Over the Arctic during the last few decades a decrease in annual precipitation and snow depths have been observed; this decrease is especially pronounced during the winter months. This decrease was not only found over northern Alaska but also over the high latitude Canadian stations and Russian drift stations. Further, satellite monitoring of North America snow cover has revealed a significant decreasing trend in mid-spring cover since 1972. The temperature increased during the last few decades in the Arctic, hence the simplest explanation-normally increased temperature leads to high precipitation-is not valid. A causal explanation for these trends had been related to the shift of the Aleutian low and Arctic high. This study, with special emphasis on the surface observation data from Barrow and Barter Island, indicates: (i) not only the frequency, but the mean intensity of precipitation has decreased; (ii) the amount of total cloud cover, and in particular, low cloudiness, has decreased with time; (iii) sea-level pressure did not show any significant trends. Variability in atmospheric pressure, however, decreased with time, suggesting that either the intensity and/or frequency of cyclones has decreased; (iv) a shift in seasonal resultant winds at Barrow has been observed."
"6602189469;","Medium-term cloudiness variation within the area of the city of Dubrovnik - processes in the period from 1987 until 1997",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032469653&partnerID=40&md5=5bb5a8d57a438b2a3c0414c4421ce370","Medium-term cloudiness variations in the area of the city of Dubrovnik point out that in the period from 1987 until 1997 the cloudiness was reduced by about 15%. The climatic average is 4, 6 and the medium-term one is 4, 0 measured in tenths. In the first five-year period from 1987 until 1991 the cloudiness was 3, 8 and during the second from 1992 until 1997 it was 4, 2. In the course of seven years the cloudiness was below medium-term climatic average, during one year above medium-term (below climatic) and for two year above the climatic average. Reconsidering observations of the annual, seasonal and daily cloudiness and precipitation values, the area of the city of Dubrovnik can be determined as a stable and a dynamic one."
"7102224078;7004507219;55454865100;7202803069;","Rainfall monitoring in the humid tropics using a multisource method",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032426754&partnerID=40&md5=9cbe5b22d50135d65cb8e5609ab32129","Historically, rainfall has been measured by in situ devices, principally by raingauges, and since World War II, by rainfall radar. In the 1970s and 1980s growing interest was paid to the potential of satellite data, particularly infrared and passive microwave imagery, for such purposes. Today, informed attention is focusing increasingly upon the advantages to be gained from combinations of data from as many different sources as possible. After a general introduction, this paper describes and explains a rainfall monitoring method development strategy initiated by the Centre for Remote Sensing, Bristol, UK in 1991, involving climate data sets, synoptic weather reports, satellite infrared and passive microwave data, and other GIS database information. Results have been obtained from several major areas of the humid tropics over periods of up to five years, leading to much improved understanding of the cloud-rainfall relationships and the estimation models themselves. The Bristol methodology has been designed to be operable in real time, flexible in its response to end-user product requirements, and widely applicable through its use of data sets available on the Internet. The paper concludes with a summary of further methodological and related research and development planned for this on-going project, elements of which are already in operational use in support of some humid tropical regions.Historically, rainfall has been measured by in situ devices, principally by raingauges, and since World War II, by rainfall radar. In the 1970s and 1980s growing interest was paid to the potential of satellite data, particularly infrared and passive microwave imagery, for such purposes. Today, informed attention is focusing increasingly upon the advantages to be gained from combinations of data from as many different sources as possible. After a general introduction, this paper describes and explains a rainfall monitoring method development strategy initiated by the Centre for Remote Sensing, Bristol, UK in 1991, involving climate data sets, synoptic weather reports, satellite infrared and passive microwave data, and other GIS database information. Results have been obtained from several major areas of the humid tropics over periods of up to five years, leading to much improved understanding of the cloud-rainfall relationships and the estimation models themselves. The Bristol methodology has been designed to be operable in real time, flexible in its response to end-user product requirements, and widely applicable through its use of data sets available on the Internet. The paper concludes with a summary of further methodological and related research and development planned for this on-going project, elements of which are already in operational use in support of some humid tropical regions."
"6602964178;7003828850;","A case study of the synoptic patterns influencing midwinter snowmelt across the northern Great Plains",1998,"10.1002/(SICI)1099-1085(199812)12:15<2293::AID-HYP797>3.0.CO;2-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032447973&doi=10.1002%2f%28SICI%291099-1085%28199812%2912%3a15%3c2293%3a%3aAID-HYP797%3e3.0.CO%3b2-9&partnerID=40&md5=d5f711cf38262c8be6244833bd0e5923","Snow cover is found across extensive areas of the northern hemisphere during the winter and early spring seasons. Meltwater provided by this snow cover can be an important source of freshwater for agriculture, domestic uses and hydroelectric power. Rapid ablation of the snowpack, however, can also pose environmental hazards such as flooding. The ability to forecast meltwater quantities is dependent upon a knowledge of the factors influencing the snowmelt process. This paper employs a hybrid modelling and synoptic climatological approach to investigate the relationships between synoptic weather patterns, surface energy fluxes and midwinter snowmelt in the northern Great Plains. The first objective of this study is to identify distinct synoptic patterns that are associated with days where significant snow cover ablation occurred. The second objective is to evaluate the relationships between synoptic-scale weather patterns, snow surface energy transfers and snowmelt. A case study of 21 February 1975 is used to illustrate these relationships. Unlike the other synoptic-type studies, which rely on empirically derived energy flux data from single index sites, this study employs a physically based snowpack model to generate estimates of energy fluxes. The use of modelled fluxes instead of measured values allows for a more spatially extensive analysis as surface fluxes over the entire study region can be analysed in conjunction with the prevailing synoptic-scale weather patterns. Three major synoptic types, characterized by the presence of a midlatitude cyclone, are associated with large midwinter snowmelt episodes in the northern Great Plains. The case study illustrates how variations in temperature, humidity, cloud cover and wind speeds associated with such cyclonic storms can play a major role in affecting snow surface-atmosphere energy exchanges. As expected, elevated wind speeds and stronger temperature and humidity gradients significantly increased the transfers of sensible and latent heat between the snow surface and the atmosphere. Increased cloud cover near the low pressure centre reduced incoming solar radiation but through counter radiation also reduced the loss of long-wave radiation.A hybrid modeling and synoptic climatological approach was employed to study the relationships between synoptic weather patterns, surface energy fluxes and midwinter snowmelt in the northern Great Plains. The study illustrates how variations in temperature, humidity, cloud cover and wind speeds associated with cyclonic storms can play a major role in affecting snow surface-atmosphere energy exchanges. As expected, elevated wind speeds and stronger temperature and humidity gradients significantly increased the transfers of sensible and latent heat between snow surface and temperature. Increased cloud cover near the low pressure center reduced incoming solar radiation but through counter radiation also reduced the loss of long-wave radiation."
"6701891391;6602108591;7006681376;","Mean long-term surface energy balance components in Finland during the summertime",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-3042994473&partnerID=40&md5=7d863bc6439fc9c453a3185c5268ef8d","The long-term, 1961-1990, mean summertime surface energy balance components in Finland were estimated by making use of earlier published studies for the estimation of the global radiation, surface albedo and latent heat flux. The net long-wave radiation was estimated with the help of synoptic cloud observations, and the sensible heat flux was calculated as the remainder in the energy balance equation. The results are presented both on a 10 km × 10 km grid and as climate-zone averages. The lowest values of global radiation, about 170 W m-2, were found in north-eastern Lapland. There was also a local minimum of about 190 W m-2 over the Suomenselkä divide and southern Ostrobothnia. The maximum values of about 220 W m-2 were found along the coast of the Baltic Sea. The cooling of the surface due to net long-wave radiation was smallest in northern Lapland, about -35 W m-2, elsewhere the spatial variation was very small, and the net long-wave radiation was from -40 to -45 W m-2. The highest values of evaporation occured in southern Finland, where the latent heat flux was about -80 W m-2, and the minimum in Lapland with a value of about -35 W m-2. The highest sensible heat fluxes were located along the coast and in Lapland, and the smallest in the inland areas of southern Finland. The difference in the sensible heat flux between the climate zones was small."
"7408202424;7004286811;6602270954;6701712843;7003652120;35586221600;7006075455;56114842800;7404655255;6505576518;55740124200;","Prelaunch calibrations of the clouds and the earth's radiant energy system (CERES) tropical rainfall measuring mission and earth observing system morning (EOS-AMI) spacecraft thermistor bolometer sensors",1998,"10.1109/36.701024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032117671&doi=10.1109%2f36.701024&partnerID=40&md5=b3a7785626a48f7b4327eedd63d61249","The Clouds and the Earth's Radiant Energy System (CERES) spacecraft scanning thermistor bolometer sensors measure earth radiances in the broadband shortwave solar (0.3-5.0 fim) and total (0.3->100 /urn) spectral bands as well as in the 8-12-jum water vapor window spectral band. On November 27, 1997, the launch of the Tropical Rainfall Measuring Mission (TRMM) spacecraft placed the first set of CERES sensors into orbit, and 30 days later, the sensors initiated operational measurements of the earth radiance fields. In 1998, the Earth Observing System morning (EOS-AMI) spacecraft will place the second and third sensor sets into orbit. The prelaunch CERES sensors' count conversion coefficients (gains and zero-radiance offsets) were determined in vacuum ground facilities. The gains were tied radiometrically to the International Temperature Scale of 1990 (ITS-90). The gain determinations included the spectral properties (reflectance, transmittance, emittance, etc.) of both the sources and sensors as well as the in-field-of-view (FOV) and out-of-FOV sensor responses. The resulting prelaunch coefficients for the TRMM and EOS-AMI sensors are presented. Inflight calibration systems and on-orbit calibration approaches are described, which are being used to determine the temporal stabilities of the sensors' gains and offsets from prelaunch calibrations through on-orbit measurements. Analyses of the TRMM prelaunch and on-orbit calibration results indicate that the sensors have retained their ties to ITS-90 at accuracy levels better than ±0.3% between the 1995 prelaunch and 1997 on-orbit calibrations. © 1998 IEEE."
"6602744181;55722586400;55678879300;","Sources of systematic errors in the climatology of a regional climate model over Europe",1998,"10.1007/s003820050249","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032435734&doi=10.1007%2fs003820050249&partnerID=40&md5=13361cbebf95b136e05e2414f5aebc8f","Two 10-year simulations made with a European regional climate model (RCM) are compared. They are driven by the same observed sea surface temperatures but use different lateral boundary forcing. For one simulation, RCM ASSIM, it is derived from a time series of operational analyses. The archive of analysis fields (surface pressure plus winds and temperatures on various pressure levels) is not sufficiently comprehensive to provide directly the full set of driving fields required for the RCM (in particular, no moisture fields are present), so these are obtained via a GCM integration, GCM ASSIM, in which the model is continuously relaxed towards the analysis fields using a data assimilation technique. Errors in RCM AMIP can arise either from the internal RCM physics or from errors in the lateral boundary forcing inherited from GCM AMIP. Errors in RCM ASSIM can arise from the internal RCM physics or the boundary moisture forcing but not from the driving circulation. Although previous studies have considered RCM integrations driven either by output from standard GCM integrations or operational analyses, our study is the first to compare parallel integrations of each type. This allows the total systematic error in an RCM integration driven by standard GCM output to be partitioned into components arising from the driving circulation and the internal RCM physics. These components indicate the scope for reducing regional simulation biases by improving either the driving GCM or the RCM itself. The results relate mainly to elements of surface climate likely to be influenced by both the driving circulation and regional physical processes operating in the RCM. For cloud cover, errors are found to arise largely from the internal RCM physics. Values are too low despite a positive relative humidity bias, indicating shortcomings in the parametrisation scheme used to calculate cloud cover. In summer, surface temperature and precipitation errors are also explained principally by regional processes. For example excessive solar heating leads to anomalously high surface temperatures over southern Europe and excessive drying of the soil reduces precipitation in the south eastern sector of the domain. The lateral boundary forcing reduces precipitation in the south eastern sector of the domain. The lateral boundary forcing also exerts some influence, mainly via a tropospheric cold bias which partially offsets the warming over southern Europe and also increases precipitation. In other seasons the lateral boundary forcing and the regional physics both contribute significantly to the errors in surface temperature and precipitation. In winter the boundary forcing (apart from moisture) is responsible for about 60% of the total error variance for temperature and about 40% for precipitation, due to the cold bias and circulation errors such as a southward shift in the storm track. The remaining errors arise from the regional physics, although for precipitation an excessive supply of moisture from the lateral boundaries also contributes. The skill of the mesoscale component of the surface temperature and precipitation distributions exceeds previous estimates, due to more realistic observed climatology. The mesoscale patterns are very similar in the two RCM simulations indicating that errors in the simulation of fine scale detail arise mainly from inadequate representations of local forcings rather than errors in the large-scale circulation. Circulation errors in RCM AMIP (e.g. cold bias, southward shift of storm track) are also present in GCM AMIP, but are largely absent in RCM ASSIM except in summer. This confirms evidence from previous work that the key to reducing most circulation errors in the RCM lies in improving the driving GCM. Regional processes only make a major contribution to circulation errors in summer, when reduced advection from the boundaries allows errors in surface temperature to be transmitted more effectively into the troposphere. Finally, we find evidence of error balances in the GCM which act to minimise biases in important climatological variables. This reflects tuning of the model physics at GCM resolution. In order to achieve simultaneous optimisation of the RCM and GCM at widely differing resolutions it may be necessary to introduce explicit scale dependences into some aspects of the physics."
"34882516100;7007090761;6701805296;36947350200;6507710905;","Overview of advanced spaceborne thermal emission and reflection radiometer (ASTER)",1998,"10.1109/36.700991","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032119711&doi=10.1109%2f36.700991&partnerID=40&md5=e18fe155db02aecd394ca4b61291bad6","The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a research facility instrument provided by the Ministry of International Trade and Industry (MITI), Tokyo, Japan to be launched on NASA's Earth Observing System morning (EOS-AMI) platform in 1998. ASTER has three spectral bands in the visible near-infrared (VNIR), six bands in the shortwave infrared (SWIR), and five bands in the thermal infrared (TIR) regions, with 15-, 30-, and 90-m ground resolution, respectively. The VNIR subsystem has one backward-viewing band for stereoscopic observation in the along-track direction. Because the data will have wide spectral coverage and relatively high spatial resolution, we will be able to discriminate a variety of surface materials and reduce problems in some lower resolution data resulting from mixed pixels. ASTER will, for the first time, provide high-spatial resolution multispectral thermal infrared data from orbit and the highest spatial resolution surface spectral reflectance temperature and emissivity data of all of the EOS-AMI instruments. The primary science objective of the ASTER mission is to improve understanding of the local- and regional-scale processes occurring on or near the earth's surface and lower atmosphere, including surface-atmosphere interactions. Specific areas of the science investigation include the following: 1) land surface climatology; 2) vegetation and ecosystem dynamics; 3) volcano monitoring; 4) hazard monitoring; 5) aerosols and clouds; 6) carbon cycling in the marine ecosystem; 7) hydrology; 8) geology and soil; and 9) land surface and land cover change. There are three categories of ASTER data: a global map, regional monitoring data sets, and local data sets to be obtained for requests from individual investigators. The ASTER instrument will have a limited (8%) duty cycle. Prioritization of data acquisition requests will be based on such factors as data category, user category, and science discipline. © 1998 IEEE."
"7102821397;","Glaciers of South America- glaciers of Bolivia",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032324209&partnerID=40&md5=9d4c25518651c9d47219c8a0ac73130d","Present-day glaciers of Bolivia are restricted to the highest peaks of the Andes Mountains. In the Cordillera Occidental, the glaciers are found as crater glaciers, small summit ice caps, and outlet glaciers on the extinct volcanoes in the northern part of the country. Their total surface area is about 10 square kilometers. Most of the glaciers are located in the Cordillera Oriental in the Cordilleras Apolobamba, Real, and Tres Cruces and in Nevado Santa Vera Cruz as ice caps, valley glaciers, and mountain glaciers. Their surface area covers more than 550 square kilometers. Because of the limited precipitation, no glaciers exist in southern Bolivia. During the Pleistocene, glacierization was much more extensive. Presently glacierized areas were larger, and glaciers were also found in areas that no longer support permanent ice. In the Cordillera Occidental, terminal moraines have been found below the 4,500-meter elevation, and in the Cordillera Oriental, at slightly above 3,000 meters. In between, in the Altiplano, traces of glaciation rise 100-200 meters higher from the center to the margin of that area. The location, distribution, and mass-balance of Bolivian glaciers are the result of the climate and the orientation and elevation of its mountain ranges. In contrast to extratropical glaciers, accumulation takes place during the summer, and ablation takes place during the winter and interseasonal periods. The daily cloud-cover cycle, which leaves the glaciers exposed to morning solar radiation from the north and east and protects the western slopes in the afternoon, results in a substantially lower snowline on the western and southern slopes (100 to 300 meters lower). The glaciers of Bolivia are covered by maps, aerial photographs, and satellite images of varying degrees of usefulness. Accurate maps at 1:50,000 scale cover the Cordillera Real. Vertical aerial photographs having scales between 1:30,000 and 1:80,000 cover all the glacierized areas of Bolivia and range in quality from good to satisfactory. Satellite images with resolutions ranging from 5 to 79 meters are also available, and although they may be limited by resolution, cloudiness, shadowing, or spectral discrimination, they offer a useful tool for frequently monitoring glacier variation."
"56207315300;7004006601;7003875148;6701587775;","Regional surface fluxes over the NOPEX area",1998,"10.1016/S0022-1694(98)00207-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032432128&doi=10.1016%2fS0022-1694%2898%2900207-8&partnerID=40&md5=9cc05865e06da641a762d17128057179","The regional surface fluxes of sensible heat and moisture are estimated for two days during NOPEX '94 by means of aircraft measurements. A box flight pattern is analysed for 13 June (a weak wind case) and 14 June (a strong wind case), both with cold air advection. We perform a scale analysis in order to identify the main transporting scales of the turbulent fluxes and to investigate the mesoscale variability of the sensible heat and moisture flux. The example of a mesoscale moisture front indicates the importance of subgrid mesoscale variability. The turbulent fluxes of sensible heat and moisture are affected significantly by this mesoscale variability. This mesoscale variability is usually subgrid in numerical models and therefore must be parameterized. The source of the mesoscale moisture variability appears to be related to a cold front. Mesoscale flux divergence is explicitly included into the budget of sensible heat and moisture. The average vertical mesoscale flux divergence is small compared to the turbulent flux for the two cases investigated. However, the vertical mesoscale flux can be large locally. The budgets indicate the importance of horizontal advection for the NOPEX region. The time evolution of sensible heat and moisture during 14 June appears to be dominated by large scale horizontal advection. A comparison between the area-averaged surface flux from aircraft data and surface flux stations for the 13 June is not conclusive because of fractional cloud cover. For the strong wind Case on 14 June, the surface fluxes obtained from aircraft data and from surface flux stations disagree, which appears to be related with the pronounced mesoscale moisture variability.The regional surface fluxes of sensible heat and moisture were estimated for two days during Nopex '94 by aircraft measurements. A box flight pattern was analyzed for 13 June for weak wind case and 14 June for strong wind case, both with cold air advection. A scale analysis was performed to identify the main transporting scales of the turbulent fluxes and to study the mesoscale variability of the sensible heat and moisture flux. Analysis indicates the importance of horizontal advection for the Nopex region. The time evolution of sensible heat and moisture during 14 June was dominated by a large scale horizontal advection."
"7004770051;7006006259;","Tephra event stratigraphy and emplacement of volcaniclastic sediments, Mogan and Fataga stratigraphic intervals, part II: Origin and emplacement of volcaniclastic layers",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032455123&partnerID=40&md5=dadca10331017b53c22090bfe210cd78","We subdivided volcaniclastic layers drilled during Leg 157 around Gran Canaria at distances up to 70 km from the shore of the island at Hole 953C, 955A, and 956B deposited between 14 and ~11.5 Ma into >100 volcaniclastic units at each site. Most volcaniclastic layers are <20 cm thick, but complex turbidite units up to 1.5 m thick make up 10% to 20% of all volcaniclastic units in Holes 953C and 956B. We distinguish several types of clasts: felsic vitroclasts, (1) bubble-wall/junction shards, (2) brown nonvesicular felsic shards, (3) welded tuff clasts, (4) pumice shards, and (5) sideromelane shards. Mineral phases comprise anorthoclase and lesser amounts of plagioclase, calcic and sodic amphibole (kaersutite, richterite, and edenite), clinopyroxene (titanaugite to aegirine), hypersthene, minor enstatite, phlogopite, Fe/Ti oxides, sphene, chevkinite, apatite, and zircon. Xenocrysts are dominantly titanaugite derived from the subaerial and submarine shield basalts. Lithoclasts are mainly tachylitic and crystalline basalt, the latter most common in Hole 953C, and fragments of felsic lava and ignimbrite. Bioclasts consist of open planktonic foraminifers and nannofossil ooze in the highly vitric layers, while filled planktonic foraminifers, benthic foraminifers, and a variety of shallow water calcareous and siliceous fossils and littoral skeletal debris are common in the basal coarser grained parts of turbidites. Volcaniclastic sedimentation during the time interval 14-9 Ma was governed dominantly by direct and indirect volcanic processes rather than by climate and erosion. Most volcaniclastic units thought to represent ignimbrite eruptions consist of a coarse basal part in which pumice and large brown nonvesicular and welded tuff shards and crystals dominate, and an upper part that commonly consists of thin turbidites highly enriched in bubble-wall shards. The prominent coarser grained and vitroclast-rich volcaniclastic layers were probably emplaced dominantly by turbidity currents immediately following entry of ash flows into the sea. The brown, blocky and splintery, dense, completely welded, dominantly angular to subrounded, partially to completely welded tuff shards are thought to have formed by quench fragmentation (thermal shock) as the hot pyroclastic flows entered the sea, fragmentation of cooling ignimbrite sheets forming cliffs along the shore, and water vapor explosions in shallow water. Well-sorted beds dominated by bubble-wall/junction shards may have formed by significant sorting processes during turbidite transport into the deep (300-4000 m) marine basins north and south of Gran Canaria. Some may also have been generated largely by grinding of pumice rafts and fallout and/or by interface-shearing of coignimbrite ash clouds traveling over the water surface. Generally fresh sideromelane shards that occur dispersed in many felsic volcaniclastic layers and in one hyaloclastite layer are mostly nonvesicular and blocky. They indicate submarine basaltic eruptions at water depths of several hundred meters on the slope of Gran Canaria synchronously with felsic ash flow eruptions on land."
"7004301502;7202162685;","Characteristics of small tropical cumulus clouds and their impact on the environment",1998,"10.1029/98JD02579","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033610825&doi=10.1029%2f98JD02579&partnerID=40&md5=45aee5b9e25a08c526cceae6fc1fc016","This study uses a number of data sets (Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator data, space shuttle photography, Radiation Measurement System data, aircraft data, and shipboard soundings) to investigate the characteristics of small tropical cumulus clouds and their impact on their environment. The goal is to uncover useful information with application to radiative transfer simulation and satellite remote sensing. In fields of small cumulus clouds, size distributions are found to decrease in number with increasing diameter according to a double power law relation, often with a clear break diameter. Fractal dimensions corresponding to the horizontal area and perimeter of the clouds are greater for the larger clouds than for the smaller clouds, with the same break diameter as the size distributions, meaning that the larger clouds have more ragged perimeters. These two results suggest a characteristic horizontal length scale dividing larger and smaller boundary layer cumuli. Spatial distributions show a clear tendency toward clustering. Smaller cumuli appear to grow upward more quickly with increasing horizontal size than do larger cumuli. Albedo is found to increase with greater cloud fraction and higher solar zenith angle. Even sparse fields of small cumulus cause significant shortwave forcing at the ocean surface. Simulation suggests that small cumulus may introduce significant errors into sea surface temperature retrievals and that such clouds can be difficult to remove with operational cloud-filtering schemes. Clouds smaller than about 1 km in diameter are not seen to precipitate. Copyright 1998 by the American Geophysical Union."
"7102636922;7006812924;57212856885;","Snow-albedo feedback and the spring transition in a regional climate system model: Influence of land surface model",1998,"10.1029/98JD00790","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033610925&doi=10.1029%2f98JD00790&partnerID=40&md5=aa242eda1d6fb30ef838080c92421a2a","Using the Arctic regional climate system model (ARCSYM), we investigate the spring seasonal transition and mechanisms controlling snowmelt over a domain covering the northern half of Alaska. Annual simulations for 1992 comparing the Biosphere-Atmosphere Transfer Scheme (BATS) and the land surface model scheme (LSM) show that the BATS experiment enters the spring transition with respect to the large-scale atmospheric regime approximately one month earlier than observed climate and the LSM experiment transitions a month later than observed, even though the air temperature in the LSM experiment is generally warmer than in the BATS experiment. A more detailed examination reveals that each simulation commences and completes the snowmelt period at about the same time but that the LSM snowmelt is more rapid than in the BATS experiment. Controlling the snowmelt is the initial snowpack depth and the surface energy budget, both of which involve a complex series of feedbacks between shortwave and longwave radiation, cloud, surface turbulent fluxes, and vegetation. The snowmelt over tundra regions dominates the more rapid snowmelt seen in the LSM simulation. It is determined that the most crucial differences between the BATS and the LSM schemes are the partitioning of net ground heat flux between patches of snow and bare ground and the formulation of snow albedo. Copyright 1998 by the American Geophysical Union."
"6603680545;6601990890;7103232081;7103377710;","A two-dimensional model with input parameters from a general circulation model: Ozone sensitivity to different formulations for the longitudinal temperature variation",1998,"10.1029/98JD02354","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17944398378&doi=10.1029%2f98JD02354&partnerID=40&md5=3ca60045e953134df53258f8540739fc","Net heating and temperature derived from the middle atmospheric version of the National Center for Atmospheric Research's Community Climate Model (MA CCM2) history tapes are used to evaluate three different approaches to account for zonal temperature asymmetries in the calculation of gas phase and heterogeneous chemical reaction rate constants and polar stratospheric cloud (PSC) surface area in a two-dimensional chemistry transport model (2-D CTM). The first method uses the daily (and monthly) averaged three-dimensional (3-D) temperature distribution derived from the MA CCM2 to calculate chemical and heterogeneous reaction rates at each 3-D grid point, followed by zonal averaging (pseudo-3-D method). The second method uses 3-D daily temperature statistics from the MA CCM2 to calculate the monthly averaged probability function (stochastic approach). The third method is based on a planetary wave superposition on the zonally averaged temperature (wave approach). The sensitivity of the gas phase reactions to the longitudinal temperature asymmetry is small, while the sensitivity of the heterogeneous reaction rates is comparable to the ozone response to aircraft emissions. All three methods of accounting for longitude temperature asymmetry give similar PSC morphologies in the southern hemisphere, in good agreement with climatological data and independent model calculations. In the northern hemisphere, where the CCM2 winter temperatures at high latitudes are known to be warmer than those observed, the PSCs predicted by the pseudo-3-D and wave methods are much scarcer than those observed or calculated by other authors using climatological temperatures. For the same reason, all other methods employed in the present study failed to predict any PSCs in the northern hemisphere. Copyright 1998 by the American Geophysical Union."
"6701401890;57214539790;","A 3-D coupled ice-ocean model applied to Hudson Bay, Canada: The seasonal cycle and time-dependent climate response to atmospheric forcing and runoff",1998,"10.1029/98JC02066","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032534201&doi=10.1029%2f98JC02066&partnerID=40&md5=de9b0f7f94153a84be376c75c56de363","A coupled three-dimensional, time-dependent ice-ocean model is developed and applied in order to reproduce the basin-scale ice and mixed-layer physical properties of Hudson Bay and James Bay, Canada. Models for albedo, evaporation, storms, frazil ice production, and radiation are included. Observed monthly means of winds, temperature, precipitation, runoff, and cloudiness are used to force the model and obtain multiyear, steady state, and non-steady state solutions. The seasonal cycle in sea ice thickness, ice concentration, ocean temperature, and salinity is first reproduced. Then we consider a set of five experiments: (1) a strong westerly event from the North Atlantic Oscillation, (2) a year with anomalously high runoff, (3) regulated runoff from hydroelectric development, (4) high autumn winds, and (5) warm conditions. We find that preconditioning of the ocean for winter, controlled by the heat transfer to the atmosphere and freshwater input rates and also related to the mixed-layer depth attained before freezing, has a strong control over the following ice season. The results show that varying runoff has more of an effect on sea-ice production in southeastern Hudson Bay than do temperature changes associated with the North Atlantic Oscillation but that both have a small effect on the ice cover when compared to the observed interannual variability. Regulated runoff produces a positive sea-ice anomaly during the January-April period which is significant (greater than 10 cm or 10%) in the southeastern part of the bay but less than 1 cm (1%) on average. We conclude that 90% of the excess winter runoff remains liquid. No significant delay is computed for breakup dates (less than 3 days in southeastern Hudson Bay and less than 1 day overall). Other controls from the atmosphere are required to explain the natural interannual variability of the ice cover. Summer and autumn winds, and air temperature (which control heat loss and winter preconditioning), spring cloud cover (which controls heat gain), and snow cover (which controls the winter insulation) can explain relatively large changes in the system. Simple climate warming by 2C produces large impacts in the ice-ocean system, reducing the winter ice volume by over 20%. © 1998 by the American Geophysical Union."
"57193882808;","Toward cloud resolving modeling of large-scale tropical circulations: A simple cloud microphysics parameterization",1998,"10.1175/1520-0469(1998)055<3283:TCRMOL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033232464&doi=10.1175%2f1520-0469%281998%29055%3c3283%3aTCRMOL%3e2.0.CO%3b2&partnerID=40&md5=4a72dba4eb71dd1abd8c3df76c9ef780","This paper discusses cloud microphysical essential for large-scale tropical circulation and the tropical climate, as well as the strategy to include them in large-scale modelsi that resolve cloud dynamics. The emphasis is on the ice microphysics, which traditional cloud models consider in a fair complex manner and where a simplified approach is desirable. An extension of the classical warm rain bulk parameterization is presented. The proposed scheme retains simplicity of the warm rain parameterization (e.g., only two classes of condensed water are considered) but introduces two important modifications for temperatures well below freezing: 1) the saturation conditions are prescribed based on saturation with respect to ice, not water; and 2) growth characteristics and terminal velocities of precipition particles are representative for ice particle, not raindrops. Numerical tests suggest that, despite its simplicity, the parametrization is able to capture essential aspects of the cloud microphsics important for the interaction between convection and large-scale evironment. As an example of the application of this parameterization, preliminary results of the two-dimensional cloud-resoulving simulation of a Walker-like circulation are presented."
"6602178158;7403931916;","Average ice crystal size and bulk short-wave single-scattering properties of cirrus clouds",1998,"10.1016/S0169-8095(98)00083-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032216257&doi=10.1016%2fS0169-8095%2898%2900083-0&partnerID=40&md5=1bfe3a6642260c311fbfb696a32348a5","The bulk single-scattering properties of cirrus clouds required for driving the radiation scheme in large-scale climate models are computed with respect to various size distributions and ice crystal shapes. It is shown that the average ice crystal size, defined as the ratio of total volume to the total projected area, can well-characterize the effect of various size distributions in determining the bulk radiative properties of cirrus clouds. Details of the size distributions are not significant in specifying the radiative properties of these clouds if the effective average size is thus defined. Therefore, the ratio of the total volume to the total projected area is an ideal parameter for describing the bulk single-scattering properties. The effect of ice crystal shape is not critical in the parameterization of the extinction coefficient and single-scattering albedo. However, the various crystal habits must be accounted for in the parameterization of the asymmetry parameter. The resulting parameterization is intended for radiative transfer calculations in volving cirrus clouds in large-scale models."
"57193882808;57203012011;7006095466;56216811200;","Cloud-resolving modeling of cloud systems during phase III of GATE. Part II: Effects of resolution and the third spatial dimension",1998,"10.1175/1520-0469(1998)055<3264:CRMOCS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033232461&doi=10.1175%2f1520-0469%281998%29055%3c3264%3aCRMOCS%3e2.0.CO%3b2&partnerID=40&md5=13e9dc279fc90f6c4f5fad71cbae51a7","Two- and three-dimensional simulations of cloud systems for the period of 1-7 September 1974 in phase III of the Global Atmospheric Research Programme (GARP) Atlantic Tropical Experiment (GATE) are performed using the approach discussed in Part I of this paper. The aim is to reproduce cloud systems over the GATE B-scale sounding array. Comparison is presented between three experiments driven by the same large-scale conditions: (i) a fully three-dimensional experiment, (ii) a two-dimensional experiment that is an east-west section of the three-dimensional case, and (iii) a high-resolution version of the two-dimensional experiment Differences between two- and three-dimensional frameworks and those related to spatial resolution are analyzed. The three-dimensional experiment produced a qualitatively realistic organization of convection: nonsquall clusters, a squall line, and scattered convection and transitions between regimes were simulated. The two-dimensional experiments produced convective organization similar to that discussed in Part I. The thermodynamic fields evolved very similarly in all three experiments, although differences between model fields and observations did occur. When averaged over a few hours, surface sensible and latent heat fluxes and surface precipitation evolved very similarly in all three experiments and evaluated well against observations. Model resolution had some effect on the upper-troposheric cloud cover and consequently on the upper-tropospheric temperature ten-dency due to radiative flux divergence. When compared with the fully three-dimensional results, the two-dimensional simulations produced a much higher temporal variability of domain-averaged quantities The results support the notion that, as long as high-frequency temporal variability is not of primary importance, low-resolution two-dimensional simulations can be used as realizations of tropical cloud systems in the climate problem and for improving and/or testing cloud parameterizations for large-scale models."
"7006033481;","Far reach of the Tenth century Eldgja eruption, Iceland",1998,"10.1023/A:1005323724072","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031667473&doi=10.1023%2fA%3a1005323724072&partnerID=40&md5=00c7f1325e4511b0e062becda0ef9e26","At the end of Iceland's settlement period in the 10th century, a great basalt fissure eruption known as Eldgja (Fire Chasm) occurred near the southern settlements and destroyed a portion of them. This lava outpouring was one of the two largest terrestrial fissure eruptions of the last 11 centuries. Historical documents from Iceland, western Europe, and the Middle East are used to trace the eruption's possible climatic and demographic consequences. The cloud of aerosols from the eruption, traversing northern Europe, dimmed and reddened the Sun. There followed a very cold winter, famine, and a widespread disease epidemic during the next year and, again, 5 to 7 years after the eruption, probably as a result of the long-lived stratospheric aerosol veil. Convergent lines of evidence point to 934 as the year of the eruption. Accordingly, it becomes possible to date within a year a prominent acid horizon in ice laid down in central Greenland and, tentatively, to interpret some critical events and dates in early Icelandic history."
"7004605273;7004198955;","Changes in sunshine duration are correlated with changes in daily temperature range this century: an analysis of Swiss climatological data",1998,"10.1029/98GL02810","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032193993&doi=10.1029%2f98GL02810&partnerID=40&md5=56d7b8c426191c98943c12820d3cc419","Analyses of the relationship between trends in daily temperature range and those of sunshine duration in the Swiss Alps show a strong correlation at lower elevation sites. The decrease in daily temperature range is associated with a corresponding decrease in sunshine duration. At high elevations, however, this relationship is absent. The decrease in daily temperature range observed this century at lower elevation sites is inferred to be a consequence of an increase in low-level cloudiness. Higher elevation sites lie above the low-level cloud layers and the moisture-laden lower atmospheric boundary layer and as a result do not exhibit the same trends.Analyses of the relationship between trends in daily temperature range and those of sunshine duration in the Swiss Alps show a strong correlation at lower elevation sites. The decrease in daily temperature range is associated with a corresponding decrease in sunshine duration. At high elevations, however, this relationship is absent. The decrease in daily temperature range observed this century at lower elevation sites is inferred to be a consequence of an increase in low-level cloudiness. Higher elevation sites lie above the low-level cloud layers and the moisture-laden lower atmospheric boundary layer and as a result do not exhibit the same trends."
"7004173561;6505947778;55207447000;6701758551;7103371591;13310224800;35395776600;","Models overestimate diffuse clear-sky surface irradiance: A case for excess atmospheric absorption",1998,"10.1029/98GL52809","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032193694&doi=10.1029%2f98GL52809&partnerID=40&md5=49482d46f6d9af78f414d2e0c536250e","Radiative transfer models consistently overestimate surface diffuse downward irradiance in cloud-free atmospheres by 9 to 40% at two low altitude sites while correctly calculating direct-normal Solar irradiance. For known systematic and random measurement errors and for realistic aerosol optical properties, the discrepancy can be resolved by a reduction in the vertical aerosol optical thickness (AOT) inferred from sunphotometric measurements by an average 0.02 ± 0.01 for 32 cases examined, together with a compensating increase in a continuum-like atmospheric absorptance over the solar spectrum of ~5.0% ± 3.0%. This phenomenon is absent at two high altitude sites, where models and measurements agree to within their mutual uncertainties. Examination of apparent AOT at several locations around the globe also indicates presence of such excess atmospheric absorption. The proposed absorption and corresponding reduction in AOT would have important consequences for climate prediction and remote sensing. Copyright 1998 by the American Geophysical Union."
"7005310521;13806362800;","Polar stratospheric clouds: a high latitude warming mechanism in an ancient greenhouse world",1998,"10.1029/98GL02492","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032531360&doi=10.1029%2f98GL02492&partnerID=40&md5=08555e06dd2a0cc80941118b133243a1","The presence of water vapor clouds in the stratosphere produces warming in excess of tropospheric greenhouse warming, via radiative warming in the lower stratosphere. The stratospheric clouds form only in regions of very low temperature and so the warming produced by the clouds is concentrated in polar winter regions. Results from a paleoclimate modeling study that includes idealized, prescribed polar stratospheric clouds (PSCs) show that the clouds cause up to 20°C of warming at high latitude surfaces of the winter hemisphere, with greatest impact in oceanic regions where sea ice is reduced. The modeled temperature response suggests that PSCs may have been a significant climate forcing factor for past time intervals associated with high concentrations of atmopsheric methane. The clouds and associated warming may help to explain long-standing discrepancies between model-produced paleotemperatures and geologic proxy temperature interpreations at high latitudes, a persistent problem in studies of ancient greenhouse climates.The presence of water vapor clouds in the stratosphere produces warming in excess of tropospheric greenhouse warming, via radiative warming in the lower stratosphere. The stratospheric clouds form only in regions of very low temperature and so the warming produced by the clouds is concentrated in polar winter regions. Results from a paleoclimate modeling study that includes idealized, prescribed polar stratospheric clouds (PSCs) show that the clouds cause up to 20 °C of warming at high latitude surfaces of the winter hemisphere, with greatest impact in oceanic regions where sea ice is reduced. The modeled temperature response suggests that PSCs may have been a significant climate forcing factor for past time intervals associated with high concentrations of atmospheric methane. The clouds and associated warming may help to explain long-standing discrepancies between model-produced paleotemperatures and geologic proxy temperature interpretations at high latitudes, a persistent problem in studies of ancient greenhouse climates."
"6602130112;13406672500;","3D radiative transfer in weakly inhomogeneous medium. Part I: Diffusive approximation",1998,"10.1175/1520-0469(1998)055<2946:RTIWIM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032455020&doi=10.1175%2f1520-0469%281998%29055%3c2946%3aRTIWIM%3e2.0.CO%3b2&partnerID=40&md5=c01daea2cff5f2af7f7f961bce9396bb","The solution of the three-dimensional radiative transfer equation in weakly horizontally inhomogeneous medium has been obtained in the diffusion approximation using the expansion of the three-dimensional deltaEddington approximation. The solution approach, referred as the gradient correction (GC) method, expands the horizontal fluxes and the source function in terms of the horizontal gradient of the extinction coefficient and/ or the cloud-top boundary. In the transfer equation, only the zeroth- and first-order gradient retained and hence the following limitations apply. First, the length of the horizontal variations of optical properties of the medium should be large in comparison to the mean radiative transport length. Second, the radio of the vertical to horizontal scales should be small enough to that fluxes from boundaries may be neglected. Since there are no restrictions to the amplitude the optical properties variations, this method may even be applicable to a medium with strong horizontal variations of optical properties, as long as scales of the variations are large enough in camparison to the radiative transport length. The analytical solutions are in excellent agreement with the more accurate numerical solutions. The solutions also shows the solar zenith angle dependence of the albedo, similar to that observed in analyses of satellite imagery. The GC approach may be useful as a fast and computationally inexpenseve method both for the correction of the independent pixel approximation used for extraction of cloud fields from satellite imagery and possibly for the calculation of the radiation fluxes in climate models."
"57203012011;57193882808;6504606508;","Long-term behavior of cloud systems in TOGA COARE and their interactions with radiative and surface processes. Part I: Two-dimensional modeling study",1998,"10.1175/1520-0469(1998)055<2693:LTBOCS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032455283&doi=10.1175%2f1520-0469%281998%29055%3c2693%3aLTBOCS%3e2.0.CO%3b2&partnerID=40&md5=b1103c1ec349ec0ce8b31e4135a04398","Two-dimensional cloud-resolving modeling of tropical cloud systems was performed for a 39-day pariod (5 December 1992 through 12 January 1993) during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE). This period contains strong convective episodes within a major westerly wind burst. A cloud-resolving model combined with a cloud-interactive radiation scheme was driven by the observed evolving large-scale forcing for temperature and moisture, evolving large-scale horizontal winds, and evolving sea surface temperature. These all represent averaged conditions over the Intensive Flux Array of TOGA COARE. Model-produced quantities were evaluated against the observational data and used to quantify interactions of the simulated cloud systems with radiative and surface processes. Focus is on quantities of value to cloud-climate research and to an improved physical basis for the parameterization of cloud systems per se. During convectively disturbed periods (strong forcing), the collective effects of cloud systems on the thermodynamic fields and budgets, radiative fluxes, surface heat fluxes, and surface energy budgets are well simulated. However, during relatively undisturbed periods (weak forcing), the comparison between model-produced quantities and observations is less satisfactory. Specifically, the domain-averaged temperature and moisture fields of the model are too warm and too moist, and the domain-averaged outgoing longwave radiative flux is too small. The absence of observed data to specify large-scale forcing for the condensed water, which is required by the use of periodic lateral boundary conditions, is argued to be one of the reasons why the cloud (ice and liquid) water content is too large. The role of cloud systems and oceanic processes in the regulation of the sea surface temperature over the tropical oceans is also discussed."
"7404325680;7004890737;24369480200;57209062233;6507903801;","The GMS Pathfinder Project",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032165789&partnerID=40&md5=76d346ef38c00ba400680c8071291169","A collaborative Geostationary Meteorological Satellite (GMS) Pathfinder Project involving the Australian Bureau of Meteorology (ABM), the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the Scripps Institution of Oceanography (SIO) and the United States National Aeronautics and Space Administration (NASA), with cooperation from the Japan Meteorological Agency (JMA), is underway. Selected data from Japan's Geostationary Meteorological Satellite (GMS-5) during a benchmark period (1 July 1995 - 30 June 1996) are being examined as part of this activity. The objective of the project is to provide a high-quality dataset suitable for climate analysis and research. Sources of noise in the data will be minimised, accurate cloud-detection algorithms will be developed, and accurate navigation and radiometric calibration will be appended to the data. To demonstrate the scientific usefulness of the GMS Pathfinder data for analysis and climate research, we will examine satellite-observed and derived variables which may be useful to monitor oceanic and land-surface changes that occurred over the Australian continent and its surrounding seas during the benchmark period. The datasets and documentation developed as part of this project will be made available to NASA's designated Distributed Active Archive Center (DAAC) and to a designated Australian site. These data and documentation also will be fully available to the scientific community for research purposes."
"6602873453;57210717445;35592560600;","Radiative forcing of climate by sulfate aerosols as determined by a regional circulation chemistry transport model",1998,"10.1016/S1352-2310(98)00028-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032537884&doi=10.1016%2fS1352-2310%2898%2900028-4&partnerID=40&md5=d36f80c6cbc3429816edf8dc5471706e","H2SO4/SO42- aerosols have the potential to modify the radiation budget of the atmosphere. Under clear-sky condition they scatter solar radiation back to space, reducing absorption of solar irradiance (direct effect). The capability of sulfate particles to act as cloud condensation nuclei, thus influencing cloud droplet number concentration, cloud albedo and the development of precipitation is referred to as indirect effect. Evidence has been presented that sulfate aerosol climate forcing is sufficiently large to reduce significantly the positive forcing by anthropogenic greenhouse gases regionally, especially in the Northern Hemisphere. Until now, only coarse grid global models with rather simple chemistry modules have been applied to estimate the radiative forcing of sulfate aerosols. In this paper we would like to ascertain the short wave sulfate forcing over Europe, one of the main anthropogenic source regions. For this purpose the three-dimensional European sulfate distribution was generated by a regional climate model in combination with a complex chemistry transport model. Then a computationally efficient radiation transfer model was applied. It estimates the direct and indirect short wave forcing of sulfate aerosols on the basis of the variable sulfate mass distribution and meteorological input data. For comparison coarse grid global model results will be shown. Regional and global model results are comparable concerning the distribution and amount of sulfate burden and radiative forcing over Europe. Hence, for the estimation of the European budgets, the global model produces sufficiently precise information. As expected, the advantage of the higher resolution regional model is to show smaller scale phenomena, which cannot be resolved by the global model. Different predictions of the amount of clouds by the regional and global model modify the forcing significantly, emphazising the role of clouds in estimating the direct (and, of course, the indirect) short wave forcing of sulfate aerosols. It is further interesting to note that in the global model results about 30% of the sulfate burden and its short wave radiative forcing over Europe, one of the main anthropogenic source regions, is caused by sulfate from natural sources (DMS and volcanoes). Thus, the long-range transport of primary and secondary pollutants from outside the regional model domain contributes significantly to the limited area model's atmospheric load. Therefore, the initial and boundary chemical composition of the atmosphere for the limited area model should be investigated in more detail in the future."
"35446498700;7405728922;","Searching for a regional fingerprint of aerosol radiative forcing in the southeastern US",1998,"10.1029/98GL02106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032148204&doi=10.1029%2f98GL02106&partnerID=40&md5=d4f93626055c05a61a0faa90535e3632","Although aerosols have long been considered to exert a cooling influence on the regional climate due to direct and indirect radiative forcing, persuasive evidence of the response to this forcing has been lacking. Here, we analyze the regional patterns of climate change in the Southeast US during the period 1949-94 to search for a fingerprint of aerosol radiative forcing. The results show that direct and indirect radiative forcing of both natural (such as Pinatubo volcanic aerosols) and anthropogenic aerosols (such as those transported from the polluted regions of US) may be responsible for the regional cooling trend in the Southeast during the past 46 years. Lack of availability of long term measurements precludes a rigorous cause-and-effect analysis. Circumstantial evidence presented here imply justifies immediate establishment of a network of measurements of aerosol optical depth and cloud reflectivity in the southeastern US.Although aerosols have long been considered to exert a cooling influence on the regional climate due to direct and indirect radiative forcing, persuasive evidence of the response to this forcing has been lacking. Here, we analyze the regional patterns of climate change in the Southeast US during the period 1949-94 to search for a fingerprint of aerosol radiative forcing. The results show that direct and indirect radiative forcing of both natural (such as Pinatubo volcanic aerosols) and anthropogenic aerosols (such as those transported from the polluted regions of US) may be responsible for the regional cooling trend in the Southeast during the past 46 years. Lack of availability of long term measurements precludes a rigorous cause-and-effect analysis. Circumstantial evidence presented here amply justifies immediate establishment of a network of measurements of aerosol optical depth and cloud reflectivity in the southeastern US."
"7006033615;7005413462;","Seasonal and regional responses to changes in Australian soil moisture conditions",1998,"10.1002/(SICI)1097-0088(199808)18:10<1105::AID-JOC308>3.0.CO;2-G","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032446368&doi=10.1002%2f%28SICI%291097-0088%28199808%2918%3a10%3c1105%3a%3aAID-JOC308%3e3.0.CO%3b2-G&partnerID=40&md5=ec30c2ddd17e3d2b0b25908a4a54f49c","This paper addresses the interaction of large scale soil moisture anomalies and the atmospheric circulation. This approach is based on a suite of GCM experiments in which the soil was instantaneously saturated and desiccated over the entire Australian continent. These conditions were imposed on the first day of each of the 12 calendar months and anomaly simulations integrated for 4 months. The 'memory' of these changes as reflected in the important climate elements was analysed. The subsequent anomalies of soil moisture exhibited the greatest persistence of up to and beyond 4 months. This persistence was most apparent for the simulations initiated in winter. The surface latent heat anomalies showed comparable, if slightly smaller, levels of persistence. Somewhat smaller amounts of perseverance were found for the anomalies of surface air temperature, even less in the precipitation (and indeed none in the desiccated case), and very modest amounts in the mean sea level pressure. The results shown here demonstrate substantial symmetry in the transient response to the climate system to these wet and dry soil moisture conditions. Also apparent to a seasonal and regional dependence in the way in which the model recovers from the perturbations to the moisture. These three characteristics are seen to be connected to some extent. The explanation for the behaviours lies in the many nonlinear processes in the land-atmosphere system and the complex roles played by convection, cloud, circulation regimes (including the monsoon), thermal conditions, and horizontal moisture transports."
"6603706537;7006371623;","Trends in total rainfall, heavy rain events and number of dry days in Australia, 1910-1990",1998,"10.1002/(SICI)1097-0088(199808)18:10<1141::AID-JOC286>3.0.CO;2-P","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032431315&doi=10.1002%2f%28SICI%291097-0088%28199808%2918%3a10%3c1141%3a%3aAID-JOC286%3e3.0.CO%3b2-P&partnerID=40&md5=2ad43f9d1e0654b49a3abc53d707b317","Trends in heavy rainfall, total rainfall and number of dry days in Australia have been analysed using daily rainfall records in 125 stations. Summer and winter halves of the year were considered separately for the period 1910-1990. The summer half-year is defined as November-April, while the winter-half is May-October. Heavy rainfall is defined as the 90th and 95th percentiles of daily rainfall in each half year. The magnitude of trends was derived from linear regression while statistical significance was determined by Kendall-Tau and field significance tests. Increasing trends in heavy rainfall and total rainfall have occurred during the summer half-year, but only 10-20% of stations have statistically significant trends. During the winter half-year, heavy rainfall and total rainfall have also increased, except in far southwest Western Australia and inland Queensland. There has been a reduction in the number of dry days in both halves of the year, except in far southwest Western Australia and at a few stations in eastern Australia where there has been an increase in the number of dry days in the winter half-year. Changes in the number of dry days were statistically significant at over 50 of stations. Hence there are regions showing coherent increases and decreases in rainfall which may be due to systematic changes in climate during the last century. Trends were averaged over three broad regions with adequate station coverage. There has been a general decrease in dry days with an increase in total and heavy rainfall intensity in the northeast and southeast, and a decrease in total and heavy rainfall in the southwest. These rainfall changes are related to changes in other climate variables such as temperature and cloud over in Australia."
"7201432984;7006839912;7202429440;7005254328;7006399419;7006424590;35465220500;6701425363;7005022197;","Processes controlling the distribution of aerosol particles in the lower marine boundary layer during the first aerosol characterization experiment (ACE 1)",1998,"10.1029/97JD03720","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1542573399&doi=10.1029%2f97JD03720&partnerID=40&md5=960092f74e7b70f54bc3d585d9aed81d","The goals of the International Global Atmospheric Chemistry (IGAC) Program's First Aerosol Characterization Experiment (ACE 1) are to determine and understand the properties and controlling factors of the aerosol in the remote marine atmosphere that are relevant to radiative forcing and climate. A key question in terms of this goal and the overall biogeochemical sulfur cycle is what factors control the formation, growth, and evolution of particles in the marine boundary layer (MBL). To address this question, simultaneous measurements of dimethylsulfide (DMS), sulfur dioxide (SO2), the aerosol chemical mass size distribution, and the aerosol number size distribution from 5 to 10,000 nm diameter were made on the National Oceanic and Atmospheric Administration (NOAA) ship Discoverer. From these data we conclude that the background MBL aerosol during ACE 1 often was composed of four distinct modes: An ultrafine (UF) mode (Dp = 5-20 nm), an Aitken mode (Dp = 20-80 nm), an accumulation mode (Dp = 80-300 nm), and a coarse mode (Dp &gt; 300 nm). The presence of UF mode particles in the MBL could be explained by convective mixing between the free troposphere (FT) and the MBL associated with cloud pumping and subsidence following cold frontal passages. There was no evidence of major new particle production in the MBL. Oceanic emissions of DMS appeared to contribute to the growth of Aitken and accumulation mode particles. Coarse mode particles were comprised primarily of sea salt. Although these particles result from turbulence at the air-sea interface, the instantaneous wind speed accounted for only one third of the variance in the coarse mode number concentration in this region. © Copyright 1998 by the American Geophysical Union."
"7201432984;7006839912;7202429440;7005254328;7006399419;7006424590;35465220500;6701425363;7005022197;","Processes controlling the distribution of aerosol particles in the lower marine boundary layer during the First Aerosol Characterization Experiment (ACE 1)",1998,"10.1029/97JD03720","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032551823&doi=10.1029%2f97JD03720&partnerID=40&md5=17d50e803d23a80d9e6dafc5ca49607d","The goals of the International Global Atmospheric Chemistry (IGAC) Program's First Aerosol Characterization Experiment (ACE 1) are to determine and understand the properties and controlling factors of the aerosol in the remote marine atmosphere that are relevant to radiative forcing and climate. A key question in terms of this goal and the overall biogeochemical sulfur cycle is what factors control the formation, growth, and evolution of particles in the marine boundary layer (MBL). To address this question, simultaneous measurements of dimethylsulfide (DMS), sulfur dioxide (SO2), the aerosol chemical mass size distribution, and the aerosol number size distribution from 5 to 10,000 nm diameter were made on the National Oceanic and Atmospheric Administration (NOAA) ship Discoverer. From these data we conclude that the background MBL aerosol during ACE 1 often was composed of four distinct modes: an ultrafine (UF) mode (Dp = 5-20 nm), an Aitken mode (Dp = 20-80 nm), an accumulation mode (Dp = 80-300 nm), and a coarse mode (Dp &gt; 300 nm). The presence of UF mode particles in the MBL could be explained by convective mixing between the free troposphere (FT) and the MBL associated with cloud pumping and subsidence following cold frontal passages. There was no evidence of major new particle production in the MBL. Oceanic emissions of DMS appeared to contribute to the growth of Aitken and accumulation mode particles. Coarse mode particles were comprised primarily of sea salt. Although these particles result from turbulence at the air-sea interface, the instantaneous wind speed accounted for only one third of the variance in the coarse mode number concentration in this region. Copyright 1998 by the American Geophysical Union."
"6701530932;7005254328;","Simultaneous observations of aerosol and cloud droplet size spectra in marine stratocumulus",1998,"10.1175/1520-0469(1998)055<2180:SOOAAC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032448892&doi=10.1175%2f1520-0469%281998%29055%3c2180%3aSOOAAC%3e2.0.CO%3b2&partnerID=40&md5=a0f4753f2f99a4ccd51efd49b114a1dd","Simultaneous field measurements of aerosol and cloud droplet concentrations and droplet diameter were performed at a maritime site on the coast of Washington State. The aerosol and droplet spectra were compared for estimating cloud condensation nucleus concentration (Nccn) as the number of particles with diameters greater than 80 nm, that is, Nccn = N(Dp, &gt; 80 nm). Several analytical approaches were developed and applied to the data, including a stratification of the observations into periods of high and low liquid water content (LWC) based on a threshold value of 0.25 g m-3. The aerosol data were corrected for inertial losses of cloud droplets at the inlet using wind speed and droplet size; this correction improved the measured relationships between Nccn and droplet number concentration (Nd). These measurements, when coupled with the range of possible aerosol chemical compositions, imply a cloud supersaturation of 0.24%-0.31% at the Cheeka Peak sampling site during periods of high LWC. The observations of droplet and aerosol spectra supported Twomey's cloud brightening hypothesis in that Nccn was highly correlated (r2 = 0.8) with Nd in apparent 1:1 proportions. For the investigated range (50 cm-3 &lt; Nd &lt; 600 cm-3) droplet effective diameter (Deff) was very sensitive to variation in Nccn for 50 cm-3 &lt; Nccn &lt; 200 cm-3, somewhat sensitive for 200 cm-3 &lt; Nccn &lt; 400 cm-3, but not very sensitive to variation in aerosol number for Nccn &gt; 400 cm-3 . A model was applied to the aerosol and droplet data to predict droplet size, as Deff, from Nccn-0.33 and LWC. Predicted values for Deff agreed (r2= 0.8) with Deff determined directly from the cloud droplet spectra, suggesting that this approach should be useful in climate modeling for predicting cloud droplet size from knowledge of Nccn and LWC."
"7102953444;6602729528;","Excessive transmission of solar radiation through the cloud-free atmosphere in GCMs",1998,"10.1029/98GL51595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032525918&doi=10.1029%2f98GL51595&partnerID=40&md5=b1592f702ba83290bfe0e1c433c5667c","Large uncertainties exist in the distribution of solar radiation in the global climate system and its representation in General Circulation Models (GCMs). The present paper assesses the transmission of solar radiation through cloud-free atmospehre in three GCMs using information from direct observations at the surface. Clear-sky insolation climatologies have been constructed from hourly radiation data through composites of clear-sky episodes for seven sites in Germany with ten years of accurate measurements. The results suggest that GCMs overestimate clear-sky insolation at the surface, indicating that the cloud-free atmosphere is overly transparent to solar radiation in the models. Quantitatively, the annual mean overestimation for the German sites is on the order of 10 Wm-2 in the models which include an aerosol climatology and 30 Wm-2 in the models without aerosol. The GCM-predicted atmospheric water vapor content is abundant compared to the ECMWF Re-Analysis and therefore not considered responsible for the missing absorption in the model atmosphere. Rather, underestimated water vapor absorption in the GCM radiation codes is implied.Large uncertainties exist in the distribution of solar radiation in the global climate system and its representation in General Circulation Models (GCMs). The present paper assesses the transmission of solar radiation through cloud-free atmosphere in three GCMs using information from direct observations at the surface. Clear-sky insolation climatologies have been constructed from hourly radiation data through composites of clear-sky episodes for seven sites in Germany with ten years of accurate measurements. The results suggest that GCMs overestimate clear-sky insolation at the surface, indicating that the cloud-free atmosphere is overly transparent to solar radiation in the models. Quantitatively, the annual mean overestimation for the German sites is on the order of 10 Wm-2 in the models which include an aerosol climatology and 30 Wm-2 in the models without aerosol. The GCM-predicted atmospheric water vapor content is abundant compared to the ECMWF Re-Analysis and therefore not considered responsible for the missing absorption in the model atmosphere. Rather, underestimated water vapor absorption in the GCM radiation codes is implied."
"56233184100;6701440969;7004546654;","Rainfall-recharge relationships within a karstic terrain in the Eastern Mediterranean semi-arid region, Israel: δ18O and δD characteristics",1998,"10.1016/S0022-1694(98)00119-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032486216&doi=10.1016%2fS0022-1694%2898%2900119-X&partnerID=40&md5=d81ec0c25401bf8a73372b718f5ae861","Annual rainfall variations and processes in the upper vadose zone exert a profound influence on the chemical and isotopic compositions of waters of carbonate aquifers in semi-arid climatic zones. In order to define these processes we have studied the surface temperatures during rainfall events, the isotopic composition of rain, infiltrating and groundwaters. This study was carded out within a karstic terrain (Soreq Cave), Israel, located in Cenomanian dolomitic rocks, approximately 40 km inland of the Mediterranean Sea, and 400 m above sea level. The climate is typical of the Eastern Mediterranean semi-arid conditions, with a rainy winter and dry summer and the average annual rainfall in the area is ~500 mm. Close monitoring indicates that the δD and δ18O values of individual rainstorm events decrease with increasing rainfall. Annual average isotopic values of years with rainfall of 500-600 mm do not vary systematically. Years with extreme rainfall values define a negative covariation between the δ18O and rainfall. The δD-δ18O relationship of all rain events of more than 20 mm fall on the Mediterranean Meteoric Water Line (MMWL) with a slope of ~8 and d-excesses of 20-30‰. These rain events occur when mid-winter surface temperatures are 5 to 10°C. Rainfall events of less than 20 mm, mainly occurring at above 10°C, have slopes of less than 8 and smaller d-excess as a consequence of evaporation processes beneath the clouds. Two main water-types infiltrating into the cave are recognized: slow- and fast-drip. Slow-drip occurs from the tips of stalactites and takes place throughout the year; these waters represent seepage water that remains in the upper vadose zone for up to several decades. Fast-drip emanates from fissures in the cave roof during the winter seasons; these waters represent vadose flow with a short residence time of less than 1 year. The infiltration of the fast-drip water into the cave depends on the fracture system of the rock cover and on the intensity of the rainstorms. In the inner parts of the cave, where the rock cover is thick, fast-drip starts only after several massive (&gt;20 mm) rainstorms, whereas below a thin roof the response time of fast-drip is a few hours to a few days after intensive rainstorms. Both fast- and slow-drip water fall on the MMWL, indicating that they are derived mainly from the relatively intensive rainstorms that compose about 2/3 of the annual rainfall. Although fast-drip water represents massive rainstorms, their δ18O and δD values are nonetheless higher by ~1‰ and 10‰ respectively, relative to the average rainwater composition, This indicates that the fast-drip water consists predominantly of water derived from intensive rainstorms admixed with a minor component of isotopically 18O- and D-enriched water, which is represented by the slow-drip waters. The fast-drip waters are derived mainly from massive rain events at surface temperatures of 5 to 10°C, which thermally equilibrate with the host rock and upon reaching the cave they have already acquired the mean temperature (~20°C) of the cave.Annual rainfall variations and processes in the upper vadose zone exert a profound influence on the chemical and isotopic compositions of waters of carbonate aquifers in semi-arid regions. These processes were investigated by studying the surface temperatures during rainfall events, the isotopic composition of rain, infiltrating and groundwaters within the karstic terrain (Soreq Cave) in Israel. Close monitoring indicated that the δD and δ18O values of individual rainstorm events decrease with increasing rainfall. Two main water-types infiltrating into the cave were recognized: slow- and fast-drip. Both water types flow fall on the Mediterranean Meteoric Water Line, indicating that they are derived mainly from the relatively intensive rainstorms."
"7003561442;6701333444;13406672500;","Effects of cloud shape and water vapor distribution on solar absorption in the near infrared",1998,"10.1029/98gl01444","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032100202&doi=10.1029%2f98gl01444&partnerID=40&md5=9c2099861e042979c81c98a582925a89","A 3D Monte Carlo radiative transfer model is used to demonstrate the importance of cloud shape and water vapor distribution on narrow-band solar absorption at 0.93 and 2.0 μm. Diurnally averaged absorption for wavy-topped broken cloud fields can exceed that based on conventional climate model assumptions (plane-parallel cloud geometry and an unsaturated water vapor distribution in gaps between cloud elements) by 2-10% of the top-of-atmosphere insolation. Plane-parallel clouds often underestimate the absorption by nonflat-top clouds, particularly at 2.0 μm and large solar zenith angles. Ambiguities in assigning the above-cloud water vapor profile create uncertainties in the absorption comparisons between the plane-parallel and non-flat-top clouds, which increase with solar zenith angle and may be as large as 5 to 8%. A thin saturated water vapor layer (0.4 km) above the cloud top systematically enhances column absorption, the magnitude depends on cloud altitude and wavelength. Thus, realistic 3-D distributions of cloud shape, brokenness and water vapor are needed to quantify the role of clouds in excess absorption."
"7003869084;7004604556;7103259185;","A stochastic model of global atmospheric response to enhanced greenhouse warming with cloud feedback",1998,"10.1016/S0169-8095(98)00037-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031695543&doi=10.1016%2fS0169-8095%2898%2900037-4&partnerID=40&md5=814b2f40b6a8469ddd4202f9368718cc","An atmosphere-ocean climate box model is used to examine the influence of cloud feedback on the change in the climate system's variability in response to enhanced greenhouse warming. The model consists of three nonlinear stochastic differential equations that are simplified forms of the first law of thermodynamics for the atmosphere and ocean and the continuity equation for the atmospheric component of the hydrological cycle. The model is driven by random fluctuations in the mean evaporative flux, which is routed and distributed among the components of the system through the fluxes of energy and moisture. The model suggests that cloud feedback can lead to the occurrence of two climatic regimes into which the present climate may evolve as a result of an enhanced greenhouse warming. In the first regime, the mean values of the model parameters, such as temperature, precipitation and cloudiness, as well as the amplitude and timescale of their fluctuations, all increase moderately. In the second regime, these mean values increase substantially, and the amplitude and timescale of their fluctuations rise sharply. The model also predicts the existence of climatic hysteresis; that is, for the climate system to return from either of these regimes back to the present regime, a substantial decrease in the long-wave forcing is required."
"7409463706;7103119050;","Numerical simulations of altocumulus using a cloud resolving model and a mixed layer model",1998,"10.1016/S0169-8095(98)00034-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345726033&doi=10.1016%2fS0169-8095%2898%2900034-9&partnerID=40&md5=516259546fc33b291e10ccc24b5870d9","This paper describes the progress toward developing a parameterization of thin mid-level stratiform (altocumulus, Ac) clouds suitable for use in global climate models. 2D cloud-resolving model (CRM) simulations indicate that moist conservative variables in Ac layers are approximately well-mixed. This suggests that Ac layers may be parameterized using an elevated mixed-layer model (MLM). Therefore, an elevated MLM for Ac was developed and tested. The Ac MLM uses a method for determining the entrainment rate at the mixed layer top that is used in many MLMs of the stratocumulus-topped boundary layer (STBL). At the mixed layer base, the Ac MLM detrains at a rate that maintains a constant ratio of buoyant consumption of turbulent kinetic energy (TKE) in the subcloud layer to buoyant production in the cloud layer. To test the Ac MLM, results from it were compared to those from a CRM for a thin Ac layer and a thick Ac layer. The comparisons were good for the cloud top, cloud base, and mixed layer base heights, and fair for the liquid water path (LWP)."
"7201837768;35446498700;","Role of sulfates in regional cloud-climate interactions",1998,"10.1016/S0169-8095(98)00057-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031712838&doi=10.1016%2fS0169-8095%2898%2900057-X&partnerID=40&md5=a8013b268348759b9529cdbff18e7b8e","During the summers of 1993-1996, field experiments were conducted at Mt. Mitchell, NC, in the southeastern US. The effect of anthropogenic pollution on cloud microphysical properties such as liquid water content (ω), cloud droplet number concentration (N), effective radii (Reff), cloud condensation nuclei (CCN) activation spectrum and cloud reflectivity were investigated. Cloud water sulfate concentration was used as a measure of anthropogenic pollution. Back trajectory analysis was used to categorize the cloud forming air masses that arrived at the site. The sulfates and nitrates emission inventories of the US Environmental Protection Agency (EPA) were used to classify air masses as polluted marine (PM), polluted continental (PC) or as highly polluted (HP). Empirical values for the relationships between CCN-N, CCN-sulfate, N-sulfate and Reff-N for different air masses have been obtained. A quantitative nonlinear relationship between CCN and N was obtained. The sublinear relationship between CCN and sulfate mass indicated the susceptibility of the different air masses to the sulfate content. The lesser polluted air masses exhibited greater changes in CCN concentrations for smaller increases in sulfate mass concentrations as compared to the more polluted air masses. The relationship between Reff amd N for different air masses, as well as the N-sulfate mass relationship, suggested that the counteracting effect of sulfates on greenhouse warming for the southeastern US would be of magnitude greater than -4.0 W m-2 obtained by modeling studies. The nonlinear relationships between the cloud microphysical/optical properties and the sulfate content of the air mass implies the existence of an optimum level for the sulfate concentration beyond which cloud reflectivity stays unaffected. Analysis of 3 years of observational data established this level at 400-500 μeq l-1 of sulfate in the cloud water."
"7006131953;7006061457;","Model for an investigation of radiative transfer in cloudy atmosphere",1998,"10.1016/S0169-8095(98)00056-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031720565&doi=10.1016%2fS0169-8095%2898%2900056-8&partnerID=40&md5=aa0717eb414cfcd2443630685ef9b852","Parameterization of droplet size distributions using a composition of three gamma functions is suggested to simulate a wide spectrum of cloud droplets including drizzle and rain. It should be stressed out that this parameterization is based on extensive material (accumulated in the Russian Central Aerological Observatory) of aircraft observations in clouds and dependent on the cloud type, temperature and other factors. Effective computation technique using the geometric optics approach for the calculations of the parameters of electromagnetic scattering on spherical polydispersions and the database containing these parameters for a wide set of aerosol and cloud mediums are described. The parameterization, computation technique and the database are applied to create different optical atmospheric models with scattering properties rather close to reality for theoretical investigations of the atmospheric radiative transfer. Some examples of cloud radiation forcing studies are also considered in this paper. Their principal feature was the use of the original effective line-by-line and Monte-Carlo codes to take into account rigorously both the cloud/molecular scattering and a detailed spectral structure of water vapor, ozone, carbon dioxide and oxygen. It has been found: (a) variations of the mean droplet radius depending on the cloud temperature and other factors lead to essential changes in shortwave fluxes (tens of W/m2), cloud radiation absorption (tens of W/m2) and the Liquid Water Path (LWP) (by several times); (b) In continental clouds short wave fluxes mainly depend on small droplets. The existence of large (drizzle) drops perturbs slightly the fluxes and rather strongly affects the liquid water path and the cloud radiation absorption; (c) The solar radiation absorption and scattering by cloud media are generally defined only by the extinction coefficient and the effective radius and are slightly affected by other details of cloud size droplet distributions. These statements are in good agreement with other investigations. Thus, thesee parameterization and database should be good enough for the cloud optical properties simulation in the majority of practical applications. Moreover, the developed codes may be recommended for exact simulation of atmospheric radiative transfer in satellite and full-scale experiments, for testing and improving the radiation codes being used in climate models, etc."
"7006346740;7006163589;7004730494;6603020128;6603102974;7004600486;57205699381;6701837065;","The 1997 PMSE season - Its relation to wind, temperature and water vapour",1998,"10.1029/98gl01243","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032098330&doi=10.1029%2f98gl01243&partnerID=40&md5=81221d5719e8fff492f3a6b29797a710","Factors determining the onset and decay of the Polar Mesosphere Summer Echo (PMSE) season in 1997 are examined. PMSE from the ESRAD radar at 68° N, 20 °E are compared with simultaneous observations of stratospheric winds, upper-mesosphere temperature, upper mesosphere water vapour and noctilucent clouds. There was a 3-week delay from the start of summer, defined by temperature or stratospheric winds, to the start of PMSE. At the end of the summer, the return to winter conditions was simultaneous in all three parameters. Noctilucent clouds at 55-60° N were confined to the period of lowest temperatures, when PMSE were also present throughout the day. Water vapour observations show an increase during the summer, possibly taking place in late May, at about the time PMSE first appeared. It seems likely that the start of the PMSE season is determined by water vapour availability, while the end of the season is determined by temperature."
"7101785401;7801421469;7004227345;6603929869;7801604834;6701715507;","Australian temperature, Australian rainfall and the Southern Oscillation, 1910-1992: Coherent variability and recent changes",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032091225&partnerID=40&md5=557d2341ff5f966afadead78df59591f","The best available surface temperature (T) and precipitation (P) records for Australia dating back to 1910 have been examined to look for coherent interannual variability. P exhibits a tendency to be out of phase with daily maximum temperature, Tmax, and this results in P tending to be out of phase with both the daily average temperature, Tbar (estimated here as the average of Tmax and the daily minimum, Tmin), and the DTR (diurnal temperature range, Tmax-Tmin). The association between P and Tmin is generally weak. The (expected) increase in P associated with a positive Southern Oscillation Index is (generally) accompanied by reduced average temperatures (Tbar) and a reduced DTR, both of which primarily arise from a reduction in Tmax. When variability in both P and Tmin associated with Tmax is removed, the residual signals (P* and Tmin*) show widespread statistically significant positive correlations, consistent with the hypothesis that clouds help to reduce night-time cooling. These relationships are less clear at near-coastal sites, and absent at the island and exposed coastal sites considered. Results from three separate ten-year integrations of the Bureau of Meteorology Research Centre's atmospheric general circulation model were then examined. The tendency for (a) P to be out of phase with Tmax, Tbar and the DTR and (b) P* to be in phase with Tmin* over Australia on interannual time-scales was also generally evident over land elsewhere, except at high latitudes and over North Africa. An analysis of the model's surface heat budget over land showed that this arises from associated surface short wave radiation and latent heating anomalies. The latter is generally more important over low-latitude regions where deep convection occurs, with the hierarchy reversed elsewhere. Evaporative cooling anomalies appear to be dominated by soil moisture changes. Surface long wave radiation, sensible heating and subterranean heat exchange tend to reduce the temperature change which would otherwise occur. Recent changes in some of the relationships exhibited between observed P, T and the Southern Oscillation Index appear unusual in terms of the interdecadal variability evident in the records prior to 1972, and previous conclusions drawn on the basis of 'all-Australia' P and T indices were found to have broad applicability. Interrelationships between recent changes in the 20-year means of P, T and the SOI do not match the changes that might be expected on the basis of their interrelationship on interannual time-scales. Possible reasons for the changes suggested by the analysis (e.g., global warming and naturally occurring interdecadal climate variability) are discussed."
"35494005000;7006698304;7005807606;","Validation of hydrometeor occurrence predicted by the ECMWF Model using millimeter wave radar data",1998,"10.1029/98GL00845","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032523642&doi=10.1029%2f98GL00845&partnerID=40&md5=9520dc68407bf604270fc442964ede39","Validation of hydrometeor prediction by global models is an important issue as it pertains to the accuracy of climate predictions. In this study we use data from a continuously operating millimeter wave radar at a research site in north central Oklahoma, USA to validate output from the operational ECMWF forecast model. We demonstrate that the ECMWF model shows good overall skill at predicting the vertical distribution of the clouds and precipitation that occurred over this site during winter 1997. However, we also show that the model tended to predict the onset of deep cloud events too soon, made the layers too deep and predicted dissipation somewhat later than observed. © Copyright 1998 by the American Geophysical Union."
"6602178158;7102862273;","A possible change in cloud radiative forcing due to aircraft exhaust",1998,"10.1029/98GL51091","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032523690&doi=10.1029%2f98GL51091&partnerID=40&md5=b38e9db7aa6198f620fec454305ffeb6","Aircraft exhaust may reduce the crystal size in natural cirrus. This work investigates the change in cloud radiative forcing from such a size reduction by assuming a constant ice water content. A 1-dim model with radiative properties that depend on the mean crystal size is used to compute the radiative transfer for an atmospheric column. The results show that the negative shortwave cloud forcing is enhanced with smaller crystals as they mainly increase the reflectivity of clouds. The change in the longwave cloud forcing is always positive although its magnitude depends strongly on the ice water path. The weighted sum of SW and LW cloud forcings depends on the mean crystal size, surface albedo and ice water content. It appears that there is a range of diameters between 15 and 25 μm where the response to a reduction in crystal size is fairly insensitive. Below and above this range the change is negative or positive, respectively. In regions of dense airtraffic the magnitude of the change in cloud forcing could be on the order of 0.3 W m-2 under the assumption of a 20% decrease of the mean crystal size from about 30 μm to 24 μm. Aircraft exhaust thus has the potential to affect the climate but the results should be taken with caution as they are based on parameterized optical properties for cirrus clouds. © Copyright 1998 by the American Geophysical Union."
"6701324864;7005171879;","Cirrus cloud simulation using explicit microphysics and radiation. Part II: Microphysics, vapor and ice mass budgets, and optical and radiative properties",1998,"10.1175/1520-0469(1998)055<1822:CCSUEM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031712827&doi=10.1175%2f1520-0469%281998%29055%3c1822%3aCCSUEM%3e2.0.CO%3b2&partnerID=40&md5=de6324c8f0c3b2e2abd7cf36348350c3","The 2D/3D cloud model complex with explicit microphysics and radiation described in Part I is used to simulate the development of a midlatitude cirrus cloud, including interaction with radiation. To account for the effects of the interaction of various scales of motion on cloud development, a synoptic-scale vertical velocity field is superimposed on the mesoscale velocity field generated by the model, mimicking the effects of an upper-level shortwave trough. The main results under the conditions simulated here are the following. Cirrus cloud growth is much slower than assumed previously, because the process of vapor deposition to ice crystals is far from instantaneous: the crystal phase relaxation time (i.e., the characteristic time of vapor absorption by crystals) takes 0.5-2.0 h. Even after 1 h of cloud development, supersaturation with respect to ice can remain 5%-10%, while the condensed ice is only 40%-60% of the amount that would be realized assuming that all excess vapor is transformed into ice in typical model time steps. Although experimental and theoretical studies have produced widely divergent longwave mass absorption coefficients αmabs ranging from 100 to 3500 cm2 g-1, model results show that a single ""representative"" value of αmabs is inappropriate. Vertical profiles typically exhibit values of ∼800-1000 cm2 g-1 in the upper cloud region containing the smallest particles, in contrast to ∼100-300 cm2 g-1 for the larger crystals in the main cloud. The optical scattering coefficients behave similarly, with typical values of ∼2000-2500 cm2 g-1 in the upper cloud regions and ∼300-500 cm2 g-1 in the lower cloud regions. A strong horizontal variability is also a characteristic feature of these coefficients. Many GCM and climate models use seemingly overestimated αmabs values (e.g., 1000 cm2 g-1). Sensitivity tests show that the use of such values increases cooling in the upper cloud and heating in the lower cloud, which can lead to an unwarranted increase in upper-tropospheric static instability. The postulated effects of the positive feedbacks between clouds and greenhouse gas-induced global warming would likely be different in magnitude (or in sign) if the more realistic approach of using cloud microstructure-dependent absorption and scattering coefficients could be adopted. Consideration of microphysics also shows that the decrease in the shortwave radiative balance (albedo effect) in the simulated midlatitude cirrus cloud exceeds the net gain in the longwave balance (greenhouse effect) near midday, due to the abundance of relatively small crystals in the upper cloud region where cloud regeneration is taking place."
"55706998600;8348260700;7006686902;","Influence of soluble surfactant properties on the activation of aerosol particles containing inorganic solute",1998,"10.1175/1520-0469(1998)055<1859:IOSSPO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031713913&doi=10.1175%2f1520-0469%281998%29055%3c1859%3aIOSSPO%3e2.0.CO%3b2&partnerID=40&md5=f4608311fcc27e3444a18ef89c9b5d73","Atmospheric aerosol particles consisting of ammonium sulfate [(NH4)2SO4] or sodium chloride (NaCl) have reasonably well-defined hygroscopic properties compared to other materials in aerosol particles, such as organic material. The effect of internally mixing organic compounds with these salts is not clear when considering the hygroscopic properties of the resulting particles, including activation of particles in clouds. This research describes the activation of aerosol particles consisting of sodium dodecyl sulfate (SDS) and NaCl solute. SDS is used as a surrogate for soluble atmospheric surfactants. Köhler theory is used to model droplet activation while considering droplet properties such as surface tension (σ), surface excess surfactant concentration, and critical micelle concentration (CMC). Reduction in critical supersaturation (Sc) caused by the reduction in σ (Kelvin effect) associated with the surfactant is dominated by the increase in Sc with the decreasing number of moles of solute in the droplet (Raoult effect) as surfactant displaces NaCl solute mass. For an initially dry 0.1-μm diameter particle, Sc increases from 0.10 to 0.25 as NaCl solute mass changes from 100% (0% SDS solute) to 0% (100% SDS solute). Such dependence of cloud droplet activation on mixed solute composition is important when considering atmospheric chemistry and physics. The partitioning of materials between aerosol particles and cloud drops are influenced by mixing the surfactant with NaCl. Also, inhibition of droplet activation when displacing NaCl solute with a high molecular weight soluble surfactant could significantly influence the indirect effects aerosols have on climate change."
"6602325588;7004423756;","A comparison of TOVS ocean skin and surface air temperatures with other data sets",1998,"10.1029/97jc03417","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032523605&doi=10.1029%2f97jc03417&partnerID=40&md5=03471676bad1d9518c69fb12bf10f8a9","A data set of geophysical fields has been processed at the Goddard Laboratory for Atmospheres from Tiros operational vertical sounder (TOVS) high-resolution infrared sounder 2 (HIRS2) and microwave sounding unit (MSU) radiance observations. The retrieval system is the physically based Pathfinder Path A methodology. The data set currently covers the period 1985-1995. We compare monthly means of TOVS skin temperature Ts and surface air temperature Ta to the Tropical Ocean Global Atmosphere (TOGA) buoy observations, National Center for Environmental Prediction (NCEP) Ts, and the Comprehensive Ocean Atmosphere Data Set (COADS) Ts and Ta, for the time period 1987-1989. We also compare the Ta data to the European Center for Medium-Range Weather Forecasts (ECMWF) 2 m temperature. The TOVS Ts has a mean cold bias of 9k 0.5 K relative to NCEP Ts, while the Ta has a mean cold bias of 9k 1.0 K in the tropics relative to both ECMWF and COADS Ta. The bias in the TOVS Ta is largely due to the diurnal sampling of NOAA 10 observations. The bias in the Ts has additional contributions from a possible cool skin effect as well as retrieval errors associated with cloud clearing and accounting for water vapor attenuation and reflected solar radiation. Because of the holistic retrieval of TOVS Ts and Ta, there is a near cancellation of biases due to diurnal sampling and cloud clearing, so that the derived Ts -Ta have higher accuracy than the individual Ts and Ta, and give a more realistic representation of the evolution of known features of the ocean surface circulation than does the COADS. These results indicate that TOVS Ts and Ta may be suitable for climate variability studies involving air-sea interactions. The data set is available on a daily, 5-daily, or monthly mean basis with a spatial resolution of 1° by 1°."
"7402565763;15039674400;","Cloud condensation nuclei measurements in the high troposphere and in jet aircraft exhaust",1998,"10.1029/97GL03705","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3543145912&doi=10.1029%2f97GL03705&partnerID=40&md5=ef9331c7e8ebb231f4c69d10176a2ade","Extensive measurements of cloud condensation nuclei (CCN) spectra (1 to 0.02% supersaturation; S) at altitudes up to 12 km are presented. These were similar to many marine boundary layer measurements when normalized to standard sea level pressure. Extremely low CCN concentrations (&lt;10 cm-3) were sometimes found in association with very high CN (condensation nuclei) concentrations (&gt;3000 cm-3). This was suggestive of cloud scavenging of CCN and production of small particles. Measurements in the exhaust of a B-757 jet aircraft showed very high CCN/CN ratios and enhancements of CCN concentrations for all S. This suggests a greater impact of jet aircraft on clouds and climate than previous measurements.Extensive measurements of cloud condensation nuclei (CCN) spectral (1 to 0.02%) supersaturation; S) at altitudes up to 12 km are presented. These were similar to many marine boundary layer measurements when normalized to standard sea level pressure. Extremely low CCN concentrations (&lt;10 cm-3) were sometimes found in association with very high CN (condesation nuclei) concentrations (&gt;3000 cm-3). This was suggestive of cloud scavenging of CCN and production of small particles. Measurements in the exhaust of a B-757 jet aircraft showed very high CCN/CN ratios and enhancements of CCN concentrations for all S. This suggests a greater impact of jet aircraft on clouds and climate than previous measurements."
"7005729142;7004242319;56520921400;57191859605;7006239404;7005981420;7202108879;6603800142;","Cloud properties leading to highly reflective tropical cirrus: interpretations from CEPEX, TOGA COARE, and Kwajalein, Marshall Islands",1998,"10.1029/97JD03679","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032571694&doi=10.1029%2f97JD03679&partnerID=40&md5=7627a50601384cff3789e971d482340f","This study addresses whether high concentrations of small ice crystals in the upper 1 km or so of high, thick tropical cirrus clouds are principally responsible for the highly reflective clouds observed over the equatorial Pacific 'warm pool.' This region of the tropics has recently been shown to contain extensive shields of cirrus clouds which significantly influence the global climate through their effect on the radiation budget of the tropics. In-situ and remote sensing measurements of cloud microphysical and radiative properties from field programs in the central and western tropical Pacific and radiative transfer calculations are used to derive distributions of cloud microphysical properties with height and their relationship to cloud radiative properties. Clouds associated directly with convection are shown to have sufficiently high optical depths near cloud top to produce localized areas of bright or optically 'thick' cirrus, reflecting more than 40% of the incoming solar radiation. However, in general the upper parts of cirrus cannot alone account for the high albedos (fraction of incoming solar energy reflected) but do contribute substantially when high albedos are observed. The lower parts of the cirrus, in some cases extending down to the melting layer or below when they are called stratiform cloud regions, are usually necessary to produce high albedos."
"55745955800;8859530100;7005513582;","Bias of atmospheric shortwave absorption in the NCAR Community Climate Models 2 and 3: comparison with monthly ERBE/GEBA measurements",1998,"10.1029/98JD00343","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032571727&doi=10.1029%2f98JD00343&partnerID=40&md5=6cdee7bc47563fc2bf1088a7ca930c45","A direct comparison is made of collocated shortwave reflection at the top of the atmosphere and insolation at the surface between the National Center for Atmospheric Research Community Climate Models 2 and 3 (CCM2 and CCM3) and monthly Earth RAdiation Budget Experiment/Global Energy Balance Archive (ERBE/GEBA) measurements. It is shown that atmospheres in the models are brighter at the top of the atmosphere than ERBE measurements and meanwhile transmit more solar radiation to the surface than GEB measurements. As a consequence, the models underestimate atmospheric shortwave absorption. The amount of this underestimation is about 20 W m-2 in CCM2 and 17 W m-2 in CCM3. It is emphasized that regardless of whether the bias is in clear sky or in clouds, this underestimation has important implications for the intensity of the hydrological cycle and thus circulation in the models."
"7005691764;35571076700;7005072476;7102214342;","Transposed climates for study of water supply variability on the Laurentian Great Lakes",1998,"10.1023/A:1005351026653","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031938210&doi=10.1023%2fA%3a1005351026653&partnerID=40&md5=25d81fe6dc3e5d495272967882e0d41d","Hydrological models of the Great Lakes basin were used to study the sensitivity of Great Lakes water supplies to climate warming by driving them with meteorological data from four U.S. climate zones that were transposed to the basin. Widely different existing climates were selected for transposition in order to identify thresholds of change where major impacts on water supplies begin to occur and whether there are non-linear responses in the system. The climate zones each consist of 43 years of daily temperature and precipitation data for 1,000 or more stations and daily evaporation-related variables (temperature, wind speed, humidity, cloud cover) for approximately 20-35 stations. A key characteristic of these selected climates was much larger variability in inter-annual precipitation than currently experienced over the Great Lakes. Climate data were adjusted to simulate lake effects; however, a comparison of hydrologic results with and without lake effects showed that there was only minor effects on water supplies."
"7006211890;6603343882;7003364414;7202408184;6602417968;6602271520;6504783582;6602678543;6603598754;6504336279;","In situ measurements of the scattering phase function of stratocumulus, contrails and cirrus",1998,"10.1029/98GL00541","https://www.scopus.com/inward/record.uri?eid=2-s2.0-15644375299&doi=10.1029%2f98GL00541&partnerID=40&md5=a7e35d95382f1fbe3e34e1a39b10babb","Original measurements were obtained in stratocumulus, contrails and cirrus clouds by using a new optical airborne probe, the 'Polar Nephelometer', which is the first airborne instrument to make direct in situ measurements of the scattering phase function of cloud particles over a broad range of sizes (from a few micrometers to about 500 μm diameter). Preliminary measurements show that in stratocumulus water droplet cloud, the measured phase function fits very well with the phase function derived from direct PMS probes measurements. This definitively confirms the reliability of the Polar Nephelometer for airborne measurements. In contrails and natural cirrus, measured scattering phase function indicates major differences with those used in cloud models which assume ice spheres or simple geometric shape of ice particles. These results highlight new potential insights on both modelling of climate processes and methodologies for cloud remote sensing from satellite measurements.Original measurements were obtained in stratocumulus, contrails and cirrus clouds by using a new optical airborne probe, the `Polar Nephelometer', which is the first airborne instrument to make direct in situ measurements of the scattering phase function of cloud particles over a broad range of sizes (from a few micrometers to about 500 μm diameter). Preliminary measurements show that in stratocumulus water droplet cloud, the measured phase function fits very well with the phase function derived from direct PMS probes measurements. This definitively confirms the reliability of the Polar Nephelometer for airborne measurements. In contrails and natural cirrus, measured scattering phase function indicates major differences with those used in cloud models which assume ice spheres or simple geometric shape of ice particles. These results highlight new potential insights on both modelling of climate processes and methodologies for cloud remote sensing from satellite measurements."
"7006550762;","Latitudinal temperature gradients and climate change",1998,"10.1029/97JD03649","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032571207&doi=10.1029%2f97JD03649&partnerID=40&md5=a399db097030aedbbab78a64d43bb77f","The effects of a change in the latitudinal sea surface temperature gradient are investigated in several GCM experiments. Sea surface temperatures are increased/decreased in the tropics and polar regions, with little change in the global average surface air temperature. Then the experiments are repeated with colder/warmer conditions globally. Expectations generated from these runs are compared with the resulting climate changes in a doubled CO2 experiment and show overall agreement. Results show that the latitudinal temperature gradient governs the Hadley cell intensity, eddy energy properties, and eddy transports other than latent heat. The global mean temperature governs moisture and cloud cover, Hadley cell extent, and total rainfall. The degree of tropical and subtropical moisture changes depend on both the latitudinal gradient and the mean temperature. The Aleutian low is particularly sensitive to gradient changes, while the Icelandic low (and therefore the Greenland ice core region) is not, possibly due to orographically induced constraints in the North Atlantic. The results are then compared with paleoclimate evidence to deduce what has happened to latitudinal gradients and climate in the past. It is estimated that low-latitude temperature gradients similar to today's may have occurred in the Mesozoic and in the Little Ice Age; reduced gradients were more likely in the Pliocene, Eocene, Younger Dryas, and Last Glacial Maximum. At higher latitudes, warm climates likely had reduced temperature gradients, and cold climates increased gradients. Observed equator to pole gradients were increased in the 1980s relative to the 1950s, and the simulated climate changes consistent with observations include warming of Alaska and Asia, drying in the subtropics, and moisture variability in the US. Assignment of causes to past latitudinal gradient changes is problematic due to uncertainties concerning CO2 and ocean heat transports, but tentative conclusions based on this analysis support the likelihood of a future, higher-CO2 climate exhibiting a large low-latitude gradient and ample precipitation at middle latitudes."
"7005728145;7202139931;","Hydrophobic particles can activate at lower relative humidity than slightly hygroscopic ones: a Kohler theory incorporating surface fixed charge",1998,"10.1029/98JD00083","https://www.scopus.com/inward/record.uri?eid=2-s2.0-14444282579&doi=10.1029%2f98JD00083&partnerID=40&md5=f2a9e1f9f92c59002c0bf331636991fd","A number of laboratory experiments indicate that hydrophobic carbonaceous particles activate at lower supersaturations than is predicted by Kohler theory. Since a significant fraction of the global energy balance uncertainty is due to the so-called indirect effect, that of clouds, quantifying which particles activate is crucial to accurate prediction of climate. Most material surfaces obtain a fixed charge in water, and this is the case for many materials found in atmospheric aerosols. This fixed charge generates a charge double layer near the material surface which lowers the water activity. In the presence of this surface fixed charge, hydrophobic particles activate at low supersaturations. Since a small number of soluble ions in the particles causes them to only activate at higher supersaturations, surface charge activation is not relevant to activation of particles in the atmosphere. Thus laboratory experiments that measure the growth and activation of hydrophobic particles are measuring an effect, the surface charge effect, that is probably not relevant to the atmosphere."
"7102892446;6603569074;6603954927;57216589427;35511604900;56210623600;7402599879;","A technique for determining the spatial and temporal distributions of surface fluxes of heat and moisture over the southern Great Plains cloud and radiation testbed",1998,"10.1029/97JD03427","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032571197&doi=10.1029%2f97JD03427&partnerID=40&md5=c78e37b8d4b41e53dbd93ef1428015c3","Land surface parameterization schemes such as the Simple Biosphere Model (SiB2) have found considerable use in climate simulation models, where they provide lower boundary conditions in the form of surface sensible and latent heat fluxes. A methodology is described to apply models of this type at high resolution, using data from the Department of Energy's Cloud and Radiation Testbed in Oklahoma and Kansas, to determine the spatial variations of heat fluxes over the domain and to determine area-weighted flux averages for use in single-column model studies. Data from a dense array of meteorological instruments are interpolated to provide the wind, temperature, vapor pressure, radiation, and precipitation values needed by SiB2. The state of the vegetation is characterized through the use of the normalized difference vegetation index determined from satellites. The performance of the SiB2 model is evaluated by comparing its predictions with flux data from seven Bowen ratio stations over a 6-month period. No tuning of the model parameters for individual sites was allowed during the simulation period. Although there is significant scatter in the results, the performance of the model was generally good, accounting for over 60% of the variance in sensible heat fluxes and over 80% of the variance in latent heat fluxes. The model was therefore used to prepare 'flux maps' for the study area. These maps show large contrasts in sensible and latent heat fluxes associated primarily with differences in vegetation cover and soil moisture over the site. The differences in vegetation, in turn, result from the planting of large areas with winter wheat, which leaves some regions nearly devoid of actively growing vegetation in midsummer, while other areas are still covered with thriving crops or naturally occurring vegetation. Implications for determining large-area averages of fluxes from a limited number of measurement sites are discussed."
"7102805852;56744278700;","Global sensitivity studies of the direct radiative forcing due to anthropogenic sulfate and black carbon aerosols",1998,"10.1029/97JD03426","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032571194&doi=10.1029%2f97JD03426&partnerID=40&md5=00c1a614e4eea42a6fbbc553d5d68fef","The direct radiative forcing (DRF) of sulfate and black carbon (BC) aerosols is investigated using a new multispectral radiation code within the R30 Geophysical Fluid Dynamics Laboratory general circulation model (GCM). Two independent sulfate climatologies from chemical transport models are applied to the GCM; each climatology has a different atmospheric burden, vertical profile, and seasonal cycle. The DRF is calculated to be approximately -0.6 and -0.8 W m-2 for the different sulfate climatologies. Additional sensitivity studies show that the vertical profile of the sulfate aerosol is important in determining the DRF; sulfate residing near the surface gives the strongest DRF due to the effects of relative humidity. Calculations of the DRF due to BC reveal that the DRF remains uncertain to approximately a factor of 3 due to uncertainties in the total atmospheric burden, the vertical profile of the BC, and the assumed size distribution. Because of the uncertainties in the total global mass of BC, the normalized DRF (the DRF per unit column mass of aerosol in watts per milligram (W mg-1)) due to BC is estimated; the range is + 1.1 to + 1.9 W mg-1 due to uncertainties in the vertical profile. These values correspond to a DRF of approximately +0.4 W m-2 with a factor of 3 uncertainty when the uncertainty in the total global mass of BC is included. In contrast to sulfate aerosol, the contribution to the global DRF from cloudy regions is very significant, being estimated as approximately 60%. The vertical profile of the BC is, once again, important in determining the DRF, but the sensitivity is reversed from that of sulfate; BC near the surface gives the weakest DRF due to the shielding effects of overlying clouds. Although the uncertainty in the estimates of the DRF due to BC remains high, these results indicate that the DRF due to absorption by BC aerosol may contribute a significant positive radiative forcing and may consequently be important in determining climatic changes in the Earth-atmosphere system."
"7005882490;35464731600;","Measurements of the relationship between submicron aerosol number and volume concentration",1998,"10.1029/97JD03652","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1542709939&doi=10.1029%2f97JD03652&partnerID=40&md5=882ca59a693d84f0af13bda1fa0cf3d9","The relationship between aerosol number concentration and volume, or mass, concentration is a key linkage for the impact of aerosols on cloud albedo and thus climate forcing. Furthermore, this relationship is important in interpreting aerosol remote retrievals by satellites. We report here aircraft data, primarily from the TARFOX (Tropospheric Aerosol Radiative Forcing Experiment) study, which suggest a general linear relationship between aerosol number and mass concentration in the effective cloud condensation nucleus (CCN) size range (diameter >0.1 μn) for the locations examined. Limited data on the relationship between aerosol number concentration and chemical composition are also presented, which show a preferential dependence of effective CCN number concentration on sulfate mass. However, an implicit dependence on organic mass is also suggested."
"9233141200;7102793092;7003871110;6603695169;8945984800;16410705000;7102132806;9841756200;7004741583;7004005128;57197200637;6701801931;55435714300;","Validation of ground-based visible measurements of total ozone by comparison with Dobson and Brewer spectrophotometers",1998,"10.1023/A:1005815902581","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6844242326&doi=10.1023%2fA%3a1005815902581&partnerID=40&md5=e2e747562b666451c6280098f8a0755b","Comparisons of total column ozone measurements from Dobson, Brewer and SAOZ instruments are presented for the period 1990 to 1995 at seven stations covering the mid- and the high northern latitudes, as well as the Antarctic region. The main purpose of these comparisons is to assess, by reference to the well established Dobson network, the accuracy of the zenith-sky visible spectroscopy for the measurement of total ozone. The strengths and present limitations of this latter technique are investigated. As a general result, the different instruments are found to agree within a few percent at all stations, the best agreement being obtained at mid-latitudes. On average, for the mid-latitudes, SAOZ O3 measurements are approximately 2% higher than Dobson ones, with a scatter of about 5%. At higher latitudes, both scatter and systematic deviation tend to increase. In all cases, the relative differences between SAOZ and Dobson or Brewer column ozone are characterised by a significant seasonal signal, the amplitude of which increases from about 2.5% at mid-latitude to a maximum of 7.5% at Faraday, Antarctica. Although it introduces a significant contribution to the seasonality at high latitude, the temperature sensitivity of the O3 absorption coefficients of the Dobson and Brewer instruments is shown to be too small to account for the observed SAOZ/Dobson differences. Except for Faraday, these differences can however be largely reduced if SAOZ AMFs are calculated with realistic climatological profiles of ozone, pressure and temperature. Other sources of uncertainties that might affect the comparison are investigated. Evidence is found that the differences in the air masses sampled by the SAOZ and the other instruments contribute significantly to the scatter, and the impact of the tropospheric clouds on SAOZ measurements is displayed."
"7101667328;7202007454;","Tropical intraseasonal oscillation, super cloud clusters, and cumulus convection schemes. Part II: 3D aquaplanet simulations",1998,"10.1175/1520-0469(1998)055<0690:TIOSCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031862089&doi=10.1175%2f1520-0469%281998%29055%3c0690%3aTIOSCC%3e2.0.CO%3b2&partnerID=40&md5=b2d0bdd38ee78ad788d57948b361bf6d","Chao and Lin's work on tropical intraseasonal oscillations, super cloud clusters, and cumulus convection schemes is extended from a 2D model setup to a 3D aquaplanet setup. It is found that super cloud clusters can be simulated in a 3D model and that the 3D setup has more stringent requirements on the cumulus convection scheme than the 2D setup does for a successful simulation of super cloud clusters. Three cumulus convection schemes are compared in experiments simulating super cloud clusters. In the more successful experiments, individual cloud cluster pairs in the meridional direction, once generated near the equator by the cloud cluster tele-induction mechanism, assume a poleward movement while exhibiting weak zonal movement. The combination of two or three successive cloud cluster pairs (i.e., vortex pairs) straddling the equator gives rise to westerly wind burst events of sizable longitudinal range and duration. Thus, the westerly wind burst, as appeared in the model, is really a part of the super cloud cluster structure. The evaporation-surface wind feedback mechanism is found to be unnecessary for the existence of the super cloud clusters. However, it does make the latter more robust. The need for improvement in cumulus parameterization for tropical simulation is discussed."
"55714712500;57196499374;","Effect of clouds on direct aerosol radiative forcing of climate",1998,"10.1029/97JD03455","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3543016089&doi=10.1029%2f97JD03455&partnerID=40&md5=7e851780e6f5103dd77af025cdf6ab50","The effect of a cloud layer on top-of-atmosphere (TOA) aerosol radiative forcing is examined by means of a one-dimensional vertical column simulation. To span the range between nonabsorbing and strongly absorbing particles, (NH4)2SO4 and soot aerosols are considered individually and in internal and external mixtures. For a cloud layer embedded within an aerosol layer it is shown that direct aerosol radiative forcing still occurs. For a nonabsorbing aerosol a maximum in (negative) forcing actually occurs for a thin cloud layer (100 m thickness for the set of parameters considered). The presence of an embedded cloud layer enhances the heating effect of soot aerosol, producing, for thick clouds, forcing values as much as a factor of three over those under cloud-free conditions. An absorbing aerosol layer can lead to an increase of in-cloud solar heating rates by up to 3% for the parameter values considered here. A cirrus cloud layer above an aerosol layer leads to only modest changes of TOA aerosol forcing from those in the absence of the cloud layer; thus aerosol forcing in the presence of typical cirrus clouds cannot be neglected."
"7409074131;7007085057;","Adjoint sensitivity of the Earth's radiation budget in the NCEP medium-range forecasting model",1998,"10.1029/97JD03631","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0005058998&doi=10.1029%2f97JD03631&partnerID=40&md5=e7768f9c791e5bf053d0084dcf5fa50a","We introduced an adjoint technique to study sensitivity of the Earth's radiation budget (ERB) to cloud cover, water vapor, atmospheric temperature, and the Earth's surface temperature. This technique allowed us to calculate the partial derivatives of a defined ERB function with respect to all of the above variables on the model grid points by a single calculation of the adjoint model. We employed the radiation model of the National Centers for Environmental Prediction medium-range forecasting system to perform such an adjoint sensitivity analysis. For clear sky the absorbed shortwave radiation (ASR) was mcuh more sensitive to the water vapor in the middle troposphere at high latitudes in the summer time hemisphere than at the tropical and subtropical areas. The outgoing longwave radiation (OLR) was one order of magnitude more sensitive to water vapor mixing ratios in the upper troposphere than to those in the middle and lower troposphere. In the tropics, more than 80% of a perturbation increase in the Earth's surface emission was trapped by the clear-sky column atmosphere, while only about 60-70% is trapped at middle and high latitudes. Rapidly decreasing latitude bands of trapping were found within the subtropics, and the semipermanent troughs over the central oceans displayed a significant effect. For the case of cloudy sky the ASR was more sensitive to low clouds than to middle and high clouds. The most sensitive low clouds tended to be located at midlatitudes rather than in the tropical regions. The OLR, as expected, was most sensitive to high clouds and displayed similar sensitivity to middle clouds. The net ERB was most sensitive to low clouds at midlatitudes in the summer hemisphere. The relationship between the results obtained and the greenhouse effect over tropical oceans as well as the influence of clouds on the climate change were explored, and some model deficiencies were discussed."
"7402219524;6603162301;7006683195;7005942405;","Uncertainty analysis of indirect radiative forcing by anthropogenic sulfate aerosols",1998,"10.1029/97JD02809","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046500953&doi=10.1029%2f97JD02809&partnerID=40&md5=2eaedae8fa800ee950be773909e8abde","The effects of aerosols on the optical properties of water clouds (so-called indirect aerosol effects) are a major current source of uncertainty in the radiative forcing of climate change. Uncertainty in the indirect radiative forcing by anthropogenic sulfate aerosls is analyzed for five different model structures with 20 input uncertain parameters using the probabilistic collocation method. The structural uncertainty, measuring the range of the mean responses in different models, is -1.2 to -1.7 W m-2, and the parametric uncertainty, induced by the uncertainties in the input model parameters, is -0.1 to -5.2 W m-2 with 95% confidence. This implies that refining the input parameters may be more important than improving models in order to minimize the uncertainty in the indirect radiative forcing by anthropogenic sulfate aerosols using these five models. The rankings of sensitivity to and variance contribution by the 20 uncertrain parameters shows very different patterns. The variance analysis indicates that the parametric uncertainty comes mainly from aerosol size parameters and atmospheric transmittance, indicating the importance of developing size-resolved global aerosol models. Although the conclusions reached here are subject to the choice of model structures and uncertain parameter distributions, this study introduces a useful framework for computing uncertainty in a critical climate issue."
"7402219524;6603162301;7006683195;7005942405;","Uncertainty analysis of indirect radiative forcing by anthropogenic sulfate aerosols",1998,"10.1029/973D02809","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0004658788&doi=10.1029%2f973D02809&partnerID=40&md5=f249fe9f8b435e1493ddb6f8d08bc150","The effects of aerosols on the optical properties of water clouds (socalled indirect aerosol effects) are a major current sonrce of uncertainty in the radiative forcing of climate change. Uncertainty in the indirect radiative forcing by anthropogenic sulfate aerosols is analyzed for five different model structures with 20 input uncertain parameters using the probabilistic collocation method. The structural uncertainty, measuring the range of the mean responses in different models. is -1.2 to -1.7 W m-2 and the parametric uncertainty, induced by the uncertainties in the input model parameters, is -0.1 to -5.2 W m-2 with 95% confidence. This implies that refining the input parameters may be more important than improving models in order to minimize the uncertainty in the indirect radiative forcing by anthropogenic sulfate aerosols using these five models. The rankings of sensitivity to and variance contribution by the 20 uncertain parameters shows very different patterns. The variance analysis indicates that the parametric uncertainty comes mainly from aerosol size parameters and atmospheric transmittance, indicatiug the importance of developing size-resolved global aerosol models. Although the conclusions reached here are subject to the choice of model structures and nncertain parameter distributions, this study introduces a useful framework for computing uncertainty in a critical climate issue. © 1998 by the American Geophysical Union."
"7003828850;6603272945;35508431200;7103239241;","Climatology of the daily temperature range annual cycle in the United States",1998,"10.3354/cr009197","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031817187&doi=10.3354%2fcr009197&partnerID=40&md5=a8653087c0e79fc02295c59ac9092bc3","Many researchers are presently interested in detecting long-term trends in annual or seasonal daily temperature range (DTR), and attributing these changes to anthropogenic origins. However, very little work has been done to confirm the mechanisms that are important to determining the long-term average annual cycle of the DTR. Therefore, the focus of this work is to examine the spatial and temporal difference in the DTR average annual cycle across the United States, and to associate the patterns of these cycles with potential causal variables. Three major types of DTR annual cycle exist in the United States: high sun season maximum (northern and western U.S.), low sun season maximum (south central and southeast U.S.), and transitional season maxima (middle latitude in the U.S.). The annual cycles of the DTR in the northern and western U.S. are well related to average annual cycles of cloud cover and dew point temperature; only areas to the west of the Rocky Mountains have a strong linkage between DTR and precipitation frequency annual cycles. Across the northern tier of the U.S., the loss of snow cover is important to DTR transitions during the spring season. However, the onset of snow cover in the fall does not appear to be the major factor in DTR variations, which are instead more strongly associated with cloud cover effects. As expected from their sinusoidal annual cycle, maximum and minimum temperature cycles are linearly related to the DTR in regions with a warm season or cold season DTR maximum, while non-linear relationships exist where the DTR annual cycle has maxima in the transition seasons."
"7202803069;7006133602;","Extreme daily rainfall in southern African and Southwest Indian Ocean tropical-temperate links",1998,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031829484&partnerID=40&md5=5753f2e80942c96346c8ecdd3c642165","The structure of daily austral summer rainfall variability over southern Africa and the Southwest Indian Ocean has been analysed objectively by calculating empirical orthogonal functions of daily rainfall over both land and ocean. Daily rainfall is calculated from recently released satellite products from the International Satellite Cloud Climatology Programme (ISCCP). Tropical-temperate links are the main mode of daily rainfall variability in the region for each of the summer months of November to March. These links are orientated northwest to southeast with a locus of activity over Zambia, Zimbabwe and Mozambique, extending to the Southwest Indian Ocean near 40°S and 50°E. In all months except February, these links have a dipole structure such that enhanced (suppressed) convection over the northwest to southeast-orientated band described above is associated with suppressed (enhanced) convection over a similarly orientated band with maxima over Namibia, South Africa and the Southern Ocean near 35°S and 30°E. Events characterised by such tropical-temperate connections are relatively infrequent and exhibit marked interannual variability. Average rainfall anomalies associated with composites of the major extreme temperate-tropical events peak at 8-10 mm per day in each month. The proportional contribution of this small number of extreme events to total rainfall is substantial, and tends to be highest over ocean regions."
"7402717381;7006865796;7004378017;57206505383;7006861480;","Midlatitude cyclonic cloud systems and their features affecting large scales and climate",1998,"10.1029/97RG03573","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031849849&doi=10.1029%2f97RG03573&partnerID=40&md5=8462cc12a558bbdb4ddc63e8b2e4af26","Midlatitude cyclonic cloud systems are common occurrences that significantly impact our climate. In this review, attention is paid to those physical characteristics of these cloud systems with large-scale impacts that must be accounted for in climate simulations. Such attributes include atmospheric forcing, internal structure, surface influences, cloud layering, microphysics, precipitation, water cycling, and radiation. Because of their present limitations associated with, for example, grid sizes and simplified parameterizations, climate models cannot account for all the crucial impacts of these cloud systems. Future advances in the representation of these systems within climate models will need to rely in part on rigorous assessments of model capabilities in a variety of conditions."
"7404653593;7201844203;35497573900;7401559815;","Effect of ice cloud on GCM climate simulations",1998,"10.1029/97GL03356","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031804582&doi=10.1029%2f97GL03356&partnerID=40&md5=7f0918457592c802a9a3d9f3a684ce25","The effect of the interaction of SW (shortwave, solar) radiation with ice clouds on climate simulations is studied using the GEOS (Goddard Earth Observing System) climate GCM (general circulation model) coupled with an ocean mixed-layer model. Due to much larger cloud particles, the single-scattering co-albedo of ice clouds is nearly ten times larger than that of water clouds, but the asymmetry factor is generally smaller. Offline calculations with a radiative transfer model show that inclusion of the ice cloud effect increases SW absorption in the upper troposphere and decreases the SW flux at the surface. For the earth-atmosphere system, the change in the SW absorption is small due to compensation of the co-albedo and asymmetry factor effects. The effect of ice clouds tends to increase the atmospheric stability by enhancing SW heating in the upper troposphere and reducing SW heating in the lower troposphere and at the surface. The GCM experiments demonstrate that the inclusion of ice clouds produces colder surface temperature, and leads to reduction in SW heating of the earth-atmosphere system associated with changes in surface albedo and in cloud distribution. The enhanced atmospheric stability leads to decreased high cloud amount by a maximum of 80% and to increased middle cloud by a maximum of 60% over the tropics."
"7005814217;","Sensitivity of the Simulated Climate to a Diagnostic Formulation for Cloud Liquid Water",1998,"10.1175/1520-0442(1998)011<1497:SOTSCT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000853920&doi=10.1175%2f1520-0442%281998%29011%3c1497%3aSOTSCT%3e2.0.CO%3b2&partnerID=40&md5=b6cc6e575b20324edfebf686f87d1ace","The accurate treatment of clouds and their radiative properties is widely regarded to be among the most important problems facing global climate modeling. A number of the more serious systematic simulation biases in the NCAR Community Climate Model (CCM2) appear to be related to deficiencies in the treatment of cloud optical properties. In this paper, a simple diagnostic parameterization for cloud liquid water is presented. The sensitivity of the simulated climate to this alternative formulation, both in terms of mean climate metrics and measures of the climate system response, is illustrated. Resulting simulations show significant reductions in CCM2 systematic biases, particularly with respect to surface temperature, precipitation, and extratropical geopotential height-field anomalies. Many aspects of the simulated response to ENSO forcing are also substantially improved."
"6603422104;57193132723;6507993848;7403318365;","Temperature dependence of low cloud optical thickness in the GISS GCM: Contributing mechanisms and climate implications",1998,"10.1175/1520-0442(1998)011<3268:TDOLCO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032412980&doi=10.1175%2f1520-0442%281998%29011%3c3268%3aTDOLCO%3e2.0.CO%3b2&partnerID=40&md5=5441efa39820e3f36fcb6234e9646218","A current-climate simulation of the Goddard Institute for Space Studies (GISS) GCM, which includes interactive cloud optical properties that depend on the predicted cloud water content, is analyzed to document the variations of low cloud optical thickness with temperature in the model atmosphere. It is found that low cloud optical thickness decreases with temperature in the warm subtropical and tropical latitudes and increases with temperature in the cold midlatitude regions. This behavior is in agreement with the results of two observational studies that analyzed satellite data from the International Satellite Cloud Climatology Project and Special Sensor Microwave/Imager datasets. The increase of low cloud optical thickness with temperature in the midlatitudes is due to vertical extent and cloud water increases, whereas the decrease with temperature in the warm latitudes is due to decreases in cloud water content and happens despite increases in cloud vertical extent. The cloud processes that produce the cloud property changes in the model also vary with latitude. In the midlatitude regions relative-humidity-induced increases of cloud vertical extent with temperature dominate, whereas in the Tropics increases in cloud-top entrainment and precipitation with temperature produce decreases of cloud water content, whose effect on optical thickness outweighs the effect of entrainment-induced increases of cloud vertical extent with temperature. Doubled-CO2 simulations with the GISS GCM suggest that even though low cloud optical thickness changes have little effect on the global climate sensitivity of the model, they redistribute the temperature change and reduce the high-latitude amplification of the greenhouse warming. It is also found that the current-climate variations of low cloud optical thickness with temperature reproduce qualitatively but overestimate quantitatively the changes in optical thickness with climate warming.A current-climate simulation of the Goddard Institute for Space Studies (GISS) GCM, which includes interactive cloud optical properties that depend on the predicted cloud water content, is analyzed to document the variations of low cloud optical thickness with temperature in the model atmosphere. It is found that low cloud optical thickness decreases with temperature in the warm subtropical and tropical latitudes and increases with temperature in the cold midlatitude regions. This behavior is in agreement with the results of two observational studies that analyzed satellite data from the International Satellite Cloud Climatology Project and Special Sensor Microwave/Imager datasets. The increase of low cloud optical thickness with temperature in the midlatitudes is due to vertical extent and cloud water increases, whereas the decrease with temperature in the warm latitudes is due to decreases in cloud water content and happens despite increases in cloud vertical extent. The cloud processes that produce the cloud property changes in the model also vary with latitude. In the midlatitude regions relative-humidity-induced increases of cloud vertical extent with temperature dominate, whereas in the Tropics increases in cloud-top entrainment and precipitation with temperature produce decreases of cloud water content, whose effect on optical thickness outweighs the effect of entrainment-induced increases of cloud vertical extent with temperature. Doubled-CO2 simulations with the GISS GCM suggest that even though low cloud optical thickness changes have little effect on the global climate sensitivity of the model, they redistribute the temperature change and reduce the high-latitude amplification of the greenhouse warming. It is also found that the current-climate variations of low cloud optical thickness with temperature reproduce qualitatively but overestimate quantitatively the changes in optical thickness with climate warming."
"7004828383;6507797248;56283400100;6506101358;6603906450;","Cloud processes associated with past and future climate changes",1998,"10.1007/s003820050220","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031817432&doi=10.1007%2fs003820050220&partnerID=40&md5=93670addf01c072721373a3127fbe066","To investigate the cloud response during cold and warm periods, we have performed simulations of the Last Glacial Maximum (LGM-21ky BP) and of double CO2 concentration using the LMD AGCM model. We observe that the thermal characteristics of these two climates are opposite, but the cloud response is more complex and does not display the same symmetry When doubling the CO2, the warming of the troposphere and the cooling of the stratosphere are clearly linked with a reduction in low-level clouds and an increase of high-level clouds associated with relative humidity changes. For the LGM, the cloud response is more complex. In the inter tropical region, we show that the Hadley cell is reinforced during LGM (+20%) whereas it is reduced (-10%) for the double CO2 experiments. The most important feature is that we observe an enlarged Hadley cell for LGM climate which strongly modifies the atmospheric dynamics and water transport. For LGM conditions, the cloud response is then mostly driven by these dynamical changes at low latitudes though at high latitudes the thermal changes explain a large part of the cloud response. Two different versions of the model, using different parametrizations for the precipitation show that cloud feedbacks may act differently for cold and warm climates; and that the cloud response may be more complex that previously expected, but also indicate that the details of these effects are model dependent."
"57218998197;7006708207;57205966542;57216095716;","Role of sea salt aerosol in the indirect radiative forcing of climate",1998,"10.1016/S0021-8502(98)00102-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0039526763&doi=10.1016%2fS0021-8502%2898%2900102-5&partnerID=40&md5=8c3fd4253d7154279464ca7da503fa1e",[No abstract available]
"55087038900;7403931916;35779178900;","An accurate parameterization of the infrared radiative properties of cirrus clouds for climate models",1998,"10.1175/1520-0442(1998)011<2223:AAPOTI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032463620&doi=10.1175%2f1520-0442%281998%29011%3c2223%3aAAPOTI%3e2.0.CO%3b2&partnerID=40&md5=2f8c23dc177b1ffae031c06cda08fbb1","An accurate parameterization is presented for the infrared radiative properties of cirrus clouds. For the single-scattering calculations, a composite scheme is developed for randomly oriented hexagonal ice crystals by comparing results from Mie theory, anomalous diffraction theory (ADT), the geometric optics method (GOM), and the finite-difference time domain technique. This scheme employs a linear combination of single-scattering properties from the Mie theory, ADT, and GOM, which is accurate for a wide range of size parameters. Following the approach of Q. Fu, the extinction coefficient, absorption coefficient, and asymmetry factor are parameterized as functions of the cloud ice water content and generalized effective size (D(ge)). The present parameterization of the single-scattering properties of cirrus clouds is validated by examining the bulk radiative properties for a wide range of atmospheric conditions. Compared with reference results, the typical relative error in emissivity due to the parameterization is ~2.2%. The accuracy of this parameterization guarantees its reliability in applications to climate models. The present parameterization complements the scheme for the solar radiative properties of cirrus clouds developed by Q. Fu for use in numerical models."
"6701331144;7005206400;57213844575;7004910963;","A comparison of Amazonian climate data with general circulation model simulations",1998,"10.1175/1520-0442(1998)011<2764:ACOACD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032216392&doi=10.1175%2f1520-0442%281998%29011%3c2764%3aACOACD%3e2.0.CO%3b2&partnerID=40&md5=014542f034d138931fe93ad87f39df2a","Climate data from the Anglo-Brazilian Amazonian Climate Observation Study have been compared with the simulations of three general circulation models with prognostic cloud schemes. Monthly averages of net allwave radiation, incoming solar radiation, net longwave radiation, and precipitation obtained from automatic weather stations sited in three areas of Amazonia are compared with the output from the unified model of the Hadley Centre for Climate Prediction and Research, the operational forecasting model of the European Centre for Medium-Range Weather Forecasts (ECMWF), and the model of the Laboratoire de Meteorologie Dynamique (LMD). The performance of the models is much improved when compared to comparisons of observations with the output from earlier, less sophisticated models. However, the Hadley Centre and LMD models tend to overpredict net and solar radiation, and the ECMWF model underpredicts net and solar radiation at two of the sites, but performs very well in Manaus. It is shown that the errors are mainly linked to the amount of cloud cover produced by the models, but also to the incoming clear sky solar radiation.Climate data from the Anglo-Brazilian Amazonian Climate Observation Study have been compared with the simulations of three general circulation models with prognostic cloud schemes. Monthly averages of net all-wave radiation, incoming solar radiation, net longwave radiation, and precipitation obtained from automatic weather stations sited in three areas of Amazonia are compared with the output from the unified model of the Hadley Centre for Climate Prediction and Research, the operational forecasting model of the European Centre for Medium-Range Weather Forecasts (ECMWF), and the model of the Laboratoire de Meteorologie Dynamique (LMD). The performance of the models is much improved when compared to comparisons of observations with the output from earlier, less sophisticated models. However, the Hadley Centre and LMD models tend to overpredict net and solar radiation, and the ECMWF model underpredicts net and solar radiation at two of the sites, but performs very well in Manaus. It is shown that the errors are mainly linked to the amount of cloud cover produced by the models, but also to the incoming clear sky solar radiation."
"7006246996;55723064900;7005634455;7102577095;56165006900;7004993886;","The impact of antarctic cloud radiative properties on a GCM climate simulation",1998,"10.1175/1520-0442(1998)011<0447:TIOACR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031879298&doi=10.1175%2f1520-0442%281998%29011%3c0447%3aTIOACR%3e2.0.CO%3b2&partnerID=40&md5=1369e2f225f6b3b7091abdae1661b1e8","A sensitivity study to evaluate the impact upon regional and hemispheric climate caused by changing the optical properties of clouds over the Antarctic continent is conducted with the NCAR Community Model version 2 (CCM2). Sensitivity runs are performed in which radiation interacts with ice clouds with particle sizes of 10 and 40 μm rather than with the standard 10-μm water clouds. The experiments are carried out for perpetual January conditions with the diurnal cycle considered. The effects of these cloud changes on the Antarctic radiation budget are examined by considering cloud forcing at the top of the atmosphere and net radiation at the surface. Changes of the cloud radiative properties to those of 10-μm ice clouds over Antarctica have significant impacts on regional climate: temperature increases throughout the Antarctic troposphere by 1°-2°C and total cloud fraction over Antarctica is smaller than that of the control at low levels but is larger than that of the control in the mid-to upper troposphere. As a result of Antarctic warming and changes in the north-south temperature gradient, the drainage flows at the surface as well as the meridional mass circulation are weakened. Similarly, the circumpolar trough weakens significantly by 4-8 hPa and moves northward by about 4°-5° latitude. This regional mass field adjustment halves the strength of the simulated surface westerly winds. As a result of indirect thermodynamic and dynamic effects, significant changes are observed in the zonal mean circulation and eddies in the middle latitudes. In fact, the simulated impacts of the Antarctic cloud radiative alteration are not confined to the Southern Hemisphere. The meridional mean mass flux, zonal wind, and latent heat release exhibit statistically significant changes in the Tropics and even extratropics of the Northern Hemisphere. The simulation with radiative properties of 40-μm ice clouds produces colder surface temperatures over Antarctica by up to 3°C compared to the control. Otherwise, the results of the 40-μm ice cloud simulation are similar to those of the 10-μm ice cloud simulation."
"7005807606;55666570300;7201351738;7004052140;7103184162;6507146805;","An Unattended Cloud-Profiling Radar for Use in Climate Research",1998,"10.1175/1520-0477(1998)079<0443:AUCPRF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000257257&doi=10.1175%2f1520-0477%281998%29079%3c0443%3aAUCPRF%3e2.0.CO%3b2&partnerID=40&md5=fdc3910a8c6f8596713795a8e10c6c9e","A new millimeter-wave cloud radar (MMCR) has been designed to provide detailed, long-term observations of nonprecipitating and weakly precipitating clouds at Cloud and Radiation Testbed (CART) sites of the Department of Energy's Atmospheric Radiation Measurement (ARM) program. Scientific requirements included excellent sensitivity and vertical resolution to detect weak and thin multiple layers of ice and liquid water clouds over the sites and long-term, unattended operations in remote locales. In response to these requirements, the innovative radar design features a vertically pointing, single-polarization, Doppler system operating at 35 GHz (Ka band). It uses a low-peak-power transmitter for long-term reliability and high-gain antenna and pulse-compressed waveforms to maximize sensitivity and resolution. The radar uses the same kind of signal processor as that used in commercial wind profilers. The first MMCR began operations at the CART in northern Oklahoma in late 1996 and has operated continuously there for thousands of hours. It routinely provides remarkably detailed images of the ever-changing cloud structure and kinematics over this densely instrumented site. Examples of the data are presented. The radar measurements will greatly improve quantitative documentation of cloud conditions over the CART sites and will bolster ARM research to understand how clouds impact climate through their effects on radiative transfer. Millimeter-wave radars such as the MMCR also have potential applications in the fields of aviation weather, weather modification, and basic cloud physics research."
"7005513582;7005814217;7005557215;7003684963;7402435469;7006705919;","The National Center for Atmospheric Research Community Climate Model: CCM3",1998,"10.1175/1520-0442(1998)011<1131:TNCFAR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031718804&doi=10.1175%2f1520-0442%281998%29011%3c1131%3aTNCFAR%3e2.0.CO%3b2&partnerID=40&md5=8fc10fab6d2e676562d44adb080a7d34","The latest version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM3) is described. The changes in both physical and dynamical formulation from CCM2 to CCM3 are presented. The major differences in CCM3 compared to CCM2 include changes to the parameterization of cloud properties, clear sky longwave radiation, deep convection, boundary layer processes, and land surface processes. A brief description of each of these parameterization changes is provided. These modifications to model physics have led to dramatic improvements in the simulated climate of the CCM. In particular, the top of atmosphere cloud radiative forcing is now in good agreement with observations, the Northern Hemisphere winter dynamical simulation has significantly improved, biases in surface land temperatures and precipitation have been substantially reduced, and the implied ocean heat transport is in very good agreement with recent observational estimates. The improvement in implied ocean heat transport is among the more important attributes of the CCM3 since it is used as the atmospheric component of the NCAR Climate System Model. Future improvements to the CCM3 are also discussed."
"7201386171;36789199700;7102661133;6507112437;7409788341;","Preliminary laboratory studies of the optical scattering properties of the crystal clouds",1998,"10.1007/s00585-998-0618-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0542399104&doi=10.1007%2fs00585-998-0618-4&partnerID=40&md5=f08338464fa8336cd8ed6fd7cc9c797f","Ice crystal clouds have an influence on the radiative budget of the earth; however, the exact size and nature of this influence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90° than do water droplets, and that the halo effects are visible in a laboratory-generated cloud when the ice crystal concentration is sufficiently small to prevent masking from multiple scattering."
"35600074800;7004858482;7005287667;7004296083;7405551904;7003740015;","Turbulent aerosol number fluxes over sea and pack ice: Deposition and wind driven fluxes of sub micrometer aerosol",1998,"10.1016/S0021-8502(98)00160-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038932837&doi=10.1016%2fS0021-8502%2898%2900160-8&partnerID=40&md5=7ad30e4f3c34dfec867bbb5ab428878b",[No abstract available]
"16170561000;7005088845;7006634316;","Aerosol particles and clouds: Which particles form cloud droplets?",1998,"10.3402/tellusb.v50i1.16024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031982298&doi=10.3402%2ftellusb.v50i1.16024&partnerID=40&md5=83f6816e4134625e069f8945c883bb2b","Measurements of cloud droplet residuals, which represent the cloud droplet nuclei (CDN) that formed cloud droplets, were made in ambient clouds with a 1-min time resolution. Only a weak relationship was found between the CDN number and volume concentrations, because the particles dominating the two concentrations resided in different size ranges. A comparison between the total particle size distribution and the size distribution of the CDN showed that only a small fraction of the total number of particles at a given size (smaller than 0.2 μm diameter) formed cloud droplets. Among the CDN, however, 75% of the number of particles were smaller than 0.2 μm diameter. Concurrent measurements showed that hygroscopic particles of the same size and larger remained in the interstitial air. The same feature was observed over longer time periods on a 1-min basis. Suggested hypotheses to explain why only a few of the smaller hygroscopic particles formed cloud droplets while larger particles remained in the interstitial air are that the growth of the droplet could have been influenced by the composition of individual particles and/or that entrainment introduced hygroscopic particles in the interstitial air."
"7005956183;7005421048;6603892183;7003309358;7005067383;7102661133;15124069000;56152167900;","Cloud-radiation studies during the European cloud and radiation experiment (EUCREX)",1998,"10.1023/A:1006544220339","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031845101&doi=10.1023%2fA%3a1006544220339&partnerID=40&md5=f5700f22c8c1504fe0616a053126cf6c","The dominant role of clouds in modulating and interacting with radiative energy transports within the atmosphere, in providing precipitation, transporting water and influencing air-chemical processes is still not understood well enough to be accurately represented within atmospheric circulation and climate models over all regions of the globe. Also the extraction of real-world cloud properties from satellite measurements still contains uncertainties. Therefore, various projects have been developed within the Global Energy and Water Cycle Experiment (GEWEX), to achieve more accurate solutions for this problem by direct measurements within cloud fields and other complementary studies. They are based on the hypothesis, that most relevant properties of cloud fields can be parametrized on the basis of the prognostic field variables of atmospheric circulation models, and that the cloud microphysical properties can directly be related - with additional parameters on the particle shapes etc.-to the radiative transfer properties. One of these projects has been the European Cloud and Radiation Experiment (EUCREX) with its predecessor ICE (International Cirrus Experiment). The EUCREX and ICE provided a common platform for research groups from France, Germany, Sweden and the United Kingdom to concentrate their efforts primarily on high, cold cirrus. They showed, with data from satellites, that this cloud species enhances the atmospheric greenhouse-effect. Numerical mesoscale models were used in sensitivity studies on cloud developments. In-situ measurements of cloud properties were made during more than 30 aircraft missions, where also inflight comparisons of various instruments were made to ensure the quality of data sets measured from different aircraft. The particle sampling probes, used for in-cloud measurements, showed a disagreement in total number density in all ranges between about 20-50%, while all other instruments agreed quite satisfactorily. A few measured holographic data provided information on typical ice-crystal shapes, which were used in numerical simulations of their absorption and scattering properties. Several new instruments for both in-situ and remote measurement, such as a polar nephelometer, a chopped pyrgeometer and an imaging multispectral polarimeter (POLDER) for cloud and radiation measurements were tested and improved. New algorithms were developed for cloud classifications in multispectral satellite images and also for simulations of the scattering of radiation by non-spherical particles. This paper primarily summarizes the EUCREX results obtained between 1989 and 1996, and provides examples of the many results which have been obtained so far. It is not a complete review of the world-wide state in this field, but it tries to place the EUCREX results into the world-wide development. Therefore many references are made to the results of other groups, which in turn influenced the work within EUCREX."
"7006705919;7005955015;","A Comparison of the CCM3 Model Climate Using Diagnosed and Predicted Condensate Parameterizations",1998,"10.1175/1520-0442(1998)011<1587:ACOTCM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1542607870&doi=10.1175%2f1520-0442%281998%29011%3c1587%3aACOTCM%3e2.0.CO%3b2&partnerID=40&md5=1b32908f5e4173e0e9211b56ebfbf7fc","A parameterization is introduced for the prediction of cloud water in the National Center for Atmospheric Research Community Climate Model version 3 (CCM3). The new parameterization makes a much closer connection between the meteorological processes that determine condensate formation and the condensate amount. The parameterization removes some constraints from the simulation by allowing a substantially wider range of variation in condensate amount than in the standard CCM3 and tying the condensate amount to local physical processes. The parameterization also allows cloud drops to form prior to the onset of grid-box saturation and can require a significant length of time to convert condensate to a precipitable form, or to remove the condensate. The free parameters of the scheme were adjusted to provide reasonable agreement with top of atmosphere and surface fluxes of energy. The parameterization was evaluated by a comparison with satellite and in situ measures of liquid and ice cloud amounts. The effect of the parameterization on the model simulation was then examined by comparing long model simulations to a similar run with the standard CCM and through comparison with climatologies based upon meteorological observations. Global ice and liquid water burdens are higher in the revised model than in the control simulation, with an accompanying increase in height of the center of mass of cloud water. Zonal averages of cloud water contents were 20%-50% lower near the surface and much higher above. The range of variation of cloud water contents is much broader in the new parameterization but was still not as large as measurements suggest. Differences in the simulation were generally small. The largest significant changes found to the simulation were seen in polar regions (winter in the Arctic and all seasons in the Antarctic). The new parameterization significantly changes the Northern Hemisphere winter distribution of cloud water and improves the simulation of temperature and cloud amount there. Small changes were introduced in the cloud fraction to improve consistency of the meteorological parameterizations and to attempt to alleviate problems in the model (in particular, in the marine stratocumulus regime). The small changes did not make any appreciable improvement to the model simulation. The new parameterization adds significantly to the flexibility in the model and the scope of problems that can be addressed. Such a scheme is needed for a reasonable treatment of scavenging of atmospheric trace constituents, and cloud aqueous or surface chemistry. The addition of a more realistic condensate parameterization provides opportunities for a closer connection between radiative properties of the clouds, and their formation and dissipation. These processes must be treated for many problems of interest today (e.g., anthropogenic aerosol-climate interactions)."
"57202163835;6506101358;57203200427;24511929800;","Sulfate Aerosol Indirect Effect and CO2 Greenhouse Forcing: Equilibrium Response of the LMD GCM and Associated Cloud Feedbacks",1998,"10.1175/1520-0442(1998)011<1673:saieac>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001733727&doi=10.1175%2f1520-0442%281998%29011%3c1673%3asaieac%3e2.0.co%3b2&partnerID=40&md5=fe5f577fffe3bfe82cc93c068cf4ce19","The climate sensitivity to various forcings, and in particular to changes in CO2 and sulfate aerosol concentrations, imposed separately or in a combined manner, is studied with an atmospheric general circulation model coupled to a simple slab oceanic model. The atmospheric model includes a rather detailed treatment of warm cloud microphysics and takes the aerosol indirect effects into account explicitly, although in a simplified manner. The structure of the model response appears to be organized at a global scale, with a partial independence from the geographical structure of the forcing. Atmospheric and surface feedbacks are likely to explain this feature. In particular the cloud feedbacks play a very similar role in the CO2 and aerosol experiments, but with opposite sign. These results strengthen the idea, already apparent from other studies, that, in spite of their different nature and their different geographical and vertical distributions, aerosol may have substantially counteracted the climate effect of greenhouse gases, at least in the Northern Hemisphere, during the twentieth century. When the effects of the two forcings are added, the model response is not symmetric between the two hemispheres. This feature is also consistent with the findings of other modeling groups and has implications for the detection of future climate changes."
"6603809220;","A physically based scheme for the treatment of stratiform clouds and precipitation in large-scale models. II: Comparison of modelled and observed climatological fields",1998,"10.1002/qj.49712454603","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031800197&doi=10.1002%2fqj.49712454603&partnerID=40&md5=d030da59511a52722c334d099f5f9957","Fields from two experiments performed with 18-level versions of the Commonwealth Scientific and Industrial Organization (CSIRO) global climate model (GCM) are compared with observed fields, focusing on quantities related to clouds and precipitation. The first experiment (denoted by PROG) employed a new prognostic treatment of stratiform clouds and precipitation, while the second experiment (denoted by DIAG18) employed a diagnostic treatment, similar to that used in the standard 9-level CSIRO GCM. The main findings are as follows. • Global-mean quantities agree well with observations, although the global cloudiness in both runs is a little lower than observed values. • Zonal-mean fields generally show good to very good agreement with observations, particularly in the PROG run, where marked improvements in the cloudiness and long-wave cloud radiative forcing (LWCF) at high latitudes are noted. The PROG run has cloud-liquid-water paths (LWPs) that are larger over mid-latitude oceans than those from satellite retrievals. • Geographical distributions of precipitation, cloudiness, LWCF and SWCF (short-wave cloud radiative forcing) from both runs are generally in reasonable agreement with observations. Overall, the cloudiness and LWCF are somewhat more realistic in the PROG run, the SWCF is slightly more realistic in the DIAG18 run, and the precipitation is not greatly affected by the change of cloud scheme. • Problems affecting both runs to some degree are: deficient cloudiness in the subtropics, and to a lesser extent in mid-latitudes; deficient SWCF in mid-latitudes, with a tendency towards excessive SWCF at low latitudes; deficient LWCF over land, mainly in the tropics and northern mid-latitudes; excessive precipitation, cloudiness and cloud radiative forcing in the tropical western Pacific Ocean in July. The reasons for the above findings are investigated, in part, via the use of sensitivity tests. The improved high-latitude cloudiness in the PROG run results from (a) replacement of a cloudiness parametrization based on relative humidity with one based on a generalized relative humidity that includes the contribution from cloud water, and (b) inclusion of the effect of frozen precipitation processes on the cloud fraction. The improved LWCF is primarily the result of more realistic treatment of cloud emissivity in the prognostic cloud scheme. The excessive LWPs over mid-latitude oceans in the PROG run can be corrected by a modest reduction in the critical cloud droplet radius that controls the onset of autoconversion. The deficient cloudiness in the subtropics and mid-latitudes (typical of current GCMs) can be improved by simple changes to the critical relative humidities used to control the onset of cloud formation or by an increase of vertical resolution, but this improvement comes at the cost of excessive cloudiness in the tropics. The errors in the modelled SWCF (also typical of current GCMs) suggest that there is a systematic latitudinal bias in the calculation of cloud-radiation interactions, such as the effect of solar zenith angle. The deficient LWCF over land is related to a deficiency of high cloud. The vigorous circulation in July over the tropical western Pacific is much more prominent in these 18-level simulations than in the standard 9-level version of the model, and is related to aspects of the model other than the cloud treatment."
"7003591311;57216303228;7103289129;25953950400;","Feasibility of retrieving cloud condensation nucleus properties from doppler cloud radar, microwave radiometer, and lidar",1998,"10.1175/1520-0426(1998)015<1188:FORCCN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032450416&doi=10.1175%2f1520-0426%281998%29015%3c1188%3aFORCCN%3e2.0.CO%3b2&partnerID=40&md5=f20d7a8caf15276fdcec26890a653833","This paper explores the possibilities of using Ka-band Doppier radar, microwave radiometer, and lidar as a means of retrieving cloud condensation nucleus (CCN) properties in the stratocumulus-capped marine boundary layer. The retrieval is based on the intimate relationship between the cloud drop number concentration, the vertical air motion at cloud base, and the CCN activation spectrum parameters. The CCN properties that are sought are the C and k parameters in the N = CSk relationship, although activation spectra based on the lognormal distribution of particles is also straightforward. Cloud droplet concentration at cloud base is retrieved from a Doppler cloud radar combined with a microwave radiometer following a previously published technique. Cloud base is determined from a lidar or ceilometer. Vertical velocity just above cloud base is determined from the vertically pointing Doppler cloud radar. By combining the simultaneous retrievals of drop number and vertical velocity, and assuming theoretical relationships between these parameters and the subcloud aerosol parameters, the C parameter can be derived, under the assumption of a fixed k. If a calibrated backscatter lidar measurement is available, retrieval of both C and k parameters is possible. The retrieval is demonstrated for a dataset acquired during the Atlantic Stratocumulus Transition Experiment using a least squares minimization technique. Sensitivity to assumptions used in the retrieval is investigated. It is suggested that this technique may afford the acquisition of long-term datasets for climate monitoring purposes. Further investigation with focused experiments designed to address the issue more rigorously is required."
"7005814217;","Analysis of the improvement in implied meridional ocean energy transport as simulated by the NCAR CCM3",1998,"10.1175/1520-0442(1998)011<1237:AOTIII>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031667829&doi=10.1175%2f1520-0442%281998%29011%3c1237%3aAOTIII%3e2.0.CO%3b2&partnerID=40&md5=232114634cfebc661934192f677efe97","The implied meridional ocean energy transport diagnosed from uncoupled integrations of two atmospheric general circulation models-the National Center for Atmospheric Research Community Climate Model versions 2 and 3 (CCM2 and CCM3)-shows radically different transport characteristics throughout much of the Southern Hemisphere. The CCM2 simulation requires an equatorward transport of energy by the oceans, and the CCM3 exhibits a poleward energy transport requirement, very similar to what is derived from observational analyses. Previous studies have suggested that errors in the implied ocean energy transport are largely attributable to errors in the simulated cloud radiative forcing. The results of this analysis show that although the proper simulation of the radiative effects of clouds is likely to be a necessary condition for realistic meridional ocean energy transport, it is not sufficient. Important changes in the CCM3 equatorial surface latent heat fluxes, associated with a deep formulation for parameterized moist convection, are primarily responsible for the improved ocean energy transport, where this change in the surface energy budget is much more weakly reflected in top-of-atmosphere differences in cloud radiative forcing."
"7006550762;7004214645;7005117153;7004238859;","Climate change and the middle atmosphere. Part III: the doubled CO2 climate revisited",1998,"10.1175/1520-0442(1998)011<0876:CCATMA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031671105&doi=10.1175%2f1520-0442%281998%29011%3c0876%3aCCATMA%3e2.0.CO%3b2&partnerID=40&md5=ffaed1794b88b07ad1151bf365154aa9","The response of the troposphere-stratosphere system to doubled atmospheric CO2 is investigated in a series of experiments in which sea surface temperatures are allowed to adjust to radiation imbalances. The Goddard Institute for Space Studies (GISS) Global Climate Middle Atmosphere Model (GCMAM) warms by 5.1°C at the surface while the stratosphere cools by up to 10°C. When ozone is allowed to respond photochemically, the stratospheric cooling is reduced by 20%, with little effect in the troposphere. Planetary wave energy increases in the stratosphere, producing dynamical warming at high latitudes, in agreement with previous GCMAM doubled CO2 simulations; the effect is due to increased tropospheric generation and altered refraction, both strongly influenced by the magnitude of warming in the model's tropical upper troposphere. This warming also results in stronger zonal winds in the lower stratosphere, which appears to reduce stratospheric planetary wave 2 energy and stratospheric warming events. The dynamical changes in the lower stratosphere are weakened when O3 chemistry on polar stratospheric cloud effects are included at current stratospheric chlorine levels. Comparision with the nine-level version of the GISS GCM with a top at 10 mb shows that both the stratospheric and tropospheric dynamical responses are different. The tropospheric effect is mostly a function of the vertical resolution in the troposphere; finer vertical resolution leads to increased latent heat release in the warmer climate, greater zonal available potential energy increase, and greater planetary longwave energy and energy transports. The increase in planetary longwave energy and residual circulation in the stratosphere is reproduced when the model top is lifted from 30 to 50 km, which also affects upper-tropospheric stability, convection and cloud cover, and climate sensitivity."
"7003279098;6603950324;57206330745;7102015136;","The impact of simulated climate change on the air-sea flux of dimethylsulphide in the subantarctic Southern Ocean",1998,"10.1034/j.1600-0889.1998.t01-3-00006.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032455124&doi=10.1034%2fj.1600-0889.1998.t01-3-00006.x&partnerID=40&md5=76c84d9ea6180403a564ccb72e2649ca","Dimethylsulphide is an important sulphur-containing trace gas produced by enzymatic cleavage of its precursor compound, dimethylsulphoniopropionate (DMSP) which is released by marine phytoplankton in the upper ocean. After ventilation to the atmosphere, DMS is oxidised to form sulphate aerosols which in the unpolluted marine atmosphere are a major source of cloud condensation nuclei (CCN). Because the microphysical properties of clouds relevant to climate change are sensitive to CCN density, it has been postulated that marine sulphur emissions may play a role in climate regulation. Here we examine the DMS cycle in the subantarctic Southern Ocean west of the atmospheric baseline station at Cape Grim, NW Tasmania, where a long time series of atmospheric data has been collected. The Southern Ocean is relatively free of anthropogenic sulphur emissions and thus sulphate aerosols will be mainly due to the biogenic source of DMS. An atmospheric general circulation model has been used to provide meteorological forcings under current and doubled atmospheric CO2 conditions. We have used an existing DMS production model to investigate the sensitivity of the sea-to-air flux to the simulated changes in temperature and wind speed at the ocean surface. Under doubled CO2 conditions sea-surface temperature is simulated to increase by 4°C throughout the year. Annual mean surface wind speed is simulated to decrease by about 3%. The changes in temperature and wind speed cause a net increase of DMS transfer velocity in the range 3-11%. The increase in temperature will also increase the growth rate of phytoplankton. The annual integrated DMS flux is simulated to increase between 2% and 8% under doubled CO2 conditions. A median change of +5% in DMS flux corresponds to an increase in the range 2 to 4% in cloud condensation nuclei (CCN) concentration and a perturbation to radiative forcing of -0.29 W m-2, confirming a minor role for DMS-derived aerosols in climate regulation."
"6701659989;","Sensitivity of Climate Drift to Atmospheric Physical Parameterizations in a Coupled Ocean-Atmosphere General Circulation Model",1998,"10.1175/1520-0442(1998)011<1633:SOCDTA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001041892&doi=10.1175%2f1520-0442%281998%29011%3c1633%3aSOCDTA%3e2.0.CO%3b2&partnerID=40&md5=15f7880d28a361804bd7d2fed0de4492","Sensitivity of climate drift to selected convection and cloudiness parameters is investigated with a coupled ocean-atmosphere general circulation model. The dependence of the coupled model climatology upon parameterizations of convective entrainment and stratocumulus cloud cover is studied. The methodology relies upon short uncoupled (1 yr) and coupled (3 yr) simulations. The coupled model climatology is very sensitive to both parameterizations. For instance, the air-sea interface mean state can be too warm or too cold depending on the profile of the convective entrainment rate. Enhanced entrainment at lower levels breaks the symmetry of the tropical precipitation pattern observed in both forced and coupled control simulations. Furthermore, the zonal wind stress strength and related thermocline slope around 150°W are shown to be crucial in determining the warm pool-cold tongue structure in the tropical Pacific. The model sensitivity is found to be the result of complex feedbacks between convection, cloud, and boundary layer processes, sea surface temperature (SST), and large-scale ocean-atmosphere dynamics."
"6507785198;6701573579;","The evaporation of precipitation and its geographical distribution",1998,"10.1016/S0079-1946(98)00043-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031719151&doi=10.1016%2fS0079-1946%2898%2900043-3&partnerID=40&md5=4625209c29d7cb8dbace2c400b4be8a8","In order to estimate the evaporation of precipitation in different climate regions, as a first attempt, climate data from four meteorological stations have been used for mean daily precipitation, mean seasonal surface temperature and surface humidity and combined with mean seasonal vertical temperature profiles. Since the profiles are not representative for days with precipitation the results are preliminary and have to be interpreted with some caution. Nevertheless the following conclusions seem to be justified. The least evaporation - as well in absolute as in relative terms compared to the amount of precipitation produced in clouds - takes place in the humid tropics, where high humidity and low clouds prevail and also the most intense daily rain rate at the ground is observed. The calculations indicate that here the highest production of annual precipitation takes place above the cloud base. Evaporation of rain is limited to the levels just above the ground. The highest mean rain rate at the cloud base, however, seems to occur in the subtropics, where storms are rare but intense. Very dry environmental low-level air is responsible for the greatest average height of the cloud base and the most intense evaporation rate, which takes place at the highest possible level halfway between cloud base and ground. The high mean rain intensity computed at the cloud base is drastically reduced by evaporation, thus the observed mean daily rain rate on the ground ranks only on second place. In the midlatitudes precipitation is almost as frequent as in the tropics but the rates are lower, therefore the total annual observed precipitation is also much lower but still ranks on second place. The precipitation rate at the cloud base and the average cloud level do not indicate a great seasonal variation. The total annual precipitation produced in clouds is found to rank on the last place, with about 50% more rain being produced in the summer than snow in the winter, as also the number of days with precipitation is somewhat more frequent in the summer. The results suggest that probably about 60% or more of the precipitation produced in clouds also arrives at the ground. In contrast to the midlatitudes the subarctic shows a significant seasonal variation. Here the greatest number of days with precipitation is observed. The highest frequency of precipitation occurs during winter, when frequent cyclonic activity causes long lasting continuous precipitation. Both seasons contribute about equal amounts to the total annual precipitation, despite the longer duration of the winter season, as the summerly rain rate at the ground exceeds the intensity of snow falls. At the cloud base, however, the precipitation on a winter day seems to exceed the daily production of rain in the summer by almost 100%. Our results suggest a significant difference in the height of the cloud base between summer and winter. During the winter season the cloud base is found at a rather high level. The humidity profile, which should be fairly reliable because of the high frequency of days with precipitation, indicates a high reaching moist but unsaturated layer in which considerable evaporation of snow seems to take place. Actually this result was expected and it is suggested that in arctic and subarctic regions the reduction of precipitation due to evaporation in the subcloud layer is substantial, at least in a relative sense, as during winter the fraction of precipitation generated in clouds, which evaporates, is comparable with the evaporation of rain in the subtropics. As a consequence in the subarctic probably not much less precipitation is produced in clouds than in the tropics, with more than three times as much snow leaving the cloud base as rain, mainly because of prevailing cyclonic conditions during winter time."
"7103373860;7005626683;7005743827;7102634174;55390187500;7006454865;7401829435;","An Atmospheric Radiation and Cloud Station in the Tropical Western Pacific",1998,"10.1175/1520-0477(1998)079<0627:AARACS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031669880&doi=10.1175%2f1520-0477%281998%29079%3c0627%3aAARACS%3e2.0.CO%3b2&partnerID=40&md5=f39e0fc16e8c76d55683a91cfa44db4c","The interaction of clouds and radiation is a particularly difficult issue in the study of climate change. Clouds have a large impact on the earth's radiation budget but the range of spatial and temporal scales and the complexity of the physical processes associated with clouds made these interactions difficult to simulate. The Department of Energy's Atmospheric Radiation Measurement (ARM) program was established to improve the understanding of the interaction of radiation with the atmosphere with a particular emphasis on the effects of clouds. To continue its role of providing data for the study of these interactions, the ARM program deployed an Atmospheric Radiation and Cloud Station (ARCS) in the tropical western Pacific. This site began operation in October 1996. The tropical western Pacific is a very important climatic region. It is characterized by strong solar heating, high water vapor concentrations, and active convection. The ARCS is equipped with a comprehensive suite of instruments for measuring surface radiation fluxes and properties of the atmospheric state and is intended to operate for the next 10 years. The ARCS is an integrated unit that includes a data management system, a site monitor and control system, an external communications system, redundant electrical power systems, and containers that provide shelter for the equipment as well as work space for site operators, technicians, and visiting scientists. The dataset the ARCS produces will be invaluable in studying issues related to clouds and radiation in the Tropics. The site is located in Manus Province, Papua New Guinea, at 2.060°S, 147.425°E, 300 km north of the island of New Guinea. Two more ARCS are planned for deployment across the tropical Pacific."
"35494005000;","Cirrus layer microphysical properties derived from surface-based millimeter radar and infrared interferometer data",1998,"10.1029/98JD02117","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573004&doi=10.1029%2f98JD02117&partnerID=40&md5=db807cd101189465332516ae4ad87926","Observational data regarding the properties of cirrus clouds are needed to aid in the development of accurate, physically based parameterizations in climate models. The Atmospheric Radiation Measurement (ARM) program, sponsored by the U.S. Department of Energy, is providing continuous observations of cirrus clouds with a suite of instrumentation at several locales. In this paper, we describe an algorithm to derive the microphysical properties of optically thin cirrus clouds. This algorithm uses radar reflectivity and infrared emission spectra from an interferometer and is tailored for the specific instruments at the ARM sites. We present in situ validation of the technique and examine a cirrus case study to illustrate the sensitivity of the algorithm. In the case study, solar fluxes calculated from the retrieved microphysical parameters are compared to observed fluxes to build confidence in the algorithm results. Comparison of the retrieved quantities to microphysical parameters retrieved from satellite data is also presented. Copyright 1998 by the American Geophysical Union."
"6602386862;6602984400;6603632722;35586230700;6602809715;8767728300;","Atmospheric and oceanic evidences of El Nino-Southern Oscillation events in the south central Pacific Ocean from coral stable isotopic records over the last 137 years",1998,"10.1029/98PA02502","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032417634&doi=10.1029%2f98PA02502&partnerID=40&md5=416478bf9ad068ee1d5c52ffbb737d65","We measured δ18O and δ13C in Porites lutea collected in the Moorea lagoon where the instrumental records show that an El Nino-Southern Oscillation (ENSO) event implies both a cloud cover decrease and a weak sea surface temperature (SST) increase. Two proxies allow an ENSO record to be reconstructed at Moorea: the annual δ13C anomaly, associated with the South Pacific Convergence Zone motion, and an annual δ18O anomaly showing increased SST. The frequency bands exhibited by the singular spectral analysis (SSA) and the multitaper method of the annual δ18O and δ13C records are centered on 2.5 and 5.2 years and 2.4 and 3.2 years, respectively, which are the main ENSO modes. We used SSA to reconstruct ENSO events at Moorea over the past 137 years. Results indicate that climate variability at this site is strongly affected by ENSO events."
"36720598100;7003833060;","Are there real interdecadal variations in marine low clouds?",1998,"10.1175/1520-0442(1998)011<2910:ATRIVI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032214458&doi=10.1175%2f1520-0442%281998%29011%3c2910%3aATRIVI%3e2.0.CO%3b2&partnerID=40&md5=7b9eb32ea279ab8b441c43919491f573","The dominant interdecadal signal in normalized frequency of occurrence of cumulonimbus reported by volunteer observing ships is globally uniform over the period 1952-92 over all ocean areas between 40°S and 50°N. Globally uniform signals in both normalized frequency of occurrence and amount-when-present also dominate interdecadal variations for other low cloud types. This pattern is inconsistent with plausible physical mechanisms and is apparently due to slow changes in observational practice. Eight ocean weather ships with approximately fixed positions also reported gradual changes in low cloud occurrence frequencies between 1952 and 1969 that were similar in pattern for all eight ships, but for most cloud types these variation patterns differed markedly from those at nearly collocated volunteer observing ships. These apparently spurious variations make it difficult to identify real interdecadal variations in marine clouds from ship observations. However, over the tropical Indian Ocean and central and eastern Pacific Ocean, small but widespread decreases in stratocumulus frequency and increases in deep convective cloud frequency between 1955 and 1978, and 1979 and 1991 tend to be consistently related to changes in sea surface temperature and are likely to be real. Over the western Pacific Ocean, ship reports indicate an increase in the frequency of deep convective clouds between these two periods that is not consistently related to SST changes and is less likely to be real.The dominant interdecadal signal in normalized frequency of occurrence of cumulonimbus reported by volunteer observing ships is globally uniform over the period 1952-92 over all ocean areas between 40°S and 50°N. Globally uniform signals in both normalized frequency of occurrence and amount-when-present also dominate interdecadal variations for other low cloud types. This pattern is inconsistent with plausible physical mechanisms and is apparently due to slow changes in observational practice. Eight ocean weather ships with approximately fixed positions also reported gradual changes in low cloud occurrence frequencies between 1952 and 1969 that were similar in pattern for all eight ships, but for most cloud types these variation patterns differed markedly from those at nearly collocated volunteer observing ships. These apparently spurious variations make it difficult to identify real interdecadal variations in marine clouds from ship observations. However, over the tropical Indian Ocean and central and eastern Pacific Ocean, small but widespread decreases in stratocumulus frequency and increases in deep convective cloud frequency between 1955 and 1978, arid 1979 and 1991 tend to be consistently related to changes in sea surface temperature and are likely to be real. Over the western Pacific Ocean, ship reports indicate an increase in the frequency of deep convective clouds between these two periods that is not consistently related to SST changes and is less likely to be real."
"7005513582;7005814217;7005387356;","The energy budget of the NCAR Community Climate Model: CCM3",1998,"10.1175/1520-0442(1998)011<1151:TEBOTN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031663904&doi=10.1175%2f1520-0442%281998%29011%3c1151%3aTEBOTN%3e2.0.CO%3b2&partnerID=40&md5=2b0b91234b8e5412bd2bceebd4cf45ac","The energy budget of the latest version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM3) is described. The energy budget at the top of the atmosphere and at the earth's surface is compared to observational estimates. The annual mean, seasonal mean, and seasonal cycle of the energy budget are evaluated in comparison with earth radiation budget data at the top of the atmosphere and with the NCAR Ocean Model (NCOM) forcing data at the ocean's surface. Individual terms in the energy budget are discussed. The transient response of the top-of-atmosphere radiative budget to anomalies in tropical sea surface temperature is also presented. In general, the CCM3 is in excellent agreement with ERBE data in terms of annual and seasonal means. The seasonal cycle of the top-of-atmosphere radiation budget is also in good (&lt;10 W m-2) agreement with ERBE data. At the surface, the model shortwave flux over the oceans is too large compared to data obtained by W.G. Large and colleagues (~20-30 W m-2). It is argued that this bias is related to a model underestimate of shortwave cloud absorption. The major biases in the model are related to the position of deep convection in the tropical Pacific, summertime convective activity over land regions, and the model's inability to realistically represent marine stratus and stratocumulus clouds. Despite these deficiencies, the model's implied ocean heat transport is in very good agreement with the explicit ocean heat transport of the NCOM uncoupled simulations. This result is a major reason for the success of the NCAR Climate System Model."
"7201692406;56261301800;6701679469;55465328800;6701857226;7202637955;","Monitoring the Antarctic mesopause region for signatures of climate change",1998,"10.3189/1998aog27-1-669-673","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032409612&doi=10.3189%2f1998aog27-1-669-673&partnerID=40&md5=96f89469dcd43400d9616600954817c6","The polar mesopause region (80-100 km) is the coldest region of the Earth's atmosphere and is expected to be sensitive to global change. Reported increases in observations of polar mesospheric clouds over the last 100 years have been postulated to be related to decreased temperatures (associated with tropospheric warming) and increased water vapour at mesospheric altitudes (a result of increased methane concentrations in the troposphere). The temperature of this region can be monitored by spectroscopic techniques utilising hydroxyl (OH) emissions which originate near 87 km. The Australian Antarctic Division, Atmospheric and Space Physics group has been analyzing OH (6-2) band spectra recorded with a Czerny-Turner scanning spectrometer at Davis Station, Antarctica (68.6°S, 78.0°E) to optimise temperature determinations for climate change studies. A number of difficulties were encountered, some of which have been overcome and all of which can be overcome. The mid-winter average temperature of the OH layer for May-July 1990 has been measured as 224±2 K. The equivalent value for 1996 is 215±2 K. Possible reasons for the difference are discussed."
"7402215419;7201572915;7005729142;7003717604;","Modeling of submillimeter passive remote sensing of cirrus clouds",1998,"10.1175/1520-0450(1998)037<0184:MOSPRS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032004312&doi=10.1175%2f1520-0450%281998%29037%3c0184%3aMOSPRS%3e2.0.CO%3b2&partnerID=40&md5=016cfe616e4ef9df84f364c233801f9d","The scattering properties of cirrus clouds at submillimeter-wave frequencies are analyzed and characterized in this paper. This study lays a theoretical foundation for using radiometric measurements to investigate and monitor cirrus properties from high-flying aircraft or satellite. The significance of this capability is that it would provide data on the global distribution of cloud ice mass that is currently required to validate climate models. At present, these needs remain unmet by existing and planned observational systems. In this study the brightness temperature depression (ΔTb) of upwelling radiation due to cirrus clouds is simulated at 150, 220, 340, 500, 630, and 880 GHz. The effects of a range of size distributions, eight ice particle shapes, and different atmospheric profiles are modeled. The atmospheric transmission is high enough in the submillimeter windows to allow upper-tropospheric sensing from space, but absorption by water vapor reduces the sensitivity to lower cirrus clouds in a simply predictable manner. It is shown that frequencies above 500 GHz have adequate sensitivity to measure cirrus cloud properties. For these higher frequencies, the ΔTb is closely proportional to ice water path (IWP) for median mass equivalent sphere diameters (Dme) above 125 μm. The differing sensitivity with frequency allows two channels to determine particle size. A two-channel Bayesian algorithm is developed to assess retrieval accuracy with a Monte Carlo error analysis procedure. Particle shape, size distribution width, and receiver noise are considered as error sources. The rms errors for a nadir view with 630/880 GHz are less than 40% for IWP &gt; 5 g m-2 and Dme &gt; 100 μm, while using an oblique viewing angle of 73° results in the same accuracy down to an IWP of 1 g m-2 (visible optical depth less than 0.1). The two-channel algorithm and error analysis methods are used to show how submillimeter radiometer and millimeter radar measurements may be combined."
"7402612084;57206416522;","A flexible climate model for use in integrated assessments",1998,"10.1007/s003820050224","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031846054&doi=10.1007%2fs003820050224&partnerID=40&md5=ceab4084574c3a274e500a357a0c4be9","Because of significant uncertainty in the behavior of the climate system, evaluations of the possible impact of an increase in greenhouse gas concentrations in the atmosphere require a large number of long-term climate simulations. Studies of this kind are impossible to carry out with coupled atmosphere ocean general circulation models (AOGCMs) because of their tremendous computer resource requirements. Here we describe a two dimensional (zonally averaged) atmospheric model coupled with a diffusive ocean model developed for use in the integrated framework of the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change. The 2-D model has been developed from the Goddard Institute for Space Studies (GISS) GCM and includes parametrizations of all the main physical processes. This allows it to reproduce many of the nonlinear interactions occurring in simulations with GCMs. Comparisons of the results of present-day climate simulations with observations show that the model reasonably reproduces the main features of the zonally averaged atmospheric structure and circulation. The model's sensitivity can be varied by changing the magnitude of an inserted additional cloud feedback. Equilibrium responses of different versions of the 2-D model to an instantaneous doubling of atmospheric CO2 are compared with results of similar simulations with different AGCMs. It is shown that the additional cloud feedback does not lead to any physically inconsistent results. On the contrary, changes in climate variables such as precipitation and evaporation, and their dependencies on surface warming produced by different versions of the MIT 2-D model are similar to those shown by GCMs. By choosing appropriate values of the deep ocean diffusion coefficients, the transient behavior of different AOGCMs can be matched in simulations with the 2-D model, with a unique choice of diffusion coefficients allowing one to match the performance of a given AOGCM for a variety of transient forcing scenarios. Both surface warming and sea level rise due to thermal expansion of the deep ocean in response to a gradually increasing forcing are reasonably reproduced on time scales of 100-150 y. However a wide range of diffusion coefficients is needed to match the behavior of different AOGCMs. We use results of simulations with the 2-D model to show that the impact on climate change of the implied uncertainty in the rate of heat penetration into the deep ocean is comparable with that of other significant uncertainties."
"6603451961;7005634455;","Polar radiation budgets of the NCAR CCM3",1998,"10.1175/1520-0442(1998)011<1246:PRBOTN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031667830&doi=10.1175%2f1520-0442%281998%29011%3c1246%3aPRBOTN%3e2.0.CO%3b2&partnerID=40&md5=698c2e5bf3baa9c9d7366349728e8c6f","Present-day Arctic and Antarctic radiation budgets of the National Center for Atmospheric Research Community Climate Model version 3 (CCM3) are presented. The CCM3 simulation is from a prescribed and inter-annually varying sea surface temperature integration from January 1979 through August 1993. Earth Radiation Budget Experiment (ERBE) data from 1985 through 1989 are used for validation of top-of-atmosphere (TOA) absorbed shortwave radiation (ASR) and outgoing longwave radiation (OLR). Summer ASR in both polar regions is less than the observations by about 20 W m-2. While the annual mean OLR in both polar regions is only 2-3 W m-2 less than the ERBE data, the seasonal amplitude in OLR of 40 W m-2 is smaller than the observed of 55-60 W m-2. The annual polar TOA radiation balance is smaller than observations by 5-10 W m-2. Compared to selected model and observational surface data, downward shortwave (SW) is too small by 50-70 W m-2 and downward longwave (LW) too large by 10-30 W m-2. Surface downward LW in clear atmospheres is too small by 10-20 W m-2. The absence of sea-ice melt ponds results in 10-20 W m-2 too much SW absorption during early summer and from 20 to 40 W m-2 too little during late summer. Summer cloud covers are reasonably well simulated, but winter low cloud cover is too high by 0.5-0.7 compared to surface cloud observations. Comparison with limited satellite and in situ observations indicates cloud water path (CWP) is too high by about a factor of 2. While cloud particle sizes are approximately in the range of observed values, regional variation between maritime and continental droplet sizes is too strong over coastlines. Despite several improvements in CCM3 radiation physics, the accuracy of polar TOA annual radiation balance is degraded against the ERBE data compared to CCM2. Improvement in CCM3 polar radiation budgets will require improved simulation of CWP, clear sky LW, and sea ice albedo."
"7801356574;","Influence of air mass history on black carbon concentrations and regional climate forcing in southeastern United States",1998,"10.1029/98JD02475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573003&doi=10.1029%2f98JD02475&partnerID=40&md5=b3dca912d61bfc7b80345f488567e712","Atmospheric black carbon (BC) mass concentrations in the southeastern United States have been measured at a regionally representative site near Mount Mitchell, North Carolina (35°44′05°N, 82°17′15″W, 2038 m elevation), the highest peak in the eastern United States, during a 9 month period from June to October 1996 and March to June 1997. BC concentrations are measured by an aethalometer, which operates by measuring the attenuation of light through a sample. All measured BC concentrations are reported in terms of air mass histories determined from back trajectory analysis using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HY-SPLIT) model. Air masses influencing the site have been classified as polluted, marine, and continental according to SOx, and NOx. emission inventories. The average BC mass concentrations for each sector are 216.6 ± 47.8 ng m-3 for polluted air masses, 65.6 ± 23.5 ng m-3 for marine air masses, and 169.9 ± 50.6 ng m-3 for continental air masses. A positive relationship between cloud condensation nuclei and BC concentrations suggest at times the BC measured at the site may be internally mixed. The average BC concentration found, in cloud water is 74.2 μg kg-1. Derived BC to sulfate mass ratios ranged from 0.01 to 0.06. Copyright 1998 by the American Geophysical Union."
"7004159166;7005219614;9332405800;","Simulation of global sulfate distribution and the influence of effective cloud drop radii with a coupled photochemistry-sulfur cycle model",1998,"10.1034/j.1600-0889.1998.t01-2-00002.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031719880&doi=10.1034%2fj.1600-0889.1998.t01-2-00002.x&partnerID=40&md5=151226432544a952226fd79aad2cb3cc","A sulfur cycle model is coupled to a global chemistry-climate model. The simulated surface sulfate concentrations are generally within a factor of 2 of observed concentrations, and display a realistic seasonality for most background locations. However, the model tends to underestimate sulfate and overestimate surface SO2 at relatively polluted locations. A possible explanation for this is that additional oxidation reactions not considered in the model, may be important. Calculated tropospheric sulfate column abundances exceed those of previous studies, which is predominantly associated with a less efficient nucleation scavenging in wet convective updrafts. Through the simultaneous calculation of the sulfur cycle and tropospheric photochemistry, simulated H2O2 and SO2 concentrations are strongly linked, especially in polluted areas. The coupled model simulates a stronger oxidant limitation and, consequently, a smaller contribution to sulfate formation by H2O2 oxidation of SO2 when compared to sulfur cycle models that use monthly averaged oxidant distributions as input. In the polluted NH, the differences in calculated sulfate columns are largest in winter and relatively small in summer. Therefore, the coupling between the sulfur cycle and the oxidant chemistry is expected to have a minor impact on the calculation of the indirect and direct radiative forcing by sulfate. An empirical relation between sulfate concentration and cloud drop number concentration, derived from cloud measurements at Grean Dun Fell (UK), is applied to the simulated cloud and sulfate fields to derive distributions of effective could drop radii. Additionally, a relation between wind speed and cloud drop number concentration is applied over marine regions to account for the effect of seasalt aerosol on cloud formation when sulfate concentrations are relatively low. Calculated droplet radii are systematically underestimated by about 10-20% in the NH compared to satellite derived values, but they agree relatively well in the SH."
"7005814217;7005513582;7005387356;","The hydrologic and thermodynamic characteristics of the NCAR CCM3",1998,"10.1175/1520-0442(1998)011<1179:THATCO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031661950&doi=10.1175%2f1520-0442%281998%29011%3c1179%3aTHATCO%3e2.0.CO%3b2&partnerID=40&md5=0c80216c0e0f8dfe47afcde9d56f4a6e","Climatological properties for selected aspects of the thermodynamic structure and hydrologic cycle are presented from a 15 yr numerical simulation conducted with the National Center for Atmospheric Research Community Climate Model, version 3 (CCM3), using an observed sea surface temperature climatology. In most regards, the simulated thermal structure and hydrologic cycle represent a marked improvement when compared with earlier versions of the CCM. Three major modifications to parameterized physics are primarily responsible for the more notable improvements in the simulation: modifications to the diagnosis of cloud optical properties, modifications to the diagnosis of boundary layer processes, and the incorporation of a penetrative formulation for deep cumulus convection. The various roles of these physical parameterization changes will be discussed in the context of the simulation strengths and weaknesses."
"6701387222;11440653000;7402899368;","A parameterization of radiative fluxes suitable for use in a statistical-dynamical model",1998,"10.1007/BF01025181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0040757478&doi=10.1007%2fBF01025181&partnerID=40&md5=c87d2e12e9855531f1ee89c3463b7b5c","A parameterization of shortwave and longwave radiation fluxes derived from detailed radiative transfer models is included in a global primitive equation statistical-dynamical model (SDM) with two hulk atmospheric layers. The model is validated comparing the model simulations with the observed mean annual and seasonal zonally averaged climate. The results show that the simulation of the shortwave and longwave radiation fluxes matches well with the observations. The SDM variables such as surface and 500hPa temperatures, zonal winds at 250hPa and 750hPa, vertical velocity at 500hPa and precipitation are also in good agreement with the observations. A comparison between the results obtained with the present SDM and those with the previous version of the model indicates that the model results improved when the parameterization of the radiative fluxes based on detailed radiative transfer models are included into the SDM. The SDM is used to investigate its response to the greenhouse effect. Sensitivity experiments regarding the doubling of CO2 and the changing of the cloud amount and height are performed. In the case 2×CO2 the model results are consistent with those obtained from GCMs, showing a warming of the climate system. An enhancement of the greenhouse effect is also noted when the cloud layer is higher. However, an increase of the cloud amount in all the latitude belts provokes an increase of the surface temperature near poles and a decrease in all the other regions. This suggests that the greenhouse effect overcomes the albedo effect in the polar latitudes and the opposite occurs in other regions. In all the experiments the changes in the surface temperature are larger near poles, mainly in the Southern Hemisphere."
"7003455444;16637291100;57153656200;7005311892;57206225739;","A new monthly climatology of global radiation for the arctic and comparisons with NCEP-NCAR reanalysis and ISCCP-C2 fields",1998,"10.1175/1520-0442(1998)011<0121:ANMCOG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032004181&doi=10.1175%2f1520-0442%281998%29011%3c0121%3aANMCOG%3e2.0.CO%3b2&partnerID=40&md5=30749c84d399f40b9fc294ccdc3c7721","Measurements from the Russian ""North Pole"" series of drifting stations, the United States drifting stations ""T-3"" and ""Arlis II,"" land stations, and, where necessary, over the northern North Atlantic and coastal Greenland, empirically derived values from earlier Russian studies are used to compile a new gridded monthly climatology of global (downwelling shortwave) radiation for the region north of 65° N. Spatio-temporal patterns of fluxes and effective cloud transmittance are examined and comparisons are made with fields from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis and those derived from the International Satellite Cloud Climatology Project (ISCCP) C2 (monthly) cloud product. All months examined (March-October) show peak fluxes over the Greenland ice sheet. March, September, and October feature a strong zonal component. Other months exhibit an asymmetric pattern related to cloud fraction and optical depth, manifested by an Atlantic side flux minimum. For June, the month of maximum insolation, fluxes increase from less than 200 W m-2 in the Norwegian and Barents seas to more than 300 W m-2 over the Pacific side of central Arctic Ocean extending into the Beaufort Sea. June fluxes of more than 340 W m-2 are found over the Greenland ice sheet. Effective cloud transmittance, taken as the ratio of the observed flux to the modeled clear sky flux, is examined for April-September. Values for the Atlantic sector range from 0.50-0.60, contrasting with the central Arctic Ocean where values peak in April at 0.75-0.80, falling to 0.60-0.65 during late summer and early autumn. A relative Beaufort Sea maximum is well expressed during June. The NCEP-NCAR and ISCCP products capture 50%-60% of the observed spatial variance in global radiation during most months. However, the NCEP-NCAR fluxes are consistently high, with Arctic Ocean errors in excess of 60 W m-2 during summer, reflecting problems in modeled cloud cover. ISCCP fluxes compare better in terms of magnitude."
"35464731600;16185051500;7006146408;7004864963;7004174939;7005399437;35468686100;35466821900;7003741536;6603785227;7005200001;7004027377;7005981420;35203432500;7404597424;7103056277;7005135473;7101899854;","Smoke, Clouds, and Radiation-Brazil (SCAR-B) experiment",1998,"10.1029/98JD02281","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573699&doi=10.1029%2f98JD02281&partnerID=40&md5=f6eb00c30d924b741bd236a763247c8c","The Smoke, Clouds, and Radiation-Brazil (SCAR-B) field project took place in the Brazilian Amazon and cerrado regions in August-September 1995 as a collaboration between Brazilian and American scientists. SCAR-B, a comprehensive experiment to study biomass burning, emphasized measurements of surface biomass, fires, smoke aerosol and trace gases, clouds, and radiation, their climatic effects, and remote sensing from aircraft and satellites. It included aircraft and ground-based in situ measurements of smoke emission factors and the compositions, sizes, and optical properties of the smoke particles; studies of the formation of ozone; the transport and evolution of smoke; and smoke interactions with water vapor and clouds. This overview paper introduces SCAR-B and summarizes some of the main results obtained so far. (1) Fires: measurements of the size distribution of fires, using the 50 m resolution MODIS Airborne Simulator, show that most of the fires are small (e.g., 0.005 km2), but the satellite sensors (e.g., AVHRR and MODIS with 1 km resolution) can detect fires in Brazil which are responsible for 60-85% of the burned biomass; (2) Aerosol: smoke particles emitted from fires increase their radius by as much as 60% during their first three days in the atmosphere due to condensation and coagulation, reaching a mass median radius of 0.13-0.17 μm; (3) Radiative forcing: estimates of the globally averaged direct radiative forcing due to smoke worldwide, based on the properties of smoke measured in SCAR-B (-0.1 to -0.3 W m-2), are smaller than previously modeled due to a lower single-scattering albedo (0.8 to 0.9), smaller scattering efficiency (3 m2 g-1 at 550 nm), and low humidification factor; and (4) Effect on clouds: a good relationship was found between cloud condensation nuclei and smoke volume concentrations, thus an increase in the smoke emission is expected to affect cloud properties. In SCAR-B, new techniques were developed for deriving the absorption and refractive index of smoke from ground-based remote sensing. Future spaceborne radiometers (e.g., MODIS on the Earth Observing System), simulated on aircraft, proved to be very useful for monitoring smoke properties, surface properties, and the impacts of smoke on radiation and climate. Copyright 1998 by the American Geophysical Union."
"7404416268;7203062127;","Arctic cloud-radiation-temperature associations in observational data and atmospheric reanalyses",1998,"10.1175/1520-0442(1998)011<3030:ACRTAI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032216180&doi=10.1175%2f1520-0442%281998%29011%3c3030%3aACRTAI%3e2.0.CO%3b2&partnerID=40&md5=50e10dfa6360f7b75556813ca4252518","Associations between cloudiness, radiative fluxes, and surface air temperature in the central Arctic are evaluated from 1) measurements made at Russian drifting ice stations, and 2) atmospheric reanalyses of the National Centers for Environmental Prediction (NCEP) and the European Centre for Medium-Range Weather Forecasts (ECMWF). In the ice station data, cloudiness is associated with an increase of downward longwave radiation in all months and an increase of net (downward minus upward) total radiation from September through March. The surface air temperatures under overcast skies are 6°-9°C higher than under clear skies during September-March, and the differences are even larger when the observations are stratified by wind as well as cloudiness. The warming by the radiative flux enhancement after a transition from clear skies to overcast has a 1 -2-day timescale, while the cooling after the transition to clear skies has a somewhat shorter timescale. The NCEP reanalysis exaggerates slightly the association between cloudiness and surface air temperature, while the ECMWF reanalysis shows a considerably weaker association. The maximum cloud-radiative forcing (MCRF), defined as the difference between the ice station measurements of net surface radiation under cloudy and clear skies, ranges from -59 W m-2 in June to positive values of 20-30 W m-2 in September-March. The annual mean is small but positive, 3 W m-2, despite the approximately three-month summer period of substantially negative MCRF. These findings are consistent with the conventional cloud-radiative forcing obtained in earlier studies using satellite data and one-dimensional models of the Arctic atmosphere and sea ice. Neither reanalysis captures the seasonality of the observationally deduced effects of clouds on surface radiation. The NCEP reanalysis does not capture the seasonality of the actual cloudiness (as defined by the reported cloud fractions), while the ECMWF reanalysis does not show an impact of clouds on the surface solar flux. Issues needing further attention in the model-data comparison are the effects of surface heterogeneities, the characterization of Arctic clouds, the formulational reasons for the discrepancies between the model-derived reanalyses and the observational data, and the implications for model-derived projections of climate change in the Arctic.Associations between cloudiness, radiative fluxes, and surface air temperature in the central Arctic are evaluated from 1) measurements made at Russian drifting ice stations, and 2) atmospheric reanalyses of the National Centers for Environmental Prediction (NCEP) and European Centre for Medium-Range Weather Forecasts (ECMWF). In the ice station data, cloudiness is associated with an increase of downward longwave radiation in all months and an increase of net total radiation from September through March. The maximal cloud-radiative forcing (MCRF), defined as difference between the ice station measurements of net surface radiation under cloudy and clear skies, ranges from -59 Wm-2 in June to positive values of 20-30 Wm-2 in September-March. The annual mean is small but positive, 3 Wm-2, despite the approximately three-month summer period of substantially negative MCRF."
"7006246996;7202081862;7004303568;","Global surface ultraviolet radiation climatology from TOMS and ERBE data",1998,"10.1029/98JD02308","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573269&doi=10.1029%2f98JD02308&partnerID=40&md5=81ff3880b9ee33318ade7ebec9306afa","A global climatology of biologically active solar ultraviolet radiation (UVR) at the Earth's surface is derived using NASA total ozone mapping spectrometer (TOMS) measurements of column ozone abundance and NASA Earth Radiation Budget Experiment (ERBE) measurements of solar reflectance from the Earth-atmosphere system. These two sources of satellite data are used as input to a delta-Eddington radiative transfer model to estimate climatological cloud opacity and thereby demonstrate how surface UVR varies with geography and season. The surface UVR fluxes are spectrally resolved to enable weighted integration with any biological action spectrum. Solar elevation is shown to be more important than total column ozone abundance in governing the variability of surface UVR over large geographic areas, although some regions with pronounced local minima in ozone (30 Dobson units or more) will cause noticeable enhancements of integrated UV-B (280-315 nm) flux relative to UV-A (315-400 nm). The greatest variability in surface UVR within a given climate zone is induced by cloud cover. During summer, regions that show lower surface UVR fluxes relative to their surrounding regions include the eastern United States (versus the western United States), India, China (in the vicinity of the Yangtze River), and Japan (relative to the surrounding oceans). Cloud cover over tropical rainforest areas reduces the surface UVR flux relative to ocean areas at the same latitudes. The UVR cloud transmission derived from the TOMS and ERBE data correlates with an independent climatology of global cloud coverage. The UVR mapping method, based on the TOMS and ERBE data, allows a direct investigation of diurnal variability and a rigorous calculation of the biologically relevant integrated daily dose of UVR. However, it is shown that a UVR mapping method based on TOMS data alone, which is limited to only local noon satellite measurements, can make defensible estimates of the integrated daily UVR dose and the instantaneous local noon UVR surface flux. Copyright 1998 by the American Geophysical Union."
"7004214645;7006550762;7005117153;","Climate change and the middle atmosphere. Part IV: ozone response to doubled CO2",1998,"10.1175/1520-0442(1998)011<0895:CCATMA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031688642&doi=10.1175%2f1520-0442%281998%29011%3c0895%3aCCATMA%3e2.0.CO%3b2&partnerID=40&md5=ebee0f68703db076ec1f120a4581c7bb","Parameterized stratospheric ozone photochemistry has been included in the Goddard Institute for Space Studies (GISS) GCM to investigate the coupling between chemistry and climate change for the doubled CO2 climate. The chemical ozone response is of opposite sign to temperature changes, so that radiative cooling in the upper stratosphere results in increased ozone, while warming reduces ozone in the lower stratosphere. The increased overhead column reduces the amount of UV reaching the lower stratosphere, resulting in further ozone decreases there. Changes of up to 15% are seen, including both photochemistry and transport. Good agreement is found between the authors' results and those in other models for tropical latitudes where the stratospheric temperature responses are similar. However, in the extratropics, there are large differences between present results and those of the other models due to differences in tropospheric warming and tropospheric forcing of the stratospheric residual circulation. A net decrease in column ozone at midlatitudes is seen in this climate model, in contrast to the other models that showed an increase in column ozone everywhere. These ozone reductions lead to an increase of 10% in UV radiation reaching the surface at northern midlatitudes. The authors find significantly less of an increase in the high-latitude ozone column than in the other models. When parameterized heterogeneous chemistry on polar stratospheric clouds is also included, while maintaining current chlorine loading, it is found that the Antarctic ozone hole becomes significantly larger and of longer duration. In addition, an ozone hole of approximately half the depth in percent of the current Antarctic ozone hole forms in the Arctic due to both chemistry and transport changes resulting from a reduction of sudden warmings seen in the doubled CO2 atmosphere."
