MODerate resolution Imaging Spectroradiometer (MODIS) cryosphere products have been available since 2000-following the 1999 launch of the Terra MODIS and the 2002 launch of the Aqua MODIS-and include global snow-cover extent (SCE) (swath, daily, and 8 d composites) at 500 m and ĝ1/45 km spatial resolutions. These products are used extensively in hydrological modeling and climate studies. Reprocessing of the complete snow-cover data record, from Collection 5 (C5) to Collection 6 (C6) and Collection 6.1 (C6.1), has provided improvements in the MODIS product suite. Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Collection 1 (C1) snow-cover products at a 375 m spatial resolution have been available since 2011 and are currently being reprocessed for Collection 2 (C2). Both the MODIS C6.1 and the VIIRS C2 products will be available for download from the National Snow and Ice Data Center beginning in early 2020 with the complete time series available in 2020. To address the need for a cloud-reduced or cloud-free daily SCE product for both MODIS and VIIRS, a daily cloud-gap-filled (CGF) snow-cover algorithm was developed for MODIS C6.1 and VIIRS C2 processing. MOD10A1F (Terra) and MYD10A1F (Aqua) are daily, 500 m resolution CGF SCE map products from MODIS. VNP10A1F is the daily, 375 m resolution CGF SCE map product from VIIRS. These CGF products include quality-Assurance data such as cloud-persistence statistics showing the age of the observation in each pixel. The objective of this paper is to introduce the new MODIS and VIIRS standard CGF daily SCE products and to provide a preliminary evaluation of uncertainties in the gap-filling methodology so that the products can be used as the basis for a moderate-resolution Earth science data record (ESDR) of SCE. Time series of the MODIS and VIIRS CGF products have been developed and evaluated at selected study sites in the US and southern Canada. Observed differences, although small, are largely attributed to cloud masking and differences in the time of day of image acquisition. A nearly 3-month time-series comparison of Terra MODIS and S-NPP VIIRS CGF snow-cover maps for a large study area covering all or parts of 11 states in the western US and part of southwestern Canada reveals excellent correspondence between the Terra MODIS and S-NPP VIIRS products, with a mean difference of 11 070 km2, which is ĝ1/40.45 % of the study area. According to our preliminary validation of the Terra and Aqua MODIS CGF SCE products in the western US study area, we found higher accuracy of the Terra product compared with the Aqua product. The MODIS CGF SCE data record beginning in 2000 has been extended into the VIIRS era, which should last at least through the early 2030s.
. © 2019 BMJ Publishing Group. All rights reserved." "57208683395;10040318500;23095483400;57203053317;57212574325;57212571057;25522357400;","Impact of isolated atmospheric aging processes on the cloud condensation nuclei activation of soot particles",2019,"10.5194/acp-19-15545-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077125743&doi=10.5194%2facp-19-15545-2019&partnerID=40&md5=e24de9bc157c486b8e03f1891cee48f7","The largest contributors to the uncertainty in assessing the anthropogenic contribution in radiative forcing are the direct and indirect effects of aerosol particles on the Earth's radiative budget. Soot particles are of special interest since their properties can change significantly due to aging processes once they are emitted into the atmosphere. Probably the largest obstacle for the investigation of these processes in the laboratory is the long atmospheric lifetime of 1 week, requiring tailored experiments that cover this time span. This work presents results on the ability of two types of soot, obtained using a miniCAST soot generator, to act as cloud condensation nuclei (CCN) after exposure to atmospherically relevant levels of ozone (O3) and humidity. Aging times of up to 12 h were achieved by successful application of the continuous-flow stirred tank reactor (CSTR) concept while allowing for size selection of particles prior to the aging step. Particles of 100 nm diameter and rich in organic carbon (OC) that were initially CCN inactive showed significant CCN activity at supersaturations (SS) down to 0.3 % after 10 h of exposure to 200 ppb of O3. While this process was not affected by different levels of relative humidity in the range of 5 %-75 %, a high sensitivity towards the ambient/reaction temperature was observed. Soot particles with a lower OC content required an approximately 4-fold longer aging duration to show CCN activity at the same SS. Prior to the slow change in the CCN activity, a rapid increase in the particle diameter was detected which occurred within several minutes. This study highlights the applicability of the CSTR approach for the simulation of atmospheric aging processes, as aging durations beyond 12 h can be achieved in comparably small aerosol chamber volumes (< 3 m3). Implementation of our measurement results in a global aerosol-climate model, ECHAM6.3-HAM2.3, showed a statistically significant increase in the regional and global CCN burden and cloud droplet number concentration. © 2019 Author(s)." "35227762400;55173596300;35611334800;15755995900;24757696000;6602600408;","Separating radiative forcing by aerosol-cloud interactions and rapid cloud adjustments in the ECHAM-HAMMOZ aerosol-climate model using the method of partial radiative perturbations",2019,"10.5194/acp-19-15415-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076677100&doi=10.5194%2facp-19-15415-2019&partnerID=40&md5=9298b28c74684157b00df0d160cc7040","Using the method of offline radiative transfer modeling within the partial radiative perturbation (PRP) approach, the effective radiative forcing by aerosol-cloud interactions (ERFaci) in the ECHAM-HAMMOZ aerosol climate model is decomposed into a radiative forcing by anthropogenic cloud droplet number change and adjustments of the liquid water path and cloud fraction. The simulated radiative forcing by anthropogenic cloud droplet number change and liquid water path adjustment are of approximately equal magnitude at-0:52 and-0:53Wm-2, respectively, while the cloud-fraction adjustment is somewhat weaker at-0:31Wm-2 (constituting 38 %, 39 %, and 23% of the total ERFaci, respectively); geographically, all three ERFaci components in the simulation peak over China, the subtropical eastern ocean boundaries, the northern Atlantic and Pacific oceans, Europe, and eastern North America (in order of prominence). Spatial correlations indicate that the temporal-mean liquid water path adjustment is proportional to the temporal-mean radiative forcing, while the relationship between cloud-fraction adjustment and radiative forcing is less direct. While the estimate of warm-cloud ERFaci is relatively insensitive to the treatment of ice and mixedphase cloud overlying warm cloud, there are indications that more restrictive treatments of ice in the column result in a low bias in the estimated magnitude of the liquid water path adjustment and a high bias in the estimated magnitude of the droplet number forcing. Since the present work is the first PRP decomposition of the aerosol effective radiative forcing into radiative forcing and rapid cloud adjustments, idealized experiments are conducted to provide evidence that the PRP results are accurate. The experiments show that using low-frequency (daily or monthly) time-averaged model output of the cloud property fields underestimates the ERF, but 3-hourly mean output is sufficiently frequent. © 2019 Copernicus GmbH. All rights reserved." "55225894400;24381474400;57191172390;57211565887;25652188900;57213046638;7004587644;56250119900;35782476600;57212530468;57192180109;","The sensitivity of Southern Ocean aerosols and cloud microphysics to sea spray and sulfate aerosol production in the HadGEM3-GA7.1 chemistry-climate model",2019,"10.5194/acp-19-15447-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076945970&doi=10.5194%2facp-19-15447-2019&partnerID=40&md5=70a9096cb029a3f145cc8bcdbf53b65c","With low concentrations of tropospheric aerosol, the Southern Ocean offers a ""natural laboratory"" for studies of aerosol-cloud interactions. Aerosols over the Southern Ocean are produced from biogenic activity in the ocean, which generates sulfate aerosol via dimethylsulfide (DMS) oxidation, and from strong winds and waves that lead to bubble bursting and sea spray emission. Here, we evaluate the representation of Southern Ocean aerosols in the Hadley Centre Global Environmental Model version 3, Global Atmosphere 7.1 (HadGEM3-GA7.1) chemistry-climate model. Compared with aerosol optical depth (AOD) observations from two satellite instruments (the Moderate Resolution Imaging Spectroradiometer, MODIS-Aqua c6.1, and the Multi-angle Imaging Spectroradiometer, MISR), the model simulates too-high AOD during winter and too-low AOD during summer. By switching off DMS emission in the model, we show that sea spray aerosol is the dominant contributor to AOD during winter. In turn, the simulated sea spray aerosol flux depends on near-surface wind speed. By examining MODIS AOD as a function of wind speed from the ERA-Interim reanalysis and comparing it with the model, we show that the sea spray aerosol source function in HadGEM3-GA7.1 overestimates the wind speed dependency. We test a recently developed sea spray aerosol source function derived from measurements made on a Southern Ocean research voyage in 2018. In this source function, the wind speed dependency of the sea spray aerosol flux is less than in the formulation currently implemented in HadGEM3-GA7.1. The new source function leads to good agreement between simulated and observed wintertime AODs over the Southern Ocean; however, it reveals partially compensating errors in DMS-derived AOD. While previous work has tested assumptions regarding the seawater climatology or sea-air flux of DMS, we test the sensitivity of simulated AOD, cloud condensation nuclei and cloud droplet number concentration to three atmospheric sulfate chemistry schemes. The first scheme adds DMS oxidation by halogens and the other two test a recently developed sulfate chemistry scheme for the marine troposphere; one tests gas-phase chemistry only, while the second adds extra aqueous-phase sulfate reactions. We show how simulated sulfur dioxide and sulfuric acid profiles over the Southern Ocean change as a result and how the number concentration and particle size of the soluble Aitken, accumulation and coarse aerosol modes are affected. The new DMS chemistry scheme leads to a 20 % increase in the number concentration of cloud condensation nuclei and cloud droplets, which improves agreement with observations. Our results highlight the importance of atmospheric chemistry for simulating aerosols and clouds accurately over the Southern Ocean. © Author(s) 2019." "6507442204;17339825900;7004406545;","Assessment of cloudiness for use in environmental marine research",2019,"10.1080/01431161.2019.1633697","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068217783&doi=10.1080%2f01431161.2019.1633697&partnerID=40&md5=0fe48c902c663a661b4b2a2637168c07","A very simple algorithm with which to assess cloudiness over the Baltic Sea has been developed. The algorithm involves analysis of cloud longwave emissivity, supplemented with available information on shortwave emissions. The simple classification method is based on the split-window technique and compares a signal recorded in the neighbouring spectral bands with results of cloud-free atmosphere modelling. The algorithm was tested using data from the SEVIRI (Spinning Enhanced Visible and InfraRed Imager) satellite radiometer, but the method can be easily implemented for other data sources. Compatibility with instant shipborne radiation measurements was obtained. The effectiveness of the comparison was determined from the Hanssen–Kuiper score. The CM SAF (Satellite Application Facility on Climate Monitoring) data comparison shows that the system correctly classified areas in 88%, the satellite map accuracy was 46% with a 54% overvaluation error. The accuracy of the detection system was 44%, and the underestimation error was 56%. The comparison of modelling results showed 71% of correctly classified areas, the accuracy of the satellite map was 35%, and the repricing error was 65%. The accuracy of the detection system was 36%, and the underestimation error was 64%. The concordance of satellite measurements (Cohen’s kappa coefficient) was at a level of 98% and 99% between the satellite and model. Statistically, the analysis is based on the results of measurements for the Baltic Sea basin in 2015. The obtained data on the monthly cloudiness was compared with the operational, model and lidar data. A difference between the solution proposed and the approaches derived from prognostic models is demonstrated. The regional scale solution is shown to be a better representation of the true state of the atmosphere, compared to global-scale models. The results obtained show cloudiness assessments to differ depending on the model applied (CM SAF, UMPL–Unifed Model for Poland). The average annual cloudiness of the Baltic Sea is around 58.5%. It is a repeatable value by other solutions based on various methods and sources (MODIS–Moderate Resolution Imaging Spectroradiometer), including lidar ones (CALIPSO–Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation). In addition, a potential for applying the regional cloudiness assessment to estimate the top-down components of the radiation budget is illustrated. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group." "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." "57194590834;7402739568;55924208000;","The Impact of a Stochastic Parameterization Scheme on Climate Sensitivity in EC-Earth",2019,"10.1029/2019JD030732","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076357138&doi=10.1029%2f2019JD030732&partnerID=40&md5=128b3a5f8fb4ecae980472d27b16d0c7","Stochastic schemes, designed to represent unresolved subgrid-scale variability, are frequently used in short and medium-range weather forecasts, where they are found to improve several aspects of the model. In recent years, the impact of stochastic physics has also been found to be beneficial for the model's long-term climate. In this paper, we demonstrate for the first time that the inclusion of a stochastic physics scheme can notably affect a model's projection of global warming, as well as its historical climatological global temperature. Specifically, we find that when including the “stochastically perturbed parametrization tendencies” (SPPT) scheme in the fully coupled climate model EC-Earth v3.1, the predicted level of global warming between 1850 and 2100 is reduced by 10% under an RCP8.5 forcing scenario. We link this reduction in climate sensitivity to a change in the cloud feedbacks with SPPT. In particular, the scheme appears to reduce the positive low cloud cover feedback and increase the negative cloud optical feedback. A key role is played by a robust, rapid increase in cloud liquid water with SPPT, which we speculate is due to the scheme's nonlinear interaction with condensation. ©2019. The Authors." "45661599100;7402425067;55965925000;16403404400;53878006900;7401934994;","Inequal Responses of Drylands to Radiative Forcing Geoengineering Methods",2019,"10.1029/2019GL084210","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076086859&doi=10.1029%2f2019GL084210&partnerID=40&md5=7f23ced5873a6af72d0d1593009768c0","Climate geoengineering has the potential to reduce global warming. However, the nonlinear responses of Earth's large-scale circulation to climate geoengineering can exacerbate regional climate change, with potential inequality risks. We show noticeable inequality in the responses of drylands when three radiative forcing geoengineering (RFG) methodologies—cirrus cloud thinning (CCT), marine sky brightening (MSB), and stratospheric aerosol injection (SAI)—individually reduce the radiative forcing of the representative concentration pathway 8.5 scenario using a set of the Norwegian Earth system model (NorESM1-ME) experiments. In North America, CCT and SAI alleviate drylands expansion, whereas drylands expand further under MSB. CCT induces significantly wetter conditions over the western Sahel. Wetting over Australia is enhanced and prevented by MSB and SAI, respectively. Our results suggest spatially inequal distributions of benefits and harms of individual RFGs on the projected distribution of drylands, which should be considered before any real-world application of such RFGs. ©2019. The Authors." "56724051400;8686475900;57194589938;57212168740;6603148342;6603729223;8505489500;","Impact of Future Warming and Enhanced [CO2] on the Vegetation-Cloud Interaction",2019,"10.1029/2019JD030717","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076107331&doi=10.1029%2f2019JD030717&partnerID=40&md5=9c68f4d6a395cf98eb4e836636dc01fc","The effects of increases in carbon dioxide and temperature on the vegetation-atmosphere-cloud interaction are studied with a bottom-up approach. Using the 3-D large-eddy simulation technique coupled with a CO2-sensitive dynamic plant physiological submodel, we aimed to spatially and temporally understand the surface and vegetation forcing on the coupled land-atmosphere interactions in future scenarios. Four simulations were designed: a control simulation for current conditions, an enhanced carbon dioxide simulation (current +200 ppm), an elevated temperature simulation (current +2 K), and a simulation covering the combination of both elevations in temperature and CO2. With elevations in carbon dioxide, plant transpiration is reduced due to stomatal closure, resulting in reduced latent- and increased sensible heat fluxes. Although no effects on cloud cover were found in this simulation, the in-cloud moisture flux was enhanced. Elevations in temperature yielded opposite results with reduced sensible and increased latent heat fluxes, which reduced the turbulent kinetic energy and buoyancy rates, thereby negatively impacting cloud formation. Our future climate mimicking simulation shows minimal changes in the regional energy balance due to offsetting effects between increased temperature and [CO2], while plant photosynthesis increased and transpiration decreased. The atmospheric boundary layer was drier, even though surface fluxes were very similar current conditions, thereby hampering cloud formation and development. Our results highlight the necessity of small scales and interactions, which require a bottom-up approach to be able to accurately capture the nonlinear plant-atmosphere interactions. ©2019. American Geophysical Union. All Rights Reserved." "57191860794;7003548068;55450672000;","Transition Zone Radiative Effects in Shortwave Radiation Parameterizations: Case of Weather Research and Forecasting Model",2019,"10.1029/2019JD031064","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076090281&doi=10.1029%2f2019JD031064&partnerID=40&md5=b674b821523811b3ae621171b53f175c","A number of studies have stated that the shift from a cloud-free to cloudy atmosphere (and vice versa) contains an additional phase, named “Transition (or twilight) Zone”. However, the information available about radiative effects of this phase is very limited. Consequently, in most meteorological and climate studies, the area corresponding to the transition zone is considered as an area containing aerosol or optically thin clouds. This study investigates the differences in shortwave radiative effects driven from different treatments of the transition zone. To this aim, three of the shortwave radiation parameterizations (NewGoddard, Rapid Radiative Transfer Model for Global circulation models, and Fu-Liou-Gu) included in the Advanced Research Weather Research and Forecasting Model (WRF-ARW) were isolated and adapted for one-dimensional vertical simulations. These parameterizations were then utilized to perform simulations under ideal “cloud” and “aerosol” modes, for different values of (i) cloud optical depths resulting from different sizes of ice crystals or liquid droplets and mixing ratios; and (ii) different aerosol optical depths combined with various aerosol types. The resulting shortwave broadband total, direct, and diffuse irradiances at the Earth surface were analyzed. The uncertainties originated from different assumptions of a situation regarding to the transition zone are quite substantial for all the parameterizations. For all the parameterizations, direct and total irradiances are the least and most sensitive irradiances to different treatments of the transition zone, respectively. Differences in the radiative effects of transition zone dominantly result from the difference between the radiative effects of clouds and aerosols (different types), not from cloud type or droplet/crystal size. ©2019. American Geophysical Union. All Rights Reserved." "16242417100;22236015300;","Validation of Microphysical Snow Models Using In Situ, Multifrequency, and Dual-Polarization Radar Measurements in Finland",2019,"10.1029/2019JD030721","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076350136&doi=10.1029%2f2019JD030721&partnerID=40&md5=9ec138832e849f798b2c0c70818bd624","As complex forward models for snow have become common in radar-based retrievals, there is a demand to validate these models in different environments. In this study, we perform a qualitative, general validation for nine different snow models that have been published and are available to users. The chosen models span a variety of different snow types, such as aggregates, rimed aggregates, melted aggregates, graupel, and single crystals, mainly because these particles are commonly observed in the Finnish climate. Fitted power law formulas for mass, fall velocity, aspect ratio, and area ratio are compared between the models and 5-year winter measurements in the Hyytiälä forestry field station in Finland. We also compare the backscattering properties of the models to triple-frequency dual-polarization radar measurements during the Biogenic Aerosols Effects on Clouds and Climate campaign in 2014. We find that the denser models, regardless of the exact shapes, fit the in situ measurements best due to the prevalence of rime in the falling snow. However, when comparing also to the triple-frequency radar measurements at X, Ka, and W bands, and the linear depolarization ratio at Ka band, the physical snow models fit overall better than the empirical ones. ©2019. American Geophysical Union. All Rights Reserved." "7004337213;6602589744;7004715270;7003865921;","Progress and Challenges in Quantifying Wildfire Smoke Emissions, Their Properties, Transport, and Atmospheric Impacts",2019,"10.1029/2018JD029878","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076725514&doi=10.1029%2f2018JD029878&partnerID=40&md5=90e12a5e0238d0dff8d550cd715f5c4c","Wildfire is a natural and integral ecosystem process that is necessary to maintain species composition, structure, and ecosystem function. Extreme fires have been increasing over the last decades, which have a substantial impact on air quality, human health, the environment, and climate systems. Smoke aerosols can be transported over large distances, acting as pollutants that affect adjacent and distant downwind communities and environments. Fire emissions are a complicated mixture of trace gases and aerosols, many of which are short-lived and chemically reactive, and this mixture affects atmospheric composition in complex ways that are not completely understood. We present a review of the current state of knowledge of smoke aerosol emissions originating from wildfires. Satellite observations, from both passive and active instruments, are critical to providing the ability to view the large-scale influence of fire, smoke, and their impacts. Progress in the development of fire emission estimates to regional and global chemical transport models has advanced, although significant challenges remain, such as connecting ecosystems and fuels burned with dependent atmospheric chemistry. Knowledge of the impact of smoke on radiation, clouds, and precipitation has progressed and is an essential topical research area. However, current measurements and parameterizations are not adequate to describe the impacts on clouds of smoke particles (e.g., CNN, INP) from fire emissions in the range of representative environmental conditions necessary to advance science or modeling. We conclude by providing recommendations to the community that we believe will advance the science and understanding of the impact of fire smoke emissions on human and environmental health, as well as feedback with climate systems. ©2019. American Geophysical Union. All Rights Reserved." "57194698592;15724418700;43860918700;","Ozone Transport-Radiation Feedbacks in the Tropical Tropopause Layer",2019,"10.1029/2019GL084679","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076834069&doi=10.1029%2f2019GL084679&partnerID=40&md5=b98d718490c2c28336bde69038fd9ca8","The tropical tropopause layer (TTL) temperature balance is of considerable interest for its control over the amount of water entering the stratosphere. The upwelling branch of the Brewer-Dobson circulation (BDC) directly affects these temperatures through adiabatic cooling. BDC upwelling also indirectly affects TTL temperatures through the influence of ozone transport on radiative heating. We investigate this latter feedback using a single-column radiative-convective equilibrium model coupled with a model of simplified stratospheric ozone chemistry and vertical transport. We find that BDC ozone transport is of first-order importance for TTL temperatures. Additionally, we estimate the effect of ozone transport on cold point tropopause temperature responses to changes in upwelling. We find that the feedback is responsible for approximately 20% of the response to perturbations on time scales longer than about half a year but that this contribution can be neglected for time scales shorter than about a week. ©2019. American Geophysical Union. All Rights Reserved." "57210559075;","Modeling rainfall interception components of forests: Extending drip equations",2019,"10.1016/j.agrformet.2019.107704","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070888797&doi=10.1016%2fj.agrformet.2019.107704&partnerID=40&md5=a21f180568767bc04955995b5d608813","Assessment of forest interception, I, and its components; the average evaporation rate during the storm, E¯, and canopy storage, S, are essential for simulating the contribution of forests to the water cycle and the climate system. The objectives of this study were to: (i) propose a new model to predict I, E¯, and S, as well as rainfall duration, RD and rainfall intensity, R¯; (ii) correlate E¯, RD, and R¯ assessments; and (iii) quantify the role plant surfaces play on the generation of interception from four forests in Mexico. Based on extended drip equations, the model was calibrated using field measurements from forty-five forest interception case studies (N = case studies, n = number of rains) in tropical dry, TDF (N = 21, n = 347), arid/semi-arid, A&SF (N = 15, n = 659), temperate, TF (N = 4, n = 258), and tropical montane cloud, TMCF, forests (N = 6, n = 658) and validated using field measurements from sprinkling experiments in ne Mexico. The model performed very good in predicting both individual and cumulative I values, with average errors, ME%, as a function of precipitation, P, smaller than 4% and Nash-Sutcliffe, NSE, values > 0.33 for three out of four forests. E¯ assessments accounted for between 65% and 93% of I in these forests. Higher E¯ and I figures were found in individual trees (3.78A mm h−1, 27%) in contrast to forest plots (2.24B mm h−1, 14%). E¯ assessments decreased as a function of RD but increased as a function of R¯ for all forests (p ≤ 0.05). Leaf area index, LAI, significantly explained part of the I variance in complex non-linear fashions (p ≤ 0.05). The novel independent assessments of I, E¯, S, RD, and R¯, the significant relationships between I components, and the complex role plant surfaces play on the generation of I fill an important scientific gap in this area of forest hydrology. © 2019 Elsevier B.V." "41660929500;15032360100;24773909400;","Towards monitoring groundwater-dependent ecosystems using synthetic aperture radar imagery",2019,"10.1002/hyp.13570","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075169217&doi=10.1002%2fhyp.13570&partnerID=40&md5=0cc8598a6a255a8528e28ce2ed7a5ddc","Mapping of groundwater-dependent ecosystems (GDEs) relies largely on assumption-laden evaporation models, and few global, direct, and real-time monitoring techniques exist. We propose a new synthetic aperture radar imagery-derived index, SARGDE, to identify and monitor these ecosystems across Australia. The index captures vegetation reliance on groundwater during dry periods by estimating the relative stability of foliage and branch structure from the vertical/horizontal cross-polarized band and InSAR coherence. SARGDE is tested over two contrasting study sites in Australia. To build and verify the index, a total of 90 Sentinel-1 interferometric wide images are processed and stacked in two data-cubes. GDE response to the SAR signal is explored using a non-linear dimension reduction algorithm. Relevant statistical parameters are derived from data-cubes and combined to form the index. As the index relies on a 1-year time series of globally, freely available, and cloud-insensitive SAR imagery, SARGDE offers unprecedented capabilities for large-scale, annual monitoring of GDEs. Such monitoring will aid reconciliation of human and ecosystem groundwater needs by acting as a systematic monitoring tool, helping policy makers to assure ecosystem sustainability where impacts related to mining, agriculture, or climate change may occur. © 2019 The Authors Hydrological Processes Published by John Wiley & Sons Ltd" "26433044800;57211239541;24554125000;7003521998;57199994542;","Tropospheric fate of allyl cyanide (CH2[dbnd]CHCH2CN): Kinetics, reaction products and secondary organic aerosol formation",2019,"10.1016/j.atmosenv.2019.117041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073101305&doi=10.1016%2fj.atmosenv.2019.117041&partnerID=40&md5=b64dc0e0b45fba3c799b4f7a1adff480","Allyl cyanide, CH2[dbnd]CHCH2CN, is a volatile organic compound that is emitted by biogenic and anthropogenic sources. Daytime atmospheric degradation of CH2[dbnd]CHCH2CN may be initiated by reaction with OH radicals, Cl atoms and O3. In this work, we report the gas-phase rate coefficients for the reaction of these atmospheric oxidants with CH2[dbnd]CHCH2CN (k1, k2 and k3, respectively) determined in an atmospheric simulation chamber at 298 ± 2 K and 760 ± 5 Torr of air, in a NOx-free environment. A relative kinetic method was employed for OH and Cl kinetic studies, obtaining k1 = (1.58 ± 0.39) × 10−11 cm3 molecule−1 s−1 and k2 = (2.26 ± 0.30) × 10−10 cm3 molecule−1 s−1. For the O3+CH2[dbnd]CHCH2CN reaction, k3 = (6.01 ± 0.24) × 10−19 cm3 molecule−1 s−1 was obtained using an absolute kinetic method under pseudo-first order conditions (excess of allyl cyanide). In both cases, Fourier Transform Infrared (FTIR) spectroscopy was used for monitoring the loss of CH2[dbnd]CHCH2CN relative to the loss of a reference compound and the loss of ozone, respectively. The estimated tropospheric lifetime considering all the homogeneous processes evaluated in this work is 16 h, with the major degradation route being the reaction with OH radicals. Gas-phase products detected in the IR spectrum have been identified by comparison with IR experimental spectra and/or theoretical spectra computed using density functional theory (DFT) calculations. In the Cl and O3 reactions, among others, HC(O)CN, HC(O)CH2CN, HC(O)H, and CO were identified as products, indicating that these reactions proceed mainly by addition of the oxidant to the double bond of CH2[dbnd]CHCH2CN. Even though allyl cyanide absorbs in the atmospheric IR window, due to its short lifetime it has a negligible contribution to the radiative forcing of climate. The formation of secondary organic aerosols (SOAs) has been investigated in the Cl reaction by a Fast Particle Mobility Sizer spectrometer. The determined SOA yield is lower than 6%, which could indicate a negligible impact on human health that could also be extrapolated to the OH reaction. © 2019 Elsevier Ltd" "54885784100;10042470700;35301550500;57188628141;7004807312;","Climate system response to stratospheric sulfate aerosols: Sensitivity to altitude of aerosol layer",2019,"10.5194/esd-10-885-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076907853&doi=10.5194%2fesd-10-885-2019&partnerID=40&md5=eda7296b3a78f292d8bef5258ceb0c9d","Reduction of surface temperatures of the planet by injecting sulfate aerosols in the stratosphere has been suggested as an option to reduce the amount of human-induced climate warming. Several previous studies have shown that for a specified amount of injection, aerosols injected at a higher altitude in the stratosphere would produce more cooling because aerosol sedimentation would take longer. In this study, we isolate and assess the sensitivity of stratospheric aerosol radiative forcing and the resulting climate change to the altitude of the aerosol layer. We study this by prescribing a specified amount of sulfate aerosols, of a size typical of what is produced by volcanoes, distributed uniformly at different levels in the stratosphere. We find that stratospheric sulfate aerosols are more effective in cooling climate when they reside higher in the stratosphere. We explain this sensitivity in terms of effective radiative forcing: volcanic aerosols heat the stratospheric layers where they reside, altering stratospheric water vapor content, tropospheric stability, and clouds, and consequently the effective radiative forcing. We show that the magnitude of the effective radiative forcing is larger when aerosols are prescribed at higher altitudes and the differences in radiative forcing due to fast adjustment processes can account for a substantial part of the dependence of the amount of cooling on aerosol altitude. These altitude effects would be additional to dependences on aerosol microphysics, transport, and sedimentation, which are outside the scope of this study. The cooling effectiveness of stratospheric sulfate aerosols likely increases with the altitude of the aerosol layer both because aerosols higher in the stratosphere have larger effective radiative forcing and because they have higher stratospheric residence time; these two effects are likely to be of comparable importance. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License." "57212605841;57208554661;7101683662;","Historical modelling of changes in Lake Erken thermal conditions",2019,"10.5194/hess-23-5001-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077217993&doi=10.5194%2fhess-23-5001-2019&partnerID=40&md5=be49607b94482101ff77fcf114d39e9c","Historical lake water temperature records are a valuable source of information to assess the influence of climate change on lake thermal structure. However, in most cases such records span a short period of time and/or are incomplete, providing a less credible assessment of change. In this study, the hydrodynamic GOTM (General Ocean Turbulence Model, a hydrodynamic model configured in lake mode) was used to reconstruct daily profiles of water temperature in Lake Erken (Sweden) over the period 1961- 2017 using seven climatic parameters as forcing data: wind speed (WS), air temperature (Air T ), atmospheric pressure (Air P), relative humidity (RH), cloud cover (CC), precipitation (DP), and shortwave radiation (SWR). The model was calibrated against observed water temperature data collected during the study interval, and the calibrated model revealed a good match between modelled and observed temperature (RMSE = 1:089 °C). From the long-Term simulations of water temperature, this study focused on detecting possible trends in water temperature over the entire study interval 1961-2017 and in the sub-intervals 1961-1988 and 1989-2017, since an abrupt change in air temperature was detected in 1988. The analysis of the simulated temperature showed that epilimnetic temperature increased on average by 0.444 and 0.792 °C per decade in spring and autumn in the sub-interval 1989-2017. Summer epilimnetic temperature increased by 0.351 °C per decade over the entire interval 1961-2017. Hypolimnetic temperature increased significantly in spring over the entire interval 1961-2017, by 0.148 and by 0.816 °C per decade in autumn in the subinterval 1989-2016. Whole-lake temperature showed a significant increasing trend in the sub-interval 1989-2017 during spring (0.404 °C per decade) and autumn (0.789 °C per decade, interval 1989-2016), while a significant trend was detected in summer over the entire study interval 1961- 2017 (0.239 °C per decade). Moreover, this study showed that changes in the phenology of thermal stratification have occurred over the 57-year period of study. Since 1961, the stability of stratification (Schmidt stability) has increased by 5.365 Jm-2 per decade. The duration of thermal stratification has increased by 7.297 d per decade, corresponding to an earlier onset of stratification of ∼ 16 d and to a delay of stratification termination of ∼ 26 d. The average thermocline depth during stratification became shallower by ∼ 1:345 m, and surface-bottom temperature difference increased over time by 0.249 °C per decade. The creation of a daily time step water temperature dataset not only provided evidence of changes in Erken thermal structure over the last decades, but is also a valuable resource of information that can help in future research on the ecology of Lake Erken. The use of readily available meteorological data to reconstruct Lake Erken's past water temperature is shown to be a useful method to evaluate long-Term changes in lake thermal structure, and it is a method that can be extended to other lakes. © 2019 Author(s)." "57212457154;57191070584;55809001300;7006394349;57212444017;","A module to convert spectral to narrowband snow albedo for use in climate models: SNOWBAL v1.2",2019,"10.5194/gmd-12-5157-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076684298&doi=10.5194%2fgmd-12-5157-2019&partnerID=40&md5=0b62ae81b53979d59f6b863aca3d7d92","Snow albedo schemes in regional climate models often lack a sophisticated radiation penetration scheme and generally compute only a broadband albedo. Here, we present the Spectral-to-NarrOWBand ALbedo module (SNOWBAL, version 1.2) to couple effectively a spectral albedo model with a narrowband radiation scheme. Specifically, the Two-streAm Radiative TransfEr in Snow model (TARTES) is coupled with the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS), cycle 33R1, atmospheric radiation scheme based on the Rapid Radiation Transfer Model, which is embedded in the Regional Atmospheric Climate Model version 2.3p2 (RACMO2). This coupling allows to explicitly account for the effect of clouds, water vapor, snow impurities and snow metamorphism on albedo. Firstly, we present a narrowband albedo method to project the spectral albedos of TARTES onto the 14 spectral bands of the IFS shortwave radiation scheme using a representative wavelength (RW) for each band. Using TARTES and spectral downwelling surface irradiance derived with the DIScrete Ordinate Radiative Transfer atmospheric model, we show that RWs primarily depend on the solar zenith angle (SZA), cloud content and water vapor. Secondly, we compare the TARTES narrowband albedo, using offline RACMO2 results for south Greenland, with the broadband albedo parameterizations of Gardner and Sharp (2010), currently implemented in RACMO2, and the multi-layered parameterization of Kuipers Munneke et al. (2011, PKM). The actual absence of radiation penetration in RACMO2 leads on average to a higher albedo compared with TARTES narrowband albedo. Furthermore, large differences between the TARTES narrowband albedo and PKM and RACMO2 are observed for high SZA and clear-sky conditions, and after melt events when the snowpack is very inhomogeneous. This highlights the importance of accounting for spectral albedo and radiation penetration to simulate the energy budget of the Greenland ice sheet. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License." "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","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 d are observed, associated with increasing aerosol loads (aerosol optical thickness at 550 nm ranging from ĝ1/40.2 to ĝ1/40.7), as well as increasing lofted aerosol layer depth and top altitude. Aerosols are observed up to 6 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 km above mean sea level) seem to come from South America (southern Brazil, Argentina and Uruguay) and reach Henties Bay after 3 to 6 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.
. © Author(s) 2019." "56640979200;7202628826;35768965500;57212443567;7004682973;55675224272;","An increase in methane emissions from tropical Africa between 2010 and 2016 inferred from satellite data",2019,"10.5194/acp-19-14721-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076710263&doi=10.5194%2facp-19-14721-2019&partnerID=40&md5=02f386417d3099eb846ff669b46efd1b","Emissions of methane (CH4) from tropical ecosystems, and how they respond to changes in climate, represent one of the biggest uncertainties associated with the global CH4 budget. Historically, this has been due to the dearth of pan-tropical in situ measurements, which is particularly acute in Africa. By virtue of their superior spatial coverage, satellite observations of atmospheric CH4 columns can help to narrow down some of the uncertainties in the tropical CH4 emission budget. We use proxy column retrievals of atmospheric CH4 (XCH4) from the Japanese Greenhouse gases Observing Satellite (GOSAT) and the nested version of the GEOS-Chem atmospheric chemistry and transport model (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 cm-3) 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.
. © 2019 American Institute of Physics Inc.. All rights reserved." "57205120643;57208124269;57195356653;6507863701;35291021400;","Saccharide Transfer to Sea Spray Aerosol Enhanced by Surface Activity, Calcium, and Protein Interactions",2019,"10.1021/acsearthspacechem.9b00197","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074429257&doi=10.1021%2facsearthspacechem.9b00197&partnerID=40&md5=9b163963a87cce1138c4cf30d7756b09","Sea spray aerosol (SSA) represents the largest source of natural primary aerosol with climate relevance in cloud formation. The aerosol-cloud activation process is influenced by saccharides, which comprise a large SSA organic mass fraction. Saccharides are enriched relative to sodium in SSA by several orders of magnitude but the mechanisms of that enrichment remain poorly understood. Here, saccharide enrichment in laboratory-generated SSA was quantified via bubble bursting experiments using marine-relevant model systems. The resulting particles exhibited core-shell morphology previously observed in SSA, as identified by single particle atomic force microscopy (AFM). Measured enrichment factors (EFs) from filters indicated significant enrichment in aerosol <250 nm in diameter (EF = 1.68 ± 0.19) for the anionic polysaccharide (alginate) and no enrichment (EF = 1) for neutral short-chain saccharides (glucose, sucrose, raffinose, and cyclodextrin). Concurrent surface tension depression was observed for the surface microlayer (SML) with alginate (-Δ12.2 mN m-1 relative to seawater matrix) but not for the short-chain saccharides. Together, results indicate that surface activity of these systems result in saccharide enrichment. Moreover, model system complexity was increased through calcium addition which significantly increased alginate enrichment in aerosol <250 nm in diameter (EF = 2.44 ± 0.26). Separately, protein addition caused the greatest alginate enrichment increase in 500-1000 nm diameter aerosol (EF = 5.77 ± 0.61). These results indicate saccharide surface activity and cooperative interactions with protein and calcium that enhance saccharide enrichment. However, the model systems have not reproduced EFs of natural SSAs and the role of complex ocean biology still needs to be evaluated. Copyright © 2019 American Chemical Society." "8349977900;7004309320;57196233206;6602728668;36143966700;24398562000;55327101700;6603848061;7404544551;7403722047;7102328988;7004936821;24481931900;23485829700;25958801200;57201139948;36110505100;","Perspective on identifying and characterizing the processes controlling iron speciation and residence time at the atmosphere-ocean interface",2019,"10.1016/j.marchem.2019.103704","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074688531&doi=10.1016%2fj.marchem.2019.103704&partnerID=40&md5=d4b2fc0a61ea785180fc5c5bdbfeb8c3","It is well recognized that the atmospheric deposition of iron (Fe) affects ocean productivity, atmospheric CO2 uptake, ecosystem diversity, and overall climate. Despite significant advances in measurement techniques and modeling efforts, discrepancies persist between observations and models that hinder accurate predictions of processes and their global effects. Here, we provide an assessment report on where the current state of knowledge is and where future research emphasis would have the highest impact in furthering the field of Fe atmosphere-ocean biogeochemical cycle. These results were determined through consensus reached by diverse researchers from the oceanographic and atmospheric science communities with backgrounds in laboratory and in situ measurements, modeling, and remote sensing. We discuss i) novel measurement methodologies and instrumentation that allow detection and speciation of different forms and oxidation states of Fe in deliquesced mineral aerosol, cloud/rainwater, and seawater; ii) oceanic models that treat Fe cycling with several external sources and sinks, dissolved, colloidal, particulate, inorganic, and organic ligand-complexed forms of Fe, as well as Fe in detritus and phytoplankton; and iii) atmospheric models that consider natural and anthropogenic sources of Fe, mobilization of Fe in mineral aerosols due to the dissolution of Fe-oxides and Fe-substituted aluminosilicates through proton-promoted, organic ligand-promoted, and photo-reductive mechanisms. In addition, the study identifies existing challenges and disconnects (both fundamental and methodological) such as i) inconsistencies in Fe nomenclature and the definition of bioavailable Fe between oceanic and atmospheric disciplines, and ii) the lack of characterization of the processes controlling Fe speciation and residence time at the atmosphere-ocean interface. Such challenges are undoubtedly caused by extremely low concentrations, short lifetime, and the myriad of physical, (photo)chemical, and biological processes affecting global biogeochemical cycling of Fe. However, we also argue that the historical division (separate treatment of Fe biogeochemistry in oceanic and atmospheric disciplines) and the classical funding structures (that often create obstacles for transdisciplinary collaboration) are also hampering the advancement of knowledge in the field. Finally, the study provides some specific ideas and guidelines for laboratory studies, field measurements, and modeling research required for improved characterization of global biogeochemical cycling of Fe in relationship with other trace elements and essential nutrients. The report is intended to aid scientists in their work related to Fe biogeochemistry as well as program managers at the relevant funding agencies. © 2019 Elsevier B.V." "55173596300;55522941400;57211856505;35069282600;57211857960;","The Impact of Ship Emission Controls Recorded by Cloud Properties",2019,"10.1029/2019GL084700","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075189588&doi=10.1029%2f2019GL084700&partnerID=40&md5=68a0b8bab5c970d941a47afcd9aee2b1","The impact of aerosols on cloud properties is one of the leading uncertainties in the human forcing of the climate. Ships are large, isolated sources of aerosol creating linear cloud formations known as shiptracks. These are an ideal opportunity to identify and measure aerosol-cloud interactions. This work uses over 17,000 shiptracks during the implementation of fuel sulfur content regulations to demonstrate the central role of sulfate aerosol in ship exhaust for modifying clouds. By connecting individual shiptracks to transponder data, it is shown that almost half of shiptracks are likely undetected, masking a significant contribution to the climate impact of shipping. A pathway to retrieving ship sulfate emissions is demonstrated, showing how cloud observations could be used to monitor air pollution. ©2019. American Geophysical Union. All Rights Reserved." "22934904700;7201504886;8696069500;56032970700;7401945370;","A New Perspective for Future Precipitation Change from Intense Extratropical Cyclones",2019,"10.1029/2019GL084001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075207670&doi=10.1029%2f2019GL084001&partnerID=40&md5=bcd29bf221dbd5d1d1d9e50f231924d3","Extratropical cyclones, major contributors to precipitation in the midlatitudes, comprise mesoscale fronts and fine-scale convective storms. Intense oceanic cyclones pose natural hazards, making reliable projections of their changes with global warming of great interest. Here, we analyze the first ever global climate simulations to resolve such mesoscale dynamics of extratropical cyclones. The present-day structure, frequency, and precipitation of the oceanic extratropical cyclones compare well with reanalyses and new satellite datasets that resolve the multiscale cloud-precipitation system. Simulated precipitation from intense oceanic cyclones increases at a rate of 7%/K1, following Clausius-Clapeyron, with warming. The same scaling is apparent also in the interhemispheric contrast, suggesting that the latter could serve as a predictor of the former. Projected changes in precipitation from intense oceanic cyclones with warming may thus be testable using a reliable global observation network of precipitation in the present day. ©2019. The Authors." "57211684836;36720934300;54897465300;57203049177;","Uncertainty in the Evolution of Climate Feedback Traced to the Strength of the Atlantic Meridional Overturning Circulation",2019,"10.1029/2019GL083084","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074814387&doi=10.1029%2f2019GL083084&partnerID=40&md5=cdde8fb667ee93fdaca77ac1eb507675","In most coupled climate models, effective climate sensitivity increases for a few decades following an abrupt CO2 increase. The change in the climate feedback parameter between the first 20 years and the subsequent 130 years is highly model dependent. In this study, we suggest that the intermodel spread of changes in climate feedback can be partially traced to the evolution of the Atlantic Meridional Overturning Circulation. Models with stronger Atlantic Meridional Overturning Circulation recovery tend to project more amplified warming in the Northern Hemisphere a few decades after a quadrupling of CO2. Tropospheric stability then decreases as the Northern Hemisphere gets warmer, which leads to an increase in both the lapse-rate and shortwave cloud feedbacks. Our results suggest that constraining future ocean circulation changes will be necessary for accurate climate sensitivity projections. ©2019. American Geophysical Union. All Rights Reserved." "56910274200;55915046600;57193994250;6603615831;25626678600;7004962346;6603180620;14035386400;8084443000;","Volcanic Plume Aging During Passive Degassing and Low Eruptive Events of Etna and Stromboli Volcanoes",2019,"10.1029/2019JD031122","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074751297&doi=10.1029%2f2019JD031122&partnerID=40&md5=0ecfd3b4260724621fe0acd7fc5c0e0b","Volcanic gases and aerosols emissions from passive degassing or low eruptive events are now included in most climate models despite large uncertainties still exist about their injection height and their temporal and spatial variability. The aim of this study is to quantify the evolution of the gas and aerosols inside volcanic plumes with high kilometric-resolution simulations. With online chemistry and aerosols, these simulations are carried out together with in situ measurements of aerosol and gas-phase properties to assess the impact of Etna and Stromboli volcanic plumes produced by passive degassing and regular Strombolian activity, respectively. Comparison between simulation and observations show that the simulation reproduces the main characteristics of the volcanic plume evolution and confirms that volcanic plumes produced by passive degassing or low eruptive events have a strong impact on cloud condensation nuclei (CCN) formation increasing the number of CCN by a factor of 5. It was also shown that depending on the plume location, the aerosols will act as CCN at different distance from the vent. In the marine atmospheric boundary layer, the aerosols will act as CCN at proximity to the vent (less than 50 km) because of strong condensation sink inhibiting nucleation. In comparison, in the free troposphere, aerosols will act as CCN far from the vent, at more than 200 km. To the best of our knowledge, this study using in situ measurements as well as subkilometric simulations is unique. © 2019. American Geophysical Union. All Rights Reserved." "57211950183;23486734100;56744278700;","Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016",2019,"10.1029/2019JD031017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075467177&doi=10.1029%2f2019JD031017&partnerID=40&md5=ce0c33ca7a43ba0d4b9d3887f0aa3682","The clear sky greenhouse effect (G) is defined as the trapping of infrared radiation by the atmosphere in the absence of clouds. The magnitude and variability of G is an important element in the understanding of Earth's energy balance; yet the quantification of the governing factors of G is poor. The global mean G averaged over 2000 to 2016 is 130–133 W m−2 across data sets. We use satellite observations from Clouds and the Earth's Radiant Energy System Energy Balance and Filled (CERES EBAF) to calculate the monthly anomalies in the clear sky greenhouse effect (ΔG). We quantify the contributions to ΔG due to changes in surface temperature, atmospheric temperature, and water vapor by performing partial radiation perturbation experiments using ERA-Interim and Geophysical Fluid Dynamics Laboratory's Atmospheric Model 4.0 climatological data. Water vapor in the middle troposphere and upper troposphere is found to contribute equally to the global mean and tropical mean ΔG. Holding relative humidity (RH) fixed in the radiative transfer calculations captures the temporal variability of global mean ΔG while variations in RH control the regional ΔG signal. The variations in RH are found to help generate the clear sky super greenhouse effect (SGE). Thirty-six percent of Earth's area exhibits SGE, and this disproportionately contributes to 70% of the globally averaged magnitude of ΔG. In the global mean, G's sensitivity to surface temperature is 3.1–4.0 W m−2 K−1, and the clear sky longwave feedback parameter is 1.5–2.0 W m−2 K−1. Observations from CERES EBAF lie at the more sensitive ends of these ranges and the spread arises from its cloud removal treatment, suggesting that it is difficult to constrain clear sky feedbacks. © 2019. The Authors." "56514334400;7404433688;36497832500;","Regional Variability of Precipitation in Tropical Cyclones Over the Western North Pacific Revealed by the GPM Dual-Frequency Precipitation Radar and Microwave Imager",2019,"10.1029/2019JD031075","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075447262&doi=10.1029%2f2019JD031075&partnerID=40&md5=85efc9c7f01e0e7aa74e291aedb46058","A knowledge of precipitation microphysics of tropical cyclones (TCs) is crucial for forecasts of the TC track and intensity using numerical weather models. Based on five years of measurements of TCs over the western North Pacific from the dual-frequency precipitation radar and the microwave imager on board the Global Precipitation Measurement satellite, the precipitation characteristics and microphysical processes in different regions of TCs and their associations with ice scattering signals are investigated. In the region close to the TC center, the storm top height (STH) and near-surface rain rate are high, and the hydrometeors have a high concentration and a relatively low mass-weighted mean diameter (Dm). In the outer TC region, the distributions of the reflectivity factor (Ze) and Dm become broader as the mean Dm increases. Ze and Dm values generally increase below the melting layer, indicating the predominant role of collision–coalescence processes. The occurrence probability of collision–coalescence is greater than 90% when STH is less than 5 km and the polarization-corrected temperature at 89 GHz is greater than 250 K. When the STH exceeds 5 km, the collision–coalescence process is also predominant in the eyewall region; however, the influence of the breakup process increases in the rainband regions. © 2019. American Geophysical Union. All Rights Reserved." "56681868600;56510058800;57211681734;56539575600;8573340700;","Microphysics of Snowfall Over Coastal East Antarctica Simulated by Polar WRF and Observed by Radar",2019,"10.1029/2019JD031028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074855564&doi=10.1029%2f2019JD031028&partnerID=40&md5=6f8ac77f1b5971f8bc7b6e83896354ed","The current assessment of the Antarctic surface mass balance mostly relies on reanalysis products or climate model simulations. However, little is known about the ability of models to reliably represent the microphysical processes governing the precipitation. This study makes use of recent ground-based precipitation measurements at Dumont d'Urville station in Adélie Land to evaluate the representation of the precipitation microphysics in the Polar version of the Weather Research Forecast (Polar WRF) atmospheric model. During two summertime snowfall events, high-resolution simulations are compared to measurements from an X-band polarimetric radar and from a Multi-Angle Snowflake Camera (MASC). A radar simulator and a “MASC” simulator in Polar WRF make it possible to compare similar observed and simulated variables. Radiosoundings and surface-meteorological observations were used to assess the representation of the regional dynamics in the model. Five different microphysical parameterizations are tested. The simulated temperature, wind, and humidity fields are in good agreement with the observations. However, the amount of simulated surface precipitation shows large discrepancies with respect to observations, and it strongly differs between the simulations themselves, evidencing the critical role of the microphysics. The inspection of vertical profiles of reflectivity and mixing ratios revealed that the representation of the sublimation process by the low-level dry katabatic winds strongly influences the actual amount of precipitation at the ground surface. By comparing the simulated radar signal as well as MASC and model particle size distributions, it is also possible to identify the microphysical processes involved and to pinpoint shortcomings within the tested parameterizations. © 2019. American Geophysical Union. All Rights Reserved." "57211783565;36697726500;7004047492;8538703200;8262131200;24280225800;","Intercomparison of Snow Melt Onset Date Estimates From Optical and Microwave Satellite Instruments Over the Northern Hemisphere for the Period 1982–2015",2019,"10.1029/2018JD030197","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074971492&doi=10.1029%2f2018JD030197&partnerID=40&md5=09ec6ef65049e011a6715e49e56b54a7","Robust melt season timing and length estimates are important for hydrological and climatological applications; due to the large area and sparse in situ measurements, snow melt monitoring at the continental scale is only possible from satellites. We intercompared melt onset date (MOD) estimates obtained from optical and microwave satellite sensors over the Northern Hemisphere between 1982 and 2015 and subsequently analyzed the causes of the similarities and dissimilarities found. The optical satellite data are based on the mean surface albedo from the Satellite Application Facility for Climate Monitoring (CM SAF) CLouds, Albedo and RAdiation second release Surface ALbedo (CLARA-A2 SAL) data set. The microwave satellite data are based on temporal variations in the differences of the brightness temperature from satellite passive microwave radiometers. The analysis shows that the microwave-based method detects melt onset on average 10 days later than the albedo-based method, which results from the different melt detection methods; the albedo-based method observes the point when the spring snow metamorphism begins to have a detectable effect on snow albedo, whereas the microwave-based method detects the appearance of meltwater in snowpack. The difference in MOD decreases in forests, because canopy protects snow from sunlight delaying snow metamorphism. Additionally, we analyzed the MOD estimates for trends across the Northern Hemisphere and separately for Eurasia and North America. A statistically significant negative trend toward earlier melt onset exists in all cases, which is consistent with previous studies. © 2019. The Authors." "57208328348;25823150000;57210896620;35610780800;7402424104;6602106761;55488450500;7103230940;","Paleoclimate of the subtropical Andes during the latest Miocene, Lauca Basin, Chile",2019,"10.1016/j.palaeo.2019.109336","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071773420&doi=10.1016%2fj.palaeo.2019.109336&partnerID=40&md5=2980499497d6c3caa40ae7c687979ee3","Uplift of the Andean Cordillera during the Miocene and Pliocene produced large-scale changes in regional atmospheric circulation that impacted local ecosystems. The Lauca Basin (northern Chilean Altiplano) contains variably fluvial and lacustrine sedimentary sequences spanning the interval from 8.7 to 2.3 Ma. Field samples were collected from paleo-lacustrine sediments in the basin. Sediments were dated using detrital zircon geochronology on volcanic tuffs, yielding an age range between ~5.57 and 5.44 Ma. These new age constraints provided an opportunity to evaluate changes in the Lauca Basin ecosystem across this dynamic Miocene-Pliocene transition. We employed multiple proxies (lithofacies analysis, diatoms, pollen, and oxygen stable isotopes of authigenic carbonates) to interpret ancient lacustrine and terrestrial paleoenvironments. Alternations among mudstone, carbonate, and evaporitic facies indicate lake-level variability through time. The diatom assemblage is characterized by meso- to hypersaline and alkaline-tolerant taxa typical of shallow lakes. The δ18O values ranged from −8.96 to −2.22‰ indicating fluctuations in water balance. Pollen taxa in the outcrop are typical of a transitional stage between seasonal cloud forest and open grassland. Together, these proxies indicate that the Lauca paleolake sediments were deposited under a wetter-than-modern climate with high temporal variability. Our results refine previous studies in the Lauca Basin and are consistent with other regional studies suggesting that the South American summer monsoon at the Miocene-Pliocene transition was more intense than it is at present. © 2019" "57192948327;57206511020;15319530000;","Diurnal cycle of rainfall and convection over the Maritime Continent using TRMM and ISCCP",2019,"10.1002/joc.6121","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066055607&doi=10.1002%2fjoc.6121&partnerID=40&md5=aae1c279375b48019166d19fb0f9e301","This study investigates the diurnal cycle of rainfall, convection, and precipitation features (PFs) over the Maritime Continent (MC). The study uses Tropical Rainfall Measuring Missions (TRMM) Multi-satellite Precipitation Analysis (TMPA; product 3b42), TRMM PFs, and convective classifications from the International Satellite Cloud Climatology Project (ISCCP) data. Together, these satellites dataset paint a comprehensive picture of the diurnal cycle of rainfall and convection over the MC consistent with past research. Isolated convection initiates around midday over the higher terrain of the large islands (Java, Borneo, and Papua New Guinea). The convection becomes more organized through the afternoon and evening, leading to peak rainfall over the islands around 1800–2100 local standard time (LST). Over the next few hours, some of that rainfall transitions to stratiform rain over land. The convection then propagates offshore overnight with rainfall peaking along the coast around 0300–0600 LST and then over ocean around 0600–0900 LST. ISCCP data suggests that the overnight and early morning convection is more associated with isolated convective cells than the remnants of mesoscale convective systems. The coastal and oceanic diurnal ranges also seem to be larger in stratiform rainfall, in contrast to land where convective rainfall dominates. Seasonally the diurnal variation of rainfall, convection, and PFs over the region have greater amplitude during DJF (December, January, and February) than JJA (June, July, and August). Given the MC's critical role in the global climate, examining variations in these cycles with respect to the Madden–Julian Oscillation and equatorial waves may ultimately lead to improved subseasonal weather forecasts. © 2019 Royal Meteorological Society" "16443990500;57211776806;57211782402;56017066000;57211789465;55557545200;","Technical note: Frenkel, Halsey and Hill analysis of water on clay minerals: Toward closure between cloud condensation nuclei activity and water adsorption",2019,"10.5194/acp-19-13581-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075003552&doi=10.5194%2facp-19-13581-2019&partnerID=40&md5=18c4beeb7576ccc6dbf0e6dfe58af1b2","Insoluble atmospheric aerosol, such as mineral dust, has been identified as an important contributor to the cloud droplet number concentration and indirect climate effect. However, empirically derived Frenkel-Halsey-Hill (FHH) water adsorption parameters remain the largest source of uncertainty in assessing the effect of insoluble aerosol on climate using the FHH activation theory (FHH-AT). Furthermore, previously reported FHH water adsorption parameters for illite and montmorillonite determined from water adsorption measurements below 100 % RH do not satisfactorily agree with values determined from FHH-AT analysis of experimental cloud condensation nuclei (CCN) measurements under supersaturated conditions. The work reported here uses previously reported experimental water adsorption measurements for illite and montmorillonite clays (Hatch et al., 2012, 2014) to show that improved analysis methods that account for the surface microstructure are necessary to obtain better agreement of FHH parameters between water adsorption and experimental CCN-derived FHH parameters. © Author(s) 2019." "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." "57211646937;43061335300;8380252900;55326237100;36486362800;","Analysis and quantification of ENSO-linked changes in the tropical Atlantic cloud vertical distribution using 14 years of MODIS observations",2019,"10.5194/acp-19-13535-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074713353&doi=10.5194%2facp-19-13535-2019&partnerID=40&md5=31085160e89724dc1d3d48d6a45cb4a9","A total of 14 years (September 2002 to September 2016) of Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) monthly mean cloud data are used to quantify possible changes in the cloud vertical distribution over the tropical Atlantic. For the analysis multiple linear regression techniques are used. For the investigated time period significant linear changes were found in the domain-averaged cloud-top height (CTH) (-178m per decade), the high-cloud fraction (HCF) (-0.0006 per decade), and the low-cloud amount (0.001 per decade). The interannual variability of the time series (especially CTH and HCF) is highly influenced by the El Niño-Southern Oscillation (ENSO). Separating the time series into two phases, we quantified the linear change associated with the transition from more La Niña-like conditions to a phase with El Niño conditions (Phase 2) and vice versa (Phase 1). The transition from negative to positive ENSO conditions was related to a decrease in total cloud fraction (TCF) (-0.018 per decade; not significant) due to a reduction in the high-cloud amount (-0.024 per decade; significant). Observed anomalies in the mean CTH were found to be mainly caused by changes in HCF rather than by anomalies in the height of cloud tops themselves. Using the large-scale vertical motion ω at 500 hPa (from ERA-Interim ECMWF reanalysis data), the observed anomalies were linked to ENSO-induced changes in the atmospheric large-scale dynamics. The most significant and largest changes were found in regions with strong large-scale upward movements near the Equator. Despite the fact that with passive imagers such as MODIS it is not possible to vertically resolve clouds, this study shows the great potential for large-scale analysis of possible changes in the cloud vertical distribution due to the changing climate by using vertically resolved cloud cover and linking those changes to large-scale dynamics using other observations or model data. © Author(s) 2019." "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." "57201681614;36152171200;35329672300;6602182223;38362385200;56959736200;","Investigating the assimilation of CALIPSO global aerosol vertical observations using a four-dimensional ensemble Kalman filter",2019,"10.5194/acp-19-13445-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074578658&doi=10.5194%2facp-19-13445-2019&partnerID=40&md5=3862d8d586ebd479b33468aa21dc5bc6","Aerosol vertical information is critical to quantify the influences of aerosol on the climate and environment; however, large uncertainties still persist in model simulations. In this study, the vertical aerosol extinction coefficients from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are assimilated to optimize the hourly aerosol fields of the Non-hydrostatic ICosahedral Atmospheric Model (NICAM) online coupled with the Spectral Radiation Transport Model for Aerosol Species (SPRINTARS) using a four-dimensional local ensemble transform Kalman filter (4-D LETKF). A parallel assimilation experiment using bias-corrected aerosol optical thicknesses (AOTs) from the Moderate Resolution Imaging Spectroradiometer (MODIS) is conducted to investigate the effects of assimilating the observations (and whether to include vertical information) on the model performances. Additionally, an experiment simultaneously assimilating both CALIOP and MODIS observations is conducted. The assimilation experiments are successfully performed for 1 month, making it possible to evaluate the results in a statistical sense. The hourly analyses are validated via both the CALIOP-observed aerosol vertical extinction coefficients and the AOT observations from MODIS and the AErosol RObotic NETwork (AERONET). Our results reveal that both the CALIOP and MODIS assimilations can improve the model simulations. The CALIOP assimilation is superior to the MODIS assimilation in modifying the incorrect aerosol vertical distributions and reproducing the real magnitudes and variations, and the joint CALIOP and MODIS assimilation can further improve the simulated aerosol vertical distribution. However, the MODIS assimilation can better reproduce the AOT distributions than the CALIOP assimilation, and the inclusion of the CALIOP observations has an insignificant impact on the AOT analysis. This is probably due to the nadir-viewing CALIOP having much sparser coverage than MODIS. The assimilation efficiencies of CALIOP decrease with increasing distances of the overpass time, indicating that more aerosol vertical observation platforms are required to fill the sensor-specific observation gaps and hence improve the aerosol vertical data assimilation. © 2019 BMJ Publishing Group. All rights reserved." "57211754995;36720934300;26645289600;55332348600;","Distinct patterns of cloud changes associated with decadal variability and their contribution to observed cloud cover trends",2019,"10.1175/JCLI-D-18-0443.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074899804&doi=10.1175%2fJCLI-D-18-0443.1&partnerID=40&md5=6824fcb81f52db428851e55910945951","With the goal of understanding the relative roles of anthropogenic and natural factors in driving observed cloud trends, this study investigates cloud changes associated with decadal variability including the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO). In the preindustrial simulations of CMIP5 global climate models (GCMs), the spatial patterns and the vertical structures of the PDO-related cloud cover changes in the Pacific are consistent among models. Meanwhile, the models show consistent AMO impacts on high cloud cover in the tropical Atlantic, subtropical eastern Pacific, and equatorial central Pacific, and on low cloud cover in the North Atlantic and subtropical northeast Pacific. The cloud cover changes associated with the PDO and the AMO can be understood via the relationships between large-scale meteorological parameters and clouds on interannual time scales. When compared to the satellite records during the period of 1983-2009, the patterns of total and low cloud cover trends associated with decadal variability are significantly correlated with patterns of cloud cover trends in ISCCP observations. On the other hand, the pattern of the estimated greenhouse gas (GHG)-forced trends of total cloud cover differs from that related to decadal variability, and may explain the positive trends in the subtropical southeast Pacific, negative trends in the midlatitudes, and positive trends poleward of 508N/S. In most models, the magnitude of the estimated decadal variability contribution to the observed cloud cover trends is larger than that contributed by GHG, suggesting the observed cloud cover trends are more closely related to decadal variability than to GHG-induced warming. © 2019 American Meteorological Society." "6507019560;8719703500;55747131500;7006783796;6506827279;24759591600;57211010680;7403625607;12803465300;26427916400;24322892500;","Global Cloud Detection for CERES Edition 4 Using Terra and Aqua MODIS Data",2019,"10.1109/TGRS.2019.2926620","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064639458&doi=10.1109%2fTGRS.2019.2926620&partnerID=40&md5=15305611842645ffb25a3797379853af","The Clouds and Earth's Radiant Energy System (CERES) has been monitoring clouds and radiation since 2000 using algorithms developed before 2002 for CERES Edition 2 (Ed2) products. To improve cloud amount accuracy, CERES Edition 4 (Ed4) applies revised algorithms and input data to Terra and Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) radiances. The Ed4 cloud mask uses 5-7 additional channels, new models for clear-sky ocean and snow/ice-surface radiances, and revised Terra MODIS calibrations. Mean Ed4 daytime and nighttime cloud amounts exceed their Ed2 counterparts by 0.035 and 0.068. Excellent consistency between average Aqua and Terra cloud fraction is found over nonpolar regions. Differences over polar regions are likely due to unresolved calibration discrepancies. Relative to Ed2, Ed4 cloud amounts agree better with those from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). CALIPSO comparisons indicate that Ed4 cloud amounts are more than or as accurate as other available cloud mask systems. The Ed4 mask correctly identifies cloudy or clear areas 90%-96% of the time during daytime over nonpolar areas depending on the CALIPSO-MODIS averaging criteria. At night, the range is 88%-95%. Accuracy decreases over land. The polar day and night accuracy ranges are 90%-91% and 80%-81%, respectively. The mean Ed4 cloud fractions slightly exceed the average for seven other imager cloud masks. Remaining biases and uncertainties are mainly attributed to errors in Ed4 predicted clear-sky radiances. The resulting cloud fractions should help CERES produce a more accurate radiation budget and serve as part of a cloud property climate data record. © 2019 IEEE." "35332074200;6506539438;","On the Causal Relationship Between the Moist Diabatic Circulation and Cloud Rapid Adjustment to Increasing CO2",2019,"10.1029/2019MS001853","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075723592&doi=10.1029%2f2019MS001853&partnerID=40&md5=d463683b00bf71c2e2608a28282d6379","General circulation models predict that clouds in the atmosphere rapidly adjust to the radiative perturbation of an abrupt increase in atmospheric CO2 concentration on a short time scale of about 10 days. This rapid adjustment consists of an increase of clouds in the boundary layer and a decrease of clouds in the free troposphere. Our focus is the mechanism for the decrease of clouds in the free troposphere, which is the dominating component of cloud rapid adjustment in most general circulation models. We propose that the decrease in clouds in the free troposphere arises from the causal relationship between the moist diabatic circulation and the production of condensates that forms clouds in moist processes. As CO2 concentration increases, tropospheric radiative cooling is reduced, resulting in weakening of the moist diabatic circulation and a decrease in precipitation. As the hydrologic cycle weakens and the moist processes involving phase change of water vapor to form the condensates in the atmosphere lessen, the mass of cloud condensates decreases. This decrease in cloud condensates can be predicted from the decrease in the radiative subsidence mass flux, which is a metric for the strength of the moist diabatic circulation in the free troposphere. ©2019. The Authors." "57196699811;8882641700;7003447904;23493268700;","Nonequilibrium Fractionation During Ice Cloud Formation in iCAM5: Evaluating the Common Parameterization of Supersaturation as a Linear Function of Temperature",2019,"10.1029/2019MS001764","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075481969&doi=10.1029%2f2019MS001764&partnerID=40&md5=6449c2ca63334c9ba51216c5f98b09d1","Supersaturation with respect to ice determines the strength of nonequilibrium fractionation during vapor deposition onto ice or snow and therefore influences the water isotopic composition of vapor and precipitation in cold environments. Historically, most general circulation models formed clouds through saturation adjustment and therefore prevented supersaturation. To match the observed isotopic content, especially the deuterium excess, of snow in polar regions, the saturation ratio with respect to ice (Si) was parameterized, usually by assuming a linear dependence of Si on temperature. The Community Atmosphere Model Version 5 (CAM5) no longer applies saturation adjustment for the ice phase and thus allows ice supersaturation. Here, we adapt the isotope-enabled version of CAM5 to compute nonequilibrium fractionation in ice and mixed-phase clouds based on Si from the CAM5 microphysics and use it to evaluate the common parameterization of Si. Our results show a wide range of Si predicted by the CAM5 microphysics and reflected in the simulated deuterium excess of Antarctic precipitation; this is overly simplified by the linear parameterization. Nevertheless, a linear function, when properly tuned, can reproduce the average observed relationship between δD and deuterium excess reasonably well. However, only the model-predicted Si can capture changes in microphysical conditions under different climate states that are not due to changes in temperature. Furthermore, parametric sensitivity tests show that with the model-predicted Si, water isotopes are more closely tied to the model microphysics and can therefore constrain uncertain microphysical parameters. ©2019. The Authors." "37107744600;7202208382;6701835010;","Multiple-Instance Superparameterization: 2. The Effects of Stochastic Convection on the Simulated Climate",2019,"10.1029/2019MS001611","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075418974&doi=10.1029%2f2019MS001611&partnerID=40&md5=f633b9276c248872b6c747de09e01b5f","The cloud-permitting model (CPM) of the superparameterized Community Atmosphere Model (SP-CAM) is a stochastic parameterization. As reported in a companion paper, we have created a variant of SP-CAM, called MP-CAM, that uses the averaged feedback of 10 independent two-dimensional CPMs in each global model column, in place of the single CPM of SP-CAM. This ensemble-averaged feedback is interpreted as an approximation to the feedback from a deterministic parameterization. We present evidence that the multiple-instance superparameterization of MP-CAM is indeed more deterministic than SP-CAM. The climates of the SP and MP configurations are compared, giving particular attention to extreme precipitation events and convectively coupled large-scale tropical weather systems, such as the Madden-Julian Oscillation. A number of small but significant changes in the mean state climate are uncovered, and the deterministic parameterization slightly degrades the Madden-Julian Oscillation simulation. ©2019. The Authors." "23485410200;56059501400;24329376600;7004539332;12787547600;57211688971;55715917500;7401751388;57191589111;7004966070;7006766881;7003976079;6603887794;7004764167;57210240098;","The Impact of Prescribed Ozone in Climate Projections Run With HadGEM3-GC3.1",2019,"10.1029/2019MS001714","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074870834&doi=10.1029%2f2019MS001714&partnerID=40&md5=af60f357902bdd7c09d9175f4f15f3c1","The Coupled Model Intercomparison Project 6 protocol suggests prescribing preindustrial ozone concentrations in abrupt-4xCO2 simulations. This leads to a mismatch between the thermal tropopause, which rises due to climate change, and the ozone tropopause, which remains fixed. The result is unphysically high ozone concentrations in the upper troposphere, leading to a warm bias in cold point temperature and increased stratospheric water vapor. In the U.K. physical climate model HadGEM3-GC3.1 this increases the surface climate sensitivity. In the future, other climate models without interactive ozone schemes may face similar problems. We describe a method to interactively redistribute ozone in climate simulations, which removes the inconsistency between the thermal and ozone tropopause heights while retaining the prescribed ozone distribution as closely as possible. This removes unphysical consequences of the tropopause mismatch, while still allowing a fair comparison against other Coupled Model Intercomparison Project 6 model simulations. After each model year, the monthly mean, zonal mean, thermal tropopause is formed based on the previous two model years. The ozone tropopause is defined at 1 km below the thermal tropopause by setting ozone concentrations there to 80 ppbv, and smoothing appropriately. The mass of ozone removed from the troposphere is added to the stratosphere thus conserving the total mass of ozone. This redistribution is then applied proportionally to the 3-D monthly mean ozone concentrations. The climate model is run for the following year, using this redistributed ozone, and then the whole process is repeated. Results are presented from preindustrial and abrupt-4xCO2 simulations, but this method can be used for any climate simulation. ©2019. Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland." "56377286600;55923546200;8942524900;56571063800;35810775100;36171703500;7103373205;36637844900;6602182223;57208121852;49861577800;10139397300;55480654300;8633783900;7405666962;7404747615;56487420600;43661479500;7004469744;","Ensembles of Global Climate Model Variants Designed for the Quantification and Constraint of Uncertainty in Aerosols and Their Radiative Forcing",2019,"10.1029/2019MS001628","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068573791&doi=10.1029%2f2019MS001628&partnerID=40&md5=0b39f8ea49613abeb310a2eacc624d88","Tropospheric aerosol radiative forcing has persisted for many years as one of the major causes of uncertainty in global climate model simulations. To sample the range of plausible aerosol and atmospheric states and perform robust statistical analyses of the radiative forcing, it is important to account for the combined effects of many sources of model uncertainty, which is rarely done due to the high computational cost. This paper describes the designs of two ensembles of the Met Office Hadley Centre Global Environment Model-U.K. Chemistry and Aerosol global climate model and provides the first analyses of the uncertainties in aerosol radiative forcing and their causes. The first ensemble was designed to comprehensively sample uncertainty in the aerosol state, while the other samples additional uncertainties in the physical model related to clouds, humidity, and radiation, thereby allowing an analysis of uncertainty in the aerosol effective radiative forcing. Each ensemble consists of around 200 simulations of the preindustrial and present-day atmospheres. The uncertainty in aerosol radiative forcing in our ensembles is comparable to the range of estimates from multimodel intercomparison projects. The mean aerosol effective radiative forcing is −1.45 W/m2 (credible interval of −2.07 to −0.81 W/m2), which encompasses but is more negative than the −1.17 W/m2 in the 2013 Atmospheric Chemistry and Climate Model Intercomparison Project and −0.90 W/m2 in the Intergovernmental Panel on Climate Change Fifth Assessment Report. The ensembles can be used to reduce aerosol radiative forcing uncertainty by challenging them with multiple measurements as well as to isolate potential causes of multimodel differences. ©2019. The Authors." "55979522800;26435318900;8634442200;","Assessing plant production responses to climate across water-limited regions using Google Earth Engine",2019,"10.1016/j.rse.2019.111379","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073226048&doi=10.1016%2fj.rse.2019.111379&partnerID=40&md5=e80abcc30c06d8b7519bc72ff1ef8d69","Climate variability and change acting at broad scales can lead to divergent changes in plant production at local scales. Quantifying how production responds to variation in climate at local scales is essential to understand underlying ecological processes and inform land management decision-making, but has historically been limited in spatiotemporal scale based on the use of discrete ground-based measurements or coarse resolution satellite observations. With the advent of cloud-based computing through Google Earth Engine (GEE), production responses to climate can be evaluated across broad landscapes though time at a resolution useful for ecological and land management applications. Here, GEE was employed to synthesize a multi-platform Landsat time series (1988–2014) and evaluate relationships between the soil-adjusted vegetation index (a proxy for plant production) and climate across deserts and plant communities of the southwestern U.S. A “climate pivot point” approach was adopted in GEE to assess the trade-off between production responses to increasing wetness and resistances to drought at 30-m resolution. Consistent with a long-term seasonal climate gradient, production was most related to climate variance during the cool-season in the western deserts, during the warm-season in the eastern deserts, and equally related to both seasons within several desert areas. Communities dominated by grasses and deciduous trees displayed large production responses to an increase in wetness and low resistances to water deficit, while shrublands and evergreen woodlands had variable responses and high drought resistances. Production in plant communities that spanned multiple deserts responded differently to seasonal climate variability in each desert. Defining these plant production sensitivities to climate at 30-m resolution in GEE advances forecasts of how long-term climate trajectories may affect carbon storage, wildlife habitat, and the vulnerability of water-limited ecosystems. © 2019 Elsevier Inc." "55751665200;7404178566;56996574200;57210313106;57190375944;23092272700;57209413112;54785279700;","Impact of convective parameterization on the seasonal prediction skill of Indian summer monsoon",2019,"10.1007/s00382-019-04921-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070312204&doi=10.1007%2fs00382-019-04921-y&partnerID=40&md5=b8c7b6bad288f185c54138fe5d759f9b","The sensitivity of seasonal predictions of the Indian summer monsoon (ISM) to convection parameterization schemes (CPS) is studied using 37 years of hindcast experiments. The predictions are quite sensitive to changes in these schemes and improve the skill by 18–28%. Though the mean state circulation and rainfall over India improves, the sea surface temperature (SST) biases increase in the sensitivity experiments compared to the control run. The ability of the model to realistically capture the teleconnections associated with monsoon such as the El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) also appears to change with different CPS. It is found that the suitability of a CPS for ISM in the Climate Forecast System version 2 (CFSv2) stems from its ability to capture cloud fractions realistically and keep the SST biases to a minimum. The revised Simplified-Arakawa–Schubert (SAS2, Han and Pan in Weather Forecast 26:520–533. https://doi.org/10.1175/waf-d-10-05038.1, 2011) scheme gives better prediction skill for ISM compared to the skill score obtained from SAS2 with shallow convection (SAS2sc) primarily because it simulates realistic clouds, without aggravating the SST biases, particularly in the tropical Pacific Ocean, and captures the Indian Ocean teleconnections realistically. SAS2sc significantly under-estimates the low-level clouds over global equatorial region, despite simulating better mid and high-level clouds, higher Nino 3.4 skill, and better inter-annual variability of ISM. The cold SST bias in the tropical basins is large in SAS2sc. Therefore, to exploit the merits of SAS2sc, unrealistic suppression of low clouds needs to be addressed, and the cold SST biases need to be minimized. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "57087451200;7103180783;53880473700;53879901600;12787547600;6602080205;","Attribution of recent trends in temperature extremes over China: Role of changes in anthropogenic aerosol emissions over asia",2019,"10.1175/JCLI-D-18-0777.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074927588&doi=10.1175%2fJCLI-D-18-0777.1&partnerID=40&md5=07d873a68f0f46904fcaebbde3ad5564","Observations indicate large changes in temperature extremes over China during the last four decades, exhibiting as significant increases in the amplitude and frequency of hot extremes and decreases in the amplitude and frequency of cold extremes.An ensemble of transient experimentswith the fully coupled atmosphere-ocean model HadGEM3-GC2, including both anthropogenic forcing and natural forcing, successfully reproduces the spatial pattern andmagnitude of observed historical trends in both hot and cold extremes. Themodel-simulated trends in temperature extremes primarily come fromthe positive trends in clear-sky longwave radiation,which is mainly due to the increases in greenhouse gases (GHGs). An ensemble of sensitivity experiments with Asian anthropogenic aerosol (AA) emissions fixed at their 1970s levels tends to overestimate the trends in temperature extremes, indicating that local AA emission changes have moderated the trends in these temperature extremes over China. The recent increases in Asian AA drive cooling trends over China by inducing negative clear-sky shortwave radiation directly through the aerosol-radiation interaction, which partly offsets the strong warming effect by GHG changes. The cooling trends induced by Asian AA changes are weaker over northern China during summer, which is due to the warming effect by the positive shortwave cloud radiative effect through the AA-induced atmosphere-cloud feedback. This accounts for the observed north-south gradients of the historical trends in some temperature extremes over China, highlighting the importance of local Asian AA emission changes on spatial heterogeneity of trends in temperature extremes. © 2019 American Meteorological Society." "7405972102;46461963400;","Effect of human-induced land disturbance on subseasonal predictability of near-surface variables using an atmospheric general circulation model",2019,"10.3390/atmos10110725","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075739179&doi=10.3390%2fatmos10110725&partnerID=40&md5=4ce849ae2fde29b83212ca8cc3023e08","Irrigation can affect climate and weather patterns from regional to global scales through the alteration of surface water and energy balances. Here, we couple a land-surface model (LSM) that includes various human land-water management activities including irrigation with an atmospheric general circulation model (AGCM) to examine the impacts of irrigation-induced land disturbance on the subseasonal predictability of near-surface variables. Results indicate that the simulated global irrigation and groundwater withdrawals (circa 2000) are ~3600 and ~370 km3/year, respectively, which are in good agreement with previous estimates from country statistics and offline-LSMs. Subseasonal predictions for boreal summers during the 1986-1995 period suggest that the spread among ensemble simulations of air temperature can be substantially reduced by using realistic land initializations considering irrigation-induced changes in soil moisture. Additionally, it is found that the subseasonal forecast skill for near-surface temperature and sea level pressure significantly improves when human-induced land disturbance is accounted for in the AGCM. These results underscore the need to incorporate irrigation into weather forecast models, such as the global forecast system. © 2019 by the authors." "54782254200;14041940100;57204816643;57211264937;6603089483;7005335914;","Mapping three decades of annual irrigation across the US High Plains Aquifer using Landsat and Google Earth Engine",2019,"10.1016/j.rse.2019.111400","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073250116&doi=10.1016%2fj.rse.2019.111400&partnerID=40&md5=c5434fe8cc2ef77c8d50bc697287407c","Understanding how irrigated areas change over time is vital to effectively manage limited agricultural water resources, but long-term, high-resolution, and spatially explicit datasets are rare. The High Plains Aquifer (HPA) in the central United States is one of the largest and most stressed aquifer systems in the world. It supports a $20 billion economy, but groundwater use is unsustainable over much of the aquifer. Emerging cloud computing tools like Google Earth Engine (GEE) make it possible to use the full Landsat record to monitor regional systems like the HPA with high spatial and temporal resolution over multiple decades. However, challenges remain to develop irrigation classification methods that are robust to a wide range of climate conditions and crop types, evolving management, and missing data. Here, we addressed these challenges to produce an annual, moderately high resolution (30 m) irrigation map time series from 1984 to 2017 over the aquifer. Leveraging GEE's extensive data catalog, we combined Landsat imagery, environmental covariables, and a large heterogeneous ground truth dataset to create a single random forest classifier applied annually to the entire region. Following classification, we applied the Bayesian Updating of Land-Cover (BULC) algorithm to fill imagery gaps and reduce commission errors in the provisional irrigation time series. Novel neighborhood greenness indices contributed to an overall 91.4% map accuracy across years; county statistics (r2 = 0.86) were similarly well-matched. Trend analysis of irrigated area through time identified regions of stable, expanding, and declining irrigated area. Given declining aquifer storage, we estimate that up to 24% of currently irrigated area may be lost this century. To date, the map dataset is the longest, highest resolution large-scale record of where and when irrigation occurs. It is freely available for stakeholders, managers, and researchers to inform policies and management decisions, as well as for use in hydrology, agronomy, and climate models. © 2019 Elsevier Inc." "56421015100;40661134200;55512618700;56892981800;57195760228;56003715500;57190809882;56539489100;7403248284;36912780500;55754690200;7408519295;","Land–atmosphere interaction over the Indo-China Peninsula during spring and its effect on the following summer climate over the Yangtze River basin",2019,"10.1007/s00382-019-04922-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072045874&doi=10.1007%2fs00382-019-04922-x&partnerID=40&md5=f191c2576e9c051fb73d9e7298e07139","Land–atmosphere interaction plays an important role in regional weather and climate. Using the soil moisture (SM) data from the Global Land Data Assimilation System V2.0, the present study examines the land–atmosphere interaction during spring over the Indo-China Peninsula (ICP) and its effect on the following summer climate over the Yangtze River basin. The analyses show that the abnormal SM over the ICP in spring would significantly change the local surface air temperature by affecting the evapotranspiration. In particular, such a SM effect on the local air temperature can persist to the following summer owing to a strong ICP SM memory, which can in turn influence the East Asian summer monsoon as well as the remote precipitation and temperature over the Yangtze River basin. The persistent abnormally lower (higher) SM over the ICP induces less (more) local evapotranspiration, increasing (decreasing) the surface temperature. The resultant anomalous heating (cooling) over the ICP raises (lowers) the local geopotential height, which attracts (repels) the Western Pacific Subtropical High (WPSH) extending westward. Accompanied by an excessive westward extension of the summer WPSH, an anomalously enhanced southwesterly wind would bring more moisture to the Yangtze River basin at the lower troposphere. This situation intensifies the Meiyu front and precipitation over the Yangtze River basin. Further thermodynamic and dynamic analyses support that the monsoonal circulation anomalies associated with the westward extension of the WPSH mainly contribute to the summer precipitation anomalies over the Yangtze River basin. In addition, more precipitation accompanied with more cloud cover and less downward solar radiation that reduce the local air temperature, and vice versa. This highlights that the spring SM over the ICP is an important predictor for the following summer climate over the East Asia. The implication for predicting extreme weather events in summer over the Yangtze River basin is also discussed. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "57204839371;57205189680;35084022000;","Four centuries of vegetation change in the mid-elevation Andean forests of Ecuador",2019,"10.1007/s00334-019-00715-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073873579&doi=10.1007%2fs00334-019-00715-8&partnerID=40&md5=a4a95596d3d1a14c4ba2e1e839dd3bfe","Mid-elevation Andean ecosystems have immense species richness and endemism. Taxonomic composition is known to change through time on the eastern slopes of the Andes as a result of climatic change and disturbance events, both natural and by human actions. Fossil phytoliths can capture local scale vegetation changes, especially among monocotyledonous plants. Phytolith production is high in grasses and palms, plant groups that are particularly sensitive to climatic changes and disturbance events in Andean ecosystems. Here, we reconstruct four centuries of local-scale vegetation change and the corresponding fire history from lake sediment records retrieved from Lagunas Cormorán and Chimerella, located at ca. 1,700 m a.s.l. in the mid-elevation Andean forests of eastern Ecuador. The charcoal analysis of the lake sediments showed no sign of past fires, and no evidence of cultivation was found at either lake. The phytolith assemblages indicated changes in the relative abundances of palms, grasses and trees over the last few centuries, suggesting that mid-elevation Andean phytolith assemblages are sensitive to local scale vegetation dynamics. The largest change in vegetation occurred at the end of the Little Ice Age, at which point the diversity of palm phytoliths decreases. These phytolith assemblages are probably responding to changes in the cloud base position through time, which strongly influences the distributions of many plants and animals. © 2019, The Author(s)." "57213629818;7005035762;7006256622;","Fast SST error growth in the southeast Pacific Ocean: comparison between high and low-resolution CCSM4 retrospective forecasts",2019,"10.1007/s00382-019-04855-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067700459&doi=10.1007%2fs00382-019-04855-5&partnerID=40&md5=2863b2a6516841872638aa814bc9b1de","Sea surface temperature errors that develop after 1 week are investigated as a function of resolution using retrospective forecasts from the Community Climate System Model. One version resolves the ocean and atmosphere to approximately 1° while the second version resolves the ocean to 0.1° and the atmosphere to 0.5°. The forecasts are initialized on January 1 from 1982 to 2003. The spatial pattern of the Pacific basin sea surface temperatures errors after 1 week is mostly similar at both resolutions, with the exception of the coast of South America. The coastal ocean surface cools within the higher-resolution simulations but warms within the lower-resolution simulations. The difference in the ocean surface temperature is instead attributed to differing changes in the upwelling. Coastal upwelling increases within the higher-resolution simulation, increasing the lower tropospheric stability and encouraging the cloud cover. In contrast, the upwelling decreases within the lower-resolution simulations at 27°S, allowing the ocean surface to warm in spite of cooling from the atmosphere. In both simulations, the northward winds and surface currents weaken, because the South Pacific sea level pressure high moves westward. The increased oceanic upwelling in the high-resolution simulation is instead attributed to an increase in the westward zonal currents. The high-resolution model resolves the narrow Humboldt current, while the low-resolution model does not. This study demonstrates that the processes responsible for SST errors in eastern upwelling boundary current regions change when the oceanic grid spacing becomes fine enough to allow resolution of the oceanic boundary currents. