Author(s) ID,Title,Year,DOI,Link,Abstract
"7101835903;","New refinements and validation of the MODIS Land-Surface Temperature/Emissivity products",2008,"10.1016/j.rse.2006.06.026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36249010367&doi=10.1016%2fj.rse.2006.06.026&partnerID=40&md5=4f25ac2b41eec9c9dbcaf9d6b3264bb6","This paper discusses the lessons learned from analysis of the Moderate Resolution Imaging Spectroradiometer (MODIS) Land-Surface Temperature/Emissivity (LST) products in the current (V4) and previous versions, and presents eight new refinements for V5 product generation executive code (PGE16) and the test results with real Terra and Aqua MODIS data. The major refinements include considering surface elevation when using the MODIS cloudmask product, removal of temporal averaging in the 1 km daily level-3 LST product, removal of cloud-contaminated LSTs in level-3 LST products, and the refinements for the day/night LST algorithm. These refinements significantly improved the spatial coverage of LSTs, especially in highland regions, and the accuracy and stability of the MODIS LST products. Comparisons between V5 LSTs and in-situ values in 47 clear-sky cases (in the LST range from - 10 °C to 58 °C and atmospheric column water vapor range from 0.4 to 3.5 cm) indicate that the accuracy of the MODIS LST product is better than 1 K in most cases (39 out of 47) and the root of mean squares of differences is less than 0.7 K for all 47 cases or 0.5 K for all but the 8 cases apparently with heavy aerosol loadings. Emissivities retrieved by the day/night algorithm are well compared to the surface emissivity spectra measured by a sun-shadow method in two field campaigns. The time series of V5 MODIS LST product over two sites (Lake Tahoe in California and Namco lake in Tibet) in 2003 are evaluated, showing that the quantity and quality of MODIS LST products depend on clear-sky conditions because of the inherent limitation of the thermal infrared remote sensing. © 2007 Elsevier Inc. All rights reserved."
"7101835903;7601314333;56104541600;7409077047;","Validation of the land-surface temperature products retrieved from terra moderate resolution imaging spectroradiometer data",2002,"10.1016/S0034-4257(02)00093-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036846044&doi=10.1016%2fS0034-4257%2802%2900093-7&partnerID=40&md5=04f9a926abe0cb761d13b2b1b708a9c1","This paper presents the status of land-surface temperature (LST) standard products retrieved from Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) data. Based on estimates of the channel-dependence error and noise equivalent temperature difference (NEDT) and the calibration accuracy of MODIS thermal-infrared data, the impact of instrument performance on the accuracy of LST is discussed. A double-screen scheme based on the difference between the 5-km LST retrieved by the day/night LST algorithm and the aggregated 1-km LST retrieved by the generalized split-window algorithm, and the difference between daytime and nighttime LSTs, is proposed to remove the LSTs contaminated with cloud effects. The accuracy of daily MODIS LST product at 1-km resolution, which was produced by the generalized split-window algorithm, was validated in 11 clear-sky cases with in situ measurement data collected in field campaigns in 2000 and 2001. The MODIS LST accuracy is better than 1 K in the range from 263 to 300 K over Lake Titicaca in Bolivia, Mono Lake, Bridgeport grassland, and a rice field in Chico, CA, and Walker Lake, Nevada (NV), in the atmospheric column water vapor range from 0.4 to 3.0 cm. It is difficult to validate the daytime LST product over land sites rather than lakes with ground-based measurements alone because of the high spatial variations in the in situ LST measurement data, which was verified by the daytime data of the MODIS Airborne Simulator (MAS) over a grassland in Bridgeport, CA, on October 6, 2000. In six cases over a silt playa in Railroad Valley, NV, the 1-km MODIS LSTs are a few Kelvin degrees lower than the in situ measured LSTs because the surface emissivities inferred from land cover types in the split-window LST method are often overestimated in semi-arid and arid regions. After a correction with the difference between the 5-km LST retrieved by the day/night LST method and the LST aggregated from 1-km LSTs retrieved by the split-window method, the MODIS LSTs agree with in situ measured LSTs within ± 1 K in the range 263-322 K for the six cases in Railroad Valley and one case of snowcover in Bridgeport, CA, leading a recommendation for use of the 5-km LST product retrieved by the day/night LST method in bare and sparse vegetated areas. © 2002 Elsevier Science Inc. All rights reserved."
"6701689811;35577097300;","Radiative effects of natural aerosols: A review",2005,"10.1016/j.atmosenv.2004.12.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-16344382454&doi=10.1016%2fj.atmosenv.2004.12.029&partnerID=40&md5=ef781c3e5a1c690ebde61cf79ef297c9","In recent years, there has been a substantial increase in interest in the influence of anthropogenic aerosols on climate through both direct and indirect effects. Several extensive investigations and coordinated field campaigns have been carried out to assess the impact of anthropogenic aerosols on climate. However, there are far fewer studies on natural aerosols than on anthropogenic aerosols, despite their importance. Natural aerosols are particularly important because they provide a kind of base level to aerosol impact, and there is no effective control on them, unlike their anthropogenic counterparts. Besides, on a global scale the abundance of natural aerosols is several times greater than that of the major anthropogenic aerosols (sulphate, soot and organics). The major natural aerosol components are sea salt, soil dust, natural sulphates, volcanic aerosols, and those generated by natural forest fires. As with anthropogenic aerosols, the abundance of natural aerosols such as soil dust is also increasing, due to processes such as deforestation, which exposes more land areas which may then interact directly with the atmosphere, and due to other human activities. Since a major fraction of the natural aerosol (sea salt and natural sulphate) is of the non-absorbing type (and hygroscopic), it partly offsets the warming due to greenhouse gases as well as that due to absorbing aerosols (e.g., soot). The mineral dust transported over land and ocean causes surface cooling (due to scattering and absorption) simultaneously with lower atmospheric heating (due to absorption); this could in turn intensify a low-level inversion and increase atmospheric stability and reduce convection. To accurately predict the impact of dust aerosols on climate, the spatial and temporal distribution of dust is essential. The regional characteristics of dust source function are poorly understood due to the lack of an adequate database. The reduction of solar radiation at the surface would lead to a reduction in the sensible heat flux and all these will lead to perturbations in the regional and global climate. Enhanced concentration of sea salt aerosols at high wind speed would lead to more condensation nuclei, increase in the cloud droplet concentration and hence cloud albedo. Even though direct radiative impacts due to sea salt and natural sulphate are small compared to those due to anthropogenic counterparts, their indirect effects (and the uncertainties) are much larger. There is a considerable uncertainty in sea salt aerosol radiative forcing due to an inadequate database over oceans. The presence of natural aerosols may influence the radiative impact of anthropogenic aerosols, and it is difficult to separate the natural and anthropogenic aerosol contributions to radiative forcing when they are in a mixed state. Hence it is necessary to document the radiative effects of natural aerosols, especially in the tropics where the natural sources are strong. This is the subject matter of this review. © 2005 Elsevier Ltd. All rights reserved."
"57203180094;55537009700;7102665424;6603582402;7006159471;7201386359;57193332948;7403644649;7103313899;55106623200;","Continuous observations of Asian dust and other aerosols by polarization lidars in China and Japan during ACE-Asia",2004,"10.1029/2002JD003253","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142571317&doi=10.1029%2f2002JD003253&partnerID=40&md5=7e1b3a693934ff966d71bfce78f444e0","Continuous observations of aerosols in China and Japan were made by polarization lidars during March to May 2001, corresponding with the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) field campaign period. Lidars in Beijing, Nagasaki, and Tsukuba were continuously operated regardless of weather conditions. Scatterers in the atmosphere were categorized for all vertical profiles, and occurrence frequencies of dust, spherical aerosols, and clouds up to 6 km were calculated. The frequency of dust was highest in Beijing for the whole height range. There was a peak of dust occurrence near the ground in Nagasaki. Dust was frequently detected in the free troposphere in Tsukuba. The contributions of dust and spherical aerosols to the total backscattering coefficient were estimated from the depolarization ratio with the assumption of the external mixture of both kinds of aerosols. Vertical profiles of backscattering by dust and by spherical aerosols represented the different characteristics of these aerosols. The monthly averaged backscattering coefficients by dust near the surface were 0.003/km/sr in Beijing, 0.001-0.002/km/sr in Nagasaki, and 0.0006/km/sr in Tsukuba. The backscattering coefficients by spherical aerosols near the surface were 0.002-0.004/km/sr at all three observatories. We compared the derived backscattering coefficients with aerosol mass concentrations calculated by a numerical model, Chemical Weather Forecasting System (CFORS). CFORS reproduced well the vertical structures of the tall dust events and the enhancements of spherical aerosols throughout the observation period. A specific dust event on 16-19 May 2001 was analyzed by using five lidars in Japan, and its fine structure is described. Copyright 2OO4 by the American Geophysical Union."
"6505932008;6507731482;25953950400;7004715270;6603385031;","Impacts of nucleating aerosol on Florida storms. Part I: Mesoscale simulations",2006,"10.1175/JAS3713.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746932441&doi=10.1175%2fJAS3713.1&partnerID=40&md5=0c54bec73c402d46e83a6645b9fefd72","Toward the end of the Cirrus Regional Study of Tropical Anvils and Cirrus Layer-Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign held during July 2002, high concentrations of Saharan dust, which can serve as cloud condensation nuclei (CCN), giant CCN (GCCN), and ice-forming nuclei (IFN) were observed over the peninsula of Florida. To investigate the impacts of enhanced aerosol concentrations on the characteristics of convective storms and their subsequent anvil development, sensitivity tests are conducted using the Regional Atmospheric Modeling System (RAMS) model, in which the initialization profiles of CCN, GCCN, and IFN concentrations are varied. These variations are found to have significant effects on the storm dynamics and microphysical processes, as well as on the surface precipitation. Updrafts are consistently stronger as the aerosol concentrations are increased. The anvils cover a smaller area but are better organized and have larger condensate mixing ratio maxima in the cases with greater aerosol concentrations. Cloud water mass tends to increase with increasing aerosol concentrations, with enhanced GCCN concentrations having the most significant influence. Increasing either the GCCN or IFN concentrations produces the most rainfall at the surface whereas enhanced CCN concentrations reduce surface rainfall. Higher IFN concentrations produce ice at warmer temperatures and deeper anvils, but simultaneously increasing the concentrations of CCN and GCCN leads to more supercooled liquid water available for freezing and greater ice mixing ratios. Graupel mixing ratios decrease and hail mixing ratios increase with increasing aerosol concentrations. Higher concentrations of GCCN and IFN result in greater accumulated surface precipitation initially. By the end of the simulation period, however, the accumulated precipitation is the greatest for the case in which the aerosol concentrations are lowest. Such changes in the dynamical and microphysical characteristics of convective storms as a result of the variations in aerosol concentrations have potential climate consequences, both through cloud radiative effects and the hydrological cycle. The impacts of varying CCN, GCCN, and IFN concentrations on the anvils will be discussed more fully in Part II. © 2006 American Meteorological Society."
"7004003763;7201504886;7202762223;7202381052;35473805400;23491331000;22975069200;7404521962;7801634218;6602765265;7004084412;57202521210;9535817700;7006901405;23491463000;55896920900;7005886535;55454856700;7004885872;25953950400;6602111828;6701590980;7202185413;22953316500;7103337730;35393120300;7402565763;6603431534;55663817800;7103119050;23019327900;23492864500;57203054678;14020513000;7402049334;6603566335;12645126500;7003406689;57209341911;7202408732;7004198777;7005035762;","Rain in shallow cumulus over the ocean: The RICO campaign",2007,"10.1175/BAMS-88-12-1912","https://www.scopus.com/inward/record.uri?eid=2-s2.0-38949157156&doi=10.1175%2fBAMS-88-12-1912&partnerID=40&md5=33943f54e6cff57e91da132737d69a0f","Shallow, maritime cumuli are ubiquitous over much of the tropical oceans, and characterizing their properties is important to understanding weather and climate. The Rain in Cumulus over the Ocean (RICO) field campaign, which took place during November 2004-January 2005 in the trades over the western Atlantic, emphasized measurements of processes related to the formation of rain in shallow cumuli, and how rain subsequently modifies the structure and ensemble statistics of trade wind clouds. Eight weeks of nearly continuous S-band polarimetric radar sampling, 57 flights from three heavily instrumented research aircraft, and a suite of ground- and ship-based instrumentation provided data on trade wind clouds with unprecedented resolution. Observational strategies employed during RICO capitalized on the advances in remote sensing and other instrumentation to provide insight into processes that span a range of scales and that lie at the heart of questions relating to the cause and effects of rain from shallow maritime cumuli. © 2008 American Meteorological Society Privacy Policy and Disclaimer."
"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."
"7201826462;7005729142;7403931916;12141789600;","Bulk scattering properties for the remote sensing of ice clouds. Part I: Microphysical data and models",2005,"10.1175/JAM2308.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-24944572068&doi=10.1175%2fJAM2308.1&partnerID=40&md5=0021a5f35965f75a479d40f7f5c85e65","This study reports on the use of in situ data obtained in midlatitude and tropical ice clouds from airborne sampling probes and balloon-borne replicators as the basis for the development of bulk scattering models for use in satellite remote sensing applications. Airborne sampling instrumentation includes the two-dimensional cloud (2D-C), two-dimensional precipitation (2D-P), high-volume precipitation spectrometer (HVPS), cloud particle imager (CPI), and NCAR video ice particle sampler (VIPS) probes. Herein the development of a comprehensive set of microphysical models based on in situ measurements of particle size distributions (PSDs) is discussed. Two parameters are developed and examined: ice water content (IWC) and median mass diameter Dm. Comparisons are provided between the IWC and Dm values derived from in situ measurements obtained during a series of field campaigns held in the midlatitude and tropical regions and those calculated from a set of modeled ice particles used for light-scattering calculations. The ice particle types considered in this study include droxtals, hexagonal plates, solid columns, hollow columns, aggregates, and 3D bullet rosettes. It is shown that no single habit accurately replicates the derived IWC and Dm values, but a mixture of habits can significantly improve the comparison of these bulk microphysical properties. In addition, the relationship between Dm and the effective particle size Deff, defined as 1.5 times the ratio of ice particle volume to projected area for a given PSD, is investigated. Based on these results, a subset of microphysical models is chosen as the basis for the development of ice cloud bulk scattering models in Part II of this study. © 2005 American Meteorological Society."
"57192158842;6602599215;7103024611;7202305982;","The structural and radiative consistency of three-dimensional tree reconstructions from terrestrial lidar",2009,"10.1016/j.rse.2009.01.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-63649103808&doi=10.1016%2fj.rse.2009.01.017&partnerID=40&md5=376fd549faf6b83b5bd090841980413c","A novel methodology is proposed to reconstruct 3D tree architectures from terrestrial LiDAR (TLiDAR) scans. The methodology is robust and relatively insensitive to wind- and occlusion-induced artefacts in the 3D TLiDAR point clouds. A quantitative evaluation of structural attributes, like the vertical foliage and wood area profiles, as well as the shoot orientation distribution, was performed. Due to the difficulties of acquiring reliable and accurate estimates of these parameters in the field, an original evaluation approach was chosen that reproduces the TLiDAR scanning and subsequent tree reconstruction process in a virtual environment. In a second step the reconstructed tree models were ingested in a validated 3D radiative transfer model to simulate both their reflectance signatures (observable by space borne instruments) and directional transmission properties (measurable during field campaigns) under various spectral, illumination and tree density scenarios. The results of these evaluations confirm the appropriateness of the proposed tree reconstruction model for the generation of structurally and radiatively faithful copies of existing plant and canopy architectures. © 2009 Elsevier Inc. All rights reserved."
"56220041200;8789145400;23995015000;6601988043;35548797900;8789145800;","Nitrated phenols in the atmosphere: A review",2005,"10.1016/j.atmosenv.2004.09.044","https://www.scopus.com/inward/record.uri?eid=2-s2.0-10344227168&doi=10.1016%2fj.atmosenv.2004.09.044&partnerID=40&md5=2da8e8598ce3befb95fa61a954ec4b96","This paper reviews the data concerning the atmospheric occurrence of nitrophenols, both in the gas and in the condensed phase (rainwater, cloud, fog and snow). Data obtained from field campaigns are reported, together with a description of the analytical techniques employed for the identification and quantification of nitrophenols. Analysis is usually performed using techniques such as High Performance Liquid Chromatography (HPLC) or Gas Chromatography-Mass Spectrometry (GC-MS), with the sampling method largely determined according to the matrix under investigation. The sources of atmospheric nitrophenols include direct emissions resulting from combustion processes, hydrolysis of pesticides (e.g. parathion) and the secondary formation of nitrophenols in the atmosphere. Atmospheric nitration of phenol can take place both in the gas and liquid phases, but the relative importance of these processes is still under discussion. The gas-phase nitration involves reaction between phenol and .OH+.NO2 during the day or .NO 3+.NO2 during the night. Gas-phase nitration during the day yields only 2-nitrophenol (2-NP); while during the night it is thought that both 2-NP and 4-nitrophenol (4-NP) may be formed. Because of many gaps in the experimental evidence it is apparent that more research is required to indicate whether the 4-NP present in the environment can be accounted for by this nighttime process. Nitration in the condensed phase can be initiated by electrophilic nitration agents such as N2O5 and ClNO 2. Other liquid-phase processes can also take place, in the presence of .NO3, nitrate and nitrite, in the dark and under irradiation. Condensed-phase processes have been shown to yield 2- and 4-NP in similar amounts. It is also important to consider the atmospheric sinks of nitrophenols. The rate constant for the reaction between 2-NP and .OH in the gas phase is rather low (9.0×10-13 cm3 molecule-1 s-1), while incomplete data are available for the reaction with .NO3. In addition, condensed-phase processes might also represent an important nitrophenol sink. Potential loss routes include the reaction with radicals such as .OH and .NO3 in aqueous solution as well as the nitration to form the dinitrophenols. © 2004 Elsevier Ltd. All rights reserved."
"7402115506;6701858531;6603369413;6701718885;7404350742;7003448155;7102965584;23013553000;7006161438;6701738681;6603185401;","The GOES-R Geostationary Lightning Mapper (GLM)",2013,"10.1016/j.atmosres.2013.01.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874556714&doi=10.1016%2fj.atmosres.2013.01.006&partnerID=40&md5=fcadc03c00145e3b42ea2a54fba12fc4","The Geostationary Operational Environmental Satellite R-series (GOES-R) is the next block of four satellites to follow the existing GOES constellation currently operating over the Western Hemisphere. Advanced spacecraft and instrument technology will support expanded detection of environmental phenomena, resulting in more timely and accurate forecasts and warnings. Advancements over current GOES capabilities include a new capability for total lightning detection (cloud and cloud-to-ground flashes) from the Geostationary Lightning Mapper (GLM), and improved cloud and moisture imagery with the 16-channel Advanced Baseline Imager (ABI). The GLM will map total lightning activity continuously day and night with near-uniform storm-scale spatial resolution of 8. km with a product refresh rate of less than 20. s over the Americas and adjacent oceanic regions in the western hemisphere. This will aid in forecasting severe storms and tornado activity, and convective weather impacts on aviation safety and efficiency. In parallel with the instrument development, an Algorithm Working Group (AWG) Lightning Detection Science and Applications Team developed the Level 2 (stroke and flash) algorithms from the Level 1 lightning event (pixel level) data. Proxy data sets used to develop the GLM operational algorithms as well as cal/val performance monitoring tools were derived from the NASA Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) instruments in low Earth orbit, and from ground-based lightning networks and intensive prelaunch field campaigns. The GLM will produce the same or similar lightning flash attributes provided by the LIS and OTD, and thus extend their combined climatology over the western hemisphere into the coming decades. Science and application development along with preoperational product demonstrations and evaluations at NWS forecast offices and NOAA testbeds will prepare the forecasters to use GLM as soon as possible after the planned launch and checkout of GOES-R in late 2015. New applications will use GLM alone, in combination with the ABI, or integrated (fused) with other available tools (weather radar and ground strike networks, nowcasting systems, mesoscale analysis, and numerical weather prediction models) in the hands of the forecaster responsible for issuing more timely and accurate forecasts and warnings. © 2013."
"10144282600;6603785227;7003921969;7005728241;57201177267;35461763400;7003741536;7402389200;56616299500;57212048688;","Including the sub-grid scale plume rise of vegetation fires in low resolution atmospheric transport models",2007,"10.5194/acp-7-3385-2007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547462179&doi=10.5194%2facp-7-3385-2007&partnerID=40&md5=2a638f670b35c1b9c6c847b1e1169685","We describe and begin to evaluate a parameterization to include the vertical transport of hot gases and particles emitted from biomass burning in low resolution atmospheric-chemistry transport models. This sub-grid transport mechanism is simulated by embedding a 1-D cloud-resolving model with appropriate lower boundary conditions in each column of the 3-D host model. Through assimilation of remote sensing fire products, we recognize which columns have fires. Using a land use dataset appropriate fire properties are selected. The host model provides the environmental conditions, allowing the plume rise to be simulated explicitly. The derived height of the plume is then used in the source emission field of the host model to determine the effective injection height, releasing the material emitted during the flaming phase at this height. Model results are compared with CO aircraft profiles from an Amazon basin field campaign and with satellite data, showing the huge impact that this mechanism has on model performance. We also show the relative role of each main vertical transport mechanisms, shallow and deep moist convection and the pyro-convection (dry or moist) induced by vegetation fires, on the distribution of biomass burning CO emissions in the troposphere."
"6701762451;7404062492;57192107995;7202586843;","Single particle measurements of the chemical composition of cirrus ice residue during CRYSTAL-FACE",2004,"10.1029/2003jd004032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442662188&doi=10.1029%2f2003jd004032&partnerID=40&md5=a16ff533fd82e325951973f45b0addc0","The first real-time, in situ, investigation of the chemical composition of the residue of cirrus ice crystals was performed during July 2002. This study was undertaken on a NASA WB-57F high-altitude research aircraft as part of CRYSTAL-FACE, a field campaign which sought to further our understanding of the relation of clouds, water vapor, and climate by characterizing, among other parameters, anvil cirrus formed about the Florida peninsula. A counter flow virtual impactor (CVI) was used to separate cirrus ice from the unactivated interstitial aerosol particles and evaporate condensed-phase water. Residual material, on a crystal-by-crystal basis, was subsequently analyzed using the NOAA Aeronomy Laboratory's Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Sampling was performed from 5 to 15 km altitude and from 12° to 28° north latitude within cirrus originating over land and ocean. Chemical composition measurements provided several important results. Sea salt was often incorporated into cirrus, consistent with homogeneous ice formation by aerosol particles from the marine boundary layer. Size measurements showed that large particles preferentially froze over smaller ones. Meteoritic material was found within ice crystals, indicative of a relation between stratospheric aerosol particles and tropospheric clouds. Mineral dust was the dominant residue observed in clouds formed during a dust transport event from the Sahara, consistent with a heterogeneous freezing mechanism. These results show that chemical composition and size are important determinants of which aerosol particles form cirrus ice crystals. Copyright 2004 by the American Geophysical Union."
"37099552800;53876886100;16233350800;46461233500;24537168200;23479194900;26027431900;10739566100;6506258154;15080710300;6602496366;17433787100;57214957748;14035386400;14420077300;24311471900;57203776263;11339750700;16833315000;34868441100;35461255500;7006712143;25522357400;36647693000;7003545995;7006708207;8657171200;56472932500;8871497700;9432343100;9235257000;8084443000;7005287667;6603135449;7006593624;7005069415;7006387246;","Organic aerosol components derived from 25 AMS data sets across Europe using a consistent ME-2 based source apportionment approach",2014,"10.5194/acp-14-6159-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84903207744&doi=10.5194%2facp-14-6159-2014&partnerID=40&md5=aa9687f555bd00f6640edf1d6dc4b582","Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) and the intensive campaigns of European Monitoring and Evaluation Programme (EMEP) during 2008 (May-June and September-October) and 2009 (February-March). In this paper we focus on the identification of the main organic aerosol sources and we define a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 data sets accounting for two urban, several rural and remote and two high altitude sites; therefore it is likely suitable for the treatment of AMS-related ambient data sets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Generally, our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling purposes. © Author(s) 2014."
"55207753100;55545335600;35369409100;56212802600;55533655900;","Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: Implication of regional secondary formation",2010,"10.5194/acp-10-947-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-75949091905&doi=10.5194%2facp-10-947-2010&partnerID=40&md5=34a7fb0a32c0b842deae938d6961addb","To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM 1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%-60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH 4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM10 and 87% of the PM1.8 in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing."
"7403213622;6602844623;6602367838;6701518904;23019327900;6507158373;","An objective method for deriving atmospheric structure from airborne lidar observations",2000,"10.1175/1520-0426(2000)017<1455:AOMFDA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034490928&doi=10.1175%2f1520-0426%282000%29017%3c1455%3aAOMFDA%3e2.0.CO%3b2&partnerID=40&md5=384179ab9886ceabf2625c3974516bae","Wavelet analysis is applied to airborne infrared lidar data to obtain an objective determination of boundaries in aerosol backscatter that are associated with boundary layer structure. This technique allows high-resolution spatial variability of planetary boundary layer height and other structures to be derived in complex, multilayered atmospheres. The technique is illustrated using data from four different lidar systems deployed on four different field campaigns. One case illustrates high-frequency retrieval of the top of a strongly convective boundary layer. A second case illustrates the retrieval of multiple layers in a complex, stably stratified region of the lower troposphere. The method is easily modified to allow for varying aerosol distributions and data quality. Two more difficult cases, data that contain a great deal for instrumental noise and a cloud-topped convective layer, are described briefly. The method is also adaptable to model analysis, as is shown via application to large eddy simulation data."
"6602999057;7202803069;","Mineral dust aerosols over the Sahara: Meteorological controls on emission and transport and implications for modeling",2012,"10.1029/2011RG000362","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856947014&doi=10.1029%2f2011RG000362&partnerID=40&md5=e769a1c09105ca07949fafc0445c2eae","Atmospheric mineral dust has recently become an important research field in Earth system science because of its impacts on radiation, clouds, atmospheric dynamics and chemistry, air quality, and biogeochemical cycles. Studying and modeling dust emission and transport over the world's largest source region, the Sahara, is particularly challenging because of the complex meteorology and a very sparse observational network. Recent advances in satellite retrievals together with ground-and aircraft-based field campaigns have fostered our understanding of the spatiotemporal variability of the dust aerosol and its atmospheric drivers. We now have a more complete picture of the key processes in the atmosphere associated with dust emission. These cover a range of scales from (1) synoptic scale cyclones in the northern sector of the Sahara, harmattan surges and African easterly waves, through (2) low-level jets and cold pools of mesoscale convective systems (particularly over the Sahel), to (3) microscale dust devils and dusty plumes, each with its own pronounced diurnal and seasonal characteristics. This paper summarizes recent progress on monitoring and analyzing the dust distribution over the Sahara and discusses implications for numerical modeling. Among the key challenges for the future are a better quantification of the relative importance of single processes and a more realistic representation of the effects of the smaller-scale meteorological features in dust models. In particular, moist convection has been recognized as a major limitation to our understanding because of the inability of satellites to observe dust under clouds and the difficulties of numerical models to capture convective organization. Copyright 2012 by the American Geophysical Union."
"7006708207;55950593000;7103021308;56264677300;35461255500;35449990500;57205954997;7102496779;7006960661;7005486920;55945626100;7202923871;8779434700;7003984086;7102357095;","A dedicated study of New Particle Formation and Fate in the Coastal Environment (PARFORCE): Overview of objectives and achievements",2002,"10.1029/2001JD000555","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749991984&doi=10.1029%2f2001JD000555&partnerID=40&md5=ca89ae0c91dcf327205adf632b105023","A dedicated study into the formation of new particles, New Particle Formation and Fate in the Coastal Environment (PARFORCE), was conducted over a period from 1998 to 1999 at the Mace Head Atmospheric Research Station on the western coast of Ireland. Continuous measurements of new particle formation were taken over the 2-year period while two intensive field campaigns were also conducted, one in September 1998 and the other in June 1999. New particle events were observed on ∼90% of days and occurred throughout the year and in all air mass types. These events lasted for, typically, a few hours, with some events lasting more than 8 hours, and occurred during daylight hours coinciding with the occurrence of low tide and exposed shorelines. During these events, peak aerosol concentrations often exceeded 106 cm-3 under clean air conditions, while measured formation rates of detectable particle sizes (i.e., d &gt; 3 nm) were of the order of 104-105 cm-3 s-1. Nucleation rates of new particles were estimated to be, at least, of the order of 105-106 cm-3 s-1 and occurred for sulphuric acid concentrations above 2 × 106 molecules cm-3; however, no correlation existed between peak sulphuric acid concentrations, low tide occurrence, or nucleation events. Ternary nucleation theory of the H2SO4-H 2O-NH3 system predicts that nucleation rates far in excess of 106 cm-3 s-1 can readily occur for the given sulphuric acid concentrations; however, aerosol growth modeling studies predict that there is insufficient sulphuric acid to grow new particles (of ∼1 nm in size) into detectable sizes of 3 nm. Hygroscopic growth factor analysis of recently formed 8-nm particles illustrate that these particles must comprise some species significantly less soluble than sulphate aerosol. The nucleation-mode hygroscopic data, combined with the lack of detectable VOC emissions from coastal biota, the strong emission of biogenic halocarbon species, and the fingerprinting of iodine in recently formed (7 nm) particles suggest that the most likely species resulting in the growth of new particles to detectable sizes is an iodine oxide as suggested by previous laboratory experiments. It remains an open question whether nucleation is driven by self nucleation of iodine species, a halocarbon derivative, or whether first, stable clusters are formed through ternary nucleation of sulphuric acid, ammonia, and water vapor, followed by condensation growth into detectable sizes by condensation of iodine species. Airborne measurements confirm that nucleation occurs all along the coastline and that the coastal biogenic aerosol plume can extend many hundreds of kilometers away from the source. During the evolution of the coastal plume, particle growth is observed up to radiatively active sizes of 100 nm. Modeling studies of the yield of cloud-condensation nuclei suggest that the cloud condensation nuclei population can increase by ∼100%. Given that the production of new particles from coastal biogenic sources occurs at least all along the western coast of Europe, and possibly many other coastlines, it is suggested that coastal aerosols contribute significantly to the natural background aerosol population. Copyright 2002 by the American Geophysical Union."
"7005729142;7404040759;6506385754;6601988721;6602185473;7005598760;7004198777;6602550636;","A general approach for deriving the properties of cirrus and stratiform ice cloud particles",2002,"10.1175/1520-0469(2002)059<0003:AGAFDT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036329746&doi=10.1175%2f1520-0469%282002%29059%3c0003%3aAGAFDT%3e2.0.CO%3b2&partnerID=40&md5=b6ad03c33d2ddde1155e94e810e80a5c","A new approach is described for calculating the mass (m) and terminal velocity (Vt) of ice particles from airborne and balloon-borne imaging probe data as well as its applications for remote sensing and modeling studies. Unlike past studies that derived these parameters from the maximum (projected) dimension (D) and habit alone, the ""two-parameter approach"" uses D and the particle's projected cross-sectional area (A). Expressions were developed that relate the area ratio (Ar; the projected area of an ice particle normalized by the area of a circle with diameter D) to its effective density (pe) and to Vt. Habit-dependent, power-law relationships between pe and Ar were developed using analytic representations of the geometry of various types of planar and spatial ice crystals. Relationships were also derived from new or reanalyzed data for single ice particles and aggregates observed in clouds and at the ground. The mass relationships were evaluated by comparing calculations to direct measurements of ice water content (IWC). The calculations were from Particle Measuring Systems (PMS) 2D-C and 2D-P probes of particle size distributions in ice cloud layers on 3 days during an Atmospheric Measurement (ARM) field campaign in Oklahoma; the direct measurements were from counterflow virtual impactor (CVI) observations in ice cloud layers during the field campaign. Agreement was generally to within 20%, whereas using previous mass-dimension relationship approaches usually produced larger differences. Comparison of ground-based measurements of radar reflectivity with calculations from collocated balloon-borne ice crystal measurements also showed that the new method accurately captured the vertical reflectivity structure. Improvements in the accuracy of the estimates from the earlier mass-dimension relationships were achieved by converting them to the new form. A new, more accurate mass- dimension relationship for spatial, cirrus-type crystals was deduced deduced from the comparison. The relationship between Vt and Ar was derived from a combination of theory and observations. A new expression accounting for the drag coefficients of large aggregates was developed from observational data. Explicit relationships for calculating Vt as a function of D for aggregates with a variety of component crystals were developed."
"21734501300;7006185793;6601984485;7003385765;","National Lightning Detection Network (NLDN) performance in southern Arizona, Texas, and Oklahoma in 2003-2004",2007,"10.1029/2006JD007341","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547538591&doi=10.1029%2f2006JD007341&partnerID=40&md5=3f0955177e636c531d8b3c7869be64af","Four field campaigns were conducted in southern Arizona (AZ) and in northern Texas and southern Oklahoma (TX-OK) in 2003 and 2004 to evaluate the performance of the U.S. National Lightning Detection Network™ (NLDN) in detecting cloud-to-ground (CG) lightning after an upgrade in 2002 and 2003. The 2-year average flash detection efficiency (DE) in A-Z was 93% (1024/1097), and the measured (first plus subsequent) stroke DE was 76% (2746/3620). The corresponding values in TX-OK were 92% (338/367) and 86% (755/882), respectively. After correcting for the time resolution of the video camera (16.7 ms), we estimate that the actual NLDN stroke DE and video multiplicities were about 68% and 3.71 in AZ and 77% and 2.80 in TX-OK. The average DE for negative first strokes (92%) was larger than the measured DE for subsequent strokes that produced a new ground contact (81%) and the DE for subsequent strokes that remained in a preexisting channel (67%). The primary cause of the NLDN missing strokes was that the peak of the radiated electromagnetic field was below the NLDN detection threshold. The average estimated peak current (I<inf>p</inf>) of negative first strokes and,the average multiplicity of negative flashes varied from storm to storm and between the two regions, but this variability did not affect the DE as long as the recording sessions had more than 60 flashes. By analyzing the NLDN locations of subsequent strokes that remained in the same channel as the first stroke we infer that the median random position error of the NLDN was 424 m in AZ and 282 m in TX-OK. An evaluation of the classification of lightning type by the NLDN (i.e., CG stroke versus cloud pulse) showed that 1.4-7% (6/420 to 6/86) of the positive NLDN reports with an I<inf>p</inf> ≤ 10 kA in TX-OK were produced by CG strokes; 4.7-26% (5/106 to 5/19) of the positive reports with 10 kA ≤ I<inf>p</inf> ≤ 20 kA were CGs; and 67-95% (30/45 to 30/32) of the reports with I<inf>p</inf> ≥ +20 kA were CG strokes. Some 50-87% (52/104 to 52/60) of the negative, single-stroke NLDN reports in AZ and TX-OK with I<inf>p</inf> ≤ 10 kA were produced by CG flashes. Both the upper and lower bounds in these classification studies have observational biases. Copyright 2007 by the American Geophysical Union."
"7006434689;7006497723;7005069415;","Seasonal and diurnal variation of aerosol size distributions (10 < D < 750 nm) at a high-alpine site (Jungfraujoch 3580 m asl)",1999,"10.1029/1999JD900170","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033589491&doi=10.1029%2f1999JD900170&partnerID=40&md5=4fa3ced25edbda27b770c5815b78719e","During an extended field campaign at a high-alpine site (Jungfraujoch; 3580 m asl, Switzerland) from March 1997 to May 1998, the particle number size distribution (diameter D = 18-750 nm) and number concentration N (D &gt; 10 nm) were measured on a continuous basis. The number size distribution was dominated by particles with D &lt; 100 nm, while most of the surface area was in the accumulation mode size range (0.1-1 μm). Average size distributions exhibited a distinct bimodal shape which is generated and maintained by cloud processes and is less distinct in the free troposphere. Fitted modal diameters and standard deviations σ of the Aitken (20-100 nm) and accumulation modes were surprisingly constant throughout the year (DAit = 43 ± 3 nm; DAcc = 140 ± 6 nm; σAit = 2.13 ± 0.11; σAcc = 1.61 ± 0.03). The relative number concentrations in both modes are responsible for the seasonality observed in the shape of the size distribution. The high seasonality of NAcc with summer and winter values of ∼260 and ∼40 cm-3, respectively, is mainly due to transport of planetary boundary layer air to the station. In contrast, new particle formation is responsible for the high concentrations of nucleation mode particles (D &lt; 20 nm) which exhibited a maximum during the winter months. The relatively low seasonality found for NAit (summer, winter values: ∼530, ∼310 cm-3) is due to gas-to-particle conversion as well as transport processes. An analysis showed that a significant fraction of nucleation mode particles were formed by photochemical reactions. Copyright 1999 by the American Geophysical Union."
"6701806265;22633429500;7003696133;56087850300;6508333712;7101867299;7101600670;6701697023;35114533000;15047430100;7402655099;14044750400;7006728825;35745803100;8263830700;6603868770;8618154900;7004881313;6508080697;24376225300;35195710600;8927405700;35551238800;6603755619;11939841300;12766326800;6602497877;57204308821;7006450978;7004022660;7003510880;6701518904;56596460400;8555699700;37026305200;7402480218;14066601400;6701732679;6701593852;55339822300;7401522856;8565596200;7005030035;7003422540;7003972559;24559136600;55435417200;6603623135;15069732800;7402934750;6602177985;7101896538;7003875373;6701469150;7003968166;35326039600;7201423091;","The Convective and Orographically-induced Precipitation Study (COPS): The scientific strategy, the field phase, and research highlights",2011,"10.1002/qj.752","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79951883834&doi=10.1002%2fqj.752&partnerID=40&md5=747326a43ae30a05226640c68d0bedfa","Within the framework of the international field campaign COPS (Convective and Orographically-induced Precipitation Study), a large suite of state-of-the-art meteorological instrumentation was operated, partially combined for the first time. This includes networks of in situ and remote-sensing systems such as the Global Positioning System as well as a synergy of multi-wavelength passive and active remote-sensing instruments such as advanced radar and lidar systems. The COPS field phase was performed from 01 June to 31 August 2007 in a low-mountain area in southwestern Germany/eastern France covering the Vosges mountains, the Rhine valley and the Black Forest mountains. The collected data set covers the entire evolution of convective precipitation events in complex terrain from their initiation, to their development and mature phase until their decay. Eighteen Intensive Observation Periods with 37 operation days and eight additional Special Observation Periods were performed, providing a comprehensive data set covering different forcing conditions. In this article, an overview of the COPS scientific strategy, the field phase, and its first accomplishments is given. Highlights of the campaign are illustrated with several measurement examples. It is demonstrated that COPS research provides new insight into key processes leading to convection initiation and to the modification of precipitation by orography, in the improvement of quantitative precipitation forecasting by the assimilation of new observations, and in the performance of ensembles of convection-permitting models in complex terrain. © 2010 Royal Meteorological Society."
"16032925200;35228780900;6603174102;7006195421;14024872700;7202429440;7201432984;7005254328;7006399419;6602085876;35601748800;24537168200;11440963500;7003605315;7101959920;7403996091;","Particulate emissions from commercial shipping: Chemical, physical, and optical properties",2009,"10.1029/2008JD011300","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649991417&doi=10.1029%2f2008JD011300&partnerID=40&md5=402f0c64831204bc3cd393e430f370c5","We characterize particulate emissions on the basis of chemical, physical, and optical properties from commercial vessels. Observations during the Texas Air Quality Study/ Gulf of Mexico Atmospheric Composition and Climate Study 2006 field campaign provide chemical and physical characteristics including sulfate (SO2<inf>4</inf>-) mass, organic matter (OM) mass, black carbon (BC) mass, particulate matter (PM) mass, number concentrations (condensation nuclei (CN) > 5 nm), and cloud condensation nuclei (CCN). Optical characterization included multiple wavelength visible light absorption and extinction, extinction relative humidity dependence, and single scatter albedo (SSA). The global contribution of shipping PM was calculated to be 0.90 Tg a-1, in good agreement with previous inventories (0.91 and 1.13 Tg a-1 from Eyring et al. (2005a) and Wang et al. [2008]). Observed PM composition was 46% SO2<inf>4-</inf>, 39% OM, and 15% BC and differs from inventories that used 81%, 14%, and 5% and 31%, 63%, and 6% SO2<inf>4-</inf>, OM, and BC, respectively. SO2<inf>4</inf> and OM mass were found to be dependent on fuel sulfur content as were SSA, hygroscopicity, and CCN concentrations. BC mass was dependent on engine type and combustion efficiency. A plume evolution study conducted on one vessel showed conservation of particle light absorption, decrease in CN > 5 nm, increase in particle hygroscopicity, and an increase in average particle size with distance from emission. These results suggest emission of small nucleation mode particles that subsequently coagulate/condense onto larger BC and OM. This work contributes to an improved understanding of the impacts of ship emissions on climate and air quality and will also assist in determining potential effects of altering fuel standards. Copyright 2009 by the American Geophysical Union."
"57189998431;7003488532;8643088300;7003897194;7004510293;7004864963;","Low molecular weight organic acids in aerosol particles from Rondônia, Brazil, during the biomass-burning, transition and wet periods",2005,"10.5194/acp-5-781-2005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-16444370595&doi=10.5194%2facp-5-781-2005&partnerID=40&md5=83a64c8b65d688a85151aad25d787fe7","Particles from biomass burning and regional haze were sampled in Rondônia, Brazil, during dry, transition and wet periods from September to November 2002, as part of the LBA-SMOCC (Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke, Aerosols, Clouds, Rainfall, and Climate) field campaign. Water soluble organic and inorganic compounds in bulk (High Volume and Stacked Filter Unit sampler) and size-resolved (Micro Orifice Uniform Deposit Impactor - MOUDI) smoke samples were determined by ion chromatography. It was found that low molecular weight polar organic acids account for a significant fraction of the water soluble organic carbon (WSOC) in biomass burning aerosols (C2-C6 dicarboxylic acids reached up to 3.7% and one-ring aromatic acids reached up to 2% of fine fraction WSOC during burning period). Short dicarboxylic (C2-C6) acids are dominated by oxalic acid followed by malonic and succinic acids. The largest ionic species is ammonium sulfate (60-70% of ionic mass). It was found that most of the ionic mass is concentrated in submicrometer-sized particles. Based on the size distribution and correlations with K+, a known biomass burning tracer, it is suggested that many of the organic acids are directly emitted by vegetation fires. Concentrations of dicarboxylic acids in the front and back filters of high volume sampler were determined. Based on these measurements, it was concluded that in the neutral or slightly basic smoke particles typical of this region, dicarboxylic acids are mostly confined to the particulate phase. Finally, it is shown that the distribution of water soluble species shifts to larger aerosols sizes as the aerosol population ages and mixes with other aerosol types in the atmosphere. © 2005 Author(s). This work is licensed under a Creative Commons License."
"57201410408;7403326970;8323763900;6701732679;57203348817;7005813095;57215982632;26032065800;7201847605;6603871013;9940496700;6603770689;6602529898;16402575500;7005264401;","The terrain-induced rotor experiment",2008,"10.1175/2008BAMS2487.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-60149094246&doi=10.1175%2f2008BAMS2487.1&partnerID=40&md5=03edb2ad1555598a860734f7dc1b6bed","The Terrain-Induced Rotor Experiment (T-REX) is a coordinated international project, composed of an observational field campaign and a research program, focused on the investigation of atmospheric rotors and closely related phenomena in complex terrain. The T-REX field campaign took place during March and April 2006 in the lep of the southern Sierra Nevada in eastern California. Atmospheric rotors have been traditionally defined as quasi-two-dimensional atmospheric vortices that form parallel to and downwind of a mountain ridge under conditions conducive to the generation of large-amplitude mountain waves. Intermittency, high levels of turbulence, and complex small-scale internal structure characterize rotors, which are known hazards to general aviation. The objective of the T-REX field campaign was to provide an unprecedented comprehensive set of in situ and remotely sensed meteorological observations from the ground to UTLS altitudes for the documentation of the spatiotem-poral characteristics and internal structure of a tightly coupled system consisting of an atmospheric rotor, terrain-induced internal gravity waves, and a complex terrain boundary layer. In. addition, T-REX had several ancillary objectives including the studies of UTLS chemical distribution in the presence of mountain waves and complex-terrain boundary layer in the absence of waves and rotors. This overview provides a background of the project including the information on its science objectives, experimental design, and observational systems, along with highlights of key observations obtained during the field campaign. © 2008 American Meteorological Society."
"16308514000;6508259172;6602832585;6602974799;7003591311;6602715033;55438848700;7202050065;16206263100;6603684590;7101846027;7006572336;57196499374;","Oxalic acid in clear and cloudy atmospheres: Analysis of data from International Consortium for Atmospheric Research on Transport and Transformation 2004",2006,"10.1029/2005JD006880","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249876495&doi=10.1029%2f2005JD006880&partnerID=40&md5=0746b5d0a119c6e16a6c0a514bb85801","Oxalic acid is often the leading contributor to the total dicarboxylic acid mass in ambient organic aerosol particles. During the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign, nine inorganic ions (including SO<inf>4</inf>2-) and five organic acid ions (including oxalate) were measured on board the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter research aircraft by a particle-into-liquid sampler (PILS) during flights over Ohio and surrounding areas. Five local atmospheric conditions were studied: (1) cloud-free air, (2) power plant plume in cloud-free air with precipitation from scattered clouds overhead, (3) power plant plume in cloud-free air, (4) power plant plume in cloud, and (5) clouds uninfluenced by local pollution sources. The aircraft sampled from two inlets: a counterflow virtual impactor (CVI) to isolate droplet residuals in clouds and a second inlet for sampling total aerosol. A strong correlation was observed between oxalate and SO<inf>4</inf> 2- when sampling through both inlets in clouds. Predictions from a chemical cloud parcel model considering the aqueous-phase production of dicarboxylic acids and SO<inf>4</inf> 2- show good agreement for the relative magnitude of SO<inf>4</inf>2- and oxalate growth for two scenarios: power plant plume in clouds and clouds uninfluenced by local pollution sources. The relative contributions of the two aqueous-phase routes responsible for oxalic acid formation were examined; the oxidation of glyoxylic acid was predicted to dominate over the decay of longer-chain dicarboxylic acids. Clear evidence is presented for aqueous-phase oxalic acid production as the primary mechanism for oxalic acid formation in ambient aerosols. Copyright 2006 by the American Geophysical Union."
"6701549604;16185051500;7003667860;7004201807;7003997130;7006432091;6603585457;7007160862;6701432911;7201888941;7403077486;7004921990;","Improvement of microphysical parameterization through observational verification experiment",2003,"10.1175/BAMS-84-12-1807","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0242425302&doi=10.1175%2fBAMS-84-12-1807&partnerID=40&md5=81ef0bf5d8b84ab59323df6b250b0bfb","During the past several years, there was increasing evidence of deficiencies in bulk microphysical parameterizations in numerical weather prediction models. Improvements in these parameterizations were difficult because coincident and comprehensive measurements of both the basic-state flow and microphysical parameters were not available. In response to the need for such data, two field campaigns were carried out: an offshore frontal precipitation study off the Washington coast in January-February 2001, and an orographic precipitation study in the oregon Cascade mountains in November-December 2001."
"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."
"7004008609;8735921500;7004499877;7004713805;6508270710;7003765323;7202258620;6603392379;8899985400;7404592426;7102294773;7202180152;7405728922;","Evaluation of several PM2.5 forecast models using data collected during the ICARTT/NEAQS 2004 field study",2007,"10.1029/2006JD007608","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547607013&doi=10.1029%2f2006JD007608&partnerID=40&md5=a3a0b720d3967ef86d6ac2770713ab76","Real-time forecasts of PM2.5 aerosol mass from seven air quality forecast models (AQFMs) are statistically evaluated against observations collected in the northeastern United States and southeastern Canada from two surface networks and aircraft data during the summer of 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT)/New England Air Quality Study (NEAQS) field campaign. The AIRNOW surface network is used to evaluate PM2.5 aerosol mass, the U.S. EPA STN network is used for PM2.5 aerosol composition comparisons, and aerosol size distribution and composition measured from the NOAA P-3 aircraft are also compared. Statistics based on midday 8-hour averages, as well as 24-hour averages are evaluated against the AIRNOW surface network. When the 8-hour average PM2.5 Statistics are compared against equivalent ozone statistics for each model, the analysis shows that PM2.5 forecasts possess nearly equivalent correlation, less bias, and better skill relative to the corresponding ozone forecasts. An analysis of the diurnal variability shows that most models do not reproduce the observed diurnal cycle at urban and suburban monitor locations, particularly during the nighttime to early morning transition. While observations show median rural PM2.5 levels similar to urban and suburban values, the models display noticeably smaller rural/urban PM2.5 ratios. The ensemble PM2.5 forecast, created by combining six separate forecasts with equal weighting, is also evaluated and shown to yield the best possible forecast in terms of the statistical measures considered. The comparisons of PM2.5 composition with NOAA P-3 aircraft data reveals two important features: (1) The organic component of PM2.5 is significantly underpredicted by all the AQFMs and (2) those models that include aqueous phase oxidation of SO2 to sulfate in clouds overpredict sulfate levels while those AQFMs that do not include this transformation mechanism underpredict sulfate. Errors in PM2.5 ammonium levels tend to correlate directly with errors in sulfate. Comparisons of PM2.5 composition with the U.S. EPA STN network for three of the AQFMs show that sulfate biases are consistently lower at the surface than aloft. Recommendations for further research and analysis to help improve PM2.5 forecasts are also provided. Copyright 2007 by the American Geophysical Union."
"6701689811;35577097300;25926681100;6508063123;16686078100;","Climate implications of large warming by elevated aerosol over India",2008,"10.1029/2008GL034944","https://www.scopus.com/inward/record.uri?eid=2-s2.0-57749205583&doi=10.1029%2f2008GL034944&partnerID=40&md5=0a2e34f6562e7f0b97e0e405770db73e","Wide-ranging multi-platform data from a major field campaign conducted over Indian region was used to estimate the energy absorbed in ten layers of the atmosphere. We found that during pre-monsoon season, most of Indian region is characterized by elevated aerosol layers. Three-fold increase in aerosol extinction coefficient was observed at higher atmospheric layers (>2 km) compared to that near the surface and a substantial fraction (as much as 50 to 70%) of aerosol optical depth was found contributed by aerosols above (reflecting) clouds. Consequent absorption and hence strong warming above clouds was found larger by several degrees (K) compared to that near the surface. The aerosol-induced elevated warming was mostly confined below 2 km over northern Indian Ocean while found up to 4 km over central India, thus exhibiting strong meridional gradients (∼4 K) at atmospheric levels above 2 km. Climate implications of the large elevated warming are discussed. Copyright 2008 by the American Geophysical Union."
"7005793702;7005399437;7004299722;7004467879;","Measurements of irradiance attenuation and estimation of aerosol single scattering albedo for biomass burning aerosols in Amazonia",1998,"10.1029/98JD00399","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032573731&doi=10.1029%2f98JD00399&partnerID=40&md5=25153c48905590607e52ebc0edb06f22","Investigation of the effects of biomass burning aerosols on the surface irradiance were conducted as a part of the Smoke, Clouds, and Radiation - Brazil (SCAR-B) experiment during August - September 1995. Measurements of broadband and spectral irradiance, in conjuction with measurements of aerosol physical and optical properties (optical depth, phase function, and size distribution) were made under varying conditions of aerosol loading during the SCAR-B field campaign. Estimates of aerosol single scattering albedo (ωo) were made from matching of the measured irradiance values to the model computed irradiances by varying ωo, for observations made under cloudless conditions. Values of ωo, at approximately 550 nm, estimated from this technique using broadband 400-700 nm irradiance measurements, ranged from approximately 0.82 to 0.94 for the dates and times of these SCAR-B measurements. Utilizing spectral irradiance data, the model retrieved values of ωo decreased with increasing wavelength, with the change of ωo as a function of wavelength differing on different days. Reductions in photosynthetically active radiation (PAR; 400-700 nm) incident at the surface were computed to range from about 20 to 45% compared to background aerosol conditions for the 2 month biomass burning season at several locations in the southern Amazon Basin. These large reductions in incident PAR at the surface due to the heavy aerosol loadings could have implications for primary production of sensitive ecosystems. In addition, reductions of total incident solar radiation from aerosol direct radiative effects may have significant impact on reducing surface heating and increasing aerosol layer heating from absorption. Copyright 1998 by the American Geophysical Union."
"7201826462;7403931916;7005729142;7202057166;55710310300;6506385754;55545601500;56722821200;","Improvements in shortwave bulk scattering and absorption models for the remote sensing of ice clouds",2011,"10.1175/2010JAMC2608.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79959581814&doi=10.1175%2f2010JAMC2608.1&partnerID=40&md5=ecf9962b9d2542743e916d859b0da431","This study summarizes recent improvements in the development of bulk scattering/absorption models at solar wavelengths. The approach combines microphysical measurements from various field campaigns with single-scattering properties for nine habits including droxtals, plates, solid/hollow columns, solid/hollow bullet rosettes, and several types of aggregates. Microphysical measurements are incorporated from a number of recent field campaigns in both the Northern and Southern Hemisphere. A set of 12 815 particle size distributions is used for which Tcld ≤ -40°C. The ice water content in the microphysical data spans six orders of magnitude. For evaluation, a library of ice-particle single-scattering properties is employed for 101 wavelengths between 0.4 and 2.24 μm. The library includes the full phase matrix as well as properties for smooth, moderately roughened, and severely roughened particles. Habit mixtures are developed for generalized cirrus, midlatitude cirrus, and deep tropical convection. The single-scattering properties are integrated over particle size and wavelength using an assumed habit mixture to develop bulk scattering and absorption properties. In comparison with global Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) data, models built with severely roughened particles compare best for all habit mixtures. The assumption of smooth particles provided the largest departure from CALIOP measurements. The use of roughened rather than smooth particles to infer optical thickness and effective diameter from satellite imagery such as the Moderate Resolution Imaging Spectroradiometer (MODIS) will result in a decrease in optical thickness and an increase in particle size. © 2011 American Meteorological Society."
"35204036000;7601490850;55718320700;23766814900;51663607900;55532103900;","Spatial-temporal variations in surface ozone in Northern China as observed during 2009-2010 and possible implications for future air quality control strategies",2012,"10.5194/acp-12-2757-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863352807&doi=10.5194%2facp-12-2757-2012&partnerID=40&md5=ae78c5ce8e043c2db0b2f712205276fe","The Project of Atmospheric Combined Pollution Monitoring over Beijing and its Surrounding Areas, was an intensive field campaign conducted over Northern China between June 2009 and August 2011 to provide a comprehensive record of ozone (O 3) and nitrogen oxides (NO x) and contribute to an in-depth understanding of air pollution in Northern China and its driving forces. In this campaign, 25 stations in an air-quality monitoring network provided regional-scale spatial coverage. In this study, we analyzed the data on O3 and NO x levels obtained at 22 sites (out of 25 sites due to data availability) over Northern China between 1 September 2009 and 31 August 2010. Our goal was to investigate the O 3 spatial-temporal variations and control strategy in this area. Significant diurnal and seasonal variations were noted, with the highest concentrations typically found at around 03:00 p.m. (local time) and in June. The lowest concentrations were generally found during early morning hours (around 06:00 a.m.) and in December. Compared with July and August, June has increased photochemical production due to decreased cloud cover coupled with reduced O3 loss due to less dry deposition, inducing an O 3 peak appearing in June. The averaged O 3 concentrations were lower in the plains area compared with the mountainous area due to the titration effects of high NO x emissions in urban areas. When the characteristics of O 3 pollution in different regions were distinguished by factor analysis, we found high levels of O 3 that exceeded China's National Standard throughout the plains, especially over Beijing and the surrounding areas. An integrated analysis with emissions data, meteorological data, and topography over Northern China found that the meteorological conditions were the main factors that dominated the spatial variations of O 3, with the presence of abundant emissions of precursors in this area. The smog production algorithm and space-based HCH O/NO 2 column ratio were used to show the O 3-NO x-VOC s sensitivity and examine the control strategy of O 3 over Northern China. The results show that summer O 3 production in the plains and northern mountainous areas was sensitive to VOC s and NOx, respectively. The presented results are intended to provide guidance for redefining government strategies to control the photochemical formation of air pollutants over Northern China and are relevant for developing urban agglomerations worldwide. © Author(s) 2012. CC Attribution 3.0 License."
"7202154370;7407104838;7201706659;7004942632;7004034323;7404240633;","An observational and theoretical study of the radiative properties of cirrus: Some results from ICE'89",1994,"10.1002/qj.49712051804","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028581066&doi=10.1002%2fqj.49712051804&partnerID=40&md5=bc34cd368d90835365c4419ebbb9ab9a","Observations of the microphysical and radiative properties of two cirrus clouds are reported. The measurements were taken from the C‐130 aircraft of the UK Meteorological Research Flight as part of the field campaign of the International Cirrus Experiment, ICE'89. Cirrus microphysical properties are analysed in terms of ice water content and a suitably defined ice crystal ‘effective radius’. Estimates of the ice water content are derived from both a standard Particle Measuring Systems 2D‐C cloud probe and a Lyman‐α total water content (TWC) hygrometer. With both flights large discrepancies are seen to occur between the two instruments near the cloud base and top, with the ice water contents derived from the TWC probe being consistently greater than those from the 2D‐C probe. Evidence is presented which suggests that the differences near the cloud base are due to a significant number of large (&gt;800 μm) crystals, which the 2D‐C probe is unable to sample. Near the cloud top the differences are assumed to be due to small (&lt;100μm) crystals, which the 2D‐C probe is again unable to sample correctly. Thus more weight has been given to the TWC probe measurements of ice water content, with the measurements of ice crystal effective radius being adjusted accordingly. Model clouds, constructed from the microphysical measurements, are used as input to a number of radiation parametrizations, both in the long‐wave and short‐wave regions of the spectrum. In the long wave, model agreement with both narrow‐band and broad‐band measurements is reasonably good, although discrepancies exist near the cloud tops. Some evidence is presented which suggests that the measured effective radii from one of the flights are too large to explain the radiative characteristics of the cloud. The effect of long‐wave scattering is shown to be small. The inferred long‐wave broad‐band mass‐absorption coefficient varies between 0.002 m2g‐1 and 0.087 m2g−1, and it shows a marked inverse dependence on the ice crystal effective radius, as anticipated by simple theoretical calculations. In the short wave, agreement between the measured irradiances and those computed using several parametrizations is again reasonably good, although limited by the natural variability of the clouds. The net radiation budgets of both cloud layers are analysed, and the possibility of the existence of a relationship between ice water content and effective radius is considered. Copyright © 1994 Royal Meteorological Society"
"7003568823;7102051256;7201847605;7404195755;","Mountaintop and radar measurements of anthropogenic aerosol effects on snow growth and snowfall rate",2003,"10.1029/2002gl016855","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041782101&doi=10.1029%2f2002gl016855&partnerID=40&md5=1dc00220b7998982356f446e4c64aa5f","A field campaign designed to investigate the second indirect aerosol effect (reduction of precipitation by anthropogenic aerosols which produce more numerous and smaller cloud droplets) was conducted during winter in the northern Rocky Mountains of Colorado. Combining remote sensing and in-situ mountain-top measurements it was possible to show higher concentrations of anthropogenic aerosols (∼1 μg m-3) altered the microphysics of the lower orographic feeder cloud to the extent that the snow particle rime growth process was inhibited, or completely shut off, resulting in lower snow water equivalent precipitation rates."
"7102913661;7005902263;7006372688;7005461477;7401850582;6602743250;7102965584;6701640417;7103008628;7005054220;8916335600;35396858200;34568423700;7003597162;7004165697;6602221672;57200319386;8261329600;15080710300;6506458269;7003468369;7102336894;55218162500;35393120300;26531406100;35307051000;16301396200;57203776263;7202119915;16480316200;6603178707;37040691400;56187234400;16402575500;16480965400;36616603800;7402185841;7005016308;7004643405;56187256200;14048087800;6701691393;55925502100;7003479494;7006497590;6602356428;57205497099;7101827324;","The deep convective clouds and chemistry (DC3) field campaign",2015,"10.1175/BAMS-D-13-00290.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942195471&doi=10.1175%2fBAMS-D-13-00290.1&partnerID=40&md5=8d1caeabf24a26e47d2fc4935295f434","The Deep Convective Clouds and Chemistry (DC3) field experiment produced an exceptional dataset on thunderstorms, including their dynamical, physical, and electrical structures and their impact on the chemical composition of the troposphere. The field experiment gathered detailed information on the chemical composition of the inflow and outflow regions of midlatitude thunderstorms in northeast Colorado, west Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the upper-tropospheric convective plume. These data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, chemistry in the upper troposphere that is affected by the convection, and related source characterization of the three sampling regions. DC3 also documented biomass-burning plumes and the interactions of these plumes with deep convection. © 2015 American Meteorological Society."
"22953153500;24398842400;55942083800;24458137900;","Ice nuclei in marine air: Biogenic particles or dust?",2013,"10.5194/acp-13-245-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84872258850&doi=10.5194%2facp-13-245-2013&partnerID=40&md5=7a913ff578d5c0dc4e22fd437469108a","Ice nuclei impact clouds, but their sources and distribution in the atmosphere are still not well known. Particularly little attention has been paid to IN sources in marine environments, although evidence from field studies suggests that IN populations in remote marine regions may be dominated by primary biogenic particles associated with sea spray. In this exploratory model study, we aim to bring attention to this long-neglected topic and identify promising target regions for future field campaigns. We assess the likely global distribution of marine biogenic ice nuclei using a combination of historical observations, satellite data and model output. By comparing simulated marine biogenic immersion IN distributions and dust immersion IN distributions, we predict strong regional differences in the importance of marine biogenic IN relative to dust IN. Our analysis suggests that marine biogenic IN are most likely to play a dominant role in determining IN concentrations in near-surface-air over the Southern Ocean, so future field campaigns aimed at investigating marine biogenic IN should target that region. Climate-related changes in the abundance and emission of biogenic marine IN could affect marine cloud properties, thereby introducing previously unconsidered feedbacks that influence the hydrological cycle and the Earth's energy balance. Furthermore, marine biogenic IN may be an important aspect to consider in proposals for marine cloud brightening by artificial sea spray production. © 2013 Author(s)."
"8511991900;7202048112;7409080503;7103158465;57138743300;35114405700;55802246600;57200702127;","Aerosol impacts on clouds and precipitation in eastern China: Results from bin and bulk microphysics",2012,"10.1029/2011JD016537","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863012201&doi=10.1029%2f2011JD016537&partnerID=40&md5=b9a38f1a075d2a0096793d34f934df7f","Using the Weather Research and Forecasting model coupled with a spectral-bin microphysics (""SBM"") and measurements from the Atmospheric Radiation Measurement Mobile Facility field campaign in China (AMF-China), the authors examine aerosol indirect effects (AIE) in the typical cloud regimes of the warm and cold seasons in Southeast China: deep convective clouds (DCC) and stratus clouds (SC), respectively. Comparisons with a two-moment bulk microphysics (""Bulk"") are performed to gain insights for improving bulk schemes in estimating AIE in weather and climate simulations. For the first time, measurements of aerosol and cloud properties acquired in China are used to evaluate model simulations to better understand aerosol impact on clouds in the southeast of China. It is found that changes in cloud condensation nuclei (CCN) concentration significantly change the timing of storms, the spatial and temporal distributions of precipitation, the frequency distribution of precipitation rate, as well as cloud base and top heights for the DCC, but not for the SC. Increasing CCN increases cloud droplet number (N<inf>c</inf>) and mass concentrations, decreases raindrop number concentration, and delays the onset of precipitation. Compared with SBM, Bulk predicts much higher N<inf>c</inf> and the opposite CCN effects on convection and heavy rain, stemming from the fixed CCN prescribed in Bulk. CCN have a significant effect on ice microphysical properties with SBM but not Bulk and different condensation/deposition freezing parameterizations employed could be the main reason. This study provided insights to further improve the bulk scheme to better account for aerosol-cloud interactions in regional and global climate simulations, which will be the focus for a follow-on paper. Copyright 2012 by the American Geophysical Union."
"35768617200;7006717176;6701339904;","CALIPSO detection of an Asian tropopause aerosol layer",2011,"10.1029/2010GL046614","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955026963&doi=10.1029%2f2010GL046614&partnerID=40&md5=43f3f4363d00164d3862fc3a2e3a372d","The first four years of the CALIPSO lidar measurements have revealed the existence of an aerosol layer at the tropopause level associated with the Asian monsoon season in June, July and August. This Asian Tropopause Aerosol Layer (ATAL) extends geographically from Eastern Mediterranean (down to North Africa) to Western China (down to Thailand), and vertically from 13 to 18 km. The Scattering Ratio inferred from CALIPSO shows values between 1.10-1.15 on average with associated depolarization ratio of less than 5%. The Gaussian distribution of the points indicates that the mean value is statistically driven by an enhancement of the background aerosol level and not by episodic events such as a volcanic eruption or cloud contamination. Further satellite observations of aerosols and gases as well as field campaigns are urgently needed to characterize this layer, which is likely to be a significant source of non-volcanic aerosols for the global upper troposphere with a potential impact on its radiative and chemical balance. Copyright 2011 by the American Geophysical Union."
"8318166100;12782193000;52464886600;7003316308;55483250800;7401758587;","Validation of ETWatch using field measurements at diverse landscapes: A case study in Hai Basin of China",2012,"10.1016/j.jhydrol.2012.02.043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859437926&doi=10.1016%2fj.jhydrol.2012.02.043&partnerID=40&md5=8dca77b39cad105a0a0a9850d3a0e0ac","The latent heat of evapotranspiration (ET) plays an important role for water resource management in water scarcity areas. Compared to the water balance method or to in situ measurements, an operational integrated monitoring method of regional surface ET from remote sensing data is a potentially useful approach to achieve water saving. This study presents new algorithms for the aerodynamic roughness length for complex landscape, for gap filling for cloud days, and for data fusion at different resolutions, based on the Penman-Monteith equation. It also presents an improved algorithm for ET calculation with remotely sensed data for clear days. Algorithms were integrated into the ETWatch. The research objective was to present the enhanced features of the ETWatch algorithm and its validation in the 320,000km 2 Hai Basin in Northern China. This area faces serious over-exploitation of groundwater. ET was modeled and extensive field campaigns were done to collect data on soil moisture depletion, lysimeter measurements, eddy covariance measurements, and water balance calculations at diverse landscapes. The overall deviation for individual fields on a seasonal basis was 12% and decreased to 6% for an annual cycle. For larger areas, the deviation was 3% for an annual cycle. These levels of deviation are within the error bands for in situ measurements. The study concludes that data sets from ETWatch are able to aid consumptive water use reduction management in the study area. © 2012 Elsevier B.V."
"8927405700;36620394700;24366038500;6603611663;6701697023;55933600200;7003375617;8705440100;6507981312;10141225800;7801401670;6701490421;6508290106;7003414581;","The automated multiwavelength Raman polarization and water-vapor lidar PollyXT: The neXT generation",2016,"10.5194/amt-9-1767-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966706757&doi=10.5194%2famt-9-1767-2016&partnerID=40&md5=ba723eb81bb80f99a4b87b165b469eca","The atmospheric science community demands autonomous and quality-assured vertically resolved measurements of aerosol and cloud properties. For this purpose, a portable lidar called Polly was developed at TROPOS in 2003. The lidar system was continuously improved with gained experience from the EARLINET community, involvement in worldwide field campaigns, and international institute collaborations within the last 10 years. Here we present recent changes of the setup of the portable multiwavelength Raman and polarization lidar PollyXT and discuss the improved capabilities of the system by means of a case study. The latest system developments include an additional near-range receiver unit for Raman measurements of the backscatter and extinction coefficient down to 120 m above ground, a water-vapor channel, and channels for simultaneous measurements of the particle linear depolarization ratio at 355 and 532 nm. Quality improvements were achieved by systematically following the EARLINET guidelines and the international PollyNET quality assurance developments. A modified ship radar ensures measurements in agreement with air-traffic safety regulations and allows for 24/7 monitoring of the atmospheric state with PollyXT. © Author(s) 2016."
"7201432984;57189585133;11440963500;7005809959;57203200427;7102294773;7403682442;6602244257;57208698992;7103206141;57213358341;26427744500;6701636053;14035836100;6603735912;7005088845;7006708207;7006634316;7102604282;7202429440;7101959920;7004898221;55207447000;7003359002;7404592426;7403384594;23493942300;","Aerosol direct radiative effects over the northwest Atlantic, northwest Pacific, and North Indian Oceans: Estimates based on in-situ chemical and optical measurements and chemical transport modeling",2006,"10.5194/acp-6-1657-2006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746890915&doi=10.5194%2facp-6-1657-2006&partnerID=40&md5=5c3ea6726fda86dcd83d54d727145262","The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions (IPCC, 2001). Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predictions of future climate change for assumed emission scenarios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of atmospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regionsdownwind of major urban/population centers (North Indian Ocean (NIO) during INDOEX, the Northwest Pacific Ocean (NWP) during ACE-Asia, and the Northwest Atlantic Ocean (NWA) during ICARTT), incorporates understanding gained from field observations of aerosol distributions and properties into calculations of perturbations in radiative fluxes due to these aerosols. This study evaluates the current state of observations and of two chemical transport models (STEM and MOZART). Measurements of burdens, extinction optical depth (AOD), and direct radiative effect of aerosols (ORE - change in radiative flux due to total aerosols) are used as measurement-model check points to assess uncertainties. ln-situ measured and remotely sensed aerosol properties for each region (mixing state, mass scattering efficiency, single scattering albedo, and angular scattering properties and their dependences on relative humidity) are used as input parameters to two radiative transfer models (GFDL and Universityof Michigan) to constrain estimates of aerosol radiative effects, with uncertainties in each step propagated through the analysis. Constraining the radiative transfer calculations by observational inputs increases the clear-sky, 24-h averaged AOD (34×8%), top of atmosphere (TOA) DRE (32×12%), and TOA direct climate forcing of aerosols (DCF - change in radiative flux due to anthropogenic aerosols) (37×7%) relative to values obtained with ""a priori"" parameterizations of aerosol loadings and properties (GFDL RTM). The resulting constrained clear-sky TOA DCF is -3.3×0.47, -14×2.6, -6.4×2.1 Wm-2 for the NIO, NWP, and NWA, respectively. With the use of constrained quantities (extensive and intensive parameters) the calculated uncertainty in DCF was 25% less than the ""structural uncertainties"" used in the IPCC-2001 global estimates of direct aerosol climate forcing. Such comparisons with observations and resultant reductions in uncertainties are essential for improving and developing confidence in climate model calculations incorporating aerosol forcing."
"25647134900;57203052274;7003386805;57192695511;7003359002;35396858200;7403682442;7006686129;6602582342;7403384594;","Synthesis of satellite (MODIS), aircraft (ICARTT), and surface (IMPROVE, EPA-AQS, AERONET) aerosol observations over eastern North America to improve MODIS aerosol retrievals and constrain surface aerosol concentrations and sources",2010,"10.1029/2009JD012629","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955214338&doi=10.1029%2f2009JD012629&partnerID=40&md5=f394a50973046ac117dde8c0ab3567ae","We use an ensemble of satellite (MODIS), aircraft, and ground-based aerosol observations during the ICARTT field campaign over eastern North America in summer 2004 to (1) examine the consistency between different aerosol measurements, (2) evaluate a new retrieval of aerosol optical depths (AODs) and inferred surface aerosol concentrations (PM<inf>2.5</inf>) from the MODIS satellite instrument, and (3) apply this collective information to improve our understanding of aerosol sources. The GEOS-Chem global chemical transport model (CTM) provides a transfer platform between the different data sets, allowing us to evaluate the consistency between different aerosol parameters observed at different times and locations. We use an improved MODIS AOD retrieval based on locally derived visible surface reflectances and aerosol properties calculated from GEOS-Chem. Use of GEOS-Chem aerosol optical properties in the MODIS retrieval not only results in an improved AOD product but also allows quantitative evaluation of model aerosol mass from the comparison of simulated and observed AODs. The aircraft measurements show narrower aerosol size distributions than those usually assumed in models, and this has important implications for AOD retrievals. Our MODIS AOD retrieval compares well to the ground-based AERONET data (R = 0.84, slope = 1.02), significantly improving on the MODIS c005 operational product. Inference of surface PM<inf>2.5</inf> from our MODIS AOD retrieval shows good correlation to the EPA-AQS data (R = 0.78) but a high regression slope (slope = 1.48). The high slope is seen in all AOD-inferred PM<inf>2.5</inf> concentrations (AERONET: slope = 2.04; MODIS c005: slope = 1.51) and could reflect a clear-sky bias in the AOD observations. The ensemble of MODIS, aircraft, and surface data are consistent in pointing to a model overestimate of sulfate in the mid-Atlantic and an underestimate of organic and dust aerosol in the southeastern United States. The sulfate overestimate could reflect an excessive contribution from aqueous-phase production in clouds, while the organic carbon underestimate could possibly be resolved by a new secondary pathway involving dicarbonyls.Copyright 2010 by the American Geophysical Union."
"7403276033;6602499262;34977671700;7102428780;6507864329;6507069695;","NO2 column amounts from ground-based Pandora and MFDOAS spectrometers using the direct-sun DOAS technique: Intercomparisons and application to OMI validation",2009,"10.1029/2009jd011848","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349309942&doi=10.1029%2f2009jd011848&partnerID=40&md5=4ed1515131a9d855911a7728ef24902a","Vertical column amounts of nitrogen dioxide, C(NO2), are derived from ground-based direct solar irradiance measurements using two new and independently developed spectrometer systems, Pandora (Goddard Space Flight Cen 1ter) and MFDOAS (Washington State University). We discuss the advantages of C(NO2) retrievals based on Direct Sun - Differential Optical Absorption Spectroscopy (DS-DOAS). The C(NO2) data are presented from field campaigns using Pandora at Aristotle University (AUTH), Thessaloniki, Greece; a second field campaign involving both new instruments at Goddard Space Flight Center (GSFC), Greenbelt, Maryland; a Pandora time series from December 2006 to October 2008 at GSFC; and a MFDOAS time series for spring 2008 at Pacific Northwest National Laboratory (PNNL), Richland, Washington. Pandora and MFDOAS were compared at GFSC and found to closely agree, with both instruments having a clear-sky precision of 0.01 DU (1 DU = 2.67 x 1016 molecules/cm 2) and a nominal accuracy of 0.1 DU. The high precision is obtained from careful laboratory characterization of the spectrometers (temperature sensitivity, slit function, pixel to pixel radiometric calibration, and wavelength calibration), and from sufficient measurement averaging to reduce instrument noise. The accuracy achieved depends on laboratory-measured absorption cross sections and on spectrometer laboratory and field calibration techniques used at each measurement site. The 0.01 DU precision is sufficient to track minute-by-minute changes in C(NO2) throughout each day with typical daytime values ranging from 0.2 to 2 DU. The MFDOAS instrument has better noise ' characteristics for a single measurement, which permits MFDOAS to operate at higher time resolution than Pandora for the same precision. Because Pandora and MFDOAS direct-sun measurements can be made in the presence of light to moderate clouds, but with reduced precision (~0.2 DU for moderate cloud cover), a nearly continuous record can be obtained, which is important when matching OMI overpass times for satellite data validation. Comparisons between Pandora and MFDOAS with OMI are discussed for the moderately polluted GSFC site, between Pandora and OMI at the AUTH site, and between MFDOAS and OMI at the PNNL site. Validation of OMI measured C(NO2) is essential for the scientific use of the satellite data for air quality, for atmospheric photolysis and chemistry, and for retrieval of other quantities (e.g., accurate atmospheric correction for satellite estimates of ocean reflectance and bio-optical properties). Changes in the diurnal variability of C(NO2) with season and day of the week are presented based on the 2-year time series at GSFC measured by the Pandora instrument. Copyright 2009 by the American Geophysical Union."
"24537168200;57190606134;7006377579;7006837187;7003329635;7006593624;7004296083;35461255500;57191583856;8208591500;7006712143;","Size and composition measurements of background aerosol and new particle growth in a Finnish forest during QUEST 2 using an Aerodyne Aerosol Mass Spectrometer",2006,"10.5194/acp-6-315-2006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33645636983&doi=10.5194%2facp-6-315-2006&partnerID=40&md5=50904d95553b579f0ce19d00d6f80c61","The study of the growth of nucleation-mode particles is important, as this prevents their loss through diffusion and allows them to reach sizes where they may become effective cloud condensation nuclei. Hyytiälä, a forested site in southern Finland, frequently experiences particle nucleation events during the spring and autumn, where particles first appear during the morning and continue to grow for several hours afterwards. As part of the QUEST 2 intensive field campaign during March and April 2003, an Aerodyne Aerosol Mass Spectrometer (AMS) was deployed alongside other aerosol instrumentation to study the particulate composition and dynamics of growth events and characterise the background aerosol. Despite the small mass concentrations, the AMS was able to distinguish the grown particles in the <100 nm regime several hours after an event and confirm that the particles were principally organic in composition. The AMS was also able to derive a mass spectral fingerprint for the organic species present, and found that it was consistent between events and independent of the mean particle diameter during non-polluted cases, implying the same species were also condensing onto the accumulation mode. The results were compared with those from offline analyses such as GC-MS and were consistent with the hypothesis that the main components were alkanes from plant waxes and the oxidation products of terpenes. © 2006 Author(s). This work is licensed under a Creative Commons License."
"7201826462;6603685334;7403931916;35985515200;7407116104;6506716686;7101899854;","Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS: 1. Data and models",2000,"10.1029/1999JD901089","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033792504&doi=10.1029%2f1999JD901089&partnerID=40&md5=68deedc6d0b24dd7522ce26a4085982e","We investigate methods to infer cloud properties such as cloud optical thickness, thermodynamic phase, cloud particle size, and cloud overlap by comparing cloud and clear-sky radiative transfer computations to measurements provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) airborne simulator (MAS). The MAS scanning spectroradiometer was flown on the NASA ER-2 during the Subsonic Aircraft Contrail and Cloud Effects Special Study (SUCCESS) field campaign during April and May 1996. The MAS bands chosen for this study correspond to wavelengths of 0.65, 1.63, 1.90, 2.15, 3.82, 8.52, 11, and 12 μm. Clear-sky absorption due to water vapor, ozone, and other trace gases is calculated using a set of correlated k-distribution routines developed specifically for these MAS bands. Scattering properties (phase function, single-scattering albedo, and extinction cross section) are derived for water droplet clouds using Mie theory. Scattering properties for ice-phase clouds are incorporated for seven cirrus models: cirrostratus, cirrus uncinus, cold cirrus, warm cirrus, and cirrus at temperatures of T = -20°C, -40°C, and -60°C. The cirrus are composed of four crystal types: hexagonal plates, two-dimensional bullet rosettes, hollow columns, and aggregates. Results from comparison of MAS data from a liquid water cloud with theoretical calculations indicate that estimates of optical thickness and particle size are reasonably consistent with one another no matter which spectral bands are used in the analysis. However, comparison of MAS data from a cirrus cloud with theoretical calculations shows consistency in optical thickness but not with particle size among the various band combinations used in the analysis. The methods described in this paper are used in two companion papers to explore techniques to infer cloud thermodynamic phase and cloud overlap."
"36611965700;7404061081;7006421484;7004174939;7005399437;35501613900;7004166136;7003729315;","MODIS 3 km aerosol product: Applications over land in an urban/suburban region",2013,"10.5194/amt-6-1747-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880850114&doi=10.5194%2famt-6-1747-2013&partnerID=40&md5=6d8a44e35d01e195ef8e6a4ccaef569f","MODerate resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua satellites have provided a rich dataset of aerosol information at a 10 km spatial scale. Although originally intended for climate applications, the air quality community quickly became interested in using the MODIS aerosol data. However, 10 km resolution is not sufficient to resolve local scale aerosol features. With this in mind, MODIS Collection 6 includes a global aerosol product with a 3 km resolution. Here, we evaluate the 3 km product over the Baltimore-Washington D.C., USA, corridor during the summer of 2011 by comparing with spatially dense aerosol data measured by airborne High Spectral Resolution Lidar (HSRL) and a network of 44 sun photometers (SP) spaced approximately 10 km apart, collected as part of the DISCOVER-AQ field campaign. The HSRL instrument shows that AOD can vary by over 0.2 within a single 10 km MODIS pixel, meaning that higher resolution satellite retrievals may help to better characterize aerosol spatial distributions in this region. Different techniques for validating a high-resolution aerosol product against SP measurements are considered. Although the 10 km product is more statistically reliable than the 3 km product, the 3 km product still performs acceptably with nearly two-thirds of MODIS/SP collocations falling within an expected error envelope with high correlation (R 0.90), although with a high bias of ∼ 0.06. The 3 km product can better resolve aerosol gradients and retrieve closer to clouds and shorelines than the 10 km product, but tends to show more noise, especially in urban areas. This urban degradation is quantified using ancillary land cover data. Overall, we show that the MODIS 3 km product adds new information to the existing set of satellite derived aerosol products and validates well over the region, but due to noise and problems in urban areas, should be treated with some degree of caution. © 2012 Author(s)."
"7003406689;7103400568;6506385754;7005729142;7004399029;7102643810;7006874359;","Microphysical observations of tropical clouds",2002,"10.1175/1520-0450(2002)041<0097:MOOTC>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036321203&doi=10.1175%2f1520-0450%282002%29041%3c0097%3aMOOTC%3e2.0.CO%3b2&partnerID=40&md5=72e54811efb4f2f6de5da60af666453f","The results from airborne in situ sampling of convective tropical storms in the Amazon and Kwajalein are presented. Three cases from the Amazon and two from Kwajalein are compared and provide examples of the much larger dataset that was obtained from field campaigns in these two regions during 1999. The strength of the updraft was a major factor in determining the microphysical characteristics of hydrometeors. Weak updrafts exhibited a well-developed warm rain process by the time droplets had reached the freezing level. Stronger updrafts (&gt;5 m s-1) contained smaller droplets or ice particles at cloud midlevels than regions with the weaker updrafts. Significant supercooled liquid water was found only at temperatures warmer than - 12°C, although traces of liquid water were observed at temperatures as cold as - 18°C. In deep stratiform anvil regions, aggregation was observed to be a major growth mechanism. These clouds did not contain appreciable amounts of supercooled water. Clouds with similar updrafts in the Amazon and Kwajalein exhibited similar particle types and concentrations. The implications of these results for current Tropical Rainfall Measuring Mission (TRMM) investigations are discussed."
"7003999574;7005361537;7006544721;7005560252;8950640300;8608660400;6701463335;7501381728;7403143315;6506643480;10939473600;15926418500;8437866600;7006705580;7005444075;55720332500;7003430284;7004027519;","Characterization of a large biogenic secondary organic aerosol event from eastern Canadian forests",2010,"10.5194/acp-10-2825-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952966524&doi=10.5194%2facp-10-2825-2010&partnerID=40&md5=fa0b8d30d5a914735308d5a147ca3b44","Measurements of aerosol composition, volatile organic compounds, and CO are used to determine biogenic secondary organic aerosol (SOA) concentrations at a rural site 70 km north of Toronto. These biogenic SOA levels are many times higher than past observations and occur during a period of increasing temperatures and outflow from Northern Ontario and Quebec forests in early summer. A regional chemical transport model approximately predicts the event timing and accurately predicts the aerosol loading, identifying the precursors as monoterpene emissions from the coniferous forest. The agreement between the measured and modeled biogenic aerosol concentrations contrasts with model underpredictions for polluted regions. Correlations of the oxygenated organic aerosol mass with tracers such as CO support a secondary aerosol source and distinguish biogenic, pollution, and biomass burning periods during the field campaign. Using the Master Chemical Mechanism, it is shown that the levels of CO observed during the biogenic event are consistent with a photochemical source arising from monoterpene oxidation. The biogenic aerosol mass correlates with satellite measurements of regional aerosol optical depth, indicating that the event extends across the eastern Canadian forest. This regional event correlates with increased temperatures, indicating that temperature-dependent forest emissions can significantly affect climate through enhanced direct optical scattering and higher cloud condensation nuclei numbers. © Author(s) 2010."
"7005054220;57192810488;7101638253;7006107946;7202710481;7402353721;57195465956;","Model calculations of troposhperic ozone production potential following observed convective events",1990,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025656788&partnerID=40&md5=6807d525e2c10e5d6a0fb2b6ebcaf972","Observations were made during a 1985 field campaign over the rural S-central US. Meteorological data and measurements of CO, NO, NOy, O3, and hydrocarbons were collected in air surrounding and inside clouds during and immediately following cloud convection. A one-dimensional photochemical model has been used to calculate O3 production potential before and after cloud redistribution of O3 precursor gases. Four distinct types of convective events have been analyzed. A comparison of trace gas profiles measured in and around a large cumulonimbus during dissipation shows O3 production in the upper troposphere may be increased fourfold by convection relative to undisturbed air. -from Authors"
"13607461800;6603409139;7004142910;7202607188;7404062492;57203053317;14049331400;7003314595;56184892000;6701762451;6506539438;57192107995;7202586843;7102011023;","Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect",2006,"10.5194/acp-6-3115-2006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746608879&doi=10.5194%2facp-6-3115-2006&partnerID=40&md5=8da8ce57813788a61a2caf41ebfb91f9","Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric) have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD) acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2 and 5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ∼50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as -0.3 Wm-2."
"7004292082;7006211890;7003535176;7102862273;6603314636;6603343882;7004843229;55684491100;","Water vapour measurements inside cirrus clouds in Northern and Southern hemispheres during INCA",2002,"10.1029/2001gl014440","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037104957&doi=10.1029%2f2001gl014440&partnerID=40&md5=6c39ab2d47dd0e3ad47fdee846e90f0a","Water vapour data inside cirrus clouds from in-situ measurements with an aircraft-borne frost-point hygrometer are analysed. These data have been obtained during two field campaigns, performed in the Southern and Northern hemisphere mid latitudes. There were many occurrences of ice supersaturation inside the investigated cirrus, with a higher frequency of occurrences in the Southern Hemisphere. The source of the differences in the humidity data from the two hemispheres is not clear, and it is speculated that these differences may be related to different levels of pollution. A distribution law for the relative humidity inside cirrus clouds is inferred."
"57190244589;6601942466;7005821395;6602238735;56256037700;7005893321;","Formic, acetic, oxalic, malonic and succinic acid concentrations and their contribution to organic carbon in cloud water",2002,"10.1016/S1352-2310(01)00573-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036496604&doi=10.1016%2fS1352-2310%2801%2900573-8&partnerID=40&md5=bfcba2b1909b4b17cda6c3db036179c4","The carbon content of cloud water at a continental background site in Austria was studied during two intensive field campaigns in spring 1999 and 2000. Six carboxylic acids, total (TC) and black (BC) carbon as well as major inorganic ions were determined. Organic carbon (OC) was calculated as the difference between TC and BC. The most abundant carboxylic acids were acetic (average: 0.93 μgml-1) and formic (0.61) followed by oxalic (0.38), succinic (0.15) and malonic (0.20) acids. Pyruvic acid was below the detection limit (&lt;0.08) in all samples. The BC concentration was 1.15 and OC 4.81 μgml-1 on average. Relating carboxylic acid concentrations to OC, the monocarboxylic acids alone represent 9.3% of OC. Adding the dicarboxylic acids, this average value increases to 11%. Although they are major components, no general trend could be seen between carboxylic acid and OC concentrations. © 2002 Elsevier Science Ltd. All rights reserved."
"35577097300;15846270900;8836278700;6701689811;","Spatial and vertical heterogeneities in aerosol properties over oceanic regions around india: Implications for radiative forcing",2009,"10.1002/qj.525","https://www.scopus.com/inward/record.uri?eid=2-s2.0-74849139258&doi=10.1002%2fqj.525&partnerID=40&md5=ddd5ad0f946857184b78b27903566bd9","The influence of atmospheric aerosols on Earth's radiation budget and hence climate, though well recognized and extensively investigated in recent years, remains largely uncertain mainly because of the large spatio-temporal heterogeneity and the lack of data with adequate resolution. To characterize this diversity, a major multi-platform field campaign ICARB (Integrated Campaign for Aerosols, gases and Radiation Budget) was carried out during the pre-monsoon period of 2006 over the Indian landmass and surrounding oceans, which was the biggest such campaign ever conducted over this region. Based on the extensive and concurrent measurements of the optical and physical properties of atmospheric aerosols during ICARB, the spatial distribution of aerosol radiative forcing was estimated over the entire Bay of Bengal (BoB), northern Indian Ocean and Arabian Sea (AS) as well as large spatial variations within these regions. Besides being considerably lower than the mean values reported earlier for this region, our studies have revealed large differences in the forcing components between the BoB and the AS. While the regionally averaged aerosol-induced atmospheric forcing efficiency was 31 ± 6 W m-2 τ-1 for the BoB, it was only ∼18 ± 7 W m-2 τ-1 for the AS. Airborne measurements revealed the presence of strong, elevated aerosol layers even over the oceans, leading to vertical structures in the atmospheric forcing, resulting in significant warming in the lower troposphere. These observations suggest serious climate implications and raise issues ranging from the impact of aerosols on vertical thermal structure of the atmospheric and hence cloud formation processes to monsoon circulation. © 2009 Royal Meteorological Society."
"6701850538;7004479957;35584010200;","Mesoscale variability and drizzle in southeast Pacific stratocumulus",2005,"10.1175/JAS3567.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-27744519094&doi=10.1175%2fJAS3567.1&partnerID=40&md5=6b72ba8648976f1737578bf2ba18b123","Observations from the East Pacific Investigation of Climate (EPIC) 2001 field campaign are well suited for exploring the relationships among the diurnal cycle, mesoscale (10-100 km) structure, and precipitation in the stratocumulus region in the southeast Pacific. Meteorological time series and observations from a scanning C-band radar, vertically pointing cloud radar, and ceilometer, as well as satellite data, are used to show that drizzle is associated with increased variability in cloud and boundary layer properties compared to nondrizzling periods. The stratocumulus-topped boundary layer is typically well mixed at night, transitioning to less well mixed in the afternoon, with drizzle most frequently occurring in the early morning. Coherent patches of drizzle, or ""cells,"" can have large areas with radar reflectivities of greater than 5 dBZ of up to about 100 km2. Individual cells have long lifetimes, up to 2 h, and appear to be replenished by moisture in the boundary layer. © 2005 American Meteorological Society."
"8937358400;7005054220;6701413579;56361419400;7003406689;7103400568;16834131000;57198015872;","A cloud-scale model study of lightning-generated NOx in an individual thunderstorm during STERAO-A",2000,"10.1029/2000JD900033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-16644379828&doi=10.1029%2f2000JD900033&partnerID=40&md5=ef35b33612aeb2c44d4526bddff4fefb","Understanding lightning NOx (NO + NO2) production on the cloud scale is key for developing better parameterizations of lightning NOx for use in regional and global chemical transport models. This paper attempts to further the understanding of lightning NOx production on the cloud scale using a cloud model simulation of an observed thunderstorm. Objectives are (1) to infer from the model simulations and in situ measurements the relative production rates of NOx by cloud-to-ground (CG) and intracloud (IC) lightning for the storm; (2) to assess the relative contributions in the storm anvil of convective transport of NOx from the boundary layer and NOx production by lightning; and (3) to simulate the effects of the lightning-generated NOx on subsequent photochemical ozone production. We use a two-dimensional cloud model that includes a parameterized source of lightning-generated NOx to study the production and advection of NOx associated with a developing northeast Colorado thunderstorm observed on July 12, 1996, during the Stratosphere-Troposphere Experiment - Radiation, Aerosols, Ozone (STERAO-A) field campaign. Model results are compared with the sum of NO measurements taken by aircraft and photostationary state estimates of NO2 in and around the anvil of the thunderstorm. The results show that IC lightning was the dominant source of NOx in this thunderstorm. We estimate from our simulations that the NOx production per CG flash (PCG) was of the order of 200 to 500 mol flash-1. NOx production per IC flash (PIC) appeared to be half or more of that for a CG flash, a higher ratio of PIC/PCG than is commonly assumed. The results also indicate that the majority of NOx (greater than 80%) in the anvil region of this storm resulted from lightning as opposed to transport from the boundary layer. The effect of the lightning NOx on subsequent photochemical ozone production was assessed using a column chemical model initialized with values of NOx, O3, and hydrocarbons taken from a horizontally averaged vertical profile through the anvil of the simulated storm. The lightning NOx increased simulated ozone production rates by a maximum of over 7 ppbv d-1 in the upper troposphere downwind of this storm. Copyright 2000 by the American Geophysical Union."
"9436442500;37114281100;24491934500;6602758119;7005956394;","Electrical mobility spectrometer using a diethylene glycol condensation particle counter for measurement of aerosol size distributions down to 1 nm",2011,"10.1080/02786826.2010.547538","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78751626997&doi=10.1080%2f02786826.2010.547538&partnerID=40&md5=ec831e82352535a18bd05a95524ab1c3","We report a new scanning mobility particle spectrometer (SMPS) for measuring number size distributions of particles down to ∼1 nm mobility diameter. This SMPS includes an aerosol charger, a TSI 3085 nano differential mobility analyzer (nanoDMA), an ultrafine condensation particle counter (UCPC) using diethylene glycol (DEG) as the working fluid, and a conventional butanol CPC (the ""booster"") to detect the small droplets leaving the DEG UCPC. The response of the DEG UCPC to negatively charged sodium chloride particles with mobility diameters ranging from 1-6 nm was measured. The sensitivity of the DEG UCPC to particle composition was also studied by comparing its response to positively charged 1.47 and 1.70 nm tetra-alkyl ammonium ions, sodium chloride, and silver particles. A high resolution differential mobility analyzer was used to generate the test particles. These results show that the response of this UCPC to sub-2 nm particles is sensitive to particle composition. The applicability of the new SMPS for atmospheric measurement was demonstrated during the Nucleation and Cloud Condensation Nuclei (NCCN) field campaign (Atlanta, Georgia, summer 2009). We operated the instrument at saturator and condenser temperatures that allowed the efficient detection of sodium chloride particles but not of air ions having the same mobility. We found that particles as small as 1 nm were detected during nucleation events but not at other times. Factors affecting size distribution measurements, including aerosol charging in the 1-10 nm size range, are discussed. For the charger used in this study, bipolar charging was found to be more effective for sub-2 nm particles than unipolar charging. No ion induced nucleation inside the charger was observed during the NCCN campaign. Copyright © Taylor & Francis Group, LLC."
"24390246100;21734501300;7006185793;7003385765;7202920419;","Characteristics of cloud-to-ground lightning in warm-season thunderstorms in the Central Great Plains",2009,"10.1016/j.atmosres.2008.08.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-58149302884&doi=10.1016%2fj.atmosres.2008.08.011&partnerID=40&md5=8dc7a19229d3b100290f7c4d765b0028","In July 2005, a field campaign was conducted in the Central Great Plains to obtain 60-field/s video imagery of lightning in correlation with reports from the U.S. National Lightning Detection Network (NLDN) and broadband electric field waveforms from the Los Alamos Sferic Array (LASA). A total of 342 GPS time-stamped cloud-to-ground (CG) flashes were recorded in 17 different sessions, and 311 (91%) of these were correlated with reports from the NLDN. Only 6 of the 17 recording sessions were dominated by flashes that lowered negative charge to ground, and 11 were dominated by positive CG flashes. A total of 103 flashes recorded on video were correlated with at least one NLDN report of negative CG strokes, 204 video flashes were correlated with one or two positive stroke reports, and 4 had bipolar reports. In this paper, we will give distributions of the estimated peak current, Ip, as reported by the NLDN, of negative and positive first strokes that were recorded on video, the multiplicity of strokes that were recorded on video, and the number of ground contacts per flash that were resolved on video. 41 (40%) of the negative flashes produced just a single-stroke on video, and 62 (60%) showed two or more strokes. The observed multiplicity of negative flashes averaged 2.83, which becomes about 3.14 after correcting for the finite time-resolution of the video camera. 195 (96%) of the positive flashes produced just a single-stroke on video, and 9 (4%) showed two strokes; therefore, the observed multiplicity of positive flashes averaged 1.04. Five out of 9 (56%) of the positive subsequent strokes re-illuminated a previous channel, and 4 out of 9 (44%) created a new ground contact. Simultaneous video, LASA, and NLDN measurements also allowed us to examine the classification of NLDN reports during 3 single-cell storms (one negative and two positive). Based on the LASA waveforms, a total of 204 out of 376 (54%) NLDN reports of CG strokes were determined to be for cloud pulses. The misclassified negative reports had |Ip| values ranging from 3.8 kA to 29.7 kA, but only 58 (24%) of these had |Ip| &gt; 10 kA, and only one misclassified positive report had Ip &gt; 20 kA. Radar analyses showed that most of the negative and positive CG strokes that were recorded on video were produced within or near the convective cores of storms. The radar imagery also showed that single-cell storms tended to produce one polarity of CG flashes at a time, and that such storms could switch rapidly from negative to positive CG flashes when the reflectivity was near maximum. Multiple-cell storms produced both negative and positive flashes over a broad region, but each polarity tended to cluster near regions of high-reflectivity. © 2008 Elsevier B.V. All rights reserved."
"57209647985;6701378450;7402370453;","Scanning mobility CCN analysis-A method for fast measurements of size-resolved CCN distributions and activation kinetics",2010,"10.1080/02786826.2010.498715","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955599850&doi=10.1080%2f02786826.2010.498715&partnerID=40&md5=01feab7f2b205221d61086bee0f0925e","We present Scanning Mobility CCN Analysis (SMCA) as a novel method for obtaining rapid measurements of size-resolved cloud condensation nuclei (CCN) distributions and activation kinetics. SMCA involves sampling the monodisperse outlet stream of a Differential Mobility Analyzer (DMA) operated in scanning voltage mode concurrently with CCN and condensation particle counters. By applying the same inversion algorithm as used for obtaining size distributions with a scanning mobility particle sizer (SMPS), CCN concentration and activated droplet size are obtained as a function of mobility size over the timescale of an SMPS scan (typically 60-120 s). Methods to account for multiple charging, particle non-sphericity, and limited counting statistics are presented. SMCA is demonstrated using commercial SMPS and CFSTGC instruments with the manufacturer-provided control software. The method is evaluated for activation of both laboratory aerosol and ambient aerosol obtained during the 2004 NEAQS-ITCT2k4 field campaign. It is shown that SMCA reproduces the results obtained with a DMA operating in voltage ""stepping"" mode. Copyright © American Association for Aerosol Research."
"35264611800;6602097544;7101846027;6508259172;7006572336;57196499374;","The Marine Stratus/Stratocumulus Experiment (MASE): Aerosol-cloud relationships in marine stratocumulus",2007,"10.1029/2006JD007985","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547594524&doi=10.1029%2f2006JD007985&partnerID=40&md5=91421817e133dd92aa91d96537b46850","The Marine Stratus/Stratocumulus Experiment (MASE) field campaign was undertaken in July 2005 off the coast of Monterey, California to evaluate aerosol-cloud relationships in the climatically important regime of eastern Pacific marine stratocumulus. Aerosol and cloud properties were measured onboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. One cloud that was clearly impacted by ship emissions as well as the ensemble of clouds observed over the entire mission are analyzed in detail. Results at both the individual and ensemble scales clearly confirm the Twomey effect (first indirect effect of aerosols) and demonstrate drizzle suppression at elevated aerosol number concentration. For the ship track impacted cloud, suppressed drizzle in the track led to a larger cloud liquid water path (LWP) at the same cloud thickness, in accord with the so-called second indirect effect. Ensemble averages over all clouds sampled over the entire 13-flight mission show the opposite effect of aerosol number concentration on LWP, presumably the result of other dynamic influences (e.g., updraft velocity and ambient sounding profile). Individual polluted clouds were found to exhibit a narrower cloud drop spectral width in accord with theoretical prediction (M.-L. Lu and J. H. Seinfeld, Effect of aerosol number concentration on cloud droplet dispersion: A large-eddy simulation study and implications for aerosol indirect forcing, Journal of Geophysical Research, 2006). This field experiment demonstrates both the indirect aerosol effect on ship track perturbed clouds, as well as the subtleties involved in extracting these effects over an ensemble of clouds sampled over a 1-month period. Copyright 2007 by the American Geophysical Union."
"6603439875;7005882490;7005254328;7101846027;","An exploration of aqueous oxalic acid production in the coastal marine atmosphere",2004,"10.1016/j.atmosenv.2004.04.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942748444&doi=10.1016%2fj.atmosenv.2004.04.009&partnerID=40&md5=e92fe7856c7ae753d194d992a44dd58e","Oxalic acid is the most abundant dicarboxylic acid found in the troposphere, yet there is still no scientific consensus concerning its origins or formation process. Recent studies have suggested mechanisms for its formation in cloud water from gaseous precursors. Comparison of the characteristics of oxalic acid and nss sulfate, a chemical with a known in-cloud formation pathway, provides some support for an aqueous formation mechanism for oxalic acid. Analysis of the filters collected from the CIRPAS Twin Otter aircraft during CARMA I, a field campaign designed to study the marine stratocumulus off the coast of Monterey, CA, by a five stage Micro-Orifice Impactor (MOI) revealed a peak in the concentration distribution at a diameter of 0.26-0.44μm, similar to the size distribution found for nss sulfate and corresponding to the droplet mode in the aerosol size distribution. An air-equivalent average of 2.03±0.47μgm-3 (standard error) of sulfate was observed in the collected marine cloud water, in excess to below-cloud concentrations by 1.16μgm-3 on average. This suggests in-cloud production similar in concentration to previous field campaigns in coastal marine atmospheres. Oxalate was observed in the clouds at air-equivalent concentrations of 0.21±0.04μgm-3, in excess to below-cloud concentrations by 0.14μgm-3 and suggesting an in-cloud production as well. The tentative identification in cloud water of one of the intermediate species in the aqueous oxalate production mechanism lends further support to an in-cloud oxalate source. © 2004 Elsevier Ltd. All rights reserved."
"7004056721;7004346367;6701845055;35291021400;7006383649;55718857500;23161713000;","Optical-chemical-microphysical relationships and closure studies for mixed carbonaceous aerosols observed at Jeju Island; 3-laser photoacoustic spectrometer, particle sizing, and filter analysis",2010,"10.5194/acp-10-10387-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78149344620&doi=10.5194%2facp-10-10387-2010&partnerID=40&md5=2c89613071af9455ee83e2971a18da34","Transport of aerosols in pollution plumes from the mainland Asian continent was observed in situ at Jeju, South Korea during the Cheju Asian Brown Cloud Plume-Asian Monsoon Experiment (CAPMEX) field campaign throughout August and September 2008 using a 3-laser photoacoustic spectrometer (PASS-3), chemical filter analysis, and size distributions. The PASS-3 directly measures the effects of morphology (e.g. coatings) on light absorption that traditional filter-based instruments are unable to address. Transport of mixed sulfate, carbonaceous, and nitrate aerosols from various Asian pollution plumes to Jeju accounted for 74% of the deployment days, showing large variations in their measured chemical and optical properties. Analysis of eight distinct episodes, spanning wide ranges of chemical composition, optical properties, and source regions, reveals that episodes with higher organic carbon (OC)/sulfate (SO 2-4 ) and nitrate (NO-3 )/SO2- 4 composition ratios exhibit lower single scatter albedo at shorter wavelengths (!405). We infer complex refractive indices (n-ik) as a function of wavelength for the high, intermediate, and low OC/SO2-4 pollution episodes by using the observed particle size distributions and the measured optical properties. The smallest mean particle diameter corresponds to the high OC/SO2-4 aerosol episode. The imaginary part of the refractive index (k) is greater for the high OC/SO2- 4 episode at all wavelengths. A distinct, sharp increase in k at short wavelength implies enhanced light absorption by OC, which accounts for 50% of the light absorption at 405 nm, in the high OC/SO2-4 episode. Idealized analysis indicates increased absorption at 781 nm by factors greater than 3 relative to denuded black carbon in the laboratory. We hypothesize that coatings of black carbon cores are the mechanism of this enhancement. This implies that climate warming and atmospheric heating rates from black carbon particles can be significantly larger than have been estimated previously. The results of this study demonstrate ways in which atmospheric processing and mixing can amplify particle light absorption for carbonaceous aerosol, significantly at short wavelength, underscoring the need to understand and predict chemical composition effects on optical properties to accurately estimate the climate radiative forcing by mixed carbonaceous aerosols. © 2010 Author(s)."
"57198616562;7102643810;6506385754;57191675258;7102965584;6603834291;57191662809;57193132723;14019348000;57191645523;8658386900;7005729142;7003283811;57191664971;7202119915;7006575272;57191646955;57191666155;7005461477;57191657948;57191651396;57191669813;7102190308;7401936984;7003926380;","The midlatitude continental convective clouds experiment (MC3E)",2016,"10.1175/BAMS-D-14-00228.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992345002&doi=10.1175%2fBAMS-D-14-00228.1&partnerID=40&md5=c6b29faa68132d1b2be290174dee1325","The Midlatitude Continental Convective Clouds Experiment (MC3E) is a field campaign aimed at acquiring a more complete understanding of the physical processes driving the life cycle of mid-latitude convective clouds. MC3E took place from 22 April through 6 June 2011, and was focused at and around the DOE ARM Southern Great Plains (SGP) Central Facility (CF) in north-central Oklahoma, where an extensive array of both airborne and ground-based instrumentation was deployed. At the top of the sampling domain, the NASA ER-2 aircraft functioned as a GPM core-satellite sampling simulator. It carried the dual-frequency, dual-beam nadir-pointing Doppler, High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), and two multifrequency passive microwave radiometers. At the largest scale a radiosonde network was deployed to quantify the temperature, humidity, and wind properties of the environment surrounding the ARM SGP CF. MC3E staff launched 1,348 coordinated weather balloons from six sites at a frequency of four times per day under nonconvective conditions in order to partially sample the diurnal cycle. Surrounding the SGP CF was a dense network of 18 autonomous Particle Size and Velocity (PARSIVEL) disdrometers. The coordinated efforts resulted in a very successful MC3E field campaign whose datasets will be the focus of scientific research for many years."
"7005729142;7202057166;6506385754;7004198777;","Improved representation of ice particle masses based on observations in natural clouds",2010,"10.1175/2010JAS3507.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77958581331&doi=10.1175%2f2010JAS3507.1&partnerID=40&md5=9e386a1c66812bd6d7a2c1885be9f6be","The mass-dimensional relationship put forth by Brown and Francis has been widely used for developing parameterizations for representing ice cloud microphysical properties. This relationship forms the cornerstone for past and forthcoming retrievals of ice cloud properties from ground-based and spaceborne active and passive sensors but has yet to be rigorously evaluated. This study uses data from six field campaigns to evaluate this mass-dimensional relationship in a variety of ice cloud types and temperatures and to account for the deviations observed with temperature and size, based on properties of the ice particle ensembles. Although the Brown and Francis relationship provides a good match to the observations in a mean sense, it fails to capture dependences on temperature and particle size that are a result of the complex microphysical processes operative within most ice cloud layers. Mass-dimensional relationships that provide a better fit to the observations are developed. © 2010 American Meteorological Society."
"37013011200;7102811204;57193072346;35226698000;56278186400;","Integration of optical and synthetic aperture radar imagery for improving crop mapping in northwestern Benin, West Africa",2014,"10.3390/rs6076472","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84904497228&doi=10.3390%2frs6076472&partnerID=40&md5=162edbf080e2a67036387ffd99869a53","Crop mapping in West Africa is challenging, due to the unavailability of adequate satellite images (as a result of excessive cloud cover), small agricultural fields and a heterogeneous landscape. To address this challenge, we integrated high spatial resolution multi-temporal optical (RapidEye) and dual polarized (VV/VH) SAR (TerraSAR-X) data to map crops and crop groups in northwestern Benin using the random forest classification algorithm. The overall goal was to ascertain the contribution of the SAR data to crop mapping in the region. A per-pixel classification result was overlaid with vector field boundaries derived from image segmentation, and a crop type was determined for each field based on the modal class within the field. A per-field accuracy assessment was conducted by comparing the final classification result with reference data derived from a field campaign. Results indicate that the integration of RapidEye and TerraSAR-X data improved classification accuracy by 10%-15% over the use of RapidEye only. The VV polarization was found to better discriminate crop types than the VH polarization. The research has shown that if optical and SAR data are available for the whole cropping season, classification accuracies of up to 75% are achievable. & copy ; 2014 by the authors."
"36622957800;18438062100;10042680800;6505876262;35620030700;57205497099;57200319386;","A high spatial resolution retrieval of NO2 column densities from OMI: Method and evaluation",2011,"10.5194/acp-11-8543-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052002463&doi=10.5194%2facp-11-8543-2011&partnerID=40&md5=f1497221e03e9d6bffe01284c816048c","We present a new retrieval of tropospheric NO2 vertical column density from the Ozone Monitoring Instrument (OMI) based on high spatial and temporal resolution terrain and profile inputs. We compare our NO2 product, the Berkeley High-Resolution (BEHR) product, with operational retrievals and find that the operational retrievals are biased high (30 %) over remote areas and biased low (8 %) over urban regions. Additionally, we find non-negligible impacts on the retrieved NO2 column for terrain pressure (±20 %), albedo (±40 %), and NO2 vertical profile (ĝ̂'75 %ĝ€""+10 %). We validate the operational and BEHR products using boundary layer aircraft observations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS-CA) field campaign which occurred in June 2008 in California. Results indicate that columns derived using our boundary layer extrapolation method show good agreement with satellite observations (Ri&gt;2 Combining double low line 0.65-0.83; &lt;iNCombining double low line 68) and provide a more robust validation of satellite-observed NO2 column than those determined using full vertical spirals (iR&lt;2 Combining double low line 0.26; iN Combining double low line 5) as in previous work. Agreement between aircraft observations and the BEHR product (iR2 Combining double low line 0.83) is better than agreement with the operational products (iR2 Combining double low line 0.65-0.72). We also show that agreement between satellite and aircraft observations can be further improved (e.g. BEHR: iR2 Combining double low line 0.91) using cloud information from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument instead of the OMI cloud product. These results indicate that much of the variance in the operational products can be attributed to coarse resolution terrain pressure, albedo, and profile parameters implemented in the retrievals. © 2011 Author(s)."
"55663817800;","Effects of ice particles shattering on the 2D-S probe",2011,"10.5194/amt-4-1361-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052824968&doi=10.5194%2famt-4-1361-2011&partnerID=40&md5=ac659d283c84148878d857c094c38e37","Recently, considerable attention has been focused on the issue of large ice particles shattering on the inlets and tips of cloud particle probes, which produces copious ice particles that can be mistakenly measured as real ice particles. Currently two approaches are being used to mitigate the problem: (1) Based on recent high-speed video in icing tunnels, probe tips have been designed that reduce the number of shattered particles that reach the probe sample volume, and (2) Post processing techniques such as image processing and using the arrival time of each individual particle. This paper focuses on exposing suspected errors in measurements of ice particle size distributions due to shattering, and evaluation of the two techniques used to reduce the errors. Data from 2D-S probes constitute the primary source of the investigation, however, when available comparisons with 2D-C and CIP measurements are also included. Korolev et al. (2010b) report results from a recent field campaign (AIIE) and conclude that modified probe tips are more effective than an arrival time algorithm when applied to 2D-C and CIP measurements. Analysis of 2D-S data from the AIIE and SPARTICUS field campaigns shows that modified probe tips significantly reduce the number of shattered particles, but that a particle arrival time algorithm is more effective than the probe tips designed to reduce shattering. A large dataset of 2D-S measurements with and without modified probe tips was not available from the AIEE and SPARTICUS field campaigns. Instead, measurements in regions with large ice particles are presented to show that shattering on the 2D-S with modified probe tips produces large quantities of small particles that are likely produced by shattering. Also, when an arrival time algorithm is applied to the 2D-S data, the results show that it is more effective than the modified probe tips in reducing the number of small (shattered) particles. Recent results from SPARTICUS and MACPEX show that 2D-S ice particle concentration measurements are more consistent with physical arguments and numerical simulations than measurements with older cloud probes from previous field campaigns. The analysis techniques in this paper can also be used to estimate an upper bound for the effects of shattering. For example, the additional spurious concentration of small ice particles can be measured as a function of the mass concentration of large ice particles. The analysis provides estimates of upper bounds on the concentration of natural ice, and on the remaining concentration of shattered ice particles after application of the post-processing techniques. However, a comprehensive investigation of shattering is required to quantify effects that arise from the multiple degrees of freedom associated with this process, including different cloud environments, probe geometries, airspeed, angle of attack, particle size and type. © 2011 Author(s)."
"7103293742;7006728825;7402579146;56087850300;14045744500;7102875670;7006861480;7003923355;6508333712;14044750400;7004239300;23491240100;6507690692;7201572145;57201806565;7103010648;23492161700;57196965551;24437137100;7102425008;13007466900;7401584990;23491773400;6604053026;7003510880;22953390300;57219982231;7003696133;23492293800;14826864700;7006617518;36941730100;23493250700;55707134700;9536598800;7201769764;6701732679;7004860305;7101691582;57203492395;16444713000;6506355037;23486614500;7202129754;35559590900;57207295412;8716974000;7102132806;23494102200;7004066230;8353996200;7402883211;35326039600;","The convective storm initiation project",2007,"10.1175/BAMS-88-12-1939","https://www.scopus.com/inward/record.uri?eid=2-s2.0-39049127121&doi=10.1175%2fBAMS-88-12-1939&partnerID=40&md5=09b4dd96a26f90f9c1eddbbf12855b02","The Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is to compare the results of the very high resolution Met Office weather forecasting model with detailed observations of the early stages of convective clouds and to use the newly gained understanding to improve the predictions of the model. A large array of ground-based instruments plus two instrumented aircraft, from the U.K. National Centre for Atmospheric Science (NCAS) and the German Institute for Meteorology and Climate Research (IMK), Karlsruhe, were deployed in southern England, over an area centered on the meteorological radars at Chilbolton, during the summers of 2004 and 2005. In addition to a variety of ground-based remote-sensing instruments, numerous rawin-sondes were released at one- to two-hourly intervals from six closely spaced sites. The Met Office weather radar network and Meteosat satellite imagery were used to provide context for the observations made by the instruments deployed during CSIP. This article presents an overview of the CSIP field campaign and examples from CSIP of the types of convective initiation phenomena that are typical in the United Kingdom. It shows the way in which certain kinds of observational data are able to reveal these phenomena and gives an explanation of how the analyses of data from the field campaign will be used in the development of an improved very high resolution NWP model for operational use. © 2008 American Meteorological Society Privacy Policy and Disclaimer."
"6602914876;35998927000;7102862273;35593636200;7102655202;56490302800;56187256200;55684491100;","Aircraft observations of the upper tropospheric fine particle aerosol in the Northern and Southern Hemispheres at midlatitudes",2003,"10.1029/2002gl016458","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042784651&doi=10.1029%2f2002gl016458&partnerID=40&md5=cbe8b7e8daeaae46233221ac63059f9c","As part of the project INCA (Interhemispheric Differences in Cirrus Properties from Anthropogenic Emissions) two aircraft field campaigns have been performed to study aerosol and cirrus cloud properties of the upper troposphere (UT) in the midlatitudes of the southern hemisphere (SH) and the northern hemisphere (NH). This paper focuses on the measurements of UT number concentrations and tropospheric vertical profiles of volatile and refractory Aitken as well as total accumulation mode particles. The results are discussed with respect to interhemispheric differences. Aerosol number concentrations in the NH are more variable and typically a factor of 2-3 higher. The SH data considerably extend the few existing UT in situ aerosol measurements in the SH midlatitudes."
"26643615000;35494005000;7410041005;7201677208;","Evaluation of several A-Train ice cloud retrieval products with in situ measurements collected during the SPARTICUS campaign",2013,"10.1175/JAMC-D-12-054.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876807648&doi=10.1175%2fJAMC-D-12-054.1&partnerID=40&md5=469f0ee1eae69a8e5c7876ee30a74406","In this study several ice cloud retrieval products that utilize active and passive A-Train measurements are evaluated using in situ data collected during the Small Particles in Cirrus (SPARTICUS) field campaign. The retrieval datasets include ice water content (IWC), effective radius re, and visible extinction s from CloudSat level-2C icecloud property product (2C-ICE), CloudSat level-2B radar-visible optical depth cloud water content product (2B-CWC-RVOD), radar-slidar(DARDAR), and s from Cloud-Aerosol Lidar and Infrared Pathfinder SatelliteObservations (CALIPSO). When the discrepancies between the radar reflectivity Ze derived from 2D stereo probe (2D-S) in situ measurementsand Ze measured by the CloudSat radar are less than 10 dBZe, the flight mean ratios of the retrieved IWC to the IWC estimated from in situdata are 1.12, 1.59, and 1.02, respectively for 2C-ICE, DARDAR, and 2B-CWC-RVOD. For re, the flight mean ratios are 1.05, 1.18, and 1.61,respectively. For s, the flight mean ratios for 2C-ICE, DARDAR, and CALIPSO are 1.03, 1.42, and 0.97, respectively. The CloudSat 2C-ICE andDARDAR retrieval products are typically in close agreement. However, the use of parameterized radar signals in ice cloud volumes that arebelow the detection threshold of the CloudSat radar in the 2C-ICE algorithm provides an extra constraint that leads to slightly better agreement with in situ data. The differences in assumed mass-size and area-size relations between CloudSat 2C-ICE and DARDAR also contribute tosome subtle difference between the datasets: re from the 2B-CWC-RVOD dataset is biased more than the other retrieval products and in situ measurements by about 40%. A slight low (negative) bias in CALIPSO σ may be due to 5-km averaging in situations in which the cirrus layers have significant horizontal gradients in σ. © 2013 American Meteorological Society."
"7006497723;7005069415;7005020604;35552141500;7006434689;7004923073;","The Jungfraujoch high-alpine research station (3454 m) as a background clean continental site for the measurement of aerosol parameters",1998,"10.1029/97JD03123","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032571178&doi=10.1029%2f97JD03123&partnerID=40&md5=d04b190a2e6c68e096168a2a8a333478","The first annual data set of climatically important aerosol parameters, measured at the Jungfraujoch (JFJ) high-alpine research station (3454 m, Switzerland) from an ongoing field campaign since July 1995, is presented. Analysis of diurnal variations in continuous measurements of the total and backward hemispheric scattering coefficients (8sSP, 8sBSP), the absorption coefficient (8sAP, from aethalometer data), condensation nuclei (CN) concentration, and epiphaniometer signal (related to surface area (S) concentration) established the diurnal period 0300 - 0900 as being representative of the free tropospheric background aerosol. The annual data set was then edited to omit (1) the period 0900 -0300 (i.e., 18 hours), taken to represent possible planetary boundary layer influenced conditions adn (2) in-cloud conditions using a cloud liquid-water monitor. The seasonal aerosol cycle exhibited a July maximum and a December minimum in most aerosol parameters. Typical monthly median values for the free troposphere exhibit the following seasonal maxima and minima, respectively: 8sSP (550 nm) 9a 16.1 and 0.43 x 10-6 m-1, 8sBSP (550 nm) 9a 2.10 and 0.09 x 10-6 m-1, 8sAP (550 nm) 9a 10.4 and 0.76 x 10-7 m-1 (9A 104 and 7.6 ng m-3 black carbon), CN concentrations 9a 670 and 280 cm-3, and epiphaniometer signal 9a 9.26 and 0.67 counts s-1 (S concentration 9A 24.1 and 1.7 8m m2 cm-3). Aerosol parameters were found to be comparable in magnitude to other NOAA baseline and regional stations and suggest that a clean continental designation for the JFJ site is applicable, when removing the planetary boundary layer influenced period."
"57203423392;6701803760;","Aerosol climatology for the planetary boundary layer derived from regular lidar measurements",2002,"10.1016/S0169-8095(02)00043-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036672764&doi=10.1016%2fS0169-8095%2802%2900043-1&partnerID=40&md5=9f180065acf169eeb4916d61452c378a","Regular aerosol extinction and backscatter measurements using a UV Raman Lidar have been performed for almost 3 years in Hamburg in the frame of the German Lidar Network. A set of 92 aerosol extinction and 164 aerosol backscatter profiles has been used for statistical investigations. Mean values and variances of the aerosol extinction and backscatter in the boundary layer have been calculated. Large fluctuations during the whole year have been found. The measured aerosol extinction over Hamburg shows a seasonal cycle with highest values in early fall and a second less prominent peak in spring. An analysis of the data using back trajectories showed a dependence of the aerosol extinction on the origin of the air mass. The residence time of the air mass over industrialized areas was found to be an important parameter for the measured aerosol extinction at Hamburg. However, only a small part of the total variability could be explained by the air mass origin. For 75 cases of aerosol extinction measurements under cloud-free conditions, the aerosol backscatter profile and therefore, the lidar ratio as a function of altitude could be determined. Winter measurements of the lidar ratio are often close to model results for maritime aerosol, the summer measurements are close to the model results for urban or continental aerosols. The high quality of the data has been proven by intercomparisons with other lidar systems and with star photometer measurements of the aerosol optical depth during the Lindenberg Aerosol Characterization Experiment (LACE'98) field campaign. © 2002 Elsevier Science B.V. All rights reserved."
"7005035762;6602137800;7102805852;24722339600;7003899504;6505928063;7003334425;","Smoke and clouds above the southeast Atlantic: Upcoming field campaigns probe absorbing aerosol's impact on climate",2016,"10.1175/BAMS-D-15-00082.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984846944&doi=10.1175%2fBAMS-D-15-00082.1&partnerID=40&md5=883ffb4ed69a97a347c84cf6da6d1392",[No abstract available]
"7405614202;7403931916;7402516470;7201826462;7407116104;7005741798;7101677832;","Inference of ice cloud properties from high spectral resolution infrared observations",2004,"10.1109/TGRS.2003.822752","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442542681&doi=10.1109%2fTGRS.2003.822752&partnerID=40&md5=6a429e1142b6a31f1e7a6dcd83f83d8b","The theoretical basis is explored for inferring the microphysical properties of ice clouds from high spectral resolution infrared (IR) observations. Extensive radiative transfer simulations are carried out to address relevant issues. The single-scattering properties of individual ice crystals are computed from state-of-the-art light scattering computational methods and are subsequently averaged for 30 in situ particle size distributions and for four additional analytical Gamma size distributions. The nonsphericity of ice crystals is shown to have a significant impact on the radiative signatures in the IR spectrum. Furthermore, the errors associated with the use of the Henyey-Greenstein phase function can be larger than 1 K in terms of brightness temperature for large particle effective sizes (∼ 80 μm) at wavenumbers where the scattering of the IR radiation by ice crystals is not negligible. The simulations undertaken in this paper show that the slope of the IR brightness temperature spectrum between 790-960 cm-1 is sensitive to the effective particle size. Furthermore, a strong sensitivity of the IR brightness temperature to cloud optical thickness is noted within the 1050-1250-cm-1 region. Based on these spectral features, a technique is presented for the simultaneous retrieval of the visible optical thickness and effective particle size from high spectral resolution IR data for ice clouds. An error analysis shows that the uncertainties of the retrieved optical thickness and effective particle size have a small range of variation. The error for retrieving particle size in conjunction with an uncertainty of 5 K in cloud temperature, or a surface temperature uncertainty of 2.5 K, is less than 15%. The corresponding errors in the uncertainty of optical thickness are within 5% to 20%, depending on the value of cloud optical thickness. The applicability of the present retrieval technique is demonstrated using airborne high-resolution IR measurements obtained during two field campaigns."
"7003597952;35495958000;","Application of multiscale water and energy balance models on a tallgrass prairie",1994,"10.1029/94WR01499","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028166227&doi=10.1029%2f94WR01499&partnerID=40&md5=3932642d3bcdaa59b4995f374b955651","The models presented in the previous paper (Famiglietti and Wood, this issue) are applied at their appropriate scales for evapotranspiration modeling at the First International Satellite Land Surface Climatology Project Field Experiment (FIFE) site. The local soil‐vegetation‐atmospheric transfer scheme is applied at five flux measurement stations in the northwest quadrant of the FIFE site. Simulations were performed for three of the four FIFE “golden (cloud‐free) days” with good results. The spatially distributed model was applied at the 11.7‐km2 King's Creek catchment, also located in the northwest quadrant of the FIFE site, during FIFE Intensive Field Campaigns (IFCs) 1–4. Simulated catchment average evapotranspiration was compared to an average of observations made at the five aforementioned measurement stations with good results. The macroscale formulation was applied to both the King's Creek catchment and the entire 15‐km FIFE site for evapotranspiration simulations. Macroscale model simulations for King's Creek were nearly identical to the spatially distributed results, implying that at this location and at this scale, the assumptions invoked in the development of the macroscale formulation are reasonable. The macroscale model was also employed to simulate evapotranspiration from the entire 15‐km site for the four golden days. Simulated evapotranspiration rates show reasonably good agreement with the 22‐station average of observations. However, it is suggested that at 15‐km and larger scales, simulation error may arise as a result of the macroscale assumptions of areally averaged atmospheric forcing, vegetation parameters, soil parameters, and the methods by which these data and other flux observations are aggregated. A methodology to combat these problems at larger scales is reviewed. Copyright 1994 by the American Geophysical Union."
"7101752236;7004715270;6602122304;26434854300;7005773698;26028984000;7004198777;","Improvements to an empirical parameterization of heterogeneous ice nucleation and its comparison with observations",2013,"10.1175/JAS-D-12-080.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874988610&doi=10.1175%2fJAS-D-12-080.1&partnerID=40&md5=faa6c640d6c787be71193b28f0bb2ada","A framework for an empirical parameterization (EP) of heterogeneous nucleation of ice crystals by multiple species of aerosol material in clouds was proposed in a 2008 paper by the authors. The present paper reports improvements to specification of a few of its empirical parameters. These include temperatures for onset of freezing, baseline surface areas of aerosol observed in field campaigns over Colorado, and new parameters for properties of black carbon, such as surface hydrophilicity and organic coatings. The EP's third group of ice nucleus (IN) aerosols is redefined as that of primary biological aerosol particles (PBAPs), replacing insoluble organic aerosols. A fourth group of IN is introduced-namely, soluble organic aerosols. The new EP predicts IN concentrations that agree well with aircraft data from selected traverses of shallow wave clouds observed in five flights (1, 3, 4, 6, and 12) of the 2007 Ice in Clouds Experiment-Layer Clouds (ICE-L). Selected traverses were confined to temperatures between about 225° and 229°C in layer cloud without homogeneously nucleated ice from aloft. Some of the wave clouds were affected by carbonaceous aerosols from biomass burning and by dust from dry lakebeds and elsewhere. The EP predicts a trend between number concentrations of heterogeneously nucleated ice crystals and apparent black carbon among the five wave clouds, observed by aircraft in ICE-L. It is predicted in terms of IN activity of black carbon. The EP's predictions are consistent with laboratory and field observations not used in its construction, for black carbon, dust, primary biological aerosols, and soluble organics. The EP's prediction of biological ice nucleation is validated using coincident field observations of PBAP IN and PBAPs in Colorado. © 2013 American Meteorological Society."
"8273707700;7404986193;6507990247;7005461477;","The 29 June 2000 supercell observed during STEPS. Part I: Kinematics and microphysics",2005,"10.1175/JAS3585.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-31144438141&doi=10.1175%2fJAS3585.1&partnerID=40&md5=7997c7b6b1add2587faa5d82baba2e1e","This is a two-part study that addresses the kinematic, microphysical, and electrical aspects of a severe storm that occurred in western Kansas on 29 June 2000 observed during the Severe Thunderstorm Electrification and Precipitation Study (STEPS) field campaign. In this first part, polarimetric and Doppler radar data are used along with a simple particle growth model to examine the evolution of the kinematic and microphysical properties of the storm from its earliest developing phase through its mature and dissipating phases. During its severe stage, the storm exhibited frequent positive cloud-to-ground lightning strikes, very large (∼5 cm) hail, and a tornado. Doppler-derived winds, radar reflectivity, and hydrometeor classifications from the polarimetric data over a nearly 4-h period are presented. It is shown that updraft velocity and vertical vorticity had to reach magnitudes of at least 10 m s-1 and 10-2 s-1 and occupy major portions of the storm before it could produce most of the observed severe storm characteristics. Furthermore, the establishment of cyclonic horizontal flow around the right flank of the updraft core was essential for hail production. Most of the largest hail grew from near millimeter-sized particles that originated in the mid- to upper-level stagnation region that resulted from obstacle-like flow of environmental air around the divergent outflow from the upper part of the updraft. These recycling embryonic particles descended around the right flank of the updraft core and reentered the updraft, intermingling with other smaller particles that had grown from cloud base along the main low-level updraft stream. © 2005 American Meteorological Society."
"15069079300;7004355233;57212444895;57088671100;15069839200;6602983830;7003436166;56219325200;","Validation of the MODIS snow product and cloud mask using student and NWS cooperative station observations in the Lower Great Lakes Region",2006,"10.1016/j.rse.2006.07.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751190731&doi=10.1016%2fj.rse.2006.07.004&partnerID=40&md5=1436d3d83188ef707b67c4af7953618a","NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) snow product (MOD10) creates automated daily, 8-day composite and monthly regional and global snow cover maps. In this study, the MOD10 daily swath imagery (MOD10_L2) and the MODIS cloud mask (MOD35) were validated in the Lower Great Lakes Region, specifically the area to the east of Lake Michigan. Validation of the MOD10_L2 snow product, MOD35 cloud mask and the MOD10_L2 Liberal Cloud Mask was performed using field observations from K-12 student GLOBE (Global Learning and Observations to Benefit the Environment) and SATELLITES (Students And Teachers Evaluating Local Landscapes to Interpret The Earth from Space) programs. Student data consisted of field observations of snow depth, snow water equivalency, cloud type, and total cloud cover. In addition, observations from the National Weather Service (NWS) Cooperative Observing Stations were used. Student observations were taken during field campaigns in the winter of 2001-2002, a winter with very little snow in the Great Lakes region, and the winters of 2000-2001 and 2002-2003, which had significant snow cover. Validation of the MOD10_L2 version 4 snow product with student observations produced an accuracy of 92% while comparison with the NWS stations produced an accuracy of 86%. The higher NWS error appears to come from forested areas. Twenty-five and fifty percent of the errors observed by the students and NWS stations, respectively, occurred when there was only a trace of snow. In addition, 82% of the MODIS cloud masked pixels were identified as either overcast or broken by the student observers while 74% of the pixels the MODIS cloud mask identified as cloudless were identified as clear, isolated or scattered cloud cover by the student observers. The experimental Liberal Cloud Mask eliminated some common errors associated with the MOD35 cloud mask, however, it was found to omit significant cloud cover. © 2006 Elsevier Inc. All rights reserved."
"56522444900;7101790869;14822021400;","Rainfall types in the West African Sudanian zone during the summer monsoon 2002",2006,"10.1175/MWR3182.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747785609&doi=10.1175%2fMWR3182.1&partnerID=40&md5=806f3b19cd16358b70867e27f194de75","Enhanced surface and upper-air observations from the field campaign of the Integrated Approach to the Efficient Management of Scarce Water Resources in West Africa (IMPETUS) project are used to partition rainfall amounts over the West African Sudanian zone during the 2002 summer monsoon season into several characteristic types and subtypes of precipitating systems. The most prominent rainfall subtype was fast-moving, long-lived, and extensive cloud clusters that often developed far upstream over the central Nigerian highlands in the afternoon hours and arrived at the Upper Ouémé Valley (UOV) after midnight. These organized convective systems (advective OCSs, subtype Ia) accounted for 50% of the total rain amount in the UOV catchment in Benin. Subtypes Ia and IIa (i.e., locally developing OCSs) were found to pass by or organize when a highly sheared environment with deep and dry midtropospheric layers was present over the UOV. These systems were most frequent outside the peak of the monsoon season. The second major type of organized convection, termed mesoscale convective systems (subtypes Ib, IIb, and IIIb) in the present study, contributed 26% to the annual UOV precipitation. They occurred in a less-sheared and moister tropospheric environment mainly around the height of the rainy season. A third distinct class of rainfall events occurred during an unusual synoptic situation in which a cyclonic vortex to the north of the UOV led to deep westerly flow. During these periods, the African easterly jet was lacking. The so-called vortex-type rainfalls (subtypes IIIa, IIIb, and IIIc) contributed about 9% to the annual rainfall totals. © 2006 American Meteorological Society."
"14028409200;23991450700;7201735461;57203616353;57204371663;","Effects of corn on C- and L-band radar backscatter: A correction method for soil moisture retrieval",2010,"10.1016/j.rse.2010.05.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956175490&doi=10.1016%2fj.rse.2010.05.017&partnerID=40&md5=8b527ced8a22c65af39995e37206df44","This paper discusses the effects of vegetation on C- (4.75GHz) and L- (1.6GHz) band backscattering (σo) measured throughout a growth cycle at incidence angles of 15, 35 and 55°. The utilized σo data set was collected by a truck mounted scatterometer over a corn field and is supported by a comprehensive set of ground measurements, including soil moisture and vegetation biomass. Comparison of σo measurement against simulations by the Integral Equation Method (IEM) surface scattering model (Fung et al., 1992) shows that the σo measurements are dominated either by an attenuated soil return or by scattering from vegetation depending on the antenna configuration and growth stage. Further, the measured σo is found to be sensitive to soil moisture even at peak biomass and large incidence angles, which is attributed to scattering along the soil-vegetation pathway.For the simulation of C-band σo and the retrieval of soil moisture two methods have been applied, which are the semi-empirical water cloud model (Attema &amp; Ulaby, 1978) and a novel method. This alternative method uses the empirical relationships between the vegetation water content (W) and the ratio of the bare soil and the measured σo to correct for vegetation. It is found that this alternative method is superior in reproducing the measured σo as well as retrieving soil moisture. The highest retrieval accuracies are obtained at a 35° incidence angle leading to RMSD's of 0.044 and 0.037m3m-3 for the HH and VV-polarization, respectively. In addition, the sensitivity of these soil moisture retrievals to W and surface roughness parameter uncertainties is investigated. © 2010."
"35305673400;6701404949;","Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx-Part 1: Mean structure and diurnal cycle",2010,"10.5194/acp-10-4491-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952505600&doi=10.5194%2facp-10-4491-2010&partnerID=40&md5=1d7ab01266eefe9b953befb5396e9001","Atmospheric subsidence over the subtropical southeast Pacific (SEP) leads to a low-level anticyclonic circulation, a cool sea surface and a cloud-topped marine boundary layer (MBL). Observations in this region from a major field campaign during October and November 2008, the VOCALS Regional Experiment, provide ample data to characterize the lower atmospheric features over the SEP. The observations are also useful to test the ability of an area-limited, high-resolution atmospheric model to simulate the SEP conditions. Observations and model-results (where appropriate) improve the characterization of the mean state (Part 1) and variability (Part 2) of the lower troposphere including circulation, MBL characteristics and the upsidence wave. Along 20° S the MBL is generally deeper offshore (1600 m at 85° W) but there is also considerable variability. MBL depth and variability decrease towards the coast and maximum inversion strength is detected between 74-76° W. Weather Research and Forecasting (WRF) simulations underestimate MBL height the most near the coast but improve offshore. Southeasterly trades prevail within the MBL although the wind speed decreases toward the coast. Above the MBL along the coast of Chile, flow is northerly, has a maximum at 3 km, and extends westward to ∼74° W, apparently due to the mechanical blocking exerted by the Andes upon the westerly flow aloft. Mean MBL features along northern Chile (18-25° S) are remarkably similar (e.g., MBL depth just below 1 km) in spite of different SST. Observed diurnal cycles of the temperature at the coast and further offshore exhibit a number of conspicuous features that are consistent with the southwestward propagation of an upsidence wave initiated during late evening along the south Peru coast. Furthermore, the passage of the vertical motion results in either constructive or deconstructive interference with the radiatively-forced diurnal cycle of MBL depth. Interference is clearly seen in the soundings at Iquique which are driven by a strong upsidence wave contrary to the radiation-driven cycle, leading to a diurnal cycle opposite of the other sites. Because WRF simulations have a lower MBL height, the speed of the simulated gravity wave is slower than observations and accounts for most of the discrepancy between observed and simulated phase speeds. © 2010 Author(s)."
"7402838215;55469200300;55801231800;6506848120;15726759700;57188729343;36106191000;6506126751;35595682100;7201951829;7005960178;7004740995;57204252724;7005941217;54393349200;7003763119;","A microphysics guide to cirrus clouds-Part 1: Cirrus types",2016,"10.5194/acp-16-3463-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962486253&doi=10.5194%2facp-16-3463-2016&partnerID=40&md5=50f013840ffd8985b1db03cf5badefb5","The microphysical and radiative properties of cirrus clouds continue to be beyond understanding and thus still represent one of the largest uncertainties in the prediction of the Earth's climate (IPCC, 2013). Our study aims to provide a guide to cirrus microphysics, which is compiled from an extensive set of model simulations, covering the broad range of atmospheric conditions for cirrus formation and evolution. The model results are portrayed in the same parameter space as field measurements, i.e., in the Ice Water Content-Temperature (IWC-T) parameter space. We validate this cirrus analysis approach by evaluating cirrus data sets from 17 aircraft campaigns, conducted in the last 15 years, spending about 94 h in cirrus over Europe, Australia, Brazil as well as South and North America. Altogether, the approach of this study is to track cirrus IWC development with temperature by means of model simulations, compare with observations and then assign, to a certain degree, cirrus microphysics to the observations. Indeed, the field observations show characteristics expected from the simulated Cirrus Guide. For example, high (low) IWCs are found together with high (low) ice crystal concentrations <i>N</i>ice. <br><br> An important finding from our study is the classification of two types of cirrus with differing formation mechanisms and microphysical properties: the first cirrus type forms directly as ice (in situ origin cirrus) and splits in two subclasses, depending on the prevailing strength of the updraft: in slow updrafts these cirrus are rather thin with lower IWCs, while in fast updrafts thicker cirrus with higher IWCs can form. The second type consists predominantly of thick cirrus originating from mixed phase clouds (i.e., via freezing of liquid droplets-liquid origin cirrus), which are completely glaciated while lifting to the cirrus formation temperature region (&lt; 235 K). In the European field campaigns, slow updraft in situ origin cirrus occur frequently in low-and high-pressure systems, while fast updraft in situ cirrus appear in conjunction with jet streams or gravity waves. Also, liquid origin cirrus mostly related to warm conveyor belts are found. In the US and tropical campaigns, thick liquid origin cirrus which are formed in large convective systems are detected more frequently. © 2016 Author(s)."
"6701823396;6602195544;6602426672;6701905330;24472110700;7003875148;6508213402;55765742100;9248887100;7402740637;6701750289;53874648600;7006238452;6603689866;36458171200;7003772482;","Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: A review",2014,"10.5194/acp-14-9403-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84919616512&doi=10.5194%2facp-14-9403-2014&partnerID=40&md5=7a3990a5c3194304ad94d57dab1a7e5d","The Arctic climate system includes numerous highly interactive small-scale physical processes in the atmosphere, sea ice, and ocean. During and since the International Polar Year 2007-2009, significant advances have been made in understanding these processes. Here, these recent advances are reviewed, synthesized, and discussed. In atmospheric physics, the primary advances have been in cloud physics, radiative transfer, mesoscale cyclones, coastal, and fjordic processes as well as in boundary layer processes and surface fluxes. In sea ice and its snow cover, advances have been made in understanding of the surface albedo and its relationships with snow properties, the internal structure of sea ice, the heat and salt transfer in ice, the formation of superimposed ice and snow ice, and the small-scale dynamics of sea ice. For the ocean, significant advances have been related to exchange processes at the ice-ocean interface, diapycnal mixing, double-diffusive convection, tidal currents and diurnal resonance. Despite this recent progress, some of these small-scale physical processes are still not sufficiently understood: these include wave-turbulence interactions in the atmosphere and ocean, the exchange of heat and salt at the ice-ocean interface, and the mechanical weakening of sea ice. Many other processes are reasonably well understood as stand-alone processes but the challenge is to understand their interactions with and impacts and feedbacks on other processes. Uncertainty in the parameterization of small-scale processes continues to be among the greatest challenges facing climate modelling, particularly in high latitudes. Further improvements in parameterization require new year-round field campaigns on the Arctic sea ice, closely combined with satellite remote sensing studies and numerical model experiments. © Author(s) 2014. CC Attribution 3.0 License."
"7004369046;56120916000;7407016988;7103201242;7102609908;7402480218;23502460300;6508268711;55964684700;35419560700;7404195755;7403053395;6506961436;","Quality-controlled upper-air sounding dataset for DYNAMO/CINDY/AMIE: Development and corrections",2014,"10.1175/JTECH-D-13-00165.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898899952&doi=10.1175%2fJTECH-D-13-00165.1&partnerID=40&md5=1fee28a4298a82ef0b2a9cfbf0117187","The upper-air sounding network for Dynamics of the Madden-Julian Oscillation (DYNAMO) has provided an unprecedented set of observations for studying the MJO over the Indian Ocean, where coupling of this oscillation with deep convection first occurs. With 72 rawinsonde sites and dropsonde data from 13 aircraft missions, the sounding network covers the tropics from eastern Africa to the western Pacific. In total nearly 26 000 soundings were collected from this network during the experiment's 6-month extended observing period (from October 2011 to March 2012). Slightly more than half of the soundings, collected from 33 sites, are at high vertical resolution. Rigorous post-field phase processing of the sonde data included several levels of quality checks and a variety of corrections that address a number of issues (e.g., daytime dry bias, baseline surface data errors, ship deck heating effects, and artificial dry spikes in slow-ascent soundings). Because of the importance of an accurate description of the moisture field in meeting the scientific goals of the experiment, particular attention is given to humidity correction and its validation. The humidity corrections, though small relative to some previous field campaigns, produced high-fidelity moisture analyses in which sonde precipitable water compared well with independent estimates. An assessment of operational model moisture analyses using corrected sonde data shows an overall good agreement with the exception at upper levels, where model moisture and clouds are more abundant than the sonde data would indicate. © 2014 American Meteorological Society."
"36867650000;7006432091;","The cloud population and onset of the Madden-Julian Oscillation over the Indian Ocean during DYNAMO-AMIE",2013,"10.1002/2013JD020421","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889847973&doi=10.1002%2f2013JD020421&partnerID=40&md5=22b255189c4e25e3c5b7b65d0d12e471","Variability of the cloud population in the central equatorial Indian Ocean was observed in the context of the Madden-Julian Oscillation (MJO) during the Dynamics of the Madden-Julian Oscillation (DYNAMO) and Atmospheric Radiation Measurement Madden-Julian Investigation Experiment (AMIE) field campaigns. Radar observations from the polarimetric S-band radar on Addu Atoll in the Maldives characterize the types of convective and stratiform radar echoes and the heights their 20 dBZ contours reach. To gain insight into the relationship between clouds and humidification of the troposphere leading up to and during an active MJO event, the work relates variability of the observed precipitation structure to that of tropospheric humidity and upper level zonal wind. The variability in stratiform precipitation areas dominates variability in the nature of precipitating convection associated with the MJO. Areal coverage of precipitating radar echo, convective echo top height, and tropospheric humidity above 850 hPa rapidly increase over ∼3-7 days near MJO onset. This rate of increase is substantially faster than the 10-20 days needed for buildup of moisture prior to MJO onset as hypothesized by the ""discharge- recharge"" hypothesis. Convective echoes become more common during the days prior to MJO onset, and the increased convection occurs before low-tropospheric moistening. The upper troposphere rapidly moistens as the first widespread stratiform region passes over an area. Thus, clouds likely play a role in tropospheric humidification. Whether increased low-tropospheric humidity causes vertical growth of convection has not yet been determined. Key Points MJO onset characterized by sharp increase in stratiform precipitation Humidity and convective depth also increase over 3-7 days at MJO onset Convection contributes to tropospheric moistening prior to MJO onset ©2013. American Geophysical Union. All Rights Reserved."
"6508182670;6505919411;7403401100;6508259172;7101846027;7006572336;57196499374;","Toward aerosol/cloud condensation nuclei (CCN) closure during CRYSTAL-FACE",2003,"10.1029/2003JD003582","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36549038048&doi=10.1029%2f2003JD003582&partnerID=40&md5=aee0e279ea3a016ed4949249da252f97","During July 2002, measurements of cloud condensation nuclei were made in the vicinity of southwest Florida as part of the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign. These observations, at supersaturations of 0.2 and 0.85%, are presented here. The performance of each of the two CCN counters was validated through laboratory calibration and an in situ intercomparison. The measurements indicate that the aerosol sampled during the campaign was predominantly marine in character: the median concentrations were 233 cm-3 (at S = 0.2%) and 371 cm-3 (at S = 0.85%). Three flights during the experiment differed from this general trend; the aerosol sampled during the two flights on 18 July was more continental in character, and the observations on 28 July indicate high spatial variability and periods of very high aerosol concentrations. This study also includes a simplified aerosol/CCN closure analysis. Aerosol size distributions were measured simultaneously with the CCN observations, and these data are used to predict a CCN concentration using Köhler theory. For the purpose of this analysis, an idealized composition of pure ammonium sulfate was assumed. The analysis indicates that in this case, there was good general agreement between the predicted and observed CCN concentrations: at S= 0.2%, N<inf>predicted</inf>/N<inf>observed</inf> = 1.047 (R2 = 0.911); at S = 0.85%, N<inf>predicted</inf>/N <inf>observed</inf> = 1.201 (R2 = 0.835). The impacts of the compositional assumption and of including in-cloud data in the analysis are addressed. The effect of removing the data from the 28 July flight is also examined; doing so improves the result of the closure analysis at S = 0.85%. When omitting that atypical flight, N<inf>predicted</inf>/N<inf>observed</inf> = 1.085 (R2 = 0.770) at S = 0.85%. Copyright 2003 by the American Geophysical Union."
"34881780600;6506328135;36868795400;37099564300;56583515100;8247122100;","Mechanisms of convective cloud organization by cold pools over tropical warm ocean during the AMIE/DYNAMO field campaign",2015,"10.1002/2014MS000384","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027952454&doi=10.1002%2f2014MS000384&partnerID=40&md5=8709ad51eeaf0dd28137b2ce2cb21759","This paper investigates the mechanisms of convective cloud organization by precipitation-driven cold pools over the warm tropical Indian Ocean during the 2011 Atmospheric Radiation Measurement (ARM) Madden-Julian Oscillation (MJO) Investigation Experiment/Dynamics of the MJO (AMIE/DYNAMO) field campaign. A high-resolution regional model simulation is performed using the Weather Research and Forecasting model during the transition from suppressed to active phases of the November 2011 MJO. The simulated cold pool lifetimes, spatial extent, and thermodynamic properties agree well with the radar and ship-borne observations from the field campaign. The thermodynamic and dynamic structures of the outflow boundaries of isolated and intersecting cold pools in the simulation and the associated secondary cloud populations are examined. Intersecting cold pools last more than twice as long, are twice as large, 41% more intense (measured with buoyancy), and 62% deeper than isolated cold pools. Consequently, intersecting cold pools trigger 73% more convection than do isolated ones. This is due to stronger outflows that enhance secondary updraft velocities by up to 45%. However, cold pool-triggered convective clouds grow into deep convection not because of the stronger secondary updrafts at cloud base, but rather due to closer spacing (aggregation) between clouds and larger cloud clusters that form along the cold pool boundaries when they intersect. The close spacing of large clouds moistens the local environment and reduces entrainment drying, increasing the probability that the clouds further develop into deep convection. Implications for the design of future convective parameterization with cold pool-modulated entrainment rates are discussed. Key Points: Intersecting cold pools trigger more clouds than isolated ones Intersecting cold pools produce larger clouds and closer spacing among them Larger clouds and closer spacing promote deeper convection © 2015. The Authors."
"7407016988;7004369046;55940978200;7102609908;","Sounding-based thermodynamic budgets for DYNAMO",2015,"10.1175/JAS-D-14-0202.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923106974&doi=10.1175%2fJAS-D-14-0202.1&partnerID=40&md5=a9d65c735e782c55ed4b499e772761aa","The Dynamics of theMadden-Julian Oscillation (DYNAMO) field campaign, conducted over the Indian Ocean from October 2011 to March 2012, was designed to study the initiation of the Madden-Julian oscillation (MJO). Two prominentMJOs occurred in the experimental domain during the special observing period in October and November. Data from a northern and a southern sounding array (NSA and SSA, respectively) have been used to investigate the apparent heat sources and sinks (Q1 and Q2) and radiative heating rates QR throughout the life cycles of the two MJO events. The MJO signal was far stronger in the NSA than the SSA. Time series of Q1, Q2, and the vertical eddy flux of moist static energy reveal an evolution of cloud systems for both MJOs consistent with prior studies: shallow, nonprecipitating cumulus during the suppressed phase, followed by cumulus congestus, then deep convection during the active phase, and finally stratiform precipitation. However, the duration of these phases was shorter for the November MJO than for the October event. The profiles of Q1 and Q2 for the two arrays indicate a greater stratiform rain fraction for the NSA than the SSA-a finding supported by TRMM measurements. Surface rainfall rates and net tropospheric QR determined as residuals from the budgets show good agreement with satellite-based estimates. The cloud radiative forcing was approximately 20% of the column-integrated convective heating and of the same amplitude as the normalized gross moist stability, leaving open the possibility of radiative-convective instability for the two MJOs. © 2015 American Meteorological Society."
"7005453641;35472747700;37057068400;7006717176;","The 2009-2010 Arctic polar stratospheric cloud season: A CALIPSO perspective",2011,"10.5194/acp-11-2161-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79952422106&doi=10.5194%2facp-11-2161-2011&partnerID=40&md5=c03362159f81cdf8c1992f8695761cf5","Spaceborne lidar measurements from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) are used to provide a vortex-wide perspective of the 2009-2010 Arctic PSC (polar stratospheric cloud) season to complement more focused measurements from the European Union RECONCILE (reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) field campaign. The 2009-2010 Arctic winter was unusually cold at stratospheric levels from mid-December 2009 until the end of January 2010, and was one of only a few winters from the past fifty-two years with synoptic-scale regions of temperatures below the frost point. More PSCs were observed by CALIPSO during the 2009-2010 Arctic winter than in the previous three Arctic seasons combined. In particular, there were significantly more observations of high number density NAT (nitric acid trihydrate) mixtures (referred to as Mix 2-enh) and ice PSCs. We found that the 2009-2010 season could roughly be divided into four periods with distinctly different PSC optical characteristics. The early season (15-30 December 2009) was characterized by patchy, tenuous PSCs, primarily low number density liquid/NAT mixtures. No ice clouds were observed by CALIPSO during this early phase, suggesting that these early season NAT clouds were formed through a non-ice nucleation mechanism. The second phase of the season (31 December 2009-14 January 2010) was characterized by frequent mountain wave ice clouds that nucleated widespread NAT particles throughout the vortex, including Mix 2-enh. The third phase of the season (15-21 January 2010) was characterized by synoptic-scale temperatures below the frost point which led to a rare outbreak of widespread ice clouds. The fourth phase of the season (22-28 January) was characterized by a major stratospheric warming that distorted the vortex, displacing the cold pool from the vortex center. This final phase was dominated by STS (supercooled ternary solution) PSCs, although NAT particles may have been present in low number densities, but were masked by the more abundant STS droplets at colder temperatures. We also found distinct variations in the relative proportion of PSCs in each composition class with altitude over the course of the 2009-2010 Arctic season. Lower number density liquid/NAT mixtures were most frequently observed in the lower altitude regions of the clouds (below ∼18-20 km), which is consistent with CALIPSO observations in the Antarctic. Higher number density liquid/NAT mixtures, especially Mix 2-enh, were most frequently observed at altitudes above 18-20 km, primarily downstream of wave ice clouds. This pattern is consistent with the conceptual model whereby low number density, large NAT particles are precipitated from higher number density NAT clouds (i.e. mother clouds) that are nucleated downstream of mountain wave ice clouds. © 2011 Author(s)."
"36458602300;22236015300;56690386600;6602515941;6603431534;22980018800;","Observed relations between snowfall microphysics and triple-frequency radar measurements",2015,"10.1002/2015JD023156","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955663455&doi=10.1002%2f2015JD023156&partnerID=40&md5=5e091deec19492a398376c722269b975","Recently published studies of triple-frequency radar observations of snowfall have demonstrated that naturally occurring snowflakes exhibit scattering signatures that are in some cases consistent with spheroidal particle models and in others can only be explained by complex aggregates. Until recently, no in situ observations have been available to investigate links between microphysical snowfall properties and their scattering properties. In this study, we investigate for the first time relations between collocated ground-based triple-frequency observations with in situ measurements of snowfall at the ground. The three analyzed snowfall cases obtained during a recent field campaign in Finland cover light to moderate snowfall rates with transitions from heavily rimed snow to open-structured, low-density snowflakes. The observed triple-frequency signatures agree well with the previously published findings from airborne radar observations. A rich spatiotemporal structure of triple-frequency observations throughout the cloud is observed during the three cases, which often seems to be related to riming and aggregation zones within the cloud. The comparison of triple-frequency signatures from the lowest altitudes with the ground-based in situ measurements reveals that in the presence of large (>5 mm) snow aggregates, a bending away in the triple-frequency space from the curve of classical spheroid scattering models is always observed. Rimed particles appear along an almost horizontal line in the triple-frequency space, which was not observed before. Overall, the three case studies indicate a close connection of triple-frequency signatures and snow particle structure, bulk snowfall density, and characteristic size of the particle size distribution. © 2015. American Geophysical Union. All Rights Reserved."
"55614112000;7003283811;7003626306;35331137500;6508361903;","A 94-GHz cloud radar system on a NASA high-altitude ER-2 aircraft",2004,"10.1175/1520-0426(2004)021<1378:AGCRSO>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-5044223527&doi=10.1175%2f1520-0426%282004%29021%3c1378%3aAGCRSO%3e2.0.CO%3b2&partnerID=40&md5=441e4c1959fd1aed0b444b2d25fc6b3d","The 94-GHz (W band) Cloud Radar System (CRS) has been developed and flown on a NASA ER-2 high-altitude (20 km) aircraft. The CRS is a fully coherent, polarimetric Doppler radar that is capable of detecting clouds and precipitation from the surface up to the aircraft altitude in the lower stratosphere. The radar is especially well suited for cirrus cloud studies because of its high sensitivity and fine spatial resolution. This paper describes the CRS motivation, instrument design, specifications, calibration, and preliminary data from NASA's Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign. The unique combination of CRS with other sensors on the ER-2 provides an unprecedented opportunity to study cloud radiative effects on the global energy budget. CRS observations are being used to improve our knowledge of atmospheric scattering and attenuation characteristics at 94 GHz, and to provide datasets for algorithm implementation and validation for the upcoming NASA CloudSat mission that will use a 94-GHz spaceborne cloud radar to provide the first direct global survey of the vertical structure of cloud systems. © 2004 American Meteorological Society."
"7202429440;7201432984;","North American, Asian, and Indian haze: Similar regional impacts on climate?",2003,"10.1029/2003GL016934","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042412176&doi=10.1029%2f2003GL016934&partnerID=40&md5=a0cab208d7594428b096f70e6ec9200c","Pollution plumes recur seasonally downwind of the Indian subcontinent and Asian continent due to industrial and vehicular emissions, biomass burning, and wind-blown dust. These plumes have been well documented by field campaigns and satellite observations and the environmental implications of the ""Asian Brown Cloud"" have been widely publicized in a recently released UNEP report [UNEP and C4, 2002]. Recent field experiments, however, demonstrate that the U.S. pollution plume can be as intense (in terms of aerosol mass concentration, aerosol optical depth, and ozone mixing ratio) as those downwind of India and Asia affecting regional climate along the U.S. East Coast. The use of identical sampling protocols in these experiments has been key in eliminating sampling biases and making the data directly comparable."
"7102866124;57201177267;7202530955;7005206400;23096443800;13408938100;7402115506;54781196300;25924706200;7004114883;7410009029;7004436916;14019431100;57208083053;14037044200;6602176524;7102643810;35228711600;7006263526;6603778635;8612873400;12240204600;7006790175;6602420251;8691681600;6701858531;7404350742;10144282600;8612873300;6701653010;","The CHUVA project: How does convection vary across Brazil?",2014,"10.1175/BAMS-D-13-00084.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84899637722&doi=10.1175%2fBAMS-D-13-00084.1&partnerID=40&md5=675d3f80c19af3b40bf693e9bc6d43c7","CHUVA reveals very diverse cloud processes in tropical continental regions and contributes to improving satellite precipitation estimation, nowcasting, cloud-resolving models, and the understanding of cloud electrification. The acronym for CHUVA is Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (GPM). The CHUVA field campaigns, in addition to their focus on the microphysical properties of tropical clouds, have an important role in improving existing algorithms for precipitation retrieval for the GPM mission. CHUVA's principal motivation is the description and understanding of the cloud processes of the various precipitation regimes of Brazil. CHUVA consists of six field campaigns, five of which have already taken place. The sixth will be carried out in 2014 in Manaus as part of the GoAmazon initiative. The CHUVA website is the primary access to the CHUVA information and data. For each campaign, a specific web page was developed. These web pages contain a wide variety of information, including the daily weather report, instrument strategy, instrument locations, quick looks of the main events, data reports, cloud pictures, and the Severe Storm Observation System CHUVA."
"7005729142;6506385754;7003283811;15135583300;","Microphysics of maritime tropical convective updrafts at temperatures from 22° to 26°C",2009,"10.1175/2009JAS3107.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77951848462&doi=10.1175%2f2009JAS3107.1&partnerID=40&md5=b54267545786dcd4b8a82fcba4d87f4b","Anvils produced by vigorous tropical convection contribute significantly to the earth's radiation balance, and their radiative properties depend largely on the concentrations and sizes of the ice particles that form them. These microphysical properties are determined to an important extent by the fate of supercooled droplets, with diameters from 3 to about 20 microns, lofted in the updrafts. The present study addresses the question of whether most or all of these droplets are captured by ice particles or if they remain uncollected until arriving at the -38°C level where they freeze by homogeneous nucleation, producing high concentrations of very small ice particles that can persist and dominate the albedo. Aircraft data of ice particle and water droplet size distributions from seven field campaigns at latitudes from 25°N to 11°S are combined with a numerical model in order to examine the conditions under which significant numbers of supercooled water droplets can be lofted to the homogeneous nucleation level. Microphysical data were collected in pristine to heavily dust-laden maritime environments, isolated convective updrafts, and tropical cyclone updrafts with peak velocities reaching 25 m s21. The cumulative horizontal distance of incloud sampling at temperatures of -20°C and below exceeds 50 000 km. Analysis reveals that most of the condensate in these convective updrafts is removed before reaching the-20°C level, and the total condensate continues to diminish linearly upward. The amount of condensate in small (&lt;50 μm in diameter) droplets and ice particles, however, increases upward, suggesting new droplet activation with an appreciable radiative impact. Conditions promoting the generation of large numbers of small ice particles through homogeneous ice nucleation include high concentrations of cloud condensation nuclei (sometimes from dust), removal of most of the water substance between cloud base and the -38°C levels, and acceleration of the updrafts at mid- and upper levels such that velocities exceed 5-7 m s-1. © 2009 American Meteorological Society."
"8511991900;7202048112;7004715270;7006303509;55544607500;7102084129;35276210200;7404187535;7005773698;7006783796;8280879000;7004057920;","Aerosol impacts on California winter clouds and precipitation during calwater 2011: Local pollution versus long-range transported dust",2014,"10.5194/acp-14-81-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84891691818&doi=10.5194%2facp-14-81-2014&partnerID=40&md5=2434bbf3eb354be07419c0f3a6cd1e94","Mineral dust aerosols often observed over California in winter and spring, associated with long-range transport from Asia and the Sahara, have been linked to enhanced precipitation based on observations. Local anthropogenic pollution, on the other hand, was shown in previous observational and modeling studies to reduce precipitation. Here we incorporate recent developments in ice nucleation parameterizations to link aerosols with ice crystal formation in a spectral-bin cloud microphysical model coupled with the Weather Research and Forecasting (WRF) model in order to examine the relative and combined impacts of dust and local pollution particles on cloud properties and precipitation type and intensity. Simulations are carried out for two cloud cases (from the CalWater 2011 field campaign) with contrasting meteorology and cloud dynamics that occurred on 16 February (FEB16) and 2 March (MAR02). In both cases, observations show the presence of dust and biological particles in a relative pristine environment. The simulated cloud microphysical properties and precipitation show reasonable agreement with aircraft and surface measurements. Model sensitivity experiments indicate that in the pristine environment, the dust and biological aerosol layers increase the accumulated precipitation by 10-20% from the Central Valley to the Sierra Nevada for both FEB16 and MAR02 due to a ∼40% increase in snow formation, validating the observational hypothesis. Model results show that local pollution increases precipitation over the windward slope of the mountains by a few percent due to increased snow formation when dust is present, but reduces precipitation by 5-8% if dust is removed on FEB16. The effects of local pollution on cloud microphysics and precipitation strongly depend on meteorology, including cloud dynamics and the strength of the Sierra Barrier Jet. This study further underscores the importance of the interactions between local pollution, dust, and environmental conditions for assessing aerosol effects on cold-season precipitation in California. © 2014 Author(s) ."
"7004091067;7005773698;7005265210;8147766700;7004715270;7004651463;22975069200;7202048112;7102084129;7005461477;7003278104;7404187535;14018977200;55968364300;57203247274;6603746990;","Calwater field studies designed to quantify the roles of atmospheric rivers and aerosols in modulating U.S. West Coast Precipitation in a changing climate",2016,"10.1175/BAMS-D-14-00043.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984844782&doi=10.1175%2fBAMS-D-14-00043.1&partnerID=40&md5=fc9f6024e237dad4062d1c2d4beadf7d","The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region's economy and environment, as evidenced by the recent California drought. This variability is strongly influenced by atmospheric rivers (ARs), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, and by aerosols (from local sources and transported from remote continents and oceans) that modulate clouds and precipitation. A better understanding of these processes is needed to reduce uncertainties in weather predictions and climate projections of droughts and floods, both now and under changing climate conditions. To address these gaps, a group of meteorologists, hydrologists, climate scientists, atmospheric chemists, and oceanographers have created an interdisciplinary research effort, with support from multiple agencies. From 2009 to 2011 a series of field campaigns [California Water Service (CalWater) 1] collected atmospheric chemistry, cloud microphysics, and meteorological measurements in California and associated modeling and diagnostic studies were carried out. Based on the remaining gaps, a vision was developed to extend these studies offshore over the eastern North Pacific and to enhance land-based measurements from 2014 to 2018 (CalWater-2). The dataset and selected results from CalWater-1 are summarized here. The goals of CalWater-2, and measurements to date, are then described. CalWater is producing new findings and exploring new technologies to evaluate and improve global climate models and their regional performance and to develop tools supporting water and hydropower management. These advances also have potential to enhance hazard mitigation by improving near-term weather prediction and subseasonal and seasonal outlooks. ©2016 American Meteorological Society."
"7403401100;6701378450;57196499374;35461763400;","Impact of biomass burning on cloud properties in the Amazon Basin",2003,"10.1029/2001jd000985","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347899424&doi=10.1029%2f2001jd000985&partnerID=40&md5=abebaac8a569cdf6a85a6f23ce32e9bd","We used a one-dimensional (1-D) cloud parcel model to assess the impact of biomass-burning aerosol on cloud properties in the Amazon Basin and to identify the physical and chemical properties of the aerosol that influence droplet growth. Cloud condensation nuclei (CCN) measurements were performed between 0.15% and 1.5% supersaturation at ground-based sites in the states of Amazonas and Rondônia, Brazil during several field campaigns in 1998 and 1999 as part of the Large-Scale Biosphere Atmosphere (LBA) Experiment in Amazonia. CCN concentrations measured during the wet season were low and resembled concentrations more typical of marine conditions than most continental sites. During the dry season, smoke aerosol from biomass burning dramatically increased CCN concentrations. The modification of cloud properties, such as cloud droplet effective radius and maximum supersaturation, is most sensitive at low CCN concentrations. Hence, we could expect larger interannual variation of cloud properties during the wet season that the dry season. We found that differences between CCN spectra from forested and deforested regions during the wet season are modest and result in modifications of cloud properties that are small compared to those between wet and dry seasons. Our study suggests that the differences in surface albedo, rather than cloud albedo, between forested and deforested regions may dominate the impact of deforestation on the hydrological cycle and convective activity during the wet season. During the dry season, on the other hand, cloud droplet concentrations may increase by up to 7 times, which leads to a model-predicted decrease in cloud effective radius by a factor of 2. This could imply a maximum indirect radiative forcing due to aerosol as high as ca. -27 W m-2 for a nonabsorbing cloud. Light-absorbing substances in smoke darken the Amazonian clouds and reduce the net radiative forcing, and a comparison of the Advanced Very High Resolution Radiometer (AVHRR) analysis and our modeling studies suggests that absorption of sunlight due to smoke aerosol may compensate for about half of the maximum aerosol effect. Sensitivity tests show that complete characterization of the aerosol is necessary when kinetic growth limitations become important. Subtle differences in the chemical and physical makeup are shown to be particularly influential in the activation and growth behavior of the aerosol. Knowledge of the CCN spectrum alone is not sufficient to fully capture the climatic influence of biomass burning."
"56374442600;9432343100;7102680152;55512417200;7004047498;54410864500;22837162400;7003720206;7403204849;7006415284;7402177459;7006595513;","Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign",2013,"10.5194/acp-13-7983-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882587827&doi=10.5194%2facp-13-7983-2013&partnerID=40&md5=8533d0de77da52fa03bbc33ab9e60b61","Particle hygroscopic growth at 90% RH (relative humidity), cloud condensation nuclei (CCN) activity, and size-resolved chemical composition were concurrently measured in the Thüringer Wald mid-level mountain range in central Germany in the fall of 2010. The median hygroscopicity parameter values, κ, of 50, 75, 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.14, 0.14, 0.17, 0.21, 0.24, and 0.28 during the sampling period. The closure between HTDMA (Hygroscopicity Tandem Differential Mobility Analyzers)-measured (κHTDMA) and chemical composition-derived (κchem) hygroscopicity parameters was performed based on the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. Using size-averaged chemical composition, the κ values are substantially overpredicted (30 and 40% for 150 and 100 nm particles). Introducing size-resolved chemical composition substantially improved closure. We found that the evaporation of NH4NO3, which may happen in a HTDMA system, could lead to a discrepancy in predicted and measured particle hygroscopic growth. The hygroscopic parameter of the organic fraction, κorg, is positively correlated with the O : C ratio (κorg =0.19 × (O : C) - 0.03). Such correlation is helpful to define the κorg value in the closure study. κ derived from CCN measurement was around 30% (varied with particle diameters) higher than that determined from particle hygroscopic growth measurements (here, hydrophilic mode is considered only). This difference might be explained by the surface tension effects, solution non-ideality, gas-particle partitioning of semivolatile compounds, and the partial solubility of constituents or non-dissolved particle matter. Therefore, extrapolating from HTDMA data to properties at the point of activation should be done with great care. Finally, closure study between CCNc (cloud condensation nucleus counter)-measured (κCCN) and chemical composition (κCCN, chem) was performed using CCNc-derived κ values for individual components. The results show that the κCCN can be well predicted using particle size-resolved chemical composition and the ZSR mixing rule.© Author(s) 2013."
"35547214900;36155531100;7202108879;7003283811;6602407753;7003626306;35331137500;7202016984;7003865921;","Combined lidar-radar remote sensing: Initial results from CRYSTAL-FACE",2004,"10.1029/2003jd004030","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942528900&doi=10.1029%2f2003jd004030&partnerID=40&md5=af3d5d2744ce7a31702896cdd79ef7dc","In the near future, NASA plans to fly satellites carrying a two-wavelength polarization lidar and a 94-GHz cloud profiling radar in formation to provide complete global profiling of cloud and aerosol properties. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign, conducted during July 2002, provided the first high-altitude collocated measurements from lidar and cloud profiling radar to simulate these spaceborne sensors. The lidar and radar provide complementary measurements with varying degrees of vertical measurement overlap within cloud layers. This paper presents initial results of the combined airborne lidar-radar measurements during CRSYTAL-FACE. A comparison of instrument sensitivity is presented within the context of particular CRYSTAL-FACE observations. It was determined that optically thin cirrus clouds are frequently missed by the radar but are easily profiled with the lidar. In contrast, optically thick clouds and convective cores quickly extinguish the lidar signal but are easily probed with the radar. Results are presented to quantify the portion of atmospheric features sensed independently by each instrument and the portion sensed simultaneously by the two instruments. To capture some element of varying atmospheric characteristics, two cases are analyzed, one with convective systems and one having synoptic cirrus and considerable clear air. The two cases show quite different results, primarily due to differences in cloud microphysics."
"6701653010;56597519200;7102024878;57203859138;7006253794;","Measurements of drop size distribution in the southwestern Amazon basin",2002,"10.1029/2001JD000355","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448950903&doi=10.1029%2f2001JD000355&partnerID=40&md5=ccffd6f828eab26525161ad8151c689a","Simultaneous observations of an optical and an impact type disdrometer and their application in radar rainfall estimation are evaluated. The disdrometers and two collocated rain gauges were operated in the southwest Amazon region of Brazil in 1999 as part of a NASA Tropical Rainfall Measuring Mission (TRMM) field campaign and the hydrometeorological component of the Large Scale Biosphere-Atmosphere Experiment (LBA). During the experiment, we observed large drops with diameters greater than 5 mm. These large drops were not adequately detected by the impact disdrometer and resulted in differences in drop size distribution and integral rain parameters derived from the two sensors. Considering coincident observations, we calculated that the impact disdrometer recorded about 11% lower rainfall accumulations than the optical disdrometer. In addition, radar rainfall algorithms, which we derived from the impact and optical disdrometer measurements, showed instrument dependency. Out of four radar rainfall algorithms that we considered, rain rate derived from specific differential phase has the least dependency, while the rain rate derived from reflectivity at horizontal polarization and differential reflectivity combined exhibited the largest. We also observed the characteristics of rainfall and drop size distribution in two distinct wind regimes present during the TRMM-LBA field campaign. Rain was heavier in the easterly regime, with more large drops being present. Copyright 2002 by the American Geophysical Union."
"6602999057;57204288222;","Mineral dust: A key player in the earth system",2014,"10.1007/978-94-017-8978-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84930911536&doi=10.1007%2f978-94-017-8978-3&partnerID=40&md5=4409d355472aec2554b789b645d9d1d5","This volume presents state-of-the-art research about mineral dust, including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies. Dust research is a new, dynamic and fast-growing area of science and due to its multiple roles in the Earth system, dust has become a fascinating topic for many scientific disciplines. Aspects of dust research covered in this book reach from timescales of minutes (as with dust devils, cloud processes and radiation) to millennia (as with loess formation and oceanic sediments), making dust both a player and recorder of environmental change. The book is structured in four main parts that explore characteristics of dust, the global dust cycle, impacts of dust on the Earth system, and dust as a climate indicator. The chapters in these parts provide a comprehensive, detailed overview of this highly interdisciplinary subject. The contributions presented here cover dust from source to sink and describe all the processes dust particles undergo while travelling through the atmosphere. Chapters explore how dust is lifted and transported, how it affects radiation, clouds, regional circulations, precipitation and chemical processes in the atmosphere and how it deteriorates air quality. The book explores how dust is removed from the atmosphere by gravitational settling, turbulence or precipitation, how iron contained in dust fertilizes terrestrial and marine ecosystems, and about the role that dust plays in human health. We learn how dust is observed, simulated using computer models and forecast. The book also details the role of dust deposits for climate reconstructions. Scientific observations and results are presented, along with numerous illustrations. This work has an interdisciplinary appeal and will engage scholars in geology, geography, chemistry, meteorology and physics, amongst others with an interest in the Earth system and environmental change. © 2014 Springer Science+Business Media Dordrecht. All rights are reserved."
"7102084129;6701922947;15318942300;23987289400;7402565763;9243831600;","Aircraft measurements of the impacts of pollution aerosols on clouds and precipitation over the Sierra Nevada",2008,"10.1029/2007JD009544","https://www.scopus.com/inward/record.uri?eid=2-s2.0-71949103630&doi=10.1029%2f2007JD009544&partnerID=40&md5=576bf24d4c1b90fb077d34e37bea5c2d","Recent publications suggest that anthropogenic aerosols suppress orographic precipitation in California and elsewhere. A field campaign (SUPRECIP: Suppression of Precipitation) was conducted to investigate this hypothesized aerosol effect. The campaign consisted of in situ aircraft measurements of the polluting aerosols, the composition of the clouds ingesting them, and the way the precipitation-forming processes are affected. SUPRECIP was conducted during February and March of 2005 and February and March of 2006. The flights documented the aerosols and orographic clouds flowing into the central Sierra Nevada from the upwind densely populated industrialized/urbanized areas and contrasted them with the aerosols and clouds downwind of the sparsely populated areas in the northern Sierra Nevada. SUPRECIP found that the aerosols transported from the coastal regions are augmented greatly by local sources in the Central Valley resulting in high concentrations of aerosols in the eastern parts of the Central Valley and the Sierra foothills. This pattern is consistent with the detected patterns of suppressed orographic precipitation, occurring primarily in the southern and central Sierra Nevada, but not in the north. The precipitation suppression occurs mainly in the orographic clouds that are triggered from the boundary layer over the foothills and propagate over the mountains. The elevated orographic clouds that form at the crest are minimally affected. The clouds are affected mainly during the second half of the day and the subsequent evening, when solar heating mixes the boundary layer up to cloud bases. Local, yet unidentified nonurban sources are suspected to play a major role. Copyright 2008 by the American Geophysical Union."
"35547214900;6602407753;7202108879;35463545000;55470017900;","Airborne lidar measuremens of aerosol optical properties during SAFARI-2000",2003,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345045166&partnerID=40&md5=f4c59a0b365f2877a64435f9d3b01dc1","The Cloud Physics Lidar (CPL) operated onboard the NASA ER-2 high-altitude aircraft during the Southern African Regional Science Initiative (SAFARI)-2000 field campaign. The CPL provided high spatial resolution estimates of aerosol optical properties at both 1064 and 532 nm. We present here results of planetary boundary layer (PBL) aerosol optical depth analysis and profiles of aerosol extinction. Variation of optical depth and extinction are examined as a function of regional location. The wide-scale aerosol mapping obtained by the CPL is a unique data set that will aid in future studies aerosol transport. Comparisons between the airborne CPL and ground-based Micro-Pulse Lidar Network (MPL-Net) sites are shown to have good agreement."
"42662217100;6603431534;19337612500;24722339600;","Marine boundary layer cloud observations in the Azores",2012,"10.1175/JCLI-D-11-00610.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870051148&doi=10.1175%2fJCLI-D-11-00610.1&partnerID=40&md5=7cfedd9ca11fc1e352779db5a1163ee3","The recent deployment of the Atmospheric Radiation Measurement Program (ARM) Mobile Facility at Graciosa Island, Azores, in the context of the Clouds, Aerosol and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign added the most extensive (19 months) and comprehensive dataset of marine boundary layer (MBL) clouds to date. Cloud occurrence is high (60%-80%), with a summertime minimum. Liquid precipitation is frequently present (30%-40%), mainly in the form of virga. Boundary layer clouds are themost frequently observed cloud type (40%-50%) with a maximum of occurrence during the summer and fall months under the presence of anticyclonic conditions. Cumulus clouds are the most frequently occurring MBL cloud type (20%) with cumulus under stratocumulus layers (10%-30%) and single-layer stratocumulus (0%-10%) following in frequency of occurrence. A stable transition layer in the subcloud layer is commonly observed (92% of the soundings). Cumulus cloud bases and stratocumulus cloud tops correlate very well with the top of the transition layer and the inversion base, respectively. Drizzling stratocumulus layers are thicker (350-400 m) and have higher liquid water path (75-150 g m-2) than their nondrizzling counterparts (100-250 m and 30-75 g m-2, respectively). The variance of the vertical air motion is maximum near the cloud base and is higher at night. The updraftmass flux is around 0.17 kg m-2 s-1 with 40%-60%explained by coherent updraft structures. Despite a high frequency of stratocumulus clouds in the Azores, theMBL is almost never well mixed and is often cumulus coupled. © 2012 American Meteorological Society."
"7003875148;34976155900;7005753600;7003663305;9038337500;24472110700;8696069500;7003740015;7003900383;7801558983;55327762400;","Meteorological conditions in the central Arctic summer during the Arctic Summer Cloud Ocean Study (ASCOS)",2012,"10.5194/acp-12-6863-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84864590873&doi=10.5194%2facp-12-6863-2012&partnerID=40&md5=c2ff726b874dd48a06d06a0c0653f93a","Understanding the rapidly changing climate in the Arctic is limited by a lack of understanding of underlying strong feedback mechanisms that are specific to the Arctic. Progress in this field can only be obtained by process-level observations; this is the motivation for intensive ice-breaker-based campaigns such as the Arctic Summer Cloud-Ocean Study (ASCOS), described here. However, detailed field observations also have to be put in the context of the larger-scale meteorology, and short field campaigns have to be analysed within the context of the underlying climate state and temporal anomalies from this. <br><br> To aid in the analysis of other parameters or processes observed during this campaign, this paper provides an overview of the synoptic-scale meteorology and its climatic anomaly during the ASCOS field deployment. It also provides a statistical analysis of key features during the campaign, such as key meteorological variables, the vertical structure of the lower troposphere and clouds, and energy fluxes at the surface. In order to assess the representativity of the ASCOS results, we also compare these features to similar observations obtained during three earlier summer experiments in the Arctic Ocean: the AOE-96, SHEBA and AOE-2001 expeditions. <br><br> We find that these expeditions share many key features of the summertime lower troposphere. Taking ASCOS and the previous expeditions together, a common picture emerges with a large amount of low-level cloud in a well-mixed shallow boundary layer, capped by a weak to moderately strong inversion where moisture, and sometimes also cloud top, penetrate into the lower parts of the inversion. Much of the boundary-layer mixing is due to cloud-top cooling and subsequent buoyant overturning of the cloud. The cloud layer may, or may not, be connected with surface processes depending on the depths of the cloud and surface-based boundary layers and on the relative strengths of surface-shear and cloud-generated turbulence. The latter also implies a connection between the cloud layer and the free troposphere through entrainment at cloud top. © 2012 Author(s)."
"8390588100;57203382356;16445028400;15922450100;6602890094;56054157600;17341189400;7403401100;6603931046;7003854090;7005219614;6602675083;7006863273;7402365467;15069732800;7004864963;35461763400;","Impact of Manaus City on the Amazon Green Ocean atmosphere: Ozone production, precursor sensitivity and aerosol load",2010,"10.5194/acp-10-9251-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77957579002&doi=10.5194%2facp-10-9251-2010&partnerID=40&md5=0d0323c00e125e1972156b3204ec31bb","As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O3, NO, NO 2, CO, VOC, CO2, and H2O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h -1. Within the plume core, aerosol concentrations were strongly enhanced, with ΔCN/ΔCO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. ΔCN/ΔCO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large fraction of the total particle number served as CCN (about 60-80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16±12%) of the plume particles were CCN. The fresh plume aerosols showed relatively weak light scattering efficiency. The CO-normalized CCN concentrations and light scattering coefficients increased with plume age in most cases, suggesting particle growth by condensation of soluble organic or inorganic species. We used a Single Column Chemistry and Transport Model (SCM) to infer the urban pollution emission fluxes of Manaus City, implying observed mixing ratios of CO, NOx and VOC. The model can reproduce the temporal/spatial distribution of ozone enhancements in the Manaus plume, both with and without accounting for the distinct (high NOx) contribution by the power plants; this way examining the sensitivity of ozone production to changes in the emission rates of NOx. The VOC reactivity in the Manaus region was dominated by a high burden of biogenic isoprene from the background rainforest atmosphere, and therefore NOx control is assumed to be the most effective ozone abatement strategy. Both observations and models show that the agglomeration of NOx emission sources, like power plants, in a well-arranged area can decrease the ozone production efficiency in the near field of the urban populated cores. But on the other hand remote areas downwind of the city then bear the brunt, being exposed to increased ozone production and N-deposition. The simulated maximum stomatal ozone uptake fluxes were 4 nmol m-2 s-1 close to Manaus, and decreased only to about 2 nmol m -2 s-1 within a travel distance &gt;1500 km downwind from Manaus, clearly exceeding the critical threshold level for broadleaf trees. Likewise, the simulated N deposition close to Manaus was ∼70 kg N ha -1 a-1 decreasing only to about 30 kg N ha-1 a-1 after three days of simulation. © Author(s) 2010."
"16833477000;6603957672;23011284400;12785704900;57203174863;7006960661;","Retrieval of aerosol optical properties from OMI radiances using a multiwavelength algorithm: Application to western Europe",2008,"10.1029/2007JD008738","https://www.scopus.com/inward/record.uri?eid=2-s2.0-56349158765&doi=10.1029%2f2007JD008738&partnerID=40&md5=b3643c7e2f75bef950d5532565522042","The Ozone Monitoring Instrument (OMI) multiwavelength algorithm has been developed to retrieve aerosol optical depth using OMI-measured reflectance at the top of the atmosphere. This algorithm was further developed by using surface reflectance data from a field campaign in Cabauw (The Netherlands), a new cloud-sereening method, and a global aerosol database derived from the aerosol transport model TM5. The first results from an application of this algorithm over western Europe are presented. The OMI-retrieved aerosol optical depth is evaluated by comparison with both ground-based measurements from Aerosol Robotic Network (AERONET) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. The various aerosol optical depth values compare favorably, except in situations where large changes occur in the surface properties, which is illustrated over the Iberian peninsula. OMI and MODIS aerosol optical depth are well correlated (with a correlation coefficient of 0.66 over land and 0.79 over sea), although the multiwavelength algorithm appears to overestimate the aerosol optical depth values with respect to MODIS. The multiwavelength algorithm performs better over sea than over land. Qualitatively, the multiwavelength algorithm well reproduces the expected spatial aerosol optical depth gradient over western Europe. Copyright 2008 by the American Geophysical Union."
"7404187535;57198690320;7004449177;7004091067;6603487276;","Extending the dynamic range of an S-band radar for cloud and precipitation studies",2000,"10.1175/1520-0426(2000)017<1226:ETDROA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033652403&doi=10.1175%2f1520-0426%282000%29017%3c1226%3aETDROA%3e2.0.CO%3b2&partnerID=40&md5=e3072f6e05aa8a9039d468a85f6842f5","A new S-band vertical profiler with a coupler option for extending the dynamic range of the radar's receiver is discussed. The added dynamic range allows the profiler to record radar reflectivity measurements in moderate to heavy precipitation that otherwise would not have been possible with this system because of receiver saturation. The radar hardware, signal processor, and operating software are based on existing S-band and UHF profiler technology. Results from a side-by-side comparison with a calibrated Ka-band radar are used to determine the calibration and sensitivity of the S-band profiler. In a typical cloud profiling mode of operation, the sensitivity is - 14 dBZ at 10 km. Examples taken from a recent field campaign are shown to illustrate the profiler's ability to measure vertical velocity and radar reflectivity profiles in clouds and precipitation, with particular emphasis on the benefit provided by the coupler technology."
"7006329853;6701865015;","Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS)",1998,"10.1029/98GL00839","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032522311&doi=10.1029%2f98GL00839&partnerID=40&md5=04bb8cc5e1853ffb8d3eb873dc5fe529","The Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) was a multi-aircraft field campaign which took place in April and May of 1996, over the Central and Western United States. The goal of SUCCESS was to learn more about Earth's radiative heat balance, cirrus clouds, aircraft exhaust, heterogeneous atmospheric chemistry and their interactions with each other. The SUCCESS results will be addressed in a series of Special Sections of Geophysical Research Letters over the next few months. Here we provide an overview of these Special Sections.The Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) was a multi-aircraft field campaign which took place in April and May of 1996, over the Central and Western United States. The goal of SUCCESS was to learn more about Earth's radiative heat balance, cirrus clouds, aircraft exhaust, heterogeneous atmospheric chemistry and their interactions with each other. The SUCCESS results will be addressed in a series of Special Sections of Geophysical Research Letters over the next few months. Here we provide an overview of these Special Sections."
"7202154370;7003309358;57207603330;","The retrieval of cirrus cloud properties from aircraft multi-spectral reflectance measurements during EUCREX'93",1998,"10.1256/smsqj.54811","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031659522&doi=10.1256%2fsmsqj.54811&partnerID=40&md5=5e114604ef240edeecd5e5a651b8be9e","We present details of a scheme for retrieving cirrus cloud optical thickness and effective particle size from nadir-viewing reflectance measurements. Two near-infrared wavelengths are used, one with negligible ice absorption (1.04 μm) and one with significant ice absorption (1.55 μm). Four ice crystal shapes are used in the scheme: ice spheres, hexagonal columns, hexagonal plates and randomized polycrystals. We highlight the sensitivity of the retrievals to the shape of the phase function, which follows from the particular ice crystal shape assumed. Five aircraft-based retrievals are presented, all cases occurring during the 1993 intensive field campaign of the European Cloud Radiation Experiment (EUCREX'93). The retrieved effective sizes are compared with the in situ measurements taken from the same cases. In these comparisons, account has to be taken of the fact that (a) in situ replicator data indicate that the presence of small (<100 μm) ice crystals can have a significant effect on the effective crystal size, and (b) the measured crystal sizes consistently show a systematic decrease with height in all cases, the effective sizes at cloud base being typically two or three times larger than at cloud top. Taking these considerations into account, we conclude that the assumption of polycrystals gives the most consistent agreement with the in situ measurements."
"8581784200;7003608266;7101772062;","Cross-tropopause tracer transport in midlatitude convection",2005,"10.1029/2004JD005059","https://www.scopus.com/inward/record.uri?eid=2-s2.0-20044387648&doi=10.1029%2f2004JD005059&partnerID=40&md5=6606109d897c1d8d49a6f7f3791ebe98","The three-dimensional cloud-resolving model is used to simulate the transport of lower-tropospheric passive tracers into the lowermost stratosphere via midlatitude convection. In previous studies of troposphere-to-stratosphere convective transport the extent of irreversible transport is unclear because the tropopause location is difficult to determine in the highly perturbed environment directly above an active storm. To determine the irreversibility of cross-tropopause transport in this study, 10-hour simulations are carried out to cover the growth and decay cycles of the storm. After the decay of convection, isentropes relax to quasi-flat surfaces, and the position of the tropopause becomes much easier to establish. Air parcels containing boundary layer tracers were able to penetrate the stable stratosphere because diabatic processes increased the parcel's potential temperature sufficiently to make the parcel neutrally buoyant at stratospheric altitudes. The boundary layer tracer was carried upward in the core of the updraft whereas tracers originating from higher levels were lifted on the flanks of the updraft and therefore underwent less transport into the stratosphere. Three different cases were simulated: a prototypical supercell, a prototypical multicell, and a supercell observed during the Severe Thunderstorm Electrification and Precipitation Study (STEPS) field campaign. In the prototypical supercell simulation, at 1 km above the tropopause the maximum concentration of boundary layer tracer is diluted to 26% of its original concentration; the maximum concentration of the tracer originating in the layer between 1 and 4 km is diluted to 23% of its original concentration. Simulation of the STEPS storm showed similar irreversible transport in a less idealized case. Both supercell storms produced more transport than the prototypical multicell storm. Copyright 2005 by the American Geophysical Union."
"7003708056;7005140302;7007053654;7004100461;7004983984;56506988700;7003640784;6603902689;57195355957;7006354036;7005601996;7005198666;35477504600;6507099890;6701336868;6602536259;7006595513;7102496779;7006634316;7005088845;16170561000;7003377899;8870846900;57203079636;7003767429;7004191948;7006235542;7003880283;7005941217;","The Kleiner Feldberg Cloud Experiment 1990. An overview",1994,"10.1007/BF00696581","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028598849&doi=10.1007%2fBF00696581&partnerID=40&md5=b80edcd5e4c25b1ae8656cb0e187fc75","An overview is given of the Kleiner Feldberg cloud experiment performed from 27 October until 13 November 1990. The experiment was carried out by numerous European research groups as a joint effort within the EUROTRAC-GCE project in order to study the interaction of cloud droplets with atmospheric trace constituents. After a description of the observational site and the measurements which were performed, the general cloud formation mechanisms encountered during the experiment are discussed. Special attention is given here to the process of moist adiabatic lifting. Furthermore, an overview is given regarding the pollutant levels in the gas phase, the particulate and the liquid phase, and some major findings are presented with respect to the experimental objectives. Finally, a first comparison attempts to put the results obtained during this campaign into perspective with the previous GCE field campaign in the Po Valley. © 1994 Kluwer Academic Publishers."
"37760934500;16479877100;56018213900;56468356900;55770282000;7004040199;7403384594;6701378450;","On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosols in the southeastern United States",2015,"10.5194/acp-15-8679-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84938796161&doi=10.5194%2facp-15-8679-2015&partnerID=40&md5=e95c012d8963ea8362fe0afd2ee22d0f","The formation of secondary organic aerosols (SOAs) combined with the partitioning of semivolatile organic components can impact numerous aerosol properties including cloud condensation nuclei (CCN) activity, hygroscopicity, and volatility. During the summer 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign in a rural site in the southeastern United States, a suite of instruments including a CCN counter, a thermodenuder (TD), and a high-resolution time-of-flight aerosol mass spectrometer (AMS) were used to measure CCN activity, aerosol volatility, composition, and oxidation state. Particles were either sampled directly from ambient or through a particle-into-liquid sampler (PILS), allowing the investigation of the water-soluble aerosol component. Ambient aerosols exhibited size-dependent composition with larger particles being more hygroscopic. The hygroscopicity of thermally denuded aerosols was similar between ambient and PILS-generated aerosols and showed limited dependence on volatilization. Results of AMS three-factor positive matrix factorization (PMF) analysis for the PILS-generated aerosols showed that the most hygroscopic components are most likely the most and the least volatile features of the aerosols. No clear relationship was found between organic hygroscopicity and the oxygen-to-carbon ratio; in fact, isoprene-derived organic aerosols (isoprene-OAs) were found to be the most hygroscopic factor, while at the same time being the least oxidized and likely most volatile of all PMF factors. Considering the diurnal variation of each PMF factor and its associated hygroscopicity, isoprene-OA and more-oxidized oxygenated organic aerosols are the prime contributors to hygroscopicity and co-vary with less-oxidized oxygenated organic aerosols in a way that induces the observed diurnal invariance in total organic hygroscopicity. Biomass burning organic aerosols contributed little to aerosol hygroscopicity, which is expected since there was little biomass burning activity during the sampling period examined. © Author(s) 2015."
"36054921000;7102567936;7404970050;56086015900;57187656400;56576680000;","Regional simulation of the october and november MJO events observed during the CINDY/DYNAMO field campaign at gray zone resolution",2015,"10.1175/JCLI-D-14-00294.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961292171&doi=10.1175%2fJCLI-D-14-00294.1&partnerID=40&md5=f4de6f3dbf09f092b16c0b0ee9bcf224","This study investigates the October and November MJO events observed during the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY)/Dynamics of the MJO (DYNAMO) field campaign through cloud-permitting numerical simulations. The simulations are compared to multiple observational datasets. The control simulation at 9-km horizontal grid spacing captures the slow eastward progression of both the October and November MJO events in surface precipitation, outgoing longwave radiation, zonal wind, humidity, and large-scale vertical motion. The vertical motion shows weak ascent in the leading edge of the MJO envelope, followed by deep ascent during the peak precipitation stage and trailed by a broad second baroclinic mode structure with ascent in the upper troposphere and descent in the lower troposphere. Both the simulation and the observations also show slow northward propagation components and tropical cyclone-like vortices after the passage of the MJO active phase. Comparison with synthesized observations from the northern sounding array shows that the model simulates the passage of the two MJO events over the sounding array region well. Sensitivity experiments to SST indicate that daily SST plays an important role for the November MJO event, but much less so for the October event. Analysis of the moist static energy (MSE) budget shows that both advection and diabatic processes (i.e., surface fluxes and radiation) contribute to the development of the positive MSE anomaly in the active phase, but their contributions differ by how much they lead the precipitation peak. In comparison to the observational datasets used here, the model simulation may have a stronger surface flux feedback and a weaker radiative feedback. The normalized gross moist stability in the simulations shows an increase from near-zero values to ~0.8 during the active phase, similar to what is found in the observational datasets. © 2015 American Meteorological Society."
"7004854393;6602743662;7003798418;6506539095;16678672300;7003516381;6602344979;","Surface thermodynamics and radiative budget in the Sahelian Gourma: Seasonal and diurnal cycles",2009,"10.1016/j.jhydrol.2008.09.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-69549135788&doi=10.1016%2fj.jhydrol.2008.09.007&partnerID=40&md5=cce1344ad23c085e459f0a1340f28cf4","Our understanding of the role of surface-atmosphere interactions in the West African monsoon has been particularly limited by the scarcity of measurements. The present study provides a quantitative analysis of the very pronounced seasonal and diurnal cycles of surface thermodynamics and radiative fluxes in the Central Sahel. It makes use of data collected from 2002 to 2007 in the Malian Gourma, close to Agoufou, at 1.5°W-15.3°N and sounding data collected during the AMMA field campaign. The seasonal cycle is characterized by a broad maximum of temperature in May, following the first minimum of the solar zenith angle (SZA) by a few weeks, when Agoufou lies within the West African Heat Low, and a late summer maximum of equivalent potential temperature (θe) within the core of the monsoon season, around the second yearly maximum of SZA. Distinct temperature and moisture seasonal and diurnal dynamics lead to a sharpening of the early (late) monsoon increase (decrease), more steadiness of θe and larger changes of relative humidity in between. Rainfall starts after the establishment of the monsoon flow, once temperature already started to decrease slowly, typically during June. Specific humidity increases progressively from May until August, while the monsoon flow weakens during the same period. Surface net radiation (Rnet) increases from around 10-day mean values of 20 W m-2 in Winter to 120-160 W m-2 in late Summer, The increase is sharper during the monsoon than before, and the decrease fast. The seasonal cycle of Rnet arises from distinct shortwave and longwave fluctuations that are both strongly shaped by modifications of surface properties related to rainfall events and vegetation phenology (with a decrease of both surface longwave emission and albedo). During the monsoon, clouds and aerosols reduce the incoming solar radiation by 20-25% (about 70 W m-2). They also significantly enhance the day-to-day variability of Rnet. Nevertheless, the surface incoming longwave radiative flux (LWin) is observed to decrease from June to September. As higher cloud covers and larger precipitable water amounts are typically expected to enhance LWin, this feature points to the significance of changes in atmospheric temperature and aerosols during the monsoon season. The strong dynamics associated with the transition from a drier hot Spring to a brief cooler moist tropical Summer climate involves large transformations of the diurnal cycle, even within the monsoon season, which significantly affect both thermodynamical, dynamical and radiative fields (and low-level dynamics). In particular, for all moist Summer months except August, specific humidity decreases in such a way during daytime that it prevents an afternoon increase of θe. In agreement with some previous studies, strong links are found between moisture and LWnet all year long and a positive correlation is identified between Rnet and θe during the monsoon. The observational results presented in this study further provide valuable ground truth for assessing models over an area displaying a rich variety of surface-atmosphere regimes. © 2008 Elsevier B.V. All rights reserved."
"21935606200;7402866430;9246074500;6701689811;7203075090;6701707185;","Enhanced layer of black carbon in a north Indian industrial city",2005,"10.1029/2005GL022564","https://www.scopus.com/inward/record.uri?eid=2-s2.0-25844510745&doi=10.1029%2f2005GL022564&partnerID=40&md5=4681903ceaee16d26726ae4cc89e4a42","During a comprehensive aerosol field campaign as part of Indian Space Research Organization Geosphere Biosphere Programme (ISRO-GBP), aircraft measurements of vertical profiles of aerosol black carbon (BC) were made during winter, for the first time, at Kanpur (80°20′E and 26°26′N), an urban industrial location in Northern India. Two vertical profiling from the same day (morning and afternoon) of BC showed that BC decreases with height up to ∼600 in and then increases up to 900 m before becoming more or less constant with height. Potential temperature profile, derived from concurrent measurements of temperature, shows a stable layer at the same altitude where BC shows increased concentration. This vertical structure of boundary layer was further confirmed by separate temperature and relative humidity profiles obtained from balloonsondes during December. The increased BC at ∼900 in suggests the presence of enhanced BC layer, which will have significant implications to BC radiative forcing and modifying cloud properties. Copyright 2005 by the American Geophysical Union."
"7003406689;36058918500;7005729142;7004399029;","Microphysical characteristics of tropical updrafts in clean conditions",2004,"10.1175/2104.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3042774905&doi=10.1175%2f2104.1&partnerID=40&md5=318f6dae14ded56113715d6db1176492","The distribution of ice particles, precipitation embryos, and supercooled water are examined within updrafts in convective clouds in the Amazon and at Kwajalein, Marshall Islands based on in situ measurements during two Tropical Rainfall Measuring Mission field campaigns. Composite vertical profiles of liquid water, small particle concentration, and updraft/downdraft magnitudes exhibit similar peak values for the two tropical regions. Updraft were found to be favored locations for precipitation embryos in the form of liquid or frozen drizzle-sized droplets. Most updrafts glaciated rapidly, removing most of the liquid water between - 5° and - 17°C. However, occasional encounters with liquid water occurred in much colder updraft regions. The updraft magnitudes where liquid water was observed at cold (e.g., - 16° to - 19°C) temperatures do not appear to be stronger than updrafts without liquid water at similar temperatures, however. The concentrations of small spherical frozen particles glaciated regions without liquid water are approximately one-half of the concentrations in regions containing liquid cloud droplets, suggesting that a substantial portion of the cloud droplets may be freezing at relatively warm temperatures. Further evidence for a possible new type of aggregate ice particle, a chain aggregate found at cloud midlevels, is given. © 2004 American Meteorological Society."