"7004410351;","Urban effects on precipitation amount",1998,"10.1191/030913398670090480","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032463875&doi=10.1191%2f030913398670090480&partnerID=40&md5=8eeaf416a928f7ac508deae335be05bf","Major reviews of urban effects on local climate, extending from Kratzer in 1937 through to Landsberg in 1981, have dealt primarily with radiation, temperature, wind, and air quality. To a much lesser extent they have examined moisture-related elements including humidity, cloud, precipitation, and storminess. Selecting air temperature to represent the former group and precipitation amount to represent the latter, the author asserts that, because of the intrinsic physical differences between them, there are necessarily important differences in the methods to be used for their proper observation, analysis, presentation, and interpretation pertaining to urban effects. The principal differences are based in the fact that temperature is continuous in both time and space, whereas precipitation is continuous in neither. The author maintains that because of these differences, urban climatologists have had much greater success in specifying and explaining urban effects on temperature than on precipitation amount. Further, he makes the case that, lack of recognition that methods used for the study of urban effects on temperature are too often inappropriate for study of urban effects on precipitation amount, has led to a state of affairs where there remains basic uncertainty about the specification of urban effects on precipitation amount, and even greater uncertainty about their explanation. In making that case, the author includes 1) an historical perspective, 2) a critical evaluation of methods, 3) an overview of the status of urban precipitation climatology, and 4) recommendations concerning future research."
"7005272608;6507981678;","The climate of the kalahari transect",1998,"10.1080/00359199809520380","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0010630619&doi=10.1080%2f00359199809520380&partnerID=40&md5=5cb788217409d0770608475fc1a4128d","The climate of the Kalahari Transect is defined by the nature of the general circulation of the atmosphere over Africa south of the equator and the regional circulation variations that determine local weather. Individual synoptic systems and the transport of moisture into the region by converging and diverging airstreams in both summer and winter govern conditions favouring or inhibiting the major rainfall-producing process of convective precipitation. The climate is illustrated by the spatial variation of moisture, rainfall, temperature, evaporation and other fields. It is shown that the climate of the transect varies from the subtropical in the south to the tropical in the north with characteristic gradients of most parameters between the two regions in both summer and winter. The Kalahari Transect is a multi-disciplinary regional project having as its aim the advancement of the understanding of the effects of human and climatically induced global change over a large area of southern Africa. It has a near-unique advantage of being a study where the underlying regional geology, comprising Kalahari sand, is uniform over a considerable range of latitude. This offers the prospect of reducing the uncertainties associated with regional manifestations of global change. Climate and climatic change remain major determinants of all facets of the Kalahari Transect study. In this paper, the nature of the regional climate of the transect and how it may change in the future are discussed. The Kalahari Transect has a latitudinal extent from 14°S to 28°S and a longitudinal equivalent from 21°E to 28°E. The delimited area covers much of central southern Africa, ranging from shrubland and grassy desert in the south to evergreen dense woodland in the north. The whole region is dominated by the southern hemisphere descending limb of the Hadley cell of the general atmospheric circulation, the southern part of the transect more so than the northern part. This means that anticyclonic circulation patterns are the dominant circulation type for most of the year. The attendant atmospheric conditions are characterised by subsiding, stable air masses, hazy lower tropospheric conditions and generally cloud-free skies. South of the Tropic of Capricorn disturbances in the mid-latitude westerlies assume an increasingly important role in determining rainfall, whereas to the north seasonal migrations of the Inter-Tropical Convergence Zone (ITCZ) become the major determinant of the annual rainfall cycle. Over the whole region cumulus convective activity, enhanced by atmospheric disturbances associated with negative pressure departures and suppressed by those with positive departures, is the major determinant of rainfall, which everywhere exhibits a strong seasonal cycle with a summer maximum. In general, it is difficult to acquire a dense coverage of continuous, long-period, modern meteorological records for Africa south of the Sahara. The same is true of the region covered by the Kalahari transect. Good general descriptions of the climate of the region are provided in the atlases of Jackson (1961) and Thompson (1965). The reviews of Torrance (1972), Schulze (1972, 1984). Hastenrath (1984) and Tyson (1986) provide additional and more up-to-date material. These sources and others have been used to compile a climatology of the Kalahari transect region. After a brief summary of the regional atmospheric circulation, the main parameters to be considered are rainfall, cloud cover, energy budget components, temperature, atmospheric moisture, evaporation and potential evapotranspiration. The summary of the transect climate concludes with estimates of possible future regional conditions that may follow from global greenhouse warming. © 1998 Taylor & Francis Group, LLC. All rights reserved."
"7005513582;","Simulation of the tropical Pacific warm pool with the NCAR climate system model",1998,"10.1175/1520-0442(1998)011<1342:SOTTPW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031663906&doi=10.1175%2f1520-0442%281998%29011%3c1342%3aSOTTPW%3e2.0.CO%3b2&partnerID=40&md5=a48a484e219c0fdb09d00cc9c243cd76","The simulation of the tropical western Pacific warm pool is explored with the NCAR Climate System Model (CSM). The simulated sea surface temperatures in the Pacific basin have biases that are similar to other coupled model simulations in this region. In particular, an excessive cold tongue of water extends across the Pacific basin, with warm water on either side of this cold tongue. The warm pool region is also too cold. This cold bias exists in spite of an overestimate in surface net energy flux into this region. To understand the source of this bias in SST, simulations from the uncoupled and fully coupled models are analyzed in terms of biases in surface energy budget. These analyses suggest that the strong constraint of little ocean heat transport out of the warm pool region forces a change in SST gradient that leads to an increase in the atmospheric zonal wind. This increase in zonal wind causes an increase in latent heat flux in the warm pool region. The increase in latent heat flux is required to offset a significant (~35 W m-2) bias in net surface solar flux. The bias in surface solar flux is due to an underestimate of model cloud shortwave absorption."
"7003376335;7402717381;","The sublimation of falling snow over the Mackenzie River Basin",1998,"10.1016/S0169-8095(98)00084-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032215794&doi=10.1016%2fS0169-8095%2898%2900084-2&partnerID=40&md5=9e9cda2a664c9231cd93db009acb44da","The sublimation of falling snow may be an important component of the atmospheric water budget of the Mackenzie River Basin and many parts of the Arctic. To investigate this issue, a simple sublimation model is used along with surface precipitation observations and sonde data obtained during the autumn 1994 Beaufort and Arctic Storms Experiment (BASE). Model results are then compared with actual precipitation measurements at Inuvik and Tuktoyaktuk, sites in Northern Canada, to approximate mass loss due to sublimation. The sublimation results are found to vary in concert with cloud base height, precipitation intensity aloft and the nature of the precipitation. Atmospheric conditions are furthermore examined over a wide range of the Arctic, especially the Mackenzie River Basin, to assess to what degree the results can be generalized. The presence of a relatively dry near-surface layer, a favourable environment for sublimation, is a key feature of most sites during the early autumn storm period. Estimates of sublimational mass losses are found over Inuvik and Tuktoyaktuk using sonde derived cloud base heights and temperature and humidity profiles. Sublimation losses for such sites are found to be of the order of 40-60%, which shows that sublimation is indeed a significant process over the Mackenzie Basin and needs to be well handled in climate models. However, increasing the vertical resolution of the sublimation model to that of climate scales can dramatically affect predicted sublimation amounts; how to properly account for sublimation then remains a difficult task."
"7005365571;7102663296;6603809220;6701715507;56363371300;","The surface radiation budget over oceans and continents",1998,"10.1175/1520-0442-11.8.1951","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032453920&doi=10.1175%2f1520-0442-11.8.1951&partnerID=40&md5=57fd237a2d298ba4542dc813b1660d38","An updated evaluation of the surface radiation budget in climate models (1994-96 versions; seven datasets available, with and without aerosols) and in two new satellite-based global datasets (with aerosols) is presented. All nine datasets capture the broad mean monthly zonal variations in the flux components and in the net radiation, with maximum differences of some 100 W m-2 occurring in the downwelling fluxes at specific latitudes. Using long-term surface observations, both from land stations and the Pacific warm pool (with typical uncertainties in the annual values varying between ±5 and 20 W m-2), excess net radiation (R(N)) and downwelling shortwave flux density (S(o)↓) are found in all datasets, consistent with results from earlier studies [for global land, excesses of 15%-20% (12 W m-2) in R(N) and about 12% (20 W m-2) in S(o)↓]. For the nine datasets combined, the spread in annual fluxes is significant: for R(N), it is 15 (50) W m-2 over global land (Pacific warm pool) in an observed annual mean of 65 (135) W m-2; for S(o)↓, it is 25 (60) W m-2 over land (warm pool) in an annual mean of 176 (197) W m-2. The effects of aerosols are included in three of the authors' datasets, based on simple aerosol climatologies and assumptions regarding aerosol optical properties. They offer guidance on the broad impact of aerosols on climate, suggesting that the inclusion of aerosols in models would reduce the annual S(o)↓ by 15-20 W m-2 over land and 5-10 W m-2 over the oceans. Model differences in cloud cover contribute to differences in S(o)↓ between datasets; for global land, this is most clearly demonstrated through the effects of cloud cover on the surface shortwave cloud forcing. The tendency for most datasets to underestimate cloudiness, particularly over global land, and possibly to underestimate atmospheric water vapor absorption, probably contributes to the excess downwelling shortwave flux at the surface."
"7004861086;35618134000;","Signatures of a universal spectrum for atmospheric interannual variability in some disparate climatic regimes",1998,"10.1007/BF01030450","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032389404&doi=10.1007%2fBF01030450&partnerID=40&md5=f62807a45fedb3f5c72369b56207a1c1","Atmospheric flows exhibit long-range spatiotemporal correlations manifested as the fractal geometry to the global cloud cover pattern concomitant with inverse power law form for power spectra of temporal fluctuations on all space-time scales ranging from turbulence (centimeters-seconds) to climate (kilometers-years). Long-range spatio-temporal correlations are ubiquitous to dynamical systems in nature and are identified as signatures of self-organized criticality. Standard models in meteorological theory cannot explain satisfactorily the observed self-organized criticality in atmospheric flows. Mathematical models for simulation and prediction of atmospheric flows are non-linear and do not possess analytical solutions. Finite precision computer realizations of nonlinear models give unrealistic solutions because of deterministic chaos, a direct consequence of round-off error growth in iterative numerical computations. Recent studies show that round-off error doubles on an average for each iteration of iterative computations. Round-off error propagates to the main stream computation and gives unrealistic solutions in numerical weather prediction (NWP) and climate models which incorporate thousands of iterative computations in long-term numerical integration schemes. An alternative non-deterministic cell dynamical system model for atmospheric flows described in this paper predicts the observed self-organized criticality as intrinsic to quantumlike mechanics governing flow dynamics. The model provides universal quantification for self-organized criticality in terms of the statistical normal distribution. Model predictions are in agreement with a majority of observed spectra of time series of several standard climatological data sets representative of disparate climatic regimes. Universal spectrum for natural climate variability rules out linear trends. Man-made greenhouse gas related atmospheric warming will result in intensification of natural climate variability, seen immediately in high frequency fluctuations such as QBO and ENSO and even shorter timescales. Model concepts and results of analyses are discussed with reference to possible prediction of climate change."
"7101829066;","The Indonesian Throughflow and the global cliamte system",1998,"10.1175/1520-0442(1998)011<0676:TITATG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031849397&doi=10.1175%2f1520-0442%281998%29011%3c0676%3aTITATG%3e2.0.CO%3b2&partnerID=40&md5=aa48e0238898d654e314a7f678cc898e","The role of the Indonesian Throughflow in the global climate system is investigated with a coupled ocean-atmosphere model by contrasting simulations with realistic throughflow and closed Indonesian passages. The Indonesian Throughflow affects the oceanic circulation and thermocline depth around Australia and in the Indian Ocean as described in previous studies and explained by Sverdrup transports. An open throughflow thereby increases surface temperatures in the eastern Indian ocean, reduces temperatures in the equatorial Pacific, and shifts the warm pool and centers of deep conveciton in the atmosphere to the west. This control on sea surface temperature and deep convection affects atmospheric pressure in the entire Tropics and, via atmospheric teleconnections, in the midlatitudes. As a result, surface wind stress in the entire Tropics changes and meridional and zonal gradients of the tropical thermocline and associated currents increse in the Pacific and decrease in the Indian Ocean. The response includes an acceleration of the equatorial undercurrent in the Pacific, and a deceleration in the Indian Ocean. Thus the Indonesian Throughflow exerts significant control over the global climate in general and the tropical climate in particular. Changes of surface fluxes in the Pacific warm pool region are consistent with the notion that shading by clouds, rather than increases of evaporation, limit highest surface temperatures in the open ocean of the western Pacific. In the marignal seas of the Pacific and in the Indian Ocean no such relationship is found. The feedback of the throughflow transport and its wind forcing is negative and suggests that this interplay cannot excite growing solution or lead to self-sustained oscillations of the ocean-atmosphere system."
"7003406400;7101867299;","Radiative-convective equilibrium in a three-dimensional cloud-ensemble model",1998,"10.1256/smsqj.55012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032413083&doi=10.1256%2fsmsqj.55012&partnerID=40&md5=36909d95742e9c2801c4f05424d642f2","A knowledge of radiative convective interactions is key to an understanding of the tropical climate. In an attempt to address this a cloud-resolving model has been run to a radiative-convective equilibrium state in three dimensions. The model includes a three-phase bulk microphysical scheme and a fully interactive two-stream broadband radiative-transfer scheme for both the infrared and solar radiation. The simulation is performed using a fixed sea surface temperature, and cyclic lateral boundary conditions. No 'large-scale' convergence, mean wind shear or background vorticity was imposed. The total integration lasted 70 days, and a statistical equilibrium state was reached at all heights after 30 days of simulation in all model variables. It is seen that some variables, such as vertical mass flux, adjust quickly to their equilibrium values while others, such as column-integrated water amount, domain-mean temperature and convective available potential energy (CAPE) display variation on a longer 30 day time-scale. The equilibrium state had a column-integrated vapour amount of 42.3 km m-2, a mean temperature of 258.7 K and a pseudo-adiabatic CAPE value of 1900 J kg-1. The equilibrium-state statistics are consistent with tropical observations. The convection does not remain randomly distributed but instead becomes organized, aligning in a band structure associated with high moisture values in the boundary layer. This organization seems to result from interactions between radiation, convection and surface fluxes. The surface-flux feedback is due to higher boundarylayer winds, associated with convection, increasing surface fluxes of moisture feedback is due to higher boundary winds, associated with convection, increasing surface fluxes of moisture locally. Horizontally inhomogeneous radiation can act to make clouds longer lasting and also increase convergence into cloudy region. Replacing the wind-sensitive surface-flux calculation with a linear relaxation to surface values appeared to largely destroy this organization, as did the use of an imposed horizontally uniform radiative-heating rate."
"57203200427;","On aerosol direct shortwave forcing and the Henyey-Greenstein phase function",1998,"10.1175/1520-0469(1998)055<0128:OADSFA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031806979&doi=10.1175%2f1520-0469%281998%29055%3c0128%3aOADSFA%3e2.0.CO%3b2&partnerID=40&md5=fb3cdff682dce59d88e530466257ab2d","This technical note extends previous Mie calculations to show that there are complex relationships between the asymmetry parameter g and the upscatter fractions for monodirectional incident radiation β(μ0). Except for intermediate zenith angles and for the upscatter fraction for diffuse radiation, there are significant differences between β(μ0) predicted by the Mie theory and that approximated by a Henyey-Greenstein phase function. While the Henyey-Greenstein phase function is widely used in radiative transfer calculations to characterize aerosol or cloud droplet scattering, it may cause important discrepancies in the computation of the aerosol direct radiative forcing, depending on solar zenith angle, aerosol size, and refractive index. The implications of this work for aerosol and climate-related studies are also discussed."
"56631063700;6701675843;6602613489;7201974896;6507814996;","An improved detection and characterization of active fires and smoke plumes in south-eastern Africa and Madagascar",1998,"10.1080/014311698214424","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032552474&doi=10.1080%2f014311698214424&partnerID=40&md5=3bf9831d8179ac18198942b82a99daee","The present study proposes improved multispectral methods for the detection of vegetation fires and smoke plumes that are applied to south-eastern Africa and Madagascar. Data are provided by the AVHRR sensor onboard the NOAA (11 and 14) satellites. Improvements of a multispectral methods address to fire detection difficulties arising from the low saturation level of AVHRR channel 3, from the presence of clouds and from contrasted vegetation and climate conditions. The methods are based on a multi-channel algorithm using AVHRR data, in visible and thermal ranges. Results are checked against other algorithm and ground concurrent data. It is shown that the presented multispectral methods are able to detect vegetation fires and associated smoke plumes with an improved accuracy. The results evidence clearly the seasonal character of biomass burning. Two maxima are characterized in the reference zone: one in September in Mozambique and the other in October in Eastern Madagascar. We note that fire intensity maxima were accompanied by well developed smoke plumes which could reach more than 50km. © 1998 Taylor & Francis Ltd."
"7401776640;7601332830;7402966758;","Role of low clouds in summertime atmosphere-ocean interactions over the North Pacific",1998,"10.1175/1520-0442(1998)011<2482:ROLCIS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032194342&doi=10.1175%2f1520-0442%281998%29011%3c2482%3aROLCIS%3e2.0.CO%3b2&partnerID=40&md5=171fc3a12c7967db9697de8693d24b16","The summer-to-summer variability of the areal extent of marine stratiform cloudiness (MSC; stratus, stratocumulus, and fog) over the North Pacific is examined for the period of record 1952-92 using a dataset based on surface observations. Variability is largest in two regions: the central and western Pacific along 35°N coincident with a strong meridional gradient in climatological MSC amount, and the eastern Pacific near 15°N downstream of the persistent stratocumulus deck off Baja California. The MSC amount in both regions tends to be negatively correlated with local sea surface temperature (SST), suggestive of a positive cloud feedback on SST. The MSC amounts in the two regions also tend to be negatively correlated by virtue of their relationship to the basin-wide sea level pressure (SLP) field: a strengthening of the seasonal mean subtropical anticyclone is accompanied by increased cloudiness in the trade wind regime and decreased cloudiness in the southerly flow farther toward the west. These relationships are reflected in the leading modes derived from empirical orthogonal function analysis and singular value decomposition analysis of the MSC, SST, and SLP fields. From the 1950s to the 1980s, summertime MSC amounts increased in the central and western Pacific and decreased in the trade wind region, while SST exhibited the opposite tendencies. Although these trends contributed to the relationships described above, similar patterns are obtained when the analysis is performed on 1-yr difference fields (e.g., 1953 minus 1952, 1954 minus 1953, etc.). Hence, it appears that MSC plays an important role in atmosphere-ocean coupling over the North Pacific during the summer season when latent and sensible heat fluxes are not as dominant and the coupling between atmospheric circulation and SST is not as strong as in winter.The summer-to-summer variability of the areal extent of marine stratiform cloudiness (MSC) over the North Pacific was examined for the period of record 1952-1992 using a dataset based on surface observations. The variability was largest in the central and western Pacific along 35°N coincident with a strong meridional gradient in climatological MSC amount, and the eastern Pacific near 15°N downstream of the persistent stratocumulus deck off Baja, California. The MSC amount in both regions negatively-correlate with local sea surface temperature, and to the basin-wide sea level pressure field."
"7402383878;7405666962;7402105994;7006385747;7004942632;57193920163;","Evolution of tropospheric ozone radiative forcing",1998,"10.1029/1998GL900037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032179447&doi=10.1029%2f1998GL900037&partnerID=40&md5=4bdab460ffe92a4690823bfb26f29ee2","We present the first estimate of the evolution of tropospheric ozone (O3(T)) radiative forcing since 1860 and into the future. The UKMO 3-D chemistry-transport model (STOCHEM) was used to simulate the tropospheric composition in 1860,1950, 1970, 1990 and 2100, by changing trace gas emissions. The future scenario used a doubled CO2 climate. STOCHEM includes extensive non-methane hydrocarbon (NMHC) chemistry, and produces a reasonable simulation of present-day O3(T). Radiative forcings caused by the modelled changes in O3(T) since 1860 were calculated using the UKMO radiation code, and included clouds and stratospheric temperature adjustment. Calculated changes in the global annual mean forcing since 1860 were 0.13, 0.22, 0.29 and 0.48 W m-2 for the four years. Up to 1990 this forcing scales linearly with the change in total NOx emissions since 1860; this linearity breaks down in 2100. The 1990 forcing is at the lower end of the range from previous modelling studies (0.28 - 0.51 W m-2), but is still significant, enhancing the well-mixed greenhouse gas forcing by over 10%. Copyright 1998 by the American Geophysical Union."
"7404586141;","Climate and residential electricity consumption in Hong Kong",1998,"10.1016/S0360-5442(97)00053-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031934580&doi=10.1016%2fS0360-5442%2897%2900053-4&partnerID=40&md5=721c7a0434d5c9d048da24ec204820e0","The influence of climatic variables on variations in residential electricity consumption (rec) in Hong Kong for the period 1980-1994 has been investigated. The association between a potential weather stress index, clo, and rec was also examined. Utilizing monthly data and stepwise multiple regression analyses, it was found that the vapor pressure was not significantly related to rec while cloud cover was associated with rec in summer only. The mean temperature was strongly correlated with rec. The use of clo demonstrated a strong relation to rec, with R2 equal to 0.823 for the whole period and 0.894 for the summer. These results indicate that clo could replace weather variables in modeling rec.The influence of climatic variables on variations in residential electricity consumption (rec) in Hong Kong for the period 1980-1994 has been investigated. The association between a potential weather stress index, clo, and rec was also examined. Utilizing monthly data and stepwise multiple regression analyses, it was found that the vapor pressure was not significantly related to rec while cloud cover was associated with rec in summer only. The mean temperature was strongly correlated with rec. The use of clo demonstrated a strong relation to rec, with R2 equal to 0.823 for the whole period and 0.894 for the summer. These results indicate that clo could replace weather variables in modeling rec."
"6603081424;23476370700;","Plane parallel albedo biases from satellite observations. Part II: parameterizations for bias removal",1998,"10.1175/1520-0442(1998)011<0933:PPABFS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031665865&doi=10.1175%2f1520-0442%281998%29011%3c0933%3aPPABFS%3e2.0.CO%3b2&partnerID=40&md5=4c55ba0183c67cdd0c5aa0d92a3f292c","Using the same satellite observations as in Part I of this paper, the authors explore ways to remove the cloud albedo bias (or plane parallel albedo bias), the difference between the plane parallel homogeneous albedo and the average albedo of independent pixels, in regions similar in size to climate model grid boxes. Scaling regional mean optical depths with the reduction factor of R.F. Cahalan et al. provides albedos close to the independent pixel values. Computed albedos approach the independent pixel values within 0.01 for ~40% of the regions tested and give standard deviations ~0.02-0.04. Fitting lognormal distributions to the observed optical depth distributions gives albedos within 0.01 of the independent pixel values more than 70% of the time, with standard deviations ~0.02-0.06. Gamma distributions are less successful than lognormal distributions, giving acceptable results (average bias ~0.01-0.02, standard deviation ~0.05-0.08) only when their parameters are estimated from the maximum likelihood estimates method. The poor performance of the gamma distribution when the method of moments is used for parameter estimation (as H.W. Barker et al. did) is attributed to the presence of high optical depth values in our retrieved fields. To apply any of the above corrections in GCMs, quantities that are not presently provided by these models are required. The reduction factor and 'gamma IP' method require the mean logarithm of optical depth, whereas the lognormal method also requires the variance. The authors suggest a parameterization of these quantities in terms of mean optical depth and cloud fraction, variables available in most GCMs. The albedos resulting from the parameterized versions of the correction methods are still much closer to the independent pixel values than the albedos of the plane parallel homogeneous assumption. Although the 'lognormal IP' gives the best overall performance, it requires knowledge of two logarithmic moments and numerical integration. It may therefore prove more appealing for observational than modeling applications."
"7003582587;7003495982;","The importance of the horizontal advection of hydrometeors in a single-column model",1998,"10.1175/1520-0442(1998)011<2437:TIOTHA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032455258&doi=10.1175%2f1520-0442%281998%29011%3c2437%3aTIOTHA%3e2.0.CO%3b2&partnerID=40&md5=6fd555bf9a6d4f51bea85dab2f34f55d","Single-column models (SCMs) are typically forced with profiles of vertical velocity and the divergence of water vapor and temperature due to horizontal advection. Vertical profiles of wind speed are also usually included to provide information required by model physics routines. What is not usually considered, probably because it is not typically available, is the divergence of hydrometeors due to horizontal advection. This paper uses output from a mesoscale model to provide forcing for an SCM. The mesoscale model contained a bulk microphysical scheme and, therefore, the forcing dataset allows a sensitivity study into the effect of the divergence of hydrometeors due to horizontal advection on various parameters in the SCM. It is shown that although the divergence of hydrometeors is typically smaller than the divergence of water vapor, at times it can be larger, particularly at upper levels (above 500 mb). By forcing the SCM with and without the divergence of hydrometeors included, it is shown that the term can significantly affect cloud water content, specific humidity, temperature, and other fields in the model. Including the divergence of hydrometeors into the water vapor divergence term does not always give the same results as including it as a separate field; however, some of the time it does, and is more physically based than ignoring the term completely."
"7003627420;6602314510;","Vegetation dynamics, palaeoenvironments and climatic changes in the forests of western Cameroon during the last 28,000 years B.P.",1998,"10.1016/S0034-6667(97)00047-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031955088&doi=10.1016%2fS0034-6667%2897%2900047-X&partnerID=40&md5=4b68b5039ee9a98f488778613c96bb7b","The lake Barombi Mbo pollen record goes back to about 28,000 yr B.P. The pollen diagram based on 82 samples is subdivided into four main pollen zones. Zone I (ca. 28,000 to 20,000 yr B.P.) is characterized by relatively high frequencies of Caesalpiniaceae and also by a montane element with Olea capensis. The climate was cool and relatively wet. Zone II (ca. 20,000 to 10,000 yr B.P.). A sharp increase in Gramineae, the main non-arboreal land pollen taxon, began around 20,000 yr B.P. and lasted until 10,000 yr B.P. During this period the forest receded, giving way to a more open vegetation, but significant patches of forest (refuges) persisted in the area. This is confirmed by isotopic analyses (δ13C) of sedimentary detritic organic matter from the catchment. Until ca. 13,000 yr B.P. Olea capensis was well represented indicating a relatively cool climate. Between 13,000 and 12,000 yr B.P. a warming trend associated with a strong increase in precipitation occurred. After this an abrupt reduction in precipitation linked to an increase in seasonality, but without temperature lowering, intervened between ca. 11,500 and 10,400 yr B.P. This last phase corresponds partly to the Younger Dryas time period. Zone III (ca. 10,000 to 2800 yr B.P.). After ca. 10,400 yr B.P. the climate became very wet until ca. 3000 yr B.P. A sharp decrease in the Gramineae intervened at ca. 10,000 yr B.P.; from ca. 9500 to 3000 yr B.P. they remained very low, between 0 and 3%, and the forest trees reached their maximum extension. Most of the trees exhibited large variations with quasi-periods of around 1000 to mainly 2000 yr (ca. 2200 calendar years), which could be related to large sylvigenetic or successional cycles. In this zone the Caesalpiniaceae were relatively well represented, with a maximum extension between 4500 and 3000 yr B.P. Podocarpus, a typical tree of the montane stratiform cloud forests, exhibited very low frequencies before 10,000 yr B.P. but their relative increase during the early and middle Holocene can only be explained by its growth on distant mountains. Its maximum extension phase was roughly synchronous with that of Caesalpiniaceae. The climate was warm and wet, but cooler on the mountains. Zone IV (ca. 2800 yr B.P. to present time). Around 2800 yr B.P. a sharp increase in the Gramineae, peaking at 30 to 40% of total pollen between ca. 2500 and 2000 yr B.P., indicates a sudden phase of vegetation opening and forest retreat, accompanied by severe erosion. Alchornea, a typical pioneer taxon, increased rapidly at the same time to large frequencies because it develops abundantly in all the openings. Elaeis guineensis, originally a pioneer palm tree, follows the same pattern. The climate was warm, relatively dry, and linked to an increase of seasonality. After 2000 yr B.P. the Gramineae returned to low frequencies, around 10%, associated with a strong increase in trees, indicating that the forest expanded again but not to the same extent as in the early and middle Holocene. The climate was warm and relatively wet, rather similar to the present-day climate."
"7006644185;6603579557;7004159570;","Timing and synchrony of parturition in Alaskan moose: Long-term versus proximal effects of climate",1998,"10.2307/1383025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0542396666&doi=10.2307%2f1383025&partnerID=40&md5=7a416460eb964515c51852c4e3e99d31","We studied timing and synchrony of parturition in Alaskan moose (Alces alces) in Denali National Park and Preserve, Alaska, from 1990 to 1994. Mean date of birth was 25 May (SD = 5.7 days) and did not differ significantly among years. Although moose did not congregate to give birth, parturition was highly synchronized (95% of births occurred in 16 days) with no significant differences among years. Most young moose were killed by predators, especially grizzly bears (Ursus arctos), but timing of reproduction had no effect on survivorship of young, which was low (ca. 0.2 by 16 June). We reject the hypothesis that moose timed births to avoid predation. We also measured depth of snow in winter, and precipitation, cloud cover, and temperature in spring; none of these variables was related to timing or synchrony of births. Likewise, quality of willow (Salix pulchra) in 3 springs in which percent nitrogen and in vitro dry-matter digestibility of this important forage varied markedly was unrelated to timing of births. We reject the hypothesis that moose timed parturition in response to proximal changes in their environment. We hypothesize that both timing and synchrony of parturition in moose are adaptations to long-term patterns of climate that provide the most hospitable conditions to bear and rear young. Consequently, moose may be more susceptible to climatic change than other ungulates that are more adapted to climatic variability."
"7403884267;7601443168;","Evolution of katabatic flow on the island of Hawaii on 10 august 1990",1998,"10.1175/1520-0493(1998)126<2185:EOKFOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032458172&doi=10.1175%2f1520-0493%281998%29126%3c2185%3aEOKFOT%3e2.0.CO%3b2&partnerID=40&md5=b9bbfc99977f33613d9988e6c69d4892","The data collected on 10 August 1990 from the Hawaiian Rainband Project were analyzed to study the evolution of katabatic flow. Results from this study show that for a relatively dry case thermal forcing is important to account for the onset, evolution, depth, and offshore extension of the katabatic flow on the windward side of the island of Hawaii where the mean winds are weak because of island blocking. During the evening transition, the initiation of katabatic flow on the windward slopes was mainly driven by the diurnal heating cycle. At the windward coast, the wind shift was caused by the arrival of the drainage front from the windward lowlands. After the arrival of the drainage front at Hilo, slopewise instability was generated because of rain showers along the coast and diminishing orographic clouds and showers on the slopes. Along the coast, because of the reduced radiative cooling due to cloud cover and vertical mixing associated with rains, a warm period was observed at Hilo. On the slopes, the katabatic flow dissipated the orographic clouds and produced strong surface radiative cooling. As a result, the surface air on the lower slopes became potentially colder than the surface air along the coast and continued to move downward toward the coast. Furthermore, because of surface radiative cooling, the surface air at higher elevations moved to lower elevations along the isentropic surfaces but remained within the katabatic flow. With continued cold air advection down the slope under opposing trade winds, the nocturnal inversion was deeper along the coast than on the windward slopes. Throughout the night, the katabatic flow extended gradually over the ocean. A narrow updraft of ∼0.5 m s-1 was observed along the leading edge of the offshore flow, which resembled a density current. The location of the convergence zone between the offshore flow and the incoming trade winds is related to the offshore extension of katabatic flow and is not solely determined by the upstream Froude number."
"55802246600;25652514900;7402803216;35265615300;","Seasonal and Spatial Variation of Radiative Effects of Anthropogenic Sulfate Aerosol",1998,"10.1007/s00376-998-0008-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2742550016&doi=10.1007%2fs00376-998-0008-6&partnerID=40&md5=a09e6b18ddfc839fda30ca7f7e6acec9","On the basis of the emission data of the industrial sulphur dioxide (SO2) and observed climate fields over East Asia, the distribution of anthropogenic sulfate aerosol(SO42-) with seasonal variation in the troposphere is simulated and analyzed by a regional sulfur transport model, and the direct radiative effects of SO42- under different weather conditions are also calculated using the discrete ordinate method. The results show that the concentration of SO42- has significant seasonal and spatial variations resulting from the effects of SO2 emission source and precipitation and wind fields. Both the concentration of SO2 and its radiative forcing have the largest values in October and the lowest in July. SO42- causes the decrease of the radiation flux absorbed by earth-atmosphere and the cooling of air temperature by scattering more solar radiation back into space. Besides, the radiative and climatic effects of SO42- are related to the types and height and optical thickness, etc., of the clouds."
"7004194999;7003535176;6602831555;55684491100;","A diagnostic study of the global distribution of contrails Part I: Present day climate",1998,"10.1007/s007040050058","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032429101&doi=10.1007%2fs007040050058&partnerID=40&md5=9106e04c717dd23d2b78b089ceca748b","The global distribution of contrail formation potential and contrail cloud coverage are estimated using meteorological analyses of temperature and humidity (ECMWF reanalyses) and an aircraft fuel inventory. A large potential for contrail formation is found in the upper troposphere, in particular in the tropics, but also at mid-latitudes. The global potential contrail coverage is calculated to be 16%. The actual contrail coverage is proportional to the product of the potential coverage and the fuel consumption of 1991/92 air traffic. The actual global contrail coverage is 0.09%, however, the pattern of main air routes show up in the geographical distribution of contrail coverage with maximum values of more than 5%. Regionally, contrail coverage shows a distinct annual cycle, with larger values in winter than in summer, in the mid-latitudes. The result is only weakly sensitive to the propulsion efficiency of aircraft, but strongly sensitive to aircraft flight altitude."
"7404395984;7103267885;7005118516;","The use of pattern recognition to derive SSMT/2 moisture retrievals",1998,"10.1016/S0273-1177(97)00917-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031745770&doi=10.1016%2fS0273-1177%2897%2900917-4&partnerID=40&md5=06c26c4dbba417bc31619f696de978a2","Global moisture distribution plays an important role in understanding and predicting weather and climate. A retrieval algorithm for deriving atmospheric moisture profiles has been developed for the Special Sensor Microwave Temperature-2 (SSMT/2) sensor aboard DMSP satellites. The algorithm uses pattern recognition to select the first guess to be used in a regression retrieval and an adjustment procedure to remove cloud liquid water contamination from the measurements. The accuracy of the first guess exceeds that of statistical retrievals which starts with a climatological guess. The pattern recognition technique is library search in which ensembles of collocated radiosonde and satellite observations are used to find situations that are similar to the ambient condition. The average of the ten most similar conditions provide the moisture guess and the corresponding SSMT/2 brightness temperature guess. For very nonlinear problems (i.e. moisture retrievals), library search solutions alone are consistently better than regression solutions."
"7202295135;7402237792;6602920608;7004131737;6507354929;7005481367;","Regional application of an ecosystem production model for studies of biogeochemistry in Brazilian Amazonia",1998,"10.1046/j.1365-2486.1998.00154.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031832744&doi=10.1046%2fj.1365-2486.1998.00154.x&partnerID=40&md5=a04bba95f1c9bd2384ba7e07adbae44d","The degree to which primary production, soil carbon, and trace gas fluxes in tropical forests of the Amazon are limited by moisture availability and other environmental factors was examined using an ecosystem modelling application for the country of Brazil. A regional geographical information system (GIS) serves as the data source of climate drivers, satellite images, land cover, and soil properties for input to the NASA Ames-CASA (Carnegie-Ames-Stanford Approach) model over a 8-km grid resolution. Simulation results lead us to hypothesize that net primary production (NPP) is limited by cloud interception of solar radiation over the humid north-western portion of the region. Peak annual rates for NPP of nearly 1.4 kg C m-2 year-1 are localized in the seasonally dry eastern Amazon in areas that we assume are primarily deep-rooted evergreen forest cover. Regional effects of forest conversion on NPP and soil carbon content are indicated in the model results, especially in seasonally dry areas. Comparison of model flux predictions along selected eco-climatic transects reveal moisture, soil, and land use controls on gradients of ecosystem production and soil trace gas emissions (CO2, N2O, and NO). These results are used to formulate a series of research hypotheses for testing in the next phase of regional modelling, which includes recalibration of the light-use efficiency term in NASA-CASA using field measurements of NPP, and refinements of vegetation index and soil property (texture and potential rooting depth) maps for the region."
"7006235116;6506070399;7201443806;7004427298;","Air-sea interaction mechanisms and low-frequency climate variability in the south indian ocean region",1998,"10.1002/(SICI)1097-0088(19980330)18:4<391::AID-JOC253>3.0.CO;2-C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031815567&doi=10.1002%2f%28SICI%291097-0088%2819980330%2918%3a4%3c391%3a%3aAID-JOC253%3e3.0.CO%3b2-C&partnerID=40&md5=50de75b2cdd4c6774850f07b3aea004f","Long-term observations indicate that the Indian Ocean displays significant low-frequency variability in mean sea-level pressure, near-surface wind, cloud and sea-surface temperature (SST). A general circulation model is used to study the response of the atmosphere to an idealized SST anomaly pattern (warm in southern mid-latitudes, cool in southern tropics) that captures the essence of observed multidecadal SST variability as well as that associated with ENSO in the South Indian Ocean. The major objectives are to investigate air-sea interaction mechanisms potentially associated with the variability and whether the atmospheric response to the SST is likely to lead to maintenance or damping of the original SST anomaly pattern, and on what time scale. Two types of experiment are performed to tackle these objectives. An ensemble of roughly 1-year-long integrations suggests that the seasonal-scale response of the atmosphere to the imposed SST anomaly includes reduced genesis and density of cyclones in the mid- to higher latitudes, and an indication of a shift in their tracks relative to climatology. It is argued that these changes together with those to the near-surface winds could be expected to lead to variations in surface fluxes that would tend to reinforce the original SST anomaly pattern on seasonal scales. A 21 year integration of the model with the SST anomaly pattern imposed throughout indicates that a low is generated near, and downstream of, the warm mid-latitude anomaly. On decadal/multidecadal scales, the associated changes to the surface winds are argued as being likely to lead to changes in surface fluxes and in the strength of the South Indian subtropical gyre that would oppose the original anomaly. The current and previous model results together with the observations then support the idea that the observed multidecadal variability in atmospheric circulation and SST of the South Indian Ocean during the past century may have arisen through a combination of basin scale atmosphere-ocean interaction and a remotely forced component. © 1998 Royal Meteorological Society."
"7004697125;6601993613;","Determination and parameterization of some air pollutants as a function of meteorological parameters in kayseri, Turkey",1998,"10.1080/10473289.1998.10463738","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0344110381&doi=10.1080%2f10473289.1998.10463738&partnerID=40&md5=d39bd608aa85a02341b2d19fc924e17c","In this paper, the statistical relations between meteorological parameters and some pollutant ground level concentrations are presented. The daily average sulfur dioxide and smoke values were measured at five stations in Kayseri over 20 months. The model adopted for analysis differed from the power-law form selected by former investigators. Wind speed, degree-day temperature, the percentage of relative humidity, the previous day’s pollution concentrations, and the amount of global solar radiation were the variables of multiple regression equations that were derived to calculate pollutant concentrations. The amount of cloud cover, however, had no important effect on the pollutant concentrations. The average variances of these regression equations were found as 84 and 75% for sulfur dioxide and smoke concentrations, respectively. The calculated pollutant concentrations utilizing forecast meteorological parameters reflected that the occurrence of high pollutant concentrations can be predicted. © 1998 Air and Waste Management Association."
"6602952210;35357775100;","Earth-average temperature: A time delay approach",1998,"10.1029/98JD02273","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573256&doi=10.1029%2f98JD02273&partnerID=40&md5=e67ee258f3adad0c1addec2ef19d6a8e","Earth-average temperature is investigated using a simple energy balance model of the Budyko-Sellers-Ghil type expressed as a delay-differential equation describing the absorption and reflection of incoming solar radiation and surface-reflected infrared radiation. Cloud albedos for both radiations and the surface albedo as affected by ice coverage are assumed to depend upon the temperature that existed some time ago, introducing a time delay into the model. A variety of steady and oscillatory states are possible for Earth-average temperature, assuming plausible functions for the albedos, blackbody cooling, and suitable delay times. Multiple true steady states and multiple transient pseudo steady states as well as periodic, chaotic, and square-wave relaxation-oscillations result. The bifurcation structure relating the appearance of these phenomena to system parameters is explored. This very simple climate model exhibits complex behavior in global temperature without solar variation or environmental perturbation. Bifurcations exist at which small changes in parameters lead to destabilization of steady states and dramatic changes in qualitative behavior. Copyright 1998 by the American Geophysical Union."
"7006241374;22973650100;7102876791;6507211894;57217875699;7003512303;6507251479;7801454597;","The sharp rise of Δ14C ca. 800 cal BC: Possible causes, related climatic teleconnections and the impact on human environments",1998,"10.1017/s0033822200018403","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032468703&doi=10.1017%2fs0033822200018403&partnerID=40&md5=05d9949013fb75f32872dd91ce7279e0","In this study we report on accelerator mass spectrometry (AMS) wiggle-match dating of selected macrofossils from organic deposits ca. 800 cal BC (ca. 2650 BP). Based on paleological, archaeological and geological evidence, we found that the sharp rise of atmospheric 14C between 850 and 760 cal BC corresponds to the following related phenomena: 1. In European raised bog deposits, the changing spectrum of peat forming mosses and a sharp decline in decomposition of the peat indicate a sudden change from relatively dry and warm to cool, moist climatic conditions. 2. As a consequence of climate change, there was a fast and considerable rise of the groundwater table so that peat growth started in areas that were already marginal from a hydrological point of view. 3. The rise of the groundwater table in low-lying areas of the Netherlands resulted in the abandonment of settlement sites. 4. The contemporaneous earliest human colonization of newly emerged salt marshes in the northern Netherlands (after loss of cultivated land) may have been related to thermal contraction of ocean water, causing a temporary stagnation in the relative sea-level rise. Furthermore, there is evidence for synchronous climatic change in Europe and on other continents (climatic teleconnections on both hemispheres) ca. 2650 BP. We discuss reduced solar activity and the related increase of cosmic rays as a cause for the observed climatological phenomena and the contemporaneous rise in the 14C-content of the atmosphere. Cosmic rays may have been a factor in the formation of clouds and precipitation, and in that way changes in solar wind were amplified and the effects induced abrupt climate change."
"7409734588;7409950488;","The relation of sky view factors and wind to nocturnal city temperatures in Nagano city",1998,"10.4157/grj1984a.71.6_436","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031725970&doi=10.4157%2fgrj1984a.71.6_436&partnerID=40&md5=390d5b0ae666af5cdfc53ca67155c026","Air temperature distributions at night in Nagano city were measured in 1996. The population of Nagano city is about 350 000. The measurements were done a total of 27 times at each of 47 points by the automobile traverse method. Other meteorological dlement data used were from measurements of the Nagano Local Meteorological Observatyory. Sky view factorsθ in each point were measured with fisheye photographs. The results were as follows: (1) As the sky view factors increased, night-time city temperatures decreased on November 3 with clear skies and wind of 0.7 m/s, which was the weakest during this research. But in 14 cases when wind speed was less than 1.5 m/s, the largest correlation coefficient between city temperature ΔT and θ was 0.4, and so this relation seemed to be irrelevant. It was also suggested that this relation did not depend on the amount of cloud cover. (2) The effect of wind on city temperature distributions was confirmed in the expansion of warm areas. But the leeward shift of point which showed the maximum temperature was not observed."
"35464731600;35573513700;7006927046;7103129868;7003741536;57205779812;35466821900;7102063963;7004467879;","Potential global fire monitoring from EOS-MODIS",1998,"10.1029/98JD01644","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573698&doi=10.1029%2f98JD01644&partnerID=40&md5=aa296d0b7c4472083c2cf8675bf9aa27","The National Aeronautic and Space Administration (NASA) plans to launch the moderate resolution imaging spectroradiometer (MODIS) on the polarorbiting Earth Observation System (EOS) providing morning and evening global observations in 1999 and afternoon and night observations in 2000. These four MODIS daily fire observations will advance global fire monitoring with special 1 km resolution fire channels at 4 and 11 μm, with high saturation of about 450 and 400 K, respectively. MODIS data will also be used to monitor burn scars, vegetation type and condition, smoke aerosols, water vapor, and clouds for overall monitoring of the fire process and its effects on ecosystems, the atmosphere, and the climate. The MODIS fire science team is preparing algorithms that use the thermal signature to separate the fire signal from the background signal. A database of active fire products will be generated and archived at a 1 km resolution and summarized on a grid of 10 km and 0.5°, daily, 8 days, and monthly. It includes the fire occurrence and location, the rate of emission of thermal energy from the fire, and a rough estimate of the smoldering/flaming ratio. This information will be used in monitoring the spatial and temporal distribution of fires in different ecosystems, detecting changes in fire distribution and identifying new fire frontiers, wildfires, and changes in the frequency of the fires or their relative strength. We plan to combine the MODIS fire measurements with a detailed diurnal cycle of the fires from geostationary satellites. Sensitivity studies and analyses of aircraft and satellite data from the Yellowstone wildfire of 1988 and prescribed fires in the Smoke, Clouds, and Radiation (SCAR) aircraft field experiments are used to evaluate and validate the fire algorithms and to establish the relationship between the fire thermal properties, the rate of biomass consumption, and the emissions of aerosol and trace gases from fires. Copyright 1998 by the American Geophysical Union."
"6603387582;","Humidity in the ECMWF model: Monitoring of operational analyses and forecasts using SSM/I observations",1998,"10.1256/smsqj.54813","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031665478&doi=10.1256%2fsmsqj.54813&partnerID=40&md5=1331c27f3c5f46356f9a0f61c15b9a74","Over oceans, total column water vapour (TCWV) estimates derived from brightness temperatures of the Special Sensor Microwave Imager (SSM/I) have been shown to give accuracies similar to radiosonde measurements. Data provided by the SSM/I on the DMSP satellites are not available in real-time, and so they are not assimilated into the ECMWF model. They can thus be used for independent validation of this important aspect of the model's hydrological cycle. The quality of ECMWF operational analyses of humidity is assessed for the period between August 1992 and November 1994. At that time, assimilation was performed through an Optimal Interpolation scheme. For this work, 2-week averages of TCWV have been computed from analysis humidity fields of the ECMWF model and compared with simultaneous SSM/I estimates. Discrepancies between model and SSM/I estimates associated with different meteorological regimes are discussed. According to the season, the underestimation of analysed humidity in the tropics can reach 30 to 50%, whereas oceanic subsidence areas located off western coasts of subtropical continents appear too wet by as much as 60%. Mid-latitudes are generally too moist, but to a lesser extent. An example is also shown of the utilization of SSM/I TCWV to evaluate the impact of an experimental prognostic cloud scheme on analyses and forecasts."
"35498837200;7006739521;7005524881;","Surface ocean fluxes and water-mass transformation rates in the coupled NCAR climate system model",1998,"10.1175/1520-0442(1998)011<1420:SOFAWM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031663907&doi=10.1175%2f1520-0442%281998%29011%3c1420%3aSOFAWM%3e2.0.CO%3b2&partnerID=40&md5=1c2796a620f146797b52e967f4a65131","The global distributions of the air-sea fluxes of heat and freshwater and water mass transformation rates from a control integration of the coupled National Center for Atmospheric Research (NCAR) Climate System Model (CSM) are compared with similar fields from an uncoupled ocean model equilibrium spinup and a new surface climatology. The climatology and uncoupled model use the same bulk-flux forcing scheme and are forced with National Centers for Environmental Prediction (formerly the National Meteorological Center) atmospheric reanalysis data and satellite-based cloud cover, solar flux, and precipitation estimates. The climatological fluxes for the open ocean are adjusted to give a global net balance and are in broad general agreement with standard ship-based estimates. An exception is the ice-free Southern Ocean, where the net heat and evaporative fluxes appear to be too weak but where the observational coverage underlying the reanalysis is quite poor. Major differences are observed between the climatology and the NCAR CSM coupled solution, namely, enhanced tropical and subtropic solar insolation, stronger energy and hydrologic cycles, and excessive high-latitude ice formation/melt producing a several-fold increase in Arctic and Antarctic deep water formation through brine rejection. The anomalous fluxes and corresponding water-mass transformations are closely tied to the coupled ocean model drift, characterized by a reorganization of the vertical salinity distribution. Some error features in the heat flux and sea surface temperature fields are common to both the coupled and uncoupled solutions, primarily in the western boundary currents and the Antarctic circumpolar current, and are thus likely due to the poor representation of the circulation field in the coarse-resolution NCAR ocean model. Other problems particular to the uncoupled spinup are related to the bulk-flux forcing scheme, an example being excess freshwater deposition in the western boundary currents arising from the inclusion of a weak open ocean surface salinity restoring term. The effective thermal restoring coefficient, which relates the change in nonsolar surface heat flux to sea surface temperature changes, is on average 14.6 W m-2 K-1 for the coupled solution or about a third of the range from the bulk flux forcing scheme, 40-60 W m-2 K-1."
"36705143500;56250185400;","Climate response to soil dust aerosols",1998,"10.1175/1520-0442(1998)011<3247:CRTSDA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032416288&doi=10.1175%2f1520-0442%281998%29011%3c3247%3aCRTSDA%3e2.0.CO%3b2&partnerID=40&md5=4c909946a103d98c09aea1fdf537299c","The effect of radiative forcing by soil dust aerosols upon climate is calculated. Two atmospheric GCM (AGCM) simulations are compared, one containing a prescribed seasonally varying concentration of dust aerosols, and the other omitting dust. Each simulation includes a mixed layer ocean model, which allows SST to change in response to the reduction in surface net radiation by dust. Dust aerosols reduce the surface net radiation both by absorbing and reflecting sunlight. For the optical properties of the dust particles assumed here, the reflection of sunlight is largely offset by the trapping of upwelling longwave radiation, so that the perturbation by dust to the net radiation gain at the top of the atmosphere is small in comparison to the surface reduction. Consequently, the radiative effect of soil dust aerosols is to redistribute heating from the surface to within the dust layer. Beneath the dust layer, surface temperature is reduced on the order of 1 K, typically in regions where deep convection is absent. In contrast, surface temperature remains unperturbed over the Arabian Sea during Northern Hemisphere (NH) summer, even though the dust concentration is highest in this region. It is suggested that the absence of cooling results from the negligible radiative forcing by dust at the top of the atmosphere, along with the frequent occurrence of deep convection, which ties the surface temperature to the unperturbed value at the emitting level. Where convection is absent, cooling at the surface occurs because radiative heating by dust reduces the rate of subsidence (and the corresponding mass exchange with the convecting region). Thus, the temperature contrast between these two regions must increase to maintain the original transport of energy, which is unperturbed by dust. It is suggested that cooling over the Arabian Sea during NH winter, despite the much smaller dust loading, is permitted by the absence of convection during this season. Thus, the change in surface temperature forced by dust depends upon the extent of overlap between the dust layer and regions of deep convection, in addition to the magnitude of the radiative forcing. Surface temperature is also reduced outside of the dust cloud, which is unlikely to result solely from natural variability of the AGCM. It is suggested that the perturbation by dust to Indian and African monsoon rainfall may depend upon the extent to which ocean dynamical heat transports are altered by dust.The effect of radiative forcing by soil dust aerosols upon climate is calculated. Two atmospheric GCM (AGCM) simulations are compared, one containing a prescribed seasonally varying concentration of dust aerosols, and the other omitting dust. Each simulation includes a mixed layer ocean model, which allows SST to change in response to the reduction in surface net radiation by dust. Dust aerosols reduce the surface net radiation both by absorbing and reflecting sunlight. For the optical properties of the dust particles assumed here, the reflection of sunlight is largely offset by the trapping of upwelling longwave radiation, so that the perturbation by dust to the net radiation gain at the top of the atmosphere is small in comparison to the surface reduction. Consequently, the radiative effect of soil dust aerosols is to redistribute heating from the surface to within the dust layer. Beneath the dust layer, surface temperature is reduced on the order of 1 K, typically in regions where deep convection is absent. In contrast, surface temperature remains unperturbed over the Arabian Sea during Northern Hemisphere (NH) summer, even though the dust concentration is highest in this region. It is suggested that the absence of cooling results from the negligible radiative forcing by-dust at the top of the atmosphere, along with the frequent occurrence of deep convection, which ties the surface temperature to the unperturbed value at the emitting level. Where convection is absent, cooling at the surface occurs because radiative heating by dust reduces the rate of subsidence (and the corresponding mass exchange with the convecting region). Thus, the temperature contrast between these two regions must increase to maintain the original transport of energy, which is unperturbed by dust. It is suggested that cooling over the Arabian Sea during NH winter, despite the much smaller dust loading, is permitted by the absence of convection during this season. Thus, the change in surface temperature forced by dust depends upon the extent of overlap between the dust layer and regions of deep convection, in addition to the magnitude of the radiative forcing. Surface temperature is also reduced outside of the dust cloud, which is unlikely to result solely from natural variability of the AGCM. It is suggested that the perturbation by dust to Indian and African monsoon rainfall may depend upon the extent to which ocean dynamical heat transports are altered by dust."
"57212958778;","The interactive multisensor snow and ice mapping system",1998,"10.1002/(sici)1099-1085(199808/09)12:10/11<1537::aid-hyp679>3.0.co;2-a","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032221831&doi=10.1002%2f%28sici%291099-1085%28199808%2f09%2912%3a10%2f11%3c1537%3a%3aaid-hyp679%3e3.0.co%3b2-a&partnerID=40&md5=0433976c09ed26a0322b2b22165643ca","The interactive multisensor snow and ice mapping system (IMS) was developed to give snow and ice analysts the tools, on one platform, to inspect visually the imagery and mapped data from various sensor sources to determine the presence of snow and ice and to depict snow- and ice-covered areas on a map on a daily basis, in one hour or less. Snow and ice analysts in the National Environmental Satellite, Data, and Information Service have been creating weekly maps showing the extent of snow cover for the Northern Hemisphere since 1966 using visible imagery from polar-orbiting and geostationary satellites and surface observations as data sources. The current process is mostly manual and time-consuming, taking up to 10 hours to produce a map during the snow season. Where cloud cover precludes an unobstructed view of an area during the entire week, the analysis from the previous week is carried forward. Each week the analyst draws a new map by hand, then digitizes the extent of snow and ice cover using an 89 x 89 line grid overlaid on a stereographic map of the Northern Hemisphere. The hand-drawn map is photocopied and distributed and the digitized map is saved to a file for use in National Weather Service numerical models and for archival storage. IMS was designed and built to replace and improve this process by producing a more accurate and timely product. ©1998 John Wiley & Sons, Ltd. KEY WORDS satellite remote sensing; environmental data; snow and ice cover; geographic information system; climate."
"56962915800;7402761465;","Coupled modes of the warm pool climate system. Part I: The role of air-sea interaction in maintaining Madden-Julian oscillation",1998,"10.1175/1520-0442-11.8.2116","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032468665&doi=10.1175%2f1520-0442-11.8.2116&partnerID=40&md5=e5408c412f427ed47ffc99b08107e17e","Over the warm pool of the equatorial Indian and western Pacific Oceans, both the climatological mean state and the processes of atmosphere-ocean interaction differ fundamentally from their counterparts over the cold tongue of the equatorial eastern Pacific. A model suitable for studying the coupled instability in both the warm pool and cold tongue regimes is advanced. The model emphasizes ocean mixed layer physics and thermodynamical coupling that are essential for the warm pool regime. Different coupled unstable modes are found under each regime. In contrast to the cold tongue basic state, which favors coupled unstable low-frequency SST mode, the warm pool regime (moderate mean surface westerlies and deep thermocline) is conducive for high-frequency (intraseasonal timescale) coupled unstable modes. The wind-mixed layer interaction through entrainment/evaporation plays a central role in the warm pool instability. The cloud-radiation feedback enhances the instability, whereas the ocean wave dynamics have little impact. The thermodynamic coupling between the atmosphere and ocean mixed layer results in a positive SST anomaly leading convection, which provides eddy available potential energy for growing coupled mode. The relatively slow mixed layer response to atmospheric forcing favors the growth of planetary-scale coupled modes. The presence of mean westerlies suppresses the low-frequency SST mode. The characteristics of the eastward-propagating coupled mode of the warm pool system compares favorably with the large-scale features of the observed Madden-Julian Oscillation (MJO). This suggests that, in addition to atmospheric internal dynamic instability, the ocean mixed layer thermodynamic processes interacting with the atmosphere may play an active part in sustaining the MJO by (a) destabilizing atmospheric moist Kelvin waves, (b) providing a longwave selection mechanism, and (c) slowing down phase propagation and setting up the 40-50-day timescale."
"6602509764;7103133591;57201235812;55462544900;","Pacific warm pool temperature regulation during TOGA COARE: Upper ocean feedback",1998,"10.1175/1520-0442(1998)011<2297:PWPTRD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032462110&doi=10.1175%2f1520-0442%281998%29011%3c2297%3aPWPTRD%3e2.0.CO%3b2&partnerID=40&md5=e4ba7a8c71ca27c8aebf30b170c40943","The Hasselmann feedback model was applied to hindcast western Pacific warm pool sea surface temperatures (SST) with heat flux observations obtained near 2°S, 156°E from October 1992 to February 1993 during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). The model versus observed SST correlations were greater than 0.85. Two important feedback (or damping) timescales emerged, with e-folding times of λ-1 = 0.2 days and 8 days, fitting to the diurnal and subdiurnal variations, respectively. Distinct mixed layer depth scales were also found for the respective timescales. A time-varying depth parameter with a median of ~5 m was derived for the shorter timescale and varied with the observed daily minimum mixed layer depth. A constant ~16 m was optimal for the longer timescale, which is similar to the time-averaged observed mixed layer depth of 14.8 m and the Monin-Obukhov scale of ~17 m. This bears on the choice of mixed layer parameters for climate model simulations of warm pool conditions observed in TOGA COARE. The low-frequency time- and depth-scale parameters give a negative feedback of about 95 W m-2°C-1, which is significantly greater than previous studies have indicated. This restoring influence was treated separately from fluxes across the air-sea interface such as latent, radiative, and sensible heat loss or cloud shading, and is thus attributed to oceanic mixed layer processes. The frequency band where the damping or feedback becomes important is defined by ω ~ λ, which is found to coincide with the diurnal cycle and the ~50-day Madden-Julian oscillations for the respective λ-1 timescales. This indicates a possible dynamic connection between the surface heat forcing and mixed layer dissipation timescales, which the authors suggest might be accounted for if the dissipation is parameterized as being proportional to the amplitude of SST variations."
"7007005208;","Global expressions for seasonal temperatures of the sea surface and ambient air - The influence of tidal currents and water depth",1998,"10.1016/S0399-1784(98)80027-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032075883&doi=10.1016%2fS0399-1784%2898%2980027-3&partnerID=40&md5=4cfa403967e5d0713cf80bb22e158cf5","A 'single point' coupled ocean-atmosphere model is formulated to study seasonal temperature cycles with particular application to shelf seas. The simplified atmospheric module is consistent with the physical processes described by Gill [4] while the vertical exchange of heat in the ocean module is determined via a turbulence closure model. The various empirical coefficients in the atmospheric module were determined by fitting the model output to North Atlantic observational data over the latitude range 0°to 65°N. The model is then applied to the shallow, strongly tidal North Sea. The general validity of the model is demonstrated, thereby indicating that the seasonal cycles of the sea surface, T(s), and ambient air, T(a), are generally governed by a localised equilibrium. In shallow water (<200 m) the amplitude of this seasonal cycle is modulated by both the water depth and tidal current amplitude. North Sea observational data confirm these model indications that large tidal currents decrease seasonal amplitudes. This study provides, for the first time, a quantitative estimate of this influence of shallow seas on adjacent coastal climates. It is shown how the model results can be sensibly approximated by generalised expressions - illustrating that mean values of both T(s) and T(a) vary with the cosine of latitude (up to 65°N) while their seasonal amplitudes vary directly with latitude and inversely with an exponent of water depth. Thus these generalised expressions can be conveniently used to provide boundary conditions in generalised ecological models. The model can also be used for (small amplitude) sensitivity analyses to examine, for example, the effect of changes in storminess or cloud cover."
"7402721790;7102857642;56284545500;","Role of land surface processes associated with interannual variability of broad-scale Asian summer monsoon as simulated by the CCSR/NIES AGCM",1998,"10.2151/jmsj1965.76.2_217","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0006761181&doi=10.2151%2fjmsj1965.76.2_217&partnerID=40&md5=71203a80721ac2b110ef7b644f31b27c","The interannual variability of the South Asian summer monsoon and associated land-surface processes over the Eurasian continent in a ten-year integration (1979-88) of an atmospheric general circulation model (AGCM) forced by observed sea surface temperatures (SSTs) is examined. The AGCM has been developed jointly by the Center for Climate System Research (CCSR), the University of Tokyo, and the National Institute for Environmental Studies (NIES). A monsoon intensity index, based on the magnitude of summer-mean vertical shear of zonal wind over the south Asian monsoon region, is used to classify weak and strong monsoon years. It is found that the simulated interannual variability of broad-scale summer monsoon shows a good correlation with observations. Furthermore, distinct precursory signals, including the Eurasian snow in winter and soil moisture anomalies in spring, have been found in the pre-monsoon seasons of weak and strong monsoon years. There is a sharp contrast between weak and strong monsoon years; excessive snow over Eurasia south of 50°N in winter and the increased soil moisture in spring are found prior to weak summer monsoon. These results are consistent with evidence found in observational data analyses and some model experiments A detailed analysis of surface heat budget shows that snow-albedo feedback dominates over the Tibetan Plateau. On the other hand, to its west in the central Asia, the relatively lower land, the effective cloud albedo anomalies due to excessive rainfall and surface evaporation influence the surface conditions. A numerical experiment with the Eurasian land surface initial conditions in spring, interchanged between weak and strong monsoon years, indicates positive roles played by the land surface processes in influencing the subsequent summer monsoon circulations during the 10-year period. However, such land surface feedbacks are not strong enough to change the sign of the monsoon circulation anomalies. The direct influence of the El Niño/Southern Oscillation through the changes in Walker circulation appears to predominate."
"57193074351;6602311748;6603563453;","Remote sensing techniques adapted to high resolution mapping of tropical coastal marine ecosystems (coral reefs, seagrass beds and mangrove)",1998,"10.1080/014311698213858","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032458249&doi=10.1080%2f014311698213858&partnerID=40&md5=e415dc3a92b7c6b1da2c18c0414c70b1","The need for high resolution maps in the management of tropical environments is increasing and emphasized by the rapid anthropogenic development often occurring in coastal zones. In areas subject to humid tropical climate, such as the West Indies, cloud coverage often disturbs image acquisition by orbital imagery.Moreover, as thesetropical coastal ecosystems, i.e., coral reefs, mangroves and seagrass beds, are intricate and geographically complex, high resolution data must be used to accurately restore these features. Digitized aerial photographs meet these requirements by providing higher-resolution images than orbital remote sensing devices. This paper reports on the method applied to map coral reefs, mangroves and seagrass beds in the Bay of Robert in Martinique Island (French West Indies) by digitizing true-colour aerial photographs. But, as these photographs present two drawbacks, i.e., they are not geographically oriented and their margins are distorted, a reference map was used to design a rectification model. Aerial photographs were first subjected to true-colour digitization. After separation of the red, green and blue bands, an unsupervised classification was achieved, then various masks each corresponding to a given range of depths were built and applied to the initial image. The new images obtained were analysed. Great carewas taken in the selection oftraining sites to gather the pixels characterized by a high spectral similarity which corresponded to precise themes. After ground identification, these training sites enabled a supervized classification to be established, then a confusion matrix was built. The final map consisted of 31 themes. Each theme was related to a particular feature of the benthic communities. The error matrix and subsequent field samplings confirmed the reliability of the final map. In addition to their use in ecosystem studies, e.g., calculation of surface areas; biocoenosis distribution, etc., these thematic maps are of overriding importance for the management of coastal areas. © 1998 Taylor and Francis Group, LLC."
"6701664419;","Sound scattering from sea ice: Aspects relevant to ice-draft profiling by sonar",1998,"10.1175/1520-0426(1998)015<1023:SSFSIA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032452822&doi=10.1175%2f1520-0426%281998%29015%3c1023%3aSSFSIA%3e2.0.CO%3b2&partnerID=40&md5=acc63a71200d3728735c4820cb5f7551","Accurate discrimination between thin ice and open water using sonar is an important practical concern for the calibration of ice-draft observations and for the use of ice-profiling sonar in climate-related studies of sea ice. To guide improvement of the surface-detection algorithm used by this instrument, a narrowbeam 400-kHz sonar was used to record over 1 million surface echoes from pack ice in the Beaufort Sea during the winter of 1995-96. Large fluctuations in the amplitude of successive echoes were observed for all types of targets. The probability density of fluctuations had lognormal form, indicative of multiple-scattered incoherent returns for all targets, including calm ice-free water, uniform growing first-year ice, and ridge keels. Median values of the scattering coefficient ranged from -6.8 dB for calm water to -30 dB for thick level ice and ridge keels. These low values indicate that the surfaces of these targets appear very smooth to narrowbeam sonar at this frequency. Despite this, the detection of the much stronger specular returns was precluded by the narrow beam of the sonar. The use of echo amplitude for identifying open water is hindered by the absence of an abrupt change in the average backscattering coefficient when ice forms at the surface and by the wide range of random fluctuations in amplitude. Some capability to identify targets can be acquired by averaging the amplitude of successive echoes. However, the spatial scale at which averages become useful is larger than the dimension of the majority of the uniform targets present in pack ice. Errors in ice detection are caused by scattering from bubble clouds in stormy ice-free conditions. These can be reduced by careful selection of sonar characteristics, but not completely eliminated. Because of the wide variation in the strength of surface targets, it is recommended that ice-profiling sonars have a dynamic range of at least 60 dB, if the scattering strength of the target is to be determined."
"35558781400;7102916561;","Formation of a cold air lake during the warm season in a small hollow in Mt. Inako-dake, Yatsugatake Range",1998,"10.4157/grj1984a.71.8_559","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031739187&doi=10.4157%2fgrj1984a.71.8_559&partnerID=40&md5=44a3167602d7d7359ac57061a3fb1459","The present study focuses on the warm season temperature conditions in a small hollow of Mt. Inako-dake, Yatsugatake Range, central Japan, where an interesting vertical structure of vegetation is observed. Here, alpine plants (Pinus pumila community) are located at the bottom (ca. 2300 m a.s.l.) and a subalpine forest is formed above them (so-called vegetation inversion). An observational study was made of the frequency, intensity, and duration of the cold air lake during the warm season in order to reveal the climate environment related to the vertical structure of vegetation. Air temperature observations were carried out along the east-west section crossing the hollow from June 28 to November 7, 1995. A cold air lake was defined as that which has the maximum difference (referred to as 'maximum inversion' in this study) exceeding 2°C in night temperature between the summit of Mt. Inako-dake (the highest point; 2380 m) and the bottom of the hollow (the lowest point; 2230 m). Seventy-eight days were identified as having cold air lake formation. Cold air lake formation was substantially influenced by synoptic-scale pressure patterns. Cold air lakes were manifested when this area was under the influence of the North Pacific anticyclone during summer and the migratory anticyclone during autumn. Under the migratory high during autumn, the maximum inversion reached 19.5°C (October 13). Based on the synoptic pressure patterns, we categorized cold air lakes into two types: summer and autumn types that are formed under the North Pacific high and the migratory high, respectively. The summer and autumn types were identified for 19 days and 31 days, respectively. These types have respective average maximum inversions of 6.1°C and 8.7°C, and average periods of cold air lake formation of 6.3 hours and 8.7 hours, respectively. The cold air lakes of the summer type developed after midnight (23 h to 1 h), whereas those of the autumn type were formed earlier in the early evening (16 h) and maintained until morning (9 h). The radiative cooling that causes the cold air lakes of the summer type was likely weakened due to the increased downard long-wave radiation from clouds that persist until midnight and/or moist air. On the other hand, the dry air mass under the migratory high strengthened radiative cooling overnight for the autumn type."
"6701832491;6701915334;7402504552;6602484498;6603645136;","Simulation and validation of Arctic radiation and clouds in a regional climate model",1997,"10.1029/97jd02627","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031396594&doi=10.1029%2f97jd02627&partnerID=40&md5=e8daf751c2e122d006bc1bc45e910f17","A regional atmospheric climate model has been applied to simulate the Arctic climate north of 65°N at a 50 km horizontal resolution For January and July 1990. The monthly mean components of the surface radiative balance and clouds using ECHAM3 parameterization have been described and compared with data. The model overestimates the incoming shortwave flux, overestimates clouds during January, and underestimates clouds during July. The high-resolution simulations show many regional details due to regionally different surface temperatures, clouds, surface albedo, and snow depths. The bias in the model simulation can be reduced by using the ECHAM4 parameterization. The use of the ECHAM4 radiation parameterization clearly improves the results, due to the better description of atmospheric absorption. Sensitivity experiments with different cloud parameters (drop size, droplet concentration, cloud phase) have been described. The simulated changes due to these cloud parameter changes occur in a very small spatial scale and are of similar order as the model bias itself."
"7409080503;56132929700;57196608925;7401516897;10239032800;","Monitoring fire activities in the boreal ecosystem",1997,"10.1029/97jd01106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031462771&doi=10.1029%2f97jd01106&partnerID=40&md5=af7a126f5cfdc2cf60301f3cf7ae9222","Forest fire is a major disturbance to the boreal ecosystem and may interact with climate change. Unfortunately, we have relatively little knowledge regarding fire activities in the boreal ecosystem. This study investigates the extent and dynamics of the forest fires occurred in and around the Boreal Ecosystem-Atmosphere Study (BOREAS) region during summer 1994, an active fire season on record. The statistics of fire activities were obtained from advanced very high resolution radiometer (AVHRR) (aboard NOAA 11) data employing two satellite-based remote sensing techniques that were designed particularly for monitoring boreal forest fires. Active fires and burned area are estimated using single-day images and 10-day clear composites. Such basic fire attributes as the area and period of burning extracted from the satellite data are compared against the ground reports made by the fire management agencies in Saskatchewan and Manitoba, Canada. Overall, there were 99 fires of a total burning area of approximately 2 million ha found over an area of 800 × 700 km2 around the BOREAS study region in summer 1994. Agreement in the area of burning is good between the surface observations and satellite-based estimation using single-day images but poor using the composite data that suffer from various uncertainties. The majority (87%) of the ground-reported fires were detected by satellite; the satellite also identified some fires missed by the ground observers. Most fires in 1994 occurred in the transitional forest to the north and northwest of the BOREAS region. Regarding to the monitoring of fire evolution, the daily satellite detection approach can be as effective as or even more effective than ground observations, provided that cloud cover does not occur persistently. The smoke of the fires had an impact on some BOREAS flux measurements."
"7202969738;7408612236;7403129512;6701650122;","Modeling the impact of averaging on aggregation of surface fluxes over BOREAS",1997,"10.1029/97jd00456","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031448665&doi=10.1029%2f97jd00456&partnerID=40&md5=c1cfba19fe8cacf66f575c20cb58666c","Surface meteorological observations, soil and vegetation parameters, and satellite-retrieved surface radiation fluxes are used as input to a biosphere-atmosphere flux exchange model to estimate the fine-scale surface fluxes over a 75,000 km2 region within the large-scale BOREAS study area under cloud-free conditions. The size of the study area chosen for the analysis is synonymous with the characteristic grid size of a modern global climate model. The variables used to force the model are area-averaged and applied in such a fashion to assess the errors in area-wide fluxes that would arise in flux aggregation schemes based on the area-averaged inputs. In the absence of large spatial variance of downwelling radiative fluxes, characteristic of the clear sky case under study, progressive area averaging of the input parameters indicates that the most important quantities influencing the aggregated fluxes are root layer depth, soil moisture, and soil type, all of which are interrelated in the formulation of the transpiration capacity. Meteorological variance over the site and variability in a number of other parameters relating to vegetation characteristics and initial soil temperatures are not critical to the aggregation process. Notably, major errors in aggregated surface fluxes arise due to area-averaging soil moisture alone, even when all other parameters are not area-averaged and allowed to maintain their spatial variability. The errors materialize as significant phase shifts in the frequency distributions of the fine-scale surface fluxes calculated after input averaging. Application of a soil mosaic averaging technique, based on soil type and the soil moisture associated with each soil type, restores the characteristic mean values of the baseline area-averaged fluxes. This procedure also simplifies the surface flux distributions to dependence on the percentages of grid area covered by each soil type but without altering the basic multimodal character of the baseline distributions. It is demonstrated and explained why such a soil-type designation over the area forms the kernels for the surface flux distribution spectrums, around which the other input parameters act to disperse the frequency distribution properties of the aggregated surface fluxes."
"6603749963;7003927831;7003777747;9636594900;7003614389;6506762433;7003470046;7004942632;","Effects of anthropogenic emissions on tropospheric ozone and its radiative forcing",1997,"10.1029/97jd02226","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001058501&doi=10.1029%2f97jd02226&partnerID=40&md5=cbb896979672699a6e5d1a7688956acb","Tropospheric ozone changes since preindustrial times due to changes in emissions have been calculated by the University of Oslo global three-dimensional photochemical model. The radiative forcing caused by the increase in ozone has been calculated by two independent radiative transfer models; the University of Reading model (Reading), and the University of Oslo/Norwegian Institute for Air Research model (OsloRad). Significant increases in upper tropospheric ozone concentrations are found at northern midlatitudes (15-40 ppbv, depending on season) at about 10 km altitude. In the tropical regions the largest increase (about 20 ppbv for all seasons) is found at about 15 km altitude. The increase is found to be caused mainly by enhanced in situ production due to transport of precursors from the boundary layer, with a smaller contribution from increased transport of ozone produced in the boundary layer. The lifetime of ozone in the troposphere decreased by about 35% as a result of enhanced concentrations of HO2. The calculated increase in surface ozone in Europe is found to be in good agreement with observations. The calculations of radiative forcing include the effect of clouds and allow for thermal adjustment in the stratosphere. The global and annual averaged radiative forcing at the tropopause from both models (0.28 W m-2 and 0.31 W m-2, for the Reading and OsloRad models, respectively) are in the lower part of the Intergovernmental Panel on Climate Change [1995] estimated range. The calculated radiative forcing is similar in magnitude to the negative radiative forcing by sulfate aerosols, but displaced southward in source regions at northern midlatitudes. The increase in tropospheric ozone is calculated to have cooled the lower stratosphere by up to 0.9 K, with possibly half of this cooling occurring in the past 2 to 3 decades."
"6603968676;35446498700;7405728922;","On the measurements of cloud condensation nuclei at Palmer Station, Antarctica",1997,"10.1016/S1352-2310(97)00250-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031543370&doi=10.1016%2fS1352-2310%2897%2900250-1&partnerID=40&md5=c7f5e99716d33c3ee71f7bede687b874","The predominant characteristics associated with a first dataset of daily daylight period averaged cloud condensation nuclei (CNN) spectral measurements at a remote region of the globe, namely Palmer Station, Antarctica, are discussed. Palmer Station is located on the Antarctic Peninsula and sits on a glacial moraine between the Piedmont glacier and the Bellings-Hausen Sea in the midst of natural Antarctic sources, which could include sea-to-air emission of marine organic nuclei. The predominant local pollution source is a diesel power plant approximately 100 m WNW of the sampling platform."
"7004993886;7005634455;6603031108;","Evaluating moist physics for Antarctic mesoscale simulations",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-4143114937&partnerID=40&md5=1bfff1ba2df5bf48b81b1ac81b6a4fdb","The performance of an explicit cloud physics parameterization is examined with simulations of high southern latitude winter climate using a version of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model, version 4. The results reveal that there are three moist physics regimes in the vertical over the elevated interior of Antarctica: the very cold upper troposphere, the relatively warm middle troposphere and the cold boundary layer. Deficiencies for these layers include excessive cloud ice in the upper troposphere, excessive cloud ice in the inversion layer near the ice surface, overly warm temperatures in the lower troposphere, overly cold temperatures in the upper troposphere and excessive downward longwave radiation at the Earth's surface. Three sensitivity experiments were performed to investigate possible improvements in the cloud parameterization. The results indicate that a reduction of the numerous cloud condensation nuclei, while reducing some errors, appears to be insufficient to improve the simulation. A reduction in the excessive cloud ice in the upper troposphere significantly improves the simulation of upper-tropospheric temperature."
"6507285356;6506434115;","Observation of a rare 'spoked-wheel' lightning phenomenon in the French Alps",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031410408&partnerID=40&md5=5067129797a26a1d5f445c83a9cc449f","In the Chablais region of the French Alps, the unusual observation of a series of rotating, 12- to 16- spoked wheels of lightning with two outer rings of striations which moved across the sky within the base of a storm cloud on 6 September 1997 is described."
"12645090400;","The conversion of ATSR sea surface temperatures for use in a climate database",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-5244327572&partnerID=40&md5=6e41ff833bed7a6eff33f7f3b5c85015","The high accuracy of 'skin' sea surface temperature (SST) measurements from ATSR make them a valuable source for global databases used in climate studies. To compliment existing records measured from ships and buoys, it is necessary to convert the observations to a bulk SST at a depth of about 1 metre. A method is being developed to do this at the United Kingdom Meteorological Office (UKMO), which includes quality control tests to reject observations with cloud and aerosol contamination. Skin to bulk SST models are currently being tested using meteorological data from the UKMO's Global Model. The predictions from the models are compared with drifting buoy temperature measurements, with the aim of developing the best conversion for different surface windspeed regimes under different solar radiation conditions. This paper will review the skin vs bulk SST issues, will show the necessity for full quality control of the satellite data, and will show results from the latest conversion models."
"7006479635;6603061242;7401449985;7005961819;35463166700;","HCHO, HCOOH and CH3COOH in air and rain water at a rural tropical site in north central India",1997,"10.1016/S1352-2310(97)00263-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031543545&doi=10.1016%2fS1352-2310%2897%2900263-X&partnerID=40&md5=cd14df3fed748d9931f22f4b3bde2984","HCHO, HCOOH and CH3COOH were measured in vapour phase and rainwater during monsoon period at Gopalpura, Agra a rural site of north central semi-arid tract of India. Mean concentrations of formaldehyde, formic and acetic acids were 1.4, 1.7 and 1.6 ppbv in the vapour phase and were 4.4, 5.4 and 4.8 μmol l-1 (volume weighted) in rain water, respectively. Due to cloud cover and rain which occurs intermittently in monsoon these species did not show typical diurnal pattern as reported by others. In the gas phase a good correlation of formic acid with acetic acid (r = 0.78)and poor correlation with formaldehyde (r = 0.19) suggested that formic and acetic acids may also have significant contributions from other than photochemical sources such as biogenic sources. The strong correlation between formate and acetate (r = 0.96) and formate and formaldehyde (r = 0.95) in rain water suggests that their sources are common, if not identical. Regression analysis between concentration vs precipitation volume and deposition amount vs precipitation volume of the three species suggested that concentration of these species are almost independent of rain volume and controlled by a continuous supply of these species by slowly scavenged material or oxidation of aldehyde to organic acid. HCOO-/HCHO ratio (1.4) also suggested that aqueous-phase oxidation of formaldehyde is a major source of formic acid in rain water.HCHO, HCOOH and CH3COOH were measured in vapour phase and rain water during monsoon period at Gopalpura, Agra a rural site of north central semi-arid tract of India. Mean concentrations of formaldehyde, formic and acetic acids were 1.4, 1.7 and 1.6 ppbv in the vapour phase and were 4.4, 5.4 and 4.8 μmol l-1 (volume weighted) in rain water, respectively. Due to cloud cover and rain which occurs intermittently in monsoon these species did not show typical diurnal pattern as reported by others. In the gas phase a good correlation of formic acid with acetic acid (r = 0.78) and poor correlation with formaldehyde (r = 0.19) suggested that formic and acetic acids may also have significant contributions from other than photochemical sources such as biogenic sources. The strong correlation between formate and acetate (r = 0.96) and formate and formaldehyde (r = 0.95) in rain water suggests that their sources are common, if not identical. Regression analysis between concentration vs precipitation volume and deposition amount vs precipitation volume of the three species suggested that concentration of these species are almost independent of rain volume and controlled by a continuous supply of these species by slowly scavenged material or oxidation of aldehyde to organic acid. HCOO-HCHO ratio (1.4) also suggested that aqueous-phase oxidation of formaldehyde is a major source of formic acid in rain water."
"7003327761;35446498700;","Impact of air mass histories on the chemical climate of Mount Mitchell, North Carolina",1997,"10.1029/97jd01183","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031427535&doi=10.1029%2f97jd01183&partnerID=40&md5=5d22e63b022904e97549e203685871e5","Cloud water acidity and ionic content, as measured at the Mount Mitchell (35°44′05″N, 82°17′15″W, 2038 m msl (highest peak in the eastern United States)) State Park observing site, using a passive cloud water collector, are directly influenced by the trajectories of cloud-forming air masses which pass over areas of varying levels of pollutant emission. Regions of the United States which are emitters of high-level pollutants, such as SOx and NOx' will thus serve to reduce observed pH levels in cloud water samples and raise the levels of acidifying ions, such as sulfate and nitrate. The 48-hour backward trajectories for all 39 cloud events during the 1993 field season (May 15, 1993 to October 14, 1993) were computed using the hybrid single-particle Lagrangian integrated trajectories (HY-SPLIT) model. Three sectors, identified as the polluted sector, from 290° to 65° azimuth relative to the site, the continental sector, 240° to 290° azimuth, and the marine sector, 65° to 240° azimuth, were used to classify the cloud-forming air masses. The polluted sector was associated with the lowest overall pH averages, with the marine sector following closely behind. The highest average pH values were received from air masses indicated as having crossed the continental and the marine sectors (in combination), with the largest portions of those air mass trajectories passing through the continental sector (exclusively continental sector air masses were also the most frequent). These observations are in agreement with findings in Colorado where aerosols produced by wind erosion were responsible for decreasing the precipitation acidity."
"7202505945;","The maximum potential intensity of tropical cyclones",1997,"10.1175/1520-0469(1997)054<2519:TMPIOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031395098&doi=10.1175%2f1520-0469%281997%29054%3c2519%3aTMPIOT%3e2.0.CO%3b2&partnerID=40&md5=eef897ee0ab50c5324864375f4743604","A thermodynamic approach to estimating maximum potential intensity (MPI) of tropical cyclones is described and compared with observations and previous studies. The approach requires an atmospheric temperature sounding, SST, and surface pressure; includes the oceanic feedback of increasing moist entropy associated with falling surface pressure over a steady SST; and explicitly incorporates a cloudy eyewall and a clear eye. Energetically consistent, analytic solutions exist for all known atmospheric conditions. The method is straightforward to apply and is applicable to operational analyses and numerical model forecasts, including climate model simulations. The derived MPI is highly sensitive to the surface relative humidity under the eyewall, to the height of the warm core, and to transient changes of ocean surface temperature. The role of the ocean is to initially contribute to the establishment of the ambient environment suitable for cyclone development, then to provide the additional energy required for development of an intense cyclone. The major limiting factor on cyclone intensity is the height and amplitude of the warm core that can develop; this is closely linked to the height to which eyewall clouds can reach, which is related to the level of moist entropy that can be achieved from ocean interactions under the eyewall. Moist ascent provides almost all the warming above 200 hPa throughout the cyclone core, including the eye, where warm temperatures are derived by inward advection and detrainment mixing from the eyewall. The clear eye contributes roughly half the total warming below 300 hPa and produces a less intense cyclone than could be achieved by purely saturated moist processes. There are necessarily several simplifications incorporated to arrive at a tractable solution, the consequences of which are discussed in detail. Nevertheless, application of the method indicates very close agreement with observations. For SST &lt; 26°C there is generally insufficient energy for development. From 26° to 28°C SST the ambient atmosphere warms sharply in the lower troposphere and cools near the tropopause, but with little change in midlevels. The result is a rapid increase of MPI of about 30 hPa °C-1. At higher SST, the atmospheric destabilization ceases and the rate of increase of MPI is reduced."
"7007152721;","Heat island development in Mexico City",1997,"10.1016/S1352-2310(97)00136-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031282649&doi=10.1016%2fS1352-2310%2897%2900136-2&partnerID=40&md5=9b8a91637fb90a51baf4e6b8a6736817","The present paper describes the climatology of the near surface urban heat island of Mexico City, using hourly data from two recently installed automatic stations at a rural and an urban site. The results show that the nocturnal heat island was more frequent (75% of the time for the period examined) than daytime cases (25%). The maximum nocturnal heat island intensity, 7.8°C was observed in a dry month (February) characterized by calm clear nights. Although less frequent, the daytime heat islands did occur and may have been caused by differences in evaporative cooling from wet surface during the wet season. Midday heat islands had a frequency of 13% and an intensity of 3-5°C during the wet season. The afternoon/evening heat islands had an intensity of 4-5°C. They occurred during both dry and wet season with a frequency of 12% of the time in a year. The average urban/rural thermal contrasts are positive throughout the year varying from 5°C at day break in the middle of the dry season to 1-3°C around noon during the wet months.The present paper describes the climatology of the near surface urban heat island of Mexico City, using hourly data from two recently installed automatic stations at a rural and an urban site. The results show that the nocturnal heat island was more frequent (75% of the time for the period examined) than daytime cases (25%). The maximum nocturnal heat island intensity, 7.8 °C was observed in a dry month (February) characterized by calm clear nights. Although less frequent, the daytime heat islands did occur and may have been caused by differences in evaporative cooling from wet surface during the wet season. Midday heat islands had a frequency of 13% and an intensity of 3-5 °C during the wet season. The afternoon/evening heat islands had an intensity of 4-5 °C. They occurred during both dry and wet season with a frequency of 12% of the time in a year. The average urban/rural thermal contrasts are positive throughout the year varying from 5 °C at day break in the middle of the dry season to 1-3 °C around noon during the wet months."
"55454298000;7005968859;55739897500;","The effects of clouds on aerosol and chemical species production and distribution 1. Cloud model formulation, mixing, and detrainment",1997,"10.1029/97jd01523","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1642554072&doi=10.1029%2f97jd01523&partnerID=40&md5=4660a06c8a975921912c8cf2a3331a46","Clouds play an important role in tropospheric chemical processes and in the modulation of global climate via transport of reactive species from lower levels of the troposphere to higher altitudes and by modification of boundary layer gas and aerosol concentrations by aqueous phase reactions in cloud and precipitation. We present here the initial results of a study of the effects of deep convective clouds upon transport of aerosols and aerosol precursor gases along with a discussion of the formulation of the two-dimensional Eulerian model dynamics and two-moment bulk microphysics parameterization. Results from a test run using data from the Cooperative Convective and Precipitation Experiment show reasonable agreement with observations, although comparison with aircraft observations show the model cannot resolve saturated downdrafts. Comparison with the Taylor and Baker [1991] detrainment criterion shows good agreement for water vapor, a passive tracer, and cloud condensation nuclei."
"6603400519;7005513582;","Sensitivity of climate simulations to radiative effects of tropical anvil structure",1997,"10.1029/97jd02009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0043035566&doi=10.1029%2f97jd02009&partnerID=40&md5=08cf9bbd72c7502b2d46913aaf4df7e9","Climate sensitivity to the representation of tropical anvil is investigated in a version of the National Center for Atmospheric Research Community Climate Model. Common features of tropical anvil generation and structure, consistent with observations and cloud resolving models, are incorporated into a simple prognostic anvil parameterization. These features include anvil convective origin, vertical profile, phase, areal extent, and life span. Two numerical climate integrations are forced by 1985-1989 sea surface temperature (SST): the control, with simple diagnostic anvil, and the experiment, which simulates tropical anvil structure prognostically. The prognostic anvil formulation enhances ice and reduces liquid in the tropics. Increase in hydrometeor size associated with anvil weakens cloud radiative extinction per unit mass by factors of 1-3. The weaker mass extinction efficiency approximately balances enhanced ice amount so that anvil ice mass quadruples without biasing the mean radiative energy balance but significantly alters the vertical distribution of radiative effects. Enhanced anvil perturbs the tropical upper troposphere temperature structure more strongly in winter, when the column is clearer and anvil radiatively heats the troposphere above 200 mbar. In the summer tropics, enhanced anvil reduces radiative cooling up to 200 mbar and enhances cooling above that. The prognostic anvil formulation improves longwave cloud radiative response to SST cooling but worsens response to warming >2°C. The net response of convection is a shift toward the winter hemisphere in solstice months. These changes lead to a significant response in the extratropical height field in January. These results emphasize the importance of representing tropical anvil structure in climate simulations."
"6506634244;7004222759;","Latitudinal UVR-PAR measurements in Argentina: Extent of the 'ozone hole'",1997,"10.1016/S0921-8181(97)00007-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030697085&doi=10.1016%2fS0921-8181%2897%2900007-6&partnerID=40&md5=2cab25b13e8349d1ddeec6254a65738b","The UVR-PAR Argentinean Monitoring Network started its operation in September 1994 recording ultraviolet (UVR) and Photosynthetic Available Radiation (PAR) at a frequency of once per minute, at four sites, throughout the entire year. Four spectroradiometers (GUV-511, Biospherical Instruments, Inc.) were installed at research centers separated by about 8-12 degrees of latitude, extending from the Subantarctic-Fueguian region to the Tropic of Capricorn. The instruments are located in populated areas ranging from 30.000 to 11 million people and with extremely different climate regimes and conditions of tropospheric pollution. Our ground-based data indicated that the irradiance increased steadily from south to north. This increase was also observed in the calculated daily doses of UV-B (280-320 nm); however, daily integrated values for UV-A (320-400 nm) and PAR (400-700 nm) were higher at mid-latitudes (Puerto Madryn, 42°47'S). A similar south-to-north increase was evident in the ratio of the energy at 305 nm and 340 nm wavelengths (with low 305/340 ratios indicating high total ozone column concentration), with low values at Ushuaia (55°01'S) and high values at Jujuy (24°10'S). However the 305/340 ratios increased significantly over their normal spring values at two s res Ushuaia and Puerto Madryn, for variable me periods during October-December. Our data suggest that the ozone hole was over South America extending to about 38°S for at least a week during October and about two weeks during November-December of the years of 1994 and 1995. However, it should be noted that the erythemal irradiance, in the area influenced by the ozone hole, was at all times lower than that in Buenos Aires and well below the value at Jojuy (tropical station). This study also indicates that when assessing the impact of solar UVR upon organisms, other variables such as cloud cover, solar zenith angle, day length, latitude, and atmospheric pollution should be considered in addition to total ozone column concentration."
"7103271625;6603171355;7003543851;6701618837;36950338700;7102862273;7102018821;","Large-scale ice clouds in the GFDL SKYHI general circulation model",1997,"10.1029/97jd01488","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031391549&doi=10.1029%2f97jd01488&partnerID=40&md5=d0c4496154345f043ad09b0820bc5442","Ice clouds associated with large-scale atmospheric processes are studied using the SKYHI general circulation model (GCM) and parameterizations for their microphysical and radiative properties. The ice source is deposition from vapor, and the ice sinks are gravitational settling and sublimation. Effective particle sizes for ice distributions are related empirically to temperature. Radiative properties are evaluated as functions of ice path and effective size using approximations to detailed radiative-transfer solutions (Mie theory and geometric ray tracing). The distributions of atmospheric ice and their impact on climate and climate sensitivity are evaluated by integrating the SKYHI GCM (developed at the Geophysical Fluid Dynamics Laboratory) for six model months. Most of the major climatological cirrus regions revealed by satellite observations appear in the GCM. The radiative forcing associated with ice clouds acts to warm the Earth-atmosphere system. Relative to a SKYHI integration without these clouds, zonally averaged temperatures are warmer in the upper tropical troposphere with ice clouds. The presence of ice produced small net changes in the sensitivity of SKYHI climate to radiative perturbations, but this represents an intricate balance among changes in clear-, cloud-, solar-, and longwave-sensitivity components. Deficiencies in the representation of ice clouds are identified as results of biases in the large-scale GCM fields which drive the parameterization and neglect of subgrid variations in these fields, as well as parameterization simplifications of complex microphysical and radiative processes."
"7402456930;","Variations in western Arctic temperatures in response to cloud radiative and synoptic-scale influences",1997,"10.1029/97jd01840","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031393005&doi=10.1029%2f97jd01840&partnerID=40&md5=43994dddf29c28e0e3e87203d1a2e976","The analysis focuses on Barrow, Alaska, a site that is sensitive to changing conditions because it is located near cryospheric boundaries and is influenced by both extratropical and Arctic synoptic activity. Surface and upper air meteorological data for a 31-year period (1965-1995) are used to evaluate temperature variations as they relate to dynamical and radiative processes. Both annual and monthly analyses indicate a tendency toward warming overall. However, the annual warming is not monotonic over time and varies seasonally. Comparisons of temperature time series from four sites along the Siberian-Alaskan coastline show that Barrow is a representative site to evaluate climate change in the western Arctic coastal zone. Regionally, the warming is dominated by significant temperature increases during winter and spring, but cooling is indicated for autumn. These results are not entirely consistent with model predictions of a more uniform high-latitude warming during the cold season in response to increasing concentrations of greenhouse gases in the atmosphere. Rather, the observed changes are attributed to well-known natural processes that affect regional cloud distributions in response to changing circulation patterns. Coincident daily and hourly meteorological and radiation data are also used to demonstrate empirically how clouds modulate Arctic temperatures."
"36000595000;7005968859;7102604282;56222822400;","Potential origin of organic cloud condensation nuclei observed at marine site",1997,"10.1029/97jd01554","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031415077&doi=10.1029%2f97jd01554&partnerID=40&md5=89f381721fb275ab5bd51d47df0592d1","Observations by Novakov and Penner [1993] (hereinafter, NP) suggest that organic aerosol particles may make up a significant portion of cloud condensation nuclei (CCN), comparable perhaps to the sulfate aerosol contribution to CCN. Because organic CCN would influence the albedo and radiative properties of clouds and play a role in climate change, it is important to identify the sources of these aerosols. In their research, Novakov and Penner showed that particles larger than 0.05 μm could act as CCN at supersaturation ratios of 0.5% water vapor. Here we use model simulations to investigate the origins of the nucleation mode aerosol (0.03 &lt; dp &lt; 0.1 μm) observed at a marine site in Puerto Rico by NP. NP measured the size segregated mass and composition of the atmospheric aerosol at this site and found that organic aerosol mass dominated the total mass in the nucleation mode. The presence of organics in this size range may be the result of nucleation of a gas phase organic and/or condensational growth. Therefore identifying sources of the gas phase precursors is important to determining the origins of the organic CCN. Back trajectory analysis (J. Merrill, private communication, 1994) shows that the air mass that Novakov and Penner studied was without continental contact for 8-12 days prior to being sampled. This implicates two possible sources for the gas phase organic: biogenic emissions from the Puerto Rican forest upwind of the mountain sampling site and emissions from the ocean surface. In this study both the forest and ocean source scenarios are explored. Using input parameters taken from the literature, it is shown that an assumed organic vapor flux for the forest scenario, very similar to the measured biogenic fluxes reported by Zimmerman et al. [1988], generated size distributions similar to the observed aerosol. In contrast, literature estimates for the n-alkane vapor flux from the ocean are not consistent with the observed size distribution at the mountain site."
"57206029166;13406672500;","Lagrangian approach for deriving cloud characteristics from satellite observations and its implications to cloud parameterization",1997,"10.1029/97jd00930","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031413306&doi=10.1029%2f97jd00930&partnerID=40&md5=de1ce28353840f38d110ad325031ef7d","A Lagrangian view is adopted for establishing the spatiotemporal cloud statistics and the scale dependent radiative properties using satellite data. Individual clouds are identified using a newly developed scheme. We sort all clouds by cloud type, cloud area, and number of clouds in each area bin, as well as their radiative properties. For seven different cloud types our analyses provide radiative properties, such as albedo and cloud top temperature, as a function of the cloud spatial scale. All clouds are marked by local time, and large clouds are tracked over time. These analyses provide diurnal variability, lifetimes, and evolution of cloud systems as a function of their spatial scales. These scale dependent cloud properties can be objectively used in guiding the development and evaluation of cloud parameterization in global climate models (GCMs). Particularly, we show how our Lagrangian approach can be used to establish the relative importance of resolvable and fully parameterized clouds to the total cloudy area and to the total amount of reflected visible irradiance. Focus in this 1 month satellite study is on the convective-stratiform cloud systems over the western and central tropical Pacific Ocean, including the so-called warm pool. We adopt the hourly Japanese geostationary satellite (GMS) window channel radiances in the visible and IR window region for cloud classification and characterization. To study the radiative contributions of different clouds in the area, we computed the bidirectional model (BDM) for the Visible and Infrared Spin Scan Radiometer instrument aboard GMS, which we show to agree well with the BDM of the Earth Radiation Budget instrument aboard the Nimbus 7 satellite. An iterative two-stage cloud detection scheme was developed to identify individual clouds. Furthermore, a tracking algorithm was developed to study the time evolution of mesoscale convective systems (MCS). It operates on area and orientationally equivalent ellipsoidal representations of these MCS. We show that the temporal statistics of these convective anvil clouds show good agreement with those reported in the literature. Our data indicate that for the convective-stratiform systems in the tropical Pacific, 95% of the radiatively important clouds (containing a core with an effective brightness temperature <219 K) are of scales resolvable by a GCM of about 50 km × 50 km. On the other hand, a GCM of 250 km × 250 km will only be able to resolve 50% of the radiatively important clouds. This, however, does not mean that the processes responsible for the formation and maintenance of these systems are also resolvable. The low clouds that are unattached to convective-stratiform systems are mostly unresolvable by available GCMs."
"7006167299;7005858285;7102604282;7201496259;6602994894;6602765265;","Organic aerosols in the Caribbean trade winds: A natural source?",1997,"10.1029/97jd01487","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031425331&doi=10.1029%2f97jd01487&partnerID=40&md5=5668ba9fae8972e838f50c30366628d1","Mass concentrations of carbonaceous and inorganic components of submicron (aerodynamic diameters &lt; 0.6 μm) aerosol particles were measured at Cape San Juan, a coastal site located on the extreme northeastern tip of Puerto Rico. Additionally, carbonaceous aerosols and condensation nuclei (CN) were measured offshore during a limited shipboard sampling experiment at an Atlantic Ocean site away from the coast. Both sites were exposed to trade winds during the sampling periods. Under these conditions no obvious upwind anthropogenic sources should impact the sites. From the analyses of collected filter samples, mass concentrations of major inorganic anions and filterable particulate organic aerosol material (OCP) were determined. The derived OCP concentrations may represent lower limits because of the uncertainty in the collection of semivolatile organic material lost from the particles during sampling. Analyses of Cape San Juan samples show that (1) mass concentrations of submicron OCP (average about 390 ng m-3) exceed sulfate concentrations (average about 270 ng m-3); (2) this organic aerosol material is water soluble (and the particles act as effective cloud condensation nuclei); and (3) primary combustion aerosol does not appear to be a major contributor to OCP. The fact that OCP concentrations measured at the coastal site are similar to OCP concentrations (330 - 400 ng m-3) measured at an Atlantic Ocean site removed from the coast suggests that a substantial fraction of the OCP in the Caribbean trade winds may be associated with natural oceanic emissions. Results imply that background organic marine aerosol should be included in estimating the indirect forcing of climate by anthropogenic sulfate aerosol."
"55605773363;","A cumulus parameterization based on a cloud model of intermittently rising thermals",1997,"10.1175/1520-0469(1997)054<2292:ACPBOA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000382467&doi=10.1175%2f1520-0469%281997%29054%3c2292%3aACPBOA%3e2.0.CO%3b2&partnerID=40&md5=f5ce0be3e0b3bcb3a8c293bb963ca9e3","The author presents a cumulus parameterization that uses a cloud model that describes atmospheric convection as consisting of a sequence of intermittently rising thermals. The total mass of thermale in a convection event is determined by the amount of convective available potential energy in local soundings. In the cloud model, it is assumed that a thermal entrains environmental air only at a thin layer around the top frontier of its rising body. The entrained air mass mixes with the thermal's air and produces ""mixtures"" that then detach themselves from the thermal. This limited mixing prevents deep erosion to the thermal's buoyancy by entrainment and mixing processes. The remainder of the thermal continues rising to higher levels and forming more mixtures on its way to its own level of neutral buoyancy. The mixtures also rise or sink from the levels where they form to their level of neutral buoyancy. Evaluation of this scheme using Global Atmospheric Research Program Atlantic Tropical Experiment data shows that the parameterized convective heating and drying rates are consistent with observations. The calculated convective precipitation also shows a distribution similar to the observed total precipitation, except at the trough of the easterly waves where calculated precipitation is smaller than observed. The capability of this scheme in describing cumulus convection is further tested in a fully prognostic one-dimensional climate model. Results from this evaluation show reasonable climatological temperature and relative humidity profiles in the troposphere."
"7006131953;7801687660;","Microphysical factors that influence solar radiation transfer in the atmosphere",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031399689&partnerID=40&md5=c62102a3ad97b061c6ea6202f1b9d623","The effect of the continuous absorption by gases on solar radiation transfer is considered. The sensitivity of solar radiation calculations both to the shape of cloud scattering phase functions and to the type of spectroscopic database used in the calculations is discussed. The database of the benchmark calculations of solar fluxes intended to verify radiation codes of climate models is briefly described."
"7202315227;6506193023;10640183500;6506958013;7401926695;57198227434;6507465005;35582115100;7004898341;","Solubility of single chemical compounds from an atmospheric aerosol in pure water",1997,"10.1016/S1352-2310(97)00089-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031239218&doi=10.1016%2fS1352-2310%2897%2900089-7&partnerID=40&md5=f31ea2e8de4977775f5a7519659816f5","The water-solubility differentiates atmospheric particles into cloud condensation nuclei (CCN) and interstitial aerosol. This interaction between aerosol and cloud influences the climate in different known and hypothetical ways. Some authors studied the fraction of water-soluble amounts with particle size. As the water-solubility (or hygroscopicity) is a property of chemical compounds it is of great interest to identify the chemical composition of aerosols and of the dissolved fraction. Using an optimal combination of analytical methods, the elemental and species concentrations were determined in the original aerosol as well as in the resulting solutions. The fraction of soluble species were calculated from the measured values and three groups were found: with high (50-73%), medium (20-26%), and low (2%) dissolved fraction. In a further series of experiments the rate constants of dissolution of various species were determined. These can be arranged in the order of decreasing rate of dissolution: the alkaline and alkaline earth elements K+ ≃ Mg2+ &gt; NH4+ &gt; Na+ &gt; Ca2+, the anions NO3- ≃ SO42- ≃ Cl-, and for the iron oxidation states Fe(3+) &gt;&gt; Fe2+. A photolytic reduction of Fe3+ to Fe2+ was also observed. For Mg2+, Ca2+, and SO42- a dependance of the rate constants for dissolution on time was discovered. This can be explained by the presence of different chemical compounds in the aerosol. The discussion of the results with regard to the time scale of the formation of cloud or fog droplets shows that the slightly soluble inventory of a solid aerosol of the alkaline and alkaline earth elements, as well as of the anions, is dissolved into the aqueous phase in a relatively short time interval of 10-700 s. On the other hand, Fe3+ is dissolved in a time period of 3000-4500 s, whereas Fe2+ appears in the solution in a time period of up to 7000 s.The water-solubility differentiate atmospheric particles into cloud condensation nuclei and interstitial aerosol. Using an optimal combination of analytical methods, the analytical and species concentrations in atmospheric aerosols and in the dissolved fraction as well as the rate constants of dissolution were determined. Arranged in decreasing dissolution rate, the following species were identified: K+, Mg2+, NH4+, Na+, Ca2+, NO3-, SO42-, Cl-, Fe3+ and Fe2+. The slightly soluble inventory of a solid aerosol of the alkaline and alkaline earth elements, as well as of the anions, was dissolved into the aqueous phase in a relatively short interval of 10-700 s, while the dissolution of Fe3+ occurred in 3000-4500 s, whereas Fe3+ was in solution for a maximum 7000 s."
"7005751636;7201453095;6603856922;7007048153;23112636200;","Seasonal and spatial characteristics of formic and acetic acids concentrations in the Southern California atmosphere",1997,"10.1021/es960954i","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031239683&doi=10.1021%2fes960954i&partnerID=40&md5=e88b7c939c2b6c5277b96a2b6f078278","Formic and acetic acids measurements made during the year 1986 are reported for eight sites in the Los Angeles basin and one remote offshore site. Formic and acetic acids concentrations measured in marine air upwind of the Los Angeles area over an 8-month period average 1.4 and 0.6 ppb, respectively, while concentrations within the Los Angeles urban area average 2.7-5.8 ppb formic acid and 2.9-4.2 ppb acetic acid. Average formic and acetic acids concentrations exceed average HN03 and HCl concentrations, making them the most abundant gas phase acids in the southern California atmosphere throughout the year. Formic and acetic acids concentrations near the coast change in proportion to changes in atmospheric dilution potential, as would be expected if formic and acetic acids were emitted directly from widespread area sources such as motor vehicle traffic. Downwind of Los Angeles, formic and acetic acids concentrations peak during the summer photochemical smog season, and concentration changes track both changes in atmospheric oxidant concentrations and markers for heterogeneous conversion within clouds or fog. Formic and acetic acids concentrations thus appear to arise both from direct emissions and from atmospheric chemical production, with the relative importance of these pathways varying spatially over the area surveyed.Formic and acetic acids measurements made during the year 1986 are reported for eight sites in the Los Angeles basin and one remote offshore site. Formic and acetic acids concentrations measured in marine air upwind of the Los Angeles area over an 8-month period average 1.4 and 0.6 ppb, respectively, while concentrations within the Los Angeles urban area average 2.7-5.8 ppb formic acid and 2.9-4.2 ppb acetic acid. Average formic and acetic acids concentrations exceed average HNO3 and HCl concentrations, making them the most abundant gas phase acids in the southern California atmosphere throughout the year. Formic and acetic acids concentrations near the coast change in proportion to changes in atmospheric dilution potential, as would be expected if formic and acetic acids were emitted directly from widespread area sources such as motor vehicle traffic. Downwind of Los Angeles, formic and acetic acids concentrations peak during the summer photochemical smog season, and concentration changes track both changes in atmospheric oxidant concentrations and markers for heterogeneous conversion within clouds or fog. Formic and acetic acids concentrations thus appear to arise both from direct emissions and from atmospheric chemical production, with the relative importance of these pathways varying spatially over the area surveyed."
"57212781009;6701715507;","A study of general circulation model climate feedbacks determined from perturbed sea surface temperature experiments",1997,"10.1029/97jd00206","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031401050&doi=10.1029%2f97jd00206&partnerID=40&md5=2451d44cd1b968c37312a05fcfd5e0d2","The response of a general circulation model (GCM) to global perturbations in sea surface temperatures (SSTs) is examined. The feedback strengths in the model are diagnosed by the response of top of atmosphere (TOA) radiative fluxes determined after substitution of fields from the ""perturbed"" climate into the ""control."" Total feedback is divided into terms due to water vapour, lapse rate, surface temperature, and clouds (in turn analysed in terms of cloud amount, height and types). The ""standard experiment"" prescribes a globally uniform SST perturbation with fixed soil moisture. Four additional experiments vary the number of model vertical levels, the pattern of SST changes, the convection scheme, and the soil moisture. The SST pattern change chosen follows that of an equilibrium 2×CO2 experiment, which shows polar amplification of the surface warming. Variations in the clear sky sensitivity of the model are shown to depend primarily on changes in the long wave response due to competing (positive) water vapor and (generally negative) lapse rate feedbacks. Results here indicate that these feedbacks may be very different for differing experimental boundary conditions. The long wave feedback due to cloud amount changes is negative in all experiments, due to a very consistent decrease in high and middle cloud fractions. Conversely, cloud height feedback is positive due to a general increase in the altitude of (particularly high) cloud. Cloud height feedback is very sensitive to the choice of the convection scheme and to the change in vertical resolution. Greatest changes in the strength of the short wave cloud feedback results from modifications to the soil moisture specification and the convection scheme. The results here indicate that large differences in cloud feedback may be diagnosed from a single model, even without changes being made to the cloud parametrization. The value of the sensitivity can thus be expected to be a function not only of the physical parametrizations chosen for the model (e.g. the penetrative convection scheme), but also of the details of the manner in which the experiment was performed (e.g. SST and soil moisture specifications). The TOA radiation perturbation analysis method proves to be a powerful technique for diagnosing and understanding the physical processes responsible for the range in climate sensitivity found between the experiments."
"57192688381;55640270800;6601950693;7004942632;7102358724;","Radiative forcing of climate change by CFC-11 and possible CFC replacements",1997,"10.1029/97jd01137","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000325725&doi=10.1029%2f97jd01137&partnerID=40&md5=c5cc9f39afd08de5e45157978d430f62","The infrared absorption cross sections of CFC-11 and 16 other halogenated compounds have been measured. These spectra were used in detailed line-by-line calculations to derive radiative forcing values. The radiative forcing values for 14 of these gases have not, to our knowledge, been previously reported in the literature. The accuracy of a computationally inexpensive narrowband scheme, which included the effect of clouds and stratospheric adjustment, was investigated. Global warming potentials are presented where atmospheric lifetimes are available. In light of the substantial disagreement in values for the forcing due to CFC-11 reported in the literature and its use as a standard to which other halogenated gases are often compared, we examined the sensitivity of CFC-11 forcing to a number of assumptions. We find that the uncertainties in the calculated value of the radiative forcing caused by neglect of the temperature and pressure dependence of the IR absorption spectrum are much smaller than those resulting from uncertainties in the absolute absorption cross sections or the vertical profile of CFC-11. Our best estimate is 0.285 W m-2 ppbv-1, which is 30% higher than the value adopted by the Intergovernmental Panel on Climate Change and is believed to be accurate to within about 10%. For the other gases represented here the lack of detailed knowledge of the likely vertical and horizontal distribution probably represents the most significant uncertainty in evaluating their radiative forcing."
"7003904922;","Do effects of global atmospheric electricity on clouds cause climate changes",1997,"10.1029/97eo00222","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6244263647&doi=10.1029%2f97eo00222&partnerID=40&md5=084a329913276f113329b939acdd1167",[No abstract available]
"7006235542;7004191948;7006377579;57195257572;57193261781;7004239300;7003640784;6603902689;57195355957;7006354036;7102627977;7005198666;7005601996;7004015298;6603393151;7004008268;7004434383;35477504600;6701336868;7102816537;55954833500;7004613032;6602412038;56260361500;7006775179;7102496779;6603577857;56251307100;7003748130;7003566416;7004462114;57214957433;7005287667;7006595513;7005088845;7003377899;57203079636;6507712675;7003405691;7004100461;7004983984;7003708056;7005979765;7007053654;7005140302;7003901333;7404957330;57212913347;7005529361;15919150000;7005174340;24545697300;7006655217;7202968142;6701610867;7203066817;16170561000;36041280100;7006811265;","The Great Dun Fell Cloud Experiment 1993: An overview",1997,"10.1016/S1352-2310(96)00316-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031215137&doi=10.1016%2fS1352-2310%2896%2900316-0&partnerID=40&md5=6ae8eb30b1ac00e4d2cc3ad465b564e4","The 1993 Ground-based Cloud Experiment on Great Dun Fell used a wide range of measurements of trace gases, aerosol particles and cloud droplets at five sites to study their sources and sinks especially those in cloud. These measurements have been interpreted using a variety of models. The conclusions add to our knowledge of air pollution, acidification of the atmosphere and the ground, eutrophication and climate change. The experiment is designed to use the hill cap cloud as a flow-through reactor, and was conducted in varying levels of pollution typical of much of the rural temperate continental northern hemisphere in spring-time."
"7202701936;56472932500;","A study of the ability of pure secondary organic aerosol to act as cloud condensation nuclei",1997,"10.1016/S1352-2310(97)00054-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030616244&doi=10.1016%2fS1352-2310%2897%2900054-X&partnerID=40&md5=470d2f65a8bd6da697648985d5b2718d","Submicron atmospheric particles that serve as cloud condensation nuclei (CCN) at low supersaturations are important for quantifying the effect of aerosols on cloud properties and global climate. In this study, we investigate experimentally the ability of model submicron aerosols consisting of pure organic species to become CCN at typical atmospheric supersaturations. The CCN activity of glutaric acid, adipic acid, and dyoctylphthalate (DOP) aerosols was determined by producing a nearly monodisperse distribution of submicron particles and comparing total CCN concentrations to total number concentrations. The measurements were performed using a Tandem Differential Mobility Analyzer in combination with a cloud condensation nuclei counter at supersaturations of 0.30 and 1.0%. The uncertainty in the measurements was determined by using NaCl and (NH4)2SO4 aerosols; the results indicated that activation diameters could be measured within an error of ± 16%. Adipic acid and glutaric acid aerosols served as CCN at both supersaturations and their behavior is in fair agreement with Kohler theory. On the other hand, DOP aerosol as large as 0.15 μm in diameter, did not become activated, even at supersaturations as high as 1.2%. These results indicate that the CCN activity of hygroscopic organic aerosols may be comparable to that of some inorganic aerosols."
"7003666669;7202048112;55605773361;","Application of cloud microphysics to NCAR community climate model",1997,"10.1029/97jd00703","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031399538&doi=10.1029%2f97jd00703&partnerID=40&md5=91f2b1e8d98e44cbef587f84e0692589","The Colorado State University Regional Atmospheric Modeling System bulk cloud inicrophysics parameterization has been applied to the treatment of stratiform clouds in the National Center for Atmospheric Research community climate model. Predicted cloud properties are mass concentrations of cloud water, cloud ice, rain, and snow and number concentration of ice. Microphysical processes treated include condensation of water vapor and evaporation of cloud water and rain, nucleation of ice crystals, vapor deposition and sublimation of cloud ice and snow, autoconversion and accretion of cloud water, aggregation and collection of cloud ice, melting of ice and snow, riming on ice and snow, and gravitational settling of ice, rain, and snow. Although the parameterization is more detailed and hence more computationally demanding than other cloud microphysics parameterizations in climate models, it treats the Bergeron-Findeisen process explicitly and hence does not require an ad hoc parameterization to distinguish liquid water and ice. A variety of simulations were performed, testing sensitivity to horizontal and vertical resolution, the treatment of ice number, droplet number, and parameterization of cumulus convection. The simulated planetary radiation balance is found to be particularly sensitive to the treatment of ice number and cumulus convection."
"7101677832;","Remote sensing aerosols using satellite infrared observations",1997,"10.1029/96jd03066","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031451339&doi=10.1029%2f96jd03066&partnerID=40&md5=5816c8046d96c5b9fcd07f8da48d1e5a","Aerosol detection techniques using infrared wavelengths have a distinct advantage over visible techniques by providing coverage over bright surfaces and during the night. This study investigates detection of volcanic and soil-derived aerosols, two important aerosols in studies of the earth's climate, using infrared observations at the following approximate wavelengths 8.5, 11, and 12 μm. Detection is based on brightness temperature differences among the three channels BT11-BT12 and BT8-BT11. It is demonstrated that these three infrared channels are useful for detecting stratospheric volcanic aerosols over oceans. Theoretical simulations agree with observations from current satellite instruments. Detection of the stratospheric aerosol over land is complicated by spectral variation of surface emissivity. Retrieving aerosol optical depth over land requires defining the surface spectral emittance. Detecting the presence of soil-derived aerosols can also be aided with infrared observations. Increasing the dust optical depth increases BT11-BT12 and BT8-BT11. The effect is opposite to that of an H2SO4 stratospheric aerosol and differs from an increase in atmospheric precipitable water, though addition of ice clouds moves the differences in the same direction. Retrievals of aerosol optical depth over the desert must account for surface emissivity and the vertical distribution of the dust. Negative differences in BT11-BT12 are observed to occur for dust storms over the Arabian Peninsula, Africa, and the southwest United States and is useful for remote sensing source regions of dust outbreaks. These negative differences can be simulated using the theoretical model but requires a specific dust aerosol model. There are inconsistencies between theoretical simulations of the infrared properties of heavy dust loadings and the satellite observations. Negative differences in BT11-BT12 are useful for detecting and tacking dust storms."
"35464731600;55947099700;7004174939;7004587891;7202887269;7005399437;","Operational remote sensing of tropospheric aerosol over land from EOS moderate resolution imaging spectroradiometer",1997,"10.1029/96jd03988","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031451574&doi=10.1029%2f96jd03988&partnerID=40&md5=723336abba55ed8cbd709f2135888f33","Daily distribution of the aerosol optical thickness and columnar mass concentration will be derived over the continents, from the EOS moderate resolution imaging spectroradiometer (MODIS) using dark land targets. Dark land covers are mainly vegetated areas and dark soils observed in the red and blue channels; therefore the method will be limited to the moist parts of the continents (excluding water and ice cover). After the launch of MODIS the distribution of elevated aerosol concentrations, for example, biomass burning in the tropics or urban industrial aerosol in the midlatitudes, will be continuously monitored. The algorithm takes advantage of the MODIS wide spectral range and high spatial resolution and the strong spectral dependence of the aerosol opacity for most aerosol types that result in low optical thickness in the mid-IR (2.1 and 3.8 μm). The main steps of the algorithm are (1) identification of dark pixels in the mid-IR; (2) estimation of their reflectance at 0.47 and 0.66 μm; and (3) derivation of the optical thickness and mass concentration of the accumulation mode from the detected radiance. To differentiate between dust and aerosol dominated by accumulation mode particles, for example, smoke or sulfates, ratios of the aerosol path radiance at 0.47 and 0.66 μm are used. New dynamic aerosol models for biomass burning aerosol, dust and aerosol from industrial/urban origin, are used to determine the aerosol optical properties used in the algorithm. The error in the retrieved aerosol optical thicknesses, τa, is expected to be Δτa = 0.05 ± 0.2τa. Daily values are stored on a resolution of 10 × 10 pixels (1 km nadir resolution). Weighted and gridded 8-day and monthly composites of the optical thickness, the aerosol mass concentration and spectral radiative forcing are generated for selected scattering angles to increase the accuracy. The daily aerosol information over land and oceans [Tanré et al., this issue], combined with continuous aerosol remote sensing from the ground, will be used to study aerosol climatology, to monitor the sources and sinks of specific aerosol types, and to study the interaction of aerosol with water vapor and clouds and their radiative forcing of climate. The aerosol information will also be used for atmospheric corrections of remotely sensed surface reflectance. In this paper, examples of applications and validations are provided."
"7005227707;7102564690;","Constraints on using AVHRR composite index imagery to study patterns of vegetation cover in boreal forests",1997,"10.1080/014311697217684","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031180205&doi=10.1080%2f014311697217684&partnerID=40&md5=80b1304243d6651127858a9f8cb1f3d1","A wide range of techniques are being developed to map vegetation cover types using multi-date imagery from the Advanced Very High Resolution Radiometer. To date, these techniques do not account for severe constraints which exist for the world's boreal forest. Using composite AVHRR imagery collected over Alaska, we demonstrate how several factors influence the time-series normalized vegetation difference index (NDVI) signatures developed for the boreal forests in this region, including the effects of: (1) clouds and atmospheric haze; (2) climate variations on plant phenology; (3) fire on forest succession; and (4) forest stand patch size with respect to system resolution. Based on the analysis of AVHRR composite data from Alaska, the results of this study show: (1) clouds and haze have distinct effects on the intra-seasonal NDVI signature; (2) there are significant interseasonal variations in NDVI signatures caused by variations in the length of the growing season as well as variations in precipitation and moisture during the growing season; (3) disturbances affect large areas in interior Alaska and forest succession after fire results in significant variations in the inter-seasonal NDVI signatures; and (4) much of the landscape in interior Alaska consists of heterogeneous patches of forest which are much smaller than the resolution cell size of the AVHRR sensor, resulting in significant sub-pixel mixing. Based on these findings, the overall conclusion of this study is scientists using AVHRR to map land cover types in boreal regions must develop approaches which account for these sources of variation. © 1997 Taylor & Francis Group, LLC."
"6602667330;7402717381;7006865796;7004484970;7003371432;","The structure, water budget, and radiational features of a high-latitude warm front",1997,"10.1175/1520-0469(1997)054<1553:TSWBAR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001323415&doi=10.1175%2f1520-0469%281997%29054%3c1553%3aTSWBAR%3e2.0.CO%3b2&partnerID=40&md5=f501a0c4fcc3dc27dd1db2ab6d2915b3","On 30 September 1994 an Arctic low pressure system passed over the southern Beaufort Sea area of northern Canada and research aircraft observations were made within and around the warm front of the storm. This study is unique in that the warm front contained subzero centigrade temperatures across the entire frontal region. The overall structure of the warm front and surrounding region was similar to midlatitude storms; however, the precipitation rates, liquid water content magnitudes, horizontal and vertical winds, vertical wind shear, turbulence, and thermal advection were very weak. In addition, a low-level jet and cloud bands were aligned parallel to the warm front, near-neutral stability occurred within and around the front, and conditional symmetric in stability was likely occurring. A steep frontal region resulted from strong Coriolis influences that in limited the amount of cloud and precipitation ahead of the system. The precipitation efficiency of the storm was high (60%) but is believed to be highly dependent on the stage of development. The mesoscale frontogenetic forcing was primarily controlled by the tilting of isentropic surfaces with confluence/convergence being the secondary influence. Sublimation contributions may have been large in the earlier stages of storm development. Satellite and aircraft radiometers underestimated cloud top heights by as much as 4 km and this was mostly due to the near transparency of the lofted ice layer in the upper portion of the storm. Maximum surface solar radiation deficits ranged between 91 W m-2 and 187 W m-2 at two surface observing sites. This common type of cloud system must have a major impact on the water and energy cycles of northern Canada in the autumn and therefore must be well accounted for within climate models."
"7004591118;","Prolonged leaf senescence in Clusia multiflora H.B.K.",1997,"10.1007/s004680050098","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030905934&doi=10.1007%2fs004680050098&partnerID=40&md5=51c6c728a7f0383d605447c1cc70e6ab","Leaf aging and senescence in Clusia multiflora H.B.K. was investigated by artificial treatments, such as floating leaf discs on water in darkness, or darkening leaves attached to the parent plant in situ in trees living in tropical cloud forest. In both cases several parameters modified by age were evaluated such as nitrogen levels, chlorophyll content, succulence and carbohydrates levels. A prolonged senescence (nearly 3 months in floating leaf discs) was observed, contrasting with species such as Heliocarpus americanus (5 days) and Cecropia palmatisecta (20 days), characterized by low values of leaf weight per area, but similar to species with high leaf weight per area and with high levels of organic acids such as Clusia minor and Fuocroya humboldtiana, where acids may act as a reserve of C and energy. After 30 days in darkness C. multiflora leaf samples collected in the field did not show differences in comparison to non-darkened opposite leaves with respect to chlorophyll, titratable protons and carbohydrates, and leaves performed photosynthesis after 2 months in darkness. The effect of age in leaves was evaluated in a gradient of leaves, sampled at different positions from the apex and ranging in age from 15 days to 2 years old. The study of senescence in tropical wild plants is uncommon, but it is important knowledge for understanding foliar development, and response to internal rather than environmental regulation in climates where seasons are not strongly marked as is the case in the tropical mountain forest, where C. multiflora constitutes an important component in the early successional vegetation."
"57208346904;7501757094;","Cloud overlap effects on general circulation model climate simulations",1997,"10.1029/97jd00630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031427108&doi=10.1029%2f97jd00630&partnerID=40&md5=6621ff8549a0b2b7b47573325a8e5b5c","The vertical distribution of clouds significantly affects the radiative heating/cooling distributions. Consequently, the general circulation model (GCM) simulated climate can be sensitive to the treatment of cloud overlap, which is related to the subgrid scale cloud vertical geometric association. Here we developed and tested a ""mosaic"" treatment that can explicitly consider the cloud association in the GCM radiation parameterization. The effects of this treatment on radiative forcing and climate simulations were studied by comparing the results with those using the ""random"" overlap, which assumes clouds are independent and therefore yields a larger effective cloudiness. The mosaic treatment calculates a significantly different atmospheric radiative heating/cooling distribution caused mainly by the changes in infrared radiation. In the tropics it yields a heating in the upper troposphere and a cooling in the lower troposphere especially near the surface; opposite changes are calculated in the middle to high latitudes. Because of a smaller effective cloudiness the mosaic treatment calculates less infrared downward radiation reaching the surface, which is partially compensated by increased incident solar radiation. Differences in the climate responses are substantial, with several major model biases corrected by the mosaic treatment. For example, the middle to upper troposphere of the tropics and subtropics are warmed by more than 3°C throughout the year, and the polar night northern stratosphere becomes much warmer, up to a maximum of 15°C. A more realistic distribution of tropical precipitation is simulated especially over central to east Pacific oceans. Other notable improvements include the decreased convective rainfall and surface evaporation and the increased atmospheric moisture content. The mosaic treatment also enhances significantly the daily variability of surface air temperature and radiation fluxes in the low latitudes."
"55420585900;7006515850;","Aerosols and climate: Anthropogenic emissions and trends for 50 years",1997,"10.1029/97jd00199","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031407618&doi=10.1029%2f97jd00199&partnerID=40&md5=894c1c5fd0060773753cd0749c943d32","A global inventory has been prepared for anthropogenic particulate emissions into the troposphere that covers the period 1990-2040. The inventory provides estimates for both primary particulate emissions and secondary contributions from atmospheric chemical reactions, particularly of SO2. Using a conventional method, total worldwide anthropogenic emissions of particles &lt;10 μm diameter are estimated at 345 Tg/yr, excluding secondary NO3- and organics. Approximately 35% of the particles entering the troposphere is airborne sulfate from oxidation of SO2 emissions. Emissions worldwide are dominated by fossil fuel combustion, particularly coal, and biomass burning. These emissions are projected to grow by 1.5 2.1 times in 2040, largely from fossil fuel combustion. Growth is expected to be greatest in the developing countries, especially India and China. Present anthropogenic emissions appear to be a small fraction of emissions from natural sources. However, the man-derived component could become comparable to natural emissions by 2040. Increased haziness may enhance negative climate forcing both directly by increased radiative scattering and indirectly by modifying cloud albedo and cover. The forcing will be spatially non-uniform, superimposed on the forcing derived from greenhouse gases."
"7401844779;56270311300;7201966094;","Aerosol climate effects: Local radiative forcing and column closure experiments",1997,"10.1029/97jd00112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031438534&doi=10.1029%2f97jd00112&partnerID=40&md5=ef473415e986a8827b529a596a025fde","In an effort to reduce uncertainties in climate change predictions, experiments are being planned and conducted to measure anthropogenic aerosol properties and effects, including effects on radiative fields. The global average, direct anthropogenic aerosol effect on upwelling shortwave fluxes is estimated to be about +1/2 W m-2, whereas errors in flux changes measured with airborne and spacebome radiometers are 2 to 8 W m-2 or larger. This poses the question of whether flux changes expected in field experiments will be large enough to measure accurately. This paper obtains a new expression for the aerosol-induced change in upwelling flux, compares it to two-stream and adding-doubling (AD) results, and uses all three methods to estimate expected flux changes. The new expression accounts for the solar zenith angle dependences of aerosol transmission and reflection, as well as of surface albedo, all of which can have a strong effect in determining flux changes measured in field experiments. Despite its relative simplicity, the new expression gives results similar to previous two-stream results. Relative to AD results, it agrees within a few watts per square meter for the intermediate solar elevation angles where the flux changes peak (roughly 10° to 30°), but it has negative errors for higher Sun and positive errors for lower Sun. All three techniques yield aerosol-induced changes in upwelling flux of +8 to +50 W m-2 for aerosol midvisible optical depths of 0.1 to 0.5. Because such aerosol optical depths occur frequently off the U.S. and European Atlantic coasts in summer, the flux changes they induce should be measurable by airborne, and possibly by spaceborne, radiometers, provided sufficient care is taken in experiment design (including measurements to separate aerosol radiative effects from those of absorbing gases). The expected flux changes are about 15 to 100 times larger than the global average flux change expected for the global average anthropogenic sulfate optical depth of 0.04. Reasons for the larger flux changes include the larger optical depths considered here (factor 2.5 to 12), plus restricting the measurements to cloud-free, daytime conditions over the ocean (factor 5 to 9)."
"7402755025;7408612236;","Variability of radiative cooling during the Asian summer monsoon and its influence on intraseasonal waves",1997,"10.1175/1520-0469(1997)054<0941:VORCDT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031444329&doi=10.1175%2f1520-0469%281997%29054%3c0941%3aVORCDT%3e2.0.CO%3b2&partnerID=40&md5=cf355f9b18656ac4d39432b7405a5496","Infrared radiative cooling rates are calculated over the Asian summer monsoon between 5°S-20°N and 40°-135°E at a spatial resolution of 5° × 5° for the summer seasons of 1984 and 1987. A medium spectral resolution infrared radiative transfer model with specified temperature, moisture, clouds, and trace gas distributions is used to obtain the cooling rate profiles. Cloud distributions for the two summers are obtained from Indian National Satellite measurements. Seasonal mean and intraseasonal variations of clouds and radiative cooling rates over a 21-76-day range of periods are examined. The analysis identifies centers over the central and eastern Indian Ocean, and western Pacific Ocean, along the equator, and along 15°N, where seasonal mean cloud amounts range from 40% to 80% with cloud tops mostly in the middle and upper troposphere. Intraseasonal variability of clouds is also large over these centers (% variances &gt;25%). Consistently, seasonal mean cooling rates are at a maximum (3°-5°C day-1) in the upper troposphere between 300 and 400 mb, related to cloud-top cooling. The cooling rates below 400 mb are between 1° and 3°C day-1. The cooling rates exhibit intraseasonal amplitudes of 1.0°-1.50C day-1. The largest amplitudes are found between 300 and 500 mb, indicating that cooling rate variability is directly related to intraseasonal variability of convective clouds. Spatial distributions of clouds and cooling rates remain similar during the 1984 and 1987 summer seasons. However, during 1987, intraseasonal amplitudes of deep convective cloud amount and cooling rate over the Indian Ocean are 10%-15% larger than in 1984. It is shown that intraseasonal variability of cooling rates over the Indian Ocean can perturb convective heating by 10%-30% in the upper and lower troposphere. Based on a one-dimensional radiative-convective equilibrium model, it is estimated that the radiative damping timescale over the Indian Ocean region is ∼3 days. Based on this damping timescale and in conjunction with a model of equatorial Kelvin waves with first baroclinic mode, it is hypothesized that the variable cloud-radiative cooling rates can alter phase speeds of Kelvin waves by up to 60%. This helps explain why the frequency range of intraseasonal oscillations is so broad."
"7003640407;56033135100;","Geological evaluation of climate General Circulation Models and model implications for Mesozoic cloud cover",1997,"10.1111/j.1365-3121.1997.tb00006.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031469872&doi=10.1111%2fj.1365-3121.1997.tb00006.x&partnerID=40&md5=cdd6f9a92893998de6a089122a2caff5","General Circulation Models (GCMs) are currently used to predict future global change. However, the robustness of GCMs can, and should, be evaluated by their ability to simulate past climate regimes. Their success in 'retrodiction' can then be assessed by reference to the testimony of the geological record. Geological evidence provides a database which can be used in the estimation of sea surface temperatures and other proxy data useful in palaeoclimatic studies. These data can then be used to refine the prescribed boundary conditions for running GCMs themselves. Results of modelling experiments confirm a generally warmer Mesozoic earth with arid tropics and convective rainfall higher over the oceans than at present. Circum-polar wetlands are also indicated. Modelled cloudiness is also higher in the Mesozoic, contributing to greenhouse conditions and possibly influencing terrestrial biomes and marine ecosystems."
"6602267357;7006729638;","Sensitivity of vegetation (ndvi) to climate over southern africa: Relationships with summer rainfall and olr",1997,"10.1080/03736245.1997.9713622","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031460334&doi=10.1080%2f03736245.1997.9713622&partnerID=40&md5=230491426ce604d1baae21f9e2e240e4","Relationships between satellite normalised difference vegetation index (NDVI) and outgoing longwave radiation (OLR) data are studied over southern Africa. Analysis of the seasonal cycle confirms an inverse relationship, whereby reduced OLR in summer resulting from increased clouds and rainfall contributes to an increase in the vegetative density and cover. Field-to-field correlations between OLR and NDVI in the period 1982–1993 are significantly negative in late summer (January-April) in a N-S axis south of 20°S. The weather Regimes of early summer, made up of continental troughs, appear less able to influence vegetation than those in the late summer dominated by an anticyclone to the east. Positive (inverted) correlations between OLR and NDVI occur in the 10–15°S ITCZ Region where annual rainfall is > 1 m. Interannual variability of OLR and NDVI are associated with the El Nino Southern Oscillation (ENSO) cycle, driven by warming of the tropical Atlantic and Indian Oceans. Principal components analysis identifies a large area of sympathetic response over the central plateau of southern Africa in OLR, and NDVI. a gridded summer rainfall time series from 1905 exhibits a nearly identical spatial loading pattern, and gives added meaning to satellite results in the 1982–1993 period. © 1997 Taylor & Francis Group, LLC."
"7006246996;7402780356;","Measurement of surface radiation fluxes and cloud optical properties during the 1994 Arctic Ocean Section",1997,"10.1029/96jd03215","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030792320&doi=10.1029%2f96jd03215&partnerID=40&md5=74b8aef700406febe11255a9ad55c996","During a voyage to the north pole from Alaska by the icebreakers USCGC Polar Sea and Canadian CGC Louis S. St.-Laurent (the 1994 Arctic Ocean Section, July 24 to September 3) an atmospheric radiation and remote sensing experiment measured downwelling shortwave and longwave radiation reaching the sea ice surface. The experiment included a Fourier transform infrared (FTIR) spectroradiometer which measured zenith radiance at 1 cm-1 resolution in the middle infrared wavelength range 5-20 μm, an Eppley pyranometer measuring most of the downwelling shortwave flux (0.28-2.80 μm), an Eppley pyranometer measuring the downwelling near-infrared flux (0.78-2.80 μm) an Eppley pyrgeometer measuring the downwelling longwave flux. In conjunction with a discrete-ordinates radiative transfer model, the FTIR emission spectra are used to estimate 8-12 μm cloud emissivity and effective radius of the cloud droplet size distribution. The broadband shortwave flux measurements are used to estimate shortwave cloud scattering optical depth. Most of the FTIR emission spectra recorded under overcast skies are consistent with cloud effective radius in the range 10-12 μm, but 27% of the spectra are more consistent with the range 4-6 μm, suggesting an occasional continental aerosol influence to Arctic cloud microphysics. The average daily shortwave cloud-scattering optical depth ranged from 2 to 46, which is similar to a range inferred from radiometer data recorded at Barrow, Alaska, during the same season. The downwelling shortwave flux measurements and estimates of net surface flux are generally consistent with a four-decade Russian climatology but also suggest that the frequency of cloud cover sampled during the 1994 Arctic Ocean Section was somewhat larger than the climatological average. These radiation measurement data from the 1994 Arctic Ocean Section should be useful for examining the treatment of atmospheric radiation and surface energy input in Arctic climate model simulations."
"7201496259;7102604282;57210518852;7202301082;7401785020;","An assessment of the radiative effects of anthropogenic sulfate",1997,"10.1029/96jd03087","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0012795448&doi=10.1029%2f96jd03087&partnerID=40&md5=7a8820db8da411707abecf51d62b2f0f","We use a coupled climate/chemistry model with cloud nucleation processes parameterized in terms of local aerosol number, anthropogenic sulfate mass concentration, and updraft velocity to investigate both direct and indirect anthropogenic sulfate radiative forcings. We estimate that the global direct radiative forcing is about -0.4 W m-2 with a maximum over Europe where the strongest anthropogenic sulfur emissions occur. With different approaches for the formation of anthropogenic sulfate and its relation to aerosol size distribution, we estimate that the indirect forcing may range from -0.6 to -1.6 W m-2. This range reduces to -0.4 to -1.1 W m-2 if a prescribed marine background particle number concentration is universally applied over the ocean. Contrary to the direct effect which is more significant over continents, the calculated maximum of indirect forcing is located over the Atlantic Ocean near the coastline of North America. Our simulations indicate that anthropogenic sulfate may result in important increases in reflected solar radiation, which would mask locally the warming from increased greenhouse gases. We also compare the simulated cloud drop effective radii with those retrieved from satellite data to validate the accuracy of our cloud drop parameterization."
"7202569095;","The role of diatoms, dissolved silicate and antarctic glaciation in glacial/interglacial climatic change: A hypothesis",1997,"10.1016/S0921-8181(96)00005-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031060871&doi=10.1016%2fS0921-8181%2896%2900005-7&partnerID=40&md5=552f1c6e4b34129f62cadb8c5eff45aa","A new theory is proposed to explain global cooling at the onset of Pleistocene glacial periods. Atmospheric CO2 drawdown is considered to be the driving force behind global cooling, brought about by heightened productivity at the equatorial divergences and along continental margins, particularly in upwelling regions. Eutrophication appears to be triggered when global warming during late interglacial periods causes accelerated melting of the West Antarctic Ice Sheet. This would release large reserves of silicate-enriched subglacial meltwaters into the surrounding oceans where entertainment would take place into deep and intermediate currents forming in Antarctic and subantarctic waters. Subsequent advection, mixing and upwelling of silicate-enriched deep and intermediate waters into the coastal zones and open-ocean divergences results in the proliferation of large, rapidly-sinking diatom species with a high affinity for dissolved silicate. These blooms enhance rates of recycling of N and P in upwelling regions and accelerate rates of organic carbon production, export and sequestration in shelf and slope sediments and in the deep sea. The resultant arm. CO2 drawdown initiates global cooling. Consequent expansion of Northern Hemisphere glaciers lowers sea level, while increased temperature and pressure gradients between equatorial and polar regions intensify meridional winds. The former process exposes nutrient-enriched coastal sediments to wave erosion, thereby releasing new nutrient supplies, while the latter process enhances upwelling. The combined effect is to greatly increase rates of org. C production and export from continental margins and further accelerate arm. CO2 drawdown. Glacial-period cooling is also enhanced by a number of other positive feedbacks, including changes in albedo, water vapour and cloud cover. Episodic warming intervals during glacial periods may be related to insolation changes associated with orbital precession and tilt cycles, but processes involved in deglaciation and reversion to the interglacial climatic regime are complex and not yet fully understood."
"55714712500;57196499374;","Effect of clouds on direct aerosol radiative forcing of climate",1997,"10.1016/S0021-8502(97)85212-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0039380160&doi=10.1016%2fS0021-8502%2897%2985212-3&partnerID=40&md5=3b9f86cd28b7e9b16aa09179e4e86e87",[No abstract available]
"6603353298;7003644931;","An assessment of climatological cloud characteristics in South Eastern mediterranean in support of the study of the interaction between climate and life processes",1997,"10.1080/02772249709358430","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030894533&doi=10.1080%2f02772249709358430&partnerID=40&md5=f5765886969555c35fdcee38500b5f26","Seasonal means of the spatial and temporal distribution of cloud cover and cloud water path in the South Eastern Mediterranean area are calculated in an effort to support the study of the interactions between climate and life processes. The seasonal amplitude of cloud cover reaches its maximum value in 1988 and its minimum value in 1989 whereas the seasonal amplitude of cloud water path reaches its maximum value in 1985. Zonally averaged values of cloud cover increase with latitude in summer, whereas in winter a maximum at 36, 25° is observed. In terms of cloud water path, its zonal values increase with latitude in both winter and summer. Results, in general, agree well with previous cloud climatologies."
"56165006900;6603568514;7102577095;","Cloud radiation forcings and feedbacks: General circulation model tests and observational validation",1997,"10.1175/1520-0442(1997)010<2479:CRFAFG>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031410809&doi=10.1175%2f1520-0442%281997%29010%3c2479%3aCRFAFG%3e2.0.CO%3b2&partnerID=40&md5=4bbf81a7555a2edc618ac15ea98020ee","Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different cloud radiation parameterizations have been investigated. In addition to the original cloud radiation scheme of CCM2, four parameterizations incorporating prognostic cloud water were tested: one version with prescribed cloud radiative properties and three other versions with interactive cloud radiative properties. The authors' numerical experiments employ perpetual July integrations driven by globally constant sea surface temperature forcings of two degrees, both positive and negative. A diagnostic radiation calculation has been applied to investigate the partial contributions of high, middle, and low cloud to the total cloud radiative forcing, as well as the contributions of water vapor temperature and cloud to the net climate feedback. The high cloud net radiative forcing is positive, and the middle and low cloud net radiative forcings are negative. The total net cloud forcing is negative in all of the model versions. The effect of interactive cloud radiative properties on global climate sensitivity is significant. The net cloud radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and the schemes with specified properties. The increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount simply produces a positive shortwave feedback for the schemes with a specified cloud water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. These cloud radiation parameterization are empirically validated by using a single-column diagnostic model, together with measurements from the Atmospheric Radiation Measurement program and from the Tropical Ocean Global Atmosphere Combined Ocean-Atmosphere Response Experiment. The inclusion of prognostic cloud water produces a notable improvement in the realism of the parameterization, as judged by these observations. Furthermore, the observational evidence suggests that deriving cloud radiative properties from cloud water content and microphysical characteristics is a promising route to further improvement."
"7403906746;","Climate change and the global atmospheric electrical system",1997,"10.1016/S1352-2310(97)00108-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031259795&doi=10.1016%2fS1352-2310%2897%2900108-8&partnerID=40&md5=9bafddf945ad907a5822d57528604a40","In a tropical region, an increase in lightning can be expected to be associated with an increase in temperature and this could be a non-linear effect. This might have consequences for global ozone and probably to a lesser extent, carbon dioxide. Whether the change in ion flux can contribute further significant positive climate feedbacks via clouds and aerosol depends on unravelling the many remaining uncertainties of electrical cloud microphysics. The curious electrical coupling between lower and upper atmosphere, however, seems likely to increase."
"7006712143;6603086928;35461255500;7202488998;","Supercooled cirrus cloud formation modified by nitric acid pollution of the upper troposphere",1997,"10.1029/97GL02996","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031381564&doi=10.1029%2f97GL02996&partnerID=40&md5=6630f0fc0bfcb891dddf5dae90bf4668","We have investigated nitric acid induced cirrus cloud formation in the upper troposphere. Our theoretical model investigations were made in the light of recent upper tropospheric gaseous nitric acid observations which show higher than expected nitric acid abundances. Our investigations indicate markedly increased cloud condensation nuclei number densities due to nitric acid induced aerosol activation. Our findings suggest that nitric acid may substantially modify supercooled cirrus cloud formation at temperatures above -40°C and thereby influence climate. Copyright 1997 by the American Geophysical Union."
"6602729528;","Recent changes in solar radiation under cloudy conditions in Germany",1997,"10.1002/(sici)1097-0088(19971130)17:14<1581::aid-joc214>3.0.co;2-h","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031394338&doi=10.1002%2f%28sici%291097-0088%2819971130%2917%3a14%3c1581%3a%3aaid-joc214%3e3.0.co%3b2-h&partnerID=40&md5=ecc8807aad3183da85c6b93038eca184","Hourly data of global and diffuse solar radiation in combination with cloud type, cloud cover amount and sunshine duration records are analysed for two in Germany. The global solar radiation for overcast conditions at urban, maritime influenced Hamaburg and at the rural mountain station Hobenpeissenberg decreased by an average rate of 8 per cent decade between 1964 and 1990, whereas no significant trend was found under clear skies at either station. However, under partly cloudy conditions the diffuse portion of global solar radiation also declined. Although the total cloud cover amount changed little during the interval analysed, the frequency of cirrus cloud in Hamburg and Hobenpeissenberg by 12 per cent and 14 per cent respectively. This may have led to the decline of diffuse solar radiation in cloudy conditions. A shift from stratiform to more frequent convective clouds also occurred at both stations. At Hamburg and Hohenpeissenberg the mean direct solar radiation income was 10 W m-1 higher during hours with 100 per cent sunshine duration and observed clouds than during hours with totally clear skies. Possible reasons for the observed cloud changes include natural weather variability of convective and atratiform clouds, increase of aircraft traffic increasing the occurrence of cirrus clouds and an indirect aerosol effect on the maritime stratiform clouds. © 1997 Royal Meteorological Society."
"6602940714;57201527575;","Variation of cosmic ray flux and global cloud coverage - A missing link in solar-climate relationships",1997,"10.1016/S1364-6826(97)00001-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031431792&doi=10.1016%2fS1364-6826%2897%2900001-1&partnerID=40&md5=37f620735a4be6f451457dfc7e46b08f","In the search for a physical mechanism that could account for reported correlations between solar activity parameters and climate, we have investigated the global cloud cover observed by satellites. We find that the observed variation of 3-4% of the global cloud cover during the recent solar cycle is strongly correlated with the cosmic ray flux. This, in turn, is inversely correlated with the solar activity. The effect is larger at higher latitudes in agreement with the shielding effect of the Earth's magnetic field on high-energy charged particles. The observed systematic variation in cloud cover will have a significant effect on the incoming solar radiation and may, therefore, provide a possible explanation of the tropospheric and stratospheric 10-12 year oscillations which have been reported. The above relation between cosmic ray flux and cloud cover should also be of importance in an explanation of the correlation between solar cycle length and global temperature, that has been found. © 1997 Elsevier Science Ltd."
"36705143500;","Tropical thermostats and low cloud cover",1997,"10.1175/1520-0442(1997)010<0409:TTALCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031445221&doi=10.1175%2f1520-0442%281997%29010%3c0409%3aTTALCC%3e2.0.CO%3b2&partnerID=40&md5=406c597a380776f73060ddb7ebce333b","The ability of subtropical stratus low cloud cover to moderate or amplify the tropical response to climate forcing such as increased CO2 is considered. Cloud radiative forcing over the subtropics is parameterized using an empirical relation between stratus cloud cover and the difference in potential temperature between 700 mb (a level that is above the trade inversion) and the surface. This relation includes the empirical negative correlation between SST and low cloud cover and is potentially a positive feedback to climate forcing. Since potential temperature above the trade inversion varies in unison across the Tropics as a result of the large-scale circulation and because moist convection relates tropospheric temperature within the convecting region to variations in surface temperature and moisture, the subtropical potential temperature at 700 mb depends upon surface conditions within the convecting region. As a result, subtropical stratus cloud cover and the associated feedback depend upon the entire tropical climate and not just the underlying SST. A simple tropical model is constructed, consisting of separate budgets of dry static energy and moisture for the convecting region (referred to as the ""warm"" pool) and the subtropical descending region (the ""cold"" pool). The cold pool is the location of stratus low clouds in the model. Dynamics is implicitly included through the assumption that temperature above the boundary layer is horizontally uniform as a result of the large-scale circulation. The tropopause and warm pool surface are shown to be connected by a moist adiabat in the limit of vanishingly narrow convective updrafts. Stratus low cloud cover is found to be a negative feedback, increasing in response to doubled CO2 and reducing the tropically averaged warming in comparison to the warming with low cloud cover held fixed. Increased low cloud cover is shown to result from the increased difference in surface temperature between the warm and cold pools, and the increased low-level static stability over the warm pool, equal to the increase in potential temperature along the moist adiabat originating in the warm pool mixed layer."
"6508079704;6603942055;7004411888;","Sensitivity of a GCM to changes in the droplet effective radius parameterization",1997,"10.1029/97GL00214","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031071770&doi=10.1029%2f97GL00214&partnerID=40&md5=64f2fb68fdc3048174a6cb62b23f6270","The French Community Climate model (ARPEGE-climat) has been used in relation to four different warm cloud droplet effective radius parameterizations in order to simulate the January and July climatologies. Two of these parameterizations depend upon the cloud character (maritime or continental). The comparison between the results of the different simulations reveals that the model is very sensitive to the effective radius parameterization change. This change induces differences up to 30Wm-2 in the global values of the radiative fluxes at the top of the atmosphere and at the surface level. Important differences are also induced in the zonally averaged short-wave cloud radiative forcing, cloudiness and precipitation. At smaller scales, non negligible precipitation and surface temperature changes are also observed. The comparison between the simulation results obtained by using model versions containing the above parameterizations reveals that two of them considerably improve the agreement between model and climatological cloudiness, thus allowing a pertinent choice of the most appropriate cloud droplet effective radius parameterization."
"57201527575;6602940714;","What do we really know about the sun-climate connection?",1997,"10.1016/S0273-1177(97)00499-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0040932669&doi=10.1016%2fS0273-1177%2897%2900499-7&partnerID=40&md5=ada454b4aee0d243bf069ba2edde2462","The Earth's climate has always been changing. This is documented in historical as well as in geological records. The reasons for these changes, however, have always been subject to discussions and are still not well understood. In addition to natural climate changes the risk of human influence on climate has recently been seriously considered by the Intergovernmental Panel on Climate Change. Any factor that alters the radiation received from the Sun or lost to Space will affect climate. The Sun's output of energy is known to change over an 11-year cycle, and variations over longer periods occur as well. A number of correlations between solar activity variations and climate changes, some more significant than others, have been reported but they have traditionally been accompanied by a considerable skepticism among scientists because a plausible physical mechanism to account for these correlations has not yet been found. The most immediate cause of climate changes would be changes in the total irradiance of the Sun. This, however, would either imply unrealistically large variations in total solar irradiance or a higher climate sensitivity to radiative forcing than normally accepted. Therefore other mechanisms have to be invoked. The most promising candidate is a change in cloud formation because clouds have a very strong impact on the radiation balance and because only little energy is needed to change the cloud formation process. One of the ways to influence cloud formation might be through the cosmic ray flux that is strongly modulated by the varying solar activity. ©1997 COSPAR. Published by Elsevier Science Ltd."
"7003960899;","Climatic variability of cloud radiative forcing",1997,"10.1256/smsqj.54012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031443698&doi=10.1256%2fsmsqj.54012&partnerID=40&md5=4dcac5d50f2a1713b4f51d38b620aab1","Multiple-regression models have been developed relating interannual departures of the Earth Radiation Budget Satellite net, long-wave, and short-wave cloud radiative forcing primarily to variations in the International Satellite Cloud Climatology Project cloud amounts for low, middle and high clouds, and cloud water. These models are used to evaluate the effects on cloud radiative forcing of specified and observed changes in cloud properties. The calculated changes of cloud forcing due to 16.5% increases in low-, middle- and high-cloud amounts and 25% increases in cloud water are compared with those of a radiative-transfer model. The two methods have results which agree with respect to the signs of the responses and the order of the significance of the independent variables for net cloud forcing. Overall, variations in cloud water have the largest effect on net cloud forcing; those in high cloud have the largest effect on long-wave cloud forcing; those in cloud water make the largest contributions to short-wave cloud forcing. Using the statistical models forced by one-standard-deviation variations in cloud properties, variations in high cloud are shown to have increased importance relative to the results for the 16.5 and 25% perturbations. in addition, variations in clear-sky planetary albedo and long-wave flux are also found to be important at higher latitudes. In a small sample of observed short-term climate-change scenarios, compensations amongst the effects of the variables alter the magnitude, and in two cases the sign, of the change in net cloud forcing relative to those resulting from uniform variations of the cloud properties."
"57212781009;7101785401;6701715507;","Non-linear climate feedback analysis in an atmospheric general circulation model",1997,"10.1007/s003820050193","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031402661&doi=10.1007%2fs003820050193&partnerID=40&md5=1d5b81521c2e2b3f078bee374a6d747b","A method is described for evaluating the 'partial derivatives' of globally averaged top-of-atmosphere (TOA) radiation changes with respect to basic climate model physical parameters. This method is used to analyse feedbacks in the Australian Bureau of Meteorology Research Centre general circulation model. The parameters considered are surface temperature, water vapour, lapse rate and cloud cover. The climate forcing which produces the changes is a globally uniform sea surface temperature (SST) perturbation. The first and second order differentials of model parameters with respect to the forcing (i.e. SST changes) are estimated from quadratic least square fitting. Except for total cloud cover, variables are found to be strong functions of global SST. Strongly non-linear variations of lapse rate and high cloud amount and height appear to relate to the non-linear response in penetrative convection. Globally averaged TOA radiation differentials with respect to model parameters are also evaluated. With the exception of total cloud contributions, a high correlation is generally found to exist, on the global mean level, between TOA radiation and the respective parameter perturbations. The largest non-linear terms contributing to radiative changes are those due to lapse rate and high cloud. The contributions of linear and non-linear terms to the overall radiative response from a 4 K SST perturbation are assessed. Significant non-linear responses are found to be associated with lapse rate, water vapour and cloud changes. Although the exact magnitude of these responses is likely to be a function of the particular model as well as the imposed SST perturbation pattern, the present experiments flag these as processes which cannot properly be understood from linear theory in the evaluation of climate change sensitivity."
"7202923875;7406514318;","Radiative forcing and response of a GCM to ice age boundary conditions: Cloud feedback and climate sensitivity",1997,"10.1007/s003820050199","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031408639&doi=10.1007%2fs003820050199&partnerID=40&md5=4d8ea2e16b234ce61a37379f9caba128","A general circulation model is used to examine the effects of reduced atmospheric CO2, insolation changes and an updated reconstruction of the continental ice sheets at the Last Glacial Maximum (LGM). A set of experiments is performed to estimate the radiative forcing from each of the boundary conditions. These calculations are used to estimate a total radiative forcing for the climate of the LGM. The response of the general circulation model to the forcing from each of the changed boundary conditions is then investigated. About two-thirds of the simulated glacial cooling is due to the presence of the continental ice sheets. The effect of the cloud feedback is substantially modified where there are large changes to surface albedo. Finally, the climate sensitivity is estimated based on the global mean LGM radiative forcing and temperature response, and is compared to the climate sensitivity calculated from equilibrium experiments with atmospheric CO2 doubled from present day concentration. The calculations here using the model and palaeodata support a climate sensitivity of about 1 Wm-2K-1 which is within the conventional range."
"7101679850;8703963700;7404260195;7403324157;","Acid rain and below-cloud scavenging in South-Western China",1997,"10.1023/A:1005852700933","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030707914&doi=10.1023%2fA%3a1005852700933&partnerID=40&md5=405f9f014848353da761f61bd040327e","Major urban areas in south-western China exhibit unique air pollution problems due to increasing use of high sulphur-content fuels in an environment of unfavourable topography and climate. Ambient levels of sulphur dioxide exceed the air quality objectives, and this gas is the major precursor of acid rain. Cloudwater chemistry studies are reported for urban, suburban and countryside locations, during the period 1985-1989. Although cloudwater acidity was found to increase towards the cloud base, the acidity was much greater for rainwater samples collected simultaneously, and was more pronounced in urban rather than neighbouring suburban or countryside regions. The main contribution to the acidity arises from below-cloud scavenging of gas and aerosol and model calculations are able to simulate this behaviour."
"6603809220;","A physically based scheme for the treatment of stratiform clouds and precipitation in large-scale models. I: Description and evaluation of the microphysical processes",1997,"10.1002/qj.49712354106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031416166&doi=10.1002%2fqj.49712354106&partnerID=40&md5=87fb0833e9dc1121307bedad9544d66d","A stratiform-cloud and precipitation scheme, incorporating prognostic variables for cloud liquid water and cloud ice, has been developed for the CSIRO global climate model (GCM). The scheme includes physically based treatments of key microphysical processes, turbulent mixing and semi-Lagrangian advection of cloud-water species and interactive cloud radiative properties. Objectives in the development of the scheme were to improve upon the physical realism of parametrizations used in earlier schemes, whilst also trying to provide a scheme with moderate computational overheads. The parametrized microphysical processes are evaluated in relation to observations and theory, and are compared to treatments used in earlier schemes in a series of short GCM experiments. It is argued that the treatment of precipitation formation in warm, and mixed-phase, stratiform clouds is more realistic in the present scheme than in earlier schemes, which used crude methods for the parametrization of autoconversion, and did not treat key ice-processes in a consistent way. In the present scheme, accretion processes are more important, whereas autoconversion is less important than in earlier schemes. To determine whether the cloud scheme requires the use of a reduced (split) time-step, the sensitivity of the various terms to the time-step is evaluated in another series of short GCM experiments. It is shown that the various terms are not very sensitive to the time-step, so the scheme can be efficiently implemented without the use of a split time-step. Overall, analytical or time-centred treatments perform better than implicit or explicit schemes, especially in the calculation of the precipitation of cloud ice, where only an accurate analytical treatment is found to perform satisfactorily at large time-steps. As a preliminary validation of the scheme, zonal-mean fields from a six-year model-run are presented for the month of July. The results generally agree well with observations; in particular, the modelled cloudiness and long-wave cloud-forcing fields are more realistic than those obtained with the standard version of the CSIRO GCM."
"7201472576;","Cloud climate investigations in the Nordic region using NOAA AVHRR data",1997,"10.1007/BF00863612","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031431636&doi=10.1007%2fBF00863612&partnerID=40&md5=e9cc3a3760df95e095524769bc35e86c","A method to estimate monthly cloud conditions (monthly cloud frequencies) from multispectral satellite imagery is described. The operational cloud classification scheme SCANDIA (the SMHI Cloud ANalysis model using Digital AVHRR data), based on high resolution imagery from the polar orbiting NOAA-satellites, has been used to produce monthly cloud frequencies for the entire year of 1993 and some additional months in 1991, 1992, 1994 and 1995. Cloud analyses were made for an area covering the Nordic countries with a horizontal resolution of four km. Examples of seasonal, monthly and diurnal variation in cloud conditions are given and an annual mean for 1993 is presented. Comparisons with existing surface observations showed very good agreement for horizontal cloud distributions but approximately 5% smaller cloud amounts were found in the satellite estimations. The most evident problems were encountered in the winter season due to difficulties in identifying low-level cloudiness at very low sun elevations. The underestimation in the summer season was partly fictious and caused by the overestimation of convective cloud cover by surface observers. SCANDIA results were compared to ISCCP (International Satellite Cloud Climatology Project) cloud climatologies for two selected months in 1991 and 1992. ISCCP cloudiness was indicated to be higher, especially during the month with anticyclonic conditions where a cloudiness excess of more than 10% were found. The regional variation of cloud conditions in the area was found to be inadequately described by ISCCP cloud climatologies. An improvement of the horizontal resolution of ISCCP data seems necessary to enable use for regional applications. SCANDIA model is proposed as a valuable tool for local and regional monitoring of the cloud climatology at high latitudes. More extensive comparisons with ISCCP cloud climatologies are suggested as well as comparisons with modelled cloudiness from atmospheric general circulation models and climate models. Special studies of cloud conditions in the Polar areas are also proposed."
"7005966519;","Late Quaternary vegetation, climate and fire history from the tropical mountain region of Morro de Itapeva, SE Brazil",1997,"10.1016/S0031-0182(97)88177-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030620104&doi=10.1016%2fS0031-0182%2897%2988177-1&partnerID=40&md5=8e0683b0e28c64d4f2d13326fc21502c","Late Quaternary paleoenvironments have been interpreted from a 35,000 yr B.P. pollen and charcoal record from Morro de Itapeva (22''47'S, 45''32'W, 1850 m a.s.l.) in the SE Brazilian highlands. Changes in taxa composition and elevational shifts in high elevation grassland (campos de altitude), Araucaria forest, cloud forest and Atlantic rain forest, all of which can be found in the study area today, indicate climatic changes in the past. Expanded high elevation grasslands, absence of Araucaria forest, cloud forest and Atlantic rain forest during the recorded last glacial period (ca. 35,000-17,000 yr B.P.) suggest a climate markedly cooler and drier than today. Development of a Sphagnum peat bog, rare presence of Araucaria forest taxa and existence of a narrow cloud forest and rain forest belt at lower elevations during the late glacial period (17,000-ca. 10,000 yr B.P.) indicate a change to a cool and somewhat moister climates. During the early Holocene cloud forest developed close to the study site, reflecting a warm and moist climate on the east facing slopes, but a drier climate on the highland plateau, evidenced by the rare presence of Araucaria and Podocarpus. Only during the late Holocene moisture increases in the highlands, suggested by the higher frequency of Araucaria and Podocarpus. Fires were more frequent daring the last glacial than during the Holocene."
"56066847900;","Correlation of cloud radiative forcing with clear-sky flux: Seasonal variations of longwave components",1997,"10.1002/(SICI)1097-0088(199710)17:12<1369::AID-JOC199>3.0.CO;2-U","https://www.scopus.com/inward/record.uri?eid=2-s2.0-8744304743&doi=10.1002%2f%28SICI%291097-0088%28199710%2917%3a12%3c1369%3a%3aAID-JOC199%3e3.0.CO%3b2-U&partnerID=40&md5=e3fac343aa6fdebff00578bd6da14e1f","Variations of cloud radiative forcing (CRF) have been considered important in the analysis of cloud-climate interactions. As CRF ts defined to be the difference between clear-sky and total fluxes, of some concern is the contribution of clear-sky flux variations to the observed CRF variations This study investigates the relationship between longwave (LW) CRF and clear-sky LW flux (LW CS) variations using the tarth Radiation Budget Experiment (ERBE) monthly mean data for the period February 1985 through to January 1989 It is illustrated that positive correlations, which are especially strong in the Northern Hemisphere mid- lo high-latitude continents, are found in the extratroptcs, whereas strong negative correlations dominate in the tropics. These latitudinal characteristics of correlations are shown to be linked to the strength of seasonal changes of LW CS relative to the LW CRF counterpart Further analysts demonstrates that the seasonal changes of LW CRF in the tropics are significantly correlated with the corresponding changes of clouds, and those in the mid- to high latitudes are substantially influenced by the corresponding changes of surface and atmospheric temperatures. © 1997 by the Royal Meteorological Society."
"7004993886;7005634455;6603031108;","Evaluating moist physics for Antarctic mesoscale simulations",1997,"10.1017/s0260305500014166","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031403178&doi=10.1017%2fs0260305500014166&partnerID=40&md5=7404a4e6e4fa3e245bd664f85186ed76","The performance of an explicit cloud physics parameterization is examined with simulations of high southern latitude winter climate using a version of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model, version 4. The results reveal that there are three moist physics regimes in the vertical over the elevated interior of Antarctica: the very cold upper troposphere, and relatively warm middle troposphere and the cold boundary layer. Deficiencies for these layers include excessive cloud ice in the upper troposphere, excessive cloud ice in the inversion layer near the ice surface, overly warm temperatures in the lower troposphere, overly cold temperatures in the upper troposphere and excessive downward longwave radiation at the Earth's surface. Three sensitivity experiments were performed to investigate possible improvements in the cloud parameterization. The results indicate that a reduction of the numerous cloud condensation nuclei, while reducing some errors, appears to be insufficient to improve the simulation. A reduction in the excessive cloud ice in the upper troposphere significantly improves the simulation of upper-tropospheric temperature."
"7006729638;","Inter-annual climate modes over southern Africa from satellite cloud OLR 1975-1994",1997,"10.1007/BF00863610","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031408428&doi=10.1007%2fBF00863610&partnerID=40&md5=27a1b392fc4b6d7bc1eecdc042e7592e","Principal components analysis of satellite outgoing longwave radiation (OLR) anomalies over southern Africa forms the basis of this work. OLR anomalies, which are closely correlated with rainfall anomalies and vegetation cover, are formulated for early and late summer, the season when convective clouds develop over southern Africa. The first four principal component modes account for 82 to 85% of the total inter-annual convective variability in the period 1975-1994. The dominant terrestrial modes take the form of truncated dipoles (36%). NW-SE oriented loading patterns contributed by cloud bands and poleward tropical outflows, form the second most important climate mode (25%). Lower order modes are dominated by monsoon effects (12%) and isolated cells (10%). The dominant modes of convective variability appear related to the phase of the Southern Oscillation and its regional signals. The principal component results indicate that attention should be given to understanding mechanisms underlying dipole circulation systems."
"7202048299;7004014731;","The role of cloud diurnal variations in the time-mean energy budget",1997,"10.1175/1520-0442(1997)010<1114:TROCDV>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031428857&doi=10.1175%2f1520-0442%281997%29010%3c1114%3aTROCDV%3e2.0.CO%3b2&partnerID=40&md5=dcf1d2f1079521efee05fd8835529783","The contribution to time-mean energetics from cloud diurnal variations is investigated. Cloud diurnal contributions to radiative fluxes follow as the differences between time-mean radiative fluxes based on diurnally varying cloud properties and those based on fixed cloud properties. Time-mean energetics under both conditions are derived from an observationally driven radiative transfer calculation in which cloud cover, temperature, and moisture are prescribed from satellite observations. Cloud diurnal contributions to time-mean energetics arise from the nonlinear dependence of radiative fluxes on diurnally varying properties. Diurnal variations of cloud fractional coverage and solar flux are the main factors of the cloud diurnal contributions to shortwave (SW) flux, although the diurnal variation of cloud type is also important. The cloud diurnal contribution to longwave (LW) flux at the top of the atmosphere (TOA) is produced by diurnal variations of cloud fractional coverage, cloud-top height, and surface temperature. The cloud diurnal contribution to LW flux at the surface is produced by diurnal variations of cloud fractional coverage and cloud-base height. Cloud diurnal contributions to SW fluxes at the surface and TOA are much larger than the contribution to SW atmospheric absorption. The contribution to radiative heating in the atmosphere is concentrated inside the cloud layer. Its vertical profile changes sign, so the cloud diurnal contribution to atmospheric energetics is significantly larger than is implied by the column average. Cloud diurnal contributions to SW flux at the surface and TOA are 5-15 W m-2 over continental and maritime subsidence regions, where the diurnal variation of cloud fractional coverage is large. The contributions to LW fluxes are 1-5 W m-2 over continental regions, where diurnal variations of cloud fractional coverage and surface temperature are large. A cancellation between contributions of opposite sign makes the cloud diurnal contributions to globally averaged energetics much smaller than regional contributions. However, a shift in regional climate from one dominated by high clouds to one dominated by low clouds can alter time-mean surface energetics by as much as 20 W m-2."
"57197233631;6603315998;7007140803;56152167900;56275096000;","On the regional climatic impact of contrails: Microphysical and radiative properties of contrails and natural cirrus clouds",1997,"10.1007/s00585-997-1457-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0642281547&doi=10.1007%2fs00585-997-1457-4&partnerID=40&md5=3e9c6269521cfd2a2d54dfb9fc6c2149","The impact of contrail-induced cirrus clouds on regional climate is estimated for mean atmospheric conditions of southern Germany in the months of July and October. This is done by use of a regionalized one-dimensional radiative convective model (RCM). The influence of an increased ice cloud cover is studied by comparing RCM results representing climatological values with a modified case. In order to study the sensitivity of this effect on the radiative characteristics of the ice cloud, two types of additional ice clouds were modelled: cirrus and contrails, the latter cloud type containing a higher number of smaller and less of the larger cloud particles. Ice cloud parameters are calculated on the basis of a particle size distribution which covers the range from 2 to 2000 μm, taking into consideration recent measurements which show a remarkable amount of particles smaller than 20 μm. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase in the order of 1K, ranging from 1.1 to 1.2 K in July and from 0.8 to 0.9 K in October depending on the radiative characteristics of the air-traffic-induced ice clouds. Modelling the current contrail cloud cover which is near 0.5% over Europe yields a surface temperature increase in the order of 0.05 K."
"7006095466;7103119050;7201783608;7004160585;7202772927;","GEWEX Cloud System Study (GCSS) Working Group 4: Precipitating Convective Cloud Systems",1997,"10.1175/1520-0477(1997)078<0831:GCSSGW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031399069&doi=10.1175%2f1520-0477%281997%29078%3c0831%3aGCSSGW%3e2.0.CO%3b2&partnerID=40&md5=be0ed22364f3142adfaa5bed189d69d8","The authors present the objectives of the working group on precipitating convective cloud systems. These center on developing physically based parameterizations for global models in which basic research into the large-scale role of cloud systems is an important part. The approach calls on a range of expertise: cloud-resolving modeling and contributing research, observational evaluation of the model results, and tests of parameterizations in single-column models. Ongoing studies focus on oceanic cloud systems in Tropical Oceans Global Atmosphere Coupled Ocean-Atmosphere Research Experiment (TOGA COARE). First, cloud-resolving modeling of organized convection on a timescale of a few hours concentrates on momentum transport and surface fluxes. Results are evaluated against data obtained during the 22 February 1993 Intensive Observation Period, which include airborne Doppler radar measurements of a squall line. Second, multiday simulations focus on the environmental effects of cloud systems as they respond to changes in specified (observed) large-scale tendencies and sea surface temperature. In this case, observational data on the scale of the entire TOGA COARE Intensive Flux Array are used in model evaluations. Results and recommendations from the first model intercomparison workshop, as well as the next steps in the intercomparison, are summarized. In the longer term, cloud system research in Working Group 4 will contribute to the Climate Variability and Predictability-Global Ocean-Atmosphere-Land System program, as regards the large-scale effects of cloud systems up to intraseasonal timescales. Another contribution will be to space-borne measurements; for example, cloud-profiling capability will provide data critical to the comprehensive evaluation of upper-tropospheric moisture distribution in cloud-resolving models. Besides additional studies in tropical cloud systems, convection in cold air outbreaks and convection over continents have a high priority."
"57211224269;","Mountain uplift and surface temperature changes",1997,"10.1029/96GL03953","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030736029&doi=10.1029%2f96GL03953&partnerID=40&md5=19a7df482e1f877c74bd564cf1c1bade","Mountain uplift significantly affects both sea surface temperature (SST) and land surface temperature. This was studied using a coupled atmosphere/mixed layer ocean model with and without mountains. The global mean SST dropped 1.4°C with mountain uplift, mainly due to increased lower tropospheric clouds in the subtropical eastern Pacific. Increased clouds hinder solar radiation into the ocean and lower SST. The increased frequency of stratus incidence is related to subtropical anticyclones intensified by a strong temperature contrast between the continent and ocean in mountainous regions. Land surface temperature drops due to the lapse-rate effect. When this effect is eliminated, the continental interior does not become as cool with mountain uplift because clouds become fewer and the surface drier due to decreased moisture transport. Southern Asia becomes cooler because monsoon-induced precipitation wets the ground and increases clouds. Our result showed greater northern high latitude temperature changes than the previous study, indicating the importance of cloud-related feedback in paleoclimate modeling."
"56744278700;7501956187;","Linear additivity of climate response for combined albedo and greenhouse perturbations",1997,"10.1029/97GL00248","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031091482&doi=10.1029%2f97GL00248&partnerID=40&md5=4e3630b77da6d2514b53f822876bb291","Using an atmospheric general circulation model with fixed cloud amounts and microphysical properties, and coupled to a mixed-layer static ocean, we perform idealized experiments to inquire into the linear characteristics of the modeled climate system's mean response to simultaneous greenhouse and Northern Hemisphere midlatitude albedo perturbations, two forcings deemed to be important during the present times. The two forcings are chosen to be equal and opposite in the global, annual-mean such that a linear behavior would be expected to lead to a complete offset of the global, annual-mean surface temperature change, which is indeed obtained. The monthly and annual zonal-mean surface temperature, and the annual zonal-mean precipitation responses to the combined forcings, also are reasonably similar to the sum of the responses to the individual forcings. The albedo forcing case casts a distinct signature on the circulation and precipitation changes in the northern and southern equatorial regions, which is absent for the greenhouse forcing case. The combined simulation yields a result similar to that for the albedo forcing case, one that is consistent with linear additive expectations."
"7003976079;","Interannual variability of the earth's radiation budget: Some regional studies",1997,"10.1002/(sici)1097-0088(199707)17:9<929::aid-joc166>3.0.co;2-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031426006&doi=10.1002%2f%28sici%291097-0088%28199707%2917%3a9%3c929%3a%3aaid-joc166%3e3.0.co%3b2-1&partnerID=40&md5=fd309745855e48326f322201560437cb","A detailed study is presented of the interannual variability of the Earth's radiation budget (ERB) at the top of the atmosphere in three equatorial regions: the western Pacific over Indonesia, the eastern Pacific off the west coast of South America and the eastern Atlantic off the west coast of Africa. The objective is to try and understand the cloud, surface and ERB interactions that occur in these areas, each of which shows a large interannual signal in the net radiation balance. The period studied extends from March 1979 through to April 1985, for which coincident ERB and cloud data are available from the Nimbus-7 ERB and Cloud Climatology data sets. This period encompasses the exceptional 1982-1983 ENSO as well as the 1984 Atlantic warming event. Additionally, sea-surface temperature data from the Global Ocean Surface Temperature Atlas (GOSTA) data set are used in combination with the ERB data to partition the outgoing longwave radiation into surface emission and greenhouse-effect components. The methodology involves examination of the time series of anomalies in all of these quantities together with the formulation of statistical relationships amongst them. These methods firstly allow the shortwave (SW) and longwave (LW) components of the ERB anomalies to be identified. The SW and LW anomalies are themselves seen to be made up of different components and, much like the net balance, are often the residuals of two competing effects. This is exemplified in the eastern Pacific and Atlantic regions, which both experienced periods of anomalously high SSTs. In such areas the SW anomaly can arise due to an imbalance between the cooling effect of increased high cloudiness and warming due to reduction of low level cloud, whilst the LW anomaly is composed of warming due to the increase in high cloud amount and cooling due to increased surface emission. The result is that anomalies in the net balance term, which is ultimately the most important with regard to climate variability, are seen to arise as a result of complex interactions between the atmosphere, cloudiness and surface. © 1997 by the Royal Meteorological Society."
"56744278700;7501956187;","Climate forcing-response relationships for greenhouse and shortwave radiative perturbations",1997,"10.1029/97GL00253","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031091439&doi=10.1029%2f97GL00253&partnerID=40&md5=fbb17c6d0039552898d5007dcd34f053","The earth's climate system is subject to radiative forcings caused by perturbations in the infrared 'greenhouse' effect and absorbed solar energy. The forcings can be classified as being global in extent (e.g., increase of CO2) or spatially confined to the northern hemisphere midlatitudes (e.g., anthropogenic sulfate aerosols). Of central importance to climate change assessments are the characteristics of the global and latitudinal changes, and the forcing-response relationships for different kinds of perturbations. Using a general circulation climate model with fixed cloud distributions and microphysical properties, we analyze the equilibrium climate responses to different perturbations representing global and spatially localized radiative forcings. The total climate feedback in the various experiments does not differ significantly, and the global-mean climate sensitivity (ratio of the equilibrium global-mean surface temperature change to the global-mean imposed radiative forcing) behaves in a near-invariant manner for both global and spatially confined forcings. However, relative to the global perturbation cases, forcings confined to the northern hemisphere midlatitudes exhibit a steepening of the meridional gradient of the temperature response in that hemisphere."
"55708190300;6603859477;7005494775;","Calculations pertaining to hygroscopic seeding with flares",1997,"10.1175/1520-0450(1997)036<1449:CPTHSW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031395086&doi=10.1175%2f1520-0450%281997%29036%3c1449%3aCPTHSW%3e2.0.CO%3b2&partnerID=40&md5=7d57a17250c7b43b152b187e8d863a55","Some possible effects of hygroscopic seeding with flares are explored by calculating how such seeding would modify the initial size distribution of cloud droplets and the subsequent evolution of that size distribution by coalescence. To be representative of recent experiments in South Africa, the calculations emphasize the effects of hygroscopic particles that can be produced by flares, instead of the larger particles used in most past hygroscopic-seeding experiments. Parcel calculations representing simultaneous condensation and coalescence suggest that the formation of rain through the warm-rain process can be accelerated significantly by the addition of such hygroscopic particles. Some observations of the effects of hygroscopic material near cloud base support at least the early stages of the calculations. The results suggest that the positive effects being obtained in the South African experiment may occur through such acceleration of the warm-rain process. Possible cloud-seeding applications and climate implications are discussed."
"7004853382;7003353805;7005034568;6603771886;36909999000;","Cloud liquid water climatology from the special sensor microwave/imager",1997,"10.1175/1520-0442(1997)010<1086:CLWCFT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030782314&doi=10.1175%2f1520-0442%281997%29010%3c1086%3aCLWCFT%3e2.0.CO%3b2&partnerID=40&md5=d6a7d31637f49b87fb616fca32306c5c","A Special Sensor Microwave/Imager (SSM/I) algorithm is developed to measure both cloud liquid water path (LWP) and cloud frequency (CF) over the oceans. For climate analysis, the LWP and CF parameters are computed on pentad and monthly timescales. Comparisons are made between cloud frequencies obtained from microwave and visible/infrared measurements. It is shown that the SSM/I CF correlates with International Satellite Cloud Climatology Program low- and middle-level cloudiness. Interannual variations of monthly LWP are found to be strongly correlated with El Niño and La Niña events. In general, positive LWP anomalies are associated with positive SST anomalies. However, positive LWP anomalies may also occur in regions of negative SST anomalies. This is probably due to an increase in warm top rain clouds, produced from low-level convergence. When pentads of outgoing longwave radiation data are compared to the LWP, they both show the detailed structure for atmospheric intraseasonal oscillations at 30-60-day periods. However, there are some interesting differences. Finally, as an important application, the monthly LWP is compared with simulations from a general circulation model. While the simulation captures the locations of observed maxima and minima, there is a large discrepancy between the model and measurement for the Northern Hemisphere in summer."
"7005523706;7004114883;","Stratiform and convective classification of rainfall using SSM/I 85-GHz brightness temperature observations",1997,"10.1175/1520-0426(1997)014<0570:SACCOR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000204820&doi=10.1175%2f1520-0426%281997%29014%3c0570%3aSACCOR%3e2.0.CO%3b2&partnerID=40&md5=cf9cbfaad30bd31b376cfa6c0fc766e1","A better understanding of global climate calls for more accurate estimates of liquid and ice water content profiles of precipitating clouds and their associated latent heating profiles. Convective and stratiform precipitation regimes have different latent heating and therefore impact the earth's climate differently. Classification of clouds over oceans has traditionally been part of more general rainfall retrieval schemes. These schemes are based on individual or combined visible and infrared, and microwave satellite observations. However, none of these schemes report validations of their cloud classification with independent ground observations. The objective of this study is to develop a scheme to classify convective and stratiform precipitating clouds using satellite brightness temperature observations. The proposed scheme probabilistically relates a quantity called variability index (VI) to the stratiform fractional precipitation coverage over the satellite field of view (FOV). The VI for a satellite pixel is the mean absolute 85-GHz brightness temperature difference between the pixel and the eight surrounding neighbor pixels. The classification scheme has been applied to four different rainfall regimes. All four regimes show that the frequency of stratiform rainfall in the satellite FOV increases as the satellite-based VI decreases. The results of this study demonstrate that the satellite-based VI is consistently related to the probability of occurrence of three classes (0%-40%, 40%-70%, and 70%-100%) of FOV stratiform coverage."
"57206508283;7102490158;","Distribution characteristics of clouds over East Antarctica in 1987 obtained from AVHRR",1997,"10.2151/jmsj1965.75.1_81","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0039377569&doi=10.2151%2fjmsj1965.75.1_81&partnerID=40&md5=d1e079c691b15a5f0e28e3eaf0607e12","Polar cloud climatology is an urgent issue; to be solved for the study of global climate; from satellite data. However, detection of clouds in the polar regions involves many difficulties on account of the high albedo and low temperature of the snow and ice covered ground surface. Discrimination of clouds was done using AVHRR split window channel data. Brightness temperature differences of 11 μm (ch 4) and 12 μm (ch 5) were one of the indices of thin clouds; the correlation of the brightness temperature difference and the brightness temperature itself was used. Cloud amounts thus derived were well explained by the all-sky camera data measured at the ground. The cloud analysis was done from daily NOAA-9 data for thirteen months from January 1987 to January 1988, received and processed at Syowa Station, Antarctica. Spatial and temporal distribution characteristics of clouds over the East Antarctic continent are discussed. Annual mean cloud fraction ranged from 50 % to less than 10 % according to the region, being larger near the coast and smaller over the high interior plateau. Within the interior, cloud amounts were liable to be higher over the western slope facing the Weddell Sea compared to the eastern slope. Semi-annual variations were seen in most of the area related to the behavior of the disturbances. In July to September, cloud amounts in the interior increased in some regions, and in November to January, increased in most regions; however, not much variation was seen in the coastal area. The analyzed area was divided into three regions of different variation characteristics, related to the topography. An oscillation of about 7 or 15 days in the time variation of clouds was noticeable in most regions. Comparing the brightness temperature for clear and cloudy sky, the radiative effect of clouds at the top of the atmosphere was found to be negative (cooling) in winter in the interior, and small positive (heating) in the longwave in summer months over the whole area."