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "16027722300;57210466918;36918071700;56085586900;6701746829;8282604500;","Different determinants of radiation use efficiency in cold and temperate forests",2019,"10.1111/geb.12985","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070794354&doi=10.1111%2fgeb.12985&partnerID=40&md5=75c91bd7c8faec4bf00c149046390975","Aim: To verify which vegetation and environmental factors are the most important in determining the spatial and temporal variability of average and maximum values of radiation use efficiency (RUEann and RUEmax, respectively) of cold and temperate forests. Location: Forty-eight cold and temperate forests distributed across the Northern Hemisphere. Major taxa studied: Evergreen and deciduous trees. Time period: 2000–2011. Methods: We analysed the impact of 17 factors as potential determinants of mean RUE (at 8 days interval, annual and interannual level) and RUEmax (at annual and interannual level) in cold and temperate forests by using linear regression and random forests models. Results: Mean annual RUE (RUEann, c. 1.1 gC/MJ) and RUEmax (c. 0.8 gC/MJ) did not differ between cold and temperate forests. However, for cold forests, RUEann was affected by temperature-related variables, while for temperate forests RUEann was affected by drought-related variables. Leaf area index (LAI) was important for both forest types, while N deposition only for cold forests and cloud cover only for temperate forest. RUEmax of cold forests was mainly driven by N deposition and LAI, whereas for temperate forests only a weak relationship between RUEmax and CO2 concentration was found. Short-term variability of RUE was strongly related to the meteorological variables and varied during the season and was stronger in summer than spring or autumn. Interannual variability of RUEann and RUEmax was only weakly related to the interannual variability of the environmental drivers. Main conclusions: Cold and temperate forests show different relationships with the environment and vegetation properties. Among the RUE drivers observed, the least anticipated was N deposition. RUE is strongly related to short-term and seasonal changes in meteorological variables among seasons and among sites. Our results should be considered in the formulation of climate zone-specific tools for remote sensing and global models. © 2019 The Authors. Global Ecology and Biogeography published by John Wiley & Sons Ltd" "57003664000;6602501070;7003495982;22950200400;","Simulation of wet and dry West African monsoon rainfall seasons using the Weather Research and Forecasting model",2019,"10.1007/s00704-019-02912-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068345258&doi=10.1007%2fs00704-019-02912-x&partnerID=40&md5=9a5632355a6c3c17a251798ed5b0197b","This paper presents an evaluation of the Weather Research and Forecasting (WRF) model in simulating wet and dry West African monsoon (WAM) rainfall seasons. Three model experiments with varying selected microphysics (MP), cumulus convection (CU), and planetary boundary layer (PBL) schemes based on previous study were performed. Each of the model combinations is used to run four WAM seasons that consist of two wet (2008 and 2010) and two dry years (2001 and 2011). To investigate the behavior of WAM in the context of wet and dry years, the four seasons were used to compute composites of wet and dry WAM seasons in terms of rainfall amount. The analyses majorly focus on the rainfall composites relative to rainfall from Global Precipitation Climatology Project (GPCP) and Tropical Rainfall Measurement Mission (TRMM) as well as temperature, moisture, and atmospheric circulation fields with respect to NCEP reanalyses. This study documents significant sensitivity in simulation of the West African monsoon to the choices of the MP, CU, and PBL schemes. The simulation with the combination of WRF single moment 5 (WSM5) MP, Yonsei University (YSU) PBL, and new Simplified Arakawa-Schubert CU (WSM5-YSU-nSAS) shows good spatial distribution pattern of rainfall and the dynamics associated with the monsoon. Quantitatively, the combination shows less agreement in distinguishing the selected WAM seasons compared with the Goddard MP, Mellor-Yamada-Janjic PBL, and Betts-Miller-Janjić CU (GD-MYJ-BMJ) and the WSM5, Mellor-Yamada-Nakanishi-Niino 2.5 level and new Tiedtke CU (WSM5-MYNN-nTDK). Also, the dynamical structures of the wet and dry WAM circulation composites are reasonably reproduced in GD-MYJ-BMJ and WSM5-YSU-nSAS. The GD-MYJ-BMJ was able to distinguish between wet and dry years and thus underscores its potential to reproduce climate change signals in future work. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature." "56542536900;57218181512;57208887679;56130488100;","Assessment of two intense dust storm characteristics over Indo – Gangetic basin and their radiative impacts: A case study",2019,"10.1016/j.atmosres.2019.05.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066051927&doi=10.1016%2fj.atmosres.2019.05.011&partnerID=40&md5=ef1800228858a684c9efeec7d44261f1","The present study is focused to examine the impacts of two intense dust storms on aerosol characteristics and their radiative impacts occurred in pre-monsoon season of 2018 (i.e. 17 May and 14 June 2018) over Kanpur (26.51° N, 80.23° E, 123 above msl). Moderate Resolution Imaging Spectroradiometer (MODIS) true colour images, trajectory pathways of dust storm along with satellite observation and AErosol RObotic NETwork (AERONET) measurements confirms that both the dust storms are either originated from or transported over the Thar Desert, causing a higher aerosol loading which spread over entire Indian-Gangetic Basin (IGB) and modifying the aerosol optical (i.e. aerosol optical depth, angstrom exponent, refractive index etc.), physical (i.e. size distribution) and radiative properties (i.e. single scattering albedo, asymmetric parameter). The space-borne Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) - retrieved aerosol measurements reveal the presence of elevated dust/polluted dust aerosol (up to 3–5 km) over IGB which is well corroborated with aerosol characteristics observed by MODIS, Ozone Monitoring Instrument (OMI) and Atmospheric Infrared Sounder (AIRS). The Dust Regional Atmospheric Model (DREAM8b) shows a good agreement with satellite retrievals with higher value of surface dust concentration in the range of 320–640 μg/m3 over Kanpur during the dust storm days. An enhancement in monthly mean outgoing longwave radiation (up to 60 Wm−2) is observed over IGB and downwind flow region during the dust storm days. The atmospheric aerosol radiative forcing is found 124 Wm−2 and 84 Wm−2 during both the dust storm days (17 May and 14 June 2018) associated with heating rate 2.69 K day−1 and 1.84 K day−1 respectively which may be significant to affect the regional atmospheric dynamics and hence the climate system also. © 2019" "57202333362;55373025000;54925973300;","Effect of teleconnected land-atmosphere coupling on northeast China persistent drought in spring-summer of 2017",2019,"10.1175/JCLI-D-19-0175.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074935673&doi=10.1175%2fJCLI-D-19-0175.1&partnerID=40&md5=006b6a3a55911e269f8888095bf91af3","Northeast China (NEC) suffered a severe drought that persisted from March to July of 2017 with profound impacts on agriculture and society, raising an urgent need to understand the mechanism for persistent droughts over midlatitudes. Previous drought mechanism studies focused on either large-scale teleconnections or local land- atmosphere coupling, while less attention was paid to their synergistic effects on drought persistence.Here we show that the 2017 NEC drought was triggered by a strong positive phase of the Arctic Oscillation in March, and maintained by the anticyclone over the area south toLakeBaikal (ASLB) through a quasi-stationary Rossbywave in April-July, accompanied by sinking motion and north wind anomaly. By using a land-atmosphere coupling index based on the persistence of positive feedbacks between the boundary layer and land surface,we find that the coupling states over NEC and ASLB shifted from a wet coupling in March to a persistently strengthened dry coupling in April-July.Over ASLB, the dry coupling and sinking motion increased surface sensible heat, decreased cloud cover, and weakened longwave absorption, resulting in a diabatic heating anomaly in the lower atmosphere and a diabatic cooling anomaly in the upper atmosphere. This anomalous vertical heating profile led to a negative anomaly of potential vorticity at low levels, indicating that the land-atmosphere coupling had a phase-lock effect on the Rossby wave train originating from upstream areas, and therefore maintained the NEC drought over downstream regions. Our study suggests that an upstream quasi-stationary wave pattern strengthened by land-atmosphere coupling should be considered in diagnosing persistent droughts, especially over northern midlatitudes. © 2019 American Meteorological Society." "55522418000;35205746400;57210918921;57211877504;55339621400;57205504542;35975857100;","Stable isotopes of atmospheric water vapour and precipitation in the northeast Qinghai-Tibetan Plateau",2019,"10.1002/hyp.13541","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071838218&doi=10.1002%2fhyp.13541&partnerID=40&md5=1b834007202e497894f87137c22688f0","Stable water isotopes (δ18O and δ2H) are an important source signature for understanding the hydrological cycle and altered climate regimes. However, the mechanisms underlying atmospheric water vapour isotopes in the northeast Qinghai-Tibetan Plateau of central Asia remain poorly understood. This study initially investigated water vapour isotopic composition and its controls during the premonsoon and monsoon seasons. Isotopic compositions of water vapour and precipitation exhibited high variability across seasons, with the most negative average δ18O values of precipitation and the most positive δ18O values of water vapour found during the premonsoon periods. Temperature effect was significant during the premonsoon period but not the monsoon period. Both a higher slope and intercept of the local meteoric water line were found during the monsoon period as compared with in the premonsoon period, suggesting that raindrops have been experienced a greater kinetic fractionation process such as reevaporation below the cloud during the premonsoon periods. The δ2H and δ18O signatures in atmospheric water vapour tended to be depleted with the occurrence of precipitation events especially during the monsoon period and probably as a result of rainout processes. The monthly average contribution of evaporation from the lake to local precipitation was 35.2%. High d-excess values of water vapour were influenced by the high proportion of local moisture mixing, as indicated by the gradually increasing relative humidity along westerly and Asian monsoon trajectories. The daily observation (observed ε) showed deviations from the equilibrium fractionation factors (calculated ε), implying that raindrops experienced substantial evaporative enrichment during their descent. The average fraction of raindrops reevaporation was estimated to be 16.4± 12.9%. These findings provide useful insights for understanding the interaction between water vapour and precipitation, moisture sources, and help in reconstructing the paleoclimate in the alpine regions. © 2019 John Wiley & Sons, Ltd." "56421138000;57209045965;15844152500;57218184308;26643408200;56875074100;57201456609;57203255846;7404764644;","Evapotranspiration data product from NESDIS GET-D system upgraded for GOES-16 ABI observations",2019,"10.3390/rs11222639","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075401627&doi=10.3390%2frs11222639&partnerID=40&md5=592c1cb92be828089ca23626aa0c59b5","Evapotranspiration (ET) is a major component of the global and regional water cycle. An operational Geostationary Operational Environmental Satellite (GOES) ET and Drought (GET-D) product system has been developed by the National Environmental Satellite, Data and Information Service (NESDIS) in the National Oceanic and Atmospheric Administration (NOAA) for numerical weather prediction model validation, data assimilation, and drought monitoring. GET-D system was generating ET and Evaporative Stress Index (ESI) maps at 8 km spatial resolution using thermal observations of the Imagers on GOES-13 and GOES-15 before the primary operational GOES satellites transitioned to GOES-16 and GOES-17 with the Advanced Baseline Imagers (ABI). In this study, the GET-D product system is upgraded to ingest the thermal observations of ABI with the best spatial resolution of 2 km. The core of the GET-D system is the Atmosphere-Land Exchange Inversion (ALEXI) model, which exploits the mid-morning rise in the land surface temperature to deduce the land surface fluxes including ET. Satellite-based land surface temperature and solar insolation retrievals from ABI and meteorological forcing from NOAA NCEP Climate Forecast System (CFS) are the major inputs to the GET-D system. Ancillary data required in GET-D include land cover map, leaf area index, albedo and cloud mask. This paper presents preliminary results of ET from the upgraded GET-D system after a brief introduction of the ALEXI model and the architecture of GET-D system. Comparisons with in situ ET measurements showed that the accuracy of the GOES-16 ABI based ET is similar to the results from the legacy GET-D ET based on GOES-13/15 Imager data. The agreement with the in situ measurements is satisfactory with a correlation of 0.914 averaged from three Mead sites. Further evaluation of the ABI-based ET product, upgrade efforts of the GET-D system for ESI products, and conclusions for the ABI-based GET-D products are discussed. © 2019 by the authors." "25031310900;57192691929;57211627086;34976267400;23469364700;6602377428;","Satellite retrieval of downwelling shortwave surface flux and diffuse fraction under All Sky Conditions in the framework of the LSA SAF Program (Part 2: Evaluation)",2019,"10.3390/rs11222630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074670253&doi=10.3390%2frs11222630&partnerID=40&md5=5bd30baceae3e8e4de3aa963599161e7","High frequency knowledge of the spatio-temporal distribution of the downwelling surface shortwave flux (DSSF) and its diffuse fraction (fd) at the surface is nowadays essential for understanding climate processes at the surface-atmosphere interface, plant photosynthesis and carbon cycle, and for the solar energy sector. The European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility for Land Surface Analysis operationally delivers estimation of the MDSSFTD (MSG Downwelling Surface Short-wave radiation Fluxes-Total and Diffuse fraction) product with an operational status since the year 2019. The method for retrieval was presented in a companion paper. Part 2 now focuses on the evaluation of the MDSSFTD algorithm and presents a comparison of the corresponding outputs, i.e., total DSSF and diffuse fraction (fd) components, against in situ measurements acquired at four Baseline Surface Radiation Network (BSRN) stations over a seven-month period. The validation is performed on an instantaneous basis. We show that the satellite estimates of DSSF and fd meet the target requirements defined by the user community for all-sky (clear and cloudy) conditions. For DSSF, the requirements are 20 Wm-2 for DSSF < 200 Wm-2, and 10% for DSSF ≥ 200 Wm-2. The mean bias error (MBE) and relative mean bias error (rMBE) compared to the ground measurements are 3.618 Wm-2 and 0.252%, respectively. For fd, the requirements are 0.1 for fd < 0.5, and 20% for fd ≥ 0.5. The MBE and rMBE compared to the ground measurements are -0.044% and -17.699%, respectively. The study also provides a separate analysis of the product performances for clear sky and cloudy sky conditions. The importance of representing the cloud-aerosol radiative coupling in the MDSSFTD method is discussed. Finally, it is concluded that the quality of the aerosol optical depth (AOD) forecasts currently available is accurate enough to obtain reliable diffuse solar flux estimates. This quality of AOD forecasts was still a limitation a few years ago. © 2019 by the authors." "57211332879;57209458625;57211339175;56468006400;35362551800;57190387098;","Numerical simulation of extreme dust storms in east of Iran by the WRF-Chem model",2019,"10.1007/s11069-019-03773-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073559303&doi=10.1007%2fs11069-019-03773-3&partnerID=40&md5=37a738a88717772ab818ceb640841f91","Iran, located in the desert belt, is characterized by frequently increasing sand and dust storms, especially in the eastern and southern areas and creating adverse environmental effects. Efficient management of these devastating events requires an understanding of their features. One way to understand the dust phenomenon is to simulate and predict. The general purpose of the article is to simulate severe storms in the southeast of the country (120-day-old winds) due to the weather conditions of the region and the display of their source and range inside Iran. Aim of this study: Weather Research and Forecasting-Chemistry coupled model (WRF-Chem.3.6.1) is used to simulate, forecast, and design an alert system for sand and dust storm events (east of Iran). Dust concentration data were collected by Environmental Protection Organization, wind speed and direction data were gathered from the Meteorological Organization, MODIS images, and HYSPLIT model forecast was also used to investigate the path of storms and more accurately forecast and time alerting. Results showed that the main dust emission source in Sistan is the dry bed of the Hamoon wetland. Also during the storms that investigated in this study, transport of dust clouds were observed in the southern part of Iran up to Oman sea because of converging currents (north–south winds in the eastern part of Iran, especially in spring and summer) that create strong winds in lower levels of the atmosphere. The WRF-Chem model had reasonable estimations related to spatial and temporal scales in the study area. Using the global forecasted data as model input data, it was expected to observe bias in concentration estimation versus reality. The model was run for 10 and 30 km spatial resolutions, and results revealed storm formation in Sistan was affected by local geographical properties especially topography features. Based on the results obtained and the experience gained, it can be concluded that most dust storms in the Sistan region began in the late spring and will continue until early autumn season. © 2019, Springer Nature B.V." "57197568533;55901813900;57198180671;","The impact of climate change on water fluxes in a Macaronesian cloud forest",2019,"10.1002/hyp.13523","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068341908&doi=10.1002%2fhyp.13523&partnerID=40&md5=2e544832e160a91b096970da95813a8a","Fog phenomena and their associated meteorological variables were continuously monitored during 4 years in an evergreen laurisilva cloud forest of the Anaga Massif Biosphere Reserve (Tenerife, Canary Islands), in order to establish its current dynamics. Fog was more frequent during night through early morning and in the afternoon, and particularly from May until September, coincidental with a frequent immersion of the 1025 m a.s.l. experimental site in the cloud layer of wind-driven stratocumulus. The concomitant meteorological conditions during different fog regimes, characterized according to visibility (Ω) ranges, were compared with those when fog was absent. The presence of fog was associated with a significant reduction in global solar radiation, Rg, increased wind speed, and lower and more stable ambient temperatures. The foggy versus fog-free hourly medians of Rg were found to be linearly related, whereas the proportion of median Rg reduction due to fog varied logarithmically with Ω. However, foggy versus fog-free extreme values of the hourly Rg distributions departed from such a linear trend. By contrast, hourly temperatures during foggy versus fog-free periods behaved linearly for most of the Ω range, except for very dense fog, Ω ≤ 100 m. Transpiration of the canopy, intermittently wetted due to interception of both rain and fog water droplets, was determined by quantifying the water balance at leaf scale with a mathematical model for the two representative hypostomatous species present at the site: the arboreal shrub Erica platycodon, with needle-like leaves, and the laurophyll tree Myrica faya. Both tree transpiration and evaporation of the intercepted fog water were predictively higher during summer. By contrast, transpiration was reduced during February, in agreement with a 1 year period of sap velocity measurements, and was not appreciably affected by soil moisture content. The consequences of an anticipated downward shift of the stratocumulus cloud layer and of various projected Representative Concentration Pathways (RCPs) scenarios in the Macaronesian area were simulated, yielding in all cases a significant rise in transpiration for both species. Particularly, the simulated RCPs scenarios implied 29%–73% increments in transpiration from the actual values. Because fog is concomitant with lower temperatures and vapour pressure deficit, the modification of its current distribution as a consequence of climate change may have a direct effect on such associated meteorological variables, and therefore a meaningful impact in the water relations of the laurel cloud forests. © 2019 John Wiley & Sons, Ltd." "57210983276;57203874192;56306157400;26531794000;55226243300;41361927700;7004677540;8600041800;7006252685;8404544300;","Characterisation of the filter inlet system on the FAAM BAe-146 research aircraft and its use for size-resolved aerosol composition measurements",2019,"10.5194/amt-12-5741-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072104082&doi=10.5194%2famt-12-5741-2019&partnerID=40&md5=5b17addec395b2eadbdabf61cfe253ef","Atmospheric aerosol particles are important for our planetfs climate because they interact with radiation and clouds. Hence, having characterised methods to collect aerosol from aircraft for detailed offline analysis are valuable. However, collecting aerosol, particularly coarsemode aerosol, onto substrates from a fast-moving aircraft is challenging and can result in both losses and enhancement in particles. Here we present the characterisation of an inlet system designed for collection of aerosol onto filters on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146-301 Atmospheric Research Aircraft. We also present an offline scanning electron microscopy (SEM) technique for quantifying both the size distribution and sizeresolved composition of the collected aerosol. We use this SEM technique in parallel with online underwing optical probes in order to experimentally characterise the efficiency of the inlet system. We find that the coarse-mode aerosol is sub-isokinetically enhanced, with a peak enhancement at around 10 μm up to a factor of 2 under recommended operating conditions. Calculations show that the efficiency of collection then decreases rapidly at larger sizes. In order to minimise the isokinetic enhancement of coarse-mode aerosol, we recommend sampling with total flow rates above 50 L min-1 operating the inlet with the bypass fully open helps achieve this by increasing the flow rate through the inlet nozzle.With the inlet characterised, we also present single-particle chemical information obtained from X-ray spectroscopy analysis, which allows us to group the particles into composition categories. © 2019 Author(s)." "55342097000;57209473462;12807577800;57203586491;57201912839;","Regional Climate Effects of Biomass Burning and Dust in East Asia: Evidence From Modeling and Observation",2019,"10.1029/2019GL083894","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074612674&doi=10.1029%2f2019GL083894&partnerID=40&md5=0559745247667ce7e198831d2ebba58b","This study integrates data from regional model simulations, reanalysis data set, radiosonde observations, lidar measurements, and satellite products to evaluate the direct radiative forcing effect of biomass burning and dust over East Asia. During March and April, we find an overall cooling effect of the dust of −5 to −9 W/m2. Biomass burning aerosols from Peninsular Southeast Asia exhibit a warming effect of 5–10 W/m2 over the source area, lower than that over the downwind area of 10–20 W/m2 because of significantly higher cloud coverage in South China. Dust and biomass burning aerosols are found to cool the near surface layer (0–1 km) by −0.5 and −0.3 K, respectively, and warm the upper air (1–5 km) by +0.1 and +0.2 K, respectively. In Taipei, simultaneous presences of dust and biomass burning lead to cooling of near-surface air by −1.5 K and warming of upper air by +1 K. ©2019. American Geophysical Union. All Rights Reserved." "55682751100;57193994250;24081268200;6603180620;14830593700;55915046600;8084443000;","New particle formation in the volcanic eruption plume of the Piton de la Fournaise: Specific features from a long-term dataset",2019,"10.5194/acp-19-13243-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072258502&doi=10.5194%2facp-19-13243-2019&partnerID=40&md5=7d708ce629de937a4c0aab1b33cd04a8","New particle formation (NPF) is a key atmospheric process which may be responsible for a major fraction of the total aerosol number burden at the global scale, including in particular cloud condensation nuclei (CCN). NPF has been observed in various environments around the world, but some specific conditions, such as those encountered in volcanic plumes, remain poorly documented in the literature. Yet, understanding such natural processes is essential to better define pre-industrial conditions and their variability in climate model simulations. Here we report observations of NPF performed at the high-altitude observatory of Maido (2165ma.s.l., La Réunion Island) between 1 January and 31 December 2015. During this time period, three effusive eruptions of the Piton de la Fournaise, located - 39 km away from the station, were observed and documented, resulting in 29 d of measurement in volcanic plume conditions to be compared with 250 ""non-plume days"". This dataset is, to our knowledge, the largest ever reported for the investigation of NPF in tropospheric volcanic plume conditions, and it allowed for the first time a statistical approach to characterize the process and also assessment of its relevance with respect to non-plume conditions. NPF was observed on 90%of the plume days vs. 71% of the non-plume days during the 4 months when the eruptions occurred. The events were on average detected earlier on plume days, most likely benefiting from larger amounts of precursors available at the site prior to nucleation hours. The overall effect of the plume conditions on the particle growth rate was limited. However, with the exception of September, particle formation rates were significantly higher on plume days. The signature of the volcanic plume on the aerosol spectra up to dp D 600 nm was further investigated based on the analysis and fitting of the particle size distributions recorded under in-plume and offplume conditions. The spectra recorded prior to nucleation hours, in the absence of freshly formed particles, featured a significant contribution of particles likely formed via heterogeneous processes at the vent of the volcano (and assimilated to volcanic primary particles) to the concentrations of the two accumulation modes on plume days. Later on in the morning, the concentrations of the nucleation and Aitken modes showed important variations on plume days compared to event days outside of plume conditions. The spectra recorded on event days, under in-plume and off-plume conditions, were further used to provide an average size distribution of the particles of volcanic origin, which clearly highlighted the dominant contribution of secondary over primary particles (93 %) to the total concentration measured on NPF event days within a volcanic plume. In a next step, particular attention was paid to the concentration of particles with dp > 50 nm (N50), used as a proxy for potential CCN population. The contribution of secondary particles to the increase in N50 was the most frequent in plume conditions, and the magnitude of the increase was also more important on plume days compared to non-plume days. Finally, in order to further evaluate the effect of volcanic plume conditions on the occurrence of NPF, we analysed the variations of the condensation sink (CS) and [H2SO4], previously reported to play a key role in the process. Over the investigated months, higher CS (calculated prior to nucleation hours) were observed in plume conditions and coincided with high SO2 mixing ratios. Those most likely compensated for the strengthened loss rate of the vapours and favoured the occurrence of NPF, suggesting at the same time a key role of H2SO4 in the process. This last hypothesis was further supported by the correlation between the formation rate of 2 nm particles (J2) and [H2SO4], and by the fair approximation of J2 that was obtained by means of a recent parameterization of the binary nucleation of H2SO4- H2O. This last result demonstrates that in the absence of direct measurements of [H2SO4] and sub-3 nm particle concentrations, estimates of J2 could be fairly estimated from the knowledge of SO2 mixing ratios only. Finally, the use of the parameterization for ion-induced binary nucleation also highlighted the likely significant contribution of ion-induced nucleation for [H2SO4] below 8-108 cm-3. © Author(s) 2019." "56974040800;10240213900;7402737522;56262351900;57203053317;","Effects of land use and anthropogenic aerosol emissions in the Roman Empire",2019,"10.5194/cp-15-1885-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074423406&doi=10.5194%2fcp-15-1885-2019&partnerID=40&md5=22556f41621b262f854063c6c9f407d9","As one of the first transcontinental polities that led to widespread anthropogenic modification of the environment, the influence of the Roman Empire on European climate has been studied for more than 20 years. Recent advances in our understanding of past land use and aerosol-climate interactions make it valuable to revisit the way humans may have affected the climate of the Roman era. Here we estimate the effect of humans on some climate variables in the Roman Empire at its apogee, focusing on the impact of anthropogenic land cover and aerosol emissions. For this we combined existing land use scenarios with novel estimates (low, medium, high) of aerosol emissions from fuel combustion and burning of agricultural land. Aerosol emissions from agricultural burning were greater than those from fuel consumption but of the same order of magnitude. Using the global aerosol-enabled climate model ECHAM-HAM-SALSA, we conducted simulations with fixed sea-surface temperatures to gain a first impression about the possible climate impact of anthropogenic land cover and aerosols in the Roman Empire. While land use effects induced a regional warming for one of the reconstructions caused by decreases in turbulent flux, aerosol emissions enhanced the cooling effect of clouds and thus led to a cooling in the Roman Empire. Quantifying the anthropogenic influence on climate is, however, challenging since our model likely overestimates aerosol-effective radiative forcing and prescribes the sea-surface temperatures. © 2019 Author(s)." "57210644550;8683346200;","Review of the sky temperature and solar decomposition and their impact on thermal modeling",2019,"10.1080/23744731.2019.1629242","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071156084&doi=10.1080%2f23744731.2019.1629242&partnerID=40&md5=2f830d941c876e0131b6c537b068b8ff","Performing accurate hourly building energy modeling requires the presence of reliable boundary conditions. The required data for energy simulation model entries are exterior air temperature, exterior air relative humidity, solar radiation, sky temperature, wind velocity, and cloud cover. Unfortunately, most available measured solar energy data is in the form of global horizontal radiation. Moreover, measured night sky temperature is normally not available. Proper energy modeling of a full building requires having accurate solar radiation intensity on angled building envelope surfaces as well as precise sky temperature data available. In this study, among several available models, three hourly horizontal global solar radiation decomposition models, four hourly diffuse radiation models on an inclined surface, and five sky temperature estimation models are studied for the Vancouver, Canada, climate. For the purpose of solar radiation validation, 2013 1-year measured total solar radiation on a southeast-oriented wall located at the British Columbia Institute of Technology Burnaby Campus is compared with the results from selected solar models. For both solar radiation and sky temperature models, the impact of using different models on transient heat transfer results of lightweight and mass-type walls (two walls) are reviewed. Results reveal the high impact of both solar and sky temperature models on hourly heat transfer simulation results. © 2019, Copyright © 2019 ASHRAE." "19639722300;56646265500;35612769500;57195758560;7203054240;57194439276;57202311131;8686475900;","Land-atmosphere interactions in the tropics - A review",2019,"10.5194/hess-23-4171-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073711922&doi=10.5194%2fhess-23-4171-2019&partnerID=40&md5=9374a01b29b22b38148d6a612a0654ff","The continental tropics play a leading role in the terrestrial energy, water, and carbon cycles. Land-atmosphere interactions are integral in the regulation of these fluxes across multiple spatial and temporal scales over tropical continents. We review here some of the important characteristics of tropical continental climates and how land-atmosphere interactions regulate them. Along with a wide range of climates, the tropics manifest a diverse array of land-atmosphere interactions. Broadly speaking, in tropical rainforest climates, light and energy are typically more limiting than precipitation and water supply for photosynthesis and evapotranspiration (ET), whereas in savanna and semi-arid climates, water is the critical regulator of surface fluxes and land-atmosphere interactions. We discuss the impact of the land surface, how it affects shallow and deep clouds, and how these clouds in turn can feed back to the surface by modulating surface radiation and precipitation. Some results from recent research suggest that shallow clouds may be especially critical to land-atmosphere interactions. On the other hand, the impact of land-surface conditions on deep convection appears to occur over larger, nonlocal scales and may be a more relevant land-atmosphere feedback mechanism in transitional dry-to-wet regions and climate regimes. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License." "55704590100;7005902717;","Quantifying the Cloud Particle-Size Feedback in an Earth System Model",2019,"10.1029/2019GL083829","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074194066&doi=10.1029%2f2019GL083829&partnerID=40&md5=65b778e1a6e4fb4464ba3e3e586de066","Physical process-based two-moment cloud microphysical parameterizations, in which effective cloud particle size evolves prognostically with climate change, have recently been incorporated into global climate models. The impacts of cloud particle-size change on the cloud feedback, however, have never been explicitly quantified. Here we develop a partial radiative perturbation-based method to estimate the cloud feedback associated with particle-size changes in the Community Earth System Model. We find an increase of cloud particle size in the upper troposphere in response to an instantaneous doubling of atmospheric CO2. The associated net, shortwave, and longwave cloud feedbacks are estimated to be 0.18, 0.33, and −0.15 Wm−2 K−1, respectively. The cloud particle-size feedback is dominated by its shortwave component with a maximum greater than 1.0 Wm−2 K−1 in the tropics and the Southern Ocean. We suggest that the cloud particle-size feedback is an underappreciated contributor to the spread of cloud feedback and climate sensitivity among current models. ©2019. American Geophysical Union. All Rights Reserved." "55901813900;57197568533;","On the estimation of potential fog water collection from meteorological variables",2019,"10.1016/j.agrformet.2019.107645","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068323896&doi=10.1016%2fj.agrformet.2019.107645&partnerID=40&md5=73dbdab46d1f69fa830b7d7d1c1b9560","We provide a method for estimating potential fog water collection (FWCp) from concomitant measurements of visibility (Ω) and wind speed (u). Various passive artificial fog catcher assemblies, wire-harps and screens with cylindrical geometry and uni- or omni-directional square flat gauges, placed at two fog-affected sites in Tenerife (Canary Islands, Spain), were used for calibrating an empirical model of FWCp vs. u-Ω with good fitting performance (0.762 ≤ NSE ≤ 0.921; 0.063 l m−2 ≤ RMSE ≤ 0.247 l m-2). The procedure may be useful for characterization of locations for fog water exploitation, forest fog interception or potential cloud forest distribution. © 2019 Elsevier B.V." "56966180500;7006143750;","Effects of urban and landscape elements on air temperature in a high-density subtropical city",2019,"10.1016/j.buildenv.2019.106362","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071401512&doi=10.1016%2fj.buildenv.2019.106362&partnerID=40&md5=b9df9d733533ab1469e29ba9259fd2fb","In this study, we examined the effects of key urban (road cover, building volume ratio, and proximity to sea) and landscape (water body, tree cover, shrub cover, turf cover, park area, and sky view factor) parameters on air temperature, and the impacts of weather conditions on landscape-temperature relationship. One hundred temperature sensors were installed in fourteen urban parks in Hong Kong during summer season to collect continuous air temperature data. Linear mixed-effect models showed that the effects of weather (cloud amount, solar radiation and wind speed) on landscape-temperature relationships were minor (<0.2 °C). Therefore, the landscape effects were further investigated using the entire dataset regardless of weather conditions. In a circular buffer zone with a 20-m radius, a 10% increase in road density caused a 0.059 °C rise in daytime mean air temperature while the same increase in tree cover and shrub cover led to a 0.052 and 0.041 °C drop in temperature, respectively. A 0.849 °C rise could be expected when sky view factor increased from 0 to 1. The proximity to the sea also had a significant daytime cooling effect (0.784 °C/1000 m). The night-time landscape effects were similar to the daytime except that the strengths of the effects on air temperature were weaker. The obtained results can be used by landscape designers and urban planners for modifying the landscape to bring cooling effects and tackle heat-island and climate-change impacts. © 2019 Elsevier Ltd" "55735405000;12801073500;56681868600;","Importance of the advection scheme for the simulation of water isotopes over Antarctica by atmospheric general circulation models: A case study for present-day and Last Glacial Maximum with LMDZ-iso",2019,"10.1016/j.epsl.2019.115731","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069967812&doi=10.1016%2fj.epsl.2019.115731&partnerID=40&md5=a55d4276af7796a2e57cf8191b849938","Atmospheric general circulation models (AGCMs) are known to have a warm and isotopically enriched bias over Antarctica. We test here the hypothesis that these biases are partly consequences of a too diffusive advection. Exploiting the LMDZ-iso model, we show that a less diffusive representation of the advection, especially on the horizontal, is very important to reduce the bias in the isotopic contents of precipitation above this area. The choice of an appropriate representation of the advection is thus essential when using GCMs for paleoclimate applications based on polar water isotopes. Too much diffusive mixing along the poleward transport leads to overestimated isotopic contents in water vapor because dehydration by mixing follows a more enriched path than dehydration by Rayleigh distillation. The near-air surface temperature is also influenced, to a lesser extent, by the diffusive properties of the advection scheme directly via the advection of the air and indirectly via the radiative effects of changes in high cloud fraction and water vapor. A too diffusive horizontal advection increases the temperature and so also contributes to enrich the isotopic contents of water vapor over Antarctica through a reduction of the distillation. The temporal relationship, from Last Glacial Maximum (LGM) to present-day conditions, between the mean annual near-air surface temperature and the water isotopic contents of precipitation for a specific location can also be impacted, with significant consequences on the paleo-temperature reconstruction from observed changes in water isotopes. © 2019 Elsevier B.V." "57201120333;35810148400;36926416100;7004035832;57203106791;","Three dimensional mapping of forest canopy equivalent water thickness using dual-wavelength terrestrial laser scanning",2019,"10.1016/j.agrformet.2019.107627","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067523913&doi=10.1016%2fj.agrformet.2019.107627&partnerID=40&md5=93a832f63fe3611dc1bdeb82c282dc0f","Globally, forests are being subjected to numerous threats, including climate change, wildfires, and insect and disease outbreaks, among others. Satellite optical remote sensing data have been widely utilized in early detection of tree and forest stress by estimating water status metrics such as the leaf Equivalent Water Thickness (EWT). This estimate, however, is affected by soil characteristics and understory vegetation and often ignores the effects of the fine-scale heterogeneity of canopy structure and leaf water content. Such effects can be better understood by studying the EWT distribution in three dimensions. In this study, Terrestrial Laser Scanning (TLS) intensity data from the commercially-available Leica P20 and P40 instruments (808 nm and 1550 nm respectively) were combined in a Normalized Difference Index (NDI). NDI was used to map EWT of 12 trees in three dimensions from floor to canopy in a mixed broadleaf forest plot (Wytham Woods, UK). The average error in EWT estimates across three species was less than 8%. The three dimensional point clouds revealed that, in this snapshot, EWT changes vertically, usually increasing towards canopy top. The proposed method has the potential to provide predawn EWT measurements, is independent of solar illumination, and can lead to a better understanding of the factors affecting satellite estimation of EWT. © 2019 Elsevier B.V." "57193132723;57191693467;7005063241;33367455100;8401913500;36084340100;7102886537;9242539000;36026612000;55155453000;9242540400;","Albedos, Equilibrium Temperatures, and Surface Temperatures of Habitable Planets",2019,"10.3847/1538-4357/ab3be8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073822060&doi=10.3847%2f1538-4357%2fab3be8&partnerID=40&md5=491b4106cbfc94e8198af67da953b774","The potential habitability of known exoplanets is often categorized by a nominal equilibrium temperature assuming a Bond albedo of either ∼0.3, similar to Earth, or 0. As an indicator of habitability, this leaves much to be desired, because albedos of other planets can be very different, and because surface temperature exceeds equilibrium temperature due to the atmospheric greenhouse effect. We use an ensemble of general circulation model simulations to show that for a range of habitable planets, much of the variability of Bond albedo, equilibrium temperature and even surface temperature can be predicted with useful accuracy from incident stellar flux and stellar temperature, two known parameters for every confirmed exoplanet. Earth's Bond albedo is near the minimum possible for habitable planets orbiting G stars, because of increasing contributions from clouds and sea ice/snow at higher and lower instellations, respectively. For habitable M star planets, Bond albedo is usually lower than Earth's because of near-IR H2O absorption, except at high instellation where clouds are important. We apply relationships derived from this behavior to several known exoplanets to derive zeroth-order estimates of their potential habitability. More expansive multivariate statistical models that include currently non-observable parameters show that greenhouse gas variations produce significant variance in albedo and surface temperature, while increasing length of day and land fraction decrease surface temperature; insights for other parameters are limited by our sampling. We discuss how emerging information from global climate models might resolve some degeneracies and help focus scarce observing resources on the most promising planets. © 2019. The American Astronomical Society. All rights reserved." "7402264252;57208132039;35576373500;36515577800;55708036200;12808778700;35098639300;57201030837;15130987300;6507498114;8537480000;57211484825;","Enabling Stakeholder Decision-Making With Earth Observation and Modeling Data Using Tethys Platform",2019,"10.3389/fenvs.2019.00148","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074145220&doi=10.3389%2ffenvs.2019.00148&partnerID=40&md5=cb469ac37084bf3ca4875c18d59fd1a3","Tethys Platform is an open source framework for developing web-based applications for Earth Observation data. Our experience shows that Tethys significantly lowers the barrier for cloud-based app development, simplifies the process of accessing scalable distributed cloud computing resources and leverages additional software for data and computationally intensive modeling. The Tethys software development kit allows users to create web apps for visualizing, analyzing, and modeling Earth Observation data. Tethys platform provides a collaborative environment for scientists to develop and deploy several Earth Observation web applications across multiple Tethys portals. We work in partnership with leading regional organizations world-wide to help developing countries use information provided by earth-observing satellites and geospatial technologies for managing climate risks and land use. This paper highlights the several Tethys portals and web applications that were developed as part of this effort. Implementation of the Tethys framework has significantly improved the Application Readiness Level metric for several NASA projects and the potential impact of Tethys to replicate and scale other applied science programs. © Copyright © 2019 Nelson, Pulla, Matin, Shakya, Jones, Ames, Ellenburg, Markert, David, Zaitchik, Gatlin and Hales." "57190389101;57197749126;12790712700;23394396700;35735226500;7203052598;7006347751;56411079900;","Enhanced heterogeneous uptake of sulfur dioxide on mineral particles through modification of iron speciation during simulated cloud processing",2019,"10.5194/acp-19-12569-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073239675&doi=10.5194%2facp-19-12569-2019&partnerID=40&md5=4d4584c0e87d870fe9b6a35f383eabac","Iron-containing mineral aerosols play a key role in the oxidation of sulfur species in the atmosphere. Simulated cloud processing (CP) of typical mineral particles, such as illite (IMt-2), nontronite (NAu-2), smectite (SWy-2) and Arizona Test Dust (ATD) is shown here to modify sulfur dioxide (SO2) uptake onto mineral surfaces. Heterogeneous oxidation of SO2 on particle surfaces was firstly investigated using an in situ DRIFTS apparatus (diffuse reflectance infrared Fourier transform spectroscopy). Our results showed that the Brunauer-Emmett-Teller (BET) surface area normalized uptake coefficients (γBET) of SO2 on the IMt-2, NAu-2, SWy-2 and ATD samples after CP were 2.2, 4.1, 1.5 and 1.4 times higher than the corresponding ones before CP, respectively. The DRIFTS results suggested that CP increased the amounts of reactive sites (e.g., surface OH groups) on the particle surfaces and thus enhanced the uptake of SO2. Transmission electron microscopy (TEM) showed that the particles broke up into smaller pieces after CP, and thus produced more active sites. The ""free-Fe"" measurements confirmed that more reactive Fe species were present after CP, which could enhance the SO2 uptake more effectively. Mössbauer spectroscopy further revealed that the formed Fe phases were amorphous Fe(III) and nanosized ferrihydrite hybridized with Al = Si, which were possibly transformed from the Fe in the aluminosilicate lattice. The modification of Fe speciation was driven by the pH-dependent fluctuation coupling with Fe dissolution-precipitation cycles repeatedly during the experiment. Considering both the enhanced SO2 uptake and subsequent promotion of iron dissolution along with more active Fe formation, which in turn led to more SO2 uptake, it was proposed that there may be a positive feedback between SO2 uptake and iron mobilized on particle surfaces during CP, thereby affecting climate and biogeochemical cycles. This self-amplifying mechanism generated on the particle surfaces may also serve as the basis of high sulfate loading in severe fog-haze events observed recently in China. © Author(s) 2019." "7004993886;7005634455;7410338331;55813858200;6701873414;7006246996;","Microphysics of summer clouds in central West Antarctica simulated by the Polar Weather Research and Forecasting Model (WRF) and the Antarctic Mesoscale Prediction System (AMPS)",2019,"10.5194/acp-19-12431-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073477091&doi=10.5194%2facp-19-12431-2019&partnerID=40&md5=6dd50228d72cb70afa8e172d3c60c4c9","The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) provided a highly detailed set of remote-sensing and surface observations to study Antarctic clouds and surface energy balance, which have received much less attention than for the Arctic due to greater logistical challenges. Limited prior Antarctic cloud observations have slowed the progress of numerical weather prediction in this region. The AWARE observations from the West Antarctic Ice Sheet (WAIS) Divide during December 2015 and January 2016 are used to evaluate the operational forecasts of the Antarctic Mesoscale Prediction System (AMPS) and new simulations with the Polar Weather Research and Forecasting Model (WRF) 3.9.1. The Polar WRF 3.9.1 simulations are conducted with the WRF single-moment 5-class microphysics (WSM5C) used by the AMPS and with newer generation microphysics schemes. The AMPS simulates few liquid clouds during summer at the WAIS Divide, which is inconsistent with observations of frequent low-level liquid clouds. Polar WRF 3.9.1 simulations show that this result is a consequence of WSM5C. More advanced microphysics schemes simulate more cloud liquid water and produce stronger cloud radiative forcing, resulting in downward longwave and shortwave radiation at the surface more in agreement with observations. Similarly, increased cloud fraction is simulated with the more advanced microphysics schemes. All of the simulations, however, produce smaller net cloud fractions than observed. Ice water paths vary less between the simulations than liquid water paths. The colder and drier atmosphere driven by the Global Forecast System (GFS) initial and boundary conditions for AMPS forecasts produces lesser cloud amounts than the Polar WRF 3.9.1 simulations driven by ERA-Interim. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License." "24280225800;57201069098;36697726500;","The surface albedo of the Greenland Ice Sheet between 1982 and 2015 from the CLARA-A2 dataset and its relationship to the ice sheet's surface mass balance",2019,"10.5194/tc-13-2597-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073460270&doi=10.5194%2ftc-13-2597-2019&partnerID=40&md5=d96ffc4111790647c866e5bd83077300","The Greenland Ice Sheet is losing mass at a significant rate, driven in part by increasing surface-melt-induced runoff. Because the ice sheet's surface melt is closely connected to changes in the surface albedo, studying multidecadal changes in the ice sheet's albedo offers insight into surface melt and associated changes in its surface mass balance. Here, we first analyse the CM SAF Cloud, Albedo and Surface Radiation dataset from AVHRR data second edition (CLARA-A2) Surface Albedo (SAL), covering 1982-2015, to obtain decadal albedo trends for each summer month. We also examine the rates of albedo change during the early summer, supported with atmospheric reanalysis data from MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, version 2), to discern changes in the intensity of early summer melt, and their likely drivers. We find that rates of albedo decrease during summer melt have accelerated during the 2000s relative to the early 1980s and that the surface albedos now often decrease to values typical of bare ice at elevations 50-100 m higher on the ice sheet. The southern margins exhibit the opposite behaviour, though, and we suggest this is due to increasing snowfall over the area. We then subtract ice discharge from the mass balance estimates observed by the Gravity Recovery and Climate Experiment (GRACE) satellite mission to estimate surface mass balance. The CLARA-A2 albedo changes are regressed with these data to obtain a summer-aggregated proxy surface mass balance time series for the summer periods 1982-2015. This proxy time series is compared with latest regional climate model estimates from the MAR model to perform an observation-based test on the dominance of surface runoff in the magnitude and variability of the summer surface mass balance. We show that the proxy time series agrees with MAR through the analysed period within the associated uncertainties of the data and methods, demonstrating and confirming that surface runoff has dominated the rapid surface mass loss period between the 1990s and 2010s. Finally, we extend the analysis to the drainage basin scale to examine discharge-albedo relationships. We find little evidence of surface-melt-induced ice flow acceleration at annual timescales. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License." "54409192400;","Recent expansion of oil palm plantation in the most eastern part of Indonesia: feature extraction with polarimetric SAR",2019,"10.1080/01431161.2018.1508924","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052332013&doi=10.1080%2f01431161.2018.1508924&partnerID=40&md5=5d2558d62a7ca1e8d83471462ba5ca8d","Tropical forest is important in tackling global climate change. However, large-scale transformation of tropical forest in Indonesia is being done for oil palm plantation. Till date, there is a lack of scientific documentation that shows the most recent situation of oil palm plantation in the most eastern part of the country. This study documents the real condition of oil palm plantation expansion based on Sentinel data of European Space Agency (ESA). Sentinel-1 data sets of Papua Provinces of the year 2017 acquisition are used to avoid cloud cover problems in tropical regions. Object-based geospatial data feature extraction with Polarimetric SAR compared to the multiple classifier methods (that is, Gaussian Mixture Method, Random Forest, Support Vector Machine, and K-Nearest Neighbors) were introduced and employed using GRASS & QGIS of free open source software (FOSS). Google Earth Engine (GEE) was then used to verify the classification result of oil palm plantation. The preprocessing step is very crucial in achieving high accuracy. However, it is time-consuming. This study concluded that the proposed method and SVM classifiers achieved the highest accuracy, 99.7% and 99.12%, respectively. While the KNN, RF, and GMM classifier produced 94.63%, 89.06%, and 72.87%, respectively. We found that vast scale transformation of tropical rainforest in lowland areas is happening in eastern Indonesia. This situation should be strictly monitored and controlled to avoid more significant issues related to socio-economic-environmental implications. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group." "57208765667;35069282600;24329376600;7102805852;35794588800;8067118800;55355176000;12645767500;9249239700;57207486814;22986726400;","Cloud physics from space",2019,"10.1002/qj.3589","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071620824&doi=10.1002%2fqj.3589&partnerID=40&md5=3501d789bdc6c65872c7d30518172083","A review of the progression of cloud physics from a subdiscipline of meteorology into the global science it is today is described. The discussion briefly touches on the important post-war contributions of three key individuals who were instrumental in developing cloud physics into a global science. These contributions came on the heels of the post-war weather modification efforts that influenced much of the early development of cloud physics. The review is centred on the properties of warm clouds primarily to limit the scope of the article and the connection between the early contributions to cloud physics and the current vexing problem of aerosol effects on cloud albedo is underlined. Progress toward estimating cloud properties from space and insights on warm cloud processes are described. Measurements of selected cloud properties, such as cloud liquid water path are now mature enough that multi-decadal time series of these properties exist and this climatology is used to compare to analogous low-cloud properties taken from global climate models. The too-wet (and thus too bright) and the too-dreary biases of models are called out underscoring the challenges we still face in representing warm clouds in Earth system models. We also provide strategies for using observations to constrain the indirect radiative forcing of the climate system. © 2019 Royal Meteorological Society" "7004384155;6507506306;57193694921;8937991200;","New Cloud System Metrics to Assess Bulk Ice Cloud Schemes in a GCM",2019,"10.1029/2019MS001642","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074352774&doi=10.1029%2f2019MS001642&partnerID=40&md5=4f836b00c2a3303fdb73400c5b810100","Bulk microphysical properties of ice clouds, such as fall speed and ice crystal size distribution, strongly impact the life time and the radiative effects of these clouds. Three coherent bulk ice schemes, with fall speed and effective ice crystal diameter depending on both ice water content and temperature, have been constructed from published parameterizations. We present a novel upper tropospheric cloud system concept to study the impact of these schemes on the LMDZ climate simulations. For this evaluation, cloud data from hyperspectral infrared sounders Atmospheric InfraRed Sounder and IR Atmospheric Sounding Interferometer are used, because they include cirrus with visible optical depths as low as 0.2. The analogous satellite observation simulator, developed for this purpose, is also presented. The cloud system concept, applied to the data and to the simulator outputs, allows a process-oriented evaluation. In general, the new bulk ice schemes lead to a better agreement with the cloud data, in particular concerning the cloud system property distributions and the relation between cloud system properties and proxies mimicking the life stage and the convective depth. Sensitivity studies have demonstrated that both the introduction of the new schemes as well as the necessary adjustment of the relative width of the upper tropospheric subgrid water distribution lead to these improvements. Our studies also suggest to revise the formulation of the latter. © 2019. The Authors." "7004893330;8378783200;57159374600;7103271625;6603171355;55286185400;50261552200;7006306835;","Extratropical cyclone clouds in the GFDL climate model: Diagnosing biases and the associated causes",2019,"10.1175/JCLI-D-19-0421.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074231021&doi=10.1175%2fJCLI-D-19-0421.1&partnerID=40&md5=0e5d5d850175d64c33b4c90c9a708a23","The clouds in Southern Hemisphere extratropical cyclones generated by the GFDL climate model are analyzed against MODIS, CloudSat, and CALIPSO cloud and precipitation observations. Two model versions are used: one is a developmental version of ‘‘AM4,’’ a model GFDL that will utilize for CMIP6, and the other is the same model with a different parameterization of moist convection. Both model versions predict a realistic top-of-atmosphere cloud cover in the southern oceans, within 5% of the observations. However, an examination of cloud cover transects in extratropical cyclones reveals a tendency in the models to overestimate high-level clouds (by differing amounts) and underestimate cloud cover at low levels (again by differing amounts), especially in the post–cold frontal (PCF) region, when compared with observations. In focusing only on the models, it is seen that their differences in high and midlevel clouds are consistent with their differences in convective activity and relative humidity (RH), but the same is not true for the PCF region. In this region, RH is higher in the model with less cloud fraction. These seemingly contradictory cloud and RH differences can be explained by differences in the cloud-parameterization tuning parameters that ensure radiative balance. In the PCF region, the model cloud differences are smaller than either of the model biases with respect to observations, suggesting that other physics changes are needed to address the bias. The process-oriented analysis used to assess these model differences will soon be automated and shared. © 2019 American Meteorological Society." "54897465300;57203049177;","A refined model for the Earth’s global energy balance",2019,"10.1007/s00382-019-04825-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066627246&doi=10.1007%2fs00382-019-04825-x&partnerID=40&md5=b2a6fda3666ad3641f383a5b079f0b89","A commonly-used model of the global radiative budget assumes that the radiative response to forcing, R, is proportional to global surface air temperature T, R= λT. Previous studies have highlighted two unresolved issues with this model: first, the feedback parameter λ depends on the forcing agent; second, λ varies with time. Here, we investigate the factors controlling R in two atmosphere–slab ocean climate models subjected to a wide range of abrupt climate forcings. It is found that R scales not only with T, but also with the large-scale tropospheric stability S (defined here as the estimated inversion strength area-averaged over ocean regions equatorward of 50∘). Positive S promotes negative R, mainly through shortwave cloud and lapse-rate changes. A refined model of the global energy balance is proposed that accounts for both temperature and stability effects. This refined model quantitatively explains (1) the dependence of climate feedbacks on forcing agent (or equivalently, differences in forcing efficacy), and (2) the time evolution of feedbacks in coupled climate model experiments. Furthermore, a similar relationship between R and S is found in observations compared with models, lending confidence that the refined energy balance model is applicable to the real world. © 2019, The Author(s)." "49664027700;56567409000;35509639400;7201504886;7003865921;55453482000;11939918300;55626648300;22956930200;","A New Look at the Daily Cycle of Trade Wind Cumuli",2019,"10.1029/2019MS001746","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074251680&doi=10.1029%2f2019MS001746&partnerID=40&md5=7a40b718de8004f06fdd7898d3d737b9","A description of the daily cycle of oceanic shallow cumulus for undisturbed boreal winter conditions in the North Atlantic trades is presented. Modern investigation tools are used, including storm-resolving and large-eddy simulations, runover large domains in realistic configurations, and observations from in situ measurements and satellite-based retrievals. Models and observations clearly show pronounced diurnal variations in cloudiness, both near cloud base and below the trade inversion. The daily cycle reflects the evolution of two cloud populations: (i) a population of nonprecipitating small cumuli with weak vertical extent, which grows during the day and maximizes around sunset, and (ii) a population o deeper precipitating clouds with a stratiform cloud layer below the trade inversion, which grows during the night and maximizes just before sunrise. Previous studies have reported that cloudiness near cloud base undergoes weak variations on time scales longer than a day. However, here we find that it can vary strongly at the diurnal time scale. This daily cycle could serve as a critical test of the models' representation of the physical processes controlling cloudiness near cloud base, which is thought to be key for the determination of the Earth's climate response to warming. ©2019. The Authors." "57214315341;57214321345;36109948200;8909274600;6507849745;","Application of spatial technology in Malaria information infrastructure mapping with climate change perspective in Maharashtra, India",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078617118&partnerID=40&md5=92a2e38ac58e483a3c1e75af5acfb3b0","The present research paper proposes Malaria Information Infrastructure Mapping in Maharashtra, India using Cloud Spatial Data Infrastructure (SDI) Model with a perspective on Climate Change. In m-cloud, geospatial health database has been developed for positive cases and that of number of deaths due to Malaria from 2001 to 2014 in Maharashtra, using Open Source GIS software; Quantum GIS and Map Window GIS. Transmission windows (TW) month for malaria was identified for all 35 districts in the state using climate data on temperature, rainfall and humidity. Overlay analysis was carried using the cloud model and different graphs generated. Mosquitoes are active between 20 °C and 34 °C window. However, peak transmission can extend up to 29 °C. Observations of climate data during the last 100 years, over India, show a rising trend in surface temperature by 0.3 °C. As a result, there is a growing concern about the possible resurgence of vector-borne diseases, such as malaria, over some parts of India. Regression analysis of simulated mean temperature based on CORDEX data for the period 2015-2050 over Maharashtra show an increasing trend over Maharashtra until 2050. © 2019, India Meteorological Department. All rights reserved." "57189461717;24468389200;","Vertical Structures of Convective and Stratiform Clouds in Boreal Summer over the Tibetan Plateau and Its Neighboring Regions",2019,"10.1007/s00376-019-8229-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070976767&doi=10.1007%2fs00376-019-8229-4&partnerID=40&md5=ecb678125ef0ac65955682c430294723","Cloud is essential in the atmosphere, condensing water vapor and generating strong convective or large-scale persistent precipitation. In this work, the relationships between cloud vertical macro- or microphysical properties, radiative heating rate, and precipitation for convective and stratiform clouds in boreal summer over the Tibetan Plateau (TP) are analyzed and compared with its neighboring land and tropical oceans based on CloudSat/CALIPSO satellite measurements and TRMM precipitation data. The precipitation intensity caused by convective clouds is twofold stronger than that by stratiform clouds. The vertical macrophysics of both cloud types show similar features over the TP, with the region weakening the precipitation intensity and compressing the cloud vertical expansion and variation in cloud top height, but having an uplift effect on the average cloud top height. The vertical microphysics of both cloud types under conditions of no rain over the TP are characterized by lower-level ice water, ice particles with a relatively larger range of sizes, and a relatively lower occurrence of denser ice particles. The features are similar to other regions when precipitation enhances, but convective clouds gather denser and larger ice particles than stratiform clouds over the TP. The atmospheric shortwave (longwave) heating (cooling) rate strengthens with increased precipitation for both cloud types. The longwave cooling layer is thicker when the rainfall rate is less than 100 mm d−1, but the net heating layer is typically compressed for the profiles of both cloud types over the TP. This study provides insights into the associations between clouds and precipitation, and an observational basis for improving the simulation of convective and stratiform clouds over the TP in climate models. © 2019, Institute of Atmospheric Physics/Chinese Academy of Sciences, and Science Press and Springer-Verlag GmbH Germany, part of Springer Nature." "36740698600;6701718281;","Environmental impacts on the flux of mass through deep convection",2019,"10.1002/qj.3669","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075446967&doi=10.1002%2fqj.3669&partnerID=40&md5=5a50726f112c55a94b6a5750912dfdc0","Though deep convective clouds are important to numerous aspects of the climate system, they remain a source of much uncertainty. The varying large-scale dynamics, relatively short development time, range of spatial scales, and complex microphysics involved in deep convection lead to difficulty in both observation of these clouds and modelling their impacts on larger spatial and longer temporal scales. This study utilizes an ensemble of high-resolution cloud-resolving simulations of deep convection forming in a spectrum of different environments to explore the sensitivity of deep convection, and in particular convective mass flux to changes in the initial conditions. We find that convection strength is strongly sensitive to small perturbations in the environment, specifically the convective available potential energy (CAPE) and boundary-layer humidity. That storm effects on the environment, such as mass transport and tropospheric moistening through detrainment, are sensitive to these initial conditions points to the importance of better representing such parameters in global models. © 2019 Royal Meteorological Society" "57191350057;57203321797;57209822481;57200055610;56028456700;","Vertical distribution of the Asian tropopause aerosols detected by CALIPSO",2019,"10.1016/j.envpol.2019.06.111","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068831830&doi=10.1016%2fj.envpol.2019.06.111&partnerID=40&md5=680f37a716d3c676b3c1bfc4dfe4c8b4","Characterizing the vertical distribution of aerosol optical properties is crucial to reduce the uncertainty in quantifying the radiative forcing and climate effects of aerosols. The analysis of four-year (2007–2010) Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar measurements revealed the existence of tropospheric aerosol layers associated with the Asian summer monsoon. The measurements of five typical aerosol optical and microphysical parameters were used to explore the properties, spatial/vertical distributions, annual evolution of tropopause aerosols over the South Asia region. Results extracted from various latitude-height and longitude-height cross sections of aerosol extinction coefficient at 532 and 1064 nm, backscatter coefficient at 532 nm, and depolarization ratio at 532 nm demonstrated that a large amount of aerosols vertically extended up to the tropopause (12 km) during the monsoon season over the north Arabian Sea, India, north Bay of Bengal, and equatorial Indian Ocean, finally reaching the southeast of the Tibetan Plateau. Convective transport associated with Asian summer monsoon is an important factor controlling the vertical distribution of tropopause aerosols. The evolution of aerosol scattering ratio at 532 nm indicated that from equatorial Indian Ocean to South Asia, there exists an upward tilting and ascending structure of the aerosols layer during the monsoon season, which typically indicates enhanced aerosols over the Asian monsoon region. Information on aerosol size distribution and detailed composition are needed for better understanding the nature and origin of this aerosol layer. Enhancement of the tropopause aerosols should be considered in the future studies in evaluating the regional or global climate systems. Further satellite observations of aerosols and in-situ observations are also urgently needed to diagnose this aerosol layer, which likely originate from anthropogenic emissions. © 2019 Elsevier Ltd" "55736647500;56883995600;57194607547;56604132600;35111810600;55694342800;7006544303;","Spatial patterns of meadow sensitivities to interannual climate variability in the Sierra Nevada",2019,"10.1002/eco.2128","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069893735&doi=10.1002%2feco.2128&partnerID=40&md5=566bdbf8a364435b2ad10da87a6fa3d5","Conservation of montane meadows is a high priority for land and water managers given their critical role in buffering the effects of climate variability and their vulnerability to increasing temperatures and evaporative demands. Recent advances in cloud computing have provided new opportunities to examine ecological responses to climate variability over the past few decades and at large spatial scales. In this study, we characterized the sensitivities (magnitude and direction of the slope) of meadow vegetation responses to interannual variations in climate. We calculated sensitivity as the regression slope between a 31-year (1985–2016) time series of Landsat-derived vegetation indices characterizing late-season vegetation vigour and water balance variables from the Basin Characterization Model. We identified April 1 snowpack as the climate variable the majority of meadows were most sensitive to. We assessed how vegetation sensitivities to snowpack varied with hydrogeomorphic context (e.g., climate, geology, soils, watershed geometry, and land cover) across the Sierra Nevada mountain range using factor analysis to reduce the dimensionality of the hydrogeomorphic data and multiple linear regression to model sensitivity responses. We found that meadow sensitivities to snowpack varied with long-term average meadow climate, indicators of watershed subsurface water storage capacity, and indicators of meadow vegetation composition. Alpine and subalpine meadows with high average annual precipitation but limited catchment subsurface storage exhibited the largest sensitivities. Our results provide a novel regional perspective on spatial patterns of meadow sensitivities to climate variability and the landscape-scale hydrogeomorphic factors that influence late-season water availability in meadow ecosystems in the Sierra Nevada. © 2019 John Wiley & Sons, Ltd." "56120456800;35315853500;6603096324;15071907100;","Weak dependence of future global mean warming on the background climate state",2019,"10.1007/s00382-019-04849-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068177734&doi=10.1007%2fs00382-019-04849-3&partnerID=40&md5=30eb52cfc217b5da9d7b0bb485ecf4a2","It is debated whether the global mean transient temperature response to forcing is largely independent of biases in the simulated base state climate. To test this, we run the Community Earth System Model (CESM1) into new quasi-equilibria by altering the solar constant by ± 25 Wm−2 and initialize idealized CO2 climate change experiments from these climate states. The simulations branched off from the warm and control states, with increased and unaltered solar constant, respectively, show similar global mean feedback parameters, effective CO2 radiative forcings (ERF) and ocean heat uptake efficiencies and therefore simulate indiscernibly different amounts of global warming. The experiments starting from the cold climate state behave differently: The CO2 ERF is lower mostly because of rapid adjustments in the clouds, and the climate sensitivity is enhanced, mainly due to a large surface albedo feedback caused by the increased sea ice and snow coverage that extends to lower latitudes. The global heat uptake efficiency is reduced in the cold state. While taking up more heat in the Southern Ocean than the experiments from the warmer states much less heat is taken up by the North Atlantic. The less stabilizing net climate feedback parameter and the decreased ocean heat uptake efficiency dominate over the reduced CO2 ERF, and the simulations initialized from the cold state show ~ 10% more global warming compared to those from the control state. This enhanced warming mainly occurs at higher-latitudes over sea ice and snow-covered areas and the North Atlantic. While the local climate response may depend strongly on the base state, the future global mean temperature increase simulated by CESM1 is remarkably independent on the initial climate state. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "57211623938;57195065818;7404732357;7201504886;7003696273;56592876500;25649175400;35775264900;15724418700;","A 1D RCE study of factors affecting the tropical tropopause layer and surface climate",2019,"10.1175/JCLI-D-18-0778.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074668680&doi=10.1175%2fJCLI-D-18-0778.1&partnerID=40&md5=e5c5345c0ed6b60cf6166580a1d86d6c","There are discrepancies between global climate models regarding the evolution of the tropical tropopause layer (TTL) and also whether changes in ozone impact the surface under climate change. We use a 1D clear-sky radiative–convective equilibrium model to determine how a variety of factors can affect the TTL and how they influence surface climate. We develop a new method of convective adjustment, which relaxes the temperature profile toward the moist adiabat and allows for cooling above the level of neutral buoyancy. The TTL temperatures in our model are sensitive to CO2 concentration, ozone profile, the method of convective adjustment, and the upwelling velocity, which is used to calculate a dynamical cooling rate in the stratosphere. Moreover, the temperature response of the TTL to changes in each of the above factors sometimes depends on the others. The surface temperature response to changes in ozone and upwelling at and above the TTL is also strongly amplified by both stratospheric and tropospheric water vapor changes. With all these influencing factors, it is not surprising that global models disagree with regard to TTL structure and evolution and the influence of ozone changes on surface temperatures. On the other hand, the effect of doubling CO2 on the surface, including just radiative, water vapor, and lapse-rate feedbacks, is relatively robust to changes in convection, upwelling, or the applied ozone profile. © 2019 American Meteorological Society." "56120519800;7103016965;6603871013;7006760857;","Verification of a seeder–feeder orographic precipitation enhancement scheme accounting for low-level blocking",2019,"10.1002/qj.3584","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071319686&doi=10.1002%2fqj.3584&partnerID=40&md5=8db57185930013b77861430daf27d94f","A subgrid parametrization scheme representing the enhancement of precipitation due to subgrid orography via the seeder–feeder (SF) effect has been modified to account for flow blocking in small Froude number situations. The scheme was validated in a set of limited-area model simulations with a 1.5 km grid spacing, in which the orography was degraded by varying amounts. For simulations in which the largest orographic scales are still fairly well represented, the SF scheme was able to reduce the precipitation deficit by 30 to 70%. For simulations where the hills were completely subgrid, the SF scheme was still able to reduce the precipitation deficit by 10 to 30%. As well as increasing the integrated precipitation in global simulations with various grid spacings, some of the precipitation production was shifted from the convection scheme, with its very simple microphysical representation, to the microphysics scheme. In a long-duration climate simulation, the SF scheme enhancements of orographic precipitation perturb the large-scale hydrological cycle, as evidenced by the far-field changes in both microphysical and convective precipitation. Changes over major mountain ranges were similar to those described for the case-studies, so long as the upstream precipitation impinging on the mountains was not reduced by these changes in the global hydrological cycle. Increased atmospheric drying reduces column-integrated resolved cloud water mixing ratios over mountains, reducing a positive bias in the amount of optically thick cloud with low- to mid-level tops compared to ISCCP satellite observations. The associated reductions in cloud albedo slightly reduced the RMS error in the top-of-atmosphere outgoing short-wave radiative fluxes over mountains compared to CERES satellite observations. © 2019 Crown copyright. Quarterly Journal of the Royal Meteorological Society © 2019 Royal Meteorological Society" "56557053600;6701363731;54931083200;26434217100;18434033000;6602537415;55915387400;","Direct and semi-direct radiative effect of North African dust in present and future regional climate simulations",2019,"10.1007/s00382-019-04788-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065260643&doi=10.1007%2fs00382-019-04788-z&partnerID=40&md5=09c389f2333d7ad878b466fbec928537","This study explores the direct and semi-direct radiative effect of North African dust in the present and future climate using the regional climate model RegCM4. The simulations cover a historical decade extending from December 1999 to November 2009 and a future decade that spans from December 2089 to November 2099 under the Representative Concentration Pathway 4.5 (RCP4.5), without considering land-cover/land-use changes. For each time-slice a set of two experiments was conducted, namely the “Control”, in which dust is radiatively inactive and the “Feedback”, in which dust interacts with shortwave and longwave radiation. The impact of North African dust on the regional radiative balance is assessed by comparing the “Feedback” and the “Control” experiments during the historical period. The results indicate that the combined effect of dust Direct + Semi-direct Radiative Effect (DSRE) on the shortwave is − 13.8 W m−2 and − 10.7 W m−2 over the Sahel and the Sahara, respectively. The Direct Radiative Effect (DRE) dominates over the Semi-direct Radiative Effect (SRE) in both winter and summer, although during summer over some parts of the desert the SRE in the longwave spectrum accounts for almost 50% of the DSRE. Part of this is due to a noteworthy statistically significant increase of clouds that reaches values up to 3% and stretches across the eastern and western Sahara desert. Dust DSRE intensifies moderately in the future period (− 15.8 W m−2 and − 11.0 W m−2), while its spatial distribution remains the same, suggesting that the effect of climate change in the atmosphere will not alter the radiative effect of dust over North Africa considerably. When taking into account the dust radiative feedback in regional climate simulations the maximum temperature is altered by − 0.2/− 0.2 °C and − 0.3/− 0.6 °C over the Sahel and Sahara regions, respectively, during the summer/winter period, mainly as a result of changes in the shortwave radiative balance. On the contrary, the minimum temperature increases, since it is mostly controlled by the longwave radiation emitted from the Earth’s surface. In the future period the near surface air temperature increases by 1.5–2.5 °C and the fine dust column burden increases by + 4% to + 8% in comparison to the historical period, mainly due to the RCP4.5 forcing. When the dust feedback on climate is active in future simulations it can decrease the summer daily maximum temperature by 0.3 °C over Sahel, and decrease or increase it locally in Sahara by up to 0.2 °C. Prior to the Feedback-Control analysis an extensive evaluation has been conducted for dust optical depth, dust extinction, near surface air temperature and cloud fraction cover using the LIVAS, CRU and CM SAF datasets. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "57210323627;13103142000;55962304900;","Indigenous strategies used by selected farming communities in KwaZulu Natal, South Africa, to manage soil, water, and climate extremes and to make weather predictions",2019,"10.1002/ldr.3395","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070277424&doi=10.1002%2fldr.3395&partnerID=40&md5=9117ddea8a3c46de09297c71c67332fb","Most of rural South Africa is semi arid, experiencing a variable climate with extreme weather events such as droughts and floods. Communal farmers experience problems of getting reliable weather information. Datasets used to describe climate change and variability rely on spatially interpolated gridded data from a few weather stations. The ability of gridded climate data to describe climate variability at the local level has been widely questioned. Communal farmers have developed indigenous strategies to cope with these extremes in order to sustain agricultural production. The objective of this study was to document indigenous strategies that smallholder farmers in Bergville and Msinga, in KwaZulu Natal Province, use to predict weather, conserve soil and water, and manage climate extremes events. Data were gathered through key informant interviews, focus group discussions, and questionnaire. Results showed that more farmers in Msinga than Bergville observed reduced rainfalls and increased temperatures as an indicator of climate variability (p<.05). Bergville and Msinga communal farmers use indigenous indicators such as wind and cloud patterns, animal and bird behaviour, moon shape, and position of the sun to predict weather. Communal farmers using manure were 0.17 times more likely to conserve soil and water when compared with those using artificial fertilizer (p<.05). Thus, indigenous knowledge system (IKS) can be used to conserve soil and water and manage climate extremes and variability. Communal farmers also resist adopting unfamiliar strategies that are forced on them without proper engagement. Communal farmers have managed to survive extreme weather events using IKS. © 2019 John Wiley & Sons, Ltd." "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." "41762693400;","Quantifying the global impact of tropical cyclone-associated gravity waves using HIRDLS, MLS, SABER and IBTrACS data",2019,"10.1002/qj.3602","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070662533&doi=10.1002%2fqj.3602&partnerID=40&md5=aee5108f544f30d8b923365bec4e6cb8","Tropical convective systems are major sources of atmospheric gravity waves (GWs). These waves are a key driver of global atmospheric circulation, especially in the middle and upper atmosphere. Tropical cyclones (TCs) such as hurricanes and typhoons are particularly dramatic examples of such systems, and are therefore potentially significant individual sources of GWs. To investigate this effect, GW observations from three satellite limb sounders in the vicinity of TCs are produced and analysed. By statistically combining 15 years of GW observations from 1,379 individual TCs represented in the International Best Track Archive for Climate Stewardship, it is shown that TCs are associated with a 15% increase of GW amplitudes over background and a 25% increase in measured momentum fluxes, primarily during the period immediately before the TC. It is further shown that this additional contribution is small relative to other GW-generating processes, and thus that individual TCs do not have a large quantitative effect on the dynamics of the middle and upper atmosphere as a whole. Thus, it is concluded that accurate modelling of TC-generated short vertical wavelength GWs need not be a development priority for the next generation of weather and climate models. The results also demonstrate that stronger GW activity is associated with TCs that will later develop into hurricane-intensity storms than is observed for those that will not, and thus that better space-based monitoring of stratospheric GW activity could be a useful tool to help improve the forecasting of strong hurricane events in the presence of obscuring tropospheric cloud. © 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society." "57201492169;57209711809;56871296700;57193451684;6602960153;","Science for everyone (ScifE): A proposed framework for science as a service using interactive web technologies",2019,"10.1016/j.cageo.2019.06.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068501043&doi=10.1016%2fj.cageo.2019.06.001&partnerID=40&md5=7b060609bc15d8d44a4596059b48e9db","Current computing platforms, including HPC, Grid and Cloud computing, offer many computational resources. These platforms can provide the scientific world with on-demand and scalable computing power. However, their use requires advanced computer skills. In our work, we summarize the main problems found by research scientists when they attempt to execute complex software on one or several of these platforms. As a solution to these problems, we propose the Science for Everyone (ScifE) framework, and an intuitive and easy-to-use web interface, to perform scientific experiments on HPC or Cloud platforms. The Community Earth System Model (CESM) has been used to test our proof-of-concept framework as it is a complex scientific software used by many climate researchers. Using our framework, a user can execute CESM with custom parameters with only a few clicks on the web interface. As ScifE is generic, other software can be imported relatively easy to our framework. Additional collaborative tools are being developed for successive versions of ScifE, enhancing the practice of science. © 2019" "56875173300;54682443200;55752524000;6603121976;","Constructing long-term high-frequency time series of global lake and reservoir areas using Landsat imagery",2019,"10.1016/j.rse.2019.111210","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069920213&doi=10.1016%2fj.rse.2019.111210&partnerID=40&md5=e45e95d6a718cbabd3643bf9adf797b6","Improved monitoring of inundation area variations in lakes and reservoirs is crucial for assessing surface water resources in a growing population and a changing climate. Although long-record optical satellites, such as Landsat missions, provide sub-monthly observations at fairly fine spatial resolution, cloud contamination often poses a major challenge for producing temporally continuous time series. We here proposed a novel method to improve the temporal frequency of usable Landsat observations for mapping lakes and reservoirs, by effectively recovering inundation areas from contaminated images. This method automated three primary steps on the cloud-based platform Google Earth Engine. It first leveraged multiple spectral indices to optimize water mapping from archival Landsat images acquired since 1992. Errors induced by minor contaminations were next corrected by the topology of isobaths extracted from nearly cloud-free images. The isobaths were then used to recover water areas under major contaminations through an efficient vector-based interpolation. We validated this method on 428 lakes/reservoirs worldwide that range from ~2 km2 to ~82,000 km2 with time-variable levels measured by satellite altimeters. The recovered water areas show a relative root-mean-squared error of 2.2%, and the errors for over 95% of the lakes/reservoirs below 6.0%. The produced area time series, combining those from cloud-free images and recovered from contaminated images, exhibit strong correlations with altimetry levels (Spearman's rho mostly ~0.8 or larger) and extended the hypsometric (area-level) ranges revealed by cloud-free images alone. The combined time series also improved the monthly coverage by an average of 43%, resulting in a bi-monthly water area record during the satellite altimetry era thus far (1992–2018). The robustness of this method was further verified under five challenging mapping scenarios, including fluvial lakes in humid basins, reservoirs with complex shape geometries, saline lakes with high mineral concentrations, lakes/reservoirs in mountainous regions, and pan-Arctic lakes with frequent snow/ice covers. Given such performance and a generic nature of this method, we foresee its potential applications to assisting water area recovery for other optical and SAR sensors (e.g., Sentinel-2 and SWOT), and to estimating lake/reservoir storage variations in conjunction with altimetry sensors. © 2019 Elsevier Inc." "57188809664;56284582200;7005446873;","A simple ensemble approach for more robust process-based sensitivity analysis of case studies in convection-permitting models",2019,"10.1002/qj.3606","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071284899&doi=10.1002%2fqj.3606&partnerID=40&md5=c4e436f95dfcf7640ac3b3b5f675d6ea","Case studies remain an important method for meteorological parameter sensitivity process studies. However, these types of study often use just a few case studies (typically up to three) and are not tested for statistical significance. This approach can be problematic at the convective scales, since uncertainty in the representation of an event increases, and the variability in the atmosphere arising from convective-scale noise is not routinely taken into account. Here we propose a simple ensemble method for performing more robust sensitivity analysis without the need for an operational-style ensemble prediction system and demonstrate it using a case study from the 2005 Convective Storm Initiation Project. Boundary-layer stochastic potential temperature perturbations with Gaussian spatial structure are used to create small ensembles to examine the impact of increasing cloud droplet number concentration (CDNC) on precipitation. Whilst there is a systematic difference between the experiments, such that increasing the CDNC reduces the precipitation, there is also an overlap between the different ensembles implying that convective-scale variability should be taken into account in case study process-based sensitivity studies. © 2019 Royal Meteorological Society" "54408382600;55684453700;","Satellite-based estimation of the aerosol forcing contribution to the global land surface temperature in the recent decade",2019,"10.1016/j.rse.2019.111299","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068444356&doi=10.1016%2fj.rse.2019.111299&partnerID=40&md5=abf914ee2b1013a711682ffb3686b2dd","The aerosol forcing is an essential factor of global climate change, which can be estimated by various models. However, the model results ranging from −2.8 to 2.2 K remain controversial because of unavoidable uncertainty, leaving a great gap for global change prediction. This study aims to evaluate the forcing on the land surface temperature (Ts) using satellite-based observations. Based on the Blackbody radiation and surface radiation budget, first, a semi-physical framework is developed to estimate the Ts. Subsequently, the aerosol forcing is calculated by measuring the Ts difference between the changing aerosol scenario and baseline scenario with a fixed aerosol amount. Results show that the framework simulates Ts with acceptable accuracy (R = 0.62 and RMSE = 1.48 K), which supports the estimation of aerosol forcing. Generally, the change in the aerosol contributes 0.005 ± 0.237 K to the global Ts, which presents significant temporal and spatial variabilities. Temporally, the forcing shows a decreasing trend of −0.0006 K/year (R2 = 0.29, p = 0.031). Spatially, the forcing tends to warm the surface in regions with arid climate, low-cloud fraction, and moderate vapor or in sparsely vegetated and cool regions because of the potential interactions with climatic and environmental factors. The result of this study helps to reduce the uncertainty and validate the model results, which further supports the research on global climatic and environmental change. © 2019 Elsevier Inc." "14420580800;57208344447;57217502021;55536426000;55694096400;7201808027;7006857631;7801679641;15846932500;56432110300;","Cryptic diversity and ranavirus infection of a critically endangered Neotropical frog before and after population collapse",2019,"10.1111/acv.12498","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064574270&doi=10.1111%2facv.12498&partnerID=40&md5=ebdc32df244fde23ac138bdae8b61594","Mesoamerican amphibian declines in apparently pristine and protected habitats have been severe, especially at elevations above 500 m sea level and have been linked to emerging diseases and a changing climate. The Craugastor punctariolus species series of direct developing frogs is endemic to the region and used to be comprised of 33 species, seven of which have known populations at present. One of these, C. ranoides, endemic to southern Nicaragua and Costa Rica, was historically found in cloud forest sites of Área de Conservación Guanacaste (ACG) in north-west Costa Rica and extended into dry forest sites 20 km distant. Here, C. ranoides declined and disappeared from high elevation sites between the mid-1980s and early 1990s, but populations persisted in the lowland dry forest. We compared the genetic richness and ranavirus infection status of C. ranoides from extant dry forest populations to historic museum specimens of now extinct ACG cloud forest populations using DNA sequence diversity at two mitochondrial loci and molecular screening for ranavirus. Extant dry forest populations of C. ranoides formed a monophyletic group which included historic specimens sampled at cloud forest sites. However, the extirpated ACG cloud forest population contained additional diversity: samples formed a divergent clade with unknown spatial distribution. Ranavirus was detected in both current and museum samples of C. ranoides and sequences from a 267-nucleotide region of the major capsid protein gene shared 100% sequence identity with one another and with Frog virus 3. Our findings document cryptic diversity within an endangered species that has demonstrated no recovery in cloud forests and raises questions about Ranavirus and its potential link to the amphibian declines in this system. The presence of the same C. ranoides clade within present day and historical samples suggests a potential for effective translocation and repopulation of extirpated cloud forest populations. © 2019 The Zoological Society of London" "57196198872;57195530363;34881956500;57201646570;7202856872;","Assessing the pasturelands and livestock dynamics in Brazil, from 1985 to 2017: A novel approach based on high spatial resolution imagery and Google Earth Engine cloud computing",2019,"10.1016/j.rse.2019.111301","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068378546&doi=10.1016%2fj.rse.2019.111301&partnerID=40&md5=3987b46699dd85689966246971c915e1","The livestock activity accounts for a large part of the transformations in land cover in the world, with pasture areas being the main land use in Brazil and the main livelihood of the largest commercial herd in the world. In this sense, a better understanding of the spatial-temporal dynamics of pasture areas is of fundamental importance for a better occupation and territorial governance. Moreover, because they provide different ecosystem services, pastures play a key role in mitigating climate change and in meeting GHG emission reduction targets. Within this context, and based on Landsat image processing via machine learning methods in a cloud computing platform (Google Earth Engine), this work has mapped, annually and in an unprecedented way, the totality of the Brazilian pastures, from 1985 to 2017. With an overall accuracy of about 90%, the 33 maps produced indicated the pasture area varying from ~118 Mha ±3.41% (1985) to ~178 Mha ±2.53% (2017), with this expansion occurring mostly in the northern region of the country and to a lesser extent in the midwest. Temporarily, most of this expansion occurred in the first half of the period evaluated (i.e. between 1985 and 2002), with an increase in Brazilian pasture areas of ~57 mha in just 17 years. After 2002, this area remained relatively stable, varying between ~175 mha ±2.48% and ~178 mha ±2.53% by 2017. In 33 years, about 87% of the mapped areas experienced zero, one, two, or three land-cover / land-use transitions; overall, of the ~178 mha ±2.53% of existing pastures in 2017, ~52 mha are at least 33 years old, ~66 mha were formed after 1985, and ~33 mha may have undergone some reform action in the period under consideration. The dynamics revealed in this study reinforce the thesis of pasture utilization as a land reserve, and demonstrate the importance of these areas in the economic, social, and environmental aspects of Brazil. © 2019 Elsevier Inc." "55947922300;7103180783;","Projected near-term changes in three types of heat waves over China under RCP4.5",2019,"10.1007/s00382-019-04743-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064446559&doi=10.1007%2fs00382-019-04743-y&partnerID=40&md5=ed16c01001b4666aae49e55ff1158dc4","The changes in three aspects of frequency, intensity and duration of the compound, daytime and nighttime heat waves (HWs) over China during extended summer (May–September) in a future period of the mid-21st century (FP; 2045–2055) under RCP4.5 scenario relative to present day (PD; 1994–2011) are investigated by two models, MetUM-GOML1 and MetUM-GOML2, which comprise the atmospheric components of two state-of-the-art climate models coupled to a multi-level mixed-layer ocean model. The results show that in the mid-21st century all three types of HWs in China will occur more frequently with strengthened intensity and elongated duration relative to the PD. The compound HWs will change most dramatically, with the frequency in the FP being 4–5 times that in the PD, and the intensity and duration doubling those in the PD. The changes in daytime and nighttime HWs are also remarkable, with the changes of nighttime HWs larger than those of daytime HWs. The future changes of the three types of HWs in China in two models are similar in terms of spatial patterns and area-averaged quantities, indicating these projected changes of HWs over the China under RCP4.5 scenario are robust. Further analyses suggest that projected future changes in HWs over China are determined mainly by the increase in seasonal mean surface air temperatures with change in temperature variability playing a minor role. The seasonal mean temperature increase is due to the increase in surface downward longwave radiation and surface shortwave radiation. The increase in downward longwave radiation results from the enhanced greenhouse effect and increased water vapour in the atmosphere. The increase in surface shortwave radiation is the result of the decreased aerosol emissions, via direct aerosol–radiation interaction and indirect aerosol–cloud interaction over southeastern and northeastern China, and the reduced cloud cover related to a decrease in relative humidity. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "7006292262;7201788967;","Asteroid impact effects on Snowball Earth",2019,"10.1111/maps.13294","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067359015&doi=10.1111%2fmaps.13294&partnerID=40&md5=df49afaf91c7697cc45c66594b4aebd7","Several Snowball Earth periods, in which the Earth has been (almost) totally glaciated, are known from Earth history. Neither the trigger for the initiation, nor the reason for the ending of such phases, are well understood. Here we discuss some mechanical effects of the impact of asteroids 5–10 km in diameter on the Snowball Earth environment. An impact of this scale is the largest impact that is statistically predictable for 10–60 Myr time periods. The impact cratering itself (shock waves, impact crater formation) is not powerful enough to change the natural climate evolution path on Earth. However, the products of impact (mainly—water vapor) can be quickly distributed over a substantial part of the globe, influencing the global circulation (e.g., facilitating cloud formation). It is a question for future studies to confirm if such an event (which is possible statistically during this interval) may or may not have influenced the global climate of the Snowball Earth, and/or contributed to deglaciation. © 2019 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals, Inc. on behalf of The Meteoritical Society (MET)" "57208795965;57201809767;55626987300;57191221261;","A two-stage fusion framework to generate a spatio'temporally continuous MODIS NDSI product over the Tibetan Plateau",2019,"10.3390/rs11192261","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073457166&doi=10.3390%2frs11192261&partnerID=40&md5=eeae25256168d1fd82ef67fe7a9fd7ac","The Tibetan Plateau (TP) is an important component of the global environmental system, on which the snow cover greatly affects the regional climate and ecology. Moderate resolution imaging spectroradiometer (MODIS) snow cover products have been demonstrated to be appropriate for investigating the snow cover over the TP. However, they are subject to cloud obscuration, and the TP's extremely complex terrain makes the snow monitoring difficult. Therefore, in this paper, we propose a two-stage spatio'temporal fusion framework for the cloud removal of MODIS C6 snow products, including an adjusted Terra and Aqua combination (TAC) and a spatio'temporal fusion based on Gaussian kernel function and error correction (STF-GKF-EC). To the best of our knowledge, this is the first time that a spatio'temporally continuous daily 500-m MODIS normalized difference snow index (NDSI) product has been generated for the TP, which greatly improves the spatial and temporal resolutions of the current snow cover products. The main stage, STF-GKF-EC, adaptively weights the spatial and temporal correlations by the Gaussian kernel function, and further takes the rapid changes of snow cover into consideration through the error correction. The experiments indicated that STF-GKF-EC removes clouds completely, achieving an overall accuracy (OA) and mean absolute error (MAE) of 91.48% and 3.88, respectively. Based on the cloud-removed results, during 2001'2017, as far as the intra-annual variation is concerned, a large proportion of the snow cover appears between October and May, with a peak in February/March, and the variation is mainly controlled by temperature. For the inter-annual variation, an obvious increasing trend of 0.68/year for NDSI is observed before 2005, followed by a slight decreasing trend of 0.16/year, in which precipitation is a better explanation factor than temperature. © 2019 by the authors." "57200857362;7004563395;55962154500;56583139400;8284949000;56504563100;57094306300;","Estimating hourly land surface downward shortwave and photosynthetically active radiation from DSCOVR/EPIC observations",2019,"10.1016/j.rse.2019.111320","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070096051&doi=10.1016%2fj.rse.2019.111320&partnerID=40&md5=ef400efde61bc47f1b801f788a947135","The direct and diffuse components of downward shortwave radiation (SW), and photosynthetically active radiation (PAR) at the Earth surface play an essential role in biochemical (e.g. photosynthesis) and physical (e.g. energy balance) processes that control weather and climate conditions, and many ecological processes. Space-based observations have the unique advantage of providing reliable estimates of SW and PAR globally with sufficient accuracy for constructing Earth's radiation budget and estimating land-surface fluxes that control these processes. However, most existing space-based SW and PAR estimations from sensors onboard polar-orbiting and geostationary satellites have inherently low temporal resolution and/or limited spatial coverage of the entire Earth surface. The unique location/orbit of Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) provides an unprecedented opportunity to obtain global estimates of SW and PAR accurately at a high temporal resolution of about 1–2 h. In this study, we developed and used a model (random forest, RF) to estimate global hourly SW and PAR at 0.1° × 0.1° (about 10 km at equator) spatial resolution based on EPIC measurements. We used a combination of EPIC Level-2 products, including solar zenith angle, aerosol optical depth, cloud optical thickness, cloud fraction, total column ozone and surface pressure with their associated quality flags to drive the RF model for estimating SW and PAR. We evaluated the model results against in situ observations from the Baseline Surface Radiation Network (BSRN) and Surface Radiation Budget Network (SURFRAD). We found the EPIC SW and PAR estimates at both hourly and daily time scales to be highly correlated and consistent with these independently obtained in situ measurements. The RMSEs for estimated daily diffuse SW, direct SW, total SW, and total PAR were 19.10, 38.47, 33.52, and 14.09 W/m2, respectively, and the biases for these estimates were 1.71, −0.77, 1.04 and 4.11 W/m2, respectively. We further compared the estimated SW and PAR with the Clouds and the Earth's Radiant Energy System Synoptic 1° × 1° (CERES SYN1deg) products and found a good correlation and consistency in their accuracy, spatial patterns and latitudinal gradient. The EPIC SW and PAR estimates provide a unique dataset (i.e. observations from single instrument from pole-to-pole for the entire sunlit portion of Earth) for characterizing their diurnal cycles and their potential impact on photosynthesis and evapotranspiration processes. © 2019 Elsevier Inc." "8408994300;56161114300;7003780337;14028257300;56041136700;7102860121;7102144083;6506948406;6603126554;6701549552;57202112487;7006417494;","Benefits of a closely-spaced satellite constellation of atmospheric polarimetric radio occultation measurements",2019,"10.3390/rs11202399","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074206949&doi=10.3390%2frs11202399&partnerID=40&md5=c8395fc7c5f4a9978c8356ef4c9d60a4","The climate and weather forecast predictive capability for precipitation intensity is limited by gaps in the understanding of basic cloud-convective processes. Currently, a better understanding of the cloud-convective process lacks observational constraints, due to the difficulty in obtaining accurate, vertically resolved pressure, temperature, and water vapor structure inside and near convective clouds. This manuscript describes the potential advantages of collecting sequential radio occultation (RO) observations from a constellation of closely spaced low Earth-orbiting satellites. In this configuration, the RO tangent points tend to cluster together, such that successive RO ray paths are sampling independent air mass quantities as the ray paths lie ""parallel"" to one another. When the RO train orbits near a region of precipitation, there is a probability that one or more of the RO ray paths will intersect the region of heavy precipitation, and one or more would lie outside. The presence of heavy precipitation can be discerned by the use of the polarimetric RO (PRO) technique recently demonstrated by the Radio Occultations through Heavy Precipitation (ROHP) receiver onboard the Spanish PAZ spacecraft. This sampling strategy provides unique, near-simultaneous observations of the water vapor profile inside and in the environment surrounding heavy precipitation, which are not possible from current RO data. © 2019 by the authors." "57212212049;6507238098;57212215506;57204934886;6602976773;6602159587;57202941954;24831940900;57204547799;","Assessing CERES Surface Radiation Components for Tropical and Subtropical Biomes",2019,"10.1109/JSTARS.2019.2939382","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076217941&doi=10.1109%2fJSTARS.2019.2939382&partnerID=40&md5=6deee741a58b2135949c7a7476e8db2e","An adequate estimate of the radiation components on the earth's surface may help reveal many important interactions between the earth's surface and the atmosphere. In-situ measurements of radiation components are sparse, and remote sensing is one way to overcome this limitation. The clouds and the earth's radiant energy system (CERES) provides a long-term estimate of shortwave and longwave radiation over the entire globe. This article compared and evaluated all components of the surface radiation, estimated using CERES SYN1deg Ed3A and SYN1deg Ed4A data (shortwave up and down, longwave up and down, and photosynthetically active radiation) against measurements for 15 sites located in Brazil. Our results indicated that CERES SYN1deg estimates are accurate for all variables evaluated, with the SYN1deg Ed4A version increasing the $R^{2}$ and decreasing the RMSE from the SYN1deg Ed3A version. We also evaluated the main driving factors controlling the variability of the surface radiation components, using cluster analysis and multiple linear regression. The results showed that surface temperature and total precipitable water vapor are the main driving factors affecting the variability of the different radiation components. The results also highlighted the influence of climate conditions and biome features on the estimates of surface radiation components by CERES. The radiation data provided by CERES SYN1deg Ed4A proved to be a promising alternative for large regions where meteorological information is unavailable or sparse. © 2008-2012 IEEE." "57203441361;8986276700;54890047800;6602955096;25936649000;35265615300;7006783395;","Characterization of carbonaceous aerosols in Asian outflow in the spring of 2015: Importance of non-fossil fuel sources",2019,"10.1016/j.atmosenv.2019.116858","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070663297&doi=10.1016%2fj.atmosenv.2019.116858&partnerID=40&md5=f565fc9e2aeb7d8d0466a58f8ca886f5","The sources of elemental (EC) and organic carbon (OC) aerosols in Asian outflow were investigated in the spring of 2015 in terms of radiocarbon (14C) and molecular marker analyses. The contribution of fossil fuel (FF) sources to carbonaceous aerosols (TC) significantly increased in polluted air masses with enhancements in the concentrations of carbon monoxide. For EC, FF sources dominated in the polluted air masses. For OC, the contributions of non-FF sources other than biomass burning (BB) were found to be significant (comparable to or higher than those of FF sources), especially in air masses with higher values of the water-soluble fraction of OC (fWSOC) and 14C concentrations (F14C). Positive correlations between fWSOC and F14C indicate that the origins of TC (mainly OC) have great impacts on the water solubility variability and the subsequent cloud formation processes of OC during transport. We found the importance of natural sources as possible origins of OC in non-polluted (i.e., background) air. This study raises the need to further investigate the source apportionment of OC, especially its natural origins, for more accurately assessing the climatic impacts of EC and OC in East Asia. © 2019 Elsevier Ltd" "24168479200;57209469051;57209478230;35206916200;57209477060;57209467963;","Linkages between mid-latitude cirrus cloud properties and large-scale meteorology at the SACOL site",2019,"10.1007/s00382-019-04843-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067872139&doi=10.1007%2fs00382-019-04843-9&partnerID=40&md5=a235a46d7434b0491a848bcd23216262","The linkages between midlatitude cirrus properties and large-scale meteorology are investigated in this study by using 2-year observations from a ground Ka-band Zenith Radar (KAZR) and the Earth’s Radiant Energy System (CERES) SYN1deg satellite product over the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). Four atmospheric parameters (i.e. upward motion, relative humidity, stability and temperature at upper atmosphere) are used to examine the cirrus dependence on these factors. It is found that cirrus properties significantly depend on the changes of the four parameters and are most linearly correlated with upper atmosphere temperature. Cirrus infrared (IR) emissivity and ice water path (IWP) are sensitive to the strength of upward motions (ω), while cirrus thickness and albedo are more sensitive to relative humidity. An Empirical Orthogonal Function (EOF) is used to combine the four meteorological factors into a single variable and isolate the irrelevant synoptic noise to cirrus development and dissipation from the structure strongly associated with cirrus variations. The first leading principle component (PC1) is much better correlated with cirrus properties than any one of the four parameters. We further apply the EOF analysis to all 37 vertical levels of the four parameters. It is found that a negative area of the main structure between 6 and 10 km above ground level (AGL) is well collocated with the cirrus distribution from the KAZR observations on a diurnal time scale, indicating a robust relationship between cirrus and the combined meteorological fields. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature." "57188814286;26644101800;36350395000;57211324940;55608513400;","Long-term changes of open-surfacewater bodies in the Yangtze River Basin based on the google earth engine cloud platform",2019,"10.3390/rs11192213","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073417899&doi=10.3390%2frs11192213&partnerID=40&md5=9d87c96c4a95f12c59e460589c6064a2","The spatiotemporal changes of open-surface water bodies in the Yangtze River Basin (YRB) have profound influences on sustainable economic development, and are also closely relevant to water scarcity in China. However, long-term changes of open-surface water bodies in the YRB have remained poorly characterized. Taking advantage of the Google Earth Engine (GEE) cloud platform, this study processed 75,593 scenes of Landsat images to investigate the long-term changes of open-surface water bodies in the YRB from 1984 to 2018. In this study, we adopted the percentile-based image composite method to collect training samples and proposed a multiple index water detection rule (MIWDR) to quickly extract the open-surface water bodies. The results indicated that (1) the MIWDR is suitable for the long-term and large-scale Landsat water bodies mapping, especially in the urban regions. (2) The areas of permanent water bodies and seasonal water bodies were 29,076.70 km2 and 21,526.24 km2, accounting for 57.46% and 42.54% of the total open-surface water bodies in the YRB, respectively. (3) The permanent water bodies in the YRB increased along with the decreases in the seasonal water bodies from 1984 to 2018. In general, the total open-surface surface water bodies in the YRB experienced an increasing trend, with an obvious spatial heterogeneity. (4) The changes of open-surface water bodies were associated with the climate changes and intense human activities in the YRB, however, the influences varied among different regions and need to be further investigated in the future. © 2019 by the authors." "57192592299;55364216300;16418092800;","Evaluation of Hybrid Polarimetric Decomposition Techniques for Forest Biomass Estimation",2019,"10.1109/JSTARS.2019.2947088","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076152583&doi=10.1109%2fJSTARS.2019.2947088&partnerID=40&md5=3d59fc9851f8f85e1c687440d37c352c","Forest plays an important role in carbon sequestration and biosphere-atmosphere interaction. Knowledge of forest biomass content helps in assessing its sustainability and thus mitigating climate change. The advancement in remote sensing technology provides the capability of estimating biomass at a large scale. Hybrid polarimetry has gained significant attention among other radar missions due to its fundamental advantages. In this article, the potential of hybrid polarimetric SAR is evaluated for the efficient forest aboveground biomass (AGB) estimation for Barkot Forest, Uttarakhand, India. Forest biomass is calculated by means of the extended water cloud model. Scattering parameters are derived using two widely used hybrid polarimetric decomposition techniques, m-δ and m-χ decompositions. Potential insight into the efficacy of these decomposition techniques toward biomass estimation is brought forth. The modeled AGB estimates were compared with fully polarimetric data-based estimated AGB. The estimation based on the m-χ and m-δ decomposition resulted in biomass estimation with an accuracy of 75.8% and 73.4%, respectively. © 2008-2012 IEEE." "57194527119;6602809597;55893826700;7102953444;","The annual cycle of fractional atmospheric shortwave absorption in observations and models: Spatial structure, magnitude, and timing",2019,"10.1175/JCLI-D-19-0212.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074632310&doi=10.1175%2fJCLI-D-19-0212.1&partnerID=40&md5=6cc55431bc201436fcbeb2637232b709","We use the best currently available in situ and satellite-derived surface and top-of-the-atmosphere (TOA) shortwave radiation observations to explore climatological annual cycles of fractional (i.e., normalized by incoming radiation at the TOA) atmospheric shortwave absorption ã on a global scale. The analysis reveals that ã is a rather regional feature where the reported nonexisting ã in Europe is an exception rather than the rule. In several regions, large and distinctively different ã are apparent. The magnitudes of ã reach values up to 10% in some regions, which is substantial given that the long-term global mean atmospheric shortwave absorption is roughly 23%. Water vapor and aerosols are identified as major drivers for ã while clouds seem to play only a minor role for ã. Regions with large annual cycles in aerosol emissions from biomass burning also show the largest ã. As biomass burning is generally related to human activities, ã is likely also anthropogenically intensified or forced in the respective regions. We also test if climate models are able to simulate the observed pattern of ã. In regions where ã is driven by the annual cycle of natural aerosols or water vapor, the models perform well. In regions with large ã induced by biomass-burning aerosols, the models’ performance is very limited. © 2019 American Meteorological Society." "56425375100;9841782300;40660946400;56425599300;7003995572;57209021336;","Leveraging open source software and parallel computing for model predictive control of urban drainage systems using EPA-SWMM5",2019,"10.1016/j.envsoft.2019.07.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070299563&doi=10.1016%2fj.envsoft.2019.07.009&partnerID=40&md5=d89fd4a447d0463c9697119aa963c673","Active stormwater control will play an increasingly important role in mitigating urban flooding, which is becoming more common with climate change and sea level rise. In this paper we describe and demonstrate swmm_mpc, software developed for simulating model predictive control (MPC) for urban drainage systems using open source software (Python and the EPA Stormwater Management Model version 5 (SWMM5)). Swmm_mpc uses an evolutionary algorithm as an optimizer and supports parallel processing. In the demonstration case for a hypothetical, tidally-influenced urban drainage system, the swmm_mpc control policies for two storage units achieved its objectives of 1) practically eliminating flooding and 2) maintaining the water level at the storage units close to a target level. Although the current swmm_mpc workflow was feasible for a simple model using a desktop PC, a high-performance computer or cloud-based computer with more computational cores would likely be needed for most real-world models. © 2019 Elsevier Ltd" "57211626215;55656261100;","Weather prediction using multiple iot based wireless sensors",2019,"10.35940/ijeat.A1037.109119","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074635914&doi=10.35940%2fijeat.A1037.109119&partnerID=40&md5=523e63d48b771e044c296f41f27b8720","Environmental monitoring has become extremely important due to recent changes in the climate. It is important for ensuring a safe and wealthy life of both humans and artifacts. This field is based on remote sensing and wireless sensor networks for gathering data about the environment. Recent advancements, for example, the vision of the Internet of Things (IoT), the distributed computing model, and digital physical frameworks support the transmission and management of huge amounts of data relating to the trends determined in environmental parameters. In this context, the paper presents three different IoT-based wireless sensors for weather prediction and environmental monitoring: one employing User Datagram Protocol (UDP)-based Wi-Fi communication, second communicating through Wi-Fi and Hypertext Transfer Protocol (HTTP), and a third one using Bluetooth communication. The system consists of three different wireless sensor nodes based on Node-MCU Wi-Fi module or Arduino microcontroller that is connected to the internet, and a firebase cloud server, which provides information storage and delivery to remote clients. In addition, to view the result output in an effective and user friendly manner, MIT App Inventor is used to develop applications for Android phones using a web browser and either an associated phone or the on-screen phone person. The system conducts a lookup table which contains the value of temperature, humidity, real time rain, and a level of carbon monoxide (CO) and are used to predict the current environmental conditions. © BEIESP." "57202283678;40661126400;18434901100;6507919264;","Volume loss of the Greenland ice sheet revealed by SARAL/AltiKa repeat passes radar altimetry",2019,"10.1007/s12040-019-1209-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068768517&doi=10.1007%2fs12040-019-1209-3&partnerID=40&md5=f5a3672de737e1c2fc6c589bd51ee68d","The Greenland ice sheet (GrIS) is one of the drivers of global sea level rise and plays a crucial role in understanding the global climate changes. Here, we have estimated and analysed the decadal (between 2013–2016 and 2003–2005) and annual (2014–2015, 2015–2016) volume discharge of ice from the entire GrIS. The 40 Hz Geophysical Data Record product of the unique Ka band (AltiKa) radar altimeter were utilised to derive the elevation, elevation changes and volume changes over the GrIS. To test the first-level accuracy of the result, AltiKa and NASA’s ice, cloud and land elevation satellite digital elevation model (ICESat DEM)-derived elevation were compared, which yielded a correlation value of 0.95. Thereafter, decadal volume changes obtained over the entire GrIS, from the differencing of the AltiKa and ICESat DEM elevation revealed a decreasing rate of 247 km3/year. Moreover, basin-wise analysis indicated the maximum decrease in elevation of basin located in the north and north-west region of GrIS. Annual changes obtained by differencing the AltiKa cycle of the same month (so that the surface condition will remain same) between the two consecutive years, specifically during 2014–2015 and 2015–2016 over the entire GrIS contributed volume loss of 187 and 210 km3, respectively, indicating an enhanced decrease for a later period. © 2019, Indian Academy of Sciences." "55206283600;7401900092;56410306300;56471020600;","Decadal SST variability in the southeast indian ocean and its impact on regional climate",2019,"10.1175/JCLI-D-19-0180.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074942620&doi=10.1175%2fJCLI-D-19-0180.1&partnerID=40&md5=e44f0b626fca99a8e4035fe627689212","The southeast Indian Ocean (SEIO) exhibits decadal variability in sea surface temperature (SST) with amplitudes of;0.2-0.3Kand covaries with the central Pacific (r520.63 with Niño-4 index for 1975-2010). In this study, the generation mechanisms of decadal SST variability are explored using an ocean general circulation model (OGCM), and its impact on atmosphere is evaluated using an atmospheric general circulation model (AGCM). OGCM experiments reveal that Pacific forcing through the Indonesian Throughflow explains,20% of the total SST variability, and the contribution of local wind stress is also small. These windforced anomalies mainly occur near the Western Australian coast. The majority of SST variability is attributed to surface heat fluxes. The reduced upward turbulent heat flux (QT; latent plus sensible heat flux), owing to decreased wind speed and anomalous warm, moist air advection, is essential for the growth of warm SST anomalies (SSTAs). The warming causes reduction of low cloud cover that increases surface shortwave radiation (SWR) and further promotes the warming. However, the resultant high SST, along with the increased wind speed in the offshore area, enhances the upwardQT and begins to cool the ocean. Warm SSTAs co-occur with cyclonic low-level wind anomalies in the SEIO and enhanced rainfall over Indonesia and northwest Australia. AGCM experiments suggest that although the tropical Pacific SST has strong effects on the SEIO region through atmospheric teleconnection, the cyclonic winds and increased rainfall are mainly caused by the SEIO warming through local air-sea interactions. © 2019 American Meteorological Society." "14020621600;57205679744;7102582171;","Large-scale climatic factors driving glacier recession in the Greater Caucasus, 20th–21st century",2019,"10.1002/joc.6101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067463935&doi=10.1002%2fjoc.6101&partnerID=40&md5=2ea61c2106599061dfa6c90f0faf3a96","Over the past 30 years, there has been a catastrophic reduction of the glacierized area in the mountains of the Greater Caucasus, with the values reaching 0.69% per year. Physical mechanisms accountable for such intense melting are investigated in this study. The main trends in the temperature-moisture regime of the Caucasus and adjacent areas for the period 1982–2015 were recovered based on instrumental data and the ERA-Interim data reanalysis. It is demonstrated that there is statistically significant warming for the summer season in the region as a whole. No statistically significant changes were detected in the precipitation regime, despite the increase in the integral moisture content of the atmosphere and in the potential convective energy. The integral moisture content growth is compensated by the increase in the moisture divergence. This happens due to the intensification of large-scale descending atmospheric motions. As a result, the seasonal and annual precipitation amounts do not change significantly. Such effects are possibly the consequence of the global process of “widening of the tropics.” This process is most clearly manifested in the expansion of the Hadley cell and the northward shift of its descending branch. This process can lead to an increased frequency of anticyclones over the southern regions of Europe during the warm part of the year. This, in turn, leads to a negative cloud cover trend as well as an increase in the closely related radiation balance. Apparently, this process is the cause of the intensive reduction of the glaciation area in the North Caucasus. © 2019 Royal Meteorological Society" "56019121300;7403557805;8977584600;8528600400;","Identifying Subsurface Drainage using Satellite Big Data and Machine Learning via Google Earth Engine",2019,"10.1029/2019WR024892","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074301469&doi=10.1029%2f2019WR024892&partnerID=40&md5=36ec45796397c2e71b00e3365abaa96a","Human-induced landscape changes affect hydrologic responses (e.g., floods) that can be detected from a suite of satellite and model data sets. Tapping these vast data sets using machine learning algorithms can produce critically important and accurate insights. In the Red River of the North Basin in the United States, agricultural subsurface drainage (SD; so-called tile drainage) systems have greatly increased since the late 1990s. Over this period, river flow in the Red River has markedly increased and 6 of 13 major floods during the past century have occurred in the past two decades. The impact of SD systems on river flow is elusive because there are surprisingly few SD records in the United States. In this study, Random Forest machine learning (RFML) classification method running on Google Earth Engine's cloud computing platform was able to capture SD within a field (30 m) and its expansion over time for a large watershed (>100,000 km2). The resulting RFML classifier drew from operational multiple satellites and model data sets (total 14 variables with 36 layers including vegetation, land cover, soil properties, and climate variables). The classifier identified soil properties and land surface temperature to be the strongest predictors of SD. The maps agreed well with SD permit records (overall accuracies of 76.9–87.0%) and corresponded with subwatershed-level statistics (r = 0.77–0.96). It is expected that the maps produced with this data-intensive machine learning approach will help water resource managers to assess the hydrological impact from SD expansion and improve flood predictions in SD-dominated regions. ©2019. American Geophysical Union. All Rights Reserved." "56093569100;57206228695;16177404800;56500820900;57209176816;57213397886;","Microwave land emissivity calculations over the Qinghai-Tibetan plateau using FY-3B/MWRI measurements",2019,"10.3390/rs11192206","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073412639&doi=10.3390%2frs11192206&partnerID=40&md5=f27a555ed9b3ee21492d89cc98ac7e80","The Qinghai-Tibetan plateau plays an important role in climate change with its unique characteristics, and the surface emissivity is an important parameter to describe the surface characteristics. It is also very important for the accurate retrieval of surface and atmospheric parameters. Different types of surface features have their own radiation characteristics due to their differences in structure, water content and roughness. In this study, the microwave land surface emissivity (10.65, 18.7, 23.8, 36.5 and 89 GHz) of the Qinghai-Tibetan Plateau was calculated using the simplified microwave radiation transmission equation under clear atmospheric conditions based on Level 1 brightness temperatures from the Microwave Radiation Imager onboard the FY-3B meteorological satellite (FY-3B/MWRI) and the National Centers for Environmental Prediction Final (NCEP-FNL) Global Operational Analysis dataset. Furthermore, according to the IGBP (International Geosphere-Biosphere Program) classified data, the spectrum and spatial distribution characteristics of microwave surface emittance in Qinghai-Tibetan plateau were further analyzed. The results show that almost all 16 types of emissivity from IGBP at dual-polarization (vertical and horizontal) increase with the increase of frequency. The spatial distribution of the retrieving results is in line with the changes of surface cover types on the Qinghai-Tibetan plateau, showing the distribution characteristics of large polarization difference of surface emissivity in the northwest and small polarization difference in the southeast, and diverse vegetation can be clearly seen in the retrieving results. In addition, the emissivity is closely related to the type of land surface. Since the emissivity of vegetation is higher than that of bare soil, the contribution of bare soil increases and the surface emissivity decreases as the density of vegetation decreases. Finally, the source of retrieval error was analyzed. The errors in calculating the surface emissivity might mainly come from spatiotemporal collocation of reanalysis data with satellite measurements, the quality of these auxiliary datasets and cloud and precipitation pixel discrimination scheme. Further quantitative analysis of these errors is required, and even standard procedures may need to be improved as well to improve the accuracy of the calculation. © 2019 by the authors." "56189450300;23970165000;57202625399;6602126569;6602926234;7005018006;35517567400;","Sensitivity of L-band vegetation optical depth to carbon stocks in tropical forests: a comparison to higher frequencies and optical indices",2019,"10.1016/j.rse.2019.111303","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069945284&doi=10.1016%2fj.rse.2019.111303&partnerID=40&md5=3984128e3781fa6e4358289b9169a029","Monitoring vegetation carbon in tropical regions is essential to the global carbon assessment and to evaluate the actions oriented to the reduction of forest degradation. Mainly, satellite optical vegetation indices and LiDAR data have been used to this purpose. These two techniques are limited by cloud cover and are sensitive only to the top of vegetation. In addition, the vegetation attenuation to the soil microwave emission, represented by the vegetation optical depth (VOD), has been applied for biomass estimation using frequencies ranging from 4 to 30 GHz (C- to K-bands). Atmosphere is transparent to microwaves and their sensitivity to canopy layers depends on the frequency, with lower frequencies having greater penetration depths. In this regard, L-band VOD (1.4 GHz) is expected to enhance the ability to estimate carbon stocks. This study compares the sensitivity of different VOD products (from L, C, and X-bands) and an optical vegetation index (EVI) to the above-ground carbon density (ACD). It quantifies the contribution of ACD and forest cover proportion to the VOD/EVI signals. The study is conducted in Peru, southern Colombia and Panama, where ACD maps have been derived from airborne LiDAR. Results confirm the enhanced sensitivity of L-band VOD to ACD when compared to higher frequency bands, and show that the sensitivity of all VOD bands decreases in the densest forests. ACD explains 34% and forest cover 30% of L-band VOD variance, and these proportions gradually decrease for EVI, C-, and X-band VOD, respectively. Results are consistent through different categories of altitude and carbon density. This pattern is found in most of the studied regions and in flooded forests. Results also show that C-, X-band VOD and EVI provide complementary information to L-band VOD, especially in flooded forests and in mountains, indicating that synergistic approaches could lead to improved retrievals in these regions. Although the assessment of vegetation carbon in the densest forests requires further research, results from this study support the use of new L-band VOD estimates for mapping the carbon of tropical forests. © 2019 Elsevier Inc." "7005369511;23101961400;","Effects of large-scale atmospheric flow and sunshine duration on the evolution of minimum and maximum temperature in Switzerland",2019,"10.1007/s00704-019-02823-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062695962&doi=10.1007%2fs00704-019-02823-x&partnerID=40&md5=f953675a9f6766d875776f370056b010","The evolution of mean annual minimum (TMIN) and maximum temperature (TMAX) on the Swiss Plateau shows distinct differences over the last 150 years. TMIN increased relatively steadily by about 3 °C. TMAX increased by only 1.5 °C with substantial decadal variability and hardly any increase until about 1940. However, in the most recent decades, TMAX trends are somewhat larger than TMIN trends. While most aspects of the TMIN evolution can be well explained by the global forcing and the modifying effects of the large-scale atmospheric flow alone, local sunshine duration (SD) information is crucial to explain major features of the TMAX series and the differences between TMIN and TMAX since about 1950. SD shows no clear trend until 1950, a decline from 1950 to 1980 and an increase since 1980 resembling the global dimming and brightening signal. TMAX is strongly influenced by SD and the TMAX evolution can be well reconstructed with local TMIN and SD. Strong TMAX declines are found from 1950 to the 1970s. TMIN shows no trend in this period. Between 1980 and about 2005, both TMIN and TMAX show strong increases caused by the greenhouse gas forcing, decreasing aerosols and probably also decreasing cloud cover. Since about 2005, the increases are weaker. The brightening has weakened and the warming effect of the continuously growing greenhouse gas forcing has additionally been reduced by cooling effects caused by large-scale atmospheric flow anomalies. The reasons for the considerable differences in the TMIN and TMAX evolution prior to 1950 remain unknown and further investigations are needed to shed more light on this disparity. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature." "26643251000;57097508500;26430815000;7003401367;57210457351;7006394349;56567688800;6603925178;6603745481;6506838812;55049964700;57207368991;42361530100;7102674341;10141275200;6507770295;7006093704;57200316012;57211321425;57218249778;57193016865;24377076700;57211311986;57210336987;57190251205;6602506180;14831630600;57195959373;35611456600;57153656200;","Retrieval of snow properties from the Sentinel-3 Ocean and Land Colour Instrument",2019,"10.3390/rs11192280","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073417696&doi=10.3390%2frs11192280&partnerID=40&md5=911e96d35a87df0d91faadf122383bb0","The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing. In this work, we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400'1020 nm, we derived important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on a spatial grid of 300 m. The algorithm also incorporated cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long-term snow property records essential for climate monitoring and data assimilation studies'especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo. © 2019 by the authors." "57192700389;8277424000;35262555900;6603768446;","Investigating the GPM Dual-frequency Precipitation Radar signatures of low-level precipitation enhancement",2019,"10.1002/qj.3611","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070797786&doi=10.1002%2fqj.3611&partnerID=40&md5=77848c933590df4b2a8ae60f92bfadf6","High-intensity precipitation represents a threat for several regions of the world because of the related risk of natural disasters (e.g. floods and landslides). This work focuses on low-level precipitation enhancement that occurs in the cloud warm layer and has been observed in relation to collision-coalescence (CC) leading to flash floods and extreme rainfall events in tropical and temperate latitudes. Specifically, signatures of precipitation enhancement (referred to as CC-dominant precipitation) are investigated in the observations from the Global Precipitation Measurement (GPM) core mission Dual-frequency Precipitation Radar (DPR) over the central/eastern Contiguous United States (CONUS) during June 2014–May 2018. A classification scheme for CC-dominant precipitation, developed for dual-polarization S-band radar measurements and applied in a previous work to X-band radar observations in complex terrain, is used as a benchmark. The scheme is here applied to the GPM ground validation dataset that matches ground-based radar observations across CONUS to space-borne DPR retrievals. The occurrence of CC-dominant precipitation is documented and the corresponding signatures of CC-dominant precipitation at Ku- and Ka-band are studied. CC-dominant profiles show distinguishing features when compared to profiles not dominated by CC, e.g. characteristic vertical slopes of reflectivity at Ku- and Ka-band in the liquid layer, lower freezing-level height, and shallower ice layer, which are linked to environmental conditions driving the peculiar CC microphysics. This work aims at improving satellite quantitative precipitation estimation, particularly GPM retrievals, by targeting CC development in precipitation columns. © 2019 Royal Meteorological Society" "56416175400;7006244721;","Processes governing the amplification of ensemble spread in a medium-range forecast with large forecast uncertainty",2019,"10.1002/qj.3617","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071249135&doi=10.1002%2fqj.3617&partnerID=40&md5=63d1ac4848ce27f4bf98fb70d95b9da3","This study provides a process-based perspective on the amplification of forecast uncertainty and forecast errors in ensemble forecasts. A case from the North Atlantic Waveguide and Downstream Impact Experiment that exhibits large forecast uncertainty is analysed. Two aspects of the ensemble behaviour are considered: (a) the mean divergence of the ensemble members, indicating the general amplification of forecast uncertainty, and (b) the divergence of the best and worst members, indicating extremes in possible error-growth scenarios. To analyse the amplification of forecast uncertainty, a tendency equation for the ensemble variance of potential vorticity (PV) is derived and partitioned into the contributions from individual processes. The amplification of PV variance is, on average for the midlatitudes of the Northern Hemisphere, dominated by near-tropopause dynamics. Locally, however, other processes can dominate the variance amplification, for example, in the region where tropical storm Karl interacts with the Rossby-wave pattern during extratropical transition. In this region, the variance amplification is dominated by upper-tropospheric divergence and tropospheric–deep interaction and is thereby mostly related to (moist baroclinic) cyclone development. The differences between the error growth in the best and worst ensemble members can, to a large part, be attributed to differences in the representation of cut-off evolution around 3 days, which subsequently amplifies substantially in the highly nonlinear region of the Rossby-wave pattern until 5 days. In terms of the processes, the differences in error growth are dominated by differences in the error growth by near-tropopause dynamics. The approach presented provides flow-dependent insight into the dynamics of forecast uncertainty and forecast errors and helps to understand better the different contributions of specific weather systems to the medium-range amplification of ensemble spread. © 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society." "57203728636;56531995000;24385191600;","Tropospheric corrections for InSAR: Statistical assessments and applications to the Central United States and Mexico",2019,"10.1016/j.rse.2019.111326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069673928&doi=10.1016%2fj.rse.2019.111326&partnerID=40&md5=836e4c5fc7a3a6d948e3b4cadd0ff96f","The rapid expansion of SAR data availability and advancements in InSAR processing methods has enabled the formation of ground displacement time series for many parts of the world where such research was previously hindered by decorrelation due to sparse temporal sampling and SAR operating frequency. In particular, free and open data access from the European Sentinel-1 constellation and the future NASA-ISRO SAR (NISAR) mission is encouraging the global community to move towards automated, cloud-based processing that can accommodate these rapidly growing data volumes and facilitate the use of a suite of corrections to the data. A key challenge is related to path delays introduced when the radar signal propagates through the troposphere. Tropospheric corrections estimated from empirical, phase-based methods and those using independent data from weather models, GPS, and radiometers have been included in open-source packages such as TRAIN, PyAPS and GACOS. Users within the InSAR community have reported varying degrees of success using these methods in a range of areas around the world. However, the various statistical metrics used to evaluate the reliability of tropospheric corrections are not consistently applied and often depend on the area and the spatial scale over which they are evaluated. Examination of a simple metric such as the overall reduction in phase variability within an interferogram does not allow the user to determine whether the improvement was at large or short length scales. We present a review of existing tropospheric correction methods and statistical performance metrics, providing guidelines for global assessment and verification of the efficacy of tropospheric correction methods. We summarize the assumptions and limitations for each correction method as well as each statistical performance metric. We examine two regions with different atmospheric characteristics - one Sentinel-1 swath covering the central United States and one swath covering south central Mexico, including part of the Pacific coast. As the SAR community moves towards reliance on global and automated InSAR processing platforms that incorporate tropospheric corrections, approaches such as those examined here can aid researchers in their efforts to evaluate such corrections and include their uncertainties in derived products such as surface displacement time series, coseismic offsets, processes that correlate with topography, and signals with smaller magnitude or larger spatial scales such as those associated with small earthquakes, aseismic creep and slow slip events. We found that the GACOS products (leveraging the operational high resolution ECMWF weather model) outperform the other correction methods explored here on average, but this result is highly dependent on location, acquisition time, and data availability. We found spatial structure functions to be most useful for performance assessment because of their ability to convey information about performance at discrete spatial scales. © 2019 Elsevier Inc." "57203364006;57191612756;35766085300;57200790631;35448188800;","Ozone Monitoring Instrument (OMI) Total Column Water Vapor version 4 validation and applications",2019,"10.5194/amt-12-5183-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072748582&doi=10.5194%2famt-12-5183-2019&partnerID=40&md5=58093e3c755fa24187f0a18a13063aac","Total column water vapor (TCWV) is important for the weather and climate. TCWV is derived from the Ozone Monitoring Instrument (OMI) visible spectra using the version 4.0 retrieval algorithm developed at the Smithsonian Astrophysical Observatory. The algorithm uses a retrieval window between 432.0 and 466.5nm and includes updates to reference spectra and water vapor profiles. The retrieval window optimization results from the trade-offs among competing factors. The OMI product is characterized by comparing against commonly used reference datasets - global positioning system (GPS) network data over land and Special Sensor Microwave Imager/Sounder (SSMIS) data over the oceans. We examine how cloud fraction and cloud-top pressure affect the comparisons. The results lead us to recommend filtering OMI data with a cloud fraction less than 0.05-0.25 and cloud-top pressure greater than 750mb (or stricter), in addition to the data quality flag, fitting root mean square (RMS) and TCWV range check. Over land, for f0.05, the overall mean of OMI-GPS is 0.32mm with a standard deviation (σ) of 5.2mm; the smallest bias occurs when TCWV10-20mm, and the best regression line corresponds to f0.25. Over the oceans, for f0.05, the overall mean of OMI-SSMIS is 0.4mm (1.1mm) with σ6.5mm (6.8mm) for January (July); the smallest bias occurs when TCWV20-30mm, and the best regression line corresponds to f0.15. For both land and the oceans, the difference between OMI and the reference datasets is relatively large when TCWV is less than 10mm. The bias for the version 4.0 OMI TCWV is much smaller than that for version 3.0. As test applications of the version 4.0 OMI TCWV over a range of spatial and temporal scales, we find prominent signals of the patterns associated with El Niño and La Niña, the high humidity associated with a corn sweat event, and the strong moisture band of an atmospheric river (AR). A data assimilation experiment demonstrates that the OMI data can help improve the Weather Research and Forecasting (WRF) model skill at simulating the structure and intensity of the AR and the precipitation at the AR landfall. © Author(s) 2019." "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." "24492361700;57193485117;57206332144;8625545200;36458493200;35494005000;7202652226;7004299722;57208460143;","The impact of neglecting ice phase on cloud optical depth retrievals from AERONET cloud mode observations",2019,"10.5194/amt-12-5087-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072607054&doi=10.5194%2famt-12-5087-2019&partnerID=40&md5=af5052ab3f5820c675853e3b91b10c16","Clouds present many challenges to climate modelling. To develop and verify the parameterisations needed to allow climate models to represent cloud structure and processes, there is a need for high-quality observations of cloud optical depth from locations around the world. Retrievals of cloud optical depth are obtainable from radiances measured by Aerosol Robotic Network (AERONET) radiometers in ""cloud mode"" using a two-wavelength retrieval method. However, the method is unable to detect cloud phase, and hence assumes that all of the cloud in a profile is liquid. This assumption has the potential to introduce errors into long-term statistics of retrieved optical depth for clouds that also contain ice. Using a set of idealised cloud profiles we find that, for optical depths above 20, the fractional error in retrieved optical depth is a linear function of the fraction of the optical depth that is due to the presence of ice cloud (""ice fraction""). Clouds that are entirely ice have positive errors with magnitudes of the order of 55% to 70%. We derive a simple linear equation that can be used as a correction at AERONET sites where ice fraction can be independently estimated. Using this linear equation, we estimate the magnitude of the error for a set of cloud profiles from five sites of the Atmospheric Radiation Measurement programme. The dataset contains separate retrievals of ice and liquid retrievals; hence ice fraction can be estimated. The magnitude of the error at each location was related to the relative frequencies of occurrence in thick frontal cloud at the mid-latitude sites and of deep convection at the tropical sites - that is, of deep cloud containing both ice and liquid particles. The long-term mean optical depth error at the five locations spans the range 2-4, which we show to be small enough to allow calculation of top-of-atmosphere flux to within 10% and surface flux to about 15%. © Author(s) 2019." "36462180600;6602182223;36134816800;8942524900;55730541100;24537168200;7006837187;7004469744;57208121852;","In situ constraints on the vertical distribution of global aerosol",2019,"10.5194/acp-19-11765-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072623045&doi=10.5194%2facp-19-11765-2019&partnerID=40&md5=d5bd03c13962779e5f30d7354353a1c5","Despite ongoing efforts, the vertical distribution of aerosols globally is poorly understood. This in turn leads to large uncertainties in the contributions of the direct and indirect aerosol forcing on climate. Using the Global Aerosol Synthesis and Science Project (GASSP) database - the largest synthesised collection of in situ aircraft measurements currently available, with more than 1000 flights from 37 campaigns from around the world - we investigate the vertical structure of submicron aerosols across a wide range of regions and environments. The application of this unique dataset to assess the vertical distributions of number size distribution and cloud condensation nuclei (CCN) in the global aerosol-climate model ECHAM-HAM reveals that the model underestimates accumulation-mode particles in the upper troposphere, especially in remote regions. The processes underlying this discrepancy are explored using different aerosol microphysical schemes and a process sensitivity analysis. These show that the biases are predominantly related to aerosol ageing and removal rather than emissions. © Author(s) 2019." "12144198300;37087012900;57205397413;6701729202;","Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties",2019,"10.5194/amt-12-5071-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072624771&doi=10.5194%2famt-12-5071-2019&partnerID=40&md5=aa09c149d794025baafb5c034eeda6f2","Improvements to climate model results in polar regions require improved knowledge of cloud properties. Surface-based infrared (IR) radiance spectrometers have been used to retrieve cloud properties in polar regions, but measurements are sparse. Reductions in cost and power requirements to allow more widespread measurements could be aided by reducing instrument resolution. Here we explore the effects of errors and instrument resolution on cloud property retrievals from downwelling IR radiances for resolutions of 0.1 to 20 cm-1. Retrievals are tested on 336 radiance simulations characteristic of the Arctic, including mixed-phase, vertically inhomogeneous, and liquid-topped clouds and a variety of ice habits. Retrieval accuracy is found to be unaffected by resolution from 0.1 to 4 cm-1, after which it decreases slightly. When cloud heights are retrieved, errors in retrieved cloud optical depth (COD) and ice fraction are considerably smaller for clouds with bases below 2 km than for higher clouds. For example, at a resolution of 4 cm-1, with errors imposed (noise and radiation bias of 0.2 mW/(m2 sr cm-1) and biases in temperature of 0.2K and in water vapor of -3 %), using retrieved cloud heights, root-mean-square errors decrease from 1.1 to 0.15 for COD, 0.3 to 0.18 for ice fraction (fice), and 10 to 7 μm for ice effective radius (errors remain at 2 μm for liquid effective radius). These results indicate that a moderately low-resolution, surface-based IR spectrometer could provide cloud property retrievals with accuracy comparable to existing higher-resolution instruments and that such an instrument would be particularly useful for low-level clouds. © Author(s) 2019." "56709590600;10141225800;7801401670;54388456400;7003414581;7003375617;57202475063;8627503500;35491260500;57197827141;10143908900;6602954401;57201722201;6602463657;57212092970;57207888214;6602185497;56333106800;6701697023;57189994953;22946301100;8302476700;57201300926;7004149770;24366038500;6701490421;57211083450;57210825776;55951906300;57200167376;57170839100;24281186100;7005659847;56151520300;56823556300;40661065000;57197720998;8927405700;36496339500;7102113229;","EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product",2019,"10.5194/acp-19-11743-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072620992&doi=10.5194%2facp-19-11743-2019&partnerID=40&md5=4e17146deb33d43bd33c1ab99a47835b","We present the evaluation activity of the European Aerosol Research Lidar Network (EARLINET) for the quantitative assessment of the Level 2 aerosol backscatter coefficient product derived by the Cloud-Aerosol Transport System (CATS) aboard the International Space Station (ISS; Rodier et al., 2015). The study employs correlative CATS and EARLINET backscatter measurements within a 50km distance between the ground station and the ISS overpass and as close in time as possible, typically with the starting time or stopping time of the EARLINET performed measurement time window within 90min of the ISS overpass, for the period from February 2015 to September 2016. The results demonstrate the good agreement of the CATS Level 2 backscatter coefficient and EARLINET. Three ISS overpasses close to the EARLINET stations of Leipzig, Germany; Évora, Portugal; and Dushanbe, Tajikistan, are analyzed here to demonstrate the performance of the CATS lidar system under different conditions. The results show that under cloud-free, relative homogeneous aerosol conditions, CATS is in good agreement with EARLINET, independent of daytime and nighttime conditions. CATS low negative biases are observed, partially attributed to the deficiency of lidar systems to detect tenuous aerosol layers of backscatter signal below the minimum detection thresholds; these are biases which may lead to systematic deviations and slight underestimations of the total aerosol optical depth (AOD) in climate studies. In addition, CATS misclassification of aerosol layers as clouds, and vice versa, in cases of coexistent and/or adjacent aerosol and cloud features, occasionally leads to non-representative, unrealistic, and cloud-contaminated aerosol profiles. Regarding solar illumination conditions, low negative biases in CATS backscatter coefficient profiles, of the order of 6.1%, indicate the good nighttime performance of CATS. During daytime, a reduced signal-to-noise ratio by solar background illumination prevents retrievals of weakly scattering atmospheric layers that would otherwise be detectable during nighttime, leading to higher negative biases, of the order of 22.3%. © Author(s) 2019." "54408354000;7003942283;","Ice Nucleation of Model Nanoplastics and Microplastics: A Novel Synthetic Protocol and the Influence of Particle Capping at Diverse Atmospheric Environments",2019,"10.1021/acsearthspacechem.9b00132","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072561230&doi=10.1021%2facsearthspacechem.9b00132&partnerID=40&md5=0505ad9d36ce698a7f6a990c3c246218","Little is known about airborne atmospheric aerosols containing emerging contaminants such as nano- and microplastics. A novel, minimum energy usage, synthetic protocol of plastic micro/nanoparticles was herein developed. Stable plastic hydrosols were synthesized and characterized using three different types of plastics. The ice nucleation efficiency (INE) was investigated in both normal and synthetic seawater to mimic environmental ice nucleation. Among the three tested plastic precursors (low-density polyethylene, high-density polyethylene, and polypropylene), polypropylene produced the highest particle density with narrow particle size distribution. The change of size, shape, surface charge, and electronic behavior of the plastic nano- and microparticles accounted for the altered INE. The effects of environmental factors such as particle acidity and temperature on ice nucleation were also examined. An increase in pH increased INE due to an increased particle density (number of particles per unit volume), whereas increased temperature decreased INE significantly due to aggregation (attaching particles to produce a larger particle). Four types of capping were used on the surfaces of nano- and microplastics to investigate how the plastics act to nucleate ice when mixed with different particles. They include (a) ZnO as an emerging metal contaminant, (b) kaolin as a clay mineral, (c) HgCl2 as a toxic ionic water pollutant, and (d) phenanthrene as a polycyclic aromatic hydrocarbon. Capping by ZnO and HgCl2 decreased the INE of plastic nano- and microparticles, whereas kaolin and phenanthrene enhanced INE significantly. The association of contaminants to micro- and nanoplastics changes INE likely due to water affinity, surface buckling, and lattice mismatch energy of ice, affecting ice nuclei formation processes. The observed differential physicochemical behaviors of nano- and microplastics, with and without co-contaminant cappings, provide further insights to understand natural environmental ice nucleation and precipitation events. Our work shows that future emissions of nano- and microplastics may become important for cloud formation and thus anthropogenic climate change. Copyright © 2019 American Chemical Society." "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.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)."
"56596869400;57112885800;22982141200;55621033900;57204010573;36562846200;57214906099;57200232333;","Decrease in light precipitation events in Huai River Eco-economic Corridor, a climate transitional zone in eastern China",2019,"10.1016/j.atmosres.2019.04.027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064907630&doi=10.1016%2fj.atmosres.2019.04.027&partnerID=40&md5=c7acfc05218faf7a117bfa0ef2cb3e27","Light precipitation events generally occur much more frequently than events of other precipitation intensities. Changes in light precipitation amounts and days (length) over time have profound implications for climate change. There is a lack of quantitative monitoring indicators or in-depth analysis techniques for atmospheric circulation mechanisms of regional light precipitation events, especially in climate transitional zones. The Huai River Eco-economic Corridor (HREC) served as a case area in this study as we assessed trends in light precipitation events and their possible atmospheric circulation mechanisms. A significant decreasing trend in the light precipitation events is observed and appears to be mainly concentrated in the lower intensities (0.1 ≤ P<2 mm/day). The decreasing trend is more obvious for consecutive than discrete light precipitation events. The mutation points for annual consecutive light precipitation events were found in 1977/1978, and averages in the later years of the observation period (1978–2014) fell significantly below those of the earlier period (1961–1977). Atmospheric circulation variables corresponding to the light precipitation days with intensity of 0.1–2 mm/day revealed that the decreasing trends in water vapor transport budgets, low cloud cover, and total column cloud liquid water may be the primary causes of decreased light precipitation events. The decreasing trends in light precipitation events were also likely attributable to increases in water vapor flux divergence, air temperature, and vertical velocity values. © 2019 Elsevier B.V."
"55286622100;55547738500;56087936200;56911370400;57199645421;57205514998;56609491700;57205516820;57204711954;55664298600;","Concentrations, optical and radiative properties of carbonaceous aerosols over urban Lanzhou, a typical valley city: Results from in-situ observations and numerical model",2019,"10.1016/j.atmosenv.2019.06.046","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067672720&doi=10.1016%2fj.atmosenv.2019.06.046&partnerID=40&md5=924de686c4a0d022500771aeb199c33f","The concentrations, optical and radiative effects of carbonaceous aerosols were essential to studies of the climatic, environmental and health effects. The previous studies less combined numerical simulation with in-situ observations, especially for the aerosol vertical profiles. In this study, we off-line measured vertical profiles of submicron black carbon (BC) aerosols and on-line obtained aerosol optical properties over urban Lanzhou during 26 December 2017 to 11 January 2018. The BC optical properties and radiative effects were evaluated using Optical Properties of Aerosols and Clouds (OPAC) and Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) models. The absorption and scattering coefficients and optical depth of BC aerosols ranged from 9 to 83 M m−1, 3–24 M m−1 and 0.02 to 0.2 respectively, which in average accounted for 50%, 3% and 11% of the optical properties of total aerosols during the study period. BC aerosol radiative forcing (ARF) within ATMOS (top-surface) varying from 16.6 to 108.8 W m−2 accounted for 17.3%–97.4% of total aerosols ARF with an average of 66.6%, and the percentages increased significantly as BC concentrations increased during the period. The mean atmospheric heating rate (AHR) induced by BC aerosols was 1.94 K day−1 ranging from 0.46 to 3.03 K day−1 during the study period. This study contributes to understanding the impacts of light-absorbing aerosols on climate and haze pollution in an urban valley. © 2019 Elsevier Ltd"
"57209841086;22978652800;14021975100;","Assessments of the night-time and daytime radiative fluxes balance on seasonal timescale over West Africa",2019,"10.1016/j.jastp.2019.05.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067798879&doi=10.1016%2fj.jastp.2019.05.012&partnerID=40&md5=1e11845e0bab330aa2ef0d7ba0f73cc4","The main aim of this paper is to assess the impact of climate change on variations and trends of the net radiation flux over West Africa during night and day time. West Africa was sub-divided into six climatic zones as classified by the World Meteorological Organization such as Hyper-Arid (HAR), Arid (ARD), Semi-Arid (SAR), Semi-Humid Dry (SHD), Semi-Humid Humid (SHH) and Humid (HUM) zones. To achieve this aim, thirty-six years' surface data of shortwave and longwave radiations between 1980 and 2015 were obtained from the Archives of the Modern-Era Retrospective Analysis for Research and Application, Version 2 (MERRA-2) database. Analyses showed that the maximum values of net radiative fluxes during the nighttime and daytime have the magnitude in watt per square metres of −70.00 and 225.82 in HAR zone, −62.46 and 248.99 in ARD zone, −51.71 and 304.88 in SAR zone, −40.55 and 334.58 in SHD zone, −34.32 and 352.62 in SHH zone and −30.49 and 362.68 in HUM zone respectively. The effect of population density, emission of greenhouse gas and surface albedo on net radiation was investigated over the climatic zones using the multivariate linear regression analysis. The results of the regression analysis showed that they have significant effects on net radiation. Also, the monotonic trend analysis between 1980 and 2015 was carried out using the non-parametric Mann- Kendall statistical test. The results of the trend test revealed that net radiation showed decreasing trends mainly in the humid zones at over 95% significance level while population density, emission of greenhouse gas and surface albedo showed significant increasing trends at the 99.9% level of significance. The analyses showed that the humid zones have higher values of net radiation, radiative cloud forcing, carbon-dioxide emission, population density and lower surface albedo than arid zones. Therefore, as signatures of climate change, it can be concluded that increase in population density, cloud amount and anthropogenic activities such as land use/land cover and emission of greenhouse gas have contributed greatly to the significant decreasing trends of the radiative flux balance especially in the humid zones of West Africa. © 2019 Elsevier Ltd"
"57191839889;56135550100;55821960900;","An improved surface soil moisture downscaling approach over cloudy areas based on geographically weighted regression",2019,"10.1016/j.agrformet.2019.05.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066244761&doi=10.1016%2fj.agrformet.2019.05.022&partnerID=40&md5=8a94db8ed83f0a64424b85016c53abb1","This study proposed a methodological framework for downscaling AMSR-2 surface soil moisture (SSM) products over cloudy areas using MODIS LST/NDVI datasets. The experiment was conducted in a relatively large area of 430,000 km2 in the middle and lower reaches of the Yangtze and Huaihe rivers in China, which is characterized by humid climate and frequent cloudy weather conditions. As MODIS LSTs suffer from serious pixel loss due to cloud interference in this area, an effective LST interpolation method was preliminarily applied to achieve daily LST datasets with quasi-full covers. And rather small RMSEs in the range 1.5 K–3.5 K were obtained when the interpolated LST datasets were validated against a reference LST dataset built from observed relationships between LST and ground-based near-surface air temperatures on clear sky days. A regression equation was then established between AMSR-2 SSM and spatially resampled MODIS datasets using “Geographically Weighted Regression (GWR)” to implement the SSM downscaling process. SSM estimates downscaled by the GWR-based method showed a better performance over those downscaled by the traditional “universal triangle feature (UTF)” based method in view of their “non-biased RMSEs (ubRMSEs)”, correlation coefficients, and mean biases with respect to ground-based soil moisture validation data. Comparisons between SSM estimates from MODIS LST inputs and those from interpolated LST inputs were conducted, and they showed that the SSM estimates downscaled by interpolated LST inputs performed only slightly poorer (with an ubRMSE difference no larger than 0.02 cm3/cm3) than those by MODIS data. Time series analysis further showed that the GWR-based downscaled SSM estimates with reconstructed LST data inputs are in phase with the variation in ground-based soil moisture with the exception of areas of extremely high vegetation cover or low temperatures. The framework proposed in this study thus proved feasible for the derivation of reliable downscaled high spatial resolution SSM estimates, an essential application in mitigating pixel loss under cloudy weather conditions. © 2019 Elsevier B.V."
"56708460400;34870277200;55751665200;57193926688;55239907200;","Revised cloud and convective parameterization in CFSv2 improve the underlying processes for northward propagation of Intraseasonal oscillations as proposed by the observation-based study",2019,"10.1007/s00382-019-04657-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061288330&doi=10.1007%2fs00382-019-04657-9&partnerID=40&md5=2d1c9865bf05852e4cafd750104cc6be","The performance of revised climate forecast system version 2 (CFSv2) are evaluated on the simulation of the underlying cloud and convective processes associated with the strong and weak boreal summer intraseasonal oscillations (BSISOs) events. The revised version of the CFSv2 consists of a six-class Weather Research Forecasting single moment (WSM6) cloud microphysics scheme and the default version has Zhao and Carr (ZC) cloud microphysics scheme. Both the version uses revised simplified Arakawa-Schubert (RSAS) convection scheme. The study reveals that the revised version of CFSv2 (RSAS-WSM) is able to better simulate the northward propagation of BSISOs and associated dynamical and thermodynamical mechanism put forward by earlier observation-based studies. It is found that the large-scale organized northwest-southeast tilted structure of rain band is better captured in RSAS-WSM simulation as compared to the default version of CFSv2 (RSAS-ZC) during strong BSISO events. Further, the reasonable large-scale or stratiform rainfall associated with the northward propagating strong BSISO events is seen in RSAS-WSM while it is completely missing in RSAS-ZC simulation. The pressure-latitude profiles of cloud liquid water (CLW) and cloud ice (CLI) show more realistic steady northward propagation in RSAS-WSM simulation. Consistent with the CLW and CLI distribution and their influence on the large-scale heating structure, the large-scale condensation heating shows quasi-periodic northward propagation in RSAS-WSM whereas such type of distribution is not captured in RSAS-ZC simulation. The realistic representation of cloud processes in WSM leads to simulate reasonable dynamical and thermodynamical processes associated with the strong BSISO events which follows the observation-based hypothesis proposed by earlier studies. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"57195776701;13204458100;8615886200;55927053800;36722293600;35569803200;","Satellite inference of water vapour and above-cloud aerosol combined effect on radiative budget and cloud-Top processes in the southeastern Atlantic Ocean",2019,"10.5194/acp-19-11613-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072262163&doi=10.5194%2facp-19-11613-2019&partnerID=40&md5=06081af4efcb2f6cd43cb61c8a2f6e21","Aerosols have a direct effect on the Earth's radiative budget and can also affect cloud development and lifetime, and the aerosols above clouds (AAC) are particularly associated with high uncertainties in global climate models. Therefore, it is a prerequisite to improve the description and understanding of these situations. During the austral winter, large loadings of biomass burning aerosols originating from fires in the southern African subcontinent are lifted and transported westwards, across the southeastern Atlantic Ocean. The negligible wet scavenging of these absorbing aerosols leads to a near-persistent smoke layer above one of the largest stratocumulus cloud decks on the planet. Therefore, the southeastern Atlantic region is a very important area for studying the impact of above-cloud absorbing aerosols, their radiative forcing and their possible effects on clouds. In this study we aim to analyse and quantify the effect of smoke loadings on cloud properties using a synergy of different remote sensing techniques from A-Train retrievals (methods based on the passive instruments POLDER and MODIS and the operational method of the spaceborne lidar CALIOP), collocated with ERA-Interim re-analysis meteorological profiles. To analyse the possible mechanisms of AAC effects on cloud properties, we developed a high and low aerosol loading approach, which consists in evaluating the change in radiative quantities (i.e. cloud-top cooling, heating rate vertical profiles) and cloud properties with the smoke loading. During this analysis, we account for the variation in the meteorological conditions over our sample area by selecting the months associated with one meteorological regime (June-August). The results show that the region we focus on is primarily under the energetic influence of absorbing aerosols, leading to a significant positive shortwave direct effect at the top of the atmosphere. For larger loads of AACs, clouds are optically thicker, with an increase in liquid water path of 20 gm 2 and lower cloud-top altitudes by 100 m. These results do not contradict the semi-direct effect of above-cloud aerosols, explored in previous studies. Furthermore, we observe a strong covariance between the aerosol and the water vapour loadings, which has to be accounted for. A detailed analysis of the heating rate profiles shows that within the smoke layer, the absorbing aerosols are 90% responsible for warming the ambient air by approximately 5.7Kd 1. The accompanying water vapour, however, has a longwave effect at distance on the cloud top, reducing its cooling by approximately 4.7Kd 1 (equivalent to 7 %). We infer that this decreased cloud-top cooling in particular, in addition with the higher humidity above the clouds, might modify the cloud-top entrainment rate and its effect, leading to thicker clouds. Therefore, smoke (the combination of aerosol and water vapour) events would have the potential to modify and probably reinforce the underlaying cloud cover. © Author(s) 2019."
"7004720603;57206239913;36654666600;55432802300;57206274992;57202087584;35745065400;55922913900;6602195054;24511929800;","Temperature variability and soil–atmosphere interaction in South America simulated by two regional climate models",2019,"10.1007/s00382-019-04668-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061642777&doi=10.1007%2fs00382-019-04668-6&partnerID=40&md5=ec2b0cb077fc0d3271d9a8068ac626f3","Interannual variability of surface air temperature over South America is investigated and, based on previous studies, thought to be partly the consequence of soil–atmosphere interaction. Annual and monthly averages of surface air temperature, evapotranspiration, heat fluxes, surface radiation and cloud cover, simulated by two regional climate models, RCA4 and LMDZ, were analyzed. To fully reveal the role of soil as a driver of temperature variability, simulations were performed with and without soil moisture-atmosphere coupling (Control and Uncoupled). Zones of large variance in air temperature and strong soil moisture-atmosphere coupling are found in parts of La Plata Basin and in eastern Brazil. The two models show different behaviors in terms of coupling magnitude and its geographical distribution, being the coupling strength higher in RCA4 and weaker in LMDZ. RCA4 also shows greater amplitude of the annual cycle of the monthly surface air temperature compared to LMDZ. In both regions and for both models, the Uncoupled experiment tends to be colder and exhibits smaller amplitude of the interannual variability and larger evaporative fraction than the Control does. It is evidenced that variability of the land surface affects, and is affected by, variability of the surface energy balance and that interannual temperature variability is partly driven by land–atmosphere interaction. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"7103180783;53880473700;6602080205;7402401574;","Impacts of recent decadal changes in Asian aerosols on the East Asian summer monsoon: roles of aerosol–radiation and aerosol–cloud interactions",2019,"10.1007/s00382-019-04698-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062783893&doi=10.1007%2fs00382-019-04698-0&partnerID=40&md5=8b9d762e92a500606ac1c6ff306ccfae","Anthropogenic aerosols (AA) can affect cloud and precipitation through aerosol–radiation interaction (ARI) and aerosol–cloud interaction (ACI). Over the past few decades, anthropogenic aerosol emissions have exhibited remarkable changes in the magnitude and in spatial pattern. The most significant changes are the increased emissions over both South Asia and East Asia. In this study, the atmospheric component of a state-of-the-art climate model that includes eight species of tropospheric aerosols, coupled to a multi-level mixed-layer ocean model, has been used to investigate the impacts of Asian anthropogenic aerosol precursor emission changes from 1970s to 2000s on large scale circulation and precipitation in boreal summer over East Asia. Results reveal significant changes in circulation and clouds over East Asia and over the tropical and western North Pacific (WNP). Increased Asian AA emissions lead to anomalous cyclonic circulation over the Maritime continent (MC) and anomalous anticyclonic circulation over the WNP, resulting in anomalous moisture transport convergence over the MC and therefore increased precipitation. They also lead to anomalous moisture flux divergence over both the WNP and large land areas of East Asia, especially over northern China, and therefore decreased precipitation there. These large scale circulation anomalies over the adjacent oceans are related to aerosol change induced ocean feedbacks, predominantly through ACI. It is the slow responses over the adjacent oceans (e.g., SST changes) through coupled atmosphere–ocean interaction in pre-monsoon seasons and summer that shape the changes of the East Asian summer monsoon and local precipitation. The results in this study suggest that increased Asian AA emissions from 1970s to 2000s may have played an important role for the observed southward shift of the Pacific intertropical convergence zone and precipitation belt, weakening of East Asian summer monsoon and reduced precipitation over northern China in East Asia during the latter half of the twentieth century. © 2019, The Author(s)."
"35746036000;55922913900;55937180800;7004472363;","Heavy rainfall in Mediterranean cyclones, Part II: Water budget, precipitation efficiency and remote water sources",2019,"10.1007/s00382-019-04639-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061296547&doi=10.1007%2fs00382-019-04639-x&partnerID=40&md5=a8248c536974498b21c34ea6d58e7c4e","In this study, we use convection-permitting high resolution (3 km) simulations to quantify and analyse the water budget, precipitation efficiency and water sources of 100 intense Mediterranean cyclones. To this end, we calculate the water content, advection and microphysical processes of water vapour and rain water by implementing new diagnostics to the Weather Research and Forecasting (WRF) model. The 100 intense cyclones have been randomly selected from a 500 intense cyclones dataset, identified and tracked in an 11-year time period in part I of this study. Results are presented in a composite approach showing that most rainfall takes place to the north-east side of the cyclones, close to their centre. Rainfall location is concomitant to the area of horizontal moisture flux convergence and is quasi-equal to the amount of water vapour loss due to microphysical processes. Similar results were found regardless if cyclones produce high or low rainfall amounts. Vertical profiles of the water budget terms revealed deeper clouds for the cyclones producing high rainfall, consistent with higher values of vertical advection of both water vapour and rain water. Finally, cyclones were analysed with respect to their precipitation efficiency, i.e. the ratio between the rainwater produced in an atmospheric column and the consequent rainfall, and showed that cyclones tend to be more efficient when their rainfall production takes place over land. Therefore, there is a complex relation between water vapour advection, precipitation efficiency and rainfall which is discussed through the comparison of two tropical-like cyclones with two cyclones that produced low rainfall amounts. Finally, our analysis is complemented by applying a Lagrangian approach to all 100 cyclones in order to quantify the water vapour source regions that contribute to the cyclones’ rainfall due to local surface evaporation. Results showed that these regions are located over both the Atlantic and the Mediterranean, however we show that cyclones producing high rainfall are related with higher water transport from both the subtropical Atlantic and the Mediterranean Sea. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"7404548584;6701718281;14622650300;7101984634;35263854800;57203233100;7005420497;39561656500;57203378050;35396858200;57194228711;6506458269;7006783796;7004433410;6603768446;7004678728;6505576518;18134565600;","Observations and hypotheses related to low to middle free tropospheric aerosol, water vapor and altocumulus cloud layers within convective weather regimes: A SEAC4RS case study",2019,"10.5194/acp-19-11413-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072168974&doi=10.5194%2facp-19-11413-2019&partnerID=40&md5=47eeccc5b0c6cd7bce3be1d1d9dfc359","The NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) project included goals related to aerosol particle life cycle in convective regimes. Using the University of Wisconsin High Spectral Resolution Lidar system at Huntsville, Alabama, USA, and the NASA DC-8 research aircraft, we investigate the altitude dependence of aerosol, water vapor and Altocumulus (Ac) properties in the free troposphere from a canonical 12 August 2013 convective storm case as a segue to a presentation of a mission-wide analysis. It stands to reason that any moisture detrainment from convection must have an associated aerosol layer. Modes of covariability between aerosol, water vapor and Ac are examined relative to the boundary layer entrainment zone, 0 °C level, and anvil, a region known to contain Ac clouds and a complex aerosol layering structure (Reid et al., 2017). Multiple aerosol layers in regions warmer than 0 °C were observed within the planetary boundary layer entrainment zone. At 0 °C there is a proclivity for aerosol and water vapor detrainment from storms, in association with melting level Ac shelves. Finally, at temperatures colder than 0 °C, weak aerosol layers were identified above Cumulus congestus tops (∼ 0 and ∼-20 °C). Stronger aerosol signals return in association with anvil outflow. In situ data suggest that detraining particles undergo aqueous-phase or heterogeneous chemical or microphysical transformations, while at the same time larger particles are being scavenged at higher altitudes leading to enhanced nucleation. We conclude by discussing hypotheses regarding links to aerosol emissions and potential indirect effects on Ac clouds. © 2019 Author(s)."
"57193882808;","Separating physical impacts from natural variability using piggybacking (master-slave) technique",2019,"10.5194/adgeo-49-105-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072124000&doi=10.5194%2fadgeo-49-105-2019&partnerID=40&md5=43d01cf4131bfb2242193ab79fcb3636","In a chaotic system, like moist convection, it is difficult to separate the impact of a physical process from effects of natural variability. This is because modifying even a small element of the system physics typically leads to a different system evolution and it is difficult to tell whether the difference comes from the physical impact or it merely represents a different flow realization. This paper discusses a relatively simple and computationally efficient modelling methodology that allows separation of the two. The methodology is referred to as the piggybacking or the master-slave approach. The idea is to use two sets of thermodynamic variables (the temperature, water vapor, and all aerosol, cloud, and precipitation variables) in a single cloud simulation. The two sets differ in a specific element of the physics, such as aerosol properties, microphysics parameterization, large-scale forcing, environmental profiles, etc. One thermodynamic set is coupled to the dynamics and drives the simulated flow, and the other set piggybacks the flow, that is, thermodynamic variables are carried by the flow but they do not affect it. By switching the two sets (i.e. the set driving the simulation becomes the piggybacking one, and vice versa), the impact on the cloud dynamics can be evaluated. This paper provides details of the method and reviews results of its application to such problems as the postulated deep convection invigoration in polluted environments, the impact of changes in environmental profiles (e.g., due to climate change) on convective dynamics, and the role of cloud-layer heterogeneities for shallow convective cloud field evolution. Prospects for applying piggybacking technique to other areas of atmospheric simulation (e.g., weather prediction or geoengineering) are also mentioned. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License."
"7801401670;15059495000;6701378450;7003414581;57188702132;57189994953;35173744200;35771409400;24366038500;8927405700;57189992504;24437444900;17341189400;22133985200;55704350200;10141225800;","Retrieval of ice-nucleating particle concentrations from lidar observations and comparison with UAV in situ measurements",2019,"10.5194/acp-19-11315-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072131232&doi=10.5194%2facp-19-11315-2019&partnerID=40&md5=aebf7f0e404a8a7594b9d00583bd0aa5","Aerosols that are efficient ice-nucleating particles (INPs) are crucial for the formation of cloud ice via heterogeneous nucleation in the atmosphere. The distribution of INPs on a large spatial scale and as a function of height determines their impact on clouds and climate. However, in situ measurements of INPs provide sparse coverage over space and time. A promising approach to address this gap is to retrieve INP concentration profiles by combining particle concentration profiles derived by lidar measurements with INP efficiency parameterizations for different freezing mechanisms (immersion freezing, deposition nucleation). Here, we assess the feasibility of this new method for both ground-based and spaceborne lidar measurements, using in situ observations collected with unmanned aerial vehicles (UAVs) and subsequently analyzed with the FRIDGE (FRankfurt Ice nucleation Deposition freezinG Experiment) INP counter from an experimental campaign at Cyprus in April 2016. Analyzing five case studies we calculated the cloud-relevant particle number concentrations using lidar measurements (n250;dry with an uncertainty of 20 % to 40 % and Sdry with an uncertainty of 30 % to 50 %), and we assessed the suitability of the different INP parameterizations with respect to the temperature range and the type of particles considered. Specifically, our analysis suggests that our calculations using the parameterization of Ullrich et al. (2017) (applicable for the temperature range -50 to -33 ?C) agree within 1 order of magnitude with the in situ observations of nINP; thus, the parameterization of Ullrich et al. (2017) can efficiently address the deposition nucleation pathway in dust-dominated environments. Additionally, our calculations using the combination of the parameterizations of DeMott et al. (2015, 2010) (applicable for the temperature range -35 to -9 ?C) agree within 2 orders of magnitude with the in situ observations of INP concentrations (nINP) and can thus efficiently address the immersion/condensation pathway of dust and nondust particles. The same conclusion is derived from the compilation of the parameterizations of DeMott et al. (2015) for dust and Ullrich et al. (2017) for soot. © 2019 Author(s)."
"34976345200;7004620320;","Developing a monthly radiative kernel for surface albedo change from satellite climatologies of Earth's shortwave radiation budget: CACK v1.0",2019,"10.5194/gmd-12-3975-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072181107&doi=10.5194%2fgmd-12-3975-2019&partnerID=40&md5=b0e1cacb769ad57d6185a267d2e2df4e","Due to the potential for land-use-land-cover change (LULCC) to alter surface albedo, there is need within the LULCC science community for simple and transparent tools for predicting radiative forcings (F) from surface albedo changes (αs). To that end, the radiative kernel technique - developed by the climate modeling community to diagnose internal feedbacks within general circulation models (GCMs) - has been adopted by the LULCC science community as a tool to perform offline F calculations for αs. However, the codes and data behind the GCM kernels are not readily transparent, and the climatologies of the atmospheric state variables used to derive them vary widely both in time period and duration. Observation-based kernels offer an attractive alternative to GCM-based kernels and could be updated annually at relatively low costs. Here, we present a radiative kernel for surface albedo change founded on a novel, simplified parameterization of shortwave radiative transfer driven with inputs from the Clouds and the Earth's Radiant Energy System (CERES) Energy Balance and Filled (EBAF) products. When constructed on a 16-year climatology (2001-2016), we find that the CERES-based albedo change kernel - or CACK - agrees remarkably well with the mean kernel of four GCMs (rRMSE Combining double low line 14 %). When the novel parameterization underlying CACK is applied to emulate two of the GCM kernels using their own boundary fluxes as input, we find even greater agreement (mean rRMSE Combining double low line 7.4 %), suggesting that this simple and transparent parameterization represents a credible candidate for a satellite-based alternative to GCM kernels. We document and compute the various sources of uncertainty underlying CACK and include them as part of a more extensive dataset (CACK v1.0) while providing examples showcasing its application. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License."
"7202800511;","Propagation of Error and the Reliability of Global Air Temperature Projections",2019,"10.3389/feart.2019.00223","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072839094&doi=10.3389%2ffeart.2019.00223&partnerID=40&md5=f2cdfca2e0d9b6a2a3f24d3ef710178d","The reliability of general circulation climate model (GCM) global air temperature projections is evaluated for the first time, by way of propagation of model calibration error. An extensive series of demonstrations show that GCM air temperature projections are just linear extrapolations of fractional greenhouse gas (GHG) forcing. Linear projections are subject to linear propagation of error. A directly relevant GCM calibration metric is the annual average ±12.1% error in global annual average cloud fraction produced within CMIP5 climate models. This error is strongly pair-wise correlated across models, implying a source in deficient theory. The resulting long-wave cloud forcing (LWCF) error introduces an annual average ±4 Wm–2 uncertainty into the simulated tropospheric thermal energy flux. This annual ±4 Wm–2 simulation uncertainty is ±114 × larger than the annual average ∼0.035 Wm–2 change in tropospheric thermal energy flux produced by increasing GHG forcing since 1979. Tropospheric thermal energy flux is the determinant of global air temperature. Uncertainty in simulated tropospheric thermal energy flux imposes uncertainty on projected air temperature. Propagation of LWCF thermal energy flux error through the historically relevant 1988 projections of GISS Model II scenarios A, B, and C, the IPCC SRES scenarios CCC, B1, A1B, and A2, and the RCP scenarios of the 2013 IPCC Fifth Assessment Report, uncovers a ±15 C uncertainty in air temperature at the end of a centennial-scale projection. Analogously large but previously unrecognized uncertainties must therefore exist in all the past and present air temperature projections and hindcasts of even advanced climate models. The unavoidable conclusion is that an anthropogenic air temperature signal cannot have been, nor presently can be, evidenced in climate observables. © Copyright © 2019 Frank."
"7103246957;57211157798;7102933062;","Near-Surface Biases in ERA5 Over the Canadian Prairies",2019,"10.3389/fenvs.2019.00129","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072845790&doi=10.3389%2ffenvs.2019.00129&partnerID=40&md5=fd60e450264cf990904cc5827d9c0934","We quantify the biases in the diurnal cycle of air temperature in ERA5, using hourly climate station data for four stations in Saskatchewan, Canada. Compared with ERA-Interim, the biases in ERA5 have been greatly reduced, and show no differences with snow cover. We compute fits to the ERA5 mean air temperature biases based on ERA5 effective cloud albedo. They can be used to improve the ERA5 diurnal cycle of air temperature for modeling agricultural processes. Diurnally, ERA5 has a negative wind speed bias, which increases quasi-linearly with wind speed, and is greater in the daytime than at night. We evaluate ERA5 precipitation against the original climate station precipitation data, and a second generation adjusted precipitation dataset by Mekis and Vincent (2011). For the warm season, ERA5 has a high bias of 8 ± 9% above the Mekis dataset. ERA5 is −22 ± 7% below the Mekis estimate in winter, suggesting that their correction with snow may be too large. It is likely that the ERA5 precipitation bias is small, which is encouraging for agricultural modeling. Data from a BSRN site near Regina shows that the biases in the downwelling shortwave and longwave radiation estimates in ERA5 are small, and have changed little from ERA-Interim. We show that the annual cycle of the Saskatchewan surface energy and water budgets in ERA5 are realistic. In particular the damping of extremes in summer precipitation by the extraction of soil water is comparable in ERA5 to our earlier observational estimate based on gravity satellite data. © Copyright © 2019 Betts, Chan and Desjardins."
"27467630500;15749910600;57207259191;56374279300;12039851000;7004142910;7003897194;","Size-dependent ice nucleation by airborne particles during dust events in the eastern Mediterranean",2019,"10.5194/acp-19-11143-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072027692&doi=10.5194%2facp-19-11143-2019&partnerID=40&md5=56e213be84c366766144900c71d25b7e","The prediction of cloud ice formation in climate models remains a challenge, partly due to the complexity of ice-related processes. Mineral dust is a prominent aerosol in the troposphere and is an important contributor to ice nucleation in mixed-phase clouds, as dust can initiate ice heterogeneously at relatively low supercooling conditions. We characterized the ice nucleation properties of size-segregated mineral dust sampled during dust events in the eastern Mediterranean. The sampling site allowed us to compare the properties of airborne dust from several sources with diverse mineralogy that passed over different atmospheric paths. We focused on particles with six size classes determined by the Micro-Orifice Uniform Deposit Impactor (MOUDI) cutoff sizes: 5.6, 3.2, 1.8, 1.0, 0.6 and 0.3 μm. Ice nucleation experiments were conducted in theWeizmann Supercooled Droplets Observation on a Microarray (WISDOM) setup, whereby the particles are immersed in nanoliter droplets using a microfluidics technique. We observed that the activity of airborne particles depended on their size class; supermicron and submicron particles had different activities, possibly due to different composition. The concentrations of ice-nucleating particles and the density of active sites (ns) increased with the particle size and particle concentration. The supermicron particles in different dust events showed similar activity, which may indicate that freezing was dominated by common mineralogical components. Combining recent data of airborne mineral dust, we show that current predictions, which are based on surface-sampled natural dust or standard mineral dust, overestimate the activity of airborne dust, especially for the submicron class. Therefore, we suggest including information on particle size in order to increase the accuracy of ice formation modeling and thus weather and climate predictions. © Author(s) 2019."
"57212988186;22934904700;55471474500;7401945370;10243650000;56520853700;","Responses of Clouds and Large-Scale Circulation to Global Warming Evaluated From Multidecadal Simulations Using a Global Nonhydrostatic Model",2019,"10.1029/2019MS001658","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073787477&doi=10.1029%2f2019MS001658&partnerID=40&md5=ac03f1977ebe0c001bccfb71e52f87f4","This is the first paper that analyzes data from atmosphere model intercomparison project-type climate simulations using a cloud-system-resolving global nonhydrostatic model without cumulus parameterization focussing particulaly on the relationship between clouds and circulation, and their changes due to global warming. The decrease in fractional coverage of low clouds is key to evaluating cloud radiative effects, because changes in shortwave cloud radiative effects overwhelm those of longwave cloud radiative effects. Thus, improved evaluation of low clouds is important, even in high-resolution climate simulations. An analysis of heat redistribution by explicitly computed clouds revealed that column-integrated heating rate due to phase changes correlates highly with vertical velocity at the altitude corresponding to 500 hPa and is closely linked to column water vapor, similar to the present climate result. Using data from year 1 to year 5, the effective climate sensitivity was evaluated to be 3.6−3.7°C. Possible convective aggregation is also examined using an index of modified subsidence fraction and characteristic changes in the number of cold pools. Despite previous idealized-planet simulations showing more aggregated tropical convection under warmer conditions, here we show a decrease in the subsidence fraction and an increase in the number of smaller cold pools, suggesting that it is possible to realize less convective organization with warming under real atmospheric conditions. ©2019. The Authors."
"6701735773;36096767000;23981063100;21740519000;23768540500;54883121500;54893098900;6505465237;","Unified Parameterization of Convective Boundary Layer Transport and Clouds With the Thermal Plume Model",2019,"10.1029/2019MS001666","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072189281&doi=10.1029%2f2019MS001666&partnerID=40&md5=f8f5faf789f3d480e186b1a54620bb57","The representation of stratocumulus clouds, and of the stratocumulus to cumulus transitions which are ubiquitous features of marine boundary layer clouds, remains a challenge for climate models. We show how a mass flux representation of boundary layer convective structures combined with an eddy diffusivity scheme, the “thermal plume model,” first developed to represent cumulus clouds, can also adequately simulate stratocumulus and the stratocumulus to cumulus transition in a climate model. To achieve this, the detrainment formulation, in which detrainment increases for increasing negative buoyancy, has to be slightly modified: the buoyancy of a thermal plume parcel of air is computed by comparing the virtual potential temperature θv,th of the parcel with that of the surrounding environment θv,env at a given distance above instead of at the same level. This is consistent with the picture of detrained air parcels that experience some overshoot and reach a final destination at a level lower than the one at which they effectively leave the cloud or organized convective plume. The impacts of this modification are documented both for selected cases of stratocumulus, in comparison with large-eddy simulations, and in full 3-D climate simulations, in comparison with satellite observations of cloud cover. The modified scheme provides a uniform treatment of the dry convective boundary layer, of cumulus clouds, of stratocumulus, and of the transition from stratocumulus to cumulus. It is included in the most recent version of the LMDZ atmospheric general circulation model. ©2019. The Authors."
"56167179800;57151771800;55487986000;55418587000;","The Semidirect Effect of Combined Dust and Sea Salt Aerosols in a Multimodel Analysis",2019,"10.1029/2019GL084590","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071779996&doi=10.1029%2f2019GL084590&partnerID=40&md5=3005fbd0c7970ad8cd0c259fc68f3b14","To date, very few studies have focused on dust and sea salt cloud interactions, particularly the semidirect effect (SDE) that results from changes in column temperature and moisture. Here, we isolate the SDE using several climate models driven by semiempirical dust and sea salt direct radiative effects. The global annual mean SDE varies from 0.01 to 0.10 W/m2, with the bulk of the signal coming from an increase in shortwave radiation. This is consistent with decreases in low cloud over ocean due to cloud burn-off and reductions in midlevel cloud over land due to atmospheric stabilization and decreased convection. Overall, longwave effects weaken the positive SDE but with opposing effects over land and sea. High cloud is reduced over land but enhanced over sea. We conclude that dust and sea salt likely exert a global mean warming effect through cloud rapid adjustments. © 2019. The Authors."
"7005354212;22234180300;24757696000;57197754464;6602600408;57211010944;","A methodology for verifying cloud forecasts with VIIRS imagery and derived cloud products-A WRF case study",2019,"10.3390/atmos10090521","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072258601&doi=10.3390%2fatmos10090521&partnerID=40&md5=3dbdb39d465e4e22b5450f9b9be609e8","A methodology is presented to evaluate the accuracy of cloud cover fraction (CCf) forecasts generated by numerical weather prediction (NWP) and climate models. It is demonstrated with a case study consisting of simulations from theWeather Research and Forecasting (WRF) model. In this study, since the WRF CCf forecasts were initialized with reanalysis fields from the North American Mesoscale (NAM) Forecast System, the characteristics of the NAM CCf products were also evaluated. The procedures relied extensively upon manually-generated, binary cloud masks created from VIIRS (Visible Infrared Imager Radiometry Suite) imagery, which were subsequently converted into CCf truth at the resolution of the NAM and WRF gridded data. The initial results from the case study revealed biases toward under-clouding in the NAM CCf analyses and biases toward over-clouding in the WRF CCf products. These biases were evident in images created from the gridded NWP products when compared to VIIRS imagery and CCf truth data. Thus, additional simulations were completed to help assess the internal procedures used in the WRF model to translate moisture forecast fields into layered CCf products. Two additional sets of WRF CCf 24 h forecasts were generated for the region of interest using WRF restart files. One restart file was updated with CCf truth data and another was not changed. Over-clouded areas in the updated WRF restart file that were reduced with an update of the CCf truth data became over-clouded again in the WRF 24 h forecast, and were nearly identical to those from the unchanged restart file. It was concluded that the conversion of WRF forecast fields into layers of CCf products deserves closer examination in a future study. © 2019 by the authors."
"55574869900;57190534239;56898396100;","Four-year ground-based observations of the aerosol effects on cloud base height in Wuhan, China",2019,"10.1016/j.apr.2019.05.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068883703&doi=10.1016%2fj.apr.2019.05.001&partnerID=40&md5=b80bbf84309aae15c99a74e171791153","Aerosols can modify cloud properties by affecting the concentration and size of cloud droplets and the strength of cloud convection. Understanding the effects of aerosol on cloud remains challenging because of the different effects of aerosol on various conditions and regions. In this study, we survey the effect of aerosol on cloud base height (CBH) through four-year ground-based observations in Wuhan, China. A robust positive correlation between aerosol loading and CBH can be found via annual and correlation analyses, which suggest the systematic invigoration of clouds through aerosol loading. The statistical analysis of collocated measurements of PM10 concentrations, meteorological factors, and CBHs suggest that temperature, relative humidity and aerosol particles collectively influence CBH variations. The present finding also demonstrate that the influence of aerosol particles on promoting CBH is prominent under the conditions of relatively high humidity and low temperature. This study provides a new perspective for understanding the response of aerosol-cloud interactions in an urban area, which will play important roles in regional climate change and human life. © 2019"
"57208682797;17346212400;23967911100;8213763800;36812255500;7003880283;","Theoretical study of aerosol particle electroscavenging by clouds",2019,"10.1016/j.jaerosci.2019.04.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065542828&doi=10.1016%2fj.jaerosci.2019.04.001&partnerID=40&md5=220ac489f0e659fc3a84b17d61d129a5","This paper describes a theoretical model which computes the collection efficiency of aerosol particles by droplets, due to the combined action of dynamic (inertia, weight and drag)and electrophoresis forces acting on an aerosol particle of radius 0.004≤a≤1.3μm around a droplet of radius 15≤A≤100μm. The electrostatic forces are defined following the concept of image charges. In the given particle range, the Brownian motion must be considered and was consequently added to the model. A novel approach is developed, based on the Langevin's theory and solved using an Itô process. Results of electroscavenging related to natural atmospheric ionisation, as well as for strongly charged aerosol particles released after a nuclear accident, are presented with pressure and temperature representative of the mid-troposphere (-17°C, 540 hPa). The droplet charges considered in the paper are representative of weakly and strongly electrified clouds. The values of collection efficiency computed are convenient for incorporation into cloud models and to study scavenging of aerosol particles by clouds whether for climate, pollution or nuclear safety issues. © 2019 The Authors"
"16644246500;7003648299;7102567936;57204886915;22954298000;35372180500;36992744000;7006354215;55388694300;36179077700;55286185400;","Moist static energy budget analysis of tropical cyclone intensification in high-resolution climate models",2019,"10.1175/JCLI-D-18-0599.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070738248&doi=10.1175%2fJCLI-D-18-0599.1&partnerID=40&md5=87c41def7367930ee0f7f8df519f0255","Tropical cyclone intensification processes are explored in six high-resolution climate models. The analysis framework employs process-oriented diagnostics that focus on how convection, moisture, clouds, and related processes are coupled. These diagnostics include budgets of column moist static energy and the spatial variance of column moist static energy, where the column integral is performed between fixed pressure levels. The latter allows for the quantification of the different feedback processes responsible for the amplification of moist static energy anomalies associated with the organization of convection and cyclone spinup, including surface flux feedbacks and cloud-radiative feedbacks. Tropical cyclones (TCs) are tracked in the climate model simulations and the analysis is applied along the individual tracks and composited over many TCs. Two methods of compositing are employed: a composite over all TC snapshots in a given intensity range, and a composite over all TC snapshots at the same stage in the TC life cycle (same time relative to the time of lifetime maximum intensity for each storm). The radiative feedback contributes to TC development in all models, especially in storms of weaker intensity or earlier stages of development. Notably, the surface flux feedback is stronger in models that simulate more intense TCs. This indicates that the representation of the interaction between spatially varying surface fluxes and the developing TC is responsible for at least part of the intermodel spread in TC simulation. © 2019 American Meteorological Society."