"7102680152;7006434689;56612704000;7005174340;7004923073;7005069415;","Size-dependent aerosol activation at the high-alpine site Jungfraujoch (3580 m asl)",2002,"10.1034/j.1600-0889.2002.00299.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036171436&doi=10.1034%2fj.1600-0889.2002.00299.x&partnerID=40&md5=14304725d929174a4cb1cc392d84f495","Microphysical and chemical aerosol properties and their influence on cloud formation were studied in a field campaign at the high-alpine site Jungfraujoch (JFJ, 3580 m asl). Due to its altitude, this site is suitable for ground-based in-cloud measurements, with a high cloud frequency of 40%. Dry total and interstitial aerosol size distributions [18 nm &lt; particle diameter (Dp) &lt; 800 nm] were determined with a time resolution of 6 min. A forward scattering spectrometer probe (FSSP-100) measured the cloud droplet size distribution, and a particle volume monitor (PVM-100) was used to measure liquid water content (LWC). In addition, the aerosol chemical composition (major soluble ions) was determined in two size classes (total and submicron particles). Agreement within the range of measurement uncertainties was observed between the droplet number concentrations derived from the aerosol size distribution measurements (total minus interstitial) and those measured by the FSSP. The observed particle diameter at 50% activation (D50) was typically around 100 nm for LWC ≥ 0.15 g m-3. Below this value, D50 increased with decreasing LWC. A dependence of D50 on the accumulation mode (Dp &gt; 100 nm) number concentration (Ntot.Dp&gt;100) was only found for concentrations less than 100 cm-3. For higher values of Ntot.Dp&gt;100 the D50 remained constant. Furthermore, a decrease of the effective radius of cloud droplets (Reff) with increasing Ntot.Dp&gt;100 was observed, providing experimental evidence for the microphysical relation predicted by the Twomey effect. A modified Köhler model was used to quantify the critical supersaturation for the aerosol observed at the JFJ. Ambient supersaturations were determined from the derived supersaturation curve and the calculated D5). As an example, a critical supersaturation of 0.2% was found for 100 nm particles."
"12645126500;6602111828;7004003763;","Precipitation characteristics of trade wind clouds during RICO derived from Radar, Satellite, and aircraft measurements",2009,"10.1175/2008JAMC1946.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67549151314&doi=10.1175%2f2008JAMC1946.1&partnerID=40&md5=0736732092a9926cf39e84f57f50f4b6","Precipitation characteristics of trade wind clouds over the Atlantic Ocean near Barbuda are derived from radar and aircraft data and are compared with satellite-observed cloud fields collected during the Rain in Cumulus over the Ocean (RICO) field campaign. S-band reflectivity measurements Z were converted to rainfall rates R using a Z-R relationship derived from aircraft measurements. Daily rainfall rates varied from 0 to 22 mm day-1. The area-averaged rainfall rate for the 62-day period was 2.37 mm day-1. If corrected for evaporation below cloud base, this value is reduced to 2.23 mm day-1, which translates to a latent heat flux to the atmosphere of 63 W m-2. When compared with the wintertime ocean-surface latent heat flux from this region, the average return of water to the ocean through precipitation processes within the trade wind layer during RICO was 31%-39%. A weak diurnal cycle was observed in the area-averaged rainfall rate. The magnitude of the rainfall and the frequency of its occurrence had a maximum in the predawn hours and a minimum in the midmorning to early afternoon on 64% of the days. Radar data were collocated with data from the Multiangle Imaging Spectroradiometer (MISR) to develop relationships between cloud-top height, cloud fraction, 866-nm bidirectional reflectance factor (BRF), and radar-derived precipitation. The collocation took place at the overpass time of ∼ 1045 local time. These relationships revealed that between 5.5% and 10.5% of the cloudy area had rainfall rates that were &gt; 0.1 mm h-1, and between 1.5% and 3.5% of the cloudy area had rainfall rates that were &gt; 1 mm h-1. Cloud-top heights between ∼ 3 and 4 km and BRFs between 0.4 and 1.0 contributed ∼ 50% of the total rainfall. For cloudy pixels having detectable rain, average rainfall rates increased from ∼ 1 to 4 mm h-1 as cloud-top heights increased from ∼ 1 to 4 km. Rainfall rates were closely tied to the type of mesoscale organization, with much of the rainfall originating from shallow (&lt;5 km) cumulus clusters shaped as arcs associated with cold-pool outflows. © 2009 American Meteorological Society."
"7006962390;6506127919;26027584400;7005421048;6603933557;6603625455;24776869700;26027400100;26027513400;26027587000;57197913710;35551238800;","Multiplatform observations of the seasonal evolution of the Saharan atmospheric boundary layer in Tamanrasset, Algeria, in the framework of the African Monsoon Multidisciplinary Analysis field campaign conducted in 2006",2008,"10.1029/2007JD009417","https://www.scopus.com/inward/record.uri?eid=2-s2.0-59749095381&doi=10.1029%2f2007JD009417&partnerID=40&md5=86749de8712ae5db24ff1471eacdc336","We document the seasonal evolution of the Saharan atmospheric boundary layer (SABL), in terms of vertical structure, diurnal cycle, aerosol content, and cloud cover as well as the surface radiative budget, during 2006, using a mobile multiplatform atmospheric observatory implemented in Tamanrasset (Algeria). Ground-based remote sensing (both active and passive) and in situ instruments were deployed in the framework of the African Monsoon Multidisciplinary Analysis field experiment and were used in synergy with satellite observations. Observations showed a marked seasonal evolution of the SABL characteristics and a large variability during the West African monsoon onset phase. At the beginning of June, hazy conditions prevailed in a deep SABL (∼5 km). Following this, reduced cloud cover induced by anomalous large-scale subsidence resulted in high surface insolation which enhanced the convective development of the SABL (∼6 km deep). During that period, the proximity of the Saharan heat low was also favorable to the SABL deepening. In August and September, humidity advected from the south enhanced cloud cover and limited the SABL vertical development (∼3.8 km deep). In the wintertime, weak dry convection and the Hadley cell-related subsidence resulted in high visibility and an extremely shallow SABL (∼500 m deep). Throughout 2006, the aerosol vertical distribution within the SABL was nonuniform, with the majority of coarse particles being located near the surface. The aerosol content over Tamanrasset was influenced by dust transport from a variety of source regions after being lifted through different mechanisms (low-level jets; cold pools or topographic flows). Copyright 2008 by the American Geophysical Union."
"40761500800;7006198994;","The moist static energy budget in NCAR CAM5 hindcasts during DYNAMO",2014,"10.1002/2013MS000272","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84904861215&doi=10.1002%2f2013MS000272&partnerID=40&md5=10a8f35675e5bcb977036f439c99f044","The Dynamics of the MJO (DYNAMO) field campaign took place in the Indian Ocean during boreal fall and winter of 2011-2012 to collect observations of Madden-Julian Oscillation (MJO) initiation. Hindcast experiments are conducted with an atmospheric general circulation model with varying values of a dilute CAPE entrainment rate parameter for the first two MJO events of DYNAMO from 1 October 2011 to 15 December 2011. Higher entrainment rates better reproduce MJO precipitation and zonal wind, with RMM skill up to 20 days. Simulations with lower entrainment rapidly diverge from observations with no coherent MJO convective signal after 5 days, and no MJO predictive skill beyond 12 days. Analysis of the tropical Indian Ocean column moist static energy (MSE) budget reveals that the simulations with superior MJO performance exhibit a mean positive MSE tendency by vertical advection; inconsistent with reanalysis that indicates a weak negative tendency. All simulations have weaker mean MSE source tendency and significantly weaker cloud-radiative feedbacks. The vertical gross moist stability (VGMS) is used to interpret these MSE budget results in a normalized framework relevant to moisture mode theory. VGMS in the high entrainment runs is far too low compared to ERAi, indicating that it cannot be used in isolation as a measure of model success in producing a realistic MJO hindcast, contrary to previous studies. However, effective VGMS that includes radiative feedbacks is similar among the high entrainment runs and ERAi. We conclude that the MJO is erroneously improved by increasing the entrainment parameter because moistening by vertical MSE advection compensates for the overly weak cloud-radiative feedbacks. Key Points Higher entrainment improves MJO DYNAMO Hindcasts for the wrong reason MSE import by vertical advection compensates for overly weak MSE sources Changes in the omega profile largely explain the differences in GMS among models © 2014. The Authors."
"22954523900;7003414581;57199772022;7003375617;6701697023;7005729142;7003398293;7202057166;","Cirrus optical properties observed with lidar, radiosonde, and satellite over the tropical Indian Ocean during the aerosol-polluted northeast and clean maritime southwest monsoon",2007,"10.1029/2006JD008352","https://www.scopus.com/inward/record.uri?eid=2-s2.0-35748950139&doi=10.1029%2f2006JD008352&partnerID=40&md5=1330b89affa831d43b54682ca3f2c3b4","Cirrus formation and geometrical and optical properties of tropical cirrus as a function of height and temperature are studied on the basis of INDOEX (Indian Ocean Experiment) lidar and radiosonde measurements and satellite observations of deep convection causing the generation of anvil cirrus. Lidar and radiosonde measurements were conducted at Hulule (4.1°N, 73°E), Maldives, during four field campaigns carried out in February-March 1999 and March 2000 (northeast (NE) monsoon season, characterized by increased concentrations of anthropogenic aerosols over the Indian Ocean) and in July and October 1999 (southwest (SW) monsoon season, characterized by clean maritime conditions). As a result of a stronger impact of deep convection on cirrus formation during the SW monsoon season, cirrus clouds covered the sky over the lidar site in only 35% (NE), but 64% (SW) of the measurement time. Subvisible cirrus (optical depth ≤0.03), thin (optical depth from 0.03 to 0.3), and opaque cirrus (optical depth ≥03) were observed in 18%, 48%, and 34% (NE) and in 8%, 52%, and 40% (SW) out of all cirrus cases, respectively. Mean midcloud heights were rather similar with values of 12.9 ± 1.5 km (NE) and 12.7 ± 1.3 km (SW). In 25% of the cases the cirrus top height was found close to the tropopause. Mean values of the multiple-scattering-corrected cirrus optical depth, cirrus layer mean extinction coefficient, and extinction-to-backscatter ratio were 0.25 ± 0.26 (NE) and 0.34 ± 0.29 (SW), 0.12 ± 0.09 km-1 (NE) and 0. 12 ± 0. 10 km-1 (SW), and 33 ± 9 sr (NE) and 29 ± 11 sr (SW), respectively. A functional dependency of the extinction coefficient of the tropical cirrus on temperature is presented. All findings are compared with several other cirrus lidar observations in the tropics, subtropics, and at midlatitudes. By contrasting the cirrus optical properties of the different seasons, a potential impact of anthropogenic particles on anvil cirrus optical properties was examined. Differences in the cirrus extinction-to-backscatter ratio suggest that NE monsoon anvil cirrus originating from deep-convection cumulus clouds had more irregularly shaped and thus slightly larger ice crystals than respective SW monsoon anvil cirrus. Because the meteorological conditions were found to vary significantly between the seasons, an unambiguous identification of the influence of Asian haze on cirrus optical properties is not possible. Copyright 2007 by the American Geophysical Union."
"7102000442;55745955800;7004369046;","Heating structures of the TRMM field campaigns",2007,"10.1175/JAS3938.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547739988&doi=10.1175%2fJAS3938.1&partnerID=40&md5=5bf4c8a5530bd564b611647b8b7b598d","Heating profiles calculated from sounding networks and other observations during three Tropical Rainfall Measuring Mission (TRMM) field campaigns [the Kwajalein Experiment (KWAJEX), TRMM Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), and South China Sea Monsoon Experiment (SCSMEX)] show distinct geographical differences between oceanic, continental, and monsoon regimes. Differing cloud types (both precipitating and nonprecipitating) play an important role in determining the total diabatic heating profile. Variations in the vertical structure of the apparent heat source, Q1, can be related to the diurnal cycle, large-scale forcings such as atmospheric waves, and rain thresholds at each location. For example, TRMM-LBA, which occurred in the Brazilian Amazon, had mostly deep convection during the day while KWAJEX, which occurred in the western portion of the Pacific intertropical convergence zone, had more shallow and moderately deep daytime convection. Therefore, the afternoon height of maximum heating was more bottom heavy (i.e., heating below 600 hPa) during KWAJEX compared to TRMM-LBA. More organized convective systems with extensive stratiform rain areas and upper-level cloud decks tended to occur in the early and late morning hours during TRMM-LBA and KWAJEX, respectively, thereby causing Q1 profiles to be top heavy (i.e., maxima from 600 to 400 hPa) at those times. SCSMEX, which occurred in the South China Sea during the monsoon season, had top-heavy daytime and nighttime heating profiles suggesting that mesoscale convective systems occurred throughout the diurnal cycle, although more precipitation and upper-level cloud in the afternoon caused the daytime heating maximum to be larger. A tendency toward bottom- and top-heavy heating profile variations is also associated with the different cloud types that occurred before and after the passage of easterly wave troughs during KWAJEX, the easterly and westerly regimes during TRMM-LBA, and the monsoon onset and postonset active periods during SCSMEX. Rain thresholds based on heavy, moderate, and light/no-rain amounts can further differentiate top-heavy heating, bottom-heavy heating, and tropospheric cooling. These budget studies suggest that model calculations and satellite retrievals of Q1 must account for a large number of factors in order to accurately determine the vertical structure of diabatic heating associated with tropical cloud systems. © 2007 American Meteorological Society."
"57201177267;6603137309;13408501200;7004436916;57205497429;","River breeze circulation in eastern Amazonia: Observations and modelling results",2004,"10.1007/s00704-004-0047-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2642587087&doi=10.1007%2fs00704-004-0047-6&partnerID=40&md5=1aeb156ba5953cc5061df69dcd29c4b8","The CIRSAN/LBA field campaign was conducted close to two major rivers of the Amazon Basin, the Tapajós and the Amazon. The observations indicate that during weak trade wind episodes the Tapajós River breeze actually induces a westerly flow at the eastern margin with an associated line of shallow cumulus. The atmospheric circulation induced by the river has been interpreted with the help of a high resolution numerical simulation. A single cell forms during late morning over the Tapajós River and evolves into the afternoon with ascending motion in the eastern margin and a descending branch in the western margin suppressing cloud formation. During the night, convergence is seen along the centre of the River Tapajós. The implications of the particular geometry of the river with respect to the trade winds for the generalization of the surface measurements of turbulent fluxes of heat, moisture and CO2 in the Tapajós eastern margin of the Amazon Basin as a whole are discussed. © Springer-Verlag 2004."
"7003390361;7404187535;6603547710;22949331500;7005052721;35838666300;","Urban-rural contrasts in mixing height and cloudiness over Nashville in 1999",2003,"10.1029/2001jd001061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141935012&doi=10.1029%2f2001jd001061&partnerID=40&md5=14f3c355d0f223d35c913965ce8a9e67","Strong contrasts in daytime mixing height (boundary layer [BL] height or zi) between urban and rural areas were observed during the 1999 Nashville Summer Intensive field campaign of the Southern Oxidants Study. On occasion, the urban mixing height was as much as 45% (700 m) higher than that over the rural areas. The difference was quite persistent, showing strongly in statistical comparisons, with a mean difference over all hours available for comparison of 160 m. Clouds had higher bases and were more common over the urban area as well. In this paper, measurements from wind profiling radars, lidars, and aircraft are used to characterize mixing height and clouds. The urban-rural contrasts have important implications for regional air quality. The mixing height is a first-order control on pollutant concentrations. The urban-rural contrast also results in the venting of urban pollutants, affecting the local concentrations and the regional background. Clouds affect air quality by changing the radiative input for photochemistry and through changes in mixing and venting."
"6701469150;6701806265;7007172861;7103289129;55619308081;7005052721;","NCAR-NOAA Lower-Tropospheric Water Vapor Workshop",1999,"10.1175/1520-0477(1999)080<2339:NNLTWV>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000827472&doi=10.1175%2f1520-0477%281999%29080%3c2339%3aNNLTWV%3e2.0.CO%3b2&partnerID=40&md5=87c38ebbc09684728a1e08c114bd5f55","A workshop on remote sensing of lower-tropospheric water vapor, jointly sponsored by the National Center for Atmospheric Research (NCAR) and the National Oceanic and Atmospheric Administration, was held on 30 June and 1 July 1998 at NCAR in Boulder, Colorado. Scientists representing a vmety of disciplines, from climate to weather forecasting, presented their needs for improved water vapor measurements. Engineers and scientists gave information on the current technology for water vapor measuring platforms and retrieval methods. The workshop concluded with an open forum at which the participants agreed upon a general recommendation supporting the use, improvement, and development of active and passive remote sensing techniques to obtain three-dimensional fields of water vapor and their evolution. In addition, several specific recommendations were adopted, including the organization of field campaigns for cross validation of measurement techniques, the focus of attention to improve water vapor measurements in and near clouds, and increased collaboration wilhin the community to build, operate, and provide access to airborne and ground-based water vapor remote measuring systems."
"6603484562;7101819382;57216049554;","The field campaigns of the European tracer experiment (ETEX): Overview and results",1998,"10.1016/S1352-2310(98)00190-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032401764&doi=10.1016%2fS1352-2310%2898%2900190-3&partnerID=40&md5=77e581b69f17a22b7f57c9714b307866","As part of the European Tracer Experiment (ETEX) two successful atmospheric experiments were carried out in October and November, 1994. Perfluorocarbon (PFC) tracers were released into the atmosphere in Monterfil, Brittany, and air samples were taken at 168 stations in 17 European countries for 72 h after the release. Upper air tracer measurements were made from three aircraft. During the first experiment a westerly air flow transported the tracer plume north-eastwards across Europe. During the second release the flow was eastwards. The results from the ground sampling network allowed the determination of the cloud evolution as far as Sweden, Poland and Bulgaria. This demonstrated that the PFT technique can be successfully applied in long-range tracer experiments up to 2000 km. Typical background concentrations of the tracer used are around 5-7 fl l-1 in ambient air. Concentrations in the plume ranged from 10 to above 200 fl/l-1. The tracer release characteristics, the tracer concentrations at the ground and in upper air, the routine and additional meteorological observations at the ground level and in upper air, trajectories derived from constant-level balloons and the meteorological input fields for long-range transport models are assembled in the ETEX database. The ETEX database is accessible via the Internet. Here, an overview is given of the design of the experiment, the methods used and the data obtained.As part of the European Tracer Experiment (ETEX) two successful atmospheric experiments were carried out in October and November, 1994. Perfluorocarbon (PFC) tracers were released into the atmosphere in Monterfil, Brittany, and air samples were taken at 168 stations in 17 European countries for 72 h after the release. Upper air tracer measurements were made from three aircraft. During the first experiment a westerly air flow transported the tracer plume north-eastwards across Europe. During the second release the flow was eastwards. The results from the ground sampling network allowed the determination of the cloud evolution as far as Sweden, Poland and Bulgaria. This demonstrated that the PFT technique can be successfully applied in long- range tracer experiments up to 2000 km. Typical background concentrations of the tracer used are around 5-7 fl l-1 in ambient air. Concentrations in the plume ranged from 10 to above 200 fl/l-1. The tracer release characteristics, the tracer concentrations at the ground and in upper air, the routine and additional meteorological observations at the ground level and in upper air, trajectories derived from constant-level balloons and the meteorological input fields for long-range transport models are assembled in the ETEX database. The ETEX database is accessible via the Internet. Here, an overview is given of the design of the experiment, the methods used and the data obtained."
"57209089003;22136950500;57212901405;8963601100;23098283400;57188735205;57009108900;57188744437;24458137900;","Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: High acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley",2016,"10.5194/acp-16-3979-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962740169&doi=10.5194%2facp-16-3979-2016&partnerID=40&md5=99e875f81609acd0befd3674a750bbeb","The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012-2013, a comprehensive study was carried out to characterise the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs, by deploying a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) &amp;ndash; the first such deployment in South Asia. In the study, 71 ion peaks (for which measured ambient concentrations exceeded the 2σ detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m/Δm &gt; 4200) and temporal resolution (1 min) of the PTR-TOF-MS. The concentration ranking in the average VOC mixing ratios during our wintertime deployment was acetaldehyde (8.8 ppb) &amp;gt; methanol (7.4 ppb) &amp;gt; acetone + propanal (4.2 ppb) &amp;gt; benzene (2.7 ppb) &amp;gt; toluene (1.5 ppb) &amp;gt; isoprene (1.1 ppb) &amp;gt; acetonitrile (1.1 ppb) &amp;gt; C8-aromatics ( ĝ1/4 1 ppb) &amp;gt; furan ( ĝ1/4 0.5 ppb) &gt; C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m/z=69.070) and furan (m/z=69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde (∼9 ppb), acetonitrile (∼1 ppb) and isoprene (∼1 ppb) to be among the highest reported to date. Two ""new"" ambient compounds, namely formamide (m/z=46.029) and acetamide (m/z=60.051), which can photochemically produce isocyanic acid in the atmosphere, are reported in this study along with nitromethane (a tracer for diesel exhaust), which has only recently been detected in ambient studies. Two distinct periods were selected during the campaign for detailed analysis: the first was associated with high wintertime emissions of biogenic isoprene and the second with elevated levels of ambient acetonitrile, benzene and isocyanic acid from biomass burning activities. Emissions from biomass burning and biomass co-fired brick kilns were found to be the dominant sources for compounds such as propyne, propene, benzene and propanenitrile, which correlated strongly with acetonitrile (r2 &gt; 0.7), a chemical tracer for biomass burning. The calculated total VOC OH reactivity was dominated by acetaldehyde (24.0 %), isoprene (20.2 %) and propene (18.7 %), while oxygenated VOCs and isoprene collectively contributed to more than 68 % of the total ozone production potential. Based on known secondary organic aerosol (SOA) yields and measured ambient concentrations in the Kathmandu Valley, the relative SOA production potential of VOCs were benzene &gt; naphthalene &gt; toluene &gt; xylenes &gt; monoterpenes &gt; trimethylbenzenes &gt; styrene &gt; isoprene. The first ambient measurements from any site in South Asia of compounds with significant health effects such as isocyanic acid, formamide, acetamide, naphthalene and nitromethane have been reported in this study. Our results suggest that mitigation of intense wintertime biomass burning activities, in particular point sources such biomass co-fired brick kilns, would be important to reduce the emission and formation of toxic VOCs (such as benzene and isocyanic acid) in the Kathmandu Valley. © Author(s) 2016. CC Attribution 3.0 License."
"8391023000;56850959100;6603785669;35768200800;","Reconciling float-based and tracer-based estimates of lateral diffusivities",2012,"10.1357/002224012805262743","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84868133597&doi=10.1357%2f002224012805262743&partnerID=40&md5=88e5e4771034dac2e30fd4bed92e2792","Lateral diffusivities are computed from synthetic particles and tracers advected by a velocity field derived from sea-surface height measurements from the South Pacific, in a region west of Drake Passage. Three different estimates are compared: (1) the tracer-based ""effective diffusivity"" of Nakamura (1996), (2) the growth of the second moment of a cloud of tracer and (3) the single- and two-particle Lagrangian diffusivities. The effective diffusivity measures the cross-stream component of eddy mixing, so this article focuses on the meridional diffusivities for the others, as the mean flow (the ACC) is zonally oriented in the region. After an initial transient of a few weeks, the effective diffusivity agrees well with the meridional diffusivity estimated both from the tracer cloud and from the particles. This proves that particleand tracer-based estimates of eddy diffusivities are equivalent, despite recent claims to the contrary. Convergence among the three estimates requires that the Lagrangian diffusivities be estimated using their asymptotic values, not their maximum values. The former are generally much lower than the latter in the presence of a mean flow. Sampling the long-time asymptotic behavior of Lagrangian diffusivities requires very large numbers of floats in field campaigns. For example, it is shown that hundreds of floats would be necessary to estimate the vertical and horizontal variations in eddy diffusivity in a sector of the Pacific Southern Ocean."
"7405489798;6506328135;","Bi-modal structure and variability of large-scale diabatic heating in the tropics",2009,"10.1175/2009JAS3089.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949422454&doi=10.1175%2f2009JAS3089.1&partnerID=40&md5=79a30ee324c7005824143e382929efe6","Tropical diabatic heating profiles estimated using sounding data from eight field campaigns were diagnosed to document their common and prevailing structure and variability that are relevant to the large-scale circulation. The first two modes of a rotated empirical orthogonal function analysis-one deep, one shallow-explain 85% of the total variance of all data combined. These two modes were used to describe the heating evolution, which led to three composited heating profiles that are considered as prevailing large-scale heating structures. They are, respectively, shallow, bottom heavy (peak near 700 hPa); deep, middle heavy (peak near 400 hPa); and stratiform-like, top heavy (heating peak near 400 hPa and cooling peak near 700 hPa). The amplitudes and occurrence frequencies of the shallow, bottom-heavy heating profiles are comparable to those of the stratiform-like, top-heavy ones. The sequence of the most probable heating evolution is deep tropospheric cooling to bottom-heavy heating, to middle heavy heating, to stratiform-like heating, then back to deep tropospheric cooling. This heating transition appears to occur on different time scales. Each of the prevailing heating structures is interpreted as being composed of particular fractional populations of various types of precipitating cloud systems, which are viewed as the building blocks for the mean. A linear balanced model forced by the three prevailing heating profiles produces rich vertical structures in the circulation with multiple overturning cells, whose corresponding moisture convergence and surface wind fields are very sensitive to the heating structures. © 2009 American Meteorological Society."
"56679340600;35122705200;35393786200;7003440950;55743290300;","Radiation-transfer modeling of snow-pack photochemical processes during ALERT 2000",2002,"10.1016/S1352-2310(02)00124-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036017471&doi=10.1016%2fS1352-2310%2802%2900124-3&partnerID=40&md5=d348b769574c2fe2db06ecb93d64b8c9","The delta-Eddington radiation transfer model is used to calculate actinic fluxes and photolysis rates within the snow pack during the ALERT 2000 field campaign. Actinic fluxes are enhanced within the snow pack due to the high albedo of snow and conversion of direct light to diffuse light. The conversion of direct to diffuse light is highly dependent on the solar zenith angle, as demonstrated by model calculations. The optical properties of Alert snow are modeled as 100μm radius ice spheres with impurity added to increase the absorption coefficient over that of pure water ice. Using these optical properties, the model achieves good agreement with observations of irradiance within the snow pack. The model is used to calculate the total actinic flux as a function of solar zenith angle and depth for either clear sky or cloudy conditions. The actinic flux is then used to calculate photochemical production of nitrogen oxides from nitrate photolysis assuming that nitrate in snow has the same absorption cross section and quantum yield in snow as in aqueous solution. Assuming all photo-produced nitrogen oxides are released to the gas phase, we derive a maximal flux of nitrogen oxides (NOx+HONO and possibly other products) from the snow pack. The value of this maximal flux depends critically on the assumed quantum yield for production of NO2, which is unknown in ice. Depending on the assumed quantum yield, the calculated maximal flux varies between values four times smaller than the observed NOx+HONO flux to five times larger than the NOx+HONO flux. Therefore, it appears that the calculated flux is in approximate agreement with the observations with a great need for improved understanding of nitrogen photochemistry in snow. © 2002 Elsevier Science Ltd. All rights reserved."
"7004556087;35477504600;6602238735;15734577800;6601942466;15735037500;22952188100;7005893321;","Black carbon (BC) in alpine aerosols and cloud water - Concentrations and scavenging efficiencies",2001,"10.1016/S1352-2310(01)00312-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034848873&doi=10.1016%2fS1352-2310%2801%2900312-0&partnerID=40&md5=76596cf65e680303d00d998bb0a386f4","During April 1999 and March 2000, intensive field campaigns were performed on a mid-level mountain (Rax, 1644 m a.s.l.) in Central Europe both under out-of-cloud and in-cloud conditions. The black carbon (BC) content of both aerosol and cloud water as well as BC scavenging efficiencies of Rax clouds were measured. As a tracer for the non-carbonaceous aerosol, sulfate was used. Although BC concentrations on Rax were low (April 1999 out-of-cloud average: 0.43 μg/m3, March 2000: 0.72 μg/m3), the BC mass fraction of the aerosol was fairly high (1999: 3.5%, 2000: 6.4%). Average BC concentrations in cloud water were 1.09 μg/ml (1999) and 1.4 μg/ml (2000). These values are far higher than literature values, but comparable to those found in an earlier study (J. Geophys. Res. 105 (D20) (2000) 24637) at a high-level mountain (Sonnblick, 3106 m a.s.l.) some 200 km distant from Rax. The average BC scavenging efficiency of the Rax clouds in March 2000 was 0.54. The increase of scavenging efficiency with increasing liquid water content of the clouds found earlier on Sonnblick for sulfate and aerosol carbon (J. Atmos. Chem 35 (2000) 33), organic carbon (J. Geophys. Res. 105 (2000) 19857), and BC (J. Geophys. Res. 105 (D20) (2000) 24637) was also confirmed on Rax. © 2001 Elsevier Science Ltd. All rights reserved."
"7006423931;","A cirrus-cloud experiment: intensive field observations planned for FIRE.",1987,"10.1175/1520-0477(1987)068<0119:ACCEIF>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0023504070&doi=10.1175%2f1520-0477%281987%29068%3c0119%3aACCEIF%3e2.0.CO%3b2&partnerID=40&md5=8ed87c2aff9a4347f51404a44398af25","The Cirrus Intensive Field Observations is a major component of the First International Satellite Cloud Climatology Project Regional Experiment (FIRE). The field campaign was conducted in Wisconsin during Octover 1986. Observing systems include satellites, 'cloud' lidars, a very high-altitude, satellite-simulator aircraft platform, 2 research aircraft instrumented for detailed in situ microphysical and radiometric observations, a Doppler lidar, numerous passive surface-radiation sites, and a rawinsonde network. This is the first cirrus experiment involving such a comprehensive observing system.-from Author"
"15755995900;7006705919;57193213111;7006270084;8922308700;55717074000;7003666669;55544607500;","Assessing the CAM5 physics suite in the WRF-Chem model: Implementation, resolution sensitivity, and a first evaluation for a regional case study",2014,"10.5194/gmd-7-755-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84900454585&doi=10.5194%2fgmd-7-755-2014&partnerID=40&md5=d18429ea581589e4b1d825e873ccc3a2","A suite of physical parameterizations (deep and shallow convection, turbulent boundary layer, aerosols, cloud microphysics, and cloud fraction) from the global climate model Community Atmosphere Model version 5.1 (CAM5) has been implemented in the regional model Weather Research and Forecasting with chemistry (WRF-Chem). A downscaling modeling framework with consistent physics has also been established in which both global and regional simulations use the same emissions and surface fluxes. The WRF-Chem model with the CAM5 physics suite is run at multiple horizontal resolutions over a domain encompassing the northern Pacific Ocean, northeast Asia, and northwest North America for April 2008 when the ARCTAS, ARCPAC, and ISDAC field campaigns took place. These simulations are evaluated against field campaign measurements, satellite retrievals, and ground-based observations, and are compared with simulations that use a set of common WRF-Chem parameterizations. This manuscript describes the implementation of the CAM5 physics suite in WRF-Chem, provides an overview of the modeling framework and an initial evaluation of the simulated meteorology, clouds, and aerosols, and quantifies the resolution dependence of the cloud and aerosol parameterizations. We demonstrate that some of the CAM5 biases, such as high estimates of cloud susceptibility to aerosols and the underestimation of aerosol concentrations in the Arctic, can be reduced simply by increasing horizontal resolution. We also show that the CAM5 physics suite performs similarly to a set of parameterizations commonly used in WRF-Chem, but produces higher ice and liquid water condensate amounts and near-surface black carbon concentration. Further evaluations that use other mesoscale model parameterizations and perform other case studies are needed to infer whether one parameterization consistently produces results more consistent with observations. © Author(s) 2014. CC Attribution 3.0 License."
"36867020600;8740849900;55709420600;35239166400;55673576800;55450429100;48161789100;57198461801;35975306400;57131535300;57207038794;6603580448;7101799663;","Aqueous phase sulfate production in clouds in eastern China",2012,"10.1016/j.atmosenv.2012.07.079","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84866647227&doi=10.1016%2fj.atmosenv.2012.07.079&partnerID=40&md5=27140adfe302b88c45ddc25dcb8cf0b5","Clouds play an important role in the oxidation of sulfur dioxide to sulfate, since aqueous phase sulfur dioxide oxidation is typically much faster than oxidation in the gas phase. Important aqueous phase oxidants include hydrogen peroxide, ozone and oxygen (catalyzed by trace metals). Because quantities of emitted sulfur dioxide in China are so large, however, it is possible that they exceed the capacity of regional clouds for sulfate production, leading to enhanced long-range transport of emitted SO2 and its oxidation product, sulfate. In order to assess the ability of regional clouds to support aqueous sulfur oxidation, four field campaigns were conducted in 2007 and 2008 at Mt. Tai in eastern China. Single and 2-stage Caltech Active Strand Cloudwater Collectors were used to collect bulk and drop size-resolved cloudwater samples, respectively. Key species that determine aqueous phase sulfur oxidation were analyzed, including cloudwater pH, S(IV), H2O2, Fe, and Mn. Gas phase SO2, O3, and H2O2 were also measured continuously during the campaigns. A wide range of cloud pH values was observed, from 2.6 to 7.6; 60% of cloud samples had a pH between 3 and 5. H2O2 was found to be an important sulfur oxidant, especially at cloudwater pH lower than 5. H2O2 was the most important oxidant in 68% of the cloud sampling periods. High concentrations of residual H2O2 were observed in many periods, especially in summer, implying a substantial capacity for additional sulfur oxidation. O3 was an important oxidant when cloudwater pH was higher than approximately 5-5.3, and was the most important oxidant in 20% of the studied periods. Aqueous sulfur oxidation by O2 (catalyzed by Fe and Mn) was found to be the fastest sulfate production pathway in 12% of the cases. Observed chemical heterogeneity among cloud drop populations was found to enhance rates of S(IV) oxidation by ozone and enhance or slow metal-catalyzed S(IV) autooxidation rates in some periods. These effects were found to be only of minor importance for the total S(IV) oxidation rate, however, as H2O2 was the dominant S(IV) oxidant during most periods. © 2012 Elsevier Ltd."
"6603753015;25629654200;7202252296;","Coatings and clusters of carboxylic acids in carbon-containing atmospheric particles from spectromicroscopy and their implications for cloud-nucleating and optical properties",2010,"10.1029/2009JD012622","https://www.scopus.com/inward/record.uri?eid=2-s2.0-76249087642&doi=10.1029%2f2009JD012622&partnerID=40&md5=9cdd9897637355d26ce8c90b37990aa5","Particle shape and distribution of chemical compounds within individual particles are implied in the parameterizations used in air quality and climate models for radiative transfer, volatility, and mass transfer. In this study we employ Scanning Transmission X-Ray Microscopy with Near-Edge X-Ray Absorption Fine Structure Spectroscopy with image analysis and pattern recognition techniques to characterize the chemical structure of 636 particles collected on six field campaigns in the western hemisphere between 2004 and 2008. Many of the particles were chemically heterogeneous. A few observed types include black carbon particles covered by aqueous-phase components (n = 90), dust particles with organic clumps (106), organic particles enriched in carboxylic acid at the surface (54), and inorganic cores encapsulated by organic shells (10). The 90 particles in the first category collectively contained 95 regions showing a strong black-carbon spectral signature associated with the aqueous-phase components, of which 78 were between 0.1 and 1 μm. Organic mass fraction of the organic dust particles varied significantly (mean and standard deviation of 0.3 ±0.2), and over half of these dust particles were found to be nearly spherical. Thickness of acid-enriched coatings and carbon on inorganic cores were less than 0.6 μm in most cases, but accounted for <0.01 to 0.98 of the particle volume fraction. More than half of the identified organic particles (359) were found to be chemically heterogeneous, and 32 particles were observed as agglomerations or inclusions but did not meet one or more of the criteria of the categories described here. The acidic coatings on black carbon are calculated to have a significant impact on the critical supersaturation of these particles. The measured distribution of aspect ratios of dust and other particles in our samples ranged nonuniformly between 1.0 and 4.6 with a mean of 1.4, which can affect assessment of extinction-to-backscatter ratios over the case where spherical geometry is assumed. Copyright 2010 by the American Geophysical Union."
"24341315100;16308514000;55438848700;7006572336;57196499374;","Aerosol hygroscopicity in the marine atmosphere: A closure study using high-time-resolution, multiple-RH DASH-SP and size-resolved C-ToF-AMS data",2009,"10.5194/acp-9-2543-2009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-73449128448&doi=10.5194%2facp-9-2543-2009&partnerID=40&md5=d2463089ba7c68eef823ca0dcfd115a7","We have conducted the first airborne hygroscopic growth closure study to utilize data from an Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (C-ToF-AMS) coupled with size-resolved, multiple-RH, high-time-resolution hygroscopic growth factor (GF) measurements from the differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP). These data were collected off the coast of Central California during seven of the 16 flights carried out during the MASE-II field campaign in July 2007. Two of the seven flights were conducted in airmasses characterized by continental origin. These flights exhibited elevated organic volume fractions (VForganic=0.56±0. 19, as opposed to 0.39±0.20 for all other flights), corresponding to significantly suppressed GFs at high RH (1.61±0.14 at 92% RH, as compared with 1.91±0.07 for all other flights), more moderate GF suppression at intermediate RH (1.53±0.10 at 85%, compared with 1.58±0.08 for all other flights), and no measurable GF suppression at low RH (1.31±0.06 at 74%, compared with 1.31±0.07 for all other flights). Organic loadings were slightly elevated in above-cloud aerosols, as compared with below-cloud aerosols, and corresponded to a similar trend of significantly suppressed GF at high RH, but more moderate impacts at lower values of RH. A hygroscopic closure based on a volume-weighted mixing rule provided good agreement with DASH-SP measurements (R2=0.78). Minimization of root mean square error between observations and predictions indicated mission-averaged organic GFs of 1.22, 1.45, and 1.48 at 74, 85, and 92% RH, respectively. These values agree with previously reported values for water-soluble organics such as dicarboxylic and multifunctional acids, and correspond to a highly oxidized, presumably water-soluble, organic fraction (mission-averaged O:C=0.92±0.33). Finally, a backward stepwise linear regression revealed that, other than RH, the most important predictor for GF is Vívanlo indicating that a simple emperical model relating GF, RH, and the relative abundance of organic material can provide accurate predictions (R2=0.77) of hygroscopic growth for the California coast."
"7403931916;7003854810;7402516470;6603685334;7201826462;7407116104;7003289221;6603631763;7005002831;","Spectral signature of ice clouds in the far-infrared region: Single-scattering calculations and radiative sensitivity study",2003,"10.1029/2002jd003291","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1342289434&doi=10.1029%2f2002jd003291&partnerID=40&md5=7e62f881aa1438f49120b782a4217b4d","We investigate the spectral signature of ice clouds in the far-infrared (far-IR) spectral region from 100 to 667 cm-1 (15-100 μm). Individual particle scattering properties (extinction efficiency, absorption efficiency, and the asymmetry factor of the scattering phase function) are calculated for small particles using circular cylinders and for large crystals using hexagonal columns. The scattering properties are computed for particle sizes over a size range from 1 to 10,000 μm in maximum dimension from a combination of the T-matrix method, the Lorenz-Mie theory, and an improved geometric optics method. Bulk scattering properties are derived subsequently for 30 particle size distributions, with effective particle sizes ranging from 15 to 150 μm, obtained from various field campaigns for midlatitude and tropical cirrus clouds. Furthermore, a parameterization of the bulk scattering properties is developed. The radiative properties of ice clouds and the clear-sky optical thickness computed from the line-by-line method are input to a radiative transfer model to simulate the upwelling spectral radiance in the far-IR spectral region at the research aircraft height (20 km). On the basis of the simulations, we investigate the sensitivity of far-IR spectra to ice cloud optical thickness and effective particle size. The brightness temperature difference (BTD) between 250 and 559.5 cm-1 is shown to be sensitive to optical thickness for optically thin clouds (visible optical thickness τ &lt; 2). At the other extreme, for optically thick ice clouds (τ &gt; 8), the BTD between 250 and 410.2 cm-1 is shown to be sensitive to the effective particle size up to a limit of 100 μm. © 2003 by the American Geophysical Union."
"55993283100;22234792700;55336364300;55227686000;56489758400;","Snow depth retrieval with UAS using photogrammetric techniques",2015,"10.3390/geosciences5030264","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84941199750&doi=10.3390%2fgeosciences5030264&partnerID=40&md5=908dd6c4e6bce1cd54fd1d91d610b572","Alpine areas pose challenges for many existing remote sensing methods for snow depth retrieval, thus leading to uncertainty in water forecasting and budgeting. Herein, we present the results of a field campaign conducted in Tasmania, Australia in 2013 from which estimates of snow depth were derived using a low-cost photogrammetric approach on-board a micro unmanned aircraft system (UAS). Using commercial off-the-shelf (COTS) sensors mounted on a multi-rotor UAS and photogrammetric image processing techniques, the results demonstrate that snow depth can be accurately retrieved by differencing two surface models corresponding to the snow-free and snow-covered scenes, respectively. In addition to accurate snow depth retrieval, we show that high-resolution (50 cm) spatially continuous snow depth maps can be created using this methodology. Two types of photogrammetric bundle adjustment (BA) routines are implemented in this study to determine the optimal estimates of sensor position and orientation, in addition to 3D scene information; conventional BA (which relies on measured ground control points) and direct BA (which does not require ground control points). Error sources that affect the accuracy of the BA and subsequent snow depth reconstruction are discussed. The results indicate the UAS is capable of providing high-resolution and high-accuracy (<10 cm) estimates of snow depth over a small alpine area (~0.7 ha) with significant snow accumulation (depths greater than one meter) at a fraction of the cost of full-size aerial survey approaches. The RMSE of estimated snow depths using the conventional BA approach is 9.6 cm, whereas the direct BA is characterized by larger error, with an RMSE of 18.4 cm. If a simple affine transformation is applied to the point cloud derived from the direct BA, the overall RMSE is reduced to 8.8 cm RMSE. © 2015 the authors; licensee MDPI, Basel, Switzerland."
"55911904900;57126848900;6602137800;7201966094;7006107059;","Simultaneous retrieval of aerosol and cloud properties during the MILAGRO field campaign",2011,"10.5194/acp-11-6245-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960159467&doi=10.5194%2facp-11-6245-2011&partnerID=40&md5=19b9ad6eea3db2a46404cfb98ae1426b","Estimation of Direct Climate Forcing (DCF) due to aerosols in cloudy areas has historically been a difficult task, mainly because of a lack of appropriate measurements. Recently, passive remote sensing instruments have been developed that have the potential to retrieve both cloud and aerosol properties using polarimetric, multiple view angle, and multi spectral observations, and therefore determine DCF from aerosols above clouds. One such instrument is the Research Scanning Polarimeter (RSP), an airborne prototype of a sensor on the NASA Glory satellite, which unfortunately failed to reach orbit during its launch in March of 2011. In the spring of 2006, the RSP was deployed on an aircraft based in Veracruz, Mexico, as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. On 13 March, the RSP over flew an aerosol layer lofted above a low altitude marine stratocumulus cloud close to shore in the Gulf of Mexico. We investigate the feasibility of retrieving aerosol properties over clouds using these data. Our approach is to first determine cloud droplet size distribution using the angular location of the cloud bow and other features in the polarized reflectance. The selected cloud was then used in a multiple scattering radiative transfer model optimization to determine the aerosol optical properties and fine tune the cloud size distribution. In this scene, we were able to retrieve aerosol optical depth, the fine mode aerosol size distribution parameters and the cloud droplet size distribution parameters to a degree of accuracy required for climate modeling. This required assumptions about the aerosol vertical distribution and the optical properties of the coarse aerosol size mode. A sensitivity study was also performed to place this study in the context of future systematic scanning polarimeter observations, which found that the aerosol complex refractive index can also be observed accurately if the aerosol optical depth is larger than roughly 0.8 at a wavelength of (0.555 μm). © 2011 Author(s)."
"12799209700;7005773698;","Hydroxymethanesulfonate as a tracer for fog processing of individual aerosol particles",2003,"10.1016/S1352-2310(02)01029-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037332457&doi=10.1016%2fS1352-2310%2802%2901029-4&partnerID=40&md5=324a5dae715f15cba4eb99e70acbbe5c","Hydroxymethanesulfonate (HMS), an important component in fog and cloud systems, is identified in the negative ion mass spectra of individual particles sampled with an aerosol time-of-flight mass spectrometer (ATOFMS). The peak assignment at mass/charge (m/z)-111 is confirmed by analyzing HMS particles produced in the laboratory. Individual particle mass spectra from a field campaign in Bakersfield, California reveal the presence of HMS in the ambient aerosol during isolated time periods near the dissipation phase of fog suggesting fog processing of the aerosol. The lifetime of HMS in the aerosol is limited to less than 12h. Using the presence of HMS as a tracer for aqueous-phase fog processing, the size distribution indicates that particles with aerodynamic diameters greater than 0.7μm are most affected by the fog and associated high relative humidity. HMS is predominantly associated with particles containing carbon, ammonium, sulfate, and nitrate. Examination of elemental carbon particles containing HMS shows the presence of organic carbon which most likely enhances the hygroscopicity of these particles. This study demonstrates the ability for real-time measurements of fog processing at the single particle level using a chemical tracer for aqueous-phase reactions and highlights the possibilities for using high temporal resolution measurements to gain unique insights into atmospheric processes. © 2003 Elsevier Science Ltd. All rights reserved."
"6603393151;7004008268;7004434383;7005287667;7102496779;7003748130;7004462114;7003566416;57214957433;7005088845;7005228425;","Phase partitioning of aerosol constituents in cloud based on single-particle and bulk analysis",1997,"10.1016/S1352-2310(96)00298-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030616217&doi=10.1016%2fS1352-2310%2896%2900298-1&partnerID=40&md5=829529cb7e807f0ea7777e4220b1a70c","Single-particle analysis, performed by laser microprobe mass spectrometry and bulk analytical techniques were used to study aerosol-cloud interactions within the third field campaign of the EUROTRAC subproject 'ground-based cloud experiments' at the Great Dun Fell, Cumbria, U.K. in spring 1993. The shape of the ridge made it possible for ground-based instrumentation to sample similar parcels of air before, during and after their transit through the cloud. A single jet five-stage minicascade impactor was used for sampling particles of the interstitial aerosol. A second impactor worked in tandem with a counter-flow virtual impactor and collected residues of cloud droplets. Considering marine conditions largest droplets nucleated on sea-salt particles, whereas smaller droplets were formed on sulphate and methane sulphonate containing particles. This clearly indicates chemical inhomogeneities in the droplet phase. Particles, which were disfavoured by droplet formation, often contained the highest amounts of water-insoluble carbonaceous matter. For the submicron size range we found that the carbonaceous matter was always internally mixed with sulphate. The fraction of carbonaceous matter increased with decreasing size. A detectable fraction of particles remained in the cloud interstitial air, although they were in size as well as in composition suitable to form cloud droplets. The findings confirm that nucleation is the most important process affecting phase partitioning in cloud, but that spatial and temporal variations of water vapour supersaturation have also an influence on the observed phase partitioning. Proton induced X-ray emission analysis and light absorption measurements of filter samples showed that the average scavenged fraction was 0.77 for sulphur and 0.57 for soot in clouds formed by continental influenced air and 0.62 and 0.44, respectively, for marine influenced clouds."
"26643041500;57216677408;24311471900;7004713188;","Formation of particulate MSA: Deductions from size distribution measurements in the finnish arctic",1997,"10.3402/tellusb.v49i2.15959","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031464591&doi=10.3402%2ftellusb.v49i2.15959&partnerID=40&md5=9f492f04785316b77191037ca0dcf73a","Formation of particulate MSA was studied by conducting a field campaign in the Finnish Arctic. Based on continuous mass size distributions extracted from impactor measurements, 4 MSA modes were identified: an accumulation mode centered between 0.3-0.5 μm of particle aerodynamic diameter, an Aitken mode below 0.1 μm, and 2 supermicron modes that peaked at 2-3 and 7-10 μm, respectively. The lower supermicron mode resulted primarily from the reaction of gaseous MSA with sea salt particles, and the upper mode probably from its reaction with soil-derived particles. From 70 to 90% of the MSA was found in the accumulation mode, where it was distributed very similarly to ammonium. The overall MSA to nss-SO2-4 ratio, R, ranged from 2 to 34%, with most of this variation resulting from different degrees of anthropogenic perturbation in the measured air masses. When comparing different-size particles, R was clearly the highest in the Aitken mode, suggesting that MSA and sulfate contribute with comparable magnitudes to nuclei condensational growth at high latitudes during the summer. The evident variation of R with particle size, together with potential enhanced MSA production in air influenced by pollution, demonstrate further that one needs to be extremely careful when using observed MSA to nss-SO2-4 ratios for estimating the contribution of biogenic sources to total particulate sulfate in different environments. Strong indications on the saturation of MSA over accumulation-mode particles were found. The saturation effect was hypothesized to explain, in part, the observed large partitioning of MSA in the supermicron mode in warm and very acidic aerosol systems. The distribution of submicron MSA, including potential saturation, was shown to be affected significantly by cloud processing."
"56576520000;6603431534;10040054900;","Clouds, precipitation, and marine boundary layer structure during the MAGIC field campaign",2015,"10.1175/JCLI-D-14-00320.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84926058963&doi=10.1175%2fJCLI-D-14-00320.1&partnerID=40&md5=acb193c8f9c5cd3950567771d9d45aad","The recent ship-based Marine ARM GCSS Pacific Cross-Section Intercomparison (GPCI) Investigation of Clouds (MAGIC) field campaign with the marine-capable Second ARM Mobile Facility (AMF2) deployed on the Horizon Lines cargo container M/V Spirit provided nearly 200 days of intraseasonal high-resolution observations of clouds, precipitation, and marine boundary layer (MBL) structure on multiple legs between Los Angeles, California, and Honolulu, Hawaii. During the deployment, MBL clouds exhibited a much higher frequency of occurrence than other cloud types and occurred more often in the warm season than in the cold season. MBL clouds demonstrated a propensity to produce precipitation, which often evaporated before reaching the ocean surface. The formation of stratocumulus is strongly correlated to a shallow MBL with a strong inversion and a weak transition, while cumulus formation is associated with a much weaker inversion and stronger transition. The estimated inversion strength is shown to depend seasonally on the potential temperature at 700 hPa. The location of the commencement of systematic MBL decoupling always occurred eastward of the locations of cloud breakup, and the systematic decoupling showed a strong moisture stratification. The entrainment of the dry warm air above the inversion appears to be the dominant factor triggering the systematic decoupling, while surface latent heat flux, precipitation, and diurnal circulation did not play major roles. MBL clouds broke up over a short spatial region due to the changes in the synoptic conditions, implying that in real atmospheric conditions the MBL clouds do not have enough time to evolve as in the idealized models. © 2015 American Meteorological Society."
"7202485447;18635289400;16551540700;23012437100;24344262300;7003377766;7103294028;7101899854;24172779500;","Interactions between biomass-burning aerosols and clouds over Southeast Asia: Current status, challenges, and perspectives",2014,"10.1016/j.envpol.2014.06.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84908622881&doi=10.1016%2fj.envpol.2014.06.036&partnerID=40&md5=68e277eb4a6ca2e1e53230ed3e00de81","The interactions between aerosols, clouds, and precipitation remain among the largest sources of uncertainty in the Earth's energy budget. Biomass-burning aerosols are a key feature of the global aerosol system, with significant annually-repeating fires in several parts of the world, including Southeast Asia (SEA). SEA in particular provides a ”natural laboratory” for these studies, as smoke travels from source regions downwind in which it is coupled to persistent stratocumulus decks. However, SEA has been under-exploited for these studies. This review summarizes previous related field campaigns in SEA, with a focus on the ongoing Seven South East Asian Studies (7-SEAS) and results from the most recent BASELInE deployment. Progress from remote sensing and modeling studies, along with the challenges faced for these studies, are also discussed. We suggest that improvements to our knowledge of these aerosol/cloud effects require the synergistic use of field measurements with remote sensing and modeling tools. © 2014 Elsevier Ltd. All rights reserved."
"6701647194;7401595673;34882294600;6603017725;7004444029;35846644300;","Combined passive and active microwave observations of soil moisture during CLASIC",2009,"10.1109/LGRS.2009.2028441","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70350303015&doi=10.1109%2fLGRS.2009.2028441&partnerID=40&md5=0b4c8a22352ef4d73551cd3f1a00a867","An important research direction in advancing higher spatial resolution and better accuracy in soil moisture remote sensing is the integration of active and passive microwave observations. In an effort to address this objective, an airborne instrument, the passive/active L-band sensor (PALS), was flown over two watersheds as part of the cloud and land surface interaction campaign (CLASIC) conducted in Oklahoma in 2007. Eleven flights were conducted over each watershed during the field campaign. Extensive ground observations (soil moisture, soil temperature, and vegetation) were made concurrent with the PALS measurements. Extremely wet conditions were encountered. As expected from previous research, the radiometer-based retrievals were better than the radar retrievals. The standard error of estimates (SEEs) of the retrieved soil moisture using only the PALS radiometer data were 0.048 m3/m3 for Fort Cobb (FC) and 0.067 m3/m3 for the Little Washita (LW) watershed. These errors were higher than typically observed, which is likely the result of the unusually high soil moisture and standing water conditions. The radar-only-based retrieval SEEs were 0.092 m3/m3 for FC and 0.079 m3/m3 for LW. Radar retrievals in the FC domain were particularly poor due to the high vegetation water content of the agricultural fields. These results indicate the potential for estimating soil moisture for low-vegetation water content domains from radar observations using a simple vegetation model. Results also showed the compatibility between passive and active microwave observations and the potential for combining the two approaches. © 2009 IEEE."
"35264611800;16308514000;7101846027;7003591311;7006572336;57196499374;","Marine stratocumulus aerosol-cloud relationships in the MASE-II experiment: Precipitation susceptibility in eastern Pacific marine stratocumulus",2009,"10.1029/2009JD012774","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954205057&doi=10.1029%2f2009JD012774&partnerID=40&md5=d0a1b8f4f0c5048fc50c0ed2774cfe18","[1] Observational data on aerosol-cloud-drizzle relationships in marine stratocumulus are presented from the second Marine Stratus/Stratocumulus Experiment (MASE-II) carried out in July 2007 over the eastern Pacific near Monterey, California. Observations, carried out in regions of essentially uniform meteorology with localized aerosol enhancements due to ship exhaust (""ship tracks""), demonstrate, in accord with those from numerous other field campaigns, that increased cloud drop number concentration N<inf>c</inf> and decreased cloud top effective radius r<inf>e</inf> are associated with increased subcloud aerosol concentration. Modulation of drizzle by variations in aerosol levels is clearly evident. Variations of cloud base drizzle rate R <inf>cb</inf> are found to be consistent with the proportionality, R <inf>cb</inf> ∝ H3/N<inf>c</inf>, where H is cloud depth. Simultaneous aircraft and A-Train satellite observations are used to quantify the precipitation susceptibility of clouds to aerosol perturbations in the eastern Pacific region. Copyright 2009 by the American Geophysical Union."
"7003848718;","Boundary layer mass, water, and heat budgets in wintertime cold-air outbreaks from the arctic sea ice",1997,"10.1175/1520-0493(1997)125<1824:BLMWAH>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000679059&doi=10.1175%2f1520-0493%281997%29125%3c1824%3aBLMWAH%3e2.0.CO%3b2&partnerID=40&md5=3fc560efcfa53669fbdbb6e603d1081c","Eleven cold-air outbreaks from the Arctic sea ice to the open water of the Fram Strait and the Norwegian Sea have been monitored by aircraft during the field campaigns ARKTIS 1991 and ARKTIS 1993. Budgets of mass, water vapor, water, and heat in the atmospheric boundary layer are computed for boxes that are located at different distances from the ice edge ranging from the marginal ice zone to several hundred kilometers downstream. Averaged over all cold-air outbreaks, the large-scale flow is divergent near the ice edge and convergent at larger distances from the ice edge. Regardless of divergence, the large-scale flow exports everywhere water vapor, water, and heat from an atmospheric box within the boundary layer. In the case of the water vapor budget this export and the loss by condensation in clouds are compensated by evaporation from the sea surface. Both the condensation in clouds and surface evaporation increase in downstream direction, as does their ratio from about 0.4 near the ice edge to about 0.8 at distances greater than 300 km. In the water budget, the source by condensation in clouds is compensated by two sinks: large-scale flow export and precipitation. Precipitation increases absolutely from about 1-4 mm day-1 in downstream direction but the ratio of precipitation versus condensation remains approximately constant at a value of 0.75. In contrast to the water vapor and water budgets with only one source, the heat budget has several sources, namely, surface heat flux, entrainment heat flux, condensation in clouds, and possibly radiation, which compensate for the heat export by the large-scale flow. The relative importance of these sources changes with distance from the ice edge. Near the ice edge, the surface heat flux at the first place and the entrainment flux at the second place are the relevant sources, while farther downstream in the region of deep convection - latent heat release by condensation is the dominating heat source. Here, the surface heat flux is of secondary importance and the entrainment flux plays a minor role. Since a systematic transition from roll-like to cellular-like convection patterns is present in Arctic cold-air outbreaks, the differences in the budgets with respect to distance from the ice edge apply as well to the regions of rolls and cells, respectively. It is hypothesized that mesoscale cellular convection with cloud depths of more than 1 km does not occur unless the Bowen ratio is less than about 0.6."
"6701684534;7004484970;7102643810;7006575272;7005071296;7005890897;52563460500;7403424856;6701501555;6603431534;56940002600;56940697400;7402717381;6603768446;6701653010;56900025900;6602681732;","Global precipitation measurement cold season precipitation experiment (GCPEX): For measurement's sake, let it snow",2015,"10.1175/BAMS-D-13-00262.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946070237&doi=10.1175%2fBAMS-D-13-00262.1&partnerID=40&md5=9de0a0568b45e38cb9ef6355cbb7424a","The GPM Cold Season Precipitation Experiment (GCPEx), a collaboration between NASA GPM ground validation (GV) program and its international partner, Environment Canada (EC), provided both new datasets and physical insights related to the snowfall process to ultimately improve falling-snow retrievals. The GCPEx field campaign occurred in Ontario, Canada, from 15 January to 3 March 2012. GCPEx collected microphysical properties, associated remote sensing observations, and coordinated model simulations of precipitating snow. The coordinated measurement strategy used stacked high-altitude GPM airborne remote sensing simulator instrumentation and in situ cloud aircraft flights with three research aircraft sampling within a broader network of five ground sites taking surface in situ and volumetric observations. Data collected during this field campaign exceeded all expectations, with measurements of heavy fluffy, non-melted, rate, moderate and light falling-snow rates, along with mixed-phase and rain cases. It is anticipated that the GCPEx dataset will satisfy the majority of GPM falling-snow retrieval algorithm validation objectives originally set forward for the experiment. These 3D datasets are suitable for conducting observational and modeling-based studies of bulk- and/or particle-scale snow microphysical and scattering properties observed at the ground, through the atmospheric column, and at high altitudes as observed from the vantage point of remote sensing instrumentation deployed on the GPM Core Observatory."
"8916335600;8718203900;55332214100;","Continuous variability in thunderstorm primary electrification and an evaluation of inverted-polarity terminology",2014,"10.1016/j.atmosres.2012.10.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889597629&doi=10.1016%2fj.atmosres.2012.10.009&partnerID=40&md5=523988b12b77b7b7c76b357b3bd271b9","Several field campaigns since the year 2000 have focused on anomalously electrified or ""inverted polarity"" thunderstorms. This study synthesizes these recent results, and considers how variability in the non-inductive relative-growth rate electrification mechanism might clarifying the meaning of ""inverted polarity"". Instead of falling into two polarity classes, electrification and charge structure in strong updrafts vary continuously, as expected if depletion of supercooled water is a primary control on electrification. Two- or three-dimensional storm flows or other electrification mechanisms are required to combine one or more of these electrification regimes into ""inverted"" or otherwise complicated local charge sequences. Cloud flashes that result from these local charge sequences should be termed ""positive"" and ""negative"" instead of ""normal"" and ""inverted"" because cloud flashes of either polarity can occur at any altitude in thunderstorms. © 2012 Elsevier B.V."
"6603550074;55262499900;55702592400;55717441600;35413553600;14025125600;7402545909;55967620900;","IASI spectral radiance validation inter-comparisons: Case study assessment from the JAIVEx field campaign",2010,"10.5194/acp-10-411-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-74549214297&doi=10.5194%2facp-10-411-2010&partnerID=40&md5=ecec7e8cb9085e567aa780efe9ec7dd0","Advanced satellite sensors are tasked with improving global-scale measurements of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring, and environmental change detection. Measurement system validation is crucial to achieving this goal and maximizing research and operational utility of resultant data. Field campaigns employing satellite under-flights with well-calibrated Fourier Transform Spectrometer (FTS) sensors aboard high-altitude aircraft are an essential part of this validation task. The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed-Interferometer (NAST-I) has been a fundamental contributor in this area by providing coincident high spectral and spatial resolution observations of infrared spectral radiances along with independently-retrieved geophysical products for comparison with like products from satellite sensors being validated. This manuscript focuses on validating infrared spectral radiance from the Infrared Atmospheric Sounding Interferometer (IASI) through a case study analysis using data obtained during the recent Joint Airborne IASI Validation Experiment (JAIVEx) field campaign. Emphasis is placed upon the benefits achievable from employing airborne interferometers such as the NAST-I since, in addition to IASI radiance calibration performance assessments, cross-validation with other advanced sounders such as the AQUA Atmospheric InfraRed Sounder (AIRS) is enabled."
"7202772927;55699179200;6701681018;35467186900;","The atmospheric energy budget and large-scale precipitation efficiency of convective systems during TOGA COARE, GATE, SCSMEX, and ARM: Cloud-resolving model simulations",2004,"10.1175/1520-0469(2004)061<2405:TAEBAL>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-8744314558&doi=10.1175%2f1520-0469%282004%29061%3c2405%3aTAEBAL%3e2.0.CO%3b2&partnerID=40&md5=3bcaf1f83c799b7e296c9a477a3f21f3","A two-dimensional version of the Goddard Cumulus Ensemble (GCE) model is used to simulate convective systems that developed in various geographic locations (east Atlantic, west Pacific, South China Sea, and Great Plains in the United States). Observed large-scale advective tendencies for potential temperature, water vapor mixing ratio, and horizontal momentum derived from field campaigns are used as the main forcing. The atmospheric temperature and water vapor budgets from the model results show that the two largest terms are net condensation (heating/drying) and imposed large-scale forcing (cooling/moistening) for tropical oceanic cases though not for midlatitude continental cases. These two terms are opposite in sign, however, and are not the dominant terms in the moist static energy budget. The balance between net radiation, surface latent heat flux, and net condensational heating vary in these tropical cases, however. For cloud systems that developed over the South China Sea and eastern Atlantic, net radiation (cooling) is not negligible in the temperature budget; it is as large as 20% of the net condensation. However, shortwave heating and longwave cooling are in balance with each other for cloud systems over the west Pacific region such that the net radiation is very small. This is due to the thick anvil clouds simulated in the cloud systems over the Pacific region. The large-scale advection of moist static energy is negative, as a result of a larger absolute value of large-scale advection of sensible heat (cooling) compared to large-scale latent heat (moistening) advection in the Pacific and Atlantic cases. For three cloud systems that developed over a midlatitude continent, the net radiation and sensible and latent heat fluxes play a much more important role. This means that the accurate measurement of surface fluxes and radiation is crucial for simulating these midlatitude cases. The results showed that large-scale mean (multiday) precipitation efficiency (PE) varies from 24% to 31% (or 32% to 45% using a different definition of PE) between cloud systems from different geographic locations. The model results showed that there is no clear relationship between the PE and rainfall, the positive cloud condensation (condensation plus deposition), or the large-scale forcing. But, the model results suggest that cases with large, positive net condensation terms in the moist static energy budget tend to have a large PE. The PE and its relationship with relative humidity and the vertical shear of the horizontal wind are also examined using 6-hourly model data. The model results suggest that there is no clear relationship between the individual PE and total mass-weighted relative humidity or the middle- and upper-tropospheric moisture for each case. The model results suggest that for the west Pacific and east Atlantic cases, PE slightly decreases with increasing middle-tropospheric wind shear in low to moderate shear regimes. The correlation (based on the best polynomial fit) is quite weak however. No strong relationship between PE and wind shear was found for the South China Sea and cases over the United States. © 2004 American Meteorological Society."
"7003928082;7101899854;35203432500;7103294028;26661481400;16551540700;7404548584;7102018821;35985515200;","An assessment of the surface longwave direct radiative effect of airborne Saharan dust during the NAMMA field campaign",2010,"10.1175/2009JAS3257.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953327402&doi=10.1175%2f2009JAS3257.1&partnerID=40&md5=5147196b66bda4e88258e3c3e7823584","In September 2006, NASA Goddard's mobile ground-based laboratories were deployed to Sal Island in Cape Verde (16.73°N, 22.93°W) to support the NASA African Monsoon Multidisciplinary Analysis (NAMMA) field study. The Atmospheric Emitted Radiance Interferometer (AERI), a key instrument for spectrally characterizing the thermal IR, was used to retrieve the dust IR aerosol optical depths (AOTs) in order to examine the diurnal variability of airborne dust with emphasis on three separate dust events. AERI retrievals of dust AOT are compared with those from the coincident/collocated multifilter rotating shadowband radiometer (MFRSR), micropulse lidar (MPL), and NASA Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) sensors. The retrieved AOTs are then inputted into the Fu-Liou 1D radiative transfer model to evaluate local instantaneous direct longwave radiative effects (DRELW) of dust at the surface in cloud-free atmospheres and its sensitivity to dust microphysical parameters. The top-of-atmosphere DRELW and longwave heating rate profiles are also evaluated. Instantaneous surface DRELW ranges from 2 to 10 W m-2 and exhibits a strong linear dependence with dust AOT yielding a DRELW of 16 W m-2 per unit dust AOT. The DRELW is estimated to be ~42% of the diurnally averaged direct shortwave radiative effect at the surface but of opposite sign, partly compensating for the shortwave losses. Certainly nonnegligible, the authors conclude that DRELW can significantly impact the atmospheric energetics, representing an important component in the study of regional climate variation. © 2010 American Meteorological Society."
"55718206700;7202772927;7005742394;35467186900;55699179200;","Sensitivity of a cloud-resolving model to bulk and explicit bin microphysical schemes. Part I: Comparisons",2009,"10.1175/2008JAS2646.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65549166920&doi=10.1175%2f2008JAS2646.1&partnerID=40&md5=1ce0ded8cd7d1dcd738150cafe406496","A two-dimensional cloud-resolving model is used to study the sensitivities of two microphysical schemes, a bulk scheme and an explicit spectral bin scheme, in simulating a midlatitude summertime squall line [Preliminary Regional Experiment for Storm-Scale Operational and Research Meteorology (PRE-STORM), 10-11 June 1985]. In this first part of a two-part paper, the developing and mature stages of simulated storms are compared in detail. Some variables observed during the field campaign are also presented for validation. It is found that both schemes agree well with each other, and also with published observations and retrievals, in terms of storm structures and evolution, average storm flow patterns, pressure and temperature perturbations, and total heating profiles. The bin scheme is able to produce a much more extensive and homogeneous stratiform region, which compares better with observations. However, instantaneous fields and high temporal resolution analyses show distinct characteristics in the two simulations. During the mature stage, the bulk simulation produces a multicell storm with convective cells embedded in its stratiform region. Its leading convection also shows a distinct life cycle (strong evolution). In contrast, the bin simulation produces a unicell storm with little temporal variation in its leading cell regeneration (weak evolution). More detailed, high-resolution observations are needed to validate and, perhaps, generalize these model results. Interactions between the cloud microphysics and storm dynamics that produce the sensitivities described here are discussed in detail in Part II of this paper. © 2009 American Meteorological Society."
"6602574676;35468686100;6603944055;7202727242;6602137800;","Airborne spectral measurements of ocean directional reflectance",2005,"10.1175/JAS3386.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-18544364605&doi=10.1175%2fJAS3386.1&partnerID=40&md5=c7ea646833a7e2aa4f837b23b57fe340","The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair 580 (CV-580) research aircraft during the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaign and obtained measurements of bidirectional reflectance distribution function (BRDF) of the ocean in July and August 2001 under different illumination conditions with solar zenith angles ranging from 15° to 46°. The BRDF measurements were accompanied by concurrent measurements of atmospheric aerosol optical thickness and column water vapor above the airplane. The method of spherical harmonics with Cox-Munk wave-slope distribution is used in a new algorithm developed for this study to solve the atmosphere-ocean radiative transfer problem and to remove the effects of the atmosphere from airborne measurements. The algorithm retrieves simultaneously the wind speed and full ocean BRDF (sun's glitter and water-leaving radiance) from CAR measurements and evaluates total albedo and equivalent albedo for the water-leaving radiance outside the glitter. Results show good overall agreement with other measurements and theoretical simulations, with the anisotropy of the water-leaving radiance clearly seen. However, the water-leaving radiance does not show a strong dependence on solar zenith angle as suggested by some theoretical studies. The spectral albedo was found to vary from 4.1%-5.1% at λ = 0.472 μm to 2.4%-3.5% for λ ≥ 0.682 μm. The equivalent water-leaving albedo ranges from 1.0%-2.4% at λ = 0.472 μm to 0.1%-0.6% for λ = 0.682 μm and 0.1%-0.3% for λ = 0.870 μm. Results of the validation of the Cox-Munk model under the conditions measured show that although the model reproduces the shape of sun's glitter on average with an accuracy of better than 30%, it underestimates the center of the sun's glitter reflectance by about 30% for low wind speeds (&lt;2-3 m s-1). In cases of high wind speed, the model with Gram-Charlier expansion seems to provide the best fit. © 2005 American Meteorological Society."
"6506392154;6506767494;7005893321;35477504600;","Cloudwater chemistry in the subcooled droplet regime at Mount Sonnblick (3106 M A.S.L., Salzburg, Austria)",1994,"10.1007/BF00479800","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028410969&doi=10.1007%2fBF00479800&partnerID=40&md5=2a718d7798326b3ab23bec562be42c56","Cloudwater and wet precipitation (snow) samples were collected at Mount Sonnblick during two field campaigns in May and November 1991. A newly designed active cloud water samples was used. Concentrations of major anions, cations and carboxylic acids were determined. Cloudwater and wet precipitation samples were generally more acidic in the warm season than in the cold season. Average cloudwater pH was 4.2 in May and 4.5 in November, average pH in snow was 4.4 in May and 5.1 in November. Average levels for sulfate (May: 96 μeq L-1, November: 64 μeq L-1) and nitrate (May: 27 μeq L-1, November: 32 μeq L-1) in cloudwater at SBO (3 km altitude) were considerably lower than at high mountain sites (0.9-2 km altitude) in the Eastern U.S.A. Cold season levels of sulfate in cloud water at SBO were as low as cloud water levels observed in Alaska. Equivalent concentrations of sulfate, nitrate and ammonium in snow precipitation were basically lower or equal compared to cloudwater but showed higher concentrations and stronger acidity in both phases in May than in November. Cloud to snow ratios for major ions were higher in November showing a wider spread than in May. Average cloud to snow ratios for sulfate were 2.4 in May and 3.5 in November. For nitrate the ratio was 1.7 in May and 2.1 in November. The lower cloud to snow ratios for nitrate are explained by the ability of the ice phase to scavenge nitric acid. Cloud to snow ratios were similar to measurements from the Swiss Alps and generally equal or lower than high elevation cloud to rain ratios from the U.S.A. Cloud to snow ratios for sulfate were used to reconstruct the mixing ratio of sublimation grown ice phase and cloud water droplets during the riming process of the ice particles in the seeder-feeder mechanism. The mixing ratio of ice phase and cloud droplets was estimated to be 1.4 in May and 2.5 in November. Sulfate to nitrate ratios were higher in cloud water than in snow and within the range of values found in North America. Generally, sulfate was more concentrated than nitrate at an equivalent basis for both cloudwater and rainwater. Total equivalent concentrations of acetate were generally higher than those of formate which is in contrast to measurements at remote high elevation sites in the U.S.A. © 1994 Kluwer Academic Publishers."
"8511991900;7003666669;55405340400;55717074000;7006705919;35572096100;","Representation of Arctic mixed-phase clouds and the Wegener-Bergeron- Findeisen process in climate models: Perspectives from a cloud-resolving study",2011,"10.1029/2010JD015375","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80051846056&doi=10.1029%2f2010JD015375&partnerID=40&md5=96cb596cd44b1b034c7a71e6b1836aa2","Two types of Arctic mixed-phase clouds observed during the ISDAC and M-PACE field campaigns are simulated using a 3-dimensional cloud-resolving model (CRM) with size-resolved cloud microphysics. The modeled cloud properties agree reasonably well with aircraft measurements and surface-based retrievals. Cloud properties such as the probability density function (PDF) of vertical velocity (w), cloud liquid and ice, regimes of cloud particle growth, including the Wegener-Bergeron-Findeisen (WBF) process, and the relationships among properties/processes in mixed-phase clouds are examined to gain insights for improving their representation in General Circulation Models (GCMs). The PDF of the simulated w is well represented by a Gaussian function, validating, at least for arctic clouds, the subgrid treatment used in GCMs. The PDFs of liquid and ice water contents can be approximated by Gamma functions, and a Gaussian function can describe the total water distribution, but a fixed variance assumption should be avoided in both cases. The CRM results support the assumption frequently used in GCMs that mixed phase clouds maintain water vapor near liquid saturation. Thus, ice continues to grow throughout the stratiform cloud but the WBF process occurs in about 50% of cloud volume where liquid and ice co-exist, predominantly in downdrafts. In updrafts, liquid and ice particles grow simultaneously. The relationship between the ice depositional growth rate and cloud ice strongly depends on the capacitance of ice particles. The simplified size-independent capacitance of ice particles used in GCMs could lead to large deviations in ice depositional growth. Copyright 2011 by the American Geophysical Union."
"7501416570;6603478504;7006614768;7003959453;6602093732;16679872900;49662365100;7103174511;","The high-altitude MMIC sounding radiometer for the Global Hawk unmanned aerial vehicle: Instrument description and performance",2011,"10.1109/TGRS.2011.2125973","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052306645&doi=10.1109%2fTGRS.2011.2125973&partnerID=40&md5=65bae8223f939357a58dbf7c858e0c13","The Jet Propulsion Laboratory's High-Altitude Monolithic Microwave Integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a 25-channel cross-track scanning microwave sounder with channels near the 60- and 118-GHz oxygen lines and the 183-GHz water-vapor line. It has previously participated in three hurricane field campaigns, namely, CAMEX-4 (2001), Tropical Cloud Systems and Processes (2005), and NASA African Monsoon Multidisciplinary Analyses (2006). The HAMSR instrument was recently extensively upgraded for the deployment on the Global Hawk (GH) unmanned aerial vehicle platform. One of the major upgrades is the addition of a front-end low-noise amplifier, developed by JPL, to the 183-GHz channel which reduces the noise in this channel to less than 0.1 K at the sensor resolution (∼2 km). This will enable HAMSR to observe much smaller scale water-vapor features. Another major upgrade is an enhanced data system that provides onboard science processing capability and real-time data access. HAMSR has been well characterized, including passband characterization, along-scan bias characterization, and calibrated noise-performance characterization. The absolute calibration is determined in-flight and has been estimated to be better than 1.5 K from previous campaigns. In 2010, HAMSR participated in the NASA Genesis and Rapid Intensification Processes campaign on the GH to study tropical cyclone genesis and rapid intensification. HAMSR-derived products include observations of the atmospheric state through retrievals of temperature, water-vapor, and cloud-liquid-water profiles. Other products include convective intensity, precipitation content, and 3-D storm structure. © 2011 IEEE."
"56060986400;56250185400;23019619200;15059495000;23990280900;6602215448;22133985200;22979686100;6602999057;7403361959;19640523200;55405013100;15926468600;7003414581;6701697023;57214160655;35998927000;7006595513;","Regional modelling of Saharan dust and biomass-burning smoke: Part I: Model description and evaluation",2011,"10.1111/j.1600-0889.2011.00570.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80051966841&doi=10.1111%2fj.1600-0889.2011.00570.x&partnerID=40&md5=44e41f2c62e3666f5e818c5a12756dde","The spatio-temporal evolution of the Saharan dust and biomass-burning plume during the SAMUM-2 field campaign in January and February 2008 is simulated at 28 km horizontal resolution with the regional model-system COSMO-MUSCAT. The model performance is thoroughly tested using routine ground-based and space-borne remote sensing and local field measurements. Good agreement with the observations is found in many cases regarding transport patterns, aerosol optical thicknesses and the ratio of dust to smoke aerosol. The model also captures major features of the complex aerosol layering. Nevertheless, discrepancies in the modelled aerosol distribution occur, which are analysed in detail. The dry synoptic dynamics controlling dust uplift and transport during the dry season are well described by the model, but surface wind peaks associated with the breakdown of nocturnal low-level jets are not always reproduced. Thus, a strong dust outbreak is underestimated. While dust emission modelling is a priori more challenging, since strength and placement of dust sources depend on on-line computed winds, considerable inaccuracies also arise in observation-based estimates of biomass-burning emissions. They are caused by cloud and spatial errors of satellite fire products and uncertainties in fire emission parameters, and can lead to unrealistic model results of smoke transport. © 2011 The Authors Tellus B © 2011 John Wiley & Sons A/S."
"8871497700;7006146719;6602515941;25825715600;57192091713;55629222300;22236015300;7402781278;23668415500;7102643810;7005071296;7410177774;10640192200;57192169322;7003750797;24169741400;8568391400;55682775100;24480463300;7006821210;55951906300;14024872700;8927405700;8705440100;36076994600;24491934500;7007162501;7006599647;6506254483;6504212618;13204389400;","A field campaign to elucidate the impact of biogenic aerosols on clouds and climate",2016,"10.1175/BAMS-D-14-00199.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84999122281&doi=10.1175%2fBAMS-D-14-00199.1&partnerID=40&md5=d5b2511be0eb73ee3cf0e7cd6ed6f0b5","Observations obtained during an 8-month deployment of AMF2 in a boreal environment in Hyytiälä, Finland, and comprehensive in situ data from the SMEAR II station enable the characterization of biogenic aerosol, clouds, and precipitation and their interactions. © 2016 American Meteorological Society."
"9240820800;6507949344;7004672744;7006927061;55703811800;57199451263;7003974635;7403968786;7402841077;","Validation of GOES-R satellite land surface temperature algorithm using SURFRAD ground measurements and statistical estimates of error properties",2012,"10.1109/TGRS.2011.2162338","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84873186644&doi=10.1109%2fTGRS.2011.2162338&partnerID=40&md5=1a6abbdf866143956bfaca2f0dfe7eca","Validation of satellite land surface temperature (LST) is a challenge because of spectral, spatial, and temporal variabilities of land surface emissivity. Highly accurate in situ LST measurements are required for validating satellite LST products but are very hard to obtain, except at discrete points or for very short time periods (e.g., during field campaigns). To compare these field-measured point data withmoderate-resolution (~1 km) satellite products requires a scaling process that can introduce errors that ultimately exceed those in the satellite-derived LST products whose validation is sought. This paper presents a new method of validating the Geostationary Operational Environmental Satellite (GOES) R-Series (GOES-R) Advanced Baseline Imager (ABI) LST algorithm. It considers the error structures of both ground and satellite data sets. The method applies a linear fitting model to the satellite data and coregistered ""match-up"" ground data for estimating the precisions of both data sets. In this paper, GOES-8 Imager data were used as a proxy of the GOES-R ABI data for the satellite LST derivation. The in situ data set was obtained from the National Oceanic and Atmospheric Administration's SURFace RADiation (SURFRAD) budget network using a stringent match-up process. The data cover one year of GOES-8 Imager observations over six SURFRAD sites. For each site, more than 1000 cloud-free match-up data pairs were obtained for day and night to ensure statistical significance. The average precision over all six sites was found to be 1.58 K, as compared to the GOES-R LST required precision of 2.3 K. The least precise comparison at an individual SURFRAD site was 1.8 K. The conclusion is that, for these ground truth sites, the GOES-R LST algorithm meets the specifications and that an upper boundary on the precision of the satellite LSTs can be determined. © 2011 IEEE."
"7004020627;8631673500;8631673200;6603230487;8711886600;7402177459;","SPACCIM: A parcel model with detailed microphysics and complex multiphase chemistry",2005,"10.1016/j.atmosenv.2005.02.038","https://www.scopus.com/inward/record.uri?eid=2-s2.0-22144486873&doi=10.1016%2fj.atmosenv.2005.02.038&partnerID=40&md5=08e3e8a5f2d6467759de3221b7b31f89","Multiphase processes, such as the uptake of gases by clouds or the production of gas phase halogens from particulate halides are of increasing importance for the understanding of the tropospheric system. Mass transfer and chemical reactions modify the concentrations of stable compounds and oxidants in either phase. The parcel model SPACCIM is presented which combines a complex multiphase chemical model with a detailed microphysical model. For this purpose, a new coupling scheme is implemented. The description of both components is given for a fine-resolved particle/drop spectrum. The SPACCIM approach allows the coupling of multiphase chemical models with microphysical codes of various types. An efficient numerical solution of such systems is only possible utilizing the special structure. An implicit time-integration scheme with an adapted sparse solver for the linear systems is applied. Its numerical efficiency and robustness is analyzed for two scenarios and versions of different complexity of the multiphase chemistry mechanism CAPRAM. The sensitivity of simulation results against variations in the particle/droplet size resolution, the coupling time step and numerical control parameters is discussed. Guidelines for an ""optimal"" choice of control parameters are derived from this sensitivity study. The coupling scheme operation is always robust and reliable. Model simulations are compared with several measurements from the FEBUKO field campaign. Simulated and measured results show a reasonable agreement. © 2005 Elsevier Ltd. All rights reserved."
"7006211890;55454856700;7005828214;","A comparison of in-cloud measurements obtained with six PMS 2D-C probes",1993,"10.1175/1520-0426(1993)010<0180:ACOICM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027388497&doi=10.1175%2f1520-0426%281993%29010%3c0180%3aACOICM%3e2.0.CO%3b2&partnerID=40&md5=82766086111252586dd5082b3b76fd4d","During a preparatory experiment (PREICE) for the field campaign of the International Cirrus Experiment (ICE), six different Particle Measuring Systems (PMS) 2D-C probes belonging to five research organizations were intercompared. Three of these probes were original versions (2D-C), the three others being updated instruments (2D2-C version). The comparisons were performed using data obtained during flights in various types of warm and glaciated clouds. Large differences may be obtained when two different but common methods of calculation of the sample time are applied to data from a single probe. This appears to be related to timing errors within the probe data stream. There is a need for the standardization of processing schemes, where possible, in order to reduce the uncertainties in results obtained during multiaircraft cooperative experiments. -from 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"
"6602177985;37027011900;26634569400;37026400000;8618154900;57198394115;7101600670;","On the relationship between water vapour field evolution and the life cycle of precipitation systems",2011,"10.1002/qj.785","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79951883810&doi=10.1002%2fqj.785&partnerID=40&md5=1023e7f5577497431d4a1bee75fbbe66","In this work, we investigate the relationship between the structure and evolution (from initiation to decay) of precipitation systems, and the associated water vapour distributions during the COPS (Convective Orographically-induced Precipitation Study). This international field campaign took place over an area from the Vosges to the Black Forest Mountains, across the Rhine Valley, in summer 2007. In particular, we consider water vapour retrieval through GPS integrated water vapour 2D maps and 3D tomography, and compare these to precipitation systems observed with the ground-based C-band POLDIRAD weather radar. We have demonstrated the predominant role of water vapour as a precursor to convective initiation for local convective cell generation. Water vapour accumulation on the crest of the orography is associated with ridge convection, while water vapour passing over the mountain top and creating valley outflows generates lee-side convection, often triggered by a small hill positioned within or close to the valley exit, or by a local convergence with the water vapour field over the plain. We have also noted that frontal systems seem to develop preferentially where the largest amount of water vapour is available. Likewise, in the case of frontal systems, well-formed synoptic-scale storms are associated with high water vapour signatures, while weaker systems with embedded convection appear to trail high water vapour areas where the convective element is associated with local water vapour depletion. This latter aspect could be the signature of convective cloud formation, when water vapour is transferred into liquid water, before the onset of precipitation. Copyright © 2011 Royal Meteorological Society Copyright © 2011 Royal Meteorological Society."
"36538539800;36065603800;27171906700;55113736500;7005956394;7402822814;7405728922;6701756440;","A comparative study of nucleation parameterizations: 2. Three-dimensional model application and evaluation",2010,"10.1029/2010JD014151","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78149289941&doi=10.1029%2f2010JD014151&partnerID=40&md5=82b44e6093e6d80289461f116283ed8b","Following the examination and evaluation of 12 nucleation parameterizations presented in part 1, 11 of them representing binary, ternary, kinetic, and cluster-activated nucleation theories are evaluated in the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) modeling system version 4.4. The 12-28 June 1999 Southern Oxidants Study episode is selected as a testbed to evaluate simulated particulate matter (PM) number and size predictions of CMAQ with different nucleation parameterizations. The evaluation shows that simulated domain-wide maximum PM<inf>2.5</inf> number concentrations with different nucleation parameterizations can vary by 3 orders of magnitude. All parameterizations overpredict (by a factor of 1.4 to 1.7) the total number concentrations of accumulation-mode PM and significantly underpredict (by factors of 1.3 to 65.7) those of Aitken-mode PM, resulting in a net underprediction (by factors of 1.3 to 13.7) of the total number concentrations of PM<inf>2.5</inf> under a polluted urban environment at a downtown station in Atlanta. The predicted number concentrations for Aitken-mode PM at this site can vary by up to 3 orders of magnitude, and those for accumulation-mode PM can vary by up to a factor of 3.2, with the best predictions by the power law of Sihto et al. (2006) (NMB of -31.7%) and the worst predictions by the ternary nucleation parameterization of Merikanto et al. (2007) (NMB of -93.1%). The ternary nucleation parameterization of Napari et al. (2002) gives relatively good agreement with observations but for a wrong reason. The power law of Kuang et al. (2008) and the binary nucleation parameterization of Harrington and Kreidenweis (1998) give better agreement than the remaining parameterizations. All the parameterizations fail to reproduce the observed temporal variations of PM number, volume, and surface area concentrations. The significant variation in the performance of these parameterizations is caused by their different theoretical bases, formulations, and dependence on temperature, relative humidity, and the ambient levels of H<inf>2</inf>SO<inf>4</inf> and NH <inf>3</inf>. The controlling processes are different for PM number, mass, and surface areas. At urban/rural locations, some PM processes (e.g., homogeneous nucleation) and/or vertical transport may dominate the production of PM <inf>2.5</inf> number, and emissions, or PM processes, or vertical transport or their combinations may dominate the production of PM<inf>2.5</inf> mass and surface area. Dry deposition or some PM processes such as coagulation may dominate PM<inf>2.5</inf> number loss, and horizontal and vertical transport, and cloud processes (e.g., cloud scavenging and wet deposition) may dominate the loss of PM<inf>2.5</inf> mass and surface area concentrations. Sensitivity simulations show that the PM number and size distribution predictions are most sensitive to prescribed emission fractions of Aitken and accumulation-mode PM and the assumed initial PM size distribution, in addition to different nucleation parameterizations. Copyright 2010 by the American Geophysical Union."
"11839267100;7202772927;7401701196;7006957668;55745955800;35467186900;","On the sensitivity of atmospheric ensembles to cloud microphysics in long-term cloud-resolving model simulations",2008,"10.2151/jmsj.86A.45","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971440030&doi=10.2151%2fjmsj.86A.45&partnerID=40&md5=e0f13a763430a38bbbfba036360c80a9","Month-long large-scale forcing data from two field campaigns are used to drive a cloud-resolving model (CRM) and produce ensemble simulations of clouds and precipitation. Observational data are then used to evaluate the model results. To improve the model results, a new parameterization of the Bergeron process is proposed that incorporates the number concentration of ice nuclei (IN). Numerical simulations reveal that atmospheric ensembles are sensitive to IN concentration and ice crystal multiplication. Two- (2D) and three-dimensional (3D) simulations are carried out to address the sensitivity of atmospheric ensembles to model dimensionality. It is found that the ensembles with high IN concentration are more sensitive to dimensionality than those with low IN concentration. Both the analytic solutions of linear dry models and the CRM output show that there are more convective cores with stronger updrafts in 3D simulations than in 2D, which explains the differing sensitivity of the ensembles to dimensionality at different IN concentrations. © 2008, Meteorological Society of Japan."
"14044750400;7103293742;7006728825;57203492395;7402579146;","A review of the initiation of precipitating convection in the United Kingdom",2006,"10.1256/qj.05.54","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746218766&doi=10.1256%2fqj.05.54&partnerID=40&md5=935d6ae509ca15ff8ff1b51a8fafd198","Recent severe weather events have prompted the European scientific community to assess the current understanding of convective processes with a view to more detailed and accurate forecasting. The initial development of convective cells remains one of the least understood aspects and one in which limited research has taken place. The important processes can be split into three main areas: boundary-layer forcing, upper-level forcing and secondary generation. This paper is a review of the mechanisms responsible for the initiation of precipitating convection in the United Kingdom; i.e. why convective clouds form and develop into precipitating clouds in a particular location. The topography of the United Kingdom has a large influence on the initiation of convection. Boundary-layer forcings determine the specific location where convection is triggered within larger regions of potential instability. These latter regions are created by mesoscale or synoptic-scale features at a higher level such as dry intrusions and mesoscale vortices. Second-generation cells are those formed by the interaction of outflow from convective clouds with the surrounding environmental air. Large, long-lived thunderstorm complexes can develop when new cells are repeatedly triggered on one side of the system. Current and future field campaigns along with the development of high-resolution modelling will enable these processes to be investigated in more detail than has previously been achieved. © Royal Meteorological Society, 2006. The contribution of P. A. Clark is Crown copyright."
"57196540445;7005941217;6701518904;7003620360;15072278700;6507496639;15072178500;57193261640;57204302411;7004839466;7003765782;7202711754;7004249622;","In situ measurements of background aerosol and subvisible cirrus in the tropical tropopause region",2002,"10.1029/2001JD001385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041619719&doi=10.1029%2f2001JD001385&partnerID=40&md5=aa1776a92cc3463d743bdaf160532a89","[1] In situ aerosol measurements were performed in the Indian Ocean Intertropical Convergence Zone (ITCZ) region during the Airborne Polar Experiment-Third European Stratospheric Experiment on Ozone (APE-THESEO) field campaign based in Mahe, Seychelles between 24 February and 6 March 1999. These are measurements of particle size distributions with a laser optical particle counter of the Forward Scattering Spectrometer Probe (FSSP)-300 type operated on the Russian M-55 high-altitude research aircraft Geophysica in the tropical upper troposphere and lower stratosphere up to altitudes of 21 km. On 24 and 27 February 1999, ultrathin layers of cirrus clouds were penetrated by Geophysica directly beneath the tropical tropopause at 17 km pressure altitude and temperatures below 190 K. These layers also were concurrently observed by the Ozone Lidar Experiment (OLEX) lidar operating on the lower-flying German DLR Falcon research aircraft. The encountered ultrathin subvisual cloud layers can be characterized as (1) horizontally extending over several hundred kilometers, (2) persisting for at least 3 hours (but most likely much longer), and (3) having geometrical thicknesses of 100-400 m. These cloud layers belong to the geometrically and optically thinnest ever observed. In situ particle size distributions covering diameters between 0.4 and 23 μm obtained from these layers are juxtaposed with those obtained inside cloud veils around cumulonimbus (Cb) anvils and also with background aerosol measurements in the vicinity of the clouds. A significant number of particles with size diameters around 10 urn were detected inside these ultrathin subvisible cloud layers. The cloud particle size distribution closely resembles a background aerosol onto which a modal peak between 2 and 17 μm is superimposed. Measurements of particles with sizes above 23 μm could not be obtained since no suitable instrument was available on Geophysica. During the flight of 6 March 1999, upper tropospheric and lower stratospheric background aerosol was measured in the latitude band between 4°S and 19°S latitude. The resulting particle number densities along the 56th meridian exhibit very little latitudinal variation. The concentrations for particles with sizes above 0.5 μm encountered under these background conditions varied between 0.1 and 0.3 particles/cm3 of air in altitudes between 17 and 21 km. Copyright 2002 by the American Geophysical Union."
"7004884101;7406215388;7005490049;7402074810;","Use of two profilers during MCTEX for unambiguous identification of Bragg scattering and Rayleigh Scattering",1999,"10.1175/1520-0469(1999)056<3679:UOTPDM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033226574&doi=10.1175%2f1520-0469%281999%29056%3c3679%3aUOTPDM%3e2.0.CO%3b2&partnerID=40&md5=3a18f6ac817d63dacaf918c4e76a69e4","A 2835-MHz (10.6-cm wavelength) profiler and a 920-MHz (32.6-cm wavelength) profiler were collocated by the NOAA Aeronomy Laboratory at Garden Point, Australia, in the Tiwi Islands during the Maritime Continent Thunderstorm Experiment (MCTEX) field campaign in November and December 1995. The two profilers were directed vertically and observed vertical velocities in the clear atmosphere and hydrometeor fall velocities in deep precipitating cloud systems. In the absence of Rayleigh scatterers, the profilers obtain backscattering from the refractive index irregularities created from atmospheric turbulence acting upon refractive index gradients. This kind of scattering is commonly referred to as Bragg scattering and is only weakly dependent on the radar wavelength provided the radar half-wavelength lies within the inertial subrange of homogeneous, isotropic turbulence. In the presence of hydrometeors the profilers observe Rayleigh backscattering from hydrometeors much as weather radars do and this backscatter is very dependent upon radar wavelength, strongly favoring the shorter wavelength profiler resulting in a 20-dB enhancement of the ability of the 2835-MHz profiler to observe hydrometeors. This paper presents observations of equivalent reflectivity, Doppler velocity, and spectral width made by the collocated profilers during MCTEX. Differential reflectivity is used to diagnose the type of echo observed by the profilers in the spectral moment data. When precipitation or other particulate backscatter is dominant, the equivalent reflectivities are essentially the same for both profilers. When Bragg scattering is the dominant process, equivalent reflectivity observed by the 1-GHz profiler exceeds the equivalent reflectivity observed by the 3-GHz profiler by approximately 18 dBZe. However, when the 3-GHz profiler half-wavelength is smaller than the inner scale of turbulence, the equivalent reflectivity difference exceeds 18 dBZe, and when both Rayleigh scattering and Bragg scattering are observed simultaneously, the equivalent reflectivity difference is less than 18 dBZe. The results obtained confirm the capability of two collocated profilers to unambiguously identify the type of echo being observed and hence enable the segregation of ""clear air"" and precipitation echoes for studies of atmospheric dynamics and precipitating cloud systems."
"57193882808;","A parameterization of cloud microphysics for long-term cloud-resolving modeling of tropical convection",1999,"10.1016/S0169-8095(99)00029-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033429640&doi=10.1016%2fS0169-8095%2899%2900029-0&partnerID=40&md5=3fc725f6737357a8235769d154c1ab74","This paper documents development of a simple cloud microphysical parameterization for use in long-term cloud-resolving simulations of maritime tropical convection. The parameterization is based on the bulk approach and considers two classes of liquid water (cloud water and rain) and two classes of ice (slowly falling ice A and fast-falling ice B). Ice A represents unrimed or lightly rimed ice particles whose spectral characteristics are assumed to follow aircraft observations in tropical upper-tropospheric anvil clouds. Ice B, on the other hand, represents heavily rimed ice particles (e.g., graupel) which occur in the vicinity of convective towers. Mixing ratios for these four classes of cloud condensate are used as model variables. Together with the mixing ratio for water vapor, five field variables are used to represent all forms of water in the tropical atmosphere. The parameterization is used in a prescribed flow model to illustrate development of tropical convective and stratiform precipitation. Application of the parameterization to the cloud-resolving simulations of cloud systems observed during the TOGA COARE field campaign is also presented."
"23493093600;7201498455;7402760338;26428503000;56431832800;7007124673;55721771000;6602125464;","Achieving accuracy requirements for forest biomass mapping: A spaceborne data fusion method for estimating forest biomass and LiDAR sampling error",2013,"10.1016/j.rse.2012.11.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84871395709&doi=10.1016%2fj.rse.2012.11.016&partnerID=40&md5=8195523ce2a9d555feb18ad1f2ea76db","The synergistic use of active and passive remote sensing (i.e., data fusion) demonstrates the ability of spaceborne light detection and ranging (LiDAR), synthetic aperture radar (SAR) and multispectral imagery for achieving the accuracy requirements of a global forest biomass mapping mission (±20Mgha-1 or 20%, the greater of the two, for at least 80% of grid cells). A data fusion approach also provides a means to extend 3D information from discrete spaceborne LiDAR measurements of forest structure across scales much larger than that of the LiDAR footprint. For estimating biomass, these measurements mix a number of errors including those associated with LiDAR footprint sampling over regional-global extents. A general framework for mapping above ground live forest biomass density (AGB) with a data fusion approach is presented and verified using data from NASA field campaigns near Howland, ME, USA, to assess AGB and LiDAR sampling errors across a regionally representative landscape. We combined SAR and Landsat-derived optical (passive optical) image data to identify contiguous areas (&gt;0.5ha) that are relatively homogenous in remote sensing metrics (forest patches). We used this image-derived data with simulated spaceborne LiDAR derived from orbit and cloud cover simulations and airborne data from NASA's Laser Vegetation Imaging Sensor (LVIS) to compute AGB and estimate LiDAR sampling error for forest patches and 100m, 250m, 500m, and 1km grid cells. At both the patch and grid scales, we evaluated differences in AGB estimation and sampling error from the combined use of LiDAR with both SAR and passive optical and with either SAR or passive optical alone. First, this data fusion approach demonstrates that incorporating forest patches into the AGB mapping framework can provide sub-grid forest information for coarser grid-level AGB reporting. Second, a data fusion approach for estimating AGB using simulated spaceborne LiDAR with SAR and passive optical image combinations reduced forest AGB sampling errors 12%-38% from those where LiDAR is used with SAR or passive optical alone. In absolute terms, sampling errors were reduced from 14-40Mgha-1 to 11-28Mgha-1 across all grid scales and prediction methods, where minimum sampling errors were 11, 15, 18, and 22Mgha-1 for 1km, 500m, 250m, and 100m grid scales, respectively. Third, spaceborne global scale accuracy requirements were achieved whereby at least 80% of the grid cells at 100m, 250m, 500m, and 1km grid levels met AGB accuracy requirements using a combination of passive optical and SAR along with machine learning methods to predict vegetation structure metrics for forested areas without LiDAR samples. Finally, using either passive optical or SAR, accuracy requirements were met at the 500m and 250m grid level, respectively. © 2012 Elsevier Inc."
"11240127200;7003956042;14059648400;9337510800;56230578500;6506740413;6603931046;7402677913;35461763400;","Relationship between the NO2 photolysis frequency and the solar global irradiance",2009,"10.5194/amt-2-725-2009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952659971&doi=10.5194%2famt-2-725-2009&partnerID=40&md5=2149d35387fda9bbfd79d615fd54ef36","Representative values of the atmospheric NO2 photolysis frequency j(NO 2) are required for the adequate calculation and interpretation of NO and NO2 concentrations and exchange fluxes near the surface. Direct measurements of j(NO2) at ground level are often not available in field studies. In most cases, modeling approaches involving complex radiative transfer calculations are used to estimate j(NO2) and other photolysis frequencies for air chemistry studies. However, important input parameters for accurate modeling are often missing, most importantly with regard to the radiative effects of clouds. On the other hand, solar global irradiance (""global radiation"", G) is nowadays measured as a standard parameter in most field experiments and in many meteorological observation networks around the world. Previous studies mainly reported linear relationships between j(NO2) and G. We have measured j(NO2) using spectro- or filter radiometers and G using pyranometers side-by-side at several field sites. Our results cover a solar zenith angle range of 0-90°, and are based on nine field campaigns in temperate, subtropical and tropical environments during the period 1994-2008. We show that a second-order polynomial function (intercept Combining double low line 0): j(NO2) =(1+α)× (B 1×G+B2×G2), with α defined as the site-dependent UV-A surface albedo and the polynomial coefficients: B 1=(1.47± 0.03)×10-5 W-1 m 2 s-1 and B2=(-4.84±0.31)×10 -9 W-2 m4 s-1 can be used to estimate ground-level j(NO2) directly from G, independent of solar zenith angle under all atmospheric conditions. The absolute j(NO2) residual of the empirical function is ±6×10-4 s -1(2σ). The relationship is valid for sites below 800 m a.s.l. and with low surface albedo (α&lt;0.2). It is not valid in high mountains, above snow or ice and sandy or dry soil surfaces."
"6603714743;55950593000;7004296083;","Hygroscopic properties of nucleation mode and Aitken mode particles during nucleation bursts and in background air on the west coast of Ireland",2002,"10.1029/2000JD000176","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751290018&doi=10.1029%2f2000JD000176&partnerID=40&md5=3a91e9094fa49657da2c0ef6832f8215","The hygroscopic and cloud condensation nuclei (CCN) properties of submicrometer atmospheric aerosol particles were investigated using an Ultrafine Tandem Differential Mobility Analyzer (UF-TDMA) and a CCN counter at the Mace Head Monitoring Station on the west coast of Ireland during the New Particle Formation and Fate in the Coastal Environment (PARFORCE) field campaign in September 1998 and June 1999. These measurements give indirect in situ information on the composition and state of mixing of the aerosol particles. The UF-TDMA was used for monitoring of hygroscopic diameter growth factors of aerosol particles with dry mobility diameters 8-20 nm when taken from dry state to a controlled humid environment (RH 90%). The CCN counter was used to study the activation of aerosol particles when exposed to supersaturated conditions (dry diameters of 15-150 nm). It was seen that in clean marine air masses during the observed particle formation events, the newly formed nucleation mode particles (8 and 10 nm) most often had low growth factors (between 1.0 and 1.1) resulting from low solubility. This indicates that the nucleation mode particles consist of nonsoluble or weakly soluble species, possible accompanied by a small soluble part; however, when nucleation mode particles were observed outside the event periods, the growth factors were higher (about 1.3-1.4). In contrast, the 20 nm particles usually clearly belonged to the Aitken mode (based on number size distribution measurements) and had hygroscopic properties similar to some common salts (growth factors 1.4-1.5). Copyright 2002 by the American Geophysical Union."
"7103357902;23011242200;56594795400;23048575400;6507004778;55512417200;24448185400;7103204204;55883785100;25624725200;6603605070;54684233400;23492864500;7403401100;57192063986;7402538754;36659680800;12753020100;7201504886;7006415284;7005696579;7005174340;56363987000;8550791300;","The fine-scale structure of the trade wind cumuli over Barbados &ndash; An introduction to the CARRIBA project",2013,"10.5194/acp-13-10061-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885655357&doi=10.5194%2facp-13-10061-2013&partnerID=40&md5=744ce281ac1cab37d04687ccd88f2fca","The CARRIBA (Cloud, Aerosol, Radiation and tuRbulence in the trade wInd regime over BArbados) project, focused on high resolution and collocated measurements of thermodynamic, turbulent, microphysical, and radiative properties of trade wind cumuli over Barbados, is introduced. The project is based on two one-month field campaigns in November 2010 (climatic wet season) and April 2011 (climatic dry season). Observations are based on helicopter-borne and ground-based measurements in an area of 100 km2 off the coast of Barbados. CARRIBA is accompanied by long-term observations at the Barbados Cloud Observatory located at the East coast of Barbados since early in 2010 and which provides a longer-term context for the CARRIBA measurements. The deployed instrumentation and sampling strategy are presented together with a classification of the meteorological conditions. The two campaigns were influenced by different air masses advected from the Caribbean area, the Atlantic Ocean, and the African continent which led to distinct aerosol conditions. Pristine conditions with low aerosol particle number concentrations of ∼100 cm3 were alternating with periods influenced by Saharan dust or aerosol from biomass burning resulting in comparably high number concentrations of ∼ 500 cm3. The biomass burning aerosol was originating from both the Caribbean area and Africa. The shallow cumulus clouds responded to the different aerosol conditions with a wide range of mean droplet sizes and number concentrations. Two days with different aerosol and cloud microphysical properties but almost identical meteorological conditions have been analyzed in detail. The differences in the droplet number concentration and droplet sizes appear not to show any significant change for turbulent cloud mixing, but the relative roles of droplet inertia and sedimentation in initiating coalescence, as well as the cloud reflectivity, do change substantially. © Author(s) 2013."
"55802246600;8922308700;57193213111;","An investigation of the sub-grid variability of trace gases and aerosols for global climate modeling",2010,"10.5194/acp-10-6917-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955152884&doi=10.5194%2facp-10-6917-2010&partnerID=40&md5=9ffd8d8da8f7b003e2c9c567a86c08ec","One fundamental property and limitation of grid based models is their inability to identify spatial details smaller than the grid cell size. While decades of work have gone into developing sub-grid treatments for clouds and land surface processes in climate models, the quantitative understanding of sub-grid processes and variability for aerosols and their precursors is much poorer. In this study, WRF-Chem is used to simulate the trace gases and aerosols over central Mexico during the 2006 MILAGRO field campaign, with multiple spatial resolutions and emission/terrain scenarios. Our analysis focuses on quantifying the sub-grid variability (SGV) of trace gases and aerosols within a typical global climate model grid cell, i.e. 75&times;75 km2. <br><br> Our results suggest that a simulation with 3-km horizontal grid spacing adequately reproduces the overall transport and mixing of trace gases and aerosols downwind of Mexico City, while 75-km horizontal grid spacing is insufficient to represent local emission and terrain-induced flows along the mountain ridge, subsequently affecting the transport and mixing of plumes from nearby sources. Therefore, the coarse model grid cell average may not correctly represent aerosol properties measured over polluted areas. Probability density functions (PDFs) for trace gases and aerosols show that secondary trace gases and aerosols, such as O3, sulfate, ammonium, and nitrate, are more likely to have a relatively uniform probability distribution (i.e. smaller SGV) over a narrow range of concentration values. Mostly inert and long-lived trace gases and aerosols, such as CO and BC, are more likely to have broad and skewed distributions (i.e. larger SGV) over polluted regions. Over remote areas, all trace gases and aerosols are more uniformly distributed compared to polluted areas. Both CO and O3 SGV vertical profiles are nearly constant within the PBL during daytime, indicating that trace gases are very efficiently transported and mixed vertically by turbulence. But, simulated horizontal variability indicates that trace gases and aerosols are not well mixed horizontally in the PBL. During nighttime the SGV for trace gases is maximum at the surface, and quickly decreases with height. Unlike the trace gases, the SGV of BC and secondary aerosols reaches a maximum at the PBL top during the day. The SGV decreases with distance away from the polluted urban area, has a more rapid decrease for long-lived trace gases and aerosols than for secondary ones, and is greater during daytime than nighttime. <br><br> The SGV of trace gases and aerosols is generally larger than for meteorological quantities. Emissions can account for up to 50% of the SGV over urban areas such as Mexico City during daytime for less-reactive trace gases and aerosols, such as CO and BC. The impact of emission spatial variability on SGV decays with altitude in the PBL and is insignificant in the free troposphere. The emission variability affects SGV more significantly during daytime (rather than nighttime) and over urban (rather than rural or remote) areas. The terrain, through its impact on meteorological fields such as wind and the PBL structure, affects dispersion and transport of trace gases and aerosols and their SGV. © Author(s) 2010."
"6602412038;56260361500;55954833500;56506988700;7102816537;","Phenols and nitrated phenols in clouds at Mount Brocken",1999,"10.1080/03067319908031417","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037874030&doi=10.1080%2f03067319908031417&partnerID=40&md5=cb635a14be12a8c6559b8a4773da07a4","Two phenols and four nitrophenols have been determined in the gas and liquid phase of clouds during a field campaign in May 1994 at Mount Brocken (Germany). If the total amount in both phases is considered, 2-nitrophenol is the dominant compound which is mainly present in the gas phase while 4-nitrophenol is much more abundant in the liquid phase, which reflects the differences in the distribution constants. The experimental data suggest that mononitrophenols may partially originate from automobile exhaust while dinitrophenols are almost completely formed by atmospheric reactions. Furthermore, comparison of the concentration of dinitrophenols and the extent to which air masses are transported in clouds indicates that these compounds are mainly formed in cloud droplets.Two phenols and four nitrophenols have been determined in the gas and liquid phase of clouds during a field campaign in May 1994 at Mount Brocken (Germany). If the total amount in both phases is considered, 2-nitrophenol is the dominant compound which is mainly present in the gas phase while 4-nitrophenol is much more abundant in the liquid phase, which reflects the differences in the distribution constants. The experimental data suggest that mononitrophenols may partially originate from automobile exhaust while dinitrophenols are almost completely formed by atmospheric reactions. Furthermore, comparison of the concentration of dinitrophenols and the extent to which air masses are transported in clouds indicates that these compounds are mainly formed in cloud droplets."
"55481275400;16308514000;57198267998;54784169900;7101846027;","Impact of emissions from shipping, land, and the ocean on stratocumulus cloud water elemental composition during the 2011 E-PEACE field campaign",2014,"10.1016/j.atmosenv.2014.01.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896008652&doi=10.1016%2fj.atmosenv.2014.01.020&partnerID=40&md5=0df0ad9f0182561ca66542aaef2be0ad","This study reports on cloud water chemical and pH measurements off the California coast during the July-August 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). Eighty two cloud water samples were collected by a slotted-rod cloud water collector protruding above the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter in boundary layer stratocumulus clouds impacted to varying degrees by ocean-derived emissions, ship exhaust, and land emissions. Cloud water pH ranged between 2.92 and 7.58, with an average of 4.46. Peak pH values were observed north of San Francisco, simultaneous with the highest concentrations of Si, B, and Cs, and air masses originating over land. The lowest pH values were observed south of San Francisco due to ship emissions resulting in the highest concentrations of sulfate, nitrate, V, Fe, Al, P, Cd, Ti, Sb, P, and Mn. Many of these species act as important agents in aqueous-phase reactions in cloud drops and are critical ocean micronutrients after subsequent wet deposition in an ocean system that can be nutrient-limited. E-PEACE measurements suggest that conditions in the California coastal zone region can promote the conversion of micronutrients to more soluble forms, if they are not already, due to acidic cloud water conditions, the ubiquity of important organic agents such as oxalic acid, and the persistence of stratocumulus clouds to allow for continuous cloud processing. © 2014 Elsevier Ltd."
"54395555200;","An investigation of composite dropsonde profiles for developing and nondeveloping tropical waves during the 2010 PREDICT field campaign",2013,"10.1175/JAS-D-12-052.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874984917&doi=10.1175%2fJAS-D-12-052.1&partnerID=40&md5=9ac1cd02f8fc90d2dd9983613d80b6d8","Composite dropsonde profiles are analyzed for developing and nondeveloping tropical waves in an attempt to improve the understanding of tropical cyclogenesis. These tropical waves were sampled by 25 reconnaissance missions during the 2010 Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) field campaign. Comparisons are made between mean profiles of temperature, mixing ratio, relative humidity, radial and tangential winds, relative vorticity, and virtual convective available potential energy (CAPE) for genesis and nongenesis cases. Genesis soundings are further analyzed in temporal progression to investigate whether significant changes in the thermodynamic or wind fields occur during the transition from tropical wave to tropical cyclone. Significant results include the development of positive temperature anomalies from 500 to 200 hPa 2 days prior to genesis in developing waves. This is not observed in the nongenesis mean. Progressive mesoscale moistening of the column is observed within 150 km of the center of circulation prior to genesis. The genesis composite is found to be significantly moister than the nongenesis composite at the middle levels, while comparatively drier at low levels, suggesting that dry air is more detrimental to genesis when located at the middle levels. Time-varying tangential wind profiles reveal an initial delay in intensification, followed by an increase in organization 24 h pregenesis. The vertical evolution of relative vorticity, in addition to a warmover-cold thermal structure, is more consistent with a top-down than a bottom-up genesis mechanism. Last, CAPE values are much greater for nongenesis than genesis profiles, indicating that greater instability does not necessarily favor genesis. ©2013 American Meteorological Society."
"35419152500;12796056300;36673860300;14122622000;8217910800;36059883200;7202577029;7202582283;35762232300;15318911400;7004210193;6506735411;7003877353;7201898106;7006134094;8764227000;6603955469;","Airborne and ground-based measurements using a high-performance raman lidar",2010,"10.1175/2010JTECHA1391.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78649434662&doi=10.1175%2f2010JTECHA1391.1&partnerID=40&md5=a21be5daf476e66a1908fc750fa53b16","A high-performance Raman lidar operating in the UV portion of the spectrum has been used to acquire, for the first time using a single lidar, simultaneous airborne profiles of the water vapor mixing ratio, aerosol backscatter, aerosol extinction, aerosol depolarization and research mode measurements of cloud liquid water, cloud droplet radius, and number density. The Raman Airborne Spectroscopic Lidar (RASL) system was installed in a Beechcraft King Air B200 aircraft and was flown over the mid-Atlantic United States during July-August 2007 at altitudes ranging between 5 and 8 km. During these flights, despite suboptimal laser performance and subaperture use of the telescope, all RASL measurement expectations were met, except that of aerosol extinction. Following the Water Vapor Validation Experiment-Satellite/Sondes (WAVES_2007) field campaign in the summer of 2007, RASL was installed in a mobile trailer for ground-based use during the Measurements of Humidity and Validation Experiment (MOHAVE-II) field campaign held during October 2007 at the Jet Propulsion Laboratory's Table Mountain Facility in southern California. This ground-based configuration of the lidar hardware is called Atmospheric Lidar for Validation, Interagency Collaboration and Education (ALVICE). During the MOHAVE-II field campaign, during which only nighttime measurements were made, ALVICE demonstrated significant sensitivity to lower-stratospheric water vapor. Numerical simulation and comparisons with a cryogenic frost-point hygrometer are used to demonstrate that a system with the performance characteristics of RASL-ALVICE should indeed be able to quantify water vapor well into the lower stratosphere with extended averaging from an elevated location like Table Mountain. The same design considerations that optimize Raman lidar for airborne use on a small research aircraft are, therefore, shown to yield significant dividends in the quantification of lower-stratospheric water vapor. The MOHAVE-II measurements, along with numerical simulation, were used to determine that the likely reason for the suboptimal airborne aerosol extinction performance during the WAVES_2007 campaign was a misaligned interference filter. With full laser power and a properly tuned interference filter, RASL is shown to be capable of measuring the main water vapor and aerosol parameters with temporal resolutions of between 2 and 45 s and spatial resolutions ranging from 30 to 330 m from a flight altitude of 8 km with precision of generally less than 10%, providing performance that is competitive with some airborne Differential Absorption Lidar (DIAL) water vapor and High Spectral Resolution Lidar (HSRL) aerosol instruments. The use of diode-pumped laser technology would improve the performance of an airborne Raman lidar and permit additional instrumentation to be carried on board a small research aircraft. The combined airborne and ground-based measurements presented here demonstratea level of versatility in Raman lidar that may be impossible to duplicate with any other single lidar technique. © 2010 American Meteorological Society."
"7006450978;57196706568;56308509200;35618476300;7202957110;6506986083;6701409929;","Lightning characteristics observed by a VLF/LF lightning detection network (LINET) in Brazil, Australia, Africa and Germany",2009,"10.5194/acp-9-7795-2009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77950450569&doi=10.5194%2facp-9-7795-2009&partnerID=40&md5=1d9121602fe9550c16d4376851434d72","This paper describes lightning characteristics as obtained in four sets of lightning measurements during recent field campaigns in different parts of the world from mid-latitudes to the tropics by the novel VLF/LF (very low frequency/low frequency) lightning detection network (LINET). The paper gives a general overview on the approach, and a synopsis of the statistical results for the observation periods as a whole and for one special day in each region. The focus is on the characteristics of lightning which can specifically be observed by this system like intra-cloud and cloud-to-ground stroke statistics, vertical distributions of intra-cloud strokes or peak current distributions. Some conclusions regarding lightning produced NOx are also presented as this was one of the aims of the tropical field campaigns TROCCINOX (Tropical Convection, Cirrus and Nitrogen Oxides Experiment) and TroCCiBras (Tropical Convection and Cirrus Experiment Brazil) in Brazil during January/February 2005, SCOUTO3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) and TWP-ICE (Tropical Warm Pool-International Cloud Experiment) during November/December 2005 and January/February 2006, respectively, in the Darwin area in N-Australia, and of AMMA (African Monsoon Multidisciplinary Analyses) in W-Africa during June-November 2006."
"7102018821;25227357000;7005528388;7004242319;","On the correlation between ice water content and ice crystal size and its application to radiative transfer and general circulation models",2008,"10.1029/2008GL033918","https://www.scopus.com/inward/record.uri?eid=2-s2.0-53749083037&doi=10.1029%2f2008GL033918&partnerID=40&md5=9035c0e0b194282fd4ee33268635ec8d","We performed correlation analysis involving ice water content (IWC) and mean effective ice crystal size (De) intended for application to climate models. For this purpose, ice crystal size distributions obtained from in situ measurements conducted from numerous field campaigns in the tropics, midlatitude, and Arctic regions were used and we show that IWC and De are well-correlated in this regional division. Including temperature classification in midlatitude cases increases this correlation. We applied the correlation results to cloud radiative forcing calculations in terms of IWC, in which De is expressed as a baseline mean and deviation from uncertainty in small ice crystal measurements. The latter deviates from the mean by less than 2 W/m2 in net radiative forcing. Using the correlation results, simulations from the UCLA GCM showed substantial regional deviations in OLR and precipitation patterns from assuming a constant De. Copyright 2008 by the American Geophysical Union."
"55819208800;7006072255;6701590980;23995016900;6603770689;8581428600;6602121676;7006711117;7406419945;6603792921;7403331283;","The cumulus, photogrammetric, in situ, and Doppler Observations Experiment of 2006",2008,"10.1175/BAMS-89-1-57","https://www.scopus.com/inward/record.uri?eid=2-s2.0-41849101035&doi=10.1175%2fBAMS-89-1-57&partnerID=40&md5=b2dd1000147630013d23cc34ad5910b0","The finescale structure and dynamics of cumulus, evolving from shallow to deep convection, and the accompanying changes in the environment and boundary layer over mountainous terrain were the subjects of a field campaign in July-August 2006. Few measurements exist of the transport of boundary layer air into the deep troposphere by the orographic toroidal circulation and orographic convection. The campaign was conducted over the Santa Catalina Mountains in southern Arizona, a natural laboratory to study convection, given the spatially and temporally regular development of cumulus driven by elevated heating and convergent boundary layer flow. Cumuli and their environment were sampled via coordinated observations from the surface, radiosonde balloons, and aircraft, along with airborne radar data and stereophotogrammetry from two angles. The collected dataset is expected to yield new insights in the boundary layer processes leading to orographic convection, in the cumulus-induced transport of boundary layer air into the troposphere, and in fundamental cumulus dynamics. This article summarizes the motivations, objectives, experimental strategies, preliminary findings, and the potential research paths stirred by the project. © 2008 American Meteorological Society."
"7402883020;7401850582;35263854800;7102336894;57217801354;7202985280;57218357458;7404611595;35396858200;26028515700;57211052287;8359591200;7006372688;57217429902;7003468369;7005423580;57203052274;26643054400;7004185679;8937902100;57209337154;57136469800;7005913300;7404462897;57212815233;56187540500;","Testing fast photochemical theory during TRACE-P based on measurements of OH, HO2 and CH2O",2004,"10.1029/2003JD004278","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6444219977&doi=10.1029%2f2003JD004278&partnerID=40&md5=461a384797dda384accf65bd33690cf1","Measurements of several short-lived photochemical species (e.g., OH, HO2, and CH2O) were obtained from the DC-8 and P3-B aircraft during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) campaign. To assess fast photochemical theory over the east Asian coast and western Pacific, these measurements are compared to predictions using a photochemical time-dependent box model constrained by coincident measurements of long-lived tracers and physical parameters. Both OH and HO2 are generally overpredicted by the model throughout the troposphere, which is a different result from previous field campaigns. The calculated-to-observed ratio of OH shows an altitude trend, with OH overpredicted by 80% in the upper troposphere and by 40-60% in the middle troposphere. Boundary layer and lower tropospheric OH ratios decrease from middle tropospheric values to 1.07 for the DC-8 and to 0.70 for the P3-B. HO2 measured on the DC-8 is overpredicted by a median of 23% and shows no trend in the agreement with altitude. Three subsets of data which compose 12% of the HO2 measurements represent outliers with respect to calculated-to-observed ratios: stratospherically influenced air, upper tropospheric data with NO &gt; 135 pptv, and data from within clouds. Pronounced underpredictions of both HO2 and OH were found for stratospherically influenced air, which is in contrast to previous studies showing good agreement of predicted and observed HOx, in the stratosphere. Observational evidence of heterogeneous uptake of HO2 within low and middle tropospheric clouds is presented, though there is no indication of significant HO2 uptake within higher-altitude clouds. Model predictions of CH2O are in good agreement with observations in the median for background concentrations, but a large scatter exists. Factors contributing to this scatter are examined, including the limited availability of some important constraining measurements, particularly CH3OOH. Some high concentrations of CH2O near the coast are underpredicted by the box model as a result of the inherent neglect of transport effects of CH2O and its precursors via the steady state assumption; however, these occurrences are limited to ∼1% of the data. For the vast majority of the atmosphere, transport is unimportant in the budget of CH2O, which may be considered to be in steady state. Copyright 2004 by the American Geophysical Union."
"23670554500;55479830300;35203962800;36723129700;7801565183;7005069415;6701772538;7102011023;6505942213;6602446468;36124109400;45761471600;36154519800;14819932100;7006434689;","Spatial variation of aerosol optical properties around the high-alpine site Jungfraujoch (3580 m a.s.l.)",2012,"10.5194/acp-12-7231-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84869074633&doi=10.5194%2facp-12-7231-2012&partnerID=40&md5=190df8eea0915512809cb6e30de39735","This paper presents results of the extensive field campaign CLACE 2010 (Cloud and Aerosol Characterization Experiment) performed in summer 2010 at the Jungfraujoch (JFJ) and the Kleine Scheidegg (KLS) in the Swiss Alps. The main goal of this campaign was to investigate the vertical variability of aerosol optical properties around the JFJ and to show the consistency of the different employed measurement techniques considering explicitly the effects of relative humidity (RH) on the aerosol light scattering. Various aerosol optical and microphysical parameters were recorded using in-situ and remote sensing techniques. In-situ measurements of aerosol size distribution, light scattering, light absorption and scattering enhancement due to water uptake were performed at the JFJ at 3580 m a.s.l.. A unique set-up allowed remote sensing measurements of aerosol columnar and vertical properties from the KLS located about 1500 m below and within the line of sight to the JFJ (horizontal distance of approx. 4.5 km). In addition, two satellite retrievals from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) and the Moderate Resolution Imaging Spectroradiometer (MODIS) as well as back trajectory analyses were added to the comparison to account for a wider geographical context. All in-situ and remote sensing measurements were in clear correspondence. The ambient extinction coefficient measured in situ at the JFJ agreed well with the KLS-based LIDAR (Light Detection and Ranging) retrieval at the altitude-level of the JFJ under plausible assumptions on the LIDAR ratio. However, we can show that the quality of this comparison is affected by orographic effects due to the exposed location of the JFJ on a saddle between two mountains and next to a large glacier. The local RH around the JFJ was often higher than in the optical path of the LIDAR measurement, especially when the wind originated from the south via the glacier, leading to orographic clouds which remained lower than the LIDAR beam. Furthermore, the dominance of long-range transported Saharan dust was observed in all measurements for several days, however only for a shorter time period in the in-situ measurements due to the vertical structure of the dust plume. The optical properties of the aerosol column retrieved from SEVIRI and MODIS showed the same magnitude and a similar temporal evolution as the measurements at the KLS and the JFJ. Remaining differences are attributed to the complex terrain and simplifications in the aerosol retrieval scheme in general. © 2012 Author(s)."
"6603944055;6602574676;7201463831;7202948585;6602137800;7401844779;35468686100;8850861200;6603689866;36098286300;57206332144;57200082194;7004208584;35546736600;26643251000;","Analysis of snow bidirectional reflectance from ARCTAS spring-2008 campaign",2010,"10.5194/acp-10-4359-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952416664&doi=10.5194%2facp-10-4359-2010&partnerID=40&md5=18f9ff9f61ba7801e96b452a21370982","The spring 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment was one of major intensive field campaigns of the International Polar Year aimed at detailed characterization of atmospheric physical and chemical processes in the Arctic region. A part of this campaign was a unique snow bidirectional reflectance experiment on the NASA P-3B aircraft conducted on 7 and 15 April by the Cloud Absorption Radiometer (CAR) jointly with airborne Ames Airborne Tracking Sunphotometer (AATS) and ground-based Aerosol Robotic Network (AERONET) sunphotometers. The CAR data were atmospherically corrected to derive snow bidirectional reflectance at high 1° angular resolution in view zenith and azimuthal angles along with surface albedo. The derived albedo was generally in good agreement with ground albedo measurements collected on 15 April. The CAR snow bidirectional reflectance factor (BRF) was used to study the accuracy of analytical Ross-Thick Li-Sparse (RTLS), Modified Rahman-Pinty-Verstraete (MRPV) and Asymptotic Analytical Radiative Transfer (AART) BRF models. Except for the glint region (azimuthal angles φ ≤ 40°), the best fit MRPV and RTLS models fit snow BRF to within ±0.05. The plane-parallel radiative transfer (PPRT) solution was also analyzed with the models of spheres, spheroids, randomly oriented fractal crystals, and with a synthetic phase function. The latter merged the model of spheroids for the forward scattering angles with the fractal model in the backscattering direction. The PPRT solution with synthetic phase function provided the best fit to measured BRF in the full range of angles. Regardless of the snow grain shape, the PPRT model significantly over-/underestimated snow BRF in the glint/backscattering regions, respectively, which agrees with other studies. To improve agreement with experiment, we introduced a model of macroscopic snow surface roughness by averaging the PPRT solution over the slope distribution function and by adding a simple model of shadows. With macroscopic roughness described by two parameters, the AART model achieved an accuracy of about ±0.05 with a possible bias of ±0.03 in the spectral range 0.4-2.2 μm. This high accuracy holds at view zenith angles below 55-60° covering the practically important range for remote sensing applications, and includes both glint and backscattering directions. © Author(s) 2010."
"7004057920;7006675203;7101959253;","Validation of surface retrieved cloud optical properties with in situ measurements at the Atmospheric Radiation Measurement Program (ARM) South Great Plains site",2003,"10.1029/2003jd003385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1442289308&doi=10.1029%2f2003jd003385&partnerID=40&md5=679c2ff204b8e160ab22788bbc2ff44b","Cloud optical properties inferred from a multifilter rotating shadowband radiometer have been validated against in situ measurements during the second ARM Enhanced Shortwave Experiment (ARESE II) field campaign at the ARM South Great Plains (SGP) site. On the basis of eight aircraft in situ vertical profiles (constructed from measurements), Forward Spectra Scattering Probe (FSSP), we find that our retrieved cloud effective radii for single-layer warm water clouds agree well with in situ measurements, within 5.5%. A sensitivity study also illustrates that (for this case) a 13% uncertainty in observed liquid water path (LWP, 20 g/m2) results in 1.5% difference in retrieved cloud optical depth and 12.7% difference in inferred cloud effective radius, on average. The uncertainty of the LWP measured by the microwave radiometer (MWR) is the major contributor to the uncertainty of retrieved cloud effective radius. Further, we conclude that the uncertainty of our inferred cloud optical properties is better than 5% for warm water clouds based on a surface closure study, in which cloud optical properties inferred from narrowband irradiances are applied to a shortwave model and the modeled broadband fluxes are compared to a surface pyranometer. Copyright 2003 by the American Geophysical Union."
"7005228119;6603689866;57210169776;7201789296;7202801045;6602826769;","Spectral reflectance of melting snow in a high Arctic watershed on Svalbard: Some implications for optical satellite remote sensing studies",1999,"10.1002/(SICI)1099-1085(199909)13:12/13<2033::AID-HYP892>3.0.CO;2-M","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033190477&doi=10.1002%2f%28SICI%291099-1085%28199909%2913%3a12%2f13%3c2033%3a%3aAID-HYP892%3e3.0.CO%3b2-M&partnerID=40&md5=4401c10be7d52492ed08bb93773e014b","Field campaigns were undertaken in May and June of 1992 and 1997 in order to study spectral reflectance characteristics of snow during melt-off. The investigations were performed on snow-covered tundra at Ny-Alesund, Svalbard (79°N). Spectral measurements were acquired with spectroradiometers covering wavelengths from 350 to 2500 nm. Supporting measurements such as snow thickness, density, content of liquid water, grain size and shape, stratification of snowpack, as well as cloud observations and air temperature, were monitored throughout the field campaigns. Spectral measurements demonstrate that the near-infrared albedo is most affected by the ongoing snow metamorphism while the albedo in the visible wavelength range is more strongly affected by surface pollution. Comparisons of spectral measurements and spectrally integrated measurements emphasize the need for narrow-band to broad-band conversion when applying satellite-derived albedo to surface energy-balance calculations. As an example, Landsat TM Band 4 albedo is shown to produce slightly high albedo values compared to spectrally integrated albedo (285-2800 nm). Daily albedo measurements from 1981-1997 show that the albedo normally drops from 80% to bare ground levels (approx. 10%) within two to four weeks and the date when the tundra becomes snow-free varies from early June to early July. Thus, the changing spectral characteristics of snow during melt-off combined with a general rapid decrease in albedo call for cautions use of satellite-derived albedo, especially when used as absolute numbers. Our data also illustrate the effect of cloud cover on surface albedo for an event in which the integrated albedo increased by 7% under cloudy conditions compared to clear skies without changes of surface properties. Finally, the reflectance of snow increase relative to nadir for measurements facing the sun and at azimuths 90° and 180° by 8, 15, 19, and 26% for viewing angles 15°, 30°, 45°, and 60°, respectively, due to anisotropic reflection.Field campaigns were undertaken in May and June of 1992 and 1997 in order to study spectral reflectance characteristics of snow during melt-off. The investigations were performed on snow-covered tundra at Ny-Alesund, Svalbard (79°N). Spectral measurements were acquired with spectroradiometers covering wavelengths from 350 to 2500 nm. Supporting measurements such as snow thickness, density, content of liquid water, grain size and shape, stratification of snowpack, as well as cloud observations and air temperature, were monitored throughout the field campaigns. Spectral measurements demonstrate that the near-infrared albedo is most affected by the ongoing snow metamorphism while the albedo in the visible wavelength range is more strongly affected by surface pollution. Comparisons of spectral measurements and spectrally integrated measurements emphasize the need for narrow-band to broad-band conversion when applying satellite-derived albedo to surface energy-balance calculations. As an example, Landsat TM Band 4 albedo is shown to produce slightly high albedo values compared to the spectrally integrated albedo (285-2800 nm). Daily albedo measurements from 1981-1997 show that the albedo normally drops from 80% to bare ground levels (~10%) within two to four weeks and the date when the tundra becomes snow-free varies from early June to early July. Thus, the changing spectral characteristics of snow during melt-off combined with a general rapid decrease in albedo call for cautious use of satellite-derived albedo, especially when used as absolute numbers. Our data also illustrate the effect of cloud cover on surface albedo for an event in which the integrated albedo increased by 7% under cloudy conditions compared to clear skies without changes of surface properties. Finally, the reflectance of snow increases relative to nadir for measurements facing the sun and at azimuths 90°and 180°by 8, 15, 19, and 26% for viewing angles 15°, 30°, 45°, and 60°, respectively, due to anisotropic reflection."
"35509639400;7201504886;16444240700;24723648200;56212055700;6603868770;23017945100;7006184606;55883785100;35551238800;22133985200;57206156792;6603418610;57202531041;23492864500;55940978200;23768540500;6603566335;6602115663;56198145500;35621058500;56567409000;57190209035;7201423091;","EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation",2017,"10.1007/s10712-017-9428-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030099198&doi=10.1007%2fs10712-017-9428-0&partnerID=40&md5=df9180e49db240179718c7784676b9d6","Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization. © 2017, The Author(s)."
"6602999057;56522444900;55554574300;57195682350;56682130400;57217801354;35551238800;15319055900;13906443400;7006424590;9536598800;25958833500;57195685805;56073196800;57195676863;56993642000;57195542625;57195683987;57195673296;55226243300;57195675085;","A meteorological and chemical overview of the DACCIWA field campaign in West Africa in June-July 2016",2017,"10.5194/acp-17-10893-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029542737&doi=10.5194%2facp-17-10893-2017&partnerID=40&md5=e27813bffb55d6d1e061df14a953d3d9","In June and July 2016 the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project organised a major international field campaign in southern West Africa (SWA) including measurements from three inland ground supersites, urban sites in Cotonou and Abidjan, radiosondes, and three research aircraft. A significant range of different weather situations were encountered during this period, including the monsoon onset. The purpose of this paper is to characterise the large-scale setting for the campaign as well as synoptic and mesoscale weather systems affecting the study region in the light of existing conceptual ideas, mainly using objective and subjective identification algorithms based on (re-)analysis and satellite products. In addition, it is shown how the described synoptic variations influence the atmospheric composition over SWA through advection of mineral dust, biomass burning and urban pollution plumes. The boreal summer of 2016 was characterised by Pacific La Niña, Atlantic El Niño and warm eastern Mediterranean conditions, whose competing influences on precipitation led to an overall average rainy season. During the relatively dusty pre-onset Phase 1 (1-21 June 2016), three westward-propagating coherent cyclonic vortices between 4 and 13° N modulated winds and rainfall in the Guinea coastal area. The monsoon onset occurred in connection with a marked extratropical trough and cold surge over northern Africa, leading to a breakdown of the Saharan heat low and African easterly jet and a suppression of rainfall. During this period, quasi-stationary low-level vortices associated with the trough transformed into more tropical, propagating disturbances resembling an African easterly wave (AEW). To the east of this system, moist southerlies penetrated deep into the continent. The post-onset Phase 2 (22 June-20 July 2016) was characterised by a significant increase in low-level cloudiness, unusually dry conditions and strong northeastward dispersion of urban pollution plumes in SWA as well as rainfall modulation by westward-propagating AEWs in the Sahel. Around 12-14 July 2016 an interesting and so-far undocumented cyclonic-anticyclonic vortex couplet crossed SWA. The anticyclonic centre had its origin in the Southern Hemisphere and transported unusually dry air filled with aged aerosol into the region. During Phase 3 (21-26 July 2016), a similar vortex couplet slightly farther north created enhanced westerly moisture transports into SWA and extraordinarily wet conditions, accompanied by a deep penetration of the biomass burning plume from central Africa. Finally, a return to more undisturbed monsoon conditions took place during Phase 4 (27-31 July 2016). The in-depth synoptic analysis reveals that several significant weather systems during the DACCIWA campaign cannot be attributed unequivocally to any of the tropical waves and disturbances described in the literature and thus deserve further study. © 2017 Author(s)."
"16642991200;7003414581;","Potential of polarization lidar to provide profiles of CCN-and INP-relevant aerosol parameters",2016,"10.5194/acp-16-5905-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969883827&doi=10.5194%2facp-16-5905-2016&partnerID=40&md5=a9fbcef4bc4e11aba2b42e1757cbcc18","We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN) and ice nucleating particle (INP) number concentrations can be estimated. We show that height profiles of particle number concentrations n50, dry considering dry aerosol particles with radius &gt; 50 nm (reservoir of CCN in the case of marine and continental non-desert aerosols), n100, dry (particles with dry radius &gt; 100 nm, reservoir of desert dust CCN), and of n250, dry (particles with dry radius &gt; 250 nm, reservoir of favorable INP), as well as profiles of the particle surface area concentration sdry (used in INP parameterizations) can be retrieved from lidar-derived aerosol extinction coefficients σ with relative uncertainties of a factor of 1.5-2 in the case of n50, dry and n100, dry and of about 25-50% in the case of n250, dry and sdry. Of key importance is the potential of polarization lidar to distinguish and separate the optical properties of desert aerosols from non-desert aerosol such as continental and marine particles. We investigate the relationship between σ, measured at ambient atmospheric conditions, and n50, dry for marine and continental aerosols, n100, dry for desert dust particles, and n250, dry and sdry for three aerosol types (desert, non-desert continental, marine) and for the main lidar wavelengths of 355, 532, and 1064 nm. Our study is based on multiyear Aerosol Robotic Network (AERONET) photometer observations of aerosol optical thickness and column-integrated particle size distribution at Leipzig, Germany, and Limassol, Cyprus, which cover all realistic aerosol mixtures. We further include AERONET data from field campaigns in Morocco, Cabo Verde, and Barbados, which provide pure dust and pure marine aerosol scenarios. By means of a simple CCN parameterization (with n50, dry or n100, dry as input) and available INP parameterization schemes (with n250, dry and sdry as input) we finally compute profiles of the CCN-relevant particle number concentration nCCN and the INP number concentration nINP. We apply the method to a lidar observation of a heavy dust outbreak crossing Cyprus and a case dominated by continental aerosol pollution. © 2016 Author(s)."
"55350802700;56210720700;37261739700;6701753599;23989889000;16834406100;18134565600;35396858200;8113018100;18438062100;24477694300;57189389471;15080710300;57203776263;7005891596;6603178707;6602356428;16308514000;","Airborne characterization of subsaturated aerosol hygroscopicity and dry refractive index from the surface to 6.5km during the SEAC4RS campaign",2016,"10.1002/2015JD024498","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969981541&doi=10.1002%2f2015JD024498&partnerID=40&md5=92652ff0dbe538eeb361c99eb8ef6a98","In situ aerosol particle measurements were conducted during 21 NASA DC-8 flights in the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys field campaign over the United States, Canada, Pacific Ocean, and Gulf ofMexico. For the first time, this study reports rapid, size-resolved hygroscopic growth and real refractive index (RI at 532nm) data between the surface and upper troposphere in a variety of air masses including wildfires, agricultural fires, biogenic, marine, and urban outflow. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) quantified size-resolved diameter growth factors (GF =Dp,wet/Dp,dry) that are used to infer the hygroscopicity parameter κ. Thermokinetic simulations were conducted to estimate the impact of partial particle volatilization within the DASH-SP across a range of sampling conditions. Analyses of GF and RI data as a function of air mass origin, dry size, and altitude are reported, in addition to κ values for the inorganic and organic fractions of aerosol. Average RI values are found to be fairly constant (1.52–1.54) for all air mass categories. An algorithm is used to compare size-resolved DASH-SP GF with bulk scattering f(RH= 80%) data obtained froma pair of nephelometers, and the results show that the two can only be reconciled if GF is assumed to decrease with increasing dry size above 400nm (i.e., beyond the upper bound of DASH-SP measurements). Individual case studies illustrate variations of hygroscopicity as a function of dry size, environmental conditions, altitude, and composition. © 2016. American Geophysical Union. All Rights Reserved."
"7003510880;26422803600;35326039600;57219982231;26423400900;6602497877;56087850300;22953390300;55524267300;35313939900;35276889200;8618154900;6506355037;7004427005;7003696133;","KITcube - A mobile observation platform for convection studies deployed during HyMeX",2013,"10.1127/0941-2948/2013/0542","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897061937&doi=10.1127%2f0941-2948%2f2013%2f0542&partnerID=40&md5=f5ffa90f14a277f6ffc181cbd0592dc7","With the increase of spatial resolution of weather forecast models to order O(1 km), the need for adequate observations for model validation becomes evident. Therefore, we designed and constructed the ''KITcube'', a mobile observation platform for convection studies of processes on the meso-γ scale. The KITcube consists of in-situ and remote sensing systems which allow measuring the energy balance components of the Earth's surface at different sites; the mean atmospheric conditions by radiosondes, GPS station, and a microwave radiometer; the turbulent characteristics by a sodar and wind lidars; and cloud and precipitation properties by use of a cloud radar, a micro rain radar, disdrometers, rain gauges, and an X-band rain radar. The KITcube was deployed fully for the first time on the French island of Corsica during the HyMeX (Hydrological cycle in the Mediterranean eXperiment) field campaign in 2012. In this article, the components of KITcube and its implementation on the island are described. Moreover, results from one of the HyMeX intensive observation periods are presented to show the capabilities of KITcube. © Gebrüder Borntraeger, Stuttgart 2013."
"7004057920;57201726470;56521864800;55510976200;54783781000;7005862399;26643510900;36076994600;57203798762;","Comparison of MODIS cloud microphysical properties with in-situ measurements over the Southeast Pacific",2012,"10.5194/acp-12-11261-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870538467&doi=10.5194%2facp-12-11261-2012&partnerID=40&md5=fa12b9d4f7db3f6169d2bd9c75947aac","Utilizing the unique characteristics of the cloud over the Southeast Pacific (SEP) off the coast of Chile during the VOCALS field campaign, we compared satellite remote sensing of cloud microphysical properties against in-situ data from multi-aircraft observations, and studied the extent to which these retrieved properties are sufficiently constrained and consistent to reliably quantify the influence of aerosol loading on cloud droplet sizes. After constraining the spatial-temporal coincidence between satellite retrievals and in-situ measurements, we selected 17 non-drizzle comparison pairs. For these cases the mean aircraft profiling times were within one hour of Terra overpasses at both projected and un-projected (actual) aircraft positions for two different averaging domains of 5 km and 25 km. Retrieved quantities that were averaged over a larger domain of 25 km compared better statistically with in-situ observations than averages over a smaller domain of 5 km. Comparison at projected aircraft positions was slightly better than un-projected aircraft positions for some parameters. Overall, both MODIS-retrieved effective radius and LWP were larger but highly correlated with the in-situ measured effective radius and LWP, e.g., for averaging domains of 5 km, the biases are up to 1.75 μm and 0.02 mm whilst the correlation coefficients are about 0.87 and 0.85, respectively. The observed effective radius difference between the two decreased with increasing cloud drop number concentration (CDNC), and increased with increasing cloud geometrical thickness. Compared to the absolute effective radius difference, the correlations between the relative effective radius difference and CDNC or cloud geometric thickness are weaker. For averaging domains of 5 km and 25 km, the correlation coefficients between MODIS-retrieved and in-situ measured CDNC are 0.91 and 0.93 with fitting slopes of 1.23 and 1.27, respectively. If the cloud adiabaticity is taken into account, better agreements are achieved for both averaging domains (the fitting slopes are 1.04 and 1.07, respectively). Our comparison and sensitivity analysis of simulated retrievals demonstrate that both cloud geometrical thickness and cloud adiabaticity are important factors in satellite retrievals of effective radius and cloud drop number concentration. The large variabilities in cloud geometrical thickness and adiabaticity, the dependencies of cloud microphysical properties on both quantities (as demonstrated in our sensitivity study of simulated retrievals), and the inability to accurately account for either of them in retrievals lead to some uncertainties and biases in satellite retrieved cloud effective radius, cloud liquid water path, and cloud drop number concentration. However, strong correlations between satellite retrievals and in-situ measurements suggest that satellite retrievals of cloud effective radius, cloud liquid water path, and cloud drop number concentration can be used to investigate aerosol indirect effects qualitatively. © 2012 Author(s)."
"7201826462;7005981420;","Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS 3. Cloud overlap",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785911&partnerID=40&md5=59cb35ca0b059d5743bb3be0fa7238c7","The vertical distribution of cloud layers has a significant effect on atmospheric radiative heating/cooling distributions. While multiple cloud layers are often observed to occur simultaneously by surface observers, satellite cloud retrieval methodology typically assumes that any individual imager pixel contains a single cloud layer. The purpose of this paper is to demonstrate a bispectral method that detects imager pixels containing possible cloud overlap when an optically thin cirrus cloud overlies a low-level water cloud, with at least a 2-km separation between layers. The method is developed from a scatterplot of the near-infrared 1.63-μm band reflectances and the 11-μm brightness temperatures using data from the MODIS (Moderate-Resolution Imaging Spectroradiometer) airborne simulator (MAS). The bispectral method is applied to a scene recorded by the MAS scanning spectrometer that was flown on the NASA ER-2 during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) field campaign during April and May 1996. For a scene recorded on April 21, 1996, at 2000 UTC, the complex vertical cloud structure was captured by lidar backscatter measurements from the Cloud Lidar System (CLS). The bispectral method appears to have a promising facility for identifying areas containing potential cloud overlap."
"57214621667;7005297959;6506847650;7003436552;","The behaviour of ozone and peroxyacetyl nitrate concentrations for different wind regimes during the MEDCAPHOT-TRACE campaign in the greater area of Athens, Greece",1998,"10.1016/S1352-2310(97)00421-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032101725&doi=10.1016%2fS1352-2310%2897%2900421-4&partnerID=40&md5=9baa3f4b4512054a357718e26c9e9753","As a part of an international experimental field campaign, the association of air pollution with sea breeze circulation in the Greater Athens Area (GAA) is discussed on the basis of the behaviour of ozone and peroxyacetyl nitrate (PAN). During typical sea breeze days inside the Athens basin the ozone levels reach values up to 66% greater than values outside the basin. There is also an increase in ozone and PAN mixing ratios from the south to the north and from lower to higher locations, within the GAA. On-line PAN-measurements with a time resolution of 5 min at three sites located almost along a straight line across the Athens basin ranging from the island of Aegina in the Gulf of Saronikos to the northern border of the GAA show distinct peaks due to the pollution cloud NEPHOS."
"57206526682;7003627515;","The influence of clouds on the radiation budget of ice and snow surfaces in Antartica and Greenland in summer",1996,"10.1002/(sici)1097-0088(199611)16:11<1281::aid-joc83>3.3.co;2-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030419491&doi=10.1002%2f%28sici%291097-0088%28199611%2916%3a11%3c1281%3a%3aaid-joc83%3e3.3.co%3b2-1&partnerID=40&md5=4b0aee89eaea44a8038fd8df42bae498","Shortwave and longwave radiative surface fluxes over four different types of highly reflective surfaces are presented, with the emphasis on the dependence of these fluxes on total cloud coverage. Measurements were performed in summer during three field campaigns: one in Greenland and two in Antarctica. It was found that especially the strength of the dependence of the shortwave fluxes on cloud amount differed widely among the four locations; this is due to differences in surface albedo and cloud shortwave transmissivity. At two locations the net allwave radiation was found to increase with increasing cloud coverage (sometimes referred to as the 'radiation paradox'). It is demonstrated that this is due mainly to the fact that the shortwave cloud transmissivity at these sites is relatively high, which, in turn, is thought to be caused mainly by a low cloud optical thickness and by multiple scattering between surface and cloud-base. Whether or not the net surface radiation increases with increasing cloud coverage is found to depend chiefly on the values of the surface albedo and effective shortwave cloud transmissivity."
"7201706659;6701422868;6604000335;6603416853;56152167900;","A comparison of measured and modeled broadband fluxes from aircraft data during the ICE '89 field experiment",1992,"10.1175/1520-0426(1992)009<0391:ACOMAM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027061904&doi=10.1175%2f1520-0426%281992%29009%3c0391%3aACOMAM%3e2.0.CO%3b2&partnerID=40&md5=e192286ecc4232d0bb71982c9b081906","During the 1989 intensive field campaigns of the International Cirrus Experiment (ICE) over the North Sea, broadband radiative fluxes were measured in, above, and below cirrus cloud by a number of European meteorological research aircraft. One mission during the campaign was an intercomparison flight in clear air with no cloud above in order to compare, among other things, radiative flux measurements made by the U.K. C-130, the French Merlin, and the German Falcon aircraft. All three aircraft measured shortwave flux (0.3-3 μm) with standard Eppley pyranometers above and below the fuselage. The intercomparison showed agreement between the three aircraft of within 2% for both the upwelling and downwelling shortwave flux components. -from Authors"
"36054921000;7102567936;7005702722;","Cloud-resolving simulation of TOGA-COARE using parameterized large-scale dynamics",2013,"10.1002/jgrd.50510","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880872061&doi=10.1002%2fjgrd.50510&partnerID=40&md5=2e3ab90a963bc796385f40c60028ee0b","Variations in deep convective activity during the 4 month Tropical Ocean Global Atmosphere-Coupled Ocean Atmosphere Response Experiment (TOGA-COARE) field campaign are simulated using a cloud-resolving model (CRM). Convection in the model is coupled to large-scale vertical velocities that are parameterized using one of two different methods: the damped gravity wave (Damped-wave) method and the weak temperature gradient (WTG) method. The reference temperature profiles against which temperature anomalies are computed are taken either from observations or from a model integration with no large-scale vertical motion (but other forcings taken from observations); the parameterized large-scale vertical velocities are coupled to those temperature (or virtual temperature) anomalies. Sea surface temperature, radiative fluxes, and relaxation of the horizontal mean horizontal wind field are also imposed. Simulations with large-scale vertical velocity imposed from the observations are performed for reference. The primary finding is that the CRM with parameterized large-scale vertical motion can capture the intraseasonal variations in rainfall to some degree. Experiments in which one of several observation-derived forcings is set to its time-mean value suggest that those which influence direct forcings on the moist static energy budget - surface wind speed and sea surface temperature (which together influence surface evaporation) and radiative cooling - play the most important roles in controlling convection, particularly when the Damped-wave method is used. The parameterized large-scale vertical velocity has a vertical profile that is too bottom-heavy compared to observations when the Damped-wave method is used with vertically uniform Rayleigh damping on horizontal wind, but is too top-heavy when the WTG method is used. Key Points CRM with parameterized large-scale W captures part of intraseasonal variations Both surface turbulent fluxes and radiative cooling control convection Parameterized W is too top-heavy with WTG and too bottom-heavy with Damped-wave © 2013. American Geophysical Union. All Rights Reserved."
"36615106300;35551742400;","Sensitivity of mesoscale model urban boundary layer meteorology to the scale of urban representation",2011,"10.5194/acp-11-2951-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79953201197&doi=10.5194%2facp-11-2951-2011&partnerID=40&md5=6de552e0b5b3459f879c46039f06eafb","Mesoscale modeling of the urban boundary layer requires careful parameterization of the surface due to its heterogeneous morphology. Model estimated meteorological quantities, including the surface energy budget and canopy layer variables, will respond accordingly to the scale of representation. This study examines the sensitivity of the surface energy balance, canopy layer and boundary layer meteorology to the scale of urban surface representation in a real urban area (Detroit-Windsor (USA-Canada)) during several dry, cloud-free summer periods. The model used is the Weather Research and Forecasting (WRF) model with its coupled single-layer urban canopy model. Some model verification is presented using measurements from the Border Air Quality and Meteorology Study (BAQS-Met) 2007 field campaign and additional sources. Case studies span from ""neighborhood"" (10 s ∼308 m) to very coarse (120 s ∼3.7 km) resolution. Small changes in scale can affect the classification of the surface, affecting both the local and grid-average meteorology. Results indicate high sensitivity in turbulent latent heat flux from the natural surface and sensible heat flux from the urban canopy. Small scale change is also shown to delay timing of a lake-breeze front passage and can affect the timing of local transition in static stability. © 2011 Author(s)."
"11839267100;7202772927;55745955800;7006957668;7401936984;7401701196;55718206700;7006423931;57201725986;35467186900;","An indirect effect of ice nuclei on atmospheric radiation",2009,"10.1175/2008JAS2778.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65549138942&doi=10.1175%2f2008JAS2778.1&partnerID=40&md5=79931f7a412e20faddb2151a65614943","A three-dimensional cloud-resolving model (CRM) with observed large-scale forcing is used to study how ice nuclei (IN) affect the net radiative flux at the top of the atmosphere (TOA). In all the numerical experiments carried out, the cloud ice content in the upper troposphere increases with IN number concentration via the Bergeron process. As a result, the upward solar flux at the TOA increases whereas the infrared one decreases. Because of the opposite response of the two fluxes to IN concentration, the sensitivity of the net radiative flux at the TOA to IN concentration varies from one case to another. Six tropical and three midlatitudinal field campaigns provide data to model the effect of IN on radiation in different latitudes. Classifying the CRM simulations into tropical and midlatitudinal and then comparing the two types reveals that the indirect effect of IN on radiation is greater in the middle latitudes than in the tropics. Furthermore, comparisons between model results and observations suggest that observational IN data are necessary to evaluate long-term CRM simulations. © 2009 American Meteorological Society."
"7405367162;7202772927;7006957668;57211301037;6701681018;7401559815;7201844203;55109904700;6701669739;","Use of high-resolution satellite observations to evaluate cloud and precipitation statistics from cloud-resolving model simulations. Part I: South China Sea Monsoon experiment",2007,"10.1175/2007JAS2281.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-38349162368&doi=10.1175%2f2007JAS2281.1&partnerID=40&md5=b9c0e1fa1a4a1a150393be289a68f21c","Cloud and precipitation simulated using the three-dimensional (313) Goddard Cumulus Ensemble (GCE) model are compared to Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TM1) and Precipitation Radar (PR) rainfall measurements and Clouds and the Earth's Radiant Energy System (CERES) single scanner footprint (SSF) radiation and cloud retrievals. Both the model simulation and retrieved parameters are based upon observations made during the South China Sea Monsoon Experiment (SCSMEX) field campaign. The model-simulated cloud and rain systems are evaluated by systematically examining important parameters such as the surface rain rate, convective/stratiform percentage, rain profiles, cloud properties, and precipitation efficiency. It is demonstrated that the GCE model is capable of simulating major convective system development and reproduces the total surface rainfall amount as compared to rainfall estimated from the SCSMEX sounding network. The model yields a slightly higher total convective rain/ stratiform rain ratio than the TMI and PR observations. The GCE rainfall spectrum exhibits a greater contribution from heavy rains than those estimated from PR or TMI observations. In addition, the GCE simulation produces much greater amounts of snow and graupel than the TRMM retrievals. The model's precipitation efficiency of convective rain is close to the observations, but the precipitation efficiency of stratiform rain is much lower than the observations because of large amounts of slowly failing simulated snow and graupel. Compared to observations, the GCE produces more compact areas of intense convection and less anvil cloud, which are consistent with a smaller total cloud fraction and larger domain-averaged outgoing longwave radiation. © 2007 American Meteorological Society."
"6602252422;7201826462;7005729142;7403931916;6602550636;6603685334;7407116104;","The development of midlatitude cirrus models for MODIS using FIRE-I, FIRE-II, and ARM in situ data",2002,"10.1175/1520-0450(2002)041<0197:TDOMCM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036321092&doi=10.1175%2f1520-0450%282002%29041%3c0197%3aTDOMCM%3e2.0.CO%3b2&partnerID=40&md5=c3741720fc9badd32bdbd880f152ed96","Detailed in situ data from cirrus clouds have been collected during dedicated field campaigns, but the use of the size and habit distribution data has been lagging in the development of more realistic cirrus scattering models. In this study, the authors examine the use of in situ cirrus data collected during three field campaigns to develop more realistic midlatitude cirrus microphysical models. Data are used from the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE)-I (1986) and FIRE-II (1991) campaigns and from a recent Atmospheric Radiation Measurement (ARM) Program campaign held in March-April of 2000. The microphysical models are based on measured vertical distributions of both particle size and particle habit and are used to develop new scattering models for a suite of moderate-resolution imaging spectoradiometer (MODIS) bands spanning visible, near-infrared, and infrared wavelengths. The sensitivity of the resulting scattering properties to the underlying assumptions of the assumed particle size and habit distributions are examined. It is found that the near-infrared bands are sensitive not only to the discretization of the size distribution but also to the assumed habit distribution. In addition, the results indicate that the effective diameter calculated from a given size distribution tends to be sensitive to the number of size bins that are used to discretize the data and also to the ice-crystal habit distribution."
"56722821200;7401793588;57203386948;57208765879;6506730508;55805773500;6603081424;","Shortwave direct radiative effects of above-cloud aerosols over global oceans derived from 8 years of CALIOP and MODIS observations",2016,"10.5194/acp-16-2877-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960387809&doi=10.5194%2facp-16-2877-2016&partnerID=40&md5=7327b7f719be49b7a8fd1dd9af132cc4","In this paper, we studied the frequency of occurrence and shortwave direct radiative effects (DREs) of abovecloud aerosols (ACAs) over global oceans using 8 years (2007-2014) of collocated CALIOP and MODIS observations. Similar to previous work, we found high ACA occurrence in four regions: southeastern (SE) Atlantic region, where ACAs are mostly light-absorbing aerosols, i.e., smoke and polluted dust according to CALIOP classification, originating from biomass burning over the African Savanna; tropical northeastern (TNE) Atlantic and the Arabian Sea, where ACAs are predominantly windblown dust from the Sahara and Arabian deserts, respectively; and the northwestern (NW) Pacific, where ACAs are mostly transported smoke and polluted dusts from Asian. From radiative transfer simulations based on CALIOP-MODIS observations and a set of the preselected aerosol optical models, we found the DREs of ACAs at the top of atmosphere (TOA) to be positive (i.e., warming) in the SE Atlantic and NW Pacific regions, but negative (i.e., cooling) in the TNE Atlantic Ocean and the Arabian Sea. The cancellation of positive and negative regional DREs results in a global ocean annual mean diurnally averaged cloudy-sky DRE of 0.015Wm-2 (range of -0.03 to 0.06Wm-2/ at TOA. The DREs at surface and within the atmosphere are -0.15Wm-2 (range of -0.09 to -0.21Wm-2/, and 0.17Wm-2 (range of 0.11 to 0.24Wm-2/, respectively. The regional and seasonal mean DREs are much stronger. For example, in the SE Atlantic region, the JJA (July-August) seasonal mean cloudy-sky DRE is about 0.7Wm-2 (range of 0.2 to 1.2Wm-2/ at TOA. All our DRE computations are publicly available1. The uncertainty in our DRE computations is mainly caused by the uncertainties in the aerosol optical properties, in particular aerosol absorption, the uncertainties in the CALIOP operational aerosol optical thickness retrieval, and the ignorance of cloud and potential aerosol diurnal cycle. In situ and remotely sensed measurements of ACA from future field campaigns and satellite missions and improved lidar retrieval algorithm, in particular vertical feature masking, would help reduce the uncertainty. © 2016 Author(s)."
"7004242319;57217559271;21739304600;56521673500;6701546267;","The characterization of ice hydrometeor gamma size distributions as volumes in N0-λ-μ phase space: Implications for microphysical process modeling",2015,"10.1175/JAS-D-14-0011.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923069585&doi=10.1175%2fJAS-D-14-0011.1&partnerID=40&md5=b889faebeb260511caf39c569330cde5","Gamma distributions represent particle size distributions (SDs) in mesoscale and cloud-resolving models that predict one, two, or three moments of hydrometeor species. They are characterized by intercept (N0), slope (λ), and shape (μ) parameters prognosed by such schemes or diagnosed based on fits to SDs measured in situ in clouds. Here, ice crystal SDs acquired in arctic cirrus during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) and in hurricanes during the National Aeronautic and Space Administration (NASA) African Monsoon Multidisciplinary Analyses (NAMMA) are fit to gamma distributions using multiple algorithms. It is shown that N0, λ, and μ are not independent parameters but rather exhibit mutual dependence. Although N0, λ, and μ are not highly dependent on choice of fitting routine, they are sensitive to the tolerance permitted by fitting algorithms, meaning a three-dimensional volume in N0-λ-μ phase space is required to represent a single SD. Depending on the uncertainty in the measured SD and on how well a gamma distribution matches the SD, parameters within this volume of equally realizable solutions can vary substantially, with N0, in particular, spanning several orders of magnitude. A method to characterize a family of SDs as an ellipsoid in N0-λ-μ phase space is described, with the associated scatter in N0-λ-μ for such families comparable to scatter in N0, λ and μ observed in prior field campaigns conducted in different conditions. Ramifications for the development of cloud parameterization schemes and associated calculations of microphysical process rates are discussed. © 2015 American Meteorological Society."
"57217869945;30967521200;6507139751;57219832587;16481745400;","Using the WIBS-4 (Waveband Integrated Bioaerosol Sensor) technique for the on-line detection of pollen grains",2014,"10.1080/02786826.2013.872768","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896893645&doi=10.1080%2f02786826.2013.872768&partnerID=40&md5=13a93062b9f174320127098577de36da","Primary biological aerosol particles (PBAP) such as pollen and fungal spores can induce allergenic responses and affect health in general. Conditions such as allergic rhinitis (hay fever) and asthma have been related to pollen concentrations. Likewise some pollen have been shown to induce ice nucleation and cloud condensation at higher temperatures than those associated with some chemical species, thereby affecting planet Earth's albedo and overall radiative balance. Hence, the near real-time (on-line) monitoring of airborne pollen and other PBAP using a variety of spectroscopic and light scattering techniques represents an area of growing development and consequence. In this study, two separate field campaigns (one at a rural site in Ireland and the other at an urbanized location in Germany) were performed to detect and quantify pollen releases using a novel on-line fluorescence spectrometer (WIBS-4). The results were compared with results obtained using more traditional Hirst-type impactors. Size, ""shape,"" and fluorescence characteristics of ambient particles were used to determine the concentrations and identity of the PBAP likely to be pollen grains. The concentration results obtained for both methodologies at both the Irish and German sites correlated very well, with R 2 values &gt;0.9 determined for both campaigns. Furthermore, the sizing data available from the WIBS-4 approach employed in Ireland indicated that pollen grains can be identified in appropriate conditions. WIBS-4 measurements of Yew pollen both in the laboratory and at the rural site indicated almost identical size ranges of 25 to 27 μm. Yew pollen is generally reported to be in this range, but the measurements reported here are the first of their type providing data on the size of in-flight Yew pollen. © 2014 Copyright Taylor and Francis Group, LLC."
"7103016965;7005729142;7801353107;7004715270;26434854300;7402049334;7003406689;7005773698;","Ice in clouds experiment-layer clouds. Part II: Testing characteristics of heterogeneous ice formation in lee wave clouds",2012,"10.1175/JAS-D-11-026.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858266345&doi=10.1175%2fJAS-D-11-026.1&partnerID=40&md5=99ddf24538a64fb22efa0a4191c827f8","Heterogeneous ice nucleation is a source of uncertainty in models that represent ice clouds. The primary goal of the Ice in Clouds Experiment-Layer Clouds (ICE-L) field campaign was to determine if a link can be demonstrated between ice concentrations and the physical and chemical characteristics of the ambient aerosol. This study combines a 1D kinematic framework with lee wave cloud observations to infer ice nuclei (IN) concentrations that were compared to IN observations from the same flights. About 30 cloud penetrations from six flights were modeled. The temperature range of the observations was -16° to -32°C. Of the three simplified ice nucleation representations tested (deposition, evaporation freezing, and condensation/ immersion droplet freezing), condensation/immersion freezing reproduced the lee wave cloud observations best. IN concentrations derived from the modeling ranged from 0.1 to 13 L -1 compared to 0.4 to 6 L -1 from an IN counter. A better correlation was found between temperature and the ratio of IN concentration to the concentration of large aerosol (&gt;500 nm) than between IN concentration and the large aerosol concentration or temperature alone. © 2012 American Meteorological Society."
"57197636789;7003606341;57193882808;","A numerical investigation of entrainment and transport within a stratocumulus-topped boundary layer",2009,"10.1002/qj.354","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649440722&doi=10.1002%2fqj.354&partnerID=40&md5=d02c54f6bdd77f70b7daed1f362e8902","Entrainment into the stratocumulus-topped boundary layer (STBL) is investigated by means of large-eddy simulations. Set-up of the numerical experiment is based on the research flight RF-01 in the DYCOMS-II field campaign. We focus on the stability of the flow in the cloud-top region known as the Entrainment Interface Layer (EIL). We calculate the local gradient Richardson number, Ri, at the surface of maximum static stability and at the material top of the STBL defined by a threshold of the total water content. We found that regions in which updraughts impinge upon the inversion and diverge horizontally are characterized by small values of Ri. Resulting turbulence is responsible for entrainment and formation of the EIL. Volumes of the STBL air and the free-tropospheric air from above it, mixed in proportion resulting in negative buoyancy and typically void of cloud water, form 'cloud holes' - trenches of descending cloud-free air which surround updraught areas. The entrainment process is further analyzed using a passive scalar introduced after three hours of the simulation above the layer of maximum static stability. The mixing fraction of this scalar in the air within the cloud holes falls within the range corresponding to the buoyancy reversal. Some of the negatively buoyant mixtures sinking through the cloud holes are wrapped around the edge of cloudy regions and recirculated into the cloud, which causes a local increase of the cloud-base height. The rest of the entrained free-tropospheric air sinks slowly into the STBL and leads to its gradual dilution. Copyright © 2008 Royal Meteorological Society."
"12803465300;7403931916;7201826462;7005729142;7004853382;55621952600;6603697954;7003696273;","Scattering database in the millimeter and submillimeter wave range of 100-1000 GHz for nonspherical ice particles",2009,"10.1029/2008JD010451","https://www.scopus.com/inward/record.uri?eid=2-s2.0-66449105831&doi=10.1029%2f2008JD010451&partnerID=40&md5=ea2800d29c71927351a4afb2f6596ff8","The inference of ice cloud properties from spaceborne sensors is sensitive to the retrieval algorithms and satellite sensors used. To approach a better understanding of ice cloud properties, it is necessary to combine satellite measurements from multiple platforms and sensors operating in visible, infrared, and millimeter and submillimeterwave regions of the electromagnetic spectrum. The single-scattering properties of ice particles with consistent ice particle models are the basis for estimating the optical and microphysical properties of ice clouds from multiple satellite sensors. In this study, the single-scattering properties (extinction efficiency, absorption efficiency, single-scattering albedo, asymmetry factor, and scattering phase matrix) of nonspherical ice particles, assumed to be hexagonal solid and hollow columns, hexagonal plates, 3D bullet rosettes, aggregates, and droxtals, are computed from the discrete dipole approximation method for 21 millimeter and submillimeter-wave frequencies ranging from 100 to 1000 GHz. A database of the single-scattering properties of nonspherical ice particles are developed for 38 particle sizes ranging from 2 to 2000m in terms of particle maximum dimension. The bulk scattering properties of ice clouds consisting of various ice particles, which are the fundamental to the radiative transfer in ice clouds, are developed on the basis of a set of 1119 particle size distributions obtained from various field campaigns. Copyright 2009 by the American Geophysical Union."
"8273707700;6507990247;7005461477;","Radar and lightning observations of the 3 June 2000 electrically inverted storm from STEPS",2007,"10.1175/2006MWR1953.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36748998845&doi=10.1175%2f2006MWR1953.1&partnerID=40&md5=7d9c3ef25a5fa84c2b391a78a5b2bd7d","This study addresses the kinematic, microphysical, and electrical evolution of an isolated convective storm observed on 3 June 2000 during the Severe Thunderstorm Electrification and Precipitation Study field campaign. Doppler-derived vertical velocities, radar reflectivity, hydrometeor classifications from polarimetric radar, and Lightning Mapping Array (LMA) charge structures are examined over a nearly 3-h period. This storm, characterized as a low-precipitation supercell, produced modest amounts of hail, determined by fuzzy-logic hydrometeor classification as mostly small (&lt;2 cm) hail, with one surface report of large (≥2 cm) hail. Doppler-derived updraft speeds peaked between 20 and 25 m s-1, and reflectivity was never greater than 60 dBZ. The most striking feature of this storm was its total lack of cloud-to-ground (CG) lightning. Though this storm was electrically active, with maximum flash rates near 30 per minute, no CG flashes of either polarity were detected. The charge structure inferred from the LMA observations was consistent with an inverted dipole, defined as having a midlevel positive charge region below upper-level negative charge. Inverted charge structures have typically been considered conducive to producing positive CG lightning; however, the 3 June storm appeared to lack the lower negative charge layer below the inverted dipole that is thought to provide the downward electrical bias necessary for positive CG lightning. © 2007 American Meteorological Society."
"7006306835;7202252296;","Organic aerosol effects on fog droplet spectra",2004,"10.1029/2003JD004427","https://www.scopus.com/inward/record.uri?eid=2-s2.0-4143137504&doi=10.1029%2f2003JD004427&partnerID=40&md5=895653bfc0b535294307c3167dd493e0","Organic aerosol alters cloud and fog properties through surface tension and solubility effects. This study characterizes the role of organic compunds in affecting fog droplet number concentration by initializing and comparing detailed particle microphysical simulations with two field campaigns in the Po Valley. The size distribution and chemical composition of aerosol were based on the measurements made in the Po Valley Fog Experiments in 1989 and 1998-1999. Two types of aerosol with different hygroscopicity were considered: the less hygroscopic particles, composed mainly of organic compounds, and the more hygroscopic particles, composed mainly of inorganic salts. The organic fraction of aerosol mass explicitly modeled as a mixture of seven soluble compounds [Fuzzi et al., 2001] by employing a functional group-based thermodynamic model [Ming and Russell, 2002}. Condensable gases in the vapor phase included nitric acid, sulfuric acid, and ammonia. The maximum supersaturation in the simulation is 0.030% and is comparable to the calculation by Noone et al. [2002] inferred from measured residual particle fractions. The minimum activation diameters of the less and more hygroscopic particles are 0.49 μm and 0.40 μm, respectively. The predicted residual particle fractions are in agreement with measurements. The organic components of aerosol account for 34% of the droplet residual particle mass and change the average droplet number concentration by -10-6%, depending on the lowering o droplet surface tension and the interactions among dissolving ions. The hygroscopic growth of particles due to the presence of water-soluble organic compounds enhances the condensation of nitric acid and ammonia due to the increased surface area, resulting in a 9% increase in the average droplet number concentration. Assuming ideal behavior of aqueous solutions of water-soluble organic compounds overestimates the hygroscopic growth of particles and increases droplet numbers by 6%. The results are sensitive to microphysical processes such as condensation of soluble gases, which increases the average droplet number concentration by 26%. Wet deposition plays an important role in controlling liquid water content in this shallow fog. Copyright 2004 by the Geophysical Union."
"7801360013;57191236241;6603669676;","Seasonal variation of tropical forest LAI based on field measurements in Central African Republic",2003,"10.1016/S0168-1923(03)00138-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0345393224&doi=10.1016%2fS0168-1923%2803%2900138-2&partnerID=40&md5=0061431fe29f75108164340fcf2cf1e8","The research presented in this paper focuses on the measurement over a large area of seasonal variation in foliage of a tropical forest. This effort is part of a larger experiment linking ground and space observations over time. A dedicated 8-month field campaign was carried out in Ngotto, a semi-deciduous forest in the Central African Republic to study the spatial and temporal variability of Leaf Area Index (LAI). First, the sensitivity of the LAI-2000 Plant Canopy Analyser instrument was tested. Five sensitivity variables were tested in all: measurement procedure, positioning error, Solar Zenith Angle (SZA) effects, foliage changes, and cloud cover variations. Secondly, the LAI spatial variability was assessed based on geostatistical analysis of measured transects with lags ranging from 30 cm to 10 m. The variogram analysis, showed an overall variance estimate of 0.47 (sill) and a loss of spatial correlation at a distance of 30 m (range). These values were used to calculate the sample size and the minimum distance between adjacent positions, respectively, in order to design a relevant sampling scheme for assessing forest foliage seasonality. Throughout the 8-month field campaign, the LAI was measured at least monthly at 64 positions within 4 km2 forest sites. A seasonal change of LAI of 0.34 was measured for this tropical forest and found to be in sync with the dry season which lasts three months. © 2003 Elsevier B.V. All rights reserved."
"57203958412;7801511693;55891393200;24438293600;","Using UAS optical imagery and SfM photogrammetry to characterize the surface grain size of gravel bars in a braided river (Vénéon River, French Alps)",2017,"10.1016/j.geomorph.2017.01.039","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013658028&doi=10.1016%2fj.geomorph.2017.01.039&partnerID=40&md5=c0a84ea8fe3aaaa8771dab46e4fa91cf","This paper explores the potential of unmanned aerial system (UAS) optical aerial imagery to characterize grain roughness and size distribution in a braided, gravel-bed river (Vénéon River, French Alps). With this aim in view, a Wolman field campaign (19 samples) and five UAS surveys were conducted over the Vénéon braided channel during summer 2015. The UAS consisted of a small quadcopter carrying a GoPro camera. Structure-from-Motion (SfM) photogrammetry was used to extract dense and accurate three-dimensional point clouds. Roughness descriptors (roughness heights, standard deviation of elevation) were computed from the SfM point clouds and were correlated with the median grain size of the Wolman samples. A strong relationship was found between UAS-SfM-derived grain roughness and Wolman grain size. The procedure employed has potential for the rapid and continuous characterization of grain size distribution in exposed bars of gravel-bed rivers. The workflow described in this paper has been successfully used to produce spatially continuous grain size information on exposed gravel bars and to explore textural changes following flow events. © 2017 Elsevier B.V."
"55175095300;7006145109;6603400565;55576515800;","Multi-temporal, multi-sensor retrieval of terrestrial vegetation properties from spectral-directional radiometric data",2015,"10.1016/j.rse.2014.10.030","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949115322&doi=10.1016%2fj.rse.2014.10.030&partnerID=40&md5=d0cd05ac2eb3e6d7f74e25fc1e5c6b90","The synergy of a time series of optical satellite observations from a variety of sensors can be exploited to improve the retrieval of biophysical variables. Information from different sensors may assist in the variable retrieval by limiting potential ambiguities. This involves observations at different spatial, spectral, temporal and angular resolutions, etc. Furthermore, using timely data is of much importance for vegetation monitoring in environmental modeling. While the other necessary variables for such models can be collected daily (e.g. meteorological variables), the temporal resolution of optical sensors (high to intermediate spatial resolutions) does not allow having temporally frequent products of vegetation characteristics due to the revisit time of the sensors and cloud coverage. A multi-temporal, multi-sensor approach applied to a temporal sequence of radiometric data acquired by different sensors can improve mapping and monitoring of vegetation state variables over time. Even when no observations are available due to cloudiness or orbital configuration, the prior retrievals are taken.The study provides a prototype proof of concept for a multi-temporal, multi-sensor approach to retrieve vegetation state variables using data collected by different imaging spectral-radiometers over time. Focus is given to the retrieval of LAI, fCover and chlorophyll content over the agricultural test site in Barrax, Spain. The approach is evaluated over a limited number of remotely sensed data acquired during a short period in the Sentinel-3 Experiment (SEN3EXP 2009) field campaign. A variety of satellite observations including CHRIS-Proba, Landsat TM and ASTER are integrated and combined by means of the multi-temporal, multi-sensor approach and through inversion of a coupled surface-atmosphere radiative transfer model. We applied the iterative Bayesian model inversion in which retrievals of the current observation are incorporated as prior information to the successor observation.This paper presents an overview of the results and challenges in utilizing the multi-temporal, multi-sensor approach and the Bayesian inversion technique in the retrieval of terrestrial vegetation properties. Overall, the accuracy obtained with data acquired by multiple sensors over time was higher than when using a single sensor. LAI and fCover were retrieved with RMSE= 0.7 (m2/m2) and 0.1 respectively (multiple sensors), while RMSE= 1.09 (m2/m2) and 0.15 respectively, when using data acquired by a single sensor. © 2014 Elsevier Inc."
"35749688400;7005135473;","Satellite and surface-based remote sensing of Southeast Asian aerosols and their radiative effects",2013,"10.1016/j.atmosres.2012.02.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84873276073&doi=10.1016%2fj.atmosres.2012.02.018&partnerID=40&md5=25af007ec760dd1937741c4bfc0c650f","Using one year (December 2006-November 2007) of the Moderate Resolution Imaging SpectroRadiometer (MODIS), Multi-Angle Imaging SpectroRadiometer (MISR), and Clouds and the Earth's Radiant Energy System (CERES) data sets from NASA's Terra satellite, we assess the spatial and temporal distributions of aerosol properties (Aerosol Optical Depth, Fine Mode Fraction, and Single Scattering albedo) in the Southeast Asian region (SEA, 10°S-25°N, 90°E-150°E). We also provide a quantitative evaluation of regional cloud-free diurnally averaged shortwave aerosol radiative effects (SWARE) at the top of atmosphere (TOA) over both land and ocean. Our results indicate that the diurnally averaged shortwave radiative effects at the TOA over land and ocean are (-6.4±1.2Wm-2) and (-5.9±1.3Wm-2) with corresponding 550nm aerosol optical depths of 0.27±0.24 and 0.12±0.10. Fine aerosol particles (&lt;0.6μm) dominate the continental areas during the whole study period, which represents large fractions of biomass burning aerosols and anthropogenic pollutant aerosols. Our results also indicate that the monthly averaged cloud cover fractions over this region are above 60%. Therefore, further sampling of aerosols underneath these cloud layers is needed in future field campaigns. © 2012 Elsevier B.V."
"7201798916;57206332144;7004174939;7102084129;35464731600;6506257601;35887706900;7103011104;7005880268;7004864963;","Remote sensing the vertical profile of cloud droplet effective radius, thermodynamic phase, and temperature",2011,"10.5194/acp-11-9485-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052872030&doi=10.5194%2facp-11-9485-2011&partnerID=40&md5=9b21379a82fc9d2da7a471bf6b38968e","Cloud-aerosol interaction is a key issue in the climate system, affecting the water cycle, the weather, and the total energy balance including the spatial and temporal distribution of latent heat release. Information on the vertical distribution of cloud droplet microphysics and thermodynamic phase as a function of temperature or height, can be correlated with details of the aerosol field to provide insight on how these particles are affecting cloud properties and their consequences to cloud lifetime, precipitation, water cycle, and general energy balance. Unfortunately, today's experimental methods still lack the observational tools that can characterize the true evolution of the cloud microphysical, spatial and temporal structure in the cloud droplet scale, and then link these characteristics to environmental factors and properties of the cloud condensation nuclei. Here we propose and demonstrate a new experimental approach (the cloud scanner instrument) that provides the microphysical information missed in current experiments and remote sensing options. Cloud scanner measurements can be performed from aircraft, ground, or satellite by scanning the side of the clouds from the base to the top, providing us with the unique opportunity of obtaining snapshots of the cloud droplet microphysical and thermodynamic states as a function of height and brightness temperature in clouds at several development stages. The brightness temperature profile of the cloud side can be directly associated with the thermodynamic phase of the droplets to provide information on the glaciation temperature as a function of different ambient conditions, aerosol concentration, and type. An aircraft prototype of the cloud scanner was built and flew in a field campaign in Brazil. The CLAIM-3D (3-Dimensional Cloud Aerosol Interaction Mission) satellite concept proposed here combines several techniques to simultaneously measure the vertical profile of cloud microphysics, thermodynamic phase, brightness temperature, and aerosol amount and type in the neighborhood of the clouds. The wide wavelength range, and the use of multi-angle polarization measurements proposed for this mission allow us to estimate the availability and characteristics of aerosol particles acting as cloud condensation nuclei, and their effects on the cloud microphysical structure. These results can provide unprecedented details on the response of cloud droplet microphysics to natural and anthropogenic aerosols in the size scale where the interaction really happens. © 2011 Author(s)."
"7202057166;7005729142;","The size distribution and mass-weighted terminal velocity of low-latitude tropopause cirrus crystal populations",2009,"10.1175/2009JAS3004.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-69949151327&doi=10.1175%2f2009JAS3004.1&partnerID=40&md5=bb5c41d6a75b79fa1b886df13c024cd6","Ice crystal terminal velocities govern the lifetime of radiatively complex, climatologically important, low-latitude tropopause cirrus clouds. To better understand cloud lifetimes, the terminal velocities of low-latitude tropopause cirrus cloud particles have been estimated using data from aircraft field campaigns. Data used in this study were collected during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) and the Pre-Aura Validation Experiment (Pre-AVE). Particle properties were measured with the NCAR video ice particle sampler (VIPS) probe, thus providing information about particles in a poorly understood size range. Data used in this study were limited to high-altitude nonconvective thin clouds with temperatures between -56° and -86°C. Realistic particle terminal velocity estimates require accurate values of particle projected area and mass. Exponential functions were used to predict the dimensional properties of ice particles smaller than 200 microns and were found to predict ice water content measurements well when compared to power-law representations. The shapes of the particle size distributions were found to be monomodal and were well represented by exponential or gamma functions. Incorporating these findings into terminal velocity calculations led to lower values of mass-weighted terminal velocities for particle populations than are currently predicted for low-latitude ice clouds. New parameterizations for individual particle properties as well as particle size distribution properties are presented and compared to commonly used parameterizations. Results from this study are appropriate for use in estimating the properties of low-latitude thin and subvisible cirrus at temperatures lower than -56°C. © 2009 American Meteorological Society."
"8900058400;57204252724;7003480967;9332706900;13610168000;","Seasonal and diurnal trends in black carbon properties and co-pollutants in Mexico City",2015,"10.5194/acp-15-9693-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940661645&doi=10.5194%2facp-15-9693-2015&partnerID=40&md5=74601f13adb5f6c6f01d4a209cb866e9","The Mexico City metropolitan area (MCMA) is a region that continues to grow in population and vehicular traffic as well as being the largest source of short-lived climate pollutants (SLCP) in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e., ozone (O3) and carbon monoxide (CO), but particulate matter (PM2.5 and PM10) and black carbon (BC) have shown a less positive response to mitigation strategies that have been in place for almost 3 decades. For the first time, extended measurements of equivalent black carbon (eBC), derived from light absorption measurements, have been made using a Photoacoustic Extinctiometer (PAX) over a 13 month period from March 2013 through March 2014. The daily trends in workdays (Monday through Saturday) and Sunday eBC, PM2.5 and the co-pollutants CO, O3 and NOx are evaluated with respect to the three primary seasons in the MCMA: rainy, cold and dry and warm and dry. The maximum values in all of the particle and gas concentrations were significantly larger (Student's t test, P &lt; 0.05) during the dry periods than in the rainy season. The changes from rainy to dry seasons for eBC, PM2.5, CO, O3 and NOx were 8.8 to 13.1 μg m-3 (40 %), 49 to 73 μg m-3 (40 %), 2.5 to 3.8 ppm (40 %), 73 to 100 ppb (30 %) and 144 to 252 ppb (53 %), respectively. The primary factors that lead to these large changes between the wet and dry seasons are the accelerated vertical mixing of boundary layer and free tropospheric air by the formation of clouds that dilutes the concentration of the SLCPs, the decreased actinic flux that reduces the production of ozone by photochemical reactions and the heavy, almost daily rain that removes particulate matter. A significant ""weekend effect"" was also identified, particularly the decrease in BC due to fewer large transport vehicles that are fueled by diesel, which produces a large fraction of the BC. The other co-pollutant concentrations are also significantly less on weekends except for O3 that shows no change in maximum values from workdays to Sundays. This lack of change is a result of the balancing effects of lower precursor gases, i.e., VOCs, offset by lower concentrations of NOx, that is an O3 inhibitor. A comparison of the average maximum value of eBC measured during the 1 year period of the current study, with maximum values measured in shorter field campaigns in 2000 and 2006, shows no significant change in the eBC emissions over a 14 year period. This suggests that new methods may need to be developed that can decrease potentially toxic levels of this particulate pollutant. © Author(s) 2015."
"56242287700;39161655400;56798586300;20434917300;36465445700;57202066728;7003362098;8853393600;25521451000;","A better understanding of hydroxyl radical photochemical sources in cloud waters collected at the puy de Dôme station - Experimental versus modelled formation rates",2015,"10.5194/acp-15-9191-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84939824870&doi=10.5194%2facp-15-9191-2015&partnerID=40&md5=a827033414ae0dbd67d93f2f052f753d","The oxidative capacity of the cloud aqueous phase is investigated during three field campaigns from 2013 to 2014 at the top of the puy de Dôme station (PUY) in France. A total of 41 cloud samples are collected and the corresponding air masses are classified as highly marine, marine and continental. Hydroxyl radical (HO•) formation rates (RHO•f) are determined using a photochemical setup (xenon lamp that can reproduce the solar spectrum) and a chemical probe coupled with spectroscopic analysis that can trap all of the generated radicals for each sample. Using this method, the obtained values correspond to the total formation of HO• without its chemical sinks. These formation rates are correlated with the concentrations of the naturally occurring sources of HO•, including hydrogen peroxide, nitrite, nitrate and iron. The total hydroxyl radical formation rates are measured as ranging from approximately 2 × 10&amp;minus;11 to 4 × 10&amp;minus;10 M s-1, and the hydroxyl radical quantum yield formation (&amp;Phi;HO•) is estimated between 10&amp;minus;4 and 10-2. Experimental values are compared with modelled formation rates calculated by the model of multiphase cloud chemistry (M2C2), considering only the chemical sources of the hydroxyl radicals. The comparison between the experimental and the modelled results suggests that the photoreactivity of the iron species as a source of HO• is overestimated by the model, and H2O2 photolysis represents the most important source of this radical (between 70 and 99 %) for the cloud water sampled at the PUY station (primarily marine and continental). © Author(s) 2015."
"55481711800;16241933300;6507864329;6701611096;7005054220;6603343577;7101638253;","Higher surface ozone concentrations over the Chesapeake Bay than over the adjacent land: Observations and models from the DISCOVER-AQ and CBODAQ campaigns",2014,"10.1016/j.atmosenv.2013.11.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889648093&doi=10.1016%2fj.atmosenv.2013.11.008&partnerID=40&md5=8696fd1a136ff961597fc7ae3a2fc61f","Air quality models, such as the Community Multiscale Air Quality (CMAQ) model, indicate decidedly higher ozone near the surface of large interior water bodies, such as the Great Lakes and Chesapeake Bay. In order to test the validity of the model output, we performed surface measurements of ozone (O3) and total reactive nitrogen (NOy) on the 26-m Delaware II NOAA Small Research Vessel experimental (SRVx), deployed in the Chesapeake Bay for 10 daytime cruises in July 2011 as part of NASA's GEO-CAPE CBODAQ oceanographic field campaign in conjunction with NASA's DISCOVER-AQ air quality field campaign. During this 10-day period, the EPA O3 regulatory standard of 75ppbv averaged over an 8-hperiod was exceeded four times over water while ground stations in the area only exceeded the standard at most twice. This suggests that on days when the Baltimore/Washington region is in compliance with the EPA standard, air quality over the Chesapeake Bay might exceed the EPA standard. Ozone observations over the bay during the afternoon were consistently 10-20% higher than the closest upwind ground sites during the 10-day campaign; this pattern persisted during good and poor air quality days. A lower boundary layer, reduced cloud cover, slower dry deposition rates, and other lesser mechanisms, contribute to the local maximum of ozone over the Chesapeake Bay. Observations from this campaign were compared to a CMAQ simulation at 1.33km resolution. The model is able to predict the regional maximum of ozone over the Chesapeake Bay accurately, but NOy concentrations are significantly overestimated. Explanations for the overestimation of NOy in the model simulations are also explored. © 2013 Elsevier Ltd."
"12803465300;7403931916;7201826462;7005729142;7403282069;","Parameterization of shortwave and longwave radiative properties of ice clouds for use in climate models",2009,"10.1175/2009JCLI2844.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77649280122&doi=10.1175%2f2009JCLI2844.1&partnerID=40&md5=ee7787baa989edc24737d32c39d3a301","Climate modeling and prediction require that the parameterization of the radiative effects of ice clouds be as accurate as possible. The radiative properties of ice clouds are highly sensitive to the single-scattering properties of ice particles and ice cloud microphysical properties such as particle habits and size distributions. In this study, parameterizations for shortwave (SW) and longwave (LW) radiative properties of ice clouds are developed for three existing schemes using ice cloud microphysical properties obtained from five field campaigns and broadband-averaged single-scattering properties of nonspherical ice particles as functions of the effective particle size De (defined as 1.5 times the ratio of total volume to total projected area), which include hexagonal solid columns and hollow columns, hexagonal plates, six-branch bullet rosettes, aggregates, and droxtals. A combination of the discrete ordinates radiative transfer model and a line-by-line model is used to sim- ulate ice cloud radiative forcing (CRF) at both the surface and the top of the atmosphere (TOA) for the three redeveloped parameterization schemes. The differences in CRF for different parameterization schemes are in the range of -5 to 5 Wm-2. In general, the large differences in SW and total CRF occur for thick ice clouds, whereas the large differences in LW CRF occur for ice clouds with small ice particles (De less than 20 μm). The redeveloped parameterization schemes are then applied to the radiative transfer models used for climate models. The ice cloud optical and microphysical properties from the Moderate Resolution Imaging Spec- troradiometer (MODIS) cloud product over a granule and the collocated atmospheric profiles from the Atmospheric Infrared Sounder (AIRS) product are input into these radiative transfer models to compare the differences in CRF between the redeveloped and existing parameterization schemes. Although differences between these schemes are small in the LW CRF, the differences in the SW CRF are quite large. © 2009 American Meteorological Society."
"8670222900;36449278400;7006532784;8618282100;7006471143;","Quantifying the imprint of a severe hector thunderstorm during ACTIVE/SCOUT-O3 onto the water content in the upper troposphere/lower stratosphere",2009,"10.1175/2008MWR2666.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70350302279&doi=10.1175%2f2008MWR2666.1&partnerID=40&md5=31d4c1cf7b68eb650b5b73f1e9dd296c","The development of a severe Hector thunderstorm that formed over the Tiwi Islands, north of Australia, during the Aerosol and Chemical Transport in Tropical Convection/Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere (ACTIVE/ SCOUT-O3) field campaign in late 2005, is simulated by the Advanced Research Weather Research and Forecasting (ARW) model and the Met Office Unified Model (UM). The general aim of this paper is to investigate the role of isolated deep convection over the tropics in regulating the water content in the upper troposphere/lower stratosphere (UT/LS). Using a horizontal resolution as fine as 1 km, the numerical simulations reproduce the timing, structure, and strength of Hector fairly well when compared with field campaign observations. The sensitivity of results from ARW to horizontal resolution is investigated by running the model in a large-eddy simulation mode with a horizontal resolution of 250 m. While refining the horizontal resolution to 250 m leads to a better representation of convection with respect to rainfall, the characteristics of the Hector thunderstorm are basically similar in space and time to those obtained in the 1-km-horizontal-resolution simulations. Several overshooting updrafts penetrating the tropopause are produced in the simulations during the mature stage of Hector. The penetration of rising towering cumulus clouds into the LS maintains the entrainment of air at the interface between the UT and the LS. Vertical exchanges resulting from this entrainment process have a significant impact on the redistribution of atmospheric constituents within the UT/ LS region at the scale of the islands. In particular, a large amount of water is injected in the LS. The fate of the ice particles as Hector develops drives the water vapor mixing ratio to saturation by sublimation of the injected ice particles, moistening the air in the LS. The moistening was found to be fairly significant above 380 K and averaged about 0.06 ppmv in the range 380-120 K for ARW. As for UM, the moistening was found to be much larger (about 2.24 ppmv in the range of 380-120 K) than for ARW. This result confirms that convective transport can play an important role in regulating the water vapor mixing ratio in the LS. © 2009 American Meteorological Society."
"6603327182;21735084500;7402469637;6602969645;56283402900;7003726515;","Correlation between equatorial Kelvin waves and the occurrence of extremely thin ice clouds at the tropical tropopause",2008,"10.5194/acp-8-4019-2008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-48249100063&doi=10.5194%2facp-8-4019-2008&partnerID=40&md5=04c9dd8df1ca8d1f192d064fef15895d","A number of field-campaigns in the tropics have been conducted in recent years with two different LIDAR systems at Paramaribo (5.8° N, 55.2° W), Suriname. The lidars detect particles in the atmosphere with high vertical and temporal resolution and are capable of detecting extremely thin cloud layers which frequently occur in the tropical tropopause layer (TTL). Radiosonde as well as operational ECMWF analysis showed that equatorial Kelvin waves propagated in the TTL and greatly modulated its temperature structure. We found a clear correlation between the temperature anomalies introduced by these waves and the occurrence of thin cirrus in the TTL. In particular we found that extremely thin ice clouds form regularly where cold anomalies shift the tropopause to high altitudes. These findings suggest an influence of Kelvin wave activity on the dehydration in the TTL and thus on the global stratospheric water vapour concentration."
"26643250500;7004944088;","Formation of nitric acid/water ice particles in cirrus clouds",2006,"10.1029/2006GL025927","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745434284&doi=10.1029%2f2006GL025927&partnerID=40&md5=7e37632f376189acd60566f7b59ad6d6","Nitric acid (HNO3) in cirrus ice crystals has been measured in the last decade during airborne field campaigns at latitudes 53°S-68°N. The HNO3 content in ice crystals, expressed in terms of HNO3/H2O molar ratio, and the fraction of HNO3 in ice derived from those measurements exhibit a clear upward trend with decreasing temperature. The observations are explained by a novel model describing dissolution of HNO3 in liquid aerosol particles serving as freezing nuclei and subsequent trapping of HNO3 during ice crystal growth. The efficiency of trapping increases with decreasing temperature. Efficient trapping occurs via diffusional burial of the ambient HNO3 below about 203 K, because of long residence times of HNO3 molecules at the ice surface. This opens the possibility for HNO3-induced modifications of processes affecting ice crystal growth. At warmer temperatures, molecular processes in the ice surface layer cause an increasingly rapid escape of adsorbed HNO3 into the gas phase and render trapping less efficient despite faster ice growth rates. Copyright 2006 by the American Geophysical Union."
"10239725000;6701606453;7202899330;57207511394;36929285000;57191522633;26665326700;26643481800;","Simultaneous retrievals of column ozone and aerosol optical properties from direct and diffuse solar irradiance measurements",2005,"10.1029/2004JD005330","https://www.scopus.com/inward/record.uri?eid=2-s2.0-20444463521&doi=10.1029%2f2004JD005330&partnerID=40&md5=3dc7dbf25359a175903f5e631c32c258","A retrieval technique has been developed to simultaneously determine column ozone amounts and aerosol optical properties using surface observations of solar ultraviolet direct normal and diffuse horizontal irradiance from a multifilter rotating shadowband radiometer. The retrieval consists of a Bayesian scheme involving a tropospheric ultraviolet radiative transfer model. The technique was tested using cloud-free observations collected during a Mexico City Metropolitan Area air pollution field campaign from April to May 2003. Retrieval results compared favorably to those of independent techniques, including ozone amounts from a direct-Sun method, Langley-derived aerosol optical depths, and aerosol single-scattering albedos from a direct-to-diffuse irradiance ratio technique. Further comparisons were performed between the measurements and model simulations when using the retrieval results as inputs, both from the proposed technique and the combined independent methods. Simulations using the results of the new method were found to agree with the observations within the assumed limits of measurement and model uncertainty. It is anticipated that the technique will be applied across a 33-site network of radiometers maintained by the U.S. Department of Agriculture UV-B Monitoring and Research Program for development of aerosol climatologies and for providing ground validation for satellite measurements. Copyright 2005 by the American Geophysical Union."
"7103357902;7005174340;6507004778;6701511337;7005228425;","A new tethered balloon-borne payload for fine-scale observations in the cloudy boundary layer",2003,"10.1023/A:1021242305810","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037366951&doi=10.1023%2fA%3a1021242305810&partnerID=40&md5=700c836bf8eb001356a0f735ed62e1f5","A new scientific payload is introduced for fine-scale measurements of meteorological (wind vector, static air temperature, humidity, and air pressure) and microphysical (aerosol particles and cloud droplets) properties, suspended below a tethered balloon. The high resolution sensors and the tethered balloon are described. Measurements in a lifted for layer from a first field campaign are presented. The detailed investigation of the fog/haze and the temperature inversion layer demonstrates the damping influence of the fog on temperature fluctuations, while the wind fluctuations are significantly decreased by the evolving temperature inversion, which was about 30 m above the fog layer. From spectral analysis the noise floors of the high-resolution sensors are determined to 10-6 kg m-3 for the L W C (liquid water content) and 4 mK for the fast temperature sensor (UFT-B). The correlation between temperature and L W C structures in shallow haze layers is investigated. The release of latent heat and the corresponding warming in the haze of about 0.1 K could be quantified."
"7801660069;7005543472;57210538699;7102578937;","Enhanced O3 and NO2 in thunderstorm clouds: Convection or production?",1999,"10.1029/1999GL900243","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033134087&doi=10.1029%2f1999GL900243&partnerID=40&md5=d86bb59c6912cb8449b25468b051dab8","Ground based zenith sky measurements of O3 and NU2 slant optical thickness (SOT) from a field campaign at the Observatoire de Haute Provence in June 1996 are reported. Differential optical absorption spectroscopy in the 450-497 nm region was used to derive SOT for both specics under clear sky, cloudy and thunderstorm conditions. SOT enhancements of 62% for O3 and up to 320% for NO2 are found in a thunderstorm cloud. Interpretation of the measurements was carried out using a radiative transfer model. To explain the measurements a mean increase of 38 ppbv of the in-cloud concentration of Oa has to be assumed. This amount leads to a mean in-cloud concentration of more than 100 ppbv of Oa. The corresponding increase in NU2 is 3 ppbv, resulting in an in-cloud concentration of 3.2 ppbv. The NO2 enhancements are in large part explained by lightning processes. In contrast, the enhanced O3 appears to be induced by intrusion of stratospheric air and possibly ozone production by non-lightning discharge mechanisms. Copyright 1999 by the American Geophysical Union."