"7005171879;","Contrail-Cirrus and Their Potential for Regional Climate Change",1997,"10.1175/1520-0477(1997)078<1885:CCATPF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031432845&doi=10.1175%2f1520-0477%281997%29078%3c1885%3aCCATPF%3e2.0.CO%3b2&partnerID=40&md5=d4242d41244d18caad7b4a0e1b248f37","After reviewing the indirect evidence for the regional climatic impact of contrail-generated cirrus clouds (contrail-cirrus), the author presents a variety of new measurements indicating the nature and scope of the problem. The assessment concentrates on polarization lidar and radiometric observations of persisting contrails from Salt Lake City, Utah, where an extended Project First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) cirrus cloud dataset from the Facility for Atmospheric Remote Sensing has captured new information in a geographical area previously identified as being affected by relatively heavy air traffic. The following contrail properties are considered: hourly and monthly frequency of occurrence; height, temperature, and relative humidity statistics; visible and infrared radiative impacts; and microphysical content evaluated from in situ data and contrail optical phenomenon such as halos and coronas. Also presented are high-resolution lidar images of contrails from the recent SUCCESS experiment, and the results of an initial attempt to numerically simulate the radiative effects of an observed contrail. The evidence indicates that the direct radiative effects of contrails display the potential for regional climate change at many midlatitude locations, even though the sign of the climatic impact may be uncertain. However, new information suggests that the unusually small particles typical of many persisting contrails may favor the albedo cooling over the greenhouse warming effect, depending on such factors as the geographic distribution and patterns in day versus night aircraft usage."
"7005565819;7202188428;57213280540;","STORMTIPE-95: Results from a convective storm forecast experiment",1997,"10.1175/1520-0434(1997)012<0388:SRFACS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031225176&doi=10.1175%2f1520-0434%281997%29012%3c0388%3aSRFACS%3e2.0.CO%3b2&partnerID=40&md5=7ed2f48fd133945cc025feb13c00175c","During the spring of 1995, an operational forecast experiment using a three-dimensional cloud model was carried out for the north Texas region. Gridpoint soundings were obtained from the daily operational numerical weather prediction models run at the National Centers for Environmental Prediction, and these soundings were then used to initialize a limited-domain cloud-resolving model in an attempt to predict convective storm type and morphology in a timely manner. The results indicate that this type of convective forecast may be useful in the operational environment, despite several limitations associated with this methodology. One interesting result from the experiment is that while the gridpoint soundings obtained from the NCEP models generally overforecast instability and vertical wind shear, the resulting convective storm evolution and morphology in the cloud model was often similar to that of the observed storms. Therefore the ""overforecast"" of mesoscale environment's instability and vertical wind shear still resulted in a thunderstorm-scale forecast that provided useful information to operational forecasters."
"7102490158;6701859365;","Effects of clouds, ice sheet, and sea ice on the Earth radiation budget in the Antarctic",1997,"10.1029/96JD02866","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031411858&doi=10.1029%2f96JD02866&partnerID=40&md5=40e869d2a9d4d08a69189edc78518f3f","The effects of clouds, the continental ice sheet, and sea ice on the radiation budget in the Antarctic are examined by using Earth Radiation Budget Experiment, International Satellite Cloud Climatology Project, and special sensor microwave/imager data in 1987/1988. The continental ice sheet affects not only the albedo but also the surface temperature because of elevation and hence the outgoing longwave radiation (OLR). The high elevation of the Antarctic continent makes the radiation budget in both polar regions asymmetric. At elevations below 2 km the OLR is reduced at the rate of 5-10 W/m2/km; above 2 km the rate is about 20 W/m2/km. Sea ice, which is a critical climate feedback factor, appears to have less impact on radiation than do clouds. Between 60° and 65°S in October, sea ice increases the top of the atmosphere albedo by about 0.2 and reduces the OLR by 7-10 W/m2; this seems smaller than the formal cloud forcing, which increases the albedo by 0.3 and reduces the OLR by 30-40 W/m2. However, these numbers do not fully differentiate the independent effects of sea ice and cloudiness. A more detailed analysis shows that the independent effect of sea ice is as large as clouds, with clouds masking the radiative effect of sea ice by more than one half. Copyright 1997 by the American Geophysical Union."
"57212856885;7102636922;6701672112;","Impact of ocean circulation on regional polar climate simulations using the Arctic region climate system model",1997,"10.3189/s026030550001404x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031396375&doi=10.3189%2fs026030550001404x&partnerID=40&md5=e3d19f2a1c683be5cfe8be67ac9d262d","Global climate models have pointed to the polar regions as very sensitive areas in response to climate change. However, these models often do not contain representations of processes peculiar to the polar regions such as dynamic sea ice, permafrost, and Arctic stratus clouds. Further, global models do not have the resolution necessary to model accurately many of the important processes and feedbacks. Thus, there is a need for regional climate models of higher resolution. One such model (ARCSyM) has been developed by A. Lynch and W. Chapman. This model incorporates the NCAR Regional Climate Model (RegCM2) with the addition of Flato-Hibler cavitating fluid sea-ice dynamics and Parkinson-Washington ice thermodynamic formulation. Recently work has been conducted to couple a mixed-layer ocean to the atmosphere-ice model, and a three-dimensional (3-D) dynamical ocean model, in this case the S-Coordinate Primitive Equation Model (SPEM), to the ice model. Simulations including oceanic circulation will allow investigations of the feedbacks involved in fresh-water runoff from sea-ice melt and sea-ice transport. Further, it is shown that the definition of the mixed-layer depth has significant impact on ice thermodynamics."
"7201600437;57197189583;","Mechanism of multi-decadal climatic variability in a global climatic model",1997,"10.1002/(SICI)1097-0088(199705)17:6<565::AID-JOC172>3.0.CO;2-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031450833&doi=10.1002%2f%28SICI%291097-0088%28199705%2917%3a6%3c565%3a%3aAID-JOC172%3e3.0.CO%3b2-6&partnerID=40&md5=55a1fbb188551670e3cab4b8c2c4c56f","A 500-year run has been made with a global climatic model for current climatic conditions using a simple slab ocean with inferred oceanic heat transfers. The model exhibited multi-decadal warming and cooling episodes with changes in globally averaged, annual mean surface temperature of up to 0.7°C. The length of the individual episodes varied, but 50-60 years was typical for major episodes. Examination of the geographical distribution of climatic variables for warm or cool episodes revealed distinct differences, particularly of surface temperature and low-level zonal wind, with considerable activity concentrated over the low-latitude Pacific Ocean. Each multi-decadal warming and cooling episode experienced pulsations of about 3-5 years duration associated with westerly wind bursts over the western Pacific Ocean. These bursts were related to the behaviour of the Asian monsoon, and, in turn, a connection between activity over the Pacific Ocean and the Asian monsoon was identified via the global distribution of velocity potential. The wind bursts produced warmings of the low-latitude, central Pacific Ocean and showed a number of features characteristic of the atmospheric phase of an ENSO event. The centre of activity producing the multi-decadal variability was determined to be the low-latitude Pacific Ocean, and analysis was subsequently concentrated on this region. The major factor controlling the multi-decadal warming and cooling episodes was cloud variability. During a cooling episode low-level cloud amount increased whereas high-level cloud amount decreased, with both variations contributing to the overall cooling. The reverse situation applied during a warming episode. A necessary precursor to a cooling episode was a build up in low-level moisture in the atmosphere sufficient to sustain the subsequent low-level cloud amount as the cooling progressed. The termination of a cooling episode resulted from a reduction in the total cloud amount, attributed to the high-and medium-level cloud, despite the increase in low-level cloud amount. This reduction permitted sufficient solar radiation to reach the surface in low latitudes to initiate a warming and trigger deep convection and thus recharge the high-level cloud amount, which then enhanced the initial solar-induced surface warming. © 1997 by the Royal Meteorological Society."
"7004993886;","Combined global climate model and mesoscale model simulations of Antarctic climate",1997,"10.1029/97JD00792","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031408153&doi=10.1029%2f97JD00792&partnerID=40&md5=87db6eade8aa33fd26d9afe9eff55c42","Simulations of high southern latitudes with the high-resolution, limited-area Penn State/NCAR mesoscale model, version 4 (MM4), examine the impact of a moist physics parameterization and the success of a one-way nesting inside the global NCAR community climate model, version 2 (CCM2). Discretization is by 100 km resolution in the horizontal and 15 or 16 levels in the vertical. Initial and boundary conditions for the simulations are provided by analyses of the European Centre for Medium-Range Weather Forecasts or CCM2 simulations. Comparisons of dry and moist simulations of an austral winter month, June 1988, are used to examine the role of clouds in the regional meteorology. A cloud-free MM4 simulation with boundary conditions provided by CCM2 run 422 indicates that the one-way nesting of the mesoscale model can produce significant differences in the model output, including an improvement in the location of one longwave trough, reduced cold bias, and a more detailed surface wind field. The improved location of the longwave trough over the Atlantic Ocean is hypothesized to result from blocking induced by the reduced cold bias. The nested simulation is sensitive to the forcing at the horizontal boundaries. Consequently, proper location of troughs and ridges at the boundaries is required for the model to well represent all the major troughs and ridges inside the domain. The addition of moist physics to the mesoscale simulations tends to improve the quality of the simulated fields over the Southern Ocean. In particular, the intensity of the circumpolar trough is increased. Over Antarctica, serious deficiencies are found in the simulations with moist physics. Excessive moisture is apparently stored in the simulated clouds leading to excessive atmospheric back radiation and, consequently, excessive temperatures at the surface and higher up in the troposphere. Copyright 1997 by the American Geophysical Union."
"35494005000;7005626683;7006204393;35473805400;","A study of composite cirrus morphology using data from a 94-GHz radar and correlations with temperature and large-scale vertical motion",1997,"10.1029/97JD00402","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031408542&doi=10.1029%2f97JD00402&partnerID=40&md5=45a19f912e9d64891b2c7d72413252ef","In order to improve the representation of clouds in climate models, we require a better understanding of the relationship among cloud properties and the synoptic-scale state of the atmosphere. In order to investigate this issue as it pertains to a specific class of cirrus clouds, we have combined a 2 month data set of radar reflectivities observed at State College, Pennsylvania, using a W-band radar with output from a mesoscale model that uses 3-hourly data assimilation. Products of the analysis include statistical distributions of fundamental cirrus cloud properties, such as frequency of occurrence, base, top and midcloud height, and layer thickness. We also consider the relationships between cirrus reflectivity and the large-scale meteorological state defined by area-averaged temperature and vertical velocity. Overall, cirrus clouds are observed 32% of the time, and 51% of those events occur in conjunction with lower-level clouds. Most of the cirrus occur in thin layers (<1.5 km thickness). Cirrus occurrence appears to be related to large-scale meteorological factors but the relationships are complex. The majority of the cirrus we observed occurred at temperatures lower than -35°C and there is little correlation between radar reflectivity and temperature. We also used this data set to examine the usefulness of a satellite-borne W-band radar. Copyright 1997 by the American Geophysical Union."
"7102636922;7006812924;7203062127;8540777600;","A multivariate comparison of two land-surface models integrated into an Arctic regional climate system model",1997,"10.3189/s0260305500013914","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031396704&doi=10.3189%2fs0260305500013914&partnerID=40&md5=0d60d935846a6ec31d847518680d00eb","Different vegetation models impact the atmospheric response of a regional climate model in different ways, and hence have an impact upon the ability of that model to match an observed climatology. Using a multivariate principal-component analysis, we investigate the relationships between several land-surface models (BATS, LSM) coupled to a regional climate model, and observed climate parameters over the North Slope of Alaska. In this application, annual cycle simulations at 20km spatial resolution are compared with European Centre for Medium-Range Weather Forecasts (ECMWF) climatology. Initial results demonstrate broad agreement between all models; however, small-scale regional variations between land-surface models indicate the strengths and weaknesses of the land-surface treatments in a climate system model. Specifically, we found that the greater surface-moisture availability and temperature-dependent albedo formulation of the LSM model allow for a higher proportion of low-level cloud, and a later, more rapid transition from the winter to the summer regime. Crucial to this transition is the seasonal cycle of incoming solar radiation. These preliminary results indicate the importance of the land-surface hydrologic cycle in modelling the seasonal transitions."
"35509639400;7401559815;7004160106;","Sea surface temperature and large-scale circulation influences on tropical greenhouse effect cloud radiative forcing",1997,"10.1175/1520-0442(1997)010<2055:SSTALS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031200764&doi=10.1175%2f1520-0442%281997%29010%3c2055%3aSSTALS%3e2.0.CO%3b2&partnerID=40&md5=a91eda0716fe5255448df729c71487eb","Two independent sets of meteorological reanalyses are used to investigate relationships between the tropical sea surface temperature (SST) and the large-scale vertical motion of the atmosphere for spatial and seasonal variations, as well as for El Niño/La Niña episodes of 1987-88. Supergreenhouse effect (SGE) situations are found to be linked to the occurrence of enhanced large-scale rising motion associated with increasing SST. In regions where the large-scale atmospheric motion is largely decoupled from the local SST due to internal or remote forcings, the SGE occurrence is weak. On seasonal and interannual timescales, such regions are found mainly over equatorial regions of the Indian Ocean and western Pacific, especially for SSTs exceeding 29.5°C. In these regions, the activation of feedback processes that regulate the ocean temperature is thus likely to be more related to the large-scale remote processes, such as those that govern the monsoon circulations and the low-frequency variability of the atmosphere, than to the local SST change. The relationships among SST, clouds, and cloud radiative forcing inferred from satellite observations are also investigated. In large-scale subsidence regimes, regardless of the SST range, the cloudiness, the cloud optical thickness, and the shortwave cloud forcing decrease with increasing SST. In convective regions maintained by the large-scale circulation, the strong dependence of both the longwave (LW) and shortwave (SW) cloud forcing on SST mainly results from changes in the large-scale vertical motion accompanying the SST changes. Indeed, for a given large-scale rising motion, the cloud optical thickness decreases with SST, and the SW cloud forcing remains essentially unaffected by SST changes. However, the LW cloud forcing still increases with SST because the detrainment height of deep convection, and thus the cloud-top altitude, tend to increase with SST. The dependence of the net cloud radiative forcing on SST may thus provide a larger positive climate feedback when the ocean warming is associated with weak large-scale circulation changes than during seasonal or El Niño variations."
"7004593505;7004027377;","Climatic Effects of Amazonian Deforestation: Some Results from ABRACOS",1997,"10.1175/1520-0477(1997)078<0823:CEOADS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031399751&doi=10.1175%2f1520-0477%281997%29078%3c0823%3aCEOADS%3e2.0.CO%3b2&partnerID=40&md5=ab6e4014e59d5b70039fb3ac8d7f7308","This paper reviews the climatological measurements and some of the modeling in the Anglo-Brazilian Amazonian Climate Observational Study (ABRACOS) project. The local-scale, mesoscale, and large-scale climatic impacts of Amazonian deforestation are demonstrated. The difference in radiation and energy balance between forest and clearing gives higher air temperatures in the clearings, particularly in the dry season. In areas of substantial deforestation, higher sensible heat fluxes from the cleared forest produce deeper convective boundary layers, with differences in cloud cover being observed and mesoscale circulations being predicted. The use of the ABRACOS data for calibrating general circulation model land surface schemes is discussed."
"7006458649;6603614180;7005780974;6507612497;6508025840;7801535993;","Areal classification concerning patterns of global radiation and cloudiness variations in Hungary",1997,"10.1016/S0273-1177(97)00065-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030693826&doi=10.1016%2fS0273-1177%2897%2900065-3&partnerID=40&md5=58fb2c0480e4836baf7143588478168b","Factor Analysis (FA) in S-mode is applied to classify the global radiation and the cloud distribution patterns derived from METEOSAT digital images The aim of the areal classification is to construct a meta-archive of days with different cloud coverage for the derivation of surface climate parameters and also for the special needs of weather analysis. Another aim is to intercompare the large-scale patterns of global radiation, derived from the visible channel, with the other investigated parameter, the cloud covearge, that employs infrared information, too. The investigated areas cover 4x8 and 4x9 spatial elements corresponding to app. 70x70 km and 50x50 km resolution in Central Europe, respectively. Regions are defined, where for any point within each region, the analysed meteorological variable covaries. Results of the two classifications indicate a similar number, 3-5, of characteristic regions, but their spatial arrangements are different Another difference is that, for the cloudiness, the fourth rotated factor (having already been rejected according to the Guttman criterion i.e. the rule to keep the factors with eigenvalues >1) does not influence the patterns in case of cloud coverage, but yields completely different structure in case of global radiation. © 1997 COSPAR."
"56157800800;","The 1988 and 1990 summer season simulations for West Africa using a regional climate model",1997,"10.1175/1520-0442(1997)010<1255:TASSSF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031395865&doi=10.1175%2f1520-0442%281997%29010%3c1255%3aTASSSF%3e2.0.CO%3b2&partnerID=40&md5=52722a9e631a483e78e5079c36fce070","Simulations have been undertaken using a regional climate model (RegCM2) developed at the National Center for Atmospheric Research for the West African growing season (June-September) periods of 1988 and 1990. The regional climate model simulations are driven at the lateral boundaries every 12 h by data from European Centre for Medium-Range Weather Forecasts (ECMWF) analyses, with a horizontal grid spacing of 110 km using the Grell cumulus parameterization. An additional simulation during the 1988 growing season also uses the Kuo cumulus parameterization. Furthermore, a review of the differences in the tropical circulation from the ECMWF analyses during 1988 and 1990 are reviewed. The climate simulations using the Grell parameterization during the 1988 and 1990 growing seasons capture many of the observed atmospheric features and depict drier conditions during 1990. Precipitation amounts are underestimated for both the Kuo and Grell parameterizations when compared to observations during 1988, with the largest differences occurring in the Kuo parameterization. In comparison to the ECMWF analyses, both models produce a dry bias in the lower troposphere over land areas. Even with the shortcomings in the RegCM2 simulations, the model correctly develops easterly waves when compared to ECMWF analyses and observed cloud fields. The results presented here offer promise for the use of regional climate models for the study of climate variability and possibly climate change scenarios in West Africa; however, significant challenges still exist."
"7404334532;7405727977;6604021707;","Radiative forcing and climate response",1997,"10.1029/96JD03436","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031411233&doi=10.1029%2f96JD03436&partnerID=40&md5=33f6442acae9281dafef9b2964bc058d","We examine the sensitivity of a climate model to a wide range of radiative forcings, including changes of solar irradiance, atmospheric CO2, O3, CFCs, clouds, aerosols, surface albedo, and a ""ghost"" forcing introduced at arbitrary heights, latitudes, longitudes, seasons, and times of day. We show that, in general, the climate response, specifically the global mean temperature change, is sensitive to the altitude, latitude, and nature of the forcing; that is, the response to a given forcing can vary by 50% or more depending upon characteristics of the forcing other than its magnitude measured in watts per square meter. The consistency of the response among different forcings is higher, within 20% or better, for most of the globally distributed forcings suspected of influencing global mean temperature in the past century, but exceptions occur for certain changes of ozone or absorbing aerosols, for which the climate response is less well behaved. In all cases the physical basis for the variations of the response can be understood. The principal mechanisms involve alterations of lapse rate and decrease (increase) of large-scale cloud cover in layers that are preferentially heated (cooled). Although the magnitude of these effects must be model-dependent, the existence and sense of the mechanisms appear to be reasonable. Overall, we reaffirm the value of the radiative forcing concept for predicting climate response and for comparative studies of different forcings; indeed, the present results can help improve the accuracy of such analyses and define error estimates. Our results also emphasize the need for measurements having the specificity and precision needed to define poorly known forcings such as absorbing aerosols and ozone change. Available data on aerosol single scatter albedo imply that anthropogenic aerosols cause less cooling than has commonly been assumed. However, negative forcing due to the net ozone change since 1979 appears to have counterbalanced 30-50% of the positive forcing due to the increase of well-mixed greenhouse gases in the same period. As the net ozone change includes halogen- driven ozone depletion with negative radiative forcing and a tropospheric ozone increase with positive radiative forcing, it is possible that the halogen-driven ozone depletion has counterbalanced more than half of the radiative forcing due to well-mixed greenhouse gases since 1979."
"7202364010;","The annual warm to cold phase transition in the eastern equatorial pacific: Diagnosis of the role of stratus cloud-top cooling",1997,"10.1175/1520-0442(1997)010<2447:TAWTCP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031410057&doi=10.1175%2f1520-0442%281997%29010%3c2447%3aTAWTCP%3e2.0.CO%3b2&partnerID=40&md5=5753e6be5b4e656068822a3ce238047f","The forcing of the March to May southerly surface-wind tendency along the equatorial South American coast, which leads to the annual transition of the eastern tropical Pacific basin's climate from its peak warm phase in April, is explored through diagnostic modeling. Modeling experiments with a high-resolution (18 σ-levels, Δθ = 2.5°, 30 zonal waves) steady-state global linear primitive equation model that produces a striking simulation of most aspects of the March to May change in the lower tropospheric circulation over the eastern tropical Pacific, including the notable southerly surface-wind tendency, have provided unique insight into the role of various physical processes. The model is forced by the 3D distribution of the residually diagnosed diabatic heating and the submonthly momentum and thermal transients, all obtained from the twice-daily 2.5° × 2.5° European Centre for Medium-Range Weather Forecasts uninitialized analyses for 1985-95. The principal findings are the following: • The initial southerly surface-wind tendency along the equatorial South American coast in April is forced by the March to May abatement in deep heating (p ≲ 900 mb) over the Amazon due to the northward migration of continental convection, and by the elevated Andean cooling. • The increased Northern Hemisphere deep heating due to the developing Central American monsoons and the eastern Pacific ITCZ also contributes to the generation of the initial coastal southerly wind tendency, but not more strongly than the March to May cooling over South America. • The March to May cooling of the lower troposphere (600-900 mb) over the southeastern tropical Pacific, which likely results from the longwave radiative cooling from the developing stratocumulus cloud tops, generates relatively strong southerly surface-wind tendencies over the eastern Pacific, particularly at the equatorial South American coast. Based on the last finding, a new feedback mechanism can be envisioned for the rapid development of the coastal southerly surface-wind tendency and stratocumulus clouds - in which the lower tropospheric cooling over the southeastern tropical Pacific, due to longwave radiative cooling from the stratocumulus cloud tops, generates southerly surface winds, which in turn foster stratocumulus growth from the increased meridional cold advection and latent heat flux. With respect to the role of stratus clouds in the coupled annual cycle evolution, the new feedback, based on the dynamic response of cloud-top longwave cooling, should proceed more rapidly than the feedback based on the thermodynamic impact of stratus shading on SST."
"7005311892;7203059095;16637291100;7003916945;36860695100;35598959400;","AVHRR-based Polar Pathfinder products for modeling applications",1997,"10.1017/s0260305500014336","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031402911&doi=10.1017%2fs0260305500014336&partnerID=40&md5=c51bdda24719b45ae96261d05fd2d3d9","A suite of Arctic and Antarctic products is being prepared from Advanced Very High Resolution Radiometer (AVHRR) and ancillary data as part of NASA's Polar Pathfinder effort. These products consist of twice-daily gridded fields of clear-sky - surface temperature, surface albedo and cloud fraaction, as well as daily ice velocities, for 1983-96. The products and their production methodology are summarized here, with examples demonstrating applications of the Pathfinder products for process studies and modeling."
"7005513582;7005578774;","Earth's Annual Global Mean Energy Budget",1997,"10.1175/1520-0477(1997)078<0197:EAGMEB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031457607&doi=10.1175%2f1520-0477%281997%29078%3c0197%3aEAGMEB%3e2.0.CO%3b2&partnerID=40&md5=592b9e257a23118af40df3182de8592c","The purpose of this paper is to put forward a new estimate, in the context of previous assessments, of the annual global mean energy budget. A description is provided of the source of each component to this budget. The top-of-atmosphere shortwave and longwave flux of energy is constrained by satellite observations. Partitioning of the radiative energy throughout the atmosphere is achieved through the use of detailed radiation models for both the longwave and shortwave spectral regions. Spectral features of shortwave and longwave fluxes at both the top and surface of the earth's system are presented. The longwave radiative forcing of the climate system for both clear (125 W m-2) and cloudy (155 W m-2) conditions are discussed. The authors find that for the clear sky case the contribution due to water vapor to the total longwave radiative forcing is 75 W m-2, while for carbon dioxide it is 32 W m-2. Clouds alter these values, and the effects of clouds on both the longwave and shortwave budget are addressed. In particular, the shielding effect by clouds on absorption and emission by water vapor is as large as the direct cloud forcing. Because the net surface heat budget must balance, the radiative fluxes constrain the sum of the sensible and latent heat fluxes, which can also be estimated independently."
"57203346076;7003435680;","Long-term variations in insolation and their effects on climate, the LLN experiments",1997,"10.1023/a:1006579708292","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031404633&doi=10.1023%2fa%3a1006579708292&partnerID=40&md5=abc8a4f2877b7cda90f4b108bb4cc256","Used to test the Milankovitch theory over the last glacial-interglacial cycles, the Louvain-la-Neuve two-dimension Northern Hemisphere climate model shows that orbital and CO2 variations induce, in the climate system, feedbacks sufficient to generate the low frequency part of the climatic variations over the last 200 kyr. Initiation and termination of glacial cycles cannot indeed be explained without invoking both the fast feedbacks associated with atmospheric processes (water vapor, cloud, snow and sea ice) and the slower feedbacks associated with coupling to other parts of the climate system, in particular the land ice-sheet buildup and disintegration. This model shows that long-term changes in the Earth's orbital parameters lead to variations in the amount of solar radiation received at the top of the atmosphere, which in turn act as a pacemaker for climatic variations at the astronomical frequencies, through induced albedo-temperature and greenhouse gases-temperature feedbacks. Spectral analysis of the Northern Hemisphere global ice volume variations simulated under both insolation and CO2 forcings reproduces correctly the relative intensity of the peaks at the orbital frequencies as seen in SPECMAP data. Except for variations with time scales shorter than 5 kyr, the simulated long-term variations of total ice volume are comparable to that reconstructed from deep-sea cores. For example, the model simulates glacial maxima of similar amplitudes at 134 kyr BP and 15 kyr BP, followed by abrupt deglaciations."
"7102805852;7004942632;","Multi-spectral calculations of the direct radiative forcing of tropospheric sulphate and soot aerosols using a column model",1997,"10.1256/smsqj.54306","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031402566&doi=10.1256%2fsmsqj.54306&partnerID=40&md5=d8d90b8be309858a717bef812e3e5cca","A newly developed multi-spectral radiative-transfer code is used to investigate the important features of the direct radiative forcing of sulphate and soot aerosol; the indirect effect of both aerosol species is not investigated in this study. The direct radiative forcing is presented for different surface albedos, solar zenith angles, relative humidities and aerosol vertical profiles together with effects upon the surface irradiance and long-wave radiative forcing. The effect of subgrid-scale variations in relative humidity are examined using idealized relative humidity distributions. The results show that subgrid-scale variations in relative humidity and the spatial correlation between cloud and areas of high relative humidity should be considered in future general-circulation model calculations of the direct forcing due to sulphate aerosol. A comparison of the direct forcing obtained by adjusting the surface albedo to that using the full multi-spectral column calculation is performed; the results indicate that recent estimates of the climate response to the direct forcing of sulphate may be too large. The contribution to the direct forcing from cloudy-sky regions appears to be negligible for sulphate aerosol but there is a considerable enhancement of the forcing due to soot aerosol if soot exists within or above clouds. These calculations show that a small amount of soot, relative to the sulphate mass loading, can cause a significant positive direct forcing and emphasize that the vertical profile of soot aerosol relative to cloud must be established to enable accurate assessment of the direct radiative effects of anthropogenic emissions of soot aerosol."
"7402584913;7202162685;","Role of radiative transfer in the modeled mesoscale development of summertime arctic stratus",1997,"10.1029/96JD03091","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031426150&doi=10.1029%2f96JD03091&partnerID=40&md5=587dee7c22df2bb4d8b42099a9c602a4","Improvements have been made in the treatment of radiation in Version 5 of the Pennsylvania State University-National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) to simulate boundary layer stratus observed during the summertime Arctic Stratus Experiment of 1980. Shortwave radiation is treated using a two-stream, delta-Eddington approximation developed for Version 2 of the NCAR Community Climate Model. This code offers many improvements over the original radiative transfer code developed by Dudhia [1989], including a more detailed treatment of surface albedo, solar absorption by ozone, and improved treatment of liquid, ice, and mixed-phase clouds. Longwave radiative calculations are performed with the broadband radiative transfer code currently employed in Version 3 of the European Centre for Medium-Range Weather Forecasts (EC3) model. Improvements offered by EC3 include longwave radiative absorption by ozone and trace gases and the explicit radiative treatment of mixed-phase clouds. The importance of radiation in the formation of low-level Arctic stratus and the evolution of an anticyclone is illustrated with three simulations: (1) baseline simulation using the Dudhia [1989] radiative transfer, (2) improved radiative transfer (i.e., CCM2 shortwave and EC3 longwave), and (3) radiative transfer neglected. The area extent of low clouds is reduced toward observed values when improved radiative transfer is implemented. The temperature, moisture, and cloud water profiles show significant sensitivity to the treatment of radiative transfer as well. Comparisons between observations and model results show that the new radiation package improves the area extent of cloud cover and the quality of the simulated surface radiative fluxes. The importance of radiative cooling in the evolution of a Beaufort Sea anticyclone is demonstrated. Copyright 1997 by the American Geophysical Union."
"57206526682;","Sensitivity experiments performed with an energy balance atmosphere model coupled to an advection-diffusion ocean model",1997,"10.1007/BF00863779","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030976769&doi=10.1007%2fBF00863779&partnerID=40&md5=1536e29974e1537f1d023797c1d8516b","In this paper a simple climate model is presented which is used to perform some sensitivity experiments. The atmospheric part is represented by a vertically and zonally averaged layer in which the surface air temperature, radiative fluxes at the surface and at the top of the atmosphere, the turbulent fluxes between atmosphere and surface and the snow cover are calculated. This atmospheric layer is coupled to a two-dimensional advection-diffusion ocean model in which the zonal overturning pattern is prescribed. The ocean model evaluates the temperature distribution, the amount of sea-ice and the meridional and vertical heat fluxes. The present-day climate simulated by the model compares reasonably well with observations of the seasonal and latitudinal distribution of temperature, radiation, surface alebdo, sea-ice and snow cover and meridional energy fluxes. Then, the sensitivity of the model-simulated present-day climate to perturbations in the incident solar radiation at the top of the atmosphere is investigated. The temperature response displays large latitudinal and seasonal variations, which is in qualitative agreement with results obtained with other climate models. It is found that the seasonal variation of sea-ice cover (and hence, the effective oceanic heat capacity) is one of the most important elements determining seasonal variations in climate sensitivity. Differences in sensitivity between the seasonal and annual mean version of the model are discussed. Finally, the equilibrium response to perturbations in some selected model variables is presented; these variables include meridional diffusion coefficients, drag coefficient, sea-ice thickness, atmospheric CO2-concentration and cloud optical thickness."
"7005050002;7007026915;35571076700;","An empirical model to predict widespread occurrences of contrails",1997,"10.1175/1520-0450(1997)036<1211:AEMTPW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031399192&doi=10.1175%2f1520-0450%281997%29036%3c1211%3aAEMTPW%3e2.0.CO%3b2&partnerID=40&md5=aac95a1ea528c960961f832484a84c85","The increases in total cloud amount documented for large regions during the latter half of the twentieth century have focused attention on the potential contribution from jet condensation trails (contrails). The environmental conditions that favor contrail formation and persistence are not well understood primarily due to the limited number of empirical studies. This study presents an empirical model to predict widespread occurrences of contrails (outbreaks), which was developed from a combination of rawinsonde temperature and GOES water vapor information. Environments containing persisting contrails were first identified on Defense Meteorological Satellite Program satellite imagery for the United States for January and April 1987 and then analyzed in more detail using Advanced Very High Resolution Radiometer (AVHRR) satellite digital data. Adjacent clear and cloudy environments not containing contrails were identified to compare with the conditions favorable for contrail persistence. For this purpose, a predictive logistic model was developed through multiple regression analysis. The model performance was evaluated through goodness-of-fit methods and found to be statistically significant across a range of atmospheric conditions. To further evaluate the model and to demonstrate its application on a real-time basis, predictions of the probability of persisting contrails were made for a case day. Comparisons of the predictions to satellite observations of the existing conditions (using AVHRR data) demonstrate good model performance and suggest the utility of this approach for predicting persisting contrail occurrence. Implementation of this model should allow climate researchers to better quantify the influence of contrails on surface climate and natural cloud formation."
"7004423756;57197089610;6603151154;6507972168;7402755025;","Characteristics of the TOVS Pathfinder Path A Dataset",1997,"10.1175/1520-0477(1997)078<1449:COTTPP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0642339589&doi=10.1175%2f1520-0477%281997%29078%3c1449%3aCOTTPP%3e2.0.CO%3b2&partnerID=40&md5=60f46c23e146dfdcfc21634a192696ee","The TIROS (Television Infrared Observation Satellite) Operational Vertical Sounder (TOVS) Pathfinder Path A dataset is currently a 9-yr dataset, 1985-93, of global fields of surface and atmospheric parameters derived from analysis of HIRS2 and MSU data on the NOAA-9, NOAA-10, NOAA-11, and NOAA-12 polar-orbiting operational meteorological satellites. The retrieved fields include land and ocean surface skin temperature, atmospheric temperature and water vapor profiles, total atmospheric O3 burden, cloud-top pressure and radiatively effective fractional cloud cover, outgoing longwave radiation (OLR) and longwave cloud radiative forcing, and precipitation estimate. The fields are gridded on a 1° × 1° latitude-longitude grid and stored on a 1-day mean, 5-day mean, and monthly mean basis, with data from each satellite's local A.M. and P.M. orbits stored separately. Preliminary validation studies of the interannual differences of geophysical parameters derived from the TOVS Pathfinder dataset imply sufficient accuracy for their use both to study atmospheric behavior as well as to validate the ability of general circulation models to reproduce this behavior. The TOYS dataset is particularly suitable for climate studies because surface, atmospheric, cloud, and radiative parameters are all produced simultaneously in an internally consistent manner. Hence, statistical relationships between them will not be impaired by the heterogeneity inherent in data from different sources. In addition, the close agreement of OLR computed from the products with that observed by the Earth Radiation Budget Experiment enables explanation of interannual variability of OLR in terms of the variability of its component parts. The dataset is available for all users through the Goddard Space Flight Center Distributed Active Archive Center."
"7102709843;56614165400;7004879061;7405720749;","Fog forecasting for the southern region: A conceptual model approach",1997,"10.1175/1520-0434(1997)012<0545:FFFTSR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031225094&doi=10.1175%2f1520-0434%281997%29012%3c0545%3aFFFTSR%3e2.0.CO%3b2&partnerID=40&md5=157bcb01c2810cf255a59123be1285e7","The prediction of fog occurrence, extent, duration, and intensity remains difficult despite improvements in numerical guidance and modeling of the fog phenomenon. This is because of the dependency of fog on microphysical and mesoscale processes that act within the boundary layer and that, in turn, are forced by the prevailing synoptic regime. Given existing and new technologies and techniques already available to the operational forecaster, fog prediction may be improved by the development and application of a simple conceptual model. A preliminary attempt at such a model is presented for the southern region of the United States (gulf coastal states) and requires information regarding cloud condensation nuclei, moisture availability (or saturation), and dynamic forcing. Each of these factors are assessed with regard to their extent and evolution with time. An illustration, and potential application, of how the model could be used is detailed as no extensive operational testing has yet been completed. Instead, the model is applied in hindcast to verify its application. Successful use of the model will require an operational forecaster to assimilate all available tools including climatology, numerical guidance, sounding analysis, model diagnostic software, and satellite imagery. These must be used to characterize and quantify the nature of the local and regional boundary layer in the forecast region according to macroscale forcing and moisture availability, the initial local settings and boundary layer, qualitative assessment of cloud condensation nuclei, and the interaction of these in time and space. Once identified, the evolution of the boundary layer may be forecast with regard to the overall environment for fog occurrence, its likely extent, intensity, and duration."
"7003931528;57203053317;6602676272;","The atmospheric sulfur cycle in ECHAM-4 and its impact on the shortwave radiation",1997,"10.1007/s003820050163","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031415951&doi=10.1007%2fs003820050163&partnerID=40&md5=48ee9e1ccda2550da598bd1ae7f0fb4c","The atmospheric general circulation model ECHAM-4 is coupled to a chemistry model to calculate sulfate mass distribution and the radiative forcing due to sulfate aerosol particles. The model simulates the main components of the hydrological cycle and, hence, it allows an explicit treatment of cloud transformation processes and precipitation scavenging. Two experiments are performed, one with pre-industrial and one with present-day sulfur emissions. In the pre-industrial emission scenario SO2 is oxidized faster to sulfate and the in-cloud oxidation via the reaction with ozone is more important than in the present-day scenario. The atmospheric sulfate mass due to anthropogenic emissions is estimated as 0.38 Tg sulfur. The radiative forcing due to anthropogenic sulfate aerosols is calculated diagnostically. The backscattering of shortwave radiation (direct effect) as well as the impact of sulfate aerosols on the cloud albedo (indirect effect) is estimated. The model predicts a direct forcing of -0.35 Wm-2 and an indirect forcing of -0.76 Wm-2. Over the continents of the Northern Hemisphere the direct forcing amounts to -0.64 Wm-2. The geographical distribution of the direct and indirect effect is very different. Whereas the direct forcing is strongest over highly polluted continental regions, the indirect forcing over sea exceeds that over land. It is shown that forcing estimates based on monthly averages rather than on instantaneous sulfate pattern overestimate the indirect effect but have little effect on the direct forcing."
"7006432091;","Stratiform Precipitation in Regions of Convection: A Meteorological Paradox?",1997,"10.1175/1520-0477(1997)078<2179:SPIROC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031420315&doi=10.1175%2f1520-0477%281997%29078%3c2179%3aSPIROC%3e2.0.CO%3b2&partnerID=40&md5=f88e73f57794c0102f018de87ee02055","It was once generally thought that stratiform precipitation was something occurring primarily, if not exclusively, in middle latitudes - in baroclinic cyclones and fronts. Early radar observations in the Tropics, however, showed large radar echoes composed of convective rain alongside stratiform precipitation, with the stratiform echoes covering great areas and accounting for a large portion of the tropical rainfall. These observations seemed paradoxical, since stratiform precipitation should not have been occurring in the Tropics, where baroclinic cyclones do not occur. Instead it was falling from convection-generated clouds, generally thought to be too violent to be compatible with the layered, gently setding behavior of stratiform precipitation. In meteorology, convection is a dynamic concept; specifically, it is the rapid, efficient, vigorous overturning of the atmosphere required to neutralize an unstable vertical distribution of moist static energy. Most clouds in the Tropics are convection-generated cumulonimbus. These cumulonimbus clouds contain an evolving pattern of newer and older precipitation. The young portions of the cumulonimbus are too violent to produce stratiform precipitation. In young, vigorous convective regions of the cumulonimbus, precipitation particles increase their mass by collection of cloud water, and the particles fall out in heavy showers, which appear on radar as vertically oriented convective ""cells."" In regions of older convection, however, the vertical air motions are generally weaker, and the precipitation particles drift downward, with the particles increasing their mass by vapor diffusion. In these regions the radar echoes are stratiform, and typically these echoes occur adjacent to regions of younger convective showers. Thus, the stratiform and convective precipitation both occur within the same complex of convection-generated cumulonimbus cloud. The feedbacks of the apparent heat source and moisture sink of tropical cumulonimbus convection to the large-scale dynamics of the atmosphere are distinctly separable by precipitation region. The pan of the atmospheric response deriving from the areas of young, vigorous convective cells is two layered, with air converging into the active convection at low levels and diverging aloft. The older, weaker intermediary and stratiform precipitation areas induce a three-layered response, in which environmental air converges into the weak precipitation area at midlevels and diverges from it at lower and upper levels. If global precipitation data, such as that to be provided by the Tropical Rainfall Measuring Mission, are to be used to validate the heating patterns predicted by climate and general circulation models, algorithms must be applied to the precipitation data that will identify the two principal modes of heating, by separating the convective component of the precipitation from the remainder."
"7004014731;7103342287;","Sampling error in climate properties derived from satellite measurements: Consequences of undersampled diurnal variability",1997,"10.1175/1520-0442(1997)010<0018:SEICPD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030699398&doi=10.1175%2f1520-0442%281997%29010%3c0018%3aSEICPD%3e2.0.CO%3b2&partnerID=40&md5=ca1cac0208725fd4ca4d54b49706940e","The diurnal cycle present in many climate properties is undersampled in asynoptic data, which, through aliasing, introduces a bias into time-mean behavior derived from satellite measurements. This source of systematic error is investigated in high-resolution Global Cloud Imagery (GCI), which provides a proxy, with realistic space-time variability, for several climate properties to be observed from space. The GCI, which resolves mesoscale and diurnal variability on a global basis, is sampled asynoptically according to orbital and viewing characteristics from one and multiple platforms. Sampling error is then evaluated by comparing the resulting time-mean behavior against the true time-mean behavior in the GCI. The bias from undersampled diurnal variability is most serious in polar-orbiting measurements from an individual platform. However, it emerges even in precessing measurements, which drift through local time, because diurnal variability is still sampled too slowly to be truly resolved in such observations. A ""mean diurnal cycle"" can be constructed by averaging precessing measurements, provided that the ensemble of observations at individual local times is large enough (e.g., that observations are averaged over a long enough duration). The pattern of time-mean error closely resembles the pattern of error in the mean diurnal cycle. Time-mean behavior can therefore be determined only about as accurately as can the mean diurnal cycle. Determining accurate time-mean properties often requires averaging measurements from an individual platform over several months, which cannot be performed without contaminating mean behavior with seasonal variations. The sampling limitations from an individual orbiting platform are alleviated by sampling from multiple platforms, which provide observations frequently enough in space and time to determine accurate monthly mean properties."
"6701608776;7101945366;","Modification of the thermodynamic structure of the lower troposphere by the evaporation of precipitation: A GEWEX cloud system study",1997,"10.1175/1520-0493(1997)125<1431:MOTTSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000527076&doi=10.1175%2f1520-0493%281997%29125%3c1431%3aMOTTSO%3e2.0.CO%3b2&partnerID=40&md5=ab8cf4591465a0b212f71716506fa96c","The importance of subcloud evaporation to the thermodynamics and movement of cold fronts is investigated through inclusion of an explicit cloud scheme within a 30-km resolution limited-area model. Two cases are examined: 18 November 1984 and 26 February 1995. The effect of the subcloud evaporation is deduced by comparing simulations with and without the evaporation for these two cases. The implications of these results for weather prediction and climate models are discussed. The first case occurred during the Australian Cold Fronts Research Programme with mesoscale data available to verify the model simulation. The results indicate that the movement of the synoptic cold front was retarded when a prefrontal cool change developed in response to the evaporation of the grid-resolved precipitation. However, the cooling ahead of the front effectively accelerated the cool change, more in line with observations. The second case involved the prognoses of a cool change crossing Victoria in southeast Australia during a potential bushfire day. In this case, most of the precipitation occurred along and behind the cold front. With precipitation evaporation, the cool change accelerated several hundred kilometers farther in 36 h than in the simulation without precipitation evaporation."
"7006105535;","The response of cloudiness in the Atlantic-European section to the interannual variability of the North Atlantic Oscillations",1997,"10.1007/BF02523666","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031429087&doi=10.1007%2fBF02523666&partnerID=40&md5=971d1e4579d0c34aa7791fd0ca27ab78","The paper discusses the conditions corresponding to the largest and smallest North Atlantic Oscillations (NAOs). It is shown that in winter, when NAOs are at a minimum, the number of cyclones over the Black Sea increases. At the same time, cloudiness in the Atlantic-European section becomes heavier, compared with the largest NAO. Heavy cloudiness over the Balkan and Karpaty mountains, with NAO at a minimum, may imply the greater likelihood of Balkan cyclones' penetration into the Black Sea region. The mechanism responsible for the generation of maximum (minimum) cloudiness in the Atlantic-European section is discussed."
"7003679645;","The diurnal cycle of surface air temperature in simulated present and doubled CO2 climates",1997,"10.1007/s003820050181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000577498&doi=10.1007%2fs003820050181&partnerID=40&md5=6213ae654ad7a67cd768e5e092477236","The diurnal range of surface air temperature (rTa) simulated for present and doubled CO2 climates by the CSIRO9 GCM is analysed. Based on mean diurnal cycles of temperature and surface heat fluxes, a theory for understanding the results is developed. The cycles are described as the response to a diurnal forcing which is represented well by the diurnal mean flux of net shortwave radiation at the surface (SW) minus the evaporative (E) and sensible (H) fluxes. The response is modified by heat absorbed by the ground, and by the cycle in downward longwave (LW) radiation, but these effects are nearly proportional to the range in surface temperature. Thus in seasonal means, rTa is approximately given by SW-E-H divided by 6 W m-2/°C. A multiple regression model for (rTa) is developed, based on quantities known to influence SW, E and H, and applied to both spatial variation in seasonal means, and day-to-day variation at a range of locations. In both cases, rTa is shown to be influenced by cloud cover, snow extent and wind speed. It is influenced by soil moisture, although this effect is closely tied to that of cloud. In seasonal means rTa is also well correlated with precipitable water, apparently because of the latter's influence on E + H. The regression model describes well the spatial variation in the doubled CO2 change in rTa. The annual mean change in rTa over land on doubling CO2 was -0.36°C, partly because of a decrease in the mean diurnal forcing (as defined in the theory), but also apparently because of the effect of nonlinearity in Ts of the upward longwave emission. A diagnostic radiation calculation indicates that the CO2 and water vapour provide a small increase in rTa through the downward LW response, which partially counters a decrease due to a reduction of SW by the gases."
"7102953444;57202413846;7004109472;","GCM-simulated surface energy fluxes in climate change experiments",1997,"10.1175/1520-0442(1997)010<3093:GSSEFI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031393859&doi=10.1175%2f1520-0442%281997%29010%3c3093%3aGSSEFI%3e2.0.CO%3b2&partnerID=40&md5=eee4872904029a0a30a3be4c1b3b128f","The changes in the surface energy fluxes calculated with a general circulation model under increased levels of carbon dioxide concentration are analyzed and related to the simulation of these fluxes under present-day conditions. It is shown that the errors in the simulated fluxes under present climate are often of similar or larger magnitude than the simulated changes of these quantities. A similar relationship may be found in climate change experiments of many GCMs. Although this does not imply that the projected changes of the fluxes are wrong, more accurate absolute values would improve confidence in GCM-simulated climate change scenarios. The global mean increase in the downward component of the longwave radiation, which is the direct greenhouse forcing at the surface, is on the order of 10 W m-2 at the time of double carbon dioxide in a transient coupled atmosphere-ocean scenario experiment. This is an amount similar to the underestimation of this quantity in the present-day simulations compared to surface observations. Thus, it is only with doubled carbon dioxide concentration that the simulated greenhouse forcing at the surface reaches the values observed at present. The simulated shortwave radiation budget at the surface is less affected by the increased levels of carbon dioxide than the longwave budget on the globel scale. Regionally and seasonally, the changes in the incoming shortwave radiation at the surface can exceed 20 W m-2, mainly due to changes in cloud amounts. The projected changes, however, are generally of smaller magnitude than the systematic control run at the majority of 720 observation sites. The positive feedback between excessive radiation and surface processes leading to excessive summer dryness and temperatures over continental surfaces in the control run is enhanced in the doubled carbon dioxide experiment, resulting in a massive increase in the projected surface temperature. In the high-resolution T106 time-slice scenario experiment performed in this study the global mean latent heat flux and associated intensity of the hydrological cycle is slightly decreased rather than increased with doubled carbon dioxide. A reduction in surface wind speed in the T106 scenario is suggested as a major factor for the revers of sign. The improved representation of the orography with T106 resolution allows a better estimate of the projected changes of surface energy fluxes in mountain areas, as demonstrated for the European Alps."
"7402093416;6603821988;6701620324;","Sensitivity of ozone and temperature to vertical resolution in a GCM with coupled stratospheric chemistry",1997,"10.1256/smsqj.54112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031417237&doi=10.1256%2fsmsqj.54112&partnerID=40&md5=0ae18ab319993b3d333983c6424c8c3e","Results are presented from a general-circulation model with comprehensive stratospheric photochemistry and which includes the coupling between radiative heating and simulated ozone. Each model integration covers the 60-day period beginning 15 January during which episodes of polar stratospheric clouds (PSCs) are normally observed in the Arctic. Results from two versions of the model with different numbers of atmospheric levels near and above the tropopause are compared with observations. In the 19-level model the ozone transport is poorly simulated and, in particular, there is a significant increase in the tropospheric column. In contrast, in the 49-level model the simulated ozone distribution is in good general agreement with observations and reproduces well the steep vertical gradients in ozone mixing ratios in the tropical lower stratosphere, and the weak vertical gradients in the high-latitude middle stratosphere. This version also maintains a virtually constant tropospheric ozone column. Since in the 49-level model the ozone distribution is well simulated, including this ozone in the radiation calculation has only a moderate influence on the results. However, with the 19-level model, it substantially increases the global stratospheric temperature error. Increasing the number of levels improves the simulation of stratospheric temperatures but the zonal-mean temperatures in both versions of the model are generally lower than observed. Despite this, the modelled frequency of occurrences of PSCs is less than observed because of the underprediction of the zonally asymmetric component of the temperature distribution. The results suggest that if coupled chemistry-climate simulations are to proceed, it is important to have both a high upper boundary and good vertical resolution in the lower stratosphere to ensure a realistic meridional circulation and a more accurate representation of ozone transport across the tropopause."
"7404586141;","An analysis of thermal stress of climate in Hong Kong",1997,"10.1111/1467-9493.00017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-5544326645&doi=10.1111%2f1467-9493.00017&partnerID=40&md5=d51976d51f7c634bbcff91e9a62b548f","The universal scale of apparent temperature (AT) and clo, a unit measuring the amount of clothing insulation required to maintain comfort, were used to examine the weather stress in Hong Kong. Hourly AT and clo values were computed using hourly air temperature, wind speed, vapour pressure and cloud cover data from 1980 to 1994. Results of both AT and clo reflected highly corresponding changes of thermal stress. It is found that the most stressful time in winter and summer occurred in the early morning and afternoon, and cool weather and tropical ensembles were required to surmount the extreme weather stress respectively. A greater percent of time with severe heat stress than those with extreme cold stress was discovered. These results also indicated that clo is a more informative weather stress index than AT since it provides both the thermal stress and clothing requirements to sustain comfort."
"6602326421;56283400100;","Rôle of the oceanic heat transport in climate dynamics a sensitivity study with an atmospheric general circulation model",1997,"10.3402/tellusa.v49i3.14676","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030764723&doi=10.3402%2ftellusa.v49i3.14676&partnerID=40&md5=a5dd140e75fd0f9a733c2ac9bfdbedaa","Estimating meridional ocean heat transport from the present generation of atmospheric general circulation models, assuming energetic equilibrium, leads to a large variety of results, depending on the model. The current uncertainty on such an important process may cause significant errors in coupled atmosphere/ocean models. To determine the possible nature of these errors, we investigate how the prescription of the oceanic heat transport can affect the results of a coupled surface ocean/atmosphere model where the ocean is limited to thermodynamics and turbulent fluxes but sea-ice is included. In particular, we study the response of the surface fluxes and atmospheric transport to a reduction of the ocean transport. We focus on the initial phase, where these feedback effects begin to develop while the model is still realistic. The model response is strongly dependent on a combination of features: changes in the Hadley cell circulation, the atmospheric heat transport, the radiative and turbulent fluxes at the surface, changes of the radiative fluxes at the top of the atmosphere. In this study, we examine the partitioning between these different effects. It is shown that the atmosphere partly takes up the missing ocean transport, but that this leads to a change in the cloud/radiative equilibrium of the ITCZ region."
"7102038796;7202259586;7402271284;7003973306;","A changing temperature response with elevation for Lagarostrobos franklinii in Tasmania, Australia",1997,"10.1023/a:1005322332230","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030857856&doi=10.1023%2fa%3a1005322332230&partnerID=40&md5=b984a6d5c834cc7609cd312c661a8280","A network of seven Huon pine-ring width chronologies is constructed from sites ranging in elevation from 200 to 950 metres above sea level in western Tasmania. The chronologies are analysed individually and collectively to explore Huon pine's response to climate as a function of elevation. Three chronologies from greater than 700 metres in elevation exhibit a strong direct response to temperature for most growing season months (p<0.05), while three from below 700 metres exhibit a weaker, direct response to growing-season temperature, and a strong, inverse relationship with temperature of the prior season of growth, also significant at the 0.05 level. Moisture availability at these temperature rainforest sites is less growth-limiting than temperature, and significant correlations for January (inverse) and April (direct) of the year of growth largely reflect the inter-relationships between temperature, precipitation and cloudiness, and their combined influence on photosynthesis, particularly at higher-elevation sites. A rotated Principal Component Analysis reveals a clear grouping of the high and low-elevation chronologies, represented by the first and second eigenvectors, respectively. The 700 metre Lake Marilyn Low chronology is revealed to be a transitional site between the two groupings, and likely reflects an important climatic ecotone where both temperature and photosynthetically-active radiation drop below optimum levels for the species, and begin to directly inhibit growth. Tasmania's west coast climate has been shown to exhibit a distinct vertical structure, exemplified by a subsidence-inversion layer above 900 metres. Temperature increases slightly with altitude above 930 metres (the elevation at which a peak in daily minimum and maximum humidity levels is observed) before decreasing again. A dense, orographically-generated cloud-zone of reduced light and temperature has a mean altitude between 700 and 900 metres, with the steepest drop in both air and soil temperature exhibited between 850 and 930 metres. This structure can account for Huon pine's changing response to climate with elevation as described in this paper, and reinforces the importance of careful site selection for dendroclimatic research. In the case of reconstructing warm-season temperature from Tasmanian Huon pine, the desired signal might be maximised through sampling at the few rare, subalpine stands which have been located in western Tasmania. The great length afforded by the low-elevation Huon pine resource may ultimately yield a far more detailed reconstruction of regional climate throughout the Holocene, with respect to a vertical profile, following the development of more sound, mechanistically-based response models."
"6603875926;10143232600;6603906450;","Adjustment and feedbacks in a global coupled ocean-atmosphere model",1997,"10.1007/s003820050179","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031396246&doi=10.1007%2fs003820050179&partnerID=40&md5=ab2fb73f21fdc293da5fcb0e91fab473","We report the analysis of two 20-year simulations performed with the low resolution version of the IPSL coupled ocean-atmosphere model, with no flux correction at the air-sea interface. The simulated climate is characterized by a global sea surface temperature warming of about 4°C in 20 years, driven by a net heat gain at the top of the atmosphere. Despite this drift, the circulation is quite realistic both in the ocean and the atmosphere. Several distinct periods are analyzed. The first corresponds to an adjustment during which the heat gain weakens both at the top of the atmosphere and at the ocean surface, and the tropical circulation is slightly modified. Then, the surface warming is enhanced by an increase of the greenhouse feedback. We show that the mechanisms involved in the model share common features with sensitivity experiments to greenhouse gases or to SST warming. At the top of the atmosphere, most of the longwave trapping in the atmosphere is driven by the tropical circulation. At the surface, the reduction of longwave cooling is a direct response to increased temperature and moisture content at low levels in the atmospheric model. During the last part of the simulation, a regulation occurs from evaporation at the surface and longwave cooling at TOA. Most of the model drift is attributed to a too large heating by solar radiation in middle and high latitudes. The reduction of the north-south temperature gradient, and the related changes in the meridional equator-to-pole ocean heat transport lead to a warming of equatorial and subtropical regions. This is also well demonstrated by the difference between the two simulations which differ only in the parametrization of sea-ice. When the sea-ice cover is not restored to climatology the model does not maintain sea-ice at high latitudes. The climate warms more rapidly and the water vapor and clouds feedback occurs earlier."
"6604069338;56025443000;","Rainfall and convective rainfall in Catalonia, Spain",1997,"10.1002/(SICI)1097-0088(199712)17:15<1683::AID-JOC220>3.0.CO;2-Q","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031411883&doi=10.1002%2f%28SICI%291097-0088%28199712%2917%3a15%3c1683%3a%3aAID-JOC220%3e3.0.CO%3b2-Q&partnerID=40&md5=12b130d89ce33583b5aa0b1f3b3c4f4e","A substantial percentage of the total rainfall amount in Catalonia (north-east of Spain) stems from connective cloud systems. To obtain a quantitative estimate, convective events were identified on the charts of a nun-rate recorder from 1960 to 1979. Events were classified intoo four categories: non-convective, convective with low rainfall rates, convective with moderate to high mes and thunderstorn events. The amount of rain due to each of these was computed. The ration of convective to total rainfall amounts ranges from 70 to 80 per cent in the summer months to less than 30 per cent in winter and its pattern through the year is discussed as regards regional weather and climate. Orographical features, potential instability of the atmosphere and high sea-surface temperatures are related to high-rate events. The uncertain character of rainfall in the area is clearly linked to the large share of connective rainfall on the bulk precipitation © 1997 Royal Meteorological Society Int."
"7007039835;7405763496;57204346059;","The NCEP Regional Spectral Model: An Update",1997,"10.1175/1520-0477(1997)078<2125:TNRSMA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031411708&doi=10.1175%2f1520-0477%281997%29078%3c2125%3aTNRSMA%3e2.0.CO%3b2&partnerID=40&md5=1ae16aeecf7b4a3039ea61458e499445","The National Centers for Environmental Prediction (NCEP)/Environmental Modeling Center regional spectral model (RSM) has been improved in several aspects since Juang and Kanamitsu. The major improvements of RSM are its efficiency and functionality. The change of the map factor in the semi-implicit scheme from a mean value to maximal value over the regional domain, the relaxation of the lateral boundary from explicit method to implicit method (or simple blending), and the local diffusion over areas of strong wind allowed the doubling of the model computational time step. The model physics was upgraded with the improvements in the operational global spectral model (GSM) and with an additional explicit cloud scheme. An option to run in either hydrostatic or nonhydrostatic mode has been introduced. Another option to run on a CRAY machine or on a workstation has been fully tested. The nesting process has been changed to provide the capability of nesting into a coarse-resolution RSM, besides the GSM, in a one-way fashion. Thus, multinesting becomes possible, even with different map projections. Regional data assimilation with a gridpoint version of statistical interpolation and the three-dimensional variational method on sigma surfaces has been incorporated. All the output has been encoded in GRIB format, so it can be read on different machines. The authors have tested the improved functionalities of the RSM over a broad range of applications, at resolutions between 80 and 10 km. The daily routine experimental forecasts over North America have acceptable performance. Because the perturbation method, used in the RSM, results in smaller computational error than the full field method, and because the consistency between the GSM and RSM allows for a better treatment of the lateral boundary, the RSM could be used to enhance the reanalysis and regional climate simulations that have long-range integrations. The RSM is also used in the regional ensemble experiments at NCEP. The model was also applied in case studies, such as, the case of PYREX in the regional COMPARE project. Several institutions both in the United States and overseas started using the RSM, mostly for regional short-range forecast and climate modeling studies. The RSM has been scheduled to implement into operations at NCEP to possibly enhance the guidance on aviation and on daily weather forecast over Hawaii. The current version of the RSM is available to any institution requesting from the director of NCEP."
"6603074056;56088026700;7006084226;","Paleoevaporation and Paleoprecipitation in the Tanganyika Basin at 18,000 Years B.P. Inferred from Hydrologic and Vegetation Proxies",1997,"10.1006/qres.1996.1879","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031459727&doi=10.1006%2fqres.1996.1879&partnerID=40&md5=f750067e18d4a601361935a71cac18c4","Paleo-hydrologic and -vegetation proxy data from the Tanganyika basin are integrated in energy and water balance equations to infer past evaporation and precipitation during the last glacial maximum (LGM). Our approach is first validated on the modern system. Large variations are assigned to input variables to simulate the interannual precipitation variability. Equations are then applied to the LGM. We first change those input parameters inferred from proxies (basin and lake surfaces, temperature, and land albedo). Our LGM simulation suggests (in percent of modern mean values) decreases in evaporation from the lake [E1: -5% (between -13% and +3%)] and land [Ec: -8% (-19/+5)] bodies, in precipitation [P: -11% (-21/0)] and (P - Ec): -42% (-44/ -40). Decreases in P and E are amplified [E1: -8% (-16/0); Ec: -14% (-24/-2); P: -17% (-26/-6)] when including empirical changes in atmospheric transmission coefficient and Bowen ratio. Sensitivity runs suggest that even large changes in cloud cover and air humidity should not modify these trends. The results suggest that the Earth's glacial/interglacial boundary conditions play a significant role on climate of subequatorial southern Africa. © 1997 University of Washington."
"7006729638;57209596880;35588922700;6701469355;","Atmospheric boundary-layer fluxes and structure across a land-sea transition zone in South-eastern Africa",1997,"10.1023/A:1000295700599","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031285294&doi=10.1023%2fA%3a1000295700599&partnerID=40&md5=516317230e5a2dad263a5c6e18738625","The structure of the lower atmospheric boundary layer along the southeastern escarpment of Africa during November 1993 is investigated. The study region falls in a transition zone between dry desert to the west and sub-humid vegetated areas bordering the Agulhas Current to the east. The physical environment is described by in situ observations from aircraft and a coastal weather station; from satellite composites of sea surface temperature, vegetation reflectance and cloud temperatures; and synoptic weather data. Example aircraft sections illustrate sharp spatial gradients and changes in surface heat fluxes of order 100 W m-2 (10 km)-1. Inland penetration of moisture depends on background zonal winds and depth of the marine layer. Aircraft turbulent covariance estimates are used to identify high surface heat fluxes over the inland Karoo desert. During easterly winds, moisture fluxes are greatest over vegetated coastal mountains in a plume 2 km deep. Surface moisture fluxes over the Agulhas Current and coastal mountains are double those over the cold inshore waters and inland desert. The injection of moist unstable air increases the convective potential during ridging anticyclone weather conditions."
"7004890737;7005961973;6603323628;6506907349;7003489055;","The importance of direct readout satellite data in sub-synoptic scale data assimilation and numerical weather prediction",1997,"10.1016/S0273-1177(97)00049-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030680911&doi=10.1016%2fS0273-1177%2897%2900049-5&partnerID=40&md5=d0a08099664447dfe60344fc1cf831b8","Observations, directly read out from polar orbiting and geostationary satellites are vital to sub-synoptic scale analysis and forecasting over the Australian Region. Physically based methods are used for determining temperature, moisture and total ozone from NOAA satellite radiance observations from the High Resolution Infrared Sounder (HIRS), Microwave Sounding Unit (MSU) and Solar Backscatter Ultraviolet Radiometer (SBUV/2) instruments. Physical methods have also been used to estimate wind at hourly intervals from visible and infrared observations from the Geostationary Meteorological Satellite (GMS-5). The quality of these observations and their impact on forecasts in the Australian Region are documented. The studies reported here show the importance of TIROS Operational Vertical Sounder (TOVS) data to forecasting and that, in particular cases, their impact is pivotal. The benefits of a two-instrument approach, using the SBUV/2 and HIRS for estimating total ozone amount is also shown. The studies have also quantified the utility of both visible and infrared image-based hourly cloud motion vectors on forecasts, using conventional intermittent (cycling) and continuous (nudging and variational) data assimilation techniques. The vital role which these high temporal and spatial resolution wind data can play in tropical cyclone forecasting is also shown."
"7006592026;56853406500;","Representation of heterogeneity effects in earth system modeling: Experience from land surface modeling",1997,"10.1029/97rg01754","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031429652&doi=10.1029%2f97rg01754&partnerID=40&md5=86d1073d41f2b0a0fa6be2b78ae76ea6","The land surface is characterized by pronounced spatial heterogeneity that spans a wide range of scales. This heterogeneity affects the surface energy and water budgets, as well as the land-atmosphere exchanges of momentum, heat, water and other constituents, through a number of highly nonlinear processes. The resolution of present-day Earth (or climate) system models is still too coarse to explicitly capture the effects of surface heterogeneity, which therefore needs to be parameterized within the framework of complex and nonlinear land surface process schemes. The effects of surface heterogeneity are here grouped in two categories, which we define as ""aggregation"" and ""dynamical"" effects. Models of aggregation effects attempt to calculate the contribution of different subgrid scale surface types to the grid box average energy and water budgets and surface-atmosphere exchanges. Such models have been based on discrete approaches, whereby heterogeneity is described in terms of a finite number of subgrid ""tiles"" or ""patches,"" and on continuous approaches, in which heterogeneity is described in terms of probability density functions. Subgrid scale aggregation has been shown to especially affect the surface latent and sensible heat fluxes, the simulation of snow, and the dynamics of soil moisture and runoff. Dynamical heterogeneity effects are associated with microscale and mesoscale circulations induced by heterogeneous surfaces. These circulations can influence boundary layer structure, cloud formation, precipitation, and vertical transfer of momentum, energy, and water up to the midtroposphere. In the last decade or so, the importance of land surface heterogeneity representation has been increasingly recognized in a large number of new studies. This paper reviews and critically discusses different approaches that have been proposed to represent aggregation and dynamical effects of surface heterogeneity and their incorporation in land surface process schemes. Some of the methodologies discussed in this paper are of general nature and therefore can be of interest for problems of subgrid scale process description in other geophysical disciplines."
"7005619103;","CART regression models for predicting UV radiation at the ground in the presence of cloud and other environmental factors",1997,"10.1175/1520-0450(1997)036<0531:CRMFPU>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031474704&doi=10.1175%2f1520-0450%281997%29036%3c0531%3aCRMFPU%3e2.0.CO%3b2&partnerID=40&md5=e5777fc344dcb887441b48f4f2887925","The goal was to build models for predicting ground-level biologically weighted ultraviolet radiation (UV index, shortened to UV here) that would not require substantial execution time in weather and climate models and yet be reasonably accurate. Recent advances in modeling data make this goal possible. UV data computed from Brewer spectrophotometer measurements at Toronto were matched with observed meteorological predictors for 1989-93. Data were stratified into three sets by solar zenith angle 70° and time between 1000 and 1400 LST. Stepwise linear regression (SLR) and CART (nonlinear) tree-based regression models were built for UV and N(UV) (ratio: observed UV to clear-sky UV). CART models required fewer predictors to achieve minimum error, and that minimum was lower than SLR. For zenith angle less than 70° CART regression models were superior to SLR by 5%-10% error after regression. The CART model had 31% relative error (ratio: estimated mean-squared error after regression to sample variance) and three predictors: total opacity, liquid precipitation, and snow cover. Including five next predictors decreased error only another 1%. For zenith angle 70° or greater, SLR could not produce a useful model, whereas CART gave a model with 15% relative error using three predictors. Total opacity is by far the most important predictor throughout. Snow cover enhances UV at the ground by 11%-13% even in cloudy conditions, but its relative influence decreases with zenith angle. For general use at other locations models with as few predictors as possible are desirable. CART models with 34%-35% relative error were built with three predictors: total opacity, zenith angle, and clear-sky UV. Tests were done at 11 stations for several months in 1995. Averaged root-mean-squared discrepancy between predicted and observed UV is reduced about 40% when observed opacity is used for the CART prediction compared to using clear-sky UV. When an 18-h forecast opacity is used the reduction is about 25%. Improvement over clear-sky UV is substantially greater than this on cloudy days. Thus, CART three-predictor models for N(UV) can be used poleward of Toronto in a variety of cloud conditions in analysis or forecast modes. A predictor representing smoke from forest fires was not included. Several cases during the test period showed clear-sky UV was reduced by smoke 30%-50% near to the fires and 20%-30% far downwind."
"6701540733;","Multiple equilibria in radiative-convective atmospheres",1997,"10.3402/tellusa.v49i4.14681","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031399189&doi=10.3402%2ftellusa.v49i4.14681&partnerID=40&md5=37e032921d5f1834fdd30206c03ff206","A one-dimensional, radiative-convective model is used to study the equilibria conditions of moist atmospheres. We show that when the hydrologic cycle is included in the model a subcritical bifurcation occurs, leading to 2 linearly stable solutions to the radiative-convective equilibria. In this case, when the net forcing is larger than a critical value, two equilibria are possible. Furthermore, a finite amplitude instability can lead to a runaway greenhouse regime when the solar forcing is larger than a second critical value. In general, previous climate studies with radiative-convective models did not include a hydrologic cycle. Instead, the atmosphere's water vapor mixing ratio was diagnosed based on the climatological profile of relative humidity. We show that fixing the water vapor relative humidity profile at the climatological value (in the computation of the radiation fluxes only) leads to a unique stable solution to the radiative-convective equilibria. Thus, the crucial part of the hydrologic cycle which allows multiple solutions is the relaxation of the assumption of a climatological relative humidity profile. Our results do not apply directly to any real planet because of large uncertainties in our calculation due to the absence of clouds and the use of a one-dimensional model. The 1st equilibrium corresponds to an optically thin atmosphere. In this regime, the system is nearly linear and is in a state of small dissipation. The 2nd equilibrium corresponds to an optically thick atmosphere. In this 2nd regime, the system is highly nonlinear and is in a state of large dissipation."
"7402363038;7404803784;7103291058;7403681584;7006256622;7102486629;7006245928;","Annual cycle and ENSO in a coupled ocean-atmosphere general circulation model",1997,"10.1175/1520-0493(1997)125<0680:ACAEIA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001493830&doi=10.1175%2f1520-0493%281997%29125%3c0680%3aACAEIA%3e2.0.CO%3b2&partnerID=40&md5=4369c70e4df9522ccc600bd0713f2722","Results from multiyear integrations of a coupled ocean-atmosphere general circulation model are described. The atmospheric component is a rhomboidal 15, 18-level version of the Center for Ocean-Land-Atmosphere Studies atmospheric general circulation model. The oceanic component is the Geophysical Fluid Dynamics Laboratory ocean model with a horizontal domain extending from 70°S to 65°N. The ocean model uses 1.5° horizontal resolution, with meridional resolution increasing to 0.5° near the equator, and 20 vertical levels, most in the upper 300 m. No flux adjustments are employed. An initial multiyear integration showed significant climate drift in the tropical Pacific sea surface temperatures. Several modifications were made in the coupled model to reduce these errors. Changes were made to the atmospheric model cloudiness parameterizations, increasing solar radiation at the surface in the western equatorial Pacific and decreasing it in the eastern Pacific, that improved the simulation of the time-mean sea surface temperature. Large errors in the wind direction near the western coast of South America resulted in large mean SST errors in that region. A procedure to reduce these errors by extrapolating wind stress values away from the coast to coastal points was devised and implemented. Results from the last 17 years of a 62-yr simulation are described. The model produces a reasonably realistic annual cycle of equatorial Pacific sea surface temperature. However, the upper-ocean thermal structure has serious errors. Interannual variability for tropical Pacific sea surface temperatures, precipitation, and sea level pressure that resemble the observed El Niño-Southern Oscillation (ENSO) in structure and evolution is found. However, differences from observed behavior are also evident. The mechanism responsible for the interannual variability appears to be similar to the delayed oscillator mechanism that occurs in the real climate system. The structure of precipitation, sea level pressure, and geopotential anomalies associated with the tropical Pacific sea surface temperature interannual variability are isolated and described. The coupled model is capable of producing structures that are similar to those observed. It is concluded that atmosphere-ocean general circulation models are beginning to capture some of the observed characteristics of the climatology of the tropical Pacific and the interannual variability associated with the El Niño-Southern Oscillation. Remaining obstacles to realistic simulations appear to include ocean model errors in the eastern equatorial Pacific, errors associated with cloud-radiation interactions, and perhaps errors associated with inadequate meridional resolution in the atmospheric model equatorial Pacific."
"7007026915;55494073400;","Synoptic climatology, and intrahemispheric associations, of cold air mesocyclones in the Australasian sector",1997,"10.1029/96JD03357","https://www.scopus.com/inward/record.uri?eid=2-s2.0-16444372179&doi=10.1029%2f96JD03357&partnerID=40&md5=8cc5f0d1924832e1097a7e975f7508aa","Satellite IR images for seven months in 1992 are interpreted for cold air mesoscale cyclones (mesocyclones) occurring in the Australasian sector (∼70°E-150°W) of the Southern Ocean. Time-averaged (monthly, seasonal) distributions of mesocyclogenesis, mesocyclolysis, and tracks of movement, along with statistical summaries of mesocyclone attributes (e.g., cloud vortex size, speeds of movement), are presented and discussed in the context of the larger-scale atmospheric circulation. Maximum frequencies of mesocyclones occurred in the transitional months of April and October 1992, with a secondary peak in July. Statistically significant differences in mesocyclone track length between months appear related dominantly to changes in speed of the background flow, associated with the semiannual oscillation (SAO) of tropospheric pressure/height. The associations of mesocyclone ""outbreaks"" with composite anomaly fields of pressure and height are identified for three subareas of the Australasian sector suggested by the analysis of mesocyclone spatial patterns. Outbreaks occur in the strong southerly geostrophic airflow located between pressure and height anomalies that are negative (positive) to the eastward (westward). When outbreaks occurred in the New Zealand subarea in 1992, a similarly strong couplet of pressure/height anomalies developed in the southern South America/ Antarctic Peninsula sector but not when outbreaks occurred south of Australia. The mesocyclone remote association that is suggested is evaluated by using polar orbiter IR imagery for the southeastern Pacific region. Frequencies of mesocyclones increase (decrease) west of Chile but decrease (increase) through Drake Passage when mesocyclone outbreaks occur near New Zealand (south of Australia). These long distance associations of mesocyclone outbreaks are consistent with the connectivity of the baroclinic waves and might prove useful in the development of techniques to forecast mesocyclones over the Southern Ocean. Copyright 1997 by the American Geophysical Union."
"6701676466;","Effect of Temperature on Pupal Development and Eclosion Dates in the Reindeer Oestrids Hypoderma tarandi and Cephenemyia trompe (Diptera: Oestridae)",1997,"10.1093/ee/26.2.296","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0010537743&doi=10.1093%2fee%2f26.2.296&partnerID=40&md5=07210204c50857c3215d3b0a9e18d22b","The length of the pupal stage in the warble fly, Hypoderma (=Oedemagena) tarandi (L.) (n = 1,539 pupae), and the bot fly, Cephenemyia trompe (Modeer) (n = 263 pupae) was investigated at constant temperatures of 12, 15, 18, 21, 24, 27, 30, 32, and 34°C. The range in pupal duration was 7-61 d for H. tarandi, and 7.6-43.5 d for C. trompe. C. trompe developed significantly faster than H. tarandi, and males in both species eclosed 1-4 d before females. Rate of development as a function of temperature was described with a nonlinear, 3-parameter model. Flies also were reared in the field in 1990, 1991, and 1992, and microtemperatures within puparia were logged to be applied in the model obtained at constant temperatures. The predicted eclosion dates were close to the median observed dates. The daily rate of development was then regressed on standard macrometeorological records (predictors used were daily mean and maximum temperatures, Julian day, and cloud cover) in a multiple linear regression (r2 ≈0.80). This model was used to predict eclosion for 14 selected summers (1972-1993) at 1 meteorological station (Suolovuopmi), and at 8 different stations in northern Norway in 1992. Difference in eclosion dates among years ranged up to 40 d, and in cold summers eclosion takes place so late that few eggs or larvae are likely to be transmitted to the host, Rangifer tarandus (L.). Summer climate is hypothesized to be responsible for differences observed among years in larval infestation levels."
"57197485867;7006504263;35418273600;7201788967;","Energy, volatile production, and climatic effects of the Chicxulub Cretaceous/Tertiary impact",1997,"10.1029/97JE01743","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031586366&doi=10.1029%2f97JE01743&partnerID=40&md5=9b7b48f675b06f9d0d54eec1ba58e7a5","A comprehensive analysis of volatiles in the Chicxulub impact strongly supports the hypothesis that impact-generated sulfate aerosols caused over a decade of global cooling, acid rain, and disruption of ocean circulation, which contributed to the mass extinction at the Cretaceous/Tertiary (K/T) boundary. The crater size, meteoritic content of the K/T boundary clay, and impact models indicate that the Chicxulub crater was formed by a short period comet or an asteroid impact that released 0.7-3.4 × 1031 ergs of energy. Impact models and experiments combined with estimates of volatiles in the projectile and target rocks predict that over 200 gigatons (Gt) each of SO2 and water vapor, and over 500 Gt of CO2, were globally distributed in the stratosphere by the impact. Additional volatiles may have been produced on a global or regional scale that formed sulfate aerosols rapidly in cooler parts of the vapor plume, causing an early, intense pulse of sulfuric acid rain. Estimates of the conversion rate of stratospheric SO2 and water vapor to sulfate aerosol, based on volcanic production of sulfate aerosols, coupled with calculations of diffusion, coagulation, and sedimentation, demonstrate that the 200 Gt stratospheric SO2 and water vapor reservoir would produce sulfate aerosols for 12 years. These sulfate aerosols caused a second pulse of acid rain that was global. Radiative transfer modeling of the aerosol clouds demonstrates (1) that if the initial rapid pulse of sulfate aerosols was global, photosynthesis may have been shut down for 6 months and (2) that for the second prolonged aerosol cloud, solar transmission dropped 80% by the end of first year and remained 50% below normal for 9 years. As a result, global average surface temperatures probably dropped between 5° and 31°K, suggesting that global near-freezing conditions may have been reached. Impact-generated CO2 caused less than 1°K greenhouse warming and therefore was insignificant compared to the sulfate cooling. The magnitude of sulfate cooling depends largely upon the rate of ocean mixing as surface waters cool, sink, and are replaced by upwelling of deep ocean water. This upwelling apparently drastically altered ocean stratification and circulation, which may explain the global collapse of the delta 13C gradient between surface and deep ocean waters at the K/T boundary. Copyright 1997 by the American Geophysical Union."
"7003487440;35588263000;","Characteristics of aeolian grain transport over a fluvio-glacial lacustrine braid delta, lake Tekapo, New Zealand",1997,"10.1002/(SICI)1096-9837(199708)22:8<773::AID-ESP781>3.0.CO;2-O","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030810357&doi=10.1002%2f%28SICI%291096-9837%28199708%2922%3a8%3c773%3a%3aAID-ESP781%3e3.0.CO%3b2-O&partnerID=40&md5=57f18ccbe824773e3747e3ac7ff9ba9f","This paper presents results from one of the few scientific studies to examine the physical characteristics of aeolian sediment transport in an alpine area, where topographically reinforced winds initiate dust storm events. The major objective of this study is to improve knowledge of aeolian processes in mid-latitude alpine regions experiencing extreme wind speeds. Of particular interest is the role of surface characteristics in contributing to the unusually deep saltation layer which is seen to form over fluvio-glacial deposits in the Southern Alps of New Zealand, Sediment was collected at several heights (0.5, 1, 2 and 4m) and locations over a large alpine braided river delta, and standard laboratory techniques used to examine grain size characteristics. An image processing technique was also used to evaluate gram roundness. Grains filtered from the airstream at 0.5 m and 1m above such surfaces were found to display a mean grain size of approximately 300 to 435μm. resembling grain size characteristics of saltation clouds previously observed in high latitude, cold climate locations, in contrast to desert and praine environments. Samples collected at 2 and 4 m above the surface were found to consist of 60 to 65 per cent sand-sized material, with some grains exceeding 1-1.5 mm in diameter. Grain shape analysis conducted on silt- and clay-sized grains filtered from the airstream above mixed sand and gravel surfaces showed such grains to display an increase in grain roundness with height. This characteristic is thought to reflect the airstream's shape-sorting ability and has important implications with respect to the often observed increase in grain roundness in aeolian deposits with increasing distance from source areas. Namely, if more rounded grains are preferentially carried higher into the airstream and therefore into regions of higher wind speed, they should theoretically be transported further from the entrainmem zone before being deposited. The high wind speeds observed, often exceeding 30ms-1, arc seen to transport significantly larger sediment than reported in the literature for desert and prairie environments. In addition, the mixture of grain sizes, and especially the pebble- and cobblc-sized clasts that dominate the fluvio-glacial deposits associated with the braided rivers in this mountain region, also appear to increase significantly the trajectory height of saltating sand grains. As a result of these two factors, the depth of the saltation cloud often exceeds 1m. Observations made in this study therefore highlight the need for field and laboratory aeolian process studies to be extended to examine grain transport over coarse-grained beds during much higher wind velocities than typically reported in the literature. Such studies would provide a valuable insight into aeolian processes in high latitude/altitude environments, such as loess genesis. © 1997 by John Wiley &amp; Sons, Ltd."
"7003278104;6504600080;","Removing satellite equatorial crossing time biases from the OLR and HRC datasets",1997,"10.1175/1520-0442(1997)010<2125:RSECTB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-5844386438&doi=10.1175%2f1520-0442%281997%29010%3c2125%3aRSECTB%3e2.0.CO%3b2&partnerID=40&md5=784f4fc0088f5682aff9077e42b6c929","The objective of this study is to examine the impacts from satellite equatorial crossing time (ECT) changes on the outgoing longwave radiation (OLR) and highly reflective cloud (HRC) datasets and to design appropriate and robust methods to remove these satellite-dependent biases. The OLR record covers the period from June 1974 to July 1996 and is on a 2.5° grid extending from 30°S to 30°N over the global Tropics. The HRC record covers the period from January 1971 to December 1987 and is on a 2° grid extending from 25°S to 25°N over the global Tropics. Rotated empirical orthogonal function analysis (REOF) is performed on both the monthly OLR and HRC anomalies to help distinguish between artificial modes of variability and those associated with real variability. Results from the analysis show that significant errors are introduced by changes in the satellite ECT, and they appear differently in the two datasets. The primary satellite-related bias in the OLR appears as the fourth REOF mode, which accounts for 4.4% of the OLR anomaly variance. Its spatial pattern exhibits a strong surface signature over land, with the opposite sign over many of the deep convective regions of the ocean. During some periods, these biases result in widespread errors of over 10 W m-2, which are sustained for several months to over a year. In other cases, the transition between satellites induces abrupt, artificial changes in the OLR as high as 16 W m-2. In the HRC, the satellite-related bias appears as the leading two REOF modes, which account for 13.1% of the HRC anomaly variance. The spatial patterns of the HRC biases are indicative of an overall change in the mean climatological convection pattern. The above results can be understood by considering the sampling and radiometric characteristics of the OLR and HRC datasets. To remove the satellite ECT biases, the REOF time series of the satellite-related modes are modified by using the detailed knowledge of the satellite ECTs so that only artificial variability related to the satellite changes is captured and the natural variability is excluded. These modified time series are used in conjunction with their associated spatial patterns to compute the satellite-related artificial variability, which is then removed from the two datasets. These datasets provide an improved resource to study intraseasonal and longer timescale regional climate variations, large-scale interannual variability, and global-scale climate trends. Analyses of the long-term trends in both datasets show that the satellite biases induce artificial trends in the data and that these artificial trends are reduced in the corrected datasets. Further, each of the corrected datasets exhibits a trend in the tropical western-central Pacific that appears spatially independent of the satellite biases and agrees with results of previous studies that indicate an increase in precipitation has occurred in this region over the period encompassed by these datasets."
"7406372329;","Air-sea interactions of relevance to the ITCZ: Analysis of coupled instabilities and experiments in a hybrid coupled GCM",1997,"10.1175/1520-0469(1997)054<0134:ASIORT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-5244372231&doi=10.1175%2f1520-0469%281997%29054%3c0134%3aASIORT%3e2.0.CO%3b2&partnerID=40&md5=c798a3f7d22f22412c90dde393a99222","The eastern Pacific and Atlantic have a curious climatic asymmetry relative to the equator. Whereas the intertropical convergence zone (ITCZ) characterized by persistent and heavy rainfall and the warmest surface waters reside north of the equator, a cold tongue in sea surface temperature (SST) occurs at and south of the equator even though the time-mean solar radiation is approximately symmetric about the equator. In this paper the author investigates the relative role of three types of coupled ocean-atmosphere interaction processes - the meridional wind-SST feedback, the evaporation-wind feedback, and the low-level stratus cloud-SST feedback - in determining the climatic asymmetry relative to the equator. This study has two components. First, a simple analytical model is constructed in which the aforementioned three positive-feedback mechanisms are all included in a unified dynamic framework. The author's stability analysis indicates that in a reasonable parameter regime the growth rates associated with the three coupled instabilities are of the same order of magnitude, suggesting that they are all important in contributing to the climatic asymmetry. Because of the dependence of the three feedback mechanisms on the existence of a shallow oceanic mixed layer that, in turn, is a result of equatorial easterlies, the existence of the equatorial easterlies is essential for the amplification of the climatic asymmetry. Next, a hybrid coupled general circulation model is used in which a realistic continental and coastal geometry is presented. The model starts from an ideal symmetric condition forced only by the annual-mean insolation at the top of the atmosphere which is approximately symmetric about the equator. In the presence of the three airsea interaction mechanisms, the coupled model is capable of reproducing a realistic asymmetric time-mean state in the eastern Pacific and Atlantic. The fundamental cause of the asymmetry in the eastern Pacific is the tilt of the western coast of the Americas, which perturbs SST in the vicinity of the coastal region through a so-called coastal wind-upwelling mechanism. The asymmetry in the Atlantic, on the other hand, results from the land-ocean thermal contrast between the bulge of northwestern Africa and the ocean to the south. The oceanatmosphere interactions act as an amplifier to amplify the asymmetry set up by the continental or coastal asymmetry. Numerical experiments presented here demonstrate the importance of the geographic asymmetries and the ocean-atmosphere interactions in determining the preferred climatic position for the ITCZ."
"7103365606;26643566500;6505843428;6603064464;7202726814;","A synoptic evaluation of the NCEP ensemble",1997,"10.1175/1520-0434(1997)012<0140:ASEOTN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031452979&doi=10.1175%2f1520-0434%281997%29012%3c0140%3aASEOTN%3e2.0.CO%3b2&partnerID=40&md5=026496d1d80ca29db8277c487b79f747","Ensemble forecasting has been operational at NCEP (formerly the National Meteorological Center) since December 1992. In March 1994, more ensemble forecast members were added. In the new configuration, 17 forecasts with the NCEP global model are run every day, out to 16-day lead time. Beyond the 3 control forecasts (a T126 and a T62 resolution control at 0000 UTC and a T126 control at 1200 UTC), 14 perturbed forecasts are made at the reduced T62 resolution. Global products from the ensemble forecasts are available from NCEP via anonymous FTP. The initial perturbation vectors are derived from seven independent breeding cycles, where the fast-growing nonlinear perturbations grow freely, apart from the periodic rescaling that keeps their magnitude compatible with the estimated uncertainty within the control analysis. The breeding process is an integral part of the extended-range forecasts, and the generation of the initial perturbations for the ensemble is done at no computational cost beyond that of running the forecasts. A number of graphical forecast products derived from the ensemble are available to the users, including forecasters at the Hydrometeorological Prediction Center and the Climate Prediction Center of NCEP. The products include the ensemble and cluster means, standard deviations, and probabilities of different events. One of the most widely used products is the ""spaghetti"" diagram where a single map contains all 17 ensemble forecasts, as depicted by a selected contour level of a field, for example, 5520 m at 500-hPa height or 50 m s-1 windspeed at the jet level. With the aid of the above graphical displays and also by objective verification, the authors have established that the ensemble can provide valuable information for both the short and extended range. In particular, the ensemble can indicate potential problems with the high-resolution control that occurs on rare occasions in the short range. Most of the time, the ""cloud"" of the ensemble encompasses the verification, thus providing a set of alternate possible scenarios beyond that of the control. Moreover, the ensemble provides a more consistent outlook for the future. While consecutive control forecasts verifying on a particular date may often display large ""jumps"" from one day to the next, the ensemble changes much less, and its envelope of solutions typically remains unchanged. In addition, the ensemble extends the practical limit of weather forecasting by about a day. For example, significant new weather systems (blocking, extratropical cyclones, etc.) are usually detected by some ensemble members a day earlier than by the high-resolution control. Similarly, the ensemble mean improves forecast skill by a day or more in the medium to extended range, with respect to the skill of the control. The ensemble is also useful in pointing out areas and times where the spread within the ensemble is high and consequently low skill can be expected and, conversely, those cases in which forecasters can make a confident extended-range forecast because the low ensemble spread indicates high predictability. Another possible application of the ensemble is identifying potential model errors. A case of low ensemble spread with all forecasts verifying poorly may be an indication of model bias. The advantage of the ensemble approach is that it can potentially indicate a systematic bias even for a single case, while studies using only a control forecast need to average many cases."
"6603139355;57201124395;7004494327;6701843835;","The water-soluble fraction of atmospheric aerosol particles and its influence on cloud microphysics",1996,"10.1029/96jd02245","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030357929&doi=10.1029%2f96jd02245&partnerID=40&md5=c873487d54aafd4040f91e4a2b5233e1","The water-soluble fraction of atmospheric aerosol particles is a major property dividing the particle population into cloud condensation nuclei and interstitial particles during cloud formation. Likewise, this property influences cloud microphysics and chemistry as well as direct and indirect aerosol forcing of climate. Up to now this important parameter has been only poorly determined experimentally. Here, we present SoFA, a new method to determine the water-Soluble Fraction of large and giant Aerosol particles in five narrow size bands with geometrical radii of 0.4, 0.6, 0.9, 1.3, 1.8 μm and one band for particles with radius larger than 2.3 μm. First results show three different types of aerosol particles (AP I, II, III). AP I were characterized by 9% water-soluble material, and AP II by 50% and correspond to those found in earlier studies for small particles. The new AP III consists of 88% water-soluble material. In those size bands, where all three particle types could be detected (0.9, 1.3, and 1.8 μm; because of detection limits of SoFA, only two types of particles could be detected in the remaining size bands), about 50% of the total number of analyzed particles belong to APIII, whereas about 25% belong to both AP II and I. These numbers lead to 59% water-soluble material on average. Particles of AP III are assumed to be cloud-processed particles, those of AP I might be of biological origin. The impact of the water-soluble fraction of particles on cloud microphysics is investigated by comparing two cloud situations using an entraining air parcel model with detailed microphysics. The model simulations show an influence on nucleation scavenging, cloud interstitial aerosol, and in particular, drop size population. Most notable is that the same aerosol particle number distribution causes either a precipitating or a non precipitating cloud, depending only upon different water-soluble fractions of the particles."
"7003904922;","Correlations of atmospheric dynamics with solar wind-induced changes of air-earth current density into cloud tops",1996,"10.1029/96jd01990","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041661098&doi=10.1029%2f96jd01990&partnerID=40&md5=ca40376e148d1dbdb8ae617692505559","We analyze reported correlations between solar activity and weather and climate and show that in six independent data sets there is a correlation of measured changes in atmospheric dynamics with measured or inferred changes in vertical atmospheric air-earth current density. The current density changes are due to external modulation of the global electric circuit by the solar wind. We describe the several ways in which the solar wind modulates the global circuit, and the observations that support a simple model of the circuit, with two return paths in parallel. One return path is at low latitudes with relatively constant impedance and the other is at high latitudes and is responsive to solar wind modulation. The six independent data sets exhibiting the correlations include meteorological and air-earth current density changes on the 10 to 12-year solar cycle as well as on the day-to-day timescales of Forbush decreases of galactic cosmic ray flux and of hcliospheric current sheet crossings. The geographic locations include northern and southern high latitudes as well as the tropics. In regions where these correlations are found, there exists free energy in the form of supercooled water droplets near the tops of clouds that are unstable with respect to precipitation. Laboratory data and models suggest that electrostatic charge accumulating on supercooled droplets and aerosols near cloud tops affects the probability of ice nucleation and droplet freezing, enhancing the rate of growth and sedimentation of ice crystals. This proposed mechanism is also an explanation for another longstanding meteorological problem, the discrepancy between measurements at cloud tops of initial concentrations of ice and of concentrations of ice-forming nuclei. For light cloud cover the effect of increases in ice nucleation and sedimentation can be to reduce cloud opacity and albedo. For storm cloud systems the effect can be to enhance precipitation rates and latent heat release intensifying the storm. In several cases, measured or inferred storm intensification (or weakening) is directly related to measured or inferred increases (or decreases) of air-earth current density. Thus electrical effects on cloud microphysics may serve as connecting links between the observed or inferred increases in air-earth current density and the observed changes in atmospheric dynamics. In cases where thunderstorm electric fields arc generated there are additional cloud microphysical effects that might contribute to the correlations. We discuss the present uncertainties regarding solar wind effects on the distribution of air-earth current density in the global electric circuit and regarding the relevant cloud microphysics. Much work is required to quantify these effects and evaluate their importance relative to competing processes."
"7006550762;7005117153;7402959242;","Climatic effect of water vapor release in the upper troposphere",1996,"10.1029/96jd02747","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030367865&doi=10.1029%2f96jd02747&partnerID=40&md5=d645350aa4921c1e8e7316b92fbe5df5","Water vapor is released into the Goddard Institute for Space Studies (GISS) global climate middle atmosphere model at the locations and cruise altitude of subsonic aircraft. A range of water vapor values is used to simulate not only current and 2015 projected emissions but also to provide larger signal-noise ratios. The results show that aircraft water vapor emissions do not significantly affect the model's climate, either at the surface or in situ. With emissions some 15 times higher than the 2015 projection, a small impact is observed, amounting to a few tenths degrees Celsius globally and locally, while with emissions 300 times the 2015 values, a global warming of 1°C results. However, with releases this large, only about 5% actually stays in the atmosphere. The larger emissions increase the specific humidity most in the tropical lower troposphere, partly as a result of increased evaporation due to the global warming; at flight altitudes, relative humidity and cloud cover increase at latitudes of emission, and temperature decreases. Surface warming is relatively independent of latitude, and only a slight longitudinal aircraft footprint is found in the warming for the most extreme experiment. Comparison to increased CO2 experiments of similar magnitude warming shows that the upper tropospheric response is greater in the water vapor release experiments, but the high-latitude surface temperature response is larger with increased CO2 due to more effective cryospheric feedbacks."
"7003430284;6701757453;7007108728;7006417954;25629339800;56000281400;57205351494;26643510900;7005862399;7101973428;","Physical and chemical observations in marine stratus during the 1993 North Atlantic Regional Experiment: Factors controlling cloud droplet number concentrations",1996,"10.1029/96jd01228","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030434120&doi=10.1029%2f96jd01228&partnerID=40&md5=2ee45a08f7f1b730cf74a7803e2bde7a","Airborne observations from 14 flights in marine stratus over the Gulf of Maine and Bay of Fundy in August and September of 1993 are examined for the relationships among the cloud droplet number concentrations (Nd), the out-of-cloud aerosol particle number concentrations (Na), the major ion concentrations in the cloud water, and turbulence in cloud. There was a wide range of aerosol concentrations, but when low stratus and the main anthropogenic plume from eastern North America were in the same area the plume overrode the cloud. The Nd increased with increasing Na and cloud water sulfate concentration (cwSO4=), but the relationships were very weak. The separation of the data between smooth and lightly turbulent air substantially improved the ability to explain the variance in the Nd by either of these two quantities. Also, the relative increase in Nd for increases in Na and cwSO4= was greater for lightly turbulent air than for smooth air. The estimated minimum size of particles activated in these clouds ranged from 0.14 μm to 0.31 μm, corresponding to average supersaturations of &lt;0.1%. The minimum size tended to be lower for lightly turbulent air and smaller Na. The results for lightly turbulent air agree well with previously reported parameterizations of the impact of aerosols on Nd, but the results for smooth air do not agree. In general, more knowledge of the physical factors controlling the Nd in stratiform clouds, such as turbulence, is needed to improve not only our ability to represent Nd but also to increase our understanding of the impact of the aerosol particles on the Nd and climate."
"7402959242;7006550762;7005117153;","Could high-speed civil transport aircraft impact stratospheric and tropospheric temperatures measured by microwave sounding unit?",1996,"10.1029/96jd02721","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0342995570&doi=10.1029%2f96jd02721&partnerID=40&md5=33bca94dc71abfdc4d31987cc19c2511","A radiative transfer postprocessor calculates microwave brightness temperatures Tb from climate experiments investigating supersonic aircraft exhaust impacts with the Global Climate/Middle Atmosphere Model (GCMAM) at the NASA Goddard Institute for Space Studies. Microwave signals from the exhaust-perturbed GCMAM atmospheres are contrasted with observed interannual variability (natural ""noise"") for 1982-1991 as measured by microwave sounding unit (MSU) channels across the lower troposphere, midtroposphere, and lower stratosphere. Exaggerated ozone and water vapor perturbations at supersonic cruise altitudes produce microwave signals easily detected against natural noise. Removal of ozone greenhouse action between 200 and 50 hPa cools all MSU channels with greatest ΔTb of -8.3 K and signal-to-observed-noise (S/N) ratios above 20 in the lower stratospheric channel. Doubling middle-atmospheric water vapor above 100 hPa cools lower stratospheric Tb values by 1.5 K while warming tropospheric channels, particularly the tropopause channel. Detectable S/N ratios of 2-4 occur over the tropics and subtropics in the lower-to-middle troposphere and lower stratosphere. Realistic ozone and water vapor perturbations are based on the High-Speed Research Program/Atmospheric Effects of Stratospheric Aircraft reports. These realistic stratospheric ozone and water vapor changes produce ΔTb signals under 0.6 K and negligible S/N ratios. The slight climatic forcings are overwhelmed by natural feedbacks of high and low cloud formation, sea ice formation, and snow coverage. Thus the modeled realistic ozone and water vapor perturbations produce small and conflicting microwave signals, undetectable against natural variability and other sources of anthropogenic climatic forcing."
"57193882808;57203012011;7006095466;","Cloud-resolving modeling of tropical cloud systems during phase III of GATE. Part I: Two-dimensional experiments",1996,"10.1175/1520-0469(1996)053<3684:CRMOTC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030326509&doi=10.1175%2f1520-0469%281996%29053%3c3684%3aCRMOTC%3e2.0.CO%3b2&partnerID=40&md5=05d4a56c2d04d3a17c0edaf70d7ee602","A formal framework is established for the way in which cloud-resolving numerical models are used to investigate the role of precipitating cloud systems in climate and weather forecasting models. Emphasis is on models with periodic lateral boundary conditions that eliminate unrealistic numerically generated circulations caused by open boundary conditions in long-term simulations. Defined in this formalism is the concept of large-scale forcing and the cloud-environment interactions that are consistent with the periodic boundary conditions. Two-dimensional numerical simulations of the evolution of cloud systems during 1-7 September 1974 in Phase III of the Global Atmospheric Research Program Atlantic Tropical Experiment (GATE) are conducted. Based on the above formalism, a simple technique is used to force an anelastic cloud-resolving model with evolving large-scale horizontal wind field and large-scale forcing for the temperature and moisture obtained from the GATE data. The 7-day period selected is characterized by transitions of the cloud systems through several regimes, in response to evolving large-scale forcing and vertical wind shear as an easterly wave passes over the region. The observed nonsquall cloud clusters, squall lines (squall clusters), and scattered convection are all simulated. Model-produced budgets of heat and moisture compare well with GATE observations. It is argued that differences between simulations and observations (most apparent in the relative humidity) result from the treatment of condensed water. In particular, the lack of observed fields to prescribe forcing for the upper-tropospheric ice, together with the periodic lateral boundary conditions, results in a middle and upper troposphere that is too moist by 10%-20%. A key conclusion is that tropical convection, forced in a simple way by large-scale analysis, is sorted into specific regimes as a result of dynamic control by the wind shear. The quantification of this large-scale control is fundamental to the concept of convective parameterization. Furthermore, the cloud-resolving model results by design satisfy the large-scale budgets and, therefore, can be applied directly to the strategic problem of convective parameterization in weather forecasting and climate models."
"7006061457;6602135743;7004682291;","Vertical distribution of water content and optical characteristics of continental stratiform clouds",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030318577&partnerID=40&md5=0a61516643ebb377c4b46d91ba6767bf","The archives of aircraft microphysical cloud measurements at the Cloud Physics Laboratory of the Central Aerological Observatory (CAO) contain huge amounts of observational data. The generalized data on cloud water content W and visible light extinction coefficient ε make it possible to get an idea about their characteristic values in stratiform clouds and vertical distribution. To use the obtained empirical relations in climate models and in solution of other practical problems, simple parametrizations of the vertical distribution of relative water content, visible light extinction coefficient, and effective particle radius in strati-form clouds are suggested as well as the dependences of the mean cloud water path P and optical cloud depth τ and also of the effective particle radius re.cl on cloud thickness. A notion is introduced of an equivalent liquid cloud (ELC) whose parameters are calculated from measured W and ε. The knowledge of cloud microphysics allows us to judge about some optical parameters of actual clouds irrespective of their phase structure."
"35461255500;7006712143;7004296083;7005755464;56264677300;26643041500;57193897609;24311471900;7004713188;57216677408;","Formation, growth, and properties of atmospheric aerosol particles and cloud droplets",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030358044&partnerID=40&md5=ca4b94ef0b11722d7377a88d96b681b5","Formation and growth of atmospheric aerosol particles and their physico-chemical properties have been examined using both aerosol and cloud models, and by conducting field experiments in the Finnish Arctic. Several routes for atmospheric particle production via homogeneous nucleation are proposed Sulphuric acid - water nucleation is studied in more detail, and occasions of new particle production in the Finnish Arctic are identified. The bulk aerosol in the Finnish Arctic is rather acidic with the least acidic particles originating from the ocean, and the most acidic ones from the East. We are able to show that the nucleation characteristics of these two types of particles are different. Acidic vapors are in addition shown to contribute to the formation and growth of cloud droplets strongly enough to change the optical thickness of an idividual cloud under certain conditions."
"7005228425;7005174340;","On the sensitivity of cloud albedo to the partitioning of participate absorbers in cloudy air",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030406360&partnerID=40&md5=d92b3a2a1fea962310933d6fc6768d0f","This study concerns the radiative effect of anthropogenic aerosols on the optical properties of stratiform boundary-layer clouds. Specifically, we analysed the influence of the partitioning of aerosol absorbers between interstitial air and cloud drops and the effect of different internal distributions of this absorber in the drops on cloud albedo. These effects were investigated with a radiative transfer model. Instead of the highly unrealistic size-independent volume ratios of absorbers in earlier studies, constant-size absorber in each drop (corresponding to a monodisperse absorber size distribution) with realistic total amounts caused significant albedo reductions for the modelled clouds. Atmospheric dilution and deposition will decrease aerosol concentrations with increasing distance from the pollution sources. The model calculations showed that the ensuing reduction in anthropogenic albedo change can be compensated by an expected concurrent change in absorber partitioning in the clouds. Thus, the aera of significant (2 to 5%) reduction of cloud albedo will be extended on the order of a thousand kilometres about the centres of anthropogenic combustion sources."
"7101899854;7004899626;35468686100;7202899330;","Spectral reflectance and atmospheric energetics in cirrus-like clouds. Part II: Applications of a Fourier-Riccati approach to radiative transfer",1996,"10.1175/1520-0469(1996)053<3450:SRAAEI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030324088&doi=10.1175%2f1520-0469%281996%29053%3c3450%3aSRAAEI%3e2.0.CO%3b2&partnerID=40&md5=6e107206ae2ce41e50d5539862b28dfe","One of the major sources of uncertainty in climate studies is the detection of cirrus clouds and characterization of their radiative properties. Combinations of water vapor absorption channels (e.g., 1.38 μm), ice-water absorption channels (e.g., 1.64 μm), and atmospheric window channels (e.g., 11 μm) in the imager, together with a lidar profiler on future EOS platforms, will contribute to enhancing our understanding of cirrus clouds. The aforementioned spectral channels are used in this study to explore the effects exerted by uncertainties in cloud microphysical properties (e.g., particle size distribution) and cloud morphology on the apparent radiative properties, such as spectral reflectance and heating and cooling rate profiles. As in Part I of our previous study, which establishes the foundations of the Fourier-Riccati method of radiative transfer in inhomogeneous media, cloud extinction and scattering functions are characterized by simple spatial variations with measured and hypothesized microphysics to facilitate our understanding of their radiative properties. Results of this study suggest that (i) while microphysical variations in the scattering and extinction functions of clouds affect the magnitudes of their spectral reflectances, cloud morphology significantly alters the shape of their angular distribution; (ii) spectral reflectances viewed near nadir are least affected by cloud variability; and (iii) cloud morphology can lead to spectral heating and cooling rate profiles that differ substantially from their plane-parallel averaged equivalents. Since there are no horizontal thermal gradients in plane-parallel clouds, it may be difficult to correct for this deficiency."
"7006232011;57197124027;","Monitoring and modelling of the radiation climate at Abisko",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030472904&partnerID=40&md5=82625add58de205e31445313c3bb7bc5","Photosynthetically active radiation (PAR), ultraviolet-B (UV-B) radiation and sun-minutes per hour have been monitored at Abisko Scientific Research Station in northern Sweden during the summer of 1994. The PAR and UV-B values have been compared to models, and from the comparison cloud transmission fractors could be detemrined and compared for the two wavebands. For the whole period the clouds, on average, decreased the UV-B to 74.2% of what it would have been without clouds. This means that in simultaneous experiments in which vegetation was irradiated with extra UV-B corresponding to 15% depletion under clear skies, taking cloud cover into account, the radiation corresponds to 19.0% ozone depletion. Ozone column at Abisko during the summer 1994 estimated from measurements at Vindeln to the south of Abisko and Tromso to the north showed no depletion compared to a model based on values determined 3-4 decades earlier."
"7005228425;35592560600;7006307463;7003784762;","Climate forcing and the physico-chemical life cycle of the atmospheric aerosol - Why do we need an integrated, interdisciplinary global research programme?",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030472903&partnerID=40&md5=faf24a79bc9b4e884465664f62e0f29d","In the past, different branches of the atmospheric sciences separately conducted research concerning the role of the atmospheric aerosol in cloud physics, atmospheric chemistry and radiative transfer. Findings of the last few years have emphasised the importance of the atmospheric aerosol for both climate change and the cycles of atmospheric trace substances. In this peer- reviewed editorial, arguments are given for research needed in order to include the atmospheric aerosol as a prognostic variable in global models of climate and trace substances. A program for the necessary integrated, interdisciplinary aerosol research is formulated, combining in-situ physical and chemical aerosol characterisation, remote sensing and modelling. It is necessary to emphasise the need for integration of the key activities, which individually, by themselves, cannot yield an adequate basis for a full characterisation of the climate effect of aerosols or of changes in atmospheric composition."
"6602823628;6506456205;","Empirical orthogonal function approximation of mean monthly precipitation over North Africa",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030320052&partnerID=40&md5=1087c2ca835c94d4fe23f12b232dc7a5","The results of the approximation of mean monthly precipitation fields over North Africa and the Sudan/Sahel region by series of empirical orthogonal functions (EOF) for all months of the year are considered. It is found that in monsoon months the contribution of subsynoptic-scale processes to the formation of the precipitation regime may exceed 73% of the sample variance over the Sudan/Sahel region and 68% over North Africa. This indicates that in hydrodynamic prognostic and climate models that cover tropical latitudes, it is necessary not only, to describe properly synoptic-scale. processes (monsoon. convective clouds and the precipitation processes in them), but it is more important to make the accurate parametrization of subgrid mesoscale processes."
"7102015136;6602112847;6602132019;7003740015;","Dimethylsulfide oxidation and the ratio of methanesulfonate to non sea-salt sulfate in the marine aerosol",1996,"10.1007/BF00053798","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030302503&doi=10.1007%2fBF00053798&partnerID=40&md5=30fbf17e3dcb001dc0bf3cf49316a154","A box model of DMS oxidation in the clean, low-NO(x) marine atmospheric boundary layer has been used to predict the latitude dependence of the aerosol methanesulfonate to non sea-salt sulfate ratio. The observed latitude dependence of this ratio in the Southern Hemisphere can be reproduced reasonably well if the full suite of reactions proposed by Yin et al. is employed, and a strong temperature dependence is specified in the rates of decomposition of CH3SO2 and CH3SO3 radicals."
"6603831835;","Aladin on ISS for numerical weather prediction and climate",1996,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-5244244053&partnerID=40&md5=35a5a9f3aeb7f097e275f9487cd7124d","Earlier in this session of the symposium the importance of wind information to operational meteorology was stressed by Steven Tjemkes, and Jean-Noel Thépaut presented a preliminary assessment of the large potential benefit of global wind profile measurements for Numerical Weather Prediction. In this paper the further benefits of such data for climate studies will be summarised. A Doppler Wind Lidar instrument as considered in the Earth Explorer Atmospherics Dynamics Mission assessment report would be able to provide vertical wind profile information in clear air and above thick cloud. The review of nine Earth Explorer Missions by the European user community and two peer review groups, was recently finalised by the ESA Science Advisory Committee. The Atmospheric Dynamics Mission was considered unique and well-feasible and rated of second priority amongst the nine. It was recommended for phase A study together with three other missions. Mike Reynolds presented programmatic and technical advantages for the implementation of a Doppler Wind Lidar instrument on the ISS, rather than on a free-flyer satellite in a dawn-dusk polar orbit. In this paper a scientific assessment will be given of the pros and cons of an ISS rather than a free-flyer implementation. In particular, aspects of data quality, coverage, (real-time) availability, and continuity are addressed. It is concluded that on some of these aspects a full answer can not be given at this moment. However, an implementation on the ISS seems at this stage well feasible and scientifically balanced against a Doppler Wind Lidar demonstration on a free-flyer."
"6603216492;15848579900;15081276400;26541455200;35277802900;7005171140;7004389152;9133595500;8144447800;7201778786;6507179561;6507770401;","Remote Sensing Data Acquisition, Platforms and Sensor Requirements",1996,"10.1007/BF03026230","https://www.scopus.com/inward/record.uri?eid=2-s2.0-10844255397&doi=10.1007%2fBF03026230&partnerID=40&md5=726b5fb3af5d544b60614459b97f4249","Although data available from various earth observation systems have been routinely used in many resource applications, however there have been gaps, and data needs of applications at different levels of details have not been met. There is a growing demand for availability of data at higher repetivity, at higher spatial resolution, in more and narrower spectral bands etc. Some of the thrust areas of applications particularly in the Indian context are; - Management of natural resources to ensure sustainable increase in agricultural production, - Study the state of the environment, its monitoring and assessment of the impact of. various development actions on the environment, - Updating and generation of large scale topographical maps. - Exploration/exploitation of marine and mineral resources and - Operational meteorology and studying various land and oceanic processes to understand/predict global climate changes. Each of these thrust area of application has many components, related to basic resource areas such as agriculture, forestry, water resources, minerals, marine resources etc. and the field of cartography. Observational requirements for major applications have been summarized as under. Monitoring vegetation health from space remains the most important observational parameter with applications, in agriculture, forestry, environment, hydrology etc. Vegetation extent, quantity and temporal changes are the three main requirements which are not fully realized with RS data available. Vegetation productivity, forest biomass, canopy moisture status, canopy biogeochemistry are some examples. Crop production forecasting is an important application area. Remotely sensed data has been used for identification of crops and their acreage estimation. Fragmented holdings, large spread in crop calendars and different management practices continue to pose a challenge lo remote sensing. Remotely sensed data at much higher spatial resolution than hitherto available as well as at greater repetivity are required to meet this need. Non-availability of cloud-free data in the kharif season is one of the serious problems in operational use of remote sensing for crop inventory. Synthetic aperture radar data al X & Ku bands is necessary to meet this demand. Nutrient stress/disease detection requires observations in narrow spectral bands. In case of forestry applications, multispectral data at high spatial resolution of the order of 5 to 10 metres is required to make working plans at forest compartment level. Observations from space for deriving tree height are required for volume estimation. Observations in the middle infrared region would greatly enhance capability of satellite remote sensing in forest fire detection. Temporal, spatial and spectral observational requirements in various applications on vegetation viewing are diverse, as they address processes at different spatial and time scales. Hence, it would be worthwhile to address this issue in three broad categories. a) Full coverage, moderate spatial resolution with high repetivity (drought, large scale deforestation, forest phenology....). b) Full coverage, moderate to high spatial resolution and high repetivity (crop forecasting, vegetation productivity). c) Selected viewing at high spatial resolution, moderate to high repetivity and with new dimensions to imaging (narrow spectral bands, different viewing angles). A host of agrometeorological parameters are needed to be measured from space for their effective use in development of yield models. Estimation of root-zone soil moisture is an important area requiring radar measurements from space. Surface meteorological observations from space at the desired spatial and temporal distributions has not developed because of heavy demands placed on the sensor as well as analytical operational models. Agrometeorology not only provides quantitative inputs to other applications such as crop forecasting, hydrological models but also could be used for farmer advisory services by local bodies. Mineral exploration requires information on geological structures, geomorphology and lithology. Surface manifestation over localized regions requires large scale mapping while the lithology can be deciphered from specific narrow bands in visible. NIR, MIR and TIR regions. Sensors identified for mapping/cartography in conjunction with imaging spectrometer would seem to cover requirements of this application. Narrow spectral bands in the short regions which provide diagnostics of relevant geological phenomenon are necessary for mineral exploration. Thermal inertia measurements help in better discrimination of different rock units. Measurements from synthetic aperture data which would provide information on geological structures and geomorphology are necessary for mineral exploration. The applications related to marine environment fall in three major areas: (i) Ocean colour and productivity, biological resources; (ii) Land-ocean interface, this includes coastal landforms, bathymetry, littoral transport processes, etc. and; (iii) Physical oceanography, sea surface temperature, winds, wave spectra, energy and mass exchange between atmosphere and ocean. Measurement of chlorophyll concentration accurately on daily basis, sea surface temperature with an accuracy of 0.5 °K. and information on current patterns arc required for developing better fishery forecast models. Improved spatial resolution data are desirable for studying sediment and other coastal processes. Cartography is another important application area. The major problems encountered in relation to topographic map updation are location and geometric accuracy and information content. Two most important requirements for such an application are high spatial resolution data of 1 to 2 metre and stereo capability to provide vertical resolution of 1 metre. This requirement places stringent demands on the sensor specifications, geometric processing, platform stability and automated digital cartography. The requirements for the future earth observation systems based on different application needs can be summarized as follows: • Moderate spatial resolution (l50-300m), high repetivity (2 Days), minimum set of spectral bands (VIS, NIR, MIR. TIR) full coverage. • Moderate to high spatial resolution (20-40m), high repetivity (4-6 Days), spectral bands (VIS, MR, MIR, TIR) full coverage. • High spatial resolution (5-10m) muitispectral data with provision for selecting specific narrow bands (VIS, N1R. MIR), viewing from different angles. • Synthetic aperture radar operating in at least two frequencies (C, X, Ku), two incidence angles/polarizations, moderate to high spatial resolution (20-40m), high repetivity (4-6 Days). • Very high spatial resolution (1-2m) data in panchromatic band to provide terrain details at cadastral level (1:10,000). • Stereo capability (1-2m height resolution) to help planning/execution of development plans. • Moderate resolution sensor operating in VIS, NIR, MIR on a geostationary platform for observations at different sun angles necessary for the development of canopy reflectance inversion models. • Diurnal (at least two i.e. pre-dawn and noon) temperature measurements of the earth surface. • Ocean colour monitor with daily coverage. • Multi-frequency microwave radiometer, scatterometer. altimeter, atmospheric sounder, etc. © 1996 Springer."
"7403282069;7202208382;","A semiempirical cloudiness parameterization for use in climate models",1996,"10.1175/1520-0469(1996)053<3084:ASCPFU>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030357842&doi=10.1175%2f1520-0469%281996%29053%3c3084%3aASCPFU%3e2.0.CO%3b2&partnerID=40&md5=36fc4b94be6216c691563dc3c6c7203a","Data produced from explicit simulations of observed tropical cloud systems and subtropical stratocumuli are used to develop a ""semiempirical"" cloudiness parameterization for use in climate models. The semiempirical cloudiness parameterization uses the large-scale average condensate (cloud water and cloud ice) mixing ratio as the primary predictor. The large-scale relative humidity and cumulus mass flux are also used in the parameterization as secondary predictors. The cloud amount is assumed to vary exponentially with the large-scale average condensate mixing ratio. The rate of variation is, however, a function of large-scale relative humidity and the intensity of convective circulations. The validity of such a semiempirical approach and its dependency on cloud regime and horizontal-averaging distance are explored with the simulated datasets."
"56269065000;55573647400;","The relative merit of cloud/clear identification in the NOAA/NASA Pathfinder AVHRR Land 10-day composites",1996,"10.1080/01431169608949149","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030282675&doi=10.1080%2f01431169608949149&partnerID=40&md5=cc11301277d713b488a903fb3efcec34","The Pathfinder Advanced Very High Resolution Radiometer (AVHRR) Land (PAL) dataset is a new generation of globally mapped long-term datasets produced from AVHRR onboard NOAA satellites. The PAL data, particularly their compressed version—the 10-day composites, are expected to be used quantitatively in climate applications/modelling and land cover/land cover change studies. There are, however, geographic areas that are not limited to tropics, where the 10-day composites are not cloud free. As a result, significant errors in the Normalized Difference Vegetation Index (NDVI), reflectances and brightness temperatures may occur. The PAL daily data processing included cloud/clear identification using the Clouds from AVHRR (CLAVR) procedure. The CLAVR flags were appended to each pixel but were not used for generating PAL 10-day data products. In this Letter, we use global PAL data for July 1988 to estimate quantitatively the effect of residual cloud contamination on PAL composite NDVI, reflectance, and brightness temperature data by comparing statistics of all composite pixels and of those identified by CLAVR as clear. We argue that post-composite cloud screening in PAL data is important and can be done using CLAVR flags. © 1996 Taylor & Francis Group, LLC."
"6701915334;6701832491;7202174228;7402504552;6602484498;6603645136;","Regional climate model of the Arctic atmosphere",1996,"10.1029/96jd02016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030410102&doi=10.1029%2f96jd02016&partnerID=40&md5=877bb4d9ede3a7d5f5d20dbecd775c63","A regional climate model of the whole Arctic using the dynamical package of the High-Resolution Limited Area Model (HIRLAM) and the physical parameterizations of the Hamburg General Circulation Model (ECHAM3) has been applied to simulate the climate of the Arctic north of 65 ° N at a 50-km horizontal resolution. The model has been forced by the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at the lateral boundaries and with climatological or actual observed sea surface temperatures and sea ice cover at the lower boundary. The results of simulating the Arctic climate of the troposphere and lower stratosphere for January 1991 and July 1990 have been described. In both months the model rather closely reproduces the observed monthly mean circulation. While the general spatial patterns of surface air temperature, mean sea level pressure, and geopotential are consistent with the ECMWF analyses, the model shows biases when the results are examined in detail. The largest biases appear during winter in the planetary boundary layer and at the surface. The underestimated vertical heat and humidity transport in the model indicates the necessity of improvements in the parameterizations of vertical transfer due to boundary layer processes. The tropospheric differences between model simulations and analyses decrease with increasing height. The temperature bias in the planetary boundary layer can be reduced by increasing the model sea ice thickness. The use of actual observed sea surface temperatures and sea ice cover leads only to small improvements of the model bias in comparison with climatological sea surface temperatures and sea ice cover. The validation of model computed geopotential, radiative fluxes, surface sensible and latent heat fluxes and clouds against selected station data shows deviations between model simulations and observations due to shortcomings of the model. This first validation indicates that improvements in the physical parameterization packages of radiation and in the description of sea ice thickness and sea ice fraction are necessary to reduce the model bias."
"7005729142;7004242319;","High albedos of cirrus in the tropical pacific warm pool: Microphysical interpretations from CEPEX and from Kwajalein, Marshall Islands",1996,"10.1175/1520-0469(1996)053<2424:HAOCIT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030431127&doi=10.1175%2f1520-0469%281996%29053%3c2424%3aHAOCIT%3e2.0.CO%3b2&partnerID=40&md5=1239686aefe7aff13a6f2ce7d6f56f44","Recent studies suggest that extensive shields of cirrus clouds over the equatorial Pacific ""warm pool"" may have a significant influence on the global climate, yet details of the links between cloud microphysical properties, upper-tropospheric latent and radiative heating rates, and climate are poorly understood. This study addresses whether relatively reflective ice crystals with dimensions smaller than about 100 μm near the tops of tropical cirrus clouds, produced by deep convection when the sea surface temperature exceeds 300 K, are principally responsible for the high albedos observed in this region. In situ measurements of ice crystal size distributions and shapes, acquired during the Central Equatorial Pacific Experiment (CEPEX), are used to derive cloud ice water content (IWC), particle cross-sectional area (A), and other microphysical and optical properties from particles with sizes down to 5 μm. These measurements are needed to ascertain the microphysical properties primarily responsible for determining cloud optical depth and albedo in visible wavelengths and were acquired by a Learjet flying in tropical cirrus and occasionally in convection between altitudes of 8 and 14 km (-20°C to -70°C). Previously unanalyzed microphysical measurements in the vicinity of Kwajalein, Marshall Islands, acquired in the mid-1970s from a WB57F aircraft between altitudes of 5 and 17 km, are also used to study the variation in microphysical properties from cirrus base to top, using a combination of constant-altitude penetrations and steep ascents and descents through cloud. Analysis shows that IWC, A, and various measures of particle size all tend to decrease with decreasing temperature and increasing altitude, although considerable scatter is observed. Small ice crystals make up more than half the mass and cause more than half the extinction on average in the upper, colder parts of the cirrus; however, the predominantly large particles in the lower, warmer parts of the cirrus contain at least an order of magnitude greater mass and are dominant in producing the high observed albedos. An examination of the lidar and radiometer data acquired onboard the NASA ER-2, which overflew the Learjet during CEPEX, supports the conclusion that the higher, colder regions of the cirrus typically have volume extinction coefficients that are only about 10% of those in the lower, warmer regions."
"6602521259;8204540500;35550805300;7005012025;","Sensitivity of a general circulation model to changes in northern hemisphere ice sheets",1996,"10.1029/96jd01219","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030428561&doi=10.1029%2f96jd01219&partnerID=40&md5=44984953617a9ae393f8458915601a03","Sensitivity experiments with a general circulation model demonstrate the role of ice sheet size on the local, regional, and global climate. Model experiments isolate the effects of albedo, height, and area of the ice sheets and show how the National Center for Atmospheric Research Community Climate Model 1 responds to changes in the size of northern hemisphere ice sheets. A flat ice sheet with full glacial areal extent but no elevation is used to study albedo effects. A full ice sheet with full glacial areal extent and elevation is used to represent height effects. An ice sheet with half the glacial area of the others but the full glacial elevation is used to represent area effects. All of the sensitivity experiments have (1) interactive sea surface temperatures calculated by a slab ocean and (2) modern boundary conditions except for the ice sheets. The experiments show that both the full and flat ice sheets lower the global mean surface temperatures (GMT) by 2.5°C and that the GMT is dependent upon the area, rather than the height, of the ice sheets. High ice sheets maintain colder temperatures than lower ice sheets over the ice sheets themselves, but compensating warmer temperatures occur downstream from the high ice sheets. The downstream warmer temperatures are the result of (1) glacial anticyclones that cause subsidence and reduced cloud cover during summer as well as reduced soil moisture and (2) increased southwesterly flow across the Atlantic Ocean that results in increased southerly advection of warm air during winter. A dynamical effect of the high ice sheets during summer is to change the wave number of the planetary waves in the midlatitudes, whereas a thermodynamic effect of the flat ice sheets during summer is to lower the geopotential heights throughout the northern hemisphere. In general, northern hemisphere ice sheets induce both a local response over the ice sheets and a regional response downstream from the ice sheets but have little impact on the southern hemisphere except where sea ice expands."
"35464731600;7005399437;","Hemispherical backscattering by biomass burning and sulfate particles derived from sky measurements",1996,"10.1029/95jd02532","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030440425&doi=10.1029%2f95jd02532&partnerID=40&md5=50e1f048a957567c97b6ea38827974c2","Holben et al. [1995] reported measurements of the aerosol spectral optical thickness and derived volume size distribution from measurements of the sky spectral radiance in the aureole (scattering angle &lt;40°). In this paper we use these and other sky data for analysis of the aerosol hemispheric backscattering ratio β for two aerosol types: smoke aerosol, prevailing during the biomass burning season in the Amazon and the Cerrado in 1993, and predominately sulfate aerosol, measured during the Sulfate/Smoke Cloud and Radiation-Atlantic field experiment in the eastern United States in 1993. The β determines the efficiency (per unit of optical thickness) of the aerosol particles to reflect radiation back to space and therefore to generate a negative radiative forcing of climate. The average value of β, using the Wiscombe and Grams [1976] definition, βWG, varied between 0.20 and 0.28 for both aerosol types, as compared to βWG = 0.29 used by Charlson et al. [1992] and Penner et al. [1992] to calculate radiative forcing by sulfate and smoke aerosol, respectively. The variable βWG is an average value of β on all the illumination directions. However, high optical thicknesses occur in the Amazon and eastern United States during the period of July to September, when the solar elevation is high. For these months and the latitude range the actual average value of β is 25% lower than βWG for the same aerosol type. A combination of these two factors results in values of β, and the corresponding aerosol direct radiative forcing, that are 30-50% lower from these estimates. The climate modeling of Kiehl and Briegleb [1993] uses actual computations of the sulfate aerosol hemispherical backscattering as a function of time and geographic position for a particle radius of 0.2 μm, which corresponds very closely to the present results. The volume size distribution, used to derive β, was obtained from sky radiances for scattering angle ≤40°, assuming spherical homogeneous particles. It can be compared with values of β derived from the whole sky almucantar radiance (scattering angle ≤140°) that reflects the true aerosol scattering phase function. The two values of β did not differ significantly."
"7004868225;","Intra-urban nocturnal temperature differences: A multivariate approach",1996,"10.3354/cr007021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030435894&doi=10.3354%2fcr007021&partnerID=40&md5=0ab8cabccd24390d2f77a4997431e02d","The possibility of predicting nocturnal intra-urban air temperature differences on the basis of meteorological data from climatic stations was analysed. Three years of recording at an urban canyon and a nearby open area in the city of Göteborg, Sweden, formed the basis of the analyses. The urban canyon-urban open area temperature differences (ΔTc-o) were best estimated when the data was first classified with reference to the amount of cloud cover and then fitted to a non-linear regression equation which included the wind speed at the urban open area (10 m level). The study shows that the degree of intra-urban temperature variations can be predicted using a fairly simple methodology. The methodology and the general pattern of the model could be helpful as a complementary tool in urban land use planning for cities with a structure similar to Göteborg."
"55499821700;57206332144;7003289221;7003398947;","Scale invariance of liquid water distributions in marine stratocumulus. Part I: Spectral properties and stationarity issues",1996,"10.1175/1520-0469(1996)053<1538:SIOLWD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030469076&doi=10.1175%2f1520-0469%281996%29053%3c1538%3aSIOLWD%3e2.0.CO%3b2&partnerID=40&md5=115c7b25b4d0743ccbc8cb6acb19e89b","This study investigates the internal structure of marine stratocumulus (Sc) using the spatial fluctuations of liquid water content (LWC) measured along horizontal flights off the coast of southern California during the First ISCCP Regional Experiment (FIRE) in summer of 1987. The results of FIRE 87 data analyses are compared to similar ones for marine Sc probed during the Atlantic Stratocumulus Transition Experiment (ASTEX) in summer 1992 near the Azores. In this first of two parts, the authors use spectral analysis to determine the main scale-invariant regimes, defined by the ranges of scales where wavenumber spectra follow power laws; from there, they discuss stationarity issues. Although crucial for obtaining meaningful spatial statistics (e.g., in climate diagnostics), the importance of establishing stationarity - statistical invariance under translation - is often overlooked. The sequel uses multifractal analysis techniques and addresses intermittency issues. By improving our understanding of both nonstationarity and intermittency in atmospheric data, we are in a better position to formulate successful sampling strategies. Comparing the spectral responses of different instruments to natural LWC variability, the authors find scale breaks (characteristic scales separating two distinct power law regimes) that are spurious, being traceable to well-documented idiosyncrasies of the Johnson-Williams probe and forward scattering spectrometer probes. In data from the King probe, the authors find no such artifacts; all spectra are of the scale-invariant form k-β with exponents β in the range 1.1-1.7, depending on the flight. Using the whole FIRE 87 King LWC database, the authors find power-law behavior with β= 1.36 ± 0.06 from 20 m to 20 km. From a spectral vantage point, the ASTEX cloud system behaves statistically like a scaled-up version of FIRE 87; a similar exponent β= 1.43 ± 0.08 is obtained, but the scaling range is shifted to [60 m, 60 km], possibly due to the 2-3 times greater boundary layer thickness. Finally, the authors reassess the usefulness of spectral analysis: • Its main shortcoming is ambiguity: very different looking stochastic processes can yield similar, even identical, spectra. This problem impedes accurate modeling of the LWC data and, ultimately, is why multifractal methods are required. • Its main asset is applicability in stationary and nonstationary situations alike and, in conjunction with scaling, it can be used to detect nonstationary behavior in data. Having β &gt; 1, LWC fields in marine Sc are nonstationary within the scaling range and stationary only at larger scales. Nonstationarity implies long-range correlations, and we demonstrate the damage these cause when trying to estimate means and standard deviations with limited amounts of LWC data."
"6507705108;7005911418;7406715048;","Distributions of surface-layer buoyancy versus lifting condensation level over a heterogeneous land surface",1996,"10.1175/1520-0469(1996)053<1086:DOSLBV>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030453107&doi=10.1175%2f1520-0469%281996%29053%3c1086%3aDOSLBV%3e2.0.CO%3b2&partnerID=40&md5=fa2b6f61622e133950a8f574305a4900","Onset and coverage of small cumulus clouds depend on the relative abundance of surface-layer air parcels possessing favorable buoyancy and moisture - two variables that are coupled through the surface energy budget. This abundance is described using a joint frequency distribution (JFD) as a function of virtual potential temperature θv and height of the lifting condensation level ZLCL. It is shown analytically that the shape and spread of this JFD depends on the ranges of Bowen ratios and solar forcings (albedoes, cloud shading, etc.) that exist within a domain of heterogeneous land use. To sample the character of such JFDs in the real atmosphere, a case study is presented using turbulence data gathered by aircraft flying in the surface layer of southwest France. This case study includes 4 days of clear skies during the Hydrologic Atmospheric Pilot Experiment (HAPEX) of 1986. The full flight track during HAPEX overflew a wide range of land use including evergreen forest, corn, vineyards, pastures, and irrigated fields over varied topography. The JFDs from these full tracks are found to be quite complex, being frequently multimodal with a convoluted perimeter. However, when a full track is broken into segments, each over a subdomain of quasi-homogeneous land use, the resulting segment JFDs are mono-modal with simpler topology. Such a characterization of JFDs provides guidance toward eventual subgrid cumulus parameterization in largescale forecast models, with associated impacts in aviation forecasting, pollutant venting and chemical reactions, vertical dispersion and turbulence modulation, and radiation balance in climate-change models."
"7004442182;6603403884;55543826100;","""Overall"" cloud and snow cover effects on internal climate variables: The use of clear sky climatology",1996,"10.1175/1520-0477(1996)077<2055:CASCEO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030377402&doi=10.1175%2f1520-0477%281996%29077%3c2055%3aCASCEO%3e2.0.CO%3b2&partnerID=40&md5=e692c4d7b78d2bfa6ccc133113d2a49e","This paper is a continuation of empirical studies of cloud and snow cover effects on climate based on a blend of observational meteorological data for the past several decades. It employs the idea that the analysis of climate variability observed during the period of intensive instrumental observations can provide ""overall estimates"" of these effects. A climatology of clear skies for northern extratropical lands is presented in the form of deviations from the average climate conditions. Clouds are an internal component of the climate system, and these deviations indicate specific climate conditions associated with clear skies. At the same time, they may be considered as estimates of the overall cloud effect on the regional climate. A similar approach is applied to estimate the potential effect of snow on the ground, and an attempt is made to divide the effects of snow and clouds."
"7003869084;7004604556;","The influence of greenhouse warming on the atmospheric component of the hydrological cycle",1996,"10.1002/(SICI)1099-1085(199610)10:10<1317::AID-HYP463>3.0.CO;2-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030265348&doi=10.1002%2f%28SICI%291099-1085%28199610%2910%3a10%3c1317%3a%3aAID-HYP463%3e3.0.CO%3b2-5&partnerID=40&md5=e3f2742a5a7267955cfd1740dce49839","An atmosphere-ocean climate box model is used to examine the influence of cloud feedback on the equilibria of the climate system. The model consists of three non-linear ordinary differential equations, which are simplified forms of the first law of thermodynamics for the atmosphere and ocean and the continuity equation for the atmospheric component of the hydrological cycle. The mass continuity equation expresses the cloud liquid water content as a function of the evaporation rate from the ocean surface and the precipitation rate. Cloud formation releases latent heat. The model clouds also absorb solar energy at a rate consistent with recent findings. The model simulates snow-ice albedo feedback, water vapour feedback and cloud feedback. The global mean precipitation and surface temperature are analysed as they respond to enhanced greenhouse warming. Model results show that cloud feedback can lead to the occurrence of multiple climate equilibria. Some of these are warmer than the present equilibrium, with increased precipitation, while others are colder, with reduced precipitation. If the cloud feedback is weak, enhanced greenhouse forcing leads to a small alteration of the present equilibrium. If the cloud feedback is strong enough, the climate system can be forced into a warmer and wetter equilibrium."
"7202208382;7403282069;55411439700;6603568514;","Single-column models and cloud ensemble models as links between observations and climate models",1996,"10.1175/1520-0442(1996)009<1683:SCMACE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030437783&doi=10.1175%2f1520-0442%281996%29009%3c1683%3aSCMACE%3e2.0.CO%3b2&partnerID=40&md5=6a7c3a99ca46bead33bdb95bf5f9d27f","Among the methods that have been devised to test physical parameterizations used in general circulation models, one of the most promising involves the use of field data together with single-column models (SCMs) and/or cloud ensemble models. Here the authors briefly discuss the data requirements of such models and then give several examples of their use. Emphasis is on parameterizations of convection and cloud amount."
"57193132723;7403318365;6507993848;12241892400;","A prognostic cloud water parameterization for global climate models",1996,"10.1175/1520-0442(1996)009<0270:APCWPF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029751999&doi=10.1175%2f1520-0442%281996%29009%3c0270%3aAPCWPF%3e2.0.CO%3b2&partnerID=40&md5=996ae7eeaa77b5a83495e3fcddf42847","An efficient new prognostic cloud water parameterization designed for use in global climate models is described. The scheme allows for life cycle effects in stratiform clouds and permits cloud optical properties to be determined interactively. The parameterization contains representations of all important microphysical processes, including autoconversion, accretion, Bergeron-Findeisen diffusional growth, and cloud/rain water evaporation. Small-scale dynamical processes, including detrainment of convective condensate, cloud-top entrainment instability, and stability-dependent cloud physical thickness variations, are also taken into account. Cloud optical thickness is calculated from the predicted liquid/ice water path and a variable droplet effective radius estimated by assuming constant droplet number concentration. Microphysical and radiative properties are assumed to be different for liquid and ice clouds, and for liquid clouds over land and ocean. The parameterization is validated in several simulations using the Goddard Institute for Space Studies (GISS) general circulation model (GCM). Comparisons are made with a variety of datasets, including ERBE radiative fluxes and cloud forcing, ISCCP and surface-observed cloud properties, SSM/I liquid water path, and SAGE II thin cirrus cover. Validation is judged on the basis of the model's depiction of both the mean state; diurnal, seasonal, and interannual variability; and the temperature dependence of cloud properties. Relative to the diagnostic cloud scheme used in the previous GISS GCM, the prognostic parameterization strengthens the model's hydrologic cycle and general circulation, both directly and indirectly (via increased cumulus heating). Sea surface temperature (SST) perturbation experiments produce low climate sensitivity and slightly negative cloud feedback for globally uniform SST changes, but high sensitivity and positive cloud feedback when tropical Pacific SST gradients weaken with warming. Changes in the extent and optical thickness of tropical cumulus anvils appear to be the primary factor determining the sensitivity. This suggests that correct simulations of upward transport of convective condensate and of Walker circulation changes are of the highest priority for a realistic estimate of cloud feedback in actual greenhouse gas increase scenarios."
"7005204122;57208346904;7501757094;","A regional climate model study of the scale dependence of cloud-radiation interactions",1996,"10.1175/1520-0442(1996)009<1221:ARCMSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030440656&doi=10.1175%2f1520-0442%281996%29009%3c1221%3aARCMSO%3e2.0.CO%3b2&partnerID=40&md5=241928c9cf4ad629593fb5311a3fda28","The scale dependence of cloud-radiation interaction associated with the parameterizations for fractional cloudiness and radiation used in a global climate model is studied by examining the averages, for different spatial scales, of detailed structure of cloudiness and radiation simulated from a regional climate model that incorporates these parameterizations. The regional model simulation is conducted over an area about (360 km)2 located on the southern Great Plains for the period 10-17 April 1994 during which both satellite and surface measurements of radiation fluxes and clouds are available from the Intensive Observing Period of the Atmospheric Radiation Measurement program. The area corresponds approximately to one gridpoint size of a global climate model with horizontal resolution T31. The regional model simulates well the overall cloud and radiation temporal features when averaged over the entire region. However, specific biases exist in the spatial patterns such as the high clouds, the TOA upwelling solar radiation under cloudy conditions, and the net longwave surface flux under clear conditions at night. The cloud and radiation parameterizations are found to be sensitive to the spatial scale of the computation. The diagnosed total cloudiness shows a strong horizontal resolution dependence that leads to large changes in the surface and TOA radiation budgets. An additional experiment, in which the diagnosed cloud at each level is held constant while the radiation parameterization is recalculated, still produces a substantial sensitivity to spatial scale in the calculated radiation quantities. This is because the nature of the cloud vertical overlapping assumption changes as the horizontal scale of the computation varies."
"56165006900;7102577095;","Effects of alternative cloud radiation parameterizations in a general circulation model",1996,"10.1007/s00585-996-0107-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2842517939&doi=10.1007%2fs00585-996-0107-6&partnerID=40&md5=81ce20fd1360e7169145b0dfdb353200","Using the National Center for Atmospheric Research (NCAR) general circulation model (CCM2), a suite of alternative cloud radiation parameterizations has been tested. Our methodology relies on perpetual July integrations driven by ± 2 K sea surface temperature forcing. The tested parameterizations include relative humidity based clouds and versions of schemes involving a prognostic cloud water budget. We are especially interested in testing the effect of cloud optical thickness feedbacks on global climate sensitivity. All schemes exhibit negative cloud radiation feedbacks, i.e., cloud moderates the global warming. However, these negative net cloud radiation feedbacks consist of quite different shortwave and longwave components between a scheme with interactive cloud radiative properties and several schemes with specified cloud water paths. An increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn negative shortwave feedbacks for the interactive radiative scheme, while a decrease in cloud amount leads to a positive shortwave feedback for the other schemes. For the longwave feedbacks, a decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while no distinct changes in effective high cloudiness and the resulting feedback are exhibited for the scheme with interactive radiative properties. The resulting magnitude of negative net cloud radiation feed-back is largest for the scheme with interactive radiative properties. Even though the simulated values of cloud radiative forcing for the present climate using this method differ most from the observational data, the approach shows great promise for the future."
"7401559815;7404653593;7201844203;","Water vapor and cloud feedback over the tropical oceans: Can we use ENSO as a surrogate for climate change?",1996,"10.1029/96GL02414","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030265162&doi=10.1029%2f96GL02414&partnerID=40&md5=61cf076a112f64903dd4439c914ea5ce","Based on experiments with the Goddard Earth Observing System (GEOS) global climate model, we find that the basic patterns of anomalous water vapor greenhouse effect and cloud radiative forcing during ENSO are primarily determined by the basin-wide dynamical response to large scale sea surface temperature (SST) forcing. There is no supergreenhouse effect in the sense of unstable interaction due to local thermodynamics and water vapor radiative feedback on interannual time scales. About 80% of the clear sky water vapor greenhouse sensitivity to SST deduced from ENSO anomalies are due to the transport of water vapor by the large scale circulation. The sensitivity of water vapor greenhouse effect to SST due to radiative feedback is found to be about 1.8 Wm-2/°C, much smaller than the values of 6-9 Wn-2/°C previously estimated from satellite observations from ENSO conditions. Our results show that regionally based interannual variability should not be used to infer radiative feedback sensitivity for climate change unless proper corrections are made for the effect of the large scale circulation. Copyright 1996 by the American Geophysical Union."
"7201783608;57198502962;","The sensitivity of climate simulations to the specification of mixed phase clouds",1996,"10.1007/BF00216271","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030367750&doi=10.1007%2fBF00216271&partnerID=40&md5=c7b9dc347053d35453e2117ea6281f7f","In the prognostic stratiform cloud scheme used in the UK Meteorological Office Unified Model, mixed phase clouds are assumed to exist between 0 and -15°C. Recent observations of such clouds, carried out using the C-130 aircraft of the Meteorological Research Flight, suggest that a smaller range of 0 to -9°C may be more appropriate. The sensitivity of cloud and radiation fields as simulated by a 5x7.5° latitude-longitude version of the Unified Model to such a reduction in the temperature range of mixed phase clouds is considered. Using a smaller temperature range systematic errors in the radiation budget of the model are reduced in mid-latitudes, bringing the model into closer agreement with ERBE data. The sensitivity of model albedo to an increase in the temperature range over which mixed phase clouds are assumed to exist, suggested by previous observational studies, is also considered together with the impact of removing the mixed phase part of the precipitation parametrization altogether."
"7501956187;56744278700;","Sensitivity of simulated global climate to perturbations in low-cloud microphysical properties. Part I: Globally uniform perturbations",1996,"10.1175/1520-0442(1996)009<1385:SOSGCT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030434993&doi=10.1175%2f1520-0442%281996%29009%3c1385%3aSOSGCT%3e2.0.CO%3b2&partnerID=40&md5=3bf80c430410b4b44f31eb9381c25cab","The sensitivity of the global climate to perturbations in the microphysical properties of low clouds is investigated using a general circulation model coupled to a static mixed layer ocean with fixed cloud distributions and incorporating a new broadband parameterization for cloud radiative properties. A series of GCM experiments involving globally uniform perturbations in cloud liquid water path or effective radius (albedo perturbations), along with one for a doubling of carbon dioxide (greenhouse perturbation), lead to the following results: 1) The model's climate sensitivity (ratio of global-mean surface temperature response to the global-mean radiative forcing) is virtually independent (to ∼10%) of the sign, magnitude, and the spatial pattern of the forcings considered, thus revealing a linear and invariant nature of the model's global-mean response. 2) Although the total climate feedback is very similar in all the experiments, the strengths of the individual feedback mechanisms (e.g., water vapor, albedo) are different for positive and negative forcings. 3) Changes in moisture, tropospheric static stability, and sea ice extent govern the vertical and zonal patterns of the temperature response, with the spatial distribution of the response being quite different from that of the radiative forcing. 4) The zonal surface temperature response pattern, normalized with respect to the global mean, is different for experiments with positive and negative forcings, particularly in the polar regions of both hemispheres, due to differing changes in sea ice. 5) The change in the surface radiative fluxes is different for the carbon dioxide doubling and cloud liquid water path decrease experiments, even though both cases have the same radiative forcing and a similar global-mean surface temperature response; this leads to differences in the vigor of the hydrologic cycle (evaporation and precipitation rates) in these two experiments."
"55745955800;7005070958;7401936984;","Relationship between cloud radiative forcing and sea surface temperatures over the entire tropical oceans",1996,"10.1175/1520-0442(1996)009<1374:RBCRFA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030517143&doi=10.1175%2f1520-0442%281996%29009%3c1374%3aRBCRFA%3e2.0.CO%3b2&partnerID=40&md5=f489af27cb76103d27383667a30a0d11","Satellite measurements from January 1985 to December 1989 show that warmer tropical oceans as a whole are associated with less longwave greenhouse effect of clouds and less cloud reflection of solar radiation to the space. The regression slopes of longwave and shortwave cloud radiative forcings against sea surface temperatures averaged from 30°N to 30°S are about -3 and 2 W m-2 K-1, respectively. Relationships of cloud forcings and sea surface temperatures are analyzed for regions with different sizes. As has been reported in previous studies, the magnitude of area-averaged cloud radiative forcing for both longwave and shortwave radiations increases with sea surface temperatures in the equatorial eastern Pacific and is insensitive to sea surface temperatures over the tropical Pacific basin. Yet, when the region extends beyond the tropical Pacific, the magnitude decreases with sea surface temperatures. This phenomenon is shown to relate to changes in clouds over the tropical Indian Ocean and Atlantic, where sea surface temperatures increased but clouds decreased during the 1987 El Niño event. Relevance of the results to other climate changes is discussed."
"7004325649;7004286811;7201635744;7408202424;7406741310;55471740500;","Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment",1996,"10.1175/1520-0477(1996)077<0853:CATERE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030425244&doi=10.1175%2f1520-0477%281996%29077%3c0853%3aCATERE%3e2.0.CO%3b2&partnerID=40&md5=bb8eba96792932566e70fa6e602c5e0f","Clouds and the Earth's Radiant Energy System (CERES) is an investigation to examine the role of cloud/radiation feedback in the Earth's climate system. The CERES broadband scanning radiometers are an improved version of the Earth Radiation Budget Experiment (ERBE) radiometers. The CERES instruments will fly on several National Aeronautics and Space Administration Earth Observing System (EOS) satellites starting in 1998 and extending over at least 15 years. The CERES science investigations will provide data to extend the ERBE climate record of top-of-atmosphere shortwave (SW) and longwave (LW) radiative fluxes. CERES will also combine simultaneous cloud property data derived using EOS narrowband imagers to provide a consistent set of cloud/radiation data, including SW and LW radiative fluxes at the surface and at several selected levels within the atmosphere. CERES data are expected to provide top-of-atmosphere radiative fluxes with a factor of 2 to 3 less error than the ERBE data. Estimates of radiative fluxes at the surface and especially within the atmosphere will be a much greater challenge but should also show significant improvements over current capabilities."
"35453194100;7003455444;7202840464;","Characteristics of Arctic Ocean climate based on COADS data, 1980-1993",1996,"10.1029/96GL01807","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030200082&doi=10.1029%2f96GL01807&partnerID=40&md5=b392ccd3ec7b717a8074730deb77e989","Arctic Ocean cloud cover, precipitation frequency and temperature are examined using COADS records for the period 1980-1993. Principal component analysis reveals two climatic regions, the 'Northern Atlantic' and 'Central Arctic', as well as a cold (November-April) and warm (June-September) season. For the Central Arctic, precipitation frequency and cloud cover peak during the warm season, with liquid precipitation comprising about 50% of all precipitation reports during July. For the Northern Atlantic, precipitation frequency and the frequency of moderate/heavy precipitation peak during the cold season, but with relatively constant cloud cover throughout the year. Liquid precipitation is common in all months, comprising the bulk of reports from June through September. Based on our analysis, the proposed location for the 1997-1998 Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment cannot be considered Central Arctic in character. Copyright 1996 by the American Geophysical Union."
"7005212820;7202208382;","Liquid and ice cloud microphysics in the CSU general circulation model. Part III: Sensitivity to modeling assumptions",1996,"10.1175/1520-0442(1996)009<0561:LAICMI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029729920&doi=10.1175%2f1520-0442%281996%29009%3c0561%3aLAICMI%3e2.0.CO%3b2&partnerID=40&md5=c9318458fcd501d8b196dacf64997f51","The inclusion of cloud microphysical processes in general circulation models makes it possible to study the multiple interactions among clouds, the hydrological cycle, and radiation. The gaps between the temporal and spatial scales at which such cloud microphysical processes work and those at which general circulation models presently function force climate modelers to crudely parameterize and simplify the various interactions among the different water species (namely, water vapor, cloud water, cloud ice, rain, and snow) and to use adjustable parameters to which large-scale models can be highly sensitive. Accordingly, the authors have investigated the sensitivity of the climate, simulated with the Colorado State University general circulation model, to various aspects of the parameterization of cloud microphysical processes and its interactions with the cumulus convection and radiative transfer parameterizations. The results of 120-day sensitivity experiments corresponding to perpetual January conditions have been compared with those of a control simulation in order to 1) determine the importance of advecting cloud water, cloud ice, rain, and snow at the temporal and spatial scale resolutions presently used in the model; 2) study the importance of the formation of extended stratiform anvils at the tops of cumulus towers; 3) analyze the role of mixed-phase clouds in determining the partitioning among cloud water, cloud ice, rain, and snow and, hence, their impacts on the simulated cloud optical properties; 4) evaluate the sensitivity of the atmospheric moisture budget and precipitation rates to a change in the fall velocities of rain and snow; 5) determine the model's sensitivity to the prescribed thresholds of autoconversion of cloud water to rain and cloud ice to snow; and 6) study the impact of the collection of supercooled cloud water by snow, as well as accounting for the cloud optical properties of snow. Results are presented in terms of 30-day mean differences between the sensitivity experiments and control run. The authors find that three-dimensional advection of the water species has little influence on their geographical distributions and globally averaged amounts. The simulated climate remains unchanged when detrained condensed water at the tops of cumulus towers is used as a source of rain and snow rather than as a source of cloud water and cloud ice. In contrast, instantaneously removing cloud water and cloud ice detrained at the tops of cumulus towers in the form of precipitation yields a strong drying of the atmosphere and a significant reduction in the size of the anvils. Altering the partitioning between cloud ice and supercooled cloud water produces significant changes in the vertical distributions of the cloud optical depth and effective cloud fraction, hence producing significant variations in the top-of-the-atmosphere longwave and shortwave cloud radiative forcings. Increasing the fall speeds of rain and snow leads to a decrease in cloudiness and an increase in stratiform rainfall. Increasing the thresholds for autoconversion of cloud water to rain and cloud ice to snow yields a significant increase in middle- and high-level clouds and a reduction of the cumulus precipitation rate. The collection of supercooled cloud water by snow appeared to be an important microphysical process for mixed-phase clouds. Finally, the optical effects of snow have little impact upon the top-of-the-atmosphere radiation budget. This study illustrates the need for in-depth analysis of the spatial and temporal scale dependence of the different microphysical parameters of the cloud parameterizations used in general circulation models."
"56000281400;7007108728;","The relationship between cloud droplet and aerosol number concentrations for climate models",1996,"10.1002/(SICI)1097-0088(199608)16:8<941::AID-JOC57>3.0.CO;2-O","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030425159&doi=10.1002%2f%28SICI%291097-0088%28199608%2916%3a8%3c941%3a%3aAID-JOC57%3e3.0.CO%3b2-O&partnerID=40&md5=9efb8072ae30f62e56f1827521a40cf8","Aerosols have an effect on cloud droplet size and concentration, and thus affect the radiative properties of clouds. The purpose of this study is to develop parameterized equations between droplet number concentration (Nd) and total aerosol number concentration (Va) for use in numerical weather prediction models and global climate models. In situ observations of droplet and aerosol number concentrations collected during four field projects are used. Variables Nd and Na for stratus and stratocumulus clouds are averaged over 10-km lengths to represent scales close to those used in these models. The Nd value is added to the interstitial aerosol number concentration (Ni) to obtain in cloud Na. The relationships generated are compared with current parameterizations. The results suggest that parameterized equations obtained from three field projects, representing clouds formed over land, are similar. The fourth one, representing clouds over ocean, is found similar to the other three for lower concentration of Na, but different for higher values of Na. The value of Nd in clouds generally increases with Na. This suggests that the relationship between Nd and Na may be universal. However, local variability can be very important."
"7103010852;","The greenhouse Earth: A view from space",1996,"10.1256/smsqj.53201","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030478274&doi=10.1256%2fsmsqj.53201&partnerID=40&md5=42976b3cf90c95a5555935837e0d6e1f","The natural greenhouse effect of the Earth is strongly influenced by the radiative effects of water vapour and clouds in the atmosphere, which control the energy absorbed from the sun, and that lost through thermal emission to space. Any perturbations to the climate balance, for example through so-called 'radiative forcing' due to increasing CO2 amounts, variations in solar constant, or other causes, can be amplified by the feedback processes that involve water in its various phases. The radiative cooling of the Earth in the absence of clouds has recently been shown to be dominated by emission from upper-tropospheric water vapour, in the far infrared portion of the spectrum, and this is illustrated: observations of this radiative flux, and of the distribution of water vapour in the upper troposphere, are urgently needed. The role of clouds is discussed, and it is noted that their response to global warming is not presently unambiguously determined with available models, due to the complexity of competing processes: again, as in the cloud-free case, more accurate global observations are needed. The paper is illustrated by data from satellite experiments, most notably the Earth Radiation Budget Experiment sponsored by NASA."
"7006377579;11440377600;56128808100;7006235542;35552588700;55454856700;7006728825;6701657620;","A parametrization of the ice water content observed in frontal and convective clouds",1996,"10.1002/qj.49712253605","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030326338&doi=10.1002%2fqj.49712253605&partnerID=40&md5=eb0b050625e51f6297eaea829c87278a","The properties of the ice phase in a number of cloud types are investigated to improve the ice phase parametrization in atmospheric global-climate models. Frontal clouds over southern England and the sea areas around the British Isles, maritime convective clouds over the North Atlantic, and continental convective clouds over New Mexico and Montana in the USA are studied. Ice concentrations are seen to be several orders of magnitude higher than those which could be attributed to primary nucleation of ice nuclei at cloud-top temperatures. Thus secondary ice multiplication processes must be operating in each cloud type. Evidence suggests that the process of ice splinter production during riming, the Hallett-Mossop process which operates at temperatures around -6 °C, is the dominant mechanism operating. The data analysed are parametrized as phase ratios, the fraction of cloud condensed water found in the liquid phase, and the variation of this phase ratio with temperature is examined. The greatest differences are observed between frontal and convective clouds, although smaller differences between continental and maritime clouds of the same type are also seen. In general, frontal clouds possess very high fractions of ice across a wide range of temperature. In contrast, convective clouds exhibit a wide range of phase ratio across the whole temperature range observed. These differences are attributed to the greater vertical wind velocities present in convective clouds. These parametrizations have been used in the UK Meteorological Office Global Climate Model. They are valid for clouds which span the Hallett-Mossop splinter-production temperature range."
"7403442230;7003635928;","Near-infrared spectral measurements of liquid water absorption by clouds",1996,"10.1029/96GL01473","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030183035&doi=10.1029%2f96GL01473&partnerID=40&md5=7b0a918cf882ab4e38a671f89e24b16f","Spectral measurements of the solar flux in the near-infrared region using an FTIR spectrometer have yielded important information concerning the absorption of solar radiation by clouds. A comparison of the spectra of solar fluxes for clear and overcast sky conditions measured from the ground for a northern mid-latitude location demonstrates that about 118 W/m2 of the solar radiation is absorbed preferentially by clouds in the 3,000 - 10,000 cm-1 region. The cloud radiative forcing ratio was estimated to be 1.24. Climate model calculations generally predict that clouds mainly scatter solar radiation while absorbing on average about 4% of the extraterrestrial insolation. The interaction of solar radiation with clouds may be dominated by the absorption of liquid water rather than by scattering, particularly if a sufficient number of liquid water droplets reside in the upper reaches of a cloud. This may contribute, in part, to the anomalous cloud absorption effect. Copyright 1996 by the American Geophysical Union."
"6603631763;7401456188;","Finite-cloud effects in longwave radiative transfer",1996,"10.1175/1520-0469(1996)053<0953:FCEILR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030482831&doi=10.1175%2f1520-0469%281996%29053%3c0953%3aFCEILR%3e2.0.CO%3b2&partnerID=40&md5=1c21403d8f16bc089ef458ed271b86b5","Numerical weather and climate prediction models demand more accurate treatment of clouds. In this research, finite-cloud effects are defined as the influence of cloud shape, size, and spatial arrangement on longwave radiative transfer. To show the magnitude of these effects, radiometer data collected in 1992 during the Atlantic Stratocumulus Transition Experiment (ASTEX) were analyzed. The ASTEX data showed that radiative transfer calculations that ignored the vertical dimensions of the clouds underestimated the longwave cloud radiative surface forcing by 30%, on average. To study further these finite-cloud effects, a three-dimensional 11-μ radiative transfer model was developed. Results from this model, which neglected scattering, agreed with the measurements taken during ASTEX on 14 June 1992."
"55745955800;","Impact of the convection-wind-evaporation feedback on surface climate simulation in general circulation models",1996,"10.1007/BF00231104","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029730168&doi=10.1007%2fBF00231104&partnerID=40&md5=82fc1518888b175831ca0e7ec757c438","The wind-evaporation-convection feedback in the tropics is demonstrated to strongly affect the mean state of surface climate in atmospheric general circulation models. The feedback is shown to be very effective in channeling perturbations from one component of the climate system to other components, e.g., from evaporation to surface wind and from atmospheric convective activity to evaporation. It also provides an effective channel to pass on atmospheric perturbations in the middle and upper troposphere to the surface. As an illustration, it is shown that surface evaporation over tropical oceans is connected with cloud absorption of shortwave radiation through this feedback. Insufficient shortwave cloud absorption, causing excessive shortwave radiation at the surface as is common in most of the climate models, leads to excessive evaporation. Quantitatively, sensitivity of evaporation to short-wave cloud absorption, when averaged over the whole tropics, can be described by an approximate balance of variations in atmospheric radiative cooling and latent heating. This balance is achieved by the impact of radiation on convection, and then on the surface wind and evaporation. This mechanism calls for the need to include atmospheric processes far beyond the surface for improvements of the quality of surface climate simulation."
"7501956187;56744278700;","Sensitivity of simulated global climate to perturbations in low cloud microphysical properties. Part II: Spatially localized perturbations",1996,"10.1175/1520-0442(1996)009<2788:SOSGCT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030378165&doi=10.1175%2f1520-0442%281996%29009%3c2788%3aSOSGCT%3e2.0.CO%3b2&partnerID=40&md5=60198f207cd41f107d4d6e278d898811","The sensitivity of the global climate to spatially localized (20°-70°N) perturbations in the microphysical properties of low clouds is investigated using a general circulation model coupled to a mixed layer ocean with fixed cloud distributions. By comparing with earlier experiments involving globally uniform perturbations, in-sights are obtained into the climate responses to spatially inhomogeneous radiative forcings, such as that due to the contrast in the effective drop radius of land and ocean clouds and the anthropogenic sulfate aerosol-induced alteration of cloud albedo. The main findings of this study are as follows: 1) The model's climate sensitivity (ratio of global-mean surface temperature response to the global-mean radiative forcing) is virtually independent of the distribution and magnitude of forcing. 2) Although the total feedback is very similar in the different experiments, the strengths of the individual feedback mechanisms (water vapor, albedo, lapse rate) are dissimilar. 3) For the localized perturbations, the climate response is essentially confined to the hemisphere in which the forcing occurs, owing to a poor interhemispheric energy exchange. 4) In spite of no forcing in the Southern Hemisphere in the localized experiments, there is a weak ""remote"" temperature response there. 5) For both global and localized perturbations, the temperature response in the tropical upper troposphere is larger than in the lower troposphere due to moist convective processes; in the localized experiments, while there is a strong vertical gradient in the temperature change at the Northern Hemisphere mid and high latitudes, the temperature change throughout the lower and midtroposphere of the Southern Hemisphere is uniform. 6) The localized experiments induce notable changes in the mean meridional circulation and precipitation near the equator, which are not obtained for the global perturbation cases. 7) The pattern of temperature response of the land and ocean areas in the Northern Hemisphere midlatitudes depends on whether the forcing occurs over both types of surfaces or over land only; the results suggest that the well-known contrast in drop radii between continental and maritime clouds exerts a significant influence on the surface temperature distribution within the zone and on the manner in which the surface energy balance is maintained."
"7003430284;","Observations Pertaining to the Effect of Chemical Transformation in Cloud on the Anthropogenic Aerosol Size Distribution",1996,"10.1080/02786829608965388","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030219650&doi=10.1080%2f02786829608965388&partnerID=40&md5=48f77fbccbb5beb8f4f9189bd1db3cde","Airborne observations from two case studies of continental cloud, one of summertime cumulus and one of autumn stratus, are examined for evidence of changes in the size of the accumulation-mode aerosol particles due to S(IV) oxidation in cloud. Such changes might affect the efficiency with which the aerosol scatters light and its ability to function as cloud condensation nuclei (CCN), and hence impact climate. In both cases, there were strong anthropogenic contributions to the aerosol, and the measured particles (0.17–2 μm in diameter) were not scavenged with 100% efficiency: the relative number concentrations of measured particles activated in cloud were about 70% for the cumulus and 15%-50% for the stratus. Within the measurement resolution, the apparent effect of cloud processing in the cumulus case was to nearly preserve the shape of the size distribution of the measured aerosol, even after the mass addition of sulfate by S(IV) oxidation. This can be accomplished through the activation of sufficiently small particles to balance the increase in larger particles. In the stratus case, the aerosol size distributions associated with the cloud are bimodal with peaks at 0.23 and 0.35 μm. The second peak coincides closely with the lower size of particles activated in the cloud suggesting that S(IV) oxidation or possibly coalescence scavenging contributed to its formation. © 1996 Taylor & Francis Group, LLC."
"7005070958;","Cloud feedback in atmospheric general circulation models: An update",1996,"10.1029/96JD00822","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030449120&doi=10.1029%2f96JD00822&partnerID=40&md5=5a320b6b6a5d4a7638fb31ba090d6ab4","Six years ago, we compared the climate sensitivity of 19 atmospheric general circulation models and found a roughly threefold variation among the models; most of this variation was attributed to differences in the models' depictions of cloud feedback. In an update of this comparison, current models showed considerably smaller differences in net cloud feedback, with most producing modest values. There are, however, substantial differences in the feedback components, indicating that the models still have physical disagreements. Copyright 1996 by the American Geophysical Union."
"7202048299;7004014731;","Diurnal variations of cloud cover and their relationship to climatological conditions",1996,"10.1175/1520-0442(1996)009<2802:DVOCCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030392920&doi=10.1175%2f1520-0442%281996%29009%3c2802%3aDVOCCA%3e2.0.CO%3b2&partnerID=40&md5=1be2c7c73e4470e67f876fe88b732e44","The ISCCP-C2 cloud climatology is used to describe the three-dimensional structure of cloud diurnal variations and to investigate their relationship to local climatological conditions. The latter follows from the regression of diurnal components onto climatological state variables. Four important diurnal cloud categories are identified. The diurnal variation of maritime high-cloud fraction C′hi maximizes at 1700 local solar time (LST) and is strongest over maritime convective locations where the mean high-cloud fraction is C̄hi &gt; 0.1. The diurnal variation of maritime low-cloud fraction maximizes at 0400 LST and is strong over maritime nonconvective locations where C̄hi &lt; 0.1. Diurnal variations of high-cloud fraction (persistent during the night, minimum at 1100 LST) and low-cloud fraction (1300 LST maximum) are strong over all continental locations in the latitude band 40°S-40°N. In each cloud category, most of the diurnal amplitude and phase at individual locations is explained by the regression of diurnal amplitude onto only three climatological state variables. For most categories, the diurnal amplitude has its strongest relationship with mean cloud fraction. The relationship between relative diurnal amplitude (amplitude divided by the mean) and other climatological properties is then particularly meaningful. The relative amplitude of maritime high-cloud fraction is related to the mean total-cloud fraction and the noontime solar zenith angle, which measures the solar diurnal amplitude. The diurnal amplitude of maritime low-cloud fraction does not have its strongest relationship with the mean low-cloud fraction, but has strong relationships to the upper-level cloud fraction, cloud-top height, and the solar diurnal amplitude. The relative amplitude of continental high-cloud fraction is related most strongly to the time-mean surface temperature, the diurnal amplitude of surface temperature, and the solar diurnal amplitude. The relative amplitude of continental low-cloud fraction has strong relationships with atmospheric moisture content and the diurnal amplitude of surface temperature. In contrast to amplitude, diurnal phase does not exhibit a strong relationship with any climatological variable. Instead, it is uniform within individual categories, which makes cloud diurnal variations independent of geographical location and, therefore, highly spatially coherent. The spatial coherence of cloud diurnal variations makes them an important ingredient of climate, one that affords some predictability in terms of local climatological conditions."
"7201472576;","Validation of modelled cloudiness using satellite-estimated cloud climatologies",1996,"10.3402/tellusa.v48i5.12206","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030404855&doi=10.3402%2ftellusa.v48i5.12206&partnerID=40&md5=520cffd573a0cc40e462d878a097fe10","A method to evaluate forecasts of total fractional cloud cover using satellite measurements is demonstrated. Cloud analyses in the form of monthly cloud climatologies are extracted from NOAA AVHRR data which are compared to corresponding cloud forecast information from the HIRLAM and ECMWF numerical weather prediction models. The satellite-based cloud information is extracted for a summer month in 1994 and a winter month in 1995 by use of the SMHI cloud classification model SCANDIA. Cloud analyses are conducted for an area covering a substantial part of northern Europe. Deficiencies in forecasted cloud amounts are found for both models, especially the underestimation of cloudiness for short forecast lengths with the HIRLAM model. Forecast improvements using the HIRLAM model are indicated when introducing a cloud initialisation technique using cloud fields from initial 6-hour forecasts (first-guess fields). Future systematic validations using this technique are, however, needed to make firm conclusions on the general model behaviour. SCANDIA-derived cloud information is proposed as a valuable complement to other datasets used for cloud forecast validation (e.g., the SSM/I- and ISCCP data sets)."
"7004047498;7006595513;6602693652;","Occurrence of ultrafine particles in association with orographic clouds",1996,"10.1016/0021-8502(96)00085-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030233476&doi=10.1016%2f0021-8502%2896%2900085-7&partnerID=40&md5=16f5bde828475ca6d28ef9555a3bed74","Ultrafine aerosol particles affect the climate by directly contributing to radiative forcing or acting as cloud condensation nuclei. A study was undertaken to measure the size distributions of the submicron aerosol at Great Dun Fell in Northern England where the air is anthropogenically influenced using the Differential Mobility Particle Sizing technique. These measurements, in addition to other physical, chemical, and meteorological measurements, constitute part of a combined effort to better understand cloud processes and their climatic impact."
"56322980300;7007025149;","Impacts of the Great Lakes on regional climate conditions",1996,"10.1016/S0380-1330(96)71006-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030300667&doi=10.1016%2fS0380-1330%2896%2971006-7&partnerID=40&md5=cdf42553bd61556b034f43059fb84c37","Estimates of lake-induced spatial changes of six climate variables (precipitation, mean minimum and mean maximum temperatures, cloud cover, vapor pressure, and wind speed) were derived for the entire Great Lakes basin. These patterns were estimated by a comparison of maps of each weather variable using: (1) all regional climate data, and (2) regional data when observations within an 80-km zone around the lakes were removed. Results generally confirm expectations and prior findings, but point to inadequacies in data collection that limit a highly precise analysis. Lake effects are most noticeable in precipitation and temperature and vary considerably by season, time of day, and lake size. Greatest lake influences are found near Lake Superior where up to 100% more precipitation falls downwind of the lake in winter compared to that expected without its presence. During summer, all lakes cause a downwind decrease in rainfall of 10% to 20%. Mean minimum temperatures in the basin are higher in all seasons and over all lakes. Lake- induced reductions in mean maximum temperatures in the region are observed during spring and summer. Effects on cloud cover are greatest during winter and show increases of approximately 25% in areas downwind of Lakes Superior and Michigan. Conversely, the cool summertime waters of Lakes Michigan and Huron reduce cloudiness roughly 10%. Variations in vapor pressure are consistent with observed changes in temperature. Amounts in winter are estimated to be 10% to 15% higher across the center of the basin, but decrease by roughly 5% to 10% at many lake shore sites in summer. Seasonal wind speed data were considered to lack an appropriate number of quality long-term climate stations to determine spatial lake effects. Surface elevations, increasing east of the basin, complicated detection of effects due solely to the lakes."
"6701354598;7004511627;","Determination of cloud amount and level from radiosonde soundings",1996,"10.1175/1520-0450(1996)035<1362:docaal>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030432034&doi=10.1175%2f1520-0450%281996%29035%3c1362%3adocaal%3e2.0.co%3b2&partnerID=40&md5=07ddfbb9bcd9428a4b7cfcb015bfa1fb","A method developed in the former Soviet Union for predicting cloud amounts is supplemented with a new method of determining the base and tops of clouds. Criteria for predicting a cloud layer are 0 ≤ T″(z) and R″(z) ≤ 0, where T″ is the second derivative of the vertical profile of temperature and R″ is the second derivative of the relative humidity. This test was found from an analyses of United States radiosonde data. Cloud amount (sky cover) is predicted from a relationship between cloud amount and dewpoint depression within the predicted cloud layer and the temperature at that level. This relationship is based on data from the former Soviet Union and data from the Indian Ocean and divides cloud amount into four categories: 0%-20%, 20%-60%, 60%-80%, and 80%-100% coverage. The new composite method is evaluated using data from several United States radiosonde stations within different climates. Evaluation data was selected to include only situations in which the observer (providing the ""truth"") could see only one cloud layer. Consequently, the evaluation is biased toward stratified cloud conditions. The method will provide cloud information that can be used in models of radiosonde sensors to adjusted temperature data."
"55087038900;","An accurate parameterization of the solar radiative properties of cirrus clouds for climate models",1996,"10.1175/1520-0442(1996)009<2058:AAPOTS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030417913&doi=10.1175%2f1520-0442%281996%29009%3c2058%3aAAPOTS%3e2.0.CO%3b2&partnerID=40&md5=85b3fe364f9588961d55ee7d17a3c61c","An accurate parameterization of the solar radiative properties of cirrus clouds is developed based on improved light scattering calculations. Here 28 ice crystal size distributions from in situ aircraft observations in both tropical and midlatitude regions are employed. In the single scattering calculations, the most recent measurements of the imaginary refractive indices of ice are used, thereby eliminating a large existing uncertainty. The single scattering properties of hexagonal ice crystals are calculated by using an improved geometric ray-tracing program that can produce accurate results for size parameters larger than 15. A generalized effective size, Dge, is defined to account for the ice crystal size distribution in the radiative calculations. Based on physical principles, the single scattering properties have been parameterized in terms of ice water content (IWC) and Dge. This allows the cirrus cloud single scattering properties to respond independently to changes in IWC or Dge. The generalized effective size can be related to the total cross-sectional area of ice particles per unit volume, a quantity directly measured by the 2D optical probe in in situ microphysical observations of cirrus clouds. The present parameterization of the extinction coefficient and the single scattering albedo in terms of IWC and Dge can be properly applied to cirrus clouds that contain various nonspherical particles, such as plates, columns, bullet rosettes, and aggregates, etc. The present parameterization of the single scattering properties of cirrus clouds is evaluated by examining the bulk radiative properties for a wide range of atmospheric conditions. Compared with reference results, the typical relative errors due to the parameterization are ∼1.2%, ∼0.3%, and ∼2.9% in reflectance, transmittance, and absorptance, respectively. The accuracy of this parameterization guarantees its reliability in applications to climate models. Cloud absorption plays an important role in cloud-radiation interactions and therefore in climate systems. Because of the large variation in the co-albedo of ice near the wavelength of 1.41 μm, one of the spectral divisions is chosen at 1.41 μm to predict cloud absorption properly. Furthermore, the averaging technique for single scattering albedo in spectral intervals associated with absorption bands is important for the parameterization of radiative properties of ice clouds."
"6601992858;6603106251;","Global modeling of cloud radiative effects using ISCCP cloud data",1996,"10.1175/1520-0442(1996)009<1479:GMOCRE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030429005&doi=10.1175%2f1520-0442%281996%29009%3c1479%3aGMOCRE%3e2.0.CO%3b2&partnerID=40&md5=17013bec54a6b6f0d9583802e8839c29","Cloud radiative effects are represented in simulations with the general circulation model of the Navy Operational Global Atmospheric Prediction System (NOGAPS) using ingested cloud field data from the ISCCP dataset rather than model-diagnosed cloud fields. The primary objective is to investigate the extent to which the high temporal resolution ISCCP data can be used to improve the simulation of cloud radiative effects on the general circulation in GCM simulations much as observed sea surface temperatures (SSTs) have been used to avoid simulation errors resulting from inaccurately modeled SSTs. Experiments are described that examine the degree to which uncertainties in cloud field vertical structure impair the utility of the observed cloud data in this regard, as well as the extent to which unrealistic combinations of cloud radiative forcing and other physical processes may affect GCM simulations. The potential for such unrealistic combinations stems from the lack of feedback to the cloud fields in simulations using ingested cloud data in place of model-predicted cloud fields. Simulations for the present work were carried out for three April through July periods (1986-1988) using prescribed sea surface temperatures. Analysis of the model results concentrated primarily on the month of July, allowing for a 3-month spinup period. Comparisons with ERBE data show the expected improvement in the simulation of top of the atmosphere radiation fields using the observed cloud data. Three experiments are described that examine the model sensitivity to the vertical structure assumed for the cloud fields. The authors show that although uncertainties in assumed vertical profiles of cloudiness may possibly have significant effects on certain aspects of our simulations, such effects do not appear to be large in terms of monthly mean quantities except in the case of large errors in cloud field vertical profiles. Precipitation fields are particularly insensitive to such uncertainties. A preliminary investigation of potential inaccuracies in our representation of cloud radiative effects with ISCCP data resulting from unrealistic combinations of cloud radiative forcing and other physical processes is made by comparing simulations with 3-hourly and monthly mean cloud fraction data. The authors find little difference in the simulation of monthly mean quantities in spite of large differences in the temporal variability of the imposed ISCCP-based cloud radiative forcing in these simulations. These results do not preclude the importance of simulating the correct temporal relationship between cloud radiative forcing and other physical processes in climate model simulations, but they do support the assumption that a correct simulation of that relationship is not essential for the simulation of certain monthly mean quantities. The present results point favorably to the use of the ISCCP cloud data for climate model testing, as well as further GCM experiments examining the radiative effects of clouds on the general circulation."
"7005365571;57193916375;7004155816;7003714243;","The atmospheric boundary layer - advances in knowledge and application",1996,"10.1007/BF00122485","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030424562&doi=10.1007%2fBF00122485&partnerID=40&md5=2e5d30a9fb4cc40caba246430567609c","Summarises major activities and advances in boundary-layer knowledge in the 25 years since 1970, with emphasis on the application of this knowledge to surface and boundary-layer parametrisation schemes in numerical models of the atmosphere. Progress in three areas is discussed: the mesoscale modelling of selected phenomena; numerical weather prediction; and climate simulations. Future trends are identified, including the incorporation into models of advanced cloud schemes and interactive canopy schemes, and the nesting of high resolution boundary-layer schemes in global climate models."
"55969830400;7006393267;7003295256;","Impact of clouds on surface radiative fluxes and snowmelt in the arctic and subarctic",1996,"10.1175/1520-0442(1996)009<2110:IOCOSR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030407243&doi=10.1175%2f1520-0442%281996%29009%3c2110%3aIOCOSR%3e2.0.CO%3b2&partnerID=40&md5=5bcc45ee8f6a776e7e578299f5674ef6","A comprehensive atmospheric radiative transfer model combined with the surface energy balance equation is applied to investigate the impact of clouds on surface radiative fluxes and snowmelt in the Arctic and subarctic. Results show that at the surface, the shortwave cloud-radiative forcing is negative, while the longwave forcing is positive and generally much larger than the shortwave forcing. Thus, the all-wave surface cloud-radiative forcing is positive, with clouds warming the lower atmosphere and enhancing snowmelt during the melting period in the Arctic and subarctic. These results agree with and explain observations and measurements over the past three decades showing that the onset of snowmelt starts earlier under cloudy sky conditions than under clear sky conditions in the Arctic. Clouds could change the date of onset of snowmelt by as much as a month, which is of the order of the observed interannual variations in the timing of snowmelt in the Arctic and subarctic. The all-wave cloud radiative forcing during the period of snowmelt reaches a maximum at equivalent cloud droplet radius (re) of about 9 μm, and cloud liquid water path of about 29 g m-2. For thin clouds, the impact of changes in liquid water path on all-wave cloud radiative forcing is greater than changes in equivalent cloud droplet size, while for thick clouds, the equivalent cloud droplet size becomes more important. Cloud-base temperature and to a minor extent cloud-base height also influence the surface radiative fluxes and snowmelt. This study indicates that the coupling between clouds and snowmelt could amplify the climate perturbation in the Arctic."
"57206526682;","The parameterization of shortwave and longwave radiative fluxes for use in zonally averaged climate models",1996,"10.1175/1520-0442(1996)009<0439:TPOSAL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029729278&doi=10.1175%2f1520-0442%281996%29009%3c0439%3aTPOSAL%3e2.0.CO%3b2&partnerID=40&md5=9a152a414475ccef056c42a0c4af0c51","The shortwave and longwave fluxes at the top of the atmosphere (TOA) and at the surface are parameterized in terms of solar constant, solar zenith angle, cloud parameters (amount, optical depth, height, and emissivity), surface albedo, surface air temperature, surface temperature, and atmospheric CO2 concentration. Detailed radiative models are used to calculate up- and downward radiative fluxes at TOA and at the surface with input from standard vertical atmospheric profiles of temperature, water vapor, and ozone. Expressions for clear-sky and completely overcast conditions are presented. It is shown that there is reasonably good agreement between the radiative fluxes calculated with this parameterization, with the detailed radiation models and with standard radiation codes (ICRCCM). Furthermore, it is shown that the parameterization is able to produce with reasonable accuracy several aspects of the latitudinally and seasonally varying, zonally averaged shortwave and longwave radiative fluxes at TOA and at the surface. The effect of clouds on the radiative fluxes as calculated with the parameterization compares reasonably well with observations, which is an important aspect for climate modeling studies. The radiation parameterization presented here is particularly useful in zonal average climate models (such as energy balance climate models) that treat the atmosphere as one bulk layer, since it is computationally efficient."
"7401823436;7405408411;8204540500;7202866440;7203015939;","Climatic effects of biomass burning",1996,"10.1016/S0266-9838(96)00039-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030300286&doi=10.1016%2fS0266-9838%2896%2900039-1&partnerID=40&md5=bed808c398283d1d32c675f4857ca4e2","We have made a series of general circulation model (GCM) and chemical transport model (CTM) simulations to examine further the consequences of biomass burning. We take a three-pronged approach to this study; (1) examine only the direct short-wave forcing of the smoke clouds by imposing smoke 'clouds' in the model, (2) examine the indirect effect of biomass smoke by allowing the biomass smoke to modify the optical properties of existing clouds, reducing the effective (mass) droplet radius, and (3) examine the downstream effect by advecting biomass smoke using semi-Lagrangian transport in the GCM. Preliminary results from the GCM simulations suggest strong local coolings (2-4°C or more) where biomass burning occurs with somewhat reduced regional coolings. Initial results of the transport of smoke by the Australian National University CTM (ANU-CTM) show the biomass smoke to remain fairly localized with the advection of smoke extending the effects downwind. Copyright © 1996 Elsevier Science Ltd."
"6506983183;6602271520;6602107874;7202845097;7006211890;","The retrieval of cloud microphysical properties using satellite measurements and an in situ database",1996,"10.1007/s00585-996-0098-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2842574783&doi=10.1007%2fs00585-996-0098-3&partnerID=40&md5=df90845a4fb1035b44cf0c3e65d00d93","By combining AVHRR data from the NOAA satellites with information from a database of in situ measurements, large-scale maps can be generated of the microphysical parameters most immediately significant for the modelling of global circulation and climate. From the satellite data, the clouds can be classified into cumuliform, stratiform and cirrus classes and then into further sub-classes by cloud top temperature. At the same time a database of in situ measurements made by research aircraft is classified into the same sub-classes and a statistical analysis is used to derive relationships between the sub-classes and the cloud microphysical properties. These two analyses are then linked to give estimates of the microphysical properties of the satellite observed clouds. Examples are given of the application of this technique to derive maps of the probability of occurrence of precipitating clouds and of precipitating water content derived from a case study within the International Cirrus Experiment (ICE) held in 1989 over the North Sea."
"6603468473;7006393267;","Remote sensing of cloud optical properties from ground-based measurements of transmittance: A feasibility study",1996,"10.1175/1520-0450(1996)035<2011:RSOCOP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030428119&doi=10.1175%2f1520-0450%281996%29035%3c2011%3aRSOCOP%3e2.0.CO%3b2&partnerID=40&md5=2b866f2274afa846edb21901561df621","The authors present a retrieval technique for the inference of cloud optical depth from data obtained by a ground-based multichannel radiometer for use in climate-related studies. The basic steps of the analysis procedure are considered, including accurate calculations of the atmosphere and cloud properties. An approach is described that uses observed and model-simulated transmittances rather than irradiances and that does not depend on an absolute calibration of the instrument. This approach, which specifically deals with the transmittances, also offers substantial computational advantages. The resulting algorithm is applied (but not limited) to the measurements of incoming solar irradiance by a particular ground-based instrument, the so-called Multi-Filter Rotating Shadowband Radiometer (MFRSR). Sample results of inferred cloud optical depth obtained from MFRSR measurements in Fairbanks, Alaska, are presented."