"7102175039;7402598670;11241850900;23978908300;55342411300;7003483600;26643440200;6508343844;6506553716;57169556000;7102351461;7006935485;57211627348;6505906590;6504785410;57211628816;","A high-resolution 1983–2016 TMAX climate data record based on infrared temperatures and stations by the climate hazard center",2019,"10.1175/JCLI-D-18-0698.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073450766&doi=10.1175%2fJCLI-D-18-0698.1&partnerID=40&md5=3cca7d368405d6a77ba1f6c2fda1294d","Understanding the dynamics and physics of climate extremes will be a critical challenge for twenty-first-century climate science. Increasing temperatures and saturation vapor pressures may exacerbate heat waves, droughts, and precipitation extremes. Yet our ability to monitor temperature variations is limited and declining. Between 1983 and 2016, the number of observations in the University of East Anglia Climatic Research Unit (CRU) Tmax product declined precipitously (5900 / 1000); 1000 poorly distributed measurements are insufficient to resolve regional Tmax variations. Here, we show that combining long (1983 to the near present), high-resolution (0.058), cloud-screened archives of geostationary satellite thermal infrared (TIR) observations with a dense set of;15 000 station observations explains 23%, 40%, 30%, 41%, and 1% more variance than the CRU globally and for South America, Africa, India, and areas north of 508N, respectively; even greater levels of improvement are shown for the 2011–16 period (28%, 45%, 39%, 52%, and 28%, respectively). Described here for the first time, the TIR Tmax algorithm uses subdaily TIR distributions to screen out cloud-contaminated observations, providing accurate (correlation'0.8) gridded emission Tmax estimates. Blending these gridded fields with;15 000 station observations provides a seamless, high-resolution source of accurate Tmax estimates that performs well in areas lacking dense in situ observations and even better where in situ observations are available. Cross-validation results indicate that the satellite-only, station-only, and combined products all perform accurately (R' 0.8–0.9, mean absolute errors' 0.8–1.0). Hence, the Climate Hazards Center Infrared Temperature with Stations (CHIRTSmax) dataset should provide a valuable resource for climate change studies, climate extreme analyses, and early warning applications. © 2019 American Meteorological Society."
"55814531500;55613785200;56463154100;","Sensitivity of summer precipitation in regional spectral model simulations over eastern China to physical schemes: Daily, extreme and diurnal cycle",2019,"10.1002/joc.6077","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065011145&doi=10.1002%2fjoc.6077&partnerID=40&md5=1872aa45db50cfdc28c84785d807bf1e","In this study, the capability of the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) in reproducing the precipitation in eastern China is evaluated with the simulation of 25-year (1983–2007) summertime climate driven by the NCEP-Department of Energy reanalysis. The impacts of different physical schemes on daily precipitation, diurnal cycle and precipitation extremes are studied through detailed analyses. The results show that the RSM model can reproduce the precipitation characteristics over eastern China, and the results are sensitive to the internal model physics and spectral nudging method. The cloud water prediction scheme of CLD3 (CLDn, the cloud schemes, classified according to the complexity microphysical processes) and the modified version of the Kain-Fritsch scheme (KF2) tend to overestimate the summer precipitation by reproducing higher humidity, while the CLD1 and the Relaxed Arakawa Schubert scheme (RAS) always underestimate it. It is also demonstrated that RSM has the capability to reproduce the spatial distributions of the extreme precipitation intensity and duration. The physical schemes have great impact on the simulations of extreme precipitation over eastern China, especially on regional scales. For the diurnal cycle of precipitation, the responses of the simulated amplitude to the physical schemes differ with regions. The RAS scheme underestimates the amplitudes over southeastern China, while the KF2 generates positive biases. The involving of the scale selective bias correction (SSBC) method can properly improve the simulated mean precipitation and diurnal cycle of summer precipitation. However, it shows lower skill in improving extreme precipitation indices over eastern China, especially in the experiments with CLD3 scheme. In summary, the selection of CLD1 and KF2 scheme, involving SSBC method performs better than the other experiments. © 2019 Royal Meteorological Society"
"57214683754;55738957800;","Relating convection to GCM grid-scale fields using cloud-resolving model simulation of a squall line observed during MC3E field experiment",2019,"10.3390/atmos10090523","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072257221&doi=10.3390%2fatmos10090523&partnerID=40&md5=fb08c3962c0064bdb9b61733a4b24523","In this study, a WRF (Weather Research and Forecasting) model is used as a cloud-resolving model to simulate a squall line observed on 20 May 2011 in the Southern Great Plains (SGP) of the United States. The model output is then used to examine the relationships between convective precipitation and coarse-grained variables averaged over a range of subdomain sizes equivalent to various global climate model horizontal resolutions. The objective is to determine to what extent convection within the subdomains can be related to these ""large-scale"" variables, thus that they can potentially serve as closure in convective parameterization. Results show that convective precipitation is well correlated with the vertical velocity at 500 hPa, column integrated moisture convergence and CAPE change due to large-scale advective forcing (dCAPE) for various subdomain sizes, but the correlation decreases with decreasing subdomain size. dCAPE leads convective precipitation for all subdomain sizes examined; however, the lead time decreases with decreasing subdomain size. Moisture convergence leads convective precipitation for subdomain sizes greater than 32 km but has no lead time for smaller subdomain sizes. Mid-tropospheric vertical velocity has no lead time or slightly lags convective precipitation. The lead/lag composite analysis with respect to maximum precipitation time indicates that peaks of large-scale variables increase with decreasing subdomain size. The peaks of 500 hPa vertical velocity and column integrated moisture convergence occur at the same time as maximum precipitation, but maximum dCAPE leads maximum precipitation by twelve minutes. © 2019 by the authors."
"57206291320;7006399110;36026612000;57206332144;8891521600;6701363458;","Spectral Signature of the Biosphere: NISTAR Finds It in Our Solar System From the Lagrangian L-1 Point",2019,"10.1029/2019GL083736","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074080180&doi=10.1029%2f2019GL083736&partnerID=40&md5=244c0113a8fb35748572c4f30c899524","NISTAR, aboard the DSCOVR spacecraft, is one of the National Aeronautics and Space Administration's energy budget instruments designed to measure the seasonal changes in Earth's total outgoing radiation from a unique vantage point at the Lagrangian L-1 point a million miles from Earth. Global radiation energy balance measurements are important constraints for climate models, but are difficult measurements to quantify. CERES data offer the best current observational constraints, but need extensive modeling to get global energy. NISTAR observes the entire dayside hemisphere of the Earth as a single pixel, splitting the shortwave radiation into broadband visible and near-infrared components (analogous to the narrowband spectral ratios used to define vegetation indices). This spectral partitioning at the 0.7-μm vegetation red edge offers unique constraints on climate model spectral treatment of cloud and surface albedos. Moreover, NISTAR's unique viewing geometry amounts to observing the Earth as an exoplanet, which opens a new perspective on exoplanet observations. ©2019. American Geophysical Union. All Rights Reserved."
"57197840302;7005557215;14036628000;","Separating the impact of individual land surface properties on the terrestrial surface energy budget in both the coupled and uncoupled land–atmosphere system",2019,"10.1175/JCLI-D-18-0812.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074786282&doi=10.1175%2fJCLI-D-18-0812.1&partnerID=40&md5=adda6d77936bf1d7d11046e81b3e521a","Changes in the land surface can drive large responses in the atmosphere on local, regional, and global scales. Surface properties control the partitioning of energy within the surface energy budget to fluxes of shortwave and longwave radiation, sensible and latent heat, and ground heat storage. Changes in surface energy fluxes can impact the atmosphere across scales through changes in temperature, cloud cover, and large-scale atmospheric circulation. We test the sensitivity of the atmosphere to global changes in three land surface properties: albedo, evaporative resistance, and surface roughness. We show the impact of changing these surface properties differs drastically between simulations run with an offline land model, compared to coupled land–atmosphere simulations that allow for atmospheric feedbacks associated with land–atmosphere coupling. Atmospheric feedbacks play a critical role in defining the temperature response to changes in albedo and evaporative resistance, particularly in the extratropics. More than 50% of the surface temperature response to changing albedo comes from atmospheric feedbacks in over 80% of land areas. In some regions, cloud feedbacks in response to increased evaporative resistance result in nearly 1 K of additional surface warming. In contrast, the magnitude of surface temperature responses to changes in vegetation height are comparable between offline and coupled simulations. We improve our fundamental understanding of how and why changes in vegetation cover drive responses in the atmosphere, and develop understanding of the role of individual land surface properties in controlling climate across spatial scales—critical to understanding the effects of land-use change on Earth’s climate. © 2019 American Meteorological Society."
"56419378200;57209534447;57014884300;9133797900;6603585811;","Modelling the possible impacts of climate change on the thermal regime and macroinvertebrate species of a regulated prairie river",2019,"10.1002/eco.2102","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068042538&doi=10.1002%2feco.2102&partnerID=40&md5=cac35dcd18c05586f4d2632d38f4954d","The thermal regime is a key consideration for instream flow management as the ecological integrity of river ecosystems relies on the natural dynamics of temperature range and spatiotemporal characteristics. Climate change can alter thermal regimes and influence water temperatures. This study aims to investigate probable impacts of climate change (predicted changes in meteorological forcing variables) on the thermal regime and macroinvertebrate species of a regulated prairie river. A 2D laterally averaged CE-QUAL-W2 hydrodynamic thermal lake model for Lake Diefenbaker was coupled with a Water Quality Analysis Simulation Program Version 7 (WASP7) river temperature model and applied to the lower South Saskatchewan River in Canada. Three decades, 2001–2010, 2041–2050, and 2081–2090, were modelled using atmospheric forcing data (relative humidity, dew point, daily mean near-surface wind velocity, near-surface air temperature, total cloud fraction, and surface air pressure) from the Canadian Centre for Climate Modelling and Analysis experiments (CORDEX). To estimate future climate change impacts on the resident macroinvertebrate species, the known temperature tolerances of various macroinvertebrate species were compared with modelled temperature regimes. The WASP model calibration (2011–2012) and validation (2013) outputs produced an acceptable visual fit, whereby predicted values overlap sampled values, to observed water temperatures at Clarkboro and Muskoday sample sites. Major effects on the thermal regime were simulated due to the increase in water temperature induced by Gardiner Dam, which in turn indicated a possible effect on macroinvertebrate species. Gardiner Dam was also shown to be highly sensitive to inflow variations as well as to temperature changes. These findings contribute to the understanding of how future climate-induced river water temperature changes may influence macroinvertebrate species in temperate river systems. This valuable information can inform further laboratory studies of temperature impacts on current macroinvertebrate communities and the development of future mitigation strategies. © 2019 John Wiley & Sons, Ltd."
"57188931669;57191168465;6701753955;24764521300;","Bimodal climate control of shoreline change influenced by Interdecadal Pacific Oscillation variability along the Cooloola Sand Mass, Queensland, Australia",2019,"10.1016/j.margeo.2019.105971","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067873728&doi=10.1016%2fj.margeo.2019.105971&partnerID=40&md5=c4c6c951451923ea8d6d1adc3df36235","Wave climate in southeast Queensland, Australia has been correlated to changes in the Southern Oscillation Index (SOI), but observations of shoreline change associated with the variable wave climate have been limited due to a paucity of aerial photography, LiDAR, and other beach profiling datasets in this region. A multi-decadal, sub-annual temporal resolution shoreline dataset spanning 1996 to 2017 was produced using satellite imagery collected by Landsat 5, 7, and 8. A total of 147 shoreline positions were delineated using the Modified Normalized Difference Water Index on cloud-free imagery and corrected for horizontal offsets forced by variable tide stages at the satellite flyover time. The relative influence of SOI, the Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO), and Subtropical Ridge Latitude (STR-L) and Pressure (STR-P) on shoreline dynamics along the Cooloola Sand Mass in Queensland are assessed by performing cross correlations between their respective index values and shoreline change distances calculated by the Digital Shoreline Analysis System. A bimodal climate control of shoreline change is observed dependent upon the phase of the Interdecadal Pacific Oscillation (IPO). IPO modulates the impacts of ENSO on eastern Australia through its control over the position of the South Pacific Convergence Zone and elevating/lowering of tropical Pacific sea surface temperatures. During negative IPO, SOI is negatively correlated to the Cooloola Sand Mass shoreline indicating that the shoreline retreats during negative SOI phases. During positive IPO, the impacts of SOI are weakened and the STR becomes the primary driver of shoreline change with shoreline response being contingent upon its orientation. The SW-NE aligned Noosa North shoreline erodes in response to poleward movement of the STR, likely due to the enhanced cross-shore wave attack as a result of anti-clockwise wave rotation. The opposite response is shown at the SE-NW aligned Rainbow Beach shoreline, which is oriented almost parallel to the incident wave direction and is sheltered by the Double Island Point headland. These results suggest that climate control on shoreline change at Cooloola Sand Mass, and likely other sand islands in the region, is two-tiered, whereby interdecadal variability of the IPO governs the relative influence of SOI and STR under the different IPO phases. The linked climate and shoreline variability correlation shown in this study provides significant insight into how the Cooloola Sand Mass shoreline will respond to future climate changes under a global warming scenario. © 2019 Elsevier B.V."
"57191596089;55944765000;57202949614;57212936311;7404829395;8505418900;7006970286;7005973015;","Earth as an Exoplanet: A Two-dimensional Alien Map",2019,"10.3847/2041-8213/ab3a49","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072560065&doi=10.3847%2f2041-8213%2fab3a49&partnerID=40&md5=dcf076d0ca0ba2ef24f0daebaf93220f","Resolving spatially varying exoplanet features from single-point light curves is essential for determining whether Earth-like worlds harbor geological features and/or climate systems that influence habitability. To evaluate the feasibility and requirements of this spatial-feature resolving problem, we present an analysis of multi-wavelength single-point light curves of Earth, where it plays the role of a proxy exoplanet. Here, ∼10,000 Deep Space Climate Observatory/Earth Polychromatic Imaging Camera frames collected over a two-year period were integrated over the Earth's disk to yield a spectrally dependent point source and analyzed using singular value decomposition. We found that, between the two dominant principal components (PCs), the second PC contains surface-related features of the planet, while the first PC mainly includes cloud information. We present the first two-dimensional (2D) surface map of Earth reconstructed from light curve observations without any assumptions of its spectral properties. This study serves as a baseline for reconstructing the surface features of Earth-like exoplanets in the future. © 2019. The American Astronomical Society. All rights reserved.."
"57209089820;57219122737;25121889100;","Modeling the hydroclimatic effects of local land use and land cover changes on the water budget in the upper Euphrates – Tigris basin",2019,"10.1016/j.jhydrol.2019.06.074","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063001856&doi=10.1016%2fj.jhydrol.2019.06.074&partnerID=40&md5=b035362114ef5d6da196994441a3f214","The waters of the Euphrates and Tigris rivers have always been a vital resource in the water-food-energy nexus of the Middle East region. The currently ongoing Southeastern Anatolia Project (GAP) in Turkey aims to increase regional prosperity by optimizing the use of these waters for irrigation and hydropower. Since the beginning of the 1990s, the irrigation schemes and water management infrastructures within the scope of the GAP have caused significant land use and land cover (LULC) change in this semi-arid region. We employed a high resolution regional climate model to simulate the effects of irrigation induced LULC changes on the regional water and energy balances. For this purpose, historical simulations were conducted by using three land cover distributions which reflect the increase in irrigation and water surfaces. Our experiment reveals that water loss through evapotranspiration increases significantly with the areal expansion of irrigation. This increase is driven by the change in partitioning of the available energy at the surface between turbulent heat fluxes. On the one hand, a significant reduction in sensible heat flux causes local cooling by around 0.4 °C and 0.8 °C for the current and future irrigation conditions, respectively. On the other hand, the increase in latent heat flux enhances evapotranspiration and consequently atmospheric water vapor concentration. The moistening of a shallower boundary layer triggers the formation of convective clouds, which increases convective precipitation, most notably during the irrigation months. The enhanced water loss through evapotranspiration has potential to significantly alter the water budget of the GAP region. It seems that the water surplus of the headwaters region may not be enough to meet the water deficit of the GAP region in the future if the planned irrigation schemes are carried out to completion. © 2019 Elsevier B.V."
"57202816902;57200293605;24075260300;7003590587;26643937400;6602509707;57209533457;57053040000;35925570700;36025877000;57209529512;55502832100;36186687300;","Statistical modelling of spatial patterns of the urban heat island intensity in the urban environment of Augsburg, Germany",2019,"10.1016/j.uclim.2019.100491","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068057004&doi=10.1016%2fj.uclim.2019.100491&partnerID=40&md5=909a98ef624227f968740ec964aef8a4","Spatial and temporal variability of meteorological variables across urban areas due to differences in land surface characteristics is a common phenomenon. Most pronounced is the effect of land cover on air temperature. In this study, parametric and non-parametric statistical approaches (stepwise multiple linear regression, random forests) were applied in order to model sub-daily and daily spatial patterns of the urban heat island intensity in the major city of Augsburg, Southern Germany, and its rural surroundings. A large number of model setups utilizing variables from different land surface data sets as predictors and taking into account different seasonal, daily and meteorological situations was examined. The results were compared concerning different measures of model performance (mean squared skill score, mean squared error, explained variance). For individual setups and situations considerable skill with a mean squared skill score of up to 0.85 was reached. The best performing models were obtained from multiple linear regression for situations with low wind speeds and cloud cover in the morning and evening. Selected models were utilized to derive continuous spatial distributions of the air temperature deviations from a rural reference station. The resulting maps can be useful for various applications, e.g. in the context of urban planning. © 2019 Elsevier B.V."
"25823096700;7201869936;6701449374;","Assessing the scaling of the tree branch diameters frequency distribution with terrestrial laser scanning: methodological framework and issues",2019,"10.1007/s13595-019-0854-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067990213&doi=10.1007%2fs13595-019-0854-7&partnerID=40&md5=4cb637ca8b4c5587f823f5e7ceabdf7d","Key message: This article presents a specific methodology for assessing the scaling of the frequency distribution of the branch diameters within a tree from terrestrial laser scanning (TLS), using large oak trees (Quercus petraea(Matt.) Liebl.) as the case study. It emphasizes the potential of TLS in assessing branch scaling exponents and provides new insights in forest ecology and biomass allometric modelling. Context: Many theoretical works invoke the scaling allometry of the frequency distribution of the branch diameters in tree form analyses, but testing such an allometry requires a huge amount of data that is particularly difficult to obtain from traditional measurements. Aims: The aims of this study were (i) to clarify the theoretical and methodological basics of this allometry, (ii) to explore the possibility of establishing this allometry from terrestrial laser scanning (TLS) and geometric modelling for the solid wood structure (i.e. diameters > 7 cm) of large trees, and (iii) to highlight the major methodological issues. Methods: Three large oak trees (Quercus petraea (Matt.) Liebl.) were digitized in leaf-off conditions from multiple points of view in order to produce accurate three-dimensional point clouds. Their woody structure was modelled using geometric procedures based on polyline and cylinder fitting. The allometry was established using basics found in literature: regular sampling of branch diameters and consideration of the living branches only. The impact of including the unpruned dead branches in the allometry was assessed, as well as the impact of modelling errors for the largest branch diameter classes. Results: TLS and geometric modelling revealed a scaling exponent of − 2.4 for the frequency distribution of the branch diameters for the solid wood structure of the trees. The dead branches could highly influence the slope of the allometry, making essential their detection in TLS data. The accuracy of diameter measurement for the highest diameter classes required particular attention, slight errors in these classes having a high influence on the slope of the allometry. Conclusion: These results could make it possible automated programs to process large numbers of trees and, therefore, to provide new insights in assessing forest structure, scaling, and dynamics for various environments in the context of climate change. © 2019, INRA and Springer-Verlag France SAS, part of Springer Nature."
"57203568101;7405728922;57188963864;56397302900;57201262592;57209423805;57214360459;24312055100;54413425200;35794562900;6701562113;7004242155;7102084129;57196499374;","High-altitude and long-range transport of aerosols causing regional severe haze during extreme dust storms explains why afforestation does not prevent storms",2019,"10.1007/s10311-019-00858-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063068289&doi=10.1007%2fs10311-019-00858-0&partnerID=40&md5=6ed74023c31e38e560a6f1f45a0ce719","Climate change is predicted to induce more extreme events such as storms, heat waves, drought and floods. Dust storms are frequently occurring in northern China. Those storms degrade air quality by decreasing visibility and inducing cardiovascular and respiratory diseases. To control dust storms, the Chinese government has launched a large-scale afforestation program by planting trees in arid areas, but the effectiveness of this program is still uncertain because the trajectories and altitudes of dust transport are poorly known. In particular, afforestation would be effective only if dust transport occurs at low altitudes. To test this hypothesis, we analyzed the extreme dust storm from May 2 to 7, 2017, which resulted in record-breaking dust loads over northern China. For that, we used dust RGB-composite data from the Himawari-8 satellite and the cloud-aerosol lidar, moderate-resolution imaging spectroradiometer data, and surface monitoring data. The source regions of the dust storms were identified using the hybrid single-particle Lagrangian integrated trajectory model and infrared pathfinder satellite observation. Contrary to our hypothesis, results show that dust is transported at high altitude of 1.0–6.5 km over long distances from northwestern China. This finding explains why the afforestation has not been effective to prevent this storm. Results also disclose the highest particulate matter (PM) concentrations of 447.3 μg/m3 for PM2.5 and 1842.0 μg/m3 for PM10 during the dust storm. Those levels highly exceed Chinese ambient air quality standards of 75 μg/m3 for PM2.5 and 150 μg/m3 for PM10. © 2019, Springer Nature Switzerland AG."
"34977912100;7201799893;16309079300;8306186800;56377384400;7004294279;6701432187;54790196200;57203103268;7102286699;15725353500;7103123474;15049811600;53984204700;57203104329;6603060770;35270219700;57198946531;57195634721;6701525958;26666059700;36118126800;37000037400;7005728210;7102521078;57204786518;35109636800;","Constraining exoplanet metallicities and aerosols with the contribution to ARIEL spectroscopy of exoplanets (CASE)",2019,"10.1088/1538-3873/ab2d54","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073521832&doi=10.1088%2f1538-3873%2fab2d54&partnerID=40&md5=41cbb8082cfe4305f955180795b3a448","Launching in 2028, ESA’s 0.64 m2 Atmospheric Remote-sensing Exoplanet Large-survey (ARIEL) survey of ∼1000 transiting exoplanets will build on the legacies of NASA’s Kepler and Transiting Exoplanet Survey Satellite (TESS), and complement the James Webb Space Telescope (JWST) by placing its high-precision exoplanet observations into a large, statistically significant planetary population context. With continuous 0.5–7.8 μm coverage from both FGS (0.5–0.6, 0.6–0.81, and 0.81–1.1 μm photometry; 1.1–1.95 μm spectroscopy) and AIRS (1.95–7.80 μm spectroscopy), ARIEL will determine atmospheric compositions and probe planetary formation histories during its 3.5 yr mission. NASA’s proposed Contribution to ARIEL Spectroscopy of Exoplanets (CASE) would be a subsystem of ARIEL’s Fine Guidance Sensor (FGS) instrument consisting of two visible-to-infrared detectors, associated readout electronics, and thermal control hardware. FGS, to be built by the Polish Academy of Sciences Space Research Centre, will provide both fine guiding and visible to near-infrared photometry and spectroscopy, providing powerful diagnostics of atmospheric aerosol contribution and planetary albedo, which play a crucial role in establishing planetary energy balance. The CASE team presents here an independent study of the capabilities of ARIEL to measure exoplanetary metallicities, which probe the conditions of planet formation, and FGS to measure scattering spectral slopes, which indicate if an exoplanet has atmospheric aerosols (clouds and hazes), and geometric albedos, which help establish planetary climate. Our simulations assume that ARIEL’s performance will be 1.3×the photon-noise limit. This value is motivated by current transiting exoplanet observations: Spitzer/IRAC and Hubble/WFC3 have empirically achieved 1.15×the photon-noise limit. One could expect similar performance from ARIEL, JWST, and other proposed future missions such as HabEx, LUVOIR, and Origins. Our design reference mission simulations show that ARIEL could measure the mass– metallicity relationship of its 1000-planet single-visit sample to >7.5σ and that FGS could distinguish between clear, cloudy, and hazy skies and constrain an exoplanet’s atmospheric aerosol composition to ≳5σ for hundreds of targets, providing statistically transformative science for exoplanet atmospheres. © 2019. The Astronomical Society of the Pacific."
"57211093663;37029434200;57014496500;8924236800;57207460803;57207976114;","Large scale agricultural plastic mulch detecting and monitoring with multi-source remote sensing data: A case study in Xinjiang, China",2019,"10.3390/rs11182088","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072642056&doi=10.3390%2frs11182088&partnerID=40&md5=8fa837cb59654340159abe61091275af","Plastic mulching has been widely practiced in crop cultivation worldwide due to its potential to significantly increase crop production. However, it also has a great impact on the regional climate and ecological environment. More importantly, it often leads to unexpected soil pollution due to fine plastic residuals. Therefore, accurately and timely monitoring of the temporal and spatial distribution of plastic mulch practice in large areas is of great interest to assess its impacts. However, existing plastic-mulched farmland (PMF) detecting efforts are limited to either small areas with high-resolution images or coarse resolution images of large areas. In this study, we examined the potential of cloud computing and multi-temporal, multi-sensor satellite images for detecting PMF in large areas. We first built the plastic-mulched farmland mapping algorithm (PFMA) rules through analyzing its spectral, temporal, and auxiliary features in remote sensing imagery with the classification and regression tree (CART).We then applied the PFMA in the dry region of Xinjiang, China, where a water resource is very scarce and thus plastic mulch has been intensively used and its usage is expected to increase significantly in the near future. The experimental results demonstrated that the PFMA reached an overall accuracy of 92.2% with a producer's accuracy of 97.6% and a user's accuracy of 86.7%, and the F-score was 0.914 for the PMF class. We further monitored and analyzed the dynamics of plastic mulch practiced in Xinjiang by applying the PFMA to the years 2000, 2005, 2010, and 2015. The general pattern of plastic mulch usage dynamic in Xinjiang during the period from 2000 to 2015 was well captured by our multi-temporal analysis. © 2019 by the authors."
"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."
"56270311300;","Aerosol radiative effects with MACv2",2019,"10.5194/acp-19-10919-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071636614&doi=10.5194%2facp-19-10919-2019&partnerID=40&md5=0c1323d0d0c80ff155595bdda06bd863","Monthly global maps for aerosol properties of the Max Planck Aerosol Climatology version 2 (MACv2) are applied in an offline radiative transfer model to determine aerosol radiative effects. This model setup cannot address rapid adjustments by clouds, but current evidence suggests their contribution to be small when compared to the instantaneous radiative forcing. Global maps are presented to detail the regional and seasonal variability associated with (annual) global averages. Radiative effects caused by the aerosol presence (direct effects) and by aerosol modified clouds (indirect effects) are examined. Direct effects are determined for total aerosol, anthropogenic aerosol and extracted individual aerosol components. Indirect effects cover the impact of reduced cloud drop sizes by anthropogenic aerosol. Present-day global annual radiative effects for anthropogenic aerosol yield (1) a climate cooling of -1:0Wm-2 at the top of the atmosphere (TOA); (2) a surface net-flux reduction of -2:1Wm-2; and, by difference; (3) an atmospheric effect of C1.1Wm-2. This atmospheric solar heating is almost entirely a direct effect. On a global basis, indirect effects (-0:65Wm-2) dominate direct effects (-0:35Wm-2) for the present-day climate response at the TOA, whereas the present-day surface radiative budget is more strongly reduced by direct effects (-1:45Wm-2) than by indirect effects (-0:65Wm-2). Natural aerosols are on average less absorbing and larger in size. However, their stronger solar TOA cooling efficiency is offset by a non-negligible infrared (IR) greenhouse warming efficiency. In the sum the global average annual direct forcing efficiencies (per unit AOD) for natural and anthropogenic aerosol are similar: -12Wm-2 per unit AOD for all-sky conditions and -24Wm-2 per unit AOD for clearsky conditions. The present-day direct TOA impact by all soot (BC) is C0:55Wm-2, when globally and annually averaged. Between C0:25 and C0:45Wm-2 of that can be attributed to anthropogenic sources, depending on assumptions for the preindustrial BC reference state. Similarly, the preindustrial fine-mode reference uncertainty has a strong influence not just on the direct effect but even more on the indirect effect. Present-day aerosol TOA forcing is estimated to stay within the -0:7 to -1:6Wm-2 range (with the best estimate at -1:0Wm-2). Calculations with scaled temporal changes to anthropogenic AOD from global modeling indicate that the global annual aerosol forcing has not changed much over the last decades, despite strong shifts in regional maxima for anthropogenic AOD. These regional shifts explain most solar insolation (brightening or dimming) trends that have been observed by ground-based radiation data. © Author(s) 2019."
"57209465284;8550791300;57214160655;7006595513;55332349200;22979686100;25630924500;57210820806;57189006448;6601927317;7006415284;","Characterization of aerosol properties at Cyprus, focusing on cloud condensation nuclei and ice-nucleating particles",2019,"10.5194/acp-19-10883-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071559225&doi=10.5194%2facp-19-10883-2019&partnerID=40&md5=29e8a24d48a5738d708e4895f865b100","As part of the A-LIFE (Absorbing aerosol layers in a changing climate: aging, LIFEtime and dynamics) campaign, ground-based measurements were carried out in Paphos, Cyprus, to characterize the abundance, properties, and sources of aerosol particles in general and cloud condensation nuclei (CCN) and ice-nucleating particles (INP) in particular. New particle formation (NPF) events with subsequent growth of the particles into the CCN size range were observed. Aitken mode particles featured k values of 0.21 to 0.29, indicating the presence of organic materials. Accumulation mode particles featured a higher hygroscopicity parameter, with a median k value of 0.57, suggesting the presence of sulfate and maybe sea salt particles mixed with organic carbon. A clear downward trend of k with increasing supersaturation and decreasing dcrit was found. Super-micron particles originated mainly from sea-spray aerosol (SSA) and partly from mineral dust. INP concentrations (NINP) were measured in the temperature range from-6:5 to-26:5 °C, using two freezing array-type instruments. NINP at a particular temperature span around 1 order of magnitude below-20 °C and about 2 orders of magnitude at warmer temperatures (T >-18 °C). Few samples showed elevated concentrations at temperatures >-15 °C, which suggests a significant contribution of biological particles to the INP population, which possibly could originate from Cyprus. Both measured temperature spectra and NINP probability density functions (PDFs) indicate that the observed INP (ice active in the temperature range between-15 and-20 °C) mainly originate from long-range transport. There was no correlation between NINP and particle number concentration in the size range> 500 nm (N>500 nm). Parameterizations based on N>500 nm were found to overestimate NINP by about 1 to 2 orders of magnitude. There was also no correlation between NINP and particle surface area concentration. The ice active surface site density (ns) for the polluted aerosol encountered in the eastern Mediterranean in this study is about 1 to 3 orders of magnitude lower than the ns found for dust aerosol particles in previous studies. This suggests that observed NINP PDFs such as those derived here could be a better choice for modeling NINP if the aerosol particle composition is unknown or uncertain. © Author(s) 2019."
"55531609200;56537463000;57200702127;55802732200;7404829395;7006417494;","Relationships Between Tropical Ascent and High Cloud Fraction Changes With Warming Revealed by Perturbation Physics Experiments in CAM5",2019,"10.1029/2019GL083026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071317038&doi=10.1029%2f2019GL083026&partnerID=40&md5=cb8cc659cdaacddb5843cd33aa0952a7","Tropical ascent area (Aa) and high cloud fraction (HCF) are projected to decrease with surface warming in most Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Perturbing deep convective parameters in the Community Atmosphere Model (CAM5) results in a similar spread and correlation between HCF and Aa responses to interannual warming compared to the CMIP5 ensemble, with a narrower Aa corresponding to greater HCF reduction. Perturbing cloud physics parameters produces a comparatively smaller range of Aa responses to warming and a dissimilar HCF-Aa relation to that in CMIP5; a narrower Aa corresponds to less HCF reduction, likely due to cloud radiative effects. A narrowing of Aa corresponds to a regime shift toward stronger precipitation in both experiments. We infer that model differences in deep convection parameterization likely play a greater role than differing cloud physics in determining the diverse responses of Aa and HCF to warming in CMIP5. © 2019. American Geophysical Union. All Rights Reserved."
"56044817200;6701853567;36179218000;26643043700;36767412900;7006591842;","Contributions of aerosol-cloud interactions to mid-Piacenzian seasonally sea ice-free Arctic Ocean",2019,"10.1029/2019GL083960","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071318750&doi=10.1029%2f2019GL083960&partnerID=40&md5=a759d464372f64227a954a05f46dcad2","Forcings and feedbacks controlling the seasonally sea ice-free Arctic Ocean during the mid-Piacenzian Warm period (3.264–3.025 Ma, MPWP), a period when CO2 level, geography, and topography were similar to present day, remain unclear given that many complex Earth System Models with comparatively higher skills at simulating twentieth century Arctic sea ice tend to produce perennial Arctic sea ice for this period. We demonstrate that explicitly simulating aerosol-cloud interactions and the exclusion of industrial pollutants from model forcing conditions is key to simulating seasonally sea ice-free Arctic Ocean of MPWP. The absence of industrial pollutants leads to fewer and larger cloud droplets over the high-latitude Northern Europe and North Pacific, which allows greater absorption of solar radiation at the surface during the early summer. This enhanced absorption triggers the seasonally runaway sea ice surface albedo feedback that gives rise to September sea ice-free Arctic Ocean and strongly amplified northern high-latitude surface warmth. ©2019. American Geophysical Union. All Rights Reserved."
"6506539438;","Observational Evidence for Two Modes of Coupling Between Sea Surface Temperatures, Tropospheric Temperature Profile, and Shortwave Cloud Radiative Effect in the Tropics",2019,"10.1029/2019GL083990","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071223832&doi=10.1029%2f2019GL083990&partnerID=40&md5=a578593c32a4651ab6ef5a4e8dda84f0","Tropical average shortwave cloud radiative effect (SWCRE) anomalies observed by CERES/EBAF v4 are explained by observed average sea surface temperature ((Formula presented.)) and the difference between the warmest 30% where deep convection occurs and (Formula presented.)). Observed tropospheric temperatures show variations in boundary layer capping strength over time consistent with the evolution of SST#. The CERES/EBAF v4 data confirm that associated cloud fraction changes over the colder waters dominate SWCRE. This observational evidence for the “pattern effect” noted in General Circulation Model simulations suggests that SST# captures much of this effect. The observed sensitivities (dSWCRE/d (Formula presented.) W·m−2·K−1, dSWCRE/dSST#≈−4.8W·m−2·K−1) largely reflect El Niño–Southern Oscillation. As El Niño develops, (Formula presented.) increases and SST# decreases (both increasing SWCRE). Only after the El Niño peak, SST# increases and SWCRE decreases. SST# is also relevant for the tropical temperature trend profile controversy and the discrepancy between observed and modeled equatorial Pacific SST trends. Causality and implications for future climates are discussed. ©2019. American Geophysical Union. All Rights Reserved."
"36994120200;57194610974;21735369200;47962387700;7102010848;","Large Uncertainties in Estimation of Tropical Tropopause Temperature Variabilities Due to Model Vertical Resolution",2019,"10.1029/2019GL084112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071259167&doi=10.1029%2f2019GL084112&partnerID=40&md5=0f3e78d32b857aa3a38c9d69e4cf0efd","Tropopause temperature (TPT) is a useful indicator and a key component of climate change. Well simulating its value and seasonal-to-decadal variability by climate models is still challenging. How the vertical resolution influences the representation of TPT and its response to a climate forcing is largely unknown. This study investigates TPT responses to sea surface temperatures using a series of model simulations in various vertical resolution. With high vertical resolution (HV-Res), the model gives a better representation of tropical TPTs in absolute values and seasonal variations. The corresponding changes in TPTs associated with sea surface temperature anomalies (El Niño–Southern Oscillation and Pacific Decadal Oscillation) are 30% stronger and more realistic in the HV-Res model. Such improvements may get benefits from better representations of equatorial waves with more realistic structure and stronger interannual variations. A proper vertical resolution is therefore essential to well simulate the stratosphere-troposphere coupling and should be used in climate change assessment. ©2019. American Geophysical Union. All Rights Reserved."
"57200205038;8511991900;7102423967;7409080503;35105101800;","Wildfire Impact on Environmental Thermodynamics and Severe Convective Storms",2019,"10.1029/2019GL084534","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071265919&doi=10.1029%2f2019GL084534&partnerID=40&md5=10a1cddd9e9b356a22341ecf994847bf","Wildfires are extreme events associated with weather, climate, and environment and have been increasing globally in frequency, burn season length, and burned area. It is of great interest to understand the impacts of wildfires on severe convective storms through releasing heat and aerosols into the atmosphere. We have developed a model capability that can account for the impact of sensible heat fluxes from wildfires on thermodynamics and is computationally efficient. The pyrocumulonimbus clouds associated with the Texas Mallard Fire on 11–12 May 2018 are well simulated by accounting for both heat and aerosols emitted from the wildfire. Both heat and aerosol effects increase low-level temperatures and midlevel buoyancy and enhance convective intensity. Intensified convection along with more supercooled liquid condensate due to stronger vertical transport results in larger hailstones and enhanced lightning. The effects of heat flux on the convective extremes are more significant than those of aerosol emissions. © 2019. The Authors."
"57193683861;57192695511;18133397500;55512674800;6603652793;8627503500;35547214900;","Radiative Forcing and Stratospheric Warming of Pyrocumulonimbus Smoke Aerosols: First Modeling Results With Multisensor (EPIC, CALIPSO, and CATS) Views from Space",2019,"10.1029/2019GL082360","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071233043&doi=10.1029%2f2019GL082360&partnerID=40&md5=d1e552c2a801f45a6c3d4351333bf224","Smoke particles can be injected by pyrocumulonimbus (pyroCb) in the upper troposphere and lower stratosphere, but their effects on the radiative budget of the planet remain elusive. Here, by focusing on the record-setting Pacific Northwest pyroCb event of August 2017, we show with satellite-based estimates of pyroCb emissions and injection heights in a chemical transport model (GEOS-Chem) that pyroCb smoke particles can result in radiative forcing of ∼0.02 W/m2 at the top of the atmosphere averaged globally in the 2 months following the event and up to 0.9 K/day heating in the Arctic upper troposphere and lower stratosphere. The modeled aerosol distributions agree with observations from satellites (Earth Polychromatic Imaging Camera [EPIC], Cloud-Aerosol Transport System [CATS], and Cloud-Aerosol Lidar with Orthogonal Polarization [CALIOP]), showing the hemispheric transport of pyroCb smoke aerosols with a lifetime of 5 months. Hence, warming by pyroCb aerosols can have similar temporal duration but opposite sign to the well-documented cooling of volcanic aerosols and be significant for climate prediction. ©2019. The Authors."
"55913339000;57201394954;56780996700;56158622800;","Effect of Aerosols on the Ice Cloud Properties Over the Tibetan Plateau",2019,"10.1029/2019JD030463","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071021248&doi=10.1029%2f2019JD030463&partnerID=40&md5=a0be1ce99a16986bd8d04dfa7bac44f3","With the highlight of environmental problems over the Tibetan Plateau (TP), aerosol pollution and the influence of this pollution on cloud properties are becoming a new area of research. Based on the aerosol index and cloud property parameters derived from satellite observations, in this study, the inconsistent effects of aerosols on ice cloud properties between daytime and nighttime over the TP are investigated. The results indicate that ice clouds are mainly distributed over the TP margin area, especially over the north slope, during both daytime and nighttime. The occurrence frequency of ice cloud is higher during the daytime than during the nighttime over the margin areas of the TP. Similarly, aerosols are mainly concentrated over the northern margin of the TP. A potential relationship may exist between the aerosol index and ice cloud properties. When the aerosol index increases from 0.05 to 0.17, the ice cloud droplet radius (ICDR) during the daytime decreases from 32.1 to 27.9 μm, while the ICDR during the nighttime remains almost constant (approximately 25 μm); furthermore, the ice water path (IWP) during the daytime decreases slightly due to the saturation effect, while the nocturnal IWP increases significantly. The changes in ice cloud optical depth (ICOD) during daytime and nighttime show significant and completely opposite trends. The removal of the influence of meteorological factors showed that aerosols have a more dominant influence than meteorological conditions on ice cloud properties (except for the nocturnal ICDR and IWP during the daytime). ©2019. American Geophysical Union. All Rights Reserved."
"57210829466;6701873414;7202784114;7003663305;56290437400;7006204393;6701752471;","Formation of Arctic Stratocumuli Through Atmospheric Radiative Cooling",2019,"10.1029/2018JD030189","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071630351&doi=10.1029%2f2018JD030189&partnerID=40&md5=511755cd86ec9f2965a907e5d913c6d6","Stratocumulus clouds are important to the Arctic climate because they are prevalent and exert a strong radiative forcing on the surface. However, relatively little is known about how stratocumulus clouds form in the Arctic. In this study, radiative transfer calculations are used to show that the timescale over which stably stratified Arctic temperature and water vapor profiles cool to saturation is less than typical residence times for individual air parcels in the Arctic. This result is consistent with previous studies in suggesting that elevated stratocumulus can form naturally through clear-sky radiative cooling during all seasons, without assistance from frontal lifting or other atmospheric forcing. Single column model simulations of the cloud formation process, after radiative cooling has resulted in saturation in a stably stratified profile, suggest that stratocumulus cloud properties are sensitive to the characteristics of the environment in which the formation process takes place. For example, sensitivity tests suggest that clouds may attain liquid water paths of over 50 g/m2 if they form in moist environments but may become locked in a low-liquid water path quasi steady state or dissipate within hours if they form in dry environments. A potential consequence of these sensitivities is that when an Arctic stratocumulus layer forms by radiative cooling, it is more likely to become optically thick, optically thin, or dissipate than it is to obtain an intermediate optical thickness. This could help explain why the cloudy and radiatively clear atmospheric states are so prevalent across the Arctic. ©2019. American Geophysical Union. All Rights Reserved."
"36678944300;57202078062;7403564495;57189843916;57211090732;56158622800;","Atmospheric Instability Dominates the Long-Term Variation of Cloud Vertical Overlap Over the Southern Great Plains Site",2019,"10.1029/2019JD030954","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071374397&doi=10.1029%2f2019JD030954&partnerID=40&md5=0a290e5595be47043a476106f6e85c0f","Accurate representation of cloud vertical overlap in climate models is particularly significant for predicting the total cloud fraction (TCF) and calculating radiative budget. It refers to the parameterization of overlap parameter—decorrelation length scale L—but the potential of dynamical factors in developing parameterization of L has still received far less attention. Using ground-based radar observation over Atmospheric Radiation Measurement Southern Great Plains site, here long-term seasonal-averaged L is retrieved and shows a very high anticorrelation with TCF from different data sets, indicating that TCF is sensitive to the way of cloud overlap. Therefore, combined with meteorological reanalysis data set, a robust multiple regression model between L and dynamical factors is built and exhibits smaller TCF bias compared with previous parameterization of L. Contribution calculation further verifies that atmospheric instability contributes 70% of L variation, indicating that it dominates the long-term variation of L over Southern Great Plains site. This finding implies that dynamical factors should be taken into account in the parameterization of L. ©2019. American Geophysical Union. All Rights Reserved."
"57210582290;7402966606;55727880700;57198776938;56463154100;","Sensitivity of Summer Precipitation Simulation to Microphysics Parameterization Over Eastern China: Convection-Permitting Regional Climate Simulation",2019,"10.1029/2019JD030295","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070948242&doi=10.1029%2f2019JD030295&partnerID=40&md5=e9d30066d95bbe35dfb1c31dbc3cb9ec","With a six-year (2009–2014) summer climate simulation using the Weather Research and Forecasting model at convection-permitting resolution (4-km grid spacing), the effects of microphysics parameterization (MP) schemes on precipitation characteristics are investigated in this study. The convection-permitting simulations employ three popular MP schemes, namely, Lin (single-moment bulk MP), Weather Research and Forecasting Single-Moment 5-class (one-moment and mixed-phased MP), and Thompson (two-moment and mixed-phase MP) scheme. By evaluating the simulations against the CMORPH, rain gauge (Station), and ERA-Interim data, it is found that the convection-permitting model reproduce well the summer precipitation amount and the associated large-scale atmospheric circulations, which are insensitive to the choice of MP schemes. The simulations with three MP schemes overestimate the precipitation amount, especially over the Yangtze-Huaihe River Valley. The overestimations may be due to the systematic biases, and cannot be significantly reduced by using different MP schemes. Moreover, all simulations capture well the major features of precipitation diurnal variations and their transition characteristics, but they significantly overestimate the precipitation frequency while underestimate the precipitation intensity. The analysis on the microphysical hydrometeors shows that the model-simulated precipitation amount is considerably affected by the vertical profiles of solid hydrometeors, especially the snow and graupel particles. The Thompson scheme creates more snow particles and less graupel than the other schemes, while produces the least precipitation amount that best matches the CMORPH. ©2019. American Geophysical Union. All Rights Reserved."
"23095483400;16444232500;56039057300;57208121852;36171703500;56250185400;57206038917;35235146400;6506718302;57203053317;","The global aerosol-climate model ECHAM6.3-HAM2.3-Part 2: Cloud evaluation, aerosol radiative forcing, and climate sensitivity",2019,"10.5194/gmd-12-3609-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071235195&doi=10.5194%2fgmd-12-3609-2019&partnerID=40&md5=5b46beb191002250765800ba146684d3","The global aerosol-climate model ECHAM6.3-HAM2.3 (E63H23) as well as the previous model versions ECHAM5.5-HAM2.0 (E55H20) and ECHAM6.1-HAM2.2 (E61H22) are evaluated using global observational datasets for clouds and precipitation. In E63H23, the amount of low clouds, the liquid and ice water path, and cloud radiative effects are more realistic than in previous model versions. E63H23 has a more physically based aerosol activation scheme, improvements in the cloud cover scheme, changes in the detrainment of convective clouds, changes in the sticking efficiency for the accretion of ice crystals by snow, consistent ice crystal shapes throughout the model, and changes in mixed-phase freezing; an inconsistency in ice crystal number concentration (ICNC) in cirrus clouds was also removed. Common biases in ECHAM and in E63H23 (and in previous ECHAM-HAM versions) are a cloud amount in stratocumulus regions that is too low and deep convective clouds over the Atlantic and Pacific oceans that form too close to the continents (while tropical land precipitation is underestimated). There are indications that ICNCs are overestimated in E63H23. Since clouds are important for effective radiative forcing due to aerosol-radiation and aerosol-cloud interactions (ERFariCaci) and equilibrium climate sensitivity (ECS), differences in ERFariCaci and ECS between the model versions were also analyzed. ERFariCaci is weaker in E63H23 (-1:0 W m-2) than in E61H22 (-1:2 W m-2) (or E55H20;-1:1 W m-2). This is caused by the weaker shortwave ERFariCaci (a new aerosol activation scheme and sea salt emission parameterization in E63H23, more realistic simulation of cloud water) overcompensating for the weaker longwave ERFariCaci (removal of an inconsistency in ICNC in cirrus clouds in E61H22). The decrease in ECS in E63H23 (2.5 K) compared to E61H22 (2.8 K) is due to changes in the entrainment rate for shallow convection (affecting the cloud amount feedback) and a stronger cloud phase feedback. Experiments with minimum cloud droplet number concentrations (CDNCmin) of 40 cm-3 or 10 cm-3 show that a higher value of CDNCmin reduces ERFariCaci as well as ECS in E63H23. © 2019 The Author(s)."
"57195136271;35611334800;35227762400;6602600408;","Arctic clouds in ECHAM6 and their sensitivity to cloud microphysics and surface fluxes",2019,"10.5194/acp-19-10571-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071222928&doi=10.5194%2facp-19-10571-2019&partnerID=40&md5=7a31bccb067502c2df665bc3d6663660","Compared to other climate models, the MPI-ESM/ECHAM6 is one of the few models that is able to realistically simulate the typical two-state radiative structure of the Arctic boundary layer and also is able to sustain liquid water at low temperatures as is often observed in high latitudes. To identify processes in the model that are responsible for the abovementioned features, we compare cloud properties from ECHAM6 to observations from CALIPSO-GOCCP using the COSP satellite simulator and perform sensitivity runs. The comparison shows that the model is able to reproduce the spatial distribution and cloud amount in the Arctic to some extent but a positive bias in cloud fraction is found in high latitudes, which is related to an overestimation of low- and high-level clouds. We mainly focus on low-level clouds and show that the overestimated cloud amount is connected to surfaces that are covered with snow or ice and is mainly caused by an overestimation of liquid-containing clouds. The overestimated amount of Arctic low-level liquid clouds can be related to insufficient efficiency of the Wegener-Bergeron-Findeisen (WBF) process but revising this process alone is not sufficient to improve cloud phase on a global scale as it also introduces a negative bias over oceanic regions in high latitudes. Additionally, this measure transformed the positive bias in low-level liquid clouds into a positive bias of low-level ice clouds, keeping the amount of low-level clouds almost unchanged. To avoid this spurious increase in ice clouds, we allowed for supersaturation with respect to ice using a temperature-weighted scheme for saturation vapor pressure but this measure, together with a more effective WBF process, might already be too efficient at removing clouds as it introduces a negative cloud cover bias. We additionally explored the sensitivity of low-level cloud cover to the strength of surface heat fluxes; by increasing surface mixing, the observed cloud cover and cloud phase bias could also be reduced. As ECHAM6 already mixes too strongly in the Arctic regions, it is questionable if one can physically justify it to increase mixing even further. © 2019 Author(s)."
"57202219487;7006306835;16636807900;","Investigating the Fast Response of Precipitation Intensity and Boundary Layer Temperature to Atmospheric Heating Using a Cloud-Resolving Model",2019,"10.1029/2019GL082408","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070763088&doi=10.1029%2f2019GL082408&partnerID=40&md5=6f83fbb10b4f8bfa1d548b106e65efe1","Coarse-resolution global climate models cannot explicitly resolve the intensity distribution of tropical precipitation and how it responds to a forcing. We use a cloud-resolving model to study how imposed atmospheric radiative heating (such as that caused by greenhouse gases or absorbing aerosols) may alter precipitation intensity in the setting of radiative-convective equilibrium. It is found that the decrease in total precipitation is realized through preferentially reducing weak events. The intensity of strong precipitation events is maintained by a cancellation between the moistening of air parcels and weakening of updrafts. A boundary layer energy budget analysis suggests that free-tropospheric heating raises boundary layer temperatures mainly through a reduction in rain reevaporation. This insight leads to a predictive scaling for the surface sensible and latent flux changes. The results imply that cloud microphysical processes play a key role in shaping the temperature and precipitation responses to atmospheric heating. ©2019. The Authors."
"55705441800;7006698304;6701754792;55910831200;55975845400;","The Relationship of Cloud Number and Size With Their Large-Scale Environment in Deep Tropical Convection",2019,"10.1029/2019GL083964","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070760058&doi=10.1029%2f2019GL083964&partnerID=40&md5=b69078aeec96e504ca17e5acb3d953ac","Accurately representing the properties and impact of tropical convection in climate models requires an understanding of the relationships between the state of a convective cloud ensemble and the environment it is embedded in. We investigate this relationship using 13 years of radar observations in the tropics. Specifically, we focus on convective cell number and size and quantify their relationship to atmospheric stability, midtropospheric vertical motion and humidity. We find several key convective states embedded in their own unique environments. The most area-averaged rainfall occurs with a moderate number of moderate size convective cell in an environment of high humidity, strong vertical ascent, and moderate convective available potential energy (CAPE) and convective inhibition (CIN). The strongest rainfall intensities are found with few large cells. Those exist in a dry and subsiding environment with both high CAPE and CIN. Large numbers of convective cells are associated with small CAPE and CIN, weak ascent, and a moist midtroposphere. ©2019. American Geophysical Union. All Rights Reserved."
"56521532600;15026371500;55087038900;","Hemispheric Asymmetry of Tropical Expansion Under CO2 Forcing",2019,"10.1029/2019GL083695","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070742172&doi=10.1029%2f2019GL083695&partnerID=40&md5=5b2c70272fdb958f10633d5eb9e4abe2","The degree of Hadley cell expansion under global warming will have a substantial impact on changing rainfall patterns. Most previous studies have quantified changes in total tropical width, focused on the Southern Hemisphere Hadley cell or considered each hemisphere's response to a multitude of anthropogenic forcings. It is shown here that under exclusive CO2 forcing, climate models predict twice as much Hadley cell expansion in the Southern Hemisphere relative to the Northern Hemisphere. This asymmetry is present in the annual mean expansion and all seasons except boreal autumn. It is robust across models and Hadley cell edge definitions. It is surprising since asymmetries in simulated Hadley cell expansion are typically attributed to stratospheric ozone depletion or aerosol emission. Its primary cause is smaller sensitivity of the Northern Hemisphere Hadley cell to static stability changes. The pattern of sea surface warming and the CO2 direct radiative effect also contribute to the asymmetry. ©2019. American Geophysical Union. All Rights Reserved."
"57193221521;57219982553;56707416400;57209828668;","Optical characterization of cloud and aerosol of the temperate zone",2019,"10.1007/s11869-019-00716-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068830501&doi=10.1007%2fs11869-019-00716-6&partnerID=40&md5=db1ca42e9bf5d374c68a952213bee50b","Aerosol and cloud optical data of the network AERONET/PHOTONS are in major importance in climate change and air quality studies. Sun photometers allow the determination of cloud and aerosol optical depths and the particle size distribution of aerosol for many sites distributed over large four zones belongs to the temperate areas: Mediterranean, maritime, humid subtropical, and continental and dry. The histograms of cloud occurrence frequencies reveal the dominance variation in the interval (20.100) relating to Stratus and Altostratus, maximum reaches (~ 70%) recorded at eastern Asia (China). For values below 20, the histograms are different from those of Equatorial zone but modeled into two classes, staircase and non-staircase shapes, depending on the weather conditions. The monthly aerosol optical depth averages at 0.5 μm show the highest values in summer, a maximum reach 1.6 at Eastern Asia and coincides with the highest cloud optical depth particularly for Asian sites. Seasonal average of aerosol particle size distribution records larger amplitudes of both fine and coarse modes in the Asian sites especially in the East two to three times higher than those in other zones. The average radius of fine mode is around 0.17 μm expressing high anthropogenic local pollution. The coarse mode around 2.75 μm is very important in Western India with a maximum concentration in summer as seasonal desert dust advections concern. © 2019, Springer Nature B.V."
"57193882808;52364737200;","Separating dynamic and thermodynamic impacts of climate change on daytime convective development over land",2019,"10.1175/JCLI-D-19-0007.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072121289&doi=10.1175%2fJCLI-D-19-0007.1&partnerID=40&md5=68afd4a780df66d4bb3c7a46af251439","Climate change affects the dynamics and thermodynamics of moist convection. Changes in the dynamics concern, for instance, an increase of convection strength due to increases of convective available potential energy (CAPE). Thermodynamics involve increases in water vapor that the warmer atmosphere can hold and convection can work with. Small-scale simulations are conducted to separate these two components for daytime development of unorganized convection over land. The simulations apply a novel modeling technique referred to as the piggybacking (or master–slave) approach and consider the global climate model (GCM)-predicted change of atmospheric temperature and moisture profiles in the Amazon region at the end of the century under a business-as-usual scenario. The simulations show that the dynamic impact dominates because changes in cloudiness and rainfall come from cloud dynamics considerations, such as the change in CAPE and convective inhibition (CIN) combined with the impact of environmental relative humidity (RH) on deep convection. The small RH reduction between the current and future climate significantly affects the mean surface rain accumulation as it changes from a small reduction to a small increase when the RH decrease is eliminated. The thermodynamic impact on cloudiness and precipitation is generally small, with the extreme rainfall intensifying much less than expected from an atmospheric moisture increase. These results are discussed in the context of previous studies concerning climate change–induced modifications of moist convection. Future research directions applying the piggybacking method are discussed. © 2019 American Meteorological Society."
"57194933853;7004697981;6603335688;8234510900;26639333200;7102843206;","Sensitivity of a tropical montane cloud forest to climate change, present, past and future: Mt. Marsabit, N. Kenya",2019,"10.1016/j.quascirev.2019.06.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067387961&doi=10.1016%2fj.quascirev.2019.06.016&partnerID=40&md5=5eb297f66bca0affd06aeaa8ec9879b1","During the Last Glacial Maximum (LGM) lowland forests contracted throughout the tropics but, by contrast, many montane forest taxa moved to lower elevations. These taxa are often found in cloud forests, which are globally important ecosystems that depend on the capture of atmospheric water from fog drifting through the canopy, here referred to as occult precipitation. Understanding the response of tropical montane taxa to climate variations is limited by a lack of modern data on fog capture; whereas palaeoecological data only provide indirect evidence for its importance. Hence, the response of vegetation to fog capture is not considered in palaeo-estimates of precipitation. We develop a method that uses satellite Normalized Difference Vegetation Index (NDVI) data to estimate the annual amount of occult precipitation and investigate the sensitivity of a cloud forest to past and future changes in both rainfall and occult precipitation. We apply this method using satellite and meteorological data from 1982 to 2015 collected at Mt Marsabit, which is located in northern Kenya (2.34∘ N, 37.97∘ E, summit 1707 m a.s.l.). Mt Marsabit has a sub-humid tropical montane cloud forest at its summit that is excessively green for the amount of rain it receives. We estimate the annual amount of occult precipitation for current conditions at about 900 mm y−1 which is more than the average annual rainfall of 700 mm y−1. This is consistent with the observation that, for the wider Marsabit area, interannual variations in NDVI are more closely linked to changes in cloud-base height (r2=0.87) than to changes in rainfall (r2=0.67). We investigate the sensitivity of forest extent to past and future changes; for the LGM we estimate that cloud-base height decreased by 500 m in response to a 4 ∘C cooling and that this caused a 20%–100% increase in forest area despite a 30% decrease in rainfall, a 22% decrease in atmospheric humidity and a substantial reduction of atmospheric CO2 levels (values representative for mountains in Kenya during the LGM). An expected increase of 250 m in the cloud-base height associated with a future 2 ∘C global warming is likely to reduce forest extent by 50%–100%. Our results indicate that the satellite vegetation record is useful to estimate modern hydrological inputs into drier cloud forests (up to 2000 mm y−1) and that this information can be used to estimate the contribution of occult precipitation to altitudinal displacements of tropical montane cloud-forest species during the Quaternary. © 2019 Elsevier Ltd"
"57201492755;23007626000;7003264533;7006235116;","A classification of synoptic weather patterns linked to extreme rainfall over the Limpopo River Basin in southern Africa",2019,"10.1007/s00382-019-04829-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068855866&doi=10.1007%2fs00382-019-04829-7&partnerID=40&md5=aba4e1b0c60ab6229442dfde412feb2f","In the last few decades, the Limpopo River Basin (LRB) has experienced a number of extreme rainfall events which were responsible for considerable socio-economic and environmental impacts. Most of the population here is poor and dependent on rain-fed agriculture. In order to better understand these events over the LRB, CHIRPS, 0.05° gridded rainfall data are used to identify the daily extreme events, analyse their interannual variability and examine relationships with large scale climate modes over the 1981–2016 period. Analysis of the top 20 events suggests a pattern with rainfall generally decreasing from the eastern to western parts of the basin. Typically, the highest rainfall amounts occur over the regions where there are steep topographical gradients between the mountainous regions of northeastern South Africa and the Mozambican floodplains. Almost half of the top 200 extreme events are associated with tropical extra-tropical cloud bands (48%), with tropical low-pressure systems (28%), Mesoscale Convective Systems (14%), and cut-off lows (10%) in the mid-upper atmosphere, also making sizeable contributions. The monthly distribution of the events showed that most of the events occurred during the late summer months (January–March) when tropical lows and cloud bands are more common. On interannual time-scales, most of the summers with above average number of events coincide with La Niña conditions and, to lesser extent, a positive subtropical South Indian Ocean Dipole. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"57201462302;57196496271;7102953444;8934032500;14324150200;36990295500;6602613489;","Numerical simulation of surface solar radiation over Southern Africa. Part 2: projections of regional and global climate models",2019,"10.1007/s00382-019-04817-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066250054&doi=10.1007%2fs00382-019-04817-x&partnerID=40&md5=28456f7aa8025a89629d29baa3dfca9a","In the second part of this study, possible impacts of climate change on Surface Solar Radiation (SSR) in Southern Africa (SA) are evaluated. We use outputs from 20 regional climate simulations from five Regional Climate Models (RCM) that participate in the Coordinated Regional Downscaling Experiment program over the African domain (CORDEX-Africa) along with their 10 driving Global Climate Models (GCM) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Multi-model mean projections of SSR trends are consistent between the GCMs and their nested RCMs. However, this consistency is not found for each GCM/RCM setup. Over the centre of SA, GCMs and RCMs project a statistically significant increase in SSR by 2099 of about + 1 W/m2 per decade in RCP4.5 (+ 1.5 W/m2 per decade in RCP8.5) during the DJF season in their multi-model means. Over Eastern Equatorial Africa (EA-E) a statistically significant decrease in SSR of about − 1.5 W/m2 per decade in RCP4.5 (− 2 W/m2 per decade in RCP8.5) is found in the ensemble means in DJF, whereas in JJA SSR is predicted to increase by about + 0.5 W/m2 per decade under RCP4.5 (+ 1 W/m2 per decade in RCP8.5). SSR projections are fairly similar between RCP8.5 and RCP4.5 before 2050 and then the differences between those two scenarios increase up to about 1 W/m2 per decade with larger changes in RCP8.5 than in RCP4.5 scenario. These SSR evolutions are generally consistent with projected changes in Cloud Cover Fraction over SA and may also related to the changes in atmosphere water vapor content. SSR change signals emerge earlier out of internal variability estimated from reanalyses (European Centre for Medium-Range Weather Forecasts Reanalysis ERA-Interim, ERAIN) in DJF in RCMs than in GCMs, which suggests a higher sensitivity of RCMs to the forcing RCP scenarios than their driving GCMs in simulating SSR changes. Uncertainty in SSR change projections over SA is dominated by the internal climate variability before 2050, and after that model and scenario uncertainties become as important as internal variability until the end of the 21st century. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"57215699608;55177012900;8846887600;6602831555;15724543600;7004060399;","Stratospheric water vapor: an important climate feedback",2019,"10.1007/s00382-019-04721-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068825943&doi=10.1007%2fs00382-019-04721-4&partnerID=40&md5=c54efe4657e481a9102fbeeba63e96dd","The role of stratospheric water vapor (SWV) changes, in response to increasing CO 2, as a feedback component of quantitative significance for climate sensitivity has remained controversial. Here, we calculate the SWV climate feedback under abrupt CO 2 quadrupling in the CMIP5 ensemble of models. All models robustly show a moistening of the stratosphere, causing a global mean net stratosphere adjusted radiative perturbation of 0.89±0.27Wm-2 at the reference tropopause. The stratospheric temperature adjustment is a crucial component of this radiative perturbation. The associated climate feedback is 0.17±0.05Wm-2K-1, with a considerable inter-model range of 0.12–0.28 Wm-2K-1. Taking into account the rise in tropopause height under 4 × CO 2 slightly reduces the feedback to 0.15±0.04Wm-2K-1, with a range of 0.10–0.26Wm-2K-1. The SWV radiative perturbation peaks in the midlatitudes and not the tropics: this is due primarily to increases in SWV in the extratropical lowermost stratosphere, which cause the majority (over three quarters) of the global mean feedback. Based on these results, we suggest an increased focus on understanding drivers of water vapor trends in the extratropical lowermost stratosphere. We conclude that the SWV feedback is important, being on the same order of magnitude as the global mean surface albedo and cloud feedbacks in the multi-model mean. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"57203098840;55718911800;55999590500;6506180220;6506258154;55366522200;55716266100;56068376200;55431445800;57145546300;","Organic coating on sulfate and soot particles during late summer in the Svalbard Archipelago",2019,"10.5194/acp-19-10433-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070798128&doi=10.5194%2facp-19-10433-2019&partnerID=40&md5=cc4225d941e3327871e63bdfd856d356","Interaction of anthropogenic particles with radiation and clouds plays an important role in Arctic climate change. The mixing state of aerosols is a key parameter to influence aerosol radiation and aerosol-cloud interactions. However, little is known of this parameter in the Arctic, preventing an accurate representation of this information in global models. Here we used transmission electron microscopy with energy-dispersive X-ray spectrometry, scanning electron microscopy, nanoscale secondary ion mass spectrometry, and atomic forces microscopy to determine the size and mixing state of individual sulfate and carbonaceous particles at 100 nm to 2 collected in the Svalbard Archipelago in summer. We found that 74 % by number of non-sea-salt sulfate particles were coated with organic matter (OM); 20 % of sulfate particles also had soot inclusions which only appeared in the OM coating. The OM coating is estimated to contribute 63 % of the particle volume on average. To understand how OM coating influences optical properties of sulfate particles, a Mie core-shell model was applied to calculate optical properties of individual sulfate particles. Our result shows that the absorption cross section of individual OM-coated particles significantly increased when assuming the OM coating as light-absorbing brown carbon. Microscopic observations here suggest that OM modulates the mixing structure of fine Arctic sulfate particles, which may determine their hygroscopicity and optical properties. © 2019 Copernicus GmbH. All rights reserved."
"56531065100;57208275387;57204914178;57203579680;6603653680;","Strong contribution of rapid urbanization and urban agglomeration development to regional thermal environment dynamics and evolution",2019,"10.1016/j.foreco.2019.05.046","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065894936&doi=10.1016%2fj.foreco.2019.05.046&partnerID=40&md5=d4d805a46f719fac2501b668a840df24","Urbanization has significantly transformed natural surfaces into impervious surfaces, which has subsequently disturbed the balance of the global surface thermal energy. However, key landscape dynamic transfer processes that can affect land surface temperature (LST) and regional thermal environment (RTE) remain poorly understood, especially in the context of urban agglomerations. Hence we selected one of the world's most rapidly urbanized regions – the Pearl-River-Delta Metropolitan Region (PRDR) located in southern China as the case. With the help of Google Cloud Computing, Markov model, and spatial analyses, we have further quantified the strong contributions of urbanization and urban agglomeration development to RTE dynamics and evolution. Specifically, we revealed (1) the cooling effects of ecological land loss and gain are significantly different, which provides evidence that the existing natural ecosystems (especially forests) are valuable for climatic adaptation because newly constructed ecological land does not provide the same cooling effect. (2) We found that the RTE is not only influenced by land cover patterns and process but also significantly dominated by the specific land conversion processes. (3) From 1995 to 2015 in the PRDR, built-up land increased significantly, while the ecological land was significantly reduced, and the isolated urban heat islands were gradually connected and interacted with each other, forming the regional heat island. (4) We also proposed that the relationship between urbanization rate and temperature (RLST) may conform to the Environmental Kuznets Curve. This study enhances the understanding of RTE dynamics and evolution in urban agglomeration and provides important insights into existing natural ecosystem protection and climate adaptation planning. © 2019 Elsevier B.V."
"22981684600;57210447653;","True eddy accumulation trace gas flux measurements: Proof of concept",2019,"10.5194/amt-12-4393-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070756502&doi=10.5194%2famt-12-4393-2019&partnerID=40&md5=b9a7bc3dd5751a3753cd2560e3556d60","Micrometeorological methods to quantify fluxes of atmospheric constituents are key to understanding and managing the impact of land surface sources and sinks on air quality and atmospheric composition. Important greenhouse gases are water vapor, carbon dioxide, methane, and nitrous oxide. Further important atmospheric constituents are aerosols, which impact air quality and cloud formation, and volatile organic compounds. Many atmospheric constituents therefore critically affect the health of ecosystems and humans, as well as climate. The micrometeorological eddy covariance (EC) method has evolved as the method of choice for CO2 and water vapor flux measurements using fast-response gas analyzers. While the EC method has also been used to measure other atmospheric constituents including methane, nitrous oxide, and ozone, the often relatively small fluxes of these constituents over ecosystems are much more challenging to measure using eddy covariance than CO2 and water vapor fluxes. For many further atmospheric constituents, eddy covariance is not an option due to the lack of sufficiently accurate and fast-response gas analyzers. Therefore, alternative flux measurement methods are required for the observation of atmospheric constituent fluxes for which no fast-response gas analyzers exist or which require more accurate measurements. True eddy accumulation (TEA) is a direct flux measurement technique capable of using slow-response gas analyzers. Unlike its more frequently used derivative, known as the relaxed eddy accumulation (REA) method, TEA does not require the use of proxies and is therefore superior to the indirect REA method. The true eddy accumulation method is by design ideally suited for measuring a wide range of trace gases and other conserved constituents transported with the air. This is because TEA obtains whole air samples and is, in combination with constituent-specific fast or slow analyzers, a universal method for conserved scalars. Despite the recognized value of the method, true eddy accumulation flux measurements remain very challenging to perform as they require fast and dynamic modulation of the air sampling mass flow rate proportional to the magnitude of the instantaneous vertical wind velocity. Appropriate techniques for dynamic mass flow control have long been unavailable, preventing the unlocking of the TEA method's potential for more than 40 years. Recently, a new dynamic and accurate mass flow controller which can resolve turbulence at a frequency of 10 Hz and higher has been developed by the first author. This study presents the proof of concept that practical true eddy accumulation trace gas flux measurements are possible today using dynamic mass flow control, advanced real-time processing of wind measurements, and fully automatic gas handling. We describe setup and methods of the TEA and EC reference flux measurements. The experiment was conducted over grassland and comprised 7 d of continuous flux measurements at 30 min flux integration intervals. The results show that fluxes obtained by TEA compared favorably to EC reference flux measurements, with coefficients of determination of up to 86 % and a slope of 0.98. We present a quantitative analysis of uncertainties of the mass flow control system, the gas analyzer, and gas handling system and their impact on trace gas flux uncertainty, the impact of different approaches to coordinate rotation, and uncertainties of vertical wind velocity measurements. Challenges of TEA are highlighted and solutions presented. The current results are put into the context of previous works. Finally, based on the current successful proof of concept, we suggest specific improvements towards long-term and reliable true eddy accumulation flux measurements. © 2019 Author(s)."
"57197760821;13403899000;14007691200;6603933756;6602624109;6602341538;55225894400;7005134081;56259852000;6506883710;15127430500;35334472800;55922940500;6603599576;7004587644;6506730133;7202802701;56593223000;23476421000;6603821988;7004402705;55519833300;9249656500;6504688501;8732171100;6701511321;7801544868;7202699800;6506553245;7004966070;16029719200;7003800456;7005723936;7006532784;7003683808;23012746800;55183670500;10739772300;57190047135;56797095600;","Clear-sky ultraviolet radiation modelling using output from the Chemistry Climate Model Initiative",2019,"10.5194/acp-19-10087-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070641398&doi=10.5194%2facp-19-10087-2019&partnerID=40&md5=71298aab62379660fb3126339534a6d0","We have derived values of the ultraviolet index (UVI) at solar noon using the Tropospheric Ultraviolet Model (TUV) driven by ozone, temperature and aerosol fields from climate simulations of the first phase of the Chemistry-Climate Model Initiative (CCMI-1). Since clouds remain one of the largest uncertainties in climate projections, we simulated only the clear-sky UVI. We compared the modelled UVI climatologies against present-day climatological values of UVI derived from both satellite data (the OMI-Aura OMUVBd product) and ground-based measurements (from the NDACC network). Depending on the region, relative differences between the UVI obtained from CCMI/TUV calculations and the ground-based measurements ranged between-5:9 % and 10.6 %. We then calculated the UVI evolution throughout the 21st century for the four Representative Concentration Pathways (RCPs 2.6, 4.5, 6.0 and 8.5). Compared to 1960s values, we found an average increase in the UVI in 2100 (of 2 %-4 %) in the tropical belt (30° N-30° S). For the mid-latitudes, we observed a 1.8 % to 3.4 % increase in the Southern Hemisphere for RCPs 2.6, 4.5 and 6.0 and found a 2.3 % decrease in RCP 8.5. Higher increases in UVI are projected in the Northern Hemisphere except for RCP 8.5. At high latitudes, ozone recovery is well identified and induces a complete return of mean UVI levels to 1960 values for RCP 8.5 in the Southern Hemisphere. In the Northern Hemisphere, UVI levels in 2100 are higher by 0.5 % to 5.5 % for RCPs 2.6, 4.5 and 6.0 and they are lower by 7.9 % for RCP 8.5. We analysed the impacts of greenhouse gases (GHGs) and ozone-depleting substances (ODSs) on UVI from 1960 by comparing CCMI sensitivity simulations (1960-2100) with fixed GHGs or ODSs at their respective 1960 levels. As expected with ODS fixed at their 1960 levels, there is no large decrease in ozone levels and consequently no sudden increase in UVI levels. With fixed GHG, we observed a delayed return of ozone to 1960 values, with a corresponding pattern of change observed on UVI, and looking at the UVI difference between 2090s values and 1960s values, we found an 8 % increase in the tropical belt during the summer of each hemisphere. Finally we show that, while in the Southern Hemisphere the UVI is mainly driven by total ozone column, in the Northern Hemisphere both total ozone column and aerosol optical depth drive UVI levels, with aerosol optical depth having twice as much influence on the UVI as total ozone column does. © 2019 Author(s)."
"9275665400;38762392200;7103000184;","Revised treatment of wet scavenging processes dramatically improves GEOS-Chem 12.0.0 simulations of surface nitric acid, nitrate, and ammonium over the United States",2019,"10.5194/gmd-12-3439-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070416505&doi=10.5194%2fgmd-12-3439-2019&partnerID=40&md5=cfa341df95fa07e461a6d02941dd4c30","The widely used community model GEOS-Chem 12.0.0 and previous versions have been recognized to significantly overestimate the concentrations of gaseous nitric acid, aerosol nitrate, and aerosol ammonium over the United States. The concentrations of nitric acid are also significantly overpredicted in most global models participating in a recent model intercomparison study. In this study, we show that most or all of this overestimation issue appears to be associated with wet scavenging processes. The replacement of constant in-cloud condensation water (ICCW) assumed in GEOS-Chem standard versions with one varying with location and time from the assimilated meteorology significantly reduces mass loadings of nitrate and ammonium during the wintertime, while the employment of an empirical washout rate for nitric acid significantly decreases mass concentrations of nitric acid and ammonium during the summertime. Compared to the standard version, GEOS-Chem with updated ICCW and washout rate significantly reduces the simulated annual mean mass concentrations of nitric acid, nitrate, and ammonium at surface monitoring network sites in the US from 2.04 to 1.03, 1.89 to 0.88, and 1.09 to 0.68 μg m-3, respectively, in much better agreement with corresponding observed values of 0.83, 0.70, and 0.60 μg m-3, respectively. In addition, the agreement of model-simulated seasonal variations of corresponding species with measurements is also improved. The updated wet scavenging scheme improves the skill of the model in predicting nitric acid, nitrate, and ammonium concentrations, which are important species for air quality and climate. © Author(s) 2019."
"56276584900;10042470700;","Efficacy of black carbon aerosols: The role of shortwave cloud feedback",2019,"10.1088/1748-9326/ab21e7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072711403&doi=10.1088%2f1748-9326%2fab21e7&partnerID=40&md5=dab35964525ab0f8d5b3201553626f6f","Using idealized climate model simulations, we investigate the effectiveness of black carbon (BC) aerosols in warming the planet relative to CO2 forcing. We find that a 60-fold increase in the BC aerosol mixing ratio from the present-day levels leads to the same equilibrium global mean surface warming (∼4.1 K) as for a doubling of atmospheric CO2 concentration. However, the radiative forcing is larger (∼5.5 Wm-2) in the BC case relative to the doubled CO2 case (∼3.8 Wm-2) for the same surface warming indicating the efficacy (a metric for measuring the effectiveness) of BC aerosols to be less than CO2. The lower efficacy of BC aerosols is related to the differences in the shortwave (SW) cloud feedback: negative in the BC case but positive in the CO2 case. In the BC case, the negative SW cloud feedback is related to an increase in the tropical low clouds which is associated with a northward shift (∼7) of the Intertropical Convergence Zone (ITCZ). Further, we show that in the BC case fast precipitation suppression offsets the surface temperature mediated precipitation response and causes ∼8% net decline in the global mean precipitation. Our study suggests that a feedback between the location of ITCZ and the interhemispheric temperature could exist, and the consequent SW cloud feedback could be contributing to the lower efficacy of BC aerosols. Therefore, an improved representation of low clouds in climate models is likely the key to understand the global climate sensitivity to BC aerosols. © 2019 The Author(s). Published by IOP Publishing Ltd."
"57203318983;56536745100;57203053317;","Response of Arctic mixed-phase clouds to aerosol perturbations under different surface forcings",2019,"10.5194/acp-19-9847-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073886826&doi=10.5194%2facp-19-9847-2019&partnerID=40&md5=5774a16663eaaddc27d5e875315008ae","The formation and persistence of low-lying mixed-phase clouds (MPCs) in the Arctic depends on a multitude of processes, such as surface conditions, the environmental state, air mass advection, and the ambient aerosol concentration. In this study, we focus on the relative importance of different instantaneous aerosol perturbations (cloud condensation nuclei and ice-nucleating particles; CCN and INPs, respectively) on MPC properties in the European Arctic. To address this topic, we performed high-resolution large-eddy simulation (LES) experiments using the Consortium for Small-scale Modeling (COSMO) model and designed a case study for the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Motivated by ongoing sea ice retreat, we performed all sensitivity studies over open ocean and sea ice to investigate the effect of changing surface conditions. We find that surface conditions highly impact cloud dynamics, consistent with the ACCACIA observations: over sea ice, a rather homogeneous, optically thin, mixed-phase stratus cloud forms. In contrast, the MPC over the open ocean has a stratocumulus-like cloud structure. With cumuli feeding moisture into the stratus layer, the cloud over the open ocean features a higher liquid (LWP) and ice water path (IWP) and has a lifted cloud base and cloud top compared to the cloud over sea ice. Furthermore, we analyzed the aerosol impact on the sea ice and open ocean cloud regime. Perturbation aerosol concentrations relevant for CCN activation were increased to a range between 100 and 1000 cm-3 and icenucleating particle perturbations were increased by 100% and 300% compared to the background concentration (at every grid point and at all levels). The perturbations are prognostic to allow for fully interactive aerosol-cloud interactions. Perturbations in the INP concentration increase IWP and decrease LWP consistently in both regimes. The cloud microphysical response to potential CCN perturbations occurs faster in the stratocumulus regime over the ocean, where the increased moisture flux favors rapid cloud droplet formation and growth, leading to an increase in LWP following the aerosol injection. In addition, IWP increases through new ice crystal formation by increased immersion freezing, cloud top rise, and subsequent growth by deposition. Over sea ice, the maximum response in LWP and IWP is delayed and weakened compared to the response over the open ocean surface. Additionally, we find the long-term response to aerosol perturbations to be highly dependent on the cloud regime. Over the open ocean, LWP perturbations are efficiently buffered after 18 h simulation time. Increased ice and precipitation formation relax the LWP back to its unperturbed range. On the contrary, over sea ice the cloud evolution remains substantially perturbed with CCN perturbations ranging from 200 to 1000CCNcm-3. © 2019 Author(s)."
"6701896839;35611907100;55503932700;53879349100;7101604215;7005803643;","Cloud cover and delayed herbivory relative to timing of spring onset interact to dampen climate change impacts on net ecosystem exchange in a coastal Alaskan wetland",2019,"10.1088/1748-9326/ab1c91","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072695435&doi=10.1088%2f1748-9326%2fab1c91&partnerID=40&md5=8b9ff08ab60d13c0d3f1ec94e6d7abaf","Rapid warming in northern ecosystems over the past four decades has resulted in earlier spring, increased precipitation, and altered timing of plant-animal interactions, such as herbivory. Advanced spring phenology can lead to longer growing seasons and increased carbon (C) uptake. Greater precipitation coincides with greater cloud cover possibly suppressing photosynthesis. Timing of herbivory relative to spring phenology influences plant biomass. None of these changes are mutually exclusive and their interactions could lead to unexpected consequences for Arctic ecosystem function. We examined the influence of advanced spring phenology, cloud cover, and timing of grazing on C exchange in the Yukon-Kuskokwim Delta of western Alaska for three years. We combined advancement of the growing season using passive-warming open-top chambers (OTC) with controlled timing of goose grazing (early, typical, and late season) and removal of grazing. We also monitored natural variation in incident sunlight to examine the C exchange consequences of these interacting forcings. We monitored net ecosystem exchange of C (NEE) hourly using an autochamber system. Data were used to construct daily light curves for each experimental plot and sunlight data coupled with a clear-sky model was used to quantify daily and seasonal NEE over a range of incident sunlight conditions. Cloudy days resulted in the largest suppression of NEE, reducing C uptake by approximately 2 g C m-2 d-1 regardless of the timing of the season or timing of grazing. Delaying grazing enhanced C uptake by approximately 3 g C m-2 d-1. Advancing spring phenology reduced C uptake by approximately 1.5 g C m-2 d-1, but only when plots were directly warmed by the OTCs; spring advancement did not have a long-term influence on NEE. Consequently, the two strongest drivers of NEE, cloud cover and grazing, can have opposing effects and thus future growing season NEE will depend on the magnitude of change in timing of grazing and incident sunlight. © 2019 The Author(s). Published by IOP Publishing Ltd."
"57211627795;13403622000;57203053066;12040335900;","A positive iris feedback: Insights from climate simulations with temperature-sensitive cloud-rain conversion",2019,"10.1175/JCLI-D-18-0845.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074653563&doi=10.1175%2fJCLI-D-18-0845.1&partnerID=40&md5=7c1a841b1d10593a7a295d0041010c26","Estimates for equilibrium climate sensitivity from current climate models continue to exhibit a large spread, from 2.1 to 4.7 K per carbon dioxide doubling. Recent studies have found that the treatment of precipitation efficiency in deep convective clouds-specifically the conversion rate from cloud condensate to rain Cp-may contribute to the large intermodel spread. It is common for convective parameterization in climate models to carry a constant Cp, although its values are model and resolution dependent. In this study, we investigate how introducing a potential iris feedback, the cloud-climate feedback introduced by parameterizing Cp to increase with surface temperature, affects future climate simulations within a slab ocean configuration of the Community Earth System Model. Progressively stronger dependencies of Cp on temperature unexpectedly increase the equilibrium climate sensitivity monotonically from 3.8 to up to 4.6 K. This positive iris feedback puzzle, in which a reduction in cirrus clouds increases surface temperature, is attributed to changes in the opacity of convectively detrained cirrus. Cirrus clouds reduced largely in ice content and marginally in horizontal coverage, and thus the positive shortwave cloud radiative feedback dominates. The sign of the iris feedback is robust across different cloud macrophysics schemes, which control horizontal cloud cover associated with detrained ice. These results suggest a potentially strong but highly uncertain connection among convective precipitation, detrained anvil cirrus, and the high cloud feedback in a climate forced by increased atmospheric carbon dioxide concentrations. © 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses)."
"57209422031;57207473157;36093295000;55899884100;7401436524;","Performance of CAMS-CSM in Simulating the Shortwave Cloud Radiative Effect over Global Stratus Cloud Regions: Baseline Evaluation and Sensitivity Test",2019,"10.1007/s13351-019-8206-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071442367&doi=10.1007%2fs13351-019-8206-y&partnerID=40&md5=d54f7f2e0b1372ac18b40a878ef633b5","The ability of climate models to correctly reproduce clouds and the radiative effects of clouds is vitally important in climate simulations and projections. In this study, simulations of the shortwave cloud radiative effect (SWCRE) using the Chinese Academy of Meteorological Sciences Climate System Model (CAMS-CSM) are evaluated. The relationships between SWCRE and dynamic-thermodynamic regimes are examined to understand whether the model can simulate realistic processes that are responsible for the generation and maintenance of stratus clouds. Over eastern China, CAMS-CSM well simulates the SWCRE climatological state and stratus cloud distribution. The model captures the strong dependence of SWCRE on the dynamic conditions. Over the marine boundary layer regions, the simulated SWCRE magnitude is weaker than that in the observations due to the lack of low-level stratus clouds in the model. The model fails to simulate the close relationship between SWCRE and local stability over these regions. A sensitivity numerical experiment using a specifically designed parameterization scheme for the stratocumulus cloud cover confirms this assertion. Parameterization schemes that directly depict the relationship between the stratus cloud amount and stability are beneficial for improving the model performance. © 2019, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"57189358034;8882641700;7202145115;55606974300;8511991900;","What Drives the Life Cycle of Tropical Anvil Clouds?",2019,"10.1029/2019MS001736","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072213510&doi=10.1029%2f2019MS001736&partnerID=40&md5=c08a04a1ecf99bf99ca3801555329c07","The net radiative effects of tropical clouds are determined by the evolution of thick, freshly detrained anvil clouds into thin anvil clouds. Thick anvil clouds reduce Earth's energy balance and cool the climate, while thin anvil clouds warm the climate. To determine role of these clouds in climate change we need to understand how interactions of their microphysical and macrophysical properties control their radiative properties. We explore anvil cloud evolution using a cloud-resolving model in three-simulation setups of increasing complexity to disentangle the impacts of the various components of diabatic heating and their interaction with cloud-scale motions. The first phase of evolution and rapid cloud spreading is dominated by latent heating within convective updrafts. After the convective detrainment stops, most of the spreading and thinning of the anvil cloud is driven by cloud radiative processes and latent heating. The combination of radiative cooling at cloud top, latent cooling due to sublimation at cloud base, latent heating due to deposition and radiative heating in between leads to a sandwich-like, cooling-heating-cooling structure. The heating sandwich promotes the development of two within-anvil convective layers and a double cell circulation, dominated by strong outflow at 12-km altitude with inflow above and below. Our study reveals how small-scale processes including convective, microphysical processes, latent and radiative heating interact within the anvil cloud system. The absence or a different representation of only one component results in a significantly different cloud evolution with large impacts on cloud radiative effects. ©2019. The Authors."