"56939103900;7403931916;7006783796;7004364155;56493740900;7005729142;7202057166;","A two-habit model for the microphysical and optical properties of ice clouds",2014,"10.5194/acp-14-13719-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84913574685&doi=10.5194%2facp-14-13719-2014&partnerID=40&md5=72ffbc9bc6ea56ba41d96d8aa9c868d7","To provide a better representation of natural ice clouds, a novel ice cloud model is developed by assuming an ice cloud to consist of an ensemble of hexagonal columns and 20-element aggregates with specific habit fractions at each particle size bin. The microphysical and optical properties of this two-habit model (THM) are compared with both laboratory and in situ measurements, and its performance in downstream satellite remote sensing applications is assessed. The ice water contents and median mass diameters calculated based on the THM closely agree with in situ measurements made during 11 field campaigns. In this study, the scattering, absorption, and polarization properties of ice crystals are calculated with a combination of the invariant imbedding T matrix, pseudo-spectral time domain, and improved geometric-optics methods over an entire practical range of particle sizes. The phase functions, calculated based on the THM, show close agreement with counterparts from laboratory and in situ measurements and from satellite-based retrievals. When the THM is applied to the retrievals of cloud microphysical and optical properties from MODIS (the Moderate Resolution Imaging Spectroradiometer) observations, excellent spectral consistency is achieved; specifically, the retrieved cloud optical thicknesses based on the visible/near infrared bands and the thermal infrared bands agree quite well. Furthermore, a comparison between the polarized reflectivities observed by the PARASOL satellite and from theoretical simulations illustrates that the THM can be used to represent ice cloud polarization properties."
"24173130300;26659155100;7003656857;7006252221;23019327900;","Observational validation of the compensating mass flux through the shell around cumulus clouds",2009,"10.1002/qj.358","https://www.scopus.com/inward/record.uri?eid=2-s2.0-66449115386&doi=10.1002%2fqj.358&partnerID=40&md5=103c935ed4e8900fb8cdd59143d4da3a","The existence of a subsiding shell around cumulus clouds has been observed before in several aircraft measurement campaigns. Recent results from large-eddy simulations (LES) showed that the downward mass flux through the shell compensates for a significant fraction of the upward mass flux through the cloud. In this study, aeroplane measurements from the Rain In Cumulus over the Ocean (RICO) field campaign are used to verify the existence of this compensating mass flux. Just as in the LES results, the in-shell downward mass flux is found to be significant. However, a few differences were found in comparison with the LES results; most of them were explained by taking into account the difference between the two-dimensional slabs in LES and the one-dimensional lines from aeroplane observations. Copyright © 2008 Royal Meteorological Society."
"11839267100;7202772927;55745955800;7006957668;7401936984;7401701196;55718206700;35072928400;57201725986;","A contribution by ice nuclei to global warming",2009,"10.1002/qj.449","https://www.scopus.com/inward/record.uri?eid=2-s2.0-69949170600&doi=10.1002%2fqj.449&partnerID=40&md5=9aebfdfe9a1197f3f25ac1c2543ff69a","Ice nuclei (IN) significantly affect clouds via supercooled droplets, that in turn modulate atmospheric radiation and thus climate change. Since the IN effect is relatively strong in stratiform clouds but weak in convective ones, the overall effect depends on the ratio of stratiform to convective cloud amount. In this paper, ten years of TRMM (Tropical Rainfall Measuring Mission) satellite data are analyzed to confirm that stratiform precipitation fraction increases with increasing latitude, which implies that the IN effect is stronger at higher latitudes. To quantitatively evaluate the IN effect versus latitude, large-scale forcing data from ten field campaigns are used to drive a cloud-resolving model to generate long-term cloud simulations. As revealed in the simulations, the increase in the net downward radiative flux at the top of the atmosphere from doubling the current IN concentrations is larger at higher latitude, which is attributed to the meridional tendency in the stratiform precipitation fraction. Surface warming from doubling the IN concentrations, based on the radiative balance of the globe, is compared with that from anthropogenic CO2. It is found that the former effect is stronger than the latter in middle and high latitudes but not in the Tropics. With regard to the impact of IN on global warming, there are two factors to consider: the radiative effect from increasing the IN concentration and the increase in IN concentration itself. The former relies on cloud ensembles and thus varies mainly with latitude. In contrast, the latter relies on IN sources (e.g. the land surface distribution) and thus varies not only with latitude but also longitude. Global desertification and industrialization provide clues on the geographic variation of the increase in IN concentration since pre-industrial times. Thus, their effect on global warming can be inferred and can then be compared with observations. A general match in geographic and seasonal variations between the inferred and observed warming suggests that IN may have contributed positively to global warming over the past decades, especially in middle and high latitudes. © 2009 Royal Meteorological Society."
"11440520800;6506454031;8700289500;7007009060;36645896500;","Isokinetic TWC evaporator probe: Development of the IKP2 and performance testing for the HAIC-HIWC darwin 2014 and cayenne-2015 field campaigns",2016,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979955525&partnerID=40&md5=90a9661daa2a31601dd44a5da5ad4298","A new Isokinetic Total Water Content Evaporator (IKP2) was downsized from a prototype instrument, specifically to make airborne measurements of hydrometeor total water content (TWC) in deep tropical convective clouds to assess the new ice crystal Appendix D icing envelope. The probe underwent numerous laboratory and wind tunnel investigations to ensure reliable operation under the difficult high altitude/speed/TWC conditions under which other TWC instruments have been known to either fail, or have unknown performance characteristics. The article tracks the testing and modifications of the IKP2 probe to ensure its readiness for three flight campaigns in 2014 and 2015. Comparisons are made between the IKP2 and the NASA Icing Research Tunnel reference values in liquid conditions, and to an exploratory technique estimating ice water content from a bulk ice capture cylinder method in glaciated conditions. These comparisons suggest that the initial target of 20% accuracy in TWC has been achieved and likely exceeded for tested TWC values in excess of about 0. 5 gm-3. Uncertainties in the ice water content reference method have been identified. Complications are introduced in the necessary subtraction of an independently measured background water vapour concentration, errors of which are small at the colder flight temperatures, but increase rapidly with increasing temperature, and ultimately limit the practical use of the instrument in a tropical convective atmosphere to conditions colder than about 0 C. A companion article in this conference traces the accuracy of the components of the IKP2 to derive estimated system accuracy. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA."
"36133941900;6602137606;18134195800;12645700600;55196799200;7005432249;","Influence of aerosols on the life cycle of a radiation fog event. A numerical and observational study",2015,"10.1016/j.atmosres.2014.04.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910069929&doi=10.1016%2fj.atmosres.2014.04.013&partnerID=40&md5=448782e18b9eb60df91ed66640a16e54","Despite the knowledge gained on the physical processes dominating the formation, development and dissipation of radiation fog events, uncertainties still exist about the role of the microphysical processes related to aerosol characteristics. The objective of this work is to analyze the sensitivity of fog to aerosols through their impacts on the fog droplets. A radiation fog event that formed on 15/11/2011 at the SIRTA Observatory near Paris in the context of the 2011-2012 ParisFog field campaign is the basis of this study. The selected case is one that initially forms a few hundred meters above the surface and within half an hour lowers down to the surface. A combination of SIRTA's sophisticated observations and 1D numerical simulations is employed with the aim of better understanding the influence of thermodynamics and microphysics on the life-cycle of the fog event and the degree to which aerosol characteristics such as concentration of potentially activated aerosols, size and solubility affect its characteristics. It results that the model simulates fairly well the fog life cycle, with only one half hour advance in the onset and one hour in the dissipation at the surface. The quality of the reference simulation is evaluated against several in-situ and remote sensing measurements. A numerical sensitivity analysis shows that the fog characteristics are strongly influenced by the aerosols. Doubling (halving) the cloud condensation nuclei (CCN) number translates into a 160% increase (65% decrease) in the production of fog droplets, and a 60% increase (40% decrease) of the liquid water path (LWP). The aerosols influence up to 10% the fog geometrical thickness. The necessity for more detailed local forcings that will produce better thermohygrometric conditions in the upper levels above the formed fog layer is underlined, as well as the addition of microphysical measurements in the vertical that will allow to improve two-moment microphysics schemes. © 2014 Elsevier B.V."
"35113492400;24765069600;56611366900;6701333444;","Empirical relationship between entrainment rate and microphysics in cumulus clouds",2013,"10.1002/grl.50445","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879903023&doi=10.1002%2fgrl.50445&partnerID=40&md5=7b91b3f367794253c2f39bd050a5c22e","The relationships between fractional entrainment rate and key microphysical quantities (e.g., liquid water content, droplet number concentration, volume mean radius, and standard deviation of cloud droplet size distributions) in shallow cumuli are empirically examined using in situ aircraft observations from the Routine Atmospheric Radiation Measurement Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign over the Atmospheric Radiation Measurement Southern Great Plains site. The results show that the microphysical quantities examined generally exhibit strong relationships with entrainment rate and that the relationships collectively suggest the dominance of homogeneous entrainment mixing, which is unfavorable to the formation of large droplets and the initiation of warm rain in the clouds. The dominance of the homogeneous mixing mechanism is further substantiated by the dependency on entrainment rate of relationships among various microphysical variables and of cloud droplet size distributions. The dominance of this mechanism is also quantitatively confirmed by examining the degree of homogeneous mixing in the clouds. The dominance of homogeneous mixing may be an important reason why none of the cumulus clouds studied was drizzling. © 2013 American Geophysical Union. All Rights Reserved."
"6507198695;36559769700;7202967741;24281680700;7801595201;26653350000;6604005739;7404661626;7006978226;","Year-round radiocarbon-based source apportionment of carbonaceous aerosols at two background sites in South Asia",2012,"10.1029/2011JD017161","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861709851&doi=10.1029%2f2011JD017161&partnerID=40&md5=9b2c855e40d4d8868f8858d6f331e028","Atmospheric Brown Clouds (ABC), regional-scale haze events, are a significant concern for both human cardiopulmonary health and regional climate impacts. In order to effectively mitigate this pollution-based phenomenon, it is imperative to understand the magnitude, scope and source of ABC in regions such as South Asia. Two sites in S. Asia were chosen for a 15-month field campaign focused on isotope-based source apportionment of carbonaceous aerosols in 2008-2009. Both the Maldives Climate Observatory in Hanimaadhoo (MCOH) and a mountaintop site in Sinhagad, India (SINH) act as regionally mixed receptor sites. Annual radiocarbon-based source apportionment for soot elemental carbon (SEC) at MCOH and SINH revealed 73 6% and 59 5% contribution from biomass combustion, respectively (remainder from fossil fuel). The contributions from biogenic/biomass combustion to total organic carbon were similar between MCOH and SINH (69 5% and 64 5, respectively). The biomass combustion contribution for SEC in the current study, especially the results from MCOH, shows good agreement with published black carbon emissions inventories for India. Geographic source assessment, including clustered back trajectory analysis and carbon contribution by source region, indicated that the highest SEC/TOC loads originated from the W. Indian coastal margin, including the coastal city of Mumbai, India. The winter dry season 14C-based source apportionment of the BC-tracing SEC fraction for 2006, 2008, 2009 were not statistically different (p = 0.7) and point to a near-constant two-thirds contribution from biomass combustion practices, including wood and other biofuels as well as burning of agricultural crop residues. © Copyright 2012 by the American Geophysical Union."
"23667190900;57204253860;","Anvil characteristics as seen by C-POL during the Tropical Warm Pool International Cloud Experiment (TWP-ICE)",2008,"10.1175/2007MWR2068.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-39749141643&doi=10.1175%2f2007MWR2068.1&partnerID=40&md5=864aca16e4af9fd7c2a87f42328ee0eb","The Tropical Pacific Warm Pool International Cloud Experiment (TWP-ICE) took place in Darwin, Australia, in early 2006. C-band radar data were used to characterize tropical anvil (i.e., thick, nonprecipitating cloud associated with deep convection) areal coverage, height, and thickness during the month-long field campaign. The morphology, evolution, and longevity of the anvil were analyzed, as was the relationship of the anvil to the rest of the precipitating system. The anvil was separated into mixed (i.e., echo base below 6 km) and ice-only categories. The average areal coverage for each anvil type was between 4% and 5% of the radar grid. Ice anvil thickness averaged 2.8 km and mixed anvil thickness averaged 6.7 km. Areal peaks show that mixed anvil typically formed out of the stratiform rain region. Peak production in ice anvil usually followed the mixed anvil peak by 1-3 h. Anvil typically lasted 4-10 h after the initial convective rain area peak. TWP-ICE experienced three distinct regimes: an active monsoon, a dry monsoon, and a break period. During the experiment (except the active monsoon period) there was a strong negative correlation between ice anvil thickness and ice anvil height, a strong positive correlation between ice anvil area and thickness, and a greater variance in ice anvil bottom than ice anvil top. These results have important implications for understanding how anvil affects the tropical atmosphere. © 2008 American Meteorological Society."
"6507731482;6505932008;25953950400;","Impacts of nucleating aerosol on anvil-cirrus clouds: A modeling study",2007,"10.1016/j.atmosres.2006.06.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33847388492&doi=10.1016%2fj.atmosres.2006.06.002&partnerID=40&md5=75d56c1e67b6ae4e23ec05992d69db41","This paper examines the potential effects of Saharan dust intrusions on the microphysical structure and optical properties of anvil-cirrus clouds. A series of 3-D LES simulations were initialized and forced by output data from mesoscale simulations in a previous study, in which we analyzed the impact of the enhanced low-level concentrations of cloud-nucleating aerosols on the characteristics of convective storms. The effects of enhancing aerosol concentrations on the ice-particle size distributions as well as some of their moments were analyzed as the LES model domain followed the trajectory of the simulated cirrus cloud. The experimental design was based on aerosol concentrations observed over the peninsula of Florida toward the end of the CRYSTAL-FACE field campaign held during July 2002. Results indicate that variations in the concentrations of nucleation aerosols have a significant effect on the optical properties and lifetime of cirrus anvil clouds. In addition, enhancing low-level aerosols can affect the radiation budget, leading to surface radiative cooling. Both IFN and CCN enhancements show important effects; however, results suggest that CCN and GCCN play a more dominant role. © 2006 Elsevier B.V. All rights reserved."
"57218944625;6603860837;","Precipitation profile retrievals using temperature-sounding microwave observations",2003,"10.1029/2003jd003572","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1342291013&doi=10.1029%2f2003jd003572&partnerID=40&md5=0f664b135e7dd99c5f91049f9b2c874c","A Bayesian retrieval algorithm was developed to demonstrate the potential of microwave temperature-sounding channels for precipitation profile retrieval from spaceborne observations. The algorithm uses a database from combined cloud-radiative transfer model simulations of Hurricane Bonnie which was observed during the field campaign Convection and Moisture Experiment 3 (CAMEX-3). Sounding channels from two oxygen absorption complexes at 50-57 GHz and 118.75 GHz were combined to make use of their differential response to absorption and scattering by hydrometeors. The retrieval method was applied to airborne observations with the National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Aircraft Sounder Testbed-Microwave (NAST-M) radiometer on board the ER 2 aircraft. The retrieved profiles were used to simulate radar reflectivities to be compared to ER 2 Doppler observations from the same aircraft. The results lead to the following conclusions: (1) The sounding channels provide the unique potential of cloud slicing because the channel-dependent variation of clear-air absorption allows the adjustment of maximum sensitivity to different altitudes. (2) The validation with radar data indicates a good performance of the algorithm; however, at least four channels in each absorption complex are required to constrain the retrieval well enough with the observations. (3) The validation also shows that even though a Hurricane Bonnie cloud model simulation was used, the simulated database does not represent the observations very well. (4) The database may bias the retrievals by the underlying assumptions on temperature, humidity, and hydrometeor distributions. Sounding channels are more sensitive to a possible temperature bias in the database. While this bias can be corrected, the retrievals forward the database bias to the retrieved products independent of sensor. For global applications, more flexible retrieval approaches are required that are capable of constraining the algorithm according to the local situation. © 2003 by the American Geophysical Union."
"9537045600;7004114883;7403352662;7406215388;","Constaining microwave brightness temperatures by radar brightband observations",2003,"10.1175/1520-0426(2003)020<0856:CMBTBR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037932679&doi=10.1175%2f1520-0426%282003%29020%3c0856%3aCMBTBR%3e2.0.CO%3b2&partnerID=40&md5=f5e3293fb73715989f38e0b7f7807ba3","Multichannel microwave sensors make it possible to construct physically based rainfall retrieval algorithms. In these schemes, errors arising from the inaccuracy of the physical modeling of the cloud system under observation have to be accounted for. The melting layer has recently been identified as a possible source of bias when stratiform events are considered. In fact, Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) observations reveal systematic differences in the observed brightness temperatures between similar rain profiles that often differ only by the presence or absence of a bright band. A sensitivity study of the scattering properties of the melting layer with different one-dimensional steady-state microphysical and electromagnetic models is performed. The electromagnetic modeling of the ice particle density and assumption of the ventilation coefficient parameterization is found to have the greatest impact on the extinction profiles. Data taken from a 0.915-GHz National Oceanic and Atmospheric Administration (NOAA) profiler during the Kwajalein Experiment (KWAJEX) field campaign are used to reduce the uncertainties in the modeling of the bright band. The profiler data reduce the number of viable parameterizations, which in turn leads to a reduction in the variability of the upwelling radiances (simulated at TMI angle) for different cloud simulations. Using the parameterizations that best match the profiler data, the brightness temperatures TH generally increase if mixed-phase precipitation is included in the model atmosphere. The effect is most pronounced for systems with low freezing levels, such as a midlatitude cold front simulation. For TMI footprints at 10.65 GHz. the increase in the TB from the bright band generally increases with rain rate and changes by as much as ∼15-20 K. At 19.35 GHz the maximum effect is found around 3-5 mm h-1 (∼15 K), and at 37 GHz the maximum effect is around 1 mm h-1 (∼10 K), while at 85.5 GHz the effect is always lower than 3 K. Despite the reduction of uncertainties achieved by using 915-MHz profiler data, differences between parameterizations are still significant, especially for the higher TMI frequencies. A validation experiment is proposed to solve this issue and to further reduce the uncertainties in brightband modeling."
"55800936800;14034301300;7403401100;55196799200;57202475063;17434636400;7801565183;12645700600;7004393835;7005069415;7006434689;","Size-dependent particle activation properties in fog during the ParisFog 2012/13 field campaign",2014,"10.5194/acp-14-10517-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907930078&doi=10.5194%2facp-14-10517-2014&partnerID=40&md5=aba14682ccd783547ff7930277b98737","Fog-induced visibility reduction is responsible for a variety of hazards in the transport sector. Therefore there is a large demand for an improved understanding of fog formation and thus improved forecasts. Improved fog forecasts require a better understanding of the numerous complex mechanisms during the fog life cycle. During winter 2012/13 a field campaign called ParisFog aiming at fog research took place at SIRTA (Instrumented Site for Atmospheric Remote Sensing Research). SIRTA is located about 20 km southwest of the Paris city center, France, in a semi-urban environment. In situ activation properties of the prevailing fog were investigated by measuring (1) total and interstitial (non-activated) dry particle number size distributions behind two different inlet systems; (2) interstitial hydrated aerosol and fog droplet size distributions at ambient conditions; and (3) cloud condensation nuclei (CCN) number concentration at different supersaturations (SS) with a CCN counter. The aerosol particles were characterized regarding their hygroscopic properties, fog droplet activation behavior and contribution to light scattering for 17 developed fog events. Low particle hygroscopicity with an overall median of the hygroscopicity parameter, &kappa;, of 0.14 was found, likely caused by substantial influence from local traffic and wood burning emissions. Measurements of the aerosol size distribution at ambient RH revealed that the critical wet diameter, above which the hydrated aerosols activate to fog droplets, is rather large (with a median value of 2.6&mu;m) and is highly variable (ranging from 1 to 5&mu;m) between the different fog events. Thus, the number of activated fog droplets was very small and the non-activated hydrated particles were found to contribute significantly to the observed light scattering and thus to the reduction in visibility. Combining all experimental data, the effective peak supersaturation, SSpeak, a measure of the peak supersaturation during the fog formation, was determined. The median SSpeak value was estimated to be in the range from 0.031 to 0.046% (upper and lower limit estimations), which is in good agreement with previous experimental and modeling studies of fog. © 2014 Author(s)."
"54784169900;16308514000;55481275400;37021250300;37021577900;55480310900;6701378450;7101846027;7006572336;57196499374;","Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California",2014,"10.1002/2013JD021228","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84903289280&doi=10.1002%2f2013JD021228&partnerID=40&md5=8827722f548151c783be25b5fdb41f64","During the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) and 2013 Nucleation in California Experiment (NiCE) field campaigns, a predominantly organic aerosol (> 85% by mass) was observed in the free troposphere over marine stratocumulus off the coast of California. These particles originated from a densely forested region in the Northwestern United States. The organic mass spectrum resolved by positive matrix factorization is consistent with the mass spectra of previously measured biogenic organic aerosol. Particulate organic mass exhibits a latitudinal gradient that corresponds to the geographical distribution of vegetation density and composition, with the highest concentration over regions impacted by densely populated monoterpene sources. Due to meteorological conditions during summer months, cloud-clearing events transport aerosol from the Northwestern United States into the free troposphere above marine stratocumulus. Based on the variation of meteorological variables with altitude, dry air containing enhanced biogenic organic aerosol is shown to entrain into the marine boundary layer. Fresh impacts on cloud water composition are observed north of San Francisco, CA which is consistent with fresh continental impacts on the marine atmosphere at higher latitudes. Continental aerosol size distributions are bimodal. Particles in the 100 nm mode are impacted by biogenic sources, while particles in the ∼ 30 nm mode may originate from fresh biogenic emissions. Continental aerosol in the 100 nm mode is cloud condensation nuclei active and may play a role in modulating marine stratocumulus microphysics. © 2014. American Geophysical Union. All Rights Reserved."
"35113492400;56611366900;24765069600;6701333444;","Observed impacts of vertical velocity on cloud microphysics and implications for aerosol indirect effects",2012,"10.1029/2012GL053599","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84869409594&doi=10.1029%2f2012GL053599&partnerID=40&md5=bc5ebc16dc7a540b6d1d6a25f9952000","The simultaneous measurements of vertical velocity and cloud droplet size distributions in cumuli collected during the RACORO field campaign over the Atmospheric Radiation Measurement Program's Southern Great Plains site near Lamont, Oklahoma, US, are analyzed to determine the effects of vertical velocity on droplet number concentration, relative dispersion (the ratio of standard deviation to mean radius), and their relationship. The results show that with increasing vertical velocity the droplet number concentration increases while the relative dispersion decreases. The data also exhibit a negative correlation between relative dispersion and droplet number concentration. These empirical relationships can be fitted well with power law functions. This observational study confirms the theoretical and numerical expectations of the effects of vertical velocity on cloud microphysics by analyzing the data of vertical velocity directly. The effects of vertical velocity on relative dispersion and its relationship with droplet number concentration are opposite to that associated with aerosol loading, posing a confounding challenge for separating aerosol indirect effects from dynamical effects. © 2012. American Geophysical Union. All Rights Reserved."
"6506416572;23017945100;6602417968;6701754792;35305025100;26421356200;","Microphysical characterisation of West African MCS anvils",2010,"10.1002/qj.557","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949358975&doi=10.1002%2fqj.557&partnerID=40&md5=2db0c159be93872521dc227956ef67c7","Deep convection in the Tropics is the source of large tropospheric extended clouds usually called anvils. These anvils may produce precipitation (stratiform region of deep convective storms), and also cirrus shields persisting from several hours to several days. Anvils impact the radiation budget, they induce a storage term in the whole water budget which is still relatively poorly quantified, and dynamical feedbacks may be induced in the upper troposphere. The AMMA field campaign which was held over West Africa during the 2006 wet season provided a unique opportunity to document the microphysics of these anvils from unprecedented airborne observations. Airborne in situ measurements of ice crystals and observations from a 95 GHz Doppler radar are used to characterize the microphysical properties of tropical anvils. The dataset is binned into stratiform and cirriform regions. Some data in the stratiform regions were likely obtained close enough to convective cores that the particles may have grown primarily within those cores. The data obtained over the continent and over the ocean are also characterized separately. Particle habit and growth processes are inferred from an examination of the collected particle images, from quantitative comparisons of 95 GHz reflectivities calculated from the in situ microphysical observations with the measured radar reflectivities, and from a statistical analysis of the two-dimensional particle images. The predominant precipitation particles above the 0°C isotherm in the stratiform anvil region are rimed aggregates. These rimed aggregates seem to get less dense and of smaller diameter when moving rearward of the system towards the cirriform region. The retrieved density laws (assumed to be power laws) lie close to the relationship for rimed particles of Locatelli and Hobbs. Particle size distributions in tropical anvils are also studied. The exponential shape seems to be a good approximation for these particle size distributions overall. The decrease in concentration with diameter is also found to be faster for cirriform regions than for stratiform regions. Normalising these particle size distributions produces a relatively invariant shape (in agreement with earlier studies), with however an increased variability for the smallest and largest values of the normalised diameter. The characterisation of the bulk microphysical properties using these in situ microphysical observations shows that the ice water content, the effective radius and the reflectivity-weighted fall velocity generally increase with air temperature, in agreement with earlier studies. These parameters are found to be systematically smaller on average in cirriform regions than in stratiform regions, and this is true at all temperatures. These values are then compared with statistical relationships used in cloud-resolving models and general circulation models, since a realistic representation of microphysics in models is very important to understand not only the processes at work, but the dynamical feedbacks and effects on climate. Large differences are found, the current parametrizations being unable to reproduce the large values of the considered microphysical parameters. © 2010 Royal Meteorological Society."
"6701689811;6508063123;25926681100;35577097300;24605747000;","Vertical distribution of aerosols over the east coast of India inferred from airborne LIDAR measurements",2009,"10.5194/angeo-27-4157-2009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70749149051&doi=10.5194%2fangeo-27-4157-2009&partnerID=40&md5=a9324dca39955328f94689be7f74bce9","The information on altitude distribution of aerosols in the atmosphere is essential in assessing the impact of aerosol warming on thermal structure and stability of the atmosphere. In addition, aerosol altitude distribution is needed to address complex problems such as the radiative interaction of aerosols in the presence of clouds. With this objective, an extensive, multi-institutional and multi-platform field experiment (ICARB-Integrated Campaign for Aerosols, gases and Radiation Budget) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP) over continental India and adjoining oceans during March to May 2006. Here, we present airborne LIDAR measurements carried out over the east Coast of the India during the ICARB field campaign. An increase in aerosol extinction (scattering + absorption) was observed from the surface upwards with a maximum around 2 to 4 km. Aerosol extinction at higher atmospheric layers (gt;2 km) was two to three times larger compared to that of the surface. A large fraction (75-85%) of aerosol column optical depth was contributed by aerosols located above 1 km. The aerosol layer heights (defined in this paper as the height at which the gradient in extinction coefficient changes sign) showed a gradual decrease with an increase in the offshore distance. A large fraction (60-75%) of aerosol was found located above clouds indicating enhanced aerosol absorption above clouds. Our study implies that a detailed statistical evaluation of the temporal frequency and spatial extent of elevated aerosol layers is necessary to assess their significance to the climate. This is feasible using data from space-borne lidars such as CALIPSO, which fly in formation with other satellites like MODIS AQUA and MISR, as part of the A-Train constellation."
"7405460591;6603379144;7103100609;7201799748;9336087000;","Further evidences of deep convective vertical transport of water vapor through the tropopause",2009,"10.1016/j.atmosres.2009.06.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349411532&doi=10.1016%2fj.atmosres.2009.06.018&partnerID=40&md5=82cf99f6bfbe4b2e919cf56e0ade3f49","A few years ago, we identified a deep convective transport mechanism, of water vapor through the tropopause, namely, storm top gravity wave breaking, such that tropospheric water substance can be injected into the lower stratosphere via this pathway. The main evidence presented previously was taken from the lower resolution AVHRR images of the storm anvil top cirrus plumes obtained by polar orbiting satellites. Recent observations have provided further supporting evidence for this important cross-tropopause transport mechanism. There are now many higher resolution satellite images, mainly from MODIS instrument, that show more definitely the existence of these plumes, many of which would probably be unseen by lower resolution images. Furthermore, a thunderstorm movie taken in Denver (USA) area during STEPS2000 field campaign and another thunderstorm movie taken by a building top webcam in Zurich also demonstrate that the jumping cirrus phenomenon, first identified by T. Fujita in 1980s, may be quite common in active thunderstorm cells, quite contrary to previous belief that it is rare. We have used a cloud model to demonstrate that the jumping cirrus is exactly the gravity wave breaking phenomenon that transports water vapor through the tropopause. These additional evidences provide increasing support that deep convection contributes substantially to the troposphere-to-stratosphere transport of water substance. This corroborates well with recent studies of the stratospheric HDO/H2O ratio which is much highly than it would be if the transport is via slow ascent. The only explanation that can be used to interpret this observation at present is that water substance is transported through the tropopause via rapid vertical motion, i.e., deep convection. © 2009 Elsevier B.V."
"36856321600;7004479957;","Large eddy simulation of the diurnal cycle in southeast pacific stratocumulus",2009,"10.1175/2008JAS2785.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65549168351&doi=10.1175%2f2008JAS2785.1&partnerID=40&md5=df1b942c495b7e9d2e601416aca0b324","This paper describes a series of 6-day large eddy simulations of a deep, sometimes drizzling stratocumulus-topped boundary layer based on forcings from the East Pacific Investigation of Climate (EPIC) 2001 field campaign. The base simulation was found to reproduce the observed mean boundary layer properties quite well. The diurnal cycle of liquid water path was also well captured, although good agreement appears to result partially from compensating errors in the diurnal cycles of cloud base and cloud top due to overentrainment around midday. At all times of the day, entrainment is found to be proportional to the vertically integrated buoyancy flux. Model stratification matches observations well; turbulence profiles suggest that the boundary layer is always at least somewhat decoupled. Model drizzle appears to be too sensitive to liquid water path and subcloud evaporation appears to be too weak. Removing the diurnal cycle of subsidence had little effect on simulated liquid water path. Simulations with changed droplet concentration and drizzle susceptibility showed large liquid water path differences at night, but differences were quite small at midday. Droplet concentration also had a significant impact on entrainment, primarily through droplet sedimentation feedback rather than through drizzle processes. © 2009 American Meteorological Society."
"14037284600;7402642949;","An upper threshold of enhanced global shortwave irradiance in the troposphere derived from field measurements in tropical mountains",2008,"10.1175/2008JAMC1861.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65349187129&doi=10.1175%2f2008JAMC1861.1&partnerID=40&md5=3e50f1dce430dbbc52472715efc27e5f","Extraordinarily high values of global irradiance (up to 1832 W m-22) incident upon a horizontal surface were observed during a 4-yr meteorological field campaign in the southern Ecuadorian Andes Mountains (4°S). The unexpected magnitude gave rise to a thorough revision of the instrumentation and an assessment of the radiation database. Infrastructure at the sites and software were critically examined, and the sensor and datalogger manufacturers were contacted. The observed enhanced irradiance was quantified with a simple clear-sky model for global radiation. The efforts showed that atmospheric conditions and not artifacts had produced the high values. Cloud radiative effects could be singled out as the exclusive source of the ""superirradiance."" Mean (bihourly) maximum enhancement was 119.6% of the potential (clear sky) irradiance; absolute maximum enhancement occasionally reached to over 170%. Thereby, under ideal conditions, the upper threshold of global irradiance is apparently ∼200% of the potential (clear sky) direct radiation [i.e., at the point of observation, downwelling diffuse cloud radiation can (almost) equal the magnitude of its apparent ""source""]. The observations were made between altitudes of 1500 and 3400 m MSL in different climates ranging from perhumid to semiarid (i.e., in very cloudy climates and in less cloudy climates). The conditions that were found to explain the magnitude of the extremely enhanced irradiance are not confined to tropical or mountainous environments only, but rather they can occur at any spot in the troposphere where clouds exist. Therefore, the findings appear to be of general validity. © 2008 American Meteorological Society."
"35572096100;7007108728;7003535385;6603734019;25941200000;","In situ measurements of liquid water content profiles in midlatitude stratiform clouds",2007,"10.1002/qj.147","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36749003907&doi=10.1002%2fqj.147&partnerID=40&md5=47a3d5fb2f8e86c3eae64e35927501be","Statistical characteristics of 584 liquid water content (LWC) profiles collected mainly in midlatitude supercooled stratiform frontal clouds during five field campaigns are presented. It has been found that the majority (55%) of liquid layers have thickness less than 500 m and the depth of these layers decreases with decreasing temperature. LWC profiles for thin cloud layers are usually close to quasi-adiabatic, whereas for thick clouds they are approximately constant with an average LWC value close to 0.14 g m-3. Good agreement was observed between cumulative distributions for liquid water paths derived from in situ LWC profiles and those inferred in previous experiments from ground-based 37 GHz radiometers. Copyright © 2007 Crown in the right of Canada. Published by John Wiley &amp; Sons, Ltd."
"7401876682;57210742979;7202554609;57212761650;","Microphysical observations of warm cumulus clouds in Ceara, Brazil",2000,"10.1016/S0169-8095(00)00045-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033942603&doi=10.1016%2fS0169-8095%2800%2900045-4&partnerID=40&md5=2938fd072366912604afb5d255be1571","Microphysical properties of shallow, warm cumulus clouds, such as droplet concentration, shape of the spectra, etc., may vary due to several factors, from the large-scale environment to microphysical processes on very small scales. Microphysical characteristics of clouds present a significant variability due to different CCN sources. For instance, it is well known that there are crucial differences between maritime and continental clouds regarding their microstructure. In this paper, we analyze microphysical data obtained inside shallow cumuli with an instrumented aircraft in Ceara State, Northeast Brazil, during a field campaign carried out during the first half of 1994. A brief description of the field campaign is presented and a cloud classification is established. Significant differences regarding droplet concentration and spectrum shape were observed among four different cloud regimes: maritime, coastal, continental and 'urban' clouds. Different functions were examined (exponential, gamma, lognormal and Weibull) in order to determine how appropriate are bulk parameterizations of droplet spectra in the representation of the microphysical properties of shallow cumulus clouds. The exponential distribution was shown to be unsuitable for most of the observed spectra. The gamma and lognormal distributions were better with the Weibull distribution providing the best fit. However, a significant variability of the width (or shape) parameter was verified for the three distributions, regarding different cloud regimes (maritime, coastal, continental and urban), from cloud to cloud, and in association with different regions of a cloud. Such variability imposes important limitations to bulk-microphysical modeling using distributions with prescribed width/shape parameters. A brief discussion is presented on how physical processes in a cloud can alter the shape of the droplet spectra, focusing on idealized distributions. (C) 2000 Elsevier Science B.V. All rights reserved."
"6701757092;6504509777;7102141244;","The size distribution of primary biological aerosol particles in cloud water on the mountain Kleiner Feldberg/Taunus (FRG)",2000,"10.1016/S0169-8095(00)00039-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034101073&doi=10.1016%2fS0169-8095%2800%2900039-9&partnerID=40&md5=9073fab39865e0a86ff68efe8ecaf931","During the field campaign, FELDEX 95 cloud water samples were collected and the insoluble particles were analysed by single particle analysis in order to determine the content of primary biological aerosol particles (PBAP). It is found that 25% of the total insoluble particles are biological ones. During cloud events with increasing wind velocity, the concentration of biological particles also increases. Anthropogenic influence leads to a higher amount of both total and biological particles. Within the size distribution, the percentage of biological particles decreases with increasing radius. (C) 2000 Elsevier Science B.V. All rights reserved."
"6603689369;57209647985;7004166136;55408314400;54386827800;7202252296;35263854800;35498837200;7007043918;7409757437;55951799400;57190140560;57208649181;55561824400;7801659989;7201432984;55187246200;55838509940;7003415001;7401651197;57126848900;7202967890;8884524100;36774504400;57195673046;57195869255;6508356419;6507681524;54389550400;7202429440;55619886800;35396858200;6602900485;56210720700;7003729315;7005891596;55545601500;7005967755;6602137800;7005022197;56083852600;7202706097;6602356428;57214667803;18134565600;","The North Atlantic Aerosol and Marine Ecosystem Study (NAAMES): Science motive and mission overview",2019,"10.3389/fmars.2019.00122","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064653919&doi=10.3389%2ffmars.2019.00122&partnerID=40&md5=faa10eb619e8c596184ecd7961a1ca5b","The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) is an interdisciplinary investigation to improve understanding of Earth's ocean ecosystem-aerosol-cloud system. Specific overarching science objectives for NAAMES are to (1) characterize plankton ecosystem properties during primary phases of the annual cycle and their dependence on environmental forcings, (2) determine how these phases interact to recreate each year the conditions for an annual plankton bloom, and (3) resolve how remote marine aerosols and boundary layer clouds are influenced by plankton ecosystems. Four NAAMES field campaigns were conducted in the western subarctic Atlantic between November 2015 and April 2018, with each campaign targeting specific seasonal events in the annual plankton cycle. A broad diversity of measurements were collected during each campaign, including ship, aircraft, autonomous float and drifter, and satellite observations. Here, we present an overview of NAAMES science motives, experimental design, and measurements. We then briefly describe conditions and accomplishments during each of the four field campaigns and provide information on how to access NAAMES data. The intent of this manuscript is to familiarize the broad scientific community with NAAMES and to provide a common reference overview of the project for upcoming publications. © 2019 Behrenfeld, Moore, Hostetler, Graff, Gaube, Russell, Chen, Doney, Giovannoni, Liu, Proctor, Bolaños, Baetge, Davie-Martin, Westberry, Bates, Bell, Bidle, Boss, Brooks, Cairns, Carlson, Halsey, Harvey, Hu, Karp-Boss, Kleb, Menden-Deuer, Morison, Quinn, Scarino, Anderson, Chowdhary, Crosbie, Ferrare, Hair, Hu, Janz, Redemann, Saltzman, Shook, Siegel, Wisthaler, Martin and Ziemba."
"56553589800;57214103245;7102745183;","Scoping a field experiment: Error diagnostics of TRMM precipitation radar estimates in complex terrain as a basis for IPHEx2014",2015,"10.5194/hess-19-1501-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84925665401&doi=10.5194%2fhess-19-1501-2015&partnerID=40&md5=4875091a2e93e9501d6f51ce9d0b6021","A diagnostic analysis of the space-time structure of error in quantitative precipitation estimates (QPEs) from the precipitation radar (PR) on the Tropical Rainfall Measurement Mission (TRMM) satellite is presented here in preparation for the Integrated Precipitation and Hydrology Experiment (IPHEx) in 2014. IPHEx is the first NASA ground-validation field campaign after the launch of the Global Precipitation Measurement (GPM) satellite. In anticipation of GPM, a science-grade high-density raingauge network was deployed at mid to high elevations in the southern Appalachian Mountains, USA, since 2007. This network allows for direct comparison between ground-based measurements from raingauges and satellite-based QPE (specifically, PR 2A25 Version 7 using 5 years of data 2008-2013). Case studies were conducted to characterize the vertical profiles of reflectivity and rain rate retrievals associated with large discrepancies with respect to ground measurements. The spatial and temporal distribution of detection errors (false alarm, FA; missed detection, MD) and magnitude errors (underestimation, UND; overestimation, OVR) for stratiform and convective precipitation are examined in detail toward elucidating the physical basis of retrieval error. The diagnostic error analysis reveals that detection errors are linked to persistent stratiform light rainfall in the southern Appalachians, which explains the high occurrence of FAs throughout the year, as well as the diurnal MD maximum at midday in the cold season (fall and winter) and especially in the inner region. Although UND dominates the error budget, underestimation of heavy rainfall conditions accounts for less than 20% of the total, consistent with regional hydrometeorology. The 2A25 V7 product underestimates low-level orographic enhancement of rainfall associated with fog, cap clouds and cloud to cloud feeder-seeder interactions over ridges, and overestimates light rainfall in the valleys by large amounts, though this behavior is strongly conditioned by the coarse spatial resolution (5 km) of the topography mask used to remove ground-clutter effects. Precipitation associated with small-scale systems (< 25 km2) and isolated deep convection tends to be underestimated, which we attribute to non-uniform beam-filling effects due to spatial averaging of reflectivity at the PR resolution. Mixed precipitation events (i.e., cold fronts and snow showers) fall into OVR or FA categories, but these are also the types of events for which observations from standard ground-based raingauge networks are more likely subject to measurement uncertainty, that is raingauge underestimation errors due to undercatch and precipitation phase. Overall, the space-time structure of the errors shows strong links among precipitation, envelope orography, landform (ridge-valley contrasts), and a local hydrometeorological regime that is strongly modulated by the diurnal cycle, pointing to three major error causes that are inter-related: (1) representation of concurrent vertically and horizontally varying microphysics; (2) non-uniform beam filling (NUBF) effects and ambiguity in the detection of bright band position; and (3) spatial resolution and ground-clutter correction. © Author(s) 2015."
"26632168400;57206503877;7006303509;6506458269;55214879200;55663817800;7101959253;","Impact of large-scale dynamics on the microphysical properties of midlatitude cirrus",2014,"10.1002/2013JD020035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84900523423&doi=10.1002%2f2013JD020035&partnerID=40&md5=951c83dff93573fadc34d05e145894d4","In situ microphysical observations of midlatitude cirrus collected during the Department of Energy Small Particles in Cirrus (SPARTICUS) field campaign are combined with an atmospheric state classification for the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site to understand statistical relationships between cirrus microphysics and the large-scale meteorology. The atmospheric state classification is informed about the large-scale meteorology and state of cloudiness at the ARM SGP site by combining ECMWF ERA-Interim reanalysis data with 14 years of continuous observations from the millimeter-wavelength cloud radar. Almost half of the cirrus cloud occurrences in the vicinity of the ARM SGP site during SPARTICUS can be explained by three distinct synoptic conditions, namely, upper level ridges, midlatitude cyclones with frontal systems, and subtropical flows. Probability density functions (PDFs) of cirrus microphysical properties such as particle size distributions (PSDs), ice number concentrations, and ice water content (IWC) are examined and exhibit striking differences among the different synoptic regimes. Generally, narrower PSDs with lower IWC but higher ice number concentrations are found in cirrus sampled in upper level ridges, whereas cirrus sampled in subtropical flows, fronts, and aged anvils show broader PSDs with considerably lower ice number concentrations but higher IWC. Despite striking contrasts in the cirrus microphysics for different large-scale environments, the PDFs of vertical velocity are not different, suggesting that vertical velocity PDFs are a poor predictor for explaining the microphysical variability in cirrus. Instead, cirrus microphysical contrasts may be driven by differences in ice supersaturations or aerosols. © 2014. American Geophysical Union. All Rights Reserved."
"6506537159;35584010200;8247122100;","Thermodynamic and aerosol controls in southeast Pacific stratocumulus",2012,"10.1175/JAS-D-11-0165.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861463874&doi=10.1175%2fJAS-D-11-0165.1&partnerID=40&md5=05aeadcc894af354d693b906b903c98b","A near-large-eddy simulation approach with size-revolving (bin) microphysics is employed to evaluate the relative sensitivity of southeast Pacific marine boundary layer cloud properties to thermodynamic and aerosol parameters. Simulations are based on a heavily drizzling cloud system observed by the NOAA ship Ronald H. Brown during the Variability of theAmericanMonsoon Systems (VAMOS)Ocean-Cloud-Atmosphere-Land Study-Regional Experiment (VOCALS-Rex) field campaign.A suite of numerical experiments examines the sensitivity of drizzle to variations in boundary layer depth and cloud condensation nuclei (CCN) concentration in a manner consistent with the variability of those parameters observed during VOCALS-Rex. All four simulations produce cellular structures and turbulence characteristics of a circulation driven predominantly in a bottom-up fashion. The cloud and subcloud layers are coupled by strong convective updrafts that provide moisture to the cloud layer. Distributions of reflectivity calculated from model droplet spectra agree well with reflectivity distributions from the 5-cm-wavelength scanning radar aboard the ship, and the statistical behavior of cells over the course of the simulation is similar to that documented in previous studies of southeast Pacific stratocumulus. The simulations suggest that increased aerosol concentration delays the onset of drizzle, whereas changes in the boundary layer height are more important in modulating drizzle intensity. © 2012 American Meteorological Society."
"57212816521;7102101132;","Sheared deep vortical convection in pre-depression Hagupit during TCS08",2010,"10.1029/2009GL042313","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949800241&doi=10.1029%2f2009GL042313&partnerID=40&md5=7f7b4cd9cf52d3bc76606ac16385bd17","Airborne Doppler radar observations from the recent Tropical Cyclone Structure 2008 field campaign in the western North Pacific reveal the presence of deep, buoyant and vortical convective features within a vertically-sheared, westward-moving pre-depression disturbance that later developed into Typhoon Hagupit. On two consecutive days, the observations document tilted, vertically coherent precipitation, vorticity, and updraft structures in response to the complex shearing flows impinging on and occurring within the disturbance near 18 north latitude. The observations and analyses herein suggest that the low-level circulation of the pre-depression disturbance was enhanced by the coupling of the low-level vorticity and convergence in these deep convective structures on the meso-gamma scale, consistent with recent idealized studies using cloud-representing numerical weather prediction models. Further examination of these new observations is needed to quantify the relative role of these vortical convection features in the tropical cyclone spin up process. Copyright © 2010 by the American Geophysical Union."
"6602975095;7101956981;7003414581;7403361959;6701697023;7006634316;57200679067;21646972800;","An intercomparison of aerosol light extinction and 180° backscatter as derived using in situ instruments and Raman lidar during the INDOEX field campaign",2002,"10.1029/2000JD000035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042516928&doi=10.1029%2f2000JD000035&partnerID=40&md5=571688f42bc383ad3ee77f340228b8f9","Aircraft in situ and Raman lidar profiles of aerosol light extinction (σ<inf>ep</inf>) and 180° backscattering (β<inf>p</inf>) are compared for 6 days during the Indian Ocean Experiment (INDOEX). The measurements of σ<inf>ep</inf> and β<inf>p</inf> were made from the National Center for Atmospheric Research C-130 aircraft using two integrating nephelometers to measure light scattering and one Radiance Research Particle Soot Absorption Photometer to measure light absorption. Particulate 180° backscattering was measured in situ using a new instrument, the 180° backscatter nephelometer. The Institute for Tropospheric Research Raman lidar was located on the island of Hulule (4.18°N, 73.53°E), and all of the in situ profiles presented are from descents into the Hulule airport. Aerosol optical depth was also measured from Hulule using a Sun photometer, and these data are included in the intercomparison. On average, the lidar-derived values of σ<inf>ep</inf> and β<inf>p</inf> are ∼30% larger than the in situ-derived values to a 95% confidence interval. Possible reasons for the overall discrepancy are (1) a low bias in the in situ measurements because of losses in the C-130 Community Aerosol Inlet; (2) underestimation of the humidification effect on light extinction in the in situ measurements; (3) overestimation of σ<inf>ep</inf> and β<inf>p</inf> in the lidar because of subvisible cloud contamination; (4) errors in data processing that could be biasing either measurement, though the lidar retrievals are especially sensitive to this type of error. Temporal and spatial variability also appear to be the source of at least some of the discrepancy in two of the six cases, none of which are well collocated. Copyright 2002 by the American Geophysical Union."
"7003510880;56032594900;7201572145;57200967773;26422803600;55324559500;55747201700;56872745700;9233178200;57195348014;27667585700;57200504215;15827278200;6602497877;57219982231;6603423022;57194589938;55435417200;7801524854;35326039600;56522444900;6602999057;","An overview of the diurnal cycle of the atmospheric boundary layer during the West African monsoon season: Results from the 2016 observational campaign",2018,"10.5194/acp-18-2913-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042689151&doi=10.5194%2facp-18-2913-2018&partnerID=40&md5=e993616263c04c4f16009c69a5b71dfe","A ground-based field campaign was conducted in southern West Africa from mid-June to the end of July 2016 within the framework of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project. It aimed to provide a high-quality comprehensive data set for process studies, in particular of interactions between low-level clouds (LLCs) and boundary-layer conditions. In this region missing observations are still a major issue. During the campaign, extensive remote sensing and in situ measurements were conducted at three supersites: Kumasi (Ghana), Savè (Benin) and Ile-Ife (Nigeria). Daily radiosoundings were performed at 06:00 UTC, and 15 intensive observation periods (IOPs) were performed during which additional radiosondes were launched, and remotely piloted aerial systems were operated. Extended stratiform LLCs form frequently in southern West Africa during the nighttime and persist long into the following day. They affect the radiation budget and hence the evolution of the atmospheric boundary layer and regional climate. The relevant parameters and processes governing the formation and dissolution of the LLCs are still not fully understood. This paper gives an overview of the diurnal cycles of the energy-balance components, near-surface temperature, humidity, wind speed and direction as well as of the conditions (LLCs, low-level jet) in the boundary layer at the supersites and relates them to synoptic-scale conditions (monsoon layer, harmattan layer, African easterly jet, tropospheric stratification) in the DACCIWA operational area. The characteristics of LLCs vary considerably from day to day, including a few almost cloud-free nights. During cloudy nights we found large differences in the LLCs' formation and dissolution times as well as in the cloud-base height. The differences exist at individual sites and also between the sites. The synoptic conditions are characterized by a monsoon layer with south-westerly winds, on average about 1.9 km deep, and easterly winds above; the depth and strength of the monsoon flow show great day-to-day variability. Within the monsoon layer, a nocturnal low-level jet forms in approximately the same layer as the LLC. Its strength and duration is highly variable from night to night. This unique data set will allow us to test some new hypotheses about the processes involved in the development of LLCs and their interaction with the boundary layer and can also be used for model evaluation. © Author(s) 2018."
"55545906300;6602867567;6603350772;23768259900;26643081200;55465944900;","A combination of DISPATCH downscaling algorithm with CLASS land surface scheme for soil moisture estimation at fine scale during cloudy days",2016,"10.1016/j.rse.2016.06.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973659351&doi=10.1016%2fj.rse.2016.06.010&partnerID=40&md5=211f33066c6051afdb0ee3eeae6acc87","The main objective of this study is to propose and evaluate a new approach to overcome the major limitation of downscaling methods based on optical/thermal data, particularly the DISaggregation based on Physical And Theoretical scale Change (DISPATCH) algorithm. Data collected over an agricultural site located in Winnipeg (Manitoba, Canada) during the SMAP Validation Experiments 2012 (SMAPVEX12) field campaign were used. At this site, SMOS soil moisture estimates showed a relatively good correlation for both AM and PM overpasses (R ≥ 0.67), but with a significant underestimation (bias ≈ -0.10 m3/m3), when compared to ground data. SMOS soil moisture data also showed a significant sensitivity to rainfall events. The DISPATCH algorithm was used to downscale bias-corrected SMOS soil moisture data over the study area for the cloud-free days during SMAPVEX12. Compared to ground data, DISPATCH performed well, especially with the soil evaporative efficiency (SEE) linear model (R = 0.81, bias = -0.01 m3/m3, RMSE = 0.05 m3/m3), which slightly outperformed the SEE non-linear model (R = 0.72, bias = -0.01 m3/m3, RMSE = 0.06 m3/m3). For both models, the accuracy of the downscaling soil moisture is inversely proportional to the absolute value of soil moisture. For cloudy days, a new operational downscaling approach was proposed. It consists of combining the soil moisture simulations of the Canadian Land Surface Scheme (CLASS) with DISPATCH-downscaled soil moisture during cloud-free days in order to provide estimates of temporally continuous series of soil moisture at 1 km resolution. Compared to ground soil moisture data, the results indicated the high potential of our approach to retrieve soil moisture at 1 km resolution during cloudy days (R = 0.80, bias = -0.01 m3/m3, RMSE = 0.07 m3/m3). © 2016 Elsevier Inc."
"7003440089;6603553760;55993369600;16443893300;57210222492;6603745481;17346981400;37123320600;56400886500;56681868600;56400768700;7102317973;","Characterization of the boundary layer at Dome C (East Antarctica) during the OPALE summer campaign",2015,"10.5194/acp-15-6225-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84930938893&doi=10.5194%2facp-15-6225-2015&partnerID=40&md5=505a789cdc1f428b6c81bf2fb697a61c","Regional climate model MAR (Modèle Atmosphérique Régional) was run for the region of Dome C located on the East Antarctic plateau, during Antarctic summer 2011-2012, in order to refine our understanding of meteorological conditions during the OPALE tropospheric chemistry campaign. A very high vertical resolution is set up in the lower troposphere, with a grid spacing of roughly 2 m. Model output is compared with temperatures and winds observed near the surface and from a 45 m high tower as well as sodar and radiation data. MAR is generally in very good agreement with the observations, but sometimes underestimates cloud formation, leading to an underestimation of the simulated downward long-wave radiation. Absorbed short-wave radiation may also be slightly overestimated due to an underestimation of the snow albedo, and this influences the surface energy budget and atmospheric turbulence. Nevertheless, the model provides sufficiently reliable information about surface turbulent fluxes, vertical profiles of vertical diffusion coefficients and boundary layer height when discussing the representativeness of chemical measurements made nearby the ground surface during field campaigns conducted at Concordia station located at Dome C (3233 m above sea level). © Author(s) 2015."
"7101886364;6602137800;7003359002;57000710600;7401844779;35304081800;7006421484;7004174939;7404061081;36611965700;25648525300;","Comparison of MODIS 3 km and 10 km resolution aerosol optical depth retrievals over land with airborne sunphotometer measurements during ARCTAS summer 2008",2014,"10.5194/acp-14-2015-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84894483517&doi=10.5194%2facp-14-2015-2014&partnerID=40&md5=1a40d02d2f621744bf0f79a19798ea68","Airborne sunphotometer measurements acquired by the NASA Ames Airborne Tracking Sunphotometer (AATS-14) aboard the NASA P-3 research aircraft are used to evaluate dark-target over-land retrievals of extinction aerosol optical depth (AOD) from spatially and temporally near-coincident measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) during the summer 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. The new MODIS Collection 6 aerosol data set includes retrievals of AOD at both 10 km × 10 km and 3 km × 3 km (at nadir) resolution. In this paper we compare MODIS and AATS AOD at 553 nm in 58 10 km and 134 3 km retrieval grid cells. These AOD values were derived from data collected over Canada on four days during short time segments of five (four Aqua and one Terra) satellite overpasses of the P-3 during low-altitude P-3 flight tracks. Three of the five MODIS-AATS coincidence events were dominated by smoke: one included a P-3 transect of a well-defined smoke plume in clear sky, but two were confounded by the presence of scattered clouds above smoke. The clouds limited the number of MODIS retrievals available for comparison, and led to MODIS AOD retrievals that underestimated the corresponding AATS values. This happened because the MODIS aerosol cloud mask selectively removed 0.5 km pixels containing smoke and clouds before the aerosol retrieval. The other two coincidences (one Terra and one Aqua) occurred during one P-3 flight on the same day and in the same general area, in an atmosphere characterized by a relatively low AOD (< 0.3), spatially homogeneous regional haze from smoke outflow with no distinguishable plume. For the ensemble data set for MODIS AOD retrievals with the highest-quality flag, MODIS AOD agrees with AATS AOD within the expected MODIS over-land AOD uncertainty in 60% of the retrieval grid cells at 10 km resolution and 69% at 3 km resolution. These values improve to 65 % and 74%, respectively, when the cloud-affected case with the strongest plume is excluded. We find that the standard MODIS dark-target over-land retrieval algorithm fails to retrieve AOD for thick smoke, not only in cloud-contaminated regions but also in clear sky. We attribute this to deselection, by the cloud and/or bright surface masks, of 0.5 km resolution pixels that contain smoke. © 2014 Author (s)."
"56384704800;55717074000;56162305900;7006303509;23065650200;55463274000;35494005000;","Evaluating and constraining ice cloud parameterizations in CAM5 using aircraft measurements from the SPARTICUS campaign",2013,"10.5194/acp-13-4963-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896755723&doi=10.5194%2facp-13-4963-2013&partnerID=40&md5=bb0bbe5c474c01eee002b09a184fe2ef","This study uses aircraft measurements of relative humidity and ice crystal size distribution collected during the SPARTICUS (Small PARTicles In CirrUS) field campaign to evaluate and constrain ice cloud parameterizations in the Community Atmosphere Model version 5. About 200h of data were collected during the campaign between January and June 2010, providing the longest aircraft measurements available so far for cirrus clouds in the midlatitudes. The probability density function (PDF) of ice crystal number concentration (N i) derived from the high-frequency (1 Hz) measurements features a strong dependence on ambient temperature. As temperature decreases from -35 °C to -62 °C, the peak in the PDF shifts from 10-20 L-1 to 200-1000 L-1, while Ni shows a factor of 6-7 increase. Model simulations are performed with two different ice nucleation schemes for pure ice-phase clouds. One of the schemes can reproduce a clear increase of Ni with decreasing temperature by using either an observation-based ice nuclei spectrum or a classical-theory-based spectrum with a relatively low (5-10%) maximum freezing ratio for dust aerosols. The simulation with the other scheme, which assumes a high maximum freezing ratio (100%), shows much weaker temperature dependence of Ni. Simulations are also performed to test empirical parameters related to water vapor deposition and the autoconversion of ice crystals to snow. Results show that a value between 0.05 and 0.1 for the water vapor deposition coefficient, and 250 μm for the critical diameter that distinguishes ice crystals from snow, can produce good agreement between model simulation and the SPARTI-CUS measurements in terms of Ni and effective radius. The climate impact of perturbing these parameters is also discussed. © Author(s) 2013."
"36898773100;57213653167;16444265000;24458137900;10144486700;15127430500;55976582900;8937902100;7005423580;36898651700;8732198500;56179033200;16445063600;7005219614;","Distribution of hydrogen peroxide and formaldehyde over Central Europe during the HOOVER project",2011,"10.5194/acp-11-4391-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955915325&doi=10.5194%2facp-11-4391-2011&partnerID=40&md5=2bf4828619e79b22900fc1e6c8dc91de","In this study we report measurements of hydrogen peroxide (H2O2), methyl hydroperoxide* (MHP* as a proxy of MHP based on an unspecific measurement of total organic peroxides) and formaldehyde (HCHO) from the HOx OVer EuRope (HOOVER) project (HOx Combining double low line OH+HO2). HOOVER included two airborne field campaigns, in October 2006 and July 2007. Measurement flights were conducted from the base of operation Hohn (Germany, 54&deg; N, 9&deg; E) towards the Mediterranean and to the subpolar regions over Norway. We find negative concentration gradients with increasing latitude throughout the troposphere for H2O2 and CH3OOH*. In contrast, observed HCHO is almost homogeneously distributed over central and northern Europe and is elevated over the Mediterranean. In general, the measured gradients tend to be steepest entering the Mediterranean region, where we also find the highest abundances of the 3 species. Mixing ratios of these tracers generally decrease with altitude. H2O2 and CH3OOH* show maxima above the boundary layer at 2-5 km, being more distinct over southern than over northern Europe. We also present a comparison of our data with simulations by two global 3-D-models, MATCH-MPIC and EMAC, and with the box model CAABA. The models realistically represent altitude and latitude gradients for both HCHO and hydroperoxides (ROOH). In contrast, the models have problems reproducing the absolute mixing ratios, in particular of H2O2. Large uncertainties about retention coefficients and cloud microphysical parameters suggest that cloud scavenging might be a large source of error for the simulation of H2O2. A sensitivity study with EMAC shows a strong influence of cloud and precipitation scavenging on the budget of H2O2 as simulations improve significantly with this effect switched off. © 2011 Author(s)."
"7201966094;57203405965;25649028800;6603800142;23091000900;7101886364;6602137800;7401844779;","Aerosol spectral absorption in the Mexico City area: Results from airborne measurements during MILAGRO/INTEX B",2010,"10.5194/acp-10-6333-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954618529&doi=10.5194%2facp-10-6333-2010&partnerID=40&md5=69bcb0b81ae476ae33e7778ca319ec6f","This paper presents estimates of the spectral solar absorption due to atmospheric aerosols during the 2006 MILAGRO/INTEX-B (Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment) field campaign. The aerosol absorption was derived from measurements of the spectral solar radiation and the spectral aerosol optical depth made on the J31 aircraft flying over the Gulf of Mexico and over Mexico City. We present the spectral single scattering albedo (SSA) and aerosol absorption optical depth (AAOD) for two flights over the Gulf of Mexico and three flights over Mexico City for wavelengths from 350 to approximately 1650 nm. The spectral aerosol optical properties of each case are different and illustrate the variability of the aerosol optical properties in the Mexico City area. The results can be described in terms of three different wavelength regions: The 350-500 nm region where the aerosol absorption often falls off sharply presumably due to organic carbonaceous particles and windblown dust; the 500-1000 nm region where the decrease with wavelength is slower presumably due to black carbon; and the near infrared spectral region (1000 nm to 1650 nm) where it is difficult to obtain reliable results since the aerosol absorption is relatively small and the gas absorption dominates. However, there is an indication of a small and somewhat wavelength independent absorption in the region beyond 1000 nm. For one of the flights over the Gulf of Mexico near the coastline it appears that a cloud/fog formation and evaporation led to an increase of absorption possibly due to a water shell remaining on the particles after the cloud/fog had dissipated. For two of the Mexico City cases, the single scattering albedo is roughly constant between 350-500 nm consistent with other Mexico City results. In three of the cases a single absorption Angstrom exponent (AAE) fits the aerosol absorption optical depth over the entire wavelength range of 350 to 1650 nm relatively well (r2&gt; 0.86). © 2010 Author(s)."
"6506642126;","Ensemble-based sensitivity analysis applied to African easterly waves",2010,"10.1175/2009WAF2222255.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953594912&doi=10.1175%2f2009WAF2222255.1&partnerID=40&md5=c91d70de7839f2f068b3250efd68bd5e","An ensemble Kalman filter (EnKF) coupled to the Advanced Research version of the Weather Research and Forecasting (WRF) model is used to generate ensemble analyses and forecasts of a strong African easterly wave (AEW) during the African Monsoon Multidisciplinary Analysis field campaign. Ensemble sensitivity analysis is then used to evaluate the impacts of initial condition errors on AEW amplitude and position forecasts at two different initialization times. WRF forecasts initialized at 0000 UTC 8 September 2006, prior to the amplification of the AEW, are characterized by large variability in evolution as compared to forecasts initialized 48 h later when theAEWis within a denser observation network. Short-lead-time amplitude forecasts are most sensitive to the midtropospheric meridional winds, while at longer lead times, midtropospheric Θe errors have equal or larger impacts. For AEW longitude forecasts, the largest sensitivities are associated with the Θe downstream of the AEW and, to a lesser extent, the meridional winds. Ensemble predictions of how initial condition errors impact the AEW amplitude and position compare qualitatively well with perturbed integrations of the WRF model. Much of the precipitation associated with the AEW is generated by the Kain-Fritsch cumulus parameterization, thus the initial-condition sensitivities are also computed for ensemble forecasts that employ the Betts-Miller-Janjić and Grell cumulus parameterization schemes, and for a high-resolution nested domain with explicit convection, but with the same initial conditions. While the 12-h AEW amplitude forecast is characterized by consistent initial-condition sensitivity among the different schemes, there is greater variability among methods beyond 24 h. In contrast, the AEW longitude forecast is sensitive to the downstream thermodynamic profile with all cumulus schemes. © 2010 American Meteorological Society."
"7004057920;8343401100;6603712566;56036132800;57201726470;","A high-resolution oxygen A-band and water vapor band spectrometer",2004,"10.1029/2003jd003540","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2642528808&doi=10.1029%2f2003jd003540&partnerID=40&md5=f66c51636114e296cba34d8e08c9584d","A prototype high-resolution oxygen A-band and water vapor band spectrometer (HAWS) and new theoretical framework have been developed and demonstrated to study the applicability of photon path length statistics in the remote sensing of clouds, aerosols, and water vapor, particularly in addressing current challenges such as the detection of thin layers of clouds and aerosols especially over surfaces with high albedo, reducing retrieval errors due to the presence of non-spherical particles, and enhancing the vertical resolution of retrieved atmospheric constituents. This work also provides a basis for the application of path length distribution in the development and validation of radiative transfer parameterizations that account for the effects of cloud inhomogeneity. The HAWS successfully achieves an out-of-band rejection of better than 10-5, a resolution of better than 0.5 cm-1, and high signal-to-noise ratio, which are crucial to retrieval of atmospheric information through high-resolution spectrometry in the A-band and water vapor band. A field campaign was conducted to demonstrate the capabilities of HAWS and the new retrieval algorithm at the cloud and radiation testbed at ARM SGP site in Oklahoma, where a comprehensive set of radiometric, passive, and active sensors provide continuous and concurrent measurements of clouds, aerosols, water vapor, and other atmospheric properties. Results show that in the A-band thick and multiple layer clouds significantly enhance the mean and variance of the photon path length distribution, thin cirrus condition produce relatively small mean distribution and variance, and mean path lengths comp arable to or smaller than the solar airmass were associated with clear sky cases at large solar zenith angles. The mean path length and variance in the water vapor band differs from that in the A-band due to the spatial inhomogeneity of water vapor amounts, particularly in association with cloud layers. Copyright 2004 by the American Geophysical Union."
"10640183500;7202315227;7004898341;","Field experimental investigations on the Fe(II)- and Fe(III)-content in cloudwater samples",2001,"10.1023/A:1010684628804","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034869252&doi=10.1023%2fA%3a1010684628804&partnerID=40&md5=9d8378ff9a2446ba5479909042d34fc7","The Fe(II)/Fe(III)-partition in cloudwater samples collected during two field campaigns is evaluated. It turned out that the simultaneous occurrence of complexing and reducing substances in the atmosphere and the cloud processing increase the solubility of iron compounds present in aerosol particles. A correlation between the concentration of iron(II) in the liquid phase and the intensity of the solar irradiation was observed for most of the cloudwater samples. This could be due to the fact that both the photochemical reduction of the iron(III) complexes and the photochemical reductive dissolution of iron(III)(hydr)oxides are depending on the pH-value. Iron(II) seems to be oxidised back to iron(III) preferably by hydrogen peroxide during the night. Positive correlations were received e.g. between the concentration of dissolved iron and the concentration of oxalate and between the percentage of iron(III) and the concentration of hydrogen peroxide. A negative correlation was found e.g. between the concentration of dissolved iron and the pH-value. The uncertainty of the whole process of sampling and analysis was investigated and the conformity of the results was satisfying considering the sometimes difficult conditions during a field campaign."
"12800966700;57202425542;8657166100;7003535385;35572096100;7004242319;24465126800;36106049900;6506454031;6701754792;23017945100;36573180000;56358933300;","Ice crystal sizes in high ice water content clouds. Part II: Statistics of mass diameter percentiles in tropical convection observed during the HAIC/HIWC project",2017,"10.1175/JTECH-D-15-0246.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009252503&doi=10.1175%2fJTECH-D-15-0246.1&partnerID=40&md5=d5883acac09fed9fe4ec296c3c0399f6","High ice water content (IWC) regions in mesoscale convective systems (MCSs) are a potential threat to commercial aviation, as they are suspected to cause in-service engine power-loss events and air data probe malfunctions. To investigate this, the high-altitude ice crystals (HAIC)/high ice water content (HIWC) projects set up a first field campaign in Darwin (Australia) in 2014. The airborne instrumentation was selected to provide the most accurate measurements of both the bulk total water content (TWC), using a specially developed isokinetic evaporator, and the individual ice crystals properties, using particle imaging probes. This study focuses on determining the size ranges of ice crystals responsible for the mass in high IWC regions, defined here as cloud regions with IWC greater than 1.5 g m-3. It is shown that for high IWC areas in most of the encountered MCSs, median mass diameters (MMDs) of ice crystals range from 250 to 500 μm and decrease with increasing TWC and decreasing temperature. At the same time, the mass contribution of the smallest crystals (below 100 μm) remains generally low (below 15%). In contrast, data from two flight missions in a long-lasting quasi-stationary tropical storm reveal that high IWC values can also be associated with MMDs in the range 400-800 μm and peak values of up to 2 mm. Ice crystal images suggest a major growth contribution by vapor deposition (columns, capped columns) even for such larger MMD values. © 2017 American Meteorological Society."
"7201832531;16745169900;56879816400;6507871748;8598729400;35510702700;7004436916;7003461830;55173498100;55032226400;56971031200;6505827596;37122211300;26434039800;7005734412;7005206400;57204253860;6701836226;57193214099;53980757300;","Linking meteorology, turbulence, and air chemistry in the amazon rain forest",2016,"10.1175/BAMS-D-15-00152.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011568933&doi=10.1175%2fBAMS-D-15-00152.1&partnerID=40&md5=5b4eed0216445dbe475c6e0243b42f9c","A field campaign reveals that the Amazon rain forest produces enough chemical species to undergo oxidation and generate aerosols, which can activate into cloud condensation nuclei and potentially influence cloud formation. © 2016 American Meteorological Society."
"22635042200;7202240406;15761381100;7409078608;57102115200;","Grey Tienshan Urumqi Glacier No.1 and light-absorbing impurities",2016,"10.1007/s11356-016-6182-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957605436&doi=10.1007%2fs11356-016-6182-7&partnerID=40&md5=ccd6251a855999913274faabf6121225","The Tienshan Urumqi Glacier No.1 (TUG1) usually shows “grey” surfaces in summers. Besides known regional warming, what should be responsible for largely reducing its surface albedo and making it look “grey”? A field campaign was conducted on the TUG1 on a selected cloud-free day of 2013 after a snow fall at night. Fresh and aged snow samples were collected in the field, and snow densities, grain sizes, and spectral reflectances were measured. Light-absorbing impurities (LAIs) including black carbon (BC) and dust, and number concentrations and sizes of the insoluble particles (IPs) in the samples were measured in the laboratory. High temperatures in summer probably enhanced the snow ageing. During the snow ageing process, the snow density varied from 243 to 458 kg m−3, associated with the snow grain size varying from 290 to 2500 μm. The concentrations of LAIs in aged snow were significantly higher than those in fresh snow. Dust and BC varied from 16 ppm and 25 ppb in fresh snow to 1507 ppm and 1738 ppb in aged snow, respectively. Large albedo difference between the fresh and aged snow suggests a consequent forcing of 180 W m−2. Simulations under scenarios show that snow ageing, BC, and dust were responsible for 44, 25, and 7 % of the albedo reduction in the accumulation zone, respectively. © 2016, The Author(s)."
"35113492400;56611366900;24765069600;55272477500;","Scale dependence of entrainment-mixing mechanisms in cumulus clouds",2014,"10.1002/2014JD022265","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921340617&doi=10.1002%2f2014JD022265&partnerID=40&md5=5bb128304ddf8a158009cde776b6613f","This work empirically examines the dependence of entrainment-mixing mechanisms on the averaging scale in cumulus clouds using in situ aircraft observations during the Routine Atmospheric Radiation Measurement Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign. A new measure of homogeneous mixing degree is defined that can encompass all types of mixing mechanisms. Analysis of the dependence of the homogenous mixing degree on the averaging scale shows that, on average, the homogenous mixing degree decreases with increasing averaging scales, suggesting that apparent mixing mechanisms gradually approach from homogeneous mixing to extreme inhomogeneous mixing with increasing scales. The scale dependence can be well quantified by an exponential function, providing first attempt at developing a scale-dependent parameterization for the entrainment-mixing mechanism. The influences of three factors on the scale dependence are further examined: droplet-free filament properties (size and fraction), microphysical properties (mean volume radius and liquid water content of cloud droplet size distributions adjacent to droplet-free filaments), and relative humidity of entrained dry air. It is found that the decreasing rate of homogeneous mixing degree with increasing averaging scales becomes larger with larger droplet-free filament size and fraction, larger mean volume radius and liquid water content, or higher relative humidity. The results underscore the necessity and possibility of considering averaging scale in representation of entrainment-mixing processes in atmospheric models. © 2014. American Geophysical Union. All Rights Reserved."
"7102423967;8629713500;7401796996;","Aerosol properties and their influences on marine boundary layer cloud condensation nuclei at the ARM mobile facility over the Azores",2014,"10.1002/2013JD021288","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84900556177&doi=10.1002%2f2013JD021288&partnerID=40&md5=688678fce980a5fc183e81d0bdfb87ba","A multiplatform data set fromthe Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (MBL) Graciosa, Azores, 2009-2010 field campaign was used to investigate how continental aerosols can influenceMBL cloud condensation nuclei (CCN) number concentration (NCCN). The seasonal variations of aerosol properties have shown that the winter and early spring months had the highest mean surface wind speed (&gt; 5ms-1) and greatest contribution of sea salt to aerosol optical depth (AOD), while continental fine mode aerosols were the main contributors to AOD during the warm season months (May-September). Five aerosol events consisting of mineral dust, pollution, biomass smoke, and volcanic ash particles were selected as case studies using Atmospheric Radiation Measurement (ARM) mobile facility measurements. The aerosols in Case I were found to primarily consist of coarsemode, Saharan mineral dust. For Case II, the aerosols were also coarse mode but consisted of volcanic ash. Case III had fine mode biomass smoke and pollution aerosol influences while Cases IV and V consisted ofmixtures of North American pollution and Saharan dust that was advected by an extratropical cyclone to the Azores. Cases I, IV, and V exhibited weak correlations between aerosol loading and NCCN due to mineral dust influences, while Cases II and III had a strong relationship with NCCN likely due to the sulfate content in the volcanic ash and pollution particles. The permanent Eastern North Atlantic ARM facility over the Azores will aid in a future long-term study of aerosol effects on NCCN. © 2014. American Geophysical Union. All Rights Reserved."
"26028515700;7003865921;7005729142;7202016984;7404514776;55545601500;7004678728;","Cloud ice water content retrieved from the CALIOP space-based lidar",2012,"10.1029/2011GL050545","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863231968&doi=10.1029%2f2011GL050545&partnerID=40&md5=25bd8cd4b64bdb6589063e93fe26906d","Ice water content (IWC) profiles are derived from retrievals of optical extinction from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite lidar, using a parameterization derived from particle probe measurements acquired during several aircraft field campaigns. With more than five years of data now available, CALIOP IWC is well suited for characterization of the climate-sensitive upper troposphere/lower stratosphere where reliable global IWC measurements are needed to reduce climate model uncertainty. We describe CALIOP IWC and compare it with global satellite-based and regional airborne IWC measurements made during August 2007. IWC distributions in a convective cloud sampled during the Tropical Clouds, Chemistry, Composition and Climate experiment show temperature-dependent differences between in situ measured IWC, IWC retrieved from CloudSat and CALIOP, and IWC parameterized from the airborne Cloud Physics Lidar (CPL) 532 nm volume extinction coefficients. At temperatures above-50°C the CALIOP IWC retrieval indicates less cloud ice than the other instruments, due to signal attenuation and screening for horizontally-oriented ice crystals. Above 12 km where temperatures drop below-50°C CALIOP compares well with in situ IWC measurements. In situ measurements are limited above 12 km, and more cold-temperature comparisons are needed. Global zonal in-cloud IWC averages at altitudes above 9 km show that CloudSat IWC is roughly an order of magnitude higher than CALIOP IWC, consistent with a higher detection threshold. When averaged to the vertical resolution characteristic of Microwave Limb Sounder (MLS), global zonal averages of CALIOP and MLS IWC were found to agree to about 50%."
"6701404949;7003372165;7202035883;35305673400;8217208200;7005382046;","VOCALS-CUpEx: The Chilean Upwelling Experiment",2011,"10.5194/acp-11-2015-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79952326434&doi=10.5194%2facp-11-2015-2011&partnerID=40&md5=c6880b3b71f556a739f2cb4dd32334e9","The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) was a major field experiment conducted in spring of 2008 off southern Peru and northern Chile, aimed at better understanding the coupled climate systems of the southeast Pacific. Because of logistical constrains, the coastal area around 30° S was not sampled during VOCALS-REx. This area not only marks the poleward edge of the subtropical stratocumulus cloud regime (thus acting as a source of transient disturbances) but is also one of the most active upwelling centers and source of surface ocean kinetic energy along the Chilean coast. To fill such an observational gap, a small, brief, but highly focused field experiment was conducted in late spring 2009 in the near-shore region around 30° S. The Chilean Upwelling Experiment (CUpEx) was endorsed by VOCALS as a regional component. CUpEx included long-term monitoring, an intensive twoweek field campaign and off-shore research flights. Our goal was to obtain an atmospheric/oceanic dataset with enough temporal and spatial coverage to be able to document (a) the mean diurnal cycles of the lower-troposphere and upper-ocean in a region of complex topography and coastline geometry, and (b) the ocean-atmosphere response to the rapid changes in coastal winds from strong, upwelling-favorable equatorward flow (southerly winds) to downwelling-favorable poleward flow (northerly winds). In this paper we describe the measurement platforms and sampling strategy, and provide an observational overview, highlighting some key mean-state and transient features. © 2011 Author(s)."
"33067634600;6701596624;57193882808;","Effective radius and droplet spectral width from in-situ aircraft observations in trade-wind cumuli during RICO",2009,"10.1029/2009GL038257","https://www.scopus.com/inward/record.uri?eid=2-s2.0-68949091775&doi=10.1029%2f2009GL038257&partnerID=40&md5=48536875ec7f5ea67c439d5b05b8c714","This paper presents statistics of cloud microphysical properties of shallow tropical cumuli observed by a research aircraft during RICO field campaign. Cloud properties are derived from 10 Hz (about 10 m spatial distance) Fast-FSSP data in four different flights. The motivation comes from similar analyses of either aircraft data from stratocumulus clouds or remote-sensing data of tropical cumuli. In the lowest few hundred meters, the standard deviation of the droplet size distribution σr and the relative dispersion, the ratio of σr and the mean radius, are similar to stratocumulus clouds, but they are significantly larger in the upper half of the cloud field depth. The frequency distribution of the effective radius is significantly narrower than in the remote-sensing observations in the middle and upper third of the cloud field. These results can be used in parameterizations and validations of cloud microphysics in numerical models of various complexity. Copyright 2009 by the American Geophysical Union."
"6701412834;14819069200;9233163800;6603468918;7003813649;6602751071;7103161954;35413839400;9845365600;8361905700;","Technical note: First spectral measurement of the Earth's upwelling emission using an uncooled wideband Fourier transform spectrometer",2006,"10.5194/acp-6-5025-2006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33750547386&doi=10.5194%2facp-6-5025-2006&partnerID=40&md5=f120c80d7390013afaba883ab9b8910a","The first spectral measurement of Earth's emitted radiation to space in the wideband range from 100 to 1400 cm-1 with 0.5 cm-1 spectral resolution is presented. The measurement was performed from a stratospheric balloon in tropical region using a Fourier transform spectrometer, during a field campaign held in Brazil in June 2005. The instrument, which has uncooled components including the detector module, is a prototype developed as part of the study for the REFIR (Radiation Explorer in the Far InfraRed) space mission. This paper shows the results of the field campaign with particular attention to the measurement capabilities of the prototype. The results are compared with measurements taken by IASI-balloon (Infrared Atmospheric Sounding Interferometer - Balloon version), aboard the same platform, and with forward model estimations. The infrared signature of clouds is observed in the measurements."
"7410041005;7003283811;7501447027;7005729142;","Retrieving optically thick ice cloud microphysical properties by using airborne dual-wavelength radar measurements",2005,"10.1029/2005JD005969","https://www.scopus.com/inward/record.uri?eid=2-s2.0-28044437342&doi=10.1029%2f2005JD005969&partnerID=40&md5=cbd6d36dc7c19b80af88a5f17125d357","An-algorithm to retrieve optically thick ice cloud microphysical property profiles is developed by using the GSFC 9.6 GHz ER-2 Doppler Radar (EDOP) and the 94 GHz Cloud Radar System (CRS) measurements aboard the high-altitude ER-2 aircraft. In situ size distribution and total water content data from the CRYSTAL-FACE field campaign are used for the algorithm development. To reduce uncertainty in calculated radar reflectivity factors (Ze) at these wavelengths, coincident radar measurements and size distribution data are used to guide the selection of mass-length relationships and to deal with the density and nonspherical effects of ice crystals on the Ze calculations. The algorithm is able to retrieve microphysical property profiles of optically thick ice clouds, such as deep convective and anvil clouds, which are very challenging for single-wavelength radar and lidar. Examples of retrieved microphysical properties for deep convective clouds are presented, which show that EDOP and CRS measurements provide rich information to study cloud structure and evolution. Good agreement between IWPs derived from an independent submillimeter-wave radiometer, CoSSIR, and dual-wavelength radar measurements indicates accuracy of the IWC retrieved from the dual-wavelength radar algorithm. Copyright 2005 by the American Geophysical Union."
"8084443000;7004015298;7003658685;24465126800;7102317973;6603553760;","Contribution of gaseous and particulate species to droplet solute composition at the Puy de Dôme, France",2003,"10.5194/acp-3-1509-2003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-32844473593&doi=10.5194%2facp-3-1509-2003&partnerID=40&md5=478799b33975ba097846dd8fd7fec96e","Chemical reactions of dissolved gases in the liquid phase play a key role in atmospheric processes both in the formation of secondary atmospheric compounds and their wet removal rate but also in the regulation of the oxidizing capacity of the troposphere. The behavior of gaseous species and their chemical transformation in clouds are difficult to observe experimentally given the complex nature of clouds. During a winter field campaign at the summit of the Puy de Dôme (central France, 1465ma.s.l), we have deployed an experimental set-up to provide a quantification of phase partitioning of both organic (CH3COOH, HCOOH, H2C2O4) and inorganic (NH3, HNO3, SO2, HCl) species in clouds. We found that nitric and hydrochloric acids can be considered close to Henry's law equilibrium, within analytical uncertainty and instrumental errors. On another hand, for NH3 and carboxylic acids, dissolution of material from the gas phase is kinetically limited and never reaches the equilibrium predicted by thermodynamics, resulting in significant sub-saturation of the liquid phase. On the contrary, SIV is supersaturated in the liquid phase, in addition to the presence of significant aerosol-derived S VI transferred through nucleation scavenging. Upon droplet evaporation, a significant part of most species, including SIV, tends to efficiently return back into the gas phase. Overall, gas contribution to the droplet solute concentration ranges from at least 48.5 to 98% depending on the chemical species. This is particularly important considering that aerosol scavenging efficiencies are often calculated assuming a negligible gas-phase contribution to the solute concentration. Our study emphasizes the need to account for the in-cloud interaction between particles and gases to provide an adequate modeling of multiphase chemistry systems and its impact on the atmospheric aerosol and gas phases. © 2003 European Geosciences Union."
"6603543777;7006450978;56261420900;7005051644;","Lightning evolution related to radar-derived microphysics in the 21 July 1998 EULINOX supercell storm",2001,"10.1016/S0169-8095(00)00085-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034456226&doi=10.1016%2fS0169-8095%2800%2900085-5&partnerID=40&md5=24d29db99d874ff0fe72bf0411019ec7","Results of a combined analysis of data from a C-band polarimetric Doppler radar and a 3D VHF interferometric lightning mapping system, as obtained during the European Lightning Nitrogen Oxides project (EULINOX) field campaign, are presented. For 21 July 1998, the lightning data from a supercell thunderstorm weakly indicate a tendency for a bi-level vertical distribution of lightning VHF emissions around the - 15°C and - 30°C temperature levels. Also, in some parts of the clouds, evidence is found for the presence of a lower positive charge center near the freezing level. However, where strong vertical motions prevail, VHF emissions are not organized in horizontal layers but in oblique or vertical regions. Correlation of VHF signals with radar quantities shows that in the growing storm, peak VHF activity is low and related to reflectivity factors around 30 dBZ, while after the mature stage, the peak VHF activity is about three times larger. The highest density of VHF signals is now found near reflectivity factors of 45 dBZ. A polarimetric hydrometeor classification indicates that during storm development, most lightning activity occurs where graupel and, secondarily, snow and small dry hail are present. In the decaying phase of the supercell hailstorm, however, most lightning VHF emissions stem from the region with hail and heavy rain. Furthermore, while the VHF signal frequency per cubic kilometer in the graupel and rain regions remains nearly constant throughout the supercell life cycle, the signal frequency in the hail region rises during storm decay. © 2001 Elsevier Science B.V. All rights reserved."
"36916954400;7401553123;","Does a lightning channel show a fractal?",2000,"10.1016/S0306-2619(00)00011-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033704337&doi=10.1016%2fS0306-2619%2800%2900011-8&partnerID=40&md5=13368dbe418d012e12efd59c3f2c7f65","Forecasting the striking point of a lightning flash is important for the reduction of lightning hazards. Field campaigns have been conducted, and the features of leader progression have been investigated for this final goal. Both streak and still camera observations are used, because we can obtain useful information on the leader progression manner and its velocity. A radio interferometer is another useful instrument, by which, we can capture a lightning channel image from its initiation inside the thundercloud to the attachment process to the ground. Though many laborious investigations have been performed and various results have been presented, the exact forecasting of a striking point still remains difficult. To overcome this, numerical simulations of a stepped leader near the ground surface have been carried out using the leader progression model, which has been improved by using the fractal mathematical concept. In other words, the proposed scheme in this paper is a probabilistic procedure. The finite-difference approach is applied to the two-dimensional Poisson's equation to calculate the electric field produced by the charge distribution in a thundercloud. The stepped leaders, which are initiated at the lower part of the cloud and usually proceed towards the ground, are simulated to study the theoretical stepped leader progression. The zig-zags and branches of a lightning channel can also be simulated. © 2000 Elsevier Science Ltd."
"35551238800;6602999057;56522444900;35736729500;7201572145;57200494488;7006837187;15827278200;57217801354;6603932982;7003510880;23995619200;6701679993;56032594900;7006424590;56187256200;8657166100;26422803600;9233178200;57195348014;27667585700;56183181400;57200504215;7005941217;55683878900;7006377579;7004393835;8412336900;6603180620;56495287900;57200502078;26659013400;8760535800;6603423022;57195673296;9536598800;25958833500;25228665000;55226243300;14058796400;55435417200;56195655500;55783064400;7004944088;16217869500;","The dynamics⇓aerosol⇓chemistry⇓cloud interactions in west Africa field campaign",2018,"10.1175/BAMS-D-16-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040906806&doi=10.1175%2fBAMS-D-16-0&partnerID=40&md5=e441bc5038658694ac00769e3b77c6b5","Unprecedented ground-based and aircraft measurements in southern West Africa characterize atmospheric composition and dynamics, low-level cloud properties, the diurnal cycle, and air pollution impacts on health. © 2018 American Meteorological Society."
"7102132806;56726831900;56269827600;23011735800;26867472700;56260422800;7006861480;7006377579;55454856700;8622374000;7006235542;56648175200;57205787051;56124038800;9044746800;21933618400;35740180800;7103197731;25627961800;57195257572;56648032900;56284582200;36504116600;6602999057;36941730100;57208217651;57189089842;32367837300;7004860305;11839146600;7003733477;56647469500;57203492395;7005446873;6701905330;7202129754;55226243300;34868683400;7202619752;14025125600;36790738100;56647587400;7003986828;7102366101;13007754100;25523100000;","Cloud banding and winds in intense European cyclones: Results from the DIAMET project",2015,"10.1175/BAMS-D-13-00238.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84929458857&doi=10.1175%2fBAMS-D-13-00238.1&partnerID=40&md5=1ea29e2a8441128a7c6c099c0a1fff54","The Diabatic Influences on Mesoscale Structures in Extratropical Storms (DIAMET) project aims to improve forecasts of high-impact weather in extratropical cyclones through field measurements, high-resolution numerical modeling, and improved design of ensemble forecasting and data assimilation systems. This article introduces DIAMET and presents some of the first results. Four field campaigns were conducted by the project, one of which, in late 2011, coincided with an exceptionally stormy period marked by an unusually strong, zonal North Atlantic jet stream and a succession of severe windstorms in northwest Europe. As a result, December 2011 had the highest monthly North Atlantic Oscillation index (2.52) of any December in the last 60 years. Detailed observations of several of these storms were gathered using the U.K.'s BAe 146 research aircraft and extensive ground-based measurements. As an example of the results obtained during the campaign, observations are presented of Extratropical Cyclone Friedhelm on 8 December 2011, when surface winds with gusts exceeding 30 m s-1 crossed central Scotland, leading to widespread disruption to transportation and electricity supply. Friedhelm deepened 44 hPa in 24 h and developed a pronounced bent-back front wrapping around the storm center. The strongest winds at 850 hPa and the surface occurred in the southern quadrant of the storm, and detailed measurements showed these to be most intense in clear air between bands of showers. High-resolution ensemble forecasts from the Met Office showed similar features, with the strongest winds aligned in linear swaths between the bands, suggesting that there is potential for improved skill in forecasts of damaging winds. ©2015 American Meteorological Society."
"8708213500;7201504886;24336460200;","Wind shear and buoyancy reversal at the top of stratocumulus",2014,"10.1175/JAS-D-13-0189.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896760563&doi=10.1175%2fJAS-D-13-0189.1&partnerID=40&md5=fb505edffae70209ab610be4998a6a4e","A numerical experiment is designed to study the interaction at the stratocumulus top between a mean vertical shear and the buoyancy reversal due to evaporative cooling, without radiative cooling. Direct numerical simulation is used to eliminate the uncertainty introduced by turbulence models. It is found that the enhancement by shear-induced mixing of the turbulence caused by buoyancy reversal can render buoyancy reversal comparable to other forcing mechanisms. However, it is also found that (i) the velocity jump across the capping inversion δu needs to be relatively large and values of about 1 ms -1 that are typically associated with the convective motions inside the boundary layer are generally too small and (ii) there is no indication of cloud-top entrainment instability. To obtain these results, parameterizations of the mean entrainment velocity and the relevant time scales are derived from the study of the cloud-top vertical structure. Two overlapping layers can be identified: a background shear layer with a thickness (1/3)(δu)-2/δb, where δb is the buoyancy increment across the capping inversion and a turbulence layer dominated by free convection inside the cloud and by shear production inside the relatively thin overlap region. As turbulence intensifies, the turbulence layer encroaches into the background shear layer and defines thereby the entrainment velocity. Particularized to the first research flight of the Second Dynamics andChemistry of theMarine Stratocumulus (DYCOMS II) field campaign, the analysis predicts an entrainment velocity of about 3 mms -1 after 5-10 min-a velocity comparable to the measurements and thus indicative of the relevance of mean shear in that case. © 2014 American Meteorological Society."
"24482254700;7004459129;6602390932;55944619500;56217116900;55056533200;57213253047;8525148200;24482221200;25643556600;8732198500;55502994400;","Tropospheric BrO column densities in the Arctic derived from satellite: Retrieval and comparison to ground-based measurements",2012,"10.5194/amt-5-2779-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84869450842&doi=10.5194%2famt-5-2779-2012&partnerID=40&md5=95e5516f6eacbc3016133617b4d5e969","During polar spring, halogen radicals like bromine monoxide (BrO) play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2). Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The presented algorithm furthermore allows to estimate a realistic measurement error of the tropospheric BrO column. The sensitivity of each satellite pixel to BrO in the boundary layer is quantified using the measured UV radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement with ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary layer meteorology influences the vertical distribution. © 2012 Author(s)."
"7406200372;55796629114;36119737000;55719328100;55487543500;7201791739;7406686011;55716266100;7005219614;","The IPAC-NC field campaign: A pollution and oxidization pool in the lower atmosphere over Huabei, China",2012,"10.5194/acp-12-3883-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860645080&doi=10.5194%2facp-12-3883-2012&partnerID=40&md5=44026a8f70225ec1244a1b2d4c8ca73d","In the past decades, regional air pollution characterized by photochemical smog and grey haze-fog has become a severe environmental problem in China. To investigate this, a field measurement campaign was performed in the Huabei region, located between 32-42° N latitude in eastern China, during the period 2 April-16 May 2006 as part of the project ""Influence of Pollution on Aerosols and Cloud Microphysics in North China"" (IPAC-NC). It appeared that strong pollution emissions from urban and industrial centers tend to accumulate in the lower atmosphere over the central area of Huabei. We observed widespread, very high SO2 mixing ratios, about 20-40 ppbv at 0.5-1.5 km altitude and 10-30 ppbv at 1.5-3.0 km altitude. Average CO mixing ratios were 0.65-0.7 ppmv at 0.5-1.5 km altitude, and very high CO around 1 ppmv was observed during some flights, and even higher levels at the surface. We find the high pollution concentrations to be associated with enhanced levels of OH and HO 2 radicals, calculated with a chemical box model constrained by the measurements. In the upper part of the boundary layer and in the lower free troposphere, high CO and SO 2 compete with relatively less NO 2 in reacting with OH, being efficiently recycled through HO 2, preventing a net loss of HO x radicals. In addition to reactive hydrocarbons and CO, the oxidation of SO 2 causes significant ozone production over Huabei (up to ∼13% or 2.0 ppbv h -1 at 0.8 km altitude). Our results indicate that the lower atmosphere over Huabei is not only strongly polluted but also acts as an oxidation pool, with pollutants undergoing very active photochemistry over this part of China. © 2012 Author(s)."
"7406215388;7404187535;7004884101;7004091067;","Vertical structure of precipitation and related microphysics observed by NOAA profilers and TRMM during NAME 2004",2007,"10.1175/JCLI4102.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249722738&doi=10.1175%2fJCLI4102.1&partnerID=40&md5=43ec9bbad2ff86ef198206edf1b270bb","In support of the 2004 North American Monsoon Experiment (NAME) field campaign, NOAA established and maintained a field site about 100 km north of Mazatlán, Mexico, consisting of wind profilers, precipitation profilers, surface upward-downward-looking radiometers, and a 10-m meteorological tower to observe the environment within the North American monsoon. Three objectives of this NOAA project are discussed in this paper: 1) to observe the vertical structure of precipitating cloud systems as they passed over the NOAA profiler site, 2) to estimate the vertical air motion and the raindrop size distribution from near the surface to just below the melting layer, and 3) to better understand the microphysical processes associated with stratiform, rain containing well-defined radar bright bands. To provide a climatological context for the profiler observations at the field site, the profiler reflectivity distributions were compared with Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) reflectivity distributions from the 2004 season over the NAME domain as well as from the 1998-2005 seasons. This analysis places the NAME 2004 observations into the context of other monsoon seasons. It also provides a basis for evaluating the representativeness of the structure of the precipitation systems sampled at this location. The number of rain events observed by the TRMM PR is dependent on geography; the land region, which includes portions of the Sierra Madre Occidental, has more events than the coast and gulf regions. Conversely, from this study it is found that the frequencies of occurrence of stratiform rain and reflectivity profiles with radar bright bands are mostly independent of region. The analysis also revealed that the reflectivity distribution at each height has more year-to-year variability than region-to-region variability. These findings suggest that in cases with a well-defined bright band, the vertical profile of the reflectivity relative to the height of the bright band is similar over the gulf, coast, and land regions. © 2007 American Meteorological Society."
"14020751800;57202531041;55339298600;","Determination of three-dimensional cloud structures from high-resolution radiance data",2006,"10.1029/2005JD006062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745228451&doi=10.1029%2f2005JD006062&partnerID=40&md5=a9945b37a38bf6c0f133b602b240d0c7","The three-dimensional structure and the inhomogeneity of clouds pose a field of challenges. The characterization of their spatial structure, their microphysical properties, and their variability is difficult. This kind of knowledge is crucial to any investigation on the impact of clouds on the radiation budget or on the reliability of cloud remote sensing data. In this article the characteristics of radiation transport in inhomogeneous clouds are studied using three-dimensional (3-D) simulations of radiative transport and the independent pixel approximation (IPA). The opposing effects of radiative smoothing and sharpening due to horizontal photon transport are examined in terms of the Green's function, which describes the interrelation of the radiance fields calculated using IPA and 3-D radiative transport. On the basis of these considerations a novel method was developed for the retrieval of realistic 3-D stratocumulus structures from high-spatial-resolution radiance fields observed by a compact airborne spectrographic imager (CASI, 15 m resolution). An initial distribution of liquid water content and effective droplet size retrieved using the IPA assumption and an adiabatic microphysical model is iteratively adjusted with the objective of matching the observation by the 3-D forward radiative transfer simulation for the derived cloud. For the iterative adjustment an approximate Green's function is utilized to remove 3-D effects from the observation. The performance of the method is characterized by application to a known cloud structure and by comparison of the derived cloud properties to in situ data from various field campaigns. The method provides the ideal basis for our studies on the remote sensing of inhomogeneous clouds. Copyright 2006 by the American Geophysical Union."
"7003726500;","An approach to the estimation of surface net radiation in mountain areas using remote sensing and digital terrain data",1995,"10.1007/BF00865507","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029435281&doi=10.1007%2fBF00865507&partnerID=40&md5=536a0d5d652e1c09cb5e7d4c716e9270","An approach is proposed to estimate the net radiation load at the surface in mountain areas. The components of the radiation balance are derived using a radiative transfer model combined with remotely sensed and digital terrain data. Integrated shortwave (0.28-6.00 μm) and longwave irradiances (3.00-100.00 μm) are computed using a modified version of the Practical Improved Flux Method (PIFM) of Zdunkowski et al. (1982) which makes use of digital topographic data in order to account for slope, aspect, and shading effects. Surface albedo and thermal exitance estimates are obtained using Landsat Thematic Mapper (TM) and digital terrain data combined with the LOWTRAN 7 atmospheric model (Kneizys et al., 1988). LOWTRAN 7 is utilized together with a set of terrain modeling programs to compute direct and diffuse sky irradiance for selected TM bands, and to remove atmospheric effects within the visible, near-infrared, mid-infrared, and thermal infrared bands of Landsat TM. Model testing in the Colorado alpine show a generally good correspondence between estimated values and field measurements obtained over comparable tundra surfaces during several field campaigns. The method is finally used to produce 1) maps of the components of the radiation balance at the time of Landsat TM overflight and 2) maps of daily totals of shortwave irradiance and net shortwave radiation on a typical summer day in the Colorado Rocky Mountains (i.e. including cloud cover effects). The results indicate that the proposed approach is particularly suitable for obtaining estimates of net radiation at the surface from the toposcale to the regional scale. © 1995 Springer-Verlag."
"57188702132;57188696698;57193916172;16549790100;35771409400;55857180100;57189212954;6602559573;7801401670;24366038500;7003414581;8980175400;7006058570;17341189400;7003323678;6603497648;","Ice nucleating particles over the Eastern Mediterranean measured by unmanned aircraft systems",2017,"10.5194/acp-17-4817-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017503287&doi=10.5194%2facp-17-4817-2017&partnerID=40&md5=0bb9e08a88a7bb698cb660a193ac8c50","During an intensive field campaign on aerosol, clouds, and ice nucleation in the Eastern Mediterranean in April 2016, we measured the abundance of ice nucleating particles (INPs) in the lower troposphere from unmanned aircraft systems (UASs). Aerosol samples were collected by miniaturized electrostatic precipitators onboard the UASs at altitudes up to 2.5 km. The number of INPs in these samples, which are active in the deposition and condensation modes at temperatures from -20 to -30 °C, were analyzed immediately after collection on site using the ice nucleus counter FRIDGE (FRankfurt Ice nucleation Deposition freezinG Experiment). During the 1-month campaign, we encountered a series of Saharan dust plumes that traveled at several kilometers' altitude. Here we present INP data from 42 individual flights, together with aerosol number concentrations, observations of lidar backscattering, dust concentrations derived by the dust transport model DREAM (Dust Regional Atmospheric Model), and results from scanning electron microscopy. The effect of the dust plumes is reflected by the coincidence of INPs with the particulate matter (PM), the lidar signal, and the predicted dust mass of the model. This suggests that mineral dust or a constituent related to dust was a major contributor to the ice nucleating properties of the aerosol. Peak concentrations of above 100 INPs std L-1 were measured at -30 °C. The INP concentration in elevated plumes was on average a factor of 10 higher than at ground level. Since desert dust is transported for long distances over wide areas of the globe predominantly at several kilometers' altitude, we conclude that INP measurements at ground level may be of limited significance for the situation at the level of cloud formation. © Author(s) 2017."
"56000281400;7005051510;6602601702;22940839800;56709556500;6505837381;24553828600;7006788343;6602529898;57034923400;","An Overview of the MATERHORN Fog Project: Observations and Predictability",2016,"10.1007/s00024-016-1374-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986538346&doi=10.1007%2fs00024-016-1374-0&partnerID=40&md5=11cc45f1ba67fcb481ecbaed530bb5a1","A field campaign design to study fog processes in complex terrain was a component of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program. The experiment was conducted in the Wasatch Mountains during January 5–February 15, 2015. Fog and in particular, Ice fog (IF), defined as fog composed of only ice crystals, was studied during a part of the campaign, and this component of the program was dubbed MATERHORN-Fog. Ice fog often occurs in mountainous regions due do rapid cooling, such as radiative cooling, advective cooling, and cooling associated with mountain circulations (e.g., slope and valley winds). A variety of major instrument platforms were deployed, which included meteorological towers, a SODAR, a LiDAR, ceilometers, and a tethersonde profiler. In addition, in situ measurements took place at several locations surrounding Salt Lake City and Heber City. During the campaign, ice fog occurred at temperatures below −5 °C down to −13 °C and lasted for several hours until radiative heating became significant. The visibility (Vis) during ice fog events ranged from 100 m up to 10 km. At the Heber City site an array of sensors for measuring microphysical, radiative, and dynamical characteristics of IF events were deployed. Some local effects such as upslope advection were observed to affect the IF conditions. As expected during these events, ice water content (IWC) varied from 0.01 up to 0.2 g m−3, with radiative cooling fluxes as strong as 200 W m−2; turbulent heat and moisture fluxes were significantly lower during fog events than those of fog dissipation. At times, the measured ice crystal number concentration was as high as 100 cm−3 during periods of saturation with respect to ice. Ni was not a constant as usually assumed in forecasting simulations, but rather changed with increasing IWC. Measurement based statistics suggested that the occurrence of IF events in the region was up to 30 % during the study period in the winter of 2015. Temperature profiles suggested that an inversion layer contributed significantly to IF formation at Heber. Ice fog forecasts via Weather Research and Forecasting (WRF) model indicated the limitations of IF predictability. Results suggest that IF predictions need to be improved based on ice microphysical parameterizations and ice nucleation processes. © 2016, Her Majesty the Queen in Right of Canada as represented by Environment Canada."
"36243762400;7801684147;36458602300;6603431534;19337612500;","Fingerprints of a riming event on cloud radar Doppler spectra: Observations and modeling",2016,"10.5194/acp-16-2997-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960969559&doi=10.5194%2facp-16-2997-2016&partnerID=40&md5=fc82a951a30ee0e41545a78f4dd5d7e4","Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW) layer. The focus is on the ""golden sample"" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations."
"36054921000;7102567936;56919125400;","Modeling the MJO in a cloud-resolving model with parameterized large-scale dynamics: Vertical structure, radiation, and horizontal advection of dry air",2016,"10.1002/2015MS000529","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956867509&doi=10.1002%2f2015MS000529&partnerID=40&md5=c4b3d3e83f3049be80d83f1fedb7875a","Two Madden-Julian Oscillation (MJO) events, observed during October and November 2011 in the equatorial Indian Ocean during the DYNAMO field campaign, are simulated in a limited-area cloud-resolving model using parameterized large-scale dynamics. Three parameterizations of large-scale dynamics - the conventional weak temperature gradient (WTG) approximation, vertical mode-based spectral WTG (SWTG), and damped gravity wave coupling (DGW) - are employed. A number of changes to the implementation of the large-scale parameterizations, as well as the model itself, are made and lead to improvements in the results. Simulations using all three methods, with imposed time-dependent radiation and horizontal moisture advection, capture the time variations in precipitation associated with the two MJO events well. The three methods produce significant differences in the large-scale vertical motion profile, however. WTG produces the most top-heavy profile, while DGW's is less so, and SWTG produces a profile between the two, and in better agreement with observations. Numerical experiments without horizontal advection of moisture suggest that that process significantly reduces the precipitation and suppresses the top-heaviness of large-scale vertical motion during the MJO active phases. Experiments in which a temporally constant radiative heating profile is used indicate that radiative feedbacks significantly amplify the MJO. Experiments in which interactive radiation is used produce agreement with observations that is much better than that achieved in previous work, though not as good as that with imposed time-varying radiative heating. Our results highlight the importance of both horizontal advection of moisture and radiative feedbacks to the dynamics of the MJO. © 2015. The Authors."
"56810883100;7402934750;6603196991;57195215491;","Ground-based temperature and humidity profiling using spectral infrared and microwave observations. Part II: Actual retrieval performance in clear-sky and cloudy conditions",2015,"10.1175/JAMC-D-15-0005.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949009203&doi=10.1175%2fJAMC-D-15-0005.1&partnerID=40&md5=b159f9dc4ecb52b6c6774774de73a822","Although current upper-air observing systems provide an impressive array of observations,many are deficient in observing the temporal evolution of the boundary layer thermodynamic profile. Ground-based remote sensing instruments such as the multichannel microwave radiometer (MWR) and Atmospheric Emitted Radiance Interferometer (AERI) are able to provide profiles of temperature and water vapor through the boundary layer at 5-min resolution or better. Previous work compared these instruments through optimal-estimation retrievals on simulated clear-sky spectra to evaluate the retrieval accuracy and information content of each instrument. In this study, this method is duplicated using real observations from collocated MWR and AERI instruments from a field campaign in southwestern Germany. When compared with radiosondes, this study confirms the previous results thatAERI retrievals aremore accurate thanMWRretrievals in clear-sky and below-cloud-base profiling. These results demonstrate that theAERI has nearly 2 times as much information as the MWR. © 2015 American Meteorological Society."
"7003842561;36076994600;56611366900;6603079013;6701562043;7005263785;56660388600;","Cloud microphysical relationships and their implication on entrainment and mixing mechanism for the stratocumulus clouds measured during the VOCALS project",2015,"10.1002/2014JD022802","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84932194472&doi=10.1002%2f2014JD022802&partnerID=40&md5=653d9cbc3fb84feb9a3df54849455d22","Cloud microphysical data obtained from G-1 aircraft flights over the southeastern Pacific during the Variability of the American Monsoon Systems Ocean-Cloud-Atmosphere-Land Study Regional Experiment field campaign were analyzed for evidence of entrainment mixing of dry air from above cloud top. Mixing diagram analysis was made for the horizontal flight data recorded at 1Hz and 40 Hz. The dominant observed feature, a positive relationship between cloud droplet mean volume (V) and liquid water content (L), suggested occurrence of homogeneous mixing. On the other hand, estimation of the relevant scale parameters (i.e., transition length scale and transition scale number) consistently indicated inhomogeneous mixing. Importantly, the flight altitudes of the measurements were significantly below cloud top. We speculate that mixing of the entrained air near the cloud top may have indeed been inhomogeneous; but due to vertical circulation mixing, the correlation between V and L became positive at the measurement altitudes in midlevel of clouds, because during their descent, cloud droplets evaporate, faster in more diluted cloud parcels, leading to a positive correlation between V and L regardless of the mixing mechanism near the cloud top. © 2015. American Geophysical Union. All rights reserved."
"6506328135;34881780600;37099564300;36059595100;7402480218;57211676851;7403077486;","Evaluation of convection-permitting model simulations of cloud populations associated with the madden-julian oscillation using data collected during the AMIE/DYNAMO field campaign",2014,"10.1002/2014JD022143","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84913534082&doi=10.1002%2f2014JD022143&partnerID=40&md5=a9a1a4bdda97a77e5221e57493d31d3c","Regional convection-permitting model simulations of cloud populations observed during the 2011 Atmospheric Radiation Measurement (ARM) Madden-Julian Oscillation Investigation Experiment/Dynamics of the Madden-Julian Oscillation Experiment (AMIE/DYNAMO) field campaign are evaluated against ground-based radar and ship-based observations. Sensitivity of model simulated reflectivity, surface rain rate, and cold pool statistics to variations of raindrop breakup/self-collection parameters in four state-of-the-art two-moment bulk microphysics schemes in the Weather Research and Forecasting (WRF) model is examined. The model simulations generally overestimate reflectivity from large and deep convective cells, and underestimate stratiform rain and the frequency of cold pools. In the sensitivity experiments, introduction of more aggressive raindrop breakup or decreasing the self-collection efficiency increases the cold pool occurrence frequency in all of the simulations, and slightly reduces the reflectivity and precipitation statistics bias in some schemes but has little effect on the overall mean surface precipitation. Both the radar observations and model simulations of cloud populations show an approximate power law relationship between convective echo-top height and equivalent convective cell radius. © 2014. American Geophysical Union. All Rights Reserved."
"55220380900;55494241100;7004934146;55540474000;55990027000;55990095000;55990071100;55989898800;8985856500;6603386686;7006316225;","Does canopy wetness matter? Evapotranspiration from a subtropical montane cloud forest in Taiwan",2014,"10.1002/hyp.9662","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84891745420&doi=10.1002%2fhyp.9662&partnerID=40&md5=1397d958fb8e00560255de6367f4f777","Evapotranspiration (ET) and canopy wetness were measured over a 2-year intensive field campaign at the Chi-Lan Mountain cloud forest site in Taiwan. Eddy covariance and sap flow methods were applied to measure ET and tree sap flow of the endemic yellow cypress (Chamaecyparis obtusa var. formosana). ET was 553mmyr-1 over the study period with an annual rainfall and fog deposition of 4893 and 288mmyr-1, respectively. The duration of canopy wetness exceeded actual fog or rain events (mostly in the afternoon), and the intercepted water was evaporated later in the following dry morning. The cumulative wet duration accounted for 52% of time over the study period, which was longer than the duration of rainfall and fog altogether (41%). As it adapted to the extremely moist environment, the yellow cypress behaved in a wet-enhanced/dry-reduced water use strategy and was sensitive to short periods of dry atmosphere with high evaporation potential. During dry days, the sap flow rate rose quickly after dawn and led to conservative water use through midday and the afternoon. During periodically wet days, the canopy was mostly wetted in the morning, and the interception evaporation contributed largely to the morning ET. The initiation of morning sap flow was postponed 1-3h, and the sap flow rate tended to peak later at midday. The midday canopy conductance was higher in the periodically wet days (10.6mms-1) as compared with 7.6mms-1 in the dry days. Consequently, the dry-reduced water use strategy led to much lower annual ET with respect to the available energy (~46%) and high precipitation input (~11%). The moist-adapted ecohydrology we report reveals the vulnerability of montane cloud forests to prolonged fog-free periods. More research is urgently needed to better understand the resilience of these ecosystems and formulate adaptive management plans. © 2012 John Wiley &amp; Sons, Ltd."
"7403364008;25647334300;25953950400;7005968859;","The role of the particle size distribution in assessing aerosol composition effects on simulated droplet activation",2010,"10.5194/acp-10-5435-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953839816&doi=10.5194%2facp-10-5435-2010&partnerID=40&md5=d727493f6d4145f23660295d2c9bcde6","Variations in the chemical composition of atmospheric aerosols alter their hygroscopicity and can lead to changes in the cloud-active fraction of the aerosols, or cloud condensation nuclei (CCN) number concentration. To investigate the importance of this effect under different atmospheric conditions, cloud droplet formation was simulated with a Lagrangian parcel model. Initial values of updraft speed and temperature were systematically varied along with aerosol number concentration, size and hygroscopicity (represented by the hygroscopicity parameter, κ). A previous study classifies the sensitivity of CCN activity to compositional changes based on the supersaturation reached in the parcel model. We found that these classifications could not be generalized to a range of aerosol size distribution median radii. Instead, variations in sensitivity with size depend on the location of the dry critical radius for droplet activation relative to the size distribution median radius. The parcel model output was used to construct droplet activation lookup tables based on κ that were implemented in the Regional Atmospheric Modeling System (RAMS) microphysical scheme. As a first application of this system, aerosol hygroscopicity and size were varied in a series of RAMS mesoscale simulations designed to investigate the sensitivity of a mixed-phase orographic cloud case to the parameter variations. Observations from a recent field campaign in northwestern Colorado provided the basis for the aerosol field initializations. Model results show moderate sensitivity in the distribution of total case precipitation to extreme changes in κ, and minimal sensitivity to observed changes in estimated κ. The impact of varying aerosol hygroscopicity diminished with increasing median radius, as expected from the parcel model results. The conclusions drawn from these simulations could simplify similar research in other cloud regimes by defining the need, or lack of need, for detailed knowledge of aerosol composition. © 2010 Author(s)."
"7103213900;24830922400;7005742394;6508104909;24462634500;","Investigation of droplet size distributions and drizzle formation using a new trajectory ensemble model. Part I: Model description and first results in a nonmixing limit",2008,"10.1175/2007JAS2486.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-52049110329&doi=10.1175%2f2007JAS2486.1&partnerID=40&md5=7d3f4c7eb92cc64de38ef0c239ee5ef9","A novel trajectory ensemble model of a stratocumulus cloud is described. In this model, the boundary layer (BL) is fully covered by a great number of Lagrangian air parcels that during their motion can contain either wet aerosols or aerosols and droplets. The diffusion growth of aerosols and droplets, as well as drop collisions, is accurately described in each parcel. Droplet sedimentation is taken into account, which allows simulation of precipitation formation. The Lagrangian parcels are advected by the velocity field generated by the turbulent-like flow model obeying turbulent correlation laws. The output of the numerical model includes droplet and aerosol size distributions and their moments, such as droplet concentration, droplet spectrum width, cloud water content, drizzle content, radar reflectivity, etc., calculated in each parcel. Horizontally averaged values are calculated as well. Stratocumulus clouds observed during two research flights (RF01 and RF07) in the Second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS II) field campaign are simulated. A good agreement between the dynamical and microphysical structures simulated by the model with observations is obtained even in the nonmixing limit. A crucial role of sedimentation for the creation of a realistic cloud microphysical structure is demonstrated. In sensitivity studies, the statistical stability of the model is analyzed. Applications of the model for the investigation of droplet size distribution and drizzle formation are discussed, as is the possible utilization of the model for remote sensing applications. © 2008 American Meteorological Society."
"22982059600;22979686100;12242009800;13406668600;6701842515;56613109400;56613126000;55682736300;9846688600;23048728700;13407563600;7003323678;55973913400;7006434689;55999273500;55730602600;56612704000;55984419100;55857180100;","Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques",2015,"10.5194/acp-15-4161-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928814782&doi=10.5194%2facp-15-4161-2015&partnerID=40&md5=d7e55cd13d985b1a6b68bf5b9ba285d8","In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20-70 %) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCHCIN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200-400 nm in geometric diameter. In a few cases, a second supermicron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the sub-micrometer range. Silicates and Ca-rich particles were mainly found with diameters above 1 μm (using ISI and FINCH), in contrast to the Ice-CVI which also sampled many submicron particles of both groups. Due to changing meteorological conditions, the INP/IPR composition was highly variable if different samples were compared. Thus, the observed discrepancies between the different separation techniques may partly result from the non-parallel sampling. The differences of the particle group relative number abundance as well as the mixing state of INP/IPR clearly demonstrate the need of further studies to better understand the influence of the separation techniques on the INP/IPR chemical composition. Also, it must be concluded that the abundance of contamination artifacts in the separated INP and IPR is generally large and should be corrected for, emphasizing the need for the accompanying chemical measurements. Thus, further work is needed to allow for routine operation of the three separation techniques investigated. © Author(s) 2015. CC Attribution 3.0 License."
"55958422800;57203348817;23009343400;","Wind speed control of tropical orographic convection",2014,"10.1175/JAS-D-13-0399.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84903904782&doi=10.1175%2fJAS-D-13-0399.1&partnerID=40&md5=762a34bcf0f931c81da8d42df97561e9","This study compares observations from the Dominica Experiment (DOMEX) field campaign with 3D and 2DWeatherResearch and ForecastingModel (WRF) simulations to understand flow ambient upstreamwind speed controls the transition from thermally to mechanically forced moist orographic convection. The environment is a conditionally unstable, tropical atmosphere with shalflow trade wind cumulus clouds. Three flow indices are defined to quantify the convective transition: horizontal divergence aloft, cloud location, and island surface temperature. As wind speed increases, horizontal airflow divergence from plume detrainment above the mountain changes to convergence associated with plunging flow, convective clouds relocate from the leeward to the windward side of the mountain as mechanically triggered convection takes over, and the daytime mountaintop temperature decreases because of increased ventilation and cloud shading. Possible mechanisms by which wind speed controls island precipitation are also discussed. The result is a clearer understanding of orographic convection in the tropics. © 2014 American Meteorological Society."
"7201587909;7403577184;36988140900;7202772927;7005742394;7006957668;7006874359;7005729142;6701653010;","Numerical analysis using WRF-SBM for the cloud microphysical structures in the C3VP field campaign: Impacts of supercooled droplets and resultant riming on snow microphysics",2012,"10.1029/2012JD018101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84871393326&doi=10.1029%2f2012JD018101&partnerID=40&md5=aefa81314e8310ff0548aebedd884a9b","Two distinct snowfall events are observed over the region near the Great Lakes during 19-23 January 2007 under the intensive measurement campaign of the Canadian CloudSat/CALIPSO validation project (C3VP). These events are numerically investigated using the Weather Research and Forecasting model coupled with a spectral bin microphysics (WRF-SBM) scheme that allows a smooth calculation of riming process by predicting the rimed mass fraction on snow aggregates. The fundamental structures of the observed two snowfall systems are distinctly characterized by a localized intense lake-effect snowstorm in one case and a widely distributed moderate snowfall by the synoptic-scale system in another case. Furthermore, the observed microphysical structures are distinguished by differences in bulk density of solid-phase particles, which are probably linked to the presence or absence of supercooled droplets. The WRF-SBM coupled with Goddard Satellite Data Simulator Unit (G-SDSU) has successfully simulated these distinctive structures in the three-dimensional weather prediction run with a horizontal resolution of 1km. In particular, riming on snow aggregates by supercooled droplets is considered to be of importance in reproducing the specialized microphysical structures in the case studies. Additional sensitivity tests for the lake-effect snowstorm case are conducted utilizing different planetary boundary layer (PBL) models or the same SBM but without the riming process. The PBL process has a large impact on determining the cloud microphysical structure of the lake-effect snowstorm as well as the surface precipitation pattern, whereas the riming process has little influence on the surface precipitation because of the small height of the system. © 2012. American Geophysical Union. All Rights Reserved."
"8503380500;7103185017;8503380800;6508304347;7004870145;6507174567;7003283897;7003626419;7004607037;6701773543;7401604360;6701925357;7004005379;8953514400;15848759600;57201720473;7403221533;16444236100;","Altitude effect in UV radiation during the Evaluation of the Effects of Elevation and Aerosols on the Ultraviolet Radiation 2002 (VELETA-2002) field campaign",2008,"10.1029/2007JD009742","https://www.scopus.com/inward/record.uri?eid=2-s2.0-59749091022&doi=10.1029%2f2007JD009742&partnerID=40&md5=b2a8a8f64483a630f0f580769c65b8b5","The Evaluation of the Effects of Elevation and Aerosols on the Ultraviolet Radiation 2002 (VELETA-2002) field campaign was designed to study the influence of aerosols and altitude on solar UV irradiance. The altitude effect (AE) was evaluated for UV irradiance under cloudless conditions by taking spectral and broadband measurements in SE Spain in the summer of 2002 at three nearby sites located at different heights (680 m, 2200 m, and 3398 m). A spectral radiative transfer model (Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART)) was also applied, mainly to evaluate the tropospheric ozone impact on AE. Results are related to the optical properties and air mass origin of the aerosols as determined by back-trajectory analysis. During the 1-week observing period of the campaign, there were two main synoptic situations with different air masses (polar maritime and tropical continental air mass associated with a Saharan dust event). The AE showed a high dependency on wavelength, solar zenith angle, and aerosols, although the growth of the mixing layer during the day also caused substantial AE variability. Saharan dust caused an increase in AE, especially in the UVB region and in the erythemal irradiance. In the UVA (320-400 nm) band the AE ranged 6-8% km-1 at noon, while for the UVB (280-320 nm) band it reached 7-11% km-1. The AE for erythemally weighted irradiance ranged from 11 to 14% km-1 between the lowest and highest stations when it was calculated from spectral measurements. Copyright 2008 by the American Geophysical Union."
"6604099174;24281186100;6602840804;55999772700;7403221533;","Influence of aerosol particles from biomass burning on cloud microphysical properties and radiative forcing",2006,"10.1016/j.atmosres.2005.10.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749134850&doi=10.1016%2fj.atmosres.2005.10.010&partnerID=40&md5=5216c3d5989d5c5cb149b9051dde7ebe","Aerosol from biomass burning has been shown to strongly modify cloud microphysical properties and cloud lifetime through the so-called ""indirect effect."" However, in the case of a lack of wet scavenging, it stays suspended for days to weeks and can be transported to considerable distances within an elevated layer above low-level cloud tops with minimal aerosol-cloud interactions. The observations carried out during the Southern African Regional Science Initiative (SAFARI) 2000 dry season field campaign often revealed the presence of an elevated biomass-burning aerosol layer above a semi-permanent stratiform cloud deck off the southern African coasts. MODerate-resolution Imaging Spectroradiometer (MODIS) cloud products were used to investigate the existence of an aerosol indirect effect on convective clouds. Results are presented documenting cloud effective radius and cloud radiative forcing variations due to the presence of the aerosol during the development of convective clouds. Radiative transfer simulations in the visible (0.8 μm, VIS) and near-infrared (1.6, 2.1 and 3.7 μm, NIR) wavelengths were instrumental in establishing the extent of the influence of a biomass-burning aerosol layer overlying a water cloud sheet on the MODIS satellite retrieval of cloud parameters, in particular the effective radius and the optical thickness. The radiative transfer simulations suggest that the presence of the aerosol induces a significant underestimation of the cloud optical thickness, whereas an underestimation of the retrieved effective radius is more pronounced in the retrieval that makes use of the 1.6 μm waveband than the 2.1 and 3.7 μm wavebands. The MODIS cloud products of 3 days of the SAFARI 2000 campaign were analyzed to determine whether the aerosol induced biases evidenced by the simulations also affect the operational cloud property retrieval. Cloud parameters, in particular the effective radius, are usually employed as indicators of the occurrence of aerosol-cloud interaction according to the ""indirect effect."" However, these results highlight some of the difficulties associated with satellite retrievals of cloud properties and show the importance of an accurate sighting of the cloud and aerosol layer top and bottom heights in order to prevent erroneous detections of indirect effects. © 2006 Elsevier B.V. All rights reserved."
"56196145800;6701313597;7102862273;7004692414;7102490158;55633197600;7003383481;6603457933;7003726515;","Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area",2004,"10.1111/j.1600-0889.2004.00128.x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-9444252812&doi=10.1111%2fj.1600-0889.2004.00128.x&partnerID=40&md5=713f383dad32ab5d9f948128f3d224da","Atmospheric aerosols play an important role in global climate change, directly through radiative forcing and indirectly through their effect on cloud properties. Numerous measurements have been performed in the last three decades in order to characterize polar aerosols. Information about aerosol characteristics is needed to calculate induced changes in the Earth's heat balance. However, this forcing is highly variable in space and time. Accurate quantification of forcing by aerosols will require combined efforts, assimilating information from different sources such as satellite, aircraft and surface-based observations. Adding to the complexity of the problem is that the measurements themselves are often not directly comparable as they vary in spatial/temporal resolution and in the basic properties of the aerosol that they measure. Therefore it is desirable to close the gap between the differences in temporal and spatial resolution and coverage among the observational approaches. In order to keep the entire information content and to treat aerosol variability in a consistent and manageable way an approach has to be achieved which enables one to combine these data. This study presents one possibility for linking together a complex Arctic aerosol data set in terms of parameters, timescale and place of measurement as well as meteorological parameters. A cluster analysis was applied as a pattern recognition technique. The data set is classified in clusters and expressed in terms of mean staristical values, which represent the entire database and its variation. For this study, different time-series of microphysical, optical and chemical aerosol parameters as well as meteorological parameters were analysed. The database was obtained during an extensive aerosol measurement campaign, the ASTAR 2000 (Arctic Study of Tropospheric Aerosol and Radiation) field campaign, with coordinated simultaneous ground-based and airborne measurements in the vicinity of Spitsbergen (Svalbard). Furthermore, long-term measurements at two ground-based sites situated at different altitudes were incorporated into the analysis. The approach presented in this study allows the necessary linking of routine long-term measurements with short-term extensive observations. It also involves integration of intermittent vertical aerosol profile measurements. This is useful for many applications, especially in climate research where the required data coverage is large. Copyright © Blackwell Munksguard 2004."
"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."
"57197197616;9537062600;15823214600;25821662300;23991021100;56912918900;7102930120;","Interannual surface evolution of an Antarctic blue-ice moraine using multi-temporal DEMs",2016,"10.5194/esurf-4-515-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977147479&doi=10.5194%2fesurf-4-515-2016&partnerID=40&md5=823b70db015ac13326919d21908c48e4","Multi-temporal and fine-resolution topographic data products are increasingly used to quantify surface elevation change in glacial environments. In this study, we employ 3-D digital elevation model (DEM) differencing to quantify the topographic evolution of a blue-ice moraine complex in front of Patriot Hills, Heritage Range, Antarctica. Terrestrial laser scanning (TLS) was used to acquire multiple topographic datasets of the moraine surface at the beginning and end of the austral summer season in 2012/2013 and during a resurvey field campaign in 2014. A complementary topographic dataset was acquired at the end of season 1 through the application of structure from motion with multi-view stereo (SfM-MVS) photogrammetry to a set of aerial photographs acquired from an unmanned aerial vehicle (UAV). Three-dimensional cloud-to-cloud differencing was undertaken using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm. DEM differencing revealed net uplift and lateral movement of the moraine crests within season 1 (mean uplift ∼ 0.10 m) and surface lowering of a similar magnitude in some inter-moraine depressions and close to the current ice margin, although we are unable to validate the latter. Our results indicate net uplift across the site between seasons 1 and 2 (mean 0.07 m). This research demonstrates that it is possible to detect dynamic surface topographical change across glacial moraines over short (annual to intra-annual) timescales through the acquisition and differencing of fine-resolution topographic datasets. Such data offer new opportunities to understand the process linkages between surface ablation, ice flow and debris supply within moraine ice. © 2016 Author(s)."
"35203939400;22633429500;57189051559;55807774100;36887737900;6701806265;","3-D water vapor field in the atmospheric boundary layer observed with scanning differential absorption lidar",2016,"10.5194/amt-9-1701-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964931494&doi=10.5194%2famt-9-1701-2016&partnerID=40&md5=c64e5ed730a63eccc800164157cf56b6","High-resolution three-dimensional (3-D) water vapor data of the atmospheric boundary layer (ABL) are required to improve our understanding of land-atmosphere exchange processes. For this purpose, the scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) was developed as well as new analysis tools and visualization methods. The instrument determines 3-D fields of the atmospheric water vapor number density with a temporal resolution of a few seconds and a spatial resolution of up to a few tens of meters. We present three case studies from two field campaigns. In spring 2013, the UHOH DIAL was operated within the scope of the HD(CP)2 Observational Prototype Experiment (HOPE) in western Germany. HD(CP)2 stands for High Definition of Clouds and Precipitation for advancing Climate Prediction and is a German research initiative. Range-height indicator (RHI) scans of the UHOH DIAL show the water vapor heterogeneity within a range of a few kilometers up to an altitude of 2 km and its impact on the formation of clouds at the top of the ABL. The uncertainty of the measured data was assessed for the first time by extending a technique to scanning data, which was formerly applied to vertical time series. Typically, the accuracy of the DIAL measurements is between 0.5 and 0.8 g m-3 (or &lt; 6 %) within the ABL even during daytime. This allows for performing a RHI scan from the surface to an elevation angle of 90° within 10 min. In summer 2014, the UHOH DIAL participated in the Surface Atmosphere Boundary Layer Exchange (SABLE) campaign in southwestern Germany. Conical volume scans were made which reveal multiple water vapor layers in three dimensions. Differences in their heights in different directions can be attributed to different surface elevation. With low-elevation scans in the surface layer, the humidity profiles and gradients can be related to different land cover such as maize, grassland, and forest as well as different surface layer stabilities. © Author(s) 2016."
"36459641300;7404570418;","Comparison of valid ocean observations between MODIS terra and aqua over the global oceans",2016,"10.1109/TGRS.2015.2483500","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946762732&doi=10.1109%2fTGRS.2015.2483500&partnerID=40&md5=2846f0bfdc95112fcf211d381443d032","Ocean color satellite missions to measure the biophysical and geochemical properties of the surface ocean need to consider not only the spectral and spatial requirements of the sensors but also the satellite overpass time to maximize valid observations. The valid observations are impacted not only by cloud cover but also by other perturbations such as sun glint and stray light. Using Level-3 global composites of three ocean products (chlorophyll a or Chl-a, normalized florescence line height or nFLH, and sea surface temperature or SST), the daily percentage valid observations (DPVOs) over the global oceans were calculated, from which the differences between MODIS Aqua (afternoon pass) and MODIS Terra (morning pass) have been analyzed. For all three products, Aqua shows more valid observations than Terra over the Southern Ocean, the ocean near Peru and Chile, and the ocean around Angola and Namibia, with relatively >30% more valid observations in boreal winter months due to lower cloud coverage in the afternoon. In contrast, more than 20% of valid Chl-a and nFLH observations are obtained by Terra in the North Indian Ocean, and 10%-30% more valid observations by Terra are also found for the Equatorial Pacific and Atlantic oceans. These can be possibly linked to the lower presence of sun glint for Terra. Compared with Chl-a and nFLH, SST retrievals are more tolerant to sun glint and other perturbation factors, leading to much higher DPVOs. The implications of these findings to future satellite mission design and field campaigns are also discussed. © 1980-2012 IEEE."
"40461229800;26639062900;7404187535;7006029393;7004091067;7006783796;7005773698;","Impact of interannual variations in sources of insoluble aerosol species on orographic precipitation over California's central Sierra Nevada",2015,"10.5194/acp-15-6535-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84934908847&doi=10.5194%2facp-15-6535-2015&partnerID=40&md5=0d314cfd1d4a2e5afa5845e270a9cefa","Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater field campaign (2009-2011), the variability and associated impacts of different aerosol sources on precipitation were investigated in the California Sierra Nevada using an aerosol time-of-flight mass spectrometer for precipitation chemistry, S-band profiling radar for precipitation classification, remote sensing measurements of cloud properties, and surface meteorological measurements. The composition of insoluble residues in precipitation samples collected at a surface site contained mostly local biomass burning and long-range-transported dust and biological particles (2009), local sources of biomass burning and pollution (2010), and long-range transport (2011). Although differences in the sources of insoluble residues were observed from year to year, the most consistent source of dust and biological residues were associated with storms consisting of deep convective cloud systems with significant quantities of precipitation initiated in the ice phase. Further, biological residues were dominant (up to 40%) during storms with relatively warm cloud temperatures (up to -15 °C), supporting the important role bioparticles can play as ice nucleating particles. On the other hand, lower percentages of residues from local biomass burning and pollution were observed over the three winter seasons (on average 31 and 9%, respectively). When precipitation quantities were relatively low, these insoluble residues most likely served as CCN, forming smaller more numerous cloud droplets at the base of shallow cloud systems, and resulting in less efficient riming processes. Ultimately, the goal is to use such observations to improve the mechanistic linkages between aerosol sources and precipitation processes to produce more accurate predictive weather forecast models and improve water resource management. © Author(s) 2015. CC Attribution 3.0 License."
"6602878057;7004479957;24722339600;7102294773;7403682442;57193213111;36183151300;8922308700;36876405100;8718425100;56521864800;25823927100;25652188900;28568055900;16550482700;57188966058;","Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: The VOCA intercomparison",2015,"10.5194/acp-15-153-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84920728055&doi=10.5194%2facp-15-153-2015&partnerID=40&md5=c282a1d4ffd2934fac94356cbdbb963a","A diverse collection of models are used to simulate the marine boundary layer in the southeast Pacific region during the period of the October-November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study Regional Experiment) field campaign. Regional models simulate the period continuously in boundary-forced free-running mode, while global forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared to extensive observations along a line at 20° S extending westward from the South American coast. Most of the models simulate cloud and aerosol characteristics and gradients across the region that are recognizably similar to observations, despite the complex interaction of processes involved in the problem, many of which are parameterized or poorly resolved. Some models simulate the regional low cloud cover well, though many models underestimate MBL (marine boundary layer) depth near the coast. Most models qualitatively simulate the observed offshore gradients of SO2, sulfate aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in concentration between the MBL and the free troposphere. Most models also qualitatively capture the decrease in cloud droplet number away from the coast. However, there are large quantitative intermodel differences in both means and gradients of these quantities. Many models are able to represent episodic offshore increases in cloud droplet number and aerosol concentrations associated with periods of offshore flow. Most models underestimate CCN (at 0.1% supersaturation) in the MBL and free troposphere. The GCMs also have difficulty simulating coastal gradients in CCN and cloud droplet number concentration near the coast. The overall performance of the models demonstrates their potential utility in simulating aerosol-cloud interactions in the MBL, though quantitative estimation of aerosol-cloud interactions and aerosol indirect effects of MBL clouds with these models remains uncertain. © © Author(s) 2015."
"57198856305;56416491200;7103319791;","Study of water cloud model vegetation descriptors in estimating soil moisture in Solani catchment",2015,"10.1002/hyp.10344","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84927691679&doi=10.1002%2fhyp.10344&partnerID=40&md5=66385106c02bdce6b4a27f006a32243d","Water cloud model (WCM) relates the backscatter coefficient (σo) with soil moisture. The backscatter coefficient includes the backscatter coefficient due to vegetation (σo<inf>veg</inf>), and the backscatter coefficient due to soil (σo<inf>soil</inf>). The σo<inf>veg</inf> of WCM depends upon vegetation characteristics. The present study is aimed to investigate the effect of different vegetation descriptors in estimating soil moisture from WCM. The study is carried out in Solani River catchment of India. Envisat Advanced Synthetic Aperture Radar (ASAR) images of three dates were acquired for the study. The field data, volumetric soil moisture from the upper 0-10cm soil layer, soil texture, soil surface roughness, leaf area index (LAI), leaf water area index, normalized plant water content and average plant height corresponding to satellite pass dates were collected. Genetic algorithm optimization technique is used to estimate the WCM vegetation parameters. The use of LAI as vegetation descriptor results in minimum root mean square error (RMSE) of 1.77dB between WCM computed backscatter and Envisat ASAR observed backscatter. Also, use of LAI in WCM as vegetation descriptor results in the least RMSE of 4.19%, between estimated and observed soil moisture for the first field campaign, whereas it was 5.64% for the last field campaign which was undertaken after 35days of first campaign. It is concluded that LAI can be treated as the best vegetation descriptor in studies retrieving soil moisture and backscatter from microwave remote sensing data. © 2014 John Wiley & Sons, Ltd."
"55740123300;7004606927;7004372407;35734505200;55963592900;","Energetics of persistent turbulent layers underneath mid-level clouds estimated from concurrent radar and radiosonde data",2014,"10.1016/j.jastp.2014.01.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84904804930&doi=10.1016%2fj.jastp.2014.01.005&partnerID=40&md5=0f92ac679ad5581f4830ab0c27bcfc46","Two Japanese-French field campaigns devoted to studying small-scale turbulence and instabilities in the lower atmosphere were conducted in September 2011 and November 2012 at the Shigaraki Middle and Upper atmosphere (MU) Observatory (34.85°N, 136.15°E; Japan). The Very High Frequency Middle and Upper atmosphere radar (MUR) was operated with a time resolution of the order of 10s in range imaging mode allowing echo power measurements at fine range-resolutions (typically, a few tens of meters). In addition, balloons instrumented with RS92G Vaisala radiosondes were launched from the observatory during the radar operations. From the raw data of temperature, pressure and humidity, temperature turbulent layers can be identified from the detection of overturns by using the Thorpe (1977) method. During the two campaigns, both radar and balloon data revealed turbulent layers of about 1.0km in depth, underneath mid-level clouds and meteorological frontal zones. They persisted for about 10h in the radar data. The balloon data collected were undoubtedly representative of the conditions met by the radar. Turbulence parameters associated with stably stratified flows were tentatively estimated by using different methods involving both radar and balloon observations for 4 balloon flights. These parameters included the Thorpe, buoyancy, and Ozmidov scales LT, LB and LO, potential and kinetic turbulent energies TPE and TKE, potential kinetic energy dissipation rates εP and εK and turbulent diffusivities Kθ. The turbulence scales were found to be consistent between each other within a factor of about 2. Energy dissipation rates of 0.6mW/kg were found for 3 cases and 0.06mW/kg for one case. © 2014 Elsevier Ltd."
"6701669739;57211301037;6701681018;6701606453;7202772927;","Combining satellite microwave radiometer and radar observations to estimate atmospheric heating profiles",2009,"10.1175/2009JCLI3020.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77649326338&doi=10.1175%2f2009JCLI3020.1&partnerID=40&md5=01140ab6198c17e2fdc71d5c35b24ef8","In this study, satellite passive microwave sensor observations from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) are utilized to make estimates of latent+eddy sensible heating rates (Q1-QR) where Q1 is the apparent heat source and QR is the radiative heating rate in regions of precipitation. The TMI heating algorithm (herein called TRAIN) is calibrated or ""trained"" using relatively accurate estimates of heating based on spaceborne Precipitation Radar (PR) observations collocated with the TMI observations over a one-month period. The heating estimation technique is based on a previously described Bayesian methodology, but with improvements in supporting cloud-resolving model simulations, an adjustment of precipitation echo tops to compensate formodel biases, and a separate scaling of convective and stratiform heating components that leads to an approximate balance between estimated vertically integrated condensation and surface precipitation. Estimates of Q1-QR from TMI compare favorably with the PR training estimates and show only modest sensitivity to the cloud-resolving model simulations of heating used to construct the training data. Moreover, the net condensation in the corresponding annual mean satellite latent heating profile is within a few percent of the annual mean surface precipitation rate over the tropical and subtropical oceans where the algorithm is applied. Comparisons of Q1 produced by combining TMI Q1-QR with independently derived estimates of QR show reasonable agreement with rawinsonde-based analyses ofQ1 from two field campaigns, although the satellite estimates exhibit heating profile structures with sharper and more intense heating peaks than the rawinsonde estimates. © 2009 American Meteorological Society."
"9536598800;57203492395;","Secondary initiation of multiple bands of cumulonimbus over southern Britain. II: Dynamics of sencondary initiation",2006,"10.1256/qj.05.152","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746218768&doi=10.1256%2fqj.05.152&partnerID=40&md5=bad5669dbc8a5d2e176b59af8703d1c9","The Convective Storm Initiation Project (CSIP) pilot field programme took place in the summer of 2004 in southern England. During this field campaign a case of a cold-pool outflow initiating an arc of convection downwind of the generating storm (the 'primary storm') was observed. Three further arcs were initiated further downwind of this first arc. These arcs all later gave significant rainfall over south-east England. Results from the modelling studies described in this paper show that gravity waves, generated by the 'primary storm', may have been responsible for initiating the further three arcs of convective showers that were observed. The modelled primary storm generates waves with a range of vertical wavelengths. These are separated by dispersion, with the higher-order modes (with the largest vertical wavelengths) travelling fastest (approximately 30 m s-1). The fastest two modes suppressed convection and later modes increased boundary-layer depth and so initiated convection. The multiple peaks (from non-hydrostatic effects) in the third mode may have been responsible for the two main arcs observed and the fourth mode may have been responsible for the third arc. The amplitude of the modelled waves at low levels was much larger downwind of the primary storm than upwind and only initiated convection there, which agrees with the observations of the arcs forming downwind of the primary storm. This asymmetry appears to be caused by the moving-wave source and asymmetric wave trapping. Finally we discuss the implications for numerical weather prediction (NWP). Reducing the resolution of the model, and varying the magnitude of the wind speed used, shows that a non-hydrostatic high-resolution (≃1 km) NWP model should be able to capture such wave processes, if the generating storm is forecast or analysed correctly. © Royal Meteorological Society, 2006."
"6507984183;7402370453;6701378450;","CCN predictions: Is theory sufficient for assessments of the indirect effect?",2006,"10.1029/2005GL025148","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646351964&doi=10.1029%2f2005GL025148&partnerID=40&md5=9666b3ec5849b6648d44c74d7b181f61","This study quantitatively assesses the sensitivity of cloud droplet number (CDNC) to errors in cloud condensation nuclei (CCN) predictions that arise from application of Köhler theory. The CDNC uncertainty is assessed by forcing a droplet activation parameterization with a comprehensive dataset of CCN activity and aerosol size and chemical composition obtained during the ICARTT field campaign in August 2004. Our analysis suggests that, for a diverse range of updraft velocity, droplet growth kinetics and airmass origin, the error in predicted CDNC is (at most) half of the CCN prediction error. This means that the typical 20-50% error in ambient CCN closure studies would result in a 10-25% error in CDNC. For the first time, a quantitative link between aerosol and CDNC prediction errors is available, and can be the basis of a robust uncertainty analysis of the first aerosol indirect effect. Copyright 2006 by the American Geophysical Union."
"7003265236;7005649482;7003886670;6701415209;7006686940;7004430325;7003967055;6603261697;7102653983;","Spatial and temporal variations in fluxes of energy, water vapour and carbon dioxide during OASIS 1994 and 1995",2004,"10.1023/A:1026028217081","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0742288510&doi=10.1023%2fA%3a1026028217081&partnerID=40&md5=cb77b2d520184b89dfdc5bafc47638c2","This paper introduces the micrometeorological field campaigns known as OASIS (Observations At Several Interacting Scales) and then summarizes several companion studies that have used the OASIS dataset. Instrumented towers, aircraft and atmospheric sondes were used for measurements over three paired sites (crops and pastures), approximately equi-spaced along an 88-km transect in south-eastern New South Wales, Australia, during the austral springs of 1994 and 1995. Measurements included standard meteorological data and the fluxes of solar and net radiation, sensible heat, water vapour and the greenhouse gases CO2, N2O, CH4. Descriptions of the site, and the spatial and temporal variations of climate fields and fluxes, are presented. There were strong contrasts in fluxes and surface conductances, evaporation ratios and water use efficiencies between the 1994 drought year and the normal rainfall year of 1995. Despite greater incoming solar radiation in 1994 associated with less cloud cover, net radiation was lower than in 1995 because of greater outgoing thermal radiation caused by higher surface temperatures. In 1994 daily sensible heat fluxes were about 50% higher and evaporation rates about half those for 1995. Rainfall in the three-month growing season prior to the field campaigns was the key determinant of leaf area index, surface conductances and the fluxes of sensible and latent heat and CO2. Antecedent rainfall distribution also controlled variation in fluxes and surface properties along the transect within each year. There was a net loss of CO2 to the atmosphere at the drier central sites in 1994, and a net uptake at the wetter north-eastern sites. Both sites recorded uptake of CO 2 in 1995, but values were lower at the central site than at the north-east site due to the strong rainfall gradient along the transect in the three months prior to each field campaign. Differences in fluxes between crops and pastures at each site were smaller than between sites."
"7004556087;35477504600;6601942466;57190244589;7005893321;","Surface tension of Rax cloud water and its relation to the concentration of organic material",2002,"10.1029/2002JD002506","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6444239183&doi=10.1029%2f2002JD002506&partnerID=40&md5=c53271dc8854a4d653b506ca6e1ac270","During an intensive field campaign at a midlevel (1640 m above sea level) mountain in central Europe, cloud water samples were collected using a cloud water sampler and subsequently analyzed for organic and inorganic ions, total carbon (TC), and black carbon (BC). Cloud water surface tension (σ) was measured using the ring method. Generally, the cloud water samples had surface tensions lower than that of pure water. The average value of σ was 95.2% of the σ of water, while the lowest value was 83.3%. A trend of lower a with higher concentrations of organic material (OC, obtained as TC-BC) was found at lower OC concentrations than those previously described [Charlson et al., 2001; Facchini et al., 1999a]. The effect of the lower σ on cloud droplet activation was modeled using Köhler theory. For an assumed dry sulphate nucleus with 0.05 μm diameter, the critical supersaturation would be decreased by 7% (average σ) and by 22% for minimum σ. Copyright 2002 by the American Geophysical Union."
"7004884101;7406215388;56273538700;7402074810;55675223302;","Profiler contributions to Tropical Rainfall Measuring Mission (TRMM) ground validation field campaigns",2002,"10.1175/1520-0426(2002)019<0843:PCTTRM>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036612954&doi=10.1175%2f1520-0426%282002%29019%3c0843%3aPCTTRM%3e2.0.CO%3b2&partnerID=40&md5=594c1a164ec80bd16f04a1893c63271f","Doppler radar profilers are widely used for routine measurement of wind, especially in the lower troposphere. The same profilers with minor modifications are useful tools for precipitation research. Specifically, the profilers are now increasingly being used to explore the structure of precipitating cloud systems and to provide calibration and validation of other instruments used in precipitation research, including scanning radars and active and passive satellite-borne sensors. A vertically directed profiler is capable of resolving the vertical structure of precipitating cloud systems that pass overhead. Standard profiler measurements include reflectivity, reflectivity- weighted Doppler velocity, and spectral width. This paper presents profiler observations of precipitating cloud systems observed during Tropical Rainfall Measuring Mission (TRMM) Ground Validation field campaigns. The observations show similarities and differences between convective systems observed in Florida; Brazil; and Kwajalein, Republic of the Marshall Islands. In addition, it is shown how a profiler can be calibrated using a collocated Joss-Waldvogel disdrometer, how the profiler can then be used to calibrate a scanning radar, and how the profiler may be used to retrieve drop size distributions."
"6603925960;7006577245;6701422868;35551238800;6602609406;7005421048;","Impact of cirrus cloud ice crystal shape and size on multiple scattering effects : Application to spaceborne and airborne backscatter lidar measurements during LITE mission and E LITE campaign",1999,"10.1029/1999GL900474","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032695557&doi=10.1029%2f1999GL900474&partnerID=40&md5=b2bee46bfe129c9d557acd1bcbb99674","Forward scattering in cirrus clouds can significantly affect backscatter lidar signal. Its contribution can be estimated numerically knowing the size and shape of the crystals. Contemporary airborne and space-borne lidar measurements collected during the European Lidar In-space Technology Experiment (E-LITE) field campaign (in the framework of the NASA/LITE mission) are used to show that forward scattering reduces the optical depth derived from space-borne measurements by at least a factor of 2 with respect to the true value. This reduction factor is discussed in terms of crystal size and shape (i.e. forward scattering, and measurement configuration). It is shown that cirrus backscatter-to-extinction ratios derived from airborne and space-borne lidar measurements can be used to illustrate the sensitivity of multiple scattering effects the ice crystal size and shape. Copyright 1999 by the American Geophysical Union."
"14018610000;8511991900;24450860900;57189999417;7103158465;57193882808;56256173900;6603211582;56611485900;56439778100;55731303900;7103370302;6506385754;7005729142;7004242319;7201888941;","Idealized simulations of a squall line from the MC3E field campaign applying three bin microphysics schemes: Dynamic and thermodynamic structure",2017,"10.1175/MWR-D-16-0385.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040467332&doi=10.1175%2fMWR-D-16-0385.1&partnerID=40&md5=0f64938d48a5a41cbdcbb030f8a4aaab","The squall-line event on 20 May 2011, during the Midlatitude Continental Convective Clouds (MC3E) field campaign has been simulated by three bin (spectral) microphysics schemes coupled into the Weather Research and Forecasting (WRF) Model. Semi-idealized three-dimensional simulations driven by temperature and moisture profiles acquired by a radiosonde released in the preconvection environment at 1200 UTC in Morris, Oklahoma, show that each scheme produced a squall line with features broadly consistent with the observed storm characteristics. However, substantial differences in the details of the simulated dynamic and thermodynamic structure are evident. These differences are attributed to different algorithms and numerical representations of microphysical processes, assumptions of the hydrometeor processes and properties, especially ice particle mass, density, and terminal velocity relationships with size, and the resulting interactions between the microphysics, cold pool, and dynamics. This study shows that different bin microphysics schemes, designed to be conceptually more realistic and thus arguably more accurate than bulk microphysics schemes, still simulate a wide spread of microphysical, thermodynamic, and dynamic characteristics of a squall line, qualitatively similar to the spread of squall-line characteristics using various bulk schemes. Future work may focus on improving the representation of ice particle properties in bin schemes to reduce this uncertainty and using the similar assumptions for all schemes to isolate the impact of physics from numerics. © 2017 American Meteorological Society."
"23019619200;56060986400;56250185400;","Harmattan, Saharan heat low, and West African monsoon circulation: Modulations on the Saharan dust outflow towards the North Atlantic",2017,"10.5194/acp-17-10223-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028702917&doi=10.5194%2facp-17-10223-2017&partnerID=40&md5=9425a0cc2571eed443bc2af47955e731","The outflow of dust from the northern African continent towards the North Atlantic is stimulated by the atmospheric circulation over North Africa, which modulates the spatio-temporal distribution of dust source activation and consequently the entrainment of mineral dust into the boundary layer, as well as the transport of dust out of the source regions. The atmospheric circulation over the North African dust source regions, predominantly the Sahara and the Sahel, is characterized by three major circulation regimes: (1) the harmattan (trade winds), (2) the Saharan heat low (SHL), and (3) the West African monsoon circulation. The strength of the individual regimes controls the Saharan dust outflow by affecting the spatio-temporal distribution of dust emission, transport pathways, and deposition fluxes.<br><br>This study aims at investigating the atmospheric circulation pattern over North Africa with regard to its role favouring dust emission and dust export towards the tropical North Atlantic. The focus of the study is on summer 2013 (June to August), during which the SALTRACE (Saharan Aerosol Long-range TRansport and Aerosol-Cloud interaction Experiment) field campaign also took place. It involves satellite observations by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) flying on board the geostationary Meteosat Second Generation (MSG) satellite, which are analysed and used to infer a data set of active dust sources. The spatio-temporal distribution of dust source activation frequencies (DSAFs) allows for linking the diurnal cycle of dust source activations to dominant meteorological controls on dust emission. In summer, Saharan dust source activations clearly differ from dust source activations over the Sahel regarding the time of day when dust emission begins. The Sahara is dominated by morning dust source activations predominantly driven by the breakdown of the nocturnal low-level jet. In contrast, dust source activations in the Sahel are predominantly activated during the second half of the day, when downdrafts associated with deep moist convection are the major atmospheric driver. Complementary to the satellite-based analysis on dust source activations and implications from their diurnal cycle, simulations on atmosphere and dust life cycle were performed using the mesoscale atmosphere-dust model system COSMO-Muscat (COSMO: COnsortium for Small-scale MOdelling; Muscat: MUltiScale Chemistry Aerosol Transport Model). Fields from this simulation were analysed regarding the variability of the harmattan, the Saharan heat low, and the monsoon circulation as well as their impact on the variability of the Saharan dust outflow towards the North Atlantic. This study illustrates the complexity of the interaction among the three major circulation regimes and their modulation of the North African dust outflow. Enhanced westward dust fluxes frequently appear following a phase characterized by a deep SHL. Ultimately, findings from this study contribute to the quantification of the interannual variability of the atmospheric dust burden. © Author(s) 2017."
"57193574176;7004174939;7003478309;18134565600;16834406100;36169987900;7201953443;8643810200;37037211400;24578264300;","Retrievals of aerosol optical and microphysical properties from Imaging Polar Nephelometer scattering measurements",2017,"10.5194/amt-10-811-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015042187&doi=10.5194%2famt-10-811-2017&partnerID=40&md5=47cf95f9194bdb76267b3447809fce2f","A method for the retrieval of aerosol optical and microphysical properties from in situ light-scattering measurements is presented and the results are compared with existing measurement techniques. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to airborne and laboratory measurements made by a novel polar nephelometer. This instrument, the Polarized Imaging Nephelometer (PI-Neph), is capable of making high-accuracy field measurements of phase function and degree of linear polarization, at three visible wavelengths, over a wide angular range of 3 to 177°. The resulting retrieval produces particle size distributions (PSDs) that agree, within experimental error, with measurements made by commercial optical particle counters (OPCs). Additionally, the retrieved real part of the refractive index is generally found to be within the predicted error of 0.02 from the expected values for three species of humidified salt particles, with a refractive index that is well established. The airborne measurements used in this work were made aboard the NASA DC-8 aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign, and the inversion of this data represents the first aerosol retrievals of airborne polar nephelometer data. The results provide confidence in the real refractive index product, as well as in the retrieval's ability to accurately determine PSD, without assumptions about refractive index that are required by the majority of OPCs. © The Author(s) 2017."
"57195436634;35219491500;10041603900;57033288300;57194177039;57115644400;55732032000;57169470500;57195432807;57194177306;57169013100;7405273411;7407084420;","Evolution of microphysical structure of a subtropical squall line observed by a polarimetric radar and a disdrometer during OPACC in Eastern China",2017,"10.1002/2016JD026346","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028028704&doi=10.1002%2f2016JD026346&partnerID=40&md5=844be9d90bca3d17dcff0a905940352b","The evolution of the microphysical structures of a subtropical squall line observed during the Observation, Prediction and Analysis of Severe Convection of China (OPACC) field campaign in Eastern China is documented in this paper. The data collected from a C-band, polarimetric Doppler radar (reflectivity Z, differential reflectivity ZDR, and specific differential phase KDP) and a disdrometer are used to investigate the variations of microphysical characteristics within the convective region during the formative, intensifying, and mature stages of the squall line. The microphysical characteristics of the squall line are noticeably different among these three stages. When the squall line develops from the formative stage to the mature stage, its radar-derived drop size distribution (DSD) in the convective region evolves from continental-like convection to more maritime-like convection. Contrary to previous studies, the DSD characteristics of a convective line may not be simply locked to a geographical location but varied extensively throughout its life cycle. The polarimetric radar-derived liquid water content below the freezing level in the convective region is 3 times higher than the ice water content above the freezing level. This, in conjunction with a low cloud base (~0.68 km) and a high freezing level (~5 km), indicates a deep warm cloud layer and the dominance of the warm rain process within this squall line. © 2017. American Geophysical Union. All Rights Reserved."
"22234129400;7405489798;","MJO moisture budget during DYNAMO in a cloud-resolving model",2016,"10.1175/JAS-D-14-0379.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976416796&doi=10.1175%2fJAS-D-14-0379.1&partnerID=40&md5=7d8ffac20cc51bcc5c3b83d16a05b85e","Contributions by different physical processes and cloud types to the sum of the large-scale vertical moisture advection and apparent moisture sink observed by the DYNAMO field campaign northern sounding array during the passage of a Madden-Julian oscillation (MJO) event are estimated using a cloud-resolving model. The sum of these two moisture budget terms is referred to as the column-confined moisture tendency MC. Assuming diabatic balance, the contribution of different physical processes and cloud types to the large-scale vertical velocity and MC can be estimated using simulated diabatic tendencies and the domain-averaged static stability and vertical moisture gradient. Low-level moistening preceding MJO passage is captured by MC and dominated by the effects of shallow clouds. Because of the large vertical moisture gradient at this level, condensational heating in these clouds generates ascent and vertical moisture advection overwhelming the removal of water vapor by condensation. Shallow convective eddy transport also contributes to low-level moistening during this period. Eddy transport by congestus and deep convective clouds contributes to subsequent mid- and upper-level moistening, respectively, as well as low-level drying. Because the upper-level vertical moisture gradient is small, ice deposition within stratiform clouds has a net drying effect. The weak eddy transport in stratiform clouds is unable to compensate for this drying. Nonprecipitating clouds mainly modulate MC through their effects on radiation. During the enhanced phase, reduced longwave cooling results in less subsidence and drying; the opposite occurs during the suppressed phase. Large-scale horizontal advection, which is not included in MC, is responsible for much of the drying during the dissipating phase. © 2016 American Meteorological Society."
"7410255460;25823818000;57194974100;7006669087;23017945100;6602375917;6602623584;36646089600;55546194900;57188860262;","Aircraft observations of dry air, the itcz, convective cloud systems, and cold pools in MJO during dynamo",2016,"10.1175/BAMS-D-13-00196.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963860836&doi=10.1175%2fBAMS-D-13-00196.1&partnerID=40&md5=613a0cca2996cf4029c1f410ff5a4da6","A major international field campaign supported by the Dynamics of the Madden?Julian Oscillation (DYNAMO), the Cooperative Indian Ocean Experiment on Intraseasonal Variability (CINDY), the Atmospheric Radiation Measurement Program (ARM) MJO Investigation Experiment (AMIE), and the Littoral Air-Sea Processes (LASP) programs took place over the Indian Ocean with an intensive observing period (IOP) from 1 October 2011 to 15 January 2012. The mobility of the aircraft proves to be vital in capturing some key features, such as the spatial distribution of the large-scale water vapor and the small-scale SST variations associated with convective cold pools, filling a gap from the ship- and land-based station observations. It was found that dry air intrusions from the subtropics may suppress convection in the ITCZ, which is favorable for the onset of the equatorial convection during MJO initiation. Distinct characteristics were found in the convective structure and microphysical properties of MCSs during the suppressed, transition/onset, and active phases of the MJO. The atmospheric boundary layer depth and upper-ocean temperature are higher during the suppressed phase than during the active phase, and the air?sea temperature difference and sensible fluxes are larger during the suppressed phase of the MJO."
"35113492400;56611366900;55738957800;56129452400;55272477500;54931339600;56526794400;57126548600;","Improving parameterization of entrainment rate for shallow convection with aircraft measurements and large-eddy simulation",2016,"10.1175/JAS-D-15-0050.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958622249&doi=10.1175%2fJAS-D-15-0050.1&partnerID=40&md5=126707c76447597b625ad59d4e716fa6","This work examines the relationships of entrainment rate to vertical velocity, buoyancy, and turbulent dissipation rate by applying stepwise principal component regression to observational data from shallow cumulus clouds collected during the Routine Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign over the ARM Southern Great Plains (SGP) site near Lamont, Oklahoma. The cumulus clouds during the RACORO campaign simulated using a large-eddy simulation (LES) model are also examined with the same approach. The analysis shows that a combination of multiple variables can better represent entrainment rate in both the observations and LES than any single-variable fitting. Three commonly used parameterizations are also tested on the individual cloud scale. A new parameterization is thus presented that relates entrainment rate to vertical velocity, buoyancy, and dissipation rate; the effects of treating clouds as ensembles and humid shells surrounding cumulus clouds on the new parameterization are discussed. Physical mechanisms underlying the relationships of entrainment rate to vertical velocity, buoyancy, and dissipation rate are also explored. © 2016 American Meteorological Society."
"22933265100;","On the ice nucleation spectrum",2012,"10.5194/acp-12-3733-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860187310&doi=10.5194%2facp-12-3733-2012&partnerID=40&md5=a280f09f73a6b93944b0cde1fa19866b","This work presents a novel formulation of the ice nucleation spectrum, i.e. the function relating the ice crystal concentration to cloud formation conditions and aerosol properties. The new formulation is physically-based and explicitly accounts for the dependency of the ice crystal concentration on temperature, supersaturation, cooling rate, and particle size, surface area and composition. This is achieved by introducing the concepts of ice nucleation coefficient (the number of ice germs present in a particle) and nucleation probability dispersion function (the distribution of ice nucleation coefficients within the aerosol population). The new formulation is used to generate ice nucleation parameterizations for the homogeneous freezing of cloud droplets and the heterogeneous deposition ice nucleation on dust and soot ice nuclei. For homogeneous freezing, it was found that by increasing the dispersion in the droplet volume distribution the fraction of supercooled droplets in the population increases. For heterogeneous ice nucleation the new formulation consistently describes singular and stochastic behavior within a single framework. Using a fundamentally stochastic approach, both cooling rate independence and constancy of the ice nucleation fraction over time, features typically associated with singular behavior, were reproduced. Analysis of the temporal dependency of the ice nucleation spectrum suggested that experimental methods that measure the ice nucleation fraction over few seconds would tend to underestimate the ice nuclei concentration. It is shown that inferring the aerosol heterogeneous ice nucleation properties from measurements of the onset supersaturation and temperature may carry significant error as the variability in ice nucleation properties within the aerosol population is not accounted for. This work provides a simple and rigorous ice nucleation framework where theoretical predictions, laboratory measurements and field campaign data can be reconciled, and that is suitable for application in atmospheric modeling studies. © 2012 Author(s)."
"7006861646;23977377900;22956930200;6603651431;57208461039;7801577502;6507876616;35766145000;6508369265;35264733400;36054649900;35729333400;6507594716;7801336936;6701633912;","On the water and energy cycles in the Tropics",2010,"10.1016/j.crte.2010.01.003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77951620665&doi=10.1016%2fj.crte.2010.01.003&partnerID=40&md5=9e5884de19bc6fc48f2cee5a414ee310","The water and energy cycles are major elements of the Earth climate. These cycles are especially active in the intertropical belt where satellites provide the most suitable observational platform. The history of Earth observations of the water cycle and of the radiation budget viewed from space reveals that the fundamental questions from the early times are still relevant for today's research. The last 2 decades have seen a number of milestones regarding the documentation of rainfall, mesoscale convective systems (MCS), water vapour and radiation at the top of the atmosphere (TOA). Beyond dedicated missions that provided enhanced characterizations of some elements of the atmospheric water cycle and field campaigns that allowed the gathering of validation data, the advent of the long record of meteorological satellites lead to new questioning on the homogenisation of the data time series, etc. The use of this record to document the tropical climate brought new results of the distribution of humidity and reinforced the understanding of some robust features of the African monsoon. Challenges for the immediate future concerns the deepening of the understanding of the role of cloud systems in the monsoon circulation, the downscaling of the documentation of the water and energy cycle at the scale of these cloud systems, the research of better adequation between the users and the satellite estimate of rainfall and finally a much needed methodological effort to build exploitable time series for the estimation of climatic trends in the water and energy cycle in the Tropics. The required observations to address these challenges are rapidly presented with emphasis on the upcoming Megha-Tropiques (MT) mission. © 2010 Académie des sciences."
"11940687600;7102632172;7006565753;9940496700;9243836500;11940257300;","Three-dimensional wind retrieval: Application of MUSCAT to dual-Doppler lidar",2009,"10.1175/2008JTECHA1115.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65549100134&doi=10.1175%2f2008JTECHA1115.1&partnerID=40&md5=4a06f36642d35424b3e26414b4d13f8d","During the field campaign of the Terrain-induced Rotor Experiment (T-REX) in the spring of 2006, Doppler lidar measurements were taken in the complex terrain of the Californian Owens Valley for six weeks. While fast three-dimensional (3D) wind analysis from measured radial wind components is well established for dual weather radars, only the feasibility was shown for dual-Doppler lidars. A computationally inexpensive, variational analysis method developed for multiple-Doppler radar measurements over complex terrain was applied. The general flow pattern of the 19 derived 3D wind fields is slightly smoothed in time and space because of lidar scan duration and analysis algorithm. The comparison of extracted wind profiles to profiles from radiosondes and wind profiler reveals differences of wind speed and direction of less than 1.1 m s-1 and 3°, on average, with standard deviations not exceeding 2.7 m s-1 and 27°, respectively. Standard velocity-azimuth display (VAD) retrieval method provided higher vertical resolution than the dual-Doppler retrieval, but no horizontal structure of the flow field. The authors suggest a simple way to obtain a good first guess for a dual-lidar scan strategy geared toward 3D wind retrieval that minimizes scan duration and maximizes spatial coverage. © 2009 American Meteorological Society."
"7003729315;7003591311;7003666669;7006634316;7102654014;55207447000;21646972800;","Preface to special section: Atmospheric Radiation Measurement Program May 2003 Intensive Operations Period examining aerosol properties and radiative influences",2006,"10.1029/2005JD006908","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646339665&doi=10.1029%2f2005JD006908&partnerID=40&md5=d9cd39ed212ea9e0b60d746e329a244a","Atmospheric aerosols influence climate by scattering and absorbing radiation in clear air (direct effects) and by serving as cloud condensation nuclei, modifying the microphysical properties of clouds, influencing radiation and precipitation development (indirect effects). Much of present uncertainty in forcing of climate change is due to uncertainty in the relations between aerosol microphysical and optical properties and their radiative influences (direct effects) and between microphysical properties and their ability to serve as cloud condensation nuclei at given supersaturations (indirect effects). This paper introduces a special section that reports on a field campaign conducted at the Department of Energy Atmospheric Radiation Measurement site in north central Oklahoma in May 2003, examining these relations using in situ airborne measurements and surface-, airborne-, and space-based remote sensing. Copyright 2006 by the American Geophysical Union."
"7006253164;7003815387;57197506907;23019544500;","Attenuation of spectal actinic flux and photolysis frequencies at the surface through homogenous cloud fields",2004,"10.1029/2003JD004076","https://www.scopus.com/inward/record.uri?eid=2-s2.0-9144259211&doi=10.1029%2f2003JD004076&partnerID=40&md5=4e3784e318573f8e70b1a67818dc4446","The effect of clouds on derived photolysis rates has been investigated using actinic flux spectra measured from a 2π sr diode-array spectral radiometer deployed in a series of differing field campaigns. Homogenously cloudy and clear days were selected, and ratios of cloudy-to-clear actinic flux spectra were used to derive a cloud transmittance slope (CTS), which is calculated as the gradient of the cloudy/clear ratio plot at 340 &lt; λ &lt; 420 nm. CTS is a measure of the wavelength dependence of actinic flux attenuation by clouds and shows an approximately linear dependence with solar zenith angle. When the solar zenith angle is high, the CTS is largest because of the enhanced path length of radiation through the scattering medium. The dependence of measured CTS under a range of atmospheric conditions is explored; the slopes of the CT being rationalized in terms of the cloud optical depth and single scattering albedo of the cloud. The appearance of a short-wave enhancement in CT in a multiple scattering environment is noted in agreement with theory. The photolysis frequency coefficients j(O1D) and j(NO2), calculated from the measured actinic fluxes, are compared to observe the effect of wavelength-dependent attenuation of actinic flux on photochemical reactions. After the subtraction of the effect of changing overhead ozone column, the effect of cloud was quite variable in that j(NO 2) was found to be reduced to a greater extent than j(O1D) by some clouds or vice versa depending on the individual case. The results clearly demonstrate that photolysis frequencies in the UVB and UVA do not vary linearly under different atmospheric conditions in a cloudy field. Copyright 2004 by the American Geophysical Union."
"7403129512;7408612236;","High-resolution estimates of total solar and PAR surface fluxes over large-scale BOREAS study area from GOES measurements",1997,"10.1029/96JD03706","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031448712&doi=10.1029%2f96JD03706&partnerID=40&md5=1d916e78997bf3ac4eaf9dd403ea8a5e","A published physical algorithm designed for estimating total solar and photosynthetically active radiation (PAR) fluxes at the Earth's surface from GOES visible imagery has been modified for the Boreal Ecosystem-Atmosphere Study (BOREAS) applications at high space and time resolutions (1 km/half-hourly). Substantive changes to the algorithm are described, along with descriptions of various additional features needed to apply the algorithm over the boreal forest. Because of the propensity of forest fire smoke to impact the BOREAS study area during the summer period, particular attention has been given to the treatment of aerosol effects. To validate the algorithm, instantaneous estimates of downwelling total solar and PAR fluxes at half-hourly time steps obtained from a GOES 7 data set are compared with 15-min averaged in situ radiometer measurements obtained during the second summer intensive field campaign of 1994 from the array of BOREAS automatic meteorological stations. The validation results have been stratified according to sky conditions to help understand the detailed nature of algorithm performance and to identify weaknesses in the current algorithm design. A variety of sensitivity tests have also been conducted to help evaluate the algorithm's strengths and weaknesses. In addition, a large-scale analysis of the retrievals over the five 1994 field campaigns has been carried out to provide background information for modelers on the nature of the solar component of the surface radiation budget' across the boreal forest zone. The overall accuracies of the algorithm are 1.6% and 6.5% for total solar and PAR fluxes, with relative precisions of ∼20% considering all days, including those with extensive cloud cover and/or high concentrations of forest fire smoke. Such precisions are consistent with current published expectations at an hourly timescale. Better precisions of around 7% are found for clear, relatively aerosol-free days, which represents noteworthy algorithm performance in terms of expectations at these timescales. Copyright 1997 by the American Geophysical Union."
"6602515941;22236015300;56690386600;","Quantifying the effect of riming on snowfall using ground-based observations",2017,"10.1002/2016JD026272","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017620827&doi=10.1002%2f2016JD026272&partnerID=40&md5=51dd30e52c4a316080d2e0a6706f7110","Ground-based observations of ice particle size distribution and ensemble mean density are used to quantify the effect of riming on snowfall. The rime mass fraction is derived from these measurements by following the approach that is used in a single ice-phase category microphysical scheme proposed for the use in numerical weather prediction models. One of the characteristics of the proposed scheme is that the prefactor of a power law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent does not change. To derive the rime mass fraction, a mass-dimensional relation representative of unrimed snow is also determined. To check the validity of the proposed retrieval method, the derived rime mass fraction is converted to the effective liquid water path that is compared to microwave radiometer observations. Since dual-polarization radar observations are often used to detect riming, the impact of riming on dual-polarization radar variables is studied for differential reflectivity measurements. It is shown that the relation between rime mass fraction and differential reflectivity is ambiguous, other factors such as change in median volume diameter need also be considered. Given the current interest on sensitivity of precipitation to aerosol pollution, which could inhibit riming, the importance of riming for surface snow accumulation is investigated. It is found that riming is responsible for 5% to 40% of snowfall mass. The study is based on data collected at the University of Helsinki field station in Hyytiälä during U.S. Department of Energy Biogenic Aerosols Effects on Clouds and Climate (BAECC) field campaign and the winter 2014/2015. In total 22 winter storms were analyzed, and detailed analysis of two events is presented to illustrate the study. © 2017. American Geophysical Union. All Rights Reserved."
"57189853742;7203054240;35609878300;55688847100;","Seasonal variation of shallow-to-deep convection transition and its link to the environmental conditions over the Central Amazon",2017,"10.1002/2016JD025993","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014678743&doi=10.1002%2f2016JD025993&partnerID=40&md5=eb1a14c058f6585987e1144c9f927198","This study aims to characterize the seasonal variation of the shallow-to-deep convection transition and understand how environmental conditions impact the behavior of this transition using data collected from the Observations and Modeling of the Green Ocean Amazon (GOAmazon) field campaign in the Central Amazon (Manaus). The diurnal cycle of the rain/cloud fraction shows that the wet season has more extensive shallow convection before the transition to deep convection with larger fractional coverage and rainfall; deep convection in the transition season is more intense and has higher vertical extension and a stronger updraft. Surface meteorology, atmospheric moisture, instability, and wind shear are contrasted for the shallow/congestus convection (SC) cases and the locally formed shallow-to-deep convection transition (LD) cases. The comparisons suggest that occurrence of the LD is generally promoted under the conditions of high atmospheric moisture and instability but has a weaker dependence on wind shear. The relative importance of these environmental controls also varies in different seasons: The dry and transition seasons require a deeper moist layer from the boundary layer to midtroposphere than the wet season; convective available potential energy (CAPE) is higher during the transition season, but it is a less important factor for shallow-to-deep convection transition than in other seasons; LD only has significantly larger wind shears than SC during the dry season. © 2017. American Geophysical Union. All Rights Reserved."
"55258548500;57200702127;56158925300;56158523800;56611366900;7404865816;","Distinct impacts of aerosols on an evolving continental cloud complex during the RACORO field campaign",2016,"10.1175/JAS-D-15-0361.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988318561&doi=10.1175%2fJAS-D-15-0361.1&partnerID=40&md5=a290aee1fe086fa38c564f6bffc0ab14","A continental cloud complex, consisting of shallow cumuli, a deep convective cloud (DCC), and stratus, is simulated by a cloud-resolving Weather Research and Forecasting Model to investigate the aerosol microphysical effect (AME) and aerosol radiative effect (ARE) on the various cloud regimes and their transitions during the Department of Energy Routine Atmospheric Radiation Measurement Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) campaign. Under an elevated aerosol loading with AME only, a reduced cloudiness for the shallow cumuli and stratus resulted from more droplet evaporation competing with suppressed precipitation, but an enhanced cloudiness for the DCC is attributed to more condensation. With the inclusion of ARE, the shallow cumuli are suppressed owing to the thermodynamic effects of light-absorbing aerosols. The responses of DCC and stratus to aerosols are monotonic with AME only but nonmonotonic with both AME and ARE. The DCC is invigorated because of favorable convection and moisture conditions at night induced by daytime ARE, via the so-called aerosol-enhanced conditional instability mechanism. The results reveal that the overall aerosol effects on the cloud complex are distinct from the individual cloud types, highlighting that the aerosol-cloud interactions for diverse cloud regimes and their transitions need to be evaluated to assess the regional and global climatic impacts. © 2016 American Meteorological Society."
"54417754700;22954523900;7003375617;55444637900;8927405700;","Relationship between temperature and apparent shape of pristine ice crystals derived from polarimetric cloud radar observations during the ACCEPT campaign",2016,"10.5194/amt-9-3739-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982103456&doi=10.5194%2famt-9-3739-2016&partnerID=40&md5=dab242098972c4ec39df396010018117","This paper presents first quantitative estimations of apparent ice particle shape at the top of liquid-topped clouds. Analyzed ice particles were formed under mixed-phase conditions in the presence of supercooled water and in the temperature range from-20 to-3°C. The estimation is based on polarizability ratios of ice particles measured by a Ka-band cloud radar MIRA-35 with hybrid polarimetric configuration. Polarizability ratio is a function of the geometrical axis ratio and the dielectric properties of the observed hydrometeors. For this study, 22 cases observed during the ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques) field campaign were used. Polarizability ratios retrieved for cloud layers with the cloud-top temperatures of ∼-5, ∼-8, ∼-15, and ∼-20°C were 1.6, 0.9, 0.6, and 0.9, respectively. Such values correspond to prolate, quasi-isotropic, oblate, and quasi-isotropic particles, respectively. Data from a free-fall chamber were used for the comparison. A good agreement of detected apparent shapes with well-known shape-temperature dependencies observed in laboratories was found. Polarizability ratios used for the analysis were estimated for areas located close to the cloud top, where aggregation and riming processes do not strongly affect ice particles. We concluded that, in microwave scattering models, ice particles detected in these areas can be assumed to have pristine shapes. It was also found that even slight variations of ambient conditions at the cloud top with temperatures warmer than ∼-5°C can lead to rapid changes of ice crystal shape. © 2016 Author(s)."
"55314628400;7102913661;7006329853;7102336894;35105101800;7103158465;56591838400;57188971800;7005054220;7404327420;57188966058;7006497590;8261329600;14048087800;56102834700;57194083102;7006025236;57188963068;56704589000;8359591200;57197517376;34568423700;35307051000;7003468369;7004165697;6506458269;","Wet scavenging of soluble gases in DC3 deep convective storms using WRF-Chem simulations and aircraft observations",2016,"10.1002/2015JD024623","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964389153&doi=10.1002%2f2015JD024623&partnerID=40&md5=14108a00b1f800cc4b632ac6c86e62e8","We examine wet scavenging of soluble trace gases in storms observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. We conduct high-resolution simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem) of a severe storm in Oklahoma. The model represents well the storm location, size, and structure as compared with Next Generation Weather Radar reflectivity, and simulated CO transport is consistent with aircraft observations. Scavenging efficiencies (SEs) between inflow and outflow of soluble species are calculated from aircraft measurements and model simulations. Using a simple wet scavenging scheme, we simulate the SE of each soluble species within the error bars of the observations. The simulated SEs of all species except nitric acid (HNO3) are highly sensitive to the values specified for the fractions retained in ice when cloud water freezes. To reproduce the observations, we must assume zero ice retention for formaldehyde (CH2O) and hydrogen peroxide (H2O2) and complete retention for methyl hydrogen peroxide (CH3OOH) and sulfur dioxide (SO2), likely to compensate for the lack of aqueous chemistry in the model. We then compare scavenging efficiencies among storms that formed in Alabama and northeast Colorado and the Oklahoma storm. Significant differences in SEs are seen among storms and species. More scavenging of HNO3 and less removal of CH3OOH are seen in storms with higher maximum flash rates, an indication of more graupel mass. Graupel is associated with mixed-phase scavenging and lightning production of nitrogen oxides (NOx), processes that may explain the observed differences in HNO3 and CH3OOH scavenging. © 2016. American Geophysical Union. All Rights Reserved."
"7404187535;7006029393;40461229800;56828858800;36452936000;7005773698;","The impacts of California's San Francisco Bay Area gap on precipitation observed in the Sierra Nevada during HMT and calwater",2015,"10.1175/JHM-D-14-0160.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84941286103&doi=10.1175%2fJHM-D-14-0160.1&partnerID=40&md5=6bb21bf0d13c0293877351018d29ff7a","Atmospheric rivers (ARs) are narrow regions of enhanced water vapor transport, usually found on the warm-sector side of the polar cold front in many midlatitude storms formed primarily over the oceans. Nonbrightband (NBB) rain is a shallow orographic rainfall process driven by collision and coalescence that has been observed in some of these storms. NBB rain accounts for about one-third, on average, of the total winter season rainfall occurring at a coastal mountain site in Northern California. During the California Energy Commission's CalWater project, nearly the same fraction of NBB rain was observed at a northern Sierra Nevada foothills site as compared to the coastal mountains, whereas less than half of the fractional amount of NBB rain was observed at a southern Sierra Nevada foothills site. Both Sierra Nevada sites often experience terrain-induced blocked flow, that is, Sierra barrier jet (SBJ) during landfalling winter storms. However, the northern Sierra Nevada site often is oriented geographically downwind of a gap in the coastal terrain near San Francisco duringARlandfall. This gap allows maritime air in theARto arrive at the northern site and enhance the collision-coalescence process in orographic feeder clouds as compared with the southern site. As a result, a greater amount and intensity of NBB rain and overall precipitation was produced at the northern site. This study uses a variety of observations collected in the coastal and Sierra Nevada ranges from the Hydrometeorology Testbed and CalWater field campaigns to document this behavior. A detailed case study provides additional context on the interaction between AR flow, the SBJ, and precipitation processes. © 2015 American Meteorological Society."
"55232897900;7004479957;24722339600;55802199600;","Aircraft observations of aerosol, cloud, precipitation, and boundary layer properties in pockets of open cells over the southeast Pacific",2014,"10.5194/acp-14-8071-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84906071061&doi=10.5194%2facp-14-8071-2014&partnerID=40&md5=9dee067815ce4bf071ae6c1f2c69069d","Five pockets of open cells (POCs) are studied using aircraft flights from the VOCALS Regional Experiment (VOCALS-REx), conducted in October and November 2008 over the southeast Pacific Ocean. Satellite imagery from the geostationary satellite GOES-10 is used to distinguish POC areas, and measurements from the aircraft flights are used to compare aerosol, cloud, precipitation, and boundary layer conditions inside and outside of POCs. Conditions observed across individual POC cases are also compared. <br><br> POCs are observed in boundary layers with a wide range of inversion heights (1250 to 1600 m) and surface wind speeds (5 to 11 m s&minus;1) and show no remarkable difference from the observed surface and free-tropospheric conditions during the two months of the field campaign. In all cases, compared to the surrounding overcast region the POC boundary layer is more decoupled, supporting both thin stratiform and deeper cumulus clouds. Although cloud-base precipitation rates are higher in the POC than the overcast region in each case, a threshold precipitation rate that differentiates POC precipitation from overcast precipitation does not exist. Mean cloud-base precipitation rates in POCs can range from 1.7 to 5.8 mm d&minus;1 across different POC cases. The occurrence of heavy drizzle (> 0 dBZ) lower in the boundary layer better differentiates POC precipitation from overcast precipitation, likely leading to the more active cold pool formation in POCs. Cloud droplet number concentration is at least a factor of 8 smaller in the POC clouds, and the ratio of drizzle water to cloud water in POC clouds is over an order of magnitude larger than that in overcast clouds, indicating an enhancement of collision-coalescence processes in POC clouds. <br><br> Despite large variations in the accumulation-mode aerosol concentrations observed in the surrounding overcast region (65 to 324 cm&minus;3), the accumulation-mode aerosol concentrations observed in the subcloud layer of all five POCs exhibit a much narrower range (24 to 40 cm&minus;3), and cloud droplet concentrations within the cumulus updrafts originating in this layer reflect this limited variability. Above the POC subcloud layer exists an ultraclean layer with accumulation-mode aerosol concentrations < 5 cm&minus;3, demonstrating that in-cloud collision-coalescence processes efficiently remove aerosols. The existence of the ultraclean layer also suggests that the major source of accumulation-mode aerosols, and hence of cloud condensation nuclei in POCs, is the ocean surface, while entrainment of free-tropospheric aerosols is weak. The measurements also suggest that at approximately 30 cm&minus;3 a balance of surface source and coalescence scavenging sinks of accumulation-mode aerosols maintain the narrow range of observed subcloud aerosol concentrations. © Author(s) 2014."
"35225532800;36661206400;7410177774;7102062952;12782225200;55682843800;56306791300;15922942700;8941151400;16047956100;7004473110;6603894019;7202674824;35085374900;56158229700;","New particle formation and growth in an isoprene-dominated ozark forest: From sub-5 nm to CCN-active sizes",2014,"10.1080/02786826.2014.984801","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84918558979&doi=10.1080%2f02786826.2014.984801&partnerID=40&md5=977b3700200bc05566da741bb9c39daf","Particle Investigations at a Northern Ozarks Tower: NOx, Oxidant, Isoprene Research (PINOT NOIR) were conducted in a Missouri forest dominated by isoprene emissions from May to October 2012. This study presents results of new particle formation (NPF) and the growth of new particles to cloud condensation nuclei (CCN)-active sizes (∼100 nm) observed during this field campaign. The measured sub-5 nm particles were up to ∼20,000 cm-3 during a typical NPF event. Nucleation rates J1 were relatively high (11.0 ± 10.6 cm-3 s-1), and one order of magnitude higher than formation rates of 5 nm particles (J5). Sub-5 nm particle formation events were observed during 64% of measurement days, with a high preference in biogenic volatile organic compounds (BVOCs)- and SO2-poor northwesterly (90%) air masses than in BVOCs-rich southerly air masses (13%). About 80% of sub-5 nm particle events led to the further growth. While high temperatures and high aerosol loadings in the southerly air masses were not favorable for nucleation, high BVOCs in the southerly air masses facilitated the growth of new particles to CCN-active sizes. In overall, 0.4-9.4% of the sub-5 nm particles grew to CCN-active sizes within each single NPF event. During a regional NPF event period that took place consecutively over several days, concentrations of CCN size particles increased by a factor of 4.7 in average. This enhanced production of CCN particles from new particles was commonly observed during all 13 regional NPF events during the campaign period. © 2014 American Association for Aerosol Research."
"32367837300;26867472700;56284582200;56726831900;7005446873;","Distinguishing the cold conveyor belt and sting jet airstreams in an intense extratropical cyclone",2014,"10.1175/MWR-D-13-00348.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84905715422&doi=10.1175%2fMWR-D-13-00348.1&partnerID=40&md5=968bbf5b0297d07ab8686d949abfb1cc","Strong winds equatorward and rearward of a cyclone core have often been associated with two phenomena: the cold conveyor belt (CCB) jet and sting jets. Here, detailed observations of the mesoscale structure in this region of an intense cyclone are analyzed. The in situ and dropsonde observations were obtained during two research flights through the cyclone during the Diabatic Influences on Mesoscale Structures in Extratropical Storms (DIAMET) field campaign. A numerical weather prediction model is used to link the strong wind regions with three types of ""airstreams"" or coherent ensembles of trajectories: two types are identified with the CCB, hooking around the cyclone center, while the third is identified with a sting jet, descending from the cloud head to the west of the cyclone. Chemical tracer observations show for the first time that the CCB and sting jet airstreams are distinct air masses even when the associated low-level wind maxima are not spatially distinct. In the model, the CCBexperiences slow latent heating through weak-resolved ascent and convection, while the sting jet experiences weak cooling associated with microphysics during its subsaturated descent. Diagnosis of mesoscale instabilities in the model shows that the CCB passes through largely stable regions, while the sting jet spends relatively long periods in locations characterized by conditional symmetric instability (CSI). The relation of CSI to the observed mesoscale structure of the bent-back front and its possible role in the cloud banding is discussed."
"7402934750;7003729315;6701806265;55619886800;","Aircraft evaluation of ground-based Raman lidar water vapor turbulence profiles in convective mixed layers",2014,"10.1175/JTECH-D-13-00075.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84901409768&doi=10.1175%2fJTECH-D-13-00075.1&partnerID=40&md5=fb776902b5f8226b6c0969dbe453f586","High temporal and vertical resolution water vapor measurements by Raman and differential absorption lidar systems have been used to characterize the turbulent fluctuations in the water vapor mixing ratio field in convective mixed layers. Since daytime Raman lidar measurements are inherently noisy (due to solar background and weak signal strengths), the analysis approach needs to quantify and remove the contribution of the instrument noise in order to derive the desired atmospheric water vapor mixing ratio variance and skewness profiles. This is done using the approach outlined by Lenschow et al.; however, an intercomparison with in situ observations was not performed. Water vapor measurements were made by a diode laser hygrometer flown on a Twin Otter aircraft during the Routine Atmospheric Radiation Measurement (ARM) Program Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign over the ARM Southern Great Plains (SGP) site in 2009. Two days with Twin Otter flights were identified where the convective mixed layer was quasi stationary, and hence the 10-s, 75-m data from the SGP Raman lidar could be analyzed to provide profiles of water vapor mixing ratio variance and skewness. Airborne water vapor observations measured during level flight legs were compared to the Raman lidar data, demonstrating good agreement in both variance and skewness. The results also illustrate the challenges of comparing a point sensor making measurements over time to a moving platform making similar measurements horizontally. © 2014 American Meteorological Society."
"56917398600;","A model-based approach to adjust microwave observations for operational applications: Results of a campaign at Munich Airport in winter 2011/2012",2013,"10.5194/amt-6-2879-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84887003599&doi=10.5194%2famt-6-2879-2013&partnerID=40&md5=9aa1a05db1e59b7e4fda71cb1fc925af","In the frame of the project ""LuFo iPort VIS"" which focuses on the implementation of a site-specific visibility forecast, a field campaign was organised to offer detailed information to a numerical fog model. As part of additional observing activities, a 22-channel microwave radiometer profiler (MWRP) was operating at the Munich Airport site in Germany from October 2011 to February 2012 in order to provide vertical temperature and humidity profiles as well as cloud liquid water information. Independently from the model-related aims of the campaign, the MWRP observations were used to study their capabilities to work in operational meteorological networks. Over the past decade a growing quantity of MWRP has been introduced and a user community (MWRnet) was established to encourage activities directed at the set up of an operational network. On that account, the comparability of observations from different network sites plays a fundamental role for any applications in climatology and numerical weather forecast. <br><br> In practice, however, systematic temperature and humidity differences (bias) between MWRP retrievals and co-located radiosonde profiles were observed and reported by several authors. This bias can be caused by instrumental offsets and by the absorption model used in the retrieval algorithms as well as by applying a non-representative training data set. At the Lindenberg observatory, besides a neural network provided by the manufacturer, a measurement-based regression method was developed to reduce the bias. These regression operators are calculated on the basis of coincident radiosonde observations and MWRP brightness temperature (TB) measurements. However, MWRP applications in a network require comparable results at just any site, even if no radiosondes are available. <br><br> The motivation of this work is directed to a verification of the suitability of the operational local forecast model COSMO-EU of the Deutscher Wetterdienst (DWD) for the calculation of model-based regression operators in order to provide unbiased vertical profiles during the campaign at Munich Airport. The results of this algorithm and the retrievals of a neural network, specially developed for the site, are compared with radiosondes from Oberschleißheim located about 10 km apart from the MWRP site. Outstanding deviations for the lowest levels between 50 and 100 m are discussed. Analogously to the airport experiment, a model-based regression operator was calculated for Lindenberg and compared with both radiosondes and operational results of observation-based methods. <br><br> The bias of the retrievals could be considerably reduced and the accuracy, which has been assessed for the airport site, is quite similar to those of the operational radiometer site at Lindenberg above 1 km height. Additional investigations are made to determine the length of the training period necessary for generating best estimates. Thereby three months have proven to be adequate. The results of the study show that on the basis of numerical weather prediction (NWP) model data, available everywhere at any time, the model-based regression method is capable of providing comparable results at a multitude of sites. Furthermore, the approach offers auspicious conditions for automation and continuous updating. © 2013 Author(s)."
"35731251200;7202429440;7201432984;7103183855;36551105100;7005451983;7005773698;","The impact of shipping, agricultural, and urban emissions on single particle chemistry observed aboard the R/V Atlantis during CalNex",2013,"10.1002/jgrd.50427","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84881190921&doi=10.1002%2fjgrd.50427&partnerID=40&md5=3051dd38e23e75df2a5ac4c5cd66d6d2","The Research at the Nexus of Air Quality and Climate Change (CalNex) field campaign was undertaken to obtain a better understanding of the regional impacts of different pollution sources in California. As part of this study, real-time shipboard measurements were made of the size-resolved, single-particle mixing state of submicron and supermicron particles (0.2-3.0 μm aerodynamic diameter) along the California coast where major differences were noted between Southern and Northern California. In Southern California, particles containing soot made up the largest fraction of submicron particles (~38% on average and up to ~89% by number), whereas organic carbon particles comprised the largest fraction of submicron number concentrations (~29% on average and up to ~78% by number) in Northern California including the Sacramento area. The mixing state of these carbonaceous particle types varied during the cruise with sulfate being more prevalent on soot-containing particles in Southern California due to the influence of fresh shipping and port emissions in addition to contributions from marine biogenic emissions. Contributions from secondary organic aerosol species, including amines, and nitrate were more prevalent in Northern California, as well as during time periods impacted by agricultural emissions (e.g., from the inland Riverside and Central Valley regions). These regional differences and changes in the mixing state and sources of particles have implications for heterogeneous reactivity, water uptake, and cloud-nucleating abilities for aerosols in California. Key PointsSouthern California was dominated by soot containing particlesNorthern California was dominated by organic carbon particlesParticle mixing-state was heavily influenced by meteorological conditions ©2013. American Geophysical Union. All Rights Reserved."
"9275665400;7402822814;","Simulation of particle formation and number concentration over the Eastern United States with the WRF-Chem + APM model",2011,"10.5194/acp-11-11521-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-81855172333&doi=10.5194%2facp-11-11521-2011&partnerID=40&md5=8a1e5d4df14efb1c2fcd3ebee63196c7","Aerosol nucleation events, widely observed at various locations around the globe, are a significant source of cloud condensation nuclei (CCN) which determines aerosol indirect radiative forcing. In this study, a size-resolved, computationally efficient, advanced particle microphysics (APM) model, which has been previously incorporated into a global chemistry transport model (GEOS-Chem), is integrated into the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) to study new particle formation and its contribution to particle number concentration and CCN abundance over the Eastern United States. Size-and composition-resolved aerosol properties from GEOS-Chem + APM simulations are used to initialize and provide boundary conditions for the WRF-Chem + APM model. The modeling results have been evaluated with the relevant measurements obtained during the INTEX-A field campaign in the summer of 2004. Model simulation captures the high concentrations of SO2 and CN10 at surface layer and source regions but underpredicts the values in the upper troposphere. The particle formation and number concentrations simulated by WRF-Chem + APM are generally consistent with those based on GEOS-Chem + APM over the Eastern United States, but the WRF-Chem + APM simulation has a much higher spatial resolution and can reveal urban and even plume scale processes. Our simulations show that high values of nucleation rates are largely confined to the regions of high SO2 emissions and that aerosol nucleation dominates the spatial and temporal distributions of condensation nuclei lager than 10 nm (CN10). Similarly, high concentrations of CCN at supersaturation of 0.4% (CCN0.4) are generally confined to SO2 source regions, with the highest monthly (July) mean CCN0.4 value exceeding 1600 # cm-3 in the lower troposphere over Indiana and Ohio. Nucleation and subsequent growth of secondary particles are important sources of CCN0.4, accounting for more than 80% in most parts of the Eastern United States. © 2011 Author(s)."
"57219425459;8522396600;55351772500;6701774423;7103333752;7102726801;","Energy balance in urban Mexico City: Observation and parameterization during the MILAGRO/MCMA-2006 field campaign",2011,"10.1007/s00704-010-0314-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79951811602&doi=10.1007%2fs00704-010-0314-7&partnerID=40&md5=9e2e1821f8632afbd8a0d5d9703796cc","The parameterization of the energy balance from a residential and commercial neighborhood of Mexico City was investigated using direct measurements of radiative and heat fluxes carried out during the MILAGRO/MCMA-2006 field campaign as a reference. The measured fluxes were used to evaluate different models of the energy balance based on parameterizations that require standard meteorological observations: ambient temperature, relative humidity, atmospheric pressure and cloudiness. It was found that these models reproduce with reasonable accuracy the diurnal features of the radiative and heat fluxes. The largest differences between modeled and observed fluxes correspond to the incoming longwave radiation, mainly due to errors in the cloudiness data. This paper contributes to the understanding of the energy partitioning in (sub)tropical urban environments, particularly in the developing world, where energy balance models have not been evaluated. © 2010 Springer-Verlag."
"35568218100;6603768446;","Influence of turbulence parameterizations on high-resolution numerical modeling of tropical convection observed during the TC4 field campaign",2010,"10.1029/2009JD013302","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956044593&doi=10.1029%2f2009JD013302&partnerID=40&md5=3b1b4fc61cb390832928a2ee33cb783a","In this work, deep moist convective processes, observed during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4) over the East Pacific Intertropical Convergence Zone, were modeled by means of high-resolution numerical simulations with the Weather Research and Forecasting model. Three different turbulence parameterizations and two microphysical parameterizations are used. Their impact on the spatio-temporal structure of predicted convective fields is compared to TC4 observations from a geostationary imager, airborne precipitation radar, and dropsondes. It is found that the large-eddy simulation turbulence closure ""upscaled"" to the terra incognita range of grid spacings (i.e., 0.1-1 km) is best suited to model the deep convective processes under examination. © Copyright 2010 by the American Geophysical Union."
"16443999400;56249792600;","ASTER- and field-based observations at Bezymianny Volcano: Focus on the 11 May 2007 pyroclastic flow deposit",2009,"10.1016/j.rse.2009.05.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67849128528&doi=10.1016%2fj.rse.2009.05.020&partnerID=40&md5=a138b70c69086588c24478ca90f782b2","Bezymianny (Kamchatka Peninsula, Russia) is an active stratovolcano, characterized by a summit lava dome and overlapping pyroclastic flow (PF) deposits to the southeast. Three explosive eruptions (24 December 2006, 11 May 2007, and 14 October 2007) generated PFs that were dominated by juvenile material and were emplaced primarily due to column collapse. Following this, a gravitational lava flow front collapse event generated block and ash flow on 5 November 2007. Moderate spatial resolution data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument were collected between October 2006 and December 2007 to assist in post-eruption monitoring and interpretation of the volcanological processes that produced the PF deposits. Using multitemporal ASTER thermal infrared (TIR) data, three periods of increased activity were observed that coincided with each eruption and subsequent activity. During a field campaign in August 2007, the May 2007 PF deposit was investigated in detail. Eight ASTER TIR pixels (90 m spatial resolution) were selected from the 30 June 2007 ASTER TIR image, seven of which were accessible in the field. Forward-Looking Infrared (FLIR) image and thermocouple data over these areas were collected to observe thermal heterogeneities with distance along the PF deposit. Although synchronous ASTER data were not possible at the time of fieldwork due to cloud cover, a field survey of blocks versus ash in each pixel was carried out to investigate thermal and textural variation with distance from the vent and to provide preliminary field results. Based on the field-derived temperature data and surface block percentages, the May 2007 PF deposit was more block-rich in the medial portion of the flow surface, but more ash-dominated at the PF terminus region, which promoted more rapid cooling. We present multitemporal ASTER data spanning a 14 month period and highlight ground-based observations acquired within the same period of eruptive and dome-growth activity. These data collectively provide thermal radiative and emissivity information on an actively changing explosive volcanic system and specifically documents changes over recently-emplaced and cooling PF deposits. © 2009 Elsevier Inc. All rights reserved."
"25722000200;6508333712;22633429500;56087850300;6602497877;57219982231;7003696133;26425254900;55339822300;16444503500;15069732800;35326039600;6701806265;","Observations of kinematics and thermodynamic structure surrounding a convective storm cluster over a low mountain range",2009,"10.1175/2008MWR2562.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-68249149271&doi=10.1175%2f2008MWR2562.1&partnerID=40&md5=a340881cbea4896ffa70cf458cf51481","Measurements of a convective storm cluster in the northern Black Forest in southwest Germany have revealed the development of a warm and dry downdraft under its anvil cloud that had an inhibiting effect on the subsequent development of convection. These measurements were made on 12 July 2006 as part of the field campaign Prediction, Identification and Tracking of Convective Cells (PRINCE) during which a number of new measurement strategies were deployed. These included the collocation of a rotational Raman lidar and a Doppler lidar on the summit of the highest mountain in the region (1164 m MSL) as well as the deployment of teams carrying radiosondes to be released in the vicinity of convective storms. In addition, an aircraft equipped with sensors for meteorological variables and dropsondes was in operation and determined that the downdraft air was approximately 1.5 K warmer, 4 g kg-1 drier, and therefore 3 g m-3 less dense than the air at the same altitude in the storm's surroundings. The Raman lidar detected undulating aerosol-rich layers in the preconvective environment and a gradual warming trend of the lower troposphere as the nearby storm system evolved. The Doppler lidar both detected a pattern of convergent radial winds under a developing convective updraft and an outflow emerging under the storm's anvil cloud. The dryness of the downdraft air indicates that it had subsided from higher altitudes. Its low density reveals that its development was not caused by negative thermal buoyancy, but was rather due to the vertical mass flux balance accompanying the storm's updrafts. © 2009 American Meteorological Society."