"8348260100;7006423931;7006630889;8348260700;56222822400;","Volcanic aerosols and interannual variation of high clouds",1996,"10.1029/96GL02372","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030235406&doi=10.1029%2f96GL02372&partnerID=40&md5=02368aa3f429e7c6694a40c1ff407266","Interannual variability of high-level cloudiness (HC) is examined using global outgoing longwave radiation (OLR). Variations of HC are analyzed versus a measure of global stratospheric aerosol amount and an El Nino index. Volcanic aerosols are apparently associated with widespread increases of up to 10% in an OLR-based HC index. The most significant effects occurred in middle latitudes and persisted for several years after major eruptions. El Nino is found to be associated with decreased cloud activity in the subtropics. This study suggests that volcanic aerosols can significantly modify global cloudiness, and that stratospheric aerosol loading can be an important variable controlling the interannual variations of high level clouds and climate. Copyright 1996 by the American Geophysical Union."
"7409189983;7005533663;7004201998;","Impacts of tropical deforestation. Part I: Process analysis of local climatic change",1996,"10.1175/1520-0442(1996)009<1497:IOTDPI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030437998&doi=10.1175%2f1520-0442%281996%29009%3c1497%3aIOTDPI%3e2.0.CO%3b2&partnerID=40&md5=ef42aad6f4eea4f6a70e9b1d1445d408","The potential impacts of deforestation in the humid Tropics are examined using a version of the National Center for Atmospheric Research's CCM1 coupled with the Biosphere-Atmosphere Transfer Scheme package. Tropical deforestation in South America, Africa, and Southeast Asia is studied using the results from an 11-yr deforestation experiment and a 25-yr control integration. It is found that the local-scale impact (here defined as within the area deforested) varies greatly between the three deforested regions due to the differing controls on the local atmospheric circulation: the Southeast Asian monsoon is much less sensitive to deforestation than the low-level flow over South America. The analysis of the changes in cloud radiative forcing suggests that reduction in cloud amount can significantly mitigate the imposed increases in surface albedo. The importance of water recycling by the forest canopy is stressed in the simulation of local precipitation changes. Correlation analysis of the changes resulting from the deforestation has been used to determine the nature of the processes that follow from the removal of the forest canopy and to suggest the important processes. The role of large-scale dynamics is explored in a companion paper."
"56332035300;7201859626;7003673986;","Global remnant cloud contamination in the along-track scanning radiometer data: Source and removal",1996,"10.1029/96JC00799","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029960669&doi=10.1029%2f96JC00799&partnerID=40&md5=9bb96f62f423a6a0f2b40b0eb4d31e9a","Validation studies indicate that in cloud free conditions the along-track scanning radiometer (ATSR) on the ERS 1 satellite is measuring global sea surface temperature (SST) to a point relative precision of better than 0.3°C. However, recent reports show that the presence of nighttime remnant cloud contamination is affecting ATSR SST precision in certain geographical areas. We modify the filtering scheme described by Jones et al. [1996] for removing remnant cloudiness in ATSR 0.5° spatially averaged sea surface temperature (ASST) data from the South Atlantic and apply this scheme to global ASST data (version 500) for the whole of 1992, 1993, and 1994. We find that globally 4.65% of the ASST data is cloud contaminated and that remnant cloud removal substantially reduces differences between day and night SST signals. The cloud contamination is seasonal and is linked to the occurrence of marine stratiform (fog, stratus, and stratocumulus) cloud types. Such cloud is low-lying and uniform and thus difficult to detect with conventional cloud-clearing techniques. Our effective global removal of remnant cloudiness will improve the accuracy of the ASST data and thus benefit the use of the ATSR in the early detection of climate change. Copyright 1996 by the American Geophysical Union."
"6602831555;6602627241;7004194999;55684491100;","Simulating the global atmospheric response to aircraft water vapour emissions and contrails: A first approach using a GCM",1996,"10.1007/s00585-996-0941-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000815519&doi=10.1007%2fs00585-996-0941-6&partnerID=40&md5=cf8a2fb317be990e1a3c274e2f8092d5","The effect of contrails and aircraft water vapour emissions on global climate is studied by means of a general circulation model (GCM). In a first approach water vapour emissions and mean contrail coverage within the main flight routes are prescribed according to current observations in a simplified manner. A hierarchic experiment strategy with gradual increase of the forcing is applied to identify the resulting climate signals. The water vapour increase to be expected from air traffic is too small to force a detectable radiative or climatic response. The sensitivity of the model climate to the occurrence of contrails appears to be higher. For mid-latitude summer conditions, the high cloud increase experiments show a consistent temperature response pattern. However, its magnitude is statistically significant only for a mean contrail coverage exceeding present-day amounts. Moreover, the magnitude of the contrail climate signal is highly sensitive to the details of the experimental setup due to several non-linearities of the cloud-radiative interaction. Hence, the prescription of contrails in the GCM has to be as careful as possible for an optimal treatment of the problem. Respective recommendations are given."
"6603371044;6602592755;7103211168;","The climatology of parameterized physical processes in the GEOS-1 GCM and their impact on the GEOS-1 data assimilation system",1996,"10.1175/1520-0442(1996)009<0764:TCOPPP>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029730012&doi=10.1175%2f1520-0442%281996%29009%3c0764%3aTCOPPP%3e2.0.CO%3b2&partnerID=40&md5=0719e8a420e47f276e326b225ddde67d","The Goddard Earth Observing System (GEOS) General Circulation Model (GCM) is part of the GEOS Data Assimilation System (DAS), which is being developed at the Goddard Data Assimilation Office for the production of climate datasets. This study examines Version 1 of the GEOS GCM by evaluating the quality of the fields that relate most closely to the GCM physical parameterizations and examines the impact of the GCM climate errors on the climate of the DAS assimilated fields. The climate characteristics are evaluated using independent satellite and ground-based data for comparison. The GEOS-I GCM shows reasonably good agreement with available observations in terms of general global distribution and seasonal cycles. The major biases or systematic errors are a tendency toward a dry tropical atmosphere and an inadequate cloud radiative impact in the extratropics. Other systematic errors are a generally wet subtropical atmosphere, slightly excess precipitation over the continents, and excess cloud radiative effects over the Tropics. There is also an underestimation of surface sensible and latent heat fluxes over the area of maximum flux. The DAS climate characteristics, in general, show better agreement with available observations than the GCM. Four distinct ways that the GCM impacts the DAS have been identified, ranging from a DAS climate with little or no impact from the GCM bias to a DAS climate with a greater bias than the GCM due to a spurious feedback between the GCM and the input data."
"7203019582;","Heat island intensity with different meteorological conditions in a medium-sized town: Szeged, Hungary",1996,"10.1007/BF00865157","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030436407&doi=10.1007%2fBF00865157&partnerID=40&md5=25bc1db20729c21ac4867f4be593ee06","An analysis of the effects of the town Szeged, Hungary, on minimum temperatures between 1978 and 1980 is presented. The characteristics of the urban heat island effect were examined by revelation of the relationships between heat island intensity and macrosynoptic types, cloudiness, wind speed as well as the combination of cloud amount and wind speed. Anticyclonic weather situations little or no cloud coverage, and calm or slight wind were favourable for a strong development of the heat island effect. In the case of extreme heat islands the domination of anticyclonic weather types was almost absolute."
"7007108728;7202659684;","Relationships between cloud type and amount, precipitation, and surface temperature in the Mackenzie River valley-Beaufort Sea area",1996,"10.1175/1520-0442(1996)009<1921:RBCTAA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030485456&doi=10.1175%2f1520-0442%281996%29009%3c1921%3aRBCTAA%3e2.0.CO%3b2&partnerID=40&md5=631cfd651d79926dbbbbfe3597bede5b","Hourly data from climatological stations in the Mackenzie River valley - Beaufort Sea area of northern Canada have been examined to determine the relationships between cloud type and amount, precipitation, and surface temperatures. During all seasons, stratocumulus is the dominant cloud type for both precipitating and nonprecipitating hours. More stratocumulus cloud occurs when temperatures are wanner in the winter and colder in the summer. Similarly, precipitation occurs more frequently and the total amount is greater when temperatures are wanner in the winter and colder in the summer. Overcast skies are dominant for all seasons when precipitation is falling. During the winter, during nonprecipitating hours, clear skies are most frequent. During the summer, during nonprecipitating hours, some cloud is usually present. Surface temperatures are warmer in the winter with overcast skies and warmer in the summer with clear skies. An attempt has been made to quantify the above conclusions so that comparisons can be made with global climate models."
"7006211890;6602271520;7202845097;","The reliability of the PMS FSSP in the presence of small ice crystals",1996,"10.1175/1520-0426(1996)013<1300:TROTPF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001021030&doi=10.1175%2f1520-0426%281996%29013%3c1300%3aTROTPF%3e2.0.CO%3b2&partnerID=40&md5=b8100f1995a95cae3f4c4da1d8718486","The performance of measurement systems for small ice crystals is an important issue because of the need to characterize cirrus cloud microphysics for climate research. In a cloud formed of small quasi-spherical ice particles, as found in recently formed aircraft contrails, the PMS FSSP probe gives reliable measurements consistent with other probes. This is in contrast to the expectation, based on earlier work by others, that the FSSP measurements are unreliable when ice is present in the cloud. In natural cirrus on the other hand, where there are irregular large ice particles, the FSSP indeed gives the exaggerated response reported earlier. Here simple criteria by which the presence of spherically shaped small ice particles can be recognized are proposed. These criteria provide a useful indication of the occasions in ice clouds when FSSP measurements can be relied on."
"7203054240;16197778800;7202155374;","Response of tropical clouds to the interannual variation of sea surface temperature",1996,"10.1175/1520-0442(1996)009<0616:ROTCTT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029730933&doi=10.1175%2f1520-0442%281996%29009%3c0616%3aROTCTT%3e2.0.CO%3b2&partnerID=40&md5=b78e315451e984c25ae613be9e78759e","Connections between the large-scale interannual variations of clouds, deep convection, atmospheric winds, vertical thermodynamic structure, and SSTs over global tropical oceans are examined over the period July 1983-December 1990. The SST warming associated with El Niño had a significant impact on the global tropical cloud field, although the warming itself was confined to the equatorial central and eastern Pacific. Extensive variations of the total cloud field occurred in the northeastern Indian, western and central Pacific, and western Atlantic Oceans. The changes of high and middle clouds dominated the total cloud variation in these regions. Total cloud variation was relatively weak in the eastern Pacific and the Atlantic because of the cancellation between the changes of high and low clouds. The variation of low clouds dominated the total cloud change in those areas. The destabilization of the lapse rate between 900 and 750 mb was more important for enhancing convective instability than was the change of local SSTs in the equatorial central Pacific during the 1987 El Niño. This destabilization is associated with anomalous rising motion in that region. As a result, convection and high and middle clouds increased in the equatorial central Pacific. In the subtropical Pacific, both the change of lapse rate between 900 and 750 mb associated with anomalous subsidence and the decrease of boundary-layer buoyancy due to a decrease of temperature and moisture played an important role in enhancing convective stability. Consequently, convection, as well as high and middle clouds, decreased in these areas. The change of low clouds in the equatoral and southeastern Atlantic was correlated to both local SSTs and the SST changes in the equatorial eastern Pacific. In this area, the increase of low clouds was consistent with the sharper inversion during the 1987 El Niño. The strengthening of the inversion was not caused by a local SST change, although the local SST change appeared to be correlated to the change of low clouds. The coherence between clouds and SST tendency shows that SST tendency leads cloud variation in the equatorial Pacific. Thus, the change of clouds does not dominate the sign of SST tendency even though the cloud change was maximum during the 1987 El Niño. In some areas of the Indian, subtropical Pacific, and North Atlantic Oceans, cloud change leads SST tendency. Cloud change might affect SST tendency in these regions."
"7003554893;7103119050;7003341040;6603873829;7004061048;7202208382;6701341222;57203504470;","Modeling a stratocumulus-topped PBL: Intercomparison among different one-dimensional codes and with large eddy simulation",1996,"10.1175/1520-0477(1996)077<2033:MASTPI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030405188&doi=10.1175%2f1520-0477%281996%29077%3c2033%3aMASTPI%3e2.0.CO%3b2&partnerID=40&md5=4c510cbfbd1d72c78017ef9c27af1726","Several one-dimensional (1D) cloud/turbulence ensemble modeling results of an idealized nighttime marine stratocumulus case are compared to large eddy simulation (LES). This type of model intercomparison was one of the objects of the first Global Energy and Water Cycle Experiment Cloud System Study boundary layer modeling workshop held at the National Center for Atmospheric Research on 16-18 August 1994. Presented are results obtained with different 1D models, ranging from bulk models (including only one or two vertical layers) to various types (first order to third order) of multilayer turbulence closure models. The 1D results fall within the scatter of the LES results. It is shown that 1D models can reasonably represent the main features (cloud water content, cloud fraction, and some turbulence statistics) of a well-mixed stratocumulus-topped boundary layer. Also addressed is the question of what model complexity is necessary and can be afforded for a reasonable representation of stratocumulus clouds in mesoscale or global-scale operational models. Bulk models seem to be more appropriate for climate studies, whereas a multilayer turbulence scheme is best suited in mesoscale models having at least 100- to 200-m vertical resolution inside the boundary layer."
"7407104838;7004034323;","Predicting cloud-droplet effective radius and indirect sulphate aerosol forcing using a general circulation model",1996,"10.1002/qj.49712253506","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030422589&doi=10.1002%2fqj.49712253506&partnerID=40&md5=86a00b40405a9000ba643734e5b10f8f","Various methods for predicting cloud-droplet effective radius in the Hadley Centre general circulation model are compared with aircraft and satellite retrievals, and are used to estimate the indirect radiative forcing by anthropogenic sulphate aerosols since the beginning of the industrial era. The effects both of different parametrization approaches and of different input sulphate data sets are examined; however, there is no clear evidence to prefer either of the two sulphate data sets used in the study. Two of the parametrizations generate distributions of presentday effective radius which are similar to each other and compare favourably with observations, yet provide very different estimates of the indirect effect, ranging from -0.5 to -1.5 W m-2 in the global annual mean. A sensitivity experiment in which it is assumed that droplet concentrations are not determined by sulphate concentrations in continental air reduces this global-mean forcing to -0.3 to -0.8 W m-2. This sensitivity demonstrates the need for a much better understanding of the link between sulphate aerosol mass concentrations, cloud condensation nuclei, and cloud-droplet number concentrations."
"57193920163;7004034323;","Studies with a flexible new radiation code. I: Choosing a configuration for a large-scale model",1996,"10.1256/smsqj.53106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030470929&doi=10.1256%2fsmsqj.53106&partnerID=40&md5=2cbefc440770c19066e3c1d01dc9bd11","A comprehensive new radiation code based on the two-stream equations in both the long-wave and short-wave spectral regions is described. The spectral resolution of the code is variable, enabling it to be used in a wide range of applications. Because of its flexibility, the code is well-suited to the investigation of the sensitivity of radiative calculations to changes in the way in which physical processes are parametrized. The gaseous transmission data are derived from a line-by-line model. Particular attention is directed towards the treatment of the water vapour continuum, the overlap between gases, and the sensitivity to changing the carbon dioxide concentrations. The performance of the code is examined both at high spectral resolution and in a lower-resolution configuration designed for the UK Meteorological Office Unified Forecast/Climate Model (UM). Particularly for use in the UM, the code must be shown to perform satisfactorily across the whole range of atmospheric conditions. Comparisons are therefore made with reference calculations in both the long-wave and the short-wave, in clear and cloudy skies, and the accuracy with which various processes may be represented is studied. For the cloudy calculations in the short-wave, a new method is presented for deriving the single-scattering properties in broad bands, based on the analytic expression for the reflectivity of an optically thick cloud. This minimizes the errors in calculating the short-wave radiative properties of water clouds when the spectral resolution is reduced to that designed for the UM. In contrast, for ice clouds the errors are minimized by deriving the single-scattering properties using linear averaging, as appropriate for optically thin clouds. In the long-wave, the vertical distribution of the radiative heating in cirrus clouds is examined at high spectral resolution. The effect of scattering of long-wave radiation, usually ignored in large-scale models, is examined in some detail and is explained using a simple model. Taking all these studies into account, it is concluded that the configuration designed for the UM retains the generality of the code, without significantly compromising the overall accuracy."
"6505791563;57214416067;","Meteorological research applications of MM-wave radar",1996,"10.1007/BF01032003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030554173&doi=10.1007%2fBF01032003&partnerID=40&md5=d9916f74e9d1e6b8af61ee67ccaa38e0","MM-wave radar has now been developed well beyond that of simply providing qualitative information about the presence or location of clouds. Uncertainty about cloud properties leading to gross errors in climate model results has provided the impetus to develop mm-wave radars into reliable, quantitative tools for studying clouds. Besides depicting the small-scale (a few tens of meters) features of tenuous cirrus and low level stratus clouds, the 3 mm and 8 mm wavelength radars described here can examine the physical structure, dynamics and small-scale turbulence of clouds when used alone. Polarization capability of these radars is now generating new information about the deformity of cloud particles needed for calculations of radiation budgets of clouds. When used with other sensors such as lidar or radiometers, additional cloud microphysical information can be retrieved. We discuss here two different ways to calculate ice mass content profiles from radar/lidar data and from radar/IR radiometer data. Mm-wave radar is most suited for these calculations because of complications introduced by 1) Bragg (refractivity) scatter, 2) the lower resolution, and 3) ground clutter effects at longer wavelengths. Combining radar and microwave radiometer data is shown to provide liquid water profiles in warm marine stratus clouds. The small size and weight of mm-wave radars make them particularly suitable for use on aircraft and satellite platforms and we show recent results from an airborne system to make that point. The technology has now advanced to the point where unattended, vertically-pointing, Doppler mm-wave radars will soon be commonly used in research applications."
"57201201895;56853406500;","Sensitivity of shallow convective precipitation induced by land surface heterogeneities to dynamical and cloud microphysical parameters",1996,"10.1029/95JD02167","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030466549&doi=10.1029%2f95JD02167&partnerID=40&md5=7348221fb70ff16b21563bce5815f3f9","To parameterize shallow convective clouds and precipitation induced by land surface processes in large-scale atmospheric models (e.g., global climate models and weather forecast models), it is primordial to identify the atmospheric variables and cloud microphysical parameters which have a predominant impact on the development and formation of this type of clouds. For this purpose a sensitivity analysis of the various parameters and processes involved in the development and formation of this type of clouds and precipitation was performed with the Fourier amplitude sensitivity test (FAST). This test determines the relative contribution of the distribution of individual input parameters, assuming that their exact value is unknown, to the variance of the model output. By simultaneously varying all parameters according to their individual probability density function (PDF), the number of computations needed is very much reduced. Assuming various PDFs of cloud microphysical characteristics under a broad range of atmospheric conditions, this analysis demonstrated that given an appropriate atmospheric water content, vertical velocity and air temperature are the dominant atmospheric factor in shallow convective precipitation. This emphasizes the need to correctly calculate the spatial distribution of land surface heat fluxes, which affect the development of microscale and mesoscale turbulence in the atmospheric planetary boundary layer. The uncertainty in estimating cloud droplet concentration, pristine ice concentration, mass coefficient, collision efficiency, terminal velocity, snow crystals diameter, and aggregates diameter can affect quite significantly, one way or the other, the mixing ratio of the various water particles simulated with the cloud microphysics scheme. The relative importance of some of these parameters is very much dependent upon temperature and vertical velocity. Copyright 1996 by the American Geophysical Union."
"6602693652;7004462114;7006415284;7006595513;7005228425;","Influence of fog and haze events on submicron particle size distributions in the Po Valley region of Northern Italy",1996,"10.1016/0021-8502(96)00123-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030233158&doi=10.1016%2f0021-8502%2896%2900123-1&partnerID=40&md5=3a01da3b0b3b6523b5011f73bccf6e2c","The inter-relation between atmospheric particles and cloud droplets was one focus of the CHEMDROP campaign in the highly polluted Po Valley region of Northern Italy, conducted on November 1994. Aerosol measurements at the field station S. Pietro Capofiune provided data on the size distribution of particles during periods of thick haze or fog, and covered a particle size range from 3 to 850 nanometers (nm). Particle size distribution data showed the existence of three modes in the submicron aerosol, namely, the ultrafine, Aitken, and accumulation modes, having geometric mean diameters (GMD) of 17 nm, 120 nm, and 250-425 nm, respectively."
"7007152721;6506049481;","Urban effects on convective precipitation in Mexico City",1996,"10.1016/1352-2310(96)00041-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030251173&doi=10.1016%2f1352-2310%2896%2900041-6&partnerID=40&md5=cd541a7d254cf16b35d4995cc5ac396f","This paper reports on urban-related convective precipitation anomalies in a tropical city. Wet season (May-October) rainfall for an urban site (Tacubaya) shows a significant trend for the period 1941-1985 suggesting an urban effect that has been increasing as the city grew. On the other hand, rainfall at a suburban (upwind) station apparently unaffected by urbanization, has remained unchanged. Analysis of historical records of hourly precipitation for an urban station shows that the frequency of intense (&gt; 20 mm h-1) rain showers has increased in recent decades. Using a network of automatic rainfall stations, areal distribution of 24 h isoyets show a series of maxima within the urban perimeter which may be associated to the heat island phenomenon. Isochrones of the beginning of rain are used to estimate direction and speed of movement of the rain cloud cells. The daytime heat island seems to be associated with the intensification of rain showers."
"7003679645;","Non-dimensional measures of climate model performance",1996,"10.1002/(SICI)1097-0088(199604)16:4<379::AID-JOC18>3.0.CO;2-U","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030462665&doi=10.1002%2f%28SICI%291097-0088%28199604%2916%3a4%3c379%3a%3aAID-JOC18%3e3.0.CO%3b2-U&partnerID=40&md5=8b74fdd14ab091dff9902e02d9b17a0c","The characteristics of several non-dimensional measures of skill, which can be readily used to quantify the accuracy of simulated climatological fields, are examined. The correlation coefficient, the 'SITESI' measure, and two forms of Willmott's 'index of agreement' are compared with Mielke's measure of agreement. After certain transformations, the measures converge similarly to unity, for small errors. Fields simulated by the CSIRO9 general circulation model are used to illustrate the behaviour of the measures. Although all the measures can be useful, it is shown that the transformation M of the mean square ρ, where M=2 arcsin(ρ)/π, is especially practical. In comparing the skill of several climate models in simulating the global distribution of seasonal mean sea-level pressure, M ranged from 0.02 to 0.75. In comparing the skill of CSIRO9 in simulating various climatological quantities, M values ranged from 0.23 for cloud cover to 0.85 for surface air temperature. In comparing present and doubled CO2 climates simulated by CSIRO9, the quantity with the largest change, relative to its spatial variation, is the water vapour column (M=0.67) and that with the smallest change is sea-level pressure (M=0.90)."
"7005956183;7004563885;35619149500;6603667908;","Estimation of moisture in the atmosphere and in the ground from satellite data",1996,"10.1016/S0273-1177(96)90975-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029753754&doi=10.1016%2fS0273-1177%2896%2990975-8&partnerID=40&md5=604d2ef94cd26a779e5c347a33ea6b3c","There is a manifold of non-linear interactions in our climate system, where water in all of its three phases plays a dominant role. Water transports energy and many pollutants; water in the atmosphere modifies very effectively the energy transports by radiation. Therefore we must know quite accurately the energy and water transports in our climate system. Numerical models for weather forecast, for climate simulations, for estimate of transports of additional materials - in particular pollutants - and simulations of the impact of climate variations must be capable to simulate such transports. These goals are well defined within the scope of the GEWEX, Global Energy and Water Cycle Experiment, a subprogramme of the World Climate Research Programme. GEWEX has a major observational component, to measure and monitor with space-based instruments the atmospheric water vapour in all layers of the troposphere, the cloud water contents and the partition of its liquid and solid phases, the precipitation over continents and oceans - also in form of snow - and also various surface characteristics, which allow to estimate the evaporation and evapotranspiration of water. -from Editors"
"6603120830;7005067383;7404243086;","Influence of crystal shapes on radiative fluxes in visible wavelength: Ice crystals randomly oriented in space",1996,"10.1007/s00585-996-0837-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0008203684&doi=10.1007%2fs00585-996-0837-5&partnerID=40&md5=8172754e50a9b007e27e6e7008eb5d0e","Radiative properties of cirrus clouds are one of the major unsolved problems in climate studies and global radiation budget. These clouds are generally composed of various ice-crystal shapes, so we tried to evaluate effects of the ice-crystal shape on radiative fluxes. We calculated radiative fluxes of cirrus clouds with a constant geometrical depth, composed of ice crystals with different shapes (hexagonal columns, bullets, bullet-rosettes), sizes and various concentrations. We considered ice particles randomly oriented in space (3D case) and their scattering phase functions were calculated by a ray-tracing method. We calculated radiative fluxes for cirrus layers for different microphysical characteristics by using a discrete-ordinate radiative code. Results showed that the foremost effect of the ice-crystal shape on radiative properties of cirrus clouds was that on the optical thickness, while the variation of the scattering phase function with the ice shape remained less than 3% for our computations. The ice-water content may be a better choice to parameterize the optical properties of cirrus, but the shape effect must be included."
"7003679645;7006577693;","Influences on surface energy fluxes in simulated present and doubled CO2 climates",1996,"10.1007/BF00231107","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030477656&doi=10.1007%2fBF00231107&partnerID=40&md5=90cfc9f68fa60dc59e6ef93ab54c35af","The surface energy fluxes simulated by the CSIRO9 Mark 1 GCM for present and doubled CO2 conditions are analyzed. On the global scale the climatological flux fields are similar to those from four GCMs studied previously. A diagnostic calculation is used to provide estimates of the radiative forcing by the GCM atmosphere. For 1 × CO2, in the global and annual mean, cloud produces a net cooling at the surface of 31 W m-2. The clear-sky longwave surface greenhouse effect is 311 W m-2, while the corresponding shortwave term is -79 W m-2. As for the other GCM results, the CSIRO9 ΔCO2 surface warming (global mean 4.8°C) is closely related to the increased downward longwave radiation (LW↓). Global mean net cloud forcing changes little. The contrast in warming between land and ocean, largely due to the increase in evaporative cooling (E) over ocean, is highlighted. In order to further the understanding of influences on the fluxes, simple physically based linear models are developed using multiple regression. Applied to both 1 × CO2 and ΔCO2 December-February mean tropical fields from CSIRO9, the linear models quite accurately (3-5 W m-2 for 1 × CO2 and 2-3 W m-2 for ΔCO2) relate LW↓ and net shortwave radiation to temperature, surface albedo, the water vapor column, and cloud. The linear models provide alternative estimates of radiative forcing terms to those from the diagnostic calculation. Tropical mean cloud forcings are compared. Over land, E is well correlated with soil moisture, and sensible heat with air-surface temperature difference. However an attempt to relate the spatial variation of LW↑ within the tropics to that of the non-flux fields had little success. Regional changes in surface temperature are not linearly related to. for instance, changes in cloud or soil moisture."
"7004884101;7406215388;7005490049;","Application of the 915 MHz profiler for diagnosing and classifying tropical precipitating cloud systems",1996,"10.1007/BF01032005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030535954&doi=10.1007%2fBF01032005&partnerID=40&md5=3e915abd7038f922c5a0ed53929165c9","The NOAA Aeronomy Laboratory has developed a 915 MHz lower tropospheric wind profiler designed primarily for measuring wind in the planetary boundary layer of the tropics. In recent years the profiler has been used in many field programs worldwide. The profiler is being deployed by the Aeronomy Laboratory at several locations in the tropics to provide long-term measurements for the Tropical Ocean Global Atmosphere (TOGA) program and the Global Ocean Atmosphere Land Surface (GOALS) program. In the absence of precipitating cloud systems the profiler observes winds routinely up to altitudes of 3 to 6 km in the tropics depending primarily on humidity. In the presence of precipitating cloud systems, however, the profiler height coverage is substantially increased due to the presence of hydrometeors to which the profiler is sensitive at its wavelength of 33 cm. In this paper we examine the application of the 915 MHz profiler to the diagnosis and classification of precipitating cloud systems in the tropics. Preliminary results from Christmas Island confirm that at least half of tropical rainfall is stratiform in nature being associated with mesoscale convective systems. The 915 MHz profiler provides a means for the development of a climatology of tropical precipitating cloud systems. Such a climatology is needed to specify diabatic heating rates in large-scale numerical weather prediction and climate models. It should also help develop improved rain retrieval algorithms from satellite observations."
"7005965757;7006518289;","High-latitude climate change in a global coupled oceanatmosphere-sea ice model with increased atmospheric CO2",1996,"10.1029/96JD00505","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029854101&doi=10.1029%2f96JD00505&partnerID=40&md5=d65998cdd517a37afbe129f266cac817","A global atmospheric general circulation model (GCM) coupled to a global 1-degree, 20-level ocean GCM with dynamic and thermodynamic sea ice is integrated with CO2 increasing at 1% per year compounded for 75 years (CO2 doubles at about year 70). Flux correction is not used in the experiment. The increase of globally averaged surface air temperature at the time of CO2 doubling is 3.8°C. The warm subsurface Atlantic layer at intermediate depths in the Arctic is maintained mainly by the sinking and intrusion of water from the West Spitsbergen Current in the model and the observations. With increased CO2 in the model, the warmer surface waters are intruded into the upper portion of the Atlantic layer producing an anomalous warming in the model at depths between 200 and 400 m. This resembles an anomalous warm layer near those depths recently observed in the Arctic. As the climate warms and sea ice retreats, low clouds increase over the newly exposed water. Yet the consequent increase of cloud albedo over these regions is more than compensated for by the decrease of surface albedo due to the melting of sea ice. This produces a net decrease of planetary albedo in the Arctic that contributes to a strong ice-albedo feedback and the comparatively high sensitivity of the model. Copyright 1996 by the American Geophysical Union."
"7407273403;7201782051;7201547576;","Tropical sea surface temperatures and the Earth's orbital eccentricity cycles",1996,"10.1029/96GL02923","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030291954&doi=10.1029%2f96GL02923&partnerID=40&md5=f125d9eea7b0dd42a28920892e7f73e6","The tropical oceanic warm pools are climatologically important regions because their sea surface temperatures (SSTs) are positively related to atmospheric greenhouse effect and the cumulonimbus-cirrus cloud anvil. Such a warm pool is also present in the central tropical Indian Ocean. Paleo-SSTs estimated by the radiolarian transfer functions for the last ∼200-1400 kiloyears (ka) in a deep-sea sediment core from this warm pool fluctuated within 2.75°C (26.14-28.89°C) around the threshold temperature (27°C) for the super greenhouse effect. It is possible that this SST variation might have led to the corresponding fluctuation in the greenhouse effect and the cirrus cloud anvil in the geological past. These paleo-SSTs also exhibited cyclicities at ∼100- and ∼400-ka corresponding to the Earth's orbital eccentricity cycles. Results, therefore imply that the tropical Indian Ocean warm pool persisted during the Quaternary and the paleo-SSTs fluctuating at the orbital eccentricity frequencies might have modulated the intensity of greenhouse effect. Copyright 1996 by the American Geophysical Union."
"55207447000;","The Whitehouse effect - Shortwave radiative forcing of climate by anthropogenic aerosols: An overview",1996,"10.1016/0021-8502(95)00533-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030130758&doi=10.1016%2f0021-8502%2895%2900533-1&partnerID=40&md5=e196549ef267d7e8554fee1ac1f530a4","Loadings of tropospheric aerosols have increased substantially over the past 150 yr as a consequence of industrial activities. These aerosols enhance reflection of solar radiation by the Earth-atmosphere system both directly, by scattering light in clear air and, indirectly, by increasing the reflectivity of clouds. The magnitude of the resultant decrease in absorption of solar radiation is estimated to be comparable on global average to the enhancement in infrared forcing at the tropopause due to increases in concentrations of CO2 and other greenhouse gases over the same time period. Estimates of the aerosol shortwave forcing are quite uncertain, by more than a factor of two about the current best estimates. This article reviews the atmospheric chemistry and microphysical processes that govern the loading and light scattering properties of the aerosol particles responsible for the direct effect and delineates the basis for the present estimates of the magnitude and uncertainty in the resultant radiative forcing. The principal sources of uncertainty are in the loading of anthropogenic aerosols, which is highly variable spatially and temporally because of the relatively short residence time of these aerosols (ca. 1 week) and the episodic removal in precipitation, and in the dependence of light scattering on particle size, and in turn on relative humidity. Uncertainty in aerosol forcing is the greatest source of uncertainty in radiative forcing of climate over the industrial period. At the high end of the uncertainty range, the aerosol forcing is comparable to the anthropogenic greenhouse forcing, and substantially greater in industrialized regions. Even at the low end of the range, the aerosol forcing cannot be neglected in considerations of influences on climate over the industrial period. This uncertainty greatly limits the ability to draw empirical inferences of climate sensitivity to radiative forcing.Loadings of tropospheric aerosols have increased substantially over the past 150 yr as a consequence of industrial activities. These aerosols enhance reflection of solar radiation by the Earth-atmosphere system both directly, by scattering light in clear air and, indirectly, by increasing the reflectivity of clouds. The magnitude of the resultant decrease in absorption of solar radiation is estimated to be comparable on global average to the enhancement in infrared forcing at the tropopause due to increases in concentrations of CO2 and other greenhouse gases over the same time period. Estimates of the aerosol shortwave forcing are quite uncertain, by more than a factor of two about the current best estimates. This article reviews the atmospheric chemistry and micro-physical processes that govern the loading and light scattering properties of the aerosol particles responsible for the direct effect and delineates the basis for the present estimates of the magnitude and uncertainty in the resultant radiative forcing. The principal sources of uncertainty are in the loading of anthropogenic aerosols, which is highly variable spatially and temporally because of the relatively short residence time of these aerosols (ca. 1 week) and the episodic removal in precipitation, and in the dependence of light scattering on particle size, and in turn on relative humidity. Uncertainty in aerosol forcing is the greatest source of uncertainty in radiative forcing of climate over the industrial period. At the high end of the uncertainty range, the aerosol forcing is comparable to the anthropogenic greenhouse forcing, and substantially greater in industrialized regions. Even at the low end of the range, the aerosol forcing cannot be neglected in considerations of influences on climate over the industrial period. This uncertainty greatly limits the ability to draw empirical inferences of climate sensitivity to radiative forcing."
"7003666669;7103023423;6602264002;","Simulation of the Great Plains low-level jet and associated clouds by general circulation models",1996,"10.1175/1520-0493(1996)124<1388:SOTGPL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0006461436&doi=10.1175%2f1520-0493%281996%29124%3c1388%3aSOTGPL%3e2.0.CO%3b2&partnerID=40&md5=26946ed16eb664f17abc7d6597e60af9","The low-level jet frequently observed in the Great Plains of the United States forms preferentially at night and apparently influences the timing of thunderstorms in the region. The authors have found that both the European Centre for Medium-Range Weather Forecasts general circulation model and the National Center for Atmospheric Research Community Climate Model simulate the low-level jet rather well, although the spatial distribution of the jet frequency simulated by the two GCMs differs considerably. Sensitivity experiments have demonstrated that the simulated low-level jet is surprisingly robust, with similar simulations at much coarser horizontal and vertical resolutions. However, both GCMs fail to simulate the observed relationship between clouds and the low-level jet. The pronounced nocturnal maximum in thunderstorm frequency associated with the low-level jet is not simulated well by either GCM, with only weak evidence of a nocturnal maximum in the Great Plains."
"7005310521;35944226000;","Atmospheric carbon dioxide and early Eocene climate: A general circulation modeling sensitivity study",1996,"10.1016/0031-0182(95)00012-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029668295&doi=10.1016%2f0031-0182%2895%2900012-7&partnerID=40&md5=af8217ccad8239b68c53108438a1b95a","The early Eocene was the warmest time interval of the past 65 million years. We have investigated the hypothesis that the warm climate of the early Eocene may have been caused by higher-than-present levels of atmospheric carbon dioxide (CO2). We have used an atmospheric general circulation model, the NCAR GENESIS model, coupled to a land surface model and a mixed layer ocean, to examine the sensitivity of early Eocene climate to varying levels of atmospheric CO2. Model cases contained a description of the early Eocene Earth and included either 300, 560, or 1680 ppm atmospheric CO2. Climate responses to increased atmospheric CO2 include (1) increased mean annual global temperature by 2-6°C, and decreased latitudinal surface temperature gradients; (2) maximum warming at high latitudes, especially in the winter season; (3) increased mean global precipitation; (4) increased high latitude clouds. In comparison with geological paleoclimate data, the climate response to increased CO2 does not appear to explain completely the early Eocene latitudinal surface temperature gradient; for example, with the 1680 ppm CO2 case, high latitude oceans and continents are minimally warm enough to match paleoclimate data, while low latitude regions are overly warm when compared to sea surface temperature reconstructions. We conclude that CO2 was very likely at least double the present level during the early Eocene and contributed to the overall character of early Eocene climate. However, consideration of increased poleward oceanic heat transport and/or other factors, may be required to produce model results that more closely agree with marine and terrestrial paleoclimate data, especially at low latitudes. © 1995 Elsevier Science B.V. All rights reserved."
"57206128696;7102774997;","Effect of climate change on hydrologic regime of two climatically different watersheds",1996,"10.1061/(ASCE)1084-0699(1996)1:2(77)","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030112407&doi=10.1061%2f%28ASCE%291084-0699%281996%291%3a2%2877%29&partnerID=40&md5=c8de5f5ac9660eff0a0f4cb51551195f","Hydrologic modeling of the responses of two study watersheds to climate change is presented. The watersheds are the Upper Campbell and the Illecillewaet watersheds located in British Columbia. The first is a maritime watershed located on the eastern slopes of the Vancouver Island mountains; the second is located in the Selkirk Mountains in Eastern British Columbia. The Canadian Climate Centre General Circulation model has been used for the prediction of potential effects of climate change on meteorological parameters. In addition to the changes in the amounts of precipitation and temperature usually assumed in hydrologic climate change studies, other meteorological and climatic parameters also considered are the effect of climate on the spatial distribution of precipitation with elevation, as well as on cloud cover, glaciers, vegetation distribution, vegetation biomass production, and plant physiology. The results showed that the mean annual temperature in the two watersheds could increase by more than 3°C and the annual basinwide precipitation could increase by 7.5% in the Upper Campbell watershed and by about 17% in the Illecillewaet watershed. The higher temperatures changed some snowfall to rainfall and the extra precipitation was mainly in the form of rain. The increase of the CO2 concentration caused stomata closure that reduced evapotranspiration. This effect was compensated by increased biomass in the Upper Campbell watershed, but not in the Illecillewaet watershed. These changes produced higher flows in winter and smaller flows in summer. The largest change in the hydrograph shape was in the Illecillewaet watershed where the mean annual maximum daily flow decreased by about 13% and its frequency was reduced. On the other hand, the mean annual runoff increased by 21%. In contrast, although the shape of the simulated annual hydrograph of the Upper Campbell watershed was not affected, magnitude and frequency of the annual maximum precipitation increased. Also, the mean annual runoff in the Upper Campbell watershed increased by 7.5%. These results indicate that different management procedures may be needed to minimize the effects of climate change on the water resources of the two climatically different watersheds and the regions that they represent."
"7404577357;","Is the polar mesosphere the miner's canary of global change?",1996,"10.1016/0273-1177(95)00855-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029510374&doi=10.1016%2f0273-1177%2895%2900855-9&partnerID=40&md5=c87d53083d4280fc12aec911eaa2608d","The polar mesosphere is an atmospheric region located between latitude 50° and the pole, and between 50 and 90 km. During summer it becomes the coldest region on earth (&lt;130K). This review focuses on past and future alterations of the temperature and water vapor content of this extremely cold region. These two influences are crucial for the formation of mesospheric ice particles in noctilucent clouds (NLC). A recent two-dimensional model study has been conducted of how long-term changes in carbon dioxide (CO2) and methane (CH4) concentrations may modify the temperature and water vapor concentration at mesopause heights. The model is a version of the well-known Garcia-Solomon model, modified to include accurate non-LTE cooling in the CO2 15 μm band. The existence region of NLC is defined as a domain where water-ice is supersaturated. Reduced levels of CO2 and CH4 are found to confine the model NLC existence region to within the perpetually-sunlit polar cap region, where the clouds would no longer be visible to a ground observer. A doubling of CO2 and CH4 could extend the NLC region to mid-latitudes, where they would be observable by a large fraction of the world's population."
"7102389805;6603741426;7202162685;","Clouds, radiation, and the diurnal cycle of sea surface temperature in the tropical western Pacific",1996,"10.1175/1520-0442(1996)009<1712:CRATDC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030513510&doi=10.1175%2f1520-0442%281996%29009%3c1712%3aCRATDC%3e2.0.CO%3b2&partnerID=40&md5=a5fd2b59a279b28d89f791754600b3ba","The relationship among clouds, surface radiation flux, and the sea surface temperature (SST) of the tropical western Pacific Ocean over the diurnal cycle is addressed in the context of the Atmospheric Radiation Measurement (ARM) Program scientific objectives for the tropical western Pacific Ocean. An understanding of the relationship between clouds and SST on a variety of time and space scales is needed to understand fully the cloud-radiation feedback in the tropical oceans and the maintenance of the warm pool. Here the diurnal cycle is emphasized. Data from the TOGA COARE Intensive Observation Period is examined and interpreted using an ocean mixed layer model that includes a parameterization of the ""skin"" temperature, explicit salinity, a surface heat budget that includes the sensible heat flux associated with rain, and the contribution of rain to the surface momentum flux. Using a mix of modeling and observations, three different case studies are examined in detail: clear and calm, clear and windy, and disturbed. For these typical sets of conditions and processes in the tropical ocean warm pool, the upper-ocean structure is clarified so that the skin sea surface temperature, the bulk surface temperature (at a depth of 1 cm), and the temperature at 0.5 and 5 m below the surface (which is the level that buoys and ships routinely observe ""surface"" temperature) can be interpreted. Sensitivity studies are conducted with the model to investigate the roles of wind speed, precipitation, ocean turbidity, and ocean initial state in modulating the radiation-induced diurnal cycle in SST. It is found that in high insolation, low wind regimes that the skin temperature may be as much as 30°C warmer than the 0.5-m buoy temperature. Spatial distribution of the diurnal amplitude of the SST are calculated for the global Tropics, and speculations are made regarding the implication of the SST variability to the tropical climate."
"7201607592;7101677832;7003543851;","Climate parameters from satellite spectral measurements. Part I: Collocated AVHRR and HIRS/2 observations of spectral greenhouse parameter",1996,"10.1175/1520-0442(1996)009<0327:CPFSSM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029730482&doi=10.1175%2f1520-0442%281996%29009%3c0327%3aCPFSSM%3e2.0.CO%3b2&partnerID=40&md5=0a4c7651d62360d74a40f104d1ba46c9","An automated method of monitoring various climate parameters using collocated Advanced Very High Resolution Radiometer (AVHRR) and High-Resolution Infrared Sounder-2 (HIRS/2) observations has been developed. The method, referred to as CHAPS (collocated HIRS/2 and AVHRR products) was implemented during the months of July 1993 and January and July 1994. This paper presents the oceanic cloud screening method and analysis of the spectral greenhouse parameter (gλ for July 1993 and January 1994. In addition, the CHAPS derived clear-sky parameters are compared to the NESDIS historical dataset. There is agreement between NESDIS and CHAPS for the g6.7 and g7.3. The NESDIS 8.2-μm data appears to be cloud contaminated. Through comparison with CHAPS, it is suggested that the mode, rather than the mean, provides the better estimate of the central tendency of the NESDIS clear-sky 8.2-μm radiance distribution, particularly for regions with extensive low-level cloud cover. It is shown that the spectral greenhouse parameter at wavelengths sensitive to middle and upper atmospheric water vapor content is dependent on SST via its connection to large-scale atmospheric circulation patterns. It is also shown that the variability of the spectral greenhouse parameter is strongly a function of latitude at these wavelengths, as well as in spectral regions sensitive to lower-level water vapor. Standard deviations are largest in the Tropics and generally decrease poleward. In contrast, variability in the spectral regions sensitive to uppertropospheric temperature peaks in the middle latitudes and has its minimum in tropical latitudes. Variability in the relationship between gλ and SST shows only a weak dependence on season for channels sensitive to water vapor content. A strong seasonal dependence is found in the g14.2 for the middle-latitude regions associated with changes in the temperature structure of the upper troposphere. The relationship between the spectral greenhouse parameter and the broadband greenhouse parameter is presented and discussed. It is found that the range in broadband g for warm tropical SSTs is driven by spectral changes at wavelengths sensitive to upper-tropospheric water vapor. For cooler SSTs associated with the middle latitudes, the range in g is a function of the spectral greenhouse parameter sensitive to the temperature structure of the upper troposphere."
"6602159587;7004027377;7006117817;7202889256;7005123759;","A vegetation-atmosphere interaction study for Amazonia deforestation using field data and a 'single column' model",1996,"10.1256/smsqj.53101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029750470&doi=10.1256%2fsmsqj.53101&partnerID=40&md5=4dbe9ebfb799ec09a2a43e66ec5c09ec","The recent high deforestation rates in Amazonia have raised the question of how climate, mainly the precipitation patterns, might be affected as pasture land replaces the primary forest. This work initially shows how the dry season soil moisture and water stress in typical Amazonian pasture modifies the energy partitioning at the surface. Low-level moisture convergence is a primary mechanism to trigger convective cloud formation and precipitation. The relationship between moisture convergence and local surface evaporation in generating precipitation in Amazonia is studied utilizing a one-dimensional 'single column' model (SiB-1D). SiB-1D couples a surface-vegetation model (SiB) to a physical parametrization of deep convection (Kuo scheme), radiation, turbulent diffusion and large-scale precipitation. Model simulations for short periods (2 days) show its ability to calculate the Amazonian surface energy-balance components and boundary-layer dynamics when compared with field observations from the Rondônia Boundary-Layer Experiment and the Anglo-Brazilian Amazonian Climate Observation Study. The model was further used to test the sensitivity of the deep convection scheme to a range of typical low-level moisture convergence situations in a second experiment, and a third test investigated the local convective precipitation generated over forest and grass vegetation as a function of available soil moisture. Results showed that the rainfall over forest vegetation appeared to be almost insensitive to soil water stress whereas reduced precipitation was generated over pasture. When available soil water fell below a threshold of 60% the calculated precipitation over the pasture sites rapidly declined. Although these results are confined by the short integration period and the initial atmospheric profiles, they help to strengthen the notion that deforestation reduces evaporation and convective precipitation, especially during the dry season: a result already indicated by some previous general-circulation model experiments."
"7407661878;6701791841;","Contemporary climate change in the Jordan Valley",1996,"10.1175/1520-0450(1996)035<1051:CCCITJ>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030431235&doi=10.1175%2f1520-0450%281996%29035%3c1051%3aCCCITJ%3e2.0.CO%3b2&partnerID=40&md5=6089dc786121fc6a32d17991b4754651","This study examines the climate changes that have occurred in the 40 years since the publication of Jehuda Neumann's classic climatological studies of the energy and water balance of the natural water bodies of the Jordan Valley. The measurements analyzed in this paper were those made during the last half century at three rural sites in the Israel Meteorological Service's climate station network. They consist of 45-60 years of continuous records of daily minimum and maximum temperature, and rainfall and shorter, intermittent pairs of early and recent measurement series of global irradiance, which were available from nearby sites. Annual averages of minimum and maximum temperatures showed statistically significant decreases in mean annual maximum temperatures. These were -0.035°C per year at Kfar Blum (north of the former Hula swamp), -0.024°C per year at Degania A (on the southern shore of Lake Kinneret) and -0.018°C per year at Sedom (near the southern shore of the Dead Sea). Minimum temperatures showed no significant change at Kfar Blum, decreased significantly at Degania by 0.011°C per year and increased significantly by 0.024°C per year at Sedom. The temperature trends showed a complex seasonal pattern. No significant changes in total annual rainfall or its interannual variance were found. Although much of the interannual variance in the temperature records could be explained by the large variations in annual rainfall, annual temperature trends remain unchanged after removal of the rainfall influence. Comparison of the three pairs of global irradiance measurement series made in the Jordan Valley during the 1960s and the 1980s indicates that a marked decrease in irradiance has accompanied the decreases in maximum temperatures, the decrease in irradiance being greatest at the cloudier sites and seasons. Cloud cover observations at Kfar Blum showed that this decrease in irradiance could not be explained by an increase in cloud cover. The results indicate that a significant reduction in atmospheric transmissivity has occurred in this region, possibly caused by the increased emissions of anthropogenic aerosols from the upwind industrialized coastal region of Israel and of Europe. Finally the consequences of the above changes for the agriculture and hydrology of the region are briefly discussed."
"35614191800;7202152077;7103098454;7201789918;7005350396;7406372329;6603617600;","Why the ITCZ is mostly north of the equator",1996,"10.1175/1520-0442(1996)009<2958:WTIIMN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030436584&doi=10.1175%2f1520-0442%281996%29009%3c2958%3aWTIIMN%3e2.0.CO%3b2&partnerID=40&md5=b99710562089b98cb5deabeb69e3c64b","Although the distribution of sunshine is symmetrical about the equator, the earth's climate is not. Climatic asymmetries are prominent in the eastern tropical Pacific and Atlantic Oceans where the regions of maximum sea surface temperature, convective cloud cover, and rainfall are north of the equator. This is the result of two sets of factors: interactions between the ocean and atmosphere that are capable of converting symmetry into asymmetry, and the geometries of the continents that determine in which longitudes the interactions are effective and in which hemisphere the warmest waters and the intertropical convergence zone are located. The ocean-atmosphere interactions are most effective where the thermocline is shallow because the winds can readily affect sea surface temperatures in such regions. The thermocline happens to shoal in the eastern equatorial Pacific and Atlantic, but not in the eastern Indian Ocean, because easterly trade winds prevail over the tropical Atlantic and Pacific whereas monsoons, with a far larger meridional component, are dominant over the Indian Ocean. That is how the global distribution of the continents, by determining the large-scale wind patterns, causes climatic asymmetries to be prominent in some bands of longitude but not others. The explanation for asymmetries that favor the Northern rather than Southern Hemisphere with the warmest waters and the ITCZ involves the details of the local coastal geometries: the bulge of western Africa to the north of the Gulf of Guinea and the slope of the western coast of the Americas relative to meridians. Low-level stratus clouds over cold waters are crucial to the maintenance of the asymmetries."
"7404577357;","Global change in the mesosphere-lower thermosphere region: Has it already arrived?",1996,"10.1016/0021-9169(96)00008-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030438167&doi=10.1016%2f0021-9169%2896%2900008-6&partnerID=40&md5=aff8a4810375e19287540800cfd68e65","This tutorial review describes some possible future scenarios for changes in temperature and water vapor in the mesosphere-lower thermosphere (MLT) region (50-100 km). The structure and dynamics of this region are controlled by physical processes, some of which are very different than in the lower atmosphere, such as gravity-wave breaking, radiative transfer in non-local thermodynamic equilibrium and airglow cooling. The couplings between the various atmospheric properties are illustrated by the use of a 2D zonally-symmetric model ranging from 16 to 120 km. The importance of temperature and water vapor for the occurrence and scattered brightness of mesospheric clouds (at a height of about 83 km) is described in terms of their influence on nucleation, growth and sedimentation of ice particles. At the cold mesopause at high latitude, IR effects would warm the region without dynamical feedbacks, which in the 2D model to be described, cause a net cooling at all latitudes and seasons: The effects of a future doubling of carbon dioxide and methane (and a past halving) are examined by means of the same 2D model. All models predict a future lowering of temperature throughout much, if not all of the MLT region, as a result of enhanced IR cooling and dynamical feedbacks. The rise of methane will lead to an enhancement of water vapor concentrations throughout the upper atmosphere. The cloud existence region, defined in terms of water-ice saturation, is predicted to extend to lower-latitude, high population areas in the future. In a glacial-era scenario, the existence region is found to be confined to a small region near the summertime polar mesopause. Over the past century, with a doubling of methane and a 30% increase in carbon dioxide, the mesospheric cloud existence region may, have advanced from near the pole to its current location inside the 50°-90° latitude zone. The uncertainties in current models and need for further studies are discussed. Copyright © 1996 Elsevier Science Ltd."
"7401559815;57191682632;7004160106;","Intercomparison of hydrologic processes in AMIP GCMs",1996,"10.1175/1520-0477(1996)077<2209:IOHPIA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030357259&doi=10.1175%2f1520-0477%281996%29077%3c2209%3aIOHPIA%3e2.0.CO%3b2&partnerID=40&md5=f11a4938a7f608d95163faed15077c1b","Results of an intercomparison study under the Atmospheric Model Intercomparison Project (AMIP) to assess the abilities of 29 global climate models (GCMs) in simulating various aspects of regional and hydrologic processes in response to observed sea surface temperature and sea ice boundary forcings are presented. The authors find that the models generally portray an earthlike climate to approximately 10%-20% of the global land surface temperature (= 14.8°C) and global precipitation (= 2.3 mm day-1). While a majority of the models have a reasonable global water budget, about a quarter of the models show significant errors in the total global water balance. While the model frequency distributions of heavy precipitation associated with deep convection are in reasonable agreement with observations, a systematic underestimate of the frequency of occurrence of light precipitation events (&lt; 1 mm day-1) is present in almost all the AMIP models, especially over continental desert regions and over tropical and subtropical oceanic regions contiguous to the west coasts of continents where low-level stratocumulus clouds tend to occur. This discrepancy is presumably related to the crude treatment of moist processes, especially those related to low clouds and nonconvective precipitation in the models. Another common problem in the global rainfall distribution is the presence of spectral ram or spurious gridpoint-scale heavy rain. The artificial anchoring of rainfall to topographic features in the Maritime Continent appears to be a generic problem in many GCMs. Models differ substantially in the magnitude of the rainfall amount over the eastern Pacific ITCZ for all seasons. The simulated boreal summer rainfall distributions have large variability over the Indian subcontinent and the Bay of Bengal. The northward migration of the monsoon convective zones are not well simulated. In particular, the East Asian monsoon rainband over the subtropical western Pacific is ill-defined or absent in all models. On the interannual timescale, the models show reasonable skills in simulating the fluctuations of the Southern Oscillation and the eastward migration of the major equatorial precipitation zone during ENSO. Most models show useful rainfall prediction skill in the Tropics associated with ENSO-related SST forcing. However, the models do not show any useful skill for extratropical rainfall prediction from specified anomalous global SST forcing. Overall, the models depict a reasonably realistic annual cycle of water balance over regions where long-term local moisture balance is maintained - that is, (P-E) ≈ 0 - over large interior land regions in the extratropics. In regions of strong dynamic control - that is, (P-E) ≫ 0 - such as the tropical western Pacific, monsoon regions, and the ITCZ, the intermodel variability is very large. The simulated water balance over large river basins has been validated against hydrographic river discharge data using a river-routing model. Results show that while the model ensemble mean runoffs are consistent with the climatological observed river discharge for the Amazon and Mississippi, the intermodel variability is substantial. The models yield even more divergent results over other world river basins. These results suggest that while some GCMs may have moderate capability in capturing some aspects of the climatological variation of runoff, it is premature to use them for climate studies related to continental-scale water balance. A ranking of the AMIP models and some possible implications based on the above performance are also presented."
"7202048112;6601977455;7003666669;7202276745;6603937643;","Application of a subgrid orographic precipitation/surface hydrology scheme to a mountain watershed",1996,"10.1029/96JD00441","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030423552&doi=10.1029%2f96JD00441&partnerID=40&md5=ee73cdf10d49425fb18cc5804eae5395","A regional climate model including a physically based parameterization of the subgrid effects of topography on clouds and precipitation is driven by observed meteorology on its lateral boundaries for a period of 12 months. The meteorology simulated by the model for each subgrid elevation class is distributed across a mountain watershed according to the surface elevation within the watershed. The simulated meteorology is used to drive a detailed model of hydrology-vegetation dynamics at the topographic scale described by digital elevation data, 180 m. The watershed model, which includes a two-layer canopy model for evapotranspiration, an energy-balance model for snow accumulation and melt, a two-layer rooting zone model, and a quasi-three-dimensional saturated subsurface flow model, is used to simulate the seasonal cycle of the accumulation and melt of snow and the accumulation and discharge of surface water within a mountain watershed in northwestern Montana. Comparisons between the simulated and the recorded snow cover and river discharge at the base of the watershed indicate comparable if not better agreement than between the recorded fields and those simulated by the watershed model driven by meteorology observed at two stations within the watershed. The agreement with the recorded discharge, precipitation, and snow water equivalent is also clearly superior to simulations driven by the regional climate model run without the subgrid parameterization but with one-third the grid size of the simulation with the subgrid parameterization. Copyright 1996 by the American Geophysical Union."
"35354658400;7004314981;16187255400;","Climate implications of biomass burning since the 19th century in eastern North America",1996,"10.1111/j.1365-2486.1996.tb00093.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030389859&doi=10.1111%2fj.1365-2486.1996.tb00093.x&partnerID=40&md5=31825921f624066347877032c62a3042","Recent predictions that tropospheric aerosols have counterbalanced greenhouse warming assume aerosol emissions were low before AD1850 and then increased dramatically with industrialization of the Northern Hemisphere and biomass burning in the Tropics. We assembled the lake sediment record of emissions across northeastern North America, where temperatures are predicted to have been substantially affected by industrial aerosols. Sediment evidence suggests a systematic shift in source and an overall decline in emissions since the 19th century. The geographical shift results from high presettlement emissions from wildfires in the Midwest that collapsed with tillage and fire suppression. Meanwhile, emissions were increasing in the North-east with European settlement. These regional changes produced a shift from the continental interior to the North-east. An overall decline results because decreases in the Midwest more than compensate for increases in the North-east. Results suggest the Central Plains as an important source of emissions in the recent past, consistent with pioneer accounts of dense smoke clouds emanating from prairie in the 19th century. Contrary to recent models that suggest increased 20th century combustion emissions could have offset warming effects of rising greenhouse gases, our data suggest that aerosols could have actually decreased over this interval. Although we cannot directly quantify aerosols from our methods, the emissions of large particles suggest assumptions of 20th century aerosol declines should be reconsidered. © 1996 Blackwell Science Ltd."
"56157800800;","A sensitivity study of changes in Earth's rotation rate with an atmospheric general circulation model",1996,"10.1016/0921-8181(95)00050-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029774523&doi=10.1016%2f0921-8181%2895%2900050-X&partnerID=40&md5=1f82ca322e4cd65da86e9b436bc9f00c","A series of general circulation model simulations in which Earth's rotation rate has been increased is presented using the community climate model version l (CCM1) of the National Center for Atmospheric Research (NCAR). The rotation rate has been altered in order to simulate day-lengths of 24-, 22-, 20-, 18-, 16- and 14-h Earth days. This is a plausible range of Earth's day-length during the last 4 billion years. In an earlier study with a simple energy balance ocean, which does not store heat (sometimes referred to as a swamp), it was shown that reducing the day-length to a 14-h day caused a 20% reduction in the global mean cloud fraction. In this study however, using fixed sea surface temperatures (SSTs) with January solar forcing, a slight increase in clouds occurs with faster rotation, although changes in relative humidity are similar to the earlier study. Furthermore, as in an earlier study, there is more sinking in the mid-latitudes. This sinking is most prominent over the Pacific and Atlantic storm tracks, indicating that the baroclinic eddies have been weakened. With faster rotation rates, the storm tracks are defined by shorter waves as compared to the control simulation. A significant change in the large-scale zonally averaged circulation occurs when the day-length is reduced to a values less than 18-hours. The effects of faster rotation rates on stationary eddy heat transport may help to explain high latitude glaciation of the Ordovician some 440 Ma years ago. © 1996 Elsevier Science B.V. All rights reserved."
"7003363471;7005174366;7004102200;","El Niño and tree growth near Jerusalem over the last 20 years",1996,"10.1111/j.1365-2486.1996.tb00054.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030484764&doi=10.1111%2fj.1365-2486.1996.tb00054.x&partnerID=40&md5=b215e84360aee508684d141a6a73e815","A strong correlation is observed between an El Nino index (anomalies in tropical Pacific sea surface temperature) and rainfall in the Judean foothills near Jerusalem over the past 20 years. These relationships clearly influenced the growth of local pine trees, as reflected in the width of their annual tree rings. The ability to predict El Nino events about a year in advance lend a special significance to relationships reported here for ecology, agriculture and water management in this climatic transition zone. To help explain the observed, long-range teleconnection we propose a possible mechanism based on a newly identified direct cloud connection between equatorial Africa (more directly affected by El Nino) and the Southeastern Mediterranean shoreland. The penetration and contribution of the moisture current from equatorial Africa to this region may depend on a shift in the usual rain generating moisture currents to southwesterly trajectories (passing over north Africa). The occurrence of such shifts is supported by the observed decrease in the mean 18O content of the local precipitation during El Niño winters. © 1996 Blackwell Science Ltd."
"7102953444;6602146732;57206414200;","Regional climate simulation with a high resolution GCM: Surface hydrology",1996,"10.1007/s003820050141","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030372341&doi=10.1007%2fs003820050141&partnerID=40&md5=b9e8721ab60e538256efeb5f5f0efd5e","Aspects of the surface hydrology of high resolution (T106) versions of the ECHAM3 and ECHAM4 general circulation models are analysed over the European region and compared with available observations. The focus is on evaporation, and surface measurements are shown to be useful for the identification of systematic deficiencies in the regional-scale performance of climate models on an annual and sea-sonal basis, such as the excessive summer dryness over continents. The annual mean evaporation at the available European observation sites is overestimated by 4 mm/month by the ECHAM3 T106, quantitatively consistent with an overestimated surface net radiation of 4 Wm-2 over Europe. In winter, ECHAM3 shows an overestimated evaporation which compensates for an overestimated downward sensible heat flux. This is primarily related to a too strong zonalisation of the large-scale flow and associated overestimated warm air advection and windspeed. Inaccurate local land surface parameters (e.g. leaf area index, roughness length) are minor contributors to the overestimation. In early summer, the excessive solar radiation at the surface calculated with the ECHAM3 radiation scheme generates a too large evaporation and an excessive depletion of the soil moisture reservoirs. This favours the subsequent excessive summer dryness over Europe with too low values of evaporation, convective precipitation and soil moisture content, leading to a too high surface temperature. In the ECHAM4 T106 simulation, the problem of the European summer dryness is largely reduced, and the simulated evaporation as well as convective precipitation, cloud amount and soil moisture content during summer are substantially improved. The new ECHAM4 radiation scheme appears to be an important factor for this improvement, since it calculates smaller insolation values in better agreement with observations and subsequently may avoid an excessive drying of the soil."
"7406372329;35614191800;","On the annual cycle of the eastern equatorial Pacific",1996,"10.1175/1520-0442(1996)009<2986:OTACOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030437332&doi=10.1175%2f1520-0442%281996%29009%3c2986%3aOTACOT%3e2.0.CO%3b2&partnerID=40&md5=dc3b382c9f032fe6d72461944f6b84f1","Although the sun ""crosses"" the equator twice a year, the eastern equatorial Pacific has a pronounced annual cycle, in sea surface temperature and in both components of the surface winds for example. (This is in contrast to the Indian Ocean and western Pacific where a semiannual oscillation of the zonal wind is the dominant signal on the equator.) Calculations with a relatively simple coupled ocean-atmosphere model indicate that the principal reason for this phenomenon is the marked asymmetry, relative to the equator, of the time-averaged climatic conditions in the eastern tropical Pacific. The important asymmetries are in surface winds, oceanic currents, and sea surface temperature: The time-averaged winds and currents have northward components at the equator and the warmest waters are north of the equator. Because of those asymmetries, seasonally varying solar radiation that is strictly antisymmetric relative to the equator can force a response that has a symmetric component. The amplitude of the resultant annual cycle at the equator depends on interactions between the ocean and atmosphere, and on positive feedbacks that involve low-level stratus clouds that form over cold surface waters."
"7004314335;7202942587;","Ozone concentration profiles in the Los Angeles Basin - A possible similarity in the build-up mechanism of inland surface ozone in Israel",1996,"10.1175/1520-0450(1996)035<1085:OCPITL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030432681&doi=10.1175%2f1520-0450%281996%29035%3c1085%3aOCPITL%3e2.0.CO%3b2&partnerID=40&md5=306ce6991d6d07647bbe5a143ad1ca3d","This paper analyzes some measurements of the Southern California Air Quality Study, which collected a comprehensive air quality, meteorological, and emissions database in the Los Angeles Basin. This analysis emphasizes the interaction of the enriched ozone layer existing aloft with the top of the convective boundary layer (CBL) in the early afternoon of warm summer days, leading to downward mixing (fumigation) of the ozone cloud toward the ground. This process was shown to contribute to the high ozone concentrations measured at inland elevated sites. It is suggested that this mechanism also exists in Israel and contributes to the elevated concentrations observed in the summer on the slopes of the Judean Hills. This analogy is based on the similarity between the Los Angeles Basin and central Israel regarding the climate, the local circulation (sea breeze), the orientation of the coast, and the upwind location of ozone precursor sources. The temporal fluctuations of the synoptic configuration persisting over Israel during the summer cause rapid variations in the depth of the CBL inland and its subsequent interaction with an ozone layer aloft."
"7003813395;7006432374;6602995749;7003633453;","The application of throughfall measurements for atmospheric deposition monitoring",1996,"10.1016/1352-2310(96)00030-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030251177&doi=10.1016%2f1352-2310%2896%2900030-1&partnerID=40&md5=340058986102967a7444b40b5842b8c8","An overview of the technical requirements of throughfall, stemflow and precipitation measurements used for monitoring atmospheric deposition to forests is presented. A mechanistic basis is presented to link throughfall fluxes to atmospheric deposition. For homogeneous forest stands with a closed canopy, the overall uncertainty in annual mean soil loads can be as low as 10-15% if state-of-the-art measurement and analytical techniques are used in combination with a sufficiently large number of replicate samplers. The uncertainty in atmospheric deposition estimates, however, is estimated much larger, i.e. up to 30% for sulphur and 40% for nitrogen and base cations. This is mainly attributed to (i) uncertainties associated with the estimation of canopy exchange, and (ii) dry deposition to the forest floor and understorey vegetation which is usually not addressed in throughfall studies. Additional research on canopy exchange in relation to tree species, ecological setting and pollution climate is recommended, especially for nitrogen compounds and base cations, and may serve as a basis for improvement of current canopy budget models."
"7102270856;8881684500;56251144600;57203238681;","Laurel forests in Tenerife, Canary Islands: I. The site, stand structure and stand leaf area distribution",1996,"10.1007/s004680050055","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030472302&doi=10.1007%2fs004680050055&partnerID=40&md5=494b686c23fdf9d8e023624481c2e9cc","Stand structure and leaf area distribution of a laurel forest in the Agua García mountains of Tenerife are described. The site is situated at 820 m a.s.l, faces NNE, and has a humid mediterranean climate. Summer droughts are mitigated by relatively high air humidity and clouds. The natural mixed hardwood forest is composed of six major tree species: Laurus azorica (Seub.) Franco, Persea indica (L.) Spreng, Myrica faya Ait., Erica arborea L. and two species of Ilex (I. platyphylla Webb &amp; Berth, and I. canariensis Poivet.). The experimental stand had a density of 1693 trees ha-1, a basal area of 33.7 m2ha-1, and a cumulated volume of above-ground parts of trees of 231 m3 ha-1 with a corresponding dry mass of 204 ton ha-1. Diameters at breast height ranged from 6 to 46 cm. Mean concentration of plant dry mass per volume was 1.17 kg m-3. The vertical pattern of leaf area distribution in individual trees for all tree species was characterized by a Gaussian-like curve. Stand leaf area index was 7.8. These evergreen, broad-leaved (laurisilva or lucidophyllous) forests represent a relic forest that was widespread in the Mediterranean region some 20 million years ago. Our data illustrate some of the structural characteristics of this historically widespread forest type."
"6601977242;7202706097;7103293232;","Ocean mixed layer radiant heating and solar penetration: A global analysis",1996,"10.1175/1520-0442(1996)009<2265:OMLRHA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030438978&doi=10.1175%2f1520-0442%281996%29009%3c2265%3aOMLRHA%3e2.0.CO%3b2&partnerID=40&md5=d505d0f84803af4ba1cf16b4bf66f918","A hybrid parameterization for the determination of in-water solar fluxes is developed and applied to compute the flux of solar radiation that penetrates beyond the upper-ocean mixed layer into permanent pycnocline waters on global space and climatological timescales. The net flux of solar radiation at depth is modeled using values of the solar flux incident at the sea surface, derived from the International Satellite Cloud Climatology Project dataset, and in-water attenuation coefficients, determined using upper ocean chlorophyll concentration supplied by Coastal Zone Color Scanner imagery. Solar radiation penetration can be a significant term (20 W m-2) in the mixed layer heat budget for tropical regions. In mid- and high-latitude regions, the annual solar flux entering permanent pycnocline waters is small (&lt;5 W m-2). However, solar penetration in these regions is important on seasonal timescales since annual cycles in incident solar flux, upper-ocean chlorophyll concentration, and mixed layer depth cause trapping of penetrating solar energy of O ( 10 W m-2) within the seasonal pycnocline. This trapped thermal energy is unavailable for atmospheric exchange until winter - a period as long as nine months. A nondimensional parameter is introduced that quantifies the fraction of incident solar radiation contributing to mixed layer radiant heating. This parameter can be used to characterize the relative importance of solar penetration to ocean mixed layer thermal climate."
"7003912723;6603387582;","Variational analysis of humidity information from TOVS radiances",1996,"10.1256/smsqj.53503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030404333&doi=10.1256%2fsmsqj.53503&partnerID=40&md5=2f8f99d9cfa22c30c0a75e6c9ada7abc","The impact of assimilating TOVS radiance data in the European Centre for Medium-Range Weather Forecasts humidity analysis is evaluated. It has been found that the introduction of a one-dimensional variational analysis scheme (1DVAR) applied to the TOVS radiances significantly improves the representation of many aspects of the hydrological cycle. The theoretical information content of the TOVS radiance data is discussed and found to be consistent with significant changes observed in the mid upper-tropospheric moisture fields when the radiance data are assimilated. In particular, a tendency of the model (without radiance assimilation) to produce a tropical humidity structure that is far too dry is removed, and excessively moist conditions in the southern sub-tropics are improved. It is argued that the latter problem originates from the use of operational NESDIS retrieved products in the analysis. The humidity adjustments caused by the assimilation of TOVS radiances are accompanied by significant changes in the model dynamics, especially the description of the tropical Hadley circulation. One such case is described in detail, where the moistening of the tropics and drying of the sub-tropics has resulted in a stronger mean analysed meridional circulation in the Atlantic. The analysis changes are also shown to improve the medium-range forecasting of humidity, together with some associated benefit in the prediction of cloud and precipitation."
"7006806637;7102474236;","The HartX period May 1992, seen against the background of twenty years of energy balance climatology at the Hartheim pine plantation",1996,"10.1007/BF00866407","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030452562&doi=10.1007%2fBF00866407&partnerID=40&md5=3e65fcfd91990360ff066fb4316c3614","The experimental site of the Department of Meteorology of Freiburg University at the Hartheim pine stand is first described. There, since 1973 long term measurements of net radiation and its components have been carried out. In addition we have been monitoring the different heat fluxes and components of the forest water budget. From May 11th to May 24th 1992 a special international and interdisciplinary observation period was organized in Hartheim (HartX 92). This took place in the frame of the international regional climatic project REKLIP (Regionales Klima Projekt). We then describe the permanent equipment and the special HartX installations. After that we show the climate of the region, in May 1992 and the weather during the HartX period. It was extraordinarily warm and the precipitation was much less than normal. The cloud cover was very small. We report the results of the radiation measurements (net radiation and its components). They are compared to the long standing measurements (1974-1988). Moreover the longstanding data of the components of the water budget (throughfall, canopy drip and stemflow, interception and transpiration) of the period 1978-1985 are dealt with. In addition we report the behaviour of the energy fluxes (soil-stand heat flux, turbulent sensible and latent heat fluxes) of the period 1974-1988. These estimations are compared to the conditions in May 1992 and the conditions during HartX 92."
"16643212300;7003287025;36776522500;6508098656;","Polar lows in the Labrador Sea: A case study",1996,"10.1034/j.1600-0870.1996.00002.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029749839&doi=10.1034%2fj.1600-0870.1996.00002.x&partnerID=40&md5=7dc7f7a889a1860226946694011ac72b","In this paper, we will describe our analysis of a polar low event that occurred in the Labrador Sea during the winter of 1992. As there are unfortunately no in-situ observations of this event, we will rely on satellite data as well as the high-resolution objective analaysis from the ECMWF to document the environment in which the low developed and the structure of the low itself. We will show that the polar low developed during a cold air outbreak that was precipitated by the passage of an intense synoptic-scale low. The polar low appears to have developed along a linear cloud feature as the result of an interaction between a low-level diabatically induced potential vorticity anomaly and an upper-level potential vorticity anomaly that propagated into the area from the Canadian Arctic. We will also show that with the TOMS and TOVS retrievals for total column ozone, we are able to identify a signature of the upper-level potential vorticity anomaly. In its mature state, we will show that there were very strong winds, and as a result large fluxes of sensible and latent heat, associated with the polar low. In summary, the 1992 Labrador Sea polar low provides one with an excellent opportunity to study air-sea interactions and the coupling between the troposphere and stratosphere. The realization that the strong heating of the atmosphere and the concomitant cooling of the ocean associated with these storms may be sufficient to initiate downwelling events in the ocean may represent a hitherto undocumented link between the fast and slow climate systems that deserves further attention."
"7201468792;7404211378;","Summer climate variability in China and its association with 500 hPa height and tropical convection",1996,"10.2151/jmsj1965.74.4_425","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0039331642&doi=10.2151%2fjmsj1965.74.4_425&partnerID=40&md5=921d337fb4ce295ba3cc9eff16489814","This paper is concernd with interannual and interdecadal variabilities of summer rainfall and temperature patterns in China and their association with 500 hPa height in the Northern Hemisphere (NH), tropical convective activities and global sea surface temperature anomaly (SSTA). The temporal evolutions and spatial structures of interannual variation of summer (JJA) rainfall and temperature from 1951 to 1994 over China are revealed through EOF analysis. The spatial pattern of EOF1 for rainfall (EOF1.R) is dominated by a maximum over the middle-lower reaches of the Yangtze River, and a large negative value region in the middle reach of the Yellow River is also obvious. The spatial pattern of EOF1 for temperature (EOF1.T) reflects coherent variations over most regions of China, and it is dominated by a maximum over the middle-lower reaches of the Yangtze River. Linear increase and decrease trends are found in the time coefficients of EOF1.R and EOF1.T, respectively. The quasi-biennial oscillation (QBO) signal is also strong after the middle of the 1970's in repect of their time coefficients. The coupled patterns of rainfall and temperature are picked up through the singular value decomposition (SVD) analysis. The spatial patterns and their temporal evolutions of SVD1 for rainfall (SVD1.R) and SVD1 for temperature (SVD1.T) are quite similar to those of EOF1.R and EOF1.T. There is an abrupt change in the middle 1970's in the time coefficients of SVD2.R and SVD2.T. The variations of summer rainfall and temperature coupled patterns in China are closely connected with the 500 hPa height anomaly over the Northern Hemisphere (NH). The Pacific-Japan (PJ) and Eurasia (EU) teleconnection patterns play a very important role in the spatial patterns of SVD1.R and SVD1.T, especially in the East Asia monsoon region along the middle-lower reaches of the Yangtze River. The abrupt change of China summer climate in the middle 1970's is related with the intensification and southerly location of the western Pacific subtropical high and also the geopotential height changes over Eurasia and in the regions to the north of the Japan Sea in 1977 or 1978. Correlations between the summer rainfall and temperature coupled patterns and monthly-averaged outgoing longwave radiation (OLR) and high-cloud amount (HCA) data are significant with the PJ teleconnection pattern. There exist positive correlations between the coupled patterns and sea surface temperature anomaly (SSTA) in the Nort h Pacific and the tropical western Pacific. A comparison study shows that there are coherent variations between summer rainfall in the middle-lower reaches of the Yangtze River and in the western part of Japan. It is also demonstrated that there are close correlations between the summer temperature variations in China and in Japan."
"6601983420;","Improvements in quantitative precipitation forecasts with the eta regional model at the national centers for environmental prediction: The 48-km upgrade",1996,"10.1175/1520-0477(1996)077<2637:IIQPFW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030410955&doi=10.1175%2f1520-0477%281996%29077%3c2637%3aIIQPFW%3e2.0.CO%3b2&partnerID=40&md5=3cc0f9dd1e6c3493d615269ea6a7e425","Since 9 June 1993, the eta coordinate regional model has been run twice daily at the National Centers for Environmental Prediction (NCEP, previously the National Meteorological Center) as the NCEP's ""early"" operational model. Its performance is regularly monitored in a variety of ways, with particular attention given to precipitation forecasts. Throughout this period, the eta model has demonstrated significantly increased accuracy in forecasting daily precipitation amounts compared to NCEP's Nested Grid Model (NGM). The model has shown a smaller but equally consistent advantage in skill against that of NCEP's global spectral model. Precipitation scores of these three operational models for the 6-month period March-August 1995 are presented. This interval is chosen because the 6-month-long periods September-February and March-August have been used in previous model comparisons and because an upgraded version of the eta model, run at 48-km resolution, was also regularly executed twice daily during the March-August 1995 period. It is thus included and highlighted in the present comparison. The 48-km eta carries cloud water as a prognostic variable and is coupled to a 12-h eta-based intermittent data assimilation system. It replaced the 80-km eta as the NCEP's early operational model on 12 October 1995. Compared to the then-operational 80-km cta, the 48-km eta has demonstrated substantially increased skill at all eight precipitation categories for which verifications are made. The increase in skill was greatest for the most intense precipitation, at the threshold of 2 in. (24 h)-1. A 24-48-h forecast of accumulated precipitation, resulting from Hurricane Allison as it was crossing the extreme southeastern United States, is shown as an example of a successful forecast of intense precipitation by the 48-km model. Reasons for the advantage of the eta model over its predecessor, the NGM, are reviewed. The work in progress is outlined."
"7401945370;55709811600;","Response of the atmospheric angular momentum and the length of the day to the surface temperature increase for an aqua planet model",1996,"10.1029/96GL02211","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030234136&doi=10.1029%2f96GL02211&partnerID=40&md5=f2a135c0a2a7a6c664b6f1fe3eea46da","We examine the effect of the surface temperature increase on the atmospheric angular momentum to study relations between the decadal variations in the atmospheric angular momentum and those of the rotation of the solid earth. We use an atmospheric general circulation model forced by simple surface temperature distributions (an aqua planet model). We vary the temperature distribution in two ways and investigate the responses. In one set of calculations, the surface temperature is increased uniformly globally. In the other set of calculations, the surface temperature is increased locally near the equator. We have found that a globally uniform warming results in an increase of the atmospheric angular momentum. This is because the tropopause becomes higher and the depth of tropospheric westerly shear increases as the surface temperature increases. The altitude of the jet (maximum of the westerlies) increases, while its latitude does not change. These dependencies can be explained by the dynamics of the Hadley circulation. We have also found that a warming localized near the equator results in an westerly jet built up around the equatorial tropopause and the increase in the angular momentum. The results of the two cases investigated here show that the effect of warming on the atmospheric angular momentum is too small to explain the decadal variations of the length of the day. Furthermore, they show that the sense of the change is opposite to that proposed by Lambeck and Cazenave [1976], which is based on observational data of the lower atmosphere. Copyright 1996 by the American Geophysical Union."
"57203078473;","Chemical compounds in the remote Pacific troposphere: Comparison between MLOPEX measurements and chemical transport model calculations",1996,"10.1029/95JD03520","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029853612&doi=10.1029%2f95JD03520&partnerID=40&md5=4fc51adf4c2d437940b26b9c941cf410","A global three-dimensional chemical transport model, called MOZART (Model of OZone And Related species in the Troposphere), is used to compare calculated abundances of chemical species and their seasonal evolution in the remote Pacific troposphere near Hawaii with values observed during the Mauna Loa Observatory Photochemistry Experimeats (MLOPEX 1 and 2). MOZART is a fully diurnal model which calculates the time evolution of about 30 chemical species from the surface to the upper stratosphere. It accounts for surface emissions of source gases, wet and dry depositions, photochemical transformations and transport processes. The dynamical variables are provided by the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2) at T42 resolution (2.8°×2.8°) and 18 levels in the vertical. Simulated abundances of 222Rn reveal an underestimate of the transport of continental emissions to the remote Pacific troposphere, more particularly during winter and summer. Calculated concentrations of chemical species are generally in fair agreement with observations. However, the abundances of soluble species are overestimated, leading, for example, to concentrations of nitric acid (HNO3) and hydrogen peroxide (H2O2) which are overpredicted by a factor of 3-8, depending on the season. This feature is attributed to insufficient washout by clouds and precipitation in the model. MOZART succesfully reproduces the development of high-NOx episodes at Mauna Loa Observatory (MLO) associated with anticyclonic conditions to the north of Hawaii and breakdown of the polar jet which tends to deflect to the central Pacific the flow of NOx transported from eastern Asia (China, Japan). During high NOx episodes, the calculated NOx mixing ratio in the vicinity of the MLO increases by about a factor of 3 over its background level (reaching 90-100 pptv) within 3-5 days. Copyright 1996 by the American Geophysical Union."
"7006413710;7402491471;","Use of remote sensing for evapotranspiration monitoring over land surfaces [Utilisation de la télédétection pour le suivi de l'évapotranspiration sur les terres]",1996,"10.1080/02626669609491522","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030208596&doi=10.1080%2f02626669609491522&partnerID=40&md5=209eee35956ee334a42cc77f27bb8aad","Monitoring evapotranspiration (ET) at large scales is important for assessing climate and anthropogenic effects on natural and agricultural ecosystems. This paper describes techniques used in evaluating ET with remote sensing, which is the only technology that can efficiently and economically provide regional and global coverage. Some of the empirical/statistical techniques have been used operationally with satellite data for computing daily ET at regional scales. The more complex numerical simulation models require detailed input parameters that may limit their application to regions containing a large database of soils and vegetation properties. Current efforts are being directed towards simplifying the parameter requirements of these models. Essentially all energy balance models rely on an estimate of the available energy (net radiation less soil heat flux). Net radiation is not easily determined from space, although progress is being made. Simplified approaches for estimating soil heat flux appear promising for operational applications. In addition, most ET models utilize remote sensing data in the shortwave and thermal wavelengths to measure key boundary conditions. Differences between the radiometric surface temperature and aerodynamic temperature can be significant and progress in incorporating this effect is evident. Atmospheric effects on optical data are significant, and optical sensors cannot see through clouds. This has led some to use microwave observations as a surrogate for optical data to provide estimates of surface moisture and surface temperature; preliminary results are encouraging. The approaches that appear most promising use surface temperature and vegetation indices or a time rate of change in surface temperature coupled to an atmospheric boundary layer model. For many of these models, differences with ET observations can be as low as 20% from hourly to daily time scales, approaching the level of uncertainty in the measurement of ET and contradicting some recent pessimistic conclusions concerning the utility of remotely sensed radiometric surface temperature for determining the surface energy balance. © 1996 Taylor & Francis Group, LLC."
"6602450405;57214702549;7003683808;6504281821;","Feedbacks in one-dimensional climatic models with cloud formation block",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029433132&partnerID=40&md5=ac1b9d8a3ae3a6704cfa19cbe2ec5764","The study of feedback mechanisms caused by changes in the water vapor, the lapse rate in the troposphere, and cloudiness is carried out with the aid of the 1D radiative-dynamic climate model. The climate warming due to doubling of the CO2 and a 2% rise in the solar constant is calculated with use of this model. The resulting values of underlying surface heating do not exceed 1.0 K, which is much smaller than those obtained in the framework of the standard 1D radiative-convective models. The results also demonstrate a decrease in the vertical size and the liquid-water content for clouds of the lower layer and, therefore, a decrease in their optical thickness."
"7004540083;57126848900;","Monitoring changes of clouds",1995,"10.1007/BF01095151","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029510879&doi=10.1007%2fBF01095151&partnerID=40&md5=6696122f04ef6dbef60020763202a2a6","An analysis of the spatial and temporal scales of cloud variability and their coupling provided by the results from existing cloud observing systems allows us to reach the following conclusions about the necessary attributes of a cloud monitoring system. (1) Complete global coverage with uniform density is necessary to obtain an unbiased estimate of cloud change and an estimate of the reliability with which that change can be determined. (2) A spatial sampling interval of less than 50 km is required so that cloud cover distributions will generally be homogeneous, or statistically homogeneous, within a sample. (3) A sampling frequency of at least six times a day ensures not only that the diurnal and semi-diurnal cycles are not aliased into long term mean values, but also that changes in them can be monitored. (4) Since estimated climate changes are only evident on a decadal time-scale, unless cloud monitoring is continuous with a record length greater than 10 years and has very high precision (≈ 1%) instrument calibration with overlapping observations between each pair of instruments, it will not be possible either to detect or to diagnose the effects of cloud changes on the climate. © 1995 Kluwer Academic Publishers."
"55954833500;7102816537;56506988700;57213947375;","Mt. Brocken, a site for a cloud chemistry measurement programme in Central Europe",1995,"10.1007/BF01186124","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029635881&doi=10.1007%2fBF01186124&partnerID=40&md5=e7f366a7ab7cbd8427dde9df7c328059","We present results from the Brocken Cloud Chemistry Measurement Project (BROCCMON) which started in 1991. Since 1992 the full programme is running, based on continuous measurements (e.g. trace gases, meteorology, liquid water content), cloud water sampling and analysis and intensive measurement campaigns. The observed high variability of cloud water composition we explain with cloud dynamic and microphysical behaviour of clouds and differences in the air mass characteristics. During the measurement period 1992-1994 we observed an increase in cloud water acidity (by a factor of 3) and we found photochemical conditions typically for summersmog situations. Our preliminary data also show that an understanding of tropospheric ozone balance would be incomplete without consideration of chemical processes within clouds. A long-term goal of our programme is to establish a cloud chemistry climatology which is representative for the region. © 1995 Kluwer Academic Publishers."
"7004584327;6603954654;7103153652;56141063400;","Dimethylsulfide, algal pigments and light in an Antarctic Phaeocystis sp. bloom",1995,"10.1007/BF00347137","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029486208&doi=10.1007%2fBF00347137&partnerID=40&md5=5126397f97277b818066377866e24a66","Dimethylsulfide (DMS) concentrations in sea water were found to be high (0.19 to 390 n M) in an Antarctic bloom of Phaeocystis sp. during October and November 1990. DMS concentrations were positively correlated with algal pigments, particularly 19′-hexanoyloxyfucoxanthin, a prymnesiophyte pigment. Concentrations of DMS varied diurnally, possibly due to effects of sunlight, although the exact mechanism is unknown. Since oceanic DMS production has been linked to the global albedo through the formation of cloud condensation nuclei, light-mediated changes in DMS concentrations may affect the global climate. The flux of DMS from this bloom into the atmosphere is calculated to be 67±55 μmol m-2 d-1. © 1995 Springer-Verlag."
"7102953444;57202413846;7003630824;7003979342;","Regional climate simulation with a high resolution GCM: surface radiative fluxes",1995,"10.1007/BF00207196","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000938654&doi=10.1007%2fBF00207196&partnerID=40&md5=4c5a8e4ceb7de83aa4c64517239f7880","The ability of a high resolution (T106) version of the ECHAM3 general circulation model to simulate regional scale surface radiative fluxes has been assessed using observations from a new compilation of worldwide instrumentally-measured surface fluxes (Global Energy Balance Archive, GEBA). The focus is on the European region where the highest density of observations is found, and their use for the validation of global and regional climate models is demonstrated. The available data allow a separate assessment of the simulated fluxes of surface shortwave, longwave, and net radiation for this region. In summer, the incoming shortwave radiation calculated by the ECHAM3/T106 model is overestimated by 45 W m-2 over most of Europe, which implies a largely unrealistic forcing on the model surface scheme and excessive surface temperatures. In winter, too little incoming shortwave radiation reaches the model surface. Similar tendencies are found over large areas of the mid-latitudes. These biases are consistent with deficiencies in the simulation of cloud amount, relative humidity and clear sky radiative transfer. The incoming longwave radiation is underestimated at the European GEBA stations predominantly in summer. This largely compensates for the excessive shortwave flux, leading to annual mean net radiation values over Europe close to observations due to error cancellation, a feature already noted in the simulated global mean values in an earlier study. Furthermore, the annual cycle of the simulated surface net radiation is strongly affected by the deficiencies in the simulated incoming shortwave radiation. The high horizontal resolution of the GCM allows an assessment of orographically induced flux gradients based on observations from the European Alps. Although the model-calculated and observed flux fields substantially differ in their absolute values, several aspects of their gradients are realistically captured. The deficiencies identified in the model fields are generally consistent at most stations, indicating a high degree of representativeness of the measurements for their larger scale setting. © 1995 Springer-Verlag."
"7003985371;","Worldwide environmental impacts from the eruption of Thera",1995,"10.1007/BF00768739","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029416057&doi=10.1007%2fBF00768739&partnerID=40&md5=022b59c5628950df3c18b76e0bda4f05","The eruptions of Thera (Santorini) between 1628 and 1450 BC constituted a natural catastrophe unparalleled in all of history. The last major eruption in 1450 BC destroyed the entire Minoan Fleet at Crete at a time when the Minoans dominated the Mediterranean world. In addition, there had to be massive loss of life from ejecta gases, volcanic ash, bombs, and flows. The collapse of a majestic mountain into a caldera 15 km in diameter caused a giant ocean wave, a tsunami, that at its source was estimated in excess of 46 m high. The tsunami destroyed ships as far away as Crete (105 km) and killed thousands of people along the shorelines in the eastern Mediterranean area. At distant points in Asia Minor and Africa, there was darkness from ash fallout, lightning, and destructive earthquakes. Earthquake waves emanating from the epicenter near the ancient volcano were felt as far away as the Norwegian countries. These disturbances caused great physical damage in the eastern Mediterranean and along the rift valley system from Turkey to the south into central Africa. They caused major damage and fires in north Africa from Sinai to Alexandria, Egypt. Volcanic ash spread upward as a pillar of fire and clouds into the atmosphere and blocked out the sun for many days. The ash reached the stratosphere and moved around the world where the associated gases and fine particulate matter impacted the atmosphere, soils, and waters. Ground-hugging, billowing gases moved along the water surface and destroyed all life downwind, probably killing those who attempted to flee from Thera. The deadly gases probably reached the shores of north Africa. Climatic changes were the aftermath of the eruption and the atmospheric plume was to eventually affect the bristlecone pine of California; the bog oaks of Ireland, England, and Germany, and the grain crops of China. Historical eruptions at Krakatau, Tambora, Vesuvius, and, more currently, eruptions at Nevado del Ruiz, Pinatubo, and Mount Saint Helens, have done massive environmental damage but none can compare with the sociological, religious, economic, agricultural, and political impacts from Thera (Santorini). Major natural catastrophes that have occurred over historical time illustrate the force of nature and the impact on civilizations. Some examples of these are rains that flooded the Euphrates Valley during the time of Noah, and floods, earthquakes, and hurricanes in recent years, such as earthquakes in California and Hurricane Hugo on the east coast of the United States. © 1995 Springer-Verlag."
"7402435469;7005513582;7005814217;","Climate sensitivity of the NCAR Community Climate Model (CCM2) to horizontal resolution",1995,"10.1007/BF00209513","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029472647&doi=10.1007%2fBF00209513&partnerID=40&md5=9662ec03d61d420c49d6c57c07ad8f6d","The dependence on horizontal resolution of the climate simulated by the National Center for Atmospheric Research Community Climate Model (CCM2) is explored. Simulations employing R15, T21, T31, T42, T63, and T106 horizontal spectral truncations are compared. Parameters associated with the diagnostic cloud scheme are modified for each resolution to provide similar global average cloud radiative forcing at each resolution. Overall, as with earlier studies, there are large differences between the low resolution R15 and T21 simulations and the medium resolution T42 simulation. Many climate statistics show a monotonic signal with increasing resolution, with the largest variation occurring from low to medium resolution. Although the monotonic signal is often from the low resolution simulations toward atmospheric analyses, in some cases it continues beyond the analyses at the highest resolution. Where convergence occurs, it is not always to the atmospheric analyses, and the highest resolution simulations are not the best by all measures. Although many climate statistics converge, the processes that maintain the climate do not, especially when considered on a regional basis. The implication is that the finer scales are required to capture the nonlinear processes that force the medium scales. Overall, it appears that, at a minimum, T42 resolution is required, but higher resolution would be better. Applications at T42 should take into consideration how model errors indicated by these resolution signals might affect any findings. © 1995 Springer-Verlag."
"7006518289;7005965757;","Cloud albedo feedback and the super greenhouse effect in a global coupled GCM",1995,"10.1007/BF00209514","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029542789&doi=10.1007%2fBF00209514&partnerID=40&md5=f8963871e3b3a6c4b30d75a83670228b","Two competing cloud-radiative feedbacks identified in previous studies i.e., cloud albedo feedback and the super greenhouse effect, are examined in a sensitivity study with a global coupled ocean-atmosphere general circulation model. Cloud albedo feedback is strengthened in a sensitivity experiment by lowering the sea-surface temperature (SST) threshold in the specified cloud albedo feedback scheme. This simple parameterization requires coincident warm SSTs and deep convection for upper-level cloud albedos to increase. The enhanced cloud albedo feedback in the sensitivity experiment results in decreased maximum values of SST and cooler surface temperatures over most areas of the planet. There is also a cooling of the tropical troposphere with attendant global changes of atmospheric circulation reminiscent of those observed during La Niña or cold events in the Southern Oscillation. The strengthening of the cloud albedo feedback only occurs over warm tropical oceans (e.g., the western Pacific warm pool), where there is increased albedo, decreased absorbed solar radiation at the surface, stronger surface westerlies, enhanced westward currents, lower temperatures, and decreased precipitation and evaporation. However, the weakened convection over the tropical western Pacific Ocean alters the large-scale circulation in the tropics such that there is increased upper-level divergence over tropical land areas and the tropical Indian Ocean. This results in increased precipitation in those regions and intensified monsoonal regimes. The enhanced precipitation over tropical land areas produces increased clouds and albedo and wetter and cooler land surfaces. These additional contributions to decreased absorbed solar input at the surface combine with similar changes over the tropical oceans to produce the global cooling associated with the stronger cloud albedo feedback. Increased low-level moisture convergence and precipitation over the tropical Indian Ocean enhance slightly the super greenhouse effect there. But the stronger cloud albedo feedback is still the dominant effect, although cooling of SSTs in that region is less than in the tropical western Pacific Ocean. The sensitivity experiment demonstrates how a regional change of radiative forcing is quickly transmitted globally through a combination of radiative and dynamical processes in the coupled model. This study points to the uncertainties involved with the parameterization of cloud albedo and the major implications of such parameterizations concerning the maximum values of SST, global climate sensitivity, and climate change. © 1995 Springer-Verlag."
"7405429767;7005413744;6701715507;7005533663;","The impact of implementing the bare essentials of surface transfer land surface scheme into the BMRC GCM",1995,"10.1007/BF00211680","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029479295&doi=10.1007%2fBF00211680&partnerID=40&md5=0ee644ae65c39a6899bd2fa92684bb00","This study describes the first order impacts of incorporating a complex land-surface scheme, the bare essentials of surface transfer (BEST), into the Australian Bureau of Meteorology Research Centre (BMRC) global atmospheric general circulation model (GCM). Land seasonal climatologies averaged over the last six years of integrations after equilibrium from the GCM with BEST and without BEST (the control) are compared. The modeled results are evaluated with comprehensive sources of data, including the layer-cloud climatologies from the international satellite cloud climatology project (ISCCP) data from 1983 to 1991 and the surface-observed global data of Warren et al., a five-year climatology of surface albedo estimated from earth radiation budget experiment (ERBE) top-of-the-atmosphere (TOA) radiatioe fluxes, global grid point datasets of precipitation, and the climatological analyses of surface evaporation and albedo. Emphasis is placed on the surface evaluation of simulations of landsurface conditions such as surface roughness, surface albedo and the surface wetness factor, and on their effects on surface evaporation, precipitation, layer-cloud and surface temperature. The improvements due to the inclusion of BEST are: a realistic geographical distribution of surface roughness, a decrease in surface albedo over areas with seasonal snow cover, and an increase in surface albedo over snow-free land. The simulated reduction in surface evaporation due, in part, to the biophysical control of vegetation, is also consistent with the previous studies. Since the control climate has a dry bias, the overall simulations from the GCM with BEST are degraded, except for significant improvements for the northern winter hemisphere because of the realistic vegetation-masking effects. The implications of our results for synergistic developments of other aspects of model parameterization schemes such as boundary layer dynamics, clouds, convection and rainfall are discussed. © 1995 Springer-Verlag."
"7003679645;7006577693;7201394533;17341093800;","The CSIRO nine-level atmospheric general circulation model and its equilibrium present and doubled CO2 climates",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001596985&partnerID=40&md5=d4a9603b7f170f07beead09a51470322","The CSIRO nine-level atmospheric general circulation model is described. Due to the use of the flux form of the dynamical equations, the model achieves conservation of mass and global energy making it particularly suitable for climate simulation. Climatologies of 30-year equilibrium simulations by the model, when coupled to a mixed-layer ocean with prescribed heat transport, for present and doubled CO2 conditions are presented. The global means of standard fields in the simulated present climate are generally close to observed values. Root mean square errors of the fields are tabulated. The spatial and seasonal variations of the fields are simulated with an accuracy comparable to that of other models. A strong spatial correlation between simulated cloud cover and soil moisture is also noted. The global mean surface warming induced by the doubling of CO2 in the model is 4.8°C. The close energy balance of the model ensures that the warming is not affected by any spurious energy sources or sinks. Changes to the structure of standard fields are generally similar to those in simulations previously reported. In the tropics there is a shift upwards of the mean meridional circulation. This is related to changes in the atmospheric diabatic heating rates. The mean level of latent heating rises about 30 hPa. There is also a shift poleward of the latitudes of peak ascent and precipitation associated with the Hadley circulation. However, changes in zonal mean relative humidities are generally small."
"55886067800;7006393267;7101899854;","A reliable and efficient two-stream algorithm for spherical radiative transfer: Documentation of accuracy in realistic layered media",1995,"10.1007/BF00696577","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028990712&doi=10.1007%2fBF00696577&partnerID=40&md5=d01421cfeb92d3f1b3dad07b8f20a2d1","We present a fast and well documented two-stream algorithm for radiative transfer and particle transport in vertically inhomogeneous, layered media. The physical processes considered are internal production (emission), scattering, absorption, and Lambertian reflection at the lower boundary. The medium may be forced by internal sources as well as by parallel or uniform incidence at the top boundary. This two-stream algorithm is based on a general purpose multi-stream discrete ordinate algorithm released previously. It incorporates all the advanced features of this well-tested and unconditionally stable algorithm, and includes two new features: (i) corrections for spherical geometry, and (ii) an efficient treatment of internal sources that vary rapidly with depth. It may be used to compute fluxes, flux divergences and mean intensities (actinic fluxes) at any depth in the medium. We have used the numerical code to investigate the accuracy of the two-stream approximation in vertically inhomogeneous media. In particular, computations of photodissociation and warming/cooling rates and surface fluxes of ultraviolet and visible radiation for clear, cloudy and aerosol-loaded atmospheres are presented and compared with results from multi-stream computations. The O3 +hv → O(1D) + O2 and O3 +hv → O(3P) + O2 photodissociation rates were considered for solar zenith angles between 0.0-70.0° and surface albedos in the range 0.0-1.0. For small and moderate values of the solar zenith angle and the surface albedo the error made by the two-stream approximation is generally smaller, &lt;10%, than the combined uncertainty in cross sections and quantum yields. Surface ultraviolet and visible fluxes were calculated for the same range of solar zenith angles and surface albedos as the photodissociation rates. It was found that surface ultraviolet and visible fluxes may be calculated by the two-stream approximation with 10% error or less for solar zenith angles less than 60.0° and surface albedos less than 0.5. For large solar zenith angles and/or large surface albedos, conditions typical at high latitudes, the error made by the two-stream approximation may become appreciable, i.e. 20% or more for the photodissociation rates in the lower stratosphere and for ultraviolet and visible surface fluxes for large surface albedos. The two-stream approximation agrees well with multi-stream results for computation of warming/cooling rates except for layers containing cloud and aerosol particles where errors up to 10% may occur. The numerical code provides a fast, well-tested and robust two-stream radiative transfer program that can be used as a 'software tool' by aeronomers, atmospheric physicists and chemists, climate modellers, meteorologists, photobiologists and others concerned with radiation or particle transport problems. Copies of the FORTRAN77 program are available to interested users. © 1995 Kluwer Academic Publishers."
"7003798828;6506569634;6701576563;7801416198;7004919386;7202731314;","A Holocene record of climate change, fire ecology and human activity from montane Flat Top Bog, Maui",1995,"10.1007/BF00682765","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028981487&doi=10.1007%2fBF00682765&partnerID=40&md5=c66f00a818193d7e34748fb897c93071","A sediment core from a high-elevation bog on Maui in the Hawaiian Islands contains evidence for drier conditions between 9.4-5.8 kyr BP, followed by a wetter interval between 5.8-2.2 kyr BP, and a variable late Holocene. These precipitation changes may be a reflection of vertical displacements of the upper boundary of the mid-Pacific Trade Wind Inversion (TWI) cloud layer. Fires, probably volcanically ignited, occurred in the forests prior to human arrival. Polynesian activity in this high-elevation, remote site was apparently limited, with no pollen, charcoal, or sedimentological evidence for local anthropogenic disturbance. After European contact, grass fires increased and introduced plant species invaded the site. Values for Cd, Cu, Pb, and Zn in sediments throughout the Holocene indicate low trace-metal deposition from atmospheric particulates at the site, even in the twentieth century. © 1995 Kluwer Academic Publishers."
"7202048112;7003666669;","A subgrid parameterization of orographic precipitation",1995,"10.1007/BF00865510","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029434180&doi=10.1007%2fBF00865510&partnerID=40&md5=bc3f5743c246c8a0a5fc3ba2804657ed","Estimates of the impact of global climate change on land surface hydrology require climate information on spatial scales far smaller than those explicitly resolved by global climate models of today and the foreseeable future. To bridge the gap between what is required and what is resolved, we propose a subgrid-scale parameterization of the influence of topography on clouds, precipitation, and land surface hydrology. The parameterization represents subgrid variations in surface elevation in terms of probability distributions of discrete elevation classes. Separate cloud, radiative, and surface processes are calculated for each elevation class. Rainshadow effects are not treated by the parameterization; they have to be explicitly resolved by the host model. The simulated surface temperature, precipitation, and snow cover for each elevation class are distributed to different geographical locations according to the spatial distribution of surface elevation within each grid cell. The subgrid parameterization has been implemented in the Pacific Northwest Laboratory's climate version of the Penn State/NCAR Mesoscale Model. The scheme is evaluated by driving the regional climate model with observed lateral boundary conditions for the Pacific Northwest and comparing simulated fields with surface observations. The method yields more realistic spatial distributions of precipitation and snow cover in mountainous areas and is considerably more computationally efficient than achieving high resolution by the use of nesting in the regional climate model. © 1995 Springer-Verlag."
"56985140700;6602264002;6602252314;","The impact of horizontal resolution on moist processes in the ECMWF model",1995,"10.1007/BF00211675","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028975173&doi=10.1007%2fBF00211675&partnerID=40&md5=2d2ae2fc38a19913358aaf330bd63e76","Summer and winter climates simulated with the ECMWF (cycle 33) model at spectral scales T21, T42, T63 and T106 are analyzed to determine the impact of changes in horizontal resolution on atmospheric water vapor, clouds, convection, and precipitation. Qualitative changes in many moist processes occur in the transition from T21 to T42, especially in the tropics; at higher resolutions mostly incremental variations from patterns established at T42 result. Large-scale tropical moist processes are simulated more realistically at T21 than at finer resolutions, possibly reflecting a mismatch between the finer-scale dynamics and the scales at which the underlying assumptions of the physical parameterizations apply. Global precipitation increases monotonically with resolution, as a consequence of increasing convection. Global cloud cover, however, decreases in the transition from T21 to T42 due to drying of the tropics, but then increases slightly at finer resolutions. These small global increases are an outcome of compensating changes in different regions: decreases in cloud cover due to drying of the atmosphere at low latitudes are offset by high-latitude increases resulting from enhanced relative humidity associated with an intensifying atmospheric cold bias at finer resolutions. © 1995 Springer-Verlag."
"6507518078;7006282106;6602193004;16404195400;7003297944;7004299063;6603061620;","Potential effects of global climatic change on the phenology and yield of maize in venezuela",1995,"10.1007/BF01094016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028977701&doi=10.1007%2fBF01094016&partnerID=40&md5=933769d979d489de4bda165db727805c","Simulated impacts of global and regional climate change, induced by an enhanced greenhouse effect and by Amazonian deforestation, on the phenology and yield of two grain corn cultivars in Venezuela (CENIAP PB-8 and OBREGON) are reported. Three sites were selected:Turén, Barinas and Yaritagua, representing two important agricultural regions in the country. The CERES-Maize model, a mechanistic process-based model, in the Decision Support System for Agrotechnology Transfer (DSSAT) was used for the crop simulations. These simulations assume non-limiting nutrients, no pest damage and no damage from excess water; therefore, the results indicate only the difference between baseline and perturbed climatic conditions, when other conditions remain the same. Four greenhouse-induced global climate change scenarios, covering different sensitivity levels, and one deforestation-induced regional climate change scenario were used. The greenhouse scenarios assume increased air temperature, increased rainfall and decreased incoming solar radiation, as derived from atmospheric GCMs for doubled CO2 conditions. The deforestation scenarios assume increased air temperature, increased incoming solar radiation and decreased rainfall, as predicted by coupled atmosphere-biosphere models for extensive deforestation of a portion of the Amazon basin. Two baseline climate years for each site were selected, one year with average precipitation and another with lower than average rainfall. Scenarios associated with the greenhouse effect cause a decrease in yield of both cultivars at all three sites, while the deforestation scenarios produce small changes. Sensitivity tests revealed the reasons for these responses. Increasing temperatures, especially daily maximum temperatures, reduce yield by reducing the duration of the phenological phases of both cultivars, as expected from CERES-Maize. The reduction of the duration of the kernel filling phase has the largest effect on yield. Increases of precipitation associated with greenhouse warming have no effects on yield, because these sites already have adequate precipitation; however, the crop model used here does not simulate potential negative effects of excess water, which could have important consequences in terms of soil erosion and nutrient leaching. Increases in solar radiation increased yields, according to the non-saturating light response of the photosynthesis rate of a C4 plant like corn, compensating for reduced yields from increased temperatures in deforestation scenarios. In the greenhouse scenarios, reduced insolation (due to increased cloud cover) and increased temperatures combine to reduce yields; a combination of temperature increase with a reduction in solar radiation produces fewer and lighter kernels. © 1995 Kluwer Academic Publishers."
"7006393267;7005892627;7401773666;","The Atmospheric Radiation Measurements (ARM) program: ARM's window on the Arctic",1995,"10.1016/0048-9697(95)04415-W","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028888228&doi=10.1016%2f0048-9697%2895%2904415-W&partnerID=40&md5=570e1b448cab872793cf2ed87f5fa872","A 'blue ribbon' committee established by the U.S. National Academy of Sciences has stated that uncertainties associated with cloud behavior constitute the major obstacle to progress in climate modeling and prediction. The Atmospheric Radiation Measurements (ARM) Program is a 10-year climate research program aimed at unravelling the role of clouds in the climate system. The focus is on studying the life cycle of clouds and the effects of clouds on high-latitude ARM site. Global climate models appear to be particularly sensitive to climate perturbations at high latitudes. Of course, climate changes have profound effects on the ecology. One objective is to design a research program that will enable us to investigate the relationship between arctic clouds and anthropogenic pollution transported to the north from lower latitudes. The Arctic is also characterized by extreme seasonal variation in insolation, surface properties, and exchange of water vapor between the surface and the atmosphere. This extreme variation leads to important climate feedback mechanisms involving the interaction between surface temperature and water vapor, cloud cover, and surface albedo. The challenge for the Alaskan ARM site is to capture these high-latitude feedback processes for inclusion in global climate models. To put possible climate changes into perspective, we note that the 'Little Ice Age', which ended the pre-Columbian Icelandic colony in Greenland and probably prevented permanent settlements in Vinland (i.e. North America), represented an average decrease of only about 2-3°C. © 1995 Elsevier Science B.V. All rights reserved."
"7202162685;","Interactions among aerosols, clouds, and climate of the Arctic Ocean",1995,"10.1016/0048-9697(95)04411-S","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028977053&doi=10.1016%2f0048-9697%2895%2904411-S&partnerID=40&md5=11393f7f4a1015dd5c20dd7708d39ba1","Considerable interest has recently been generated by the suggestion that the direct and indirect radiative effects of aerosols in the troposphere may be sufficient on a global basis to offset the radiative effects of increasing greenhouse gases. This paper focuses on understanding these relationships in the Arctic, which are of particular complexity because of the high surface albedo in the Arctic; the marked annual cycle of arctic aerosol characteristics; the extreme static stability of the arctic lower troposphere; dependence of arctic cloud infrared emissivities on drop size distribution and aerosol characteristics; sensitivity of ice nucleation to aerosols; complex radiative interactions occurring between aerosols, clouds, and sea ice; the annual cycle of aerosol residence time in the Arctic; and the impact of aerosol perturbations on the meridional heat transport to the Arctic. © 1995 Elsevier Science B.V. All rights reserved."
"7201361035;","Inference of the climatic efficiency of clouds from satellite measurements",1995,"10.1080/01431169508954598","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029513129&doi=10.1080%2f01431169508954598&partnerID=40&md5=0e86c6720442a0792b60ee895dd197c8","The influence of clouds over the North Sea on the radiation field and on climate is investigated by analysing satellite measurements. The main interest is on high clouds due to their ambivalent behaviour in the radiation field. To quantify the influence of clouds on climate, the cloud-climate efficiency is introduced. The cloud-climate efficiency allows us to estimate the gain or respectively loss of energy of the earth/atmosphere system in the presence of a cloud, which can be specified by a cloud classification. The spatial integration of the cloud-climate efficiencies results in the cloud forcing defined by the difference of the radiative fluxes within a clear sky and a cloudy satellite image pixel. The first step is an accurate detailed cloud classification based on the maximum likelihood method. The method developed for National Oceanograph and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA AVHRR) data and Meteosat data can be used to discriminate 24 clouds, especially high clouds with different optical depths. Evaluating these results, a good agreement between the cloud types inferred from satellite data and from synoptical observations could be achieved. In the following step transmittances of high clouds could be determined by using NOAA AVHRR data, where for the solar spectrum a simple radiative transfer scheme is applied. For the longwave spectrum, an equation after Platt is used. Comparing these transmittances with groand based observations during field experiments (ICE’87, ICE’89. IGPB’90), good agreements could be foand. Using NOAA AVHRR data, the derived information is applied to compute the cloud-climate efficiency at the top of the atmosphere. It can be seen that in the shortwave spectrum the cloud-climate efficiency shows a general cooling effect of the earth/atmosphere system for all clouds and a strong dependence on the insolation. Regarding the cloud-climate efficiency in the longwave spectrum, a heating of the earth/atmosphere system due to clouds was always observed. Thus, high clouds with the same optical properties may lead to different effects in the earth/atmosphere system depending on the anderlying surface, on the optical depths of that cloud, and on the geographical appearance related to the insolation. An approach to compare the increasing cloud forcing at the top of the atmosphere with an analysis of the relative topography 300/850 hPa shows that the increase of the cloud forcing is well correlated with an increase of the temperature in this layer. © 1995 Taylor & Francis Group, LLC."
"7003869084;7004604556;","Cloud feedback examined using a two-component time-dependent climate model",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028806844&partnerID=40&md5=e6a49b391351edfe70e0651c06021815","A zero-dimensional, time-dependent, two-component atmosphere-ocean climate model shows that water vapor and snow-ice albedo feedbacks may lead to multiple stable equilibria. A sensitivity study shows that depending on the rate of change of cloud infrared emissivity and cloud albedo with temperature, several regimes with differing stability characteristics may be identified. In the model, the cloud water content and cloud altitude feedbacks, coupled with enhanced greenhouse longwave forcing, lead to the formation of a new warm stable equilibrium. In a time-dependent simulation with a single layer ocean, the global mean surface temperature rises gradually, then rapidly, finally reaching a value approximately 14 K warmer than at present, when an enhanced greenhouse flux of 4 Wm-2 is added. -Authors"
"7201361035;","The variability of cloud cover and cloud forcing inferred from NOAA AVHRR data for the North Sea",1995,"10.1016/0273-1177(95)00376-P","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028808424&doi=10.1016%2f0273-1177%2895%2900376-P&partnerID=40&md5=f96856b7313d01cfd75a46290fee9d34","From August 1990 until September 1994, NOAA AVHRR HRPT data were analysed to determine the variability of cloud cover and of cloud forcing at top of atmosphere (TOA) for the North Sea (1300×1300 km2). The first step was a detailed cloud classification based on the maximum likelihood method. That classification scheme allows a discrimination of 24 cloud classes, especially high clouds with different optical properties. The validation of these results is based on synoptical observations. Therefore, the annual variability of cloud cover can be shown for individual synoptical ground stations and for larger areas inferred from satellite data. Due to an overlapping period with ISCCP C2 data, a comparison with the high-resolution results was carried out. That led to a 10 year cloud cover climatology (1983-1993) for the North Sea, where 24 grid areas (each 2.5°×2.5°) could be investigated. A further step is the computation of cloud-climate efficiency and cloud forcing at top of atmosphere, where cloud forcing is the area mean of cloud-climate efficiencies. The cloud-climate efficiency is the cloud forcing of an individual classified cloud. For the analysed period, the variability of cloud forcing depends strongly on the cloud cover variability. Thus, the drought 1992 in Schleswig-Holstein and in northern Germany can be detected and the influence of high clouds, their amplifying heating effect, can be shown. © 1995."
"7005513582;7005814217;55745955800;7005070958;","Sensitivity of a GCM climate to enhanced shortwave cloud absorption",1995,"10.1175/1520-0442(1995)008<2200:SOAGCT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029480675&doi=10.1175%2f1520-0442%281995%29008%3c2200%3aSOAGCT%3e2.0.CO%3b2&partnerID=40&md5=db48eaa39d675bbb4e679b1073f38e14","Recent studies by Cess et al. and Ramanathan et al. find that clouds absorb significantly more shortwave radiation than currently modeled by general circulation models. Initial calculations for the global annual shortwave energy budget imply that including the additional shortwave cloud absorption leads to an additional 22 W m-2 absorption in the atmosphere, with an equivalent reduction of shortwave flux at the surface. The present study investigates the climate implications of enhanced cloud absorption with the use of the National Center for Atmospheric Research Community Climate Model. The GCM response to this forcing is to warm the upper troposphere by as much as 4 K. -from Authors"
"57203053317;7003979342;","Influence of cirrus cloud radiative forcing on climate and climate sensitivity in a general circulation model",1995,"10.1029/95jd01383","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2342445509&doi=10.1029%2f95jd01383&partnerID=40&md5=61617d0c421ab7767ea00bc108d82768","Six numerical experiments have been performed with a general circulation model (GCM) to study the influence of high-level cirrus clouds and global sea surface temperature (SST) perturbations on climate and climate sensitivity. The model is able to reproduce many features of the observed cloud radiative forcing with considerable skill, such as the annual mean distribution, the response to seasonal forcing, and the response to SST variations in the equatorial Pacific. In addition to a reference experiment where the cirrus emissivity is computed as a function of the cloud water content, two sensitivity experiments have been performed. These three experiments are repeated identically, except for prescribing a globally uniform SST warming of 4 K. -from Authors"
"57203200427;","GCM estimate of the indirect aerosol forcing using satellite- retrieved cloud droplet effective radii",1995,"10.1175/1520-0442(1995)008<1403:GEOTIA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029507078&doi=10.1175%2f1520-0442%281995%29008%3c1403%3aGEOTIA%3e2.0.CO%3b2&partnerID=40&md5=f23dae97dd9573a17d316bd8450d1767","In a recent paper, Han et al. analyzed satellite data radiances to retrieve cloud droplet effective radi and reported significant interhemispheric differences for both maritime and continental clouds. The mean cloud droplet radius in the Northern Hemisphere is smaller than in the Southern Hemisphere by about 0.7 μm. This hemispheric contrast suggests the presence of an aerosol effect on cloud droplet size and is consistent with higher cloud condensation nuclei number concentration in the Northern Hemisphere due to anthropogenic production of aerosol precursors. In the present study, we constrain a climate model with the satellite retrievals of Han et al. and discuss the climate forcing that can be inferred from the observed distribution of cloud droplet radius. -from Author"
"7403364976;","Comparison of the surface solar radiation budget derived from satellite data with that simulated by the NCAR CCM2",1995,"10.1175/1520-0442(1995)008<2824:COTSSR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029434297&doi=10.1175%2f1520-0442%281995%29008%3c2824%3aCOTSSR%3e2.0.CO%3b2&partnerID=40&md5=23468be99335b4f653c8408f2d61d7b3","A comparison of the monthly mean shortwave surface radiation budget (SRB) obtained from the World Climate Research Program (WCRP) shortwave global dataset with that simulated by the National Center for Atmopsheric Research Community Climate Model version 2.0 (CCM2) is presented. WCRP/SRB data are derived from the International Satellite Cloud Climatology Project (ISCCP) C1 data using the Pinker algorithm. The largest discrepancies are found in the summer midlatitude regions where CCM2 overestimates surface solar fluxes relative to Pinker by as much as 100 W m-2. Most of the differences are associated with deficiencies in CCM2's prediction of cloud optical properties and cloud amount."
"6602418886;7403364976;7202155374;","Land surface temperature and radiative fluxes response of the NCAR CCM2/biosphere-atmosphere transfer scheme to modifications in the optical properties of clouds",1995,"10.1029/95jd02375","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029479830&doi=10.1029%2f95jd02375&partnerID=40&md5=b0334621621d461d2a6cf95d008d662d","Climate simulations of the National Center for Atmospheric Research (NCAR) community climate model version 2 (CCM2) are compared with several data sets. These data sets are a multiyear climatology of the Earth Radiation Budget Experiment (ERBE) top-of-the-atmosphere (TOA) radiative fluxes, the International Satellite Cloud Climatology Prolject (ISCCP) cloudiness, and the Surface Radiation Budget (SRB) Project surface insolation. The comparison focuses on global and regional spatial scales and the seasonal timescale. A revised computational scheme of the cloud optical properites is introduced in the solar and longwave radiative transfer parameterizations of CCM2. -from Authors"
"35461255500;57193897609;7006712143;7005755464;","Changes in cloud properties due to NOx emissions",1995,"10.1029/94GL02691","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029105043&doi=10.1029%2f94GL02691&partnerID=40&md5=f07164db586a179e147bca1e64eb6d49","Climate forcing by anthropogenic aerosols has recently excited growing interest [Charlson et al., 1987; Charlson et al., 1990; Wigley, 1991; Charlson et al., 1992]. It has earlier been shown that increased cloud droplet concentrations can increase cloud albedos [e.g. Twomey et al., 1984]. Wigley [1991] and Charlson et al. [1990] have pointed out that the Northern Hemisphere may be warming more slowly than the Southern Hemisphere. According to them this is mainly due to the direct and indirect effects of sulphate aerosols. In this report we discuss an alternative mechanism which could enhance indirect climate forcing by aerosols. Increased concentrations of condensable vapours (such as HNO3 and HCl) in the atmosphere could activate an increased number of pre‐existing aerosol particles to act as cloud condensation nuclei [Kulmala et al., 1993]. This would cause similar effects on optical properties of clouds as an increase of aerosol particles in the atmosphere. Copyright 1995 by the American Geophysical Union."
"7004325649;7005070958;35468686100;7202208382;7201635744;","Mission to Planet Earth: role of clouds and radiation in climate",1995,"10.1175/1520-0477(1995)076<2125:mtpero>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029472834&doi=10.1175%2f1520-0477%281995%29076%3c2125%3amtpero%3e2.0.co%3b2&partnerID=40&md5=a4991c274b7be8ec316d5a9fe70d453e","This paper presents an overview of the role of the National Aeronautics and Space Administration's Earth Observing System (EOS) satellite data in understanding the role of clouds in the global climate system. The paper gives a brief summary of the cloud/radiation problem, and discusses the critical observations needed to support further investigations. The planned EOS data products are summarized, including the critical advances over current satellite cloud and radiation budget data. Key advances include simultaneous observation of radiation budget and cloud properties, additional information on cloud particle size and phase, improved detection of thin clouds and multilayer cloud systems, greatly reduced ambiguity in partially cloud-filled satellite fields of view, improved calibration and stability of satellite-observed radiances, and improved estimates of radiative fluxes at the top of the atmosphere, at the surface, and at levels within the atmosphere. -from Authors"
"7409522591;7005453346;","Role of convective scale momentum transport in climate simulation",1995,"10.1029/94JD02519","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028977718&doi=10.1029%2f94JD02519&partnerID=40&md5=331f923f162e9a6f2a5947540ec15c33","A unique feature of the scheme is the inclusion of the perturbation pressure field induced by convection and its effect on the cloud momentum transport. Through two experiments of seasonal simulations, it is shown that the perturbation pressure forcing on the cloud momentum transport accounts for a significant part of the total convective momentum source/sink, indicating that the cloud momentum field is substantially modulated by the convection-induced pressure field. The overall effect of convective momentum transport is to reduce the vertical wind shear in both the zonal and the meridional directions. The response of the large-scale circulation to convective momentum transport is very significant. -from Authors"
"7409537515;7005070958;7409810937;","Effects of longwave cloud radiative forcing anomalies on the atmospheric response to equatorial Pacific sea surface temperature anomalies",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029531522&partnerID=40&md5=8d4b42709ba094e0e08e8cd9745a77a7","The latest version of the National Center for Atmospheric Research community climate model (CCM2) has been used to investigate cloud radiative forcing (CRF) anomalies associated with equatorial Pacific sea surface temperature (SST) anomalies and the effects of the longwave CRF (LWCRF) anomalies on the atmospheric response to the SST anomalies. The relative magnitude of the simulated longwave and shortwave CRF anomalies is consistent with the result of the Earth Radiation Budget Experiment (ERBE), implying that cloud height and cloud radiative properties such as emissivity and reflectivity are well simulated by the model. -from Authors"
"7006494557;7101846835;","Comparison of simulated cloud cover with satellite observations over the western United States",1995,"10.1175/1520-0442(1995)008<0296:COSCCW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029503585&doi=10.1175%2f1520-0442%281995%29008%3c0296%3aCOSCCW%3e2.0.CO%3b2&partnerID=40&md5=666d97b2f798cc5f1ee07083d8da6868","Satellite image datasets and regional climate model results are intercompared for evaluation of model accuracy in the simulation of cloud cover. Both monthly average and individual simulation times are analyzed. To provide a consistent comparison, satellite data are first mapped into the model's geographic projection, grid domain, and resolution. Correlations between the spatial distributions of model-derived and observed cloud fractions are found to exceed 0.80 for certain geographic regions of the West, and these correlations are largest over mountainous areas during summer. Case studies of a series of daily cloud cover demonstrate the ability of the model to simulate the effects of frontal passage on cloud distribution. -from Authors"
"25941200000;","Methodological dependencies of cloud radiative forcing for the Canadian Climate Centre second-generation general circulation model",1995,"10.1029/94JD02045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028885476&doi=10.1029%2f94JD02045&partnerID=40&md5=79c5e0bbc63543b42a527756e0268ab3","Clear-sky fluxes at the top of the atmosphere (TOA) are essential for calculating cloud radiative forcings (CRF). Both sets of quantities have been computed by three different methods using data from the Canadian Climate Centre general circulation model (CCC-GCM) (simulations of July 1985 and January 1986). The methods differ in the way they compute monthly mean clear-sky fluxes at the TOA (F̄c). The first method, known as method 2, is ideal for intercomparing GCMs, but does not sample clear skies as satellites do. The other two methods compute F̄c by avoiding days with minimum and average cloud amounts that exceed a threshold. These methods are referred to a method 3 and 4, respectively. The geographic distributions and magnitudes of LW CRF differences between method 4 and method 2 resemble strongly corresponding fields for the ECMWF and the NCAR community climate model 2 GCMs. -from Author"
"56896217400;26643036500;","Subjective Judgments by Climate Experts",1995,"10.1021/es00010a003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029128396&doi=10.1021%2fes00010a003&partnerID=40&md5=28ac13bd594e9d54774c1fc1f1166c57","Structured interviews using “expert elicitation” methods drawn from decision analysis were conducted with 16 leading U.S. climate scientists. We obtained quantitative, probabilistic judgments about a number of key climate variables and about the nature of the climate system. We also obtained judgments about the relative contributions of various factors to the uncertainty in climate sensitivity, We found strong support for the importance of convection/ water vapor feedback and of cloud optical properties. A variety of questions were posed to elicit judgments about future research needs and the possible sources and magnitude of future surprises. The results reveal a rich diversity of expert opinion and, aside from climate sensitivity, a greater degree of disagreement than is often conveyed in scientific consensus documents, Research can make valuable contributions, but we interpret our results to mean that overall uncertainty about the geophysics of climate change is not likely to be reduced dramatically in the next few decades. © 1995, American Chemical Society. All rights reserved."
"7005171879;","The 5-6 December 1991 FIRE IFO II jet stream cirrus case study: possible influences of volcanic aerosols",1995,"10.1175/1520-0469(1995)052<0097:TDFIIJ>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028975339&doi=10.1175%2f1520-0469%281995%29052%3c0097%3aTDFIIJ%3e2.0.CO%3b2&partnerID=40&md5=eeb355c8baaefc14d9b150fdbe137315","Following the local appearance of a spur of stratospheric volcanic debris from the subtropics, a series of jet streams subsequently conditioned the troposphere through tropopause foldings with sulfur-based particles that became effective cloud-forming nuclei in cirrus clouds. Aerosol and ozone measurements suggest a complicated history of stratospheric-tropospheric exchanges embedded within the upper-level flow, and cirrus cloud formation was noted to occur locally at the boundaries of stratospheric aerosol-enriched layers that became humidified through diffusion, precipitation, or advective processes. Apparent cirrus cloud alterations include abnormally high ice crystal concentrations (up to ~600 L-1, complex radial ice crystal types, and relatively large haze particles in cirrus uncinus cell heads at temperatures between -40° and -50°C. Implications for volcanic-cirrus cloud climate effects and usual (nonvolcanic aerosol) jet stream cirrus cloud formation are discussed. -from Authors"
"7004061048;7006083502;","Atmospheric planetary boundary‐layer research in the U.S.: 1991–1994",1995,"10.1029/95RG00185","https://www.scopus.com/inward/record.uri?eid=2-s2.0-11744280292&doi=10.1029%2f95RG00185&partnerID=40&md5=ba3f2e1475a713e9143b0275f2098d6d","With the increasing emphasis on coupled climate systems, planetary‐boundary‐layer (PBL) research has also gained increasing attention. Atmospheric and oceanic PBLs serve as the interface between all of the system components: atmosphere, ocean, land, and biosphere. Boundary‐layer clouds also play important roles in climate, e.g., trade‐wind cumulus in the hydrological cycle and subtropical marine stratus in the Earth's radiation budget. Therefore, proper PBL parameterization schemes are needed to accurately link all of the climate system components and to represent cloud formation and dissipation. Copyright 1995 by the American Geophysical Union."
"35557549500;","Ice crystals in high clouds and contrails",1995,"10.1016/0169-8095(94)00096-V","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029528540&doi=10.1016%2f0169-8095%2894%2900096-V&partnerID=40&md5=22c1e8209dc19ae28b774a5f01e343c3","In honor of Dr. Helmut K. Weickmann's lifetime achievements, some of his early discoveries on ice crystals in high clouds are resurrected and discussed. It is demonstrated that the shapes and sizes of cloud meteors convey information related to cloud type, cloud duration, cloud amount, cloud radiative forcing, and the environment in which the cloud forms. For example, persistence of a contrail behind an aircraft depends on ice crystal concentration and size distribution, which are governed by the ambient temperature, humidity, and the concentration of ice nuclei. It is suggested that increased air traffic, especially high-flying jets over the past three decades, may have modified global cirrus cloud amount, which in turn may affect surface temperature and global climate. © 1995."
"7004198777;35465220500;7004775578;7006307463;","Effects of aerosol particles on the microphysics of coastal stratiform clouds",1995,"10.1175/1520-0442(1995)008<0773:EOAPOT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029474559&doi=10.1175%2f1520-0442%281995%29008%3c0773%3aEOAPOT%3e2.0.CO%3b2&partnerID=40&md5=29a7f59f89307eca61ec5ac2b29566d4","Aerosol particles can act as cloud condensation nuclei and thereby influence the number and size of droplets in clouds. Consequently, anthropogenic particles have the potential to influence global climate by increasing cloud albedo and decreasing precipitation efficiencies. Enhanced cloud reflectances associated with increases in particle number have been observed, but our understanding of these interactions has been hindered by incomplete empirical studies and models of limited scope. In this study, aerosol and droplet size distributions were measured on 13 research flights in stratiform clouds within 300 km west of the northern California coast. The chemical composition of the droplet solute was also assessed. -from Authors"
"6603896143;","Urban climate studies in Israel-A review",1995,"10.1016/1352-2310(94)00277-R","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028973709&doi=10.1016%2f1352-2310%2894%2900277-R&partnerID=40&md5=fd9d56c219be59241adcf19091103295","The paper summarizes three decades of urban climate studies in Israel. These studies focused on heat islands in various towns and the effect of urbanization on rainfall excesses over cities and their downwind areas. While the magnitude of these phenomena and their spatial distribution are not at variance with tropical and extra-tropical urban climate literature, the explanation of the dominant cause of urban rainfall excess in Israel contributes to our understanding of the problem in general. There is some support to the notion that the heat island's thermodynamics combined with the aerodynamic roughness of the urban structure enhances the rainfall rather than air pollution. Another vital contribution of this research lies in the spatial techniques which separate between the effects of enhancement due to cloud seeding operations and inadvertent urban climate modification. © 1995."
"6602627241;7003979342;","Sensitivity of a general circulation model to parameterizations of cloud-turbulence interactions in the atmospheric boundary layer",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028870830&partnerID=40&md5=f85f51ca3541301b9d13b64c081eefb6","Several approaches to parameterize the turbulent transport of momentum, heat, water vapour and cloud water for use in a general circulation model (GCM) have been tested. The basic properties of these parameterizations are discussed first in relation to column simulations of a stratocumulus-topped atmospheric boundary layer (ABL) under a strong subsidence inversion during the KONTROL experiment in the North Sea. Thus, the TKE-scheme provides a better link between the cloud and the sub-cloud layer and also between the cloud and the inversion as a result of cloud-top entrainment. In the stratocumulus case study, increased entrainment favours cloud dilution through enhanced evaporation of cloud droplets. In the GCM study, however, additional cloud-top entrainment supports cloud formation. -from Authors"
"57203200427;57203053317;","The sulfate-CCN-cloud albedo effect: a sensitivity study with two general circulation models",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029476116&partnerID=40&md5=ef90f9fbcd92431110b1087c61311a8a","Aerosol particles, such as sulfate aerosols, can act as cloud condensation nuclei (CCN). The CCN spectrum and the water vapor supply in a cloud determine the cloud droplet number concentration (CDNC) and hence the shortwave optical properties of low-level liquid clouds. The capability of anthropogenic aerosols to increase cloud reflectivity and thereby cool the Earth's surface is referred to as the indirect effect of anthropogenic aerosols. To obtain an estimate of this effect on climate, we empirically relate the CDNC, and thus the cloud optical properties, of two general circulation models (GCM) to the sulfate aerosol mass concentration derived from a chemical transport model. -from Authors"
"7402739097;7202899330;","Entropy and climate. II: Simple models",1995,"10.1002/qj.49712152712","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029510147&doi=10.1002%2fqj.49712152712&partnerID=40&md5=89d394695fcfcb49975e8181b04bd538","The possibility that the climate of planet earth might be a state of maximum dissipation was explored by Paltridge through the development of a simple energy‐balance model of climate. In this paper we examine the assumptions in Paltridge's model and show that the model can be reduced analytically to a model involving trivial numerical computation. This step exposes the interplay of energy balance, dynamics, and extremum principles. In particular, we highlight the role of a secondary extremum‐principle, related to convective activity, which postulates that cloud cover and surface temperature conspire to maximize the sum of sensible‐and latent‐heat fluxes. We show that this convection hypothesis leads to simple algebraic relations (between cloud cover, surface temperature and horizontal convergence of energy) which could be tested against satellite data. We examine a single‐box version of Paltridge's model that exhibits remarkable temperature‐regulation through adjustment of cloud cover, and show that the regulation follows from the convection hypothesis rather than the maximum‐dissipation hypothesis. Next we investigate the relevance to climate of a theorem on maximum dissipation derived by Ziegler. We reconcile the maximum‐ and minimum‐dissipation theorems of Ziegler and Prigogine in the context of a simple model. Finally, we speculate how the principle of maximum dissipation might be applied in a climate model. Copyright © 1995 Royal Meteorological Society"
"7203015939;8204540500;7401823436;","Climate response to indirect anthropogenic sulfate forcing",1995,"10.1029/95GL01660","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029500764&doi=10.1029%2f95GL01660&partnerID=40&md5=144cfd6008f2d7d03b5dbba20cec6ef0","A general circulation model (GCM) has been used to conduct sensitivity tests of the climatic influence imparted by a cloud albedo change hypothesized to result from anthropogenic increases in atmospheric sulfur. The global distribution of anthropogenic sulfate aerosols is computed with a simplified 3‐D transport model. The NCAR CCM1 has been run with a cloud albedo perturbation that is a function of the distribution of anthropogenic sulfur particles. We report climate statistics from the last 20 years of 30 year GCM control and experiment runs. The climate response is strongest in the northern hemisphere winter, with cooling over the North Atlantic and North Pacific oceans on the order of 2–6°C. The 500 mb geopotential height field shows a significant deepening over the Canadian provinces, enhancing the northerly flow over the North American and North Atlantic regions during boreal winter. The equilibrium climate does not, however, cool over central Europe in northern hemisphere winter, despite this region being one of the most heavily impacted areas in the world by sulfate aerosol. The anthropogenic sulfate ‘indirect’ forcing elicits a highly non‐linear climate response that can be explained through changes in the hemispheric wave train. These results may assist in explaining the long‐standing climate change issue of what causes the cooling over the North Atlantic and North Pacific over the last decades, a feature that is not explained by increases in greenhouse gases alone. Copyright 1995 by the American Geophysical Union."
"7005137442;","Thermostats, radiator fins, and the local runaway greenhouse",1995,"10.1175/1520-0469(1995)052<1784:TRFATL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029412925&doi=10.1175%2f1520-0469%281995%29052%3c1784%3aTRFATL%3e2.0.CO%3b2&partnerID=40&md5=553bfd630d91a29a84ec520c31fdada2","The author has reconsidered the question of the regulation of tropical sea surface temperature. This has been done in general terms through consideration of the tropical heat budget and in specific terms through consideration of an idealized radiative-dynamic model of the tropical general circulation. It is argued that evaportion on its own cannot provide an effective regulating mechanism. Clouds cannot serve as regulators unless there are substantial departures from the observed cancellation between cloud greenhouse and cloud albedo effects. It is found that the main determinant of tropical climate is the clear-sky water vapor greenhouse effect averaged over the entire Tropics. In the absence of dry ""radiator fins' maintained by subsidence, the tropical temperature would tend to fall into a runaway greenhouse state that could be stabilized only by heat export to the extratropics. -from Author"
"57212781009;6701715507;","Sensitivity of the climate response of an atmospheric general circulation model to changes in convective parameterization and horizontal resolution",1995,"10.1029/94JD02827","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028837747&doi=10.1029%2f94JD02827&partnerID=40&md5=a5a0591f7d10785873b1ac568cdb3427","Three equilibrium doubled CO2 experiments have been performed using the Bureau of Meteorology Research Centre atmospheric general circulation model. The precipitation distributions agree reasonably with observations overall, although the mass flux scheme gives improvements in some regions. The increase in resolution is generally found to have a smaller impact upon the climate than the change in convection. Under a doubling of atmospheric CO2, the equilibrium responses of all three experiments were extremely similar in surface and tropospheric temperatures and humidity changes. The model response is at the low end of the scale of simulated climate change, consistent with a strong negative feedback found due to clouds. This feedback is similar to that found in earlier fixed season experiments. It appears to be insensitive to differences in cloud cover simulated in the control climates of the present experiments. -Authors"
[No author id available],"Guidelines for cloud seeding to augment precipitation",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041146343&partnerID=40&md5=44309d6f97a253cea56e88b47ad8c9c8","This manual of professional practice, Guidelines for Cloud Seeding to Augment Precipitation (ASCE Manual No. 81), is the outgrowth of a committee report by the same title published by the ASCE Weather Modification Committee in the March 1983 issue of Journal of Irrigation and Drainage Engineering. A task committee of the ASCE Climate and Weathering Change Committee has expanded and updated this report to provide water resources managers and others who might become involved in the decision-making process for implementing a cloud seeding project with the necessary guidelines. -from Author"
"7201653018;7201483914;","Role of radiative transfer in maintenance and destruction of stratocumulus clouds",1995,"10.1016/1352-2310(94)00242-D","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028991265&doi=10.1016%2f1352-2310%2894%2900242-D&partnerID=40&md5=dd6dc2f3b83c7485a5732e02d87f360d","A mesoscale numerical model is used to study the physical processes in the maintenance of a stratocumulus topped boundary layer. The model includes a surface energy budget, closure using a scheme based on the turbulence kinetic energy, a five category cloud physics scheme and radiative transfer. Model results demonstrate the role radiative flux divergence plays in the maintenance of a stratocumulus layer. Radiative heating and cooling of the cloud layer destabilizes the upper boundary layer and decouples that portion of the boundary layer from the surface layer. Eventually, sufficient solar radiation reaches the surface to overcome the decoupling and the cloud layer dissipates. © 1995."
"25953950400;35453054300;","Human impacts on weather and climate",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041146153&partnerID=40&md5=794f231ef4cd1686a33236cd146715e7","As world population grows there is increasing evidence that human activities are having a significant impact on weather and climate, from a local to global scale. This book is a non-mathematical presentation of the basic physical concepts of how human activity may affect our weather and climate. It assesses the current hypotheses and examines whether the impacts are measurable. Included are critical evaluations of the scientific status of weather modification by cloud seeding, human impacts on regional weather and climate, and human impacts on global climate, including the greenhouse gas hypothesis. Also included are discussions of the modern philosophy of science and its application to determining human impacts on weather and climate. -from Publisher"
"7201888941;","A review of theoretical and observational studies in cloud and precipitation physics: 1991–1994",1995,"10.1029/95RG00744","https://www.scopus.com/inward/record.uri?eid=2-s2.0-5344267772&doi=10.1029%2f95RG00744&partnerID=40&md5=9a9bec8eb56bca7d327e9fd57444c306","It is becoming increasingly evident that clouds and precipitation play a critical role in many of the environmental or so‐called “strategic” issues facing our society today, such as the “ozone hole” problem, climate change, ocean‐atmospheric interactions and acid rain. Clouds and precipitation also play an important role in many applied problems such as aircraft icing and short‐term forecasting. Solutions to these and other problems will require a deeper understanding of how clouds form, evolve and impact their surroundings. Scales associated with cloud formation range from the size of a sub‐micron aerosol particle to the scale of a large hurricane. Scientific studies during the last four years have reaffirmed the notion that in order to adequately understand the role of clouds in these strategic and applied problems, fundamental studies on all scales important to cloud formation and evolution are required. Copyright 1995 by the American Geophysical Union."
"6602142887;6602709436;","Diurnal temperature range and cloud cover in the Nordic countries: observed trends and estimates for the future",1995,"10.1016/0169-8095(94)00078-R","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029501584&doi=10.1016%2f0169-8095%2894%2900078-R&partnerID=40&md5=dcb6bd108227a0b9130ed2377643da20","A simple regression model relating local monthly mean diurnal temperature range (DTR) and cloudiness at 10 synoptic stations in the Nordic region to monthly mean large-scale tropospheric flow has been constructed. The tropospheric flow data, which is input to the model, includes both 500 hPa height and 500 1000 hPa thickness fields which are compressed via an EOF-technique. The regression coefficients are calculated from a 27 year record of analysed flow and locally observed DTR and cloudiness. The regression model has been used to down-scale the large-scale flow produced in a CO2 sensitivity experiment with a coupled ocean-atmosphere climate model (ECHAM-1). The down-scaled ""high CO2"" DTR is generally smaller than found when down-scaling the corresponding climate model control experiment. The opposite statement applies to cloudiness. DTR-anomalies of the order 2 Kelvin (K) are obtained in the central/northern parts of Fenno-Scandia in the middle of the 21st century while anomalies much closer to zero are found over the Iceland/Southern Greenland region. Consistent with this picture the cloudiness anomalies in the high CO2 case are predicted highest near the central/northern parts of Fenno-Scandia. The results presented here indicate that periods observed to be anomalously warm on a large-scale - corresponding to high CO2 concentrations - are also observed to be more cloudy and it is argued that clouds may have a thermostatic effect. We have calculated DTR and cloud cover trends at the 10 stations used in the regression model in order to assess if they are consistent with the predicted estimates and as such reflect a forcing of the climate system. We find that none of the stations show DTR/cloud cover trends significantly different from zero in the period 1961-1987. We do, however, see a negative DTR trend and a positive cloud trend when we consider a slightly longer time series (1950-1992) at Reykjavik. All statements about trends are, however, very uncertain because the observed records in addition to any trends reflect a large natural variability on decadal time scales as well as possible observational inhomogeneities. © 1995."
"57203200427;57203053317;","The sulfate‐CCN‐cloud albedo effect",1995,"10.1034/j.1600-0889.47.issue3.1.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982665574&doi=10.1034%2fj.1600-0889.47.issue3.1.x&partnerID=40&md5=4a317cdc0db46b96e50080f782c38099","Aerosol particles, such as sulfate aerosols, can act as cloud condensation nuclei (CCN). The CCN spectrum and the water vapour supply in a cloud determine the cloud droplet number concentration (CDNC) and hence the shortwave optical properties of low‐level liquid clouds. The capability of anthropogenic aerosols to increase cloud reflectivity and thereby cool the Earth's surface is referred to as the indirect effect of anthropogenic aerosols. To obtain an estimate of this effect on climate, we empirically relate the CDNC, and thus the cloud optical properties, of two general circulation models (GCM) to the sulfate aerosol mass concentration derived from a chemical transport model. Based on a series of model experiments, the normalized globally averaged indirect forcing is about − 1 W/m2 and ranges from – 0.5 to − 1.5 W/m2 in both GCMs for different experiments. However, it is argued that the total uncertainty of the forcing is certainly larger than this range. The overall agreement between the two climate models is good, although the geographical distributions of the forcing are somewhat different. The highest forcings occur in and off the coasts of the polluted regions of the Northern Hemisphere. The regional distribution of the forcing and the land/sea contrast are very sensitive to the choice of the CDNC‐sulfate mass relationship. The general patterns of the forcing, and the appropriateness of the different CDNC‐sulfate mass relationships, are assessed. We also examine the simulated droplet effective radii and compare them with satellite retrievals. Copyright © 1995, Wiley Blackwell. All rights reserved"
"7403442230;7004974696;7003635928;","A ground based measurement of the anomalous cloud absorption effect",1995,"10.1029/95GL02084","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029506073&doi=10.1029%2f95GL02084&partnerID=40&md5=e011dde8379e2f6cc0824a90cbf3c1d7","Measurements of the solar shortwave flux using equipment based on solar cell sensors and pyranometers have yielded new information concerning the anomalous cloud absorption effect. A comparison of the solar fluxes for clear and overcast skies in January and February, 1995 suggests that the near‐infrared portion of the solar spectrum beyond 1.1 microns is absorbed preferentially by clouds. In addition, by comparing the observed and modelled column transmittances, it appears that the solar radiation beyond 1.1 microns is absorbed at higher transmittances than expected. On the average, the column absorption under heavy clouds was about 50 W/m², up to a maximum of about 75 W/m². An approximate estimate of the cloud radiative forcing (CRF) ratio was made for overcast days, and it was found to vary from 1.4 to 2.0, in general agreement with the CRF ratio reported by Cess et al. [1995]. It has been assumed previously in climate models that clouds scatter about 30% of the incident solar radiation while absorbing only about 4%. However, the maximum anomalous absorption of about 50 W/m² that we have measured is large in comparison to the radiative forcing of 3.3 W/m² that has been attributed to the presence of greenhouse gases since the pre‐industrial period, and may possibly imply that the climate predictions from general circulation models will have to be recomputed. Copyright 1995 by the American Geophysical Union."
"35977548400;7102018821;","Ice microphysics and climatic temperature feedback",1995,"10.1016/0169-8095(94)00014-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028813035&doi=10.1016%2f0169-8095%2894%2900014-5&partnerID=40&md5=4e1dd125d6e8a67fb0564ab85dde5d16","The potential effects of ice microphysics involving ice crystal size distribution and ice water path (IWP) on climatic temperature perturbations are investigated by using a one-dimensional radiative-turbulent climate model. We define a mean effective size, denoting the width of ice crystals weighted by the geometric cross section area, to represent ice crystal size distribution. Based on aircraft measurements, both the mean effective size and IWP are related to temperature and may be parameterized as functions of temperature. The radiative properties of cirrus clouds are further parameterized in terms of these two basic cloud physics parameters. Using CO2 doubling as the radiative forcing, feedbacks among temperature, the mean effective size and IWP, and the radiative properties of clouds are analyzed from the model results. We show that overall, a positive feedback associated with ice microphysics and the coupled radiative transfer is produced by temperature increase. © 1995."
"55722586400;55678879300;6602744181;","Simulation of climate change over europe using a nested regional‐climate model. I: Assessment of control climate, including sensitivity to location of lateral boundaries",1995,"10.1002/qj.49712152610","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028984747&doi=10.1002%2fqj.49712152610&partnerID=40&md5=0cfdce212e2088e7530cffe04116b53a","Present‐day climate simulations for Europe are presented, based on a 50 km regional‐climate model (RCM) driven by output from a global general‐circulation model (GCM) using a one‐way nesting approach. Both models are components of the Meteorological Office Unified Forecast/Climate Model and use the same subgrid‐scale physics. the relationship between the RCM circulation and that of the driving GCM was assessed in seasonal RCM integrations using domains of different sizes. In the larger domains, both the mean flow and the day‐to‐day variability in the RCM diverge from that of the GCM on the synoptic scale, rendering the RCM solution physically inconsistent with the GCM solution external to the RCM domain. At the grid‐point scale the RCM freely generates its own features, even in the smaller domains—only at points adjacent to the boundary buffer zone is there evidence of significant distortion by the lateral boundary forcing from the GCM. Using one of the smaller domains, a 10‐year RCM simulation was carried out, driven by a coupled atmosphere/mixed‐layer‐ocean version of the GCM. Over the region of interest the general circulation and daily synoptic variability is realistically simulated by the GCM and, therefore, also by the RCM (see above). Stronger vertical motions in the RCM lead to a general increase in dynamical precipitation relative to the GCM, and thus a drier and warmer troposphere and reduced convective cloud and precipitation. Layer‐cloud cover is also reduced in the RCM, due to a time‐step dependence in the treatment of the dissipation of ice cloud. Significant changes occur in the surface heat balance. the spatial patterns of surface air temperature and precipitation over Europe are well simulated by both the GCM and the RCM on scales resolved by the former. At finer scales the RCM contains a strong signal which is related to orographic height. Validation against a detailed observed climatology for Great Britain demonstrates that this signal contains considerable skill. Copyright © 1995 Royal Meteorological Society"
"56157800800;","Early Earth's climate: Cloud feedback from reduced land fraction and ozone concentrations",1995,"10.1029/95GL00818","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029471881&doi=10.1029%2f95GL00818&partnerID=40&md5=b627b3528ef2047cb2cc25166ec3bb6d","Two features of early Earth—reduced ozone (O3) concentration and land fraction are investigated with a general circulation model (GCM). These features are components of a paradox (Faint‐Young Sun paradox) which has intrigued researchers for more than two decades. In this study, land fraction and O3 concentrations are uniformly reduced by 100 percent. The reduction in O3 takes place in the troposphere and stratosphere with all other variables held constant including present‐day land fraction. Two sensitivity tests under global ocean conditions are reported: one case with implied oceanic poleward transports of heat, the other case with no implied oceanic poleward transports of heat. The results show that the removal of land under present‐day conditions increases cloud fractions and cool surface temperatures, unless heat is transported poleward by oceans. In a third sensitivity test with zero O3 concentrations, global mean air temperatures are increased by 2 K because of an increase in upper tropospheric and lower stratospheric clouds. The clouds enhance the greenhouse effect within the troposphere, increasing downward longwave radiation to the surface, melting sea ice and snow. Similar studies using radiative‐convective models which do not include interactive clouds do not show such surface warming. Copyright 1995 by the American Geophysical Union."
"35619149500;","The impact of clouds on the radiative heating of the earth surface-atmosphere system determined from satellite data",1995,"10.1016/0273-1177(95)00378-R","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028880145&doi=10.1016%2f0273-1177%2895%2900378-R&partnerID=40&md5=83e9b8bc6329670a08bdaf39a8ca5940","During the last 30 years observations from earth-orbiting and geostationary satellites have greatly improved the quality and detail of information about the global distribution of clouds and their effects on the energy balance of the Earth. Data from the Earth radiation experiments provide excellent data sets to study the diurnal, seasonal, and regional variations of the radiation balance of the climate system and how it is affected by the radiative forcing of clouds. These types of investigations are supplemented by use of the International Satellite Cloud Climatology Project data set which, with its unprecedented spatial and temporal resolution, describes the variability of the atmosphere and the embedded clouds. Cloud radiative forcing at the top of the atmosphere represents the overall effect of clouds on the Earth surface-atmosphere system. But, even if the cloud forcing at the top of the atmosphere is small, there might be a strong effect of clouds on the weather and climate processes which is felt through the changes in radiative interaction at the surface and in the atmosphere separately. Thus, after firstly looking at the energy balance at the top of the atmosphere, the above mentioned data sets are now more used to determine also the energy balance at the surface. For instance, the Global Energy and Water Cycle Experiment Surface Radiation Project is retrieving fluxes of shortwave surface radiation over the globe from the International Satellite Cloud Climatology Project data. The Surface Radiation Project will shortly extend the retrievals to the longwave. The uncertainty in deriving the cloudbase altitudes from the satellite data leads to the largest errors in determining the net longwave fluxes at the surface. Despite the problem of retrieving the cloud bottom heights from currently available global satellite data sets, first attempts are made to study the effects of clouds on the radiative heating of the atmosphere inselt. First results sustain that the effect of clouds in the shortwave spectral domain is primarily a cooling of the surface. In the longwave spectral domain the effect of clouds is primarily on the atmosphere, where the distribution of cloud atmospheric forcing strengthens the meridional temperature gradient. To improve the efforts to determine the atmospheric heating profiles and the net longwave radiation budget at the surface, a global measurement of cloud layering and vertical cloud thickness is urgently needed. A space borne millimeter wave radar will provide the information about the vertical structure of clouds and cloudbase altitude, and, with suitable complementary measurements, is a promising method to provide estimates of water and ice mass. © 1995."
"6603278773;7003613864;","Information about scattering properties and particle characteristics of a stratiform cloud at Helgoland by remote optical measurements",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029513367&partnerID=40&md5=a79d9f1709e0a573f2e71f6bebdf8099","Results of combined measurements of spectral optical thickness and sky brightness in the almucantar are presented for the case of a homogeneous low-level stratiform cloud at Helgoland island in the North Sea with a quite low optical thickness. It is demonstrated that a Coupled Inversion Radiation Transfer program (CIRATRA) which is usually employed for the determination of climate-relevant parameters of atmospheric aerosols can be used also for determining physical and optical properties of thin homogeneous clouds. Using the semi-empirical scattering theory of Polack and Cuzzi, 1980 for the scattering of nonspherical particles gives a very good agreement between observed and calculated sky brightness. -from Authors"
"7003509260;","Climate changes predicted by climate models for the increase of greenhouse gases",1995,"10.1016/0149-1970(95)00038-L","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346701370&doi=10.1016%2f0149-1970%2895%2900038-L&partnerID=40&md5=8f0cc2a3be766a51151ddda1cf3b9cef","Climate models have been used to predict climate changes caused by the increase of greenhouse gases. Models predict physical states of the upper part of the earth including the atmosphere, the ocean, the land surface and the cryosphere with the use of physical laws. When atmospheric concentration of C02 is doubled, globally averaged surface temperature is predicted to increase 1.5 to 4.5°C. Temperature increase is most dominant in winter of high latitudes due mainly to sea ice-albedo and snow-albedo feedbacks. Geographically, it is dominant over continents in high latitudes. Hydrological cycle is activated. Precipitation as well as evaporation increases, in globally averaged sense, by 3 to 15%. Precipitation is divided into two types, i.e., precipitation from cumuli-form clouds and that from strati-form clouds. The former (latter) type increases (decreases) in globally averaged sense. Therefore precipitating area decreases while precipitation amount increases. In summer, many models predict decrease in soil moisture in mid-latitudes. When atmospheric C02 concentration increases at the compound rate of 1% per year, globally averaged surface temperature increase is about 60% of the equilibrium value, i.e., 0.9∼2.7°C. Remaining 40% is left for potential increase in future. The increase in the southern hemisphere is less than that in the northern hemisphere. Delay in the temperature increase is noted especially over the Antarctic Ocean and north-eastern part of the North Atlantic due mainly to deep oceanic circulations in those area. © 1995."
"7202513968;","The panorama of Neotropical cloud forests",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029527504&partnerID=40&md5=77256bc5425850f505bdeffd05a5d837","Neotropical cloud forests extend from 23°N to 25°S. In the north (Mexico) they are isolated and surrounded by xeric vegetation; in the south (Chile and Argentina) they grade into temperate rain forests. Elevationally, typical (modal) cloud forest is generally found between 1000-3000 m. Lower montane cloud forests (1000-2000 m) are characterized by a high percentage of epiphytes, ferns, and tropical taxa such as Annonaceae, Melastomataceae, palms, and Cyclanthaceae. Upper montane forests differ in the presence of such distinctly temperate-climate taxa as Podocarpus, Alnus, Drimys, Weinmannia, and Magnoliaceae. The geographic distribution patterns of Neotropical cloud forest taxa have been strongly influenced by the Pliocene reconnection between North and South America, which has permitted extensive reciprocal migrations of Andean taxa (eg Drimys) north and cordilleran taxa (eg Juglans) south. Endemism in cloud forest taxa is low at the generic level but high at the species level, suggesting recent and rapid speciation. -from Author"
"7004607037;7004131981;6701773543;","The estimation of thermal atmospheric radiation under cloudy conditions",1995,"10.1002/joc.3370150111","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028888121&doi=10.1002%2fjoc.3370150111&partnerID=40&md5=3f8efbce667896f7daf94dd17f71aa4e","Among the surface radiation budget components that are needed to understand the climate of the Earth, the thermal atmospheric radiation component is the only one that is not measured routinely, so it must be estimated indirectly. The presence of clouds substantially hampers this task, supplementing the emission of water vapour and carbon dioxide in the lower atmosphere. The methods proposed to estimate thermal atmospheric radiation often rely on a cloudless sky model and a corrective term that takes into account the cloud contribution. Several models for estimating the thermal atmospheric radiation under cloudy conditions have been tested using measurements recorded in Granada (Spain) during a period of 2 years. The cloudless sky model provides estimation with an error of about 5 per cent, whereas the cloudy skies models, after some modifications, estimate thermal atmospheric radiation with an error of about 6 per cent. Our results show the convenience of a quadratic dependence on cloud amount for cloudy skies models. In addition to this, it seems convenient to use available information about the radiative properties of clouds to assign different cloud emittances for different types of clouds within each level, especially for middle level clouds. Copyright © 1995 John Wiley & Sons, Ltd"
"6701333444;7005626683;","Relating cirrus cloud properties to observed fluxes: a critical assessment",1995,"10.1175/1520-0469(1995)052<4285:RCCPTO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029434735&doi=10.1175%2f1520-0469%281995%29052%3c4285%3aRCCPTO%3e2.0.CO%3b2&partnerID=40&md5=94c6651008b553839baaf56131a452a7","The accuracy needed in cirrus cloud scattering and microphysical properties is quantified such that the radiative effect on climate can be determined. Our ability to compute and observe these properties to within needed accuracies is assessed, with the greatest attention given to those properties that most affect the fluxes. For a baseline case (defined in text), computing net shortwave fluxes at the surface to within ±5% requires accuracies in cloud ice water content that, when the optical depth is greater than 1.25, are beyond the accuracies of current measurements. Similarly, subsurface shortwave flux computations require accuracies in the asymmetry parameter that are beyond our current abilities when the optical depth is greater than four. Unless simplifications are discovered, the scattering properties needed to compute cirrus cloud fluxes cannot be obtained explicitly with existing scattering algorithms."
"6701413579;7004299063;","Diurnal asymmetry of climatic response to increased CO2 and aerosols: forcings and feedbacks",1995,"10.1029/95jd02166","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029476882&doi=10.1029%2f95jd02166&partnerID=40&md5=9d6ed49a27c601d8b2bbca0ee4a263c2","To examine the causes of the observed diurnally asymmetrical climate change over land, the roles of different physical mechanisms are evaluated using a radiative-convective model of the diurnal cycle. This model explicitly calculates a complete set of physical processes, including the water vapor distribution, clouds, transports in the turbulent boundary layer, and convection. Calculations were carried out for midlatitude summer and winter and for tropical spring conditions taking into account the most important climate forcings: CO2 increase, tropospheric aerosol pollution, and the combined case with simultaneous CO2 and aerosol effects. -from Authors"
"7006434399;","Simulations of Southern African climate by early generation general circulation models",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028846274&partnerID=40&md5=de2af5ed564ad0aa4a73d62d5da876b0","The validation focuses on the simulation of the pattern and magnitude of observed surface air temperatures, mean sea-level pressures and precipitation. Calculated errors in the simulation of southern African climate are generally characteristic of those reported elsewhere for this generation of mixed-layer slab-ocean equilibrium climate models. In each case, errors in the simulation of a particular variable are related to the representation in the models of physical processes important to the region's climate. Surface air temperature simulations are sensitive to the parameterization of cloud radiative feedbacks and cumulus convection. Accurate representation of the equator-to-pole surface pressure gradient is strongly dependent on the inclusion of a gravity wave drag term in the parameterization of surface stress. Convective precipitation is poorly simulated by the coarse-resolution models considered in this analysis. -Author"
"7409953339;7202208382;","Impact of interactive radiative transfer on the macroscopic behavior of cumulus ensembles. Part II: mechanisms for cloud-radiation interactions",1995,"10.1175/1520-0469(1995)052<0800:ioirto>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029526331&doi=10.1175%2f1520-0469%281995%29052%3c0800%3aioirto%3e2.0.co%3b2&partnerID=40&md5=891dd211e6239a5cd18d6c6162683f14","The two-dimensional UCLA cumulus ensemble model is used to examine the impact of cloud-radiation interactions on the macroscopic behavior of cumulus ensembles. Two sets of simulations are performed with noninteractive (NI) and fully interactive (FI) radiative transfer, and with prescribed large-scale advective effects. The diurnally varying solar radiation can drive a diurnal cycle of deep convection over the tropical oceans by stabilizing the large-scale environment during the daytime relative to the nighttime. The results presented in this study confirm the dominant role of the direct radiation-convection interaction mechanism for the diurnal cycle or oceanic precipitation. The impact of longwave-cloud interactions on the macroscopic behavior of cumulus ensembles is a slightly stronger modulation of cumulus activity by large-scale processes. Upper-tropospheric clouds are somewhat more active and last longer in the presence of interactive radiation. -from Authors"
"7004378017;","An approach to remote sensing and numerical modeling of orographic clouds and precipitation for climatic water resources assessment",1995,"10.1016/0169-8095(94)00027-B","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028976249&doi=10.1016%2f0169-8095%2894%2900027-B&partnerID=40&md5=a08ca80f34234099aff3db34226622dd","State-of-the-art numerical models combined with new remote sensing technologies offer powerful means for determining the water budgets of cloud systems and addressing regional water resources issues. With specific examples from current technologies and a three-dimensional numerical model, this paper discusses the potential for accurately measuring and modeling the formation and fallout of mountain precipitation, a critical factor in the global climate system because it affects water resources. This paper describes application of the model and remote sensors to meet the goals of programs such as the Global Energy and Water Cycle Experiment (GEWEX). To accurately predict precipitation, general circulation models that have 100-km grid spacing require parameterization of the effects of subgrid-scale processes within cloud systems. The contribution of scales of atmospheric motion 10-20 km in forming precipitation and determining its distribution on mountain ranges is demonstrated. © 1995."
"7004189939;7102244456;7202496599;8225183400;","Comparison of observed seasonal temperature maxima, minima and diurnal range in North America with simulations from three global climate models",1995,"10.1016/0169-8095(94)00082-O","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029473847&doi=10.1016%2f0169-8095%2894%2900082-O&partnerID=40&md5=443c5514bcb69143230a0c32bc32415d","Confidence in model projections of climate change requires reasonably realistic simulation of present-day climate (Wilson and Mitchell, 1987; Boer, 1992). Accordingly, we compare surface air temperatures simulated in the control runs of three general circulation models (Canadian Climate Centre, Oregon State University, United Kingdom Meteorological Office) with observations in three regions of the central United States. The models simulate a smaller diurnal surface air temperature range, averaging overall 3.2°C less than observed. Spring maxima are consistently lower in the models by an average of 4.1°C. Although inadequate representation of clouds may contribute to the smaller simulated temperature range, the underlying cause of the differences is unknown. Since increased minima and decreased diurnal ranges are the most widely observed features of surface air temperature over the Northern Hemisphere continents during the last four decades, the discrepancy is a matter of concern for the projection of future greenhouse-gas-induced climate changes and their impacts. © 1995."
"7410255460;7006432091;6701670597;6507809414;35584010200;","TOGA COARE satellite data summaries available on the World Wide Web",1995,"10.1175/1520-0477(1995)076<0329:TCSDSA<2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029527604&doi=10.1175%2f1520-0477%281995%29076%3c0329%3aTCSDSA%3c2.0.CO%3b2&partnerID=40&md5=22adedcb5957794a33781596401816d7","Satellite data summary images and analysis plots from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE), are now available on the Internet. These satellite data summaries consist of products derived from the Japanese Geosynchronous Meteorological Satellite IR data: a time-size series of the distribution of contiguous cold cloudiness areas, weekly percent high cloudiness (PHC) maps, and a five-month time-longitude diagram illustrating the zonal motion of large areas of cold cloudiness. -from Authors"
"7404334532;7405727977;6604021707;","Long-term changes of the diurnal temperature cycle: implications about mechanisms of global climate change",1995,"10.1016/0169-8095(94)00077-Q","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029528414&doi=10.1016%2f0169-8095%2894%2900077-Q&partnerID=40&md5=bbe0948ca827c552c619f07a3f1d20ac","We use a global climate model to investigate the impact of a wide range of radiative forcing and feedback mechanisms on the diurnal cycle of surface air temperature. This allows us not only to rule out many potential explanations for observed diurnal changes, but to infer fundamental information concerning the nature and location of the principal global climate forcings of this century. We conclude that the observed changes of the diurnal cycle result neither from natural climate variability nor a globally-distributed forcing, but rather they require the combination of a (negative) radiative forcing located primarily over continental regions together with the known globally-distributed forcing due to anthropogenic greenhouse gases. Tropospheric aerosols can account for part of the continentally-located forcing, but alone they do not damp the diurnal cycle as observed. Only an increase of continental cloud cover, possibly a consequence of anthropogenic aerosols, can damp the diurnal cycle by an amount comparable to observations. A corollary of these results is quantitative confirmation of the widely held suspicion that anthropogenic greenhouse gas warming has been substantially counterbalanced by a forced cooling. Under the assumption that the cloud change is sulfate driven, a further implication is that the net rate of global warming is likely to increase substantially in coming years. We note that, on the long run, the daily maximum temperature will increase by an amount not much less than the increase of the mean temperature. © 1995."
"7005310521;7405586876;7403335892;","Possible role of oceanic heat transport in Early Eocene climate",1995,"10.1029/94PA02928","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028975812&doi=10.1029%2f94PA02928&partnerID=40&md5=50095f1b45f09b09a68533502eb78de4","Increased oceanic heat transport has often been cited as a means of maintaining warm high‐latitude surface temperatures in many intervals of the geologic past, including the early Eocene. Although the excess amount of oceanic heat transport required by warm high latitude sea surface temperatures can be calculated empirically, determining how additional oceanic heat transport would take place has yet to be accomplished. That the mechanisms of enhanced poleward oceanic heat transport remain undefined in paleoclimate reconstructions is an important point that is often overlooked. Using early Eocene climate as an example, we consider various ways to produce enhanced poleward heat transport and latitudinal energy redistribution of the sign and magnitude required by interpreted early Eocene conditions. Our interpolation of early Eocene paleotemperature data indicate that an ∼30% increase in poleward heat transport would be required to maintain Eocene high‐latitude temperatures. This increased heat transport appears difficult to accomplish by any means of ocean circulation if we use present ocean circulation characteristics to evaluate early Eocene rates. Either oceanic processes were very different from those of the present to produce the early Eocene climate conditions or oceanic heat transport was not the primary cause of that climate. We believe that atmospheric processes, with contributions from other factors, such as clouds, were the most likely primary cause of early Eocene climate. Copyright 1995 by the American Geophysical Union."
"56304464500;","A GCM simulation of global climate interannual variability: 1950-1988",1995,"10.1175/1520-0442(1995)008<0709:AGSOGC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029502992&doi=10.1175%2f1520-0442%281995%29008%3c0709%3aAGSOGC%3e2.0.CO%3b2&partnerID=40&md5=06afe1056ec75645e9e26e5cd904fa35","Three long-term climate simulations have been performed with an atmospheric general circulation model using monthly global SSTs for the period 1950-1988. EOF analysis is used to study the ensemble-mean results for seasonal-mean fields as a means of evaluating the capability to simulate interannual variability. The analysis reveals a strong ENSO-related signal in the major fields of mean sea level pressure, rainfall, cloud cover, and zonal winds. The leading EOFs are compared, where possible, with observed ENSO-related patterns. The EOF for surface pressure closely resembles the Southern Oscillation pattern but, although significantly correlated with the Southern Oscillation index, cannot explain a large proportion of the observed variance. -from Author"
"7403233451;13806362800;","A global climate model (GENESIS) with a land-surface transfer scheme (LSX). Part I: present climate simulation",1995,"10.1175/1520-0442(1995)008<0732:AGCMWA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029535239&doi=10.1175%2f1520-0442%281995%29008%3c0732%3aAGCMWA%3e2.0.CO%3b2&partnerID=40&md5=b873e89d80f0ca6729e1d8c796abd694","The present-day climatology of a global climate model (GENESIS Version 1.02) is described. The model includes a land-surface transfer component (LSX) that accounts for the physical effects of vegetation. The atmospheric general circulation model is derived from the NCAR CCM1 and modified to include semi-Lagrangian transport of water vapor, subgrid plume convection, PBL mixing, a more complex cloud scheme, and a diurnal cycle. The surface models consist of LSX; multilayer models of soil, snow, and sea ice; sea ice dynamics; and a slab mixed layer ocean. The results are compared with those using a simplified bucket-soil model and crude parameterizations of surface albedo and roughness. Although quite similar results are obtained on global scales, significant regional differences including surface warming and drying occur in some regions of Amazonia and northern midlatitude continental interiors. -from Authors"
"55547129338;7401548835;","Climate change and the Arctic hydrologic cycle as calculated by a global coupled atmosphere-ocean model",1995,"10.3189/s0260305500015652","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029472401&doi=10.3189%2fs0260305500015652&partnerID=40&md5=e0b02f10f572b99e105cfde87ccf0635","A global coupled atmosphere-ocean model is used to examine the hydrologic cycle of the Arctic Ocean. A 74 year control simulation of the present climate is used to examine variability of the hydrologic cycle, including precipitation, sea ice, glacial ice and river discharge. A 74 year transient simulation in which atmospheric CO2 increases each year at a compound rate of 1% is then used to examine potential changes in the hydrologic cycle. Among these changes are a 4°C increase in mean annual surface air temperature in the Arctic Ocean, a decrease in ice cover which begins after 35 years, and increases in river discharge and cloud cover. -from Authors"
"35461763400;55925779800;7006926020;","Biogenic sulfur emissions and aerosols over the tropical South Atlantic: 3. Atmospheric dimethylsulfide, aerosols and cloud condensation nuclei",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029135576&partnerID=40&md5=f0d0e70f0aeb18d499348ccc67e8aeec","We measured dimethylsulfide in air (DMS""SUB a"" ) and the number concentration, size distribution, and chemical composition of atmospheric aerosols, including the concentration of cloud concentration nuclei (CCN), during February-March 1991 over the tropical South Atlantic along 19 degrees S (F/S Meteor, cruise 15/3). Aerosol number/size distributions were determined with a laser-optical particle counter, condensation nuclei (CN) concentrations with a TSI 3020, and cloud condensation nuclei (CCN) with a Hudson-type supersaturation chamber. Meteorological analysis shows that most of the air masses sampled had spent extended period over remote marine areas in the tropical and subtropical region. Results provide strong support for several aspects of the CLAW hypothesis, which proposes the existence of a feedback loop thinking DMS emission from marine plankton to sulfate aerosol and global climate. (from Authors)"
"7405586876;","There is more to climate than carbon dioxide",1995,"10.1029/95RG00346","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347025130&doi=10.1029%2f95RG00346&partnerID=40&md5=796cdb9e96d7a8ec6c3b527675eb17b5","Discussion of climate change on a range of time scales has tended to focus on carbon dioxide and a changing greenhouse effect. Because carbon dioxide couples climate to ocean, land, and biota, it has appealed to scientists with an interest in the whole Earth system. Carbon dioxide has left a geological record in fossils, isotopes, and sediments, so we can reasonably expect to reconstruct its history. While important questions of detail remain to be resolved, many published applications of carbon cycle modelling suggest that we understand the biogeochemical cycles of carbon well enough to estimate carbon dioxide concentrations in the past and the future. Furthermore, we have an excellent instrumental record of recent changes in atmospheric carbon dioxide. While these considerations make carbon dioxide attractive to paleoclimatologists, they do not necessarily make it a major component of climate change. I shall argue in this paper that clouds deserve much more attention than they have been getting. Copyright 1995 by the American Geophysical Union."
"7005882490;16185051500;7004546686;7006508110;","Measurements of some aerosol properties relevant to radiative forcing on the east coast of the United States",1995,"10.1175/1520-0450(1995)034<2306:MOSAPR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029504336&doi=10.1175%2f1520-0450%281995%29034%3c2306%3aMOSAPR%3e2.0.CO%3b2&partnerID=40&md5=b6604abc5614a0c7f550185489ab9361","Airborne measurements of aerosol light-scattering efficiencies are presented for a portion of the northeast Atlantic seaboard of the United States during July 1993. The measurements suggest a value for the sulfate light-scattering efficiency in the range 2.2-3.2 m2g-1, which is lower than the value used in recent modeling assesments of the climate impact of aerosols. In general, the sulfate light-scattering efficiency decreased with increasing latitude in a manner consistent with concurrent measurements of aerosol size distributions. Some limited measurements of cloud condensation nuclei and sea-salt particles are also presented. -Authors"
"6603337672;6603950281;","Recent frost date trends in the north‐eastern USA",1995,"10.1002/joc.3370150108","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028867960&doi=10.1002%2fjoc.3370150108&partnerID=40&md5=23f6d194000a72ee840ad44cb42c83fd","Uncertainty in projections of future climate, along with a need for policy makers and management to respond to change in climate, highlight the importance of the detection of trends in climatological time series. Selected indicators of regional climate status and change may well be related to indicators of ecological condition. Climate factors are known to stress ecosystems. With the identification and description of trends in biologically important climate descriptors this knowledge could be used to provide scenarios of biological changes. One aspect of climate which stresses forest ecosystems is described by the annual date of the last hard spring‐freeze (minimum temperature ⩽ −2·2°C). Averaged for New England, there was a significant linear trend indicating an earlier initiation of frost‐free conditions (negative slope) for the period 1961–1990. Significant time trends were detected locally at stations throughout much of the New England regions as well. Temporal discontinuities in trend, spatial relationships, and urban influence were considered. The presence of trends in time does not appear to be related to geographical location. The direction of trend (positive or negative) exhibits some geographical coherency, which may be related to climatological variables such as percentage of possible sunshine and cloud cover. Copyright © 1995 John Wiley & Sons, Ltd"
"7005968859;","Atmospheric aerosol research in the U.S.: 1991–1994",1995,"10.1029/95RG00597","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001321879&doi=10.1029%2f95RG00597&partnerID=40&md5=216c44a2df5e2c724ee786e668493020","A common theme underlying many aspects of recent atmospheric aerosol research is the role of particulate matter in climate and climate change. Aerosols influence climate directly, by scattering and absorbing solar radiation, and indirectly via their role as cloud condensation nuclei (CCN), by modifying optical properties and lifetimes of clouds. The atmospheric cycles of two radiatively‐important species—sulfate and soot—have been significantly perturbed by anthropogenic activities, and thus it is expected that anthropogenic aerosols will have significant effects on global mean radiative forcing. There is general agreement that, despite uncertainty in estimates, the averaged global direct effects of aerosols are not negligible and are probably comparable in magnitude but opposite in sign to anthropogenic greenhouse gas forcing. However, all estimates are subject to significant uncertainty, in part because of gaps in understanding of critical factors and relationships. To minimize these uncertainties, a combination of activities must be undertaken (NRC (National Research Council) [1993] and Penner et al. [1993a]): long‐term observations at fixed sites, to establish background conditions and trends; short‐term intensive observations, surface‐based and airborne; laboratory analyses and process studies; model development; and satellite observations to connect local observations to global measurements. There is also a need for new techniques for automated and real‐time measurements of aerosol chemical and physical properties. Components of IGAC (International Global Atmospheric Chemistry Program) and its U.S. component, GTCP (Global Tropospheric Chemistry Program) are focused on obtaining the data needed for quantifying the effects of aerosols on climate (NRC (National Research Council) [1993]), and indeed much of the research reported here reflects this priority. Copyright 1995 by the American Geophysical Union."
"7101867299;","Radiation and polar lows",1995,"10.1002/qj.49712152105","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028973714&doi=10.1002%2fqj.49712152105&partnerID=40&md5=721852b0cf531319dfcabb3e8dc85577","It is found that, in axisymmetric simulations of a convective polar low, long‐wave radiative cooling increases both growth rate and maximum intensity. This result is due to cooling of the system's environment relative to its warm core. The magnitude of the increase in growth rate is approximately 30%, but is sensitive to the parametrization of cloud microphysics and radiative properties. A steady‐state Carnot cycle was not obtained. Copyright © 1995 Royal Meteorological Society"
"56735614000;57207008570;35501654900;55424861100;56634405500;6701846836;","Long-term changes in the acid and salt concentrations of the Greenland Ice Core Project ice core from electrical stratigraphy",1995,"10.1029/95jd01174","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029540298&doi=10.1029%2f95jd01174&partnerID=40&md5=6ac59c87de97e197ba6b7f36506d22d9","Continuous electrical records covering a climatic cycle are presented. Electrical conductivity measurement (ECM) measures the acid content of the ice, and the dielectric profile (DEP) responses to acid, ammonium, and chloride. All features seen can be explained by chemical changes in the ice, and there is no evidence so far for any major change with ice depth or age. Both records are dominated by the acidity of the ice which varies strongly from acidic in warm periods to alkaline in cold periods, controlled by neutralization by alkaline dust (calcareous and other mineral dust). When Ca is low, the acidity (mainly nitric acid) has a fairly constant background level throughout the cycle, with slightly lower values in ice believed to be from the last interglacial. Ca has to rise only slightly to neutralize the available acidity, so that acidity is a highly nonlinear reflection of climate changes. If neutralization occurred in the aerosol (rather than in the ice), then the number of cloud condensation nuclei over parts of the northern hemisphere could have been reduced, leading to reduced cloud albedo. -from Authors"
"57197226964;7103293232;","Validation of downwelling longwave computations with surface measurements during FIFE 89",1995,"10.1029/95jd00385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029500844&doi=10.1029%2f95jd00385&partnerID=40&md5=0ea51b08d50842fe0baace807f7b8c3d","The amount of longwave radiation reaching the surface is a necessary parameter for climate modeling. As no extensive array of surface-based stations exists for monitoring the downwelling longwave surface flux (F ↓ (0)), satellite, computations of F ↓ (0) need to be validated with surface measurements. In this study the validation of computations of F ↓ (0) is carried out for both clear and cloudy conditions using data from the 1989 phase of the First ISLSCP Field Experiment (FIFE 89). FIFE 89 data is particularly useful for this study, as it contains lidar measuements of cloud base height and cloud fraction, thereby eliminating the need to estimate these parameters from other available data. -Authors"
"7202899330;","Review of atmospheric radiation: 1991–1994",1995,"10.1029/95RG00802","https://www.scopus.com/inward/record.uri?eid=2-s2.0-5244267430&doi=10.1029%2f95RG00802&partnerID=40&md5=2b3be39132bf14416ab561f74c49b1f6","It is appropriate to think of the discipline of atmospheric radiation as one of the building block subjects of the atmospheric sciences linking the fields of chemistry, aerosol and cloud physics, thermodynamics to global climate and climate change. A convenient way to think of the research of this discipline is to consider it divided into two broad but not necessarily distinct categories—one that seeks to understand how the interactions between radiation and the atmosphere determine the distribution of radiant energy on all scales and a second that attempts to exploit such an understanding, mostly as they apply on the smaller scale, to form the basis for most of the remote sensing methods currently used to observe the atmosphere. The first line of enquiry provides the fundamental understanding of the radiative forcing of climate, for example, and significant advances in our understanding of this forcing have emerged over the last few years. Perhaps even more activity has been invested in the second area of research especially with the emerging era of the Earth Observing System (EOS) [e.g., King et al., 1992]. Remote sensing has also become a tool in climate research over the last few years with the application of satellite data in studies of fundamental climate processes. Copyright 1995 by the American Geophysical Union."
"7006095466;","Mesoscale convection from a large-scale perspective",1995,"10.1016/0169-8095(94)00012-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028976988&doi=10.1016%2f0169-8095%2894%2900012-3&partnerID=40&md5=32c47764dfa4328216ed88fbc532594f","This essay concerns precipitating convective cloud systems and convectively-driven mesoscale circulations (""mesoscale convection"") and their role in the large-scale structure of the atmosphere. Mesoscale convection is an important and ubiquitous process on scales of motion spanning a few kilometers to many hundreds of kilometers. It plays a role in the input of energy to the climate system through the radiative effect of upper-tropospheric cloud and water vapor, and enhanced surface fluxes. This is in addition to its important effect on energy, heat and momentum transport within the atmosphere. However, mesoscale convection is neither parameterized nor adequately resolved in atmospheric general circulation models. Its representation in mean-flow terms raises issues that are quite distinct from classical approaches to sub-grid scale convection parameterization. Cloud-resolving modeling and theoretical concepts pertinent to the transport properties and mean-flow effects of organized convection are summarized, as are the main convective parameterization techniques used in global models. Two principal themes that are relevant to the representation of organized mesoscale systems are discussed. First, mesoscale transports and their sub-grid scale approximation with emphasis on dynamical approaches. Second, long time-scale modeling of mesoscale cloud systems that involves the collective effect of convection, boundary and surface layers, radiation, microphysics acting under the influence of large-scale forcing. Finally, major research programs that address the role of precipitating convection and mesoscale processes in global models are summarized. © 1995."