"57211622380;16202694600;","Examining Southern Ocean cloud controlling factors on daily time scales and their connections to midlatitude weather systems",2019,"10.1175/JCLI-D-18-0840.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068914859&doi=10.1175%2fJCLI-D-18-0840.1&partnerID=40&md5=3ab9ace3e02dd2365957e614c547e969","Clouds and their associated radiative effects are a large source of uncertainty in global climate models. One region with particularly large model biases in shortwave cloud radiative effects (CRE) is the Southern Ocean. Previous research has shown that many dynamical ''cloud controlling factors'' influence shortwave CRE on monthly time scales and that two important cloud controlling factors over the Southern Ocean are midtropospheric vertical velocity and estimated inversion strength (EIS). Model errors may thus arise from biases in representing cloud controlling factors (atmospheric dynamics) or in representing how clouds respond to those cloud controlling factors (cloud parameterizations), or some combination thereof. This study extends previous work by examining cloud controlling factors over the Southern Ocean on daily time scales in both observations and global climate models. This allows the cloud controlling factors to be examined in the context of transient weather systems. Composites of EIS and midtropospheric vertical velocity are constructed around extratropical cyclones and anticyclones to examine how the different dynamical cloud controlling factors influence shortwave CRE around midlatitude weather systems and to assess how models compare to observations. On average, models tend to produce a realistic cyclone and anticyclone, when compared to observations, in terms of the dynamical cloud controlling factors. The difference between observations and models instead lies in how the models' shortwave CRE respond to the dynamics. In particular, the models' shortwave CRE are too sensitive to perturbations in midtropospheric vertical velocity and, thus, they tend to produce clouds that excessively brighten in the frontal region of the cyclone and excessively dim in the center of the anticyclone. © 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses)."
"7006705919;7401936984;15755995900;8859530100;55688930000;25629055800;22953153500;36856321600;56384704800;7006270084;9434771700;55544607500;57202299549;6701752471;55418728800;57188758598;6701431208;7005920812;15044268700;55802246600;57202522440;7202048112;52464731300;57210671633;6507492100;36876405100;25637373000;35617453500;7102696626;12761052200;55317177900;6603400519;7102450474;8570871900;57209779308;55165863400;24534445300;7402064802;55717074000;7004245252;13007924700;55720018700;","An Overview of the Atmospheric Component of the Energy Exascale Earth System Model",2019,"10.1029/2019MS001629","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068580236&doi=10.1029%2f2019MS001629&partnerID=40&md5=f2b9c692b04e0646e34f11b45b76a5ea","The Energy Exascale Earth System Model Atmosphere Model version 1, the atmospheric component of the Department of Energy's Energy Exascale Earth System Model is described. The model began as a fork of the well-known Community Atmosphere Model, but it has evolved in new ways, and coding, performance, resolution, physical processes (primarily cloud and aerosols formulations), testing and development procedures now differ significantly. Vertical resolution was increased (from 30 to 72 layers), and the model top extended to 60 km (~0.1 hPa). A simple ozone photochemistry predicts stratospheric ozone, and the model now supports increased and more realistic variability in the upper troposphere and stratosphere. An optional improved treatment of light-absorbing particle deposition to snowpack and ice is available, and stronger connections with Earth system biogeochemistry can be used for some science problems. Satellite and ground-based cloud and aerosol simulators were implemented to facilitate evaluation of clouds, aerosols, and aerosol-cloud interactions. Higher horizontal and vertical resolution, increased complexity, and more predicted and transported variables have increased the model computational cost and changed the simulations considerably. These changes required development of alternate strategies for tuning and evaluation as it was not feasible to “brute force” tune the high-resolution configurations, so short-term hindcasts, perturbed parameter ensemble simulations, and regionally refined simulations provided guidance on tuning and parameterization sensitivity to higher resolution. A brief overview of the model and model climate is provided. Model fidelity has generally improved compared to its predecessors and the CMIP5 generation of climate models. ©2019. The Authors."
"7101748780;23037063200;6603730198;35096299800;22953153500;35519286800;6602817609;36056399500;57189297500;55688930000;36931958000;37162453600;57210350827;55618940500;7006705919;9635016300;","E3SMv0-HiLAT: A Modified Climate System Model Targeted for the Study of High-Latitude Processes",2019,"10.1029/2018MS001524","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071139604&doi=10.1029%2f2018MS001524&partnerID=40&md5=ca6199549d9eca83ba7edb330be5d0af","We document the configuration, tuning, and evaluation of a modified version of the Community Earth System Model version 1 (Hurrell et al., 2013, https://doi.org/10.1175/BAMS-D-12), introduced here as E3SMv0-HiLAT, intended for study of high-latitude processes. E3SMv0-HiLAT incorporates changes to the atmospheric model affecting aerosol transport to high northern latitudes and to reduce shortwave cloud bias over the Southern Ocean. An updated sea ice model includes biogeochemistry that is coupled to an extended version of the ocean model's biogechemistry. This enables cloud nucleation to depend on the changing marine emissions of aerosol precursors, which may be expected in scenarios with strongly changing sea ice extent, oceanic stratification and associated nutrient availability, and atmospheric state. An evaluation of the basic preindustrial state of E3SMv0-HiLAT is presented in order to ensure that its climate is adequate to support future experimentation. Additional capability is not achieved without some cost, relative to the extraordinarily well-tuned model from which it was derived. In particular, a reduction of bias in cloud forcing achieved over the Southern Hemisphere also allows for greater Southern Ocean sea ice extent, a tendency that has been partially but not fully alleviated through experimentation and tuning. The most interesting change in the behavior of the model may be its response to greenhouse gas forcing: While the climate sensitivity is found to be essentially unchanged from that of Community Earth System Model version 1, the adjusted radiative forcing has increased from within one standard deviation above that of Coupled Model Intercomparison Project Phase 5 models to nearly two standard deviations. ©2019. The Authors."
"35221494300;","Warm conveyor belts and their role for cloud radiative forcing in the extratropical storm tracks",2019,"10.1175/JCLI-D-18-0802.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074659723&doi=10.1175%2fJCLI-D-18-0802.1&partnerID=40&md5=2d590a251e0babc3a0b7b57e6cd64466","The link between cloud radiative forcing (CRF) and warm conveyor belts (WCBs), which are strongly ascending airstreams in extratropical cyclones, is investigated based on ERA-Interim reanalysis from 1979 to 2011. Clouds associated with WCBs can be liquid, mixed phase, or ice clouds. They interact with the longwave and shortwave radiation in different ways and thus strongly influence Earth's radiative budget in the extratropical storm tracks in a complex way. In this study, WCBs are identified with a Lagrangian method, where WCBs are represented by trajectories that rise at least 600 hPa in 48 h in the vicinity of an extratropical cyclone, and CRF is traced along all WCB trajectories during the considered 30-yr period. The results show that due to the poleward ascent of WCBs, they exhibit negative net cloud forcing (NetCRF) in the southern part of the associated cloud band, whereas in their northern part, NetCRF gets positive due to the lack of sunlight in the winter months. This nonuniform CRF along WCBs from low to high latitudes increases the meridional NetCRF gradient. Furthermore, in their outflow regions in the North Atlantic, where WCBs are mainly associated with ice clouds, WCBs contribute up to 10 W m22 to the global climatological NetCRF maximum in winter. The results highlight the importance of WCBs in modulating the radiative budget in the extratropics. Furthermore, the results emphasize the need for a correct representation of WCBs in climate models to correctly simulate the cloud-circulation coupling. © 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (http://www.ametsoc.org/PUBSReuseLicenses)."
"55894862000;24468968100;","Long-term cloud fraction biases in CMIP5 GCMs over India during monsoon season",2019,"10.1007/s00704-018-02760-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059661907&doi=10.1007%2fs00704-018-02760-1&partnerID=40&md5=8d97f7824a8e2b994d45faa16d7bade8","Using 24 years of cloud fraction (CF) data from the International Satellite Cloud Climatology Project (ISCCP) observations and their corresponding simulators in general circulation models (GCMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5), we have analyzed cloud biases and their role on radiation over the Indian region (65–100° E and 5–40° N) for the monsoon season of June to September. The present study reports the spatial patterns of CFs and their biases in GCMs compared to observations. It is found that the simulated CFs are highly underestimated up to ~ 40%. Mean of total CF from ISCCP observations is 75% with at least 10% difference with simulated CFs. For high-topped clouds, this difference is about 3–4%. Except for high-topped clouds, other cloud types are not simulated realistically by CMIP5 models used in this study. Further, we investigated the individual cloud types classified based on cloud optical depth and cloud top pressure. We found that, in general, individual cloud types are poorly simulated by models, although some (Max Planck Institute Earth System Model, Low Resolution and Hadley Centre Global Environmental Model, version 2, Earth System) models convincingly simulate high-topped thin clouds. To assess the impact of cloud biases on the simulated radiative forcings, we studied shortwave and longwave cloud radiative forcings from CERES (Clouds and the Earth’s Radiant Energy System) observations and CMIP5 GCMs. It is noticed that the spatial patterns of biases in radiative forcings are similar to the patterns of biases in CFs for high-topped clouds, specifically over the oceanic regions. We find that the biases in cloud radiative forcings could potentially be caused due to the inefficacy of CMIP5 models in simulating high-topped anvil clouds (high-topped cirrus/stratocirrus clouds). The present study confirms that the uncertainty in simulating cloud fractions over the Indian region is still a prominent issue to be addressed in general circulation models. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature."
"7404666510;55224879000;7202160985;54080586800;","Projecting impacts of climate change on global terrestrial ecoregions",2019,"10.1016/j.ecolind.2019.04.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063964468&doi=10.1016%2fj.ecolind.2019.04.006&partnerID=40&md5=d8627cf7581b74e50d6bc69f67dda5e9","Terrestrial ecoregions, including critical ecoregions (CEs), vulnerable ecoregions (VEs), and intact ecoregions (IEs) have been used by the World Wildlife Fund (WWF) to classify global biodiversity and are being affected by climate change, which was considered as one of the main threats to biodiversity conservation. However, the impacts of future climate change in shifted means and extremes of temperature, precipitation, and cloud cover under the representative concentration pathways (RCP 2.6, 4.5, and 8.5) on the characteristics of these ecoregions have yet to be fully understood. The present study was designed using a dynamic global vegetation model and both current and future climate scenarios, to investigate the impacts of shifted means and extremes of temperature, precipitation, and cloud cover on five ecological indicators including net primary productivity (NPP), carbon storage, runoff, wildfire risk, and habitat transformation at the ecoregional scale. The analysis was performed for the terrestrial ecoregions as a whole, as well as for specific subsets of CEs, VEs, and IEs. The results showed that future climate scenarios (whether RCP 2.6, 4.5, or 8.5) were estimated to increase the mean NPP, runoff, wildfire risk, and habitat transformation for all ecoregion types, when comparing values for 2071–2100 to the baseline (1971–2000) period. In contrast, the mean carbon storage in the TEWs, VEs, and CEs was estimated to decrease from the baseline to the values under RCP 2.6 and RCP 4.5 and then increase to their largest values under RCP 8.5. The mean carbon storage in the IEs under RCP 8.5 was estimated to remain lower than the baseline period values. Climate change in shifted means and extremes of temperature, precipitation, and cloud cover are generally significant drivers of the variances of NPP, carbon storage, runoff, wildfire risk, and habitat transformation under RCP 2.6, RCP 4.5, and RCP 8.5. The dynamics of the climate change metrics and the five ecological indicators have significant implications for biodiversity conservation in changing climates. © 2019 Elsevier Ltd"
"7102890144;57205497429;6603565405;35737202600;6701835010;7202208382;57210430928;55597313700;57210424390;","Surface-Atmosphere Coupling Scale, the Fate of Water, and Ecophysiological Function in a Brazilian Forest",2019,"10.1029/2019MS001650","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070716775&doi=10.1029%2f2019MS001650&partnerID=40&md5=93be88b4750b7a141f565b6445a041ae","Tropical South America plays a central role in global climate. Bowen ratio teleconnects to circulation and precipitation processes far afield, and the global CO2 growth rate is strongly influenced by carbon cycle processes in South America. However, quantification of basin-wide seasonality of flux partitioning between latent and sensible heat, the response to anomalies around climatic norms, and understanding of the processes and mechanisms that control the carbon cycle remains elusive. Here, we investigate simulated surface-atmosphere interaction at a single site in Brazil, using models with different representations of precipitation and cloud processes, as well as differences in scale of coupling between the surface and atmosphere. We find that the model with parameterized clouds/precipitation has a tendency toward unrealistic perpetual light precipitation, while models with explicit treatment of clouds produce more intense and less frequent rain. Models that couple the surface to the atmosphere on the scale of kilometers, as opposed to tens or hundreds of kilometers, produce even more realistic distributions of rainfall. Rainfall intensity has direct consequences for the “fate of water,” or the pathway that a hydrometeor follows once it interacts with the surface. We find that the model with explicit treatment of cloud processes, coupled to the surface at small scales, is the most realistic when compared to observations. These results have implications for simulations of global climate, as the use of models with explicit (as opposed to parameterized) cloud representations becomes more widespread. ©2019. The Authors."
"57214577353;9743834700;22939703100;6602469213;14421692400;7103246957;57211296807;57211292346;","An analog approach for weather estimation using climate projections and reanalysis data",2019,"10.1175/JAMC-D-18-0255.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073336044&doi=10.1175%2fJAMC-D-18-0255.1&partnerID=40&md5=0a5f461b9b9cb1f0b09250eda5841768","General circulation models (GCMs) are essential for projecting future climate; however, despite the rapid advances in their ability to simulate the climate system at increasing spatial resolution, GCMs cannot capture the local and regional weather dynamics necessary for climate impacts assessments. Temperature and precipitation, for which dense observational records are available, can be bias corrected and downscaled, but many climate impacts models require a larger set of variables such as relative humidity, cloud cover, wind speed and direction, and solar radiation. To address this need, we develop and demonstrate an analog-based approach, which we call a ‘‘weather estimator.’’ The weather estimator employs a highly generalizable structure, utilizing temperature and precipitation from previously downscaled GCMs to select analogs from a reanalysis product, resulting in a complete daily gridded dataset. The resulting dataset, constructed from the selected analogs, contains weather variables needed for impacts modeling that are physically, spatially, and temporally consistent. This approach relies on the weather variables’ correlation with temperature and precipitation, and our correlation analysis indicates that the weather estimator should best estimate evaporation, relative humidity, and cloud cover and do less well in estimating pressure and wind speed and direction. In addition, while the weather estimator has several user-defined parameters, a sensitivity analysis shows that the method is robust to small variations in important model parameters. The weather estimator recreates the historical distributions of relative humidity, pressure, evaporation, shortwave radiation, cloud cover, and wind speed well and outperforms a multiple linear regression estimator across all predictands. © 2019 American Meteorological Society."
"57001165400;56267602600;36093295000;55899884100;55278302200;56097082300;57210847662;57208532600;","Cloud Radiative Feedbacks during the ENSO Cycle Simulated by CAMS-CSM",2019,"10.1007/s13351-019-8104-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071665237&doi=10.1007%2fs13351-019-8104-3&partnerID=40&md5=bbcded52c89cbf8f9c54d03fed106137","This study evaluated the simulated cloud radiative feedbacks (CRF) during the El Nino-Southern Oscillation (ENSO) cycle in the latest version of the Chinese Academy of Meteorological Sciences climate system model (CAMS-CSM). We conducted two experimental model simulations: the Atmospheric Model Intercomparison Project (AMIP), forced by the observed sea surface temperature (SST); and the preindustrial control (PIcontrol), a coupled run without flux correction. We found that both the experiments generally reproduced the observed features of the shortwave and longwave cloud radiative forcing (SWCRF and LWCRF) feedbacks. The AMIP run exhibited better simulation performance in the magnitude and spatial distribution than the PIcontrol run. Furthermore, the simulation biases in SWCRF and LWCRF feedbacks were linked to the biases in the representation of the corresponding total cloud cover and precipitation feedbacks. It is interesting to further find that the simulation bias originating in the atmospheric component was amplified in the PIcontrol run, indicating that the coupling aggravated the simulation bias. Since the PIcontrol run exhibited an apparent mean SST cold bias over the cold tongue, the precipitation response to the SST anomaly (SSTA) changes during the ENSO cycle occurred towards the relatively warmer western equatorial Pacific. Thus, the corresponding cloud cover and CRF shifted westward and showed a weaker magnitude in the PI-control run versus observational data. In contrast, the AMIP run was forced by the observational SST, hence representing a more realistic CRF. Our results demonstrate the challenges of simulating CRF in coupled models. This study also underscores the necessity of realistically representing the climatological mean state when simulating CRF during the ENSO cycle. © 2019, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"6507400558;57210425899;","Toward a Stochastic Relaxation for the Quasi-Equilibrium Theory of Cumulus Parameterization: Multicloud Instability, Multiple Equilibria, and Chaotic Dynamics",2019,"10.1029/2019MS001627","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070700442&doi=10.1029%2f2019MS001627&partnerID=40&md5=c4f8599714fac98434af7c0427dde0d2","The representation of clouds and organized tropical convection remains one of the biggest sources of uncertainties in climate and long-term weather prediction models. Some of the most common cumulus parameterization schemes, namely, mass-flux schemes, rely on the quasi-equilibrium (QE) closure, which assumes that convection consumes the large-scale instability and restores large-scale equilibrium instantaneously. However, the QE hypothesis has been challenged both conceptually and in practice. Subsequently, the QE assumption was relaxed, and instead, prognostic equations for the cloud work function (CWF) and the cumulus kinetic energy (CKE) were derived and used. It was shown that even if the CWF kernel serves to damp the CWF, the prognostic system exhibits damped oscillations on a timescale of a few hours, giving parameterized-cumulus-clouds enough memory to interact with each other, with the environment, and with stratiform anvils in particular. Herein, we show that when cloud-cloud interactions are reintroduced into the CWF-CKE equations, the coupled system becomes unstable. Moreover, we couple the CWF-CKE prognostic equations to dynamical equations for the cloud area fractions, based on the mean field limit of a stochastic multicloud model. Qualitative analysis and numerical simulations show that the CKE-CWF-cloud area fraction equations exhibit interesting dynamics including multiple equilibria, limit cycles, and chaotic behavior both when the large-scale forcing is held fixed and when it oscillates with various frequencies. This is representative of cumulus convection variability, and its capability to transition between various regimes of organization at multiple scales and regimes of scattered convection, in an intermittent and chaotic fashion. ©2019. The Authors."
"57191702441;55801070100;57201075918;57210922931;57210841597;","Simulation Study of Cloud Properties Affected by Heterogeneous Nucleation Using the GRAPES_SCM during the TWP-ICE Campaign",2019,"10.1007/s13351-019-8203-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071699076&doi=10.1007%2fs13351-019-8203-1&partnerID=40&md5=7cff16bd65fb3c188b134862741e8927","This study used the Global/Regional Assimilation and PrEdiction System Single-Column Model (GRAPES_SCM) to simulate monsoon precipitation with deep convective cloud and associated cirrus during the Tropical Warm Pool International Cloud Experiment (TWP-ICE), especially during the active and suppressed monsoon periods. Four cases with different heterogeneous nucleation parameterizations were simulated by using the ensemble method. All simulations clearly separated the active and suppressed monsoon periods, and they reproduced the major characteristics of monsoonal cloud such as the total cloud hydrometeor mixing ratio distribution, and precipitation and radiation properties. The results showed that the number concentration production rate of different heterogeneous nucleation parameterizations varied substantially under the given temperature and water vapor mixing ratio. However, ice formation and precipitation during the monsoon period were affected only slightly by the different heterogeneous nucleation parameterizations. This study also captured clear competition between different ice formation processes. © 2019, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"57191094832;7003908632;16444949400;7006577245;27267529400;57210442642;33068271100;","Simulating Arctic ice clouds during spring using an advanced ice cloud microphysics in the WRF model",2019,"10.3390/atmos10080433","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070739014&doi=10.3390%2fatmos10080433&partnerID=40&md5=33a73d1c99c98ad32270a7555e8dd313","Two Types of Ice Clouds (TICs) have been characterized in the Arctic during the polar night and early spring. TIC-1 are composed by non-precipitating small ice crystals of less than 30 μm in diameter. The second type, TIC-2, are characterized by a low concentration of large precipitating ice crystals (>30 μm). Here, we evaluate the Weather Research and Forecasting (WRF) model performance both in space and time after implementing a parameterization based on a stochastic approach dedicated to the simulation of ice clouds in the Arctic. Well documented reference cases provided us in situ data from the spring of 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) campaign over Alaska. Simulations of the microphysical properties of the TIC-2 clouds on 15 and 25 April 2008 (polluted or acidic cases) and TIC-1 clouds on non-polluted cases are compared to DARDAR (raDAR/liDAR) satellite products. Our results show that the stochastic approach based on the classical nucleation theory, with the appropriate contact angle, is better than the original scheme in WRF model to represent TIC-1 and TIC-2 properties (ice crystal concentration and size) in response to the IN acidification. © 2019 by the authors."
"57191753174;56447586200;57202869313;","The differences in cloud vertical structures between active and break spells of the East Asian summer monsoon based on CloudSat data",2019,"10.1016/j.atmosres.2019.03.035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063317149&doi=10.1016%2fj.atmosres.2019.03.035&partnerID=40&md5=fd9254a675bfff60ba72bc76f3ce4626","The description of the cloud vertical structure remains the key source of uncertainty in climate studies. Based on the CloudSat dataset, the differences in cloud vertical structures between the active and break spells of the East Asian summer monsoon are analyzed by using the composite analysis method. During the active spell, more clouds appear, the occurrence frequency of single-layer clouds significantly decreases, and the occurrence frequency of clouds with two and more layers obviously increases. The lowest layer of the cloud is thicker than the higher layer during the active spell, while the highest layer of the cloud is thicker than the lower layer during the break spell. The clouds in the southern region of the study area are thicker than the clouds in the northern region during the active spell and thinner than the clouds in the northern region during the break spell. From the active spell to the break spell, the clouds became sparser in the southern region but more compact in the northern region. During the active spell, the cloudiness anomaly demonstrates an obvious northward-tilting structure from the upper atmosphere to the lower atmosphere because the large value center of high clouds is located in the south of the study area, while the middle and low-level clouds are located in the center of the study area. Both convective precipitation and stratiform precipitation occur in the southern region during the active spell, while the northern region is mainly dominated by convective precipitation. The cloud ice water content increases during the active spell and decreases during the break spell. During the active spell, the cloud liquid water content (LWC) increases in most of the study area, and the positive LWC anomaly exhibits an apparent northward-tilting structure from the upper level to the lower level. During the break spell, the LWC decreases in the northern region, and the negative anomaly tilts northward from the upper level to the lower level. However, the shallow convective clouds in the southern region are not completely suppressed during the break spell, and abundant positive LWC anomalies are observed in the lower troposphere. © 2019 Elsevier B.V."
"56898331700;57200702127;25227357000;7102018821;7404829395;8511991900;55717074000;55814053500;7005973015;","Ice nucleation by aerosols from anthropogenic pollution",2019,"10.1038/s41561-019-0389-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068543001&doi=10.1038%2fs41561-019-0389-4&partnerID=40&md5=940ff42940587684785883fba1ea343f","The formation of ice particles in the atmosphere strongly affects cloud properties and the climate. While mineral dust is known to be an effective ice nucleating particle, the role of aerosols from anthropogenic pollution in ice nucleation is still under debate. Here we probe the ice nucleation ability of different aerosol types by combining 11-year observations from multiple satellites and cloud-resolving model simulations. We find that, for strong convective systems, the ice particle effective radius near cloud top decreases with increasing loading of polluted continental aerosols, because the ice formation is dominated by homogeneous freezing of cloud droplets, which are smaller under more polluted conditions. By contrast, an increase in ice particle effective radius with polluted continental aerosols is found for moderate convection. Our model simulations suggest that this positive correlation is explained by enhanced heterogeneous ice nucleation and prolonged ice particle growth at higher aerosol loading, indicating that polluted continental aerosols contain a considerable fraction of ice nucleating particles. Similar aerosol–ice relationships are observed for dust aerosols, further corroborating the ice nucleation ability of polluted continental aerosols. By catalysing ice formation, aerosols from anthropogenic pollution could have profound impacts on cloud lifetime and radiative effect as well as precipitation efficiency. © 2019, The Author(s), under exclusive licence to Springer Nature Limited."
"56648203800;36860532100;26534820600;24544731100;7004890737;","Effects of Liquid Clouds on GPS Radio Occultation Profiles in Superrefractions",2019,"10.1029/2019EA000721","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071338029&doi=10.1029%2f2019EA000721&partnerID=40&md5=19841bff6b4fb4ec557f39a8e0af75d2","Inversion of radio occultation (RO) measurements to atmospheric parameters in the neutral atmosphere utilizes the assumption of spherical symmetry by implementation of the Abel transform. The main contribution to the retrieved refractional angle and other geophysical parameters comes from gaseous properties of the atmosphere. The atmospheric refraction is expressed by a function of air pressure, air temperature, and water vapor pressure. Such commonly adopted methodology results in highly comparable RO retrievals with background models. However, in the lowermost troposphere referred to as planetary boundary layer, inversion in spherically symmetric atmosphere is an ill-conditioned problem. The presence of superrefractions introduces negative errors in the RO-retrieved refractivity (N-bias). We show that significant refractivity gradients are frequently collocated with clouds over oceans in tropical and subtropical regions. Based on gridded monthly means we show that superrefractions usually occur at altitudes up to 2 km and the largest cloud fractions tend to suspend at underlying layers. The magnitude of clouds expressed in terms of refractivity units can exceed 1.5, which corresponds to 0.5% in terms of fractional differences. We use both geometrical optics and wave optics techniques to illustrate propagation mechanisms in RO retrievals. Simulation experiments suggest that RO inversions in cloudy planetary boundary layer lead to larger negative N-biases. Low-level clouds retrieved from numerical weather prediction model could therefore be used as an indicator of erroneous RO observations. A better agreement with RO refractivity could be achieved by incorporating cloud variables into background fields especially over the Pacific and Atlantic Oceans. © 2019. The Authors."
"55338948800;8701353900;","Stochastic Differential Equations for the Variability of Atmospheric Convection Fluctuating Around the Equilibrium",2019,"10.1029/2019MS001638","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070915166&doi=10.1029%2f2019MS001638&partnerID=40&md5=9c5e40645a066744c4268dce703657dc","Most convection parameterization schemes used within current atmospheric models make a convective equilibrium assumption, which breaks at the resolutions currently used by many numerical weather prediction models. To account for fluctuations of the cloud base mass flux about its equilibrium value, stochastic convection schemes have been developed for both deep (Plant & Craig, 2008, https://doi.org/10.1175/2007JAS2263.1) and shallow (Sakradzija et al., 2015, https://doi.org/10.5194/npg-22-65-2015) convection. Due to the need to explicitly track individual clouds in each grid box, these schemes can be computationally expensive. Motivated by the above considerations, the present study demonstrates how the machinery of the above schemes can be reduced to the solution of two ordinary stochastic differential equations for the cloud number and the total cloud base mass flux. The properties of the resulting stochastic processes for the cloud number and the total mass flux are not exactly equivalent to those of the original schemes but recover them to a very good approximation. © 2019. The Authors."
"25823927100;","Impact of Cumulus Microphysics and Entrainment Specification on Tropical Cloud and Radiation in GFDL AM2",2019,"10.1007/s41748-019-00099-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067958146&doi=10.1007%2fs41748-019-00099-9&partnerID=40&md5=e143b3e39ec3eb22a0dec72e890a62b8","Clouds and precipitation simulated by climate models still have a large room for improvement. Geophysical Fluid Dynamics Laboratory (GFDL) High-Resolution Atmospheric Model (HiRAM) has much larger ice water path (IWP, ~ 5 times) and stratiform precipitation fraction (~ 10 times) than its Atmospheric Model version 2 (AM2) over the Tropics. It is found that such differences are mainly due to the replacement of the relaxed Arakawa Schubert (RAS) scheme in AM2 by the modified University of Washington (UW) shallow convection used in HiRAM. The focus of the study is to investigate the sensitivity of simulated cloud, precipitation, and radiation to the two key parameters (precipitation efficiency and entrainment specification) in RAS, and interpret the difference between AM2 and HiRAM. With more deep plumes inhibited, the convective heating and moistening decrease, and the upper troposphere becomes colder and drier. With reduced precipitation efficiency, more convective condensate is detrained and stratiform precipitation increases. Both precipitation efficiency and entrainment specification change the vertical heating profiles and precipitation partitioning, but via different mechanisms. Using offline radiation calculations, convection scheme-induced tropical radiation variation is investigated. Increased longwave trapping by increased upper level ice clouds is partially compensated by a dry and cold bias in the upper troposphere. However, top of atmosphere absorbed shortwave reduction is proportional to increased IWP, but the reduction is not as large as that computed using offline radiation calculation assuming similar increase of IWP. The reason is that the increased IWP associated with large-scale precipitation does not peak around noon with the maximum solar radiation as that associated with convective precipitation. The study highlights the importance of convective parameterization in regulating tropical clouds and radiation. © 2019, King Abdulaziz University and Springer Nature Switzerland AG."
"55542833500;57210443121;57210441556;","Comparison of anthropogenic aerosol climate effects among three climate models with reduced complexity",2019,"10.3390/atmos10080456","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070768651&doi=10.3390%2fatmos10080456&partnerID=40&md5=bbddf9df787c78f211e0db0012ed7093","The same prescribed anthropogenic aerosol forcing was implemented into three climate models. The atmosphere components of these participating climate models were the GAMIL, ECHAM, and CAM models. Ensemble simulations were carried out to obtain a reliable estimate of anthropogenic aerosol effective radiative forcing (ERF). The ensemble mean ERFs from these three participating models with this aerosol forcing were -0.27, -0.63, and -0.54 W·m-2. The model diversity in ERF is clearly reduced as compared with those based on the models' own default approaches (-1.98, -0.21, and -2.22 W·m-2. This is consistent with the design of this aerosol forcing. The modeled ERF can be decomposed into two basic components, i.e., the instantaneous radiative forcing (RF) from aerosol-radiation interactions (RFari) and the aerosol-induced changes in cloud forcing (ΔFcloud*). For the three participating models, the model diversity in RFari (-0.21, -0.33, and -0.29 W·m-2 could be constrained by reducing the differences in natural aerosol radiative forcings. However, it was difficult to figure out the reason for the model diversity in ΔFcloud* (-0.05, -0.28, and -0.24 W·m-2), which was the dominant source of the model diversity in ERF. The variability of modeled ERF was also studied. Ensemble simulations showed that the modeled RFs were very stable. The rapid adjustments (ERF - RF) had an important role to play in the quantification of the perturbation of ERF. Fortunately, the contribution from the rapid adjustments to the mean ERF was very small. This study also showed that we should pay attention to the difference between the aerosol climate effects we want and the aerosol climate effects we calculate. © 2019 by the authors."
"55750945600;57209469748;13612429600;55821195600;35147406500;","Precondition cloud algorithm and Copula coupling model-based approach for drought hazard comprehensive assessment",2019,"10.1016/j.ijdrr.2019.101220","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067895783&doi=10.1016%2fj.ijdrr.2019.101220&partnerID=40&md5=a1d18bb6511663961b94e7ee8ea3a20d","Drought is an extreme hydrological event that occurs frequently in many parts of the world due to the influence of climate change and human activity, and it is of significant importance to reasonably quantify the drought hazard to develop effective drought-resistant strategies. Therefore, the primary motivation of this study is to propose an alternative approach for drought hazard assessment which describes the uncertainty of drought hazard system by combining its randomness with fuzziness. Firstly, the joint probability distribution determined by Copulas function is applied to depict the randomness of drought indices, then the fuzzy certainty degree of drought hazard is computed by employing the forward precondition cloud algorithm, and finally, the precondition cloud generator and Copula (PCGC) coupling model-based approach for drought hazard assessment is developed. The application result of PCGC approach in Kunming city, China indicates that, the comprehensive drought hazard level of Kunming city exhibits a slight increasing trend from 1956 to 2011, especially from 1999 to 2011. Moreover, the average probabilities for the occurrence of future drought of level I, II, III, IV, and V in Kunming city are 0.3892, 0.3449, 0.2177, 0.0840 and 0.0028 respectively. Thus it can be seen that the proposed PCGC approach is effective, feasible, and accurate, which can be further applied in drought hazard identification and assessment field. © 2019"
"57204525559;35974264700;21740519000;7005518087;8832722300;6507421222;57202512904;57207760531;","A Path-Tracing Monte Carlo Library for 3-D Radiative Transfer in Highly Resolved Cloudy Atmospheres",2019,"10.1029/2018MS001602","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070681134&doi=10.1029%2f2018MS001602&partnerID=40&md5=9ae2ccdb54f11df6b73a5e26dcf1deca","Interactions between clouds and radiation are at the root of many difficulties in numerically predicting future weather and climate and in retrieving the state of the atmosphere from remote sensing observations. The broad range of issues related to these interactions, and to three-dimensional interactions in particular, has motivated the development of accurate radiative tools able to compute all types of radiative metrics, from monochromatic, local, and directional observables to integrated energetic quantities. Building on this community effort, we present here an open-source library for general use in Monte Carlo algorithms. This library is devoted to the acceleration of ray tracing in complex data, typically high-resolution large-domain grounds and clouds. The main algorithmic advances embedded in the library are related to the construction and traversal of hierarchical grids accelerating the tracing of paths through heterogeneous fields in null-collision (maximum cross-section) algorithms. We show that with these hierarchical grids, the computing time is only weakly sensitive to the refinement of the volumetric data. The library is tested with a rendering algorithm that produces synthetic images of cloud radiances. Other examples of implementation are provided to demonstrate potential uses of the library in the context of 3-D radiation studies and parameterization development, evaluation, and tuning. © 2019. The Authors."
"57210450157;56524152600;15757708600;55382938000;6701712459;7003748648;","Projections of Alpine snow-cover in a high-resolution climate simulation",2019,"10.3390/atmos10080463","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070769324&doi=10.3390%2fatmos10080463&partnerID=40&md5=829a61a1189772aa14cec8e55b862149","The recent development of high-resolution climate models offers a promising approach in improving the simulation of precipitation, clouds and temperature. However, higher grid spacing is also a promising feature to improve the simulation of snow cover. In particular, it provides a refined representation of topography and allows for an explicit simulation of convective precipitation processes. In this study we analyze the snow cover in a set of decade-long high-resolution climate simulation with horizontal grid spacing of 2.2km over the greater Alpine region. Results are compared against observations and lower resolution models (12 and 50 km), which use parameterized convection. The simulations are integrated using the COSMO (Consortium for Small-Scale Modeling) model. The evaluation of snow water equivalent (SWE) in the simulation of present-day climate, driven by the ERA-Interim reanalysis, against an observational dataset, reveals that the high-resolution simulation clearly outperforms simulations with grid spacing of 12 and 50 km. The latter simulations underestimate the cumulative amount of SWE over Switzerland over the whole annual cycle by 33% (12km simulation) and 56% (50km simulation) while the high-resolution simulation shows a spatially and temporally averaged difference of less than 1%. Scenario simulations driven by GCM MPI-ESM-LR (2081-2090 RCP8.5 vs. 1991-2000) reveal a strong decrease of SWE over the Alps, consistent with previous studies. Previous studies had found that the relative decrease becomes gradually smaller with elevation, but this finding was limited to low and intermediate altitudes (as a 12km simulation resolves the topography up to 2500 m). In the current study we find that the height gradient reverses sign, and relative reductions in snow cover increases above 3000m asl, where important parts of the cryosphere are present. In addition, the simulations project a transition from permanent to seasonal snow cover at high altitudes, with potentially important impacts to Alpine permafrost. This transition and the more pronounced decline of SWE emphasize the value of the higher grid spacing. Overall, we show that high-resolution climate models offer a promising approach in improving the simulation of snow cover in Alpine terrain. © 2019 by the authors."
"57217587779;7003754350;55588521800;57217784255;57217590285;","SEASONAL PRECIPITATION SIGNAL in EARLYWOOD and LATEWOOD RING WIDTH CHRONOLOGIES of PINUS ROXBURGHII",2019,"10.3959/1536-1098-75.2.86","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087428398&doi=10.3959%2f1536-1098-75.2.86&partnerID=40&md5=0eb6e486ecab6059eaf4040da4c83df9","The growth response of earlywood and latewood to precipitation in chir pine (Pinus roxburghii) was studied by examining a series of core samples from the Garhwal Himalaya, India. Earlywood and latewood were observed to contribute about equal proportions towards the total ring width. Comparison of tree-ring data with the CRU TS3.22 (land) precipitation dataset indicates that earlywood is positively correlated with spring and early summer precipitation, whereas latewood is negatively correlated with pre-monsoon and early monsoon precipitation. This seasonally-reversed climate signal is confirmed when regional weather station precipitation data were used. A similar seasonally reversed climate response was found in earlywood and latewood of two datasets obtained from core samples from two other sites located in Nepal and Bhutan. Because chir pine is a light-demanding species, light limitation during the monsoon season could be an important factor behind the negative correlation between latewood and precipitation. NOAA NCEP-NCAR low cloud data were used to test this hypothesis, and the preliminary results support the hypothesis; however, further analysis will be needed to fully validate this hypothesis. © 2019 by the Tree-Ring Society."
"35847990900;55934848500;57203216640;57149502600;","A Global Perspective on Local Meteoric Water Lines: Meta-analytic Insight Into Fundamental Controls and Practical Constraints",2019,"10.1029/2019WR025181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070806735&doi=10.1029%2f2019WR025181&partnerID=40&md5=45d1224e569b80b910849b852cdc5a60","Local meteoric water lines (LMWLs) represent the site-specific long-term covariation of hydrogen and oxygen stable isotope ratios. LMWLs have practical utility as a hydrologic framework and as benchmarks for evaluating hydroclimatic processes in isotope-enabled climate models. In this manuscript, we characterize the global distribution of LMWLs and compare them to LMWLs from model data. To evaluate the sensitivity of the covariance of stable isotope ratios to data set length, we paired time series rarifaction with Bayesian ellipse estimation. We then applied a threshold of 48 months and estimated LMWLs at 398 sites in 25 Köppen climate classes using orthogonal distance regression. Slopes ranged from 4.8 to 10.9, with an average of 7.64 ± 0.64. Intercepts ranged from −24‰ to 27‰, with an average of 6.85 ± 6.2‰. We identified three processes: (1) subcloud evaporation of rain, (2) atmospheric remoistening by rainfall evaporation, and (3) conditions of snow formation as important controls on slopes and intercepts in arid, humid, and seasonally snowy regions, respectively. We compared observational LMWLs with those from a suite of isotope-enabled climate models. At arid and snowy sites, model data produced higher slopes and intercepts than observational data. At humid sites, model data exhibited dampened variability in slopes and intercepts relative to observational data. These results indicate potential for improvement in the precipitation and/or isotope parameterizations of raindrop evaporation, advection of reevaporated water, evapotranspiration fractionation, and supersaturation in mixed-phase clouds. This meta-analysis demonstrates LMWLs utility for identifying specific hydroclimatic and isotopic processes in observations and models. © 2019. American Geophysical Union. All Rights Reserved."
"57194946836;7404438747;56424145700;","Warm bias of sea surface temperature in Eastern boundary current regions—a study of effects of horizontal resolution in CESM",2019,"10.1007/s10236-019-01280-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068860153&doi=10.1007%2fs10236-019-01280-4&partnerID=40&md5=75cf103909f9b82b275ae861a38094eb","Warm bias of modeled sea surface temperature (SST) in the eastern boundary upwelling systems (EBUS) is a ubiquitous feature in coupled climate models. This paper investigates the causes underlying this warm bias, with a focus on the effect of horizontal resolution in the atmospheric component of coupled models, by using Community Earth System Model (CESM) as an example. By breaking down the energy budget of the upper ocean, we conclude that surface net heat flux and Ekman upwelling process exert a considerable influence (over 80%) on upper ocean temperature of EBUS in CESM. Besides, the problem of underestimation of stratocumulus cloud is not present near the coast, and hence not responsible for this warm bias in CESM. On the contrary, downward shortwave radiation bias is overcompensated by longwave radiation and latent flux bias on the open ocean. Therefore, the insufficient ocean dynamic upwelling is the dominantly cause for SST warm bias. Finer horizontal resolution atmosphere component of CESM enables better representation of low-level coastal jet structure, with stronger and closer alongshore wind stress and curl leading to realistic representation of upwelling process and horizontal water mass transportation. Furthermore, low-level coastal jet is shown to be sensitive to coastal mountain topography, especially in South East Pacific region, through both thermodynamic and dynamic atmospheric processes and oceanic response. This article provides further proof of improving coupled climate models in reducing the SST biases in EBUS regions. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"55857969100;7102859255;7005265210;","A deficit of seasonal temperature forecast skill over west coast regions in NMME",2019,"10.1175/WAF-D-18-0172.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073391123&doi=10.1175%2fWAF-D-18-0172.1&partnerID=40&md5=441652914f2120d8b39d98334158b9a3","This study investigates the forecast skill of seasonal-mean near-surface (2 m) air temperature in the North American Multimodel Ensemble (NMME) Phase 2, with a focus on the West Coast of the United States. Overall, 1-month lead time NMME forecasts exhibit skill superior or similar to persistence forecasts over many continental regions, and skill is generally higher over the ocean than the continent. However, forecast skill along most West Coast regions is markedly lower than in the adjacent ocean and interior, especially during the warm seasons. Results indicate that the poor forecast skill along the West Coast of the United States reflects deficiencies in their representation of multiple relevant physical processes. Analyses focusing on California find that summer forecast errors are spatially coherent over the coastal region and the inland region individually, but the correlation of forecast errors between the two regions is low. Variation in forecast performance over the coastal California region is associated with anomalous geopotential height over the lower middle latitudes and subtropics of the eastern Pacific, North America, and the western Atlantic. In contrast, variation in forecast performance over the inland California region is associated with the atmospheric circulation over the western United States. Further, it is found that forecast errors along the California coast are linked to anomalies of low cloudiness (stratus clouds) along the coastal region. © 2019 American Meteorological Society."
"55913339000;57201392422;8370830700;57208532494;57208528783;","Distribution, source and transport of the aerosols over Central Asia",2019,"10.1016/j.atmosenv.2019.04.052","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065024709&doi=10.1016%2fj.atmosenv.2019.04.052&partnerID=40&md5=8e5cc533d68cce7e52ddea78f4fe467b","Limited by scarce observations, the sources and transport of aerosols over Central Asia are relatively unclear. In this study, using Terra and Aqua satellite images, Moderate Resolution Imaging Spectroradiometer (MODIS) data, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite observations and meteorological reanalyze data, the distribution, source and transport of aerosols over Central Asia are investigated. We find that there are 227 aerosol events occurred in Central Asia during 2000–2017 and the aerosols which can be transported from outside to Central Asia are dominated by dust and smoke (organic carbon and black carbon) particles. Statistical analyses show that the contribution of the sources outside of Central Asia (76 times) to all aerosol events (122 times) is greater than that of local emissions in Central Asia (46 times) in the spring and summer during 2000–2017. The smoke events (39 times), sourcing from Russia and Europe with strong northwest wind, account for 51.3% of total aerosol events contributed by sources outside of Central Asia. Additionally, the dust events (37 times), which mainly source from the northern Arabia Peninsula and North Africa with strong southwest wind, account for 48.7% of the total aerosol events contributed by the sources outside of Central Asia. On the contrary, the contribution of local emissions in Central Asia (90 times) to all aerosol events (105 times) is greater than that of outside sources (15 times) in the autumn and winter. Result of clustering analyses for all 157 aerosol events during 2005–2017 is in agreement with the conclusion of statistical analyses based on observations. This study can provide some evidence to understand the aerosol properties over the Central Asia. © 2019 Elsevier Ltd"
"56267602600;57001165400;","ENSO Asymmetry in the CAMS-CSM",2019,"10.1007/s13143-018-00102-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060513591&doi=10.1007%2fs13143-018-00102-9&partnerID=40&md5=d87c70a3af78d72c06972198273d4533","This study presents an overview of El Niño-Southern Oscillation (ENSO) asymmetry using the Chinese Academy of Meteorological Sciences climate system model (CAMS-CSM). We discover that the coupled run of the CAMS-CSM has an obvious bias of ENSO opposite-sign asymmetry compared to observation, mainly in the eastern Pacific. Further analysis shows that the spatial distributions of sea surface temperature anomalies (SSTA) during both phases of the ENSO present individual biases, consisting of a warmer field during the warm phase and a colder field during the cold phase, in comparison with observation. The bias of ENSO asymmetry during both phases is partly due to the unrealistic simulation of shortwave (SW) radiation flux and the corresponding total cloud cover (TCC). The Atmospheric Model Intercomparison Project (AMIP) run demonstrates that biases of the SW radiation flux and the associated TCC originate in the atmospheric component of the model, which could be attributed to its unrealistic cloud microphysical scheme. Through air-sea interaction, these biases are amplified significantly during both ENSO phases of the coupled run. Moreover, another cause for the bias of ENSO asymmetry during the warm phase is the relatively slow decay of the ENSO in the simulation, with the thermocline anomalies propagating eastward more slowly. The bias of ENSO asymmetry in the cold phase is attributed to oceanic internal dynamic advection, mainly associated with zonal and meridional terms. Further analysis also highlights the essential role of reasonably representing the climatological mean state in ENSO model simulation. © 2019, Korean Meteorological Society and Springer Nature B.V."
"57193528525;16837735900;7005911418;","Evaluation of cumulus and microphysics parameterizations in WRF across the convective gray zone",2019,"10.1175/WAF-D-18-0178.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072246127&doi=10.1175%2fWAF-D-18-0178.1&partnerID=40&md5=2bece9912b9de469443d5d719fe4de69","This study evaluates the grid-length dependency of the Weather Research and Forecasting (WRF) Model precipitation performance for two cases in the Southern Great Plains of the United States. The aim is to investigate the ability of different cumulus and microphysics parameterization schemes to represent precipitation processes throughout the transition between parameterized and resolved convective scales (e.g., the gray zone). The cases include the following: 1) a mesoscale convective system causing intense local precipitation, and 2) a frontal passage with light but continuous rainfall. The choice of cumulus parameterization appears to be a crucial differentiator in convective development and resulting precipitation patterns in the WRF simulations. Different microphysics schemes produce very similar outcomes, yet some of the more sophis-ticated schemes have substantially longer run times. This suggests that this additional computational expense does not necessarily provide meaningful forecast improvements, and those looking to run such schemes should perform their own evaluation to determine if this expense is warranted for their application. The best performing cumulus scheme overall for the two cases studies here was the scale-aware Grell–Freitas cumulus scheme. It was able to reproduce a smooth transition from subgrid-(cumulus) to resolved-scale (micro-physics) precipitation with increasing resolution. It also produced the smallest errors for the convective event, outperforming the other cumulus schemes in predicting the timing and intensity of the precipitation. © 2019 American Meteorological Society."
"57204573288;57218444105;36627352900;57204572626;57204571902;35790967600;24386032700;55604938200;","Evaluation of Bayesian multimodel estimation in surface incident shortwave radiation simulation over high latitude areas",2019,"10.3390/rs11151776","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070464523&doi=10.3390%2frs11151776&partnerID=40&md5=bc810b8a788717337bcc61ca70e02bbe","Surface incident shortwave radiation (SSR) is crucial for understanding the Earth's climate change issues. Simulations from general circulation models (GCMs) are one of the most practical ways to produce long-term global SSR products. Although previous studies have comprehensively assessed the performance of the GCMs in simulating SSR globally or regionally, studies assessing the performance of these models over high-latitude areas are sparse. This study evaluated and intercompared the SSR simulations of 48 GCMs participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) using quality-controlled SSR surface measurements at 44 radiation sites from three observation networks (GC-NET, BSRN, and GEBA) and the SSR retrievals from the Clouds and the Earth's Radiant Energy System, Energy Balanced and Filled (CERES EBAF) data set over high-latitude areas from 2000 to 2005. Furthermore, this study evaluated the performance of the SSR estimations of two multimodel ensemble methods, i.e., the simple model averaging (SMA) and the Bayesian model averaging (BMA) methods. The seasonal performance of the SSR estimations of individual GCMs, the SMA method, and the BMA method were also intercompared. The evaluation results indicated that there were large deficiencies in the performance of the individual GCMs in simulating SSR, and these GCM SSR simulations did not show a tendency to overestimate the SSR over high-latitude areas. Moreover, the ensemble SSR estimations generated by the SMA and BMA methods were superior to all individual GCM SSR simulations over high-latitude areas, and the estimations of the BMA method were the best compared to individual GCM simulations and the SMA method-based estimations. Compared to the CERES EBAF SSR retrievals, the uncertainties of the SSR estimations of the GCMs, the SMA method, and the BMA method are relatively large during summer. © 2019 by the authors."
"57208906115;7102878303;","Automatic feature selection and weighting for the formation of homogeneous groups for regional IDF estimation",2019,"10.1016/j.jhydrol.2019.05.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066098988&doi=10.1016%2fj.jhydrol.2019.05.015&partnerID=40&md5=045dd52c9a1d4b2a3da02c46bff61fcb","The intensity-duration frequency (IDF) curve has been used as an effective tool to quantify the risk associated with the impact of extreme rainfall on civil infrastructure. However, recent changes in the rainfall climatology caused by climate change and urbanization have made estimates in the stationary environment provided by the traditional regional IDF approach increasingly inaccurate. This inaccuracy is mainly caused by the lack of consideration for the temporal and spatial differences in the selection of similarity indicators (attributes that are used to measure similarity of extreme rainfall patterns among different stations), resulting in ineffective formation of homogeneous groups (group of stations that share similar extreme rainfall patterns) at various regions. To consider the temporal differences of similarity indicators, including meteorological factors, topographic features and urban impact indicators, a three-layer design is proposed based on the three stages in extreme rainfall formation: cloud formation, rainfall generation and change of rainfall intensity over an urban surface. During the process, the impacts from climate change and urbanization on extreme rainfall patterns are considered through the inclusion of potential features that relate to the rainfall mechanism at each layer. The spatial differences of similarity indicators for Homogeneous Group Formation (HGF) at various regions is resolved by using an automatic feature selection and weighting algorithm, specifically the hybrid searching algorithm of Tabu Search, Lagrange Multiplier and Fuzzy C-means clustering, to select the optimal combination of features for HGF based on the uncertainty in the regional estimates of the rainfall quantiles for a specific site. The proposed methodology fills the gap of including the urbanization impacts on the extreme rainfall patterns during HGF process and challenges the traditional assumption that the same set of features can be equally effective in generating the optimal homogeneous group in regions with different geographic and meteorological characteristics. © 2019 Elsevier B.V."
"15834230600;55894037900;56823556300;23011735800;24069901800;","Columnar aerosol measurements in a continental southeastern Europe site: climatology and trends",2019,"10.1007/s00704-019-02805-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061503914&doi=10.1007%2fs00704-019-02805-z&partnerID=40&md5=3dd4dfb1a73224d26b27ba44db8a70ca","Monitoring of aerosols and their temporal evolution is very important for climate and air quality studies. In this study, we present a climatology of aerosol optical and microphysical properties over a continental southeastern European area based on 9 years of observations from a Cimel sun-photometer operating at Magurele (Romania) in the framework of AErosol RObotic NETwork (AERONET). The site is characterized by high intra-annual and inter-annual variability of the total aerosol optical depth (AOD), which has two peaks, during March and August. For half year, from May to November, Magurele is affected by the transport of aerosols from the nearby city of Bucharest, since the dominant winds are from this direction. Thus, the predominant is the fine mode of aerosols. The high inter-annual and intra-annual variability of Angstrom exponent (440–870 nm) indicates the presence of aerosols of different sizes. Negative statistically significant trends at all AOD wavelengths, the order of 20–40% per decade, have been calculated for the 9-year period of study (2007–2016). These trends are mostly attributed to the reduction of the fine mode particles, showing that the implementation of the EU regulations for the decrease of particulate matter emissions in Bucharest has been beneficial. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature."
"57205646273;8839231800;","Combined Effects of Blocking and AO on a Prolonged Snowstorm in Jeju Island",2019,"10.1007/s13143-018-0088-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060953417&doi=10.1007%2fs13143-018-0088-x&partnerID=40&md5=9f6b9e89ea155d348e01f8beea410c9f","An analysis of the snowstorm that occurred during January 23–25, 2016 in Jeju Island is presented. This event was considered part of the snowfall pattern that rarely occurs at Jeju Island due to the mild marine climate. In terms of diabatic heating, there are two factors encompassing convection and large-scale condensation. One heating factor was the convective instability due to cold advection at the upper level that was 1.7 times stronger than the continuous cold advection at the lower level. The other heating factor was the latent heat emitted by cloud developed by the instability. In the context of large-scale environment, the result of vertical temperature differential was due to the transition to the strong negative Arctic Oscillation (AO) in January 2016. Under the negative AO phase, blocking tilted to the southeast, compared to normal, occurred in the upper layers. Simultaneously, a trough with a core temperature of −45 °C was rapidly induced over the Korean Peninsula. In this study, the snowstorm occurred with a sea surface temperature 1–2 K higher than normal over the Yellow Sea, and cold advection to lower layers was persistent. Therefore, the snowstorm has not been resolved through consideration of the local instability. A maximum of 12 cm of fresh snow cover was recorded during this snowstorm, which persisted for 3 days due to the impact on its large-scale environment, which generated a strong vertical cold advection differential through the occurrence blocking during January 19–24, 2016, under the strong negative AO phase. © 2019, Korean Meteorological Society and Springer Nature B.V."
"42660997900;14324150200;57192438848;7005922032;","Hot days and tropical nights in Nigeria: trends and associated large-scale features",2019,"10.1007/s00704-018-2713-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057948872&doi=10.1007%2fs00704-018-2713-0&partnerID=40&md5=6d96773d45f3378d509085b810da84ce","The impact on society of extreme temperature events is enormous. This study examines the temporal evolution and trends in mean temperatures (minimum temperature, TN; and maximum temperature, TX) and warm extremes in Nigeria as well as in three regions in Nigeria (Guinea, Savanna, and Sahel) using homogenized daily TN and TX for the period 1971–2012. Warm extremes are defined as days with TX > 35 °C (HotD) and nights with TN > 20 °C (TropN). The modified Mann–Kendall test is used to calculate and assess the statistical significance of trends in the indices. The results at annual and seasonal (JFM, AMJ, JAS, and OND) timescales indicate a significant positive increase in temperatures in Nigeria. The warming in annual and seasonal TN is greater than in TX. The temporal evolution in warm extremes is similar to those of the mean temperatures, with trends in TropN greater than those of the HotD. In all the regions, the temporal patterns of trends in mean temperatures and warm extremes are similar. The indices are characterized by positive trends, with the exception of HotD in Guinea with no data during JAS. Analysis of large-scale atmospheric fields during warm extreme days when both TX and TN exceed their respective 90th percentile thresholds shows that warm extreme days are associated with mid-tropospheric subsidence motion in vertical velocity anomaly that is connected with the core of the thermal low and the net convergent flow. These features are accompanied by positive surface shortwave radiation anomaly coupled with cloud cover reduction. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature."
"57201118700;35119688900;35423103700;55703823500;7201785152;57208747715;","Different effects of two ENSO types on arctic surface temperature in boreal winter",2019,"10.1175/JCLI-D-18-0761.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074645113&doi=10.1175%2fJCLI-D-18-0761.1&partnerID=40&md5=7d2a55a21908a144ba7b15ecdfcdf26a","The present work investigates different responses of Arctic surface air temperature (SAT) to two ENSO types based on reanalysis datasets and model experiments. We find that eastern Pacific (EP) ENSO events are accompanied by statistically significant SAT responses over the Barents–Kara Seas in February, while central Pacific (CP) events coincide with statistically significant SAT responses over northeastern Canada and Greenland. These impacts are largely of opposite sign for ENSO warm and cold phases. During EP El Niño in February, the enhanced tropospheric polar vortex over Eurasia and associated local low-level northeasterly anomalies over the Barents–Kara Seas lead to anomalously cold SAT in this region. Simultaneously, the enhanced tropospheric polar vortex leads to enhanced sinking air motion and consequently reduced cloud cover. This in turn reduces downward infrared radiation (IR), which further reduces SAT in the Barents–Kara Seas region. Such a robust response cannot be detected during other winter months for EP ENSO events. During CP El Niño, the February SATs over northeastern Canada and Greenland are anomalously warm and coincide with a weakened tropospheric polar vortex and related local low-level southwesterly anomalies originating from the Atlantic Ocean. The anomalous warmth can be enhanced by the local positive feedback. Similar SAT signals as in February during CP ENSO events can also be seen in January, but they are less statistically robust. We demonstrate that these contrasting Arctic February SAT responses are consistent with responses to the two ENSO types with a series of atmospheric general circulation model experiments. These results have implications for the seasonal predictability of regional Arctic SAT anomalies. © 2019 American Meteorological Society."
"57196237174;57213029726;55939316400;22978775000;57200009259;","Intercomparison of remote-sensing based evapotranspiration algorithms over amazonian forests",2019,"10.1016/j.jag.2019.04.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068642468&doi=10.1016%2fj.jag.2019.04.009&partnerID=40&md5=8f7250d7a5974939a67741f4eededaab","Evapotranspiration (ET) is considered a key variable in the understanding of the Amazonian tropical forests and their response to climate change. Remote-Sensing (RS) based evapotranspiration models are presented as a feasible means in order to provide accurate spatially-distributed ET estimates over this region. In this work, the performance of four commonly used ET RS models was evaluated over Amazonia using Moderate Resolution Imaging Spectroradiometer (MODIS) data. RS models included i) Priestley-Taylor Jet Propulsion Laboratory (PT-JPL), ii) Penman-Monteith MODIS operative parametrization (PM-Mu), iii) Surface Energy Balance System (SEBS), and iv) Satellite Application Facility on Land Surface Analysis (LSASAF). These models were forced using two ancillary meteorological data sources: i) in-situ data extracted from Large-Scale Biosphere-Atmosphere Experiment (LBA) stations (scenario I), and ii) three reanalysis datasets (scenario II), including Modern-Era Retrospective analysis for Research and Application (MERRA-2), European Centre for Medium-range Weather Forecasts (ECMWF) Re-Analysis-Interim (ERA-Interim), and Global Land Assimilation System (GLDAS-2). Performance of algorithms under the two scenarios was validated using in-situ eddy-covariance measurements. For scenario I, PT-JPL provided the best agreement with in-situ ET observations (RMSE = 0.55 mm/day, R = 0.88). Neglecting water canopy evaporation resulted in an underestimation of ET measurements for LSASAF. SEBS performance was similar to that of PT-JPL, nevertheless SEBS estimates were limited by the continuous cloud cover of the region. A physically-based ET gap-filling method was used in order to alleviate this issue. PM-Mu tended to overestimate in-situ ET observations. For scenario II, quality assessment of reanalysis input data demonstrated that MERRA-2, ERA-Interim and GLDAS-2 contain biases that impact model performance. In particular, biases in radiation inputs were found the main responsible of the observed biases in ET estimates. For the region, MERRA-2 tends to overestimate daily net radiation and incoming solar radiation. ERA-Interim tends to underestimate both variables, and GLDAS tends to overestimate daily radiation while underestimating incoming solar radiation. Discrepancies amongst these reanalysis inputs generally explain the observed discrepancies in model spatial and temporal patterns. © 2019 Elsevier B.V."
"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)."
"57196077289;","Identifying alternative wetting and drying (AWD) adoption in the Vietnamese Mekong River delta: A change detection approach",2019,"10.3390/ijgi8070312","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069552819&doi=10.3390%2fijgi8070312&partnerID=40&md5=01f0010769122b2a51022c18def2a401","Alternative wetting and drying (AWD) is an increasingly popular water-saving practice in rice production in the Vietnamese Mekong River Delta, especially considering the impact of projected climate change and reduced water availability. Unfortunately, it is very difficult to determine adoption without deploying thousands of costly household surveys. This research used European Space Agency Sentinel-1a and 1b radar data, combined with in-situ moisture readings, to determine AWD adoption through change detection of a time series wetness index (WI). By using a beta coefficient of the radar data, the WI avoided the pitfalls of cloud cover, surface roughness, and vegetative interference that arise from the sigma coefficient data. The analysis illustrated an AWD adoption likelihood scale across the delta and it showed potential for the use of remotely sensed data to detect adoption. Trends across the Vietnamese delta showed higher adoption rates inland, with lower adoption of AWD in the coastal provinces. These results were supported by a simultaneous effort to collect household level adoption data as part of the same project. However, correlation between the WI values and in situ soil moisture meter readings were most accurate in alluvial soils, illustrating a particularly strong relationship between soil type and WI model robustness. The research suggests that future change detection efforts should focus on retrieving a multi-season dataset and employing a power density analysis on the time series data to fully understand the periodicity of dry down patterns. © 2019 by the author."
"55537426400;57210177151;","The relevance of mid-Holocene Arctic warming to the future",2019,"10.5194/cp-15-1375-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069756282&doi=10.5194%2fcp-15-1375-2019&partnerID=40&md5=a491c1a86f52ddded833badfc0e5f4df","There remain substantial uncertainties in future projections of Arctic climate change. There is a potential to constrain these uncertainties using a combination of paleoclimate simulations and proxy data, but such a constraint must be accompanied by physical understanding on the connection between past and future simulations. Here, we examine the relevance of an Arctic warming mechanism in the mid-Holocene (MH) to the future with emphasis on process understanding. We conducted a surface energy balance analysis on 10 atmosphere and ocean general circulation models under the MH and future Representative Concentration Pathway (RCP) 4.5 scenario forcings. It is found that many of the dominant processes that amplify Arctic warming over the ocean from late autumn to early winter are common between the two periods, despite the difference in the source of the forcing (insolation vs. greenhouse gases). The positive albedo feedback in summer results in an increase in oceanic heat release in the colder season when the atmospheric stratification is strong, and an increased greenhouse effect from clouds helps amplify the warming during the season with small insolation. The seasonal progress was elucidated by the decomposition of the factors associated with sea surface temperature, ice concentration, and ice surface temperature changes. We also quantified the contribution of individual components to the inter-model variance in the surface temperature changes. The downward clear-sky longwave radiation is one of major contributors to the model spread throughout the year. Other controlling terms for the model spread vary with the season, but they are similar between the MH and the future in each season. This result suggests that the MH Arctic change may not be analogous to the future in some seasons when the temperature response differs, but it is still useful to constrain the model spread in the future Arctic projection. The cross-model correlation suggests that the feedbacks in preceding seasons should not be overlooked when determining constraints, particularly summer sea ice cover for the constraint of autumn-winter surface temperature response. © Author(s) 2019."
"56061814400;6602137800;7005007661;7005035762;7101707186;57126848900;57205989730;7003729315;13403957300;35232912700;57213358341;15047918700;55372899300;55717441600;56028554400;57193334794;57202922977;7003359002;37094057400;22635999400;27868213600;56888217500;","Intercomparison of biomass burning aerosol optical properties from in situ and remote-sensing instruments in ORACLES-2016",2019,"10.5194/acp-19-9181-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068462495&doi=10.5194%2facp-19-9181-2019&partnerID=40&md5=f5a0f35dbb975692b8b99f9541ddfea0","The total effect of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in anthropogenic radiative forcing on the climate. Correct characterization of intensive aerosol optical properties, particularly in conditions where absorbing aerosol is present, is a crucial factor in quantifying these effects. The southeast Atlantic Ocean (SEA), with seasonal biomass burning smoke plumes overlying and mixing with a persistent stratocumulus cloud deck, offers an excellent natural laboratory to make the observations necessary to understand the complexities of aerosol-cloud-radiation interactions. The first field deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign was conducted in September of 2016 out of Walvis Bay, Namibia. Data collected during ORACLES-2016 are used to derive aerosol properties from an unprecedented number of simultaneous measurement techniques over this region. Here, we present results from six of the eight independent instruments or instrument combinations, all applied to measure or retrieve aerosol absorption and single-scattering albedo. Most but not all of the biomass burning aerosol was located in the free troposphere, in relative humidities typically ranging up to 60 %. We present the single-scattering albedo (SSA), absorbing and total aerosol optical depth (AAOD and AOD), and absorption, scattering, and extinction Ångström exponents (AAE, SAE, and EAE, respectively) for specific case studies looking at near-coincident and near-colocated measurements from multiple instruments, and SSAs for the broader campaign average over the month-long deployment. For the case studies, we find that SSA agrees within the measurement uncertainties between multiple instruments, though, over all cases, there is no strong correlation between values reported by one instrument and another. We also find that agreement between the instruments is more robust at higher aerosol loading (AOD400 > 0:4). The campaign-wide average and range shows differences in the values measured by each instrument. We find the ORACLES-2016 campaign-average SSA at 500 nm (SSA500) to be between 0.85 and 0.88, depending on the instrument considered (4STAR, AirMSPI, or in situ measurements), with the interquartile ranges for all instruments between 0.83 and 0.89. This is consistent with previous September values reported over the region (between 0.84 and 0.90 for SSA at 550nm). The results suggest that the differences observed in the campaign-average values may be dominated by instrument-specific spatial sampling differences and the natural physical variability in aerosol conditions over the SEA, rather than fundamental methodological differences. © 2019 Author(s)."
"57201667638;23095483400;57203053317;","Elucidating ice formation pathways in the aerosol-climate model ECHAM6-HAM2",2019,"10.5194/acp-19-9061-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069226042&doi=10.5194%2facp-19-9061-2019&partnerID=40&md5=cceec2f79cd6e90886f103e69207a441","Cloud microphysics schemes in global climate models have long suffered from a lack of reliable satellite observations of cloud ice. At the same time there is a broad consensus that the correct simulation of cloud phase is imperative for a reliable assessment of Earth's climate sensitivity. At the core of this problem is understanding the causes for the inter-model spread of the predicted cloud phase partitioning. This work introduces a new method to build a sound cause-and-effect relation between the microphysical parameterizations employed in our model and the resulting cloud field by analysing ice formation pathways. We find that freezing processes in supercooled liquid clouds only dominate ice formation in roughly 6 % of the simulated clouds, a small fraction compared to roughly 63 % of the clouds governed by freezing in the cirrus temperature regime below -35 ĝC. This pathway analysis further reveals that even in the mixed-phase temperature regime between -35 and 0 ĝC, the dominant source of ice is the sedimentation of ice crystals that originated in the cirrus regime. The simulated fraction of ice cloud to total cloud amount in our model is lower than that reported by the CALIPSO-GOCCP satellite product. This is most likely caused by structural differences of the cloud and aerosol fields in our model rather than the microphysical parametrizations employed. © 2019."
"16202694600;8866821900;35767566800;57212416832;","Investigating the Influence of Cloud Radiative Effects on the Extratropical Storm Tracks",2019,"10.1029/2019GL083542","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068920857&doi=10.1029%2f2019GL083542&partnerID=40&md5=b8acc593334837a3bca5bd8b5611b548","Recent studies have focused on the role of cloud radiative effects (CRE) in governing the mean atmospheric circulation and its response to climate change. This study instead examines the role of CRE in climate variability in the extratropics. Cloud locking experiments are performed using the Community Earth System Model. In these experiments, CRE are scrambled, such that they maintain the same climatology but no longer match the model's dynamical fields. The results of these experiments indicate that high-frequency interactions between CRE and dynamics have a small (≤5–10%) but statistically significant damping effect on the intensity of the extratropical storm tracks, particularly in the Southern Hemisphere. Individual midlatitude cyclones have decreased intensity and shorter lifetime. These effects arise largely from clouds' radiative modification of static stability below 700 hPa. The coupling among clouds, radiation, and dynamics thus has a modest but potentially important influence on the extratropical storm tracks. ©2019. American Geophysical Union. All Rights Reserved."
"57207486814;12645767500;57203722524;7101959253;57203030873;","When Will Spaceborne Cloud Radar Detect Upward Shifts in Cloud Heights?",2019,"10.1029/2018JD030242","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068682942&doi=10.1029%2f2018JD030242&partnerID=40&md5=c2ee56b46219485a0843e01dba8d49d0","Cloud feedbacks remain the largest source of uncertainty in future climate predictions. Simulations robustly project an increase in cloud height, which is supported by some observational evidence. However, how much of this increasing trend is due to climate warming and how much is due to multiyear natural variability still remains unclear because of the brevity of existing observational records. Here we estimate when the signal will become detectable at 95% confidence by existing radar technology. We use output from a Representative Concentration Pathway 8.5 Community Earth System Model version 1 simulation in a Monte Carlo analysis to determine (1) what is the first year at which changes in the altitude of high cloud can be confidently estimated if we continue to fly W-band cloud radar, (2) what radar sensitivity is required to detect those changes, and (3) at what latitude will we first detect these changes? In Community Earth System Model version 1 a cloud radar record would be able to confidently detect upward shifts in cloud height over 20–60°N before 2030 for a radar with a sensitivity of −15 dBZ and stable calibration errors of ±0.25 dBZ. Furthermore, vertical resolution could be degraded to 1.6 km with little effect on detection year. Results are more sensitive to the magnitude of calibration errors than to the minimum detectable echo. Our earlier midlatitude detection contrasts with a previous lidar-based analysis, which may be due to radar detecting different parts of the clouds and our use of simulations that account for changing geographical patterns of forced warming through time. ©2019. American Geophysical Union. All Rights Reserved."
"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."
"55747201700;56032594900;6603423022;26422803600;55324559500;7003510880;57194589938;56387519900;57219630787;","Low-level stratiform clouds and dynamical features observed within the southern West African monsoon",2019,"10.5194/acp-19-8979-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069187636&doi=10.5194%2facp-19-8979-2019&partnerID=40&md5=c4492dd4584803db638987fdcef71156","During the boreal summer, the monsoon season that takes place in West Africa is accompanied by low stratus clouds over land that stretch from the Guinean coast several hundred kilometers inland. Numerical climate and weather models need finer description and knowledge of cloud macrophysical characteristics and of the dynamical and thermodynamical structures occupying the lowest troposphere, in order to be properly evaluated in this region. The Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) field experiment, which took place in summer 2016, addresses this knowledge gap. Low-level atmospheric dynamics and stratiform low-level cloud macrophysical properties are analyzed using in situ and remote sensing measurements continuously collected from 20 June to 30 July at Savè, Benin, roughly 180 km from the coast. The macrophysical characteristics of the stratus clouds are deduced from a ceilometer, an infrared cloud camera, and cloud radar. Onset times, evolution, dissipation times, base heights, and thickness are evaluated. The data from an ultra-high-frequency (UHF) wind profiler, a microwave radiometer, and an energy balance station are used to quantify the occurrence and characteristics of the monsoon flow, the nocturnal low-level jet, and the cold air mass inflow propagating northward from the coast of the Gulf of Guinea. The results show that these dynamical structures are very regularly observed during the entire 41 d documented period. Monsoon flow is observed every day during our study period. The so-called ""maritime inflow"" and the nocturnal low-level jet are also systematic features in this area. According to synoptic atmospheric conditions, the maritime inflow reaches Savè around 18:00-19:00 UTC on average. This timing is correlated with the strength of the monsoon flow. This time of arrival is close to the time range of the nocturnal low-level jet settlement. As a result, these phenomena are difficult to distinguish at the Savè site. The low-level jet occurs every night, except during rain events, and is associated 65 % of the time with low stratus clouds. Stratus clouds form between 22:00 and 06:00 UTC at an elevation close to the nocturnal low-level jet core height. The cloud base height, 310±30 m above ground level (a.g.l.), is rather stationary during the night and remains below the jet core height. The cloud top height, at 640±100 m a.g.l., is typically found above the jet core. The nocturnal low-level jet, low-level stratiform clouds, monsoon flow, and maritime inflow reveal significant day-to-day and intra-seasonal variability during the summer given the importance of the different monsoon phases and synoptic atmospheric conditions. Distributions of strength, depth, onset time, breakup time, etc. are quantified here. These results contribute to satisfy the main goals of DACCIWA and allow a conceptual model of the dynamical structures in the lowest troposphere over the southern part of West Africa. © 2019. This work is distributed under the Creative Commons Attribution 4.0 License."
"57210173382;56655654500;","Is Arctic Amplification Dominated by Regional Radiative Forcing and Feedbacks: Perspectives From the World-Avoided Scenario",2019,"10.1029/2019GL082320","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069793020&doi=10.1029%2f2019GL082320&partnerID=40&md5=1fb34e3e60aaf0bf94e682f0c25d3028","Arctic amplification (AA) is typically associated with Planck, lapse rate, and ice albedo feedbacks. However, the relative importance of poleward energy transport on AA remains uncertain. Here, we analyze integrations from a Chemistry Climate Model to investigate the impact of the Montreal Protocol on forcing, feedback, and transport contributions to AA. Two ensembles of future integrations are considered—one projecting decreasing ozone-depleting substance concentrations and stratospheric ozone recovery and another assuming that ozone-depleting substances are not regulated (the “World Avoided”). We find similar degrees of AA in both ensembles, despite a negative radiative forcing over the Arctic in the “World Avoided” from massive ozone loss. That negative radiative forcing is primarily balanced from positive atmospheric energy flux convergence and long-wave cloud feedbacks. Our results highlight the impact of inhomogeneous radiative forcing on regional differences in forcing and feedback strength and the importance of radiative forcing meridional structure on poleward energy transport. ©2019. American Geophysical Union. All Rights Reserved."
"56418532300;7004299063;7201488063;49261186800;","Modeling the 1783–1784 Laki Eruption in Iceland: 1. Aerosol Evolution and Global Stratospheric Circulation Impacts",2019,"10.1029/2018JD029553","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068533486&doi=10.1029%2f2018JD029553&partnerID=40&md5=54647c7441c5e5b7c652158c6128540d","The 1783–1784 CE Laki flood lava eruption began on 8 June 1783. Over the course of 8 months, the eruption released approximately 122 Tg of sulfur dioxide gas into the upper troposphere and lower stratosphere above Iceland. Previous studies that have examined the impact of the Laki eruption on sulfate aerosol and climate have either used an aerosol model coupled off-line to a general circulation model (GCM) or used a GCM with incomplete aerosol microphysics. Here, we study the impact on stratospheric aerosol evolution and stratospheric and tropospheric circulation using a fully coupled GCM with complete aerosol microphysics, the Community Earth System Model version 1, with the Whole Atmosphere Chemistry Climate Model high-top atmosphere component. Simulations indicate that the Laki aerosols had peak average effective radii of approximately 0.4 μm in Northern Hemisphere (NH) middle and high latitudes, with peak average effective radii of 0.25 μm in NH tropics and 0.2 μm in the Southern Hemisphere. We find that the Laki aerosols are transported globally and have significant impacts on the circulation in both hemispheres, strengthening the Southern Hemisphere polar vortex and shifting the tropospheric NH subtropical jet equatorward. ©2019. American Geophysical Union. All Rights Reserved."
"35336992600;57197709691;15919465200;57150132600;7402027161;57195726594;57190424816;57189498750;","Effects of Particle Nonsphericity on Dust Optical Properties in a Forecast System: Implications for Model-Observation Comparison",2019,"10.1029/2018JD030228","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068512662&doi=10.1029%2f2018JD030228&partnerID=40&md5=4224189574949b04d81c361a620bba4c","Mineral dust is a key player in the Earth system that affects the weather and climate through absorbing and scattering the radiation. Such effects strongly depend on the optical properties of the particles that are in turn affected by the particle shape. For simplicity, dust particles are usually assumed to be spherical. But this assumption can lead to large errors in modeling and remote sensing applications. This study investigates the impact of dust particle shape on its direct radiative effect in a next-generation atmospheric modeling system ICON-ART (ICOsahedral Nonhydrostatic weather and climate model with Aerosols and Reactive Trace gases) to verify if accounting for nonsphericity enhances the model-observation agreement. Two sets of numerical experiments are conducted by changing the optical shape of the particles: one assuming spherical particles and the other one assuming a mixture of 35 randomly oriented triaxial ellipsoids. The simulations are compared to MISR (Multiangle Imaging Spectroradiometer), AERONET (Aerosol Robotic Network), and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) observations (with focus on North Africa). The results show that consideration of particle nonsphericity increases the dust AOD (Aerosol Optical Depth) at 550 nm by up to 28% and leads to slight enhancement of the agreement between modeled and measured AOD. However, the model performance varies significantly when focusing on specific regions in North Africa. These differences stem from the uncertainties associated with particle size distribution and emission mechanisms in the model configuration. Regarding the attenuated backscatter, the simulated profile assuming nonsphericity differs by a factor of 2 to 5 from the experiment assuming spherical dust and is in a better agreement with the CALIPSO observations. ©2019. The Authors."
"57198337431;55534023100;25621038300;57209985163;6701797047;","Toward a Combined Surface Temperature Data Set for the Arctic From the Along-Track Scanning Radiometers",2019,"10.1029/2019JD030262","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068598662&doi=10.1029%2f2019JD030262&partnerID=40&md5=dae3f92b9ce3eb6650d31d41c544bbab","Surface temperature data sets for, or including, the Arctic have been derived from various thermal infrared sensors. However, a combined, all surface temperature data set for the Arctic has not been generated previously. Here we present the first combined land, ocean, and ice surface temperature data set for the Arctic produced from Along-Track Scanning Radiometer - 2 and the Advanced Along-Track Scanning Radiometer satellite sensors: the Along-Track Scanning Radiometer Arctic combined Surface Temperature data set. Separate products, produced independently for each sensor and containing quantified uncertainties, together cover the period August 1995 to April 2012. Product validation, utilizing a more extensive in situ database than previous studies, shows that Along-Track Scanning Radiometer Arctic combined Surface Temperature surface temperatures generally agree with in situ data and are similar to previous validation of input surface temperature retrievals. Biases range from −1.74 to 0.23 K over open ocean, sea ice, snow over land, and the Greenland ice sheet with higher variability over snow/ice. However, there are noticeable outliers in the validation results, particularly over Arctic land in boreal summer for Along-Track Scanning Radiometer - 2, which are likely due to cloud contamination resulting from a climatologically static snow field being used for that sensor. This study suggests that the Along-Track Scanning Radiometer Arctic combined Surface Temperature data set presented here is a useful tool for assessment of models in the Arctic. Further work would have clear benefits including improvements to snow cover and cloud clearing to achieve a fully consistently processed, climate quality combined surface temperature data set for the Arctic region. ©2019. The Authors."
"55913339000;57201392422;56158622800;57201394954;56780996700;","Impact of dust-polluted convective clouds over the Tibetan Plateau on downstream precipitation",2019,"10.1016/j.atmosenv.2019.04.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064322221&doi=10.1016%2fj.atmosenv.2019.04.001&partnerID=40&md5=e701b464fdfe7f0f852ce5450e3331aa","Based on satellite observations and reanalysis datasets, this study focuses on the effect of aerosols on clouds over the Tibetan Plateau (TP) and the impact of dust-polluted convective clouds on precipitation over downstream regions. A heavy dust event is detected by Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) over the northern slope of the TP on 16 July and 17 July 2016. The high aerosol optical depth (AOD) values are mainly distributed over the northern slope of the TP. Simultaneously, the CloudSat satellite observes deep convective clouds over the northern slope area of the TP, in which convective clouds and dust mix at the same height. With the AOD increasing from 16 July to its peak on 17 July, the ice particle size decreases to a minimum, and convective clouds develop at higher heights because of the prolonged cloud life. Accordingly, a larger ice water path (IWP) is induced by the development of convective clouds that move eastwardly from 16 to 17 July. In the following days, under favorable meteorological conditions, some of the developed convective clouds continuously move eastward and merge with the convective cloud clusters along the motion path, which induces significant precipitation over the Yangtze River basin on 17 July. Furthermore, driven by the northward wind, some developed convective cloud clusters move northward and induce strong precipitation over North China on 19 July. The indirect effect of dust aerosols over the TP could enhance the plateau's cloud development and potentially contribute to downstream precipitation, which is a meaningful factor for weather forecasting. © 2019"
"55747083200;23019919200;57203737916;57208484367;10938919500;","Predicting climate change impacts on the threatened Quercus arbutifolia in montane cloud forests in southern China and Vietnam: Conservation implications",2019,"10.1016/j.foreco.2019.04.028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064905666&doi=10.1016%2fj.foreco.2019.04.028&partnerID=40&md5=89ae908c703502c7c1cd93567c5cb9ce","Trees of montane cloud forests (MCFs) often have small and isolated populations and face numerous threats. Due to limited conservation resources, management decisions are often based on scarce biological information. This study investigated the current status of populations of the critically endangered oak species Quercus arbutifolia in southern China, including its distribution, threats, population structure, and area of occupancy (AOO). Additionally, by using ensembles of small models (ESMs), the present and future (2050) distributions of climatically suitable habitats were predicted throughout south China and Vietnam. The present distribution of Q. arbutifolia is extremely fragmented, with only eight confirmed populations and a very small number of individuals (ca. 1200 in total). The results presented here show that Q. arbutifolia populations suffer from habitat destruction and fragmentation, small population size, unbalanced population structure, and pressure from strong competitor species, even though all known occurrences of Q. arbutifolia are in already established nature reserves. Based on the utilized models, the current potential distribution is limited to MCFs, and 17 new areas were predicted to have complete habitats suitability for Q. arbutifolia. However, only a small area in Fujian province will remain suitable for Q. arbutifolia in the future. The current AOO of Q. arbutifolia is very small (8.49 km2), with one-third of all populations predicted to be extinct by 2050, even under the minimum emission assumption. Finally, various actions and conservation measures, such as search for new unknown populations as well as ex situ and in situ conservation, are introduced and discussed in this paper. © 2019 Elsevier B.V."
"52364270800;55334607000;","Climatological evaluation in a Central Anatolian city and indirect effects of climatological variation on air quality",2019,"10.1007/s11869-019-00703-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065709706&doi=10.1007%2fs11869-019-00703-x&partnerID=40&md5=026358ce51da55ab93cbc5f0a6ab9a73","Climate is defined as the statistics of weather over a long period of time. Climate has a dynamic structure, and climate change is caused either by natural or anthropogenic effects. Meteorological parameters are routinely recorded by national weather stations. In this study, climate variability was analyzed in a mid-populated city in the middle of the Anatolian Peninsula. Humidity, temperature, precipitation, open surface evaporation, and solar radiation records over 57-year period from 1960 to 2016 were considered. The increase in temperature and solar radiation was obvious. The increase rates were 0.05 °C and 0.62 W/m2 for temperature and solar radiation, respectively. Relative humidity showed a declining trend from 64 to 53%. This study also aimed to evaluate the climate change of planetary boundary layer development, which influences air quality level. AERMET, which is the AERMOD meteorological preprocessor was exploited in order to simulate the planetary boundary layer height, and twice daily upper air soundings, wind speed, wind direction, ambient temperature, and cloud cover have been used as minimum required parameters. The complete meteorological data available were between 2006 and 2016; for that reason, the boundary layer was calculated for 11 years. The determined average boundary layer height was 1018 m in 2006 and was reduced to 889 m in 2016. © 2019, Springer Nature B.V."
"56083968500;7102010848;8438057200;7006495018;56151545200;55687369200;57200567151;57200961120;57188999514;56329860500;55625202166;56927705400;55713234700;56927902400;56815958800;57216424628;57204366938;57193162662;7003284853;8722362600;","Direct measurement of new particle formation based on tethered airship around the top of the planetary boundary layer in eastern China",2019,"10.1016/j.atmosenv.2019.04.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064389936&doi=10.1016%2fj.atmosenv.2019.04.024&partnerID=40&md5=396b6e3ab310e6849116b6a4b8fa27b1","New particle formation (NPF) is one main source of atmospheric aerosols and plays an important role in global climate by contributing up to two thirds of the atmospheric cloud condensation nuclei. Numerous studies on characteristics and mechanisms of near-surface NPF have been conducted in last decades. However, the characteristics of NPF around the top of the planetary boundary layer (PBL) remains unclear due to the limitations of vertical measurements. In this study, a tethered airship onboard with advanced particle instruments was deployed for directly measurement of the NPF exactly above and under the top of the PBL in the Yangtze River Delta (YRD) of eastern China in December 2017. Coupled with the real time ground Lidar observation, we successfully conducted measurement of aerosol size distribution, chemical components of aerosol and gas pollutants with 100 m above/under the top of the PBL. Despite not being observed within the PBL during the flight and at three ground sites in YRD, NPF event with the growth rate of 3.8 nm/h was detected above the PBL. High oxidizing capacity, enough condensable vapors and low condensation sink above the PBL favor the onset of NPF. Model simulation and the aerosol chemical composition result indicate the important role of gaseous sulfuric acid in NPF and its subsequent growth in the upper atmosphere. Our study highlights the potential mechanism of NPF above the PBL and the need of direct vertical measurements to better understand NPF in the atmosphere and its climate effect. © 2019 Elsevier Ltd"
"57208276276;56491776600;57194626142;57208310891;57208273678;35236807700;57103196700;8581523500;56411079900;","Size distribution and chemical composition of primary particles emitted during open biomass burning processes: Impacts on cloud condensation nuclei activation",2019,"10.1016/j.scitotenv.2019.03.419","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064313304&doi=10.1016%2fj.scitotenv.2019.03.419&partnerID=40&md5=6cf5b7c9bc63cc3e627c64b0fd8a2d79","As a major source of fine particles, open biomass burning can affect climate and the hydrological cycle via the formation of cloud condensation nuclei (CCN) and their deposition. This study investigated the effect of aerosol size and chemical composition (water-soluble compounds, elemental carbon, and organic carbon) on CCN activation during the complete combustion of six commonly used crop (rice, wheat, corn, soybean, and cotton) and leaf residues in a simulation chamber developed for this study. Geometric mean diameters (GMD) of emitted primary particles ranged from 68 to 130 nm and water-soluble compound (WSC) content ranged from 33 to 50%. Although GMDs and WSCs possessed similar temporal tendencies during the combustion process, their average values were dependent on the type of biomass. Number concentration ratios of CCN and particle (CCN/CN) ranged from 1.4–2.1% and 5.8–8.3% at supersaturations of 0.2% and 1.0%, respectively. The CCN/CN value increased during the combustion process when the GMD and WSC content increased. Correlation coefficients for GMD and CCN activation ranged from 0.62 to 0.93, while correlations for WSC and CCN activation ranged from 0.33 to 0.95. Soybean biomass had the highest correlations for both GMD and WSC with CCN activation at various supersaturations. These results suggest that the size and chemical composition of biomass aerosols are important in CCN formation, while the aerosol size has a higher impact. © 2019 Elsevier B.V."