"6603431534;55740664200;55476479200;57198616562;8333586400;","Cloud, thermodynamic, and precipitation observations in West Africa during 2006",2009,"10.1029Z29/2008JD010641","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349311884&doi=10.1029Z29%2f2008JD010641&partnerID=40&md5=785739b46fe28c93a9f88bf41b02c71f","In 2006, the ARM Mobile Facility (AMF) completed a 1-year deployment at Niamey, Niger, Africa, in support of the Radiative Atmospheric Divergence using ARM Mobile Facility, GERB data and AMMA Stations (RADAGAST) field campaign, which is the subject of this special issue. Observations from the AMF instrumentation are used to analyze the relationship between clouds, precipitation, and the thermodynamic environment in this rarely observed region and to evaluate the cloud fields in the National Center for Environmental Prediction Global Forecast System (GFS) initialization product. The 1 -year deployment period enabled measurements in the dry and wet (monsoon) seasons and through the transitions in May and September, respectively. Cirrus clouds in the 10- to 15-km layer with modest monthly cloud fraction and mean depth of ~1 km are ubiquitous through the observing period as observed in other regions of the tropics. The monsoon season from May to September is characterized by convective clouds of varying depth that produce precipitation of varying intensity, as indicated by cloud radar. Peak surface rainfall is observed during August, and the largest daily rainfall rates are observed during the period from July to September. The lifting condensation level (LCL) is observed to decrease as the monsoon season progresses, and a strong correlation between the height of the LCL and precipitation is demonstrated. Cooling of the lower troposphere is implicated as the probable cause of the lowering of the LCL. Conversely, the amount of convective available potential energy is found to be poorly correlated with precipitation. As in other tropical regions, the physical height at which the zero-degree isotherm is observed corresponds to gradients in the thermodynamic profiles and a gradient in the profile of cloud occurrence. Comparisons with the GFS initialization data, which are derived from a number of sources including satellites, show some systematic biases when compared to AMF measurements. There is general correspondence between the locations of clouds and the profile of vertical velocity diagnosed by the GFS initialization early in the monsoon season, but vague correspondence thereafter. The relative humidity in the GFS initialization is too large above 10 km and too small in the monsoon layer near the surface, and it seriously underestimates the amount of cloud below 10 km during August, which is the height of the West African monsoon in Niamey. Copyright 2009 by the American Geophysical Union."
"8663598300;7004119542;7007061674;7202944988;7006212411;7201951829;57197256645;35595682100;8255698200;7201838864;7003529785;7406645661;7102011023;7402838215;","Supersaturations, microphysics and nitric acid partitioning in a cold cirrus cloud observed during CR-AVE 2006: An observation-modelling intercomparison study",2008,"10.1088/1748-9326/3/3/035003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-54749092131&doi=10.1088%2f1748-9326%2f3%2f3%2f035003&partnerID=40&md5=ed1462ee9ef032bfd85e89a1d5d6d89f","Supersaturations, microphysics and nitric acid partitioning in a very cold subvisible tropical cirrus cloud observed on 2 February 2006, during the field campaign CR-AVE, are studied by comparing a simulated set of possible cloud development scenarios with the in situ observations. The scenario that best matches the observations is a cirrus cloud forming by heterogeneous freezing of a small number of ice nuclei with subsequent unimpeded mass accommodation of water on ice. Variation of the freezing process, the accommodation coefficient or the amount of available water leads to simulated clouds that differ microphysically from the observed cloud in important respects. In particular, the simulations suggest that heterogeneous ice nucleation or another freezing mechanism producing only a low number of ice crystals could be an important process for cold cirrus cloud formation, possibly explaining the frequent observations of high supersaturations inside the cirrus cloud in this temperature regime. © 2008 IOP Publishing Ltd."
"7004585025;15130752900;56522444900;","Nocturnal stratiform cloudiness during the West African monsoon",2007,"10.1007/s00703-006-0194-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845266254&doi=10.1007%2fs00703-006-0194-7&partnerID=40&md5=db7a30a26e069e43cf79955f1d0775f0","An analysis of METEOSAT satellite images and synoptic reports from Parakou, Benin suggests that those nights that lack deep convection during the West African monsoon are often either completely clear or completely overcast at low levels. Using radiosonde observations gathered at Parakou during the IMPETUS field campaign of the summer of 2002 and ECMWF operational analyses, the composite structure of the atmosphere for both cloudy and clear nights is presented. Cloudy nights are found to occur when turbulent processes result in large-scale speed convergence in the boundary layer and a positive net moisture flux convergence. Conversely, the clear conditions occur when a nocturnal inversion decouples the boundary layer from the surface. The cloudy and clear conditions are also shown to be related to large-scale changes in the configurations of the African Easterly Jet and the Tropical Easterly Jet, although the nature of this relationship remains unclear. © Springer-Verlag 2006."
"7003708056;7003880283;36812255500;7006808794;15736673000;6507673679;6602922400;6701842515;7005228425;7004015298;7005198666;7007055581;7006354036;57195355942;6603081063;6601943623;","The Cloud Ice Mountain Experiment (CIME) 1998: Experiment overview and modelling of the microphysical processes during the seeding by isentropic gas expansion",2001,"10.1016/S0169-8095(01)00094-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034748028&doi=10.1016%2fS0169-8095%2801%2900094-1&partnerID=40&md5=6daa78e7f24d443b2a53601829609ab8","The second field campaign of the Cloud Ice Mountain Experiment (CIME) project took place in February 1998 on the mountain Puy de Dôme in the centre of France. The content of residual aerosol particles, of H2O2 and NH3 in cloud droplets was evaluated by evaporating the drops larger than 5 μm in a Counterflow Virtual Impactor (CVI) and by measuring the residual particle concentration and the released gas content. The same trace species were studied behind a round jet impactor for the complementary interstitial aerosol particles smaller than 5 μm diameter. In a second step of experiments, the ambient supercooled cloud was converted to a mixed phase cloud by seeding the cloud with ice particles by the gas release from pressurised gas bottles. A comparison between the physical and chemical characteristics of liquid drops and ice particles allows a study of the fate of the trace constituents during the presence of ice crystals in the cloud. In the present paper, an overview is given of the CIME 98 experiment and the instrumentation deployed. The meteorological situation during the experiment was analysed with the help of a cloud scale model. The microphysics processes and the behaviour of the scavenged aerosol particles before and during seeding are analysed with the detailed microphysical model ExMix. The simulation results agreed well with the observations and confirmed the assumption that the Bergeron-Findeisen process was dominating during seeding and was influencing the partitioning of aerosol particles between drops and ice crystals. The results of the CIME 98 experiment give an insight on microphysical changes, redistribution of aerosol particles and cloud chemistry during the Bergeron-Findeisen process when acting also in natural clouds. © 2001 Elsevier Science B.V. All rights reserved."
"56914807500;6701771206;7004289296;57199981887;7007019136;57217462176;57202460915;7103128133;7006549358;6701832375;","Case studies of the SO2 + H2O2 reaction in clouds",2000,"10.1029/1999jd901177","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033794474&doi=10.1029%2f1999jd901177&partnerID=40&md5=77b49ab299960bf131f52b4c55692f3a","The in-cloud reaction between SO2 and H2O2 has been investigated using data from field campaigns of July 1995 and July-August 1997 at Whiteface Mountain, New York. Cloud water samples were collected at the mountain's summit (1.5 km, above mean sea level (amsl)), and aerosols in clear air at a site (Lodge) located at 0.6 km amsl and in cloud interstitial air at the summit. Cloud water and aerosol samples were analyzed for SO42- and selected trace elements. Gaseous SO2 and H2O2 were measured at both sampling sites. Criteria based on total sulfur and O3 concentrations were developed to decide when the two sites were coupled (i.e., air masses at the two sites had the same composition for the chemical species studied). Four case studies are presented that exhibit varying concentration levels and different meteorological conditions. In two cases the sites were coupled, and in two others they were decoupled. The clouds showed high pollutant concentrations with a mean pH of 3.5. A tracer technique was used to quantitatively determine the SO42- produced from in situ SO2 oxidation. In general, good agreement between the SO2 consumed and SO42- produced was observed. Similarly, H2O2 concentrations in precloud air showed stoichiometric mass balance with the sum of H2O2 observed in cloud interstitial air, in cloud water, and equimolar amounts needed to produce SO4in2- as determined by the tracer technique. Data from all 24 clouds showed that (1) ∼28% of the cloud water SO42- was due to in situ oxidation; (2) ∼75% of the SO2 in the precloud air was oxidized in situ at Whiteface Mountain; (3) the mean SO2 concentration in air masses associated with cloudy periods is approximately 1.4 ppb, significantly higher than the summer average of 0.5 ppb; (4) the mean H2O2 concentration in cloud-free periods during summer is 1.1 ppb sufficient to oxidize SO2 present; (5) the frequent presence of H2O2 in cloud water indicated that the reaction had not often reached completion. Copyright 2000 by the American Geophysical Union."
"7005171879;7102910885;","Contrail properties derived from high-resolution polarization lidar studies during SUCCESS",1998,"10.1029/97GL03503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-14444286946&doi=10.1029%2f97GL03503&partnerID=40&md5=85229d4274c9571a0b1be0f26b1ac5ec","During April 1996 SUCCESS field campaign, our ground-based polarization lidar studied a variety of contrails ranging from a new NASA DC-8 contrail to persisting contrails from commercial jet aircraft that had spread into an almost invisible cirrostratus sheet. What distinguishes these contrails from natural cirrus is their tendency to remain thin (~50.500 m), and to generate strong laser backscattering and depolarizonation, often along with solar coronas, even an hour or more after formation. Lidar depolarization ratios in persisting contrails ranged from ~0.3-0.7. Contrial-cirrus clouds composed of high numbers of small (20-30 μm) particles would satisfy these findings, which has implications for comprehending their radiative and climatic effects.During the April 1996 SUCCESS field campaign, our ground-based polarization lidar studied a variety of contrails ranging from a new NASA DC-8 contrail to persisting contrails from commercial jet aircraft that had spread into an almost invisible cirrostratus sheet. What distinguishes these contrails from natural cirrus is their tendency to remain thin (approximately 50-500 m), and to generate strong laser backscattering and depolarization, often along with solar coronas, even an hour or more after formation. Lidar depolarization ratios in persisting contrails ranged from approximately 0.3-0.7. Contrail-cirrus clouds composed of high numbers of small (20-30 μm) particles would satisfy these findings, which has implications for comprehending their radiative and climatic effects."
"7101677832;35416153100;8723496500;7202185413;6602480054;7102063963;7101899854;","Retrieval of effective microphysical properties of clouds: a wave cloud case study",1998,"10.1029/98GL00042","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032522181&doi=10.1029%2f98GL00042&partnerID=40&md5=459d925d5ddde57e46e64559114f7eed","One of the important objectives of the SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) field campaign data analysis is to investigate retrieving cloud microphysical properties using remote sensing observations. This paper presents the results of an infrared based retrieval of effective particle radius Re using brightness temperature observations near 8.5, 11 and 12 μm. The retrieval method relies on comparing 8.5-11 and 11-12 μm observed brightness temperature differences to theoretical simulations. During SUCCESS, conducted in April-May 1996 out of Salina KS, the MODIS Airborne Simulator (MAS) on the NASA ER-2 made observations of contrails, cirrus and mountain lee wave clouds. Observations indicate that contrail and cirrus clouds are distinguishable by their radiative properties. Retrieval of Re for the lee wave cloud case on 2 May agrees with in situ observations from probes mounted on a NASA DC-8 aircraft, validating the infrared retrieval. The addition of the 8.5 μm information to the Re retrieval greatly enhances the sensitivity of the retrieval at small particle sizes (&lt;10 μm).One of the important objectives of the SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) field campaign data analysis is to investigate retrieving cloud microphysical properties using remote sensing observations. This paper presents the results of an infrared based retrieval of effective particle radius Re using brightness temperature observations near 8.5, 11 and 12 μm . The retrieval method relies on comparing 8.5-11 and 11-12 μm observed brightness temperature differences to theoretial simulations. During SUCCESS, conducted in April-May 1996 out of Salina KS, the MODIS Airborne Simulator (MAS) on the NASA ER-2 made observations of contrails, cirrus and mountain lee wave clouds. Observations indicate that contrail and cirrus clouds are distinguishable by their radiative properties. Retrieval of Re for the lee wave cloud case on 2 May agress with in situ observations from probes mounted on a NASA DC-8 aircraft, validating the infrared retrieval. The addition of the 8.5 μm information to the Re retrieval greatly enhances the sensitivity of the retrieval at small particles sizes (&lt;10 μm)."
"55940667800;7103016965;24764483400;55226243300;7801353107;18635820300;55838069100;7006728825;","Aerosol-cloud interactions in mixed-phase convective clouds - Part 1: Aerosol perturbations",2018,"10.5194/acp-18-3119-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043498589&doi=10.5194%2facp-18-3119-2018&partnerID=40&md5=f8914a4b7645cfa68873b8e32d2af370","Changes induced by perturbed aerosol conditions in moderately deep mixed-phase convective clouds (cloud top height ĝ1/4 g 5g km) developing along sea-breeze convergence lines are investigated with high-resolution numerical model simulations. The simulations utilise the newly developed Cloud-AeroSol Interacting Microphysics (CASIM) module for the Unified Model (UM), which allows for the representation of the two-way interaction between cloud and aerosol fields. Simulations are evaluated against observations collected during the COnvective Precipitation Experiment (COPE) field campaign over the southwestern peninsula of the UK in 2013. The simulations compare favourably with observed thermodynamic profiles, cloud base cloud droplet number concentrations (CDNC), cloud depth, and radar reflectivity statistics. Including the modification of aerosol fields by cloud microphysical processes improves the correspondence with observed CDNC values and spatial variability, but reduces the agreement with observations for average cloud size and cloud top height. <br><br> Accumulated precipitation is suppressed for higher-aerosol conditions before clouds become organised along the sea-breeze convergence lines. Changes in precipitation are smaller in simulations with aerosol processing. The precipitation suppression is due to less efficient precipitation production by warm-phase microphysics, consistent with parcel model predictions. <br><br> In contrast, after convective cells organise along the sea-breeze convergence zone, accumulated precipitation increases with aerosol concentrations. Condensate production increases with the aerosol concentrations due to higher vertical velocities in the convective cores and higher cloud top heights. However, for the highest-aerosol scenarios, no further increase in the condensate production occurs, as clouds grow into an upper-level stable layer. In these cases, the reduced precipitation efficiency (PE) dominates the precipitation response and no further precipitation enhancement occurs. Previous studies of deep convective clouds have related larger vertical velocities under high-aerosol conditions to enhanced latent heating from freezing. In the presented simulations changes in latent heating above the 0°C are negligible, but latent heating from condensation increases with aerosol concentrations. It is hypothesised that this increase is related to changes in the cloud field structure reducing the mixing of environmental air into the convective core. <br><br> The precipitation response of the deeper mixed-phase clouds along well-established convergence lines can be the opposite of predictions from parcel models. This occurs when clouds interact with a pre-existing thermodynamic environment and cloud field structural changes occur that are not captured by simple parcel model approaches. © Author(s) 2018."
"57201284843;56779721100;57186194700;25929453700;55949126400;","Drone-borne hyperspectral monitoring of acid mine drainage: An example from the Sokolov lignite district",2018,"10.3390/rs10030385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044218149&doi=10.3390%2frs10030385&partnerID=40&md5=36ceabeb1efd523155196f5419bc7c07","This contribution explores the potential of unmanned aerial systems (UAS) to monitor areas affected by acid mine drainage (AMD). AMD is an environmental phenomenon that usually develops in the vicinity of mining operations or in post-mining landscapes. The investigated area covers a re-cultivated tailing in the Sokolov lignite district of the Czech Republic. A high abundance of AMD minerals occurs in a confined space of the selected test site and illustrates potential environmental issues. The mine waste material contains pyrite and its consecutive weathering products, mainly iron hydroxides and oxides. These affect the natural pH values of the Earth's surface. Prior research done in this area relies on satellite and airborne data, and our approach focuses on lightweight drone systems that enables rapid deployment for field campaigns and consequently-repeated surveys. High spatial image resolutions and precise target determination are additional advantages. Four field and flight campaigns were conducted from April to September 2016. For validation, the waste heap was probed in situ for pH, X-ray fluorescence (XRF), and reflectance spectrometry. Ground truth was achieved by collecting samples that were characterized for pH, X-ray diffraction, and XRF in laboratory conditions. Hyperspectral data were processed and corrected for atmospheric, topographic, and illumination effects using accurate digital elevation models (DEMs). High-resolution point clouds and DEMs were built from drone-borne RGB data using structure-from-motion multi-view-stereo photogrammetry. The supervised classification of hyperspectral image (HSI) data suggests the presence of jarosite and goethite minerals associated with the acidic environmental conditions (pH range 2.3-2.8 in situ). We identified specific iron absorption bands in the UAS-HSI data. These features were confirmed by ground-truth spectroscopy. The distribution of in situ pH data validates the UAS-based mineral classification results. Evaluation of the applied methods demonstrates that drone surveying is a fast, non-invasive, inexpensive technique for multi-temporal environmental monitoring of post-mining landscapes. © 2018 by the authors."
"57194491444;7005304841;56153039700;24472110700;7003875148;24398842400;","Modelling micro- and macrophysical contributors to the dissipation of an Arctic mixed-phase cloud during the Arctic Summer Cloud Ocean Study (ASCOS)",2017,"10.5194/acp-17-6693-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020479765&doi=10.5194%2facp-17-6693-2017&partnerID=40&md5=add328872f0a040f4336dd470be21c2b","The Arctic climate is changing; temperature changes in the Arctic are greater than at midlatitudes, and changing atmospheric conditions influence Arctic mixed-phase clouds, which are important for the Arctic surface energy budget. These low-level clouds are frequently observed across the Arctic. They impact the turbulent and radiative heating of the open water, snow, and sea-ice-covered surfaces and influence the boundary layer structure. Therefore the processes that affect mixed-phase cloud life cycles are extremely important, yet relatively poorly understood. In this study, we present sensitivity studies using semi-idealized large eddy simulations (LESs) to identify processes contributing to the dissipation of Arctic mixed-phase clouds. We found that one potential main contributor to the dissipation of an observed Arctic mixed-phase cloud, during the Arctic Summer Cloud Ocean Study (ASCOS) field campaign, was a low cloud droplet number concentration (CDNC) of about 2ĝ€ cmĝ '3. Introducing a high ice crystal concentration of 10ĝ€ Lĝ '1 also resulted in cloud dissipation, but such high ice crystal concentrations were deemed unlikely for the present case. Sensitivity studies simulating the advection of dry air above the boundary layer inversion, as well as a modest increase in ice crystal concentration of 1ĝ€ Lĝ'1, did not lead to cloud dissipation. As a requirement for small droplet numbers, pristine aerosol conditions in the Arctic environment are therefore considered an important factor determining the lifetime of Arctic mixed-phase clouds. © Author(s) 2017."
"57210590791;7403331283;7801634218;7006728825;8724962900;7006861480;35219670500;14044750400;7006377579;7201572145;55454856700;35387836300;7006235542;7402579146;57201806565;21933618400;13403627400;56412394000;56888739700;57197495727;7201787800;57195257572;12800536400;24802274700;55838457400;37026251000;7202970215;16477177600;35572096100;36941730100;56906459000;9536598800;57190005849;7004860305;7101691582;35330541400;7404021119;23486614500;7202129754;55226243300;14819962800;55783064400;55427215500;37089603000;57188742108;","The Convective Precipitation Experiment (COPE): Investigating the origins of heavy precipitation in the southwestern United Kingdom",2016,"10.1175/BAMS-D-14-00157.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978128450&doi=10.1175%2fBAMS-D-14-00157.1&partnerID=40&md5=f1324ddb88d99510ef2c4e9323ea7796","The Convective Precipitation Experiment (COPE) was a joint U.K.-U.S. field campaign held during the summer of 2013 in the southwest peninsula of England, designed to study convective clouds that produce heavy rain leading to flash floods. The clouds form along convergence lines that develop regularly as a result of the topography. Major flash floods have occurred in the past, most famously at Boscastle in 2004. It has been suggested that much of the rain was produced by warm rain processes, similar to some flash floods that have occurred in the United States. The overarching goal of COPE is to improve quantitative convective precipitation forecasting by understanding the interactions of the cloud microphysics and dynamics and thereby to improve numerical weather prediction (NWP) model skill for forecasts of flash floods. Two research aircraft, the University of Wyoming King Air and the U.K. BAe 146, obtained detailed in situ and remote sensing measurements in, around, and below storms on several days. A new fast-scanning X-band dual-polarization Doppler radar made 360° volume scans over 10 elevation angles approximately every 5 min and was augmented by two Met Office C-band radars and the Chilbolton S-band radar. Detailed aerosol measurements were made on the aircraft and on the ground. This paper i) provides an overview of the COPE field campaign and the resulting dataset, ii) presents examples of heavy convective rainfall in clouds containing ice and also in relatively shallow clouds through the warm rain process alone, and iii) explains how COPE data will be used to improve high-resolution NWP models for operational use. ©2016 American Meteorological Society."
"55192470800;37099534700;57204252724;57148462400;55588368000;23995341000;7004210193;6507703419;54409650800;6701773543;55053339600;56500318900;6603745877;7003478309;56560167400;7004607037;","A comparative study of aerosol microphysical properties retrieved from ground-based remote sensing and aircraft in situ measurements during a Saharan dust event",2016,"10.5194/amt-9-1113-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961774517&doi=10.5194%2famt-9-1113-2016&partnerID=40&md5=2c0c3fe8d64dc1f2d3a0e3a6eb0200d0","In this work we present an analysis of aerosol microphysical properties during a mineral dust event taking advantage of the combination of different state-of-the-art retrieval techniques applied to active and passive remote sensing measurements and the evaluation of some of those techniques using independent data acquired from in situ aircraft measurements. Data were collected in a field campaign performed during a mineral dust outbreak at the Granada, Spain, experimental site (37.16° N, 3.61° W, 680 m a.s.l.) on 27 June 2011. Column-integrated properties are provided by sun- and star-photometry, which allows for a continuous evaluation of the mineral dust optical properties during both day and nighttime. Both the linear estimation and AERONET (Aerosol Robotic Network) inversion algorithms are applied for the retrieval of the column-integrated microphysical particle properties. In addition, vertically resolved microphysical properties are obtained from a multi-wavelength Raman lidar system included in EARLINET (European Aerosol Research Lidar Network), by using both LIRIC (Lidar Radiometer Inversion Code) algorithm during daytime and an algorithm applied to the Raman measurements based on the regularization technique during nighttime. LIRIC retrievals reveal the presence of dust layers between 3 and 5 km a.s.l. with volume concentrations of the coarse spheroid mode up to 60 μm3 cm-3. The combined use of the regularization and LIRIC methods reveals the night-to-day evolution of the vertical structure of the mineral dust microphysical properties and offers complementary information to that from column-integrated variables retrieved from passive remote sensing. Additionally, lidar depolarization profiles and LIRIC retrieved volume concentration are compared with aircraft in situ measurements. This study presents for the first time a comparison of the total volume concentration retrieved with LIRIC with independent in situ measurements, obtaining agreement within the estimated uncertainties for both methods and quite good agreement for the vertical distribution of the aerosol layers. Regarding the depolarization, the first published data set of the CAS-POL for polarization ratios is presented here and qualitatively compared with the lidar technique. © Author(s) 2016."
"22935673400;6602999057;9536598800;6603327055;12042447700;","Modeling haboob dust storms in large-scale weather and climate models",2016,"10.1002/2015JD024349","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959520243&doi=10.1002%2f2015JD024349&partnerID=40&md5=2fced5b0c274d6579458e486f84a47dd","Recent field campaigns have shown that haboob dust storms, formed by convective cold pool outflows, contribute a significant fraction of dust uplift over the Sahara and Sahel in summer. However, in situ observations are sparse and haboobs are frequently concealed by clouds in satellite imagery. Furthermore, most large-scale weather and climate models lack haboobs, because they do not explicitly represent convection. Here a 1 year long model run with explicit representation of convection delivers the first full seasonal cycle of haboobs over northern Africa. Using conservative estimates, the model suggests that haboobs contribute one fifth of the annual dust-generating winds over northern Africa, one fourth between May and October, and one third over the western Sahel during this season. A simple parameterization of haboobs has recently been developed for models with parameterized convection, based on the downdraft mass flux of convection schemes. It is applied here to two model runs with different horizontal resolutions and assessed against the explicit run. The parameterization succeeds in capturing the geographical distribution of haboobs and their seasonal cycle over the Sahara and Sahel. It can be tuned to the different horizontal resolutions, and different formulations are discussed with respect to the frequency of extreme events. The results show that the parameterization is reliable and may solve a major and long-standing issue in simulating dust storms in large-scale weather and climate models. ©2016. American Geophysical Union. All Rights Reserved."
"35768617200;6603562975;7005126327;7102581856;6505732261;57191330729;6701772538;8719703500;7006717176;7004678728;","In situ and space-based observations of the Kelud volcanic plume: The persistence of ash in the lower stratosphere",2016,"10.1002/2016JD025344","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988847810&doi=10.1002%2f2016JD025344&partnerID=40&md5=517035677cf6311224b75af343205388","Volcanic eruptions are important causes of natural variability in the climate system at all time scales. Assessments of the climate impact of volcanic eruptions by climate models almost universally assume that sulfate aerosol is the only radiatively active volcanic material. We report satellite observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite after the eruption of Mount Kelud (Indonesia) on 13 February 2014 of volcanic materials in the lower stratosphere. Using these observations along with in situ measurements with the Compact Optical Backscatter AerosoL Detector (COBALD) backscatter sondes and optical particle counters (OPCs) made during a balloon field campaign in northern Australia, we find that fine ash particles with a radius below 0.3 μm likely represented between 20 and 28% of the total volcanic cloud aerosol optical depth 3 months after the eruption. A separation of 1.5–2 km between the ash and sulfate plumes is observed in the CALIOP extinction profiles as well as in the aerosol number concentration measurements of the OPC after 3 months. The settling velocity of fine ash with a radius of 0.3 μm in the tropical lower stratosphere is reduced by 50% due to the upward motion of the Brewer-Dobson circulation resulting a doubling of its lifetime. Three months after the eruption, we find a mean tropical clear-sky radiative forcing at the top of the atmosphere from the Kelud plume near 0.08 W/m2 after including the presence of ash; a value ~20% higher than if sulfate alone is considered. Thus, surface cooling following volcanic eruptions could be affected by the persistence of ash and should be considered in climate simulations. © 2016. The Authors."
"57198616562;37018824600;8333586400;7004369046;6603357893;56495509000;56494529800;9132948500;7401936984;","The Midlatitude Continental Convective Clouds Experiment (MC3E) sounding network: Operations, processing and analysis",2015,"10.5194/amt-8-421-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921763375&doi=10.5194%2famt-8-421-2015&partnerID=40&md5=5beb61fce9085d8a0a8bf0bcc69a59aa","The Midlatitude Continental Convective Clouds Experiment (MC3E) took place during the spring of 2011 centered in north-central Oklahoma, USA. The main goal of this field campaign was to capture the dynamical and microphysical characteristics of precipitating convective systems in the US Central Plains. A major component of the campaign was a six-site radiosonde array designed to capture the large-scale variability of the atmospheric state with the intent of deriving model forcing data sets. Over the course of the 46-day MC3E campaign, a total of 1362 radiosondes were launched from the enhanced sonde network. This manuscript provides details on the instrumentation used as part of the sounding array, the data processing activities including quality checks and humidity bias corrections and an analysis of the impacts of bias correction and algorithm assumptions on the determination of convective levels and indices. It is found that corrections for known radiosonde humidity biases and assumptions regarding the characteristics of the surface convective parcel result in significant differences in the derived values of convective levels and indices in many soundings. In addition, the impact of including the humidity corrections and quality controls on the thermodynamic profiles that are used in the derivation of a large-scale model forcing data set are investigated. The results show a significant impact on the derived large-scale vertical velocity field illustrating the importance of addressing these humidity biases. © 2015 Author(s)."
"35319691100;7407084420;7102949463;","The kinematic and microphysical characteristics and associated precipitation efficiency of subtropical convection during SoWMEX/TiMREX",2015,"10.1175/MWR-D-14-00081.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921453674&doi=10.1175%2fMWR-D-14-00081.1&partnerID=40&md5=c8f5f112d453eecf66c9c54b4aa1ceff","Dual-Doppler, polarimetric radar observations and precipitation efficiency (PE) calculations are used to analyze subtropical heavy rainfall events that occurred in southern Taiwan from 14 to 17 June 2008 during the Southwest Monsoon Experiment/Terrain-Influenced Monsoon Rainfall Experiment (SoWMEX/TiMREX) field campaign. Two different periods of distinct precipitation systems with diverse kinematic and microphysical characteristics were investigated: 1) prefrontal squall line (PFSL) and 2) southwesterly monsoon mesoscale convective system (SWMCS). The PFSL was accompanied by a low-level front-to-rear inflow and pronounced vertical wind shear. In contrast, the SWMCS had a low-level southwesterly rear-to-front flow with a uniform vertical wind field. The PFSL (SWMCS) contained high (low) lightning frequency associated with strong (moderate) updrafts and intense graupel-rain/graupel-small hail mixing (more snow and less graupel water content) above the freezing level. It is postulated that the reduced vertical wind shear and enhanced accretional growth of rain by high liquid water content at low levels in the SWMCS helped produce rainfall more efficiently (53.1%). On the contrary, the deeper convection of the PFSL had lower PE (45.0%) associated with the evaporative loss of rain and the upstream transport of liquid water to form larger stratiform regions. By studying these two events, the dependence of PE on the environmental and microphysical factors of subtropical heavy precipitation systems are investigated by observational data for the first time. Overall, the PE of the convective precipitation region (47.9%) from 14 to 17 June is similar to past studies of convective precipitation in tropical regions. © 2015 American Meteorological Society."
"23065650200;55463274000;55663817800;","Representing the ice fall speed in climate models: Results from Tropical Composition, Cloud and Climate Coupling (TC4) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC)",2011,"10.1029/2010JD015433","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80053067481&doi=10.1029%2f2010JD015433&partnerID=40&md5=2bc3e3ff854933d5384afcca0859b985","Ice fall velocity has a strong impact on climate feedback, influencing cirrus cloud coverage and radiative forcing as well as upper troposphere relative humidity. This study aims to provide the atmospheric modeling community with better parameterizations of the ice fall speed in cirrus clouds on the basis of aircraft measurements from recent field campaigns, especially the Tropical Composition, Cloud and Climate Coupling (TC4) campaign in 2007 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. These campaigns provide improved measurements of the ice particle size distribution (PSD) where the concentrations of artifact small ice particles (due to shattering of ice particles on the probe inlet tube) are greatly reduced. In addition to the PSD, the mass-weighted fall velocity (V<inf>m</inf>) depends on the ice particle projected area and mass. The calculation of V<inf>m</inf> was based on improved direct measurements of the PSD number and area concentration and improved estimates of ice particle mass. The effective diameter (D<inf>e</inf>) was calculated in a similar way. The TC4 analysis has provided a diagnostic relationship that relates V<inf>m</inf> to both cloud temperature (T) and ice water content (IWC) with an r2 of 0.78. A similar relationship for D<inf>e</inf> was also obtained with an r2 of 0.82. The V<inf>m</inf> relationship and associated V<inf>m</inf>-IWC-T measurements were found to agree well with a V<inf>m</inf> scheme based on T and cloud radar retrievals of V<inf>m</inf> and IWC in tropical cirrus clouds. However, a critical climate-influencing parameter like the ice fall speed needs to be coupled with the cloud microphysics and radiation in climate models. This is made possible through strong correlations between D<inf>e</inf> and V<inf>m</inf> regarding TC4 and ISDAC cirrus. Finally, TC4 satellite retrievals of D<inf>e</inf> and V<inf>m</inf> are found to be consistent with corresponding observations. Copyright 2011 by the American Geophysical Union."
"25521967600;7005955015;6603400151;6506763515;8061325100;57195139224;","The full life cycle of a polar low over the Norwegian Sea observed by three research aircraft flights",2011,"10.1002/qj.825","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052543811&doi=10.1002%2fqj.825&partnerID=40&md5=ffbab2e4cb7073315353819afc30ddc5","During 3-4 March 2008, the Norwegian IPY-THORPEX field campaign successfully carried out three flight missions that observed the full life cycle of a polar low over the Norwegian Sea. Here the three-dimensional structure of the polar low has been investigated using dropsonde data from the three flights. The polar low developed in a cold air outbreak, with temperature differences between the sea surface and 500 hPa of about 45-50°C. Cross-sections show that the horizontal gradients of potential temperature weakened as the polar low matured, suggesting that baroclinic energy conversion took place. Dropsonde data of potential temperature and relative humidity show evidence of a tropopause fold, which is possibly a manifestation of upper-level forcing. This is corroborated by potential vorticity inversion, which shows a dominant role of upper-level forcing throughout the polar low's lifetime. During the cyclogenesis stage the polar low circulation was confined below 700 hPa, with a northerly low-level jet of 26 m s-1. In the mature stage, its circulation reached up to the tropopause (∼450 hPa), with maximum wind speed between 700 and 900 hPa of about 26-28 m s-1. At this stage the polar low warm core was about 3 K warmer than surrounding air masses. The deep moist towers at the eye-like structure of the polar low extended up to the tropopause with relative humidity values above 70%, indicating a possibly important role for condensational heating in the development. Estimates of surface fluxes of sensible and latent heat using temperature and moisture from the dropsonde data show latent heat fluxes west of the polar low increasing from 175 to 300 W m-2 as the low matured, while the sensible heat fluxes rose from 200 to 280 W m-2, suggesting a gradually increasing contribution of surface fluxes to the energetics of the polar low with time. © 2011 Royal Meteorological Society."
"8600097900;15032788000;","Identification of small ice cloud particles using passive radiometric observations",2010,"10.1175/2010JAMC2466.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78149386263&doi=10.1175%2f2010JAMC2466.1&partnerID=40&md5=cb6a015c05bbfc15791675dc5c2e02b3","There is currently significant uncertainty about the extent to which cirrus clouds are composed of ""small"" ice crystals smaller than about 20-mmeffective radius. This is due in part to concerns that in situ measurements from aircraft are plagued by ice particle shattering on instrument inlets, artificially negatively biasing effective radii. Here, space-based measurements are applied to the problem. It is found that a space-based infrared split-window technique is less sensitive but more accurate than a visible-near-infrared technique for confident assessment of whether thin cirrus clouds have small effective radii, independent of a normal range of retrieval assumptions. Because of the sensitivities of the infrared split-window technique, however, this method can only accurately determine the presence of small particles for ice clouds with optical depths between roughly 0.5 and 3.0. Applied to Moderate Resolution Imaging Spectroradiometer (MODIS) data, it is found that a very conservative minimum of 15%-20% of such thin cirrus globally are composed of small ice crystals, but that the actual value could be as high as 40%, and even higher for cold clouds or those in the tropics. Retrievals are found to be in good agreement with airborne probe measurements from the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida-Area Cirrus Experiment (CRYSTAL-FACE) field campaign, implying that, for the cases examined, the impact of inlet shattering on measurements must have been limited. © 2010 American Meteorological Society."
"56888458200;6701530932;","Near-surface fluxes of cloud water evolve vertically",1999,"10.1256/smsqj.55915","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033377784&doi=10.1256%2fsmsqj.55915&partnerID=40&md5=68bcbbe72b2031a65a77d2993b786906","Occult deposition to vegetation, via mechanical interception of wind-blown cloud water, can be a significant fraction of total ionic chemical deposition for some forests. Applying micrometeorological methods to the estimation of cloud water deposition requires particular consideration since cloud droplets are not conservative but are subject to material change (phase change); sedimentation also affects fluxes of droplets. The budget equation for liquid water (LW) in orographic cloud predicts that LW fluxes will diverge due to condensation during mean ascent. For hilltop measurements such as these, other factors can contribute to changes in the vertical flux with height above the surface. Fluxes measured concurrently at two heights exhibit a persistent and significant divergence, while laterally separated measurements are found to agree. A LW budget equation is presented and simplified by scale analysis. Surface uptake is estimated by extrapolation of the measured fluxes. Estimated surface deposition is found to be substantially different from the flux measured at a reference height (10 m), often by a factor of two and occasionally with a different sign. This difference in estimated surface uptake extends to estimates of chemical as well as water deposition. The turbulent flux of LW is shown to be dependent on two criteria for describing 'steady-cloud' conditions, thus presumably minimizing the effects of entrainment. An often used model relating droplet deposition to the 'deposition velocity' for momentum is found to be inappropriate for application in complex terrain. Deposition of LW is estimated to range from 5 to 50 mg m-2 s-1 during the third field campaign of the Cloud and Aerosol CHemistry Experiment (CACHE-3), with an average of 19 mg m-2s-1 (nearly 2 mm per in-cloud day) in late summer at this Pacific coastal site in North America."
"16170561000;7003708056;7003880283;7006377579;7005088845;7006595513;7102496779;7005174340;35477504600;6701336868;7004015298;7005601996;7006354036;7003640784;","Microphysics of clouds: Model vs measurements",1997,"10.1016/S1352-2310(97)00041-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030616215&doi=10.1016%2fS1352-2310%2897%2900041-1&partnerID=40&md5=c8e6d481011280befdbcc1fdb4fb4de9","In order to study the relation between the initial aerosol particle spectrum at cloud base and the resulting droplet spectrum in cloud for the 'Ground-based Cloud Experiment' field campaign at the Great Dun Fell in 1993 numerical model simulations have been performed. The droplet spectra were calculated from a microphysical model coupled to a dynamic air flow model. The resulting droplet spectra were compared with cloud droplet spectra measured with a forward scattering spectrometer probe. The size distribution and chemical composition of the initial aerosol population were derived from a combination of size distribution and size-segregated chemical measurements below cloud base. From this we concluded that the aerosol particles consisted almost entirely of an inorganic salt. As part of the sensitivity studies two different microphysical models were used, as well as the dynamic flow fields from two different air flow models. As in previous studies we found that the measured droplet spectra were broader and contained larger drops than the modelled spectra. From the sensitivity studies we identified fluctuations in the dynamics as the most likely explanation for these differences."
"6603569074;7102892446;6603954927;57216589427;","Observations of spatial variations of boundary layer structure over the southern great plains cloud and radiation testbed",1997,"10.1175/1520-0450(1997)036<1221:OOSVOB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031402383&doi=10.1175%2f1520-0450%281997%29036%3c1221%3aOOSVOB%3e2.0.CO%3b2&partnerID=40&md5=63a0d577bf5872b55f85e698b9236fd4","Results from a field campaign to study the response of the planetary boundary layer to spatially varying surface conditions are presented. Radiosondes released at four locations with contrasting land use characteristics in the U.S. Department of Energy's Cloud and Radiation Testbed (CART) in Kansas and Oklahoma showed significant variations in mixed-layer depth, temperature, and water vapor mixing ratios over distances of 100-200 km. Using CART and radiosonde data, estimates of the surface sensible and latent heat fluxes are derived; the results from several methods are compared and a discussion of the similarities and differences in the values is given. Although substantial flux differences among the sites account for some of the variations in the boundary layer behavior, other features of the ambient meteorology and initial conditions appear to be equally important. Despite large changes in mixed-layer and surface-layer temperatures over scales of approximately 100 km, no evidence for temperature-induced secondary circulations was found. A simple scaling argument is presented that gives a possible reason for this absence."
"55798292600;23491866500;53986467700;9739197000;7003460110;","Regional scale mapping of grassland mowing frequency with Sentinel-2 time series",2018,"10.3390/rs10081221","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051644756&doi=10.3390%2frs10081221&partnerID=40&md5=48f06230d86f44ee4d3ca522fd65e9f2","Grassland use intensity is a topic of growing interest worldwide, as grasslands are integral in supporting biodiversity, food production, and regulating of the global carbon cycle. Data available for characterizing grasslands management are largely descriptive and collected from laborious field campaigns or questionnaires. The recent launch of the Sentinel-2 earth monitoring constellation provides new possibilities for high temporal and spatial resolution remote sensing data covering large areas. This study aims to evaluate the potential of a time series of Sentinel-2 data for mapping of mowing frequency in the region of Canton Aargau, Switzerland. We tested two cloud masking processes and three spatial mapping units (pixels, parcel polygons and shrunken parcel polygons), and investigated how missing data influence the ability to accurately detect and map grassland management activity. We found that more than 40% of the study area was mown before 15 June, while the remaining part was either mown later, or was not mown at all. The highest accuracy for detection of mowing events was achieved using additional clouds masking and size reduction of parcels, which allowed correct detection of 77% of mowing events. Additionally, we found that using only standard cloud masking leads to significant overestimation of mowing events, and that the detection based on sparse time series does not fully correspond to key events in the grass growth season. © 2018 by the authors."
"57191245936;6602453684;57188574592;57200992844;55950438300;55675557500;57200990398;","Campo Verde Database: Seeking to Improve Agricultural Remote Sensing of Tropical Areas",2018,"10.1109/LGRS.2017.2789120","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040918861&doi=10.1109%2fLGRS.2017.2789120&partnerID=40&md5=94ac7990d8db8dee9e8e1ee642bb7b48","In tropical/subtropical regions, the favorable climate associated with the use of agricultural technologies, such as no tillage, minimum cultivation, irrigation, early varieties, desiccants, flowering inducing, and crop rotation, makes agriculture highly dynamic. In this letter, we present the Campo Verde agricultural database. The purpose of creating and sharing these data is to foster advancement of remote sensing technology in areas of tropical agriculture, primarily the development and testing of methods for crop recognition and agricultural mapping. Campo Verde is a municipality of Mato Grosso state, localized in the Cerrado (Brazilian Savanna) biome, in central west Brazil. Soybean, maize, and cotton are the primary crops cultivated in this region. Double cropping systems are widely adopted in this area. There is also livestock and forestry production. Our database provides the land-use classes for 513 fields by month for one Brazilian crop year (between October 2015 and July 2016). This information was gathered during two field campaigns in Campo Verde (December 2015 and May 2016) and by visual interpretation of a time series of Landsat-8/Operational Land Imager (OLI) images using an experienced interpreter. A set of 14 preprocessed synthetic aperture radar Sentinel-1 and 15 Landsat-8/OLI mosaic images is also made available. It is important to promote the use of radar data for tropical agricultural applications, especially because the use of optical remote sensing in these regions is hindered by the high frequency of cloud cover. To demonstrate the utility of our database, results of an experiment conducted using the Sentinel-1 data set are presented. © 2004-2012 IEEE."
"37099564300;34881780600;6506328135;57193213111;7102866124;57189372185;","Spatial variability of the background diurnal cycle of deep convection around the GoAmazon2014/5 field campaign sites",2016,"10.1175/JAMC-D-15-0229.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996504190&doi=10.1175%2fJAMC-D-15-0229.1&partnerID=40&md5=5fcace04a599e3d3899a1f1cfb5c5c86","The isolation of the Amazon rain forest makes it challenging to observe precipitation forming there, but it also creates a natural laboratory to study anthropogenic impacts on clouds and precipitation in an otherwise pristine environment. Observations were collected upwind and downwind of Manaus, Brazil, during the ""Observations and Modeling of the Green Ocean Amazon 2014-2015"" experiment (GoAmazon2014/5). Besides aircraft, most of the observations were point measurements made in a spatially heterogeneous environment, making it hard to distinguish anthropogenic signals from naturally occurring spatial variability. In this study, 15 years of satellite data are used to examine the spatial and temporal variability of deep convection around the GoAmazon2014/5 sites using cold cloud tops (infrared brightness temperatures colder than 240 K) as a proxy for deep convection. During the rainy season, convection associated with the inland propagation of the previous day's sea-breeze front is in phase with the diurnal cycle of deep convection near Manaus but is out of phase a few hundred kilometers to the east and west. Convergence between the river breezes and the easterly trade winds generates afternoon convection up to 10% more frequently (on average ~4 mm day-1 more intense rainfall) at the GoAmazon2014/5 sites east of the Negro River (T0e, T0t/k, and T1) relative to the T3 site, which was located west of the river. In general, the annual and diurnal cycles of precipitation during 2014 were similar to climatological values that are based on satellite data from 2000 to 2013. © 2016 American Meteorological Society."
"35494005000;57188863155;8600097900;12645767500;6603768446;37111931100;","Retrieving co-occurring cloud and precipitation properties of warm marine boundary layer clouds with A-train data",2016,"10.1002/2015JD023681","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963946884&doi=10.1002%2f2015JD023681&partnerID=40&md5=39356e4a66c4f7548d7deff1d8705cff","In marine boundary layer (MBL) clouds the formation of precipitation from the cloud droplet distribution in the presence of variable aerosol plays a fundamental role in determining the coupling of these clouds to their environment and ultimately to the climate system. Here the degree to which A-Train satellite measurements can diagnose simultaneously occurring cloud and precipitation properties in MBL clouds is examined. Beginning with the measurements provided by CloudSat and Moderate Resolution Imaging Spectroradiometer (including a newly available microwave brightness temperature from CloudSat), and a climatology of MBL cloud properties from past field campaigns, an assumption is made that any hydrometeor volume could contain both cloud droplet and precipitation droplet modes. Bayesian optimal estimation is then used to derive atmospheric states by inverting ameasurement vector carefully accounting for uncertainties due to instrument noise, forward model error, and assumptions. It is found that in many cases where significant precipitation coexists with cloud, due to forward model error driven by uncertainties in assumptions, the uncertainty in retrieved cloud properties is greater than the variance in the prior climatology. It is often necessary to average several thousand (hundred) precipitating (weakly precipitating) profiles to obtain meaningful information regarding the properties important to microphysical processes. Regardless, if such process level information is deemed necessary for better constraining predictive models of the climate system, measurement systems specifically designed to accomplish such retrievals must be considered for the future. © 2016. American Geophysical Union. All Rights Reserved."
"56229926400;57204253860;9635764200;","Radar observations of MJO and Kelvin wave interactions during DYNAMO/ CINDY2011/AMIE",2014,"10.1002/2013JD021031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84903287579&doi=10.1002%2f2013JD021031&partnerID=40&md5=f3646759172e9f062c661de2ff43ce15","Radar and sounding data collected during the Dynamics of the Madden-Julian Oscillation (DYNAMO), the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY2011), and the Atmospheric Radiation Measurement (ARM) Madden-Julian Oscillation Investigation Experiment (AMIE) field campaigns in the equatorial Indian Ocean to study the initiation of the Madden-Julian Oscillation (MJO) are used to examine the precipitation, cloud, and moisture characteristics during the MJO and convectively coupled Kelvin waves (KWs). Three MJO events and 10 KWs were identified from satellite data using different wave number frequency filters, although event identification varied based on the chosen range of latitude, frequency, and outgoing longwave radiation threshold. Radar and sounding data were composited for the three MJO events, four KWs during the active MJO, five KWs during the suppressed MJO, and one KW during the developing MJO. The MJO composite was generally consistent with past studies, although an increase in convective rain appeared to precede relative humidity increases at low- to middle-levels. The active and developing MJO KWs produced more rain and cloud than suppressed MJO KWs and had a secondary peak in stratiform rain potentially associated with subsynoptic-scale cloud clusters. The suppressed MJO KW composite displayed previously documented structure of vertical moisture buildup prior to the KW passage, whereas the developing MJO KW did not. The KW moisture signature during the active MJO was somewhat overwhelmed by the moist environment associated with the active MJO. Upper level moisture was enhanced after KW passage, regardless of MJO phase. However, upper level moisture was most enhanced after the developing MJO KW passage, providing deep tropospheric moisture that may have assisted MJO onset. Nonprecipitating upper level cloud and midlevel altocumulus/altostratus also persisted after most KW passages. © 2014. American Geophysical Union. All Rights Reserved."
"9537045600;6603768446;7003283811;35331137500;","The dual wavelength ratio Knee: A signature of multiple scattering in airborne Ku-Ka observations",2014,"10.1175/JAMC-D-13-0341.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84904859380&doi=10.1175%2fJAMC-D-13-0341.1&partnerID=40&md5=8eee62cea14def6e6896934f01098a46","Deep convective systems observed by the High Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) radar during the 2011 Midlatitude Continental Convective Clouds Experiment (MC3E) field campaign in Oklahoma provide the first evidence of multiple-scattering effects simultaneously at Ku and Ka band. One feature is novel and noteworthy: often, in correspondence to shafts with strong convection and when moving from the top of the cloud downward, the dual wavelength ratio (DWR) first increases as usual in Ku-Ka-band observations, but then it reaches a maximum and after that point it steadily decreases all the way to the surface, forming what will be hereinafter referred to as a knee. This DWR knee cannot be reproduced by single-scattering theory under almost any plausible cloud microphysical profile. On the other hand, it is explained straightforwardly with the help of multiple-scattering theory when simulations involving hail-bearing convective cores with large horizontal extents are performed. The DWR reduction in the lower troposphere (i.e., DWR increasing with altitude) is interpreted as the result of multiple-scattering pulse stretching caused by the highly diffusive hail layer positioned high up in the atmosphere, with Ka multiple scattering typically exceeding that occurring in the Ku channel. Since the effects of multiple scattering increase with increasing footprint size, if multiple-scattering effects are present in the aircraft measurements, they are likely to be more pronounced in the spaceborne dual-frequency Ku-Ka radar observations, envisaged for the NASA-Japan Aerospace Exploration Agency (JAXA) Global Precipitation Measurement (GPM) Mission, launched in February 2014. This notional study supports the idea that DWR knees will be observed by the GPM radar when overflying high-density ice shafts embedded in large convective systems and suggests that their explanation must not be sought in differential attenuation or differential Mie effects but via multiple-scattering effects. © 2014 American Meteorological Society."
"6506491601;7005913300;7402711358;6701634159;26643481800;","Ultraviolet actinic flux in clear and cloudy atmospheres: Model calculations and aircraft-based measurements",2011,"10.5194/acp-11-5457-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79959957484&doi=10.5194%2facp-11-5457-2011&partnerID=40&md5=5493531bbc74802ff26403dc34b0760b","Ultraviolet (UV) actinic fluxes measured with two Scanning Actinic Flux Spectroradiometers (SAFS) aboard the NASA DC-8 aircraft are compared with the Tropospheric Ultraviolet-Visible (TUV) model. The observations from 17 days in July-August 2004 (INTEX-NA field campaign) span a wide range of latitudes (28°N-53° N), longitudes (45° Wĝ€""140° W), altitudes (0.1ĝ€""11.9 km), ozone columns (285-353 DU), and solar zenith angles (2°85°). Both cloudy and cloud-free conditions were encountered. For cloud-free conditions, the ratio of observed to clear-sky-model actinic flux (integrated from 298 to 422 nm) was 1.01&plusmn;0.04, i.e. in good agreement with observations. The agreement improved to 1.00&plusmn;0.03 for the down-welling component under clear sky conditions. In the presence of clouds and depending on their position relative to the aircraft, the up-welling component was frequently enhanced (by as much as a factor of 8 relative to cloud-free values) while the down-welling component showed both reductions and enhancements of up to a few tens of percent. Including all conditions, the ratio of the observed actinic flux to the cloud-free model value was 1.1&plusmn;0.3 for the total, or separately 1.0&plusmn;0.2 for the down-welling and 1.5&plusmn;0.8 for the up-welling components. The correlations between up-welling and down-welling deviations are well reproduced with sensitivity studies using the TUV model, and are understood qualitatively with a simple conceptual model. This analysis of actinic flux observations illustrates opportunities for future evaluations of photolysis rates in three-dimensional chemistry-transport models. © 2011 Author(s)."
"8401004800;6602516156;7004557737;56234308500;8663598300;57201124395;15726759700;6506848120;7006471143;6603254448;6603213300;6701802579;7003765782;6701774457;7003620360;8442084800;7004944088;56187256200;57189215242;35490380800;7005941217;7404247296;55914429700;","Evidence for heterogeneous chlorine activation in the tropical UTLS",2011,"10.5194/acp-11-241-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78651277901&doi=10.5194%2facp-11-241-2011&partnerID=40&md5=bbe9e6970ad3be96faee1dd9e5f5c581","Airborne in-situ observations of ClO in the tropics were made during the TROCCINOX (Aracatuba, Brazil, February 2005) and SCOUT-O3 (Darwin, Australia, November/December 2005) field campaigns. While during most flights significant amounts of ClO (≈10-20 parts per trillion, ppt) were present only in aged stratospheric air, instances of enhanced ClO mixing ratios of up to 40 ppt - significantly exceeding those expected from gas phase chemistry - were observed in air masses of a more tropospheric character. Most of these observations are associated with low temperatures or with the presence of cirrus clouds (often both), suggesting that cirrus ice particles and/or liquid aerosol at low temperatures may promote significant heterogeneous chlorine activation in the tropical upper troposphere lower stratosphere (UTLS). In two case studies, particularly high levels of ClO observed were reproduced by chemistry simulations only under the assumption that significant denoxification had occurred in the observed air. However, to reproduce the ClO observations in these simulations, O3 mixing ratios higher than observed had to be assumed, and at least for one of these flights, a significant denoxification is in contrast to the observed NO levels, suggesting that the coupling of chlorine and nitrogen compounds in the tropical UTLS may not be completely understood. © 2011 Author(s)."
"35213800200;7801634218;","The minor importance of giant aerosol to precipitation development within small trade wind cumuli observed during RICO",2010,"10.1016/j.atmosres.2009.11.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-75849164720&doi=10.1016%2fj.atmosres.2009.11.002&partnerID=40&md5=a3689520c70a9f2148737dd180de2157","The present study examines the importance of giant aerosol to precipitation development in marine trade wind cumuli with a new analysis method of a new extensive dataset collected during the Rain in Cumulus over the Ocean (RICO) field campaign. Giant aerosol particles were quantified from clear-air aircraft data, and the precipitation development in the clouds was tracked with dual-polarization radar data. For six different days and multiple clouds on each day, the evolution of the maximum reflectivity, and its associated differential reflectivity, was analyzed. These data were compared with the results of microphysical calculations run within an adiabatic parcel model initialized with the environmental conditions and giant aerosol concentrations on each day of interest. Despite all clouds having formed in a similar maritime environment, this study found substantial variability in the radar echo development both in clouds observed during the same day, and across other days. The maximum reflectivity attained by the clouds appeared to be largely a function of their depth. The radar echo evolution could be represented fairly well by the microphysical parcel model initialized with the observed giant aerosol in some cases but not others. The importance of the giant aerosol to precipitation formation in the small trade wind cumuli appears to be minor: the early radar echoes appear to be more consistent with the development of precipitation by collision and coalescence among droplets formed on the more numerous and smaller cloud condensation nuclei, although the number of giant aerosol appears to have some effect on the actual radar reflectivity values. © 2009 Elsevier B.V. All rights reserved."
"8937358700;6701431208;57062286700;7005054220;6701413579;35497573900;6602743250;7006709050;57199936302;16481344300;","Analysis of convective transport and parameter sensitivity in a single column version of the goddard earth observation system, version 5, general circulation model",2009,"10.1175/2008JAS2694.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-69849107350&doi=10.1175%2f2008JAS2694.1&partnerID=40&md5=0212b0f662a60f32e7b0460065035335","Convection strongly influences the distribution of atmospheric trace gases. General circulation models (GCMs) use convective mass fluxes calculated by parameterizations to transport gases, but the results are difficult to compare with trace gas observations because of differences in scale. The high resolution of cloud-resolving models (CRMs) facilitates direct comparison with aircraft observations. Averaged over a sufficient area, CRM results yield a validated product directly comparable to output from a single global model grid column. This study presents comparisons of vertical profiles of convective mass flux and trace gas mixing ratios derived from CRM and single column model (SCM) simulations of storms observed during three field campaigns. In all three cases, SCM simulations underpredicted convective mass flux relative to CRM simulations. As a result, the SCM simulations produced lower trace gas mixing ratios in the upper troposphere in two of the three storms than did the CRM simulations. The impact of parameter sensitivity in the moist physics schemes employed in the SCM has also been examined. Statistical techniques identified the most significant parameters influencing convective transport. Convective mass fluxes are shown to be strongly dependent on chosen parameter values. Results show that altered parameter settings can substantially improve the comparison between SCM and CRM convective mass flux. Upper tropospheric trace gas mixing ratios were also improved in two storms. In the remaining storm, the SCM representation of CO2 was not improved because of differences in entrainment and detrainment levels in the CRM and SCM simulations. © 2009 American Meteorological Society."
"7004022660;55393706100;7003730283;19034061100;57202119596;6603372003;7003746043;8430317400;6602607948;6602515165;6508204901;6701498141;36641431000;7004602459;6603163872;7005786510;7202861038;19036378400;","Actinic radiation and photolysis processes in the lower troposphere: Effect of clouds and aerosols",2002,"10.1023/A:1015774415983","https://www.scopus.com/inward/record.uri?eid=2-s2.0-18444387404&doi=10.1023%2fA%3a1015774415983&partnerID=40&md5=c4aa3c8cb64fb26afecbe2999c722dc9","Within the German Tropospheric Research Program (TFS) a series of projects were performed focussing on aspects of radiation transfer and the effects of UV-radiation on air chemistry. The individual projects covered laboratory investigations, instrument development for photolysis processes as well as field studies of actinic radiation and comparison to model calculations. One and three-dimensional models were tested against field campaign data. The results confirm the improvement of measurement technology achieved through deployment of new techniques like spectroradiometry that offer a wider range of investigations than was previously attainable using chemical actinometry or fixed wavelength filter radiometry. Reasonable agreement was also found between measurements and models for a few selected and well defined cloudy conditions. On the other hand, using simple stratiform geometry models yielded significant deviations between measurement and model in both directions particularly in the case of high zenith angles and with high aerosol load. Further tools both for experimental investigations and for model calculations were developed within the framework of the Troposphere Research Program (TFS) and deficiencies were identified demanding further investigation when broken clouds and more complex cloud layers prevail."
"7003432387;7006377579;7006235542;7005287667;7004047498;7006595513;6602693652;35477504600;6602128405;7006671428;55883059300;","Modelling of aerosol modification resulting from passage through a hill cap cloud",1999,"10.1016/S0169-8095(98)00104-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-6744260775&doi=10.1016%2fS0169-8095%2898%2900104-5&partnerID=40&md5=70fb1bd0c1bd7ede41d00bf2bd3480b8","Data collected at the Great Dun Fell site are used to provide input and comparative output for a computer model of the hill cap cloud system. The aim of the report is to investigate the effect of in-cloud chemical processing in aerosols and trace gases, focusing on the production of S(VI) via the oxidation of SO2 by H2O2. Both airflow, cloud chemistry and cloud microphysics are modelled and compared to upwind, downwind, and summit observations made during the Great Dun Fell field campaign in 1995. The results indicate that there exists a broader droplet size distribution than predicted due to the mixing of separate parcels of air with different trajectories and humidities. Modification of the aerosol size distribution is predominantly due to sulphate production at the expense of sulphur dioxide gas oxidised by hydrogen peroxide. Predicted nucleation scavenging resulted in the loss of the more hygroscopic particles of diameters 0.05-0.13 μm, which by the addition of soluble mass grew to between 0.13 and 0.3 μm in diameter. The less hygroscopic mode comprised approximately 2% of the total mass input and thus did not significantly contribute to the modified sections of the aerosol spectrum. The modified particles were of a size suitable for nucleation scavening, increasing the number of CCN available for future droplet activation. The hygroscopic properties of the modified particles were also affected by the addition of solube mass, such that they would require a lower critical supersaturation for activation (Swietlicki et al., 1999). The level of aerosol augmentation is dependent upon the activation history of the cloud droplets, the concentration of interstitial gas species, and the partitioning of the aerosol ion species."
"56370372900;7005893321;","A study of the influence of riming of ice crystals on snow chemistry during different seasons in precipitating continental clouds",1994,"10.1016/1352-2310(94)00155-E","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028533194&doi=10.1016%2f1352-2310%2894%2900155-E&partnerID=40&md5=6049281060db05658473ee217c171645","During three field campaigns at Mt Sonnblick-SBO-(3106 m a.s.l.), Salzburg, Austria, in winter 1991, spring and summer 1992, a comprehensive study of cloud water and precipitation chemistry was performed including a microscopic study of form, size and degree of riming of precipitating ice crystals. The surface weighted average of the degree of riming of precipitating snow showed large fluctuations during all seasons studied with a range of 0.5-4.5 The average degree of riming was around 2 during the November and June campaigns and 2.6 in March. The attachment of cloud droplets to precipitating ice crystals was found to be the predominant process determining the final composition of a snowflake. This process was found to be active during all seasons studied. The strong seasonality of the sulfate concentration in precipitation at SBO with very low values during winter and high values during summer could be attributed primarily to the corresponding fluctuation of the sulfate concentration in the cloud water while the extent of riming was rather similar at least during the periods of our winter and summer campaigns. There are indications that the extent of riming is higher during the spring season as compared to winter or summer conditions which might help to explain the spring maximum of sulfate observed in continental precipitation. the amount of cloud water being attached to the ice crystals in relation to the amount of unrimed ice phase in the riming process was estimated to be around 30% during November and June and around 70% in March. The ice crystal shapes and size distributions observed during different cloud temperatures were according to the scheme of Magono and Lee (Journal of the Faculty of Science of Hokkaido University, Series VII, 1966, 2, 321-335). © 1994."
"56993642000;7402027161;6602999057;26422803600;55783064400;7006837187;7006377579;57193496623;7201787800;7103197731;22834248200;7003696133;57189498750;","Numerical simulations of aerosol radiative effects and their impact on clouds and atmospheric dynamics over southern West Africa",2018,"10.5194/acp-18-9767-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049830649&doi=10.5194%2facp-18-9767-2018&partnerID=40&md5=2c83c8e360a44ad3a86fc0af8abb225c","Southern West Africa (SWA) is undergoing rapid and significant socioeconomic changes associated with a massive increase in air pollution. Still, the impact of atmospheric pollutants, in particular that of aerosol particles, on weather and climate in this region is virtually unexplored. In this study, the regional-scale model framework COSMO-ART is applied to SWA for a summer monsoon process study on 2-3 July 2016 to assess the aerosol direct and indirect effect on clouds and atmospheric dynamics. The modeling study is supported by observational data obtained during the extensive field campaign of the project DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) in June-July 2016. As indicated in previous studies, a coastal front is observed that develops during daytime and propagates inland in the evening (Atlantic inflow). Increasing the aerosol amount in COSMO-ART leads to reduced propagation velocities with frontal displacements of 10-30km and a weakening of the nocturnal low-level jet. This is related to a subtle balance of processes related to the decrease in near-surface heating: (1) flow deceleration due to reduced land-sea temperature contrast and thus local pressure gradient, (2) reduced turbulence favoring frontal advance inland and (3) delayed stratus-to-cumulus transition of 1-2h via a later onset of the convective boundary layer. The spatial shift of the Atlantic inflow and the temporal shift of the stratus-to-cumulus transition are synergized in a new conceptual model. We hypothesize a negative feedback of the stratus-to-cumulus transition on the Atlantic inflow with increased aerosol. The results exhibit radiation as the key player governing the aerosol affects on SWA atmospheric dynamics via the aerosol direct effect and the Twomey effect, whereas impacts on precipitation are small. © 2018 Author(s)."
"55351266200;23668563600;7401836526;26644916900;56909327200;","Numerics and subgrid-scale modeling in large eddy simulations of stratocumulus clouds",2017,"10.1002/2016MS000778","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026642909&doi=10.1002%2f2016MS000778&partnerID=40&md5=14ec5e79db123e1eefa9fbee478293ac","Stratocumulus clouds are the most common type of boundary layer cloud; their radiative effects strongly modulate climate. Large eddy simulations (LES) of stratocumulus clouds often struggle to maintain fidelity to observations because of the sharp gradients occurring at the entrainment interfacial layer at the cloud top. The challenge posed to LES by stratocumulus clouds is evident in the wide range of solutions found in the LES intercomparison based on the DYCOMS-II field campaign, where simulated liquid water paths for identical initial and boundary conditions varied by a factor of nearly 12. Here we revisit the DYCOMS-II RF01 case and show that the wide range of previous LES results can be realized in a single LES code by varying only the numerical treatment of the equations of motion and the nature of subgrid-scale (SGS) closures. The simulations that maintain the greatest fidelity to DYCOMS-II observations are identified. The results show that using weighted essentially non-oscillatory (WENO) numerics for all resolved advective terms and no explicit SGS closure consistently produces the highest-fidelity simulations. This suggests that the numerical dissipation inherent in WENO schemes functions as a high-quality, implicit SGS closure for this stratocumulus case. Conversely, using oscillatory centered difference numerical schemes for momentum advection, WENO numerics for scalars, and explicitly modeled SGS fluxes consistently produces the lowest-fidelity simulations. We attribute this to the production of anomalously large SGS fluxes near the cloud tops through the interaction of numerical error in the momentum field with the scalar SGS model. © 2017. The Authors."
"57193933577;7004479957;","Skill of ship-following large-eddy simulations in reproducing MAGIC observations across the northeast Pacific stratocumulus to cumulus transition region",2017,"10.1002/2017MS000924","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017527486&doi=10.1002%2f2017MS000924&partnerID=40&md5=199e5650c02e0c2352641fc630572e6e","During the Marine ARM GPCI Investigation of Clouds (MAGIC) in October 2011 to September 2012, a container ship making periodic cruises between Los Angeles, CA, and Honolulu, HI, was instrumented with surface meteorological, aerosol and radiation instruments, a cloud radar and ceilometer, and radiosondes. Here large-eddy simulation (LES) is performed in a ship-following frame of reference for 13 four day transects from the MAGIC field campaign. The goal is to assess if LES can skillfully simulate the broad range of observed cloud characteristics and boundary layer structure across the subtropical stratocumulus to cumulus transition region sampled during different seasons and meteorological conditions. Results from Leg 15A, which sampled a particularly well-defined stratocumulus to cumulus transition, demonstrate the approach. The LES reproduces the observed timing of decoupling and transition from stratocumulus to cumulus and matches the observed evolution of boundary layer structure, cloud fraction, liquid water path, and precipitation statistics remarkably well. Considering the simulations of all 13 cruises, the LES skillfully simulates the mean diurnal variation of key measured quantities, including liquid water path (LWP), cloud fraction, measures of decoupling, and cloud radar-derived precipitation. The daily mean quantities are well represented, and daily mean LWP and cloud fraction show the expected correlation with estimated inversion strength. There is a −0.6 K low bias in LES near-surface air temperature that results in a high bias of 5.6 W m−2 in sensible heat flux (SHF). Overall, these results build confidence in the ability of LES to represent the northeast Pacific stratocumulus to trade cumulus transition region. © 2017. The Authors."
"14018977200;7004091067;55968364300;55814166200;8147766700;7006029393;54788283700;55422107100;","Forecasting atmospheric rivers during calwater 2015",2017,"10.1175/BAMS-D-15-00245.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016939976&doi=10.1175%2fBAMS-D-15-00245.1&partnerID=40&md5=b9a36c1511f5155602f7a50c8e431a16","The purpose of this article is to highlight different tools that were developed and used to analyze and forecast the location, intensity, duration, and potential landfall of regions of water vapor transport along ARs during an observing campaign over the northeast Pacific during January–March 2015 named CalWater 2015. CalWater is a multiyear program of field campaigns, numerical modeling efforts, and scientific analyses focused on phenomena that are key to the water supply and associated extremes across the western US. The National Science Foundation and DOE have also sponsored an overlap-ping major aerosol and cloud measurement experi¬ment at the coast called the Atmospheric Radiation Measurement (ARM) Cloud Aerosol Precipitation Experiment (ACAPEX) during January–March 2015 to analyze CalWater."
"26422803600;7003510880;13006677900;","Nocturnal low-level clouds over southern West Africa analysed using high-resolution simulations",2017,"10.5194/acp-17-899-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010041793&doi=10.5194%2facp-17-899-2017&partnerID=40&md5=0708aca4ed31f6d6c0e519a2ec66216b","We performed a high-resolution numerical simulation to study the development of extensive low-level clouds that frequently form over southern West Africa during the monsoon season. This study was made in preparation for a field campaign in 2016 within the Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) project and focuses on an area around the city of Savè in southern Benin. Nocturnal low-level clouds evolve a few hundred metres above the ground around the same level as a distinct low-level jet. Several processes are found to determine the spatio-temporal evolution of these clouds including (i) significant cooling of the nocturnal atmosphere caused by horizontal advection with the south-westerly monsoon flow during the first half of the night, (ii) vertical cold air advection due to gravity waves leading to clouds in the wave crests and (iii) enhanced convergence and upward motion upstream of existing clouds that trigger new clouds. The latter is caused by an upward shift of the low-level jet in cloudy areas leading to horizontal convergence in the lower part and to horizontal divergence in the upper part of the cloud layer. Although this single case study hardly allows for a generalisation of the processes found, the results added to the optimisation of the measurements strategy for the field campaign and the observations will be used to test the hypotheses for cloud formation resulting from this study. © Author(s) 2017.."
"56463153400;23065650200;","Developing and bounding ice particle mass- and area-dimension expressions for use in atmospheric models and remote sensing",2016,"10.5194/acp-16-4379-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964528081&doi=10.5194%2facp-16-4379-2016&partnerID=40&md5=b11981edc2e294cc246e3c87e8dbcd9c","Ice particle mass- and projected area-dimension (m-D and A-D) power laws are commonly used in the treatment of ice cloud microphysical and optical properties and the remote sensing of ice cloud properties. Although there has long been evidence that a single m-D or A-D power law is often not valid over all ice particle sizes, few studies have addressed this fact. This study develops self-consistent m-D and A-D expressions that are not power laws but can easily be reduced to power laws for the ice particle size (maximum dimension or D) range of interest, and they are valid over a much larger D range than power laws. This was done by combining ground measurements of individual ice particle m and D formed at temperature T < -20°C during a cloud seeding field campaign with 2-D stereo (2D-S) and cloud particle imager (CPI) probe measurements of D and A, and estimates of m, in synoptic and anvil ice clouds at similar temperatures. The resulting m-D and A-D expressions are functions of temperature and cloud type (synoptic vs. anvil), and are in good agreement with m-D power laws developed from recent field studies considering the same temperature range (-60°C < T < -20°C). © 2016 Author(s)."
"12800966700;57202425542;8657166100;7003535385;","Ice Crystal sizes in high ice water content clouds. Part I: On the computation of median mass diameter from in situ measurements",2016,"10.1175/JTECH-D-15-0151.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995436821&doi=10.1175%2fJTECH-D-15-0151.1&partnerID=40&md5=3a57eef1da540ff138e2d09b50ef57e3","Engine and air data probe manufacturers, as well as aviation agencies, are interested in better characterization of high ice water content (HIWC) areas close to thunderstorms, since HIWC conditions are suspected to cause in-service engine power loss and air data events on commercial aircraft. In this context, a collaborative field campaign has been conducted by high-altitude ice crystals (HAIC) and HIWC projects in order to provide ice water content and median mass diameter (MMD) of ice crystals in the HIWC environment. The computation of MMD from in situ measurements relies mainly on the definition of the crystal dimension D and on the m=αDβ relationship, which is used to convert number into mass distributions. The first part of this study shows that MMD can significantly deviate when using different mass-size relationships from the literature. Sensitivity tests demonstrate that MMD is significantly impacted by the choice of β. However, the larger contributor to MMD differences seems to be the choice of the size definition D itself. Since MMDs are quite sensitive to β, this study suggests a generic method for deducing β solely from optical array probes (OAPs) image data for various size definitions. The method is based on simulations of 3D crystal objects projected onto a 2D plane, thereby relating crystal mass to 2D area (projection) and perimeter. The MMD values calculated for different size definitions are quite similar, at least much closer than MMDs derived from different m(D) relationships in the literature. © 2016 American Meteorological Society."
"57190300360;6505932008;6602805147;7005968859;","The microphysical contributions to and evolution of latent heating profiles in two MC3E MCSs",2016,"10.1002/2016JD024762","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979079595&doi=10.1002%2f2016JD024762&partnerID=40&md5=fab5560ef9b2aeb3fa2d56c73fb15351","The shapes and magnitudes of latent heating profiles have been shown to be different within the convective and stratiform regions of mesoscale convective systems (MCSs). Properly representing these distinctions has significant implications for the atmospheric responses to latent heating on various scales. This study details (1) the microphysical process contributions to latent heating profiles within MCS convective, stratiform, and anvil regions and (2) the time evolution of these profiles throughout the MCS lifetime, using cloud-resolving model simulations. Simulations of two MCS events that occurred during the Midlatitude Continental Convective Clouds Experiment (MC3E) are conducted. Several features of the simulated MCSs are compared to a suite of observations obtained during the MC3E field campaign, and it is concluded that the simulations reasonably reproduce the MCS events. The simulations show that condensation and deposition are the primary contributors to MCS latent warming, as compared to riming and nucleation processes. In terms of MCS latent cooling, sublimation, melting, and evaporation all play significant roles. It is evident that throughout the MCS lifecycle, convective regions demonstrate an approximately linear decrease in the magnitudes of latent heating rates, while latent heating within stratiform regions is associated with transitions between MCS flow regimes. Such information regarding the temporal evolution of latent heating within convective and stratiform MCS regions could be useful in developing parameterizations representing convective organization. © 2016. American Geophysical Union. All Rights Reserved."
"24168416900;7103016965;9044746800;7102591209;","The sensitivity of simulated high clouds to ice crystal fall speed, shape and size distribution",2015,"10.1002/qj.2457","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84939443127&doi=10.1002%2fqj.2457&partnerID=40&md5=f4550a87b6ec81d42d1b0e0c10834ca8","The sensitivity of an operational numerical weather prediction model to the parametrized microphysical properties of ice hydrometeors is examined. The effects of varying ice-particle size distribution, fall speed, mass and depositional capacitance are considered in kilometre-scale simulations of midlatitude cloud systems and 20 year global climate integrations. It is shown that the observed sensitivity can be obtained from steady-state arguments, whereby the vertical moisture flux is balanced by the hydrometeor sedimentation flux and supersaturation production is in equilibrium with depositional growth. The high-resolution simulations are compared with in situ measurements from the Constrain field campaign (Prestwick, UK). © 2015 Royal Meteorological Society."
"54781196300;7102866124;","Cloud and rain liquid water statistics in the CHUVA campaign",2014,"10.1016/j.atmosres.2014.03.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84899637645&doi=10.1016%2fj.atmosres.2014.03.006&partnerID=40&md5=22f405c762b7eee681ae3d686ab2e6c7","The purpose of this study is to present statistics related to the integration of cloud and rain liquid water and the profiles for different cloud types and regimes. From 2010 to 2012, the CHUVA project collected information regarding cloud and rain characteristics in different precipitation regimes in Brazil. CHUVA had four field campaigns between 2010 and 2011, located in the North, Northeast and Southeast regions of Brazil, covering the semi-arid, Amazon, coastal and mountain regions. The synergy of several instruments allowed us to classify rain events and describe the cloud processes regionally. Microwave radiometers, LiDAR, radar, and disdrometers were employed in this study. The rain type classification was made using vertical profiles of reflectivity (VPR) and polarimetric variables from dual polarization radar (XPOL). The integrated liquid water (ILWC) for non-precipitating clouds was retrieved with a microwave ground-based radiometer using a neural network. For rainy conditions, the profiles from the rain liquid water content (LWCR) and their integrated (ILWR) properties were estimated by Micro Rain Radar (MRR) and XPOL VPRs. For non-precipitating clouds, the ILWC values were larger for the sites in tropical regions, in particular near the coast, than for Southeast Brazil. For rainy cases, distinct LWCR profiles were observed for different rain classifications and regions. The differences are small for low rain rates and a distinction between different rainfall regimes is more evident for high rain rates. Vale and Belém clouds present the deepest layers and largest convective rain rates. The clouds in the Southeast region of Brazil (Vale do Paraíba) and North region (Belém) showed the largest reflectivity in the mixed and glaciated layers, respectively. In contrast, the Northeast coastal site (e.g. Fortaleza) showed larger values in the warm part of the clouds. Several analyses are presented, describing the cloud processes and the differences among the cloud types, rain rates and regions. © 2014 Elsevier B.V."
"57203209031;26632290800;","Low-altitude summer/winter microphysics, dynamics, and CCN spectra of northeastern Caribbean small cumuli, and comparisons with stratus",2014,"10.1002/2013JD021442","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84901713712&doi=10.1002%2f2013JD021442&partnerID=40&md5=faa0ce45782c8c45f81f2890bfbcaf04","Low-altitude cloud microphysics and cloud condensation nuclei (CCN) spectra are presented and analyzed from two cumulus cloud aircraft field campaigns, Ice in Clouds Experiment-Tropical (ICE-T) and Rain in Cumulus over the Ocean (RICO), in the same eastern Caribbean location at opposite seasons. These are further compared with two previously analyzed stratus cloud aircraft campaigns off the central California coast, Physics of Stratocumulus Tops (POST) and Marine Stratus/Stratocumulus Experiment (MASE). Multiple regression analysis predictions of cloud droplet concentrations (Nc) based on CCN spectra, NCCN(S) where S is supersaturation, compared much better with measured Nc than single NCCN-Nc regressions in both cumulus projects. The addition of vertical velocity (W) to the single and multiple regressions showed small improvements. For RICO the multiple regression correlations were also superior to previous adiabatic model predictions of Nc also based on NCCN(S) and mean W. More adiabatic cloud parcels with considerably higher Nc, liquid water contents, and W showed only slightly better correlations than flight-averaged Nc of all low clouds. Results show the value of more extensive CCN spectra and the relative unimportance of W variations for determining Nc, in these Caribbean cumuli. The fact that flight-averaged Nc of all low cloud data was almost as well correlated with NCCN(S) as were Nc of more adiabatic cloud parcels indicates that entrainment did not significantly perturb CCN-Nc relationships. As should be expected higher cloud S were determined for the cumulus clouds than for the stratus clouds. Suppression of cloud S by higher NCCN that had previously been observed in stratus was observed in ICE-T but not in RICO where the NCCN range may have been too low for cloud S suppression. But ICE-T and POST even showed this S suppression over the same limited NCCN range as RICO (&lt; 200 cm-3). © 2014. American Geophysical Union. All Rights Reserved."
"7102743829;6506537159;55934894800;","Effects of sea-salt aerosols on precipitation in simulations of shallow cumulus",2012,"10.1175/JAS-D-11-031.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857207195&doi=10.1175%2fJAS-D-11-031.1&partnerID=40&md5=6232513e7d518586d309c7e753da4244","A suite of large-eddy simulations with size-resolving microphysical processes was performed in order to assess effects of sea-salt aerosols on precipitation process in trade cumulus. Simulations based on observations from the Rain in Cumulus over the Ocean (RICO) field campaign explored the effects of adding sea-salt nuclei in different size ranges by following the evolution of 369 cloud cells over the 24-h simulation period. The addition of large (small) sea-salt nuclei tends to accelerate (suppress) precipitation formation; however, in marine environments the sea-salt spectra always include a combination of both small (film) and large (jet) nuclei. When realistic sea-salt spectra are specified as a function of surface wind, the effect of the larger nuclei to enhance the precipitation predominates, and accumulated precipitation increases with wind speed. This effect, however, is strongly influenced by the choice of background CCN spectrum. Adding the same sea-salt specification to an environment with a higher background aerosol load results in a decrease in accumulated precipitation with increasing surface wind speed. Results also suggest that the slope of the relationship between vertical velocityWand the concentration of embryonic precipitation particles at cloud base N r may indicate the role of sea-salt nuclei. A negative slope (N r decreasing with increasingW) points to the predominance of small sea-salt nuclei, in which larger updrafts activate a greater number of smaller cloud drops with smaller coalescence efficiencies, resulting in fewer embryonic rain drops. A positive slope, on the other hand, indicates the presence of large sea-salt nuclei, which are the source of embryonic rain drops. © 2012 American Meteorological Society."
"36059844000;7102643810;7006575272;7004484970;","Evaluating the snow crystal size distribution and density assumptions within a single-moment microphysics scheme",2010,"10.1175/2010MWR3485.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650189514&doi=10.1175%2f2010MWR3485.1&partnerID=40&md5=286a8fa5eb8f0f3d0a225c5079f13de0","The Canadian CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Validation Project (C3VP) was a field campaign designed to obtain aircraft, surface, and radar observations of clouds and precipitation in support of improving the simulation of snowfall and cold season precipitation, their microphysical processes represented within forecast models, and radiative properties relevant to remotely sensed retrievals. During the campaign, a midlatitude cyclone tracked along the U.S.-Canadian border on 22 January 2007, producing an extensive area of snowfall. Observations of ice crystals from this event are used to evaluate the assumptions and physical relationships for the snow category within the Goddard six-class, single-moment microphysics scheme, as implemented within the Weather Research and Forecasting (WRF) model. The WRF model forecast generally reproduced the precipitation and cloud structures sampled by radars and aircraft, permitting a comparison between C3VP observations and model snowfall characteristics. Key snowfall assumptions in the Goddard scheme are an exponential size distribution with fixed intercept and effective bulk density, and the relationship between crystal diameter and terminal velocity. Fixed values for the size distribution intercept and density did not represent the vertical variability of naturally occurring populations of aggregates, and the current diameter and fall speed relationship underestimated terminal velocities for all sizes of crystals. © 2010 American Meteorological Society."
"6602134507;35584010200;7005729142;16185051500;35572096100;7003406689;6506385754;36058918500;6603585457;","TRMM common microphysics products: A tool for evaluating spaceborne precipitation retrieval algorithms",2004,"10.1175/JAM2151.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-11344294322&doi=10.1175%2fJAM2151.1&partnerID=40&md5=1596d86a2c578f6643cbf82b1d09b46c","A customized product for analysis of microphysics data collected from aircraft during field campaigns in support of the Tropical Rainfall Measuring Mission (TRMM) program is described. These ""common microphysics products"" (CMPs) are designed to aid in evaluation of TRMM spaceborne precipitation retrieval algorithms. Information needed for this purpose (e.g., particle size spectra and habit, liquid and ice water content) was derived by using a common processing strategy on the wide variety of microphysical instruments and raw native data formats employed in the field campaigns. The CMPs are organized into an American Standard Code for Information Interchange (ASCII) structure to allow easy access to the data for those less familiar with microphysical data processing and without the tools to accomplish it. Detailed examples of the CMP show its potential and some of its limitations. This approach may be a first step toward developing a generalized microphysics format and an associated community-oriented, nonproprietary software package for microphysics data processing-initiatives that would likely broaden community access to, and use of, microphysics datasets. © 2004 American Meteorological Society."
"6506942596;7102018821;15032788000;7007061674;","Simultaneous retrieval of aerosol and thin cirrus optical depths using MODIS airborne simulator data during CRYSTAL-FACE and CLAMS",2004,"10.1029/2004GL020457","https://www.scopus.com/inward/record.uri?eid=2-s2.0-10644225234&doi=10.1029%2f2004GL020457&partnerID=40&md5=7e5a24aaacf1f090b8dbdf936145263f","We have developed a new methodology to simultaneously retrieve the optical depths of aerosols and thin cirrus clouds over the oceans by using the Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator (MAS) data. This methodology takes advantage of the fact that the visible (or a near-infrared window) reflectance from cirrus can be characterized by its correlation to the reflectance from a near-infrared band located in a strong water vapor absorption region. Once the reflectance due to cirrus has been removed, the residual reflectance in these bands is used to retrieve aerosol optical depth. Cirrus cloud properties are subsequently obtained by minimizing the difference between observed and calculated reflectance values stored in look-up tables that are constructed a priori and correlated to the retrieved aerosol optical depth. Examination of the data gathered from the recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) and Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaigns demonstrates that our retrievals are consistent with both in-situ and ground based measurements. Copyright 2004 by the American Geophysical Union."
"7201646465;55476510600;56853406500;","Sensitivity of simulated mesoscale atmospheric circulations resulting from landscape heterogeneity to aspects of model configuration",2002,"10.1029/2001JD000376","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646504401&doi=10.1029%2f2001JD000376&partnerID=40&md5=1598bf35641726babfa530179a24c763","Recent work has demonstrated the importance of anthropogenic landscape heterogeneity in Amazonia and the central U.S. in forcing mesoscale atmospheric circulations and generating clouds and precipitation. It has been shown that failing to account for this surface heterogeneity may have important implications for the simulation of land-atmosphere interactions in large-scale atmospheric models. The work presented here shows that, in addition to correctly specifying the surface forcing, accurate simulation of landscape-induced mesoscale effects with a regional model (e.g., Regional Atmospheric Modeling System, RAMS) depends critically on informed choices of aspects of model configuration. These include horizontal resolution, strength of nudging, and atmospheric initialization. Sensitivity experiments designed to illustrate the impact of varying these factors on RAMS-simulated, landscape-induced mesoscale circulations are presented here. These results, supported by dynamical and scaling arguments, suggest that model configuration can have at least as great an impact on the simulated mesoscale circulations, fluxes, and PBL structure as correctly accounting for mesoscale landscape heterogeneity. Such experiments therefore provide crucial guidance for optimally constructing simulations of mesoscale land-atmosphere interaction important for a variety of applications from field campaigns to parameterization development. Copyright 2002 by the American Geophysical Union."
"7005174340;57196676724;56423879400;7003375617;7003427696;15072262300;35998927000;7102708429;6603816167;6602215448;7005550877;7003613864;6701831920;","Aerosol-radiation interaction in the cloudless atmosphere during LACE 98 1. Measured and calculated broadband solar and spectral surface insolations",2002,"10.1029/2000JD000226","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0043035624&doi=10.1029%2f2000JD000226&partnerID=40&md5=1e89976b5f699006a8c4f28f21fce9c4","Vertical profile measurements of aerosol particle size distributions and of meteorological parameters (obtained from aircraft, radiosondes, and lidar) are used as input to a spectral radiative transfer model to calculate broadband solar and spectral surface insolations. The calculated values are compared to measured ones gathered with broadband solar pyranometers and pyrheliometers, and a fixed-grating photodiode array spectroradiometer with 512 spectral channels between 500 and 920 nm wavelength. The measurements were obtained during the joint field campaign Lindenberg Aerosol Characterization Experiment (LACE) 98 near Berlin/Germany in the summer of 1998. Two cases (days with high and low aerosol loading, respectively) are investigated in detail. Furthermore, a measurement-based sensitivity analysis was carried out focusing on the influence of particle composition (complex refractive index) and of microphysical and humidity growth uncertainties on the calculated surface insolations. Assuming a spectral refractive index of ammonium sulfate for the aerosol particles, on average the global component of the broadband solar surface insolations is 11-20 W m-2 (2-3%) greater than the measured values; the direct portion is 17-28 W m-2 (4-5%) higher, and its diffuse component is 6-7 W m -2 (4-10%) lower in comparison to the measurements. The measured and calculated spectral surface insolations (global portion) agree well in the central visible spectral region (500-600 nm wavelength). Toward larger wavelengths (near infrared) the calculated spectral surface insolations are increasingly higher than the measured ones. Copyright 2002 by the American Geophysical Union."
"7405627793;7006717013;7004402705;7006532784;","Three-dimensional chemical forecasting: A methodology",1997,"10.1029/96jd00694","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001183809&doi=10.1029%2f96jd00694&partnerID=40&md5=38c59ec8b13996e2f4b92806cc6a481b","During the recent ASHOE (Airborne Southern Hemisphere Ozone Experiment) and SESAME (Second European Stratospheric Arctic and Middle-Latitude Experiment) field campaigns we produced a number of 10-day chemical forecasts of the stratosphere to aid in flight planning and interpretation of the observations. A general circulation model was integrated at high resolution to produce a 10-day meteorological forecast. These forecast fields were then used to specify the circulation in an off-line three-dimensional chemical transport model to produce a medium-range chemical forecast of the stratosphere. The chemical model has a detailed stratospheric chemistry scheme, including heterogeneous reactions on polar stratospheric clouds and sulfate aerosols. The NASA ER-2 high-altitude research aircraft made in situ measurements of chemical tracers in the lower stratosphere during the ASHOE campaign, which took place in four deployments from March to October 1994. This paper presents examples from the chemical forecasts made during the second and fourth deployments. We show that the ability to indicate the likely composition of the atmosphere is an important improvement over the standard meteorological forecasts, especially in air perturbed by chemical processing on polar stratospheric clouds. Of particular interest was the ability to forecast the chemical composition of filaments, which had been eroded from the vortex edge. Furthermore, immediate post-flight comparison between observed data and synoptic model data gave useful chemical interpretation of the observations."
"56888217500;27868213600;7005477332;55499821700;12646426700;6506532311;35868180800;7003444634;57126848900;7003729315;7101707186;57218359395;7004166136;24722339600;6602137800;","Coupled Retrieval of Liquid Water Cloud and Above-Cloud Aerosol Properties Using the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI)",2018,"10.1002/2017JD027926","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044506426&doi=10.1002%2f2017JD027926&partnerID=40&md5=d6dc99c2709698617a95cc54519a5df7","An optimization algorithm is developed to retrieve liquid water cloud properties including cloud optical depth (COD), droplet size distribution and cloud top height (CTH), and above-cloud aerosol properties including aerosol optical depth (AOD), single-scattering albedo, and microphysical properties from sweep-mode observations by Jet Propulsion Laboratory's Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) instrument. The retrieval is composed of three major steps: (1) initial estimate of the mean droplet size distribution across the entire image of 80–100 km along track by 10–25 km across track from polarimetric cloudbow observations, (2) coupled retrieval of image-scale cloud and above-cloud aerosol properties by fitting the polarimetric data at all observation angles, and (3) iterative retrieval of 1-D radiative transfer-based COD and droplet size distribution at pixel scale (25 m) by establishing relationships between COD and droplet size and fitting the total radiance measurements. Our retrieval is tested using 134 AirMSPI data sets acquired during the National Aeronautics and Space Administration (NASA) field campaign ObseRvations of Aerosols above CLouds and their intEractionS. The retrieved above-cloud AOD and CTH are compared to coincident HSRL-2 (HSRL-2, NASA Langley Research Center) data, and COD and droplet size distribution parameters (effective radius reff and effective variance veff) are compared to coincident Research Scanning Polarimeter (RSP) (NASA Goddard Institute for Space Studies) data. Mean absolute differences between AirMSPI and HSRL-2 retrievals of above-cloud AOD at 532 nm and CTH are 0.03 and &lt;0.5 km, respectively. At RSP's footprint scale (~ 323 m), mean absolute differences between RSP and AirMSPI retrievals of COD, reff, and veff in the cloudbow area are 2.33, 0.69 μm, and 0.020, respectively. Neglect of smoke aerosols above cloud leads to an underestimate of image-averaged COD by ~15%. ©2018. American Geophysical Union. All Rights Reserved."
"6602078681;7004866567;55621952600;6602458644;56160326300;6505948757;8293958400;7401984344;57209629699;16425297500;7103333823;","Validation of atmospheric profile retrievals from the SNPP NOAA-unique combined atmospheric processing system. Part 1: Temperature and moisture",2018,"10.1109/TGRS.2017.2744558","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030089917&doi=10.1109%2fTGRS.2017.2744558&partnerID=40&md5=9be40d461fe21ab6e0a6ed4a662c2723","This paper provides an overview of the validation of the operational atmospheric vertical temperature profile (AVTP) and atmospheric vertical moisture profile (AVMP) environmental data record (EDR) products retrieved from the Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS), two passive sounding systems onboard the Suomi National Polar-Orbiting Partnership (SNPP) satellite. The CrIS/ATMS suite serves as the U.S. low earth orbit (LEO) satellite sounding system and will span the future Joint Polar Satellite System (JPSS) LEO satellites. The operational sounding algorithm is the National Oceanic and Atmospheric Administration-Unique Combined Atmospheric Processing System (NUCAPS), a legacy sounder science team algorithm capable of retrieving atmospheric profile EDR products with optimal vertical resolution under nonprecipitating (clear to partly cloudy) conditions. The SNPP NUCAPS AVTP and AVMP EDR products are validated using extensive global in situ baseline data sets, namely, radiosonde observations launched from ground-based networks and ocean-based intensive field campaigns, along with numerical weather prediction model output. Based upon statistical analyses using these data sets, the SNPP AVTP and AVMP EDRs are determined to meet the JPSS Level 1 global performance requirements. © 2017 IEEE."
"7003444634;57126848900;22635999400;7203034123;56767841200;35547214900;8627503500;6602407753;57208765879;7202727242;","Polarized view of supercooled liquid water clouds",2016,"10.1016/j.rse.2016.04.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963877334&doi=10.1016%2fj.rse.2016.04.002&partnerID=40&md5=27fc97e8b17c867d5703b314b2499ae5","Supercooled liquid water (SLW) clouds, where liquid droplets exist at temperatures below 0°C present a well-known aviation hazard through aircraft icing, in which SLW accretes on the airframe. SLW clouds are common over the Southern Ocean, and climate-induced changes in their occurrence is thought to constitute a strong cloud feedback on global climate. The two recent NASA field campaigns POlarimeter Definition EXperiment (PODEX, based in Palmdale, California, January-February 2013) and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, based in Houston, Texas in August-September 2013) provided a unique opportunity to observe SLW clouds from the high-altitude airborne platform of NASA's ER-2 aircraft. We present an analysis of measurements made by the Research Scanning Polarimeter (RSP) during these experiments accompanied by correlative retrievals from other sensors. The RSP measures both polarized and total reflectance in 9 spectral channels with wavelengths ranging from 410 to 2250 nm. It is a scanning sensor taking samples at 0.8° intervals within 60° from nadir in both forward and backward directions. This unique angular resolution allows for characterization of liquid water droplet size using the rainbow structure observed in the polarized reflectances in the scattering angle range between 135° and 165°. Simple parametric fitting algorithms applied to the polarized reflectance provide retrievals of the droplet effective radius and variance assuming a prescribed size distribution shape (gamma distribution). In addition to this, we use a non-parametric method, Rainbow Fourier Transform (RFT), which allows retrieval of the droplet size distribution without assuming a size distribution shape. We present an overview of the RSP campaign datasets available from the NASA GISS website, as well as two detailed examples of the retrievals. In these case studies we focus on cloud fields with spatial features varying between glaciated and liquid phases at altitudes as high as 10 km, which correspond to temperatures close to the homogeneous freezing temperature of pure water drops (about -35°C or colder). The multimodal droplet size distributions retrieved from RSP data in these cases are consistent with the multi-layer cloud structure observed by correlative Cloud Physics Lidar (CPL) measurements. © 2016 Elsevier Inc."
"57188817814;24472110700;7102425008;7003875148;","Summer Arctic clouds in the ECMWF forecast model: An evaluation of cloud parametrization schemes",2016,"10.1002/qj.2658","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957849655&doi=10.1002%2fqj.2658&partnerID=40&md5=1da482e18939ea7c235739874eba0f46","Mixed-phase clouds are an integral part of the Arctic climate system, for precipitation and for their interactions with radiation and thermodynamics. Mixed-phase processes are often poorly represented in global models and many use an empirically based diagnostic partition between the liquid and ice phases that is dependent solely on temperature. However, increasingly more complex microphysical parametrizations are being implemented allowing a more physical representation of mixed-phase clouds. This study uses in situ observations from the Arctic Summer Cloud Ocean Study (ASCOS) field campaign in the central Arctic to assess the impact of a change from a diagnostic to a prognostic parametrization of mixed-phase clouds and increased vertical resolution in the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS). The newer cloud scheme improves the representation of the vertical structure of mixed-phase clouds, with supercooled liquid water at cloud top and ice precipitating below, improved further with higher vertical resolution. Increased supercooled liquid water and decreased ice content are both in closer agreement with observations. However, these changes do not result in any substantial improvement in surface radiation, and a warm and moist bias in the lowest part of the atmosphere remains. Both schemes also fail to capture the transitions from overcast to cloud-free conditions. Moreover, whereas the observed cloud layer is frequently decoupled from the surface, the modelled clouds remain coupled to the surface most of the time. The changes implemented to the cloud scheme are an important step forward in improving the representation of Arctic clouds, but improvements in other aspects such as boundary-layer turbulence, cloud radiative properties, sensitivity to low aerosol concentrations and representation of the sea-ice surface may also need to be addressed. © 2016 Royal Meteorological Society."
"36054921000;7102567936;6506545080;34881780600;7006303509;7006783796;8723505700;","Simulations of cloud-radiation interaction using large-scale forcing derived from the CINDY/DYNAMO northern sounding array",2015,"10.1002/2015MS000461","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84945477816&doi=10.1002%2f2015MS000461&partnerID=40&md5=9826627051dfa66ffb01374588788224","The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large-scale forcing data set derived from the DYNAMO northern sounding array observations, and carried out in a doubly periodic domain using the Weather Research and Forecasting (WRF) model. Simulated cloud properties and radiative fluxes are compared to those derived from the S-PolKa radar and satellite observations. To accommodate the uncertainty in simulated cloud microphysics, a number of single-moment (1M) and double-moment (2M) microphysical schemes in the WRF model are tested. The 1M schemes tend to underestimate radiative flux anomalies in the active phases of the MJO events, while the 2M schemes perform better, but can overestimate radiative flux anomalies. All the tested microphysics schemes exhibit biases in the shapes of the histograms of radiative fluxes and radar reflectivity. Histograms of radiative fluxes and brightness temperature indicate that radiative biases are not evenly distributed; the most significant bias occurs in rainy areas with OLR less than 150 W/m2 in the 2M schemes. Analysis of simulated radar reflectivities indicates that this radiative flux uncertainty is closely related to the simulated stratiform cloud coverage. Single-moment schemes underestimate stratiform cloudiness by a factor of 2, whereas 2M schemes simulate much more stratiform cloud. © 2015. The Authors."
"56122121300;7006329853;16027966800;7201488063;57211636621;37099944400;26533129200;","Evaluations of tropospheric aerosol properties simulated by the community earth system model with a sectional aerosol microphysics scheme",2015,"10.1002/2014MS000421","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027950807&doi=10.1002%2f2014MS000421&partnerID=40&md5=edd8a47a93f9906d53e84f850f733427","A sectional aerosol model (CARMA) has been developed and coupled with the Community Earth System Model (CESM1). Aerosol microphysics, radiative properties, and interactions with clouds are simulated in the size-resolving model. The model described here uses 20 particle size bins for each aerosol component including freshly nucleated sulfate particles, as well as mixed particles containing sulfate, primary organics, black carbon, dust, and sea salt. The model also includes five types of bulk secondary organic aerosols with four volatility bins. The overall cost of CESM1-CARMA is approximately 2.6 times as much computer time as the standard three-mode aerosol model in CESM1 (CESM1-MAM3) and twice as much computer time as the seven-mode aerosol model in CESM1 (CESM1-MAM7) using similar gas phase chemistry codes. Aerosol spatial-temporal distributions are simulated and compared with a large set of observations from satellites, ground-based measurements, and airborne field campaigns. Simulated annual average aerosol optical depths are lower than MODIS/MISR satellite observations and AERONET observations by 32%. This difference is within the uncertainty of the satellite observations. CESM1/CARMA reproduces sulfate aerosol mass within 8%, organic aerosol mass within 20%, and black carbon aerosol mass within 50% compared with a multiyear average of the IMPROVE/EPA data over United States, but differences vary considerably at individual locations. Other data sets show similar levels of comparison with model simulations. The model suggests that in addition to sulfate, organic aerosols also significantly contribute to aerosol mass in the tropical UTLS, which is consistent with limited data. © 2015. The Authors."
"42662217100;6603422104;","Cloud regime variability over the Azores and its application to climate model evaluation",2015,"10.1175/JCLI-D-15-0066.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957716899&doi=10.1175%2fJCLI-D-15-0066.1&partnerID=40&md5=2e129666f98b4b52a3d555e34f4a8348","From its location on the subtropics-midlatitude boundary, the Azores is influenced by both the subtropical high pressure and the midlatitude baroclinic storm regimes and therefore experiences a wide range of cloud structures, from fair-weather scenes to stratocumulus sheets and deep convective systems. This work combines three types of datasets to study cloud variability in the Azores: A satellite analysis of cloud regimes, a reanalysis characterization of storminess, and a 19-month field campaign that occurred on Graciosa Island. Combined analysis of the three datasets provides a detailed picture of cloud variability and the respective dynamic influences, with emphasis on low clouds that constitute a major uncertainty source in climate model simulations. The satellite cloud regime analysis shows that the Azores cloud distribution is similar to the mean global distribution and can therefore be used to evaluate cloud simulation in global models. Regime analysis of low clouds shows that stratocumulus decks occur under the influence of the Azores high pressure system, while shallow cumulus clouds are sustained by cold-air outbreaks, as revealed by their preference for postfrontal environments and northwesterly flows. An evaluation of climate model cloud regimes from phase 5 of CMIP (CMIP5) over the Azores shows that all models severely underpredict shallow cumulus clouds, while most models also underpredict the occurrence of stratocumulus cloud decks. It is demonstrated that the regime analysis can assist in the selection of case studies representing specific climatological cloud distributions. With all the tools now in place, a methodology is suggested to better understand cloud-dynamics interactions and attempt to explain and correct climate model cloud deficiencies. © 2015 American Meteorological Society."
"21740519000;36187387300;23981063100;54883121500;7801532509;35169960300;7006760857;7004854393;35737139200;7005246023;7003554893;19639722300;","Representation of daytime moist convection over the semi-arid Tropics by parametrizations used in climate and meteorological models",2015,"10.1002/qj.2517","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84941189190&doi=10.1002%2fqj.2517&partnerID=40&md5=7ffe6fd23a5840898922acac18df4400","A case of daytime development of deep convection over tropical semi-arid land is used to evaluate the representation of convection in global and regional models. The case is based on observations collected during the African Monsoon Multidisciplinary Analysis (AMMA) field campaign and includes two distinct transition phases, from clear sky to shallow cumulus and from cumulus to deep convection. Different types of models, run with identical initial and boundary conditions, are intercompared: a reference large-eddy simulation (LES), single-column model (SCM) version of four different Earth system models that participated in the Coupled Model Intercomparison Project 5 exercise, the SCM version of the European Centre for Medium-range Weather Forecasts operational forecast model, the SCM version of a mesoscale model and a bulk model. Surface fluxes and radiative heating are prescribed preventing any atmosphere-surface and cloud-radiation coupling in order to simplify the analyses so that it focuses only on convective processes. New physics packages are also evaluated within this framework. As the LES correctly reproduces the observed growth of the boundary layer, the gradual development of shallow clouds, the initiation of deep convection and the development of cold pools, it provides a basis to evaluate in detail the representation of the diurnal cycle of convection by the other models and to test the hypotheses underlying convective parametrizations. Most SCMs have difficulty in representing the timing of convective initiation and rain intensity, although substantial modifications to boundary-layer and deep-convection parametrizations lead to improvements. The SCMs also fail to represent the mid-level troposphere moistening during the shallow convection phase, which we analyse further. Nevertheless, beyond differences in timing of deep convection, the SCM models reproduce the sensitivity to initial and boundary conditions simulated in the LES regarding boundary-layer characteristics, and often the timing of convection triggering. © 2015 Royal Meteorological Society."
"6602444277;55745772700;55745457300;55745806400;55746438300;55745388500;55746213100;7005798946;55745933000;55746100000;55745329500;55746309400;51161295700;","Tropical cloud cluster climatology, variability, and genesis productivity",2013,"10.1175/JCLI-D-12-00387.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84878141969&doi=10.1175%2fJCLI-D-12-00387.1&partnerID=40&md5=efccfbdc42945f99b808241448dd0989","Tropical cloud clusters (TCCs) are traditionally defined as synoptic-scale areas of deep convection and associated cirrus outflow. They play a critical role in the energy balance of the tropics, releasing large amounts of latent heat high in the troposphere. If conditions are favorable, TCCs can develop into tropical cyclones (TCs), which put coastal populations at risk. Previous work, usually connected with large field campaigns, has investigated TCC characteristics over small areas and time periods. Recently, developments in satellite reanalysis and global best track assimilation have allowed for the creation of a much more extensive database of TCC activity. The authors use the TCC database to produce an extensive global analysis of TCCs, focusing on TCC climatology, variability, and genesis productivity (GP) over a 28-yr period (1982-2009). While global TCC frequency was fairly consistent over the time period, with relatively small interannual variability and no noticeable trend, regional analyses show a high degree of interannual variability with clear trends in some regions. Approximately 1600 TCCs develop around the globe each year; about 6.4% of those develop into TCs. The eastern North Pacific Ocean (EPAC) basin produces the highest number of TCCs (per unit area) in a given year, but the western North Pacific Ocean (WPAC) basin has the highest GP (;12%). Annual TCC frequency in some basins exhibits a strong correlation to sea surface temperatures (SSTs), particularly in the EPAC, North Atlantic Ocean, and WPAC. However, GP is not as sensitive to SST, supporting the hypothesis that the tropical cyclogenesis process is most sensitive to atmospheric dynamical considerations such as vertical wind shear and large-scale vorticity. © 2013 American Meteorological Society."
"21739916500;24779895300;26433635200;7103280079;25226189300;6603812137;","High-speed video of lightning and x-ray pulses during the 2009-2010 observation campaigns in northeastern Spain",2012,"10.1016/j.atmosres.2011.09.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84865655743&doi=10.1016%2fj.atmosres.2011.09.013&partnerID=40&md5=25811c1b657c8c73c2d7bab4c933a089","This paper summarizes results obtained by the 2009-2010 field campaigns conducted in northeastern Spain using a high speed camera, VHF interferometer, VLF lightning location system and scintillation detectors for energetic radiation. The main purpose was to obtain new insight into the lightning processes which emit x/γ radiation. For just one (very close) lightning strike, 99 x-ray pulses were emitted within 0.86. ms and had an energy higher that 10. keV. This burst was associated with the final stages of a downward negative leader. The high-speed camera data also allowed to identify various previously unreported features in different types of cloud-to-ground lightning flashes. At video frame rates of 10,000. fps, some branches of negative leaders of cloud-to-ground flashes were illuminated for the duration of only one frame. During positive cloud-to-ground flashes, the high speed videos showed an intense activity of recoil leaders. In the case of intra-cloud lightning, the VHF interferometer network did not present a clear relation between detections and visible leader. Instead, bursts of VHF detections corresponded visually to a long-lasting bright channel under the cloud base. © 2011 Elsevier B.V."
"23995016900;6701590980;","A numerical study of the evolving convective boundary layer and orographic circulation around the santa catalina mountains in Arizona. Part II: Interaction with deep convection",2010,"10.1175/2010MWR3318.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77958456210&doi=10.1175%2f2010MWR3318.1&partnerID=40&md5=512d9c4c4c4cfe05c27f00efcfbd8647","This is the second part of a study that examines the daytime evolution of the thermally forced boundary layer (BL) circulation over a relatively isolated mountain, about 30 km in diameter and 2 km high, and its interaction with locally initiated deep convection by means of numerical simulations validated with data collected in the 2006 Cumulus Photogrammetric, In Situ, and Doppler Observations (CuPIDO) field campaign in southeastern Arizona. Part I examined the BL circulation in cases with, at most, rather shallow orographic cumulus (Cu) convection; the present part addresses deep convection. The results are based on output from version 3 of the Weather Research and Forecasting model run at a horizontal resolution of 1 km. The model output verifies well against CuPIDO observations. In the absence of Cu convection, the thermally forced (solenoidal) circulation is largely contained within the BL over the mountain. Thunderstorm development deepens this BL circulation with inflow over the depth of the BL and outflow in the free troposphere aloft. Primary deep convection results from destabilization over elevated terrain and tends to be triggered along a convergence line, which arises from the solenoidal circulation but may drift downwind of the terrain crest. While the solenoidal anabatic flow converges moisture over the mountain, it also cools the air. Thus, a period of suppressed anabatic flow following a convective episode, at a time when surface heating is still intense, can trigger new and possibly deeper convection. The growth of deep convection may require enhanced convergent flow in the BL, but this is less apparent in the mountain-scale surface flow signal than the decay of orographic convection. A budget study over the mountain suggests that the precipitation efficiency of the afternoon convection is quite low, ~ 10% in this case. © 2010 American Meteorological Society."
"7003854090;7102062952;41561458500;7004139928;22036936800;","Natural volatile organic compound emissions from plants and their roles in oxidant balance and particle formation",2009,"10.1029/2008GM000717","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79959420818&doi=10.1029%2f2008GM000717&partnerID=40&md5=bb50f43208e6e5d6b9acdeaff9befb18","Numerous biogenic volatile organic compounds (VOC) species are released into the atmosphere from tropical forests. Measuring all those which are relevant for atmospheric chemistry or for the carbon budget is challenging. Large-Scale Biosphere-Atmosphere (LBA) Experiment field campaigns substantially increased the number of field studies of isoprene and monoterpene emissions, as well as of the exchange of several other VOC species. This chapter reports about the progress made within LBA from primary emission measurements at the plant species level up to discussions of the oxidative capacity of the atmosphere and formation of secondary organic aerosol particles and cloud condensation nuclei from biogenic hydrocarbons. VOC emission from Amazonian ecotypes has strong effects on atmospheric chemistry, which are obviously not fully understood in the case of the tropical atmosphere. Atmospheric flux studies within numerous field experiments resulted in new knowledge about local to regional scale biogenic VOC exchange and improved modeling. New data obtained from field as well as from laboratory studies helped to characterize VOC emissions from the Amazonian forest underlying seasonality within dry and wet seasons. Furthermore, first insight was obtained into the potential of floodplain areas affected by long-lasting flooding periods which can cause special emission adaptation. © Copyright 2009 by the American Geophysical Union."
"57201410408;6701569731;","Early observations of rotor clouds by Andrija Mohorovičić",2007,"10.1175/BAMS-88-5-693","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250852921&doi=10.1175%2fBAMS-88-5-693&partnerID=40&md5=54f315ed8a78dcf9e2168a7cbc2fda3d","This article delivers a short history of the early quantitative documentation of a rotor-type circulation in the bora-type flow on the northern Adriatic by Andrija Mohorovičić, an all-around geophysicist and the father of Croatian geophysical research who is widely known as the discoverer of discontinuity between the Earth's crust and mantle. This historical work presents an overview of Mohorovičć's research technique and rotor-related contributions, together with a short account of other observations of rotors contemporary to Mohorovičić as well as those from the 1920s and 1930s, considered to be seminal work on the subject on atmospheric rotors to date. In the year that marks the 150th anniversary of Mohorovičić's birth, his early meteorological observations remain germane for atmospheric rotor research, which is currently experiencing a renaissance with the Terrain-Induced Rotor Experiment (T-REX), a recently completed international field campaign and an ongoing research effort focused on atmospheric terrain-induced rotors. © 2007 American Meteorological Society."
"14045744500;7103293742;7006728825;6507690692;7402579146;7006617518;7101691582;6602310241;","Secondary initiation of multiple bands of cumulonimbus over southern Britain. I: An observational case-study",2006,"10.1256/qj.05.151","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746239484&doi=10.1256%2fqj.05.151&partnerID=40&md5=b64d6261d9df9504dadb4095400d359a","Special observing facilities have been assembled in southern England as part of the Convective Storm Initiation Project (CSIP) to study the mesoscale and convective-scale processes that determine precisely where warm-season convective showers will break out. This paper reports the results of a case-study during the pilot field campaign of CSIP in July 2004. One purpose of the pilot project was to demonstrate the value of various observational facilities and to evaluate the usefulness of a variety of analysis and synthesis techniques. Amongst other things, the case-study demonstrates the utility of high-resolution imagery from the Meteosat Second Generation satellite for tracking the early stages of the convective clouds, and of a new clear-air scanning radar at Chilbolton for mapping both the top of the boundary layer and the initial growth of the convective cells that penetrate it. The particular event studied involved the triggering of convection that developed into three parallel arcs of showers and thunderstorms. The first arc was triggered along the leading edge of the outflow (density current) from an earlier cluster of showers, but the convection in the second and third arcs was triggered by a different mechanism. The paper describes in detail the way in which this convection broke through the stable layer, or lid, at the top of a boundary layer of variable depth. The strength of the lid decreased and the depth of the boundary layer increased with time as a result of diurnal heating, but the precise locations where convection finally broke through were determined by the spatial variability in boundary-layer depth. The analysis suggests that a wave-like modulation of the boundary-layer depth of amplitude 150 m, perhaps due to a gravity-wave disturbance from the earlier cluster of showers, had a greater influence on where the convection was triggered than the modest hills (typically 200 m high) in southern England. © Royal Meteorological Society, 2006. The contribution of P. A. Clark is Crown copyright."
"7004613032;55954833500;7403204849;7003720206;7004538458;7004510293;7006495018;56256037700;7402655282;57195355942;","INTERCOMP2000: Ionic constitution and comparison of filter and impactor",2004,"10.1016/j.atmosenv.2004.08.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-7444233827&doi=10.1016%2fj.atmosenv.2004.08.029&partnerID=40&md5=9e9f5d7f7d20687b57a4c19b2b37efbc","The field campaign INTERCOMP2000 was organised within the EUROTRAC-2 subproject AEROSOL for characterisation of aerosol at a rural site. The groups involved used a wide range of measurement methods for aerosol particles. Although the focus was on critical aerosol properties like mass, nitrate and carbon, in this paper particular attention is given to the role of inorganic soluble material being main part of the cloud condensation nuclei. Here, we compare methods used in Europe also for inorganic ion mass concentrations: three high-volume samplers (2 Digitel and 1 Sierra Andersen, equipped with quartz fibre filters), four low-volume samplers (1 Rupprecht Patashnik with Teflon filter; 3 stacked filter units with Teflon, cellulose ester or Whatman 41 filter), and 2 low-pressure impactors (Berner type with Tedlar foils). Ten parallel 24 h samples were compared. The data for the main ions nitrate, sulphate and ammonium agree well for the PM10 as well for PM2.5 aerosol fraction; relative standard deviation of about 20-40% were found. The single values for calcium, sodium and chloride which contribute only minor to the soluble inorganic mass scatter very strongly around the calculated averages: about 50% in PM10 mode, and even 100% in PM2.5 mode. While laboratory calibrations typically indicate performance close to design specifications, methods during field operation are subject to a number of sampling and handling artefacts. We know that the different sampling principles used in this study, and the analytical procedures done by each group with their own methodology will cause a main part of the observed uncertainties. In reality, due to different reasons (availability, costs, manpower, different analysis from the same sample, size and time resolution, etc) in many networks and field studies a high variability of methods for aerosol characterisation is used and often those experimental figures will be used for statistical interpretations. Thus, our paper will emphasise that harmonisation among different PM measurements is the ""order of the day"". © 2004 Elsevier Ltd. All rights reserved."
"6603420709;7102745183;","High-resolution short-term quantitative precipitation forecasting in mountainous regions using a nested model",1999,"10.1029/1999JD900938","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033611338&doi=10.1029%2f1999JD900938&partnerID=40&md5=c0f5e5603639870c0a12848ff16da731","In mountainous regions, the spatial and temporal distribution of precipitation is strongly influenced by local orography. The resolution of operational numerical weather prediction (NWP) models has been enhanced significantly in recent years but has yet to reach the level necessary to capture fully the influences of high-relief topography on precipitation and flow dynamics. Furthermore, the parameterizations of precipitation mechanisms and cloud microphysics in these models have been developed on the basis of observational and field campaigns generally carried out far away from complex terrain and thus may not represent the physics associated with orographic precipitation. Here we attempt to address both issues by nesting a small-scale physically based orographic precipitation model (OPM) at 1-km resolution within the fifth-generation Penn State/National Center for Atmospheric Research Mesoscale Model (PSU/NCAR MM5) at 12-km resolution. This approach is investigated by simulating six storms in the Pocono Mountains of Pennsylvania. Some improvement over the MM5 was achieved, such as an increase in hourly threat score. The reliability of the MM5 and OPM forecasts for more intense, less frequent events (exceeding 4 mm/h) was shown to be significant, through the threat scores for these amounts indicate a need for additional improvement. This study suggests that further improvements in nested modeling applications are constrained by the degree to which the host model can provide boundary and initial conditions that represent the actual state of the atmosphere. One possible solution for this problem is the adaptive assimilation of remotely sensed data to provide initial and updated moisture and temperature fields throughout a forecast period. Copyright 1999 by the American Geophysical Union."
"7005174340;","A quantitative comparison of ground-based FSSP and PVM measurements",1998,"10.1175/1520-0426(1998)015<0887:AQCOGB>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032453271&doi=10.1175%2f1520-0426%281998%29015%3c0887%3aAQCOGB%3e2.0.CO%3b2&partnerID=40&md5=4c7e50bc5192eafa57f202b456d4a06e","Cloud microphysical measurements of two ground-based field campaigns are analyzed in order to compare Particle Volume Monitor (PVM) measurements and Forward Scattering Spectrometer Probe (FSSP)-derived integrated quantities (mainly liquid water content LWC) for different types of drop size distributions. It is shown that in case of size distributions containing mostly small drops with diameters D < 25 μm the PVM and FSSP measurements agree if respective data corrections (activity and changing VAR, Mie curve adjustment, and wind ramming) are applied to the FSSP raw data. Therefore, it is concluded that both PVM and FSSP are excellent microphysical sensors in continental, stratiform, or cumuliform clouds with mostly small drops. However, if low concentrations of large drops (D > 25 μm) are present in the drop size distribution, which considerably increases LWC, discrepancies between PVM and FSSP measurements are established. The most likely explanation for the differences is that the sensitivity of the PVM decreases for low drop concentrations."
"7402846120;22235086500;6506910066;7003891764;7005459266;8074824500;7003664518;","The amazon floodplain through radar eyes: Lago grande de monte alegre case study",1998,"10.1080/07038992.1998.10874698","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001130314&doi=10.1080%2f07038992.1998.10874698&partnerID=40&md5=c5753fd4400f1eb35a014e3ff6178fd2","There is a lack of information on the seasonal changes in the floodplain habitat in the Amazon regions of Brazil. This lack of information is due to the large size of the Amazon, persistent cloud cover and difficult access for field campaigns. Satellite radar sensors can provide multitemporal images over these cloudy tropical regions which can result in better mapping of the extent of the floodplain habitat. This research shows the synergism multi-frequency and multi-incidence angle radar data for studying the Amazon floodplain. RADARSAT and JERS-1 images were acquired on May 1996 for the Lago Grande test site in Brazil. The acquisitions coincide with the high water period of the hydrological cycle of the region of study. The images were calibrated, ortho-rectified and filtered allowing for the integration and classification of the data. The results show that the synergism of multi-frequency (C- and L- band) data provides a better combination of microwave information to discriminate among the floodplain habitat. C-band data is more sensitive to aquatic plants and water whereas L-band data is more effective in distinguishing between flooded forest and aquatic plants, and non-flooded forest and pasture. The combination of the two wavelengths increased the separability of the different classes. © 1998, Taylor & Francis Group, LLC. All rights reserved."
"56577620100;56060986400;57200071023;16444265000;6603868770;24331295800;6603697954;35867336200;8909993500;6507296473;57194110395;6701832491;57004829200;7103204204;7003922583;6508213402;57190209035;","Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017",2018,"10.5194/acp-18-17995-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058956453&doi=10.5194%2facp-18-17995-2018&partnerID=40&md5=8e7eb1566fdf0b8252394c8a45bf006a","The two concerted field campaigns, Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) and the Physical feedbacks of Arctic planetary boundary level Sea ice, Cloud and AerosoL (PASCAL), took place near Svalbard from 23 May to 26 June 2017. They were focused on studying Arctic mixed-phase clouds and involved observations from two airplanes (ACLOUD), an icebreaker (PASCAL) and a tethered balloon, as well as ground-based stations. Here, we present the synoptic development during the <span classCombining double low line""inline-formula 35-day period of the campaigns, using near-surface and upper-air meteorological observations, as well as operational satellite, analysis, and reanalysis data. Over the campaign period, short-term synoptic variability was substantial, dominating over the seasonal cycle. During the first campaign week, cold and dry Arctic air from the north persisted, with a distinct but seasonally unusual cold air outbreak. Cloudy conditions with mostly low-level clouds prevailed. The subsequent 2 weeks were characterized by warm and moist maritime air from the south and east, which included two events of warm air advection. These synoptical disturbances caused lower cloud cover fractions and higher-reaching cloud systems. In the final 2 weeks, adiabatically warmed air from the west dominated, with cloud properties strongly varying within the range of the two other periods. Results presented here provide synoptic information needed to analyze and interpret data of upcoming studies from ACLOUD/PASCAL, while also offering unprecedented measurements in a sparsely observed region. © 2018 Author(s)."
"36465445700;8853393600;57204983024;56798586300;55682751100;36932778600;36461484800;6603615831;57203404693;8546957800;23024216600;57202066728;","CLEPS 1.0: A new protocol for cloud aqueous phase oxidation of VOC mechanisms",2017,"10.5194/gmd-10-1339-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016482084&doi=10.5194%2fgmd-10-1339-2017&partnerID=40&md5=2575f39a002d01bace9512f9c60546a2","A new detailed aqueous phase mechanism named the Cloud Explicit Physico-chemical Scheme (CLEPS 1.0) is proposed to describe the oxidation of water soluble organic compounds resulting from isoprene oxidation. It is based on structure activity relationships (SARs) which provide global rate constants together with branching ratios for HO abstraction and addition on atmospheric organic compounds. The GROMHE SAR allows the evaluation of Henry's law constants for undocumented organic compounds. This new aqueous phase mechanism is coupled with the MCM v3.3.1 gas phase mechanism through a mass transfer scheme between gas phase and aqueous phase. The resulting multiphase mechanism has then been implemented in a model based on the Dynamically Simple Model for Atmospheric Chemical Complexity (DSMACC) using the Kinetic PreProcessor (KPP) that can serve to analyze data from cloud chamber experiments and field campaigns. &lt;br&gt;&lt;br&gt; The simulation of permanent cloud under low-NOx conditions describes the formation of oxidized monoacids and diacids in the aqueous phase as well as a significant influence on the gas phase chemistry and composition and shows that the aqueous phase reactivity leads to an efficient fragmentation and functionalization of organic compounds. © 2017 The Author(s)."
"25924878400;57193132723;7404829395;56003457200;","An improved convective ice parameterization for the NASA GISS global climate model and impacts on cloud ice simulation",2017,"10.1175/JCLI-D-16-0346.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008226088&doi=10.1175%2fJCLI-D-16-0346.1&partnerID=40&md5=3cac6d168b629b23fe4e9366d087d3f4","Partitioning of convective ice into precipitating and detrained condensate presents a challenge for GCMs since partitioning depends on the strength and microphysics of the convective updraft. It is an important issue because detrainment of ice from updrafts influences the development of stratiform anvils, impacts radiation, and can affect GCM climate sensitivity. Recent studies have shown that the CMIP5 configurations of the Goddard Institute for Space Studies (GISS) GCM simulated upper-tropospheric ice water content (IWC) that exceeded an estimated upper bound by a factor of 2. Partly in response to this bias, a new GCM parameterization of convective cloud ice has been developed that incorporates new ice particle fall speeds and convective outflow particle size distributions (PSDs) from the NASA African Monsoon Multidisciplinary Analyses (NAMMA), NASA Tropical Composition, Cloud and Climate Coupling (TC4), DOE ARM-NASA Midlatitude Continental Convective Clouds Experiment (MC3E), and DOE ARM Small Particles in Cirrus (SPARTICUS) field campaigns. The new parameterization assumes a normalized gamma PSD with two novel developments: no explicit assumption for particle habit in the calculation of mass distributions, and a formulation for translating ice particle fall speeds as a function of maximum diameter into fall speeds as a function of melted-equivalent diameter. Two parameters (particle volume- and projected area-weighted equivalent diameter) are diagnosed as a function of temperature and IWC in the convective plume, and these parameters constrain the shape and scale of the normalized gamma PSD. The diagnosed fall speeds and PSDs are combined with the GCM's parameterized convective updraft vertical velocity to partition convective updraft condensate into precipitating and detrained components. A 5-yr prescribed sea surface temperature GCM simulation shows a 30%-50% decrease in upper-tropospheric deep convective IWC, bringing the tropical and global mean ice water path into closer agreement with CloudSat best estimates. © 2017 American Meteorological Society."
"23967739600;55895104800;9940496700;","High-resolution doppler lidar observations of transient downslope flows and rotors",2013,"10.1175/MWR-D-12-00260.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884911612&doi=10.1175%2fMWR-D-12-00260.1&partnerID=40&md5=3b056e09e0818d4f7b4a80ef3ed5245b","The authors present observations of the temporal evolution of downslope windstorms with rotors and internal hydraulic jumps of unprecedented detail and spatiotemporal coverage. The observations were carried out by means of a coherent Doppler lidar in the lee of the southern Sierra Nevada range during the sixth intensive observational period of the Terrain-induced Rotor Experiment (T-REX) in 2006. Two representative flow regimes are analyzed and juxtaposed in this paper. The first case shows pulses of high-momentum air that propagate eastward through the valley with an internal hydraulic jump on the leading edge. The region downstream of the transient internal hydraulic jump is characterized by turbulence but no coherent rotor circulation was observed. During the second case, the strongest windstorm of the field campaign T-REX occurred. The observed features of this event resemble the classical notion of a rotor. Altogether, the Doppler lidar observations of both downslope flow events reveal a complex, turbulent flow that is highly transient, intermittent, 3D, and interacts with a significant along-valley flow. © 2013 American Meteorological Society."
"8658853400;6701538799;57195881858;","Numerical simulation of episodes of organized convection in tropical Northern Africa",2012,"10.1175/MWR-D-11-00330.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84867976222&doi=10.1175%2fMWR-D-11-00330.1&partnerID=40&md5=66409c32f4cc5ef535613e0c36d72327","A large-domain convection-permitting numerical model is used to simulate episodes of deep convection, which are generated during the day over the Ethiopian Highlands and then propagate westward over the eastern and central Sahel region (5°-20°N) of northern Africa. The simulation comprises 12.5 days within the African Monsoon Multidisciplinary Analysis (AMMA) field campaign in 2006. During this period, long-lived precipitation episodes that survived beyond a single diurnal cycle occurred in the lee of the Ethiopian Highlands only every 2-3 days in both the simulation and observations. This contrasts with some other latitudinal corridors in the lee of major topography, such as the central United States, where long-lived heavy precipitation episodes frequently occur on successive nights. The intermittency of long-lived events for the current case occurs despite regular daily triggering of convection along the upstream orography, and is linked to strong lower-tropospheric stabilization and reduction of daytime surface sensible heat flux due to residual cloudiness in the wake of long-lived precipitation events during the previous diurnal cycle. The vertical shear that helps organize deep convection is also weakened in the wake of the long-lived events by temporary disruptions of the midtropospheric African easterly jet. The environments of mesoscale convection are presented for the eastern Sahel, a region where most Sahelian convection originates, but about which little is known at the mesoscale. The study describes the potential for early identification of long-lived convection episodes that are likely to have high impact on the central Sahel and West Africa. © 2012 American Meteorological Society."
"55714142500;","Comparison of atmospheric infrared sounder temperature and relative humidity profiles with NASA African Monsoon Multidisciplinary Analyses (NAMMA) dropsonde observations",2009,"10.1029/2009JD012083","https://www.scopus.com/inward/record.uri?eid=2-s2.0-72049126132&doi=10.1029%2f2009JD012083&partnerID=40&md5=592a17f6e81ce8868972f6fe667e257a","The 2006 NASA African Monsoon Multidisciplinary Analyses (NAMMA) field campaign was conducted to investigate the Saharan Air Layer (SAL) activity and its influence on Atlantic tropical cyclones. During the field campaign, 197 dropsonde soundings were collected from 13 research flights over the eastern Atlantic (10°N-22°N, 16°W-34°W) between 19 August and 12 September 2006 which provide a valuable data set to examine the uncertainty of the temperature and relative humidity profiles retrieved from the Atmospheric Infrared Sounder (AIRS) data in the SAL region. Comparing AIRS retrievals with the dropsonde observations indicates that AIRS profiles have a RMS difference of 1.35°C in temperature at the eight standard pressure levels and a RMS difference of 13.8% in relative humidity on seven standard pressure layers from 1000 hPa to 300 hPa. In particular, the RMS differences of temperature and relative humidity range from 0.79°C to 1.61°C and from 10.1% to 15.3%, respectively, from 1000 hPa to 300 hPa. Note that the uncertainty is estimated under sky conditions with active cloud activity because many NAMMA dropsondes were released in the cloud clusters or in the circulation of named tropical cyclones. This study suggests that in the SAL or the region with cloud activity the AIRS relative humidity/temperature has the RMS error within/ approaching the design expectation for clear sky conditions. Copyright 2009 by the American Geophysical Union."
"26667390100;8728807200;7005793536;7003574171;56230578500;7003956042;6602403409;7006813055;7003495004;51561863100;7004022660;6603034566;6507472270;6603688422;10243516400;55886067800;57202531041;7006253164;7102580610;8551312700;55944611200;36807959100;7201438966;6602296992;6506271794;6508190640;6507400087;7402883211;7005174340;57196781688;","Influence of clouds on the spectral actinic flux density in the lower troposphere (INSPECTRO): Overview of the field campaigns",2008,"10.5194/acp-8-1789-2008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-41249087135&doi=10.5194%2facp-8-1789-2008&partnerID=40&md5=e21f6a66e748f4dacd13bcda065f78a4","Ultraviolet radiation is the key factor driving tropospheric photochemistry. It is strongly modulated by clouds and aerosols. A quantitative understanding of the radiation field and its effect on photochemistry is thus only possible with a detailed knowledge of the interaction between clouds and radiation. The overall objective of the project INSPECTRO was the characterization of the three-dimensional actinic radiation field under cloudy conditions. This was achieved during two measurement campaigns in Norfolk (East Anglia, UK) and Lower Bavaria (Germany) combining space-based, aircraft and ground-based measurements as well as simulations with the one-dimensional radiation transfer model UVSPEC and the three-dimensional radiation transfer model MYSTIC. During both campaigns the spectral actinic flux density was measured at several locations at ground level and in the air by up to four different aircraft. This allows the comparison of measured and simulated actinic radiation profiles. In addition satellite data were used to complete the information of the three dimensional input data set for the simulation. A three-dimensional simulation of actinic flux density data under cloudy sky conditions requires a realistic simulation of the cloud field to be used as an input for the 3-D radiation transfer model calculations. Two different approaches were applied, to derive high- and low-resolution data sets, with a grid resolution of about 100 m and 1 km, respectively. The results of the measured and simulated radiation profiles as well as the results of the ground based measurements are presented in terms of photolysis rate profiles for ozone and nitrogen dioxide. During both campaigns all spectroradiometer systems agreed within ±10% if mandatory corrections e.g. stray light correction were applied. Stability changes of the systems were below 5% over the 4 week campaign periods and negligible over a few days. The J(O1D) data of the single monochromator systems can be evaluated for zenith angles less than 70°, which was satisfied by nearly all airborne measurements during both campaigns. The comparison of the airborne measurements with corresponding simulations is presented for the total, downward and upward flux during selected clear sky periods of both campaigns. The compliance between the measured (from three aircraft) and simulated downward and total flux profiles lies in the range of ±15%."
"6603196991;6603873829;6507128092;22133985200;57206330745;","Accuracy assessment of an integrated profiling technique for operationally deriving profiles of temperature, humidity, and cloud liquid water",2007,"10.1029/2006JD007379","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34848877242&doi=10.1029%2f2006JD007379&partnerID=40&md5=fc01ec01c6410b0249e59a438aa7ea5c","An integrated profiling technique (IPT) for the simultaneous retrieval of the atmospheric state parameters temperature, humidity, and liquid water content profiles is assessed. The method combines measurements of a modern, ground-based profiling station equipped with a microwave profiler, cloud radar, and ceilometer, with the closest operational radiosonde measurement and standard surface-based meteorological measurements. All are combined within an optimal estimation procedure. The accuracy assessment is carried out in a virtual environment of a regional climate model. The model thermodynamic state is converted into the measurement space via so-called forward modeling. The IPT is then applied to the simulated measurements to retrieve the desired atmospheric state parameters which can be evaluated with the original model state. It is found that IPT-derived temperature and humidity profiles can add significant information for the time period between two operational radiosonde ascents, both if the measurements take place at the radiosonde site or if they are spatially apart. The benefits of a profiling station that applies an IPT can be valuable both for the reprocessing of dedicated field campaign data to obtain the best representation of the atmospheric state and for nowcasting and data assimilation applications. Depending on the density of the given operational radiosonde network, a ground-based profiling station has the potential of either significantly improving the quality of such a network or even substituting a small number of radiosonde stations. A further benefit of a ground-based profiling station is the retrieval of cloud microphysical properties, where IPT liquid water path retrieval accuracies show values better than 10 g m-2, and liquid water content profiles can be derived with relative accuracies of ∼30%. Copyright 2007 by the American Geophysical Union."
"9537045600;35608308400;7004167838;","Evaluation of radar multiple-scattering effects from a GPM perspective, Part II: Model results",2006,"10.1175/JAM2425.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846254052&doi=10.1175%2fJAM2425.1&partnerID=40&md5=4d205dceb2e9fda184e7d4582e1ebfe0","Multiple-scattering effects as sensed by radars in configurations useful in the context of the Global Precipitation Mission (GPM) are evaluated for a range of meteorological profiles extracted from four different cloud-resolving model simulations. The multiple-scattering effects are characterized in terms of both the reflectivity enhancement and the linear depolarization ratio. When considering the copolarized reflectivity in spaceborne configurations, the multiple-scattering enhancement becomes a real issue for Ka-band radars, though it is generally negligible at the Ku band, except in meteorologically important situations such as when high rain rates and a considerable amount of ice are present aloft. At Ka band it can reach tens of decibels when systems of heavy cold rain are considered, that is, profiles that include rain layers with high-density ice particles aloft. On the other hand, particularly at 35 GHz, high values of the linear depolarization ratio are predicted even in airborne configurations because of multiple-scattering effects. This result should allow the observation of these features in field campaigns. © 2006 American Meteorological Society."
"35612968400;7201832531;7003762067;7103246957;","Daytime cycle of low-level clouds and the tropical convective boundary layer in southwestern Amazonia",2005,"10.1175/JAM2266.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-28144431689&doi=10.1175%2fJAM2266.1&partnerID=40&md5=3f86da3190ceec2406a3d2ca9e6b00ae","During the wet season in the southwestern Amazon region, daytime water transport out of the atmospheric mixed layer into the deeper atmosphere is shown to depend upon cloud amounts and types and synoptic-scale velocity fields. Interactions among clouds, convective conditions, and subcloud-layer properties were estimated for two dominant flow regimes observed during the 1999 Tropical Rainfall Measuring Mission component of the Brazilian Large-Scale Biosphere-Atmosphere (TRMM-LBA) field campaign. During daytime the cloud and subcloud layers were coupled by radiative, convective, and precipitation processes. The properties of cloud and subcloud layers varied according to the different convective influences of easterly versus westerly lower-tropospheric flows. The most pronounced flow-regime effects on composite cloud cycles occurred under persistent lower-tropospheric flows, which produced strong convective cloud growth with a near absence of low-level stratiform clouds, minimal cumulative attenuation of incoming solar irradiance (∼25%), rapid daytime mixed-layer growth (&gt;100 m h-1), and boundary layer drying (0.22 g kg-1 h-1), high convective velocities (&gt;1.5 m s-1), high surface buoyancy flux (&gt;200 W m-2), and high latent heat flux (600 W m-2) into cloud layer. In contrast, persistent westerly flows were less convective, showing a strong morning presence of low-level stratiform genera (&gt;0.9 cloud amount), greater cumulative attenuation of incoming solar irradiance (∼47%), slower mixed-layer growth (&lt;50 m h-1) with a slight tendency for mixed-layer moistening, and a delayed peak in the low-level cumuliform cloud cycle (2000 versus 1700 UTC). The results reported in this article indicate that numerical models need to account for cloud amounts and types when estimating water vapor transport to the cloud layer. © 2005 American Meteorological Society."
"7409080503;8839875600;6603742681;","Impact of surface inhomogeneity on solar radiative transfer under overcast conditions",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448957624&partnerID=40&md5=d680bff79df2e1c424cae1a5b7f00623","The goal of this study was to assess the ability of the Moderate-Resolution Transmittance 4 (MODTRAN-4) code to simulate high-resolution shortwave (SW) fluxes given detailed and complete input information under overcast conditions. The study underlines the impact of surface inhomogeneity on the closure of SW radiative transfer. It also leads to a method of estimating surface spectral areal-mean albedo from downwelling solar transmittance measurements. The investigation made use of ample Atmospheric Radiation Measurement (ARM) field data collected by a suite of instruments, including broadband and narrowband radiometers and spectrometers, cloud radar and lidar, microwave radiometer, atmospheric sounding instruments, and satellite data. Furnishing the MODTRAN-4 code with observed atmospheric, cloud, and surface parameters generates spectral solar transmittance at the surface and reflectance at the top of the atmosphere (TOA). The transmittances were compared with the Rotating Shadowband Spectroradiometer measurements and showed significant discrepancies in the near-infrared (NIR) region, the bulk of which was attributed to the use of unrepresentative surface spectral albedos. A field campaign was undertaken to collect surface albedo data for a wide variety of land cover types near the ARM Central Facility. The sampled data were combined with thematic mapper/Landsat-based land cover classification data to map surface spectral albedo. Substitution of the derived areal-mean spectral albedo into the MODTRAN-4 model eliminates major discrepancies in the NIR, and also leads to good agreements with surface solar broadband fluxes and TOA satellite spectral reflectance. On the basis of these findings, one may use downwelling spectral transmittance data, together with detailed cloud and atmospheric information, to estimate surface effective areal-mean albedo. The estimated values agree well with those derived from the ground survey data. Following the method, a data set of effective areal-mean spectral albedo throughout a year was obtained. Copyright 2002 by the American Geophysical Union."
"7005297959;7006519716;7003482993;6507143686;7006107059;7004101548;56187256200;57205954997;6603755619;6507544909;7003679125;7004041753;6508220771;","The BAYSOFI campaign - Measurements carried out during the total solar eclipse of August 11, 1999",2001,"10.1127/0941-2948/2001/0010-0165","https://www.scopus.com/inward/record.uri?eid=2-s2.0-17844381301&doi=10.1127%2f0941-2948%2f2001%2f0010-0165&partnerID=40&md5=0e108c9819cceabcb69c7504938a27f5","The total solar eclipse of August 11, 1999 provided a unique opportunity to observe the input of fast day-night and night-day transitions, under high solar elevation around noon, on the earth-atmosphere-biosphere system. Within the interdisciplinary field campaign BAYSOFI, measurements of radiation, boundary layer micrometeorology and photochemistry, photosynthesis and transpiration were carried out at Freising-Weihenstephan and several locations nearby focusing on short-term effects of the eclipse. Although the overall grosswetterlage on August 11 was not favourable for viewing the eclipse, with clouds covering most of central Europe, observational conditions at Weihenstephan were fair due to a large hole in the cloud layer which appeared just half hour before totality lasting for more than one hour. Thus significant effects of the eclipse on radiation, photolysis rates, OH, the temperature, wind, turbulence structure and stratification, ozone and CO2 fluxes, photosynthesis, transpiration and sap flow of trees could be observed which are reported and discussed in the following sequence of papers."
"7005287667;7102496779;7003566416;7003748130;7004462114;57214957433;7006595513;7005174340;7003377899;57203079636;7004191948;6603393151;6602412038;7005228425;24545697300;7006655217;6701610867;55954833500;56506988700;35477504600;6701336868;7005601996;7004015298;7006354036;7404957330;7003717370;","Source identification during the Great Dun Fell Cloud Experiment 1993",1997,"10.1016/S1352-2310(96)00178-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030616212&doi=10.1016%2fS1352-2310%2896%2900178-1&partnerID=40&md5=c956d245d1fc0c4dc3c8ff6642f3b812","A characterisation of the sources influencing the site for the final field campaign of the EUROTRAC subproject GCE (Ground-based Cloud Experiment) at Great Dun Fell, Cumbria, Great Britain in April-May 1993 is presented. The sources were characterised mainly by means of aerosol filter and cascade impactor data, single particle analysis, gas data, data on aromatic organic compounds, cloud water ionic composition, measurements of aerosol size distributions and hygroscopic properties and various meteorological information. Receptor models applied on the aerosol filter and impactor data sets separately revealed two major source types being a marine sea spray source and a long-range transported anthropogenic pollution source. The results of the receptor models were largely consistent with the other observations used in the source identification. Periods of considerable anthropogenic pollution as well as almost pure marine air masses were clearly identified during the course of the experiment."
"24436112500;6701837713;8963601100;56954893300;55190998900;57196147885;57204744715;57196146725;7203075090;6601980778;24458137900;","Variations in surface ozone and carbon monoxide in the Kathmandu Valley and surrounding broader regions during SusKat-ABC field campaign: Role of local and regional sources",2018,"10.5194/acp-18-11949-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051983278&doi=10.5194%2facp-18-11949-2018&partnerID=40&md5=168326fe81b3e0b31465a3245e75be78","Air pollution resulting from rapid urbanization and associated human activities in the Kathmandu Valley of Nepal has been leading to serious public health concerns over the past 2 decades. These concerns led to a multinational field campaign SusKat-ABC (Sustainable atmosphere for the Kathmandu Valley - Atmospheric Brown Clouds) that measured different trace gases, aerosols and meteorological parameters in the Kathmandu Valley and surrounding regions during December 2012 to June 2013 to understand local- to regional-scale processes influencing air quality of the Kathmandu Valley. This study provides information about the regional distribution of ozone and some precursor gases using simultaneous in situ measurements from a SusKat-ABC supersite at Bode, Nepal, and two Indian sites: a high-altitude site, Nainital, located in the central Himalayan region and a low-altitude site, Pantnagar, located in the Indo-Gangetic Plain (IGP). The diurnal variations at Bode showed a daytime buildup in O3 while CO shows morning and evening peaks. Similar variations (with lower levels) were also observed at Pantnagar but not at Nainital. Several events of hourly ozone levels exceeding 80&thinsp;ppbv were also observed at Bode. The CO levels showed a decrease from their peak level of about 2000&thinsp;ppbv in January to about 680&thinsp;ppbv in June at Bode. The hourly mean ozone and CO levels showed a strong negative correlation during winter (<i>r</i>2 Combining double low line 0.82 in January and <i>r</i>2 Combining double low line 0.71 in February), but this negative correlation gradually becomes weaker, with the lowest value in May (<i>r</i>2 Combining double low line 0.12). The background O3 and CO mixing ratios at Bode were estimated to be about 14 and 325&thinsp;ppbv, respectively. The rate of change of ozone at Bode showed a more rapid increase ( ĝ1/4 17&thinsp;ppbv&thinsp;hĝ'1) during morning than the decrease in the evening (5-6&thinsp;ppbv&thinsp;hĝ'1), suggesting the prevalence of a semi-urban environ. The lower CO levels during spring suggest that regional transport also contributes appreciably to springtime ozone enhancement in the Kathmandu Valley on top of the local in situ ozone production. We show that regional pollution resulting from agricultural crop residue burning in northwestern IGP led to simultaneous increases in O3 and CO levels at Bode and Nainital during the first week of May 2013. A biomass-burning-induced increase in ozone and related gases was also confirmed by a global model and balloon-borne observations over Nainital. A comparison of surface ozone variations and composition of light non-methane hydrocarbons among different sites indicated the differences in emission sources of the Kathmandu Valley and the IGP. These results highlight that it is important to consider regional sources in air quality management of the Kathmandu Valley. © Author(s) 2018."
"35551238800;6602999057;56522444900;35736729500;7201572145;57200494488;7006837187;15827278200;57217801354;6603932982;7003510880;23995619200;6701679993;56032594900;7006424590;56187256200;8657166100;26422803600;9233178200;57195348014;27667585700;56183181400;57200504215;7005941217;55683878900;7006377579;7004393835;8412336900;6603180620;56495287900;57207256232;26659013400;8760535800;6603423022;57195673296;9536598800;25958833500;25228665000;55226243300;14058796400;55435417200;56195655500;55783064400;7004944088;16217869500;","The dynamics-aerosol-chemistry-cloud interactions in West Africa field campaign overview and research highlights",2018,"10.1175/BAMS-D-16-0256.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077624326&doi=10.1175%2fBAMS-D-16-0256.1&partnerID=40&md5=3d514f7b3bcf84930b53e2dc7c87e815",[No abstract available]
"55169203100;8871498000;24398842400;56250185400;","Parameterizing cloud condensation nuclei concentrations during HOPE",2016,"10.5194/acp-16-12059-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989216797&doi=10.5194%2facp-16-12059-2016&partnerID=40&md5=b04248b7d91bea0d4fe98624255d03df","An aerosol model was used to simulate the generation and transport of aerosols over Germany during the HD(CP)2 Observational Prototype Experiment (HOPE) field campaign of 2013. The aerosol number concentrations and size distributions were evaluated against observations, which shows satisfactory agreement in the magnitude and temporal variability of the main aerosol contributors to cloud condensation nuclei (CCN) concentrations. From the modelled aerosol number concentrations, number concentrations of CCN were calculated as a function of vertical velocity using a comprehensive aerosol activation scheme which takes into account the influence of aerosol chemical and physical properties on CCN formation. There is a large amount of spatial variability in aerosol concentrations; however the resulting CCN concentrations vary significantly less over the domain. Temporal variability is large in both aerosols and CCN. A parameterization of the CCN number concentrations is developed for use in models. The technique involves defining a number of best fit functions to capture the dependence of CCN on vertical velocity at different pressure levels. In this way, aerosol chemical and physical properties as well as thermodynamic conditions are taken into account in the new CCN parameterization. A comparison between the parameterization and the CCN estimates from the model data shows excellent agreement. This parameterization may be used in other regions and time periods with a similar aerosol load; furthermore, the technique demonstrated here may be employed in regions dominated by different aerosol species. © Author(s) 2016."
"7801634218;57210590791;7004715270;56893881700;37561696600;57190005849;57190007566;57189999417;","A multisensor investigation of rime splintering in tropical maritime cumuli",2016,"10.1175/JAS-D-15-0285.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976386649&doi=10.1175%2fJAS-D-15-0285.1&partnerID=40&md5=7865ad528f1abda669c33de04e6921ab","Three flights from the Ice in Clouds Experiment-Tropical (ICE-T) field campaign examined the onset of ice near the ascending cloud tops of tropical maritime cumuli as they cooled from 0° to -14°C. Careful quantitative analysis of ice number concentrations included manual scrutiny of particle images and corrections for possible particle-shattering artifacts. The novel use of the Wyoming Cloud Radar documented the stage of cloud development and tops relative to the aircraft sampling, complemented the manual estimates of graupel concentrations, and provided new clear evidence of graupel movement through the rime-splintering zone. Measurements of ice-nucleating particles (INPs) provided an estimate of primary initiated ice. The data portray a dynamically complex picture of hydrometeor transport contributing to, and likely resulting from, the rime-splintering process. Hundreds per liter of supercooled raindrops ascended within the updrafts as the cloud tops reached 0°C and contributed in part to the 0.1 L-1 graupel detected soon after the cloud tops cooled to -5°C. Rime splintering could thus be initiated upon first ascent of the cloud top through that zone and arguably contributed to the 1 L-1 or more graupel observed above it. Graupel ascending/descending into, or balanced within, the rime-splintering zone were found. In wider, less isolated clouds with dying updrafts and tops near -14°C, ice particle concentrations sometimes reached 100 L-1. Future 3D numerical modeling will be required to evaluate if rime splintering alone can explain the difference of three to four orders of magnitude in the observed INPs and the graupel observed at -5°C and colder. © 2016 American Meteorological Society."
"6701333444;6506545080;37018824600;55272477500;8859530100;36076994600;37116849700;9132948500;7402934750;56611366900;7409074131;7401936984;7203034123;55745955800;6701346974;","RACORO continental boundary layer cloud investigations: 1. case study development and ensemble large-scale forcings",2015,"10.1002/2014JD022713","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955749226&doi=10.1002%2f2014JD022713&partnerID=40&md5=391deaa6ab07bec4a01d78d84d8e4998","Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60 h case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in situ measurements from the Routine AAF (Atmospheric Radiation Measurement (ARM) Aerial Facility) CLOWD (Clouds with Low Optical Water Depth) Optical Radiative Observations (RACORO) field campaign and remote sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing data sets are derived from the ARM variational analysis, European Centre for Medium-Range Weather Forecasts, and a multiscale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in “trial” large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds. © 2015. American Geophysical Union. All Rights Reserved."
"25647334300;7103158465;6506385754;25031430500;7005729142;","Comparison of ice cloud properties simulated by the Community Atmosphere Model (CAM5) with in-situ observations",2014,"10.5194/acp-14-10103-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907432729&doi=10.5194%2facp-14-10103-2014&partnerID=40&md5=57fcbc199304f878de832769ec47b9f2","Detailed measurements of ice crystals in cirrus clouds were used to compare with results from the Community Atmospheric Model Version 5 (CAM5) global climate model. The observations are from two different field campaigns with contrasting conditions: Atmospheric Radiation Measurements Spring Cloud Intensive Operational Period in 2000 (ARM-IOP), which was characterized primarily by midlatitude frontal clouds and cirrus, and Tropical Composition, Cloud and Climate Coupling (TC4), which was dominated by anvil cirrus. Results show that the model typically overestimates the slope parameter of the exponential size distributions of cloud ice and snow, while the variation with temperature (height) is comparable. The model also overestimates the ice/snow number concentration (0th moment of the size distribution) and underestimates higher moments (2nd through 5th), but compares well with observations for the 1st moment. Overall the model shows better agreement with observations for TC4 than for ARM-IOP in regards to the moments. The mass-weighted terminal fall speed is lower in the model compared to observations for both ARM-IOP and TC4, which is partly due to the overestimation of the size distribution slope parameter. Sensitivity tests with modification of the threshold size for cloud ice to snow autoconversion (Dcs) do not show noticeable improvement in modeled moments, slope parameter and mass weighed fall speed compared to observations. Further, there is considerable sensitivity of the cloud radiative forcing to Dcs, consistent with previous studies, but no value of Dcs improves modeled cloud radiative forcing compared to measurements. Since the autoconversion of cloud ice to snow using the threshold size Dcs has little physical basis, future improvement to combine cloud ice and snow into a single category, eliminating the need for autoconversion, is suggested. © Author(s) 2014."
"47160951300;7004171611;55996365900;7201706659;","Mineral dust aerosol net direct radiative effect during GERBILS field campaign period derived from SEVIRI and GERB",2014,"10.1002/2013JD020681","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921350104&doi=10.1002%2f2013JD020681&partnerID=40&md5=e48496c4eb506c330601f2395bd815ac","Colocated Spinning Enhanced Visible and Infrared Imager (SEVIRI) retrieved dust optical depths at 0.55 microns, τ055, and Geostationary Earth Radiation Budget (GERB) fluxes at the top of atmosphere are used to provide, for the first time, an observationally based estimate of the cloud-free net direct radiative effect (DRE) of mineral dust aerosol from geostationary satellite observations, providing new insights into the influence of time of day on the magnitude and sign of the shortwave, longwave, and overall net effect during sunlit hours. Focusing on the Geostationary Earth Radiation Budget Intercomparison of Longwave and Shortwave radiation (GERBILS) campaign over North Africa during June 2007, the presence of mineral dust aerosol reduces the outgoing longwave radiation at all times of day with the peak reduction clearly following the diurnal cycle of surface temperature. The instantaneous shortwave DRE shows strong dependencies on pristine sky albedo and solar zenith angle such that the same dust loading can induce a positive or negative value dependent on time of day. However, the area mean net DRE over the GERBILS period is dominated by the longwave component at all sampled times of day, with mineral dust inducing a reduction in outgoing net flux of the order of 10 W m−2. Hence, in the mean sense, Saharan dust is found to warm the Earth-atmosphere system over northern Africa and the Middle East. © 2014. American Geophysical Union. All Rights Reserved."
"7201587909;7403577184;6701653010;6603431534;7202772927;","Two distinct modes in one-day rainfall event during MC3E field campaign: Analyses of disdrometer observations and WRF-SBM simulation",2012,"10.1029/2012GL053329","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84871558076&doi=10.1029%2f2012GL053329&partnerID=40&md5=466702d9bd78639ec3420057522c4784","A unique microphysical structure of rainfall is observed by the surface laser optical Particle Size and Velocity (Parsivel) disdrometers on 25 April 2011 during Midlatitude Continental Convective Clouds Experiment (MC3E). According to the systematic differences in rainfall rate and bulk effective droplet radius, the sampling data can be divided into two groups; the rainfall mostly from the deep convective clouds has relatively high rainfall rate and large bulk effective droplet radius, whereas the reverse is true for the rainfall from the shallow warm clouds. The Weather Research and Forecasting model coupled with spectral bin microphysics (WRF-SBM) successfully reproduces the two distinct modes in the observed rainfall microphysical structure. The results show that the up-to-date model can demonstrate how the cloud physics and the weather condition on the day are involved in forming the unique rainfall characteristic. © 2012. American Geophysical Union. All Rights Reserved."
"7202162685;6701324864;","Assessment of some parameterizations of heterogeneous ice nucleation in cloud and climate models",2012,"10.5194/acp-12-1151-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84867594480&doi=10.5194%2facp-12-1151-2012&partnerID=40&md5=bf23863ffe1efda90ec6ce4e5c87c6e6","Several different types of parameterization of heterogeneous ice nucleation for cloud and climate models have been developed over the past decades, ranging from empirically-derived expressions to parameterizations of ice crystal nucleation rates derived from theory, including the parameterization developed by the authors that includes simultaneous dependence on the temperature and saturation ratio, hereafter referred to as KC. Parameterizations schemes that address the deliquescence-heterogeneous-freezing (DHetF), which combines the modes of condensation freezing and immersion freezing, are assessed here in the context of thermodynamic constraints, laboratory measurements, and recent field measurements. It is shown that empirical schemes depending only on the ice saturation ratio or only on temperature can produce reasonable crystal concentrations, but ice crystal nucleation is thermodynamically prohibited in certain regions of the temperature-saturation ratio phase space. Some recent empirical parameterizations yield clouds that are almost entire liquid at temperatures as low as -35 C in contrast to cloud climatology. Reasonable performance of the KC ice nucleation scheme is demonstrated by comparison with numerous data from several recent field campaigns, laboratory data, climatology of cloud phase-state. Several mis-applications of the KC parameterization that appeared recently in the literature are described and corrected. It is emphasized here that a correct application of the KC scheme requires integration of the individual nucleation rates over the measured size spectrum of ice nuclei that represent a fraction or several fractions of the environmental aerosol with specific ice nucleation properties. The concentration in these fractions can be substantially smaller than that of the total aerosol, but greater than the crystal concentration measured by an experimental device. Simulations with temperature-dependent active site area or with several IN fractions having different properties show that ice nucleation in the KC scheme occurs in a wide temperature range of 10-20 C, which depends on IN properties. Simulation with a spectral bin model and correct application of KC scheme adequately describes ice nucleation via the DHetF mode and yields crystal concentrations and phase state close to those measured in the single-layer stratocumulus cloud observed in the Mixed Phase Arctic Cloud Experiment (MPACE). An assessment of some deficiencies in current parcel modeling methods and cloud chamber observations and their impact on parameterization development and evaluation is provided. © 2012 Author(s). CC Attribution 3.0 License."
"6602574676;6603453147;36098286300;7003397919;35468686100;","Taking the pulse of pyrocumulus clouds",2012,"10.1016/j.atmosenv.2012.01.045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858781257&doi=10.1016%2fj.atmosenv.2012.01.045&partnerID=40&md5=384bf37261d60cc19dff4f87085d0eee","Large forest fires are a known natural and dominant disturbance factor in high northern latitudes, and form pyrocumulus (pyroCu), and occasionally pyrocumulonimbus (pyroCb) clouds. These clouds can transport emissions into the upper troposphere/lower stratosphere (UT/LS) and produce significant regional and even global climate effects, as is the case with some volcanoes. However, the lack of observational data within pyroCu or pyroCb complicates our ability to investigate pyro-convection and to understand the vertical and cross-isentropic transport mechanisms responsible for UT/LS injection. Here, we report detailed airborne radiation measurements within strong pyroCu taken over boreal forest fires in Saskatchewan, Canada during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) summer field campaign in 2008. We find a prominent smoke core within the pyroCu, which is defined by strong extinction in the UV, VIS and NIR, and high gas-particle concentrations. We also find that the angular distribution of radiance within the pyroCu is closely related to the diffusion domain in water clouds, which is dominated by multiple scattering processes. The radiation field of pyroCu can be described by diffusion approximations that are comprised of simple cosine functions, which can be used to calculate the spatial and temporal characteristics of the radiance field, and applied in cloud resolving models. We demonstrate with Monte Carlo simulations that radiation transport in pyroCu is inherently a 3D problem and must account for particle absorption. © 2012 Elsevier Ltd."
"35867442600;7003708056;7003880283;26634569400;6602177985;6603297364;7101600670;","The influence of aerosol particle number and hygroscopicity on the evolution of convective cloud systems and their precipitation: A numerical study based on the COPS observations on 12 August 2007",2010,"10.1016/j.atmosres.2010.05.003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79951888992&doi=10.1016%2fj.atmosres.2010.05.003&partnerID=40&md5=0f00598fb029701d1f91506b0b228665","The 3D cloud model DESCAM-3D with bin resolved microphysics for ice, water and aerosol particles is used to study the role of particles on the evolution of summertime mid-level convective clouds and the subsequent precipitation during the COPS field campaign which occurred at mid-latitude near the French/German border in summer 2007. Using a 3D grid resolution of 250 m, DESCAM-3D, is able to simulate well the dynamical, cloud and precipitation features of the convective cloud system observed during the afternoon of the 12th August. This mid-level convective system was dominated by warm-phase microphysics. The simulated convective system led to a 1.5 h long lasting precipitation event in agreement with the radar observations. The results of the fine numerical scale compare well with the high resolved radar reflectivities of the LaMP X-band radar and the DLR-Poldirad radar. The prediction of the liquid hydrometeor spectra allows a detailed calculation of the cloud radar reflectivity. In order to better understand the role of aerosol particles on cloud evolution and precipitation formation, several sensitivity studies were performed by modifying aerosol number concentration as well as their physico-chemical properties. Drastic changes in the aerosol solubility lead to a variation in precipitation on the order of 10% for the same convective case. In contrast, changes in the aerosol number concentrations can lead to a variation in total precipitation of up to 30%. Hence, the role of changes in aerosol number concentrations is more important than changes in particle solubility for this case of continental mid-level convection at mid-latitude. A subsequent analysis of the in-cloud microphysics revealed that in-cloud properties are modified significantly in all scenarios. Key parameter is the supersaturation whose magnitude influences both cloud microphysics (cloud droplet and rain drop formation) as well as cloud thermodynamics and cloud dynamics. Furthermore, supersaturation can remain quite low in polluted clouds reducing strongly the release of latent heat and, thus, the intensity of the convective dynamics. As much as a quarter of the polluted cloud volume was found to be subsaturated in this case whereas it was smaller in the continental or clean environments. © 2010 Elsevier B.V."
"6602574676;7003478309;35468686100;6603019259;","Simultaneous retrieval of aerosol and surface optical properties from combined airborne- and ground-based direct and diffuse radiometric measurements",2010,"10.5194/acp-10-2777-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860388961&doi=10.5194%2facp-10-2777-2010&partnerID=40&md5=623dcf2282da891739f0f9644a7eb7dc","This paper presents a new method for simultaneously retrieving aerosol and surface reflectance properties from combined airborne and ground-based direct and diffuse radiometric measurements. The method is based on the standard Aerosol Robotic Network (AERONET) method for retrieving aerosol size distribution, complex index of refraction, and single scattering albedo, but modified to retrieve aerosol properties in two layers, below and above the aircraft, and parameters on surface optical properties from combined datasets (Cloud Absorption Radiometer (CAR) and AERONET data). A key advantage of this method is the inversion of all available spectral and angular data at the same time, while accounting for the influence of noise in the inversion procedure using statistical optimization. The wide spectral (0.34-2.30 μm) and angular range (180°) of the CAR instrument, combined with observations from an AERONET sunphotometer, provide sufficient measurement constraints for characterizing aerosol and surface properties with minimal assumptions. The robustness of the method was tested on observations made during four different field campaigns: (a) the Southern African Regional Science Initiative 2000 over Mongu, Zambia, (b) the Intercontinental Transport Experiment-Phase B over Mexico City, Mexico (c) Cloud and Land Surface Interaction Campaign over the Atmospheric Radiation Measurement (ARM) Central Facility, Oklahoma, USA, and (d) the Arctic Research of the Compo-sition of the Troposphere from Aircraft and Satellites (ARCTAS) over Elson Lagoon in Barrow, Alaska, USA. The four areas are dominated by different surface characteristics and aerosol types, and therefore provide good test cases for the new inversion method. © Author(s) 2010. This work is distributed under."
"6701670597;6701431208;6701346974;36876405100;57218978147;","Virtual field campaigns on deep tropical convection in climate models",2009,"10.1175/2008JCLI2203.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-64049093073&doi=10.1175%2f2008JCLI2203.1&partnerID=40&md5=a9d3cc3afada5394734f7481522a78c7","High-resolution time-height data over warm tropical oceans are examined, from three global atmosphere models [GFDL's Atmosphere Model 2 (AM2), NCAR's Community Atmosphere Model, version 3 (CAM3), and a NASA Global Modeling and Assimilation Office (GMAO) model], field campaign observations, and observation-driven cloud model outputs. The character of rain events is shown in data samples and summarized in lagged regressions versus surface rain rate. The CAM3 humidity and cloud exhibit little vertical coherence among three distinct layers, and its rain events have a short characteristic time, reflecting the convection scheme's penetrative nature and its closure's concentrated sensitivity to a thin boundary layer source level. In contrast, AM2 rain variations have much longer time scales as convection scheme plumes whose entrainment gives them tops below 500 hPa interact with humidity variations in that layer. Plumes detraining at model levels above 500 hPa are restricted by cloud work function thresholds, and upper-tropospheric humidity and cloud layers fed by these are detached from the lower levels and are somewhat sporadic.With these discrete entrainment rates and instability thresholds, AM2 also produces some synthetic-looking noise (sharp features in height and time) on top of its slow rain variations. A distinctive feature of the NASA model is a separate anvil scheme, distinct from the main large-scale cloud scheme, fed by relaxed Arakawa-Schubert (RAS) plume ensemble convection (a different implementation than in AM2). Its variability is rich and vertically coherent, and involves a very strong vertical dipole component to its tropospheric heating variations, of both signs (limited-depth convective heating and top-heavy heating in strong deep events with significant nonconvective rain). Grid-scale saturation events occur in all three models, often without nonconvective surface rain, causing relatively rare episodes of large negative top-of-atmosphere cloud forcing. Overall, cloud forcing regressions show a mild net positive forcing by rain-correlated clouds in CAM3 and mild net cooling in the other models, as the residual of large canceling shortwave and longwave contributions. © 2009 American Meteorological Society."
"15840204100;55946567900;9633685900;7004114883;55386235300;35422648700;7004102113;","Wakasa Bay: An AMSR precipitation validation campaign",2007,"10.1175/BAMS-88-4-551","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249084292&doi=10.1175%2fBAMS-88-4-551&partnerID=40&md5=ca98f553f1a726f78bc3c75c1db2508d","The ""Wakasa Bay Experiment"" was conducted in order to refine error models for oceanic precipitation from the Advanced Microwave Sounding Radiometer-Earth Observing System (AMSR-E) measurements and to develop algorithms for snowfall. The NASA P-3 aircraft was equipped with microwave radiometers, covering a frequency range of 10.7-340 GHz, and radars at 13.4, 35.6, and 94 GHz, and was deployed to Yokota Air Base in Japan for flights from 14 January to 3 February 2003. For four flight days (27-30 January) a Gulfstream II aircraft provided by Core Research for Environmental Science and Technology (CREST), carrying an extensive cloud physics payload and a two-frequency (23.8 and 31.4 GHz) microwave radiometer, joined the P-3 for coordinated flights. The Gulfstream II aircraft was part of the ""Winter Mesoscale Convective Systems Observations over the Sea of Japan in 2003"" (""WMO-03"") field campaign sponsored by Japan Science and Technology Corporation (JST). Extensive data were taken, which addressed all of the experimental objectives. The data obtained with the NASA P-3 are available at the National Snow and Ice Data Center (NSIDC), and they are available free of charge to all interested researchers. ©2007 American Meteorological Society."
"13006903300;56218731300;6602715030;13005116700;","Evaluation of the ALADIN 3D-VAR with observations of the MAP campaign",2006,"10.1007/s00703-005-0156-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33645960101&doi=10.1007%2fs00703-005-0156-5&partnerID=40&md5=4f46756f31890e91f8fd900cfa5ace55","The aim of this work is to evaluate several 3D-VAR assimilation cycles in the limited area model ALADIN, in comparison with the dynamical adaptation of the global model (ARPEGE) analysis, and with a focus on the precipitation forecasts. We perform a detailed evaluation for a specific, well documented, test case: Intensive observing period 14 of the Mesoscale Alpine Programme (MAP) field campaign, which is well described through various MAP data. The meteorological situation was of high interest, with triggering of convection both over the Alps and over the sea, therefore it has been chosen as the framework of our case study. There are clear benefits in favour of the 3D-VAR assimilation cycles over the first hours of forecast thanks to the observations and to the preservation of small-scale features. These improvements are further enhanced with a large-scale update step added to the 3D-VAR analysis. Innovative data are used, such as relative humidity pseudo-profiles which are processed data generated from cloud classification. They bring an important information which can redesign the frontal areas. When they are used jointly with the conventional observations in the 3D-VAR, they also lead to an improvement of the precipitation scores. © Springer-Verlag 2006."
"24322892500;6701859365;7201463831;7201798916;7004174939;16185051500;6602137800;35554446700;","EOS terra aerosol and radiative flux validation: An overview of the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) experiment",2005,"10.1175/JAS3398.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-18544390219&doi=10.1175%2fJAS3398.1&partnerID=40&md5=ff114149512dae6496fc04818978bfaf","NASA developed an Earth Observing System (EOS) to study global change and reduce uncertainties associated with aerosols and other key parameters controlling climate. The first EOS satellite, Terra, was launched in December 1999. The Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaign was conducted from 10 July to 2 August 2001 to validate several Terra data products, including aerosol properties and radiative flux profiles derived from three complementary Terra instruments: the Clouds and the Earth's Radiant Energy System (CERES), the Multiangle Imaging Spectroradiometer (MISR), and the Moderate Resolution Imaging Spectroradiometer (MODIS). CERES, MISR, and MODIS are being used to investigate the critical role aerosols play in modulating the radiative heat budget of the earth-atmosphere system. CLAMS' primary objectives are to improve understanding of atmospheric aerosols, to validate and improve the satellite data products, and to test new instruments and measurement concepts. A variety of in situ sampling devices and passive remote sensing instruments were flown on six aircraft to characterize the state of the atmosphere, the composition of atmospheric aerosols, and the associated surface and atmospheric radiation parameters over the U.S. eastern seaboard. Aerosol particulate matter was measured at two ground stations established at Wallops Island, Virginia, and the Chesapeake Lighthouse, the site of an ongoing CERES Ocean Validation Experiment (COVE) where well-calibrated radiative fluxes and Aerosol Robotic Network (AERONET) aerosol properties have been measured since 1999. Nine coordinated aircraft missions and numerous additional sorties were flown under a variety of atmospheric conditions and aerosol loadings. On one ""golden day"" (17 July 2001), under moderately polluted conditions with midvisible optical depths near 0.5, all six aircraft flew coordinated patterns vertically stacked between 100 and 65 000 ft over the COVE site as Terra flew overhead. This overview presents a description of CLAMS objectives, measurements, and sampling strategies. Key results, reported in greater detail in the collection of papers found in this special issue, are also summarized. © 2005 American Meteorological Society."
"7402925142;7005864717;55259200300;7203064998;","Properties of the size-resolved and individual cloud droplets collected in western Japan during the Asian dust storm event",2004,"10.1016/j.atmosenv.2004.05.032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3242704215&doi=10.1016%2fj.atmosenv.2004.05.032&partnerID=40&md5=e763f96bbc8180d88eb625ab765ac2ca","With the point of view of the removal mechanism of Asian dust storm particles, in order to study the physiochemical properties of clouds a field campaign was conducted in western Japan during the Asian dust storm event. The polymeric water absorbent film and collodion film replication techniques were employed in the measurements of size-fractionated precipitation cloud and individual cloud droplets, respectively. In addition, to investigate the source profiles of the elements retained in cloud samples, the original desert sand was collected. Particle-induced X-ray emission was applied for the elemental analysis of size-resolved cloud droplets and desert sand. Also for the quantification analysis of the ultra trace elements in residual particles in individual cloud droplets, the X-ray microprobe system equipped at Super Photon ring-8GeV (SPring-8) BL-37XU was newly applied. Soil derived components like Si, Ca, and Fe show higher mass concentrations in small droplets (&lt;6.4μm) than in large droplets (&gt;6.4μm), while S and Cl dominate at droplet size larger than 20μm. Three cloud samples have liquid water content ranging from 0.04 to 0.11gm-3. The number size distribution of droplets collected at cloud base is monomodal with the maximum level around 15μm. The size distribution of cloud droplets is widespread (up to 60μm). The droplet residues mainly consisting of crustal components were successively reconstructed as elemental maps by the X-ray fluorescence (XRF) microprobe analytical technique. From these XRF elemental maps, it can be understood that crustal components are significantly distributed on and/or in the residual particles in individual cloud droplets. The plotting of enrichment factors calculated from the elemental composition of original desert sand in China not only indicates the good correlationship between elemental masses in residual particles of cloud base droplets and those of precipitation cloud, but also classify elements into soil origin and non-soil origin. Mineral components were identified as the main components of dry residual particles in cloud droplets. These soil-origin elements account for up to 68% of the total elemental mass. © 2004 Elsevier Ltd. All rights reserved."
"7409080503;8839875600;6603742681;","Impact of surface inhomogeneity on solar radiative transfer under overcast conditions",2002,"10.1029/2001JD000976","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0442318756&doi=10.1029%2f2001JD000976&partnerID=40&md5=766ebb9fa87810c0db29438ea62b4f13","The goal of this study was to assess the ability of the Moderate-Resolution Transmittance 4 (MODTRAN-4) code to simulate high-resolution shortwave (SW) fluxes given detailed and complete input information under overcast conditions. The study underlines the impact of surface inhomogeneity on the closure of SW radiative transfer. It also leads to a method of estimating surface spectral areal-mean albedo from downwelling solar transmittance measurements. The investigation made use of ample Atmospheric Radiation Measurement (ARM) field data collected by a suite of instruments, including broadband and narrowband radiometers and spectrometers, cloud radar and lidar, microwave radiometer, atmospheric sounding instruments, and satellite data. Furnishing the MODTRAN-4 code with observed atmospheric, cloud, and surface parameters generates spectral solar transmittance at the surface and reflectance at the top of the atmosphere (TOA). The transmittances were compared with the Rotating Shadowband Spectroradiometer measurements and showed significant discrepancies in the near-infrared (NIR) region, the bulk of which was attributed to the use of unrepresentative surface spectral albedos. A field campaign was undertaken to collect surface albedo data for a wide variety of land cover types near the ARM Central Facility. The sampled data were combined with thematic mapper/Landsat-based land cover classification data to map surface spectral albedo. Substitution of the derived areal-mean spectral albedo into the MODTRAN-4 model eliminates major discrepancies in the NIR, and also leads to good agreements with surface solar broadband fluxes and TOA satellite spectral reflectance. On the basis of these findings, one may use downwelling spectral transmittance data, together with detailed cloud and atmospheric information, to estimate surface effective areal-mean albedo. The estimated values agree well with those derived from the ground survey data. Following the method, a data set of effective areal-mean spectral albedo throughout a year was. obtained. Copyright 2002 by the American Geophysical Union."
"57217744031;7004910963;7003485805;6603403986;55409586800;","Radiation exchanges above West African moist savannas: seasonal patterns and comparison with a GCM simulation",1994,"10.1029/94jd01526","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028595437&doi=10.1029%2f94jd01526&partnerID=40&md5=e26cba6e4c0d60ef16e712f1b1925644","Problems which appear when point observations of surface fluxes are compared with results from general circulation model simulations are addressed. Seasonal variations of the prescribed savanna albedo in the model differed significantly from the observed variations due to bush fire influence. However, the major discrepancy between model simulations and surface observations resulted from the overestimation of the incoming shortwave radiation at the surface. The major sources of discrepancy were found to be the simulated clear-sky atmospheric absorption and/or scattering of the shortwave radiation and the simulation of cloud and/or cloud-radiation interactions which lead to an overestimation of the absorbed energy at the surface by the model. -from Authors"
"35509639400;7201504886;","Measuring area-averaged vertical motions with dropsondes",2019,"10.1175/JAS-D-18-0141.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063578716&doi=10.1175%2fJAS-D-18-0141.1&partnerID=40&md5=56a20a6fa252fd5823f3808cd250a8a7","Measurements of vertical profiles of areal-mean mass divergence, vorticity, and vertical velocity, based on dropsondes distributed over an area of 25 000 km2, are presented. The dropsondes were released with high frequency along circular flight patterns during an airborne field campaign taking place over the tropical Atlantic near Barbados. Vertical profiles of the area-averaged mass divergence and vorticity were computed from the horizontal wind profiles, and the area-averaged vertical velocity was then inferred from the divergence. The consistency of measurements over pairs of circles flown within the same air mass demonstrated the reproducibility of the measurements, and showed that they characterize the environmental conditions on the scale of the measurement, rather than being dominated by measurement error or small-scale wind variability. The estimates from dropsondes were found to be consistent with the observed cloud field, with Lagrangian estimates of the mean vertical velocity inferred from the free-tropospheric humidity field, and with the mean vertical velocity derived from simulations using an atmospheric model representing kilometerscale motions and initialized with meteorological analyses. In trade wind-like conditions, the divergence and vorticity profiles exhibit a rich vertical structure and a significant variability in space and time. Yet a few features appear to be robust, such as the presence of layers of mass convergence at the top of moist layers, extrema of the area-averaged vertical velocity at the top of the subcloud layer and in the midtroposphere, and minima around the trade inversion near 2 km. The analysis of spatial and temporal autocorrelation scales suggests that the divergent mass field measured from dropsondes is representative of the environment of shallow clouds. © 2019 American Meteorological Society."
"7003334425;6603186492;35551238800;57218412810;7003899504;23019619200;8615886200;6603343882;6701422868;7004393835;6602176524;55683576200;56212055700;56495287900;6602336571;6603934961;55949293000;57205419456;15319055900;35299194600;57200135454;57205842560;55802221900;57204983024;55915387400;57204921091;57209689805;57200368817;35463545000;57208460143;","The aerosols, radiation and clouds in southern Africa field campaign in Namibia overview, illustrative observations, and way forward",2019,"10.1175/BAMS-D-17-0278.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070887988&doi=10.1175%2fBAMS-D-17-0278.1&partnerID=40&md5=47a916ef5de11163109d4b888e81c0d0","New ground-based and aircraft measurements in Namibia will improve the understanding of the role of aerosols on the regional climate of the southeast Atlantic Ocean offshore southern Africa. © 2019 American Meteorological Society."
"57188729343;36106191000;6506848120;55801231800;7004557737;7103197731;57195257572;7103204204;57190209035;57204252724;8550791300;7402838215;","Classification of Arctic, midlatitude and tropical clouds in the mixed-phase temperature regime",2017,"10.5194/acp-17-12219-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026373560&doi=10.5194%2facp-17-12219-2017&partnerID=40&md5=faa0b9f13bfbd8a54bcf42263a79d828","The degree of glaciation of mixed-phase clouds constitutes one of the largest uncertainties in climate prediction. In order to better understand cloud glaciation, cloud spectrometer observations are presented in this paper, which were made in the mixed-phase temperature regime between 0 and -38°C (273 to 235K), where cloud particles can either be frozen or liquid. The extensive data set covers four airborne field campaigns providing a total of 139000 1Hz data points (38.6h within clouds) over Arctic, midlatitude and tropical regions. We develop algorithms, combining the information on number concentration, size and asphericity of the observed cloud particles to classify four cloud types: liquid clouds, clouds in which liquid droplets and ice crystals coexist, fully glaciated clouds after the Wegener-Bergeron-Findeisen process and clouds where secondary ice formation occurred. We quantify the occurrence of these cloud groups depending on the geographical region and temperature and find that liquid clouds dominate our measurements during the Arctic spring, while clouds dominated by the Wegener-Bergeron-Findeisen process are most common in midlatitude spring. The coexistence of liquid water and ice crystals is found over the whole mixed-phase temperature range in tropical convective towers in the dry season. Secondary ice is found at midlatitudes at -5 to -10°C (268 to 263K) and at higher altitudes, i.e. lower temperatures in the tropics. The distribution of the cloud types with decreasing temperature is shown to be consistent with the theory of evolution of mixed-phase clouds. With this study, we aim to contribute to a large statistical database on cloud types in the mixed-phase temperature regime. © 2017 Author(s)."
"57191430389;55481275400;56210720700;7003361863;7403247998;7101846027;35340122000;7006572336;57196499374;16308514000;","Relationships between giant sea salt particles and clouds inferred from aircraft physicochemical data",2017,"10.1002/2016JD026019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017138428&doi=10.1002%2f2016JD026019&partnerID=40&md5=46ecb6ba7f71ff202d6de560ace14bf0","This study uses airborne data from multiple field campaigns off the California coast to determine the extent to which a size distribution parameter and a cloud water chemical measurement can capture the effect of giant cloud condensation nuclei (GCCN), specifically sea salt, on marine stratocumulus cloud properties. The two GCCN proxy variables, near-surface particle number concentration for diameters >5 µm and cloud water chloride concentration, are significantly correlated (95% confidence) with each other, and both exhibit expected relationships with other parameters (e.g., surface wind) that typically coincide with sea salt emissions. Factors influencing the relationship between these two GCCN proxy measurements include precipitation rate (R) and the standard deviation of the subcloud vertical velocity owing likely to scavenging effects and improved mixing/transport of sea salt to cloud base, respectively. When comparing 12 pairs of high and low chloride cloud cases (at fixed liquid water path and cloud drop number concentration), the average drop spectra for high chloride cases exhibit enhanced drop number at diameters exceeding 20 µm, especially above 30 µm. In addition, high chloride cases coincide with enhanced mean columnar R and negative values of precipitation susceptibility. The difference in drop effective radius between high and low chloride conditions decreases with height in cloud, suggesting that some GCCN-produced raindrops precipitate before reaching cloud tops. The sign of cloud responses (i.e., R) to perturbations in giant sea salt particle concentration, as evaluated from Modern Era Retrospective Analysis for Research and Applications version 2 reanalysis data, is consistent with the aircraft data. © 2017. American Geophysical Union. All Rights Reserved."
"7004369046;7407016988;24485218400;9132948500;7401936984;","Relationships between radiation, clouds, and convection during DYNAMO",2017,"10.1002/2016JD025965","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014003964&doi=10.1002%2f2016JD025965&partnerID=40&md5=c3c8bf05caa91b7a3a21d2b1427a2ee0","The relationships between radiation, clouds, and convection on an intraseasonal time scale are examined with data taken during the Dynamics of the Madden-Julian Oscillation (MJO) field campaign. Specifically, column-net, as well as vertical profiles of radiative heating rates, computed over Gan Island in the central Indian Ocean (IO) are used along with an objective analysis of large-scale fields to examine three MJO events that occurred during the 3 month period (October to December 2011) over this region. Longwave (LW) and shortwave radiative heating rates exhibit tilted structures, reflecting radiative effects associated with the prevalence of shallow cumulus during the dry, suppressed MJO phase followed by increasing deep convection leading into the active phase. As the convection builds going into the MJO active phase, there are increasingly top-heavy anomalous radiative heating rates while the column-net radiative cooling rate &lt;Qr&gt; progressively decreases. Temporal fluctuations in the cloud radiative forcing, being quite sensitive to changes in high cloudiness, are dominated by LW effects with an intraseasonal variation of ~0.4-0.6 K/d. While both the water vapor and cloud fields are inextricably linked, it appears that the tilted radiative structures are more related to water vapor effects. The intraseasonal variation of column-net radiative heating &lt;Qr&gt; enhances the convective signal in the mean by ~20% with a minimum in this enhancement ~10 days prior to peak MJO rainfall and maximum ~7 days after. This suggests that as MJO convective envelope weakens over the central IO, cloud-radiative feedbacks help maintain the mature MJO as it moves eastward. © 2017. American Geophysical Union. All Rights Reserved."
"21740519000;6508155070;35742842700;56387672900;6603423022;56032594900;7004854393;36338176900;","Boundary-layer turbulent processes and mesoscale variability represented by numerical weather prediction models during the BLLAST campaign",2016,"10.5194/acp-16-8983-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979544408&doi=10.5194%2facp-16-8983-2016&partnerID=40&md5=11258c5182bf107b94d57b5fbb340d17","This study evaluates the ability of three operational models, with resolution varying from 2.5 to 16 km, to predict the boundary-layer turbulent processes and mesoscale variability observed during the Boundary Layer Late-Afternoon and Sunset Turbulence (BLLAST) field campaign. We analyse the representation of the vertical profiles of temperature and humidity and the time evolution of nearsurface atmospheric variables and the radiative and turbulent fluxes over a total of 12 intensive observing periods (IOPs), each lasting 24 h. Special attention is paid to the evolution of the turbulent kinetic energy (TKE), which was sampled by a combination of independent instruments. For the first time, this variable, a central one in the turbulence scheme used in AROME and ARPEGE, is evaluated with observations. In general, the 24 h forecasts succeed in reproducing the variability from one day to another in terms of cloud cover, temperature and boundary-layer depth. However, they exhibit some systematic biases, in particular a cold bias within the daytime boundary layer for all models. An overestimation of the sensible heat flux is noted for two points in ARPEGE and is found to be partly related to an inaccurate simplification of surface characteristics. AROME shows a moist bias within the daytime boundary layer, which is consistent with overestimated latent heat fluxes. ECMWF presents a dry bias at 2 m above the surface and also overestimates the sensible heat flux. The high-resolution model AROME resolves the vertical structures better, in particular the strong daytime inversion and the thin evening stable boundary layer. This model is also able to capture some specific observed features, such as the orographically driven subsidence and a welldefined maximum that arises during the evening of the water vapour mixing ratio in the upper part of the residual layer due to fine-scale advection. The model reproduces the order of magnitude of spatial variability observed at mesoscale (a few tens of kilometres). AROME provides a good simulation of the diurnal variability of the turbulent kinetic energy, while ARPEGE shows the right order of magnitude. © Author(s) 2016. CC Attribution 3.0 License."
"56276083600;57062373800;57063308000;56962771900;36796969000;6603292201;","Morning transition case between the land and the sea breeze regimes",2016,"10.1016/j.atmosres.2015.12.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954558064&doi=10.1016%2fj.atmosres.2015.12.019&partnerID=40&md5=6792a17bec6b496ec0c7d029dce0e0ba","An experimental field campaign took place in September 2013 near the coastline in the southeastern Campos basin in the island of Mallorca to characterize experimentally the transition between the sea and the land breezes and to further study the successful cases with the corresponding high-resolution numerical simulations. Favorable weather conditions were only found for one episode that comprised a well-formed nocturnal land breeze, followed by the morning transition to sea breeze until noon the next day, when incoming clouds switched off the breeze regime. To analyse this transition between land and sea breezes, the official network of stations is used, supplemented by a portable station close to the shore and soundings of temperature (taken by a captive balloon and remotely controlled multicopter). These data are used to check the goodness of the corresponding simulation at a horizontal resolution of 1 km. Model and observations see similarly both regimes and the transition, showing some differences in the timing and the details in the surface layer. This transient event is analyzed in terms of phases, going consecutively through land breeze, phase previous to the sea breeze, when land heating starts, but it is still colder than the sea, the preparatory phase when the land becomes warmer than the sea, and the development phase when the breeze front progresses inland. © 2016 Elsevier B.V."
"55795656900;7405489798;7003495982;","Roles of deep and shallow convection and microphysics in the MJO simulated by the model for prediction across scales",2016,"10.1002/2015JD024697","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988850620&doi=10.1002%2f2015JD024697&partnerID=40&md5=2decf9385712dae54933d217d61176d0","The November event of the Madden-Julian oscillation (MJO) during the Dynamics of North Atlantic Models (DYNAMO) field campaign was simulated using the global compressible nonhydrostatic Model for Prediction Across Scales with global coarse (60 and 15 km) and regional (the Indian Ocean) cloud-permitting (3 km) meshes. The purpose of this study is to compare roles of parameterized deep and shallow cumulus and microphysics in MJO simulations. Two cumulus schemes were used: Tiedtke and Grell-Freitas. The deep and shallow components of Tiedtke scheme can be turned on and off individually. The results reveal that microphysics alone (without cumulus parameterization) is able to produce strong signals of the MJO in precipitation with 3 km mesh and weak MJO signals with 15 km mesh. A shallow scheme (Tiedtke) along with microphysics strengthens the MJO signals but makes them less well organized on large scales. A deep cumulus scheme can either improve the large-scale organization of MJO precipitation produced by microphysics and shallow convection (Tiedtke) or impair them (Grell-Freitas). The deep scheme of Tiedtke cannot reproduce the MJO well without its shallow counterpart. The main role of shallow convection in the model is to transport moisture upward to the lower to middle troposphere. By doing so, it removes dry biases in the lower to middle troposphere, a distinct feature in simulations with weak or no MJO signals, and enhances total precipitation and diabatic heating produced by microphysics and deep cumulus schemes. Changing model grid spacing from 60 to 15 km makes a little difference in the model fidelity of reproducing the MJO. All roles of shallow convection in 15 km simulations with parameterized deep convection cannot be reproduced in 3 km simulations without parameterized deep convection. Results from this study suggest that we should pay more attention to the treatment of shallow convection and its connection to other parameterized processes for improving MJO simulations. In other words, a holistic approach should be taken that consider parameterization of shallow cumulus, microphysics, boundary layer, and deep cumulus as a whole for model improvement. © 2016. American Geophysical Union. All Rights Reserved."
"56421721900;7005071296;55575074000;22036874400;","Overview of the D3R observations during the IFloodS field experiment with emphasis on rainfall mapping and microphysics",2015,"10.1175/JHM-D-15-0023.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947610063&doi=10.1175%2fJHM-D-15-0023.1&partnerID=40&md5=f35ca16860990a0bd96bde5555edf9e0","The NASA dual-frequency, dual-polarization Doppler radar (D3R) was deployed as part of the GPM Iowa Flood Studies (IFloodS) ground validation field campaign from 1 May through 15 June 2013. The D3R participated in a multi-instrument targeted investigation of convective initiation and hydrological response in the midwestern United States. An overview of the D3R's calibration and observations is presented.Amethod for attenuation correction of Ka-band observations using Ku-band results is introduced. Dual-frequency ratio estimates in stratiform rain and ice are presented and compared with theoretical values. Ku-band quantitative precipitation estimation results are validated against IFloodS ground instruments. © 2015 American Meteorological Society."
"56525018700;35423038600;55484222300;","Idealised simulations of polar low development in an Arctic moist-baroclinic environment",2015,"10.1002/qj.2507","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84941180264&doi=10.1002%2fqj.2507&partnerID=40&md5=a262218067de4a8bb00fd3349e07f669","This study examines the influence of moisture, baroclinicity, and static stability on developing disturbances at high latitudes by utilising an idealised baroclinic channel model. The set-up is composed of environmental baroclinicity defined by a zonally uniform jet in thermal wind balance with a meridional temperature gradient and moisture content defined by relative humidity profiles. Initiation of disturbance growth is achieved by superimposing a weak, surface-based warm-cored cyclonic disturbance to the set-up. The experiments show that the disturbance is able to amplify within such an environment in the absence of an upper-level perturbation, surface fluxes, friction, or radiation. Separation between developing and non-developing disturbances is feasible by considering the baroclinic and diabatic contributions to eddy available potential energy. Developing disturbances show a clear diabatic dominance during the early stage of development, whereas experiments lacking this diabatic boost fail to intensify within a 3-day time window. A comparison with the conceptual framework of the Diabatic Rossby Vortex (DRV) growth mechanism provides insight into the dynamical pathway potentially underlying the enhanced amplification. The emerging disturbance qualitatively resembles the postulated DRV structure, the major difference being a decreased depth in comparison with simulated and observed DRVs in midlatitudes. A suit of sensitivity experiments examines the range of atmospheric conditions in which enhanced amplification by diabatic processes is possible. Threshold values for moisture content and isentropic slopes are identified. This in-flight photo, taken on 26 March 2013 during the ACCACIA field campaign, captures a striking contrast between the calm ocean in the foreground and a vigorous polar low in the distance. Cloud formation and the associated latent heat release are often hypothesized to provide a substantial energy source for polar low development. In this study we utilize an idealized modelling framework to explore the potential impact of latent heat release on polar low development in baroclinic environments. The results illustrate that latent heating can provide a significant amplification of low-level disturbances at high latitudes. © 2015 Royal Meteorological Society."
"56924432700;16402575500;7004643405;6506458269;7005891596;6603775815;56214091200;57208931505;57197517376;8359591200;","Evidence of mixing between polluted convective outflow and stratospheric air in the upper troposphere during DC3",2014,"10.1002/2014JD022109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84939256971&doi=10.1002%2f2014JD022109&partnerID=40&md5=5216da5b01560c426b4d143a90e823e4","Aircraft measurements, including non-methane hydrocarbons (NMHCs), long-lived halocarbons, carbon monoxide (CO), and ozone (O3) collected on board the NASA DC-8 during the Deep Convection, Clouds, and Chemistry (DC3) field campaign (May – June 2012), were used to investigate interactions and mixing between stratospheric intrusions and polluted air masses. Stratospherically influenced air masses were detected using a suite of long-lived halocarbons, including chlorofluorocarbons (CFCs) and HCFCs, as a tracer for stratospheric air. A large number of stratospherically influenced samples were found to have reduced levels of O3 and elevated levels of CO (both relative to background stratospheric air), indicative of mixing with anthropogenically influenced air. Using n-butane and propane as further tracers of anthropogenically influenced air, we show that this type of mixing was present both at low altitudes and in the upper troposphere (UT). At low altitudes, this mixing resulted in O3 enhancements consistent with those reported at surface sites during deep stratospheric intrusions, while in the UT, two case studies were performed to identify the process by which this mixing occurs. In the first case study, stratospheric air was found to be mixed with aged outflow from a convective storm, while in the second case study, stratospheric air was found to have mixed with outflow from an active storm occurring in the vicinity of a stratospheric intrusion. From these analyses, we conclude that deep convective events may facilitate the mixing between stratospheric air and polluted boundary layer air in the UT. Throughout the entire DC3 study region, this mixing was found to be prevalent: 72% of all samples that involve stratosphere-troposphere mixing show influence of polluted air. Applying a simple chemical kinetics analysis to these data, we show that during DC3, the instantaneous production of hydroxyl radical (OH) in these mixed stratospheric-polluted air masses was 11 ± 8 times higher than that of stratospheric air, and 4.2 ± 1.8 times higher than that of background upper tropospheric air. © 2014. American Geophysical Union. All Rights Reserved."
"6602336571;6603484248;16246865300;55622632000;6701902921;","Chemical fate and settling of mineral dust in surface seawater after atmospheric deposition observed from dust seeding experiments in large mesocosms",2014,"10.5194/bg-11-5581-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897626312&doi=10.5194%2fbg-11-5581-2014&partnerID=40&md5=9b38b45423613c1902669f1490a4993c","We report here the elemental composition of sinking particles in sediment traps and in the water column following four artificial dust seeding experiments (each representing a flux of 10 gm-2). Dry or wet dust deposition were simulated during two large mesocosms field campaigns that took place in the coastal water of Corsica (NW Mediterranean Sea) representative of oligotrophic conditions. The dust additions were carried out with fresh or artificially aged dust (i.e., enriched in nitrate and sulfate by mimicking cloud processing) for various biogeochemical conditions, enabling us to test the effect of these parameters on the chemical composition and settling of dust after deposition. The rates and mechanisms of total mass, particulate organic carbon (POC) and chemical elements (Al, Ba, Ca, Co, Cu, Fe, K, Li, Mg, Mn, Mo, N, Nd, P, S, Sr and Ti) transfer from the mesocosm surface to the sediment traps installed at the base of the mesocosms after dust deposition show that (1) 15% of the initial dust mass was dissolved in the water column in the first 24 h after seeding. Except for Ca, S and N, the elemental composition of dust particles was constant during their settling, showing the relevance of using interelemental ratios, such as Ti / Al as proxy of lithogenic fluxes. (2) Whatever the type of seeding (using fresh dust to simulate dry deposition or artificially aged dust to simulate wet deposition), the particulate phase both in the water column and in the sediment traps was dominated by dust particles. (3) Due to the high Ba content in dust, Ba / Al cannot be used as productivity proxy in the case of high dust input in the sediment traps. Instead, our data suggests that the ratio Co / Al could be a good productivity proxy in this case. (4) After 7 days, between 30 and 68% of added dust was still in suspension in the mesocosms. This difference in the dust settling was directly associated with a difference in POC export, since POC fluxes were highly correlated to dust lithogenic fluxes signifying a ballast effect of dust. The highest fraction of remaining dust in suspension in the mesocosm at the end of the experiment was found inversely correlated to Chl a increase. This suggests that the fertilizing effect of dust on autotrophs organisms, the ballast effect, and POC fluxes are strongly correlated. (5) Our data emphasize a typical mass ratio Lithogenic / POC fluxes around 30 which could be used as reference to estimate the POC export triggered by wet dust deposition event. © Author(s) 2014."
"16507851200;57204253860;7004369046;","Total heating characteristics of the ISCCP tropical and subtropical cloud regimes",2013,"10.1175/JCLI-D-12-00673.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884243732&doi=10.1175%2fJCLI-D-12-00673.1&partnerID=40&md5=9c0b08ba2a67ba77d6a68eba99166dc4","Composite profiles of the apparent heat source Q1 and moisture sink Q2 are calculated for the International Satellite Cloud Climatology Project (ISCCP) cloud regimes (or ""weather states"") using sounding observations from 10 field campaigns comprising both tropical and subtropical domains. Distinct heating profiles were determined for each ISCCP cloud regime, ranging from strong, upper-tropospheric heating for mesoscale convective systems (WS1) to integrated cooling for populations typically associated with marine stratus and stratocumulus clouds (WS5, WS6, and WS7). Despite being primarily associated with thin cirrus, the corresponding regime (WS4) has heating maxima in the lower and midtroposphere due to the presence of underlying clouds. Regime-averagedQ2 profiles showed similar transitions with strong drying observed for deep convection and low-level moistening for marine boundary layer clouds. The derived profiles were generally similar over land and ocean with the notable exception of the fair-weather cumulus regime (WS8). Additional midlevel moistening was identified for several weather states over land, suggesting enhanced detrainment and more frequent congestus clouds compared to oceanic domains. Acontrol simulation using the Community Atmosphere Model, version 4 (CAM4), was similar to the largescale patterns of diabatic heating at low levels produced by the ISCCP composites. Differences were more pronounced at middle and upper levels and are largely attributed to the uncertainty in the heating profiles for the cumulus regime (WS8). Low-level heating anomalies were calculated for each phase of the Madden- Julian oscillation (MJO) and they precede upper-tropospheric heating from deep convection by 3-4 phases. Implications for future research using ISCCP heating reconstructions are also discussed. © 2013 American Meteorological Society."
"7201443624;6506416205;8982748700;8946494600;7102805852;","Examination of long-wave radiative bias in general circulation models over North Africa during may-july",2011,"10.1002/qj.717","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960717020&doi=10.1002%2fqj.717&partnerID=40&md5=d496d74b9f694fac5bc919f61964bee9","Satellite data are used to quantify and examine the bias in the outgoing long-wave (LW) radiation over North Africa during May-July simulated by a range of climate models and the Met Office global numerical weather prediction (NWP) model. Simulations from an ensemble-mean of multiple climate models overestimate outgoing clear-sky long-wave radiation (LWc) by more than 20 W m-2 relative to observations from Clouds and the Earth's Radiant Energy System (CERES) for May-July 2000 over parts of the west Sahara, and by 9 W m-2 for the North Africa region (20°W-30°E, 10-40°N). Experiments with the atmosphere-only version of the High-resolution Hadley Centre Global Environment Model (HiGEM), suggest that including mineral dust radiative effects removes this bias. Furthermore, only by reducing surface temperature and emissivity by unrealistic amounts is it possible to explain the magnitude of the bias. Comparing simulations from the Met Office NWP model with satellite observations from Geostationary Earth Radiation Budget (GERB) instruments suggests that the model overestimates the LW by 20-40 W m-2 during North African summer. The bias declines over the period 2003-2008, although this is likely to relate to improvements in the model and inhomogeneity in the satellite time series. The bias in LWc coincides with high aerosol dust loading estimated from the Ozone Monitoring Instrument (OMI), including during the GERBILS field campaign (18-28 June 2007) where model overestimates in LWc greater than 20 W m-2 and OMI-estimated aerosol optical depth (AOD) greater than 0.8 are concurrent around 20°N, 0-20°W. A model-minus-GERB LW bias of around 30 W m-2 coincides with high AOD during the period 18-21 June 2007, although differences in cloud cover also impact the model-GERB differences. © Royal Meteorological Society and Crown, 2010."
"42062002500;7004003763;22953316500;6602111828;","Trade wind cloud evolution observed by polarization radar: Relationship to giant condensation nuclei concentrations and cloud organization",2011,"10.1175/2010JAS3675.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79958761701&doi=10.1175%2f2010JAS3675.1&partnerID=40&md5=4410abcdc775918c13fca36cd40026d4","Shallow marine trade wind cumuli are one of the most prevalent cloud types in the tropical atmosphere. Understanding how precipitation forms within these clouds is necessary to advance our knowledge concerning their role in climate. This paper presents a statistical analysis of the characteristic heights and times at which precipitation in trade wind clouds passes through distinct stages in its evolution as defined by the equivalent radar reflectivity factor at horizontal polarization ZH, the differential reflectivity ZDR, and the spatial correlation between and averages of these variables. The data were obtained during the Rain in Cumulus over the Ocean (RICO) field campaign by the National Center for Atmospheric Research (NCAR) S-band dual-polarization (S-Pol) Doppler radar, the National Science Foundation (NSF)-NCAR C130 aircraft, and soundings launched near the radar. The data consisted of 76 trade cumuli that were tracked from early echo development through rainout on six days during RICO. Trade wind clouds used in the statistical analyses were segregated based on giant condensation nuclei (GCN) measurements made during low-level aircraft flight legs on the six days. This study found that the rate of precipitation formation in shallow marine cumulus was unrelated to the GCN concentration in the ambient environment. Instead, the rate at which precipitation developed in the clouds appeared to be related to the mesoscale forcing as suggested by the cloud organization. Although GCN had no influence on the rate of precipitation development, the data suggest that they do contribute to a modification of the rain drop size distribution within the clouds. With very few exceptions, high threshold values ofZDR were found well above cloud base on days with high GCN concentrations. On the days that were exceptions, these threshold values were almost always achieved near cloud base. © 2011 American Meteorological Society."