"56240220200;7006865669;","Changes in minimum and maximum temperatures at the Pic du Midi in relation with humidity and cloudiness, 1882-1984",1995,"10.1016/0169-8095(94)00075-O","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029528404&doi=10.1016%2f0169-8095%2894%2900075-O&partnerID=40&md5=d2351e5ef94e4d5d105e8c39ad497de3","In an attempt to contribute to the investigation on a global climate change, a historical series of minimum and maximum temperature data at the Pic du Midi, a mountain observatory at 2862 m a.s.l. in the French Pyrenees, is updated after correction of a systematic deviation due to a relocation of the station in 1971. These data, which now cover the 1882-1984 period, are examined in parallel with humidity and cloud cover data for the same period. From the beginning to the end of this period, observations show that the mean night-time temperature has increased by 2.39°C 100 yr while the mean daytime temperature has decreased by 0.50°C 100 yr. In consequence, the mean annual diurnal temperature range has dropped by 36% 100 yr. The maximum seasonal decrease is 46% 100 yr in spring. Season-to-season and year-to-year inter-relationships between minimum temperature, maximum temperature, relative humidity and cloud cover suggest that the decrease in maximum temperature is related to a concomitant increase of 15% 100 yr in both relative humidity and cloud cover. © 1995."
"7409953339;7202208382;","Inpact of interactive radiative transfer on the macroscopic behavior of cumulus ensembles. Part I: radiation parameterization and sensitivity tests",1995,"10.1175/1520-0469(1995)052<0785:ioirto>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029471847&doi=10.1175%2f1520-0469%281995%29052%3c0785%3aioirto%3e2.0.co%3b2&partnerID=40&md5=f1d4522102de0ec5733f1d2c60b2d8e6","Implementation of a broadband radiation parameterization in the UCLA cumulus ensemble model (CEM) is discussed in this study, with emphasis on the specific problems associated with adequate calculation of radiative transfer processes in the CEM. The lowest CEM layer is divided into a thick layer and a very thin layer near the surface for the longwave radiation calculation. Diagnostic tests have been performed to compare the accuracy of this parameterization with results from a more complicated radiative transfer model. Simulations with fully interactive radiation are performed to compare two methods for invoking the radiation module. Additional sensitivity tests are also performed to justify the omission of the radiative effects of rapidly falling precipitating particles. Other sensitivity tests are related to the adequacy of the domain size and horizontal resolution for studying the cloud-radiation interaction problems discussed in Part II. -from Authors"
"7202838373;7005520001;7102294773;7006270084;7003353142;7003666669;7102780811;7202048112;7004340452;7005004102;7003777379;7101832377;","The current state and future direction of Eulerian models in simulating the tropospheric chemistry and transport of trace species: a review",1995,"10.1016/1352-2310(94)00235-D","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028977045&doi=10.1016%2f1352-2310%2894%2900235-D&partnerID=40&md5=9752149988c91b446ac50c84c9169ac5","Limitations on comprehensive tropospheric chemistry/transport models are discussed within the context of a set of issues currently facing the environmental scientific and policy-making communities. A number of central improvements are discussed in a prioritized manner, with consideration of the key progress necessary to include feedback processes between meteorology and chemistry, aerosol formation, in cloud development with subsequent effects on wet removal, dry deposition and surface exchange processes, and impacts of chemical perturbations on radiation, climate, and weather. These improvements would result in a ""third-generation model"". The computational framework for this code is outlined, and estimates of required computer resources presented. © 1995."
"35240796300;7003640407;56033135100;","Sedimentological evaluation of general circulation model simulations for the ""greenhouse"" Earth: Cretaceous and Jurassic case studies",1995,"10.1016/0037-0738(95)00106-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029510326&doi=10.1016%2f0037-0738%2895%2900106-9&partnerID=40&md5=fb8ba1bb56f37fdf867d3bcf19c37fb2","Conceptual climate models, based on the workings of the present-day climate system, provided a first-order approach to ancient climate systems. They are potentially very subjective in character. Their main drawback was that they involved the relocation of continents beneath a stable atmospheric circulation modelled upon that of the present. General circulation models (GCMs) use the laws of physics and an understanding of past geography to simulate climatic responses. They are objective in character. However, they require super computers to handle vast numbers of calculations. Nonetheless it is now possible to compare results from different GCMs for a range of times and over a wide range of parameterisations. GCMs are currently producing simulated climate predictions which compare favourably with the distributions of climatically sensitive facies (e.g. coals, evaporites and palaeosols). They have been used effectively in the prediction of oceanic upwelling sites and the distribution of petroleum source-rocks and phosphorites. Parameterisation is the main weakness in GCMs (e.g. sea-surface temperature, orography, cloud behaviour). Sensitivity experiments can be run on GCMs which simulate the effects of Milankovitch forcing and thus provide insights into possible patterns of climate change both globally and locally (i.e. provide predictions that can be evaluated against the rock record). Future use of GCMs could be in the forward modelling of sequence stratigraphic evolution and in the prediction of the diagenetic characteristics of reservoir units in frontier exploration areas. The sedimentary record provides the only way that GCMs may themselves be evaluated and this is important because these same GCMs are being used currently to predict possible changes in future climate. © 1995."
"7103353990;7202198678;7103059813;12805239400;7005126327;","Stratospheric aerosol effective radius, surface area and volume estimated from infrared measurements",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029141328&partnerID=40&md5=6f09acdb55f56e4528cc5a0d7f01e865","A technique is presented for estimating the effective radius, surface area density and volume density of stratospheric aerosols from infrared emission measurements. These parameters are required to assess the perturbation of the climate and chemical balance of the stratosphere following the largest volcanic eruption so far this century: that of Mount Pinatubo in the Phillipines. The method uses a relationship between surface area density and the volume density derived from balloon-borne measurements of the Mount Pinatubo aerosol cloud. It is shown that the aerosol emission value is well approximated by a linear function of effective radius and aerosol volume density. The technique relies on knowing the refractive index of the aerosol cloud, which is assumed to be composed of liquid spheres of sulphuric acid and water. It is shown that the uncertainities in the current knowledge of the refractive index of sulphuric acid solutions limit the accuracy of the inversion technique. (Authors)"
"13806362800;7403233451;","Use of a land-surface-transfer scheme (LSX) in a global climate model: the response to doubling stomatal resistance",1995,"10.1016/0921-8181(94)00023-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029533364&doi=10.1016%2f0921-8181%2894%2900023-7&partnerID=40&md5=1ec0c8b3ca66de0fa1ba4c242890c527","One response of vegetation to future increases in atmospheric CO2 may be a widespread increase in stomatal resistance. Such a response would increase plant water usage efficiency while still allowing CO2 assimilation at current rates. The associated reduction in transpiration rates has the potential of causing significant modifications in climate on regional and global scales. This paper describes the effects of a uniform doubling of the stomatal resistance parameterization in a global climate model (GENESIS). The model includes a land-surface transfer scheme (LSX) that accounts for the physical effects of vegetation, including stomatal resistance and transpiration, which is described in detail in an appendix. The atmospheric general circulation model is a heavily modified version of the NCAR Community Climate Model version 1 with new treatments of clouds, penetrative convection, planetary boundary layer mixing, solar radiation, the diurnal cycle, and semi-Lagrangian transport of water vapor. The other surface models include multi-layer models of soil, snow and sea ice, and a 50-m slab ocean mixed layer. The effects of doubling the stomatal resistance parameterization are largest in heavily forested regions: tropical South America, and parts of the Northern Hemispheric boreal forests in Canada, Russia and Siberia in summer. The primary surface changes are a decrease in evapotranspiration, an increase in upward sensible heat flux, and a surface-air warming. Secondary effects include shifts in the ITCZ which cause large increases in precipitation, soil moisture and runoff in western tropical South America, and decreases in these quantities in northern subtropical Africa. Noticeable changes in relative humidity, cloudiness and meridional circulation occur throughout the troposphere. The global effects on atmospheric temperature and specific humidity are small fractions of those found in other doubled CO2 experiments. However, unlike doubled CO2 the signs of those changes combine to give relatively large reductions in relative humidity and cloudiness. It is suggested that the stomatal-resistance effect and other plant responses to large-scale environmental perturbations should be included in models of future climate. © 1995."
"57203048291;55424975000;","Modelling the effects of atmospheric C02 on vegetation-atmosphere interactions",1995,"10.1016/0168-1923(94)05079-L","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028790591&doi=10.1016%2f0168-1923%2894%2905079-L&partnerID=40&md5=2f8210cc2027fac190288dd1c5edac91","The effect of doubling atmospheric CO2 concentration (Ca) on climate and vegetation is investigated using a combined climate-vegetation model. The vegetation model predicts the response of leaf area index, canopy transpiration (ET) and whole-plant carbon balance to changes in climate, soil moisture, and atmospheric CO2 forcing. This model has been embedded in the UK Meteorological Office Single Column Model (SCM), which provides the climate feedback to the vegetation. The vegetation model uses an optimisation approach to predict stomatal resistance, a biochemical model to predict photosynthesis and a simple carbon balance model to predict leaf area. Respiration is calculated as a function of leaf area and vegetation height. Clouds are assumed to be radiatively passive in the SCM to avoid unrealistic feedbacks. Simulations were performed with the fully interactive vegetation-climate model for an Amazon location with the present-day value of Ca (1 × CO2), and twice this value (2 × CO2). In addition, two other types of simulation were performed at both CO2 concentrations: one in which the vegetation component was forced only with 1 × CO2, and one using a fixed surface resistance. The latter case is equivalent to simulations using most current general circulation models. In all the simulations, increased atmospheric CO2 caused an increase in surface temperature owing to increased radiative forcing. With a fixed resistance, mean ET was increased by 5.6% and sensible heat flux was reduced by 3.8%. The fully interactive model had significant effects on the response of both climate and productivity to Ca. Increased Ca caused stomatal closure, which resulted in a reduction in mean ET of 25%. The effect of Ca on ET was amplified by the positive feedback resulting from the effect of increased air humidity deficit on stomatal resistance. Gross primary productivity (GPP) was predicted to increase by 19.4% in the fully interactive model. With a fixed resistance, GPP increased by 34.3%. This difference in the predicted increase in GPP is due to the effect of stomata on the humidity of the planetary boundary layer. It is concluded that vegetation and climate responses to atmospheric CO2 concentration cannot be considered in isolation: the effects of the feedbacks could be at least as important as any direct effects. © 1995."
"7005703578;56072144700;55768583400;55469052600;7004212815;7003984281;","Construction of a 1961–1990 European climatology for climate change modelling and impact applications",1995,"10.1002/joc.3370151204","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028996046&doi=10.1002%2fjoc.3370151204&partnerID=40&md5=cb32811462bee75e5962c33e117b5210","A 1961–1990 mean monthly climatology for a ‘greater European’ region extending from 32°W to 66°E and from 25° to 81°N has been constructed at a resolution of 0.5°latitude by 0.5° longitude for a suite of nine surface climate variables: minimum, maximum, and mean air temperature; precipitation totals; sunshine hours; vapour pressure; wind speed; and (ground) frost day and rain day ( > 0.1 mm) frequencies. This climatology has been constructed from observed station data distributed across the region. Station frequencies range from 936 (wind speed) to 3078 (precipitation). Over 95 per cent of these data are based on observations between 1961 and 1990 and over 90 per cent were supplied by individual national meteorological agencies (NMAs) on specific request. For four variables, some standardization of the data had to be performed because different countries supplied data under different definitions. Thus cloud cover had to be converted to sunshine hours, relative humidity to vapour pressure, air frost days to ground frost days and rain days > 1 mm to rain days > 0.1 mm. The interpolation of the station data to the grid used elevation as one of the predictor variables and thus enabled three climate surfaces to be produced for each variable, reflecting the minimum, mean, and maximum elevation within each 0.5° by 0.5° cell. Subsets of stations were used for the interpolation of each variable, the selection being based on optimizing the spatial distribution, source priority and length of record. The accuracy of the various interpolations was assessed using validation sets of independent station data (i.e. those not used in the interpolation). Estimated mean absolute errors (MAE) ranged from under 4 per cent for vapour pressure to about 10 per cent for precipitation and up to 20 per cent for wind speed. The accuracy of the interpolated surfaces for minimum and maximum temperature was between 0.5°C and 0.8°C. We believe these results constitute the first climatology that has been constructed for this extensive European region at such a fine spatial resolution (0.5° by 0.5°) from relatively dense station networks, for three different elevation surfaces and for a wide range of surface climate variables, all expressed with respect to a standard 30‐year period. The climatology is already being used by researchers for applications in the areas of ecosystem modelling, climate change impact assessment and climate model validation, and is available from the authors. Copyright © 1995 John Wiley & Sons, Ltd"
"1;","Sunny vindication?",1995,"10.1029/EO076i018p00186-04","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980294704&doi=10.1029%2fEO076i018p00186-04&partnerID=40&md5=5da08cb3134bf006e7522d20c44ed7a8","Scientists have generally agreed that Earth's temperature has risen slightly during the past 100 years, by about 0.6°, in fact. But they have not been able to agree why. For one thing, the Sun has been a spoiler in the debate. While many scientists believe that greenhouse gases or even purely natural climate variations are to blame, others have insisted that the Sun may be a player in climate changes on Earth. The Sun maybe getting brighter or variations in the solar cycle may be driving temperature changes, they suggest. Because the Sun is difficult to remove from the equation, the issue has remained unsettled. Now in the April 7 issue of Science, David Thomson of AT&T Bell Laboratories in Murray Hill, N.J., may have brushed away some of the clouds. Using sophisticated techniques to study the statistical structure of time series, Thomson analyzed more than 300 years of temperature records. He found little evidence that the Sun is altering Earth's temperatures. In fact, he determined that the amplitude of the seasonal cycle is decreasing, which clashes with what would be expected if the Sun were getting brighter. He claims his finding “implies that solar variability cannot be the sole cause of the increasing temperature over the last century.” Though the Sun may play some role in climate change, Thomson writes in Science that the implications of his analysis are that “the effects of increasing greenhouse gases may be worse than previously thought.” Moreover, he writes, the finding calls for a reexamination of various climate parameters from orbital effects to seasonal temperature differences to annual temperature cycles. ©1995. American Geophysical Union. All Rights Reserved."
"7103246957;7401813827;","The FIFE surface diurnal cycle climate",1995,"10.1029/94jd03121","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029476591&doi=10.1029%2f94jd03121&partnerID=40&md5=1cbc73b0c6bc4cc5014a5f52028c57e4","Analyzes the diurnal cycle of the 2-m thermodynamic data averaged over the First International Land Surface Climatology Project (ISLSCP) Field Experiment site near Manhattan, Kansas, during 1987, using supporting soil moisture data, surface flux data, rainfall, and cloud formation. Further stratifications indicate the control of soil moisture on the surface evapotranspiration, vegetative conductance, and mean diurnal cycle for the boundary layer. We extract composite data sets for the daytime diurnal cycle over grassland in midsummer as a function of soil moisture and show that these are consistent with a mixed layer model for a rapidly entraining boundary layer. -from Authors"
"7404812403;7201483914;35974709800;54946955400;","Turbulent heat flux variation over the Monsoon-Trough region during MONTBLEX-90",1995,"10.1016/1352-2310(94)00363-P","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028991279&doi=10.1016%2f1352-2310%2894%2900363-P&partnerID=40&md5=1f8c319e9c4589b81987dba05923d1d2","Tower data collected during the Monsoon-Trough Boundary Layer Experiment (MONTBLEX-90) have been analysed to understand the observed structure of the surface layer over an arid region (Jodhpur) and a moist region (Kharagpur) during active and weak phases of the 1990 southwest monsoon. Turbulent heat and momentum fluxes are estimated by the eddy correlation method using sonic data. The turbulent momentum flux at both Jodhpur and Kharagpur was larger when the winds were stronger, reaching a maximum of the order of 0.5 N m-2 on 5 and 6 August when a low pressure system was located over the region. The heat flux at Jodhpur is high during weak monsoon days, the maximum being 450 W m-2, whereas during active days the flux never exceeds 200 W m-2. At Kharagpur, the flux does not vary significantly between active and weak monsoon days, the maximum in either phase being 160 W m-2. At Jodhpur, there is significant contrast in the near-surface air temperature, being higher during weak monsoon days as compared to active days. Cloud cover did not vary significantly in both the regions. The turbulent heat flux variation at both the sites appears to be correlated mainly with soil mixture, and less sensitive to cloud cover. © 1995."
"7006041041;6603234772;7005670010;","Daily and monthly maximum and minimum temperature datasets archived at NCAR and some applications",1995,"10.1016/0169-8095(94)00063-J","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029506804&doi=10.1016%2f0169-8095%2894%2900063-J&partnerID=40&md5=5995f9ccfdb2b82324672f8b7caef1d6","The temporal and spatial coverage of datasets archived at the National Center for Atmospheric Research which contain daily and monthly station observations are briefly described. These datasets form one of the foundations for climate research. Most commonly they contain daily minimum and maximum temperatures (Tmin and Tmax, respectively) and precipitation. Other variables are reported less often: these include sea level pressure, wind speed and direction, relative humidity, cloud type, etc. A proposed project to establish a global dataset containing daily Tmin, Tmax and precipitation observations from stations extending back to 1900 is outlined: Finally, some examples of research results derived using these observations are described. © 1995."
"6603250119;57202413846;","Radiative fluxes and their impact on the energy balance of the Greenland ice sheet",1995,"10.1017/S0022143000034833","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029478706&doi=10.1017%2fS0022143000034833&partnerID=40&md5=e0aeb9aa32a779faaa6f8975ecd9c034","A meteorological experiment was carried out during the summer months of 1990 and 1991 near the mean equilibrium-line altitude (ELA) on the western slope of the Greenland ice sheet. As a part of the project, the energy fluxes at the surface, including all components of the radiation balance, atmospheric profiles with a tower and radiosondes, and the cloud conditions were investigated in detail. Results from the radiative fluxes are compared with observations made at other locations in order to derive general characteristics of the radiation conditions on the Greenland ice sheet and their relation to the climate of the ice sheet. -from Authors"
"55738957800;7005453346;","Sensitivity of climate simulations to the parameterization of cumulus convection in the canadian climate centre general circulation model",1995,"10.1080/07055900.1995.9649539","https://www.scopus.com/inward/record.uri?eid=2-s2.0-39549095502&doi=10.1080%2f07055900.1995.9649539&partnerID=40&md5=cc694de1ee63b0655d709824f8aef4d5","A simplified cumulus parameterization scheme, suitable for use in GCMs, is presented. This parameterization is based on a plume ensemble concept similar to that originally proposed by Arakawa and Schubert (1974). However, it employs three assumptions which significantly simplify the formulation and implementation of the scheme. It is assumed that an ensemble of convective-scale updrafts with associated saturated downdrafts may exist when the atmosphere is locally conditionally unstable in the lower troposphere. However, the updraft ensemble is comprised only of those plumes which are sufficiently buoyant to penetrate through this unstable layer. It is assumed that all such plumes have the same upward mass flux at the base of the convective layer. The third assumption is that moist convection, which occurs only when there is convective available potential energy (CAPE) for reversible ascent of an undiluted parcel from the sub-cloud layer, acts to remove CAPE at an exponential rate with a specified adjustment time scale. The performance of the scheme and its sensitivity to choices of disposable parameters is illustrated by presenting results from a series of idealized single-column model tests. These tests demonstrate that the scheme permits establishment of a quasi-equilibrium between large-scale forcing and convective response. However, it is also shown that the strength of convective downdrafts is an important factor in determining the nature of the equilibrium state. Relatively strong down-drafts give rise to an unsteady irregularly fluctuating state characterized by alternate periods of deep and shallow convection. The effect of using the scheme for GCM climate simulations is illustrated by presenting selected results of a multi-year simulation carried out with the Canadian Climate Centre GCM using the new parameterization (the CONV simulation). Comparison of these results with those for a climate simulation made with the standard model (the CONTROL simulation, as documented by McFarlane et al., 1992) reveals the importance of other parameterized processes in determining the ultimate effect of introducing the new convective scheme. The radiative response to changes in the cloudiness regime is particularly important in this regard. © Taylor & Francis Group, LLC."
"35611825600;7003723474;7201392713;57147463800;7103216463;","Observing tropospheric water vapor by radio occultation using the Global Positioning System",1995,"10.1029/95GL02127","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029476208&doi=10.1029%2f95GL02127&partnerID=40&md5=cf5801b092dd957daf003f3f0d6d061e","Given the importance of water vapor to weather, climate and hydrology, global humidity observations from satellites are critical. At low latitudes, radio occultation observations of Earth's atmosphere using the Global Positioning System (GPS) satellites allow water vapor profiles to be retrieved with accuracies of 10 to 20% below 6 to 7 km altitude and ∼5% or better within the boundary layer. GPS observations provide a unique combination of accuracy, vertical resolution (≤ 1 km) and insensitivity to cloud and aerosol particles that is well suited to observations of the lower troposphere. These characteristics combined with the inherent stability of radio occultation observations make it an excellent candidate for the measurement of long term trends. Copyright 1995 by the American Geophysical Union."
"35508431200;7003828850;6603272945;7103239241;","Some observations on climate variability as seen in daily temperature structure",1995,"10.1016/0169-8095(94)00073-M","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029476423&doi=10.1016%2f0169-8095%2894%2900073-M&partnerID=40&md5=9b8693d1afed77d0b654c52019ea98d7","Distinctive annual cycles of daily maximum and minimum temperature and temperature range are observed across the United States when averaging daily data for multiple decades. In some cases, abrupt changes in the range between daily maximum and minimum temperatures are observed within annual cycles. Such discontinuities, or steps, of 5°C may occur within a week, despite the fact that the daily data are averaged over several decades. Discontinuities are most pronounced in the fall and spring, and display differing characteristics of timing, rapidity, magnitude and direction of change across the nation. In northern and central portions of the eastern U.S., a winter minimum and summer maximum in temperature range is observed, while in the southern U.S. the opposite is found. Abrupt discontinuities are observed in early November in the Northeast and in late spring and early summer in the Southeast and Southwest. Differences in mean daily temperature cycles between various portions of this century are a function of variations in maximum and minimum temperatures. The central U.S. had higher maximum and minimum temperatures during the 1930's than at other times this century, with little affect on daily temperature range. In the Northeast, the temperature range was lower in the 1930's, as a result of decreased maximum and increased minimum temperatures. The dynamics responsible for changes within the annual cycle or between different periods have not yet been unequivocally identified. The location of the polar front jet stream and its associations with solar radiation, clouds, snow cover and other atmospheric and surface variables are certainly involved. We believe that the identification of the climate system dynamics responsible for the structure of the annual cycle of daily temperature is a necessary first step in the study of potential human-induced climate change. © 1995."
"7102212075;7005034568;56130019800;","Estimating the probability of rain in an SSM/I FOV using logistic regression",1995,"10.1175/1520-0450(1995)034<2476:ETPORI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029529834&doi=10.1175%2f1520-0450%281995%29034%3c2476%3aETPORI%3e2.0.CO%3b2&partnerID=40&md5=fb526e2c574b40f1d97999d50f52890b","The SSM/I has been used successfully to estimate precipitation and to determine the fields of view (FOV) that contain precipitation clouds. The use of multivariate logistic regresion with the SSM/I brightness temperatures to estimate the probability that it is raining in an FOV is examined. The logistic regression technique is applied to a matched set of SSM/I and radar data for a limited area from June to August 1989. For this limited dataset the results are quite good. In one example, if the predicted probability is less than 0.1, the radar data shows only two of 340 FOVs have precipitation. If the predicted probability is greater than 0.9, the radar data shows precipitation in 748 of 774 FOVs. These probabilities can be used for both instantaneous and climate timescale retrievals. -from Authors"
"57215451474;","Reconsideration of the cause of dry air in the southern middle latitude stratosphere",1995,"10.1029/95GL01847","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029500653&doi=10.1029%2f95GL01847&partnerID=40&md5=a86651ad400b357687df4a50e2a5d5e2","A previous comparison of data from the Halogen Occultation Experiment (HALOE) and of output from the NCAR Community Climate Model (CCM2) in austral spring overstated the effect of dehydration in the southern polar vortex on lower stratospheric water vapor in part due to shortcomings in the HALOE retrieval algorithm and in part to remnants of the initially dry stratosphere in the CCM2 run. A new HALOE retrieval and a longer CCM2 run both show more water vapor than previously, but HALOE still shows less in the southern hemisphere than in the northern in September‐October 1992. A “dried‐air” tracer in the CCM2 suggests that polar dehydration influences middle latitudes only below about 100 hPa, and seasonal variations of HALOE H2O imply no influence north of 50°S. Copyright 1995 by the American Geophysical Union."
"55745955800;","Assessment of the SAGE sampling strategy in the derivation of tropospheric water vapor Distribution in a general circulation model",1995,"10.1029/95GL01336","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028881403&doi=10.1029%2f95GL01336&partnerID=40&md5=8fb380fd22ae8e1f0574d4d8ce2d2fd4","The Stratospheric Aerosol and Gas Experiment (SAGE) II has provided unprecedented information of water vapor distribution in the upper troposphere. For the purpose of comparison with output from climate models, the present study assesses the impact of the SAGE II sampling strategy on the tropospheric water vapor climatology in a general circulation model. Since water vapor is sampled only in “non‐cloudy” regions in the SAGE strategy, the sampled water vapor concentration is smaller than the real climatology. This difference is associated with two factors. One is the water‐vapor sampling frequency, the other is the humidity variability inside and outside the clouds. It is shown that maximum difference is at around 300 to 500 mb where it reaches up to 40% in the zonal mean humidity. Copyright 1995 by the American Geophysical Union."
"57204660182;7409777793;7409936843;7409521185;","The cooling of Sichuan Province in recent 40 years and its probable mechanisms",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028829832&partnerID=40&md5=0c15d3218654dbf8b0386dfd36acb396","The analysis of temperature variation trends at 160 meteorological stations in China from 1951 to 1992 showed that a relatively large area of China became warm in recent years, but there still existed an obvious cooling center in Sichuan basin. We also analyzed the variation trends of some meteorological factors which could probably cause this cooling, and the results indicated that the global solar radiation, the insolation duration and visual range decreased sharply in recent years, but the cloud amount changed slightly in Sichuan basin. We also found that the decrease of surface solar radiation caused by the increase of the anthropogenic aerosols' backscattering in the lower troposphere was a notable reason for the cooling of Sichuan basin in recent years. We also confirmed this conclusion by using of a one-dimensional climate model. -Authors"
"57206526682;","The Local Surface Energy Balance of the Ecology Glacier, King George Island, Antarctica: Measurements and modelling",1995,"10.1017/S0954102095000435","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029501462&doi=10.1017%2fS0954102095000435&partnerID=40&md5=de8acbd850ec9a10e4cbdb8adce34ac9","Meteorological measurements performed during the austral summer of 1990–91 are used to evaluate the surface energy balance and ablation at an elevation of 100 m asl on the Ecology Glacier, which is an outlet glacier of the main ice cap of King George Island, Antarctica. Strong, gusty westerly winds prevail, although occasional south-easterly winds from the Weddell Sea reach the island. Generally, the climate can be characterized as relatively warm and humid with mean summer temperatures well above 0°C. As a result, considerable ablation (0.75 m water equivalent per month) takes place in the lower parts of the Ecology Glacier. The surface energy balance and ablation are calculated using a model with input from meteorological data. In spite of the large amount of cloud (0.83), solar radiation provided most of the energy used for melting (70.3 W m-2) The longwave radiation, sensible heat flux and latent heat flux contributed -9.5, 27.4 and 7.4 W m-2respectively. Calculations show that a temperature rise of 1°C increases the ablation by almost 15%. This indicates that the ice caps and glaciers currently present on the subantarctic islands and the Antarctic Peninsula may be quite sensitive to climate change. © 1995, Antarctic Science Ltd. All rights reserved."
"6602187911;7004909806;7202754530;6603958663;","Sensitivity to prescribed changes in sea surface temperature and sea ice in doubled carbon dioxide experiments",1995,"10.1007/BF00208759","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029510752&doi=10.1007%2fBF00208759&partnerID=40&md5=fd529ccd5debf59a79b0ac189500c94e","Time sclice experiments are performed with the atmospheric GCM ARPEGE, developed at Météo-France, to study the impact to increases in the atmospheric carbon dioxide. This spectral model runs at T42 horizontal resolution with 30 vertical layers including a comprehensive tropospheric and stratospheric resolution and a prognostic parameterization of the ozone mixing ratio. The model is forced in a 5-year control run by climatological SSTs and sea-ice extents in order to obtain an accurate simulation of the present-day climate. Two perturbed runs are performed using SSTs and sea-ice extents for doubled CO2 concentration, obtained from transient runs performed by two coupled atmospheric-oceanic models run at the Max Planck Institute (MPI) in Hamburg and the Hadley Centre (HC). A global surface temperature warming of 1.6 K is obtained with the MPI SST anomalies and 1.9 K with the HC SST anomalies. The precipitation rate increases by 4.2% (and 4.7%). The features obtained in the stratosphere (a cooling increasing with the altitude and an increase in the ozone mixing ratio) are not sensitive to the oceanic forcing. On the contrary, the anomalies in the troposphere such as a warming increasing with altitude, an acceleration of westerly jets and a raised cloud height, depend on the oceanic forcing imposed in the two perturbed runs. Special attention is given to continental areas where the impact of the oceanic forcing is studied over eight regions around the globe. Regions sensitive to oceanic forcing such as Europe are identified in contrast with areas where the patterns are driven by land-surface physical processes, such as over continental Asia. Finally, the Köppen classification is applied to the climate simulated in the three experiments. Both doubled CO2 runs show the same predominance of global warming over precipitation changes in the Kbppen analyses. © 1995, Springer-Verlag. All rights reserved."
"7006356035;27267529400;","Development of the new ccc/gcm longwave radiation model for extension into the middle atmosphere",1995,"10.1080/07055900.1995.9649543","https://www.scopus.com/inward/record.uri?eid=2-s2.0-21844499677&doi=10.1080%2f07055900.1995.9649543&partnerID=40&md5=49981a6c78ae205d79dc2fa40d697d5b","A new infrared (IR) radiation scheme for extending the CCC/GCM (Canadian Climate Center General Circulation Model) into the middle atmosphere is proposed. It combines the previous CCC/GCM radiation scheme including the effects of H2O, CO2, O3, CH4, N2O, CFC11 and CFC12, clouds and aerosols, with a new computationally efficient matrix parameterization for the cooling rate in the middle atmosphere for both LTE (local thermodynamic equilibrium) and non-LTE layers. The matrix parameterization includes the effects of both the 15 μm CO2 and the 9.6 μm O3 bands and provides a proper lower boundary condition for the non-LTE recurrence formula. The new scheme shows satisfactory agreement with line-by-line calculations. The absolute error does not exceed 0.8? day-1for vastly different atmospheric conditions. Introducing the new radiation module into the CCC/GCM results in deviations of the simulated temperature from the CIRA-1986 model of not more than 10? throughout most of the altitude-latitude domain. © Taylor &amp; Francis Group, LLC."
"55678879300;","Transient response of the Hadley Centre coupled ocean-atmosphere model to increasing carbon dioxide. Part III: analysis of global- mean response using simple models",1995,"10.1175/1520-0442(1995)008<0496:TROTHC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029501837&doi=10.1175%2f1520-0442%281995%29008%3c0496%3aTROTHC%3e2.0.CO%3b2&partnerID=40&md5=f3972720a0c51b5b4c7ee923093ca716","The roles of surface, atmospheric, and oceanic feedbacks in controlling the global-mean transient response of a coupled ocean-atmosphere general circulation model to increasing carbon dioxide are investigated. The land-sea contrast in the surface warming is explained almost entirely by the shortwave radiative feedbacks associated with changes in cloud and surface albedo. The oceanic thermal inertia delays the response; however, the initial delay is enhanced by increases in Antarctic sea-ice cover, which substantially reduce the effective climate sensitivity of the model in the first half of the 75-year experiment. However, inclusion of the direct forcing due to anthropogenic tropospheric sulphate aerosol eliminates the land/sea contrast in the response at 1990, leaving the simulated warming over land slightly below the observed value, although the rapid warming observed during the 1980s is well reproduced. -from Author"
"6602974079;7103194443;","Generalized additive models versus linear regression in generating probabilistic MOS forecasts of aviation weather parameters",1995,"10.1175/1520-0434(1995)010<0669:GAMVLR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029431587&doi=10.1175%2f1520-0434%281995%29010%3c0669%3aGAMVLR%3e2.0.CO%3b2&partnerID=40&md5=6f10f18900cb1454a09c4e42d8f1e7a4","The skill of probabilistic Model Output Statistics forecasts generated from Generalized Additive Models (GAM) is compared to that of traditional multiple linear regression techniques. GAM is a nonparametric tool that makes use of the data to automatically estimate the appropriate functional (curvative) relationship for each predictor term. Forecast equations for each statistical technique are developed for nine regions encompassing a total of 90 stations in the northeastern US. Three parameters (cloud amount, ceiling height, and visibility) are forecast for eight thresholds and two lead times (12 h and 24 h). The developmental dataset consists of limited-area fine-mesh numerical model output and surface observations for the period 1984-1989. Verification on 3 yr (1990-1992) of independent data indicates a clear and consistent superiority of the GAM model over linear regression, with mean square errors generally 3%-4% lower and lead time gains of 2-9 h."
"7102948268;","Analysis of German climatic variations during the period of instrumental record",1995,"10.1029/94GL02995","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028794880&doi=10.1029%2f94GL02995&partnerID=40&md5=c92db37d700e355f04df405f8929a737","The purpose of this investigation is to characterize climatic changes that have occurred in Germany based on historical observational records. Analyses show that mean annual temperatures in Germany have warmed by 0.66°C over the past 140 years with most of this warming occurring during the low‐sun seasons and early in this century. Very long‐term records from three German stations, which are similar to long‐term data from surrounding stations, reveal no warming over the past 200+ years. All of the temperature records show the period near 1890 to be anomalously cool. As with many other parts of the world, the diurnal temperature range in Germany has declined slightly while precipitation totals and cloud cover have increased; precipitation and the diurnal temperature range have a strong and negative correlation over the period 1950–1989. Historical climatic variations in Germany generally are consistent with patterns found for other mid‐latitude locations around the world. Copyright 1995 by the American Geophysical Union."
"7004055357;7004247172;7004357341;","A comparison of selected models for estimating cable icing",1995,"10.1016/0169-8095(94)00036-D","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029503803&doi=10.1016%2f0169-8095%2894%2900036-D&partnerID=40&md5=6f8e29eed9a23e4b5eeb73642d604528","In many cold climate countries, it is becoming increasingly important to monitor transmission line icing. Indeed, by knowing in advance of localized danger for icing overloads, electric utilities can take measures in time to prevent generalized failure of the power transmission network. Recently in Canada, a study was made to compare the estimation of a few icing models working from meteorological data in estimating ice loads for freezing rain events. The models tested were using only standard meteorological parameters, i.e. wind speed and direction, temperature and precipitation rate. This study has shown that standard meteorological parameters can only achieve very limited accuracy, especially for longer icing events. However, with the help of an additional instrument monitoring the icing rate intensity, a significant improvement in model prediction might be achieved. The icing rate meter (IRM) which counts icing and de-icing cycles per unit time on a standard probe can be used to estimate the icing intensity. A cable icing estimation is then made by taking into consideration the accretion size, temperature, wind speed and direction, and precipitation rate. In this paper, a comparison is made between the predictions of two previously tested models (one obtained and the other reconstructed from their description in the public literature) and of a model based on the icing rate meter readings. The models are tested against nineteen events recorded on an icing test line at Mt. Valin, Canada, during the winter season 1991-1992. These events are mostly rime resulting from in-cloud icing. However, freezing rain and wet snow events were also recorded. Results indicate that a significant improvement in the estimation is attained by using the icing rate meter data together with the other standard meteorological parameters. © 1995."
"7101983091;7003674132;","Biological invasion on an oceanic island mountain: Do alien plant species have wider ecological ranges than native species?",1995,"10.2307/3236436","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028995330&doi=10.2307%2f3236436&partnerID=40&md5=cb0b5966abbb41de158fa29641f1e753","Abstract. Spatial distribution patterns of alien plant species were compared with those of native species on a windward slope of Mt. Haleakala (3055 m). Oceanic islands are considered susceptible to biological invasion, and this study numerically tested this circumstantial evidence with the following questions: Are all habitats equally susceptible; and, do successful invaders have wider realized niches than natives? The mountain slope consists of three distinct altitudinal bioclimatic zones (hot moist lowland, wet montane cloud, and cool arid high‐altitude zones). Ordination indicated that alien species' ranges and population expansions were clustered in the lowland and high‐altitude zones. The lowland zone had been subjected to natural canopy dieback, and the high‐altitude zone to grazing by domestic and feral ungulates. By contrast, the montane cloud forest was relatively intact in terms of number and cover of native species. Thus, susceptibility to alien invasion clearly differed among zones, and the primary causes seemed to be the obvious disturbance factors. The mean ecological range along the altitude‐rainfall gradient was significantly (P < 0.05) greater for native than for alien species in most life‐form groups. The reasons for the greater number of climate generalists among the natives vs. the range‐restricted aliens appear to be related to: (1) the pre‐alien condition with a depauperate flora which allowed for ‘ecological release’ of successful native colonizers, and (2) the climatic pre‐adaptation of alien invaders which restricts them from penetrating over a broader spectrum of climatic zones in a floristic matrix subjected to increasing interspecific competition. 1995 IAVS ‐ the International Association of Vegetation Science"
"7003935733;55167157900;","The NOAA pathfinder program",1995,"10.1016/0273-1177(95)00373-M","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028830257&doi=10.1016%2f0273-1177%2895%2900373-M&partnerID=40&md5=07728ab651ff98908683cfc4b47bc09c","The National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA) are participating in a joint program to generate ""research/climate quality"" data sets from archived operational satellite observations dating as far back as 1978. The raw instrumental observations have been transcribed from thousands of magnetic tapes to more accessible, high density storage media and are being reprocessed using the best available calibration information and community consensus algorithms. Under the distributed processing arrangements, NOAA is responsible for: Path C products from the TIROS Operational Vertical Sounder (TOVS), which consist of clear radiances and deep layer mean temperatures independent of a priori information; atmosphere products from the Advanced Very High Resolution Radiometer (AVHRR), including cloud, Earth radiation budget, and aerosol variables; and, together with NASA, reduced resolution radiances from the GOES satellites consisting of hourly 8 km and 70 km statistical data sets. The status of the NOAA processing effort is described and examples of the data sets are presented. © 1995."
"7005659017;14520880100;55491661100;7004154626;","Real-time monitoring of atmospheric aerosols using a computer-controlled lidar",1995,"10.1016/1352-2310(94)00355-O","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028991291&doi=10.1016%2f1352-2310%2894%2900355-O&partnerID=40&md5=4d644a1233ebb107d1dcdbd3d1f2f205","Regular monitoring of aerosol parameters during nighttime in the tropical urban lower atmosphere using a tunable, continuous wave, bistatic argon ion laser radar (lidar) system was initiated at the Indian Institute of Tropical Meteorology, Pune (18°32′N, 73°N51′E), India in 1986. So far, the measurements have been made from manual operation of the lidar which consumes a lot of time and inhibits interpretation of results immediately after completion of the experiment. In order to improve and expedite the data acquisition-processing and to avoid extra manual work to a considerable extent, the lidar has recently been made fully automatic. This paper discusses the on-line control and digital data system that provides real-time acquisition, analysis and display of lidar data. The improvements in the data quality and application of the system to the real-time observation of various features connected with atmospheric aerosol variations in both space and time are presented. The previously used lidar data acquisition and handling techniques and those of the present auto-mode operation are compared. Such real-time aerosol observations on a long-term basis are expected to lead to a better understanding of the optical properties of aerosols and their interaction with clouds and climate and will hopefully add to the global monitoring efforts and attempts at incorporating aerosols into climate models. © 1995."
"7201888345;","Dynamical processes of transfer at the sea surface",1995,"10.1016/0079-6611(95)80002-B","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029478385&doi=10.1016%2f0079-6611%2895%2980002-B&partnerID=40&md5=8353410f690ebfc4ed8b6761817f3b52","This review describes the dynamical processes of transport from, and immediately below, the sea surface, particularly those which involve convergence and the separation of flow, and which result in the renewal of surface water at horizontal scales ranging from millimeters to hundreds of meters. Turbulence at or near the sea surface derives from several processes - breaking waves and the bubbles they may produce, precipitation and spray, Langmuir circulation and thermal convection, and turbulence which is internally generated by shear. Interest in the subject derives from the requirements to predict air-sea fluxes of heat, momentum and gases, to develop climate models, to interpret satellite images of the sea surface, including those of ship wakes, and to predict upper ocean structure, including mixing layer depth, in models of phytoplankton blooms and acoustic propagation. The general effect of subsurface turbulence on the sea surface, and the effects of surfactants, is described, and each process is discussed in turn. Laboratory experiments and theoretical studies have contributed particularly to the understanding of the interaction of vortices and turbulence with the surface and to the consequences of breaking waves. They point to the development of instability in the flow ahead of steep waves carrying parasitic capillary waves, which may contribute to the onset of flow separation on the leading face of the waves and the development of a rotor, or 'roller', below the wave crest, shown most clearly in the pattern of streamlines in a frame of reference moving forward with the wave. The conditions near the flow separation line on the wave surface ahead of the rotor may be similar to those produced by vortices approaching a free surface. Detailed observation of breaking waves at sea is lacking, but some progress has been made using acoustics to detect the clouds of subsurface bubbles formed by the larger breakers and the depth to which they penetrate. The possible importance of three-dimensional effects in breaking waves is discussed, and a conjectural sketch of the surface flow field and the surface separation and reattachment pattern, following a plunging breaker, is described. Recent observations show elevated levels of turbulence close to the sea surface. The depth of the layer in which this occurs is shown to be consistent with information derived from sonar studies of the depth of bubble clouds, the observed frequency of breaking waves and laboratory observations of breaking waves. Rain is known to 'knock down the sea', reducing the frequency and intensity of breaking waves. The precise mechanics of the phenomena are uncertain but an enhancement of near-surface turbulence and the damping of short surface gravity waves has been observed in laboratory experiments. Langmuir circulation, temperature ramps and convection, all associated with coherent structures, are processes which mix the upper ocean, although their relative importance is unknown. Connections between studies with quite disparate motivations are found to help provide descriptions of the upper ocean processes and estimates of the time scale of surface renewal associated with each of the processes identified. Many quantities being transferred across the sea surface appear to be transported by dynamical processes of scale much smaller than that of the dominant surface waves, although their subsequent diffusion in the mixing layer may be strongly influenced by the larger scale processes. Further careful measurements in the laboratory and at sea are required to quantify the fluxes associated with the processes and to relate them to external parameters such as wind speed. © 1995."
"56673482900;8321530600;","An earth-gridded SSM/I data set for cryospheric studies and global change monitoring",1995,"10.1016/0273-1177(95)00397-W","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028873649&doi=10.1016%2f0273-1177%2895%2900397-W&partnerID=40&md5=42c342d452d31f3184800f695f460c6c","The National Snow and Ice Data Center (NSIDC) has distributed DMSP Special Sensor Microwave Imager (SSM/I) brightness temperature grids for the Polar Regions on CD-ROM since 1987. In order to expand this product to include all potential snow covered regions, the area of coverage is now global. The format for the global SSM/I data set is the Equal Area SSM/I Earth Grid (EASE-Grid) developed at NSIDC. The EASE-Grid has been selected as the format for the NASA/NOAA Pathfinder Program Level 3 Products which include both SSM/I and SMMR (Scanning Multichannel Microwave Radiometer) data (1978-1987). Providing both data sets in the EASE-Grid will result in a 15 year time-series of satellite passive microwave data in a common format. The extent and variability of seasonal snow cover is recognized to be an important parameter in climate and hydrologic systems and trends in snow cover serve as an indicator of global climatic changes. Passive microwave data from satellites afford the possibility to monitor temporal and spatial variations in snow cover on the global scale, avoiding the problems of cloud cover and darkness. NSIDC is developing the capability to produce daily snow products from the DMSP-SSM/I satellite with a spatial resolution of 25 km. In order to provide a standard environment in which to validate SSM/I algorithm output, it is necessary to assemble baseline data sets using other, more direct, methods of measurement. NSIDC has compiled a validation data set of surface station measurements for the northern hemisphere with specific focus on the United States, Canada, and the former Soviet Union. Digital image substraction is applied to compare the surface station and satellite measurements. © 1995."
"57208765879;7003830856;","Remote sensing the susceptibility of cloud albedo to changes in drop concentration",1994,"10.1016/0169-8095(94)90082-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0003540267&doi=10.1016%2f0169-8095%2894%2990082-5&partnerID=40&md5=3dcfec171006cb0c835944fcf0058c01","The role of clouds in reflecting solar radiation to space and thereby reducing surface heating is of critical importance to climate. Combustion processes that produce green-house gases also increase cloud condensation nuclei (CCN) concentrations which in turn increase cloud drop concentrations and thereby cloud albedo. A calculation of cloud susceptibility, defined in this work as the increase in albedo resulting from the addition of one cloud drop per cubic centimeter (as cloud liquid water content remains constant), is made through satellite remote sensing of cloud drop radius and optical thickness. The remote technique uses spectral channels of the Advance Very High Resolution Radiometer (AVHRR) instrument on board the NOAA polar orbiting satellites. An approximation for the effect of the atmosphere on the signal received by the AVHRR is included in the analysis. Marine stratus clouds, as well as being important modifiers of climate, are cleaner than continental clouds an so likely to be of higher susceptibility. Analysis of several stratus scenes, including some containing ship tracks, supports this expectation. © 1994."
"7401657564;7403079681;","A universal regression retrieval method of the ground-based microwave remote sensing of precipitable water vapor and path-integrated cloud liquid water content",1994,"10.1016/0169-8095(94)90099-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0542439686&doi=10.1016%2f0169-8095%2894%2990099-X&partnerID=40&md5=e0671d4f2cfedafed76e716b986694eb","An attempt has been made to obtain two respective universal equations, applying to different regions, elevations and seasons in the world, for remote sensing the atmospheric precipitable water vapor (Q) and the path-integrated cloud liquid water content (L) by using a ground-based dual-frequency (20.6 and 31.4 GHz) microwave radiometer (GBDFMR). To do so, a set of a priori radiosonde data with a total of 2742 cases was selected in typical seasons (winter and summer) at eight radiosonde stations (Beijing, Guangzhou, Guam, Yap, Lhasa, Zhangye, Nagqu and Lijiang) typical of the climates of mid-latitude mainland, tropical marine, plain, plateau and mountain, respectively. A cloud model was constructed in a way much the same as that by Decker et al. (1978, pp. 1789-1790) and an ensemble of cloudy- and clear-day mixed samples were elaborately constructed. Based on this ensemble, numerical simulation was done for each case by using a microwave radiation transfer model to compute the radiometric brightness temperatures Tb1 and Tb2 as well as the dependent variables L and Q. The simulated Tb1 and Tb2 together with surface air temperature, surface humidity, surface pressure, the index of clear or cloudy day, cloud base height and their combinations were used as the candidates for the predictors of multivariate regression. The stepwise regression and ridge regression techniques ensure the two resepective resultant regression equations to be steady, optimal and feasible for retrieval of L and Q. The tests on these equations by using temporal and spatial extrapolation samples with total of 1020 cases show that they have quite good accuracies for predicting the Q and L and can be used operationally. This work suggests broad prospect in the application of GBDFMR in cloud liquid water and precipitable water vapor measurements. © 1994."
"24785682400;6505757723;36927872500;","Numerical simulation for the impact of deforestation on climate in china and its neighboring regions",1994,"10.1007/BF02666547","https://www.scopus.com/inward/record.uri?eid=2-s2.0-51249166354&doi=10.1007%2fBF02666547&partnerID=40&md5=88a14f59f27223bb582c1476fa5152e8","In this paper, the CCMOB model is used to study the effect of the deforestation on the climate of China and its neighboring regions. On the assumption that the forest in China would be replaced by the vegetation(such as grassland), the distribution of the albedo changed was calculated. The initial fields used were taken from the FGGE zonal mean data on 16 July, 1979. In the control simulation, the observed albedo data were used to modify the physical parameters of the original model. The control and sensitive experiments were run each for 210 days, in which the external forcing fields were fixed in July. As a result, we find that the East Asian Monsoon, Hadley cell and troposphere easterly jet are weakened for the deforestation in China. The precipitation and cloud amount over China are also decreased. The changes in evaporation and surface temperature are small. The results also show that the deforestation in China exerts a remarkable effect on the climate in the neighboring regions of China. © 1994 Advances in Atmospheric Sciences."
"13806362800;7403233451;","Sea‐ice dynamics and co2 sensitivity in a global climate model",1994,"10.1080/07055900.1994.9649506","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028591316&doi=10.1080%2f07055900.1994.9649506&partnerID=40&md5=5cc8881dc6af392a50f2d006722cfa69","Present‐day results and CO2 sensitivity are described for two versions of a global climate model (genesis) with and without sea‐ice dynamics. Sea‐ice dynamics is modelled using the cavitating‐fluid method of Flato and Hibler (1990, 1992). The atmospheric general circulation model originated from the NCAR Community Climate Model version 1, but is heavily modified to include new treatments of clouds, penetrative convection, planetary boundary‐layer mixing, solar radiation, the diurnal cycle and the semi‐Lagrangian transport of water vapour. The surface models include an explicit model of vegetation (similar to BATS and SiB), multilayer models of soil, snow and sea ice, and a slab ocean mixed layer.When sea‐ice dynamics is turned off, the CO2‐induced warming increases drastically around ∼60–80°S in winter and spring. This is due to the much greater (and unrealistic) compactness of the Antarctic ice cover without dynamics, which is reduced considerably when CO2 is doubled and exposes more open ocean to the atmosphere. With dynamics, the winter ice is already quite dispersed for 1 × CO2 so that its compactness does not decrease as much when CO2 is doubled. © 1994 Taylor & Francis Group, LLC."
"57216996866;","Photochemistry of clouds, fogs, and aerosols",1994,"10.1021/es00054a001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022750985&doi=10.1021%2fes00054a001&partnerID=40&md5=eb85aa4da778d6c79736ec9eaeac911a",[No abstract available]
"55684491100;","On the effect of emissions from aircraft engines on the state of the atmosphere",1994,"10.1007/s00585-994-0365-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984408941&doi=10.1007%2fs00585-994-0365-0&partnerID=40&md5=83d86c536930e0ae0dd97aa235850848","Emissions from aircraft engines include carbon dioxide, water vapour, nitrogen oxides, sulphur components and various other gases and particles. Such emissions from high-flying global civil subsonic air traffic may cause anthropogenic climate changes by an increase of ozone and cloudiness in the upper troposphere, and by an enhanced greenhouse effect. The absolute emissions by air traffic are small (a few percent of the total) compared to surface emissions. However, the greenhouse effect of emitted water and of nitrogen oxides at cruise altitude is potentially large compared to that of the same emissions near the earth’s surface because of relatively large residence times at flight altitudes, low background concentrations, low temperature, and large radiative efficiency. Model computations indicate that emission of nitrogen oxides has doubled the background concentration in the upper troposphere between 40°N and 60°N. Models also indicate that this causes an increase of ozone by about 5-20%. Regionally, the observed annual mean change in cloudiness is 0.4%. It is estimated that the resultant greenhouse effect of changes in ozone and thin cirrus cloud cover causes a climatic surface temperature change of 0.01-0.1 K. These temperature changes are small compared to the natural variability. Recent research indicates that the emissions at cruise altitude may increase the amount of stratospheric aerosols and polar stratospheric clouds and thereby have an impact on the atmospheric environment. Air traffic is increasing about 5-6% per year, fuel consumption by about 3%, hence the effects of the related emissions are expected to grow. This paper surveys the state of knowledge and describes several results from recent and ongoing research. © European Geosciences Union 1994."
"6603468473;7006393267;6602699701;","Cloud optical properties at Bergen (Norway) based on the analysis of long-term solar irradiance records",1994,"10.1007/BF00864904","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028578361&doi=10.1007%2fBF00864904&partnerID=40&md5=5d32eabfaed68da8bbadf9185c6367bd","Ground-based measurements of incoming solar irradiance and cloud observations during a 26 year period (1965-1990) at Bergen, Norway were used in conjunction with a comprehensive radiation model to infer the cloud optical depth τ under completely overcast conditions. Month-to-month and year-to-year (April through October) statistics of the cloud optical depth and observed cloud forms are presented. Some climate-related features, specifically, diurnal and seasonal variabilities in τ are examined. The effects of local cloudiness are pointed out and discussed. There appears to be a slight trend towards increasing cloud optical depth at noon during the warm period of the year. The possible uncertainties due to unknown size of cloud droplets are analyzed by model simulations. Possible directions for future research are suggested provided more meteorological and/or satellite information is available. © 1994 Springer-Verlag."
"6603125868;7004167838;6603858313;","Remote sensing of cloud liquid water",1994,"10.1007/BF01030057","https://www.scopus.com/inward/record.uri?eid=2-s2.0-21844516513&doi=10.1007%2fBF01030057&partnerID=40&md5=0aeb2a028c748b5428d2101d2eec107b","A method is presented to infer cloud liquid water path (LWP in kg/m2) over the ocean from passive microwave measurements of SSM/I. The algorithm to retrieve LWP is based on simulated satellite observations. They are calculated with a radiative transfer model applied to about 3000 radiosonde ascents over the Atlantic Ocean. Since radiosonde observations do not contain direct information about cloud water and ice, these parameters are parameterized based on relative humidity and temperature using modified adiabatic liquid water density profiles. A multiple linear regression is applied to the simulated radiances and the calculated LWP to derive the algorithm. The retrieval accuracy based on the regression analysis including instrumental noise is 0.03 kg/m2. Validation of the LWP-algorithm was pursued through a comparison with measurements of a ground-based 33 GHzmicrowave radiometer on board of R.V. ""Poseidon"" during the International Cirrus Experiment 1989 at the North Sea (ICE'89). The LWP values agree within the range of uncertainty caused by the different sampling characteristics of the observing systems. The retrieval accuracy for clear-sky cases determined using colocated METEOSAT data over the North Sea is 0.037 kg/m2 and confirms the accuracy estimated from regression analysis for the low liquid water cases. The algorithm was used to derive maps of monthly mean LWP over the Atlantic Ocean. As an example the Octobers of the 5 years 1987-1991 were selected to demonstrate the interannual variability of LWP. The results were compared with the cloud water content produced by the climate model ECHAM-T2 from the Max-Planck-Institut Hamburg. Observations during ICE'89 were used to check the accuracy of the applied radiative transfer model. Brightness temperatures were calculated from radiosonde ascents launched during the overpass of DMSP-F8 in cloud-free situations. The channel-dependent differences range from about -2 to 3 K. The possibility to identify different cloud types using microwave and infrared observations was examined. The main conclusion is that simultaneous microwave and infrared measurements enable the separation of dense cirrus and cirrus with underlying water clouds. A classification of clouds with respect to their top heights and LWP was carried out using a combination of SSM/I derived LWP and simultaneously recorded Meteosat IR-data during ICE'89. © 1994 Springer-Verlag."
"6701599239;6604000335;57190928076;6603892183;","The impact of cloud inhomogeneities on the Earth radiation budget: The 14 October 1989 I.C.E. convective cloud case study",1994,"10.1007/s00585-994-0240-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984399699&doi=10.1007%2fs00585-994-0240-z&partnerID=40&md5=86ae4ef303a5e8c5626c6b5610e69eff","Through their multiple interactions with radiation, clouds have an important impact on the climate. Nonetheless, the simulation of clouds in climate models is still coarse. The present evolution of modeling tends to a more realistic representation of the liquid water content; thus the problem of its subgrid scale distribution is crucial. For a convective cloud field observed during ICE 89, Landsat TM data (resolution: 30m) have been analyzed in order to quantify the respective influences of both the horizontal distribution of liquid water content and cloud shape on the Earth radiation budget. The cloud field was found to be rather well-represented by a stochastic distribution of hemi-ellipsoidal clouds whose horizontal aspect ratio is close to 2 and whose vertical aspect ratio decreases as the cloud cell area increases. For that particular cloud field, neglecting the influence of the cloud shape leads to an over-estimate of the outgoing longwave flux; in the shortwave, it leads to an over-estimate of the reflected flux for high solar elevations but strongly depends on cloud cell orientations for low elevations. On the other hand, neglecting the influence of cloud size distribution leads to systematic over-estimate of their impact on the shortwave radiation whereas the effect is close to zero in the thermal range. The overall effect of the heterogeneities is estimated to be of the order of 10 W m-2 for the conditions of that Landsat picture (solar zenith angle 65°, cloud cover 70%); it might reach 40 W m-2 for an overhead sun and overcast cloud conditions. © European Geosciences Union 1994."
"7003430284;7007108728;","On the relationship between sulfate and cloud droplet number concentrations",1994,"10.1175/1520-0442(1994)007<0206:OTRBSA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028174477&doi=10.1175%2f1520-0442%281994%29007%3c0206%3aOTRBSA%3e2.0.CO%3b2&partnerID=40&md5=7780190c399588dce3d9d818788ea1b5","Comparisons are drawn between the aerosol cloud microphysical theory implicit in the modeling of Kaufman et al. and the cloud droplet and cloud water sulfate concentrations of Leaitch et al. for the purpose of helping to understand the effect of sulfate particles on climate through cloud modification. In terms of the range of possibilities and prospects for future climate given by Kaufman et al. for the effect of sulfur on cloud albedo, the data favor the possibility of stronger cooling. Scatter in the data makes it impossible to constrain model parameters; however, the comparisons suggest that there may not be a universal relationship, and that the uncertainties involved in trying to model this process are large. -Authors"
"7201361035;","The influence of clouds on earth radiation budget - a regional study: The North Sea",1994,"10.1016/0273-1177(94)90352-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028264577&doi=10.1016%2f0273-1177%2894%2990352-2&partnerID=40&md5=9cc527ede3b764f10a940c0ce80a47cd","The influence of clouds over the North Sea on climate is investigated by analyzing NOAA AVHRR data. The main interest is on high clouds due to their ambivalent behaviour in the radiation field. After a cloud classification, especially for high clouds, and the determination of cloud optical properties, the obtained information was applied to calculate the cloud-climate efficiency. This index is similar to the cloud forcing, but is valid for an individual classified satellite image pixel. The cloud forcing is the sum of the cloud-climate efficiencies over an area. Using NOAA-AVHRR data the annual cycle (October 1989, October 1990, April 1991 - July 1992) of cloud forcing at the top of atmosphere were calculated. Due to the strong dependence on solar insolation, high clouds with the same optical properties lead to an heating or a cooling of the earth/atmosphere system. For thin cirrus clouds the heating effect is well correlated with an increase of the surface temperature. A further approach to compare the increasing/decreasing cloud forcing with an analysis of relative topography 300/1000 hPa shows that an increase is positively correlated with an increase of the temperature in this layer. © 1993."
"7005513582;","Sensitivity of a GCM climate simulation to differences in continental versus maritime cloud drop size",1994,"10.1029/94jd01117","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028601735&doi=10.1029%2f94jd01117&partnerID=40&md5=0e24e7bc344295fb0bfc9c2606863286","The latest version of the NCAR Community Climate Model (CCM2) is used to explore the sensitivity of differentiating between continental and maritime re on the simulated climate. The results of this study indicate that the smaller drop size over continents leads to a reduction of surface-absorbed solar radiation from 20 to 60 W m-2. This reduction in surface solar flux leads to a cooling of the continents by up to -3.5 K. The reduction in surface solar flux and temperature also leads to a reduction in latent heat flux and precipitation over land. -from Author"
"57206330745;7403974034;","Absorption feedback in stratocumulus clouds influence on cloud top albedo",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028592205&partnerID=40&md5=d67875045bf442561797b0d45498b068","This paper proposes a feedback mechanism which modifies the enhancement of cloud top albedo expected from an increased concentration of cloud condensation nuclei (CCN). The mechanism is based on the thermodynamic tendency of the cloud to stabilize itself against changes in the absorption of solar radiation. For optically thin clouds, this absorption feedback leads to a reduction in the anticipated albedo enhancement, while for optically thick clouds, an amplification of the albedo enhancement is predicted. The likely impact of this effect on the radiative forcing of climate due to changes in CCN and hence cloud top albedo is discussed. -Authors"
"57206330745;7403974034;","Absorption feedback in stratocumulus clouds Influence on cloud top albedo",1994,"10.1034/j.1600-0870.1994.00001.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981636132&doi=10.1034%2fj.1600-0870.1994.00001.x&partnerID=40&md5=47730eb0397d5cb8b375c451dbda45d2","This paper proposes a feedback mechanism which modifies the enhancement of cloud top albedo expected from an increased concentration of cloud condensation nuclei (CCN). The mechanism is based on the thermodynamic tendency of the cloud to stabilize itself against changes in the absorption of solar radiation. For optically thin clouds, this absorption feedback leads to a reduction in the anticipated albedo enhancement, while for optically thick clouds, an amplification of the albedo enhancement is predicted. The likely impact of this effect on the radiative forcing of climate due to changes in CCN and hence cloud top albedo is discussed. Copyright © 1994, Wiley Blackwell. All rights reserved"
"55745955800;7005814217;7005513582;7005070958;","Diagnostic study of climate feedback processes in atmospheric general circulation models",1994,"10.1029/93JD03523","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028250154&doi=10.1029%2f93JD03523&partnerID=40&md5=902966fa9aa1f86c8030905e1104c795","A method is proposed to diagnose climate feedbacks of water vapor, temperature lapse-rate, and cloud variations in atmospheric general circulation models. It is then applied to study differences in sensitivity of the National Center for Atmospheric Research community climate model (CCM2) and two hybrid versions of CCM2 with different cumulus-convection schemes. Water vapor feedback and temperature lapse-rate feedback differ among the models due to different efficiencies of heat and moisture transport by cumulus convections. A large compensation occurs between water vapor feedback and temperature lapse-rate feedback. This leads to similar clear-sky sensitivities in the models. -from Authors"
"7404240633;7004942632;","Studies of the radiative properties of ice and mixed‐phase clouds",1994,"10.1002/qj.49712051508","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028193820&doi=10.1002%2fqj.49712051508&partnerID=40&md5=5276166eb295c3653b0b318d082e0e43","Radiative parametrizations for both ice and water clouds are developed in terms of liquid/ice water content, based on Mie scattering theory. For ice crystals the application of Mie theory is guided by the hexagonal‐crystal/equivalent‐spheres comparison of Takano and Liou. These parametrizations are extensively tested against measurements from aircraft and are shown to perform satisfactorily, although corrections for unobserved small crystals and the effect of crystal shape are large and not currently well defined. The parametrizations are then used to investigate the effect of mixed‐phase clouds on radiative transfer. It is found that, because the radiative properties of ice crystals and liquid droplets are significantly different, the radiative properties of mixed‐phase clouds cannot be simulated successfully if the ice in clouds is converted into liquid water. Both the albedo and the rate of change of albedo with ice fraction are significantly dependent on the method by which the phases are mixed; these factors may be of especial importance in climate‐sensitivity experiments that incorporate mixed‐phase clouds. The presence of ice in clouds below the cirrus level is often ignored in climate‐model and radiation‐budget studies. The calculations presented here indicate that this neglect may lead to a serious bias in cloud albedo for a given path of condensed water. Copyright © 1994 Royal Meteorological Society"
"56250708000;7404350314;7102224078;6701752077;","The potential of satellite remote sensing of snow over Great Britain in relation to cloud cover",1994,"10.2166/nh.1994.0018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028262682&doi=10.2166%2fnh.1994.0018&partnerID=40&md5=d9aa2db3b5a03d49723cb84d882166ed","Whilst satellite monitoring of snow cover is already operational in some countries, the maritime climate of the United Kingdom poses special problems for assessment of snow cover by satellite, including the short snow duration, its intermittent occurrence and associated conditions of cloud. Both satellite and ground-based observations of cloud have been used to assess the limitations imposed by cloud over broad regions and also for individual sites at different elevations and during periods of snow accumulation, stability ad ablation. It is concluded that satellite sensing based on visible and infrared images alone is restricted by cloud cover, but can often provide helpful ancillary information in support of ground based measurements and satellite images from other spectral bands. -Authors"
"7005513582;7005814217;6603451961;","The simulated Earth radiation budget of the National Center for Atmospheric Research community climate model CCM2 and comparisons with the Earth Radiation Budget Experiment (ERBE)",1994,"10.1029/94jd00941","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028581204&doi=10.1029%2f94jd00941&partnerID=40&md5=4a9a125714149c078383a606502d238b","In general, the radiation budget of CCM2 is in better agreement with the ERBE data than previous versions of the CCM. In particular, the latitudinal structure of cloud radiative forcing is much improved over CCM1. The phase of the simulated seasonal cycle in top of atmosphere radiation quantities is well represented. In the tropics the magnitude is in good agreement with the observations from ERBE. In the Northern Hemisphere summer the model radiative properties contain a bias. In the shortwave spectral region the clouds reflect an insufficient amount of solar radiation, while in the longwave, too much radiation is emitted to space. These biases are associated with deficiencies in the cloud optical properties, namely, cloud liquid water path and cloud effective radius specification. -from Authors"
"55411540900;","National satellite systems capabilities relevant to climate studies",1994,"10.1016/0273-1177(94)90345-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028333172&doi=10.1016%2f0273-1177%2894%2990345-X&partnerID=40&md5=b4c9e87b86032aa729b3dfeb6ea1e53d","During the 1990's a number of russian meteorological and environmental satellite missions is scheduled which will be of potential benefit to climate studies. On-board instruments to be flown on ""Meteor"", ""Goms"", ""Resurs"" and ""Okean"" series of satellites operated by the Committee for Hydrometeorology and Environment Monitoring of the Russian Federation (Roskomgidromet) will provide observations and soundings relevant to the radiation budget and cloud studies, ocean-atmosphere interaction and middle atmosphere monitoring. The current and planned sensor capabilities for carrying out some of these observational programmes are presented in this paper. An outline of ""Meteor-3/TOMS"" and ""Scarab"" projects is given as an example of mutually fruitful international cooperation to provide a valuable input in acquisition of data related to Global Change and Climate studies. © 1993."
"6505568138;24511929800;6506101358;","Sensitivity of the LMD general circulation model to greenhouse forcing associated with two different cloud water parameterizations",1994,"10.1175/1520-0442(1994)007<1827:sotlgc>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028599228&doi=10.1175%2f1520-0442%281994%29007%3c1827%3asotlgc%3e2.0.co%3b2&partnerID=40&md5=18d89d88674d142bdf80c5fabc0c0e7c","The atmospheric general circulation model is coupled to a slab ocean model and is used to investigate the climatic impact of a CO2 doubling. Two versions of the model are used with two different representations of the cloud-radiation interaction. The annual and global mean of the surface warming is similar in the two experiments in spite of regional differences. The results show that, in the second model version, the cloud feedback decreases significantly, especially at high latitudes, due to an increase of low-level clouds in the 2 × CO2 simulation. The modification of the cloud scheme influences also the water vapor variation and the associated feedback is reduced, in particular, over the subtropical regions. -from Authors"
"57208765879;7003830856;","Determining the susceptibility of cloud albedo to changes in droplet concentration with the Advanced Very High Resolution Radiometer",1994,"10.1175/1520-0450(1994)033<0334:dtsoca>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028571917&doi=10.1175%2f1520-0450%281994%29033%3c0334%3adtsoca%3e2.0.co%3b2&partnerID=40&md5=7888e1f2ee7026c1faf0e9bdddde1679","A calculation of cloud susceptibility, defined in this work as the increase in albedo resulting from the addition of one cloud droplet per cubic centimeter (as cloud liquid water content remains constant), is made through the satellite remote sensing of cloud droplet radius and optical thickness. The remote technique uses spectral channels of the AVHRR instrument on board NOAA polar-orbiting satellites. Radiative transfer calculations of reflectance and effective surface and cloud emissivities are made for applicable sun and satellite viewing angles, including azimuth, at various radii and optical thicknesses for each AVHRR channel. Emission in channel 3 (at 3.75 μm) is removed to give the reflected solar component. These calculations are used to infer the radius and optical thickness that best match the satellite measurements. The retrieved range of susceptibilities for all marine stratus clouds studied varied by about two orders of magnitude. This variation implies that climate studies that include possible marine stratus albedo modification from anthropogenic CCN are incomplete without accounting for existing susceptibilities. -from Authors"
"6603896143;","Applications of spatial analysis techniques for assessing the contribution of cloud seeding to rainfall in Israel",1994,"10.1080/02723646.1994.10642536","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84883598456&doi=10.1080%2f02723646.1994.10642536&partnerID=40&md5=4b4bf5dc11fda80e49541c78e668aee7","The paper summarizes two decades of fitting existing techniques and developing new spatial methods in order to aid the cloud seeders in proving or disproving the value of deliberate rainfall augmentation in Israel. While the spatial regression and the distance correlation matrix (DISTCORMAT) techniques served to distinguish between deliberate rainfall enhancement and inadvertent urban climate modification, the composite correlation map revealed an increase of rainfall duration and an extension of the rainfall target area. Hydrological parameters were utilized to assess the effect of cloud seeding on water resources. Indirectly, the hydrological evidence supported the positive effect of the cloud seeding. Those findings also suggest that cloud seeding augments the rainfall intensity, but interpretation of the composite correlation map does not support this notion. © 1994 Taylor & Francis Group, LLC."
"7403079681;7403590574;7403309879;","Remote sensing of cloud optical depth with AVHRR and ground-based observation",1994,"10.1016/0273-1177(94)90353-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028333173&doi=10.1016%2f0273-1177%2894%2990353-0&partnerID=40&md5=019427589f95a877ae4aed92d6cd8ce1","The Cloud is one of the most active factors in the physical climate system which may response to global changes of other systems and factors of the global earth system in very complicated manners and rather broad spatial and temporal scales. Therefore, cloud parameters are important targets in satellite and surface-based remote sensing. Presently, quantitative remote sensing of cloud parameters is still at the primary stage because of its complexity in phase, particle size distribution, adsorption and inhomogeneous distribution and rapid variation. In this paper, the comparison of combined observation of cloudy sky (both from NOAA satellite and from ground-based radiation and lidar observation) with radiative transfer model calculations are presented. The differences between observation and model calculation are discussed to illustrate the further steps necessary for reasonable results of cloud parameters. © 1993."
"7005516084;","Earth radiation balance and climate: Why the moon is the wrong place to observe the Earth",1994,"10.1016/0273-1177(94)90032-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-27644453328&doi=10.1016%2f0273-1177%2894%2990032-9&partnerID=40&md5=89ead06ff9dee8ac77b352c60b590052","Increasing ""greenhouse"" gases in the Earth's atmosphere will perturb the Earth's radiation balance, forcing climate change over coming decades. Climate sensitivity depends critically on cloud-radiation feedback: its evaluation requires continual observation of changing patterns of Earth radiation balance and cloud cover. The Moon is the wrong place for such observations, with many disadvantages compared to an observation system combining platforms in low polar, intermediate-inclination and geostationary orbits. From the Moon, active observations are infeasible; thermal infrared observations require very large instruments to reach spatial resolutions obtained at much lower cost from geostationary or lower orbits. The Earth's polar zones are never well observed from the Moon; other zones are invisible more than half the time. The monthly illumination cycleleads to further bias in radiation budget determinations. The Earth will be a pretty sight from the Earth-side of the Moon, but serious Earth observations will be made elsewhere. © 1994."
"7004462010;","Priorities in international collaboration to solve global environmental problems",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028680749&partnerID=40&md5=117d2790eed765123d94504e63ade0cb","The paper is mainly concerned with the problem of global climate changes and the optimisation of the Global Climate Observation System. In addition the following are substantiated: 1) the inadequacy of the ""greenhouse' stereotype for global climate warming, 2) the need to become aware of real ""climatic' properties (dynamics of the biosphere, atmosphere-ocean interaction, cloud cover and radiation, the colloidal nature of the atmosphere, etc.) Key problems of global ecodynamics, namely the Earth's thermal budget and the dynamics of the biosphere, are considered. Particular attention is paid to social and economic aspects of ecology. -from Author"
"6602835352;57203183278;","Measurements of noctilucent cloud heights: a bench mark for changes in the mesosphere",1994,"10.1016/0021-9169(94)90194-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028193523&doi=10.1016%2f0021-9169%2894%2990194-5&partnerID=40&md5=3fd03cc7736827918ffa933e93d235b7","Recent studies of noctilucent clouds indicate a secular increase in their frequency of occurrence which may be associated with changes either in the water vapour concentration or in the mean temperature of the mesopause. Noctilucent clouds are expected to be seen very close to the level where the relative humidity is 100% and changes in temperature of the mesosphere or in its water vapour content might be expected to alter the height at which the clouds occur. Comparison of our height measurements with those obtained over the past 100 yr shows that the suggested changes since 1885 in temperature (a decrease of approximately 7°C) and water vapour mixing ratio (an increase of approximately 1.7 ppmv) have not been sufficient to affect the height of the clouds by an observable amount. Future height measurements of noctilucent clouds may provide a practical indicator of changes taking place in the mesosphere which could be associated with global-scale alterations of the lower atmosphere. © 1993."
"7409902158;7409868847;7409634656;","A model of a coupled sea-atmosphere-cloud climate system",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028591547&partnerID=40&md5=c1c72f712031edd271987941428e7c18","Qualitative analysis shows that the system exists at least in five possible equilibrium states, and not four as traditionally considered. When the feedback of clouds is not considered, the SST will be raised by 0.96 K and 0.97 K respectively as the concentration of CO2 rises from 280 ppm and 330 ppm to 560 ppm and 660 ppm. When the feedback is included, the SST rises only about 0.51 K under the same conditions. Hence the greenhouse effect of CO2 is lessened to a certain extent. -after Journal summary"
[No author id available],"CEPEX Integrated Data System",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041146600&partnerID=40&md5=d4292a75d247d588b90125b32ec727e1","CIDS is the CEPEX Integrated Data System developed by the Center for Clouds, Chemistry and Climate (C4). It is a unique system that provides easy and uniform access to all the observations from the Central Equatorial Pacific Experiment (CEPEX) conducted in March and April, 1993. CEPEX was designed to address two primary scientific issues: (i) why are maximum SSTs in the tropical oceans so close to the 300K threshold for deep convection? and (ii), what are the restoring forces that limit SST and deep convection? Because the tropical climate is a coupled nonlocal system, investigation of these issues often requires a synthesis of a wide variety of in situ and satellite measurements. CIDS is designed to facilitate multidisciplinary research by providing a common interface to complex and heterogeneous data sets. It distinguishes itself from other Data Base Management Systems (DBMS) in that it facilitates automatic collocation and merging of measurements from any set of measuring platforms. One of the main objectives for CIDS is validation of the physics in General Circulation Models (GCMs). CIDS provides a simple mechanism for testing simulations of the tropical climate system against CEPEX data. Data sets in CIDS include: radiation; state parameters; water vapour; evaporative fluxes; microphysics; cloud properties; ozone; dynamical and thermodynamical fields; navigation. Questions regarding CIDS access and usage and applicability to your data sets may be directed to E.R. Boer: Center for Clouds Chemistry and Climate (C4) SIO/UCSD, 9500 Gilman Drive, M/C 0239 La Jolla, CA 92093-0239; phone (619) 534-6468 fax (619) 534-4922; or email: cids@borneo/ucsd.edu -from Publisher"
"7409821029;7003353805;","Retrieval of cloud liquid water using the special sensor microwave imager (SSM/I)",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028585663&partnerID=40&md5=6f613606380b34e98191c20d2f87d5e4","Three separate algorithms, each accurate for different ranges of liquid water, are combined to measure a large dynamic range of cloud liquid water path up to 3.0 mm. The major improvements of our present algorithm over many other previous studies are (1) the algorithm detects the liquid water in optically thin stratus and low-level clouds very well; (2) the algorithm measures the liquid water in highly convective clouds; (3) the algorithm can be applied to any climate regime because some of the coefficients (a1 and a2) are derived using a comprehensive training SSM/I data set obtained from various clear sky conditions; and (4) the liquid water derived using the present algorithm agree with that derived using the ground-based microwave radiometer measurements very well. -from Authors"
"7003591311;7006384616;","Feasibility of using multiwavelength lidar measurements to measure cloud condensation nuclei",1994,"10.1175/1520-0426(1994)011<1543:FOUMLM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028575160&doi=10.1175%2f1520-0426%281994%29011%3c1543%3aFOUMLM%3e2.0.CO%3b2&partnerID=40&md5=41c0f8d67334b9dfe3442b8cf5120aba","The proposed technique utilizes the fact that hygroscopic particles undergo a size increase and refractive-index change with increasing relative humidity and that different wavelengths respond to these changes in different ways. the lidar wavelengths considered are 0.289, 0.355, 0.532, 0.694, 1.064, and 2.02μm and the 9-11.5μm range. A judicious choice of lidar wavelengths can provide a differential backscatter, sufficient to provide information on the size and percentage number concentration of the hygroscopic aerosol and, consequently, cloud condensation nuclei concentration. The potential benefits of distinguishing hygroscopic particle concentration from nonhygroscopic particle concentration are great since remote measurement can provide good temporal and spatial coverage of these properties and valuable information for climate monitoring. -from Authors"
"7005814217;7003684963;7005513582;7006705919;7402435469;","Climate statistics from the National Center for Atmospheric Research community climate model CCM2",1994,"10.1029/94jd01570","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028554782&doi=10.1029%2f94jd01570&partnerID=40&md5=3a7773a5339dc68ef6dd6b26bc4bc823","The tropospheric thermodynamic cold and dry bias that has historically plagued the CCM is largely eliminated. The problem of a cold polar tropopause, although slightly improved, continues to be a major weakness of the simulation. Another more serious deficiency in the simulation is a warm bias in the northern hemisphere summer circulation, which affects the lower tropospheric and surface climate, as well as the top-of-atmosphere radiation budget. A large component of the northern hemisphere summer warm bias and the shift in western Pacific deep convection are related to limitations in the CCM2 diagnosis of cloud optical properties. Unrealistic nonlinear interactions between moist convection and atmospheric boundary layer processes also play a role in tropical precipitation distribution deficiencies. -from Authors"
"7003851092;","Pea Bullok: a preliminary account of a 30 000 year record of vegetation amd climatic change from highland north Sumatra",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028592186&partnerID=40&md5=77a56764cef4f8cf140315317bce476c","The pollen record from one of the two cores is described. It includes two AMS dates which imply that the bottom of the 8m core goes back to about 30 ka. An important factor in vegetation change is oscillation in the level of the cloud belt alongside fluctuations in the monsoon circulation. -K.Clayton"
"57212781009;6701715507;23080010200;6602929454;7801604834;","Snow and cloud feedbacks modelled by an atmospheric general circulation model",1994,"10.1007/BF00208257","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028327935&doi=10.1007%2fBF00208257&partnerID=40&md5=a8de51f16ffbf2bc31b183d11e729de2","One of the most important parametrizations in general circulation models used for climate change experiments is that of the surface albedo. The results of an albedo feedback experiment carried out under the auspices of the US Department of Energy are presented. An analysis of long and short wave components of the model response shows that short wave response dominates changes in fixed to variable albedo experiments, but that long wave response dominates in clear to cloudy sky changes. Cloud distribution changes are also discussed and are related to changes in global sensitivity. At the surface, the heat balance change for perturbed sea surface temperatures is dominated by changes in latent heat flux and downward long wave radiation. If albedo is freed up however, the major contrast lies in the change in surface reflected short wave radiation, amplified by changes in downward short wave radiation caused by cloud amount changes. © 1994 Springer-Verlag."
"6701540733;7006184606;57206416522;","Radiative-convective model with an explicit hydrologic cycle 1. Formulation and sensitivity to model parameters",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028554159&partnerID=40&md5=0f79200d212cd56bd74f7b73279e2704","A hydrological cycle is explicitly included in a one-dimensional radiative-convective equilibrium model which is coupled to a ""swamp' surface and tested with various cumulus convection schemes. The essential difference between our model and other radiative-convective models is that in our model the moisture profile (but not cloudiness) is interactively computed by the cumulus convection scheme. This has a crucial influence on the computation of the radiative fluxes throughout the atmopshere and therefore on the model's sensitivities. Using the Emanuel scheme, we show that clouds with high precipitation efficiency produce cold and dry climates. Clouds with low precipitation efficiency lead to moist and warm climates. The cumulus convection schemes currently in use in GCMs bypass the microphysical processes by making arbitrary moistening assumptions. -Authors"
"7003935733;","The current status of operational satellite products for climate studies",1994,"10.1016/0273-1177(94)90347-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028325668&doi=10.1016%2f0273-1177%2894%2990347-6&partnerID=40&md5=ca8aeb68a4fb46509409b82ce4f0dbe5","The current status of climate products being obtained from the real-time processing of operational satellite observations at NOAA is reviewed. Current global operational products relevant to climate studies include: atmospheric temperature and water vapor profiles, winds, clouds, aerosols, ozone, sea surface temperature, vegetation index, snow cover and sea ice, planetary albedo, and outgoing longwave radiation. Current experimental operational products include sea surface wind speed, precipitable water, precipitation rate, show cover and sea ice cover from the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I), and surface and atmospheric longwave radiation fluxes from the TIROS Operational Vertical Sounder (TOVS) radiance observations. Racent results, accuracy estimates based on comparison with ground truth, and problems and possibilities for using operational satellite data for long-term global climate change studies are presented. © 1993."
"7005814217;","Parameterization of moist convection in the National Center for Atmospheric Research community climate model (CCM2)",1994,"10.1029/93JD03478","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028193574&doi=10.1029%2f93JD03478&partnerID=40&md5=c741b2b8882ee1600799259ce72bb77e","The NCAR community climate model (CCM) has historically made use of a moist adiabatic adjustment procedure for parameterizing the effects of moist convection. The most recent version of the NCAR CCM, CCM2, has abandoned this approach in favor of a stability-dependent mass-flux representation of moist convective processes. This scheme physically constrains the process of moist convection with the use of a simple bulk cloud model, which provides a basis for estimating convective-scale transports of heat, moisture, and other atmospheric constituents as well as the diabatic heating associated with condensation and the fallout of precipitation. This paper presents the formalism associated with this simple mass-flux approach. -from Author"
"35446498700;6506976332;","The role of clouds in the enhancement of cloud condensation nuclei concentrations",1994,"10.1016/0169-8095(94)90034-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028317453&doi=10.1016%2f0169-8095%2894%2990034-5&partnerID=40&md5=25de4002147f8ffeb801601337f59930","Three exist three possible mechanisms for the enhancement of cloud condensation nuclei (CCN) in the vicinity of and within clouds. Firstly, when clouds form due to mixing air masses, real-time CCN measurements show that CCN concentrations could register an increase around such clouds due to differences in the aerosol content of the two air masses (the mechanism being the transport of new CCN to the measurement site). Secondly, due to sulfate production within clouds themselves, the CCN concentration in the air mass processed by such clouds could be elevated due to a shift in the size distribution and chemical composition of the existing aerosol particles. Thirdly, new aerosol particles could be formed by the process of homogeneous, heteromolecular nucleation in the vicinity of and within clouds resulting from a modification of the supersaturation field. The third mechanism is capable of enhancing simultaneously both condensation nuclei (CN) and CCN concentrations. By analyzing the existing field measurements, examples demonstrating the enhancement in CCN concentration within clouds, close to the cloud top, and in clear but moist air above the cloud tops are provided. It is pointed out that for CCN to play an effective role in climate-regulation (i.e. counteracting the greenhouse warming due to CO2 etc.), their number concentrations should increase by as much as a factor of four which would cause an increase in the global albedo by ≈ 1.7%. Current evidence shows that such a CCN enhancement may be possible locally but is not observable in general. Although anthropogenically influenced arctic stratus clouds were observed to produce significant CCN enhancement, no such effect was observed in antarctic stratus clouds. A model based on homogeneous, heteromolecular aerosol particle production was used to calculate particle production. Model results of sensitivity studies are presented that explain why the observations of this phenomenon so far have been so few. Enhanced actinic radiation flux, high relative humidity, abundance of gaseous sulfur, and long life span of clouds are found to be common features of observations that indicate CCN enhancement within clouds. Such clouds are very active photochemically. Sampling artifacts encountered in airborne observations could also occur and may explain partially or totally the observed CCN enhancement although this explanation is far from satisfactory and precludes the observed CCN enhancement in clear moist layers above the cloud tops. © 1994."
"7003597653;7202746102;6701481007;7004027742;57197997371;24282816200;6602504047;6505824944;","Global scale observation of the earth for climate studies",1994,"10.1016/0273-1177(94)90364-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028193906&doi=10.1016%2f0273-1177%2894%2990364-6&partnerID=40&md5=d5d4bf6312b8ccc584ff267841cce43f","Developed since 1983 at LMD, the 3I (Improved Initialization Inversion) physical retrieval algorithm has been recently extended to the processing of NOAA (TIROS-N Operational Vertical Sounder) observations at global scale. Starting from the version implemented at ECMWF in Reading, this global scheme has been recently improved and installed on a CRAY-2. One month of observations (Feb. 1989) of NOAA-10 and 11 has recently been processed, at a spatial resolution of 100 × 100 km2. A two years period should now be processed, in conjunction with the PathFinder and GEWEX-GVaP programmes. Results expected are: weekly to monthly averages of quantities like temperature structure, cloud parameters or the vertical distribution and total content of water vapor analysed in relationship to pertinent meteorological or other parameters, especially with respect to quantifying the fundamental characteristics and origines of water vapor variability. © 1993."
"55781067400;","Use of satellite-based sensing in land surface climatology",1994,"10.1177/030913339401800101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028322782&doi=10.1177%2f030913339401800101&partnerID=40&md5=9329ac52559a7924c59bd8e888b57ce5","Common types of satellite-derived measurements are reviewed with respect to how they are used to provide information on variables important to land surface climatology. The variables considered include solar radiation, surface albedo, surface temperature, outgoing longwave radiation, cloud cover, net radiation, soil moisture, latent and sensible heat flux, surface cover and leaf area index. A selection of land surface climate modelling schemes is identified and considered with a view to their practicality for use with satellite-derived data. Issues arising from the foregoing considerations include the absence from satellite data of some variables required by land surface climate models, the importance of extreme pixel values in model parameterization, the importance of matching spatial resolution in satellite data and climate model, and the need to have concurrent, independently observed, meteorological data in order to make full use of the satellite data. © 1994, Sage Publications. All rights reserved."
"25941200000;7409080503;27267529400;","Radiative characteristics of the Canadian Climate Centre second- generation general circulation model",1994,"10.1175/1520-0442(1994)007<1070:RCOTCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028607840&doi=10.1175%2f1520-0442%281994%29007%3c1070%3aRCOTCC%3e2.0.CO%3b2&partnerID=40&md5=1b5641192d278e8d3056a2bb5d0cb998","The GCM data were obtained from the Atmospheric Model Intercomparison Project (AMIP) simulation. Data corresponding to the period January 1985 through December 1988 were examined since this period of the AMIP simulation overlaps with the Earth Radiation Budget Experiment (ERBE) and the International Satellite Cloud Climatology Project (ISCCP) datasets. Ocean albedos are too high in the Tropics and too low in the polar regions relative to surface observations and theoretical estimates. Compared to a satellite-derived dataset, however, they are slightly underestimated. Throughout much of the Sahara and Saudi Deserts surface albedos are too low, while for much of Western Australia they are too high. Like many GCMs, the CCC model has too little atmospheric H2O vapor. This results in too much outgoing longwave radiation from clear skies, especially in the Tropics. Neglect of all trace gases except for CO2 and weak H2O vapor absorption exacerbate this bias. Cloud radiative forcing CRF from the GCM was compared to CRF obtained from ERBE data. Globally averaged, net CRF is in excellent accord with observations but shorwave and longwave CRFs are too strong. Zonal averages, however, reveal biases in which clouds act to cool the Tropics too much and cool the high latitudes too little during summer, yet they warm polar regions too much during winter. -Authors"
"6701791841;6603318887;","Global radiation climate change at seven sites remote from surface sources of pollution",1994,"10.1007/BF01094010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028180533&doi=10.1007%2fBF01094010&partnerID=40&md5=193212b9627f7740303d0430271c1eb9","Seven series of global radiation measurements, totaling 190 stationyears, were analyzed from sites covering the world-wide range of insolation regimes. All were remote from any local surface sources of atmospheric pollution. Global radiation decreased linearly with year of measurement at all sites and at six of them the decreases were statistically significant, averaging annually 17.67 MJ m-2 yr-1 (0.56 W m-2). Observations of daytime cloud cover made at five of the sites showed no large or significant changes over the same periods. There was some indication that the rates of decline in global radiation were larger at sites and during years with greater-than-average cloud cover. The results confirm an earlier finding of a large-scale decline in insolation, derived from an analysis of data from the World Radiation Network and show that this cannot only be attributed to local sources of pollution. Temporal variations in the rate of insolation decline were small; spatial variations were large and unexplained. © 1994 Kluwer Academic Publishers."
"6506801472;6504651690;56292239600;","Solar radiation and surface temperature in Shanghai City and their relation to urban heat island intensity",1994,"10.1016/1352-2310(94)90478-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028552505&doi=10.1016%2f1352-2310%2894%2990478-2&partnerID=40&md5=0dfe5aa2930de460736b1bbd0e0bd818","To clarify the effect of solar radiation on the intensity of the Shanghai urban heat island, we surveyed 154 daily radiation data at rural Xingzhuang and urban Longhua. A regression equation shows that direct solar radiation has a positive effect on urban heat island intensity, but that the wind velocity and cloudiness have a negative effect. Surface temperature records provided by satellites and the simultaneous observational data of direct solar radiation, atmospheric temperature, cloud amount and wind velocity from meteorological stations inside and outside of Shanghai City are used to analyse several typical cases of both surface and 1.5 m air temperature urban heat islands in different seasons. © 1994."
"7003398947;","Bounded cascade clouds:albedo and effective thickness",1994,"10.5194/npg-1-156-1994","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984403649&doi=10.5194%2fnpg-1-156-1994&partnerID=40&md5=5ee874ab24d52781b9acc5bcdf7dd760","If climate models produced clouds having liquid water amounts close to those observed, they would compute a mean albedo that is often much too large, due to the treatment of clouds as plane-parallel. An approximate lower-bound for this “plane-parallel albedo bias” may be obtained from a fractal model having a range of optical thicknesses similar to those observed in marine stratocumulus, since they are more nearly plane- parallel than most other cloud types. We review and extend results from a model which produces a distribution of liquid water path having a lognormal-like probability density and a power-law wavenumber spectrum, with parameters determined by stratocumulus observations. As the spectral exponent approaches -1, the simulated cloud approaches a well-known multifractal, referred to as the “singular model”, but when the exponent is -5/3, similar to what is observed, the cloud exhibits qualitatively different scaling properties, the so- called “bounded model”. The mean albedo for bounded cascade clouds is a function of a fractal parameter, 0 < f < 1, as well as the usual plane-parallel parameters such as single scattering albedo, asymmetry, solar zenith angle, and mean vertical optical thickness. A simple expression is derived to determine f from the variance of the logarithm of the vertically-integrated liquid water. The albedo is shown to be approximated well by the plane-parallel albedo of a cloud having an “effective” vertical optical thickness, smaller than the mean thickness by a factor χ(f), which is given as an analytic function of f. California stratocumulus have a mean fractal parameter f ≈ 0.5, relative albedo bias of 15%, and an effective thickness 30% smaller than the mean thickness (χ ≈ 0.7). For typical observed values of mean liquid water and f, the effective thickness approximation gives a plane-parallel albedo within 3% of the mean albedo. © European Geophysical Society 1994."
"7007026915;7005050002;7401509344;7801603125;6701485387;7006005654;","Climatic‐scale vegetation—cloud interactions during drought using satellite data",1994,"10.1002/joc.3370140602","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028562825&doi=10.1002%2fjoc.3370140602&partnerID=40&md5=0b774a0cf2a277be2cc3fa91dcaf4424","Land‐surface‐atmosphere interactions for the 1988 summer drought in the Mid‐west USA are studied at climatic scales (104 km2; &gt;5 days) using polar orbiter satellite radiance information on vegetation activity and cloud conditions. The emphasis is on documenting the occurrences of ‘organized’ land‐cover types and cumulus convection, and evaluating their mutual associations. For purpose of comparison, similar analyses are performed for the more moisture sufficient (non‐drought) summer of 1987. The satellite retrievals and analysis methods are calibrated using station meteorological data on precipitation and surface moisture, and also land‐cover maps. In early summer (June) 1988, Mid‐west USA land surfaces were generally highly stressed (high shortwave reflectance, high surface temperatures), particularly for the Corn Belt. Moreover, the spatial variation of the land‐cover signal was greater than in June 1987, and also when compared with later that summer (August 1988). Statistical analysis suggests a significant role for the land surface conditions of early summer in the spatial patterns of deep convection over the remainder of the season. This involves generally higher (lower) frequencies of convective cloud days for surfaces having a high relative density of forest vegetation (crops). Because broadly similar results are obtained for the summer of 1987, the possibility exists that the vegetation‐convective‐cloud interaction may be a feature of Mid‐west USA summer climate. The diurnal dependence of cloud‐forming processes for agricultural and natural vegetation regions is assessed using GOES cloud imagery at high temporal resolution for a “typical” convective day in early summer 1988. Associations with station radiosonde data support the hypothesis that spatial differences in land cover influence the generation and timing of convective cloudiness for the Mid‐west region. Copyright © 1994 John Wiley &amp; Sons, Ltd"
"7102018821;7401622015;","Light scattering by nonspherical particles: Remote sensing and climatic implications",1994,"10.1016/0169-8095(94)90004-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028192951&doi=10.1016%2f0169-8095%2894%2990004-3&partnerID=40&md5=39d6ecd259771be71e33a06f5e55d15b","Calculations of the scattering and adsorption properties of ice crystals and aerosols, which are usually nonspherical, require specific methodologies. There is no unique theoretical solution for the scattering by nonspherical particles. Practically, all the numerical solutions for the scattering of nonspherical particles, including the exact wave equation approach, integral equation method, and discrete-dipole approximation, are applicable only to size parameters less than about 20. Thus, these methods are useful for the study of radiation problems involving nonspherical aerosols and small ice crystals in the thermal infrared wavelengths. The geometric optics approximation has been used to evaluate the scattering, absorption and polarization properties of hexagonal ice crystals whose sizes are much larger than the incident wavelength. This approximation is generally valid for hexagonal ice crystals with size parameters larger than about 30. From existing laboratory data and theoretical results, we illustrate that nonspherical particles absorb less and have a smaller asymmetry factor than the equal-projected area/volume spherical counterparts. In particular, we show that hexagonal ice crystals exhibit numerous halo and arc features that cannot be obtained from spherical particles; and that ice crystals scatter more light in the 60° to 140° scattering angle regions than the spherical counterparts. Satellite remote sensing of the optical depth and height of cirrus clouds using visible and IR channels must use appropriate phase functions for ice crystals. Use of an equivalent sphere model would lead to a significant overestimation and underestimation of the cirrus optical depth and height, respectively. Interpretation of the measurements for polarization reflected from sunlight involving cirrus clouds cannot be made without an appropriate ice crystal model. Large deviations exist for the polarization patterns between spheres and hexagonal ice crystals. Interpretation of lidar backscattering and depolarization signals must also utilize the scattering characteristics of hexagonal ice crystals. Equivalent spherical models substantially underestimate the broadband solar albedos of ice crystal clouds because of stronger forward scattering and larger absorption by spherical particles than hexagonal ice crystals. We illustrate that the net cloud radiative forcing at the top of the atmosphere involving most cirrus clouds is positive, implying that the IR greenhouse effect outweighs the solar albedo effect. If the radiative properties of equivalent spheres are used, a significant increase in cloud radiative forcing occurs. Using a one-dimensional cloud and climate model, we further demonstrate that there is sufficient model sensitivity, in terms of temperature increase, to the use of ice crystal models in radiation calculations. © 1994."
"6602256060;","Acoustic sounding of lifted inversions",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028680657&partnerID=40&md5=f970d1486afcee937b93a67df2f82e1d","Frequency, distribution, and mean heights of lifted temperature inversions in the lower 800-m have been obtained from data derived from acoustic soundings made at Moscow in 1988-1992. Their highest frequency is noted late in the fall and early in the winter, which is related to a combined effect of two factors: air subsidence in an anticyclone in the cold season and frequent above-cloud inversions in the fall. -from Journal summary"
"57212781009;6701715507;6701652286;","Sensitivity of the Australian surface hydrology and energy budgets to a doubling of CO2",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028668492&partnerID=40&md5=76a5e0bf36a37eb7139319b05b120125","In the modelled doubled CO2 climate, the BMRC GCM finds a strong increase in soil moisture in northern Australia in summer, due to a large increase in precipitation. Both models find a decrease in soil moisture in southern Australia in winter. Changes in the surface heat budget involve a general increase in downwards long wave radiation except for southern Australia in autumn. The model response generally produces a close ""pairing' of long and short wave radiation changes, caused primarily by clouds and resulting in net radiative changes at the surface close to zero. This forces a similar pairing of latent and sensible heat changes to occur also. -from Authors"
"6701849060;","Sea ice altimeter processing scheme at the eodc",1994,"10.1080/01431169408954124","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028184168&doi=10.1080%2f01431169408954124&partnerID=40&md5=09c0da13029f78bd9e9d91ee965852ef","Sea ice presents a serious impediment to both shipping and off-shore operations in the polar regions. Since sea ice conditions can change within a matter of hours, near real time monitoring is required. Airborne data are available in some areas, but collection is expensive and coverage limited. Satellite images can provide wider coverage, but cloud cover, darkness and the need for rapid processing and dissemination can limit their use. Information on sea ice cover over longer periods is needed for global climate monitoring. Microwave sensors provide the most practical means of monitoring global sea ice covcr since they can operate both at night and day and observe through clouds. Previous studies have concentrated on the use of passive microwave data. Here we discuss the routine monitoring of sea ice using the ERS-1 radar altimeter. The low data rate and somewhat simple nature of the data, lend themselves to the mapping of global sea ice cover and to operational applications. We review the processing adopted at the U.K. EODC. © 1994 Taylor & Francis Group, LLC."
"56269065000;","Normalization of multi-annual global AVHRR reflectance data over land surfaces to common sun-target-sensor geometry",1994,"10.1016/0273-1177(94)90360-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028193458&doi=10.1016%2f0273-1177%2894%2990360-3&partnerID=40&md5=de5c61ba732562a828d6628deeed115f","Time series of the NOAA Global Vegetation Index data set for the period 1985-1991 were analyzed. The Advanced Very High Resolution Radiometer (AVHRR) cloud-free reflectance data were recalibrated to remove the trends due to the sensor sensitivity change and then normalized to nadir at 45° solar zenith angle using anisotropic top-of-the-atmosphere reflectance models. The results of such a normalization procedure show a substantial reduction in week-to-week variability of the spatial means. The present results demonstrate that relatively stable time series can be obtained by applying empirically derived regional anisotropic models. Thus, the improved data set is potentially more useful for monitoring biosphere-hydrology interactions and for use in numerical climate models. © 1993."
"57193132723;6507993848;7403318365;","Climatic implications of the seasonal variation of upper troposphere water vapor",1994,"10.1029/94GL02658","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028668537&doi=10.1029%2f94GL02658&partnerID=40&md5=d199f185cfce848a2d5f9f2668568542","Satellite observations indicate that the humidity of the upper troposphere is higher in summer than in winter. We use general circulation model (GCM) simulations to explore the processes that maintain upper troposphere water vapor and determine its seasonal cycle. In the subtropics, drying by Hadley cell subsidence and stratiform condensation is offset primarily by moistening by eddies, with moist convection playing a minor role. Elsewhere, both mean meridional circulation and eddies moisten the upper troposphere and are balanced primarily by stratiform condensation drying. The effect of the seasonal shift of the Hadley cell is limited to latitudes equatorward of 30°. At higher latitudes where the largest observed summer moistening occurs, eddy moisture fluxes are primarily responsible despite the eddies being weaker in summer than winter. The same mechanism causes upper level humidity to increase in GCM climate warming simulations. The observed seasonal variation may thus be a good proxy for decadal climate change. This suggests that upper troposphere water vapor feedback is positive at all latitudes, consistent with GCM predictions. Copyright 1994 by the American Geophysical Union."
"7003977187;7005567949;57203078473;7006247122;","The importance of atmospheric chemistry in the calculation of radiative forcing on the climate system",1994,"10.1029/93JD02987","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028192919&doi=10.1029%2f93JD02987&partnerID=40&md5=8d3f60dbf6683619e2b64e40d4f62baf","An interactive two-dimensional model of the troposphere, stratosphere, and mesosphere, in which dynamics, radiation, and chemistry are treated interactively, is used. The perturbations in the atmospheric oxidation capacity due to anthropogenic emissions of source gases are found to be significant. In the troposphere, an ozone increase of 80-120% at northern midlatitudes and a global decrease of 10-20% in the OH concentration since the preindustrial period are calculated. In the polar lower stratosphere of the southern hemisphere, an ozone depletion since preindustrial times reaching more than 60% during spring is calculated as a result of rapid catalytical destruction of ozone by chlorine radicals in the presence of polar stratospheric clouds. Particular attention is given to the induced changes in radiative forcing. On a global average basis, the greenhouse effect of tropospheric ozone represents approximately 17% of the total radiative perturbation. This forcing is characterized by a strong latitudinal dependence, peaking at midlatitudes in the northern hemisphere. The importance of indirect climate forcings by stratospheric ozone (including local cooling of the stratosphere) is confirmed. -from Authors"
"7003904922;7004265166;57199248260;","Stratospheric volcanic aerosols and changes in air-earth current density at solar wind magnetic sector boundaries as conditions for the Wilcox tropospheric vorticity effect",1994,"10.1029/94jd01207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028561437&doi=10.1029%2f94jd01207&partnerID=40&md5=2d897faf49d38607d83a1d23915d27f6","A correlation between tropospheric dynamics and solar wind magnetic fields that disappeared in the early 1970s reappeared with a new injection of volcanic aerosols into the stratosphere. A similar pattern of correlation has been found for changes in current density in the global electric circuit and for changes in relativistic electron precipitation. Several other weather and climate variations have been found to correlate with changes in air-earth current density due to solar wind modulation of the global electric circuit. The accumulation of electrostatic charge on supercooled droplets at cloud tops responds to air-earth current density changes. A mechanism linking the effects of charge accumulation to changes in ice nucleation, precipitation efficiency, latent heat retention and perturbations in atmospheric dynamics is thus as an explanation for this and other solar wind - atmospheric electricity - weather and climate conditions. -Authors"
"16520043600;","The Mediterranean Sea as a climate test basin",1994,"10.1007/978-94-011-0870-6_10","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028194312&doi=10.1007%2f978-94-011-0870-6_10&partnerID=40&md5=4d09948f0d986a677ac534c9252d6e3b","The semi-enclosed nature of the Mediterranean Sea makes it a useful basin for testing formulae for components of the heat flux into the sea. Various analyses have given higher values for the total heat input than implied by the exchange through the Strait of Gibraltar. This imbalance has led to proposed adjustments of one, or all three, of the insolation (partly to allow for the effects of aerosols), the longwave back radiation and the latent heat loss. Adjustment of the latter is constrained, however, by the water budget. An analysis of variability shows that real trends are hard to establish due to changes in observing practice, although there has been a 10% increase in reported cloud cover from 1946 to 1988. The interannual variability in computed heat flux is probably incompatible with the heat content of the Mediterranean, suggesting that standard formulae are inadequate for a study of interannual changes. -from Author"
"6701886397;6505869499;7003577870;6506821742;55404397500;7006871761;","A complex for calculation of synoptic and climatic characteristics of wind waves",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028667304&partnerID=40&md5=e05721a2669328dbd617803276af3d06","A set of innovative hydrodynamic and probability models of wind and wind waves is described. The models of the atmospheric boundary layer and associated wind waves are consistent with each other, which made it possible to develop a coupled adaptive model of these two phenomena. It is seen in the model how wind and waves adjust to each other as they develop. Discussed are the processes in both the near-water layer and the entire atmospheric boundary layer taking into account the radiation phenomena in case of stratocumulus clouds. -Authors"
"55745955800;7005070958;7202206836;56134545200;","Approaches of comparison for clear-sky radiative fluxes from general circulation models with Earth radiation budget experiment data",1994,"10.1029/93JD03341","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028190430&doi=10.1029%2f93JD03341&partnerID=40&md5=eb94e2233d62e5f779f90592d1e3ba02","In order to compare the clear-sky greenhouse effect and cloud-radiative forcing from general circulation models with Earth Radiation Budget Experiments (ERBE) data, it is necessary to calculate the general circulation model (GCM) clear-sky radiative fluxes in a way consistent with ERBE. This study discusses problems associated with the available methods for clear-sky radiative flux computations in GCMs and proposes a new approach, which uses a statistical relationship between the grid cloud cover and the availability of ERBE clear-sky measurement, established from ERBE pixel data, to sample the model radiative fluxes. Calculations with version 2 of the NCAR Community Climate Model using observed SST show good agreement of clear-sky sampling from the proposed method with ERBE sampling. It is also shown that large improvements are achieved in the spatial variability of the model clear-sky radiative fluxes over ocean, with reference to ERBE, by using the new clear-sky sampling method. -Authors"
"26643041500;7005728145;","Particle formation due to SO2 oxidation and high relative humidity in the remote marine boundary layer",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028601050&partnerID=40&md5=f6dbe1b35bcb0845b18ae0856a20206a","Nucelation in the marine boundary layer affects the distribution of natural sulfur across the aerosol size spectrum and thus may contribute to marine cloud condensation nuclei (CCN) concentrations and climate forcing. We investigated how nucleation probability in remote marine areas develops under different conditions. Our study suggests that conditions favorable for particle formation correspond to transitions from moderate to high relative humidities. The highest nucleation probabilities were associated with transitions that (1) are relatively rapid, (2) occur near the local solar noon, and (3) are a result of the cooling of the air. -from Authors"
"56733172800;6604000335;7004479395;7103406595;6602112643;6701772402;6701607011;","The POLDER Mission: Instrument Characteristics and Scientific Objectives",1994,"10.1109/36.297978","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028426614&doi=10.1109%2f36.297978&partnerID=40&md5=3e32a9745d0272bc274d38907153ba2c","This paper introduces the new Polarization and Directionality of the Earth's Reflectances (POLDER) instrument. The spaceborne POLDER sensor, which is selected to fly aboard the Japanese ADEOS satellite scheduled for launch in early 1996, has nearly completed phase C of its development at the Centre National d'Etudes Spatiales, the French space agency. To prepare for the 1996 space mission, airborne prototypes are being tested and evaluated in the framework of various measurement campaigns. The POLDER sensor is designed to collect global observations of polarized and directional solar radiation reflected by the Earth-atmosphere system for climate and global change studies. Aboard the ADEOS platform, the POLDER mission will provide near-daily coverage of the Earth at 6 × 7 km2resolution. The POLDER system will offer unprecedented opportunities to observe biophysical parameters over the oceans and land surfaces. The sensor's unique features, when compared to current and planned spaceborne instruments, include its ability to: 1) measure polarized reflectance in the visible and near-in-frared spectral regions; 2) observe Earth target reflectance from 12 directions during a single satellite pass; and 3) operate in two dynamic modes in order to achieve both high signal to noise ratio and wide dynamic range. Six of POLDER's eight channels are optimized for observing atmospheric aerosols, clouds, ocean color, and land surfaces. The other two are centered on the H2O and O2absorption bands for retrieving atmospheric water vapor amount and cloud top altitude, respectively. POLDER data will be subject to the high calibration standards defined by the POLDER mission team, with absolute calibration accuracies of 2% for the shorter wavelength channels (λ < 565 nm) and 3% for the longer wavelengths. A 1% accuracy is the goal for the intercalibration between the spectral channels. The POLDER instrument aboard ADEOS will contribute significantly to climate-related research on aerosol cycling, cloud-radiation interactions, the Earth radiation budget, ocean primary productivity, and continental biosphere dynamics. Using POLDER capability to measure bidirectional reflectance and polarization distribution functions for estimating biophysical parameters, the POLDER mission's scientific objectives will be to: 1) map atmospheric aerosols, including their sources and © 1994 IEEE."
"7005123759;7201903057;35511604900;57194933853;35573513700;6603565405;7202208382;","A global 1° by 1° NDVI data set for climate studies. Part 2: The generation of global fields of terrestrial biophysical parameters from the NDVI",1994,"10.1080/01431169408954343","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028586459&doi=10.1080%2f01431169408954343&partnerID=40&md5=ce1077946e541eb56cf758b5ccef2ed1","A satellite-based 1“ by 1° normalized difference vegetation index (NDVI) data set has been processed to derive land surface parameters for general circulation models of the atmosphere (GCMs). Prior to calculation of the land surface parameters, corrections were applied to the source NDVI data set to account for (i) obvious anomalies in the data time-series, (ii) the effect of variations in soiar zenith angle, (iii) data dropouts in cold regions where a temperature threshold procedure designed to screen for clouds also eliminates cold land surface points, and (iv) persistent cloud cover in the tropics. An outline of the procedures for calculating land surface parameters from the corrected NDVI data set is given, and a brief description is provided of source material that was used in addition to the NDVI data. The data sets summarized in this paper should represent improvements over prescriptions currently used in land surface parameterizations in that the spatial and temporal dynamics of key land surface parameters, in particular of those related to vegetation, are obtained from direct measurements rather than indirectly inferred from survey-based land cover classifications. © 1994 Taylor & Francis Ltd."
"57025126800;35573513700;7201903057;","A global 1° by 1° NDVI data set for climate studies derived from the GIMMS continental NDVI data",1994,"10.1080/01431169408954342","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028594999&doi=10.1080%2f01431169408954342&partnerID=40&md5=762d4b570cdb4e9d64f8161c4872e521","A nine-year (1982-1990) global normalized difference vegetation index (NDVI) data set with a spatial resolution of 1° by 1° and a temporal resolution of one month was compiled for use in climate studies. This data set was derived from higher resolution (5-8 km) monthly continental NDVI data sets that have been processed and archived by the Global Inventory Monitoring and Modelling Studies (GIMMS) group at NASA/Goddard Space Flight Center. The continental GIMMS NDVI data sets were calculated from Global Area Coverage (GAC) data collected at daily intervals by the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA-7, -9 and -11 satellites. The global 1° by 1° NDVI data set was produced to calculate land surface parameters for use within general circulation model J of the atmosphere (GCM). In view of this quantitative application, an evaluation is given of the representation by the NDVI data of the spectral properties of vegetation at the landsurface. Errors are defined as deviations from measurements obtained under standard conditions, i.e., conditions at the-top-of-the-atmosphere with no clouds, clear atmosphere, near-nadir viewing angles, overhead Sun, and invariant soil background. The discussion includes an assessment of (1) the data collected and processed onboard the AVHRR; (2) processing of the AVHRR data into the continental GIMMS NDVI data sets; (3) resampling of the continental data sets to a 1° by 1° data set; and (4) propagation of inconsistencies and biases from (1), (2) and (3) into the 1° by 1° global NDVI data. Examples are shown of the temporal and spatial variations in spectral properties of vegetation contained in the 1° by 1° NDVI data, and these are compared with the dynamics of biophysical parameters derived from land cover classes that were used in previous climate studies. © 1994 Taylor & Francis Ltd."
"7101677832;55471597600;","Radiation energy budget studies using collocated AVHRR and ERBE observations",1994,"10.1175/1520-0450(1994)033<0370:REBSUC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028590363&doi=10.1175%2f1520-0450%281994%29033%3c0370%3aREBSUC%3e2.0.CO%3b2&partnerID=40&md5=36a81d387c58f025eee3a1bb2e555945","Changes in the energy balance of the top of the atmosphere are specified as a function of atmospheric and surface properties using observations from the Advanced Very High Resolution Radiometer (AVHRR) and the Earth Radiation Budget Experiment (ERBE) scanner. By collocating the observations from the two instruments, flown on NOAA-9, the authors take advantage of the remote-sensing capabilities of each instrument. The AVHRR spectra channels were selected based on regions that are strongly transparent to clear sky conditions and are therefore useful for characterizing both surface and cloud-top conditions. The ERBE instruments make broadband observations that are important for climate studies. The approach of collocating these observations in time and space is used to study the radiative energy budget of three geographic regions: oceanic, savanna, and desert. -Authors"
"6603688113;7006784145;7006592026;7005696178;","Diurnal temperature range for a doubled carbon dioxide concentration experiment: Analysis of possible physical mechanisms",1994,"10.1029/94GL00188","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028585242&doi=10.1029%2f94GL00188&partnerID=40&md5=fd50755c76cc6341416a077df49a60c5","An analysis of the results of a climate simulation for a doubling of atmospheric carbon dioxide concentration over the European region is reported. Physical mechanisms are sought which could explain possible changes in the diurnal temperature range (DTR) under conditions of increased atmospheric greenhouse gas content. We show that an important contribution to changes in DTR is given by soil moisture. In areas where soil moisture increases due to an increase in precipitation there is a positive change in latent heat flux and a decrease in sensible heat flux. As a result, in areas with increasing soil moisture, the increase in maximum daytime temperature will be smaller than that in minimum temperature, thereby causing a decrease in the DTR. The opposite occurs for areas which undergo soil drying. This process amplifies the effect of cloud changes on surface solar and infrared radiation and dominates the direct effect of downward infrared radiation associated with increasing greenhouse gas concentration. Because the soil water content is largely controlled by precipitation, our results are consistent with early observational findings of negative correlation between changes in precipitation and in diurnal temperature range. Copyright 1994 by the American Geophysical Union."
"7102886537;7006550762;57213162592;","Joint investigations of the middle Pliocene climate II: GISS GCM Northern Hemisphere results",1994,"10.1016/0921-8181(94)90016-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028163285&doi=10.1016%2f0921-8181%2894%2990016-7&partnerID=40&md5=a7f27c3443424537cb5e8dd4e24ea407","Marine microfaunal data and terrestrial pollen records indicate that the middle Pliocene (ca. 3 Ma) climate is the most recent period in geologic history with global temperatures nearly as warm as those predicted for the coming century. We used the GISS GCM to examine the Pliocene climate by specifying sea surface temperatures and vegetation distributions derived from U.S.G.S. data sets. The simulation resulted in 1.4°C warming, annually averaged over the Northern Hemisphere. Warming was greatest at high latitudes; consequently, the equator to pole temperature gradient decreased by 11.5°C. Surface air temperature increases were greatest in winter, as decreased snow and sea ice triggered a positive albedo feedback effect. At low latitudes, temperatures were mostly unchanged except for an anomalous 3°C cooling over eastern Africa. This anomaly is supported by palynological data and, in the simulation, was a response to the weakening of the Hadley circulation, which used subtropical clouds and evapotranspiration rates to increase. Evaporation and precipitation rates decreased over the oceans and the appearance of negative P-E anomalies might implications for the Pliocene thermohaline circulation. The hydrological cycle intensified over the continents, where annual evaporation, rainfall, and soil moisture all increased. However, simulated summer drought conditions are not corroborated by terrestrial records, pointing to deficiencies in either the model, the boundary conditions, or the terrestrial data interpretations. The Pliocene SST pattern implicates increased ocean heat flux as a component force behind the middle Pliocene warmth, since levels of CO2, large enough to cause the extreme high latitude temperatures, would generate more tropical warming than is indicated by floral and faunal records. Surface energy fluxes, calculated by the GCM, indicate that an increased meridional ocean heat flux of 32% could reproduce the data-derived SST distribution, despite weakened atmospheric transports. The decreased wind stress valuessuggest that any increase of ocean heat transports would probably have resulted from a strentthening of the thermohaline circulation. © 1994."
"7004121485;7003399430;","Recent activities in the european community for the creation and analysis of global AVHRR data sets",1994,"10.1080/01431169408954337","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028571671&doi=10.1080%2f01431169408954337&partnerID=40&md5=ac94330888cc49aad86e5a4dbd3cc59a","This paper describes recent activities at the Commission of the European Communities’ Joint Research Centre (CEC-JRC) concerning the design of an Advanced Very High Resolution Radiometer (AVHRR) database for global climate and environmental studies (global change). Much of this work has concentrated on pre-processing of long-term AVHRR Global Area Coverage (GAC) data sets, with particular emphasis placed on the continent of Africa. To date, these data have been used to produce the Normalized Difference Vegetation Index, channel 2 reflectance, channel 3 and 4 brightness temperatures, an approximate surface temperature and a cloud probability image on a daily basis from April 1983 to January 1990 for the whole African continent at a resolution of 5 km. The remaining data from the entire GAC time series (July 1981 to the present) will be processed by early 1994. These data will be made available to the international research community through the CEC and European Space Agency initiative, the Centre for Earth Observation. The data sets have already provided new information concerning inter-and intra-annual variations in vegetation fire dynamics for Africa and have been used to derive forest seasonality information through the JRC’s thematic projects’ TRopical Ecosystem and Environment observations by Satellite (TREES) and Fire In global Resource and Environmental monitoring (FIRE). © 1994 Taylor & Francis Ltd."
"57193470841;","Effect of viewing geometry on remotely sensed net radiation measurements for vegetated and non-vegetated surfaces",1994,"10.1080/02723646.1994.10642535","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2142698773&doi=10.1080%2f02723646.1994.10642535&partnerID=40&md5=520e8c32f6b06c670216b8ffeeb9e0bd","Increased use of remotely sensed data for estimation of land-surface climatological variables such as the radiation and energy balance has underscored the need to understand errors inherent in remote sensing systems. The effects of viewing geometry on the signal received at the sensor have been examined for a variety of surface types, but systematic study of how sensor viewing geometry may introduce error into remote measurements of surface climate parameters is lacking. In this paper, close-range remote sensing is used to assess error caused by viewing geometry in remote measurements of net radiation, an important surface climate variable. Estimates of net radiation were made by inserting remotely sensed values of albedo and surface temperature into the surface radiation budget equation. Two contrasting surfaces, one vegetated and one bare, were evaluated at seven view angles and five azimuth angles. The remote net radiation measurements for each combination of view and azimuth angle then were compared to reference measurements to assess error. Results indicate that, under cloud-free conditions, view angle can affect measurement accuracy substantially, and that off-nadir view angles ranging from 15° to 30° in the forward-scatter direction are optimal. The potential impact of these findings on studies of the spatial variation of the surface radiation budget from spaceborne remote sensing platforms is discussed. © 1994 Taylor & Francis Group, LLC."
"7201394533;7201600437;","Climatic variability within an equilibrium greenhouse simulation",1994,"10.1007/BF00208252","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028262519&doi=10.1007%2fBF00208252&partnerID=40&md5=0999c2f94685d6d47344020690c30e66","A simulation of the possible consequences of a doubling of the CO2 content of the atmosphere has been performed with a low resolution global climatic model. The model included the diurnal and seasonal cycles, computed sea ice amount and cloud cover, and used implied oceanic heat fluxes to represent transport processes in the oceans. A highly responsive 2-layer soil moisture formulation was also incorporated. Twenty year equilibrated simulations for control (1 × CO2) and greenhouse (2 × CO2) conditions were generated. The major emphasis of the analysis presented here is on the intra-annual and interannual variability of the greenhouse run with respect to the control run. This revealed considerable differences from the time-averaged results with occasions of marked positive and negative temperature deviations. Of particular interest were the periods of negative temperature departures compared to the control run which were identified, especially over the Northern Hemisphere continents. Temporal and spatial precipitation and soil moisture anomalies also occurred, some of which were related to the surface temperature changes. Substantial sea surface temperature anomalies were apparent in the greenhouse run, indicating that a source of climatic forcing existed in addition to that due to doubling of the CO2. Comparison of the intra-annual and interannual variability of the control run with that of the greenhouse run suggests that, in many situations, it will be difficult to identify a greenhouse signal against the intrinsic natural variability of the climatic system. © 1994 Springer-Verlag."
"7102403008;","Climate of the 21st century",1994,"10.1016/0168-1923(94)90088-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028562587&doi=10.1016%2f0168-1923%2894%2990088-4&partnerID=40&md5=b3d06854fdb1981f9774e6aac4094640","The outgoing long wave radiation to space is significantly reduced as a result of heat absorption by the so-called greenhouse gases, notably water vapour, carbon dioxide, methane, nitrous oxides and chlorofluorocarbons. The dominating ones are water vapour and carbon dioxide. The direct effect of the greenhouse gases is to increase the average temperature of the earth's surface by some 33°C, that is from -18°C to the present +15°C. Since the industrial revolution the combustion of fossil fuels and deforestation has led to an increase of 26% in carbon dioxide in the atmosphere. It is presently increasing by about 0.5% per year. Based on strict radiative forcing calculations, the total additional warming because of the increase in greenhouse gases, not including the effect of associated changes in water vapour, is equivalent to about 2.5 W m-2 and is estimated to increase to some 10 W m-2 at the end of the next century. The solar constant, by comparison, is equal to 341 W m-2 globally averaged. The effect on climate cannot satisfactorily be estimated on radiation balance calculation only but must incorporate the large scale atmospheric circulation and the important feedbacks with water vapour (positive feedback), clouds (both positive and negative feedbacks), surface albedo and the oceans. For that reason it is necessary to build comprehensive mathematical models of the coupled ocean/land atmosphere system and carry out numerical simulation experiments. Several such studies have been undertaken during the last few years both in Europe and the USA. Results from these experiments, and in particular from those carried out at the Max-Planck-Institut für Meteorologie in Hamburg, will be presented and discussed. Because of the enormous complexity of the problem, a number of simplified assumptions have been used and the results so far must be cautiously assessed. The overall global warming from these experiments is about 3°C with a difference of about 0.5°C between the experiments. There are large regional differences and the warming is generally larger over land than over sea. A particular problem is the temperature of the North Atlantic and also in the Antarctic waters where changes in the deep ocean circulation are significant. The strong coupling to the deep ocean circulation in the North Atlantic reduces the warming in this area and consequently moderates the effect on the European climate. Sea level is estimated to increase by around 15 cm because of thermal expansion of sea water; however, it appears likely that there may also be an increased accumulation of ice on Antarctica and probably Greenland which may at least partly compensate for this increase. Possible changes in the vegetation following a climate change have been estimated by evaluating the response of a biome model. This shows minor changes in the vegetation; over Europe and North America a small north-eastward movement of the vegetation zones. © 1994."
"7004010406;6507553080;","The influence of the Indian Ocean/Indonesian SST gradient on the Australian winter rainfall and circulation in an atmospheric GCM",1994,"10.1002/qj.49712051808","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028607753&doi=10.1002%2fqj.49712051808&partnerID=40&md5=87ffae64d19653efb08f138102123715","A number of atmospheric general circulation experiments have been conducted with the aim of studying the impact of an enhanced sea surface temperature (SST) gradient, between the Indonesian archipelago and the central Indian Ocean, on the Australian winter circulation and rainfall. Particular emphasis is on modelled synoptic events and the sensitivity of mean winter climate anomalies to changes in the strength of the anomalous SST gradient. It is shown that an atmospheric general circulation model, forced by an anomalous SST gradient to produce mean winter circulation and precipitation anomalies qualitatively similar to the observed, simulates quite realistic synoptic events over the Australian continent. In particular, the model simulates an increased frequency of major Australian north‐west cloud bands. These events are associated with a triad of tropical systems in the Bay of Bengal, the Cocos Islands and the Indonesian archipelago, strong cross‐equatorial flow into a region north‐west of Australia, and interactions with short‐wave mid‐latitude disturbances. The mean climate anomalies, over Australia, are shown to be largely independent of whether a fixed or evolving anomalous gradient is used, but very sensitive to the magnitude of the SST anomaly. This is seen in the greater variability of the results over Australia. It is also suggested that the presence and strength of the warm anomaly in the Indonesian region has a greater bearing on the results than the cold anomaly, in the Indian Ocean. Global tropospheric circulation and precipitation anomaly patterns, associated with an enhanced gradient, are also shown to be consistent with some observed patterns, and to be robust with respect to changes in the magnitude and distribution of the SST anomalies. This suggests that an enhanced SST gradient may also be associated with rainfall variability in a number of geographical locations. Copyright © 1994 Royal Meteorological Society"
"7004723203;7103366892;7003784598;","Reduction of the Gibbs oscillation in spectral model simulations",1994,"10.1175/1520-0442(1994)007<1169:ROTGOI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028554306&doi=10.1175%2f1520-0442%281994%29007%3c1169%3aROTGOI%3e2.0.CO%3b2&partnerID=40&md5=b85fa6427b80d4dd33dd23480bcb4acc","Spectral atmospheric general circulation models (GCMs) have been used for many years for the simulation and prediction of the atmospheric circulation, and their value has been widely recognized. One of their major drawbacks is the inability of the spectral spherical harmonics transform to represent discontinuous features, resulting in Gibbs oscillations. Two applications of a filter technique are presented. In the first application the method is applied to the orography field by filtering out sharp gradients or discontinuities. The numerical results with this method show some improvement in the cloud and precipitation fields, along with some improvement of the surface wind pattern, resulting in an overall better simulation. In the second application, a Gibbs reduction technique is applied to the condensation process. In this paper the moist-adiabatic adjustment scheme is used for the cumulus parameterization, in addition to large-scale condensation. Numerical results with this method to reduce Gibbs oscillations due to condensation show some improvement in the distribution of rainfall, and the procedure significantly reduces the need for negative filling of moisture. The negative moisture areas at high latitudes can be, to some extent, controlled by an empirical procedure, but the filter approach is not sophisticated enough to satisfactorily remove the complex Gibbs oscillations present in the condensation field. -from Authors"
[No author id available],"TOGA related satellite and in-situ data CD-ROM '85-'90",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041146322&partnerID=40&md5=64d9f419e8d1aab6831af76c05bfaf95","The six read-only memory CD-ROMs contain data sets collected as part of the Tropical Ocean and Global Atmosphere (TOGA) experiment and PC software to browse and extract the data. There are 15 data sets included in this first release of the package. These data sets are: ECMWF - many parameters from the Basic Surface data set, Basic Upper Air data set, and Supplementary data set contained on a 2.5 degree grid (5.0 degree grid for Upper Air); CAC - Monthly analyzed SST fields and climatology-mean monthly fields on a 2.0 degree grid; IFREMER - Temperature and salinity sub-surface measurements; UHAWAII - Sea Level data for the Pacific and Indian oceans; UKMO - Surface marine observations from Voluntary Observing Ships; PMEL - Air temperature, air pressure, ocean currents and temperatures from islands and moorings in the Pacific; FSU and ORSTOM - Monthly analyzed pseudo-stress fields and climatology over the Pacific, Indian, and Atlantic; MEDS and AOML - Air temperature and pressure, sea surface temperature, and surface wind speed from satellite-tracked drifting buoys; ISCCP - Monthly average cloud, surface, and atmospheric properties; GPCP - Precipitation data; NCAR - climatologies; LODYC - Results from an operational model of the tropical Atlantic; and GEOSAT - Sea surface height data. All data are in standard ASCII format, except for ECMWF and ISCCP data, which are in binary WMO FM 92-IX Ext GRIB format. A users guide is supplied with each CD-ROM. Application software to search and retrieve data files and to view the files in tabular and graphical formats is provided on an additional CD-ROM. Contact: PO-DAAC User Services Office, MS 300-320, Jet Propulsion Laboratory, Pasadena, CA 91109, USA, or Fax: (818) 393-2718, Internet: podaac@podaac.jpl.nasa.gov. -S.Digby"
"6603383859;6603250119;","Numerical modelling of the energy balance and the englacial temperature of the Greenland Ice Sheet. Calculations for the ETH-Camp location (West Greenland, 1155 m a.s.l.)",1994,"10.1016/0921-8181(94)90010-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028194008&doi=10.1016%2f0921-8181%2894%2990010-8&partnerID=40&md5=d3658363312cdfebfb4bb2c305530df1","In the present work, a numerical model that calculates the surface energy blance, mass balance and temperature in the uppermost 25 m of ice at a single location on a glacier is presented. The model is forced by five ""basic"" meteorological elements: air temperature and humidity, wind speed, cloud amount and precipitation. The model was developed for studies of the Greenland Ice Sheet. Parameterizations of the surface energy fluxes were optimised with data mainly from the ETH Camp, West Greenland (1155 m a.s.l.). The model was tested on data collected during the summer of 1990 in the ETH Camp. In this case measurements of the radiative fluxes could be used. A reasonable fit between measurements and calculations of mass balance and englacial temperature could be obtained. The energy balance of this summer is discussed. In a second application, the annual cycle of the energy and mass balance and the englacial temperature at the location of the ETH Camp was simulated. In this case long term average values of the input variables were estimated from measurements at other locations and the radiative fluxes were computed with the parameterizations. The effect of model uncertainties on the calculated mass balance and 10 m ice temperature is discussed. The energy balance and the relation between air and ice temperature are analysed. The uncertainty in the calculated ablation is so large (500-1000 mm w.e./yr) that the contribution of ablation on the Greenland Ice Sheet to sea-level rise cannot be calculated with sufficient accuracy (i.e. 60 mm w.e./yr) with this kind of model. However, the model should be appropriate for the determination of the sensitivity of ablation to climate change. It is predicted that at the ETH Camp the mass balance will decrease by 610 mm w.e./yr after a temperature increase of 1°C. © 1994."
"7006069664;7101629992;8849542400;6603108267;","Variability of the Indian summer monsoon in relation to oceanic heat budget over the Indian seas",1994,"10.1016/0377-0265(94)90023-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028667878&doi=10.1016%2f0377-0265%2894%2990023-X&partnerID=40&md5=b35af5592678a062edaca007d73e2964","The influence of the surface marine meteorological parameters and air-sea fluxes of heat and moisture over the Indian seas (Bay of Bengal, Arabian Sea and equatorial Indian Ocean) on the interannual variability of the Indian summer monsoon has been studied in detail. The data base for this study, which consists of mean monthly marine meteorological fields for a period of 30 years (1950-1979), forms a part of the Comprehensive Ocean Atmospheric Data Set (COADS) analysed on a regular 1° latitude/longitude resolution. Using the surface marine meteorological fields, different components of the oceanic heat budget were computed. The basic meteorological fields, as well as the components of the oceanic heat budget, over the Indian seas were examined for the contrasting years of the summer monsoon (large excess rainfall: flood monsoon and large deficient rainfall: drought monsoon). To ascertain which regions were statistically significant in terms of heat budget over the Indian seas, the difference fields between two extreme categories of monsoon were subjected to Student's t-test. The study revealed that in the month of May preceding a flood monsoon, there were stronger surface winds and more abundant cloud cover over most parts of the Arabian Sea compared with a corresponding period prior to a drought season over India. Thus, as a result of enhanced evaporation and reduction of incoming solar radiation during the pre-monsoon month of May, the difference fields of the oceanic heat budget between the extreme years (flood/drought) illustrate a statistically significant zone of heat loss over the entire equatorial Arabian Sea. The analysis during the month of May provides a useful qualitative indication of the subsequent mean monsoon activity over the Indian sub-continent. With the commencement of the monsoon (June-August) and its northeastward progress over the Arabian Sea, all the difference fields of oceanic heat budget maintain the same signatures as found during the pre-monsoon month of May. However, the magnitude of the differences shows an overall reduction, with a shift of statistically significant zones from the equatorial region to the northern and eastern sectors of the Arabian Sea. © 1994."
"6701598045;7101619106;7101966764;","Our sun. III. Present and future",1993,"10.1086/173407","https://www.scopus.com/inward/record.uri?eid=2-s2.0-12044249666&doi=10.1086%2f173407&partnerID=40&md5=75112743067548f2993e7077b2f08129","Self-consistent evolutionary models were computed for our Sun, using Los Alamos interior opacities and Sharp molecular opacities, starting with contraction on the Hayashi track, and fitting the observed present solar L, R, and Z/X at the solar age. This resulted in presolar Y = 0.274 and Z = 0.01954, and in present solar 37Cl and 71Ga neutrino capture rates of 6.53 and 123 SNU, respectively. We explored the Sun's future. While on the hydrogen-burning main sequence, the Sun's luminosity grows from 0.7 L⊙, 4.5 Gyr ago, to 2.2 L⊙, 6.5 Gyr from now. A luminosity of 1.1 L⊙ will be reached in 1.1 Gyr, and 1.4 L⊙ in 3.5 Gyr; at these luminosities, Kasting predicts ""moist greenhouse"" and ""runaway greenhouse"" catastrophes, respectively, using a cloud-free climate model of the Earth; clouds could delay these catastrophes somewhat. As the Sun ascends the red giant branch (RGB), its convective envelope encompasses 75% of its mass (diluting remaining 7Li by two orders of magnitude; 4He is enhanced by 8%, 3He by a factor of 5.7, 13C by a factor of 3, and 14N by a factor of 1.5). The Sun eventually reaches a luminosity of 2300 L⊙ and a radius of 170 R⊙ on the RGB, shedding 0.275 M⊙ and engulfing the planet Mercury. After the horizontal branch stage (core helium burning), the Sun climbs the asymptotic giant branch (AGB), encountering four thermal pulses there; at the first thermal pulse, the Sun reaches its largest radial extent of 213 R⊙ (0.99 AU), which is surprisingly close to Earth's present orbit. However, at this point the Sun's mass has been reduced to 0.591 M⊙, and the orbits of Venus and Earth have moved out to 1.22 and 1.69 AU, respectively - they both escape being engulfed. The Sun reaches a peak luminosity of 5200 L⊙ at the fourth thermal pulse. It ends up as a white dwarf with a final mass of 0.541 M⊙, shifting the orbits of the planets outward such that Venus and Earth end up at 1.34 and 1.85 AU. respectively. These events on the AGB are strongly mass-loss dependent; somewhat less mass loss can result in engulfment of Venus, or even Earth. Our preferred mass-loss rate was a Reimers wind with a mass-loss parameter η = 0.6 normalized from inferred mass loss in globular cluster stars. For reasonable mass-loss rates (0.8 &gt; η &gt; 0.4), the Sun's final white dwarf mass is between 0.51 and 0.58 M⊙. The Sun spends 11 Gyr on the main sequence, 0.7 Gyr cooling toward the RGB, 0.6 Gyr ascending the RGB, 0.1 Gyr on the horizontal branch, 0.02 Gyr on the early AGB, 0.0004 Gyr on the thermally pulsing AGB, and 0.0001 Gyr on the traverse to the planetary nebula stage (the last three of these time scales depend sensitively on the amount of mass loss)."
"6602757925;7005311747;","Modeling Climate Related Feedback Processes",1993,"10.1080/10934529309375997","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027139084&doi=10.1080%2f10934529309375997&partnerID=40&md5=31ffcd1d22ab18bb2611cdcf53df1ef8","Feedback mechanisms play a crucial role in the climate system, amplifying or dampening the climate response to enhanced concentrations of greenhouse gases from anthropogenic perturbations. Many of these feedbacks are known, but most of them only potentially. This article evaluates the role of a number of these feedback processes within the climate system. In order to assess their impact, the feedbacks which at present can be quantified reasonably are built into the Integrated Model to Assess the Greenhouse Effect (IMAGE). Unlike previous studies, this study describes the scenario- and time-dependent role of biogeochemi-cal feedbacks. A number of simulation experiments are performed with IMAGE to project climate changes. Besides estimates of their absolute importance, the relative importance of individual biogeochemical feedbacks is considered by calculating the gain for each feedback process. This study focuses on feedback processes in the carbon cycle and the methane (semi-) cycle. Modeled feedbacks are then used to balance the past and present carbon budget. This results in substantially lower projections for atmospheric carbon dioxide than the Intergovernmental Panel on Climate Change (IPCC) estimates. The difference is approximately 18% from the 1990 level for the IPCC “Business-as-Usual” scenario. Furthermore, the IPCC's “best guess” value of the CO2 concentration in the year 2100 falls outside the uncertainty range estimated with our balanced modeling approach. For the IPCC “Business-as-Usual” scenario, the calculated total gain of the feedbacks within the carbon cycle appears to be negative, a result of the dominant role of the fertilization feedback. This study also shows that if temperature feedbacks on methane emissions from wetlands, rice paddies, and hydrates do materialize, methane concentrations might be increased by 30% by 2100. The total effect of the methane feedbacks and the carbon dioxide feedbacks modeled can be expressed in the carbon dioxide-equivalent concentrations. Our simulated CO2-equivalent concentrations are lower than the IPCC estimates. © 1993, Taylor & Francis Group, LLC. All rights reserved."
"7004375028;6602679348;6603788433;","The use of cosmic rays for continuous monitoring and prediction of some dangerous phenomena for the earth's civilization",1993,"10.1007/BF00658132","https://www.scopus.com/inward/record.uri?eid=2-s2.0-21344497090&doi=10.1007%2fBF00658132&partnerID=40&md5=260d0c87672437a151ad4c0d19eb1cf8","The main idea of the International Cosmic Ray Service (ICRS) is to combine satellite and spaceprobe cosmic rays, magnetic and plasma data with groundbased cosmic ray data (exchanged in real time) for obtaining continuous information on the electromagnetic and radiation situation in the interplanetary space and Earth's magnetosphere: prediction of great geomagnetic storms, big increases of radiation hazards and other dangerous phenomena in space and on the Earth for people and technology. ICRS can predict not only geomagnetic storms and unfavorable days in the environment (especially important for old people and people with some diseases), but, in combination with astrophysical methods, can predict big increases of radiation hazards very dangerous for the Earth's civilization and big changes in the environment due to extremely powerful solar flares and local supernova explosions. We hope that, after some additional investigation of high energy cosmic-ray distribution function outside the heliosphere, it could be possible to solve by ICRS more complicated problems: to determine in combination with astrophysical methods the location and velocity of nearest dust-molecular galactic clouds with frozen-in magnetic fields and predict the expected time of the Sun capturing by some clouds with possible changes of Earth's global climate. The foundation of ICRS could bring a new possibility of development to the cosmic ray observatories, release scientists from a lot of routine work and increase the fundamental and applied research efficiency. © 1993 Kluwer Academic Publishers."
"7202162685;7102968447;7007175473;","Impact of clouds on the surface radiation balance of the Arctic Ocean",1993,"10.1007/BF01030494","https://www.scopus.com/inward/record.uri?eid=2-s2.0-21144469196&doi=10.1007%2fBF01030494&partnerID=40&md5=856630dc158d091e1a8b2fa916cf9d4d","The relationship between clouds and the surface radiative fluxes over the Arctic Ocean are explored by conducting a series of modelling experiments using a one-dimensional thermodynamic sea ice model. The sensitivity of radiative flux to perturbations in cloud fraction and cloud optical depth are determined. These experiments illustrate the substantial effect that clouds have on the state of the sea ice and on the surface radiative fluxes. The effect of clouds on the net flux of radiation at the surface is very complex over the Arctic Ocean particularly due to the presence of the underlying sea ice. Owing to changes in surface albedo and temperature associated with changing cloud properties, there is a strong non-linearity between cloud properties and surface radiative fluxes. The model results are evaluated in three different contexts: 1) the sensitivity of the arctic surface radiation balance to uncertainties in cloud properties; 2) the impact of interannual variability in cloud characteristics on surface radiation fluxes and sea ice surface characteristics; and 3) the impact of climate change and the resulting changes in cloud properties on the surface radiation fluxes and sea ice characteristics. © 1993 Springer-Verlag."
"35468030800;56307442500;57213290884;","Fluctuation dissipation in a general circulation model",1993,"10.1007/BF00209665","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027798412&doi=10.1007%2fBF00209665&partnerID=40&md5=14f06ee1a6af7175ad783c357f4f100c","This paper considers the climate response to step function changes in the solar constant in two versions of a general circulation model with simplified geography. The NCAR CCM0 model is applied to an all-land planet with no topography (Terra Blanda). In one version there is moisture in the air (as well as self-generated clouds) as evaporated from an ideal surface at a fixed 80% of saturation. In the other version there is no moisture in the atmosphere. We examine the decay of natural anomalies in the large-scale temperature field in each model and compare the time dependence of the ensemble average with the average temporal behavior of the response to step function changes in the solar constant. The fluctuation-dissipation theorem of statistical mechanics makes specific predictions about the relationship between the two curves. We conduct the experiments for both versions of the model since the sensitivity is quite different for each. The theorem is found to hold reasonably well in each case. © 1993 Springer-Verlag."
"6602087295;6506581660;57198655623;","Rice production and climate change: design and development of a GIS database to complement simulation models",1993,"10.1007/BF00141588","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042469847&doi=10.1007%2fBF00141588&partnerID=40&md5=a1fbc91a679713717207c14424df3cc4","A cooperative project between the International Rice Research Institute in Los Baños, Philippines, and the U.S. EPA Environmental Research Laboratory in Corvallis, Oregon, was initiated to estimate how rice yield in Asia might be affected by future climate change and enhanced UV-B irradiance following stratospheric ozone depletion. A radiative transfer model was used to estimate daily UV-B irradiance levels using remotely sensed ozone and cloud cover data for 1274 meteorological stations. A rice yield model using daily climatic data and cultivar-specific coefficients was used to predict changes in yield under given climate change scenarios. This paper gives an overview of the data required to run these two models and describes how a geographical information system (GIS) was used as a data pre- or postprocessor. Problems in finding reliable datasets such as cloud cover data needed for the UV-B radiation model and radiation data needed for the rice yield model are discussed. Issues of spatial and temporal scales are also addressed. Using simulation models at large spatial scales helped identify weaknesses of GIS data overlay and interpolation capabilities. Even though we focussed our efforts on paddy rice, the database is not intended to be system specific and could also be used to analyze the response of other natural systems to climatic change. © 1993 SPB Academic Publishing bv."
"7005890514;","Climate change and the regulation of the surface moisture and energy budgets",1993,"10.1007/BF00198617","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799971&doi=10.1007%2fBF00198617&partnerID=40&md5=2558e9546cbbce2ff2209324343fe649","The increase in the vigor of the hydrological cycle simulated in a 2 × CO2 experiment with the Canadian Climate Centre general circulation model is smaller than that obtained by other models which have similar increases in mean surface temperature. The surface energy budget, which encompasses also the moisture budget for the oceans, is analyzed. Changes in the net radiative input to and sensible heat flux from the surface act to warm it. This is balanced, at the new equilibrium, by a change in the latent heat flux which acts to cool it. Although this same general behavior is seen in other models, the increase in radiative input to the surface in the CCC GCM is smaller than in other models while the change in the sensible heat flux is of similar size. As a consequence, the latent heat flux required for balance is smaller. The comparatively small increase in the net radiative input at the surface occurs because of a decrease in the solar component. On average the decrease in solar input in the tropical region outweighs the higher latitude increase associated with the snow/ice albedo feedback. The notable tropical decrease in solar input occurs because the albedo of the clouds increase enough in this region to outweigh a small decrease in cloud amount. The increase in cloud albedo in the warmer and moister tropical atmosphere is a consequence of the parameterized cloud optical properties in the model which play an important role in the regulation of the surface energy and moisture budgets. The results demonstrate some of the consequences of the negative feedback mechanism associated with increasing cloud albedo in the model. They also suggest that the simulated change in the vigor of the hydrological cycle is not a simple function of the average increase in surface temperature but is a consequence of all of the processes in the model which control the available energy at the surface as a function of latitude. © 1993 Springer-Verlag."
"7005965757;7006518289;","Greenhouse sensitivity experiments with penetrative cumulus convection and tropical cirrus albedo effects",1993,"10.1007/BF00198616","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027869897&doi=10.1007%2fBF00198616&partnerID=40&md5=fbba9d4313562cb2ec8802631d9596c9","Results are presented from two versions of a global R15 atmospheric general circulation model (GCM) coupled to a nondynamic, 50-m deep, slab ocean. Both versions include a penetrative convection scheme that has the effect of pumping more moisture higher into the troposphere. One also includes a simple prescribed functional dependence of cloud albedo in areas of high sea-surface temperature (SST) and deep convection. Previous analysis of observations has shown that in regions of high SST and deep convection, the upper-level cloud albedos increase as a result of the greater optical depth associated with increased moisture content. Based on these observations, we prescribe increased middle- and upper-level cloud albedos in regions of SST greater than 303 K where deep convection occurs. This crudely accounts for a type of cloud optical property feedback, but is well short of a computed cloud-optical property scheme. Since great uncertainty accompanies the formulation and tuning of such schemes, the prescribed albedo feedback is an intermediate step to examine basic feedbacks and sensitivities. We compare the two model versions (with earlier results from the same model with convective adjustment) to a model from the Canadian Climate Centre (CCC) having convective adjustment and a computed cloud optical properties feedback scheme and to several other GCMs. The addition of penetrative convection increases tropospheric moisture, cloud amount, and planetary albedo and decreases net solar input at the surface. However, the competing effect of increased downward infrared flux (from increased tropospheric moisture) causes a warmer surface and increased latent heat flux. Adding the prescribed cirrus albedo feedback decreases net solar input at the surface in the tropics, since the cloud albedos increase in regions of high SST and deep convection. Downward infrared radiation (from increased moisture) also increases, but this effect is overpowered by the reduced solar input in the tropics. Therefore, the surface is somewhat cooler in the tropics, latent heat flux decreases, and global average sensitivity to a doubling of CO2 with regard to temperature and precipitation/evaporation feedback is reduced. Similar processes, evident in the CCC model with convective adjustment and a computed cloud optical properties feedback scheme, occur over a somewhat expanded latitudinal range. The addition of penetrative convection produces global effects, as does the prescribed cirrus albedo feedback, although the strongest local effects of the latter occur in the tropics. © 1993 Springer-Verlag."
"7006581381;55431813200;","Tree-ring evidence for 1842-1843 eruptive activity at the Goat Rocks dome, Mount St. Helens, Washington",1993,"10.1007/BF00624354","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027488344&doi=10.1007%2fBF00624354&partnerID=40&md5=fde3004d7ce0cfd32b378c1140ba1287","Until the 18 May 1980 eruption of Mount St. Helens, a debris fan and adjacent forest downslope from the dacitic Goat Rocks dome, on the north flank of the volcano, contained evidence that the dome was active in 1842 or 1843. The fan was destroyed by the debris avalanche of 18 May. Before 1980, the oldest tree cored on the debris fan showed that the fan predated 1855 by a few years. The young age of this tree suggests that the dome was active several decades after extrusion of the nearby andesitic ""floating island"" lava flow, dated to 1800. An anomalous series of narrow rings that starts with the 1843 ring is present in cores from two older trees adjacent to the fan. These ring-width patterns imply that these trees were damaged in late 1842 or early 1843 by flowage material from the dome; the trees were probably singed by an ash-cloud surge that originated on the dome as a hot-rock avalanche. Several lines of evidence suggest that the anomalous ring patterns record tree injury by surge, rather than by lahars or nonvolcanic causes (climate or insects). First, comparable ring patterns formed in all sampled trees that survived the 18 May surge, but formed in only a few sampled trees abraded or partially buried by 18 May lahars. Second, a 13-cm fine-ash layer, consistent with either tephra fall or surge emplacement, was present on the 1840s forest floor; yet the lack of similar tree-ring responses to 1980 tephra fall shows that such minor tephra fall could not have caused the ring patterns. Third, identical 1843 narrow-ring patterns are absent in control trees further from the volcano. The ring patterns of the trees adjacent to the Goat Rocks fan provide the first field evidence that the dome was active in late 1842 or early 1843. Thus, the new tree-ring dates confirm stratigraphic evidence for the youth of the activity of the Goat Rocks dome. They also link historical accounts of mid nineteenth century volcanism at Mount St. Helen with continuing dome extrusion. The dates additionally corroborate and revise the dacite-andesite-dacite petrologic cycle interpretation of Mount St. Helens' Goat Rocks eruptive period (1800-1857). They constrain the cycle to no more than 43 years. Lastly, the dates support the notion that the vent that erupted the 1800 dacitic T tephra was different from the one that produced the Goat Rocks dome. We infer that the magma that formed the ""floating-island"" lava flow plugged the T tephra vent. This forced residual magma from the compositionally zoned magma chamber into an alternate conduit. The second conduit produced the unnamed 1842 lithic tephra and the Goat Rocks dome. © 1993 Springer-Verlag."
"7402565691;6701652335;","Long-term variability in the water balances of the Plynlimon catchments",1993,"10.1016/0022-1694(93)90199-J","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027334604&doi=10.1016%2f0022-1694%2893%2990199-J&partnerID=40&md5=166c7dff0759d63fd86d2b3c19dfa433","Water balance data have been collected since 1969 from the Institute of Hydrology's long-term experiment on Plynlimon, Mid-Wales, with the primary aim of quantifying the differences in evaporation between the 67% forested Severn and the grassland Wye catchments. Evaporation differences between the two catchments, and hence between the two land uses, have been established with increasing precision as the experiment has proceeded; however, the absolute hydrological responses to natural and man-induced fluctuations in climate take longer to quantify. Analysis of trends in time series data from the catchments indicates increased rainfall and flow over the study period, particularly during the summer, with the difference between them, actual evaporation, declining markedly in both main and sub-catchments. A partial explanation for the reduction implicates a decline in atmospheric demand for moisture, caused by increased cloud interception of incoming radiation, colder air temperatures which lead to a lowering of the vapour capacity of the atmosphere and, most markedly, a decline of 30% in specific humidity deficits above the crop. Other potential physiological controls are discussed, including changes in atmospheric carbon dioxide and tree root damage by acid rain. © 1993."
"16185051500;","Aerosol-cloud-climate interactions",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84891384734&partnerID=40&md5=792b6e7e804aaa620cea85b714376afc","This book provides an overview of the latest research on atmospheric aerosol and clouds and their effect on global climate. Subjects reviewed include the direct and indirect effects of aerosols on climate; the radiative properties of clouds and their effect on the earth's radiation balance; the incorporation of cloud effects in numerical weather prediction models; and stratospheric aerosols and clouds. All chapters are abstracted separately. -from Publisher"
"7202145115;","Radiative effects of clouds on Earth's climate",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027842161&partnerID=40&md5=cdb4c6b5888785818fabf7adda7497be","Recent efforts have used radiation budget data in conjunction with cloud descriptions based on satellite data to estimate the importance of various cloud types in the energy balance of Earth. Low stratus clouds and tropical convective anvil clouds play very important roles in radiative forcing of climate. High-latitude clouds, especially those over the oceans, provide a strong negative cloud forcing during the summer, which results in an increase in the required equator-to-pole energy transport. -from Author"
"7407116104;7006393267;","An accurate parameterization of the radiative properties of water clouds suitable for use in climate models",1993,"10.1175/1520-0442(1993)006<0728:AAPOTR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027528264&doi=10.1175%2f1520-0442%281993%29006%3c0728%3aAAPOTR%3e2.0.CO%3b2&partnerID=40&md5=d937e2bce2bb1c2823f31c04d934bb20","Cloud optical properties for both solar and terrestrial spectra and for cloud equivalent radii in the range 2.5-60 μm are calculated from Mie theory. It is found that cloud optical properties depend mainly on equivalent radius throughout the solar and terrestrial spectrum and are insensitive to the details of the droplet size distribution, such as shape, skewness, width, and modality (single or biomodal). This suggests that in cloud models, aimed at predicting the evolution of cloud microphysics with climate change, it is sufficient to determine the third and the second moments of the size distribution (the ratio of which determines the equivalent radius). It also implies that measurements of the cloud liquid water content and the extinction coefficient are sufficient to determine cloud optical properties experimentally (i.e., measuring the complete droplet size distribution is not required). -from Authors"
"7004540083;6506841622;","Cloud detection using satellite measurements of infrared and visible radiances for ISCCP",1993,"10.1175/1520-0442(1993)006<2341:CDUSMO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027789430&doi=10.1175%2f1520-0442%281993%29006%3c2341%3aCDUSMO%3e2.0.CO%3b2&partnerID=40&md5=135105b22744a691116991edd830af69","The International Satellite Cloud Climatology Project (ISCCP) began in 1983 to collect and analyze weather satellite radiance datasets to produce a new global cloud climatology as part of the World Climate Research Programme. This paper, the first of three, describes the cloud detection part of the ISCCP analysis. Key features of the cloud detection algorithm are 1) use of space and time radiance variation tests over several different space and time domains to account for the global variety of cloudy and clear characteristics, 2) estimation of clear radiance values for every time and place, and 3) use of radiance thresholds that vary with type of surface and climate regime. The sensitivity of the results to changing test parameter values is determined to provide a first estimate of the uncertainty of ISCCP cloud amounts. -from Authors"
"7004764167;7406514318;","Carbon dioxide and climate: the impact of cloud parameterization",1993,"10.1175/1520-0442(1993)006<0393:CDACTI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027532797&doi=10.1175%2f1520-0442%281993%29006%3c0393%3aCDACTI%3e2.0.CO%3b2&partnerID=40&md5=c2edeba0874d6d98829d25e50f0fc455","The importance of the representation of cloud in a general circulation model is investigated by utilizing four different parameterization schemes for layer cloud in a low-resolution version of the general circulation model. The performance of each version of the model in terms of cloud and radiation is assessed in relation to satellite data from the Earth Radiation Budget Experiment (ERBE). Schemes that include a prognostic cloud water variable show some improvement on those with relative humidity-dependent cloud, but all still show marked differences from the ERBE data. The sensitivity of each of the versions of the model to a doubling of atmospheric CO2 is investigated. Using an energy balance model, it is estimated that the climate sensitivity using the relative humidity scheme along with the negative feedback from cloud radiative properties would be 2.8°C. Thus, 2.8°-2.1°C appears to be a better estimate of the range of equilibrium response to a doubling of CO2. -from Authors"
"7202145115;","Radiative Effects of Clouds on Earth's Climate",1993,"10.1016/S0074-6142(08)60215-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956857401&doi=10.1016%2fS0074-6142%2808%2960215-6&partnerID=40&md5=e3d2972cfc9cb4f34a56fd9b8c3521cc","This chapter discusses the radiative effects of clouds on Earth's climate. Suspensions of liquid water and ice in the atmosphere have a dramatic influence on the reflection and absorption of solar radiation and on the emission and absorption of terrestrial radiation. These radiative effects of clouds are important for the energy balance of Earth, and for physical, dynamical, chemical, and biological processes within the climate system. Cloud radiative effects reduce seasonal variations in the two hemispheres, because the cloud forcing reduces the amplitude of the annual cycle in hemispheric net radiation, primarily by reducing the absorption of solar radiation during summer. Cloud radiative effects change the overall planetary energy budget and are important in determining the distribution of energy between the atmosphere and the surface. Because the cloud-free atmosphere is relatively transparent to solar radiation and opaque to terrestrial radiation, the reflection of solar radiation by clouds affects the surface energy budget most directly, and the reduction in longwave cooling is felt primarily as a reduction in energy lost from the atmosphere. In this respect convective clouds are self-limiting to some extent, because their radiative effects reduce the radiative destabilization of the atmosphere that generates the need for convection. © 1993, Academic Press Inc."
"7202185413;","45 O 04 In-cloud measurements of effective droplet radius",1993,"10.1016/0021-8502(93)90384-L","https://www.scopus.com/inward/record.uri?eid=2-s2.0-38249006824&doi=10.1016%2f0021-8502%2893%2990384-L&partnerID=40&md5=c3622940db43ad30fed600423128bf2f",[No abstract available]
"57197153242;","An empirical analysis of the strength of the phytoplankton- dimethylsulfide-cloud-climate feedback cycle",1993,"10.1029/93jd01930","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1842618219&doi=10.1029%2f93jd01930&partnerID=40&md5=fc1927c500dbc9f50c25223a35a9e513","By considering available data on the relationships between individual components of the proposed feedback, an empirical model is developed of the cycle as a whole, allowing an assessment to be made of the degree to which the cycle could thermostatically regulate the climate. It is estimated that the feedback strength is about 20% (10%-50%) of that which would be necessary to completely counteract a perturbation to the global climate, such as is anticipated due to accumulation of anthropogenic greenhouse gases. -from Author"
"7402215419;","A general solution for stochastic radiative transfer",1993,"10.1029/93GL02347","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027846658&doi=10.1029%2f93GL02347&partnerID=40&md5=7417637c7c746e431f600156e2771002","The three‐dimensional variability of clouds has an important impact on the transfer of radiation in the Earth's atmosphere, and thus the current practice in climate modeling of assuming clouds are horizontally homogeneous entails significant errors. A new method, based on the backward Monte Carlo technique, has been developed for computing the mean outgoing radiation field from any type of stochastic ensemble of cloud structure. The accuracy of the technique has been verified by comparison with many realizations of deterministic radiative transfer. The method illustrates how spatial variability should be defined, and should lead to improved representations of the radiative effects of clouds in climate models. Copyright 1993 by the American Geophysical Union."
"56157800800;24348741300;7202988622;","Precambrian climate: the effects of land area and Earth's rotation rate",1993,"10.1029/93JD00033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027444139&doi=10.1029%2f93JD00033&partnerID=40&md5=0e87a1781272cb59d12b6fb9ab9799d6","The associated climate changes are examined with a general circulation model (GCM) and compared with the current climate state. We show that rotation rate changes can affect mean air temperatures by strongly affecting the cloud field. For example, an Earth day length of 14 hours causes the global mean cloud fraction to decrease 20%. There are also large changes in the wind field; indeed, at some mid-latitudes the time-averaged surface wind changes from westerlies to easterlies. If the land masses are removed from the model and with present-day rotation, the global mean air temperature is 4 K higher than for the present-day simulation. -from Authors"
"7004462010;","Water cycle and feedbacks in global climate change",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027795468&partnerID=40&md5=7733f111ea41ffe1ae6cd4c6a1009782","The importance of such climate-forming factors as sea surface temperature anomalies, cloud-radiation interaction, and volcanic eruptions is discussed. The necessity to further investigate the internal dynamics of the interactive atmosphere-hydrosphere-cryosphere-lithosphere-biosphere climate system and anthropogenic impact on the system is emphasized. -Author"
"57203400519;","Aerosol-climate interactions",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027794920&partnerID=40&md5=6f8a0a28ae7fe57f62fe093ea0ff2037","Particulate matter of submicrometer size in the earth's atmosphere perturbs the radiation field sufficiently to warrant its consideration in any discussion of processes that maintain the current climate. The anthropogenic component of this aerosol burden causes a direct negative (ie cooling) radiative forcing of about 1.0 to 2.0 W m-2 in the shortwave, which is comparable but of opposite sign to the positive longwave forcing of several trace (""greenhouse') gases associated with industrial and agricultural activities. However, this shortwave forcing is roughly equal to that which would result from an absolute change in global cloud cover of only 1-2%. Therefore, global monitoring efforts and attempts at incorporating aerosols into climate models will invariably be hampered by clouds. -from Author"
"57196171136;7005070958;","Effect of anthropogenic sulfate aerosols on low-level cloud albedo over oceans",1993,"10.1029/93jd01211","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000915353&doi=10.1029%2f93jd01211&partnerID=40&md5=4097841092204c17206663de5c48bc7b","By reducing cloud droplet size, anthropogenic sulfate aerosols are capable of increasing cloud albedo and thus possibly changing the climate. To test the detectability of this effect, we examined satellite-measured low-level cloud albedo off the east coasts of North America and Asia at mid-latitudes where anthropogenic sulfate sources are large and aerosols are transported eastward over the oceans by prevailing westerlies. The satellite data demonstrate enhanced cloud albedo near the coastal boundaries where sulfate concentrations are large. Similar trends are absent over ocean regions of the southern hemisphere that are removed from anthropogenic sulfate sources. -Authors"
[No author id available],"The GEWEX cloud system study (GCSS)",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027880975&partnerID=40&md5=56bba4e5037d05caa8b92c1cc969ac55","The World Climate Research Programme's Global Energy and Water Cycle Experiment (GEWEX) addresses both the hydrological and meteorological components of the water cycle. The Joint Scientific Committee of WCRP at its 1992 meeting approved the establishment of a GEWEX Cloud System Study (GCSS) as a long-term program that will address these issues mainly through the development of cloud-resolving models and their use to generate realizations of a set of archetypal cloud systems. The focus of GCSS is on cloud systems spanning the mesoscale rather than on individual clouds. Observations from field programs will be used to develop and validate the cloud-resolving models, which in turn will be used as test-beds to develop the parameterizations for the large-scale models. -from Authors"
"7402598670;7006259827;7103293232;","The integrated percent likelihood overcast parameter: a new estimate of cloud coverage from satellite data",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027802752&partnerID=40&md5=7a25f402f730dfd12494b0aae9c6d519","The ability to accurately estimate cloud coverage is a crucial step for many global climate study applications. The determination of this important parameter has proven difficult in practice. A new method of estimating cloud coverage at the original data resolution from a single IR parameter is presented here. Using a set of twelve AVHRR images of clouds over water in February 1986 IR parameters minimum, maximum and mean are extracted. A maximum likelihood classifier is used to extract a mapping between RI digital number and relative cloud coverage. -from Authors"
"7409600730;6603239832;7202163945;7409671103;7003899619;","Comparison of an experimental NOAA AVHRR cloud dataset with other observed and forecast cloud datasets",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027840525&partnerID=40&md5=eadcab0635bad7782cf7fd82db1e1ad0","CLAVR [cloud from AVHRR (Advanced Very High Resolution Radiometer)] is a global cloud dataset under development at NOAA/NESDIS (National Environmental Satellite, Data, and Information Service). Total cloud amount from two experimental cases, 9 July 1986 and 9 February 1990, are intercompared with two independent products, the Air Force Real-time Nephanalysis (RTNEPH), and the International Satellite Cloud Climatology Project (ISCCP). The ISCCP cloud database is a climate product processed retrospectively some years after the data are collected. Thus, only CLAVR and RTNEPH can satisfy the real-time requirements for numerical weather prediction (NWP) models. Results suggest that if the satellite cloud data is available in real time, it can be used to improve the cloud parameterization in numerical forecast models and data assimilation systems. -from Authors"
"7402565763;","Cloud condensation nuclei",1993,"10.1175/1520-0450(1993)032<0596:CCN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027798427&doi=10.1175%2f1520-0450%281993%29032%3c0596%3aCCN%3e2.0.CO%3b2&partnerID=40&md5=34cefa3df53da36b692d245d5b521b55","The state of knowledge of the particles upon which liquid droplets condense to form atmospheric water clouds is presented. The realization of cloud condensation nuclei (CCN) as a distinct aerosol subset originated with the cloud microphysical measurements and theoretical insights of Patrick Squires 40 years ago. He helped originate and continue the development of CCN counters and made significant CCN measurements for more than 25 years. Recognition of the importance of CCN has expanded from warm-rain efficiency to aerosol scavenging, cloud radiative properties, and other topics. In spite of a promising beginning and much encouragement over the years, CCN knowledge has increased minimally. Significant uncertainties about global climate change cannot be reduced without expansion of the knowledge base of CCN. -Author"
"16185051500;7005882490;7004546686;","Recent field studies of sulfur gases, particles and clouds in clean marine air and their significance with respect to the DMS-cloud- climate hypothesis",1993,"10.1007/978-94-017-1261-3_37","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027883788&doi=10.1007%2f978-94-017-1261-3_37&partnerID=40&md5=eb8e2166ff2f5193f8441cdf9cfbbc75","DMS concentrations in the marine boundary layer over the Pacific Ocean varied seasonally from as little as a few to several hundred pptv and tended to decrease from the surface up to the top of the marine boundary layer. DMS concentrations over the Arctic Ocean ranged from a few pptv in early June to ~300pptv later in the month; the latter concentration is among the highest ever measured. The concentrations of DMS were large enough to account for most of the measured SO2 and NSS sulfate. DMS and CCN are correlated, but not by the same linear relation at all supersaturations. Cases of new particle production, in and around clouds, have been documented. We attribute this to the homogeneous-bimolecular oxidation of SO2. -from Authors"
"16185051500;","Aerosol-Cloud Interactions",1993,"10.1016/S0074-6142(08)60211-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956864115&doi=10.1016%2fS0074-6142%2808%2960211-9&partnerID=40&md5=938dc4c246b09b408002cc1b4a8e7c01","This chapter presents a review of two of the aerosol–cloud–climate interactions: the effects of atmospheric aerosol on clouds, and the effects of clouds on atmospheric aerosol. The corresponding aerosol–cloud interactions over the continents are depicted. The main sources of sulfur and nitrogen gases are from anthropogenic and biomass combustion. These gases can be absorbed into cloud particles; they are oxidized to form aerosol, some of which can serve as cloud condensation nuclei (CCN). CCN are also injected directly into the atmosphere from the Earth's surface. Aqueous-phase chemical reactions in clouds can enhance the activity of CCN released from evaporating clouds. Also, in-cloud chemical reactions are probably often the main mechanism for acidifying cloud water and precipitation in polluted air, with nucleation scavenging and below-cloud removal generally playing important but lesser roles. Clouds and precipitation are important sinks for atmospheric aerosol. This affects the size distribution and chemical nature of atmospheric aerosol and the chemical composition of clouds and precipitation. In addition to modifying existing aerosol, some recent research indicates that clouds can be involved in the nucleation of new aerosol. © 1993, Academic Press Inc."
"7005729142;","Microphysical structures of stratiform and cirrus clouds",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027866178&partnerID=40&md5=70970499075d37e08c6c627fc7944144","This chapter summarizes measurements of the physical and microphysical structures of stratus, stratocumulus, altostratus, and cirrus clouds, which are thought to have the greatest effect on climate bcause of the large areas they cover. These clouds can be loosely classified according to the phase(s) of the condensate: liquid, mixed-phase, and ice, respectively. Summaries of the microphysical properties, frequencies of occurrence, physical appearances, and heights and thicknesses of each of these cloud types are presented. The chapter draws on previously reported as well as unreported measurements. -Author"
"24309903400;24310136800;7004944741;7005719900;","Parameterization model of the radiative distribution in an atmospheric column, taking into account the cloud cover: application to Kuwait's fires",1993,"10.1016/0266-9838(93)90021-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-43949173100&doi=10.1016%2f0266-9838%2893%2990021-9&partnerID=40&md5=4f26356a438c4034fbd615e322deb9e2","A 1-D model is presented for calculations of both longwave and shortwave radiant flux distribution along the atmospheric column, in order to study the effect of various energy scenarios on the global climate change. The model evaluates the radiative balance terms relative to the various atmospheric layers, which also take into account the formation and the effects produced by stratified clouds. The computer code consists of two blocks: the first block evaluates the optical properties of the cloud layer, while the latter determines the radiative balance. The paper presents the application of the model to the analysis of the radiative transfer processes which took place in the atmosphere containing the combustion products of the oil well fires above Kuwait. The results fit the observational data of the surface temperature change, giving a first validation of the adequacy of the model in studying well-defined climatic problems. © 1993."
"7402064802;7202145115;","Spurious changes in the ISCCP dataset",1993,"10.1029/93GL00211","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027386521&doi=10.1029%2f93GL00211&partnerID=40&md5=99985000554e65f5cd9b623d396ead0a","A long‐term decrease in mean cloud optical depth and mean cloud top temperature exists in the International Satellite Cloud Climatology Project (ISCCP) dataset for the July 1983 to December 1990 time period equatorward of 50° latitude. The decrease in optical depth of 2 is large compared to its mean of 4.6 for this period. The nature of this decrease suggests that it is not real, but rather an artifact of incomplete normalization of the visible channel on successive polar orbiters used as the calibration standard for ISCCP. This decrease has large impacts on the amounts of different cloud types defined by ISCCP, especially for cloud types whose mean amount is small. The decrease in mean cloud top temperature of 5 K has a smaller effect on the amounts of various cloud types. More accurate calibration techniques are needed in order to establish long‐term climate trends from ISCCP. Copyright 1993 by the American Geophysical Union."
"57202303479;7406343751;56959736200;","The microphysical feedback of cirrus cloud in climate change",1993,"10.2151/jmsj1965.71.6_701","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2042508056&doi=10.2151%2fjmsj1965.71.6_701&partnerID=40&md5=79893da3acc529742e5ccfd8694dfefd","The feedback effects of cirrus clouds in climate change are investigated, taking account of the temperature dependence of both ice water content and size distribution. The sensitivity parameter which is defined as a sum of partial derivatives is calculated with an accurate radiation code applying the 4-stream discrete-ordinates method and the method of exponential-sum fitting for gaseous transmission (ESFT). Microphysical properties of cirrus clouds are parameterized in terms of the cloud temperature from the data of aircraft observations. The value of ∂H/∂[IWC] × ∂[IWC]/∂T, i.e., a product of partial derivatives associated with ice water content feedback, is estimated to be 1.3–2.3 W m−2°C−1, meaning a positive feedback effect, and the value of ∂H/∂[SD] × ∂[SD]/∂T which is associated with size distribution feedback is estimated to be −0.1–−1.8 Wm−2°C−1, meaning a negative feedback effect. The positive ice water content feedback is significantly cancelled by the negative size distribution feedback especially at cloud temperature in the vicinity of −45°C. It is thus shown that the temperature dependence not only of ice water content but also of size distribution is important to estimate the microphysical feedback of cirrus cloud. © 1993, Meteorological Society of Japan."
"6603956591;7004098386;","Dimethylsulphide: oceans, atmosphere and climate. Proceedings of the international symposium, Belgirate, October 1992",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041146434&partnerID=40&md5=4d91c5fb23e0284e4c92f1e0ed0ba295","This book consists of the proceedings of an international symposium held in Belgirate, (Italy 13-15 Oct. 1992) and covers a wide range of topics concerning biogenic DMS, presented by many of the leading researchers in this field. ""Production by Marine Phytoplankton' and ""field measurements' cover studies of DMS cycling and production in air and water and include biological aspects (DMSP, algal species, nutrients, zooplankton grazing, bacteria, modelling) and atmospheric topics (MSA, SO4=, SO2, aerosol, size fractionation, seasonality, gas-to-particle conversion and CCN). ""Atmospheric Chemistry' and ""Gas-to-Particle Conversion and CCN production' cover field, lab and modelling studies of DMS oxidation mechanisms, rates and yields of many products, including cloud condensation nucleii. The last heading, ""Global Modelling and Climatic Implications' addresses the role of DMS in cloud formation, radiation fluxes and the potential for climate feedback.-P.Liss -P.Liss"
"56227108400;55207447000;7004568343;6701743200;","Seasonal, latitudinal, and secular variations in temperature trend: Evidence for influence of anthropogenic sulfate",1993,"10.1029/93GL02808","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027872526&doi=10.1029%2f93GL02808&partnerID=40&md5=cbff7d95bcbc1b740a524a5d4175411f","Tropospheric aerosols increase the shortwave reflectivity of the Earth‐atmosphere system both by scattering light directly, in the absence of clouds, and by enhancing cloud reflectivity. The radiative forcing of climate exerted by anthropogenic sulfate aerosols, derived mainly from SO2 emitted from fossil fuel combustion, is opposite that due to anthropogenic greenhouse gases and is estimated to be of comparable average magnitude in Northern Hemisphere midlatitudes. However, persuasive evidence of climate response to this forcing has thus far been lacking. Here we examine patterns of seasonal and latitudinal variations in temperature anomaly trend for evidence of such a response. Pronounced minima in the rate of temperature increase in summer months in Northern Hemisphere midlatitudes are consistent with the latitudinal distribution of anthropogenic sulfate and changes in the rate of SO2 emissions over the industrial era. Copyright 1993 by the American Geophysical Union."
"7004540083;6506841622;","Validation of ISCCP cloud detections",1993,"10.1175/1520-0442(1993)006<2370:VOICD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799926&doi=10.1175%2f1520-0442%281993%29006%3c2370%3aVOICD%3e2.0.CO%3b2&partnerID=40&md5=0224b1f5b0aaf8c0f9444b6496e07bb9","The International Satellite Cloud Climatology Project (ISCCP) began in 1983 to collect and analyze weather satellite datasets to produce a new global cloud climatology as part of the World Climate Research Programme. The first step of the analysis is detection of the presence of clouds at each location and time by a series of tests on the space/time variations of infrared and visible radiances. This paper describes the validation of the ISCCP cloud detections by verifying the accuracy of the inferred clear-sky radiances. Comparison of retrieved surface temperatures to other measurements shows that bias errors are <2 K and random errors are about 2 K for sea surface (monthly means at 280-km scales) and that bias errors are <2 K and random errors are about 4 K for land surfaces (3 hourly at 280-km scale). Bias errors over a few persistently cloudy locations are sometimes -(2.4) K and over winter sea ice may be about +2 K. -from Authors"
"35464731600;7409509094;","Model simulations of the competing climatic effects of SO2 and CO2",1993,"10.1175/1520-0442(1993)006<1241:MSOTCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027836784&doi=10.1175%2f1520-0442%281993%29006%3c1241%3aMSOTCC%3e2.0.CO%3b2&partnerID=40&md5=e2457f6b1ef3c46d10baf988ea3b5a81","Sulfur dioxide-derived cloud condensation nuclei are expected to enhance the planetary albedo, thereby cooling the planet. This effect might counteract the global warming expected from enhanced greenhouse gases. A detailed treatment of the relationship between fossil fuel burning and the SO2 effect on cloud albedo is implemented in a two-dimensional model for assessing the climate impact. Using a conservative approach, results show that the cooling induced by the SO2 emission can presently counteract 50% of the CO2 greenhouse warming. Since 1980, a strong warming trend has been predicted by the model, 0.15°C, during the 1989-1990 period alone. The model predicts that by the year 2060 the SO2 cooling reduces climate warming by 0.5°C or 25% for the Intergovernmental Panel on Climate Change (IPCC) business as usual (BAU) scenario and 0.2°C or 20% for scenario D (for a slow pace of fossil fuel burning). Despite the fact that most of the SO2-induced cooling takes place in the Northern Hemispheric continents, the model-predicted difference in the temperature response between the NH and the SH of -0.2°C in 1980 is expected to remain about the same at least until 2060. This result is a combined effect of the much faster response of the continents than the oceans and of the larger forcing due to CO2 than due to the SO2. The climatic response to a complete filtering of SO2 from the emission products in order to reduce acid rain is a warming surge of 0.4°C in the first few years after the elimination of SO2 emission. -from Authors"
"57190902278;","Multi‐year statistics of selected variable from the ISCCP C2 data set",1993,"10.1002/qj.49711951210","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027838704&doi=10.1002%2fqj.49711951210&partnerID=40&md5=bcf9d76271ec9580a8f34e6c1182318b","Coarse spatial resolution monthly statistics of selected variables of the International Satellite Cloud Climatology Project (ISCCP) C2 data set are analysed. The total cloud amount statistics are compared with those from conventional surface observations available from the Consolidated Ocean‐Atmosphere Data Set (COADS). These statistics include annual means and intra‐annual variances and correlations with the COADS sea surface temperature and surface relative humidity. In general the ISCCP C2 total cloud amount statistics are found to be in very good agreement with those of the COADS. In particular a number of correlation patterns are evident which are explainable in terms of known climatology, and which might be utilized as verification diagnostics for forecast and climate models. Preliminary analyses of the ISCCP C2 cloud‐top pressure and cloud water content have also been carried out. The annual means and intra‐annual standard deviations of these parameters appears to be consistent with surface cloud‐type observations. Furthermore, the intra‐annual variations of cloud‐top pressure and cloud water all have broad regions with significant correlations with sea surface temperature. Copyright © 1993 Royal Meteorological Society"
"7003770842;7202222714;7004508111;8666820400;57203088526;","Modelling of the sulphur cycle. From DMS to cloud particles",1993,"10.1007/978-94-017-1261-3_38","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027794317&doi=10.1007%2f978-94-017-1261-3_38&partnerID=40&md5=9b0d084fc314a80ca3951beaa163b152","A model of the sulphur cycle is being assembled to assist in the investigation of the roles of DMS and of anthropogenic sulphur in climate change. At present the model consists of two modules: AERO2, a model for aerosol dynamics and LPMR, a simplified model for cloud particle growth in cumulus clouds. In the present paper AERO2 is briefly described, with reference to the existing literature. For the newest module LPMR a description of the relevant equations is given together with the results of a verification exercise conducted on 4 test cases available in the literature. The performances of the statistical driver are exemplified with references to the model AERO2 in its ""reaction chamber' and ""field' versions. -from Authors"
"7006977548;7101832608;","Climate-volcanism feedback and the toba eruption of ∼74,000 years ago",1993,"10.1006/qres.1993.1081","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027882906&doi=10.1006%2fqres.1993.1081&partnerID=40&md5=7cb49be47210f0af6ed52a3885b67987","A general feedback between volcanism and climate at times of transition in the Quaternary climate record is suggested, exemplified by events accompanying the Toba eruption (∼74,000 yr ago), the largest known late Quaternary explosive volcanic eruption. The Toba paroxysm occurred during the δ18O stage 5a-4 transition, a period of rapid ice growth and falling global sea level, which may have been a factor in creating stresses that triggered the volcanic event. Toba is estimated to have produced between 1015 and 1016 g of fine ash and sulfur gases lofted in co-ignimbrite ash clouds to heights of at least 32 ± 5 km, which may have led to dense stratospheric dust and sulfuric acid aerosol clouds. These conditions could have created a brief, dramatic cooling or “volcanic winter,” followed by estimated annual Northern Hemisphere surface-temperature decreases of ∼3° to 5°C caused by the longer-lived aerosols. Summer temperature decreases of ≥10°C at high northern latitudes, adjacent to regions already covered by snow and ice, might have increased snow cover and sea-ice extent, accelerating the global cooling already in progress. Evidence for such climate-volcanic feedback, following Milankovitch periodicities, is found at several climatic transitions. © 1993 University of Washington."
"6602184993;7006212327;7004249622;6602458473;6504227066;","One year of cloud lidar data from Dumont d'Urville (Antarctica) 1. General overview of geometrical and optical properties",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027846452&partnerID=40&md5=6c61f96963afef084cc49a56269fc37a","Tropospheric clouds play a major role in climate regulation but, so far, only a few long-term ground-based observations, devoted to the study of the cloud optical and radiative properties, have been carried out. In this work the statistics of one year of coastal Antarctic cloud lidar measurements (532 nm) are shown. Cloud macrophysical and optical parameters have been retrieved from lidar returns; radiosonde data allowed us to build statistics of such quantities in terms of cloud temperature. Information about the physical phase of water and ice crystal habit has been otbained from the depolarization and extinction/backscattering ratio; a change in crystal habit (and/or size) around -30°C is evidenced by the depolarization versus temperature behaviour. The extinction/backscattering ratio shows a negative trend with temperature, reflecting microphysical changes. Visible extinction shows wide data dispersion, but with a marked negative trend with temperature. The relative derivatives of extinction and optical depth with temperature have been computed, such quantities result quite constant with temperature. -Authors"
"7202899330;7202208382;7801466353;6603565405;6603533215;","The Earth's radiation budget and its relation to atmospheric hydrology 3. Comparison of observations over the oceans with a GCM",1993,"10.1029/92JD02520","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027426609&doi=10.1029%2f92JD02520&partnerID=40&md5=a20cbe817d825acc1dc8def16cf4e3f4","The specific relationships examined in this paper include the sensitivities of column-integrated water vapor, the clear sky greenhouse effect, cloud albedo, and cloud radiative forcing to sea surface temperature. The second test focuses on comparison of simulated and observed seasonal cycles of the greenhouse effect and cloud radiative forcing. The main results of this study suggest that the model studied, which we take to be representative of the current generation of global climate models, is able to simulate some aspects of the observed sensitivities fairly well. -from Authors"
"7005729142;","Microphysical Structures of Stratiform and Cirrus Clouds",1993,"10.1016/S0074-6142(08)60213-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34247600918&doi=10.1016%2fS0074-6142%2808%2960213-2&partnerID=40&md5=83e9a5f1a42691cf8654580c698ea000","This chapter summarizes measurements of the physical and microphysical structures of stratus, stratocumulus, altostratus, and cirrus clouds, which are thought to have the greatest effect on climate because of the large areas they cover. These clouds can be loosely classified according to the phase(s) of the condensate: liquid, mixed-phase, and ice, respectively. Stratus clouds are layers or patches of low, often grey, clouds that hardly have definition and rarely produce precipitation. Altostratus clouds appear as gray or bluish sheets or layers, ranging from several hundreds to thousands of meters thick, often covering the entire sky. The layers are variously striated, fibrous, or uniform in aspect. Altocumulus clouds form in the mid-troposphere, in distinct layers often less than 100 m thick. From the ground, altocumulus clouds are identified by their sharp outlines, enclosing rounded often convective elements. Cirrus are detached clouds in the form of white, delicate filaments or mostly white patches or narrow bands, composed almost exclusively of ice crystals. Dense patches or tufts of cirrus may contain ice crystals large enough to acquire appreciable fallspeeds; extended trails of virga may sometimes be seen below such clouds. Wind shear and particle size affect the shape of the trails. One cirrus type displaying these features is cirrus uncinus; it is comma-shaped, terminating at the top in a hook or tuft, which is presumably an ice generation region. © 1993, Academic Press Inc."