"10241807900;57203915830;57192160901;57208408764;57208390547;37099569600;36438463500;7407051300;57208410186;57214563572;7004832388;","The mixing state of mineral dusts with typical anthropogenic pollutants: A mechanism study",2019,"10.1016/j.atmosenv.2019.04.035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064682084&doi=10.1016%2fj.atmosenv.2019.04.035&partnerID=40&md5=994d75d952900567cdad3df480bb6d49","The particle mixing state is a key feature in determining their role in the earth system, exerting a substantial impact on radiative forcing and climate. However, the mechanism of particle mixing reactions is unclear, especially for the mixing of mineral dusts with anthropogenic pollutants (APs). In this study, the mixing reaction mechanisms of typical APs (acrolein, SOx, and NOx) with mineral dust (SiO2) were investigated by using theoretical approach. The mixing ability of SiO2 with inorganic compounds mainly depends on the strength of the interaction of the center atom of inorganic compounds and the surface of SiO2, while SiO2 mixed with acrolein (ARL) proceeds via only hydrogen bonding (HB). The nucleation ability of SiO2 is enhanced significantly from simultaneous existence of ARL and SOx/NOx. SiO2 exhibits a high reactivity with SO3 and acrolein (ARL), proceeding an irreversible process. The mixing reactions of SO2/NOx and SiO2 are reversible, but the binding is enhanced by ARL, which contributes to the dust aerosol nucleation process by binding to SO2/NOx and SiO2. The charge density difference and natural bond orbital analysis show that organic compound acts as both hydrogen bonding (HB) donors and acceptors, while inorganic compound is only HB acceptor. Our results reveal that the mixing state of mineral dust with anthropogenic pollutant is largely facilitated in area with rapid industrialization and urbanization, which could further influence climate and radiative forcing. © 2019 Elsevier Ltd"
"57207471175;10341128500;12807825500;57213340327;13805286500;","Performance evaluation of WRF for extreme flood forecasts in a coastal urban environment",2019,"10.1016/j.atmosres.2019.03.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062526196&doi=10.1016%2fj.atmosres.2019.03.005&partnerID=40&md5=fe75bba5d5f8543b8edd8fec25d576e8","Increasing incidences of flash floods highlight the need for a reliable flood forecasting system to minimize the losses of lives and property. The most formidable challenge of flood forecasting is the availability of high resolution and accurate precipitation forecast despite having a sophisticated 3-ways flood hydrodynamic model. Global rainfall forecasting products are of coarse resolution, which makes them less reliable for urban flood forecasting. Therefore, high-resolution regional weather forecasting models such as the Weather Research and Forecasting (WRF) model are used to generate fine-scale rainfall estimates. Precipitation forecasting from the WRF model is highly dependent on model configuration, especially cumulus (CU) parameterization and microphysics (MP) schemes. In the present study, three physics schemes that include two urban, four CU and three MP schemes of WRF model are investigated for extreme precipitation estimates. The six events comprised of two of the highest rainfall events of the years 2012, 2013 and 2014 have been selected for investigation over Mumbai, India. The events are simulated using initial and boundary conditions from the ERA-Interim Reanalysis dataset. The simulated rainfall events are evaluated against the observations from 28 automatic weather stations over Mumbai. The analysis suggests that building environment parameterization (BEP) scheme influences the spatial pattern of the rainfall along with the reduction in rainfall bias. Further, CU schemes affect the magnitude of the rainfall while MP schemes have a lesser impact than the former. WRF simulations with BEP urban scheme, Grell-Devenyi 3D CU, and Lin MP scheme performs best (out of selected combinations). Besides, the best performing scheme has been tested with initial and boundary conditions from the global forecasting system (GFS) for the same events; the results have shown improved rainfall estimates than the GFS forecasts. © 2019 Elsevier B.V."
"56531065100;57208275387;57204914178;57203579680;6603653680;","Spatiotemporal patterns and characteristics of remotely sensed region heat islands during the rapid urbanization (1995–2015) of Southern China",2019,"10.1016/j.scitotenv.2019.04.088","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064328893&doi=10.1016%2fj.scitotenv.2019.04.088&partnerID=40&md5=19f07576b52e5285fc82934e7a5483a1","Urban agglomeration has become the most salient feature of global urbanization in recent decades, while spatiotemporal patterns and evolution remain poorly understood in urban agglomerations, which limit the decision-makers to make more informed decisions to improve the regional environment. Here we selected one of the most rapidly urbanized regions in the world – Pearl River Delta Metropolitan Region (PRDR), located in southern China, as the case. Landsat images spanning from 1995 to 2015 were used to retrieve land surface temperature (LST). Four types of regional heat island (RHI) degree were defined for further analysis. Then multi-scale spatiotemporal patterns and characteristics of RHI were identified with the help of cloud-based computing, spatial and landscape analysis. We found that (1) traditional urban heat island (UHI) appears as an RHI on an urban agglomeration scale. In PRDR, we found RHI expended with increasing connectivity, especially in the estuary areas where isolated UHI gradually merged during the rapid urbanization. (2) The contribution of main cities in PRDR to RHI and the evolutionary trends and pattern, which is changed from a west-east to a southwest-northeast gradient, have been revealed. (3) Considering the scale effect and different RHI categories, we revealed that during the urbanization, the aggregation of the RHI is significant on a larger-scale, and the area of 4 °C ≤ Relative LST ≤ 8 °C is the stable and high-risk area, which provide scientific bases for the governance of the thermal environment on the regional scale. (4) The study also indicates the cooling effect of forests and water is better than that of grassland, while the cooling effect of grassland is uncertain. The methods and results of this study not only have implications on environmental planning and management in the PRDR but also provide useful insights into the thermal environment research and practice in other urban agglomerations. © 2019 Elsevier B.V."
"13405561000;6603412788;8918407000;56823691200;10739772300;7402345338;13406148400;","Significant improvement of cloud representation in the global climate model MRI-ESM2",2019,"10.5194/gmd-12-2875-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068933428&doi=10.5194%2fgmd-12-2875-2019&partnerID=40&md5=9662eb7aecb8bff48000e8fc4ceb5898","The development of the climate model MRI-ESM2 (Meteorological Research Institute Earth System Model version 2), which is planned for use in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) simulations, involved significant improvements to the representation of clouds from the previous version MRI-CGCM3 (Meteorological Research Institute Coupled Global Climate Model version 3), which was used in the CMIP5 simulations. In particular, the serious lack of reflection of solar radiation over the Southern Ocean in MRI-CGCM3 was drastically improved in MRI-ESM2. The score of the spatial pattern of radiative fluxes at the top of the atmosphere for MRI-ESM2 is better than for any CMIP5 model. In this paper, we set out comprehensively the various modifications related to clouds that contribute to the improved cloud representation and the main impacts on the climate of each modification. The modifications cover various schemes and processes including the cloud scheme, turbulence scheme, cloud microphysics processes, interaction between cloud and convection schemes, resolution issues, cloud radiation processes, interaction with the aerosol model, and numerics. In addition, the new stratocumulus parameterization, which contributes considerably to increased low-cloud cover and reduced radiation bias over the Southern Ocean, and the improved cloud ice fall scheme, which alleviates the time-step dependency of cloud ice content, are described in detail. © Author(s) 2019."
"49661238200;8554472500;57209852763;14626695500;7005242447;","Performance of bias-correction schemes for CMORPH rainfall estimates in the Zambezi River basin",2019,"10.5194/hess-23-2915-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068912940&doi=10.5194%2fhess-23-2915-2019&partnerID=40&md5=87b331e9c8547309741173d2699a6f54","Satellite rainfall estimates (SREs) are prone to bias as they are indirect derivatives of the visible, infrared, and/or microwave cloud properties, and hence SREs need correction. We evaluate the influence of elevation and distance from large-scale open water bodies on bias for Climate Prediction Center-MORPHing (CMORPH) rainfall estimates in the Zambezi basin. The effectiveness of five linear/non-linear and time space-variant/-invariant bias-correction schemes was evaluated for daily rainfall estimates and climatic seasonality. The schemes used are spatio-temporal bias (STB), elevation zone bias (EZ), power transform (PT), distribution transformation (DT), and quantile mapping based on an empirical distribution (QME). We used daily time series (1998 2013) from 60 gauge stations and CMORPH SREs for the Zambezi basin. To evaluate the effectiveness of the bias-correction schemes spatial and temporal crossvalidation was applied based on eight stations and on the 1998 1999 CMORPH time series, respectively. For correction, STB and EZ schemes proved to be more effective in removing bias. STB improved the correlation coefficient and Nash Sutcliffe efficiency by 50% and 53 %, respectively, and reduced the root mean squared difference and relative bias by 25% and 33 %, respectively. Paired t tests showed that there is no significant difference (p>0:05) in the daily means of CMORPH against gauge rainfall after bias correction. ANOVA post hoc tests revealed that the STB and EZ bias-correction schemes are preferable. Bias is highest for very light rainfall (>2:5mmd1), for which most effective bias reduction is shown, in particular for the wet season. Similar findings are shown through quantile quantile (q q) plots. The spatial cross-validation approach revealed that most bias-correction schemes removed bias by <28 %. The temporal cross-validation approach showed effectiveness of the bias-correction schemes. Taylor diagrams show that station elevation has an influence on CMORPH performance. Effects of distance <10 km from large-scale open water bodies are minimal, whereas effects at shorter distances are indicated but are not conclusive for a lack of rain gauges. Findings of this study show the importance of applying bias correction to SREs. © 2019 by ASME."
"57209982792;57210158750;56593937600;55731303900;57203523035;7402530272;","Nucleation-mode particle pool and large increases in Ncn and Nccn observed over the northwestern Pacific Ocean in the spring of 2014",2019,"10.5194/acp-19-8845-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069159590&doi=10.5194%2facp-19-8845-2019&partnerID=40&md5=94a53a3930345f19e21f1e32b2684b0c","Determination of the updated concentrations of atmospheric particles (Ncn) and the concentrations of cloud condensation nuclei (Nccn) over the northwestern Pacific Ocean (NWPO) are important to accurately evaluate the influence of aerosol outflow from the Asian continent on the climate by considering the rapid changes in emissions of air pollutants therein. However, field observations in the last two decades are scarce. We conducted a cruise campaign over the NWPO to simultaneously measure Ncn, Nccn and the size distribution of aerosol particles from day of year (DOY) 81 to DOY 108 of 2014. The mean values of Nccn at supersaturation (SS) of levels 0.2% and 0.4% were 0:68±0:387times;103 and 1:1±0:67×103 cm-3, respectively, with an average of 2:8± 1:0×103 cm-3 for Ncn during the cruise over the NWPO. All are approximately 1 order of magnitude larger than spring observations made during the preceding two decades in the remote marine atmosphere. The larger values, against the marine natural background reported in the literature, imply an overwhelming contribution from continental inputs. The calculated activity ratios (ARs) of the cloud condensation nuclei (CCN) were 0:30 ± 0:11 and 0:46 ± 0:19 at SS levels of 0.2 % and 0.4 %, respectively, which are almost the same as those of upwind semi-urban sites. High Nccn and CCN activities were observed from DOY 98 to DOY 102, when the oceanic zone received even stronger continental input. Excluding biomass burning (BB) and dust aerosols, good correlation between Nccn at 0.4 % SS and the number concentrations of > 60 nm particles (N>60 nm) was obtained during the entire cruise period, with a slope of 0.98 and R2 = 0:94, and the corresponding effective hygroscopicity parameter (k) was estimated to be 0.40. A bimodal size distribution pattern of the particle number concentration was generally observed during the entire campaign when the N>90 nm varied largely. However, the N<30 nm, accounting for approximately one-third of the total number concentration, varied narrowly, and two NPF events associated with vertical transport were observed. This implies that a pool of nucleation-mode atmospheric particles is aloft. BB and dust events were observed over the NWPO, but their aerosol contributions to Ncn and Nccn were minor (i.e., 10 % or less) on a monthly timescale. © Author(s) 2019."
"12769875100;55747560500;55268661300;57209911739;","Arctic cloud annual cycle biases in climate models",2019,"10.5194/acp-19-8759-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069055042&doi=10.5194%2facp-19-8759-2019&partnerID=40&md5=ccec384ed0fe1c3babaf16e4fdce4a5b","Arctic clouds exhibit a robust annual cycle with maximum cloudiness in fall and minimum cloudiness in winter. These variations affect energy flows in the Arctic with a large influence on the surface radiative fluxes. Contemporary climate models struggle to reproduce the observed Arctic cloud amount annual cycle and significantly disagree with each other. The goal of this analysis is to quantify the cloud-influencing factors that contribute to winter-summer cloud amount differences, as these seasons are primarily responsible for the model discrepancies with observations. We find that differences in the total cloud amount annual cycle are primarily caused by differences in low, rather than high, clouds; the largest differences occur between the surface and 950 hPa. Grouping models based on their seasonal cycles of cloud amount and stratifying cloud amount by cloud-influencing factors, we find that model groups disagree most under strong lower tropospheric stability, weak to moderate mid-tropospheric subsidence, and cold lower tropospheric air temperatures. Intergroup differences in low cloud amount are found to be a function of lower tropospheric thermodynamic characteristics. Further, we find that models with a larger low cloud amount in winter have a larger ice condensate fraction, whereas models with a larger low cloud amount in summer have a smaller ice condensate fraction. Stratifying model output by the specifics of the cloud microphysical scheme reveals that models treating cloud ice and liquid condensate as separate prognostic variables simulate a larger ice condensate fraction than those that treat total cloud condensate as a prognostic variable and use a temperature-dependent phase partitioning. Thus, the cloud microphysical parameterization is the primary cause of inter-model differences in the Arctic cloud annual cycle, providing further evidence of the important role that cloud ice microphysical processes play in the evolution and modeling of the Arctic climate system. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License."
"6602740671;7003489918;6701378450;22978151200;17345303300;7004469744;6507533363;56540693200;56571063800;21742333400;12139043600;56682032300;57203053317;9275665400;23051160600;49662076300;23095483400;13405658600;36106370400;57208121852;6507308842;55885662200;55688930000;36462180600;36969949500;55720018700;56377286600;16425152300;55984424900;57189748029;15065491600;55717074000;6603711967;23485829700;36469200100;12804476900;21744073500;57201942906;38762392200;","Evaluation of global simulations of aerosol particle and cloud condensation nuclei number, with implications for cloud droplet formation",2019,"10.5194/acp-19-8591-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068570626&doi=10.5194%2facp-19-8591-2019&partnerID=40&md5=f7bc6775c7c03a158c0056f7de33aaa6","A total of 16 global chemistry transport models and general circulation models have participated in this study; 14 models have been evaluated with regard to their ability to reproduce the near-surface observed number concentration of aerosol particles and cloud condensation nuclei (CCN), as well as derived cloud droplet number concentration (CDNC). Model results for the period 2011-2015 are compared with aerosol measurements (aerosol particle number, CCN and aerosol particle composition in the submicron fraction) from nine surface stations located in Europe and Japan. The evaluation focuses on the ability of models to simulate the average across time state in diverse environments and on the seasonal and short-term variability in the aerosol properties. There is no single model that systematically performs best across all environments represented by the observations. Models tend to underestimate the observed aerosol particle and CCN number concentrations, with average normalized mean bias (NMB) of all models and for all stations, where data are available, of -24% and -35% for particles with dry diameters >50 and >120nm, as well as -36% and -34% for CCN at supersaturations of 0.2% and 1.0%, respectively. However, they seem to behave differently for particles activating at very low supersaturations (<0.1%) than at higher ones. A total of 15 models have been used to produce ensemble annual median distributions of relevant parameters. The model diversity (defined as the ratio of standard deviation to mean) is up to about 3 for simulated N3 (number concentration of particles with dry diameters larger than 3nm) and up to about 1 for simulated CCN in the extra-polar regions. A global mean reduction of a factor of about 2 is found in the model diversity for CCN at a supersaturation of 0.2% (CCN0.2) compared to that for N3, maximizing over regions where new particle formation is important. An additional model has been used to investigate potential causes of model diversity in CCN and bias compared to the observations by performing a perturbed parameter ensemble (PPE) accounting for uncertainties in 26 aerosol-related model input parameters. This PPE suggests that biogenic secondary organic aerosol formation and the hygroscopic properties of the organic material are likely to be the major sources of CCN uncertainty in summer, with dry deposition and cloud processing being dominant in winter. Models capture the relative amplitude of the seasonal variability of the aerosol particle number concentration for all studied particle sizes with available observations (dry diameters larger than 50, 80 and 120nm). The short-term persistence time (on the order of a few days) of CCN concentrations, which is a measure of aerosol dynamic behavior in the models, is underestimated on average by the models by 40% during winter and 20% in summer. In contrast to the large spread in simulated aerosol particle and CCN number concentrations, the CDNC derived from simulated CCN spectra is less diverse and in better agreement with CDNC estimates consistently derived from the observations (average NMB -13% and -22% for updraft velocities 0.3 and 0.6ms-1, respectively). In addition, simulated CDNC is in slightly better agreement with observationally derived values at lower than at higher updraft velocities (index of agreement 0.64 vs. 0.65). The reduced spread of CDNC compared to that of CCN is attributed to the sublinear response of CDNC to aerosol particle number variations and the negative correlation between the sensitivities of CDNC to aerosol particle number concentration (Nd=Na) and to updraft velocity (Nd=w). Overall, we find that while CCN is controlled by both aerosol particle number and composition, CDNC is sensitive to CCN at low and moderate CCN concentrations and to the updraft velocity when CCN levels are high. Discrepancies are found in sensitivities Nd=Na and Nd=w; models may be predisposed to be too ""aerosol sensitive"" or ""aerosol insensitive"" in aerosol-cloud-climate interaction studies, even if they may capture average droplet numbers well. This is a subtle but profound finding that only the sensitivities can clearly reveal and may explain intermodel biases on the aerosol indirect effect. © Author(s) 2019."
"55783064400;57193496623;7006377579;7201787800;22834248200;7103197731;7006235542;57205787051;57209736590;7004944088;14058796400;24465126800;55683878900;8657166100;57195325985;56495287900;55226243300;35551238800;8760535800;56494338400;26659013400;7201572145;8412336900;6602999057;7006837187;","Aerosol influences on low-level clouds in the West African monsoon",2019,"10.5194/acp-19-8503-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060993873&doi=10.5194%2facp-19-8503-2019&partnerID=40&md5=26f836c1dded7c865e4a8ab960fd290d","Low-level clouds (LLCs) cover a wide area of southern West Africa (SWA) during the summer monsoon months and have an important cooling effect on the regional climate. Previous studies of these clouds have focused on modelling and remote sensing via satellite. We present the first comprehensive set of in situ measurements of cloud microphysics from the region, taken during June-July 2016, as part of the DACCIWA (Dynamics-aerosol-chemistry-cloud interactions in West Africa) campaign. This novel dataset allows us to assess spatial, diurnal, and day-to-day variation in the properties of these clouds over the region. LLCs developed overnight and mean cloud cover peaked a few hundred kilometres inland around 10:00 local solar time (LST), before clouds began to dissipate and convection intensified in the afternoon. Regional variation in LLC cover was largely orographic, and no lasting impacts in cloud cover related to pollution plumes were observed downwind of major population centres. The boundary layer cloud drop number concentration (CDNC) was locally variable inland, ranging from 200 to 840 cm-3 (10th and 90th percentiles at standard temperature and pressure), but showed no systematic regional variations. Enhancements were seen in pollution plumes from the coastal cities but were not statistically significant across the region. A significant fraction of accumulation mode aerosols, and therefore cloud condensation nuclei, were from ubiquitous biomass burning smoke transported from the Southern Hemisphere. To assess the relative importance of local and transported aerosol on the cloud field, we isolated the local contribution to the aerosol population by comparing inland and offshore size and composition measurements. A parcel model sensi- tivity analysis showed that doubling or halving local emissions only changed the calculated cloud drop number concentration by 13 %-22 %, as the high background meant local emissions were a small fraction of total aerosol. As the population of SWA grows, local emissions are expected to rise. Biomass burning smoke transported from the Southern Hemisphere is likely to dampen any effect of these increased local emissions on cloud-aerosol interactions. An integrative analysis between local pollution and Central African biomass burning emissions must be considered when predicting anthropogenic impacts on the regional cloud field during the West African summer monsoon. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License."
"37013451200;56739408000;16319107300;","Spatiotemporal characteristics of ultraviolet solar radiation in China",2019,"10.1080/16742834.2019.1617627","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067801602&doi=10.1080%2f16742834.2019.1617627&partnerID=40&md5=86759070cffe9c522b0d43a20bfe43de","UV radiation plays an important role in climate change and photochemical reactions, and in Ecosystem Research. In this study, the authors presented study results of China’s National Basic Research Program Study on the climatic characteristics and reconstruction method of UV radiation in China. The spatiotemporal variation of UV radiation in China has been discussed, and then an efficient modeling method has been established to obtain history UV radiation data to analyse the variation trends of UV radiation in China. Finally, the influence of aerosol, cloud, ozone, and water vapor on UV radiation has been discussed. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"57162224700;7408519295;7402061743;57206621863;56927197200;","Unprecedented East Asian warming in spring 2018 linked to the North Atlantic tripole SST mode",2019,"10.1080/16742834.2019.1605807","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067817756&doi=10.1080%2f16742834.2019.1605807&partnerID=40&md5=b54bf7d8d9edc6e6fc12c4e4817993ce","An unusually warm East Asia in spring 2018, when exceptionally high surface air temperatures were recorded in large areas of Asia, such as northern China, southern China, and Japan, was investigated based on the ERA-Interim reanalysis. The East Asian warming anomalies were primarily attributed to a tripole mode of North Atlantic SST anomalies, which could have triggered anomalous Rossby wave trains over the North Atlantic and Eurasia through modulating the North Atlantic baroclinic instability. Atlantic-forced Rossby waves tend to propagate eastward and induce anomalously high pressure and anticyclonic activity over East Asia, leading to a northward displacement of the Pacific subtropical high. As a result, descending motion, reduced precipitation, and increased surface solar radiation due to less cloud cover appear over East Asia, accompanied by remarkably warm advection from the ocean to southern China, northern China, and Japan. The transportation of anomalously warm advection and the feedbacks between soil moisture and surface temperature were both favorable for the record-breaking warmth in East Asia during spring 2018. The seasonal ‘memory’ of the North Atlantic tripole SST mode from the previous winter to the following spring may provide useful implications for the seasonal prediction of East Asian weather and climate. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"7007146465;6701650121;6603516536;7006269588;47161355500;6701498473;57208305685;55613234906;55961353300;9248919400;57214493184;6602478960;57194168161;57212075803;57213799167;24450883600;10142675100;23976149400;57211331113;7501381728;7406258560;57209674986;24280225800;57191373498;7102020573;56679340600;57211342728;23866122100;6603742681;57211335426;57211334892;7202489497;10639401400;","The Atmospheric Imaging Mission for Northern Regions: AIM-North",2019,"10.1080/07038992.2019.1643707","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068501067&doi=10.1080%2f07038992.2019.1643707&partnerID=40&md5=ed1e3c7fac613bfe5d674d5d2143ca4f","AIM-North is a proposed satellite mission that would provide observations of unprecedented frequency and density for monitoring northern greenhouse gases (GHGs), air quality (AQ) and vegetation. AIM-North would consist of two satellites in a highly elliptical orbit formation, observing over land from ∼40°N to 80°N multiple times per day. Each satellite would carry a near-infrared to shortwave infrared imaging spectrometer for CO2, CH4, and CO, and an ultraviolet-visible imaging spectrometer for air quality. Both instruments would measure solar-induced fluorescence from vegetation. A cloud imager would make near-real-time observations, which could inform the pointing of the other instruments to focus only on the clearest regions. Multiple geostationary (GEO) AQ and GHG satellites are planned for the 2020s, but they will lack coverage of northern regions like the Arctic. AIM-North would address this gap with quasi-geostationary observations of the North and overlap with GEO coverage to facilitate intercomparison and fusion of these datasets. The resulting data would improve our ability to forecast northern air quality and quantify fluxes of GHG and AQ species from forests, permafrost, biomass burning and anthropogenic activity, furthering our scientific understanding of these processes and supporting environmental policy. © 2019, © 2019 Copyright of the Crown in Canada. Climate Research Division."
"7402323784;","Clinal polymorphism variation in the Booted Eagle Hieraaetus pennatus: the influence of climate during the breeding season",2019,"10.1080/00063657.2019.1657064","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073808524&doi=10.1080%2f00063657.2019.1657064&partnerID=40&md5=06b29878de7febc90b1e1cce6d4a4dd5","Capsule: The existence of clinal variation in the colour polymorphism of the Booted Eagle Hieraaetus pennatus in its breeding area in the Palaearctic is probably caused by the influence of precipitation and the detectability of the two morphs in different light conditions. Aims: To test whether Booted Eagles shows clinal variation in colour polymorphism along its breeding range in the Palaearctic and to test if there was selective or/and environmental pressure in the polymorphism throughout its breeding range in the Palaearctic and South Africa. Methods: Published data were obtained on the proportion of colour morphs of seven study populations within the Palaearctic and South Africa, as well as those of 11 populations on the Iberian Peninsula, and the variation was examined in relation to longitude, latitude, and environmental and meteorological variables. Results: There was a strong relationship between the proportion of the dark morph and longitude from west to east. In the Palaearctic and South Africa, there was a strong positive relationship between the proportion of the dark morph and the amount of rainfall during the period of chick growth. Conclusion: There is clinal variation in colour polymorphism in the Booted Eagle. The variation is probably maintained by disruptive selection due to climatic factors such as rain and cloud cover, which influence the detectability of the different colour morphs to their prey. © 2019, © 2019 British Trust for Ornithology."
"57213521610;57198674858;57205488783;57192588685;57196713099;57201698175;8953662800;","Elucidating cloud vertical structures based on three-year Ka-band cloud radar observations from Beijing, China",2019,"10.1016/j.atmosres.2019.02.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062146036&doi=10.1016%2fj.atmosres.2019.02.007&partnerID=40&md5=6496ec45f7f0afeddef2cdf433bf1b5d","Elucidating the vertical structures of clouds is key to reducing the uncertainty in cloud-induced climate forcing; however, we do not yet know explicitly about the cloud structures that form over Beijing, China, and how they vary. In this paper, we document vertically resolved cloud structures and their climatological variation based on three-year (1 January 2015 to 31 December 2017) ground-based Ka-band (35 GHz) millimeter-wave cloud radar (MMCR) measurements. Cloud top height (CTH) and radar reflectivity are higher in summer and autumn than in spring and winter. We verified the MMCR measurements of the CTH and cloud base height (CBH) independently based on observations from the Himawari-8 and CL51 ceilometer at the same station, respectively. The CTH decreased as the thickness of the cloud layer increased. This may have been due to the mechanism used to determine the CTH, which was based on data from the satellite infrared channel. There were two peaks in the CBH distribution, located at 0–1 km and 5–6 km, whereas the frequency of the CTH peaked at an altitude of 9–10 km, between 1200 and 1800 LST. Precipitating clouds tended to be located at lower altitudes and exhibited stronger radar reflectivities than non-precipitating clouds. The cloud frequency tended to peak in autumn and reached a minimum in winter. In terms of the seasonality of clouds at various levels, middle- and high-level clouds were dominant over Beijing, with high and low (precipitating) clouds concentrated between May and October. Mid-altitude clouds occurred more frequently in winter and spring. CTH peaked in summer due to the strong solar radiation received by the surface. In contrast, minimum CBH occurred in winter. The cloud heights were higher and radar reflectivities larger than reported in previous studies. These results are correlated with urban warming effects. Understanding the properties of clouds will not only be of benefit to researchers carrying out cloud forcing studies, but will also provide key validation data for climate model simulations. © 2019 Elsevier B.V."
"7006422317;","Weather forecasting in Iindia: Recent developments",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073438072&partnerID=40&md5=939fc676c238b9ab4f563a8b41ad83f1","This review article aims to highlight the recent research accomplishments on weather and climate sciences of India mostly during last decade in a concise manner. These research works were mainly carried out at educational institutes, research centers and operational agencies within India. The research achievements are organized into six sections namely monsoon, synoptic scale systems, tropical cyclones, cloud aerosol and air quality, severe weather systems, data sets and observation campaign. The discussions are restricted to highlighting few key results, keeping in view its long term implications on the weather and climate services in India with focus on improving the skills of dynamical forecasting systems for wide range of socioeconomic applications. Results discussed here are comprises of different spatiotemporal scales ranging from nowcasting to climate scale. Finally, the research accomplished milestones are summarized with emphasis on challenges ahead. In order to maintain the momentum of achieving higher milestones and holistic development of weather and climate science research in India, few points with achievable roadmap are suggested. Sustained effort in this direction, will not only provide valuable inputs to improve our research and operational forecasting capabilities but also enable us to effectively address continuously evolving outstanding grand challenges in weather and climate services of India in the 21st century. © 2019, India Meteorological Department. All rights reserved."
"57194682576;22635999400;57126848900;7003444634;57209647985;56210720700;18134565600;","Polarimetric retrievals of cloud droplet number concentrations",2019,"10.1016/j.rse.2019.04.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058147019&doi=10.1016%2fj.rse.2019.04.008&partnerID=40&md5=5db55345566c99eb6ffc65fc1e37aacf","Cloud droplet number concentration (Nd)is an important parameter of liquid clouds and is crucial to understanding aerosol-cloud interactions. It couples boundary layer aerosol composition, size and concentration with cloud reflectivity. It affects cloud evolution, precipitation, radiative forcing, global climate and, through observation, can be used to partially monitor the first indirect effect. With its unique combination of multi-wavelength, multi-angle, total and polarized reflectance measurements, the Research Scanning Polarimeter (RSP)retrieves Nd with relatively few assumptions. The approach involves measuring cloud optical thickness, mean droplet extinction cross-section and cloud physical thickness. Polarimetric observations are capable of measuring the effective variance, or width, of the droplet size distribution. Estimating cloud geometrical thickness is also an important component of the polarimetric Nd retrieval, which is accomplished using polarimetric measurements in a water vapor absorption band to retrieve the amount of in-cloud water vapor and relating this to physical thickness. We highlight the unique abilities and quantify uncertainties of the polarimetric approach. We validate the approach using observational data from the North Atlantic and Marine Ecosystems Study (NAAMES). NAAMES targets specific phases in the seasonal phytoplankton lifecycle and ocean-atmosphere linkages. This study provides an excellent opportunity for the RSP to evaluate its approach of sensing Nd over a range of concentrations and cloud types with in situ measurements from a Cloud Droplet Probe (CDP). The RSP and CDP, along with an array of other instruments, are flown on the NASA C-130 aircraft, which flies in situ and remote sensing legs in sequence. Cloud base heights retrieved by the RSP compare well with those derived in situ (R = 0.83)and by a ceilometer aboard the R.V. Atlantis (R = 0.79). Comparing geometric mean values from 12 science flights throughout the NAAMES-1 and NAAMES-2 campaigns, we find a strong correlation between Nd retrieved by the RSP and CDP (R = 0.96). A linear least squares fit has a slope of 0.92 and an intercept of 0.3 cm−3. Uncertainty in this comparison can be attributed to cloud 3D effects, nonlinear liquid water profiles, multilayered clouds, measurement uncertainty, variation in spatial and temporal sampling, and assumptions used within the method. Radiometric uncertainties of the RSP measurements lead to biases on derived optical thickness and cloud physical thickness, but these biases largely cancel out when deriving Nd for most conditions and geometries. We find that a polarimetric approach to sensing Nd is viable and the RSP is capable of accurately retrieving Nd for a variety of cloud types and meteorological conditions. © 2019 Elsevier Inc."
"57199180112;57211399319;57190428630;57211388004;10738896100;8581523500;57194689160;57205751442;11340215800;57198710036;57202109092;57211392287;","Effects of shipping-originated aerosols on physical cloud properties over marine areas near east China",2019,"10.4209/aaqr.2018.11.0415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073746788&doi=10.4209%2faaqr.2018.11.0415&partnerID=40&md5=e46c8d663a32329085cb3602f989fd69","Shipping emissions have received increasing attention due to their influence on regional climate, and air quality at ports and in coastal areas around the world. In the context of climatology, the effects of shipping-originated aerosols (using the aerosol optical depth, AODship, as a proxy) on clouds in marine areas near East China were examined based on multisatellite datasets. On average, AODship is approximately 0.17, 0.20, 0.15 and 0.13 in the different seasons, contributing 23%, 30%, 36% and 25% of the total AOD, respectively. In remote sea areas, AODship is generally higher in spring and summer and lower in autumn. Statistical analysis shows that it is strongly related to the cloud parameters, such as the cloud fraction (CF), cloud optical thickness (COT) and cloud effective radius (CER) in the liquid phase. In particular, CER and AODship exhibit a positive correlation in winter but a weakly negative correlation in summer over the northern East China Sea and a positive correlation in spring and summer over the Yellow Sea. In all four seasons, COT and CF decrease as AODship increases. The correlations between AODship and the cloud properties are stronger (R > 0.3) when the aerosolcloud layers are well mixed than when they are separated, indicating that shipping-originated aerosols drawn into the cloud body can directly affect the microphysical properties of cloud droplets during cloud formation. The water vapor content and upward air motion are key thermodynamic conditions within the low atmospheric layers under the cloud bottom that play an important role in cloud formation and development. Our results provide new insight into the influence of shipping emissions on clouds in Asian marine areas. © Taiwan Association for Aerosol Research."
"57194334833;8518459900;57189501249;57191358778;55424752100;16641272900;35509463200;7005165467;","Generation and evaluation of LAI and FPAR products from Himawari-8 advanced Himawari imager (AHI) data",2019,"10.3390/rs11131517","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068509206&doi=10.3390%2frs11131517&partnerID=40&md5=9a19bfc69857e346802c1e5c3faf31a7","Leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) absorbed by vegetation are two of the essential biophysical variables used in most global models of climate, hydrology, biogeochemistry, and ecology. Most LAI/FPAR products are retrieved from non-geostationary satellite observations. Long revisit times and cloud/cloud shadow contamination lead to temporal and spatial gaps in such LAI/FPAR products. For more effective use in monitoring of vegetation phenology, climate change impacts, disaster trend etc., in a timely manner, it is critical to generate LAI/FPAR with less cloud/cloud shadow contamination and at higher temporal resolution-something that is feasible with geostationary satellite data. In this paper, we estimate the geostationary Himawari-8 Advanced Himawari Imager (AHI) LAI/FPAR fields by training artificial neural networks (ANNs) with Himawari-8 normalized difference vegetation index (NDVI) and moderate resolution imaging spectroradiometer (MODIS) LAI/FPAR products for each biome type. Daily cycles of the estimated AHI LAI/FPAR products indicate that these are stable at 10-min frequency during the day. Comprehensive evaluations were carried out for the different biome types at different spatial and temporal scales by utilizing the MODIS LAI/FPAR products and the available field measurements. These suggest that the generated Himawari-8 AHI LAI/FPAR fields were spatially and temporally consistent with the benchmark MODIS LAI/FPAR products. We also evaluated the AHI LAI/FPAR products for their potential to accurately monitor the vegetation phenology-the results show that AHI LAI/FPAR products closely match the phenological development captured by the MODIS products. © 2019 by the authors."
"57195219330;57191986422;57202755927;6603860293;7403897936;","Simulations and experimental results of cloud thermodynamic phase classification with three SWIR spectral bands",2019,"10.1117/1.JRS.13.034526","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073060574&doi=10.1117%2f1.JRS.13.034526&partnerID=40&md5=acc896d1a5cca2340a76345cd4a9e8b9","Knowing the thermodynamic phase of a cloud-whether it is composed of spherical water droplets or polyhedral ice crystals-is critical in remote sensing applications and in climate studies. Liquid water and ice have different absorptive properties in certain spectral bands that can be exploited to identify the phase of clouds using ground-based, passive remote sensing. Our simulations found that ground-based radiance measurements at three spectral channels (1.55, 1.64, and 1.70 μm) provide improved discrimination when analyzed in three spectral dimensions as opposed to previous approaches based in two-dimensional parameter space. Our simulations show that these bands provide good discrimination between liquid-water and ice clouds when the optical depth is large. We also show measurements from a ground-based spectrometer confirming the cloud-phase sensing ability of these three channels, with validation provided by a dual-polarization lidar system. © The Authors."
"57208534427;8058662600;7006728825;24764483400;7404021119;","How important are aerosol–fog interactions for the successful modelling of nocturnal radiation fog?",2019,"10.1002/wea.3503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065032492&doi=10.1002%2fwea.3503&partnerID=40&md5=f6b027eb4227f26cad4ca6e6f5f27ec5","Forecasting and modelling fog formation, development, and dissipation is a significant challenge. Fog dynamics involve subtle interactions between small-scale turbulence, radiative transfer and microphysics. Recent studies have highlighted the role of aerosol and related cloud microphysical properties in the evolution of fog. In this article, we investigate this role using very high-resolution large eddy simulations coupled with a newly developed multi-moment cloud microphysics scheme (CASIM), which has been designed to model aerosol–cloud interactions. The simulation results demonstrate the sensitivity of the fog structure to the properties of the aerosol population (e.g. number concentration). This study also demonstrates the importance of the treatment of aerosol activation in fog formation and discusses future work required to improve the representation of aerosol–fog interactions for simulations of fog. © 2019 The Authors. Weather published by John Wiley & Sons Ltd on behalf of Royal Meteorological Society"
"55873602100;","Impact of El Niño-southern oscillation and sunspot activity on India’s climate",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068708930&partnerID=40&md5=9e453cef802b244ffc650ee2d12fc3ba","Among several factors of climate, the El Niño-Southern Oscillation (ENSO) and Sunspot cycles work on interannual to interdecadal scales and it is believed that while the El Niño–La Niña pressure seesaw of Pacific Ocean affects climate by altering global wind and rainfall patterns, the 11 years periodic variability of sunspot appearance bring changes in insolation and cloud formation. Thus, the role of these two climate forcings seems critical in pushing short term climatic variabilities. This study attempts to know the impact of these two climatic phenomena on temperature and rainfall patterns at regional scale and for the purpose the study considers India as the case. Analysis reveals that temperature show a good correlation with sunspot activities, while the effect of ENSO cycle on country`s rainfall is not very clear. However, India’s coastal states record a notable rise in temperatures during El-Niño phase of ENSO phenomenon and this may be the cause behind fragmented and uneven rainfall over the country during El-Niño years. © 2019, World Research Association. All rights reserved."
"34974404300;7005199903;23481412500;57203355317;57203354120;55515466000;57208818224;57209168440;","eCatch: Enabling collaborative fisheries management with technology",2019,"10.1016/j.ecoinf.2019.05.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065889661&doi=10.1016%2fj.ecoinf.2019.05.010&partnerID=40&md5=9b903207919e6a6cdb35a0238db47161","Modernizing data systems to inform collaborative management is critical to adaptively managing fisheries in an era of climate change. In 2006, The Nature Conservancy of California purchased 13 federal groundfish permits in California with the objective of managing the fishing and reporting activities in a manner that protected sensitive habitats and species. At that time, collecting data for this fishery was done with paper logbooks. This made queries and visualization that could inform management decisions towards our objective impossible in a timely manner. To solve this problem, we built successive software prototypes that leveraged location-aware mobile devices, cloud-based computing, and visualization and query of geographic data over the web. The resulting software, eCatch, enabled avoidance of sensitive species and habitats and quantitative reporting on performance metrics related to those activities. What started as a technology solution to a problem of timely scientific monitoring revealed collateral benefits of collaboration with the fishing industry and markets that support sustainable activities. © 2019"
"57195981086;57210785732;","Solar irradiance, climatic indicators and climate change – An empirical analysis",2019,"10.1016/j.asr.2019.03.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063144712&doi=10.1016%2fj.asr.2019.03.018&partnerID=40&md5=42d53d8dc02946b0eafbe7ae6f269a92","Since the Sun is the main source of energy for our planet therefore even a slight change in its output energy can make a huge difference in the climatic conditions of the terrestrial environment. The rate of energy coming from the Sun (solar irradiance) might affect our climate directly by changing the rate of solar heating of the Earth and the atmosphere and indirectly by changing the cloud forming processes. In the present paper, based on stability test of Vector Auto Regressive (VAR) model, we have used the impulse response functions and the variance decomposition method for the analysis of climate variability. We have examined the possible connections among the solar irradiance and some climate indicators, viz., the global temperature anomaly, the global mean sea level, the global sea-ice extent and the global precipitation anomaly occurred during last forty years (1978–2017). In our investigation, we have observed that the impact of solar irradiance on the global surface temperature level in next decade will increase by ∼4.7% while the global mean sea level will increase about 0.67%. In the meantime, we have noticed about 5.3% decrement in the global sea-ice extent for the next decade. In case of the global precipitation anomaly we have not observed any particular trend just because of the variable climatic conditions. We also have studied the effect of CO2 as anthropogenic forcing where we have observed that the global temperature in the next decade will increase by 2.7%; mean sea level will increase by 6.4%. Increasing abundance in CO2 will be responsible for about 0.43% decrease in the sea-ice extent while there will not be any change in the precipitation pattern. © 2019 COSPAR"
"35203870600;36705265400;55614754800;23970271800;6506594339;11939918300;","How organized is deep convection over Germany?",2019,"10.1002/qj.3552","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069891620&doi=10.1002%2fqj.3552&partnerID=40&md5=444e1cbe7e636956991305d4652f6be2","Deep moist convection shows a tendency to organize into mesoscale structures. To be able to understand the potential effect of convective organization on the climate, one needs first to characterize organization. In this study, we systematically characterize the organizational state of convection over Germany based on two years of cloud-top observations derived from the Meteosat Second Generation satellite and of precipitation cores detected by the German C-band radar network. The organizational state of convection is characterized by commonly employed organization indices, which are mostly based on the object numbers, sizes and nearest-neighbour distances. According to the organization index Iorg, cloud tops and precipitation cores are found to be in an organized state for 69% and 92% of the time, respectively. There is an increase in rainfall when the number of objects and their sizes increase, independently of the organizational state. Case-studies of specific days suggest that convectively organized states correspond to either local multi-cell clusters, with less numerous, larger objects close to each other, or to scattered clusters, with more numerous, smaller organized objects spread out over the domain. For those days, simulations are performed with the large-eddy model ICON with grid spacings of 625, 312 and 156 m. Although the model underestimates rainfall and shows a too large cold cloud coverage, the organizational state is reasonably well represented without significant differences between the grid spacings. © 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57052558900;8836278700;15846270900;","Recent Regime Shifts in Mineral Dust Trends over South Asia from Long-Term CALIPSO Observations",2019,"10.1109/TGRS.2019.2891338","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068219809&doi=10.1109%2fTGRS.2019.2891338&partnerID=40&md5=45997734d153ed621a5f61dc3ffaaf5b","Mineral dust aerosols have significant implications on the regional-hydroclimate, especially over the regions located downwind of dust sources. During the premonsoon season, much of South Asia is characterized by enhanced aerosol loading favored by the transport of mineral dust from the desert regions of West Asia/Northwest India. Vertically resolved backscatter measurements at dual polarization from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) are used to estimate the dust optical depth over the Indian region. Using a decade long data set of CALIOP observations, a shift in long-term trend of dust over the Northwest India, Indo-Gangetic Plain, and West Asia is demonstrated. The decreasing trend in dust loading over the Indian region reversed to increasing after 2013. The interannual variability in premonsoon dust optical depth over Northwest India is found to be associated with winter time rainfall. The interannual variation of tropospheric temperature anomalies over Northwest India did not show a direct correlation with mineral dust loading. © 1980-2012 IEEE."
"36706881700;57138743300;57209279709;56797160600;56195639700;7402179527;57209717059;55740539300;57190029731;56609369600;23020373800;","A novel method for estimating the vertical velocity of air with a descending radiosonde system",2019,"10.3390/rs11131538","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068530899&doi=10.3390%2frs11131538&partnerID=40&md5=a42b9002eacaab4e11de03ac7320f328","Knowledge of vertical air motion in the atmosphere is important for both meteorological and climate studies due to its impact on clouds, precipitation and the vertical transport of air masses, heat, momentum, and composition. The vertical velocity (VV) of air is among the most difficult and uncertain quantities to measure due to its generally small magnitude and high temporal and spatial variability. In this study, a descending radiosonde system is developed to derive VV at the low and middle troposphere in north China during the summer months. The VV is estimated from the difference between the observed radiosonde descent speed and the calculated radiosonde descent speed in still air based on the fluid dynamic principle. The results showed that the estimated VV generally ranged from -1 m/s to 1 m/s, accounting for 80.2% of data points. In convective conditions, a wider distribution of the VV was observed, which was skewed to large values relative to those in nonconvective conditions. The average VV throughout the entire profile was close to 0 m/s under nonconvective conditions. In contrast, distinctive vertical air motions below 5 km above the ground were recorded under convective activities. Vigorous air motions with an absolute VV > 2 m/s were occasionally observed and were often associated with the occurrence of cloud layers. Moreover, the detailed structure of the instant air motion near the cloud boundaries (i.e., top and base), with an absolute VV > 10 m/s in convective weather systems, was clearly revealed by this technique. The uncertainty estimation indicated that this method has the potential to capture and describe events with vertical air motions > 0.69 m/s, which is useful for a convective weather study. Further studies are required to carefully assess the accuracy and precision of this novel VV estimation technique. © 2019 by the authors."
"6603546080;55916098100;56537827700;48662824200;7006495234;","The inter-calibration of the DSCOVR EPIC imager with aqua-MODIS and NPP-VIIRS",2019,"10.3390/rs11131609","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068513988&doi=10.3390%2frs11131609&partnerID=40&md5=5cdcd9900bbcaa2325996aed68d1bd47","The Deep Space Climate Observatory (DSCOVR) through the earth polychromatic imaging camera (EPIC) continuously observes the illuminated disk from the Lagrange-1 point. The EPIC sensor was designed to monitor the diurnal variation of ozone, clouds, aerosols, and vegetation, especially those features that benefit from observation near-backscatter conditions. The EPIC sensor does not contain any onboard calibration systems. This study describes the inter-calibration of EPIC channels 5 (0.44 μm), 6 (0.55 μm), 7 (0.68 μm), and 10 (0.78 μm) with respect to Aqua-MODIS and NPP-VIIRS. The calibration is transferred using coincident ray-matched reflectance pairs over all-sky tropical ocean (ATO) and deep convective cloud (DCC) targets. A robust and automated image-alignment technique based on feature matching was formulated to improve the navigation quality of the EPIC images. The EPIC V02 dataset exhibits improved navigation over V01. As the visible channels display similar spatial features, a single visible channel can be used to co-register the remaining visible bands. The VIIRS-referenced EPIC ATO and DCC ray-matched calibration coefficients are within 0.3%. The EPIC four-year calibration trends based on VIIRS are within 0.15%/year. The MODIS-based EPIC calibration coefficients were compared against the Geogdzhayev and Marshak 2018 published calibration coeffcients and were found to be within 1.6%. © 2019 by the authors."
"56641506800;15127920200;56962788100;7005810184;57189850075;","Determination of vegetation thresholds for assessing land use and land use changes in Cambodia using the Google Earth Engine cloud-computing platform",2019,"10.3390/rs11131514","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068517042&doi=10.3390%2frs11131514&partnerID=40&md5=44a2b935745ca9cb9e20e5354e28e96c","As more data and technologies become available, it is important that a simple method is developed for the assessment of land use changes because of the global need to understand the potential climate mitigation that could result from a reduction in deforestation and forest degradation in the tropics. Here, we determined the threshold values of vegetation types to classify land use categories in Cambodia through the analysis of phenological behaviors and the development of a robust phenology-based threshold classification (PBTC) method for the mapping and long-termmonitoring of land cover changes. We accessed 2199 Landsat collections using Google Earth Engine (GEE) and applied the Enhanced Vegetation Index (EVI) and harmonic regression methods to identify phenological behaviors of land cover categories during the leaf-shedding phenology (LSP) and leaf-flushing phenology (LFS) seasons. We then generated 722mean phenology EVI profiles for 12 major land cover categories and determined the threshold values for selected land cover categories in the mid-LSP season. The PBTC pixel-based classified map was validated using very high-resolution (VHR) imagery. We obtained a cumulative overall accuracy of more than 88% and a cumulative overall accuracy of the referenced forest cover of almost 85%. These high accuracy values suggest that the very first PBTC map can be useful for estimating the activity data, which are critically needed to assess land use changes and related carbon emissions under the Reducing Emissions from Deforestation and forest Degradation (REDD+) scheme. We found that GEE cloud-computing is an appropriate tool to use to access remote sensing big data at scale and at no cost. © 2019 by the authors."
"57197747810;22980640400;","Application of sentinel-1 data for classifying croplands using Google earth engine",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073343208&partnerID=40&md5=5554cfd9e335fdf4fd1ab199333b0848","The agricultural sector is an important source of national income in many tropical countries, including Indonesia. Monitoring agricultural is essential to support the agricultural activities. However, these countries have tropical monsoon climate with heavy amounts of rainfall. Therefore, temporal monitoring using microwave remote sensing is beneficial to overcome the heavy cloud coverage, which is often an obstacle for applying optical remote sensing. Recently, the growing trend of cloud-based geospatial platforms, such as Google Earth Engine (GEE), provides processing tools and cloud storage for remote sensing data without high specification hardware. In this study, Sentinel-1 synthetic aperture radar (SAR) sensor data from 2017 and supplementary Sentinel-2 optical sensor data was obtained and processed in GEE to identify two types of cropping patterns in paddy fields and to classify agricultural croplands. Four types of polarization combination datasets and a random forest classifier set with number of trees to be 25 and 50 were used for the classification process. The classification results show that the VH, VV, and the subtraction of VH and VV polarization with a random forest of 50 trees was achieved with 76.88% of overall accuracy and the kappa value equaled 0.728. The random forest with 50 trees significantly increased the classification accuracy of the dataset with fewer band compositions. The Sentinel-1 images are believed to be satisfactorily accurate enough for agricultural cropland classification and are sufficient for identifying the two cropping patterns in paddy fields. © Geoinformatics International."
"12800533700;57195927161;25628949700;57188715522;6602319642;","Supporting microclimate modeling with 3D uas data acquisition",2019,"10.28974/idojaras.2019.3.2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075421902&doi=10.28974%2fidojaras.2019.3.2&partnerID=40&md5=a2f31fb946ddf111bf6c8673043f7fba","Microclimatic analysis of an urban scenario has always been an interesting but complicated challenge. The available remote sensing equipments ensure multi-or hyperspectral imagery being ready to extract excellent land cover information, but the obtained data have lower spatial resolution limiting the efficiency of such analyses. In order to increase the geometric resolution in microclimatic studies, an exercise was executed with an Unmanned Aerial System. The calibration of the imaging camera on a dedicated test field was followed by the data capture flight over the campus of the Budapest University of Technology and Economics. The evaluation of the acquired images has resulted a point cloud containing millions of points. The high density point cloud was able to be transformed into 3D mesh representation and could be fed into a geographic information system for further analysis steps. Based on the color and height information of all individual points, the obtained geometric base was easily to be converted into land cover model representing man-made and natural objects, like buildings or trees. The segmentation of the model is a suitable input for climatic analyses and simulation software packages, where extreme high geometric resolution is required. © 2019, Hungarian Meteorological Service. All rights reserved."
"55838309600;56727418600;7201920155;","Effect of adding hydrometeor mixing ratios control variables on assimilating radar observations for the analysis and forecast of a Typhoon",2019,"10.3390/atmos10070415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070556153&doi=10.3390%2fatmos10070415&partnerID=40&md5=28e020630a559c7119cb9ca5c0e60018","The variational data assimilation (DA) method seeks the optimal analyses by minimizing a cost function with respect to control variables (CVs). CVs are extended in this study to include hydrometeor mixing ratios related variables besides the widely used sets of CVs (momentum fields, surface pressure, temperature, and pseudo-relative humidity). The impacts of the extra CVs are investigated in terms of hydrometeor mixing ratios to the assimilation of radar radial velocity (Vr) and reflectivity (RF) for the analysis and prediction of Typhoon Chanthu (2010). It is found that the background error statistics of the extended CVs from the National Meteorological Center (NMC) method is reliable. The track forecast is improved significantly by including hydrometeor mixing ratios as CVs to assimilate radar Vr and RF. The DA experiments using the hydrometer CVs show much improved intensity analysis and forecast. It also improves the precipitation forecast skills to some extent. The positive impact is significant using a direct RF assimilation scheme, when Vr and RF data are applied together. It suggests that when we applying an indirect RF assimilation scheme, the fitting of more hydrometers in the cost function will tend to cause a slight degradation for other variables such as the wind and temperature. © 2019 by the authors."
"56874860900;55148597900;56835489900;7006056992;34168121300;6602386601;","New evidence of glacier darkening in the Ortles-Cevedale group from Landsat observations",2019,"10.1016/j.gloplacha.2019.04.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064441150&doi=10.1016%2fj.gloplacha.2019.04.014&partnerID=40&md5=aa68eaebb12896800c9d21a73157a7d2","Glacier darkening, or the decrease in glacier albedo over time, has been reported for glaciers in several parts of the world. In this study, we use data from the Landsat archive spanning back to 1984 to investigate the long-term evolution of surface albedo in the ablation area of 15 selected glaciers in the Ortles-Cevedale group, Central Italian Alps, and determine rates and magnitude of darkening. We calculate albedo trends using all available images acquired between 1984 and 2011, by filtering for cloud and snow cover. To confirm that the trends are robust, we perform tests on three pseudo-invariant calibration sites located outside glaciers, ruling out an influence of sensor degradation or varying solar geometry. All 15 investigated glaciers show a decrease in the albedo, which is significant at the 95% (99%) confidence level for 14 (12) glaciers. Albedo trends range between −0.001 y−1 and −0.006 y−1, with an average of −0.003 y−1. We compare our results with previous research in the study area to evaluate the effects of increasing supraglacial debris and climate change on the decrease in albedo; the first appears particularly important for some glaciers and we hypothesize glacier darkening might be caused by a combination of these two factors. © 2019 Elsevier B.V."
"56089348800;7003991093;","Meridional structure and future changes of tropopause height and temperature",2019,"10.1002/qj.3587","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069833569&doi=10.1002%2fqj.3587&partnerID=40&md5=dfc42ff61b0d657d9f42cd82c8633ef5","We use a simple, semianalytic, column model to understand better the meridional structure of the tropopause height and future changes in its height and temperature associated with global warming. The model allows us to separate the effects of tropospheric lapse rate, optical depth, outgoing longwave radiation (OLR), and stratospheric cooling on the tropopause height. When applied locally at each latitudinal band, the model predicts the overall meridional structure of the tropopause height, with a tropical tropopause substantially higher than in higher latitudes and a sharp transition at the edge of the extratropics. The large optical depth of the Tropics, due mainly to the large water-vapour path, is the dominant tropospheric effect producing the higher tropical tropopause, whereas the larger tropical lapse rate actually acts to lower the tropopause height. The dynamical cooling induced by the stratospheric circulation lifts the thermal tropopause in the Tropics further, resulting in it being significantly cooler and higher than in mid- and high-latitudes. The model quantifies the causes of the tropopause height increase with global warming that is found robustly in climate integrations from the fifth Coupled Model Intercomparison Project (CMIP5). The large spread in the increase rate of tropopause height in the CMIP5 model is captured by the simple model, which attributes the dominant contributions to changes in water-vapour path and lapse rate, with changes in CO2 concentration and OLR having much smaller direct effects. The CMIP5 models also show a small but robust increase in the tropopause temperature in low latitudes, with a much smaller increase in higher latitudes. We suggest that the tropical increase may be caused at least in part by nongrey effects in the radiative transfer associated with the higher levels of water vapour in the Tropics, with near-constant tropopause temperatures predicted otherwise. © 2019 Royal Meteorological Society"
"51360903200;55622148300;","Modification of the wintertime Pacific–North American pattern related North American climate anomalies by the Asian–Bering–North American teleconnection",2019,"10.1007/s00382-018-4586-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058840316&doi=10.1007%2fs00382-018-4586-4&partnerID=40&md5=350d2a4f3f583ea7a87acaf709aefb68","The Pacific–North American (PNA) pattern is closely related to North American climate. In this study, we demonstrate that the PNA associated anomalies of North American surface temperatures and temperature extremes are modified by the extratropical Asian–Bering–North American (ABNA) teleconnection. The temperature and temperature extreme anomalies in association with the combination of the PNA and ABNA patterns are most prominent over the Canadian Prairies, and can be approximated by a linear superposition of the circulation and temperature responses to the two patterns. The various temperature responses result from the corresponding atmospheric circulation anomalies, which are associated with sea surface temperature and precipitation anomalies in the tropical eastern-central Pacific and snow cover anomalies in the Siberian region. In particular, pronounced circulation anomalies are apparent over the Great Lakes/Hudson Bay, and around the Aleutian Islands with opposite sign for the in-phase PNA and ABNA combination. This induces anomalous temperature advection and precipitation, as well as the heating associated variations of vertical motion and clouds, leading to prominent surface temperature anomalies over the Canadian Prairies directly through the variation of the surface energy budget. For the out-of-phase PNA and ABNA combination, the anomalous circulation center tends to be situated along the west coast of North America. This induces weak circulation anomalies over north-central North America and brings weak thermal advection and precipitation anomalies there, leading to insignificant temperature anomalies over the Canadian Prairies. Both the ABNA and PNA can be skillfully predicted on the seasonal time scale, as well as their pattern related North American temperature anomalies. Hence it is important to consider both tropical and extratropical sources of predictability in improving North American climate prediction skill on seasonal to interannual time scales. © 2018, The Author(s)."
"55535166800;56493740900;7403531523;6602844274;8272845400;","New Temporal and Spectral Unfiltering Technique for ERBE/ERBS WFOV Nonscanner Instrument Observations",2019,"10.1109/TGRS.2019.2891748","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068209075&doi=10.1109%2fTGRS.2019.2891748&partnerID=40&md5=f13d1168e2b9ea458f181703b2701d3b","Earth Radiation Budget Experiment (ERBE) Wide-Field-of-View (WFOV) nonscanner instrument onboard Earth Radiation Budget Satellite (ERBS) provided critical 15-year outgoing broadband irradiances at the top of atmosphere (TOA) from 1985 to 1999 for studying Earth's climate. However, earlier studies show that the uncertainty in this radiation data set (Ed3) is significantly higher after the Mt. Pinatubo eruption in 1991 and satellite battery issue in 1993. Furthermore, Lee et al. showed that the transmission of ERBS WFOV shortwave dome degraded due to exposure to direct sunlight. To account for this degradation, a simple time-dependent but spectral-independent correction model was implemented in the past. This simple spectral-independent model did not completely remove the shortwave sensor artifact as seen in the temporal growth of the tropical mean day-minus-night longwave irradiance. A new temporal-spectral-dependent correction model of shortwave dome transmissivity loss similar to that used in the Clouds and the Earth's Radiant Energy System (CERES) project is developed and applied to the 15-year ERBS WFOV data. This model is constrained by the solar transmission obtained from ERBS WFOV shortwave nonscanner instrument observations of the Sun during biweekly in-flight solar calibration events. This new model is able to reduce the reported tropical day-minus-night longwave irradiance trend by ≈34%. In addition, the slope of this new trend is observed to be consistent over different regions. The remaining trend is accounted using a postprocess Ed3Rev1 correction. Furthermore, the time series analysis of these data over the Libya-4 desert site showed that the shortwave data are stable to within 0.7%. © 1980-2012 IEEE."
"55531715700;","Innovative pheno-network model in estimating crop phenological stages with satellite time series",2019,"10.1016/j.isprsjprs.2019.04.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065619557&doi=10.1016%2fj.isprsjprs.2019.04.012&partnerID=40&md5=f2b3c0edc3b5835fdd3d0187f300688e","Large-scale remote monitoring of crop phenological development is vital for scheduling farm management activities and estimating crop yields. Tracking crop phenological progress is also crucial to understand agricultural responses to environmental stress and climate change. During the past decade, time series of remotely sensed imagery has been increasingly employed to monitor the seasonal growing dynamics of crops. A variety of curve-fitting based phenological methods have been developed to estimate critical phenological transition dates. However, those phenological methods are typically parametric by making mathematical assumptions of crop phenological processes and usually require year-long satellite observations for parameter training. The assumption and constraint make those methods inadequate for phenological monitoring in heavy cloud-contaminated regions or in complex agricultural systems. The objective of this study is to estimate crop phenological stages with satellite time series using a complex network-based phenological model (i.e., “pheno-network”). The innovative pheno-network model is non-parametric without mathematically defined phenological assumptions and can be constructed with partial-year remote sensing data. Rooted in network theory, the pheno-network model characterizes the complex phenological process with spectrally defined nodes and edges. It provides an innovative network representation to model the temporal dynamics of spectral reflectance of crops throughout the growing season. With corn and soybean in Illinois as a case study, the pheno-network model was devised to estimate their phenological transition dates along the leaf senescence trajectory from 2002 to 2017. Results indicated that the estimated transition dates of corn had strong correlation with its ground-observed mature stage. As for soybean, the estimated transition dates were closely associated with its dropping leaves stage. The pheno-network model shows marked potential to advance phenological monitoring in complex agricultural diversified and intensified systems. © 2019 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)"
"56690317100;26536184000;7005071296;37089364100;57211297978;55188253000;","X-band dual-polarization radar observations of snow growth processes of a severe winter storm: Case of 12 December 2013 in South Korea",2019,"10.1175/JTECH-D-18-0076.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073365460&doi=10.1175%2fJTECH-D-18-0076.1&partnerID=40&md5=89bcd701a51484fd170e881ca773b65c","The characteristics of microphysical processes of a severe winter storm that occurred on the Korean Peninsula on 12 December 2013 was studied in this work for the first time via X-band dual-polarization weather radar observations. A new range–height indicator (RHI) scan-based quasi-vertical profile methodology, in which polarimetric radar variables were averaged at each height of the RHI scan, was introduced to investigate the snow microphysics, and the obtained polarimetric radar signatures served as fingerprints of the dendritic growth, aggregation, and riming processes. Enhanced differential reflectivity (Zdr) and specific differential phase shift (Kdp) bands were detected near the-15°C isotherm,which signified the growth of dendrites or platelike crystals. The observed correlation between the increases in the reflectivity factor at horizontal polarization Zh and copolar correlation coefficient rhv and the decreases in Zdr and Kdp magnitudes at lower heights suggested the occurrence of the aggregation process. The combination of high Zh and low Zdr values with turbulent atmospheric conditions observed at the ground level indicated the occurrence of the riming process. In addition, the negative Kdp and Zdr values combined with high Zh and rhv magnitudes (observed near the end of the snow event) indicated the formation of graupel particles. The polarimetric radar signatures obtained for the snow growth processes were evident from ground observations and agreed well with the results of the Weather Research and Forecasting Model and Modern-Era Retrospective Analysis for Research and Applications data. Furthermore, the spatial variability of Zh methodology was implemented to describe both aggregates and rimed ice particles. © 2019 American Meteorological Society."
"57190809882;40661134200;56421015100;14920039400;36619804000;55869557800;","Regional response of winter snow cover over the Northern Eurasia to late autumn Arctic sea ice and associated mechanism",2019,"10.1016/j.atmosres.2019.02.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062150167&doi=10.1016%2fj.atmosres.2019.02.010&partnerID=40&md5=88eba9a38b4450999f22185f470517bb","Variations of sea ice can exert significant impacts on the atmospheric general circulation, temperature and precipitation, resulting in anomalous land surface conditions such as snow cover. In this study, we explored the possible impacts of the abnormal late autumn Arctic sea ice on winter snow depth over the Eurasia, especially the mechanism responsible for regional response of the snow cover to the sea ice anomalies through both observational analysis based on multi-source snow depth data and numerical sensitivity experiments. Results show that with decreasing sea ice in the Barents and Kara Seas (BKS) region, the snow depth exhibits evident regional responses, which are featured by decreased snow depth in the North Eurasia but increased in central Europe. Further analysis suggests that the Arctic Oscillation (AO) is an important connection between the BKS sea ice and anomalous winter snow depth, which affect both the temperature and the precipitation in winter over the Eurasia. The regional difference mainly comes from significant differences in regional atmospheric general circulation anomalies as well as the various controlling factors affecting the formation of the snowfall. In North Eurasia, water vapor plays a decisive role in the formation of the winter snowfall and further the winter snow depth. Positive (negative) BKS sea ice anomaly generally induces positive (negative) AO pattern, which can enhance (weaken) the zonal wind and increase (decrease) water vapor transportation to the North Eurasia, causing increased (decreased) winter snow depth. In contrast, in Europe, temperature is the dominant factor affecting the formation of the snowfall and the snow depth. Positive (negative) AO pattern, enhances (weakens) the warm moist advection and thus leads to increased (decreased) temperatures in the Europe, consequently resulting in reduced (increased) winter snow depth. © 2019 Elsevier B.V."
"56200927700;56068376200;57195136826;36705293400;7409390483;","The ‘two-way feedback mechanism’ between unfavorable meteorological conditions and cumulative PM2.5 mass existing in polluted areas south of Beijing",2019,"10.1016/j.atmosenv.2019.02.050","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063680108&doi=10.1016%2fj.atmosenv.2019.02.050&partnerID=40&md5=164d13af234fc6dd0e64a847653823a4","In winter, heavy aerosol pollution episodes (HPEs) occur frequently on the North China Plain (NCP) under unfavorable meteorological conditions. After the aerosol pollution with fine aerosol particles less than 2.5 μm (PM2.5) accumulates to a certain extent in Beijing and its vicinity (BIV), boundary-layer (BL) meteorological conditions worsen due to radiative cooling effects of aerosols, which further facilitate PM2.5 accumulation. This “two-way feedback mechanism” between unfavorable metrological conditions and cumulative PM2.5, particularly PM2.5 explosive growth with mass concentration doubled in several to 10 h, has been found in BIV. To investigate whether the two-way feedback exists on the southern NCP, we selected four representative cities with radiosonde observations, which lie south of Beijing and used PM2.5 data, radiation observations, and radiosonde data from December 2016 to the beginning of January 2017. We found that the two-way feedback existed in these four cities. In each city, HPEs included transport stages (TSs), during which relative strong winds transport pollutants into different regions, and cumulative stages (CSs), in which temperature inversions occur and became striking due to the radiative cooling effects of elevated aerosols under slight or calm winds. This would further cause an increase of PM2.5 concentration. During the CSs, growth of PM2.5 concentration was governed by the two-way feedback, which explained over 70% of the increase. During HPEs, warm and humid advection, topographic wind, longwave radiation at night were conducive to the inversion at the beginning of HPEs, but not dominant with respect to anomalous inversion in CSs. In addition, with the presence of supersaturated layers, aerosol would enter the cloud-fog system, which would reduce observed PM2.5 mass concentration to a certain degree. © 2019 The Author(s)"
"57189439781;6602809597;7102953444;6603693155;","Inter-hemispheric differences in energy budgets and cross-equatorial transport anomalies during the 20th century",2019,"10.1007/s00382-018-4572-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058625226&doi=10.1007%2fs00382-018-4572-x&partnerID=40&md5=3c6e04ec97296a9412817d2240c13876","We analyze the evolution of inter-hemispheric asymmetries in the energy budgets (EBs) and near-surface temperature anomalies during the 20th century, as given in Coupled Model Inter-comparison Project, phase 5 (CMIP5) simulations. We also consider the cross-equatorial energy transports (CET) in the atmosphere and in the oceans, in order to evidence how EB asymmetries affect the redistribution of energy between the two hemispheres. Two different experimental settings have been considered, one including only the spatially homogeneous evolving greenhouse gas forcing (GHG), and another one a realistic superposition of all known evolving forcings (ALL), such as aerosols and volcanic eruptions. This study shows that, according to the CMIP5 models, the response of the climate system to the ongoing forcing during the 20th century has differed substantially from what would have resulted from an increase in GHG concentration alone. In the GHG ensemble the Northern Hemisphere (NH) warms more than the Southern Hemisphere (SH), while both hemispheres exhibit similar and positive EB anomalies at the TOA, mainly due to increasing shortwave absorption and with no significant variations of cross-equatorial energy transports. On the contrary, in the ALL ensemble the two hemispheres warm similarly, while the SH exhibits a positive EB anomaly twice as large as in the NH, due to a reduced LW emission (Outgoing Longwave Radiation, OLR) in the SH, with oceanic CET anomalies directed towards the NH. The EB asymmetry in ALL is ascribed to the asymmetry in OLR changes, which is explained by the different role of clouds in the two hemispheres. The ocean heat content (OHC) tendency per unit surface area is similar in the two hemispheres, so that the asymmetries in ALL EB determine CET changes. We evidence that CET changes in the ALL ensemble are associated with the inter-hemispheric asymmetry in the aerosol forcing, which is stronger in the NH than in the SH. We find no significant relation between CETs and inter-hemispheric near-surface temperature asymmetries in GHG, partly due to the large model spread. Generally, deficits in modeled CET for present-day conditions are not ascribed to forcings and feedbacks, rather they are intrinsic to the models. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"7501630594;7201526685;57211067280;56467654300;7501956187;57195590180;57203887855;6603627233;","How much of Typhoon Morakot's extreme rainfall is attributable to anthropogenic climate change?",2019,"10.1002/joc.6030","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068045514&doi=10.1002%2fjoc.6030&partnerID=40&md5=efa2b4bc4f1f672fc6f236b0d77b90c2","Typhoon Morakot (2009), which made landfall in Taiwan during August 7–9, 2009, produced the highest rainfall and became the deadliest typhoon ever recorded in Taiwan since 1958. To assess the role of anthropogenic climate change in the typhoon-related torrent, we compare the water budget between a pair of cloud-resolving sensitivity experiments. The pair consists of a control simulation that reproduces Typhoon Morakot (2009) in current climate and a sensitivity simulation in which the same storm is placed in a slightly different climate background where the late 20th century anthropogenic climate change signal is removed. The anthropogenic signal is estimated with the CMIP5 experiments of 18 models for the period of 1985–2005, during which the global warming trend is discernible. In climate states that differ merely by a 20-year mean anthropogenic change, Morakot (2009) yields 3.4–3.6% more total rainfall in the control experiment than its sensitivity counterpart within a radius of 300–500 km from the storm centre. Water budget analysis indicates that the increase in typhoon rainfall is mainly resulted from the enhanced convergence of vapour flux. The enhancement is, in turn, contributed by the increased tropospheric moisture due to global warming and, to a lesser extent, by a more active secondary circulation in the storm that is associated with the anthropogenic climate change. © 2019 Royal Meteorological Society"
"57207697043;55766838600;56463154100;56539258900;57205085158;","Evaluation of the effects of a multiphysics ensemble on the simulation of an extremely hot summer in 2003 over the CORDEX-EA-II region",2019,"10.1002/joc.6028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062728517&doi=10.1002%2fjoc.6028&partnerID=40&md5=905d043ee7ffe0ed87a8b85e35b67a13","In this paper, we evaluate a 48-member multiphysics ensemble using the Weather Research and Forecasting (WRF) model for the JJA extreme precipitation and temperature in 2003 over the CORDEX-EA-II domain. The simulated precipitation and temperature are reasonable in the subregions controlled by a large-scale circulation, yet the biases for both precipitation and temperature are evident over the subregions where the effects of mesoscale processes are important. The performance of various combinations of WRF physical schemes for simulating the JJA precipitation is dependent on the region. Meanwhile, the cumulus and microphysical schemes have substantial influences on the simulation of precipitation, and the land surface models and cumulus schemes play crucial roles in the surface temperature. Our analysis shows that the combination of Noah for the land surface process, Lin for the microphysics, G3D for the cumulus parameterization, and CAM for the radiation scheme can provide the most reliable reproduction of both precipitation and temperature extremes over China. Ensemble analysis shows that the simulated climate extremes are usually accompanied by a large ensemble spread, implying sensitivities to the model physical processes in some subregions. The simulated wind fields at low-to-middle atmospheric levels display responses to the options of the land surface models and cumulus schemes. The essential impact of the land–atmospheric interaction on simulating the extremes can be largely attributed to the active convective processes. WRF has difficulties in reproducing the observed temporal evolution of the rainfall process, which consists of continuous large rainfall episodes in the observation data set during the simulation period. © 2019 Royal Meteorological Society"
"36011145800;7403681584;7003663939;6601970557;35386901400;7004210200;","Climatological influence of Eurasian winter surface conditions on the Asian and Indo-Pacific summer circulation in the NCEP CFSv2 seasonal reforecasts",2019,"10.1002/joc.6029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061909480&doi=10.1002%2fjoc.6029&partnerID=40&md5=2cad51b5b49937917d326bd49ca57875","This study evaluates the possible influence of the winter surface conditions in Eurasia on the summer circulation over the Asian continent and Indo-Pacific region. We have analysed multi-seasonal ensemble reforecasts for 30 years (1979–2008) using the National Centers for Environmental Prediction Climate Forecast System version 2 initialized at the beginning of each month from January to May. It is found that the reforecasts initialized in winter (e.g., February) overestimate the snow cover fraction, depth and water equivalent, as well as surface albedo in the excessively snow-covered portion of Eurasia from March to June. These biases are generated and perpetuated by a snow-albedo feedback, leading to excessive upwards shortwave radiation reflected from the overly snow-covered surface and an intense cold bias from the surface to mid-troposphere. Originating over land, the cold bias is extended eastwards over the northwestern North Pacific by the advection of prevailing westerly winds. The cold air temperature in the broad mid-latitude Asian-Pacific region causes significantly lower geopotential heights at pressure levels in the middle and upper troposphere and thus increases the upper-level westerly winds on its southern flank over the Asian continent and Indo-Pacific. A slower than observed snow melting rate helps the winter cold bias persists well into the summer season in these runs. As a result, compared with the reforecasts initialized in spring (e.g., May), winter-initialized reforecasts feature lower geopotential heights in the upper troposphere over Eurasia and a stronger subtropical jet over the Asian continent and the North Pacific from May to September, especially in early summer. The CFSv2 reforecasts in both sets of cases have too little total cloud fraction over Eurasia during June–August, leading to enhanced downwards shortwave radiation. © 2019 Royal Meteorological Society"
"36095558300;37068471000;7005528388;","Band-by-Band Contributions to the Longwave Cloud Radiative Feedbacks",2019,"10.1029/2019GL083466","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067886695&doi=10.1029%2f2019GL083466&partnerID=40&md5=50c2cee9b043c54a0f065d9a50e8484f","Cloud radiative feedback is central to our projection of future climate change. It can be estimated using the cloud radiative kernel (CRK) method or adjustment method. This study, for the first time, examines the contributions of each spectral band to the longwave (LW) cloud radiative feedbacks (CRFs). Simulations of three warming scenarios are analyzed, including +2 K sea surface temperature, 2 × CO2, and 4 × CO2 experiments. While the LW broadband CRFs derived from the CRK and adjustment methods agree with each other, they disagree on the relative contributions from the far-infrared and window bands. The CRK method provides a consistent band-by-band decomposition of LW CRF for different warming scenarios. The simulated and observed short-term broadband CRFs for the 2003–2013 period are similar to the long-term counterparts, but their band-by-band decompositions are different, which can be further related to the cloud fraction changes in respective simulations and observation. ©2019. American Geophysical Union. All Rights Reserved."
"57193385740;7401796996;57210350827;57202754759;8629713500;56638409500;57203030873;6701430830;35209683700;","Thicker Clouds and Accelerated Arctic Sea Ice Decline: The Atmosphere-Sea Ice Interactions in Spring",2019,"10.1029/2019GL082791","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067971362&doi=10.1029%2f2019GL082791&partnerID=40&md5=774fd9d3ea0061aa03db80e029872f05","Observations show that increased Arctic cloud cover in the spring is linked with sea ice decline. As the atmosphere and sea ice can influence each other, which one plays the leading role in spring remains unclear. Here we demonstrate, through observational data diagnosis and numerical modeling, that there is active coupling between the atmosphere and sea ice in early spring. Sea ice melting and thus the presence of more open water lead to stronger evaporation and promote cloud formation that increases downward longwave flux, leading to even more ice melt. Spring clouds are a driving force in the disappearance of sea ice and displacing the mechanism of atmosphere-sea ice coupling from April to June. These results suggest the need to accurately model interactions of Arctic clouds and radiation in Earth System Models in order to improve projections of the future of the Arctic. ©2019. American Geophysical Union. All Rights Reserved."
"8846887600;7102447698;","The Importance of Sampling Variability in Assessments of ENSO-PM2.5 Relationships: A Case Study for the South Central United States",2019,"10.1029/2019GL082250","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067933243&doi=10.1029%2f2019GL082250&partnerID=40&md5=2098a77d5b597c3e8242eebd62945882","We assess seasonal mean relationships between the El Niño–Southern Oscillation (ENSO) and surface fine particulate matter (PM2.5) over the United States using observations from 1999 to 2015. Through a case study of the springtime PM2.5 response to ENSO in the South Central United States, we demonstrate that sampling variability is large on the 17-year time scale of the observations, leading to large uncertainty in the estimated relationships. The PM2.5 response in the South Central United States is dominated by decreases in soil dust concentrations during El Niño, which we link to changes in cloud cover and near-surface wind speed. The observed dust response during 1999–2015 is about 25% stronger than the long-term mean ENSO-forced signal estimated from climate model control simulations. Given a different 17-year period, this discrepancy could be even larger. Our findings underscore the importance of accounting for sampling uncertainty in studies of ENSO's air quality impacts. ©2019. American Geophysical Union. All Rights Reserved."
"6701832491;56577620100;57195906298;56298802300;6507733066;6701915334;57207008570;","Arctic Summer Sea Ice Melt and Related Atmospheric Conditions in Coupled Regional Climate Model Simulations and Observations",2019,"10.1029/2018JD030207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067465353&doi=10.1029%2f2018JD030207&partnerID=40&md5=544a6990ca7c239e881a4c11f9a742aa","Observations from 1979 to 2014 show a positive trend in the summer sea ice melt rate with an acceleration particularly in June and August. This is associated with atmospheric circulation changes such as a tendency toward a dipole pattern in the mean sea level pressure (SLP) trend with an increase over the Arctic Ocean and a decrease over Siberia. Consistent with previous studies, we here show the statistical relationship between the summer sea ice melt rate and SLP and that more than one SLP pattern is associated with anomalously high melt rates. Most high melt rates occur during high pressure over the Arctic Ocean accompanied by low pressure over Siberia, but a strong Beaufort High and advection of warm air associated with a cyclone located over the Taymyr Peninsula can also trigger anomalous high ice melt. We evaluate 10-member ensemble simulations with the coupled atmosphere-ice-ocean Arctic regional climate model HIRHAM-NAOSIM. The simulations have systematically low acceleration of sea ice melt rate in August, related to shortcomings in representing the strengthening pressure gradient from the Barents/Kara Sea toward Northern Greenland in recent decades. In general, the model shows the same classification of SLP patterns related to anomalous melt rates as the observations. However, the evolution of sea ice melt-related cloud-radiation feedback over the summer reveals contrary effects from low-level clouds in the reanalysis and in the simulations. © 2019. American Geophysical Union. All Rights Reserved."
"55918845300;12783789800;36718923100;23006105100;35758966700;7101760779;57203148324;","Late quaternary climate variability at mfabeni peatland, eastern south africa",2019,"10.5194/cp-15-1153-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068141349&doi=10.5194%2fcp-15-1153-2019&partnerID=40&md5=1aa85dfa5603e54c9bb6087518b1b7c1","The scarcity of continuous, terrestrial, palaeoenvironmental records in eastern South Africa leaves the evolution of late Quaternary climate and its driving mechanisms uncertain. Here we use a 7m long core from Mfabeni peatland (KwaZulu-Natal, South Africa) to reconstruct climate variability for the last 32 000 years (cal ka BP).We infer past vegetation and hydrological variability using stable carbon (δ13Cwax) and hydrogen isotopes (δDwax) of plant-wax n-Alkanes and use Paq to reconstruct water table changes. Our results indicate that late Quaternary climate in eastern South Africa did not respond directly to orbital forcing or to changes in sea-surface temperatures (SSTs) in the western Indian Ocean. We attribute the arid conditions evidenced at Mfabeni during the Last Glacial Maximum (LGM) to low SSTs and an equatorward displacement of (i) the Southern Hemisphere westerlies, (ii) the subtropical high-pressure cell, and (iii) the South Indian Ocean Convergence Zone (SIOCZ), which we infer was linked to increased Antarctic sea-ice extent. The northerly location of the high-pressure cell and the SIOCZ inhibited moisture advection inland and pushed the rain-bearing cloud band north of Mfabeni, respectively. The increased humidity at Mfabeni between 19 and 14 cal kyr BP likely resulted from a southward retreat of the westerlies, the high-pressure cell, and the SIOCZ, consistent with a decrease in Antarctic sea-ice extent. Between 14 and 5 cal kyr BP, when the westerlies, the high-pressure cell, and the SIOCZ were in their southernmost position, local insolation became the dominant control, leading to stronger atmospheric convection and an enhanced tropical easterly monsoon. Generally drier conditions persisted during the past ca. 5 cal ka BP, probably resulting from an equatorward return of the westerlies, the high-pressure cell, and the SIOCZ. Higher SSTs and heightened El Niño-Southern Oscillation (ENSO) activity may have played a role in enhancing climatic variability during the past ca. 5 cal ka BP. Our findings highlight the influence of the latitudinal position of the westerlies, the high-pressure cell, and the SIOCZ in driving climatological and environmental changes in eastern South Africa. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License."
"6603382350;57209471004;57190209035;16316664600;56298802300;6701832491;","Validation of the sea ice surface albedo scheme of the regional climate model HIRHAM-NAOSIM using aircraft measurements during the ACLOUD/PASCAL campaigns",2019,"10.5194/tc-13-1695-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068139912&doi=10.5194%2ftc-13-1695-2019&partnerID=40&md5=de9235dc7c1148c711695781ffbdaa28","For large-scale and long-term Arctic climate simulations appropriate parameterization of the surface albedo is required. Therefore, the sea ice surface (SIS) albedo parameterization of the coupled regional climate model HIRHAM-NAOSIM was examined against broadband surface albedo measurements performed during the joint ACLOUD (Arctic CLoud Observations Using airborne measurements during polar Day) and PASCAL (Physical feedbacks of Arctic boundary layer, Sea ice, Cloud and AerosoL) campaigns, which were performed in May-June 2017 north of Svalbard. The SIS albedo parameterization was tested using measured quantities of the prognostic variables surface temperature and snow depth to calculate the surface albedo and the individual fractions of the ice surface subtypes (snow-covered ice, bare ice, and melt ponds) derived from digital camera images taken on board the Polar 5 and 6 aircraft. The selected low-altitude (less than 100 m) flight sections of overall 12 flights were performed over surfaces dominated by snow-covered ice. It was found that the range of parameterized SIS albedo for individual days is smaller than that of the measurements. This was attributed to the biased functional dependence of the SIS albedo parameterization on temperature. Furthermore, a time-variable bias was observed with higher values compared to the modeled SIS albedo (0.88 compared to 0.84 for 29 May 2017) in the beginning of the campaign, and an opposite trend towards the end of the campaign (0.67 versus 0.83 for 25 June 2017). Furthermore, the surface type fraction parameterization was tested against the camera image product, which revealed an agreement within 1 %. An adjustment of the variables, defining the parameterized SIS albedo, and additionally accounting for the cloud cover could reduce the root-mean-squared error from 0.14 to 0.04 for cloud free/broken cloud situations and from 0.06 to 0.05 for overcast conditions. © Author(s) 2019."
"56366861100;57089760800;9234008000;57206751038;57204075782;57196371292;55767580000;16023556800;7005312540;","Relationship analysis of PM2.5 and boundary layer height using an aerosol and turbulence detection lidar",2019,"10.5194/amt-12-3303-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067789696&doi=10.5194%2famt-12-3303-2019&partnerID=40&md5=d8ce0e4a1ae1dc0277f86b5ec3d77606","The atmospheric boundary layer height (BLH) is a key parameter in weather forecasting and air quality prediction. To investigate the relationship between BLH and air pollution under different conditions, a compact micro-pulse lidar integrating both direct-detection lidar (DDL) and coherent Doppler wind lidar (CDWL) has been built. This hybrid lidar is operated at 1.5 μm, which is eye-safe and made of all-fibre components. The BLH can be determined from aerosol density and vertical wind independently. During a 45 h continuous observation in June 2018, the stable boundary layer, residual layer and convective boundary layer are identified. The fine structure of the aerosol layers, drizzles and vertical wind near the cloud base are also detected. In comparison, the standard deviation between BLH values derived from DDL and CDWL is 0.06 km, indicating the accuracy of this work. The retrieved convective BLH is a little higher than that from ERA5 reanalysis due to different retrieval methods. Correlation between different BLH and PM2.5 is strongly negative before a precipitation event and becomes much weaker after the precipitation. Different relationships between PM2.5 and BLH may result from different BLH retrieval methods, pollutant sources and meteorological conditions. © 2019 Author(s)."