"36337661700;7801634218;36452770400;24822972000;35361180100;","A new three-dimensional visualization system for combining aircraft and radar data and its application to RICO observations",2010,"10.1175/2009JTECHA1395.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955541792&doi=10.1175%2f2009JTECHA1395.1&partnerID=40&md5=fff683725332c4a893f9e38d762b663d","The analysis of diverse datasets from meteorological field campaigns often involves the use of separate 1D or combined 2D plots from various applications, making the determination of spatial and temporal relationships and correlations among these data, and the overall synthesis of information, extremely challenging. Presented here is a new 3D visualization tool, the Aircraft and Radar Data Collocation and Analysis in 3D (ARCA3D), that can combine data collected from different sources and at different scales, utilizing advanced visualization and user interface techniques, which allows for easier comparison and synthesis of such disparate data. The 3D tool is demonstrated with aircraft-based microphysical probe data and ground-based dual-polarization radar data all collected during the Rain in Cumulus over the Ocean (RICO) field campaign. The 3D volumes of radar data can be interactively selected and quantitatively probed, while aircraftmeasured variables can be viewed along the aircraft track plotted within the 3D radar volumes or plotted as time series within regions of interest relative to the radar echoes. The greatest benefits of the new software, the 3D viewing of large radar and aircraft datasets with user-driven controls, are difficult to communicate here in a static, 2D written medium, but the application of the tool toward a research problem is presented to elucidate the impacts of these benefits. The ARCA3D software is used to investigate the possible role of giant aerosol particles in the development of precipitation in trade wind cumuli. The temporal trends in the spatial location of the maximum differential reflectivity echoes within the clouds are examined with respect to the ambient giant aerosol number concentration and the measured cloud-base droplet number concentrations on 10 days. The results indicate that in trade wind cumuli of sufficient depth, giant aerosol may determine the original location of the earliest differential reflectivity maximum echo, and thus the first raindrops when present in higher number concentrations. However, when the giant aerosol are less plentiful, the number of cloud droplets activated above the cloud base may also play a role in determining the location of the earliest maximum differential reflectivity echo, and thus the earliest raindrops, in these trade wind cumuli. © 2010 American Meteorological Society."
"55467486100;9536598800;57203492395;21735369200;6701469150;","A comparison of roll and nonroll convection and the subsequent deepening moist convection: An LEM case study based on SCMS data",2009,"10.1175/2008MWR2450.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-64149098249&doi=10.1175%2f2008MWR2450.1&partnerID=40&md5=b7e35e42e0445695eed7013019536a4c","Rolls observed during the Small Cumulus Microphysical Study (SCMS) field campaign are simulated using a large eddy model (LEM). The simulated boundary layer properties were in a good agreement with sounding profiles and aircraft observations, and the observed boundary layer rolls were reproduced by the model. Rolls started to decay when -Zi/L exceeded a threshold, with a value between 5 and 45. Here Zi and L refer to the height of the top of convective boundary layer and the Monin-Obukhov length, respectively. This value was found to depend on a nondimensional combination of the low-level wind shear, the height of the CBL, and the eddy velocity scale. Larger surface buoyancy fluxes and smaller shears gave higher thresholds. For the case modeled, rolls persisted for surface buoyancy fluxes less than 110 W m-2, and formed for boundary layer wind shears greater than 5 × 10-3 s-1, which is consistent with previous studies. The simulated roll convection was compared with a nonroll simulation, which was identical except for the wind and the wind shear used. In both the roll and nonroll cases the variability in convective inhibition (CIN) was dominated by the variability in the source air, rather than the lifting of the top of the boundary layer by the convection. Stronger moist updrafts existed in the nonroll convection, whereas roll convection gave a more symmetrical distribution of up and downdrafts, with stronger downdrafts than the nonroll case. The nonroll convection simulations have lower minimum values of CIN and clouds develop 15 min earlier in this case. © 2009 American Meteorological Society."
"12803465300;7403931916;7201826462;7005729142;","Relationship between ice water content and equivalent radar reflectivity for clouds consisting of nonspherical ice particles",2008,"10.1029/2008JD009890","https://www.scopus.com/inward/record.uri?eid=2-s2.0-58149265036&doi=10.1029%2f2008JD009890&partnerID=40&md5=a16eea2e63fe03d97e980e4de8acbcac","This study investigates the relationship between ice water content (IWC) and equivalent radar reflectivity (Z<inf>e</inf>) at 94 GHz for clouds consisting of nonspherical ice particles with geometrical shapes of hexagonal solid and hollow columns, plates, 6-branch bullet rosettes, aggregates, and droxtals. The IWC is calculated from a set of 1119 ice particle size distributions (PSDs) measured during several field campaigns, which are discretized to 46 size bins based on particle maximum dimensions ranging from 2 to 10500 μm. The Z<inf>e</inf> at 94 GHz is calculated from the radar backscattering properties obtained by integrating over the PSD and chosen particle habit distributions. The influence of ice habit on the Z<inf>e</inf>-IWC relationship is investigated for ice clouds composed of individual ice particle habits and a habit mixture. The Z<inf>e</inf>-IWC relationship is found to be sensitive to cloud effective particle size and cloud temperature. For an ice cloud with a given IWC, the Z<inf>e</inf> tends to increase with increasing effective particle size. Similarly, the Z<inf>e</inf> generally increases with increasing cloud temperature, at least for clouds with IWC over 0.01 g/m3. These features are consistent with the observed relationship between effective particle sizes and cloud temperatures. The present investigation of the effect of temperature on the Z<inf>e</inf>-IWC relationship indicates that including temperature in the Z<inf>e</inf>-IWC relationship may not improve the estimates of IWC. However, the dependence of the Z<inf>e</inf>-IWC relationship on the effective particle size within a given temperature range is more pronounced, and may be potentially useful for inferring the cloud effective particle size from the Z<inf>e</inf>-IWC relationship. Copyright 2008 by the American Geophysical Union."
"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."
"6603577857;7003566416;57214957433;6506314069;56251307100;7102496779;7005287667;6506390873;7004239300;7006377579;57195257572;7003377899;7007053654;7005140302;","Field validation of the droplet aerosol analyser",1997,"10.1016/S1352-2310(96)00183-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030616225&doi=10.1016%2fS1352-2310%2896%2900183-5&partnerID=40&md5=ddab12c13824a3d29c5ab89b8652ba0a","A new instrument for the study of cloud droplets and its relation to aerosol particles, the droplet aerosol analyser (DAA), was for the first time used in a field campaign. The DAA has the unique feature of measuring the ambient size of cloud droplets or cloud interstitial aerosol particles together with the size of its dry residue. This is obtained with a two-parameter data acquisition technique which results in a three-dimensional data set (ambient size, dry residue size, number concentration). The principle and design of the DAA is briefly described. The DAA was intercompared with differential mobility particle sizers, particulate volume monitors and a forward scattering spectrometer probe with respect to interstitial and cloud droplet dry residue size distribution as well as particle-size-dependent scavenging due to cloud droplet nucleation and for cloud droplet number concentration and size distribution and cloud liquid water concentration. Overall, the DAA showed good agreement with respect to all these six aerosol/cloud properties."
"7006746704;7202345493;6508257995;7006205166;","The frequency‐agile radar: A multifunctional approach to remote sensing of the ionosphere",1995,"10.1029/95RS01298","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029376451&doi=10.1029%2f95RS01298&partnerID=40&md5=46399d090d1363f60424269802c5f317","We introduce a new kind of diagnostic sensor that combines multifunctional measurement capabilities for ionospheric research. Multifunctionality is realized through agility in frequency selection over an extended band (1.5 to 50 MHz), system modularity, complete system control by software written in C, and a user‐friendly computer interface. This sensor, which we call the frequency‐agile radar (FAR), incorporates dual radar channels and an arbitrary waveform synthesizer that allows creative design of sophisticated waveforms as a means of increasing its sensitivity to weak signals while minimizing loss in radar resolution. The sensitivity of the FAR is determined by two sets of power amplifier modules: four 4‐kW solid‐state broadband amplifiers, and four 30‐kW vacuum tube amplifiers. FAR control is by an AT‐bus personal computer with on‐line processing by a programmable array processor. The FAR does not simply house the separate functions of most radio sensors in use today, it provides convenient and flexible access to those functions as elements to be used in any combination. Some of the first new results obtained with the FAR during recent field campaigns are presented to illustrate its versatility. These include (1) the first detection of anomalous high‐frequency (HF) reflections from a barium ion cloud, (2) the first evidence of unexpectedly large drifts and a shear north of the equatorial electrojet, (3) the first HF radar signature of a developing equatorial plasma bubble, and (4) the first measurements by a portable radar of altitude‐extended, quasi‐periodic backscatter from midlatitude sporadic E. We also mention the potential of the FAR for atmospheric remote sensing. Copyright 1995 by the American Geophysical Union."
"7005228425;","The Po Valley Fog Experiment 1989. What have we learned, where do we go from here?",1992,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027100074&partnerID=40&md5=7ea4be82ae0658e3d047001602dd37ee","In this special issue of Tellus B, results of the first of a series of joint European field campaigns concerning ground-base cloud experiments (GCE) are reported. The present paper illuminates the background of the experiment before giving answers to the questions of what GCE did achieve in the Po Valley experiment, what lessons have been learned on the way and where ground-based cloud research does go from here. -Author"
"36624257700;55924208000;","Ensemble superparameterization versus stochastic parameterization: A comparison of model uncertainty representation in tropical weather prediction",2017,"10.1002/2016MS000857","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019839431&doi=10.1002%2f2016MS000857&partnerID=40&md5=10d8b2e2f842e95d3ef0b8d19e259edf","Stochastic schemes to represent model uncertainty in the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble prediction system has helped improve its probabilistic forecast skill over the past decade by both improving its reliability and reducing the ensemble mean error. The largest uncertainties in the model arise from the model physics parameterizations. In the tropics, the parameterization of moist convection presents a major challenge for the accurate prediction of weather and climate. Superparameterization is a promising alternative strategy for including the effects of moist convection through explicit turbulent fluxes calculated from a cloud-resolving model (CRM) embedded within a global climate model (GCM). In this paper, we compare the impact of initial random perturbations in embedded CRMs, within the ECMWF ensemble prediction system, with stochastically perturbed physical tendency (SPPT) scheme as a way to represent model uncertainty in medium-range tropical weather forecasts. We especially focus on forecasts of tropical convection and dynamics during MJO events in October–November 2011. These are well-studied events for MJO dynamics as they were also heavily observed during the DYNAMO field campaign. We show that a multiscale ensemble modeling approach helps improve forecasts of certain aspects of tropical convection during the MJO events, while it also tends to deteriorate certain large-scale dynamic fields with respect to stochastically perturbed physical tendencies approach that is used operationally at ECMWF. © 2017. The Authors."
"7005960178;6506848120;57212421121;7006471143;7402838215;7004740995;","HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: Background, design, setup, and first flight data",2017,"10.5194/amt-10-35-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009152484&doi=10.5194%2famt-10-35-2017&partnerID=40&md5=3c3fb9131615e08ec8718c85e9cafe06","The novel Hygrometer for Atmospheric Investigation (HAI) realizes a unique concept for simultaneous gas-phase and total (gas-phase + evaporated cloud particles) water measurements. It has been developed and successfully deployed for the first time on the German HALO research aircraft. This new instrument combines direct tunable diode laser absorption spectroscopy (dTDLAS) with a first-principle evaluation method to allow absolute water vapor measurements without any initial or repetitive sensor calibration using a reference gas or a reference humidity generator. HAI contains two completely independent dual-channel (closed-path, open-path) spectrometers, one at 1.4 and one at 2.6 μm, which together allow us to cover the entire atmospheric H2O range from 1 to 40 000 ppmv with a single instrument. Both spectrometers each comprise a separate, wavelength-individual extractive, closed-path cell for total water (ice and gas-phase) measurements. Additionally, both spectrometers couple light into a common open-path cell outside of the aircraft fuselage for a direct, sampling-free, and contactless determination of the gas-phase water content. This novel twin dual-channel setup allows for the first time multiple self-validation functions, in particular a reliable, direct, in-flight validation of the open-path channels. During the first field campaigns, the in-flight deviations between the independent and calibration-free channels (i.e., closed-path to closed-path and open-path to closed-path) were on average in the 2 % range. Further, the fully autonomous HAI hygrometer allows measurements up to 240 Hz with a minimal integration time of 1.4 ms. The best precision is achieved by the 1.4 μm closed-path cell at 3.8 Hz (0.18 ppmv) and by the 2.6 μm closed-path cell at 13 Hz (0.055 ppmv). The requirements, design, operation principle, and first in-flight performance of the hygrometer are described and discussed in this work. © Author(s) 2017."
"55801689800;26023688200;56737226500;55967153600;6603230487;57097521200;7003414581;","Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations",2016,"10.5194/acp-16-651-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957308872&doi=10.5194%2facp-16-651-2016&partnerID=40&md5=6977b649436179d91be554a06cc74cf9","Large eddy simulations (LESs) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Due to the presence of a topographically structured island surface in the domain center, the model setup has to be designed with open lateral boundaries. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude potential temperature perturbations. In this work, this method is for the first time tested and validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE field campaign is used for both model initialization and a comparison with Doppler wind and Raman lidar data. Several numerical sensitivity tests are carried out to demonstrate the problems related to gray zone modelingg when using coarser spatial grid spacings beyond the inertial subrange of three-dimensional turbulence or when the turbulent marine boundary layer flow is replaced by laminar winds. Especially cloud properties in the downwind area west of Barbados are markedly affected in these kinds of simulations. Results of an additional simulation with a strong trade-wind inversion reveal its effect on cloud layer depth and location. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z g‰ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with wind lidar data show similarities in the downwind vertical wind structure. Additionally, the model results accurately reproduce the development of the daytime convective boundary layer measured by the Raman lidar. © Author(s) 2016."
"12800966700;57190422776;57202425542;8657166100;11440520800;6506454031;35572096100;57190428711;36573180000;57190425119;","HAIC/HIWC field campaigns - Specific findings on ice crystals characteristics in high ice water content cloud regions",2016,"10.2514/6.2016-4056","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088070380&doi=10.2514%2f6.2016-4056&partnerID=40&md5=7a2a6e88ca9d635d4cd854b2e184e097","The High Altitude Ice Crystals (HAIC) and High Ice Water Content (HIWC) projects aim at enhancing aircraft safety when flying in mixed phase and glaciated icing conditions. In order to better document such atmospheric conditions, two aircraft field campaigns have been conducted out of Darwin (Australia) in 2014 and Cayenne (French Guiana) in 2015, using specific instrumentation that allows accurate measurements of both the Total Water Content (TWC) and the individual ice particle characteristics. Ice crystal images have been analyzed in order to provide particle and mass size distributions as well as Median Mass Diameters (MMD). The Cayenne dataset complements the Darwin dataset through sampling the same temperature levels at a different location, providing identical measurements for comparison of trends in cloud particle microphysics. The Cayenne measurements confirm two trends observed for the Darwin dataset: MMDs decrease with increasing TWC (at all flight levels) and also with decreasing temperatures. In addition, the analysis of the Particle Size Distributions from Darwin and Cayenne shows that changes in temperature/altitude affect the concentrations of the smallest and the largest ice crystals in opposite ways in high IWC regions. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA."
"7102591209;24168416900;6602350870;6603735878;7004028051;6602087140;","On the relationship between the scattering phase function of cirrus and the atmospheric state",2015,"10.5194/acp-15-1105-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84922032754&doi=10.5194%2facp-15-1105-2015&partnerID=40&md5=2f009dee95deff25e07846fd19961b5e","This is the first paper to investigate the relationship between the shape of the scattering phase function of cirrus and the relative humidity with respect to ice (RHi, using space-based solar radiometric angle-dependent measurements. The relationship between RHi and the complexity of ice crystals has been previously studied using data from aircraft field campaigns and laboratory cloud chambers. However, to the best of our knowledge, there have been no studies to date that explore this relationship through the use of remotely sensed space-based angle-dependent solar radiometric measurements. In this paper, one case study of semi-transparent cirrus, which occurred on 25 January 2010 off the north-east coast of Scotland, is used to explore the possibility of such a relationship. Moreover, for the first time, RHi fields predicted by a high-resolution numerical weather prediction (NWP) model are combined with satellite retrievals of ice crystal complexity. The NWP model was initialised at midnight, on 25 January 2010, and the mid-latitude RHi field was extracted from the NWP model at 13:00 UTC. At about the same time, there was a PARASOL (Polarization and Anisotropy of Reflectance for Atmospheric science coupled with Observations from a Lidar) overpass, and the PARASOL swath covered the NWP-model-predicted RHi field. The cirrus case was located over Scotland and the North Sea. From the satellite channel based at 0.865 Î1/4m, the directionally averaged and directional spherical albedos were retrieved between the scattering angles of about 80 and 130°. An ensemble model of cirrus ice crystals is used to predict phase functions that vary between phase functions that exhibit optical features (referred to as pristine) and featureless phase functions. For each of the PARASOL pixels, the phase function that best minimised differences between the spherical albedos was selected. This paper reports, for this one case study, an association between the most featureless phase function model and the highest values of NWP-predicted RHi (i.e. when RHi &gt; 1.0). For pixels associated with NWP-model-predicted RHi &lt; 1, it was impossible to generally discriminate between phase function models at the 5% significance level. It is also shown that the NWP model prediction of the vertical profile of RHi is in good agreement with dropsonde, in situ measurements and independent aircraft-based physical retrievals of RHi. Furthermore, the NWP model prediction of the cirrus cloud-top height and its vertical extent is also found to be in good agreement with aircraft-based lidar measurements. © 2015 Author(s)."
"26632168400;36243762400;6603431534;","Vertical velocities and turbulence in midlatitude anvil cirrus: A comparison between in situ aircraft measurements and ground-based Doppler cloud radar retrievals",2014,"10.1002/2014GL062279","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923329824&doi=10.1002%2f2014GL062279&partnerID=40&md5=73addd7e8b9b8e06c5a4c235a585d462","This study introduces a statistical comparison of vertical velocity observations within cirrus from aircraft and ground-based Doppler cloud radar. Two cases of midlatitude anvil cirrus forming under very similar environmental conditions are examined. The case studies benefit from simultaneous observations of vertical velocities in cirrus collected at and around the Atmospheric Radiation Measurement Southern Great Plains site during the U.S. Department of Energy Small Particles in Cirrus field campaign. Observations from both platforms suggest that the majority of vertical velocities in the examined midlatitude anvil cirrus cases are roughly within ±1 m s-1 although higher vertical velocities are occasionally observed. The quality of the vertical velocity comparison between in situ aircraft measurements and ground-based Doppler radar retrievals depends on the case. For the first case on 23 April 2010, the comparison suggests that the radar retrieval may underestimate vertical velocities in the range between roughly 50 cm s-1 and 1 m s-1. For the second case on 14 June 2010, the agreement between radar and aircraft is excellent, and the differences are largely within the observed variability of vertical velocities within cirrus. Differences in the spatial scales of vertical velocities and turbulence sampled by the aircraft and Doppler radar, which arise due to differences in the temporal resolution of the observational platforms are not found to explain the observed discrepancies. Estimates for the dissipation rate of turbulent kinetic energy agree to within 1 order of magnitude between the two observational platforms. © 2014. American Geophysical Union. All Rights Reserved."
"55714855400;55363002500;","Automatic sea fog detection over Chinese adjacent oceans using Terra/MODIS data",2014,"10.1080/01431161.2014.968685","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84915815416&doi=10.1080%2f01431161.2014.968685&partnerID=40&md5=b78f28dc9782629da9d2d49924b9b53c","Sea fog is a problematic weather phenomenon for marine transportation and navigation. Lacking ground observations, sea fog monitoring mainly depends on meteorological and environmental satellites because they provide large swaths of data with good spatial and temporal resolution. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellites provides several new features for sea fog detection because of the more available channels.In addition to the traditional variable-dual channel difference (DCDIR), which is widely used to detect sea fog and stratus clouds at night, this study uses and analyses several other variables including NDSI (normalized difference snow index), BTDback (brightness temperature difference in the thermal infrared channel between a sea fog/stratus cloud pixel and nearby clear-sky ocean surface), NWVI (normalized difference near-infrared water vapour index) and D_NWVI (NWVI difference between a possible sea fog/stratus cloud pixel and nearby clear-sky ocean surface), for all seasons. BTDback, NWVI, and D_NWVI show outstanding ability to discriminate between sea fog and stratus clouds. Automatic sea fog detection algorithms are developed using these variables for both daytime and night time with Terra/MODIS data based on a threshold scheme. During development of the algorithms, a series of data processes are also considered to maintain stable performance of the algorithms over wide areas and in all seasons.The algorithms are applied to Terra/MODIS data at a semi-operational mode from 2007 to 2013 and show promising results. Validation with data from field campaigns, one buoy station with good maintenance, 18 weather stations, and CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization)/CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) demonstrates the accuracy of the algorithms. The sea fog detection results are highly consistent with fog observations from the field campaign data. The validation with the buoy station data shows an overall accuracy of 90% under all weather conditions, an accuracy of 86% during foggy weather condition, and a KSS (Hanssen–Kuiper Skill Score) of 0.81. The validation with two-year data from 18 weather stations and CALIOP/CALIPSO over the Bohai Sea and Yellow Sea shows accuracy of 76.3% and 77.9%, respectively. The promising results indicate high probability of applying the algorithms in operational systems over the oceans adjacent to China or even wider oceans using Terra/MODIS data. © 2014, © 2014 Taylor & Francis."
"55630942000;7103016965;9044746800;","Using operational weather radar to assess high-resolution numerical weather prediction over the British Isles for a cold air outbreak case-study",2014,"10.1002/qj.2123","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84922810434&doi=10.1002%2fqj.2123&partnerID=40&md5=9717443606265c7fff3f1525a22e1a1e","Examination of weather radar data from the Constrain field campaign during January 2010 is presented, and comparisons between the radar data and reflectivity data computed from the Met Office high-resolution British Isles NWP model (UKV Δx = 1.5 km) are shown. Cluster analysis was used to identify and track cells of precipitation in the two datasets; this allowed characteristics of the cloud field to be examined. Cells of precipitation were identified in the data using a reflectivity threshold of 10 dBz which allowed these cells to be tracked as they moved through the region of interest. The mean cell area identified in the radar data was found to be 37.5±1.3 km2, while the mean area of cells identified in the model data was 63.5±2.0 km2. Significant differences between the model and radar data were seen in the shape of the cells, with the cells identified in the model found to be more circular than those seen in the radar data. © 2013 John Wiley & Sons Ltd."
"6603812137;21739916500;24779895300;","Characteristics of lightning related to wildfire ignitions in Catalonia",2014,"10.1016/j.atmosres.2012.07.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889603614&doi=10.1016%2fj.atmosres.2012.07.011&partnerID=40&md5=469b4be5a42b80b73ad84782b284b810","What are the characteristics of lightning that influence the probability that an individual stroke will ignite a wildfire? It is generally accepted that long continuing current following some return strokes is the cause of ignition in forest fuels. However, because these low-level currents are not detectable with operative Lightning Location Systems, other lightning characteristics correlating with its occurrence have been proposed and used to estimate ignition probability. These variables are typically: flash multiplicity, stroke polarity, stroke peak current and flash interstroke interval. The region of Catalonia is prone to forest fires, and to set a probability of ignition to each cloud-to-ground flash could be useful in wildfire management. A set of more than 500 lightning-ignited wildfires that occurred in Catalonia between 2004 and 2009 was analyzed, in order to find which flash/stroke characteristics are related to ignition. Lightning activity was gathered by the Lightning Location System of the Meteorological Service of Catalonia. Lightning related to these wildfires were selected from the lightning database using a proximity index. The statistical analysis has shown that the sample of lightning causing ignition does not present any characteristic that differentiates it from the overall population. Polarity percents, multiplicity and peak current frequency distributions in the lightning causing ignition set are similar to the climatological ones. Besides this analysis, a high-speed video field campaign of natural lightning recordings was conducted, to obtain new insight into the characteristics of lightning bearing a continuing current. Video analysis has shown that almost each kind of cloud-to-ground (CG) flash (negative, positive, single or multiple stroke) can have a continuing current component. Only negative strokes with peak currents above 20. kA were not followed by long continuing current. These results are similar to studies carried out in other regions. © 2012 Elsevier B.V."
"23491820700;7004003763;6602111828;","A revised conceptual model of the tropical marine boundary layer. Part II: Detecting relative humidity layers using bragg scattering from S-band radar",2013,"10.1175/JAS-D-12-0322.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885905413&doi=10.1175%2fJAS-D-12-0322.1&partnerID=40&md5=1f2dc36f5ae3c4b622a91fcada9187eb","Persistent layers of enhanced equivalent radar reflectivity factor and reduced spectral width were commonly observed within cloud-free regions of the tropical marine boundary layer (TMBL) with the National Center for Atmospheric Research S-Pol radar during the Rain in Cumulus over the Ocean (RICO) field campaign. Bragg scattering is shown to be the primary source of these layers. Two mechanisms are proposed to explain the Bragg scattering layers (BSLs), the first involving turbulent mixing and the second involving detrainment and evaporation of cloudy air. These mechanisms imply that BSLs should exist in layers with tops (bases) defined by local relative humidity (RH) minima (maxima). The relationship between BSLs and RH is explored. An equation for the vertical gradient of radio refractivity N is derived, and a scale analysis is used to demonstrate the close relationship between verticalRHandNgradients. This is tested using the derived radar BSL boundary altitudes, 131 surface-based soundings, and 34 sets of about six near-coincident, aircraftreleased dropsondes. First, dropsonde data are used to quantify the finescale variability of theRHfield. Then, within limits imposed by this variability, altitudes of tops (bases) of radar BSLs are shown to agree with altitudes of RH minima (maxima). These findings imply that S-band radars can be used to track the vertical profile of RH variations as a function of time and height, that the vertical RH profile of the TMBL is highly variable over horizontal scales as small as 60 km, and that BSLs are a persistent, coherent feature that delineate aspects of TMBL mesoscale structure. © 2013 American Meteorological Society."
"55114616400;7101867299;6701518904;","Horizontal structure function and vertical correlation analysis of mesoscale water vapor variability observed by airborne lidar",2013,"10.1002/jgrd.50588","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882804928&doi=10.1002%2fjgrd.50588&partnerID=40&md5=0c517cbfa39848ca06bf27a2291a721c","Analysis is presented of airborne lidar measurements of water vapor, covering a height range from 1.5 to 10.4 km, from three field campaigns (midlatitude summer, polar winter, and subtropical summer). The lidar instrument provides two-dimensional cross sections of absolute humidity, with high accuracy (errors less than 5-7%) and high vertical (∼ 200 m) and horizontal (∼ 2 km) resolution. Structure functions, i.e., statistical moments up to the fifth-order of absolute increments over a range of scales, are investigated, and power law scaling or statistical-scale invariance was found over horizontal distances from 5 to 100 km. The scaling exponents are found to take different values, depending on whether or not the observations were taken in an air mass where convective clouds were present. The exponent of the first-order structure function in nonconvective regions, H=0.63±0.10, is large indicating a smooth series with long-range correlations, in contrast to the lower value H=0.35±0.11 found in convective air masses. Correspondingly, the moisture field in the convective regime was found to be more intermittent than for the nonconvective regime, i.e., water vapor structures in convectively influenced air mass show more jump discontinuities, which could be explained by the moistening and drying effects of updrafts and downdrafts in convective air mass. Within each regime (convective or nonconvective), the values appear to be universal, with no significant dependence on the season, latitude, or height where the observations were made. Furthermore, some evidence is found that vertical correlation lengths are longer in convective air masses. Key Points Mesoscale water vapor variability including the subgrid scale is characterized Scaling exponents in convective airmass are lower than in non-convective Correlation length in convective airmass is longer than in non-convective ©2013. American Geophysical Union. All Rights Reserved."
"7004159166;7006930059;16833315000;7006960661;25522357400;6602914876;6601943623;","Evaluation of simulated aerosol properties with the aerosol-climate model ECHAM5-HAM using observations from the IMPACT field campaign",2010,"10.5194/acp-10-7709-2010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955928329&doi=10.5194%2facp-10-7709-2010&partnerID=40&md5=977ed9bed0ce2f533945e1a3bb5bbe05","In May 2008, the measurement campaign IMPACT for observation of atmospheric aerosol and cloud properties was conducted in Cabauw, The Netherlands. With a nudged version of the coupled aerosol-climate model ECHAM5-HAM we simulate the size distribution and chemical composition of the aerosol and the associated aerosol optical thickness (AOT) for the campaign period. Synoptic scale meteorology is represented realistically through nudging of the vorticity, the divergence, the temperature and the surface pressure. Simulated concentrations of aerosol sulfate and organics at the surface are generally within a factor of two from observed values. The monthly averaged AOT from the model is 0.33, about 20% larger than observed. For selected periods of the month with relatively dry and moist conditions discrepancies are approximately ĝ̂'30% and +15%, respectively. Discrepancies during the dry period are partly caused by inaccurate representation of boundary layer (BL) dynamics by the model affecting the simulated AOT. The model simulates too strong exchange between the BL and the free troposphere, resulting in weaker concentration gradients at the BL top than observed for aerosol and humidity, while upward mixing from the surface layers into the BL appears to be underestimated. The results indicate that beside aerosol sulfate and organics also aerosol ammonium and nitrate significantly contribute to aerosol water uptake. The simulated day-to-day variability of AOT follows synoptic scale advection of humidity rather than particle concentration. Even for relatively dry conditions AOT appears to be strongly influenced by the diurnal cycle of RH in the lower boundary layer, further enhanced by uptake and release of nitric acid and ammonia by aerosol water. © Author(s) 2010."
"23995016900;6701590980;","A numerical study of the evolving convective boundary layer and orographic circulation around the Santa Catalina Mountains in Arizona. Part I: Circulation without deep convection",2010,"10.1175/2009MWR3098.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955569453&doi=10.1175%2f2009MWR3098.1&partnerID=40&md5=7693354c4cbaf2c6fdcb4d2a07401a16","The daytime evolution of the thermally forced boundary layer (BL) circulation over an isolated mountain, about 30 km in diameter and 2 km high, is examined by means of numerical simulations validated with data collected in the Cumulus Photogrammetric, In Situ, and Doppler Observations (CuPIDO) field campaign. Two cases are presented, one remains cloud free in the simulations, and the second produces orographic convection just deep enough to yield a trace of precipitation. The Weather Research and Forecasting version 3 simulations, at a resolution of 1 km, compare well with CuPIDO observations. The simulations reveal a solenoidal circulationmostly containedwithin the convectiveBL, but this circulation and especially its upper-level return flow branch are not immediately apparent since they are overwhelmed by BL thermals. A warm anomaly forms over the high terrain during the day, but it is rather shallow and does not extend over the depth of the convective BL, which bulges over the mountain. Low-level mountain-scale convergence (MSC), driven by an anabatic pressure gradient, deepens during the day. Even relatively shallow and relatively small cumulus convection can temporarily overwhelm surface MSC by cloud shading and convective downdraft dynamics. In the evening drainage flow develops near the surface before the anabatic forcing ceases, and anabatic flow is still present in the residual mixed layer, decoupled from the surface. The interaction of the boundary layer circulation with deep orographic convection is examined in Part II of this study. © 2010 American Meteorological Society."
"9537045600;10144312200;57196933120;7004167838;","Characterization of precipitating clouds by ground-based measurements with the triple-frequency polarized Microwave Radiometer ADMIRARI",2010,"10.1175/2009JAMC2340.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953511851&doi=10.1175%2f2009JAMC2340.1&partnerID=40&md5=e14696f98d0bc8b4b0bc88dd9123051f","A groundbreaking new-concept multiwavelength dual-polarized Advanced Microwave Radiometer for Rain Identification (ADMIRARI) has been built and continuously operated in two field campaigns: the Convective and Orographically Induced Precipitation Study (COPS) and the European Integrated Project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI). The radiometer has 6 channels working in horizontal and vertical polarization at 10.65, 21.0, and 36.5 GHz, and it is completely steerable both in azimuth and in elevation. The instrument is suited to be operated in rainy conditions and is intended for retrieving simultaneously water vapor, rain, and cloud liquid water paths. To this goal the authors implemented a Bayesian retrieval scheme based on many state realizations simulated by the Goddard Cumulus Ensemble model that build up a prior probability density function of rainfall profiles. Detailed three-dimensional radiative transfer calculations, which account for the presence of nonspherical particles in preferential orientation, simulate the downwelling brightness temperatures and establish the similarity of radiative signatures and thus the probability that a given profile is actually observed. Particular attention is devoted to the sensitivity of the ADMIRARI signal to 3D effects, raindrop size distribution, and axial ratio parameterizations. The polarization and multifrequency signals represent key information to separate the effects introduced by non-Rayleigh scatterers and to separate rainwater (r-LWP) from the cloud water component (c-LWP). Longterm observations demonstrate that observed brightness temperatures and polarization differences can be well interpreted and reproduced by the simulated ones for all three channels simultaneously. Rough estimates of r-LWP derived from collocated observations with a micro rain radar confirm the rain/no rain separation and the variability trend of r-LWP provided by the radiometer-based retrieval algorithm. With this work the authors demonstrate the potential of ADMIRARI to retrieve information about the rain/cloud partitioning for midlatitude precipitation systems; future studies with this instrument will provide crucial information on rain efficiency of clouds for cloud modelers that might lead toward a better characterization of rain processes. © 2010 American Meteorological Society."
"57218944645;","4D-Var assimilation of MERIS total column water-vapour retrievals over land",2009,"10.1002/qj.509","https://www.scopus.com/inward/record.uri?eid=2-s2.0-70350675098&doi=10.1002%2fqj.509&partnerID=40&md5=b88b1aeaa431726b26d5e44ca3f4b369","Experiments with the active assimilation of total column water-vapour retrievals from Envisat MERIS observations have been performed at the European Centre for Medium-Range Weather Forecasts (ECMWF), focusing on the summer 2006 African Monsoon Multidisciplinary Analysis (AMMA) field campaign period. A mechanism for data quality control, observation error definition and variational bias correction has been developed so that the data can be safely treated within 4D-Var, like other observations that are currently assimilated in the operational system. While data density is limited due to the restriction to daylight and cloud-free conditions, a systematic impact on mean moisture analysis was found, with distinct regional and seasonal features. The impact can last 1-2 days into the forecast but has little effect on forecast accuracy in terms of both moisture and dynamics. This is mainly explained by the weak dynamic activity in the areas of largest data impact. Analysis and short-range forecast evaluation with radiosonde observations revealed a strong dependence on radiosonde type. Compared with Vaisala RS92 observations, the addition of MERIS total column watervapour observations produced neutral to positive impact, while contradictory results were obtained when all radiosonde types were used in generating the statistics. This highlights the issue of radiosonde moisture biases and the importance of sonde humidity bias correction in numerical weather prediction (NWP). © 2009 Royal Meteorological Society."
"7006061457;","Cloud phase structure: Experimental data analysis and parameterization",2006,"10.1175/JAS3660.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33645099291&doi=10.1175%2fJAS3660.1&partnerID=40&md5=e7f63cd9a2bd430b0a345cfb97cacfa8","In this article, the data collected over 6 yr of daily observations at a network of aircraft sounding (31 stations) in the former Soviet Union, and the data collected by Canadian researchers in field campaigns in the 1990s, are reanalyzed and compared with each other. To describe the cloud phase structure (CPS), the notion of the cloud phase index (CPI)3 is used; that is, the local mass fraction of the ice particles in the total (water + ice) water content. It is concluded that the average distribution of the (CPI)3 values in clouds depends mainly on the temperature, the cloud types, and the scale of averaging. If these characteristics remain unchanged the geographic and seasonal variations of the phase structure are small. It is shown that for averaging scales of the order of 100 m, the frequency of occurrence of liquid clouds [(CPI)3 = 0] varies from approximately 60% at 0°C to 5% at -35°C, and that of the ice clouds from about 5% to 60%. The frequency of occurrence of the mixed clouds only weakly depends on temperature, varying within 30%-40%. The dependence of the cumulative (CPI)3 distribution on temperature in the interval 0.1 &lt; (CPI)3, &lt; 0.7 is close to linear. For stratiform clouds (without going into further details) the coefficients of the linear parameterization are found as a function of temperature. Knowing the (CPI)3 distribution allows one to also estimate the humidity in clouds. The most urgent challenges for the experimental studies of the cloud phase structure are formulated. © 2006 American Meteorological Society."
"52464731300;35494005000;","Retrieval of cirrus microphysical properties with a suite of algorithms for airborne and spaceborne lidar, radar, and radiometer data",2006,"10.1175/JAM2427.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846232257&doi=10.1175%2fJAM2427.1&partnerID=40&md5=648ef5e496b983e2784c012d672521ae","Algorithms are developed to convert data streams from multiple airborne and spaceborne remote sensors into layer-averaged cirrus bulk microphysical properties. Radiometers such as the Moderate-Resolution Imaging Spectroradiometer (MODIS) observe narrowband spectral radiances, and active remote sensors such as the lidar on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite and the millimeter radar on CloudSat will provide vertical profiles of attenuated optical backscatter and radar reflectivity. Equivalent airborne remote sensors are also routinely flown on the NASA WB-57F and ER-2 aircraft. Algorithms designed to retrieve cirrus microphysical properties from remote sensor data must be able to handle the natural variability of cirrus that can range from optically thick layers that cause lidar attenuation to tenuous layers that are not detected by the cloud radar. An approach that is adopted here is to develop an algorithm suite that has internal consistency in its formulation and assumptions. The algorithm suite is developed around a forward model of the observations and is inverted for layer-mean cloud properties using a variational technique. The theoretical uncertainty in the retrieved ice water path retrieval is 40%-50%, and the uncertainty in the layer-mean particle size retrieval ranges from 50% to 90%. Two case studies from the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) field campaign as well as ground-based cases from the Atmospheric Radiation Measurement Program (ARM) are used to show the efficacy and error characteristics of the algorithms. © 2006 American Meteorological Society."
"8524581100;55984424900;7005601996;7006354036;7005783253;","Partitioning of metals between the aqueous phase and suspended insoluble material in fog droplets",2005,"10.1002/adic.200590033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-20544447923&doi=10.1002%2fadic.200590033&partnerID=40&md5=d39412e35fab94cc6704d45529102581","This paper discusses the partitioning of metals (K, Na, Ca, Mg, Al, Cu, Fe, Pb and Zn) between the aqueous phase and the suspended insoluble material in fog samples collected in the Po Valley during two extensive fields campaigns. Metals represent on average 11% of the mass of suspended insoluble matter, while the main component is carbon (both organic carbon, OC = 35%, and black carbon, BC = 8%). The unaccounted suspended matter mass is very high, on average 46%, and is attributable to non metallic species, such as O and N and of Si. The principal metals in the insoluble suspended fraction are Fe and Al (2-5%), while the contributions of other metals (Na, Mg, Cu, Pb and Zn) are lower than 1%. Ca and K exhibited high blank values and could not be detected above blank detection limit threshold. The main components in the aqueous phase are NO 3- (34%), WSOC (23%), SO42- (18%) and NH4+ (19%), while trace metals and remaining cations and anions accounted for less than 1% of solute mass. The main dissolved trace metals in fog droplets are Zn, Al and Fe, while the main metallic cations are Na and Ca. Fe and Al are the only metals preferentially distributed in the suspended insoluble matter of fog droplets (partitioning ratio respectively 37% and 33%). All other metals are mostly dissolved in the aqueous phase (mean partitioning ratios of Mg, Pb, Zn, Cu and Na are 69%, 70%, 77%, 81% and 87%). These findings are in agreement with literature data on metal speciation in cloud and rain samples. The dependence of partitioning ratios on pH is investigated for the different metals, with only Al showing a clear partitioning ratio decrease with increasing pH. Conversely, the other metals show no dependence or a complex and highly variable behaviour. The partitioning ratio of iron (mean 37%) observed in the Po Valley fog samples is much higher than the water extractable iron in aerosol particles (typically 1-2 %): this fact can be explained by differences in the aerosol sources and composition among sites and by chemical processes in the aqueous phase, such as complexation and redox reactions involving organic ligands (oxalate, or other organic acids as humic-like organic matter) which may promote Fe solubility."
"7005941690;7006427289;7003796330;7003911760;","Inference of marine atmospheric boundary layer moisture and temperature structure using airborne lidar and infrared radiometer data",1998,"10.1175/1520-0450-37.3.308","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032029468&doi=10.1175%2f1520-0450-37.3.308&partnerID=40&md5=fbec6195ade773a0ed13cb24dfbdf885","A new technique for retrieving near-surface moisture and profiles of mixing ratio and potential temperature through the depth of the marine atmospheric boundary layer (MABL) using airborne lidar and multichannel infrared radiometer data is presented. Data gathered during an extended field campaign over the Atlantic Ocean in support of the Lidar In-space Technology Experiment are used to generate 16 moisture and temperature retrievals that are then compared with dropsonde measurements. The technique utilizes lidar-derived statistics on the height of cumulus clouds that frequently cap the MABL to estimate the lifting condensation level. Combining this information with radiometer-derived sea surface temperature measurements, an estimate of the near-surface moisture can be obtained to an accuracy of about 0.8 g kg-1. Lidar-derived statistics on convective plume height and coverage within the MABL are then used to infer the profiles of potential temperature and moisture with a vertical resolution of 20 m. The rms accuracy of derived MABL average moisture and potential temperature is better than 1 g kg-1 and 1°C, respectively. The method relies on the presence of a cumuluscapped MABL, and it was found that the conditions necessary for use of the technique occurred roughly 75% of the time. The synergy of simple aerosol backscatter lidar and infrared radiometer data also shows promise for the retrieval of MABL moisture and temperature from space."
"56321122100;57205156269;7102128820;6602515941;36458602300;","Retrievals of Riming and Snow Density From Vertically Pointing Doppler Radars",2018,"10.1029/2018JD028603","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058857826&doi=10.1029%2f2018JD028603&partnerID=40&md5=7ada51ab33eaf51b5f9b1b7312a65340","Retrievals of ice and snow are made from Ka- and W-band zenith-pointing Doppler radars at Hyytiälä, Finland, during the snow experiment component of the Biogenic Aerosols: Effects on Clouds and Climate (2014) field campaign. In a novel optimal estimation retrieval, mean Doppler velocity is exploited to retrieve a density factor parameter, which modulates the mass, shape, terminal velocity, and backscatter cross sections of ice particles. In a case study including aggregate snow and graupel we find that snow rate and ensemble mean ice density can be retrieved to within 50% of in situ measurements at the surface using dual-frequency Doppler radar retrievals. While Doppler measurements are essential to the retrieval of particle density, the dual-frequency ratio provides a strong constraint on particle size. The retrieved density factor is strongly correlated with liquid water path, indicating that riming is the primary process by which the density factor is modulated. Using liquid water path as a proxy for riming, profiles classified as unrimed snow, rimed snow, and graupel exhibit distinct features characteristic of aggregation and riming processes, suggesting the potential to make estimates of process rates from these retrievals. We discuss the potential application of the technique to future satellite missions. ©2018. American Geophysical Union. All Rights Reserved."
"55813858200;6701873414;57203233100;6701592014;","Antarctic Cloud Macrophysical, Thermodynamic Phase, and Atmospheric Inversion Coupling Properties at McMurdo Station: I. Principal Data Processing and Climatology",2018,"10.1029/2018JD028279","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048975028&doi=10.1029%2f2018JD028279&partnerID=40&md5=178a5050679024f5aa3b7b1d2ac866ce","Polar cloud radiative forcing plays a crucial role in the determination of the surface and atmospheric energy balance through processes which are not yet fully understood. While there is a broad and fairly complete database of cloud measurements from several Arctic sites and field campaigns through the past two decades, the recent one-year long U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) field campaign at McMurdo Station has provided a hitherto unmatched multiple-instrument set of ground-based Antarctic cloud measurements. These observations are processed and used to derive the main cloud and liquid containing layer properties: occurrence fraction, cloud persistence and boundaries, and configuration relative to temperature and moisture inversions. The results are compared to previous Arctic observations. It is concluded that clouds and liquid-bearing layers over McMurdo Station are essentially less prevalent and persistent than their Arctic counterparts. However, they typically have higher bases and show a weaker temperature dependence than in the Arctic, suggesting a more “pristine” Antarctic atmosphere. In addition, the clouds (including both water phases) typically extend toward relatively lower altitudes, and their relation to inversions near cloud top is often similar to those observed in the Arctic. ©2018. American Geophysical Union. All Rights Reserved."
"24759591600;8719703500;7006783796;35567153700;11440520800;6506234624;36842724800;7003475277;24322892500;6701754792;23017945100;","A prototype method for diagnosing high ice water content probability using satellite imager data",2018,"10.5194/amt-11-1615-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044403662&doi=10.5194%2famt-11-1615-2018&partnerID=40&md5=859aad272888ab5a7b16bcab7146a00c","Recent studies have found that ingestion of high mass concentrations of ice particles in regions of deep convective storms, with radar reflectivity considered safe for aircraft penetration, can adversely impact aircraft engine performance. Previous aviation industry studies have used the term high ice water content (HIWC) to define such conditions. Three airborne field campaigns were conducted in 2014 and 2015 to better understand how HIWC is distributed in deep convection, both as a function of altitude and proximity to convective updraft regions, and to facilitate development of new methods for detecting HIWC conditions, in addition to many other research and regulatory goals. This paper describes a prototype method for detecting HIWC conditions using geostationary (GEO) satellite imager data coupled with in situ total water content (TWC) observations collected during the flight campaigns. Three satellite-derived parameters were determined to be most useful for determining HIWC probability: (1) the horizontal proximity of the aircraft to the nearest overshooting convective updraft or textured anvil cloud, (2) tropopause-relative infrared brightness temperature, and (3) daytime-only cloud optical depth. Statistical fits between collocated TWC and GEO satellite parameters were used to determine the membership functions for the fuzzy logic derivation of HIWC probability. The products were demonstrated using data from several campaign flights and validated using a subset of the satellite-Aircraft collocation database. The daytime HIWC probability was found to agree quite well with TWC time trends and identified extreme TWC events with high probability. Discrimination of HIWC was more challenging at night with IR-only information. The products show the greatest capability for discriminating TWCĝ€ ≥ ĝ€0.5ĝ€gĝ€mĝ'3. Product validation remains challenging due to vertical TWC uncertainties and the typically coarse spatio-Temporal resolution of the GEO data. © 2018 Author(s)."
"55626983400;7403276577;35546736600;","Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures",2018,"10.5194/tc-12-907-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043992105&doi=10.5194%2ftc-12-907-2018&partnerID=40&md5=ee91177e4427a8bf9f7ca72296c2e0fb","As rapid warming of the Arctic occurs, it is imperative that climate indicators such as temperature be monitored over large areas to understand and predict the effects of climate changes. Temperatures are traditionally tracked using in situ 2 m air temperatures and can also be assessed using remote sensing techniques. Remote sensing is especially valuable over the Greenland Ice Sheet, where few ground-based air temperature measurements exist. Because of the presence of surface-based temperature inversions in ice-covered areas, differences between 2 m air temperature and the temperature of the actual snow surface (referred to as ""skin"" temperature) can be significant and are particularly relevant when considering validation and application of remote sensing temperature data. We present results from a field campaign extending from 8 June to 18 July 2015, near Summit Station in Greenland, to study surface temperature using the following measurements: skin temperature measured by an infrared (IR) sensor, 2 m air temperature measured by a National Oceanic and Atmospheric Administration (NOAA) meteorological station, and a Moderate Resolution Imaging Spectroradiometer (MODIS) surface temperature product. Our data indicate that 2 m air temperature is often significantly higher than snow skin temperature measured in situ, and this finding may account for apparent biases in previous studies of MODIS products that used 2 m air temperature for validation. This inversion is present during our study period when incoming solar radiation and wind speed are both low. As compared to our in situ IR skin temperature measurements, after additional cloud masking, the MOD/MYD11 Collection 6 surface temperature standard product has an RMSE of 1.0 °C and a mean bias of -0.4 °C, spanning a range of temperatures from -35 to -5 °C (RMSE Combining double low line 1.6 °C and mean bias Combining double low line -0.7 °C prior to cloud masking). For our study area and time series, MODIS surface temperature products agree with skin surface temperatures better than previous studies indicated, especially at temperatures below -20 °C, where other studies found a significant cold bias. We show that the apparent cold bias present in other comparisons of 2 m air temperature and MODIS surface temperature may be a result of the near-surface temperature inversion. Further investigation of how in situ IR skin temperatures compare to MODIS surface temperature at lower temperatures (below -35 °C) is warranted to determine whether a cold bias exists for those temperatures. © Author(s) 2018."
"55683878900;14035386400;56241364500;55914433400;57193496623;56183181400;6603180620;24465126800;56495287900;7004393835;57195325985;55554574300;8084443000;7005941217;7006837187;35551238800;6602999057;8657166100;","Assessing the role of anthropogenic and biogenic sources on PM1 over southern West Africa using aircraft measurements",2018,"10.5194/acp-18-757-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040938158&doi=10.5194%2facp-18-757-2018&partnerID=40&md5=06a04360883936549e6ff6b1e9c03453","As part of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project, an airborne campaign was designed to measure a large range of atmospheric constituents, focusing on the effect of anthropogenic emissions on regional climate. The presented study details results of the French ATR42 research aircraft, which aimed to characterize gas-phase, aerosol and cloud properties in the region during the field campaign carried out in June/July 2016 in combination with the German Falcon 20 and the British Twin Otter aircraft. The aircraft flight paths covered large areas of Benin, Togo, Ghana and Côte d'Ivoire, focusing on emissions from large urban conurbations such as Abidjan, Accra and Lomé, as well as remote continental areas and the Gulf of Guinea. This paper focuses on aerosol particle measurements within the boundary layer (< 2000 m), in particular their sources and chemical composition in view of the complex mix of both biogenic and anthropogenic emissions, based on measurements from a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) and ancillary instrumentation. <br><br> Background concentrations (i.e. outside urban plumes) observed from the ATR42 indicate a fairly polluted region during the time of the campaign, with average concentrations of carbon monoxide of 131 ppb, ozone of 32 ppb, and aerosol particle number concentration ( > 15 nm) of 735 cm-3 stp. Regarding submicron aerosol composition (considering non-refractory species and black carbon, BC), organic aerosol (OA) is the most abundant species contributing 53 %, followed by SO4 (27 %), NH4 (11 %), BC (6 %), NO3 (2 %) and minor contribution of Cl (< 0.5 %). Average background PM1 in the region was 5.9 μg m-3 stp. During measurements of urban pollution plumes, mainly focusing on the outflow of Abidjan, Accra and Lomé, pollutants are significantly enhanced (e.g. average concentration of CO of 176 ppb, and aerosol particle number concentration of 6500 cm-3 stp), as well as PM1 concentration (11.9 μg m-3 stp). <br><br> Two classes of organic aerosols were estimated based on C-ToF-AMS: particulate organic nitrates (pONs) and isoprene epoxydiols secondary organic aerosols (IEPOX-SOA). Both classes are usually associated with the formation of particulate matter through complex interactions of anthropogenic and biogenic sources. During DACCIWA, pONs have a fairly small contribution to OA (around 5 %) and are more associated with long-range transport from central Africa than local formation. Conversely, IEPOX-SOA provides a significant contribution to OA (around 24 and 28 % under background and in-plume conditions). Furthermore, the fractional contribution of IEPOX-SOA is largely unaffected by changes in the aerosol composition (particularly the SO4 concentration), which suggests that IEPOX-SOA concentration is mainly driven by pre-existing aerosol surface, instead of aerosol chemical properties. At times of large in-plume SO4 enhancements (above 5 μg m-3), the fractional contribution of IEPOX-SOA to OA increases above 50 %, suggesting only then a change in the IEPOX-SOA-controlling mechanism. It is important to note that IEPOX-SOA constitutes a lower limit to the contribution of biogenic OA, given that other processes (e.g. non-IEPOX isoprene, monoterpene SOA) are likely in the region. Given the significant contribution to aerosol concentration, it is crucial that such complex biogenic-anthropogenic interactions are taken into account in both present-day and future scenario models of this fast-changing, highly sensitive region."
"57196437027;57196441294;7201787800;7006377579;57195257572;21933618400;37089603000;22834248200;8581789300;55581504800;55581504800;57196442038;6701802669;","In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign",2017,"10.5194/acp-17-13049-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028723346&doi=10.5194%2facp-17-13049-2017&partnerID=40&md5=2eab27fffcc917855f5a36ea7bd70e22","During austral summer 2015, the Microphysics of Antarctic Clouds (MAC) field campaign collected unique and detailed airborne and ground-based in situ measurements of cloud and aerosol properties over coastal Antarctica and the Weddell Sea. This paper presents the first results from the experiment and discusses the key processes important in this region, which is critical to predicting future climate change. <br><br> The sampling was predominantly of stratus clouds, at temperatures between ĝ'20 and 0ĝ€°C. These clouds were dominated by supercooled liquid water droplets, which had a median concentration of 113ĝ€cmĝ'3 and an interquartile range of 86ĝ€cmĝ'3. Both cloud liquid water content and effective radius increased closer to cloud top. The cloud droplet effective radius increased from 4ĝ€±ĝ€2ĝ€μm near cloud base to 8ĝ€±ĝ€3ĝ€μm near cloud top. <br><br> Cloud ice particle concentrations were highly variable with the ice tending to occur in small, isolated patches. Below approximately 1000ĝ€m, glaciated cloud regions were more common at higher temperatures; however, the clouds were still predominantly liquid throughout. When ice was present at temperatures higher than ĝ'10ĝ€°C, secondary ice production most likely through the Hallett&ndash;Mossop mechanism led to ice concentrations 1 to 3 orders of magnitude higher than the number predicted by commonly used primary ice nucleation parameterisations. The drivers of the ice crystal variability are investigated. No clear dependence on the droplet size distribution was found. The source of first ice in the clouds remains uncertain but may include contributions from biogenic particles, blowing snow or other surface ice production mechanisms. <br><br> The concentration of large aerosols (diameters 0.5 to 1.6ĝ€μm) decreased with altitude and were depleted in air masses that originated over the Antarctic continent compared to those more heavily influenced by the Southern Ocean and sea ice regions. The dominant aerosol in the region was hygroscopic in nature, with the hygroscopicity parameter <i>°</i> having a median value for the campaign of 0.66 (interquartile range of 0.38). This is consistent with other remote marine locations that are dominated by sea salt/sulfate."
"56321122100;25624545600;7102128820;35331137500;","Improved rain rate and drop size retrievals from airborne Doppler radar",2017,"10.5194/acp-17-11567-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030479795&doi=10.5194%2facp-17-11567-2017&partnerID=40&md5=acceb14a2c92c48c350ce4f6d1a4c3ac","Satellite remote sensing of rain is important for quantifying the hydrological cycle, atmospheric energy budget, and cloud and precipitation processes; however, radar retrievals of rain rate are sensitive to assumptions about the raindrop size distribution. The upcoming EarthCARE satellite will feature a 94GHz Doppler radar alongside lidar and radiometer instruments, presenting opportunities for enhanced retrievals of the raindrop size distribution. We demonstrate the capability to retrieve rain rate as a function of drop size and drop number concentration from airborne 94GHz Doppler radar measurements using CAPTIVATE, the variational retrieval algorithm developed for EarthCARE. For a range of rain regimes observed during the Tropical Composition, Cloud and Climate Coupling field campaign, we explore the contributions of mean Doppler velocity and path-integrated attenuation (PIA) measurements to the retrieval of rain rate, and the retrievals are evaluated against independent measurements from an independent 9.6GHz Doppler radar. The retrieved drop number concentrations vary over 5 orders of magnitude between very light rain from melting ice and warm rain from liquid clouds. In light rain conditions mean Doppler velocity facilitates estimates of rain rate without PIA, suggesting the possibility of EarthCARE rain rate estimates over land; in moderate warm rain, drop number concentration can be retrieved without mean Doppler velocity, with possible applications to CloudSat. © Author(s) 2017."
"57190075226;6701606453;6602805147;7102329065;56192746700;6505932008;","Toward an algorithm for estimating latent heat release in warm rain systems",2016,"10.1175/JTECH-D-15-0205.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977159817&doi=10.1175%2fJTECH-D-15-0205.1&partnerID=40&md5=41c4a9abc35e13899bf65cde2b5d7e2e","This paper outlines an approach for estimating latent heating, surface rainfall rate, and liquid water path in warm rain from downward-viewing W-band radar observations using a Bayesian Monte Carlo algorithm. The algorithm utilizes observed vertical and path-integrated characteristics of precipitating liquid clouds to identify the most appropriate hydrometeor and latent heating structures in a large database of profiles generated using a cloud-resolving model. These characteristics are selected by applying multiple performance metrics to synthetic retrievals. Analysis of the retrievals suggests that a combination of cloud-top, rain-top, and maximum reflectivity heights; vertically integrated reflectivity and attenuation; and a measure of nearsurface intensity is sufficient to constrain bulk properties and the vertical structure of warm rain systems. When applied to observations at CloudSat resolution, biases in retrieved liquid water path and surface rainfall rate are small (less than 10%). The algorithm also captures the vertical structure of latent heating, although the magnitudes of integrated heating and cooling exhibit nearly compensating low biases. Random errors are larger owing to the limitations of single-frequency radar observations in constraining drop size distributions. Uncertainties in the altitudes of peak heating and cooling at the pixel scale are typically less than one vertical level, while uncertainties in vertically resolved estimates of heating and cooling rates are on the order of a factor of 2. The utility of the technique is illustrated through application to case studies from airborne radar data from the VAMOS Ocean-Cloud-Atmosphere-Land Study field campaign and satellite observations from CloudSat. © 2016 American Meteorological Society."
"55973913400;7006434689;55999273500;56442378900;35751142400;14034301300;56533839200;55554016600;6701842515;7005069415;","The Ice Selective Inlet: A novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds",2015,"10.5194/amt-8-3087-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84938635314&doi=10.5194%2famt-8-3087-2015&partnerID=40&md5=19e61d2e844854be5130b84fbd3fb9ef","Climate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosol-cloud interactions. One of the poorly understood processes is formation of mixed-phase clouds (MPCs) via heterogeneous ice nucleation. Field measurements of the atmospheric ice phase in MPCs are challenging due to the presence of much more numerous liquid droplets. The Ice Selective Inlet (ISI), presented in this paper, is a novel inlet designed to selectively sample pristine ice crystals in mixed-phase clouds and extract the ice residual particles contained within the crystals for physical and chemical characterization. Using a modular setup composed of a cyclone impactor, droplet evaporation unit and pumped counterflow virtual impactor (PCVI), the ISI segregates particles based on their inertia and phase, exclusively extracting small ice particles between 5 and 20 andmu;m in diameter. The setup also includes optical particle spectrometers for analysis of the number size distribution and shape of the sampled hydrometeors. The novelty of the ISI is a droplet evaporation unit, which separates liquid droplets and ice crystals in the airborne state, thus avoiding physical impaction of the hydrometeors and limiting potential artefacts. The design and validation of the droplet evaporation unit is based on modelling studies of droplet evaporation rates and computational fluid dynamics simulations of gas and particle flows through the unit. Prior to deployment in the field, an inter-comparison of the optical particle size spectrometers and a characterization of the transmission efficiency of the PCVI was conducted in the laboratory. The ISI was subsequently deployed during the Cloud and Aerosol Characterization Experiment (CLACE) 2013 and 2014-two extensive international field campaigns encompassing comprehensive measurements of cloud microphysics, as well as bulk aerosol, ice residual and ice nuclei properties. The campaigns provided an important opportunity for a proof of concept of the inlet design. In this work we present the setup of the ISI, including the modelling and laboratory characterization of its components, as well as field measurements demonstrating the ISI performance and validating the working principle of the inlet. Finally, measurements of biological aerosol during a Saharan dust event (SDE) are presented, showing a first indication of enrichment of bio-material in sub-2 μm ice residuals. © 2015 Author(s)."
"26632290800;57203209031;","MODIS comparisons with northeastern Pacific in situ stratocumulus microphysics",2015,"10.1002/2014JD022785","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942192537&doi=10.1002%2f2014JD022785&partnerID=40&md5=e9b29ccdfd1485233a0a2b3fcc051d70","Vertical sounding measurements within stratocumuli during two aircraft field campaigns, Marine Stratus/stratocumulus Experiment (MASE) and Physics of Stratocumulus Top (POST), are used to validate Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical thickness (COT), cloud liquid water path (LWP), and cloud effective radius (re). In situ COT, LWP, and re were calculated using 5m vertically averaged droplet probe measurements of complete vertical cloud penetrations. MODIS COT, LWP, and re 1 kmpixels were averaged along these penetrations. COT comparisons in POST showed strong correlations and a near 1: 1 relationship. In MASE, comparisons showed strong correlations; however, MODIS COT exceeded in situ COT, likely due to larger temporal differences between MODIS and in situmeasurements. LWP comparisons between two cloud probes show good agreement for POST but not MASE, giving confidence to POST data. Both projects provided strong LWP correlations but MODIS exceeded in situ by 14-36%. MODIS in situ re correlations were strong, but MODIS 2.1 µm re exceeded in situ re, which contributed to LWP bias; in POST, MODIS re was 20-30% greater than in situ re. Maximum in situ re near cloud top showed comparisons nearer 1: 1. Other MODIS re bands (3.7 µm and 1.6 µm) showed similar comparisons. Temporal differences between MODIS and in situ measurements, airplane speed differences, and cloud probe artifacts were likely causes of weaker MASE correlations. POST COT comparison was best for temporal differences under 20 min. POST data validate MODIS COT but it also implies a positive MODIS re bias that propagates to LWP while still capturing variability. © 2015. The Authors."
"6602999057;57204288222;","Introduction",2014,"10.1007/978-94-017-8978-3_1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84930888636&doi=10.1007%2f978-94-017-8978-3_1&partnerID=40&md5=67a124994784276572e042ab3ad07a90","Mineral dust is a key player in the Earth system with important impacts on the global energy and carbon cycles, acting on timescales of minutes to millennia. Megatons of dust are lifted each year into the atmosphere by strong near-surface winds over the world's arid regions. Such winds can be generated by short-lived small-scale dust devils, cold outflow from thunderstorms up to continental-scale dust storms. The tiny dust particles can be lifted to great heights and transported thousands of kilometres across the globe. Once airborne, dust affects radiation and clouds and thereby also precipitation. Dust also alters chemical processes in the atmosphere and deteriorates air quality and visibility for aviation. Dust is removed from the atmosphere by gravitational settling, turbulence or precipitation. Deposition on plants, snow and ice changes the amount of reflected solar radiation. Iron and other nutrients contained in dust fertilise both terrestrial and marine ecosystems. Dust deposits in glaciers, soils and ocean or lake sediments constitute an important archive of past environmental changes. For the first time, this book gives a detailed account of the state of the art in the fascinating, highly interdisciplinary and dynamically evolving area of dust research including results from field campaigns, laboratory, aircraft, satellite, modelling and theoretical studies. This chapter gives a short introduction into the topic, placing several recent developments in dust research into a historical context. © 2014 Springer Science+Business Media Dordrecht. All rights are reserved."
"36183122600;7005661275;56271306100;56271319700;6602633589;57197204963;37123320600;7004057920;","Observed influence of liquid cloud microphysical properties on ultraviolet surface radiation",2014,"10.1002/2013JD020309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896484245&doi=10.1002%2f2013JD020309&partnerID=40&md5=44ccd8e5733ccb7c04994c0bcda59ce7","Measurements of different UV quantities (UV index, ozone photolysis rates, global and diffuse irradiances, and actinic flux spectra) and cloud properties were collected during a field campaign carried out in Southern Italy in May–June 2010. Independent measurements of cloud liquid water path and optical depth allowed retrieving the cloud effective radius. The cloud modification factor (CMF) is used to investigate the influence of liquid cloud properties on the UV radiation under overcast conditions. CMF was also simulated using a 1-D radiative transfer model. Experimental and simulated CMF values for UV index (under overcast conditions) show a normalized root-mean-square error around 11%. Clouds with small effective radius determine a higher UV radiation attenuation than clouds formed by large particles. The CMFs for the UV index and the global spectral irradiance show a very weak dependence on the solar zenith angle (SZA), while the CMFs for actinic flux (both integrated and spectral) and diffuse spectral irradiance show a variation with SZA. The irradiance is more effectively attenuated at low SZA, while the actinic flux at high SZA. These effects are due to the different weight given to the direct and the diffuse components. © 2014. American Geophysical Union. All rights reserved."
"55262957100;7402469637;24451351900;15726586900;7103201242;7102609908;7102665424;55537009700;","The occurrence of cirrus clouds associated with eastward propagating equatorial n = 0 inertio-gravity and Kelvin waves in November 2011 during the CINDY2011/DYNAMO campaign",2013,"10.1002/2013JD019960","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84891274932&doi=10.1002%2f2013JD019960&partnerID=40&md5=2aaff7e563e4ab3219f537071db7804e","Cirrus cloud variability associated with n = 0 eastward inertio-gravity equatorial waves and equatorial Kelvin waves (both with the period of ~4 days) and equatorial Kelvin wave with another periodicity (~16 days) were observed in the tropical Indian Ocean (8.0°S, 80.5°E) in November of 2011 during the Cooperative Indian Ocean experiment on intraseasonal variability in the Year 2011 (CINDY2011)/Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign using balloon-borne cryogenic frostpoint hygrometers, Vaisala radiosondes, and a shipborne high spectral resolution lidar system. During early to mid-November, the cirrus cloud appearance corresponded primarily with high supersaturation and high relative humidity caused by the temperature disturbances associated with the ~4 day waves between 12 km altitude and the cold-point tropopause. The cirrus clouds disappeared under the unfavorable (downward wind and dry) conditions that were caused by the ~4 day waves, although the ~16 day wave was generating favorable conditions. Our multi-instrument cirrus measurements revealed that we must consider the phases of various overlapping waves when estimating dehydration efficiency caused by cirrus clouds around the cold-point tropopause. Key Points TTL cirrus clouds were observed over the tropical Indian Ocean Short-period equatorial waves affected the TTL cirrus clouds Wave overlapping is important for the dehydration ©2013. American Geophysical Union. All Rights Reserved."
"11839267100;7202772927;36867650000;7006432091;7004369046;57194974100;7006972903;7403577184;","A comparison of the water budgets between clouds from AMMA and TWP-ICE",2013,"10.1175/JAS-D-12-050.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874999403&doi=10.1175%2fJAS-D-12-050.1&partnerID=40&md5=2b4d9e938d08784622844a68ea49d0d2","Two field campaigns, the African Monsoon Multidisciplinary Analysis (AMMA) and the Tropical Warm Pool-International Cloud Experiment (TWP-ICE), took place in 2006 near Niamey, Niger, and Darwin, Northern Territory, Australia, providing extensive observations of mesoscale convective systems (MCSs) near a desert and a tropical coast, respectively. Under the constraint of their observations, three-dimensional cloud-resolving model simulations are carried out and presented in this paper to replicate the basic characteristics of the observed MCSs. All of the modeled MCSs exhibit a distinct structure having deep convective clouds accompanied by stratiform and anvil clouds. In contrast to the approximately 100-km-scale MCSs observed in TWP-ICE, the MCSs in AMMA have been successfully simulated with a scale of about 400 km. These modeled AMMA and TWP-ICE MCSs offer an opportunity to understand the structure and mechanism of MCSs. Comparing the water budgets between AMMA and TWP-ICE MCSs suggests that TWP-ICE convective clouds have stronger ascent while the mesoscale ascent outside convective clouds in AMMAis stronger.Acase comparison, with the aid of sensitivity experiments, also suggests that vertical wind shear and ice crystal (or dust aerosol) concentration can significantly impact stratiform and anvil clouds (e.g., their areas) in MCSs. In addition, the obtained water budgets quantitatively describe the transport of water between convective, stratiform, and anvil regions as well as water sources/sinks from microphysical processes, providing information that can be used to help determine parameters in the convective and cloud parameterizations in general circulation models (GCMs). © 2013 American Meteorological Society."
"7004741583;7006525200;7102074443;55946190800;9841756200;6604059069;8449668600;26426079600;16444950900;23476570200;6507506434;7003413606;6603662103;56257109300;8541571000;7006532784;7402548443;57203513475;7403386437;7004389827;7003796847;7005275497;6603916153;7004937718;7102511048;55450211100;57196488820;7003620360;35614095500;6603917221;37028325700;8426071600;7004095016;7006837187;16444006500;16444229300;6601922531;6603888503;6701564513;57217882217;55947921200;6603785227;10144282600;","An overview of the HIBISCUS campaign",2011,"10.5194/acp-11-2309-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79952691509&doi=10.5194%2facp-11-2309-2011&partnerID=40&md5=949e9b3db9e32714d86aa06136e3a40e","The EU HIBISCUS project consisted of a series of field campaigns during the intense convective summers in 2001, 2003 and 2004 in the State of São Paulo in Brazil. Its objective was to investigate the impact of deep convection on the Tropical Tropopause Layer (TTL) and the lower stratosphere by providing a new set of observational data on meteorology, tracers of horizontal and vertical transport, water vapour, clouds, and chemistry in the tropical Upper Troposphere/Lower Stratosphere (UT/LS). This was achieved using short duration research balloons to study local phenomena associated with convection over land, and long-duration balloons circumnavigating the globe to study the contrast between land and oceans. Analyses of observations of short-lived tracers, ozone and ice particles show strong episodic local updraughts of cold air across the lapse rate tropopause up to 18 or 19 km (420-440 K) in the lower stratosphere by overshooting towers. The long duration balloon and satellite measurements reveal a contrast between the composition of the lower stratosphere over land and oceanic areas, suggesting significant global impact of such events. The overshoots are shown to be well captured by non-hydrostatic meso-scale Cloud Resolving Models indicating vertical velocities of 50-60 ms-1 at the top of the Neutral Buoyancy Level (NBL) at around 14 km, but, in contrast, are poorly represented by global Chemistry-Transport Models (CTM) forced by Numerical Weather Forecast Models (NWP) underestimating the overshooting process. Finally, the data collected by the HIBISCUS balloons have allowed a thorough evaluation of temperature NWP analyses and reanalyses, as well as satellite ozone, nitrogen oxide, water vapour and bromine oxide measurements in the tropics. © 2011 Author(s)."
"23493863300;7201504886;","The echo size distribution of precipitating shallow cumuli",2010,"10.1175/2009JAS3178.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953336049&doi=10.1175%2f2009JAS3178.1&partnerID=40&md5=8752834544cf285fa2ba74067f02b562","S-band radar surveillance scans of precipitating shallow convection are analyzed. The scans are complied from 52 days of near-continuous measurements in the winter trades of the North Atlantic during the Rain in Cumulus over the Ocean (RICO) field campaign. After being analyzed and filtered to exclude spurious returns, the scans are segmented to identify contiguous returns, or echoes. The echo size and reflectivity statistics are then analyzed. A new normalization method is developed to account for biases associated with the nonuniformity in the native radar grid. The echo area distribution robustly exhibits power-law scaling up until sizes of about 10 km2, with a scaling exponent of about -1.1. At larger sizes the scaling behavior breaks down and varies more markedly across subsamples of the data. Conditional sampling suggests that the scaling behavior of the larger echoes does, however, approach that of the smaller echoes as echo coverage increases, which supports the idea of a limiting distribution. Departures from this limiting distribution are argued to reflect finite size effects, modulated by the presence of a capping inversion whose height and strength varies across the samples. © 2010 American Meteorological Society."
"6507731482;55017656900;25953950400;","Impact of aerosol intrusions on Arctic boundary layer clouds. Part II: Sea ice melting rates",2005,"10.1175/JAS3558.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-23744493105&doi=10.1175%2fJAS3558.1&partnerID=40&md5=4b454705e7c3f8443a71ac85189ddffa","The potential impact of intrusions of polluted air into the Arctic basin on sea ice melting rates and the surface energy budget is examined. This paper extends a previous study to cloud-resolving simulations of the entire spring season during the 1998 Surface Heat Budget of the Arctic (SHEBA) field campaign. For that purpose, the Los Alamos National Laboratory sea ice model is implemented into the research and real-time versions of the Regional Atmospheric Modeling System at Colorado State University (RAMSΓSU). This new version of RAMSΓSU also includes a new microphysical module that considers the explicit nucleation of cloud droplets and a bimodal representation of their spectrum. Different aerosol profiles based on 4 May 1998 observations were used to characterize the polluted upper layer and the 2-3 daily SHEBA soundings were utilized to provide time-evolving boundary conditions to the model. Results indicate that entrainment of ice-forming nuclei (IFN) from above the inversion increases the sea ice melting rates when mixed-phase clouds are present. An opposite although less important effect is associated with cloud condensation nuclei (CCN) entrainment when liquid-phase clouds prevail. © 2005 American Meteorological Society."
"6506020537;6701323933;7006689276;","Improvements of satellite-derived cyclonic rainfall over the North Atlantic",2003,"10.1175/1520-0442(2003)016<0657:IOSDCR>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038691812&doi=10.1175%2f1520-0442%282003%29016%3c0657%3aIOSDCR%3e2.0.CO%3b2&partnerID=40&md5=93515dba248d537e484ce144e919b04d","Case studies of rainfall, derived from Special Sensor Microwave Imager (SSM/I) satellite data during the passage of individual cyclones over the North Atlantic, are presented to enhance the knowledge of rainfall processes associated with frontal systems. A multisatellite method is applied for complete coverage of the North Atlantic twice a day. Different SSM/I precipitation algorithms have been tested for individual cyclones and compared to the Global Precipitation Climatology Project (GPCP) datasets. An independent rainfall pattern and intensity validation method is presented using voluntary observing ship (VOS) datasets and Advanced Very High Resolution Radiometer (AVHRR) images. Intense cyclones occur frequently in the wintertime period, with cold fronts propagating far south over the North Atlantic. Following upstream, large cloud clusters are frequently embedded in the cellular structured cold air of the backside regions, which produce heavy convective rainfall events, especially in the region off New-foundland around 50°N. These storms can be easily identified on AVHRR images. It transpired that only the SSM/I rainfall algorithm of Bauer and Schlüssel is sensitive enough to detect the rainfall patterns and intensities observed by VOS for those cyclone types over the North Atlantic. In contrast, the GPCP products do not recognize this backside rainfall, whereas the frontal rainfall conditions are well represented in all tested datasets. This is suggested from the results of an intensive intercomparison study with ship reports from the time period of the Fronts and Atlantic Storm Track Experiment (FASTEX) field campaign. For this purpose, a new technique has been developed to transfer ship report codes into rain-rate estimates. From the analysis of a complete life cycle of a cyclone, it follows that these mesoscale backside rainfall events contribute up to 25% to the total amount of rainfall in North Atlantic cyclones."
"7201826462;7005981420;","Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS: 3. Cloud Overlap",2000,"10.1029/1999JD901091","https://www.scopus.com/inward/record.uri?eid=2-s2.0-16644400824&doi=10.1029%2f1999JD901091&partnerID=40&md5=b5293a4e05cebfe634eb3d0d16746005","The vertical distribution of cloud layers has a significant effect on atmospheric radiative heating/cooling distributions. While multiple cloud layers are often observed to occur simultaneously by surface observers, satellite cloud retrieval methodology typically assumes that any individual imager pixel contains a single cloud layer. The purpose of this paper is to demonstrate a bispectral method that detects imager pixels containing possible cloud overlap when an optically thin cirrus cloud overlies a low-level water cloud, with at least a 2-km separation between layers. The method is developed from a scatterplot of the near-infrared 1.63-μm band reflectances and the 11-μm brightness temperatures using data from the MODIS (Moderate-Resolution Imaging Spectroradiometer) airborne simulator (MAS). The bispectral method is applied to a scene recorded by the MAS scanning spectrometer that was flown on the NASA ER-2 during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) field campaign during April and May 1996. For a scene recorded on April 21, 1996, at 2000 UTC, the complex vertical cloud structure was captured by lidar backscatter measurements from the Cloud Lidar System (CLS). The bispectral method appears to have a promising facility for identifying areas containing potential cloud overlap."
"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."
"7004068437;7408612236;","Linking boundary layer circulations and surface processes during FIFE 89. Part II: Maintenance of secondary circulation",1998,"10.1175/1520-0469(1998)055<1260:LBLCAS>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032052982&doi=10.1175%2f1520-0469%281998%29055%3c1260%3aLBLCAS%3e2.0.CO%3b2&partnerID=40&md5=1f912c56ff20603ee6c96bf5609298a6","Land-atmosphere interactions are examined for three different synoptic situations during a 21-day period in the course of the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment 1989 to better understand the relationship between biophysical feedback processes, boundary layer structure, and circulations in the boundary layer. The objective is to understand how the secondary circulation discussed in Part I of this paper was able to sustain itself throughout the duration of the 1989 intensive field campaign. The study is based on diagnostic analysis of measurements obtained from a network of surface meteorology and energy budget stations, augmented with high vertical resolution radiosonde measurements. Shallow convection associated with an undisturbed boundary layer situation and rainfall occurring during two different disturbed boundary layer situations - one associated with a surface trough, the other with the passage of a cold front - led to markedly different impacts on the surface layer and the boundary layer recovery timescale. In the undisturbed case, the growth of a cloud layer produced a negative feedback on the boundary layer by stabilizing the surface layer, and cutting off the turbulence transport of heat and moisture into the subcloud layer. The deficits in heat and moisture then led to cloud dissipation. During the surface trough development and cold front passage events, rainfall reaching the surface led to the collapse of the surface layer, decrease of surface and subsurface soil temperatures, depressed sensible heating, and a slow reduction and even temporary termination of evapotranspiration. After the rains subsided, the boundary layer recovery process began with vigorous evapotranspiration rates drying the upper soil layers on a timescale of 1-2 days. During this period, 55%-65% of the net surface available heating was used for evapotranspiration, whereas only 30%-35% went directly into boundary layer heating. As the near-surface soil moisture dropped, surface sensible heating became more important in influencing boundary layer energetics. The boundary layer required approximately two days to recover to its initial temperature in the case of the surface trough. After passage of the cold front, both the soil and boundary layer cooled and dried due to cold temperature advection. Evapotranspiration rates remained relatively large for about two days after the frontal passage. The boundary layer had not completely recovered by the end of the intensive data collection period after the frontal passage, so recovery time was at least a week. The analysis shows that with the exception of three days during the surface trough event, and two or three days during the frontal passage event, the surface-driven secondary circulation persisted."
"26634569400;9537045600;57202644034;8408994300;22980018800;36458602300;56638280100;57192869079;6506385754;6603768446;7005729142;7006575272;","The Microphysics of Stratiform Precipitation During OLYMPEX: Compatibility Between Triple-Frequency Radar and Airborne In Situ Observations",2019,"10.1029/2018JD029858","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067842078&doi=10.1029%2f2018JD029858&partnerID=40&md5=fdbc792b389489b16746888972730562","The link between stratiform precipitation microphysics and multifrequency radar observables is thoroughly investigated by exploiting simultaneous airborne radar and in situ observations collected from two aircraft during the OLYMPEX/RADEX (Olympic Mountain Experiment/Radar Definition Experiment 2015) field campaign. Above the melting level, in situ images and triple-frequency radar signatures both indicate the presence of moderately rimed aggregates. Various mass-size relationships of ice particles and snow scattering databases are used to compute the radar reflectivity from the in situ particle size distribution. At Ku and Ka band, the best agreement with radar observations is found when using the self-similar Rayleigh-Gans approximation for moderately rimed aggregates. At W band, a direct comparison is challenging because of the non-Rayleigh effects and of the probable attenuation due to ice aggregates and supercooled liquid water between the two aircraft. A variational method enables the retrieval of the full precipitation profile above and below the melting layer, by combining the observations from the three radars. Even with three radar frequencies, the retrieval of rain properties is challenging over land, where the integrated attenuation is not available. Otherwise, retrieved mean volume diameters and water contents of both solid and liquid precipitation are in agreement with in situ observations and indicate local changes of the degree of riming of ice aggregates, on the scale of 5 km. Finally, retrieval results are analyzed to explore the validity of using continuity constraints on the water mass flux and diameter within the melting layer in order to improve retrievals of ice properties. © 2019. The Authors"
"57191430389;57195361786;56210720700;7004885872;35340122000;7101846027;16308514000;","Aerosol characteristics in the entrainment interface layer in relation to the marine boundary layer and free troposphere",2018,"10.5194/acp-18-1495-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041423792&doi=10.5194%2facp-18-1495-2018&partnerID=40&md5=94b0d997b2b2ba94e63d54dd644029e5","This study uses airborne data from two field campaigns off the California coast to characterize aerosol size distribution characteristics in the entrainment interface layer (EIL), a thin and turbulent layer above marine stratocumulus cloud tops, which separates the stratocumulus-topped boundary layer (STBL) from the free troposphere (FT). The vertical bounds of the EIL are defined in this work based on considerations of buoyancy and turbulence using thermodynamic and dynamic data. Aerosol number concentrations are examined from three different probes with varying particle diameter (<i>D</i>p) ranges: &gt;ĝ€̄3ĝ€̄nm, &gt;ĝ€̄10ĝ€̄nm, and 0.11-3.4ĝ€̄μm. Relative to the EIL and FT layers, the sub-cloud (SUB) layer exhibited lower aerosol number concentrations and higher surface area concentrations. High particle number concentrations between 3 and 10ĝ€̄nm in the EIL are indicative of enhanced nucleation, assisted by high actinic fluxes, cool and moist air, and much lower surface area concentrations than the STBL. Slopes of number concentration versus altitude in the EIL were correlated with the particle number concentration difference between the SUB and lower FT layers. The EIL aerosol size distribution was influenced by varying degrees from STBL aerosol versus subsiding FT aerosol depending on the case examined. These results emphasize the important role of the EIL in influencing nucleation and aerosol-cloud-climate interactions. © Author(s) 2018."
"35206636900;7003729315;7004166136;7202016984;55087038900;","The impact of lidar detection sensitivity on assessing aerosol direct radiative effects",2017,"10.1002/2017GL074521","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029006230&doi=10.1002%2f2017GL074521&partnerID=40&md5=c71fabf15e3ed02cb61879bb30154818","Spaceborne lidar observations have great potential to provide accurate global estimates of the aerosol direct radiative effect (DRE) in both clear and cloudy conditions. However, comparisons between observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO) and multiple years of Atmospheric Radiation Measurement (ARM) program's ground-based Raman lidars (RL) show that CALIPSO does not detect all radiatively significant aerosol, i.e., aerosol that directly modifies the Earth's radiation budget. We estimated that using CALIPSO observations results in an underestimate of the magnitude of the global mean aerosol DRE by up to 54%. The ARM RL data sets along with NASA Langley airborne high spectral resolution lidar data from multiple field campaigns are used to derive the detection sensitivity required to accurately resolve the aerosol DRE. This shows that a lidar with a backscatter coefficient detection sensitivity of about 1–2 × 10−4 km−1 sr−1 at 532 nm would resolve all the aerosol needed to derive the DRE to within 1%. ©2017. American Geophysical Union. All Rights Reserved. This article has been contributed to by US Government employees and their work is in the public domain in the USA."
"56771426500;6603868770;6603196991;16480992300;7004881313;","Ground-based lidar and microwave radiometry synergy for high vertical resolution absolute humidity profiling",2016,"10.5194/amt-9-4013-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984848216&doi=10.5194%2famt-9-4013-2016&partnerID=40&md5=1f99f0df96e799a4ebfa7f32c55479a5","Continuous monitoring of atmospheric humidity profiles is important for many applications, e.g., assessment of atmospheric stability and cloud formation. Nowadays there are a wide variety of ground-based sensors for atmospheric humidity profiling. Unfortunately there is no single instrument able to provide a measurement with complete vertical coverage, high vertical and temporal resolution and good performance under all weather conditions, simultaneously. For example, Raman lidar (RL) measurements can provide water vapor with a high vertical resolution, albeit with limited vertical coverage, due to sunlight contamination and the presence of clouds. Microwave radiometers (MWRs) receive water vapor information throughout the troposphere, though their vertical resolution is poor. In this work, we present an MWR and RL system synergy, which aims to overcome the specific sensor limitations. The retrieval algorithm combining these two instruments is an optimal estimation method (OEM), which allows for an uncertainty analysis of the retrieved profiles. The OEM combines measurements and a priori information, taking the uncertainty of both into account. The measurement vector consists of a set of MWR brightness temperatures and RL water vapor profiles. The method is applied to a 2-month field campaign around Jülich (Germany), focusing on clear sky periods. Different experiments are performed to analyze the improvements achieved via the synergy compared to the individual retrievals. When applying the combined retrieval, on average the theoretically determined absolute humidity uncertainty is reduced above the last usable lidar range by a factor of ĝ1/4 ĝ€2 with respect to the case where only RL measurements are used. The analysis in terms of degrees of freedom per signal reveal that most information is gained above the usable lidar range, especially important during daytime when the lidar vertical coverage is limited. The retrieved profiles are further evaluated using radiosounding and Global Position Satellite (GPS) water vapor measurements. In general, the benefit of the sensor combination is especially strong in regions where Raman lidar data are not available (i.e., blind regions, regions characterized by low signal-to-noise ratio), whereas if both instruments are available, RL dominates the retrieval. In the future, the method will be extended to cloudy conditions, when the impact of the MWR becomes stronger. © Author(s) 2016. CC Attribution 3.0 License."
"56091546800;55625385200;56091652300;56091668400;12645700600;6602137606;7004934146;","Microphysics and energy and water fluxes of various fog types at SIRTA, France",2015,"10.1016/j.atmosres.2014.03.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910035616&doi=10.1016%2fj.atmosres.2014.03.016&partnerID=40&md5=dcedb600e0537c06a959b6dcdb1a581e","During the PARISFOG campaign in winter 2012/2013, microphysical properties and turbulent fluxes of fog droplets (liquid water), water vapor, and energy were characterized and quantified during fog events of various types that occurred at the SIRTA (Site Instrumental de Recherche par Télédétection Atmosphérique) atmospheric observatory outside Paris. The eddy covariance technique was applied, employing a fast (10. Hz) fog droplet spectrometer, a three-dimensional ultrasonic anemometer, and a fast response gas analyzer, which were operated at an altitude of 2.5. m above ground. A visibility meter was used to detect the occurrence and density of fog. A total of twenty-one fog events were measured during the field campaign. After applying quality criteria, six events remained. For this study, two fog events out of the six, representing a radiation fog and stratus lowering fog, respectively, are analyzed in detail. The two fog events exhibited very distinct patterns in terms of fog droplet size distribution, fog number concentration, and liquid water content. The evolution of these microphysical properties is elucidated through combined analysis of the turbulent fluxes of fog droplets (liquid water), water vapor and energy as well as reasoning of microphysical processes like, condensation, collision-coalescence, and droplet evaporation. Downward droplet number fluxes and liquid water fluxes were mostly observed in stratus lowering fog, however, upward fluxes were also observed in response to downward water vapor fluxes. In radiation fog, both upward and downward droplet number fluxes and liquid water fluxes were observed depending on the position at which the microphysical process was observed with respect to the measurement height. Bi-directional fog droplet fluxes with different flux directions of smaller and larger droplets were observed. In both fog events, the downward water vapor fluxes were the major cause for (I) the broadening of the fog droplet size distribution and (II) the largest upward fog water fluxes throughout the whole event. © 2014 Elsevier B.V."
"56212055700;24776869700;35621058500;56237539400;","Comparison of IASI water vapor retrieval with H2O-Raman lidar in the framework of the Mediterranean HyMeX and ChArMEx programs",2014,"10.5194/acp-14-9583-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907203421&doi=10.5194%2facp-14-9583-2014&partnerID=40&md5=44388f9c9b3b5c63d07f799044390d33","The Infrared Atmospheric Sounding Interferometer (IASI) is a new generation spaceborne passive sensor mainly dedicated to meteorological applications. Operational Level-2 products have been available via the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) for several years. In particular, vertical profiles of water vapor measurements are retrieved from infrared radiances at the global scale. Nevertheless, the robustness of such products has to be checked because only a few validations have been reported. For this purpose, the field experiments that were held during the HyMeX and ChArMEx international programs are a very good opportunity. A H2O-Raman lidar was deployed on the Balearic island of Menorca and operated continuously for ∼ 6 and ∼ 3 weeks during fall 2012 (Hydrological cycle in the Mediterranean eXperiment-HyMeX) and summer 2013 (Chemistry-Aerosol Mediterranean Experiment-ChArMEx), respectively. It measured simultaneously the water vapor mixing ratio and aerosol optical properties. This article does not aim to describe the IASI operational H2O inversion algorithm, but to compare the vertical profiles derived from IASI onboard (meteorological operational) MetOp-A and the ground-based lidar measurements to assess the reliability of the IASI operational product for the water vapor retrieval in both the lower and middle troposphere. The links between water vapor contents and both the aerosol vertical profiles and the air mass origins are also studied. About 30 simultaneous observations, performed during nighttime in cloud free conditions, have been considered. For altitudes ranging from 2 to 7 km, root mean square errors (correlation) of ∼ 0.5 g kgg'1 (∼ 0.77) and ∼ 1.1 g kgg'1 (∼ 0.72) are derived between the operational IASI product and the available lidar profiles during HyMeX and ChArMEx, respectively. The values of both root mean square error and correlation are meaningful and show that the operational Level-2 product of the IASI-derived vertical water vapor mixing ratio can be considered for meteorological and climatic applications, at least in the framework of field campaigns. © 2014 Author(s)."
"55463274000;23065650200;7402934750;55663817800;","Parameterization of ice fall speeds in midlatitude cirrus: Results from SPartICus",2014,"10.1002/2013JD020602","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84938216440&doi=10.1002%2f2013JD020602&partnerID=40&md5=7ef0460b16d957a854a372330b1739f3","The climate sensitivity predicted in general circulation models can be sensitive to the treatment of the ice particle fall velocity. In this study, the mass-weighted ice fall speed (Vm) and the number concentration ice fall speed (Vn) in midlatitude cirrus clouds are computed from in situ measurements of ice particle area and number concentration made by the two-dimensional stereo probe during the Small Particles In Cirrus field campaign. For single-moment ice microphysical schemes, Vm and the ice particle size distribution effective diameter De were parameterized in terms of cloud temperature (T) and ice water content (IWC). For two-moment schemes, Vm and Vn were related to De and the mean maximum dimension ‾D, respectively. For single-moment schemes, although the correlations of Vm and De with T were higher than the correlations of Vm and De with IWC, it is demonstrated that Vm and De are better predicted by using both T and IWC. The parameterization relating Vm to T and IWC is compared with another scheme relating Vm to T and IWC, with the latter based on millimeter cloud radar measurements. Regarding two-moment ice microphysical schemes, a strong correlation was found between De and Vm and between ‾D and Vn owing to their similar weightings by ice particle mass and number concentration, respectively. Estimating Vm from De makes Vm a function of IWC and projected area, realistically coupling Vm with both the cloud microphysics and radiative properties. © 2014. American Geophysical Union. All Rights Reserved."
"7003582587;24764483400;55746931700;6506545080;7006698304;25823927100;7401936984;35917252100;","Evaluation of intercomparisons of four different types of model simulating TWP-ICE",2014,"10.1002/qj.2192","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84899493580&doi=10.1002%2fqj.2192&partnerID=40&md5=b97f4efcee23c0a3e371ca0e5e2c04e4","Four model intercomparisons were run and evaluated using the TWP-ICE field campaign, each involving different types of atmospheric model. Here we highlight what can be learnt from having single-column model (SCM), cloud-resolving model (CRM), global atmosphere model (GAM) and limited-area model (LAM) intercomparisons all based around the same field campaign. We also make recommendations for anyone planning further large multi-model intercomparisons to ensure they are of maximum value to the model development community. CRMs tended to match observations better than other model types, although there were exceptions such as outgoing long-wave radiation. All SCMs grew large temperature and moisture biases and performed worse than other model types for many diagnostics. The GAMs produced a delayed and significantly reduced peak in domain-average rain rate when compared to the observations. While it was shown that this was in part due to the analysis used to drive these models, the LAMs were also driven by this analysis and did not have the problem to the same extent. Based on differences between the models with parametrized convection (SCMs and GAMs) and those without (CRMs and LAMs), we speculate that that having explicit convection helps to constrain liquid water whereas the ice contents are controlled more by the representation of the microphysics. © 2013 Royal Meteorological Society and Crown Copyright, the Met Office. Quarterly Journal of the Royal Meteorological Society © 2013 Royal Meteorological Society."
"11440653000;6506191803;6701530776;6603137309;","Cloud streets and land-water interactions in the Amazon",2011,"10.1007/s10533-011-9580-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052271970&doi=10.1007%2fs10533-011-9580-4&partnerID=40&md5=1fe55fca89455f2f26937a18b157fedc","Cloud streets are common feature in the Amazon Basin. They form from the combination of the vertical trade wind stress and moist convection. Here, satellite imagery, data collected during the COBRA-PARÁ (Caxiuanã Observations in the Biosphere, River and Atmosphere of Pará) field campaign, and high resolution modeling are used to understand the streets′ formation and behavior. The observations show that the streets have an aspect ratio of about 3. 5 and they reach their maximum activity around 15:00 UTC when the wind shear is weaker, and the convective boundary layer reaches its maximum height. The simulations reveal that the cloud streets onset is caused by the local circulations and convection produced at the interfaces between forest and rivers of the Amazon. The satellite data and modeling show that the large rivers anchor the cloud streets producing a quasi-stationary horizontal pattern. The streets are associated with horizontal roll vortices parallel to the mean flow that organizes the turbulence causing advection of latent heat flux towards the upward branches. The streets have multiple warm plumes that promote a connection between the rolls. These spatial patterns allow fundamental insights on the interpretation of the Amazon exchanges between surface and atmosphere with important consequences for the climate change understanding. © 2011 Springer Science+Business Media B.V."
"7501447027;7003283811;7005802462;7006791463;36712188700;22036874400;38461550200;","Development of the NASA high-altitude imaging wind and rain airborne profiler",2011,"10.1109/AERO.2011.5747415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955771137&doi=10.1109%2fAERO.2011.5747415&partnerID=40&md5=4f5b03d8b4551a80fa1a6141766572e2","The scope of this paper is the development and recent field deployments of the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), which was funded under the NASA Instrument Incubator Program (IIP) [1]. HIWRAP is a dual-frequency (Ka- and Ku-band), dual-beam (30° and 40° incidence angles), conical scanning, Doppler radar system designed for operation on the NASA high-altitude (65,000 ft) Global Hawk Unmanned Aerial System (UAS). It utilizes solid state transmitters along with a novel pulse compression scheme that results in a system with compact size, light weight, less power consumption, and low cost compared to radars currently in use for precipitation and Doppler wind measurements. By combining measurements at Ku- and Ka-band, HIWRAP is able to image winds through measuring volume backscattering from clouds and precipitation. In addition, HIWRAP is also capable of measuring surface winds in an approach similar to SeaWinds on QuikScat. To this end, HIWRAP hardware and software development has been completed. It was installed on the NASA WB57 for instrument test flights in March, 2010 and then deployed on the NASA Global Hawk for supporting the Genesis and Rapid Intensification Processes (GRIP) field campaign in August-September, 2010. This paper describes the scientific motivations of the development of HIWRAP as well as system hardware, aircraft integration and flight missions. Preliminary data from GRIP science flights is also presented. © 2011 IEEE."
"7201646465;55476510600;56853406500;","Sensitivity of simulated mesoscale atmospheric circulations resulting from landscape heterogeneity to aspects of model configuration",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448933171&partnerID=40&md5=3f8a4f6d8a14b7fb471495261253d666","Recent work has demonstrated the importance of anthropogenic landscape heterogeneity in Amazonia and the central U.S. in forcing mesoscale atmospheric circulations and generating clouds and precipitation. It has been shown that failing to account for this surface heterogeneity may have important implications for the simulation of land-atmosphere interactions in large-scale atmospheric models. The work presented here shows that, in addition to correctly specifying the surface forcing, accurate simulation of landscape-induced mesoscale effects with a regional model (e.g., Regional Atmospheric Modeling System, RAMS) depends critically on informed choices of aspects of model configuration. These include horizontal resolution, strength of nudging, and atmospheric initialization. Sensitivity experiments designed to illustrate the impact of varying these factors on RAMS-simulated, landscape-induced mesoscale circulations are presented here. These results, supported by dynamical and scaling arguments, suggest that model configuration can have at least as great an impact on the simulated mesoscale circulations, fluxes, and PBL structure as correctly accounting for mesoscale landscape heterogeneity. Such experiments therefore provide crucial guidance for optimally constructing simulations of mesoscale land-atmosphere interaction important for a variety of applications from field campaigns to parameterization development. Copyright 2002 by the American Geophysical Union."
"37056101400;6602080205;57192172364;7003615192;57201027251;15926468600;","Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara",2019,"10.5194/acp-19-15353-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072107852&doi=10.5194%2facp-19-15353-2019&partnerID=40&md5=78f476bba793c14fc7830598f2c7aa29","Mineral dust is an important component of the climate system, interacting with radiation, clouds, and biogeochemical systems and impacting atmospheric circulation, air quality, aviation, and solar energy generation. These impacts are sensitive to dust particle size distribution (PSD), yet models struggle or even fail to represent coarse (diameter (d) > 2:5 μm) and giant (d > 20 μm) dust particles and the evolution of the PSD with transport. Here we examine three state-of-the-art airborne observational datasets, all of which measured the full size range of dust (d D 0:1 to > 100 μm) at different stages during transport with consistent instrumentation. We quantify the presence and evolution of coarse and giant particles and their contribution to optical properties using airborne observations over the Sahara (from the Fennec field campaign) and in the Saharan Air Layer (SAL) over the tropical eastern Atlantic (from the AER-D field campaign). Observations show significantly more abundant coarse and giant dust particles over the Sahara compared to the SAL: effective diameters of up to 20 μm were observed over the Sahara compared to 4 μm in the SAL. Excluding giant particles over the Sahara results in significant underestimation of mass concentration (40 %), as well as underestimates of both shortwave and longwave extinction (18% and 26 %, respectively, from scattering calculations), while the effects in the SAL are smaller but non-negligible. The larger impact on longwave extinction compared to shortwave implies a bias towards a radiative cooling effect in dust models, which typically exclude giant particles and underestimate coarse-mode concentrations. A compilation of the new and published effective diameters against dust age since uplift time suggests that two regimes of dust transport exist. During the initial 1.5 d, both coarse and giant particles are rapidly deposited. During the subsequent 1.5 to 10 d, PSD barely changes with transport, and the coarse mode is retained to a much greater degree than expected from estimates of gravitational sedimentation alone. The reasons for this are unclear and warrant further investigation in order to improve dust transport schemes and the associated radiative effects of coarse and giant particles in models. © 2019 Copernicus GmbH. All rights reserved."
"55927053800;7202154370;55752760600;8724962900;56065138100;55990594100;57201737970;7006151934;7401793588;57208765879;7102805852;","Observation of absorbing aerosols above clouds over the south-east Atlantic Ocean from the geostationary satellite SEVIRI-Part 1: Method description and sensitivity",2019,"10.5194/acp-19-9595-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070098079&doi=10.5194%2facp-19-9595-2019&partnerID=40&md5=64b754468abd473b6eeef2d3250d48a3","High-temporal-resolution observations from satellites have a great potential for studying the impact of biomass burning aerosols and clouds over the south-east Atlantic Ocean (SEAO). This paper presents a method developed to simultaneously retrieve aerosol and cloud properties in aerosol above-cloud conditions from the geostationary instrument Meteosat Second Generation/Spinning Enhanced Visible and Infrared Imager (MSG/SEVIRI). The above-cloud aerosol optical thickness (AOT), the cloud optical thickness (COT) and the cloud droplet effective radius (CER) are derived from the spectral contrast and the magnitude of the signal measured in three channels in the visible to shortwave infrared region. The impact of the absorption from atmospheric gases on the satellite signal is corrected by applying transmittances calculated using the water vapour profiles from a Met Office forecast model. The sensitivity analysis shows that a 10 % error on the humidity profile leads to an 18.5 % bias on the above-cloud AOT, which highlights the importance of an accurate atmospheric correction scheme. In situ measurements from the CLARIFY-2017 airborne field campaign are used to constrain the aerosol size distribution and refractive index that is assumed for the aforementioned retrieval algorithm. The sensitivities in the retrieved AOT, COT and CER to the aerosol model assumptions are assessed. Between 09:00 and 15:00 UTC, an uncertainty of 40 % is estimated on the above-cloud AOT, which is dominated by the sensitivity of the retrieval to the single-scattering albedo. The absorption AOT is less sensitive to the aerosol assumptions with an uncertainty generally lower than 17 % between 09:00 and 15:00 UTC. Outside of that time range, as the scattering angle decreases, the sensitivity of the AOT and the absorption AOT to the aerosol model increases. The retrieved cloud properties are only weakly sensitive to the aerosol model assumptions throughout the day, with biases lower than 6 % on the COT and 3 % on the CER. The stability of the retrieval over time is analysed. For observations outside of the backscattering glory region, the time series of the aerosol and cloud properties are physically consistent, which confirms the ability of the retrieval to monitor the temporal evolution of aerosol above-cloud events over the SEAO. © 2019 Author(s)."
"55554574300;55879760100;35551238800;55683878900;56495287900;6603089578;56522444900;6602810042;7003510880;6602999057;8571030900;26665602100;57195673296;57218243091;24448387100;55532508600;6507896695;","Diurnal cycle of coastal anthropogenic pollutant transport over southern West Africa during the DACCIWA campaign",2019,"10.5194/acp-19-473-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060048660&doi=10.5194%2facp-19-473-2019&partnerID=40&md5=692ee89e469b9ebbc8ea9eeb8fcca7c3","During the monsoon season, pollutants emitted by large coastal cities and biomass burning plumes originating from central Africa have complex transport pathways over southern West Africa (SWA). The Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) field campaign has provided numerous dynamical and chemical measurements in and around the super-site of Savè in Benin (≈ 185km away from the coast), which allows quantification of the relative contribution of advected pollutants. Through the combination of in situ ground measurements with aircraft, radio-sounding, satellite, and high-resolution chemistry-transport modeling with the CHIMERE model, the source attribution and transport pathways of pollutants inland (here, NOx and CO) are carefully analyzed for the 1-7 July 2016 period. The relative contributions of different sources (i.e., emissions from several large coastal cities) to the air quality in Savè are characterized. It is shown that a systematic diurnal cycle exists with high surface concentrations of pollutants from 18:00 to 22:00UTC. This evening peak is attributed to pollution transport from the coastal city of Cotonou (Benin). Numerical model experiments indicate that the anthropogenic pollutants are accumulated during the day close to the coast and transported northward as soon as the daytime convection in the atmospheric boundary layer ceases after 16:00UTC, reaching 8°N at 21:00UTC. When significant biomass burning pollutants are transported into continental SWA, they are mixed with anthropogenic pollutants along the coast during the day, and this mixture is then transported northward. At night, most of the coastal anthropogenic plumes are transported within the planetary boundary layer (below about 500m above ground level), whereas the biomass burning pollutants are mostly transported above it, thus generally not impacting ground level air quality. © 2019 Copernicus GmbH. All rights reserved."
"40461229800;42361350100;7006041988;14035836100;6603293519;7404544551;","The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska",2018,"10.5194/acp-18-555-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040724107&doi=10.5194%2facp-18-555-2018&partnerID=40&md5=07707b4fcd6c25229dfdcbc590161f0b","The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM) program's Fifth Airborne Carbon Measurements (ACME-V) field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission. © Author(s) 2018."
"57195327788;42062523800;7003926380;7003535385;12800966700;8657166100;7101638860;6701754792;","A ubiquitous ice size bias in simulations of tropical deep convection",2017,"10.5194/acp-17-9599-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027151353&doi=10.5194%2facp-17-9599-2017&partnerID=40&md5=139c21d6f2396a4579ccba7100be0ad4","The High Altitude Ice Crystals - High Ice Water Content (HAIC-HIWC) joint field campaign produced aircraft retrievals of total condensed water content (TWC), hydrometeor particle size distributions (PSDs), and vertical velocity (w) in high ice water content regions of mature and decaying tropical mesoscale convective systems (MCSs). The resulting dataset is used here to explore causes of the commonly documented high bias in radar reflectivity within cloud-resolving simulations of deep convection. This bias has been linked to overly strong simulated convective updrafts lofting excessive condensate mass but is also modulated by parameterizations of hydrometeor size distributions, single particle properties, species separation, and microphysical processes. Observations are compared with three Weather Research and Forecasting model simulations of an observed MCS using different microphysics parameterizations while controlling for w, TWC, and temperature. Two popular bulk microphysics schemes (Thompson and Morrison) and one bin microphysics scheme (fast spectral bin microphysics) are compared. For temperatures between -10 and -40 °C and TWC &gt; 1 g m-3, all microphysics schemes produce median mass diameters (MMDs) that are generally larger than observed, and the precipitating ice species that controls this size bias varies by scheme, temperature, and w. Despite a much greater number of samples, all simulations fail to reproduce observed high-TWC conditions (&gt; 2 g m-3) between -20 and -40 °C in which only a small fraction of condensate mass is found in relatively large particle sizes greater than 1 mm in diameter. Although more mass is distributed to large particle sizes relative to those observed across all schemes when controlling for temperature, w, and TWC, differences with observations are significantly variable between the schemes tested. As a result, this bias is hypothesized to partly result from errors in parameterized hydrometeor PSD and single particle properties, but because it is present in all schemes, it may also partly result from errors in parameterized microphysical processes present in all schemes. Because of these ubiquitous ice size biases, the frequently used microphysical parameterizations evaluated in this study inherently produce a high bias in convective reflectivity for a wide range of temperatures, vertical velocities, and TWCs. © 2017 Author(s)."
"57190728339;7003606341;57210010133;","Effects of wind shear and radiative cooling on the stratocumulus-topped boundary layer",2016,"10.1002/qj.2903","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996480128&doi=10.1002%2fqj.2903&partnerID=40&md5=576eceea8c3aca8c56a68369accdbeaf","The effects of wind shear and radiative cooling on the stratocumulus-topped boundary layer (STBL) were investigated via a set of large-eddy simulations. The set-up of the numerical experiments was based on Flight TO13 from the Physics of Stratocumulus Top (POST) field campaign, in which sensible and latent heat fluxes at the surface were small and thermodynamic conditions prevented cloud-top entrainment instability. The results demonstrate that the presence of radiative cooling invigorated convective circulations across the STBL and sharpened the inversion above the cloud, while wind shear at the top of the STBL was a source of turbulence in the capping inversion and caused dilution of the cloud top. The flux and gradient Richardson numbers in the capping inversion and in the topmost layer of the cloud were nearly critical. Analysis of the turbulent kinetic energy (TKE) budget and its transport indicated that turbulence in the inversion capping the cloud was produced locally by wind shear and was dynamically decoupled from the turbulence driven by convective circulations across the STBL. Similar conclusions were derived for the topmost part of the cloud. © 2016 Royal Meteorological Society"
"55683061800;35473805400;16308514000;7005035762;7101846027;","Precipitation susceptibility in marine stratocumulus and shallow cumulus from airborne measurements",2016,"10.5194/acp-16-11395-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988346161&doi=10.5194%2facp-16-11395-2016&partnerID=40&md5=086cbf633a4a9575353082a153be2d9c","Precipitation tends to decrease as aerosol concentration increases in warm marine boundary layer clouds at fixed liquid water path (LWP). The quantitative nature of this relationship is captured using the precipitation susceptibility (<i>S</i><i>o</i>) metric. Previously published works disagree on the qualitative behavior of <i>S</i><i>o</i> in marine low clouds: <i>S</i><i>o</i> decreases monotonically with increasing LWP or cloud depth (<i>H</i>) in stratocumulus clouds (Sc), while it increases and then decreases in shallow cumulus clouds (Cu). This study uses airborne measurements from four field campaigns on Cu and Sc with similar instrument packages and flight maneuvers to examine if and why <i>S</i><i>o</i> behavior varies as a function of cloud type. The findings show that <i>S</i><i>o</i> increases with <i>H</i> and then decreases in both Sc and Cu. Possible reasons for why these results differ from those in previous studies of Sc are discussed. © Author(s) 2016."
"55683061800;35473805400;7003591311;7101846027;7004885872;39761266700;","Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment-Part 1: Distributions and variability",2016,"10.5194/acp-16-8643-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978757665&doi=10.5194%2facp-16-8643-2016&partnerID=40&md5=fc121b9837bf5d6da6b0f287518f8211","Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment-BACEX, March-April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics. The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 μm (diameter), particles that are large enough to be effective giant cloud condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer), Africa (Saharan air layer), and midlatitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period. The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ∼3 km, while most clouds were less than 1 km deep. Clouds tend to precipitate when the cloud is thicker than 500-600 m. Distributions of cloud field characteristics (depth, radar reflectivity, Doppler velocity, precipitation) were well identified in the reflectivity-velocity diagram from the cloud radar observations. Two types of precipitation features were observed for shallow marine cumulus clouds that may impact boundary layer differently: first, a classic cloud-base precipitation where precipitation shafts were observed to emanate from the cloud base; second, cloud-top precipitation where precipitation shafts emanated mainly near the cloud tops, sometimes accompanied by precipitation near the cloud base. The second type of precipitation was more frequently observed during the experiment. Only 42-44% of the clouds sampled were non-precipitating throughout the entire cloud layer and the rest of the clouds showed precipitation somewhere in the cloud, predominantly closer to the cloud top. © 2016 Author(s)."
"56976200200;9043417100;57189089842;7006377579;7201787800;57195257572;7103016965;35740180800;7006235542;","Comparing model and measured ice crystal concentrations in orographic clouds during the INUPIAQ campaign",2016,"10.5194/acp-16-4945-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966340251&doi=10.5194%2facp-16-4945-2016&partnerID=40&md5=e014adb982dbcf134d538ee705afa0ba","This paper assesses the reasons for high ice number concentrations observed in orographic clouds by comparing in situ measurements from the Ice NUcleation Process Investigation And Quantification field campaign (INUPIAQ) at Jungfraujoch, Switzerland (3570ma.s.l.) with the Weather Research and Forecasting model (WRF) simulations over real terrain surrounding Jungfraujoch. During the 2014 winter field campaign, between 20 January and 28 February, the model simulations regularly underpredicted the observed ice number concentration by 103L-1. Previous literature has proposed several processes for the high ice number concentrations in orographic clouds, including an increased ice nucleating particle (INP) concentration, secondary ice multiplication and the advection of surface ice crystals into orographic clouds. We find that increasing INP concentrations in the model prevents the simulation of the mixed-phase clouds that were witnessed during the INUPIAQ campaign at Jungfraujoch. Additionally, the inclusion of secondary ice production upwind of Jungfraujoch into the WRF simulations cannot consistently produce enough ice splinters to match the observed concentrations. A flux of surface hoar crystals was included in the WRF model, which simulated ice concentrations comparable to the measured ice number concentrations, without depleting the liquid water content (LWC) simulated in the model. Our simulations therefore suggest that high ice concentrations observed in mixed-phase clouds at Jungfraujoch are caused by a flux of surface hoar crystals into the orographic clouds. © Author(s) 2016."
"54403961000;24468389200;15830929400;","Impacts of cloud overlap assumptions on radiative budgets and heating fields in convective regions",2016,"10.1016/j.atmosres.2015.07.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84939435174&doi=10.1016%2fj.atmosres.2015.07.017&partnerID=40&md5=974d1e2e1d99172230e661e76e69d0c0","Impacts of cloud overlap assumptions on radiative budgets and heating fields are explored with the aid of a cloud-resolving model (CRM), which provided cloud geometry as well as cloud micro and macro properties. Large-scale forcing data to drive the CRM are from TRMM Kwajalein Experiment and the Global Atmospheric Research Program's Atlantic Tropical Experiment field campaigns during which abundant convective systems were observed. The investigated overlap assumptions include those that were traditional and widely used in the past and the one that was recently addressed by Hogan and Illingworth (2000), in which the vertically projected cloud fraction is expressed by a linear combination of maximum and random overlap, with the weighting coefficient depending on the so-called decorrelation length L<inf>cf</inf>. Results show that both shortwave and longwave cloud radiative forcings (SWCF/LWCF) are significantly underestimated under maximum (MO) and maximum-random (MRO) overlap assumptions, whereas remarkably overestimated under the random overlap (RO) assumption in comparison with that using CRM inherent cloud geometry. These biases can reach as high as 100 Wm-2 for SWCF and 60 Wm-2 for LWCF. By its very nature, the general overlap (GenO) assumption exhibits an encouraging performance on both SWCF and LWCF simulations, with the biases almost reduced by 3-fold compared with traditional overlap assumptions. The superiority of GenO assumption is also manifested in the simulation of shortwave and longwave radiative heating fields, which are either significantly overestimated or underestimated under traditional overlap assumptions. The study also pointed out the deficiency of constant assumption on L<inf>cf</inf> in GenO assumption. Further examinations indicate that the CRM diagnostic L<inf>cf</inf> varies among different cloud types and tends to be stratified in the vertical. The new parameterization that takes into account variation of L<inf>cf</inf> in the vertical well reproduces such a relationship and leads to better simulations on radiative heating fields. It is therefore desirable to specify or parameterize L<inf>cf</inf> in terms of cloud categories rather than constantly specified if to further improve the model performance. © 2015 Elsevier B.V."
"57192063986;23048575400;7103204204;6603382350;7005174340;","Airborne observations and simulations of three-dimensional radiative interactions between Arctic boundary layer clouds and ice floes",2015,"10.5194/acp-15-8147-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84937773541&doi=10.5194%2facp-15-8147-2015&partnerID=40&md5=93b5e39890ad155c1394463d20dc3fa5","Based on airborne spectral imaging observations, three-dimensional (3-D) radiative effects between Arctic boundary layer clouds and highly variable Arctic surfaces were identified and quantified. A method is presented to discriminate between sea ice and open water under cloudy conditions based on airborne nadir reflectivity γλ measurements in the visible spectral range. In cloudy cases the transition of γλ from open water to sea ice is not instantaneous but horizontally smoothed. In general, clouds reduce γλ above bright surfaces in the vicinity of open water, while γλ above open sea is enhanced. With the help of observations and 3-D radiative transfer simulations, this effect was quantified to range between 0 and 2200 m distance to the sea ice edge (for a dark-ocean albedo of αwater = 0.042 and a sea-ice albedo of αice = 0.91 at 645 nm wavelength). The affected distance ΔL was found to depend on both cloud and sea ice properties. For a low-level cloud at 0-200 m altitude, as observed during the Arctic field campaign VERtical Distribution of Ice in Arctic clouds (VERDI) in 2012, an increase in the cloud optical thickness τ from 1 to 10 leads to a decrease in ΔL from 600 to 250 m. An increase in the cloud base altitude or cloud geometrical thickness results in an increase in ΔL for τ = 1/10 ΔL = 2200 m/1250 m in case of a cloud at 500-1000 m altitude. To quantify the effect for different shapes and sizes of ice floes, radiative transfer simulations were performed with various albedo fields (infinitely long straight ice edge, circular ice floes, squares, realistic ice floe field). The simulations show that ΔL increases with increasing radius of the ice floe and reaches maximum values for ice floes with radii larger than 6 km (500-1000 m cloud altitude), which matches the results found for an infinitely long, straight ice edge. Furthermore, the influence of these 3-D radiative effects on the retrieved cloud optical properties was investigated. The enhanced brightness of a dark pixel next to an ice edge results in uncertainties of up to 90 and 30 % in retrievals of τ and effective radius r<inf>eff</inf>, respectively. With the help of ΔL, an estimate of the distance to the ice edge is given, where the retrieval uncertainties due to 3-D radiative effects are negligible. © Author(s) 2015."
"7006728825;14044750400;57201806565;","High-resolution observations of precipitation from cumulonimbus clouds",2015,"10.1002/met.1492","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921627829&doi=10.1002%2fmet.1492&partnerID=40&md5=dc8d142936b808072a6c124255a590c6","Making high-resolution observations of heavy rainfall from cumulonimbus clouds involves choosing a good location where convection occurs frequently and with some degree of predictability so that aircraft do not have to chase clouds, and radars and other ground-based instruments can be optimally placed. It also requires significant resources, international collaboration and a good deal of serendipity. This paper describes several observational campaigns that were designed to understand relatively small-scale convective clouds that produce heavy precipitation, and presents results that have been found over the years. It complements the companion papers in this special issue by giving an observational perspective. It is by no means comprehensive and is limited to cumulonimbus clouds. The Convective Storm Initiation Project (CSIP) was designed to understand the phenomena responsible for the initiation of convection in the maritime environment of southern England. There was a similar objective in the Convective Orographically-induced Precipitation Study (COPS), but for the complex terrain of the Black Forest mountains, Germany, and the Vosges Mountains, France. The recent Convective Precipitation Experiment (COPE) was designed to understand the entire life cycle of convective clouds that formed along sea-breeze convergence lines in the southwestern peninsula of England. Its particular focus was on the dynamics and microphysics of the convective clouds. Examples of observations from these and other field campaigns designed to study the initiation of convection, cumulonimbus clouds and convective precipitation are presented, with a view to demonstrating how they contribute to a physical understanding of the phenomena and the processes involved. © 2015 Royal Meteorological Society."
"36803253000;35887706900;7003886299;20435752700;6603591733;","On transition-zone water clouds",2014,"10.5194/acp-14-9001-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84906910454&doi=10.5194%2facp-14-9001-2014&partnerID=40&md5=ff3f5b3b38ba845f0ba79378c40a4812","A recent field campaign was conducted to measure the properties of thin, warm convective clouds forming under conditions of weak updrafts. During the campaign, short-lived clouds (on the order of minutes) with droplets' effective radius of 1-2 mum and low liquid water path (∼ 500 mg m2) were measured. These low values are puzzling, since in most studies an effective radius of 4 Î1/4m is reported to serve as the lower bound for clouds. A theoretical cloud model designed to resolve the droplet-activation process suggested conditions that favor the formation of such clouds. Here we show that these clouds, which mark the transition from haze to cloud, are highly sensitive to the magnitude of the initial perturbation that initiated them. We define these clouds as ""transition-zone clouds"". The existence of such clouds poses a key challenge for the analysis of atmospheric observations and models, since they ""further smooth"" the transition from dry aerosol through haze pockets to cumulus clouds. © 2014 Author(s)."
"36646089600;7410255460;","An explosive convective cloud system and its environmental conditions in MJO initiation observed during DYNAMO",2014,"10.1002/2013JD021048","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898828940&doi=10.1002%2f2013JD021048&partnerID=40&md5=df1a55401d03653e129a69efe816358e","An unusually large, explosive convective cloud system was observed over the equatorial Indian Ocean on 28 November 2011 during the DYNAMO (Dynamics of the Madden-Julian Oscillation (MJO)) field campaign. The significance of this mesoscale convective system (MCS) is its size and explosive development of cold cloud tops (96°C) during the initiation of a strong MJO event. Observations from the DYNAMO show that the large MCS developed within a well-defined synoptic-scale cyclonic circulation associated with an equatorial low-pressure system with characteristics of a mixed Rossby-gravity wave that dominated the flow in the DYNAMO array. Prior to the development of the MCS, the equatorial flow was characterized by strong vertical wind shear with low-level westerlies and upper level easterlies. A region of decreased wind shear and enhanced upper level divergence emerged concurrently with the passage of the westward moving mixed Rossby-gravity wave-related low-pressure system and convective activity. In situ sounding observations suggest that widespread deep convection upstream of the large MCS may have contributed to the reduction of the upper level easterlies through vertical momentum transport and convective outflow. Both the reduction in vertical wind shear and enhanced low-level convergence induced by the equatorial low-pressure system created a favorable environment for the rapid development of the MCS. This study examines the development of the MCS and the associated synoptic-scale equatorial low-pressure system within the large-scale MJO circulation using in situ sounding observations from DYNAMO, which provide new insights into the interaction between convection and environmental flow during MJO initiation over the equatorial Indian Ocean. © 2014. American Geophysical Union. All Rights Reserved."
"37561696600;7801634218;6506385754;6602081215;7005729142;","Difficulties in early ice detection with the small ice Detector-2 HIAPER (SID-2H) in maritime cumuli",2014,"10.1175/JTECH-D-13-00079.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84902121904&doi=10.1175%2fJTECH-D-13-00079.1&partnerID=40&md5=eccdfcd0082107e38d474c64f35876e6","The Small Ice Detector, version 2 (SID-2), High-performance Instrumented Airborne Platform for Environmental Research (HIAPER; SID-2H) was used to detect small ice particles in the early stages of ice formation in the high liquid water environment of tropical maritime cumulus clouds sampled during the Ice in Clouds Experiment-Tropical (ICE-T) field campaign. Its performance in comparison to other probes and the development of new corrections applied to the data are presented. The SID-2H detected small ice crystals among larger particles. It correctly identified water drops, and discriminated between round and irregular particle shapes in water-dominated clouds with errors less than 5%. Remaining uncertainties in the sensing volume and the volume over which coincidence of particles occurred, result in the data being used here in a qualitative manner to identify the presence of ice, and its habits and sizes. © 2014 American Meteorological Society."
"47761806800;7404970050;","Predictability and genesis of Hurricane Karl (2010) examined through the EnKF assimilation of field observations collected during PREDICT",2014,"10.1175/JAS-D-13-0291.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897435990&doi=10.1175%2fJAS-D-13-0291.1&partnerID=40&md5=77078bd60c27e3150001dc8de8496d34","The genesis of Hurricane Karl (2010) is explored using analyses and forecasts from a cycling ensemble Kalman filter (EnKF) that assimilates routinely collected observations as well as dropsonde measurements that were taken during the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) field campaign. A total of 127 dropsonde observations were collected from six PREDICT flight missions over a 5-day period before and during Karl's genesis. EnKF analyses that take into account the PREDICT dropsondes provide a detailed four-dimensional overview of the evolving kinematic and thermodynamic structure within the pregenesis disturbance. In particular, the additional field observations are found to increase the low- and midlevel circulation and column moisture in the EnKF analyses and reduce the position error of the low-level vortex. Deterministic forecasts from these analyses show a 24-h improvement in predicting genesis over a control experiment that omits the dropsonde observations. In ensemble forecasts for this event, the more accurate analyses translate into a higher confidence in predicting the intensification of Karl; that is, data assimilation experiments also suggest that initial condition errors at the mesoscale pose large challenges for predicting genesis, thus highlighting the need for improved observation networks and more advanced data assimilation methods. © 2014 American Meteorological Society."
"9940496700;55857912500;57213484786;","Height correction of atmospheric motion vectors using airborne lidar observations",2013,"10.1175/JAMC-D-12-0233.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884277128&doi=10.1175%2fJAMC-D-12-0233.1&partnerID=40&md5=cddee9eeac3cc97446be270e9c2a695c","Uncertainties in the height assignment of atmospheric motion vectors (AMVs) are the main contributor to the total AMV wind error, and these uncertainties introduce errors that can be horizontally correlated over several hundred kilometers. As a consequence, only a small fraction of the availableAMVs are currently used in numerical weather prediction systems. For this reason, alternative approaches for the height assignment of AMVs are investigated in this study: 1) using collocated airborne lidar observations and 2) treating AMVs as layer winds instead of winds at a discrete level. Airborne lidar observations from a field campaign in the western North Pacific Ocean region are used to demonstrate the potential of improving AMV heights in an experimental framework. On average, AMV wind errors are reduced by 10%-15% when AMV winds are assigned to a 100-150-hPa-deep layer beneath the cloud top derived from nearby lidar observations. In addition, the lidar-AMV height correction is expected to reduce the correlation ofAMVerrors as lidars provide independent cloud height information. This suggests that satellite lidars may be a valuable source of information for the AMV height assignment in the future. Furthermore, AMVs are compared with dropsonde and radiosonde winds averaged over vertical layers of different depth to investigate the optimal height assignment for AMVs in data assimilation. Consistent with previous studies, it is shown thatAMVwinds better match sounding winds vertically averaged over ̃100 hPa than sounding winds at a discrete level. The comparison with deeper layers further reduces the RMS difference but introduces systematic differences of wind speeds. © 2013 American Meteorological Society."
"55807962900;6701382162;","Geostationary infrared methods for detecting lightning-producing cumulonimbus clouds",2013,"10.1002/jgrd.50485","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880853374&doi=10.1002%2fjgrd.50485&partnerID=40&md5=ba5b50c2280b3c03859701dc56ba3bab","This study documents the behavior of cloud top infrared (IR) fields known to describe physical processes associated with growing convective clouds, for 30 nonlightning and 33 cloud-to-ground (CG) lightning-producing convective storms. The goal is to define ""critical"" threshold values for up to 10 IR fields that delineate lightning from nonlightning convective storms. Meteosat Second Generation and United Kingdom Meteorological Office very low frequency arrival time difference satellite and lightning data, respectively, were used in this study. These were collected during the National Aeronautics and Space Administration (NASA) African Monsoon Multidisciplinary Analyses (NAMMA) field campaign in August-September 2006 in Equatorial Africa. The main conclusions show that eight of 10 IR fields that describe updraft strength, cloud depth, and glaciation (or ice at cloud top) are significantly different between the nonlightning and lightning-producing convective clouds. The lack of notch overlap in ""box and whiskers"" plots confirms a 95% confidence that the two data sets are different. Nonlightning-producing clouds are far less vertically developed and possess >50% weaker updrafts (as estimated from satellite trends), as well as little to no evidence of ice or glaciation at cloud top. Results from this study therefore can be used to nowcast and identify with high confidence convective clouds that are producing or are going to produce CG lightning using Meteosat data, assuming appropriate tracking of growing cumulus clouds is performed. Key Points Lightning-producing storms can be identified from IR satellite interest fields. MSG SEVIRI infrared data show interest fields for cloud-to-ground lightning. Forecast. method for cloud-to-ground lightning in third world countries. © 2013. American Geophysical Union. All Rights Reserved."
"6603478504;7103174511;7003959453;6602093732;7501416570;","Developing a GeoSTAR science mission",2007,"10.1109/IGARSS.2007.4424041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-58149137872&doi=10.1109%2fIGARSS.2007.4424041&partnerID=40&md5=e7bde1e791a5fb9c2989ed08c1909ac1","The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new instrument design that has been under development at the Jet Propulsion Laboratory in the form of a proof-of-concept prototype. It is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. Such sensors have long been part of low-earth-orbiting (LEO) operational weather satellites and research satellites and have had a major impact ranging from numerical weather prediction to climate research. A similar capability in GEO is highly desired because of the advantageous observing point GEO offers, with continuous views of the entire visible Earth disc - crucial for the observation of hurricanes and other rapidly evolving atmospheric phenomena. GEO also enables full resolution of the diurnal cycle, which is particularly important in the study of atmospheric processes and climate variability where clouds and convection play a role, since those phenomena are known to have strong diurnal variability and are difficult to sample properly with sun synchronous LEO satellites. The GeoSTAR prototype produced the first interferometric radiometric images obtained at sounding frequencies in early 2005, and subsequent tests have demonstrated that the system exhibits excellent stability, accuracy and sensitivity and performs even better than predicted. This can be characterized as a breakthrough development. The technology required to implement GeoSTAR is at a level of maturity that a space mission can be contemplated. Such a mission is recommended by the U.S. National Research Council in its recent Decadal Survey of Earth missions and is being considered by both NASA and NOAA for the coming decade. Recent studies indicate that it is indeed feasible to implement a GeoSTAR mission in the 2014-16 time frame. We discuss possible mission scenarios as well as the science benefits that would ensue. The benefits are particularly significant in the area of tropical cyclones and severe storms, where there currently is a dearth of observations. With a geostationary microwave sounder it is possible to obtain the 3-dimensional distribution of temperature, water vapor and liquid water continuously and regardless of cloud cover, and atmospheric stability indices such as lifted index (LI) and convective available potential energy (CAPE) can be derived nearly everywhere. That will make it possible, for example, to detect severe-storm precursor conditions even if the area is under cloud cover. Recent progress in radiative transfer models now also makes it possible to obtain those parameters in the presence of moderate precipitation, and rain rates and snow rates can be derived as well. Aircraft based field campaign observations have also shown that a microwave sounder can be used to derive measures of convective intensity and precipitation in deep-convective systems from scattering due to ice particles formed by such systems. This can be used to estimate the intensity of tropical cyclones and can be used to detect sudden intensification and weakening in near-real time. © 2007 IEEE."
"7004003763;7201504886;23491820700;22953316500;6602765265;7402049334;7005035762;7202762223;7202381052;7404521962;23491272300;6602761005;23491617300;15724691800;23491742900;39761266700;14019399400;23491760300;23492602300;23492607000;8707388600;7006350707;23492890900;23493263800;8866821900;23493152900;55463274000;20433889200;23493070400;23493230800;55256474600;57198200248;23493780900;23493775500;57208309414;56224407000;23493778600;35264934000;12645126500;23493863300;23494417700;","In the driver's seat: Rico and education",2007,"10.1175/BAMS-88-12-1929","https://www.scopus.com/inward/record.uri?eid=2-s2.0-39049148135&doi=10.1175%2fBAMS-88-12-1929&partnerID=40&md5=38592b9434982fb9a2e8f6c39a6d36b3","The Rain in Cumulus over the Ocean (RICO) field campaign carried out a wide array of educational activities, including a major first in a field project - a complete mission, including research flights, planned and executed entirely by students. This article describes the educational opportunities provided to the 24 graduate and 9 undergraduate students who participated in RICO. © 2008 American Meteorological Society Privacy Policy and Disclaimer."
"7003907406;57206332144;7003289221;7003621869;7005165467;","A missing solution to the transport equation and its effect on estimation of cloud absorptive properties",2002,"10.1175/1520-0469(2002)059<3572:AMSTTT>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346037165&doi=10.1175%2f1520-0469%282002%29059%3c3572%3aAMSTTT%3e2.0.CO%3b2&partnerID=40&md5=60a91ca0ce60b6f2a4afd85cea483f40","Most of the existing cloud radiation models treat liquid water drops of a variety of sizes as an ensemble of particles. The ensemble approach assumes that all drop sizes are well represented in an elementary volume, and its scattering and absorbing properties can be accurately specified through the use of the drop size probability density distribution function. The concentration of large drops, however, can be so low that a chance to capture them in the elementary volume is rare. Thus the drop ensemble assumption is not always true, though classical radiative transfer theory uses this assumption to simplify the radiative transfer process, as if scattering takes place from an ""average drop"" rather than from a particular drop. The theoretical analysis presented in this paper demonstrates that if a cumulative distribution function is used to describe drop size variability with jumps accounting for the probability of finding large drops in the elementary volume, one obtains an extra term, the Green's function, in the solution of the radiative transfer equation. The analysis of data on cloud drop size distribution acquired during the First International Satellite Cloud Climatology Project (ISCCP) Research Experiment (FIRE) field campaign clearly shows jumps in the cumulative drop size distribution: the magnitudes of the jumps are related to the frequencies of large drop occurrence. This discontinuity is primarily responsible for the additional terms that must be added to the solution to properly account for the photon interaction with the large drops. The enhancement of cloud absorption due to accounting for the ""missing solution"" exhibits a jump-like response to continuous variation in the concentration of large drops and may exceed the enhancement predicted by the ensemble-based models. The results presented here indicate that the missing term might be plausible to explain the enhanced value of the ratio of the shortwave cloud forcing at the surface to the forcing at top of the atmosphere."
"7004144532;7202980760;","Incorporation of spectral and directional radiative transfer in a snow model",1999,"10.1002/(SICI)1099-1085(199909)13:12/13<1761::AID-HYP856>3.0.CO;2-Y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033190438&doi=10.1002%2f%28SICI%291099-1085%28199909%2913%3a12%2f13%3c1761%3a%3aAID-HYP856%3e3.0.CO%3b2-Y&partnerID=40&md5=3b3051297e63b0ca6cbe53792f182ccb","A study was conducted to test an advanced physically-based snow energy budget model, SNTHERM, linked with a discrete ordinate radiative transfer model, DISORT, at nine wavelengths assuming spherical snow grains. The fully linked model was tested on a data set from a field campaign on the Uranus Glacier, Antarctica, December 1994-February 1995. Snow pit data were used to initialize the model. The combined model was tested against simpler radiative transfer parameterizations, with variations in grain size and solar zenith angle, or fixed albedo and extinction techniques. Albedo predictions from the discrete ordinate radiative transfer model show large variations in albedo with solar zenith angle and the diffuse and direct spectral radiative split. The spectral method provided superior results for snowpack temperatures over the test period.Present radiative transfer methods in physically based energy budget models of snow do not include adequate spectral or directional resolution to deal with the scattering of solar radiation. This paper reports on results from an advanced physically-based snow energy budget model, SNTHERM, linked with a discrete ordinate radiative transfer model, DISORT, at nine wavelengths assuming spherical snow grains. Scattering properties were averaged over a small range of grain sizes (as seen in real snow) to eliminate interference induced fluctuations. A method was derived to split a single measurement of spectrally integrated solar radiation into its direct and diffuse components at nine wavelengths. The split of radiation is required as input to the radiative transfer model, and is produced as a weighted average from days of total cloud cover and days of clear skies (from the 6S atmosphere radiative transfer model). The fully linked model was tested on a data set from a field campaign on the Uranus Glacier, Antarctica, December 1994-February 1995. An automated weather station provided meteorological inputs, with additional measurements made of solar radiation. A vertical array of thermistors made continuous measurements of snowpack temperature in the top metre of snow, though those thermistors near the surface were contaminated by solar heating and melting. Snow pit data were used to initialize the model. The combined model was tested against simpler radiative transfer parameterizations, with variations in grain size and solar zenith angle, or fixed albedo and extinction techniques. Albedo predictions from the discrete ordinate radiative transfer model show large variations in albedo with solar zenith angle and the diffuse and direct spectral radiative split. The spectral method provided superior results for snowpack temperatures over the test period."
"7006354036;","The Kleiner Feldberg cloud experiment 1990",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028585525&partnerID=40&md5=65ac5285a369565150406fafe7404587","An overview is given of the Kleiner Feldberg cloud experiment performed from 27 October until 13 November 1990. The experiment was carried out by numerous European research groups as a joint effort within the EUROTRAC-GCE project in order to study the interaction of cloud droplets with atmospheric trace constituents. After a description of the observational site and the measurements which were performed, the general cloud formation mechanisms encountered during the experiment are discussed. Special attention is given here to the process of moist adiabatic lifting. Furthermore, an overview is given regarding the pollutant levels in the gas phase, the particulate and the liquid phase, and some major findings are presented with respect to the experimental objectives. Finally, a first comparison attempts to put the results obtained during this campaign into perspective with the previous GCE field campaign in the Po Valley. -from Editor"
"7005421048;","High altitude cloud observations by ground-based lidar, infrared radiometer and Meteosat measurements",1989,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024573065&partnerID=40&md5=047eb7796b60b167c4b9256bf8c48f5b","Several field campaigns have been conducted at the Observatoire de Haute-Provence in southern France (OHP) to study cirrus and high clouds. The backscatter lidar technique is used for two wavelengths in the visible at 0.53 μm for nighttime measurements and in the near infrared at 1.06 μm for daytime measurements. In the present case, the skylight background reduces the signal to noise and limits the lidar operation at 0.53 μm to nighttime only. Observation of cirrus clouds during a one week period have been conducted at various times in 1983-84 at OHP. For an altostratus cloud observed in February 1984, ground-based lidar and infrared radiometric measurements at OHP were coordinated with Meteosat observations. -from Authors"
"36838053400;6602994648;22984791700;56888870100;","Soil organic carbon mapping using LUCAS topsoil database and Sentinel-2 data: An approach to reduce soil moisture and crop residue effects",2019,"10.3390/rs11182121","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072633132&doi=10.3390%2frs11182121&partnerID=40&md5=c8f2fef7fcd96a31d52cb5b5dc2a4c76","Soil organic carbon (SOC) loss is one of the main causes of soil degradation in croplands. Thus, spatial and temporal monitoring of SOC is extremely important, both from the environmental and economic perspective. In this regard, the high temporal, spatial, and spectral resolution of the Sentinel-2 data can be exploited for monitoring SOC contents in the topsoil of croplands. In this study, we aim to test the effect of the threshold for a spectral index linked to soil moisture and crop residues on the performance of SOC prediction models using the Multi-Spectral Instrument (MSI) Sentinel-2 and the European Land Use/cover Area frame Statistical survey (LUCAS) topsoil database. The LUCAS spectral data resampled according to MSI/Sentinel-2 bands, which were used to build SOC prediction models combining pairs of the bands. The SOC models were applied to a Sentinel-2 image acquired in North-Eastern Germany after removing the pixels characterized by clouds and green vegetation. Then, we tested different thresholds of the Normalized Burn Ratio 2 (NBR2) index in order to mask moist soil pixels and those with dry vegetation and crop residues. The model accuracy was tested on an independent validation database and the best ratio of performance to deviation (RPD) was obtained using the average between bands B6 and B5 (Red-Edge Carbon Index: RE-CI) (RPD: 4.4) and between B4 and B5 (Red-Red-Edge Carbon Index: RRE-CI) (RPD: 2.9) for a very low NBR2 threshold (0.05). Employing a higher NBR2 tolerance (higher NBR2 values), the mapped area increases to the detriment of the validation accuracy. The proposed approach allowed us to accurately map SOC over a large area exploiting the LUCAS spectral library and, thus, avoid a new ad hoc field campaign. Moreover, the threshold for selecting the bare soil pixels can be tuned, according to the goal of the survey. The quality of the SOC map for each tolerance level can be judged based on the figures of merit of the model. © 2019 by the authors."
"57193213111;7102266120;57203048897;57189640729;57110466800;6603569074;24491934500;37031473100;7402480218;57190584167;12803904100;7003570692;6507506955;36601171100;7102654014;36170035600;7006027075;7410177774;6701562043;55481489700;7402781278;35276210200;36076994600;34772240500;6506424404;","Overview of the hi-scale field campaign a new perspective on shallow convective clouds",2019,"10.1175/BAMS-D-18-0030.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068564172&doi=10.1175%2fBAMS-D-18-0030.1&partnerID=40&md5=bd146e6119f3ccaaa51c7327363e181f",[No abstract available]
"57193622926;36106370400;37085050600;56387142000;7005069415;57189748029;","Droplet activation behaviour of atmospheric black carbon particles in fog as a function of their size and mixing state",2019,"10.5194/acp-19-2183-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061826927&doi=10.5194%2facp-19-2183-2019&partnerID=40&md5=55cdc664d245f01337a5fd50658dec21","Among the variety of particle types present in the atmosphere, black carbon (BC), emitted by combustion processes, is uniquely associated with harmful effects to the human body and substantial radiative forcing of the Earth. Pure BC is known to be non-hygroscopic, but its ability to acquire a coating of hygroscopic organic and inorganic material leads to increased diameter and hygroscopicity, facilitating droplet activation. This affects BC radiative forcing through aerosol-cloud interactions (ACIs) and BC life cycle. To gain insights into these processes, we performed a field campaign in winter 2015-2016 in a residential area of Zurich which aimed at establishing relations between the size and mixing state of BC particles and their activation to form droplets in fog. This was achieved by operating a CCN counter (CCNC), a scanning mobility particle sizer (SMPS), a single-particle soot photometer (SP2) and an aerosol chemical speciation monitor (ACSM) behind a combination of a total- and an interstitial-aerosol inlet. Our results indicate that in the morning hours of weekdays, the enhanced traffic emissions caused peaks in the number fraction of externally mixed BC particles, which do not act as CCN within the CCNC. The very low effective peak supersaturations (SS peak ) occurring in fog (between approximately 0.03% and 0.06% during this campaign) restrict droplet activation to a minor fraction of the aerosol burden (around 0.5% to 1% of total particle number concentration between 20 and 593nm) leading to very selective criteria on diameter and chemical composition. We show that bare BC cores are unable to activate to fog droplets at such low SS pea , while BC particles surrounded by thick coating have very similar activation behaviour to BC-free particles. Using simplified κ-Köhler theory combined with the ZSR mixing rule assuming spherical core-shell particle geometry constrained with single-particle measurements of respective volumes, we found good agreement between the predicted and the directly observed size- and mixing-state-resolved droplet activation behaviour of BC-containing particles in fog. This successful closure demonstrates the predictability of their droplet activation in fog with a simplified theoretical model only requiring size and mixing state information, which can also be applied in a consistent manner in model simulations. © 2019 Author(s)."
"35768068000;6602898472;14818879800;7201444400;56204469300;35119417000;15030842900;57188812930;57205541821;6504611491;","New RadcalNet site at Gobabeb, Namibia: Installation of the instrumentation and first satellite calibration results",2018,"10.1109/IGARSS.2018.8517716","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060450953&doi=10.1109%2fIGARSS.2018.8517716&partnerID=40&md5=47154ea77a261eb879d916b16acf8910","A new permanently instrumented radiometric calibration site for high/medium resolution imaging satellites in the visible/near-IR has been set up in Gobabeb, Namibia in July 2017. The station location has been decided after a global analysis of satellite data assessing surface spatial homogeneity, cloud coverage, temporal variability, atmospheric turbidity etc. which has been compared with in-situ data (surface reflectance, BRDF etc.) from a field campaign which took place in late 2015. The instrumentation automatically measures atmospheric (aerosol optical thickness etc.) and surface conditions (BRDF) from 414 nm to 1600 nm in 12 narrow spectral bands. The data processing is performed at CNES and includes the calibration of the photometer itself using in-situ measurements, and the simulation of the top-of-atmosphere radiance seen by any optical sensor over-passing the site, thus calibrating the sensor. This paper describes the instrument location, measurement protocol, calibration principle and calibration results of satellites Sentinel2A and Sentinel2B. © 2018 IEEE"
"55624399200;7005304841;7003740015;7003875148;25631411400;24472110700;","The free troposphere as a potential source of arctic boundary layer aerosol particles",2017,"10.1002/2017GL073808","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022100602&doi=10.1002%2f2017GL073808&partnerID=40&md5=dde7c175a0e68eca7d2116b2c4ca7611","This study investigates aerosol particle transport from the free troposphere to the boundary layer in the summertime high Arctic. Observations from the Arctic Summer Cloud Ocean Study field campaign show several occurrences of high aerosol particle concentrations above the boundary layer top. Large-eddy simulations suggest that when these enhanced aerosol concentrations are present, they can be an important source of aerosol particles for the boundary layer. Most particles are transported to the boundary layer by entrainment. However, it is found that mixed-phase stratocumulus clouds, which often extend into the inversion layer, also can mediate the transport of particles into the boundary layer by activation at cloud top and evaporation below cloud base. Finally, the simulations also suggest that aerosol properties at the surface sometimes may not be good indicators of aerosol properties in the cloud layer. ©2017. American Geophysical Union. All Rights Reserved."
"55968364300;56789763900;55241984000;57149740600;57190953520;57193137851;7004715270;7005968859;8586682800;7005773698;","Transport of pollution to a remote coastal site during gap flow from California's interior: Impacts on aerosol composition, clouds, and radiative balance",2017,"10.5194/acp-17-1491-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011094175&doi=10.5194%2facp-17-1491-2017&partnerID=40&md5=97e43e9012496b5a32adb0df1417c385","During the CalWater 2015 field campaign, ground-level observations of aerosol size, concentration, chemical composition, and cloud activity were made at Bodega Bay, CA, on the remote California coast. A strong anthropogenic influence on air quality, aerosol physicochemical properties, and cloud activity was observed at Bodega Bay during periods with special weather conditions, known as Petaluma Gap flow, in which air from California's interior is transported to the coast. This study applies a diverse set of chemical, cloud microphysical, and meteorological measurements to the Petaluma Gap flow phenomenon for the first time. It is demonstrated that the sudden and often dramatic change in aerosol properties is strongly related to regional meteorology and anthropogenically influenced chemical processes in California's Central Valley. In addition, it is demonstrated that the change in air mass properties from those typical of a remote marine environment to properties of a continental regime has the potential to impact atmospheric radiative balance and cloud formation in ways that must be accounted for in regional climate simulations."
"55244684800;57210412109;23011002900;38461378900;24399716000;7103201242;","Why torrential rain occurs on the Western Coast of Sumatra Island at the leading edge of the MJO westerly wind bursts",2017,"10.2151/sola.2017-007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040367641&doi=10.2151%2fsola.2017-007&partnerID=40&md5=71e33de865d3456b762e9c2712191036","This study examined the impact of an active phase of the Madden-Julian Oscillation (MJO) on a torrential rain event that occurred on the western coast of Sumatra Island on 12 December 2015, using surface meteorological observations, meteorological radar observations, and balloon sounding data obtained from the pre-Years of the Maritime Continent field campaign. Strong MJO activity took place in mid-December 2015 into January 2016. Radar observations revealed that a convergence and convective cloud merger of mesoscale convective systems from an eastward propagating MJO and westward moving diurnal convection over the western coast of the island was the immediate cause of the torrential rain. An investigation of the occurrence of convection over the island showed that both westward moving diurnal convection from the mountains and eastward propagating convection from the Indian Ocean occurred on 12 December, because the westerly winds in the lower troposphere associated with the MJO were only just initiated and were weak on the day. The results suggest that the leading edge of the MJO westerly wind bursts provided favorable conditions for an active phase of the MJO to work with the westward moving diurnal convection and cause torrential rain on the western coast of Sumatra Island. © 2017, the Meteorological Society of Japan."
"14019399400;6603431534;","On the controls of daytime precipitation in the Amazonian dry season",2016,"10.1175/JHM-D-16-0101.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007162484&doi=10.1175%2fJHM-D-16-0101.1&partnerID=40&md5=784bbbd2c66b852350c5ca8e508e0f9f","The Amazon plays an important role in the global energy and hydrological budgets. The precipitation during the dry season (June-September) plays a critical role inmaintaining the extent of the rain forest. The deployment of the first Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF-1) in the context of the Green OceanAmazon (GOAmazon) field campaign at Manacapuru, Brazil, provided comprehensive measurements of surface, cloud, precipitation, radiation, and thermodynamic properties for two complete dry seasons (2014 and 2015). The precipitation events occurring during the nighttime were associated with propagating storm systems (nonlocal effects), while the daytime precipitation events were primarily a result of local land-atmosphere interactions. During the two dry seasons, precipitation was recorded at the surface on 106 days (43%) from158 rain events with 82 daytime precipitation events occurring on 64 days (60.37%). Detailed comparisons between the diurnal cycles of surface and profile properties between days with and without daytime precipitation suggested the increased moisture at lowand midlevels to be responsible for lowering the lifting condensation level, reducing convective inhibition and entrainment, and thus triggering the transition from shallow to deep convection. Although the monthly accumulated rainfall decreased during the progression of the dry season, the contribution of daytime precipitation to it increased, suggesting the decrease to be mainly due to reduction in propagating squall lines. The control of daytime precipitation during the dry season on large-scale moisture advection above the boundary layer and the total rainfall on propagating squall lines suggests that coarse-resolutionmodels should be able to accurately simulate the dry season precipitation over the Amazon basin. © 2016 American Meteorological Society."
"55958422800;55228409700;7403077486;57203348817;","Aerosol impacts on thermally driven orographic convection",2016,"10.1175/JAS-D-15-0320.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982291464&doi=10.1175%2fJAS-D-15-0320.1&partnerID=40&md5=394bcc2cbc0a7d87cde4759caafa44bb","Observations from the Dominica Experiment (DOMEX) field campaign clearly show aerosols having an impact on cloud microphysical properties in thermally driven orographic clouds. It is hypothesized that when convection is forced by island surface heating, aerosols from the mostly forested island surface are lofted into the clouds, resulting in the observed high concentration of aerosols and the high concentration of small cloud droplets. When trying to understand the impact of these surface-based aerosols on precipitation, however, observed differences in cloud-layer moisture add to the complexity. The WRF Model with the aerosol-aware Thompson microphysics scheme is used to study six idealized scenarios of thermally driven island convection: with and without a surface aerosol source, with a relatively dry cloud layer and with a moist cloud layer, and with no wind and with a weak background wind. It is found that at least a weak background wind is needed to ensure Dominica-relevant results and that the effect of cloud-layer moisture on cloud and precipitation formation dominates over the effect of aerosol. The aerosol impact is limited by the dominance of precipitation formation through accretion. Nevertheless, in order to match observed cloud microphysical properties and precipitation, both a relatively dry cloud layer and a surface aerosol source are needed. The impact of a surface aerosol source on precipitation is strongest when the environment is not conducive to cloud growth. © 2016 American Meteorological Society."
"6701412834;56677549900;9233163800;","Remote sensing of cirrus cloud microphysical properties using spectral measurements over the full range of their thermal emission",2016,"10.1002/2016JD025162","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988826448&doi=10.1002%2f2016JD025162&partnerID=40&md5=966dff97d967bc1adc83c2d1091a47e0","The thermal emission of cirrus clouds, spectrally resolved in the 100–1400 cm−1 range (100–7.1 μm), has been modeled and compared with measurements performed during two field campaigns from the ground-based site of Testa Grigia on the Italian Alps at 3480 m of altitude. The analysis of cirrus microphysics, through spectral fitting, shows the importance of using also the far infrared portion of the emitted spectrum at wave numbers below the 667 cm−1 carbon dioxide absorption band, where only a few measurements exist because of the high opacity of the atmosphere caused by the strong water vapor absorption. The resulted distribution of the fitted cloud parameters is in good agreement with the typical statistical distribution of the midlatitude cirrus cloud parameters. © 2016. American Geophysical Union. All Rights Reserved."
"25823818000;7410255460;","Subsidence warming as an underappreciated ingredient in tropical cyclogenesis. Part I: Aircraft observations",2015,"10.1175/JAS-D-14-0366.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84950318895&doi=10.1175%2fJAS-D-14-0366.1&partnerID=40&md5=a2077ef8de3e84b7d09c145339908a58","The development of a compact warm core extending from the mid-upper levels to the lower troposphere and related surface pressure falls leading to tropical cyclogenesis (TC genesis) is not well understood. This study documents the evolution of the three-dimensional thermal structure during the early developing stages of Typhoons Fanapi and Megi using aircraft dropsonde observations from the Impact of Typhoons on the Ocean in the Pacific (ITOP) field campaign in 2010. Prior to TC genesis, the precursor disturbances were characterized by warm (cool) anomalies above (below) the melting level (~550 hPa) with small surface pressure perturbations. Onion-shaped skew T-logp profiles, which are a known signature of mesoscale subsidence warming induced by organized mesoscale convective systems (MCSs), are ubiquitous throughout the ITOP aircraft missions from the precursor disturbance to the tropical storm stages. The warming partially erodes the lower-troposphere (850-600 hPa) cool anomalies. This warming results in increased surface pressure falls when superposed with the upper-troposphere warm anomalies associated with the long-lasting MCSs/cloud clusters. Hydrostatic pressure analysis suggests the upper-level warming alone would not result in the initial sea level pressure drop associated with the transformation from a disturbance to a TC. As Fanapi and Megi intensify into strong tropical storms, aircraft flight-level (700 hPa) and dropsonde data reveal that the warm core extends down to 850-600 hPa and has some characteristics of subsidence warming similar to the eyes of mature TCs. © 2015 American Meteorological Society."
"7103204204;7005174340;","Reconstruction of high-resolution time series from slow-response broadband terrestrial irradiance measurements by deconvolution",2015,"10.5194/amt-8-3671-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84941550622&doi=10.5194%2famt-8-3671-2015&partnerID=40&md5=18417a91fe25bb05b075689e83d2137c","Broadband solar and terrestrial irradiance measurements of high temporal resolution are needed to study inhomogeneous clouds or surfaces and to derive vertical profiles of heating/cooling rates at cloud top. An efficient method to enhance the temporal resolution of slow-response measurements of broadband terrestrial irradiance using pyrgeometer is introduced. It is based on the deconvolution theorem of Fourier transform to restore amplitude and phase shift of high frequent fluctuations. It is shown that the quality of reconstruction depends on the instrument noise, the pyrgeometer response time and the frequency of the oscillations. The method is tested in laboratory measurements for synthetic time series including a boxcar function and periodic oscillations using a CGR-4 pyrgeometer with response time of 3 s. The originally slow-response pyrgeometer data were reconstructed to higher resolution and compared to the predefined synthetic time series. The reconstruction of the time series worked up to oscillations of 0.5 Hz frequency and 2 W m-2 amplitude if the sampling frequency of the data acquisition is 16 kHz or higher. For oscillations faster than 2 Hz, the instrument noise exceeded the reduced amplitude of the oscillations in the measurements and the reconstruction failed. The method was applied to airborne measurements of upward terrestrial irradiance from the VERDI (Vertical Distribution of Ice in Arctic Clouds) field campaign. Pyrgeometer data above open leads in sea ice and a broken cloud field were reconstructed and compared to KT19 infrared thermometer data. The reconstruction of amplitude and phase shift of the deconvoluted data improved the agreement with the KT19 data. Cloud top temperatures were improved by up to 1 K above broken clouds of 80-800 m size (1-10 s flight time) while an underestimation of 2.5 W m2 was found for the upward irradiance over small leads of about 600 m diameter (10 s flight time) when using the slow-response data. The limitations of the method with respect to instrument noise and digitalization of measurements by the data acquisition are discussed. © Author(s) 2015."
"15837499300;57151201700;16646757400;57150931000;57151428200;","Studies of Cloud Characteristics Related to Jet Engine Ice Crystal Icing Utilizing Infrared Satellite Imagery",2015,"10.4271/2015-01-2086","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959517886&doi=10.4271%2f2015-01-2086&partnerID=40&md5=62578c08bcbd9ae9251f89ac3fe82556","The significant problem of engine power-loss and damage associated with ice crystal icing (ICI) was first formally recognized by the industry in a 2006 publication [1]. Engine events described by the study included: engine surge, stall, flameout, rollback, and compressor damage; which were triggered by the ingestion of ice crystals in high concentrations generated by deep, moist convection. Since 2003, when ICI engine events were first identified, Boeing has carefully analyzed event conditions documenting detailed pilot reports and compiling weather analyses into a database. The database provides valuable information to characterize environments associated with engine events. It provides boundary conditions, exposure times, and severity to researchers investigating the ICI phenomenon. Ultimately, this research will aid in the development of engine tests and ICI detection/avoidance devices or techniques. This paper first provides a detailed examination of the ICI engine event database from a statistical perspective. Environments sampled during the 2014 HAIC-HIWC field campaign, based in Darwin, Australia, are compared to the ICI engine database and it is shown that test flights fell within the expected range of conditions. A new, novel approach to track mesoscale motion of convectively generated ice is introduced. The Mesoscale convective Ice Following (MIF) model uses infrared satellite (IR) cloud top data in conjunction with vertical wind profiles in an attempt to improve upon the detection of high ice water content (HIWC) regions embedded with mesoscale convective systems (MCS). Finally, a preliminary assessment is made of MIF model results using in-situ ice concentration measurements for verification. Copyright © 2015 SAE International."
"18133268300;","Space-based retrieval of NO2 over biomass burning regions: Quantifying and reducing uncertainties",2014,"10.5194/amt-7-3431-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84908053873&doi=10.5194%2famt-7-3431-2014&partnerID=40&md5=5ff06c28a95ead30ecf367904444492b","The accuracy of space-based nitrogen dioxide (NO2) retrievals from solar backscatter radiances critically depends on a priori knowledge of the vertical profiles of NO2 and aerosol optical properties. This information is used to calculate an air mass factor (AMF), which accounts for atmospheric scattering and is used to convert the measured line-of-sight ""slant"" columns into vertical columns. In this study we investigate the impact of biomass burning emissions on the AMF in order to quantify NO2 retrieval errors in the Ozone Monitoring Instrument (OMI) products over these sources. Sensitivity analyses are conducted using the Linearized Discrete Ordinate Radiative Transfer (LIDORT) model. The NO2 and aerosol profiles are obtained from a 3-D chemistry-transport model (GEOS-Chem), which uses the Fire Locating and Monitoring of Burning Emissions (FLAMBE) daily biomass burning emission inventory. Aircraft in situ data collected during two field campaigns, the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) and the Dust and Biomass-burning Experiment (DABEX), are used to evaluate the modeled aerosol optical properties and NO2 profiles over Canadian boreal fires and West African savanna fires, respectively. Over both domains, the effect of biomass burning emissions on the AMF through the modified NO2 shape factor can be as high as -60%. A sensitivity analysis also revealed that the effect of aerosol and shape factor perturbations on the AMF is very sensitive to surface reflectance and clouds. As an illustration, the aerosol correction can range from -20 to +100% for different surface reflectances, while the shape factor correction varies from -70 to -20%. Although previous studies have shown that in clear-sky conditions the effect of aerosols on the AMF was in part implicitly accounted for by the modified cloud parameters, here it is suggested that when clouds are present above a surface layer of scattering aerosols, an explicit aerosol correction would be beneficial to the NO2 retrieval. Finally, a new method that uses slant column information to correct for shape-factor-related AMF error over NOx emission sources is proposed, with possible application to near-real-time OMI retrievals. © 2014 Author(s)."
"37661167800;7202607188;24587715900;6701772538;6603955469;6603604042;17434636400;6602516156;7005453641;7102011023;","Arctic stratospheric dehydration - Part 2: Microphysical modeling",2014,"10.5194/acp-14-3231-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897474802&doi=10.5194%2facp-14-3231-2014&partnerID=40&md5=205e16a314828bcebbf645d9778def5e","Large areas of synoptic-scale ice PSCs (polar stratospheric clouds) distinguished the Arctic winter 2009/2010 from other years and revealed unprecedented evidence of water redistribution in the stratosphere. A unique snapshot of water vapor repartitioning into ice particles was obtained under extremely cold Arctic conditions with temperatures around 183 K. Balloon-borne, aircraft and satellite-based measurements suggest that synoptic-scale ice PSCs and concurrent reductions and enhancements in water vapor are tightly linked with the observed de- and rehydration signatures, respectively. In a companion paper (Part 1), water vapor and aerosol backscatter measurements from the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) and LAPBIAT-II (Lapland Atmosphere-Biosphere Facility) field campaigns have been analyzed in detail. This paper uses a column version of the Zurich Optical and Microphysical box Model (ZOMM) including newly developed NAT (nitric acid trihydrate) and ice nucleation parameterizations. Particle sedimentation is calculated in order to simulate the vertical redistribution of chemical species such as water and nitric acid. Despite limitations given by wind shear and uncertainties in the initial water vapor profile, the column modeling unequivocally shows that (1) accounting for small-scale temperature fluctuations along the trajectories is essential in order to reach agreement between simulated optical cloud properties and observations, and (2) the use of recently developed heterogeneous ice nucleation parameterizations allows the reproduction of the observed signatures of de- and rehydration. Conversely, the vertical redistribution of water measured cannot be explained in terms of homogeneous nucleation of ice clouds, whose particle radii remain too small to cause significant dehydration. © Author(s) 2014."
"9043417100;7102132806;7202957110;8670222900;8684037700;7006235542;57195257572;7006377579;21933618400;35740180800;","Can aerosols influence deep tropical convection? Aerosol indirect effects in the Hector island thunderstorm",2013,"10.1002/qj.2083","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84890248755&doi=10.1002%2fqj.2083&partnerID=40&md5=31339736dc351fa011d10428e7dd491d","This article addresses the effects of cloud condensation nuclei on the evolution of an intense tropical convective system, known as Hector, using data taken from the ACTIVE and TWP-ICE field campaigns, which were conducted in 2005 and 2006. The Hector thunderstorms were observed in a variety of aerosol conditions so the data serve as an ideal dataset to test whether aerosols have a significant impact on the evolution of convective clouds and precipitation. We find evidence for an aerosol effect on the storm's properties, which are reproduced with a state-of-the-art mesoscale cloud-resolving model. Including the measured aerosol concentration within the model is shown to improve the fractions skill-score metric for every case presented in the article, thus giving us confidence that the deep convection observed during the period was indeed influenced by the aerosol entering the storm's inflow. However, we do not find a general relationship for the way aerosols affect properties such as cloud-top height, precipitation or radiative properties, as has been suggested in previous work. The reasons for this appear to be because of the nonlinearity of interactions between neighbouring cells and because of the variability in the meteorological profiles of temperature, wind and humidity. © 2012 Royal Meteorological Society."
"55480948700;6603813334;55480598500;15021192500;23027816700;6701660605;6603581921;","Validation of the FALL3D model for the 2008 chaitén eruption using field and satellite data [Validación del modelo FALL3D para la erupción del Chaitén en 2008 usando datos satelitales y de campo]",2013,"10.5027/andgeoV40n2-a05","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877919732&doi=10.5027%2fandgeoV40n2-a05&partnerID=40&md5=344a7c4c5c8306182a1fb52c5da66c17","The 2008 Chaitén Volcano eruption began on 2 May 2008 with an explosive phase that injected large amounts of tephra into the atmosphere. During the first week of the eruption, volcanic ash clouds were transported for hundreds of kilometres over Argentina by the prevailing westerly winds. Tephra deposition extended to the Atlantic Ocean and severely affected the Argentinean Patagonia. Impacts included air and water quality degradation, disruption of ground transportation systems and cancellation of flights at airports more than 1,500 km apart. We use the FALL3D tephra transport model coupled with the Weather Research and Forecasting-Advanced Research Weather (WRF-ARW) meteorological model to simulate tephra fall from the 2-9 May 2008 eruptive period. Our hindcast results are in good agreement with satellite imagery and reproduce ground deposit observations. Key aspects of our analysis, not considered during syn-eruptive forecasts, are the re-initialization of each simulation with actualized meteorological forecast cycles and better constrained model inputs including column heights (inferred from reanalysis of GOES-10 imagery and nearby atmospheric soundings) and granulometric data obtained from field campaigns. This study shows the potential of coupling WRF/ARW and FALL3D models for short-term forecast of volcanic ash clouds. Our results highlight that, in order to improve forecasting of ash cloud dispersion and tephra deposition, it is essential to implement an operational observation system to measure temporal variations of column height and granulometric characteristics of tephra particles in nearly real-time, at proximal as well as distal locations."
"22933641400;26427744500;7102294773;6603201426;36892703600;35760600800;7006461606;55624488227;7201483081;6602298788;6506458269;7006497590;","Meteorological and air quality forecasting using the WRF-STEM model during the 2008 ARCTAS field campaign",2011,"10.1016/j.atmosenv.2011.02.073","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80755175804&doi=10.1016%2fj.atmosenv.2011.02.073&partnerID=40&md5=620814db273ea8c3f9210a36af50431c","In this study, the University of Iowa's Chemical Weather Forecasting System comprising meteorological predictions using the WRF model, and off-line chemical weather predictions using tracer and full chemistry versions of the STEM model, designed to support the flight planning during the ARCTAS 2008 mission is described and evaluated. The system includes tracers representing biomass burning and anthropogenic emissions from different geographical emissions source regions, as well as air mass age indicators. We demonstrate how this forecasting system was used in flight planning and in the interpretation of the experimental data obtained through the case study of the summer mission ARCTAS DC-8 flight executed on July 9 2008 that sampled near the North Pole. The comparison of predicted meteorological variables including temperature, pressure, wind speed and wind direction against the flight observations shows that the WRF model is able to correctly describe the synoptic circulation and cloud coverage in the Arctic region The absolute values of predicted CO match the measured CO closely suggesting that the STEM model is able to capture the variability in observations within the Arctic region. The time-altitude cross sections of source region tagged CO tracers along the flight track helped in identifying biomass burning (from North Asia) and anthropogenic (largely China) as major sources contributing to the observed CO along this flight. The difference between forecast and post analysis biomass burning emissions can lead to significant changes (~10-50%) in primary CO predictions reflecting the large uncertainty associated with biomass burning estimates and the need to reduce this uncertainty for effective flight planning. © 2011 Elsevier ltd."
"23492890900;7006728825;55663817800;","Early evolution of the largest-sized droplets in maritime cumulus clouds",2010,"10.1002/qj.597","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953079867&doi=10.1002%2fqj.597&partnerID=40&md5=e0773d088d946ea9e46f7e56cbd68f2c","Droplet size distributions (DSDs) measured within a distance of approximately 1km above the base of shallow maritime cumulus clouds during the Rain in Cumulus over the Ocean (RICO) field campaign are compared with results of a condensation and stochastic coalescence model, run in the framework of a closed parcel. New measurements of cloud droplets in the critical size range of 30 to 100μm are presented from the 2D-S probe. Observations are also presented of the large-size tail of the sub-cloud aerosol size distribution measured by the forward-scattering spectrometer probe. Results show that droplet growth in this region is dominated by condensation, and the large-size tail of the observed DSDs can be explained with the observed sub-cloud particles, including giant and ultra-giant aerosols. © 2010 Royal Meteorological Society."
"7003414581;16642991200;55444637900;22954523900;8927405700;57202475063;36651412700;38760907700;15923105200;6602085876;8980175400;17341189400;","Ice-nucleating particle versus ice crystal number concentrationin altocumulus and cirrus layers embedded in Saharan dust:a closure study",2019,"10.5194/acp-19-15087-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072129265&doi=10.5194%2facp-19-15087-2019&partnerID=40&md5=2f85982188e3f23a3577b4da6d87ff59","For the first time, a closure study of the relationship between the ice-nucleating particle concentration (INP; INPC) and ice crystal number concentration (ICNC) in altocumulus and cirrus layers, solely based on groundbased active remote sensing, is presented. Such aerosol- cloud closure experiments are required (a) to better understand aerosol-cloud interaction in the case of mixed-phase clouds, (b) to explore to what extent heterogeneous ice nucleation can contribute to cirrus formation, which is usually controlled by homogeneous freezing, and (c) to check the usefulness of available INPC parameterization schemes, applied to lidar profiles of aerosol optical and microphysical properties up to the tropopause level. The INPC-ICNC closure studies were conducted in Cyprus (Limassol and Nicosia) during a 6-week field campaign in March-April 2015 and during the 17-month CyCARE (Cyprus Clouds Aerosol and Rain Experiment) campaign. The focus was on altocumulus and cirrus layers which developed in pronounced Saharan dust layers at heights from 5 to 11 km. As a highlight, a long-lasting cirrus event was studied which was linked to the development of a very strong dust-infused baroclinic storm (DIBS) over Algeria. The DIBS was associated with strong convective cloud development and lifted large amounts of Saharan dust into the upper troposphere, where the dust influenced the evolution of an unusually large anvil cirrus shield and the subsequent transformation into an cirrus uncinus cloud system extending from the eastern Mediterranean to central Asia, and thus over more than 3500 km. Cloud top temperatures of the three discussed closure study cases ranged from - 20 to -57 °C. The INPC was estimated from polarization/Raman lidar observations in combination with published INPC parameterization schemes, whereas the ICNC was retrieved from combined Doppler lidar, aerosol lidar, and cloud radar observations of the terminal velocity of falling ice crystals, radar reflectivity, and lidar backscatter in combination with the modeling of backscattering at the 532 and 8.5 mm wavelengths. A good-to-acceptable agreement between INPC (observed before and after the occurrence of the cloud layer under investigation) and ICNC values was found in the discussed three proof-of-concept closure experiments. In these case studies, INPC and ICNC values matched within an order of magnitude (i.e., within the uncertainty ranges of the INPC and ICNC estimates), and they ranged from 0.1 to 10 L-1 in the altocumulus layers and 1 to 50 L-1 in the cirrus layers observed between 8 and 11 km height. The successful closure experiments corroborate the important role of heterogeneous ice nucleation in atmospheric ice formation processes when mineral dust is present. The observed longlasting cirrus event could be fully explained by the presence of dust, i.e., without the need for homogeneous ice nucleation processes. © 2019 Author(s)."
"56321122100;7102128820;7102354961;36458602300;6602515941;57211045711;","The importance of particle size distribution and internal structure for triple-frequency radar retrievals of the morphology of snow",2019,"10.5194/amt-12-4993-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072386564&doi=10.5194%2famt-12-4993-2019&partnerID=40&md5=9ae7db613c109488e59131169e8962d2","The accurate representation of ice particles is essential for both remotely sensed estimates of clouds and precipitation and numerical models of the atmosphere. As it is typical in radar retrievals to assume that all snow is composed of aggregate snowflakes, both denser rimed snow and the mixed-phase cloud in which riming occurs may be under-diagnosed in retrievals and therefore difficult to evaluate in weather and climate models. Recent experimental and numerical studies have yielded methods for using triple-frequency radar measurements to interrogate the internal structure of aggregate snowflakes and to distinguish more dense and homogeneous rimed particles from aggregates.</p> <p>In this study we investigate which parameters of the morphology and size distribution of ice particles most affect the triple-frequency radar signature and must therefore be accounted for in order to carry out triple-frequency radar retrievals of snow. A range of ice particle morphologies are represented, using a fractal representation for the internal structure of aggregate snowflakes and homogeneous spheroids to represent graupel-like particles; the mass-size and area-size relations are modulated by a density factor. We find that the particle size distribution (PSD) shape parameter and the parameters controlling the internal structure of aggregate snowflakes both have significant influences on triple-frequency radar signature and are at least as important as that of the density factor. We explore how these parameters may be allowed to vary in order to prevent triple-frequency radar retrievals of snow from being over-constrained, using two case studies from the Biogenic Aerosols-Effects of Clouds and Climate (BAECC) 2014 field campaign at Hyytiälä, Finland. In a case including heavily rimed snow followed by large aggregate snowflakes, we show that triple-frequency radar measurements provide a strong constraint on the PSD shape parameter, which can be estimated from an ensemble of retrievals; however, resolving variations in the PSD shape parameter has a limited impact on estimates of snowfall rate from radar. Particle density is more effectively constrained by the Doppler velocity than triple-frequency radar measurements, due to the strong dependence of particle fall speed on density. Due to the characteristic signatures of aggregate snowflakes, a third radar frequency is essential for effectively constraining the size of large aggregates. In a case featuring rime splintering, differences in the internal structures of aggregate snowflakes are revealed in the triple-frequency radar measurements. We compare retrievals assuming different aggregate snowflake models against in situ measurements at the surface and show significant uncertainties in radar retrievals of snow rate due to changes in the internal structure of aggregates. The importance of the PSD shape parameter and snowflake internal structure to triple-frequency radar retrievals of snow highlights that the processes by which ice particles interact may need to be better understood and parameterized before triple-frequency radar measurements can be used to constrain retrievals of ice particle morphology. © 2019 Author(s)."
"55663817800;39561656500;7202081585;56463153400;41261567800;57195257572;9043417100;7003445775;7102591209;57210991168;7005729142;7202057166;7004242319;17347195800;6701754792;7401639583;8309699900;57213382855;7003406689;35572096100;7006329853;7402838215;","A Review of Ice Particle Shapes in Cirrus formed In Situ and in Anvils",2019,"10.1029/2018JD030122","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072200406&doi=10.1029%2f2018JD030122&partnerID=40&md5=5260adf8efb361a72e86ff6e5edee01f","Results from 22 airborne field campaigns, including more than 10 million high-resolution particle images collected in cirrus formed in situ and in convective anvils, are interpreted in terms of particle shapes and their potential impact on radiative transfer. Emphasis is placed on characterizing ice particle shapes in tropical maritime and midlatitude continental anvil cirrus, as well as in cirrus formed in situ in the upper troposphere, and subvisible cirrus in the upper tropical troposphere layer. There is a distinctive difference in cirrus ice particle shapes formed in situ compared to those in anvils that are generated in close proximity to convection. More than half the mass in cirrus formed in situ are rosette shapes (polycrystals and bullet rosettes). Cirrus formed from fresh convective anvils is mostly devoid of rosette-shaped particles. However, small frozen drops may experience regrowth downwind of an aged anvil in a regime with RHice &gt; ~120% and then grow into rosette shapes. Identifiable particle shapes in tropical maritime anvils that have not been impacted by continental influences typically contain mostly single plate-like and columnar crystals and aggregates. Midlatitude continental anvils contain single-rimed particles, more and larger aggregates with riming, and chains of small ice particles when in a highly electrified environment. The particles in subvisible cirrus are &lt; ~100 μm and quasi-spherical with some plates and rare trigonal shapes. Percentages of particle shapes and power laws relating mean particle area and mass to dimension are provided to improve parameterization of remote retrievals and numerical simulations. ©2019. American Geophysical Union. All Rights Reserved."
"6602364115;56648175200;24070505800;57209470926;55935063200;22954523900;7103357902;7003922583;","Local and Remote Controls on Arctic Mixed-Layer Evolution",2019,"10.1029/2019MS001671","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068751148&doi=10.1029%2f2019MS001671&partnerID=40&md5=a3144f5720ecda78ea311b467ed91801","In this study Lagrangian large-eddy simulation of cloudy mixed layers in evolving warm air masses in the Arctic is constrained by in situ observations from the recent PASCAL field campaign. A key novelty is that time dependence is maintained in the large-scale forcings. An iterative procedure featuring large-eddy simulation on microgrids is explored to calibrate the case setup, inspired by and making use of the typically long memory of Arctic air masses for upstream conditions. The simulated mixed-phase clouds are part of a turbulent mixed layer that is weakly coupled to the surface and is occasionally capped by a shallow humidity layer. All eight simulated mixed layers exhibit a strong time evolution across a range of time scales, including diurnal but also synoptic fingerprints. A few cases experience rapid cloud collapse, coinciding with a rapid decrease in mixed-layer depth. To gain insight, composite budget analyses are performed. In the mixed-layer interior the heat and moisture budgets are dominated by turbulent transport, radiative cooling, and precipitation. However, near the thermal inversion the large-scale vertical advection also contributes significantly, showing a distinct difference between subsidence and upsidence conditions. A bulk mass budget analysis reveals that entrainment deepening behaves almost time-constantly, as long as clouds are present. In contrast, large-scale subsidence fluctuates much more strongly and can both counteract and boost boundary-layer deepening resulting from entrainment. Strong and sudden subsidence events following prolonged deepening periods are found to cause the cloud collapses, associated with a substantial reduction in the surface downward longwave radiative flux. ©2019. The Authors."
"23065650200;7006525200;7006577245;56463153400;","CALIPSO (IIR-CALIOP) retrievals of cirrus cloud ice-particle concentrations",2018,"10.5194/acp-18-17325-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058193757&doi=10.5194%2facp-18-17325-2018&partnerID=40&md5=71650a229ec33dfbe699ee925da10c6b","A new satellite remote sensing method is described whereby the sensitivity of thermal infrared wave resonance absorption to small ice crystals is exploited to estimate cirrus cloud ice-particle number concentration N, effective diameter De and ice water content IWC. This method uses co-located observations from the Infrared Imaging Radiometer (IIR) and from the CALIOP (Cloud and Aerosol Lidar with Orthogonal Polarization) lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) polar orbiting satellite, employing IIR channels at 10.6 and 12.05 μm. Using particle size distributions measured over many flights of the TC4 (Tropical Composition, Cloud and Climate Coupling) and the mid-latitude SPARTICUS (Small Particles in Cirrus) field campaigns, we show for the first time that N=IWC is tightly related to /eff; the ratio of effective absorption optical depths at 12.05 and 10.6 μm. Relationships developed from in situ aircraft measurements are applied to eff derived from IIR measurements to retrieve N. This satellite remote sensing method is constrained by measurements of eff from the IIR and is by essence sensitive to the smallest ice crystals. Retrieval uncertainties are discussed, including uncertainties related to in situ measurement of small ice crystals (D < 15 μm), which are studied through comparisons with IIR eff. The method is applied here to single-layered semi-Transparent clouds having a visible optical depth between about 0.3 and 3, where cloud base temperature is 235 K. CALIPSO data taken over 2 years have been analyzed for the years 2008 and 2013, with the dependence of cirrus cloud N and De on altitude, temperature, latitude, season (winter vs. summer) and topography (land vs. ocean) described. The results for the mid-latitudes show a considerable dependence on season. In the high latitudes, N tends to be highest and De smallest, whereas the opposite is true for the tropics. The frequency of occurrence of these relatively thick cirrus clouds exhibited a strong seasonal dependence in the high latitudes, with the occurrence frequency during Arctic winter being at least twice that of any other season. Processes that could potentially explain some of these micro-and macroscopic cloud phenomena are discussed. © 2018 Author(s)."
"6701669739;57204823046;7003283811;6701653010;57211301037;7005729142;6506385754;","Nonparametric methodology to estimate precipitating ice from multiple-frequency radar reflectivity observations",2018,"10.1175/JAMC-D-18-0036.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057397022&doi=10.1175%2fJAMC-D-18-0036.1&partnerID=40&md5=caadf01be8d9d4040464124479e6cd30","In this study, a nonparametric method to estimate precipitating ice from multiple-frequency radar observations is investigated. The method does not require any assumptions regarding the distribution of ice particle sizes and relies on an efficient search procedure to incorporate information from observed particle size distributions (PSDs) in the estimation process. Similar to other approaches rooted in optimal-estimation theory, the nonparametric method is robust in the presence of noise in observations and uncertainties in the forward models. Over 200 000 PSDs derived from in situ observations collected during the Olympic Mountains Experiment (OLYMPEX) and Integrated Precipitation and Hydrology Experiment (IPHEX) field campaigns are used in the development and evaluation of the nonparametric estimation method. These PSDs are used to create a database of ice-related variables and associated computed radar reflectivity factors at the Ku, Ka, and W bands. The computed reflectivity factors are used to derive precipitating ice estimates and investigate the associated errors and uncertainties. The method is applied to triple-frequency radar observations collected during OLYMPEX and IPHEX. Direct comparisons of estimated ice variables with estimates from in situ instruments show results consistent with the error analysis. Global application of the method requires an extension of the supporting PSD database, which can be achieved through the processing of information from additional past and future field campaigns. © 2018 American Meteorological Society."
"57200123456;7004715270;26022467200;55481489700;56518267700;55253694900;9846154100;7801565183;6701810892;57190947670;7004027519;57203053317;15923105200;","Background Free-Tropospheric Ice Nucleating Particle Concentrations at Mixed-Phase Cloud Conditions",2018,"10.1029/2018JD028338","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053443665&doi=10.1029%2f2018JD028338&partnerID=40&md5=c0f156bc9a7a2999c4fd7ae95f2f0a62","Clouds containing ice are vital for precipitation formation and are important in determining the Earth's radiative budget. However, primary formation of ice in clouds is not fully understood. In the presence of ice nucleating particles (INPs), the phase change to ice is promoted, but identification and quantification of INPs in a natural environment remains challenging because of their low numbers. In this paper, we quantify INP number concentrations in the free troposphere (FT) as measured at the High Altitude Research Station Jungfraujoch (JFJ), during the winter, spring, and summer of the years 2014–2017. INPs were measured at conditions relevant for mixed-phase cloud formation at T = 241/242 K. To date, this is the longest timeline of semiregular measurements akin to online INP monitoring at this site and sampling conditions. We find that INP concentrations in the background FT are on average capped at 10/stdL (liter of air at standard conditions [T = 273 K and p = 1013 hPa]) with an interquartile range of 0.4–9.6/stdL, as compared to measurements during times when other air mass origins (e.g., Sahara or marine boundary layer) prevailed. Elevated concentrations were measured in the field campaigns of 2016, which might be due to enhanced influence from Saharan dust and marine boundary layer air arriving at the JFJ. The upper limit of INP concentrations in the background FT is supported by measurements performed at similar conditions, but at different locations in the FT, where we find INP concentrations to be below 13/stdL most of the time. ©2018. The Authors."
"56255280300;21934985600;54793961000;","Automated segmentation of leaves from deciduous trees in terrestrial laser scanning point clouds",2018,"10.1109/LGRS.2018.2841429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048642041&doi=10.1109%2fLGRS.2018.2841429&partnerID=40&md5=32eaa6369c2a56dfe2c4730899bd1e82","Recent improvements in topographic LiDAR technology allow the detailed characterization of individual trees at both branch and leaf scale, providing more accurate information to support phenological and ecological research. However, an effective methodology to map single leaves in 3-D is still missing. This letter presents a point cloud segmentation approach for single leaf detection and the derivation of selected morphological features (i.e., leaf area (LA), maximal leaf length, width, and slope) using terrestrial laser scanning. The developed approach consists of 1) filtering noise points; 2) region growing segmentation; 3) separating leaf and nonleaf segments; and 4) calculating leaf-morphological features. For the evaluation of the workflow, two deciduous trees were scanned. A Selection of leaves of the specified trees was randomly harvested during the field campaign for comparison. A qualitative comparison analysis was carried out between the area of the harvested leaves and the leaf area (LA) derived from 3-D point cloud segmentation. In addition, a sensitivity analysis investigated the effect of the segmentation parameterization. This step revealed that the proposed segmentation algorithm is robust when using an optimum subset of parameter values. However, the determination of leaf outlines is limited due to the orientation of leaves to the scanner, shadow effects, and the inhomogeneity of the point cloud. The results underline the potential of region growing segmentation of point clouds for providing accurate information on single leaves and vegetation structure in more detail. This facilitates improvements in applications such as estimating water balance, biomass, or leaf area (LA) index. © 2018 IEEE."
"6506848120;55469200300;57188729343;15726759700;56499447000;7005960178;7004740995;57199858392;55966258500;6602914876;7004944088;6506126751;35595682100;8363388700;7005078521;24587715900;7402838215;","Ice particle sampling from aircraft - Influence of the probing position on the ice water content",2018,"10.5194/amt-11-4015-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049828978&doi=10.5194%2famt-11-4015-2018&partnerID=40&md5=9324e7fbf67552521418904226d29565","The ice water content (IWC) of cirrus clouds is an essential parameter determining their radiative properties and thus is important for climate simulations. Therefore, for a reliable measurement of IWC on board research aircraft, it is important to carefully design the ice crystal sampling and measuring devices. During the ML-CIRRUS field campaign in 2014 with the German Gulfstream GV HALO (High Altitude and Long Range Research Aircraft), IWC was recorded by three closed-path total water together with one gas-phase water instrument. The hygrometers were supplied by inlets mounted on the roof of the aircraft fuselage. Simultaneously, the IWC is determined by a cloud particle spectrometer attached under an aircraft wing. Two more examples of simultaneous IWC measurements by hygrometers and cloud spectrometers are presented, but the inlets of the hygrometers were mounted at the fuselage side (M-55 Geophysica, StratoClim campaign 2017) and bottom (NASA WB57, MacPex campaign 2011). This combination of instruments and inlet positions provides the opportunity to experimentally study the influence of the ice particle sampling position on the IWC with the approach of comparative measurements. As expected from theory and shown by computational fluid dynamics (CFD) calculations, we found that the IWCs provided by the roof inlets deviate from those measured under the aircraft wing. As a result of the inlet position in the shadow zone behind the aircraft cockpit, ice particle populations with mean mass sizes larger than about 25 μm radius are subject to losses, which lead to strongly underestimated IWCs. On the other hand, cloud populations with mean mass sizes smaller than about 12 μm are dominated by particle enrichment and thus overestimated IWCs. In the range of mean mass sizes between 12 and 25 μm, both enrichment and losses of ice crystals can occur, depending on whether the ice crystal mass peak of the size distribution - in these cases bimodal - is on the smaller or larger mass mode. The resulting deviations of the IWC reach factors of up to 10 or even more for losses as well as for enrichment. Since the mean mass size of ice crystals increases with temperature, losses are more pronounced at higher temperatures, while at lower temperatures IWC is more affected by enrichment. In contrast, in the cases where the hygrometer inlets were mounted at the fuselage side or bottom, the agreement of IWCs is most frequently within a factor of 2.5 or better - due to less disturbed ice particle sampling, as expected from theory - independently of the mean ice crystal sizes. The rather large scatter between IWC measurements reflects, for example, cirrus cloud inhomogeneities and instrument uncertainties as well as slight sampling biases which might also occur on the side or bottom of the fuselage and under the wing. However, this scatter is in the range of other studies and represent the current best possible IWC recording on fast-flying aircraft. © 2018 Author(s)."
"57193063351;57203052406;7003842561;57148719700;56251513200;7403019231;","Impact of urban aerosol properties on cloud condensation nuclei (CCN) activity during the KORUS-AQ field campaign",2018,"10.1016/j.atmosenv.2018.05.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047178508&doi=10.1016%2fj.atmosenv.2018.05.019&partnerID=40&md5=6ff6aa9db110638c6eabf8a8fb577dbf","Ground measurements of physical, chemical and hygroscopic properties of aerosols were made at the Olympic Park, Seoul, as part of the KORea-United States Air Quality study (KORUS-AQ) campaign in May–June 2016. The average number concentrations of aerosols larger than 10 nm in diameter and cloud condensation nuclei (CCN) at 0.6% supersaturation (S) were 10800 cm−3 and 3400 cm−3, respectively. The average geometric mean diameter (Dg) was 44 nm, and size-resolved aerosol hygroscopicity (κ) from HTDMA ranged from 0.11 to 0.24 for particle diameters in the range of 30–150 nm. Aerosols were classified into three types based on mixing state and hygroscopic growth factor (GF): Type 1 (externally mixed aerosol), Type 2 (Internally mixed and growth aerosol) and Type 3 (internally mixed and non-growth aerosol). These three aerosol types showed distinct diurnal patterns. The difference in physical and chemical properties of aerosols for different air mass sources crucially impacted aerosol hygroscopicity. Using the external mixture assumption with measured hygroscopicity data improved the results of CCN prediction compared to those from the simple internal mixture assumption because externally mixed aerosols comprised a significant portion of aerosols in this urban area. Moreover, the simple assumption of aerosol size distribution with a fixed chemical composition sufficiently explained more than 50 percent of the variation of CCN number concentrations, although the information of chemical composition was still meaningful. Overall, the measured data showed consistency with Megacity Air Pollution Studies (MAPS-Seoul) campaign held during May–June 2015, implying that these results may represent urban aerosols in spring/summer in the Korean Peninsula. © 2018 Elsevier Ltd"
"41662112800;36867650000;34972803800;7003408439;","The diurnal variability of precipitating cloud populations during DYNAMO",2018,"10.1175/JAS-D-17-0312.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047062327&doi=10.1175%2fJAS-D-17-0312.1&partnerID=40&md5=1b65cef306718a0b78c7976c19a15be0","This study uses high-resolution rainfall estimates from the S-Polka radar during the DYNAMO field campaign to examine variability of the diurnal cycle of rainfall associated with MJO convection over the Indian Ocean. Two types of diurnal rainfall peaks were found: 1) a late afternoon rainfall peak associated with the diurnal peak in sea surface temperatures (SSTs) and surface fluxes and 2) an early to late morning rainfall peak associated with increased low-tropospheric moisture. Both peaks appear during the MJO suppressed phase, which tends to have stronger SST warming in the afternoon, while the morning peak is dominant during the MJO enhanced phase. The morning peak occurs on average at 0000-0300 LST during the MJO suppressed phase, while it is delayed until 0400-0800 LST during the MJO enhanced phase. This delay partly results from an increased upscale growth of deep convection to broader stratiform rain regions during the MJO enhanced phase. During the MJO suppressed phase, rainfall is dominated by deep and isolated convective cells that are short-lived and peak in association with either the afternoon SST warming or nocturnal moisture increase. This study demonstrates that knowledge of the evolution of cloud and rain types is critical to explaining the diurnal cycle of rainfall and its variability. Some insights into the role of the complex interactions between radiation, moisture, and clouds in driving the diurnal cycle of rainfall are also discussed. © 2018 American Meteorological Society."
"56088730900;57190729385;57193882808;7003606341;","Anisotropy of Observed and Simulated Turbulence in Marine Stratocumulus",2018,"10.1002/2017MS001140","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042375686&doi=10.1002%2f2017MS001140&partnerID=40&md5=d1563c32a9cbf5e0356e71460288d9e0","Anisotropy of turbulence near the top of the stratocumulus-topped boundary layer (STBL) is studied using large-eddy simulation (LES) and measurements from the POST and DYCOMS-II field campaigns. Focusing on turbulence ~ m below the cloud top, we see remarkable similarity between daytime and nocturnal flight data covering different inversion strengths and free-tropospheric conditions. With λ denoting wavelength and Zt cloud-top height, we find that turbulence at λ/Zt ≃0.01 is weakly dominated by horizontal fluctuations, while turbulence at λ/Zt002E1 becomes strongly dominated by horizontal fluctuations. Between are scales at which vertical fluctuations dominate. Typical-resolution LES of the STBL (based on POST flight 13 and DYCOMS-II flight 1) captures observed characteristics of below-cloud-top turbulence reasonably well. However, using a fixed vertical grid spacing of 5 m, decreasing the horizontal grid spacing and increasing the subgrid-scale mixing length leads to increased dominance of vertical fluctuations, increased entrainment velocity, and decreased liquid water path. Our analysis supports the notion that entrainment parameterizations (e.g., in climate models) could potentially be improved by accounting more accurately for anisotropic deformation of turbulence in the cloud-top region. While LES has the potential to facilitate improved understanding of anisotropic cloud-top turbulence, sensitivity to grid spacing, grid-box aspect ratio, and subgrid-scale model needs to be addressed. © 2018. The Authors."
"55315290600;6603926727;57210373496;15318942300;","Microphysical characteristics of convective clouds over ocean and land from aircraft observations",2017,"10.1016/j.atmosres.2017.05.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019945091&doi=10.1016%2fj.atmosres.2017.05.011&partnerID=40&md5=61806f3a7fc3c1ca4d1b4d269a2273cd","The Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) is a field campaign conducted in India with an instrumented research aircraft. On 29 October 2010, a cyclonic circulation over the Bay of Bengal persisted throughout the day. A special mission was conducted over the Bay of Bengal on this day with the objective of characterizing marine and continental clouds on the same day and finding contrasting/similar signatures of their microphysical properties. The research aircraft sampled growing convective clouds over the ocean and over land. High concentrations of aerosol and cloud condensation nuclei (CCN) were observed over land compared to ocean. Over ocean, higher liquid water content (LWC) and lower cloud droplet number concentrations (Nc) were observed, and droplets reached the threshold of precipitation initiation at lower cloud depths. Over land, clouds contained lower LWC and higher Nc, hence droplets did not reach the threshold of precipitation initiation at a warm temperature as in ocean clouds. Over the ocean larger droplets or drizzle were observed at lower cloud depth than over land. The maximum LWC was found to be very similar at higher altitudes. The convective clouds over land were modified by pollution aerosol with contrasting microphysical properties to those over the ocean. © 2017"
"57183823300;55763471100;","Physical controls on frost events in the central Andes of Peru using in situ observations and energy flux models",2017,"10.1016/j.agrformet.2017.02.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015710670&doi=10.1016%2fj.agrformet.2017.02.019&partnerID=40&md5=7ae8355a964541ee84e5a7e3ab1c61d3","Radiative frosts are a major hazard to agriculture in the tropical Andes of Peru, but there are very few studies of their physical controls. In this study we focus on identifying and approximately estimating the effect that physical variables have on both the downward surface longwave flux (LW↓) and the minimum temperature (Tmin). Through a combination of case studies and statistical analysis of in situ data in the IGP Huancayo Observatory, we found that low cloud cover (CC), surface specific humidity (q), and soil moisture are key factors controlling the day-to-day variability of Tmin, which is more pronounced in the dry/cool season. We found that all frost days had q &lt; 7 g/kg in the dry season and q &lt; 5 g/kg in the wet season, although it should be emphasized that q covaries with CC and soil moisture. We successfully validated a numerical soil heat diffusion model with data from a field campaign in July 2010 and we used it, together with a radiative transfer model, to estimate the sensitivities of Tmin and LW↓ to atmospheric and soil variables. With these results we estimated the partial contributions of these variables to the overall day-to-day variability in Tmin and LW↓. We found that low cloud cover is the dominant factor, although specific humidity has a comparable role in the wet season. Lack of information on the cloud liquid water path is an important source of uncertainty. Enhanced soil moisture has a strong mitigating effect on frosts, although strong variability of soil moisture in the wet season could contribute substantially to the development of frosts. © 2017 Elsevier B.V."
"57192063986;23048575400;7103204204;6603382350;56363987000;57190209035;","Directional, horizontal inhomogeneities of cloud optical thickness fields retrieved from ground-based and airbornespectral imaging",2017,"10.5194/acp-17-2359-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012993368&doi=10.5194%2facp-17-2359-2017&partnerID=40&md5=8a2df399876cf12c798c22edf21d99e2","Clouds exhibit distinct horizontal inhomogeneities of their optical and microphysical properties, which complicate their realistic representation in weather and climate models. In order to investigate the horizontal structure of cloud inhomogeneities, 2-D horizontal fields of optical thickness (τ) of subtropical cirrus and Arctic stratus are investigated with a spatial resolution of less than 10m. The 2-D τ-fields are derived from (a) downward (transmitted) solar spectral radiance measurements from the ground beneath four subtropical cirrus and (b) upward (reflected) radiances measured from aircraft above 10 Arctic stratus. The data were collected during two field campaigns: (a) Clouds, Aerosol, Radiation, and tuRbulence in the trade wind regime over BArbados (CARRIBA) and (b) VERtical Distribution of Ice in Arctic clouds (VERDI). One-dimensional and 2-D autocorrelation functions, as well as power spectral densities, are derived from the retrieved τ-fields. The typical spatial scale of cloud inhomogeneities is quantified for each cloud case. Similarly, the scales at which 3-D radiative effects influence the radiance field are identified. In most of the investigated cloud cases considerable cloud inhomogeneities with a prevailing directional structure are found. In these cases, the cloud inhomogeneities favour a specific horizontal direction, while across this direction the cloud is of homogeneous character. The investigations reveal that it is not sufficient to quantify horizontal cloud inhomogeneities using 1-D inhomogeneity parameters; 2-D parameters are necessary. © 2017 The Author(s)."
"7801680684;","Analysis of geomorphic changes and quantification of sediment budgets of a small Arctic valley with the application of repeat TLS surveys",2017,"10.1127/zfg_suppl/2017/0330","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029715505&doi=10.1127%2fzfg_suppl%2f2017%2f0330&partnerID=40&md5=3ea3e199daa8e6ac7cb06e04beca16ed","The article reports the application of high-resolution repeat Terrestrial Laser Scanning (TLS) surveys in the assessment of erosion and deposition volumes in the valley of the Tyvjobekken Creek (NW part of the Wedel-Jarlsberg Land, Spitsbergen, and Svalbard). High resolution (&gt; 300 points m- 2) data was obtained across the estuarial part of the valley with an area of 92,631 m2 during the culmination of meltwater seasons 2010 and 2013. The field works involved the application of a Leica Scan Station C10, and Real Time Kinematic Global Positioning System (GPS RTK). A complex survey was carried out from 5 (2010) and 24 (2013) interrelated measurement sites. Three square-shaped test areas (of 10,000 m2 each) located in the central and lower parts of the valley were designated for the evaluation of medium-scale morphological transformations. 3D scanning at each of the sites permitted obtaining a point cloud of ~5 million points (M pt.). The resulting clouds of data of 25.5 and 155.5 M pt (respectively) were used for the development of digital elevation models (DEMs) of the river valley with a length of more than 0.6 km and width of up to 0.2 km for both of the field campaigns (in 2013 1.2 km and 0.45 km, respectively). TLS-based difference digital elevation models (DoD) were compared. High definition TLS surveys showed great registration accuracy 0.009 m during field campaign 2010 and better than 0.02 m in 2013. Changes in morphology were identified throughout a 3-year period. 55 % of the study area was eroded (51,339 m2), particularly in the lower parts of the valley floor (gorge section), south slope, and alluvial fan. This resulted in the removal of 6,691 m3 of sediment volume. Deposition concerned 45 % of the study area - 5,207 m3 of sediment volume respectively. The subtraction of consecutive DEMs of the test areas revealed downstream spatial and volumetric differentiation: from deposition predominance in the central part of the gorge (65 %, 6,475 m2, 128.6 m3), through erosion predominance in the mouth part of the gorge (60 %, 6,021 m2, 196.6 m3), to the dominance of erosion in the central part of the alluvial fan (98 %, 9,534 m2, 601.2 m3). © 2017 Gebrüder Borntraeger Verlagsbuchhandlung, Stuttgart, Germany."
"57190667254;7410041005;7005729142;7403331283;","Characteristics of vertical air motion in isolated convective clouds",2016,"10.5194/acp-16-10159-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982112086&doi=10.5194%2facp-16-10159-2016&partnerID=40&md5=de4d85b6d1003eb4d62ba878d1191727","The vertical velocity and air mass flux in isolated convective clouds are statistically analyzed using aircraft in situ data collected from three field campaigns: High-Plains Cumulus (HiCu) conducted over the midlatitude High Plains, COnvective Precipitation Experiment (COPE) conducted in a midlatitude coastal area, and Ice in Clouds Experiment-Tropical (ICE-T) conducted over a tropical ocean. The results show that small-scale updrafts and downdrafts (lt;500 m in diameter) are frequently observed in the three field campaigns, and they make important contributions to the total air mass flux. The probability density functions (PDFs) and profiles of the observed vertical velocity are provided. The PDFs are exponentially distributed. The updrafts generally strengthen with height. Relatively strong updrafts (&amp;gt; 20 m s-1) were sampled in COPE and ICE-T. The observed downdrafts are stronger in HiCu and COPE than in ICE-T. The PDFs of the air mass flux are exponentially distributed as well. The observed maximum air mass flux in updrafts is of the order 104 kg -1 s-1. The observed air mass flux in the downdrafts is typically a few times smaller in magnitude than that in the updrafts. Since this study only deals with isolated convective clouds, and there are many limitations and sampling issues in aircraft in situ measurements, more observations are needed to better explore the vertical air motion in convective clouds. © 2016 Author(s)."