"35557549500;57195670630;56162179300;6701653152;7409854743;7409895558;","Variation of sulfate aerosol concentrations over the western Pacific and their effect on clouds, radiation and precipitation",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027881035&partnerID=40&md5=dbcfff31c5283008119c8a8121e5e413","Under bilateral cooperation between the United States of America and the People's Republic of China, a series of research cruises were conducted over the western Pacific Ocean. It was found that a) the non-sea-salt sulfate aerosol particles are the major source of cloud condensation nuclei, b) the population of clouds and the total albedo are proportional to the concentration of condensation nuclei and consequently to the concentration of the non-sea-salt aerosol particles, and c) the amount of rainfall is inversely proportional to the concentration of non-sea-salt sulfate aerosol particles. It seems that anthropogenic sulfate aerosol particles affect the regional planetary albedo and climate and that the contribution from biogenically derived sulfate aerosol particles is of lesser importance. -Authors"
"7202418453;","Scientific investigations planned for the lidar in-space technology experiment (LITE)",1993,"10.1175/1520-0477(1993)074<0205:SIPFTL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027796741&doi=10.1175%2f1520-0477%281993%29074%3c0205%3aSIPFTL%3e2.0.CO%3b2&partnerID=40&md5=c00994b2a7c235f7a4a716c333038e99","The Lidar In-Space Technology Experiment (LITE) is being developed by NASA/Langley Research Center for a series of flights on the space shuttle beginning in 1994. Employing a three-wave-length Nd:YAG laser and a 1-m-diameter telescope, the system is test-bed for the development of technology required for future operational spaceborne lidars. The system has been designed to observe clouds, tropospheric and stratospheric aerosols, characteristics of the planetary boundary layer, and stratospheric density and temperature perturbations with much greater resolution than is available from current orbiting sensors. In addition to providing unique datasets on these phenomena, the data obtained will be useful in improving retrieval algorithms currently in use. Observations of clouds and the planetary boundary layer will aid in the development of global climate model (GCM) parameterizations. -from Authors"
"57203400519;","Aerosol-Climate Interactions",1993,"10.1016/S0074-6142(08)60212-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956843530&doi=10.1016%2fS0074-6142%2808%2960212-0&partnerID=40&md5=ba248d6c7a0b94779336dd06a0f0b87d","This chapter discusses the aerosol–climate interactions and is devoted to the direct radiative effects of aerosols. Aerosol layers are composed of submicrometer-sized particles that can be treated independently of the larger particles in clouds in a radiative budget of the Earth's atmosphere. The place of direct radiative forcing by tropospheric aerosols in the overall scheme of aerosol–climate interactions is presented. Any estimates of direct radiative forcing by aerosols can only be translated into a climate response by accepting the verisimilitude of current climate models. The relationship between direct radiative forcing and climate feedbacks determines the role aerosols play in the maintenance of the current radiation balance. Occasionally, natural or anthropogenic events create locally severe aerosol loads that could lead to large climatic perturbations. One example is the springtime Arctic haze that has been studied for several years. Most atmospheric aerosols of anthropogenic origin are sulfates or smoke, which have residence times in the troposphere of about a week; in contrast greenhouse gases have lifetimes of decades to centuries. A reduction in the emission of sulfur-containing gases, which are the primary precursors of sulfate aerosols, would result in an immediate concomitant decrease in the negative shortwave radiative forcing of the climate system. © 1993, Academic Press Inc."
"7006561590;7409871783;35468030800;","New parameterizations and sensitivities for simple climate models",1993,"10.1029/92JD02666","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027387433&doi=10.1029%2f92JD02666&partnerID=40&md5=6b33713d27ba60289479d11dba87d804","This paper presents a reexamination of the Earth radiation budget parameterization of energy balance climate models in light of data collected over the last 12 years. The study consists of three parts: 1) an examination of the infrared terrestrial radiation to space and its relationship to the surface temperature field on time scales from 1 month to 10 years; 2) an examination of the albedo of the Earth with special attention to the seasonal cycle of snow and clouds; 3) solutions for the seasonal cycle using the new parameterizations with special attention to changes in sensitivity. While the infrared parameterization is not dramatically different from that used in the past, the albedo in the new data suggest that a stronger latitude dependence be employed. -from Authors"
"57045694100;57045579400;7402830236;","Aqueous Greenhouse Species in Clouds, Fogs, and Aerosols",1993,"10.1021/es00049a029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027788154&doi=10.1021%2fes00049a029&partnerID=40&md5=4763f7b8d61a93731f6baefbe539f268","Greenhouse effects from fossil fuel combustion leading to increased concentrations of primary and secondary greenhouse gases (e.g., CO2, ozone, etc.) have received considerable attention. More recently, it has been suggested that clouds, aerosols, and fogs can play opposing roles in climate forcing by scattering or absorbing incoming solar radiation as well as by absorbing long-wave radiation as it escapes into space. The total effect on the radiation balance depends on the relative magnitude of these opposing forces, which in turn will depend on the composition of the aqueous phase. This work describes the measurement of water-soluble infrared absorbers which can contribute to the long-wave radiative forcing of clouds, fogs, and aerosols. Aqueous species which have been characterized include sulfate, nitrate, formate, acetate, oxalate, phenol, p-nitrophenol, ammonium, bicarbonate, formaldehyde, methanol, and ethanol. Infrared absorption band positions and band strengths have been determined, and their relative effects on radiative forcing are discussed. © 1993, American Chemical Society. All rights reserved."
"6602157963;7005428977;","A method of comparison of two close batches data: Application to analysis of fog formation causes",1993,"10.1029/93GL00075","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027796976&doi=10.1029%2f93GL00075&partnerID=40&md5=6bb44bf84c058d2d64d94455bc757e81","Given suitable conditions of air temperature and humidity, the density of a fog and its microphysical properties depend mainly on the availability of cloud condensation nuclei (CCN) and their nature. Fogs become particularly dense near certain industrial plants because of high concentration of hygroscopic combustion particles in the air. Their role in dense fog formation is estimated by comparing the local climates and CCN concentrations at two similar sites, the first being more subject to air pollution and dense fogs than the second. Orthogonal regression is applied to three meteorological variables (air temperature, relative humidity, wind speed) and CCN concentration. As we compare very close variables, bootstrap provides precise confidence intervals independent of Gaussian assumptions. Two sites are compared: they are located in the Meuse valley (Belgium) at a distance of about 15 km. We found that the local climate of the polluted site is not only colder and wetter but also richer in CCN that the control site. These results suggest interactions of natural and anthropogenic causes in dense fog formation at industrial site. This method is useful in various domains of geophysics when correlated time series have to be compared. Copyright 1993 by the American Geophysical Union."
"7006592026;7005696178;7101846835;6506512484;","Development of a second-generation regional climate model (RegCM2). Part II: convective processes and assimilation of lateral boundary conditions",1993,"10.1175/1520-0493(1993)121<2814:DOASGR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027796712&doi=10.1175%2f1520-0493%281993%29121%3c2814%3aDOASGR%3e2.0.CO%3b2&partnerID=40&md5=d27f25487421ffbf87195ec8c6d8d7f8","We first discuss the inclusion in the model of the cumulus cloud scheme developed by Grell (referred to as GCC). The sensitivity of summertime and wintertime results to different closures and parameter settings in the GCC scheme are examined in model simulations conducted over Europe. While wintertime precipitation is found to vary only slightly between the experiments, a wide range of results is found in the summer runs. The GCC scheme produces more rain than a Kuo-type scheme, responds strongly to variations in the surface energy and moisture fluxes, and performs best when used in conjunction with the most advanced physics processes of RegCM2. Modifications to the standard model relaxation boundary condition procedure, which allow smoother assimilation of driving lateral boundary data, are also discussed. -from Authors"
"7006904374;7003684963;","Local versus nonlocal boundary-layer diffusion in a global climate model",1993,"10.1175/1520-0442(1993)006<1825:LVNBLD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027881517&doi=10.1175%2f1520-0442%281993%29006%3c1825%3aLVNBLD%3e2.0.CO%3b2&partnerID=40&md5=c25b324199ef8006e28326df6cb8c809","The global model is an updated version of the NCAR Community Climate Model (CCM2). The local diffusion scheme uses an eddy diffusivity determined independently at each point in the vertical, based on local vertical gradients of wind and virtual potential temperature, similar to the usual approach in global atmospheric models. The nonlocal scheme determines an eddy-diffusivity profile based on a diagnosed boundary-layer height and a turbulent velocity scale. It also incorporates nonlocal (vertical) transport effects for heat and moisture. The nonlocal scheme transports moisture away from the surface more rapidly than the local scheme, and deposits the moisture at higher levels. The local scheme tends to saturate the lowest model levels unrealistically, which typically leads to clouds too low in the atmosphere. The nonlocal scheme has been chosen for CCM2 because of its more comprehensive representation of the physics of boundary-layer transport in dry convective conditions. -from Authors"
"6603928917;7004239652;8225183400;7005455874;7003899619;7006113978;7406228987;8684241900;","1992 Brings return to moderate global temperatures",1993,"10.1029/93EO00372","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027843922&doi=10.1029%2f93EO00372&partnerID=40&md5=1ea0fff9fc0ad3968cc25e2159242bb2","Natural events, such as the Mt. Pinatubo eruption in the Philippines and the El Niño/Southern Oscillation (ENSO) episode in the tropical Pacific Ocean, had major impacts on the global climate in 1992. These phenomena were associated with a return to more moderate global temperatures during 1992 after several years of record or near‐record high temperatures. During the first part of the year, the 1991–1992 ENSO episode contributed to above normal temperatures in the Northern Hemisphere, while cooling during the latter part of the year was associated with the aerosol cloud produced by the June 1991 eruption of Mt. Pinatubo. By the spring of 1992, the stratospheric aerosol cloud had extended from the tropics well into both hemispheres. In this report, global surface temperature anomalies are defined as departures from the 1961–1990 base period means. As the aerosol cloud spread throughout the Northern Hemisphere during a time of increasing solar radiation, the surface temperature anomalies responded by becoming less positive over much of the hemisphere. This relative cooling helped to make 1992 the coolest year since 1986. Temperatures also were dramatically cooler throughout the troposphere. ©1993. American Geophysical Union. All Rights Reserved."
"57213075999;","The greenhouse complex",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799102&partnerID=40&md5=cd23ac682176b6ae7eae55a8dc4cc1c4","Concern regarding the climatological consequences of human-released, heat-retaining greenhouse gases has become widespread only in recent years, in spite of centuries-long accumulation of such gases in the troposphere. And yet despite intense climatological interest now being given to these gases, the complex interaction among the gases which comprise the greenhouse system defies simple or even sophisticated attempts to predict their collective impact on climate in the face of human-initiated increases. This paper reviews this greenhouse phenomenon along with the properties of the greenhouse gases CO2, CH4, N2O, CFCs, water vapour, and clouds. -Author"
"7004288767;","Tropospheric ozone and climate change",1993,"10.1080/1073161X.1993.10467207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027676212&doi=10.1080%2f1073161X.1993.10467207&partnerID=40&md5=1bead834862c6f49c3b63d60364b17b4","Considerable attention has been paid in recent years to photochemical smog pollution close to the earth's surface and to stratospheric ozone depletion. There is reason to suspect that the next round of scientific concern will be devoted to the perturbations in the “free troposphere.” Tropospheric ozone has been building up in many regions of the northern hemisphere. Ozone changes in the upper troposphere will exert a considerable impact on global warming. This could affect moisture levels, cloud amount and distribution, precipitation, and atmospheric dynamics on different scales. This paper analyzes: (1) the physical and chemical processes contributing to changes in tropospheric ozone concentration; (2) the observational evidence of previous ozone change; and (3) results drawn from computer modelling of past and future radiative forcing caused by rising ozone concentrations in the upper troposphere. The solar and longwave radiative model developed by Wang et al. (1991) was used for calculating the change in radiative forcing to the troposphere-surface system that can be ascribed to changing concentrations in ozone and other greenhouse gases. Nitric oxide emission from aircraft are a prime suspect for the observed increases in upper tropospheric ozone. The inference can be drawn that a radiative forcing of 0.2 to 0.35 Wm-2will result from a doubling of aircraft emissions over the next two decades. This will amount to 10 to 25 percent of the radiative forcing attributable to CO2alone for the same period. The effect of doubling aircraft emissions will increase as stratospheric ozone concentrations recover from the recent buildup of harmful chlorofluorocarbons. A large fraction of the radiative forcing that occurred during the 1970 to 1990 period can be attributed to increases in tropospheric ozone as opposed to increases in other greenhouse gases. © Taylor and Francis Group, LLC."
"7401559815;7006329926;7202772927;","A preliminary study of the tropical water cycle and its sensitivity to surface warming",1993,"10.1175/1520-0477(1993)074<1313:APSOTT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027881086&doi=10.1175%2f1520-0477%281993%29074%3c1313%3aAPSOTT%3e2.0.CO%3b2&partnerID=40&md5=d162580536e88b604dd77b9c9704fde1","This paper presents the preliminary findings of an investigation of the water budget of tropical cumulus convection using the Goddard Cumulus Ensemble Model (GCEM). Results of an experiment designed to obtain a ""fingerprint' in the tropical hydrologic cycle in response to surface warming are also presented. The ensemble mean water budget shows that the distribution of water vapor and cloud water in the tropical atmosphere is maintained as a result of a balance between moisture convergence (including cloud scale and large scale) and condensation and reevaporation by various microphysical species within the cumulus clusters. Under radiative convective equilibrium conditions, 66% of the precipitation reaching the ground comes from the convective region and 34% from the stratiform region. In a climate with above-normal sea surface temperature but fixed large-scale vertical velocity, tropical convection is enhanced with more abundant moisture sources. -from Authors"
"56157800800;","The effects of reduced land fraction and solar forcing on the general circulation: results from the NCAR CCM",1993,"10.1016/0921-8181(93)90004-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027880382&doi=10.1016%2f0921-8181%2893%2990004-8&partnerID=40&md5=45f5301b6e7bfd5d030652837cded94b","Land fraction and the solar energy at the top of the atmosphere (solar constant) may have been significantly lower early in Earth's history. It is likely that both of these factors played some important role in the climate of the early earth. The climate changes associated with a global ocean(i.e. no continents) and reduced solar constant are examined with a general circulation model and compared with the present-day climate simulation. The general circulation model used in the study is the NCAR CCM with a swamp ocean surface. First, all land points are removed in the model and then the solar constant is reduced by 10% for this global ocean case. Results indicate that a 4 K increase in air temperature occurs with global ocean simulation compared to the control. When solar constant is reduced by 10% under global ocean conditions a 23 K decrease in air temperature is noted. The global ocean warms much of the troposphere and stratosphere, while a reduction in the solar constant cools the troposphere and stratosphere. The largest cooling occurs near the surface with the lower solar constant. Global mean values of evaporation, water vapor amounts, absorbed solar radiation and the downward longwave radiation are increased under global ocean conditions, while all are reduced when the solar constant is lowered. The global ocean simulation produces sea ice only in the highest latitudes. A frozen planet does not occur when the solar constant is reduced-rather, the ice line settles near 30° of latitude. It is near this latitude that transient eddies transport large amounts of sensible heat across the ice line acting as a negative feedback under lower solar constant conditions keeping sea ice from migrating to even lower latitudes. Clouds, under lower solar forcing, also act as a negative feedback because they are reduced in higher latitudes with colder atmospheric temperatures allowing additional solar radiation to reach the surface. The overall effect of clouds in the global ocean is to act as a positive feedback because they are slightly reduced thereby allowing additional solar radiation to reach the surface and increase the warming caused by the removal of land. The relevance of the results to the ""Faint-Young Sun Paradox"" indicates that reduced land fraction and solar forcing affect dynamics, heat transport, and clouds. Therefore the associated feedbacks should be taken into account in order to understand their roles in resolving the ""Faint-Young Sun Paradox"". © 1993."
"35985515200;7102018821;55732462400;","An assessment of the differential inversion method for remote sounding of temperatures",1993,"10.1175/1520-0450(1993)032<1108:AAOTDI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027798308&doi=10.1175%2f1520-0450%281993%29032%3c1108%3aAAOTDI%3e2.0.CO%3b2&partnerID=40&md5=3e49737362d0022d98f051eb52c01073","Explores the applicability of the differential inversion (DI) method to temperature retrievals in both clear and cloudy atmospheres using real satellite data. The main theme of the DI is that the local Planck intensity can be exactly expressed by a linear combination of the derivatives of radiances in the logarithmic pressure coordinate. The inversion coefficients are obtained by fitting the weighting function to a generalized form. The higher-order derivatives of radiances are determined from polynomial fittings. The satellite dataset used in this work contains collocated brightness temperatures and radiosonde data that have been collected during the period of Baseline Upper Atmospheric Network (BUAN) experiments. Results indicate first that the DI can achieve acceptable performance without first-guess or error covariance matrices; second, that the proposed multispectral cloud-removal method is also capable of generating reasonable cloud-removed clear radiances; and finally that the DI can be used as a tool to obtain first guesses in the current operational method and to perform large-volume temperature retrievals for climate studies. -from Authors"
"35556949600;7403128512;57189878212;55906046800;","Southwest Pacific temperatures: Diurnal and seasonal trends",1993,"10.1029/93GL01113","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027838576&doi=10.1029%2f93GL01113&partnerID=40&md5=2cd6e86f179190f2c889101d959feae7","Temperature trends are presented for a large part of the southwest Pacific. The trends differ from those documented for Northern Hemisphere land areas, where warming has occurred mainly through increases in minimum temperature. The New Zealand patterns are derived from recently completed analyses of monthly and annual mean maximum and minimum surface temperature records for a newly homogenised historical climate data series for New Zealand and outlying islands. They indicate that the warming in the New Zealand region over the past five decades can be attributed to increases in both mean maximum (mostly daytime) and mean minimum (mostly night time) temperature. All seasons show a temperature increase, with the largest occurring in summer (DJF). Northern Hemisphere evidence suggests that changes in cloud cover and the presence of sulfate aerosols plays a direct role. The present results imply that, while the observed warming in a large portion of the Northern Hemisphere landmass may be significantly affected by both these factors, sulfate aerosol effects may be less important in the Southern Hemisphere. Copyright 1993 by the American Geophysical Union."
"7004731743;7005710817;","Sensitivity of simulated dew duration to meteorological variations in different climatic regions of California",1993,"10.1016/0168-1923(93)90073-Q","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027333336&doi=10.1016%2f0168-1923%2893%2990073-Q&partnerID=40&md5=aa80d1c6cb9b56b8576d7c8ee6d8cefb","A previously verified and validated model was used in combination with hourly weather data to simulate the frequency and duration of dew occurrence over one growing season (April-October) at four sites under coastal fogbelt, coastal valley, and interior valley climates in California. Simulation results indicated similar values of dew occurrence (78-93% of the days) and mean dew duration (8.7-9.3 h day-1 or 9.7-11.2 h per dew event) at the coastal stations, despite high day-to-day variability and steep climatic gradients between these sites. Dew periods at the interior valley site, where occurrence of dew was predicted on only 23% of the days, were much shorter (mean 0.9 h day-1 or 3.7 h per dew event). The data displayed moderate seasonal trends, with the longest dew periods occurring in fall at the coastal stations and in spring at the interior valley station. Simulated dew durations showed favorable agreement with measured dew durations in an independent validation study. Based on real-system weather data and simulated dew data, sensitivity analyses were performed to compare the effects of temperature, atmospheric humidity (vapor pressure), cloud cover, and wind speed on dew duration at the four test sites. The results showed simulated dew durations most sensitive to changes in humidity and cloud cover at the coastal sites and to humidity and wind speed at the interior valley site. Relative sensitivity values were generally highest during the summer months (June-August). Spatial variations (i.e. differences between locations) and seasonal variations (i.e. differences between different seasons at the same site) of relative sensitivity values had approximately the same magnitude. © 1993."
"7202429440;7005254328;7201432984;7006839912;6505868969;7004285242;","Dimethylsulfide/cloud condensation nuclei/climate system: relevant size-resolved measurements of the chemical and physical properties of atmospheric aerosol particles",1993,"10.1029/93jd00467","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799846&doi=10.1029%2f93jd00467&partnerID=40&md5=33b5d166e4935c3f9319417bafc47272","Comparisons between particle mass and surface area indicate that non-sea-salt sulfate, methanesulfonate, and ammonium were not involved in new particle production on the 12- to 24-hour time scale of the measurements. Instead, high levels of available particle surface area resulted in the condensation of the gas phase precursors onto existing aerosol. A doubling of non-sea-salt sulfate, methanesulfonate, and ammonium mass corresponded to a 40% to 50% increase in number in the accumulation mode size range. Likewise, a doubling of the non-sea-salt sulfate mass corresponded to a 40% increase in the CCN number concentration. As methanesulfonate made up a very small fraction of the soluble particulate mass, no correlations were found between methanesulfonate mass and CCN number. In a seperate experiment, the percent of methanesulfonate in the supermicrometer particle size fraction was greater in these samples than in those collected over coastal waters of the northeastern Pacific. In both regions the non-sea-salt sulfate mass size distributions were bimodal, while ammonium was found to be concentrated in larger accumulation mode particles. -from Authors"
"7003904922;7003877787;","Correlations of atmospheric dynamics with solar activity evidence for a connection via the solar wind, atmospheric electricity, and cloud microphysics",1993,"10.1029/93jd00627","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799826&doi=10.1029%2f93jd00627&partnerID=40&md5=326c22e7e6a8b8fe0c0cb670da7fdca8","We show that the aliasing criticism is inadequate because the real quasi-biennial oscillation departs from an ideal sine wave in a way that reduces aliasing effects to insignificant levels. The nonuniqueness of identification of the 11-year solar cycle as the period of the arctic forcing for the Arctic winter stratospheric temperatures is a problem only for the short 33-year record of polar temperatures; in much longer time series of unstratified climate data the periods of 11 and 22 years are prominent. Highly unique signatures of solar wind forcing of tropospheric dynamics exist on the day-to-day time scale via two independent inputs to atmospheric electricity. These are (1) through changes in tropospheric ion production as a result of solar wind modulation of galactic cosmic rays and (2) through changes in the potential difference between the polar ionospheres and the surface, forced by the solar wind By component. The product of the cosmic ray flux and the ionospheric potential determines the vertical air-earth electrical current. -from Authors"
"7401844779;","Pinatubo and pre-Pinatubo optical-depth spectra: Mauna Loa measurements, comparisons, inferred particle size distributions, radiative effects, and relationship to lidar data",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027798801&partnerID=40&md5=f573afdb5106d6ef851abe16f2b9d2b9","The Ames airborne tracking sunphotometer was operated at the National Oceanic and Atmospheric Administration (NOAA) Mauna Loa Observatory (MLO) in 1991 and 1992 along with the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) automated tracking sunphotometer and lidar. June 1991 measurements provided calibrations, optical-depth spectra, and intercomparisons under relatively clean conditions; later measurements provided spectra and comparisons for the Pinatubo cloud plus calibration checks. June 1991 results are similar to previous MLO springtime measurements, with midvisible particle optical depth τp(λ = 0.526 μm) at the near-background level of 0.012 ± 0.006 and no significant wavelength dependence in the measured range (λ = 0.38 to 1.06 μm). The arrival of the Pinatubo cloud in July 1991 increased midvisible particle optical depth by more than an order of magnitude and changed the spectral shape of τp(λ) to an approximate power law with an exponent of about -1.4. Heating rates in the Pinatubo layer over MLO are 0.55 ± 0.13 and 0.41 ± 0.14 K d-1 for September 1991 and July 1992, respectively. -from Authors"
"7004129006;7003292889;","A global view of large-scale precipitation variability",1993,"10.1175/1520-0442(1993)006<1495:AGVOLS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799632&doi=10.1175%2f1520-0442%281993%29006%3c1495%3aAGVOLS%3e2.0.CO%3b2&partnerID=40&md5=8c48d8dc46594f0a5f71d79e69fec8ee","Rainfall in the deep tropics is particularly important as a forcing mechanism for the atmosphere's large-scale circulation and climate. Analysis of systematic space-based observations and surface marine data over the past three decades has vastly improved our understanding of tropical convective regimes and their relationship to sea surface temperature field and the general circulation of the tropics are reviewed. The hierarchal nature of tropical precipitation variability on time/space scales ranging from synoptic cloud clusters through the intraseasonal Madden-Julian Oscillation to multiyear El Nino-Southern Oscillation cycle is discussed. Links between tropical convection and extratropical precipitation on time scales ranging from synoptic to multiyear are examined, with emphasis on conditions over the North Pacific-North American sector during winter. -from Authors"
"7003765770;","A hydrological cycle model for global research",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027705711&partnerID=40&md5=564a539f2b81b25a9705a1fc9ef7ac84","A simple parametrization model of global hydrologic cycle, which can be used to assess global consequences of anthropogenic impacts, has been developed. The model calculates the vertical profile and space distribution of atmospheric water vapor, its advective and eddy transport, cloud amount at three levels and rainfall, evaporation and evapotranspiration, snow storage and snowmelt, runoff and integral soil moisture. The verification results have been shown for the model and experiments on the investigation of its sensitivty to climatic impacts and to model parameters. The possibility has been discussed of increasing the accuracy of forecasting the anthropogenic impact on hydrological regime due to the use of global observation data on the assumption that mean climate is stable in constant external conditions. -Journal summary"
"7004926126;7005594741;7003339760;","Assessment of the role of zooplankton in the cycling of DMSP and DMS in the water column during EUMELI-4 (France-JGOFS)",1993,"10.1007/978-94-017-1261-3_2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027846216&doi=10.1007%2f978-94-017-1261-3_2&partnerID=40&md5=c19dfb44999577e69ad225197f5a4d66","DMS (dimethyl sulfide) plays an important role in the marine environment because it contributes to the acidity of precipitations and may be to marine cloud formation and climate regulation. Since DMS appears to arise primarily from dimethylsulfoniopropionate (DMSP), it is important to understand the processes controlling the cycling of DMSP in the oceanic upper water column. During the fourth EUMELI (France-JGOFS) cruise (May-June 1992) in the tropical northeastern Atlantic Ocean, DMSP analyses on sediment trap material were performed to assess the sink of DMSP by particulate sedimentation and the involvement of zooplankton. From these data it is evident that zooplankton nycthemeral migration controls the vertical flux of particulate DMSP independently of the intensity of the source of particulate matter, of the particulate DMSP content of upper water layers and of the zooplankton communities. -from Authors"
"7004240126;6603889543;6602820825;7202448716;","Forest climatology near the tree line in Hawai'i",1993,"10.1016/0168-1923(93)90068-S","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027333333&doi=10.1016%2f0168-1923%2893%2990068-S&partnerID=40&md5=2ed7094d610a49fe004a2803c2e51126","One year of climatological measurements in a high elevation forest on the island of Hawai'i are analyzed to partially characterize the habitat of the palila bird, an endangered Hawaiian honeycreeper. At 2600 m, the site lies below the tree line, above the usual level of the trade wind inversion, and is strongly influenced by the diurnal thermal wind regime. The interaction of inversion, thermal circulation, and surface climate is documented for solar radiation, air and soil temperatures, humidity, wind direction and speed, rainfall, cloud water collection, and canopy throughfall. A comparison of air temperature, humidity, and soil temperature measurements between an open air site and beneath the canopy of an isolated mamane tree showed little difference, except that extremes in soil temperature were much greater in the open. Tree canopy throughfall exceeded open area rainfall during fog dominated precipitation events. © 1993."
"7202295135;7005110573;7202432336;7005363686;7006021743;7006677714;6602920608;","Terrestrial ecosystem production: A process model based on global satellite and surface data",1993,"10.1029/93GB02725","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027836106&doi=10.1029%2f93GB02725&partnerID=40&md5=acf08d3086d1038b17d6ffd465e2cb40","This paper presents a modeling approach aimed at seasonal resolution of global climatic and edaphic controls on patterns of terrestrial ecosystem production and soil microbial respiration. We use satellite imagery (Advanced Very High Resolution Radiometer and International Satellite Cloud Climatology Project solar radiation), along with historical climate (monthly temperature and precipitation) and soil attributes (texture, C and N contents) from global (1°) data sets as model inputs. The Carnegie‐Ames‐Stanford approach (CASA) Biosphere model runs on a monthly time interval to simulate seasonal patterns in net plant carbon fixation, biomass and nutrient allocation, litterfall, soil nitrogen mineralization, and microbial CO2 production. The model estimate of global terrestrial net primary production is 48 Pg C yr−1 with a maximum light use efficiency of 0.39 g C MJ−1PAR. Over 70% of terrestrial net production takes place between 30°N and 30°S latitude. Steady state pools of standing litter represent global storage of around 174 Pg C (94 and 80 Pg C in nonwoody and woody pools, respectively), whereas the pool of soil C in the top 0.3 m that is turning over on decadal time scales comprises 300 Pg C. Seasonal variations in atmospheric CO2 concentrations from three stations in the Geophysical Monitoring for Climate Change Flask Sampling Network correlate significantly with estimated net ecosystem production values averaged over 50°–80° N, 10°–30° N, and 0°–10° N. Copyright 1993 by the American Geophysical Union."
"7410187941;36097494200;","A synoptic climatological analysis of air quality in the Grand Canyon National Park",1993,"10.1016/0960-1686(93)90189-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027577417&doi=10.1016%2f0960-1686%2893%2990189-6&partnerID=40&md5=917d63abdefdc49103f9e29b5634d33d","Daily air quality variations within the Grand Canyon National Park, AZ are related to a regional synoptic climatology. The climatology is developed using upper air data from 21 stations throughout the western U.S.A. and Mexico from 1979 to 1988. Thirteen synoptic situations are identified which represent days with distinct and recurring meteorological conditions throughout the region. Daily particulate concentrations and scattering coefficient readings from Hopi Point, on the south rim of the Grand Canyon, are related to the daily synoptic climatology. Three synoptic situations are associated with poor air quality. Summer monsoon days have poor air quality because of high humidity and cloud cover. On continental high days, a slow-moving anticyclone is located near the Great Basin and local pollutants are trapped within the boundary layer in this poorly ventilated air mass. The situation with the worst air quality-Rockies Ridge-has strong southwesterly winds throughout the troposphere, suggesting that regional haze is advected from southern California into the Grand Canyon area. Good air quality occurs (1) during zonal flow situations when the jet stream is strong; (2) when cold, dry air masses are present; (3) during dry and generally clear days in the summer. This research demonstrates the utility of analysing air quality problems from a synoptic climatological framework. © 1993."
"57206225739;","Snow and ice applications of AVHRR in polar regions: report of a workshop held in Boulder, Colorado, 20 May 1992",1993,"10.3189/s0260305500012544","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027808131&doi=10.3189%2fs0260305500012544&partnerID=40&md5=88cb8410dd81bdb0c506d60fb5b2a3a1","At the third symposium on Remote Sensing of Snow and Ice, a total of 21 papers was presented on snow and ice applications of Advanced Very High Resolution Radiometer (AVHRR) satellite data in polar regions. Also during this meeting a NASA sponsored Workshop was held to review the status of polar surface measurements from AVHRR. The following summarizes the ideas and recommendations from the workshop, and the conclusions of relevant papers given during the regular symposium sessions. The seven topics discussed include cloud masking, ice surface temperature, narrow-band albedo, ice concentration, lead statistics, sea-ice motion and ice-sheet studies with specifics on applications, algorithms and accuracy, folllowing recommendations for future improvements. However, progress is needed to reduce the uncertainty of the retrieved parameters for all the topics to make this data set useful for direct climate applications such as heat balance studies and others. -from Authors"
"57201806565;","The application of a continental-scale radar database to hydrological process parametrization within Atmospheric General Circulation Models",1993,"10.1016/0022-1694(93)90015-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027334369&doi=10.1016%2f0022-1694%2893%2990015-2&partnerID=40&md5=35080c0571be5b3e56e2dbb6161db208","Atmospheric General Circulation Models (GCMs) used for climate research operate on a resolution of about 250 km and provide outputs averaged on a daily and monthly basis. The formation and evaporation of precipitation within cloud systems produces large latent heating effects. These effects constitute an important source of uncertainty in climate and, to a lesser extent, weather-forecasting models. There remains a large impact from this uncertainty on the performance of these models, produced by inadequate parametrization on scales of around 100-300 km. Likewise, variations of soil properties and of infiltration are not adequately defined at these scales, and therefore it is necessary to parametrize these processes. Unfortunately, the relationship between rainfall and runoff is highly non-linear, and the rate of infiltration will vary throughout a catchment area, making parametrization very difficult. Since 1986 the Commission of the European Communities (CEC) COST-73 Weather Radar Networking Project has encouraged the exchange of weather radar data between the countries of Europe. As part of the work undertaken in this project, instantaneous radar composite images over NW Europe were generated every hour with a grid resolution of about 5 km. Data from radars located in the UK, Ireland, France, The Netherlands, Switzerland, and Belgium have been used. In the paper we discuss the nature of this database, and consider its reliability for estimating daily and monthly precipitation. We explore how this database might be used to develop a more effective parametrization scheme for surface hydrological processes within GCMs. Finally, the adequacy of such a database for continental-scale hydrological studies is assessed. It is noted that there is considerable scope for further studies of this type using radar data from most countries in both Western and Eastern Europe. © 1993."
"56157800800;","A general circulation model study of the effects of faster rotation rate, enhanced CO2 concentration, and reduced solar forcing: implications for the faint young Sun paradox",1993,"10.1029/93jd02056","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027842418&doi=10.1029%2f93jd02056&partnerID=40&md5=43f0dc14def7fed373d7af557bed0ac7","The control simulation of this study has a solar constant reduced by 10% the present amount, zero land fraction using a swamp ocean surface, CO2 concentrations of 330 ppmv, present-day rotation rate, and is integrated under mean diurnal and seasonal solar forcing. Four sensitivity tests are performed under zero land fraction and reduced solar constant conditions: 1) increased rotation rate, 2) 8 times present CO2, 3) a combination of 1 and 2, and 4) 3 with a 15% reduction in the solar constant. Results indicate the following changes in the global mean sea surface temperatures (SSTs) compared to the control simulation: 1) +6.6 K, 2) +12 K, 3) +18.5 K, and 4) +6.6 K relative to the control's global mean temperature of 264.7 K. Sea ice is confined to higher latitudes in each experiment compared to the control, with ice-free areas equatorward of the subtropics. The warm SSTs are associated with a 20% reduction in clouds for the rotation rate experiments and higher CO2 concentrations in the other experiments. -from Author"
"7006432040;7004064829;16518328100;","Habitable Zones around Main Sequence Stars",1993,"10.1006/icar.1993.1010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027538885&doi=10.1006%2ficar.1993.1010&partnerID=40&md5=655b57dd7d1e2ca54452cca3e6853aa7","A one-dimensional climate model is used to estimate the width of the habitable zone (HZ) around our Sun and around other main sequence stars. Our basic premise is that we are dealing with Earth-like planets with CO2/H2O/N2 atmospheres and that habitability requires the presence of liquid water on the planet's surface. The inner edge of the HZ is determined in our model by loss of water via photolysis and hydrogen escape. The outer edge of the HZ is determined by the formation of CO2 clouds, which cool a planet's surface by increasing its albedo and by lowering the convective lapse rate. Conservative estimates for these distances in our own Solar System are 0.95 and 1.37 AU, respectively; the actual width of the present HZ could be much greater. Between these two limits, climate stability is ensured by a feedback mechanism in which atmospheric CO2 concentrations vary inversely with planetary surface temperature. The width of the HZ is slightly greater for planets that are larger than Earth and for planets which have higher N2 partial pressures. The HZ evolves outward in time because the Sun increases in luminosity as it ages. A conservative estimate for the width of the 4.6-Gyr continuously habitable zone (CHZ) is 0.95 to 1.15 AU. Stars later than F0 have main sequence lifetimes exceeding 2 Gyr and, so, are also potential candidates for harboring habitable planets. The HZ around an F star is larger and occurs farther out than for our Sun; the HZ around K and M stars is smaller and occurs farther in. Nevertheless, the widths of all of these HZs are approximately the same if distance is expressed on a logarithmic scale. A log distance scale is probably the appropriate scale for this problem because the planets in our own Solar System are spaced logarithmically and because the distance at which another star would be expected to form planets should be related to the star's mass. The width of the CHZ around other stars depends on the time that a planet is required to remain habitable and on whether a planet that is initially frozen can be thawed by modest increases in stellar luminosity. For a specified period of habitability, CHZs around K and M stars are wider (in log distance) than for our Sun because these stars evolve more slowly. Planets orbiting late K stars and M stars may not be habitable, however, because they can become trapped in synchronous rotation as a consequence of tidal damping. F stars have narrower (log distance) CHZ's than our Sun because they evolve more rapidly. Our results suggest that mid-to-early K stars should be considered along with G stars as optimal candidates in the search for extraterrestrial life. © 1993 by Academic Press, Inc."
"6602653884;","Data-sparse estimation of lake evaporation, using a simplified Penman equation",1993,"10.1016/0168-1923(93)90031-C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027836722&doi=10.1016%2f0168-1923%2893%2990031-C&partnerID=40&md5=04d62bd1d3a014b7726257fa2c9ab884","At many places the only reliable climate measurements available are those of daily minimum screen temperature, daily maximum, rainfall and windspeed. However, even the temperatures alone are sufficient for estimating monthly mean lake evaporation E0, using the following simplified version of Penman's formula: E0=(0.015+0.00042T+10-6z)[0.8RS-40+2.5Fu(T-Td)](mm day-1), where T is the daily mean temperature (i.e. the average of the extremes), z is the elevation (m), Rs is the solar irradiance of the lake's surface, F stands for (1.0 - 8.7 × 10-5 z), u is the windspeed at 2 m, and Td is the dewpoint temperature. Two new methods of estimating Rs are described, the more accurate being based on rainfall data, as proxy for the cloud which reduces extraterrestrial radiation. Td can be estimated from the daily extreme temperatures. The windspeed can be gauged from measurements nearby or at other times, since accuracy is not important. Errors of estimating monthly mean evaporation are consequently around 0.3 mm day-1 at Copenhagen. For annual evaporation at three lakes in the USA, estimates differ from measurements by 0.1, 0.4 and 0.1 mm day-1, respectively, but the errors of the measurements are uncertain. Estimates for a reservoir in Western Australia are closer to measurements by the Bowen-ratio method, than are water-balance measurements. On average, monthly estimates and Bowen-ratio measurements there differ by about 0.8 mm day-1, whilst averages over 2 years differ by 0.3 mm day-1. The annual range of monthly mean temperatures at a place is proportional to the latitude and to d0.2, where d (km) is the distance downwind of the ocean . © 1993."
"55567251100;25938869100;57209514356;","A 173 year stable isotope record from a tropical south pacific coral 0",1993,"10.1016/S0277-3791(05)80005-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027838606&doi=10.1016%2fS0277-3791%2805%2980005-8&partnerID=40&md5=16ae87df5e20f7820c9a36c2c7b96124","We have generated a 173 year-long time series (A.D. 1806 to 1979) of changes in the δ18O and δ13C composition of a coral head (Platygyra lamellina) to investigate environmental change in the climatologically sensitive region of the tropical South Pacific. Little is known about decadal- and centennial-scale climate change at sea level in this region. Our coral is from near the south coast of Espiritu Santo Island (15°S, 167°E), Republic of Vanuatu. The stable isotope record from this coral is consistent with meteorological and oceanographic records during the period of overlap in the records (1964-1978): δ18O values positively correlate with SST (r=0.77) and δ13C values are highly coherent with rainfall (r=0.82) at the annual cycle. These relations suggest that the δ18O signal in this coral is a function of variations in SST and rainfall-induced changes in SSS, whereas the δ13C signal may be related to rainfall and cloud cover modulation of photosynthesis in the coral. δ18O and δ13C values are positively correlated over the entire length of the record (r=0.65), a relation that is even stronger between 1806 and 1866 (r=0.81), i.e. prior to the time of possible anthropogenic influence on the δ13C record. Because of the positive correlation between temperature and rainfall in this region, we interpret the long-term record of δ18O in terms of joint variations of these two variables. The most significant cool/dry excursion in the Santo record occurs during the nineteenth century (∼1832-1866) and ends abruptly in 1866 with a change to modern values. Superimposed on this pattern is a slight (0.2%.), cooling/drying toward the end of the twentieth century. Cross-spectral analysis of the δ18O and δ13C records indicates a strong concentration of variance at the quasi-biennial (∼2 years) and El Nino/Southern Oscillation (ENSO) (∼4-5 years) frequency bands, in addition to a ∼15 year peak found also in global temperature records. Cross-spectral analysis of coral isotope records from Santo and the Philippine Sea, indicate a concentration of variance at ENSO (∼4-5 years) frequency bands. However, comparison of the Santo coral isotope record with high-latitude northern hemisphere temperature records indicates that the major cool/dry excursion in the Santo record (∼1832-1866) is not seen in the northern hemisphere record. If verified in other tropical South Pacific coral records, the results have implications concerning the global scale of cooling for Little Ice Age events. © 1994 Elsevier Science Ltd."
"7102798096;7005022197;","The first Greenland ice core record of methanesulfonate and sulfate over a full glacial cycle",1993,"10.1029/93GL00910","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027799385&doi=10.1029%2f93GL00910&partnerID=40&md5=027323655b855e287fdf2ede3d09d140","Methanesulfonate (MSA) in ice cores has attracted attention as a possible tracer of past oceanic emissions of dimethylsulfide (DMS). After sulfate MSA is the second most prevalent aerosol oxidation product of DMS, but in contrast to sulfate, DMS oxidation is the only known source of MSA. The hypothesis by Charlson et al., [1987] of a climate feedback mechanism with sulfur emissions from marine phytoplankton influencing the cloud albedo adds to the interest in establishing long records of MSA and non‐seasalt sulfate spanning large climatic changes. Records of MSA and non‐seasalt sulfate covering time periods from a few years to thousands of year have been extracted from antarctic ice cores [Ivey et al., 1986; Saigne and Legrand, 1987; Legrand and Feniet‐Saigne, 1991; Mulvaney et al., 1992] but only the record from the Vostok ice core [Legrand et al., 1991] covers a full glacial cycle. The concentrations of MSA and non‐seasalt sulfate in Antarctica have been found to increase under glacial conditions. Here we present the first Northern Hemisphere record of MSA, and the first continuous record of non‐seasalt sulfate, both extracted from the Renland ice core, East Greenland. The records are extending from the Holocene to the Eem interglacial 130,000 years B.P. The contrast to the Southern Hemisphere records is striking, with a decreasing concentration of MSA with the advance of glaciation but an increasing concentration of non‐seasalt sulfate. A strong linear relationship is found in the Renland ice core between the ratio of MSA to non‐seasalt sulfate and the temperature, with higher ratios associated with warmer climatic stages, while the opposite relationship to temperature is found in the Vostok ice core. A more complicated picture is emerging of the use of MSA in ice cores as a quantitative tracer which suggests that previous interpretations can have been overly simplistic. Copyright 1993 by the American Geophysical Union."
"24606987600;","Atmospheric light absorption-A review",1993,"10.1016/0960-1686(93)90104-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027551656&doi=10.1016%2f0960-1686%2893%2990104-7&partnerID=40&md5=0a1bdcb95a63dd9f173a3eef1d7c5bdf","The atmosphere interacts both with incoming as well as outgoing light. Two main processes take place: light scattering and light absorption. Whereas light scattering redistributes any ligh energy in the atmosphere, light absorption converts the light energy to internal energy of the absorbing molecules and eventually transfers it to the surrounding gas as heat. Atmospheric gases absorb light in distinct spectral regions usually at more or less broad bands. Best known is the broad absorption of ozone in the far u.v., being essential for the existence of the biological macromolecules on Earth. Gases known as greenhouse gases, e.g. CO2, CH4, N2O and water vapor absorb a wide range of infrared radiation, and thus are responsible for the greenhouse effects. Since the lifetime of these gases (except water vapor) is considerable, their distribution around the globe is fairly homogeneous. The atmospheric aerosol gives the major contribution to the atmospheric light absorption in the visible and near u.v. and near i.r. Graphitic (black) carbon, the main constituent of soot, is almost exclusively responsible for the light absorption of the particles. The light absorption by aerosols is continuous and covers the whole visible spectral range. It only depends slightly on wavelength. The optical properties of elemental carbon are determined by the size of the particles and their complex refractive index. A variety of refractive indices can be found in the literature for elemental carbon, most likely caused by different production and thus composition of the particles. Soot particles are very efficient in attenuating light; for the average size the particles have more than twice the mass extinction coefficient compared to transparent particles such as ammonium sulfate. The light absorption coefficient of a mixture of elemental carbon and transparent materials is higher for internal than for external mixtures. When incorporated into transparent particles, the absorption properties of elemental carbon can be multiplied and the single scattering albedo will decrease in comparison to an external mixture of the same materials. There are different methods to measure the light absorption coefficient of suspended particles. They can be separated in three groups, depending on the effect or methodology they use, but no standard procedure has been adopted so far. Soot is produced by all combusttion processes. Since most fires on Earth are due to humans, then indirectly humans are the major source of light-absorbing aerosol particles. On a global scale black carbon amounts to 1.1-2.5% of the anthropogenic particles and to 0.2-1% of the total emitted particles. The emission factors for elemental carbon are highest for small sources such as diesel motors or fireplaces. The light-absorbing aerosol consists of fine particles, with most particles having diameters less than a few tenths of a micrometer. Particles in the size range of soot particles have an average lifetime of 7 days in the atmosphere, therefore they can be transported over large distances and are also found in remote regions. Since light-absorbing particles have a variety of sources and sinks and they are involved in precipitation cycles, their distribution on the globe is inhomogeneous. Light-absorption coefficients of the atmospheric aerosol reported in the literature differ by more than four orders of magnitudes at different locations, but nevertheless black carbon particles have been found even at very remote areas, such as the South Pole. Although light-absorbing particles are a minority component in the atmospheric aerosol, their effects cannot be neglected: since the mass extinction coefficient of soot is higher by a factor of two to three compared to transparent particles, light-absorbing substances in the atmosphere can cause at some locations up to half of the visibility reduction; light-absorbing substances in the atmosphere can be responsible for the brown appearance of urban hazes and the discoloration of the sky. The light absorption of the atmosphere in the visible (which mainly is due to particulate matter) has to be taken into account when considering radiative properties and climatic consequences. A small temperature increase due to absorption in the visible is to be expected. The value is around a few tenths of a Kelvin, but no general statement on its magnitude is possible, since a large spatial and temporal variation exists and other factors like surface albedo, the optical depth of the aerosol, its incorporation in clouds and humidity growth of the aerosol have to be considered. © 1993."
"6602682502;","The Tambora eruption in 1815 provides a test on possible global climatic and chemical perturbations in the past",1992,"10.1007/BF00127136","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026495661&doi=10.1007%2fBF00127136&partnerID=40&md5=18d04658264ee3537882f98a557636e1","A coupled one-dimensional radiative-convective-photochemical diffusion model, which takes into account the influence of ocean inertia on global radiative perturbations is used to investigate the possible climatic and other atmospheric effects of a major volcanic eruption, thought to be similar in magnitude to that of the Tambora eruption, Indonesia, which took place in 1815. A volcanic cloud was introduced in the model stratosphere between 20-25 km and the global average peak aerosol optical thickness was assumed to be 0.25. Both the aerosol optical thickness and aerosol composition, which determine the optical properties, were allowed to vary in the model atmosphere during the life cycle of the volcanic cloud. The results indicate that the global average surface temperature decreases steadily from the date of eruption (7-12 April 1815) with maximum cooling of 1° K occurring in the spring of 1816. The calculations also show significant warming of the stratosphere, with temperature increasing up to 15° K at 25 km in less than six months after the date of eruption. The important effects of the Tambora eruption on stratospheric ozone and UV-B radiation at the surface are also mentioned. © 1992 Kluwer Academic Publishers."
"7003984663;6603889543;","An automated recording atmometer: 2. evaporation measurement on a high elevation transect in Hawaii",1992,"10.1016/0168-1923(92)90009-S","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027072020&doi=10.1016%2f0168-1923%2892%2990009-S&partnerID=40&md5=3141740f6d5b1f29d1908e18b2a035ae","A transect of five recording atmometers was maintained over a 3-year period to monitor evaporative demand between 950 and 3000 m on the leeward slope of Haleakala Volcano, Maui, Hawaii. This elevation range traverses a portion of the slope where the persistent trade-wind inversion produces distinct vertical climate zonation, grading from a moist marine environment to extreme aridity above the inversion. Mean annual evaporation rates of 3.51 mm day -1 at both 950 and 1650 m, 3.64 mm day-1 at 2130 m, 4.82 mm day-1 at 2500 m, and 6.03 mm day-1 at 3000 m suggest a minimum between 950 and 1650 m where a cloud layer typically develops each morning. Monthly mean evaporation rates along the transect range from 2.3 mm day-1 at 950 m in December to 8.1 mm day-1 at 3000 m in August. Pronounced annual cycles are evident at the three highest stations. Midday evaporation is greatest at the upper two stations and least at 1650 and 2130 m. Differences in evaporation variability suggest that humidity changes associated with movements of the inversion are a major source of variation in the evaporation rate at high elevations. © 1992."
"57203346076;7003361967;","The greenhouse effect",1992,"10.1007/BF01904998","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027042407&doi=10.1007%2fBF01904998&partnerID=40&md5=556d2b9dee2c00565c2067c75f9327ff","The greenhouse effect on the Earth is identified by the difference between the effective radiating temperature of the planet and its surface temperature. The difference between the energy emitted by the surface and that emitted upward to space by the upper atmosphere quantifies it; it can therefore be defined as the long wave energy trapped in the atmosphere. Climate forcing and the response of the climate system within which climate feedback mechanisms are contained, will be defined in this review. Quantitative examples will illustrate what could happen if the greenhouse effect is perturbed by the human activities, in particular if atmospheric CO2 concentrations would double in the future. Recent measurements by satellites of the greenhouse effect will be given. The net cooling effect of clouds on the Earth and whether or not there will be less cooling by clouds as the planet warms, are discussed following a series of papers recently published by Ramanathan and his collaborators. © 1992 Kluwer Academic Publishers."
"6701791841;6603318887;","Global radiation climate changes in Israel",1992,"10.1007/BF00142962","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0006396294&doi=10.1007%2fBF00142962&partnerID=40&md5=f08ec431553055b17dec0733d96a74ea","A detailed study of the 26-year series of global radiation K↓, measurements at Bet Dagan, the Israel Meteorological Service's pyranometer station in the central coastal plain of Israel, confirmed earlier findings of a significant reduction in insolation which were based on a small sample of this data set (Stanhill and Moreshet, 1992). Between 1956 and 1987 the annual reduction averaged 45.2 ± 4.3 MJ m-2, equivalent to -0.63% yr-1. Relatively the reduction was greater in midwinter (-0.91% yr-1), than midsummer (-0.56% yr-1), and under average (-0.63% yr-1), than cloudless (-0.48% yr-1) sky conditions. No changes were found in the degree of cloud cover observed at Bet Dagan. The annual decrease of K↓ at Bet Dagan was highly correlated (r = -0.78) with the increase in the number of motor vehicles using the major roads passing within 1 km of the site: each additional vehicle passing was associated with a 21.5 J m-2 decrease in K↓ The causal nature of this correlation was confirmed by the difference of 18% found in daily values of K↓ measured at Bet Dagan under traffic-free and extremely congested road conditions. The reduction in the K↓ at Bet Dagan could not, however, be attributed exclusively to the increase in motor traffic in the immediate vicinity of the site, as no significant difference was found in values measured at a relatively traffic-free site 2 km downwind of the pyranometer station. The effect of aerosol pollutants originating in Tel Aviv - the major urban and industrial connurbation upwind of Bet Dagan - was confirmed by the changes recorded in the relative size of the direct and diffuse components of K↓ measured at this site. The importance of pollution from Tel Aviv would also explain the absence of any significant changes in the annual values of K↓ measured at Jerusalem, a smaller and less industrialized urban center 46 km downwind of Bet Dagan, or at Qidron, an uninhabited, isolated site on the NW coast of the Dead Sea, 25 km further downwind. © 1992 Kluwer Academic Publishers."
"7003696491;","Global warming: greenhouse gases versus aerosols",1992,"10.1016/0048-9697(92)90491-A","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026616276&doi=10.1016%2f0048-9697%2892%2990491-A&partnerID=40&md5=c6c4ba382f25c929ba8c1aa4f9581aaa","Man's activities have led to an increase in the atmospheric concentration of aerosols and the aerosol precursors as well as to an increase of greenhouse gases. A crude measure of man's global activities, which cause these increases, is the annual emission of carbon in the form of CO2 from the burning of fossil fuels. Hence as a first approximation, the additional releases of greenhouse gases and the additional production of aerosols are assumed to be proportional to the annual carbon emissions. A simple OD-model provides an estimate of the responses of the global annual average surface temperature to the increase of greenhouse gases and of aerosols. The albedo increase is estimated under the assumption that the additional aerosol production leads to a proportional increase in available cloud condensation nuclei and that the increase of greenhouse gases leads to a proportional decrease in the infrared transmittance of the atmosphere. Both effects are of the same magnitude but of opposite sign; hence, climate modelling requires the full inclusion of aerosols. © 1992."
"24781874900;57064071500;6506465964;","A further study on an extended nonlinear ocean-atmosphere coupled hydrodynamic characteristic system and the abrupt feature of ENSO events",1992,"10.1007/BF02656936","https://www.scopus.com/inward/record.uri?eid=2-s2.0-51649134754&doi=10.1007%2fBF02656936&partnerID=40&md5=4098c1c14c992aa3f541759c2344b8b8","In this paper, the decade data of meteorological satellite and surface meteorological observation of China have been analysed. The relationship between cloud and radiation has been studied. A set of empirical formulae of the ralationships between the albedo and cloud amount, the outgoing longwave radiation and cloud amount in Chinese different districts and different seasons has been deduced. They express simply the response of both planet reflectivity and earth-atmosphere outgoing longwave radiation to the change of cloud amount. So that the sensitivity of net radiation of the earth-atmosphere system to the change of cloud amount and the ratio of cloud reflective effect to greenhouse effect can be estimated. In this paper, the radiative process of the earth-atmosphere system, cloud and radiative balance and its effect on climate have been synthetically studied. © 1992 Advances in Atmospheric Sciences."
"6603765232;7401482713;","Pasture canopy temperature under cloudy humid conditions",1992,"10.1016/0168-1923(92)90079-J","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027039333&doi=10.1016%2f0168-1923%2892%2990079-J&partnerID=40&md5=cea8afcfb715ea8ac117ead80eae0b0f","The temperature of a forage canopy, which is determined primarily by climate conditions and plant water status, is an important regulator of the forage's physiological processes. Canopy temperature measurements are widely taken as an indicator of plant-water status under arid, sunny conditions. This study was conducted to determine the canopy temperature response of orchardgrass (Dactylis glomerata L.) to the high humidity and variable radiation levels of Appalachia. Average hourly climate parameters were measured along with average hourly canopy temperature and daily evapotranspiration from a monolith lysimeter at the North Appalachian Experimental Watersehd at Coshocton, Ohio, from Day 110 through 183 of 1989. The responses during a reference spring with plentiful rainfall indicate that canopy temperature decreased 2.1°C for a 1 kPa increase in vapor pressure deficit and increased 0.6°C for each 100 W m-2 increase in net radiation. The levels of average hourly wind during this period had no significant effect on canopy temperature. Aerodynamic and canopy resistances calculated from canopy temperature responses to vapor pressure deficit and net radiation were consistent except at net radiation levels below 100 W m-2. Reductions in canopy height by a half, as a result of lodging, had no pronounced effect on evapotranspiration or canopy temperature. The response of canopy temperature to changes in climate conditions was as reliably determined under cloudy humid conditions as under sunny conditions. © 1992."
"57210518852;7003666669;","An analysis of cloud liquid water feedback and global climate sensitivity in a general circulation model",1992,"10.1175/1520-0442(1992)005<0907:AAOCLW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0006832095&doi=10.1175%2f1520-0442%281992%29005%3c0907%3aAAOCLW%3e2.0.CO%3b2&partnerID=40&md5=9f0f7fe1301b592b74f5a6fa10fbb341","A set of general circulation model simulations is analyzed to determine how cloud distribution and cloud radiative properties might change as climate warms and to isolate and quantify the various feedback effects of clouds on climate sensitivity. For this study the NCAR Community Climate Model (CCM1) was modified so that the cloud radiative properties (albedo, emissivity, and absorptivity) are no longer prescribed, but are functions of the cloud liquid water content. Following the Cess and Potter approach for estimating climate sensitivity, we consider results from two sets of simulations. In one set, cloud liquid water is diagnosed from the simulated condensation rate and thus is free to vary with condensation, while in the other set, the cloud liquid water content is a fixed field (dependent only on altitude and latitude) that is obtained by averaging the results of the first set of experiments. The experiments make it possible to isolate the effects of cloud liquid water feedback. We find that changes in cloud amount, cloud liquid water content, and cloud distribution (especially in the vertical) are all of comparable importance, but some of these changes provide a positive feedback while others provide a negative feedback. Separation of cloud feedback into individual components makes it clear that in this model as climate warms the general increase in the liquid water content of each cloud layer is partially offset by an upward shift in cloud altitude. The effects of clouds on longwave radiation also generally tend to cancel the effects on shortwave radiation. Consequently, the net cloud feedback represents a residual of several offsetting effects, which nevertheless is large enough to nearly double the sensitivity of the simulated climate. Another important conclusion is that it is impossible to parameterize cloud albedo in terms of average cloud liquid water content because the average liquid water is dominated by the thicker clouds, whereas the average albedo depends on clouds with relatively little liquid water as well. © 1992 American Meteorological Society."
"7005070958;7201635744;7006783796;7004286811;13406672500;7202206836;","Interpretation of seasonal cloud-climate interactions using Earth Radiation Budget Experiment data",1992,"10.1029/92JD00547","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026463562&doi=10.1029%2f92JD00547&partnerID=40&md5=f83efa2c5e24075cee64e5b0e0a01271","By employing Earth Radiation Budget Experiment data it is demonstrated that, relative to the annual-mean climate, seasonal cloud variations produce radiative heating of the surface-atmosphere system in the summer hemisphere, together with cooling in the winter hemisphere. It is further illustrated that this is an integrated effect resulting from the combination of seasonal variations in cloud amount, cloud vertical distribution, and cloud optical depth. -from Authors"
"6603288408;","Marine stratocumulus cloud clearing episodes observed during FIRE",1992,"10.1175/1520-0493(1992)120<0565:MSCCEO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026613195&doi=10.1175%2f1520-0493%281992%29120%3c0565%3aMSCCEO%3e2.0.CO%3b2&partnerID=40&md5=f9c34978e6221edd2ba6d14214e2dd76","These synoptic-to-mesoscale clearing episodes appear to be correlated with the ridging of the Pacific subtropical anticyclone into the United States Pacific Northwest, resulting in offshore flow effects. Furthermore, the subsidence associated with the Pacific subtropical anticyclone may help cause the clearing episodes, or prevent the redevelopment of these clouds in the clear regions. Because of the contribution of marine stratocumulus clouds to the global albedo, the clearing of large regions of these clouds may impact climate. -from Author"
"7006377579;7006235542;","A parameterisation of the effective radius of ice free clouds for use in global climate models",1992,"10.1016/0169-8095(92)90038-C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026447348&doi=10.1016%2f0169-8095%2892%2990038-C&partnerID=40&md5=2756ada759deb53f908686b1da179e75","The variation of the droplet effective radius with height above cloud base and liquid water content has been examined for several different cloud types forming in widely separated parts of the world. The clouds examined are marine stratocumulus over the Pacific Ocean, cumulus clouds forming over continental USA, cap clouds enveloping Great Dun Fell in the UK, and stratocumulus and small cumulus clouds forming over the UK. The clouds differ markedly in their behaviour due principally to the large variation in the concentration of cloud condensation nuclei between the oceans and the continents and the differing roles of dry air entrainment in the different cloud types. The latter effect is seen to be a maximum in cumulus clouds which are strongly affected by the mixing process. Radiative cooling from the stratocumulus is also significant in these cloud types. The results obtained have been used to suggest improvements to the input data used in the parameterisation of the radiative properties of clouds in Global Climate Models. © 1992."
"7007175473;7202162685;","A parameterization of ice cloud optical properties for climate models",1992,"10.1029/91JD02472","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026470472&doi=10.1029%2f91JD02472&partnerID=40&md5=219c5f6ff2c4ddcb6152658ce289c11c","Five spectral intervals in the shortwave and five intervals in the infrared are employed, with the ice cloud optical properties parameterized in terms of ice water path (IWP) and the effective radius (re) of the ice crystal size distribution. The parameterization thus allows the flexibility of varying the ice water path and effective radius independently of each other. The parameterized optical properties are used to calculate the bulk reflectivity, transmissivity, and emissivity for cirrus clouds with realistic ranges of IWP and re. For a given change in cloud optical depth a change in re alone is more effective than a change in IWP alone in altering the shortwave reflectivity and therefore in altering the strength of the cloud albedo feedback. -from Authors"
"7003543851;","Validation of cloud forcing simulated by the National Center for Atmospheric Research Community Climate Model using observations from the Earth Radiation Budget Experiment",1992,"10.1029/92jd01495","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027087982&doi=10.1029%2f92jd01495&partnerID=40&md5=2c986d9036effe85ba0b37657b0474ba","The comparison reveals several deficiencies in the CCM cloud representation. Most notable are the difficulties in properly simulating the effect of clouds on the planetary albedo. This problem arises from discrepancies in the model's portrayal of low-level cloudiness and leads to significant errors in the absorbed solar radiation simulated by the model. The CCM performs much better in simulating the effect of clouds on the longwave radiation emitted to space, indicating its relative success in capturing the vertical distribution of cloudiness. The daily variability of the radiative effects of clouds in both the shortwave and longwave spectral regions is systematically overestimated. -from Author"
"7005496842;6701574871;","A comprehensive radiation scheme for numerical weather prediction models with potential applications in climate simulations",1992,"10.1175/1520-0493(1992)120<0303:ACRSFN>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026486877&doi=10.1175%2f1520-0493%281992%29120%3c0303%3aACRSFN%3e2.0.CO%3b2&partnerID=40&md5=1b23e4e8a822bd0bc16dc066da5d6211","The scheme is based on the solution of the δ-two-stream version of the radiative transfer equation incorporating the effects of scattering, absorption, and emission by cloud droplets, aerosols, and gases in each part of the spectrum. An extremely flexible treatment of clouds is obtained by allowing partial cloud cover in any model layer and relating the cloud optical properties of the cloud liquid water content. The latter quantity may either be a prognostic or diagnostic variable of the host model or specified a priori depending on cloud type, height, or similar criteria. The treatment of overlapping cloud layers is based on realistic assumptions. The scheme has been tested extensively in the framework of the intercomparison of radiation codes in climate models. Radiative fluxes and heating rates, calculated in a few milliseconds of CPU time with our scheme, are in very good agreement with reference calculations, which may require several thousand CPU seconds for the same purpose. -from Authors"
"7409715636;7408612236;","The significance of cloud-radiative forcing to the general circulation on climate time scales - a satellite interpretation",1992,"10.1175/1520-0469(1992)049<0845:tsocft>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027100756&doi=10.1175%2f1520-0469%281992%29049%3c0845%3atsocft%3e2.0.co%3b2&partnerID=40&md5=38e851f49be5253cbae6de50afce68bc","Cloud-radiative forcing calculations based on Nimbus-7 radiation budget and cloudiness measurements reveal that cloud-induced longwave (LW) warming (cloud greenhouse influence) is dominant over the tropics, whereas cloud-induced shortwave (SW) cooling (cloud albedo influence) is dominant over mid- and high-latitudes. The average SW cloud cooling taken over the area of the globe from 65°N to 65°S is -27.8 W m-2. This magnitude slightly overcomes LW cloud warming (-25.7 SW m-2), resulting in a small net cooling effect of -2.1 W m-2 over 93% of the earth. A 6-yr zonally averaged mean cloudy- and clear-sky net radiation flux analysis shows that there are three distinct regimes in terms of net cloud warming or cooling, that is, warming in the tropics (between 230°N and 20°S) and in the high latitudes (poleward of 55°) and cooling in the extratropical latitudes between 20° and 55° in both hemispheres. -from Authors"
"7202155374;7202257430;","Impacts on regional climate of Amazon deforestation",1992,"10.1029/92GL01905","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027036738&doi=10.1029%2f92GL01905&partnerID=40&md5=df65c8f6254492561ee44f082bb409a0","A simulation of the climate response to Amazon deforestation has been carried out. Precipitation is decreased on the average by 25% or 1.4 mm/day, with ET and runoff both decreasing by 0.7 mm/day. Modifications of surface energy balance through change of albedo and roughness are complicated by cloud feedbacks. The initial decrease of the absorption of solar radiation by higher surface albedos is largely cancelled by a reduction in cloud cover, but consequent reduction in downward longwave has a substantial impact on surface energy balance. Smoke aerosols might have an effect comparable to deforestation during burning season. Copyright 1992 by the American Geophysical Union."
"7007088807;","Over and under estimation of cloud amount: Theory and romanian observations",1992,"10.1080/01425919208909740","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0009512314&doi=10.1080%2f01425919208909740&partnerID=40&md5=62176fcf09eac2ec85f4f4fe5d1fed6c","Cloud cover estimates made by trained weather observers are subjective and prone to projection and perspective errors. The paper proposes a theoretical procedure to determine the real value of the average cloud amount for a given time interval (Nreal). In case of the climate and latitudes of Romania the observed value of cloud amount (Nobs) exceeds ther real one. The results we obtained are compared with those reported by other authors. © 1992, Taylor &amp; Francis Group, LLC. All rights reserved."
"6603451961;","Delta-Eddington approximation for solar radiation in the NCAR community climate model",1992,"10.1029/92JD00291","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026439814&doi=10.1029%2f92JD00291&partnerID=40&md5=3068105f605de652a55e1c3e6c21f22b","Absorption parameterizations for H2O, O3, CO2, and O2 were developed by making use of the latest theoretical calculations. Water droplet scattering and absorption are parameterized as shown by Slingo (1989). An accurate and efficient convolution of the H2O vapor spectrum with water droplet clouds is presented that yields good agreement with available line-by-line (LBL) calculations for single-layer clouds. A simple and efficient method to simulate partial cloud cover and cloud overlap is included. The simulated albedo-solar zenith angle dependence agrees very well with adding/doubling scattering calculations. The CCM2 δ-Eddington method will make possible many interesting applications of CCM2 in the years to come. -from Author"
"6603942055;7004411888;","Contribution to the cloud droplet effective radius parameterization",1992,"10.1029/92GL02283","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027087871&doi=10.1029%2f92GL02283&partnerID=40&md5=3a29cce7e38d4cbd8ea1e634b0442d4f","An analytic cloud droplet effective radius expression is derived and validated by using field experiment microphysical data. This expression shows that the effective radius depends simultaneously upon the cloud liquid water content, droplet concentration and droplet spectral dispersion. It further suggests that the variability in these parameters present at all scales, due to turbulent mixing and secondary droplet activation, could limit the accuracy of the effective radius parameterizations used in climate models. Copyright 1992 by the American Geophysical Union."
"57153521700;7409853077;","Effects of cloud optical property feedbacks on the greenhouse warming",1992,"10.1175/1520-0442(1992)005<0814:EOCOPF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027091279&doi=10.1175%2f1520-0442%281992%29005%3c0814%3aEOCOPF%3e2.0.CO%3b2&partnerID=40&md5=fe999ec1f2fa162476bf313d74318e09","Cloud optical properties, in particular the optical thickness τ, affect the earth-atmosphere radiation budget, and their potential changes associated with climate changes may induce feedback effect. A one-dimensional radiative-convective model was used to illustrate that the difference in the vertical distribution of the radiative forcing between CO2 increase and changes of solar constant can result in a different τ feedback. Recently, Wang et al. carried out a general circulation model study of the climatic effect of atmospheric trace gases CH4, CFCs, and N2O, and the model results indicate that these trace gases provide an important radiative energy source for the present climate. Because the radiative-forcing behavior of CO2 is different from that of these other gases, the simulations also show that different radiative forcing can lead to quite different climatic effects. -from Authors"
"6507077014;7006689582;7102541803;","Estimation of the influence of characteristics of the hydrologic cycle on global climate sensitivity to anthropogenic effects",1992,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027028952&partnerID=40&md5=aa80d9ed07031b520752d9e7cfa0b3f8","The influence of the characteristics of the hydrologic cycle of the atmosphere and land on the sensitivity of a thermodynamic climate model to anthropogenic effects, including the variations in the carbon dioxide content qCO2 and the optical aerosol thickness τa in the atmosphere is estimated. Incorporation of the variable soil moisture content in the model leads to an increase in the sensitivity of the model to qCO2 and τa variations. An appreciable difference between the latitudinal boundaries of the zones with negative and positive variations in precipitation intensity and soil moisture content is noted. The dependence of the characteristics of the climate model sensitivity to a doubling of qCO2 on the correlation of clouds of different layers is estimated. -Journal summary"
"24511929800;56283400100;","Cloud-radiation feedbacks in a general circulation model and their dependence on cloud modelling assumptions",1992,"10.1007/BF00211155","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027066656&doi=10.1007%2fBF00211155&partnerID=40&md5=e25467c78ed91dc649c15618dbcfe280","The general circulation model (GCM) used in this study includes a prognostic cloud scheme and a rather detailed radiation scheme. In a preceding paper, we showed that this model was more sensitive to a global perturbation of the sea surface temperatures than most other models with similar physical parametrization. The experiments presented here show how this feature might depend on some of the cloud modelling assumptions. We have changed the temperature at which the water clouds are allowed to become ice clouds and analyzed separately the feedbacks associated with the variations of cloud cover and cloud radiative properties. We show that the feedback effect associated with cloud radiative properties is positive in one case and negative in the other. This can be explained by the elementary cloud radiative forcing and has implications concerning the use of the GCMs for climate sensitivity studies. © 1992 Springer-Verlag."
"7409571791;7409716893;","Climate of China",1992,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040954769&partnerID=40&md5=fdf7c694172219c6a3725a6cc9f03e80","This book examines all aspects of climatology in China. A brief introduction discusses the definition of climate and discusses the development of Chinese climatology. The remaining twelve chapters move logically through the different elements of the climate: general circulation and weather systems; air temperature; precipitation; humidity and evaporation; cloud amount; sunshine duration and total solar radiation; wind velocity; earth temperature and frozen soil; weather phenomena; delineation of Chinese climatic regions; climatic variation over China; causes of formation and variation of climate, and climatic resources and adversities of China. Appendices giving 30-year climatic normals over selected Chinese stations and an index are included. -R.Gower"
"7003430284;7007108728;7003535385;6701757453;7006705580;","The relationship between cloud droplet number concentrations and anthropogenic pollution: observations and climatic implications",1992,"10.1029/91JD02739","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026465248&doi=10.1029%2f91JD02739&partnerID=40&md5=8166fff101f0bfa500d400a1a7adcba7","Measurements of the concentrations of sulfate and nitrate in approximately 400 cloud water samples collected during four field studies carried out since 1982 are used with coincident measurements of cloud droplet number concentrations (CDNC) and liquid water content (LWC) to examine the relationship between CDNC and anthropogenic pollution, where sulfate concentration is used as the measure of the latter. The number of samples is compressed to 92 by averaging duplicates and multiple samples at similar altitudes during any particular flight, with 85 including CDNC measurements. Positive linear regressions between log (CDNC) and log (cloud water sulfate concentration) are determined for both stratiform and cumuliform cloud. Because of the number of factors affecting the CDNC, the coefficients of determination are only 0.30 and 0.49 for the respective cloud types. The present-day climatic forcing due to cloud albedo change arising from increased CDNC is estimated from a rudimentary model at between -2 W m-2 and -3 W m-2 for eastern North America. -from Authors"
"6603164038;7402546593;7201914101;7004325649;6506702741;","Cumulus Cloud Base Height Estimation from High Spatial Resolution Landsat Data: A Hough Transform Approach",1992,"10.1109/36.142921","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026868264&doi=10.1109%2f36.142921&partnerID=40&md5=b146fa84d49c09179c09d22089a13fbc","Cloud base height is an essential variable governing surface energy budgets, but it is notoriously difficult to determine using satellite data. This study develops a semiautomated methodology to estimate cumulus cloud base heights using high spatial resolution LANDSAT Multispectral Scanner data. The approach employs a variety of image processing techniques to match cloud edges with their corresponding shadow edges. Cloud base height then is estimated by computing the separation distance between the corresponding Generalized Hough Transform reference points. Sixteen subregions, each 30 km x 30 km in size, are selected for four LANDSAT scenes. Standard deviations of cloud base height within each of the subregions range from about 100m to 150m. Differences between cloud base heights computed using the Hough Transform and a manual verification technique are small (on the order of 100m or less). The cloud base heights also compare favorably with the few surface observations available. On the basis of these results, it is estimated that cloud base height accuracies of 50–70m may be possible using HIRIS and ASTER instruments in the EOS Global Climate Change program. © 1992 IEEE"
"7007067997;7003932249;7004159070;","Infrared emittance of water clouds",1992,"10.1175/1520-0469(1992)049<1459:IEOWC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027066438&doi=10.1175%2f1520-0469%281992%29049%3c1459%3aIEOWC%3e2.0.CO%3b2&partnerID=40&md5=fe86c92c4c21076040cd55dcfbee69ad","A simple approximation has been developed for the infrared emittance of clouds composed of water spheres based on the absorption approximation for the emittance and on the polynomial aproximation to the Mie absorption efficiency. The expression for the IR emittance is obtained in a simple analytical form as a function of the liquid water content and two size distribution parameters, namely, the effective radius and effective variance. The approximation is suitable for numerical weather prediction, climate modeling, and radiative transfer calculations. The accuracy, when compared to the exact Mie calculation and integration over the size distribution, is within a few percent, while the required computer time is reduced by several orders of magnitude. In the limit of small droplet sizes, the derived IR emittance reduces to a term proportional to the liquid water content. -Authors"
"57190931873;","IAMAP 1991: The joys of international science",1992,"10.1029/91EO00204","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984446154&doi=10.1029%2f91EO00204&partnerID=40&md5=21a36e0a8323a7429bcc328d8e9a73eb","Need to know the latest about lightning location and its application to the forecasting of meteorological phenomena and the global circuit? Electrical properties of thunderstorms? Aerosol‐cloud‐climate interactions? The parameterization of complex terrain effects in regional and large scale models? ©1992. American Geophysical Union. All Rights Reserved."
"25941200000;","Solar Radiative Transfer Through Clouds Possessing Isotropic Variable Extinction Coefficient",1992,"10.1002/qj.49711850807","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027078910&doi=10.1002%2fqj.49711850807&partnerID=40&md5=bf3861c56588ddcd14097bff0dc940bb","Solar radiative fluxes were computed for heterogeneous clouds using an extension of the Monte Carlo method of photon transport which assumes that clouds possess isotropic variability. Hence, computation of fluxes for three‐dimensional (3‐D) clouds can be achieved with only an extended, characteristic one‐dimensional (1‐D) transect of extinction coefficient, β. These are easily obtained by aircraft measurements. In order to validate the new scheme, fluxes for 3‐D, stochastic multiplicative cascade clouds were computed by the conventional approach to Monte Carlo simulation. 1‐D transects through these clouds were then strung together and used in the new scheme. Not only do both methods of calculation yield statistically identical flux estimates, but they also produce virtually identical distributions of photon optical pathlengths and number of scattering events. Furthermore, the new technique may require an order of magnitude less computation time, depending on the desired level of accuracy. Cloud microphysical data obtained by aircraft were used to represent characteristic transects of β, and corresponding fluxes were computed with the new scheme. Results suggest that internal inhomogeneity reduces cloud albedo below homogeneous values by about 5‐10% for overcast and isolated cubic clouds. Also, it is predicted that for overcast clouds of optical depth τ < (>) ≈ 40, inhomogeneous clouds absorb less (more) radiation relative to their homogeneous counterparts. Three individual and trivial modifications of a plane‐parallel, homogeneous two‐stream solution of the radiative‐transfer equation appear to be capable of capturing the essential effects of inhomogeneity. This is promising for incorporation of inhomogeneous cloud effects into existing climate‐model solar‐radiation routines. Little evidence, however, was found to suggest that the effects of inhomogeneity alone can explain the spectral aspects of the cloud absorption/albedo anomaly problem. Copyright © 1992 Royal Meteorological Society"
"7006212144;7003298991;7003627297;7102236054;6503959524;43561538600;7004213761;","Chemical climatology of high elevation spruce-fir forests in the southern Appalachian mountains",1992,"10.1016/0269-7491(92)90061-E","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026613849&doi=10.1016%2f0269-7491%2892%2990061-E&partnerID=40&md5=9c273571663ca67c2305ac38a46efcd7","The physical and chemical climatology of high elevation (&gt; 1500 m) spruce-fir forests in the southern Appalachian mountains was studied by establishing a weather and atmospheric chemical observatory at Mt Mitchell State Park in North Carolina (35° 44′ 05″ N, 82° 17′ 15″W). Data collected during the summer and autumn (May-October) of 1986, 1987, and 1988 are reported. All measurements were made on or near a 16·5 m walk-up tower extending 10 m above the forest canopy on Mt Gibbes (2006 m msl), which is located approximately 2 km SW of Mt Mitchell. The tower was equipped with standard meteorological instrumentation, a passive cloud water collector, and gas pollutant sensors for O3, SO2, NOx. The tower and nearby forest canopy were immersed in clouds 25 to 40% of the time. Non-precipitating clouds were very acidic (pH 2·5-4·5). Precipitating clouds were less acidic (pH 3·5-5·5). The dominant wind directions were WNW and ESE. Clouds from the most common wind direction (WNW) were more acidic (mean pH 3·5) than those from the next most common wind direction (ESE, mean pH 5·5). Cloud water acidity was related to the concentration of SO42-, and NO3- ions. Mean concentration of H+, NH4+, SO42-, and NO3- ions in the cloud water varied from 330-340, 150-200, 190-200 and 120-140 μmol litre-1 respectively. The average and range of O3 were 50 (25-100) ppbv (109) in 1986, 51 (26-102) ppbv in 1987, and 66 (30-140) during the 1988 field seasons, respectively. The daily maximum, 1-h average, and 24-h average concentrations were all greatest during June through mid-August, suggesting a correlation with the seasonal temperature and solar intensity. Throughfall collectors near the tower were used to obtain a useful estimate of deposition to the forest canopy. Between 50-60% of the total deposition of SO42- was due to cloud impact. © 1991."
"7003440089;6602472532;7003941060;6602515302;7003361967;57203346076;","Simulation of the Last Glacial cycle by a coupled, sectorially averaged climate-ice sheet model. 2. Response to insolation and CO2 variations",1992,"10.1029/92jd01256","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001599260&doi=10.1029%2f92jd01256&partnerID=40&md5=d759f9affb4e21acaa86a5df9ee47beb","A two-dimensional climate model which links the Northern Hemisphere atmosphere, ocean mixed layer, sea ice, and continents has been asynchronously coupled to a model of the three main northern ice sheets and their underlying bedrock. The coupled model has been used to test the influence of several factors, including snow surface albedo over the ice sheets, in producing plausible ice age simulations using astronomically derived insolation and CO2 data from the Vostock ice core. The impact of potentially important processes, such as the water vapor transport, clouds, and deep sea circulation, was not investigated in this study. Sensitivity experiments show that ablation is more important to the ice sheet response than snow precipitation variations. A final set of experiments addresses the effects of CO2 on the simulated climate of the last glacial maximum and on a new long term experiment covering the last 122 kyr. -from Authors"
"43561538600;7006212144;","Regional analysis of cloud chemistry at high elevations in the eastern United States",1992,"10.1016/0960-1686(92)90085-Y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026908649&doi=10.1016%2f0960-1686%2892%2990085-Y&partnerID=40&md5=eb77535f6693e93b42126a625862d03c","Results from the collection and chemical analysis of cloudwater samples collected from May to October 1986-1988 from the five high-elevation ({greater-than or approximate}950 m MSL) Mountain Cloud Chemistry Program (MCCP) sites (Whiteface Mountain, NY; Mt Moosilauke, NH; Shenandoah Park, VA; Whitetop Mountain, VA; Mt Mitchell, NC) in the eastern United States are summarized. The resulting database documents the regional chemical climatology of high-elevation forest ecosystems in the eastern U.S. Clouds occured at these sites on 32-77% of the days during the sample collection period. More than 90% of cloud samples were acidic (prmpH&lt;5.0). The lowest cloudwater pH (2.29 integrated 1-h collection period) was recorded at Mt Mitchell, NC. At all sites sulfate and nitrate were the dominant anions and hydrogen and ammonium were the dominant cations in cloudwater samples. Mount Mitchell received the most acidic clouds and highest chemical exposures, while the Whiteface summit site received the least acidic and lowest chemical exposures compared to other MCCP high-elevation sites. Cloud pH and major chemical components exhibited a seasonal trend with the maxima during the summer months, and correlated well with temperature and ozone concentrations. The mean equivalent ratios of SO42- to NO3- were found to be 1.9-3.9 at these sites. It is noted that SO42- correlated highly with hydrogen ion, suggesting that contribution to cloud acidity by sulfate and/or its precursors may be significant. © 1992."
"57213539181;","Empirical Evidence for the Effect of Tropical Deforestation on Climatic Change",1992,"10.1017/S037689290003023X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026613524&doi=10.1017%2fS037689290003023X&partnerID=40&md5=a038ae7dfeece36142c8ff29d3385336","If large areas of tropical rain-forest are replaced by grassland, there is likely to be about 300 mm less evapo-transpiration and 650800 mm less rainfall during each year in these areas than is currently experienced. Lower rates of evapotranspiration will allow more energy to be used for sensible heat, and this will lead to surface air temperatures that are higher than currently by about 3°C. Reduced cloud-cover will also lead to even higher temperatures, because clouds have a net cooling effect. When this additional heat is combined with the extrasensible heating, the overall effect is expected to be a rise in temperature of about 4–5°C. These contentions are based upon data obtained from ‘natural experiments’. They have given results which suggest that tropical deforestation will have a larger effect on temperature than was hitherto expected, and that the effect on both temperature and rainfall will be more widespread than has been expected hitherto. The effects on global climate cannot as yet be determined by a ‘natural experiment’. The removal of so much of the tropical rain-forest as is now projected will have such a dramatic effect on local and even wider climate that no further replacement of the rain-forest ecocomplex by others or other land-uses should be allowed to take place. © 1992, Foundation for Environmental Conservation. All rights reserved."
"7401457331;","T. C. Chamberlin and H2O climate feedbacks: A voice from the past",1992,"10.1029/91EO00367","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984490292&doi=10.1029%2f91EO00367&partnerID=40&md5=e77aaa87039eebdc08bb6eb819528976","The interaction of positive and negative climate feedbacks has become a central issue for the global change science community. With many expecting surface air temperatures to rise several degrees due to increases in anthropogenic greenhouse gases, the response of H2O (water vapor, liquid, solid) is critical. Will higher temperatures and increased evaporation lead to an enhanced greenhouse effect, especially over the tropical oceans, or will increased cloudiness effectively cap the increase in temperatures? [see Ramanathan and Collins, 1991, 1992; Stephens and Slingo, 1992]. “Greenhouse Warming and Cloud Thermostats” is the name of a talk to be given by V. Ramanathan during the Atmospheric Sciences Section luncheon at the AGU 1992 Fall Meeting on December 8. This topic invites comparison between the current H2O feedback hypotheses and work begun almost a century ago by the celebrated geologist Thomas Chrowder Chamberlin (1843–1928) at the University of Chicago [Gillispie, 1970–1980; Schultz, 1976]. Briefly, here are some of Chamberlin's ideas on the roles of water vapor and clouds. ©1992. American Geophysical Union. All Rights Reserved."
"7102886537;7006550762;6604021707;","Pangaean climate during the early Jurassic: GCM simulations and the sedimentary record of paleoclimate",1992,"10.1130/0016-7606(1992)104<0543:PCDTEJ>2.3.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879890456&doi=10.1130%2f0016-7606%281992%29104%3c0543%3aPCDTEJ%3e2.3.CO%3b2&partnerID=40&md5=330c6feca670ae4ce3fc2957ec400bd5","Shows that increased ocean heat transport may have been the primary force generating warmer climates during the past 180 m.y. Three major features of the simulated Early Jurassic climate include the following. 1) A global warming, compared to the present, of 5°C to 10°C, with temperature increases at high latitudes five times this global average. Average summer temperature increases at high latitudes five times this global average. Average summer temperatures exceed 35°C in low-latitude regions of western Pangaea where eolian sandstones testify to the presence of vast deserts. 2) Simulated precipitation and evaporation patterns agree closely with the moisture distribution interpreted from evaporites, and coal deposits. High rainfall rates are associated primarily with monsoons that originate over the warm Tethys Ocean. These systems are found to be associated with localized pressure cells whose positions are controlled by topography and coastal geography. 3) Decreases in planetary albedo, occurring because of reductions in sea ice, snow cover, and low clouds, and increases in atmospheric water vapor are the positive climate feedbacks that amplify the global warming. Large seasonal temperature fluctuations occurred over mid- and high-latitude continental interiors. -from Authors"
"7003960899;","Comparisons of Multi‐Year Statistics of Selected Variables From the Coads and the Nimbus‐7 and Ecmwf Data Sets",1992,"10.1002/qj.49711850707","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027046285&doi=10.1002%2fqj.49711850707&partnerID=40&md5=a32308cd7fd01eac69bd994bc5cf125e","Coarse spatial resolution monthly statistics of selected variables of the Consolidated Ocean‐Atmosphere Data Set (COADS) have been compared with Nimbus‐7 satellite analyses and the European Centre for Medium‐range Weather Forecasts (ECMWF) operational analyses. Comparisons are made for the important cloud/climate variables of total cloudiness, surface air temperature and surface relative humidity. to ease these comparisons the COADS variances have been adjusted to account for small numbers of observations, and the COADS temperature and humidity data have been transformed to the 1000 mb level of the ECMWF analyses. The results show that the Nimbus‐7 cloud fractions tend to underestimate total cloudiness for much of the earth, especially in regions of substantial low cloud cover. After account has been made for the different observation heights, the COADS and the ECMWF annual mean temperature statistics are found to be in generally good agreement. However, the annual mean ECMWF relative humidities are significantly lower over large portions of the oceans. The interrelations between the Nimbus‐7 and the COADS total cloudiness and the ECMWF and the COADS lower‐level temperature and relative humidity are compared. Significant regional correlation patterns are evident in all cloud‐surface data pairs. On the other hand, some patterns of correlation using the Nimbus‐7 and the COADS cloud data are quite different, with those of the COADS generally appearing to be the more realistic. Copyright © 1992 Royal Meteorological Society"
"7005513582;6603451961;","Comparison of the observed and calculated clear sky greenhouse effect: implications for climate studies",1992,"10.1029/92jd00729","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027046387&doi=10.1029%2f92jd00729&partnerID=40&md5=8a5f0ac975e550d4bfa588d811d0a222","The clear sky greenhouse effect is defined in terms of the outgoing longwave clear sky flux at the top of the atmosphere. The present study investigates to what degree of accuracy this flux can be analyzed by using independent atmospheric and surface data in conjunction with a detailed longwave radiation model. The conclusion from this comparison is that for most regions over oceans the analyzed fluxes agree to within the accuracy of the ERBE-retrieved fluxes (±5 W m-2). However, in regions where deep convective activity occurs, the ERBE fluxes are significantly higher (10-15 W m-2) than the calculated fluxes. This bias can arise from either cloud contamination problems or variability in water vapor amount. -from Authors"
"57206927264;","The urban climate of Shanghai",1992,"10.1016/0957-1272(92)90033-O","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026614788&doi=10.1016%2f0957-1272%2892%2990033-O&partnerID=40&md5=32036f9be728b46c70017339bc789aa5","Shanghai is the most important industrial and commercial city in China in terms of population and building density, consumption of energy and development rate. Meteorological data from the urban Shanghai Central Observatory over the last 100 years are combined with similar 20-year data sets from 10 nearby suburban and rural stations to analyse climatic impacts from Shanghai's urbanization. Results show its urban heat island effect is large and has enhanced with time. The effect is more obvious in urban-rural differences of annual mean minimum temperatures than in annual mean temperatures. During recent decades, the urban centre of Shanghai has experienced lower wind speeds, lower humidity, fewer fog days, fewer sunny days, increased low cloudiness and increased overcast days. Concurrent variations at nearby rural stations were dissimilar. Solar radiation in urban Shanghai shows accelerating decreases of both direct solar radiation (S) and global radiation, but increase of both diffuse radiation (D) and average turbidity (D/S). © 1992."
"7003703412;6701853878;57213254653;","Global relationships among the Earth's radiation budget, cloudiness, volcanic aerosols, and surface temperature",1992,"10.1175/1520-0442(1992)005<1120:GRATER>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027047970&doi=10.1175%2f1520-0442%281992%29005%3c1120%3aGRATER%3e2.0.CO%3b2&partnerID=40&md5=301588cf49b1136f04c38f960bcf07df","Solar luminosity is apparently related to the global surface temperature in the 1979-1990 time period based on the Nimbus-7 observations and an extended Hansen and Lebedeff temperature dataset. The 0.40°C range in observed global temperatures may be partitioned into a 0.15°C component due to a 2 W m-2 change in the solar constant and a 0.22°C component due to the increasing concentration of CO2 and other greenhouse gases. The Nimbus-7 observations indicate that the global, annual cloud amount varies by +0.3% to -0.5% with a pronounced quasi-biennial periodicity and is inversely proportional to the outgoing longwave flux and surface temperature. The time dependence of aerosols injected into the stratosphere by the explosive 1982 eruption of El Chichon is found to be important, along with the global cloud amount, in describing the time dependence of the earth's albedo during the period. -from Authors"
"7409509094;","A solar radiation model for use in climate studies",1992,"10.1175/1520-0469(1992)049<0762:asrmfu>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027066440&doi=10.1175%2f1520-0469%281992%29049%3c0762%3aasrmfu%3e2.0.co%3b2&partnerID=40&md5=92b1b54da64738038e2c73370d89f2ef","It includes the absorption and scattering due to ozone, water vapor, oxygen, carbon dioxide, clouds, and aerosols. Rayleigh scattering is also included. The UV and visible region (λ<0.69 μm) is grouped into four bands. An effective coefficeint for ozone absorption and an effective cross section for Rayleigh scattering are computed for each band. In the near-infrared region (λ>0.69 μm), the broadband parameterization is used to compute the absorption by water vapor in a clear atmosphere, and the k-distribution method is applied to compute fluxes in a scattering atmosphere. The reflectivity and transmissivity of a scattering layer are computed analytically using the delta-four-stream discrete-ordinate approximation. The two-stream adding method is then applied to compute fluxes for a composite of clear and scattering layers. Compared to the results of high spectral resolution and detailed multiple-scattering calculations, fluxes and heating rate are accurately computed to within a few percent. -from Author"
"7403076976;7006550762;","A simple lightning parameterization for calculating global lightning distributions",1992,"10.1029/92JD00719","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027101680&doi=10.1029%2f92JD00719&partnerID=40&md5=ae6d276da47892cd43fbfba130416de3","Convective cloud top height is used as the variable in the parameterization, with different formulations for continental and marine thunderstorms. The parameterization has been validated using two lightning data sets: one global and one regional. In both cases the simulated lightning distributions and frequencies are in very good agreement with the observed lightning data. This parameterization could be used for global studies of lightning climatology; the Earth's electric circuit; in general circulation models for modeling global lightning activity, atmospheric NOx concentrations, and perhaps forest fire distributions for both the present and future climate; and, possibly, even as a short-term forecasting aid. -from Authors"
"7403346393;7406514318;7005374939;","Simulated diurnal range and variability of surface temperature in a global climate model for present and doubled CO2 climates",1992,"10.1175/1520-0442(1992)005<0920:SDRAVO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000457091&doi=10.1175%2f1520-0442%281992%29005%3c0920%3aSDRAVO%3e2.0.CO%3b2&partnerID=40&md5=2110f8a9ddd26182233eaf9922f943f7","The variability of surface temperature simulated by a global climate model with a simple mixed-layer ocean is analyzed. The simulated diurnal and seasonal ranges of temperature are compared with observation, as is the day-to-day and interannual variability of temperature. The qualitative changes in these quantities due to doubling atmospheric carbon dioxide concentration are also presented. The simulation of the seasonal cycle of surface temperature has a cold bias in much of the extratropics, including central Europe, even allowing for the difficulties in comparing grid-box surface temperatures with station temperature at screen height. The simulated diurnal range of temperature for present-day climate is similar to that observed, though the diurnal cycle in the model in midlatitudes is generally less than observed. On doubling CO2, the diurnal range over land decreases by 0.3°C whereas mean temperatures increase by 6.3°C (global averages over land). In CO2-doubling experiments with a one-dimensional radiative-convective model, atmospheric absorption by carbon dioxide and water vapor increases, reducing the solar heating at the surface, and surface evaporation increases faster with temperature than the transfer of sensible heat (due to the Clausius-Clapyeron relation), both of which tend to reduce the diurnal cycle. However, in the three-dimensional model, the diurnal cycle increases substantially where the snow line recedes, where the land surface becomes drier, or where there are substantial decreases in cloud cover. The diurnal cycle of surface temperature decreases where sea ice is replaced by open water because of the increase in thermal inertia of the surface. The simulated patterns of interannual standard deviation of surface temperature are in general agreement with observations, except in high latitudes in winter, where the model values are larger than the observed, and over the tropical oceans where model values are smaller than observed. The changes on doubling CO2 are generally small and not statistically significant. There are, however, reductions along the sea-ice margins in winter and increases in some regions of northern midlatitudes in summer. On doubling CO2, the general patterns of diurnal ranges and daily standard deviations of surface temperature change little, even though the changes in mean temperature are substantial and significant. © 1992 American Meteorological Society."
"6503868342;7402546593;7201914101;","An interactive hybrid expert system for polar cloud and surface classification",1992,"10.1002/env.3170030201","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984474620&doi=10.1002%2fenv.3170030201&partnerID=40&md5=c1c5bdbbd751d51ea823f7a2d4d72436","An interactive hybrid expert system is developed to classify polar scenes using AVHRR LAC imagery. A total of 183 spectral and textural signatures are generated from which the 20 “best” are chosen using the Sequential Forward Selection procedure. These 20 features are used to populate the working memory of the expert system. A probabilistic neural network is used as the inference engine to make probabilistic estimates of class membership. As part of the inference engine, a sophisticated outlier test is performed to provide a measure of classification confidence. During a session, the user is provided with an extensive set of on‐screen aids to assist in labelling. The user may modify the knowledge base by adding new samples to existing classes or by including new classes. The expert system provides confidence measures and a distance measure from the proposed class cluster centre. The interactive environment allows the user to test the impact of class labelling upon the knowledge base before new data is entered. For users working with very large datasets and very complex scenes, the integrity of the knowledge base is the primary concern. A bootstrap method is used to validate classification accuracy. On the basis of 100 bootstrap samples, an overall classification accuracy of 87% is achieved, with a standard deviation of 1%. The result is that much more accurate cloud classification in polar regions now can be made, which will aid us in our monitoring of global climate changes. Copyright © 1992 John Wiley & Sons, Ltd"
"7006307463;7003554118;7102634466;7101782191;","Human Modification of Global Biogeochemical Cycles",1992,"10.1016/S0074-6142(08)62699-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956796879&doi=10.1016%2fS0074-6142%2808%2962699-6&partnerID=40&md5=147c99b8ce36cd8da11d2b1acc7d4805","This chapter discusses the human modification of global biogeochemical cycles. Many biogeochemical and physical processes are involved in determining the climate of the Earth, and some of these are being significantly perturbed by human activity. The physical and chemical composition of the atmosphere determines the transmission, absorption, and reflection of incoming solar radiation and outgoing terrestrial radiation, and the resulting energy balance determines surface temperature. The biogeochemical cycles of sulfur—a crucial component of clouds and most aerosols—and of carbon and nitrogen, which form radiatively important trace gases, are central to the radiative properties of the atmosphere. The combustion of fossil fuels, and the consequent oxidation of nitrogen in combustion air has greatly modified the natural atmospheric cycles of C, N, and S. Although the change of atmospheric CO2 has little effect on the chemical composition of precipitation, sulfur- and nitrogen-containing acids have a major impact on the chemical composition of rain and snow. These acids in turn perturb the cycles of important minor elements, such as aluminum, through the weathering process in rocks and soils. © 1992 Academic Press, Inc."
"7406543625;","Mesoscale features observed in the Taiwan Mei-Yu season",1992,"10.2151/jmsj1965.70.1B_497","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0002051357&doi=10.2151%2fjmsj1965.70.1B_497&partnerID=40&md5=7cc6a561b31eb033d022d3772be553f7","Mei- Yu (Baiu in Japan) is a weather and climate phenomenon in the area of Japan, Taiwan, and subtropical China where the seasonal rainfall distribution reaches a peak in late spring and early summer due to the repeated occurrence of the Mei- Yu front. From the satellite pictures, the Mei- Yu front is usually accompanied by a nearly continuous cloud band with organized mesoscale convective systems (MCSs). To the south of the Mei-Y u front, a low-l evel jet (LLJ) is often observed and is closely related to the formation of MCSs and heavy rainfall events. As the Mei- Yu front approaches Taiwan, the front and the accompanying MCSs and LLJ tend to be affected by the mesoscale topography of Taiwan, the Central Mountain Range (CMR). Besides, the land-sea contrast coupled with island topography produces the land-sea breeze, the mesolow, and the island circulations which are important in modulating the local precipitation. In this paper, an overview of the current understanding of the structure and dynamics of the mesoscale features observed in the Taiwan Mei- Yu season is presented. Research results in the pre- TAMEX era as well as those derived from TAMEX program are discussed for the Mei- Yu front, the LLJ, the MCSs, the mesolow, the land-sea breeze, and the island circulations. © 1991, Meteorological Society of Japan."
"7005311892;","Effects of weather on the retrieval of sea ice concentration and ice type from passive microwave data",1992,"10.1080/01431169208904024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026614391&doi=10.1080%2f01431169208904024&partnerID=40&md5=a91335575a956eb9eeae94f13a69111a","Effects of wind, water vapour, and cloud liquid water on ice concentration and ice type calculated from passive microwave data are assessed through radiative transfer calculations and observations. These weather effects can cause overestimates in ice concentration and more substantial underestimates in multiyear ice percentage by decreasing polarization and by decreasing the gradient between frequencies. The effect of surface temperature and air temperature on the magnitudes of weather-related errors is small for ice concentration and substantial for multiyear ice percentage. The existing weather filter in the NASA Team Algorithm addresses only weather effects over open ocean; the additional use of local open-ocean tie points and an alternative weather correction for the marginal ice zone can further reduce errors due to weather. Ice concentrations calculated using 37 versus 18 GHz data show little difference in total ice covered area, but greater differences in intermediate concentration classes. Given the magnitude of weather-related errors in ice classification from passive microwave data, corrections for weather effects may be necessary to detect small trends in ice covered area and ice type for climate studies.primary data set for long-term analyses (see Gloersen and Campbell 1988 a), particular care must be taken to assess the potential sources and magnitudes of error that are introduced by factors such as weather effects and changes in surface condition. © 1992 Taylor & Francis Ltd."
"56277695700;7005399437;","Extracting spectral albedo from noaa-9 avhrr multiple view data using an atmospheric correction procedure and an expert system",1992,"10.1080/01431169208904038","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026614581&doi=10.1080%2f01431169208904038&partnerID=40&md5=86e172131612ba2c76b745f0cc2dc948","A 100 km × 200 km region of the Sahelian zone of Africa was chosen as the place to demonstrate a new method of extracting hemispherical reflectance (albedo) from directional satellite data. Five NOAA-9 AVHRR daytime scenes in band 1 (0-58-0-68 μm) were corrected for atmospheric variations to give the directional reflectances al the ground level. Using a stratification of the Gao region of Mali (Hiernaux 1989) based on soil texture, satellite data for homogeneous areas were selected. The number of view directions and the orientation of these varied because of the variable cloud cover and the changing orientation of the scanning radiometer with each overpass. These data were used in a knowledge-based expert system called VEG. This system is designed to handle a wide variety of kinds of input data. It contains an array of different techniques for inferring hemispherical reflectance. VEG accepted the spectral directional reflectance data, determined the best techniques for inferring spectral hemispherical reflectance, applied these to the selected sites and provided a rigorous estimate of the accuracy of the inference. VEG made all decisions and inferences using the input reflectance data and internal knowledge bases. The calculated directional reflectance factors at ground level were very similar to ground measurements reported in the literature. Furthermore, it was dear that a single nadir observation technique was always less accurate for estimating hemispherical reflectance than VEG using multiple view angles. The mean errors of the hemispherical reflectance of the entire region using VEG with multiple view angles and the direct nadir technique were 3 and 10 per cent, respectively, where the errors of the individual homogeneous areas were weighted by their relative sizes. © 1992 Taylor & Francis Ltd."
"7005635934;7004920873;","A global three-dimensional model of the tropospheric sulfur cycle",1991,"10.1007/BF00058134","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025919288&doi=10.1007%2fBF00058134&partnerID=40&md5=9dfc67e80d91b8d7708ce7250aed49cb","The tropospheric part of the atmospheric sulfur cycle has been simulated in a global three-dimensional model. The model treats the emission, transport, chemistry, and removal processes for three sulfur components; DMS (dimethyl sulfide), SO2 and SO42- (sulfate). These processes are resolved using an Eulerian transport model, the MOGUNTIA model, with a horizontal resolution of 10° longitude by 10° latitude and with 10 layers in the vertical between the surface and 100 hPa. Advection takes place by climatological monthly mean winds. Transport processes occurring on smaller space and time scales are parameterized as eddy diffusion except for transport in deep convective clouds which is treated separately. The simulations are broadly consistent with observations of concentrations in air and precipitation in and over polluted regions in Europe and North America. Oxidation of DMS by OH radicals together with a global emission of 16 Tg DMS-S yr-1 from the oceans result in DMS concentrations consistent with observations in the marine boundary layer. The average turn-over times were estimated to be 3, 1.2-1.8, and 3.2-6.1 days for DMS, SO2, and SO42- respectively. © 1991 Kluwer Academic Publishers."
"13303090800;","A study on the ecological climates of some famous tea growing areas in high mountainous regions of China",1991,"10.1007/BF02664508","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026302491&doi=10.1007%2fBF02664508&partnerID=40&md5=474c4d8a8ca568ce46861c3cf02f9788","The tea tree [Camellia sinensis (L) Kuntze] is one of the world's economic crops. It is an especially important crop for southern China. Environmental factors related to the tea yield and quality in some high mountain areas of China are identified in this paper. These factors are: geology, topography, climate, hydrology, soil and vegetation. Climatological factors are the most important. Using data collected from meteorological stations which are situated at the summit and the base of high mountains, this paper discusses ecological climatic problems in growing tea in China. The ecological climatic characteristics of the famous tea areas mainly included are as follows: more amounts of clouds and fog, less percentage of sunshine, abundant rainfall and high relative humidity in the air, temperatures that rise and fall slowly, daily and annual temperature ranges that are smaller, more days that are suitable for tea growing and low wind speeds in the lee-sides and valleys of mountains. All of these factors are favorable for growth of tea trees. © 1991 Science Press."
"6603239296;","Extremely low temperatures in the stratosphore and very low total ozone amount above northern and central Europe during winter 1989",1991,"10.1007/BF00114775","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025922221&doi=10.1007%2fBF00114775&partnerID=40&md5=f3216bc22e02d61a18baefed16e1107a","On 1 February 1989, -83.5°C was recorded in 27.8 hPa over Hohenpeißenberg, the lowest temperature in the 22-year series. This was measured together with a very low total ozone amount of 266 DU. This may be compared with nearly twice this amount on 27 February 1989. The situation was very unusual: following an extremely cold winter in the Arctic stratosphere, the stratospheric cold pole was located over southern Scandinavia on 1 February in a very southerly position. The analyzed temperatures of -92 °C in 30 hPa were also unusual. Even though the low ozone amounts over Hohenpeißenberg were probably dynamically caused, an additional very small ozone decrease due to heterogeneous reactions in altitudes from 23-28 km, where the temperatures lie below -80 °C, cannot be ruled out. Extinction measurements by the orbitting SAGE II instrument indeed show polar stratospheric clouds over Europe near 50° N during the period 31 January-2 February. Also, polar stratospheric clouds were previously observed over Kiruna at similarly low temperatures and signs of a corresponding small ozone decrease were noted there. © 1991 Kluwer Academic Publishers."
"7004689344;","The nature and significance of the feedback of changes in terrestrial vegetation on global atmospheric and climatic change",1991,"10.1007/BF00138995","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000848917&doi=10.1007%2fBF00138995&partnerID=40&md5=7384d21c1d34c751d59624a16e18a5c9","The potential feedback on global atmospheric and climate change of climate-driven changes in terrestrial vegetation is examined by systematically relating the surface exchanges of energy, mass and momentum to two dimensions of vegetation, structure and taxonomy, such that the significance of climate driven changes in these characteristics can be assessed. A detailed quantitative understanding of this feedback is an important prerequisite to realistic and dynamic representations of the Earth's surface within general circulation and biological models (GCMs and GBMs). Without realistic representations of terrestrial vegetation within these models, any forecasts of future climates by these models must be suspect. Several general conclusions are drawn. The first is that the indirect feedbacks, those associated with the clouds and aerosols of the planetary boundary layer, appear to be very powerful but as yet their behaviour and connections with the underlying surface are both poorly understood and captured within GCMs. The physical structure of vegetation, the disposition of biomass in 3-D, is the characteristic that most strongly influences the exchange of momentum (via aerodynamic roughness) and solar radiation (via albedo). Vegetation structure and species composition determine the most important of the mass exchanges, evapotranspiration. Of all of the surface exchanges, the parameterization of evapotranspiration (Eτ) and the simulation of the water balance over time is the most critical. Lastly, the problems of scaling and spatial heterogeneity, the sub-grid variability of the modellers, looms as a difficult, but not insoluble, problem. It remains a critical problem however, and the detailed parameterization of the various 'big leaf' models stands in absurd contrast to the simplistic generalization of the spatial heterogeneity of terrestrial landscapes. Plant ecologists can contribute to the task of improving the representation of vegetated landscapes within GCMs. There is need to simply and unify the way in which vegetation can be grouped at landscape scales. A classification that is based on function rather than phylogeny is required. The definition of Vegetation Functional Types (VFTs) would expedite research on both the impact of, and feedback on, climate change. © 1991 Kluwer Academic Publishers."
"6701652286;56744278700;7102875645;","A comparative study of the observations of high clouds and simulations by an atmospheric general circulation model",1991,"10.1007/BF00251805","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026269369&doi=10.1007%2fBF00251805&partnerID=40&md5=cb0752450ef51eb2afa9881647c31c1c","The importance of clouds in the upper troposphere (cirrus) for the sensitivity of the Earth's climate e.g., requires that these clouds be modeled accurately in general circulation model (GCM) studies of the atmosphere. Bearing in mind the lack of unambiguous quantitative information on the geographical distribution and properties of high clouds, the simulated distribution of upper tropospheric clouds in a spectral GCM is compared with several satellite-derived data-sets that pertain to high clouds only, for both winter and summer seasons. In the model, clouds are assumed to occupy an entire gridbox whenever the relative humidity exceeds 99%: otherwise the grid box is assumed to be free of cloud. Despite the simplicity of the cloud prediction scheme, the geographical distribution of the maxima in the model's upper tropospheric cloud cover coincides approximately with the regions of the observed maxima in the high cloud amount and their frequency of occurrence (e.g., intertropical convergence zone and the monsoon areas). These areas exhibit a minimum in the outgoing longwave radiation (OLR; Nimbus-7) and are also coincident with regions of heavy precipitation. The model, with its relatively simple cloud formation scheme, appears to capture the principal large-scale features of the tropical convective processes that are evident in the satellite and precipitation datasets, wherein the intense, upward motion is accompanied by condensation and the spreading of thick upper tropospheric layers of high relative humidity and cloudiness in the vicinity of the tropical rainbelt regions. © 1991 Springer-Verlag."
"6602274096;","Climate model sensitivity to sea ice albedo parameterization",1991,"10.1007/BF00865548","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0008329108&doi=10.1007%2fBF00865548&partnerID=40&md5=dc0d8aa801eba960020f3588c8c59687","Three one-year experimental simulations with the National Center for Atmospheric Research Community Climate Model (NCAR CCM) were performed with three sea ice albedo parameterizations and compared with control run results to examine their impact on polar surface temperature, planetary albedo and clouds. The first integration utilized sea ice albedos of the Arctic Basin for the spring and summer of 1977 derived from defence Meteorological Satellite Imagery (DMSP). The second simulation employed prescribed lead and melt pond fractions and an albedo weighting scheme. The third simulation involved the coupling of an interactive sea ice/snow albedo parameterization made a function of surface state. Results show that prescribed, and assumed ""true"" satellite sea ice albedos produced higher planetary albedos than those calculated with the standard CCM sea ice albedo scheme in the control run. As a result, lower temperatures (up to 0.5 K) and increased cloudiness are generated for the Arctic region. The standard CCM sea ice albedo scheme is used as an adjustment to maintain ""normal"" temperatures for the polar oceans. The radiative impact of leads and melt ponds warmed sea ice regions only for short time periods. The third scheme generated markedly lower planetary albedos (reductions of 0.07 to 0.17) and higher surface temperatures (up to 2.0 K) than control values. The CCM simulates a gradual decrease in spring and summer Arctic cloud cover whereas observations show a sharp spring increase. Examination of the CCM code, particularly the cloud parameterization, is required to address this problem. © 1991 Springer-Verlag."
"7202155374;7202257430;","Land surface hydrology in a General Circulation Model N-global and regional fields needed for validation",1991,"10.1007/BF01903414","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3743071130&doi=10.1007%2fBF01903414&partnerID=40&md5=67d97ca4d12df2f51523849d5776ff2a","Treatments of land surface processes in General Circulation Models are presently limited by the realism of the simulations of precipitation and surface radiation. We explore this thesis by examination of some of the climatological fields of a 6-year model simulation, using the Community Climate Model version 1 of the National Center for Atmospheric Research with addition of a diurnal cycle and coupled to a detailed treatment of land surface processes referred to as the Biosphere-Atmosphere Transfer Scheme. We examine July climatological surface fields over North America and note an excess of surface solar radiation over Eastern United States. Comparison with satellite derived cloud forcing suggests that the model underestimates the reduction of solar radiation by clouds over Eastern United States and in high latitudes, and so probably largely explaining the excess surface radiation. We consider the annual cycle of model hydrological fields (soil moisture, runoff, precipitation, evapotranspiration, net radiation) averaged over a box covering the central part of the United States (roughtly the Mississippi basin). The seasonal cycle of evapotranspiration over this box appears to be dominated by the variation of surface solar radiation and less related to that of precipitation. © 1991 Kluwer Academic Publishers."
"7005513582;","Clouds and climate change",1991,"10.1029/90EO00088","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84985773375&doi=10.1029%2f90EO00088&partnerID=40&md5=088ab99f3adddb1ca1632bb0d848ce50","As concern grows over the possibility of altering the Earth's climate, a major uncertainty exists in computer models used to study the Earth's atmosphere, regarding our current understanding of clouds and our ability to simulate their effect on climate. A number of recent observations and computer simulation studies, however, have shed light on the important role of clouds in determining the present and future climate of our atmosphere. Data from the National Aeronautics and Space Administration's (NASA's) Earth Radiation Budget Experiment have been used to obtain an accurate picture of how clouds affect our present global climate system [Ramanathan, 1989]. The effect of clouds on solar and thermal radiation entering and leaving our climate is known as cloud forcing. Low clouds generally cool the Earth's surface, while high clouds warm the climate system. For the entire planet, however, the cooling effect of low clouds is stronger than the warming effect from high clouds, so that overall, clouds cool the climate. ©1991. American Geophysical Union. All Rights Reserved."
"56627414400;","The radiative effects of clouds and their impact on climate",1991,"10.1175/1520-0477(1991)072<0795:TREOCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026272729&doi=10.1175%2f1520-0477%281991%29072%3c0795%3aTREOCA%3e2.0.CO%3b2&partnerID=40&md5=493593b479607c7a4416adf7318aa1de","There is general agreement that the annual global mean effect of clouds is to cool the climate system, but there is significant diasgreement on magnitude, with the two investigations based on recent satellite data indicating a range from 17 to 27 W/m2. Cold sensitivity, which represents the differential response of top-of-the-atmosphere fluxes to changes in cloud cover parameters, is a critical factor in cloud feedback. Two estimates, of the sensitivity to cloud amount, show wide discrepancies. To be useful, future studies of sensitivity will have to separate different cloud types. Sensitivity of clouds to cloud condensation nuclei raises the issue of a more direct role of clouds in climate change, where aerosols associated with SO2 emissions can ultimately lead to brighter clouds and a reduction in solar heating. -from Author"
"7004540083;","Use of operational satellite data for study of clouds and radiation in climate",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026312515&partnerID=40&md5=15e22cb521463b76f95f796c60d6bc7a","A brief summary is given of early results from the analysis of operational satellite data for the International Satellite Cloud Climatology Project. These data appear useful for studying the role that clouds play in determining the climate and its variations. -Author"
"7005882490;7006312044;16185051500;","Measurements of Aitken nuclei and cloud condensation nuclei in the marine atmosphere and their relation to the DMS-cloud-climate hypothesis",1991,"10.1029/91jd01870","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026313429&doi=10.1029%2f91jd01870&partnerID=40&md5=a3901782bcdc652b5fb8ebd1f0f3dab8","New airborne measurements provide support for the hypothesis that layers of high concentrations of Aitken nuclei near the tops of marine clouds are due to photochemical nucleation. They also reveal a significant correlation between cloud condensation nucleus (CCN) concentrations in the boundary layer and mean cloud droplet concentration in stratus clouds topping a marine boundary layer. Non sea salt sulfate mass and the concentration of CCN active at 1% supersaturation are also significantly correlated. These results provide quantitative support for some facets of the DMS-cloud-climate hypothesis. -Authors"
"7003696491;","Aerosol and climate-an overview",1991,"10.1016/0960-1686(91)90160-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025830840&doi=10.1016%2f0960-1686%2891%2990160-9&partnerID=40&md5=7ee3f345d0a592a0346950de24b2cffe",[No abstract available]
"7004540083;","Use of operational satellite data for study of clouds and radiation in climate",1991,"10.1016/0921-8181(91)90067-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949277168&doi=10.1016%2f0921-8181%2891%2990067-7&partnerID=40&md5=b7ca6f55dcd6cb92939a2205995badbf","A brief summary is given of early results from the analysis of operational satellite data for the International Satellite Cloud Climatology Project. These data appear useful for studying the role that clouds play in determining the climate and its variations. © 1991."
"7102019869;","Marine stratocumulus climatologies",1991,"10.1002/joc.3370110204","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026055524&doi=10.1002%2fjoc.3370110204&partnerID=40&md5=c7a6a05500700eb0d35081a72dc33120","Conditions favourable to the formation and maintenance of marine stratocumulus cloud decks commonly occur in the subtropical latitudes off the west coasts of the major continents. The cloud decks over the eastern North and South Pacific and the eastern South Atlantic are well‐established examples of the phenomenon; the eastern North Atlantic exhibits rather different behaviour. Large‐scale climatological averages based on data extracted from the Comprehensive Ocean‐Atmosphere Data Set are remarkably similar in the three of these regions that exhibit well‐established marine stratocumulus cloud decks. Off the coast of northwest Africa, however, the sea‐surface temperatures are higher and the cloud cover is less overcast than for the other regions. The correlation between interannual changes in clouds and SST is negative in all four areas: years with lower than normal SST tend to be more cloudy. The implication of this for climate system feedbacks is that these clouds have the potential to exert positive feedback in the climate system. A zero‐order estimate of the strength of this positive feedback suggests that it could be comparable to that due to water vapour in the atmosphere. Copyright © 1991 John Wiley & Sons, Ltd"
"57212896715;7004547261;","Clouds-radiation interactions in a general circulation model: impact upon the planetary radiation balance",1991,"10.1029/90JD01535","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026079479&doi=10.1029%2f90JD01535&partnerID=40&md5=81bf1994e65cf80cc6266ce08f5a54dd","The multimonth set of simultaneous Earth radiation budget observations and cloud amount estimates was used to validate a long-term climate simulation obtained with NCAR Community Climate Model. Although the global distributions of the seasonal average and standard deviation of the model-generated cloud and radiation fields agreed reasonably well with those obtained from satellite observations, the magnitude of the standard deviation of both fields was overestimated by about a factor of 2 over the whole globe. It is desirable to implement stronger couplings between the various physical processes in the NCAR Community Climate Model. -from Authors"
"7003830856;","Aerosols, clouds and radiation",1991,"10.1016/0960-1686(91)90159-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026278419&doi=10.1016%2f0960-1686%2891%2990159-5&partnerID=40&md5=fe1d3a88950757e3029fbf61e79acdfc","Most of the so-called 'CO2 effect' is, in fact, an 'H2O effect' brought into play by the climate modeler's assumption that planetary average temperature dictates water-vapor concentration (following Clapeyron-Clausius). That assumption ignores the removal process, which cloud physicists know to be influenced by the aerosol, since the latter primarily controls cloud droplet number and size. Droplet number and size are also influential for shortwave (solar) energy. The reflectance of many thin to moderately thick clouds changes when nuclei concentrations change and make shortwave albedo susceptible to aerosol influence. © 1991."
"7004034323;7003314664;","Response of the National Center for Atmospheric Research community climate model to improvements in the representation of clouds",1991,"10.1029/91jd00930","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026304180&doi=10.1029%2f91jd00930&partnerID=40&md5=1cfb9b7533c2b5cc9188e38fbb4530cc","The techniques employed to treat the contribution by water vapor absorption to the cloud radiative properties, the overlaps between cloud layers, and the spectral dependence of the properties are described, and comparisons are made with a more detailed radiation code. Only minor adjustments are necessary to implement the cloud prediction scheme. There are improvements in the model's temperature structure and in the radiation budget and cloud radiative forcing when compared with results from the Earth Radiation Budget Experiment. -from Authors"
"7102019869;","Cloud albedo control by cloud-top entrainment",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026014927&partnerID=40&md5=fe7ba4e133ae6e22339d128063c61105","Aircraft measurements of a stratocumulus cloud deck taken around local noon during the 1987 field phase of the First International Satellite Cloud Climatology Project Regional Experiment are the topic of this paper. A mixing line analysis of data from a series of flight tracks across a strong gradient in cloud albedo provides evidence that variations in the water vapor content of the air above the marine inversion can be responsible for the albedo change. The implications of this unexpected result for climate modeling are discussed. -from Author"
"56840368700;","Global climate, energy and water cycle",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026281925&partnerID=40&md5=4cc63b3ca0803324787993c2e7df132d","The Global Energy and Water Cycle Experiment (GEWAX) and Programme of the World Climate Research Programme will include a series of process studies of land surfaces and hydrology and of clouds and radiation, global data collection projects for clouds, radiation and precipitation and numerical modelling, leading to a global observing experiment in the late 1990s. -from Author"
"7007026915;","Satellite remote sensing in climatology",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040896636&partnerID=40&md5=7e757dbb8d1aee185f5dd8cf43083e01","Adopts a thematic approach to explaining contemporary concepts of weather and climate processes using satellite remote sensing data. Particular emphasis is placed on the role of clouds in climate; climatic teleconnections and surface-atmosphere interaction; and large-scale features of the general circulation, such as vortices and cloud bands. The importance of satellite information is discussed in relation to the development of baseline regimes of climatically-significant variables, and the monitoring of departures from those regimes as evidence of climatic anomolies and trends. Topics associated with those changes include the El Nino Southern Oscillation phenomenon; polar sea ice variations; and global warming. In addition, the author describes the role of satellite monitoring of impacts related to human activity on the climate system, through stratospheric ozones depletion, deforestation, desertification, and cloud cover augmentation. -after Publisher"
"57199134730;","Historical records of cloud cover and climate for Australia",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026365573&partnerID=40&md5=3bf7b35fd1eef1a6474a27907f58106d","Analyses show a close correlation between precipitation and cloud cover and an inverse correlation between the diurnal temperature range and cloud cover. Significant long-term trends are evident in the data, with an increase in cloud cover and a decrease in the diurnal temperature range. There is also a slight increase in daily mean temperature, but no significant long-term change in precipitation (although the lack of significant trend may, in part, be due to the shorter length of record). The fluctuations in cloud cover, diurnal temperature range and precipitation are correlated with the SOI. Correlations of cloud cover with SOI are strongest for the northeast and weakest for the southwest of the continent. -from Author"
"7005882490;7004546686;16185051500;7006312044;","Dimethyl sulfide and cloud condensation nucleus correlations in the northeast Pacific Ocean",1991,"10.1029/91jd01309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026304367&doi=10.1029%2f91jd01309&partnerID=40&md5=5b59677a6503d43b9cbbd6ea7955e5fe","A regression analysis on measurements of cloud condensation nucleus (CCN) and dimethyl sulfide (DMS) concentrations in the boundary layer over the northeastern Pacific Ocean shows these two parameters to be highly correlated. This complements and supports coherent seasonal trend data on DMS and CCN concentrations obtained at Cape Grim, Tasmania. The correlation between CCN and DMS at both northern and southern hemispheric remote marine sites, provides empirical support for the DMS-cloud-climate hypothesis. A possible nonlinear relationship between DMS and size-segregated CCN concentrations is suggested by the data. -Authors"
"7402873051;57210518852;7003666669;","Planktonic dimethylsulfide and cloud albedo: An estimate of the feedback response",1991,"10.1007/BF00142502","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0003373307&doi=10.1007%2fBF00142502&partnerID=40&md5=a06ddae27c3f6bea7f7d1055e5ca5175","Partial control of climate by the biosphere may be possible through a chain of processes that ultimately links marine plankton production of dimethylsulfide (DMS) with changes in cloud albedo (Charlson et al., 1987). Changes in cloud optical properties can have profound impacts on atmospheric radiation transfer and, hence, the surface environment. In this study, we have developed a simple model that incorporates empirically based parameterizations to account for the biological control of cloud droplet concentration in a first attempt to estimate the strength of the DMS-cloud albedo feedback mechanism. We find that the feedback reduces the global climatic response to imposed perturbations in solar insolation by less than 7%. Likewise, it modifies the strength of other feedbacks affecting surface insolation over oceans by roughly the same amount. This suggests that the DMS-cloud albedo mechanism will be unable to substantially reduce climate sensitivity, although these results should be confirmed with less idealized models when more is known about the net production of DMS by the marine biosphere and its relation to aerosol/cloud microphysics and climate. © 1991 Kluwer Academic Publishers."
"7005513582;7402435469;","Dependence of cloud amount on horizontal resolution in the National Center for Atmospheric Research Community Climate Model",1991,"10.1029/91jd00164","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026266396&doi=10.1029%2f91jd00164&partnerID=40&md5=ebe54899ef5aa069d2d5415387be7ead","Using R15, T42, T63 and T106 versions of the CCM, we find that the total cloud amount monotonically decreases with increased horizontal resolution. This decrease is particularly evident in the low-level cloud associated with stable condensation in the tropics. Decreases in low-level and upper-level extratropical clouds with increased resolution are also apparent. Analysis of these model simulations shows that this decrease is due to increased advective drying of the lower atmosphere by stronger subsidence. Stronger upward motion which is directly associated with stronger heating in the convergence region by moist convective adjustment and stable condensation processes is also apparent with increased horizontal resolution. -from Authors"
"7005171879;","The polarization lidar technique for cloud research: a review and current assessment",1991,"10.1175/1520-0477(1991)072<1848:TPLTFC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026300982&doi=10.1175%2f1520-0477%281991%29072%3c1848%3aTPLTFC%3e2.0.CO%3b2&partnerID=40&md5=b3b8ee59a9158e8f1673f675ef3f4498","Polarization lidar is a key component of current climate-research programs to characterize the properties of cirrus clouds, and is an integral part of multiple remote-sensor studies of mixed-phase cloud systems, such as winter mountain storms. New results simulating the single and multiple scattering properties of precipitating mixed-phase clouds are given for illustration of such methods. -from Author"
"7402565763;","Observations of anthropogenic cloud condensation nuclei",1991,"10.1016/0960-1686(91)90162-Z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026290882&doi=10.1016%2f0960-1686%2891%2990162-Z&partnerID=40&md5=9dda9f64d807293bbc0f3b262110a661","Cloud condensation nuclei (CCN) concentrations and spectral measurements obtained with the DRI instantaneous CCN spectrometer (Hudson, 1989, J. atmos. ocean. Technol. 6, 1055-1065) are presented. Anthropogenic CCN production mechanisms were readily identifiable while natural CCN production could not be detected. © 1991."
"7005955015;","Cloud parametrization at different horizontal resolutions",1991,"10.1002/qj.49711750207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026360462&doi=10.1002%2fqj.49711750207&partnerID=40&md5=87defc40d1f2ed9b1a73b8caab0fca7b","As faster computers emerge, resolution continues to improve in weather‐prediction and climate models. How does this affect the problems that we are dealing with in the models? In this study we have concentrated on one of these problems, namely the treatment of clouds. Among the questions addressed are: How do cloud‐related processes (condensation, precipitation) depend on grid resolution? How should we take this into account? Can we simulate orographic clouds when we have a grid resolution of hundreds of kilometres (climate models)? To tackle these questions simulations are performed with a limited‐area model that is run with horizontal grid resolutions of 150,50 and 25 km. The model has a sophisticated treatment of condensation and clouds. For verification, use is made of satellite‐derived cloud water content and cloud cover, and surface observations of precipitation. It is found that when resolution is enhanced, precipitation systematically increases while cloud cover decreases. The main reason is that much stronger vertical motions develop at high resolution, yielding dense, narrow clouds, with clear air between. The consequences of these results for cloud parametrization are discussed. It is further shown that cloud‐cover simulations over mountainous terrain can be improved by paying regard to the sub‐grid‐scale orography. Copyright © 1991 Royal Meteorological Society"
"7003601758;","Cloud motion winds from Meteosat: performance of an operational system",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026268242&partnerID=40&md5=da361bb58f6407d4cdb4936f8af4f27d","Wind fields have been estimated from the displacement of clouds in successive Meteosat infrared (IR: 10.5-12.5μm) images for more than a decade. The derivation of cloud motion winds (CMW) works fully automatically. In this paper the improvements to the CMW derivation from Meteosat images are described. In particular the height assignment of a wind vector and radiance filtering techniques preceding the cloud tracking have ameliorated the errors in Meteosat winds significantly. The low speed bias of high level CMWs (<400 hPa) in comparison with radiosonde winds has been reduced by more than 60% since 1987. This has significantly enhanced the usefulness of CMWs for the global analysis/forecast systems and hence their potential for climate diagnostic studies. -from Author"
"6603928917;","Climate monitoring using an AVHRR-based vegetation index",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026287188&partnerID=40&md5=c8da3df07da143b629c0dbfa32fe3756","A normalized difference vegetation index (NDVI) has been produced and archived on a 1° latitude by 1° longitude grid between 55°S and 75°N. There are many sources of data errors in the NDVI including cloud contamination, scan angle biases, changes in solar zenith angle, and sensor degradation. Week-to-weeek variability is primarily caused by cloud contamination and scan angle biases and can be minimized by temporally filtering the data. Orbital drift and sensor degradation introduces interannual variability into the dataset. -from Author"
"57198124502;24356192500;8290769700;","Operational production of winds from cloud motions",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026311641&partnerID=40&md5=1e84166a7ccab5370ba82de7249aa90d","Operational production of NOAA cloud motion winds is reviewed. A new technique to improve the height assignment of the cloud motion winds is described and statistical verification of satellite wind information is discussed. Higher quality satellite wind data are a valuable tool to improved descriptions of global atmospheric circulation, which is an important constituent in studies of climate and global change. -Authors"
"7006689276;","Remote sensing and global climate change: water cycle and energy budget",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026289921&partnerID=40&md5=e3ca47ba6d9f0cd2396b7a9f8865abeb","The next section summarizes satellite remote sensing achievements with respect to water cycle components and net radiation budget at the top of the atmosphere and also points to the main gaps. A logical approach seems to be the start from water vapour column content to water vapour profiles, clouds, ocean surface temperature, ocean topography, sea level, sea ice, snow cover and ice caps, before the final section discusses the radiation budget at the top of the atmosphere and the clouds' role in this budget. -from Author"
"6603945698;","Hints of another gremlin in the greenhouse: anthropogenic sulfur",1991,"10.1016/0960-1686(91)90164-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026268225&doi=10.1016%2f0960-1686%2891%2990164-3&partnerID=40&md5=76fb2bb35c842ebf530071104da6a2cd","Already there are many complicating factors ('gremlins') that frustrate attempts to link observed climate changes to predictions from the greenhouse hypothesis. Consequences of these 'gremlins in the greenhouse' (along with their possible identities) include hemispherically asymmetric cooling of the lower stratosphere (perhaps caused by asymmetric ozone destruction by chlorofluorocarbons), cooling of the tropical upper troposphere (perhaps caused by an increase in water vapor), lack of polar amplification of lower tropospheric warming (poorly modeled clouds, ocean currents, ice and snow et al.), and asymmetric warming of the lower tropospheres of the two hemispheres (differences in thermal inertias, responses to volcanic eruptions et al.). In this report, emphasis is on examining hints that the cause of the relative cooling of the Northern Hemisphere has been anthropogenic sulfur emission; it is concluded that this concept is not inconsistent with the data; however, the possibility that all observed temperature changes are natural is also not inconsistent with the data. Research needed to remove these ambiguities includes more extensive monitoring, improvements to climate models, advances in statistical analyses of time series, better definition of climatic consequences of volcanic eruptions, and focused efforts to understand and describe the major climate changes that occurred in the Northern Hemisphere c. 1940 and 1815. © 1991."
"57198124502;24356192500;8290769700;","Operational production of winds from cloud motions",1991,"10.1016/0921-8181(91)90084-A","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949276094&doi=10.1016%2f0921-8181%2891%2990084-A&partnerID=40&md5=ba376cd959fbbac5ddad483ddb3a163e","Operational production of NOAA cloud motion winds is reviewed. A new technique to improve the height assignment of the cloud motion winds is described and statistical verification of satellite wind information is discussed. Higher quality satellite wind data are a valuable tool to improved descriptions of global atmospheric circulation, which is an important constituent in studies of climate and global change. © 1991."
"7006393951;","New assessments of global climate change",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026302244&partnerID=40&md5=a100d18608cd10aab9be6cd222a308bc","A consensus has been reached on one of the most important conclusions that the causes of the climate warming observed during the last century remain still unclear. This determines the top urgency of studies and quantitative assessments of the internally forced variability of the climate system, without which the ""filtering-out' of anthropogenic impacts on climate cannot be reliable. Such insufficiently studied factors of climate formation as ocean-atmosphere and cloud-radiation interactions are the most substantial aspects of the internal variability. -from Author"
"6701607011;7004540083;","Time-cumulated visible and infrared radiance histograms used as descriptors of surface and cloud variations",1991,"10.1080/01431169108929702","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026359732&doi=10.1080%2f01431169108929702&partnerID=40&md5=bc285af708c9afb151ab0e49b42df4ff","The spatial and temporal stability of the distributions of satellite-measured visible and infrared radiances, caused by variations in clouds and surfaces, are investigated using bidimensional and monodimensional histograms and time-composite images. Similar analysis of the histograms of the original and time-composite images provides separation of the contributions of the space and time variations to the total variations. The variability of both the surfaces and clouds is found to be larger at scales much larger than the minimum resolved by satellite imagery. This study shows that the shapes of these histograms are distinctive characteristics of the different climate regimes and that particular attributes of these histograms can be related to several general, though not universal, properties of clouds and surface variations at regional and synoptic scales. There are also significant exceptions to these relationships in particular climate regimes. The characteristics of these radiance histograms provide a stable well defined descriptor of the cloud and surface properties. © 1991 Taylor & Francis Ltd."
"7202208382;6603533215;","Clouds, the Earth's radiation budget, and the hydrologic cycle",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026290994&partnerID=40&md5=092104889d23534ccce124061102e5c1","Water vapor plays a key role in climate change scenarios through the water vapor feedback loop. The distribution of water vapor obviously controls the distribution of clouds, but the opposite is also true because clouds carry out important vertical redistributions of the vapor. This paper presents comparisons of water vapor observations with general circulation model simulations of the distribution of water vapor and its effects on the Earth's radiation budget. The ability of the model to simulate the seasonally changing cloud radiative forcing is also discussed. -from Authors"
"57189585133;7006307463;","Geophysiology of natural marine sulfate aerosols",1991,"10.1016/0960-1686(91)90161-Y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025823604&doi=10.1016%2f0960-1686%2891%2990161-Y&partnerID=40&md5=bb13da1be4277418ad5d4264edc277c3","The hypothesis suggesting dimethyl sulfide (DMS) from oceanic phytoplankton as the dominant natural worldwide source of cloud condensation nuclei (CCN) is being tested in several ways. Studies ranging from the perturbation of cloud albedo by ship plumes to the sulpur content of Antarctic ice cores have revealed much about the workings of the natural marine sulfur cycle and the mass flux of DMS-derived sulfur compounds. However, quantifying the relationship between DMS mass flux, or sulfate mass concentration, and CCN number remains as a major challenge. © 1991."
"7005293830;7004423756;","Derivation of long-term climate data sets from NOAA's HIRS2/MSU",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026268239&partnerID=40&md5=69b9d855001d783d20cbe805c683c950","The High Resolution Infrared Sounder and the Microwave Sounding Unit (HIRS2/MSU) observations readily offer a unique opportunity to establish a global self-consistent data set of more than ten climate parameters extending over a decade in time. A retrieval package to extract geophysical parameters from the combination of infrared and microwave data returned since December 1978 from the NOAA weather satellites has been developed. The retrieval algorithm is an interactive forecast-retrieval-assimilation system based on the relaxation method of solution of the radiative transfer equation. The resulting climate data sets include: atmospheric temperature profiles, atomspheric humidity profiles, ocean surface temperature, land surface temperature, infrared cloud cover, cloud-top height and temperature, snow and ice cover, outgoing long-wave radiation, total ozone distribution, and rainfall rate index. -from Authors"
"7403208367;","Preliminary study of coupled oxidation-reduction reactions of included ions in growing ice crystals",1991,"10.1016/0960-1686(91)90216-T","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026043982&doi=10.1016%2f0960-1686%2891%2990216-T&partnerID=40&md5=2d8a33a614b22875208b58dd8c5cd08a",[No abstract available]
"7202208382;6603533215;","Clouds, the earth's radiation budget, and the hydrologic cycle",1991,"10.1016/0921-8181(91)90063-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949277977&doi=10.1016%2f0921-8181%2891%2990063-3&partnerID=40&md5=ad91717b4907495bd722cf16b04341af","Water vapor plays a key role in climate change scenarios through the water vapor feedback loop. The distribution of water vapor obviously controls the distribution of clouds, but the opposite is also true because clouds carry out important vertical redistributions of the vapor. This paper presents comparisons of water vapor observations with general circulation model simulations of the distribution of water vapor and its effects on the Earth's radiation budget. The ability of the model to simulate the seasonally changing cloud radiative forcing is also discussed. Finally, the need for long-term monitoring of these fields is emphasized. © 1991."
"7102019869;","Cloud albedo control by cloud‐top entrainment",1991,"10.1034/j.1600-0870.1991.00004.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981673126&doi=10.1034%2fj.1600-0870.1991.00004.x&partnerID=40&md5=5e105670564dd4ad50abecbf57de4500","Marine stratus and stratocumulus clouds exert a considerable influence on the Earth's heat budget, mainly due to their high albedos relative to the ocean surface. It is therefore important to understand the processes that control the radiative properties of these extensive cloud systems, particularly during daylight hours. Aircraft measurements of a stratocumulus cloud deck taken around local noon during the 1987 field phase of the First International Satellite Cloud Climatology Project Regional Experiment are the topic of this paper. A mixing line analysis of data from a series of flight tracks across a strong gradient in cloud albedo provides evidence that variations in the water vapour content of the air above the marine inversion can be responsible for the albedo change. The implications of this unexpected result for climate modelling are discussed. Copyright © 1991, Wiley Blackwell. All rights reserved"
"7102604282;7005716370;","Global climatic effects of aerosols: The AAAR symposium-An overview",1991,"10.1016/0960-1686(91)90158-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025868458&doi=10.1016%2f0960-1686%2891%2990158-4&partnerID=40&md5=6b373c1cbc9017764df8c80215a67f60",[No abstract available]
"7003899619;","Cloud and aerosol products at NOAA/NESDIS",1991,"10.1016/0921-8181(91)90066-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949277753&doi=10.1016%2f0921-8181%2891%2990066-6&partnerID=40&md5=053b73e4ebc768e5977d83a6ed5065d4","Global observations of cloud and aerosol properties from satellites are needed to understand the role of these atmospheric constituents in climate change, e.g. their radiative forcing and feedback effects and trends in their optical and physical characteristics. NOAA/NESDIS has developed remote sensing techniques as a means of providing these global measurements. As a by-product of our atmospheric sounding programs, TOVS and VAS infrared window and CO2 absorption band measurements are used to determine an ""effective"" cloud amount and cloud top pressure. Cloud liquid water content is being derived from DMSP/SSMT data. AVHRR data are used to derive total cloud amount. AVHRR data are also used to estimate aerosol optical thickness over the oceans. A brief description of the retrieval methods and their verification will be given, as well as several examples of these products. © 1991."
"6603928917;","Climate monitoring using an AVHRR-based vegetation index",1991,"10.1016/0921-8181(91)90093-C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949277669&doi=10.1016%2f0921-8181%2891%2990093-C&partnerID=40&md5=00510a60ef1c41639d7e278f3a53c1f1","A normalized difference vegetation index (NDVI) has been produced and archived on a 1° latitude by 1° longitude grid between 55° S and 75° N. There are many sources of data errors in the NDVI including cloud contamination, scan angle biases, changes in solar zenith angle, and sensor degradation. Week-to-week variability is primarily caused by cloud contamination and scan angle biases and can be minimized by temporally filtering the data. Orbital drift and sensor degradation introduces interannual variability into the dataset. These trends make the usefulness of a long-term climatology uncertain and limit the usefulness of the NDVI. Elimination of these problems should produce an index that can be used for climate monitoring. © 1991."
"7402565763;6506828940;","Surface cloud condensation nuclei and condensation nuclei measurements at Reno, Nevada",1991,"10.1016/0960-1686(91)90104-F","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026309325&doi=10.1016%2f0960-1686%2891%2990104-F&partnerID=40&md5=629d7e16c013c3930fcd25e36cbae016","Surface aerosol measurements from a moderately populated high mountain valley are interpreted in terms of local wind velocity and meteorology. Diurnal trends are apparent with light winds and especially during wintertime temperature inversions when the concentrations are dominated by local anthropogenic sources. Under conditions of higher wind speeds when the surface concentrations appear to be representative of widespread areas, a seasonal trend is revealed. Cloud condensation nuclei (CCN) concentrations are much higher during the late spring (&gt; 1000 cm-3) than during the winter (&lt; 400 cm-3) but the condensation nuclei (CN) concentrations are not seasonal. The seasonality of the CCN is probably caused by differences in the long range transport of particles from distant California population centers. © 1991."
"57203400519;","Atmospheric radiation",1991,"10.1002/rog.1991.29.s1.56","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026286276&doi=10.1002%2frog.1991.29.s1.56&partnerID=40&md5=8b64355776d8970c026146dd7be6c1c0","The topics to be covered have been classified (somewhat arbitrarily) into the following five categories although there is obviously considerable overlap among them. These are: i) Radiation Modelling; ii) Clouds and Radiation; iii) Radiative Effects in Dynamics and Climate; iv) Radiation Budget and Aerosol Effects; v) Gaseous Absorption Particulate Scattering and Surface Reflection. The bibliography accompanying this review has also been separated by topic although some papers have undoubtedly been misclassified. -from Author"
"6603896143;6506441620;","Advertent/inadvertent effect on 'rainfall center' displacement in Northern Israel",1991,"10.1016/0957-1272(91)90002-V","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026282664&doi=10.1016%2f0957-1272%2891%2990002-V&partnerID=40&md5=5017aa4d36b7e4cfb88f88b76b81b927","This study of cloud seeding and urbanization effects on the spatial rainfall distribution was carried out in two stages. In the first stage the location of a 'rainfall center' (the area with the rainfall maximum) for annual amounts of rainfall was established by applying the Distance Correlation Matrix (DISTCORMAT) technique. Besides 'natural' climatic fluctuations there are two other factors which could also cause a shift in the 'rainfall center', namely, cloud seeding operations and the inadvertent urban influences. Rainfall centers were computed for the two experimental cloud seeding periods and for a subsequent period of operational seeding. Comparison of the DISTCORMAT outputs revealed that the 'rainfall centers' are located, as expected, in the Upper Galilee for the first experimental period and later were displaced westward by 2-4 km. Since in the second random experiment the seeding flight route and target area were shifted eastward, it seems that there is no evidence supporting the cloud seeding rainfall excess determined by various statistical methods. However, it is possible to attribute the center's displacement to the massive urbanization process along the Mediterranean coastal plane. In the second stage only 40 rain stations in the extreme northern part of the country were used and the DISTCORMAT was computed separately for 'seeded days' and 'non-seeded days'. The results indicate that, although the center moved eastward on 'seeded days' during the second experiment, it moved westward for the 'non-seeded days' sample. Thus the finding offers evidence of both effects: advertent cloud seeding and the inadvertent urbanization factor. © 1991."
"7006705919;7402435469;","The sensitivity of a general circulation model climate to the moisture transport formulation",1991,"10.1029/91jd01179","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026273022&doi=10.1029%2f91jd01179&partnerID=40&md5=97c6bcdaf16827643a56ab9afcb75324","We compare two versions of the model, one of which uses a spectral method and the other a shape-preserving semi-Lagrangian method for the water vapor transport. These differences in climate result primarily from the redistribution of water vapor in the model. The redistribution carried with it differences in convection and cloud distributions and the associated radiative heating, which in turn affects the model climate. Some of the changes produced by changing from spectral to semi-Lagrangian transport are beneficial (that is, the model climate is closer to observations), and some are detrimental. We examine many of the pertinent feedback loops and diagnose the processes associated with the changed climate. -from Authors"
"6507735399;","An energy balance climate model with hydrological cycle 1. Model description and sensitivity to internal parameters",1991,"10.1029/91jd01478","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026299354&doi=10.1029%2f91jd01478&partnerID=40&md5=0023b414e3526931f3d9522368263c59","A thermodynamical model designed to illustrate the effect of a hydrological cycle on climate sensitivity is presented. The model contains three climatic variables; two temperatures referring to an idealized atmosphere and ocean, respectively, and atmospheric humidity. The independent variables are time and latitude. Atmosphere and ocean are coupled by radiation and convection at their interface. The sensitivity of the model is governed by radiation parameters. Of these, the cloud albedo is the most sensitive quantity. By contrast, the model is relatively little affected by parameters associated with horizontal and vertical transport of heat. -from Author"
"7003677647;7003353524;","Climatic atlas of the Delaware River Basin",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026273966&partnerID=40&md5=d9b9d8b2a15d037b71153bf667362195","The Delaware River basin is a diverse physiographic, hydrologic, and climatic region. The Delaware River serves as a major source of water for nearly 20 million people both in and outside the basin. Questions associated outside the variability of climate, the potential for climate change, and attendant implications for water resources and supply across this region in the coming decades require that there first be an appraisal of current climate conditions. To this end, graphs and maps for average monthly, seasonal, and annual values of temperature and precipitation across the basin during the period 1950-79 have been compiled in atlas form. Additional variables, including water budget terms, drought, cloud cover, hurricanes, and others have also been graphed and mapped. -Authors"
"7004345429;","Meteorology",1991,"10.1007/978-94-011-2904-6_7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026267544&doi=10.1007%2f978-94-011-2904-6_7&partnerID=40&md5=34d65a52406bbee7c8cc22a0f15f9057","The present paper will, therefore, concentrate on problems related to climate and climate change, and within this general area, on the greenhouse effects. A comparison will be made between the results of model studies and studies of the available climatological data with the major conclusion that, so far it has not been possible to create a direct link between the steadily increasing concentration of the greenhouse gases, particularly carbon dioxide, and the observed changes of temperature at the surface of the Earth. On the other hand, data from the upper atmosphere seems to indicate that the greenhouse gases may have had an effect on the temperatures above the major cloud layers and especially in the lower stratosphere. -from Author"
"7003984663;6603889543;","Influence of the trade-wind inversion on the climate of a leeward mountain slope in Hawaii",1991,"10.3354/cr001207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026299549&doi=10.3354%2fcr001207&partnerID=40&md5=3aad295f846362a744ef8313c0b4fbbc","Solar radiation, net radiation, air temperature, humidity, and wind measurements were taken along a transect on the leeward slope of Haleakala, Maui. Measurements indicate that the climate of Haleakala can be described with reference to 4 zones: a marine zone, below about 1200 m, of moist well-mixed air in contact with the oceanic moisture source; and fog zone found approximately between 1200 and 1800 m, where the cloud layer is frequently in contact with the surface; a transitional zone, from about 1800 to 2400 m, with a highly variable climate; and an arid zone, above 2400 m, usually above the inversion where air is extremely dry due to its isolation from the oceanic moisture source. -from Authors"
"7402456930;7005380343;","Variations in boundary layer properties associated with clouds and transient weather disturbances at the South Pole during winter",1991,"10.1029/90JD02605","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026290562&doi=10.1029%2f90JD02605&partnerID=40&md5=2ba6ed1003ff110a4f23df9e4b368ad6","Mean winter temperature and wind profiles for clear and overcast conditions are combined with surface radiation measurements and synoptic circulation patterns to study the mechanisms that cause periodic weakening of the inversion. Results support previous studies that ascribe this weakening to (1) warm air advection, (2) downward vertical mixing of sensible and latent heat, and (3) longwave cloud radiative heating. The integrity of the inversion depends on the combined effects of all three mechanisms. Parameters representing the intensity of the inversion and the bulk wind shear through the lower troposphere are suggested as appropriate indices for the detection of climate change in the region of the Antarctic Plateau. -from Authors"
"7003314664;7004034323;","The response of a general circulation model to cloud longwave radiative forcing. II: Further studies",1991,"10.1002/qj.49711749805","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026299160&doi=10.1002%2fqj.49711749805&partnerID=40&md5=30d56f07af98e30c3d7edc284b939056","Following on from the first part of this study, the impact of cloud longwave forcing on the general circulation has been studied further using a series of 510‐day, constant January integrations with the NCAR Community Climate Model. The sensitivity of the global response to the vertical profile of the forcing has been assessed by replacing the cloud prediction scheme by that used in the ECMWF model. The results confirm those reported in Part I and emphasize the influence of tropical cirrus clouds on the local thermal structure and on the strength of the subtropical jets. The impact on the model's hydrological cycle of the cloud longwave forcing associated with boundary‐layer clouds is also shown to be important. Several integrations are described which assess the relative importance of the three major tropical forcing maxima over Indonesia, South Africa and South America in determining both the local and remote responses. For each region, the perturbation to the upper tropospheric diabatic heating by the radiative effects of the cirrus clouds excites an anticyclonic vorticity pair, located near the longitude of the forcing and almost symmetric about the equator. The influence of these anticyclones on the upper tropospheric circulation is substantial. The results also indicate that a perturbation to the diabatic heating over South America, provided in this case by the cloud longwave forcing, may have an important effect on the Walker circulation and on the extra‐tropical flow. The implications of these results for the problem of deforestation are discussed. Copyright © 1991 Royal Meteorological Society"
"6701607011;7004540083;","Effects of satellite data resolution on measuring the space/time variations of surfaces and clouds",1991,"10.1080/01431169108929703","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026359730&doi=10.1080%2f01431169108929703&partnerID=40&md5=8bd4893094e5a76f9419d765500f66f6","The correlated distributions of satellite-measured visible and infrared radiances, caused by spatial and temporal variations in clouds and surfaces, have been found to be characteristic of the major climate regimes and can be described by the attributes of bidimensional and monodimensional histograms and time-composite images. Most of the variability of both the surfaces and clouds is found to occur at scales larger than the minimum resolved by satellite imagery. Since satellite imaging data sets are difficult to analyse because of their large volumes, many studies reduce the volume by various sampling or averaging schemes. The effects of data resolution and sampling on the radiance histogram statistics and on the time-composite image characteristics are examined. In particular, the sampling strategy used by the International Satellite Cloud Climatology Project is tested. This sampling strategy is found to preserve the statistics of smaller cloud variations for most regions, with the exception of very rare events, if they are accumulated over large enough areas (at least 500 km in dimension) and long enough time periods (at least one month). © 1991 Taylor & Francis Ltd."
"7003601758;","Cloud motion winds from METEOSAT: performance of an operational system",1991,"10.1016/0921-8181(91)90085-B","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949275526&doi=10.1016%2f0921-8181%2891%2990085-B&partnerID=40&md5=557d875f7c3d5aa45a5236e863120a33","Wind fields have been estimated from the displacement of clouds in successive METEOSAT infrared (IR: 10.5-12.5 μm) images for more than a decade. The derivation of cloud motion winds (hereafter: CMW) workss fully automatically, man-machine interaction is only performed as the very last step of manual quality control. At present about 3000 wind vectors per day are produced with four production runs and disseminated via the Global Telecommunication System (GTS) mainly for use in the analysis for numerical weather prediction. In this paper the improvements to the CMW derivation from METEOSAT images are described. In particular the height assignment of a wind vector and radiance filtering techniques preceding the cloud tracking have ameliorated the errors in METEOSAT winds significantly. The low speed bias of high level CMWs (< 400 hPa) in comparison with radiosonde winds has been reduced by more than 60% since 1987. This has significantly enhanced the usefulness of CMWs for the global analysis/forecast systems and hence their potential for climate diagnostic studies. © 1991."
"7003931528;7003979342;6603242611;55275125900;","Tracer transport in the Hamburg climate model",1991,"10.1007/978-1-4615-3720-5_44","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026305663&doi=10.1007%2f978-1-4615-3720-5_44&partnerID=40&md5=7259a8679073335532987f192f02959f","Transport of tracers by advection, vertical diffusion and shallow convection is treated similarly to the transport of water vapor. A new scheme was developed for vertical mixing in deep convective clouds consistent with the Kuo-scheme used in the GCM. In order to investigate the large scale transport and the interhemispheric exchange simulation runs were performed with the chlorofluorocarbon F11. The short-lived radioactive rare gas 222Radon was used to demonstrate the role of subgrid scale processes in the dispersal of tracers. There is a short general discussion at the end of the article. -from Authors"
"7005293830;7004423756;","Derivation of long-term climate data sets from NOAA's HIRS2/MSU",1991,"10.1016/0921-8181(91)90081-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949276286&doi=10.1016%2f0921-8181%2891%2990081-7&partnerID=40&md5=563328009bc09001d00a8c836a21fcfc","Accurate long-term global data sets are essential for achieving better understanding of the Earth's climate system and for modelling its complex interactions and feedback mechanisms. The High Resolution Infrared Sounder and the Microwave Sounding Unit (HIRS2/MSU) observations readily offer a unique opportunity to establish a global self-consistent data set of more than ten climate parameters extending over a decade in time. Such a data set would add considerably to our current information. To this end, we have developed and tested a retrieval package to extract geophysical parameters from the combination of infrared and microwave data returned since December 1978 from the NOAA weather satellites. The retrieval algorithm is an interactive forecast-retrieval-assimilation system based on the relaxation method of solution of the radiative transfer equation. The first guess is obtained from the six-hour forecast field generated by the General Circulation Model (GCM) of the Goddard Laboratory for Atmospheres. At present we have applied the algorithm to analyze the first two years of HIRS2/MSU data. The resulting climate data sets include: atmospheric temperature profiles, atmospheric humidity profiles, ocean surface temperature, land surface temperature, infrared cloud cover, cloud-top height and temperature, snow and ice cover, outgoing long-wave radiation, total ozone distribution, and rainfall rate index. We have conducted several tests to check the accuracy, internal consistency and stability of the results. Additional tests will be made in the future with this set as well as when multi-year data are derived. © 1991."
"7003684963;7101772062;57215451474;","Simulation of the Pinatubo aerosol cloud in general circulation model",1991,"10.1029/91GL02778","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026302659&doi=10.1029%2f91GL02778&partnerID=40&md5=205cc5f43e73307bdf553a7c0b3280f6","A high resolution stratospheric version of the NCAR Community Climate Model (CCM2) with an annual cycle was used to simulate the global transport and dispersion of the Pinatubo aerosol cloud. A passive tracer was injected into the model stratosphere over the Philippine Islands on model day June 15, and the transport was simulated for 180 days using an accurate semi‐Lagrangian advection scheme. The simulated volcanic aerosol cloud initially drifted westward and expanded in longitude and latitude. The bulk of the aerosol cloud dispersed zonally to form a continuous belt in longitude, and remained confined to the tropics (30°N–25°S) centered near the 20 mb level for the entire 180 day model run, although a small amount was transported episodically into the upper troposphere in association with convective disturbances. Aerosol transported to the troposphere was dispersed within a few weeks into the Northern Hemisphere extratropics. In the Southern Hemisphere the aerosol was mixed into the region equatorward of the core of the polar night jet during the first 50 days, but penetration into Southern Polar latitudes was delayed until the final warming in November. These results, which are generally consistent with observed behavior of the El Chichon aerosol, will be compared with observations of the Pinatubo cloud in the course of the next several months. Copyright 1991 by the American Geophysical Union."
"24322005900;","Radiation and cloud radiative properties in the European Centre for Medium Range Weather Forecasts forecasting system",1991,"10.1029/89JD01597","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026292248&doi=10.1029%2f89JD01597&partnerID=40&md5=296f0a460bf3e67a44175e51fec11415","For clear-sky conditions, the shortwave H2O absorptivity is overestimated in EC1-EC2, which leads to too large shortwave atmospheric absorption (by up to 20%) and too small downward shortwave radiation at the surface (by 5-10%. EC1 and EC2 both significantly underestimate the longwave radiative cooling, with main errors in the lower troposphere with EC1, and between 700 and 300 hPa with EC2. In cloudy conditions, EC1 shows an exaggerated sensitivity to small amounts of scatterer, a problem corrected in EC2. Due an unrealistic model cloud embedded in EC1-EC2, these schemes cannot properly represent both the shortwave planetary albedo and outgoing longwave radiation for realistic cloud liquid water contents. EC3 corrects most of these deficiencies and gives results in better agreement with those of more detailed models. -from Author"
"7003899619;7003519431;7202065258;7004991320;56269065000;55464238000;57214111808;24359688700;","Global distribution of cloud cover derived from NOAA/AVHRR operational satellite data",1991,"10.1016/0273-1177(91)90402-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026076908&doi=10.1016%2f0273-1177%2891%2990402-6&partnerID=40&md5=b84792f0d07adfb1b7e67c049cf935ad","NOAA/NESDIS is developing an algorithm for the remote sensing of global cloud cover using multi-spectral radiance measurements from the Advanced Very High Resolution Radiometer (AVHRR) on-board NOAA polar orbiting satellites. The current (Phase 1) algorithm uses a sequence of ""universal"" threshold tests to classify all 2×2 pixel arrays of GAC (4 km) observations into clear, mixed and cloudy categories. A subsequent version of the algorithm (Phase II) will analyze the previous 9-day series of mapped ( 1 2 degree) ""clear"" array data to replace the ""universal"" thresholds with space and time specific values. This will provide more accurate estimates of cloud amount for each pixel. The current algorithm is being implemented into the operational data processing stream for testing and evaluation of experimental products. Eventually, it is intended for use operationally to support weather and climate diagnosis and forecasting programs, as well as to provide clear sky radiance data sets for other remote sensing parameters, e.g., vegetation index, aerosol optical thickness, and sea surface temperature. © 1991."
"7006304268;7003969611;7004084412;","Atmospheric particles and nuclei",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040896234&partnerID=40&md5=e40fcb4720cdc56c34f3f9099a25d572","This book analyses the character of atmospheric aerosols and examines their role in the maintenance and evolution of the Earth's atmosphere. Chapters describe the origin and the physical and chemical property of aerosols; the role of aerosol particles in cloud droplet and ice formation; and the effects of particles upon climate and the radiation balance. Appendices, to illustrate the discussions, are provided for mathematical formulations and short summaries. A terminology of definitions used is presented. -N.Davey"
"6603892183;6603276395;56744278700;","Intercomparing shortwave radiation codes for climate studies",1991,"10.1029/90JD00290","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026300567&doi=10.1029%2f90JD00290&partnerID=40&md5=35aef86b11b368a5696da7eb1fb9d863","A considerable speed was detected in the response of these models to a set of well-defined atmospheric profiles. Substantial discrepancies exist among models even for the simplest case of pure water vapor absorption with standard deviation ranging from 1% to 3% for the downward fluxes at the surface and from 6% to 11% for the total atmospheric absorption. The divergences in downward surface flux increase to nearly 4% when all absorbers and the molecular scattering are considered. In cloudy conditions the divergences range from 4% to 10%, depending on the cloud optical thickness. Another major uncertainty that has been identified is the spectral averaging of the scattering properties which can result in very significant errors for low spectral resolution codes. -from Authors"
"7003625225;6505752137;7003601758;","Monthly mean upper tropospheric humidities in cloud‐free areas from meteosat observations",1991,"10.1002/joc.3370110802","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026268573&doi=10.1002%2fjoc.3370110802&partnerID=40&md5=d647b95eeabf7517477a3a737f3169dc","The purpose of this paper is to study the annual variation of the upper tropospheric relative humidity fields extracted from radiance measurements in the water vapour channel (in the thermal infra‐red at wavelengths around 6.3 μm) aboard the geostationary satellite METEOSAT. Monthly mean fields for April, July and October 1988 and January 1989 have been created from the operational Upper Tropospheric Humidity (hereafter UTH) product derived routinely at the European Space Operations Centre (ESOC). The present product retrieval is confined to cloud‐free areas in the upper troposphere, thus the monthly means represent an average over cloud‐free cases. Principally the patterns of the monthly mean UTH fields reflect the large‐scale circulation of the atmosphere. In the low latitudes, belts with relatively high and low UTH values are located over the ascending and descending branches of the ‘Hadley cell’, respectively. The distinct patterns of monthly mean UTH fields can be used to characterize the geographical structure of the Hadley cell. The UTH fields complement existing data on atmospheric humidity for use in numerical weather prediction and climatological research. The monthly mean fields presented in this paper may be useful for validating upper tropospheric water vapour fields in climate models. Copyright © 1991 John Wiley & Sons, Ltd"
"7202155374;7202257430;","Land surface hydrology in a general circulation model - global and regional fields needed for validation",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025936823&partnerID=40&md5=0602a1454dba06c00fc0aa6b7ae01d06","Treatments of land surface processes in General Circulation Models are presently limited by the realism of the simulations of precipitation and surface radiation. We examine some of the climatological fields of a 6-year model simulation, using the Community Climate Model version 1 of the National Center for Atmospheric Research with addition of a diurnal cycle and coupled to a detailed treatment of land surface processes. Comparison with satellite derived cloud forcing suggests that the model underestimates the reduction of solar radiation by clouds over Eastern United States and in high latitudes, and so probably largely explaining the excess surface radiation. We consider the annual cycle of model hydrological fields (soil moisture, runoff, precipitation, evapotranspiration, net radiation) averaged over a box covering the central part of the United States (roughly the Mississippi basin). -from Authors"
"7003314664;7102578629;","Characteristics of the tropical intraseasonal oscillation in the NCAR community climate model",1991,"10.1002/qj.49711750203","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026365238&doi=10.1002%2fqj.49711750203&partnerID=40&md5=a426d09a5d223e3b652a88fa0319b810","The structure of the intraseasonal oscillation in a perpetual January integration of the NCAR Community Climate Model (CCM) is analysed and compared with observations. The simulated oscillation is identified as an eastward‐moving perturbation in the equatorial velocity‐potential field, with predominantly zonal wave‐number‐1 structure. Analysis of its vertical and horizontal structure, based on composites, shows good agreement with the observed oscillation from station data, and from numerical weather prediction model analyses. The simulated intraseasonal oscillation is evident in the wind fields at all longitudes but its appearance in the precipitation and outgoing long‐wave radiation is confined to the eastern hemisphere. The perturbation to the zonal wind component is characterized by an out‐of‐phase behaviour between the lower and upper troposphere which is most coherent in the convective regions of the Indian Ocean and West Pacific. The stream‐function anomalies in these regions are suggestive of a coupled Rossby‐Kelvin wave, whilst in the western hemisphere the oscillation is more characteristic of a Kelvin wave. The role of cloud‐radiation interaction was studied using a parallel integration in which the cloud long‐wave forcing in the atmosphere was removed. This was found to influence the strength of the oscillation but had no significant impact on the period. In common with other model simulations of the intraseasonal oscillation, the period was found to be too short, near 25 days. Reasons for this are discussed in the context of a similar analysis of a perpetual July integration in which a much slower (period near 54 days) and less coherent oscillation was identified. Copyright © 1991 Royal Meteorological Society"
"7406582182;","Human occupance and the physical environment",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026046656&partnerID=40&md5=4b20dbf70948f15d44aa92e5fa679a5b","Considers the processes of anthropogenic environmental change, with human occupancy of the UK resulting in alterations to the physical and biological environments which have increased in pace and severity as the population grew, organisation improved, and technology evolved. The chapter first considers the significance of natural hazards, particularly river and coastal flooding, to UK society and the measures taken to minimise their impact. The author then discusses human impacts on climate (local climate change, urban heat islands, airflow, visibility, cloud cover and precipitation, and recent changes), morphological changes (especially those due to mineral extraction), and the processes of land dereliction and reclamation. The conclusion stresses the increasing complexity of the two-way interaction between human occupancy and the physical environment over the last half century, and suggests that this tendency will increase further in the future. -P.Hardiman"
"7102783229;","Middle Atmosphere Aerosols and Their Effects",1991,"10.5636/jgg.43.Supplement2_667","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026379656&doi=10.5636%2fjgg.43.Supplement2_667&partnerID=40&md5=229a2f8356bd44abf32fb424ada4798f","The middle atmosphere holds a rich variety of particulate matter, ranging from meteoritic debris to sulfate aerosols to polar stratospheric ice clouds. Volcanic eruptions strongly perturb the stratospheric sulfate (JUNGE) layer. High-altitude “noctilucent” ice clouds condense at the cold mesopause. The properties of these particles-including composition, size and geographical distribution-are discussed, and their global effects-including chemical, radiative and climatic roles-are surveyed. Polar stratospheric clouds (PSCs) catalyze reactions of chlorine compounds that “activate” otherwise inert chlorine reservoirs, leading to severe ozone depletions in the southern polar stratosphere during austral spring. PSCs also modify the composition of the polar stratosphere through complex physicochemical processes, including dehydration and denitrification. The sulfate aerosol layer can reflect solar radiation and increase the planetary albedo, thereby cooling the surface and altering the climate. Major volcanic eruptions, which enhance the stratospheric sulfate aerosol burden by a factor of 100 or more, may cause significant global climatic anomalies. Sulfate aerosols also appear capable of activating stratospheric chlorine reservoirs on a global scale. Accordingly, if atmospheric concentrations of chlorine (associated with anthropogenic use of chlorocarbons) increase by a factor of two or more in future decades, significant worldwide ozone depletions could occur. © 1991, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved."
"7006307463;7005635934;7004920873;7003833060;7401491382;","Perturbation of the northern hemisphere radiative balance by backscattering from anthropogenic sulfate aerosols",1991,"10.1034/j.1600-0889.1991.t01-1-00013.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982721244&doi=10.1034%2fj.1600-0889.1991.t01-1-00013.x&partnerID=40&md5=7205bafdec0d235e700dd7990e5b5a9a","Anthropogenic sulfate (SO4=) aerosol particles play two potential roles in the radiative climate of the earth. In cloud‐free air, SO4= particles scatter sunlight, some of which is lost to space, thereby reducing solar irradiance at the ground. The same particles can act as cloud condensation nuclei (CCN), the number concentration of which is an important determinant of cloud albedo. This albedo effect, in turn, also influences incoming short‐wave solar radiation. Development of a three‐dimensional global model for estimating the SO4= aerosol mass concentration, along with previously‐acquired information on the scattering and back‐scattering coefficients per unit mass concentration allow calculation of the effects of anthropogenic SO4= aerosol on clear‐sky optical depth. Subsequently, this can be used to estimate the change in hemispheric and global average reflected solar radiation. The conclusion is that the change of reflected solar flux due to anthropogenic SO4= averaged over the Northern Hemisphere is ca. − 1.1 Wm−2, which is comparable but opposite in sign to the present‐day radiative forcing by anthropogenic CO2, + 1.5 Wm−2. Because of the spatial variability of the anthropogenic SO4= distribution, its meteorological effects must be studied regionally. That is, global models with regional resolution and regional data are required. Unlike the direct effect on solar irradiance, the relationship of CCN number concentration to mass concentration is not known. Thus it is not yet possible to make quantitatively reliable statements about anthropogenic forcing of cloud albedo, although there is qualitative evidence that the CCN effect may also be substantial. Copyright © 1991, Wiley Blackwell. All rights reserved"
"7006307463;7005635934;7004920873;7003833060;7401491382;","Perturbation of the northern hemisphere radiative balance by backscattering from anthropogenic sulfate aerosols*",1991,"10.1034/j.1600-0870.1991.00013.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981657845&doi=10.1034%2fj.1600-0870.1991.00013.x&partnerID=40&md5=1dab124614e273f02ecce23dd048eb65","Anthropogenic sulfate (SO4=) aerosol particles play two potential roles in the radiative climate of the earth. In cloud‐free air, SO4= particles scatter sunlight, some of which is lost to space, thereby reducing solar irradiance at the ground. The same particles can act as cloud condensation nuclei (CCN), the number concentration of which is an important determinant of cloud albedo. This albedo effect, in turn, also influences incoming short‐wave solar radiation. Development of a three‐dimensional global model for estimating the SO4= aerosol mass concentration, along with previously‐acquired information on the scattering and back‐scattering coefficients per unit mass concentration allow calculation of the effects of anthropogenic SO4= aerosol on clear‐sky optical depth. Subsequently, this can be used to estimate the change in hemispheric and global average reflected solar radiation. The conclusion is that the change of reflected solar flux due to anthropogenic SO4= averaged over the Northern Hemisphere is ca. − 1.1 Wm−2, which is comparable but opposite in sign to the present‐day radiative forcing by anthropogenic CO2, + 1.5 Wm−2. Because of the spatial variability of the anthropogenic SO4= distribution, its meteorological effects must be studied regionally. That is, global models with regional resolution and regional data are required. Unlike the direct effect on solar irradiance, the relationship of CCN number concentration to mass concentration is not known. Thus it is not yet possible to make quantitatively reliable statements about anthropogenic forcing of cloud albedo, although there is qualitative evidence that the CCN effect may also be substantial. Copyright © 1991, Wiley Blackwell. All rights reserved"
"57198050391;25930906600;","Theory and development of a one dimensional time dependent radiative convective climate model",1991,"10.1016/0045-6535(91)90326-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025817598&doi=10.1016%2f0045-6535%2891%2990326-9&partnerID=40&md5=000bbce45a427ae5f6c34fae492afaa9","A time dependent one dimensional radiative convective model (1D RCM) is developed to study the changes in the Earth's temperature that may be caused by increasing levels of CO2 and other trace gases. Special emphasis is given to the theory and development of the model so that it may be easily used by others. The sensitivity of the Earth's surface temperature to variations in the solar constant, surface albedo, and cloud cover fraction and height is included. The model is found to predict an approximate change in surface temperature of 1.9 K for a doubling of atmospheric CO2 (from 320 to 640 ppm). This compares favorably with other previously published results for similar models. The influence on mean global temperature of variations in the atmospheric concentrations of CO2, CH4, N2O, CCl3F, CCl2F2, and volcanic aerosols over the past century is simulated with the model. We find that this simulated temperature record compares well with the record of mean global temperature reconstructed from observations. © 1991."
"35414069200;7003518357;","The validation of microwave spaceborne observations by surface-based remote sensors",1991,"10.1016/0921-8181(91)90101-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949275525&doi=10.1016%2f0921-8181%2891%2990101-2&partnerID=40&md5=8a745d6a20b23087c574c6a3428986ac","Passive microwave observations from polar-orbiting satellites provide meteorologically important information on temperature profile, water vapor, and cloud liquid water, The variable measured by radiometers in radiance, or brightness temperatures, as a function of frequency, viewing angle, and polarization. Meteorological parameters are then extracted from the radiance measurements by retrieval algorithms. The utility of these parameters, both in operational meteorology and in monitoring climate change, depends on the calibration and stability of the instrument, and on the type of retrieval algorithm that is used. Utimately, the derived parameters must be compared with ground truth. For temperature and water vapor soundings, radiosondes are frequently used for validation and calibration. However, for the climatologically important variable cloud liquid water, conventional measurements are not adequate, and surface- and aircraft-based remote sensor measurements are required. In this paper, calibration of microwave instruments is discussed and comparisons with various sources of ground truth are presented. In addition, a possible role for surface-based remote sounders in the calibration and validation of satellite products is suggested. These remote sounders include microwave radiometers, wind profilers, and Radio Acoustic Sounding Systems (RASS). © 1991."
"7003886966;35476924900;7102284673;7401663065;7003302886;7004628271;","Distributed parameter models to analyze the impact of human disturbance of the surface hydrology of a large tropical drainage basin in southern Africa",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026313327&partnerID=40&md5=01acbcb8b7811604c9d7a45cbde229a2","A macro-scale model of the Zambezi River has been developed and organized as a set of interaction algorithms and geographical-references data planes. The drainage basin is represented by 409 single grid cells 0.5 degree (lat. × long.), forming a topologic network with a basin area of 1.22 million km2. A water balance model converts spatially and temporally-varying climate fields for mean monthly precipitation, temperature, cloud cover and global irradiance into predictions of soil moisture, evapotranspiration and runoff. Runoff is routed through a fluvial transport algorithm which links the catchment's grid cells as a set of simultaneous equations to predict channel discharge and wetland inundation. Model predictions are checked against observed station data to produce a calibrated model of the pre-disturbed state. From this benchmarked condition, the impacts of altered surface hydrology can be explored using the model. -from Authors"
"57207518890;7006506458;","Non-linear variability in geophysics: scaling and fractals",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040889149&partnerID=40&md5=6c23097b2d2b46136aebf28ca397ec22","Contains 24 papers from a wide variety of geophysical specialisations, though all are concerned with a basic aspect of geophysical phenomena: highly variable fractal structures. This extreme spatial variability, routinely encountered by geophysicists, can now be easily dealt with by data analysis and modelling. This essentially research-based book is structured into 5 sections: turbulence of geophysical fluid dynamics (5 papers); data analysis techniques (4 papers); modelling of analysis of clouds, rain, and other atmospheric fields (5 papers); modelling and analysis of the climate, oceans and in solid earth geophysics (7 papers); and remote sensing (3 papers). Most papers are abstracted separately. -R.C.Medler"
"6602353991;","Glaciers of the Middle East and Africa - glaciers of Iran",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026304817&partnerID=40&md5=10b5a11736876c5e499a31736132f994","During the Pleistocene, glaciation was much more extensive in Iran and included the present-day centers of glaciation and three other mountain areas. During that time the climatic snowline was 600 to 1100 meters lower than the present level. The temperature structure was thought to be similar except that the mean temperature was 4 to 5°C lower and the precipitation/evaporation ratio was higher. Cloud-free Landsat data exist for all the glacier areas of Iran. However, Landsat data are of limited usefulness for glacier studies and monitoring in Iran because of the resolution of the spacecraft sensors, the size of the glaciers, and the prevalent snow and debris cover. -from Author"
"57196396429;","Water balance and general circulation parameters deduced from operational satellites: The example of tropical Africa",1991,"10.1016/0273-1177(91)90408-C","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025953563&doi=10.1016%2f0273-1177%2891%2990408-C&partnerID=40&md5=ef3a142e710180424cc332ff5efab418","The capabilities and deficiencies of the present system of operational satellites for retrieving energy and water balance parameters in the tropics are stressed on the basis of specific studies about the African climate performed in LMD : these studies concern the atmospheric phase of the cycle, and specifically convective systems, precipitations, winds and general circulation. It is shown that some improvements can still be made in the processing of existing data, but that more quantitative studies of such important processes as relationships between precipitations, latent heat release and tropical circulations, or cloud-radiation interactions, would require more dedicated space missions, with appropriate instrument groupings. © 1991."
"7005409255;","Operational estimation of precipitation from satellite data",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026304357&partnerID=40&md5=84cec0bbc4adc1df2ad90668a41c37b7","The National Environmental Satellite, Data, and Information Service (NESDIS) is providing the following products for monitoring and assessing global precipitation: 1) Infrared (IR) Histograms of the GOES Precipitation Index between 40°N and 40°S; 2) Global Cloud Liquid Water from the Special Sensor Microwave/Temperature (SSM/T) - over water only; 3) Global Precipitation from the Special Sensor Microwave/Imager (SSM/I) - over land and water. These products are being collected and verified by NOAA's Climate Analysis Center (CAC). Over the next 3-5 years, product improvements are planned through: 1) integration of the microwave, visible, and IR measurements to produce a tri-spectral precipitation product; and 2) modification of the tri-spectral global precipitation product for seasonal variations, regional differences, and collateral data. -from Author"
"7003627420;7102791210;7006558320;6602314510;7006380320;24361554000;6701561563;7004004501;57215768509;57197476904;6507499476;8432789600;24350468500;","West Cameroon Quaternary lacustrine deposits: preliminary results",1991,"10.1016/0899-5362(91)90065-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026300894&doi=10.1016%2f0899-5362%2891%2990065-7&partnerID=40&md5=2fd821ecc9db9b08fc5a362a6f94f496","We present preliminary results from the study of a 23.50 m core (BM-6) representing the last 25 000 years. The core was collected in Barombi Mbo, an explosion crater lake formed probably during the Quaternary. The finely laminated sediment are composed mostly of dark brown to green clay rich organic matter (5-10% organic carbon). Each couplet is commonly composed of a lower unit rich in quartz, plant debris, muscovite and sponge spicules, and of a more clayey upper unit often with siderite (FeCO3) crystals. The average periodicity for one couplet is between 6 and 20 radiocarbon years. The pollen results, which are compared with those of another forested site in Ghana, demonstrate the presence of a forest refuge in West Cameroon during the last major arid period, about 18 000 years BP. At the same time that equatorial forest was broken up, elements of montain vegetation descended to the lowlands. To provide an explanation for these phenomena marked by a drying and cooling of the climate, modern examples of extensions of montain biotopes to low altitude are described. These localized extensions are due to the persistence of cloud cover, often of stratiform type, generated over the relatively cold water of ocean upwellings. Such lowering of sea-surface temperature might be the primary regional cause of the changes of climate and vegetation that occurred in humid tropical Africa. The upwelling, presently synchronous throughout the Guinea Gulf, amplify the trade winds, which could account for the observed changes inland. © 1991."
"7003937421;","Operational production of multichannel sea surface temperatures from NOAA polar satellite AVHRR data",1991,"10.1016/0921-8181(91)90088-E","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949275940&doi=10.1016%2f0921-8181%2891%2990088-E&partnerID=40&md5=f6ef3c68b2bdf3a193da8d6643ddeb59","Data from the Advanced Very High Resolution Radiometer (AVHRR) flown on the NOAA series of polar-orbiting environmental satellites have been used to produce operational sea surface temperature (SST) products since January 1979. With the implementation of linear Multichannel SST (MCSST) equations and multichannel cloud screening tests in November 1981, accuracy and resolution improved significantly. Recently (March 1990), accuracy has been improved again with the implementation of nonlinear SST equations. When compared with drifting buoy SST observations, daytime and nighttime satellite SST observations produced from these new equations have global biases less than 0.3°C and standard deviations less than 0.7°C. From a daily global set of approximately 120,000 SST observations at 8 km resolution, series of operational products are produced routinely, some of which are of interest to the climate community. © 1991."
"6603285253;","Indirect calibration of visible channel data",1991,"10.1016/0921-8181(91)90105-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949276064&doi=10.1016%2f0921-8181%2891%2990105-6&partnerID=40&md5=23921b6b3d68a65b68828a85a961ed9c","To provide quantitative measurements for Earth studies accurate and comprehensive calibration of satellite radiometers is critically needed. The recent increase in the use of satellite data for climate studies calls for the retrieval of physical parameters from the measured radiances and therefore for absolute calibrations that are known over long time periods. However, even the use of classification or ""index"" type analyses of satellite data to monitor changes in climate requires that the relative stability of the satellite radiometers be known for long-term data sets. Moreover, plans to collect global satellite data over decadal periods, to monitor changes in surface conditions and in climate, require a calibration standard that can be transferred from one satellite to another in a series. Although most instruments undergo a thorough calibration prior to their launch on a satellite, there appears to be no predictable relationship between these pre-launch calibrations and the post-launch performance. Thus, comprehensive, well-documented post-launch calibrations are needed. Because the solar channels used for imaging on most operational satellites do not have onboard calibration capabilities, a number of indirect approaches have been developed using the Earths surface as a target. A variety of earth targets have been used in calibration ranging from a single target (such as White Sands, NM) to multiple targets covering the entire globe. The use of such targets to monitor the relative calibration of satellite instruments over long time periods introduces a number of uncertainties such as diurnal and seasonal changes in the radiation from the target as seen by the satellite. These temporal changes arise from variations in viewing and illumination geometry, changes in the atmosphere, navigation errors, changes in the surface characteristics (such as soil moisture and vegetation), and cloud variations. Relative calibration methods require periodic absolute calibration checks. There is a demonstrated need for routine aircraft calibration flights to validate the various approaches. © 1991."
"7005409255;","Operational estimation of precipitation from satellite data",1991,"10.1016/0921-8181(91)90075-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949276742&doi=10.1016%2f0921-8181%2891%2990075-8&partnerID=40&md5=80a8efbf871ea177d9bd10633ee28c9f","Since 1978, the National Environmental Satellite, Data, and Information Service (NESDIS) of the National Oceanic and Atmospheric Administration (NOAA) has been operationally producing estimates and outlooks of heavy precipitation to the National Weather Service (NWS) Forecast Offices and River Forecast Centers (RFC). These estimates and outlooks aid the NWS in issuing flash flood watches and warning. Additionally, NESDIS is providing the following products for monitoring and assessing global precipitation: (1) Infrared (IR) Histograms of the GOES Precipitation Index between 40°N and 40°S; (2) Global Cloud Liquid Water from the Special Sensor Microwave/Temperature (SSM/T)-over water only; (3) Global Precipitation from the Special Sensor Microwave/Imager (SSM/I)-over land and water. These products are being collected and verified by NOAA's Climate Analysis Center (CAC). Over the nest 3-5 years, product improvements are planned through: (1) integration of the microwave, visible, and IR measurements to produce a tri-spectral precipitation product; and (2) modification of the tri-spectral global precipitation product for seasonal variations, regional differences, and collateral data. © 1991."
"57215742555;","Earth's surface temperatures and the global water cycle [Températures de la surface de la terre et le cycle global de l’eau]",1991,"10.1080/02626669109492532","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026273035&doi=10.1080%2f02626669109492532&partnerID=40&md5=ab8ce886d8c1434f2e54d6ab858129db","At a global scale the troposphere is a closed water vapour reservoir with interlinked cycles of heat and water. The global (macroscale) water vapour dynamics are analysed in three stages: (a) a semi-empirical simulation procedure quantifying the internal relationships among the vapour pressure gradients at the Earth's surface, within the overheated and unsaturated nearsurface layer, and the precipitation formation zone; (b) an analytical description of the effect of changing the Earth's surface temperature on the vapour pressure gradient at cloud base, giving insight into the feedback mechanism between the Earth's surface evaporation and precipitation formation; and (c) a combination of the previous two stages leading to the equilibrium criteria for vertical vapour flux. Needs and opportunities for applications combined with other approaches in climate research are outlined. Fuller details are given elsewhere (Szesztay, 1991). © 1991 Taylor and Francis Group, LLC."