"57195947660;57014229800;56383436000;57204700515;7203052598;6701481359;","Formation of Light-Absorbing Organosulfates during Evaporation of Secondary Organic Material Extracts in the Presence of Sulfuric Acid",2019,"10.1021/acsearthspacechem.9b00036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067666547&doi=10.1021%2facsearthspacechem.9b00036&partnerID=40&md5=e73d015723748c3044786fcb013c9414","Organic aerosols affect the climate by scattering or absorbing incoming solar radiation. Secondary organic material (SOM), which represents the major chemical constituent of atmospheric aerosol particles, is produced by the oxidation of atmospheric volatile organic compounds (VOCs). SOM in clouds, fogs, and aerosols undergoes concentration/dilution cycles due to the evaporation/condensation of water droplets. These physical processes could lead to the chemical processing of SOM and the formation of new, light-absorbing compounds. In this study, model SOM was generated through smog chamber photooxidation and flow tube ozonolysis of various atmospherically relevant anthropogenic and biogenic VOCs, including toluene (TOL), d-limonene (LIM), α-pinene (APIN), β-pinene (BPIN), and isoprene (ISO). Collected SOM was extracted in water, and the solutions were acidified with sulfuric acid to pH 2 and dried to simulate the evaporation of acidic particles containing SOM. Significant changes in mass absorption coefficients (MACs) were observed after the evaporation and redissolution of SOM in the presence of sulfuric acid. At visible wavelengths, the MAC values of most SOM increased after the evaporation, with the fractional increase being the largest for LIM/O3 SOM at 400 nm (fractional increase of 65.0). Exceptions to evaporation increasing MAC values in the presence of sulfuric acid were ISO/OH and TOL/OH/NOx. Light-absorbing species in LIM/O3 SOM were chromatographically separated and detected using a photodiode array detector and a high-resolution electrospray ionization mass spectrometer. The increase in MAC was accompanied by the appearance of more than 300 organosulfate peaks. Five potential brown carbon (BrC) chromophores in LIM/O3 SOM were separated and assigned chemical formulas, including C10H16SO6, C10H14SO6, C10H16SO5, C11H16SO7, and C11H18SO8. This study suggests that evaporation-driven processes may occur in the atmosphere, substantially modifying the molecular composition and optical properties of SOM. The evaporation of filter extracts from the field or laboratory could similarly produce organosulfates as artifacts if the extract is sufficiently acidic before the evaporation. We recommend that complete drying of particulate matter filter extracts should be avoided in future work. © 2019 American Chemical Society."
"55706282100;57192695511;57191341169;55638979500;57203174863;7404548584;55476786400;24578264300;7004174939;","Detecting layer height of smoke aerosols over vegetated land and water surfaces via oxygen absorption bands: Hourly results from EPIC/DSCOVR in deep space",2019,"10.5194/amt-12-3269-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067692382&doi=10.5194%2famt-12-3269-2019&partnerID=40&md5=0d91af46e21fc874b393157e9666dd62","We present an algorithm for retrieving aerosol layer height (ALH) and aerosol optical depth (AOD) for smoke over vegetated land and water surfaces from measurements of the Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR). The algorithm uses Earth-reflected radiances in six EPIC bands in the visible and near-infrared and incorporates flexible spectral fitting that accounts for the specifics of land and water surface reflectivity. The fitting procedure first determines AOD using EPIC atmospheric window bands (443, 551, 680, and 780 nm), then uses oxygen (O2) A and B bands (688 and 764 nm) to derive ALH, which represents an optical centroid altitude. ALH retrieval over vegetated surface primarily takes advantage of measurements in the O2 B band. We applied the algorithm to EPIC observations of several biomass burning events over the United States and Canada in August 2017. We found that the algorithm can be used to obtain AOD and ALH multiple times daily over water and vegetated land surface. Validation is performed against aerosol extinction profiles detected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and against AOD observed at nine Aerosol Robotic Network (AERONET) sites, showing, on average, an error of 0.58 km and a bias of -0:13 km in retrieved ALH and an error of 0.05 and a bias of 0.03 in retrieved AOD. Additionally, we show that the aerosol height information retrieved by the present algorithm can potentially benefit the retrieval of aerosol properties from EPIC's ultraviolet (UV) bands. © 2019 The Author(s)."
"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)."
"37762151700;8536879900;55946097300;35189317300;7005632987;","Characterisation of aerosol constituents from wildfires using satellites and model data: a case study in Knysna, South Africa",2019,"10.1080/01431161.2019.1573338","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060934520&doi=10.1080%2f01431161.2019.1573338&partnerID=40&md5=23dbae858acbfa655c3866683a750253","Strong winds and dry conditions make it difficult to contain wild fires worldwide. Such fires could cause devastating effects on landscape structures around many urban/peri-urban areas. The greater impact of such fires is commonly felt when landscape elements such as forest vegetation biomass fuel increase the wild fire risk to people and their properties. In order to mitigate the impact of a wild fire at local level, it is imperative to understand its spatial distribution and fuel load dynamics surrounding it. This study aimed at exploring the possibility of integrating various satellites and model data to characterise the aerosols emissions from wild fires which occurred at Knysna (South Africa). The Moderate Resolution Imaging Spectroradiometer (MODIS), the Sentinel-2 normalized difference vegetation index (NDVI), the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), the Hybrid Single-Particle Lagrangian Intergrated trajectory (HYSPLIT) model and the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) model were employed to characterise the Knysna fires, and the resultant atmospheric conditions that prevailed at altitudes lower than 10 km. Large flames and high amounts of smoke were observed at the Knysna forests by the Sentinel-2 optical data. Our findings showed that there was an apparent reduction in the green vegetation biomass coverage of up to 20.2% following the wildfires as observed by Sentinel-2 data analysis. Biomass burning (BB) aerosols and smoke were observed to reach high altitudes of 2–4 km by CALIPSO. Pyrocumulus clouds were also observed at altitudes of 7.2 km. These clouds were a result of the mixing of the smoke and clouds in the mid-troposphere. The HYSPLIT model and MERRA-2 model showed that the emitted BB aerosols and smoke did not travel inland but rather dispersed in an eastward and south-eastward direction into the Indian Ocean from the source. A multi-satellite data approach proved to be a valuable resource to study the extent of wild fires and to determine their atmospheric impact and thus contributing to climate change. The transport models data was resourceful in determining the destination of the wild fires emissions. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group."
"57200689841;55917446200;55838951000;23090602200;","Contrasting meteorological drivers of the glacier mass balance between the Karakoram and central Himalaya",2019,"10.3389/feart.2019.00107","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068445302&doi=10.3389%2ffeart.2019.00107&partnerID=40&md5=aa42e13293772657d9bb049aa6251e9d","There is strong variation in glacier mass balances in High Mountain Asia. Particularly interesting is the fact that glaciers are in equilibrium or even gaining mass in the Karakoram and Kunlun Shan ranges, which is in sharp contrast with the negative mass balances in the rest of High Mountain Asia. To understand this difference, an in-depth understanding of the meteorological drivers of the glacier mass balance is required. In this study, two catchments in contrasting climatic regions, one in the central Himalaya (Langtang) and one in the Karakoram (Shimshal), are modeled at 1 km grid spacing with the numerical atmospheric model WRF for the period of 2011–2013. Our results show that the accumulation and melt dynamics of both regions differ due to contrasting meteorological conditions. In Shimshal, 92% of the annual precipitation falls in the form of snow, in contrast with 42% in Langtang. In addition, 80% of the total snow falls above an altitude of 5000 m a.s.l, compared with 35% in Langtang. Another prominent contrast is that most of the annual snowfall falls between December and May (71%), compared with 52% in Langtang. The melt regimes are also different, with 41% less energy available for melt in Shimshal. The melt in the Karakoram is controlled by net shortwave radiation (r = 0.79 ± 0.01) through the relatively low glacier albedo in summer, while net longwave radiation (clouds) dominates the energy balance in the Langtang region (r = 0.76 ± 0.02). High amounts of snowfall and low melt rates result in a simulated positive glacier surface mass balance in Shimshal (+0.31 ± 0.06 m w.e. year−1) for the study period, while little snowfall, and high melt rates lead to a negative mass balance in Langtang (−0.40 ± 0.09 m w.e. year−1). The melt in Shimshal is highly variable between years, and is especially sensitive to summer snow events that reset the surface albedo. We conclude that understanding glacier mass balance anomalies requires quantification and insight into subtle shifts in the energy balance and accumulation regimes at high altitude and that the sensitivity of glaciers to climate change is regionally variable. © 2019 Bonekamp, de Kok, Collier and Immerzeel."
"57192919839;6507121473;54380076600;7003696133;6701834052;57205682408;13403622000;57189498750;","A Process Study on Thinning of Arctic Winter Cirrus Clouds With High-Resolution ICON-ART Simulations",2019,"10.1029/2018JD029815","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067503395&doi=10.1029%2f2018JD029815&partnerID=40&md5=6315ff87adb5aedfeaf9ac9c46bb13e4","In this study, cloud-resolving simulations of a case study for a limited area of the hibernal Arctic were performed with the atmospheric modeling system ICON-ART (ICOsahedral Nonhydrostatic-Aerosol and Reactive Trace gases). A thorough comparison with data both from satellite as well as aircraft measurement is presented to validate the simulations. In addition, the model is applied to clarify the microphysical processes occurring when introducing artificial aerosol particles into the upper troposphere with the aim of modifying cirrus clouds in the framework of climate engineering. Former modeling studies investigating the climate effect of this method were performed with simplifying assumptions and much coarser resolution, reaching partly contradicting conclusions concerning the method's effectiveness. The primary effect of seeding is found to be a reduction of ice crystal number concentrations in cirrus clouds, leading to increased outgoing longwave radiative fluxes at the top of the atmosphere, thereby creating a cooling effect. Furthermore, a secondary effect is found, as ice crystals formed from the injected seeding aerosol particles lead to enhanced riming of cloud droplets within the planetary boundary layer. This effectively reduces the coverage of mixed-phase clouds, thus generating additional cooling by increased upward longwave radiative fluxes at the surface. The efficacy of seeding cirrus clouds proves to be relatively independent from the atmospheric background conditions, scales with the number concentrations of seeding particles, and is highest for large aerosol particles. ©2019. The Authors."
"57209409693;55717074000;","Dust Radiative Effects on Climate by Glaciating Mixed-Phase Clouds",2019,"10.1029/2019GL082504","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067703001&doi=10.1029%2f2019GL082504&partnerID=40&md5=2d34481697d089178addafe1692c3374","Mineral dust plays an important role in the primary formation of ice crystals in mixed-phase clouds by acting as ice nucleating particles (INPs). It can influence the cloud phase transition and radiative forcing of mixed-phase clouds, both of which are crucial to global energy budget and climate. In this study, we investigate the dust indirect effects on mixed-phase clouds through heterogeneous ice nucleation with the U.S. Department of Energy (DOE) Energy Exascale Earth System Model (E3SM). Dust and INP concentrations simulated from two versions of E3SM with three ice nucleation parameterizations were evaluated against observations in the Northern Hemisphere. Constrained by these observations, E3SM shows that dust INPs induce a global mean net cloud radiative effect of 0.05 to 0.26 W/m2 with the predominant warming appearing in the Northern Hemisphere midlatitudes. However, a cooling effect is found in the Arctic due to reduced longwave cloud forcing. ©2019. American Geophysical Union. All Rights Reserved."
"56001394200;56044817200;6701853567;","Climate Responses to the Splitting of a Supercontinent: Implications for the Breakup of Pangea",2019,"10.1029/2018GL081510","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067670246&doi=10.1029%2f2018GL081510&partnerID=40&md5=56a1db1fe437990d8a940d6690086c51","Reconstructing deep time climate often relies on a limited number of data points, which can hinder inference of the large-scale climate state. Here we use an Earth system model with idealized boundary conditions to simulate climate responses to paleogeographic changes associated with the breakup of a supercontinent. After the supercontinent splits, weaker tropical easterlies occur in the larger ocean basin, which dampens the Walker circulation and warms the equatorial ocean through reduced upwelling. Additionally, cloud formation increases across the midlatitude ocean, causing locally cooler sea surface temperatures. Over land, there is dramatic tropical cooling post breakup due to enhanced moisture and cloud formation. Consequently, the latitudinal temperature gradient responses over land and ocean oppose each other, which makes inferring large scale climate changes from spatially spare proxy records particularly challenging in this scenario. Our findings emphasize the tight coupling between geography and planetary scale climate dynamics in the tropics and subtropics. ©2019. American Geophysical Union. All Rights Reserved."
"7006263321;","An Observational Constraint on CMIP5 Projections of the East African Long Rains and Southern Indian Ocean Warming",2019,"10.1029/2019GL082847","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067648490&doi=10.1029%2f2019GL082847&partnerID=40&md5=d33481e56d4bcbe99309ba6dacf0c86e","Two outlying projections of the East African Long Rains suggest the seasonal rainfall may double by the late 21st century. Previous work has linked these extremes—found in the IPSL-CM5A model—to an exceptional March to May warming of the southern Indian Ocean. The current study shows a strong feedback between sea surface temperature (SST) increases and reduced low-level cloud cover (with similar behavior in other southern subtropical oceans). An observational constraint is developed by demonstrating a correlation across 28 models between the strength of present-day interannual SST-cloud sensitivity and future SST response. Verification of the present-day sensitivity finds that IPSL-CM5A's feedbacks are very likely overestimated. It is therefore suggested its projections should be discounted for the March to May southern Indian Ocean and East African Long Rains. This narrows the CMIP5 plausible range of Long Rains totals by a third. ©2019. The Authors."
"6602164207;55766197400;57207482495;57192063251;57206613939;55664151400;","An Examination of Temperature Trends at High Elevations Across the Tibetan Plateau: The Use of MODIS LST to Understand Patterns of Elevation-Dependent Warming",2019,"10.1029/2018JD029798","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067380609&doi=10.1029%2f2018JD029798&partnerID=40&md5=323629fad43a5f9d6701372f6e86482d","Research has revealed systematic changes in warming rates with elevation (EDW) in mountain regions. However, weather stations on the Tibetan plateau are mostly located at lower elevations (3,000-4,000 m) and are nonexistent above 5,000 m, leaving critical temperature changes unknown. Satellite LST (Land Surface Temperature) can fill this gap but needs calibrating against in situ air temperatures (Tair). We develop a novel statistical model to convert LST to Tair, developed at 87 high-elevation Chinese Meteorological Administration stations. Tair (daily maximum/minimum temperatures) is compared with Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua LST (1330 and 0130 local time) for 8-day composites during 2002-2017. Typically, 80-95% of the difference between LST and Tair (ΔT) is explained using predictors including LST diurnal range, morning heating/nighttime cooling rates, the number of cloud free days/nights, and season (solar angle). LST is corrected to more closely represent Tair by subtracting modeled ΔT. We validate the model using an AWS on Zhadang Glacier (5800 m). Trend analysis at the 87 stations (2002-2017) shows corrected LST trends to be similar to original Tair trends. To examine regional contrasts in EDW patterns, elevation profiles of corrected LST trends are derived for three ranges (Qilian Mountains, NyenchenTanglha, and Himalaya). There is limited EDW in the Qilian mountains. Maximum warming is observed around 4,500-5,500 m in NyenchenTanglha, consistent with snowline retreat. In common with other studies, there is stabilization of warming at very high elevations in the Himalaya, including absolute cooling above 6,000 m, but data there are compromised by frequent cloud. ©2019. The Authors."
"57209329947;6602523027;7005870626;55372492800;7005601996;7403063262;","Impact of Air Pollution Controls on Radiation Fog Frequency in the Central Valley of California",2019,"10.1029/2018JD029419","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067400167&doi=10.1029%2f2018JD029419&partnerID=40&md5=8c92b5834b2c72ddaf232fa637439b00","In California's Central Valley, tule fog frequency increased 85% from 1930 to 1970, then declined 76% in the last 36 winters. Throughout these changes, fog frequency exhibited a consistent north-south trend, with maxima in southern latitudes. We analyzed seven decades of meteorological data and five decades of air pollution data to determine the most likely drivers changing fog, including temperature, dew point depression, precipitation, wind speed, and NOx (oxides of nitrogen) concentration. Climate variables, most critically dew point depression, strongly influence the short-term (annual) variability in fog frequency; however, the frequency of optimal conditions for fog formation show no observable trend from 1980 to 2016. NOx concentration, which has a decreasing north-south concentration gradient, declined continuously over this period, consistent with the long-term temporal and spatial trends in fog. As development in the Central Valley increased direct particle and other pollutant emissions from 1930 to 1970, fog frequency increased. Following the Clean Air Act, particle emissions quickly declined, and NOx emissions declined steadily, reducing the cloud condensation nuclei (CCN) available for fog formation. As a precursor of ammonium nitrate aerosols, which are efficient CCN, we used NOx measurements and emission trends as a proxy for the CCN trend. We conclude that while the short-term fog variability is dominantly driven by climate fluctuations, the longer-term temporal and spatial changes in fog have been driven by changes in air pollution. For conditions close to the dew point, a decrease in fog of 5 days/year per 10 parts per billion NOx decrease occurred across the Central Valley. ©2019. American Geophysical Union. All Rights Reserved."
"57216608274;55053999400;","Recent decadal variability of daily observed temperatures in Hindukush, Karakoram and Himalaya region in northern Pakistan",2019,"10.1007/s00382-018-4557-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058008515&doi=10.1007%2fs00382-018-4557-9&partnerID=40&md5=73670d3568185f65d71bf06e2528b814","Spatiotemporal variability in the observed daily temperatures for a recent 30-year period (1986–2015) is examined from a total of 18 different weather stations in the Hindukush, Karakoram and Himalaya region in northern Pakistan (HKNP) by employing probability distribution functions (PDFs) on annual and seasonal basis. The region is a hub of glaciers and perennial snow cover which fulfills a large fraction of Pakistan’s water demand for irrigation, power generation and for drinking purposes. The temperature-based PDFs show a significant mean decadal warming of 0.45 °C, 0.03 °C, and 0.25 °C, in the maximum (Tmax), minimum (Tmin) and mean temperature (Tmean) of the region, on annual basis, respectively. However, the observed river discharges-based PDFs of the region show a mean negative decadal shift of − 40.15 m3/s on annual basis. The negative decadal shift in river discharge in warm climate is discussed in terms of percentile-based analysis which quantifies temperature changes for each percentile. The results revealed that the decadal changes in Tmin percentiles are more correlated with river discharge than decadal changes in Tmax and Tmean percentiles, on annual basis. The seasonal analysis showed a significant positive decadal shift of 1.93 °C for Tmax in spring season, whereas winter season showed a significant negative decadal shift of − 0.56 °C in Tmin of the HKNP region, from first decade (1986–1995) to third decade (2006–2015), respectively. The rest of seasons (i.e., summer and autumn) displayed high variability in the Tmax, Tmin and Tmean in the HKNP region. A high observed (non-parametric) correlation between the observed cloud cover and temperatures of the region indicates that changes in regional cloud cover may influence the regional temperatures. This work highlights the importance of recent temperature variations in the HKNP and its connection with the downstream river discharge of the region in changing climate of northern Pakistan. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"56711441000;57191226379;55717074000;8437626600;42962694100;57207200838;57204630338;57204634290;55577875600;57206903444;57191227191;57192212652;36958464800;55606974300;57206768200;57201942906;","Seasonal climatic effects and feedbacks of anthropogenic heat release due to global energy consumption with CAM5",2019,"10.1007/s00382-018-4528-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056457116&doi=10.1007%2fs00382-018-4528-1&partnerID=40&md5=3589326eb83e4d0abcea7e0764f728e7","Anthropogenic heat release (AHR) is the heat generated in global energy consumption, which has not been considered in global climate models generally. The global high-resolution AHR from 1992 to 2013, which is estimated by using the Defense Meteorological Satellite Program (DMSP)/Operational Linescan System (OLS) satellite data, is implemented into the Community Atmosphere Model version 5 (CAM5). The seasonal climatic effects and possible feedbacks of AHR are examined in this study. The modeling results show that AHR increases the global annual mean surface temperature and land surface temperature by 0.02 ± 0.01 K (1σ uncertainty) and 0.05 ± 0.02 K (1σ uncertainty), respectively. The global climatic effect of AHR varies with season: with a stronger climatic effect in the boreal winter leading to global mean land surface temperature increases by 0.10 ± 0.01 K (1σ uncertainty). In the selected regions (40°N–60°N, 0°E–45°E) of Central and Western Europe the average surface temperature increases by 0.46 K in the boreal summer, and in the selected regions (45°N–75°N, 30°E–140°E) of northern Eurasia the average surface temperature increases by 0.83 K in the boreal winter. AHR changes the height and thermodynamic structure of the global planetary boundary layer, as well as the stability of the lower troposphere, which affects the global atmospheric circulation and low cloud fraction. In addition, at the surface both the shortwave radiation flux in the boreal summer and the down-welling longwave flux in the boreal winter change significantly, as a result of the change in low clouds caused by the effect of AHR. This study suggests a possible new mechanism of AHR effect on global climate through changing the global low-cloud fraction, which is crucial for global energy balance, by modifying the thermodynamic structure and stability of the lower troposphere. Thus this study improves our understanding of the global climate change caused by human activities. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"57196718266;35350641800;56915435100;7006069664;","Moisture flux adjustments in RegCM4 for improved simulation of Indian summer monsoon precipitation",2019,"10.1007/s00382-018-4564-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058171960&doi=10.1007%2fs00382-018-4564-x&partnerID=40&md5=1a1ff797a6afc48594316e56c31751d1","The complexity of the Indian summer monsoon precipitation makes it’s prediction a challenging task as it is not only influenced by the large-scale flows but also by the micro-scale features. In a dynamical model, precipitation is resulted from the formation of clouds. The cloud formation and its processes occur at a micro scale. Current state-of-the-art dynamical models lack proper representation of the cloud processes, particularly at high resolutions for which the cloud processes are parameterized, thereby poorly resolving the precipitation. This study aims at examining the impact of the cloud parameters on the simulation of Indian summer monsoon precipitation in Regional Climate Model version 4 (RegCM4). The autoconversion coefficient which determines the conversion of cloud water into precipitation in the Explicit Moisture Convergence scheme is adjusted in the RegCM4. The impact of autoconversion is experimented with ten different values and it is found that it has a significant effect on the simulation of precipitation during summer monsoon season. The experiments are conducted by changing autoconversion from 1.5 × 10−4 to 7.5 × 10−4/s along with the default value of 2.5 × 10−4/s. On changing the autoconversion values from 60 to 300% of the default value, the precipitation pattern improves over most parts of India. The model simulates the rainfall better when the autoconversion coefficient is changed to 7.5 × 10−4/s. With the best outcome with the adjusted autoconversion and control configuration, the model is simulated for seventeen monsoon seasons and the analyses of RegCM4 simulated vertically integrated moisture transport, convective available potential energy and atmospheric moisture budget suggest that the model efficacy is enhanced in higher autoconversion value than the control one. Statistical evaluations using bias, correlation coefficients, comprehensive rating matrices and skill score confirm the suitability of higher autoconversion rate for summer monsoon simulations. The model with adjusted autoconversion coefficient (at 7.5 × 10−4/s) has improved the representation of seasonal precipitation distribution and its year-to-year variation including other derived features. The rainfall pattern is improved over North West India and North East India especially, the monsoon core regions. The mean seasonal rainfall is in phase 94% of the time with the modeler-adjusted moisture as compared to 82% in the control in the long term simulation. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"57202977053;57209296376;57201667638;56544915700;26030052000;15923105200;","A high-speed particle phase discriminator (PPD-HS) for the classification of airborne particles, as tested in a continuous flow diffusion chamber",2019,"10.5194/amt-12-3183-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067259848&doi=10.5194%2famt-12-3183-2019&partnerID=40&md5=ff24ecdc6e7bba88bf2dde7df78ee37f","A new instrument, the High-speed Particle Phase Discriminator (PPD-HS), developed at the University of Hertfordshire, for sizing individual cloud hydrometeors and determining their phase is described herein. PPD-HS performs an in situ analysis of the spatial intensity distribution of near-forward scattered light for individual hydrometeors yielding shape properties. Discrimination of spherical and aspherical particles is based on an analysis of the symmetry of the recorded scattering patterns. Scattering patterns are collected onto two linear detector arrays, reducing the complete 2-D scattering pattern to scattered light intensities captured onto two linear, one-dimensional strips of light sensitive pixels. Using this reduced scattering information, we calculate symmetry indicators that are used for particle shape and ultimately phase analysis. This reduction of information allows for detection rates of a few hundred particles per second. Here, we present a comprehensive analysis of instrument performance using both spherical and aspherical particles generated in a well-controlled laboratory setting using a vibrating orifice aerosol generator (VOAG) and covering a size range of approximately 3-32 μm. We use supervised machine learning to train a random forest model on the VOAG data sets that can be used to classify any particles detected by PPD-HS. Classification results show that the PPD-HS can successfully discriminate between spherical and aspherical particles, with misclassification below 5% for diameters >3μm. This phase discrimination method is subsequently applied to classify simulated cloud particles produced in a continuous flow diffusion chamber setup. We report observations of small, near-spherical ice crystals at early stages of the ice nucleation experiments, where shape analysis fails to correctly determine the particle phase. Nevertheless, in the case of simultaneous presence of cloud droplets and ice crystals, the introduced particle shape indicators allow for a clear distinction between these two classes, independent of optical particle size. From our laboratory experiments we conclude that PPD-HS constitutes a powerful new instrument to size and discriminate the phase of cloud hydrometeors. The working principle of PPD-HS forms a basis for future instruments to study microphysical properties of atmospheric mixed-phase clouds that represent a major source of uncertainty in aerosol-indirect effect for future climate projections.. © Author(s) 2019."
"57201642187;36917387900;57204531901;7005350396;","Role of cumulus parameterization on the seasonal and diurnal precipitation over Southeast Asia in RegCM4",2019,"10.1007/s00382-018-4517-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055967288&doi=10.1007%2fs00382-018-4517-4&partnerID=40&md5=42cdf3c9abe3c05eb0d0c257b2755564","This study examines the sensitivity of the seasonal mean and diurnal precipitation simulated by the Regional Climate Model version 4 (RegCM4) to cumulus parameterization in the Southeast Asia (SEA) domain. Based on the same lateral boundary conditions from the interim European Centre for Medium-Range Weather Forecast reanalysis data (ERA-interim), RegCM4 integrations using the Emanuel cumulus convection scheme over all grid boxes in the model (EE), and those using the Emanuel (Grell) scheme in ocean (land) areas (referred to as the mixed scheme, or MC) were carried out at a 50 km × 50 km horizontal resolution in the period of 2000–2010. It was found that both MC and EE have comparable performance in capturing the mean circulation features in SEA during boreal summer. Simulations based on EE tend to produce a seasonal wet bias over South China Sea (SCS). In comparison, while the mean rainfall over SCS and east of the Philippines is improved by the use of MC, conditions in western coastal IndoChina become too wet. For the diurnal cycle (DC) of precipitation, it was reasonably well captured by both cumulus schemes; however, in comparison to EE, MC consistently underestimates the DC amplitude. Empirical Orthogonal Function (EOF) analyses revealed that, while the first leading mode of diurnal rainfall was reproduced by both schemes, the second mode was suppressed in the MC simulations. In particular, this mode corresponds to the afternoon rainfall over inland locations including western IndoChina and southeastern China. MC tends to produce more cloudy conditions, cooler surface air temperature and hence a more stable environment and weaker convection at 1200–1500 local time in these locations. Over the Maritime Continent, the second mode is associated with evening-to-midnight rainfall peaks in the mountain ranges of Sumatra, Borneo and New Guinea. There is weaker orographic precipitation at 1800–0000 local time by MC compared to EE, associated with weaker diurnal convergence and upward motion as well as a drier environment in the MC simulations. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"57209311540;8231500200;55402394300;","Chemistry and deposition in the model of atmospheric composition at global and regional scales using inversion techniques for trace gas emissions (magritte v1.1)-part 1: Chemical mechanism",2019,"10.5194/gmd-12-2307-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067314656&doi=10.5194%2fgmd-12-2307-2019&partnerID=40&md5=d9351f41ec20cef126c8a00713ec3fe1","A new chemical mechanism for the oxidation of biogenic volatile organic compounds (BVOCs) is presented and implemented in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace gas Emissions (MAGRITTE v1.1). With a total of 105 organic species and over 265 gas-phase reactions, 69 photodissociations, and 7 heterogeneous reactions, the mechanism treats the chemical degradation of isoprene-its main focus-as well as acetaldehyde, acetone, methylbutenol, and the family of monoterpenes. Regarding isoprene, the mechanism incorporates a state-of-The-Art representation of its oxidation scheme accounting for all major advances put forward in recent theoretical and laboratory studies. The recycling of OH radicals in isoprene oxidation through the isomerization of Z-Î-hydroxyperoxy radicals is found to enhance OH concentrations by up to 40 % over western Amazonia in the boundary layer and by 10 %-15 % over the southeastern US and Siberia in July. The model and its chemical mechanism are evaluated against the suite of chemical measurements from the SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) airborne campaign, demonstrating a good overall agreement for major isoprene oxidation products, although the aerosol hydrolysis of tertiary and non-Tertiary nitrates remain poorly constrained. The comparisons for methylnitrate indicate a very low nitrate yield (
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., 21ĝ 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 -3 ĝC, similarly to the onset temperature from Pseudomonas syringae. 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.
The high concentrations of INPs at warmer ice nucleation temperatures (
In this work, the mineralogy and mixing state of the fine fraction (<2.5 μm) in laboratory-suspended dust from PSAs in north Africa were made using novel techniques with online single-particle mass spectrometry (SPMS) and traditional offline scanning electron microscopy (SEM). A regional difference in mineralogy was detected, with material sourced from Morocco containing a high number fraction of illite-like particles in contrast to Sahelian material which contains potassium- and sodium-depleted clay minerals like kaolinite. Single-particle mixing state had a much greater local variation than mineralogy, particularly with respect to organic-biological content. Applying the same methods to ambient measurement of transported dust in the marine boundary layer at Cabo Verde in the remote North Atlantic enabled the number fractions of illite/smectite clay mineral (ISCM), non-ISCM and calcium-containing particles to be reported at a 1 h time resolution over a 20-day period. Internal mixing of silicate particles with nitrate, chlorine and organic-biological material was also measured and compared to that in the suspended soils.
The results show SPMS and SEM techniques are complementary and demonstrate that SPMS can provide a meaningful high-resolution measurement of single-particle mineralogy and mixing state in laboratory and ambient conditions. In most cases, the differences in the mineralogical composition between particles within a soil sample were small. Thus, particles were not composed of discrete mineral phases. In ambient measurements, the ISCM and nitrate content was found to change significantly between distinct dust events, indicating a shift in source and transport pathways which may not be captured in offline composition analysis or remote sensing techniques. © 2019. This work is distributed under the Creative Commons Attribution 4.0 License." "6507781926;6507589406;","Long-term responses of mountain forests to environmental change in West-Central Mexico",2019,"10.1007/s10113-018-1435-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056300147&doi=10.1007%2fs10113-018-1435-2&partnerID=40&md5=9046c5aa350fee4e6418d3787ecdc2e1","This study is an important contribution to the International Long-term Ecological Research Network (ILTER), because it presents the local responses of soil and plant composition to global and regional climatic oscillations of the last millennia in Mexico. Mountain forests are ecosystems that have been constantly threatened by both anthropogenic and climate disturbances, mainly over the Late Holocene. By using palaeoecological techniques with fossil pollen and geochemical elements as proxies, this study incorporates the relationship of trees, herbs and epiphytes with dry and humid climate events. High-temporal resolution in the chronologies allowed the assessment of vegetation changes (every ~ 30 years) and soil geochemical elements in three forests located close (< 8 km) to each other. Our results showed that pine forest contracted along the dry periods of the Little Ice Age (AD 1350–1850), the Medieval Climate Anomaly (AD 800 to 1200) and the Late Classic Drought (AD 600 to 800). However, it expanded in the humid period (AD 1200 to 1350). Cloud forest was the most susceptible ecosystem to the above climate anomalies; trees contracted in periods of aridity and expanded in humid periods. The signature for the transitional forest was confounding: trees increased partially in both dry and humid periods with a well-correlated decrease in epiphytes. Soil losses were common in dry periods while fires increased along the last ~ 300 years. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "57206729590;21743348300;7801561771;7102674341;7102578937;6701410329;","A cloud identification algorithm over the Arctic for use with AATSR-SLSTR measurements",2019,"10.5194/amt-12-1059-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061924101&doi=10.5194%2famt-12-1059-2019&partnerID=40&md5=8632234e74d4071cab5faef5b6a8529a","The accurate identification of the presence of cloud in the ground scenes observed by remote-sensing satellites is an end in itself. The lack of knowledge of cloud at high latitudes increases the error and uncertainty in the evaluation and assessment of the changing impact of aerosol and cloud in a warming climate. A prerequisite for the accurate retrieval of aerosol optical thickness (AOT) is the knowledge of the presence of cloud in a ground scene. In our study, observations of the upwelling radiance in the visible (VIS), near infrared (NIR), shortwave infrared (SWIR) and the thermal infrared (TIR), coupled with solar extraterrestrial irradiance, are used to determine the reflectance. We have developed a new cloud identification algorithm for application to the reflectance observations of the Advanced Along-Track Scanning Radiometer (AATSR) on European Space Agency (ESA)-Envisat and Sea and Land Surface Temperature Radiometer (SLSTR) on board the ESA Copernicus Sentinel-3A and -3B. The resultant AATSR- SLSTR cloud identification algorithm (ASCIA) addresses the requirements for the study AOT at high latitudes and utilizes time-series measurements. It is assumed that cloudfree surfaces have unchanged or little changed patterns for a given sampling period, whereas cloudy or partly cloudy scenes show much higher variability in space and time. In this method, the Pearson correlation coefficient (PCC) parameter is used to measure the ""stability"" of the atmosphere-surface system observed by satellites. The cloud-free surface is classified by analysing the PCC values on the block scale 25×25 km 2 . Subsequently, the reflection at 3.7 μm is used for accurate cloud identification at scene level: with areas of either 1×1 or 0:5×0:5 km 2 . The ASCIA data product has been validated by comparison with independent observations, e.g. surface synoptic observations (SYNOP), the data from AErosol RObotic NETwork (AERONET) and the following satellite products: (i) the ESA standard cloud product from AATSR L2 nadir cloud flag; (ii) the product from a method based on a clear-snow spectral shape developed at IUP Bremen (Istomina et al., 2010), which we call ISTO; and (iii) the Moderate Resolution Imaging Spectroradiometer (MODIS) products. In comparison to ground-based SYNOP measurements, we achieved a promising agreement better than 95% and 83% within ±2 and ±1 okta respectively. In general, ASCIA shows an improved performance in comparison to other algorithms applied to AATSR measurements for the identification of clouds in a ground scene observed at high latitudes. © Author(s) 2019." "56724051400;8686475900;","Substantial Reductions in Cloud Cover and Moisture Transport by Dynamic Plant Responses",2019,"10.1029/2018GL081236","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061668418&doi=10.1029%2f2018GL081236&partnerID=40&md5=cdc3e73217d9efdd24b09963d73697f9","Cumulus clouds make a significant contribution to the Earth's energy balance and hydrological cycle and are a major source of uncertainty in climate projections. Reducing uncertainty by expanding our understanding of the processes that drive cumulus convection is vital to the accurate identification of future global and regional climate impacts. Here we adopt an interdisciplinary approach that integrates interrelated scales from plant physiology to atmospheric turbulence. Our explicit simulations mimic the land-atmosphere approach implemented in current numerical weather prediction, and global climate models enable us to conclude that neglecting local plant dynamic responses leads to misrepresentations in the cloud cover and midtropospheric moisture convection of up to 21% and 56%, respectively. Our approach offers insights into the key role played by the active vegetation on atmospheric convective mixing that has recently been identified as the source of half of the variance in global warming projections (i.e., equilibrium climate sensitivity). ©2019. The Authors." "56707853300;8211380400;56900416800;55234835700;56888211000;57195958231;","Evaluating the Response of Summertime Surface Sulfate to Hydroclimate Variations in the Continental United States: Role of Meteorological Inputs in the GEOS-Chem Model",2019,"10.1029/2018JD029693","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061064615&doi=10.1029%2f2018JD029693&partnerID=40&md5=acd77973f55d13fad0f2b0624f6cb976","Understanding the response of sulfate to climate change is crucial given tight couplings between sulfate and the hydrological cycle. As the sources and sinks of sulfate are sensitive to cloud and precipitation processes, the accuracy of model simulations depends on the accuracy of these meteorological inputs. In this study, we evaluate the GEOS-Chem model in simulating summertime surface sulfate concentrations in the continental United States across different levels of dryness and compare the model performance based on two sets of meteorological fields: Modern Era Retrospective Analysis for Research and Applications (MERRA) and MERRA-2. Both simulations fail to reproduce observed increases in sulfate during drought, as indicated by negative correlation slopes between surface sulfate concentrations and the standardized precipitation evapotranspiration index (SPEI). This deficiency can be largely attributed to too large a decrease in clouds and hence aqueous phase sulfate production as conditions shift from wet to dry. MERRA-2-driven GEOS-Chem (M2GC) shows improvements in cloud and precipitation fields relative to the MERRA-driven GEOS-Chem, hence eliminating approximately half of the bias in the simulated sulfate-SPEI slope. However, M2GC still underestimates boundary layer cloud fraction, overestimates liquid water content, and overestimates the rates of the decrease in both quantities as conditions become drier. Explicitly correcting these cloud biases in M2GC results in a 60–80% reduction of the bias in the simulated sulfate-SPEI slope. The strong sensitivity of simulated sulfate to prescribed cloud fields suggests the need for more comprehensive assessment of cloud inputs for sulfate simulations under current and future climate change scenarios. ©2019. American Geophysical Union. All Rights Reserved." "56417341400;16636807900;26536569500;","FAT or FiTT: Are Anvil Clouds or the Tropopause Temperature Invariant?",2019,"10.1029/2018GL080096","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061436550&doi=10.1029%2f2018GL080096&partnerID=40&md5=fbbc9d185b1bc30a5fbab2c10fb77fdd","The Fixed Anvil Temperature (FAT) hypothesis proposes that upper tropospheric cloud fraction peaks at a special isotherm that is independent of surface temperature. It has been argued that a FAT should result from simple ingredients: Clausius-Clapeyron, longwave emission from water vapor, and tropospheric energy and mass balance. Here the first cloud-resolving simulations of radiative-convective equilibrium designed to contain only these basic ingredients are presented. This setup does not produce a FAT: the anvil temperature varies by about 40% of the surface temperature range. However, the tropopause temperature varies by only 4% of the surface temperature range, which supports the existence of a Fixed Tropopause Temperature (FiTT). In full-complexity radiative-convective equilibrium simulations, the spread in anvil temperature is smaller by about a factor of 2, but the tropopause temperature remains more invariant than the anvil temperature by an order of magnitude. In other words, our simulations have a FiTT, not a FAT. ©2019. American Geophysical Union. All Rights Reserved." "7202463361;6602338213;7102862273;6506180220;7004692414;7006838702;7005284903;57204252724;35734944400;23485571500;57205141282;8850861200;","Year-Round In Situ Measurements of Arctic Low-Level Clouds: Microphysical Properties and Their Relationships With Aerosols",2019,"10.1029/2018JD029802","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061597757&doi=10.1029%2f2018JD029802&partnerID=40&md5=a9c9a5ed146864386b30702b22abeb4a","Two years of continuous in situ measurements of Arctic low-level clouds have been made at the Mount Zeppelin Observatory (78°56′N, 11°53′E), in Ny-Ålesund, Spitsbergen. The monthly median value of the cloud particle number concentration (N c ) showed a clear seasonal variation: Its maximum appeared in May–July (65 ± 8 cm −3 ), and it remained low between October and March (8 ± 7 cm −3 ). At temperatures warmer than 0 °C, a clear correlation was found between the hourly N c values and the number concentrations of aerosols with dry diameters larger than 70 nm (N 70 ), which are proxies for cloud condensation nuclei (CCN). When clouds were detected at temperatures colder than 0 °C, some of the data followed the summertime N c to N 70 relationship, while other data showed systematically lower N c values. The lidar-derived depolarization ratios suggested that the former (CCN-controlled) and latter (CCN-uncontrolled) data generally corresponded to clouds consisting of supercooled water droplets and those containing ice particles, respectively. The CCN-controlled data persistently appeared throughout the year at Zeppelin. The aerosol-cloud interaction index (ACI = dlnN c /(3dlnN 70 )) for the CCN-controlled data showed high sensitivities to aerosols both in the summer (clean air) and winter–spring (Arctic haze) seasons (0.22 ± 0.03 and 0.25 ± 0.02, respectively). The air parcel model calculations generally reproduced these values. The threshold diameters of aerosol activation (D act ), which account for the N c of the CCN-controlled data, were as low as 30–50 nm when N 70 was less than 30 cm −3 , suggesting that new particle formation can affect Arctic cloud microphysics. ©2019. The Authors." "57205701587;6603699044;35494005000;","Characteristics of Sea-Effect Clouds and Precipitation Over the Sea of Japan Region as Observed by A-Train Satellites",2019,"10.1029/2018JD029586","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061188532&doi=10.1029%2f2018JD029586&partnerID=40&md5=8e8eeb7dd8c5049373d2be2a079dac85","Prolific winter (December-January-February) snowfall occurs over northwest Japan due to frequent sea-effect precipitation that develops during cold-air outbreaks over the Sea of Japan (SOJ). Knowledge of sea-effect clouds and precipitation across the SOJ region has historically been constrained, however, by limited offshore in situ observations and remote-sensing limitations. This paper uses sensors from National Aeronautics and Space Administration (NASA)'s A-Train Satellite Constellation to examine winter sea-effect properties in the SOJ region. The analysis shows that cloud and precipitation occurrence generally increases across the SOJ from Asia to Japan, as potential sea-effect periods with an along-orbit mean sea surface to 850-hPa temperature difference ≥13 °C comprise a majority of the total clouds and precipitation. Sea-effect clouds and precipitation occur most frequently in an arc-shaped area that extends from the western SOJ, where the Japan-Sea Polar-Airmass Convergence Zone (JPCZ) is common, to the coast of Honshu, and then northward to Hokkaido. Radar, lidar, and column water path statistics along A-Train orbital tracks show that sea-effect precipitation is deepest along the central Honshu coast and becomes shallower but more frequent with northward extent. Precipitation amount and frequency maximize along the coast and adjacent mountains but decline with inland extent, most abruptly downstream of higher mountain barriers. This work illustrates that air-sea interactions, coastal geometry, and regional topography strongly modulate cloud and precipitation patterns during sea-effect periods in the SOJ region. ©2019. American Geophysical Union. All Rights Reserved." "15765916800;6603581315;7004707500;","The Influence of Competing Hydroclimate Processes on Stable Isotope Ratios in Tropical Rainfall",2019,"10.1029/2018GL080188","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061067155&doi=10.1029%2f2018GL080188&partnerID=40&md5=7f7bf279d9733b0d3d3abc91c2c23b60","In tropical paleoclimate studies, paleo-precipitation is often reconstructed from proxies via the “amount effect,” that is, the empirical inverse relationship between local precipitation amount (P) and the oxygen isotopic composition of precipitation (δ 18 O P ). However, recent research has illustrated numerous microphysical and dynamical controls on δ 18 O P that do not necessarily covary with P, complicating the reconstruction of circulation features like the Intertropical Convergence Zone. Here we introduce a new conceptual and statistical model for δ 18 O P that better captures the physical foundations for δ 18 O P as a tracer of hydrological balance. We find that bulk precipitation microphysics and cloud type exert comparable influences on δ 18 O P . Moisture transport plays an important secondary role in regions of deep atmospheric convection such as the Intertropical Convergence Zone and Indo-Pacific Warm Pool. Our findings help reconcile conflicting interpretations of Intertropical Convergence Zone excursions, and provide a firm physical grounding for more nuanced, accurate interpretations of past hydroclimate using water isotope proxies. ©2019. American Geophysical Union. All Rights Reserved." "7202304406;8060634600;15050523700;15047538100;7103352790;","On unravelling mechanism of interplay between cloud and large scale circulation: a grey area in climate science",2019,"10.1007/s00382-018-4211-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045469032&doi=10.1007%2fs00382-018-4211-6&partnerID=40&md5=29cac1aaf54a046daf4a64ba8b9515bd","The interaction between cloud and large scale circulation is much less explored area in climate science. Unfolding the mechanism of coupling between these two parameters is imperative for improved simulation of Indian summer monsoon (ISM) and to reduce imprecision in climate sensitivity of global climate model. This work has made an effort to explore this mechanism with CFSv2 climate model experiments whose cloud has been modified by changing the critical relative humidity (CRH) profile of model during ISM. Study reveals that the variable CRH in CFSv2 has improved the nonlinear interactions between high and low frequency oscillations in wind field (revealed as internal dynamics of monsoon) and modulates realistically the spatial distribution of interactions over Indian landmass during the contrasting monsoon season compared to the existing CRH profile of CFSv2. The lower tropospheric wind error energy in the variable CRH simulation of CFSv2 appears to be minimum due to the reduced nonlinear convergence of error to the planetary scale range from long and synoptic scales (another facet of internal dynamics) compared to as observed from other CRH experiments in normal and deficient monsoons. Hence, the interplay between cloud and large scale circulation through CRH may be manifested as a change in internal dynamics of ISM revealed from scale interactive quasi-linear and nonlinear kinetic energy exchanges in frequency as well as in wavenumber domain during the monsoon period that eventually modify the internal variance of CFSv2 model. Conversely, the reduced wind bias and proper modulation of spatial distribution of scale interaction between the synoptic and low frequency oscillations improve the eastward and northward extent of water vapour flux over Indian landmass that in turn give feedback to the realistic simulation of cloud condensates attributing improved ISM rainfall in CFSv2. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "57193718769;57203076700;55728284400;54079538100;55330583500;","Eastern equatorial Pacific sea surface temperature annual cycle in the Kiel Climate Model: simulation benefits from enhancing atmospheric resolution",2019,"10.1007/s00382-018-4233-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046638104&doi=10.1007%2fs00382-018-4233-0&partnerID=40&md5=744b261e6c7bda0f97563138a84be873","A long-standing difficulty of climate models is to capture the annual cycle (AC) of eastern equatorial Pacific (EEP) sea surface temperature (SST). In this study, we first examine the EEP SST AC in a set of integrations of the coupled Kiel Climate Model, in which only atmosphere model resolution differs. When employing coarse horizontal and vertical atmospheric resolution, significant biases in the EEP SST AC are observed. These are reflected in an erroneous timing of the cold tongue’s onset and termination as well as in an underestimation of the boreal spring warming amplitude. A large portion of these biases are linked to a wrong simulation of zonal surface winds, which can be traced back to precipitation biases on both sides of the equator and an erroneous low-level atmospheric circulation over land. Part of the SST biases also is related to shortwave radiation biases related to cloud cover biases. Both wind and cloud cover biases are inherent to the atmospheric component, as shown by companion uncoupled atmosphere model integrations forced by observed SSTs. Enhancing atmosphere model resolution, horizontal and vertical, markedly reduces zonal wind and cloud cover biases in coupled as well as uncoupled mode and generally improves simulation of the EEP SST AC. Enhanced atmospheric resolution reduces convection biases and improves simulation of surface winds over land. Analysis of a subset of models from the Coupled Model Intercomparison Project phase 5 (CMIP5) reveals that in these models, very similar mechanisms are at work in driving EEP SST AC biases. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "56134717100;57194834780;56046985600;57200270272;35547958400;","The fog regime in a tropical montane cloud forest in Brazil and its effects on water, light and microclimate",2019,"10.1016/j.agrformet.2018.11.030","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057547716&doi=10.1016%2fj.agrformet.2018.11.030&partnerID=40&md5=86aa03769ef1eaa34c7717aaceadfc25","Fog is a frequent phenomenon in tropical montane cloud forests (TMCFs). These ecosystems are important to the water supply of adjacent lowland regions which is largely determined by the effect of fog on TCMF evapotranspiration rates and hydrological balance. Understanding fog regimes at fine-grained temporal resolution is key to predict plant functioning and effects of climatic changes in TMCFs, especially on key hydrological services that these forests provide. Here, we combine a suite of micrometeorological and hydrological sensors with a visibilimeter, a reliable sensor of fog occurrence, to gather fine-grained information on fog frequency, duration and timing and its contribution to water inputs, light availability and microclimatic variability in a Brazilian TMCF. Despite occurring on 64% of days, fog was highly variable at daily and seasonal scales, occurring mostly at night and during the rainy season. Approximately 1200 liters of fog were intercepted per tree per year (259 mm or 10.7% of total net precipitation). Fog also increased net precipitation provided by concomitant fog-rain events. Monthly net precipitation to precipitation ratio, a measure of how much water arrives at the soil and how much evaporates or is intercepted by the canopy, was 0.96 - much higher than the 0.72 typical of lowland rainforest, due to the additional fog water input on TMCF. Cloudiness, and not fog, dominated light availability and inter-day microclimatic variability (air temperature and vapor pressure deficit). High fog regime variability indicates that understanding TMCFs functioning requires integration of plant function with fine-grained data of fog and cloud occurrence. We discuss possible consequences of our results to TMCFs plant functioning. © 2018 Elsevier B.V." "56883853200;57215596081;55338619800;56905611900;","Understanding the effect of an excessive cold tongue bias on projecting the tropical Pacific SST warming pattern in CMIP5 models",2019,"10.1007/s00382-018-4219-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059606248&doi=10.1007%2fs00382-018-4219-y&partnerID=40&md5=4d4f6c7e14ea1a475fa4af1399b5abac","An excessive cold tongue is a common bias among current climate models, and considered an important source of bias in projections of tropical Pacific climate change under global warming. Specifically, the excessive cold tongue bias is closely related to the tropical Pacific SST warming (TPSW) pattern. In this study, we reveal that two processes are the critical mechanisms by which the excessive cold tongue bias influences the projection of the TPSW pattern, based on 32 models from phase 5 of Coupled Model Intercomparison Projection (CMIP5). On the one hand, by assuming that the shortwave (SW) radiation to SST feedback is linearly correlated to the cold tongue SST, the excessive cold tongue bias can induce an overly weak negative SW–SST feedback in the central Pacific, which can lead to a positive SST warming bias in the central to western Pacific (around 150°E–140°W). Moreover, the overly weak local atmospheric dynamics response to SST is a key process of the overly weak SW–SST feedback, compared with the cloud response to atmospheric dynamics and the SW radiation response to cloud. On the other hand, the overly strong ocean zonal overturning circulation associated with the excessive cold tongue bias results in an overestimation of the ocean dynamical thermostat effect, with enhanced ocean stratification under global warming, leading to a negative SST warming bias in the central and eastern Pacific (around 170°W–120°W). These two processes jointly form a positive SST warming bias in the western Pacific, contributing to a La Niña-like warming bias. Therefore, we suggest a more realistic climatological cold tongue SST is needed for a more reliable projection of the TPSW pattern. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "57196736363;26221127400;17135775200;6507684871;23570956400;7005003889;57200805840;57215816112;55919261400;7006550959;55637266800;","Downstream effect of Hengduan Mountains on East China in the REMO regional climate model",2019,"10.1007/s00704-018-2721-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058481744&doi=10.1007%2fs00704-018-2721-0&partnerID=40&md5=0a2119116117bad2c8faa0768904e94c","The Hengduan Mountains and Tibetan Plateau possess unique topographical characteristics that serve as an effective blocking of the movement of the westerly wind in the middle and lower troposphere towards East China. This study examines results from a regional climate model (REMO) at the resolutions of 25 and 50 km for the period 1980–2012. The model is run using lateral boundary conditions from ERA-Interim (European Centre for Medium-Range Weather Forecasts interim reanalysis). There are only a few differences between 25 and 50 km in land surface/vegetation characteristics, but the major differences in this region are due to the orography. Results show that the high-resolution simulation performance is poor in winter, when southwesterly wind prevails, whereas it performs well in summer, when the westerly wind is substantially weakened in southern China. In comparison to the ERA-Interim wind field, the high-resolution simulation overestimates the air flow over the Hengduan Mountains near the ground surface, which influences the transport of atmospheric water vapor in the downstream region, i.e., over southern China. Specifically, with the help of the overestimated southwesterly wind, the amount of atmospheric water vapor transported increases considerably perennially by up to 20% in southern China, while it decreases remarkably by more than 5% throughout the year in a large area of Central and North China. These features lead to excessive precipitation and underestimated cloud cover in southern China, which probably causes the overestimated 2-m temperature in southern China. Our study emphasizes that, in such high-resolution-model studies for East Asia, special attention should be paid to the near-surface winds over the Hengduan Mountains. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature." "23975806200;57193848954;57195032810;57195032515;55339562000;25925845500;36109825000;57201483033;57201484008;57195031465;57195037869;57201480769;","Meteorological conditions during a severe, prolonged regional heavy air pollution episode in eastern China from December 2016 to January 2017",2019,"10.1007/s00704-018-2426-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045056863&doi=10.1007%2fs00704-018-2426-4&partnerID=40&md5=29d77f706f69b88770b11a9ae34a2026","A severe, prolonged and harmful regional heavy air pollution episode occurred in eastern China from December 2016 to January 2017. In this paper, the pollutant characteristics and the meteorological formation mechanism of this pollution event, including climate anomalies, surface weather conditions, planetary boundary layer structure and large-scale circulation features, were analysed based on observational pollution data, surface meteorological data, sounding data and ERA-Interim reanalysis data. The results are as follows. (1) Five pollution stages were identified in eastern China. The two most severe episodes occurred from December 27, 2016 to January 4, 2017 and from January 8 to 12 2017. During these two pollution episodes, fine mode particles were major contributors, and hourly PM2.5 concentrations often exceeded 150 μg/m3, reaching a maximum of 333 μg/m3 at Fuyang station. Gaseous pollutants were transformed into secondary aerosols through heterogeneous reactions on the surface of PM2.5. (2) Compared with the same period over the years 2000–2016, 2017 presented meteorological field climate anomalies in conjunction with unfavourable surface conditions (weak winds, high relative humidity, fewer hours of sunshine, high cloud cover) and adverse atmospheric circulation (weak East Asian winter monsoon and an abnormal geopotential height of 500 hPa), which caused poorer visibility in 2017 than in the other analysed years. (3) During the development of heavy pollution event, unfavourable surface weather conditions, including poorer visibility, weaker pressure, higher relative humidity, lower wind speed with unfavourable wind direction and less precipitation suppressed the horizontal diffusion ability of air pollutants. Furthermore, the unfavourable structure of the atmospheric boundary layer was the key cause of the rapid PM2.5 increase. The deep, strong temperature inversion layer and weak vertical wind velocity could have suppressed vertical motion and enhanced the stability of the near-surface atmosphere, causing the air pollutants to accumulate at low levels and exacerbating the air pollution problem. Finally, a persistent stagnant weather system with a weak geopotential height field of 1000 hPa and warm air advection at 850 hPa was the main feature of atmospheric circulation associated with the heavy pollution. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature." "55446881000;55490109900;57196238829;57200697528;57200697860;57200694284;","Performance of near real-time Global Satellite Mapping of Precipitation estimates during heavy precipitation events over northern China",2019,"10.1007/s00704-018-2391-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042225989&doi=10.1007%2fs00704-018-2391-y&partnerID=40&md5=3d6bbeac7d87fa106916e2031134c5c4","This study assesses the performance of near real-time Global Satellite Mapping of Precipitation (GSMaP_NRT) estimates over northern China, including Beijing and its adjacent regions, during three heavy precipitation events from 21 July 2012 to 2 August 2012. Two additional near real-time satellite-based products, the Climate Prediction Center morphing method (CMORPH) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS), were used for parallel comparison with GSMaP_NRT. Gridded gauge observations were used as reference for a performance evaluation with respect to spatiotemporal variability, probability distribution of precipitation rate and volume, and contingency scores. Overall, GSMaP_NRT generally captures the spatiotemporal variability of precipitation and shows promising potential in near real-time mapping applications. GSMaP_NRT misplaced storm centers in all three storms. GSMaP_NRT demonstrated higher skill scores in the first high-impact storm event on 21 July 2015. GSMaP_NRT passive microwave only precipitation can generally capture the pattern of heavy precipitation distributions over flat areas but failed to capture the intensive rain belt over complicated mountainous terrain. The results of this study can be useful to both algorithm developers and the scientific end users, providing a better understanding of strengths and weaknesses to hydrologists using satellite precipitation products. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature." "57204909571;56531065100;57204914178;57204922269;57204922303;57204910381;6603653680;","How to cool hot-humid (Asian) cities with urban trees? An optimal landscape size perspective",2019,"10.1016/j.agrformet.2018.11.027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057875005&doi=10.1016%2fj.agrformet.2018.11.027&partnerID=40&md5=c60a8961381f33e79cc5805b008dffad","Urban areas typically experience higher temperatures compared to surrounding rural areas that is known as the urban heat island effect (UHI). Urban greenery is capable of mitigating the UHI by creating microclimates that are lower in temperature than their surroundings, which are known as urban cooling islands (UCI). Previous studies have proved the effectiveness of UCI from different perspectives. However, a specific optimal level of landscape patch size at a regional scale that can be implemented by urban planners has not been identified. In this study, we estimated the optimal patch size in seven selected hot-humid Asian cities with the help of Google Cloud Computing, Python Programming, as well as spatial and statistical analysis. A two-tier (two optimal patch sizes) distribution of the threshold value of efficiency (TVoE) of urban trees in this region was found. Eight landscape-level indexes were used to explore the variance of TVoE. The percentage of landscape (PLAND), edge density (ED), mean landscape shape index (Shape_MN), mean fractal dimension (FRAC_MN), largest patch index (LPI), and mean Euclidian nearest-neighbor distance (ENN_MN) were found to have no significant correlation with TVoE. While the average normalized difference vegetation index (NDVI_MN) and average background temperature (BGT_MN) were found to be highly associated with the variance in TVoE. Further, a concept model that can simulate the effects of NDVI_MN and BGT_MN was also proposed. These findings extend the understanding of the UCI effect of urban trees as well as providing a basis for scientific climate adaption planning in this region. © 2018 Elsevier B.V." "55705928900;57206195507;56937445200;57014496500;12798705500;","A multi-dimensional hydro-climatic similarity and classification framework based on Budyko theory for continental-scale applications in China",2019,"10.3390/w11020319","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061606803&doi=10.3390%2fw11020319&partnerID=40&md5=7036f4dc35ecec383566857f242f9515","Our knowledge of the similarities and differences in ecological systems is vital to understanding the co-evolution of ecological factors. This study proposes a multi-dimensional hydro-climatic similarity and classification framework based on Budyko theory. The framework employs the dryness index (DI), evaporative index (EI), and an empirical parameter (ω) to further sub-divide four climatic zones (humid, semi-humid, semi-arid, and arid zones) in terms of DI. A criterion that define the similarities between stations is proposed to verify the classification to obtain optimal results. This method is applied to Mainland China, and 637 stations are adopted for continental-scale classification experiments. The point cloud of the Budyko curve for all the stations in Mainland China is plotted. We find that the hydrothermal conditions of the vertically distributed stations on the Budyko curve can be quite different in the same climatic zone when DI < 4.0. The higher the vertical locations of the stations on the Budyko curve are, the drier and colder the climates and corresponding natural landscapes. Under the proposed hydro-climatic classification framework, the four climatic zones are further divided into 17 sub-regions, and the hydrothermal conditions for each sub-region are discussed. The results suggest that regional differences of long-term water balance are resulted by not only mean annual hydrothermal factors and catchment forms but also annual distribution of hydrothermal factors. Our framework can provide hydrologically-based classification across continental scale and, thus, provide a profound understanding of hydrothermal conditions of continental-scale hydrological cycles. © 2019 by the authors." "36193302500;6603882177;56013882400;","The influence of climate on the masting behavior of Mexican beech: growth rings and xylem anatomy",2019,"10.1007/s00468-018-1755-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053404049&doi=10.1007%2fs00468-018-1755-3&partnerID=40&md5=7de30d938434e46f7e618e5f1de6cdf7","Key message: The Mexican beech undergoes masting events, on average, every 5.5 years. These events depend directly on precipitation. Abstract: Climate change has considerably impacted the protective functions of tropical montane cloud forests, possibly influencing the synchronicity of phenological processes and the distribution and physiology of plants. In particular, climatic fluctuations cause changes in the distribution of tree species. Mexican beech (Fagus grandifolia subsp. mexicana) is considered an endangered species, due to its restricted distribution and its being a Miocene relict, limited to tropical montane cloud forests in the mountains of the Sierra Madre Oriental in eastern Mexico. We analyzed the influence of temperature and precipitation in prompting changes to tree-ring width, as well as vessel frequency and diameter, of Mexican beech in eastern Mexico. We used growth rings and xylem vessels traits to infer the historical masting events of Mexican beech over the last 128 years. We obtained independent chronologies for Mexican beech in each of the studied sites, dating back 152–178 years. Precipitation was strongly associated with differences in tree-ring width between masting and non-masting years. Our study highlights the use of dendroecological research to detect climate-induced modifications in the vessel frequency and diameter of tree species inhabiting tropical montane cloud forests. This association also explained differences in vessel frequency and diameter recorded before, during, and after masting events. Our results revealed that Mexican beech undergoes masting events every 5.5 years on average, and that these events directly depend on minimum annual precipitation. In conclusion, our results advance our understanding on the plasticity of growth rings and vessels traits (frequency and diameter) in response to fluctuation in precipitation. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "23967739600;36469994200;7404358451;6506756436;57210010133;7004279605;6603490158;8255473900;","FVM 1.0: A nonhydrostatic finite-volume dynamical core for the IFS",2019,"10.5194/gmd-12-651-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061628953&doi=10.5194%2fgmd-12-651-2019&partnerID=40&md5=c4edfe4adf9f7919c355583b64c19746","We present a nonhydrostatic finite-volume global atmospheric model formulation for numerical weather prediction with the Integrated Forecasting System (IFS) at ECMWF and compare it to the established operational spectral-transform formulation. The novel Finite-Volume Module of the IFS (henceforth IFS-FVM) integrates the fully compressible equations using semi-implicit time stepping and non-oscillatory forward-in-time (NFT) Eulerian advection, whereas the spectral-transform IFS solves the hydrostatic primitive equations (optionally the fully compressible equations) using a semi-implicit semi-Lagrangian scheme. The IFS-FVM complements the spectral-transform counterpart by means of the finite-volume discretization with a local low-volume communication footprint, fully conservative and monotone advective transport, all-scale deep-atmosphere fully compressible equations in a generalized height-based vertical coordinate, and flexible horizontal meshes. Nevertheless, both the finite-volume and spectral-transform formulations can share the same quasi-uniform horizontal grid with co-located arrangement of variables, geospherical longitude-latitude coordinates, and physics parameterizations, thereby facilitating their comparison, coexistence, and combination in the IFS.