"12762440500;14048744800;25959502500;36020828900;8722004900;56252813600;25959487500;8517509300;29367493100;25959690600;","A review of advances in lightning observations during the past decade in Guangdong, China",2016,"10.1007/s13351-016-6928-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992731349&doi=10.1007%2fs13351-016-6928-7&partnerID=40&md5=f7629af20dbe1399d2020e3ef1d0754c","This paper reviews recent advances in understanding the physical processes of artificially triggered lightning and natural lightning as well as the progress in testing lightning protection technologies, based on a series of lightning field campaigns jointly conducted by the Chinese Academy of Meteorological Sciences and Guangdong Meteorological Bureau since 2006. During the decade-long series of lightning field experiments, the technology of rocket-wire artificially triggered lightning has been improved, and has successfully triggered 94 lightning flashes. Through direct lightning current waveform measurements, an average return stroke peak current of 16 kA was obtained. The phenomenon that the downward leader connects to the lateral surface of the upward leader in the attachment process was discovered, and the speed of the upward leader during the connection process being significantly greater than that of the downward leader was revealed. The characteristics of several return strokes in cloud-to-ground lighting have also been unveiled, and the mechanism causing damage to lightning protection devices (i.e., ground potential rise within the rated current) was established. The performance of three lightning monitoring systems in Guangdong Province has also been quantitatively assessed. © 2016, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"55875842200;7409080503;8839875600;","Response of marine boundary layer cloud properties to aerosol perturbations associated with meteorological conditions from the 19-month AMF-Azores campaign",2016,"10.1175/JAS-D-15-0364.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994081865&doi=10.1175%2fJAS-D-15-0364.1&partnerID=40&md5=e3e5d7ef715fd196fdd3e5ff3e8ee8d7","This study investigates the response of marine boundary layer (MBL) cloud properties to aerosol loading by accounting for the contributions of large-scale dynamic and thermodynamic conditions and quantifies the first indirect effect (FIE). It makes use of 19-month measurements of aerosols, clouds, and meteorology acquired during theAtmospheric Radiation Measurement Mobile Facility field campaign over the Azores. Cloud droplet number concentrations Nc and cloud optical depth (COD) significantly increased with increasing aerosol number concentration Na. Cloud droplet effective radius (DER) significantly decreased with increasing Na. The correlations between cloud microphysical properties [Nc, liquid water path (LWP), and DER] and Na were stronger undermore stable conditions. The correlations between Nc, LWP, DER, and Na were stronger under ascendingmotion conditions, while the correlation between COD and Na was stronger under descending-motion conditions. The magnitude and corresponding uncertainty of the FIE (=[-∂ ln(DER)/∂ ln(Na)] at constant LWP) ranged from 0.060 ± 0.022 to 0.101 ± 0.006 depending on the different LWP values. Under more stable conditions, cloud-base heights were generally lower than those under less stable conditions. This enabled a more effective interaction with aerosols, resulting in a larger value for the FIE. However, the dependence of the response of cloud properties to aerosol perturbations on stability varied according to whether ground- or satellite-based DER retrievals were used. The magnitude of the FIE had a larger variation with changing LWP under ascending-motion conditions and tended to be higher under ascending-motion conditions for clouds with low LWP and under descending-motion conditions for clouds with highLWP.Acontrasting dependence of FIE on atmospheric stability estimated fromthe surface and satellite cloud properties retrievals reported in this study underscores the importance of assessing all-level properties of clouds in aerosol-cloud interaction studies. © 2016 American Meteorological Society."
"36701299900;6602913723;7801612614;6603768370;6505856601;57206307062;24401929100;6602715030;","Statistical analysis of storm electrical discharges reconstituted from a lightning mapping system, a lightning location system, and an acoustic array",2016,"10.1002/2015JD023745","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964597637&doi=10.1002%2f2015JD023745&partnerID=40&md5=cdf5b580a2f5082274416fe98c982117","In the framework of the European Hydrological Cycle in the Mediterranean Experiment project, a field campaign devoted to the study of electrical activity during storms took place in the south of France in 2012. An acoustic station composed of four microphones and four microbarometers was deployed within the coverage of a Lightning Mapping Array network. On the 26 October 2012, a thunderstorm passed just over the acoustic station. Fifty-six natural thunder events, due to cloud-to-ground and intracloud flashes, were recorded. This paper studies the acoustic reconstruction, in the low frequency range from 1 to 40 Hz, of the recorded flashes and their comparison with detections from electromagnetic networks. Concurrent detections from the European Cooperation for Lightning Detection lightning location system were also used. Some case studies show clearly that acoustic signal from thunder comes from the return stroke but also from the horizontal discharges which occur inside the clouds. The huge amount of observation data leads to a statistical analysis of lightning discharges acoustically recorded. Especially, the distributions of altitudes of reconstructed acoustic detections are explored in detail. The impact of the distance to the source on these distributions is established. The capacity of the acoustic method to describe precisely the lower part of nearby cloud-to-ground discharges, where the Lightning Mapping Array network is not effective, is also highlighted. © 2016. American Geophysical Union. All Rights Reserved."
"6701718281;7004474392;6603371044;55559573300;","Quantitative sensitivity analysis of physical parameterizations for cases of deep convection in the NASA GEOS-5",2016,"10.1175/JCLI-D-15-0250.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957806825&doi=10.1175%2fJCLI-D-15-0250.1&partnerID=40&md5=842c4303aef7d4fff317c224f2da286f","Parameterization of processes that occur on length scales too small to resolve on a computational grid is a major source of uncertainty in global climate models. This study investigates the relative importance of a number of parameters used in the Goddard Earth Observing System Model, version 5 (GEOS-5), atmospheric general circulation model, focusing on cloud, convection, and boundary layer parameterizations. Latin hypercube sampling is used to generate a few hundred sets of 19 candidate physics parameters, which are subsequently used to generate ensembles of single-column model realizations of cloud content, precipitation, and radiative fluxes for four different field campaigns. A Gaussian process model is then used to create a computationally inexpensive emulator for the simulation code that can be used to determine a measure of relative parameter sensitivity by sampling the response surface for a very large number of input parameter sets. Parameter sensitivities are computed for different geographic locations and seasons to determine whether the intrinsic sensitivity of the model parameterizations changes with season and location. The results indicate the same subset of parameters collectively control the model output across all experiments, independent of changes in the environment. These are the threshold relative humidity for cloud formation, the ice fall speeds, convective and large-scale autoconversion, deep convection relaxation time scale, maximum convective updraft diameter, and minimum ice effective radius. However, there are differences in the degree of parameter sensitivity between continental and tropical convective cases, as well as systematic changes in the degree of parameter influence and parameter-parameter interaction. © 2016 American Meteorological Society."
"7004057920;54783781000;36628712500;56036132800;8343401100;57201726470;7006675203;6603712566;","A high-resolution oxygen A-band spectrometer (HABS) and its radiation closure",2014,"10.5194/amt-7-1711-2014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84902461536&doi=10.5194%2famt-7-1711-2014&partnerID=40&md5=1de507683c9dd1434fc9f32cf26d89d0","Various studies indicate that high-resolution oxygen A-band spectrum has the capability to retrieve the vertical profiles of aerosol and cloud properties. To improve the understanding of oxygen A-band inversions and utility, we developed a high-resolution oxygen A-band spectrometer (HABS), and deployed it at Howard University Beltsville site during the NASA Discover Air-Quality Field Campaign in July, 2011. By using a single telescope, the HABS instrument measures the direct solar and the zenith diffuse radiation subsequently. HABS exhibits excellent performance: stable spectral response ratio, high signal-to-noise ratio (SNR), high-spectrum resolution (0.016 nm), and high out-of-band rejection (10-5). For the spectral retrievals of HABS measurements, a simulator is developed by combining a discrete ordinates radiative transfer code (DISORT) with the High Resolution Transmission (HITRAN) database HITRAN2008. The simulator uses a double-k approach to reduce the computational cost. The HABS-measured spectra are consistent with the related simulated spectra. For direct-beam spectra, the discrepancies between measurements and simulations, indicated by confidence intervals (95%) of relative difference, are (-0.06, 0.05) and (-0.08, 0.09) for solar zenith angles of 27 and 72°, respectively. For zenith diffuse spectra, the related discrepancies between measurements and simulations are (-0.06, 0.05) and (-0.08, 0.07) for solar zenith angles of 27 and 72°, respectively. The main discrepancies between measurements and simulations occur at or near the strong oxygen absorption line centers. They are mainly due to two kinds of causes: (1) measurement errors associated with the noise/spikes of HABS-measured spectra, as a result of combined effects of weak signal, low SNR, and errors in wavelength registration; (2) modeling errors in the simulation, including the error of model parameters setting (e.g., oxygen absorption line parameters, vertical profiles of temperature and pressure) and the lack of treatment of the rotational Raman scattering. The high-resolution oxygen A-band measurements from HABS can constrain the active radar retrievals for more accurate cloud optical properties (e.g., cloud optical depth, effective radius), particularly for multi-layer clouds and for mixed-phase clouds. © 2014 Author(s) CC Attribution 3.0 License."
"55533428600;7402900768;6701873414;44261758800;7401626699;","Probabilistic forecasting for isolated thunderstorms using a genetic algorithm: The DC3 campaign",2014,"10.1002/2013JD020195","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84893969133&doi=10.1002%2f2013JD020195&partnerID=40&md5=c10eb83324d251d2017a54e1ff7c1f37","Researchers on the Deep Convective Clouds and Chemistry (DC3) field campaign in summer 2012 sought airborne in situ measurements of isolated thunderstorms in three different study regions: northeast Colorado, north Alabama, and a larger region extending from central Oklahoma through northwest Texas. Experiment objectives required thunderstorms that met four criteria. To sample thunderstorm outflow, storms had to be large enough to transport boundary-layer air to the upper troposphere and have a lifetime long enough to produce a large anvil. The storms had to be small enough to sample safely and isolated enough that experimenters could distinguish the impact of a particular thunderstorm from other convection in the area. To aid in the optimization of daily flight decisions, an algorithmic forecasting system was developed that produced probabilistic forecasts of suitable flight conditions for each of the three regions. Atmospheric variables forecast by a high-resolution numerical weather prediction model for each region were converted to probabilistic forecasts of suitable conditions using fuzzy logic trapezoids, which quantified the favorability of each variable. In parallel, the trapezoid parameters were tuned using a genetic algorithm and the favorability values of each of the atmospheric variables were weighted using a logistic regression. Results indicate that the automated forecasting system shows predictive skill over climatology in each region, with Brier skill scores of 16% to 45%. Averaged over all regions, the automated forecasting system showed a Brier skill score of 32%, compared to the 24% Brier skill score shown by human forecast teams. © 2013. American Geophysical Union. All rights reserved."
"35264934000;7004885872;7101846027;","Microphysical imprint of entrainment in warm cumulus",2013,"10.3402/tellusb.v65i0.19922","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907422934&doi=10.3402%2ftellusb.v65i0.19922&partnerID=40&md5=28b1ce79b9c6fbabf3630b02381ff3a7","We analyse the cloud microphysical response to entrainment mixing in warm cumulus clouds observed from the CIRPAS Twin Otter during the GoMACCS field campaign near Houston, Texas, in summer 2006. Cloud drop size distributions and cloud liquid water contents from the Artium Flight phase-Doppler interferometer in conjunction with meteorological observations are used to investigate the degree to which inhomogeneous versus homogeneous mixing is preferred as a function of height above cloud base, distance from cloud edge and aerosol concentration. Using four complete days of data with 101 cloud penetrations (minimum 300m in length), we find that inhomogeneous mixing primarily explains liquid water variability in these clouds. Furthermore, we show that there is a tendency for mixing to be more homogeneous towards the cloud top, which we attribute to the combination of increased turbulent kinetic energy and cloud drop size with altitude which together cause the Damköhler number to increase by a factor of between 10 and 30 from cloud base to cloud top. We also find that cloud edges appear to be air from cloud centres that have been diluted solely through inhomogeneous mixing. Theory predicts the potential for aerosol to affect mixing type via changes in drop size over the range of aerosol concentrations experienced (moderately polluted rural sites to highly polluted urban sites). However, the observations, while consistent with this hypothesis, do not show a statistically significant effect of aerosol on mixing type. © 2013 J. D. Small et al."
"57213056522;7801634218;","Progress on predicting the breadth of droplet size distributions observed in small cumuli",2011,"10.1175/JAS-D-11-0153.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84855853763&doi=10.1175%2fJAS-D-11-0153.1&partnerID=40&md5=7a6f1af358ad1dbce5a744b04378db57","A modeling framework representing variations in droplet growth by condensation, resulting from different saturation histories experienced as a result of entrainment and mixing, is used to predict the breadth of droplet size distributions observed at different altitudes within trade wind cumuli observed on 10 December 2004 during the Rain in Cumulus over the Ocean (RICO) field campaign. The predicted droplet size distributions are as broad as those observed, contain similar numbers of droplets, and are generally in better agreement with the observations when some degree of inhomogeneous droplet evaporation is considered, allowing activation of newly entrained cloud condensation nuclei. The variability of the droplet growth histories, resulting primarily from entrainment, appears to explain the magnitude of the observed droplet size distribution widths, without representation of other broadening mechanisms. Additional work is needed, however, as the predicted mean droplet diameter is too large relative to the observations and likely results from the model resolution limiting dilution of the simulated cloud. © 2011 American Meteorological Society."
"7403364008;25953950400;","A method for forecasting cloud condensation nuclei using predictions of aerosol physical and chemical properties from WRF/Chem",2011,"10.1175/2011JAMC2644.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960388815&doi=10.1175%2f2011JAMC2644.1&partnerID=40&md5=85dc032e888f8ee1b1923069762b2ff4","Model investigations of aerosol-cloud interactions across spatial scales are necessary to advance basic understanding of aerosol impacts on climate and the hydrological cycle. Yet these interactions are complex, involving numerous physical and chemical processes. Models capable of combining aerosol dynamics and chemistry with detailed cloud microphysics are recent developments. In this study, predictions of aerosol characteristics from the Weather Research and Forecasting Model with Chemistry (WRF/Chem) are integrated into the Regional Atmospheric Modeling System microphysics package to form the basis of a coupled model that is capable of predicting the evolution of atmospheric aerosols from gas-phase emissions to droplet activation. The new integrated system is evaluated against measurements of cloud condensation nuclei (CCN) from a land-based field campaign and an aircraft-based field campaign in Colorado. The model results show the ability to capture vertical variations in CCN number concentration within an anthropogenic pollution plume. In a remote continental location the model-forecast CCN number concentration exhibits a positive bias that is attributable in part to an overprediction of the aerosol hygroscopicity that results from an underprediction in the organic aerosol mass fraction. In general, the new system for predicting CCN from forecast aerosol fields improves on the existing scheme in which aerosol quantities were user prescribed. © 2011 American Meteorological Society."
"55262957100;7402469637;16230028100;15922857300;16445019500;15726586900;7004048062;8506639100;","Cloud-top height variability associated with equatorial Kelvin waves in the tropical tropopause layer during the Mirai Indian Ocean cruise for the Study of the MJO-convection onset (MISMO) campaign",2010,"10.2151/sola.2010-025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954780973&doi=10.2151%2fsola.2010-025&partnerID=40&md5=d42db0e1178119139d90bf9b07b013b7","Cloud-top height (CTH) variability in the tropical tropopause layer (TTL) in association with equatorial Kelvin waves is investigated using a new CTH dataset based on MTSAT-1R geostationary satellite measurements with a statistical look-up table constructed based on CloudSat measurements. We focus on a case in the tropical Indian Ocean during October-December 2006, when shipboard radiosonde, TTL water vapor, and 95-GHz cloud radar measurements were taken during the Mirai Indian Ocean cruise for the Study of the MJO-convection Onset (MISMO) field campaign. At 10-15 km, the satellite-based CTH data agree well with the radar echo top heights from shipboard radar reflectivity data. During the MISMO campaign, cloud frequency was suppressed in the warm phase of equatorial Kelvin waves propagating in the TTL. The suppressed-cloud region moves eastward to the western Pacific together with Kelvin waves. We found that changes in CTH occurrence frequency over the vessel in association with Kelvin waves are much greater than those associated with the diurnal cycle. It is expected that the phase of equatorial Kelvin waves is important for the intraseasonal variabilities of both the radiative budget of the tropical atmosphere and water vapor transport in the TTL. © 2010, the Meteorological Society of Japan."
"57200241494;24315205000;7003548068;","A climatological study of sea breeze clouds in the Southeast of the Iberian Peninsula (Alicante, Spain)",2009,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-60149095701&partnerID=40&md5=d22f7ca948afee98846d48f03dbc285d","Sea breezes blow under anticyclonic weather types, weak surface pressure gradients, intense solar radiation and relatively cloud-free skies. Generally, total cloud cover must be less than 4/8 in order to cause a thermal and pressure difference between land and sea air which allows the development of this local wind circulation. However, many numerical and observational studies have analyzed the ability of sea breezes to generate clouds in the convective internal boundary layer and in the sea breeze convergence zone. Accordingly, the aim of this study is to statistically analyze the impact of sea breezes on cloud types in the convective internal boundary layer and in the sea breeze convergence zone. The study area is located in the southeast of the Iberian Peninsula (province of Alicante, Spain) and the survey corresponds to a 6-yr study period (2000-2005). This climatological study is mainly based on surface cloud observations at the Alicante-Ciudad Jardin station (central coastal plain) and on an extensive cloud observation field campaign at the Villena-Ciudad station (Prebetic mountain ranges) over a 3-yr study period (2003-2005). The results confirm the hypothesis that the effect of sea breezes on cloud genera is to increase the frequency of low (Stratus) and convective (Cumulus) clouds. Sea breezes trigger the formation of thunderstorm clouds (Cumulonimbus) at the sea breeze convergence zone, which also have a secondary impact on high-level (Cirrus, Cirrocumulus, Cirrostratus), medium-level (Altostratus, Altocumulus) and low-level clouds (Stratus, Stratocumulus, Nimbostratus) associated with the Cumulonimbus clouds (e.g., Cumulonimbus anvil)."
"7005668309;16185051500;","An aerosol model and aerosol-induced changes in the clear-sky albedo off the east coast of the United States",2001,"10.1029/2001JD900025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034951364&doi=10.1029%2f2001JD900025&partnerID=40&md5=18bc9ed50be17fecc8e025d1da84a36c","Changes in the cloud-free albedo of the Earth, and therefore direct aerosol radiative forcing, due to aerosol can be parameterized as a function of one extensive quantity that depends on the amount of aerosol present (e.g., the aerosol optical depth, τ) and two intensive quantities that depend on the internal characteristics of the aerosol (the aerosol single-scattering albedo, ωo, and the aerosol asymmetry parameter, g). Airborne measurements of the dry aerosol scattering and absorption coefficients and dry particle size distributions made aboard the University of Washington's research aircraft during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) field campaign off the east coast of the United States in July 1996 are used in conjunction with measurements of the effects of humidity on aerosol light scattering to determine an optically equivalent model for the physical and optical properties of the ambient aerosol. This model is validated and used to derive values of ωo and g for the ambient (wet) aerosol. The average and standard deviation of the column-mean, ambient values of ωo and g at a wavelength of 550 nm, determined from 12 vertical profiles, are 0.958 ± 0.050 and 0.703 ± 0.092, respectively. A pronounced increase in g with increasing relative humidity is observed. Using the aerosol model, the mean instantaneous change in the local albedo induced by the aerosol is found to be 0.027 ± 0.018 at a wavelength of 550 nm (compared to an albedo of about 0.05 for the ocean). Copyright 2001 by the American Geophysical Union."
"7003728829;7103129962;6603603545;7202154370;7006577245;","Boundaries and internal structure of mixed phase clouds as deduced from ground-based 95-GHz radar and airborne lidar measurements",2000,"10.1016/S1464-1909(00)00121-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033772580&doi=10.1016%2fS1464-1909%2800%2900121-0&partnerID=40&md5=6f7c712d58e9475f4c345eea7d525229","Knowledge on the occurrence of multiple cloud layers, the heights of their boundaries, their internal structure and phase is important for an accurate determination of radiative fluxes through the atmosphere. Multi-layer mixed phase clouds have simultaneously been profiled with a ground-based 95-GHz radar and Ne:YAG based airborne lidars. Due to their different attenuation and sensitivity to particle size and phase these instruments provide complementary information of cloud boundaries and cloud structure. Case studies from a field campaign over Southern UK are presented. In one case a narrow altostratus layer of mainly spherical, liquid particles was embedded in an ice cloud of larger vertical extent. The liquid layer was resolved in detail by the lidar but did not appear distinguishably in the radar profile, which was much more sensitive to the ice particles. Fallstreaks below the cloud base show a signature in the radar signals only. In another case the lidar beam was blocked in the upper part of a mid-level cloud layer with band like structure, while this cloud hardly appeared in the radar reflectivity which instead was dominated by another band 1 km below. Both instruments detected nearly the same cloud boundaries and structures when the liquid layer disappeared and an optically thin ice cloud remained. This study clearly reveals the tremendous information gain by a synergetic use of radar and lidar for cloud profiling. (C) 2000 Elsevier Science Ltd. All rights reserved."
"56724696200;36724322000;7404678955;57203492395;57217271893;24554420100;21935606200;8982748700;57188570624;56317558800;54789101600;7006422317;7003745084;55341341000;57214537462;36134488100;25640569400;57189492881;57104577500;9536598800;57190120326;25721586700;57200650233;57209115087;56989640500;6507719789;35490341500;8946494600;7101874266;55554531900;55752760600;7005203586;7006151934;55345946200;55436842300;57203635779;57218874034;7201594914;55338801300;55458732800;9244954000;57214343044;57218873996;6507848228;57212198554;34968437900;57212198838;57212200093;57198459732;57211031187;6506746457;57218874058;57218874154;6504043008;57218874119;55658058500;55001699000;57204531461;55390690800;57218874005;57218874176;41361927700;25523100000;57203544786;57218873997;","Interaction of convective organization with monsoon precipitation, atmosphere, surface and sea: The 2016 INCOMPASS field campaign in India",2020,"10.1002/qj.3633","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068147381&doi=10.1002%2fqj.3633&partnerID=40&md5=34574f9caff6fa391937b39792a41943","The INCOMPASS field campaign combines airborne and ground measurements of the 2016 Indian monsoon, towards the ultimate goal of better predicting monsoon rainfall. The monsoon supplies the majority of water in South Asia, but forecasting from days to the season ahead is limited by large, rapidly developing errors in model parametrizations. The lack of detailed observations prevents thorough understanding of the monsoon circulation and its interaction with the land surface: a process governed by boundary-layer and convective-cloud dynamics. INCOMPASS used the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft for the first project of this scale in India, to accrue almost 100 h of observations in June and July 2016. Flights from Lucknow in the northern plains sampled the dramatic contrast in surface and boundary-layer structures between dry desert air in the west and the humid environment over the northern Bay of Bengal. These flights were repeated in pre-monsoon and monsoon conditions. Flights from a second base at Bengaluru in southern India measured atmospheric contrasts from the Arabian Sea, over the Western Ghats mountains, to the rain shadow of southeast India and the south Bay of Bengal. Flight planning was aided by forecasts from bespoke 4 km convection-permitting limited-area models at the Met Office and India's NCMRWF. On the ground, INCOMPASS installed eddy-covariance flux towers on a range of surface types, to provide detailed measurements of surface fluxes and their modulation by diurnal and seasonal cycles. These data will be used to better quantify the impacts of the atmosphere on the land surface, and vice versa. INCOMPASS also installed ground instrumentation supersites at Kanpur and Bhubaneswar. Here we motivate and describe the INCOMPASS field campaign. We use examples from two flights to illustrate contrasts in atmospheric structure, in particular the retreating mid-level dry intrusion during the monsoon onset. © 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"55588368000;35419152500;7004210193;6506730508;57205217391;7402942478;","Retrievals of aerosol single scattering albedo by multiwavelength lidar measurements: Evaluations with NASA Langley HSRL-2 during discover-AQ field campaigns",2019,"10.1016/j.rse.2018.12.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059111998&doi=10.1016%2fj.rse.2018.12.022&partnerID=40&md5=c216f0e3c640ec8271379839b99af403","This work focuses on the study and evaluation of the retrievals of aerosol complex refractive index (m = mr + imi) and single scattering albedo (SSA) from the inversion of multi-wavelength lidar measurements, particularly of three backscattering coefficients (β) at 355, 532 and 1064 nm and two extinction coefficients (α) at 355 and 532 nm, typically known as the stand-alone 3β + 2α lidar inversion. The focus is on the well-known regularization technique for spherical particles. It is well known that constraints in the range of refractive indices allowed in the inversion are essential, both for the real (mr) and imaginary (mi) parts, due to the under-determined nature of the problem. Usually these constraints are fixed for a given set of inversions. Using a large database of AERONET retrievals, correlations between retrieved mr and mi are observed and those correlations together with results from the GOCART model are used to define optimized, case-dependent, constraints in the stand-alone 3β + 2α lidar inversion. For each inversion performed, the optimized constraints are computed from the 3β + 2α data using a-priori information of extinction-to-backscattered ratio (LR) and the Angstrom exponent computed with α at 355 and 532 nm. The stand-alone 3β + 2α lidar inversion with optimized, case-dependent, constraints is applied to airborne NASA LaRC HSRL-2 experimental measurements during DISCOVER-AQ. The optimized constraints selected from the measured 3β + 2α are compared with the typing classification based on additional multiwavelength depolarization measurements, showing consistency between aerosol size and absorption range and aerosol typing. Evaluations of the SSA retrieved by the stand-alone 3β + 2α lidar inversion with optimized constraints are done by comparisons with correlative airborne in-situ measured SSA. The agreement between both methodologies is satisfactory for most aerosol types as differences are within the uncertainties of each methodology. © 2018"
"56210720700;57203813004;56083852600;18134565600;57209647985;55350802700;6603548530;6505576518;57200034308;57191428317;57191430389;16308514000;16834406100;55926525800;7101799663;7005859154;35396858200;","Development and characterization of a high-efficiency, aircraft-based axial cyclone cloud water collector",2018,"10.5194/amt-11-5025-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053065814&doi=10.5194%2famt-11-5025-2018&partnerID=40&md5=78926701b2e8f7243b95ca953719579e","<p>A new aircraft-mounted probe for collecting samples of cloud water has been designed, fabricated, and extensively tested. Following previous designs, the probe uses inertial separation to remove cloud droplets from the airstream, which are subsequently collected and stored for offline analysis. We report details of the design, operation, and modelled and measured probe performance.</p><p>Computational fluid dynamics (CFD) was used to understand the flow patterns around the complex interior geometrical features that were optimized to ensure efficient droplet capture. CFD simulations coupled with particle tracking and multiphase surface transport modelling provide detailed estimates of the probe performance across the entire range of flight operating conditions and sampling scenarios.</p><p>Physical operation of the probe was tested on a Lockheed C-130 Hercules (fuselage mounted) and de Havilland Twin Otter (wing pylon mounted) during three airborne field campaigns. During C-130 flights on the final field campaign, the probe reflected the most developed version of the design and a median cloud water collection rate of 4.5&thinsp;mL&thinsp;minĝ'1 was achieved. This allowed samples to be collected over 1-2&thinsp;min under optimal cloud conditions. Flights on the Twin Otter featured an inter-comparison of the new probe with a slotted-rod collector, which has an extensive airborne campaign legacy. Comparison of trace species concentrations showed good agreement between collection techniques, with absolute concentrations of most major ions agreeing within 30&thinsp;%, over a range of several orders of magnitude.</p>. © Author(s) 2018."
"14622650300;7404548584;7102820305;7004472118;7005399437;57203378050;7101984634;","Assessing the Challenges of Surface-Level Aerosol Mass Estimates From Remote Sensing During the SEAC4RS and SEARCH Campaigns: Baseline Surface Observations and Remote Sensing in the Southeastern United States",2018,"10.1029/2017JD028074","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050829247&doi=10.1029%2f2017JD028074&partnerID=40&md5=fcbf598382fb2f3ceff98032f379cc81","The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign conducted in the southeast United States (SEUS) during the summer of 2013 provided a singular opportunity to study local aerosol chemistry and investigate aerosol radiative properties and PM2.5 relationships, focusing on the complexities involved in simplifying the relationship into a linear regression. We utilize three Southeastern Aerosol Research and Characterization network sites and one Environmental Protection Agency Chemical Speciation Network station that afforded simultaneous Aerosol Robotic Network (AERONET) aerosol optical depth (AOD) and aerosol mass, chemistry, and light scattering monitoring. Prediction of AERONET AOD using linear regression of daily-mean PM2.5 during the SEAC4RS campaign yielded r2 of 0.36–0.53 and highly variable slopes across four sites. There were further reductions in PM2.5 predictive skill using Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpetroRadiometer (MISR) AOD data, which have shorter correlation lengths and times relative to surface PM2.5. Long-term trends in aerosol chemistry and optical properties in the SEUS are also investigated and compared to SEAC4RS period data, establishing that the SEUS experienced significant reduction in aerosol mass, corresponding with changes in both aerosol chemistry and optical properties. These changes have substantial impact on the PM2.5-AOD linear regression relationship and reinforce the need for long-term aerosol observation stations in addition to concentrated field campaigns. ©2018. The Authors."
"40461229800;57202019283;7006173230;43461316300;6603237119;43461301000;21646972800;57199013699;24308208100;","HOVERCAT: A novel aerial system for evaluation of aerosol-cloud interactions",2018,"10.5194/amt-11-3969-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049724892&doi=10.5194%2famt-11-3969-2018&partnerID=40&md5=319e0670ae91e276beee65c3df4796e6","Aerosols have a profound impact on cloud microphysics through their ability to serve as ice nucleating particles (INPs). As a result, cloud radiative properties and precipitation processes can be modulated by such aerosol-cloud interactions. However, one of the largest uncertainties associated with atmospheric processes is the indirect effect of aerosols on clouds. The need for more advanced observations of INPs in the atmospheric vertical profile is apparent, yet most ice nucleation measurements are conducted on the ground or during infrequent and intensive airborne field campaigns. Here, we describe a novel measurement platform that is less expensive and smaller (&lt;5 kg) when compared to traditional aircraft and tethered balloon platforms and that can be used for evaluating two modes of ice nucleation (i.e., immersion and deposition). HOVERCAT (Honing On VERtical Cloud and Aerosol properTies) flew during a pilot study in Colorado, USA, up to 2.6 km above mean sea level (1.1 km above ground level) and consists of an aerosol module that includes an optical particle counter for size distributions (0.38-17 μm in diameter) and a new sampler that collects up to 10 filter samples for offline ice nucleation and aerosol analyses on a launched balloon platform. During the May 2017 test flight, total particle concentrations were highest closest to the ground (up to 50 cm-3 at &lt; 50 m above ground level) and up to 2 in 102 particles were ice nucleation active in the immersion mode (at-23 °C). The warmest temperature immersion and deposition mode INPs (observed up to-6 and-40.4 °C, respectively) were observed closest to the ground, but overall INP concentrations did not exhibit an inverse correlation with increasing altitude. HOVERCAT is a prototype that can be further modified for other airborne platforms, including tethered balloon and unmanned aircraft systems. The versatility of HOVERCAT affords future opportunities to profile the atmospheric column for more comprehensive evaluations of aerosol-cloud interactions. Based on our test flight experiences, we provide a set of recommendations for future deployments of similar measurement systems and platforms. © 2018 Author(s)."
"57193957217;7005696579;22954523900;7003414581;24366038500;24448185400;7102680152;25630924500;9432343100;7103357902;7006595513;7003922583;","Helicopter-borne observations of the continental background aerosol in combination with remote sensing and ground-based measurements",2018,"10.5194/acp-18-1263-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041578690&doi=10.5194%2facp-18-1263-2018&partnerID=40&md5=cf7a17babed77d578a701efeada42096","This paper examines the representativeness of ground-based in situ measurements for the planetary boundary layer (PBL) and conducts a closure study between airborne in situ and ground-based lidar measurements up to an altitude of 2300 m. The related measurements were carried out in a field campaign within the framework of the High-Definition Clouds and Precipitation for Advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) in September 2013 in a rural background area of central Europe. The helicopter-borne probe ACTOS (Airborne Cloud and Turbulence Observation System) provided measurements of the aerosol particle number size distribution (PNSD), the aerosol particle number concentration (PNC), the number concentration of cloud condensation nuclei (CCN-NC), and meteorological atmospheric parameters (e.g., temperature and relative humidity). These measurements were supported by the ground-based 3+2 wavelength polarization lidar system PollyXT, which provided profiles of the particle backscatter coefficient (σbsc) for three wavelengths (355, 532, and 1064 nm). Particle extinction coefficient (σext) profiles were obtained by using a fixed backscatter-to-extinction ratio (also lidar ratio, LR). A new approach was used to determine profiles of CCN-NC for continental aerosol. The results of this new approach were consistent with the airborne in situ measurements within the uncertainties. In terms of representativeness, the PNSD measurements on the ground showed a good agreement with the measurements provided with ACTOS for lower altitudes. The ground-based measurements of PNC and CCN-NC are representative of the PBL when the PBL is well mixed. Locally isolated new particle formation events on the ground or at the top of the PBL led to vertical variability in the cases presented here and ground-based measurements are not entirely representative of the PBL. Based on Mie theory (Mie, 1908), optical aerosol properties under ambient conditions for different altitudes were determined using the airborne in situ measurements and were compared with the lidar measurements. The investigation of the optical properties shows that on average the airborne-based particle light backscatter coefficient is 50.1 % smaller for 1064 nm, 27.4 % smaller for 532 nm, and 29.5 % smaller for 355 nm than the measurements of the lidar system. These results are quite promising, since in situ measurement-based Mie calculations of the particle light backscattering are scarce and the modeling is quite challenging. In contrast, for the particle light extinction coefficient we found a good agreement. The airborne-based particle light extinction coefficient was just 8.2 % larger for 532 nm and 3 % smaller for 355 nm, for an assumed LR of 55 sr. The particle light extinction coefficient for 1064 nm was derived with a LR of 30 sr. For this wavelength, the airborne-based particle light extinction coefficient is 5.2 % smaller than the lidar measurements. For the first time, the lidar ratio of 30 sr for 1064 nm was determined on the basis of in situ measurements and the LR of 55 sr for 355 and 532 nm wavelength was reproduced for European continental aerosol on the basis of this comparison. Lidar observations and the in situ based aerosol optical properties agree within the uncertainties. However, our observations indicate that a determination of the PNSD for a large size range is important for a reliable modeling of aerosol particle backscattering."
"6506545080;7203034123;","Simulations of Arctic Mixed-Phase Boundary Layer Clouds: Advances in Understanding and Outstanding Questions",2018,"10.1016/B978-0-12-810549-8.00007-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041218469&doi=10.1016%2fB978-0-12-810549-8.00007-6&partnerID=40&md5=8f1b1a395c808d5f200531154cdee307","An overview of mixed-phase boundary layer cloud simulations emphasizes what detailed studies reveal about the level of understanding of microphysical processes, using analogous liquid-phase boundary layer clouds as a reference for the dynamical conditions. We focus primarily on modeling results from three major field campaign case studies, spanning a range of liquid water path, aerosol loading, cloud temperatures, and active processes (including drizzle, aggregation, and riming). Simulations with detailed microphysics are able to reproduce basic aspects of all three case studies, including continuous ice formation within the context of a well-mixed liquid-cloud-topped layer. However, simulations constrained with measurements of ice nuclei generally underpredict the observed amount of ice present, indicating a possible role for ice multiplication that is poorly established. Assumed ice properties may also bear a significant influence on the water vapor budget and reflectivity properties, but remain imprecisely quantified on a case study basis. © 2018 U.S. Government as represented by the Administrator of the NASA. © 2018 Elsevier Inc. All rights reserved."
"7407016988;7004369046;","Multiscale variability of the atmospheric boundary layer during DYNAMO",2017,"10.1175/JAS-D-17-0182.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040366367&doi=10.1175%2fJAS-D-17-0182.1&partnerID=40&md5=864394a366075e384274eff1fc32285c","Properties of the atmospheric boundary layer (ABL) over the central Indian Ocean are investigated using sounding data obtained during the Dynamics of the MJO (DYNAMO) field campaign in 2011/12. Observations from Gan Island on Addu Atoll, the R/V Revelle, and Malé in the Maldives are used to determine the frequency of well-mixed layers and their mean thermodynamic and wind profiles. Well-mixed boundary layers or mixed layers were observed 68% of the time from the three sites, ranging from ~100-m depth in recovering convective downdraft wakes to ~925 m in undisturbed conditions, with a mean depth of 508 m. At Revelle, the site most representative of the open ocean, the ABL displayed a distinct signal of modulation by the October and November MJOs, with mixed-layer depths gradually increasing through the suppressed phases as the sea surface temperature (SST) increased leading up to the active phases, followed by frequent ABL stabilization and shallow mixed layers in recovering wakes. A distinct diurnal cycle of mixed-layer depths and properties was observed during the MJO suppressed phases in response to a diurnal cycle of the SST under the mostly light-wind, clear-sky conditions. The daytime growth of the mixed layer contributed to an afternoon maximum in cumulus cloud development and rainfall during the suppressed periods by allowing more boundary layer thermals to reach their condensation levels. The variability of the ABL on time scales ranging from convective to diurnal to monthly poses significant challenges for numerical simulations of the MJO and the tropical circulation in general. © 2017 American Meteorological Society."
"7006351262;6505856601;23017945100;36573180000;16444324800;56358933300;35867172500;57193877432;7801483847;6701599239;","Analysis of geostationary satellite-derived cloud parameters associated with environments with high ice water content",2017,"10.5194/amt-10-1359-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017292846&doi=10.5194%2famt-10-1359-2017&partnerID=40&md5=f24d844a96d9cd3a06738abfb9f66cf9","We present an evaluation of the ability of passive broadband geostationary satellite measurements to detect high ice water content (IWC &gt; 1 gm-3) as part of the European High Altitude Ice Crystals (HAIC) project for detection of upper-atmospheric high IWC, which can be a hazard for aviation. We developed a high IWC mask based on measurements of cloud properties using the Cloud Physical Properties (CPP) algorithm applied to the geostationary Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI). Evaluation of the high IWC mask with satellite measurements of active remote sensors of cloud properties (CLOUDSAT/ CALIPSO combined in the DARDAR (raDAR-liDAR) product) reveals that the high IWC mask is capable of detecting high IWC values &gt; 1 gm-3 in the DARDAR profiles with a probability of detection of 60-80 %. The best CPP predictors of high IWC were the condensed water path, cloud optical thickness, cloud phase, and cloud top height. The evaluation of the high IWC mask against DARDAR provided indications that the MSG-CPP high IWC mask is more sensitive to cloud ice or cloud water in the upper part of the cloud, which is relevant for aviation purposes. Biases in the CPP results were also identified, in particular a solar zenith angle (SZA) dependence that reduces the performance of the high IWC mask for SZAs &gt; 60°. Verification statistics show that for the detection of high IWC a trade-off has to be made between better detection of high IWC scenes and more false detections, i.e., scenes identified by the high IWC mask that do not contain IWC &gt; 1 gm-3. However, the large majority of these detections still contain IWC values between 0.1 and 1 gm-3. Comparison of the high IWC mask against results from the Rapidly Developing Thunderstorm (RDT) algorithm applied to the same geostationary SEVIRI data showed that there are similarities and differences with the high IWC mask: the RDT algorithm is very capable of detecting young/new convective cells and areas, whereas the high IWC mask appears to be better capable of detecting more mature and ageing convection as well as cirrus remnants. The lack of detailed understanding of what causes aviation hazards related to high IWC, as well as the lack of clearly defined user requirements, hampers further tuning of the high IWC mask. Future evaluation of the high IWC mask against field campaign data, as well as obtaining user feedback and user requirements from the aviation industry, should provide more information on the performance of the MSG-CPP high IWC mask and contribute to improving the practical use of the high IWC mask. © 2017 Author(s). CC Attribution 3.0 License."
"57193928755;57202055245;55085483100;57204252724;57197189568;7004139091;6602725432;7003811754;","In situ observations of wintertime low-altitude clouds over the Southern Ocean",2017,"10.1002/qj.3011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017561953&doi=10.1002%2fqj.3011&partnerID=40&md5=e7cb7f185777a2d73cddda0f44ee24ad","Cloud droplet concentration (Nd), effective radius (reff) and liquid water content (LWC) measured by a DMT CAPS and an SEA WCM-2000 of wintertime low-altitude clouds over the Southern Ocean (SO) are presented for 20 flights taken over 3 years (June–October, 2013–2015). Such clouds have been reported to have the lowest Nd on record (10–40 cm−3) from the Southern Ocean Cloud Experiment (SOCEX I) field campaign in 1993. Of the total 20 357 one-second records spent in cloud, 38.5% were found to contain ice crystals, primarily in mixed-phase clouds (36.7%). Ice was observed at some point during 19 of the 20 missions. The droplet spectra and temperature range suggest these clouds were often ideal for the Hallett–Mossop ice multiplication process. The average Nd and reff for liquid clouds were 28 (±30) cm−3 and 12.5 (±2.9) µm, which are consistent with those from SOCEX I. Forty-nine percent of all liquid cloud samples were observed to be drizzling with an average drizzle rate of 0.733 mm h−1. As drizzle samples were commonly in the neighbourhood of mixed-phase or non-drizzling clouds, it was rare to observe solid patches of drizzle of greater than 10 s. On average, drizzling clouds had lower Nd and greater reff and LWC than those of non-drizzling clouds. Distinct observations of non-drizzling clouds with relatively high Nd (∼89 cm−3), small reff (∼8.5 µm) and low LWC (∼0.173 g kg−1) were noted for two flights. An initial examination of the local environment and synoptic meteorology for these flights failed to identify any particular forcing that may have led to these unique microphysical properties, although these were the only observations of closed mesoscale cellular convection. This research highlights that greater variability exists in the microphysics of wintertime clouds over the SO, when a wider range of synoptic meteorology is investigated. © 2017 Royal Meteorological Society"
"56722821200;7401796996;8629713500;55816227500;15755995900;7003666669;57208765879;7006783796;","Intercomparisons of marine boundary layer cloud properties from the ARM CAP-MBL campaign and two MODIS cloud products",2017,"10.1002/2016JD025763","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013436141&doi=10.1002%2f2016JD025763&partnerID=40&md5=09a27c9014dd6bf5798e73e8ac14d674","From April 2009 to December 2010, the Department of Energy Atmospheric Radiation Measurement (ARM) program carried out an observational field campaign on Graciosa Island, targeting the marine boundary layer (MBL) clouds over the Azores region. In this paper, we present an intercomparison of the MBL cloud properties, namely, cloud liquid water path (LWP), cloud optical thickness (COT), and cloud-droplet effective radius (CER), among retrievals from the ARM mobile facility and two Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products (Goddard Space Flight Center (GSFC)-MODIS and Clouds and Earth’s Radiant Energy System-MODIS). A total of 63 daytime single-layer MBL cloud cases are selected for intercomparison. Comparison of collocated retrievals indicates that the two MODIS cloud products agree well on both COT and CER retrievals, with the correlation coefficient R&gt;0.95, despite their significant difference in spatial sampling. In both MODIS products, the CER retrievals based on the 2.1 µm band (CER2.1) are significantly larger than those based on the 3.7 µm band (CER3.7). The GSFC-MODIS cloud product is collocated and compared with ground-based ARM observations at several temporal-spatial scales. In general, the correlation increases with more precise collocation. For the 63 selected MBL cloud cases, the GSFC-MODIS LWP and COT retrievals agree reasonably well with the ground-based observations with no apparent bias and correlation coefficient R around 0.85 and 0.70, respectively. However, GSFC-MODIS CER3.7 and CER2.1 retrievals have a lower correlation (R ~ 0.5) with the ground-based retrievals. For the 63 selected cases, they are on average larger than ground observations by about 1.5 µm and 3.0 µm, respectively. Taking into account that the MODIS CER retrievals are only sensitive to cloud top reduces the bias only by 0.5 µm. © 2017. American Geophysical Union. All Rights Reserved."
"57188971800;7005054220;7404327420;7102913661;55314628400;56591838400;7102965584;56893853800;15135583300;7004165697;7003479494;6506458269;7003597162;","Evaluation of deep convective transport in storms from different convective regimes during the DC3 field campaign using WRF-Chem with lightning data assimilation",2017,"10.1002/2017JD026461","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021839484&doi=10.1002%2f2017JD026461&partnerID=40&md5=0b589c76629f966c898157ba7018c82b","Deep convective transport of surface moisture and pollution from the planetary boundary layer to the upper troposphere and lower stratosphere affects the radiation budget and climate. This study analyzes the deep convective transport in three different convective regimes from the 2012 Deep Convective Clouds and Chemistry field campaign: 21 May Alabama air mass thunderstorms, 29 May Oklahoma supercell severe storm, and 11 Junemesoscale convective system (MCS). Lightning data assimilation within the Weather Research and Forecasting (WRF) model coupled with chemistry (WRF-Chem) is utilized to improve the simulations of storm location, vertical structure, and chemical fields. Analysis of vertical flux divergence shows that deep convective transport in the 29 May supercell case is the strongest per unit area, while transport of boundary layer insoluble trace gases is relatively weak in theMCS and airmass cases. Theweak deep convective transport in the strong MCS is unexpected and is caused by the injection into low levels of midlevel clean air by a strong rear inflow jet. In each system, the magnitude of tracer vertical transport is more closely related to the vertical distribution of mass flux density than the vertical distribution of trace gas mixing ratio. Finally, the net vertical transport is strongest in high composite reflectivity regions and dominated by upward transport. © 2017. American Geophysical Union. All Rights Reserved."
"6602078681;6602458644;8293958400;55621952600;7103333823;8147766700;57201726470;56160326300;7401984344;24482355000;7202048112;7201507866;","Satellite sounder observations of contrasting tropospheric moisture transport regimes: Saharan air layers, hadley cells, and atmospheric rivers",2016,"10.1175/JHM-D-16-0163.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007223428&doi=10.1175%2fJHM-D-16-0163.1&partnerID=40&md5=7217b335bd90f04a2ddb6b335b8d4c96","This paper examines the performance of satellite sounder atmospheric vertical moisture profiles under tropospheric conditions encompassing moisture contrasts driven by convection and advection transport mechanisms, specifically Atlantic Ocean Saharan air layers (SALs), tropical Hadley cells, and Pacific Ocean atmospheric rivers (ARs). Operational satellite sounder moisture profile retrievals from the Suomi National Polar-Orbiting Partnership (SNPP) NOAA Unique Combined Atmospheric Processing System (NUCAPS) are empirically assessed using collocated dedicated radiosonde observations (raobs) obtained from ocean-based intensive field campaigns. The raobs from these campaigns provide uniquely independent correlative truth data not assimilated into numerical weather prediction (NWP) models for satellite sounder validation over oceans. Although ocean cases are often considered ""easy"" by the satellite remote sensing community, these hydrometeorological phenomena present challenges to passive sounders, including vertical gradient discontinuities (e.g., strong inversions), as well as persistent uniform clouds, aerosols, and precipitation. It is found that the operational satellite sounder 100-layer moisture profile NUCAPS product performs close to global uncertainty requirements in the SAL/Hadley cell environment, with biases relative to raob within 10% up to 350 hPa. In the more difficult AR environment, bias relative to raob is found to be within 20% up to 400 hPa. In both environments, the sounder moisture retrievals are comparable to NWP model outputs, and cross-sectional analyses show the capability of the satellite sounder for detecting and resolving these tropospheric moisture features, thereby demonstrating a near-real-time forecast utility over these otherwise raob-sparse regions. © 2016 American Meteorological Society."
"7202057166;7005729142;9043417100;56463831800;56442378900;","A global view of atmospheric ice particle complexity",2016,"10.1002/2016GL071267","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85004088950&doi=10.1002%2f2016GL071267&partnerID=40&md5=d123615f950ac0f1f598076adfe5529a","Atmospheric ice particles exist in a variety of shapes and sizes. Single hexagonal crystals like common hexagonal plates and columns are possible, but more frequently, atmospheric ice particles are much more complex. Ice particle shapes have a substantial impact on many atmospheric processes through fall speed, affecting cloud lifetime, to radiative properties, affecting energy balance to name a few. This publication builds on earlier work where a technique was demonstrated to separate single crystals and aggregates of crystals using particle imagery data from aircraft field campaigns. Here data from 10 field programs have been analyzed and ice particle complexity parameterized by cloud temperature for arctic, midlatitude (summer and frontal), and tropical cloud systems. Results show that the transition from simple to complex particles can be as small as 80 µm or as large as 400 µm depending on conditions. All regimes show trends of decreasing transition size with decreasing temperature. ©2016. American Geophysical Union. All Rights Reserved."
"55053404100;7101899854;24344262300;23012437100;57191848056;34969663100;18635289400;16551540700;7202485447;57191845088;6602406924;24172779500;55330758500;","COMMIT in 7-SEAS/BASELINE: Operation of and observations from a novel, mobile laboratory for measuring in-situ properties of aerosols and gases",2016,"10.4209/aaqr.2015.11.0630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994108624&doi=10.4209%2faaqr.2015.11.0630&partnerID=40&md5=f200fdb7c5046cc9117b69395b9dec7c","Trace gases and aerosols (particularly biomass-burning aerosols) have important implications for air quality and climate studies in Southeast Asia (SEA). This paper describes the purpose, operation, and datasets collected from NASA Goddard Space Flight Center’s (NASA/GSFC) Chemical, Optical, and Microphysical Measurements of In-situ Troposphere (COMMIT) laboratory, a mobile platform designed to measure trace gases and optical/microphysical properties of naturally occurring and anthropogenic aerosols. More importantly, the laboratory houses a specialized humidification system to characterize hygroscopic growth/enhancement, a behavior that affects aerosol properties and cloud-aerosol interactions and is generally underrepresented in the current literature. A summary of the trace gas and optical/microphysical measurements is provided, along with additional detail and analysis of data collected from the hygroscopic system during the 2015 Seven South-East Asian Studies (7-SEAS) field campaign. The results suggest that data from the platform are reliable and will complement future studies of aerosols and air quality in SEA and other regions of interest. © Taiwan Association for Aerosol Research."
"56161138500;56513179900;23971806100;15829467700;55574231616;","Observations of water vapor mixing ratio profile and flux in the Tibetan Plateau based on the lidar technique",2016,"10.5194/amt-9-1399-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964394229&doi=10.5194%2famt-9-1399-2016&partnerID=40&md5=14118781b8dea3a7ec167ac54e8a006b","As a part of the third Tibetan Plateau Experiment of Atmospheric Sciences (TIPEX III) in China, a Raman water vapor, cloud and aerosol lidar and a coherent wind lidar were operated in Naqu (31.48° N, 92.06° E) with a mean elevation of more than 4500ma.m.s.l. in summer of 2014. During the field campaign, the water vapor mixing ratio profiles were obtained and validated by radiosonde observations. The mean water vapor mixing ratio in Naqu in July and August was about 9.4 g kg-1 and the values vary from 6.0 to 11.7 g kg-1 near the ground according to the lidar measurements, from which a diurnal variation of water vapor mixing ratio in the planetary boundary layer was also illustrated in this high-elevation area. Furthermore, using concurrent measurements of vertical wind speed profiles from the coherent wind lidar, we calculated the vertical flux of water vapor that indicates the water vapor transport through updraft and downdraft. The fluxes were for a case at night with largescale non-turbulent upward transport of moisture. It is the first application, to our knowledge, to operate continuously atmospheric observations by utilizing multi-disciplinary lidars at the altitude higher than 4000 m, which is significant for research on the hydrologic cycle in the atmospheric boundary layer and lower troposphere in the Tibetan Plateau. © Author(s) 2016."
"6508388178;6603051394;57190728339;7801381830;7003606341;","Modified ultrafast thermometer UFT-M and temperature measurements during Physics of Stratocumulus Top (POST)",2013,"10.5194/amt-6-2043-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882754171&doi=10.5194%2famt-6-2043-2013&partnerID=40&md5=7d2d0a598d66c8de7336884905c77c35","A modified UFT-M version of the ultrafast airborne thermometer UFT, aimed at in-cloud temperature measurements, was designed for the Physics of Stratocumulus Top (POST) field campaign. Improvements in its construction resulted in the sensor's increased reliability, which provided valuable measurements in 15 of the 17 flights. Oversampling the data allowed for the effective correction of the artefacts resulting from the interference with electromagnetic transmissions from on-board avionic systems and the thermal noise resulting from the sensor construction. The UFT-M records, when averaged to the 1.4 and 55 m resolutions, compared to the similar records of a thermometer in a Rosemount housing, indicate that the housing distorts even low-resolution airborne temperature measurements. Data collected with the UFT-M during the course of POST characterise the thermal structure of stratocumulus and capping inversion with the maximum resolution of ∼1 cm. In this paper, examples of UFT-M records are presented and discussed. © Author(s) 2013."
"35740180800;9043417100;7006235542;7103016965;7005729142;","Factors influencing ice formation and growth in simulations of a mixed-phase wave cloud",2012,"10.1029/2012MS000163","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84867814092&doi=10.1029%2f2012MS000163&partnerID=40&md5=bfd40d1c74141b7183d31870d81efab4","In this paper, numerical simulations of an orographically induced wave cloud sampled in-situ during the ICE-L (Ice in Clouds Experiment - Layer clouds) field campaign are performed and compared directly against the available observations along various straight and level flight paths. The simulations are based on a detailed mixed-phase bin microphysics model embedded within a 1-D column framework with the latest parameterizations for heterogeneous ice nucleation and an adaptive treatment of ice crystal growth based on the evolution of crystal habit. The study focuses on the second of two clouds sampled on 16th November 2007, the in-situ data from which exhibits some interesting and more complex microphysics than other flights from the campaign. The model is used to demonstrate the importance of both heterogeneous and homogeneous nucleation in explaining the in-situ observations of ice crystal concentration and habit, and how the ability to isolate the influence of both nucleation mechanisms helps when quantifying active IN concentrations. The aspect ratio and density of the simulated ice crystals is shown to evolve in a manner consistent with the in-situ observations along the flight track, particularly during the transition from the mixed-phase region of the cloud to the ice tail dominated by homogeneous nucleation. Some additional model runs are also performed to explore how changes in IN concentration and the value of the deposition coefficient for ice affect the competition between heterogeneous and homogeneous ice formation in the wave cloud, where the Factorial Method is used to isolate and quantify the effect of such non-linear interactions. The findings from this analysis show that the effect on homogeneous freezing rates is small, suggesting that any competition between the microphysical variables is largely overshadowed by the strong dynamical forcing of the cloud in the early stages of ice formation. © 2012. American Geophysical Union. All Rights Reserved."
"36343109300;7402717381;15724736600;","Impacts of terminal velocity on the trajectory of winter precipitation types",2012,"10.1016/j.atmosres.2012.03.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84865110699&doi=10.1016%2fj.atmosres.2012.03.008&partnerID=40&md5=ac66d270bac2e82dae978163c34917f8","It is common to observe many types of precipitation such as wet snow, ice pellets, and freezing rain during winter storms. The vertical temperature profile composed of a melting layer aloft and a refreezing layer below, plays an important role in the formation of these precipitation types. The horizontal wind also influences the particle trajectories and displaces them into different atmospheric conditions as they fall. This study investigates the sensitivity of the precipitation type distribution and intensity at the surface to the precipitation terminal velocity variation down through the atmosphere. To address this issue, the trajectories of precipitation types are investigated using a bulk microphysics scheme coupled with a two-dimensional kinematic cloud model. The model is initialized with idealized atmospheric conditions associated with a warm front leading to many types of precipitation at the surface. A systematic study was carried out assuming two melting snow scenarios: snow melting aloft into rain and snow melting aloft into semi-melted snow and rain. First, the results show good agreement with observations collected during the Canadian CloudSat/Callipso Validation Project (C3VP) field campaign. Second, the sensitivity experiments show that the intensity and location of precipitation vary depending on the melting scheme. The precipitation rate at the surface can be up to 55% higher if snow melts into semi-melted snow and rain compared to directly into rain. Overall, the terminal velocity of the precipitation types observed during winter storms is critical for better predicting the location and intensity of precipitation. © 2012 Elsevier B.V."
"57199193474;6602094828;14018977200;55037642100;6506723397;55037471000;55033888000;37561696600;54395555200;37083842700;36450912200;57199315807;7006244721;55032763900;22954771200;36338127900;57206421204;","The Pre-Depression Investigation of Cloud-systems in the Tropics (PREDICT) field campaign: Perspectives of early career scientists",2012,"10.1175/BAMS-D-11-00024.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857551243&doi=10.1175%2fBAMS-D-11-00024.1&partnerID=40&md5=313b2fbbae2a8c097e097e39de1ac92c","The Pre-Depression Investigation of Cloud-systems in the Tropics (PREDICT) field experiment successfully gathered data from four developing and four decaying/nondeveloping tropical disturbances over the tropical North Atlantic basin between 15 August and 30 September 2010. The invaluable roles played by early career scientists (ECSs) throughout the campaign helped make possible the successful execution of the field program's mission to investigate tropical cyclone formation. ECSs provided critical meteorological information-often obtained from novel ECS-created products-during daily weather briefings that were used by the principal investigators in making mission planning decisions. Once a Gulfstream V (G-V) flight mission was underway, ECSs provided nowcasting support, relaying information that helped the mission scientists to steer clear of potential areas of turbulence aloft. Data from these missions, including dropsonde and GPS water vapor profiler data, were continually obtained, processed, and quality-controlled by ECSs. The dropsonde data provided National Hurricane Center forecasters and PREDICT mission scientists with real-time information regarding the characteristics of tropical disturbances. These data and others will serve as the basis for multiple ECS-led research topics over the years to come and are expected to provide new insights into the tropical cyclone formation process. PREDICT also provided invaluable educational and professional development experiences for ECSs, including the opportunity to critically evaluate observational evidence for tropical cyclone development theories and networking opportunities with their peers and established scientists in the field © 2012 American Meteorological Society."
"11440916900;7102331727;7402049334;","Airborne measurement of liquid and total water content",2011,"10.1175/JTECH-D-10-05035.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-82655181754&doi=10.1175%2fJTECH-D-10-05035.1&partnerID=40&md5=6d93141401110748aeb6c04c706d800b","Two identical liquid water content (LWC) King probes-one total water content/liquid water content (TWC/LWC) Nevzorov probe and two constant-temperature T probes that are different in size to distinguish particles of different densities and diameters (section 2c)-were flown during the Alliance Icing Research Study (AIRS) II field campaign in the fall of 2003. This paper assesses measurements performed during several flights in mostly stratiform clouds. The two LWC King probes tracked well; however, discrepancies of up to 0.1 g m-3 for 1-s LWC measurements of 0.3 g m-3 were observed. Agreement between probes of different geometry and size was generally favorable, while levels of disagreement between the probes changed during numerous cloud penetrations from less than 20% up to a factor of 2, varying with flight conditions and microphysical structure of the cloud. Disagreement between probes was even larger when detecting ice water content (IWC). Measurement differences were attributed to different collection efficiencies resulting from preferred particle size, shape, and density and local aerodynamic effects around the aircraft. Measurements from a single probe are subject to uncertainty at a single point in time beyond the noise and drift level of the instrument. This uncertainty is evaluated considering particle habit, diameter, and density, and probe geometry and size, in addition to particle impact, breakup/splash, and bounce. Froma working point of view, the intercomparison of several probes is subject to real but unknown spatial differences because of different locations between air samples. Comparison of identical probes is not appropriate because each measurement in itself is unique by definition. Thus, instead of duplication of instruments, subject to these levels of agreement, the use of a single probe is a practical approach while remaining aware of its limitations and capabilities. © 2011 American Meteorological Society."
"15724736600;7402717381;7004484970;","Vertical reflectivity profiles of precipitation over Iqaluit, Nunavut during Autumn 2007",2011,"10.1016/j.atmosres.2010.10.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650774231&doi=10.1016%2fj.atmosres.2010.10.009&partnerID=40&md5=668ab18ca87278f141accdc35c8b3e66","In this study, information from surface observations, soundings and ground-based X-band Doppler radar is used to examine and better understand three significant precipitation events in Iqaluit, Nunavut. These observations were collected between 15 October 2007 and 5 December 2007 during the Storm Studies in the Arctic (STAR) field campaign and collectively these three events produced 65% of the precipitation during that period although the total of these was only 24. mm. All three events also had periods in which there was reflectivity aloft above the radar but not at the surface. This indicates the presence of dry layers where sublimation of falling particles would have been a factor or the impact of advection of particles away from the vertical radar beam. Furthermore, clouds were inferred to have occurred in as many as five layers. Photographs of the hydrometeors showed aggregation and riming which were consistent with vertical velocities inferred from Doppler information. Overall, the results indicate that there are many similarities and differences between events that occur in the Western and Eastern Canadian Arctic regions. One such similarity is that the precipitation from these storms will be difficult to measure from spaceborne measurement systems. © 2010 Elsevier B.V."
"16242027100;6603109490;56000281400;","An examination of the aerosol semi-direct effect for a polluted case of the ISDAC field campaign",2011,"10.1029/2011JD015649","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80755126985&doi=10.1029%2f2011JD015649&partnerID=40&md5=23ff550c0b4af61f514324a7a4ad9964","The semi-direct aerosol effect is examined with a mesoscale meteorological model for a polluted Arctic haze episode at Barrow, Alaska during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). Initialized with chemical and aerosol reanalysis fields from a global chemistry model, the WRF/Chem mesoscale model is used to simulate a polluted event over Alaska and its environs on 18-21 April 2008. It is shown that the atmosphere is sensitive to changes in the black carbon concentration, even though it comprises just a small fraction (less than one percent) of the total aerosol mass. Comparisons with a baseline run (which does not include aerosol radiative effects) show that in regions where black carbon is concentrated, the semi-direct effect heats the lower troposphere by about 0.15 K. Additional sensitivity tests reveal that the heating is more uniform and higher in magnitude by up to 0.1 K when the initial concentration of black carbon is doubled, and a reduction in heating occurs when black carbon is reduced to zero. At Barrow, atmospheric warming is sensitive to variations in the black carbon concentration, and heating generally occurs above 0.5 km altitude where black carbon is located. A more stably stratified lower troposphere due to the warming aloft and surface cooling from the aerosol direct effect leads to a redistribution and reduction in the cloud optical thickness and liquid water content. This cloud reduction decreases the amount of downward surface longwave radiation and further lowers the surface temperature at Barrow. Copyright 2011 by the American Geophysical Union."
"35796308500;6602281350;7006392180;","Tropical land cover change detection with polarimetric SAR data",2010,"10.1109/IGARSS.2010.5653215","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650900338&doi=10.1109%2fIGARSS.2010.5653215&partnerID=40&md5=0e33062fd248c34eee56a707b4e50be2","There is an increasing need for fast and accurate data on tropical land cover status, and a baseline for land cover monitoring. Remotely sensed SAR data are not sensitive to cloud cover and can be useful for such purpose. Polarimetric SAR data are available in orbital systems, such as RADARSAT-2, and still have to be tested for the classification of tropical land cover and the detection of land cover change, particularly forest conversion. This work presents a study of RADARSAT-2 polarimetric images, acquired in two different dates (September 2008 and October 2009), to assess their potential in classifying forest and non-forest classes in Brazilian Amazonia. SAR images were acquired following different orbit and incidence angles, which anticipated varied conditions for images interpretation and classes discrimination. The complex SAR data were classified based on the distance of Wishart, and information from field campaigns was used for the training and test samples. Classification results were compared to evaluate possibilities for change detection in the forest cover. Classification accuracy figures were around 80%. The use of RADARSAT-2 images allowed the mapping of land cover and land cover change, considering forest and non-forest classes. © 2010 IEEE."
"23048575400;7005174340;6603382350;7103204204;57203405965;7202245296;6603800142;23990280900;7006813055;7003729315;57214160655;7403682442;","A new method to retrieve the aerosol layer absorption coefficient from airborne flux density and actinic radiation measurements",2010,"10.1029/2009JD013636","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955390982&doi=10.1029%2f2009JD013636&partnerID=40&md5=362bb4cf29a78e8a99656054ee96f10b","A new method is presented to derive the mean value of the spectral absorption coefficient of an aerosol layer from combined airborne measurements of spectral net irradiance and actinic flux density. While the method is based on a theoretical relationship of radiative transfer theory, it is applied to atmospheric radiation measurements for the first time. The data have been collected with the Spectral Modular Airborne Radiation Measurement System (SMART-Albedometer), the Solar Spectral Flux Radiometer (SSFR), and the Actinic Flux Spectroradiometer (AFSR) during four field campaigns between 2002 and 2008 (the Saharan Mineral Dust Experiment (SAMUM), the Influence of Clouds on the Spectral Actinic Flux in the Lower Troposphere (INSPECTRO) project, and the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites and Aerosol, Radiation, and Cloud Processes Affecting Arctic Climate (ARCTAS/ARCPAC) projects). The retrieval algorithm is tested in a series of radiative transfer model runs and then applied to measurement cases with different aerosol species and loading. The method is shown to be a feasible approach to obtain the mean aerosol absorption coefficient across a given accessible altitude range. The results indicate that the method is viable whenever the difference of the net irradiance at the top and bottom of a layer is equal to or higher than the measurement uncertainty for net irradiance. This can be achieved by a high optical depth or a low single-scattering albedo within the layer. Copyright 2010 by the American Geophysical Union."
"12141789600;6603764973;7006242396;7101984634;","Satellite-derived cloud top pressure product validation using aircraftbased cloud physics lidar data from the ATReC field campaign",2007,"10.1080/01431160500391965","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547099825&doi=10.1080%2f01431160500391965&partnerID=40&md5=070e40e5585f57caa097e5d60c806b32","The primary objective of this study was to assess the accuracy of satellite-derived estimates of cloud-top height (CTH). These estimates were derived using hourly data from the Geostationary Operational Environmental Satellite (GOES-12) Imager and Sounder instruments. In addition, CTHs were derived using data from the MODerate resolution Imaging Spectrometer (MODIS), located on the polar-orbiting Aqua platform. Cloud physics lidar (CPL) data taken during the Atlantic-THORPEX Regional Campaign (ATReC) were used as the reference data set. Two cases were examined, one containing clouds at many different levels (5 December 2003) and one consisting entirely of mid-level clouds (between 4 and 10 km, 28 November 2003). For the first case, 19.4% of the Sounder pixels and 28.0% of the Imager pixels were within ± 0.5 km of the CPL measurement, while 51.5% of the Sounder pixels and 64.3% of the Imager pixels were within ± 1.5 km. For the second case, 29.7% of the Sounder pixels and 39.9% of the Imager pixels were within ± 0.5 km of the CPL measurement, while 85.2% of the Sounder pixels and 85.1% of the Imager pixels were within ± 1.5 km. The results indicate that MODIS CTH retrievals may provide an improvement over heights derived using geostationary instruments, especially for cases where cloud heights are not highly variable."
"6602590070;","A laser-optical device for measuring cloud and drizzle drop size distributions",1998,"10.1127/metz/7/1998/53","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0010446706&doi=10.1127%2fmetz%2f7%2f1998%2f53&partnerID=40&md5=930f1944032716ac1e1a5fd2cab3155e","The Malvern Particle Sizer (MPS), a laser-optical device, was used for measuring cloud, drizzle and raindrops. In this paper it is shown that the instrument is suitable for investigations on cloud and drizzle droplet size distributions due to the need of high number concentrations in the measuring volume. Furthermore it is shown that with only two instruments (MPS and Joss-Waldvogel-disdrometer) the whole drop size range from small cloud drops up to large raindrops is detectable. During the field campaign FELDEX 95 at Kleiner Feldberg drop distributions were measured, both with the MPS and with a disdrometer. Two periods were investigated. Differences in the development of the cloud drop size spectra were observed, and could be attributed to totally different raindrop spectra. In one case broader cloud drop spectra led to rather narrow drizzle spectra with large concentrations of small raindrops, typical for warm rain formation. These spectra differ completely from the corresponding Marshall-Palmer (MP)-distributions. In the other case narrow cloud drop spectra were associated with broad raindrop spectra which were in good agreement with Marshall-Palmer-distributions. Differences in the rain formation processes can explain these observations. At the end some improvements of the MPS-system are discussed which would be helpful for future work to overcome problems that occurred during the field measurements."
"57193213111;7102266120;34881780600;12803904100;7003570692;36908840200;34772240500;","The Impact of Variable Land-Atmosphere Coupling on Convective Cloud Populations Observed During the 2016 HI-SCALE Field Campaign",2019,"10.1029/2019MS001727","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070783371&doi=10.1029%2f2019MS001727&partnerID=40&md5=8a688f15ded6b4dfa7c08ebb0d9d4db5","We use a large-eddy simulation model with a nested domain configuration (297 and 120 km wide) and an interactive land surface parameterization to simulate the complex population of shallow clouds observed on 30 August 2016 during the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems campaign conducted in north-central Oklahoma. Shallow convective clouds first formed over southeast Oklahoma and then spread toward the northwest into southern Kansas. By the early afternoon, the relatively uniform shallow cloud field became more complex in which some regions became nearly cloud free and in other regions larger shallow clouds developed with some transitioning to deeper, precipitating convection. We show that the model reproduces the observed heterogeneity in the cloud populations only when realistic variations in soil moisture are used to initialize the model. While more variable soil moisture and to a lesser extent cool lake temperatures drive the initial spatial heterogeneity in the cloud populations, precipitation-driven cold pools become an important factor after 1300 CST. When smoother soil moisture variations are used in the model, more uniform shallow cloud populations are predicted with far fewer clouds that transition to deeper, precipitating convection that produce cold pools. An algorithm that tracks thousands of individual cumulus show that the more realistic soil moisture distributions produces clouds that are larger and have a longer lifetime. The results suggest that shallow and deep convection parameterizations used by mesoscale models need to account for the effects of variable land-atmosphere interactions and cold pools. ©2019. The Authors."
"36538539800;53881502900;56942554300;6603051005;56401135900;22036956700;14009037000;6602675912;","Multiscale applications of two online-coupled meteorology-chemistry models during recent field campaigns in Australia, Part I: Model description and WRF/Chem-ROMS evaluation using surface and satellite data and sensitivity to spatial grid resolutions",2019,"10.3390/atmos10040189","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064085281&doi=10.3390%2fatmos10040189&partnerID=40&md5=75dc5ac6b7c8cd92c77b3e0692e15fdc","Air pollution and associated human exposure are important research areas in Greater Sydney, Australia. Several field campaigns were conducted to characterize the pollution sources and their impacts on ambient air quality including the Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2), and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). In this work, the Weather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are applied during these field campaigns to assess the models' capability in reproducing atmospheric observations. The model simulations are performed over quadruple-nested domains at grid resolutions of 81-, 27-, 9-, and 3-km over Australia, an area in southeastern Australia, an area in New South Wales, and the Greater Sydney area, respectively. A comprehensive model evaluation is conducted using surface observations from these field campaigns, satellite retrievals, and other data. This paper evaluates the performance of WRF/Chem-ROMS and its sensitivity to spatial grid resolutions. The model generally performs well at 3-, 9-, and 27-km resolutions for sea-surface temperature and boundary layer meteorology in terms of performance statistics, seasonality, and daily variation. Moderate biases occur for temperature at 2-m and wind speed at 10-m in the mornings and evenings due to the inaccurate representation of the nocturnal boundary layer and surface heat fluxes. Larger underpredictions occur for total precipitation due to the limitations of the cloud microphysics scheme or cumulus parameterization. The model performs well at 3-, 9-, and 27-km resolutions for surface O3 in terms of statistics, spatial distributions, and diurnal and daily variations. The model underpredicts PM2.5 and PM10 during SPS1 and MUMBA but overpredicts PM2.5 and underpredicts PM10 during SPS2. These biases are attributed to inaccurate meteorology, precursor emissions, insufficient SO2 conversion to sulfate, inadequate dispersion at finer grid resolutions, and underprediction in secondary organic aerosol. The model gives moderate biases for net shortwave radiation and cloud condensation nuclei but large biases for other radiative and cloud variables. The performance of aerosol optical depth and latent/sensible heat flux varies for different simulation periods. Among all variables evaluated, wind speed at 10-m, precipitation, surface concentrations of CO, NO, NO2, SO2, O3, PM2.5, and PM10, aerosol optical depth, cloud optical thickness, cloud condensation nuclei, and column NO2 show moderate-to-strong sensitivity to spatial grid resolutions. The use of finer grid resolutions (3- or 9-km) can generally improve the performance for those variables. While the performance for most of these variables is consistent with that over the U.S. and East Asia, several differences along with future work are identified to pinpoint reasons for such differences. © 2019 by the authors."
"57200511248;12806808600;56102840300;57057115500;57202641460;","Identifying crop planting areas using Fourier-transformed feature of time series MODIS leaf area index and sparse-representation-based classification in the North China Plain",2019,"10.1080/01431161.2018.1492181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049569665&doi=10.1080%2f01431161.2018.1492181&partnerID=40&md5=3b0ed319d8c5663a40e44f0fe1bec234","Accurate information of crop distribution is vital for agricultural industry and food security, which gives rise to a strong demand for timely crop mapping. This study applies a method that combines sparse representation and harmonic characteristics derived from time series Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) to identify crop planting areas to the north of the Yellow River in the North China Plain, where winter wheat and maize are widely cultivated. The upper envelope Savitzky–Golay filter was applied on the yearly time series MODIS LAI pixel by pixel to minimize the effects of anomalous values caused by atmospheric variability and cloud contamination. The Fourier transform method was then employed to extract the key parameters from the Savitzky–Golay filtered LAI. Totally about 11 parameters were extracted, including the amplitudes of the terms 0–5 and the phases of the terms 1–5 of the Savitzky–Golay filtered LAI, and were taken as the features for the crop identification. Based on the training samples of the identified crops, which were obtained through field campaigns and Google Earth images, the online dictionary learning algorithm was applied to construct the dictionary for identifying the crops. With the dictionary, orthogonal matching pursuit algorithm was applied to obtain sparse representation coefficients of the identified samples. Then crops were identified using the minimum reconstruction errors which were calculated by the dictionary and the sparse representation coefficients of each category. Winter wheat, spring maize, summer maize, cotton, and orchard planting areas from 2003 to 2016 in the study area were identified. The accuracy of the identification was evaluated by the confusion matrix. Average overall identification accuracy in the 14 years was 78.67%, with a kappa coefficient (κ) of 0.75. Annual overall accuracy from 2003 to 2016 was from 70.57% to 83.71%, and κ were from 0.66 to 0.81. These results indicate that the accuracy of crop identification is high. Compared with traditional classification methods, such as supervised classification, the approach developed in this study is feasible and efficient for identifying crop distribution in the study area. Repeated and expensive ground sampling year after year is not needed, which effectively reduces computation cost. The findings of this study can provide valuable implications for crop condition monitoring and yield estimation in the region. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group."
"36538539800;56942554300;53881502900;6603051005;56401135900;22036956700;14009037000;6602675912;","Multiscale applications of two online-coupled meteorology-chemistry models during recent field campaigns in Australia, Part II: Comparison of WRF/Chem and WRF/Chem-ROMS and impacts of air-sea interactions and boundary conditions",2019,"10.3390/ATMOS10040210","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068913452&doi=10.3390%2fATMOS10040210&partnerID=40&md5=129a43be6504b9ff9f06b68c6c2d0749","Air-sea interactions play an important role in atmospheric circulation and boundary layer conditions through changing convection processes and surface heat fluxes, particularly in coastal areas. These changes can affect the concentrations, distributions, and lifetimes of atmospheric pollutants. In this Part II paper, the performance of theWeather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are intercompared for their applications over quadruple-nested domains in Australia during the three following field campaigns: The Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2) and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). The results are used to evaluate the impact of air-sea interaction representation in WRF/Chem-ROMS on model predictions. At 3, 9, and 27 km resolutions, compared to WRF/Chem, the explicit air-sea interactions in WRF/Chem-ROMS lead to substantial improvements in simulated sea-surface temperature (SST), latent heat fluxes (LHF), and sensible heat fluxes (SHF) over the ocean, in terms of statistics and spatial distributions, during all three field campaigns. The use of finer grid resolutions (3 or 9 km) effectively reduces the biases in these variables during SPS1 and SPS2 by WRF/Chem-ROMS, whereas it further increases these biases for WRF/Chem during all field campaigns. The large differences in SST, LHF, and SHF between the two models lead to different radiative, cloud, meteorological, and chemical predictions. WRF/Chem-ROMS generally performs better in terms of statistics and temporal variations for temperature and relative humidity at 2 m, wind speed and direction at 10 m, and precipitation. The percentage differences in simulated surface concentrations between the two models are mostly in the range of ±10% for CO, OH, and O3, ±25% for HCHO, ±30% for NO2, ±35% for H2O2, ±50% for SO2, ±60% for isoprene and terpenes, ±15% for PM2.5, and ±12% for PM10. WRF/Chem-ROMS at 3 km resolution slightly improves the statistical performance of many surface and column concentrations. WRF/Chem simulations with satellite-constrained boundary conditions (BCONs) improve the spatial distributions and magnitudes of column CO for all field campaigns and slightly improve those of the column NO2 for SPS1 and SPS2, column HCHO for SPS1 and MUMBA, and column Oc for SPS2 at 3 km over the Greater Sydney area. The satellite-constrained chemical BCONs reduce the model biases of surface CO, NO, and O3 predictions at 3 km for all fieldcampaigns, surface PM2.5 predictions at 3 km for SPS1 and MUMBA, and surface PM10 predictions at all grid resolutions for all field campaigns. A more important role of chemical BCONs in the Southern Hemisphere, compared to that in the Northern Hemisphere reported in this work, indicates a crucial need in developing more realistic chemical BCONs for O3 in the relatively clean SH. © 2019 by the authors."
"57200123456;6701810892;7801565183;9846154100;55253694900;15923105200;","Impact of air mass conditions and aerosol properties on ice nucleating particle concentrations at the High Altitude Research Station Jungfraujoch",2018,"10.3390/atmos9090363","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053612294&doi=10.3390%2fatmos9090363&partnerID=40&md5=4afa7c4f5383c77f9f5ef2a2245b90f3","Ice nucleation is the source of primary ice crystals in mixed-phase clouds. Only a small fraction of aerosols called ice nucleating particles (INPs) catalyze ice formation, with their nature and origin remaining unclear. In this study, we investigate potential predictor parameters of meteorological conditions and aerosol properties for INP concentrations at mixed-phase cloud condition at 242 K. Measurements were conducted at the High Altitude Research Station Jungfraujoch (Switzerland, 3580 m a.s.l.), which is located predominantly in the free troposphere (FT) but can occasionally receive injections from the boundary layer (BLI). Measurements are taken during a long-term study of eight field campaigns, allowing for the first time an interannual (2014-2017) and seasonal (spring, summer, and winter) distinction of high-time-resolution INP measurements. We investigate ranked correlation coefficients between INP concentrations and meteorological parameters and aerosol properties. While a commonly used parameterization lacks in predicting the observed INP concentrations, the best INP predictor is the total available surface area of the aerosol particles, with no obvious seasonal trend in the relationship. Nevertheless, the predicting capability is less pronounced in the FT, which might be caused by ageing effects. Furthermore, there is some evidence of anthropogenic influence on INP concentrations during BLI. Our study contributes to an improved understanding of ice nucleation in the free troposphere, however, it also underlines that a knowledge gap of ice nucleation in such an environment exists. © 2018 by the authors."
"55915364000;7403401100;54279446400;57189377456;16023843200;7006708207;","Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol-cloud interactions",2018,"10.5194/amt-11-2583-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046770454&doi=10.5194%2famt-11-2583-2018&partnerID=40&md5=52e5eed2fb024c27d030f2923a2acfb6","The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts) in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA). In atmospheric research, lightweight RPAs ( < 2.5kg) are now able to accurately measure atmospheric wind vectors, even in a cloud, which provides essential observing tools for understanding aerosol-cloud interactions. The European project BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: Towards a Holistic UnderStanding) focuses on these specific interactions. In particular, vertical wind velocity at cloud base is a key parameter for studying aerosol-cloud interactions. To measure the three components of wind, a RPA is equipped with a five-hole probe, pressure sensors, and an inertial navigation system (INS). The five-hole probe is calibrated on a multi-axis platform, and the probe-INS system is validated in a wind tunnel. Once mounted on a RPA, power spectral density (PSD) functions and turbulent kinetic energy (TKE) derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland), a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10%. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological conditions. © Author(s) 2018."
"57200560468;6701382162;7202119915;24066817400;57200567392;6508384349;","Use of an end-to-end-simulator to analyze CYGNSS",2018,"10.1175/JTECH-D-17-0036.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041695744&doi=10.1175%2fJTECH-D-17-0036.1&partnerID=40&md5=4ac77f901c79276d952fbe3f95e8b82a","Tropical convection during the onset of two Madden-Julian oscillation (MJO) events, in October and December of 2011, was simulated using the Weather Research and Forecasting (WRF)Model. Observations from the Dynamics of the MJO (DYNAMO) field campaign were assimilated into the WRF Model for an improved simulation of the mesoscale features of tropical convection. The WRF simulations with the assimilation of DYNAMO data produced realistic representations of mesoscale convection related to westerly wind bursts (WWBs) as well as downdraft-induced gust fronts. An end-to-end simulator (E2ES) for the Cyclone Global Navigation Satellite System (CYGNSS) mission was then applied to the WRF dataset, producing simulated CYGNSS near-surface wind speed data. The results indicated that CYGNSS could detect mesoscale wind features such as WWBs and gust fronts even in the presence of simulated heavy precipitation. This study has two primary conclusions as a consequence: 1) satellite simulators could be used to examine a mission's capabilities for accomplishing secondary tasks and 2) CYGNSS likely will provide benefits to future tropical oceanic field campaigns that should be considered during their planning processes. © 2018 American Meteorological Society."
"57192700389;8277424000;7004011998;35262555900;7005434178;7006484268;","Toward a polarimetric radar classification scheme for coalescence-dominant precipitation: Application to complex terrain",2017,"10.1175/JHM-D-17-0016.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044532158&doi=10.1175%2fJHM-D-17-0016.1&partnerID=40&md5=9ae5a959dd28581fb4114f51ecde87a3","Accurate quantitative precipitation estimation over mountainous basins is of great importance because of their susceptibility to natural hazards. It is generally difficult to obtain reliable precipitation information over complex areas because of the scarce coverage of ground observations, the limited coverage from operational radar networks, and the high elevation of the study sites. Warm-rain processes have been observed in several flash flood events in complex terrain regions. While they lead to high rainfall rates from precipitation growth due to collision-coalescence of droplets in the cloud liquid layer, their characteristics are often difficult to identify. X-band mobile dual-polarization radars located in complex terrain areas provide fundamental information at high-resolution and at low atmospheric levels. This study analyzes a dataset collected in North Carolina during the 2014 Integrated Precipitation and Hydrology Experiment (IPHEx) field campaign over a mountainous basin where the NOAA/National Severe Storm Laboratory's X-band polarimetric radar (NOXP) was deployed. Polarimetric variables are used to isolate collision-coalescence microphysical processes. This work lays the basis for classification algorithms able to identify coalescence-dominant precipitation by merging the information coming from polarimetric radar measurements. The sensitivity of the proposed classification scheme is tested with different rainfall-rate retrieval algorithms and compared to rain gauge observations. Results show the inadequacy of rainfall estimates when coalescence identification is not taken into account. This work highlights the necessity of a correct classification of collision-coalescence processes, which can lead to improvements in quantitative precipitation estimation. Future studies will aim at generalizing this scheme by making use of spaceborne radar data. © 2017 American Meteorological Society."
"57219529090;55357355600;56237281700;56255280300;7501626996;57196021613;23004944100;","SIMULATING VARIOUS TERRESTRIAL and UAV LIDAR SCANNING CONFIGURATIONS for UNDERSTORY FOREST STRUCTURE MODELLING",2017,"10.5194/isprs-annals-IV-2-W4-59-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030972914&doi=10.5194%2fisprs-annals-IV-2-W4-59-2017&partnerID=40&md5=caa0e8cbd598640156df909c469bc69e","Information about the 3D structure of understory vegetation is of high relevance in forestry research and management (e.g., for complete biomass estimations). However, it has been hardly investigated systematically with state-of-the-art methods such as static terrestrial laser scanning (TLS) or laser scanning from unmanned aerial vehicle platforms (ULS). A prominent challenge for scanning forests is posed by occlusion, calling for proper TLS scan position or ULS flight line configurations in order to achieve an accurate representation of understory vegetation. The aim of our study is to examine the effect of TLS or ULS scanning strategies on (1) the height of individual understory trees and (2) understory canopy height raster models. We simulate full-waveform TLS and ULS point clouds of a virtual forest plot captured from various combinations of max. 12 TLS scan positions or 3 ULS flight lines. The accuracy of the respective datasets is evaluated with reference values given by the virtually scanned 3D triangle mesh tree models. TLS tree height underestimations range up to 1.84 m (15.30 % of tree height) for single TLS scan positions, but combining three scan positions reduces the underestimation to maximum 0.31 m (2.41 %). Combining ULS flight lines also results in improved tree height representation, with a maximum underestimation of 0.24 m (2.15 %). The presented simulation approach offers a complementary source of information for efficient planning of field campaigns aiming at understory vegetation modelling. © Authors 2017."
"55332291100;6603494091;6603816167;57202531041;","Ice crystal characterization in cirrus clouds: A sun-tracking camera system and automated detection algorithm for halo displays",2017,"10.5194/amt-10-2499-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85024889240&doi=10.5194%2famt-10-2499-2017&partnerID=40&md5=98d0a82f835c83458955168702e48bc4","Halo displays in the sky contain valuable information about ice crystal shape and orientation: e.g., the 22° halo is produced by randomly oriented hexagonal prisms while parhelia (sundogs) indicate oriented plates. HaloCam, a novel sun-tracking camera system for the automated observation of halo displays is presented. An initial visual evaluation of the frequency of halo displays for the ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques) field campaign from October to mid-November 2014 showed that sundogs were observed more often than 22° halos. Thus, the majority of halo displays was produced by oriented ice crystals. During the campaign about 27-% of the cirrus clouds produced 22° halos, sundogs or upper tangent arcs. To evaluate the HaloCam observations collected from regular measurements in Munich between January 2014 and June 2016, an automated detection algorithm for 22° halos was developed, which can be extended to other halo types as well. This algorithm detected 22° halos about 2-% of the time for this dataset. The frequency of cirrus clouds during this time period was estimated by co-located ceilometer measurements using temperature thresholds of the cloud base. About 25-% of the detected cirrus clouds occurred together with a 22° halo, which implies that these clouds contained a certain fraction of smooth, hexagonal ice crystals. HaloCam observations complemented by radiative transfer simulations and measurements of aerosol and cirrus cloud optical thickness (AOT and COT) provide a possibility to retrieve more detailed information about ice crystal roughness. This paper demonstrates the feasibility of a completely automated method to collect and evaluate a long-term database of halo observations and shows the potential to characterize ice crystal properties. © 2017 Author(s)."
"57192167236;7005634455;6602926744;37861937500;57192155152;6602073516;","Evaluation of the AMPS boundary layer simulations on the Ross Ice Shelf, Antarctica, with unmanned aircraft observations",2017,"10.1175/JAMC-D-16-0339.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027438092&doi=10.1175%2fJAMC-D-16-0339.1&partnerID=40&md5=c04ff63f57b9e360c05cac70b9478ac0","Accurately predicting moisture and stability in the Antarctic planetary boundary layer (PBL) is essential for low-cloud forecasts, especially when Antarctic forecasters often use relative humidity as a proxy for cloud cover. These forecasters typically rely on the Antarctic Mesoscale Prediction System (AMPS) Polar Weather Research and Forecasting (Polar WRF) Model for high-resolution forecasts. To complement the PBL observations from the 30-m Alexander Tall Tower! (ATT) on the Ross Ice Shelf as discussed in a recent paper by Wille and coworkers, a field campaign was conducted at the ATT site from 13 to 26 January 2014 using Small Unmanned Meteorological Observer (SUMO) aerial systems to collect PBL data. The 3-km-resolution AMPS forecast output is combined with the global European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAI), SUMO flights, and ATT data to describe atmospheric conditions on the Ross Ice Shelf. The SUMO comparison showed that AMPS had an average 2-3 m s-1 high wind speed bias from the near surface to 600 m, which led to excessive mechanical mixing and reduced stability in the PBL. As discussed in previous Polar WRF studies, the Mellor-Yamada-Janjic PBL scheme is likely responsible for the high wind speed bias. The SUMO comparison also showed a near-surface 10-15-percentage-point dry relative humidity bias in AMPS that increased to a 25-30-percentage-point deficit from 200 to 400 m above the surface. A large dry bias at these critical heights for aircraft operations implies poor AMPS low-cloud forecasts. The ERAI showed that the katabatic flow from the Transantarctic Mountains is unrealistically dry in AMPS. © 2017 American Meteorological Society."
"57198593283;57206332144;24802663500;25624545600;7003907406;57203405965;13403957300;10040054900;57203233100;","Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign",2016,"10.1016/j.atmosres.2016.08.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982095316&doi=10.1016%2fj.atmosres.2016.08.004&partnerID=40&md5=e2644f1129f07a579a02413fbd238034","We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius reff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius reff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases. © 2016"
"57008250400;7101752236;9535707500;14321759900;55974019700;8684037700;6506385754;8942525300;8942524900;","Aerosol indirect effects on glaciated clouds. Part I: Model description",2016,"10.1002/qj.2791","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992306091&doi=10.1002%2fqj.2791&partnerID=40&md5=b5730f9effcecbb19dd6799fc574ee53","Various improvements were made to a state-of-the-art aerosol–cloud model and comparison of the model results with observations from field campaigns was performed. The strength of this aerosol–cloud model is in its ability to explicitly resolve all the known modes of heterogeneous cloud droplet activation and ice crystal nucleation. The model links cloud particle activation with the aerosol loading and chemistry of seven different aerosol species. These improvements to the model resulted in more accurate prediction especially of droplet and ice crystal number concentrations in the upper troposphere and enabled the model to directly sift the aerosol indirect effects based on the chemistry and concentration of the aerosols. In addition, continental and maritime cases were simulated for the purpose of validating the aerosol–cloud model and for investigating the critical microphysical and dynamical mechanisms of aerosol indirect effects from anthropogenic solute and solid aerosols, focusing mainly on glaciated clouds. The simulations showed that increased solute aerosols reduced cloud particle sizes by about 5 μm and inhibited warm rain processes. Cloud fractions and their optical thicknesses were increased quite substantially in both cases. Although liquid mixing ratios were boosted, there was however a substantial reduction of ice mixing ratios in the upper troposphere owing to the increase in snow production aloft. These results are detailed in the subsequent parts of this study. © 2016 Royal Meteorological Society"
"7401793588;57208765879;23026201900;57189097770;50662209800;8627503500;55330123800;","Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC4RS using bi-spectral reflectance measurements within the 1.88μm water vapor absorption band",2016,"10.5194/amt-9-1743-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965116630&doi=10.5194%2famt-9-1743-2016&partnerID=40&md5=ece632bb715b4907f54356e53c7df771","Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a nonabsorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 μm water vapor absorption band, namely the 1.83 and 1.93 μm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick singlelayer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-Atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds. © Author(s) 2016. CC Attribution 3.0 License."
"57192869079;7004242319;7004003763;57192872717;6701546267;57210590791;7003831563;","A comparison of X-band polarization parameters with in situ microphysical measurements in the comma head of two winter cyclones",2016,"10.1175/JAMC-D-16-0059.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008477772&doi=10.1175%2fJAMC-D-16-0059.1&partnerID=40&md5=080eb11131ab831d355ec1721b7f7513","Since the advent of dual-polarization radar, methods of classifying hydrometeors by type from measured polarization variables have been developed. The deterministic approach of existing hydrometeor classification algorithms of assigning only one dominant habit to each radar sample volume does not properly consider the distribution of habits present in that volume, however. During the Profiling of Winter Storms field campaign, the ""NSF/NCAR C-130"" aircraft, equipped with in situ microphysical probes, made multiple passes through the comma heads of two cyclones as the Mobile Alabama X-band dual-polarization radar performed range-height indicator scans in the same plane as the C-130 flight track. On 14-15 February and 21-22 February 2010, 579 and 202 coincident data points, respectively, were identified when the plane was within 10 s (~1 km) of a radar gate. For all particles that occurred for times within different binned intervals of radar reflectivity ZHH and of differential reflectivity ZDR, the reflectivity-weighted contribution of each habit and the frequency distributions of axis ratio and sphericity were determined. This permitted the determination of habits that dominate particular ZHH and ZDR intervals; only 40% of the ZHH-ZDR bins were found to have a habit that contributes over 50% to the reflectivity in that bin. Of these bins, only 12% had a habit that contributes over 75% to the reflectivity. These findings show the general lack of dominance of a given habit for a particular ZHH and ZDR and suggest that determining the probability of specific habits in radar volumes may be more suitable than the deterministic methods currently used. © 2016 American Meteorological Society."
"6506328135;34881780600;37099564300;55476830600;56583515100;7102266120;","Moist process biases in simulations of the Madden-Julian oscillation episodes observed during the AMIE/DYNAMO field campaign",2016,"10.1175/JCLI-D-15-0349.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957831476&doi=10.1175%2fJCLI-D-15-0349.1&partnerID=40&md5=d3aae1c87203a385b043550098f2253a","Two Madden-Julian oscillation (MJO) episodes observed during the 2011 Atmospheric Radiation Measurement ProgramMJO InvestigationExperiment (AMIE)/DYNAMOfield campaign are simulated using a regional model with various cumulus parameterizations, a regional cloud-permitting model, and a global variableresolution model with a high-resolution region centered over the tropical Indian Ocean. Model biases in relationships relevant to existing instability theories of MJO are examined and their relative contributions to the overall model errors are quantified using a linear statistical model. The model simulations capture the observed approximately log-linear relationship between moisture saturation fraction and precipitation, but precipitation associated with the given saturation fraction is overestimated especially at low saturation fraction values. This bias is amajor contributor to the excessive precipitation during the suppressed phase of MJO. After accounting for this bias using a linear statisticalmodel, the spatial and temporal structures of themodel-simulatedMJOepisodes are much improved, and what remains of the biases is strongly correlated with biases in saturation fraction. The excess precipitation bias during the suppressed phase of the MJO episodes is accompanied by excessive columnintegrated radiative forcing and surface evaporation.Alarge portion of the bias in evaporation is related to biases in wind speed, which are correlated with those of precipitation. These findings suggest that the precipitation bias sustains itself at least partly by cloud radiative feedbacks and convection-surface wind interactions. © 2016 American Meteorological Society."
"55228409700;57203348817;55958422800;","Processes controlling precipitation in shallow, orographic, trade wind convection",2015,"10.1175/JAS-D-14-0333.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943370023&doi=10.1175%2fJAS-D-14-0333.1&partnerID=40&md5=f31468005de014a945a2b5ea09816360","A sharp reduction in precipitation was observed on the island of Dominica in the Caribbean during a 2011 field campaign when the trade winds weakened and convection transitioned from mechanically to thermally driven. The authors propose four hypotheses for this reduction, which relate to (i) the triggering mechanism, (ii) dry-air entrainment, (iii) giant sea-salt aerosol, and (iv) small-island-derived aerosol. The plausibility of the first three hypotheses is the focus of this study. Aircraft observations show the dynamics of the orographic cumulus clouds at flight level are surprisingly similar, irrespective of how they are triggered. However, the orographic cumulus clouds are consistently shallower when the trade winds are weak, which the authors attribute to a drier and shallower cloud layer compared to days with stronger trade winds. The strong negative influence of dry-air entrainment in a drier environment on cumulus depth and liquid water content is qualitatively demonstrated using an entraining plume model and the WRF Model. Although the models appear more sensitive than observations to entrainment and cloud size, the sensitivity tests have some resemblance to observations. The authors also find evidence of sea-salt aerosol entering the base of marine cumulus on strong wind days using an aircraft-mounted lidar and other instruments. Although each hypothesis is plausible, the complex interplay of these processes makes determining the controlling mechanisms difficult. Ultimately, the authors' analysis rejects the hypothesis (i) triggering, while supporting (ii) entrainment and (iii) sea-salt aerosol. © 2015 American Meteorological Society."
"26643615000;6603431534;34881780600;7405489798;7402480218;36243762400;36634069800;7404633868;6701754792;","Stratiform and convective precipitation observed by multiple radars during the DYNAMO/AMIE experiment",2014,"10.1175/JAMC-D-13-0311.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910672368&doi=10.1175%2fJAMC-D-13-0311.1&partnerID=40&md5=1a6ec966b6ebd31bb5d487e7ef967f57","In this study, methods of convective/stratiform precipitation classification and surface rain-rate estimation based on the Atmospheric Radiation Measurement Program (ARM) cloud radar measurements were developed and evaluated. Simultaneous and collocated observations of the Ka-band ARM zenith radar (KAZR), two scanning precipitation radars [NCAR S-band/Ka-band Dual Polarization, Dual Wavelength Doppler Radar (S-PolKa) and Texas A&amp;M University Shared Mobile Atmospheric Research and Teaching Radar (SMART-R)], and surface precipitation during the Dynamics of the Madden-Julian Oscillation/ARM MJOInvestigation Experiment (DYNAMO/AMIE) field campaign were used. The motivation of this study is to apply the unique long-term ARM cloud radar observations without accompanying precipitation radars to the study of cloud life cycle and precipitation features under different weather and climate regimes. The resulting convective/stratiform classification from KAZR was evaluated against precipitation radars. Precipitation occurrence and classified convective/stratiform rain fractions from KAZR compared favorably to the collocated SMART-R and S-PolKa observations. Both KAZR and S-PolKa radars observed about 5% precipitation occurrence. The convective (stratiform) precipitation fraction is about 18% (82%). Collocated disdrometer observations of two days showed an increased number concentration of small and large raindrops in convective rain relative to dominant small raindrops in stratiform rain. The composite distributions of KAZR reflectivity and Doppler velocity also showed distinct structures for convective and stratiform rain. These evidences indicate that the method produces physically consistent results for the two types of rain. A new KAZR-based, two-parameter [the gradient of accumulative radar reflectivity Ze (GAZ) below 1 km and near-surface Ze] rain-rate estimation procedure was developed for both convective and stratiform rain. This estimate was compared with the exponential Z-R (reflectivity-rain rate) relation. The relative difference between the estimated and surface-measured rainfall rates showed that the two-parameter relation can improve rainfall estimation relative to the Z-R relation. © 2014 American Meteorological Society."
"6507017517;55017656900;7003591311;39762774100;7801381830;7005310521;7004885872;","A comparative study of the response of modeled non-drizzling stratocumulus to meteorological and aerosol perturbations",2013,"10.5194/acp-13-2507-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874908221&doi=10.5194%2facp-13-2507-2013&partnerID=40&md5=35321fcc5be15f957b1de88e931cb456","The impact of changes in aerosol and cloud droplet concentration (<i>N</i>a and <i>N</i>d) on the radiative forcing of stratocumulus-topped boundary layers (STBLs) has been widely studied. How these impacts compare to those due to variations in meteorological context has not been investigated in a systematic fashion for non-drizzling overcast stratocumulus. In this study we examine the impact of observed variations in meteorological context and aerosol state on daytime, non-drizzling overcast stratiform evolution, and determine how resulting changes in cloud properties compare. <br><br> Using large-eddy simulation (LES) we create a model base case of daytime southeast Pacific coastal stratocumulus, spanning a portion of the diurnal cycle (early morning to near noon) and constrained by observations taken during the VOCALS (VAMOS Ocean-Atmosphere-Land Study) field campaign. We perturb aerosol and meteorological properties around this base case to investigate the stratocumulus response. We determine perturbations in the cloud top jumps in potential temperature θ and total water mixing ratio <i>q</i>t from ECMWF Re-analysis Interim data, and use a set of <i>N</i>d values spanning the observable range. To determine the cloud response to these meteorological and aerosol perturbations, we compute changes in liquid water path (LWP), bulk optical depth (τ) and cloud radiative forcing (CRF). <br><br> We find that realistic variations in the thermodynamic jump properties can elicit a response in the cloud properties of τ and shortwave (SW) CRF that are on the same order of magnitude as the response found due to realistic changes in aerosol state (i.e <i>N</i>d). In response to increases in <i>N</i>d, the cloud layer in the base case thinned due to increases in evaporative cooling and entrainment rate. This cloud thinning somewhat mitigates the increase in τ resulting from increases in <i>N</i>d. On the other hand, variations in θ and <i>q</i>t jumps did not substantially modify <i>N</i>d. The cloud layer thickens in response to an increase in the θ jump and thins in response to an increase in the <i>q</i>t jump, both resulting in a τ and SW CRF response comparable to those found from perturbations in <i>N</i>d. Longwave CRF was not substantially altered by the perturbations we tested. <br><br> We find that realistic variations in meteorological context can elicit a response in CRF and τ on the same order of magnitude as, and at times larger than, that response found due to realistic changes in aerosol state. We estimate the limits on variability of cloud top jump properties required for accurate observation of aerosol SW radiative impacts on stratocumulus, and find strict constraints: less than 1 K and 1 g kg&minus;1 in the early morning hours, and order 0.1 K and 0.1 g kg&minus;1 close to solar noon. These constraints suggest that accurately observing aerosol radiative impacts in stratocumulus may be challenging as co-variation of meteorological properties may obfuscate aerosol-cloud interactions. © Author(s) 2013."
"6602078681;6602458644;7004866567;8687046600;57198558737;47861260200;57201726470;7103333823;","On the angular effect of residual clouds and aerosols in clear-sky infrared window radiance observations 2. Satellite experimental analyses",2013,"10.1029/2012JD018260","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880261946&doi=10.1029%2f2012JD018260&partnerID=40&md5=8a19be80ebe792803c729c067c17c4f2","This paper continues an investigation into the zenith angular effect of cloud-contamination within ""clear-sky"" infrared (IR) radiance observations commonly used in the retrieval of environmental data records (EDRs), which include ""cloud-cleared radiances"" (as is typical from hyper/ultra spectral IR sounders), as well as ""cloud-masked"" data (as is typical from imagers). The simple probability of clear line of sight (PCLoS) models and sensitivity studies of Part 1 (Nalli et al., 2012a) are corroborated with experimental analyses of environmental satellite data products as functions of sensor zenith angle, including sounder cloud-cleared radiances (CCRs) and retrieved effective cloud fraction, as well as narrowband imager cloud masking. Analyses of hyperspectral microwindow calc - obs are performed using MetOp-A Infrared Atmospheric Sounding Interferometer (IASI) CCR observations matched to dedicated radiosonde observations (RAOBs) during intensive validation field campaigns. The IASI calc - obs are found to exhibit a systematic positive bias with a strong concave-up variation with satellite zenith angle (i.e., an increasing positive bias symmetric over the scanning range) on the order of 1-3 K in magnitude, a signal associated with both residual clouds and dust aerosols. This is corroborated by analysis of the IASI retrieved effective cloud fraction product compared to the expected angular variations predicted by the PCLoS models, which show that the observed concave-up calc - obs variation may be the result of contamination by mid-to-upper tropospheric clouds. Finally, a corollary global analysis of the MetOp-A Advanced Very High Resolution Radiometer (AVHRR) cloud-mask shows concave-up variation that may be underestimating the angular variation for global ensembles containing clouds with vertical development (i.e., aspect ratios >0.5). The results presented in this work thus support the sensitivity studies of Part 1, indicating that contamination by residual clouds and/or aerosols within clear-sky observations can have a measurable concave-up impact on the angular agreement of observations with calculations. ©2012. American Geophysical Union. All Rights Reserved."
"57213493573;55896920900;18134195800;","A subgrid parameterization scheme for precipitation",2012,"10.5194/gmd-5-499-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860244342&doi=10.5194%2fgmd-5-499-2012&partnerID=40&md5=2c64d0eb9e6fb1facb33943bd7d1885a","With increasing computing power, the horizontal resolution of numerical weather prediction (NWP) models is improving and today reaches 1 to 5 km. Nevertheless, clouds and precipitation formation are still subgrid scale processes for most cloud types, such as cumulus and stratocumulus. Subgrid scale parameterizations for water vapor condensation have been in use for many years and are based on a prescribed probability density function (PDF) of relative humidity spatial variability within the model grid box, thus providing a diagnosis of the cloud fraction. A similar scheme is developed and tested here. It is based on a prescribed PDF of cloud water variability and a threshold value of liquid water content for droplet collection to derive a rain fraction within the model grid. Precipitation of rainwater raises additional concerns relative to the overlap of cloud and rain fractions, however. The scheme is developed following an analysis of data collected during field campaigns in stratocumulus (DYCOMS-II) and fair weather cumulus (RICO) and tested in a 1-D framework against large eddy simulations of these observed cases. The new parameterization is then implemented in a 3-D NWP model with a horizontal resolution of 2.5 km to simulate real cases of precipitating cloud systems over France. © 2012 Author(s)."
"7003620360;6601922531;7003431244;35614095500;6505768455;7005941217;35490380800;","A comparison of light backscattering and particle size distribution measurements in tropical cirrus clouds",2011,"10.5194/amt-4-557-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79953002986&doi=10.5194%2famt-4-557-2011&partnerID=40&md5=eb67b544b6462fe9aa36d80a722ba47e","An FSSP-100 Optical Particle Counter designed to count and size particles in the micron range and a backscattersonde that measures in-situ particle optical properties such as backscatter and depolarization ratio, are part of the payload of the high altitude research aircraft M55 Geophysica. This aircraft was deployed in tropical field campaigns in Bauru, Brasil (TROCCINOX, 2004) Darwin, Australia (SCOUT-Darwin, 2005) and Ouagadougou, Burkina Faso (SCOUT-AMMA, 2006). In those occasions, measurements of particle size distributions and optical properties within cirrus cloud were performed. Scope of the present work is to assess and discuss the consistency between the particle volume backscatter coefficient observed by the backscattersonde and the same parameter retrieved by optical scattering theory applied to particle size distributions as measured by the FSSP-100. In addition, empirical relationships linking the optical properties measured in-situ by the backscattersonde, which generally can be obtained by remote sensing techniques (LIDAR), and microphysical bulk properties like total particle number, surface and volume density will be presented and discussed. © 2011 Author(s)."
"22935118800;16421230600;7003836546;","Analysis of a two-layer cloud system with RAMS model and comparison to airborne observations",2007,"10.1007/s10652-007-9043-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-36749020574&doi=10.1007%2fs10652-007-9043-6&partnerID=40&md5=dac0c30741b098d8e0b83a3974c2c610","A three-dimensional numerical model (Regional Atmospheric Modeling System - RAMS) was used to study the formation and evolution of water forms in a two-layer cloud structure observed during a field campaign over Brest (France). The model performance in regular operations, using conventional meteorological data as initial and lateral boundary conditions, was also examined. Remote sensing observations of the cloud system and in-situ aircraft data, selected during the campaign, were used to validate the model outputs. The model simulations showed that the lower cloud formation was characterized by high number concentration of pristine ice and snow, while the concentration of aggregates, graupel and hail were considerably lower. Hydrometeors in liquid phase appeared demonstrating high number concentration and water content on the top of this layer. The upper cloud layer consisted only of frozen water substances in lower amounts. The qualitative and quantitative comparison of the model-calculated meteorological and microphysical fields to the available observational data revealed that the model reflected fairly well the cloud structure (e.g., the spatio-temporal variability of the cloud parameters, the geometry of the cloud system). However, there were deviations as far as the model underestimating the ice water content (IWC) and number concentration (Nt) fields is concerned, especially at the atmospheric layer between 2.5 and 4 km of altitude. These deviations of the model simulated quantities from the measured ones may be attributed either to the performance of the model's microphysics scheme, to instrument inaccuracies and to the local disturbance caused by the aircraft. © Springer Science+Business Media B.V. 2007."
"7801634218;55708190300;7006728825;","Measurements of ultragiant aerosol particles in the atmosphere from the small cumulus microphysics study",2002,"10.1175/1520-0426(2002)019<0402:MOUAPI>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036330510&doi=10.1175%2f1520-0426%282002%29019%3c0402%3aMOUAPI%3e2.0.CO%3b2&partnerID=40&md5=3e392bd5d24516042bc3fac02a224792","Ultragiant aerosol particles (UGA) are potentially important for warm rain formation because of their ability to initiate coalescence immediately upon entering a cloud, so it is desirable to obtain local estimates during any field campaign that studies warm rain. Estimates of UGA in clear air from a one-dimensional optical array probe averaged over long time periods from the Small Cumulus Microphysics Study have been published in the literature, but further analysis and comparisons to other probes, presented here, show that the data on which these estimates were based were probably contaminated by noise. A possible explanation for the noise in the probe is given, as are new upper limits, based on few or no particles detected by a two-dimensional optical array probe."
"6602620698;6505773188;57190842718;6602694234;","Acid pollutants in air and precipitaion/deposition at the Sudeten Mountains, Poland",1995,"10.1007/BF01186149","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029635890&doi=10.1007%2fBF01186149&partnerID=40&md5=f8176c2fa4771425750c3896380d47a0","The results of several separately performed field studies on air quality in south-western Poland (Black Triangle) are presented In the period 1988-1993 atmospheric aerosol measurement and precipitation/deposition samples were collected at three locations of mountain region (810-1490 m asl). Precipitation was monitored in forest ecosystem using a 24-gauge network was carried out during June-October 1992 and 1993. The occurence of cloud at ground level over hills is difficult to categorize and quantify in mountain terrain and has constituted a basic part of our studies. Precipitation/deposition samples (seven rain and three cloud collectors) in the Karkonosze Mountains were collected over the period 1994-1995 (four field campaigns were conducted) to examine aqueous chemical interactions between constituents in samples. Meteorological data measured at the site included temperature, humidity, wind speed and direction and the amount of precipitation. © 1995 Kluwer Academic Publishers."
"54954460700;7004347243;7006363107;7102913661;7006829318;7402711358;25029309200;14048087800;8359591200;6602356428;57216412488;","Comprehensive isoprene and terpene gas-phase chemistry improves simulated surface ozone in the southeastern US",2020,"10.5194/acp-20-3739-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083464343&doi=10.5194%2facp-20-3739-2020&partnerID=40&md5=78768a7ceea9cfea46a0085b5bfe7262","Ozone is a greenhouse gas and air pollutant that is harmful to human health and plants. During the summer in the southeastern US, many regional and global models are biased high for surface ozone compared to observations. Past studies have suggested different solutions including the need for updates to model representation of clouds, chemistry, ozone deposition, and emissions of nitrogen oxides (NOx ) or biogenic hydrocarbons. Here, due to the high biogenic emissions in the southeastern US, more comprehensive and updated isoprene and terpene chemistry is added into CESM/CAM-chem (Community Earth System Model/Community Atmosphere Model with full chemistry) to evaluate the impact of chemistry on simulated ozone. Comparisons of the model results with data collected during the Studies of Emissions Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign and from the US EPA (Environmental Protection Agency) CASTNET (Clean Air Status and Trends Network) monitoring stations confirm the updated chemistry improves simulated surface ozone, ozone precursors, and NOx reservoir compounds. The isoprene and terpene chemistry updates reduce the bias in the daily maximum 8 h average (MDA8) surface ozone by up to 7 ppb. In the past, terpene oxidation in particular has been ignored or heavily reduced in chemical schemes used in many regional and global models, and this study demonstrates that comprehensive isoprene and terpene chemistry is needed to reduce surface ozone model biases. Sensitivity tests were performed in order to evaluate the impact of lingering uncertainties in isoprene and terpene oxidation on ozone. Results suggest that even though isoprene emissions are higher than terpene emissions in the southeastern US, remaining uncertainties in isoprene and terpene oxidation have similar impacts on ozone due to lower uncertainties in isoprene oxidation. Additionally, this study identifies the need for further constraints on the aerosol uptake of organic nitrates derived from isoprene and terpenes in order to reduce uncertainty in simulated ozone. Although the updates to isoprene and terpene chemistry greatly reduce the ozone bias in CAM-chem, a large bias remains. Evaluation against SEAC4RS field campaign results suggests future improvements to horizontal resolution and cloud parameterizations in CAM-chem may be particularly important for further reducing this bias. © 2019 Sissa Medialab Srl. All rights reserved."
"16308514000;55536734900;57195361786;57126848900;56210720700;7003729315;7005891596;6508356419;57195361985;56016057500;14035836100;57209647985;35095482200;55619886800;57195488312;55350802700;56083852600;55688930000;7403247998;18134565600;7005035762;","Atmospheric Research Over the Western North Atlantic Ocean Region and North American East Coast: A Review of Past Work and Challenges Ahead",2020,"10.1029/2019JD031626","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082333727&doi=10.1029%2f2019JD031626&partnerID=40&md5=dfb25e5b161ae8871df70d24b5d51596","Decades of atmospheric research have focused on the Western North Atlantic Ocean (WNAO) region because of its unique location that offers accessibility for airborne and ship measurements, gradients in important atmospheric parameters, and a range of meteorological regimes leading to diverse conditions that are poorly understood. This work reviews these scientific investigations for the WNAO region, including the East Coast of North America and the island of Bermuda. Over 50 field campaigns and long-term monitoring programs, in addition to 715 peer-reviewed publications between 1946 and 2019, have provided a firm foundation of knowledge for these areas. Of particular importance in this region has been extensive work at the island of Bermuda that is host to important time series records of oceanic and atmospheric variables. Our review categorizes WNAO atmospheric research into eight major categories, with some studies fitting into multiple categories (relative %): aerosols (25%); gases (24%); development/validation of techniques, models, and retrievals (18%); meteorology and transport (9%); air-sea interactions (8%); clouds/storms (8%); atmospheric deposition (7%); and aerosol-cloud interactions (2%). Recommendations for future research are provided in the categories highlighted above. ©2020. American Geophysical Union. All Rights Reserved."
"35999651600;13408025900;","Accident Damage Analysis Module (ADAM): Novel European Commission tool for consequence assessment—Scientific evaluation of performance",2019,"10.1016/j.psep.2019.07.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069895347&doi=10.1016%2fj.psep.2019.07.007&partnerID=40&md5=448e683f0de7535769b7dd09cd69d3eb","This paper summarises the scientific evaluation of the performance of a novel modelling tool, the Accident Damage Assessment Module (ADAM), developed by the Joint Research Centre (JRC) of the European Commission (EC) to assess the consequences of an industrial accident resulting from an unintended release of a dangerous substance. The ADAM tool is specifically intended to assist Competent Authorities in the European Union (EU) and European Economic Area (EEA), and their supporting research institutions, responsible for the implementation of the Seveso Directive in their countries, as well as governmental and research organisations of EU Accession and Candidate Countries, and European Neighbourhood Policy countries involved in chemical accident prevention and preparedness. In particular, the tool provides decision-making support to various functions associated with industrial risk management, enforcement and oversight, including risk analysis, land-use and emergency planning, inspection and monitoring, and the preparation and review of safety reports. Consequence assessment models are characterised by high level of complexity and of uncertainty. It is therefore of paramount importance to assess their limits. The scientific evaluation was conducted across the entire consequence assessment cycle, including the source terms and the physical effects calculations associated with the concentration toxics after airborne dispersion, the thermal radiation of chemical fires, and the explosion of vapour flammable clouds. The evaluation described in this paper was conducted on a series of relevant scenarios, by benchmarking the outcome of ADAM with the results obtained by similar software tools and with the experimental data obtained on a series of reference field campaigns, as taken from the literature. © 2019 The Authors"
"57196414331;7004393835;56495287900;7403401100;6602137606;12645700600;55196799200;","Experimental study of the aerosol impact on fog microphysics",2019,"10.5194/acp-19-4323-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063947900&doi=10.5194%2facp-19-4323-2019&partnerID=40&md5=9431c4a9cc0b46c1a56c541e68c71197","Comprehensive field campaigns dedicated to fog life cycle observation were conducted during the winters of 2010.2013 at the Instrumented Site for Atmospheric Remote Sensing Research (SIRTA) observatory in a suburb of Paris. In order to document their properties, in situ microphysical measurements collected during 23 fog events induced by both radiative cooling and stratus lowering are examined here. They reveal large variability in number, concentration and size of both aerosol background before the fog onset and fog droplets according to the different cases. The objective of this paper is to evaluate the impact of aerosol particles on the fog microphysics. To derive an accurate estimation of the actual activated fog droplet number concentration Nact, we determine the hygroscopicity parameter k, the dry and the wet critical diameter and the critical supersaturation for each case by using an iterative procedure based on the k-Kohler theory that combines cloud condensation nuclei (CCN), dry particle and droplet size distribution measurements. Our study reveals low values of the derived critical supersaturation occurring in fog with a median of 0.043 %. Consequently, the median dry and wet activation diameters are 0.39 and 3.79 μm, respectively, leading to a minor fraction of the aerosol population activated into droplets. The corresponding Nact values are low, with median concentrations of 53.5 and 111 cm-3 within the 75th percentile. The activated fraction of aerosols exhibits remarkably low correlation with k values, which reflects the chemical composition of the aerosols. On the contrary, the activated fraction exhibits a strong correlation with the inferred critical diameter throughout the field campaigns. This suggests that the variability in the activated fraction is mostly driven by particle size, while variations in aerosol composition are of secondary importance. Moreover, our analysis suggests that the supersaturation reached in fog could be lowered by the aerosol number concentration, which could contribute to the sink term of water vapor during the radiative cooling. Although radiative fogs are usually associated with higher aerosol loading than stratus-lowering events, our analysis also reveals that the activated fraction at the beginning of the event is similar for both types of fog. However, the evolution of the droplet concentration during the fog life cycle shows significant differences between both types of fog. This work demonstrates that an accurate calculation of supersaturation is required to provide a realistic representation of fog microphysical properties in numerical models. © 2019 Author(s)."
"57201193898;7201798916;7004174939;7003478309;8643810200;37037211400;57194868290;36169987900;18134565600;6603372665;7404061081;","Retrievals of Aerosol Size Distribution, Spherical Fraction, and Complex Refractive Index From Airborne In Situ Angular Light Scattering and Absorption Measurements",2019,"10.1029/2018JD030009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058164452&doi=10.1029%2f2018JD030009&partnerID=40&md5=1f55e5a9b4b5264b57c670d2e4f87d0c","Aerosol models, composed of size distribution, complex refractive index, and spherical fraction, are derived from a new synergistic retrieval of airborne in situ angular scattering measurements made by the Polarized Imaging Nephelometer and absorption measurements from the Particle Soot Absorption Photometer. The data utilized include phase function (F11), degree of polarization (−F12/F11), and absorption coefficient (βabs) measured at low relative humidities during the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) and Deep Convection Clouds and Chemistry (DC3) field campaigns. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to these measurements to obtain summaries of particle properties that are optically consistent with the original measurements. A classification scheme is then used to categorize the corresponding retrieval results. Inversions performed on the DC3 measurements indicate the presence of a significant amount of dust-like aerosol in the inflow of storms sampled during this campaign, with the quantity of dust present depending strongly on the underlying surface features. In the SEAC4RS data, the retrieved size distributions were found to be remarkably similar among a range of aerosol types, including urban and industrial, biogenic, and biomass burning (BB) emissions. These aerosol types were found to have average fine mode volume median radii 0.155 ≤ rvf ≤ 0.163μm and lognormal standard deviations 0.32 ≤ σf ≤ 0.36. There were, however, consistent differences between the angular scattering patterns of the BB samples and the other particle types. The GRASP retrieval predominantly attributed these differences to elevated real and imaginary refractive indices in the BB samples (m532nm≈1.55+0.007i) relative to the two other categories (m532nm≈1.51+0.004i). ©2019. American Geophysical Union. All Rights Reserved."
"57190445508;55683899000;55414424200;26022906800;6602221672;15922073800;15080710300;56429387500;7102062952;7007155334;12446450200;50661395000;8941151400;47761279900;7102160108;36106098500;56647321100;16047956100;7410177774;57203776263;13405658600;","Constraining nucleation, condensation, and chemistry in oxidation flow reactors using size-distribution measurements and aerosol microphysical modeling",2018,"10.5194/acp-18-12433-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052754408&doi=10.5194%2facp-18-12433-2018&partnerID=40&md5=6dd48f71f47fbfe0156caa5fd4239ddb","Oxidation flow reactors (OFRs) allow the concentration of a given atmospheric oxidant to be increased beyond ambient levels in order to study secondary organic aerosol (SOA) formation and aging over varying periods of equivalent aging by that oxidant. Previous studies have used these reactors to determine the bulk OA mass and chemical evolution. To our knowledge, no OFR study has focused on the interpretation of the evolving aerosol size distributions. In this study, we use size-distribution measurements of the OFR and an aerosol microphysics model to learn about size-dependent processes in the OFR. Specifically, we use OFR exposures between 0.09 and 0.9 equivalent days of OH aging from the 2011 BEACHON-RoMBAS and GoAmazon2014/5 field campaigns. We use simulations in the TOMAS (TwO-Moment Aerosol Sectional) microphysics box model to constrain the following parameters in the OFR: (1) the rate constant of gas-phase functionalization reactions of organic compounds with OH, (2) the rate constant of gas-phase fragmentation reactions of organic compounds with OH, (3) the reactive uptake coefficient for heterogeneous fragmentation reactions with OH, (4) the nucleation rate constants for three different nucleation schemes, and (5) an effective accommodation coefficient that accounts for possible particle diffusion limitations of particles larger than 60nm in diameter. We find the best model-to-measurement agreement when the accommodation coefficient of the larger particles (Dp&gt;60nm) was 0.1 or lower (with an accommodation coefficient of 1 for smaller particles), which suggests a diffusion limitation in the larger particles. When using these low accommodation-coefficient values, the model agrees with measurements when using a published H2SO4-organics nucleation mechanism and previously published values of rate constants for gas-phase oxidation reactions. Further, gas-phase fragmentation was found to have a significant impact upon the size distribution, and including fragmentation was necessary for accurately simulating the distributions in the OFR. The model was insensitive to the value of the reactive uptake coefficient on these aging timescales. Monoterpenes and isoprene could explain 24%-95% of the observed change in total volume of aerosol in the OFR, with ambient semivolatile and intermediate-volatility organic compounds (S/IVOCs) appearing to explain the remainder of the change in total volume. These results provide support to the mass-based findings of previous OFR studies, give insight to important size-distribution dynamics in the OFR, and enable the design of future OFR studies focused on new particle formation and/or microphysical processes. © 2018 Author(s)."
"57201138610;57203034911;57202057397;55418157600;7201465504;57199224578;55433597600;57202061114;57202057068;36987542300;55440121900;7006595513;6602954113;","Experimental investigation of variations in morphology, composition and mixing-state of boundary layer aerosol: A balloon based study over urban environment (New Delhi)",2018,"10.1016/j.atmosenv.2018.04.053","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047017709&doi=10.1016%2fj.atmosenv.2018.04.053&partnerID=40&md5=b0cc714318be3cdbabeb6d37bff63fcd","The morphology, composition, and complex mixing states of aerosol are extremely important physico-chemical properties which are the major inputs to the optical/radiative models. Though, ground based observations of the said properties are abundant but the vertical profiles of the same are very much limited throughout the globe. The information on the vertical heterogeneity of the aforementioned properties over a polluted environment like Delhi will be very helpful to develop a better understanding of the thermodynamics of the lower atmosphere. In present study, we carried out a tethered balloon based field campaign in National Physical Laboratory (28° 38′ 10″ N, 77° 10′ 17″ E) from 21 to 27 February 2014 to explore the vertical distribution of the said properties. Based on the microscopic observations, the bubbly shaped sulfate particles number percentage is less (5%) on the ground, abundant (49%) on altitude <350 m and nearly absent on altitude >350 m. At 500 m altitude, particles were majorly of spiked shape with elongated dimension ∼ 3-4 μm. The number percentage of the aged fractals has been found to increase by 4% in the 100-350 m range against the ground observations. Based on the bulk composition of non-carbonaceous species, at 200 m altitude, we observed significant amount (74%) of the oxides of sulfur compared to that of ground observations (30%) that could be due to temperature inversion and air parcel movement from IGP (Indo Gangetic Plain). Various core-shell type particle configurations have been observed at different altitudes. At 200 m altitude, particles were majorly aged with anionic species (like S, Cl and HSO4) and cationic species (like C2H5). The bulk and individual particle level data generated over Delhi environment in this experiment may improve our understanding of boundary layer aerosol and could provide the scientific insights of their probable effects on low level cloud formation. © 2018 Elsevier Ltd"
"6506537159;56548748900;57201609270;35584010200;8247122100;","Joint synoptic and cloud variability over the northeast Atlantic near the Azores",2018,"10.1175/JAMC-D-17-0211.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049204478&doi=10.1175%2fJAMC-D-17-0211.1&partnerID=40&md5=7c5a196121a51d9fd62eb75c75720520","Marine boundary layer clouds are modified by processes at different spatial and temporal scales. To isolate the processes governing aerosol-cloud-precipitation interactions, multiday synoptic variability of the environment must be accounted for. Information on the location of low clouds relative to the ridge-trough pattern gives insight into how cloud properties vary as a function of environmental subsidence and stability. The technique of self-organizing maps (SOMs) is employed to objectively classify the 500-hPa geopotential height patterns for 33 years of reanalysis fields (ERA-Interim) into pretrough, trough, posttrough, ridge, and zonal-flow categories. The SOM technique is applied to a region of prevalent marine low cloudiness over the eastern North Atlantic Ocean that is centered on the Azores island chain, the location of a long-term U.S. Department of Energy observation site. The Azores consistently lie in an area of substantial variability in synoptic configuration, thermodynamic environment, and cloud properties. The SOM method was run in two ways to emphasize multiday and seasonal variability separately. Over and near the Azores, there is an east-to-west sloshing back and forth of the western edge of marine low clouds associated with different synoptic states. The different synoptic states also exhibit substantial north-south variability in the position of high clouds. For any given month of the year, there is large year-to-year variability in the occurrence of different synoptic states. Hence, estimating the climatological behavior of clouds from short-term field campaigns has large uncertainties. This SOM approach is a robust method that is broadly applicable to characterizing synoptic regimes for any location. © 2018 American Meteorological Society."
"55718206700;22234129400;36054921000;7202772927;36868795400;35325977100;57196115458;7403577184;7405489798;","Evolution of Precipitation Structure During the November DYNAMO MJO Event: Cloud-Resolving Model Intercomparison and Cross Validation Using Radar Observations",2018,"10.1002/2017JD027775","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045835676&doi=10.1002%2f2017JD027775&partnerID=40&md5=ca545b4ade160956d9948c262548969f","Evolution of precipitation structures are simulated and compared with radar observations for the November Madden-Julian Oscillation (MJO) event during the DYNAmics of the MJO (DYNAMO) field campaign. Three ground-based, ship-borne, and spaceborne precipitation radars and three cloud-resolving models (CRMs) driven by observed large-scale forcing are used to study precipitation structures at different locations over the central equatorial Indian Ocean. Convective strength is represented by 0-dBZ echo-top heights, and convective organization by contiguous 17-dBZ areas. The multi-radar and multi-model framework allows for more stringent model validations. The emphasis is on testing models' ability to simulate subtle differences observed at different radar sites when the MJO event passed through. The results show that CRMs forced by site-specific large-scale forcing can reproduce not only common features in cloud populations but also subtle variations observed by different radars. The comparisons also revealed common deficiencies in CRM simulations where they underestimate radar echo-top heights for the strongest convection within large, organized precipitation features. Cross validations with multiple radars and models also enable quantitative comparisons in CRM sensitivity studies using different large-scale forcing, microphysical schemes and parameters, resolutions, and domain sizes. In terms of radar echo-top height temporal variations, many model sensitivity tests have better correlations than radar/model comparisons, indicating robustness in model performance on this aspect. It is further shown that well-validated model simulations could be used to constrain uncertainties in observed echo-top heights when the low-resolution surveillance scanning strategy is used. ©2018. American Geophysical Union. All Rights Reserved."
"57201193898;7201798916;7004174939;57194868290;36169987900;36054514100;","In situ measurements of angular-dependent light scattering by aerosols over the contiguous United States",2018,"10.5194/acp-18-3737-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043792314&doi=10.5194%2facp-18-3737-2018&partnerID=40&md5=7136e88a414256c4adb7db205edb1736","This work provides a synopsis of aerosol phase function (F11) and polarized phase function (F12) measurements made by the Polarized Imaging Nephelometer (PI-Neph) during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Deep Convection Clouds and Chemistry (DC3) field campaigns. In order to more easily explore this extensive dataset, an aerosol classification scheme is developed that identifies the different aerosol types measured during the deployments. This scheme makes use of ancillary data that include trace gases, chemical composition, aerodynamic particle size and geographic location, all independent of PI-Neph measurements. The PI-Neph measurements are then grouped according to their ancillary data classifications and the resulting scattering patterns are examined in detail. These results represent the first published airborne measurements of F11and -F12=F11 for many common aerosol types. We then explore whether PI-Neph light-scattering measurements alone are sufficient to reconstruct the results of this ancillary data classification algorithm. Principal component analysis (PCA) is used to reduce the dimensionality of the multi-Angle PI-Neph scattering data and the individual measurements are examined as a function of ancillary data classification. Clear clustering is observed in the PCA score space, corresponding to the ancillary classification results, suggesting that, indeed, a strong link exists between the angular-scattering measurements and the aerosol type or composition. Two techniques are used to quantify the degree of clustering and it is found that in most cases the results of the ancillary data classification can be predicted from PI-Neph measurements alone with better than 85ĝ€-% recall. This result both emphasizes the validity of the ancillary data classification as well as the PI-Neph's ability to distinguish common aerosol types without additional information. © Author(s) 2018."
"57200650233;56989640500;21935606200;25721586700;56724696200;","Vertical Structure and Radiative Forcing of Monsoon Clouds Over Kanpur During the 2016 INCOMPASS Field Campaign",2018,"10.1002/2017JD027759","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042074383&doi=10.1002%2f2017JD027759&partnerID=40&md5=c45fc3b104635566caa5528353010f34","An overview of cloud vertical structure (CVS) and cloud radiative forcing (CRF) during Indian summer monsoon is obtained over Kanpur, through observations made during the Interaction of Convective Organisation and Monsoon Precipitation, Atmosphere, Surface and Sea field campaign of 2016. Associations of CVS parameters with CRF at surface and top of atmosphere (TOA) are also investigated. One hundred thirty-seven radiosondes were launched at Indian Institute of Technology Kanpur, between 5 and 28 July 2016. CVS is determined using an algorithm that identifies cloud layers from vertical profiles of relative humidity, with altitude-dependent relative humidity thresholds. CVS is analyzed by separating the campaign period on the basis of presence and absence of depressions/low-pressure systems. Compared to nondepression periods, low-pressure events showed significant difference in all CVS and CRF parameters except cloud top height. CVS was multilayered in ∼75% launches, with deep, mixed-phase clouds being present in ∼70% launches. CRF was calculated from clear-sky measurements and TOA observations from Clouds and the Earth's Radiant Energy System satellite retrievals, and surface measurements. A net cooling effect was found overall, with instantaneous shortwave CRF (mean values of −95.92 and −101.89 W/m2 at surface and TOA, respectively) dominating longwave cloud radiative forcing (LWCRF) (mean values of 15.33 and 66.55 W/m2 at surface and TOA, respectively). Results suggest that shortwave CRF depends on total depth of cloud layers and is independent of cloud altitude, whereas LWCRF depends on both depth and vertical location of cloud layers, with base and top heights regulating LWCRF at surface and TOA, respectively. ©2018. American Geophysical Union. All Rights Reserved."
"57191329693;7401796996;8629713500;7006783796;24322892500;6506827279;56898950300;56612092200;","Comparisons of Ice Water Path in Deep Convective Systems Among Ground-Based, GOES, and CERES-MODIS Retrievals",2018,"10.1002/2017JD027498","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041621394&doi=10.1002%2f2017JD027498&partnerID=40&md5=b0eb40ea4c3c99ff84e13158e1e03858","Retrievals of convective cloud microphysical properties based on passive satellite imagery are difficult. To help quantify their uncertainties, ice water paths (IWPs) retrieved from the NASA Clouds and the Earth's Radiant Energy System project using Geostationary Operational Environmental Satellite (GOES) and Terra/Aqua MODerate-resolution Imaging Spectroradiometer observations are compared with IWPs retrieved from Next-Generation Radar (NEXRAD) observations over a large domain (32°N to 40°N and 105°W to 91°W) during the 2011 Midlatitude Continental Convective Clouds Experiment field campaign. Based on comparisons of pixel-level (4 km × 4 km) daytime IWP retrievals from NEXRAD and GOES, it is found that NEXRAD- and GOES-retrieved mean IWPs are 2.03 and 1.83 kg m−2, respectively, for ice-phase cloud in thick anvil area. Their mean difference of 0.20 kg m−2 (with 95% confidence interval: 0.14–0.26 kg m−2) is within the uncertainty of NEXRAD retrievals. However, the low correlation between pixel-to-pixel comparisons indicates a large variation in GOES-retrieved IWP. For mixed-phase clouds in thick anvil areas, in addition to IWPs, total water paths (TWPs, sum of ice and liquid water path) are estimated with aid of aircraft measurements for NEXRAD retrievals and corrected using a TWP parameterization for GOES retrievals. The mean values of estimated TWPs from NEXRAD (corrected using aircraft in situ measurements) and GOES are similar. GOES and Clouds and the Earth's Radiant Energy System-MODerate-resolution Imaging Spectroradiometer-retrieved IWPs/TWPs generally do not exceed 5 kg m−2. Large differences and low correlations exist between satellite and NEXRAD retrievals in stratiform rain areas. Possible reasons for the differences between retrievals are discussed. ©2018. American Geophysical Union. All Rights Reserved."
"7102423967;7401796996;8629713500;","Aerosol properties and their impacts on surface CCN at the ARM Southern Great Plains site during the 2011 Midlatitude Continental Convective Clouds Experiment",2018,"10.1007/s00376-017-7033-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040333285&doi=10.1007%2fs00376-017-7033-2&partnerID=40&md5=24fa03105ccc16134e15abc73695ef32","Aerosol particles are of particular importance because of their impacts on cloud development and precipitation processes over land and ocean. Aerosol properties as well as meteorological observations from the Department of Energy Atmospheric Radiation Measurement (ARM) platform situated in the Southern Great Plains (SGP) are utilized in this study to illustrate the dependence of continental cloud condensation nuclei (CCN) number concentration (NCCN) on aerosol type and transport pathways. ARM-SGP observations from the 2011 Midlatitude Continental Convective Clouds Experiment field campaign are presented in this study and compared with our previous work during the 2009–10 Clouds, Aerosol, and Precipitation in the Marine Boundary Layer field campaign over the current ARM Eastern North Atlantic site. Northerly winds over the SGP reflect clean, continental conditions with aerosol scattering coefficient (σsp) values less than 20 Mm−1 and NCCN values less than 100 cm−3. However, southerly winds over the SGP are responsible for the observed moderate to high correlation (R) among aerosol loading (σsp &lt; 60 Mm−1) and NCCN, carbonaceous chemical species (biomass burning smoke), and precipitable water vapor. This suggests a common transport mechanism for smoke aerosols and moisture via the Gulf of Mexico, indicating a strong dependence on air mass type. NASA MERRA-2 reanalysis aerosol and chemical data are moderately to highly correlated with surface ARM-SGP data, suggesting that this facility can represent surface aerosol conditions in the SGP, especially during strong aerosol loading events that transport via the Gulf of Mexico. Future long-term investigations will help to understand the seasonal influences of air masses on aerosol, CCN, and cloud properties over land in comparison to over ocean. © 2018, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature."
"56031356000;7404493635;6602659336;56614955700;6603837066;55913351000;57203297366;7004554762;7005412075;15071316400;50961342600;14049230500;57203474131;24346627600;","The convection, aerosol, and synoptic-effects in the tropics (CAST) experiment: Building an understanding of multiscale impacts on caribbean weather via field campaigns",2017,"10.1175/BAMS-D-16-0192.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028878503&doi=10.1175%2fBAMS-D-16-0192.1&partnerID=40&md5=216415e84f1cba8b96a02ca937c73a4b","The necessity to improve observational capabilities and to better understand local convective processes using western observations led to the Convection, Aerosol, and Synoptic-Effects in the Tropics (CAST) campaign. CAST was conducted by researchers from multiple institutions including the University. Three CAST phases were scheduled to monitor atmospheric conditions in western Puerto Rico during three of its distinct seasons including the midsummer drought, the dry season, and the early rainfall season. Supplemental CAST instrumentation included up to twice-daily radiosonde launches, three high-resolution radars, a ceilometer, a disdrometer, soil moisture sensors, and an aerosol speciation sampler, all on the western side of the island. The disdrometer, soil moisture sensors, and ceilometer ran continuously. To ensure optimal radiosonde launch times, NWS forecasts and weather maps, along with aerosol optical thickness (AOT) forecasts from the National Aeronautics and Space Administration (NASA) Goddard Earth Observing System (GEOS-5) model, were analyzed to ensure that a range of conditions including low and high AOT for dry and wet days were sampled. CAST also provides a basis for setting up modeling experiments centered around some of the more extreme convective events occurring during the experiment. The incorporation of a cloud-resolving model will allow us to further investigate multiscale interactions between large-and local-scale processes and zoom in on their effects on island convection and precipitation."
"57140160700;7005659847;35621058500;7202141884;7003351429;57205842560;7006577245;7004607037;7003469326;7004494400;7005899926;37099534700;40661065000;56212055700;35568326100;57191473265;6701705691;55192470800;7004177770;57148462400;14066601400;55951906300;7102790108;7102113229;7101973570;6603698240;6602109913;8387523500;8562497500;7004307916;55053339600;8527523100;57198369516;","Spatio-temporal monitoring by ground-based and air- and space-borne lidars of a moderate Saharan dust event affecting southern Europe in June 2013 in the framework of the ADRIMED/ChArMEx campaign",2017,"10.1007/s11869-016-0447-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009274876&doi=10.1007%2fs11869-016-0447-7&partnerID=40&md5=bcf29e04a183c3569e9653fcede67c81","During the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the Mediterranean region) special observation period (SOP-1a), conducted in June 2013 in the framework of the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) project, a moderate Saharan dust event swept the Western and Central Mediterranean Basin (WCMB) from west to east during a 9-day period between 16 and 24 June. This event was monitored from the ground by six EARLINET/ACTRIS (European Aerosol Research Lidar Network/Aerosols, Clouds, and Trace gases Research Infrastructure Network) lidar stations (Granada, Barcelona, Naples, Potenza, Lecce and Serra la Nave) and two ADRIMED/ChArMEx lidar stations specially deployed for the field campaign in Cap d’en Font and Ersa, in Minorca and Corsica Islands, respectively. The first part of the study shows the spatio-temporal monitoring of the dust event during its transport over the WCMB with ground-based lidar and co-located AERONET (Aerosol Robotic Network) Sun-photometer measurements. Dust layer optical depths, Ångström exponents, coarse mode fractions, linear particle depolarization ratios (LPDRs), dust layer heights and the dust radiative forcing estimated in the shortwave (SW) and longwave (LW) spectral ranges at the bottom of the atmosphere (BOA) and at the top of the atmosphere (TOA) with the Global Atmospheric Model (GAME), have been used to characterize the dust event. Peak values of the AERONET aerosol optical depth (AOD) at 440 nm ranged between 0.16 in Potenza and 0.37 in Cap d’en Font. The associated Ångström exponent and coarse mode fraction mean values ranged from 0.43 to 1.26 and from 0.25 to 0.51, respectively. The mineral dust produced a negative SW direct radiative forcing at the BOA ranging from −56.9 to −3.5 W m−2. The LW radiative forcing at the BOA was positive, ranging between +0.3 and +17.7 W m-2. The BOA radiative forcing estimates agree with the ones reported in the literature. At the TOA, the SW forcing varied between −34.5 and +7.5 W m−2. In seven cases, the forcing at the TOA resulted positive because of the aerosol strong absorbing properties (0.83 &lt; single-scattering albedo (SSA) &lt; 0.96). The multi-intrusion aspect of the event is examined by means of air- and space-borne lidar measurements, satellite images and back trajectories. The analysis reported in this paper underline the arrival of a second different intrusion of mineral dust observed over southern Italy at the end of the considered period which probably results in the observed heterogeneity in the dust properties. © 2017, Springer Science+Business Media Dordrecht."
"7405489798;7103201242;","CINDY/DYNAMO field campaign: Advancing our understanding of MJO initiation",2017,"10.1142/9789813200913_0027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020264539&doi=10.1142%2f9789813200913_0027&partnerID=40&md5=949defdef19a3976a1bca385a2582beb","An international field campaign CINDY/DYNAMO took place in the Indian Ocean and its surrounding regions during October 2011-March 2012. The main goal of the field campaign was to collect observations that are needed for advancing our understanding and forecast of MJO initiation over the Indian Ocean. Three scientific hypotheses on interaction between convection and its environmental moisture, evolution in cloud population, and air-sea interaction were proposed to guide the design and operation of the field campaign. Unprecedented data were collected by numerous instruments of advanced technology from ground, airplanes, ships, moorings and other platform. These data cover detailed processes through all stages of convective initiation of three very different MJO events. Field observations were released for public use one year after the completion of the field campaign. Studies using these observations have increasingly emerged. These studies confirmed some existing knowledge, challenge some well-accepted paradigms, and reveal new phenomena that motivate novel thinking and approaches to solve the puzzle of MJO initiation. © 2017 World Scientific Publishing Co. Pte. Ltd."
"56976440200;6508047932;57189089842;7006377579;7006235542;7201787800;21933618400;7005941217;","Microphysical Properties of Ice Crystal Precipitation and Surface-Generated Ice Crystals in a High Alpine Environment in Switzerland",2017,"10.1175/JAMC-D-16-0060.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013168350&doi=10.1175%2fJAMC-D-16-0060.1&partnerID=40&md5=7a255ad57bc771027353d477e741a426","During the Cloud and Aerosol Characterization Experiment (CLACE) 2013 field campaign at the High Altitude Research Station Jungfraujoch, Switzerland, optically thin pure ice clouds and ice crystal precipitation were measured using holographic and other in situ particle instruments. For cloud particles, particle images, positions in space, concentrations, and size distributions were obtained, allowing one to extract size distributions classified by ice crystal habit. Small ice crystals occurring under conditions with a vertically thin cloud layer above and a stratocumulus layer approximately 1 km below exhibit similar properties in size and crystal habits as Antarctic/Arctic diamond dust. Also, ice crystal precipitation stemming from midlevel clouds subsequent to the diamond dust event was observed with a larger fraction of ice crystal aggregates when compared with the diamond dust. In another event, particle size distributions could be derived from mostly irregular ice crystals and aggregates, which likely originated from surface processes. These particles show a high spatial and temporal variability, and it is noted that size and habit distributions have only a weak dependence on the particle number concentration. Larger ice crystal aggregates and rosette shapes of some hundred microns in maximum dimension could be sampled as a precipitating cirrostratus cloud passed the site. The individual size distributions for each habit agree well with lognormal distributions. Fitted parameters to the size distributions are presented along with the area-derived ice water content, and the size distributions are compared with other measurements of pure ice clouds made in the Arctic and Antarctic. © 2017 American Meteorological Society."
"36552332100;56780353200;6603377859;6603663168;6701653010;","Capabilities of the Johnson SB distribution in estimating rain variables",2016,"10.1016/j.advwatres.2016.09.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992053173&doi=10.1016%2fj.advwatres.2016.09.017&partnerID=40&md5=9a580e39764bf833b4638a11f292c74b","Numerous fields of atmospheric and hydrological sciences require the parametric form of the raindrop size distribution (DSD) to estimate the rainfall rate from radar observables as well as in cloud resolving and weather forecasting models. This study aims to investigate the capability of the Johnson SB distribution (JSB) in estimating rain integral parameters. Specifically, rainfall rate (R), reflectivity factor (Z) and mean mass diameter (Dmass) estimated by JSB are compared with those estimated by a three-parameter Gamma distribution, widely used by radar meteorologists and atmospheric physicists to model natural DSD. A large dataset consisting of more than 155,000 one-minute DSD, from six field campaigns of Ground Validation (GV) program of NASA/JAXA Global Precipitation Measurement mission (GPM), is used to test the performance of both JSB and Gamma distribution. The available datasets cover a wide range of rain regimes because of the field campaigns were carried out in different seasons and locations. Correlation coefficient, bias, root mean square error (RMSE) and fractional standard error (FSE) between estimated and measured integral parameters are calculated to compare the performances of the two distributions. The capability of JSB in estimating the integral parameters, especially R and Z, resulted very close to that of Gamma distribution. In particular, for light precipitation, JSB is superior to Gamma distribution in estimating R with FSE of 11% with respect to values ranging between 25% and 37% about for Gamma. Comparison of the estimated and measured DSDs shows that the JSB distribution reproduces the natural DSD quite accurately. © 2016 Elsevier Ltd"
"55707289500;56363987000;54393349200;7103204204;6603382350;57209490771;7005941217;6603315547;7005174340;","Spectral optical layer properties of cirrus from collocated airborne measurements and simulations",2016,"10.5194/acp-16-7681-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976411534&doi=10.5194%2facp-16-7681-2016&partnerID=40&md5=1acbc51543c0f7fc8dff8665481c7751","Spectral upward and downward solar irradiances from vertically collocated measurements above and below a cirrus layer are used to derive cirrus optical layer properties such as spectral transmissivity, absorptivity, reflectivity, and cloud top albedo. The radiation measurements are complemented by in situ cirrus crystal size distribution measurements and radiative transfer simulations based on the microphysical data. The close collocation of the radiative and microphysical measurements, above, beneath, and inside the cirrus, is accomplished by using a research aircraft (Learjet 35A) in tandem with the towed sensor platform AIRTOSS (AIRcraft TOwed Sensor Shuttle). AIRTOSS can be released from and retracted back to the research aircraft by means of a cable up to a distance of 4 km. Data were collected from two field campaigns over the North Sea and the Baltic Sea in spring and late summer 2013. One measurement flight over the North Sea proved to be exemplary, and as such the results are used to illustrate the benefits of collocated sampling. The radiative transfer simulations were applied to quantify the impact of cloud particle properties such as crystal shape, effective radius reff, and optical thickness τ on cirrus spectral optical layer properties. Furthermore, the radiative effects of low-level, liquid water (warm) clouds as frequently observed beneath the cirrus are evaluated. They may cause changes in the radiative forcing of the cirrus by a factor of 2. When low-level clouds below the cirrus are not taken into account, the radiative cooling effect (caused by reflection of solar radiation) due to the cirrus in the solar (shortwave) spectral range is significantly overestimated. © Author(s) 2016."
"57189000835;57015826100;55519994900;7103158465;56162305900;23991212200;","Sensitivity of summer ensembles of fledgling superparameterized U.S. mesoscale convective systems to cloud resolving model microphysics and grid configuration",2016,"10.1002/2015MS000567","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992305862&doi=10.1002%2f2015MS000567&partnerID=40&md5=4b0648d0e399d45424aa3eb97973d96a","The sensitivities of simulated mesoscale convective systems (MCSs) in the central U.S. to microphysics and grid configuration are evaluated here in a global climate model (GCM) that also permits global-scale feedbacks and variability. Since conventional GCMs do not simulate MCSs, studying their sensitivities in a global framework useful for climate change simulations has not previously been possible. To date, MCS sensitivity experiments have relied on controlled cloud resolving model (CRM) studies with limited domains, which avoid internal variability and neglect feedbacks between local convection and larger-scale dynamics. However, recent work with superparameterized (SP) GCMs has shown that eastward propagating MCS-like events are captured when embedded CRMs replace convective parameterizations. This study uses a SP version of the Community Atmosphere Model version 5 (SP-CAM5) to evaluate MCS sensitivities, applying an objective empirical orthogonal function algorithm to identify MCS-like events, and harmonizing composite storms to account for seasonal and spatial heterogeneity. A five-summer control simulation is used to assess the magnitude of internal and interannual variability relative to 10 sensitivity experiments with varied CRM parameters, including ice fall speed, one-moment and two-moment microphysics, and grid spacing. MCS sensitivities were found to be subtle with respect to internal variability, and indicate that ensembles of over 100 storms may be necessary to detect robust differences in SP-GCMs. These results emphasize that the properties of MCSs can vary widely across individual events, and improving their representation in global simulations with significant internal variability may require comparison to long (multidecadal) time series of observed events rather than single season field campaigns. © 2016. The Authors."
"25647939800;57069790200;9535769800;","An ensemble hindcast of the Madden-Julian oscillation during the CINDY2011/DYNAMO field campaign and influence of seasonal variation of sea surface temperature",2016,"10.2151/jmsj.2015-055","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955131482&doi=10.2151%2fjmsj.2015-055&partnerID=40&md5=ac9b95f58a31c96a26560d5016edf43f","The ensemble hindcast initialized during 12–16 October 2011 is performed using a global cloud-system-resolving model (CSRM) with a horizontal mesh size of approximately 14 km. The ensemble size is five and the duration of each simulation is 60 days. When sea surface temperature (SST) with a realistic time evolution is prescribed, not only the first but also the second Madden-Julian oscillation (MJO) event observed during the CINDY2011/ DYNAMO period emerges in the ensemble mean, although the signal of the second MJO is unsatisfactory in each member. This result leads to a hypothesis that the second MJO is significantly constrained by the prescribed seasonal change of SST. The analyses of the observational data indicate that an MJO favorable environment, in which SST of the southeastern Maritime Continent is higher than that of the Indian Ocean, is established in late November to early December. Humidity in the lower troposphere increases substantially in the southeastern Maritime Continent during the period. A pair of sensitivity tests using a global CSRM clearly shows that the eastward migration of convection during the second MJO is at least partly caused by the climatological seasonal change of SST. The results of this study indicates that it is inappropriate to treat the climatological seasonal change as the background of the MJO during this season, because its timescale is short enough to be comparable with the intraseasonal timescale of the MJO. We provide a perspective that a certain type of the MJO can be regarded as a transition process, responding to the eastward shift of the region of large-scale positive buoyancy production following the warmer SST. © 2015, Meteorological Society of Japan."
"24403494800;57204253860;34881780600;6506328135;","A retrieval of tropical latent heating using the 3D structure of precipitation features",2016,"10.1175/JAMC-D-15-0038.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982847687&doi=10.1175%2fJAMC-D-15-0038.1&partnerID=40&md5=3899daee64bb429d67c236f92d348800","Radar-based latent heating retrievals typically apply a look-up table (LUT) derived from model output to surface rain amounts and rain type to determine the vertical structure of heating. In this study, we develop a method that uses the size characteristics of precipitating systems (i.e., area and mean echo-top height) instead of rain amount to estimate latent heating profiles from radar observations. This technique (named the Convective-Stratiform Area [CSA] algorithm) leverages the relationship between the organization of convective systems and the structure of latent heating profiles and avoids pitfalls associated with retrieving accurate rainfall information from radars and models. The CSA LUTs are based on a high-resolution regional model simulation over the equatorial Indian Ocean. The CSA LUTs show that convective latent heating increases in magnitude and height as area and echo-top heights grow, with a congestus signature of mid-level cooling for less vertically extensive convective systems. Stratiform latent heating varies weakly in vertical structure, but its magnitude is strongly linked to area and mean echo-top heights. The CSA LUT was applied to radar observations collected during the DYNAMO/CINDY2011/AMIE field campaign and the CSA heating retrieval was generally consistent with other measures of heating profiles. The impact of resolution and spatial mismatch between the model and radar grids is addressed and unrealistic latent heating profiles in the stratiform LUT, viz., a low-level heating peak, an elevated melting layer, and net column cooling, were identified. These issues highlight the need for accurate convective-stratiform separations and improvement in PBL and microphysical parameterizations. © 2015 American Meteorological Society."
"57209089003;22136950500;57212901405;8963601100;23098283400;57192236392;57009108900;57188744437;24458137900;","Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley",2015,"10.5194/acpd-15-25021-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952938084&doi=10.5194%2facpd-15-25021-2015&partnerID=40&md5=9b27bfed3785a9f1ad47a90e82229fc9","The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the Valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012-2013, a comprehensive study was carried out to characterize the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs by deploying a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS)-the first such deployment in South Asia. 71 ion peaks (for which measured ambient concentrations exceeded the 2 &sigma; detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the Valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m/&Delta;m > 4200) and temporal resolution (1 min) of the PTR-TOF-MS. The highest average VOC mixing ratios during the measurement period were (in rank order): acetaldehyde (8.8 ppb), methanol (7.4 ppb), acetone (4.2 ppb), benzene (2.7 ppb), toluene (1.5 ppb), isoprene (1.1 ppb), acetonitrile (1.1 ppb), C8-aromatics (∼ 1 ppb), furan (∼ 0.5 ppb), and C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (<I>m/z</I> Combining double low line 69.070) and furan (<I>m/z</I> Combining double low line 69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde (∼ 9 ppb), acetonitrile (∼ 1 ppb) and isoprene (∼ 1 ppb) to be among the highest reported till date. Two ""new"" ambient compounds namely, formamide (<I>m/z</I> Combining double low line 46.029) and acetamide (<I>m/z</I> Combining double low line 60.051), which can photochemically produce isocyanic acid in the atmosphere, are reported in this study along with nitromethane (a tracer for diesel exhaust) which has only recently been detected in ambient studies. Two distinct periods were selected during the campaign for detailed analysis: the first was associated with high wintertime emissions of biogenic isoprene, and the second with elevated levels of ambient acetonitrile, benzene and isocyanic acid from biomass burning activities. Emissions from biomass burning and biomass co-fired brick kilns were found to be the dominant sources for compounds such as propyne, propene, benzene and propanenitrile which correlated strongly with acetonitrile (<I>r</I>2 > 0.7), a chemical tracer for biomass burning. The calculated total VOC OH reactivity was dominated by acetaldehyde (24.0 %), isoprene (20.2 %) and propene (18.7 %), while oxygenated VOCs and isoprene collectively contributed to more than 68 % of the total ozone production potential. Based on known SOA yields and measured ambient concentrations in the Kathmandu Valley, the relative SOA production potential of VOCs were: benzene > naphthalene > toluene > xylenes > monoterpenes > trimethyl-benzenes > styrene > isoprene. The first ambient measurements from any site in South Asia of compounds with significant health effects such as isocyanic acid, formamide, acetamide, naphthalene and nitromethane have been reported in this study. Our results suggest that mitigation of intense wintertime biomass burning activities, in particular point sources such biomass co-fired brick kilns, would be important to reduce the emission and formation of toxic VOCs (such as benzene and isocyanic acid) in the Kathmandu Valley and improve its air quality. © Author(s) 2015."
"35290843900;7406200372;57204587603;55612831900;56898331700;55487543500;7201791739;55613163100;","Chemical characteristics of air masses from different urban and industrial centers in the Huabei region of China",2013,"10.1016/j.atmosenv.2013.01.045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874516804&doi=10.1016%2fj.atmosenv.2013.01.045&partnerID=40&md5=15d4554e10676852459db32e50f72978","North China, or Huabei in Chinese, is one of the most severely polluted regions in China. There are many large, complex and strong emission sources in Beijing, Tianjin and Tangshan (together called Jing-Jin-Tang in Chinese) and other urban and industrial centers in Huabei, and the chemical characteristics of air masses coming from these pollution centers are expected to be quite different. As part of the project ""Influence of Pollution on Aerosols and Cloud Microphysics in North China (IPAC-NC)"", surface ozone and related trace gases were measured at the Xin'an rural station (39.73°N, 117.51°E), located in the central part of larger Jing-Jin-Tang area, during 2 April-16 May 2006. Here we investigate the chemical characteristics and impact of air masses from these different pollution hotspots on the regional distributions of ozone and nitrogen oxides in Huabei, based on measurement data as well as a regional chemical transport model. Simulated reactive nitrogen compounds are attributed to the different emission sources in the Huabei region using the tracer-tagging method implemented in the model. We find that the chemical characteristics of pollution plumes from different urban and industrial centers are rather different. The OPEx, defined as ozone production efficiency of nitrogen oxides (NOx), for general pollution plumes from Beijing, Tianjin, Tangshan and Shijiazhuang are estimated to be 3.35, 2.75, 1.43 and 2.33 mol mol-1, respectively. During the IPAC-NC field campaign period, the Xin'an site was influenced alternatively by air masses from Beijing and Tianjin megacities and the Tangshan industrial area. The estimated OPEx in Beijing, Tianjin and Tangshan air masses arriving at Xin'an are comparable to those in their general pollution plumes. This indicates that air masses from different urban and industrial centers in Huabei also maintain their different chemical characteristics while being transported to the rural areas. © 2013 Elsevier Ltd."
"44261758800;44261675000;6701873414;56982312900;","The Cloud Hunter's problem: An automated decision algorithm to improve the productivity of scientific data collection in stochastic environments",2011,"10.1175/2010MWR3576.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960715029&doi=10.1175%2f2010MWR3576.1&partnerID=40&md5=1b5773c331ee69b4ce3afbe43b0a72bb","A decision algorithm is presented that improves the productivity of data collection activities in stochastic environments. The algorithm was developed in the context of an aircraft field campaign organized to collect data in situ from boundary layer clouds. Required lead times implied that aircraft deployments had to be scheduled in advance, based on imperfect forecasts regarding the presence of conditions meeting specified requirements. Given an overall cap on the number of flights, daily fly/no-fly decisions were taken traditionally using a discussion-intensive process involving heuristic analysis of weather forecasts by a group of skilled human investigators. An alternative automated decision process uses self-organizing maps to convert weather forecasts into quantified probabilities of suitable conditions, together with a dynamic programming procedure to compute the opportunity costs of using up scarce flights from the limited budget. Applied to conditions prevailing during the 2009 Routine ARM Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) campaign of the U.S. Department of Energy's Atmospheric Radiation Measurement Program, the algorithm shows a 21% increase in data yield and a 66% improvement in skill over the heuristic decision process used traditionally. The algorithmic approach promises to free up investigators' cognitive resources, reduce stress on flight crews, and increase productivity in a range of data collection applications. © 2011 American Meteorological Society."
"7403364008;25953950400;","Cold and transition season cloud condensation nuclei measurements in western Colorado",2011,"10.5194/acp-11-4303-2011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955926502&doi=10.5194%2facp-11-4303-2011&partnerID=40&md5=25dfb70b78b43f8cf9edb059db27f5d4","Recent studies have shown that orographic precipitation and the water resources that depend on it in the Colorado Rocky Mountains are sensitive to the variability of the region's aerosols, whether emitted locally or from distant sources. However, observations of cloud droplet nucleating aerosols in western Colorado, climatologically upwind of the Colorado Rocky Mountains, have been limited to a few studies at a single, northern site. To address this knowledge gap, atmospheric aerosols were sampled at a ground site in southwestern Colorado and in low-level north to south transects of the Colorado Western Slope as part of the Inhibition of Snowfall by Pollution Aerosols (ISPA-III) field campaign. Total particle and cloud condensation nuclei (CCN) number concentrations were measured for a 24-day period in Mesa Verde National Park, in September and October 2009. Regression analysis showed a positive relationship between mid-troposphere atmospheric pressure to the west of the site and the total particle count at the ground site, but no similar statistically significant relationship was found for the observed CCN. These data were supplemented with particle and CCN number concentration, as well as particle size distribution measurements collected aboard the King Air platform during December 2009. A CCN closure attempt was performed and suggested that the sampled aerosol may have had a low hygroscopicity that changed little with the large-scale wind direction. Together, the sampled aerosols from these field programs were characteristic of a rural continental environment with CCN number concentrations that varied slowly in time, and little in space along the Western Slope. © 2011 Author(s)."
"36465124400;21933618400;35559590900;7201787800;35224765000;7006235542;7006837187;6603172418;","In situ aerosol measurements taken during the 2007 COPS field campaign at the Hornisgrinde ground site",2011,"10.1002/qj.727","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79952001936&doi=10.1002%2fqj.727&partnerID=40&md5=5d1425831023519dde3f1ea1f84421d7","The Convective and Orographically-induced Precipitation Study (COPS) campaign was conducted during the summer of 2007. A suite of instruments housed at the top of the Hornisgrinde Mountain (1156 m) in the Black Forest region of south-west Germany provided datasets that allow an investigation into the physical, chemical and hygroscopic properties of the aerosol particles sampled during COPS. Organic mass loadings were found to dominate the aerosol composition for the majority of the project, exceeding 8 μg m-3 during a period of high pressure, high temperature, and low wind speed. The ratio of organic:sulphate sub-micron mass concentration exceeds 10:1 during the same time period. Back trajectories show air from this time-frame passing slowly over the local forest and not passing over any local anthropogenic sources. Occasional peaks in nitrate mass loadings were associated with changes in the typical wind direction from south-westerly to north-westerly where air had passed over the Stuttgart region. Size distribution data shows a dominant accumulation-mode when the measurement site was free from precipitation events. A sharp increase in ultrafine particle number concentration was seen during most days commencing around noon. The apparent growth of these particles is associated with an increase in organic mass loading, suggesting condensational growth. For the most part, with the exception of the high pressure period, the aerosol properties recorded during COPS were comparable to previous studies of continental aerosol properties. Copyright © 2011 Royal Meteorological Society Copyright © 2011 Royal Meteorological Society."
"6506328135;","Building blocks of tropical diabatic heating",2010,"10.1175/2010JAS3252.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955574306&doi=10.1175%2f2010JAS3252.1&partnerID=40&md5=6d67e97f49e4c39a4657d827bc55606a","Rotated EOF analyses are used to study the composition and variability of large-scale tropical diabatic heating profiles estimated from eight field campaigns. The results show that the profiles are composed of a pair of building blocks. These are the stratiform heating with peak heating near 400 hPa and a cooling peak near 700 hPa and the convective heating with a heating maximum near 700 hPa. Variations in the contributions of these building blocks account for the evolution of the large-scale heating profile. Instantaneous top-heavy (bottom-heavy) large-scale heating profiles associated with excess of stratiform (convective) heating evolve toward a stationary mean profile due to exponential decay of the excess stratiform (convective) heating. © 2010 American Meteorological Society."
"16068679800;9841756200;6701650121;7004189702;23866122100;","Lightning-produced NO2 observed by two ground-based UV-visible spectrometers at Vanscoy, Saskatchewan in August 2004",2007,"10.5194/acp-7-1683-2007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947636747&doi=10.5194%2facp-7-1683-2007&partnerID=40&md5=41da7b035bef73c3f8f8550344a1294f","Ground-based measurements of ozone and NO2 differential slant columns by the SAOZ (Système d'Analyse par Observations Zénithales) and UT-GBS (University of Toronto Ground-Based Spectrometer) instruments during the MANTRA 2004 field campaign are presented herein. During the afternoon of 28 August, a thunderstorm passed over the instruments, which were installed at Vanscoy, Saskatchewan (52° N, 107° W). Enhanced differential slant columns of ozone and NO2 were observed by both instruments during the storm, with maximum values of two and 25 times the expected clear sky columns, respectively. The enhanced ozone differential slant columns are primarily due to the longer path traversed by the solar radiation caused by multiple scattering inside the thick cloud layer associated with the thunderstorm. The enhanced NO2 columns are partly attributed to NOx production by lightning. Two new methods are used to separate the NO2 enhancements into contributions from the longer path length and production by lightning. Combining the observed excess NO2 with lightning flash data from the Canadian Lightning Detection Network and Environment Canada Doppler radar measurements, the production of NO2 molecules per lightning flash is determined. Using these two methods, the best estimate of the production rate is found to be (7.88±2.52) × 1026 molecules NO2/flash from the UT-GBS and (6.81±2.17) ×1026 molecules NO2/flash from SAOZ. These results are consistent with the range of previous estimates reported in the literature."
"56288754100;15821870100;56211898600;57210538699;7102807964;7102674341;9940368600;7102578937;","Measurements of O3, NO2 and BrO during the INDOEX campaign using ground based DOAS and GOME satellite data",2007,"10.5194/acp-7-283-2007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846345653&doi=10.5194%2facp-7-283-2007&partnerID=40&md5=6daca52b4184f8053180f37f9037c777","The INDian Ocean Experiment (INDOEX) was an international, multi-platform field campaign to measure long-range transport of air masses from South and South-East-(SE) Asia towards the Indian Ocean. During the dry monsoon season between January and March 1999, local measurements were carried out from ground based platforms and were compared with satellite based data. The objective of this study was to characterise stratospheric and tropospheric trace gas amounts in the equatorial region, and to investigate the impact of air pollution at this remote site. For the characterisation of the chemical composition of the outflow from the S-SE-Asian region, we performed ground based dual-axis-DOAS (Differential Optical Absorption Spectroscopy) measurements at the KCO (Kaashidhoo Climate Observatory) in the Maldives (5.0° N, 73.5° E). The measurements were conducted using two different observation modes (off-axis and zenith-sky). This technique allows the separation of the tropospheric and stratospheric columns for different trace gases like O3 and NO 2. These dual-axis DOAS data were compared with O3-sonde measurements performed at KCO and satellite based GOME (Global Ozone Measuring Experiment) data during the intensive measuring phase of the INDOEX campaign in February and March 1999. From GOME observations, tropospheric and stratospheric columns for O3 and NO2 were retrieved. In addition, the analysis of the O3-sonde measurements allowed the determination of the tropospheric O3 amount. The comparison shows that the results of all three measurement systems agree within their error limits. During the INDOEX campaign, mainly background conditions were observed, but in a single case an increase of tropospheric NO2 during a short pollution event was observed from the ground and the impact on the vertical columns was calculated. GOME measurements showed evidence for small tropospheric contributions to the BrO budget, probably located in the free troposphere and present over long periods of the year. The amounts of BrO have been investigated by the comparison of satellite pixels influenced by high and low cloud conditions based on GOME data which allows the determination of the detection limit of 3.8×10 13molecules cm-2 of tropospheric BrO columns."
"6508029837;7006329853;7006173230;26643054400;8986277400;8412522100;7202463361;6603332962;6603875883;7403948303;7006534847;35396858200;26028515700;57136469800;35405390200;16645347900;8386790800;35406457100;","Nitric acid condensation on ice: 1. Non-HNO3 constituent of NOY condensing on upper tropospheric cirrus particles",2006,"10.1029/2005JD006048","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250877089&doi=10.1029%2f2005JD006048&partnerID=40&md5=3cebab788e53f5b2e16e324a90127e2c","Measurements of NOY condensation on cirrus particles during the SOLVE-I field campaign are analyzed and segregated based on altitude. Significant amounts of NOY were found on the upper tropospheric ice particles; therefore condensation on ice appears to be an important method of NOY removal from the gas phase at the low temperatures of the Scandinavian upper troposphere. For the data set collected on 23 January 2000, NOY condensation on cirrus particles has different properties depending on whether the ice particles are sampled in the upper troposphere, where HNO3 does not dominate NOY, or in the lower stratosphere, where HNO3 does dominate NOY. Nitric acid becomes enriched in the gas phase as NOY condenses on upper tropospheric ice crystals, indicating that a non-HNO3 component of NOY is condensing on upper tropospheric ice particles much faster and at higher concentrations than HNO3 alone on this day. It is unclear which non-HNO3 constituent of NOY is condensing on upper tropospheric ice particles, although N2O5 is the most likely species. This condensation of a non-HNO3 component of NOY is not universal in the upper troposphere but depends on the conditions of the air parcel in which sampling occurred, notably exposure to sunlight. Copyright 2006 by the American Geophysical Union."
"7005941217;7004249622;56494996200;","Chemistry and aerosol measurements on the Geophysika stratospheric research aircraft: The airborne polar experiment",1995,"10.1016/0079-1946(95)00011-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029530419&doi=10.1016%2f0079-1946%2895%2900011-X&partnerID=40&md5=c3d5d3c23d9aa712f01643c9e60ea444","Since the early nineties efforts have been made to transform the Russian high altitude aircraft M-55 Geophysika into a flying laboratory suited for stratospheric research aimed at environmental issues such as ozone depletion, the assessment of the influence of commercial airtraffic on the atmosphere and other topics concerned with upper tropospheric and lower stratospheric physics and chemistry. As a result of these efforts the Airborne Polar Experiment (APE) is presently being planned and prepared (Stefanutti et. al., 1995). The first field campaign with Geophysika is scheduled to take place in the 1996/97 winter season from an airport in northern Sweden or Finland and a southern hemispheric experiment is projected for mid 1997 or mid 1998. © 1995."
"56668200500;23492163200;7006518879;56578584500;56735590500;56655078300;23568273000;7003851395;","Comparing methods for mapping canopy chlorophyll content in a mixed mountain forest using Sentinel-2 data",2020,"10.1016/j.jag.2019.102037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081605717&doi=10.1016%2fj.jag.2019.102037&partnerID=40&md5=dfb398742f3d6d3409aaefe8607a0f0d","The Sentinel-2 Multi-Spectral Imager (MSI) has three spectral bands centered at 705, 740, and 783 nm wavelengths that exploit the red-edge information useful for quantifying plant biochemical traits. This sensor configuration is expected to improve the prediction accuracy of vegetation chlorophyll content. In this work, we assessed the performance of several statistical and physical-based methods in retrieving canopy chlorophyll content (CCC) from Sentinel-2 in a heterogeneous mixed mountain forest. Amongst the algorithms presented in the literature, 13 different vegetation indices (VIs), a non-parametric statistical approach, and two radiative transfer models (RTM) were used to assess the CCC prediction accuracy. A field campaign was conducted in July 2017 to collect in situ measurements of CCC in Bavarian forest national park, and the cloud-free Sentinel-2 image was acquired on 13 July 2017. The leave-one-out cross-validation technique was used to compare the VIs and the non-parametric approach. Whereas physical-based methods were calibrated using simulated data and validated using the in situ reference dataset. The statistical-based approaches, such as the modified simple ratio (mSR) vegetation index and the partial least square regression (PLSR) outperformed all other techniques. As such the modified simple ratio (mSR3) (665, 865) gave the lowest cross-validated RMSE of 0.21 g/m2 (R2 = 0.75). The PLSR resulted in the highest R2 of 0.78, and slightly higher RMSE =0.22 g/m2 than mSR3. The physical-based approach-INFORM inversion using look-up table resulted in an RMSE =0.31 g/m2, and R2 = 0.67. Although mapping CCC using these methods revealed similar spatial distribution patterns, over and underestimation of low and high CCC values were observed mainly in the statistical approaches. Further validation using in situ data from different terrestrial ecosystems is imperative for both the statistical and physical-based approaches' effectiveness to quantify CCC before selecting the best operational algorithm to map CCC from Sentinel-2 for long-term terrestrial ecosystems monitoring across the globe. © 2019"
"9537045600;6603768446;26634569400;36458602300;22980018800;6603431534;","Triple-Frequency Radar Retrievals",2020,"10.1007/978-3-030-24568-9_13","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089067582&doi=10.1007%2f978-3-030-24568-9_13&partnerID=40&md5=6950649e00e2e67bf5a5b46e93760ca7","With triple frequency radars becoming more and more popular both at ground-based facilities and on airborne platforms and with the prospect of a space mission with a triple-frequency radar payload on the horizon, triple-frequency radar retrievals are becoming fertile areas of active research. In this chapter the benefits and potentials of a triple-frequency radar approach for retrieving rain and ice microphysics will be discussed first on a theoretical basis and then demonstrated for a stratiform case study extracted from the OLYMPEX field campaign with Ku-Ka-W band radar observations. Challenges and recommendations for future work are included in the chapter. © 2020, Springer Nature Switzerland AG."
"56195639700;7409080503;","Episodes of Warm-Air Advection Causing Cloud-Surface Decoupling During the MARCUS",2019,"10.1029/2019JD030835","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075431120&doi=10.1029%2f2019JD030835&partnerID=40&md5=a427e7c259132e9320b0bbdfe2c1df7f","It has been known for decades that advection of a cloud-topped marine boundary layer (CTBL) over warmer sea surface causes the stratification (or decoupling) of the CTBL via the entrainment feedback, a mechanism commonly known as “deepening-warming” decoupling that is typical in subtropics. This study focuses on the opposite direction of advection, that is, low-level warm air advection (LLWAA), and its impacts on the decoupling degree of a CTBL. Our hypothesis is that LLWAA stabilizes a CTBL, causing a decoupling of the CTBL. It is tested for three LLWAA episodes observed during the Measurements of Aerosols, Radiation, and CloUds over the Southern Ocean (MARCUS) field campaign between the Hobart (43°S, 147°E), Australia, and several Antarctic coast stations. By synthesizing the shipborne measurements of CTBL structure, Himawari-8 satellite imagery of cloud fields, and reanalysis of meteorological field, four common characteristics of CTBLs under the LLWAA are found: (1) CTBLs are highly stratified to the extent that penetrations of cumulus into main temperature inversions, which are common for subtropical decoupled CTBLs, do not exist; (2) sea surface temperature is 1–2 K lower than the near-surface air temperature; (3) clouds manifest stratiform with lifetime as long as several tens of hours; and (4) they locate in warm sectors of middle-latitude cyclones. Possible mechanisms for the maintenance of decoupled clouds under LLWAA are discussed in terms of dynamic and thermodynamic factors. Lapse rates of the decoupled CTBLs are markedly lower than those commonly used for passive satellite estimation of cloud top heights. ©2019. American Geophysical Union. All Rights Reserved."
"57211745320;6602681732;35572096100;","Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar",2019,"10.5194/amt-12-5897-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074903457&doi=10.5194%2famt-12-5897-2019&partnerID=40&md5=d3af2f42e84919bea94b833e071b2588","This paper presents a methodology for ice water content (IWC) retrieval from a dual-polarization side-looking X-band airborne radar. Measured IWC from aircraft in situ probes is weighted by a function of the radar differential reflectivity (Zdr) to reduce the effects of ice crystal shape and orientation on the variation in IWC-specific differential phase (Kdp) joint distribution. A theoretical study indicates that the proposed method, which does not require a knowledge of the particle size distribution (PSD) and number density of ice crystals, is suitable for high-ice-water-content (HIWC) regions in tropical convective clouds. Using datasets collected during the High Altitude Ice Crystals-High Ice Water Content (HAIC-HIWC) international field campaign in Cayenne, French Guiana (2015), it is shown that the proposed method improves the estimation bias by 35% and increases the correlation by 4% on average, compared to the method using specific differential phase (Kdp) alone. © 2019 Journal of Education and Health Promotion."
"57202258494;8309699900;7202948585;57202258793;57195233365;7103000184;","Observed below-Cloud and Cloud Interstitial Submicron Aerosol Chemical and Physical Properties at Whiteface Mountain, New York, during August 2017",2019,"10.1021/acsearthspacechem.9b00117","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072233776&doi=10.1021%2facsearthspacechem.9b00117&partnerID=40&md5=220b7f3f91cee43ec029ae542499a0d1","A pilot study took place at Whiteface Mountain (WFM) in the Adirondacks of upstate New York during the summer of 2017 to evaluate the chemical processing of aerosol within clouds. Below-cloud and cloud interstitial submicron aerosols were characterized in real-time using an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and other instruments deployed via the Atmospheric Sciences Research Center (ASRC) sprinter van mobile laboratory. The primary observation is a dominance of organic aerosol mass, averaging 66%-78% of PM2.5 during urban-influenced periods and 83-93% during biogenic-influenced periods, in stark contrast to observations in the northeastern U.S. in past decades when sulfate dominated the aerosol mass. The observations also show chemical differences between the below-cloud layer, the transition layer (just below-cloud), and the in-cloud layer. Comparison between these layers revealed enhanced inorganic nitrate in interstitial aerosol sampled in the transition and in-cloud layers compared to the below-cloud aerosol. Enhanced particle nitrate mass concentrations were more significant during urban influenced cloud events than biogenic influenced ones. The below-cloud and transition layer aerosols were characterized by similar bimodal number and mass size distributions, and when entrained into the cloud, aerosols with number mean dry diameters of &gt; ∼50 nm were incorporated into cloud droplets, suggesting that cloud supersaturations at WFM can be quite high (&gt;0.6%). The organic component of the interstitial aerosols in the transition and in-cloud layers is slightly less oxidized than the below-cloud aerosol. The hygroscopicity parameter (κ), as determined from size-resolved cloud condensation nuclei (CCN) measurements at water vapor supersaturations ranging from 0.23% to 0.78%, was 0.13-0.19 throughout the majority of the pilot study. Exceptions were two of the five urban-influenced periods (with κ values of 0.27-0.33) and at the lowest supersaturation (0.23%) for two of the three biogenic-influenced periods (with κ values of 0.23-0.25), the latter of which may be attributed to greater accumulation of soluble aerosol mass during aqueous/cloud processing of larger particles. The hygroscopicity of the organic component was estimated to range from 0.08 to 0.22, and was well correlated with the organic oxidation state. The below-cloud and cloud interstitial aerosol observations shown here comprise an important part of the 2017 pilot study at WFM. These observations also provide a baseline for future intensive field campaigns focused on cloud processing at WFM, which will ultimately inform atmospheric models to better simulate cloud processing in the northeastern U.S in comparison to other biogenic-dominated locations. © 2019 American Chemical Society."
"18635289400;57191845088;55870609300;55233910100;7101707186;57218359395;7003729315;15047918700;55372899300;56061814400;6602137800;57202922977;7003359002;7101899854;","Two decades observing smoke above clouds in the south-eastern Atlantic Ocean: Deep Blue algorithm updates and validation with ORACLES field campaign data",2019,"10.5194/amt-12-3595-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068435250&doi=10.5194%2famt-12-3595-2019&partnerID=40&md5=0a3d8fef7aa69a8f921c0782654a9cc9","This study presents and evaluates an updated algorithm for quantification of absorbing aerosols above clouds (AACs) from passive satellite measurements. The focus is biomass burning in the south-eastern Atlantic Ocean during the 2016 and 2017 ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign deployments. The algorithm retrieves the above-cloud aerosol optical depth (AOD) and underlying liquid cloud optical depth and is applied to measurements from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS), and Visible Infrared Imaging Radiometer Suite (VIIRS) from 1997 to 2017. Airborne NASA Ames Spectrometers for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) and NASA Langley High Spectral Resolution Lidar 2 (HSRL2) data collected during ORACLES provide important validation for spectral AOD for MODIS and VIIRS; as the SeaWiFS mission ended in 2010, it cannot be evaluated directly. The 4STAR and HSRL2 comparisons are complementary and reveal performance generally in line with uncertainty estimates provided by the optimal estimation retrieval framework used. At present the two MODIS-based data records seem the most reliable, although there are differences between the deployments, which may indicate that the available data are not yet sufficient to provide a robust regional validation. Spatiotemporal patterns in the data sets are similar, and the time series are very strongly correlated with each other (correlation coefficients from 0.95 to 0.99). Offsets between the satellite data sets are thought to be chiefly due to differences in absolute calibration between the sensors. The available validation data for this type of algorithm are limited to a small number of field campaigns, and it is strongly recommended that such airborne measurements continue to be made, both over the southern Atlantic Ocean and elsewhere. © Author(s) 2019."
"57191089524;7006788343;","Numerical Simulations of an Inversion Fog Event in the Salt Lake Valley during the MATERHORN-Fog Field Campaign",2019,"10.1007/s00024-018-1770-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064890696&doi=10.1007%2fs00024-018-1770-8&partnerID=40&md5=88b28f7315e530333f3154723f3b562f","An advanced research version of the Weather Research and Forecasting (WRF) Model is employed to simulate a wintertime inversion fog event in the Salt Lake Valley during the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) field campaign during January 2015. Simulation results are compared to observations obtained from the field program. The sensitivity of numerical simulations to available cloud microphysical (CM), planetary boundary layer (PBL), radiation, and land surface models (LSMs) is evaluated. The influence of differing visibility algorithms and initialization times on simulation results is also examined. Results indicate that the numerical simulations of the fog event are sensitive to the choice of CM, PBL, radiation, and LSM as well as the visibility algorithm and initialization time. Although the majority of experiments accurately captured the synoptic setup environment, errors were found in most experiments within the boundary layer, specifically a 3° warm bias in simulated surface temperatures compared to observations. Accurate representation of surface and boundary layer variables are vital in correctly predicting fog in the numerical model. © 2018, Springer International Publishing AG, part of Springer Nature."
"57207622911;6506537159;57203504470;56518420000;7102743829;36097134700;","Assessing the mechanisms governing the daytime evolution of marine stratocumulus using large-eddy simulation",2019,"10.1002/qj.3469","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062657145&doi=10.1002%2fqj.3469&partnerID=40&md5=a06cbd5a13bd289f9d00da31bd3b0921","Large-eddy simulation (LES) output for a case of thin stratocumulus off the coast of California is examined in a mixed-layer analysis framework to identify the specific mechanisms responsible for governing the evolution of the cloud system. An equation for cloud-base height tendency isolates the individual cloud-modulating mechanisms that control the evolution of boundary-layer liquid-water static energy (Sl) and total water mixing ratio (qT). With a suitable spin-up procedure, the control simulation performs admirably compared with observed estimates of liquid water content, vertical velocity variance, and radiative fluxes sampled during an aircraft field campaign. Investigation of the cloud response to various environmental forcing scenarios was addressed through a suite of sensitivity simulations, including variations in subsidence velocity, surface fluxes, wind shear near the inversion, and radiative forcing. In the control simulation, rising cloud-base tendencies are associated with entrainment warming/drying and short-wave absorption, whereas lowering cloud-base tendencies are driven by long-wave cooling. Even in the presence of substantial afternoon solar heating, entrainment fluxes remained active. The thin cloud demonstrated unexpected resiliency, with mixed-layer analysis indicating that, as the short-wave flux decreases later in the afternoon, the relative contribution of long-wave cooling often becomes large enough to offset entrainment warming/drying and result in a reversal of cloud-base tendency. The evolution of cloud-base tendency is found to be insensitive to the net radiative flux divergence for most of the simulations (liquid water path ranging from ~10–50 g/m2). Error analysis in comparison with LES Sl and qT budgets suggests that our method of entrainment flux calculation could be improved by a more complete understanding of entrainment-layer physics. © 2018 Royal Meteorological Society"
"8612873400;7102866124;35858291700;57201352108;","Global Positioning System precipitable water vapour (GPS-PWV) jumps before intense rain events: A potential application to nowcasting",2019,"10.1002/met.1735","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056629748&doi=10.1002%2fmet.1735&partnerID=40&md5=46fd3edabb26605c2661969b04669600","A rapid increase in atmospheric water vapour is a fundamental ingredient for many intense rainfall events. High-frequency precipitable water vapour (PWV) estimates (1 min) from a Global Positioning System (GPS) meteorological site are evaluated in this paper for intense rainfall events during the CHUVA Vale field campaign in Brazil (November and December 2011) in which precipitation events of differing intensities and spatial dimensions, as observed by an X-band radar, were explored. A sharp increase in the GPS-PWV before the more intense events was found and termed GPS-PWV “jumps.” These jumps are probably associated with water vapour convergence and the continued formation of cloud condensate and precipitation particles. A wavelet correlation analysis between the high temporal-resolution GPS-PWV time series and rainfall events evaluated in this study shows that there are oscillations in the PWV time series correlated with the more intense rainfall events. These oscillations are on scales related to periods from about 32 to 64 min (associated with GPS-PWV jumps) and from 16 to 34 min (associated with positive pulses of the PWV). The GPS-PWV time-derivative histogram for the time window before the rainfall event reveals different distributions influenced by positive pulses of the GPS-PWV (derivative > 9.5 mm/hr) for higher intensity and extension events. These features are indicative of the occurrence of intense precipitation and, consequently, have the potential for application in nowcasting activities. © 2018 Royal Meteorological Society"
"56195639700;7102084129;7409080503;","Estimating the Decoupling Degree of Subtropical Marine Stratocumulus Decks From Satellite",2018,"10.1029/2018GL078382","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055630144&doi=10.1029%2f2018GL078382&partnerID=40&md5=7a5735beae4c9403530c1619dba13e5e","The decoupling degree of stratocumulus (Sc) decks is an important quantity dictating evolutions of Sc. In subtropical oceans, the Sc decoupling is a key intermediate process of the Sc-to-cumulus transitions, a persistent phenomenon that is not fully understood. This study introduces a new approach for estimating the degree of decoupling of subtropical Sc decks using passive satellite sensors. This method is limited to regions where Sc decks are advected over progressively warmer water. This is most common in the subtropics. The estimation concept is that decoupled Sc clouds under cold-advection conditions are fed by spreading of the tops of cumulus clouds that are coupled. The cumulus clouds constitute a much larger liquid water path over small areas, which is identified by a positive skewness of the liquid water path, a quantity measurable from high-resolution satellite data. The decoupling degree here is defined as the difference between the Sc cloud-base height and lifting condensation level that is the cumulus cloud-base height under cold-advection conditions. This concept and the satellite-based estimations are supported by ship measurements over the Northeast Pacific. One-year climatology of the satellite-inferred decoupling degree was generated over the same region, revealing a coherent pattern of offshore decoupling, consistent with previous theory and field-campaign observations. ©2018. The Authors."
"57192700976;57204886915;36868795400;","Objective Quantification of Convective Clustering Observed During the AMIE/DYNAMO Two-Day Rain Episodes",2018,"10.1029/2018JD028497","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054006279&doi=10.1029%2f2018JD028497&partnerID=40&md5=653d2a12a90dee77d837d4554bb797dc","One critical bottleneck in developing and evaluating ways to represent the mesoscale organization of convection in cumulus parameterization schemes is that there is no single accepted method of objectively quantifying the degree of convective organization or clustering from observations. This study addresses this need using high-quality S-PolKa radar data from the Atmospheric Radiation Measurement Madden-Julian Oscillation Investigation Experiment/Dynamics of the Madden-Julian Oscillation (AMIE/DYNAMO) field campaign. We first identify convective elements (contiguous convective echoes [CCEs]) from radar reflectivity observations using the rain type classification algorithm of Powell et al. (2016, https://doi.org/10.1175/JTECH-D-15-0135.1). Then we apply scalar clustering metrics, including the organization index (Iorg) of Tompkins and Semie, to the radar CCEs to test their ability of quantifying convective clustering during the observed two-day rain episodes. Our results show two distinct phases of convective clustering during the two-day rain episodes, with each phase covering about 10 hr before (Phase 1) and after (Phase 2) the time of peak rain rate. In Phase 1 clustering, the number of CCEs increases and convective cells cluster as new cells form preferentially near existing convective entities. The number of CCEs decreases as the environment stabilizes in Phase 2 clustering, during which already clustered cells with associated stratiform clouds are preferred over the isolated ones. Iorg is capable of capturing convective clustering in both phases. The possible mechanisms for convective clustering are discussed, including cold pool-updraft feedback, moisture-convection interaction, and mesoscale circulations. Our results suggest that parameterizations of convective organization should represent the feedback processes that are responsible for the convective clustering during both phases. ©2018. American Geophysical Union. All Rights Reserved."
"56120916000;7407016988;7004369046;7201654851;","Observation of Quasi-2-Day convective disturbances in the equatorial Indian Ocean during DYNAMO",2018,"10.1175/JAS-D-17-0351.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052654546&doi=10.1175%2fJAS-D-17-0351.1&partnerID=40&md5=7839a05ec9c738344031885ec0409cc3","This study examines the westward-propagating convective disturbances with quasi-2-day intervals of occurrence identified over Gan Island in the central Indian Ocean from mid- to late October 2011 during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign. Atmospheric sounding, satellite, and radar data are used to develop a composite of seven such disturbances. Composites and spectral analyses reveal that 1) the quasi-2-day convective events comprise westward-propagating diurnal convective disturbances with phase speeds of 10-12 m s-1whose amplitudes are modulated on a quasi-2-day time scale on a zonal scale of ~1000 km near the longitudes of Gan; 2) the cloud life cycle of quasi-2-day convective disturbances shows a distinct pattern of tropical cloud population evolution-from shallow to deep to stratiform convection; 3) the time scales of mesoscale convective system development and boundary layer modulation play essential roles in determining the periodicity of the quasi-2-day convective events; and 4) in some of the quasi-2-day events there is evidence of counterpropagating (westward and eastward) cloud systems along the lines proposed by Yamada et al. Based on these findings, an interpretation is proposed for the mechanisms for the quasi-2-day disturbances observed during DYNAMO that combines concepts from prior studies of this phenomenon over the western Pacific and Indian Oceans. © 2018 American Meteorological Society."
"55807154400;55735652600;6603360050;36868795400;7006432091;","Kelvin-Helmholtz waves in precipitating midlatitude cyclones",2018,"10.1175/JAS-D-17-0365.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050958325&doi=10.1175%2fJAS-D-17-0365.1&partnerID=40&md5=83abf627a33a3bca952ab1edc7637ffa","This study examines Kelvin-Helmholtz (KH) waves observed by dual-polarization radar in several precipitating midlatitude cyclones during the Olympic Mountains Experiment (OLYMPEX) field campaign along the windward side of the Olympic Mountains in Washington State and in a strong stationary frontal zone in Iowa during the Iowa Flood Studies (IFloodS) field campaign. While KH waves develop regardless of the presence or absence of mountainous terrain, this study indicates that the large-scale flow can be modified when encountering a mountain range in such a way as to promote development of KH waves on the windward side and to alter their physical structure (i.e., orientation and amplitude). OLYMPEX sampled numerous instances of KH waves in precipitating clouds, and this study examines their effects on microphysical processes above, near, and below the melting layer. The dual-polarization radar data indicate that KH waves above the melting layer promote aggregation. KH waves centered in the melting layer produce the most notable signatures in dual-polarization variables, with the patterns suggesting that the KH waves promote both riming and aggregation. Both above and near the melting layer ice particles show no preferred orientation likely because of tumbling in turbulent air motions. KH waves below the melting layer facilitate the generation of large drops via coalescence and/or vapor deposition, increasing mean drop size and rain rate by only slight amounts in the OLYMPEX storms. © 2018 American Meteorological Society."
"57195576398;25941200000;35572096100;9239331500;24337947000;56009810800;35317714900;7003557662;6602681732;6602922400;12800966700;7003535385;8397494800;35567153700;6603631763;","Evaluation of a high-resolution numerical weather prediction model's simulated clouds using observations from CloudSat, GOES-13 and in situ aircraft",2018,"10.1002/qj.3318","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054533459&doi=10.1002%2fqj.3318&partnerID=40&md5=a777a4a748952ef2711a1970af7f1d10","This study aimed to assess tropical cloud properties predicted by Environment and Climate Change Canada's Global Environmental Multiscale (GEM) model when run with the Milbrandt–Yau double-moment cloud microphysical scheme and one-way nesting that culminated at a (∼300 km)2 inner domain with 0.25 km horizontal grid spacing. The assessment utilized satellite and in situ data collected during the High Ice Water Content (HIWC) and High Altitude Ice Crystals (HAIC) projects for a mesoscale convective system on 16 May 2015 over French Guiana. Data from CloudSat's cloud-profiling radar and GOES-13's imager were compared to data either simulated directly by GEM or produced by operating on GEM's cloud data with both the CFMIP (Cloud Feedback Model Intercomparison Project) Observation Simulator Package (COSP) instrument simulator and a three-dimensional Monte Carlo solar radiative transfer model. In situ observations were made from research aircraft – Canada's National Research Council Convair-580 and the French SAFIRE Falcon-20 – whose flight paths were aligned with CloudSat's ground-track. Spatial and temporal shifts of clouds simulated by GEM compared well to GOES-13 imagery. There are, however, differences between simulated and observed amounts of high and low cloud. While GEM did well at predicting ranges of ice-water content (IWC) near 11 km altitude (Falcon-20), it produces too much graupel and snow near 7 km (Convair-580). This produced large differences between CloudSat's and COSP-generated radar reflectivities and two-way attenuations. On the other hand, CloudSat's inferred values of IWC agree well with in situ samples at both altitudes. Generally, GEM's visible reflectances exceeded GOES-13's on account of having produced too much low-level liquid cloud. It is expected that GEM's disproportioning of cloud hydrometeors will improve once it includes a better representation of secondary ice production. © 2018 Her Majesty the Queen in Right of Canada. Quarterly Journal of the Royal Meteorological Society © 2018 Royal Meteorological Society"
"7004040960;57202151788;56108769500;","Thunderstorm characteristics during the Ontario Winter Lake-Effect Systems project",2018,"10.1175/JAMC-D-17-0188.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047361136&doi=10.1175%2fJAMC-D-17-0188.1&partnerID=40&md5=f655331bba62b6cbe3f3b52f9fa810a6","The Ontario Winter Lake-Effect Systems (OWLeS) field campaign during the winter season of 2013/14 provided unprecedented data with regard to the structure and behavior of long-lake-axis-parallel (LLAP) lake-effect storms. One of the interesting characteristics of LLAP storm bands is their ability to initiate lightning. The OWLeS datasets provide an opportunity to examine more thoroughly the kinematics and microphysics of lake-effect thunder-snowstorms than ever before. The OWLeS facilities and field personnel observed six lake-effect thunderstorms during December-January 2013/14. Most of them produced very little lightning (fewer than six cloud-to-ground strokes or intracloud pulses recorded by the National Lightning Detection Network). The 7 January 2014 storm had over 50 strokes and pulses, however, which resulted in 20 flashes over a 6-h period (0630-1230 UTC), making it the most electrically active storm during the field campaign. Relative to the 18 December 2013 storm, which only had three flashes, the 7 January 2014 case had a deeper boundary layer and greater instability. Also, 45% of the lightning during the 7 January storm was likely due to flashes initiated by wind turbines or other man-made antennas, along with all of the lightning observed during 18 December. No lightning was documented over Lake Ontario, the primary source of instability for these storms. © 2018 American Meteorological Society."
"57202425542;12800966700;8657166100;23017945100;6701754792;36573180000;56358933300;11440520800;57194527969;","Evaluation of radar reflectivity factor simulations of ice crystal populations from in situ observations for the retrieval of condensed water content in tropical mesoscale convective systems",2017,"10.5194/amt-10-2239-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020513566&doi=10.5194%2famt-10-2239-2017&partnerID=40&md5=dfe33202f5e65eaffcc97d1a34166ead","This study presents the evaluation of a technique to estimate cloud condensed water content (CWC) in tropical convection from airborne cloud radar reflectivity factors at 94ĝ€GHz and in situ measurements of particle size distributions (PSDs) and aspect ratios of ice crystal populations. The approach is to calculate from each 5ĝ€s mean PSD and flight-level reflectivity the variability of all possible solutions of <i>m</i>(<i>D</i>) relationships fulfilling the condition that the simulated radar reflectivity factor (<b>T</b>-matrix method) matches the measured radar reflectivity factor. For the reflectivity simulations, ice crystals were approximated as oblate spheroids, without using a priori assumptions on the mass-size relationship of ice crystals. The CWC calculations demonstrate that individual CWC values are in the range ±32ĝ€% of the retrieved average <span styleCombining double low line""text-decoration: overline;"">CWC</span> value over all CWC solutions for the chosen 5ĝ€s time intervals. In addition, during the airborne field campaign performed out of Darwin in 2014, as part of the international High Altitude Ice Crystals/High Ice Water Content (HAIC/HIWC) projects, CWCs were measured independently with the new IKP-2 (isokinetic evaporator probe) instrument along with simultaneous particle imagery and radar reflectivity. Retrieved <span styleCombining double low line""text-decoration: overline;"">CWC</span>s from the <b>T</b>-matrix radar reflectivity simulations are on average 16ĝ€% higher than the direct CWCIKP measurements. The differences between the CWCIKP and averaged retrieved <span styleCombining double low line""text-decoration: overline;"">CWC</span>s are found to be primarily a function of the total number concentration of ice crystals. Consequently, a correction term is applied (as a function of total number concentration) that significantly improves the retrieved CWC. After correction, the retrieved <span styleCombining double low line""text-decoration: overline;"">CWC</span>s have a median relative error with respect to measured values of only ĝ'1ĝ€%. Uncertainties in the measurements of total concentration of hydrometeors are investigated in order to calculate their contribution to the relative error of calculated <span styleCombining double low line""text-decoration: overline;"">CWC</span> with respect to measured CWCIKP. It is shown that an overestimation of the concentration by about +50ĝ€% increases the relative errors of retrieved <span styleCombining double low line""text-decoration: overline;"">CWC</span>s by only +29ĝ€%, while possible shattering, which impacts only the concentration of small hydrometeors, increases the relative error by about +4ĝ€%. Moreover, all cloud events with encountered graupel particles were studied and compared to events without observed graupel particles. Overall, graupel particles seem to have the largest impact on high crystal number-concentration conditions and show relative errors in retrieved <span styleCombining double low line""text-decoration: overline;"">CWC</span>s that are higher than for events without graupel particles. © Author(s) 2017. This work is distributed under."
"57192868580;7202230087;35742842700;","Themarine atmospheric boundary layer under strong wind conditions: Organized turbulence structure and flux estimates by airborne measurements",2017,"10.1002/2016JD025960","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013367892&doi=10.1002%2f2016JD025960&partnerID=40&md5=309b781098c4756c4ca060188777f14e","During winter, cold air outbreaks take place in the northwestern Mediterranean sea. They are characterized by local strong winds (Mistral and Tramontane) which transport cold and dry continental air across a warmer sea. In such conditions, high values of surface sensible and latent heat flux are observed, which favor deep oceanic convection. The HyMeX/ASICS-MED field campaign was devoted to the study of these processes. Airborne measurements, gathered in the Gulf of Lion during the winter of 2013, allowed for the exploration of the mean and turbulent structure of the marine atmospheric boundary layer (MABL). A spectral analysis based on an analytical model was conducted on 181 straight and level runs. Profiles of characteristic length scales and sharpness parameter of the vertical wind spectrum revealed larger eddies along the mean wind direction associated with an organization of the turbulence field into longitudinal rolls. These were highlighted by boundary layer cloud bands on high-resolution satellite images. A one-dimensional description of the vertical exchanges is then a tricky issue. Since the knowledge of the flux profile throughout the entire MABL is essential for the estimation of air-sea exchanges, a correction of eddy covariance turbulent fluxes was developed taking into account the systematic and random errors due to sampling and data processing. This allowed the improvement of surface fluxes estimates, computed from the extrapolation of the stacked levels. A comparison between those surface fluxes and bulk fluxes computed at a moored buoy revealed considerable differences, mainly regarding the latent heat flux under strong wind conditions. © 2017. American Geophysical Union. All Rights Reserved."