"7004236861;6603768180;7003633107;","Tree‐ring reconstructed sunshine duration over central USA",1991,"10.1002/joc.3370110305","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026267649&doi=10.1002%2fjoc.3370110305&partnerID=40&md5=1ff386d7b74a1a7ec732ccc9ab68bbcc","Tree‐ring chronologies of baldcypress (Taxodium distichum) and post oak (Quercus stellata) from the central United States of America are directly correlated with precipitation, and inversely with percentage possible sunshine during the growing season (March‐June). Partial correlation analysis indicates that precipitation is the most important climate signal in the growth of these trees, but sunshine duration accounts for an additional 22 per cent of the radial growth variance independently of the growth influences of precipitation or temperature. Because the internal moisture balance of trees and ultimately the width of annual tree‐rings assimilate the direct and interactive effects of sunshine duration, temperature, and especially precipitation, the tree‐ring chronology can explain 60 per cent of the variance in regional sunshine duration. Consequently, the derived reconstruction retains more sunshine duration information than is reflected by the simple covariance between rainfall, cloud cover, and sunshine. A tree‐ring reconstruction of sunshine duration from AD 1700 to AD 1980 suggests that short‐period changes in the mean, variance, and persistence of cloud cover have occurred over the past 281 years. Analysis of the reconstruction indicates that strong El Niño events are often associated with cloudy growing season conditions over the central USA. The full 281‐year reconstruction and the 85‐year instrumental sunshine data also contain prominent 5‐ to 10‐year sunshine oscillations, which frequently help to induce trends lasting up to 20 years. The sunshine reconstruction does not, however, reveal any statistically significant 30‐year‐long linear trends in sunshine duration since 1700. Copyright © 1991 John Wiley & Sons, Ltd"
"7003806125;57199235114;","French space programmes related to global change",1991,"10.1016/0273-1177(91)90423-H","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026051021&doi=10.1016%2f0273-1177%2891%2990423-H&partnerID=40&md5=60d2c3d435563b805e6e95a680ac42f8","The guidelines of the national and cooperative environmental programmes conducted by CNES are complementarity with third agencies' programmes, synergism between scientific and application projects, and promotion of innovative concepts likely to meet the requirements of the World Climate Research and International Geosphere-Biosphere Programmes. While the on-going SPOT series is to provide imagery of land surfaces until 2000, the TOPEX/POSEIDON altimetric mission is being developed by NASA and CNES for launch in mid-1992 in phase with the WOCE intensive field experiments. The design study of the AVISO ocean data system, and the development on behalf of ESA of the ERS-1-dedicated CERSAT facility are consolidating the French effort in space oceanography. Two other research space missions are studied by CNES and French laboratories. BEST, whose phase A study is nearing completion, is a low-altitude, low-inclination, GEWEX-dedicated mission for the investigation of the water and energy cycle in the tropics, with a target launch date in the late 1990's. The phase A study of GLOBSAT, a more IGBP-oriented mission concept, has just been initiated. The first objective of this mission in polar orbit considered for launch around 1997, is to collect comprehensive data sets needed to document key processes related to cloud/radiation interaction, stratospheric/tropospheric chemistry and dynamics of continental and marine ecosystems. The second objective is to start monitoring long-term trends of parameters required to close global budgets of carbon and ozone. The analysis of this space mission concept is conducted in parallel with the development of instruments of opportunity to be flown onboard foreign satellites, and of airborne sensors, either precursor to space instruments or designed for process studies and validation of space data. © 1991."
"6701799761;16419940400;57206416522;","Do we know what difference a delay makes?",1991,"10.1029/90EO00413","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984508961&doi=10.1029%2f90EO00413&partnerID=40&md5=2e0e6c92848b79102e2a336e7d7a85ec","In our original comment [Risbey et al.., 1991] we argued that the work of Schlesinger and Jiang [1991a] is too limited to determine whether or not (as they put it) “the penalty is small for a 10‐year delay in initiating the transition to a regime in which greenhouse‐gas emissions are reduced.” In their reply, Schlesinger and Jiang [1991b] (hereafter S&J) presented their reasons for concluding definitively that the penalty is small. However S&J's discussion of the evidence and literature on climate change and greenhouse warming contains significant omissions and mis‐statements. In dismissing our concern that their model was too simple to evaluate the possibility of abrupt climate change, S&J rely on results from coupled ocean‐atmosphere general circulation models (GCMs), in particular the work of Cubasch et al.. [1991]. Here S&J make two claims, one of which is incorrect and the other questionable. First, they claim that “the coupled atmosphere‐ocean model of Cubasch et al. [1991] does allow the nonlinearities that Risbey et al.. [1991] criticize our simple model for not including.” In fact we explicitly mentioned changes in polar ice caps [Oerlemans and van der Veen, 1984] and release of methane from clathrates [MacDonald, 1990; Bell, 1982], neither of which are included in the model of Cubasch et al.. [1991]. Indeed, none of the published simulations of global warming using coupled ocean‐atmosphere GCMs include these effects. Nor do these models yet include in their enhanced greenhouse simulations many of the possible feedbacks involving the carbon cycle and biosphere [Lashof, 1989; Bacastow and Maier‐Reimer, 1990; Sellers, 1987] that could significantly alter greenhouse gas concentrations and surface properties. The published simulations with these models do allow for some changes in deep ocean circulation and cloud behavior, but there is controversy over whether they correctly represent these processes [Marotzke, 1991; Mitchell, 1989; Cess, 1990]. In addition the coupled models must be arbitrarily tuned (requiring substantial artificial fluxes of heat and moisture) to get the current climate right [Manabe et al.., 1991; Cubasch et al.., 1991]. Their greenhouse change simulations are at least partly constrained by these flux adjustments. ©1991. American Geophysical Union. All Rights Reserved."
"8225183400;7004189939;6506122255;6603504858;7004928556;7006113978;7006005654;57199741814;","Global warming: Evidence for asymmetric diurnal temperature change",1991,"10.1029/91GL02900","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026283891&doi=10.1029%2f91GL02900&partnerID=40&md5=573fc98be026746e0ad2f2eca9d0fca6","Analyses of the year‐month mean maximum and minimum surface thermometric record have now been updated and expanded to cover three large countries in the Northern Hemisphere (the contiguous United States, the Soviet Union, and the People's Republic of China). They indicate that most of the warming which has occurred in these regions over the past four decades can be attributed to an increase of mean minimum (mostly nighttime) temperatures. Mean maximum (mostly daytime) temperatures display little or no warming. In the USA and the USSR (no access to data in China) similar characteristics are also reflected in the changes of extreme seasonal temperatures, e.g., increase of extreme minimum temperatures and little or no change in extreme maximum temperatures. The continuation of increasing minimum temperatures and little overall change of the maximum leads to a decrease of the mean (and extreme) temperature range, an important measure of climate variability. The cause(s) of the asymmetric diurnal changes are uncertain, but there is some evidence to suggest that changes in cloud cover plays a direct role (where increases in cloudiness result in reduced maximum and higher minimum temperatures). Regardless of the exact cause(s), these results imply that either: (1) climate model projections considering the expected change in the diurnal temperature range with increased levels of the greenhouse gases are underestimating (overestimating) the rise of the daily minimum (maximum) relative to the maximum (minimum), or (2) the observed warming in a considerable portion of the Northern Hemisphere landmass is significantly affected by factors unrelated to an enhanced anthropogenically‐induced greenhouse effect. Copyright 1991 by the American Geophysical Union."
"6603162518;7005316058;","Nocturnal air and road surface temperature variations in complex terrain",1991,"10.1002/joc.3370110408","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84985216669&doi=10.1002%2fjoc.3370110408&partnerID=40&md5=fc06c863ac6080207d5208a0e1980c4d","This paper is part of an ongoing project dealing with the modelling of local climate for predicting temperature variations and risks of road slipperiness under various synoptic conditions. Temperature recordings from mobile measurements taken along road stretches have been analysed to determine the influence of valleys on the variation in air and road surface temperatures. During clear, calm nights, the variation in air temperature between valley bottoms and surrounding areas can be related to geometric properties of valleys, such as depth and width. It is seen that temperature differences between valleys and surrounding areas increase with increasing depth and width. The prevailing wind speed has been found to be a major factor controlling the variation in temperature. The variation in air temperature is totally smoothed out in situations in which there is an ambient wind speed exceeding 3 m s−1. In the interval 2–3 m s−1, the degree of wind exposure in valleys is of importance for the magnitude of the air temperature differences. Counter‐radiation from clouds has been found to significantly reduce the intensity of cold air pools. Under partly cloudy situations (3–5 octas) with no wind, the temperature difference between valley bottoms and surrounding areas differs by approximately 6°C in comparison with clear, calm situations. The relationship between differences in air and road surface temperature has also been studied. In general, an increase in cold air pool intensity of 1°C lowers the road surface temperature by 0·4°C. Copyright © 1991 John Wiley &amp; Sons, Ltd"
"7401636555;7005123759;6701369507;7004247708;57214416067;7003341337;7006171180;7701314150;8772820800;","Satellite remote sensing of surface energy and mass balance: Results from FIFE",1991,"10.1016/0034-4257(91)90011-T","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026271254&doi=10.1016%2f0034-4257%2891%2990011-T&partnerID=40&md5=e51852c7a5e0430cb380dd1aa0313859","In FIFE a diverse, interdisciplinary group of scientists are cooperating to understand how the earth's land-surface vegetation and atmospheric boundary layer interact to affect weather and climate. The focus of this research is the interception of solar and long-wave radiation by a vegetated surface, and the subsequent thermodynamic and biological control of sensible and latent heat release. In addition, the science teams are investigating the use of satellite remote sensing to monitor the components of the surface energy balance at point, regional and global scales. Field experiments were conducted in the summer of 1987 and again in the summer of 1989. Analyses of the 1987 data are reasonably mature, whereas the 1989 data analyses are in the early stages. In this paper we summarize the results of the analyses to date. The analyses have shown that the hypotheses linking energy balance components to surface biology and remote sensing are reasonable at a point level, and that satellite remote sensing can potentially provide useful estimates of the surface energy budget. GOES data have been used to estimate solar insolation at the earth's surface to an accuracy of about 21.6 W m-2 and about 8.2 W m-2 for photosynthetically active radiation. The ratio of near-infrared to red reflectance has also shown to be linearly related to measured CO2 flux. Radiometric temperatures estimated from remote sensing are highly correlated to the canopy aerodynamic temperatures; however, the remote sensing estimation of H to useful accuracies (± 100 W m-2) appears to be a more difficult problem than the accurate estimation of LE. The investigation of atmospheric scattering and absorption effects on satellite remote sensing of surface radiance shows that the magnitude of atmospheric opacity variations within the FIFE site and with season can have a large effect on satellite measured values of surface radiances. However, comparisons of atmospherically corrected TM radiances with surface measured radiances agreed to within about 2% in the visible and near-infrared wavelengths and to 6% in the mid-infrared. Looking at the frequency of cloud-free (&lt;10%) acquisitions actually achieved during FIFE shows that for land-surface climatology, multiple polar orbiters may be required to achieve the minimum desired acquisition frequency: once each 5 days. © 1991."
"6603423481;","De-hazing Landsat Thematic Mapper images",1991,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026358816&partnerID=40&md5=1953388c225a18f7fada506cdd886621","An algorithm using no external parameters is proposed for removing the effect of aerosols from Landsat TM images. It uses the haze or fourth tasseled cap parameters as a measure of aerosol density for each pixel and computes corrected TM values according to that parameter. Particulates present in the atmosphere (aerosols) constitute a major problem in remote sensing, not only because they mask the objects being imaged but also because they alter their spectral signature. They are common at all latitudes, but smoke from bush fires and a persistent atmospheric veil during the dry season are occasional but major problems encountered in tropical countries. The methodology and the applications presented are therefore derived for the latter environment. The atmosphere affects the detected radiance of objects at ground level either on a global basis, i.e., by affecting all ground pixels (IFOVs) in a similar way, or on a local basis, i.e., when the effect varies from one ground pixel to another. The global effects find their origin in small-scale variations in the nature of the atmosphere in the area of interest. Correction of such effects on digital imagery can be performed through external or internal procedures. The former methods use known or inferred atmospheric parameters (precipitable water, horizontal visibility, season, climate, etc.) subsequently computed through a suitable algorithm in turn applied to an adequate atmospheric model, together with calibration data of the signal recorded by the satellite and conditions of illumination at the time of image acquisition. The latter methods rely on information provided by the image itself and are based on the fact that data recorded in the near infra-red are differently affected by atmospheric effects than those recorded in the visible range. The method described hereafter is based on internal procedures. It is intended to provide a correction of local effects, whenever due to haze, smoke plumes, clouds, or other aerosol particles locally present between the ground pixel and the sensor and whose spectral signature alters that of the pixels at the ground. We will refer to those aerosols as haze. Two parameters must be computed for the removal of their effects: first, the amount of haze present, and second, the relationship between the former and the actual DN values recorded in the different bands. -from Author"
"7408612236;57206400330;","Surface forcing of interannual variations in the radiation balance over North Africa part I: Partitioning the surface and cloud forcing",1990,"10.1007/BF00138367","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249962043&doi=10.1007%2fBF00138367&partnerID=40&md5=2c3e7573f1435fd761578eb92ee00711","Previous research has shown that most significant interannual variability of the net radiation balance is confined to a few distinct centers at low latitudes. North Africa is the only continental region within this zone which undergoes large amplitude interannual changes. This two part study focuses on the origins of the North African radiation balance variability, its relationship to precipitation processes, and the potential impact of confined regional variations on global climate. Part I investigates how net radiation perturbations can be decomposed into surface induced components and cloud induced components. The methodology is based on lengthy time series of satellite derived radiation budget and cloudiness quantities in conjunction with a technique derived from the Cess et al. (1982) study involving the formulation of a climate sensitivity parameter. The analysis shows that a significant portion of the interannual modulation of net radiation over North Africa arises from surface influences. Furthermore it appears that a significant part of the mechanism inducing these changes takes place through precipitation controls on the land surface. Cloud induced anomalies are important but represent the weaker of the two processes. Since North Africa is the sink portion of a large scale, cross-meridional energy transport dipole counterpoised to a large scale energy source in the Western Pacific, it is of fundamental importance on the global scale to determine the origins of net radiation variations within the sink. The analysis indicates three dominant time scales associated with precipitation feedback on the net radiation anomalies; a slow manifold of approximately 20 months; a fast manifold of 2.5 months; and a semi-annual manifold. These time scales underlie the surface and cloud forced net radiation anomalies in which southern, central, and northern latitude sectors of North Africa exhibit their own distinct modes of control on the regional radiation balance. © 1990 Kluwer Academic Publishers."
"7102106414;7403494242;","Examination of Morton's CRAE model for estimating daily evaporation from field-sized areas",1990,"10.1016/0022-1694(90)90156-R","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025573374&doi=10.1016%2f0022-1694%2890%2990156-R&partnerID=40&md5=06bcba28518775417a27828969fde958","Morton's complementary relationship areal evapotranspiration (CRAE) model was originally designed to provide regional estimates of monthly evapotranspiration. Often, however, hydrologists and others require estimates of evapotranspiration for field-sized land units under a specific land use, for shorter intervals of time. This paper examines CRAE with respect to the algorithms used to describe different terms and its applicability to reduced spatial and temporal scales. Daily estimates by CRAE of atmospheric radiation fluxes during the summer months are compared with monitored values. It is shown that errors in estimation of the extra-terrestrial flux, the transmittancy of clouds to short-wave radiation, the surface albedo and the net long-wave flux result in standard deviations of the difference between 'modelled' and 'measured' net all-wave radiation for 1-, 5- and 10-day periods of 2.58, 1.8 and 1.50 MJm-2 day-1 respectively. The assumption in CRAE that the vapour transfer coefficient is independent of wind speed may lead to appreciable error in computing evapotranspiration. A procedure for incorporating a wind correction factor is described and the improvement in estimating regional evaporation is illustrated. Comparisons of evapotranspiration estimates by CRAE and measurements obtained from soil moisture and precipitation observations in the semi-arid, cold-climate Prairie region of western Canada demonstrate that the assumptions that the soil heat flux and storage terms are negligible, lead to large overestimation by the model during periods of soil thaw. © 1990."
"7202754530;6701840054;7003332823;","A sensitivity experiment for the removal of Arctic sea ice with the French spectral general circulation model",1990,"10.1007/BF00195850","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001967206&doi=10.1007%2fBF00195850&partnerID=40&md5=e26f0ee0fa2f1eb9b81e9015c143236c","Sea ice has a major influence on climate in high latitudes. In this paper we analyzed the impact of removal of Arctic sea-ice cover on the climate simulated by a T42 20-level version of the French spectral model ""Emeraude"". The control experiment was the second winter of an annual cycle simulation of the present climate. In the perturbed simulation the Arctic sea-ice cover was replaced by open ocean maintained at the freezing temperature of sea water. The zonal mean patterns of the model response were found to be in good agreement with earlier simulations of Fletcher et al. and Warshaw and Rapp. The atmospheric warming, caused by the increase of upward fluxes of sensible and latent heat and of longwave radiation from the ice-free ocean surface, is largely limited to the high latitudes poleward of 70° N and the lower half of the troposphere and leads to a surface pressure decrease and a precipitation increase over this area. We also analyze the geographical distribution of the response and the mechanisms that can explain the simulated cooling over Eurasia in relation to the energy budget at the surface. Finally, we discuss the reduction of cloud cover over the ice-free Arctic, which was an unexpected result of our simulation, and conclude that further studies are necessary to resolve the question of cumulus convection and cloud process parameterization in high latitudes. © 1990 Springer-Verlag."
"7006518289;","Development of global coupled ocean-atmosphere general circulation models",1990,"10.1007/BF00195851","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345080677&doi=10.1007%2fBF00195851&partnerID=40&md5=2bee16ccbfb55154dd29df3abbc7cea5","It has long been believed that a climate model capable of realistically simulating many features of global climate, variability, and climate change must interactively represent the major components of the dynamically coupled climate system, particularly the atmosphere, ocean, and cryosphere. This effort traditionally has been constrained by computing power, our understanding of the observed system, and climate modeling capability. With the advent of supercomputers, improved understanding of global climate processes, and computationally efficient general circulation climate models, we have witnessed a rapid increase in the simulation of global climate by coupling together various representations of atmosphere, ocean, and sea ice. Beginning in the late 1960s and continuing through the early 1980s, general circulation models (GCMs) of the atmosphere, ocean, and sea ice were coupled and run asynchronously to produce credible simulations of the global climate. Systematic errors in these component models later led some modeling groups to use flux correction or flux adjustment, whereby either one or several of the variables at the air-sea interface are adjusted to bring the simulations in closer agreement with observations. Further advances in computing power and climate modeling techniques in the past few years have allowed global coupled ocean-atmosphere GCMs to be run synchronously (i.e., atmosphere and ocean communicate at least once each model day). Computing constraints, combined with the need for multidecadal climate integrations, still only allow relatively coarse-grid ocean GCMs to be coupled to correspondingly coarse-grid atmospheric models (on the order of 500 km × 500 km). However, results from this current generation of global, coupled GCMs have revealed interesting characteristics associated with ocean dynamics and global climate in experiments with gradual increases of carbon dioxide. Another somewhat surprising aspect of the global-coupled GCM simulations is the appearance of some features associated with the El Niño-Southern Oscillation. Along with concurrent efforts with other types of limited-domain, dynamical coupled models, this has led to the realization that inherent unstable coupled modes exist in the climate system that are the unique product of the interactive coupling of the atmosphere and the ocean. All of these efforts are leading to the next generation of coupled ocean-atmosphere GCMs. These models will run on even faster and larger-memory computers and will have higher-resolution atmosphere and ocean components, more accurate sea-ice formulations, improved cloud-radiation schemes, and increasingly realistic land-surface processes. © 1990 Springer-Verlag."
"7003626469;7201916716;","Paleoclimatic implications of the high stand of Lake Lahontan derived from models of evaporation and lake level",1990,"10.1007/BF00209522","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025659413&doi=10.1007%2fBF00209522&partnerID=40&md5=50a2aa7da4071f1e0bde9c6bfda1c52c","Based on previous climate model simulations of a split of the polar jet stream during the late Pleistocene, we hypothesize that (1) 20-13.5 ka BP, season-to-season variation in the latitudinal maximum of the jet stream core led to enhanced wetness in the Great Basin, and (2) after 13.5 ka BP, northward movement of the jet stream resulted in increased aridity similar to today. We suggest that the enhanced effective wetness was due to increased precipitation combined with an energy-limited reduction in evaporation rates that was caused by increased summer cloud cover. A physically based thermal evaporation model was used to simulate evaporation for Lake Lahontan under various hypothesized paleoclimates. The simulated evaporation rates, together with hypothetical rates of precipitation and discharge, were input to a water balance model of Lake Lahontan. A 42% reduction in evaporation rate, combined with maximum historical rates of precipitation (1.8 times the mean annual rate) and discharge (2.4 times the mean annual rate), were sufficient to maintain Lake Lahontan at its 20-15 ka BP level. When discharge was increased to 3.8 times the present-day, mean annual rate, the ∼ 13.5 ka BP maximum level of Lake Lahontan was attained within 1400 years. A 135-m drop from the maximum level to Holocene levels was simulated within 300 years under the imposition of the present-day hydrologic balance. © 1990 Springer-Verlag."
"7005533663;7004201998;","Basis for integration of conventional observations of cloud into global nephanalyses",1990,"10.1007/BF00053665","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025198569&doi=10.1007%2fBF00053665&partnerID=40&md5=77683b0da9d6a399d71ae6c10719e12f","Water vapour is the largest and, radiatively, the most important trace gas in the Earth's atmosphere. Cloud amount and cloud optical depth feedbacks are, as yet, poorly understood and improvements in model parameterization schemes await an adequate observational data base. Satellite retrievals do not, and will not for some time, provide more than 'snapshot' (a few months to a few years) records. Conventional surface-based observations of cloudiness could complement the global coverage offered by satellite retrievals if a sound relationship between the two observational measurements could be found. Observations underline the importance of the vertical dimension of clouds which affects the observational geometries from satellites and the surface. A new basis for the relationship between the (vertical) earthview of cloud amount and the (whole dome) skycover of cloud amount has been sought. Over four and a half thousand all-sky camera photographs, representing a considerable range of seasonal and climatological conditions, have been analyzed to give rise to a database from which predictive relationships for earthview, E, and skycover, S, have been established. Cubic functions are the most soundly based both physically and empirically. We find: S=0.647+2.192 E-0.461 E2+0.037 E3 and E=-0.001+0.082 S+0.269 S2-0.019 S3 for the prediction of skycover from earthview and earthview from skycover, respectively. If earthview is required from skycover observations then E≃S could be used with little additional error. Hence, conventional surface observations of skycover could be compared directly with satellite-derived earthview values. More importantly, these results do not support the widespread assumption that conventional (surface) observations of cloud amount always exceed the earthview could retrieval. Furthermore, climate model predictions of total cloud amount may also be interpreted via these relationships. GCM-predicted layer cloud amounts can be synthesized into 'modelled E' values using the random overlap formula and hence it is possible to construct 'modelled S' values which are directly comparable with conventionally observed cloud climatologies. The 'baseline' observation of skycover by clouds therefore provides a valuable validation tool for both satellite programmes and climate models. © 1990 Kluwer Academic Publishers."
"6507587542;7406514318;","On the dependence of climate sensitivity on convective parametrization",1990,"10.1007/BF00208904","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025586845&doi=10.1007%2fBF00208904&partnerID=40&md5=15320ee2089ac680bb5d3e606e124aae","Two sensitivity experiments, in which CO2 is doubled and sea-surface temperatures are enhanced, were carried out using a general circulation model to determine the influence of the convective parametrization on simulated climate change. In the first experiment, a non-penetrative ""layer-swapping"" convection scheme is used; in the second, a penetrative scheme is used. It is found that the penetrative scheme gives the greater upper tropospheric warming (over 4.5 K compared to 4 K) and the greater reduction in upper tropospheric cloud, consistent with recent CO2 sensitivity studies. However, there is a 0.7 Wm-2 greater increase in net downward radiation at the top of the atmosphere in the experiment with the non-penetrative scheme, implying a larger tropical warming which is inconsistent with recent CO2 studies. Other possible explanations for discrepancies between recent studies of the equilibrium climate response to increasing CO2 are considered and discussed. The changes in the atmospheric fluxes of heat and moisture from the tropical continents in the model with the penetrative scheme differ from those found using the non-penetrative scheme, and those in an equilibrium experiment using the penetrative scheme. Thus, changes in circulation may explain the apparent discrepancy in the current experiments, but prescribed sea-surface temperature experiments may not provide a reliable indication of a model's equilibrium climate sensitivity. © 1990 Springer-Verlag."
"6603307411;6701752045;","Gaussian components of cloud amount frequency distributions",1990,"10.1007/BF00866204","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025585938&doi=10.1007%2fBF00866204&partnerID=40&md5=0f4e87a0f05ca3d398e4ced2e7b7d949","Interannual variability of meteorological conditions produces cloud amount sequences that statistically cannot be regarded as samples from the same population. Consequently in order to treat cloud amount distributions the traditional methods of mathematical statistics are useless. In this paper a method is presented that enables to approximate the cloud amount histograms by means of mixtures of Gaussian components. When a component can be found that is common to the histograms of different years, it may be regarded as a characteristic of a quasistationary cloudiness regime that is induced by stable meteorological conditions above the respective target area during the given period. The procedure to separate a cloud amount frequency distribution into Gaussian components is demonstrated on the basis of an example of March-May cloudiness analysis in the mid-ocean regions of the belt 0°-13.5° S. The monthly mean cloud amount data in the (500 km)2 squares have been determined from Nimbus-7 short-wave albedo measurements in 1979-1986. It has been demonstrated that even in the years that are not affected by the El Niño event the interannual variability of the autumn cloud amount histograms is essential at the 95% significance level. But separating the frequency distributions into Gaussian components, a part can be found that is common to all the autumns and, thus, may be regarded as a characteristic of the contemporary climate. © 1990 Springer-Verlag."
"7005516084;","Satellite observation of the Earth Radiation Budget and clouds",1990,"10.1007/BF00704238","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041518298&doi=10.1007%2fBF00704238&partnerID=40&md5=dd74ae64788a86b9ff2d8742b9b8c0de","We review briefly the needs of climate research for satellite observations of atmospheric and surface properties. We consider in particular the need for observations of the Earth radiation budget and clouds, the fundamental physical constraints on such observations, and the advances both in instrumentation and in data processing methodology. We note how our concepts of the role of clouds and radiation in the climate system have been refined and in some cases revised as a result of the availability of satellite observations. The ongoing (NASA) Earth Radiation Budget Experiment and the (WCRP) International Satellite Cloud Climatology Project have begun to provide new results of considerable importance. Following a description of projects for the near and not-so-near term future, we conclude with recommendations regarding the directions to be taken in planning for the global climate satellite monitoring system of the year 2000. © 1990 Kluwer Academic Publishers."
"7005516084;","Earth radiation budget and climate",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025587827&partnerID=40&md5=1ed3826fc4e500147cdb522db3dc011e","We review the role of radiative processes in climate and climate change, considering the relations between the Earth Radiation Budget and climate in the conceptual framework of relatively simple models. We note in particular the critical role of clouds and the uncertainties related to cloud radiative forcing and feedback. -Authors"
"7003666669;57210518852;7102604282;7203015939;","Model test of CCN‐cloud albedo climate forcing",1990,"10.1029/GL017i005p00607","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025657698&doi=10.1029%2fGL017i005p00607&partnerID=40&md5=92b78500d202989beb4b196515b38907","Cloud condensation nuclei (CCN) influence cloud albedo through their effect on the cloud droplet size distribution. A number of studies have evaluated the climatic impact of the CCN‐cloud albedo feedback, but all have assumed that cloud distributions, cloud thicknesses, and cloud liquid water contents would remain constant as the climate adjusted. We have tested this assumption using the Livermore version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM1). Our results indicate that there are no significant compensating changes in cloud properties that would counteract the 1.7% global albedo increase resulting from a fourfold increase in marine CCN concentration. Furthermore, when ocean surface temperatures are decreased 4° C in a manner broadly consistent with the enhanced cloud albedos, we predict an increase in cloud fraction of 3.5% and a reduction in cloud altitude, leading to a positive feedback from clouds that would imply a climate impact roughly double that calculated from cloud droplet size distribution change alone. Copyright 1990 by the American Geophysical Union."
"7005070958;","Intercomparison and interpretation of climate feedback processes in 19 atmospheric general circulation models",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025680011&partnerID=40&md5=d50c5cb95d7ee2ce0540c5f5ffc3a735","This intercomparison uses sea surface temperature change as a surrogate for climate change. The interpretation of cloud-climate interactions is given special attention. A roughly threefold variation in one measure of global climate sensitivity is found among the 19 models. The important conclusion is that most of this variation is attributable to differences in the models' depiction of cloud feedback. It is further emphasized that cloud feedback is the consequence of all interacting physical and dynamical processes in a general circlation model. The results of these processes is to produce changes in temperature, moisture distribution, and clouds which are integrated into the radiative response termed cloud feedback. -from Authors"
"7005516084;","Earth Radiation Budget and climate",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025230197&partnerID=40&md5=098fcd4e2b1513beeeea09fc938b03fa","The author reviews the role of radiative processes in climate and climate change considering the relations between the Earth Radiation Budget and climate in the conceptual framework of relatively simple models. In particular, the critical role of clouds and the uncertainties related to cloud radiative forcing and feedback is noted."
"7102841561;","Clouds and the atmospheric radiation balance",1990,"10.1177/030913339001400106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025626276&doi=10.1177%2f030913339001400106&partnerID=40&md5=6ee05ec0f03d13c931de12356f08cebd",[No abstract available]
"7202899330;7101899854;6602844274;7003468747;","The relevance of the microphysical and radiative properties of cirrus clouds to climate and climatic feedback",1990,"10.1175/1520-0469(1990)047<1742:trotma>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025621744&doi=10.1175%2f1520-0469%281990%29047%3c1742%3atrotma%3e2.0.co%3b2&partnerID=40&md5=f01f662ea51e7ffc31f104565724a915","Observations that relate the ice water content to cloud temperature are incorporated in the parameterization to introduce a temperature dependence to both albedo and emittance. The cloud properties relevant to the cloud feedback are expressed as functions of particles size re, asymmetry parameter g and cloud temperature and analyses of aircraft measurements, lidar and ground based radiometer data are used to select re and g. It was shown that scattering calculations assuming spherical particles with a distribution described by re = 16 μm reasonably matched the lidar and radiometer data. However, comparison of cloud radiation properties measured from aircraft to those parameterized in this study required values of g significantly smaller than those derived for spheres but consistent with our understanding of non-spherical particles scattering. The climate simulations revealed that the influence of cirrus cloud on climate was strongly affected by the choice of re and g: parameters that are both poorly known for cirrus. -from Authors"
"7103135455;7102015136;","Marine phytoplankton and global climate feedback - testing the hypothesis",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025589393&partnerID=40&md5=bb38b483d2775b99c3d5e62b3c3ba10a","Some attempts at testing the ""marine phytoplankton-cloud condensation nucleus-cloud albedo-climate' connection, using historical data and reports of historical data that can also be interpreted as testing this theory, have recently appeared in the literature. These suffer common problems of an ill-defined relationship between the measured property and CCN concentration, and uncertainty regarding the controling factors. We suggest that, rather than try to infer cloud nucleus data from historical data, better tests can be envisaged using contemporary measurements over the Southern Ocean. A possible procedure taking advantage of recent advances in remote sensing is advocated. -Authors"
"7005882490;7006312044;16185051500;","Particle production associated with marine clouds",1990,"10.1029/jd095id09p13917","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025656858&doi=10.1029%2fjd095id09p13917&partnerID=40&md5=e0886cc79a52b1843dcb4615738c7514","Vertical profiles of Aitken nuclei, cloud condensation nuclei, sulfate, and SO2 concentrations have been measured in the marine atmosphere under relatively clean conditions. The vertical profiles of Aitken nucleus concentrations commonly showed maximum values just above cloud tops. We interpret these measurements as evidence for the nucleation of new sulfate particles in these locations. The cloud condensation nucleus profiles are consistent with this interpretation. A theoretical analysis of the measurements, utilizing a model of homogeneous, hetermolecular nucleation, predicts that the nucleation of new sulfate particles should occur primarily in the proximity of clouds. Implications of these results for the dimethyl sulfide-cloud-climate hypothesis are discussed. -Authors"
"7005956183;","The International Cirrus Experiment (ICE) - a joint European effort",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025627695&partnerID=40&md5=74e2ad98f0740e3d6070a658d5c0b794","A large field campaign has recently been conducted over the North Sea to measure the physical properties of clouds and contrails, and those parameters that affect these properties. This expedition was part of the International Cirrus Experiment (ICE), Europe's contribution to the International Satellite Cloud Climatology Project (ISCCP). In addition to its focussing on the cloud-and-climate problem, the experiment has an important bearing on the operational estimation of wind fields from the displacement of clouds in satellite images, as it will help to improve our understanding of the relationship between cirrus-cloud displacement and prevailing wind field. -from Authors"
"7005513582;13406672500;","Comparison of cloud forcing derived from the Earth Radiation Budget Experiment with that simulated by the NCAR Community Climate Model",1990,"10.1029/jd095id08p11679","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025621056&doi=10.1029%2fjd095id08p11679&partnerID=40&md5=8786739f84a235573bbe0bf630fdcc00","Comparison between ERBE clear-sky longwave fluxes and CCM1 indicates larger outgoing flux in the model than measured by ERBE. This overestimation is ascribed to the prevalent dryness of the model. Comparison of clear sky albedo indicates good agreement over oceans and land. Comparison of shortwave cloud radiative forcing indicates deficiencies in the model where marine stratus clouds are absent. Large longwave cloud forcing over the tropical deep convective regions in Indonesia and South America are present in the model but are underestimated compared with the ERBE results. -from Authors"
"7007088807;","Observations concerning the empirical relationship of cloud shade to point cloudiness (Romania)",1990,"10.1175/1520-0450(1990)029<1358:OCTERO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025524468&doi=10.1175%2f1520-0450%281990%29029%3c1358%3aOCTERO%3e2.0.CO%3b2&partnerID=40&md5=9c46dbb7b5b190c688bdbdb4a6a13c13","Monthly average values from 29 weather stations of Romania show that, in general, point cloudiness (PC) is greater than cloud shade (CS) by as much as 0.2. Four previously proposed empirical relationships of cloud shade to point cloudiness were verified under the climate and latitudes of Romania; in all cases new coefficients of regression were determined. -Author"
"7003922138;7102875645;","Can existing climate models be used to study anthropogenic changes in tropical cyclone climate?",1990,"10.1029/GL017i011p01917","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025592062&doi=10.1029%2fGL017i011p01917&partnerID=40&md5=c299ac57d4b30a1bd1a48756f6f1fd8a","The utility of current generation climate models for studying the influence of greenhouse warming on the tropical storm climatology is examined. A method developed to identify tropical cyclones is applied to a series of model integrations. The global distribution of tropical storms is simulated by these models in a generally realistic manner. While the model resolution is insufficient to reproduce the fine structure of tropical cyclones, the simulated storms become more realistic as resolution is increased. To obtain a preliminary estimate of the response of the tropical cyclone climatology, CO2 was doubled using models with varying cloud treatments and different horizontal resolutions. In the experiment with prescribed cloudiness, the number of storm‐days, a combined measure of the number and duration of tropical storms, undergoes a statistically significant increase in the doubled‐CO2 climate. In contrast, a smaller but significant reduction of the number of storm‐days is indicated in the experiment with cloud feedback. In both cases the response is independent of horizontal resolution. While the inconclusive nature of these experimeital results highlights the uncertainties that remain in examining the details of greenhouse gas induced climate change, the ability of the models to qualitatively simulate the tropical storm climatology suggests that they are appropriate tools for this problem. Copyright 1990 by the American Geophysical Union."
"7103010852;","Earthwatch: the climate from space",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84970787301&partnerID=40&md5=c700c77ef188e5c0899b9f7d8976625f","The author first summarises the climate system, covering basic principles: the atmosphere, clouds, the oceans, land, the cryosphere and modelling. The next section covers ozone holes, the greenhouse effect and El Nino. The techniques of space observation are covered next, including orbits, remote sensing of the surface, remote soundings of the atmosphere (nadir and limb sounding). Infrared limb sounding radiometers, microwave radiometers, visible and IR imagers for the polar platform and radar altimetry are discussed in detail. Finally, space observations of ozone, sea surface temperature, polar ice, ocean surface, land surface and clouds are presented. There are 19 colour plates of satellite observations included. -J.F.Austin"
"7102604282;","Cloud Albedo, Greenhouse Effects, Atmospheric Chemistry, and Climate Change",1990,"10.1080/10473289.1990.10466699","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025412896&doi=10.1080%2f10473289.1990.10466699&partnerID=40&md5=af6019e6927000b31319e3af34f2f1c5","Changes in global atmospheric chemistry and climate are taking place as a result of observed trends in long- lived species such as CO2, CH4, N2O, and the CFCs. The continuation of these trends is expected to eventually lead to a major atmospheric warming that might profoundly affect the society we live in. Trends in short-lived species such as NOx and SOx are also suspected. These trends are not as well established, because the shorter-lived species vary spatially and temporally. Trends in NOx would be expected to lead to increases in tropospheric ozone that would add to the warming created by the other greenhouse gases. Trends in NOx could also alter tropospheric OH concentrations that could lead to changes in CH4 and some of the CFGs. On the other hand, increases in sulfur emissions may alter cloud optical properties. The changes in cloud optical properties could possibly offset the warming expected from increases in greenhouse gases, depending on the role of natural oceanic sulfur emissions. This paper summarizes recent research in these areas and the interactions of climate and atmospheric chemistry. © 1990 Air &amp; Waste Management Association."
"6508285452;","North Sea climate based on observations from ships and lightvessels",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040889662&partnerID=40&md5=d0547a8d02dcaccd9a843d3569a42565","The methods and reporting procedures are described for air temperature, sea surface temperature, air pressure, cloud cover, precipitation, visibility and waves. The air and sea surface temperatures are then presented in terms of geographical distribution, annual variation, variability at a certain place, and variation over the period 1885-1980. Visibility data as a function of geographical distribution, annual variation, diurnal variation, relation to wind force and direction, and persistence are presented. Wind and waves roses are given, along with probabilities of extreme high wind speeds and extreme wave heights. -J.F.Austin"
"57203258256;7004570479;","The sensitivity of a coupled atmospheric-oceanic model to variations in the albedo and absorptivity of a stratospheric aerosol layer",1990,"10.1029/JD095iD07p09941","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025625144&doi=10.1029%2fJD095iD07p09941&partnerID=40&md5=fd24f715463ad3f3fec6156ea91bb253","Considerable uncertainty exists regarding the precise physical parameters of a smoke or aerosol cloud that would be injected into the lower stratosphere by a catastrophic event such as a nuclear war, a major volcanic eruption, or an asteroid impact. In this paper, the sensitivity of the sea surface temperature of a one-dimensional coupled atmospheric-oceanic model to variations in the albedo and absorptivity of an aerosol cloud introduced into the lower stratosphere is examined. Zonally averaged results are produced for two latitudes in the southern hemisphere. The temperature response of the oceans to forcings by a cloud with realistic aerosol properties is examined, with particular emphasis on the impact on the surface climate on time scales of 6 months to 2yr. -Authors"
"55667068400;","Measurement of concentrations of natural ice nuclei",1990,"10.1016/0169-8095(90)90024-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025690994&doi=10.1016%2f0169-8095%2890%2990024-7&partnerID=40&md5=3f55157e1174bf30e967e448f2fc6089","If the currently forecast global warming occurs, the distribution of clouds and their properties are likely to change also and interact with the warming. The distribution of precipitation will also be affected. One known influence on cloud properties and the formation of precipitation is the concentration of airborne particles on which ice forms in supercooled clouds, known as ice nuclei. The possibility that their concentrations may also change with time must be examined if the predictions of warming are to be accurate. If they are biogenic origin, as now seems possible, there is the possibility of feedback between climate and ice nucleus production. It is argued here that there is at present only one feasible method of measuring ice nucleus concentrations on a sufficiently wide scale, with sufficient frequency and at various altitudes. In this method, the particles are caught on membrane filters and the ice nuclei detected in a thermal diffusion chamber. The defects of this technique are reviewed and it is concluded that with suitable precautions it is adequate for the task. © 1990."
"7005691764;","Operational soil moisture estimation for the midwestern United States",1990,"10.1175/1520-0450(1990)029<1158:OSMEFT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025587884&doi=10.1175%2f1520-0450%281990%29029%3c1158%3aOSMEFT%3e2.0.CO%3b2&partnerID=40&md5=e0ab69d59a74b2a3ddce72679d1aab8f","A soil moisture monitoring capability is developed using a multilayer soil water balance model which incorporates daily weather data to calculate precipitation, soil evaporation, plant transpiration, runoff and drainage through the soil profile. The effects of vegetation on soil evaporation and plant transpiration are incorporated through the use of a model for the growth and development of corn. Data requirements include daily observations of maximum temperature, minimum temperature, and precipitation and hourly observations of cloud cover, humidity, and wind speed; these data are collected in real time and aggregated on a climate division scale. The average characteristics of the dominiant soils in each climate division are used as representative of that climate division. Historical soil moisture estimates using this same model were generated for the period 1949-89. -from Author"
"7103135455;","Cloud condensation nuclei over the Southern Ocean",1990,"10.1029/GL017i010p01565","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025692741&doi=10.1029%2fGL017i010p01565&partnerID=40&md5=43cddd1f9ae8e7c116d4e6f556d5f314","The basis of a cloud condensation nucleus (CCN) climatology program has been in place at Cape Grim (Tasmania) since 1982. This has shown both marked seasonal variation and evidence of interannual variation in CCN concentration. CCN concentrations have been found to be substantially understandable in terms of the condensation or Aitken nucleus (CN) concentration and size. Whether CCN concentrations are systematically changing in response to climate change and/or increasing anthropogenic sulfur emission is an unresolved question. Although present CCN concentrations are higher than those reported for clean oceanic regions two decades earlier, the data do not allow confident conclusions about the cause. Copyright 1990 by the American Geophysical Union."
"6507984725;8225183400;7004189939;7102244456;","Is recent climate change across the United States related to rising levels of anthropogenic greenhouse gases?",1990,"10.1029/jd095id10p16617","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025691740&doi=10.1029%2fjd095id10p16617&partnerID=40&md5=07bfd6aee6fdacdca8f3b1f7c25adfc6","Global warming as a result of rising concentrations of anthropogenic greenhouse gases is predicted by current climate models. During the period 1948-1987, the concentration of anthropogenic greenhouse gases increased by more than 30%, and the mean annual temperature of the northern hemisphere increased by about 0.15°C. The mean annual temperature of the contiguous United States, however, does not show any significant trend. We conclude that either the recent changes of temperature, cloud amount, sunshine and precipitation over the United States are as yet unrelated to the increasing anthropogenic greenhouse gases, or that the transient response of regional climates to the greenhouse effect is not proportional to the modeled difference between the 1 × CO2 and 2 × CO2 equilibrium climates. -from Authors"
"7006977548;55269801100;","The greenhouse effect, stratospheric ozone, marine productivity, and global hydrology: feedbacks in the global climate system",1990,"10.1007/978-94-009-0701-0_1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025589706&doi=10.1007%2f978-94-009-0701-0_1&partnerID=40&md5=e6a8719a47f4f034cb92f674314fa288","Recognized feedbacks act through two important loops involving changes in atmospheric chemistry, UV-B radiation at the earth's surface, and marine productivity. Reliable predictions of future changes in global and regional climate require an understanding of the direction, magnitude and time constants of the various climatic and biochemical feedback processes. Changes in the amount and distribution of precipitation can also have important feedback effects on soil moisture, vegetation, cloudiness, ground and cloud albedo, ocean salinity (through changes in evaporation and runoff), bottom water formation and productivity. -from Authors"
"7404296283;7004899626;7006506458;57207518890;7102681042;","Discrete angle radiative transfer: 3. Numerical results and meteorological applications",1990,"10.1029/jd095id08p11729","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025678003&doi=10.1029%2fjd095id08p11729&partnerID=40&md5=b640aaf221ec7c9d38a29e2b4351e882","Additional numerical results are obtained for a simple class of scale invariant (fractal) clouds that arises when modeling the concentration of cloud liquid water into ever smaller regions by advection in turbulent cascades. These so-called random ""β models' are (also) characterized by a single fractal dimension. Both open and cyclical horizontal boundary conditions are considered. These and previous results are contrasted with plane-parallel predictions, and measures of systematic error are defined as ""packing factors' which are found to diverge algebraically with average optical thickness and are significant even when the scaling behavior is very limited in range. Several meteorological consequences, especially concerning the ""albedo paradox' and global climate models, are discussed, and future directions of investigation are outlined. -from Authors"
"7201783608;7004266190;","A mass flux convection scheme with representation of cloud ensemble characteristics and stability-dependent closure",1990,"10.1175/1520-0493(1990)118<1483:AMFCSW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025590082&doi=10.1175%2f1520-0493%281990%29118%3c1483%3aAMFCSW%3e2.0.CO%3b2&partnerID=40&md5=2d0d8781532e70f4778bf0c8ec03388e","The convection scheme used at the UK Meteorological Office in large-scale numerical models is described. The scheme uses a ""bulk' cloud model to represent an ensemble of convective clouds and aims to represent shallow, deep and midlevel convection. A simple closure is employed, the initial convective mass flux being related to the stability of the initial convecting layer. The ability of the scheme to represent convective processes in a variety of situations is evaluated. The performance of the scheme in an 11-layer atmospheric general circulation model used in climate research at the UK Meteorological Office is also evaluated by comparing aspects of the simulated tropical flow from a recent 4-year integration with observed data. The scheme simulates the main areas of latent heat release and their variation throughout the year, although the Indian Monsoon is poorly simulated. -from Authors"
"7004037177;","Recreation climate assessment",1990,"10.1002/joc.3370100110","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025152042&doi=10.1002%2fjoc.3370100110&partnerID=40&md5=e1d6d81422db37f12cbf5fbdb4ce4e9e","The study examines methods for assessing the atmospheric resource component of recreation environments. Beach use is selected as it is a highly weather sensitive recreational activity. The study area is King's Beach in Queensland, Australia. The nature of the relationship between beach climate and the enjoyment of recreational pursuits is taken to be a function of thermal, physical, and aesthetic components of the atmospheric environment. A body‐atmosphere heat‐budget model is used to integrate and isolate the thermal component of beach weather and enable identification of important non‐thermal recreational resource attributes of the atmosphere. Beach‐user sensory perception of on‐site atmospheric conditions expressed verbally is used to assess the physical and aesthetic components of the atmospheric environment. The immediate thermal environment of the beach user is the main contributing factor to assessments of the desirability of on‐site meteorological conditions, followed by the non‐thermal effects of cloud and wind. Rainfall events of half‐hour duration or longer have an overriding effect. Copyright © 1990 John Wiley & Sons, Ltd"
"7004563994;7003274944;","Climatic factors and tree stature in the elfin cloud forest of Serrania de Macuira, Colombia",1990,"10.1016/0168-1923(90)90127-R","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025586783&doi=10.1016%2f0168-1923%2890%2990127-R&partnerID=40&md5=d3c18f406b3c34f8d67e8e5f7f658667","Cloud cover, solar radiant flux density, temperature and relative humidity regimes were studied along the altitudinal gradient of Serrania de Macuira (865 m), Guajira, Colombia. The regional climate at Macuira is characterized by the presence of small cumulus clouds, persistent trade winds from the northeast, and low and highly seasonal rainfall. During the day time, the clouds remain above the highest peaks of the Serrania, decreasing radiation, air temperature, relative humidity and evaporation in relation to the lowlands. At night the clouds come into contact with the forest, supplying water by means of mist and fog interception. Owing to this pattern, the cloud forest trees on top of the mountain experience low air saturation deficits only during the night, early morning and late afternoon. This shows that the low stature of trees in this forest is not the result of an uninterrupted low saturation deficit that would inhibit mineral pumping by means of transpiration. The soil temperature gradient in Macuira was steeper than that reported for higher and more massive mountains of the tropics. This steeper gradient is the result of high temperatures in the dry lowlands around the mountain. Strong winds seem to be the cause of the reduction in tree stature in the more exposed slopes and ridges, but are not the general explanation for small trees in this forest. Wind speed is much lower in gullies than on ridges and slopes, nevertheless, trees are also small. We think that the climatic factor that has a more pronounced effect on the physiognomy of this forest is cloud water. The effects of high water content of the soil on soil chemistry, would be worth investigating as a general explanation for the small stature of these trees. © 1990."
"7004942632;7006385747;7006630889;24322005900;","Radiative forcing of climate",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025528135&partnerID=40&md5=f5eaf1d81e642a2293f8a5fc53a461a6","The major contributors to increases in radiative forcing since pre-industrial times are CO2 (61%), CH4 (17%), N2O (4%) and CFCs (12%). The most recent decadal increase in radiative forcing is attributable to CO2 (56%), CH4 (11%), N2O (6%) and CFCs (24%). Stratospheric H2O is estimated to have contributed 4%. Man-made sulphur emissions, which have increased in the Northern Hemisphere over the last century, affect radiative forcing by forming aerosols and influencing the radiative properties of clouds so as to cool the earth. It is conceivable that this forcing has been of a comparable magnitude, but of opposite sign, to the greenhouse forcing. -J.F.Austin"
"7102408882;6701501555;6603695574;","Canada's operational Doppler radar",1990,"10.1007/978-94-009-0551-1_31","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025587332&doi=10.1007%2f978-94-009-0551-1_31&partnerID=40&md5=0dca3755bab9e65c8d39c23fe60941bc","The King Weather Radar Research Station of the Atmospheric Environment Service (AES), located north of the metropolitan Toronto area in Southern Ontario, is a component of the Canadian weather service radar network. The only Doppler weather radar in the country, it was instituted as part of the research program of the Cloud Physics Division of AES and is a first phase of Canada's Dopplerization plan. The main objectives for this radar were to identify operational uses of Doppler radars in the Canadian climate, to determine and test the functional and technical requirements for an operational Doppler radar, to develop Doppler radar expertise and to initiate the training of operational meteorologists in the use of Doppler radars. -from Authors"
"55192899700;7004920873;24388771700;7004063331;","Greenhouse gases and aerosols",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025587274&partnerID=40&md5=5d3e969d5d655f48f55e679627df52ab","The Earth's climate is dependent upon the radiative balance of the atmosphere, which in turn depends upon the input of solar radiation and the atmospheric abundances of radiatively active trace gases (ie, greenhouse gases), clouds and aerosols. Since the industrial revolution the atmospheric concentrations of several greenhouse gases, ie, carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs), nitrous oxide (N2O), and tropospheric ozone (O3), have been increasing, primarily due to human activities. Several of these greenhouse gases have long atmospheric lifetimes, decades to centuries, which means that their atmospheric concentrations respond slowly to changes in emission rates. In addition, there is evidence that the concentrations of tropospheric aerosols have increased at least regionally. -Authors"
"6602725432;7004479957;56979463400;56158328200;7004432098;","Buoyancy reversal and cloud‐top entrainment instability",1990,"10.1002/qj.49711649309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025584941&doi=10.1002%2fqj.49711649309&partnerID=40&md5=3a9c3bb52fa885f0603bfddc808112e7","In 1980, Randall suggested that cloud top entrainment instability, a runaway positive feedback between mixing, evaporative cooling and entrainment, may cause the transition from the subtropical stratocumulus layers, frequently observed over the cold water of the eastern oceans, to tradewind cumulus. Predicting how the mean position of this transition, and the associated large change in albedo, would vary with, and feed back on, a change in climate is important for any credible model of the climate system. We have used numerical and laboratory simulations, as well as field observations, to study entrainment in buoyancy‐reversing systems. We consider a system in which an upper fluid stably overlies a second lower fluid; but some mixtures are less buoyant than either fluid. the laboratory results show that buoyancy reversal does not cause runaway ‘explosive entrainment’ unless D (the ratio of the density difference between the most cooled mixed parcel and the lower fluid to the density difference across the unmixed layers, a measure of CEI potential) exceeds 1.3, which is far greater than the range of D observed in stratocumulus. For D below this threshold, buoyancy reversal leads to weak circulations rather reminiscent of Rayleigh‐Bénard convection in the lower layer, but only slightly distorts the interface. For D > 1.3 an entrainment tongue of upper fluid penetrates a sizable fraction of the depth of the lower layer and entrainment is explosively rapid. Numerical experiments suggest that even when 0 < D < 1.3, entrainment can break up idealized subtropical marine stratocumulus within about an hour if radiation and surface fluxes are removed, but comparison of numerical simulations with the laboratory experiments suggests that the numerically simulated entrainment rate may be substantially too large in this regime owing to the inability to accurately produce and resolve the entraining eddies. Our observations of stratocumulus from FIRE typically had a strong stable layer above the cloud top inversions, leading to some ambiguity in defining D, but clearly show that stable stratocumulus layers often have 0 < D < 0.2. We suggest that sudden breakup of stratocumulus due to runaway entrainment is unlikely, but evaporatively enhanced entrainment may aid the transition from stratocumulus to tradewind cumulus in conjunction with some other mechanism, such as short‐wave absorption by liquid water, that can help dynamically decouple the cloud layer from the surface layer. Copyright © 1990 Royal Meteorological Society"
"7405586876;","Precambrian evolution of the climate system",1990,"10.1016/S0031-0182(12)80005-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025573839&doi=10.1016%2fS0031-0182%2812%2980005-8&partnerID=40&md5=3106e2168c0930240b0220e21f6a4487","Climate is an important environmental parameter of the early Earth, likely to have affected the origin and evolution of life, the composition and mineralogy of sedimentary rocks, and stable isotope ratios in sedimentary minerals. There is little observational evidence constraining Precambrian climates. Most of our knowledge is at present theoretical. Factors that must have affected the climate include reduced solar luminosity, enhanced rotation rate of the Earth, an area of land that probably increased with time, and biological evolution, particularly as it affected the composition of the atmosphere and the greenhouse effect. Cloud cover is a major uncertainty about the early Earth. Carbon dioxide and its greenhouse effect are the factors that have been most extensively studied. This paper presents a new examination of the biogeochemical cycles of carbon as they may have changed between an Archean Earth deficient in land, sedimentary rocks, and biological activity, and a Proterozoic Earth much like the modern Earth, but lacking terrestrial life and carbonate-secreting plankton. Results of a numerical simulation of this transition show how increasing biological activity could have drawn down atmospheric carbon dioxide by extracting sedimentary organic carbon from the system. Increasing area of continents could further have drawn down carbon dioxide by encouraging the accumulation of carbonate sediments. An attempt to develop a numerical simulation of the carbon cycles of the Precambrian raises questions about sources and sinks of marine carbon and alkalinity on a world without continents. More information is needed about sea-floor weathering processes. © 1990, Elsevier Science Publishers B.V.. All rights reserved."
"57212700015;","Weather and the sale of goods and services",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025676860&partnerID=40&md5=ecc1b46516b9c52f64be816d1b0175c6","The sensitivities of some industrial sectors to variability of weather and climate are already well known. For example, in the United Kingdom detailed correlations between the demand for electricity and weather elements such as temperature, windiness, cloud cover and precipitation are well established; similar data exist for the gas and water supply industries. Studies of the variation of demand with weather, Weather Sensitivity Analyses (WSAs), can be applied to products and services from other market sectors, for example the retail industry, road transport and insurance groups. The purpose of this paper is to give a brief description of the techniques involved and a few examples of recent applications. -from Author"
"57206546845;7003666669;7401785020;7003828316;","Global environmental effects of impact-generated aerosols; Results from a general circulation model",1990,"10.1130/SPE247-p263","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879638589&doi=10.1130%2fSPE247-p263&partnerID=40&md5=9eef86470d44608e947e10950ab0209e","Interception of sunlight by the high-altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to our three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans substantially mitigates land surface cooling, an effect that one-dimensional models cannot quantify. On the other hand, the low heat capacity of the GCM land surface allows temperatures to drop more rapidly in the initial stages of cooling than in the one-dimensional model study. These two differences between three-dimensional and one-dimensional model simulations were noted previously in studies of ""nuclear winter""; GCM-simulated climatic changes in the Alvarez-inspired scenario of ""asteroid/ comet winter,"" however, are more severe than in ""nuclear winter"" because the assumed aerosol amount is large enough to intercept all sunlight falling on Earth. Impacts of smaller objects-which would occur much more frequently than the Cretaceous/Tertiary event deduced by Alvarez and coworkers-could also lead to dramatic, though of course less severe, climatic changes, according to our GCM. Our conclusion is that it is difficult to imagine an asteroid or comet impact leading to anything approaching complete global freezing, but quite reasonable to assume that impacts at the Alvarez level, or even smaller, dramatically alter the climate in at least a ""patchy"" sense."
"35461763400;","Ocean-atmosphere interactions in the global biogeochemical sulfur cycle",1990,"10.1016/0304-4203(90)90059-L","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025585827&doi=10.1016%2f0304-4203%2890%2990059-L&partnerID=40&md5=b2f4eb2fda2d2e6d5e241ae299e8f501","Sulfate is taken up by algae and plants and then reduced and incorporated into organosulfur compounds. Marine algae produce dimethylsulfonium propionate (DMSP), which has an osmoregulating function but may also be enzymatically cleaved to yield the volatile dimethylsulfide (DMS). Attempts to identify the variables which control the oceanic production of DMS have shown that there are no simple relationships with algal biomass or primary productivity, but suggest that the concentration of DMS in the ocean is regulated by a complicated interplay of algal speciation and trophic interactions. Part of the biogenically produced DMS diffuses into the atmosphere, where it is oxidized, mostly to aerosol sulfate. The ability of these aerosol particles to nucleate cloud droplets, and thereby influence the reflectivity and stability of clouds, forms the basis of a proposed geophysiological feedback loop involving phytoplankton, atmospheric sulfur, and climate. Carbonylsulfide (COS) is produced photochemically from dissolved organic matter in seawater. The mechanism of this reaction is still unknown. Diffusion of COS from the ocean to the atmosphere is a globally significant source of this gas, which participates in the stratospheric ozone cycle. Hydrogen sulfide and carbon disulfide are produced in the surface ocean by still unidentified processes, which appear to be related to biogenic activity. For these gases, the oceans are a minor source to the troposphere. © 1990."
"6602826269;","Canyon geometry, the urban fabric and nocturnal cooling: A simulation approach",1990,"10.1080/02723646.1990.10642404","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025590317&doi=10.1080%2f02723646.1990.10642404&partnerID=40&md5=734ba1d24301474cf1ecfabbbbe55e3b","A simulation model for surface cooling in urban street canyons under calm conditions is described, based upon a simplified energy budget for the canyon facets containing only the net longwave and substrate heat flux densities. The former term is evaluated from the canyon radiation budget model of Arnfield (1976), the latter by numerically approximating the Fourier heat conduction equation. Equilibrium temperatures evolve through the nocturnal period for specified canyon and incoming longwave irradiance characteristics. Numerical experiments conducted with the model show that canyon geometry alone exerts a significant effect on cooling rates and, hence, on heat island intensity. Construction materials and internal building climate control tend to enhance spatial variations in nocturnal temperatures. The effects of wall thickness, sky radiance distribution and cloud cover also are investigated. Results show qualitative and quantitative correspondences with previous field and scale-model studies. Sources of error and desirable model refinements are discussed. © 1990 Taylor & Francis Group, LLC."
"7201612805;7202409757;16503203800;","Climatic control of lake levels in the Lake Michigan and Lake Huron basins",1990,"10.1130/SPE251-p75","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879581609&doi=10.1130%2fSPE251-p75&partnerID=40&md5=7d357f26b62793a3c47fcb9ac9f5218d","The various elevations at which the lakes in the Michigan and Huron basins stood during the Holocene Epoch were previously thought to be the result of isostatic uplift of the northern outlets and discontinuous erosion of the southern outlets. Lake-level fluctuations of smaller magnitude, however, were caused by climatic changes. Correlation of climatic variables and lake-level variations over the past 100 years indicate that high lake levels occurred during cold periods when arctic air frequently converged over the Great Lakes with warm moist air from the Gulf of Mexico, causing increased rainfall. At the same time, increased cloud cover decreased evaporation. In addition, lower temperatures caused more winter precipitation to be held in storage in the basin as snow and ice, later to be made available for run-off during the spring. Major periods of climatically induced high lake levels can be recognized where sediments along the beach were eroded during the high levels, and in areas behind the beach where streams aggraded, active marshes formed, and soils formed on eolian sands. Radiocarbon dates of organic material that accumulated in these areas during high-water periods, coupled with analysis of the historic record of lake-level fluctuations, indicate that water level has varied cyclically, with a short 100- to 150-year cycle superimposed on a longer 400- to 500-year one."
"7006466769;7004309425;6602667669;","Analytically processed Landsat TM images for visual geological interpretation in the northern Scandinavian Caledonides",1990,"10.1016/0924-2716(90)90034-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025631852&doi=10.1016%2f0924-2716%2890%2990034-9&partnerID=40&md5=b207ca918c3f864d7cdc75465a01d0a9","The best results for lithogical mapping and mineral exploration using remote sensing have hitherto been achieved in areas with arid or semi-arid climates, residual soils and with little or no vegetation cover. This study concerns the applicability of Landsat TM data for lithological mapping in a part of the northernmost Scandinavian Caledonides, dominated by bare rock but with frequent occurrence of vegetation-covered glacial deposits. In order to efficiently use existing image enhancement methods, e.g., principal component analysis and ratios, it is important to concentrate, as far is possible, on the spectral characteristics of the bedrock within the areas to be interpreted. The statistics for the processed images are then concentrated on bare rock and spectrally similar objects like soils. Various methods for image enhancement for geological purposes are discussed, and procedures for the removal of picture elements influenced by vegetation, water, clouds, snow and deep shadows are described. © 1990."
"7006175268;","Decadal‐scale changes of the circulation in the tropical atlantic sector associated with Sahel drought",1990,"10.1002/joc.3370100504","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025679899&doi=10.1002%2fjoc.3370100504&partnerID=40&md5=69586dfd65db705fab352d061ba20616","Trends in the general circulation setting during 1948–1983 accompanying the progressive aggravation of drought in sub‐Saharan Africa are investigated from ship observations over the tropical Atlantic and surface station records in western Africa. Decadal‐scale circulation changes in the Atlantic sector include a pressure rise over the tropical North Atlantic; southward displacement of the near‐equatorial wind confluence and associated maximum cloud belt; acceleration of the north‐east trades and possibly a strengthening of the South Atlantic trades, along with increasing cloudiness in the equatorial zone; increasing cloudiness over the tropical North Atlantic and Central American seas; and cooling of surface waters in a band across the tropical North Atlantic contrasting with warming in the South Atlantic. These changes occurred in all seasons, but were most pronounced at the height of boreal summer. Records at land stations in western Africa show that near the coasts the temperature and pressure trends are consistent with the adjacent ocean areas. In the interior of sub‐Saharan Africa, warming trends prevail in boreal summer, presumably as a direct consequence of reduced inflow of cool maritime monsoon air; the concomitant downward pressure trends at continental stations in sub‐Saharan Africa may reflect the hydrostatic effect of increasing temperature. In contrast to boreal summer, slight cooling trends and pressure rises prevail in the interior during winter. In the course of the past four decades, the near‐equatorial wind confluence over the eastern Atlantic migrated southward by 200 km in July–August and 150 km for the rainy season as a whole. Given the steep meridional precipitation gradients across the Sahel, these circulation shifts are large enough to account for the observed downward trend in Sahel rainfall. Copyright © 1990 John Wiley & Sons, Ltd"
"26642895800;7004152561;","The botanical response of the atacama and peruvian desert floras to the 1982-83 el niño event",1990,"10.1016/S0422-9894(08)70047-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956854656&doi=10.1016%2fS0422-9894%2808%2970047-3&partnerID=40&md5=d46f75a008d21aacf687d71ef520cb90","The Atacama and Peruvian Deserts form a continuous belt along the western escarpment of the Andes for more than 3,500 km from the Peru/Ecuador border (5°00's) to northern Chile (29°55'S). This region owes its severe aridity to a constant temperature inversion generated, in part, by the cool, north-flowing Humboldt (Peruvian) Current. The atmospheric influences associated with a positionally stable, subtropical anticyclone result in a mild, uniform coastal climate and regular formation of thick stratus clouds below 1,000 m during the winter months. Where coastal topography is low and flat, this stratus layer dissipates inward over broad areas with little biological impact. However, where small isolated mountains or steep coastal slopes are present, this stratus layer forms a fog zone concentrated against the hillsides. These moist fogs allow for the development of rich fog-zone vegetation termed lomas formations. These floristic assemblages essentially function as terrestrial islands separated by hyperarid habitat where plant life is completely absent or virtually so, with the exception of Cactaceae or terrestrial Tillandsia species. Significant desert rains occur only in association with rare, but recurrent, El Niño perturbations. What was estimated as the most severe El Niño of the century began in June of 1982. By early 1983, rains had moved down the length of coastal Peru and into northern Chile, and showers continued sporadically through June 1983. Botanical fieldwork throughout the Peruvian lomas in 1983 indicated the presence of a rich bloom. Species number and density had not been at such heights since a major El Niño event in 1925. The dynamics of lomas endemism and of how plants came to colonize the fog-island archipelago are potentially related to rare episodes of El Niño rainfall. © 1990, Elsevier B.V. All rights reserved."
"6602350829;","The dynamic greenhouse: Feedback processes that may influence future concentrations of atmospheric trace gases and climatic change",1989,"10.1007/BF00134964","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024336086&doi=10.1007%2fBF00134964&partnerID=40&md5=a805a050c8fdb41a1cd729c4dc344ded","The sensitivity of the climate system to anthropogenic perturbations over the next century will be determined by a combination of feedbacks that amplify or damp the direct radiative effects of increasing concentrations of greenhouse gases. A number of important geophysical climate feedbacks, such as changes in water vapor, clouds, and sea ice albedo, are included in current climate models, but biogeochemical feedbacks such as changes in methane emissions, ocean CO2 uptake, and vegetation albedo are generally neglected. The relative importance of a wide range of feedbacks is assessed here by estimating the gain associated with each individual process. The gain from biogeochemical feedbacks is estimated to be 0.05-0.29 compared to 0.17-0.77 for geophysical climate feedbacks. The potentially most significant biogeochemical feedbacks are probably release of methane hydrates, changes in ocean chemistry, biology, and circulation, and changes in the albedo of the global vegetation. While each of these feedbacks is modest compared to the water vapor feedback, the biogeochemical feedbacks in combination have the potential to substantially increase the climate change associated with any given initial forcing. © 1989 Kluwer Academic Publishers."
"6603417019;7003371535;","Current problems in the stratocumulus-topped atmospheric boundary layer",1989,"10.1007/BF00120843","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024483740&doi=10.1007%2fBF00120843&partnerID=40&md5=59c1f601b7a50d289262cd32a8903b65","Extended sheets of stratocumulus (Sc) in the upper part of the atmospheric boundary layer (ABL) often occur under appropriate meteorological conditions. These cloud decks are important both in climate studies and in weather forecasting. We review the current knowledge of the turbulent structure of the ABL capped by a cloud deck, in the light of recent observations and model studies. The most important physical processes determining this structure are longwave radiative cooling at cloud top, shortwave radiative wanning by absorption in the cloud, surface buoyancy flux, and wind shear in the ABL. As a result, turbulence can cause entrainment against the buoyancy jump at cloud top. In cases where only longwave radiative fluxes and surface buoyancy fluxes are important, the turbulent structure is relatively well understood. When shortwave radiative fluxes and/or wind shear are also important, the resulting turbulent structure may change considerably. A decoupling of the cloud from the sub-cloud layer or of the top of the cloud from the rest of the ABL is then regularly observed. In no cases are the details of the entrainment at cloud top understood well enough to derive a relatively simple formulation that is consistent with observations. Cloud-top entrainment instability may lead to the break-up of a cloud deck (but also to cloud deepening). The role of mesoscale circulations in determining fractional cloudiness is not yet well understood. © 1989 Kluwer Academic Publishers."
"7006393951;6701324864;","Modelling of cloud formation due to air-sea interactions in an energy-active zone",1989,"10.1007/BF00120841","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024571989&doi=10.1007%2fBF00120841&partnerID=40&md5=46874c7ab969cddbee7b00e0fc7b50fe","A mesoscale 3D numerical model is described, with which detailed calculations have been made of turbulence and wind characteristics in the atmospheric boundary layer (ABL), as well as cloud particle size distribution, longwave and solar radiation fluxes and flux divergences, and atmosphere-ocean heat exchange. Based on numerical experiments simulating winter conditions of the Newfoundland energy-active zone of the ocean (EAZO), atmosphere-ocean energy exchange is investigated. It is shown that the basic mechanisms for the EAZO formation involve the following processes: (i) at the hydrological front between cold and warm ocean currents, the fluxes of sensible and latent heat grow significantly; (ii) at this front, in a particular synoptic situation, overcast low-level cloudiness forms, screening solar radiation so that in winter, the radiation budget at the front is reduced, and the radiative flux into the ocean is less than the energy release to the atmosphere; (iii) frequent occurrence of such synoptic situations with cloudiness decreases the oceanic enthalpy and creates negative SST anomalies. The transport of these anomalies by currents to the western coasts of the continents causes anomalies of weather and climate. © 1989 Kluwer Academic Publishers."
"7004169476;","MODELLING CLOUD FEEDBACKS ON CLIMATE CHANGE",1989,"10.1002/j.1477-8696.1989.tb07057.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024782468&doi=10.1002%2fj.1477-8696.1989.tb07057.x&partnerID=40&md5=184b9607b0f5caeb63f8e012d0fbdcbd",[No abstract available]
"7202208382;","Cloud parameterization for climate modeling: Status and prospects",1989,"10.1016/0169-8095(89)90025-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024798881&doi=10.1016%2f0169-8095%2889%2990025-2&partnerID=40&md5=cedc55feba17baad51847f1403e372f1","The current status of cloud parameterization research is reviewed. It is emphasized that the upper tropospheric stratiform clouds associated with deep convection are both physically important and poorly parameterized in current models. Emerging parameterizations are described in general terms, with emphasis on prognostic cloud water and fractional cloudiness, and how these relate to the problem just mentioned. © 1989."
"7409924037;7409615830;","The role of cloud microphysical processes in climate: an assessment from a one-dimensional perspective",1989,"10.1029/jd094id06p08599","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024845135&doi=10.1029%2fjd094id06p08599&partnerID=40&md5=8d7d14d85177cb24d8139ed0f88f9727","We illustrate that the rate of precipitation generation is directly proportional to the fourth power of this radius. A doubling of CO2 is used as the radiative forcing. If the perturbed mean cloud particle radii for model high, middle, and low clouds are less than the climatological mean values, precipitation decreases because of the presence of smaller cloud particles, leading to an increase in the cloud liquid water content. Cloud solar albedo effects are enhanced, resulting in a reduction of temperature increases due to CO2 doubling (negative feedback). If, however, the perturbed mean cloud particle radii are larger than the climatological mean values, the availability of larger cloud particles would increase precipitation, leading to a decrease in the cloud liquid water content. The temperature increase in the case of CO2 doubling is amplified because of a reduction of cloud solar albedo effects (positive feedback). -from Authors"
"35619149500;7406741310;","A study on cloud-radiation interaction",1989,"10.1016/0273-1177(89)90145-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45249131030&doi=10.1016%2f0273-1177%2889%2990145-2&partnerID=40&md5=bdb39ff11d6f8de534dab4710515a64e","Most empirical studies estimating the climate sensitivity due to cloud amount are based on calculating a cloud sensitivity parameter by means of satellite measurements. A different way to estimate the interaction between clouds and radiation is to determine the effect of radiative heating and cooling by clouds on the generation of available potential energy (GAPE). This provides a measure of the influence of clouds on the general circulation. The radiative contribution of clouds to the GAPE is given by the net cloud generated radiative heating (CGRH) and an efficiency factor. The CGRH, parameterized in terms of cloud type, height, and optical depth, can be estimated from satellite measurements. The efficiency factor is only a function of the temperature distribution of the atmosphere. Thus, taking satellite measurements as for instance those of the ISCCP, the radiative impact of clouds on the general circulation can be inferred. © 1989."
"7102127179;7003899619;","An analysis of cloud radiation forcing as calculated from ERBE, AVHRR and Nimbus-7 ERB and cloud data",1989,"10.1016/0273-1177(89)90154-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45249126049&doi=10.1016%2f0273-1177%2889%2990154-3&partnerID=40&md5=d06a045b67ebe9bb066a308a3ae26e9a","Longwave cloud radiative forcing, defined as the cloud free flux minus the average flux has been calculated using radiation budget data from NOAA operational satellites, ERBE (Earth Radiation Budget Experiment) and Nimbus-7 cloud and radiation budget observations. Each satellite data set has unique characteristics and different analysis procedures were used for obtaining the cloud forcing from each set. Longwave cloud forcing was computed globally on a 2.5° latitude/longitude grid. An intercomparison of results indicates that the estimates of cloud forcing, while showing some differences, exhibit a high degree of consistency in both magnitude and spatial distribution. This suggests that we can obtain a reasonably accurate depiction of spatial and temporal variability of the longwave cloud forcing suitable for climate studies. A method for calculating cloud forcing anomalies from anomalies in outgoing longwave radiation, available from NOAA operational satellites, is proposed. © 1989."
"6603892183;6604000335;7202632582;","The influence of boundary layer clouds on radiation: A review",1989,"10.1016/0169-8095(89)90019-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024783359&doi=10.1016%2f0169-8095%2889%2990019-7&partnerID=40&md5=ce1ab25280eb2df5c231c9ab5a57ff91","The influence of low-level clouds on the radiation field is reviewed from the points of view of (1) their representation in climate models, and (2) the complex interaction between cloud dynamics and radiation. From the first point of view, the main problem in the derivation of the radiative impact of clouds is to adequately characterize their radiative properties in terms of predictable quantities such as liquid water content and to determine to what extent and how their spatial structure affects their radiative properties. The results of field measurements of radiative properties of various cloud systems are reviewed and compared with theoretical calculations. Special attention is given to the shortwave absorption and the observations referenced in the literature are critically examined. The influence of cloud shape for finite-size clouds is considered together with that of horizontal heterogeneities on the bulk radiative properties of cloud layers. © 1989."
"7004034323;","A GCM parameterization for the shortwave radiative properties of water clouds",1989,"10.1175/1520-0469(1989)046<1419:AGPFTS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024824610&doi=10.1175%2f1520-0469%281989%29046%3c1419%3aAGPFTS%3e2.0.CO%3b2&partnerID=40&md5=4fa640c551d75c3cda1887614f6d1e22","It employs the simple relationhips for the optical depth, single scatter albedo and symmetry parameter of cloud drops as functions of the cloud liquid water path and equivalent radius of the drop size distribution. The cloud radiative properties are then obtained from standard two-stream equations for a homogeneous layer. The effect of water vapor absorption within the cloud is ignored in this version, leading to a small underestimate of the cloud absorption. The parameterization is compared with other schemes and with aircraft observations. It performs satisfactorily even when only four spectral bands are employed. The explicit separation of the dependence of the derived cloud radiative properties of the liquid water path and equivalent radius is new, and should prove valuable for climate change investigations. -from Author"
"7202208382;57203400519;6603565405;6507777841;","Interactions among radiation, convection, and large-scale dynamics in a general circulation model",1989,"10.1175/1520-0469(1989)046<1943:IARCAL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024830046&doi=10.1175%2f1520-0469%281989%29046%3c1943%3aIARCAL%3e2.0.CO%3b2&partnerID=40&md5=dcf3cdd2ebac58614bbd29eac117185c","We have analyzed the effects of radiatively active clouds on the climate simulated by the UCLA/GLA GCM, with particular attention to the effects of the upper tropospheric stratiform clouds associated with deep cumulus convection, and the interactions of these clouds with convection and the large-scale circulation. Taken together, our results show that upper tropospheric clouds associated with moist convection, whose importance has recently been emphasized in observational studies, play a very complex and powerful role in determining the model results. -from Authors"
"7004288767;6602685484;","Cloud chemistry research at Whiteface Mountain",1989,"10.1111/j.1600-0889.1989.tb00127.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024567268&doi=10.1111%2fj.1600-0889.1989.tb00127.x&partnerID=40&md5=5b115038cbf1015ff6e0d39c1742db70","Cloud collection principles are briefly reviewed; the performance of two collectors in common use is compared. Two cloud event studies (one during winter, the other during summer) are presented to contrast typical time‐dependent histories of chemical concentrations for the two seasons. During winter, the oxidation rate of SO2 is low, resulting in measured sulfate concentrations independent of SO2 concentrations. During summer, SO2 is rapidly oxidized by H2O2 with a residue of H2O2 persisting in cloud water after SO2 has been converted. Changes in the gas phase concentrations of SO2 and H2O2 are shown during a cloud event. Both gases drop to very low concentrations in cloud with H2O2 tending to recover after available SO2 has been oxidized. The meteorology for each event is presented to illustrate the role of atmospheric structure in the transporting of emitted material and in determining cloud water compositions. Finally, a cloud chemistry climatology for winter and summer is presented, based upon 6 years of observations at Whiteface Mountain. 1989 Blackwell Munksgaard"
"7005311892;16637291100;7202840464;","Merging AVHRR and SMMR data for remote sensing of ice and cloud in polar regions",1989,"10.1080/01431168908904000","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024856077&doi=10.1080%2f01431168908904000&partnerID=40&md5=dfe9c80db0b8ad29ba990ade2c5a5d9c","Multispectral data from the Advanced Very High Resolution Radiometer (AVHRR) were digitally processed and merged with Scanning Multichannel Microwave Radiometer (SMMR) imagery. Five channels of AVHRR data, four channels of SMMR brightness temperatures and SMMR-derived ice concentration and ice type were co-registered to a polar stereographic grid. The merged data sets are currently being used in combination with meteorological information for integrated studies of clouds and sea ice. © 1989 Taylor & Francis Ltd."
"7103245074;7202840464;","Evaluation of algorithms for mapping snow cover parameters in the Federal Republic of Germany using passive microwave data",1989,"10.3112/erdkunde.1989.02.02","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024785062&doi=10.3112%2ferdkunde.1989.02.02&partnerID=40&md5=04b498ad194540611f6208d99ea9949f","Passive microwave techniques are capable of producing snow extent data sets for synoptic scale climate research in mid-latitude areas. Their ease of application in an automated fashion and the capability of mapping snow extent in the presence of persistent cloud cover constitutes the superiority of passive microwave techniques over current operational snow mapping procedures using visible band imagery, despite the greater accuracy of visible band techniques in the absence of cloud cover. -from Authors"
"35446498700;6508151792;57191357166;6603968676;7006852452;7202485447;","Monitoring the chemical climate of the Mt. Mitchell State Park for evaluation of its impact on forest decline",1989,"10.3402/tellusb.v41i1.15054","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024483273&doi=10.3402%2ftellusb.v41i1.15054&partnerID=40&md5=fab93458ceca11b3f182af4616b19464","We erected a 16.5m tall aluminium walk-up tower and instrumented it with an electronic weather station, cloud water collectors and ozone analyzers. Our observations during summer 1986 confirm that Mt. Mitchell has a high frequency of being immersed in clouds. Although the average pH of precipitation was about 4.4 the pH of cloud water ranged between 2.2-5.4. The pH of the cloud water was demonstrated to be a function of wind direction at the site. During early summer episodes, neutralization of the acidic anions (SO4= and NO3-) was not as effective as in the later summer episodes. During all cloud episodes, ozone concentration registered a dramatic decrease. The average minimum ozone concentration of about 63 ppb during the whole summer of 1986 was above the backgound level (50 ppb) in the United States. Diurnal ozone variation revealed a nocturnal maximum of about 75 ppb after sunset. This is contrary to conventional midday maximum in ozone concentration reported in the literature. Episodic excursions in ozone concentration equal to or exceeding 100 ppb level were found on 5 occasions. The maximum cloud water deposition rate, which is estimated using a micrometeorological model, is found to be 1.30 mm h-1. Ionic deposition due to direct cloud capture is found to be 2 to 5 times the deposition due to precipitation, and the evaporation associated with wind speeds as high as 15-18m s-1 realized during some episodes is pointed out to be of great significance regarding the canopy exposure. -from Authors"
"7005533663;7004201998;","Diagnosis of cloud amount increase from an analogue model of a warming world",1989,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024812789&partnerID=40&md5=fc18ba992611befe2859d66b7b4c7145","Using cloud amount records for the continental USA (published), Canada, including parts of the Arctic (in preparation), Europe (published) and the Indian sub-continent (new results), cloudiness changes have been analyzed in the context of the analogue model which compares records of two contrasting 20 yr periods. Cloud amount is found to increase over practically the entire USA, Canada, most of the Indian subcontinent, and parts of Europe in all seasons. These results have been derived for a wide range of climates and considerably strengthen the view that total cloud amount increases in a warming world. It must be recognized that the historical record reviewed here is land-based only, contained within the Northern Hemisphere and excludes many more areas especially the tropics and equatorial regions. -from Authors"
"7005533663;","North American total cloud amount variations this century",1989,"10.1016/0031-0182(89)90176-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024813928&doi=10.1016%2f0031-0182%2889%2990176-4&partnerID=40&md5=e7623890e91751e2aa32532838e6a075","Records of mean monthly total cloud amount from 143 locations in North America have been assembled. Generally the low and middle latitude station records extend over the period 1900-1984 (U.S.A.) and 1900-1982 (Canada) but few Arctic stations have records before 1930 and some begin recording cloud amount as late as the 1960s. The low and middle latitude station records show a tendency for total cloud amount to increase over this century. Only one of the 77 continental U.S.A. stations does not show an increase. The high latitude stations record increasing total cloud amount in the summer (June, July, August) season but not in the annual mean. The records show the largest increase between about 1930 and 1950. They are temporally consistent but do not exhibit significant spatial coherence. The history of observing and reporting practice has been carefully examined; if any significant effect were to be expected from the changes documented it would be a decrease at the time when the greatest recorded increase occurs. Other factors associated with increased population are possible ""explanations"". The most likely cause of increased cloud amount (if the temporal trend is real) is anthropogenerated clouds in the form of jet aircraft condensation trails but the large (1930-1950) increase identified here pre-dates the introduction of widespread commercial airflights even in the U.S.A. © 1989."
"35446498700;6508151792;57191357166;57191353564;7006852452;7202485447;","Monitoring the chemical climate of the Mt. Mitchell State Park for evaluation of its impact on forest decline",1989,"10.1111/j.1600-0889.1989.tb00128.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989052699&doi=10.1111%2fj.1600-0889.1989.tb00128.x&partnerID=40&md5=02b48dd437824db95f729ef5f7736550","During the last decade, a new type of forest decline has become increasingly apparent, especially at high elevations, in north America and western Europe. One of the causes for this decline could be anthropogenic air pollutants, the deposition of which is facilitated by natural causes at high elevations such as strong windfield, direct cloud capture by the forest canopy, high frequency of frosting and riming etc. At Mt. Mitchell, North Carolina (35°44′05″N, 82°17′15″W) which is the highest peak (2,038 m MSL) in the eastern United States, the decline of red spruce and Fraser fir forest is noticeable above the cloud‐base which is frequently observed around 1585 m MSL. In order to quantitatively assess the chemical climate of Mt. Mitchell State Park, we erected a 16.5 m tall aluminium walk‐up tower and instrumented it with an electronic weather station, cloud water collectors and ozone analyzers. Our observations during summer 1986 confirm that Mt. Mitchell has a high frequency of being immersed in clouds. During early morning hours, cloudiness is maximum in frequency and results in short duration cloud events ranging from 2‐8 h. Although the average pH of precipitation was about 4.4, the pH of cloud water ranged between 2.2–5.4. Short‐duration cloud events (8 h or less) were more acidic, in general, than the long duration ones during which the cloud water was most acidic at the onset and dissipative stages. Both types of event were characterized by highly variable liquid water content (LWC) which was lower for the short events. The pH of the cloud water was demonstrated to be a function of wind direction at the site. For the average wind direction of 210°, the pH was 3.4. During early summer episodes, neutralization of the acidic anions (SO−−4 and NO−3) was not as effective as in the later summer episodes. During all cloud episodes, ozone concentration registered a dramatic decrease. The average minimum ozone concentration of about 63 ppb during the whole summer of 1986 was above the background level (50 ppb) in the United States. Diurnal ozone variation revealed a nocturnal maximum of about 75 ppb after sunset. This is contrary to conventional midday maximum in ozone concentration reported in the literature. Episodic excursions in ozone concentration equal to or exceeding 100 ppb level were found on 5 occasions. The maximum cloud water deposition rate, which is estimated using a micrometeorological model, is found to be 1.30 mm h−1. Ionic deposition on the forest canopy is found to be similar to that reported for the Mt. Moosilauke (New Hampshire) forest. Ionic deposition due to direct cloud capture is found to be 2 to 5 times the deposition due to precipitation, and the evaporation associated with wind speeds as high as 15‐18 m s−1 realized during some episodes is pointed out to be of great significance regarding the canopy exposure. 1989 Blackwell Munksgaard"
"7005736664;7005533663;","Modelling the ocean climate for the early archaean",1989,"10.1016/0031-0182(89)90177-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024878845&doi=10.1016%2f0031-0182%2889%2990177-6&partnerID=40&md5=343a5630353897f7c5a7996623e3b0df","A solution to the enhanced surface temperature, lowered solar luminosity ""paradox"" of the early Archaean Earth is presented in terms of albedo modifications due to the presence of a near global ocean and fewer clouds. An interlinked suite of three ocean thermodynamic/dynamic models is used to cross-substantiate the viability of an oceanic climate in which zonal transports are enhanced, pole-to-equator transports diminished and surface temperatures are only a few degrees below present day values throughout the year. This provides substantiation for one of the two radiative explanations for the ""remarkable"" stability of the Earth's surface temperature for the whole of the geological record. Although an ""alternative"" (for the ocean-dominated Archaean Earth) to the previously well-discussed ""radiation-trapping by greenhouse gases"" mechanism, it is likely that both mechanisms operated during the early phases of the Earth's history. © 1989."
"7102331727;57203209031;7402362998;","Characterization of combustion aerosols for haze and cloud formation",1989,"10.1080/02786828908959222","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024610355&doi=10.1080%2f02786828908959222&partnerID=40&md5=740c088f13ae75eccf0c79d66312d5a0","Aerosols resulting from the combustion of acetylene, wood, and JP-4 aviation fuels have been characterized in both the laboratory and the larger field scales by activity as cloud condensation nuclei (CCN), the total particle or condensation nuclei (CN) count, ion chromatography (IC) on filter samples, and morphology by scanning electron microscopy. The CCN/CN ratio for a given aerosol sample is a quantitative indicator of the ability of a combustion aerosol to become involved in atmospheric removal by nucleation scavenging. On both the laboratory and the field scales, this ratio was in the range 0.2-1.0 for the wood combustion aerosol, 0.2-0.5 for the acetylene case, and only 0.01-0.03 for JP-4. The CCN/CN ratios are identical for both the field and laboratory studies, implying that laboratory studies of CCN activities can be justifiably extrapolated to field studies. Aging and size-classified nucleation studies are also reported. © 1989 Elsevier Science Publishing Co., Inc."
"6506755902;","Solar system and galactic influences on the stability of the earth",1989,"10.1016/0031-0182(89)90182-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024486383&doi=10.1016%2f0031-0182%2889%2990182-X&partnerID=40&md5=0fa096a0ca4696a3e616e0c7767f3753","In addition to the intrinsic variability of the solar output, there exist a variety of ways in which the stability of the Earth's environment can be affected by the cosmos. The change with time of the shape and orientation of the Earth's orbit and precession of the rotational axis of the Earth caused by the gravitational forces from other members of the Solar System induce predictable variations in the terrestrial climate which can be seen in the geologic record. Encounters of the Solar System with dense interstellar gas clouds can also exert considerable influences on the terrestrial environment as can the occasional nearby explosion of supernovae. However, the most dramatic and, perhaps, the most likely hazards presented to the Earth by the cosmos are from the occasional collisions with substantial asteroids or comets. The energy delivered to the Earth in such an event would be equivalent to 10,000 times the total nuclear weapons stockpile of all nations. Such an event would have, and is thought to have had, enormous consequences for the stability of the biosphere. © 1989."
"7003935733;","NOAA Satellite programs in support of a global change program",1989,"10.1016/0273-1177(89)90176-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45249125333&doi=10.1016%2f0273-1177%2889%2990176-2&partnerID=40&md5=f2f6d7a3d59f0ddf98a2fc80aa10d49e","Although designed primarily for weather observations, NOAA's operational polar satellites have the potential to provide considerable information on global change. The weather/climate products routinely produced from these satellites and relevant to global change are discussed. They include: ocean surface temperatures, snow cover area for Europe and Eurasia, Arctic and Antarctic sea ice area, global vegetation index, narrow-band estimates of the Earth's radiation budget, atmospheric ozone, and stratospheric temperatures. Global and hemispheric time series of these variables as determined from satellites are presented. Algorithms for new products--aerosol optical depth, surface radiation budget, land surface temperature, cloud amounts and heights, precipitation, and cloud liquid water--are being developed. NOAA's plans for the NOAA K,L,M satellite series and the Polar Platform are discussed. © 1989."
"7006099992;","Potential future applications of ocean colour sensing for large scale and global studies",1989,"10.1016/0273-1177(89)90142-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45249127443&doi=10.1016%2f0273-1177%2889%2990142-7&partnerID=40&md5=39cb5b7b43b1ccecf5666cbd38f495fe","Mapping of ocean colour, although often interrupted by clouds, provides the only quantitative indication of ocean biological production from space. Compared to other areas of remote sensing, the work is in an early stage of development, since only the first prototype sensor (the CZCS) has been flown on a satellite. Improved optical sensing techniques have been tested in aircraft, and suggest that important improvements are possible. Ocean optical sensing is at present in limbo, and must rely on sensors designed for land or clouds. However, good colour information is urgently needed for global environment and climate studies. In this paper, current international plans for the Joint Global Ocean Flux Study (JGOFS), and its requirements for satellite data, are briefly reviewed. An example is presented of an improved passive optical sensing technique that may become available from future satellites. © 1989."
"7005736664;7005533663;","Modelling the ocean climate for the early archaean",1989,"10.1016/0921-8181(89)90003-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45349111336&doi=10.1016%2f0921-8181%2889%2990003-9&partnerID=40&md5=760507142d32e4d9d7a833d64e6bcb27","A solution to the enhanced surface temperature, lowered solar luminosity ""paradox"" of the early Archaean Earth is presented in terms of albedo modifications due to the presence of a near global ocean and fewer clouds. An interlinked suite of three ocean thermodynamic/dynamic models is used to cross-substantiate the viability of an oceanic climate in which zonal transports are enhanced, pole-to-equator transports diminished and surface temperatures are only a few degrees below present day values throughout the year. This provides substantiation for one of the two radiative explanations for the ""remarkable"" stability of the Earth's surface temperature for the whole of the geological record. Although an ""alternative"" (for the ocean-dominated Archaean Earth) to the previously well-discussed ""radiation-trapping by greenhouse gases"" mechanism, it is likely that both mechanisms operated during the early phases of the Earth's history. © 1989."
"7005228425;","Fine particles in the global troposphere A review",1989,"10.1111/j.1600-0889.1989.tb00132.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024568293&doi=10.1111%2fj.1600-0889.1989.tb00132.x&partnerID=40&md5=194cb31e9c102188373ba209a321a54e","The available body of data on fine particles (> 1 μm radius) in the troposphere is reviewed in relation to our understanding of sources, sinks and transformation processes of atmospheric aerosols. This review yields the following results. There are no data available to characterize the free troposphere above the boundary layer. Most of the boundary layer data suffer from the lack of a well‐defined upper size limit of the samplers at about 1 μm radius and concurrent results on total fine particle mass. The fine particle composition data are consistent with our understanding of natural and anthropogenic sources of trace substances, which lead to fine particles. The chemical composition is presented for the three aerosol types: urban, non‐urban continental and remote regions. Special attention needs to be focused on fine particle interaction with clouds for three reasons. Fine particles control number‐ and surface‐distribution of the condensed matter; the state of precondensation haze and clouds provide the most important processes of fine particle elimination from the atmosphere. Furthermore, climatic effects of fine particles as expressed by their interaction with atmospheric radiation is strongest during their passage through clouds. Very little is known about the processing of aerosols through clouds. Consequently, there are large uncertainties about their climatic effect and their lifetime in the atmosphere. Finally, no single type of secular trend in particle concentration is found on a global scale. Depending on which component and which geographical region is monitored, both decreasing and increasing concentrations have been measured. The differences are consistent with our understanding of aerosol properties and their gas phase precursors. 1989 Blackwell Munksgaard"
"55664272500;","An energy balance climate model study of radiative forcing and temperature response at 18 ka",1989,"10.1029/jd094id10p12873","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024880701&doi=10.1029%2fjd094id10p12873&partnerID=40&md5=c442d8e8791ad818f05bebbef974db18","Imposition of CLIMAP sea and land ice and CLIMAP sea surface temperatures (SSTs) gives a global mean atmospheric cooling of 3.4°C, while imposition of land glacier ice alone with freely predicted SSTs, sea ice, and seasonal land snow cover causes global mean cooling of 3.2°C, northern hemisphere sea ice extent close to the CLIMAP amounts, but relatively little response in the southern hemisphere. Reducing atmospheric CO2 from 280 to 200 parts per million by volume (ppmv), applying the base case LGM aerosol increase scenario of L.D.D. Harvey (1988a), or decreasing the effective cloud droplet radius over oceans by 4% with constant liquid water content (LWC), as suggested by data from polar ice cores, gives global mean atmosheric coolings of 1.5°C, 2.2°C, and 0.9°C, respectively. -from Author"
"6603362623;","Numerical simulation of coastal flows when solar radiation is blocked by smoke",1989,"10.1175/1520-0450(1989)028<0361:NSOCFW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024472356&doi=10.1175%2f1520-0450%281989%29028%3c0361%3aNSOCFW%3e2.0.CO%3b2&partnerID=40&md5=8ab82c2edfe4ac61ffd996026987dbbf","Smoke from fires ignited in a large-scale nuclear exchange would greatly reduce the flux of solar radiation at the ground and lead to rapid cooling over continental regions. Because of its large heat capacity, the ocean would cool more slowly so that a thermal gradient would tend to develop at the continental coastlines. In order to investigate the hypothesis that these thermal gradients would lead to zones of persistent precipitation along the coastlines, a modified version of the Colorado State University Mesoscale Model has been used to simulate the evolution of atmospheric flows for both West and East coasts assuming a moderate westerly synoptic flow of 5 m s-1. In both cases a layer of fog forms over the ground, effectively limiting the rate of cooling over land. This fog layer grows in height as the atmosphere aloft cools, forming a stratus cloud. Moisture from the ocean surface, mixed vertically into a radiatively cooled atmosphere, causes a cloud layer to form over the ocean as well. With both land and sea covered by clouds, there is no differential cooling, anomalous flow fields, or enhanced precipitation. These simulations also demonstrate the important role of moisture in moderating the initial rate of atmospheric cooling when solar radiation is blocked by smoke."
"9235685300;","Role of absorbed solar radiation on Indian Ocean surface temperature: A case study for calm winds using satellite data",1989,"10.1016/0034-4257(89)90052-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024856755&doi=10.1016%2f0034-4257%2889%2990052-7&partnerID=40&md5=4e874ef57dc253e6e5aa68bf73be2950","Knowledge of sea surface temperature (SST) changes has been recognized to be an important component of climate prediction models. SST variations are mainly controlled by the solar heat input, the ocean mixed layer processes, and the wind speed at the ocean surface. In this paper an attempt has been made to study the effect of absorbed solar radiation at the ocean surface on SST variations in the Indian Ocean region using MONEX-79 data as a case study. Mixed layer depth (MLD) is estimated by the gradient method using Russian ships' temperature profiles. Absorbed solar radiation at the ocean surface has been estimated from the cloud amount and the planetary value of the absorbed solar radiation obtained from the TIROS-N operational products. In the month of May 1979, the changes in MLD and the wind speed were minimal and thus the effects of MLD and wind speed variations on SST were not statistically significant. A regression of SST on absorbed solar radiation at the ocean surface is fitted. It is observed that the day-to-day changes in SST are in phase with those in absorbed solar radiation in the month of May 1979. This is not true for the months of June and July 1979 because of the prominent changes in MLD and wind speed in these months. It could be thus concluded that in order to understand and predict SST changes, the variations in the absorbed solar radiation are an important input to be monitored. © 1989."
"7203015939;","Ocean to atmosphere carbon monoxide flux: Global inventory and climate implications",1989,"10.1029/GB003i004p00305","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024870075&doi=10.1029%2fGB003i004p00305&partnerID=40&md5=2b17b666ab9c6a94a49411c6aade1a3e","The global ocean to atmosphere flux of carbon monoxide (CO) is simulated with 4.5° × 7.5° latitude‐longitude spatial resolution using global data fields derived from an atmospheric general circulation model. The cloud and radiation package in the National Center for Atmospheric Research Community Climate Model is used to estimate the solar energy at the Earth's surface. This quantity is empirically related to photochemical interaction with dissolved organic matter, and the global concentration field of CO in surface seawater is estimated. Areas associated with the Intertropical Convergence Zone and mid‐ to high‐latitude winter hemisphere regions have relatively low climatological CO surface ocean concentrations on a local scale. The global surface wind and temperature fields are simultaneously used to calculate the global transfer velocity field of CO. Coupling these two computed fields, a global ocean to atmosphere CO flux of 165± 80 Tg yr−1 is proposed. The CO flux rates vary globally from 0.1 to 12 ug cm−2 month−1. The fluxes are largest in the mid‐latitude summer hemispheres, with a maximum at 40° S during the austral summer that is 40% larger on a zonal average than at any northern hemisphere latitude. Relatively small continental sources of CO to the southern hemisphere atmosphere and the short atmospheric residence time of this trace gas indicate that ocean‐derived CO may influence the local photochemical dynamics in the remote marine boundary layer of this region. A possible climate feedback scenario involving UV radiation, ozone, OH, and the air‐sea exchange of CO is proposed. The global ocean to atmosphere CO flux proposed here is at the high end of those used in previous atmospheric CO budgets. This estimate however must be considered a lower limit because no explicit simulation of global oceanic primary productivity is presently in the model. Copyright 1989 by the American Geophysical Union."
"7006894478;","Changing patterns in dust filtration research.",1989,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024537901&partnerID=40&md5=e40cb597179f601138ad9321f888cb09","Early studies of dust filtration arose from the need to understand the action of fibrous filters challenged by smokes developed for chemical warfare. Concepts of depth filtration have subsequently been translated, by way of napped woven cloths into needlefelts used in pulse jet filters. Modern surface finished felts, used commercially, promote true dust cake formation although the distinction between depth filtration and cake filtration is not always recognized. The performance of practical dust filters cannot be predicted from such academic studies due to by-products of cake release mechanisms. Future areas for research were found in the action of pulse jets, efficiency of cake release and partial recollection of the discharged dust cake. In this connection the penetration and percolation of needlefelt by a dust cloud becomes important and we must return to considering mechanisms of depth filtration. In conclusion some comments are made on the changing pattern of the climate for future academic researches."
"7003601758;","Towards a surface radiation climatology: Retrieval of downward irradiances from satellites",1989,"10.1016/0169-8095(89)90023-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024926872&doi=10.1016%2f0169-8095%2889%2990023-9&partnerID=40&md5=91e92eed05646de266e413af7d31d3d4","Methods are reviewed for retrieving the downward shortwave (0.3-4 μm) and longwave (4-100 μm) irradiances at the earth's surface from satellites. Emphasis is placed on elucidating the physical aspects relevant to the satellite retrieval. For the shortwave irradiance an example of a retrieval is presented. The shortwave retrieval is facilitated by a close linear coupling between the reflected radiance field at the top of the atmosphere and the surface irradiance. A linear relationship between planetary albedo and surface irradiance does also account properly for cloud absorption, since cloud absorption and albedo are linearly related. In the longwave the retrieval is more difficult since only atmospheric window radiances at the top of the atmosphere can bear information on the near-surface radiation field. For the remainder of the longwave spectrum the radiation regimes at the top of the atmosphere and at the surface are decoupled. More than 80% of the clear-sky longwave flux reaching the surface is emitted within the lowest 500 m of the atmosphere. In cloudy conditions the radiation fields at the surface and at the top of the atmosphere are entirely decoupled. Cloud contributions to the surface irradiance are important within the atmospheric window (8-13 μm) and the relative contribution increases in drier climates. Summaries are presented of various techniques devised for both the solar and longwave surface irradiances. A compilation of reported standard errors of shortwave techniques in comparison with ground measurements yields median values of about 5% and 10% for monthly and daily mean values, respectively. Standard errors for the longwave are of the order of 10-25 W m-2. Reported biases are typically of the order of 5 W m-2. For the shortwave retrieval there are fairly good prospects to obtain monthly mean estimates with the requested accuracy of about 10 W m-2 over regional scale areas. The inherent problems of the longwave still entails improvements. The requested retrieval accuracy may be reached with advanced techniques for estimating cloud base height and with the exploitation of correlative data, such as the analysis for numerical weather prediction of fields of temperature and humidity. The use of such data should also be advantageous to physical methods for the shortwave retrieval. Validation studies are compromised by the different nature of single spot surface measurements and area covering satellite retrievals. For physical retrievals employing radiative transfer codes it is recommended to test models against a defined standard. © 1989."
"6506755902;","Solar system and galactic influences on the stability of the earth",1989,"10.1016/0921-8181(89)90014-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45249127262&doi=10.1016%2f0921-8181%2889%2990014-3&partnerID=40&md5=99bce5cae245bc153d07fdddaad68c05","In addition to the intrinsic variability of the solar output, there exist a variety of ways in which the stability of the Earth's environment can be affected by the cosmos. The change with time of the shape and orientation of the Earth's orbit and precession of the rotational axis of the Earth caused by the gravitational forces from other members of the Solar System induce predictable variations in the terrestrial climate which can be seen in the geologic record. Encounters of the Solar System with dense interstellar gas clouds can also exert considerable influences on the terrestrial environment as can the occasional nearby explosion of supernovae. However, the most dramatic and, perhaps, the most likely hazards presented to the Earth by the cosmos are from the occasional collisions with substantial asteroids or comets. The energy delivered to the Earth in such an event would be equivalent to 10,000 times the total nuclear weapons stockpile of all nations. Such an event would have, and is thought to have had, enormous consequences for the stability of the biosphere. © 1989."
"7006894478;","Changing patterns in dust filtration research",1989,"10.1016/S0015-1882(89)80055-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024303360&doi=10.1016%2fS0015-1882%2889%2980055-2&partnerID=40&md5=321439395b0674420a0b483c1e29c58b","Early studies of dust filtration arose from the need to understand the action of fibrous filters challenged by smokes developed for chemical warfare. Concepts of depth filtration have subsequently been translated, via napped woven cloths into needlefelts used in pulse-jet filters. Modern surface-finished felts, used commercially, promote true dust cake formation although the distinction between depth filtration and cake filtration is not always recognised. The performance of practical dust filters cannot be predicted from such academic studies due to by-products of cake release mechanisms. Future areas for research will be found in the action of pulse-jets, efficiency of cake release and partial re-collection of the discharged dust cake. In this connection the penetration and percolation of needlefelt by a dust cloud becomes important and we must return to considering mechanisms of depth filtration. In conclusion some comments are made on the changing pattern of the climate for future academic researches. © 1989, Uplands Press Ltd.. All rights reserved."
"7004158760;","Topoclimatic controls in an alpine fellfield and their ecological significance",1989,"10.1080/02723646.1989.10642364","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024837569&doi=10.1080%2f02723646.1989.10642364&partnerID=40&md5=e0949c9dc96ef2baa4ff3bf40d9b2c35","The interaction of topography and ambient atmospheric conditions and their combined effect on surface climate are studied in the alpine fellfield on Niwot Ridge, Colorado Front Range. Insolation, net shortwave and all-wave radiation, surface and air temperatures, ground heat flux, wind speed, and evapotranspiration are analyzed in order to characterize moisture and energy exchanges. The spatial pattern of daily energy and moisture fluxes is influenced more by cloud cover than topographic position. The daily radiation load is usually highest on east-facing slopes because clear mornings are commonly followed by cumulus development during midday and early afternoon. In the dominant westerly wind regime, wind speeds on east-facing slopes are lower than elsewhere. Strong insolation produces high rates of evapotranspiration from the thin, sandy/gravelly fellfield soil when moisture is abundant. After a few consecutive precipitation-free days, large radiation loads produce high surface temperatures, especially on east-facing slopes where wind speed and thus the sensible heat flux are small. During the 1985 summer drought period, the impact of hot, dry weather on plant water stress was most pronounced on east-facing slopes. The well-defined distribution of Dryas octopetala on Niwot Ridge, near the southern extent of its circumpolar range, is an example of the control of topoclimate over plant distribution owing to water stress during periods of drought The absence of Dryas from south-facing slopes does not correspond well with present topoclimatic patterns. The present distribution of Dryas may be a consequence of topoclimatic patterns throughout the middle of the last millennium when the summer climate in the Colorado Front Range was hotter and drier than today. Summer droughts then were probably more prolonged, and a combination of clearer days, lower wind speeds, or an increased frequency of northerly wind would have created more intense water stress on south-facing than east-facing slopes. © 1989 Taylor & Francis Group, LLC."
"7005775438;6602207339;","The Greenhouse effect: Impacts of ultraviolet-B (UV-B) radiation, carbon dioxide (CO2), and ozone (O3) on vegetation",1989,"10.1016/0269-7491(89)90166-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024475661&doi=10.1016%2f0269-7491%2889%2990166-8&partnerID=40&md5=a7c3370e72035e41c9422c5757ea0896","There is a fast growing and an extremely serious internaitonal scientific, public and political concern regarding man's influence on the global climate. The decrease in stratospheric ozone (O3) and the consequent possible increase in ultraviolet-B (UV-B) is a critical issue. In addition, tropospheric concentrations of 'greenhouse gases' such as carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) are increasing. These phenomena, coupled with man's use of chlorofluorocarbons (CFCs), chlorocarbons (CCs), and organo-bromines (OBs) are considered to result in the modification of the earth's O3 column and altered interactions between the stratosphere and the troposphere. A result of such interactions could be the global warming. As opposed to these processes, tropospheric O3 concentrations appear to be increasing in some parts of the world (e.g. North America). Such tropospheric increases in O3 and particulate matter may offset any predicted increases in UV-B at those locations. Presently most general circulation models (GCMs) used to predict climate change are one- or two-dimensional models. Application of satisfactory three-dimensional models is limited by the available computer power. Recent studies on radiative cloud forcing show that clouds may have an excess cooling effect to compensate for a doubling of global CO2 concentrations. There is a great deal of geographic patchiness or variability in climate. Use of global level average values fails to account for this variability. For example, in North America: 1. 1. there may be a decrease in the stratospheric O3 column (1-3%); however, there appears to be an increase in tropospheric O3 concentrations (1-2%/year) to compensate up to 20-30% loss in the total O3 column; 2. 2. there appears to be an increase in tropospheric CO2, N2O and CH4 at the rate of roughly 0·8%, 0·3% and 1-2%, respectively, per year; 3. 3. there is a decrease in erythemal UV-B; and 4. 4. there is a cooling of tropospheric air temperature due to radiative cloud forcing. The effects of UV-B, CO2 and O3 on plants have been studied under growth chamber, greenhouse and field conditions. Few studies, if any, have examined the joint effects of more than one variable on plant response. There are methodological problems associated with many of these experiments. Thus, while results obtained from these studies can assist in our understanding, they must be viewed with caution in the context of the real world and predictions into the future. Biomass responses of plants to enhanced UV-B can be negative (adverse effect); positive (stimulatory effect) or no effect (tolerant). Sensitivity rankings have been developed for both crop and tree species. However, such rankings for UV-B do not consider dose-reponse curves. There are inconsistencies between the results obtained under controlled conditions versus field observations. Some of these inconsistencies appear due to the differences in responses between cultivars and varieties of a given plant species; and differences in the experimental methodology and protocol used. Nevertheless, based on the available literature, listings of sensitive crop and native plant species to UV-B are provided. Historically, plant biologists have studied the effects of CO2 on plants for many decades. Experiments have been performed under growth chamber, greenhouse and field conditions. Evidence is presented for various plant species in the form of relative yield increases due to CO2 enrichment. Sensitivity rankings (biomas repsonse) are agein provided for crops and native plant species. However, most publications on the numerical analysis of cause-effect relationships do not consider sensitivity analysis of the mode used. Ozone is considered to be the most phytotoxic regional scale air pollutant. In the pre-occupation of loss in the O3 column, any increases in tropospheric O3 concentrations may be undermined relative to vegetation effects. As with the other stress factors, the effects of O3 have been studied both under controlled and field conditions. The numerical explanation of cause-effect relationships of O3 is a much debated subject at the present time. Much of the controversy is directed toward the definition of the highly stochastic, O3 exposure dynamics in time and space. Nevertheless, sensitivity rankings (biomass response) are provided for crops and native vegetation. The joint effects of UV-B, CO2 and O3 are poorly understood. Based on the literature of plant response to individual stress factors and chemical and physical climatology of North America, we conclude that nine different crops may be sensitive to the joint effects: three grain and six vegetable crops (sorghum, oat, rice, pea, bean, potato, lettuce, cucumber and tomato). In North America, we consider Ponderosa and loblolly pines as vulnerable among tree species. This conclusion should be moderated by the fact that there are few, if any, data on hardwood species. In conclusion there is much concern for global climate change and its possible effects on vegetation. While this is necessary, such a concern and any predictions must be tempered by the lack of sufficient knowledge. Experiments must be designed on an integrated and realistic basis to answer the question more definitively. This would requrie very close co-operation and communication among scientists from multiple disciplines. Decision makers must realize this need. © 1989."
"6603672620;6603885684;7103270522;24390052400;","The establishment of vegetation after late pleistocene deglaciation in the Paramo de Miranda, Venezuelan Andes",1988,"10.1016/0034-6667(88)90052-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024220789&doi=10.1016%2f0034-6667%2888%2990052-8&partnerID=40&md5=0c5cd62e70577c0ced09c19ab670f1c0","Palynological analyses of samples from a fluvioglacial terrace at 3920 m elevation, in the periglacial belt of the Paramo de Miranda, has shown that, before 11,500 to about 11,120 yr B.P., the very few plants growing in the region belonged to the Gramineae, the Compositae (mainly to Coespeletia) and Montia. The climate was colder than at present. During the early Holocene the concentration of pollen and spores in sediments increased and new pollen types from paramo plants were incorporated. Pollen of the Caryophyllaceae (mainly Arenaria), of Gentiana, Valeriana, Geranium and a few genera of Compositae reached the site. Long-distance pollen, derived from the cloud forest increased and Podocarpus pollen was more abundant than at present. These results suggest that temperatures increased at the beginning of the Holocene, the vegetation attaining a density similar to that of the present, although with fewer species. From 5470 to 2500 yr B.P. pollen and spore concentrations fluctuated and other types, including Rhizocephalum and Isoetes, followed by Draba, Plantago and certain other genera of the Composite were now present in the sediments. From ca 3000 yr B.P. onwards the composition of the pollen assemblages was the same as at present. Two cold phases were detected, one from earlier than 11,500 to 11,120 yr B.P. and another from 6000 to 5250 yr B.P. A warm phase from ca 2690 to 2500 yr B.P. probably represented a rise of about 1.2°C above the modern average temperature. In general terms, the climatic oscillations detected at Miranda are in accordance with those in other parts of South America. © 1988."
"7005942405;","Toward an improved global network for determination of tropospheric ozone climatology and trends",1988,"10.1007/BF00053861","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023824148&doi=10.1007%2fBF00053861&partnerID=40&md5=8ca5beb9b69037abc01950a067882a86","An examination of typical tropospheric ozone variability on daily, monthly, annual and interannual timescales and instrumental precision indicates that the current ozonesonde network is insufficient to detect a trend in tropospheric ozone of ≤1% per year at the 2σ level even at stations with records a decade in length. From a trend prediction analysis we conclude that in order to detect a 1% per year trend in a decade or less it will be necessary to decrease the time between observations from its present value of 3-7 days to 1 day or less. The spatial distribution of the current ozonesonde stations is also inadequate for determining the global climatology of ozone. We present a quantitative theory taking into account photochemistry, surface deposition, and wind climatology to define the 'effectively sampled region' for an observing station which, used in conjunction with the instrumental precision and the above prediction analysis, forms the basis for defining a suitable global network for determining regional and global ozone climatology and trends. At least a doubling of the present number of stations is necessary, and the oceans, most of Asia, Africa, and South America are areas where more stations are most needed. Differential absorption lidar ozone instruments have the potential for far more frequent measurements of ozone vertical profiles and hence potentially more accurate climatology and trend determinations than feasible with ozonesondes but may produce a (fair weather) biased data set above the cloud base. A strategy for cloudy regions in which either each station utilizes both lidars and sondes or each station is in fact a 'doublet' comprised of a near-sea-level lidar and a proximal-mountain-top lidar could serve to minimize this bias. © 1988 Kluwer Academic Publishers."
"7004189939;35508431200;","Variability of summer cloudiness in the Arctic Basin",1988,"10.1007/BF01029896","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024220837&doi=10.1007%2fBF01029896&partnerID=40&md5=bc8ad37cd08454854e68d08b3068ec3f","The extent and thickness of clouds in the Arctic Basin varied considerably in space and time in the late springs and summers of 1977-1979. While, on the average, clouds covered two thirds or more of the basin at any one time, cloud-free episodes were particularly common from the middle of June to late July and persisted locally for several days or even weeks. The central Arctic was less cloudy than the ocean zones closer to the coast in spring, but more cloudy in summer. Most clouds were semi-transparent, allowing recognition of underlying surface features. Optically thick clouds with middle and high level tops were associated with low pressure systems and with atmospheric flows from lower latitudes at the surface and aloft. Cloud-free skies were most frequent in high pressure cells. Climate models used to assess the impact of CO2 and other trace gases on the radiation budget in the high latitudes should account for the heterogeneity of cloud extent and thickness in the Arctic Basin. © 1988 Springer-Verlag."
"7003979342;","Cloud-radiation feedbacks in a climate model",1988,"10.1016/0169-8095(88)90032-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024193376&doi=10.1016%2f0169-8095%2888%2990032-4&partnerID=40&md5=f0071eb8dff476007fdc1f7b8280689b","Using a global coupled model of the atmosphere, the ocean mixed layer and sea ice, the atmospheric response to a 2% rise of the solar constant is studied with emphasis on cloud feedback processes. Clouds are computed on the basis of the cloud liquid water budget equation including simple parameterizations of cloud microphysics and partial cloud cover. The cloud liquid water content determines the optical properties of the clouds so that cloud optical depth feedbacks can be studied. The change of the cloud cover distribution results in a global and annual mean positive feedback. On the other hand, due to an increase of the cloud liquid water content by approximately 10%, the cloud optical depth feedback is negative at the surface. The atmosphere, however, is heated because of a substantial increase of high cloud infrared opacity, especially in the tropics. Thus, the net cloud feedback is positive for the atmosphere and for the whole planet but negative for the surface. © 1988."
"13406672500;","The radiative and climatic consequences of the changing atmospheric composition of trace gases",1988,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024221660&partnerID=40&md5=e488837d8049bc9e0175e6ae8a99cab3","The predicted global and regional warming is large and should be observable in a statistically significant manner within the next decade or two. The role of the oceans in governing the time-dependence of the predicted changes and the role of cloud-climate interactions in modifying the greenhouse effect are the two largest sources of uncertainty in current theories of climate change. Methane is a potentially significant and complex greenhouse gas since it may amplify the greenhouse effect by: 1) its direct radiative heating; 2) by leading to an increase in troposphere ozone; 3) by increasing stratospheric H2O; and 4) by increasing the probability for formation of clouds in the polar lower stratosphere. -from Author"
"7004201998;7202840464;7103245074;35508431200;57216096747;","Intercomparison of satellite-derived cloud analyses for the Arctic Ocean in spring and summer",1988,"10.1080/01431168808954867","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023823068&doi=10.1080%2f01431168808954867&partnerID=40&md5=89bbb312a0eaded16cc4bf7b38208324","Several methods of deriving Arctic cloud information, primarily from satellite imagery, have been intercompared. The comparisons help in establishing what cloud information is most readily determined in polar regions from satellite data analysis. The analyses for spring-summer conditions show broad agreement, but subjective errors affecting some geographical areas and cloud types are apparent. The results suggest that visible and thermal infrared data may be insufficient for adequate cloud mapping over some Arctic surfaces. © 1988 Taylor & Francis Group, LLC."
"57193132723;7403318365;","Sensitivity of a global climate model to the specification of convective updraft and downdraft mass fluxes",1988,"10.1175/1520-0469(1988)045<2641:SOAGCM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024248827&doi=10.1175%2f1520-0469%281988%29045%3c2641%3aSOAGCM%3e2.0.CO%3b2&partnerID=40&md5=6e70b88513aca2e8fb395e1aedbeb671","A control run with arbitrarily specified updraft mass flux is compared to experiments that predict cumulus mass flux on the basis of low-level convergence, convergence plus surface evaporation, or convergence and evaporation modified by varying boundary layer height. An experiment that includes a simple parameterization of saturated convective-scale downdrafts is also described. Convergence effects on cumulus mass flux significantly improve the model's January climatology by increasing the frequency of occurrence of deep convection in the tropics and decreasing it at high latitudes, shifting the ITCZ from 12°N to 4°S. The experiments have several implications for cloud effects on climate sensitivity. -from Authors"
"7006575453;57203400519;","Temperature dependence of cirrus extinction: implications for climate feedback",1988,"10.1029/jd093id09p11051","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037638998&doi=10.1029%2fjd093id09p11051&partnerID=40&md5=e81c75bc9ec1d3bc359c58d8a0971f55","The measured temperature dependence of infrared absorption in cirrus cloud obtained from previous extensive lidar and radiometer (LIRAD) observations of cirrus is used to investigate the sensitivities of changes in cirrus optical properties to changes in global temperature. The temperature sensitivity of cirrus extinction is found to vary from 0.033oC-1 at -22.5oC to 0.200oC-1 at -72.5oC. Equivalent sensitivities for cirrus optical depth are influenced by observed changes in cirrus cloud depth with temperature and vary from 0.003oC-1 at -22.5oC to 0.241oC-1 at -72.5oC. As high cold cirrus clouds are considered to cause a positive feedback with global temperature change, such a feedback is seen to become particularly strong at the lowest temperatures. -from Authors"
"57207746817;","The effect of cloud parametrization and temperature profile on the climate sensitivity to ozone perturbations",1988,"10.1016/0169-8095(88)90033-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024193375&doi=10.1016%2f0169-8095%2888%2990033-6&partnerID=40&md5=41e685d4bf591fe728c746e0bb65df39","A one-dimensional radiative-convective model extending from 0 to 70 km is used to study the sensitivity of surface temperature to perturbations in the ozone profile. Several simulations have been performed for 03 reductions in various altitude ranges. For each case, the resulting perturbation in the thermal structure is analysed. These calculations have been repeated for several types of cloud layers with different opacities and altitudes. It is shown that the sensitivity of the surface temperature to ozone changes is dependent on the cloudiness assumed. Ozone decreases in the lower atmosphere (0-30 km) cool the surface, since the greenhouse effect is dominant in this region, and the climate sensitivity is enhanced in the presence of a cloud layer. For higher-altitude 03 changes (30-70 km), the sign of the surface temperature variation depends on the cloud characteristics. In fact, the latter result is mostly the consequence of the different equilibrium temperature profiles corresponding to the various types of cloudiness. When high stratospheric ozone is reduced, positive and negative surface temperature changes of several tenths of degree are respectively associated with cold and warm climatic conditions. © 1988."
"7004034323;7003314664;","The response of a general circulation model to cloud longwave radiative forcing. I: Introduction and initial experiments",1988,"10.1002/qj.49711448209","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024197508&doi=10.1002%2fqj.49711448209&partnerID=40&md5=816237097570f278da17f6c4fac9226e","A new version of the NCAR Community Climate Model (CCM1) is used to study the effect of cloud radiative forcing on model simulations. Previous attempts to determine the role played by clouds in climate and the general circulation of the atmosphere are reviewed first. The concept of cloud radiative forcing is discussed and the forcings in the shortwave and longwave spectral regions are contrasted. At low latitudes, the cloud longwave forcing is primarily within the atmosphere, rather than at the surface. It is thus appropriate to study its effect with a model which employs fixed sea surface temperatures (s.s.t.s). The impact of cloud longwave forcing is studied in 510‐day integrations for constant January conditions. The experiments isolate the forcing by tropical and extra‐tropical clouds. Tropical cloud forcing warms the tropical upper troposphere and accelerates the subtropical jets. There are subtle interactions between the forcing, the clear‐sky longwave heating and the latent heating in the tropics. These additional diabatic heating terms oppose the forcing in some regions and enhance it in others. The tropical cloud forcing strengthens the precipitation maxima at low latitudes. There are also changes in the extra‐tropical flow, including the excitation of a pattern in the 200 mb geopotential height differences which is similar to those found in previous studies of the effect of s.s.t. anomalies. This confirms that the forcing may be as important as latent heat release in determining the atmospheric response to such anomalies. The mode is excited with comparable strength by the extra‐tropical cloud forcing. Finally, some concerns regarding the generality of these results and their applicability to other models and the real atmosphere are discussed. These concerns suggest the need for sensitivity studies, some of which are already in progress. Copyright © 1988 Royal Meteorological Society"
"6701652286;7102875645;","Cloud feedback processes in a general circulation model",1988,"10.1175/1520-0469(1988)045<1397:cfpiag>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024221323&doi=10.1175%2f1520-0469%281988%29045%3c1397%3acfpiag%3e2.0.co%3b2&partnerID=40&md5=82d83c11174a68c69fd81800469e3442","The model used is a general circulation model of the atmosphere coupled with a mixed layer model of the oceans. The sensitivity of each version of the model is inferred from the equilibrium response of the model to a doubling of the atmospheric concentration of carbon dioxide. In response to the increase of atmospheric carbon dioxide, cloudiness increases around the tropopause and is reduced in the upper troposphere, thereby raising the height of the cloud layer in the upper troposphere. This implies a reduction of the temperature of the cloud top and, accordingly, of the upward terrestrial radiation from the top of the model atmosphere. On the other hand, the increase of low cloudiness in high latitudes raises the planetary albedo and thus decreases the CO2 induced warming of climate. However, the contribution of this negative feedback process is much smaller than the effect of the positive feedbakc process involving the change of high cloud. -from Authors"
"7403057266;36437371000;","Delayed albedo effects in a zero-dimensional climate model",1988,"10.1175/1520-0469(1988)045<2294:DAEIAZ>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024252919&doi=10.1175%2f1520-0469%281988%29045%3c2294%3aDAEIAZ%3e2.0.CO%3b2&partnerID=40&md5=484467f5b874dab2d8c25905f60dd30d","The parameterization of the albedo in terms of the average global temperature is furthermore not monotonic since it incorporates a ""kink'. This irregularity is assumed to occur for a temperature range wherein the general circulation states of the atmosphere are associated with a high degree of cloud cover, i.e., a large albedo. The fundamental stability properties of the governing delay-differential equation have been resolved using analytical techniques. Numerical investiations have revealed that this simple model does justice to many of the qualitative features generally associated with more complex one-dimensional climate models. Hence it is capable of demonstrating auto-oscillatory behavior as well as a sequence of period-doubling bifurcations towards chaos. -from Authors"
"36893814800;7005533663;","Cloud detection and analysis: A review of recent progress",1988,"10.1016/0169-8095(88)90027-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024193764&doi=10.1016%2f0169-8095%2888%2990027-0&partnerID=40&md5=03f7bc041ca84263e6b1761950a2568c","The major types of cloud retrieval algorithms are reviewed with special emphasis being placed upon recent (i.e., post 1981/1982) developments and novel techniques. Satellite-based retrieval algorithms can be grouped into three classes: threshold methods, statistical procedures, and radiative transfer techniques, although each algorithm depends upon implicit, if not overt, inversion of the radiative transfer equation. The fourth type of retrieval differs very considerably from the satellite-based techniques as it depends upon surface-based measurements which are generally, but not always, human rather than computer based. There is a tendency to assume that surface-based observations, especially of total cloud amount, are ""correct"" but that they may differ from satellite-based retrievals because of the differences in viewing geometry. Actually the literature reveals surprisingly few intercomparison studies. None of the satellite-based techniques have yet been well-validated in a variety of situations, while surface-based observations are made in all terrain and climate regimes. Overall there seems to be good reason to believe that surface-based observations of cloud amount and especially of low cloud amount, character, and base height, can add significantly to satellite-based global nephanalyses now operational or currently being planned. © 1988."
"7102330449;35572014900;","Climatic effect of observed changes in atmospheric trace gases at Antarctica",1988,"10.1016/0004-6981(88)90093-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023821944&doi=10.1016%2f0004-6981%2888%2990093-5&partnerID=40&md5=c1e684263c5fed00bbdd9bbfadcc415a","The seasonal decline in ozone in the Antarctic atmosphere has been termed the 'Antarctic ozone hole'. Possibly this hole is caused by upper atmospheric wind, due to resumption of high solar activity after the polar night which produces large amounts of ozone-destroying nitric oxide or due to unusual chlorine chemistry at extreme cold temperatures and associated polar stratospheric clouds. Of particular concern is that the observed changes in ozone could be linked to the observed increases in the gases that affect ozone such as methane, nitrous oxide, etc. All these gases affect the climate of the Earth through their so-called 'greenhouse' action. We have examined the nature of the greenhouse effect on polar climate due to observed changes in atmospheric trace gases in Antarctica which are reported here. © 1988."
"7006545338;7406650476;","Bulk models of solar radiation at sea",1988,"10.1002/qj.49711447909","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024228227&doi=10.1002%2fqj.49711447909&partnerID=40&md5=45bf22c3422053a2fedbff83b09cb3b3","With a view to improving climate prediction, we test various models for estimating solar radiation at sea from standard meteorological surface observations against long series of radiation measurements at several Ocean Weather Stations and at an offshore island meteorological station. The widely‐used Budyko formula is found to err by up to 32% in estimating long‐term mean insolation, and has even larger errors in reproducing seasonal variations. Various models which estimate solar radiation from solar elevation and from hourly cloud amount and type, using empirical or simple physical formulae, are evaluated. None of these models estimate mean insolation better than an existing formula which relies only on noon solar elevation and daily mean cloud amount, although the hourly models do reproduce seasonal, monthly and daily variations better. None of the formulae using standard surface observations is able to achieve the 10 Wm−2 accuracy in long‐term mean insolation which is required for climate prediction. Copyright © 1988 Royal Meteorological Society"
"6701705994;","On the frequency of precipitation-days in calgary, canada",1988,"10.1111/j.0033-0124.1988.00065.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023716629&doi=10.1111%2fj.0033-0124.1988.00065.x&partnerID=40&md5=28bac86d870980f68f2d944f168140fa","Results of analyses of 86 years of precipitation records for Calgary, Canada, showed that there were three periods of above normal precipitation and three periods of precipitation significantly below normal. This pattern gave the precipitation climate a quasi-periodic appearance. The average number of precipitation-days was 134 per annum. The reduction in the frequency of precipitation-days in dry years was not as significant as the equivalent reduction in precipitation amounts. A significant upward trend in the frequency of precipitation-days, which correlated with a similar trend in cloud cover, was not repeated in precipitation amounts. The upward trend in both cloud cover and precipitation-day frequency is believed to be related to urban growth and the corresponding heat island. This enhancement is more pronounced in the fall and winter months than in the spring and summer. © 1988 by Association of American Geographers."
"7401775859;","Effects of atmosphere on radio imaging for target detection",1988,"10.1029/RS023i005p00731","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024079209&doi=10.1029%2fRS023i005p00731&partnerID=40&md5=edfb04d5d93e6ce978ac8c192dbed1a3","The predictions of atmospheric effects on millimeter wave radio imaging of launch vehicles can be obtained by theoretical extrapolation of measured data from propagation studies for millimeter wave satellite communication systems. Attenuation exceedance statistics versus percentage of time have been estimated for both relatively wet and dry temperate climates. Attenuation problems are minimal at 10 GHz, but increase with frequency. Excessive rain attenuation is expected at 30 GHz for a small fraction of time. Cloud attenuation becomes also significant at 100 GHz. Water vapor in clear air can often cause more than 10 dB attenuation at 300 GHz. By use of the reciprocity theorem the effects of angle‐of‐arrival fluctuations on beam spot resolution have been found to be negligible for a space‐based telescope detecting Earth‐launched vehicles. Beam coverage area averaging can reduce cloud‐induced signal scintillations to less than 1 dB. These statements are valid except at very low elevation angles approaching tangent to the Earth, where the dominant problem is excessive signal attenuation. Copyright 1988 by the American Geophysical Union."
"7006550762;6603364959;7004238859;7006399110;7401548835;","The GISS global climate-middle atmosphere model. Part I: model structure and climatology",1988,"10.1175/1520-0469(1988)045<0329:TGGCMA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024224196&doi=10.1175%2f1520-0469%281988%29045%3c0329%3aTGGCMA%3e2.0.CO%3b2&partnerID=40&md5=de2e97c4ba4072b8482d40fa0bbccee6","The GISS global climate model has been extended to include the middle atmosphere up to an altitude of approximately 85 km. The model has the full array of processes used for climate research, ie numerical solutions of the primitive equations, calculation of radiative and surface fluxes, a complete hydrologic cycle with convective and cloud cover parameterizations etc. In addition, a parameterized gravity wave drag formulation has been incorporated, in which gravity-wave momentum fluxes due to flow over topography, wind shear and convection are calculated at each grid box, using theoretical relationships between the grid-scale variables and expected source strengths. The model produces generally realistic fields of temperature and wind throughout the atmosphere up to approximately 75 km. Important aspects of the current simulation include a proper break between the tropospheric and stratospheric jets, realistic closing off of the wintertime jet in the mesosphere, the observed warm winter/cold summer mesosphere, and a semiannual wind oscillation near the stratopause. The most obvious deficiences are that the long-wave energy itself is somewhat too small in the low and midstratosphere, temperatures are too cold near the model top and are too warm in the polar Southern Hemisphere lower stratosphere during winter. Also, the model generates an inertial oscillation near the equatorial stratopause which may be excessive. -from Authors"
"7006432040;","Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus",1988,"10.1016/0019-1035(88)90116-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024274931&doi=10.1016%2f0019-1035%2888%2990116-9&partnerID=40&md5=0527377b9d461e5cdf828bbba70789d4","A one-dimensional climate model is used to study the response of an Earth-like atmosphere to large increases in solar flux. For fully saturated, cloud-free conditions, the critical solar flux at which a runaway greenhouse occurs, that is, the oceans evaporate entirely, is found to be 1.4 times the present flux at Earth's orbit (S0). This value is close to the flux expected at Venus' orbit early in solar system history. It is nearly independent of the amount of CO2 present in the atmosphere, but is sensitive to the H2O absorption coefficient in the 8- to 12-μm window region. Clouds should tend to depress the surface temperature on a warm, moist planet; thus, Venus may originally have had oceans if its initial water endowment was close to that of Earth. It lost them early in its history, however, because of rapid photodissociation of water vapor followed by escape of hydrogen to space. The critical solar flux above which water is rapidly lost could be as low as 1.1S0. The surface temperature of a runaway greenhouse atmosphere containing a full ocean's worth of water would have been in excess of 1500°K-above the solidus for silicate rocks. The presence of such a steam atmosphere during accretion may have significantly influenced the early thermal evolution of both Earth and Venus. © 1988."
"7006458649;6603614180;","Investigation of the cloudiness-Albedo feedback using analogue satellite images",1988,"10.1016/0169-8095(88)90034-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024190461&doi=10.1016%2f0169-8095%2888%2990034-8&partnerID=40&md5=f62d65138814d16d233f43edadf4b65e","A classical assumption for the dependence of planetary albedo on horizontal cloud coverage (α = α0 (1 - n) + αnn) is empirically verified for two areas in the Carpathian Basin (Hungary). The albedo values are derived from METEOSAT-2 analogue images by a special technique developed by Rimóczi-Paál and cloudiness is determined visually from the same images. A filtering by averaging of 3-7 pictures of the same day is applied to decrease the likely errors due to differences in the slope angle. A close linear regression between albedo and cloudiness is established with a regression coefficient close to αn-α0, but the parabolic fit shows considerable differences in ∂α/∂n for different values of n. For climate-modelling purposes the subsample of medium cloudiness (0.31 ≤ n ≤ 0.70) is also investigated. Linear and parabolic regressions give less accurate but still highly significant fit with about one half of total variance in albedo ""explained"" by cloudiness changes. These calculations based on half-yearly grouped subsamples are repeated for 3-monthly grouped ones, with no marked difference in conclusions. The estimated value of ∂α/∂n is higher than αn - α0 especially for the warm/warming-up half-year, but the difference is not much beyond the error deviation of the regression estimations. The peculiar importance of accurate quantitative determination of cloudiness-albedo feedback is demonstrated using an independent estimation of the sensitivity of regional cloudiness in Hungary on hemispheric temperature changes. © 1988."
"7004852764;","Operational remote sensing in the United Kingdom: problems of image acquisition",1988,"10.1109/igarss.1988.569495","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024196175&doi=10.1109%2figarss.1988.569495&partnerID=40&md5=e2ae53d9c5bf2d2ade544c54286c80f2","A study of historical acquisition of cloud-free Landsat MSS imagery of Britain, based on ""quicklook' prints, indicates that operational remote sensing applications requiring imagery within specific time intervals each year are impractical in the British climate. Numerous other applications with less stringent image acquisition requirements are shown to be practical with current sensor systems. The need for improvement in contextual classificaiton procedures to make maximum use of available data is emphasised, and it is suggested that operation remote sensing has a more urgent requirement for additional co-orbiting satellites of Landsat and SPOT spatial and spectral resolution than for new single satellites carrying more advanced sensors. -Author"
"7006689276;","What are the radiative and climatic consequences of the changing concentration of atmospheric aerosol particles?",1988,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024260458&partnerID=40&md5=1484b05a5fe27c73848b73c8ca8a3b92","The possible latitude-dependent, man-made albedo changes is derived from radiation budget calculations based upon vertical aerosol particle concentration profiles for three size classes resulting from a two-dimensional (resolving latitude and height) global aerosol transport mode. The main result, albedo enhancement (i.e., reduced greenhouse effect of the atmosphere) is caused by cloud albedo increase rather than by enhanced backscattering from cloudfree parts of the atmosphere. The strong dependence of the local planetary albedo change on aerosol particle size distribution change and soot content underlines the need for more reliable input parameters and more sophisticated models before the sign and the relative magnitude of an aerosol climate signal, as compared to the additional greenhouse effect by increased trace gas concentration, may be given with higher reliability. -from Author"
"36107698500;","The variations of atmospheric carbon dioxide at Alert and Sable Island, Canada",1988,"10.1016/0004-6981(88)90044-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023823551&doi=10.1016%2f0004-6981%2888%2990044-3&partnerID=40&md5=40a429c663b73d94407eb4fd203bc4c0","It has been observed that atmospheric carbon dioxide (CO2) is increasing at Alert and Sable Island at a rate of about 1.25 ppm a-1. Seasonal cycles of atmospheric CO2 are quite evident there, with the occurrence of minimum values in the late summer. Maximum values occur in the late winter at Sable Island in the mid-latitude and in April or May at Alert in the Arctic. Although anthropogenic emissions of CO2 into the Arctic atmosphere are 2-3 orders of magnitude smaller than those at mid-latitudes, a higher concentration and larger seasonal variation are observed at Alert than at Sable Island. At Alert, a CO2 minimum in the seasonal cycle in the summer is associated with a lower frequency of atmospheric inversions, and increased occurrence of stratus clouds, precipitation and cyclonic activities. The frequency of occurrence of relatively low values of CO2 with precipitation and fog during the period of 1981-1985 was 64.3 % at Alert and 62.0% at Sable Island. Air parcel back-trajectory analyses have indicated that at Sable Island relatively low values of CO2 are associated with air parcels generally coming from the N or SE (oceanic regions) to the site. In contrast, relatively high values are associated with 5-day trajectories arriving from the W or WSW, i.e. from the continent. The 5-year climatology of air parcel trajectories arriving at Alert showed that low values of atmospheric CO2 concentrations are usually associated with S-SW airflows, while relatively high values of CO2 are generally associated with a long trajectory originating in the Soviet Arctic. In particular, high values of CO2 concentrations occur in the late spring under the meteorological conditions of a pronounced temperature inversion, high solar radiation and calm or light winds at the surface. These conditions are favourable for high air pollution potential in the Arctic and for CO2 episodes at Alert. It is believed that Arctic air pollution is a cause of perturbation in radiation budgets especially during spring. © 1988."
"6602392808;6603797887;","DIAGNOSTIC CALCULATIONS OF ZONAL CLOUD COVER AND RADIATION FLOWS.",1987,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023564915&partnerID=40&md5=639512ec9a523084c811c2be2134e350","Proposed is a method of forecasting cloud cover as a function of relative humidity with the aid of comparatively simple analytical expressions intended for use in numerical models of the climate. According to climate data we evaluate its accuracy and the accuracy of calculating the constituents of the radiation balance of the Earth-atmosphere system with the aid of the developed cloud-radiation unit."
"7003830856;7004818189;6603792921;","Pollution and cloud reflectance",1987,"10.1007/BF00120449","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023480960&doi=10.1007%2fBF00120449&partnerID=40&md5=35ff29154f013fca1d86f486ef4f0f50","Conventional power plants are prolific sources of cloudnucleating particles. Consequently clouds forming in air influenced by such emissions contain higher concentrations of cloud droplets than would prevail in clean conditions; optical properties of clouds are thereby modified, causing them to reflect more sunlight and transmit less. That has obvious consequences for climate physics, but it may also be relevant for mesoscale processes since quite substantial energy changes are involved. Ships constitute isolated sources in an environment that is often quite clean, and when low thin cloud layers are present, ships delineate their courses in satellite images by bright lines. These lines are caused by the above-mentioned increase in reflectance, providing, on a scale of tens to hundreds of kilometers, a realization of an effect which on a climatic scale cannot be directly observed (but which is likely to be comparable in magnitude to the CO2 effect, but oppositely directed). © 1987 D. Reidel Publishing Company."
"7403029589;7007140056;","The effects of aerosols on the response of a two-dimensional zonally-averaged climate model",1987,"10.1007/BF00867415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250106039&doi=10.1007%2fBF00867415&partnerID=40&md5=995b6e1ee8f6a33b2ac676b4e7d46996","The response of climate processes to changes in aerosols is investigated using a two-dimensional zonally-averaged climate model. To account for the spatial and temporal heterogeneities of aerosol distributions, a strongly scattering maritime aerosol over ocean and a strongly absorbing rural aerosol over land are used in the layer between the surface and the 700 mb level. The effects of aerosols, gases and clouds on the radiative transfer are computed concurrently using a parameterized form of a two-stream approximation. Aerosols induce a reduction of the solar absorption at the surface and an enhancement of atmospheric absorption. The resulting changes in the climate model parameters are not only a function of the radiatively-active atmospheric constituents, but also of the amplifying or dampening effects of feedback processes employed in the model calculations. For the specified aerosol types and the optical thickness distribution given by Potter and Cess, the annual temperature change at the surface is -2.1 °C with ice-albedo feedback. Without ice-albedo feedback the corresponding value is -1.4 °C. In the present study aerosols produce a cooling effect in the atmosphere at all latitudes. © 1987 Springer-Verlag."
"7005533663;7004201998;","Cloud climatologies from space and applications to climate modelling.",1987,"10.1007/978-94-009-3881-6_19","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023518186&doi=10.1007%2f978-94-009-3881-6_19&partnerID=40&md5=ebaec149156d7dac6e3758df4e326a90","Global satellite-derived cloud climatologies are considered and the results of an automated cloud analysis model are presented. The zonal distribution of cloud is applied to the radiative fluxes as predicted by an energy balance model. Special channel cloud discrimination is discussed with reference to Landsat thematic mapper. -Authors"
"7005729142;56627414400;7409924037;7102290666;","Symposium on clouds and radiation.",1987,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023488269&partnerID=40&md5=1ac37e0efe902b75ca50c0714a91e5c1","The highly interactive relationship between clouds, radiation, and dynamics suggests that these components of the climate system be studied together. In pursuit of this objective, the International Association of Meteorology and Atmospheric Physics (IAMAP) organized the Symposium on Clouds and Radiation, which was held during the IAMAP/International Association for Physical Sciences of the Oceans (IAPSO) Joint Assembly in Honolulu, Hawaii, August 5-16, 1985. The 15 papers presented at the Symposium generally fell into three categories: the radiative properties of clouds, the remote sensing of cloud properties; and the utilization of earth radiation budget data for climate studies. This issue of the Journal contains papers presented at the Symposium.-from Editors"
"7103246957;57203400519;","Thermodynamic constraint on the cloud liquid feedback in climate models",1987,"10.1029/JD092iD07p08483","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023467577&doi=10.1029%2fJD092iD07p08483&partnerID=40&md5=07ccd931aa2123b9ce5768a1207c779e","The cloud liquid water feedback in climate models consists of the increase (decrease)oi in optical depth of clouds resulting from higher (lower) liquid water contents that might accompany tropospheric warming (cooling). The change in cloud liquid water with temperature is shown to depend on the rate of change of the slope of the moist adiabat with respect to temperature, and it is a strong function of temperature. The value of this rate of change in the tropics is about half that in mid and high latitudes and is much less than the value obtained by assuming that liquid water scales with the saturation mixing ratio. -Authors"
"6701607011;7004540083;","Time-cumulated visible and infrared histograms used as descriptor of cloud cover",1987,"10.1016/0273-1177(87)90138-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-45949126508&doi=10.1016%2f0273-1177%2887%2990138-4&partnerID=40&md5=8ea446563cbaa7f3fd7df2f50c5300e0","To study the statistical behavior of clouds for different climate regimes, the spatial and temporal stability of VIS-IR bi-dimensional histograms is tested. Also, the effect of data sampling and averaging on the histogram shapes is considered; in particular the sampling strategy used by the International Satellite Cloud Climatology Project is tested. © 1987."
"7005070958;7102268722;","Exploratory studies of cloud radiative forcing with a general circulation model",1987,"10.1111/j.1600-0870.1987.tb00321.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981683877&doi=10.1111%2fj.1600-0870.1987.tb00321.x&partnerID=40&md5=c9128fbc62a0e9a3a8e1dbcc2ff09678","Cloud radiative forcing constitutes the radiative impact of clouds upon the earth's present climate, while cloud radiative feedback is the change in this forcing associated with climatic change. The present study addresses two issues concerning cloud radiative forcing. The first is that an intercomparison of cloud radiative forcing, as predicted by six different general circulation models, shows a considerable lack of agreement, underscoring the need for an improved understanding of cloud/radiation interactions within such models. The second issue pertains to an examination of strategies by which model‐predicted cloud/radiation interactions should be compared with satellite‐derived data sets. 1987 Blackwell Munksgaard"
"7007026915;","Satellite-derived attributes of cloud vortex systems and their application to climate studies",1987,"10.1016/0034-4257(87)90062-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023383715&doi=10.1016%2f0034-4257%2887%2990062-9&partnerID=40&md5=b2842b5df79b17f4ed2d2425e4f121c7","Defense Meteorological Satellite Program (DMSP) visible and infrared mosaics are analyzed in conjunction with synoptic meteorological observations of sea level pressure (SLP) and upper-air height to derive composite patterns of cyclonic cloud vortices for the Northern Hemisphere. The patterns reveal variations in the structure and implied dynamics of cyclonic systems at different stages of development that include 1) increasing vertical symmetry of the lower-level and upper-air circulations and 2) decreasing lower-tropospheric thicknesses and temperature advection, associated with increasing age of the vortex. Cloud vortices are more intense in winter than in summer and typically reach maximum intensity in the short-lived prespiral signature stage. There are major structural differences among frontal wave, polar air, and ""instant occlusion"" cyclogenesis types. Cyclones in the dissipation stage may reintensify (deepen), as denoted by the appearance in the imagery of an asymmetric cloud band or a tightened spiral vortex. The satellite-derived statistics on cloud vortex intensity, which are seasonal- and latitude- as well as type-dependent, are applied to a preliminary examination of the synoptic manifestations of seasonal climate variability. An apparently close relationship is found, for two winter and spring seasons, between Northern Hemisphere cyclonic activity and variations in cryosphere variables, particularly the extent of Arctic sea ice. The results may indicate that increased snow and ice extent accompany a southward displacement of cyclonic activity and/or a predominance of deeper systems. However, there is also a strong regional dependence to the ice-synoptics feedback. This study demonstrates the utility of high resolution meteorological satellite imagery for studies of climate variations (climate dynamics). © 1987."
"7007131982;","Meteorological office catches FIRE!",1987,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023500648&partnerID=40&md5=acab4e27929497a8033e4283ef0a7585","During June and July 1987, a field experiment designed to study in detail the processes active in extensive low-level cloud sheets is being held off the coast of California. This is one part of a larger programme called FIRE which aims to investigate the properties of those cloud fields which play an important role in determining the earth's climate through cloud-radiation feedback mechanisms. This article briefly describes the major objectives of the programme and the observations which will be made during the field experiment. -Author"
"35464731600;","The effect of subpixel clouds on remote sensing",1987,"10.1080/01431168708948693","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023524771&doi=10.1080%2f01431168708948693&partnerID=40&md5=2a0a58a8715e0f81ac7d1181c3784cf9","The effect of subpixel clouds on remote sensing of the surface reflectivity and of the vegetation index was numerically simulated for a thin layer of rectangular clouds. The simulation is for a 4x4km2 field of view (e.g. the low resolution NOAA-AVHRR images). A fixed cloud reflectivity was used as well as an empirical cloud model for eight cloud types. In the empirical models the cloud reflectivity varied with cloud fraction. A cloud fraction of 20 percent, in a pixel with surface reflectance of0 05, can increase the apparent surface reflectance by 0 02 for a model of strato-cumulus and by 0-08 for a fixed cloud reflectance of Rc =0-5. By using measured cloud fraction probability distributions in several climatic regions (not including a tropical climate) it was found that the cloud effect can be eliminated if the best remote sensing case out of about four independent cases is chosen. This corresponds to 8-16 observation days. In order to estimate the cloud effect on remote sensing of a particular area it is necessary to measure the probability distribution of the cloud fraction and the dependence of the cloud reflectance on the cloud size. Subpixel clouds were shown to affect the variation of upward radiance across an image. Therefore the standard deviation of the radiances over a uniform area can be used to sense the presence of the residual cloud effect. © 1987 Taylor &amp; Francis Group, LLC."
"57196297315;","Mass extinctions: volcanic, or extraterrestrial causes, or both?",1987,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023501697&partnerID=40&md5=586203fdb2162f840978a9de3dec80aa","The identification of an iridium spike in a clay deposit at the boundary between the Cretaceous and the Tertiary suggested a collision of the Earth with a giant asteroid and provided evidence for the catastrophe theory for the extinction of many life forms. This led paleontologists to re-examine the fossil record to see if it is consistent with a single extraterrestrial influence. The result has been a picture of stepwise extinctions of species over periods of millions of years. This has been interpreted by some as the result of several impacts with comets from a disturbed comet cloud, whilst others contend that terrestrial events associated with vulcanism, climate change and sea-level regression could have been sufficient cause and that any association with extra-terrestrial events is coincidental.-J.Harvey"
"6701691239;","Remote sensing applications in the meteorology and operational hydrology programmes of WMO",1987,"10.1016/0273-1177(87)90123-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-50849148415&doi=10.1016%2f0273-1177%2887%2990123-2&partnerID=40&md5=e3dcd24a916726ca2b3cd29268f3dbba","Remote sensing from satellites continues to have a very large impact on the activities of the World Meteorological Organization (WMO) and continues to provide very great benefits to meteorological services throughout the world. Meteorological satellites provide remotely sensed data which can be converted into meteorological measurements such as cloud cover, cloud motion vectors, surface temperature, vertical profiles of atmospheric temperature and humidity, snow and ice cover, ozone and various radiation measurements. The meteorological satellites are part of the global operations of the World Weather Watch Programme which serves as the basic programme of the WMO by supporting other programmes and activities. Satellite measurements are critical to the success of many different components in the World Climate Programme. Special projects are being designed for the 1990s to take advantage of the data from satellite systems designed primarily to provide land or ocean observations. The Applications of Meteorology Programme makes use of remotely sensed data to provide products and services to agricultural, aeronautical and marine activities. The transfer of knowledge and technology in satellite remote sensing applications are important elements of the Technical Co-operation and the Education and Training Programmes. © 1987."
"7004225428;","Variability (in time) of the isotopic composition of precipitation: consequences regarding the isotopic composition of hydrologic systems.",1987,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023509302&partnerID=40&md5=802b349cb86095a6f7ba3416ff5aaa85","The stable isotopic signature in precipitation is primarily imposed by the synoptic history of the air masses, namely, by the vapour origin and the rainout history en route. Mixing patterns in the cloud and rain intensity affect the isotopic composition of rain to some extent. During the recharge to groundwaters, additional isotopic change may occur due to isotope fractionation which accompanies evaporative water loss from the surface or soil (mainly in arid zones), or selection of part of the rainfall by run-off or transpiration. Changes in the meteorological pattern and climate express themselves 'isotopically' both due to the changing synoptic patterns and the secondary isotope fractionation and selection which accompany the rain-forming and the groundwater recharge process. For the latter case, the rain intensities and the intervals between individual rain events are of major importance. (Author's abstract)-A.W.H."
"7005513582;7202155374;","A study of the radiative effects of enhanced atmospheric CO2 and CH4 on early earth surface temperatures.",1987,"10.1029/JD092iD03p02991","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023104001&doi=10.1029%2fJD092iD03p02991&partnerID=40&md5=67133acbe48de6795abe49dd1a7b1315","Large concentrations of atmospheric CO2 in the atmosphere of the early earth have been proposed as a possible explanation of the apparent absence of frozen earth in spite of a faint early sun. However, the most thorough treatments of this question apparently disagree as to the warming effects of large amounts of CO2. We recalculate the evolution of surface temperature over the last 4.25 billion year time period, using the same scenario for CO2 partial pressures and solar constant as employed by the previous authors. Using the concept of direct radiative forcing, we present analytic relations between the solar luminosity and CO2 mixing ratio required to maintain the troposphere close to its present thermal structure. We also present new braodband parameters for the 961 and 1064 cm-1 CO2 bands that can be used in climate models. We also consider the direct radiative forcing of large amounts of CH4, or changes in model clouds, and discuss how these might reduce the CO2 mixing ratio required to balance the faint early sun. -from Authors"
"6701791841;","The radiation climate of the dead sea",1987,"10.1002/joc.3370070305","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023467240&doi=10.1002%2fjoc.3370070305&partnerID=40&md5=feb4bbe86abb0c04e72e4205d77346dd","Three years of continuous measurements on the NW coast of the Dead Sea, together with a series of shipborne observations made above its water surface, were used to characterize and analyze the radiation climate of the sea. Incident global radiation on the coast, averaged 6.64 GJm−2 per year, less than values measured both at sea and at nearby pyranometer stations despite the greater cloud cover of the latter. The relatively low insolation was attributed to the considerable back scatter from the sky shown by the high values of diffuse sky radiation recorded even during cloudless conditions. Short‐wave radiation reflected from the sea was calculated, on the basis of a quadratic relationship between reflectivity and solar altitude, to total O50GJ m−2 annually. Above a critical solar altitude of 45° reflectivity averaged 6 per cent. Monthly values of reflectivity from the Dead Sea agreed with those calculated for a standard sea surface. Atmospheric long wave radiation measured on the coast totalled ll.44 GJ m−2 annually. Its seasonal and diurnal variations closely followed those in air temperature. Small variations in the apparent sky emissivity, which averaged 0.80, could be accounted for by reference to accompanying changes in the water content and transmissivity of the atmosphere. Midsummer and midwinter in situ determinations of the emissivity of the Dead Sea yielded near‐black body values which, with the high surface temperatures of the sea, resulted in a terrestrial radiation flux totalling 14.69 GJ m−2 annually. Direct pyrradiometer measurements over the Dead Sea were used to establish the accuracy of long term estimates of the radiation balance of the sea and to develop a method of calculating it from routine, shore‐based measurements of global radiation. The radiation balance of the Dead Sea, normalized to the incident radiation, was 0.45,22 per cent less than the average for eight other non‐saline water bodies in comparable mid‐latitude climates. The relatively low radiation balance of the Dead Sea was attributed to the enhanced long‐wave radiation loss caused by the elevated surface temperature of its salt‐saturated waters. Thus the salinity of the Dead Sea reduces its evaporation loss by two mechanisms; the direct effect of the reduced vapour pressure of the water surface and the indirect effect of the reduced radiation balance. Copyright © 1987 John Wiley &amp; Sons, Ltd"
"55531982800;7006652595;26643081200;6507069287;7003799892;","The possible applications of Meteosat for monitoring the rain season in the Sahel zone: The case of Senegal",1987,"10.1016/0273-1177(87)90125-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-38249037097&doi=10.1016%2f0273-1177%2887%2990125-6&partnerID=40&md5=ff6589a3159d6fd557effd377c0b1aac","The use of geostationary meteorological satellites for monitoring climate is relatively well known. However, the application of satellite data for agronomical purposes is still far form being operational. Recent work shows the possibility of establishing statistical models adapted to each region which can predict rain to within a time interval of 12 to 24 hours, based on the analysis of cloud cover. In the same way, thermal IR images may be used, employing the quasi-linear relationship between surface temperature and real evapotranspiration E.T.R. This is the objective of the project on monitoring the hydric balance in Senegal, associating INRA-IRAT and LERTS in France, ISRA and Meteorologie Nationale in Senegal. The first results obtained by Assad et al from two Meteosat images taken during 1979 establishing an inverse relationship between surface temperature and rain, over the total area of Senegal, were maintained for 16 images taken during the 1984 and 1985 rain period. Their analyses show that it is possible : - To identify the most favorable sowing periods, - to diagnose periods of high climatic risk for crops, and to cartograph rain distribution from spatial variations in surface temperature. © 1987."
"57198940711;36900406400;7102796343;","The use of AVHRR data in operational agricultural assessment in Africa",1987,"10.1080/10106048709354080","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3342950827&doi=10.1080%2f10106048709354080&partnerID=40&md5=d6f5bfb1de0c081891e11ed6dce241d8","The Assessment and Information Services Center (AISC) of the National Oceanic and Atmospheric Administration (NOAA), National Environmental Satellite, Data and Information Service (NESDIS) has been producing operational agricultural assessments since 1979. These activities provide drought early warning alerts and climate impact assessment to national and international agencies which require such information for disaster preparedness and agricultural assessment purposes.Data from the Advanced Very High Resolution Radiometer (AVHRR) aboard the NOAA polar‐orbiting satellite series have been used operationally in these assessment tasks since 1982. In 1985 and 1986, the use of satellite data has focused on medium resolution Global Area Coverage (GAC) data with an emphasis on the Sahel and Hom countries of Africa.In an operational context, satellite data are received from the Satellite Data Services Division of NOAA on a weekly basis from May through September. These data are processed into images over ten‐day periods in order to remove as many clouds as possible from the scene. They are further processed according to a unique color system designed to maximize their qualitative interpretability. The data are then analyzed on a weekly basis according to their normalized vegetation index (NVI) values as plotted on a spatial/temporal continuum.These satellite data, used in the context of agricultural assessment activities, are represented in two of three subsystems which are used to verify one another in the agricultural assessment process. © 1987 Taylor & Francis Group, LLC."
"7005533663;","Increasing cloud in a warming world",1986,"10.1007/BF00139074","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022882339&doi=10.1007%2fBF00139074&partnerID=40&md5=a08b0438e6d31b716f79987534f93ef6","Cloud amount records for the U.S.A. have been analyzed in the context of the 'warming world' analogue model described by Lough et al. (1983). Cloud amount increases over practically the entire U.S.A. in all seasons. This result considerably strengthens the more tentative conclusion of Henderson-Sellers (1986) that cloud amount increases over Europe in the same warming world scenario. These results are in contrast to the few numerical model predictions of cloud changes in warming world experiments. A possible, rather tantalizing, conclusion is that current GCM cloud prediction schemes tend to enhance temperature increases through cloud-climate feedback whereas the historical data could suggest a negative feedback. Part, possibly all, of this difference may be the result of the fundamental distinction between the two experimental scenarios: the equilibrium change modelled by GCMs as compared to the smaller transient change represented by the historical analogue. On the other hand the current 'real-world' experiment is, itself, a transient change in boundary and atmospheric conditions. At the least, surface-observed cloudiness seems to offer a useful and complementary data source with which to examine one aspect of the performance of numerical climate models. © 1986 D. Reidel Publishing Company."
"6603445356;","OBJECTIVE ANALYSIS OF DEW POINT DEFICIT IN THE TROPOSPHERE.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023027264&partnerID=40&md5=7a794eae6b0c159626a5effd7ca9ce5f","Described is a scheme for operational objective analysis of dew point deficit at isobaric surfaces of 925, 850, 700, 500, and 400 gPa, constructed on the basis of the method of optimal interpolation of meteorological observations. The source data consist of aerological dispatches in TEMP and TEMP-SHIP codes (parts A and B) and satellite dispatches in SATEM code. The developed procedure for monitoring data on dew point deficit consists of climate, vertical, and comprehensive monitoring. The latter includes horizontal statistical monitoring combined with climate monitoring of the vertical relationships of dew point deficit. Results are given for the comparison of objectively analyzed fields of dew point deficit with fields subjectively analyzed by the analyst and with maps of cloud cover."
"7003935665;7006376161;7404334532;","Atmospheric science on the Galileo mission",1986,"10.1007/BF00200817","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0013530294&doi=10.1007%2fBF00200817&partnerID=40&md5=44572b733964ba4ea8eb666b9e7e033a","Observations from the ground and four fly-by spacecraft have provided initial reconnaissance of Jupiter's atmosphere. The Pioneer and Voyager data have raised new questions and underlined old ones about the basic state of the atmosphere and the processes determining the atmosphere's behavior. This paper discusses the main atmospheric science objectives which will be addressed by the Galileo (Orbiter and Probe) mission, organizing the discussion according to the required measurements of chemical composition, thermal structure, clouds, radiation budget, dynamics, upper atmosphere, and satellite atmospheres. Progress on the key questions will contribute not only to our knowledge of Jupiter's atmosphere but to a general understanding of atmospheric processes which will be valuable for helping us to understand the atmosphere and climate of the Earth. Realization of the atmospheric science objectives of the Galileo mission depends upon: (a) coordinated measurements from the entry probe and the orbiter; (b) global observations; and (c) observations over the range of time-scales needed to characterize the basic dynamical processes. © 1986 D. Reidel Publishing Company."
"55388515800;24789543700;7403932015;","A global annually-averaged climate model with cloud, water vapor and CO2 feedbacks",1986,"10.1007/BF02678652","https://www.scopus.com/inward/record.uri?eid=2-s2.0-51649149627&doi=10.1007%2fBF02678652&partnerID=40&md5=0559c53c9d643456d6c53732fef77ac9","In consideration of the radiation transfer, latent and sensible heat exchange between oceans and atmosphere, a three-dimensional autonomous nonlinear ordinary differential equation is established by statistical parameterization method. The variables of the model are the mean ocean surface temperature Ts, mean atmospheric temperature Ta and atmospheric relative humidity f, and the feedbacks of clouds, water vapor and CO2 are involved. The steady state corresponding to the present-day climate can be obtained from this model. The analysis of parameter sensibility in the steady state indicates that clouds have considerable negative feedback effects and water vapor may affect the sign of CO2 feedback. The stability analysis of the steady state to small disturbance indicates that with increase of the positive feedback effect of clouds, the steady state goes through such a structural variance series as a stable node→a stable focal point→an unstable focal point→an unstable node, and when the steady state becomes unstable it undergoes a subcritical Hopf bifurcation. When the steady state is at a focal point, the periodic oscillation solutions of damping or amplifying can be obtained with the period being about two years. © 1986 Advances in Atmospheric Sciences."
"6701652286;7102875645;","An investigation of cloud cover change in response to thermal forcing",1986,"10.1007/BF00158967","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022660728&doi=10.1007%2fBF00158967&partnerID=40&md5=0402c32885bef946a374964cafc59097","The role of cloud cover in determining the sensitivity of climate has been a source of great uncertainty. This article reviews the distributions of cloud cover change from several climate sensitivity experiments conducted at the Geophysical Fluid Dynamics Laboratory of NOAA (GFDL) and other institutions. Two of the sensitivity experiments conducted at GFDL used a general circulation model with a limited computational domain and idealized geography, whereas three other experiments were conducted by the use of a global model with realistic geography. A thermal forcing imposed was either a change of solar constant or that of the CO2-concentration in the atmosphere. It was found that in all five cases, clouds were decreased in the moist, convectively active regions such as the tropical and middle latitude rainbelts, whereas they increased in the stable region near the model surface from middle to higher latitudes. In addition, cloud also increased in the lower model stratosphere and generally decreased in the middle and upper troposphere for practically all latitudes. A comparison of the cloud changes obtained from investigations carried out at other institutions reveals certain qualitative (but not necessarily quantitative) similarities to the GFDL results. These similarities include a general reduction of tropospheric cloud cover especially in the vicinity of the rainbelts, a general increase of lower stratospheric cloud cover for almost all latitudes and an increase of low stratiform cloud in high latitudes. © 1986 D. Reidel Publishing Company."
"7005533663;","Cloud changes in a warmer Europe",1986,"10.1007/BF00158968","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0002102072&doi=10.1007%2fBF00158968&partnerID=40&md5=d4720cb6e130fbd827e40b653c9da663","Cloud cover records for western Europe have been analysed in the context of the 'warming world' analogue model described by Lough et al. (1983). It is found that cloud cover has generally increased in moving from a cold period (1901-1920) to a warm period (1934-1953). The exception to this general trend is over the central part of the area considered (Germany, France and some parts of Spain) where there is a tendency towards decreasing cloud as warming occurs. While the results presented here are not closely correlated with the temperature and precipitation results of Lough et al. (1983), there is support for their hypothesis that cloudiness increased in autumn over northern Europe. The suggestion that successful performance of numerical climate models in seasonal simulations might demonstrate adequacy in other climatic simulation modes is also examined It is shown that whilst there is good agreement with observations in one such numerical model in the seasonal simulation, there is no agreement in the case of a 'warming world' in either the direction or the amount of cloudiness change. © 1986 D. Reidel Publishing Company."
"56283400100;55888426900;","Sensitivity of the climate simulated by a GCM to the parameterization of stratus clouds.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022851773&partnerID=40&md5=9a6ce351e56f8f51c55a899437e02fc8","We have designed a parameterization of the stratus cloud cover for use in the LMB GCM. The surface covered by these clouds primarily depends on the distribution of the static energy. Results for a simulation of the climate of July are shown: the stratus clouds appear in the eastern part of the subtropical oceans, in agreement with the climatology and with the results of other models. The presence of stratus clouds induces a cooling of the atmosphere, which is damped over the oceans because in our experiments the sea-surface temperature is prescribed. They also cause a clear enhancement of the stationary eddies. But their radiative impact on the mean hydrological cycle seems small. -Authors"
"7006550762;","The dynamics of warm and cold climates.",1986,"10.1175/1520-0469(1986)043<0003:tdowac>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022923656&doi=10.1175%2f1520-0469%281986%29043%3c0003%3atdowac%3e2.0.co%3b2&partnerID=40&md5=0e5665fe03f2d1a1c61842d358052ade","The atmospheric dynamics of five different climate simulations with the GISS GCM are compared to investigate the changes that occur as climate warms or cools. There are two ice age simulations, the current and doubled CO2 climates, and a simulation of the warm Cretaceous. The results are compared with those of other models, as well as to paleoclimate and recent observations. The study shows that many zonally averaged processes do not change systematically as climate changes. Additional results show that the relative humidity remains fairly constant as climate changes. The ratio of stationary to transient eddy kinetic energy also remains relatively constant. Eddy energy transports increase in colder climates, primarily due to changes in the stationary eddy transports. Cloud cover decreases as climate warms due to decreases in low-level clouds. The lapse rate in all the simulations follows the moist adiabatic value at low latitudes, and is close to the critical baroclinic adjustment value at upper midlatitudes. The latitudinal temperature gradients at midlatitudes of both the sea surface temperature and the vertically integrated air temperature are very similar in the diverse climates. - from Author"
"7102018821;","Influence of cirrus clouds on weather and climate processes: a global perspective.",1986,"10.1175/1520-0493(1986)114<1167:IOCCOW>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022846515&doi=10.1175%2f1520-0493%281986%29114%3c1167%3aIOCCOW%3e2.0.CO%3b2&partnerID=40&md5=bb6e71b82fa09098b802eeb1dbc40099","To place the relevance and importance of cirrus composition, structure and radiative properties into a global perspective, we present pertinent results derived from simulation experiments utilizing models with varying degrees of complexity, which have been carried out for the investigation of the influence of cirrus clouds on the thermodynamics and dynamics of the atmosphere. Suggestions are outlined for cirrus-radiation research activities aimed toward the development and improvement of weather and climate models for a physical understanding of cause and effect relationships and for prediction purposes. -from Author"
"7103271625;","Sensitivity of the thermal balance in a general circulation model to a parameterization for cumulus convection with radiatively interactive clouds.",1986,"10.1175/1520-0469(1986)043<2277:SOTTBI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022833590&doi=10.1175%2f1520-0469%281986%29043%3c2277%3aSOTTBI%3e2.0.CO%3b2&partnerID=40&md5=42b3b8474fb31c5be81ca12febd445e1","The dependence of the thermal balance of a general circulation model on the parameterization of cumulus convection is investigated. Incorporation of a Kuo-type cumulus parameterization into the NCAR community climate model decreases temperatures in most of the lower and middle tropospheres while increasing temperatures slightly at the tropopause, decreases both relative and specific humidities in large parts of the lower troposphere, and also reduces cloud cover and tropical precipitation. The dependence of the circulation sensitivity to cumulus parameterization on cloud-convection feedback and the penetrative extent of convection is found to be significant. The penetrative depth of convection is especially important. Changes in cloudiness associated with the Kuo parameterization alter radiative forcing so as to reduce the sensitivity of the community climate model to the cumulus parameterization.-from Author"
"7201611711;","A climate overview of the Canadian inland seas.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022841196&partnerID=40&md5=86d90b308bfe68b2f9aaf08cd5e96834","The Hudson Bay and James Bay region is abnormally cold compared with other lands at the same latitude. Few climatic records were kept until 1931 - most of the modern climatic record has been built up over the last 3 decades. This chapter discusses climatic controls; seasons; temperature; wind; precipitation, cloud and fog; sea state; and climate variability and change.-T.Kennard"
"7003597653;7202746102;6507775652;6506819791;6505824944;57217911723;","The '31' procedure applied to the retrieval of meteorological and climate parameters from NOAA-7.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022823244&partnerID=40&md5=62e7de557777351e4e98361a80d24a2d","The 31 (Improved Initialization Inversion) method has been designed for retrieving meteorological or climatic parameters from satellite vertical sounders and first applied to NOAA-7, the third of the TIROS-N operational weather satellites series. Presents an overview of the 31 method: initialization of the inversion problem including cloud detection and cloud clearing, atmospheric temperatures retrieval, cloud parameters retrieval, atmospheric water vapor retrieval and surface temperatures retrieval. Presents and discusses the results of an application of the algorithm to NOAA-7 for the March 4-5, 1982 ALPEX (ALPine EXperiment) IOP (Intensive Observing Period), including the thermal and moisture structure, cloud parameters (heights and amounts), and surface parameters (temperature, microwave emissivity).-from Authorsweather satellites retrieval atmospheric temperature humidity clouds Lab de Meteorologie Dynamique du CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex, France."
[No author id available],"Atlas of Australian resources. Third series, volume 4. Climate.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040870582&partnerID=40&md5=cd97a5f7a240a5d6a0d48524e573d727","This volume of Australia's national atlas provides a comprehensive guide to the continent's climate. After a brief introduction which explores the relationships between atmospheric circulation and day to day weather, each of the major climatic elements - Rainfall, Temperatures, Wind, Sunshine and Cloud, and Humidity - are covered in detail. The final section of the volume describes the pervasive influence climate has on land-use and the major climatic hazards, such as droughts, cyclones and floods, which are so much a part of Australian life. It also includes maps and descriptions of the climate of each of Australia's capital cities, where nearly two-thirds of the population live.-Authors"
"7404894746;7406514318;","Diurnal variation and cloud in a general circulation model",1986,"10.1002/qj.49711247205","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022843301&doi=10.1002%2fqj.49711247205&partnerID=40&md5=31c3f78f73f27a394f7ee41b62056149","It is shown that changing the resolution of the diurnal cycle of cloud and radiative fluxes in an atmospheric general circulation model can affect the simulated climate. The effect on radiative forcing of using a temporal resolution which is unable to represent accurately the phase of diurnal variation in cloud is illustrated using a radiative‐convective version of the model. Similar results are found in the full model simulation for July, especially over land in the tropics. A detailed study of the changes over North Africa shows that the reduction in solar heating at the surface leads to a reduction in low‐level convergence and rainfall, and increased low cloud. The results indicate that cloud amounts need to be updated more frequently than four times a day if the model simulation is not to be degraded when the diurnal cycle is represented. Copyright © 1986 Royal Meteorological Society"
"7004286811;","First data from the earth radiation budget experiment (ERBE).",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022837833&partnerID=40&md5=99947054efc6c0b9ce3b0c3b32d85b15","The first data obtained from the Earth Radiation Budget Experiment (ERBE) are presented. These data include emitted infrared radiation, albedo, and estimated scene types for 15 November 1984, as well as measurements of the 'solar constant'. Images from the GOES on the same day are included for comparison with the ERBE scene identification. On an instantaneous basis, clouds appear colder and more reflective than seems to have been noted before. The experiment data will be applied to several key studies of cloud-radiation-climate interactions.-Author"
"57198456621;7401491382;","Parameterization of snow albedo for climate models.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022846602&partnerID=40&md5=fd14f359c6109c6650810b4d202071f7","General circulation models (GCMs) find that the response of climate to increases in CO2 is enhanced by the snow-albedo-temperature feedback. The results are very sensitive to the assumed value of snow albedo. Snow albedo, however, is highly variable, and it is not calculated accurately in present-day GCMs. We would like to replace the current simple empirical parameterizations of snow albedo with a physically-based parameterization which is accurate yet efficient to compute. Our approach is to develop simple functions which fit the spectrally-averaged results of a detailed theoretical model of the spectral albedo of snow which uses the delta-Eddington method for multiple scattering and Mie theory for single scattering. The spectrally-averaged snow albedo varies with snow grain size, solar zenith angle, snow cover thickness, underlying surface albedo (for thin snow), concentration of absorptive impurities in the snowpack, and cloud optical thickness (because clouds alter the solar spectrum at the surface). This method divides the solar spectrum into the two broad wavebands commonly used in climate models: visible and near-infrared. -Authors"
"7004027026;","Volcanoes, the stratosphere, and climate",1986,"10.1016/0377-0273(86)90025-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022923705&doi=10.1016%2f0377-0273%2886%2990025-9&partnerID=40&md5=5d228b3a40ee4166e203da6d7d7d81a3","A list of volcanic eruption plumes observed to ascend into or near the stratosphere since 1883 shows that the volcanoes divide readily into two groups, one at low and one at higher latitudes. A model for the rise of a buoyant volcanic plume rise as applied to volcanic eruptions is corrected for realistic temperature profiles and for the finite vertical extent of the resultant debris clouds. The utility of the model can be questioned, however, owing to the highly uncertain and variable nature of the efficiency of use of heat energy of buoyant rise. The observed correlation of stratospheric plumes with climatic effects indicates that those plumes nearer the equator have the largest impact on surface temperatures. Analysis of the observations also suggests that injection of debris into the stratosphere is more important in determining the effect on climate than either the total volcanic explosivity of the eruption or the actual height reached within the stratosphere. © 1986."
"7005228425;7102496779;7006634316;7005254328;27267529400;","Physical and chemical properties of Arctic aerosols and clouds.",1986,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022843307&partnerID=40&md5=e1bf1f17eaa76350c57d0390f991f4a2","This paper reviews aspects of Swedish arctic aerosol research, including aerosol particle size distribution and composition variability, and how the aerosol influences arctic climate. Possible reasons are discussed for large variations in winter and summer measurements of physical and chemical aerosol properties. Particle size distribution studies on formation, transformation and removal processes of the arctic aerosol indicate that the accumulation mode of the aerosol is narrow, with small median diameter compared to midlatitude aerosols; sulfate is the mass-dominant component. Model calculations evaluate different transformation pathways leading to sulfate particles. To assess meteorological effects of anthropogenic aerosols, local heating was calculated using measured aerosol properties and radiative transfer models; results indicated heating rates of 0.1 to 1.0 K/day. -from Authors"
"6602682502;","The effect of ozone photochemistry on atmospheric and surface temperature changes due to large atmospheric injections of smoke and NOx by a large-scale nuclear war",1986,"10.1016/0004-6981(86)90181-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022554266&doi=10.1016%2f0004-6981%2886%2990181-2&partnerID=40&md5=ef9602f94753d41bc303f1074a22c471","A coupled one-dimensional radiative-convective and photochemical diffusion model (RCP model), which takes into account the interaction of ozone photochemistry on climate, is used to investigate the possible effects of smoke and NOx generated by a large-scale nuclear war, on vertical temperature and ozone structure and surface climate. From the results of initial experiments with fixed O3 it is found that for the nuclear smoke injection scenario adopted in this study (similar to the base line case of Turco etal., 1983), the average sunlight intensities would be reduced drastically (up to 97%), leading to a large cooling near the surface (up to 38 K) and intense heating (up to 110 K) in the upper troposphere and lower stratosphere. Variation of surface albedo, water vapour and clouds with time following the smoke injection would further enhance the surface cooling and prolong the temperature perturbation. Further experimental results with O3 photochemistry interaction indicate that for the smoke and NOx nuclear injection scenario considered in this study, the total O3 column would decrease up to 50%, with a half recovery time of about 2 y. However more than half the total O3 column reduction is caused by the heating of the stratosphere by smoke injection. The effect of stratospheric O3 reductions on surface climate is not significant (less than 2.5 K. additional cooling). However the vertical temperature profile is altered in such a way that it would lead to a large increase in the thermal stability of the troposphere, while decreasing it in the stratosphere more than in the case of fixed O3. Also discussed are the solar u.v.-B flux changes at the surface which result from the presence of smoke in the atmosphere initially and from stratospheric O3 depletions as the smoke particles are removed from the atmosphere in time. © 1986."
"7007026915;","Synoptic‐dynamic character of ‘bursts’ and ‘breaks’ in the South‐West U.S. summer precipitation singularity",1986,"10.1002/joc.3370060604","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022841481&doi=10.1002%2fjoc.3370060604&partnerID=40&md5=1588b0b2e1a2142189c07f80498ada13","Marked intraseasonal variations in the intensity of the south‐west U.S. summer precipitation singularity (the ‘Monsoon’) are identified for the years 1980–1982 from a previously developed satellite cloud climatology. These ‘bursts’ and ‘breaks’ are examined synoptically by compositing sea level pressure and 500 mb height data. Both types of events are controlled by the upper‐level flow. This typically involves, for bursts, the intrusion into subtropical latitudes of a trough in the westerlies with attendant cold air advection. In conjunction with intense surface heating, this produces widespread atmospheric destabilization over the South‐west. Monsoon breaks are characterized by enhanced ridging of the Bermuda and North Pacific subtropical anticyclones with associated subsidence over southern Arizona/California. Between‐year differences in these composite patterns are identified, and it is suggested that wetter summers may be characterized by larger within‐season variations in 500 mb heights and isobaric curvature compared with drier summers. Several 500 mb synoptic types associated with burst events are determined subjectively, and composite patterns are derived. These indicate that bursts occasionally occur with anticyclonic conditions aloft, but the latitude of the ridge seems critical in determining the extent of moist air penetration from the south. Twice‐daily aerological soundings at five stations in the South‐west and northern Mexico are also used to determine the thermodynamic characteristics of bursts and breaks and the dominant source of monsoon moisture. Monsoon bursts in Arizona are evidently a combination of moisture from the Gulf of Mexico, transported on a light south‐easterly flow, and more rapid lower‐level ‘surges’ originating in the Gulf of California. Moisture from the latter source is transported rapidly into the Great Basin on a low‐level wind‐speed maximum of marked directional constancy. This study has implications for longer‐term summer rainfall‐synoptic circulation variations in the American South‐west. Copyright © 1986 John Wiley & Sons, Ltd"
"6602682502;","The effect of ozone photochemistry on atmospheric and surface temperature changes due to increased CO2, N2O, CH4 and volcanic aerosols in the atmosphere",1985,"10.1080/07055900.1985.9649233","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84912735165&doi=10.1080%2f07055900.1985.9649233&partnerID=40&md5=0b60db63e1ed77533d4e7f4b27df7ce4","A coupled 1‐D radiative‐convective and photochemical diffusion model is used to study the influence of ozone photochemistry on changes in the vertical temperature structure and surface climate resulting from the doubling of atmospheric CO2, N2O, CH4 and increased stratospheric aerosols owing to the El Chichón volcanic eruption. It is found when CO2 alone is doubled, that the total ozone column increases by nearly 6% and the resulting increase in the solar heating contributes a smaller temperature decrease in the stratosphere (up to 4 K near the stratopause level). When the concentration of CO2, N2O and CH4 are simultaneously doubled, the total ozone column amount increases by only 2.5% resulting in a reduced temperature recovery in the stratosphere. Additional results concerning the effect of the interaction of ozone photochemistry with the stratospheric aerosol cloud produced by the El Chichón eruption show that it leads to a reduction in stratospheric ozone, which in turn has the effect of increasing the cooling at the surface and above the cloud centre while causing a slight warming below in the lower stratosphere. © 1985 Taylor & Francis Group, LLC."
"7102577095;","Cloud optical thickness feedbacks in the CO2 climate problem",1985,"10.1016/0273-1177(85)90323-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-46549103349&doi=10.1016%2f0273-1177%2885%2990323-0&partnerID=40&md5=c82cfc339ef3de92c51aca246cd1102f","A radiative-convective equilibrium model is developed and applied to study cloud optical thickness feedbacks in the CO2 climate problem. The basic hypothesis is that in the warmer and moister CO2-rich atmosphere, cloud liquid water content will generally be larger than at present, so that cloud optical thickness will be larger too. For clouds other than thin cirrus, the result is to increase the albedo more than to increase the greenhouse effect. Thus the sign of the feedback is negative: cloud optical properties alter in such a way as to reduce the surface and tropospheric warming caused by the addition of CO2. This negative feedback can be substantial. When observational estimates of the temperature dependence of cloud liquid water content are employed in the model, the surface temperature change due to doubling CO2 is reduced by about one half. © 1985."