"6507728803;57190261052;","First in situ observations of binary raindrop collisions",2017,"10.1002/2017GL072516","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010934391&doi=10.1002%2f2017GL072516&partnerID=40&md5=033f023b6a455b19e40ad2afc4f01581","In this article, we present the first-time observations of binary raindrop collisions in rainfall events. These observations constitute a critical step in concluding a long-standing debate on the controlling physical process, binary raindrop collision versus spontaneous raindrop breakup, for the raindrop size distribution (DSD) evolution from cloud to ground level. Our raindrop collision observations were made possible by a new instrument called the High-speed Optical Disdrometer (HOD) that we recently developed for precipitation microphysics investigations. Our approximately 1 year long field campaign that covered 33 rainfall events provided 11 observations of binary raindrop collisions and outcomes but no spontaneous breakup observation. The field-observed collision rate (i.e., number of raindrop collisions within the measurement volume of the HOD per unit time) showed an increasing trend with increasing rain rate as expected from the theoretical collision rate predictions. Furthermore, the field-observed collision rates were (i) comparable (for rain rates less than approximately 50 mm/h) and (ii) significantly larger (for larger rain rates) than the theoretically predicted rates that have been used in various numerical investigations that suggest the controlling role of raindrop collisions in DSD evolution. Our observations, yet to be supplemented with observations from comprehensive field campaigns at different geographic locations and rainfall events for a definitive conclusion, support the collision-driven DSD evolution hypothesis. ©2017. American Geophysical Union. All Rights Reserved."
"56061814400;7801595201;55481777500;13406672500;7005706662;12801992200;","Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime",2016,"10.5194/acp-16-5203-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966701507&doi=10.5194%2facp-16-5203-2016&partnerID=40&md5=3aca8ad91fbddcd5e1509bcfb4975681","There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric vertical structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season. In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements were made of atmospheric precipitable water vapor (PWV) and the liquid water path (LWP) of trade cumulus clouds, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol from instrumentation at a ground observatory and on small unmanned aircraft. We present observations which indicate a positive correlation between aerosol and cloud LWP only when considering cases with low atmospheric water vapor (PWV &lt; 40 kg m-2), a criterion which acts to filter the data to control for the natural meteorological variability in the region. We then use the aircraft and ground-based measurements to explore possible mechanisms behind this observed aerosol-LWP correlation. The increase in cloud liquid water is found to coincide with a lowering of the cloud base, which is itself attributable to increased boundary layer humidity in polluted conditions. High pollution is found to correlate with both higher temperatures and higher humidity measured throughout the boundary layer. A large-scale analysis, using satellite observations and meteorological reanalysis, corroborates these covariations: high-pollution cases are shown to originate as a highly polluted boundary layer air mass approaching the observatory from a northwesterly direction. The source air mass exhibits both higher temperatures and higher humidity in the polluted cases. While the warmer temperatures may be attributable to aerosol absorption of solar radiation over the subcontinent, the factors responsible for the coincident high humidity are less evident: the high-aerosol conditions are observed to disperse with air mass evolution, along with a weakening of the high-temperature anomaly, while the high-humidity condition is observed to strengthen in magnitude as the polluted air mass moves over the ocean toward the site of the CARDEX observations. Potential causal mechanisms of the observed correlations, including meteorological or aerosol-induced factors, are explored, though future research will be needed for a more complete and quantitative understanding of the aerosol-humidity relationship. © Author(s) 2016."
"7202057166;56442378900;7005729142;7403931916;7101653556;6506385754;","The microphysical properties of small ice particles measured by the Small Ice Detector-3 probe during the MACPEX field campaign",2016,"10.1175/JAS-D-16-0126.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003583798&doi=10.1175%2fJAS-D-16-0126.1&partnerID=40&md5=bb07c7f5bb383cf9580169174c20773f","A reliable understanding of the microphysical properties of ice particles in atmospheric clouds is critical for assessing cloud radiative forcing effects in climate studies. Ice particle microphysical properties such as size, shape, and surface roughness all have substantial effects on the single-scattering characteristics of the particles. A recently developed ice particle probe, the Small Ice Detector-3 (SID-3), measures the two-dimensional near-forward light-scattering patterns of sampled ice particles. These scattering patterns provide a wealth of information for understanding the microphysical and radiative characteristics of ice particles. The SID-3 was operated successfully on 12 aircraft flights during the NASA Midlatitude Airborne Cirrus Properties Experiment (MACPEX) field campaign in April 2011. In this study, SID-3 measurements are used to investigate the frequency of occurrence of a number of ice particle properties observed during MACPEX. Individual scattering patterns (7.5°-23°) are used to infer properties of the observed particles as well as to calculate partial scattering functions (PSFs) for ensembles of particles in the measured size range (~5-100 μm). PSFs are compared to ray-tracing-based phase functions to infer additional properties of the particles. Two quantitative values-halo ratio and steepness ratio-are used to characterize PSFs. The MACPEX dataset suggests that most atmospheric ice particles have rough surfaces or are complex in nature. PSFs calculated for particles that were characterized as having smooth surfaces also appeared to more closely resemble rough crystal PSFs. PSFs measured with SID-3 compare well with those calculated for droxtals with rough surfaces. © 2016 American Meteorological Society."
"57207137435;36671579400;7102866124;","Stroke multiplicity and horizontal scale of negative charge regions in thunderclouds",2016,"10.1002/2016GL068924","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978915469&doi=10.1002%2f2016GL068924&partnerID=40&md5=723a76e6276ec1e7919201d04cbf6ac2","An X-band polarimetric radar and multiple lightning detection systems are used to document the initial cloud-to-ground lightning flash in a large number (46 cases) of incipient thunderstorms, as part of the CHUVA-Vale field campaign during the 2011/2012 spring-summer in southeast Brazil. The results show an exceptionally low stroke multiplicity (87% of flashes with single stroke) in the initial ground flashes, a finding consistent with the limited space available for the positive leader extension into new regions of negative space charge in compact cells. The results here are contrasted with the behavior of ground flashes in mesoscale thunderstorms in previous studies. Additionally, we found evidence for a minimum scale (radar echo >20 dBZ) for lightning initiation (>3 km in radius) and that the peak currents of initial cloud-to-ground flashes in these compact thunderstorms are only half as large as return stroke peak currents in general. ©2016. American Geophysical Union. All Rights Reserved."
"57126548600;35113492400;16445036300;55738957800;56611366900;","An observational study of entrainment rate in deep convection",2015,"10.3390/atmos6091362","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032475538&doi=10.3390%2fatmos6091362&partnerID=40&md5=1d8206bde13fe855d8c1e7531a018b52","This study estimates entrainment rate and investigates its relationships with cloud properties in 156 deep convective clouds based on in-situ aircraft observations during the TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment) field campaign over the western Pacific. To the authors' knowledge, this is the first study on the probability density function of entrainment rate, the relationships between entrainment rate and cloud microphysics, and the effects of dry air sources on the calculated entrainment rate in deep convection from an observational perspective. Results show that the probability density function of entrainment rate can be well fitted by lognormal, gamma or Weibull distribution, with coefficients of determination being 0.82, 0.85 and 0.80, respectively. Entrainment tends to reduce temperature, water vapor content and moist static energy in cloud due to evaporative cooling and dilution. Inspection of the relationships between entrainment rate and microphysical properties reveals a negative correlation between volume-mean radius and entrainment rate, suggesting the potential dominance of homogeneous mechanism in the clouds examined. In addition, entrainment rate and environmental water vapor content show similar tendencies of variation with the distance of the assumed environmental air to the cloud edges. Their variation tendencies are non-monotonic due to the relatively short distance between adjacent clouds. © 2015 by the authors."
"6506537159;8658386900;56548748900;36342243200;37018824600;6603431534;","Insights from modeling and observational evaluation of a precipitating continental cumulus event observed during the MC3E field campaign",2015,"10.1002/2014JD022255","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84925589067&doi=10.1002%2f2014JD022255&partnerID=40&md5=f05964e545206dad2257b1c7be9e7053","A case of shallow cumulus and precipitating cumulus congestus sampled at the Atmospheric Radiation Measurement Program Southern Great Plains supersite during the Midlatitude Continental Convective Clouds Experiment is analyzed using a multisensor observational approach and numerical simulation. Observations froma new radar suite surrounding the facility are used to characterize the evolving statistical behavior of the precipitating cloud system. This is accomplished using distributions of different measures of cloud geometry and precipitation properties. Large-eddy simulation (LES) with size-resolved (bin)microphysics is employed to determine the forcings most important in producing the salient aspects of the cloud system captured in the radar observations. Our emphasis is on assessing the importance of time-varying versus steady state large-scale forcing on the model’s ability to reproduce the evolutionary behavior of the cloud system. Additional consideration is given to how the characteristic spatial scale and homogeneity of the forcing imposed on the simulation influences the evolution of cloud system properties. Results indicate that several new scanning radar estimates such as distributions of cloud top are useful to differentiate the value of time-varying (or at least temporally well-matched) forcing on LES solution fidelity. © 2015. American Geophysical Union. All Rights Reserved."
"55831437900;13403622000;57203348817;","Modeling aerosol activation in a tropical, orographic, island setting: Sensitivity tests and comparison with observations",2013,"10.1016/j.atmosres.2013.07.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882754359&doi=10.1016%2fj.atmosres.2013.07.017&partnerID=40&md5=2621971b60d15f807d5e698ac2bd5d07","The aerosol, updraft and cloud droplet observations from the 2011 Dominica Experiment (DOMEX) field campaign provide an interesting opportunity to investigate the process of cloud droplet activation in a tropical, orographic, convective setting. This study involves adiabatic parcel model simulations with a state-of-the-art parameterization of droplet activation, which we run with aerosol size distributions and updraft velocities based on DOMEX data. We compare the cloud droplet concentrations predicted by the parameterization with the observations from DOMEX, and run various sensitivity tests to changes in model inputs on the order of their uncertainty, in order to gain insights into what factors are most important in determining the aerosol activation fraction in this setting. Our control simulations overestimated the observed droplet concentrations, especially for the days with strong trade winds, but in most cases these discrepancies could be eliminated by realistic changes in our assumptions. The remaining error could be the result of entrainment of sub-saturated air, precipitation, or advection of pre-existing clouds from upwind. We found strong sensitivities to the mean updraft velocity and to the size distribution and composition of particles in the Aitken mode, the smallest mode including particles below 100. nm. The Aitken mode accounted for 42% to 68% of the simulated droplet concentration in our control simulations, and simulations excluding the Aitken mode underestimated the observed droplet concentrations under realistic assumptions. Droplets from the Aitken mode dominated the changes in the simulated droplet concentrations in our sensitivity tests. The precision of our simulations, and our ability to constrain the role of the Aitken mode, were limited by our lack of knowledge of the composition and size distribution of Aitken mode particles, highlighting the importance of measuring these variables in field campaigns in similar settings. © 2013 Elsevier B.V."
"8881618800;6701727687;6603405538;24481356300;8940002200;57194628631;6701641583;6602751071;","Measurement of the Arctic UTLS composition in presence of clouds using millimetre-wave heterodyne spectroscopy",2013,"10.5194/amt-6-2683-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885748212&doi=10.5194%2famt-6-2683-2013&partnerID=40&md5=69ee932e062cadbc3c0d03ea37e47336","MARSCHALS (Millimetre-wave Airborne Receivers for Spectroscopic CHaracterisation in Atmospheric Limb Sounding) is a limb viewing instrument working in the millimetre and sub-millimetre spectral regions (from 294 to 349 GHz). The scientific rationale of MARSCHALS is the study of the Upper Troposphere and Lower Stratosphere region. In March 2010 MARSCHALS was deployed on-board the M-55 Geophysica stratospheric aircraft during the PREMIER( PRocess Exploration through Measurements of Infrared and millimetre-wave Emitted Radiation)-Ex field campaign. From the campaign base at Kiruna, Sweden, a research flight to investigate the Arctic atmosphere was conducted. For the first time the instrument fully exploited the three spectral bands. In this paper, we present results of the analysis of MARSCHALS measurements acquired during the PREMIER-Ex flight as processed by the Millimetre-wave Atmospheric Retrieval Code. For the second time after the SCOUT-O3 flight in 2005, MARSCHALS measured vertical distributions of temperature, water vapour, ozone and nitric acid over an altitude range of 4 to 24 km. In addition, vertical profiles of carbon monoxide and nitrous oxide were obtained for the first time. The measurements were performed in clear sky conditions and in presence of low and high altitude clouds (that were able to obscure measurements in the middle infrared spectroscopic region) and some information about thick clouds were extracted from the data. The capabilities to derive information on upper tropospheric and lower stratospheric vertical profiles of temperature and minor constituents from millimetre-wave limb sounding observations in the northern polar region are presented and discussed for each of the individual targets. The results of MARSCHALS data analysis contributed to demonstrate the scientific relevance and technical feasibility of millimetre-wave limbsounding of the UTLS proposed for the ESA Earth Explorer 7 candidate Core Mission PREMIER. PREMIER was not selected at the end of the Earth Explorer 7 evaluation process, but it is still being considered for future launch opportunities. © 2013 Author(s)."
"34869672600;6701596624;57193882808;6507002063;","Modeling microphysical effects of entrainment in clouds observed during EUCAARI-IMPACT field campaign",2013,"10.5194/acp-13-8489-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84883340722&doi=10.5194%2facp-13-8489-2013&partnerID=40&md5=34cae2a184e8c57c55736f9fa90de0dd","This paper discusses aircraft observations and large-eddy simulation (LES) modeling of 15 May 2008, North Sea boundary-layer clouds from the EUCAARI-IMPACT field campaign. These clouds are advected from the northeast by the prevailing lower-tropospheric winds and featured stratocumulus-over-cumulus cloud formations. An almost-solid stratocumulus deck in the upper part of the relatively deep, weakly decoupled marine boundary layer overlays a field of small cumuli. The two cloud formations have distinct microphysical characteristics that are in general agreement with numerous past observations of strongly diluted shallow cumuli on one hand and solid marine stratocumulus on the other. <br><br> Based on the available observations, a LES model setup is developed and applied in simulations using a novel LES model. The model features a double-moment warm-rain bulk microphysics scheme combined with a sophisticated subgrid-scale scheme allowing local prediction of the homogeneity of the subgrid-scale turbulent mixing. The homogeneity depends on the characteristic time scales for the droplet evaporation and for the turbulent homogenization. In the model, these scales are derived locally based on the subgrid-scale turbulent kinetic energy, spatial scale of cloudy filaments, mean cloud droplet radius, and humidity of the cloud-free air entrained into a cloud, all predicted by the LES model. The model reproduces contrasting macrophysical and microphysical characteristics of the cumulus and stratocumulus cloud layers. Simulated subgrid-scale turbulent mixing within the cumulus layer and near the stratocumulus top is on average quite inhomogeneous, but varies significantly depending on the local conditions. © 2013 Author(s) ."
"55533428600;44261675000;44261758800;6701873414;7402900768;","Statistical decision analysis for flight decision support: The SPartICus campaign",2013,"10.1002/jgrd.50237","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84881124984&doi=10.1002%2fjgrd.50237&partnerID=40&md5=40a612a8fe5be301363914e3f33fe38a","Field campaigns in atmospheric science typically require making challenging decisions about how best to deploy limited resources, especially aircraft flight hours. Algorithmic decision tools have shown the potential to outperform traditional heuristic approaches to allocating limited flight hours in field campaigns. The present study examines the utility of algorithmic decision tools in an application to the Atmospheric Radiation Measurement (ARM) Small Particles in Cirrus (SPartICus) campaign, which sampled cirrus clouds over the ARM Southern Great Plains (SGP) site between January and June 2010. Probabilistic forecasts of suitable data collection conditions were generated using relative humidity forecasts from the Global Forecast System (GFS) and self-organizing maps. An optimization procedure based on dynamic programming was then used to generate day-ahead fly/no-fly decisions for research flights over the SGP site. The quality of flight decisions thus generated were compared with those made by the SPartICus science team. Results showed that the algorithmic decision tool would have delivered 11% more optimal data while shortening the length of the campaign season by 29 days and reducing the per-day expenditure of investigator time on activities of forecasting and decision-making. Key pointsAlgorithmic decision tools show promise in field campaign resource allocation.The SPartICus campaign measured cirrus clouds using aircraft.An algorithmic tool could have saved resources, yielded more data. ©2013. American Geophysical Union. All Rights Reserved."
"55947921200;13103943200;6701540733;55366655100;","Variations of electric field and electric resistivity of air caused by dust motion",2013,"10.1002/jgra.50478","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889076684&doi=10.1002%2fjgra.50478&partnerID=40&md5=77ab6a7c454ff28ca7d7aa271174163e","We report results of a field campaign conducted in the Nevada desert with a suite of electric field instruments consisting of a field mill (FM) and a short dipole antenna (SDA). Furthermore, we show that a combination of the measurements of these two instruments allows the estimation of the electric resistivity of air, an important quantity that is extremely difficult to measure near the Earth's surface. The electric resistivity of air is found to vary between 1.5·1013 and 6·1013 Ω m and to correlate with changes in electric field. Vertical DC electric fields with amplitudes up to 6 kV m-1 were observed to correspond to clouds of dust blowing through the measurement site. Enhanced DC and AC electric fields are measured during periods when horizontal wind speed exceeds 7 m s -1, or around twice the background value. We suggest that low-frequency emissions, below ~200 Hz, are generated by the motion of electrically charged particles in the vicinity of the SDA electrode and propose a simple model to reproduce the observed spectra. According to this model, the spectral response is controlled by three parameters, (i) the speed of the charged particles, (ii) the charge concentration, and (iii) the minimum distance between the particle and the electrode. In order to explain the electric fields measured with the FM sensors at different heights, we developed a multilayer model that relates the electric field to the charge distribution. For example, a nonlinear variation of the electric field observed by the FM sensors below 50 cm is simulated by a near-surface layer of tens of centimeters that is filled with electrically charged particles that carry a predominantly negative charge in the vicinity of the soil. The charge concentration inside this layer is estimated to vary between 1012 and 5·1013 electrons m-3. Key Points Electric resistivity of the air is found Enhanced electric fields are measured Low frequency emissions are generated by the dust motion ©2013. American Geophysical Union. All Rights Reserved."
"13404664500;57207415190;9535769800;7401945370;7202954964;55471474500;55996244300;15726586900;57203983376;7103201242;","A prototype quasi real-time intra-seasonal forecasting of tropical convection over the warm pool region: A new challenge of global cloud-system-resolving model for a field campaign",2012,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84892043925&partnerID=40&md5=a1686ad1aa15530a64d02c6309a95777","A new prototype of quasi real-time forecast system for tropical weather events withtimescales spanning across diurnal-to-intra-seasonal ranges is developed. Its hallmark isthe use of a global cloud-system resolving model (GCRM) that avoids uncertaintiesarising from cumulus convection schemes inherent to traditional hydrostatic models. Thisallows forecasting of multi-scale convective disturbances such as tropical cyclones andsuper cloud clusters that are particularly associated with Madden-Julian Oscillation(MJO), even more straightforwardly, with unprecedented details, and disseminatedetailed forecast products to in-situ observation networks. The system can operate, forexample, in an observation campaign in the tropical ocean, where observation network is in synchronous with modeling components to investigate the atmospheric andatmosphere-ocean interaction processes controlling tropical disturbances such as MJO.This chapter overviews the prototype system and reports a first pilot forecastexample of tropical cyclone LAILA that happened over the Indian Ocean in the late May2010. The forecast system with the finest mesh of 14 km over the target region projectedthe overall track and evolution of LAILA quite decently prior to its landfall with up toabout five days lead time. LAILA featured north-westward movement after its genesis inassociation with a propagation of the predicted MJO. The MJO traversed the IndianOcean up about 5-7 days before the genesis of LAILA, according to an MJO indexanalysis from observation. A key ingredient of the encouraging forecast is inferred to bethe GCRM's capability of representing a mechanistic link between LAILA and MJO.Additionally, the forecast system captured a northward migration of precipitationembedded in a synoptic-scale low-level westerly intrusion over the Indian Ocean region,which signals the onset of southwesterly monsoon for this particular year.These findings, albeit from only one specific forecast experiment, lend somereliability to the GCRM-based research forecast of MJO-associated convection events toassist on-site observation planning. Moreover, this suggests a potential pathway of futureGCRM-based forecast system development towards extended seamless intra-seasonalforecast of MJO-associated weather events that would threaten the tropical warm-pooland neighborhood regions. © 2012 Nova Science Publishers, Inc. All rights reserved."
"7101675442;7401744334;6508188345;6603609443;7201608197;7402544414;","Development of laser, detector, and receiver systems for an atmospheric CO2 lidar profiling system",2008,"10.1109/AERO.2008.4526386","https://www.scopus.com/inward/record.uri?eid=2-s2.0-49349084470&doi=10.1109%2fAERO.2008.4526386&partnerID=40&md5=0fa4aa849681485f8e757179309e12ec","A ground-based Differential Absorption Lidar (DIAL) is being developed with the capability to measure range-resolved and column amounts of atmospheric CO2. This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA Earth Science Technology Office's Instrument Incubator Program. This three year program involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. At the end of a three-year development this instrument is expected to be capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO 2 are located. It will be a valuable tool in the validation of NASA Orbiting Carbon Observatory (OCO) measurements of column CO2 and suitable for deployment in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-μm laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements. Atmospheric tests of the laser have been conducted by operating it locked to the CO2 absorption line center, with off-set locking in the side-line mode, and in the off-line position. The reference laser is locked to center of absorption line within 390 kHz. This improves the level of stabilization by factor of 10 compared to earlier configuration. The detector has been characterized in the laboratory and by conducting atmospheric tests at The National Center of Atmospheric Research (NCAR), Boulder, Colorado. The receiver uses an F2.2 all aluminum 40 cm diameter telescope and the system is designed to focus light onto a 200 μm size detector. Subsystem level integration and testing has been completed in the second year. System level testing is planned in the third year along with validation in the late spring of 2008 that involves comparisons with ground-based and aircraft in situ CO2 sensors. ©2008 IEEE."
"8612873300;7102866124;7202530955;6602375917;","Rainfall sensitivity analyses for the HSB sounder: An Amazon case study",2007,"10.1080/01431160601013526","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547689599&doi=10.1080%2f01431160601013526&partnerID=40&md5=f585dfc05b4a01af339c1652dd142598","This work examines the sensitivity of the different channels of the HSB (Humidity Sensor for Brazil), on board the AQUA satellite, for the purpose of retrieving surface rainfall over land. The analysis is carried out in two steps: (a) a theoretical study performed using two radiative transfer models, RTTOV and the so-called Eddington method; and (b) the determination of the correlation between coincident measurements of HSB brightness temperatures and radar rainfall estimates during the DRY-TO-WET/AMC/LBA field campaign held in the Amazon region during September and October 2002. Theoretical results indicate the sensitivity of the HSB to water vapour content and cloud liquid water in the precipitation estimation. Theoretical and experimental analyses show that the channels 150 and 183±GHz are more adapted to estimate precipitation than the 183±1 and 183±3 GHz channels. The simulation analyses clearly show a hierarchy in physical effects that determine the brightness temperature of these channels. The rain and ice scattering dominate over the absorption of liquid water, and the liquid water absorption effect dominates over the absorption of water vapour. The results show that the 150 and 183±7 channels are more sensitive to the variation of liquid water and ice than the 183±1 and 183±3 channels. For the precipitation estimation using these channels, it was found that it is best adapted to the low precipitation rate situations, since the brightness temperature is rapidly saturated in the presence of high intense precipitation. A case study to estimate precipitation using the radar data has shown that it is possible to adjust a curve that relates the precipitation rate to the brightness temperature of the 150 GHz channel with a good level of accuracy for low precipitation rates."
"56000281400;7006423931;","Microphysical and radiative development of a cirrus cloud during FIRE: implications for dynamical effects",1994,"10.1016/0169-8095(94)90080-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-43949151243&doi=10.1016%2f0169-8095%2894%2990080-9&partnerID=40&md5=3765b7aed3790220d6e4ea07cbbeee7b","Data for this study were collected over Minnesota on 19 October, 1986 during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) cirrus field campaign. Broadband radiometers mounted on the top and bottom of the NCAR King Air and Saberliner aircraft were used to measure irradiances. Constant altitude flight legs were flown at various altitudes within cirrus clouds. The data were averaged over the 60-km flight legs and used to calculate radiative heating rate profiles and cloud radiative properties over the resolved layers from 6 to 12 km. Adiabatic vertical velocity w (cooling rate) required to balance (compensate) the observed radiative heating rates was calculated. Values ranged from about 0.40 m s-1 at mid-cloud levels (8.2 km) to 0.05 m s-1 at the 10 km level. In the absence of other processes, the pattern of radiative heating would have generated a unstable thermal stratification (∂θ/∂z &lt; 0) at the 8.2 km level where a near neutrally stratified layer was observed within the cloud. Observations of the cirrus could ice particle size distribution and habit were used to define the cloud ice water content profile. Assuming steady state supersaturation (S) with respect to ice, the rate of adiabatic ascent required to maintain constant S against the effects of diffusional growth of the ice particles was calculated. The resulting vertical motions were found to be comparable to, but smaller than, those needed to compensate the effects of radiative heating. © 1994."
"55911904900;7006790175;56936076000;7003776691;57126848900;35263854800;6602900485;7401881004;55188724900;22635999400;7005477332;7003729315;57205143137;57212818622;7004315232;7005891596;21742622200;27868213600;6506718750;7801541312;7004166136;6701416358;56423749400;57219284442;56016057500;24578264300;57208225926;35547214900;57219279623;57194868290;6506532311;9640480500;12646426700;7402942478;8510641000;37094057400;57206456336;56515407100;56767841200;56888217500;55706282100;8627503500;","The Aerosol Characterization from Polarimeter and Lidar (ACEPOL) airborne field campaign",2020,"10.5194/essd-12-2183-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089124034&doi=10.5194%2fessd-12-2183-2020&partnerID=40&md5=9b48a2cf2cb5cfab0c1fb9fccc1504d2","In the fall of 2017, an airborne field campaign was conducted from the NASA Armstrong Flight Research Center in Palmdale, California, to advance the remote sensing of aerosols and clouds with multi-Angle polarimeters (MAP) and lidars. The Aerosol Characterization from Polarimeter and Lidar (ACEPOL) campaign was jointly sponsored by NASA and the Netherlands Institute for Space Research (SRON). Six instruments were deployed on the ER-2 high-Altitude aircraft. Four were MAPs: The Airborne Hyper Angular Rainbow Polarimeter (AirHARP), the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI), the Airborne Spectrometer for Planetary EXploration (SPEX airborne), and the Research Scanning Polarimeter (RSP). The remainder were lidars, including the Cloud Physics Lidar (CPL) and the High Spectral Resolution Lidar 2 (HSRL-2). The southern California base of ACEPOL enabled observation of a wide variety of scene types, including urban, desert, forest, coastal ocean, and agricultural areas, with clear, cloudy, polluted, and pristine atmospheric conditions. Flights were performed in coordination with satellite overpasses and ground-based observations, including the Groundbased Multiangle SpectroPolarimetric Imager (GroundMSPI), sun photometers, and a surface reflectance spectrometer. ACEPOL is a resource for remote sensing communities as they prepare for the next generation of spaceborne MAP and lidar missions. Data are appropriate for algorithm development and testing, instrument intercomparison, and investigations of active and passive instrument data fusion. They are freely available to the public. The DOI for the primary database is https://doi.org/10.5067/SUBORBITAL/ACEPOL2017/DATA001 (ACEPOL Science Team, 2017), while for AirMSPI it is https://doi.org/10.5067/AIRCRAFT/AIRMSPI/ACEPOL/RADIANCE/ELLIPSOID-V006 and https://doi.org/10.5067/AIRCRAFT/AIRMSPI/ACEPOL/RADIANCE/TERRAIN-V006 (ACEPOL AirMSPI 75 Science Team, 2017a, b). GroundMSPI data are at https://doi.org/10.5067/GROUND/GROUNDMSPI/ACEPOL/RADIANCE-v009 (GroundMSPI Science Team, 2017). Table 3 lists further details of these archives. This paper describes ACEPOL for potential data users and also provides an outline of requirements for future field missions with similar objectives. © 2020 BMJ Publishing Group. All rights reserved."
"57202194815;57212509672;56447276100;57214202915;7403253796;56733854600;57202204544;57193091858;57095410800;57211149101;57212504204;8075033200;7409080503;","Contrasting size-resolved hygroscopicity of fine particles derived by HTDMA and HR-ToF-AMS measurements between summer and winter in Beijing: The impacts of aerosol aging and local emissions",2020,"10.5194/acp-20-915-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078772144&doi=10.5194%2facp-20-915-2020&partnerID=40&md5=7fdce48c8ed5dab23d51be4a24c2fdb1","<p>The effects of aerosols on visibility through scattering and absorption of light and on climate through altering cloud droplet concentration are closely associated with their hygroscopic properties. Here, based on field campaigns in winter and summer in Beijing, we compare the size-resolved hygroscopic parameter (<span classCombining double low line""inline-formula""><i>κ</i>gf</span>) of ambient fine particles derived by an HTDMA (hygroscopic tandem differential mobility analyzer) to that (denoted as <span classCombining double low line""inline-formula""><i>κ</i>chem</span>) calculated by an HR-ToF-AMS (high-resolution time-of-flight aerosol mass spectrometer) measurements using a simple rule with the hypothesis of uniform internal mixing of aerosol particles. We mainly focus on contrasting the disparity of <span classCombining double low line""inline-formula""><i>κ</i>gf</span> and <span classCombining double low line""inline-formula""><i>κ</i>chem</span> between summer and winter to reveal the impact of atmospheric processes/emission sources on aerosol hygroscopicity and to evaluate the uncertainty in estimating particle hygroscopicity with the hypothesis. We show that, in summer, the <span classCombining double low line""inline-formula""><i>κ</i>chem</span> for 110, 150, and 200&thinsp;nm particles was on average <span classCombining double low line""inline-formula"">ĝ1/410</span>&thinsp;%-12&thinsp;% lower than <span classCombining double low line""inline-formula""><i>κ</i>gf</span>, with the greatest difference between the values observed around noontime when aerosols experience rapid photochemical aging. In winter, no apparent disparity between <span classCombining double low line""inline-formula""><i>κ</i>chem</span> and <span classCombining double low line""inline-formula""><i>κ</i>gf</span> is observed for those <span classCombining double low line""inline-formula"">&gt;100</span>&thinsp;nm particles around noontime, but the <span classCombining double low line""inline-formula""><i>κ</i>chem</span> is much higher than <span classCombining double low line""inline-formula""><i>κ</i>gf</span> in the late afternoon when ambient aerosols are greatly influenced by local traffic and cooking sources. By comparing with the observation from the other two sites (Xingtai, Hebei and Xinzhou, Shanxi) of north China, we verify that atmospheric photochemical aging of aerosols enhances their hygroscopicity and leads to 10&thinsp;%-20&thinsp;% underestimation in <span classCombining double low line""inline-formula""><i>κ</i>chem</span> if using the uniform internal mixing assumption. The effect is found more significant for these <span classCombining double low line""inline-formula"">&gt;100</span>&thinsp;nm particles observed in remote or clean regions. The lower <span classCombining double low line""inline-formula""><i>κ</i>chem</span> likely resulted from multiple impacts of inappropriate application of the density and hygroscopic parameter of organic aerosols in the calculation, as well as influences from chemical interaction between organic and inorganic compounds on the overall hygroscopicity of mixed particles. We also find that local/regional primary emissions, which result in a large number of externally mixed BC (black carbon) and POA (primary organic aerosol) in urban Beijing during traffic rush hour time, cause a 20&thinsp;%-40&thinsp;% overestimation of the hygroscopic parameter. This is largely due to an inappropriate use of density of the BC particles that is closely associated with its morphology or the degree of its aging. The results show that the calculation can be improved by applying an effective density of fresh BC (0.25-0.45&thinsp;g&thinsp;cm<span classCombining double low line""inline-formula"">-3</span>) in the mixing<span idCombining double low line""page916""/> rule assumption. Our study suggests that it is critical to measure the effective density and morphology of ambient BC, in particular in those regions with influences of rapid secondary conversion/aging processes and local sources, so as to accurately parameterize the effect of BC aging on particle hygroscopicity.</p>. © 2020 Copernicus GmbH. All rights reserved."
"7102643810;8277424000;57218487064;7102190308;6701653010;","The GPM ground validation program",2020,"10.1007/978-3-030-35798-6_2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084673846&doi=10.1007%2f978-3-030-35798-6_2&partnerID=40&md5=d831030e3095d04d94a1d4592f4a84fa","We present a detailed overview of the structure and activities associated with the NASA-led ground-validation component of the NASA-JAXA Global Precipitation Measurement (GPM) mission. The overarching philosophy and approaches for NASA’s GV program are presented with primary focus placed on aspects of direct validation and a summary of physical validation campaigns and results. We describe a spectrum of key instruments, methods, field campaigns and data products developed and used by NASA’s GV team to verify GPM level-2 precipitation products in rain and snow. We describe the tools and analysis framework used to confirm that NASA’s Level-1 science requirements for GPM are met by the GPM Core Observatory. Examples of routine validation activities related to verification of Integrated Multi-satellitE Retrievals for GPM (IMERG) products for two different regions of the globe (Korea and the US) are provided, and a brief analysis related to IMERG performance in the extreme rainfall event associated with Hurricane Florence is discussed. © Springer Nature Switzerland AG 2020."
"57212168597;55717074000;55675283100;57193451125;56119479900;57191226379;54783792600;7410041005;7401936984;","Impacts of Representing Heterogeneous Distribution of Cloud Liquid and Ice on Phase Partitioning of Arctic Mixed-Phase Clouds with NCAR CAM5",2019,"10.1029/2019JD030502","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076093879&doi=10.1029%2f2019JD030502&partnerID=40&md5=dfdee6a990ffeabbc56de0bda50efc95","In this study, we conduct sensitivity experiments with the Community Atmosphere Model version 5 to understand the impact of representing heterogeneous distribution between cloud liquid and ice on the phase partitioning in mixed-phase clouds through different perturbations on the Wegener-Bergeron-Findeisen (WBF) process. In two experiments, perturbation factors that are based on assumptions of pocket structure and the partial homogeneous cloud volume derived from the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observation (HIPPO) campaign are utilized. Alternately, a mass-weighted assumption is used in the calculation of WBF process to mimic the appearance of unsaturated area in mixed-phase clouds as the result of heterogeneous distribution. Model experiments are tested in both single column and weather forecast modes and evaluated against data from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program's Mixed-Phase Arctic Cloud Experiment (M-PACE) field campaign and long-term ground-based multisensor measurements. Model results indicate that perturbations on the WBF process can significantly modify simulated microphysical properties of Arctic mixed-phase clouds. The improvement of simulated cloud water phase partitioning tends to be linearly proportional to the perturbation magnitude that is applied in the three different sensitivity experiments. Cloud macrophysical properties such as cloud fraction and frequency of occurrence of low-level mixed-phase clouds are less sensitive to the perturbation magnitude than cloud microphysical properties. Moreover, this study indicates that heterogeneous distribution between cloud hydrometeors should be treated consistently for all cloud microphysical processes. The model vertical resolution is also important for liquid water maintenance in mixed-phase clouds. ©2019. American Geophysical Union. All Rights Reserved."
"55879760100;54982705800;35551238800;55554574300;15319055900;","The role of aerosol-radiation-cloud interactions in linking anthropogenic pollution over southern west Africa and dust emission over the Sahara",2019,"10.5194/acp-19-14657-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076085036&doi=10.5194%2facp-19-14657-2019&partnerID=40&md5=8fe32203671c08a7e6419caa45887775","The aerosol direct and indirect effects are studied over west Africa in the summer of 2016 using the coupled WRF-CHIMERE regional model including aerosol-cloud interaction parameterization. First, a reference simulation is performed and compared with observations acquired during the Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) field campaign which took place in June and July 2016. Sensitivity experiments are also designed to gain insights into the impact of the aerosols dominating the atmospheric composition in southern west Africa (one simulation with halved anthropogenic emissions and one with halved mineral dust emissions). The most important effect of aerosol-cloud interactions is found for the mineral dust scenario, and it is shown that halving the emissions of mineral dust decreases the 2 m temperature by 0.5 K and the boundary layer height by 25 m on a monthly average (July 2016) and over the Saharan region. The presence of dust aerosols also increases (decreases) the shortwave (longwave) radiation at the surface by 25 W m-2. It is also shown that the decrease of anthropogenic emissions along the coast has an impact on the mineral dust load over west Africa by increasing their emissions in the Saharan region. It is due to a mechanism where particulate matter concentrations are decreased along the coast, imposing a latitudinal shift of the monsoonal precipitation and, in turn, an increase of the surface wind speed over arid areas, inducing more mineral dust emissions. © 2019 Author(s)."
"55324559500;7003510880;26422803600;56149598900;56032594900;55747201700;6603423022;","What controls the formation of nocturnal low-level stratus clouds over southern West Africa during the monsoon season?",2019,"10.5194/acp-19-13489-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069232427&doi=10.5194%2facp-19-13489-2019&partnerID=40&md5=e14d3ea62525baa1324f089e4e0f9fe1","Nocturnal low-level stratus clouds (LLCs) are frequently observed in the atmospheric boundary layer (ABL) over southern West Africa (SWA) during the summer monsoon season. Considering the effect these clouds have on the surface energy and radiation budgets as well as on the diurnal cycle of the ABL, they are undoubtedly important for the regional climate. However, an adequate representation of LLCs in the state-of-the-art weather and climate models is still a challenge, which is largely due to the lack of high-quality observations in this region and gaps in understanding of underlying processes. In several recent studies, a unique and comprehensive data set collected in summer 2016 during the DACCIWA (Dynamics-aerosol-chemistry-cloud interactions in West Africa) ground-based field campaign was used for the first observational analyses of the parameters and physical processes relevant for the LLC formation over SWA. However, occasionally stratus-free nights occur during the monsoon season as well. Using observations and ERA5 reanalysis, we investigate differences in the boundary-layer conditions during 6 stratus-free and 20 stratus nights observed during the DACCIWA campaign. Our results suggest that the interplay between three major mechanisms is crucial for the formation of LLCs during the monsoon season: (i) the onset time and strength of the nocturnal low-level jet (NLLJ), (ii) horizontal cold-air advection, and (iii) background moisture level. Namely, weaker or later onset of NLLJ leads to a reduced contribution from horizontal cold-air advection. This in turn results in weaker cooling, and thus saturation is not reached. Such deviation in the dynamics of the NLLJ is related to the arrival of a cold air mass propagating northwards from the coast, called Gulf of Guinea maritime inflow. Additionally, stratus-free nights occur when the intrusions of dry air masses, originating from, for example, central or South Africa, reduce the background moisture over large parts of SWA. Backward-trajectory analysis suggests that another possible reason for clear nights is descending air, which originated from drier levels above the marine boundary layer. © 2019 BMJ Publishing Group. All rights reserved."
"57213471756;57198129543;57211316425;13608035400;57211324537;","The potential for discriminating microphysical processes in numerical weather forecasts using airborne polarimetric radio occultations",2019,"10.3390/rs11192268","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073479097&doi=10.3390%2frs11192268&partnerID=40&md5=9dc56bdcb7a47da57dd382328f2df17d","Accurate representation of cloud microphysical processes in numerical weather and climate models has proven challenging, in part because of the highly specialized instrumentation required for diagnosing errors in simulated distributions of hydrometeors. Global Navigation Satellite System (GNSS) polarimetric radio occultation (PRO) is a promising new technique that is sensitive to hydrometeors and has the potential to help address these challenges by providing microphysical observations that are relevant to larger spatial scales, especially if this type of observing system can be implemented on aircraft that can target heavy precipitation events. Two numerical experiments were run using a mesoscale model configured with two different microphysical parameterization schemes for a very intense atmospheric river (AR) event that was sampled by aircraft deploying dropsondes just before it made landfall in California, during the CalWater 2015 field campaign. The numerical experiments were used to simulate profiles of airborne polarimetric differential phase delay observations. The differential phase delay due to liquid water hydrometeors below the freezing level differed significantly in the two experiments, as well as the height of the maximum differential phase delay due to all hydrometeors combined. These results suggest that PRO observations from aircraft have the potential to contribute to validating and improving the representation of microphysical processes in numerical weather forecasts once these observations become available. © 2019 by the authors."
"36177823900;56485968500;6602176524;24587715900;7402838215;55469200300;","Convective hydration in the tropical tropopause layer during the StratoClim aircraft campaign: Pathway of an observed hydration patch",2019,"10.5194/acp-19-11803-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072613832&doi=10.5194%2facp-19-11803-2019&partnerID=40&md5=3bca3318d42df205723af05571aa3488","The source and pathway of the hydration patch in the TTL (tropical tropopause layer) that was measured during the Stratospheric and upper tropospheric processes for better climate predictions (StratoClim) field campaign during the Asian summer monsoon in 2017 and its connection to convective overshoots are investigated. During flight no. 7, two remarkable layers are measured in the TTL, namely (1) the moist layer (ML) with a water vapour content of 4.8-5.7ppmv in altitudes of 18-19km in the lower stratosphere and (2) the ice layer (IL) with ice content up to 1.9eq.ppmv (equivalent parts per million by volume) in altitudes of 17-18km in the upper troposphere at around 06:30UTC on 8 August to the south of Kathmandu (Nepal). A Meso-NH convection-permitting simulation succeeds in reproducing the characteristics of the ML and IL. Through analysis, we show that the ML and IL are generated by convective overshoots that occurred over the Sichuan Basin about 1.5d before. Overshooting clouds develop at altitudes up to 19km, hydrating the lower stratosphere of up to 20km with 6401t of water vapour by a strong-to-moderate mixing of the updraughts with the stratospheric air. A few hours after the initial overshooting phase, a hydration patch is generated, and a large amount of water vapour (above 18ppmv) remains at even higher altitudes up to 20.5km while the anvil cloud top descends to 18.5km. At the same time, a great part of the hydrometeors falls shortly, and the water vapour concentration in the ML and IL decreases due to turbulent diffusion by mixing with the tropospheric air, ice nucleation, and water vapour deposition. As the hydration patch continues to travel toward the south of Kathmandu, tropospheric tracer concentration increases up to 30% and 70% in the ML and IL, respectively. The air mass in the layers becomes gradually diffused, and it has less and less water vapour and ice content by mixing with the dry tropospheric air. © Author(s) 2019."
"56241364500;57200278309;57201651168;6603180620;6701679993;16217869500;6603286383;57195682350;56392725800;7005196695;55914433400;","Anthropogenic VOCs in Abidjan, southern West Africa: From source quantification to atmospheric impacts",2019,"10.5194/acp-19-11721-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072610196&doi=10.5194%2facp-19-11721-2019&partnerID=40&md5=07306ed90d9ab58adeb0cd70f0de5284","Several field campaigns were conducted in the framework of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project to measure a broad range of atmospheric constituents. Here we present the analysis of an unprecedented and comprehensive dataset integrating up to 56 volatile organic compounds (VOCs) from ambient sites and emission sources. VOCs were collected on multi-sorbent tubes in the coastal city of Abidjan, Côte d'Ivoire, in winter and summer 2016 and later analysed by gas chromatography coupled with flame ionization and mass spectrometer detectors (GC-FID and GC-MS) at the laboratory. The comparison between VOC emission source profiles and ambient profiles suggests the substantial impact of two-stroke motorized two-wheel vehicles and domestic fires on the composition of Abidjan's atmosphere. However, despite high VOC concentrations near-source, moderate ambient levels were observed (by factors of 10 to 4000 lower), similar to the concentrations observed in northern mid-latitude urban areas. Besides photochemistry, the reported high wind speeds seem to be an essential factor that regulates air pollution levels in Abidjan. Emission ratios (ΔVOC/CO) were established based on real-world measurements achieved for a selected number of representative combustion sources. Maximum measured molar mass emissions were observed from two-wheel vehicles, surpassing other regional sources by 2 orders of magnitude. Local practices like waste burning also make a significant contribution to VOC emissions, higher than those from light-duty vehicles by 1.5 to 8 orders of magnitude. These sources also largely govern the VOC's atmospheric impacts in terms of OH reactivity, secondary organic aerosol formation (SOAP), and photochemical ozone creation potential (POCP). While the contribution of aromatics dominates the atmospheric impact, our measurements reveal the systematic presence of anthropogenic terpenoids in all residential combustion sectors. Finally, emission factors were used to retrieve and quantify VOC emissions from the main anthropogenic source sectors at the national level. Our detailed estimation of VOC emissions suggests that the road transport sector is the dominant source in Côte d'Ivoire, emitting around 1200Gg yr-1 of gas-phase VOCs. These new estimates are 100 and 160 times larger than global inventory estimations from MACCity or EDGAR (v4.3.2), respectively. Additionally, the residential sector is largely underestimated in the global emission inventories, by factors of 13 to 43. Considering only Côte d'Ivoire, these new estimates for VOCs are 3 to 6 times higher than the whole of Europe. Given the significant underestimation of VOC emissions from the transport and residential sectors in Côte d'Ivoire, there is an urgent need to build more realistic and region-specific emission inventories for the entire West African region. This might be true not only for VOCs, but also for all atmospheric pollutants. The lack of waste burning, wood fuel burning and charcoal burning, and fabrication representation in regional inventories also needs to be addressed, particularly in low-income areas where these types of activities are ubiquitous sources of VOC emissions. © Author(s) 2019."
"36647270000;55915046600;55259753300;22133430700;6603180620;8853393600;35789369900;18438062100;57212964448;7401972139;8084443000;55821210800;57217869945;55800632700;7004393835;6505637161;6602189006;57210701130;7006204597;56212055700;35621058500;14630270800;18635043900;14830593700;57210706412;57213239903;57205443911;6603776134;7005628166;57210699625;26027446700;57132773800;","Preliminary results from the FARCE 2015 campaign: Multidisciplinary study of the forest-gas-aerosol-cloud system on the tropical island of la Réunion",2019,"10.5194/acp-19-10591-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071264372&doi=10.5194%2facp-19-10591-2019&partnerID=40&md5=ebf82bec1483c09da3aaff5d1e257c65","The Forests gAses aeRosols Clouds Exploratory (FARCE) campaign was conducted in March-April 2015 on the tropical island of La Réunion. For the first time, several scientific teams from different disciplines collaborated to provide reference measurements and characterization of La Réunion vegetation, volatile organic compounds (VOCs), biogenic VOCs (BVOCs), (bio)aerosols and composition of clouds, with a strong focus on the Maïdo mountain slope area. The main observations obtained during this 2-month intensive field campaign are summarized. They include characterizations of forest structure, concentrations of VOCs and precursors emitted by forests, aerosol loading and optical properties in the planetary boundary layer (PBL), formation of new particles by nucleation of gas-phase precursors, ice-nucleating particles concentrations, and biological loading in both cloud-free and cloudy conditions. Simulations and measurements confirm that the Maïdo Observatory lies within the PBL from late morning to late evening and that, when in the PBL, the main primary sources impacting the Maïdo Observatory are of marine origin via the Indian Ocean and of biogenic origin through the dense forest cover. They also show that (i) the marine source prevails less and less while reaching the observatory; (ii) when in the PBL, depending on the localization of a horizontal wind shear, the Maïdo Observatory can be affected by air masses coming directly from the ocean and passing over the Maïdo mountain slope, or coming from inland; (iii) bio-aerosols can be observed in both cloud-free and cloudy conditions at the Maïdo Observatory; (iv) BVOC emissions by the forest covering the Maïdo mountain slope can be transported upslope within clouds and are a potential cause of secondary organic aerosol formation in the aqueous phase at the Maïdo Observatory; and (v) the simulation of dynamics parameters, emitted BVOCs and cloud life cycle in the Meso-NH model are realistic, and more advanced Meso-NH simulations should use an increased horizontal resolution (100m) to better take into account the orography and improve the simulation of the wind shear front zone within which lies the Maïdo Observatory. Using various observations and simulations, this work draws up an inventory of the in situ studies that could be performed in La Réunion and at the Maïdo Observatory. It also aims to develop scientific collaborations and to support future scientific projects in order to better understand the forest-gas-aerosol-cloud system in an insular tropical environment. © 2019 Author(s)."
"7202057166;36057442400;24450860900;7005729142;57211295702;57205787051;","The fall speed variability of similarly sized ice particle aggregates",2019,"10.1175/JAMC-D-18-0291.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073387388&doi=10.1175%2fJAMC-D-18-0291.1&partnerID=40&md5=fed60fcaf4cf8ead471cb69d1b8f0023","The terminal velocity (Vt) of ice hydrometeors is of high importance to atmospheric modeling. Vt is governed by the physical characteristics of a hydrometeor, including mass and projected area, as well as environmental conditions. When liquid hydrometeors coalesce to form larger hydrometeors, the resulting hydrometeor can readily be characterized by its spherical or near-spherical shape. For ice hydrometeors, it is more complicated because of the variability of ice shapes possible in the atmosphere as well as the inherent randomness in the aggregation process, which leads to highly variable characteristics. The abundance of atmospheric processes affecting ice particle dimensional characteristics creates potential for highly variable Vt for ice particles that are predicted or measured to be of the ‘‘same size.’’ In this article we explore the variability of ice hydrometeor Vt both theoretically and through the use of experimental observations. Theoretically, the variability in Vt is investigated by analyzing the microphysical characteristics of randomly aggregated hexagonal shapes. The modeled dimensional characteristics are then compared to aircraft probe measurements to constrain the variability in atmospheric ice hydrometeor Vt. Results show that the spread in Vt can be represented with Gaussian distributions relative to a mean. Variability expressed as the full width at half maximum of the normalized Gaussian probability distribution function is around 20%, with somewhat higher values associated with larger particle sizes and warmer temperatures. Field campaigns where mostly convective clouds were sampled displayed low variability, while Arctic and midlatitude winter campaigns showed broader Vt spectra. © 2019 American Meteorological Society. Policy (www.ametsoc.org/PUBSReuseLic."
"55875842200;7409080503;","Aerosol properties and their influences on low warm clouds during the Two-Column Aerosol Project",2019,"10.5194/acp-19-9515-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069636231&doi=10.5194%2facp-19-9515-2019&partnerID=40&md5=da01b8b471327e40e93dcd5596503190","Twelve months of measurements collected during the Two-Column Aerosol Project field campaign at Cape Cod, Massachusetts, which started in the summer of 2012, were used to investigate aerosol physical, optical, and chemical properties and their influences on the dependence of cloud development on thermodynamic (i.e., lower tropospheric stability, LTS) conditions. Relationships between aerosol loading and cloud properties under different dominant air-mass conditions and the magnitude of the first indirect effect (FIE), as well as the sensitivity of the FIE to different aerosol compositions, are examined. The seasonal variation in aerosol number concentration (Na) was not consistent with variations in aerosol optical properties (i.e., scattering coefficient, ss, and columnar aerosol optical depth). Organics were found to have a large contribution to small particle sizes. This contribution decreased during the particle growth period. Under low-aerosol-loading conditions, the liquid water path (LWP) and droplet effective radius (DER) significantly increased with increasing LTS, but, under highaerosol-loading conditions, LWP and DER changed little, indicating that aerosols significantly weakened the dependence of cloud development on LTS. The reduction in LWP and DER from low- to high-aerosol-loading conditions was greater in stable environments, suggesting that clouds under stable conditions are more susceptible to aerosol perturbations than those under more unstable conditions. High aerosol loading weakened the increase in DER as LWP increased and strengthened the increase in cloud optical depth (COD) with increasing LWP, resulting in changes in the interdependence of cloud properties. Under both continental and marine air-mass conditions, high aerosol loading can significantly increase COD and decrease LWP and DER, narrowing their distributions. Magnitudes of the FIE estimated under continental air-mass conditions ranged from 0:07 ± 0:03 to 0:26 ± 0:09 with a mean value of 0:16 ± 0:03 and showed an increasing trend as LWP increased. The calculated FIE values for aerosols with a low fraction of organics are greater than those for aerosols with a high fraction of organics. This implies that clouds over regions dominated by aerosol particles containing mostly inorganics are more susceptible to aerosol perturbations, resulting in larger climate forcing, than clouds over regions dominated by organic aerosol particles. © 2019 Author(s)."
"57188971800;7005054220;7102913661;55314628400;56591838400;7404327420;","Wet Scavenging in WRF-Chem Simulations of Parameterized Convection for a Severe Storm During the DC3 Field Campaign",2019,"10.1029/2019JD030484","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068503988&doi=10.1029%2f2019JD030484&partnerID=40&md5=6a20b8ac9baf8f420ba85f9fc4d70128","Deep convection can transport surface moisture and pollution from the planetary boundary layer to the upper troposphere (UT) within a few minutes. The convective transport of precursors of both ozone and aerosols from the planetary boundary layer affects the concentrations of these constituents in the UT and can influence the Earth's radiation budget and climate. Some precursors of both ozone and aerosols are soluble and reactive in the aqueous phase. This study uses the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate the wet scavenging of precursors of both ozone and aerosols including CH2O, CH3OOH, H2O2, and SO2 in a supercell system observed on 29 May 2012, during the 2012 Deep Convective Clouds and Chemistry (DC3) field campaign at cloud-parameterized resolution. The default WRF-Chem simulations underestimate the mixing ratios of soluble ozone precursors in the UT because the dissolved soluble trace gases are not released when the droplets freeze. In order to improve the model simulation of cloud-parameterized wet scavenging, we added ice retention factors for various species to the cloud-parameterized wet scavenging module and adjusted the conversion rate of cloud water to rainwater at temperatures below freezing in the cloud parameterization as well as in the subgrid-scale wet-scavenging calculation. The introduction of these model modifications greatly improved the model simulation of less soluble species. ©2019. American Geophysical Union. All Rights Reserved."
"36616603800;57039067500;57207468002;55926045100;57209793755;55314647100;10046289000;","Evaluation of ambient ammonia measurements from a research aircraft using a closed-path QC-TILDAS operated with active continuous passivation",2019,"10.5194/amt-12-3717-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068776976&doi=10.5194%2famt-12-3717-2019&partnerID=40&md5=f8321614006933f35fa9446b9e7c6b78","A closed-path quantum-cascade tunable infrared laser direct absorption spectrometer (QC-TILDAS) was outfitted with an inertial inlet for filter-less separation of particles and several custom-designed components including an aircraft inlet, a vibration isolation mounting plate, and a system for optionally adding active continuous passivation for gas-phase measurements of ammonia (NH3) from a research aircraft. The instrument was then deployed on the NSF/NCAR C-130 aircraft during research flights and test flights associated with the Western wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WECAN) field campaign. The instrument was configured to measure large, rapid gradients in gas-phase NH3, over a range of altitudes, in smoke (e.g., ash and particles), in the boundary layer (e.g., during turbulence and turns), in clouds, and in a hot aircraft cabin (e.g., average aircraft cabin temperatures expected to exceed 30 °C during summer deployments). Important design goals were to minimize motion sensitivity, maintain a reasonable detection limit, and minimize NH3 ""stickiness"" on sampling surfaces to maintain fast time response in flight. The observations indicate that adding a high-frequency vibration to the laser objective in the QC-TILDAS and mounting the QC-TILDAS on a customdesigned vibration isolation plate were successful in minimizing motion sensitivity of the instrument during flight. Allan variance analyses indicate that the in-flight precision of the instrument is 60 ppt at 1 Hz corresponding to a 3σ detection limit of 180 ppt. Zero signals span ±200, or 400 pptv total, with cabin pressure and temperature and altitude in flight. The option for active continuous passivation of the sample flow path with 1H,1H-perfluorooctylamine, a strong perfluorinated base, prevented adsorption of both water and basic species to instrument sampling surfaces. Characterization of the time response in flight and on the ground showed that adding passivant to a ""clean"" instrument system had little impact on the time response. In contrast, passivant addition greatly improved the time response when sampling surfaces became contaminated prior to a test flight. The observations further show that passivant addition can be used to maintain a rapid response for in situ NH3 measurements over the duration of an airborne field campaign (e.g., ∼ 2 months) since passivant addition also helps to prevent future buildup of water and basic species on instrument sampling surfaces. Therefore, we recommend the use of active continuous passivation with closed-path NH3 instruments when rapid (&gt; 1 Hz) collection of NH3 is important for the scientific objective of a field campaign (e.g., sampling from aircraft or another mobile research platform). Passivant addition can be useful for maintaining optimum operation and data collection in NH3-rich and humid environments or when contamination of sampling surfaces is likely, yet frequent cleaning is not possible. Passivant addition may not be necessary for fast operation, even in polluted environments, if sampling surfaces can be cleaned when the time response has degraded. © Author(s) 2019."
"55880478000;6507400558;57204253860;56242059600;","Using Radar Data to Calibrate a Stochastic Parametrization of Organized Convection",2019,"10.1029/2018MS001537","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067459521&doi=10.1029%2f2018MS001537&partnerID=40&md5=61e590c4d3821a4e51e28cc929a5a1c2","Stochastic parameterizations are increasingly becoming skillful in representing unresolved atmospheric processes for global climate models. The stochastic multicloud model, used to simulate the life cycle of the three most common cloud types (cumulus congestus, deep convective, and stratiform) in tropical convective systems, is one example. In this model, these clouds interact with each other and with their environment according to intuitive-probabilistic rules determined by a set of predictors, depending on the large-scale atmospheric state and a set of transition time scale parameters. Here we use a Bayesian statistical method to infer these parameters from radar data. The Bayesian approach is applied to precipitation data collected by the Shared Mobile Atmospheric Research and Teaching Radar truck-mounted C-band radar located in the Maldives archipelago, while the corresponding large-scale predictors were derived from meteorological soundings taken during the Dynamics of the Madden-Julian Oscillation field campaign. The transition time scales were inferred from three different phases of the Madden-Julian Oscillation (suppressed, initiation, and active) and compared with previous studies. The performance of the stochastic multicloud model is also assessed, in a stand-alone mode, where the cloud model is forced directly by the observed predictors without feedback into the environmental variables. The results showed a wide spread in the inferred parameter values due in part to the lack of the desired sensitivity of the model to the predictors and the shortness of the training periods that did not include both active and suppressed convection phases simultaneously. Nonetheless, the resemblance of the stand-alone simulated cloud fraction time series to the radar data is encouraging. ©2019. The Authors."
"51663627700;7003480967;57212218812;57208709439;7003330586;16157484600;36718936000;57203177863;57208703258;8929266600;26027446700;7006204597;7006479378;57197316403;57204330159;57132504600;","Ice-nucleating particles in a coastal tropical site",2019,"10.5194/acp-19-6147-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065596210&doi=10.5194%2facp-19-6147-2019&partnerID=40&md5=d9536b4391cabbe073cf68a61389f2d5","Atmospheric aerosol particles that can nucleate ice are referred to as ice-nucleating particles (INPs). Recent studies have confirmed that aerosol particles emitted by the oceans can act as INPs. This very relevant information can be included in climate and weather models to predict the formation of ice in clouds, given that most of them do not consider oceans as a source of INPs. Very few studies that sample INPs have been carried out in tropical latitudes, and there is a need to evaluate their availability to understand the potential role that marine aerosol may play in the hydrological cycle of tropical regions.</p> <p>This study presents results from the first measurements obtained during a field campaign conducted in the tropical village of Sisal, located on the coast of the Gulf of Mexico of the Yucatan Peninsula in Mexico in January-February 2017, and one of the few data sets currently available at such latitudes (i.e., 21<span classCombining double low line""inline-formula"">ĝ</span>&thinsp;N). Aerosol particles sampled in Sisal are shown to be very efficient INPs in the immersion freezing mode, with onset freezing temperatures in some cases as high as <span classCombining double low line""inline-formula"">-3</span>&thinsp;<span classCombining double low line""inline-formula"">ĝ</span>C, similarly to the onset temperature from <i>Pseudomonas syringae</i>. The results show that the INP concentration in Sisal was higher than at other locations sampled with the same type of INP counter. Air masses arriving in Sisal after the passage of cold fronts have surprisingly higher INP concentrations than the campaign average, despite their lower total aerosol concentration.</p> <p>The high concentrations of INPs at warmer ice nucleation temperatures (<span classCombining double low line""inline-formula""><math xmlnsCombining double low line""http://www.w3.org/1998/Math/MathML"" idCombining double low line""M4"" displayCombining double low line""inline"" overflowCombining double low line""scroll"" dspmathCombining double low line""mathml""><mrow><mi>T</mi><mo>&gt;</mo><mo>-</mo><mn mathvariantCombining double low line""normal"">15</mn></mrow></math><span><svg:svg xmlns:svgCombining double low line""http://www.w3.org/2000/svg"" widthCombining double low line""41pt"" heightCombining double low line""10pt"" classCombining double low line""svg-formula"" dspmathCombining double low line""mathimg"" md5hashCombining double low line""ce91598f53adbff8662460797237c415""><svg:image xmlns:xlinkCombining double low line""http://www.w3.org/1999/xlink"" xlink:hrefCombining double low line""acp-19-6147-2019-ie00001.svg"" widthCombining double low line""41pt"" heightCombining double low line""10pt"" srcCombining double low line""acp-19-6147-2019-ie00001.png""/></svg:svg></span></span>&thinsp;<span classCombining double low line""inline-formula"">ĝ</span>C) and the supermicron size of the INPs suggest that biological particles may have been a significant contributor to the INP population in Sisal during this study. However, our observations also suggest that at temperatures ranging between <span classCombining double low line""inline-formula"">-20</span> and <span classCombining double low line""inline-formula"">-30</span>&thinsp;<span classCombining double low line""inline-formula"">ĝ</span>C mineral dust particles are the likely source of the measured INPs.</p>. © Author(s) 2019."
"9535769800;","Moisture transport over the western Maritime Continent during the 2015 and 2017 YMC Sumatra campaigns in global cloud-system-resolving simulations",2019,"10.2151/SOLA.2019-019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073018023&doi=10.2151%2fSOLA.2019-019&partnerID=40&md5=ba8d2447f8f87d457891877eb89c4428","Transport of moisture over the western Maritime Continent (MC) was examined using global cloud-system-resolving simulations for the Years of the Maritime Continent (YMC) field campaigns in 2015 and 2017, under peak El Niño and moderate La Niña conditions, respectively. We focused on the role of highand low-frequency variability in the moistening over land and ocean, and their relationship with intraseasonal oscillation (ISO) events. The period-mean profiles indicate moistening by lowfrequency upward motion in the deep troposphere and drying (moistening) in the lower (middle and upper) troposphere by highfrequency variability. The advection over ocean was greater in 2017 than in 2015, with the opposite occurring over land with smaller interannual differences. Over ocean, the roles of the highfrequency variability in the ISO life cycle, namely, the lower-tomiddle- tropospheric moistening (enhanced upward transport of moisture) during the preconditioning (active) phases of the ISO, were common in both years, while over land, the high-frequency effects were nearly in phase (not correlated) with the ISO in the 2015 (2017) case. These results highlight clear land-ocean contrasts in the sensitivity of local convection to the background state and its link with the ISO life cycle. © The Author(s) 2019."
"35113492400;57205154242;56611366900;55738957800;25823927100;19933330400;24765069600;35849722200;8557840900;14056120000;","Observational Relationship Between Entrainment Rate and Environmental Relative Humidity and Implications for Convection Parameterization",2018,"10.1029/2018GL080264","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058855629&doi=10.1029%2f2018GL080264&partnerID=40&md5=d6e2e723c87d108ccdae222577c8ebea","Entrainment rate is a critical but highly uncertain quantity in convective parameterizations; especially, the effects of environmental relative humidity on entrainment rate are controversial, or even opposite, in different studies. Analysis of aircraft observations of cumuli from the Routine AAF (Atmospheric Radiation Measurement [ARM] Aerial Facility) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) and Rain in Cumulus over the Ocean (RICO) field campaigns shows that entrainment rate is positively correlated with relative humidity. Physical analysis shows that higher relative humidity promotes entrainment by reducing buoyancy in the cloud cores and by weakening downdrafts near the cloud cores. The reduced buoyancy in the cloud cores and weakened downdrafts surrounding the cores further reduce updrafts in the cloud cores; the cloud cores with smaller updrafts are more significantly affected by their environment, resulting in larger entrainment rate. The relationship between entrainment rate and relative humidity is consistent with the buoyancy sorting concept widely used in convection parameterizations. The results provide reliable in situ observations to improve parameterizations of entrainment rate. ©2018. American Geophysical Union. All Rights Reserved."
"7102609908;38461378900;35407865200;36086352600;24399716000;57162264100;","Diurnal cycle over a coastal area of the Maritime Continent as derived by special networked soundings over Jakarta during HARIMAU2010",2018,"10.1186/s40645-018-0216-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054619234&doi=10.1186%2fs40645-018-0216-3&partnerID=40&md5=cbe735649ce6dde0af09a090b305739f","This study investigates the nature and mechanisms of the diurnal precipitation system over a coastal area of the Maritime Continent (MC) by utilizing the data from a field campaign, HARIMAU2010. During the 1-month campaign, diurnal cycles over Jakarta were well identified by special networked soundings and a C-band radar. Radar and satellites captured the convective-type heavy rains that appeared in the afternoon over the array, which were followed by stratiform-type precipitation during the night. Thermodynamic budget analyses were also performed using sounding data. The period-averaged vertical profiles of Q1 and Q2 indicate that diurnal precipitation acted as deep convection in the diabatic heating and drying. The diurnal composite of the obtained parameters revealed key processes such as (1) just before the onset of the afternoon convective rain, the lower troposphere was moistened by subarray-scale processes; (2) moistening of the troposphere continued during the convective heavy precipitation; (3) the stratiform rains during the night were partly maintained by consuming the pre-existing hydrometeor aloft; and (4) in the early morning, the clouds redeveloped over the ocean to produce precipitation as well as hydrometeor aloft. The possible physical processes promoting lower-tropospheric moistening before onset of the convective rain are also discussed. [Figure not available: see fulltext.]. © 2018, The Author(s)."
"42561044300;15318942300;57203859138;57203062420;6701413579;","Observations and Cloud-Resolving Modeling of Haboob Dust Storms Over the Arabian Peninsula",2018,"10.1029/2018JD028486","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056137658&doi=10.1029%2f2018JD028486&partnerID=40&md5=114404e59dd3e969fdbb81e69454c208","Strong mesoscale haboob dust storms in April 2007 in the central Arabian Peninsula were studied using the cloud-resolving Weather Research and Forecasting-Chemistry (WRF-Chem) modeling system and observations collected during an intensive atmospheric field campaign. The field campaign provided the valuable aircraft and Doppler weather radar measurements. Active convection persisted for several days during the study period. Dust generation was caused by both strong large-scale winds and locally produced density currents. Because of insufficient spatial resolution, the event was not resolved accurately by the conventional reanalyses. However, the WRF-Chem model did successfully capture the primary features of the convection, its location, and precipitation patterns. Although the amount of rainfall in the model was slightly underestimated compared to the satellite measurements, it was approximately double the rainfall in the reanalysis. The convection-associated dust outbreaks were simulated well, with the aerosols optical depth magnitude and the temporal variability being in good agreement with both the ground-based and satellite aerosol retrievals. The model captured the major dust generation patterns, transport pathways, and several of the largest haboobs identified from the satellite observations. About 25 Tg of dust was emitted in the Arabian Peninsula during the 10-day period. Approximately 40% of the locally deposited dust was subject to wet removal processes. During periods of high local dust production, the WRF-Chem model underestimated the PM10 mass concentration (associated mostly with dust particles larger than 3 μm in diameter) by nearly a factor of 2. This suggests that the current dust parameterizations, which prescribe the size distribution of the emitted dust, underestimate the number of large particles that increases at strong wind conditions. ©2018. The Authors."
"57188971800;7005054220;7102913661;55314628400;56591838400;7404327420;","Evaluation of Parameterized Convective Transport of Trace Gases in Simulation of Storms Observed During the DC3 Field Campaign",2018,"10.1029/2018JD028779","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054323400&doi=10.1029%2f2018JD028779&partnerID=40&md5=aed58f3e1c7c4129013f6097491c02ab","Deep convective transport of surface moisture and pollution from the planetary boundary layer to the upper troposphere and lower stratosphere affects the radiation budget and climate. This study uses cloud-parameterized Weather Research and Forecasting model coupled with Chemistry simulations to analyze the subgrid deep convective transport of CO at 12- and 36-km horizontal resolution in supercell and mesoscale convective systems observed during the 2012 Deep Convective Clouds and Chemistry field campaign and compares the simulation results with aircraft measurements and cloud-resolved simulations. The best Weather Research and Forecasting simulation of these storms was obtained with the use of the Grell-Freitas convective scheme. The default Weather Research and Forecasting model coupled with Chemistry subgrid convective transport scheme was replaced with a scheme to compute convective transport within the Grell-Freitas subgrid cumulus parameterization, which resulted in improved transport simulations. We examined the CO tendencies due to subgrid- and grid-scale convective transport. Results showed that the subgrid convective transport started earlier than the grid-scale convective transport. The subgrid-scale convective transport reached its maximum during the hour prior to the formation of the grid-scale constant-altitude detrainment layer. After that, both the subgrid- and grid-scale convective transport began to decrease. The subgrid-scale convective transport played a more significant role in the supercell case than the mesoscale convective system case. Subgrid contribution reached ~90% at the beginning of the storm and decreased to ~30% (17%) for the 36-km (12-km) domain 4 hr later. ©2018. American Geophysical Union. All Rights Reserved."
"21744073500;21742333400;15019752400;56472932500;7005219614;","ORACLE 2-D (v2.0): An efficient module to compute the volatility and oxygen content of organic aerosol with a global chemistry-climate model",2018,"10.5194/gmd-11-3369-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052094345&doi=10.5194%2fgmd-11-3369-2018&partnerID=40&md5=a6511b5a90f6724b9e7b4b02fd6a3c34","A new module, ORACLE 2-D, simulating organic aerosol formation and evolution in the atmosphere has been developed and evaluated. The module calculates the concentrations of surrogate organic species in two-dimensional space defined by volatility and oxygen-to-carbon ratio. It is implemented into the EMAC global chemistry-climate model, and a comprehensive evaluation of its performance is conducted using an aerosol mass spectrometer (AMS) factor analysis dataset derived from almost all major field campaigns that took place globally during the period 2001-2010. ORACLE 2-D uses a simple photochemical aging scheme that efficiently simulates the net effects of fragmentation and functionalization of the organic compounds. The module predicts not only the mass concentration of organic aerosol (OA) components, but also their oxidation state (in terms of O&thinsp;:&thinsp;C), which allows for their classification into primary OA (POA, chemically unprocessed), fresh secondary OA (SOA, low oxygen content), and aged SOA (highly oxygenated). The explicit simulation of chemical OA conversion from freshly emitted compounds to a highly oxygenated state during photochemical aging enables the tracking of hygroscopicity changes in OA that result from these reactions. ORACLE 2-D can thus compute the ability of OA particles to act as cloud condensation nuclei and serves as a tool to quantify the climatic impact of OA. © Author(s) 2018."
"35491260500;6506730508;7201804746;22933265100;7402942478;6602407753;35547214900;8147766700;","Dust impacts on the 2012 Hurricane Nadine track during the NASA HS3 field campaign",2018,"10.1175/JAS-D-17-0237.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049776429&doi=10.1175%2fJAS-D-17-0237.1&partnerID=40&md5=bf9e89795625b362d43da763d184157d","During the 2012 deployment of the NASA Hurricane and Severe Storm Sentinel (HS3) field campaign, several flights were dedicated to investigating Hurricane Nadine. Hurricane Nadine developed in close proximity to the dust-laden Saharan air layer and is the fourth-longest-lived Atlantic hurricane on record, experiencing two strengthening and weakening periods during its 22-day total life cycle as a tropical cyclone. In this study, the NASA GEOS-5 atmospheric general circulation model and data assimilation system was used to simulate the impacts of dust during the first intensification and weakening phases of Hurricane Nadine using a series of GEOS-5 forecasts initialized during Nadine's intensification phase (12 September 2012). The forecasts explore a hierarchy of aerosol interactions within the model: no aerosol interaction, aerosol-radiation interactions, and aerosol-radiation and aerosol-cloud interactions simultaneously, as well as variations in assumed dust optical properties. When only aerosol-radiation interactions are included, Nadine's track exhibits sensitivity to dust shortwave absorption, as a more absorbing dust introduces a shortwave temperature perturbation that impacts Nadine's structure and steering flow, leading to a northward track divergence after 5 days of simulation time. When aerosol-cloud interactions are added, the track exhibits little sensitivity to dust optical properties. This result is attributed to enhanced longwave atmospheric cooling from clouds that counters shortwave atmospheric warming by dust surrounding Nadine, suggesting that aerosol-cloud interactions are a more significant influence on Nadine's track than aerosol-radiation interactions. These findings demonstrate that tropical systems, specifically their track, can be impacted by dust interaction with the atmosphere. © 2018 American Meteorological Society."
"55746507000;7405489798;7003408439;7003554893;","Heating and moistening of the MJO during DYNAMO in ECMWF reforecasts",2018,"10.1175/JAS-D-17-0170.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047096310&doi=10.1175%2fJAS-D-17-0170.1&partnerID=40&md5=8ee91b12656d2c7b19895b04f975e4e7","Reforecasts produced by the ECMWF Integrated Forecast System (IFS) were used to study heating and moistening processes associated with three MJO events over the equatorial Indian Ocean during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign. Variables produced by and derived from the IFS reforecast (IFS-RF) agree reasonably well with observations over the DYNAMO sounding arrays, and they vary smoothly from the western to eastern equatorial Indian Ocean. This lends confidence toward using IFS-RF as a surrogate of observations over the equatorial Indian Ocean outside theDYNAMO arrays. The apparent heat source Q1 and apparent moisture sink Q2 produced by IFS are primarily generated by parameterized cumulus convection, followed by microphysics and radiation. The vertical growth of positive Q1 and Q2 associated with the progression of MJO convection can be gradual, stepwise, or rapid depending on the event and its location over the broader equatorial Indian Ocean. The time for convective heating and drying to progress from shallow (800 hPa) to deep (400 hPa) can be &lt; 1 to 6 days. This growth time of heating and drying is usually short for convective processes alone but becomes longer when additional microphysical processes, such as evaporative moistening below convective and stratiform clouds, are in play. Three ratios are calculated to measure the possible role of radiative feedback in the MJO events: amplitudes of radiative versus convective heating rates, changes in radiative versus convective heating rates, and diabatic (with and without the radiative component) versus adiabatic heating rates. None of them unambiguously distinguishes the MJO from non-MJO convective events. © 2018 American Meteorological Society."
"6506328135;7202048112;55476830600;34881780600;36908840200;","How Do Microphysical Processes Influence Large-Scale Precipitation Variability and Extremes?",2018,"10.1002/2017GL076375","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041743208&doi=10.1002%2f2017GL076375&partnerID=40&md5=3be0dcbae04d918d1a328582d07fb4c7","Convection permitting simulations using the Model for Prediction Across Scales-Atmosphere (MPAS-A) are used to examine how microphysical processes affect large-scale precipitation variability and extremes. An episode of the Madden-Julian Oscillation is simulated using MPAS-A with a refined region at 4-km grid spacing over the Indian Ocean. It is shown that cloud microphysical processes regulate the precipitable water (PW) statistics. Because of the non-linear relationship between precipitation and PW, PW exceeding a certain critical value (PWcr) contributes disproportionately to precipitation variability. However, the frequency of PW exceeding PWcr decreases rapidly with PW, so changes in microphysical processes that shift the column PW statistics relative to PWcr even slightly have large impacts on precipitation variability. Furthermore, precipitation variance and extreme precipitation frequency are approximately linearly related to the difference between the mean and critical PW values. Thus observed precipitation statistics could be used to directly constrain model microphysical parameters as this study demonstrates using radar observations from DYNAMO field campaign. ©2018. The Authors."
"57200334425;7006198994;6505932008;","Wind-flux feedbacks and convective organization during the november 2011 MJO event in a high-resolution model",2018,"10.1175/JAS-D-16-0346.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040953661&doi=10.1175%2fJAS-D-16-0346.1&partnerID=40&md5=636b0cc761d88c17d9f9dec6bef909fc","The November 2011 Madden-Julian oscillation (MJO) event during the Dynamics of the MJO (DYNAMO) field campaign is simulated with the Regional Atmospheric Modeling System (RAMS) cloud-resolving model to examine the relationship between precipitation and surface latent heat flux (LHFLX) for deep convective clusters within the MJO and to discern the importance of surface LHFLX for organizing MJO convection. First, a simulation similar in size to the DYNAMO northern sounding array was run with interactive surface fluxes. Composites for precipitation, surface LHFLX, wind speed, wind vectors, and near-surface specific humidity are described for various-sized convective clusters during different MJO regimes. The precipitation-LHFLX relationship generally evolves as follows for an individual cluster. About 2 h before cluster identification, the maximum LHFLX occurs upwind of maximum precipitation. As cluster identification time is approached, LHFLX and precipitation maxima become coincident. At and after the cluster is identified, maximum LHFLXs move downwind of the precipitation maximum with a local minimum in LHFLXs behind the precipitation maximum. Sensitivity simulations with spatially homogenized LHFLXs were then run to determine the impacts of local LHFLX feedbacks on convective organization. Using area-averaged convective versus stratiform precipitation fraction and a simple convective aggregation index to quantify organization, no systematic difference in convective organization was detected between the control and sensitivity simulations, suggesting that local LHFLX variability is not important to convective organization in this model. Implications of these results are discussed. © 2018 American Meteorological Society."
"57200338283;13608035400;57198129543;57199315807;56041136700;7102258993;20435708300;8597673800;25227465100;15822963700;","The impact of airborne radio occultation observations on the simulation of Hurricane Karl (2010)",2018,"10.1175/MWR-D-17-0001.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040937684&doi=10.1175%2fMWR-D-17-0001.1&partnerID=40&md5=b1d13a61f155acd09216ceb725234c60","This study evaluates, for the first time, the impact of airborne global positioning system radio occultation (ARO) observations on a hurricane forecast. A case study was conducted of Hurricane Karl during the Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) field campaign in 2010. The assimilation of ARO data was developed for the three-dimensional variational (3DVAR) analysis system of the Weather Research and Forecasting (WRF) Model version 3.2. The impact of ARO data on Karl forecasts was evaluated through data assimilation (DA) experiments of local refractivity and nonlocal excess phase (EPH), in which the latter accounts for the integrated horizontal sampling along the signal ray path. The tangent point positions (closest point of an RO ray path to Earth's surface) drift horizontally, and the drifting distance of ARO data is about 2 to 3 times that of spaceborne RO, which was taken into account in these simulations. Results indicate that in the absence of other satellite observations, the assimilation of ARO EPH resulted in a larger impact on the analysis than local refractivity did. In particular, the assimilation of ARO observations at the actual tangent point locations resulted in more accurate forecasts of the rapid intensification of the storm. Among all experiments, the best forecast was obtained by assimilating ARO data with the most accurate geometric representation, that is, the use of nonlocal EPH operators with tangent point drift, which reduced the error in the storm's predicted minimum sea level pressure (SLP) by 43% beyond that of the control experiment. © 2018 American Meteorological Society."
"57104690900;35209683700;57203558683;7406523040;","Hindcasting the Madden-Julian Oscillation With a New Parameterization of Surface Heat Fluxes",2017,"10.1002/2017MS001175","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034768056&doi=10.1002%2f2017MS001175&partnerID=40&md5=0cb62c6d91994e06cf84cca23d524b9f","The recently developed maximum entropy production (MEP) model, an alternative parameterization of surface heat fluxes, is incorporated into the Weather Research and Forecasting (WRF) model. A pair of WRF cloud-resolving experiments (5 km grids) using the bulk transfer model (WRF default) and the MEP model of surface heat fluxes are performed to hindcast the October Madden-Julian oscillation (MJO) event observed during the 2011 Dynamics of the MJO (DYNAMO) field campaign. The simulated surface latent and sensible heat fluxes in the MEP and bulk transfer model runs are in general consistent with in situ observations from two research vessels. Compared to the bulk transfer model, the convection envelope is strengthened in the MEP run and shows a more coherent propagation over the Maritime Continent. The simulated precipitable water in the MEP run is in closer agreement with the observations. Precipitation in the MEP run is enhanced during the active phase of the MJO with significantly reduced regional dry and wet biases. Large-scale ocean evaporation is stronger in the MEP run leading to stronger boundary layer moistening to the east of the convection center, which facilitates the eastward propagation of the MJO. © 2017. The Authors."
"57190422776;12800966700;57202425542;8657166100;","An inverse problem approach for the retrieval of ice particle mass from in situ measurements",2017,"10.1175/JTECH-D-17-0013.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023620400&doi=10.1175%2fJTECH-D-17-0013.1&partnerID=40&md5=ae34a4fc6beed6ff92665cc5a900e1d3","Mass-dimensional relationships (m-D) have been published for decades to characterize the microphysical properties of ice cloud particles. Classical m-D retrieval methods employ a simplifying assumption that restricts the form of the mass-dimensional relationship to a power law, an assumption that was proved inaccurate in recent studies. In this paper, a nonstandard approach that leverages optimal use of in situ measurements to remove the power-law constraint is presented. A model formulated as a linear system of equations relating ice particle mass to particle size distribution (PSD) and ice water content (IWC) is established, and the mass retrieval process consists of solving the inverse problem with numerical optimization algorithms. First, the method is applied to a synthetic crystal dataset in order to validate the selected algorithms and to tune the regularization strategy. Subsequently, the method is applied to in situ measurements collected during the High Altitude Ice Crystal-High Ice Water Content field campaigns. Preliminary results confirm the method is efficient at retrieving size-dependent masses from real data despite a significant amount of noise: the IWC values calculated from the retrieved masses are in good agreement with reference IWC measurements (errors on the order of 10%-15%). The possibility to retrieve ice particle size-dependent masses combined with the flexibility left for sorting datasets as a function of parameters such as cloud temperature, cloud type, or convective index makes this approach well suited for studying ice cloud microphysical properties. © 2017 American Meteorological Society."
"7202588306;56042321400;54408762200;55937215200;7202089880;55576725800;7405461406;","Modified gap fraction model of individual trees for estimating leaf area using terrestrial laser scanner",2017,"10.1117/1.JRS.11.035012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028540555&doi=10.1117%2f1.JRS.11.035012&partnerID=40&md5=f30a0e7f878db107f76a8088434873bd","Terrestrial laser scanners (TLS) have demonstrated great potential in estimating structural attributes of forest canopy, such as leaf area index (LAI). However, the inversion accuracy of LAI is highly dependent on the measurement configuration of TLS and spatial characteristics of the scanned tree. Therefore, a modified gap fraction model integrating the path length distribution is developed to improve the accuracy of retrieved single-tree leaf area (LA) by considering the shape of a single-tree crown. The sensitivity of TLS measurement configurations on the accuracy of the retrieved LA is also discussed by using the modified gap fraction model based on several groups of simulated and field-measured point clouds. We conclude that (1) the modified gap fraction model has the potential to retrieve LA of an individual tree and (2) scanning distance has the enhanced impact on the accuracy of the retrieved LA than scanning step. A small scanning step for broadleaf trees reduces the scanning time, the storage volume, and postprocessing work in the condition of ensuring the accuracy of the retrieved LA. This work can benefit the design of an optimal survey configuration for the field campaign. © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)."
"57193792502;57193793379;56249134600;56363987000;7201423091;57190209035;","Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles",2017,"10.5194/acp-17-4283-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016547959&doi=10.5194%2facp-17-4283-2017&partnerID=40&md5=df4a7bc5f824248f511e119ee23aa040","Spectral radiance measurements collected in nadir and sideward viewing directions by two airborne passive solar remote sensing instruments, the Spectral Modular Airborne Radiation measurement sysTem (SMART) and the Differential Optical Absorption Spectrometer (mini-DOAS), are used to compare the remote sensing results of cirrus optical thickness . The comparison is based on a sensitivity study using radiative transfer simulations (RTS) and on data obtained during three airborne field campaigns: the North Atlantic Rainfall VALidation (NARVAL) mission, the Mid-Latitude Cirrus Experiment (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems (ACRIDICON) campaign. Radiative transfer simulations are used to quantify the sensitivity of measured upward radiance with respect to ice crystal effective radius <i>r</i>eff, viewing angle of the sensor spectral surface albedo <i>±</i>, and ice crystal shape. From the calculations it is concluded that sideward viewing measurements are generally better suited than radiance data from the nadir direction to retrieve of optically thin cirrus, especially at wavelengths larger than <i>»</i>ĝ€‰Combining double low lineĝ€‰ĝ€900ĝ€nm. Using sideward instead of nadir-directed spectral radiance measurements significantly improves the sensitivity and accuracy in retrieving in particular for optically thin cirrus of ĝ€‰ĝ‰Currency signĝ€‰2. <br><br> The comparison of retrievals of based on nadir and sideward viewing radiance measurements from SMART, mini-DOAS and independent estimates of from an additional active remote sensing instrument, the Water Vapor Lidar Experiment in Space (Wales), shows general agreement within the range of measurement uncertainties. For the selected example a mean of 0.54ĝ€±ĝ€0.2 is derived from SMART, and 0.49ĝ€±ĝ€0.2 by mini-DOAS nadir channels, while Wales obtained a mean value of ĝ€‰Combining double low lineĝ€‰ĝ€0.32ĝ€±ĝ€0.02 at 532ĝ€nm wavelength, respectively. The mean of derived from the sideward viewing mini-DOAS channels is 0.26ĝ€±ĝ€0.2. For the few simultaneous measurements, the mini-DOAS sideward channel measurements systematically underestimate (ĝ'17.6ĝ€%) the nadir observations from SMART and mini-DOAS. The agreement between mini-DOAS sideward viewing channels and Wales is better, showing the advantage of using sideward viewing measurements for cloud remote sensing for ĝ€‰ĝ‰Currency signĝ€‰1. Therefore, we suggest sideward viewing measurements for retrievals of of thin cirrus because of the significantly enhanced capability of sideward viewing compared to nadir measurements."
"57190422776;12800966700;57202425542;8657166100;11440520800;57190425119;","Comparison of two retrieval techniques for ice particle mass from in-situ measurements: Implication for particle effective density and Median Mass Diameter",2017,"10.2514/6.2017-4245","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088773634&doi=10.2514%2f6.2017-4245&partnerID=40&md5=672d353740d831c3def1f3095c4caa3f","Ice particles in clouds are a known threat to commercial aviation. They can form areas with high ice water content at cruise altitudes where severe icing conditions may be sustained and not detected with current on-board technologies. In this article, a comparative study between two ice particle mass retrieval methods is presented. Both methods use in-situ measurements of the Particle Size Distribution (PSD) and Ice Water Content (IWC) as input to establish mass-diameter relationships (henceforth m-D). The first method follows the classical approach where the form of the m-D relationship is limited to power laws. The second method is based on an inverse problem approach: it leverages optimal use of in-situ measurements to waive the power law constraint. Both methods are tested on an in-situ measurement dataset collected during one research flight in an oceanic Mesoscale Convective System (MCS) with measured IWC values frequently exceeding 1.0 g.m-3. This flight was carried out in Darwin (Australia) area during the High Altitude Ice Crystals/High Ice Water Content 2014 international field campaign. Results show significant differences in crystal masses retrieved from both methods. The first outcome of the comparison is that IWC values calculated from the non-classical method are significantly closer to the measured IWC values than those calculated from the classical approach (the overall error is decreased by almost a factor 2). Another advantage of the non-classical approach is the increased latitude in the retrieval process to actually capture some size dependent microphysical processes. Preliminary results reveal different regimes in the variation of particle effective density with size. These variations are not captured by the classical mass retrieval methods where the m-D power law assumption restricts the shape of effective density versus size to a strictly decreasing polynomial curve. The Median Mass Diameter values (MMD) retrieved along flight path with both methods are found to differ: MMDs calculated from the inverse problem approach are consistently 20% smaller than those produced by the classical power law. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved."
"56573865400;","Influence of lee waves and rotors on the near-surface flow and pressure fields in the northern foreland of the Tatra Mountains",2016,"10.1002/met.1546","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956890270&doi=10.1002%2fmet.1546&partnerID=40&md5=85242d592aff1694794f7abc2d339e18","This study presents the results of a field campaign aimed at observing near-surface flow and pressure fields downwind of the Tatra Mountains. The general objective was to study low-level turbulence associated with lee waves and rotors and to improve weather forecasts for aviation. The main instrumentation consisted of a network of nine weather stations arranged as a transect perpendicular to the Tatra Mountains. The stations recorded the wind speed and direction (at 10 m), atmospheric pressure, temperature and humidity (at 2 m) for ∼2 years. Gliding flights and cloud cover observations using two digital sky cameras also formed part of the campaign. The measurements were supported by data from atmospheric soundings in Poprad (Slovakia) and satellite images provided by the Moderate Resolution Imaging Spectroradiometer (MODIS). During a stable southerly flow, episodes of flow separation were observed, which are associated with lee-wave and rotor activity aloft. Based on data from the selected period, surface-pressure perturbations arranged as alternate positive and negative anomalies with extreme values of up to ∼0.7 hPa were detected. Positive (negative) anomalies are assumed to be a response of the surface-pressure field under the influence of descending (ascending) wave or rotor currents because of the downward (upward) component of the air movement in the atmosphere. The relationship between the decreasing magnitudes of the pressure perturbations with the distance from the Tatra Mountains was exposed. It was also possible to demonstrate the dependence of the position and intensity of pressure anomalies in relation to changes in wind conditions. © 2016 Royal Meteorological Society."
"37065453400;7006083502;7003495982;7003324794;","The impact of the QNSE-EDMF scheme and its modifications on boundary layer parameterization in WRF: Modelling of CASES-97",2016,"10.1002/qj.2723","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969326674&doi=10.1002%2fqj.2723&partnerID=40&md5=bf2e752b2d608d656ddb48179265923f","In recent years, many eddy-diffusivity mass-flux (EDMF) planetary boundary layer (PBL) parametrizations have been introduced. Yet most validations are based on idealized set-ups and/or single-column models. To address this gap, this article focuses on the effect the mass-flux part has on the performance in the Quasi-Normal Scale Elimination-EDMF (QNSE-EDMF) PBL scheme in the Weather Research and Forecasting (WRF) model by comparing the results to observations from the CASES-97 field campaign. In addition, two refined versions, one introducing the parametrized clouds to the WRF radiation scheme, and the second adding a different entrainment formulation, have been evaluated. The introduction of mass flux reduced errors in the average moisture profile, but virtual temperature and wind speed profiles did not change as much. The modelled mixed-layer depth, while still low compared to observations, was closer to observed values with the addition of mass flux. The major changes in the virtual potential temperature flux profiles were an increase in entrainment ratios and a slight decrease in surface values. Allowing for biases in the observed fluxes, modelled and observed flux profiles had a similar shape. However, the agreement among the modelled and between the modelled and observed water-vapour flux profiles and vertical flux divergence was often poor, a likely result of the model's failure to capture the timing of the morning boundary-layer water-vapour maximum. Further, both virtual potential temperature and water-vapour flux profiles display spurious spikes attributed to the way the non-local and local terms interact in the model. Adding mass-flux-based clouds to the radiation calculation improved the time-and space-averaged modelled incoming short-wave flux. The choice of the representation for entrainment/detrainment often affected the results to the same extent as adding mass flux. © 2016 Royal Meteorological Society."
"7102743829;6506537159;","A PDF-based formulation of microphysical variability in cumulus congestus clouds",2016,"10.1175/JAS-D-15-0129.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957713954&doi=10.1175%2fJAS-D-15-0129.1&partnerID=40&md5=4eb9d91cdf0e86b6ed34258c376f4091","Calculating unbiased microphysical process rates over mesoscale model grid volumes necessitates knowledge of the subgrid-scale (SGS) distribution of variables, typically represented as probability distribution functions (PDFs) of the prognostic variables. In the 2014 Journal of the Atmospheric Sciences paper by Kogan and Mechem, they employed large-eddy simulation of Rain in Cumulus over the Ocean (RICO) trade cumulus to develop PDFs and joint PDFs of cloud water, rainwater, and droplet concentration. In this paper, the approach of Kogan and Mechem is extended to deeper, precipitating cumulus congestus clouds as represented by a simulation based on conditions from the TOGA COARE field campaign. The fidelity of various PDF approximations was assessed by evaluating errors in estimating autoconversion and accretion rates. The dependence of the PDF shape on grid-mean variables is much stronger in congestus clouds than in shallow cumulus. The PDFs obtained from the TOGA COARE simulations for the calculation of accretion rates may be applied to both shallow and congestus cumulus clouds. However, applying the TOGA COARE PDFs to calculate autoconversion rates introduces unacceptably large errors in shallow cumulus clouds, thus precluding the use of a ""universal"" PDF formulation for both cloud types. © 2016 American Meteorological Society."
"55986212400;7101964663;56919728400;56919645600;","Satellite and aircraft observations of the eyewall replacement cycle in Typhoon Sinlaku (2008)",2015,"10.1175/MWR-D-15-0066.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84945156508&doi=10.1175%2fMWR-D-15-0066.1&partnerID=40&md5=819b77108ab5d4d27707e01f638fb560","Satellite and aircraft observations of the concurrent evolution of cloud-top brightness temperatures (BTs) and the surface and flight-level wind fields were examined before and during an eyewall replacement cycle (ERC) in Typhoon Sinlaku (2008) as part of The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC) and the Tropical Cyclone Structure 2008 (TCS08) field campaign. The structural evolution of deep convection through the life cycle of the ERC was clearly evident in the radial variation of positive water vapor (WV) minus infrared (IR) brightness temperature differences over the 96-h period. Within this framework, the ERC was divided into six broadly defined stages, wherein convective processes (including eyewall development and decay) were analyzed and then validated using microwave data. Dual maxima in aircraft wind speeds and geostationary satellite BTs along flight transects through Sinlaku were used to document the temporal evolution of the ERC within the TC inner core. Negative correlations were found between IR BTs and surface wind speeds, indicating that colder cloud tops were associated with stronger surface winds. Spatial lags indicated that the strongest surface winds were located radially inward of both the flight-level winds and coldest cloud tops. Finally, timing of the ERC was observed equally in IR and WV minus IR (WVIR) BTs with one exception. Decay of the inner eyewall was detected earlier in the WVIR data. These findings highlight the potential utility of WVIR and IR BT radial profiles, particularly so for basins without active aircraft weather reconnaissance programs such as the western North Pacific. � 2015 American Meteorological Society."
"7404350742;6701858531;7102965584;7402115506;36598934900;13408938100;57208760036;57188689884;57188679943;7003448155;","São Paulo lightning mapping array (SP-LMA): Network assessment and analyses for intercomparison studies and GOES-R proxy activities",2014,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086812113&partnerID=40&md5=0f6035c529acf01e82f002474be3caea","A 12 station Lightning Mapping Array (LMA) network was deployed during October 2011 in the vicinity of São Paulo, Brazil (SP-LMA) to contribute total lightning measurements to an international field campaign [CHUVA - Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)]. The SP-LMA was operational from November 2011 through March 2012 during the Vale do Paraíba campaign. Sensor spacing was on the order of 15-30 km, with a network diameter on the order of 40-50km. The SP-LMA provides good 3-D lightning mapping out to 150 km from the network center, with 2-D coverage considerably farther. In addition to supporting CHUVA science/mission objectives, the SP-LMA is supporting the generation of unique proxy data for the Geostationary Lightning Mapper (GLM) and Advanced Baseline Imager (ABI), on NOAA's Geostationary Operational Environmental Satellite-R (GOES-R: scheduled for a 2015 launch). These proxy data will be used to develop and validate operational algorithms so that they will be ready to use on “day1” following the GOES-R launch. As the CHUVA Vale do Paraíba campaign opportunity was formulated, a broad community-based interest developed for a comprehensive Lightning Location System (LLS) intercomparison and assessment study, leading to the participation and/or deployment of eight other ground-based networks and the space-based Lightning Imaging Sensor (LIS). The SP-LMA data is being intercompared with lightning observations from other deployed lightning networks to advance our understanding of the capabilities/contributions of each of these networks toward GLM proxy and validation activities. This paper addresses the network assessment including noise reduction criteria, detection efficiency estimates, and statistical and climatological (both temporal and spatially) analyses for intercomparison studies and GOES-R proxy activities. © International Conference on Atmospheric Electricity, ICAE 2014"
"7404830554;57201282288;6506175295;7004572420;17436105100;55532002300;35422648700;","Aerosol characterization by dual-wavelength polarization Lidar measurements over Kochi, Japan during the warm seasons of 2008 to 2010",2013,"10.2151/jmsj.2013-605","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896343268&doi=10.2151%2fjmsj.2013-605&partnerID=40&md5=9f7b19423ada128030ae0b550a1f8dc8","Dual-wavelength polarization lidar measurements of aerosols and clouds were conducted over Kochi (33.6°N, 133.5°E) during the warm-season field campaign of the Japanese Cloud Seeding Experiment Precipitation Augmentationproject in June -July of 2008 to 2010. Lidar-derived aerosol optical properties were compared with the microphysical properties obtained with aircraft-based instruments to evaluate the utility of the lidar data for characterizing the background aerosol, which critically affects the success of cloud seeding to enhance precipitation. The results showed that the particle backscattering coefficient at 532 nm correlated well with the number concentration of aerosols with diameter (Dp) exceeding 0.3 μm (correlationcoefficie t, r = 0.89), whereas the correlationof the backscattering coefficient with the number concentration of cloud condensation nuclei (CCN), activated at a water saturationof 0.7% or 1.0%, was lower (r = 0.74) because of the low sensitivity of the lidar system to the small CCN particles (Dp ≈ 0.04 μm). Inlidar data collected on1 July 2008, the depolarizationratio (δ) was high (20%), an d the backscatter wavelength exponent (å)waslow(&lt;0.5)betweenaltitudesof4and6km,andtheywerelow(δ=2.5%) and moderate (å = 0.7) between 0.5 and 1.0 km, suggesting the presence of supermicrometer-sized, non-spherical particles in the upper altitude range and a predominance of submicrometer-sized particles and/or spherical particles in the lower altitude range. These values were consistent with aircraft measurements, indicating the presence of supermicrometer-sized mineral particles in the upper altitude range and a predominance of submicrometer-sized sulfates and supermicrometer-sized sea-salt droplets at lower altitude. Our results demonstrate the utility of lidar data for aerosol characterization, although the further improvement of CCN characterization by lidar is necessary. © 2013, Meteorological Society of Japan."
"7004901816;","Looking skyward to study ecosystem carbon dynamics",2012,"10.1029/2012EO140002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859711266&doi=10.1029%2f2012EO140002&partnerID=40&md5=a9c66fda2db611d1a449f872a118edf9","Between May and October 2011 the U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program, conducted a field campaign at the ARM Southern Great Plains site in north central Oklahoma to evaluate a new instrument for quantitative image-based monitoring of sky conditions and solar radiation. The High Dynamic Range All-Sky Imaging System (HDR-ASIS) was developed by USGS to support studies of cloud- and aerosol-induced variability in the geometric properties of solar radiation (the sky radiance distribution) and its effects on photosynthesis and uptake of carbon dioxide (CO 2) by terrestrial ecosystems. Under a clean, cloudless atmosphere when the Sun is above the horizon, most of the solar radiation reaching an area of the Earth's surface is concentrated in a beam coming directly from the Sun; a relatively small proportion arrives as diffuse radiation from the rest of the sky. Clouds and atmospheric aerosols cause increased scattering of the beam radiation, which increases the proportion of diffuse radiation at the surface."
"55839333400;6603580234;7202887238;7006068346;","Water quality assessment in the application of stormwater reuse for irrigating public lands",2008,"10.2166/wqrj.2008.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952586891&doi=10.2166%2fwqrj.2008.018&partnerID=40&md5=e32fff6823e05add33bd397c5c098909","Stormwater reuse for irrigating public lands presents a viable option for reducing potable water demand in urban settings. However, stormwater generally contains high pollutant levels, which may cause adverse effects on public health and the environment. Water quality in a stormwater retention pond in the City of Calgary, Alberta, was examined in order to assess the feasibility of reusing stormwater for irrigation purposes. Field campaigns were conducted in the 2004, 2005, and 2006 irrigation seasons. The water quality data indicated that the pond water quality generally satisfies the requirements for stormwater recycled as irrigation water. Relationships between stormwater quality and climatological variables were investigated using correlation and regression analysis. Their correlations suggest that intermittent rain events contribute to elevated microbial levels and total suspended solids (TSS). Other climatological variables-air temperature, cloud cover, wind speed, and relative humidity-are also correlated with certain water quality parameters including fecal coliform (FC), TSS, nutrients, and conductivity. Formulated regression equations demonstrate good predictions of observed FC and TSS using climatological variables. Results showing stormwater quality as a function of climatological variables imply that climate change might have potential influence on stormwater quality. © 2008, CAWQ."
"6506354630;7003507545;","Interactive aspects of the Indian and the African summer monsoon systems",2007,"10.1007/s00024-007-0240-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548297910&doi=10.1007%2fs00024-007-0240-5&partnerID=40&md5=31d245d5220d0a910de1ba04c758bc55","This study addresses an understanding of the possible mutual interactions of sub-seasonal variability of the two neighboring regional monsoon systems through data analysis. The NCEP/NCAR re-analysis and OLR data for three years was used to reveal the large-scale organization of convective episodes on synoptic (∼5 days) and low frequency (15-50 day) scales. It is found that synoptic scale organization over both the sectors is influenced by the eastward migration of large-scale convective episodes associated with the Madden Julian Oscillation (MJO) on the low frequency scale. The organization of convection associated with the African monsoon on the synoptic scale is influenced by the pulsatory character of lower mid-troposphere and upper troposphere wind regimes moving westward over the African sector. Over the Indian region formation of low pressure areas and depressions in the monsoon trough occur in an overlapping manner under an envelope of low frequency seasonal oscillation. We have also found some correspondence between the summer monsoon rainfall over tropical North Africa and India on a decadal basis, which would suggest a common mode of multi-decadal variability in the two monsoon systems. The study points out the need to organize simultaneous field campaigns over the Indian and the African monsoon regions so as to bring out observational features of possible interactions between the two neighboring systems, which could then be validated through modeling studies. © Birkhäuser Verlag, Basel, 2007."
"8517033900;26643530600;7102063963;7402307060;6602873932;35413553600;","Evaluation of AIRS cloud properties using MPACE data",2005,"10.1029/2005GL024400","https://www.scopus.com/inward/record.uri?eid=2-s2.0-32644434906&doi=10.1029%2f2005GL024400&partnerID=40&md5=3185ecff874716a86a4d9ec13c4636c1","Retrieval of cloud properties from the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua satellite has been investigated. The cloud products from the collocated MODerate resolution Imaging Spectroradiometer (MODIS) data are used to characterize the AIRS sub-pixel cloud information such as cloud phase cloud coverage, and cloud layer information. A Minimum Residual (MR) approach is used to retrieve cloud microphysical properties once the cloud top pressure (CTP) and effective cloud amount (ECA) am determined from AM CO2 absorption channels between 720 and 790 cm-1. The cloud mierophysical properties can be retrieved by minimizing the difibrences between the observations and the calculations using AIRS longwave window channels between 790 and 1130 cm-1. AIRS is used to derive cloud properties during the Mixed Phase Arctic Cloud Experiment (MPACE) field campaign. Comparison with measurements obtained from lidar data is made for a ten day, showing that AIRS cloud property retrievals agree with in situ lidar observations. Due to the large solar zenith angle, the MODIS operational retrieval approach is not able to provide cloud microphysics north of Barrow, Alaska; however, AIRS provides cloud microphysical properties with its high spectral resolution IR measurements. Copyright 2005 by the American Geophysical Union."
"7003397735;6506743029;","Temperatures, densities, and winds in the high latitude (78°N) mesosphere",2003,"10.1016/S0273-1177(03)00408-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0242414612&doi=10.1016%2fS0273-1177%2803%2900408-3&partnerID=40&md5=56b0467e297069de93815b133616c15a","A field campaign called ROMA (""Rocket borne Observations in the Middle Atmosphere"") was conducted in 2001 close to Longyearbyen (Spitsbergen, 78°N) with temperature, density, and wind measurements by meteorological rockets and ground-based detection of noctilucent clouds (NLC) by lidar and polar mesosphere summer echoes (PMSE) by radar. A summary of the temperature data has been published recently [Lübken and Müllemann, 2003]. Here we present a detailed comparison of temperatures and densities with empirical models (CIRA, MSIS) and with measurements at other latitudes. We also present falling sphere winds. It is very cold in the upper mesosphere during the summer season, cold enough for water ice particles to exist, i. e., the degree of saturation is larger than unity assuming reasonable [H 2 O] values. Generally, PMSE and NLC are found at altitudes with super-saturation. There are striking differences and similarities between temperatures and densities at Longyearbyen, empirical reference models, and measurements at other latitudes, respectively. For example, around the mesopause in summer, temperatures are smaller by 6-9 K in Longyearbyen compared to Andøya (69°N). Much larger differences are observed relative to CIRA: temperatures are smaller by up to 20 K and mass densities in the upper mesosphere are almost 50% smaller compared to CIRA-1986. In the lower and middle atmosphere, temperatures and densities are very similar to values at Andøya and to empirical models. Zonal winds are westward in the mesosphere and generally agree with CIRA-1986, both in direction and magnitude. Meridional winds are smaller than zonal winds. © 2003 Published by Elsevier Ltd. All rights reserved."
"57210836958;7601314333;7101814956;7409077047;","The MODIS land-surface temperature products for regional environmental monitoring and global change studies",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036401939&partnerID=40&md5=1d180decf4abdbc9c6ddac9ae9fb9b40","This paper presents the status of MODIS Land-Surface Temperature (LST) standard products. The accuracy of daily MODIS LST products has been validated in eighteen clearsky cases with in-situ measurement data collected in field campaigns in 2000 and 2001, being better than 1K in the range from 263K to 322K. Techniques to remove the LSTs contaminated with cloud effects are discussed in order to make the MODIS LST products suitable for regional and global change studies."
"10640183500;7202315227;7004898341;","Comparison of the concentrations of chemical components in cloudwater samples collected during four different field campaigns",2001,"10.1023/A:1012240431098","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034754350&doi=10.1023%2fA%3a1012240431098&partnerID=40&md5=039cd10f3c507b5d17034cba419a5f40","In this study, the results of four different field experiments concerning the speciation of iron and the concentrations of some other chemical compounds in cloudwater samples are compared to one-another. Hydrogen peroxide concentrations were higher during campaigns, conducted at sites not much influenced by anthropogenic emissions as compared to those conducted at more polluted areas. In contrast, percentages of S(IV) in the cloudwater were lowest at the rural sites and highest at the sites polluted by human activities, indicating a consumption of hydrogen peroxide in the oxidation reaction with S(IV). The concentration of dissolved iron was observed to correlate with the percentage of S(IV), which may be an essential point for the reductive dissolution of oxidic iron compounds of the aerosol particles. As far as the speciation of the dissolved iron is concerned, it became obvious that the percentage of Fe(III) is anticorrelated to the concentration of dissolved iron. This clearly shows the important effect of the chemical and/or photo reductive ways of dissolving the iron(III)-compounds from the aerosol particles. However, a correlation between the pH-value and hydrogen peroxide was observed."
"7102122493;7102591209;","A survey of tropical cirrus particle size and shape using ATSR-2 visible/near-infrared data",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-5244285916&partnerID=40&md5=ea93f5495b3d2e54b009baa0247873b8","The visible (0.55, 0.67 and 0.87 μm) and near-infrared (1.6 μm) channels of the Along Track Scanning Radiometer-2 are capable of determining the optical depth and the size of cirrus cloud crystals. An addition, the along track view of the ATSR gives some information on the crystal shape and allows cloud height to be determined. Cloud temperature can be derived from the thermal channels (11 and 12 μm). We briefly describe the retrieval of these cloud properties, using representative ice crystal phase functions assuming hexagonal columns and polycrystals, from the ATSR-2 data. We present results of a preliminary survey of cirrus cloud properties using 35 selected scenes of diverse convective activity from the Western Tropical Pacific. The cloud top temperatures of our survey are consistent with the CEPEX field campaign which measured ice crystal shape and size. The conclusions from this limited study are; 1) polycrystal scattering phase functions adequately explain the ATSR-2 dual-view reflectance measurements in 60-80% cases; the remainder are not well explained by column phase functions, 2) crystal sizes decrease with cloud temperature at a rate of around 1μm per °C to asymptote around 50μm at -80°C, 3) crystal sizes are consistantly independent of cloud optical depth and 4) lapse rates for the lower troposphere lie between dry and wet adiabatics but upper level cloud temperatures often appear 'too high'."
"55345946200;8724962900;56724696200;8538154900;55672545600;55338801300;24554420100;57188570624;","Performance of the NCMRWF convection-permitting model during contrasting monsoon phases of the 2016 INCOMPASS field campaign",2020,"10.1002/qj.3689","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074534126&doi=10.1002%2fqj.3689&partnerID=40&md5=286e824bd28de6b3688320a83b92629e","This study uses INCOMPASS aircraft, radiosonde and satellite observations for verifying hydrometeors and associated state variables predicted by the regional model of the NCMRWF (NCUM-R) for contrasting phases of the 2016 monsoon. INCOMPASS flights B957 and B975 took place between Lucknow in northern India and Bhubaneswar near the east coast, and represent a contrast between dry pre-monsoon and active monsoon conditions, respectively. A moist profile above 4 km in Bhubaneswar measured on B957 showed a dry-air intrusion being eroded by mid-level clouds, whereas the Lucknow profile showed a drier, pre-monsoon profile. Aerosol extinction coefficient and cloud-top height measured using lidar showed an influx of continental aerosol, and intermittent multiple clouds below the aircraft in the mid-troposphere and boundary layer. Measurements from B975 match well with cyclonic wind patterns estimated from satellite observations and the convective tendency represented in radiosonde profiles. Extensive clouds were detected below 5 km during the active monsoon. Two model formulations for cloud representation (prognostic cloud and prognostic condensate, PC2, and diagnostic schemes, Diag) are compared with observations during the campaign. Vertical structures of state variables from both schemes are generally in agreement along the flight tracks. Surface energy budget and cloud diagnoses indicate higher cloud cover in Diag consistent with lower surface temperatures through reduced surface downwelling short-wave flux than in PC2, while the latent-heat flux is found to be insensitive to cloud scheme chosen. In-cloud water content is larger in PC2 for lower cloud fraction, and the autoconversion process is faster with respect to Diag. Higher total condensed-water content in the model with respect to aircraft measurements and an enhanced light precipitation bias with respect to satellite data is common to both cloud schemes. Further work to improve the representation of clouds and precipitation for the tropical implementation of the model is clearly warranted. © 2019 Royal Meteorological Society"
"57196051515;35578617800;57214074892;53979433000;6507504802;57004919300;55054479400;6602554025;55907766000;9041987100;56177107100;","Biogenic volatile organic compounds (BVOCs) reactivity related to new particle formation (NPF) over the Landes forest",2020,"10.1016/j.atmosres.2020.104869","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078087830&doi=10.1016%2fj.atmosres.2020.104869&partnerID=40&md5=afa095274bf82fed7816139a198f023d","Atmospheric particles play a major role in both air quality and climate change. Formation of secondary particles in the atmosphere has been observed over many different environments and is believed to provide up to half of the atmospheric cloud condensation nuclei (CCN) at a global scale. However, high uncertainties are still remaining in the description of mechanisms involved in new particle formation (NPF). Especially, more evidences of the implication of biogenic volatile organic compounds (BVOCs) in NPF from field studies are still needed. To investigate this question, two field campaigns have been set up during July 2014 and July 2015, in the French Landes forest (south west of France). Summer 2015 was characterized by a strong hydric stress, whereas summer 2014 was rainy. In 2015, frequent nocturnal NPF was observed, reaching a frequency of occurrence of ~55% of the nights, while only one event was observed in 2014. In July 2015, monoterpene mixing ratios (dominated by α- and β-pinene) were higher, mostly due to high ambient temperatures and drought. A focus was made on the 2015 field campaign, where NPF was mostly observed. The mean diurnal variation of the ratio between α- and β-pinene mixing ratios highlighted in-canopy reactivity of monoterpenes with ozone in the early night. This hypothesis was reinforced by the increasing gas phase levels of pinonaldehyde and nopinone, the main first-generation products arising from α- and β-pinene ozonolysis, at night, before NPF started. It strongly suggests that monoterpene oxidation further generated very-low volatility gases involved in NPF. This finding is also supported by the high concentrations of the SOA traditional biogenic tracers, e.g. pinic and pinonic acids, quantified in the particulate phase. The role of BVOCs in NPF is thus highlighted, as well as the importance of nighttime NPF. © 2020 Elsevier B.V."
"56522768500;6602999057;56522444900;24335183800;57195673296;7202060229;","The influence of DACCIWA radiosonde data on the quality of ECMWF analyses and forecasts over southern West Africa",2020,"10.1002/qj.3763","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080987081&doi=10.1002%2fqj.3763&partnerID=40&md5=79b295387bd9d86d17e51887684e8988","During the DACCIWA (Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa) field campaign ∼900 radiosondes were launched from 12 stations in southern West Africa from 15 June to 31 July 2016. Subsequently, data-denial experiments were conducted using the Integrated Forecasting System of the European Centre for Medium-range Weather Forecasts (ECMWF) to assess the radiosondes' impact on the quality of analyses and forecasts. As observational reference, satellite-based estimates of rainfall and outgoing long-wave radiation (OLR) as well as the radiosonde measurements themselves are used. With regard to the analyses, the additional observations show positive impacts on winds throughout the troposphere and lower stratosphere, while large lower-tropospheric cold and dry biases are hardly reduced. Nonetheless, downstream, that is farther inland from the radiosonde stations, we find a significant increase (decrease) in low-level night-time temperatures (monsoon winds) when incorporating the DACCIWA observations, suggesting a possible linkage via weaker cold air advection from the Gulf of Guinea. The associated lower relative humidity leads to reduced cloud cover in the DACCIWA analysis. Closer to the coast and over Benin and Togo, DACCIWA observations increase low-level specific humidity and precipitable water, possibly due to changes in advection and vertical mixing. During daytime, differences between the two analyses are generally smaller at low levels. With regard to the forecasts, the impact of the additional observations is lost after a day or less. Moderate improvements occur in low-level wind and temperature but also in rainfall over the downstream Sahel, while impacts on OLR are ambiguous. The changes in precipitation appear to also affect high-level cloud cover and the tropical easterly jet. The overall rather small observation impact suggests that model and data assimilation deficits are the main limiting factors for better forecasts in West Africa. The new observations and physical understanding from DACCIWA can hopefully contribute to reducing these issues. © 2020 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"6506286986;6602999057;56522444900;7202060229;8946494600;26659013400;57195673296;57193439898;57189498750;","An evaluation of operational and research weather forecasts for southern West Africa using observations from the DACCIWA field campaign in June–July 2016",2020,"10.1002/qj.3729","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079059722&doi=10.1002%2fqj.3729&partnerID=40&md5=5a7f11b80b45293a7f1cdbd890618556","Reliable and accurate weather forecasts, particularly those of rainfall and its extremes, have the potential to improve living conditions in densely populated southern West Africa (SWA). The limited availability of observations has long impeded a rigorous evaluation of current state-of-the-art forecast models. The field campaign of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project in June–July 2016 has created an unprecedentedly dense set of measurements from surface stations and radiosondes. Here we present results from a comprehensive evaluation of both numerical model forecasts and satellite products using these data on a regional and local level. Results reveal a substantial observational uncertainty showing considerable underestimations in satellite estimates of rainfall and low-cloud cover with little correlation at the local scale. Models have a dry bias of 0.1–1.9 (Formula presented.) in rainfall and too low column relative humidity. They tend to underestimate low clouds, leading to excess surface solar radiation of 43 (Formula presented.). Remarkably, most models show some skill in representing regional modulations of rainfall related to synoptic-scale disturbances, while local variations in rainfall and cloudiness are hardly captured. Slightly better results are found with respect to temperature and for the post-onset rather than for the pre-onset period. Delicate local features such as the Maritime Inflow phenomenon are also rather poorly represented, leading to too cool, dry and cloudy conditions at the coast. Differences between forecast days 1 and 2 are relatively small and hardly systematic, suggesting a relatively quick error saturation. Using explicit convection leads to more realistic spatial variability in rainfall, but otherwise no marked improvement. Future work should aim at improving the subtle balance between the diurnal cycles of low clouds, surface radiation, the boundary layer and convection. Further efforts are also needed to improve the observational system beyond field campaign periods. © 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"55372899300;6602137800;13403957300;56061814400;15047918700;57202922977;7003359002;6603133611;14321072000;7401793588;35405390200;57213358341;35232912700;57200790124;57208460143;57217266035;24722339600;7003334425;7003899504;6507426741;57214890938;57204921091;","Above-cloud aerosol optical depth from airborne observations in the southeast Atlantic",2020,"10.5194/acp-20-1565-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079373220&doi=10.5194%2facp-20-1565-2020&partnerID=40&md5=c77ea1495587344e6f22ca91fcfa5df5","The southeast Atlantic (SEA) region is host to a climatologically significant biomass burning aerosol layer overlying marine stratocumulus. We present the first results of the directly measured above-cloud aerosol optical depth (ACAOD) from the recent ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) airborne field campaign during August and September 2016. In our analysis, we use data from the Spectrometers for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR) instrument and found an average ACAOD of 0.32 at 501 nm (range of 0.02 to 1.04), with an average Ångström exponent (AE) above clouds of 1.71. The AE is much lower at 1.25 for the full column (including below-cloud-level aerosol, with an average of 0.36 at 501 nm and a range of 0.02 to 0.74), indicating the presence of large aerosol particles, likely marine aerosol, in the lower atmospheric column. The ACAOD is observed from 4STAR to be highest near the coast at about 12 S, whereas its variability is largest at the southern edge of the average aerosol plume, as indicated by 12 years of MODIS observations. In comparison to MODISderived ACAOD and long-term fine-mode plume-average AOD along a diagonal routine track extending out from the coast of Namibia, the directly measured ACAOD from 4STAR is slightly lower than the ACAOD product from MODIS. The peak ACAOD expected from MODIS AOD retrievals averaged over a long term along the routine diagonal flight track (peak of 0.5) was measured to be closer to coast in 2016 at about 1.5-4 E, with 4STAR ACAOD av erages showing a peak of 0.42. When considering the full observation set over the SEA, by spatially binning each sampled AOD, we obtain a geographically representative mean ACAOD of 0.37. Vertical profiles of AOD showcase the variability in the altitude of the aerosol plume and its separation from the cloud top. We measured larger AOD at a high altitude near the coast than farther from the coast, while generally observing a larger vertical gap farther from the coast. Changes in AOD with altitude are correlated with carbon monoxide, a gas tracer of the biomass burning aerosol plume. Vertical extent of gaps between aerosol and cloud show a wide distribution, with a near-zero gap being most frequent. The gap distribution with longitude is observed to be largest at about 7 E, farther from coast than expected from previous studies. © 2020 Author(s)."
"7202119915;57197432263;6701858531;55745699700;35239364700;55745595300;7102965584;14019342100;7402115506;57194870132;57218545856;6603677704;","The relampago lightning mapping array: Overview and initial comparison with the geostationary lightning mapper",2020,"10.1175/JTECH-D-20-0005.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089524294&doi=10.1175%2fJTECH-D-20-0005.1&partnerID=40&md5=188b34624ad64003e9db8cc8f9434bf0","During November 2018–April 2019, an 11-station very high frequency (VHF) Lightning Mapping Array (LMA) was deployed to Córdoba Province, Argentina. The purpose of the LMA was validation of the Geostationary Lightning Mapper (GLM), but the deployment was coordinated with two field campaigns. The LMA observed 2.9 million flashes ($ five sources) during 163 days, and level-1 (VHF locations), level-2 (flashes classified), and level-3 (gridded products) datasets have been made public. The network’s performance allows scientifically useful analysis within 100 km when at least seven stations were active. Careful analysis beyond 100 km is also possible. The LMA dataset includes many examples of intense storms with extremely high flash rates (.1s21), electrical discharges in overshooting tops (OTs), as well as anomalously charged thunderstorms with low-altitude lightning. The modal flash altitude was 10 km, but many flashes occurred at very high altitude (15–20 km). There were also anomalous and stratiform flashes near 5–7 km in altitude. Most flashes were small (,50 km2 area). Comparisons with GLM on 14 and 20 December 2018 indicated that GLM most successfully detected larger flashes (i.e., more than 100 VHF sources), with detection efficiency (DE) up to 90%. However, GLM DE was reduced for flashes that were smaller or that occurred lower in the cloud (e.g., near 6-km altitude). GLM DE also was reduced during a period of OT electrical discharges. Overall, GLM DE was a strong function of thunderstorm evolution and the dominant characteristics of the lightning it produced. © 2020 American Meteorological Society."
"56447276100;57193091858;57211636621;57214202915;56733854600;8075033200;7404865816;57212509672;57212515851;57202204544;57211149101;57212504204;8839875600;7409080503;","Significantly Enhanced Aerosol CCN Activity and Number Concentrations by Nucleation-Initiated Haze Events: A Case Study in Urban Beijing",2019,"10.1029/2019JD031457","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076877143&doi=10.1029%2f2019JD031457&partnerID=40&md5=4b5a71d89ac62fe370c99ad69acd1507","The evolution of haze, involving multiple processes such as nucleation, coagulation, and condensation, may exert complex effects on aerosols' cloud condensation nuclei (CCN) activity and number concentration (NCCN). Based on field campaigns carried out in the winters of 2014 and 2016 in Beijing, we show that NCCN was significantly enhanced by the evolution of haze, substantially driven by the nucleation process (or new particle formation). The enhancement factor of NCCN by such nucleation-initiated haze episodes, E_NCCN, defined as the ratio of NCCN after haze events to NCCN prior to haze events, ranged from 2.2 to 6.5 at a supersaturation (S) = 0.76% and from 4.2 to 17.3 at S = 0.23%, the magnitude of which partially depends on the severity of the haze event. The enhancements are much greater than those previously observed and those from model simulations of contribution from new particle formation. This suggests that CCN sources from new particle formation may be underestimated, needing reevaluation in polluted environments where the subsequent growth of newly formed particles can last 2–3 days, yielding more CCN-sized particles. We further quantified that the changes in particle size and composition during the nucleation-initiated evolution of haze are responsible for &gt; 80% and 12–20%, respectively, of the enhancement in CCN activity. The changes in particle composition had a limited impact because most of the ambient particles were already hydrophilic, with hygroscopic parameters of 0.2–0.65. ©2019. American Geophysical Union. All Rights Reserved."
"57190986692;55892478400;22233326100;57006227400;57196192214;","Effect of satellite temporal resolution on long-term suspended particulate matter in inland lakes",2019,"10.3390/rs11232785","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076567779&doi=10.3390%2frs11232785&partnerID=40&md5=8047684053b3080ca379dafb99f9d1d2","The temporal resolution of satellite determines how well remote sensing products represent changes in the lake environments and influences the practical applications by end-users. Here, a resampling method was used to reproduce the suspended particulate matter (SPM) dataset in 43 large lakes (&gt;50 km2) on the eastern China plain during 2003-2017 at different temporal resolutions using MODIS Aqua (MODISA) based on Google Earth Engine platform, then to address the impact of temporal resolution on the long-term SPM dataset. Differences between the MODISA-derived and reproduced SPM dataset at longer temporal resolution were higher in the areas with large water dynamics. The spatial and temporal distributions of the differences were driven by unfavorable observation environments during satellite overpasses such as high cloud cover, and rapid changes in water quality, such as water inundation, algae blooms, and macrophytes. Furthermore, the annual mean difference in SPM ranged from 5-10% when the temporal difference was less than 10 d, and the differences in summer and autumn were higher than that of other seasons and surpassed 20% when the temporal resolution was more than 16 d. To assure that difference were less than 10% for long-term satellite-derived SPM datasets, the minimal requirement of temporal resolution should be within 5 d for most of the inland lakes and 3 d for lakes with large changes in water quality. This research can be used to not only evaluate the reliability of historically remote sensing products but also provide a reference for planning field campaigns and applying of high spatial resolution satellite missions to monitor aquatic systems in the future. © 2019 by the authors."
"57193176119;57208121852;7103016965;57210069286;","Effects of aerosol in simulations of realistic shallow cumulus cloud fields in a large domain",2019,"10.5194/acp-19-13507-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074554638&doi=10.5194%2facp-19-13507-2019&partnerID=40&md5=8564a9776ca4759a69aab09743cb6175","Previous study of shallow convection has generally suffered from having to balance domain size with resolution, resulting in high-resolution studies which do not capture large-scale behaviour of the cloud fields. In this work we hope to go some way towards addressing this by carrying out cloud-resolving simulations on large domains. Simulations of trade wind cumulus are carried out using the Met Office Unified Model (UM), based on a case study from the Rain In Cumulus over the Ocean (RICO) field campaign. The UM is run with a nested domain of 500&thinsp;km with 500&thinsp;m resolution, in order to capture the large-scale behaviour of the cloud field, and with a double-moment interactive microphysics scheme. Simulations are run using baseline aerosol profiles based on observations from RICO, which are then perturbed. We find that the aerosol perturbations result in changes to the convective behaviour of the cloud field, with higher aerosol leading to an increase (decrease) in the number of deeper (shallower) clouds. However, despite this deepening, there is little increase in the frequency of higher rain rates. This is in contrast to the findings of previous work making use of idealised simulation setups. In further contrast, we find that increasing aerosol results in a persistent increase in domain mean liquid water path and decrease in precipitation, with little impact on cloud fraction. © 2019 BMJ Publishing Group. All rights reserved."
"36243762400;57209469105;55234747900;19337612500;","Development and validation of a supervised machine learning radar Doppler spectra peak-finding algorithm",2019,"10.5194/amt-12-4591-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071753493&doi=10.5194%2famt-12-4591-2019&partnerID=40&md5=d3441d7b1ef09d9020043aa9f338a1fd","In many types of clouds, multiple hydrometeor populations can be present at the same time and height. Studying the evolution of these different hydrometeors in a time-height perspective can give valuable information on cloud particle composition and microphysical growth processes. However, as a prerequisite, the number of different hydrometeor types in a certain cloud volume needs to be quantified. This can be accomplished using cloud radar Doppler velocity spectra from profiling cloud radars if the different hydrometeor types have sufficiently different terminal fall velocities to produce individual Doppler spectrum peaks. Here we present a newly developed supervised machine learning radar Doppler spectra peak-finding algorithm (named PEAKO). In this approach, three adjustable parameters (spectrum smoothing span, prominence threshold, and minimum peak width at half-height) are varied to obtain the set of parameters which yields the best agreement of user-classified and machine-marked peaks. The algorithm was developed for Ka-band ARM zenith-pointing radar (KAZR) observations obtained in thick snowfall systems during the Atmospheric Radiation Measurement Program (ARM) mobile facility AMF2 deployment at Hyytiälä, Finland, during the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign. The performance of PEAKO is evaluated by comparing its results to existing Doppler peak-finding algorithms. The new algorithm consistently identifies Doppler spectra peaks and outperforms other algorithms by reducing noise and increasing temporal and height consistency in detected features. In the future, the PEAKO algorithm will be adapted to other cloud radars and other types of clouds consisting of multiple hydrometeors in the same cloud volume. © 2019 Copernicus GmbH. All rights reserved."
"6508134892;57210855259;55585961800;57193001233;55632057500;","Rigorous Error Modeling for sUAS Acquired Image-Derived Point Clouds",2019,"10.1109/TGRS.2019.2905045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069755402&doi=10.1109%2fTGRS.2019.2905045&partnerID=40&md5=ab179dbe53eead865ce3cd33f12c06d3","The use of small unmanned aircraft systems to collect 3-D topographic data for a variety of geophysical applications has exploded in the last decade. These data are often produced from imagery using structure-from-motion (SfM) algorithms with or without ground control. While the accuracy of these data products has been assessed in a number of efforts, comparatively little focus has been placed on estimating spatially varying ground-space uncertainties in final data products using rigorous error propagation methodology and uncertainty estimation. Uncertainty estimates of the final 3-D products would provide users a more complete understanding of the quality of the products and therefore the applicability of the product. This paper illustrates an end-to-end workflow, using direct geopositioning and SfM techniques to create 3-D topographic point clouds with rigorously propagated accuracy estimates. Included is a method to quantify uncertainty in dense matching and incorporate those contributions into the final ground covariance. The uncertainty estimates are captured as metadata in the point cloud file using standard formats for exploitation. These estimates are critical to the downstream analysis, exploitation, and fusion of data sets; especially in scenarios where ground truth is not an option. The testing of this end-to-end process is described; data from a field campaign were processed without using mensurated control, and the resultant point clouds were compared to surveyed points to evaluate the predicted accuracy. Predicted accuracies bounded observed errors in the horizontal and vertical components. Future enhancements are also proposed. © 1980-2012 IEEE."
"56398306500;56605006500;56734075600;35748657000;56514162100;7410177774;23989889000;6701753599;","Effects of Phase State and Phase Separation on Dimethylamine Uptake of Ammonium Sulfate and Ammonium Sulfate-Sucrose Mixed Particles",2019,"10.1021/acsearthspacechem.9b00142","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069696932&doi=10.1021%2facsearthspacechem.9b00142&partnerID=40&md5=48046ff4b8cd39e02c5ffb21c9335905","Unexpectedly high amounts of aminium salts have been detected in ambient aerosol particles, prompting investigations into their role in new particle formation and nanoparticle growth. Amine uptake and particle-phase processes, including the effects of phase state and non-ideal mixing, are poorly understood. In this study, we conducted kinetic multi-layer modeling of dimethylamine (DMA) uptake by crystalline and aqueous ammonium sulfate (AS) and mixed ammonium sulfate-sucrose particles based on measurements at different relative humidity (RH) values. The temporal evolution of particle mass increases and the humidity dependence were successfully reproduced by considering the amine/ammonium exchange reaction and formation of hygroscopic dimethylaminium sulfate. Thermodynamic equilibrium predictions suggest that aqueous sucrose and AS mixtures undergo phase separation at RH &lt; 94%. The kinetic model simulations reveal that DMA uptake is limited by diffusion of DMA and AS through a viscous sucrose-rich shell at lower RH, resulting in strong concentration gradients in the particle bulk. The model predicts that the true uptake coefficients would range from 2.0 × 10-5 to 2.6 × 10-3 for initially solid particles at low RH, while they can be as high as 0.70-0.82 in aqueous particles at high RH. Uptake coefficients increase when RH and associated particle water content increase, while they generally decrease when the molar fraction of sucrose increases at a specific value of RH. Using new measurements of ambient amines from the Holistic Interactions of Shallow Clouds, Aerosols and Land Ecosystems (HI-SCALE) field campaign as a reference, the model is extrapolated to particles with a diameter of 30 nm and amine mixing ratios in the ppt range to emulate atmospheric conditions. At 70% RH or higher with particles in the liquid phase, amine uptake can lead to a mass increase of approximately 20-60%. Copyright © 2019 American Chemical Society."
"57191329693;7401796996;8629713500;7406215388;56457152000;","Estimation of liquid water path below the melting layer in stratiform precipitation systems using radar measurements during MC3E",2019,"10.5194/amt-12-3743-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068796251&doi=10.5194%2famt-12-3743-2019&partnerID=40&md5=8798736c8c150de2125288f6cfed2747","In this study, the liquid water path (LWP) below the melting layer in stratiform precipitation systems is retrieved, which is a combination of rain liquid water path (RLWP) and cloud liquid water path (CLWP). The retrieval algorithm uses measurements from the vertically pointing radars (VPRs) at 35 and 3 GHz operated by the US Department of Energy Atmospheric Radiation Measurement (ARM) and National Oceanic and Atmospheric Administration (NOAA) during the field campaign Midlatitude Continental Convective Clouds Experiment (MC3E). The measured radar reflectivity and mean Doppler velocity from both VPRs and spectrum width from the 35 GHz radar are utilized. With the aid of the cloud base detected by a ceilometer, the LWP in the liquid layer is retrieved under two different situations: (I) no cloud exists below the melting base, and (II) cloud exists below the melting base. In (I), LWP is primarily contributed from raindrops only, i.e., RLWP, which is estimated by analyzing the Doppler velocity differences between two VPRs. In (II), cloud particles and raindrops coexist below the melting base. The CLWP is estimated using a modified attenuation-based algorithm. Two stratiform precipitation cases (20 and 11 May 2011) during MC3E are illustrated for two situations, respectively. With a total of 13 h of samples during MC3E, statistical results show that the occurrence of cloud particles below the melting base is low (9 %); however, the mean CLWP value can be up to 0.56 kgm-2, which is much larger than the RLWP (0.10 kgm-2). When only raindrops exist below the melting base, the average RLWP value is larger (0.32 kgm-2) than the with-cloud situation. The overall mean LWP below the melting base is 0.34 kgm-2 for stratiform systems during MC3E. © Author(s) 2019."
"57189712592;55607020000;56611366900;","Exploring aerosol-cloud interaction using VOCALS-REx aircraft measurements",2019,"10.5194/acp-19-7955-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067427009&doi=10.5194%2facp-19-7955-2019&partnerID=40&md5=9c525ba987f1c3a4f9d87482eb5620af","In situ aircraft measurements obtained during the VAMOS (Variability of the American Monsoons) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) field campaign are analyzed to study the aerosol-cloud interactions in the stratocumulus clouds over the southeastern Pacific Ocean (SEP), with a focus on three understudied topics (separation of aerosol effects from dynamic effects, dispersion effects, and turbulent entrainmentmixing processes). Our analysis suggests that an increase in aerosol concentration tends to simultaneously increase both cloud droplet number concentration (Nd) and relative dispersion (ω), while an increase in vertical velocity (w) often increases Nd but decreases ω. After constraining the differences of cloud dynamics, the positive correlation between ω and Nd becomes stronger, implying that perturbations of w could weaken the aerosol influence on ω and hence result in an underestimation of dispersion effect. A comparative analysis of the difference of cloud microphysical properties between the entrainment and non-entrainment zones suggests that the entrainment-mixing mechanism is predominantly extremely inhomogeneous in the stratocumulus that capped by a sharp inversion, whereby the variation in liquid water content (25 %) is similar to that of Nd (29 %) and the droplet size remains approximately constant. In entrainment zone, drier air entrained from the top induces fewer cloud droplets with respect to total in-cloud particles (0:56 ± 0:22) than the case in the non-entrainment zone (0:73 ± 0:13) by promoting cloud droplet evaporation. This study is helpful in reducing uncertainties in dispersion effects and entrainment mixing for stratocumulus, and the results of this study may benefit cloud parameterizations in global climate models to more accurately assess aerosol indirect effects. © 2019 The Author(s)."
"56418501800;7003667860;","Evaluating simulated microphysics during olympex using gpm satellite observations",2019,"10.1175/JAS-D-18-0271.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073317695&doi=10.1175%2fJAS-D-18-0271.1&partnerID=40&md5=150f3946d522da448a8034e1413b7674","This study evaluates moist physics in the Weather Research and Forecasting (WRF) Model using observations collected during the Olympic Mountains Experiment (OLYMPEX) field campaign by the Global Precipitation Measurement (GPM) satellite, including data from the GPM Microwave Imager (GMI) and Dual-Frequency Precipitation Radar (DPR) instruments. Even though WRF using Thompson et al. microphysics was able to realistically simulate water vapor concentrations approaching the barrier, there was underprediction of cloud water content and rain rates offshore and over western slopes of terrain. We showed that underprediction of rain rate occurred when cloud water was underpredicted, establishing a connection between cloud water and rain-rate deficits. Evaluations of vertical hydrometeor mixing ratio profiles indicated that WRF produced too little cloud water and rainwater content, particularly below 2.5 km, with excessive snow above this altitude. Simulated mixing ratio profiles were less influenced by coastal proximity or midlatitude storm sector than were GMI profiles. Evaluations of different synoptic storm sectors suggested that postfrontal storm sectors were simulated most realistically, while warm sectors had the largest errors. DPR observations confirm the underprediction of rain rates noted by GMI, with no dependence on whether rain occurs over land or water. Finally, WRF underpredicted radar reflectivity below 2 km and overpredicted above 2 km, consistent with GMI vertical mixing ratio profiles. © 2019 American Meteorological Society."
"57210314074;7005461477;56045802300;","Lightning Location, NOx Production, and Transport by Anomalous and Normal Polarity Thunderstorms",2019,"10.1029/2018JD029979","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070314501&doi=10.1029%2f2018JD029979&partnerID=40&md5=0af80ba0e3188a111a1cba5d6271333e","Production and transport of NOx by convection is critical as it serves as a precursor to tropospheric ozone, an important greenhouse gas. Lightning serves as the largest source of nitrogen oxides (NOx = NO + NO2) to the upper troposphere (UT) and is one of the largest natural sources of NOx. Interest is placed on the vertical advection of NOx because its lifetime increases to several days in the UT compared to roughly 3 hr in the lower troposphere and boundary layer. Thus, lightning can play an important role in ozone production within the UT. However, the amount of NOx produced per flash and NOx advection in storms remain uncertain. This study investigates lightning NOx (LNOx) production and transport processes in anomalous (midlevel positive charge) and normal polarity (midlevel negative charge) thunderstorms by advecting parcels containing LNOx from the flash channels of over 5,600 lightning flashes observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. Results reveal that most flash channels occur near 6-8 km in the normal polarity thunderstorms and 5-6 km within anomalous polarity thunderstorms. Larger flash rates and stronger updrafts in anomalous storms result in considerably larger LNOx mixing ratios (peaks of 0.75-1.75 ppb) in the UT compared to normal polarity storms (peaks &lt; 0.5 ppb). A slightly lower mean flash LNOx production was also found among all five storms in this study (storm mean values of 72-158 moles per flash) compared to previous estimates, which generally parameterize LNOx by flash rate rather than flash count. ©2019. American Geophysical Union. All Rights Reserved."
"57204899091;13403622000;","A Study of Enhanced Heterogeneous Ice Nucleation in Simulated Deep Convective Clouds Observed During DC3",2018,"10.1029/2018JD028889","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057758717&doi=10.1029%2f2018JD028889&partnerID=40&md5=0dd2a3c688944493ffe52b7d427b1e07","The impacts of enhanced heterogeneous ice nucleation (HET) on the properties of deep convective clouds (DCCs) have been investigated in cloud-resolving simulations with the WRF-CHEM model. The study focuses on a case observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. For the simulated DCCs, which had cold cloud-base temperatures, an inverse relationship exists between ice crystal mass produced through HET and anvil ice crystal number concentrations. This seems to be due to the indirect competition between HET and subsequent homogeneous freezing (HOM) for liquid droplets. Furthermore, our simulations suggest that HET enhancements at warmer temperatures are more efficient in depleting liquid droplets below and hence have larger impacts on anvil properties than HET enhancements at colder temperatures do. This temperature dependence indicates that similar increases in the number of ice nucleating particles (INPs) may potentially have different impacts on DCCs, depending on the INP type and at which temperatures they can nucleate ice crystals. We also found that the reduced anvil ice number concentrations due to the enhanced HET may lead to optically thinner anvil clouds. The reduction in cloud optical depth comes from a decrease in ice crystal mass concentrations, and in some runs also from an increase in ice crystal sizes. These results suggest potentially large impacts of INPs on the properties of DCCs, especially if precipitation is predominantly produced through ice processes in the DCCs. The results underscore the importance of fully understanding the temperature-dependent ability of aerosol particles to nucleate ice crystals. ©2018. American Geophysical Union. All Rights Reserved."
"15822963700;25227465100;57198129543;57199315807;56041136700;7102258993;","Sensitivity of airborne radio occultation to tropospheric properties over ocean and land",2018,"10.5194/amt-11-763-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041843523&doi=10.5194%2famt-11-763-2018&partnerID=40&md5=70f2b46e183cb49d788f1f9e48253889","Airborne radio occultation (ARO) measurements collected during a ferry flight at the end of the PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT) field campaign from the Virgin Islands to Colorado are analyzed. The large contrast in atmospheric conditions along the flight path from the warm and moist Caribbean Sea to the much drier and cooler continental conditions provides a unique opportunity to address the sensitivity of ARO measurements to the tropospheric temperature and moisture changes. This long flight at nearly constant altitude ( 1/413km) provided an optimal configuration for simultaneous high-quality ARO measurements from two high-gain side-looking antennas, as well as one relatively lower gain zenith (top) antenna. The omnidirectional top antenna has the advantage of tracking robustly more occulting satellites in all direction as compared to the limited-azimuth tracking of the side-looking antennas. Two well-adapted radio-holographic bending angle retrieval methods, full-spectrum inversion (FSI) and phase matching (PM), were compared with the standard geometric-optics (GO) retrieval method. Comparison of the ARO retrievals from the top antenna with the near-coincident ECMWF reanalysis-interim (ERA-I) profiles shows only a small root-mean-square (RMS) refractivity difference of 1/40.3% in the drier upper troposphere from 1/45 to 1/411.5km over both land and ocean. Both the FSI and PM methods improve the ARO retrievals in the moist lower troposphere and reduce the negative bias found in the GO retrieval due to atmospheric multipath. In the lowest layer of the troposphere, the ARO refractivity derived using FSI shows a negative bias of about 2%. The increase of the refractivity bias occurs below 5km over the ocean and below 3.5km over land, corresponding to the approximate altitude of large vertical moisture gradients above the ocean and land surface, respectively. In comparisons to radiosondes, the FSI ARO soundings capture well the height of layers with sharp refractivity gradients but display a negative refractivity bias inside the boundary layer. The unique opportunity to make simultaneous independent recordings of occultation events from multiple antennas establishes that high-precision ARO measurements can be achieved corresponding to an RMS difference better than 0.2% in refractivity (or 1/40.4K). The surprisingly good quality of recordings from a very simple zenith antenna increases the feasibility of developing an operational tropospheric sounding system onboard commercial aircraft in the future, which could provide a large number of data for direct assimilation in numerical weather prediction models. © Author(s) 2018."
"8093846300;57204112140;36770262000;38461378900;7102609908;24399716000;7103201242;","Videosonde-observed graupel in different rain systems during Pre-YMC Project",2018,"10.2151/SOLA.2018-026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063137730&doi=10.2151%2fSOLA.2018-026&partnerID=40&md5=1f507be25fdd9371c97221c3ba127178","Videosonde observations were conducted at the southwestern coastal region of Sumatra Island, Indonesia, as part of a pilot field campaign of the Years of the Maritime Continent project (Pre- YMC), to investigate the role of solid hydrometeor for precipitation processes in clouds. Videosondes were launched into three types of clouds: convective and stratiform clouds, and a thick upper stratiform cloud with shallow convection at lower level. A quantitative evaluation of the graupel shape data obtained from the videosondes showed different graupel formations in different rain systems. For the typical stratiform cloud, almost no graupel was observed. In contrasts, for the thick upper stratiform clouds with shallow convection, large numbers of ice crystals in the upper layer suggested to act as embryos and form a lot of graupel with the riming of the supercooled droplets that was supposed to be provided from the shallow convection. On the other hand, for the convection case, the videosonde observed spherical graupel just above the freezing level. This suggested that frozen drops acting as embryos formed spherical graupel, which were uplifted by the strong updraft in the convective cloud, and were different from the generally irregular-shaped graupel in the thick upper stratiform cloud. © The Author(s) 2018."
"6602574642;7102515899;7201815022;55474246200;6603462157;7003382045;","Supporting NASA SnowEx remote sensing strategies and requirements for L-band interferometric snow depth and snow water equivalent estimation",2017,"10.1109/IGARSS.2017.8127224","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041835458&doi=10.1109%2fIGARSS.2017.8127224&partnerID=40&md5=e8ae3c0793365c1b36cad96c2879fb85","The objectives of this research are to (1) address remote sensing strategies and requirements for estimating snow depth and snow water equivalent (SWE) using existing L-Band interferometric data sets in coordination with field-based observations and modeling frameworks and, with this information, (2) inform the Next Generation Cold Land Processes Experiment (SnowEx) toward articulating the appropriate science and research questions for a single motivating science plan. As proposed, SnowEx is a multi-year airborne snow campaign with a primary goal of exploring multimodal sensor observations in coordination with field campaigns to inform the next generation snow remote sensing satellite platform. Based on limitations of satellite-based optical and LiDAR instruments operating in regions of the globe with consistent cloud-cover, the fact that many snow-dominated regions are at more northerly latitudes (limited solar illumination in the middle of winter), and these snow-dominated regions often experience periods of prolonged cloud cover (due to synoptic precipitation events), a microwave remote sensing platform may be the most viable path to space for a dedicated snow remote sensing mission. Specifically, L-Band radar interferometry has shown some unique promise with an archive of historical and contemporary satellite collections from JAXA's PALSAR-1 and PALSAR-2 instruments, respectively. Moreover, with the expected NISAR (NASA-ISRO Synthetic Aperture Radar) mission launch in 2020 and the unprecedented availability of dedicated global interferometric L-Band products every 12-days, as well as what is in essence a NISAR airborne simulator in JPL's UAVSAR platform, the L-Band interferometric approach to estimating snow depth and snow water equivalent (SWE) requires further investigation within the context of in-situ observations and modeling frameworks. © 2017 IEEE."
"55683079000;7005461477;35325977100;13405658600;","Interactions between the MJO, Aerosols, and Convection over the Central Indian Ocean",2017,"10.1175/JAS-D-16-0054.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011633135&doi=10.1175%2fJAS-D-16-0054.1&partnerID=40&md5=fd0b56578068a3815d766f04964bb774","This study examines covariability of boundary layer cloud condensation nuclei (CCN) concentrations [estimated using the GEOS 3D chemical transport model (GEOS-Chem)], convective clouds, precipitation, and lightning observed over the central equatorial Indian Ocean (CIO). Three distinct Madden-Julian oscillation (MJO) episodes were observed during the recent Dynamics of the MJO (DYNAMO; 2011/12) field campaign. Coherent relationships between CCN, rainfall, and lightning are apparent in time series from DYNAMO and more lightning located north of the equator is noted, compared to south of the equator. More-polluted environments north of the equator contained deep convective clouds that had stronger radar reflectivities (~2-3 dB) in the mixed-phase region (5-10-km altitude) compared to south of the equator. Following discussion of the MJO episodes that occurred during DYNAMO, 22 cycles of the MJO observed during boreal cold seasons in the years 2004-11 are examined with the aid of TRMM satellite observations. Climatological results suggest that horizontal transport of continental aerosols from proximal landmasses by the large-scale circulation after active MJO convection reinforces the meridional gradient of CCN concentrations in the CIO. Satellite observations depicted comparable aggregate cold cloud feature area in both regions in similar thermodynamic environments, leading to the suggestion that higher CCN concentrations north of the equator act to invigorate convection. Direct comparisons of convective intensity metrics to CCN support the aerosol hypothesis; however, in line with previous studies, it is acknowledged that conditional instability, vertical wind shear, and environmental moisture can modulate the initial development of deep convection over the CIO during select phases of the MJO. © 2017 American Meteorological Society."
"7005659847;57140160700;7102790108;35568326100;57205842560;7003351429;7006577245;7004607037;7003469326;7005899926;37099534700;57191473265;55192470800;7004177770;57148462400;14066601400;55951906300;7102113229;7101973570;40661065000;6602109913;8387523500;8562497500;7004307916;55053339600;57206604773;36664097800;","Contribution of EARLINET/ACTRIS to the summer 2013 Special Observing Period of the ChArMEx project: monitoring of a Saharan dust event over the western and central Mediterranean",2016,"10.1080/01431161.2016.1222102","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990855929&doi=10.1080%2f01431161.2016.1222102&partnerID=40&md5=e28dd49c10794cafa6f90571f3229536","In the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr/) initiative, a field campaign took place in the western Mediterranean Basin between 10 June and 5 July 2013 within the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project. The scientific objectives of ADRIMED are the characterization of the most common ‘Mediterranean aerosols’ and their direct radiative forcing (column closure and regional scale). During 15–24 June a multi-intrusion dust event took place over the western and central Mediterranean Basin. Extra measurements were carried out by some EARLINET/ACTRIS (European Aerosol Research Lidar Network /Aerosols, Clouds, and Trace gases Research InfraStructure Network, http://www.actris.net/) lidar stations in Spain and Italy, in particular on 22 June in support to the flight over southern Italy of the Falcon 20 aircraft involved in the campaign. This article describes the physical and optical properties of dust observed at the different lidar stations in terms of dust plume centre of mass, optical depth, lidar ratio, and particle depolarization ratio. To link the differences found in the origin of dust plumes, the results are discussed on the basis of back-trajectories and air- and space-borne lidars. This work puts forward the collaboration between a European research infrastructure (ACTRIS) and an international project (ChArMEx) on topics of interest for both parties, and more generally for the atmospheric community. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"36059595100;15751598400;7006303509;7102654014;29167462600;57155431600;7004242319;","Evaluation of long-term surface-retrieved cloud droplet number concentration with in situ aircraft observations",2016,"10.1002/2015JD024082","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959932952&doi=10.1002%2f2015JD024082&partnerID=40&md5=179cf4b6fe6ef5d02b0108a81f8610be","A new operational retrieval of cloud droplet number concentration (ND) at cloud base has been produced from surface remote sensors at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site for 13 years from January 1998 to January 2011. The retrieval is based on surface radiometer measurements of cloud optical depth from the multifilter rotating shadow band radiometer and liquid water path from the microwave radiometer (MWR). It is only applicable for single-layered overcast warm (stratus or stratocumulus) clouds. Evaluation with in situ aircraft measurements during the extended-term aircraft field campaign, Routine ARM Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO), shows that the retrieved ND robustly reproduces the primary mode of the in situ measured probability density function (PDF) but produces too wide a distribution, primarily caused by frequent high cloud droplet number concentration. Our analysis shows that the error in the MWR retrievals at low liquid water paths is one possible reason for this deficiency. Modification through the diagnosed liquid water path from the coordinate solution improves not only the PDF of the retrieved ND but also the relationship between the cloud droplet number concentration and cloud droplet effective radius. Consideration of entrainment effects rather than assuming an adiabatic cloud improves the values of the ND retrieval by reducing the magnitude of cloud droplet number concentration. Aircraft measurements and retrieval comparisons suggest that retrieving the vertical distribution of cloud droplet number concentration and effective radius is feasible with an improvement of the parameter representing the mixing effects between environment and clouds and with a better understanding of the effect of mixing degree on cloud properties. ©2016. American Geophysical Union. All Rights Reserved."
"55801689800;26023688200;56737226500;55967153600;","Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations",2015,"10.5194/acpd-15-22637-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969509677&doi=10.5194%2facpd-15-22637-2015&partnerID=40&md5=12b857392ed241189ea077da4820d56b","Large eddy simulations (LES) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Due to the presence of a topographically structured island surface in the domain center, the model setup has to be designed with open lateral boundaries. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude perturbations. In this work, this method is for the first time tested and validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE field campaign is used for both model initialization and a comparison with Doppler wind lidar data. Several numerical sensitivity tests are carried out to demonstrate the problems related to ""gray zone modeling"" when using coarser spatial grid spacings beyond the inertial subrange of three-dimensional turbulence or when the turbulent marine boundary layer flow is replaced by laminar winds. Especially cloud properties in the downwind area west of Barbados are markedly affected in these kinds of simulations. Results of an additional simulation with a strong trade-wind inversion reveal its effect on cloud layer depth and location. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ≈ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with wind lidar data show similarities in the formation of the daytime convective plume and the mean vertical wind structure. © Author(s) 2015."
"36803253000;35887706900;20435752700;6603591733;","On the properties and radiative effects of small convective clouds during the eastern Mediterranean summer",2015,"10.1088/1748-9326/10/4/044006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928719652&doi=10.1088%2f1748-9326%2f10%2f4%2f044006&partnerID=40&md5=6748961f725b2d30585e7604cf033c35","A ground-based field campaign was conducted over the summer of 2011 in Israel to measure the properties of small warm clouds. The horizontal size distribution for cloud sizes of 50-3000 m is presented, with a special focus on the properties of the smallest clouds (liquid water path <10 g m-2, cloud thickness <∼50 m) and their estimated radiative effect. We show that these small clouds dominate the cloud radiative properties during the summer over the studied region. The average daily cloud cover of the small cloud subset throughout the field campaign was 81 ± 21% (corresponding to 30 ± 14.3% of the total measured time), and they contributed 83 ± 19.4% of the clouds' reflectance. Their average daily radiative effect was estimated at -3.6 ± 2.1 W m-2. © 2015 IOP Publishing Ltd."
"14019342100;56900961300;6701718885;57196115458;54420868300;6701858531;","On the variability of Wilson currents by storm type and phase",2014,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086812691&partnerID=40&md5=e73f5d63e0e93b10f0c708f73aec946d","Storm total conduction currents from electrified clouds are thought to play a major role in maintaining the potential difference between the earth's surface and the upper atmosphere within the Global Electric Circuit (GEC). However, it is not entirely known how the contributions of these currents vary by cloud type and phase of the clouds life cycle. Estimates of storm total conduction currents were obtained from data collected over two decades during multiple field campaigns involving the NASA ER-2 aircraft. In this study the variability of these currents by cloud type and lifecycle is investigated. We also compared radar derived microphysical storm properties with total storm currents to investigate whether these storm properties can be used to describe the current variability of different electrified clouds. The ultimate goal is to help improve modeling of the GEC via quantification and improved parameterization of the conduction current contribution of different cloud types. © International Conference on Atmospheric Electricity, ICAE 2014"
"37052838900;56444367400;8973773500;56006428600;55253708400;6603451431;","Mobile mapping and the use of backscatter data for the modelling of intertidal zones of beaches",2014,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946743546&partnerID=40&md5=c4cbe6839a8eb10573d4f4530ccff4e8","Mobile mapping with laser scanning is frequently limited to the sole geometric reconstruction of objects or surfaces. In the special case of the construction of Digital Elevation Models (DEMs) of intertidal zone of beaches, this task is known to be very challenging. In the context of the interdisciplinary research project named ‘SeArch’, which aims at documenting and managing archaeological patrimony in the North Sea, a field campaign was organized in the summer of 2013. During this campaign, an amphibious vehicle (ARGO) was equipped with a Terrestrial Laser Scanner (TLS) in profiler mode, an Inertial Measurement Unit (IMU), a Real-Time Kinematic Global Navigation Satellite System (RTK GNSS) and a PC hydrographic data acquisition software and huge storage capacity. Based on previous research, this configuration appeared to have the best performance under the environmental conditions at the Belgian North Sea coast. Especially for the intertidal zones of beaches, the use of this mobile platform resulted in very promising results from a geometrical point of view. A summary of the results of the campaign is presented in this paper. Although the focus of this campaign was on the construction of DEMs with a high resolution and a high accuracy, the used Leica HDS 6200 phase-based laser scanner also returned a backscatter value for each measured point. A provisional analysis of these values suggested a relation between the physical properties of the reflecting surface and the registered backscatter values. However, earlier studies have also demonstrated the influence of the incidence angle and measured distance on this backscatter value. As will be discussed in this paper, a correction function can be defined that takes these parameters into account as weights for corrected backscatter data. In combination with the commonly used point cloud, the corrected values allow the calculation of false-color composites of the measured surface and the detection and description of features. © SGEM2014."
"57199914094;35390825100;7006107059;55659925600;6506458269;57136469800;8359591200;","Chemical composition of tropospheric air masses encountered during high altitude flights (11.5 km) during the 2009 fall Operation Ice Bridge field campaign",2012,"10.1029/2012JD017858","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84866714223&doi=10.1029%2f2012JD017858&partnerID=40&md5=6580761f50ca36d0a11e6b70445b803b","[1] As part of the 2009 Operation Ice Bridge campaign, the NASA DC-8 aircraft was used to fill the data-time gap in laser observation of the changes in ice sheets, glaciers and sea ice between ICESat-I (Ice, Cloud, and land Elevation Satellite) and ICESat-II. Complementing the cryospheric instrument payload were four in situ atmospheric sampling instruments integrated onboard to measure trace gas concentrations of CO<inf>2</inf>, CO, N<inf>2</inf>O, CH <inf>4</inf>, water vapor and various VOCs (Volatile Organic Compounds). This paper examines two plumes encountered at high altitude (12 km) during the campaign; one during a southbound transit flight (13°S) and the other at 86°S over Antarctica. The data presented are especially significant as the Southern Hemisphere is heavily under-sampled during the austral spring, with few if any high-resolution airborne observations of atmospheric gases made over Antarctica. Strong enhancements of CO, CH<inf>4</inf>, N<inf>2</inf>O, CHCl <inf>3</inf>, OCS, C<inf>2</inf>H<inf>6</inf>, C<inf>2</inf>H<inf>2</inf> and C<inf>3</inf>H<inf>8</inf> were observed in the two intercepted air masses that exhibited variations in VOC composition suggesting different sources. The transport model FLEXPART showed that the 13°S plume contained predominately biomass burning emissions originating from Southeast Asia and South Africa, while both anthropogenic and biomass burning emissions were observed at 86° S with South America and South Africa as indicated source regions. The data presented here show evidence that boundary layer pollution is transported from lower latitudes toward the upper troposphere above the South Pole, which may not have been observed in the past. © 2012. American Geophysical Union. All Rights Reserved."
"7005433221;","Compact micropulse backscatter lidar: Airborne and ground-based applications",2011,"10.30638/eemj.2011.023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79959505949&doi=10.30638%2feemj.2011.023&partnerID=40&md5=26b9d3a7c5f6e88d7a8d9b329481200f","The article is a review of the activities with one type of extremely compact elastic backscatter lidar. The reported lidar is based on micro-pulse laser operation and photon counting detection. The starting objective for the development was the automatic operation from stratospheric aircraft for sub-visible clouds detection. The developed lidar proved also optimal for ground-based measurements of Atmospheric Boundary Layer (ABL) development and Aerosol Backscatter Coefficient (ABC). As an illustration of its airborne capabilities selected results of thin clouds detection are presented. As examples for its ground-based operation cases of ABL development and ABC measurements are reported. These include also monitoring of the variation of Eyjafjallajokull volcano debris transport above Neu châtel (Switzerland), as well as a statistical study on the correlation between the lidar measurements and visual range. The years of operation proved that such lidars answer the demands for operation at remote sites and at field campaigns."
"20435686100;7006392180;7102610603;","Wavelets transform and Linear Spectral Mixture Model applied to MODIS time series for land cover change analysis",2007,"10.1109/IGARSS.2007.4423209","https://www.scopus.com/inward/record.uri?eid=2-s2.0-82355190833&doi=10.1109%2fIGARSS.2007.4423209&partnerID=40&md5=e1579685278b80ee1cc758468b5756ff","This work presents a methodology that uses fraction images derived from Linear Spectral Mixture Model and wavelets transform from MODIS time-series for land cover change analysis. Our approach uses MODIS/Terra surface reflectance images acquired from 2000 to 2006 time period. For this study, a test site was selected in the Mato Grosso State, Brazilian Amazonia, encompassing several landscape types as tropical forest, savanna, transitional forest, regrowth, deforested areas, croplands and pasture. The samples of land cover classes were collected during four field campaigns (2003, 2004, 2005, and 2006) to be used as ground truth. The linear spectral mixture model was applied to the MODIS surface reflectance images of RED, NIR and MIR spectral bands. This model generated the vegetation, shade, and soil fraction images. In the next step, the Meyer orthogonal Discrete Wavelets Transform was used for filtering the time-series of MODIS fraction images. The filtered signal was reconstructed excluding high frequencies for each pixel in the fraction images (soil, vegetation, and shade) of the time-series. This procedure allows to observe the original signal without clouds and other noises. The accumulated precipitation data were used for dynamic phenological analysis, which showed the temporal lags between wet season and vegetation growing stages. The results show that wavelets transform can provide a gain in multitemporal analysis and visualization on inter-annual fraction images variability patterns. © 2007 IEEE."
"7004055178;57199054070;","Radiative transfer in shallow cumulus cloud fields: Observations and first analysis with the Diram instrument during the BBC-2 field campaign in May 2003",2006,"10.1016/j.atmosres.2005.09.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749343342&doi=10.1016%2fj.atmosres.2005.09.006&partnerID=40&md5=d9176de0395d88e0e3f9bc620012a759","The cloud albedo is a crucial parameter in radiation budget studies, and is one of the main forcings in climate. We have designed and made a device, Diram (directional radiance distribution measurement device), which not only measures reflection and transmission of solar radiation through clouds, but which also determines the radiance distribution. The construction contains 42 sensors, consisting of a collimation system and a detector, which are mounted in two domes (21 in each). The collimators reduce the field of view of each sensor to ∼7°. The domes were mounted on top and below of the Meteo France Merlin IV research aircraft. The 42 signals were continuously logged with a frequency of 10 Hz during a number of flights in the framework of the Baltex Bridge-2 campaign at Cabauw (The Netherlands) in May 2003. The Diram instrument provided radiances during in situ observations of cumulus and (broken) stratocumulus clouds and detected anisotropic effects in solar radiation scattered by clouds which are due to different cloud geometries and which are related to microphysical cloud properties. Microphysical cloud properties were obtained from the Gerber PVM100A optical sensor aboard the aircraft. Liquid water content and particle surface area were logged with a frequency of 200 Hz. Data have been collected from a total of 10 days in different weather conditions (clear sky, broken cumulus, stratocumulus and multilayered cloud). A clear sky test of the Diram indicated that the device was able to reproduce the Rayleigh scattering pattern. During flights in stratocumulus fields, strongly anisotropic patterns were observed. The DIRAM observations confirm that in thin clouds a strong preference for forward scattering is observed in the transmitted radiation field while for thicker clouds the pattern becomes more isotropic, with a slightly brighter centre relative to the limb direction. © 2006 Elsevier B.V. All rights reserved."
"8640358800;7003544485;","An estimate of day-time turbulent diffusivity over complex terrain from standard weather data",2005,"10.1007/s00704-004-0100-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-20444456338&doi=10.1007%2fs00704-004-0100-5&partnerID=40&md5=c2d61b0b473d9d4ddc2eecc3f2c534eb","A method for the calculation of atmospheric turbulent diffusivity over complex terrain during day-time is presented, which may improve the predictions based on diagnostic meteorological models. The proposed procedure takes into account the geographic location of the area (latitude and longitude), the time of the day, the inclination and exposition of the surface, the soil type and the cloud cover. These data are used to compute the amount of solar heat flux contributing to the heating of the air mass above the ground level, and, consequently, the atmospheric turbulence. The model accounts for the effect of shadows generated by mountain profiles, which determine a differential heating at the valley floor and induce spatial and temporal variations of turbulent diffusivity. Model calibration has been performed through ground data collected during a field campaign in the Adige valley in the surrounding of the town of Trento. © Springer-Verlag/Wien 2005."
"6603933557;7006962390;7005421048;","TReSS : A transportable remote sensing station for atmospheric research & satellite validation",2004,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142634832&partnerID=40&md5=65d61a02bbd65fe8907785e33999a24b","The LiMAG team (http://www.lmd.polytechnique.fr/̃Limag) has recently developed a Transportable Remote Sensing Station so called ""TReSS"" for atmospheric application and validation of satellite observations i.e. ICESat in 2004, CALIPSO starting in 2005, ADM-ÆOLUS end of 2007. As it stands TReSS is an active and passive remote sensors payload to be operated from the ground by a limited number of persons. The station has been designed to fit in a rental van to be transported and operated during field campaigns. Each instrument provides valuable information on radiative and geometrical properties but a Lidar-Radiometers synergism is mainly intended to provide a more effective way of retrieving the backscatter and extinction coefficients profiles. During the year 2003 different meteorological situations have been observed, among which: atmospheric boundary layer (ABL) diurnal cycle, free-troposphere aerosols coming from Sahara desert, effects of the heat wave over France in August 2003 on diurnal cycle and aerosol transport, gravity waves, frontal and cirrus clouds. At present, TReSS is currently operated in Palaiseau near Paris to monitor clouds and aerosols in a near rural area."
"6602447198;55967620900;","Atmospheric back radiation in the tropical pacific: Intercomparison of in-situ measurements, simulations and satellite retrievals",1997,"10.1007/BF01027386","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0039978466&doi=10.1007%2fBF01027386&partnerID=40&md5=f3b7e9608ea371deab192869a879406d","The back radiation has been measured with an Eppley pyrgeometer on board the R/V Vickers in the tropical Pacific Ocean during the field campaigns COARE (Coupled Ocean Atmosphere Response Experiment) and CEPEX (Central Equatorial Pacific Experiment) in February and March 1993, respectively. As part of these compaigns radiosondes have been launched from the Vickers several times per day and cloud cover was observed frequently. The radiosonde and cloud observations are used together with a radiative transfer model to calculate the back radiation for a subsequent intercomparison with the pyrgeometer measurements. Another means of comparison is derived from space-borne SSM/I (Special Sensor Microwave/Imager) measurements. The mean difference between pyrgeometer measurements and simulated downwelling irradiance at the sea surface is less than 2 W/m2, at a mean of 425 W/m2 in the warm pool, with a standard deviation of 8 W/m2. The comparison of satellite measurements with pyrgeometer readings shows a mean difference of -3 W/m2 and a standard deviation of 14 W/m2. The mean difference between satellite-derived back radiation and simulated one is 3 W/m2 with a standard deviation of 14 W/m2. Comparisons with results obtained from bulk formulae applied to surface meteorological observations show a good performance of the bulk parameterisations in the cloud-free case but a general overestimation of the back radiation in cloudy situations."
"7006595513;57199809096;7102496779;","A new method to measure the size distribution of insoluble submicron particles in water",1994,"10.1016/0021-8502(94)90085-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028396948&doi=10.1016%2f0021-8502%2894%2990085-X&partnerID=40&md5=8bd15c00d62032924b63ba0327913a78","In the atmosphere, cloud and fog droplets usually contain insoluble material. The role of these insoluble particles is still unknown today, and is of interest to study. To determine the size distribution and number concentration of these particles in water, different techniques are available. The instrumentation, however, to measure nanometer-sized particles down to 50 nm diameter is not known. A new instrument, the Liquid Tandem Differential Mobility Analyser (LTDMA), was developed to measure size distributions of insoluble particles in water in the size range 50-300 nm in diameter. The new method is based on nebulising, e.g. cloud water and forming a residue aerosol consisting of both, insoluble particles with a soluble shell, and pure soluble particles. The insoluble, hydrophobic particles can be separated from soluble, hygroscopic residue particles with a Tandem Differential Mobility Analyser. The system is calibrated with monodisperse latex particles to determine the size-dependent transmission factor of insoluble particles of the Liquid Tandem Differential Mobility Analyser. A size distribution of insoluble particles in cloud water is presented as an application of this new measuring method. The cloud water sample was taken during the field campaign of the EUROTRAC sub project Ground-based Cloud Experiments (GCE) on the Kleiner Feldberg mountain, Germany, in November 1990. © 1994."
"7003900545;57190360792;35607650700;","A comparison of GOES incident solar radiation estimates with a topographic solar radiation model during FIFE",1993,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027833894&partnerID=40&md5=8b612be888b0fefece053f0844021742","In this research we compare insolation estimates from a topographic solar radiation model with those derived from a coarse-resolution satellite algorithm. Half-hourly pyranometer and GOES estimates were obtained for the dates August 10-August 20, 1987 during the third intensive field campaign (IFC-3) of FIFE. Our results show that under clear atmospheric conditions the uncertainty of the GOES algorithm is greater than the error introduced by the gentle terrain of the FIFE site and that under non uniform atmospheric conditions, it is the clouds that dominate the spatial variability. If the modeling situation requires that the topography be considered, the GOES estimates can be used to derive a topographic model to obtain more realistic insolation at subpixel scales. -from Authors"
"57191031593;42961641500;57207823252;7003740015;8404544300;7006204597;57141453800;7003487564;34771961300;7005304841;57214957727;","Influence of Arctic Microlayers and Algal Cultures on Sea Spray Hygroscopicity and the Possible Implications for Mixed-Phase Clouds",2020,"10.1029/2020JD032808","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092303219&doi=10.1029%2f2020JD032808&partnerID=40&md5=c7ff669ba44e4a35e2d8a446416edaef","As Arctic sea ice cover diminishes, sea spray aerosols (SSA) have a larger potential to be emitted into the Arctic atmosphere. Emitted SSA can contain organic material, but how it affects the ability of particles to act as cloud condensation nuclei (CCN) is still not well understood. Here we measure the CCN-derived hygroscopicity of three different types of aerosol particles: (1) Sea salt aerosols made from artificial seawater, (2) aerosol generated from artificial seawater spiked with diatom species cultured in the laboratory, and (3) aerosols made from samples of sea surface microlayer (SML) collected during field campaigns in the North Atlantic and Arctic Ocean. Samples are aerosolized using a sea spray simulation tank (plunging jet) or an atomizer. We show that SSA containing diatom and microlayer exhibit similar CCN activity to inorganic sea salt with a κ value of ∼1.0. Large-eddy simulation (LES) is then used to evaluate the general role of aerosol hygroscopicity in governing mixed-phase low-level cloud properties in the high Arctic. For accumulation mode aerosol, the simulated mixed-phase cloud properties do not depend strongly on κ, unless the values are lower than 0.4. For Aitken mode aerosol, the hygroscopicity is more important; the particles can sustain the cloud if the hygroscopicity is equal to or higher than 0.4, but not otherwise. The experimental and model results combined suggest that the internal mixing of biogenic organic components in SSA does not have a substantial impact on the cloud droplet activation process and the cloud lifetime in Arctic mixed-phase clouds. © 2020. The Authors."
"55622713800;7005035762;57219343910;57219005005;57126848900;","Mid-level clouds are frequent above the southeast Atlantic stratocumulus clouds",2020,"10.5194/acp-20-11025-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092273927&doi=10.5194%2facp-20-11025-2020&partnerID=40&md5=e0109ea36aa6c4a9b0bc67b9f9299952","Shortwave-absorbing aerosols seasonally overlay extensive low-level stratocumulus clouds over the southeast Atlantic. While much attention has focused on the interactions between the low-level clouds and the overlying aerosols, few studies have focused on the mid-level clouds that also occur over the region. The presence of mid-level clouds over the region complicates the space-based remote-sensing retrievals of cloud properties and the evaluation of cloud radiation budgets. Here we characterize the mid-level clouds over the southeast Atlantic using lidar-and radar-based satellite cloud retrievals and observations collected in September 2016 during the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) field campaign. We find that mid-level clouds over the southeast Atlantic are relatively common, with the majority of the clouds occurring between altitudes of 5 and 7 km and at temperatures between 0 and -20 °C. The mid-level clouds occur at the top of a moist mid-tropospheric smoke-aerosol layer, most frequently between August and October, and closer to the southern African coast than farther offshore. They occur more frequently during the night than during the day. Between July and October, approximately 64 % of the mid-level clouds had a geometric cloud thickness less than 1 km, corresponding to a cloud optical depth of less than 4. A lidar-based depolarization-backscatter relationship for September 2016 indicates that the mid-level clouds are liquid-only clouds with no evidence of the existence of ice. In addition, a polarimeter-derived cloud droplet size distribution indicates that approximately 85 % of the September 2016 mid-level clouds had an effective radius less than 7 μm, which could further discourage the ability of the clouds to glaciate. These clouds are mostly associated with synoptically modulated mid-tropospheric moisture outflow that can be linked to the detrainment from the continental-based clouds. Overall, the supercooled mid-level clouds reduce the radiative cooling rates of the underlying low-altitude cloud tops by approximately 10 K d-1, thus influencing the regional cloud radiative budget. © Author(s) 2020."
"57192945050;7006446865;55491523900;","Columnar vertical profile (CVP) methodology for validating polarimetric radar retrievals in ice using in situ aircraft measurements",2020,"10.1175/JTECH-D-20-0011.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084706580&doi=10.1175%2fJTECH-D-20-0011.1&partnerID=40&md5=b8f6d440b221dc36506969d875cd4e3d","A novel way to process polarimetric radar data collected via plan position indicator (PPI) scans and display those data in a time–height format is introduced. The columnar vertical profile (CVP) methodology uses radar data collected via multiple elevation scans, limited to data within a set region in range and azimuth relative to the radar, to create vertical profiles of polarimetric radar data representative of that limited region in space. This technique is compared to others existing in the literature, and various applications are discussed. Polarimetric ice microphysical retrievals are performed on CVPs created within the stratiform rain region of two mesoscale convective systems sampled during two field campaigns, where CVPs follow the track of research aircraft. Aircraft in situ data are collocated to microphysical retrieval data, and the accuracy of these retrievals is tested against other retrieval techniques in the literature. © 2020 American Meteorological Society."
"57212818622;35263384600;7005587298;55911904900;56473250300;57126848900;7201656768;57205143137;6506718750;55545601500;35795663000;","Inversion of multiangular polarimetric measurements from the ACEPOL campaign: An application of improving aerosol property and hyperspectral ocean color retrievals",2020,"10.5194/amt-13-3939-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089119277&doi=10.5194%2famt-13-3939-2020&partnerID=40&md5=8597a0c5afc92fcd3785d15df461e3f7","NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, scheduled for launch in the time frame of late 2022 to early 2023, will carry the Ocean Color Instrument (OCI), a hyperspectral scanning radiometer, and two multiangle polarimeters (MAPs), the UMBC Hyper-Angular Rainbow Polarimeter 2 (HARP2) and the SRON Spectro- Polarimeter for Planetary EXploration one (SPEXone). One purpose of the PACE MAPs is to better characterize aerosol properties, which can then be used to improve atmospheric correction for the retrieval of ocean color in coastal waters. Though this is theoretically promising, the use of MAP data in the atmospheric correction of colocated hyperspectral ocean color measurements have not yet been well demonstrated. In this work, we performed aerosol retrievals using the MAP measurements from the Research Scanning Polarimeter (RSP) and demonstrate its application to the atmospheric correction of hyperspectral radiometric measurements from SPEX airborne. Both measurements were collected on the same aircraft from the Aerosol Characterization from Polarimeter and Lidar (ACEPOL) field campaign in 2017. Two cases over ocean with small aerosol loading (aerosol optical depth 0:04) are identified including colocated RSP and SPEX airborne measurements and Aerosol Robotic Network (AERONET) ground-based observations. The aerosol retrievals are performed and compared with two options: one uses reflectance measurement only and the other uses both reflectance and polarization. It is demonstrated that polarization information helps reduce the uncertainties of aerosol microphysical and optical properties. The retrieved aerosol properties are then used to compute the contribution of atmosphere and ocean surface for atmospheric correction over the discrete bands from RSP measurements and the hyperspectral SPEX airborne measurements. The waterleaving signals determined this way are compared with both AERONET and Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color products for performance analysis. The results and lessons learned from this work will provide a basis to fully exploit the information from the unique combination of sensors on PACE for aerosol characterization and ocean ecosystem research. © 2020 Copernicus GmbH. All rights reserved."
"56548875900;56993642000;57189498750;55324559500;55747201700;57218243091;6602810042;57218243855;57200314218;57190068004;25647920200;26422803600;7003510880;56032594900;","The vertical variability of black carbon observed in the atmospheric boundary layer during DACCIWA",2020,"10.5194/acp-20-7911-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088418990&doi=10.5194%2facp-20-7911-2020&partnerID=40&md5=b085f388447b2c4dc0caa32d2699b9a0","This study underlines the important role of the transported black carbon (BC) mass concentration in the West African monsoon (WAM) area. BC was measured with a micro-aethalometer integrated in the payload bay of the unmanned research aircraft ALADINA (Application of Light-weight Aircraft for Detecting IN situ Aerosol). As part of the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) project, 53 measurement flights were carried out at Savè, Benin, on 2-16 July 2016. A high variability of BC (1.79 to <span classCombining double low line""inline-formula"">2.42±0.31</span> <span classCombining double low line""inline-formula"">μ</span>g m<span classCombining double low line""inline-formula"">-3</span>) was calculated along 155 vertical profiles that were performed below cloud base in the atmospheric boundary layer (ABL). In contrast to initial expectations of primary emissions, the vertical distribution of BC was mainly influenced by the stratification of the ABL during the WAM season. The article focuses on an event (14 and 15 July 2016) which showed distinct layers of BC in the lowermost 900 m above ground level (a.g.l.). Low concentrations of <span classCombining double low line""inline-formula"">NO<i>x</i></span> and <span classCombining double low line""inline-formula"">CO</span> were sampled at the Savè supersite near the aircraft measurements and suggested a marginal impact of local sources during the case study. The lack of primary BC emissions was verified by a comparison of the measured BC with the model COSMO-ART (Consortium for Small-scale Modelling-Aerosols and Reactive Trace gases) that was applied for the field campaign period. The modelled vertical profiles of BC led to the assumption that the measured BC was already altered, as the size was mainly dominated by the accumulation mode. Further, calculated vertical transects of wind speed and BC presume that the observed BC layer was transported from the south with maritime inflow but was mixed vertically after the onset of a nocturnal low-level jet at the measurement site. This report contributes to the scope of DACCIWA by linking airborne BC data with ground observations and a model, and it illustrates the importance of a more profound understanding of the interaction between BC and the ABL in the WAM region. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License."
"57202310367;57203225601;55931224400;57202886387;34880186500;","A convolutional neural network for classifying cloud particles recorded by imaging probes",2020,"10.5194/amt-13-2219-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084733836&doi=10.5194%2famt-13-2219-2020&partnerID=40&md5=e5be8b24cff21226458de5e354bc6e39","<p>During typical field campaigns, millions of cloud particle images are captured with imaging probes. Our interest lies in classifying these particles in order to compute the statistics needed for understanding clouds. Given the large volume of collected data, this raises the need for an automated classification approach. Traditional classification methods that require extracting features manually (e.g., decision trees and support vector machines) show reasonable performance when trained and tested on data coming from a unique dataset. However, they often have difficulties in generalizing to test sets coming from other datasets where the distribution of the features might be significantly different. In practice, we found that for holographic imagers each new dataset requires labeling a huge amount of data by hand using those methods. Convolutional neural networks have the potential to overcome this problem due to their ability to learn complex nonlinear models directly from the images instead of pre-engineered features, as well as by relying on powerful regularization techniques. We show empirically that a convolutional neural network trained on cloud particles from holographic imagers generalizes well to unseen datasets. Moreover, fine tuning the same network with a small number (256) of training images improves the classification accuracy. Thus, the automated classification with a convolutional neural network not only reduces the hand-labeling effort for new datasets but is also no longer the main error source for the classification of small particles.</p>. © Author(s) 2020."
"57216971714;57216967347;14321990600;55533645800;","Challenges in UAS-based TIR imagery processing: Image alignment and uncertainty quantification",2020,"10.3390/rs12101552","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085553807&doi=10.3390%2frs12101552&partnerID=40&md5=806bd81b4fb496863ac319579ae42989","Thermal infrared measurements acquired with unmanned aerial systems (UAS) allow for high spatial resolution and flexibility in the time of image acquisition to assess ground surface temperature. Nevertheless, thermal infrared cameras mounted on UAS suffer from low radiometric accuracy as well as low image resolution and contrast hampering image alignment. Our analysis aims to determine the impact of the sun elevation angle (SEA), weather conditions, land cover, image contrast enhancement, geometric camera calibration, and inclusion of yaw angle information and generic and reference pre-selection methods on the point cloud and number of aligned images generated by Agisoft Metashape. We, therefore, use a total amount of 56 single data sets acquired on different days, times of day, weather conditions, and land cover types. Furthermore, we assess camera noise and the effect of temperature correction based on air temperature using features extracted by structure from motion. The study shows for the first time generalizable implications on thermal infrared image acquisitions and presents an approach to perform the analysis with a quality measure of inter-image sensor noise. Better image alignment is reached for conditions of high contrast such as clear weather conditions and high SEA. Alignment can be improved by applying a contrast enhancement and choosing both, reference and generic pre-selection. Grassland areas are best alignable, followed by cropland and forests. Geometric camera calibration hampers feature detection and matching. Temperature correction shows no effect on radiometric camera uncertainty. Based on a valid statistical analysis of the acquired data sets, we derive general suggestions for the planning of a successful field campaign as well as recommendations for a suitable preprocessing workflow. © 2020 by the authors."
"57216346580;23970271800;57209470926;22954523900;8927405700;7003922583;","Spatiotemporal variability of solar radiation introduced by clouds over Arctic sea ice",2020,"10.5194/amt-13-1757-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083271324&doi=10.5194%2famt-13-1757-2020&partnerID=40&md5=e11be47bb312b13a3b74ad9b3e94f1b8","The role of clouds in recent Arctic warming is not fully understood, including their effects on the solar radiation and the surface energy budget. To investigate relevant small-scale processes in detail, the intensive Physical feedbacks of Arctic planetary boundary layer, Sea ice, Cloud and AerosoL (PASCAL) drifting ice floe station field campaign was conducted during early summer in the central arctic. During this campaign, the small-scale spatiotemporal variability of global irradiance was observed for the first time on an ice floe with a dense network of autonomous pyranometers. A total of 15 stations were deployed covering an area of 0.83 km×1.59 km from 4-16 June 2017. This unique, open-access dataset is described here, and an analysis of the spatiotemporal variability deduced from this dataset is presented for different synoptic conditions. Based on additional observations, five typical sky conditions were identified and used to determine the values of the mean and variance of atmospheric global transmittance for these conditions. Overcast conditions were observed 39.6 % of the time predominantly during the first week, with an overall mean transmittance of 0.47. The second most frequent conditions corresponded to multilayer clouds (32.4 %), which prevailed in particular during the second week, with a mean transmittance of 0.43. Broken clouds had a mean transmittance of 0.61 and a frequency of occurrence of 22.1 %. Finally, the least frequent sky conditions were thin clouds and cloudless conditions, which both had a mean transmittance of 0.76 and occurrence frequencies of 3.5 % and 2.4 %, respectively. For overcast conditions, lower global irradiance was observed for stations closer to the ice edge, likely attributable to the low surface albedo of dark open water and a resulting reduction of multiple reflections between the surface and cloud base. Using a wavelet-based multi-resolution analysis, power spectra of the time series of atmospheric transmittance were compared for single-station and spatially averaged observations and for different sky conditions. It is shown that both the absolute magnitude and the scale dependence of variability contains characteristic features for the different sky conditions. © 2020 Author(s)."
"57190982656;57199756429;57194420529;57216896801;7003831563;15063683000;","Observed near-storm environment variations across the southern Cumberland Plateau system in northeastern Alabama",2020,"10.1175/MWR-D-19-0190.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085219863&doi=10.1175%2fMWR-D-19-0190.1&partnerID=40&md5=dbc8c098d04b90027640a8165c06297d","The Sand Mountain and Lookout Mountain Plateaus in northeastern Alabama have been established as a regional relative maximum in tornadogenesis reports within the southeastern United States. Investigation of long-term surface datasets has revealed (i) stronger and more backed winds atop Sand Mountain than over the Tennessee Valley, and (ii) measured cloud-base heights are lower to the surface atop Sand Mountain than over the Tennessee Valley. These observations suggest that low-level wind shear and lifting condensation level (LCL) height changes may lead to conditions more favorable for tornadogenesis atop the plateaus than over the Tennessee Valley. However, prior to fall 2016, no intensive observations had been made to further investigate low-level flow or thermodynamic changes in the topography of northeastern Alabama. This paper provides detailed analysis of observations gathered during VORTEX-SE field campaign cases from fall 2016 through spring 2019. These observations indicate that downslope winds form along the northwest edge of Sand Mountain in at least some severe storm environments in northeastern Alabama. Wind profiles gathered across northeastern Alabama indicate that low-level helicity changes can be substantial over small distances across different areas of the topographic system. LCL height changes often scale to changes in land elevation, which can be on the order of 200-300 m across northeastern Alabama. © 2020 American Meteorological Society."
"55703847000;7601492669;56842269600;","Evaluation of an E-ϵ and three other boundary layer parameterization schemes in the WRF model over the southeast pacific and the Southern Great Plains",2020,"10.1175/MWR-D-19-0084.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082884389&doi=10.1175%2fMWR-D-19-0084.1&partnerID=40&md5=a6bc5b2b63a41bb366b51bf73fd25f37","To accurately simulate the atmospheric state within the planetary boundary layer (PBL) by PBL parameterization scheme in different regions with their dominant weather/climate regimes is important for global/regional atmospheric models. In this study, we introduce the turbulence kinetic energy (TKE) and TKE dissipation rate (ϵ) based 1.5-order closure PBL parameterization (E-ϵ, EEPS) in the Weather Research and Forecasting (WRF) Model. The performances of the newly implemented EEPS scheme and the existing Yonsei University (YSU) scheme, the University of Washington (UW) scheme, and Mellor-Yamada-Nakanishi-Niino (MYNN) scheme are evaluated over the stratocumulus dominated southeast Pacific (SEP) and over the Southern Great Plains (SGP) where strong PBL diurnal variation is common. The simulations by these PBL parameterizations are compared with various observations from two field campaigns: the Variability of American Monsoon Systems Project (VAMOS) Ocean-Cloud-Atmosphere-Land Study (VOCALS) in 2008 over the SEP and the Land-Atmosphere Feedback Experiment (LAFE) in 2017 over the SGP. Results show that the EEPS and YSU schemes perform comparably over both regions, while the MYNN scheme performs differently in many aspects, especially over the SEP. The EEPS (MYNN) scheme slightly (significantly) underestimates liquid water path over the SEP. Compared with observations, the UW scheme produces the best PBL height over the SEP. The MYNN produces too high PBL height over the western part of the SEP while both the YSU and EEPS schemes produce too low PBL and cloud-top heights. The differences among the PBL schemes in simulating the PBL features over the SGP are relatively small. © 2020 American Meteorological Society."
"56638280100;9537045600;36458602300;36552332100;55103330700;","Triple-Frequency Doppler Retrieval of Characteristic Raindrop Size",2020,"10.1029/2019EA000789","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082321119&doi=10.1029%2f2019EA000789&partnerID=40&md5=b0b9e82df526da2a39b1df543fb41eee","A retrieval for characteristic raindrop size and width of the drop size distribution (DSD) based on triple-frequency vertical Doppler radar measurements is developed. The algorithm exploits a statistical relation that maps measurements of the differential Doppler velocities at X and Ka and at Ka and W bands into the two aforementioned DSD moments. The statistical mapping has been founded on 7,900 hr of disdrometer-observed DSDs and their simulated Doppler velocities. Additionally, a retrieval of (Formula presented.) based only on (Formula presented.) measurements is also presented, and its performance is compared to the analogous algorithm exploiting (Formula presented.) data. The retrievals are tested using triple-frequency radar data collected during a recent field campaign held at the Juelich Observatory for Cloud Evolution (JOYCE, Germany) where in situ measurements of the DSD were carried out only few meters away from the vertically pointing radars. The triple-frequency retrieval is able to obtain (Formula presented.) with an uncertainty below 25% for (Formula presented.) ranging from 0.7 to 2.4 mm. Compared to previously published dual-frequency retrievals, the third frequency does not improve the retrieval for small (Formula presented.) ((Formula presented.) mm). However, it significantly surpasses the (Formula presented.) algorithm for larger (Formula presented.) (20% versus 50% bias at 2.25 mm). Also compared to (Formula presented.) method, the triple-frequency retrieval is found to provide an improvement of 15% in terms of bias for (Formula presented.) mm. The triple-frequency retrieval of (Formula presented.) performs with an uncertainty of 20–50% for (Formula presented.) mm, with the best performance for (Formula presented.) mm. © 2020. The Authors."
"57208274214;35119188100;14020751800;55704350200;57189294502;57202531041;35461763400;36106033000;15925588200;57191750766;36515307600;35774441900;57189368623;55942083800;7102084129;7004944088;57189215242;57190209035;","The challenge of simulating the sensitivity of the Amazonian cloud microstructure to cloud condensation nuclei number concentrations",2020,"10.5194/acp-20-1591-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079430665&doi=10.5194%2facp-20-1591-2020&partnerID=40&md5=cae25401c7265cdbfe97e32f5ac861c3","The realistic representation of aerosol-cloud interactions is of primary importance for accurate climate model projections. The investigation of these interactions in strongly contrasting clean and polluted atmospheric conditions in the Amazon region has been one of the motivations for several field campaigns, including the airborne ""Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems-Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (Global Precipitation Measurement) (ACRIDICON-CHUVA)"" campaign based in Manaus, Brazil, in September 2014. In this work we combine in situ and remotely sensed aerosol, cloud, and atmospheric radiation data collected during ACRIDICONCHUVA with regional, online-coupled chemistry-transport simulations to evaluate the model's ability to represent the indirect effects of biomass burning aerosol on cloud microphysical and optical properties (droplet number concentration and effective radius). We found agreement between the modeled and observed median cloud droplet number concentration (CDNC) for low values of CDNC, i.e., low levels of pollution. In general, a linear relationship between modeled and observed CDNC with a slope of 0.3 was found, which implies a systematic underestimation of modeled CDNC when compared to measurements. Variability in cloud condensation nuclei (CCN) number concentrations was also underestimated, and cloud droplet effective radii (reff) were overestimated by the model. Modeled effective radius profiles began to saturate around 500 CCN cm-3 at cloud base, indicating an upper limit for the model sensitivity well below CCN concentrations reached during the burning season in the Amazon Basin. Additional CCN emitted from local fires did not cause a notable change in modeled cloud droplet effective radii. Finally, we also evaluate a parameterization of CDNC at cloud base using more readily available cloud microphysical properties, showing that we are able to derive CDNC at cloud base from cloud-side remote-sensing observations. © 2020 Author(s)."
"56212055700;35551238800;35621058500;15319055900;57212453371;57212452751;54782898100;6602336571;6603934961;7003334425;","Evidence of the complexity of aerosol transport in the lower troposphere on the Namibian coast during AEROCLO-sA",2019,"10.5194/acp-19-14979-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076715450&doi=10.5194%2facp-19-14979-2019&partnerID=40&md5=5cc097d8617222fac202373f31327cfd","<p>The evolution of the vertical distribution and optical properties of aerosols in the free troposphere, above stratocumulus, is characterized for the first time over the Namibian coast, a region where uncertainties on aerosol-cloud coupling in climate simulations are significant. We show the high variability of atmospheric aerosol composition in the lower and middle troposphere during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) field campaign (22 August-12 September 2017) around the Henties Bay supersite using a combination of ground-based, airborne and space-borne lidar measurements. Three distinct periods of 4 to 7&thinsp;d are observed, associated with increasing aerosol loads (aerosol optical thickness at 550&thinsp;nm ranging from <span classCombining double low line""inline-formula"">ĝ1/40.2</span> to <span classCombining double low line""inline-formula"">ĝ1/40.7</span>), as well as increasing lofted aerosol layer depth and top altitude. Aerosols are observed up to 6&thinsp;km above mean sea level during the later period. Aerosols transported within the free troposphere are mainly polluted dust (predominantly dust mixed with smoke from fires) for the first two periods (22 August-1 September 2017) and smoke for the last part (3-9 September) of the field campaign. As shown by Lagrangian back-trajectory analyses, the main contribution to the aerosol optical thickness over Henties Bay is shown to be due to biomass burning over Angola. Nevertheless, in early September, the highest aerosol layers (between 5 and 6&thinsp;km above mean sea level) seem to come from South America (southern Brazil, Argentina and Uruguay) and reach Henties Bay after 3 to 6&thinsp;d. Aerosols appear to be transported eastward by the midlatitude westerlies and towards southern Africa by the equatorward moving cut-off low originating from within the westerlies. All the observations show a very complex mixture of aerosols over the coastal regions of Namibia that must be taken into account when investigating aerosol radiative effects above stratocumulus clouds in the southeast Atlantic Ocean.</p>. © Author(s) 2019."
"57189712592;55607020000;38762392200;56611366900;35849722200;","Distinct Impacts of Increased Aerosols on Cloud Droplet Number Concentration of Stratus/Stratocumulus and Cumulus",2019,"10.1029/2019GL085081","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075448325&doi=10.1029%2f2019GL085081&partnerID=40&md5=d17856bc2a3545d0314e4670ca8ceb3a","In situ aircraft measurements obtained during the RACORO field campaign are analyzed to study the aerosol effects on different cloud regimes. The results show that with increasing cloud condensation nuclei (CCN), cloud droplet number concentration (Nd) significantly increases in stratocumulus (Sc) while remains almost unchanged in cumulus (Cu). By using a new approach to strictly constrain the dynamics in Cu, we found that neither simultaneously changing cloud dynamics nor dilution of cloud water induced by entrainment-mixing can explain the observed insensitivity of Nd. The different degree of reduction in cloud supersaturation caused by increasing aerosols might be responsible for the observed different aerosol indirect effect between Sc and Cu. ©2019. American Geophysical Union. All Rights Reserved."
"30667558200;57193132723;6603925960;","The Cumulus and Stratocumulus CloudSat-CALIPSO Dataset (CASCCAD)",2019,"10.5194/essd-11-1745-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075728960&doi=10.5194%2fessd-11-1745-2019&partnerID=40&md5=34519406e6b18e16c6eb6d535d9dc0a6","Low clouds continue to contribute greatly to the uncertainty in cloud feedback estimates. Depending on whether a region is dominated by cumulus (Cu) or stratocumulus (Sc) clouds, the interannual low-cloud feedback is somewhat different in both spaceborne and large-eddy simulation studies. Therefore, simulating the correct amount and variation of the Cu and Sc cloud distributions could be crucial to predict future cloud feedbacks. Here we document spatial distributions and profiles of Sc and Cu clouds derived from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and CloudSat measurements. For this purpose, we create a new dataset called the Cumulus And Stratocumulus CloudSat-CALIPSO Dataset (CASCCAD), which identifies Sc, broken Sc, Cu under Sc, Cu with stratiform outflow and Cu. To separate the Cu from Sc, we design an original method based on the cloud height, horizontal extent, vertical variability and horizontal continuity, which is separately applied to both CALIPSO and combined CloudSat-CALIPSO observations. First, the choice of parameters used in the discrimination algorithm is investigated and validated in selected Cu, Sc and Sc-Cu transition case studies. Then, the global statistics are compared against those from existing passive- and active-sensor satellite observations. Our results indicate that the cloud optical thickness - as used in passive-sensor observations - is not a sufficient parameter to discriminate Cu from Sc clouds, in agreement with previous literature. Using clustering-derived datasets shows better results although one cannot completely separate cloud types with such an approach. On the contrary, classifying Cu and Sc clouds and the transition between them based on their geometrical shape and spatial heterogeneity leads to spatial distributions consistent with prior knowledge of these clouds, from ground-based, ship-based and field campaigns. Furthermore, we show that our method improves existing Sc-Cu classifications by using additional information on cloud height and vertical cloud fraction variation. Finally, the CASCCAD datasets provide a basis to evaluate shallow convection and stratocumulus clouds on a global scale in climate models and potentially improve our understanding of low-level cloud feedbacks. The CASCCAD dataset (Cesana, 2019, <a hrefCombining double low line""https://doi.org/10.5281/zenodo.2667637"">https://doi.org/10.5281/zenodo.2667637</a>) is available on the Goddard Institute for Space Studies (GISS) website at <span classCombining double low line""uri"">https://data.giss.nasa.gov/clouds/casccad/</span> (last access: 5 November 2019) and on the zenodo website at <span classCombining double low line""uri"">https://zenodo.org/record/2667637</span> (last access: 5 November 2019). © 2015 Royal Society of Chemistry. All rights reserved."
"55915364000;7403401100;57189377456;17341189400;8084443000;24081268200;8980175400;35771409400;","Aerosol-cloud closure study on cloud optical properties using remotely piloted aircraft measurements during a BACCHUS field campaign in Cyprus",2019,"10.5194/acp-19-13989-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075737330&doi=10.5194%2facp-19-13989-2019&partnerID=40&md5=b0644da5e9f4580b8a7bb9de5e296bfd","<p>In the framework of the EU-FP7 BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: Towards a Holistic UnderStanding) project, an intensive field campaign was performed in Cyprus (March 2015). Remotely piloted aircraft system (RPAS), ground-based instruments, and remote-sensing observations were operating in parallel to provide an integrated characterization of aerosol-cloud interactions. Remotely piloted aircraft (RPA) were equipped with a five-hole probe, pyranometers, pressure, temperature and humidity sensors, and measured vertical wind at cloud base and cloud optical properties of a stratocumulus layer. Ground-based measurements of dry aerosol size distributions and cloud condensation nuclei spectra, and RPA observations of updraft and meteorological state parameters are used here to initialize an aerosol-cloud parcel model (ACPM) and compare the in situ observations of cloud optical properties measured by the RPA to those simulated in the ACPM. Two different cases are studied with the ACPM, including an adiabatic case and an entrainment case, in which the in-cloud temperature profile from RPA is taken into account. Adiabatic ACPM simulation yields cloud droplet number concentrations at cloud base (approximately 400&thinsp;cm<span classCombining double low line""inline-formula"">-3</span>) that are similar to those derived from a Hoppel minimum analysis. Cloud optical properties have been inferred using the transmitted fraction of shortwave radiation profile measured by downwelling and upwelling pyranometers mounted on a RPA, and the observed transmitted fraction of solar radiation is then compared to simulations from the ACPM. ACPM simulations and RPA observations shows better agreement when associated with entrainment compared to that of an adiabatic case. The mean difference between observed and adiabatic profiles of transmitted fraction of solar radiation is 0.12, while this difference is only 0.03 between observed and entrainment profiles. A sensitivity calculation is then conducted to quantify the relative impacts of 2-fold changes in aerosol concentration, and updraft to highlight the importance of accounting for the impact of entrainment in deriving cloud optical properties, as well as the ability of RPAs to leverage ground-based observations for studying aerosol-cloud interactions.</p>. © 2019 American Institute of Physics Inc.. All rights reserved."