"7409853077;","Humidity/cloud-radiation feedback on possible climate perturbation due to fossil fuel utilization.",1985,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040854727&partnerID=40&md5=f780b29133215eb887b2527ce013f6d9","Highlights of accomplishments in climate modeling activities achieved during the period April 1984 to February 1985 are briefly summarized. Discussion is presented under the headings: uncertainties of the model calculated direct CO2 radiative effects; atmospheric CO2 and radiation balance; radiation treatment (models) ; humidity/cloud-radiation interaction; model comparison studies; and DOE state-of-the-art report.-from STAR, 23(18), 1985"
"7102875645;7003922138;","A comparison of climate model sensitivity with data from the last glacial maximum.",1985,"10.1175/1520-0469(1985)042<2643:ACOCMS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022193420&doi=10.1175%2f1520-0469%281985%29042%3c2643%3aACOCMS%3e2.0.CO%3b2&partnerID=40&md5=96ae6be4fd78eacc30c834472a405f78","An attempt has been made to use paleoclimatic data from the last glacial maximum to evaluate the sensitivity of two versions of an atmosphere/mixed-layer ocean model. Each of these models has been used to study the CO2-induced changes in climate. The models differ in their treatment of cloudiness, with one using a fixed cloud distribution and the other using a simple parameterization to predict clouds. The models also differ in the magnitude of their response to a doubling of atmospheric CO2, with the variable cloud model being nearly twice as sensitive as the fixed cloud version. it is difficult to determine which version of the model is more realistic in simulating the ice age climate for two reasons: 1) the differences between the two models are relatively small; and 2) there are substantial uncertainties in the paleoclimatic data. - from Authors"
"7103394151;","Weather.",1985,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022170719&partnerID=40&md5=81239cffafd00c632bba28b9bd601d65","Reviews the available data on weather and climate in the UK under the following chapter headings: weather and climate (dealing with the observations and the nature and form of the data); surface data (sunshine, radiation, temperature, evaporation, humidity, precipitation, wind, pressure, visibility and cloud); upper air data (radiosonde data, radar data and satellite data); improvements and future developments. Over 160 references are cited.-L.F.Musk"
"7006423931;7401456188;","Cirrus clouds. Part II: numerical experiments on the formation and maintenance of cirrus.",1985,"10.1175/1520-0469(1985)042<2682:CCPINE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022226668&doi=10.1175%2f1520-0469%281985%29042%3c2682%3aCCPINE%3e2.0.CO%3b2&partnerID=40&md5=815e5fc95b8e9d69f5383a8ebcfbd2be","The numerical cirrus cloud model of Starr and Cox is used to investigate the role of various physical processes in the formation and maintenance of cirrus. Effects due to microphysical composition, i.e., crystal habit and size distribution, are found to be quite important in determining the overall cloud water budget. Radiative processes are also shown to affect the organization and bulk properties of the cloud. Substantial differences between simulations of thin cirrus under midday and nighttime conditions are found with the cloud being less dense overall (ca.20%) but more persistently cellular during the day with all other environmental factors being the same. Cloud-scale interactions and feedbacks between dynamic, thermodynamic and radiative processes and the microphysical composition are significant and strongly modulate the properties of the simulated clouds. Inferences are drawn from these results with respect to the parameterization of cirrus in large-scale forecast or climate models. -from Authors"
"7102018821;35977548400;7402293278;","Interactive cloud formation and climatic temperature perturbations.",1985,"10.1175/1520-0469(1985)042<1969:ICFACT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022266326&doi=10.1175%2f1520-0469%281985%29042%3c1969%3aICFACT%3e2.0.CO%3b2&partnerID=40&md5=9221210a85b5fec1cf461fad6c92cc83","A one-dimensional climate model with an interactive cloud formation program is developed to investigate its effects on temperature perturbations due to various radiative forcings including doubling of CO2, a 2% increase of the solar constant and the increase of the cirrus IR emissivity. By virtue of the K-theory for turbulence transfer of sensible and latent heat fluxes, we demonstrate that the model may be described by a set of partial differential equations governing the thermodynamic energy balance, water vapor transport, vertical velocity in the cloudy region and cloud cover. In particular, we illustrate that the climatic temperature perturbation experiment may be carried out as a boundary value problem. Moreover, in order to effectively incorporate interactive cloud formation and radiative transfer programs in the model, we have designed a cloud compaction scheme based on statistical and stochastic procedures for the estimate of cloud covers, thicknesses, heights and positions for high, middle and low clouds. We show that, overall, the interactive cloud formation program reduces the sensitivity of temperature increases caused by positive radiative forcings and therefore generates a negative feedback in reference to the fixed cloud program. -from Authors"
"7202155374;","Climate Sensitivity",1985,"10.1016/S0065-2687(08)60221-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022221261&doi=10.1016%2fS0065-2687%2808%2960221-6&partnerID=40&md5=ff77a893bc57988bde45e317f2a46fb5","This chapter discusses various aspects of climate sensitivity. The term climate sensitivity refers to the possible changes in the climate system resulting from the changes in externally prescribed conditions. The energy flux at the top of the atmosphere is important to climate modelers because equilibrium global temperatures are usually much more sensitive to externally prescribed changes of energy at the top of the atmosphere than they are to model parameter or boundary condition changes that lead to internal redistributions of energy. Vertical energy redistribution by moist and dry convection processes is rapid as compared with the relaxation time for radiation balance within the troposphere. It is suggested that the largest sources of uncertainty for the sensitivity of global average temperature to external changes in tropospheric energy balance are the magnitude of the ice-snow albedo feedback processes and the magnitude and sign of cloud-radiation feedback processes. Land surfaces, through their modulation of radiant, sensible, and latent fluxes may have important feedbacks on the climate system. The statistical methods developed for the interpretation of general climate model are also elaborated. © 1985, Elsevier Inc."
"6507831288;","Physical geography - climate (Antarctic).",1985,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022190613&partnerID=40&md5=08fc8ff07fb593caef110365d5d50545","Details the main climatic parameters of the Antarctic continent and adjacent marine areas to the Convergence. Looks at surface winds, air and sea temperatures and cloud cover as well as aspects of the Ice Sheet. Then presents a summary of past climatic change and assesses the state of knowledge before briefly speculating on future trends. -R.Land"
"7202418453;","Aerosol observations for climate studies",1985,"10.1016/0273-1177(85)90302-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-46549098846&doi=10.1016%2f0273-1177%2885%2990302-3&partnerID=40&md5=be08b68a48afa0147221986b1900f6ae","The SAM II and SAGE satellite systems have provided to date more than 5 years and almost 3 years, respectively, of data on atmospheric aerosol profiles on a near-global scale. Studies with these unique data sets are developing a global aerosol climatology for the first time and have shown the existence and quantification of polar stratospheric clouds (PSC's) and tropical stratospheric cirrus. In addition, a tropospheric cirrus climatology is evolving. Since these two experiments were launched, a series of large volcanic eruptions have occurred which have greatly impacted the stratospheric aerosol loading. The aerosol layer produced by the eruption of El Chichon, for example, increased the 30 mb temperatures in the northern tropics by as much as 4°C for 6 months after the eruption. This paper will describe in detail, from a climate perspective, the evolving aerosol and cloud climatologies as a function of space and time, and show the stratospheric dynamics of volcanic injections and their enhancements on stratospheric optical depth and mass loading. © 1985."
"7007026915;","Synoptic and satellite aspects of the southwestern u.s. summer ‘monsoon’",1985,"10.1002/joc.3370050406","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022166168&doi=10.1002%2fjoc.3370050406&partnerID=40&md5=cc4aacaf1d4deb42676d42bb058fad3c","Satellite infrared imagery for three years (1980, 1981, 1982) are analysed using a colour enhancement technique to derive a cloud climatology of the southwest United States summer ‘monsoon’. Diurnally‐stratified and weekly statistics are obtained for different cloud levels and used as an index of the monsoon intensity in each year. Strong diurnal variations in cloudiness, related to surface heating, are identified for July and August, as are marked interannual differences. These regional‐scale cloud variations are found to correlate more closely with the 700mb wind direction than with the height of the 700 mb pressure surface when considered for a representative station (Winslow, Arizona). A satellite‐based definition of ‘monsoon’ best considers variations of the total cloud rather than of any individual cloud level(s). Several surface and 700 mb synoptic circulation indices are identified and related statistically to the intraseasonal cloudiness changes. The most significant association is found for the variations in latitude of the Bermuda high pressure ridge that presumably relates to changes in subsidence. However, the sign of this relationship may reverse in years when other circulation systems, notably the North Pacific anticyclone, also influence the desert Southwest. Consideration of the zonal westerly index between 45 and 65°N tends to improve the correlation between the Bermuda ridge and summer monsoon cloudiness over the region. Such cloud‐circulation studies have implications not only for climate dynamics but also for ongoing solar energy research in the American Southwest. Copyright © 1985 John Wiley & Sons, Ltd"
"24459670500;7004547261;8707123200;","Cloudiness over the Eastern Equatorial Pacific for summer 1983 from geostationary satellite data",1985,"10.1016/0273-1177(85)90321-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-46549099203&doi=10.1016%2f0273-1177%2885%2990321-7&partnerID=40&md5=5e7fe2c20f375e8a854920ddf0f18929","The extraordinary El-Nino event of 1982-83 started to fade out in the late spring of 1983. However the sea surface temperature of the Eastern Equatorial Pacific still remained warmer than normal in the following summer. To investigate the characteristics of this late transition phase of the 1982-83 El-Nino, the GOES-West satellite data of July and August of 1983 are analyzed. The outgoing longwave radiation field and the distribution of cloudiness, which was derived by using a new threshold technique, are obtained. The longwave radiation field is compared to monthly average climatic indices commonly used at the Climatic Analysis Center. The results of cloud analysis showed some interesting features during the decaying phase of the 1982-83 El-Nino. The diurnal variation of cloudiness indicates that total cloud amounts decrease from 8 GMT to 20 GMT over most of the area. This overall study demonstrates preliminary results of the International Satellite Cloud Climatology Project of the World Climate Research Program. © 1985."
[No author id available],"US Navy climatic study of the Caribbean Sea and Gulf of Mexico. Volume 1: West Caribbean Sea and Central American waters.",1985,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040856858&partnerID=40&md5=cba6ce2d956855a2b7d5cea2b3949408","This climate study consists of monthly charts and tables of: 1) clouds, 2) visibility-tables, 3) ceiling-visibility (mid range), 4) wind visibility cloudiness, 5) scalar mean wind speed, 6) wind speed less than and more than or = 34 knots, 7) wind speed 11 to 21 and 22 to 33 knots, 8) air and sea temperature 9) surface wind roses, 10) wave height-isopleths, 11) wave height-tables, and 12) surface currents (seasonal), and station climatic summaries.-from STAR, 24(9), 1986"
"7202417967;","Plan for the implementation of the world climate research programme",1985,"10.1016/0273-1177(85)90293-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141847541&doi=10.1016%2f0273-1177%2885%2990293-5&partnerID=40&md5=e61dd0c0f28910a4f37286d0fd68ab20","The objectives of the World Climate Research Programme (WCRP) are expressed in terms of increasing time scales, from several weeks to several decades. The Programme calls for substantial developments in modelling the interaction of the global atmosphere with the ocean, land surface and sea-ice, as well as improved computations of radiation transfer in the presence of clouds, aerosols and absorbing gases. These developments require a large variety of space as well as surface based observations, and especially, additional efforts for systematic processing of available data to produce consistent records of significant climatological variables. The forthcoming development of a new generation of ocean observing satellites will be an essential component of the WCRP, as they will provide the data base for the large-scale oceanographic projects, the World Ocewan Circulation Experiment (WOCE) and the study of thew Tropical Ocean and the Global Atmosphere (TOGA). © 1985."
[No author id available],"'NUCLEAR WINTER'. A DIAGNOSIS OF ATMOSPHERIC GENERAL CIRCULATION MODEL SIMULATIONS.",1985,"10.1029/JD090iD03p05615","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022076925&doi=10.1029%2fJD090iD03p05615&partnerID=40&md5=5f1471fd463d8fd98108938cadf20193","The paper investigates the adiabatic and diabatic thermal balance of an atmospheric general circulation model (GCM) under two conditions: the control case, representing today's atmosphere, and a 'nuclear winter' scenario in which virtually all sunlight in northern hemisphere mid-latitudes is absorbed in the upper troposphere by prescribed dense smoke clouds in moisture and cloudiness simulated by the model are also examined. The object is to examine the reliability of existing simulations of the climate response to assumed dense, widespread, high-altitude smoke and to identify improvements needed in model parameterizations. Refs."
"7103245410;","The terminal Cretaceous event: Circumterrestrial rings of tektite glass particles?",1985,"10.1016/0195-6671(85)90049-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022225650&doi=10.1016%2f0195-6671%2885%2990049-7&partnerID=40&md5=c7fd30a5424e29435621ac16af7f11ad","It is proposed to regard the terminal Cretaceous event as similar to the radiolarian extinction event in the late Eocene: the result of a volcanic eruption or series of eruptions on the moon. Some glassy ash, lapilli and blocks from these eruptions fell to the earth; some, in geocentric orbit, formed clouds around the earth. In accordance with current theory, it is found that the clouds in orbit would evolve into sets of rings, which would last a few hundred thousand to a few million years, and would perturb the climate of the earth. One such eruption apparently included iridium-bearing material, perhaps from the deep interior of the moon. The hypothesis permits a reconciliation between the evidence for the catastrophic intervention of extra-terrestrial masses in the earth environment, and the evidence for gradual (though rapid) change of flora and fauna at the Cretaceous/Tertiary boundary. The formation of the E-ring of Saturn by ejecta from the Saturnian satellite Enceladus may have been analogous. The theory might be tested by studies of diurnal layering in molluscan shells. © 1985."
"7601452199;7406327123;","Expectancy of cloudless photographic days in the contiguous United States.",1985,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022265062&partnerID=40&md5=243510940b0a36bac456cd79f94a4413","The Sette Weather Chart was produced in 1939 using data collected from the years 1900 to 1936 to predict cloudless photographic days in the United States. Inadvertent climate modifications that have taken place since this time period makes this chart obsolete. Using current National Weather Service records from the period 1950 to 1982, the number of days having 0.1 cloud cover or less are tabulated. A new chart is produced that can predict cloudless photographic days based on current data. Forty-five cities are common both to Sette's original study and the current study. Forty-four out of the forty-five cities have had their annual monthly average of cloudless photographic days decrease between the time periods 1900-1936 and 1950-1982. Fort Worth, Texas is the only city that had its monthly average photographic days increase between the time periods studied. -Authors"
"6508186078;7006689582;","RELATIVE CONTRIBUTION OF CLIMATE VARIABLES TO THE FORMATION OF THE FLUX OF DEPARTING HEAT RADIATION.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021660059&partnerID=40&md5=7cd67975f36eb06e8440b66037627537","Based on zonal mean monthly satellite and surface data, the relative contribution of the major climate variables to the formation of the flux of departing heat radiation F is determined in the annual course for the Northern Hemisphere. For the hemisphere as a whole the greatest contribution to the variation of F in the annual course is made by the variations of the temperature field, followed by the humidity field and the cloud cover (amount of clouds). The temperature field plays the most substantial role in the formation of the F flux at extratropical latitudes. At tropical latitude the contribution of various climate variables to the variations of the F flux is comparable."
"7202673976;","On the application of meteorological satellite imagery for monitoring the environment.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021644205&partnerID=40&md5=a9f27c18826a44a8807be3fab398e8e8","Meteorological satellites now routinely monitor the Earth and provide measurements of the atmosphere, ocean and land surface which are used for studies of weather and climate. A review is given of our current knowledge, with particular emphasis directed towards remote sensing of clouds, atmospheric energetics, mesoscale meteorology and radiation budget. -Author"
"57207507371;","RADIATION EFFECTS OF PRODUCTS OF THE ERUPTION OF THE EL CHICHON VOLCANO.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021625695&partnerID=40&md5=15884e5555eed8e43beed0fe59de1dea","Briefly reviewed are the preliminary results of studies of the cloud of eruption products of the El Chichon volcano in southern Mexico in spring 1982 and its possible effects on the climate."
"7005533663;6603835471;","Possible climatic impacts of land cover transformations, with particular emphasis on tropical deforestation",1984,"10.1007/BF00142475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021569488&doi=10.1007%2fBF00142475&partnerID=40&md5=e5c6e7f2810d790edf02e6976453d731","The climatic impact of albedo changes associated with land-surface alterations has been examined. The total surface global albedo change resulting from major land-cover transformations (i.e. deforestation, desertification, irrigation, dam-building, urbanization) has been recalculated, modifying the estimates of Sagan et al., (1979). Tropical deforestation (11.1 million ha yr-1, or 0.6% yr-1, Lanly, 1982) ranks as a major cause of albedo change, although uncertainties in the areal extent of desertification could conceivably render this latter process of similar significance. The maximum total global albedo change over the last 30 yr for the various processes lies between 0.000 33 and 0.000 64, corresponding to a global temperature decrease of between 0.06 K and 0.09 K (scaled from the 1-D radiative convective model of Hansen et al., 1981), which falls well below the interannual and longer period variability. An upper bound to the impact of tropical deforestation was obtained by concentrating all vegetation change into a single region. The magnitude of this modification is equivalent to 35-50 yr of global deforestation at the current rate, but centered on the Brazilian Amazon. The climatic consequences of such tropical deforestation were simulated, using the GISS GCM (Hansen et al., 1983). In the simulation, a total area of 4.94 × 106 km2 of tropical moist forest was removed and replaced by a grass/crop cover. Although surface albedo increased from 0.11 to 0.19, the effect upon surface temperature was negligible. However, other climate parameters were altered. Rainfall decreased by 0.5-0.7 mm day-1 and both evapotranspiration and total cloud cover were reduced. The absence of a temperature decrease in spite of the increased surface albedo arises because the reduction in evapotranspiration has offset the effects of radiative cooling. The decrease in cloud cover also counteracts the increase in surface albedo. These locally significant changes had no major impact on regional (Hadley or Walker cells) or the global circulation patterns. We conclude that the albedo changes induced by current levels of tropical deforestation appear to have a negligibly small effect on the global climate. © 1984 D. Reidel Publishing Company."
"7007067997;56744278700;7201947066;","Graphitic carbon content of aerosols, clouds and snow, and its climatic implications",1984,"10.1016/0048-9697(84)90255-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021282670&doi=10.1016%2f0048-9697%2884%2990255-9&partnerID=40&md5=95456f23c7e49c2eeef6bd52f87f6d0d","Effect of graphitic carbon on radiative characteristics of aerosols, clouds and snow is investigated using a random internal mixture model in which most particles are randomly distributed throughout the volume of individual aerosols, cloud drops and snow grains. It is found that the specific absorption of carbon in aerosols, drops and snow grains is increased several times over the specific absorption of carbon in air. This leads to a decrease in the albedo of aerosols, clouds and snow, suggesting that graphitic carbon could exert a nonnegligible influence on regional and global climate. © 1984."
"7004160106;7406470475;","Ensemble formulation of surface fluxes and improvement in evapotranspiration and cloud parameterizations in a GCM",1984,"10.1007/BF00206830","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021554348&doi=10.1007%2fBF00206830&partnerID=40&md5=df655f99c3656d56a08c7b1ff45caacf","The influence of some simple modifications to the physical parameterizations in the current GLAS climate GCM is examined. The aim of these modifications was to eliminate strong occasional bursts of 2 - δt oscillations in the PBL fluxes. The PBL of the current GLAS climate model was modified by invoking concepts of ensemble averaging of PBL eddies in a grid cell of the GCM. This resulted in smoothly varying bulk aerodynamic friction and heat transport coefficients. An arbitrary function to account for diffusion of moisture from stomatal cavities found in vegetation was also incorporated. Simultaneously some modifications to the cloud parameterizations were made. Two integrations, one with the old model and the other with the modified model, were made to simulate 47 days, starting from the NMC analysis for June 15, 1979. Their comparisons showed that the surface fluxes and cloudiness in the modified model simulations are far better. The planetary albedo in the modified model is also realistic. However, some weaknesses still persist, including an ITCZ (Inter-tropical convergence zone) that is too far northward in Sahelian Africa, polar regions that are too cold, and a rather strong ITCZ. It is pointed out that these weaknesses are primarily caused by model deficiencies, e.g., the cloud parameterization and the uniformly prescribed land surface roughness height. In another simulation with the modified model using a realistic value of surface roughness for deserts, the precipitation in the Sahara Desert reduced significantly, which effectively pushed the ITCZ southward to a more realistic location as compared to observations. © 1984 D. Reidel Publishing Company."
"7005533663;7005242501;7102581300;","We've looked at clouds from all sides now.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021596174&partnerID=40&md5=17978b09a6356a19f68248b207992366","The requirement for global cloud information for use in climate modelling is recognized as one of the outstanding problems to be solved in current climate research. Model predicted and observed clouds differ fundamentally and modes of observation result in yet further disparity in cloud cover information. We examine the advantages and disadvantages of all systems laying particular emphasis on the importance and difficulty of incorporating surface as well as satellite observations into a global cloud archive. It is difficult, perhaps impossible, to envisage an operational system that could provide all the aspects of cloud information which climate modellers require.-from Authors"
"7201914101;7004325649;","Stratocumulus cloud field reflected fluxes: the effect of cloud shape.",1984,"10.1175/1520-0469(1984)041<3085:SCFRFT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021639145&doi=10.1175%2f1520-0469%281984%29041%3c3085%3aSCFRFT%3e2.0.CO%3b2&partnerID=40&md5=cf133329558180359a0916450f31340d","Reflected fluxes are calculated for stratocumulus cloud fields as a function of sky cover, cloud aspect ratio, and cloud shape. Cloud liquid water volume is held invariant as cloud shape is varied so that the results can be utilized more effectively by general circulation models and climate models. -from Authors"
"56283400100;55888426900;","The importance of cloud-radiation interaction for the simulation of climate.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021562501&partnerID=40&md5=6431913f0d98f342d1faa5c0056404a1","The LMD GCM is used to investigate the importance of cloud-radiation interaction for the simulation of climate. The results suggest that cloud radiation interaction might play an important role to determine the longitudinal patterns of the atmosphere, and also to determine the variability of the summer hemisphere.-from Authors"
"57198660821;","Clouds and climate - a subtle connection ( Australia).",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021547963&partnerID=40&md5=2da0bff3d77cce56b5ac63d0218f341a","Researchers in the CSIRO Division of Atmospheric Research and the Australian Numerical Meteorology Research Centre are trying to clarify the part that clouds play in controlling climate. The work is important for answering questions about the stabilty of climate, particularly in evaluating the influence of increased carbon dioxide levels or possible lowered ozone concentrations.-after Author"
"7102577095;57198369060;","Cloud optical thickness feedbacks in the CO2 climate problem.",1984,"10.1029/JD089iD06p09668","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021641125&doi=10.1029%2fJD089iD06p09668&partnerID=40&md5=f8a0113751021717f0f048ee78a20949","A radiative-convective equilibrium model is developed and applied to study cloud optical thickness feedbacks in the CO2 climate problem. The basic hypothesis is that in the warmer and moister CO2-rich atmosphere, cloud liquid water content will generally be larger too. For clouds other than thin cirrus the result is to increase the albedo more than to increase the greenhouse effect.-from Authors"
"7102581300;7005533663;","A new global oceanic cloud climatology for climate modelling.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021557710&partnerID=40&md5=7e183944bab7d14814f7944cabcdffbc","In this paper a new global oceanic cloud climatology is derived. The variety of different global cloud distributions are illustrated with a brief review of the global cloud climatologies currently available. A predictive relationship between NOAA system albedo data and 3D-nephanalysis cloud amount data has been used to derive a new oceanic global cloud climatology.-from Authors"
"7005793728;7003991093;","An energy balance climate model with cloud feedbacks.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021598285&partnerID=40&md5=5e2dddec13c7049a06908d650f43024a","A simple two-level global climate model based on the energy balance of the atmosphere and surface is described. Several model integrations are described. It is found that cloudiness is generally constant with changing temperature in low latitudes. In high latitudes cloudiness increases with increasing temperature but because of compensating effects on the thermal and solar radiation, the cloud feedback effect on the radiation field is small. The net global feedback by the cloud field is negative but small.-from Authors"
"7402516739;","Atmospheric effects of nuclear war",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021639113&partnerID=40&md5=f7ab574356f58c17ab4effa63e7aa8c1",[No abstract available]
"7005793728;7003991093;57198369060;","Cloud/climate sensitivity experiments.",1984,"10.1029/gm029p0092","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021535240&doi=10.1029%2fgm029p0092&partnerID=40&md5=c13c0528d433a07090f1028ebe44275b","A study of the relationships between large-scale cloud fields and large-scale circulation patterns is presented. The basic tool is a multi-level numerical model comprising conservation equations for temperature, water vapor and cloud water and appropriate parameterizations for evaporation, condensation, precipitation and radiative feedbacks. It is shown that cloud cover increases with decreased eddy vertical velocity, decreased horizontal advection, decreased atmospheric temperature, increased surface temperature, and decreased precipitation efficiency. -from Authors"
"7003833060;","Tropospheric science.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021562558&partnerID=40&md5=a033921d76caea9149603c63e9e5d832","Nowcasting, current weather forecasting, extended range forecasting and climate prediction are discussed with an emphasis on the observational requirements of climate prediction. Integrated hydrologic cycle measurements, cloud parameter characterization, air sea interaction measurements, tropical winds, and tropospheric gaseous species measurements are discussed.-from STAR, 22(20), 1984"
"7004942632;7005533663;7202840464;","Albedo-climate feedback: the importance of cloud and cryosphere variability.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021538827&partnerID=40&md5=11467c55c8167ac0a927a9f6e0001e76","One of the pre-eminent processes in theories of climate change is the ice-albedo feedback effect. The complexity of albedo parameterizations in energy balance climate models has increased with time. Earlier parameterizations have been replaced by empirical formulations heavily dependent on satellite data. Here, we question the interpretation of these satellite data.-from Authors"
"57203400519;57000608200;","Solar reflection from interacting and shadowing cloud elements.",1984,"10.1029/JD089iD05p07179","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021640157&doi=10.1029%2fJD089iD05p07179&partnerID=40&md5=572d938c7504aa6309008d686de2a137","The parameterizatin of solar reflection from clouds used in climate and general circulation models is based on radiative transfer theory appropriate for plane parallel clouds. We have attempted to relate the reflection from a broken cloud field to that from a plane parallel cloud of the same optical properties by using Monte Carlo simulations for a very simple model of an array of regularly spaced, infinitely long bar clouds. Model computations for reflection from an array of randomly distributed identical cylinders are also presented as an example of a possible application of this technique.-from Authors"
"57156235100;7006784145;7004499360;","Carbon dioxide concentration doubling and solar constant changing: the role of clouds in influencing the climatic response.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021569755&partnerID=40&md5=8bca00caa5573b59e4b829f49d22a0ad","The influence of cloud amount-temperature and ice-albedo feedbacks on the climatic sensitivity when they are considered separately or together, is studied using a one-dimensional, radiative-convective globally averaged climatic model.-from Authors"
"57202520105;57203376957;","Climate processes and climate sensitivity.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040858129&partnerID=40&md5=0410061ad83dfaac2eb7716ba3504191","The c30 papers in the book result from a symposium in 1982 and bring together the work of modellers and others involved in the analysis of observational data. The approach considers climatic variations and processes (especially feedback processes) on a broad range of time scales. The arrangement is in sections: atmosphere and ocean dynamics; hydrologic cycle and clouds; albedo and radiation processes; cryospheric processes; ice cores and glacial history; ocean chemistry. Papers are abstracted separately. -from Editors"
"6602199552;6506634570;55547129175;","Convective rain rates and their evolution during storms in a semiarid climate.",1984,"10.1175/1520-0493(1984)112<1602:CRRATE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021535021&doi=10.1175%2f1520-0493%281984%29112%3c1602%3aCRRATE%3e2.0.CO%3b2&partnerID=40&md5=74901153d0a15a58a327e7c83fe3be81","Rain rates and their evolution during summertime convective storms were analyzed for the semiarid climate of the northern High Plains. Radar data from a total of 750 radar echo clusters from the 1980 and 1981 summer cloud seeding operations of the North Dakota Cloud Modification Project (NDCMP) were used. The analysis suggests that the average rain rate R among storms is, in a first approximation, independent of the total rain volume if the entire storm duration is considered in the averaging process. -from Authors"
"57209916387;","Theoretical development of Monte Carlo codes for modeling cumulus cloud fields.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040854883&partnerID=40&md5=6eaf62e472cac93b8562dedad71b1a96","Reflected fluxes are calculated for stratocumulus cloud fields as a function of skycover, cloud aspect ratio, and cloud shape. Cloud liquid water volume is held invariant as cloud shape is varied so that the results can be utilized more effectively by general circulation models and climate models. On the basis of required accuracy in the Earth Radiation Budget Experiment program, an order of magnitude value of 10W/sq m is used to estimate significant differences between plane parallel and broken cloudiness. This limit is exceeded for cloud covers between 10% and 90%, indicating that plane paralel calculations are not satisfactory at most values of cloud cover. The choice of cloud shape also leads to large differences in reflected fluxes. These differences are traced to the anisotropic intensity pattern out the cloud sides, to the size and shape of the holes between clouds, and to variations in cloud area as viewed from the solar direction. An empirical relationship for effective cloud cover is given at solar zenith angle of theta = 60o. This relationship allows for the relatively accurate (delta F = 10-15 W/sq m) computation of broken cloud field reflected fluxes from plane parallel calculations.-from STAR, 23(2), 1985"
"56172183000;","Climate ( Sahara).",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021535038&partnerID=40&md5=0d648639b787ad097aa882224aee1500","The climate of the Sahara is related, in general terms, to a model of the general circulation of the atmosphere, stressing the significance of the desert's location astride the Tropic of Cancer. Details are then provided of surface pressure, winds and air masses; global radiation and sunshine; air temperatures; atmospheric humidity and evaporation; cloud and precipitation; and wind and visibility. Recent climatic change is noted, and possibilities of man-induced alteration of the climate are dismissed. -P.J.Jarvis"
"7102389805;7202899330;","Cloud- radiation interaction and the climate problem.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021581683&partnerID=40&md5=7e4debe8f8075de352e265f83d988fb4","Observational evidence of the timescales over which radiation-cloud interaction occurs is presented. Variations, shown in terms of net outgoing longwave radiation, are found to exist with almost equal magnitude on timescales ranging from synoptic to interannual. The association of these variations with changes in boundary forcing (eg equatorial Pacific Ocean warmings) and subsequent changes in heating distributions is discussed. -from Authors"
"7004942632;7005533663;7004034323;","The influence of the spectral response of satellite sensors on estimates of broadband albedo",1984,"10.1002/qj.49711046624","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983942497&doi=10.1002%2fqj.49711046624&partnerID=40&md5=ed774d73d6eb96611a6f16a8a248c899","The radiative impact of cloudiness variations on climate depends on the relative magnitudes of changes in the planetary albedo and the outgoing longwave radiation. R. D. Cess and co‐workers showed in 1982 that the calculated direction of the cloud‐climate feedback (i.e. whether the earth‐atmosphere system warms or cools with changing cloud amount) depended on the satellite data sets used in their analysis. It was suggested that the different spectral resolutions of the satellite sensors might be responsible. This note examines that suggestion. It is shown that the change in planetary albedo measured by the narrow band scanning radiometers on board NOAAs 2 to 5 as a result of cloudiness variation can be an overestimate of the actual change by a factor of up to 1.38 at low latitudes. The overestimate is not sufficient to explain completely the differences amongst the satellite data. Nevertheless, the results indicate that satellite spectral response must be carefully considered if the strength (and possibly even the sign) of the cloud‐climate feedback is to be correctly assessed from narrow band satellite data. Over snow‐covered surfaces it is shown that the NOAA data may underestimate the effect of cloud cover changes by over 70%, and overestimate the planetary albedo by over 0.2. Copyright © 1984 Royal Meteorological Society"
"55665464100;7005533663;","Effects of cloudiness on the high-latitude surface radiation budget.",1984,"10.1175/1520-0493(1984)112<1017:EOCOTH>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021547715&doi=10.1175%2f1520-0493%281984%29112%3c1017%3aEOCOTH%3e2.0.CO%3b2&partnerID=40&md5=b9c306cf9695b5ce381040e4659bd875","Ten years of hourly data on radiation, cloud and temperature collected at Resolute, Canada (75oN) show that with respect to clear skies: clouds of all types, heights and extents heat the surface when it is snow-covered; low clouds certainly cool and high clouds probably warm the surface when it is snow-free; the transition to scattered then broken then complete cloud cover is accompanied, at least over snow-covered surfaces, by mostly monotonic changes in most radiation-balance quantities, including net radiation; cirriform overcasts alter the surface radiation climate by relatively strong greenhouse heating offset by relatively modest attenuation of solar radiation, and our empirical results help to substantiate recent model calculations of the cirrus greenhouse effect.-from Authors"
"7102018821;57198199168;","Recent progress in atmospheric radiation.",1984,"10.1175/1520-0477-65.5.475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021564275&doi=10.1175%2f1520-0477-65.5.475&partnerID=40&md5=9f39fb340615911df6f6679f6a1e6d2a","This report contains summaries and highlights of the papers presented at the Fifth Conference on Atmospheric Radiation. Papers spanning the subjects of satellite remote sensing, interactions of radiation and general circulation, effects of clouds and aerosols on climate, radiation budget studies from satellites, some aspects of radiative transfer and radiation measurements, and solar energy applications were presented.-from Authors"
[No author id available],"Report of the third session of the International Working Group on Data Management for the International Satellite Cloud Climatology Project ( ISCCP).",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040845634&partnerID=40&md5=fddfdd4c683e958c77c536f0f63dc013","Algorithms for the modeling of the radiative properties of clouds are examined. The coordination of regional and global data collection centers is also investigated. A comparison is made between satellite data and modeled radiance information to improve the accuracy of the climate models. Emphasis is also placed on data management and information dissemination. -from STAR, 23(2), 1985"
"6602199552;55547129170;6601955569;","Boundary layer- cloud interactions as potential storm predictors.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021557033&partnerID=40&md5=2cc1076bb1fb9a6d95ed655dcb831377","Data from a surface mesonet in the semi-arid climate of southeastern Montana are used to explore interactive mechanisms between storms and their environment. An improved formula in calculating the total moisture inflow into the cloud in which the ACTI plays an important role is suggested. A semi-diurnal cycle in the variance of the net divergence field over the network was revealed in 'dry' days.-from Authors"
"7202145115;7003545639;7006432091;","Some implications of the mesoscale circulations in tropical cloud clusters for large-scale dynamics and climate ( Walker circulation).",1984,"10.1175/1520-0469(1984)041<0113:SIOTMC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021174331&doi=10.1175%2f1520-0469%281984%29041%3c0113%3aSIOTMC%3e2.0.CO%3b2&partnerID=40&md5=d0ede6b9b9ef0128d77ae5523e4b6038","Recent calculations suggest that mature cloud clusters produce a vertical distribution of diabatic heating with a sharp maximum near 400 mb and very weak heating below 600 mb. It is demonstrated that when such a vertical distribution of heating is applied to a linear steady-state model it results in simulated tropical east-west circulations which are in much better agreement with observations than those which are produced with a more conventional heating profile. In particular, the mature cloud cluster heating profile produces a Walker Circulation with its centers at the observed altitudes and with the observed westward tilt with height. -from Authors"
"7004034323;","The cloudy marine boundary layer in the Meteorological Office climate model, appendix I ( UK).",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040845308&partnerID=40&md5=c120f7d759068ae720edcc7343c445d1","Some problems experienced in implementing a cloud-precipitation scheme and the approach used to find solutions are described. The general problem of the proper representation of the cloudy marine boundary layer in numerical models is addressed.-from STAR, 22(18), 1984"
"7003830856;6506382943;7004853630;","An assessment of the impact of pollution on global cloud albedo",1984,"10.1111/j.1600-0889.1984.tb00254.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989135017&doi=10.1111%2fj.1600-0889.1984.tb00254.x&partnerID=40&md5=49b498ac0f82cf96bfddec1132ee9414","Increased pollution leads to increasing particulate concentrations. Since some particles nucleate drop formation, clouds will contain, with increasing pollution, more drops per unit volume, and hence will tend to be optically thicker and more reflecting. An opposite effect is also present, in that increasing absorption also attends increasing pollution. Measurements suggest that the former (brightening) effect is the dominant one for global climate and that the climatic effect is quite comparable to that of increased carbon dioxide, and acts in the opposite direction. 1984 Blackwell Munksgaard"
"7004423756;7004335383;7005508323;7005293830;","Remote sensing of weather and climate parameters from HIRS2/MSU on Tiros-N.",1984,"10.1029/JD089iD03p04677","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021644033&doi=10.1029%2fJD089iD03p04677&partnerID=40&md5=ea3fdd4b956cf909d7d6569d45a73405","At the Goddard Laboratory for Atmospheric Sciences (GLAS) a physically based satellite sounding retrieval system has been developed involving the simultaneous analysis of HIRS2 and MSU sounding data for determining atmospheric and surface conditions which are consistent with the observed radiances. In addition to determining accurate atmospheric temperature profiles even in the presence of cloud contamination, the system provides global estimates of day and night sea or land surface temperatures, snow and ice cover, and parameters related to cloud cover.-from Authors"
"26430935600;","Ocean surface wind stress.",1984,"10.1007/978-94-009-6421-1_8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021553489&doi=10.1007%2f978-94-009-6421-1_8&partnerID=40&md5=86996e8c9005af5bf534342f09512674","There is an urgent need in physical oceanography, meteorology, marine operations and climate research for improved surface wind and wind stress information. Much can be done to improve our knowledge through better collection of existing observations, deployment of properly instrumented drifting buoys, better calibration and collection of cloud motion vectors, increased scrutiny and development of analysis/forecast methods of surface data assimilation and more widespread direct measurement of surface stress. But the space and time sampling constraints on such techniques will inevitably limit the improvement to less than is desirable or needed. -from Author"
"6602682502;27267529400;","The possible effects of El Chichon eruption on atmospheric thermal and chemical structure and surface climate.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021534308&partnerID=40&md5=85cff3fee20c6004401f26f425f1c092","It is suggested that the injection of sulfur oxides and ash into the stratosphere from 1982 El Chichon eruption, would alter the radiative photochemical balance of the earth's atmosphere which in turn leads to the changes in the vertical temperature and chemical structure of the atmosphere and surface climate. In this study 1D radiative-convective-photochemical model is used to compute the thermal and chemical response of the atmosphere and the surface climate to enhanced stratospheric aerosol concentration resulting from the El Chichon eruption. The recent observational data on aerosol optical thickness and optical properties obtained from the global monitoring of the El Chichon cloud has been used as input to model integration. The model allows variable aerosol concentrations and optical properties in time during the life cycle of the volcanic cloud. The preliminary results show that during the first year after the eruption, the global average surface temperature decreases by about 0.9oC while causing significant warming in the lower stratosphere (up to 5oC). The atmosphere and the surface will reach their background temperature values within roughly 3-4yr after the eruption. Also discussed are the implications of El Chichon eruption to stratospheric ozone photochemical cycle.-Authors"
"56133764000;7005036098;","The climate of northern Australia.",1984,"10.1016/b978-0-12-545080-5.50009-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021563621&doi=10.1016%2fb978-0-12-545080-5.50009-9&partnerID=40&md5=65736c3e1cad9b6e6699f420bab035c2","Having reviewed the significance of a range of climatic controls, the authors look in turn at the phenomena of thunderstorms and hail, frosts, sunshine and radiation, cloud and evaporation, and then review the significance of such major natural hazards as tropical cyclones, floods, drought and bushfires. -J.Sheail"
"57212825598;57198182468;57217373345;","The sensitivity of a general circulation model to Saharan dust heating.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021554652&partnerID=40&md5=48331bedcf15e2ba1a3c4aa74040f0b3","During the northern summer sporadic outbreaks of wind borne Saharan dust are carried out over the Atlantic by the tropical easterlies. Optical depths due to the dust can reach 3 near the African coast, and the dust cloud can be detected as far west as the Caribbean Sea. In order to obtain insight into the possible effects of Saharan dust on the weather and climate of North Africa and the tropical Atlantic Ocean, simulation experiments have been performed with the Climate Model of the Goddard Laboratory for Atmospheric Sciences.-from STAR, 22(12), 1984"
"7202840464;7005533663;7004942632;","Climate sensitivity and the marginal cryosphere.",1984,"10.1029/gm029p0221","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021552465&doi=10.1029%2fgm029p0221&partnerID=40&md5=79b4745211a6c898ad5533efb620127a","There is a significant dearth of information on high-latitude cloudiness and the surface properties of the seasonal cryosphere, and on the degree of association between them. Following a survey of available data, some new observational material is presented on cloud conditions in the vicinity of snow cover and sea ice margins, using both 3-D Nephanalysis data and DMSP imagery. -from Authors"
"7403233451;57206408063;6701413579;","Global climatic consequences of nuclear war: Simulations with three dimensional models",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021282909&partnerID=40&md5=6a315bd0b4aa56f8ac701f20387c1118","The pollution of the atmosphere by massive amounts of smoke and dust following a large scale nuclear exchange could greatly decrease sunlight reaching the earth's surface in Northern Hemisphere midlatitudes, and perhaps globally. Simulations with two different three-dimensional global climate models show subfreezing land surface temperatures underlying the hypothesized dense Northern Hemisphere smoke cloud, particularly in continental interiors. The accompanying profound changes in atmospheric circulation would tend to transport the smoke upwards and towards the tropics and Southern Hemisphere, possibly bringing those areas into the severe climatic disruption spawned by a Northern Hemisphere war. Refs."
"6603746465;55457774600;","The past, present, and anticipated future contributions of geosynchronous satellites to short range prediction ( weather, climate).",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021606207&partnerID=40&md5=7053b2dda3571e6d311e82d4b70218f1","To improve the short range prediction of convective and mesoscale phenomena, geosynchronous satellites can measure cloud parameters, surface temperature, and temperature and moisture profiles and gradients (in clear and partly cloudy areas) with temporal resolutions of minutes, and spatial scales ranging from 1 km (for clouds) to tens of kilometers (temperature and moisture profiles). Further improvements can be made with microwave sounding (temperature and moisture profiles in cloudy areas) and imaging (precipitation), higher spectral resolution infrared sounding to yield about a 50% better vertical resolution for temperature and moisture profiles, and very high resolution imaging (infrared resolution of 1 km, visible resolution of 200m) for accurate convection monitoring and other parameter improvements.-Authors"
"6602460195;","The influence of weather variability on evaporation leeward of A medium porous barrier",1984,"10.1002/joc.3370040503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021569543&doi=10.1002%2fjoc.3370040503&partnerID=40&md5=48972356509c003948626b9a48cc787d","Black porous disc atmometers were used to measure daily evaporation (E) at a distance of 4H (where H is barrier height) leeward of a medium porous hedge and in the open. The modification of E at the sheltered position was defined, in relative terms, as the percentage of the sheltered E to that in the open (relative E) and in absolute terms as the difference between the open and sheltered E totals. Although relative E was found to vary as a linear function of the relative wind (RW), E differences varied also with the meteorological conditions influencing the ‘evaporative climate’, identified here by the weather parameters: cloud cover, relative humidity and wind speed. For a particular value of relative E, the E differences were greatest on days with no cloud, low humidity and moderate wind speed and least on cloudy, humid days with low wind speed. Copyright © 1984 John Wiley & Sons, Ltd"
"7003345391;7006346923;6701442892;","A seasonal model of the Saturnian upper troposphere: Comparison with Voyager infrared measurements",1984,"10.1016/0019-1035(84)90189-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0040272651&doi=10.1016%2f0019-1035%2884%2990189-1&partnerID=40&md5=6e97e72b019636baf91e02c1cc27d042","An extension of the seasonal climate model of R. D. Cess and J. Caldwell (1979, Icarus, 38, 349-357) to Saturn's upper troposphere is presented. The ring-modulated latitudinal dependence of the insolation, the ring thermal emission, the oblateness of the planet, the orbit eccentricity, and the latitudinal variation of the internal heat flux are taken into account. Calculations agree closely with the temperature-latitude profiles retrieved from Voyager IRIS measurements at atmospheric levels located above the 0.2-bar pressure level; they reproduce the observed large-scale hemispheric asymmetry which is then shown to result from the seasonally variable insolation. Aerosol absorption is found to be the dominant source of atmospheric solar heating in the troposphere and the model suggests an aerosol mean unit optical depth around the 0.25-bar level in the equatorial region and around the 0.35-bar level at other latitudes. The model fails to predict the retrieved temperature-latitude profiles below the 0.3-bar level. This discrepancy is attributed to the existence of clouds at these levels which are responsible for an additional far-infrared opacity not taken into account in the temperature retrieval. The cloud-top altitude would be about 0.3 bar except in the 20 to 40°N region where these clouds would be confined below the 0.6-bar level. The poor correlation between infrared measurements and visible images is discussed and a possible model of Saturn's cloud structure is proposed. © 1984."
"7409671103;","An Earth longwave radiation climate model.",1984,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040855724&partnerID=40&md5=770446907a98ba3b8ed3d55b1fd0dee8","An Earth outgoing longwave radiation (OLWR) climate model was constructed for radiation budget study. Required information is provided by an empirical 100 mb water vapor mixing ratio equation of the mixing ratio interpolation scheme. Cloud top temperature is adjusted so that the calculation would agree with NOAA scanning radiometer measurements. Both clear sky and cloudy sky cases are calculated and discussed for global average, zonal average and world-wide distributed cases. The results agree well with the satellite observations. The clear sky case shows that the OLWR field is highly modulated by water vapor, especially in the tropics. The strongest longitudinal variation occurs in the tropics. This variation can be mostly explained by the strong water vapor gradient. Although in the zonal average case the tropics have a minimum in OLWR, the minimum is essentially contributed by a few very low flux regions, such as the Amazon, Indonesian and the Congo.-from STAR, 23(15), 1985"
"7005965757;7006518289;","Seasonal cycle experiment on the climate sensitivity due to a doubling of CO2 with an atmospheric general circulation model coupled to a simple mixed-layer ocean model.",1984,"10.1029/JD089iD06p09475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021640573&doi=10.1029%2fJD089iD06p09475&partnerID=40&md5=296a6232e3130f9e8dff291bb8470901","A simple slab ocean of 50 m depth, which allows for seasonal ocean heat storage but no ocean heat transport, is coupled to a global spectral general circulation model with global domain, realistic geography, and computed clouds. Globally averaged, the annual mean surface air temperature increase computed over the last 3 years of an integration with a full annual cycle for 2 x CO2 compared to the control for 1 x CO2 is 3.5oC. Zonal mean air temperature differences indicate stratospheric cooling and tropospheric warming as seen in other CO2 modeling studies. Greatest increases of surface air temperature in the 2 x CO2 case, compared to the control, occur near the sea ice margins.-from Authors"
"7003466102;6701808711;7005412286;","Satellite measurements of sea-surface temperature for climate research.",1984,"10.1007/978-94-009-6421-1_6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021578306&doi=10.1007%2f978-94-009-6421-1_6&partnerID=40&md5=f913376d97b7e9924a9ab0860424443c","Factors determining the accuracy with which the sea surface temperature can be measured from space using infrared radiometers are discussed. These include the clear atmosphere radiative effects, contamination of the signal by clouds in the field of view, and sun glitter at the 'atmospheric window'. The effects of near surface vertical temperature gradients caused by surface heat loss (the skin effect) and by solar heating (the diurnal thermocline) are also discussed. A review of present measurement capabilities is made and a brief description is given of the Along Track Scanning Radiometer (ATSR), which will fly on the European satellite ERS-1 to provide accurate measurements of sea surface temperature using a multi-angle, multichannel technique to overcome the effects of the clear atmosphere.-Authors"
"7004065389;7003385154;6602739399;","The 1982 eruptions of El Chichón Volcano (Chiapas, Mexico): Character of the eruptions, ash-fall deposits, and gasphase",1984,"10.1016/0377-0273(84)90056-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021283184&doi=10.1016%2f0377-0273%2884%2990056-8&partnerID=40&md5=4d8a506d2b3996284b96f8a0cdf037ee","Three modest plinian eruptions occurred at El Chichón Volcano during March-April 1982, producing an ENE-trending lobe of ash covering 45,000 km2 within the 1 mm isopach, and ash-flow and surge deposits in proximal areas. The total volume of juvenile magma erupted was 0.38 km3 DRE. Ash-fall samples show polymodal grain-size distributions with median grain size decreasing away from the volcano. The ash-fall deposit is relatively fine-grained; more than 80% of the erupted material is in the sub-mm fraction. Larger ash particles were commonly armored with fines, and fines clustered together to form tightly cemented aggregates. Both processes contributed to efficient and rapid removal of fines from the eruption plume. The bulk chemical composition of ash samples can be closely modeled by fall-out fractionation of glass and minerals from the eruptive plume combined with adsorption of sulfur, sodium, and potassium. Leachate analyses of fresh ashes indicate large amounts of adsorbed sulfate and chlorine, and moderate quantities of adsorbed fluorine. During the eruption, nearly all sulfur that was not present as microphenocrystic anhydrite was released as vapor; at least 35% of the chlorine was degassed, and only 10% of the fluorine. Vapor transport of metals was limited in the eruption plume. Nearly 30% of the vaporous sulfur in the plume was adsorbed onto ash particles, probably after oxidation to sulfate, and thereby carried to the ground. The rest of the vaporous sulfur was injected into the stratosphere, presumably as SO2. The exceptionally high sulfur content of the El Chichón magma, estimated at about 2.6 wt.% SO3, resulted in a large stratospheric cloud of sulfuric acid aerosols which may have an impact on the earth's climate. © 1984."
"56143914600;7003935733;6505554749;","Some applications of satellite radiation observations to climate studies.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020895269&partnerID=40&md5=2a15a0054af9a256ae35fecd6e0adba1","The sensitivities of the longwave radiation emitted by the Earth-atmosphere system to variations in surface temperature and cloud amount are evaluated from observations. The technique used is linear regression applied to zonal average data sets of longwave radiation, cloud amounts, and surface temperature. The dependence of these sensitivity coefficients on different radiation and cloud data sets and on the time averaging period is examined. Based on simulations, a simple linear relationship is derived between the planetary albedo and the surface albedo for the case of clear skies.-from STAR, 21(24), 1983"
[No author id available],"Satellite measurements of radiation budget parameters.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020929878&partnerID=40&md5=f05a4bd6a2d090603ccbb0efc631866b","Determination of the radiation budget parameters at the top of the atmosphere and on the ground; sampling problems, including sources; conical scan radiometers; measurement of optical data of aerosols in the atmosphere; the interactions of clouds and radiation; and comparison between radiation budget components derived from climate modeling and satellite measurements are discussed. Individual titles are abstracted separately.-from STAR, 22(10), 1984"
"7003814396;6602728596;","A Fast Solar Radiation Transfer Code for Application in Climate Models",1983,"10.1007/BF02275091","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020874114&doi=10.1007%2fBF02275091&partnerID=40&md5=4319f990a6df7b4a6217a5f11d190ed6","A method is presented for the calculation of solar heating rates in turbid and cloudy atmospheres. In contrast to other typical two-stream procedures, the system of differential equations describing the radiative transfer is decoupled through the application of a series expansion of the flux densities resulting in a single analytical expression for each flux. The present method (PM) yields a solution for the entire atmosphere instead of individual atmospheric layers. This procedure avoids as part of the solution scheme the inversion of a rather complex matrix thus resulting in high numerical efficiency. The model includes the absorption by atmospheric gases such as water vapor, CO2, O3 and NO2. This list can be extended if desired. Moreover absorption by aerosols and cloud particles is accounted for in addition to multiple scattering. A comparison with the rather accurate and already efficient transfer code of Zdunkowski et al. [6] shows that the present method is similarly accurate but numerically even more efficient. Therefore, this radiation scheme becomes very suitable for use in some circulation models of the atmosphere, such as prediction models of radiation fog.[/p] © 1983 Springer-Verlag."
"6602199552;55547129175;6601955569;6506300959;","Surface mesoscale features as potential storm predictors in the northern great plains-Two case studies",1983,"10.1175/1520-0493(1983)111<0273:SMFAPS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013847959&doi=10.1175%2f1520-0493%281983%29111%3c0273%3aSMFAPS%3e2.0.CO%3b2&partnerID=40&md5=60a8c5674d064938e1286b81eb8cc6ee","Two mesoscale case studies in the semi-arid climate of southeastern Montana were carried out on 1 May and 3 June 1980. I May was an unstable, rainy day with two rain periods over the mesonet area, and 3 June was a potentially unstable day, with a cold frontal passage in the afternoon producing a very intense convective event. Data from an instrumented mesoscale network (supporting the HIPLEX Montana experiment located between Miles City and Baker), a 5 cm radar, soundings, satellite (GOES), and synoptic maps were considered. The mesonet wind, temperature and moisture data were processed, computed every 15 min, and compared with radar rain patterns. The study confirmed that convergence cell development within the surface kinematic fields precedes radar echoes and is directly related to the convective event. The areas involved in the vertical motions generating storms are much larger compared to those reported in humid climates. The ""areal convergence"" is a better storm predictor than the maximum convergence point value. A cloud merging effect related to the storm intensity and reduced rain efficiencies were also found. The structure of the divergence field over the whole network experienced a cyclic evolution in both cases. This cyclic evolution is identified as a potential predictor for rain beginning 25-70 min after the last cycle before the rain phase. © 1983 American Meteorological Society."
"55275769500;7004540083;","The International Satellite Cloud Climatology Project ( ISCCP): the first project of the World Climate Research Programme.",1983,"10.1175/1520-0477-64.7.779","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021041625&doi=10.1175%2f1520-0477-64.7.779&partnerID=40&md5=3f6e4eccdc7ac38eac363602890b7e9d","The International Satellite Cloud Climatology Project (ISCCP) has been approved as the first project of the World Climate Research Programme (WCRP) and will begin its operational phase in July 1983. Its basic objective is to collect and analyze satellite radiance data to infer the global distribution of cloud radiative properties in order to improve the modeling of cloud effects on climate. ISCCP has two components, operational and research. -from authors"
"23476370700;","Parameterization of cloud effects on the absorption of solar radiation.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040846209&partnerID=40&md5=d18dd53fcab8ec5e0dcb589e6ddda454","A radiation parameterization for the NASA Goddard climate model was developed, tested, and implemented. Interactive and off-hire experiments with the climate model to determine the limitations of the present parameterization scheme are summarized. The parameterization of cloud absorption in terms of solar zenith angle, column water vapors about the cloud top, and cloud liquid water content is discussed.-from STAR, 22(7), 1984"
"7004547261;","Climate studies from satellite observations: Special problems in the verification of earth radiation balance, cloud climatology, and related climate experiments",1983,"10.1016/0273-1177(82)90113-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020952823&doi=10.1016%2f0273-1177%2882%2990113-2&partnerID=40&md5=d0b252f431eb9429a8d3876f6e933863","A body of techniques that have been developed and planned for use during the Earth Radiation Budget Experiment (ERBE), the International Satellite Cloud Climatology Project (ISCCP), and related climate experiments of the 1980's are reviewed. Validation and verification methods must apply for systems of satellites. They include: (1) use of a normalization or intercalibration satellite, (2) special intensive observation areas located over ground-truth sites, and (3) monitoring of sun and earth by several satellites and/or several instruments at the same time. Since each climate application area has a hierarchy of user communities, validation techniques vary from very detailed methods to those that simply assure high relative accuracy in detecting space and time variations for climate studies. It is shown that climate experiments generally require more emphasis on long-term stability and internal consistency of satellite data sets than high absolute accuracy. © 1983."
"7102581300;7005533663;","Analysis of cloud characteristics derived from archived satellite data",1983,"10.1080/01431168308948537","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020642088&doi=10.1080%2f01431168308948537&partnerID=40&md5=3b0e264717365cd9a126b56a02820410","The potential for retrieving cloud amount data from satellite-derived radiation budget archives is investigated. A predictive relationship between cloud cover and satellite-derived system albedo is established and used to produce a new oceanic cloud climatology. In view of the spatially and temporally discontinuous nature of cloud data and the diverse requirements of the three major users (i.e. scientists concerned with weather forecasting, environmental remote sensing and climate modelling), the following recommendations are made: (I) Radiance data, not cloud data, should be archived directly from satellite observations. (2) The highest spatial and temporal resolutions available should be retained in the archive. (3) Detailed comparative studies between surface and satellite assessments of cloud climatologies should be undertaken. © 1983 Taylor and Francis Ltd."
"6505860233;","ALBEDO OF THE SURFACE-CLOUDY ATMOSPHERE SYSTEM.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020883723&partnerID=40&md5=18a4cf2b377db2f359c132d0336cec69","Recommendations are made on simplifying calculations on the albedo A//c of the Earth-atmosphere system for a cloudy atmosphere in relation to large-scale and mesoscale meteorology and climate theory. Effects are established from the latitude and the height of the cloud layer on A//c for single-layer cloud. Estimates are made of the contributions from each layer and from the surface to the albedo for one- and two-layer clouds."
"7006393951;6602272898;6505786318;57200780967;6504791819;","The influence on the radiation regime and climate of dust aerosols and extensive cloud cover.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021066081&partnerID=40&md5=aad6f1aeb929dec6b76d6ddbfeed8d32","Results of two expeditions, to the Kara-Kum desert and to the Arctic and Kamchatka, are presented, (GAREX-I and GAREX-II).- D.G.Tout"
"7401491382;7403233451;","The climatological minimum in tropical outgoing infrared radiation: Contributions of humidity and clouds",1983,"10.1002/qj.49710945908","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021050799&doi=10.1002%2fqj.49710945908&partnerID=40&md5=a2379e9df7e0e85fbc6dfdfef6e672cd","Satellite observations of outgoing terrestrial infrared (IR) radiation as a function of latitude exhibit a minimum near the equator 20–40 Wm−2 smaller than peaks in the subtropics. We attempt to dissect the causes of the dip through calculations with a spectrally‐detailed multi‐level radiative transfer model. Roughly one third of the dip can be attributed to the latitudinal variation of atmospheric water vapour; the remainder apparently is due to latitudinal variations in cloud amount and (especially) cloud‐top height. However, inclusion of clouds as given by published climatologies enhances the clear‐sky dip only slightly. Thus, about one half of the dip is essentially unexplained. We suspect the explanation is that near‐equatorial cirrus and cumulonimbus heights are too low in the cloud climatology, emphasizing the need for a better cloud climatology. Since tropospheric humidity variations have a strong effect on clear‐sky outgoing IR, empirical studies which correlate cloud with IR variations may overestimate the effect of clouds on outgoing IR if cloud amount is correlated with relative humidity. The effect of humidity variations on outgoing IR suggests that a measure of tropospheric humidity be incorporated explicitly in the parametrization of outgoing IR for simple climate models. Copyright © 1983 Royal Meteorological Society"
"7103010852;7005412286;7003466102;7201706659;6701808711;","Observations of sea-surface temperature for climate research.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021052554&partnerID=40&md5=124daab7eecf71ca0db37f2e055855fd","The measurement of global sea-surface temperature (s.s.t.) from space, with high absolute accuracy, is one of the important requirements of the World Climate Research Programme. This paper considers the definition of measurement aims and gives as examples the possible influence of Pacific s.s.t. on the lower stratosphere, and the role of s.s.t. in the cloud-climate feed-back process. A brief review is presented on current status in satellite measurements of s.s.t. with both infrared and microwave techniques, there is a description of a future s.s.t.-measuring instrument, the Along-Track Scanning Radiometer. -Authors"
"7202988622;","Influence of water vapor on climate due to an increase in atmospheric carbon dioxide.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040846308&partnerID=40&md5=243c9b4c41187c5afb1f89f6f0831742","Water produces a significant greenhouse effect, not only in the vapor phase but also as a solid or liquid in the form of clouds. Water-vapor concentrations and cloud height and amount depends upon temperature which increases for a doubling of CO2. The change in temperature caused by the different water vapor concentrations and clouds was the purpose for this study. The assumption of a critical moist adiabatic lapse rate at low latitudes and a lapse rate for baroclinic adjustment at high latitudes both give a temperature increase of about 0.80 K for a doubling of CO2 although surface temperatures for present day CO2 do not agree well with observed temperatures.-from STAR, 21(23), 1983"
"6701877544;7202418453;","Global distributions of cirrus clouds determined from Sage data",1983,"10.1029/GL010i012p01180","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020874116&doi=10.1029%2fGL010i012p01180&partnerID=40&md5=3af67adbc6507588bb40c4e37a59c2f4","An analysis using SAGE data for the period February 1979 to April 1980 was performed to determine the spatial extent and frequency of cirrus clouds over a large portion of the earth's surface. These results should be of interest to, among others, both the researchers concerned with global monitoring and modeling of the earth's radiation budget and climate and to reentry vehicle designers concerned about anomalous aerodynamic effects or damage due to the ice particles found in cirrus clouds. A by‐product of the study reveals the statistics of tropospheric observational opportunities for a limb‐sounding satellite sensor by determining the percentage of times of successful penetration to 7 km. The results of the analysis showed that optically thick cirrus clouds are found most often in the mid‐latitudes and over the tropics with distinct minima near the ± 20 to 30° latitude bands. Thin cirrus clouds (as defined in this paper), on the other hand, occur much less often than the optically thick cirrus clouds. A comparison of the optically thick cirrus clouds observed by SAGE was made zonally with surface‐based observations and was found to generally agree. The percentage of tropospheric observational opportunities down to 7 km was as high as 60 percent in the upper latitudes but fell to about 30 percent in the tropics. This paper is not subject to U.S. copyright."
"57196694990;","Description of NCAR (National Center for Atmospheric Research) Community Climate Model (CCMOB).",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040845112&partnerID=40&md5=1606a7ce9bb528123a688bf832d49636","The details of the governing equations, physical parameterizations, and numerical algorithms defining the NCAR Community Climate Model (CCMOB) are presented. The presentation is ordered logically to match the code but does not make explicit reference to details of the code. The model uses the spectral transform method in the horizontal directions, finite difference approximations in the vertical direction, and semi-implicit time differences. The physical parameterizations include radiation with interactive clouds derived from the precipitation characteristics, convective adjustment, stable condensation, surface fluxes, and over nonocean points, a surface energy balance.-from STAR, 22(1), 1984"
"6602071516;","Diurnal and annual variation of climatic elements in Finland.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040845058&partnerID=40&md5=689bb2675fe0f81a4203bd78e6db8b6e","The diurnal and annual variations of various climatic elements in Finland based on hourly observations from 16 aero-nautical meteorological stations in 1970 to 1975 were investigated. Among the climate parameter discussed were: wind, atmospheric moisture, atmospheric pressure, clouds, fog, rain, and thunderstorms. The results are presented primarily as isopleth diagrams. Hourly mean values together with other statistics and distribution of diurnal variations are given. The main features of the diurnal and annual variations in climatic elements are typical of similar areas between 60o and 70oN. Finland's modified continental climate and many local factors explain most of the diurnal and annual variation.-from STAR, 22(18), 1984"
"7006689276;7003755700;6602194646;","Quantities of interest to climatology and atmospheric physics, volume 2.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040856976&partnerID=40&md5=8f1a1259adf01b1209d31195f0163f71","The accuracy of data collected from spaceborne Light Detection And Ranging (LIDAR) system is discussed as it effects the understanding of the atmosphere and the climate system. Topics such as temperature and wind profiles, planetary and surface albedo, sea surface temperature, and cloud studies are examined and compared with data from ground based stations and passive satellite radiometry.-from STAR, 22(16), 1984"
"36770633300;","Desertification.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020870467&partnerID=40&md5=4d7d91461c5e4262f04eaeb987357dbc","Considers definition, recognition, causes of, and current and desirable alternative responses to, desertification. Causes include changes in global wind circulation, successive droughts, but primarily man-made with aggravation by climate. Remedies for desertification include cloud seeding, diversion into natural depressions of rivers, 'greenbelts' of trees, water management on a small scale, fencing and control of grazing, planting of trees for firewood and windbelts, and re-seeding. For pastoral nomads to reduce herds (symbols of wealth), social and political problems must be faced.-M.J.Shepperdson (CDS)"
"7005807101;35779049500;","Enormous increase of stratospheric aerosols over Fukuoka due to volcanic eruption of El Chichon in 1982",1983,"10.1029/GL010i002p00152","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021081562&doi=10.1029%2fGL010i002p00152&partnerID=40&md5=3f3599f80318d978c31a0987ebe11ec2","Large increases of stratospheric aerosol particles caused by the eruption of Mexican volcano El Chichon in early April 1982 were observed by a Yag lidar system at two wavelengths (1.06 µm and 0.53 µm) over Fukuoka for three months since April 18. Most of the observations show high concentrations of aerosols in the altitude regions from 15 to 33 km, with highest concentrations between 21 and 30 km. The aerosol optical thickness at 0.55 µm is about 0.1 ‐ 0.3; this is about 10 to 30 times the maximum monthly mean values that were observed after the Mt. St. Helens event in 1980. The mean radius of aerosols in the densest part of the El Chichon cloud is estimated to be approximately 0.1 µm. This estimate is based on the slow settling velocity of the peak of the cloud and from information obtained by comparison of the two‐wavelength lidar returns. A significant impact of the presence of the cloud on the climate through variations of atmospheric circulation is suggested. Copyright 1983 by the American Geophysical Union."
"6602584454;","Spaceborne SAR imagery interpretation, Bahia area, Brazil.",1983,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021091132&partnerID=40&md5=16e6dd89ebd41e816fe68d4b1a4d4099","The interpretation of SAR imagery (L-band) of an area with a moist climate, both natural and cultivated vegetation, and frequent cloud cover shows that the features detected coincide quite well with imagery of other remote sensors such as X-band SAR, Landsat MSS Band 7 and conventional aerial photographs. Because of larger scale and stereoscopy, the photos give sharper details of lithologies and structures. Combined with fieldwork, the SAR imagery proved to be a useful tool for investigation of vegetated areas. -Author"
"35571076700;","Purposeful and accidental weather modification: our current understanding",1983,"10.1080/02723646.1983.10642235","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020866739&doi=10.1080%2f02723646.1983.10642235&partnerID=40&md5=6e510bcf4006d8702ca7f98cb2312d5a","The fields of planned and inadvertent weather are reviewed. The history, major problems, current scientific status, and research needs are assessed. Planned weather modification has been plagued by groups with conflicting interests and views, and most of the major U.S. experiments have failed owing to various problems. Basic research in cloud physics and dynamics is needed but the field now has the expertise and instrumentation to make major advances. Inadvertent weather modification studies have defined many of the urban influences but studies of regional-scale effects from irrigation and aircraft contrails need to be pursued. Studies are recommended to define better the social and environmental impacts from altered weather. © 1983 Taylor & Francis Group, LLC."
"7005965757;7006518289;","General circulation model experiments on the climatic effects due to a doubling and quadrupling of carbon dioxide concentration",1983,"10.1029/JC088iC11p06600","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020800369&doi=10.1029%2fJC088iC11p06600&partnerID=40&md5=760c1716c486aea1ac84b3613fe288f8","A global, spectral atmospheric general circulation model (GCM) with an energy balance ocean formulation, sometimes referred to as a swamp ocean, and realistic geography is run for doubled and quadrupled the present amount of atmospheric carbon dioxide, CO//2, with fixed and computed clouds. All experiments are compared to control runs with the present amount of CO//2. The experiments use annually averaged solar forcing; thus, there is not a seasonal cycle. The results indicate warming due to increased CO//2 is smaller than that found in other studies with swamp-ocean models coupled to atmospheric GCMs. One possible explanation may be attributed to large differences in the various models used, especially with regard to snow-sea ice albedo parameterizations."
"6603820694;7004289682;7003723817;","Microwave remote sensing of snow cover",1983,"10.1080/01431168308948536","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020642086&doi=10.1080%2f01431168308948536&partnerID=40&md5=70fece07876c48b79f77c6a3da19400f","The extent of the snow cover, the stored amount of water and the state of the snow metamorphism, in particular the date of the snow-melt and the intensity of the run-off, are of prime importance to hydrology and water management in large regions as well as to weather and climate. Regular observations by satellite-borne sensors can substantially improve the information on the status and the dynamic behaviour of these hydrologic parameters on a global scale. Microwave radiometers or scatterometers as all-weather and day and night sensors are excellent tools for reliable observations of cloud-covered regions of the world. The interaction of microwaves with snow strongly depends on snow wetness and size and structure of snow grains. Multifrequency observations can be used to classify snow conditions, to estimate the water equivalent or dry snow and to determine the start of the melting period. Results of several years of ground-based microwave observations along with classical hydrologic measurements are discussed and experience with satellite-borne microwave radiometers for the determination of the extent and state of the northern hemispheric snow cover is reported. Conclusions are drawn to define optimum sensor specifications for satellite-borne microwave remote sensing of the snow cover. © 1983 Taylor and Francis Ltd."
"7406514318;","The seasonal response of a general circulation model to changes in CO2 and sea temperatures",1983,"10.1002/qj.49710945906","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021081565&doi=10.1002%2fqj.49710945906&partnerID=40&md5=2bbcc2b71ec1c68afb7129ceb9932689","The seasonal response of an atmospheric general circulation model to changes in atmospheric carbon dioxide concentrations and sea surface temperatures is discussed. The model has five layers and a quasi‐uniform 330km horizontal grid. Sea surface temperatures, sea ice extents, and zonally mean cloud amounts are prescribed from climatology, so that feedbacks between these variables and the rest of the model are ignored. Soil moisture, snow depth and boundary layer height are modelled explicitly, and both diurnal and seasonal variations of solar zenith angle are included. Two experiments are carried out, and compared with a three‐year control integration. In each case, the model's response varies with season and location. In the first experiment the effect of increasing atmospheric carbon dioxide concentrations with prescribed present day sea surface temperatures is examined. The model's troposphere becomes warmer, thereby increasing the low level static stability over the ocean and reducing evaporation and precipitation. The warming is larger over land than over the oceans. In summer, this results in an increase in precipitation along the eastern coasts of continents. In the second experiment, the sea surface temperatures are increased by 2 K and the carbon dioxide concentration is doubled. The land surface temperature rises by 3 K. Evaporation increases markedly over the oceans. Precipitation increases in the main regions of atmospheric convergence and decreases in some regions of the subtropics. The magnitude of the model's response is shown to be reasonably consistent with that found in other three‐dimensional climate models. Copyright © 1983 Royal Meteorological Society"
[No author id available],"ISCCP cloud algorithm intercomparison workshop.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020219755&partnerID=40&md5=9b28975218150c20ffa51612a4171e5c","The ISCCP is designed to provide a global climatology of radiances and derived cloud optical properties to characterize the distribution and variation of clouds and their effects on Earth's radiation budget. The congruence between improved ability to retrieve atmospheric, surface and cloud optical properties from satellite-observed radiances and improved ability to incorporate realistic optical properties in climate models focuses on determination of cloud radiative properties. Currently available cloud analysis algorithms, initiated in late 1981, were compared.-from STAR, 23(1), 1985"
"7102113534;7401924358;","A climate index derived from satellite measured spectral infrared radiation.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020235772&partnerID=40&md5=bf6495863a6420a7fc76fd36be8d594d","The vertical infrared radiative emitting structure (VIRES) climate index, based on radiative transfer theory and derived from the spectral radiances typically used to retrieve temperature profiles, is introduced. It is assumed that clouds and climate are closely related and a change in one will result in a change in the other. The index is a function of the cloud, temperature, and moisture distributions.-from STAR, 20(16), 1982"
"7201635744;7006783796;56268091100;","Cloud cover sampling capability of various satellite combinations for ISCCP.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020219477&partnerID=40&md5=5c0484e656cfd0a8aa9003dc114278b0","One of the most important objectives of the ISCCP is the quantification of cloud cover and associated radiation parametes for climate research. The time-varying nature of cloud cover requires a measurement system that obtains cloud radiance at sufficient time intervals for determining accurate values of cloudiness for the appropriate averaging period. Current plans for the ISCCP call for such data to be acquired every three hours during both day and night to ensure that the diurnal cycle of cloud cover is adequately sampled. The satellite system proposed is an array of geostationary and polar-orbiting satellites. The error in mean cloud cover estimates for observation systems which do not include geostationary satellites are quantified.-from STAR, 23(1), 1985"
"57197652034;57217599247;","Parameterization of broadband solar radiation transfer in clear and cloudy atmospheres.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144462341&partnerID=40&md5=e8f805e326ce597588289b2f9ffca209","This report describes a parameterization model for computing solar heating rate and net flux profiles in clear and cloudy atmospheres. Specifically, the model is designed to allow global circulation and climate modelers maximum flexibility when treating the effects of clouds on the atmosphere.-from STAR, 21(14), 1983"
"7102783229;7006329853;57197483047;36818385000;7006057354;","Simulation studies of the physical and chemical processes occurring in the stratospheric clouds of the Mount St. Helens eruptions of May and June 1980.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020235283&partnerID=40&md5=bdce6b15180caaaa308fd3fc4f5c00ff","The large and diverse set of observational data collected in the high-altitude clouds of May 18, May 25, and June 13, 1980 was organized and analyzed for trends which reveal the processes at work. The data were used to guide and constrain model simulations of the volcanic eruptions. It is found that the volcano probably had little influence on the climate (less than 0.05 K global surface cooling) or on stratospheric ozone (less than 0.2% maximum hemispherical reduction).-from STAR, 21(2), 1983"
"7006689276;7801550627;","Changes of local planetary albedo by aerosol particles",1982,"10.1016/S0166-1116(08)71018-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956984784&doi=10.1016%2fS0166-1116%2808%2971018-5&partnerID=40&md5=1e71e89a73daa1c4cb59880353d64015","The climate parameter local planetary albedo is affected both in clear and cloudy areas by aerosol particles. In both cases the albedo may increase or decrease if turbidity increases, i.e. there are areas where an additional pollution leads to an energy gain or loss. While the most important parameters in clear areas are surface albedo and the mass absorption coefficient of the particles, aerosol particle concentration via the number of condensation nuclei and again absorption are the dominating factors in clouds. A reappraisal of known bulk formulae for clear areas points to additional parameters determining the crossover from heating to cooling. The most important additional parameter is sun elevation, however, aerosol optical depth also has to be considered. The weakness of former estimates of cloud albedo change with aerosol particle characteristics is demonstrated for broad cloud drop size distributions and for simultaneous changes in particle number, size, and chemical composition. The terrestrial radiation does not compensate for the partly drastic changes in the solar radiation in clear and cloudy areas, again pointing to a strong influence of aerosol particles on local planetary albedo."
"23476370700;","Documentation of the solar radiation parameterization in the GLAS climate model.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020219967&partnerID=40&md5=6e4e10234bb9466efeac9d466b1f9abd","The parameterization of solar radiation in the Goddard Laboratory for atmospheric sciences (GLAS) general circulation model (GCM) is described. It explicitly considers the directional nature of the direct solar beam in treating radiative transfer within clouds, and in treating the effect of surface reflection. This is accomplished using delta Eddington and delta 2 stream models for the radiative transfer within isolated atmospheric layers, and by coupling the individual layers together by efficiently repeated applications of the interaction principle.-from STAR, 20(21), 1982"
"7102589635;7005203072;7003519264;","Relative influence of selected cloud types and amounts on human energy budgets and skin temperatures",1982,"10.1007/BF02184620","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020002378&doi=10.1007%2fBF02184620&partnerID=40&md5=ad1e2a3f0b3cb4c90ef6043bea49177b","The combination of two deterministic and previously validated models of solar attenuation and outdoor human energy budgets and skin temperatures made possible the systematic examination of the effects of different cloud types and amounts on a person standing on an unobstructed plain. The results implied that the consequent relationships might be universal for most (summer) climates and latitudes. Relative rates were defined here as fractions of energy budget item rates under clear, cloudless conditions and high solar elevations. The resultant skin temperature deviations were very conservative when exposed to drastically changing cloud and thermal regimes. © 1982 Swets & Zeitlinger B.V."
"7005793728;7003991093;57198369060;","Cloud/climate sensitivity experiments.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040844486&partnerID=40&md5=bdc7e4a8aff91d2a2bab7088e13cc4cf","A study of the relationships between large-scale cloud fields and large scale circulation patterns is presented. The basic tool is a multi-level numerical model comprising conservation equations for temperature, water vapor and cloud water and appropriate parameterizations for evaporation, condensation, precipitation and radiative feedbacks. Incorporating an equation for cloud water in a large-scale model is somewhat novel and allows the formation and advection of clouds to be treated explicitly.-from STAR, 21(11), 1983"
"57203400519;","The effect of brokenness on cloud-climate sensitivity.",1982,"10.1175/1520-0469(1982)039<1853:TEOBOC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020330273&doi=10.1175%2f1520-0469%281982%29039%3c1853%3aTEOBOC%3e2.0.CO%3b2&partnerID=40&md5=d5626c0cb189e1157e8351eeac396c70","A study has been made of the effect of brokenness on the infrared and albedo feedback of clouds in climate models using a simplified treatment of broken cloudiness. It is shown that the individual feedback terms computed using the plane-parallel assumption differ markedly from the computations performed for a regular array of cuboidal clouds. -from Author"
[No author id available],"National Climate Program.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040844975&partnerID=40&md5=2bcde3740ee4c0452ffb99829404cd0b","This third annual report of the National Climate Program contains a summary of significant achievements during fiscal year 1981. The major aspects of progress during 1981 were as follows: in the short term, there were significant steps in measurements of the upper atmosphere and in processing and disseminating data for assessments, research, and applications; in the intermediate term, progress was made in diagnostic studies of climate and in developing objective forecast verification techniques; and, for the long term, there was progress in planning for ocean climate field programs and for studying the role of clouds in climate.-from STAR, 22(5), 1984"
"7101772062;","Possible physical mechanisms: dynamic coupling.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020235261&partnerID=40&md5=89141e4287a5488862bdb4c1f517c979","Physical effects linking solar variability and climate seem to be limited to changes in the concentrations of ions and variations in the atmospheric electric field. It is shown that there are possible dynamic processes involving planetary waves and convective clouds that might provide coupling between solar variability and short- term fluctuations in weather and climate. In both cases the arguments at present involve considerable speculation.-L.F.Musk"
"6602970656;55605772065;","Climatic applications of a satellite snow/ cloud discrimination sensor.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020435056&partnerID=40&md5=f192faaec8bd0136a57766208888c6b2","The purpose of the study was to evaluate the data from this sensor in its present form to determine its worth for improving snow and cloud interpretation from satellite photos and related impacts to climate studies. -D.G.Tout"
[No author id available],"National climate program annual report 1982.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040854924&partnerID=40&md5=f3fd329533e706d0c47f3a33e62a9814","Ash particles and sulphuric acid droplets from the El Chichon volcanic eruption in Mexico have formed a statospheric cloud which scatters sunlight and reduces the amount of solar heat reaching the earth. Because the El Chichon cloud is so huge and its absorption of sunlight may last for several years, there is reason to expect that it may cause changes in climate. A model simulation by NASA's Goddard Laboratory has estimated a yearly decrease in global average temperature of as much as 0.25oC beginning in 1984. -from CEGB Digest"
"57168336200;6507784949;","Dynamics of the modern climate of polar regions.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020217077&partnerID=40&md5=cbe47581b65bf188cbc193753730116c","The temporal variations (primarily during the 1938-1981 period) of the temperature, cloud cover, duration of the snowless period, atmospheric transmission, radiation balance, and the direct and total radiation are discussed. Present-day cooling in the polar regions is occurring against a background of reduced cloud cover and duration of the snowless period, an increase in the sea ice, and a reduction in the surface radiation balance despite an incresae in the direct and total radiation.-from Journal summary"
"6701518478;","The feasibility of estimating solar radiation flux distributions from 'bright' sunshine data ( New Zealand).",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020354560&partnerID=40&md5=f4029aeaf2f406648ee8128f8703582b","During whole hours when uninterrupted sunshine is possible the observed sunshine fractions for New Zealand's maritime climate form a U-shaped frequency distribution. A simple physical model of radiation flux for sun-shining and sun-obscured situations at a given solar zenith angle is extended to include cloud cover data and a partition of diffuse radiation between circumsolar and all-sky components.-from AuthorSunlight insolation cloud cover sky brightness solar radiation flux density illuminance irradiance frequency distribution."
"7003708866;","The urban climate.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040297100&partnerID=40&md5=8eec41ab2f20bb03cc09468870b5bb19","Since the first descriptive accounts of urban climates, emphasis has shifted towards the physical understanding of rural-urban differences in the atmospheric boundary layer. This book aims to summarise this knowledge, concentrating on work done during the last decade and a half. It includes chapters on: the urban atmosphere; urban air composition; urban energy fluxes; the urban heat island; urban wind field; models of urban temperature and wind fields; moisture, clouds and hydrometeors; urban hydrology; and urban planning. -L.F.Musk"
"13102593000;","The role of aerosols in the climate system: Results of numerical experiments in climate models",1982,"10.1016/0273-1177(82)90322-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020897834&doi=10.1016%2f0273-1177%2882%2990322-2&partnerID=40&md5=4be22541161a747fdde862b87fb072ac","Three principal questions are recurrent with the consideration of an aerosol related climatic effect: (1) do aerosols heat or cool the atmosphere, (2) are aerosol climatic effects significant and (3) can numerical models be validated by predicting a climatic change associated with a measured aerosol-event. Each of these questions will be addressed from a historical perspective. In addition, the most recent aerosol-related modeling will be discussed as well as recommendations for future research. © 1983."
"7101952183;7404577357;","Formation of noctilucent clouds by an extraterrestrial impact.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020430144&partnerID=40&md5=0b68a56d7e3df84f431fd9b42cdfccc3","The impact of a large body in the oceans would inject large quantities of water through the tropopause cold trap into the stratosphere and lower mesosphere. We consider the consequences of enhanced water vapor concentrations on the middle atmosphere (50- 100 km) chemistry and heat budget. The globally-averaged albedo resulting from these clouds is dependent on the particulate size and shape, and can be as high as several percent, preferentially covering the summer hemisphere. This could have important implications for the short-term climate following a large-body impact. -from Authors"
"6602484059;7101769617;6701318848;","Influence of rainfall on the seasonal variations of cloud condensation nuclei concentrations in a sub-equatorial climate ( Abidjan).",1982,"10.1175/1520-0469(1982)039<2076:IOROTS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020177942&doi=10.1175%2f1520-0469%281982%29039%3c2076%3aIOROTS%3e2.0.CO%3b2&partnerID=40&md5=1c243c5db6f1c80f3ce6d7c69facd1df","Systematic measurements of cloud condensation nuclei (CCN) concentration have been carried out in the Abidjan area from December 1977 to June 1978, at 0700 local time (corresponding to a daily maximum). In May and June 1978, during the continuous monsoon rains, the concentrations substantially increased, this effect being more important for the fraction of the less active CCN. Nuclei of continental origin accompanying dust haze in December 1977 were progressively eliminated from the atmosphere by dry or wet deposition. -from Authors"
"7006689276;7801550627;","Changes of local planetary albedo by aerosol particles",1982,"10.1016/0048-9697(82)90148-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020070457&doi=10.1016%2f0048-9697%2882%2990148-6&partnerID=40&md5=cdf857600b3481f07caee2847c161605","The climate parameter local planetary albedo is affected both in clear and cloudy areas by aerosol particles. In both cases the albedo may increase or decrease if turbidity increases, i.e. there are areas where an additional pollution leads to an energy gain or loss. While the most important parameters in clear areas are surface albedo and the mass absorption coefficient of the particles, aerosol particle concentration via the number of condensation nuclei and again absorption are the dominating factors in clouds. A reappraisal of known bulk formulae for clear areas points to additional parameters determining the crossover from heating to cooling. The most important additional parameter is sun elevation, however, aerosol optical depth also has to be considered. The weakness of former estimates of cloud albedo change with aerosol particle characteristics is demonstrated for broad cloud drop size distributions and for simultaneous changes in particle number, size, and chemical composition. The terrestrial radiation does not compensate for the partly drastic changes in the solar radiation in clear and cloudy areas, again pointing to a strong influence of aerosol particles on local planetary albedo. © 1982."
"6506733753;","Climate defeats energy planners in Sri Lanka",1982,"10.1016/0360-5442(82)90049-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020090758&doi=10.1016%2f0360-5442%2882%2990049-4&partnerID=40&md5=b9ff154613887e9192c988ca7aa79204","Changes in climatic conditions and vagaries of rainfall have seriously affected Sri Lanka's hydro-electric power supplies. The country's planners, who thought that the 1980 installed capacity of 421 MMW would be sufficient to meet present needs, have been compelled to resort to power cuts. Attempts to seed rain clouds with Thai expertise have also failed. The bulk of the country's power supply comes from hydro-plants while thermal plants are used as a back-up source, the yield from this source is 20 MMW. © 1982."
"57217712932;","Formation of noctilucent clouds by an extraterrestrial impact",1982,"10.1130/SPE190-p211","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879594305&doi=10.1130%2fSPE190-p211&partnerID=40&md5=bb9442752897500e21ff4dd192ca10b5","The impact of a large body in the oceans would inject large quantities of water through the tropopause cold trap into the stratosphere and lower mesosophere. We consider the consequences of enhanced water vapor concentrations on the middle atmosphere (50-100 km) chemistry and heat budget. The increased mixing ratio of hydrogen dramatically decreases the ozone concentration above 60 km. Catalytic reactions with odd hydrogen are the main sink of ozone in this region. The ozone reduction causes a lowering of the average height of the mesopause, as well as a lowering of the average temperature. The lower colder mesopause and the creation of saturation conditions over much of the upper mesosphere would have resulted in a permanent layer of mesospheric ice clouds of nearly world-wide extent. (At present, these exist only at high latitudes and are observed in summer as ""noctilucent clouds."") The globally-averaged albedo resulting from these clouds is dependent on the particulate size and shape, and can be as high as several percent, preferentially covering the summer hemisphere. This could have important implications for the short-term climate following a large-body impact. Similar effects would also result from an encounter with a more extended object such as a swarm of cosmic debris or a dense interstellar cloud."
"7006033615;6507162227;","The parameterization of longwave flux in energy balance climate models.",1982,"10.1175/1520-0469(1982)039<2144:TPOLFI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020330192&doi=10.1175%2f1520-0469%281982%29039%3c2144%3aTPOLFI%3e2.0.CO%3b2&partnerID=40&md5=05667c93ec00d73d6dddc81ac8f13cc4","Many climate models of the energy balance type parameterize the zonally-averaged infrared flux at the top of the atmosphere in terms of the surface (or sea level) temperature T and cloud cover. Most recent studies have used the annual average data of Ellis and Vonder Haar (1976), and it leads to tolerable parameterization errors. However, we see here that when such formula are used to simulate the seasonal cycle, very large errors are incurred. These errors are not greatly reduced if the regression coefficients are deduced by fitting the seasonal data. -from Authors"
"7102783229;7006329853;57207907145;36818385000;35227443900;","Noctilucent clouds: Simulation studies of their genesis, properties and global influences",1982,"10.1016/0032-0633(82)90126-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001262338&doi=10.1016%2f0032-0633%2882%2990126-X&partnerID=40&md5=102d95e07c92035b1934983d812cecb0","The formation, evolution and properties of noctilucent clouds are studied using a timedependent one-dimensional model of ice particles at mesospheric altitudes. The model treats ice crystals, meteoric dust, water vapor and air ionization as fully interactive cloud elements. For ice particles, the microphysical processes of nucleation, condensation, coagulation and sedimentation are included; the crystal habits of ice are also accounted for. Meteoric dust is analyzed in the manner of Hunten et al. (1980). The simulated particle sizes range from 10 Å to 2.6μm. The chemistry of water vapor and the charge balance of the mesosphere are also analyzed in detail. Based on model calculations, including numerous sensitivity tests, several conclusions are reached. Extremely cold mesopause temperatures (&lt;140K) are necessary to form noctilucent clouds; such temperatures only exist at high latitudes in summer. A water vapor concentration of 4-5 ppmv is sufficient to form a visible cloud. However, a subvisible cloud can exist in the presence of only 1 ppmv of H2O. Ample cloud condensation nuclei are always present in the mesosphere; at very low temperatures, either meteoric dust or hydrated ions can act as cloud nuclei. To be effective, meteoric dust particles must be larger than 10-15 Å in radius. When dust is present, water vapor supersaturations may be held to such low values that ion nucleation is not possible. Ion nucleation can occur, however, in the absence of dust or at extremely low temperatures (&lt;130K). While dust nucleation leads to a small number (&lt;10cm-3) of large ice particles (&gt;0.05 μm radius) and cloud optical depths (at 550 nm) ∼10-4, ion nucleation generally leads to a large number (∼103cm-3) of smaller particles and optical depths ∼10-5). However, because calculated nucleation rates in noctilucent clouds are highly uncertain, the predominant nucleus for the clouds (i.e., dust or ions) cannot be unambiguously established. Noctilucent clouds require several hours-up to a day-to materialize. Once formed, they may persist for several days, depending on local meteorological conditions. However, the clouds can disappear suddenly if the air warms by 10-20 K. The environmental conditions which exist at the high-latitude summer mesopause, together with the microphysics of small ice crystals, dictate that particle sizes will be ≲ 0.1 μm radius. The ice crystals are probably cubic in structure. It is demonstrated that particles of this size and shape can explain the manifestations of noctilucent clouds. Denser clouds are favored by higher water vapor concentrations, more rapid vertical diffusion and persistent upward convection (which can occur at the summer pole). Noctilucent clouds may also condense in the cold ""troughs"" of gravity wave trains. Such clouds are bright when the particles remain in the troughs for several hours or more; otherwise they are weak or subvisible. Model simulations are compared with a wide variety of noctilucent cloud data. It is shown that the present physical model is consistent with most of the measurements, as well as many previous theoretical results. Ambient noctilucent clouds are found to have a negligible influence on the climate of Earth. Anthropogenic perturbations of the clouds that are forecast for the next few decades are also shown to have insignificant climatological implications. © 1982."
"57217549674;","Soviet national Middle Atmosphere Program.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020216733&partnerID=40&md5=e83212e91e625a3199b5242ea0ec6f0a","Soviet national MAP program comprises seven projects: lower thermosphere (structure and dynamics); high latitude energetic sources and their effect on the structure and dynamics of the upper atmosphere under conditions of the polar night; climate of the stratosphere and mesosphere (effects of various energetic sources on its formation); winter variability in the lower ionosphere; noctilucent clouds (climatology, dynamics, nature, and genesis); wave processes and structure and dynamics of the stratosphere and mesosphere; and dynamics of the ozone layer. -from STAR, 23(11), 1985"
"6602653884;","The effect of altitude on the daily range of temperature",1982,"10.1002/joc.3370020407","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020347868&doi=10.1002%2fjoc.3370020407&partnerID=40&md5=6034c0f750085da82fe46c423f72406f","Although it has been claimed that the daily range of screen temperature increases with altitude on a mountain, this appears not to be true generally. Data from sixteen sources indicate a confusion of evidence, though there appears to be some evidence of an increase of daily temperature range with height from 0‐200 m, and of a decrease between 750 m and 3400 m. The low‐altitude increase is attributed to the sea's moderating influence at the coast. The higher altitude decrease may be due to stronger winds or to more cloud. The evidence for a decrease may be confounded in some places by either peculiarities of locale or the increased daily fluctuation of radiation at highest altitudes. Copyright © 1982 John Wiley & Sons, Ltd"
"57212256445;7401456188;","Reflected solar radiances from regional scale scenes ( Saudi Arabian empty quarters, Himalayas, Arabian Sea ,India, Hudson Bay).",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020206672&partnerID=40&md5=5cdab55b702369dcdbac5602993589f8","A set of bi-directional reflectance models is presented for various atmospheric scene types. The models were composited from data collected from an aircraft platform in May-July 1979 during Summer MONEX. The space scale of the composited models is generally from 250-1000 km, which corresponds to the scale of interest in climate monitoring and modeling. Composite models for the following scene types are presented: the desert sands of the Saudi Arabian Empty Quarters, the Himalayan mountains, the Arabian Sea with the ever-present fair weather cumulus cloudiness, the semi-arid agricultural land surface of the Indian subcontinent under pre-monsoon conditions, broken middle and low level clouds over ocean, an altostratus cloud deck, and the broken pack-ice fields of Hudson Bay.-from Authors"
"7004983984;7004100461;","Chemistry of the unpolluted and polluted troposphere. Proceedings of the NATO Advanced Study Institute, Corfu, September 28-October 10 1981.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040296895&partnerID=40&md5=5dde8f847498cc8a49b16519b9b0e13c","The 25 papers in the proceedings are the result of research in several disciplines. Those in the first part present problems in, and methods of, measuring trace gases and aerosols before treating the thermodynamic structure of the atmosphere, its influence on transport and distribution of trace compounds, and the interactions between trace compounds and climate. The next topic deals with atmospheric cycles of some of the more important trace elements and compounds. Papers in the next section discuss the fact that the troposphere is not a homogeneous gas phase, but rather a region in which a great number of heterogeneous chemical and physical processes occur in cloud and precipitation droplets, or at the surface of particles. The final section deals with pollution problems. Papers are abstracted separately. -after Editors"
"7005608266;","Predicting bare soil temperature. I. Theory and models for the multi‐day mean diurnal variation",1982,"10.1111/j.1365-2389.1982.tb01758.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020453138&doi=10.1111%2fj.1365-2389.1982.tb01758.x&partnerID=40&md5=cbf938460475d9d909d457603aeeafce","The energy balance equation for the soil‐air interface is expressed, by suitable approximations, in a form linear in the surface temperature T0. This forms the basis of two predictive models for the diurnal variation of T0, averaged over a many‐day interval, for potentially evaporating bare soil. Input data include total solar radiation, air temperature and vapour pressure, windspeed ua, cloud cover c, and soil radiative, aerodynamic and thermal properties (the latter assumed uniform). In the simpler model, based on harmonic analysis, ua and c are assumed constant. For Nt observations per day, an algebraic solution is found as a set of equations for the parameters of up to the first Nt/2 harmonics. In the second model, dynamic wind‐speed is introduced, and a more complicated linear algebraic method of solution is required. The models have agroclimatic value, since by averaging they predict the thermal ‘climate’ of soil, in contrast to instantaneous models which describe the time‐specific thermal ‘weather’. Copyright © 1982, Wiley Blackwell. All rights reserved"
"56036694200;7004079572;","Parametric study of the effects of arctic soot on solar radiation",1982,"10.1016/0004-6981(82)90057-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020002375&doi=10.1016%2f0004-6981%2882%2990057-9&partnerID=40&md5=dd9855149db3cf312ee65ed6134b4af8","A numerical radiative transfer model has been used to simulate the possible effects of carbonaceous aerosol on the Arctic climate. Because of uncertainties in aerosol properties in the Arctic, the sensitivity of modeled components of the solar radiation budget to ranges in aerosol parameters was determined. It was found that differences in assumed aerosol absorption, concentration and vertical distribution were more important than differences in aerosol size distribution. Aerosol absorption was parameterized through the index of refraction assuming an aerosol composed of soot and sulfates. Modeling the radiative effects of the springtime phenomena of Arctic soot leads to an increase in average heating rates of 0.01-0.06 K day-1 in the lowest 1-5 km of the atmosphere under cloud free conditions. The higher value is similar to estimated heating rates at northern latitudes that would result from doubling atmospheric CO2 concentrations. The hemispheric average temperature change due to the Arctic soot is, however, estimated to be almost two orders of magnitude less than for doubling of CO2 concentrations. © 1982."
"7006393951;57193156372;7003922483;","The effect of aerosols on climate and aerosol climatology on the basis of observations from space",1982,"10.1016/0273-1177(82)90321-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020935493&doi=10.1016%2f0273-1177%2882%2990321-0&partnerID=40&md5=05731e65e71c1bdd1561a305991621dd","Principal aspects of the effect of aerosols on climate are discussed and the possibilities of obtaining a climatic data set of global aerosols are analyzed. Based on the analysis of space images, new data have been obtained on gigantic dust outbreaks in various regions of the Earth. It has been shown that dust outbreaks can propagate over hundreds and sometimes thousands of kilometers. The western Sahara - Atlantic Ocean is the major region of propagation of these outbreaks. The continent-to-continent trajectories of dust clouds have been discovered (from Africa to the coast of America, from Central Asia to the Pacific Ocean). Maps of the sources of strong dust transformations have been studied and drawn. In particular, an anthropogenic dust source has been found out on the northeastern coast of the Aral Sea. A striped mesostructure of dust formations has been analyzed, determined by both the inhomogeneous surface and peculiarities of the eddy dust transport. The techniques have been discussed in detail for retrieving the parameters of aerosol size distribution and the vertical profiles of the coefficients of aerosol extinction in the stratosphere and lower mesosphere from the data on the brightness of the twilight and daytime horizon as well as occultation measurements of solar radiation attenuation by the atmosphere. The difficulty of reliably predicting possible environmental changes arises both from the problems of estimating complex interactions of numerous processes and from a lack of information concerning various environmental parameters. For example, an important factor in present day climatic changes is the increased dust content of the atmosphere due to man's activities. However, a reliable estimate of this influence is found to be impossible due to the absence of definitive data on the global distribution of atmospheric dust and the properties of dust in various parts of the world [4,5,13-15]. The impact of aerosols on climate has been discussed in detail in a number of monographs [12-15]. Observations from space have opened up new possibilities for studying atmospheric dust. For this purpose, both the imagery and spectrometry of the Earth's atmosphere from space are used. Rather attractive are the prospects for laser sounding [1]. © 1983."
"7202418453;","Aerosol measurements from earth orbiting spacecraft",1982,"10.1016/0273-1177(82)90331-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020948784&doi=10.1016%2f0273-1177%2882%2990331-3&partnerID=40&md5=47f5f35ea50f2e0c8e8f3a7c5103efc4","Since the fall of 1978, two Earth-orbiting spacecraft sensors, SAM II, for Stratospheric Aerosol Measurement II, and SAGE, for Stratospheric Aerosol and Gas Experiment have been monitoring the global stratospheric aerosol. These experiments use the Sun as a source to make Earth-limb extinction measurements during each spacecraft sunrise and sunset. This paper describes the global aerosol data base (climatology) that is evolving. Seasonal and hemispheric variations such as the springtime layer expansion with warming temperatures and the local wintertime polar stratospheric clouds (PSC's) will be described. The PSC's enhance extinction by up to two orders of magnitude and optical depths by as much as an order of magnitude over the background 1000 nm values of about 1.2 × 10-4 km-1 and 1.3 × 10-3, respectively. The detection and tracking of a number of volcanoes whose effluents penetrated the tropopause are also described. The mass of new aerosol injected into the stratosphere from each volcano is estimated. The May 1980 eruption of Mount St. Helens, for example, produced about 0.32 × 109 kg of new stratospheric aerosol enhancing the Northern Hemispheric aerosol by more than 100 percent. © 1983."
"7102783229;7006329853;7408416034;57207907145;7101673388;16510720600;","An analysis of the physical, chemical, optical, and historical impacts of the 1908 Tunguska meteor fall",1982,"10.1016/0019-1035(82)90096-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0002767381&doi=10.1016%2f0019-1035%2882%2990096-3&partnerID=40&md5=6aea64903cb53216f4f684a9844eb903","A detailed analysis of the physical nature and photochemical after effects of the explosive cometary meteor Tunguska is presented. The physical manifestations of the event (the acoustic and seismic waves, forest damage, and so on) are shown to be consistent with the entry of a 5-million-ton object into the Earth's atmosphere at 40 km sec-1. The meteor apparently had a very low effective density (&lt;0.01 g/cm3) due either to its intrinsic porous structure, to shattering in orbit far from the Earth, or to breakup upon initial impact with the Earth's upper atmosphere. Aerodynamic calculations are used to demonstrate that the shock waves emanating from the falling meteor could have generated up to 30 million tons of nitric oxide (NO) in the stratosphere and mesosphere. The photochemical consequences of such an immense Tunguska-related NO injection are investigated with the aid of a fully interactive one-dimensional chemical-kinetics model of atmospheric trace constituents. The first year after the Tunguska fall (from mid-1908 to mid-1909) a 35-45% hemispherical ozone depletion is predicted with the model; declining but still substantial ozone depletions are calculated in subsequent years. Atmospheric transmission data collected by a research team of the Smithsonian Astrophysical Observatory (APO) at Mount Wilson, California, from 1908 to 1911 are analyzed for ozone absorption in the Chappuis bands. Statistical analysis of the APO data reveals an ozone variation of 30 ± 15% over this period, supporting the theoretical predictions. The optical anomalies which followed the Tunguska event are reviewed for evidence of NOxOx chemiluminescent emissions, NO2 solar absorption, and meteoric dust turbidity. The chemical afterglows are shown to be intense enough to account for some of the unusual night-time light displays seen after the fall, but not widespread enough to explain the ""light nights"" and glowing skies reported throughout Eurasia. These phenomena appear to be related to the dust and water vapor deposited by the meteor at the cold summer mesopause, resulting in the formation of dense noctilucent clouds. Only circumstantial optical evidence for a large Tunguska NO2 enhancement is found, which can not be used to calibrate independently the NO injection by the meteor. The suggestion of a dust veil created by the Tunguska explosion is revealed by the APO transmission data. We deduce that nearly 1 million tons of pulverized dust may have been deposited in the mesosphere and stratosphere by the Tunguska fall, which agrees with previous estimates of the meteor mass influx. Possible climate changes triggered by the Tunguska event are investigated. The most important climate anomaly identified in the post-Tunguska era is a 0.3°K cooling of the Northern Hemisphere which lasted for almost a decade. Several large volcanic eruptions occurred during this period which also played a role in the temperature change. However, radiation transport calculations are reported which suggest that Tunguska contributed to the cooling trend. The lessons of Tunguska for other important geophysical problems, such as ozone/weather coupling and the ancient extinction of the dinosaurs, are also explored. It is concluded that more rigorous investigations of the physics and chemistry of the Tunguska event are warranted. © 1982."
"7004061048;7202208382;","An analysis of the cloud fields simulated by the GLAS climate model.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019647023&partnerID=40&md5=9a24739b7520c06a2ec37370554091a8","The cloud field produced by the climate model was analyzed. The following items are discussed: 1) reasonable cloudiness production by the model; 2) comparison of the amount of model generated cumulus cloudiness to supersaturation cloudiness; and 3) the size and effect of cumulus clouds on radiation balance. It is shown that the scattered, small scale cumulus clouds occur more frequently than the horizontally widespread supersaturation clouds in the low latitudes and mid troposphere.-from STAR, 20(16), 1982"
"7005203072;7003519264;","Canopy leaf temperatures and energy budget components affected by cloud types and amounts",1981,"10.1007/BF02263312","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019658608&doi=10.1007%2fBF02263312&partnerID=40&md5=3fae0ab6762fe78b9c54f2f921013b62","The combination of two deterministic and previously validated models of solar attenuation and canopy foliage made possible the systematic examination of the effects of different cloud types and amounts on the leaf temperature fields and selected energy budget components within a stand of plants. The results implied that the consequent trends might be universal for all climates, latitudes, and many plant types. © 1981 Springer-Verlag."
"7102508311;","The atmosphere of Venus",1981,"10.1007/BF00177144","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001878062&doi=10.1007%2fBF00177144&partnerID=40&md5=fb992eaf52e369e425a6d78a59a8c31c","The investigations of Venus take a special position in planetary researches. It was just the atmosphere of Venus where first measurements in situ were carried out by means of the equipment delivered by a space probe (Venera 4, 1967). Venus appeared to be the first neighbor planet whose surface had been seen by us in the direct nearness made possible by means of the phototelevision device (Venera 9 and Venera 10, 1975). The reasons for the high interest in this planet are very simple. This planet is like the Earth by its mass, size and amount of energy obtained from the Sun and at the same time it differs sharply by the character of its atmosphere and climate. We hope that the investigations of Venus will lead us to define more precisely the idea of complex physical and physical-chemical processes which rule the evolution of planetary atmospheres. We hope to learn to forecast this evolution and maybe, in the far future, to control it. The last expeditions to Venus carried out in 1978 - American (Pioneer-Venus) and Soviet (Venera 11 and 12) - brought much news and it is interesting to sum up the results just now. The contents of this review are: 1. The planet Venus - basic astronomical data. 2. Chemical composition. 3. Temperature, pressure, density (from 0 to 100 km). 4. Clouds. 5. Thermal regime and greenhouse effect. 6. Dynamics. 7. Chemical processes. 8. Upper atmosphere. 9. Origin and evolution. 10. Problems for future studies Here we have attempted to review the data published up to 1979 and partly in 1980. The list of references is not exhaustive. Publications of special issues of magazines and collected articles concerning separate space expeditions became traditional last time. The results obtained on the Soviet space probes Venera 9, 10 (the first publications) are collected in the special issues of Kosmicheskie issledovanija (14, Nos. 5, 6, 1975), analogous material about Venera 11, 12 is given at Pis'ma Astron. Zh. (5, Nos. 1 and 5, 1978), and in Kosmicheskie issledovanija (16, No. 5, 1979). The results of Pioneer-Venus mission are represented in two Science issues (203, No. 4382; 205, No. 4401) and special issue of J. Geophys. Res. (1980). We shall mention some articles to the same topic among previous surveys: (Moroz, 1971; Sagan, 1971; Marov, 1972; Hunten et al., 1977; Hoffman et al., 1977) and also the books by Kuzmin and Marov (1974) and Kondrat'ev (1977). Some useful information in the part of ground-based observations may be found in the older sources (for example, Sharonov, 1965; Moroz, 1967). For briefness we shall use as a rule the abbreviations of space missions names: V4 instead of Venera 4, M10 instead of Mariner 10 and so on. The first artificial satellites of Venus in the world (orbiters Venera 9 and 10) we shall mark as V9-O, V10-O unlike the descent probes V9, V10. Fly-by modules of Venera 11 and Venera 12 we shall mark as V11-F and V12-F. Pioneers descent probes - Large (Sounder), Day, Night and North - will be marked as P-L, P-D, P-Ni, P-No, orbiter as P-O, and bus as P-B. © 1981 D. Reidel Publishing Co."
"7202899330;7102389805;","Clouds and climate: sensitivity of simple systems.",1981,"10.1175/1520-0469(1981)038<0235:CACSOS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019696234&doi=10.1175%2f1520-0469%281981%29038%3c0235%3aCACSOS%3e2.0.CO%3b2&partnerID=40&md5=03e75727de7483cf8d726f1689e8281f","A 1-dimensional radiative convective model is used to gage the influence of clouds on simple climate systems. The radiative transfer model is developed to accommodate in a systematic and consistent manner the optical properties of a hierarchy of cloud types. Cloud albedo and emissivity relationships for both ice and water clouds are introduced. -from Authors"
"7501757094;7004540083;7403318365;7102425157;","Climate sensitivity of a one-dimensional radiative-convective model with cloud feedback.",1981,"10.1175/1520-0469(1981)038<1167:CSOAOD>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019696331&doi=10.1175%2f1520-0469%281981%29038%3c1167%3aCSOAOD%3e2.0.CO%3b2&partnerID=40&md5=c496d489e74c3f9a63b6f8f9191c41fd","We illustrate the potential complexity of the feedback between global mean cloud amount and global mean surface temperature when variations of the vertical cloud distribution are included by studying the behavior of a one-dimensional radiative-convective model with two types of cloud variation: variable cloud cover with constant optical thickness; and variable optical thickness with constant cloud cover. The model results show that changes in the vertical cloud distribution and mean cloud optical thickness can be as important to climate variations as are changes in the total cloud cover.-from Authors"
"7102018821;","Some aspects of the optical properties of ice clouds.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019751024&partnerID=40&md5=e5445635cccae9a1f13b750ecd3c5dee","In this report, the current understanding of the light scattering properties of ice crystals and the radiative characteristics of ice clouds has been reviewed comprehensively. The significance of light scattering and radiative properties of ice crystals are then discussed in connection with remote sensing and climate studies. Highlights of the single scattering properties of hexagonal columns and plates, derived from both laboratory experiments and theoretical calculation, are presented. In addition, the importance of cirrus clouds on the global radiative budget and the climate of the earth-atmosphere system will be discussed.-from Author"
"7006689276;","The climate at maximum entropy production by Meridional atmospheric and oceanic heat fluxes",1981,"10.1002/qj.49710745110","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019353438&doi=10.1002%2fqj.49710745110&partnerID=40&md5=16782ba87415ab13181db88e0883668a","In a zonally‐average energy balance climate model (principal features as with Paltridge 1975) with the four unknowns ‐ surface temperature T, cloud amount N, total meridional heat fluxes within the ocean and the atmosphere Om+Am, and total vertical heat flux LE+CH, the maximum entropy production by meridional heat fluxes is used as a constraint to solve the system for the four unknowns in all 10 boxes of the model. Since the solution at maximum entropy production by meridional heat fluxes agrees quite well with present mean conditions, this maximum principle is used as a working hypothesis for climate sensitivity studies avoiding the use of fixed cloud amount and meridional heat fluxes. the resulting sensitivities partly agree and disagree with those of similar energy balance climate models. Disagreement is particularly high if an ice‐albedo feed‐back is included. the feed‐back is strongly reduced because of opposing effects of cloud amount in high latitudes. Copyright © 1981 Royal Meteorological Society"
"7103410371;13102593000;","Carbon dioxide and climate: the effects of water transport in radiative-convective models.",1981,"10.1029/JC086iC12p12035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019711308&doi=10.1029%2fJC086iC12p12035&partnerID=40&md5=0f162d98ec63df6117fb3770d7edad21","The Hummel-Kuhn model yields temperature increases for doubled CO2 larger than the Manabe-Wetherald model for various assumed total cloud cover amounts. For assumed standard cloud cover amounts the Hummel-Kuhn estimate is 20% larger than the Manabe-Wetherald estimate. For reduced and enhanced cloud cover amounts the Hummel-Kuhn estimates are 37% and 17% larger, respectively.-from Authors"
"6701703475;","Data for radiation climatology.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019368797&partnerID=40&md5=f7502e8f36afa2d468407a93fbea9b8c","In 1980 WMO and ICSU agreed to sponsor jointly the World Climate Research Programme. Extensive use must be made of satellite observations to study the variability of the radiation fluxes and their interdependence with quantities generated by different processes like clouds, gases, aerosols and surface properties. - from Author"
"7004079572;","Causes of CO2-induced sensitivity in a zonal climate model.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040296917&partnerID=40&md5=a53366358b59aa0689d9d21d92f9de81","In a simulation using the LLNL two-dimensional climate model, increased CO2 and water vapor and decreased surface albedo lead to a strong warming of the surface-troposphere system. Changes in cloud amount and distribution, however, lead to slight cooling, thereby helping to buffer the climate change induced by a doubling of CO2. The separately calculated effects can very nearly be linearly combined to arrive at the total climatic response. -from STAR, 19(24), 1981"
"23091439900;57216049572;","Characteristics of West African and East Atlantic cloud clusters: a survey from GATE.",1981,"10.1175/1520-0493(1981)109<1671:COWAAE>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019707058&doi=10.1175%2f1520-0493%281981%29109%3c1671%3aCOWAAE%3e2.0.CO%3b2&partnerID=40&md5=aeeee3935ab9b62fa11aba08ba02a6f8","This article describes the size, intensity, trajectory, lifetime and distribution of the GATE cloud clusters of W Africa and the E Atlantic Ocean and relates their distribution to the summer climate of the region. SMS-1 infrared and visible 3 h pictures for 85 days of GATE, starting 27 June 1974, were used. It was found that over 500 clusters occurred. Size averaged 2 x 10 km; lifetime, one day.-from Authors"
"7102268722;6604075289;7004079572;7402386828;","Climate change and cloud feedback: the possible radiative effects of latitudinal redistribution.",1981,"10.1175/1520-0469(1981)038<0489:CCACFT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019678126&doi=10.1175%2f1520-0469%281981%29038%3c0489%3aCCACFT%3e2.0.CO%3b2&partnerID=40&md5=df5d7eb4f4339a56c7fc1b0afd3d5fc3","In a recent zonal atmospheric model experiment the global value of dF/dAc was different in sign than in other calculations. This difference in behaviour was traced to a latitudianl redistribution of cloud amount and height that occurred in the doubled CO2 experiment. However, when dF/dAc was evaluated at individual latitudes and then weighted globally, the value of this parameter was consistent with those found by Cess (1976) and Budyko (1974). -from Authors"
"7102486629;7004160106;","Effect of cloud-radiation feedback on the climate of a general circulation model.",1981,"10.1175/1520-0469(1981)038<2337:EOCRFO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019728595&doi=10.1175%2f1520-0469%281981%29038%3c2337%3aEOCRFO%3e2.0.CO%3b2&partnerID=40&md5=c2edb5e31c6d4a77855e435a39e8010d","Results from these experiments show significant changes in the simulated large-scale dynamical circulation of the global model. Fixed clouds acting as zonally asymmetric radiative heat sources increase the generation of eddy available potential energy (EAPE) and its conversion to eddy kinetic energy. Generation of EAPE by net radiative heating increased by 50% (0.11 W m-2) for the fixed cloud experiment. The increase due to the stationary component was much larger (c100%) but it was partially compensated by decrease due to the transient component. A substantial increase was found in the variances of the planetary-scale stationary waves and the medium-scale waves (wavenumber 6-10) of 2-7 day period.-from Authors"
"7005561168;6701652286;","The effect of a geographical cloud distribution on climate: a numerical experiment with an atmospheric general circulation model.",1981,"10.1029/JC086iC12p11995","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019656523&doi=10.1029%2fJC086iC12p11995&partnerID=40&md5=7c06bd9e36fce04b5aac9470f5e98d89","Two numerical experiments are carried out with an atmospheric general circulation model in which zonal and geographical cloud distributions are prescribed. The integrations are performed for 60 days with a GFDL model, and the last 30 days are analyzed. The geographical cloud distribution causes the increase of surface temperature over the continents by 2o-4o and leads to a decrease of surface pressure there and an increase over the oceans. The largest changes in the surface pressure up to + or -12 mbar, occur in the middle latitudes of both hemispheres. The largest differences in precipitation are observed in the tropics and over some coastal regions of North and South America. -from Authors"
"35401383000;7003573993;7004800591;7003337149;","Net incoming radiation estimated from hourly global radiation and/or cloud observations",1981,"10.1002/joc.3370010305","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019655614&doi=10.1002%2fjoc.3370010305&partnerID=40&md5=bfe1c2d8ebb44339dcaaa778c36d4f1a","From routine hourly observations reported during 5 years at one site in Denmark, empirical relations for net radiation over green grass are found. These relations give an estimate of the net radiation for the measuring site from the geographical position, local time, representative surface albedo, measured global radiation and/or total cloud cover in oktas. Cloud types are taken into account, if the reported clouds are mainly cirrus forms. This is a result of a classification of the net radiation according to cloud cover and type, i.e. a total of 90 classes. Different relations are found for different cloud covers. The derived procedure is used on another site in Denmark with another representative surface albedo. From 10 years of data, consistency is found for net radiation measurements at the two sites, allowing extrapolation of the derived net radiation procedure to other sites in Denmark. Data from the Wangara experiment (Clarke, 1971), covering 40 days, showed a similar relation for clear sky conditions, but revealed another general dependency of net radtation upon cloud cover than that found in Denmark. Therefore, relations of the kind found in this study are related to the weather and climate of the measuring site. Comparisons between net radiation estimated from the models and measurements from different sites is r2 ⋍ 0.9. Copyright © 1981 John Wiley &amp; Sons, Ltd"
"7202603816;","The CO2-climate connection. A global problem from an Australian perspective.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040277282&partnerID=40&md5=d999484e60d5d333cabbc37fba12ee11","This publication gives the position to date, including some uncertainties. It underlies four main areas which require more research: monitoring of CO2 levels in the S hemisphere; biological consequences of increasing CO2 levels; studies of cloud-radiation interaction and the role of oceans in stabilising CO2 levels; and the stability of the W Antarctic ice sheet with increasing temperature.-from Author"
"6603721096;","Trends in cloudiness in the arctic since 1920",1981,"10.1016/0004-6981(81)90358-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019389848&doi=10.1016%2f0004-6981%2881%2990358-9&partnerID=40&md5=df960d5cb29d9410ef2fa3300c924b92","Long term (~ 50 year period) trends in cloudiness in terms of number of cloudy days per month at seven Arctic stations were investigated. Trends seem to be more pronounced in the Alaskan Arctic and Greenland, and less pronounced in the Norwegian Sea. There was no evidence found for monotonic increasing cloudiness which could have been related to a growing industrial activity. © 1981."
"7402386828;7102268722;6604075289;7401785020;","Case study of feedbacks and synergisms in a doubled CO2 experiment.",1981,"10.1175/1520-0469(1981)038<1906:CSOFAS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019677676&doi=10.1175%2f1520-0469%281981%29038%3c1906%3aCSOFAS%3e2.0.CO%3b2&partnerID=40&md5=150594d6aac1a88eca323ea912266bee","A method is described for analyzing the feedback and synergistic contributions of temperature, water vapor, cloud cover, surface albedo and CO2 to the change in the radiation balance at the top of the atmosphere due to a perturbation in an annual-averaged zonal atmospheric climate model. The method provides insight into the sensitivity of the model to feedback changes in individual parameters and how each parameter influences the effects of the others.-from Authors"
[No author id available],"Proceedings of the international conference on early results of FGGE and large-scale aspects of its Monsoon Experiment, Tallahassee, 12-17 January 1981.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040845862&partnerID=40&md5=f362d9364da9f2505da05dc2a0abca18","The FGGE investigations of planetary scale meteorology, monsoons, and oceanographic effects on climate are reported. The impact of FGGE data on forecasting is assessed. Radiative heat sources and numerical modeling of the summer monsoon are treated. Cloud, circulation, and convection during the winter monsoon are covered. Monsoon onset is analyzed. Titles are abstracted here or are on our machine-readable data base. -from STAR, 20(14), 1982"
"35571076700;","Midwestern cloud, sunshine and temperature trends since 1901: possible evidence of jet contrail effects.",1981,"10.1175/1520-0450(1981)020<0496:MCSATT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019727417&doi=10.1175%2f1520-0450%281981%29020%3c0496%3aMCSATT%3e2.0.CO%3b2&partnerID=40&md5=7c8ef7b79ef6ff5bbf910a86509478a6","Records of monthly sky cover, sunshine and temperature for 1901-77 in a 10-state midwestern area were analyzed on a temporal and spatial basis to discern long-term trends and indications of shifts potentially due to added cirrus generated by jet aircraft since about 1960. The long-term trends give evidence of natural climate changes, whereas the localized shifts to more cloudiness in the central area since 1960 suggest anomalous changes related to jet-induced cirrus. -from Author"
"35588596400;","Comments on 'The steady-state format of global climate' by G.W. Paltridge.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019353886&partnerID=40&md5=56d42f6190b2a8c82d1a8ddd2703ac21","In his model, Paltridge combined the total energy balance and the oceanic energy balance of a zone with the additional assumption that the cloud cover and surface temperature of the zone are such as to maximize the vertical heat flux from the surface of the zone. This note shows that, as this further assumption cannot be applied in the vicinity of the poles, the model will eventually fail if the latitudinal resolution is increased.-after Author"
"7005027352;","Anomalous snowfall caused by Natural-Draft cooling towers",1981,"10.1016/0004-6981(81)90302-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019727032&doi=10.1016%2f0004-6981%2881%2990302-4&partnerID=40&md5=75111849a82b601aa4996528cd4f82d3","Field observations and numerical simulation are used to define circumstances under which plumes from large natural-draft cooling towers should be expected to glaciate and cause snowfall. The joint condition of temperature at the plume summit colder than -13°C and saturation deficit with respect to liquid less than 0.5 gm-3 was found to be the primary prerequisite for snowfall. If the plume merges with a cloud layer, the flux of snow may exceed the water vapor flux from the cooling tower. © 1981."
"6602199552;55547129138;6601955569;7102425376;","The role of mesoscale surface motions in the life of a convective storm in a dry continental climate.",1981,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019645310&partnerID=40&md5=3e01c5c8e08891744eac9606a2ba41db","The role of surface wind and moisture fields in the formation of a convective storm is examined in association with synoptic scale perturbations. In order to get a better understanding of the coupling mechanism between the synoptic and mesoscale phenomena in the development of convective cloud systems, a mesoscale surface network system supported by 5 cm radar was used to observe the atmosphere at short intervals in time and space. Results show that for the storm analyzed, frontal passage plays a principal role in the formation of precipitating cells. from STAR, 20(5), 1982"
"7201416271;6602089937;7005383175;","The calculation of the net radiation flux",1980,"10.1007/BF02352272","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019143519&doi=10.1007%2fBF02352272&partnerID=40&md5=a02a5d03cc70da3f360d618d6a420893","A comparison between two global solar radiation- and two net longwave radiation flux formulas applied to the calculation of the net radiation flux was made. The differences between the two global solar radiation formulas were fairly small but the ratio of the two net longwave radiation formulas varied from approximately 1.21 under cloudless conditions to 0.25 under completely overcast conditions. The calculation of the net radiation flux was primarily influenced by the calculation of the global solar radiation flux under cloudless conditions, but under overcast conditions it was largely influenced by the calculation of the net longwave radiation flux. The net radiation flux could be predicted successfully only when locally determined constants were used in the equation to calculate the global solar radiation flux and when a cloud adjustment factor was included in the net longwave radiation formulas. Evidence from the literature also indicated that, at least in humid climates, a cloud correction factor is required for the successful calculation of the net longwave radiation flux. © 1980 Springer-Verlag."
"16491876200;56264936500;","The relationship between net and global radiation over water",1980,"10.1007/BF02243837","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019141816&doi=10.1007%2fBF02243837&partnerID=40&md5=d4156376c89b9f5b8a90e1c5e9a11071","The radiation balance over a shallow lake, Lake Albert, South Australia, has been measured over the period of a year. Mean daily values of net radiation (Rn), global radiation (Q) and albedo (α) have been obtained from which linear relationships between net radiation and global radiation are determined for annual and seasonal periods. For annual period: (i) cloud free conditions Rn=0.750 Q-13.8 Wm-2 (ii) all days Rn=0.734 Q-11.9 Wm-2 Seasonal relations are determined, however they are more likely to be unique to the seasonal climate of the lake. © 1980 Springer-Verlag."
"6701652286;7102875645;","Cloud cover and climate sensitivity.",1980,"10.1175/1520-0469(1980)037<1485:CCACS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019147528&doi=10.1175%2f1520-0469%281980%29037%3c1485%3aCCACS%3e2.0.CO%3b2&partnerID=40&md5=7878511003b6bc602e24612de5b0d465","This study discusses how the sensitivity of climate may be affected by the variation of cloud cover based on the results from numerical experiments with a highly simplified, three-dimensional model of the atmospheric general circulation. -from Authors"
"7409853077;57206416522;","Effect of ice-albedo feedback on global sensitivity in a one- dimensional radiative-convective climate model.",1980,"10.1175/1520-0469(1980)037<0545:eoiafo>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019182751&doi=10.1175%2f1520-0469%281980%29037%3c0545%3aeoiafo%3e2.0.co%3b2&partnerID=40&md5=129944181ae24564cc68b81046d8c111","The effect of this feedback on global sensitivity to changes in solar constant is studied for the current climate conditions. This ice-albedo feedback amplifies global sensitivity by 26 and 39%, respectively, for assumptions of fixed cloud altitude and fixed cloud temperature. The global sensitivity is not affected significantly if the latitudinal variations of mean solar zenith angle and cloud cover are included in the global model.- from Authors"
"6602484059;7101769617;6701318848;","Characteristic law of cloud condensation nuclei and its evolution in an intertropical wet climate.",1980,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019092111&partnerID=40&md5=562579f2c582502afc6946bc98416e02","The concentration N of cloud condensation nuclei was measured in an intertropical wet climate characterized by a low anthropogenic pollution, a vegetal aerosol more particularly important in the wet season and a rich continental aerosol in dry season. The results exhibit CCN concentrations comparable to those of industrial areas of Europe and America. -from Authors"
"7101940638;7003896336;","Weather and climate needs for Lidar observations from space and concepts for their realization.",1980,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040298825&partnerID=40&md5=0ea6fac57133ba82224ee9963201c7f7","The spectrum of weather and climate needs for Lidar observations from space is discussed with emphasis on the requirements for wind, temperature, moisture, and pressure data. It is shown that winds are required to depict realistically all atmospheric scales in the tropics and the smaller scales at higher latitudes, where both temperature and wind profiles are necessary. The need for means to estimate air-sea exchanges of sensible and latent heat also is noted. A concept for achieving this through a combination of Lidar cloud top heights and IR cloud top temperatures of cloud streets formed during cold air outbreaks over the warmer ocean is outlined.-from STAR, 18(23), 1980"
"7006655968;","Radiative transfer in the cloudy and dusty atmosphere.",1980,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019144374&partnerID=40&md5=957aabdf6dc8f532c74cb783390ee286","Cloudiness is the main factor governing the planetary radiation balance; climate models should allow for cloud-radiation interactions to be properly included. Aerosols have a more subtle influence, as their role is much weaker, but their variations can induce local or global climate variations.- from Author"
"7102850632;7101685611;","On the use of earth radiation budget statistics for studies of clouds and climate.",1980,"10.1175/1520-0469(1980)037<1233:otuoer>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019214557&doi=10.1175%2f1520-0469%281980%29037%3c1233%3aotuoer%3e2.0.co%3b2&partnerID=40&md5=c79b7071e4c02efd3fca6f6952e3299a","Daily observations of albedo and outgoing terrestrial radiation derived from NOAA Scanning Radiometer measurements are used to relate cloudiness variations to regional features of the general circulation and to estimate the relative importance of the albedo and infrared effects of clouds on the net radiation balance of the earth on a regional basis. The results indicate that there are clear relationships between the variability in outgoing IR and features of the atmospheric circulation, which appears to be linked to changes in cloudiness.-from Authors"
"36943660200;7005706228;","Summer climate, microclimate, and energy budget of a polar semidesert on King Christian Island, N.W.T., Canada.",1980,"10.2307/1550513","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019202001&doi=10.2307%2f1550513&partnerID=40&md5=8100ef0306a4ca2b0100a501555c799c","This community predominates in the polar semidesert areas of the northcentral Queen Elizabeth Islands. The maritime summer climate is characterized by low temperature (2.5oC), low precipitation (43 mm), moderate average wind speed (5.9 m s-1), high relative humidity (90%), and a high incidence of cloud and fog (80%). Different suface types had only a minimal effect on the near-surface environment as a result of an aerodynamically smooth surface and only very shallow gradients in temperature and moisture from surface to atmosphere.- from Authors"
"7005211216;7003951515;25927003300;","Mini- radiocarbon measurements, chemical selectivity, and the impact of man on environmental pollution and climate.",1980,"10.1017/S0033822200009644","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019234986&doi=10.1017%2fS0033822200009644&partnerID=40&md5=74e33526985d7faafdc41ef8d74719c0","Carbonaceous gases and particles in the atmosphere have serious health effects related to aerosol inhalation and photochemical smog formation. Longer-lived tropospheric species, such as methane, may alter the stratospheric ozone layer, and the trace gases and particles may influence the Earth's climate directly through 'greenhouse' and albedo effects or indirectly through cloud nucleation. The objective of the program is to use isotopic and chemical methods of characterization to assess the strengths of the primary sources for these atmospheric contaminants, with special emphasis on the relative importance of anthropogenic and natural emissions, and consequent perturbations of the carbon cycle.-from US Govt Reports Announcements, 21, 1982"
"7102875645;6701652286;","On the distribution of climate change resulting from an increase in CO2 content of the atmosphere",1980,"10.1175/1520-0469(1980)037<0099:OTDOCC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018910639&doi=10.1175%2f1520-0469%281980%29037%3c0099%3aOTDOCC%3e2.0.CO%3b2&partnerID=40&md5=924668cae38bbb67dbcbe2cd3d202de1","A study of the climatic effect of doubling or quadrupling of CO2 in the atmosphere has been continued by the use of a simple general circulation model with a limited computational domain, highly idealized geography, no seasonal variation of insolation, and a simplified interaction between cloud and radiative transfer. The results from the numerical experiments reveal that the response of the model climate to an increase of CO2 content in air is far from uniform geographically. For example, one can identify the high-latitude region of the continent where the runoff rate increases markedly, a zonal belt of decreasing soil moisture around 42° latitude, and a zone of enhanced wetness along the east coast of the subtropical portion of the model continent. The general warming and the increase of moisture content of air, which results from a CO2 increase, contributes to the large reduction of the meridional temperature gradient in the lower model troposphere because of poleward retreat of highly reflective snow cover and large increase in the poleward transport of latent heat. The reduction of the meridional temperature gradient appears to reduce not only the eddy kinetic energy, but also the variance of temperature in the lower model troposphere. The penetration of moisture into higher latitudes in the CO2-rich warm climate is responsible for the large increase of the rates of precipitation and runoff in high latitudes of the model.A study of the climatic effect of doubling or quadrupling of CO//2 in the atmosphere has been continued by the use of a simple general circulation model with a limited computational domain, highly idealized geography, no seasonal variation of insolation, and a simplified interaction between cloud and radiative transfer. The results from the numerical experiments reveal that the response of the model climate to an increase of CO//2 content in air is far from uniform geographically. The general warming and the increase of moisture content of air, which results from a CO//2 increase, contributes to the large reduction of the meridional temperature gradient in the lower model troposphere."
"7005027352;","Effects of industrial effluents on local cloudiness and rainfall",1979,"10.1007/BF01060524","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018492571&doi=10.1007%2fBF01060524&partnerID=40&md5=6b14b8c53f6b45d8c77dc57a5ce12788","Industrial effluents alter both the microphysical properties that regulate the rate of production of precipitation and the location and strengths of density and velocity perturbations that regulate the dynamical development of clouds. Therefore, physical mechanisms exist through which industrial activities can modify local weather elements such as cloudiness and rainfall. Snow falling from large cooling tower plumes and the cloudiness spawned by heat rejection are the most obvious manifestations of this control. The extent to which industrial effluents exert control over local weather and climate remains controversial and difficult to quantify. As industrial activity becomes more concentrated, anomalous weather effects could become a problem that will require consideration when planning new facilities. This is particularly true for processes that modify the dynamical properties of the atmosphere by rejecting heat directly to the atmosphere. © 1979 D. Reidel Publishing Co."
"7202891849;7409924037;","Climatic effects of cirrus clouds.",1979,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018586730&partnerID=40&md5=bbcad9169c40df3e74f7a627e929e774","Projected increases in jet aircraft traffic may cause a large increase in cirrus cloudiness especially over Europe and North America, which may have impacts upon both the local and the planetary climate. This article reviews the influence of an increase on the global radiation balance.- L.F.Musk"
"7801415197;","Selection of LANDSAT MSS data for inventories of earth resources.",1979,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018715037&partnerID=40&md5=e5ef1290a92d4a29577fab6d20063b5e","During the selection of the most promising satellite data for multitemporal studies of earth resources, due attention should be given to the following factors: cloud cover, image quality, climate, vegetation/crops and snowcover. Co-ordination, standardisation and exchange of data of the various receiving stations, distribution centres and documentation institutes could result in a World Information System of Space Imagery.-from Author"
"13102593000;","Carbon dioxide and climate: Comparison of one- and three-dimensional models",1979,"10.1016/0160-4120(79)90012-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018589262&doi=10.1016%2f0160-4120%2879%2990012-6&partnerID=40&md5=55cd499666a2eebe799f8dbc2c7e649a","Calculations indicate that there may be a potential climatic problem due to the release of CO2 from burning fossil fuels. However there is insufficient scientific evidence to predict the impact because the available models are not well enough understood and do not take into account many feedback mechanisms. Therefore, we have calculated atmospheric temperature changes versus latitude with the simpler Manabe-Wetherald radiative-convective model and compared it to the results of their general circulation model. In addition, we have determined the changes in several physical quantities, such as cloud abundance and surface albedo, required to compensate the temperature rise related to increased CO2 concentrations. © 1980."
"6603456033;","Fundamentals of meteorology",1979,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010449914&partnerID=40&md5=875b3ac597bcc2c1ced37b6c0b35e630","This book aims to introduce college and university students to meteorology and climatology; it is designed primarily for those with little training in mathematics, physics or chemistry with a view to helping them perceive the role of the atmosphere in human affairs. After an introductory chapter, there follows chapters on: Atmospheric composition and structure; energetics of the atmosphere; the winds; atmospheric stability and vertical motions; planetary patterns of air motions; air masses, fronts, and cyclones, clouds, rain and snow; severe storms; atmospheric optics and acoustics; climates of the earth; and applications. The appendices include conversion factors, humidity tables, selected climatological data and sources of further information. L. F. Musk"
[No author id available],"Earth radiation budget science, 1978: introduction.",1978,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040276442&partnerID=40&md5=71c915ee8db88ec9dcb46fcc925b0b23","An earth radiation budget satellite system (ERBSS) is planned in order to understand climate on various temporal and spatial scales. The system consists of 3 satellites and is designed to obtain radiation budget data from the earth's surface. Among the topics discussed are climate modeling and climate diagnostics, the applications of radiation modeling to ERBSS, and the influence of albedo clouds on radiation budget and atmospheric circulation. - from STAR, 17(23), 1979"
[No author id available],"Climate modeling.",1978,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040276989&partnerID=40&md5=d766dc919a26b423c25c343a9a6ce2cc","The requirements for radiation measurements suitable for the understanding, improvement, and verification of models used in performing climate research are considered. Both zonal energy balance models and 3 dimensional general circulation models are considered, and certain problems are identified as common to all models. Areas of emphasis include regional energy balance observations, spectral band observations, cloud-radiation interaction, and the radiative properties of the earth's surface. -from STAR, 17(23), 1979"
"56186798600;16216273400;7401979213;36615870000;7006325825;","Airborne electrical and microphysical measurements in clouds in maritime and urban environments",1978,"10.1016/0004-6981(78)90355-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018144291&doi=10.1016%2f0004-6981%2878%2990355-4&partnerID=40&md5=f57b2ed93de21efb5a9ac218087dcd6d","A study by Khemani and Ramana Murty (1973) has indicated significant increases of rainfall downwind of the urban industrial complex at Bombay during the period of increased industrialisation. In order to understand the physical processes responsible for the observed increases in rainfall, aircraft measurements of cloud electrical and microphysical parameters and of free-air temperatures were made in the maritime (upwind) and urban (downwind) regions at Bombay. The study has pointed out differences in the electrical and microphysical state of clouds in maritime and urban environments. In the maritime clouds the electric field was both positive and negative and the cloud droplet charges were positive. In urban clouds the electric field was negative and the droplet charge was also negative. The cloud condensation nuclei and the total measured droplet concentrations were higher in the urban environment. In urban clouds the droplet spectra showed a multimodal distribution and in maritime clouds it was unimodal. Also, the concentration of large droplets of diameter 50 μm and above, and the integrated cloud droplet liquid water content were more in the urban environment. The tail of the droplet spectra extended to higher sizes in urban clouds. The free air temperature in the urban environment was higher by about 1°C. © 1978."
"57216016796;","Carbon dioxide and climate. Too much heat clouds debate",1978,"10.1016/0301-4215(78)90005-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018231188&doi=10.1016%2f0301-4215%2878%2990005-8&partnerID=40&md5=a7f6aecdd92aba367a8e8512a538ba8d","A growing awareness of the possibility of a carbon dioxide 'greenhouse effect' acting to warm the Earth unpleasantly has been seized on in some quarters as an argument against increased use of fossil fuels and, by implication, in support of a massive nuclear programme. These issues need to be set in a proper climatological perspective, comparing the possible extent of anthropogenic influences on climate with natural fluctuations, and should also take some account of mankind's technological capability to cope with the problem, once carbon dioxide has been recognized as a 'pollutant'. Such a viewpoint shows that while the carbon dioxide problem is real and has important implications for energy policy, neither the problem nor the policy implications are the same as those pressed upon us by the fossil fuel doomsters. © 1978."
"7101740594;","The radiative effect of atmospheric pollution: Latitudinally dependent radiation calculations including cloud contribution",1978,"10.1016/0004-6981(78)90007-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018083819&doi=10.1016%2f0004-6981%2878%2990007-0&partnerID=40&md5=5b043746a4ed85531d36a459d0edef2b","In this paper, we have developed a radiation scheme based on the discrete-ordinate method into which a comparatively thick cloud layer can be incorporated for inhomogeneous aerosol atmospheres. Using the above radiation scheme, we performed calculations of the effect of clouds upon the inhomogeneous aerosol atmospheres, including the effects of optical depth, vertical distribution and extent of cloud layer. Calculations were also carried out for the local albedo, total absorption and diffuse transmission at each latitude belt, considering a land-sea distribution and a latitudinal variation of cloudiness, for six realistic model aerosol atmospheres. A 0.50 μm flux of the solar radiation is used for this study. The main conclusions of the radiative calculations may be summarized as follows. 1. (1) For the same optical thickness, a densely stratified cloud layer within the lower aerosol troposphere is apt to reflect the solar radiation much less effectively than other stratifications of cloud. If cloud layers are present at higher levels, absorption of solar radiation within the atmosphere would decrease considerably. 2. (2) Cloudiness and/or cloud thickness play a very important role upon the global heat balance problems and should never be ignored in studying the effects of increased aerosols upon climate, because contrary to the cloudless condition, heating of the earth-atmosphere system would tend to be induced by an increase of aerosols in the atmosphere where clouds are present. Because of the high surface albedo, an increase of aerosols reduces the reflectivity at the snow-covered high latitude belts, regardless of the effects of cloud. 3. (3) By the perturbation of adding aerosols into the troposphere or the stratosphere the diffuse transmission increases at the ground level. However, this effect is offset by the direct exponential attenuation of solar flux, and as a result, the total solar radiation reaching the ground is somewhat reduced. 4. (4) The absorption of solar radiation within the atmospheres due to aerosols would reach near 10% of incident solar flux for injection of a fairly massive amount of aerosols into the troposphere or the stratosphere due to great volcanic eruptions or man's impact. © 1978."
"6504793395;","General information on the Arabian peninsula: climate.",1978,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018210245&partnerID=40&md5=1b45ef641f002921196a1fac83f25923","Precise records are widely scattered, and of short duration. Only 23 stations provide adequate data for a land area of 3 000 000km, and the analysis covers only 8 yr. Summer temperatures (shade) exceed 48oC in central Arabia, with a mean ranging from 27.5 - 36.8oC. during winter mean monthly temperatures at inland stations range from 4.5oC to 20oC, but on the Red Sea range from 18.6oC - 26.9oC, and on the Arabian Gulf from 11o - 22.2oC. Rainfall variability is extremely high. Mean annual cloud cover is less than 20% inland and 20 - 40% along the Arabian Gulf coasts, and evaporation greatly exceeds precipitation. Solar radiation is therefore very high (409-663 calories per squate cm. per day). Prevailing wind directions for selected stations are tabulated on a monthly basis. -J.C.Doornkamp"
"6603839217;","The steady‐state format of global climate",1978,"10.1002/qj.49710444206","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987111905&doi=10.1002%2fqj.49710444206&partnerID=40&md5=a9ef20823daca54e9239cbcc22ef6888","It can be proved for certain small‐scale convective heat transfer processes that the preferred steady‐state mode is one of maximum entropy production. The constraint is more or less equivalent to one of maximum kinetic energy dissipation or of maximum convective heat transport. Evidence is accumulating that the same constraint may apply on the much larger scale of the earth‐atmosphere system. The concept is accepted as the basis of a purely thermodynamic model of the mean annual global climate. The model allows a prieri calculation of the broad‐scale geographic distributions of cloud, surface temperature, horizontal energy fluxes in the ocean and in the atmosphere, net radiant energy inputs, etc. The agreement with observation strongly supports the basic concept. It suggests also that, to the extent allowed by the degrees of freedom in the dynamics, the partition of atmospheric and oceanic energy flow is determined by a requirement to equalize the local dissipations in the two media. Copyright © 1978 Royal Meteorological Society"
"13102593000;57214388942;","The direct effects of chlorofluoromethanes on the atmospheric surface temperature",1978,"10.1016/0004-6981(78)90294-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018120126&doi=10.1016%2f0004-6981%2878%2990294-9&partnerID=40&md5=78976f43ce64e581fdc6ef7b44e31578","The two most widely used chlorofluoromethanes (CFCl3 and CF2Cl2) uniformly distributed at a constant mixing ratio have been added to our version of the Manabe-Wetherald radiative convective model (which includes globally averaged values for solar radiation, carbon dioxide, water, water clouds, airborne particles and the reflectivity of the earth's surface) to calculate the steady state surface temperature change. Our calculations indicate an essentially linear increase of 0.15 K/ppbv of total CFM with particles included and 0.19 K/ppbv without particles. The amount of CFM now in the atmosphere is estimated to have caused a 0.05 K increase in the earth's surface temperature. © 1978."
"24443137100;","Atmospheric water vapour of extraterrestrial origin: a discussion of its possible role in Sun-weather relationships",1978,"10.1016/0021-9169(78)90089-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0004665955&doi=10.1016%2f0021-9169%2878%2990089-2&partnerID=40&md5=e7ae5de1c8878f85864940c6ea130668","This paper discusses in detail the speculative suggestion that the influx of extraterrestrial hydrogen to the Earth's atmosphere constitutes a significant variable source of atmospheric water vapour (sometimes called 'solar rain' or 'extraterrestrial rain') which can be invoked to explain Sun-weather relationships. The continual influx of solar-flare protons with energies in the range 1-100 MeV, which penetrate down to the mesosphere or upper stratosphere, makes a negligible contribution to the normal water vapour concentration at these altitudes. During the most intense solar-proton event yet recorded (August 1972) this solar-flare contribution to atmospheric humidity amounted to no more than 2 parts in 109. Moreover, the long-term average influx of solar-flare protons, or galactic-cosmic-ray protons, has been totally inadequate to produce an appreciable change in the concentration of atmospheric water vapour. The continuous influx at the magnetospheric clefts of solar-wind protons with a mean energy of about 1 keV, which cannot penetrate below 150 km and hence cannot form water vapour directly, only constitutes a highly-localized reduction, or reversal, of the global efflux of hydrogen atoms from the Earth's atmosphere: a similar conclusion holds for auroral protons (∼10keV). At the present time the influx of interstellar hydrogen atoms is trivial compared with the global efflux of terrestrial hydrogen atoms. However, the influx of interstellar hydrogen could be greater than the efflux of terrestrial hydrogen if the Solar System encountered a dense interstellar cloud, but the atmospheric implications of such a large influx of interstellar hydrogen require further consideration. Apart from this one possible exception, which could only be advanced as a tentative explanation for very long-term (∼106y) changes of climate, the hypothesis that Sun-weather relationships can be attributed to atmospheric water vapour of extraterrestrial origin is untenable. © 1978."
"6602439181;57217889265;","Climate of the drift-ice zone",1977,"10.1080/10889377709388611","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910861210&doi=10.1080%2f10889377709388611&partnerID=40&md5=3a7d8259150e08d80b74c687d1eaec38","The article discusses climatic characteristics in the drift-ice zone, including circulation conditions, radiation regime, temperature and pressure fields, cloud micro-structure and the climate of the free atmosphere. The significance of climatic studies in this region is emphasized in connection with plans for resource development and navigation along the north coasts of the Soviet Union. A greater need is seen for quantitative evaluation of heat and water exchange within the region and along its outer boundary. © 1977 Taylor and Francis Group, LLC."
"35571076700;","ACCIDENTAL AND PLANNED WEATHER MODIFICATION IN ILLINOIS",1977,"10.1111/j.1752-1688.1977.tb02088.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980246904&doi=10.1111%2fj.1752-1688.1977.tb02088.x&partnerID=40&md5=ec7fbcd556dab927cc1c01257314daab","ABSTRACT: Weather modification, both planned by man and that accidentally produced by man, has been under intensive study in Illinois for ten years. Most everyone in Illinois and the Midwest is living in a climate that now is modified inadvertently from its natural state. State atmospheric scientists have tackled weather modification through a series of interrelated studies beginning with climatic studies (to establish the background), experimental design studies, experimental field studies to verify changes and their causes, and finally socio‐economic and environmental studies to measure the impacts of weather modification. Studies at St. Louis show that the city acts as a trigger of summer clouds and rainfall leading to 4 to 6 summer days with 3 cm or more rain somewhere just east of the city. Power plants and jet aircraft also accidentally produce climatic changes. A focus on planned weather modification has been on the design of needed midwestern experiments in rainfall enhancement and hail suppression including the societal and environmental impacts. Copyright © 1977, Wiley Blackwell. All rights reserved"
"7003552210;","The energy balance of an exterior window surface, Inuvik, N.W.T., Canada",1977,"10.1016/0360-1323(77)90022-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042007252&doi=10.1016%2f0360-1323%2877%2990022-1&partnerID=40&md5=35eba8732e3aa675dedd77d807cbf419","This paper examines the energy loss of an exterior window surface during the month of January, 1975, in Inuvik, N.W.T., Canada. Radiative exchanges (L*) were measured and the energy loss through the window was calculated (QF). Since an energy balance exist at the exterior window surface, a heat transfer coefficient (h) was determined by residual: h=(QF-L*)/(Ts-Ta). Calculated values for the heat transfer coefficient compare favourably with those of other studies. The atmospheric controls (i.e. wind speed and cloud cover) on radiative and convective heat losses and their influence on urban climate are discussed with respect to the observational data. © 1977."
"7601483245;","Potential weather modification from cooling tower effluents at conceptual power parks",1977,"10.1016/0004-6981(77)90184-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0017422232&doi=10.1016%2f0004-6981%2877%2990184-6&partnerID=40&md5=c428597013a50aeaa720fadc1df809a2","A numerical model for multiple plumes is developed to study the enhanced convection of merged plumes from a cluster of cooling towers at a conceptual power park. The model is based on the equations of motion for a quasi incompressible fluid derived from the laws governing the change of momentum, the first law of thermodynamics, and the conservation of mass. The microphysical processes are simplified in the model by a parameterization approach similar to the work of Kessler (1969) with the assumption that the droplet size distributions in the cooling tower plume are the same as those of cooling tower drift measured near the top of cooling towers. The numerical model is employed to simulate the merged plume convection from clusters of (up to 40) natural draft cooling towers, where each tower serves to dissipate 2400 MW of waste heat. It was found that the plume rise from 40 towers is predicted to be approximately 360% and 130% of that from a single tower for an average July afternoon and average January morning sounding, respectively, taken in the Louisiana area if the towers are arranged in a near square grid and spaced at 300 m apart. However, it is not uncommon to predict an induced convective cloud developing over 4000 m in height from more than 5 towers in a group for an individual afternoon sounding in the southeastern United States. Comparison of the predicted precipitation using Kessler's microphysical parameterization with Marshall and Palmer's (1948) drop size distribution and the similar approach with available observed droplet size distribution from cooling tower drift is also made. The model predictions are in good agreement with observations at existing power plants up to 3000 MWe generating capacity. © 1977."
"7006608787;","A remarkable protalus rampart complex in Wester Ross",1976,"10.1080/00369227608736346","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0006657462&doi=10.1080%2f00369227608736346&partnerID=40&md5=931e8e50ff5f72cc50939b0dc405edf5","A massive pile of rock debris, much of it composed of blocks 1-5m long, accumulated in the Lateglacial at the foot of a snow bed in Wester Ross. The accumulation is a kilometre long and up to 55m high and the volume of debris in it is c. 600,000 m3. It implies that the bedrock faces that supplied it retreated some 17m in about 750 years. Certain aspects of the debris mass permit climatic inferences: they suggest that snow-bearing winds from the south-east were important and that a cool, very cloudy climate was succeeded by a very cold climate with less cloud. © 1976 Taylor &amp; Francis Group, LLC."
"24600221800;","Monitoring the global climatic impact of direct heat addition associated with escalating energy use",1976,"10.1016/0360-5442(76)90069-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0017249716&doi=10.1016%2f0360-5442%2876%2990069-4&partnerID=40&md5=37de0ac51b7d004bd1829524528ab1bc","Using Budyko's overall heat-balance equation, we estimate that direct heat addition associated with worldwide energy use in the year 2050 will be responsible for a mean global temperature rise of 0.27 °C at a 20 kwt per capita energy consumption for a world population of ten billion people. The corresponding temperature rise between 15 and 60 °N is estimated to be 0.44 °C. If per capita energy consumption during the year 2050 is reduced to 5 kw, (i.e. about one half of U.S. consumption in the year 1970), the estimated temperature rise for the 15-60 °N latitudinal belt will be about 0.11 °C and therefore still not negligibly small. A program for monitoring the global climatic impact of escalating energy use involves precise monitoring of the following quantities: 1. (a) the solar constant 2. (b) the effective earth-atmosphere albedo 3. (c) the net (long-wavelength) radiant energy emitted from the earth-atmosphere system. Both the effective albedo and the (long-wavelength) radiant energy emitted from the earth-atmosphere system will depend on the nature and size of particulate concentrations in the atmosphere, on molecular emitters (especially CO2 and H2O), cloud cover, and on the radiative-convective circulation pattern. A satellite observation program that is closely integrated with ground-based and atmospheric measurements and with a detailed program of theoretical analysis will be needed for more precise predictions of inadvertent climate changes and for developing the means to effect desirable global climate controls. © 1976."
"7003367957;","Estimating grass minimum temperatures from screen minimum values and other climatological parameters",1976,"10.1016/0002-1571(76)90071-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-27944483554&doi=10.1016%2f0002-1571%2876%2990071-6&partnerID=40&md5=001f0ce72b1c9e34f4c23a23c6d4307b","Differences between night-time screen and grass minimum temperatures in a standard climate station were related to general weather parameters, using stepwise multiple linear regression and correlation techniques. Opacity (cloud cover) and wind speed were found to be the most significant parameters in regression, explaining up to 74% of the variation in the differences in temperature between the screen and grass thermometers. There is evidence that absolute air temperature and dew-point depression may, on some occasions, significantly influence the screen to grass minimum temperature difference. The relationships were relatively conservative from season to season and year to year. Wind was not an important parameter at speeds less than 1.8 m sec -1. At low wind speeds the minimum 2-h average opacity was better correlated with the dependent variable than were either longer or shorter opacity averages. In independent data tests, the average screen to grass minimum temperature difference for 82 cases was estimated within 0.1°C of the measured value. Standard error of estimates ranged from 1.5 to 2.0°C. Attempts to obtain significant correlations for weather stations located on slopes in hilly terrain were unsuccessful. © 1976."
"6602728596;7005256983;16512872100;","The short-term influence of various concentrations of atmospheric carbon dioxide on the temperature profile in the boundary layer",1975,"10.1007/BF01592922","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250395019&doi=10.1007%2fBF01592922&partnerID=40&md5=a6e45788888576db843656541f04de6e","A radiative-conductive model is constructed to study short-term effects of various carbon dioxide concentrations on the atmospheric boundary layer for different seasons. The distribution of the exchange coefficient is modeled with the aid of the KEYPS formula. Infrared radiation calculations are carried out by means of the emissivity method and by assuming that water vapor and carbon dioxide are the only radiatively active gases. Global radiation is computed by specification of Linke's turbidity factor. It is found that doubling the carbon dioxide concentration increases the temperature near the ground by approximately one-half of one degree if clouds are absent. A sevenfold increase of the present normal carbon dioxide concentration increases the temperature near the ground by approximately one degree. Temperature profiles resulting from presently observed carbon dioxide concentration and convective cloudiness of 50% or less are compared with those resulting from doubled carbon dioxide concentrations and the same amounts of cloud cover. Again, it is found that a doubling of carbon dioxide increases the temperature in the lower boundary layer by about one-half of one degree. The present results are obtained on the basis of fixed temperature boundary conditions as contrasted to the study of Manabe and Wetherald (1967). Howeve, the conclusions are not addressed to global climate change, but to the distribution of the temperature of the air layer near the ground. © 1975 Birkhäuser Verlag."
"7005296135;","Transport of aerial spray, III. influence of microclimate on crop spraying",1975,"10.1016/0002-1571(75)90034-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0016447782&doi=10.1016%2f0002-1571%2875%2990034-5&partnerID=40&md5=aaf7c2ea37dbcecc869a52a97ae801b3","Based on a model of aerial dispersion of spray clouds released from aircraft, criteria are given for choosing droplet sizes and flying heights in practical crop-spraying situations. There are advantages in using sprays composed of small droplets; micrometeorological measurements over cotton suggest that maximum droplet diameters should be about 60 μm. © 1975."
"6603839217;","Global dynamics and climate ‐ a system of minimum entropy exchange",1975,"10.1002/qj.49710142906","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981674399&doi=10.1002%2fqj.49710142906&partnerID=40&md5=fbf590a54738a843392ed5d1e6efb60e","It is found that the mean meridional distribution of temperature, cloud cover and meridional energy flux can be predicted with extraordinary accuracy by application of a simple minimum principle to a multi‐box model of the globe which contains no direct specification of the system dynamics. The minimized quantity is related to the global net rate of production of entropy. It is the sum over all latitude zones of the ratio of net radiant energy input to the effective emission temperature of the zone. The result suggests that global dynamics is something of a passive variable which alters so as to satisfy a condition akin to minimum energy dissipation. Copyright © 1975 Royal Meteorological Society"
"7003830856;","Pollution and the planetary albedo",1974,"10.1016/0004-6981(74)90004-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0016265165&doi=10.1016%2f0004-6981%2874%2990004-3&partnerID=40&md5=099a4aa16647004ae2b82e28f21197c2","Addition of cloud nuclei by pollution can lead to an increase in the solar radiation reflected by clouds. The reflection of solar energy by clouds already may have been increased by the addition of man-made cloud nuclei. The albedo of a cloud is proportional to optical thickness for thin clouds, but changes more slowly with increasing thickness. The optical thickness is increased when the number of cloud nuclei is increased. Although the changes are small, the long-term effect on climate can be profound. © 1974."
"7003912732;7401844779;","EXPERIMENTAL STUDY OF THE URBAN AEROSOL STRUCTURE AND ITS RELATION TO URBAN CLIMATE MODIFICATION.",1974,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347659382&partnerID=40&md5=16bdad8777afafe12cfd6013f2a010ec","OBSERVATIONS OF THE URBAN AEROSOL USING ACTIVE AND PASSIVE REMOTE SENSORS, AS WELL AS IN-SITU INSTRUMENTS, WERE CONDUCTED BY SRI DURING THE 1971, 1972, AND 1973 METROMEX FIELD PROGRAMS.EXAMPLES OF THE DATA AND THEIR INTERPRETATION ARE PRESENTED, INCLUDING I< A COMPARISON OF THE URBAN MIXING DEPTH AS OBSERVED BY LIDAR AND ACOUSTIC SOUNDER; II< MOBILE LIDAR STUDIES OF URBAN-RURAL DIFFERENCES IN MIXING DEPTH, CLOUD DEVELOPMENT, AND TEMPERATURE; AND III< MULTIWAVELENGTH SUNPHOTOMETER STUDIES OF PARTICULATE OPTICAL DEPTH AND SIZE DISTRIBUTION.PLANS FOR FUTURE RESEARCH ARE BRIEFLY INDICATED.%A<"
"7003935733;7006033356;7401935516;","Techniques for air pollution observation from space",1973,"10.1007/BF00655697","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0015700043&doi=10.1007%2fBF00655697&partnerID=40&md5=13b9b91d613cbea872b4398e2ade91c5","Air pollution problems of a scale larger than the point monitoring problem lend themselves to space observational techniques. Examples of these large scale problems are those associated with changes in the global background of gases and aerosols; potential stratospheric pollution resulting from SST operations; regional sources, pollution episodes, and large scale diffusion; and effects of pollutants on climate. These problems are discussed and observational requirements are specified. Possible remote sensing techniques for satellite monitoring are described. These include monitoring of pollutant gases and particulates by means of their absorption and scattering of radiation in both the solar spectrum range and terrestrial emission spectrum range. A discussion of potential difficulties includes the atmospheric and surface background problems, the temperature sensitivity problem in the terrestrial spectrum range, the band overlap problem, and the cloud interference problem. Recent observations from satellites and balloons are reviewed. It appears that except for H2O, and, perhaps, O3, measurements of the vertical profiles of atmospheric pollutant gases and aerosols from satellites will be extremely difficult. On the other hand, measurements of the total amounts (in a vertical column) of pollutant gases and aerosols do appear feasible. © 1973 D. Reidel Publishing Company."
"7003639980;6701882465;24490551300;35501654900;","Climatic fluctuations during the late Pleistocene",1973,"10.1130/MEM136-p317","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880215843&doi=10.1130%2fMEM136-p317&partnerID=40&md5=bb2576f9bfdf0b354d8e593713dd46d3","The oxygen-isotope ratio in polar snow is determined mainly by the temperature of formation of the precipitating clouds. A continuous core 1,390 m long through the ice sheet at Camp Century, Greenland, reveals a climatic record, inferred from those ratios, spanning possibly the last 100,000 yrs. The depth-age relationship of the core is calculated from present ice-flow patterns and simple assumptions; the paleoclimatic data are interpreted from the analysis of oxygen-isotope-ratio measurements on nearly 7,000 individual samples cut from the core. The ice-core record reveals that the Wisconsin Stage started 73,000 yrs B.P. Many perturbations of the oxygen-isotope ratios are observed within the Wisconsin Stage that agree with climatic oscillations dated by radioactive methods. An 11 %o shift in the 0 isotope data shows that the Wisconsin Stage ended very rapidly, within a 2,500 yr interval, at about 13,000 yrs B.P. Spectral analyses of the data show oscillations with periods of 78, 181, 400, and 2,400 yrs."
"6701774369;16523467900;","The role of dew in the seasonal moisture balance of a summer-dry climate",1973,"10.1016/0002-1571(73)90057-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0011890182&doi=10.1016%2f0002-1571%2873%2990057-5&partnerID=40&md5=8321613c2d644b7048ddc3d3d7873efa","This study investigates the role of dew in the moisture balance of a summer-dry climate. Dew was measured by means of the optical technique employing Duvdevani dew blocks during three summer months and one fall month in 1970. Results were compared with rainfall and potential evapotranspiration. Dew amounted to 12-14% of normal monthly rainfall in mid-summer. In the unusually dry year of 1970 it reached 154% of the rainfall in August. Dew was seen to increase with the number of clear nights and, thus, increased as clouds and precipitation decreased. Although dew was an available source of evaporative moisture until approximately 09h30 on the morning after a clear night, its total was only about 2% of monthly potential evapotranspiration. The amount of dew increased outward from a vertical forest edge as longwave cooling and wind effects increased. © 1973."
"6602822646;","Paleohydrologic implications of some Pluvial Lakes in Northwestern New South Wales, Australia",1973,"10.1130/0016-7606(1973)84<3663:PIOSPL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874833139&doi=10.1130%2f0016-7606%281973%2984%3c3663%3aPIOSPL%3e2.0.CO%3b2&partnerID=40&md5=232977a7a008f3f2fb37aad651fe0b55","Some internally draining lakes in northwestern New South Wales, Australia, are contained in structural basins but owe their lack of external outlets to arid climate. Former high lake shorelines are defined in part by precipitated crusts or by deltas. Radiocarbon dating, although as yet less than satisfactory, suggests that the high lake stands occurred not later than about 14,500 B.P. They may eventually be correlated with lacustrine episodes that, elsewhere in inland New South Wales, occurred in the range 23,500 to 15,500 B.P. Whether or not the lakes under discussion existed at the time of maximum cold is uncertain; but they were indubitably associated with low paleotemperatures. Reconstruction of former temperatures involves little or no controversy. Use of paleotemperatures to reconstruct former evaporation rates produces results that stand up well to checking. Manipulation of the equilibrium equations for closed lakes produces precipitation equations that involve evaporation, area ratio between lake and rest of basin, and evapotranspiration. Empirical studies and some paleohydrologic work supply values or ranges of evapotranspiration and basin loss. Even in the lowest observed or estimated range of evapotranspiration, the precipitation equations indicate former precipitation about 50 percent greater than that of today. Calculation of evapotranspiration rates for former conditions of radiation and temperature and for a range of sunshine incidence, and entry of these rates into the precipitation equations, show that very low values of sunshine incidence would be required to drive calculated precipitation down to, or below, today's levels. That is to say, any hypothesis that the former high lake stands were associated with reduced precipitation demands inordinately low rates of evapotranspiration, plus a combination of reduced precipitation with inordinately high cloudiness. © 1973 Geological Society of America."
"7005599540;57197512227;","A note on estimating the direct and diffuse components of global radiation",1972,"10.1007/BF02243175","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041698830&doi=10.1007%2fBF02243175&partnerID=40&md5=1c8fe3ae7e09af3e653e483696d91769","Empirical methods for estimating the direct and diffuse components of known global radiation are examined in detail and are tested with data from Australia, Papua New Guinea, India, southern Africa and the Stanley Islands. Significant differences are observed between relations deduced in this study and those reported by Liu and Jordan as deduced from temperate zone data in the northern hemisphere. A simple model for atmospheric attenuation has been developed which produces a common basis for the two empirical estimation methods. In this model diffuse radiation is related to the depletion of the direct beam in the atmosphere by a forward scattering function coefficient (K), whose value for different regions, climates and important cloud categories is discussed. Theoretical curves are generated relating diffuse and direct radiation to total global radiation for several values of the coefficient K. © 1972 Springer-Verlag."
"6602428440;","A study of biotropism of climate in two Canadian cities",1972,"10.1007/BF01810282","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0015329171&doi=10.1007%2fBF01810282&partnerID=40&md5=ec3b19a245a29f0530b36f372c755aa1","Climatic trends and effects on human health due to urbanization/industrialization of two Canadian cities during the last 30 years have been investigated. It was found that the frequency of thunderstorms, fog and smoke/haze days, cloud amount and dew point increased due to urbanization. Trends in mortality due to chronic bronchitis and neoplasm of the trachea lung and bronchus suggest a positive effect of meteorological parameters. © 1972 Swets & Zeitlinger N.V."
"7401904068;","Atmospheric particles and climate: can we evaluate the impact of man's activities?",1972,"10.1016/0033-5894(72)90068-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-29144474664&doi=10.1016%2f0033-5894%2872%2990068-3&partnerID=40&md5=9defd58ef43b62c6e4b7425b60e9eb5d","The equilibrium temperature of the Earth is maintained by a balance between the unreflected part of the incoming solar energy, which is absorbed by the Earth-atmosphere system, and the outgoing long-wave radiation escaping from the Earth to space. It has long been suspected that suspended atmospheric particles (aerosols) might affect this balance, primarily by affecting the albedo or reflectivity of the Earth, thereby altering the amount of solar energy absorbed by the Earth. In light of some recent evidence suggesting the existence of an increase in atmospheric particle concentrations (presumably related to man's activities), the need for development of adequate numerical models to study this problem is apparent. Recent numerical models studying the effect of particles on climate are often based on multiple scattering radiative transfer calculations, and use global averages for particle concentrations and optical properties. By contrasting certain existing models, some major problems in modeling studies that attempt to answer the question of the effects of increased atmospheric particles on climate can be illustrated. It will also be apparent that another uncertainty in the results of such studies arises from a lack of adequate observed input data on the geographic and vertical distributions of particle concentrations and their optical properties. Furthermore, a model that could realistically simulate the impact of increasing atmospheric particle concentration on climate must eventually include the simultaneous coupled effects of all the important atmospheric processes, such as fluid motions and cloud microphysics, in addition to the radiative transfer effects. Current modeling studies already do predict that increases in particle concentrations could have a significant effect on climate. Now, it remains for us to develop the kinds of refined models needed to verify or deny these predictions. © 1972."
"55123992900;7202132222;","Mapping of mangrove and perpendicular-oriented shell reefs in southeastern Panama with side-looking radar",1972,"10.1016/0031-8663(72)90001-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0015490176&doi=10.1016%2f0031-8663%2872%2990001-4&partnerID=40&md5=d01f166003b8115859cda03f29890967","The paper demonstrates the utility of radar imaging systems in cloud-cover plagued areas for mapping mangrove swamps and two related but seldom reported environmental features, non-vegetated zones and shell reefs. Discrimination between black and red mangrove is illustrated. The presence of these three tidal-zone features suggests that certain physical processes are or were active in the study area. More specifically, mangrove suggests tropical temperatures, fine-grained alluvium, and a low-energy environment. The non-vegetated zones delimit the position of spring tides and indicate a seasonal dry climate and a large tidal range. Shell reefs, which require a firm substratum, may demarcate previously abandoned distributary channels and/or indicate near-shore circulation patterns. © 1972."
"16531327000;","Weather modification and the hydrologic cycle",1970,"10.1007/BF02243023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250476935&doi=10.1007%2fBF02243023&partnerID=40&md5=280a12d7243e104f6d42d40879a27b25","The effects on the hydrological cycle observed with cloud seeding and concentration of land water for public, industrial and agricultural use are discussed. The further consequences and probable results of these activities on weather and climate are analyzed so as to invite attention to and initiate researches of a precipitation augmentation possibility not widely considered at present. The conclusion is that current practices interfere with natural processes in some way while much partial information already point to a more rational procedure for precipitation initiation than cloud seeding. Increased precipitation could be achieved by intensification of local hydrologic cycles modifying the soil surfaces and evaporating waste water from those surfaces. An obvious but actually neglected effect of air pollutants should be taken into account when making preparations for precipitation initiation because they may cause a daily variation of the state of the troposphere in some cases. © 1970 Springer-Verlag."
"7101828348;7402797420;6604054653;","Fluorescent tracer studies of pollutant transport in the san francisco bay area",1970,"10.1080/00022470.1970.10469447","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0014837797&doi=10.1080%2f00022470.1970.10469447&partnerID=40&md5=1b759312f186f2492d53ea0400e3668a","To simulate the transport and diffusion of airborne contaminants across a metropolitan region, point-source releases of fluorescent tracer material were made near various urban centers and some 50 samplers were arrayed in expected downwind directions. The effects of land-water, hill-valley, and urban-rural differences on airflow and diffusion were observed in their existing interrelationships during these experiments. Since the tracer could be assessed with high sensitivity over great distances, tracer results provided a quantitative indicator of pollutant dispersion across an extensive metropolitan complex. From July 1967 through June 1968, the test series included typical seasonal weather patterns, with emphasis on those conducive to the travel and accumulation of pollutants. In each test about 15 kilograms of tracer material were released during two-hour periods, and significant dosages were found at downwind distances up to 80 kilometers. All tests were conducted during daylight hours, to coincide better with the oxidant-type pollution important in this region. Dispersion characteristics showed much greater complexity than predictable from classical models, thus limiting the applicability of such models in this region. Built-up urban areas increased the initial dispersion rates of tracer clouds, and travel over water tended to decrease them. Hilly terrain resulted in increased dispersion, but channeling associated with such terrain caused locally higher concentrations. The complex horizontal dosage patterns obtained did confirm previously observed airflow patterns as aids in predicting pollutant distributions. © 1970 Taylor & Francis Group, LLC."
"6506348530;6508236772;","A mesoclimatological classification system for air pollution engineers",1969,"10.1080/00022470.1969.10466520","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0014537029&doi=10.1080%2f00022470.1969.10466520&partnerID=40&md5=f3a2795febfb0ebdc3b90f91b38d8ec1","A method of deriving 3 air pollution potential indexes based on selected climatic data and meso-climate topographic factors have been developed, though not yet adequately field tested, for use by engineers in choosing between alternate factory sites. Three indexes, one for general air pollution, one for photoreac-tive air pollutants, and one for fog-reactive air pollutants, the latter two based on the first one plus sunshine and humidity factors respectively, are presented. These indexes vary with locations, not with air pollutants or time. The first index, called the GSI (General Stagnation Index) is based on a series of national maps which present a variety of climatic parameters pertinent to air pollution potential for the mid-season months of July and October. These maps, useful by themselves, have been derived from climate records from 129 Weather Bureau airport stations and from radiosonde data. The parameters used include wind speed percentages in the 0-3 and 0-12 mile/hr categories, cloud cover percentages, a nighttime stagnation factor, and a vertical ventilation factor. The GSI provides a means of estimating the additional climatic stagnation that occurs in topographically sheltered areas due to width, height and area of the valley (if present), further modified by meso- and micro-climatological factors, such as angle and aspect of slope, solar intensity, sky cover and character of surface. Specialized wind speed summaries from a variety of topographical configurations in West Virginia resulted in a graph which may be helpful in such calculations for any sheltered location from a nearby measurement of relatively unrestricted air flow such as are typically measured at the Weather Bureau airport stations.Weaknesses and possible uses of the various stagnation indexes are discussed. © 1969 Air & Waste Management Association."
"57217572485;","Solar radiation on the south coast of England",1968,"10.1002/qj.49709440115","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978600335&doi=10.1002%2fqj.49709440115&partnerID=40&md5=8032854681b73785124f41addf8f05c7","Three years' data of incoming measured solar radiation at the Glasshouse Crops Research Institute are used to assess the radiation climate of the south coast. Radiation in both summer and winter is higher than at other stations in this country; this is, however, only partly attributable to the longer duration of sunshine because radiation is higher than would be expected from the longer duration of sunshine alone. A similar effect at Aberporth results from clean air, but despite the low level of pollution on the south coast, peak clear‐weather values are not abnormally high. Supplementation occurs on days that are not wholly clear; it is suggested that this is a result of reflection from orographic cloud. Copyright © 1968 Royal Meteorological Society"
"16533323300;16531829800;","Climate change over the Polar Ocean. I - The radiation budget",1967,"10.1007/BF02319107","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3743101769&doi=10.1007%2fBF02319107&partnerID=40&md5=8d97d6dcbc4ed8d461a228a1b19c4c1d","Climatic change results from changes in the terms of the energy equation. The present study consists of an analysis of possible changes in the radiative terms of the Polar Ocean energy budget. The absorbed global radiation at the surface depends mainly on clouds and surface albedo. These factors are discussed, and the absorbed global radiation is presented for various extreme surface and atmospheric conditions. The short wave radiation absorbed in the atmosphere is next discussed. It is apparent that variations in the atmospheric short wave absorption are of rather small importance for climatic change. There is greater possiblity of variations in long wave radiation than of solar radiation. theoretical polar atmospheres are discussed, with the consequent changes in the radiation balance. The conclusion appears that the atmosphere is at present adjusted in the best possible way for the conservation of energy. Long wave fluxes have been calculated for the condition of an open Polar Ocean in winter and for a Polar Ocean completely frozen throughout the year. It is concluded that, for cloudless conditions, there is little possibility for a change in the long wave balance in summer; the long wave balance would become much more negative in winter; the development of a winter balance less negative than the present seems unlikely. Changes in surface conditions are much more important than changes in the atmosphere, for the long wave radiation budget. Various radiation budgets are presented, for different assumed conditions. The optimum surface conditions would occur with winter overcast and summer cloudless sky. The annual radiation balances would become: {Mathematical expression} The earth-atmosphere radiation budget is presented for an open Polar Ocean with cloud conditions suchas presently found over the Norwegian Sea. It is apparent that the Polar Ocean is at present in a delicate radiational balance, and relatively minor variations in any term can result in a process leading to complete freeze-over or to complete melting. The atmospheric heat advection required with an open Polar Ocean would decrease significantly. In winter, it is even possible that this term in the energy budget might become negative (heat export from the Polar Ocean). © 1967 Springer-Verlag."
"22999817900;","The growth of cloud droplets by coalescence",1966,"10.1002/qj.49709239108","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978552472&doi=10.1002%2fqj.49709239108&partnerID=40&md5=cd36c66a5bfd4f0a1b8e4822ff3b35b8","A simple model of a cloud in which drops of different sizes are assumed to be falling at their terminal velocities is used to study the development of drops with radii up to 40 μ by the coalescence mechanism. It is not clear what initial distributions of drop sizes should be used in this study and therefore the development of larger drops from several different distributions which are thought to be characteristic of the early stages of various types of cumuli are compared. In this part of the paper Hocking's (1959) values of the collection efficiencies are assumed to apply. It is found that large drops develop rapidly in maritime clouds, and for clouds characteristic of continental climates it is shown that the maximum drop radius needs to be greater than about 22μ for the coalescence mechanism to be effective. There must also be an adequate supply of drops with radii between 14 and 20 μ. The effects of small increases in the collection efficiencies which may be caused by various factors, such as turbulence or electric fields, are studied with the model using two different initial drop size distributions. It is found that the most important single parameter in determining the onset of the coalescence mechanism is the minimum drop size capable of capturing still smaller drops. Generally, a significant effect is found if the change in the collection efficiency is equivalent to increasing the radii of the interacting drops by more than about 2μ. It is suggested that any future computations or experiments to determine changes in the collection efficiencies should look for effects of this magnitude. Copyright © 1966 Royal Meteorological Society"
"35132919800;35930219600;7801379691;","Part II an investigation on clothed men under indoor conditions",1959,"10.1007/BF02268739","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34347180684&doi=10.1007%2fBF02268739&partnerID=40&md5=f8ad09826d10794a32fe09294a18a841","Clothed men at rest were exposed to two conditioning ""indoor"" environments (""British"", coolmoist; ""American"", warm dry) for 45 minutes, and then to a cold environment (36°F) at moderate and high relative humidity (50% and 85%). The following measurements were taken: Temperature-skin, rectum and clothing gradients; nude body weight change and metabolism; subjective data. An attempt was made to measure clothing humidity gradients. The results showed that warm conditioning kept the clothing and skin at a higher temperature for a matter of 1 1/2 hours or more during cold exposure. The physiological value of such conditioning may be less marked under field conditions. No physiological objective or subjective differences of practical importance were found between the effects of still air at 36°F at moderate or high humidity, except for the finding of a slightly warmer skin of the chest at the high humidity. These results agree fairly well with those of other workers for nude men. From the date obtained there is no clear evidence that ""sorption"" heat of wool is an important factor in keeping the body warm at resting conditions. Under field conditions, ""sorption"" heat might be of still less value. There is no basis for the supposition that moist air is either a better thermal conductor or a more efficient heat convector than dry air. The physiological difference between ""dry cold"" and ""damp cold"" is not due to properties of humid air, but to the associated weather or climatic differences (solar radiation, cloud cover, wind, barometric pressure, etc.) and, to some extent, to the mode of living indoors. Data from physical models and from physiological experiments in climatic chambers cannot be directly transposed into the realities of weather and climate out of doors. © 1959 Swets & Zeitlinger B.V."
"57217321380;","Seasonal and other temperature changes in the Antarctic atmosphere",1959,"10.1002/qj.49708536503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979322022&doi=10.1002%2fqj.49708536503&partnerID=40&md5=637b45a5dac431e6e38e1b8b96d521bd","The annual variation of temperature in Antarctica has interesting properties: it is largest in the stratosphere (50° to 60°C), smaller at the surface (20° to 40°C) and smallest in the troposphere (10°C). During the winter night the troposphere temperature decreases only slightly while the stratosphere temperature drops steadily at about 1/4°C per day. This differential cooling, which weakens and at times wipes out the tropopause, is caused, on the one hand, by intense horizontal advection of maritime air into the Antarctic troposphere, and, on the other hand, by very little advection through the strong stratospheric jet stream encircling Antarctica. This ventilation of the Antarctic troposphere by warm marine air causes large portions of Antarctica to exhibit the kernlose winter‐temperature curve instead of the sharp winter minimum usually found in polar continental climate. Anomalously high June temperatures in the lower troposphere at Little America are attributed to intense cyclones which form in the Ross Sea area and advect air from the lightly ice‐clad or open ocean located not too far north of the Ross Sea. Large deviations in average monthly temperatures are found in the Ross Sea area which are undoubtedly a reflection of large year‐to‐year circulation changes in that area. The Antarctic and Arctic stratospheres exhibit quite different temperature behaviours after the winter solstice. The Antarctic stratosphere continues to cool until the sun returns and then warms as much as 50°C in 1 month. On the other hand, the Arctic stratosphere exhibits a warming of 30° to 40°C, sometimes beginning 6 weeks before the sun returns. A secular trend of temperature since 1912 of + 2·6°C at Little America (78° 12'S, 162° 15′W) compares with a + 6·2°C trend at Spitsbergen (78° 04′N, 13° 38′E). Finally, temperature and outgoing radiation observations made at the South Pole I.G.Y. Station during the cold period of 19‐24 April 1958 are presented to illustrate quantitatively the important effect of warm cloud radiation on surface air temperature and its vertical gradient. Copyright © 1959 Royal Meteorological Society"
"6701882465;","The O18-abundance in fresh water",1954,"10.1016/0016-7037(54)90003-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001253493&doi=10.1016%2f0016-7037%2854%2990003-4&partnerID=40&md5=ac7bafbc699e80e5b5068730b4a3ce3d","Fresh water of various origins as distinct from ocean water shows great variations in O18-abundance. Proceeding from the temperate towards the colder climates a considerable decrease is noticeable. It is demonstrated that the O18-abundance in atmospheric water vapour is dependent on (a) the precipitation temperature, (b) the origin of the vapour and (c) the average cooling of the vapour during the circulation of the water in nature, whereas the O18-abundance in a certain precipitation, further, depends on (d) the condensation temperature, (e) the cooling since the beginning of the condensation of the vapour in question and (f) the evaporation during the fall of the precipitation from cloud to ground. Furthermore, the O18-abundance in ground water from a certain locality depends on (g) the evaporation from the precipitation since its reaching the ground and (h) the possible exchange of O18 between the water and oxygenic substances in the ground. Computations on this basis and on measurements of the O18-abundance of ocean water are in agreement with measurements of fresh water of various origins. © 1954."
"23045461700;","The nature of convection as revealed by soaring birds and dragonflies",1954,"10.1002/qj.49708034308","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979326830&doi=10.1002%2fqj.49708034308&partnerID=40&md5=c0e2f391bc5a85084d54d1a8a3b93519","Birds and dragonflies can be used as indicators of the extent and intensity of vertical currents, particularly of the nature of convection below cloud base during its period of growth. The bubble theory of Scorer and Ludlam is used to interpret the observations of Hankin in India. The possibility of deriving information from the flight of swallows in Britain is also discussed. In hot sunshine and no wind the air appears to stream steadily upwards from fixed places for the first few metres. The birds indicate that convection develops upwards, the heavier ones which soar at greater heights taking to the air last. The upcurrents are stronger and wider at greater height and drift with the wind; they react more slowly at greater height to changes of sunshine on the ground. When convection is intense the upcurrents appear more sharp‐edged. Puffs of wind are associated with the descent of air from above the superadiabatic layer to replace a part of that layer that is ascending as a newly‐created bubble. When the air is stirred mechanically by wind, bubble formation in the lowest layers is reduced. It is suggested that air movements on the scale of ordinary convection are an element in the climate as important as any other in the life of many birds. Copyright © 1954 Royal Meteorological Society"
"7003708866;","Some recent climatic changes in Washington, D.C.",1951,"10.1007/BF02242591","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34347198684&doi=10.1007%2fBF02242591&partnerID=40&md5=8abdbbc7a919d65a4ab8e3ab8f099f33","The frequency of occurrence of clear and cloudy days in Washington, D. C., is compared for the intervals 1891-1920 and 1921-1950. There has been a steady increase of cloudy days, 36 more per year, and a decrease of clear days, 57 less per year. This change is reflected in all months of the year even though to a varying degree. The monthly frequency distributions show a statistically barely significant difference between the two intervals. This difference, in the light of collateral evidence, is, however, not attributable to chance. In conjunction with trends observed in temperature, dew point, and humidity values, only part of the change in cloud conditions can be ascribed to the growth of the city but is more likely due to the increasing maritime character of the climate in the northeastern United States. © 1951 Springer-Verlag."
"57190095281;","The modification of continental polar air over Hudson Bay",1951,"10.1002/qj.49707733304","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977296600&doi=10.1002%2fqj.49707733304&partnerID=40&md5=c1907ff886e61a7bcaeaa647ecdc16c2","Changes in the physical properties of continental polar air are studied for air currents with trajectories over the Hudson Bay region. Computations indicate that westerly air streams crossing Hudson Bay in early winter are modified to a depth of 5 to 10 thousand ft. By midwinter, however, the modification is found to be negligible. This lack of modification in midwinter is attributed to the formation of an ice surface on Hudson Bay. Changes in the climate of the surrounding area caused by the formation of ice on Hudson Bay are illustrated by changes in temperature, cloud and snowfall. The modifying influence of the Bay in cooling the air in summer and heating the air in early winter is also discussed. Copyright © 1951 Royal Meteorological Society"
"16672630300;24745161300;","Instrumentation for recording microclimatological factors",1951,"10.1029/TR032i006p00833","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981749912&doi=10.1029%2fTR032i006p00833&partnerID=40&md5=4ca6109cb6203866c3706b85fba5c164","The objectives, means, and some of the results of intensive studies of the thermal aspects of microclimatological environment are discussed. The proposed Table 1 of weather types is believed in general to combine rather effectively the European classification, depending on air mass, and the American description by cloud cover. The latter is the more specific for insolation, but the former is most significant for nocturnal heat rates, for moisture, and for air “quality.” The special instrumentation described has been developed in studies of heat transfer from animals and plants, particularly for measuring conduction and radiation. Such electric sensing elements seem to have use in the overall measurement of agricultural climatic environment. The recording potentiometers needed for the micro studies made possible the automatic recording of all the regular weather‐station observations described. It is hoped that discussion will lead to some general agreement on minimum instrumentation. Any such agreement would encourage the establishment of many more environment stations and constitute an important step from qualitative toward quantitative experiments. Examples of the usefulness of the instrumentation are described and a heat balance between solar and sky radiation and the ground is discussed. With adequate understanding of heat balance, we believe that agricultural research findings at one station can be extended to other areas of somewhat different climate. ©1951. American Geophysical Union. All Rights Reserved."
"57216248000;","Cloudburst on San Gabriel Peak, Los Angeles County, California",1927,"10.1130/GSAB-38-443","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84903154404&doi=10.1130%2fGSAB-38-443&partnerID=40&md5=79094f4dd41dd70e466683a243e45efc",[No abstract available]
"23084986900;","The influence of the atmospheric constituents upon climate",1927,"10.1029/TR008i001p00019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979189531&doi=10.1029%2fTR008i001p00019&partnerID=40&md5=e2421204d65ed0f62e4e29860199edf9","Climate is largely determined by the prevailing range of temperature. The temperature is maintained first, by the solar radiation which continuously fails upon our atmosphere at the mean rate of 1.93 calories per square centimeter per minute; and secondly, by the exceedingly complicated series of absorptions, scatterings, reflections, endless re‐radiations, and convection‐ and conduction‐effects which result from the passage of the solar beam through the atmosphere. Langley, and more recently Dietzius and others, have shown that the Moon, receiving solar radiation per unit area identical with the Earth, experiences within the brief interval of a lunar eclipse a change of temperature ranging from about that of boiling water to far below freezing. On the Earth the average daily range is less than 10° C and seldom exceeds 20° C. The difference is due to this: the Earth has an atmosphere; the Moon has not. Oxygen and nitrogen, which comprise the bulk of the atmosphere, have relatively little effect on temperature. From other constituents, however, comprising less than three per cent of the weight of the atmosphere are highly important as affecting temperatures. These constituents are water (both as water vapor and in the form of clouds), dust, ozone, and carbon‐dioxide. ©1927. American Geophysical Union. All Rights Reserved."