"56965949500;7005263785;19337612500;54783792600;6603431534;6701333444;","A new approach to estimate supersaturation fluctuations in stratocumulus cloud using ground-based remote-sensing measurements",2019,"10.5194/amt-12-5817-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074689301&doi=10.5194%2famt-12-5817-2019&partnerID=40&md5=54439e58db2a299e7bfe970cd50720b5","Supersaturation, crucial for cloud droplet activation and condensational growth, varies in clouds at different spatial and temporal scales. In-cloud supersaturation is poorly known and rarely measured directly. On the scale of a few tens of meters, supersaturation in clouds has been estimated from in situ measurements assuming quasi-steady-state supersaturation. Here, we provide a new method to estimate supersaturation using ground-based remote-sensing measurements, and results are compared with those estimated from aircraft in situ measurements in a marine stratocumulus cloud during the Aerosol and Cloud Experiment (ACE-ENA) field campaign. Our method agrees reasonably well with in situ estimations, and it has three advantages: (1) it does not rely on the quasi-steady-state assumption, which is questionable in clean or turbulent clouds, (2) it can provide a supersaturation profile, rather than just point values from in situ measurements, and (3) it enables building statistics of supersaturation in stratocumulus clouds for various meteorological conditions from multi-year ground-based measurements. The uncertainties, limitations, and possible applications of our method are discussed. © Author(s) 2019."
"57202786441;7102601428;57208689231;","Crop Height Estimation Using RISAT-1 Hybrid-Polarized Synthetic Aperture Radar Data",2019,"10.1109/JSTARS.2019.2919604","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072647804&doi=10.1109%2fJSTARS.2019.2919604&partnerID=40&md5=c6aed87da0c9937515d2e1e0535966ec","The objective of this paper was to explore the potential of hybrid-polarized (RH and RV) RISAT-1 SAR data to retrieve the height of wheat crop - an important winter crop in South Asian countries including India. The images acquired over north-west India in 2015 covered critical growth stages of wheat. The field campaigns were carried out in synchronous with the SAR passes. Considering the dominant role of underlying soil cover in the total backscatter (σ total0) response from a target, we propose that refining the σ total}}^0 by reducing the effect of underlying soil can significantly improve the retrieval accuracy of crop height (CH). To achieve this, we modified the existing water cloud model (WCM) to estimate soil-corrected vegetation backscatter (σveg0). Leaf area index and interaction factor showed great potential as the vegetation descriptors in modeling σtotal0 using WCM. A comparative analysis between the CH retrieved from σtotal0 and σ veg0 using multilayer perceptron neural networks revealed the response of C-band backscatter to CH. CH was moderately correlated to σtotal0, but the results improved considerably with the substitution of σtotal0 with σveg0. This holds true particularly in the early growth stages of crop growth when the vegetation cover is scarce and there is a substantial effect of soil background on the remote sensing signal. Thus, the results suggest suitability of C-band hybrid-polarized data for the assessment of CH. © 2008-2012 IEEE."
"8719703500;24759591600;35567153700;7003535385;8700289500;36842724800;48662824200;56537827700;7003475277;6506234624;","Analysis and Automated Detection of Ice Crystal Icing Conditions Using Geostationary Satellite Datasets and in Situ Ice Water Content Measurements",2019,"10.4271/2019-01-1953","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067917345&doi=10.4271%2f2019-01-1953&partnerID=40&md5=b285239cb0aa0837f79380f4753d0514","Recent studies have found that high mass concentrations of ice particles in regions of deep convective storms can adversely impact aircraft engine and air probe (e.g. pitot tube and air temperature) performance. Radar reflectivity in these regions suggests that they are safe for aircraft penetration, yet high ice water content (HIWC) is still encountered. The aviation weather community seeks additional remote sensing methods for delineating where ice particle (or crystal) icing conditions are likely to occur, including products derived from geostationary (GEO) satellite imagery that is now available in near-real time at increasingly high spatio-temporal detail from the global GEO satellite constellation. A recent study using a large sample of co-located GEO satellite and in-situ isokinetic evaporator probe (IKP-2) total water content (TWC) datasets found that optically thick clouds with tops near to or above the tropopause in close proximity (≤ 40 km) to convective updrafts were most likely to contain high TWC (TWC ≥ 1 g m-3). These parameters are detected using automated algorithms and combined to generate a HIWC probability (PHIWC) product at the NASA Langley Research Center (LaRC). Seven NASA DC-8 aircraft flights were conducted in August 2018 over the Gulf of Mexico and the tropical Pacific Ocean during the HIWC Radar II field campaign. The convection sampled during four flights was observed by GOES-16 at 1- or 5-minute intervals, providing the first opportunity to analyze product performance from this new satellite. This paper will (1) present initial comparisons between GOES-16 and IKP-2 datasets during HIWC Radar II, (2) demonstrate GOES-16 products for select periods when high TWC was encountered with an emphasis on three flights with 1-minute imagery, (3) compare GOES observations and derived products from the HIWC Radar I and II campaigns. © 2019 SAE International; NASA Glenn Research Center."
"14019399400;6506537159;6701592014;57203233100;57198616562;8723505700;24322892500;","Estimates of entrainment in closed cellular marine stratocumulus clouds from the MAGIC field campaign",2019,"10.1002/qj.3514","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063589176&doi=10.1002%2fqj.3514&partnerID=40&md5=4656b26a8a900522999eb70317b1c4ee","Entrainment of warm, dry air from above the boundary layer into the cloud layer has a significant impact on stratocumulus clouds in the marine boundary layer. During the MAGIC field campaign, the Atmospheric Radiation Measurement (ARM) mobile facility was deployed aboard a container ship that made regular transects between Los Angeles, California and Honolulu, Hawaii. Observations made during MAGIC transects were collocated with observations from the Geostationary Operational Environmental Satellite (GOES-15) and European Centre for Medium-range Weather Forecasting (ECMWF) reanalysis model. From these data, hourly estimates of entrainment velocities in closed cellular stratocumulus cloud conditions were calculated from the mixed-layer mass budget equation, modified to accommodate observations sampled from a moving platform. The technique is demonstrated using observations collected during Leg 15A (46 h) and then extended to 178 h of data. The average entrainment velocity was 7.83 ± 5.23 mm/s, and the average large-scale vertical air motion at cloud top (obtained from reanalysis) was −2.56 ± 3.31 mm/s. The vertical air motion at cloud top was positive (upward) during 36 h (∼20%) with a mean of 2.68 mm/s. Entrainment velocity is highly variable and on average the MAGIC observations show no dependence of entrainment velocity on longitude or any pronounced diurnal cycle. When binned by inversion strength, the mean entrainment velocity and mean large-scale vertical air motion mirrored each other, with both exhibiting substantial variability. Collectively, our results suggest a mean entrainment-velocity behaviour associated with the background state, with large changes in entrainment velocity forced by strong variability in internal boundary-layer properties like turbulence, radiation, and inversion strength. This cautions against using climatological mean estimates of entrainment velocities or neglecting instances with upward large-scale vertical air motion. © 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57207252885;57207256232;57202054858;57207260025;","Evaluation of Windsond S1H2 performance in Kumasi during the 2016 DACCIWA field campaign",2019,"10.5194/amt-12-1311-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062351002&doi=10.5194%2famt-12-1311-2019&partnerID=40&md5=751ec48910e1cd839d831f97509762b3","Sparv Embedded, Sweden (http://windsond.com, last access: 22 February 2019), has answered the call for less expensive but accurate reusable radiosondes by producing a reusable sonde primarily intended for boundary-layer observations collection: The Windsond S1H2. To evaluate the performance of the S1H2, in-flight comparisons between the Vaisala RS41-SG and Windsond S1H2 were performed during the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project (FP7/2007-2013) ground campaign at the Kumasi Agromet supersite (6°40'45.76"" N, 1°33'36.50"" W) inside the Kwame Nkrumah University of Science and Technology (KNUST), Ghana, campus. The results suggest a good correlation between the RS41-SG and S1H2 data, the main difference lying in the GPS signal processing and the humidity response time at cloud top. Reproducibility tests show that there is no major performance degradation arising from S1H2 sonde reuse. © 2019 Author(s)."
"55684491100;","The horizontal spectrum of vertical velocities near the tropopause from global to gravity wave scales",2019,"10.1175/JAS-D-19-0160.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076393469&doi=10.1175%2fJAS-D-19-0160.1&partnerID=40&md5=30101a2ffa5208e764f81583f4e4e84e","Vertical motions are fundamental for atmospheric dynamics. Compared to horizontal motions, the horizontal spectrum of vertical velocity w is less well known. Here, w spectra are related to spectra of horizontal motions in the free atmosphere near the tropopause from global to gravity wave scales. At large scales, w is related to vertically averaged horizontal divergent motions by continuity. At small scales, the velocity energy spectra reach anisotropy as in stably stratified turbulence. Combining these limits approximates the w spectrum from global to small scales. The w spectrum is flat at large scales when the divergent spectrum shows a -2 slope, reaches a maximum at mesoscales after transition to -5/3 slopes, and then approaches a fraction of horizontal kinetic energy. The ratio of vertical kinetic energy to potential energy increases quadratically with wavenumber at large scales. It exceeds unity at small scales in stratified turbulence. Global and regional simulations and two recent aircraft measurement field campaigns support these relationships within 30% deviations. Energy exchange between horizontal and vertical motions may contribute to slope changes in the spectra. The model allows for checking measurement validity. Isotropy at large and small scales varies between the datasets. The fraction of divergent energy is 40%-70%in the measurements, with higher values in the stratosphere. Spectra above the tropopause are often steeper over mountains than over oceans, partly with two -5/3 subranges. A total of 80% of w variance near the tropopause occurs at scales between about 0.5 and 80 km. © 2019 American Meteorological Society."
"57212816521;7102101132;","Mesoscale processes during the genesis of Hurricane Karl (2010)",2019,"10.1175/JAS-D-18-0161.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075582796&doi=10.1175%2fJAS-D-18-0161.1&partnerID=40&md5=fb3c795629161bd8b5bbd4dfb874df10","Observations from the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT), Genesis and Rapid Intensification Processes (GRIP), and Intensity Forecast Experiment (IFEX) field campaigns are analyzed to investigate the mesoscale processes leading to the tropical cyclogenesis of Hurricane Karl (2010). Research aircraft missions provided Doppler radar, in situ flight level, and dropsonde data documenting the structural changes of the predepression disturbance. Following the pre-Karl wave pouch, variational analyses at the meso-b and meso-a scales suggest that the convective cycle in Karl alternately built the low- and midlevel circulations leading to genesis episodically rather than through a sustained lowering of the convective mass flux from increased stabilization. Convective bursts that erupt in the vorticity-rich environment of the recirculating pouch region enhance the low-level meso-b- and meso-a-scale circulation through vortex stretching. As the convection wanes, the resulting stratiform precipitation strengthens the midlevel circulation through convergence associated with ice microphysical processes, protecting the disturbance from the intrusion of dry environmental air. Once the column saturation fraction returns to a critical value, a subsequent convective burst below the midlevel circulation further enhances the low-level circulation, and the convective cycle repeats. The analyses suggest that the onset of deep convection and associated low-level spinup were closely related to the coupling of the vorticity and moisture fields at low and midlevels. Our interpretation of the observational analysis presented in this study reaffirms a primary role of deep convection in the genesis process and provides a hypothesis for the supporting role of stratiform precipitation and the midlevel vortex. © 2019 American Meteorological Society."
"57190441282;36057442400;38762392200;9275665400;","Sensitivity of lake-effect cloud microphysical processes to ice crystal habit and nucleation during OWLeS IOP4",2019,"10.1175/JAS-D-19-0004.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075570618&doi=10.1175%2fJAS-D-19-0004.1&partnerID=40&md5=e979b118c4fc7cc118b61ed48cd869e3","Ice crystal habit significantly impacts ice crystal processes such as growth by vapor deposition. Despite this, most bulk microphysical models disregard this natural shape effect and assume ice to grow spherically. This paper focuses on how the evolution of ice crystal shape and choice of ice nucleation parameterization in the adaptive habit microphysics model (AHM) influence the lake-effect storm that occurred during intensive observing period 4 (IOP4) of the Ontario Winter Lake-effect Systems (OWLeS) field campaign. This localized snowstorm produced total accumulated liquid-equivalent precipitation amounts up to 17.92 mm during a 16-h time period, providing a natural laboratory to investigate the ice–liquid partitioning within the cloud, various microphysical process rates, the accumulated precipitation magnitude, and its associated spatial distribution. Two nucleation parameterizations were implemented, and aerosol data from a size-resolved advanced particle microphysics (APM) model were ingested into the AHM for use in parameterizing ice and cloud condensation nuclei. Simulations allowing ice crystals to grow nonspherically produced 1.6%–2.3% greater precipitation while altering the nucleation parameterization changed the type of accumulating hydrometeors. In addition, all simulations were highly sensitive to the domain resolution and the source of initial and boundary conditions. These findings form the foundational understanding of relationships among ice crystal habit, nucleation parameterizations, and resultant cold-season mesoscale precipitation within detailed bulk microphysical models allowing adaptive habit. © 2019 American Meteorological Society."
"57198593283;57206332144;8225489800;","Cloud Edge Properties Measured by the ARM Shortwave Spectrometer Over Ocean and Land",2019,"10.1029/2019JD030622","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070724893&doi=10.1029%2f2019JD030622&partnerID=40&md5=26f5c7d146db03f9e3862c5dddbcd780","We use the spectrally invariant method to study the variability of cloud optical thickness (τ) and droplet effective radius (reff) in transition zones between the cloudy and clear-sky columns observed by Shortwave Array Spectroradiometer-Zenith at the Southern Great Plains Central Facility site (SGP C1) and during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The spectrally invariant method approximates the spectra in the transition zone as a linear combination of definitely clear and definitely cloudy spectra. The slope and intercept of the linear relations characterize τ and reff in the transition region, respectively. The radiative transfer model simulations show that that (i) the slope of the visible band is positively correlated with τ, while (ii) the intercept of the near-infrared band has a high negative correlation with reff. We have analyzed 22 cloud edge cases from the SGP and MAGIC and found that from cloud to clear in the transitions, (a) the slopes of the visible band decrease, indicating the decrease of τ toward cloud edges, and (b) the intercepts of the near-infrared band show a much more significant increase at the SGP than from the MAGIC. The results from observed cases suggest that while τ decreases for all cases, the decrease in reff is much more significant for cloud over land at the SGP site compared to the ocean counterpart during the MAGIC campaign. ©2019. American Geophysical Union. All Rights Reserved."
"25924499900;25647939800;","Resolution dependencies of tropical convection in a global cloud/cloud-system resolving model",2019,"10.2151/jmsj.2019-034","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067818266&doi=10.2151%2fjmsj.2019-034&partnerID=40&md5=c93168f28422d491e728560a85e89138","The properties of tropical convection are evaluated using one-month long simulation datasets produced by the non-hydrostatic icosahedral atmospheric model (NICAM) using 3.5-, 7-, and 14-km horizontal meshes with identical cloud-microphysics configurations. The simulations are targeted on the 2nd Madden-Julian oscillation (MJO) event observed in the CINDY2011/DYNAMO field campaign. An increase in high cloud fraction at 200 hPa level and a reduction in surface precipitation occur as the horizontal resolution increases, corresponding to the reduction in precipitation efficiency due to the shorter residence time inside stronger updrafts that occur at the higher resolution. The increase in high cloud fraction is followed by the warming of the troposphere, which results in an increase in the column water vapor and an elevation in the freezing level. The total water condensation is decreased at higher resolutions, which is likely due to a balance with the decreased outgoing longwave radiation (OLR). The reproduced MJOs, which accounted for a large portion of the tropical convections, were similar in the 3.5-km and 14-km simulations in terms of eastward propagation speeds and structures, including the characteristic westward tilt of the moisture anomaly with height. However, the amplitude of the anomalous MJO circulation was considerably smaller in the 3.5-km simulation. The robust resolution dependence and the interpretations presented in this study underline the necessity for a resolution-aware cloud-microphysics optimization method that will have value in the coming era of global cloud-resolving simulations. © The Author(s) 2019."
"25122625000;7004372407;35759804100;57203805666;7102609908;","Determination of Intraseasonal Variation of Precipitation Microphysics in the Southern Indian Ocean from Joss–Waldvogel Disdrometer Observation during the CINDY Field Campaign",2018,"10.1007/s00376-018-8026-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053006831&doi=10.1007%2fs00376-018-8026-5&partnerID=40&md5=08cb8c6078c9019ef18886d0c4ee67e0","To date, the intraseasonal variation of raindrop size distribution (DSD) in response to the Madden–Julian Oscillation (MJO) has been examined only over the Indonesian Maritime Continent, particularly in Sumatra. This paper presents the intraseasonal variation of DSD over the Indian Ocean during the Cooperative Indian Ocean experiment on Intraseasonal Variability in the Year 2011 (CINDY 2011) field campaign. The DSDs determined using a Joss–Waldvogel disdrometer, which was installed on the roof of the anti-rolling system of the R/V Mirai during stationary observation (25 September to 30 November 2011) at (8°S, 80.5°E), were analyzed. The vertical structure of precipitation was revealed by Tropical Rainfall Measuring Mission Precipitation Radar (version 7) data. While the general features of vertical structures of precipitation observed during the CINDY and Sumatra observation are similar, the intraseasonal variation of the DSD in response to the MJO at each location is slightly different. The DSDs during the active phase of the MJO are slightly broader than those during the inactive phase, which is indicated by a larger mass-weighted mean diameter value. Furthermore, the radar reflectivity during the active MJO phase is greater than that during the inactive phase at the same rainfall rate. The microphysical processes that generate large-sized drops over the ocean appear to be more dominant during the active MJO phase, in contrast to the observations made on land (Sumatra). This finding is consistent with the characteristics of radar reflectivity below the freezing level, storm height, bright band height, cloud effective radius, and aerosol optical depth. © 2018, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature."
"55655454900;6507728803;","A regression-free rainfall estimation algorithm for dual-polarization radars",2018,"10.1175/JTECH-D-17-0201.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052528450&doi=10.1175%2fJTECH-D-17-0201.1&partnerID=40&md5=89f3ba219939a2d5506a2d51925b7f1f","In this study a new radar rainfall estimation algorithm-rainfall estimation using simulated raindrop size distributions (RESID)-was developed. This algorithm development was based upon the recent finding that measured and simulated raindrop size distributions (DSDs) with matching triplets of dual-polarization radar observables (i.e., horizontal reflectivity, differential reflectivity, and specific differential phase) produce similar rain rates. The RESID algorithm utilizes a large database of simulated gamma DSDs, theoretical rain rates calculated from the simulated DSDs, the corresponding dual-polarization radar observables, and a set of cost functions. The cost functions were developed using both the measured and simulated dual-polarization radar observables. For a given triplet of measured radar observables, RESID chooses a suitable cost function from the set and then identifies nine of the simulated DSDs from the database that minimize the value of the chosen cost function. The rain rate associated with the given radar observable triplet is estimated by averaging the calculated theoretical rain rates for the identified simulated DSDs. This algorithm is designed to reduce the effects of radar measurement noise on rain-rate retrievals and is not subject to the regression uncertainty introduced in the conventional development of the rain-rate estimators. The rainfall estimation capability of our new algorithm was demonstrated by comparing its performance with two benchmark algorithms through the use of rain gauge measurements from the Midlatitude Continental Convective Clouds Experiment (MC3E) and the Olympic Mountains Experiment (OLYMPEx). This comparison showed favorable performance of the new algorithm for the rainfall events observed during the field campaigns. © 2018 American Meteorological Society."
"57194795787;35567569600;","Seasonal evolution of soil and plant parameters on the agricultural Gebesee test site: A database for the set-up and validation of EO-LDAS and satellite-aided retrieval models",2018,"10.5194/essd-10-525-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043782467&doi=10.5194%2fessd-10-525-2018&partnerID=40&md5=4ac2b70b295db7151a636dbe8310b762","Ground reference data are a prerequisite for the calibration, update, and validation of retrieval models facilitating the monitoring of land parameters based on Earth Observation data. Here, we describe the acquisition of a comprehensive ground reference database which was created to test and validate the recently developed Earth Observation Land Data Assimilation System (EO-LDAS) and products derived from remote sensing observations in the visible and infrared range. In situ data were collected for seven crop types (winter barley, winter wheat, spring wheat, durum, winter rape, potato, and sugar beet) cultivated on the agricultural Gebesee test site, central Germany, in 2013 and 2014. The database contains information on hyperspectral surface reflectance factors, the evolution of biophysical and biochemical plant parameters, phenology, surface conditions, atmospheric states, and a set of ground control points. Ground reference data were gathered at an approximately weekly resolution and on different spatial scales to investigate variations within and between acreages. In situ data collected less than 1 day apart from satellite acquisitions (RapidEye, SPOT 5, Landsat-7 and-8) with a cloud coverage ≤ 25% are available for 10 and 15 days in 2013 and 2014, respectively. The measurements show that the investigated growing seasons were characterized by distinct meteorological conditions causing interannual variations in the parameter evolution. Here, the experimental design of the field campaigns, and methods employed in the determination of all parameters, are described in detail. Insights into the database are provided and potential fields of application are discussed. The data will contribute to a further development of crop monitoring methods based on remote sensing techniques. The database is freely available at PANGAEA (a hrefCombining double low line https://doi.org/10.1594/PANGAEA.874251 targetCombining double low line""-blank"">https://doi.org/10.1594/PANGAEA.874251;). © 2018 Author(s)."
"6602122304;","Characterization of Mixed-Phase Clouds: Contributions From the Field Campaigns and Ground Based Networks",2018,"10.1016/B978-0-12-810549-8.00005-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041197259&doi=10.1016%2fB978-0-12-810549-8.00005-2&partnerID=40&md5=4556cf10ef32d042f338e04f8cc20d30","Clouds and their associated microphysical processes regulate the atmospheric radiative transfer and the hydrological cycle. Mixed-phase clouds are an important component of the Earth cloud system, and their radiative effects are dependent on water phase partitioning. These clouds present particular challenges for observations and modeling, and their accurate representation in numerical models is essential for weather and climate simulations. The physical properties of mixed-phase clouds are derived mainly from aircraft observations, ground-based monitoring networks such as Atmospheric Radiation Measurement (ARM) Program and Cloudnet, and from satellites equipped with remote sensing instruments. This chapter presents a perspective on the main field experiments and ground-based networks during the last decades that resulted in improved characterization of mixed-phase clouds. © 2018 Elsevier Inc. All rights reserved."
"57192311544;7202843160;45961453200;","ICESat-derived lithospheric flexure as caused by an endorheic lake's expansion on the Tibetan Plateau and the comparison to modeled flexural responses",2017,"10.1016/j.jseaes.2017.08.028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033397089&doi=10.1016%2fj.jseaes.2017.08.028&partnerID=40&md5=e8940ed08005edb84177564c47557076","A substantial and rapid expansion beginning in the late 1990s of Siling Co, the largest endorheic lake on the central Tibetan Plateau (TP), has caused a measurable lithospheric deflection in the region adjacent to the lake. Current broad-scale measuring of this flexural response is mainly derived from InSAR processing techniques or time-consuming field campaigns. The rheological constraints of the lithosphere from the underlying lithospheric response to large lake loads in this region are not well understood. This paper highlights a more efficient spaceborne LiDAR remote sensing technique to measure the deflection in the vicinity of Siling Co and to investigate the mechanisms of the observed lithospheric response in order to garner a better understanding of the local rheology. A lake-adjacent deflection rate and Siling Co water load variations are calculated utilizing the Geoscience Laser Altimeter System (GLAS) onboard NASA's Ice, Cloud and land Elevation Satellite (ICESat) and the joint NASA/USGS Landsat series of Earth observing satellites. A downward deflection rate of ∼5.6 mm/yr for the first 4 km of lake-adjacent land is calculated from the GLAS instrument, and this response is compared to the flexural outputs from a spherically symmetric, non-rotating, elastic, and isotropic (SNREI) Earth model in order to better understand the underlying mechanisms of the lithospheric response to the rapid increase of Siling Co loads. The modeled elastic response is ∼6.9 times lower than the GLAS derived flexure, thereby providing further evidence that a purely elastic lithospheric response cannot explain the deflection in this region. The relationship between the modeled elastic response and the GLAS derived flexure is applied to a long-term lake load change dataset to create the longest-running flexural response curve as caused by the last ∼40 years of Siling Co load variations, and these results show an accumulated lake-adjacent flexure of ∼12.6 cm from an overall lake load increase of 25.9 Gt. Our findings help to provide a better understanding of the lithospheric response to the recent expansion of Siling Co by introducing a new spaceborne laser altimeter derived technique to measure surface deformation caused by an extreme case of hydrologic loading. © 2017 Elsevier Ltd"
"36803253000;56931957400;20435752700;7003886299;6603591733;","Enhanced humidity pockets originating in the mid boundary layer as a mechanism of cloud formation below the lifting condensation level",2017,"10.1088/1748-9326/aa5ba4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015779961&doi=10.1088%2f1748-9326%2faa5ba4&partnerID=40&md5=a94c33b978b7a63c04f4373766e83ad8","A ground-based field campaign was conducted during the summer of 2011, 10 km east of the Israeli coast, aimed at studying small, warm convective clouds. During the campaign, clouds were detected on days that were predicted to be cloud-free by standard forecasting methods. Moreover, the clouds' bases were often much lower than the estimated lifting condensation level. Detailed air parcel model simulations revealed that such small non-buoyant clouds can form only if the convective motion is driven by perturbations in the relative humidity in the middle of the boundary layer, rather than by temperature perturbations near the surface. Furthermore, cloud base height exhibited weak sensitivity to the initial elevation of the parcel, suggesting that it serves as an accumulation point for many relative-humidity-perturbed thermodynamic trajectories. Such a mechanism is likely to be common under atmospheric conditions of a hot and humid boundary layer capped by a strong inversion layer. © 2017 IOP Publishing Ltd."
"13204619900;8891521600;7004364155;35361704100;7103116704;","The role of DYNAMO in situ observations in improving NASA CERES-like daily surface and atmospheric radiative flux estimates",2017,"10.1002/2016EA000248","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042551975&doi=10.1002%2f2016EA000248&partnerID=40&md5=4b53028defb79d8569360815202fe04b","The daily surface and atmospheric radiative fluxes from NASA Clouds and the Earth’s Radiant Energy System (CERES) Synoptic 1 degree (SYN1deg) Ed3A are among the most widely used data to study cloud-radiative feedback. The CERES SYN1deg data are based on Fu-Liou radiative transfer computations that use specific humidity (Q) and air temperature (T) from NASA Global Modeling and Assimilation Office (GMAO) reanalyses as inputs and are therefore subject to the quality of those fields. This study uses in situ Q and T observations collected during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign to augment the input stream used in the NASA GMAO reanalysis and assess the impact on the CERES daily surface and atmospheric longwave estimates. The results show that the assimilation of DYNAMO observations considerably improves the vertical profiles of analyzed Q and T over and near DYNAMO stations by moistening and warming the lower troposphere and upper troposphere and drying and cooling the mid-upper troposphere. As a result of these changes in Q and T, the computed CERES daily surface downward longwave flux increases by about 5 W m2, due mainly to the warming and moistening in the lower troposphere; the computed daily top-of-atmosphere (TOA) outgoing longwave radiation increases by 2–3Wm2 during dry periods only. Correspondingly, the estimated local atmospheric longwave radiative cooling enhances by about 5 W m2 (7–8Wm2) during wet (dry) periods. These changes reduce the bias in the CERES SYN1deg-like daily longwave estimates at both the TOA and surface and represent an improvement over the DYNAMO region. © 2017. The Authors."
"56061814400;7801595201;55481777500;13406672500;7005706662;12801992200;","Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime",2015,"10.5194/acpd-15-29347-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956653468&doi=10.5194%2facpd-15-29347-2015&partnerID=40&md5=82868fe78657d07127283ab7b1cc8b1a","There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood, as changes in atmospheric conditions due to aerosol may change the expected magnitude of indirect effects by altering cloud properties in unexpected ways. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season. In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements of atmospheric precipitable water vapor and the liquid water path (LWP) of trade cumulus clouds were made, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol. Here we present evidence of a positive correlation between aerosol and cloud LWP which becomes clear after the data are filtered to control for the natural meteorological variability in the region. We then use the aircraft and ground observatory measurements to explore the mechanisms behind the observed aerosol-LWP correlation. We determine that increased boundary-layer humidity lowering the cloud base is responsible for the observed increase in cloud liquid water. Large-scale analysis indicates that high pollution cases originate with a highly-polluted boundary layer air mass approaching the observatory from a northwesterly direction. This polluted mass exhibits higher temperatures and humidity than the clean case, the former of which may be attributable to heating due to aerosol absorption of solar radiation over the subcontinent. While high temperature conditions dispersed along with the high-aerosol anomaly, the high humidity condition was observed to instead develop along with the polluted air mass. We then explore potential causal mechanisms of the observed correlations, though future research will be needed to more fully describe the aerosol-humidity relationship. � Author(s) 2015."
"55707289500;56363987000;54393349200;7103204204;6603382350;57209490771;7005941217;6603315547;57190209035;","Spectral optical layer properties of cirrus from collocated airborne measurements - A feasibility study",2015,"10.5194/acpd-15-19045-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962543969&doi=10.5194%2facpd-15-19045-2015&partnerID=40&md5=7979f57fbcba7a8b2994309a3d7d13b6","Spectral optical layer properties of cirrus are derived from simultaneous and vertically collocated measurements of spectral upward and downward solar irradiance above and below the cloud layer and concurrent in situ microphysical sampling. From the irradiance data spectral transmissivity, absorptivity, reflectivity, and cloud top albedo of the observed cirrus layer are obtained. At the same time microphysical properties of the cirrus were sampled. The close collocation of the radiative and microphysical measurements, above, beneath and inside the cirrus, is obtained by using a research aircraft (Learjet 35A) in tandem with a towed platform called AIRTOSS (AIRcraft TOwed Sensor Shuttle). AIRTOSS can be released from and retracted back to the research aircraft by means of a cable up to a distance of 4 km. Data were collected in two field campaigns above the North and Baltic Sea in spring and late summer 2013. Exemplary results from one measuring flight are discussed also to illustrate the benefits of collocated sampling. Based on the measured cirrus microphysical properties, radiative transfer simulations were applied to quantify the impact of cloud particle properties such as crystal shape, effective radius r eff , and optical thickness τ on cirrus optical layer properties. The effects of clouds beneath the cirrus are evaluated in addition. They cause differences in the layer properties of the cirrus by a factor of 2 to 3, and for cirrus radiative forcing by up to a factor of 4. If low-level clouds below cirrus are not considered the solar cooling due to the cirrus is significantly overestimated. © Author(s) 2015."
"16444324800;7801483847;56433656000;57151345600;55896920900;6505856601;16066726600;56358933300;36573180000;57213493573;","The Use of RDT Nowcasting Tool for Detecting Convective Areas Associated with High Ice Water Content during HAIC/HIWC Field Campaign",2015,"10.4271/2015-01-2124","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959553748&doi=10.4271%2f2015-01-2124&partnerID=40&md5=1173a7dfdff35bee1c8afffb713f41cc","Glaciated icing conditions potentially leading to in-service event are often encountered in the vicinity of deep convective clouds. Nowcasting of these conditions with space-borne observations would be of a great help for improving flight safety and air-traffic management but still remains challenging. In the framework of the HAIC (High Altitude Ice Crystals) project, methods to detect and track regions of high ice water content from space-based geostationary and low orbit mission are investigated. A first HAIC/HIWC field campaign has been carried out in Australia in January-March 2014 to sample meteorological conditions potentially leading to glaciated icing conditions. During the campaign, several nowcasting tools were successfully operated such as the Rapid Development Thunderstorm (RDT) product that detects the convective areas from infrared geostationary imagery. The RDT tracks clouds, identifies those that are convective, and provides a temporal and spatial description of their microphysical, morphological and dynamical properties. Comparison of in-situ measurements collected during the HAIC 2014 flights show that there is a good detection of convective cells, and most of the time, high concentration of ice water content was found inside the contours of convection delimited by RDT. Investigations on how to optimize RDT to improve detection rate on convective cells that contain high ice water content, to constrain precisely convective areas to their minimal size and to characterise missed convective cells are conducted. For this, a study is carried out, that combines ice water content satellite estimates from different algorithms with RDT. Copyright © 2015 SAE International."
"35113492400;56611366900;24765069600;55272477500;","Scale dependence of entrainment-mixing mechanisms in cumulus clouds",2014,"10.1002/2014JD022265","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018747027&doi=10.1002%2f2014JD022265&partnerID=40&md5=4d11dcf87d4773741188addd7809fb50","This work empirically examines the dependence of entrainment-mixing mechanisms on the averaging scale in cumulus clouds using in situ aircraft observations during the Routine Atmospheric Radiation Measurement Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign. A new measure of homogeneous mixing degree is defined that can encompass all types of mixing mechanisms. Analysis of the dependence of the homogenous mixing degree on the averaging scale shows that, on average, the homogenous mixing degree decreases with increasing averaging scales, suggesting that apparent mixing mechanisms gradually approach from homogeneous mixing to extreme inhomogeneous mixing with increasing scales. The scale dependence can be well quantified by an exponential function, providing first attempt at developing a scale-dependent parameterization for the entrainment-mixing mechanism. The influences of three factors on the scale dependence are further examined: droplet-free filament properties (size and fraction), microphysical properties (mean volume radius and liquid water content of cloud droplet size distributions adjacent to droplet-free filaments), and relative humidity of entrained dry air. It is found that the decreasing rate of homogeneous mixing degree with increasing averaging scales becomes larger with larger droplet-free filament size and fraction, larger mean volume radius and liquid water content, or higher relative humidity. The results underscore the necessity and possibility of considering averaging scale in representation of entrainment-mixing processes in atmospheric models. © 2014. American Geophysical Union. All Rights Reserved."
"8581784200;8540777600;","Integration of undergraduate education and field campaigns: A case study from deep convective clouds and chemistry",2014,"10.1175/BAMS-D-13-00209.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84919460303&doi=10.1175%2fBAMS-D-13-00209.1&partnerID=40&md5=32cf1a86291ab34135c24bc1f278fc02","The University of North Dakota (UND) partnered with the Deep Convective Clouds and Chemistry (DC3) campaign, the National Science Foundation, and the University of Alabama in Huntsville (UAH)to provide undergraduate students with an experiential learning opportunity that uniquely integrated classroom activities, operational forecasting, and a large multiagency field campaign. The class forecasting experience was tailored specifically to the DC3 campaign by focusing on specialized regional convective forecasts using data from the previous spring's operations. The students developed criteria based on campaign goals and flight safety considerations that were deemed crucial for operations decisions: storm morphology, time of initiation, nearness to other storm complexes, and storm depth. The live briefings were also appreciated by the students as an opportunity to hear how campaigns are run and how their own discussions might compare with those by the DC3 forecast team. The course successfully utilized an experiential learning paradigm, providing students with experience in forecasting, field campaign decision making, and model evaluation."
"6505856601;8413672100;55523304700;6603624776;6602283489;57206307062;7003303758;8689787200;24401929100;","Properties of the lightning activity at storm scale during HYMEX SOP1 campaign: Comparison between an isolated storm (05 Sept 2012), a multi-cellular system (24 Sept 2012) and a tornadic cell (14 Oct 2012)",2014,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086814082&partnerID=40&md5=5678c1b6e8d895fcb3c277a7e196725c","During the HyMeX (Hydrology cycle in the Mediterranean Experiment) SOP1 (Special Observation Period 1; September-November 2012) campaign, the New Mexico Tech Lightning Mapping Array in conjunction with four European operational lightning detection networks (ATDNET, UKMO; EUCLID; LINET, nowcast; ZEUS, NOA) recorded the total lightning activity over South-Eastern France. We present here observations collected during three different weather situations: one isolated thunderstorm occurring on the 5th of September, a multi-cellular system on the 24th of September (HyMeX IOP6 case) and the 14 November tornadic cell. So far the analysis of the lightning data has been focusing on some specific parameters or features like flash density, convection surge or intra-cloud ratio. We first briefly describe the instrumentation operated during the field campaign and the methodology applied to analyze the data. Some properties of the lightning activity (e.g. flash rate, intra-cloud ratio, altitude of flash triggering) are then discussed according to the type and the stage of convective clouds and related to the properties of the parent clouds as derived from concurrent radar and satellite observations. Further investigations on relating the lightning activity to the cloud properties are currently underway and results will be presented during the conference. © International Conference on Atmospheric Electricity, ICAE 2014"
"35305673400;","Observations of the marine boundary layer under a cutoff low over the southeast Pacific Ocean",2014,"10.1007/s00703-013-0292-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84891645195&doi=10.1007%2fs00703-013-0292-2&partnerID=40&md5=760f2642b4375a3ae7b912fe58542ea1","Stratocumulus is often present offshore of Peru and northern Chile and exists at the top of a cool, moist and well-mixed marine boundary layer (MBL) under a marked temperature inversion maintained by large-scale subsidence. The subtropical MBL and stratocumulus has been the focus of many recent studies, but mid-latitude systems can exert a strong influence. However, this connection is not well established due to debatable model results and few in situ measurements south of 20°S. During a 2-week field campaign in August 2011 at Robinson Crusoe Island (~700 km offshore at 33.6°S), radiosondes were launched to observe the response of the MBL to mid-latitude synoptic forcing. During the observation period a broad, slow-moving cutoff low (COL) passed over the region. Other observations include COSMIC GPS, infrared satellite imagery, TRMM radar reflectivity, and operational radiosondes from the Chilean weather service. A numerical simulation is included to diagnose the synoptic features. The inversion prior to the COL was maintained and lifted above 5 km as the COL passed over the island. Soon after the COL center passed the island, the MBL top did not descend or reform near the surface and then deepen, but rather an inversion reformed at ~2.7 km. Using a variety of datasets, the height of the reformation of the inversion is related to the cloud top height of the scattered shallow cumulus convection under the COL, which coincides with the level of maximum convergence of the vertical velocity. © 2013 Springer-Verlag Wien."
"7202258620;7203001286;55720332500;6701463335;7403143315;7005361537;7003430284;6603260116;","Impact of Aerosol Activation on Modelled Regional Particulate Matter Mass and Size Distribution Due to Cloud Processing",2013,"10.1007/978-94-007-5577-2_23","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885416078&doi=10.1007%2f978-94-007-5577-2_23&partnerID=40&md5=f511a1b7810794ce3ca92c60c2addc72","Aerosol activation is a key process in aerosol-AQ cloud interaction. Although it is widely studied within the climate modeling community it has not been attracting significant attention within the air quality modeling community. In this study an off-line, sectional, chemically-speciated regional air quality model, AURAMS, has been used to assess the impact of aerosol activation on the modelled regional particulate matter (PM) mass concentration and size distribution. Asimple activation scheme based on an empirical relationship between cloud droplet number density and aerosol number density is compared to a more physically-based activation scheme. Model simulations were compared to aircraft observations obtained during the 2004 ICARTT field campaign. Modelled aerosol light extinction and column aerosol optical depth (AOD) were computed in three different ways in the current study. Two of them based on Mie calculations and one empirical reconstructed mass extinction method. The magnitude of the modeled AOD varies significantly depending on the approach. The impact of different aerosol activation schemes on the modelled AOD in this case is generally in the range of 20-30 % for the two Mie methods. As the empirical reconstructed mass extinction method is not size dependent, it is less sensitive to aerosol activation. © Springer Science+Business Media Dordrecht 2014."
"57212020824;7401796996;57212022036;57212020452;","Effects of Clouds and Aerosols on Surface Radiation Budget Inferred from DOE AMF at Shouxian, China",2013,"10.1080/16742834.2013.11447049","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075751436&doi=10.1080%2f16742834.2013.11447049&partnerID=40&md5=8bb4866ef6cf01982efdcca37bce2ac8","Based on data collected during the first U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) field campaigns at Shouxian, eastern China in 2008, the effects of clouds and aerosols on the surface radiation budget during the period October–December 2008 were studied. The results revealed that the largest longwave (LW), shortwave (SW), and net Aerosol Radiative Effects (AREs) are 12.7, –37.6, and –24.9 W m–2, indicating that aerosols have LW warming impact, a strong SW cooling effect, and a net cooling effect on the surface radiation budget at Shouxian during the study period 15 October–15 December 2008. The SW cloud radiative forcing (CRF) is –135.1 W m–2, much cooler than ARE (about 3.6 times), however, the LW CRF is 43.6 W m–2, much warmer than ARE, and resulting in a net CRF of –91.5 W m–2, about 3.7 times of net ARE. These results suggest that the clouds have much stronger LW warming effect and SW cooling effect on the surface radiation budget than AREs. The net surface radiation budget is dominated by SW cooling effect for both ARE and CRF. Furthermore, the precipitatable clouds (PCs) have the largest SW cooling effect and LW warming effect, while optically thin high clouds have the smallest cooling effect and LW warming on the surface radiation budget. Comparing the two selected caseds, CloudSat cloud radar reflectivity agrees very well with the AMF (ARM Mobile Facility) WACR (W-band ARM Cloud Radar) measurements, particularly for cirrus cloud case. These result will provide a ground truth to validate the model simulations in the future. © 2013, © 2013 Institute of Atmospheric Physics, Chinese Academy of Sciences."
"55823844500;7201906181;7003371185;57195452780;","Validation of the MODIS reflectance product under UK conditions",2013,"10.1080/01431161.2013.820363","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84881636525&doi=10.1080%2f01431161.2013.820363&partnerID=40&md5=16b336b87396e8e377a0d3b6adb942e8","Surface reflectance obtained from remote-sensing data is the main input to almost all remote-sensing applications. The availability and special characteristics of Moderate Resolution Imaging Spectroradiometer (MODIS) products have led to their use worldwide. Validation of the MODIS reflectance product is then crucial to provid information on uncertainty in the reflectance data, and in other MODIS products and in the applied surface-atmosphere models. Compact Airborne Spectrographic Imager (CASI) and Système Pour l'Observation de la Terre (SPOT) data, collected during the Network for Calibration and Validation in Earth Observation (NCAVEO) 2006 Field Campaign, were applied to validate daily MODIS reflectance data over a site in the southern UK. The difference in the view geometry of at-nadir CASI and SPOT data and off-nadir MODIS data was dealt with using a semi-empirical bidirectional reflectance distribution function (BRDF) model. The validation results showed that for our particular study site, the absolute errors in the MODIS reflectance product were too large to allow the albedo data to be used directly in climate models. The errors were mainly related to the uncertainties in the MODIS atmospheric variables, the BRDF model, and undetected clouds and cloud shadows. More generally, the study highlights the extreme difficulty of achieving pixel-level validation of coarse spatial resolution satellite sensor data in an environment in which the atmosphere is constantly changing, and in which the landscape is characterized by high space-time heterogeneity. © 2013 Copyright 2013 Taylor & Francis."
"24174769200;55778527900;6603855330;7004588253;","Gully evolution in agricultural fields using ground-based LiDAR",2011,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861603101&partnerID=40&md5=b9e7dd1533f69bdbfe11db305311ed89","Meeting the increasing demand for agricultural products is dependent on maintaining productive soils. Gully erosion in agricultural fields, has been shown in many regions to be as significant as sheet and rill erosion in delivering sediment to streams, rivers and lakes. Soil loss from all erosion sources is also much higher when gullies are present. Integrated conservation practices are needed to effectively control erosion from all sources in agricultural watersheds. In order to understand the effect of these practices, studies are necessary to improve our understanding of the processes involved in the formation and evolution of gullies in agricultural fields. Studies were performed to monitor gullies in a small catchment located in Kansas, USA through multi-temporal surveys using a ground-based Light Detection and Ranging (LiDAR) system to produce detailed topographic information (Figure 1). Elevation data, in the form of point clouds, obtained in each field campaign (surveys at different dates) were filtered to remove anomalous points representing vegetation and standing crop residue. Multitemporal detailed terrain models were generated using irregular grids and gully evolution was quantified by measurements of headcut migration, channel widening and volume change estimation. Although the findings of this study represent short-term morphological changes, these results demonstrate the potential for using sequential detailed Digital Elevation Models (DEMs) for long-term monitoring of the dynamic behavior of gullies located in agricultural fields, providing information for developing/validating gully evolution theories thus improving the development of conservation practices."
"6603770689;57201410408;7403331283;6507557020;","Multi-doppler measurements of atmospheric rotors and turbulent mountain waves",2008,"10.1109/IGARSS.2008.4779313","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649810181&doi=10.1109%2fIGARSS.2008.4779313&partnerID=40&md5=b8f04dc27cd0f936c9fb3d4bf08735e2","Radar measurements of reflectivity and Doppler velocity for selected cases of rotors and turbulence associated with mountain waves from 2006 T-REX and NASA06 field campaigns are analyzed. The data were collected with the Wyoming Cloud Radar (WCR, http://atmos.uwyo.edu/wcr) on board the University of Wyoming King Air research aircraft (UWKA, https://atmos.uwyo.edu/n2uw). The retrieval of single- Doppler vertical velocity at 30 m resolution above and below the aircraft and two-dimensional (2-D), high-resolution (on the order of 40x40 m2) Dual-Doppler, vertical velocity fields below the aircraft are discussed. The results demonstrate complex dynamics occurring within mountain cap and roll/rotor clouds. Turbulent dynamics and small-scale vortices, without the presence of a larger-scale organized vortex, appear to be more prevalent below mountain wave crests at low levels. The analysis of radar data from consecutive passes during mountain wave events also suggests that while the terrain-induced waves exhibit both stationary and non-stationary behavior, there is a significant evolution in the turbulent dynamics under mountain wave crests and individual features/vortices have a variable life span (on the order of minutes to tens of minutes). The reflectivity fields reveal a disorganized and turbulent structure of the scatterers in the roll clouds. When scatterers are present below the roll cloud (e.g., due to precipitation) their distribution is highly non-uniform. Our radar data does not resolve the 3rd dimension (across these flight tracks) and thus some 2-D assumptions are made. The three-dimensionality of the terrain may influence the mountain wave structure and dynamics, but our assumptions are reasonable for flow structures generated by long mountain ranges. © 2008 IEEE."
"8657684100;57189196985;35550463300;6602940217;6701907704;56391214800;23670308500;","A cloudless land atmosphere radiosounding database for generating land surface temperature retrieval algorithms",2007,"10.1109/IGARSS.2007.4423196","https://www.scopus.com/inward/record.uri?eid=2-s2.0-82355190867&doi=10.1109%2fIGARSS.2007.4423196&partnerID=40&md5=eea109c9b18846d014c82993d092c8ee","A database of global, cloud-free, atmospheric radiosounding profiles was compiled with the aim of simulating radiometric measurements from satellite-borne sensors in the thermal infrared. The objective of the simulation is to generate split-window (SW) and dual-angle (DA) algorithms for the retrieval of land surface temperature (LST) from Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) and Envisat/Advanced Along Track Scanning Radiometer (AATSR) data. The database contains 382 radiosonde profiles acquired over land, with nearly-uniform distribution of precipitable water between O and 5.5 cm. Radiative transfer calculations were performed with the MODTRAN 4 code. Different viewing angles were considered in the simulation, taking into account the features of each sensor. The viewing capability of AATSR, with near simultaneous observations first at a forward angle (55° from nadir) and then close to nadir, allows the implementation of DA algorithms. Using the simulation database, SW algorithms adapted for MODIS and AATSR data, and DA algorithms for AATSR data were developed. Both types of algorithms are quadratic in the brightness temperature difference, and depend explicitly on the land surface emissivity. A sensitivity analysis of all algorithms was made to obtain estimation of the algorithm errors. Furthermore the SW and DA algorithms developed from the simulation database were validated with actual ground measurements of LST collected, concurrently to MODIS and AATSR observations, in a site located close to the city of Valencia, Spain, in a large, flat and thermally homogeneous area of rice crops, where field campaigns were held during the summers of 2002-2006. Operational LST algorithms of each sensor were also validated in order to compare with the algorithms generated. © 2007 IEEE."
"34882294600;7404495164;7403476075;","A method to retrieve soil moisture using ERS Scatterometer data",2007,"10.1109/IGARSS.2007.4423185","https://www.scopus.com/inward/record.uri?eid=2-s2.0-82355165108&doi=10.1109%2fIGARSS.2007.4423185&partnerID=40&md5=7c40ff59ff83727d35160deefdb7b200","Soil moisture is a key component in the hydrologie cycle and climate system. It is an important input parameter for many hydrologie and meteorological models. Taking the advantage of the multi-incident angles of the ERS Wind Scatterometer(WSC), a new soil moisture retrieving method, that significantly improves the surface backscattering presentation, is proposed in this study based on the Advanced Integral Equation Model (AIEM) and the Water-Cloud model. It utilizes the correlations in each backscattering components (bare soil and vegetation) for the simultaneous measurements of each incident angle pairs to reduce the effect of surface roughness and vegetation scattering on soil moisture estimation. The result is validated by using the ground measurements from the Intensive Observation Period (IOP'98) field campaign in 1998 of GAME/Tibet in the end of this paper, and the time series of the estimated soil moisture shows a consistent trend with those sampled on the ground. © 2007 IEEE."
"7003765782;7006218162;13406305400;15033928900;6701862401;55477384200;15033525400;6603604042;6505759999;7006483900;55902740300;","Vertical distribution of water vapor in the Arctic stratosphere in January-February 2004 from data of the LAUTLOS field campaign",2005,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-27644541566&partnerID=40&md5=081836049841428b8e878f90b6e9b674","The results of measurements of water-vapor vertical profiles in the upper troposphere and lower stratosphere on board a meteorological sounding balloon with the use of a FLASH-B optical fluorescent hygrometer are presented. These results were obtained during the LAUTLOS-WAVVAP international experiment on the comparison of balloon hygrometers, which was carried out in January-February 2004 in northern Finland. Humidity values are determined inside, outside, and at the boundary of the circumpolar stratospheric cyclone. It is shown that, at a height of 20 km, the difference between the mixing ratios of water vapor outside and inside the cyclone can attain 1 ppm and increases with height. It is inferred that the layered structure of the vertical humidity profile at the stratospheric-cyclone boundary is caused by inhomogeneous advection of air masses. The humidity-profile layering is in good agreement with the layering of the potential-vorticity profile, which points to the dynamic nature of these layers. It is shown that decreased values of the water-vapor content observed in the polar stratosphere are not always controlled by dehydration processes associated with the formation and sedimentation of particles of polar stratospheric clouds. Copyright © 2005 by MAIK ""Nauka/Interperiodica"" (Russia)."
"6602751071;9233163800;56264191700;6701412834;6603004389;7006368713;","SAFIRE-A (spectroscopy of the atmosphere by using far-infrared emission-airborne): Assessment of measurement capabilities and future developments",2005,"10.1016/j.asr.2005.03.109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-27744515146&doi=10.1016%2fj.asr.2005.03.109&partnerID=40&md5=78c49b3777c9ca5fbfb0c9ca1fa2c9c0","New measurement capabilities of the SAFIRE-A airborne spectrometer, based on a polarisation sensing optical scheme and suitable for investigation of aerosols and clouds properties, have been implemented and tested in a field campaign. The polarisation measuring configuration is described here with respect to the instrument layout for intensity measurements deployed in several scientific missions to study the chemistry and dynamics of the upper troposphere and lowermost stratosphere. First results of the novel experimental set-up, obtained during the APE-GAIA Antarctic campaign, are presented and discussed and possible measurement scenarios, relying on synergistic use of SAFIRE-A intensity and polarisation measuring modes, are envisaged for future applications. © 2005 COSPAR. Published by Elsevier Ltd. All rights reserved."
"7003415852;","Cloud characterization at DYCOMS II from MCR observations",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036399428&partnerID=40&md5=8dc18b609c30d08cbb944e93d6fb3e44","NCAR's Multichannel Cloud Radiometer (MCR) is a downward-looking scanning radiometer with seven spectral bands. The MCR has flown aboard the NSF/NCAR C-130 during several field campaigns, including the Dynamics and Chemistry of Marine Stratocumulus II (DYCOMS II) experiment, which took place off the coast of southern California during July 2001. In this paper, two near-infrared MCR channels are utilized to determine the cloud liquid water content and cloud drop effective radius during this experiment. To obtain these cloud characteristics from MCR observations, a radiative transfer model is used to compute the expected radiances for a variety of cloud liquid water contents and effective radii. This program incorporates the atmospheric and surface oceanic conditions that were observed by the C-130. The simulated radiances are computed for the two MCR bands, and compared to the observed values. This comparison yields an estimate of cloud liquid water content and cloud drop effective radius. The cloud properties derived using this technique are compared to C-130 in situ observations and to estimates derived from satellite observations of marine stratocumulus in the same area observed during DYCOMS II."
"57210590791;7102543010;57073563800;7003945447;7006577245;7004125528;7004084412;","Vertical plane velocity fields retrieved from dual-beam airborne Doppler radar data",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032644780&partnerID=40&md5=95de615f996c5e429bde39f6666f9eed","The Turbulence et Circulations Coherentes Dans La Couche Limite Atmospherique (TRAC98) field campaign was initiated to develop coherent structures in the boundary layer, and the early development of convection. Flights took place 80 km south of Paris. This report details results from dual-Doppler analyses of two cases observed during the TRAC98 project."
"56125241300;57219626438;57219626011;57214318900;","Raindrop size distribution measurements on the Southeast Tibetan Plateau during the STEP project",2021,"10.1016/j.atmosres.2020.105311","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094323983&doi=10.1016%2fj.atmosres.2020.105311&partnerID=40&md5=38a8baeae9cd5b57b195a64418ce3832","As part of the Second Tibetan Plateau Scientific Expedition and Research (STEP) field campaign, raindrop size distribution (DSD) measurements were conducted with a laser optical particle size velocity disdrometer in Motuo on the Tibetan Plateau (TP). The DSD characteristics of five different rain rate classes and convective and stratiform precipitation types were studied using the DSD data from July to September 2019, comprising a total of 47,774 1-min raindrop spectra. The average raindrop spectral width and number concentration of large drops increased with the rainfall intensity. Furthermore, the combination of small- and midsize drops dominated the precipitation in Motuo, and their contributions exceeded 99% of the number concentration. The convective precipitation in Motuo was identified as maritime-like precipitation and was characterized by a large normalized intercept parameter log10Nw = 4.0–4.4 and small mass-weighted mean diameter Dm = 1.1–1.4 mm. Empirical relations among the three parameters (intercept N0, shape μ, and slope Λ) of the gamma distribution model, Nw and Dm of the normalized gamma distribution were derived. We also obtained power-law relationships of Z = ARb for the stratiform and convective precipitation in Motuo, and the empirical relation of Z = 300R1.4 significantly underestimated the convective precipitation in Motuo. When the precipitation type transitioned from stratiform into convective precipitation, coefficient A decreased and exponent b increased. Finally, empirical relations between Dm and the radar equivalent reflectivity factor at the Ku and Ka bands were obtained to improve the rainfall retrieval algorithms of the dual-frequency precipitation radar on the southeast TP. © 2020 The Authors"
"6603579524;6603812137;6603269674;57218794903;57218795981;21739916500;57203331186;57194445359;7004870145;","On the conditions for winter lightning at the Eagle Nest Tower (2537 m asl) during the Cerdanya-2017 field experiment",2021,"10.1016/j.atmosres.2020.105208","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090294875&doi=10.1016%2fj.atmosres.2020.105208&partnerID=40&md5=907e5a1f4c7df5ce565a664cd782bf14","In this paper, we analyze meteorological conditions, thundercloud structure, lightning activity and characteristics of the flashes that strike two towers separated by 1.3 km on Tosa d'Alp (2537 m asl) for two days (March 24 and 31) of the Cerdanya-2017 field campaign. Remote sensing products (cloud top temperature, lightning flash location, volumetric radar scans) and a set of sensors installed at Cerdanya station (electric field mill, microwave radiometer, vertically-pointing K-band Doppler radar, atmospheric soundings) provide the data for the analysis. A total of 20 flashes (72 strokes) have been detected on these towers with a large majority on March 24 (18 flashes and 66 strokes), despite of a lower convective activity in the study region. All these flashes are negative and most of them exhibit the features of upward flashes: large multiplicity (3.67 in average on March 24), strokes with low peak current (−10.6 kA in average on March 24), and short inter-stroke time interval (40 ms in average on March 24). Some flashes are supposed to be self-triggered on the towers because of the absence (the low number) of VHF sources before (after) the strokes. Compared to the instrumented “Eagle Nest Tower”, the “Cerdanya Tardia Antenna” collects a greater number of flashes (strokes) during the most prolific day with 14 out of 18 (57 out of 66). During this day, all flashes that radiate in VHF at less than 5 km from the towers strike them. We observe also that the cloud region around −15 °C favorable for charging process is located at lower altitude (1000 m above tower altitude) and produce strong radar reflectivity values on that day. Furthermore, the wind at the altitude of Tosa d'Alp stronger on March 24 could facilitate the inception from the towers by evacuating the corona ions. © 2020 Elsevier B.V."
"56212055700;35621058500;57212452751;35551238800;35509639400;","Trade-wind clouds and aerosols characterized by airborne horizontal lidar measurements during the EUREC4A field campaign",2020,"10.5194/essd-12-2919-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096495077&doi=10.5194%2fessd-12-2919-2020&partnerID=40&md5=49f348d18dc11974f6cc0b9b9aea22d5","From 23 January to 13 February 2020, 20 manned research flights were conducted over the tropical Atlantic, off the coast of Barbados (13◦300 N, 58◦300 W), to characterize the trade-wind clouds generated by shallow convection. These flights were conducted as part of the international EUREC4A (Elucidating the role of cloud–circulation coupling in climate) field campaign. One of the objectives of these flights was to characterize the trade-wind cumuli at their base for a range of meteorological conditions, convective mesoscale organizations and times of the day, with the help of sidewards-staring remote sensing instruments (lidar and radar). This paper presents the datasets associated with horizontal lidar measurements. The lidar sampled clouds from a lateral window of the aircraft over a range of about 8 km, with a horizontal resolution of 15 m, over a rectangle pattern of 20 km by 130 km. The measurements made possible the characterization of the size distribution of clouds near their base and the presence of dust-like aerosols within and above the marine boundary layer. This paper presents the measurements and the different levels of data processing, ranging from the raw Level 1 data (https://doi.org/10.25326/57; Chazette et al., 2020c) to the Level 2 and Level 3 processed data that include a horizontal cloud mask (https://doi.org/10.25326/58; Chazette et al., 2020b) and aerosol extinction coefficients (https://doi.org/10.25326/59; Chazette et al., 2020a). An intermediate level, companion to Level 1 data (Level 1.5), is also available for calibrated and geolocalized data (https://doi.org/10.25326/57; Chazette et al., 2020c). © Author(s) 2020. This work is distributed under"
"57038767400;9839353600;14821846300;","Surface and subsurface characterisation of salt pans expressing polygonal patterns",2020,"10.5194/essd-12-2881-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096207673&doi=10.5194%2fessd-12-2881-2020&partnerID=40&md5=29aa76b69f072027def68c583839a083","The data set described here contains information about the surface, subsurface, and environmental conditions of salt pans that express polygonal patterns in their surface salt crust (Lasser et al., 2020b; https://doi.org/10.5880/fidgeo.2020.037). Information stems from 5 field sites at Badwater Basin and 21 field sites at Owens Lake both in central California. All data were recorded during two field campaigns from between November and December 2016 and in January 2018. Crust surfaces, including the mean diameter and fluctuations in the height of the polygonal patterns, were characterised by a terrestrial laser scanner (TLS). The data contain the resulting three-dimensional point clouds that describe these surfaces. The subsurface is characterised by grain size distributions of samples taken from depths between 5 and 100 cm below the salt crust and measured with a laser particle size analyser. Subsurface salinity profiles were recorded, and the groundwater density was also measured. Additionally, the salts present in the crust and pore water were analysed to determine their composition. To characterise the environmental conditions at Owens Lake, including the differences between nearby crust features, records were made of the temperature and relative humidity during 1 week in November 2016. The field sites are characterised by images showing the general context of each site, such as pictures of selected salt polygons, including any which were sampled, a typical core from each site at which core samples were taken, and close-ups of the salt crust morphology. Finally, two videos of salt crust growth over the course of spring 2018 and reconstructed from time lapse images are included. © 2020 Copernicus GmbH. All rights reserved."
"55338801300;6602087140;37056101400;55996365900;49861577800;7404747615;7202060229;57219965866;35547214900;8627503500;56423657500;","Models transport Saharan dust too low in the atmosphere: A comparison of the MetUM and CAMS forecasts with observations",2020,"10.5194/acp-20-12955-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096302531&doi=10.5194%2facp-20-12955-2020&partnerID=40&md5=0eaae725a53db0992c17e414689964dd","We investigate the dust forecasts from two operational global atmospheric models in comparison with in situ and remote sensing measurements obtained during the AERosol properties - Dust (AER-D) field campaign. Airborne elastic backscatter lidar measurements were performed on board the Facility for Airborne Atmospheric Measurements during August 2015 over the eastern Atlantic, and they permitted us to characterise the dust vertical distribution in detail, offering insights on transport from the Sahara. They were complemented with airborne in situ measurements of dust size distribution and optical properties, as well as datasets from the Cloud-Aerosol Transport System (CATS) spaceborne lidar and the Moderate Resolution Imaging Spectroradiometer (MODIS). We compare the airborne and spaceborne datasets to operational predictions obtained from the Met Office Unified Model (MetUM) and the Copernicus Atmosphere Monitoring Service (CAMS). The dust aerosol optical depth predictions from the models are generally in agreement with the observations but display a low bias. However, the predicted vertical distribution places the dust lower in the atmosphere than highlighted in our observations. This is particularly noticeable for the MetUM, which does not transport coarse dust high enough in the atmosphere or far enough away from the source. We also found that both model forecasts underpredict coarse-mode dust and at times overpredict fine-mode dust, but as they are fine-tuned to represent the observed optical depth, the fine mode is set to compensate for the underestimation of the coarse mode. As aerosol-cloud interactions are dependent on particle numbers rather than on the optical properties, this behaviour is likely to affect their correct representation. This leads us to propose an augmentation of the set of aerosol observations available on a global scale for constraining models, with a better focus on the vertical distribution and on the particle size distribution. Mineral dust is a major component of the climate system; therefore, it is important to work towards improving how models reproduce its properties and transport mechanisms. © Author(s) 2020."
"57190300360;7202257926;57212816521;57193999542;55682851300;57193958103;6505932008;","Updraft vertical velocity observations and uncertainties in high plains supercells using radiosondes and radars",2020,"10.1175/MWR-D-20-0071.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095916994&doi=10.1175%2fMWR-D-20-0071.1&partnerID=40&md5=d292cd1e0e7b9bd11b9be62ec5e9b3ab","Observations of the air vertical velocities (wair) in supercell updrafts are presented, including uncertainty estimates, from radiosonde GPS measurements in two supercells. These in situ observations were collected during the Colorado State University Convective Cloud Outflows and Updrafts Experiment (C3LOUD-Ex) in moderately unstable environments in Colorado and Wyoming. Based on the radiosonde accelerations, instances when the radiosonde balloon likely bursts within the updraft are determined, and adjustments are made to account for the subsequent reduction in radiosonde buoyancy. Before and after these adjustments, the maximum estimated wair values are 36.2 and 49.9 m s21, respectively. Radar data are used to contextualize the in situ observations and suggest that most of the radiosonde observations were located several kilometers away from the most intense vertical motions. Therefore, the radiosonde-based wair values presented likely underestimate the maximum values within these storms due to these sampling biases, as well as the impacts from hydrometeors, which are not accounted for. When possible, radiosonde-based wair values were compared to estimates from dual-Doppler methods and from parcel theory. When the radiosondes observed their highest wair values, dual-Doppler methods generally produced 15–20 m s21 lower wair for the same location, which could be related to the differences in the observing systems’ resolutions. In situ observations within supercell updrafts, which have been limited in recent decades, can be used to improve our understanding and modeling of storm dynamics. This study provides new in situ observations, as well as methods and lessons that could be applied to future field campaigns. © 2020 American Meteorological Society."
"57208100965;56548964400;6506597473;57213353924;","Monitoring soil surface roughness under growing winter wheat with low-altitude UAV sensing: Potential and limitations",2020,"10.1002/esp.4998","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091313200&doi=10.1002%2fesp.4998&partnerID=40&md5=0f39b7c2041b0bc9467c9014c779f22d","Soil surface roughness (SSR) is an important factor in controlling sediment and runoff generation, influencing directly a wide spectrum of erosion parameters. SSR is highly variable in time and space under natural conditions, and characterizing SSR to improve the parameterization of hydrological and erosion models has proved challenging. Our study uses recent technological and algorithmic developments in capturing and processing close aerial sensing data to evaluate how high-resolution imagery can assist the temporally and spatially explicit monitoring of SSR. We evaluated the evolution of SSR under natural rainfall and growing vegetation conditions on two arable fields in Denmark. Unmanned aerial vehicle (UAV) photogrammetry was used to monitor small field plots over 7 months after seeding of winter wheat following conventional and reduced tillage treatments. Field campaigns were conducted at least once a month from October until April, resulting in nine time steps of data acquisition. Structure from motion photogrammetry was used to derive high-resolution point clouds with an average ground sampling distance of 2.7 mm and a mean ground control point accuracy of 1.8 mm. A comprehensive workflow was developed to process the point clouds, including the detection of vegetation and the removal of vegetation-induced point cloud noise. Rasterized and filtered point clouds were then used to determine SSR geostatistically as the standard deviation of height, applying different kernel sizes and using semivariograms. The results showed an influence of kernel size on roughness, with a value range of 0.2–1 cm of average height deviation during the monitoring period. Semivariograms showed a measurable decrease in sill variance and an increase in range over time. This research demonstrated multiple challenges to measuring SSR with UAV under natural conditions with increasing vegetation cover. The proposed workflow represents a step forward in tackling those challenges and provides a knowledge base for future research. © 2020 John Wiley & Sons, Ltd. © 2020 John Wiley & Sons, Ltd."
"57142867400;6506328135;34772240500;57193213111;57218291394;","Characterization of Surface Heterogeneity-Induced Convection Using Cluster Analysis",2020,"10.1029/2020JD032550","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094133768&doi=10.1029%2f2020JD032550&partnerID=40&md5=1058cd2e424b6836de2e34e1096b5f46","Land-atmosphere interactions and boundary layer processes often control the formation of shallow clouds and subsequently deep convective precipitation over the U.S. Southern Great Plains. In this study, we examine the impacts of large-scale advection on the cloud populations and land-atmospheric coupling observed during the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems field campaign in 2016. We performed two large eddy simulations using the Weather Research and Forecasting Model for a day in which the transition from clear-sky to shallow precipitating clouds and isolated deep convection was observed. The control simulation reproduced the overall distribution of cloud populations by using realistic soil conditions with an interactive land model. In the sensitivity simulation where large-scale advection is removed, a strong relationship between the land and boundary layer is found. To study the timing, location, and intensity of convective initiation and the relationship of clouds with land surface properties, a cluster analysis of equivalent potential temperature is performed for the simulation without large-scale advection. That analysis shows that convective clouds first form over regions with higher surface sensible heat flux. Precipitation from those convective clouds likely triggers new updrafts nearby about 2 hr later through the lifting associated with cold pools. The cluster analysis also shows that in addition to the spatial pattern of soil moisture, land use and soil texture in western Oklahoma also influence the location of convective initiation. ©2020. American Geophysical Union. All Rights Reserved."
"57219595454;57202055245;57195588502;56816641500;7006033615;6602725432;7003811754;","A Climatology of the Marine Atmospheric Boundary Layer Over the Southern Ocean From Four Field Campaigns During 2016–2018",2020,"10.1029/2020JD033214","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094116196&doi=10.1029%2f2020JD033214&partnerID=40&md5=8e7d29c64f008bcc10fceaa5aad62678","A climatology of the marine atmospheric boundary layer (MABL) and the lower free troposphere over the Southern Ocean (SO) is constructed using 2,186 high-resolution atmospheric soundings from four recent campaigns conducted in the period of 2016–2018. Relationships between the synoptic meteorology and MABL thermodynamic structure are examined using a k-means cluster analysis, complemented by front and cyclone composite analyses. Seven distinct clusters are identified, five of which are consistent with an established climatology over the SO storm track. Two new clusters (C1 and C2) are introduced over the high-latitude SO. C1 is commonly located poleward of the ocean polar front near mesocyclones, while C2 is located along the Antarctic coastline. A multilayer cloud structure is frequently present in clusters in the vicinity of fronts and cyclones, while a single-layer coverage is more common in a suppressed environment, particularly at lower latitudes. A cloud-free, multilevel inversion is frequently observed in cluster C2, possibly linked to the descending, dry, katabatic winds off the Antarctic coast. A strong, primary inversion is typically present in clusters at lower latitudes with high mean sea level pressure. Across the SO storm track and higher latitudes (cluster C1), a multilevel inversion structure is also commonly observed. A preliminary analysis of two case studies suggests that upper level advection and detrainment of convection associated with mesocyclones are potential drivers of the multilayer cloud coverage over the high-latitude SO rather than the decoupling mechanisms common in the subtropics. ©2020. American Geophysical Union. All Rights Reserved."
"57206697543;35307051000;57209793755;26022467200;57210164917;34568423700;57197517376;57219428027;57210148415;13403849600;55314647100;7004165697;54797474600;13405658600;10046289000;","Hazardous Air Pollutants in Fresh and Aged Western US Wildfire Smoke and Implications for Long-Term Exposure",2020,"10.1021/acs.est.0c04497","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092680739&doi=10.1021%2facs.est.0c04497&partnerID=40&md5=452c03e483698066b88544d86a4997b2","Wildfires have a significant adverse impact on air quality in the United States (US). To understand the potential health impacts of wildfire smoke, many epidemiology studies rely on concentrations of fine particulate matter (PM) as a smoke tracer. However, there are many gas-phase hazardous air pollutants (HAPs) identified by the Environmental Protection Agency (EPA) that are also present in wildfire smoke plumes. Using observations from the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN), a 2018 aircraft-based field campaign that measured HAPs and PM in western US wildfire smoke plumes, we identify the relationships between HAPs and associated health risks, PM, and smoke age. We find the ratios between acute, chronic noncancer, and chronic cancer HAPs health risk and PM in smoke decrease as a function of smoke age by up to 72% from fresh (<1 day of aging) to old (>3 days of aging) smoke. We show that acrolein, formaldehyde, benzene, and hydrogen cyanide are the dominant contributors to gas-phase HAPs risk in smoke plumes. Finally, we use ratios of HAPs to PM along with annual average smoke-specific PM to estimate current and potential future smoke HAPs risks. Copyright © 2020 American Chemical Society."
"35619212800;36868795400;35228711600;7003408439;","Kelvin waves during GOAmazon and their relationship to deep convection",2020,"10.1175/JAS-D-20-0008.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094133091&doi=10.1175%2fJAS-D-20-0008.1&partnerID=40&md5=5c4319259340aaecb69395fa3a0fc17b","The 2014–15 Observations and Modeling of the Green Ocean Amazon (GOAmazon) field campaign over the central Amazon near Manaus, Brazil, occurred in coordination with the larger Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (CHUVA) project across Brazil. These programs provide observations of convection over the central Amazon on diurnal to annual time scales. In this study, we address the question of how Kelvin waves, observed in satellite observations of deep cloud cover over the GOAmazon region during the 2014–15 time period, modulate the growth, type, and organization of convection over the central Amazon. The answer to this question has implications for improved predictability of organized systems over the region and representation of convection and its growth on local to synoptic scales in global models. Our results demonstrate that Kelvin waves are strong modulators of synoptic-scale low- to midlevel free-tropospheric moisture, integrated moisture convergence, and surface heat fluxes. These regional modifications of the environment impact the local diurnal cycle of convection, favoring the development of mesoscale convective systems. As a result, localized rainfall is also strongly modulated, with the majority of rainfall in the GOAmazon region occurring during the passage of these systems. Ó 2020 American Meteorological Society."
"57077386600;34772240500;56162305900;57193213111;","Assessing CLUBB PDF Closure Assumptions for a Continental Shallow-to-Deep Convective Transition Case Over Multiple Spatial Scales",2020,"10.1029/2020MS002145","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094177329&doi=10.1029%2f2020MS002145&partnerID=40&md5=5e2a38e6b6a24d8d4e9391696e14b924","Assumed-PDF (probability density function) higher-order turbulence closures (APHOCs) are now widely used for parameterizing boundary layer turbulence and shallow convection in Earth system models (ESMs). A better understanding of the resolution-dependent behavior of APHOCs is essential for improving the performance of next-generation ESMs with intended horizontal resolutions finer than 10 km. In this study, we evaluate the PDF family of Analytic double-Gaussian 1 implemented in Cloud Layers Unified By Binormals (CLUBB) over a range of spatial scales (Dx) from 2 to 100 km. A 120-km-wide large eddy simulation (LES) for a continental convection case during 2016 Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) field campaign serves as benchmark to evaluate the PDF closure using an off-line approach. We find during the shallow convection period, the CLUBB PDF closure tends to produce positive biases of cloud properties and liquid water flux near cloud base for all scales of analysis. It produces negative biases for these variables near cloud top that are more severe for Dx larger than 25 km. Results show that replacing the CLUBB-parameterized moisture and temperature skewnesses with LES-derived ones can fix most of the biases if clipping of input moments is allowed to prevent the occurrence of unrealizable solutions. Overall, the performance of the PDF closure is better for smaller Dx = 2–5 km than for larger Dx = 50–100 km; for a given grid spacing, it is better when the convective clouds become deeper in the late afternoon. Likely causes for the resolution dependence and implications for improving the PDF closure are discussed. © 2020. The Authors."
"56003480700;6701590980;","LLAP band structure and intense lake-effect snowfall downwind of lake ontario: Insights from the OWLeS 7-9 january 2014 event",2020,"10.1175/JAMC-D-19-0288.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092940035&doi=10.1175%2fJAMC-D-19-0288.1&partnerID=40&md5=b6f08273a019fb638f2f3961389f04f6","Modeling and observational studies stemming from the 2013-14 Ontario Winter Lake-Effect Systems (OWLeS) field campaign have yielded much insight into the structure and development of long-lake-axis-parallel (LLAP) lake-effect systems over Lake Ontario. This study uses airborne single- and dual-Doppler radar data obtained during two University of Wyoming King Air flights, as well as a high-resolution numerical model simulation, to examine and contrast two distinctly different LLAP band structures observed within a highly persistent lake-effect system on 7-9 January 2014.On 7 January, a very cold airmass accompanied by strong westerly winds and weak capping aloft resulted in a deep, intense LLAP band that produced heavy snowfall well inland. In contrast, weaker winds, weaker surface heat fluxes, and stronger capping aloft resulted in a weaker LLAP band on 9 January. This band was blocked along the downwind shore and produced only light snowfall closer to the shoreline. Although the two structures examined here represent opposite ends of a spectrum of LLAP bands, both cases reveal a well-organizedmesoscale secondary circulation composed of two counterrotating horizontal vortices positioned on either side of a narrow updraft within the band. In both cases, this circulation traces back to a shallow, baroclinic land-breeze front originating along a bulge in the lake’s southern shoreline. As the band extends downstream and the low-level baroclinity weakens, buoyancy increases within the band-driven in part by cloud latent heating-leading to band intensification and a deeper, stronger, and more symmetric secondary circulation over the lake. © 2020 American Meteorological Society."
"24529012400;24474344900;","Daytime measurements of bioaerosol simulants using a hyperspectral laser-induced fluorescence LIDAR for biosphere research",2020,"10.1016/j.jece.2020.104392","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092698339&doi=10.1016%2fj.jece.2020.104392&partnerID=40&md5=60112483a926b4bd3c5212f81b9b5f5e","A new compact home-built hyper-spectral laser-induced fluorescence (LIF) light detection and ranging (LIDAR) system is presented that can detect and identify bioaerosol clouds in an open atmosphere in daylight up to a distance of 3-4 km. The system is based on a 266 nm laser source and a dual-stage micro-channel plate intensified charge-coupled device sensor, which provides a high-resolution fluorescence spectrum with the sensitivity of a single photon counting imaging detection at a 10 Hz repetition rate. Controlled remote sensing experiments on biological simulants in the aerosol-phase within an enclosed chamber (?R=1.2 m) were conducted from a short distance of ~170 m. A meticulous comparison between the remote fluorescence signal detected by the system and the instantaneous concentration and particle size distribution of the bioaerosol inside the chamber detected by an aerodynamic particle sizer yielded a threshold of ~20 and 137 µg r s m-3 for the spectral identification of tryptophan and ovalbumin, respectively. This showed that the LIDAR can measure environmental airborne biological aerosol remotely in the daytime and can be utilized as a real-time biosphere research tool. Next, the system was tested in open atmospheric field campaigns in the Israeli desert during the day. It successfully detected bioaerosol clouds at up to 2.5 km in strong wind and sunny conditions. These empirical detection and identification results provide robust estimates that a biological cloud can be sensed at a distance of ~4 km. © 2020 Elsevier Ltd."
"57188689884;57204253860;7102866124;","The amazonian low-level jet and its connection to convective cloud propagation and evolution",2020,"10.1175/MWR-D-19-0414.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092218317&doi=10.1175%2fMWR-D-19-0414.1&partnerID=40&md5=8584171c103690cbceadc4502297c0da","We describe the existence of an Amazonian low-level jet (ALLJ) that can affect the propagation and life cycle of convective systems from the northeast coast of South America into central Amazonia. Horizontal winds from reanalysis were analyzed during March-April-May (MAM) of the two years (2014-15) of the GoAmazon2014/5 field campaign. Convective system tracking was performed using GOES-13 infrared imagery and classified into days with high and weak convective activity. The MAM average winds show a nocturnal enhancement of low-level winds starting near the coast in the early evening and reaching 1600 km inland by late morning. Mean 3-hourly wind speeds maximize at 9-10ms21 near 900 hPa, but individual days can have nighttime low-level winds exceeding 12ms21. Based on objective low-level wind criteria, the ALLJ is present 10%-40% of the time over the Amazon during MAM depending on the location and time of day. The evolution of the ALLJ across the Amazon impacts the frequency of occurrence of cloud clusters and the intensity of the moisture flux. In addition, the ALLJ is associated with the enhancement of northeasterly flow in the midtroposphere during active convective days, when vertical momentum transport may be occurring in the organized cloud clusters. During the weakly active convective period, the ALLJ is weaker near the coast but stronger across the central Amazon and appears to be linked more directly with the South American low-level jet. © 2020 American Meteorological Society."
"36706881700;56797160600;57214404106;23020556600;56609369600;57190029731;55705571600;57218665240;","Radiation profiles from the surface up to the upper troposphere and lower stratosphere over the Tibetan Plateau",2020,"10.1088/1748-9326/abafd2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092028579&doi=10.1088%2f1748-9326%2fabafd2&partnerID=40&md5=bc640e619d87e7eb7d7016d155e4e490","Variations in solar shortwave and thermal longwave radiation over the Tibetan Plateau (TP) are crucial for global climate and regional ecological environment. Previous radiation studies over the TP were widely based on ground and satellite measurements of the radiation budget at the surface and at the top of the atmosphere. A stratospheric balloon-based radiation measurement system was employed in a 2019 field campaign to study how and why radiation profiles vary over the TP during the Asian summer monsoon (ASM) period. We originally provide in situ measurements of multiwavelength radiation profiles from the surface up to the upper troposphere and lower stratosphere (UTLS) over the TP. These valuable observations, combined with simultaneous operational radiosondes, ground measurements, satellite retrievals and radiative transfer model simulations, are used to study radiation variations and the radiative forcings of clouds and aerosols over the TP during the ASM period. Cloud occurrences beneath the balloon flight altitude induce more balloon-borne shortwave upward radiation and ultraviolet upward radiation but less longwave upward radiation relative to clear sky counterparts. The radiative transfer model simulations capture the variations in balloon shortwave downward radiation (SDR) profiles well. Cloud radiative forcings at the UTLS and surface vary greatly with varying cloud cover. The diurnal evolution of the SDR discrepancy between the balloon altitudes and surface and the aerosol radiative forcing at the bottom of the atmosphere are also discussed during the balloon flight periods. The results of this study are expected to improve our understanding of radiation properties in the UTLS and help us better comprehend the thermal conditions associated with clouds and aerosols over the TP during the ASM. © 2020 The Author(s). Published by IOP Publishing Ltd."
"57203052406;7003842561;57193063351;35396858200;16834406100;6603372665;","On the submicron aerosol distributions and CCN activity in and around the Korean Peninsula measured onboard the NASA DC-8 research aircraft during the KORUS-AQ field campaign",2020,"10.1016/j.atmosres.2020.105004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083726230&doi=10.1016%2fj.atmosres.2020.105004&partnerID=40&md5=6bff8dc42bf9eb4bd20cf8c49e551fc8","Aerosol and CCN number concentrations, and aerosol size distributions in and around the Korean Peninsula were measured onboard the NASA DC-8 research aircraft during the KORUS-AQ campaign in May and June of 2016. The average and standard deviation values of total aerosol number concentrations (diameter &gt; 10 nm, NCN10) in the boundary layer (below 1 km altitude) over Seoul, the Korean Peninsula, the Yellow Sea, the East Sea, and the South Sea were 12,318±7808, 10,721±8636, 7599±8583, 5759±6051, and 4186±4777 cm−3, respectively. Corresponding values for CCN number concentration at 0.6% supersaturation (NCCN06) were 3358±1916, 3613±2242, 3422±1707, 2313±1039, and 1819±1328 cm−3, respectively. NCN10 was highly variable according to region and period. In contrast, NCCN06 was relatively invariant regardless of region and period. With the PMF analysis on the aircraft measured aerosol size distribution and NCCN06 data, it was found that aerosol size distributions were composed of several distinct modes and they were different depending on regions. The aerosol hygroscopicity parameter κ was also estimated based on the PMF analysis results. The estimated κ values over Seoul, the Korean Peninsula, and the Yellow Sea were 0.11, 0.11, and 0.36, respectively. Lastly, the CCN closure experiments indicated that CCN concentration could be successfully estimated with the aerosol size distribution data and the estimated κ information from the aircraft measurements. Overall, it was demonstrated that PMF analysis technique could be applied to extract valuable information from limited aircraft measurement dataset. © 2020 Elsevier B.V."
"56341136800;15922221400;57192810488;55512674800;6603652793;7006561559;7202655072;7401776563;","Evaluation of Stratospheric Intrusions and Biomass Burning Plumes on the Vertical Distribution of Tropospheric Ozone Over the Midwestern United States",2020,"10.1029/2020JD032454","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091461098&doi=10.1029%2f2020JD032454&partnerID=40&md5=0f6e2fc2cf679ef8e6713160754ba67b","Naturally occurring ozone-rich stratosphere-to-troposphere transport (STT) intrusions and biomass burning (BB) plumes reaching the surface can contribute to exceedances of the U.S. National Ambient Air Quality Standards for ground-level ozone (70 ppbv implemented in 2015). Additionally, fires can inject significant pollution into the free troposphere where it can be transported long distances. The combined air quality impacts from these sources on ozone have only been analyzed in a few case studies for the Midwest United States. Here we study ozone impacts in a Midwestern city, for the first time in St. Louis, Missouri, using a series of ozonesonde profiles taken during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign in August–September 2013. All ozonesondes showed enhancements above the background profile levels (~55 ppbv) throughout each tropospheric column. Two models were used to estimate ozone origins in columns. A chemical transport model identified STT enhancements equivalent to 10 to 15 ppbv over the background with a 10% to 15% contribution overall to the column. Two FLEXPART-WRF simulations, one with smoke in the boundary layer and another with smoke above, identified BB enhancements equivalent to 10 to 80 ppbv. Overall, the total BB contribution is 15% to 30% of the total column. Five ozonesondes showed signatures of mixed BB plumes and STT intrusions. During this study period, BB in the western United States contributed 70% to ozone enhancements in the total column compared to 3% from the central United States and 27% from other areas. ©2020. American Geophysical Union. All Rights Reserved."
"8966521400;56414846700;7003512900;6603599576;57219343824;13310389200;","Aerosol data assimilation in the MOCAGE chemical transport model during the TRAQA/ChArMEx campaign: Lidar observations",2020,"10.5194/amt-13-4645-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092301800&doi=10.5194%2famt-13-4645-2020&partnerID=40&md5=e3fae04030cac0585031786e531ea86d","This paper presents the first results about the assimilation of CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) extinction coefficient measurements onboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite in the MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) chemistry transport model of Météo-France. This assimilation module is an extension of the aerosol optical depth (AOD) assimilation system already presented by Sic et al.? (2016). We focus on the period of the TRAQA (TRAnsport à longue distance et Qualité de l'Air dans le bassin méditerranéen) field campaign that took place during summer 2012. This period offers the opportunity to have access to a large set of aerosol observations from instrumented aircraft, balloons, satellite and ground-based stations. We evaluate the added value of CALIOP assimilation with respect to the model free run by comparing both fields to independent observations issued from the TRAQA field campaign. In this study we focus on the desert dust outbreak which happened during late June 2012 over the Mediterranean Basin (MB) during the TRAQA campaign. The comparison with the AERONET (Aerosol Robotic Network) AOD measurements shows that the assimilation of CALIOP lidar observations improves the statistics compared to the model free run. The correlation between AERONET and the model (assimilation) is 0.682 (0.753); the bias and the root mean square error (RMSE), due to CALIOP assimilation, are reduced from-0.063 to 0.048 and from 0.183 to 0.148, respectively. Compared to MODIS (Moderate-resolution Imaging Spectroradiometer) AOD observations, the model free run shows an underestimation of the AOD values, whereas the CALIOP assimilation corrects this underestimation and shows a quantitative good improvement in terms of AOD maps over the MB. The correlation between MODIS and the model (assimilation) during the dust outbreak is 0.47 (0.52), whereas the bias is-0.18 (-0.02) and the RMSE is 0.36 (0.30). The comparison of in situ aircraft and balloon measurements to both modelled and assimilated outputs shows that the CALIOP lidar assimilation highly improves the model aerosol field. The evaluation with the LOAC (Light Optical Particle Counter) measurements indicates that the aerosol vertical profiles are well simulated by the direct model but with a general underestimation of the aerosol number concentration, especially in the altitude range 2-5 km. The CALIOP assimilation improves these results by a factor of 2.5 to 5. Analysis of the vertical distribution of the desert aerosol concentration shows that the aerosol dust transport event is well captured by the model but with an underestimated intensity. The assimilation of CALIOP observations allows the improvement of the geographical representation of the event within the model as well as its intensity by a factor of 2 in the altitude range 1-5 km. © 2020 Author(s)."
"57209100678;57219297551;56452764100;7202105179;57211693829;56957931600;26421520600;6603315336;23985897000;","Evaluating post-fire vegetation recovery in Cajander Larch Forests in Northeastern Siberia using UAV derived vegetation indices",2020,"10.3390/RS12182970","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092115750&doi=10.3390%2fRS12182970&partnerID=40&md5=d54d48c364074d30e2896cd6a8316e2b","The ability to monitor post-fire ecological responses and associated vegetation cover change is crucial to understanding how boreal forests respond to wildfire under changing climate conditions. Uncrewed aerial vehicles (UAVs) offer an affordable means of monitoring post-fire vegetation recovery for boreal ecosystems where field campaigns are spatially limited, and available satellite data are reduced by short growing seasons and frequent cloud cover. UAV data could be particularly useful across data-limited regions like the Cajander larch (Larix cajanderi Mayr.) forests of northeastern Siberia that are susceptible to amplified climate warming. Cajander larch forests require fire for regeneration but are also slow to accumulate biomass post-fire; thus, tall shrubs and other understory vegetation including grasses, mosses, and lichens dominate for several decades post-fire. Here we aim to evaluate the ability of two vegetation indices, one based on the visible spectrum (GCC; Green Chromatic Coordinate) and one using multispectral data (NDVI; Normalized Difference Vegetation Index), to predict field-based vegetation measures collected across post-fire landscapes of high-latitude Cajander larch forests. GCC and NDVI showed stronger linkages with each other at coarser spatial resolutions e.g., pixel aggregated means with 3-m, 5-m and 10-m radii compared to finer resolutions (e.g., 1-m or less). NDVI was a stronger predictor of aboveground carbon biomass and tree basal area than GCC. NDVI showed a stronger decline with increasing distance from the unburned edge into the burned forest. Our results show NDVI tended to be a stronger predictor of some field-based measures and while GCC showed similar relationships with the data, it was generally a weaker predictor of field-based measures for this region. Our findings show distinguishable edge effects and differentiation between burned and unburned forests several decades post-fire, which corresponds to the relatively slow accumulation of biomass for this ecosystem post-fire. These findings show the utility of UAV data for NDVI in this region as a tool for quantifying and monitoring the post-fire vegetation dynamics in Cajander larch forests. © 2020 by the authors."
"55271827000;57193213111;8922308700;7006643234;56488136100;57218291394;7003570692;","Simulation of Continental Shallow Cumulus Populations Using an Observation-Constrained Cloud-System Resolving Model",2020,"10.1029/2020MS002091","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091633428&doi=10.1029%2f2020MS002091&partnerID=40&md5=c763ade03602c61875afe5a2f81649a0","Continental shallow cumulus (ShCu) clouds observed on 30 August 2016 during the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) field campaign are simulated by using an observation-constrained cloud-system resolving model. On this day, ShCu forms over Oklahoma and southern Kansas and some of these clouds transition to deeper, precipitating convection during the afternoon. We apply a four-dimensional ensemble-variational (4DEnVar) hybrid technique in the Community Gridpoint Statistical Interpolation (GSI) system to assimilate operational data sets and unique boundary layer measurements including a Raman lidar, radar wind profilers, radiosondes, and surface stations collected by the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) atmospheric observatory into the Weather Research and Forecasting (WRF) model to ascertain how improved environmental conditions can influence forecasts of ShCu populations and the transition to deeper convection. Independent observations from aircraft, satellite, as well as ARM's remote sensors are used to evaluate model performance in different aspects. Several model experiments are conducted to identify the impact of data assimilation (DA) on the prediction of clouds evolution. The analyses indicate that ShCu populations are more accurately reproduced after DA in terms of cloud initiation time and cloud base height, which can be attributed to an improved representation of the ambient meteorological conditions and the convective boundary layer. Extending the assimilation to 18 UTC (local noon) also improved the simulation of shallow-to-deep transitions of convective clouds. © 2020. The Authors."
"56829579700;55740664200;56829592600;57198616562;57192073812;","Radiative heating rate profiles over the southeast Atlantic Ocean during the 2016 and 2017 biomass burning seasons",2020,"10.5194/acp-20-10073-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091756139&doi=10.5194%2facp-20-10073-2020&partnerID=40&md5=cf4c2414ae859cb47a87cf9545e97bdc","Marine boundary layer clouds, including the transition from stratocumulus to cumulus, are poorly represented in numerical weather prediction and general circulation models. Further uncertainties in the cloud structure arise in the presence of biomass burning carbonaceous aerosol, as is the case over the southeast Atlantic Ocean, where biomass burning aerosol is transported from the African continent. As the aerosol plume progresses across the southeast Atlantic Ocean, radiative heating within the aerosol layer has the potential to alter the thermodynamic environment and therefore the cloud structure; however, limited work has been done to quantify this along the trajectory of the aerosol plume in the region. The deployment of the first Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF1) in support of the Layered Atlantic Smoke Interactions with Clouds field campaign provided a unique opportunity to collect observations of cloud and aerosol properties during two consecutive biomass burning seasons during July through October of 2016 and 2017 over Ascension Island (7.96- S, 14.35- W). Using observed profiles of temperature, humidity, and clouds from the field campaign alongside aerosol optical properties from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), as input for the Rapid Radiation Transfer Model (RRTM), profiles of the radiative heating rate due to aerosols and clouds were computed. Radiative heating is also assessed across the southeast Atlantic Ocean using an ensemble of back trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Idealized experiments using the RRTM with and without aerosols and a range of values for the single-scattering albedo (SSA) demonstrate that shortwave (SW) heating within the aerosol layer above Ascension Island can locally range between 2 and 8Kd-1 depending on the aerosol optical properties, though impacts of the aerosol can be felt elsewhere in the atmospheric column. When considered under clear conditions, the aerosol has a cooling effect at the TOA, and based on the observed cloud properties at Ascension Island, the cloud albedo is not large enough to overcome this. Shortwave radiative heating due to biomass burning aerosol is not balanced by additional longwave (LW) cooling, and the net radiative impact results in a stabilization of the lower troposphere. However, these results are extremely sensitive to the single-scattering albedo assumptions in models.. © 2020 Laser Institute of America. All rights reserved."
"56763058500;56349358200;56349223500;37105039700;57210152063;57218517417;7201920350;7401796996;8629713500;55352172500;57199068971;56923937200;","Spatial Distribution and Impacts of Aerosols on Clouds Under Meiyu Frontal Weather Background Over Central China Based on Aircraft Observations",2020,"10.1029/2019JD031915","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089363716&doi=10.1029%2f2019JD031915&partnerID=40&md5=e6ccdc5bee8ad5187b3958e7033d53cc","An airborne field campaign was conducted from 10 June to 10 July 2018 in Hubei Province over central China as a part of the State Key Natural Science Foundation Project referred to as Integrative Monsoon Frontal Rainfall Experiment (IMFRE). Comprehensive observations of atmospheric aerosols and cloud characteristics in this region were collected and analyzed. In this study, data from six flights on nonprecipitating days were selected to investigate the spatial distribution of aerosols and microphysical properties of clouds. The profiles of aerosol number concentrations (Na) were 1 order of magnitude lower than those over the North Plain of China, due to the different atmospheric backgrounds, local emission, and long-range transport. The highest Na occurred at the altitude of the temperature inversion layer (TIL), indicating that Na profiles were significantly affected by the TIL structure. Relative humidity (RH) had an effect on the aerosol size distribution where high RH values corresponded well with large values of particle mean diameter (MD). Compared with the vertical distributions of Na and MD, their horizontal directions had minor changes, except for the MD at 4,000 m in one case. Of the three flights that penetrated through the stratiform clouds, the probability distribution functions of cloud droplet number concentration (Nc), effective radius (re), and liquid water content (LWC), showed the same features with a single peak mode. Since the nucleation of aerosol in-cloud caused the decrease of aerosol concentration, the maximum aerosol activation ratio almost reached 74%. The average spectrum of cloud droplets showed a multimodal distribution and their microphysical properties were analyzed in this study. ©2020. American Geophysical Union. All Rights Reserved."
"57199999083;24460392200;57218650638;35101612400;56100447800;57193214312;57203123858;","Synergistic radar and radiometer retrievals of ice hydrometeors",2020,"10.5194/amt-13-4219-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089906354&doi=10.5194%2famt-13-4219-2020&partnerID=40&md5=ab95e2763a0fae0ef336094fe4782bd7","Remote sensing observations at sub-millimeter wavelengths provide higher sensitivity to small hydrometeors and low water content than observations at millimeter wavelengths, which are traditionally used to observe clouds and precipitation. They are employed increasingly in field campaigns to study cloud microphysics and will be integrated into the global meteorological observing system to measure the global distribution of ice in the atmosphere with the launch of the Ice Cloud Imager (ICI) radiometer on board the second generation of European operational meteorological satellites (Metop-SG). Observations at these novel wavelengths provide valuable information not only on their own but also in combination with complementary observations at other wavelengths. This study investigates the potential of combining passive sub-millimeter radiometer observations with a hypothetical W-band cloud radar for the retrieval of frozen hydrometeors. An idealized cloud model is used to investigate the information content of the combined observations and establish their capacity to constrain the microphysical properties of ice hydrometeors. A synergistic retrieval algorithm for airborne observations is proposed and applied to simulated observations from a cloud-resolving model. Results from the synergistic retrieval are compared to equivalent radar- and passive-only implementations in order to assess the benefits of the synergistic sensor configuration. The impact of the assumed ice particle shape on the retrieval results is assessed for all retrieval implementations. We find that the combined observations better constrain the microphysical properties of ice hydrometeors, which reduces uncertainties in retrieved ice water content and particle number concentrations for suitable choices of the ice particle model. Analysis of the retrieval information content shows that, although the radar contributes the largest part of the information in the combined retrieval, the radiometer observations provide complementary information over a wide range of atmospheric states. Furthermore, the combined observations yield slightly improved retrievals of liquid cloud water in mixed-phase clouds, pointing towards another potential application of combined radar-radiometer observations. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License."
"36183647300;7402064802;14019399400;56479980800;57193933577;36856321600;6506848305;8859530100;6701592014;","Assessment of precipitating marine stratocumulus clouds in the E3SMv1 atmosphere model: A case study from the ARM MAGIC field campaign",2020,"10.1175/MWR-D-19-0349.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091853505&doi=10.1175%2fMWR-D-19-0349.1&partnerID=40&md5=a0bf50876e64e9fc18774c538a884a58","This paper presents a process-oriented evaluation of precipitating stratocumulus and its transition to cumulus in version 1 of the Energy Exascale Earth System Model (E3SMv1) using comprehensive case-study observations from a field campaign of the Atmospheric Radiation Measurement program (ARM). The E3SMv1 single-column model (SCM) of the marine boundary layer and its low clouds and precipitation are compared to observations including subcloud drizzle retrievals from a combination of Doppler radar and lidar backscatter measurements. The SCM is also compared to a large-eddy simulation (LES) of the same case. The combination of advanced remote sensing observations and LES is a powerful framework to evaluate the physical parameterizations of large-scale models. Given the observed large-scale environment, the E3SMv1 SCM realistically represents the evolution of clouds and boundary layer structure during the stratocumulus-to-cumulus transition. The model well simulates the liquid water path and its diurnal cycle in the stratocumulus period as well as the two-layer vertical thermodynamic structure and lower cloud fraction in the transition period. E3SMv1's success in simulating the cloud in the stratocumulus period permitted examination of its precipitation processes. Here problems were identified with E3SMv1 producing an unrealistically small subcloud precipitation fraction, an unrealistic double peak in the vertical profiles of precipitation mass, and drizzle that evaporates too close to the surface. Further model diagnostics determined that these unrealistic characteristics resulted from an overly long microphysics time step and an unrealistic parameterization of the precipitation fraction. These results imply that careful consideration of these issues is needed in order to better simulate precipitation processes in marine stratocumulus. © 2020 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses)."
"25924727700;","A New Lens for Evaluating Dynamic Controls on Shallow Convection",2020,"10.1029/2020MS002249","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089838537&doi=10.1029%2f2020MS002249&partnerID=40&md5=819a1a9cac5698780f2461da4851faab","Rising temperatures and changing dynamics can both moisten the air, making it difficult to disentangle these interrelated drivers of water cycle change. However, work by Camille Risi and colleagues presents a new way to distinguish their effects. Using large-eddy simulations with water isotopic tracers, they show that while warming the sea surface increases the ratio of isotopically heavy-to-light water in the tropical marine subcloud layer, strengthening the moisture flux convergence decreases it. This divergent response provides a new framework for examining the complex mechanisms that regulate the development of convection and, ultimately, cloudiness—a target of the 2020 international field campaign EUREC4A (ElUcidating the RolE of Clouds-Circulation Coupling in ClimAte). Moreover, their findings provide a clearer picture of why water isotopes recorded in tropical paleoproxies are a valuable lens through which to view changes in moisture transport in the past. © 2020. The Authors."
"57195056873;7201920350;35209683700;56923937200;57202925605;57199068971;57217862195;57217857005;57208383202;57217862422;7401796996;","Localization and Invigoration of Mei-yu Front Rainfall due to Aerosol-Cloud Interactions: A Preliminary Assessment Based on WRF Simulations and IMFRE 2018 Field Observations",2020,"10.1029/2019JD031952","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087728434&doi=10.1029%2f2019JD031952&partnerID=40&md5=721532e2765cf0e7a2ccfe36488c62be","Aerosol-cloud interactions remain a major source of uncertainty in our understanding and modeling of the Earth's hydrological cycle. Based upon a diagnostic and modeling analysis utilizing the latest field measurements from the Integrative Monsoon Frontal Rainfall Experiment (IMFRE) 2018, this paper reports the effects of aerosols on the cloud properties along the Mei-yu front over the Middle Reaches of Yangtze River in China. Numerical experiments with the Weather Research and Forecasting (WRF) model suggest that increasing aerosol number concentration reduces surface precipitation by ~8.8% and delays the onset of rainfall by ~30 min. Furthermore, warm clouds are suppressed but the convective cores are slightly intensified. This corresponds to an overall aerosol effect of “localization and invigoration” of the Mei-yu rainfall and thus an elevated probability of short-term heavy rainfall. The signals of “convective invigoration” with a bulk scheme in this study are relatively weak compared to those simulated by bin microphysics. The increased aerosol concentration strengthens Mei-yu front and changes local morphology of the front, consistent with earlier studies demonstrating positive effects of convective heating on the genesis and maintenance of Mei-yu front via conditional instability of the second kind (CISK) and diabatic generation of potential vorticity. Also discussed are the uncertainties of bulk microphysics in simulating aerosol-cloud interactions, which may shed light on the design of future field campaigns to further understand the impact of aerosol-cloud interactions on weather and climate over China in boreal summer. ©2020. American Geophysical Union. All Rights Reserved."
"57213002882;55984424900;7005601996;6603093035;55943979800;13204951000;57092684000;7005461772;7003993113;8657171200;10739566100;7006708207;57217853456;57189377456;21834810800;","Linking Marine Biological Activity to Aerosol Chemical Composition and Cloud-Relevant Properties Over the North Atlantic Ocean",2020,"10.1029/2019JD032246","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087705734&doi=10.1029%2f2019JD032246&partnerID=40&md5=c5e6f464ee4b1c1efc425d4c46bcbfba","The ways in which marine biological activity affects climate, by modifying aerosol properties, are not completely understood, causing high uncertainties in climate predictions. In this work, in situ measurements of aerosol chemical composition, particle number size distribution, cloud condensation nuclei (CCN), and ice-nucleating particle (INP) number concentrations are combined with high-resolution sea surface chlorophyll-a concentration (CHL) and back-trajectory data to elucidate the relationship between oceanic biological activity and marine aerosol. The measurements were performed during an intensive field campaign conducted in late summer (August–September) 2015 at the Mace Head Research Station (MHD). At the short time scale (1–2 months) of the experiment, we observed a clear dependency of the main aerosol physicochemical and cloud-relevant properties on the patterns of biological activity, in specific oceanic regions with a delayed response of about 1–3 weeks. The oceanic region comprised between 47°–57°N and 14°–30°W was identified as the main source of biogenic aerosols during the campaign, with hints of some minor influence of waters up to the Greenland coast. These spatial and temporal relationships demonstrate that the marine biota influences aerosol properties under a variety of features up to the most cloud-relevant properties. Such dependency of aerosol properties with oceanic biological activity was previously reported over the North Atlantic Ocean only for multiyear data sets, where the correlation may be enhanced by coincident seasonalities. A better knowledge of these short time scale interactions may lead to a significant improvement in understanding the ocean-atmosphere-cloud system, with important impacts on climate science. ©2020. American Geophysical Union. All Rights Reserved."
"11142241900;17341189400;37162122100;56166035200;35771409400;55339747900;55403093700;54906850600;7004200774;6505905181;","A new optical-based technique for real-time measurements of mineral dust concentration in PM10 using a virtual impactor",2020,"10.5194/amt-13-3799-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088564864&doi=10.5194%2famt-13-3799-2020&partnerID=40&md5=796c08258594ca03255086cefd13f334","Atmospheric mineral dust influences Earth s radiative budget, cloud formation, and lifetime; has adverse health effects; and affects air quality through the increase of regulatory PM10 concentrations, making its real-time quantification in the atmosphere of strategic importance. Only few near-real-time techniques can discriminate dust aerosol in PM10 samples and they are based on the dust chemical composition. The online determination of mineral dust using aerosol absorption photometers offers an interesting and competitive alternative but remains a difficult task to achieve. This is particularly challenging when dust is mixed with black carbon, which features a much higher mass absorption cross section. We build on previous work using filter photometers and present here for the first time a highly timeresolved online technique for quantification of mineral dust concentration by coupling a high-flow virtual impactor (VI) sampler that concentrates coarse particles with an aerosol absorption photometer (Aethalometer, model AE33). The absorption of concentrated dust particles is obtained by subtracting the absorption of the submicron (PM1) aerosol fraction from the absorption of the virtual impactor sample (VIPM1 method). This real-time method for detecting desert dust was tested in the field for a period of 2 months (April and May 2016) at a regional background site of Cyprus, in the Eastern Mediterranean. Several intense desert mineral dust events were observed during the field campaign with dust concentration in PM10 up to 45 ?gm3. Mineral dust was present most of the time during the campaign with an average PM10 of about 8 ?gm3. Mineral dust absorption was most prominent at short wavelengths, yielding an average mass absorption cross section (MAC) of 0:24_0:01m2 g1 at 370 nm and an absorption ngstr m exponent of 1:41_0:29. This MAC value can be used as a site-specific parameter for online determination of mineral dust concentration. The uncertainty of the proposed method is discussed by comparing and validating it with different methods. © 2020 American Society of Civil Engineers (ASCE). All rights reserved."
"6602660916;55223107200;57201375640;54966735900;36651784500;57214571352;55040381200;36242420700;8697043300;","Post-earthquake recovery phase monitoring and mapping based on UAS data",2020,"10.3390/ijgi9070447","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089903314&doi=10.3390%2fijgi9070447&partnerID=40&md5=63efb4a39545465f21453198cbdeb5f7","Geoinformatics plays an essential role during the recovery phase of a post-earthquake situation. The aim of this paper is to present the methodology followed and the results obtained by the utilization of Unmanned Aircraft Systems (UASs) 4K-video footage processing and the automation of geo-information methods targeted at both monitoring the demolition process and mapping the demolished buildings. The field campaigns took place on the traditional settlement of Vrisa (Lesvos, Greece), which was heavily damaged by a strong earthquake (Mw=6.3) on June 12th, 2017. For this purpose, a flight campaign took place on 3rd February 2019 for collecting aerial 4K video footage using an Unmanned Aircraft. The Structure from Motion (SfM) method was applied on frames which derived from the 4K video footage, for producing accurate and very detailed 3D point clouds, as well as the Digital Surface Model (DSM) of the building stock of the Vrisa traditional settlement, twenty months after the earthquake. This dataset has been compared with the corresponding one which derived from 25th July 2017, a few days after the earthquake. Two algorithms have been developed for detecting the demolished buildings of the affected area, based on the DSMs and 3D point clouds, correspondingly. The results obtained have been tested through field studies and demonstrate that this methodology is feasible and effective in building demolition detection, giving very accurate results (97%) and, in parallel, is easily applicable and suit well for rapid demolition mapping during the recovery phase of a post-earthquake scenario. The significant advantage of the proposed methodology is its ability to provide reliable results in a very low cost and time-efficient way and to serve all stakeholders and national and local organizations that are responsible for post-earthquake management. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)."
"57193788172;57209398568;57206924573;6506051565;7004171611;36622868000;55914904100;55466977400;7102689523;57217728673;8525147900;","Cirrus cloud identification from airborne far-infrared and mid-infrared spectra",2020,"10.3390/rs12132097","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087543275&doi=10.3390%2frs12132097&partnerID=40&md5=676968cfa40c35c7e83f55bda62a3c94","Airborne interferometric data, obtained from the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) and from the PiknMix-F field campaign, are used to test the ability of a machine learning cloud identification and classification algorithm (CIC). Data comprise a set of spectral radiances measured by the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) and the Airborne Research Interferometer Evaluation System (ARIES). Co-located measurements of the two sensors allow observations of the upwelling radiance for clear and cloudy conditions across the far-and mid-infrared part of the spectrum. Theoretical sensitivity studies show that the performance of the CIC algorithm improves with cloud altitude. These tests also suggest that, for conditions encompassing those sampled by the flight campaigns, the additional information contained within the far-infrared improves the algorithm's performance compared to using mid-infrared data only. When the CIC is applied to the airborne radiance measurements, the classification performance of the algorithm is very high. However, in this case, the limited temporal and spatial variability in the measured spectra results in a less obvious advantage being apparent when using both mid-and far-infrared radiances compared to using mid-infrared information only. These results suggest that the CIC algorithm will be a useful addition to existing cloud classification tools but that further analyses of nadir radiance observations spanning the infrared and sampling a wider range of atmospheric and cloud conditions are required to fully probe its capabilities. This will be realised with the launch of the Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission, ESA's 9th Earth Explorer. © 2020 by the authors. Licensee MDPI, Basel, Switzerland."
"57218998453;57219001530;55911904900;6602137800;57126848900;7003444634;22635999400;56767841200;","Low-level liquid cloud properties during ORACLES retrieved using airborne polarimetric measurements and a neural network algorithm",2020,"10.5194/amt-13-3447-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090969618&doi=10.5194%2famt-13-3447-2020&partnerID=40&md5=f09f19453fedc386c06a10cc59bf5d55","In this study we developed a neural network (NN) that can be used to retrieve cloud microphysical properties from multiangular and multispectral polarimetric remote sensing observations. This effort builds upon our previous work, which explored the sensitivity of neural network input, architecture, and other design requirements for this type of remote sensing problem. In particular this work introduces a framework for appropriately weighting total and polarized reflectances, which have vastly different magnitudes and measurement uncertainties. The NN is trained using an artificial training set and applied to research scanning polarimeter (RSP) data obtained during the ORACLES field campaign (ObseRvations of Aerosols above CLouds and their intEractionS). The polarimetric RSP observations are unique in that they observe the same cloud from a very large number of angles within a variety of spectral bands, resulting in a large dataset that can be explored rapidly with a NN approach. The usefulness of applying a NN to a dataset such as this one stems from the possibility of rapidly obtaining a retrieval that could be subsequently applied as a first guess for slower but more rigorous physical-based retrieval algorithms. This approach could be particularly advantageous for more complicated atmospheric retrievals such as when an aerosol layer lies above clouds like in ORACLES. For RSP observations obtained during ORACLES 2016, comparisons between the NN and standard parametric polarimetric (PP) cloud retrieval give reasonable results for droplet effective radius (re: R D 0:756, RMSE D 1:74um) and cloud optical thickness ( R D 0:950, RMSE D 1:82). This level of statistical agreement is shown to be similar to comparisons between the two most well-established cloud retrievals, namely, the polarimetric and the bispectral total reflectance cloud retrievals. The NN retrievals from the ORACLES 2017 dataset result in retrievals of re (R D 0:54, RMSE D 4:77um) and (R D 0:785, RMSE D 5:61) that behave much more poorly. In particular we found that our NN retrieval approach does not perform well for thin ( < 3), inhomogeneous, or broken clouds. We also found that correction for above-cloud atmospheric absorption improved the NN retrievals moderately but retrievals without this correction still behaved similarly to existing cloud retrievals with a slight systematic offset. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License."
"54787703600;24492458800;15765075000;15765075000;","Improving sub-canopy snow depth mapping with unmanned aerial vehicles: Lidar versus structure-from-motion techniques",2020,"10.5194/tc-14-1919-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087209776&doi=10.5194%2ftc-14-1919-2020&partnerID=40&md5=bf425e4be05440f4ee847097c3c71197","Vegetation has a tremendous influence on snow processes and snowpack dynamics, yet remote sensing techniques to resolve the spatial variability of sub-canopy snow depth are not always available and are difficult from spacebased platforms. Unmanned aerial vehicles (UAVs) have had recent widespread application to capture high-resolution information on snow processes and are herein applied to the sub-canopy snow depth challenge. Previous demonstrations of snow depth mapping with UAV structure from motion (SfM) and airborne lidar have focussed on non-vegetated surfaces or reported large errors in the presence of vegetation. In contrast, UAV-lidar systems have high-density point clouds and measure returns from a wide range of scan angles, increasing the likelihood of successfully sensing the subcanopy snow depth. The effectiveness of UAV lidar and UAV SfM in mapping snow depth in both open and forested terrain was tested in a 2019 field campaign at the Canadian Rockies Hydrological Observatory, Alberta, and at Canadian prairie sites near Saskatoon, Saskatchewan, Canada. Only UAV lidar could successfully measure the sub-canopy snow surface with reliable sub-canopy point coverage and consistent error metrics (root mean square error (RMSE) <0:17 m and bias-0:03 to-0:13 m). Relative to UAV lidar, UAV SfM did not consistently sense the sub-canopy snow surface, the interpolation needed to account for point cloud gaps introduced interpolation artefacts, and error metrics demonstrated relatively large variability (RMSE<0:33 m and bias 0.08 to-0:14 m). With the demonstration of sub-canopy snow depth mapping capabilities, a number of early applications are presented to showcase the ability of UAV lidar to effectively quantify the many multiscale snow processes defining snowpack dynamics in mountain and prairie environments. © 2020 Author(s)."
"25626899800;57173256600;57204701883;23006506400;6507343798;9237551900;57209465284;13407676600;8550791300;57204497907;57191370661;57210592594;57218570101;57204700515;55998553400;55240548200;6602237750;36705265400;22837162400;49964118900;57204211678;24334476700;6602739185;53464001600;57003839000;56206316400;57206962716;57218564508;57103196700;56411079900;23008497400;15842432600;57191362166;55573988000;57218567661;57218564984;57218564428;6603289677;6506940151;6602143237;7005668444;7003268048;7203052598;7006415284;7402177459;","Marine organic matter in the remote environment of the Cape Verde islands-an introduction and overview to the MarParCloud campaign",2020,"10.5194/acp-20-6921-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089604858&doi=10.5194%2facp-20-6921-2020&partnerID=40&md5=a81e3498d53c763a6d54d4d8791c5039","The project MarParCloud (Marine biological production, organic aerosol Particles and marine Clouds: a process chain) aims to improve our understanding of the genesis, modification and impact of marine organic matter (OM) from its biological production, to its export to marine aerosol particles and, finally, to its ability to act as ice-nucleating particles (INPs) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atmospheric Observatory (CVAO) in the tropics in September-October 2017 formed the core of this project that was jointly performed with the project MARSU (MARine atmospheric Science Unravelled). A suite of chemical, physical, biological and meteorological techniques was applied, and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground-based and a mountain station took place. Key variables comprised the chemical characterization of the atmospherically relevant OM components in the ocean and the atmosphere as well as measurements of INPs and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analyzed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back-trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modeling studies supported the experimental analysis. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle number size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concentrations of marine background conditions. Accumulation-and coarse-mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean-derived compounds, such as sea salt and sugar-like compounds, to the cloud level, as derived from chemical analysis and atmospheric transfer modeling results, denotes an influence of marine emissions on cloud formation. Organic nitrogen compounds (free amino acids) were enriched by several orders of magnitude in submicron aerosol particles and in cloud water compared to seawater. However, INP measurements also indicated a significant contribution of other non-marine sources to the local INP concentration, as (biologically active) INPs were mainly present in supermicron aerosol particles that are not suggested to undergo strong enrichment during ocean-atmosphere transfer. In addition, the number of CCN at the supersaturation of 0.30 % was about 2.5 times higher during dust periods compared to marine periods. Lipids, sugar-like compounds, UV-absorbing (UV: ultraviolet) humic-like substances and low-molecularweight neutral components were important organic compounds in the seawater, and highly surface-active lipids were enriched within the SML. The selective enrichment of specific organic compounds in the SML needs to be studied in further detail and implemented in an OM source function for emission modeling to better understand transfer patterns, the mechanisms of marine OM transformation in the atmosphere and the role of additional sources. In summary, when looking at particulate mass, we see oceanic compounds transferred to the atmospheric aerosol and to the cloud level, while from a perspective of particle number concentrations, sea spray aerosol (i.e., primary marine aerosol) contributions to both CCN and INPs are rather limited. © Author(s) 2020."
"57212452751;56212055700;35621058500;","Remote sensing of two exceptional winter aerosol pollution events and representativeness of ground-based measurements",2020,"10.5194/acp-20-6749-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086722342&doi=10.5194%2facp-20-6749-2020&partnerID=40&md5=bf47fc7b7ad50ba7f56aed56b1d7c2cc","Two intense winter aerosol pollution events, which took place in winter 2016 2017 in Paris, were monitored using a ground-based N2-Raman lidar, in the framework of WASLIP (Winter Aerosol Survey by Lidar In Paris), a dedicated field campaign that was carried out in this area from 1 November 2016 to 31 January 2017. The data analysis uses the synergy between ground-based and spaceborne lidar observations and data from the air quality monitoring network Airparif. The first severe aerosol pollution event began on 30 November 2016 and ended on 2 December, concerning a circular area of ∼ 250 km in diameter around Paris. The maximum PM10 was 121 ± 63 μgm-3 (regional spatial average ± SD) for the Airparif ground-based PM monitoring stations, and the aerosol extinction coefficient (AEC) ranged from 0.2 to 1 km-1. The second event took place from 20 to 23 January which covered all of the northwestern Europe, with maxima of PM10 around 156±33 μgm-3 and AEC between 0.6 and 1 km-1, within the winter atmospheric boundary layer. Although these two major aerosol pollution events did not occur under identical anticyclonic weather conditions, they share very low planetary boundary layer (PBL) heights, down to 300 m above ground level. Moreover, they are associated with significantly different aerosol lidar ratios: 72 ± 15 and 56 ± 15 sr, respectively in December and January. Such results are consistent with available spaceborne lidar data, 70 ± 25 sr from CALIOP (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations), and values found in the literature. During these two events, the continuous temporal evolution of the aerosol extinction coefficient allows us to investigate the representativeness of optical parameters found in the planetary boundary layer to assess surface aerosol concentration. No one-to-one relationship between the aerosol optical thickness (AOT) and PM2:5 values stands out within our study. In contrast, the maximum aerosol extinction coefficient found within the planetary boundary layer correlates well with PM2:5 at the ground (R2 ∼ 0:75, specific extinction cross section of 9.4 m2 g-1/ for these polluted events. Thus this lidar-derived aerosol extinction coefficient is identified as a consistent variable to monitor the pollution during winter events. © 2020 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License."
"46461636700;46461636700;57212574325;57190947670;7004027519;57196968859;7006341827;57189333618;57217211899;57189442478;56732727200;8720897100;8871497700;15923105200;","Condensation/immersion mode ice-nucleating particles in a boreal environment",2020,"10.5194/acp-20-6687-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086762467&doi=10.5194%2facp-20-6687-2020&partnerID=40&md5=cc1b85787dd2f5569c48ff4abdd99922","<p>Ice-nucleating particle (INP) measurements were performed in the boreal environment of southern Finland at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II) in the winter-spring of 2018. Measurements with the Portable Ice Nucleation Chamber (PINC) were conducted at 242 <span classCombining double low line""inline-formula"">K</span> and 105 % relative humidity with respect to water. The median INP number concentration [INP] during a 6-week measurement period was 13 <span classCombining double low line""inline-formula"">L-1</span>. The [INP] spanned 3 orders of magnitude and showed a general increase from mid-February until early April. No single dominant local or regional sources of INPs in the boreal environment of southern Finland could be identified. Rather, it is hypothesised that the INPs detected at SMEAR II are a result of long-range transport and dilution of INPs sourced far from the measurement site. Despite high variability, the measured [INP] values fall within the range expected for the [INP] measured elsewhere under similar thermodynamic conditions. The [INP] did not correlate with any of the examined parameters during the entire field campaign, indicating that no one single parameter can be used to predict the [INP] at the measurement location during the examined time period. The absence of a correlation across the entire field campaign also suggests that a variety of particles act as INPs at different times, although it was indirectly determined that ambient INPs are most likely within the size range of 0.1-0.5 <span classCombining double low line""inline-formula"">μm</span> in diameter on average. On shorter timescales, several particle species correlated well with the [INP]. Depending on the meteorological conditions, black carbon (BC), supermicron biological particles and sub-0.1 <span classCombining double low line""inline-formula"">μm</span> particles, most likely nanoscale biological fragments such as ice-nucleating macromolecules (INMs), correlated with the INP signal. However, an increase in the concentration of any of these particle species may not necessarily lead to the increase in the [INP]; the reasons for this remain unknown. Limitations of the instrumental set-up and the necessity for future field INP studies are addressed.</p>. © Author(s) 2020."
"57216950962;6701518904;","The vertical structure and spatial variability of lower-tropospheric water vapor and clouds in the trades",2020,"10.5194/acp-20-6129-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085495551&doi=10.5194%2facp-20-6129-2020&partnerID=40&md5=a36e22f740023a2ccf9b2cbff1457a55","Horizontal and vertical variability of water vapor is omnipresent in the tropics, but its interaction with cloudiness poses challenges for weather and climate models. In this study we compare airborne lidar measurements from a summer and a winter field campaign in the tropical Atlantic with high-resolution simulations to analyze the water vapor distributions in the trade wind regime, its covariation with cloudiness, and their representation in simulations. Across model grid spacing from 300m to 2.5km, the simulations show good skill in reproducing the water vapor distribution in the trades as measured by the lidar. An exception to this is a pronounced moist model bias at the top of the shallow cumulus layer in the dry winter season which is accompanied by a humidity gradient that is too weak at the inversion near the cloud top. The model's underestimation of water vapor variability in the cloud and subcloud layer occurs in both seasons but is less pronounced than the moist model bias at the inversion. Despite the model's insensitivity to resolution from hecto- to kilometer scale for the distribution of water vapor, cloud fraction decreases strongly with increasing model resolution and is not converged at hectometer grid spacing. The observed cloud deepening with increasing water vapor path is captured well across model resolution, but the concurrent transition from cloud-free to low cloud fraction is better represented at hectometer resolution. In particular, in the wet summer season the simulations with kilometer-scale resolution overestimate the observed cloud fraction near the inversion but lack condensate near the observed cloud base. This illustrates how a model's ability to properly capture the water vapor distribution does not necessarily translate into an adequate representation of shallow cumulus clouds that live at the tail of the water vapor distribution. © 2020 Copernicus GmbH. All rights reserved."
"56567409000;35509639400;7201504886;","Estimating the Shallow Convective Mass Flux from the Subcloud-Layer Mass Budget",2020,"10.1175/JAS-D-19-0135.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090074290&doi=10.1175%2fJAS-D-19-0135.1&partnerID=40&md5=8ef1c9000a67dda823c2e60331f8f7d1","This paper develops a method to estimate the shallow-convective mass flux M at the top of the subcloud layer as a residual of the subcloud-layer mass budget. The ability of the mass-budget estimate to reproduce the mass flux diagnosed directly from the cloud-core area fraction and vertical velocity is tested using real-case large-eddy simulations over the tropical Atlantic. We find that M reproduces well the magnitude, diurnal cycle, and day-to-day variability of the core-sampled mass flux, with an average root-mean-square error of less than 30% of the mean. The average M across the four winter days analyzed is 12 mm s21, where the entrainment rate E contributes on average 14 mm s21 and the large-scale vertical velocity W contributes 22 mm s21. We find that day-to-day variations in M are mostly explained by variations in W, whereas E is very similar among the different days analyzed. Instead E exhibits a pronounced diurnal cycle, with a minimum of about 10 mm s21 around sunset and a maximum of about 18 mm s21 around sunrise. Application of the method to dropsonde data from an airborne field campaign in August 2016 yields the first measurements of the mass flux derived from the mass budget, and supports the result that the variability in M is mostly due to the variability in W. Our analyses thus suggest a strong coupling between the day-to-day variability in shallow convective mixing (as measured by M) and the large-scale circulation (as measured by W). Application of the method to the EUREC4A field campaign will help evaluate this coupling, and assess its implications for cloud-base cloudiness. Ó 2020 American Meteorological Society."
"55653573700;6701689811;35577097300;7006837187;","Vertical profiles of submicron aerosol single scattering albedo over the Indian region immediately before monsoon onset and during its development: Research from the SWAAMI field campaign",2020,"10.5194/acp-20-4031-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082969524&doi=10.5194%2facp-20-4031-2020&partnerID=40&md5=c52fdfeca2dd67dd84665307fd3bfc60","Vertical structures of aerosol single scattering albedo (SSA), from near the surface through the free troposphere, have been estimated for the first time at distinct geographical locations over the Indian mainland and adjoining oceans, using in situ measurements of aerosol scattering and absorption coefficients aboard the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft during the South West Asian Aerosol Monsoon Interactions (SWAAMI) campaign from June to July 2016. These are used to examine the spatial variation of SSA profiles and also to characterize its transformation from just prior to the onset of Indian Summer Monsoon (June 2016) to its active phase (July 2016). Very strong aerosol absorption, with SSA values as low as 0.7, persisted in the lower altitudes (< 3 km) over the Indo-Gangetic Plains (IGP), prior to the monsoon onset, with a west-to-east gradient; lower values occurred in the north-western arid regions, peaking in the central IGP and somewhat decreasing towards the eastern end. During the active phase of the monsoon, the SSA is found to increase remarkably, indicating far less absorption. Nevertheless, significant aerosol absorption persisted in the lower and middle troposphere over the IGP. Inputting these SSA and extinction profiles into a radiative transfer model, we examined the effects of using height-resolved information in estimating atmospheric heating rates due to aerosols, over similar estimates made using a single columnar value. It was noted that use of a single SSA value leads to an underestimation (overestimation) of the heating rates over regions with low (high) SSA, emphasizing the importance of height-resolved information. Further, the use of realistic profiles showed significant heating of the atmosphere by submicron aerosol absorption at the middle troposphere, which may have strong implications for clouds and climate. © 2020 by ASME."
"7005528388;7404829395;7005729142;7102018821;25227357000;57213925072;","Combining In Situ and Satellite Observations to Understand the Vertical Structure of Tropical Anvil Cloud Microphysical Properties During the TC4 Experiment",2020,"10.1029/2020EA001147","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083680598&doi=10.1029%2f2020EA001147&partnerID=40&md5=84374b4940e0c8ac06f48d73f92be9fa","Tropical anvil clouds have a profound impact on Earth's weather and climate. Their role in Earth's energy balance and hydrologic cycle is heavily modulated by the vertical structure of the microphysical properties for various hydrometeors in these clouds and their dependence on the ambient environmental conditions. Accurate representations of the variability and covariability of such vertical structures are key to both the satellite remote sensing of cloud and precipitation and numerical modeling of weather and climate, which remain a challenge. This study presents a new method to combine vertically resolved observations from CloudSat radar reflectivity and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation cloud masks with probability distributions of cloud microphysical properties and the ambient atmospheric conditions from detailed in situ measurements on tropical anvils sampled during the National Aeronautics and Space Administration TC4 (Tropical Composition, Cloud and Climate Coupling) mission. We focus on the microphysical properties of the vertical distribution of ice water content, particle size distributions, and effective sizes for different hydrometeors, including ice particles and supercooled liquid droplets. Results from this method are compared with those from in situ data alone and various CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation cloud retrievals. The sampling limitation of the field experiment and algorithm limitations in the current retrievals is highlighted, especially for the liquid cloud particles, while a generally good agreement with ice cloud microphysical properties is seen from different methods. While the method presented in this study is applied to tropical anvil clouds observed during TC4, it can be readily employed to study a broad range of ice clouds sampled by various field campaigns. ©2020. The Authors."
"57192700976;57204886915;36868795400;22954298000;36054921000;","Mechanisms of Convective Clustering During a 2-Day Rain Event in AMIE/DYNAMO",2020,"10.1029/2019MS001907","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083278084&doi=10.1029%2f2019MS001907&partnerID=40&md5=ca78971955ee1fd4c5b6121c6a667110","Physical mechanisms that are key to observed convective clustering in 2-day rain events are examined. Previous analysis of the 2-day rain events during the Atmospheric Radiation Measurement Madden-Julian Oscillation Investigation Experiment (AMIE)/Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign data revealed two distinct phases of convective clustering. Using a cloud-system-resolving model, we perform a series of intervention experiments to investigate the underlying mechanisms for convective clustering in each phase. In the developing phase, in addition to previously emphasized processes such as the cold pool-updraft interaction and moisture-convection feedbacks, our results show that the vertical wind shear in the lower free troposphere is a critical factor for convective clustering. Stronger lower free-tropospheric wind shear increases the entrainment of environmental air into updrafts and prevents convective clouds from being omnipresent. This result suggests that stronger vertical wind shear in the lower free troposphere can help spatially organize the convection, even for non–squall-line-type convective systems. In the decaying phase, the cold pool-updraft interaction becomes less effective in aggregating convective clouds because the boundary layer is widely cooled by stratiform precipitation. Instead, the mesoscale downdraft driven by the stratiform precipitation becomes the dominant factor to maintain the relatively aggregated convection. Additionally, removing horizontal variations in radiative heating has no impact on convective clustering on this 2-day time scale, even in the decaying phase when stratiform clouds are widespread. The implication of these results for improving the representation of mesoscale convective organization in convection schemes is discussed. ©2020. The Authors."
"57215418159;56030635600;6602364115;","Configuring les based on dropsonde data in sparsely sampled areas in the subtropical Atlantic",2020,"10.1175/JAMC-D-19-0013.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080895695&doi=10.1175%2fJAMC-D-19-0013.1&partnerID=40&md5=9bb018c13c252639a60752aeef70723a","This study explores the question of how field campaign data, gathered over a large area that is poorly sampled, can be used to make large-eddy simulation (LES) realizations more representative of the local conditions. To this purpose, dropsonde data recorded during the first Next-Generation Aircraft Remote Sensing for Validation Studies (NARVAL)-South campaign, in the marine subtropical North Atlantic, are blended into the forcing data. Control simulations are driven by time-dependent forcings derived from a combination of analyses and short-range weather forecasts, using weak nudging to prevent excessive model drift. A second set of simulations is driven by forcing data with dropsonde profiles included at the time points of their release. Metrics are designed to (i) quantify the impact on the boundary layer vertical profiles as a result of nudging toward the dropsondes and (ii) use a probabilistic method to allow a fair comparison of the inversion strengths in the simulations and observations. The simulations show strong time variation in the cloud-layer depth on relatively short time scales, which is commensurate with recent observational studies in the area. Nudging toward dropsondes improves the representation of the atmospheric profiles throughout the depth of the boundary layer in all simulations. However, the impact on the inversion strength is less pro-nounced. All impacts persist for some time after the dropsonde time point, depending on the intensity of the nudging and the nudging time window. The sensitivity of the results to nudging details and vertical resolution is assessed. © 2020 American Meteorological Society."
"56421910800;6602994648;6603446872;","Analyses of namibian seasonal salt pan crust dynamics and climatic drivers using landsat 8 time-series and ground data",2020,"10.3390/rs12030474","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080870497&doi=10.3390%2frs12030474&partnerID=40&md5=b207a776fe71981bb2bfe4fc826c3284","Salt pans are highly dynamic environments that are difficult to study by in situ methods because of their harsh climatic conditions and large spatial areas. Remote sensing can help to elucidate their environmental dynamics and provide important constraints regarding their sedimentological, mineralogical, and hydrological evolution. This study utilizes spaceborne multitemporal multispectral optical data combined with spectral endmembers to document spatial distribution of surface crust types over time on the Omongwa pan located in the Namibian Kalahari. For this purpose, 49 surface samples were collected for spectral and mineralogical characterization during three field campaigns (2014-2016) reflecting different seasons and surface conditions of the salt pan. An approach was developed to allow the spatiotemporal analysis of the salt pan crust dynamics in a dense time-series consisting of 77 Landsat 8 cloud-free scenes between 2014 and 2017, covering at least three major wet-dry cycles. The established spectral analysis technique Sequential Maximum Angle Convex Cone (SMACC) extraction method was used to derive image endmembers from the Landsat time-series stack. Evaluation of the extracted endmember set revealed that the multispectral data allowed the differentiation of four endmembers associated with mineralogical mixtures of the crust's composition in dry conditions and three endmembers associated with flooded or muddy pan conditions. The dry crust endmember spectra have been identified in relation to visible, near infrared, and short-wave infrared (VNIR-SWIR) spectroscopy and X-ray diffraction (XRD) analyses of the collected surface samples. According these results, the spectral endmembers are interpreted as eorescent halite crust, mixed halite-gypsum crust, mixed calcite quartz sepiolite crust, and gypsum crust. For each Landsat scene the spatial distribution of these crust types was mapped with the Spectral Angle Mapper (SAM) method and significant spatiotemporal dynamics of the major surface crust types were observed. Further, the surface crust dynamics were analyzed in comparison with the pan's moisture regime and other climatic parameters. The results show that the crust dynamics are mainly driven by flooding events in the wet season, but are also influenced by temperature and aeolian activity in the dry season. The approach utilized in this study combines the advantages of multitemporal satellite data for temporal event characterization with advantages from hyperspectral methods for the image and ground data analyses that allow improved mineralogical differentiation and characterization. © 2020 by the authors."
"57218450611;25647939800;9535769800;7401945370;","Impact of latent heat flux modifications on the reproduction of a Madden-Julian oscillation event during the 2015 Pre-YMC campaign using a global cloud-system-resolving model",2020,"10.2151/SOLA.16A-003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089230626&doi=10.2151%2fSOLA.16A-003&partnerID=40&md5=0afe1ede384665af6bf0c377fcff569b","We show that a modification to the latent heat flux (LHF) formulation in Non-hydrostatic Icosahedral Atmospheric Model (NICAM) impacts the representation of a Madden-Julian oscillation (MJO) event during the Pre-Years of the Maritime Continent (Pre-YMC) field campaign in 2015. First, we compare the LHFs computed by the standard NICAM setting with those estimated from the ship observation during Pre-YMC. In this comparison, the NICAM LHF is smaller than observation in the low wind speed region and larger in the high wind speed region. Consequently, the MJO signal weakens when it passes over the Maritime Continent (MC). Next, sensitivity experiments are conducted with a modification to the threshold minimum wind speed in the bulk formula, to enhance the LHFs in the low wind speed region. With this modification, propagation of the MJO is better simulated over the MC, although a bias still remains without corrections in the high wind speed regions. This result indicates that increasing the LHF in the low wind speed region likely contributes to a more effective accumulation of moisture over the eastern MC region and consequently allows the MJO to pass over the MC in the model. © The Author(s) 2020."
"22986726400;6603768446;7005890897;7005729142;6506385754;7102278892;10042394700;56421721900;7005071296;22036874400;57190585769;","Impact of mass–size parameterizations of frozen hydrometeors on microphysical retrievals: Evaluation by matching radar to in situ observations from GCPEX and OLYMPEx",2020,"10.1175/JTECH-D-19-0104.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086306922&doi=10.1175%2fJTECH-D-19-0104.1&partnerID=40&md5=baa6f27c7bb0f361db0f97a38cc77611","This article illustrates how multifrequency radar observations can refine the mass–size parameterization of frozen hydrometeors in scattering models and improve the correlation between the radar observations and in situ measurements of microphysical properties of ice and snow. The data presented in this article were collected during the GPM Cold Season Precipitation Experiment (GCPEx) (2012) and Olympic Mountain Experiment (OLYMPEx) (2015) field campaigns, where the true mass–size relationship was not measured. Starting from size and shape distributions of ice particles measured in situ, scattering models are used to simulate an ensemble of reflectivity factors for various assumed mass–size parameterizations (MSP) of the power-law type. This ensemble is then collocated to airborne and ground-based radar observations, and the MSPs are refined by retaining only those that reproduce the radar observations to a prescribed level of accuracy. A versatile ‘‘retrieval dashboard’’ is built to jointly analyze the optimal MSPs and associated re-trievals. The analysis shows that the optimality of an MSP depends on the physical assumptions made in the scattering simulators. This work confirms also the existence of a relationship between parameters of the optimal MSPs. Through the MSP optimization, the retrievals of ice water content M and mean diameter Dm seem robust to the change in meteorological regime (between GCPEx and OLYMPEx); whereas the retrieval of the diameter spread Sm seems more campaign dependent. © 2020 American Meteorological Society."
"7403577184;14019348000;7201587909;7005461477;7202772927;7401701196;","Polarimetric radar characteristics of simulated and observed intense convective cores for a midlatitude continental and tropical maritime environment",2020,"10.1175/JHM-D-19-0185.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083547877&doi=10.1175%2fJHM-D-19-0185.1&partnerID=40&md5=01f3412ee6b9842ba82bcdc2a472ff40","This study contrasts midlatitude continental and tropical maritime deep convective cores using polarimetric radar observables and retrievals from selected deep convection episodes during the MC3E and TwPICE field campaigns. The continental convective cores produce stronger radar reflectivities throughout the profiles, while maritime convective cores produce more positive differential reflectivity Zdr and larger specific differential phase Kdp above the melting level. Hydrometeor identification retrievals revealed the presence of large fractions of rimed ice particles (snow aggregates) in the continental (maritime) convective cores, consistent with the Zdr and Kdp observations. The regional cloud-resolving model simulations with bulk and size-resolved bin microphysics are conducted for the selected cases, and the simulation outputs are converted into polarimetric radar signals and retrievals identical to the observational composites. Both the bulk and the bin microphysics reproduce realistic land and ocean (L-O) contrasts in reflectivity, polarimetric variables of rain drops, and hydrometeor profiles, but there are still large uncertainties in describing Zdr and Kdp of ice crystals associated with the ice particle shapes/orientation assumptions. Sensitivity experiments are conducted by swapping background aerosols between the continental and maritime environments, revealing that background aerosols play a role in shaping the distinct L-O contrasts in radar reflectivity associated with raindrop sizes, in addition to the dominant role of background thermodynamics. © 2020 American Meteorological Society."
"57195056873;55277641000;57208383202;57208884909;","Assessing the Effects of Microphysical Scheme on Convective and Stratiform Characteristics in a Mei-Yu Rainfall Combining WRF Simulation and Field Campaign Observations",2020,"10.1155/2020/8231320","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082664264&doi=10.1155%2f2020%2f8231320&partnerID=40&md5=5d9d129e1e32c9c00f509c8df9e4e69c","Microphysics parameterization becomes increasingly important as the model grid spacing increases toward convection-resolving scales. Using observations from a field campaign for Mei-Yu rainfall in China, four bulk cloud microphysics schemes in the Weather Research and Forecasting (WRF) model were evaluated with respect to their ability to simulate precipitation, structure, and cloud microphysical properties over convective and stratiform regimes. These are the Thompson (THOM), Morrison graupel/hail (MOR_G/H), Stony Brook University (SBU_YLIN), and WRF double-moment six-class microphysics graupel/hail (WDM6_G/H). All schemes were able to predict the rain band but underestimated the total precipitation by 23%-35%. This is mainly attributed to the underestimation of stratiform precipitation and overestimation of convective rain. For the vertical distribution of radar reflectivity, many problems remain, such as lower reflectivity values aloft in both convective and stratiform regions and higher reflectivity values at middle level. Each bulk scheme has its advantages and shortcomings for different cloud regimes. Overall, the discrepancies between model output and observations mostly exist in the midlevel to upper level, which results from the inability of the model to accurately represent the particle size distribution, ice processes, and storm dynamics. Further observations from major field campaigns and more detailed evaluation are still necessary. © 2020 Lin Liu et al."
"6506674216;56528214600;57188758598;57210885692;23668415500;36458602300;12803904100;15742781500;55788390500;7404955059;","Evaluation of ARM tethered-balloon system instrumentation for supercooled liquid water and distributed temperature sensing in mixed-phase Arctic clouds",2019,"10.5194/amt-12-6845-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077202844&doi=10.5194%2famt-12-6845-2019&partnerID=40&md5=cfb7500596dd2df43af9f1b2d8311d77","<p>A tethered-balloon system (TBS) has been developed and is being operated by Sandia National Laboratories (SNL) on behalf of the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) User Facility in order to collect in situ atmospheric measurements within mixed-phase Arctic clouds. Periodic tethered-balloon flights have been conducted since 2015 within restricted airspace at ARM's Advanced Mobile Facility 3 (AMF3) in Oliktok Point, Alaska, as part of the AALCO (Aerial Assessment of Liquid in Clouds at Oliktok), ERASMUS (Evaluation of Routine Atmospheric Sounding Measurements using Unmanned Systems), and POPEYE (Profiling at Oliktok Point to Enhance YOPP Experiments) field campaigns. The tethered-balloon system uses helium-filled 34&thinsp;m<span classCombining double low line""inline-formula"">3</span> helikites and 79 and 104&thinsp;m<span classCombining double low line""inline-formula"">3</span> aerostats to suspend instrumentation that is used to measure aerosol particle size distributions, temperature, horizontal wind, pressure, relative humidity, turbulence, and cloud particle properties and to calibrate ground-based remote sensing instruments.</p> <p>Supercooled liquid water content (SLWC) sondes using the vibrating-wire principle, developed by Anasphere Inc., were operated at Oliktok Point at multiple altitudes on the TBS within mixed-phase clouds for over 200&thinsp;h. Sonde-collected SLWC data were compared with liquid water content derived from a microwave radiometer, Ka-band ARM zenith radar, and ceilometer at the AMF3, as well as liquid water content derived from AMF3 radiosonde flights. The in situ data collected by the Anasphere sensors were also compared with data collected simultaneously by an alternative SLWC sensor developed at the University of Reading, UK; both vibrating-wire instruments were typically observed to shed their ice quickly upon exiting the cloud or reaching maximum ice loading. Temperature sensing measurements distributed with fiber optic tethered balloons were also compared with AMF3 radiosonde temperature measurements. Combined, the results indicate that TBS-distributed temperature sensing and supercooled liquid water measurements are in reasonably good agreement with remote sensing and radiosonde-based measurements of both properties. From these measurements and sensor evaluations, tethered-balloon flights are shown to offer an effective method of collecting data to inform and constrain numerical models, calibrate and validate remote sensing instruments, and characterize the flight environment of unmanned aircraft, circumventing the difficulties of in-cloud unmanned aircraft flights such as limited flight time and in-flight icing.</p>. © 2019 Copernicus GmbH. All rights reserved."
"57196354642;56646265500;6603231929;36000595000;6602134507;23009343400;6701404949;7004838931;","Wintertime aerosol measurements during the Chilean Coastal Orographic Precipitation Experiment",2019,"10.5194/acp-19-12377-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073474342&doi=10.5194%2facp-19-12377-2019&partnerID=40&md5=60a2a5cb4af3ff6b35a8526aebe42a71","The Chilean Coastal Orographic Precipitation Experiment (CCOPE) was a 3-month field campaign (June, July and August 2015) that investigated wintertime coastal rain events. Reported here are analyses of aerosol measurements made at a coastal site during CCOPE. The aerosol monitoring site was located near Arauco, Chile. Aerosol number concentrations and aerosol size distributions were acquired with a condensation particle counter (CPC) and an ultra high sensitivity aerosol spectrometer (UHSAS). Arauco CPC data were compared to values measured at the NOAA observatory Trinidad Head (THD) on the northern Pacific coast of California. The winter-averaged CPC concentration at Arauco is 2971±1802 cm-3; at THD the average is 1059±855 cm-3. Despite the typically more pristine South Pacific region, the Arauco average is larger than at THD (p &lt; 0:01). Aerosol size distributions acquired during episodes of onshore flow were analyzed with Kohler theory and used to parameterize cloud condensation nuclei activation spectra. In addition, sea salt aerosol (SSA) concentration was parameterized as a function of sea surface wind speed. It is anticipated these parameterizations will be applied in modeling of wintertime Chilean coastal precipitation. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License."
"24472110700;7003875148;","A process-based climatological evaluation of AIRS level 3 tropospheric thermodynamics over the high-latitude arctic",2019,"10.1175/JAMC-D-18-0306.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073327032&doi=10.1175%2fJAMC-D-18-0306.1&partnerID=40&md5=893a9691f7119582b990fb16f45fede6","Measurements from spaceborne sensors have the unique capacity to fill spatial and temporal gaps in ground-based atmospheric observing systems, especially over the Arctic, where long-term observing stations are limited to pan-Arctic landmasses and infrequent field campaigns. The AIRS level 3 (L3) daily averaged thermodynamic profile product is widely used for process understanding across the sparsely observed Arctic atmosphere. However, detailed investigations into the accuracy of the AIRS L3 thermodynamic profiles product using in situ observations over the high-latitude Arctic are lacking. To address this void, we compiled a wealth of radiosounding profiles from long-term Arctic land stations and included soundings from intensive icebreaker-based field campaigns. These are used to evaluate daily mean thermodynamic profiles from the AIRS L3 product so that the community can understand to what extent such data records can be applied in scientific studies. Results indicate that, while the mid-to upper-troposphere temperature and specific humidity are captured relatively well by AIRS, the lower troposphere is susceptible to specific seasonal, and even monthly, biases. These differences have a critical influence on the lower-tropospheric stability structure. The relatively coarse vertical resolution of the AIRS L3 product, together with infrared radiation through persistent low Arctic cloud layers, leads to artificial thermodynamic structures that fail to accurately represent the lower Arctic atmosphere. These thermodynamic errors are likely to introduce artificial errors in the boundary layer structure and analysis of associated physical processes. © 2019 American Meteorological Society."
"7004323635;56938999600;7102278892;57213199066;6603552777;34882043200;23012437100;57213197858;","Active and Passive Radiative Transfer Simulations for GPM-Related Field Campaigns",2019,"10.1109/IGARSS.2019.8898923","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077721085&doi=10.1109%2fIGARSS.2019.8898923&partnerID=40&md5=fe01a11de8c6a40d220f43b1a7127591","Using a three-dimensional radiative transfer model combined with cloud-resolving model output, we simulate active and passive sensor observations of clouds and precipitaiton. This combination of tools allows us to diagnose the contributions of various hydrometeor types. Radar multiple scattering is most closely associated with the presence of graupel. At W-band, massive amounts multiple scattering in deep convection can decorrelate the reflectivity profile from the vertical structure, but for less intense events, multiple scattering could be a useful indicator of riming. For passive sensors, polarization differences at 166 GHz indicate the presence of horizontally-aligned frozen particles with pronounced aspect ratios, while high concentrations of more isotropic aggregates and graupel dampen the polarization difference while also contributing to the lowest brightness temperature depressions. The insights into remote sensing measurements will facilitate the development of improved algorithms and advanced sensors. © 2019 IEEE."
"6602574676;36098286300;","A Unique Airborne Multi-Angular Data Set for Different Applications in Remote Sensing",2019,"10.1109/IGARSS.2019.8899818","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077684393&doi=10.1109%2fIGARSS.2019.8899818&partnerID=40&md5=9d502c0518073cc2f54fe0c4f775c530","The Cloud Absorption Radiometer (CAR) Science Team, and the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) recently announced the release of CAR data for multiple scientific missions. These data sets consist of measurements of spectral radiance acquired by the CAR instrument. The CAR has been deployed on research aircrafts during numerous field campaigns around the world, with measurements spanning from years 1991 to 2017. These data may be used to evaluate the ability of analytical models to reproduce observed directional signatures and to develop bidirectional reflectance-distribution function (BRDF) models that are suitable for sub-kilometer- scale satellite observations over both homogeneous and heterogeneous landscape types around the world. All of the data are now public and accessible in netCDF-4 format. The full suite of CAR data products are available at the GES DISC. (https://disc.gsfc.nasa.gov/datasets?keywords=CAR). © 2019 IEEE."
"7003414581;57196028344;55444637900;22954523900;8927405700;36651412700;57202475063;24366038500;","Lidar/radar approach to quantify the dust impact on ice nucleation in mid and high level clouds",2019,"10.1051/e3sconf/20199904003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067815940&doi=10.1051%2fe3sconf%2f20199904003&partnerID=40&md5=e9a184cfff565ea2c55f8e2baa4b1186","We present the first attempt of a closure experiment regarding the relationship between ice nucleating particle concentration (INPC) and ice crystal number concentration (ICNC), solely based on active remote sensing. The approach combines aerosol and cloud observations with polarization lidar, Doppler lidar, and cloud radar. Several field campaigns were conducted on the island of Cyprus in the Eastern Mediterranean from 2015-2018 to study heterogeneous ice formation in altocumulus and cirrus layers embedded in Saharan dust. A case study observed on 10 April 2017 is discussed in this contribution. © 2019 The Authors, published by EDP Sciences."
"57190422776;8657166100;12800966700;56358933300;36573180000;7003535385;","Uncertainty of the Ice Particles Median Mass Diameters Retrieved from the HAIC-HIWC Dataset: A Study of the Influence of the Mass Retrieval Method",2019,"10.4271/2019-01-1983","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067981065&doi=10.4271%2f2019-01-1983&partnerID=40&md5=62c0eb975f521e3b47a6894b7eb453ba","In response to the ice crystal icing hazard identified twenty years ago, aviation industry, regulation authorities, and research centers joined forces into the HAIC-HIWC international collaboration launched in 2012. Two flight campaigns were conducted in the high ice water content areas of tropical mesoscale convective systems in order to characterize this environment conducive to ice crystal icing. Statistics on cloud microphysical properties, such as Ice Water Content (IWC) or Mass Median Diameter (MMD), derived from the dataset of in situ measurements are now being used to support icing certification rulemaking and anti-icing systems design (engine and air data probe) activities. This technical paper focuses on methodological aspects of the derivation of MMD. MMD are estimated from PSD and IWC using a multistep process in which the mass retrieval method is a critical step. Complementary to previous studies reporting on MMD values calculated from the HAIC-HIWC dataset, this paper deals with the uncertainty in MMD by comparing two different approaches for the retrieval of the mass-size (m-D) relationship. The analysis encompasses the data collected in the high IWC areas (IWC &gt; 1g.m-3) sampled during the two HAIC-HIWC field campaigns. MMD series are computed using three different mass-size relationships and statistical values are compared. Overall, MMD values are in good agreement, at least for two methods although they imply quite different assumptions. On the variability in MMD values at a given temperature level, results show that MMD may vary significantly from one flight to the other, even though MMD series produced with the different mass retrieval methods follow a similar pattern. A strong temperature dependence is observed regardless the assumption on the m-D relationship, making MMD to increase by more than a factor of 2 as temperature increases from -50°C to -10°C. Finally, the influence on calculated MMD of two different definitions for particle size (Deq and Dmax) is demonstrated. Generally, MMD computed with Dmax are a few percent larger as compared to MMD calculated from Deq definition, supporting the conclusions from previous studies. © 2019 SAE International. All Rights Reserved."
"55241984000;7005968859;7004715270;8586682800;56789763900;55968364300;57149740600;","Classification of aerosol population type and cloud condensation nuclei properties in a coastal California littoral environment using an unsupervised cluster model",2019,"10.5194/acp-19-6931-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066072736&doi=10.5194%2facp-19-6931-2019&partnerID=40&md5=d06f0f4849ba5199b21096169ab4dd01","Aerosol particle and cloud condensation nuclei (CCN) measurements from a littoral location on the northern coast of California at Bodega Bay Marine Laboratory (BML) are presented for approximately six weeks of observations during the boreal winter-spring as part of the CalWater-2015 field campaign. The nature and variability of surface (marine boundary layer, MBL) aerosol populations were evaluated by classifying observations into periods of similar aerosol and meteorological characteristics using an unsupervised cluster model to derive distinct littoral aerosol population types and link them to source regions. Such classifications support efforts to understand the impact of changing aerosol properties on precipitation and cloud development in the region, including during important atmospheric river (AR) tropical moisture advection events. Eight aerosol population types were identified that were associated with a range of impacts from both marine and terrestrial sources. Average measured total particle number concentrations, size distributions, hygroscopicities, and activated fraction spectra between 0.08&thinsp;% and 1.1&thinsp;% supersaturation are given for each of the identified aerosol population types, along with meteorological observations and transport pathways during time periods associated with each type. Five terrestrially influenced aerosol population types represented different degrees of aging of the continental outflow from the coast and interior of California, and their appearance at the BML site was often linked to changes in wind direction and transport pathways. In particular, distinct aerosol populations, associated with diurnal variations in source regions induced by land-and sea-breeze shifts, were classified by the clustering technique. A terrestrial type representing fresh emissions, and/or a recent new particle formation event, occurred in approximately 10% of the observations. Over the entire study period, three marine-influenced population types were identified that typically occurred when the regular diurnal land and sea-breeze cycle collapsed and BML was continuously ventilated by air masses from marine regions for multiple days. These marine types differed from each other primarily in the degree of cloud processing evident in the size distributions, and in the presence of an additional large-particle mode for the type associated with the highest wind speeds. One of the marine types was associated with a multi-day period during which an atmospheric river made landfall at BML. Differences between many of the terrestrial and marine population types in total CCN number concentrations active at a specific supersaturation were often not as pronounced as the associated differences in the corresponding activated fraction spectra, particularly for supersaturations below about 0.4%. This finding was due to the generally higher number concentrations in terrestrial air masses offsetting the lower fraction of particles activating at low supersaturations. At higher supersaturations, CCN concentrations for aged terrestrial types were typically above those of the marine types due to their higher number concentrations. © 2019 Author(s)."
"7102913661;7005461477;7006372688;7005902263;","Introduction to the Deep Convective Clouds and Chemistry (DC3) 2012 Studies",2019,"10.1029/2019JD030944","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070317795&doi=10.1029%2f2019JD030944&partnerID=40&md5=210f329aa0c60df9e804ef2d214129f5","The Deep Convective Clouds and Chemistry (DC3) project aimed to determine the impact of deep, midlatitude continental convective clouds on tropospheric composition and chemistry. The DC3 field campaign was conducted over a broad area of the central United States during May–June 2012. Data collected by DC3 have been extensively analyzed, with many results published in Deep Convective Clouds and Chemistry 2012 Studies (DC3), a joint special section of JGR Atmospheres and Geophysical Research Letters. This paper highlights key results from the DC3 project as an introduction to the special issue. ©2019. American Geophysical Union. All Rights Reserved."
"26533129200;14044750400;7006728825;57201806565;56888739700;55233414500;55384058900;24391639000;57212805825;7201572145;57204951643;7004860305;57203668119;","The NCAS mobile dual-polarisation Doppler X-band weather radar (NXPol)",2018,"10.5194/amt-11-6481-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058067050&doi=10.5194%2famt-11-6481-2018&partnerID=40&md5=0c800a01c45daed351cefb4ac78bdf23","In recent years, dual-polarisation Doppler X-band radars have become a widely used part of the atmospheric scientist's toolkit for examining cloud dynamics and microphysics and making quantitative precipitation estimates. This is especially true for research questions that require mobile radars. Here we describe the National Centre for Atmospheric Science (NCAS) mobile X-band dual-polarisation Doppler weather radar (NXPol) and the infrastructure used to deploy the radar and provide an overview of the technical specifications. It is the first radar of its kind in the UK. The NXPol is a Meteor 50DX manufactured by Selex- Gematronik (Selex ES GmbH), modified to operate with a larger 2.4m diameter antenna that produces a 0.98 halfpower beam width and without a radome. We provide an overview of the technical specifications of the NXPol with emphasis given to the description of the aspects of the infrastructure developed to deploy the radar as an autonomous observing facility in remote locations. To demonstrate the radar's capabilities, we also present examples of its use in three recent field campaigns and its ongoing observations at the NERC Facility for Atmospheric Radio Research (NFARR). © Author(s) 2018."
"57209614011;6701316969;8974584100;56528895600;56912358400;","Combination of optical and SAR sensors for monitoring biomass over corn fields",2018,"10.1109/IGARSS.2018.8518998","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064174386&doi=10.1109%2fIGARSS.2018.8518998&partnerID=40&md5=a0bf92c5770e5cb1e15c3bd7f819c8dc","In this study, a cross-calibration approach was applied to combine RADARSAT-2 and RapidEye sensors for biomass monitoring over corn fields. First, RapidEye and RADARSAT-2 sensors were compared in terms of biomass estimation. Then the estimated biomass from RADARSAT-2 was cross-calibrated with respect to the biomass estimated from RapidEye. Combination of the optical and cross-calibrated Synthetic Aperture Radar (SAR) derived biomass was proposed to have higher temporal resolution biomass maps. Vegetation indices including normalized difference vegetation index (NDVI), red-edge triangular vegetation index (RTVI), simple ratio (SR) and red-edge simple ratio (SRre) were used for modeling of biomass estimation from RapidEye. Water Cloud Model (WCM) was also used for biomass estimation from RADARSAT-2. Data collected during SMAP Validation Experiment 2012 (SMAPVEX12) field campaign was used for validation. The results demonstrate that the accuracies of biomass estimations from RapidEye and RADARSAT-2 are close. For RapidEye, the highest accuracies derived from RTVI index with correlation coefficient (R) of 0.92 and Root Mean Square of (RMSE) of 118.18 gr/m2. The R values derived from RADARSAT-2 is 0.83 and its RMSE is 171.93 gr/m2. After cross-calibration of the biomass derived from RADARSAT-2 versus those derived from RapidEye, the RMSE of estimates dropped by 18.86 gr/m2. © 2018 IEEE."
"6603093035;57194765326;56884168600;6603409281;","Influence of supersaturation on the concentration of ice nucleating particles",2018,"10.1080/16000889.2018.1454809","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045308311&doi=10.1080%2f16000889.2018.1454809&partnerID=40&md5=ab6ea5a10840310588d9bb926633e795","There is a consensus on the increase in ice nucleating particles (INP) concentration from subsaturated to supersaturated water conditions typically associated with clouds (1 ÷ 2%). However, it is important to evaluate the INP concentration trend when water supersaturation further increases, as supercooled clouds contain pockets of high water vapor supersaturation. Three laboratory dry-generated aerosols, two biological (microcrystalline and fibrous cellulose) and one mineral (Arizona test dust), and a field aerosol, sampled on filters, were investigated. Atmospheric aerosol (PM1 and PM10 fractions) was sampled at Capo Granitola (CG, coastal site in Sicily) and the National Research Council (CNR) research area in Bologna (urban background site). The dynamic filter processing chamber (DFPC) was used to explore the ice nucleation of the sampled aerosol in the deposition and condensation freezing modes. Experiments were performed from water subsaturated conditions (water saturation ratio Sw = 0.94) to Sw = 1.1, at T = −22 °C. At CG we considered separately events with a prevalent contribution of marine aerosol, and those showing a contribution of both marine and continental aerosols. An increase in INP concentration, the aerosol activated fraction (AF) and ice nucleation active surface site density (ns) from water subsaturated conditions to Sw = 1.02 was measured in both laboratory and field campaigns. This increase is due to the transition from deposition nucleation to condensation freezing. The highest increases in AF and ns from Sw = 1.02 to Sw = 1.1 were obtained for urban and mixed aerosol and the lowest for marine aerosol. Samplings performed in Bologna showed a high increase in the average INP concentration from PM1 to PM10. Our results show the importance of performing measurements of ice nucleation efficiency for continental aerosol even at supersaturation values higher than those typically associated with clouds, and also considering the contribution of coarse aerosol particles. © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"6602574676;36098286300;","Impact of forests on snow albedo: Lessons from the SnowEx campaign",2017,"10.1109/IGARSS.2017.8127225","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041856250&doi=10.1109%2fIGARSS.2017.8127225&partnerID=40&md5=0dfd4a5b0c5c6d3be230f134f1fdaae0","There is a clear and urgent need to quantify seasonally varying snow water equivalent and albedo. In this study, the snow bidirectional distribution function (BRDF) from NASA Cloud Absorption Radiometer (CAR) will be used to analyze the impact of forests on snow albedo based on measurements from SnowEx field campaign in western Colorado over Grand Mesa and Senator Beck. Seasonal snow cover is the largest single component of the cryosphere in areal extent (covering an average of 46M km2 of Earth's surface (31 % of land areas) each year. Current space-based techniques underestimate storage of snow water equivalent (SWE) by as much as 50% [1, 2]. That number is likely to be greater in the boreal forest and other densely-forested areas around the globe, with the boreal forest being the largest biome on Earth (20M km2). © 2017 IEEE."
"6603063133;55880185200;11739599800;56269722300;22635720500;6505805689;36729497200;23027982900;36173205500;15127610600;11839521200;7006387246;6506936772;7006005916;37116464700;55195577800;7006131104;7003442486;23018110700;56398509100;8697462600;36459607700;57188923522;12645700600;8546395600;6603201426;16031086600;55428286800;22980987200;55879760100;55017283500;8944519400;22136612400;7007083667;55894188500;35222441400;15129229400;","Evaluation of seven chemistry transport models in the framework of eurodelta III intercomparison exercise",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047221356&partnerID=40&md5=9a070e0f78c0c61930ccf641cbb2de38","The EURODELTA III (ED-III) exercise aimed to perform a comprehensive chemistry transport model inter-comparison study exploiting the data from four intensive measurement campaigns carried out by EMEP. The campaigns were held in different seasons (1–30 June 2006; 8 January–4 February 2007; 17 September–15 October 2008; 25 February–26 March 2009) thus allowing to test the influence of different meteorological conditions on models’ results. Seven models simulated the air quality over the whole Europe: CHIM (CHIMERE; version chim2013), EMEP (rv 4.1.3), LOTO (LOTOSEUROS, V1.8), CAMX (CAMx, v5.41 VBS), MINNI (version 4.7), CMAQ (V5.0.1) and RCG (v.2.1). Except CMAQ, all the models performed simulations over the same domain with the same horizontal spatial resolution. They also used the same input data (emissions, meteorology and boundary conditions) as much as possible. This work presents and discusses the behaviour of the models with regard to the criteria defined in the EU Directive on Air Quality 2008/50/EC for the air concentrations of PM10, PM2.5, O3, NO2 and SO2 and to the meteorological conditions. The wet deposition of sulphate (S) (WSOx), of oxidized and reduced nitrogen (N) (WNOx and WNHx, respectively) and the air concentrations of the deposited species were also investigated. Furthermore, a comparison of the capacities of air quality models to simulate carbonaceous aerosols (elemental (EC) and organic carbon (OC)) in Europe was conducted, given the diversity in modelling natural precursor emissions and formation and evolution of organic species, both natural and anthropogenic. In addition to EMEP data, the evaluation of models’ output included AirBase data and meteorological data from more than 2000 synoptic stations. The simulated concentrations of organic aerosol (OA) were compared to measurements available from two intensive measurement field campaigns carried out in a joint framework of EMEP and EUCAARI (the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions) project in 2008 and 2009. © 2018 Hungarian Meteorological Service. All Rights Reserved."
"57189714186;6506537159;7102743829;","Evaluation of warm-rain microphysical parameterizations in mesoscale simulations of the cloudy marine boundary layer",2016,"10.1175/MWR-D-15-0266.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974814380&doi=10.1175%2fMWR-D-15-0266.1&partnerID=40&md5=93ecd53bd562d2ef649fead96b17c9f7","Several warm-rain microphysical parameterizations are evaluated in a regional forecast model setting (using the Naval Research Laboratory's Coupled Ocean-Atmosphere Mesoscale Prediction System) by evaluating how accurately the model is able to represent the marine boundary layer (MBL). Cloud properties from a large suite of simulations using different parameterizations and concentrations of cloud condensation nuclei (CCN) are compared to ship-based observations from the Variability of theAmericanMonsoon Systems (VAMOS) Ocean-Cloud-Atmosphere-Land Study-Regional Experiment (VOCALS-REx) field campaign conducted over the southeastern Pacific (SEP). As in previous studies, the simulations systematically underestimate liquid water path and MBL cloud depth. On the other hand, the simulations overestimate precipitation rates relative to those derived fromthe scanningC-band radar on board the ship.Most of the simulations exhibit a diurnal cycle, although details differ somewhat from a recent observational study. In addition to direct comparisons with the observations, the internal microphysical consistency of simulated MBL cloud properties is assessed by comparing simulation output to a number of observationally and theoretically derived scalings for precipitation and coalescence scavenging. Simulation results are broadly consistent with these scalings, suggesting COAMPS is behaving in a microphysically consistent fashion. However, microphysical consistency as defined in the analysis is highly dependent upon the horizontal resolution of themodel. Excessive depletion of CCN from large coalescence processing rates suggests the importance of parameterizing a source term for CCN or imposing some form of fixed, climatological background CCN concentration. © 2016 American Meteorological Society."
"56591838400;7005054220;7102913661;55314628400;57188971800;7404327420;8916335600;6701640417;7005461477;56045802300;7003479494;36616603800;7004643405;6602743250;","A WRF-Chem flash rate parameterization scheme and LNOx analysis of the 29-30 May 2012 convective event in Oklahoma during DC3",2014,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086813918&partnerID=40&md5=86e2454159576facae81cb40fb08519e","The Deep Convective Clouds and Chemistry (DC3) field campaign in 2012 provided a plethora of aircraft and ground-based observations (e.g., trace gases, lightning and radar) to study deep convective storms, their convective transport of trace gases, and associated lightning occurrence and production of nitrogen oxides (NOx). Based on the measurements taken of the 29-30 May 2012 Oklahoma thunderstorm, an analysis against a Weather Research and Forecasting Chemistry (WRF-Chem) model simulation of the same event at 3-km horizontal resolution was performed. One of the main objectives was to include various flash rate parameterization schemes (FRPSs) in the model and identify which scheme(s) best captured the flash rates observed by the National Lightning Detection Network (NLDN) and Oklahoma Lightning Mapping Array (LMA). The comparison indicates how well the schemes predicted the timing, location, and number of lightning flashes. The FRPSs implemented in the model were based on the simulated thunderstorm's physical features, such as maximum vertical velocity, cloud top height, and updraft volume. Adjustment factors were applied to each FRPS to best capture the observed flash trend and a sensitivity study was performed to compare the range in model-simulated lightning-generated nitrogen oxides (LNOx) generated by each FRPS over the storm's lifetime. Based on the best FRPS, model-simulated LNOx was compared against aircraft measured NOx. The trace gas analysis, along with the increased detail in the model specification of the vertical distribution of lightning flashes as suggested by the LMA data, provide guidance in determining the scenario of NO production per intracloud and cloud-to-ground flash that best matches the NOx mixing ratios observed by the aircraft. © International Conference on Atmospheric Electricity, ICAE 2014"
"7102913661;55502736300;55314628400;7005054220;57188971800;56591838400;","Simulations of lightning-generated NOx for parameterized convection in the WRF-Chem model",2014,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086812671&partnerID=40&md5=75f787357c399801837d29ef383a1bd4","Production of nitrogen oxides (NOx) by lightning is an important precursor for ozone in the upper troposphere. In this study, the prediction of lightning flash rates and lightning-generated NOx in the Weather and Research Forecasting model coupled with Chemistry (WRF-Chem) is evaluated using data from the Deep Convective Clouds and Chemistry (DC3) field campaign. The WRF-Chem simulations are performed at grid spacings of 15 km where convection is parameterized. Thus, lightning flash rate is predicted using the Price and Rind (1992) parameterization, which is based on cloud-top height and is predicted by the level of neutral buoyancy determined in the convective parameterization. By comparing the predicted flash rate to the Oklahoma Lightning Mapping Array data for specific DC3 case studies, we found for the May 29, 2012 severe storm in northern Oklahoma that the lightning parameterization needed to be adjusted by limiting the flash rate location to regions with high cloud condensate content, in order to better match the horizontal spatial distribution and magnitude of observed flash rates. Comparison of predicted NOx mixing ratios in the anvil region of the storm showed that the predicted NOx is 1 to 1.5 times greater than aircraft observations. However, comparison of predicted concentrations to aircraft data collected in the convective outflow (over western North Carolina) 20-22 hours after active convection showed that modeled NOx had similar values to observations. © International Conference on Atmospheric Electricity, ICAE 2014"
"55574733500;15836145000;","Aerosol distictions over Jalisco using satellite information and global model (GOCART): Prospective study",2014,"10.1109/IGARSS.2014.6946376","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84911409365&doi=10.1109%2fIGARSS.2014.6946376&partnerID=40&md5=4b36c83ffcfb5e99413d929485cb03e9","Aerosols play an important role in global climate change. [Reference new IPCC report]. These particles directly affect the radiative budget due to absorption and scattering of radiation. Additionally, aerosols are known to alter various ecosystems, cloud formation and properties, precipitation, air quality and visibility. They also have well-documented impacts on human health. In the last 30 years, progress has been made in remote sensing retrievals of aerosol distribution and properties, using different satellite sensors as well as ground-based sun photometer instruments, monitoring programs, and intensive field campaigns around the world. This paper describes how the study and analysis of satellite-based (CALIPSO) measurements and the Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model make it possible to identify some of the predominant tropospheric aerosols, black carbon and organic carbon. We present the black carbon and organic carbon aerosols and their optical properties by season, within the region of Jalisco México. © 2014 IEEE."
"56097263900;8268569900;7004001508;24451174800;6701549442;","Investigation of landslide kinematics derived from UAV- and ground-based imagery - Precision analysis of 3D point clouds",2013,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897541270&partnerID=40&md5=c2584b1f5678371035654ce0b57b3116","During an eight week field campaign at the Super-Sauze landslide (South French Alps), several UAV- and ground-based photographs have been acquired. Additionally, high-resolution terrestrial laser scanning (TLS) has been performed in order to capture a precise reference data set. The High-resolution and multitemporal, but also disordered and oblique images were used to generate 3D point clouds from Structurefrom- Motion and Multi-View Stereo (SfM-MVS) algorithms. These multi-temporal digital surface models (DSMs) were required for a precise ortho-rectification, as well as for morphometric and kinematic investigations. In order to determine the quality of the point clouds, all photogrammetric data were compared to the time corresponding TLS-based DSMs. The analysis of DSMs and orthophotos is one part of a field experiment that has the objective to characterize the relationship between fracture processes (slidequakes and local tremor events), slope movements, fissure developments and pore water pressure build-up. The main focus of this contribution is a comprehensive evaluation of the SfM-MVS-based point clouds in order to demonstrate the potential but also the limits of such approach."
"7005706662;","Physical connections between atmospheric visibility and regional climate change",2012,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879777844&partnerID=40&md5=35cfebdf25e7183fe0dcd84df0fb3472","Soot, smoke, and dust aerosols are absorbing, leading to significant positive radiative forcing in the atmosphere and negative forcing at the surface. Trends in atmosphere and surface forcing may have implications for trends in the water cycle, irrespective of the global warming signal. Locally, the effects of aerosol absorption may be significant but depend on the local dynamics of clouds and rainfall. Dust outbreaks over the tropical Atlantic Ocean coincide with a northward shift of ITCZ precipitation. This response is a associated with an acceleration on the northern part of the African Easterly Jet driven by the tropospheric temperature perturbation that accompanies the dust outbreaks. These results arise from empirical studies of satellite data specifically designed to confirm controlled experiments performed with models. Aerosols also modify low clouds. For absorbing aerosols there appears to be a competition between greater cloud drop nucleation and cloud ""burn off"". A new field campaign, CARDEX, seeks to quantify the moisture dynamics in the highly polluted marine boundary layer and understand the nature of this competition."
"53879334000;","Geophysical information for teachers: Wave tanks, homemade clouds, glacial goo, and more!",2012,"10.1029/2012EO090020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858060472&doi=10.1029%2f2012EO090020&partnerID=40&md5=d2a43fc384ffcf233f49479d64bbb990","AGU is deeply committed to fostering the next generation of Earth and space scientists. Union activities contribute to this effort in many ways, one of which is partnering with the National Earth Science Teacher's Association (NESTA) to hold the Annual Geophysical Information for Teachers (GIFT) workshop at AGU's annual Fall Meeting. GIFT allows K-12 science teachers to hear about the latest geoscience research from the scientists making the discoveries, explore new classroom resources for their students, and visit exhibits and technical sessions of the AGU meeting for free. In 2011 AGU worked with NESTA to develop an improved rigorous and open application process for scientists and education professionals who wished to work as a team and present their Earth and space science work to teachers, as well as lead the educators in a hands-on, classroom- ready activity. Twenty-four applications were received for five slots, so the selected presentations (on tsunamis, clouds, field campaigns, glaciers, and volcanoes), chosen through a peer- review process, truly represented the best ways of getting cutting-edge science into the classroom."
"36916954400;","Estimation of charge distributions related with individual lightning discharges",2011,"10.1109/APL.2011.6110246","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856109337&doi=10.1109%2fAPL.2011.6110246&partnerID=40&md5=2e8811d25285f01c633f2c933fdf610e","To investigate electric charge distributions in thunderclouds with high time resolution and for individual lighting flashes, VHF Broadband Digital Interferometers (VHF BDITF) and slow antennas are deployed during a field campaign in Darwin, Australia. VHF BDITFs enable us the estimation of locations of negative breakdown, and the lightning channels images inside and outside of thunderclouds. The source locations inside the cloud are equivalent to the positions of positive charges. Electric field changes captured by slow antennas may present the charge amounts, which cause lightning flashes. The combination of above two observations may give us the clear idea of charge distributions, which contribute individual lightning flashes. Both cloud and ground discharges in terms of charge distributions will be discusses in detail. © 2011 IEEE."
"8349977500;7403253796;7005882490;14622650300;7005254328;7101846027;6603684590;","Estimates of aqueous-phase sulfate production from tandem differential mobility analysis",2011,"10.1016/j.atmosenv.2011.06.057","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80051471602&doi=10.1016%2fj.atmosenv.2011.06.057&partnerID=40&md5=1f2a42f61317591ee25cec1f74cdfce6","During June and July of 2004, airborne measurements of size-resolved aerosol properties were made over the coastal Pacific near Marina, California. Tandem differential mobility analysis was used to determine the hygroscopic properties of these aerosols and, subsequently, to examine the change in soluble mass after the aerosol had been cloud-processed. Three of the eight cases analyzed during the field campaign exhibited increased soluble mass attributable to cloud-processing. The calculated change in soluble mass after cloud-processing, derived from measurements made below and above cloud, ranged from 1.08 Υ{hooked} g m-3 to 1.40 Υ{hooked} g m-3. These values are in agreement with those determined using data collected during previous field studies in the same region. Aerosol size distributions measured throughout the study with a Passive Cavity Aerosol Spectrometer Probe were averaged to create a single representative distribution, which was used to examine the impact of the addition of sulfate to a typical aerosol measured during this project. Mass light-scattering efficiencies were calculated for both the initial and cloud-processed size distributions using Mie-Lorenz theory. These calculations show that the increase in mass light-scattering efficiency following passage through a single non-precipitating cloud to be 14%, which is in agreement with findings of previous studies in the same region. This new technique produces results that are consistent with existing methods for measuring in-cloud sulfate production and has the advantage of intrinsic consistency with the hygroscopicity and CCN activity of the aerosol. © 2011 Elsevier Ltd."
"6505932008;6508109309;25953950400;","Experience in applying the Alpert-Stein factor separation methodology to assessing urban land-use and aerosol impacts on precipitation",2011,"10.101x7/CBO9780521191739.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928771450&doi=10.101x7%2fCBO9780521191739.010&partnerID=40&md5=26fe8cf0386de09a3f17d52616bf9a7c","In this chapter, Alpert–Stein Factor Separation (FS) Methodology is used to assess the significance of various land surface characteristics on the development and precipitation characteristics of convective storms occurring downwind of an urban region. In particular, the roles of topography, momentum fluxes, radiative heat fluxes, and latent and sensible heat fluxes are evaluated. The use of this technique in investigating the relative and interactive roles of different nucleating aerosols, including cloud condensation nuclei, giant cloud condensation nuclei, and ice nuclei, on the development, structure, and precipitation processes of tropical convection is also then described. Numerical mesoscale simulations of urban enhanced convection Introduction We briefly review the application of a three-dimensional, cloud-resolving, mesoscale model case study described in Rozoff et al. (2003) to the examination of the impacts of St. Louis, MO, USA, land use and topography on local convective storms. Located within a relatively moist and temperate climate, St. Louis is an ideal city for experimental study since it is relatively isolated from other substantial urban areas and its local geography is devoid of major topography and large bodies of water. Furthermore, St. Louis was the site for a large field campaign in 1971–5, called Project METROMEX (Changnon et al., 1981). That study was dedicated to questions regarding the role of urban areas on weather modification. It is believed the findings for St. Louis are widely applicable to other cities containing similar background conditions. © Cambridge University Press, 2011."
"6603550074;25947956100;55717441600;55262499900;","Select methodology for validating advanced satellite measurement systems",2009,"10.1063/1.3116968","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65649146437&doi=10.1063%2f1.3116968&partnerID=40&md5=327147dc97c280500893408b67c2ad92","Advanced satellite sensors are tasked with improving global measurements of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Measurement system validation is crucial to achieving this goal and maximizing research and operational utility of resultant data. Field campaigns including satellite under-flights with well-calibrated FTS sensors aboard high- altitude aircraft are an essential part of the validation task. This manuscript focuses on an overview of validation methodology developed for assessment of high spectral resolution infrared systems, and includes results of preliminary studies performed to investigate the performance of the Infrared Atmospheric Sounding Interferometer (IASI) instrument aboard the MetOp-A satellite. © 2009 American Institute of Physics."
"36712012600;6701873414;36711275100;57189613211;","The U.S. department of energy's atmospheric radiation measurement climate research facilities on the north slope of alaska",2008,"10.1109/IGARSS.2008.4779350","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649760577&doi=10.1109%2fIGARSS.2008.4779350&partnerID=40&md5=3f148b9858746b165c95f086e9d64ed9","The U.S. Department of Energy (DOE) provides scientific infrastructure and data archives to the international Arctic research community through a national user facility, the ARM Climate Research Facilities (ACRF), located on the North Slope of Alaska. ACRF's role is to provide infrastructure support for climate research, including Arctic research, to the global scientific community. DOE's climate research programs, with a focus on clouds and aerosols and their impact on the radiative budget, define the research scope supported by the Facility. This paper discusses the scientific infrastructure, data streams and archives, planned field campaigns, and opportunities for future collaborative research on the North Slope of Alaska. © 2008 IEEE."
"7202258620;55720332500;7403143315;6701463335;7203001286;7005361537;6603392379;24337589800;14719634400;24339477000;24339251400;14719880500;7801611677;35556482500;57208539111;7003298573;6602504147;6506588028;7003535385;","Modelling regional aerosols: Impact of cloud processing on gases and particles over eastern North America and in its outflow during ICARTT 2004",2008,"10.1007/978-1-4020-8453-9_59","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051705625&doi=10.1007%2f978-1-4020-8453-9_59&partnerID=40&md5=6aeae8551c231d82e53eb1855ed272d1","A regional aerosol model, AURAMS (A Unified Regional Air-quality Modelling System), is used to simulate gases and aerosols over eastern North America for the ICARTT field campaign period during summer 2004. The model performance is evaluated against both ground-based and airborne observations during the field campaign. A model sensitivity study is used to assess the impact of cloud processing on the aerosol characteristics in the air masses over eastern North America and its outflow to the North Atlantic during the study period. © Springer Science + Business Media B.V. 2008."
"6507981312;7006537399;56212055700;36060259300;7006026608;24777124100;","Automated compact EZ LIDARS for aerosol and cloud tracking and wind profiling",2007,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949290662&partnerID=40&md5=13d50f644fa5217190aef11122cd4d30","The EZ Aerosol and Wind LIDARs proved robust and useful during field campaigns at different meteorological conditions. Both lidars show good agreement in validation All mentioned above calculations are done automatically by the integrated internal software and display retrieved results on the front panel of the acquisition system allowing immediate interpretation of wind measurements with very high accuracy. Applied approach proved feasible for quasi-continuous wind profiling. The range of wind profiles obtained with this prototype is between 45-650m with vertical resolution of 15m/30m for integration times of 2Hz in ligne of sight. It is able to measure the wind speed in the range between ±30m/s. An example of radial wind speed profile with corresponding carrier-to-noise ratio are shown in Fig.5 and in Fig.6 result of recent validation with an ultrasonic is shown. In the near future, additionally to the computation of the wind shear, the system will utilise also scanning option for vortex detection. (figure presented) experiments against different aerosol and cloud parameters instrulmentation and wind speed sensors. Hence, both lidars prove to be of great use in order to improve for continuous meteorological and pollution measurements in the future."
"55576500100;7006783796;6701859365;55702592400;7102651635;55262499900;24322892500;35567153700;","Real-time mesoscale forecast support during the CLAMS field campaign",2007,"10.1007/s00376-007-0599-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-38349056803&doi=10.1007%2fs00376-007-0599-3&partnerID=40&md5=0e9a360410ffea64011b347bbd13348e","This paper reports the use of a specialized, mesoscale, numerical weather prediction (NWP) system and a satellite imaging and prediction system that were set up to support the CLAMS (Chesapeake Lighthouse and Aircraft Measurements for Satellites) field campaign during the summer of 2001. The primary objective of CLAMS was to validate satellite-based retrievals of aerosol properties and vertical profiles of the radiative flux, temperature and water vapor. Six research aircraft were deployed to make detailed coincident measurements of the atmosphere and ocean surface with the research satellites that orbited overhead. The mesoscale weather modeling system runs in real-time to provide high spatial and temporal resolution for forecasts that are delivered via the World Wide Web along with a variety of satellite imagery and satellite location predictions. This system is a multi-purpose modeling system capable of both data analysis/assimilation and multi-scale NWP ranging from cloud-scale to larger than regional scale. This is a three-dimensional, nonhydrostatic compressible model in a terrain-following coordinate. The model employs advanced numerical techniques and contains detailed interactive physical processes. The utility of the forecasting system is illustrated throughout the discussion on the impact of the surface-wind forecast on BRDF (Bidirectional Reflectance Distribution Function) and the description of the cloud/moisture forecast versus the aircraft measurement. © Science Press 2007."
"23011324700;23013552100;23013364700;","Land cover classification based on SAR data in Southeast China",2007,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448978331&partnerID=40&md5=9dd5746bb660cbb936fbdf01901cb76b","Southeast China is a sub-tropical area where it is rainy or cloudy for most time of the year. Optical remote sensing data are often unavailable because of the meteorological conditions. SAR becomes the most effective and sometimes the only remote sensing instrument for earth observation in these areas due to its penetration to rain and cloud. This research study presented here focuses on the use of ERS and Envisat-1 SAR data for land cover/land use classification in Fujian province in southeast China. Both SAR backscatter intensity and interferometric coherence were investigated. To overcome the well-known speckle phenomenon, a parcel based approach to information extraction is used for classification by synergistic use of SAR and high spatial resolution optical data. The classification result was validated by field campaign and showed promising application of ESA SAR data in southeast China."
"12141789600;6603764973;7006242396;7101984634;","Validation of satellite derived conus cloud top pressure using cloud physics lidar data from the atrec field campaign",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949288458&partnerID=40&md5=f85f2e3b0bd749d7820d7a2a931958ee",[No abstract available]
"7102084129;6701922947;15318942300;","Aircraft measurements of the impacts of pollution aerosols on clouds and precipitation over the Sierra Nevada",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-75149190998&partnerID=40&md5=687c36cd821528c542c997efb01d5e56","Satellite measurements in onshore-flowing clouds showed that they become more microphysically continental downwind of areas of major emissions of anthropogenic aerosols. Rain gauge analyses of orographic precipitation showed that the upslope precipitation in mountain ranges downwind was decreased with respect to the coastal precipitation during the 20th century along with the assumed increase in pollution aerosols. Following the publication of these findings a research effort called SUPRECIP (Suppression of Precipitation) was conducted to make in situ aircraft measurements of the polluting aerosols, the composition of the clouds ingesting them, and the way the precipitation forming processes are affected. Preliminary results of SUPRECIP Phase 2 2006 are reported here. The program is funded by the PIER (Public Interest Energy Research) Program of the California Energy Commission. The flights documented the aerosols and orographic clouds downwind of the densely populated areas in the central Sierra Nevada and contrasted them with the aerosols and clouds downwind of the sparsely-populated areas in the northern Sierra Nevada. The main results from the February 2005 campaign of SUPRECIP-1 are: 1. The in situ aircraft measurements of the cloud microstructure validated the satellite retrievals of cloud particle effective radius and microphysical phase. 2. Ample supercooled drizzle were found in the pristine orographic clouds with only few tens of drops cm-3, and no drizzle with small concentrations of graupel were found in clouds with drop number concentrations of ∼ 150 cm-3. 3. The pristine clouds occurred in air masses that were apparently decoupled from the boundary layer in the early morning, whereas the more microphysically continental clouds occurred during the afternoon, when the surface inversion over the Central Valley disappeared. Based on what was learned during the first season, a second field campaign was conducted in February and March 2006, called SUPRECIP-2. The cloud physics instruments were enhanced with another cloud drop spectrometer, and a second low level aerosol airplane was added. Two cloud physics aircraft were involved, making measurements of CCN, CN, cloud drop size distribution, hydrometeor images and size distribution, thermodynamic properties of the air and air 3-D winds. SUPRECIP-2 was augmented also by surface measurements of aerosols and chemical composition of the hydrometeors, made by collaborating research groups from the Desert Research Institute of the University of Nevada, The University of California Davis, and the SCRIPPS Oceanographic Institute of the University of California at San Diego. This provided coincident measurements of the low level aerosols and the properties of the clouds that ingest them. Preliminary results, reported here, confirm the link between anthropogenic aerosols and suppressing precipitation forming processes in the clouds in the context of California."
"7006174850;6701873215;6507274020;","Another look at stochastic condensation in clouds: Exact solutions, fokker-planck approximations and adiabatic evolution",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-75149121058&partnerID=40&md5=661d5c2e876b0d8fa1de93496178ddd6","In this manuscript - which closely follows Jeffery et al. (2006) - we have taken ""another look"" at stochastic condensation in the hope of clarifying the earlier derivations and fully exploring the implications of this theory. In contrast to the derivations of Levin and Sedunov (1966a, b) and Manton (1979), we begin with a simple model of stochastic condensation - independent, Gaussian supersaturation fluctuations (S′) renewed after a time τ - that is exactly solvable. This model is trivial to simulate on a computer and can be used to compare and contrast Lagrangian and Eulerian approaches for modeling droplet spectra (Andrejczuk et al. 2006). The Fokker-Planck approximation to this exact solution follows by replacing the discrete sampling of S′ with its continuous surrogate. The Fokker-Planck diffusivity and operator are thus seen to be the natural smooth-in-time approximation to a discrete-in-time process. We have also taken another - look at the equation for the mean supersaturation, S̄FP, in the presence of S′ fluctuations modeled using the Levin-Sedunov-Mazin Fokker-Planck operator. While this problem is treated in an approximate fashion (and with little transparency) in Voloshchukand Sedunov (1977), we derive the expression for (S′|r)FP without approximation and show how this expression ""closes"" the S̄FP-equation self-consistently, thereby ensuring that total water mass is exactly conserved. Using the quasi-stationary (QS) evaluation of S̄FP, we derive the exact correction term to SFP, QS (i.e. the S′ contribution corresponding to the Levin-Sedunov-Mazin model). The correction term is negative definite, peaks in magnitude when (r)r is near the accommodation length (≈ 2 μm), and decays as (r-1)r as the droplet spectrum grows to large sizes. This exact result has a direct correspondence to the analysis of Cooper (1989). Using our self-consistent equation for S̄FP, we evaluate spectral broadening in an adiabatic parcel and find some broadening to larger sizes (consistent with earlier estimates, e.g. Manton (1979)), but a more significant decrease in 〈r2〉 r at fixed liquid water content which may have implications for modeled cloud reflectivity. While the proceeding discussion is largely a clarification and elucidation of previous work, most notably Voloshchuk and Sedunov (1977), we have also extended the theory of stochastic condensation by deriving the non-dimensional number, ND, that determines the relative impact of S′-fluctuations on droplet spectral evolution in an adiabatic volume and in the QS limit. For constant updraft velocity and Fokker-Planck diffusivity, ND is also a constant, ranging from 10-2 to 102 for typical atmospheric conditions and model grid sizes when the assumed S′-standard deviation is 1%. We find significant spectral broadening, and in particular decreasing 〈r2〉r, for ND &gt; 1, and discover that S̄FP, QS can be negative in a rising adiabatic parcel when ND &gt; 6.5 for droplets of zero initial size. Using in-situ droplet spectra from cumulus cloud fields observed during the RICO and SCMS field campaigns, we have verified a seminal prediction of the theory of stochastic condensation - increasing broadening with increasing spatial scale - by averaging the observed spectra over segments containing one or more clouds. In addition, scale-dependent values of ND retrieved from the segment-averaged spectra using our adiabatic model show good consistency with the previously discussed theoretical estimates. We believe this encouraging result to be the first observational confirmation of the stochastic condensation mechanism and the decades-old, pioneering work of Levin-Sedunov-Mazin. Moreover, these results suggest that the parameterization of unresolved S′-fluctuations using Fokker-Planck theory or other means will become increasingly important as explicit (bin) microphysics schemes are applied at larger scales (Lynn et al. 2005), where an increasing fraction of individual clouds are, themselves, unresolved. However, important differences between the observed and modeled droplet spectra are also observed. In particular, the observed spectra suggest non-Gaussian S′ fluctuations and the inhomogeneous mixing process of Baker et al. (1980). Further work is needed to assess the impact of non-Gaussian S′-fluctuations and large renewal times on droplet spectral broadening and to derive differential operators that can model their ensemble effect in the equations of cloud physics."
"6601969764;57215900396;15053050600;12645277800;57217493793;15848759600;6701777429;15751862600;7406741310;15752304700;57206030478;15752092200;15752247900;","EPS meteorological products validation at the valencia anchor station (EPS MET PRO VAS)",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845735032&partnerID=40&md5=2c6d48d097b4a3a208e30b0b8397fd77","The general objective is to validate some EPS/MetOp products taking advantage of the extraordinary conjunction of the Valencia Anchor Station, a reference meteorological station for validation of low spatial resolution remote sensing data and products (http://www.uv.es/anchors/: http://www.uv.es/elopez/) , which is proving to be efficacious in the context of the GERB, CERES and SMOS missions, the suitable application of means, instruments and tools from the Spanish Institute for Meteorology (INM, http://www.inm.es/) over the Valencia Anchor Station area, the recognised expertise of the Institute for Space Studies of Catalonia (IEEC) in GNSS applications on Meteorology and Remote Sensing (http://europa.ieec.fcr.es/english/recerca/gnss/), and the special capability of the CERES (Clouds and the Earth's Radiant Energy System) instrument to perform Programmable Azimuth Plane Scans (PAPS) that enhance the ability to intercalibrate instruments on different spacecraft and to augment the spatial and angular coverage of targeted areas during intensive observation field campaigns specifically designed (See http://asd-www.larc.nasa.gov/PAPS/ CERES_PAPS.html/). From January 2005 a twin reference validation station is also available in the Valencian Region, the Alacant Anchor Station (AAS), at about 150 km from the VAS, with similar land uses to those of the VAS, but placed in a different climate area, of Mediterranean arid conditions, which adds new values to the study. Since the Alacant Anchor Station has been chosen in the objectively most degraded crop area of the Valencian Region, the comparison and monitoring of meteorological parameters and surface fluxes between both stations will allow us to study the interactions between desertification and climate."
"7409792174;","A numerical investigation of a slow-moving convective line in a weakly sheared environment",2005,"10.1007/BF02918706","https://www.scopus.com/inward/record.uri?eid=2-s2.0-26644447969&doi=10.1007%2fBF02918706&partnerID=40&md5=184acfa6ec25c77fc4bb9dcc45228f6b","A series of three-dimensional, cloud-resolving numerical simulations are performed to examine a slow-propagating, quasi-two-dimensional convective system in a weakly sheared environment during the Tropical Rainfall Measuring Mission Large-Scale Biosphere-Atmosphere (TRMM-LBA) field campaign. The focus is on the kinematics and thermodynamics, organization mechanisms, and dynamical effects of low-level shear, ice microphysics and tropospheric humidity. The control simulation, which is initialized with the observed sounding and includes full microphysics, successfully replicates many observed features of the convective system, such as the linear structure, spatial orientation, life cycle, and sluggish translation. The system at the mature stage displays a line-normal structure similar to that associated with squall-type convective systems, but the corresponding mesoscale circulation and thermodynamic modification are much weaker. Ice-phase microphysical processes are not necessary to the formation of the convective system, but they play a non-trivial role in the late evolution stage. In contrast, the low-level shear, albeit shallow and weak, is critical to the realistic realization of the convective line. The tropospheric moisture above the planetary boundary layer has an important impact on the behavior of convective organization. In particular, a dry layer in the lower troposphere significantly suppresses convective development and inhibits the generation of organized convection even though the convective available potential energy is substantial. The free-atmosphere humidity has received little attention in previous studies of organized convection and warrants further investigation."
"6602407753;35547214900;7202108879;7005981420;","Cloud physics lidar optical measurements during the SAFARI-2000 field campaign",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036399478&partnerID=40&md5=b8758913272f4294796e9c591b452982","In this presentation, we will show new optical data processing results from the Cloud Physics Lidar during SAFARI-2000. Retrieved products include aerosol and cloud layer location and identification, layer optical depths, vertical extinction profiles, and extinction-to-backscatter (S) ratios for 532 and 1064 nm. The retrievals will focus on the persistent and smoky planetary boundary layer and occasional elevated aerosol layers found in southern Africa during August and September 2000."
"7007115297;7102001985;7004508111;","An analysis of atmospheric nitrate sulfate levels and particle number concentration in the North Atlantic sub-tropical region",2000,"10.1016/s0021-8502(00)90555-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034271722&doi=10.1016%2fs0021-8502%2800%2990555-x&partnerID=40&md5=deb6dbd07cc68a1698e8a3889807eb16",[No abstract available]
"57201124395;7004494327;55925779800;6603221134;","Ion composition of cloud processed continental aerosol particles",2000,"10.1016/s0021-8502(00)90071-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034271516&doi=10.1016%2fs0021-8502%2800%2990071-5&partnerID=40&md5=3187d13a0d395b67c71b7c4d9f60dfbc",[No abstract available]
"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]
"7004884101;55675223176;7406215388;7402074810;7005490049;7006874359;6701653010;","Use of Doppler radar profilers as a calibration tool in support of TRMM ground validation field campaigns",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032669712&partnerID=40&md5=df401ce8e1b4c9d03132c6f9b7cf8c0d","The Tropical Rainfall Measuring Mission (TRMM) is aimed at improved measurement of precipitation from space in order to achieve a more precise estimate of the diabatic heating associated with tropical precipitating cloud systems. As part of this effort, profiler observations of hydrometeors in precipitating cloud systems have been taken during several Ground Validation field campaigns. Measurements with co-located Joss distrometer show that reflectivities observed at the lowest reliable heights of the profiler track the calculated reflectivities deduced from the Joss disdrometer."
"7006874359;6601975516;7202957110;7406215388;56691869300;7004884101;","Wind profiler retrieved hydrometeor size distributions in the mixed phase region of precipitating clouds: Initial approach and comparison of dual-polarimetric radar measurements",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031360924&partnerID=40&md5=2d8447faceb6283feffbbd3057af9e14","A vertically pointing wind profiler and dual-polarimetric scanning radar data is used to investigate the microphysical processes occurring within the mixed phase region from several precipitation events in north east Colorado. The data were collected during a 1996 summer field campaign. Both the CHILL S-band radar, located near Greeley, CO, and the NCAR S-Pol radar, located at Front Range airport, provide aerial coverage over co-located 50 and 915 MHz profilers at Platteville, CO. A spectra-fitting algorithm is used to retrieved both the vertical air motions and the hydrometeor size distribution parameters from the profiler data. The ability of wind profilers to accurately retrieve hydrometeor size distributions in rain has been well documented."
"35419152500;7003911760;7003729315;35516146500;","Scanning Raman lidar to measure atmospheric water vapor and aerosols",1995,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029217366&partnerID=40&md5=a9cd9c1d6e0956bf8456e7c9e9adc524","Raman lidar is an effective tool for measuring the vertical and temporal evolution of atmospheric water vapor and aerosols. The NASA/GSFC Scanning Raman Lidar (SRL), in particular, has participated in several coordinated field campaigns since its first operation in 1991. To illustrate this further, measurement capabilities of the SRL are discussed and representative data are presented."
"7005228425;","The Po Valley Fog Experiment 1989What have we learned, where do we go from here?",1992,"10.1034/j.1600-0889.1991.t01-3-00002.x-i1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982683371&doi=10.1034%2fj.1600-0889.1991.t01-3-00002.x-i1&partnerID=40&md5=df5d81e9ccb3c6a3920a33babe494fb8","In this special issue of Tellus B, results of the first of a series of joint European field campaigns concerning ground‐base cloud experiments (GCE) are reported. The present paper illuminates the background of the experiment before giving answers to the questions of what GCE did achieve in the Po Valley experiment, what lessons have been learned on the way and where ground‐based cloud research does go from there. Copyright © 1992, Wiley Blackwell. All rights reserved"
"7407413546;7003630909;57188974903;35876367800;7007124673;7003970460;6603646574;","SAYANI'91: A joint United States / commonwealth of independent states field campaign to investigate forest decline damage in the Krasnoyarsk region of Southcentral Siberia",1992,"10.1109/IGARSS.1992.578423","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964491321&doi=10.1109%2fIGARSS.1992.578423&partnerID=40&md5=f19028ff602a31399d74894547560509","Under the auspices of the NASA/INTERCOSMOS Bilateral Agreement, a group of five American scientists visited the Commonwealth of Independent States (formerly the USSR) from August 4th through August 20th 1991 to participate in the Russian field campaign known as ""SAYANI'91."" This field experiment took place in the Sayani Mountains located in the southern Krasnoyarsk region of Siberia. The approximate centerpoint coordinates of the study area are 53°N / 93°E, some 450 km north of the western Mongolian border, and 1500 km west of the Lake Baikal region. The purpose of the joint field campaign was to observe and exchange methodologies with Russian scientists with regard to the development of remote sensing techniques for the early detection and assessment of forest decline damage believed to be associated with atmospheric deposition and/or insect and disease infestations. Participants consisted of the five American scientists, and Russian scientists representing (a) the Sukachev Institute of Forest and Wood, an Academy of Sciences facility located in Krasnoyarsk, Siberia, (b) the Department of Aerial and Space Methods within the State Forest Committee in Moscow, as well as (c) two additional institutions known as Goskomles and IEMEZ, both of which are also located in Moscow. Using a combination of both Russian and American instruments, several types of passive and active remote sensing measurements were made in conjunction with biophysical measurements on vegetative samples collected from four study sites representing a strong elevational gradient. The tree species studied were Siberian fir, Abies siberica, and Siberian pine, Pinus siberica (which the locals refer to as a cedar). Relatively cloud-free SPOT data were also acquired over the Sayani Mountain study area on August 11th1992 (i.e., during the field campaign). Additional background information, as well as more in-depth discussions of objectives, site characteristics, and mensuration activities will be summarized in the remainder of this paper. More specific details of the measurements that were made, as well as the results that have been attained, will be provided in accompanying papers by Ranson et al.(Paper #492) and Rock et al.(Paper #493). © IEEE 1992."