We highlight the advanced semi-implicit NFT finite-volume integration of the fully compressible equations of IFS-FVM considering comprehensive moist-precipitating dynamics with coupling to the IFS cloud parameterization by means of a generic interface. These developments - including a new horizontal-vertical split NFT MPDATA advective transport scheme, variable time stepping, effective preconditioning of the elliptic Helmholtz solver in the semi-implicit scheme, and a computationally efficient implementation of the median-dual finite-volume approach - provide a basis for the efficacy of IFS-FVM and its application in global numerical weather prediction. Here, numerical experiments focus on relevant dry and moist-precipitating baroclinic instability at various resolutions. We show that the presented semi-implicit NFT finite-volume integration scheme on co-located meshes of IFS-FVM can provide highly competitive solution quality and computational performance to the proven semi-implicit semi-Lagrangian integration scheme of the spectral-transform IFS. © Author(s) 2019." "6506286986;6602999057;56522444900;","The role of low-level clouds in the West African monsoon system",2019,"10.5194/acp-19-1623-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061300368&doi=10.5194%2facp-19-1623-2019&partnerID=40&md5=76743b16332b8817d7eddcbe09dec4f4","Realistically simulating the West African monsoon system still poses a substantial challenge to state-of-the-art weather and climate models. One particular issue is the representation of the extensive and persistent low-level clouds over southern West Africa (SWA) during boreal summer. These clouds are important in regulating the amount of solar radiation reaching the surface, but their role in the local energy balance and the overall monsoon system has never been assessed. Based on sensitivity experiments using the ICON model for July 2006, we show for the first time that rainfall over SWA depends logarithmically on the optical thickness of low clouds, as these control the diurnal evolution of the planetary boundary layer, vertical stability and finally convection. In our experiments, the increased precipitation over SWA has a small direct effect on the downstream Sahel, as higher temperatures due to increased surface radiation are accompanied by decreases in low-level moisture due to changes in advection, leading to almost unchanged equivalent potential temperatures in the Sahel. A systematic comparison of simulations with and without convective parameterization reveals agreement in the direction of the precipitation signal but larger sensitivity for explicit convection. For parameterized convection the main rainband is too far south and the diurnal cycle shows signs of unrealistic vertical mixing, leading to a positive feedback on low clouds. The results demonstrate that relatively minor errors, variations or trends in low-level cloudiness over SWA can have substantial impacts on precipitation. Similarly, they suggest that the dimming likely associated with an increase in anthropogenic emissions in the future would lead to a decrease in summer rainfall in the densely populated Guinea coastal area. Future work should investigate longer-term effects of the misrepresentation of low clouds in climate models, e.g. moderated through effects on rainfall, soil moisture and evaporation. © 2019 Author(s)." "55758458400;57191034805;55705948900;57188699861;57205267078;57205726330;57204504742;7202041928;14019100300;","Influence of cloud microphysical processes on black carbon wet removal, global distributions, and radiative forcing",2019,"10.5194/acp-19-1587-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061336576&doi=10.5194%2facp-19-1587-2019&partnerID=40&md5=8ea860a53cb3868f894f889619de14d8","Parameterizations that impact wet removal of black carbon (BC) remain uncertain in global climate models. In this study, we enhance the default wet deposition scheme for BC in the Community Earth System Model (CESM) to (a) add relevant physical processes that were not resolved in the default model and (b) facilitate understanding of the relative importance of various cloud processes on BC distributions. We find that the enhanced scheme greatly improves model performance against HIPPO observations relative to the default scheme. We find that convection scavenging, aerosol activation, ice nucleation, evaporation of rain or snow, and below-cloud scavenging dominate wet deposition of BC. BC conversion rates for processes related to in-cloud water-ice conversion (i.e., riming, the Bergeron process, and evaporation of cloud water sedimentation) are relatively smaller, but have large seasonal variations. We also conduct sensitivity simulations that turn off each cloud process one at a time to quantify the influence of cloud processes on BC distributions and radiative forcing. Convective scavenging is found to have the largest impact on BC concentrations at mid-altitudes over the tropics and even globally. In addition, BC is sensitive to all cloud processes over the Northern Hemisphere at high latitudes. As for BC vertical distributions, convective scavenging greatly influences BC fractions at different altitudes. Suppressing BC droplet activation in clouds mainly decreases the fraction of column BC below 5 km, whereas suppressing BC ice nucleation increases that above 10 km. During wintertime, the Bergeron process also significantly increases BC concentrations at lower altitudes over the Arctic. Our simulation yields a global BC burden of 85 Gg; corresponding direct radiative forcing (DRF) of BC estimated using the Parallel Offline Radiative Transfer (PORT) is 0.13 W m -2 , much lower than previous studies. The range of DRF derived from sensitivity simulations is large, 0.09-0.33 W m -2 , corresponding to BC burdens varying from 73 to 151 Gg. Due to differences in BC vertical distributions among each sensitivity simulation, fractional changes in DRF (relative to the baseline simulation) are always higher than fractional changes in BC burdens; this occurs because relocating BC in the vertical influences the radiative forcing per BC mass. Our results highlight the influences of cloud microphysical processes on BC concentrations and radiative forcing. © 2019 Author(s)." "36107698500;57202477448;","Observations on changes in Korean Changma rain associated with climate warming in 2017 and 2018",2019,"10.1007/s11869-018-00658-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060027455&doi=10.1007%2fs11869-018-00658-5&partnerID=40&md5=1f74a91b42047b5a556457b8c983403d","The period of prolonged summer rain in Korea called Changma was studied. Changma, also known as Meiyu in China and Baiu in Japan, is an integral part of the East Asian Summer Monsoon System. Until the 1980s, the Changma rainy season in Korea occurred from late June and July for 30 to 40 days or approximately 4 to 5 weeks. This study investigated whether changes have been observed in the timing and amounts of precipitation associated with Changma. From the analysis of meteorological data obtained in 2017 and 2018, it is observed that the length of the rainy season has shortened to 2 to 3 weeks in agreement with the earlier studies. Furthermore, during the rainy season, there were many days of no rain and partly cloudy days. Although an active elongated-linear Changma front was common in the past, it was found that an inactive Changma front with a large meridional amplitude has caused intermittent rain showers for several hours from linear convective cloud streaks. In recent years, this has produced large variations in rainfall amounts among regional measuring stations in Korea. Climate warming in the north side of the Changma front has resulted in less contrast with the warm-moist air in the south side of it from the Pacific Ocean. This has resulted in a weaker and inactive quasi-stationary front which has caused a discontinuous broken Changma front and sporadic showery days. It is also observed that maritime polar air mass, mP, over the Okhotsk Sea of far eastern Russia has not affected the Changma front over the Korean Peninsula. Overall, this study found that the characteristics of past Changma fronts have changed significantly in recent years. The present observations imply the need of further studies on climate change and summer rainfall including water management. © 2019, Springer Media B.V., onderdeel van Springer Nature." "55268661300;55461837700;35509639400;57205562988;","Thermodynamic control on the poleward shift of the extratropical jet in climate change simulations: The role of rising high clouds and their radiative effects",2019,"10.1175/JCLI-D-18-0417.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060553113&doi=10.1175%2fJCLI-D-18-0417.1&partnerID=40&md5=2fd382b1a57d974cb631b4c99b9697c1","Extratropical eddy-driven jets are predicted to shift poleward in a warmer climate. Recent studies have suggested that cloud radiative effects (CRE) may enhance the amplitude of such shifts. But there is still considerable uncertainty about the underlying mechanisms, whereby CRE govern the jet response to climate change. This study provides new insights into the role of CRE in the jet response to climate change by exploiting the output from six global warming simulations run with and without atmospheric CRE (ACRE). Consistent with previous studies, it is found that the magnitude of the jet shift under climate change is substantially increased in simulations run with ACRE. It is hypothesized that ACRE enhance the jet response to climate change by increasing the upper-tropospheric baroclinicity due to the radiative effects of rising high clouds. The lifting of the tropopause and high clouds in response to surface warming arises from the thermodynamic constraints placed on water vapor concentrations. Hence, the influence of ACRE on the jet shift in climate change simulations may be viewed as an additional ""robust"" thermodynamic constraint placed on climate change by the Clausius-Clapeyron relation. The hypothesis is tested in simulations run with an idealized dry GCM, in which the model is perturbed with a thermal forcing that resembles the ACRE response to surface warming. It is demonstrated that 1) the enhanced jet shifts found in climate change simulations run with ACRE are consistent with the atmospheric response to the radiative warming associated with rising high clouds, and 2) the amplitude of the jet shift scales linearly with the amplitude of the ACRE forcing. © 2019 American Meteorological Society." "57195398231;56892889800;7501757094;","Aerosol direct radiative and cloud adjustment effects on surface climate over eastern China: Analyses of WRF model simulations",2019,"10.1175/JCLI-D-18-0236.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061009604&doi=10.1175%2fJCLI-D-18-0236.1&partnerID=40&md5=edbca167f2b1bef440030222e94ce281","The WRF-simulated changes in clouds and climate due to the increased anthropogenic aerosols for the summers of 2002-08 (vs the 1970s) over eastern China were used to offline calculate the radiative forcings associated with aerosol-radiation (AR) and aerosol-cloud-radiation (ACR) interactions, which subsequently facilitated the interpretation of surface temperature changes. During this period, the increases of aerosol optical depth (ΔAOD) averaged over eastern China range from 0.18 in 2004 to 0.26 in 2007 as compared to corresponding cases in the 1970s, and the multiyear means (standard deviations) of AR and ACRforcings at the surface are-6.7 (0.58) and-3.5 (0.63)Wm -2 , respectively, indicating the importance of cloud changes in affecting both the aerosol climate forcing and its interannual variation. The simulated mean surface cooling is 0.35°C, dominated by AR and ACR with a positive (cooling) feedback associated with changes in meteorology (~10%), and two negative (warming) feedbacks associated with decreases in latent (~70%) and sensible (~20%) heat fluxes. More detailed spatial characteristics were analyzed using ensemble simulations for the year 2008. Three regions-Jing-Jin-Ji (ΔAOD;0.63), Sichuan basin (ΔAOD;0.31), and middle Yangtze River valley (ΔAOD ~ 0.26)-at different climate regimes were selected to investigate the relative roles of AR and ACR. While the AR forcing is closely related to ΔAOD values, the ACR forcing presents different regional characteristics owing to cloud changes. In addition, the surface heat flux feedbacks are also different between regions. The study thus illustrates that ACR forcing is useful as a diagnostic parameter to unravel the complexity of climate change to aerosol forcing over eastern China. © 2019 American Meteorological Society." "15047538100;15050523700;6602135370;36242447900;57203816066;","Simulation of extreme Indian summer monsoon years in Coupled Model Intercomparison Project Phase 5 models: Role of cloud processes",2019,"10.1002/joc.5851","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053049500&doi=10.1002%2fjoc.5851&partnerID=40&md5=35dfe5ff54cb5f2948de26bf05f72e7e","The Indian summer monsoon (ISM) is a climate coupled system where cloud processes play a significant role in modulating the thermodynamics and dynamics of the atmosphere. The realistic representation of cloud by coupled model becomes indispensable for the simulation of the rainfall variability dictating the extreme ISM rainfall years. This study pinpoints the importance of correct representation of cloud processes and different types of rainfall in coupled climate model for the realistic simulation of monsoon extreme rainfall years. The study has used historical runs of Coupled Model Intercomparison Project Phase 5 (CMIP5) models. It provided best opportunity to investigate the ISM rainfall characteristics in case of anomalous monsoon and associated physical processes responsible for the modulation of large-scale circulation. The study has identified the mechanism behind the better simulation of anomalous years. Relatively more cloud condensate at upper level and middle level is present in excess monsoon years. Pertaining to phase changes and thermodynamical processes, there will be relatively more tropospheric temperature gradient and it will be conducive for strong monsoon. Proper representation of convective and stratiform rain is seen during extreme years. Precipitable water is also relatively more during excess monsoon years. As a result, total rainfall also enhances and it leads to excess monsoon. In contrast, during deficient monsoon relatively less cloud condensate at upper level and middle level is present. Therefore, the correct representation of cloud condensate vertical profile and stratiform/convective rain are crucial for the better simulation of excess and deficient monsoon, which may further improve the variability of ISM in climate model. This study connotes the urgent need of the improvement of cloud parameterization in coupled climate models for the betterment of monsoon variability and realistic representation of deficient/excess monsoon rainfall patterns over Indian subcontinent. © 2018 Royal Meteorological Society" "55717244800;57206183419;57208660400;57206200324;","Impact of Integrated Vertical Overlap of Cumulus and Stratus on the Global Precipitation and Radiation Processes in the Seoul National University Atmosphere Model Version 0 With a Unified Convection Scheme (SAM0-UNICON)",2019,"10.1029/2018MS001570","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061618923&doi=10.1029%2f2018MS001570&partnerID=40&md5=75d5b929878c6b8a2caefe9d335527ce","The previously proposed parameterization for the integrated vertical overlap of cumulus and stratus is implemented online into the cloud microphysics and radiation schemes of the Seoul National University Atmosphere Model version 0 with a Unified Convection Scheme (SAM0-UNICON). Instead of a single-merged cloud, the modified radiation scheme handles cumulus, stratus, and stratiform snow, separately, with each type having its own optical properties and vertical overlap structures. The integrated cloud overlap parameterization implemented into the cloud microphysics schemes do not reduce the biases of surface precipitation rate (PRECT) and cloud radiative forcing. Although it changes the overlap structures of clouds and precipitation areas, as well as the associated cloud microphysical processes either directly or indirectly, strong cancelation occurs among these terms, resulting in small changes to the global-mean PRECT and cloud radiative forcing. The integrated cloud overlap parameterization implemented into the radiation scheme has a substantial impact on the simulated climate: the global-mean cloud radiative forcing decreases substantially, mainly due to the separate treatment of radiative properties of individual cumulus, stratus, and stratiform snow, and PRECT exhibits strong regional responses. Sensitivity simulations showed that vertical cloud overlap exerts a weaker influence on the global-mean PRECT than the previous off-line simulations, implying that the indirect effect offsets the direct effect. In contrast to the off-line simulations, the enhanced randomness of cumulus overlap increases PRECT over the western Pacific warm pool region. Our study indicates that vertical cloud overlap has substantial impacts on global climate through complex interactions with other physical processes. ©2019. The Authors." "57131609600;55913183200;7402989545;55899884100;36093295000;36648197400;25226875800;24382049500;","Climate Sensitivity and Feedbacks of a New Coupled Model CAMS-CSM to Idealized CO 2 Forcing: A Comparison with CMIP5 Models",2019,"10.1007/s13351-019-8074-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061185748&doi=10.1007%2fs13351-019-8074-5&partnerID=40&md5=9179b3b2adc57ffa49cb89ecdcf3b891","Climate sensitivity and feedbacks are basic and important metrics to a climate system. They determine how large surface air temperature will increase under CO 2 forcing ultimately, which is essential for carbon reduction policies to achieve a specific warming target. In this study, these metrics are analyzed in a climate system model newly developed by the Chinese Academy of Meteorological Sciences (CAMS-CSM) and compared with multi-model results from the Coupled Model Comparison Project phase 5 (CMIP5). Based on two idealized CO 2 forcing scenarios, i.e., abruptly quadrupled CO 2 and CO 2 increasing 1% per year, the equilibrium climate sensitivity (ECS) and transient climate response (TCR) in CAMS-CSM are estimated to be about 2.27 and 1.88 K, respectively. The ECS is near the lower bound of CMIP5 models whereas the TCR is closer to the multi-model ensemble mean (MME) of CMIP5 due to compensation of a relatively low ocean heat uptake (OHU) efficiency. The low ECS is caused by an unusually negative climate feedback in CAMS-CSM, which is attributed to cloud shortwave feedback (λ SWCL ) over the tropical Indo-Pacific Ocean. The CMIP5 ensemble shows that more negative λ SWCL is related to larger increase in low-level (925–700 hPa) cloud over the tropical Indo-Pacific under warming, which can explain about 90% of λ SWCL in CAMS-CSM. Static stability of planetary boundary layer in the pre-industrial simulation is a critical factor controlling the low-cloud response and λ SWCL across the CMIP5 models and CAMS-CSM. Evidently, weak stability in CAMS-CSM favors lowcloud formation under warming due to increased low-level convergence and relative humidity, with the help of enhanced evaporation from the warming tropical Pacific. Consequently, cloud liquid water increases, amplifying cloud albedo, and eventually contributing to the unusually negative λ SWCL and low ECS in CAMS-CSM. Moreover, the OHU may influence climate feedbacks and then the ECS by modulating regional sea surface temperature responses. © 2019, The Chinese Meteorological Society and Springer-Verlag GmbH Germany, part of Springer Nature." "57208163987;49662076300;16550482700;37034312700;6602635781;","Impacts of new particle formation on short-term meteorology and air quality as determined by the NPF-explicit WRF-chem in the midwestern United States",2019,"10.4209/aaqr.2018.05.0163","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064010332&doi=10.4209%2faaqr.2018.05.0163&partnerID=40&md5=bea09c60eeaefecf056de0e30db3c408","New particle formation (NPF) from nucleation and subsequent nuclei growth, which is frequently observed in the troposphere, is critical to aerosol-cloud interactions yet difficult to simulate. In this work, regional simulations with the fully coupled NPF-explicit WRF-Chem model link NPF to cloud properties and to changes in both meteorology and air quality in the U.S. Midwest during summer 2008. Simulations that include NPF have higher concentrations of condensation nuclei, as anticipated from the particle production associated with nucleation, leading to enhanced concentrations of cloud condensation nuclei (CCN) at high supersaturations. However, the online-coupled model develops a number of unexpected features that can be traced to a feedback loop involving aqueous (in-cloud) oxidation of sulfur combined with boundary layer NPF. Simulations with NPF (relative to simulations without) exhibit reduced PM2.5 sulfate mass, cloud dimming (reductions in the cloud frequency, CCN concentration at a low supersaturation, cloud optical depth, and cloud droplet number concentration), and enhanced surface-reaching shortwave radiation. This effect of NPF on the PM2.5 mass is mostly absent for other constituents of PM2.5. The implications of this feedback loop, which is not considered in most climate and air quality modeling, are discussed. © Taiwan Association for Aerosol Research." "56377384400;6507224579;","The Atmospheric Circulation and Climate of Terrestrial Planets Orbiting Sun-like and M Dwarf Stars over a Broad Range of Planetary Parameters",2019,"10.3847/1538-4357/aafb33","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062009136&doi=10.3847%2f1538-4357%2faafb33&partnerID=40&md5=d7acd3f2cbdfee9f2e80cb4ec613fe85","The recent detections of temperate terrestrial planets orbiting nearby stars and the promise of characterizing their atmospheres motivate a need to understand how the diversity of possible planetary parameters affects the climate of terrestrial planets. In this work, we investigate the atmospheric circulation and climate of terrestrial exoplanets orbiting both Sun-like and M dwarf stars over a wide swath of possible planetary parameters, including the planetary rotation period, surface pressure, incident stellar flux, surface gravity, planetary radius, and cloud particle size. We do so using a general circulation model (GCM) that includes nongray radiative transfer and the effects of clouds. The results from this suite of simulations generally show qualitatively similar dependencies of circulation and climate on planetary parameters to idealized GCMs, with quantitative differences due to the inclusion of additional model physics. Notably, we find that the effective cloud particle size is a key unknown parameter that can greatly affect the climate of terrestrial exoplanets. We confirm a transition between low and high dayside cloud coverage of synchronously rotating terrestrial planets with increasing rotation period. We determine that this cloud transition is due to eddy-driven convergence near the substellar point and should not be parameterization dependent. Finally, we compute full-phase light curves from our simulations of planets orbiting M dwarf stars, finding that changing incident stellar flux and rotation period affect observable properties of terrestrial exoplanets. Our GCM results can guide expectations for planetary climate over the broad range of possible terrestrial exoplanets that will be observed with future space telescopes. © 2019. The American Astronomical Society. All rights reserved." "57188848315;35098748100;7403564495;35099345700;56095856700;55576700800;57203228273;57214924430;56770031000;57196548688;57190214513;","Spatiotemporal Distributions of Cloud Parameters and the Temperature Response Over the Mongolian Plateau During 2006-2015 Based on MODIS Data",2019,"10.1109/JSTARS.2018.2857827","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050993218&doi=10.1109%2fJSTARS.2018.2857827&partnerID=40&md5=c5a975359828b8ef4c1704ff1d9940a3","The Mongolian Plateau (MP) has important influences on regional and global climate change. The spatiotemporal variations in the cloud cover and cloud optical thickness of total, high, middle, and low clouds over the MP during the daytime from 2006 to 2015 are analyzed using MODIS level 2 atmospheric data. Results show that the annual average total cloud cover over the MP decreases from the forest area in the northeast to the desert area in the southwest. The total cloud cover over the MP is obviously higher in summer than in other seasons, in which high clouds have a largest proportion, with the substantial total cloud cover changes. The spatial distributions of the high, middle, and low cloud covers over the MP are highly variable. The cooling effect of the cloud net radiative forcing is greater during the daytime in summer than in other seasons, which is likely associated with thick cloud optical thickness or large cloud cover in summer. Combined with the analyses of relationships among cloud cover, cloud optical thickness, cloud radiative forcing, and air temperature, the results show that significantly negative correlations exist between cloud optical thickness and cloud radiative forcing, and between total cloud cover and air temperature in the MP. The decrease in air temperature in summer over the MP during daytime confirm that the increase in the daytime total cloud cover strengthen the cooling effects of clouds and decrease the air temperature, especially in the high-value area with cloud cover distribution over the northeast MP. © 2018 IEEE." "57203453922;7203047936;","Development of a new algorithm to identify clear sky MSU data using AMSU-a data for verification",2019,"10.1109/TGRS.2018.2859744","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051806733&doi=10.1109%2fTGRS.2018.2859744&partnerID=40&md5=98f1c4cdd592630b31e9db9bdeffe1a8","Observations from the microwave sounding unit (MSU), from 1978 to 2006 and its successor, the Advanced Microwave Sounding Unit-A (AMSU-A, 1998-present), and onboard the National Oceanic and Atmospheric Administration's polar-orbiting satellites have been widely used for estimating global climate trends. The MSU has a long-term data set, but it is difficult to obtain cloud information like the cloud liquid water path (LWP) directly from this data set. To monitor and investigate the cloud effect on global upper air temperature trends using MSU observations, a cloud detection algorithm must be developed for the MSU. Considering the similar center frequencies of MSU channel 1 and AMSU-A channel 3, a new cloud detection algorithm is established based on the differences between observed and model-simulated brightness temperatures (O-B-μ (α)-μ(φ)) of MSU channel 1 or AMSU-A channel 3 over oceans, where μ (φ) is a latitudinal dependent global mean bias and μ (α) is the global mean bias depending on scan angle. If a data point satisfies the condition of O-B-μ (α)-μ (φ) ≥ 1 K, it is removed from the clear sky data set. In order to ensure that those points that are partially affected by the clouds, such as clear and cloud mixed fields-of-views located near cloud edges and/or within optically thin clouds, all data points within the 60-km radial distance of the detected point are removed. Validated with the AMSU-A derived LWP retrievals, about 50% of the clear sky data are successively identified and 99% of the cloudy radiances are successively removed for all NOAA-15 AMSU-A data on January 15, April 15, July 15, and October 15, 2002. © 2018 IEEE." "56241347800;7102949705;","Influence of land use and land cover change on the formation of local lightning",2019,"10.3390/rs11040407","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062555684&doi=10.3390%2frs11040407&partnerID=40&md5=94ec0064c6d570e25657bbd07f52816a","Land use and land cover (LULC) play a crucial role in the interaction between the land and atmosphere, influencing climate at local, regional, and global scales. LULC change due to urbanization has significant impacts on local weather and climate. Land-cover changes associated with urbanization create higher air temperatures compared to the surrounding rural area, known as the ""urban heat island (UHI)"" effect. Urban landscapes also affect formation of convective storms. In recent years, the effect of urbanization on local convections and lightning has been studied very extensively. In this paper a long-term study has been carried out taking cloud-to-ground (CG) lightning data (1998-2012) from Tai-Power Company, and particulate matter (PM10), sulfur dioxide (SO2) data (2003-2012) from the Environmental Protection Administration (EPA) of Taiwan, in order to investigate the influence of LULC change through urbanization on CG lightning activity over Taipei taking into account in situ data of population growth, land use change and mean surface temperature (1965-2010). The thermal band of the Land-Sat 7 satellite was used to generate the apparent surface temperature of New Taipei City. It was observed that an enhancement of 60-70% in the flash density over the urban areas compared to their surroundings. The spatial distribution of the CG lightning flashes follows closely the shape of the Taipei city heat island, thereby supporting the thermal hypothesis. The PM10 and SO2 concentrations showed a positive linear correlation with the number of cloud-to-ground flashes, supporting the aerosol hypothesis. These results indicate that both hypotheses should be considered to explain the CG lightning enhancements over the urban areas. The results obtained are significant and interesting and have been explained from the thermodynamic point of view. © 2019 by the authors." "57193458437;55900043700;57203642166;","Developing Daily Cloud-Free Snow Composite Products From MODIS and IMS for the Tienshan Mountains",2019,"10.1029/2018EA000460","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061983836&doi=10.1029%2f2018EA000460&partnerID=40&md5=c470b78c3bdad592381abc3bda062110","Daily cloud-free snow cover products are important premise and foundation for hydrological simulation, climate system research, and snow disaster monitoring in the Tienshan Mountains, Central Asia. In this study, partial clouds appearing in the Moderate Resolution Imaging Spectroradiometer (MODIS) were removed by temporal and spatial filtering, and the remaining cloud pixels were replaced by Interactive Multisensor Snow and Ice Mapping System (IMS). The results show that the retrieved annual mean snow cover obtained from the improved MODIS product data is 31.5% higher than the original MODIS product. Through validation performed via in situ observations, the overall accuracy, land accuracy, and snow accuracy also increased to 88.2%, 91.9%, and 81.9%, respectively. However, the overall accuracy shows a lower accuracy in transitional months compared to other months, which derives mainly from the difference in spatial scales between IMS and in situ observations. ©2019. The Authors." "55473260200;36626757400;57203398578;55364203100;56102252600;57205170188;","An effective similar-pixel reconstruction of the high-frequency cloud-covered areas of Southwest China",2019,"10.3390/rs11030336","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061362635&doi=10.3390%2frs11030336&partnerID=40&md5=8194e33cdf3efd38fdf9ff642ea804bf","With advantages of multispatial resolutions, a high retrieval accuracy, and a high temporal resolution, the satellite-derived land surface temperature (LST) products are very important LST sources. However, the greatest barrier to their wide application is the invalid values produced by large quantities of cloudy pixels, especially for regions frequently swathed in clouds. In this study, an effective method based on the land energy balance theory and similar pixels (SP) method was developed to reconstruct the LSTs over cloudy pixels for the widely used MODIS LST (MOD11A1). The southwest region of China was selected as the study area, where extreme drought has frequently occurred in recent years in the context of global climate change and which commonly exhibits cloudy and foggy weather. The validation results compared with in situ LSTs showed that the reconstructed LSTs have an average error < 1.00 K (0.57 K at night and -0.14 K during the day) and an RMSE < 3.20 K (1.90 K at night and 3.16 K in the daytime). The experiment testing the SP interpolation indicated that the spatial structure of the LST has a greater effect on the SP performance than the size of the data-missing area, which benefits the LST reconstruction in the area frequently covered by large clouds. © 2019 by the authors." "57190730481;57195612511;13409246100;57214924430;57200330330;57200336896;57200331518;","Spatial and temporal variability in extreme temperature and precipitation events in Inner Mongolia (China) during 1960–2017",2019,"10.1016/j.scitotenv.2018.08.262","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052448093&doi=10.1016%2fj.scitotenv.2018.08.262&partnerID=40&md5=4fd736899330aff5e7a9fc8edd5f30e2","Due to global warming, extreme climate events have become an important issue, and different geographical regions have different sensitivities to climate change. Therefore, temporal and spatial variations in extreme temperature and precipitation events in Inner Mongolia were analyzed based on the daily maximum temperature, minimum temperature, and precipitation data during the period of 1960–2017. The results showed that warm extreme indices, such as SU25, TX90p, TN90p, and WSDI, significantly increased, whereas the cold extreme indices, such as FD0, TX10p, TN10p, and CSDI, significantly decreased; all indices have obvious abrupt changes based on the Mann-Kendall test; nighttime warming was higher than daytime warming. Extreme precipitation indices slightly decreased overall. All of the extreme temperature and precipitation indices had long-range correlations based on detrended fluctuation analysis (a > 0.5), thereby indicating that the extreme climate indices will maintain their current trend directions in the future. ENSO, AO, and IOD had a strong positive influence on warm extremes and a strong negative influence on cold extremes in Inner Mongolia. NCEP/NCAR and ERA-20CM reanalysis showed that strengthening anticyclone circulation, increasing geopotential height, decreasing daytime cloudiness and increasing nightime cloudiness contributed to changes in climate extremes in Inner Mongolia. © 2018 Elsevier B.V." "56230211700;36495301700;7005634455;7401776640;7006246996;","Meteorological drivers and large-scale climate forcing of West Antarctic surface melt",2019,"10.1175/JCLI-D-18-0233.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060530936&doi=10.1175%2fJCLI-D-18-0233.1&partnerID=40&md5=3d980fb1b4bd277e082ef50f3c4a7f90","Understanding the drivers of surface melting in West Antarctica is crucial for understanding future ice loss and global sea level rise. This study identifies atmospheric drivers of surface melt on West Antarctic ice shelves and ice sheet margins and relationships with tropical Pacific and high-latitude climate forcing using multidecadal reanalysis and satellite datasets. Physical drivers of ice melt are diagnosed by comparing satellite-observed melt patterns to anomalies of reanalysis near-surface air temperature, winds, and satellitederived cloud cover, radiative fluxes, and sea ice concentration based on an Antarctic summer synoptic climatology spanning 1979-2017. Summer warming in West Antarctica is favored by Amundsen Sea (AS) blocking activity and a negative phase of the southern annular mode (SAM), which both correlate with El Niño conditions in the tropical Pacific Ocean. Extensive melt events on the Ross-Amundsen sector of the West Antarctic Ice Sheet (WAIS) are linked to persistent, intense AS blocking anticyclones, which force intrusions of marine air over the ice sheet. Surface melting is primarily driven by enhanced downwelling longwave radiation from clouds and a warm, moist atmosphere and by turbulent mixing of sensible heat to the surface by föhn winds. Since the late 1990s, concurrent with ocean-driven WAIS mass loss, summer surface melt occurrence has increased from the Amundsen Sea Embayment to the eastern Ross Ice Shelf. We link this change to increasing anticyclonic advection of marine air into West Antarctica, amplified by increasing air-sea fluxes associated with declining sea ice concentration in the coastal Ross-Amundsen Seas. © 2019 American Meteorological Society." "57195252009;56523711200;7003528716;7004190791;","Weather at selected astronomical sites – An overview of five atmospheric parameters",2019,"10.1093/mnras/sty2982","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061093189&doi=10.1093%2fmnras%2fsty2982&partnerID=40&md5=20bc84168ebcd5afd0b0f27b5de26121","Weather has a critical impact on observations at optical and infrared wavelengths, and is a key factor in assessing the performance and productivity of future facilities. As a reference for comparison, we present an analysis of cloud cover, 200-hPa wind speed, precipitable water vapour, vertical wind velocity, and aerosol index, for 15 observatory sites around the world. Our study employs ERA-40 and Total Ozone Mapping Spectrometer climatological data covering a 45-yr time period. We have examined this data set for long-term trends. Several sites are found to show significant long-term changes in some parameters, possibly due to climate change. Four sites show significant increases in cloud cover (99 per cent confidence level). Four sites show changes in 200-hPa wind speed. Eight sites show increases or decreases in precipitable water vapour. The largest changes are found for Antarctic sites, which have clear trends of increasing cloud cover and water vapour. These results should help to characterize the relative astronomical potential of the sites and highlight the influence of both seasonal variations and long-term trends. © 2018 The Author(s)." "35098162000;54416697300;55154955700;11239265600;37058739000;56014853400;","Cloud mask-related differential linear adjustment model for MODIS infrared water vapor product",2019,"10.1016/j.rse.2018.12.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058195451&doi=10.1016%2fj.rse.2018.12.005&partnerID=40&md5=f92310121401464d29797447433c9a70","Water vapor is the primary greenhouse gas of the Earth-atmosphere system and plays a vital role in understanding climate change, if correctly measured from satellites. The Moderate Resolution Imaging Spectroradiometer (MODIS) can monitor water vapor retrievals at near-infrared (nIR) bands in the daytime as well as at infrared (IR) bands in both daytime and night time. However, the accuracy of IR retrievals under confident clear conditions (>99% probability) is much poorer than that of nIR retrievals. Additionally, IR retrievals under unconfident clear conditions (>95%, >66% and ≤66% probabilities) are usually discarded because the possible presence of clouds would further reduce their accuracy. In this study, we develop a cloud mask-related differential linear adjustment model (CDLAM) to adjust IR retrievals under all confident clear conditions. The CDLAM-adjusted IR retrievals are evaluated with the linear least square (LS) adjusted nIR retrievals under confident clear condition and Global Positioning System (GPS) observations under different probabilities of clear conditions. Both case studies in the USA and global (65° S~65° N) evaluation reveal that the CDLAM can significantly reduce uncertainties in IR retrievals at all clear-sky confidence levels. Moreover, the accuracy of the CDLAM-adjusted IR retrievals under unconfident clear conditions is much better than IR retrievals without adjustment under confident clear conditions, highlighting the effectiveness of the CDLAM in enhancing the accuracy of IR retrievals at all clear-sky confidence levels as well as the data availability improvement of IR retrievals after adjustment with the CDLAM (14% during the analyzed time periods). The most likely reason for the efficiency of the CDLAM may be that the deviation of the differential water vapor information derived by the differential process is significantly shrunken after the linear regression analysis in the presented model. Therefore, the CDLAM is a promising tool for effectively adjusting IR retrievals under all probabilities of clear conditions and can improve our knowledge of the water vapor distribution and variation. © 2018 Elsevier Inc." "35777991000;35509463200;10042470700;35301550500;8308107100;56012593900;16641272900;57207556152;16024614000;55639314000;7005165467;","Constraints to vegetation growth reduced by region-specific changes in seasonal climate",2019,"10.3390/cli7020027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062177942&doi=10.3390%2fcli7020027&partnerID=40&md5=66dd24c253fa0838b590bbcd2f323a34","We qualitatively and quantitatively assessed the factors related to vegetation growth using Earth system models and corroborated the results with historical climate observations. The Earth system models showed a systematic greening by the late 21st century, including increases of up to 100% in Gross Primary Production (GPP) and 60% in Leaf Area Index (LAI). A subset of models revealed that the radiative effects of CO 2 largely control changes in climate, but that the CO 2 fertilization effect dominates the greening. The ensemble of Earth system model experiments revealed that the feedback of surface temperature contributed to 17% of GPP increase in temperature-limited regions, and radiation increase accounted for a 7% increase of GPP in radiation-limited areas. These effects are corroborated by historical observations. For example, observations confirm that cloud cover has decreased over most land areas in the last three decades, consistent with a CO 2 -induced reduction in transpiration. Our results suggest that vegetation may thrive in the starkly different climate expected over the coming decades, but only if plants harvest the sort of hypothesized physiological benefits of higher CO 2 depicted by current Earth system models. © 2019 by the authors." "57201984518;56522444900;56522768500;6603442521;55806727200;","A new and flexible rainy season definition: Validation for the Greater Horn of Africa and application to rainfall trends",2019,"10.1002/joc.5856","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054495225&doi=10.1002%2fjoc.5856&partnerID=40&md5=4c586ffe024141eaf136c7055b51f7cd","Previous studies on observed or projected rainfall trends for the Greater Horn of Africa (GHA) generally focus on calendric 3-month periods, and thus partly neglect the complexity of rainfall seasonality in this topographically heterogeneous region. This study introduces a novel and flexible methodology to identify the rainfall seasonality, the onset, cessation and duration of the rainy seasons and the associated uncertainties from rainfall time series. The definition is applied to the Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) satellite product and an extensive rain gauge data set. A strong agreement with known seasonal dynamics in the region and the commonly used calendric rainy seasons is demonstrated. Compared to the latter definition, a clear added value is found for the new approach as it captures the local rainfall features (associated with, for example, the sea breeze), thus facilitating evaluations across rainfall seasonality borders. While previously known trends are qualitatively confirmed, trends are amplified in some regions using the flexible definition method. Notably, a drying trend in Tanzania and Democratic Republic of Congo and a wetting trend in central Sudan and parts of eastern Ethiopia and Kenya can be detected. The trends are regionally associated with changes in rainy season cessation. CHIRPS and station trend patterns are consistent over larger regions of the GHA, but differ in regions with known rainfall contributions from warmer cloud tops. Discrepancies are found in coastal and topographically complex areas, and regions with an unstable seasonality of rainfall. As expected, CHIRPS shows spatially more homogeneous trends compared to station data. The more precise definition of the rainy season facilitates the assessment of rainfall characteristics like intensity, rainfall amounts or temporal shifts of rainy seasons. This novel methodology could also provide a more adequate calibration of climate model simulations thus potentially enabling more realistic climate change projections for the GHA. © 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society." "55510628800;57191754390;56526794400;36994106300;","Simulation of interannual variability of summer rainfall over the Tibetan Plateau by the Weather Research and Forecasting model",2019,"10.1002/joc.5840","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052924484&doi=10.1002%2fjoc.5840&partnerID=40&md5=63ecc212c5757ed9f62043571b6ed494","A realistic simulation of rainfall over the Tibetan Plateau (TP) is a big challenge for both regional and global climate models. In this study, we investigate the simulations of summer rainfall over the TP from 1979 to 2010 by the Weather Research and Forecasting (WRF) model with various horizontal resolutions and cumulus schemes, with a focus on the difference in the model's skill in simulating interannual variability of rainfall between early and high summer. The WRF captures spatial pattern of climatological summer mean rainfall over the TP. However, it produces apparent wet bias, especially in southern and eastern edges of the TP. Despite this climatological bias, WRF skilfully reproduces the interannual variability of summer rainfall over the southeastern TP, where maximum rainfall is located. An increase in horizontal resolution or an appropriate cumulus scheme mostly improves the simulation of climatological mean rainfall. However, the phase of interannual variability of simulated rainfall is not sensitive to horizontal resolution and cumulus scheme. Instead, it is sensitive to mechanisms responsible for interannual variability of rainfall. WRF has a high skill in simulating the interannual variability of rainfall over the southeastern TP in July and August, but a low skill in June. The WRF's high skill is attributed to that the interannual variability of July–August rainfall is largely driven by large-scale circulation, while its low skill for June rainfall may be ascribed to the overestimation of snow and its relationship with rainfall. © 2018 Royal Meteorological Society" "57191370661;56250185400;7004020627;","Do new sea spray aerosol source functions improve the results of a regional aerosol model?",2019,"10.1016/j.atmosenv.2018.10.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056196528&doi=10.1016%2fj.atmosenv.2018.10.016&partnerID=40&md5=bdbd565dd7363bd077d70e7446c7abf5","Sea spray aerosol particle is a dominating part of the global aerosol mass load of natural origin. Thus, it strongly influences the atmospheric radiation balance and cloud properties especially over the oceans. Uncertainties of the estimated climate impacts by this aerosol type are partly caused by the uncertainties in the particle size dependent emission fluxes of sea spray aerosol particle. We present simulations with a regional aerosol transport model system in two domains, for three months and compared the model results to measurements at four stations using various sea spray aerosol particle source source functions. Despite these limitations we found the results using different source functions are within the range of most model uncertainties. Especially the model's ability to produce realistic wind speeds is crucial. Furthermore, the model results are more affected by a function correcting the emission flux for the effect of the sea surface temperature than by the use of different source functions. © 2018 The Authors" "57217124005;7102988363;37089417300;15127430500;55976582900;22979686100;15926468600;14058796400;57190130607;24477694300;18438062100;55917711400;","Global aerosol modeling with MADE3 (v3.0) in EMAC (based on v2.53): Model description and evaluation",2019,"10.5194/gmd-12-541-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061128902&doi=10.5194%2fgmd-12-541-2019&partnerID=40&md5=c1eec96e43e5c27d951c4e736a617801","Recently, the aerosol microphysics submodel MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, third generation) was introduced as a successor to MADE and MADE-in. It includes nine aerosol species and nine lognormal modes to represent aerosol particles of three different mixing states throughout the aerosol size spectrum. Here, we describe the implementation of the most recent version of MADE3 into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, including a detailed evaluation of a 10-year aerosol simulation with MADE3 as part of EMAC.We compare simulation output to station network measurements of near-surface aerosol component mass concentrations, to airborne measurements of aerosol mass mixing ratio and number concentration vertical profiles, to ground-based and airborne measurements of particle size distributions, and to station network and satellite measurements of aerosol optical depth. Furthermore, we describe and apply a new evaluation method, which allows a comparison of model output to size-resolved electron microscopy measurements of particle composition. Although there are indications that fine-mode particle deposition may be underestimated by the model, we obtained satisfactory agreement with the observations. Remaining deviations are of similar size to those identified in other global aerosol model studies.Thus, MADE3 can be considered ready for application within EMAC. Due to its detailed representation of aerosol mixing state, it is especially useful for simulating wet and dry removal of aerosol particles, aerosol-induced formation of cloud droplets and ice crystals as well as aerosol-radiation interactions. Besides studies on these fundamental processes, we also plan to use MADE3 for a reassessment of the climate effects of anthropogenic aerosol perturbations. © 2019 Author(s)." "57191608921;6602817918;19639722300;56472496900;36061813500;","Exploring the potential of satellite solar-induced fluorescence to constrain global transpiration estimates",2019,"10.3390/rs11040413","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062540427&doi=10.3390%2frs11040413&partnerID=40&md5=d4c56a1318144b1371f54b3b26ae4c49","The opening and closing of plant stomata regulates the global water, carbon and energy cycles. Biophysical feedbacks on climate are highly dependent on transpiration, which is mediated by vegetation phenology and plant responses to stress conditions. Here, we explore the potential of satellite observations of solar-induced chlorophyll fluorescence (SIF)-normalized by photosynthetically-active radiation (PAR)-to diagnose the ratio of transpiration to potential evaporation ('transpiration efficiency', τ). This potential is validated at 25 eddy-covariance sites from seven biomes worldwide. The skill of the state-of-the-art land surface models (LSMs) from the eartH2Observe project to estimate τ is also contrasted against eddy-covariance data. Despite its relatively coarse (0.5°) resolution, SIF/PAR estimates, based on data from the Global Ozone Monitoring Experiment 2 (GOME-2) and the Clouds and Earth's Radiant Energy System (CERES), correlate to the in situ τ significantly (average inter-site correlation of 0.59), with higher correlations during growing seasons (0.64) compared to decaying periods (0.53). In addition, the skill to diagnose the variability of in situ τ demonstrated by all LSMs is on average lower, indicating the potential of SIF data to constrain the formulations of transpiration in global models via, e.g., data assimilation. Overall, SIF/PAR estimates successfully capture the effect of phenological changes and environmental stress on natural ecosystem transpiration, adequately reflecting the timing of this variability without complex parameterizations. © 2019 by the authors." "56521532600;15026371500;","ITCZ width controls on Hadley cell extent and eddy-driven jet position and their response to warming",2019,"10.1175/JCLI-D-18-0434.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060974003&doi=10.1175%2fJCLI-D-18-0434.1&partnerID=40&md5=b6284a9992fa98b2143aecba5dbce898","The impact of global warming-induced intertropical convergence zone (ITCZ) narrowing onto the higherlatitude circulation is examined in the GFDL Atmospheric Model, version 2.1 (AM2.1), run over zonally symmetric aquaplanet boundary conditions.Astriking reconfiguration of the deep tropical precipitation from double-peaked, off-equatorial ascent to a single peak at the equator occurs under a globally uniform + 4Ksea surface temperature (SST) perturbation. This response is found to be highly sensitive to the SST profile used to force the model. By making small (≤1K) perturbations to the surface temperature in the deep tropics, varying control simulation precipitation patterns with both single and double ITCZs are generated. Across the climatologies, narrower regions of ascent correspond to more equatorward Hadley cell edges and eddydriven jets. Under the global warming perturbation, the experiments in which there is narrowing of the ITCZ show significantly less expansion of the Hadley cell and somewhat less poleward shift of the eddy-driven jet than those without ITCZ narrowing. With a narrower ITCZ, the ascending air has larger zonal momentum, causing more westerly upper-tropospheric subtropical wind. In turn, this implies 1) the subtropical jet will become baroclinically unstable at a lower latitude and 2) the critical (zero wind) line will shift equatorward, allowing midlatitude eddies to propagate farther equatorward. Both of these mechanisms modify the Hadley cell edge position, and the latter affects the jet position. © 2019 American Meteorological Society." "55871347000;7004060399;","Exploiting the abrupt 4 × CO 2 scenario to elucidate tropical expansion mechanisms",2019,"10.1175/JCLI-D-18-0330.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060530589&doi=10.1175%2fJCLI-D-18-0330.1&partnerID=40&md5=745a76bc957727d25bd4be1d10b65998","Future emissions of greenhouse gases into the atmosphere are projected to result in significant circulation changes. One of the most important changes is the widening of the tropical belt, which has great societal impacts. Several mechanisms (changes in surface temperature, eddy phase speed, tropopause height, and static stability) have been proposed to explain this widening. However, the coupling between these mechanisms has precluded elucidating their relative importance. Here, the abrupt quadrupled-CO 2 simulations of phase 5 of the Coupled Model Intercomparison Project (CMIP5) are used to examine the proposed mechanisms. The different time responses of the different mechanisms allow us to disentangle and evaluate them. As suggested by earlier studies, the Hadley cell edge is found to be linked to changes in subtropical baroclinicity. In particular, its poleward shift is accompanied by an increase in subtropical static stability (i.e., a decrease in temperature lapse rate) with increased CO 2 concentrations. These subtropical changes also affect the eddy momentum flux, which shifts poleward together with the Hadley cell edge. Transient changes in tropopause height, eddy phase speed, and surface temperature, however, were found not to accompany the poleward shift of the Hadley cell edge. The widening of the Hadley cell, together with the increase in moisture content, accounts for most of the expansion of the dry zone. Eddy moisture fluxes, on the other hand, are found to play a minor role in the expansion of the dry zone. © 2019 American Meteorological Society." "56514898500;7005123385;6506948406;55629846800;55417853000;","Variational deconvolution of conically scanned passive microwave observations with error quantification",2019,"10.1109/TGRS.2018.2864097","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053355598&doi=10.1109%2fTGRS.2018.2864097&partnerID=40&md5=36806d14fd390093b9c5723258ac86ed","The deconvolution of potentially cloud-affected passive microwave brightness temperatures is an important step for utilization in direct data assimilation in cloud-resolving numerical weather prediction (NWP) models for the purpose of improving model initial conditions. Geophysical retrieval algorithms, such as precipitation rate retrievals, also benefit from consistent resolution across channels. In this paper, we explore how to derive the posterior error estimates that are required for ingestion into data assimilation models or end-to-end error-quantified retrieval algorithms. To this end, we present a minimum variance, best linear-unbiased estimator approach that seeks an optimal estimate of the apparent (i.e., without the effects of antenna pattern convolution) brightness temperatures by iteratively minimizing a cost function measuring the lack of fit between observations and departures from a first guess. Both the observation and first-guess departure terms are weighed by a corresponding covariance term that estimates their relative uncertainty. The first-guess uncertainty, a Bayesian prior 'belief' in the spread of the first-guess error, is estimated using geophysical fields from an NWP model in a radiative transfer model plus an antenna pattern forward operator, then iteratively improved using the posterior deconvolved brightness temperatures of actual special sensor microwave imager/sounder observations. The error for the posterior distribution, subject to the initial belief, is derived. The error-quantified results are shown to increase the spatial resolution of microwave observations. © 2018 IEEE." "7404764644;7004698443;56486548700;57076999300;57203255846;38661149100;57190111640;7005870626;7006413710;56898191700;","Impact of insolation data source on remote sensing retrievals of evapotranspiration over the California delta",2019,"10.3390/rs11030216","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061375577&doi=10.3390%2frs11030216&partnerID=40&md5=465057b2843724bb27cc58af3fb2255c","The energy delivered to the land surface via insolation is a primary driver of evapotranspiration (ET)-the exchange of water vapor between the land and atmosphere. Spatially distributed ET products are in great demand in the water resource management community for real-time operations and sustainable water use planning. The accuracy and deliverability of these products are determined in part by the characteristics and quality of the insolation data sources used as input to the ETmodels. This paper investigates the practical utility of three different insolation datasets within the context of a satellite-based remote sensing framework for mapping ET at high spatiotemporal resolution, in an application over the Sacramento-San Joaquin Delta region in California. The datasets tested included one reanalysis product: The Climate System Forecast Reanalysis (CFSR) at 0.25° spatial resolution, and two remote sensing insolation products generated with geostationary satellite imagery: a product for the continental United States at 0.2°, developed by the University ofWisconsin Space Sciences and Engineering Center (SSEC) and a coarser resolution (1°) global Clouds and the Earth's Radiant Energy System(CERES) product. The three insolation data sources were compared to pyranometer data collected at flux towers within the Delta region to establish relative accuracy. The satellite products significantly outperformed CFSR, with root-mean square errors (RMSE) of 2.7, 1.5, and 1.4 MJ·m -2 ·d -1 for CFSR, CERES, and SSEC, respectively, at daily timesteps. The satellite-based products provided more accurate estimates of cloud occurrence and radiation transmission, while the reanalysis tended to underestimate solar radiation under cloudy-sky conditions. However, this difference in insolation performance did not translate into comparable improvement in the ET retrieval accuracy, where the RMSE in daily ET was 0.98 and 0.94 mm d -1 using the CFSR and SSEC insolation data sources, respectively, for all the flux sites combined. The lack of a notable impact on the aggregate ET performance may be due in part to the predominantly clear-sky conditions prevalent in central California, under which the reanalysis and satellite-based insolation data sources have comparable accuracy. While satellite-based insolation data could improve ET retrieval in more humid regions with greater cloud-cover frequency, over the California Delta and climatologically similar regions in the western U.S., the CFSR data may suffice for real-time ET modeling efforts. © 2019 by the authors." "35099355900;54401002500;7006621313;8277424000;8408994300;","A prognostic nested k-nearest approach for microwave precipitation phase detection over snow cover",2019,"10.1175/JHM-D-18-0021.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063590901&doi=10.1175%2fJHM-D-18-0021.1&partnerID=40&md5=237b89a5ece309e28743716d336e4bc4","Monitoring changes of precipitation phase from space is important for understanding the mass balance of Earth's cryosphere in a changing climate. This paper examines a Bayesian nearest neighbor approach for prognostic detection of precipitation and its phase using passive microwave observations from the Global Precipitation Measurement (GPM) satellite. The method uses the weighted Euclidean distance metric to search through an a priori database populated with coincident GPM radiometer and radar observations as well as ancillary snow-cover data. The algorithm performance is evaluated using data from GPM official precipitation products, ground-based radars, and high-fidelity simulations from the Weather Research and Forecasting Model. Using the presented approach, we demonstrate that the hit probability of terrestrial precipitation detection can reach to 0.80, while the probability of false alarm remains below 0.11. The algorithm demonstrates higher skill in detecting snowfall than rainfall, on average by 10%. In particular, the probability of precipitation detection and its solid phase increases by 11% and 8%, over dry snow cover, when compared to other surface types. The main reason is found to be related to the ability of the algorithm in capturing the signal of increased liquid water content in snowy clouds over radiometrically cold snow-covered surfaces. © 2019 American Meteorological Society." "57204897668;7403269234;","Glacier changes between 1971 and 2016 in the Jankar Chhu Watershed, Lahaul Himalaya, India",2019,"10.1017/jog.2018.77","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057729690&doi=10.1017%2fjog.2018.77&partnerID=40&md5=cd4f581689df986cb447e003c2b8b87c","Glacier changes in the Jankar Chhu Watershed (JCW) of Chandrabhaga (Chenab) basin, Lahaul Himalaya were worked out based on Corona and Sentinel 2A images between 1971 and 2016. The JCW consists of 153 glaciers (>0.02 km 2 ) with a total area of 185.6 ± 3.8 km 2 that include 82 glaciers with debris-covered ablation zone, comprising 10.9% of the total glacierized area as in 2016. Change analysis based on Corona (1971), Landsat (2000) and Sentinel 2A (2016) was restricted to 127 glaciers owing to the presence of cloud cover on 26 glaciers in 1971. A subset of glaciers was also mapped using Landsat Thematic Mapper (TM; 1989) image. The total glacier area decreased by 14.7 ± 4.3 km 2 (0.3 ± 0.1 km 2 a -1 ). The number of glaciers in the JCW increased by four between 1971 and 2016 due to fragmentation. More recently (2000-16), recession rate has increased. Clean-ice area decreased by 21.8 ± 3.8 km 2 (0.5 ± 0.1 km 2 a -1 ) while debris-covered ice increased by 7.2 ± 0.4 km 2 (0.2 ± 0.01 km 2 a -1 ;). Field observations of select glaciers also support derived recession trend in the JCW. Retreat rates in the JCW have been observed to be much lower than previously reported. Copyright © 2018 The Author(s)." "56205996400;57205657272;25623929200;55359774700;36480034300;","Monitoring the characteristics of the bohai sea ice using high-resolution geostationary ocean color imager (GOCI) data",2019,"10.3390/su11030777","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060969602&doi=10.3390%2fsu11030777&partnerID=40&md5=ccd9bc78c47d96c5a148c7c0ba0e511a","Satellite remote sensing data, such as moderate resolution imaging spectroradiometers (MODIS) and advanced very high-resolution radiometers (AVHRR), are being widely used to monitor sea ice conditions and their variability in the Bohai Sea, the southernmost frozen sea in the Northern Hemisphere. Monitoring the characteristics of the Bohai Sea ice can provide crucial information for ice disaster prevention for marine transportation, oil field operation, and regional climate change studies. Although these satellite data cover the study area with fairly high spatial resolution, their typically limited cloudless images pose serious restrictions for continuous observation of short-term dynamics, such as sub-seasonal changes. In this study, high spatiotemporal resolution (500 m and eight images per day) geostationary ocean color imager (GOCI) data with a high proportion of cloud-free images were used to monitor the characteristics of the Bohai Sea ice, including area and thickness. An object-based feature extraction method and an albedo-based thickness inversion model were used for estimating sea ice area and thickness, respectively. To demonstrate the efficacy of the new dataset, a total of 68 GOCI images were selected to analyze the evolution of sea ice area and thickness during the winter of 2012-2013 with severe sea ice conditions. The extracted sea ice area was validated using Landsat Thematic Mapper (TM) data with higher spatial resolution, and the estimated sea ice thickness was found to be consistent with in situ observation results. The entire sea ice freezing-melting processes, including the key events such as the day with the maximum ice area and the first and last days of the frozen season, were better resolved by the high temporal-resolution GOCI data compared with MODIS or AVHRR data. Both characteristics were found to be closely correlated with cumulative freezing/melting degree days. Our study demonstrates the applicability of the GOCI data as an improved dataset for studying the Bohai Sea ice, particularly for purposes that require high temporal resolution data, such as sea ice disaster monitoring. © 2019 by the authors." "6602164207;55334146100;57204034004;7409608104;","The ability of moderate resolution imaging spectroradiometer land surface temperatures to simulate cold air drainage and microclimates in complex Arctic terrain",2019,"10.1002/joc.5854","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054193171&doi=10.1002%2fjoc.5854&partnerID=40&md5=0f28716ccb4ca87b6a01dfad6cc8e0c4","The Arctic has experienced the most rapid warming in the world in recent decades. Complex topography combines with low solar elevation to create distinct microclimates in Arctic regions, and for many applications such as ecological response and cryospheric change it is critical to obtain reliable temperature trends at the local scale. Due to lack of weather stations, satellite land surface temperature (LST) is increasingly important as a proxy for air temperature (T air ), but how accurately it can represent microclimates is unknown. For the first time, we compare 10 years (2007–2017) of T air recorded over a dense network of 65 sites (~25 km 2 ) around Kevo Subarctic Research Station in Finland with equivalent moderate resolution imaging spectroradiometer (MODIS) LST at 1 km resolution from MOD11A2/MYD11A2 8-day products. We assess whether LST can pick up the extreme local gradients in air temperature (>20 °C/km) caused by cold air drainage. Although there is a high correspondence between LST and T air anomalies on a synoptic timescale, small-scale patterns in T air (lapse rates, aspect contrasts) are not picked up by LST. Temperature gradients in T air become positive (temperature inversions) in winter, and at night, but LST gradients show almost the reverse. Aspect contrasts in T air peak in spring and autumn during the day, but LST shows biggest differences in the evening. Land cover has a large influence on LST, tundra heating up/cooling down more than birch or pine forest. The conflation between land cover and elevation means that differential land-cover response dominates the elevational LST signal. Contrasts between T air and LST cannot be explained by the number of stations measuring T air in a pixel, elevation error, timing differences or the frequency of cloud cover within the 8-day composite. Important features of the Arctic climate such as microscale cold air drainage are thus potentially obscured by land-cover effects. © 2018 Royal Meteorological Society" "55438887500;7404481178;36899513900;57203012951;57212184289;56157881200;57207932942;57194038742;","Using MODIS/Terra and Landsat imageries to improve surface water quantification in Sylhet, Bangladesh",2019,"10.3319/TAO.2018.11.15.04","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063282390&doi=10.3319%2fTAO.2018.11.15.04&partnerID=40&md5=f29cda186ee42db427f657ad94718600","Bangladesh has experienced multiple freshwater issues including salinization from monsoonal floods and groundwater over-pumping that induces severe land subsidence. Therefore, using satellite observations to virtually build a monitoring network becomes an efficient and innovative means. We focus on the Sylhet Mymensingh haor area that has the highest annual precipitation and the largest inundation area in northeastern Bangladesh. The modified normalized difference water index is first used to extract water area from MODIS and Landsat-5/-7/-8 optical imageries. A weekly flood chance model is then created from a sequence of images to recover water extent from the cloud-covered images. Using MODIS images for water identification achieves an overall accuracy of 84% in rainy season and 41% in dry season as validated with Sentinel-1A radar images. This model can be further used to refine the Shuttle Radar Topography Mission digital elevation model (DEM). As compared with ICESat laser altimetry, the root-mean-square of the height difference is improved from 1.65 - 1.16 m after DEM modification. By combining the recovered water area and the refined DEM, surface water volume (WV) is quantified. A comparison with the Gravity Recovery And Climate Experiment (GRACE) gravimetry retrieved equivalent water heights (EWHs) in 2002 - 2015 is conducted, where the correlation coefficient and root-mean-square of the equivalent water height (EWH) difference are 91.7% and 0.09 m, respectively. © 2019 Chinese Geoscience Union. All rights reserved." "53881551800;7006058741;7202526339;","Automated detection of thermoerosion in permafrost ecosystems using temporally dense Landsat image stacks",2019,"10.1016/j.rse.2018.11.034","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057807722&doi=10.1016%2fj.rse.2018.11.034&partnerID=40&md5=1e166913f23e96f6242a801e0530e803","Anthropogenic climate change has been linked to the degradation of permafrost across northern ecosystems, with notable implications for regional to global carbon dynamics. However, our understanding of the spatial distribution, temporal trends, and seasonal timing of episodic landscape deformation events triggered by permafrost degradation is hampered by the limited spatial and temporal coverage of high-resolution optical, RADAR, LIDAR, and hyperspectral remote sensing products. Here we present an automated approach for detecting permafrost degradation (thermoerosion), using meso-scale high-frequency remote sensing products (i.e., Landsat image archive). This approach was developed, tested, and applied in the ice-rich lowlands of the Noatak National Preserve (NOAT; 12,369 km2) in northwestern Alaska. We identified thermoerosion (TE) by capturing the spectral signal associated with episodic sediment plumes in adjacent water bodies following TE. We characterized and extracted this episodic turbidity signal within lakes during the snow-free period (June 15–October 1) for 1986–2016 (continuous data limited to 1999–2016), using the cloud-based geospatial parallel processing platform, Google Earth Engine™. Thermoerosional detection accuracy was calculated using seven consecutive years of sub-meter high-resolution imagery (2009–2015) covering 798 (~33%) of the 2456 lakes in the NOAT lowlands. Our automated TE detection algorithm had an overall accuracy and kappa coefficient of 86% and 0.47 ± 0.043, indicating that episodic sediment pulses had a “moderate agreement” with landscape deformation associated with permafrost degradation. We estimate that lake shoreline erosion, thaw slumps, catastrophic lake drainage, and gully formation accounted for 62, 23, 13, and 2%, respectively, of active TE across the NOAT lowlands. TE was identified in ~5% of all lakes annually in the lowlands between 1999 and 2016, with a wide range of inter-annual variation (ranging from 0.2% in 2001 to 22% in 2004). Inter-annual variability in TE occurrence and spatial patterns of TE probability were correlated with annual snow cover duration and snow persistence, respectively, suggesting that earlier snowmelt accelerates permafrost degradation (e.g. TE) in this region. This work improves our ability to detect and attribute change in permafrost degradation across space and time. © 2018" "56088790300;56638491500;35389967500;","Large lake gauging using fractional imagery",2019,"10.1016/j.jenvman.2018.10.044","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057153015&doi=10.1016%2fj.jenvman.2018.10.044&partnerID=40&md5=2189cc294118c6b30e413a74178a5b7b","Large floodplain lakes provide riparian habitat, are sediment and nutrient sinks, help control flow connectivity and flooding along rivers, and are both used by humans and strongly impacted by human activity. However, water level in many remote large floodplain lakes, especially in developing countries, is often monitored inconsistently or not at all. In this study, a novel method for estimating large lake water level using passive, optical remote sensing data combined with any digital elevation model (DEM) is presented. The method obtains water level estimates at 30 m2 resolution using Landsat, in this case in conjunction with SRTM elevation data, nested within a 240 m2 grid “fishnet”. A probabilistic mean of elevation values for all water-designated pixels (between 5% and 95% filled within each grid) produces lake water levels often accurate to within ±50 cm of gauged reference data on Lake Curuai in the Amazon River and Tonle Sap Lake along the Mekong River. The method is relatively insensitive to cloud cover, especially as lake size increases. This study is the first to use solely passive optical remote sensing data for water level estimation and thus could be used to produce accurate, long-term estimations of water level in many large lakes globally. The use of optical sensors to obtain lake water level is both an important complement and potential alternative to methods that use active sensors. © 2018 Elsevier Ltd" "13007286600;8535697200;24821482700;7004713805;35222007100;36169987600;43461659100;23571250400;","The effects of simulating volcanic aerosol radiative feedbacks with WRF-Chem during the EyjafjallajÖkull eruption, April and May 2010",2019,"10.1016/j.atmosenv.2018.10.058","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055995786&doi=10.1016%2fj.atmosenv.2018.10.058&partnerID=40&md5=844c2752f56fe8d7380c9afb83827009","Explosive volcanic eruptions can inject large amounts of ash and gases into the atmosphere. Such volcanic aerosols can have a significant impact on the surrounding environment, and there is the need to closely investigate their effects on meteorology on local, regional, and even continental scale. This work presents a study of the 2010 Eyjafjallajökull volcanic eruption the resulting ash dispersion and its radiative feedback effects on the meteorological conditions with the Weather Research Forecasting model with on-line Chemistry (WRF-Chem). Two model runs, one meteorology-only simulation (without chemistry) and one that considers gas- and aerosol chemistry as well as direct- and semidirect aerosol feedbacks were performed and compared. Results for daily values show that aerosol radiative feedback effects can cool the atmosphere close to the surface on average by 1 °C with maximum cooling exceeding even 2 °C for the considered episode. Near-surface atmospheric wind speed changed on average by 0.5 m/s with maximum values above 2 m/s. Furthermore, the presence of ash aerosols affected the vertical shape of the profiles of wind speed and temperature and resulted in a better agreement with radiosonde measurements when radiative feedback effects were considered. Although the modeling of the dispersion of volcanic ash clouds is subject to large uncertainties, we have demonstrated that the WRF-Chem model can reproduce observations at surface levels and vertical profiles more realistically when radiative feedback effects are considered in the simulations. © 2018 The Authors" "55261725400;36005104100;","Radiometry calibration with high-resolution profiles of GPM: Application to ATMS 183-GHz water vapor channels and comparison against reanalysis profiles",2019,"10.1109/TGRS.2018.2861678","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051835035&doi=10.1109%2fTGRS.2018.2861678&partnerID=40&md5=70eca6271b7d14fcb6cf58516dc28e31","The reanalysis data produced by numerical weather prediction (NWP) models and data assimilation have been widely used for radiometer calibration. They provide atmospheric profiles that are necessary for radiative transfer simulation against observation. However, there are biases and uncertainties in the reanalysis due to NWP model mechanism, parameterization, boundary conditions, and assimilation skills. As spaceborne radiometer data have been used in deriving reanalyses, reanalyses are not independent of these radiometers and should be used with caution when used as reference for radiometer calibration. In addition, these data often have coarse spatial (100 km horizontally) and temporal resolution (6 h). An independent data set with high resolution can be very useful to diagnose reanalyses and might improve calibration. The Global Precipitation Measurement (GPM) core observatory measures atmospheric water signatures with an onboard radar and radiometer. A GPM data set including atmospheric water vapor, cloud liquid water, and precipitation has been produced based on observational retrieval with high spatiotemporal resolution (5 km horizontally and 250 m vertically). We have developed a scheme to ingest the high-resolution GPM profiles and perform rigorous simulation and calibration taking into account the radiometer spectral response function, footprint size variation, and antenna pattern. GPM data exhibit different water vapor profiles and weighting functions from reanalyses. It produces overall consistent results of calibration as reanalyses and outperforms them in some aspects. The GPM profiles and our scheme are very useful and will be routinely applied to monitor Advanced Technology Microwave Sounder inflight status. © 2018 IEEE." "34871696700;55886067800;7102944401;57188721115;6603102974;36957287400;24829503600;7006107059;","Open fires in Greenland in summer 2017: Transport, deposition and radiative effects of BC, OC and BrC emissions",2019,"10.5194/acp-19-1393-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061059352&doi=10.5194%2facp-19-1393-2019&partnerID=40&md5=95b153d67408f0f94a019b5a037604d4","Highly unusual open fires burned in western Greenland between 31 July and 21 August 2017, after a period of warm, dry and sunny weather. The fires burned on peatlands that became vulnerable to fires by permafrost thawing. We used several satellite data sets to estimate that the total area burned was about 2345 ha. Based on assumptions of typical burn depths and emission factors for peat fires, we estimate that the fires consumed a fuel amount of about 117 kt C and emitted about 23.5 t of black carbon (BC) and 731 t of organic carbon (OC), including 141 t of brown carbon (BrC). We used a Lagrangian particle dispersion model to simulate the atmospheric transport and deposition of these species. We find that the smoke plumes were often pushed towards the Greenland ice sheet by westerly winds, and thus a large fraction of the emissions (30 %) was deposited on snow- or ice-covered surfaces. The calculated deposition was small compared to the deposition from global sources, but not entirely negligible. Analysis of aerosol optical depth data from three sites in western Greenland in August 2017 showed strong influence of forest fire plumes from Canada, but little impact of the Greenland fires. Nevertheless, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar data showed that our model captured the presence and structure of the plume from the Greenland fires. The albedo changes and instantaneous surface radiative forcing in Greenland due to the fire emissions were estimated with the SNICAR model and the uvspec model from the libRadtran radiative transfer software package. We estimate that the maximum albedo change due to the BC and BrC deposition was about 0.007, too small to be measured. The average instantaneous surface radiative forcing over Greenland at noon on 31 August was 0.03-0.04 W m -2 , with locally occurring maxima of 0.63-0.77 W m -2 (depending on the studied scenario). The average value is up to an order of magnitude smaller than the radiative forcing from other sources. Overall, the fires burning in Greenland in the summer of 2017 had little impact on the Greenland ice sheet, causing a small extra radiative forcing. This was due to the - in a global context - still rather small size of the fires. However, the very large fraction of the emissions deposited on the Greenland ice sheet from these fires could contribute to accelerated melting of the Greenland ice sheet if these fires become several orders of magnitude larger under future climate. © Author(s) 2019." "35794588800;7102805852;56219722000;9941600400;10139397300;6603113016;7004864963;","Studying the impact of biomass burning aerosol radiative and climate effects on the Amazon rainforest productivity with an Earth system model",2019,"10.5194/acp-19-1301-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061015260&doi=10.5194%2facp-19-1301-2019&partnerID=40&md5=cfd53cd8c38c40e40de4c94339750b0c","Diffuse light conditions can increase the efficiency of photosynthesis and carbon uptake by vegetation canopies. The diffuse fraction of photosynthetically active radiation (PAR) can be affected by either a change in the atmospheric aerosol burden and/or a change in cloudiness. During the dry season, a hotspot of biomass burning on the edges of the Amazon rainforest emits a complex mixture of aerosols and their precursors and climate-active trace gases (e.g. CO 2 , CH 4 , NO x ). This creates potential for significant interactions between chemistry, aerosol, cloud, radiation and the biosphere across the Amazon region. The combined effects of biomass burning on the terrestrial carbon cycle for the present day are potentially large, yet poorly quantified. Here, we quantify such effects using the Met Office Hadley Centre Earth system model HadGEM2-ES, which provides a fully coupled framework with interactive aerosol, radiative transfer, dynamic vegetation, atmospheric chemistry and biogenic volatile organic compound emission components. Results show that for present day, defined as year 2000 climate, the overall net impact of biomass burning aerosols is to increase net primary productivity (NPP) by +80 to +105 TgC yr -1 , or 1.9% to 2.7 %, over the central Amazon Basin on annual mean. For the first time we show that this enhancement is the net result of multiple competing effects: an increase in diffuse light which stimulates photosynthetic activity in the shaded part of the canopy (+65 to +110 TgC yr -1 ), a reduction in the total amount of radiation (-52 to -1 05 TgC yr -1 ) which reduces photosynthesis and feedback from climate adjustments in response to the aerosol forcing which increases the efficiency of biochemical processes (+67 to +100 TgC yr -1 ). These results illustrate that despite a modest direct aerosol effect (the sum of the first two counteracting mechanisms), the overall net impact of biomass burning aerosols on vegetation is sizeable when indirect climate feedbacks are considered. We demonstrate that capturing the net impact of aerosols on vegetation should be assessed considering the system-wide behaviour. © Author(s) 2019." "56457851700;7103016965;25924878400;13402835300;7102171439;26645289600;22934904700;8696069500;55325157500;7404029779;6602887222;23012746800;55885528600;6603718837;24764483400;7801353107;18635820300;","Cloud feedbacks in extratropical cyclones: Insight from long-term satellite data and high-resolution global simulations",2019,"10.5194/acp-19-1147-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060956582&doi=10.5194%2facp-19-1147-2019&partnerID=40&md5=02664cbd6068789bdc44ae62953a0269","A negative extratropical shortwave cloud feedback driven by changes in cloud optical depth is a feature of global climate models (GCMs). A robust positive trend in observed liquid water path (LWP) over the last two decades across the warming Southern Ocean supports the negative shortwave cloud feedback predicted by GCMs. This feature has been proposed to be due to transitions from ice to liquid with warming. To gain insight into the shortwave cloud feedback we examine extratropical cyclone variability and the response of extratropical cyclones to transient warming in GCM simulations. Multi-Sensor Advanced Climatology Liquid Water Path (MAC-LWP) microwave observations of cyclone properties from the period 1992-2015 are contrasted with GCM simulations, with horizontal resolutions ranging from 7 km to hundreds of kilometers. We find that inter-cyclone variability in LWP in both observations and models is strongly driven by the moisture flux along the cyclone's warm conveyor belt (WCB). Stronger WCB moisture flux enhances the LWP within cyclones. This relationship is replicated in GCMs, although its strength varies substantially across models. It is found that more than 80 % of the enhancement in Southern Hemisphere (SH) extratropical cyclone LWP in GCMs in response to a transient 4 K warming can be predicted based on the relationship between the WCB moisture flux and cyclone LWP in the historical climate and their change in moisture flux between the historical and warmed climates. Further, it is found that that the robust trend in cyclone LWP over the Southern Ocean in observations and GCMs is consistent with changes in the moisture flux. We propose two cloud feedbacks acting within extratropical cyclones: a negative feedback driven by Clausius-Clapeyron increasing water vapor path (WVP), which enhances the amount of water vapor available to be fluxed into the cyclone, and a feedback moderated by changes in the life cycle and vorticity of cyclones under warming, which changes the rate at which existing moisture is imported into the cyclone. Both terms contribute to increasing LWP within the cyclone. While changes in moisture flux predict cyclone LWP trends in the current climate and the majority of changes in LWP in transient warming simulations, a portion of the LWP increase in response to climate change that is unexplained by increasing moisture fluxes may be due to phase transitions. The variability in LWP within cyclone composites is examined to understand what cyclonic regimes the mixed-phase cloud feedback is relevant to. At a fixed WCB moisture flux cyclone LWP increases with increasing sea surface temperature (SST) in the half of the composite poleward of the low and decreases in the half equatorward of the low in both GCMs and observations. Cloud-top phase partitioning observed by the Atmospheric Infrared Sounder (AIRS) indicates that phase transitions may be driving increases in LWP in the poleward half of cyclones. © Author(s) 2019." "24780734700;35995806700;55371421300;53163712400;7202441181;55857096100;36244268000;6602205640;7004035832;25624173600;57205728958;7202821735;","Bryophyte stable isotope composition, diversity and biomass define tropical montane cloud forest extent",2019,"10.1098/rspb.2018.2284","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061307399&doi=10.1098%2frspb.2018.2284&partnerID=40&md5=2d0a3e3dc856b92fc1df1d07df58ce56","Liverworts and mosses are a major component of the epiphyte flora of tropical montane forest ecosystems. Canopy access was used to analyse the distribution and vertical stratification of bryophyte epiphytes within tree crowns at nine forest sites across a 3400 m elevational gradient in Peru, from the Amazonian basin to the high Andes. The stable isotope compositions of bryophyte organic material ( 13 C/ 12 C and 18 O/ 16 O) are associated with surface water diffusive limitations and, along with C/N content, provide a generic index for the extent of cloud immersion. From lowland to cloud forest d 13 C increased from 233 to 227, while d 18 O increased from 16.3 to 18.0. Epiphytic bryophyte and associated canopy soil biomass in the cloud immersion zone was estimated at up to 45 t dry mass ha 21 , and overall water holding capacity was equivalent to a 20 mm precipitation event. The study emphasizes the importance of diverse bryophyte communities in sequestering carbon in threatened habitats, with stable isotope analysis allowing future elevational shifts in the cloud base associated with changes in climate to be tracked. © 2019 The Author(s) Published by the Royal Society. All rights reserved." "6505806236;26663613300;57200694547;55133977300;24553952400;55921875600;7202060681;37023271100;57205597167;57193550601;24777603300;","A General Lake Model (GLM 3.0) for linking with high-frequency sensor data from the Global Lake Ecological Observatory Network (GLEON)",2019,"10.5194/gmd-12-473-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060735260&doi=10.5194%2fgmd-12-473-2019&partnerID=40&md5=771d574de38da6cb8230a2b8272f88be","The General Lake Model (GLM) is a one-dimensional open-source code designed to simulate the hydrodynamics of lakes, reservoirs, and wetlands. GLM was developed to support the science needs of the Global Lake Ecological Observatory Network (GLEON), a network of researchers using sensors to understand lake functioning and address questions about how lakes around the world respond to climate and land use change. The scale and diversity of lake types, locations, and sizes, and the expanding observational datasets created the need for a robust community model of lake dynamics with sufficient flexibility to accommodate a range of scientific and management questions relevant to the GLEON community. This paper summarizes the scientific basis and numerical implementation of the model algorithms, including details of sub-models that simulate surface heat exchange and ice cover dynamics, vertical mixing, and inflow-outflow dynamics. We demonstrate the suitability of the model for different lake types that vary substantially in their morphology, hydrology, and climatic conditions. GLM supports a dynamic coupling with biogeochemical and ecological modelling libraries for integrated simulations of water quality and ecosystem health, and options for integration with other environmental models are outlined. Finally, we discuss utilities for the analysis of model outputs and uncertainty assessments, model operation within a distributed cloud-computing environment, and as a tool to support the learning of network participants. © 2019 Author(s)." "57189487979;7005902717;","Precipitation δ 18 O on the Himalaya-Tibet orogeny and its relationship to surface elevation",2019,"10.5194/cp-15-169-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060844948&doi=10.5194%2fcp-15-169-2019&partnerID=40&md5=a604c05553d5ff435ef36b6bbc81a93e","The elevation history of the Himalaya-Tibet orogen is central to understanding the evolution and dynamics of both the India-Asia collision and the Asian monsoons. The surface elevation history of the region is largely deduced from stable isotope (δ 18 O, δD) paleoaltimetry. This method is based on the observed relationship between the isotopic composition of meteoric waters (δ 18 O p , δD p ) and surface elevation, and the assumption that precipitation undergoes Rayleigh distillation under forced ascent. Here we evaluate how elevation-induced climate change influences the δ 18 Op-elevation relationship and whether Rayleigh distillation is the dominant process affecting δ 18 O p . We use an isotope-enabled climate model, ECHAM-wiso, to show that the Rayleigh distillation process is only dominant in the monsoonal regions of the Himalayas when the mountains are high. When the orogen is lowered, local surface recycling and convective processes become important, as forced ascent is weakened due to weaker Asian monsoons. As a result, the δ 18 O p lapse rate in the Himalayas increases from around -3 to above -0.1‰km, and has little relationship with elevation. On the Tibetan Plateau, the meridional gradient of δ 18 O decreases from ∼ 1 to ∼ 0.3‰ o-1 with reduced elevation, primarily due to enhanced sub-cloud reevaporation under lower relative humidity. Overall, we report that using δ 18 O p or δD p to deduce surface elevation change in the Himalayan-Tibetan region has severe limitations and demonstrate that the processes that control annual-mean precipitation-weighted δ 18 O p vary by region and with surface elevation. In summary, we determine that the application of δ 18 O paleoaltimetry is only appropriate for 7 of the 50 sites from which δ 18 O records have been used to infer past elevations. © Author(s) 2019." "56722821200;55816227500;15755995900;7005920812;56162305900;7401796996;57201399639;","Subgrid variations of the cloud water and droplet number concentration over the tropical ocean: Satellite observations and implications for warm rain simulations in climate models",2019,"10.5194/acp-19-1077-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060790407&doi=10.5194%2facp-19-1077-2019&partnerID=40&md5=5b7b5ef8a265cbdb95c365c07d32e46c","One of the challenges in representing warm rain processes in global climate models (GCMs) is related to the representation of the subgrid variability of cloud properties, such as cloud water and cloud droplet number concentration (CDNC), and the effect thereof on individual precipitation processes such as autoconversion. This effect is conventionally treated by multiplying the resolved-scale warm rain process rates by an enhancement factor (Eq ) which is derived from integrating over an assumed subgrid cloud water distribution. The assumed subgrid cloud distribution remains highly uncertain. In this study, we derive the subgrid variations of liquid-phase cloud properties over the tropical ocean using the satellite remote sensing products from Moderate Resolution Imaging Spectroradiometer (MODIS) and investigate the corresponding enhancement factors for the GCM parameterization of autoconversion rate. We find that the conventional approach of using only subgrid variability of cloud water is insufficient and that the subgrid variability of CDNC, as well as the correlation between the two, is also important for correctly simulating the autoconversion process in GCMs. Using the MODIS data which have near-global data coverage, we find that Eq shows a strong dependence on cloud regimes due to the fact that the subgrid variability of cloud water and CDNC is regime dependent. Our analysis shows a significant increase of Eq from the stratocumulus (Sc) to cumulus (Cu) regions. Furthermore, the enhancement factor EN due to the subgrid variation of CDNC is derived from satellite observation for the first time, and results reveal several regions downwind of biomass burning aerosols (e.g., Gulf of Guinea, east coast of South Africa), air pollution (i.e., East China Sea), and active volcanos (e.g., Kilauea, Hawaii, and Ambae, Vanuatu), where the EN is comparable to or even larger than Eq , suggesting an important role of aerosol in influencing the EN. MODIS observations suggest that the subgrid variations of cloud liquid water path (LWP) and CDNC are generally positively correlated. As a result, the combined enhancement factor, including the effect of LWP and CDNC correlation, is significantly smaller than the simple product of Eq-EN. Given the importance of warm rain processes in understanding the Earth's system dynamics and water cycle, we conclude that more observational studies are needed to provide a better constraint on the warm rain processes in GCMs. © Author(s) 2019." "55871347000;7004060399;7003843648;","The Effect of Arctic Sea Ice Loss on the Hadley Circulation",2019,"10.1029/2018GL081110","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060943880&doi=10.1029%2f2018GL081110&partnerID=40&md5=0f19af5acfdd77e381fd209d6bf5f9ec","One of the most robust responses of the climate system to future greenhouse gas emissions is the melting of Arctic sea ice. It is thus essential to elucidate its impacts on other components of the climate system. Here we focus on the response of the annual mean Hadley cell (HC) to Arctic sea ice loss using a hierarchy of model configurations: atmosphere only, atmosphere coupled to a slab ocean, and atmosphere coupled to a full-physics ocean. In response to Arctic sea ice loss, as projected by the end of the 21st century, the HC shows negligible changes in the absence of ocean-atmosphere coupling. In contrast, by warming the Northern Hemisphere thermodynamic coupling weakens the HC and expands it northward. However, dynamic coupling acts to cool the Northern Hemisphere which cancels most of this weakening and narrows the HC, thus opposing its projected expansion in response to increasing greenhouse gases. ©2019. American Geophysical Union. All Rights Reserved." "57188924386;57203030873;57194876603;6603925960;57193321831;","Cloud Response to Arctic Sea Ice Loss and Implications for Future Feedback in the CESM1 Climate Model",2019,"10.1029/2018JD029142","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060346657&doi=10.1029%2f2018JD029142&partnerID=40&md5=e4212f41aec0324fcf57444acfaf1349","Over the next century, the Arctic is projected to become seasonally sea ice-free. Assessing feedback between clouds and sea ice as the Arctic loses sea ice cover is important because of clouds' radiative impacts on the Arctic surface. Here we investigate present-day and future Arctic cloud-sea ice relationships in a fully coupled global climate model forced by business-as-usual increases in greenhouse gases. Model evaluation using a lidar simulator and lidar satellite observations shows agreement between present-day modeled and observed cloud-sea ice relationships. Summer clouds are unaffected by sea ice variability, but more fall clouds occur over open water than over sea ice. Because the model reproduces observed cloud-sea ice relationships and their underlying physical mechanisms, the model is used to assess future Arctic cloud-sea ice feedback. With future sea ice loss, modeled summer cloud fraction, vertical structure, and optical depth barely change. Future sea ice loss does not influence summer clouds, but summer sea ice loss does drive fall cloud changes by increasing the amount of sunlight absorbed by the summertime ocean and the latent and sensible heat released into the atmosphere when the Sun sets in fall. The future fall boundary layer deepens and clouds become more opaque over newly open water. The future nonsummer longwave cloud radiative effect strengthens as nonsummer cloud cover increases. In summary, we find no evidence for a summer cloud-sea ice feedback but strong evidence for a positive cloud-sea ice feedback that emerges during nonsummer months as the Arctic warms and sea ice disappears. ©2018. American Geophysical Union. All Rights Reserved." "57195922668;8511991900;42062523800;7103158465;7406215388;55723061900;7401796996;8658386900;7005742394;6603381720;9239331500;35744191200;7403077486;","Cloud-Resolving Model Intercomparison of an MC3E Squall Line Case: Part II. Stratiform Precipitation Properties",2019,"10.1029/2018JD029596","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060791960&doi=10.1029%2f2018JD029596&partnerID=40&md5=df460873ee091cc037e209101c47b5e2","In this second part of a cloud microphysics scheme intercomparison study, we focus on biases and variabilities of stratiform precipitation properties for a midlatitude squall line event simulated with a cloud-resolving model implemented with eight cloud microphysics schemes. Most of the microphysics schemes underestimate total stratiform precipitation, mainly due to underestimation of stratiform precipitation area. All schemes underestimate the frequency of moderate stratiform rain rates (2–6 mm/hr), which may result from low-biased ice number and mass concentrations for 0.2–2-mm diameter particles in the stratiform ice region. Most simulations overestimate ice water content (IWC) at altitudes above 7 km for temperatures colder than −20 °C but produce a decrease of IWC approaching the melting level, which is opposite to the trend shown by in situ observations. This leads to general underestimations of stratiform IWC below 5-km altitude and rainwater content above 1-km altitude for a given rain rate. Stratiform precipitation area positively correlates with the convective condensate detrainment flux but is modulated by hydrometeor type, size, and fall speed. Stratiform precipitation area also changes by up to 17%–25% through alterations of the lateral boundary condition forcing frequency. Stratiform precipitation, rain rate, and area across the simulations vary by a factor of 1.5. This large variability is primarily a result of variability in the stratiform downward ice mass flux, which is highly correlated with convective condensate horizontal detrainment strength. The variability of simulated local microphysical processes in the stratiform region plays a secondary role in explaining variability in simulated stratiform rainfall properties. ©2019. The Authors." "57194701835;34768438000;7501704796;36551761100;35181109400;22234817900;","Variations of Lake Ice Phenology on the Tibetan Plateau From 2001 to 2017 Based on MODIS Data",2019,"10.1029/2018JD028993","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060783643&doi=10.1029%2f2018JD028993&partnerID=40&md5=54699c20e8337e89cb99a7548219cbb7","Lake ice is a robust indicator of climate change. The availability of information contained in Moderate Resolution Imaging Spectroradiometer daily snow products from 2000 to 2017 could be greatly improved after cloud removal by gap filling. Thresholds based on open water pixel numbers are used to extract the freezeup start and breakup end dates for 58 lakes on the Tibetan Plateau (TP); 18 lakes are also selected to extract the freezeup end and breakup start dates. The lake ice durations are further calculated based on freezeup and breakup dates. Lakes on the TP begin to freezeup in late October and all the lakes start the ice cover period in mid-January of the following year. In late March, some lakes begin to break up, and all the lakes end the ice cover period in early July. Generally, the lakes in the northern Inner-TP have earlier freezeup dates and later breakup dates (i.e., longer ice cover durations) than those in the southern Inner-TP. Over 17 years, the mean ice cover duration of 58 lakes is 157.78 days, 18 (31%) lakes have a mean extending rate of 1.11 day/year, and 40 (69%) lakes have a mean shortening rate of 0.80 day/year. Geographical location and climate conditions determine the spatial heterogeneity of the lake ice phenology, especially the ones of breakup dates, while the physico-chemical characteristics mainly affect the freezeup dates of the lake ice in this study. Ice cover duration is affected by both climatic and lake specific physico-chemical factors, which can reflect the climatic and environmental change for lakes on the TP. ©2019. American Geophysical Union. All Rights Reserved." "56096442500;6602377428;6603472580;23466744600;56260361400;","Quantifying the Clear-Sky Bias of Satellite Land Surface Temperature Using Microwave-Based Estimates",2019,"10.1029/2018JD029354","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060802982&doi=10.1029%2f2018JD029354&partnerID=40&md5=4b5b9118746973b258eaf5a70320b7a8","Most available long-term databases of land surface temperature (LST) derived from space-borne sensors rely on infrared observations and are therefore restricted to clear-sky conditions. Hence, studies based on such data sets may not be representative of all-weather conditions and may be considered as “biased” toward clear sky. An assessment of the impact of this restriction is made using 3 years of LST derived from passive microwave observations that are not affected by most clouds. A systematic analysis in space and time is performed of the “clear-sky bias,” defined as the difference between average clear-sky and average all-weather LSTs. The amplitude of the bias is closely related to the fraction of clear-sky days, and therefore, arid regions are associated to very low values of bias whereas midlatitudes present the highest values. During daytime, the input of solar radiation for clear-sky situations leads to higher LST values, and therefore, the bias is generally positive (e.g., 2–8 K over the midlatitudes) whereas, during nighttime, the bias is generally negative although with lower amplitude (around −2 K), because of the increased radiative cooling for clear-sky situations. The clear-, cloudy-, and all-sky LSTs are also compared with near-surface air temperature. Although LST is generally higher than air temperature, the contrast between the two may be strongly influenced by local weather conditions. Both the clear-sky bias and differences between LST and air temperature are also analyzed at the local scale taking into account the predominant cloud regime. ©2019. American Geophysical Union. All Rights Reserved." "57203053066;36671874400;16475714800;56674819000;","Tropical cyclogenesis in warm climates simulated by a cloud-system resolving model",2019,"10.1007/s00382-018-4134-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046020931&doi=10.1007%2fs00382-018-4134-2&partnerID=40&md5=c7ac2d79b0922505976b8289e145f524","Here we investigate tropical cyclogenesis in warm climates, focusing on the effect of reduced equator-to-pole temperature gradient relevant to past equable climates and, potentially, to future climate change. Using a cloud-system resolving model that explicitly represents moist convection, we conduct idealized experiments on a zonally periodic equatorial β-plane stretching from nearly pole-to-pole and covering roughly one-fifth of Earth’s circumference. To improve the representation of tropical cyclogenesis and mean climate at a horizontal resolution that would otherwise be too coarse for a cloud-system resolving model (15 km), we use the hypohydrostatic rescaling of the equations of motion, also called reduced acceleration in the vertical. The simulations simultaneously represent the Hadley circulation and the intertropical convergence zone, baroclinic waves in mid-latitudes, and a realistic distribution of tropical cyclones (TCs), all without use of a convective parameterization. Using this model, we study the dependence of TCs on the meridional sea surface temperature gradient. When this gradient is significantly reduced, we find a substantial increase in the number of TCs, including a several-fold increase in the strongest storms of Saffir–Simpson categories 4 and 5. This increase occurs as the mid-latitudes become a new active region of TC formation and growth. When the climate warms we also see convergence between the physical properties and genesis locations of tropical and warm-core extra-tropical cyclones. While end-members of these types of storms remain very distinct, a large distribution of cyclones forming in the subtropics and mid-latitudes share properties of the two. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "7003431244;57189992234;24329085500;7004311267;7005453641;35472747700;7005126327;7003620360;13607567200;35614095500;","Comparison of Antarctic polar stratospheric cloud observations by ground-based and space-borne lidar and relevance for chemistry-climate models",2019,"10.5194/acp-19-955-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060626674&doi=10.5194%2facp-19-955-2019&partnerID=40&md5=087f82452e10bf6766790090239af0c4","A comparison of polar stratospheric cloud (PSC) occurrence from 2006 to 2010 is presented, as observed from the ground-based lidar station at McMurdo (Antarctica) and by the satellite-borne CALIOP lidar (Cloud-Aerosol Lidar with Orthogonal Polarization) measuring over McMurdo. McMurdo (Antarctica) is one of the primary lidar stations for aerosol measurements of the NDACC (Network for Detection of Atmospheric Climate Change). The ground-based observations have been classified with an algorithm derived from the recent v2 detection and classification scheme, used to classify PSCs observed by CALIOP. A statistical approach has been used to compare groundbased and satellite-based observations, since point-to-point comparison is often troublesome due to the intrinsic differences in the observation geometries and the imperfect overlap of the observed areas. A comparison of space-borne lidar observations and a selection of simulations obtained from chemistry-climate models (CCMs) has been made by using a series of quantitative diagnostics based on the statistical occurrence of different PSC types. The distribution of PSCs over Antarctica, calculated by several CCMVal-2 and CCMI chemistry-climate models has been compared with the PSC coverage observed by the satellite-borne CALIOP lidar. The use of several diagnostic tools, including the temperature dependence of the PSC occurrences, evidences the merits and flaws of the different models. The diagnostic methods have been defined to overcome (at least partially) the possible differences due to the resolution of the models and to identify differences due to microphysics (e.g., the dependence of PSC occurrence on T -TNAT). A significant temperature bias of most models has been observed, as well as a limited ability to reproduce the longitudinal variations in PSC occurrences observed by CALIOP. In particular, a strong temperature bias has been observed in CCMVal-2 models with a strong impact on PSC formation. The WACCM-CCMI (Whole Atmosphere Community Climate Model - Chemistry-Climate Model Initiative) model compares rather well with the CALIOP observations, although a temperature bias is still present. © Author(s) 2019." "36076994600;7006027075;37031473100;6506424404;57189640729;8586682800;42361807800;12803904100;6603268269;55575158300;","Cloud droplet activation of secondary organic aerosol is mainly controlled by molecular weight, not water solubility",2019,"10.5194/acp-19-941-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060544598&doi=10.5194%2facp-19-941-2019&partnerID=40&md5=f2ab27d5f3bf98e9382e051386775ee8","Aerosol particles strongly influence global climate by modifying the properties of clouds. An accurate assessment of the aerosol impact on climate requires knowledge of the concentration of cloud condensation nuclei (CCN), a subset of aerosol particles that can activate and form cloud droplets in the atmosphere. Atmospheric particles typically consist of a myriad of organic species, which frequently dominate the particle composition. As a result, CCN concentration is often a strong function of the hygroscopicity of organics in the particles. Earlier studies showed organic hygroscopicity increases nearly linearly with oxidation level. Such an increase in hygroscopicity is conventionally attributed to higher water solubility for more oxidized organics. By systematically varying the water content of activating droplets, we show that for the majority of secondary organic aerosols (SOAs), essentially all organics are dissolved at the point of droplet activation. Therefore, for droplet activation, the organic hygroscopicity is not limited by solubility but is dictated mainly by the molecular weight of organic species. Instead of increased water solubility as previously thought, the increase in the organic hygroscopicity with oxidation level is largely because (1) SOAs formed from smaller precursor molecules tend to be more oxidized and have lower average molecular weight and (2) during oxidation, fragmentation reactions reduce average organic molecule weight, leading to increased hygroscopicity. A simple model of organic hygroscopicity based on molecular weight, oxidation level, and volatility is developed, and it successfully reproduces the variation in SOA hygroscopicity with oxidation level observed in the laboratory and field studies. © Author(s) 2019." "11839146600;7101931045;24528488100;56268943500;","Deciphering the contrasting climatic trends between the central Himalaya and Karakoram with 36 years of WRF simulations",2019,"10.1007/s00382-018-4133-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042358359&doi=10.1007%2fs00382-018-4133-3&partnerID=40&md5=8f21f8a92946750ee50c4bd541ba58cf","Glaciers over the central Himalaya have retreated at particularly rapid rates in recent decades, while glacier mass in the Karakoram appears stable. To address the meteorological factors associated with this contrast, 36 years of Climate Forecast System Reanalyses (CFSR) are dynamically downscaled from 1979 to 2015 with the Weather Research and Forecasting (WRF) model over High Mountain Asia at convection permitting grid spacing (6.7 km). In all seasons, CFSR shows an anti-cyclonic warming trend over the majority of High Mountain Asia, but distinctive differences are observed between the central Himalaya and Karakoram in winter and summer. In winter and summer, the central Himalaya has been under the influence of an anti-cyclonic trend, which in summer the downscaling shows has reduced cloud cover, leading to significant warming and reduced snowfall in recent years. Contrastingly, the Karakoram has been near the boundary between large-scale cyclonic and anti-cyclonic trends and has not experienced significant snowfall or temperature changes in winter or summer, despite significant trends in summer of increasing cloud cover and decreasing shortwave radiation. This downscaling does not identify any trends over glaciers in closer neighboring regions to the Karakoram (e.g., Hindu Kush and the western Himalaya) where glaciers have retreated as over the central Himalaya, indicating that there are other factors driving glacier mass balance that this downscaling is unable to capture. While this study does not fully explain the Karakoram anomaly, the identified trends detail important meteorological contributions to the observed differences between central Himalaya and Karakoram glacier evolution in recent decades. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "57201462302;57196496271;7102953444;8934032500;14324150200;6602613489;","Numerical simulation of surface solar radiation over Southern Africa. Part 1: Evaluation of regional and global climate models",2019,"10.1007/s00382-018-4143-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044966769&doi=10.1007%2fs00382-018-4143-1&partnerID=40&md5=0d1ac89e1cc19cc38fab9a5d1af077f2","This study evaluates the performance of climate models in reproducing surface solar radiation (SSR) over Southern Africa (SA) by validating five Regional Climate Models (RCM, including CCLM4, HIRHAM5, RACMO22T, RCA4 and REMO2009) that participated in the Coordinated Regional Downscaling Experiment program over Africa (CORDEX-Africa) along with their ten driving General Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase 5 over SA. The model simulated SSR was thereby compared to reference data from ground-based measurements, satellite-derived products and reanalyses over the period 1990–2005. Results show that (1) the references obtained from satellite retrievals and reanalyses overall overestimate SSR by up to 10 W/m 2 on average when compared to ground-based measurements from the Global Energy Balance Archive, which are located mainly over the eastern part of the southern African continent. (2) Compared to one of the satellite products (Surface Solar Radiation Data Set—Heliosat Edition 2; SARAH-2): GCMs overestimate SSR over SA in terms of their multi-model mean by about 1 W/m 2 (compensation of opposite biases over sub-regions) and 7.5 W/m 2 in austral summer and winter respectively; RCMs driven by GCMs show in their multimodel mean underestimations of SSR in both seasons with Mean Bias Errors (MBEs) of about − 30 W/m 2 in austral summer and about − 14 W/m 2 in winter compared to SARAH-2. This multi-model mean low bias is dominated by the simulations of the CCLM4, with negative biases up to − 76 W/m 2 in summer and − 32 W/m 2 in winter. (3) The discrepancies in the simulated SSR over SA are larger in the RCMs than in the GCMs. (4) In terms of trend during the “brightening” period 1990–2005, both GCMs and RCMs (driven by European Centre for Medium-Range Weather Forecasts Reanalysis ERA-Interim, short as ERAINT and GCMs) simulate an SSR trend of less than 1 W/m 2 per decade. However, variations of SSR trend exist among different references data. (5) For individual RCM models, their SSR bias fields seem rather insensitive with respect to the different lateral forcings provided by ERAINT and various GCMs, in line with previous findings over Europe. (6) Biases in SSR are overall qualitatively consistent with those in total cloud cover. The information obtained in present study is of crucial importance for understanding future climate projections of SSR and for relevant impact studies. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "57193915408;6507157561;7202583200;","Land–atmosphere–ocean interactions in the southeastern Atlantic: interannual variability",2019,"10.1007/s00382-018-4155-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042609209&doi=10.1007%2fs00382-018-4155-x&partnerID=40&md5=d186afa33b6dc12dfa706b01bd7ad624","Land–atmosphere–ocean interactions in the southeastern South Atlantic and their connections to interannual variability are examined using a regional climate model coupled with an intermediate-level ocean model. In austral summer, zonal displacements of the South Atlantic subtropical high (SASH) can induce variations of mixed-layer currents in the Benguela upwelling region through surface wind stress curl anomalies near the Namibian coast, and an eastward shifted SASH is related to the first Pacific–South American mode. When the SASH is meridionally displaced, mixed layer vertically-integrated Ekman transport anomalies are mainly a response to the change of alongshore surface wind stress. The latitudinal shift of the SASH tends to dampen the anomalous alongshore wind by modulating the land-sea thermal contrast, while opposed by oceanic diffusion. Although the position of the SASH is closely linked to the phase of El Niño–Southern Oscillation (ENSO) and the southern annular mode (SAM) in austral summer, an overall relationship between Benguela upwelling strength and ENSO or SAM is absent. During austral winter, variations of the mixed layer Ekman transport in the Benguela upwelling region are connected to the strength of the SASH through its impact on both coastal wind stress curl and alongshore surface wind stress. Compared with austral summer, low-level cloud cover change plays a more important role. Although wintertime sea surface temperature fluctuations in the equatorial Atlantic are strong and may act to influence variability over the northern Benguela area, the surface heat budget analysis suggests that local air-sea interactions dominate. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "36497832500;55689034100;56514334400;56514380000;7404433688;57205739818;","TRMM-Based Optical and Microphysical Features of Precipitating Clouds in Summer Over the Yangtze–Huaihe River Valley, China",2019,"10.1007/s00024-018-1940-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061368337&doi=10.1007%2fs00024-018-1940-8&partnerID=40&md5=88928eeae802581471e133c05b13b65c","The optical and microphysical features of precipitating clouds are key information for studying the satellite-based precipitation estimation, cloud radiative effects, aerosol–cloud–precipitation interactions, cloud and precipitation parameterization in weather and climate models. In this study, 15-year synchronous spectral and radar observations from the TRMM satellite were used to statistically explore the optical and microphysical features of precipitating clouds (PCs), including cloud effective radius (CER), cloud optical thickness (COT), cloud water path (CWP), thermal infrared brightness temperature at channel 4 (TB4) of cloud top, and storm top height (STH) and their relationships with surface rain rates in summer over Yangtze–Huaihe River Valley (YHRV). Results show that the optical and microphysical features of PCs/stratiform PCs/convective PCs vary with geographical locations in summer over YHRV, due to the different ambient meteorological and topographical conditions. Higher CER/COT/CWP/STH and lower TB4 mainly locate at areas of bigger rain rates. For PCs, their spatial distribution of CER is mainly dominated by stratiform PCs, while their spatial distribution of COT/CWP is mainly dominated by convective PCs. Moreover, stratiform precipitation is the dominant form in summer over YHRV and, thus, most PCs present vertical structures of optical and microphysical features as stratiform PCs. Stratiform PCs are usually thicker and contain more water vapor with bigger cloud particles than convective PCs (including deep and shallow convective PCs). In addition, existing shallow convective PCs are associated with lower storm heights and warmer cloud tops. Finally, surface rain rates of PCs (convective/stratiform PCs) increase gradually with the increment of CER/COT/CWP/STH, especially under 5 (15/5) mm/h. Similar relationship between surface rain rates and COT/CWP for shallow convective PCs is also found under 0.75 mm/h. Surface rain rate of PCs (convective/stratiform PCs) with cold cloud tops (TB4 < 247 K) obviously increases as TB4 decreases. Differently, for shallow convective PCs with warmer cloud tops (TB4 > 264 K), surface rain rate usually increases as CER decreases, which suggests that aerosol indirect effects are dominant in lower PCs, because over pollution regions abundant aerosols enter into lower clouds more easily and then suppress the development of shallow convective PCs. © 2018, Springer International Publishing AG, part of Springer Nature." "57205370122;55597199100;55735497000;56021690000;57205589544;","Evaluation of multi-reanalysis solar radiation products using global surface observations",2019,"10.3390/atmos10020042","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060634969&doi=10.3390%2fatmos10020042&partnerID=40&md5=87393e60144ba05213e7e1f38a19da55","Solar radiation incident at the Earth's surface is an essential driver of the energy exchange between the atmosphere and the surface and is also an important input variable in the research on the surface eco-hydrological process. The reanalysis solar radiation dataset is characterized by a long time series and wide spatial coverage and is used in the research of large-scale eco-hydrological processes. Due to certain errors in their production process of the reanalysis of solar radiation products, reanalysis products should be evaluated before application. In this study, three global solar-radiation reanalysis products (ERA-Interim; JRA-55; and NCEP-DOE) in different temporal scales and climate zones were evaluated using surface solar-radiation observations from the National Meteorological Information Center of the China Meteorological Administration (CMA, Beijing, China) and the Global Energy Balance Archive (GEBA, Zürich, Switzerland) from 2000 to 2009. All reanalysis products (ERA-Interim; JRA-55; and NCEP-DOE) overestimated with an annual bias of 14.86 W/m 2 , 22.61 W/m 2 , and 31.85 W/m 2 ; monthly bias of 15.17 W/m 2 , 21.29 W/m 2 , and 36.91 W/m 2 ; and seasonal bias of 15.08 W/m 2 , 21.21 W/m 2 , and 36.69 W/m 2 , respectively. In different Köppen climate zones, the annual solar radiation of ERA-Interim performed best in cold regions with a bias of 10.30 W/m 2 and absolute relative error (ARE) of 8.98%. However, JRA-55 and NCEPDOE showed the best performance in tropical regions with a bias of 20.08 W/m 2 and -0.12 W/m 2 , and ARE of 11.00% and 9.68%, respectively. Overall, through the evaluations across different temporal and spatial scales, the rank of the three reanalysis products in order was the ERA-Interim, JRA-55, and NCEP-DOE. In addition, based on the evaluation, we analyzed the relationship between the error (ARE) of the reanalysis products and cloud cover, aerosol, and water vapor, which significantly influences solar radiation and we found that cloud was the main cause for errors in the three solar radiation reanalysis products. The above can provide a reference for the application and downscaling of the three solar radiation reanalysis products. © 2018 by the authors." "38863214100;6507224579;37861539400;55656837900;6603060770;","Ocean Dynamics and the Inner Edge of the Habitable Zone for Tidally Locked Terrestrial Planets",2019,"10.3847/1538-4357/aaf1a8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062015160&doi=10.3847%2f1538-4357%2faaf1a8&partnerID=40&md5=50d0b8b0b19cc8e69caf952ca562524c","Recent studies have shown that ocean dynamics can have a significant warming effect on the permanent night sides of 1:1 tidally locked terrestrial exoplanets with Earth-like atmospheres and oceans in the middle of the habitable zone. However, the impact of ocean dynamics on the habitable zone boundaries (inner edge and outer edge) is still unknown and represents a major gap in our understanding of this type of planet. Here, we use a coupled atmosphere-ocean global climate model to show that planetary heat transport from the day to nightside is dominated by the ocean at lower stellar fluxes and by the atmosphere near the inner edge of the habitable zone. This decrease in oceanic heat transport at high stellar fluxes is mainly due to weakening of surface wind stress and a decrease in surface shortwave energy deposition. We further show that ocean dynamics have almost no effect on the observational thermal phase curves of planets near the inner edge of the habitable zone. For planets in the habitable zone middle range, ocean dynamics move the hottest spot on the surface eastward from the substellar point. These results suggest that future studies of the inner edge may devote computational resources to atmosphere-only processes such as clouds and radiation. For studies of the middle range and outer edge of the habitable zone, however, fully coupled ocean-atmosphere modeling will be necessary. Note that due to computational resource limitations, only one rotation period (60 Earth days) has been systematically examined in this study; future work with varying rotation periods, as well as other parameters such as atmospheric mass and composition, is required. © 2019. The American Astronomical Society. All rights reserved." "35274839300;57192889179;57195595995;56242212400;7202507292;7005923344;","Dimethylsulfide (DMS) fluxes from permeable coral reef carbonate sediments",2019,"10.1016/j.marchem.2018.11.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056845012&doi=10.1016%2fj.marchem.2018.11.008&partnerID=40&md5=31e51b785c9ef99e28243640bd66c3f6","Dimethylsulfide (DMS) is a biogenic volatile organic compound of high interest as it can influence the Earth's climate by contributing to cloud formation in the atmosphere. Although DMS occurs at high concentrations in coral reef ecosystems, the role of permeable coral reef carbonate sediments as a source and sink of DMS to the surrounding seawater is unknown. Here, we report for the first time fluxes of dissolved DMS from permeable coral reef carbonate sediments over a full diel cycle obtained from benthic chamber deployments on the reef flat of Heron Island, southern Great Barrier Reef. Carbonate coral reef sediments were a substantial net diel source of DMS to the water column (mean 85.4 ± 13.2; range 42.3 ± 5.1 to 114 ± 4.7 nmol m −2 h −1 ), with rates similar to saltmarsh sediments. DMS effluxes were higher in the light under advective porewater flow, suggesting that DMS production in carbonate coral reef sediments is associated with photosynthesis by benthic microalgae. However, DMS effluxes decreased with advection at night, suggesting either greater DMS consumption or less DMS production under dark conditions. Similarly, dimethylsulfoniopropionate (DMSP), which is generally considered the main precursor of DMS, was mainly produced during the day. Net and dark methane (CH 4 ) effluxes negatively correlated with net DMSP and dark DMS fluxes, respectively; suggesting that CH 4 production via methanogenesis could be a sink for DMS and DMSP in carbonate coral reef sediments, especially under dark anoxic conditions. On Heron Island the permeable sands were estimated to contribute from about 22% to 44% of the benthic DMS emitted from the reef to the water column, which could represent an important portion of the yearly sea-to-atmosphere DMS fluxes. Permeable carbonate sediments should be considered further as a source of benthic DMS emitted from coral reefs and the broader continental shelf. © 2018 Elsevier B.V." "26422803600;55324559500;7003510880;56032594900;6603423022;55747201700;57194589938;56531367400;","Nocturnal low-level clouds in the atmospheric boundary layer over southern West Africa: An observation-based analysis of conditions and processes",2019,"10.5194/acp-19-663-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060179487&doi=10.5194%2facp-19-663-2019&partnerID=40&md5=71543be8de559f2afc9a90f73e502c89","During the West African summer monsoon season, extended nocturnal stratiform low-level clouds (LLCs) frequently form in the atmospheric boundary layer over southern West Africa and persist long into the following day affecting the regional climate. A unique data set was gathered within the framework of the Dynamics-Aerosol- Chemistry-Cloud Interactions in West Africa (DACCIWA) project, which allows, for the first time, for an observational analysis of the processes and parameters crucial for LLC formation. In this study, in situ and remote sensing measurements from radiosondes, ceilometer, cloud radar and energy balance stations from a measurement site near Save in Benin are analyzed amongst others for 11 nights. The aim is to study LLC characteristics, the intranight variability of boundary layer conditions and physical processes relevant for LLC formation, as well as to assess the importance of these processes. Based on the dynamic and thermodynamic conditions in the atmospheric boundary layer we distinguish typical nocturnal phases and calculate mean profiles for the individual phases. A stable surface inversion, which forms after sunset, is eroded by differential horizontal cold air advection with the Gulf of Guinea maritime inflow, a cool air mass propagating northwards from the coast in the late afternoon and the evening, and shear-generated turbulence related to a nocturnal low-level jet. The analysis of the contributions to the relative humidity changes before the LLC formation reveals that cooling in the atmospheric boundary layer is crucial to reach saturation, while specific humidity changes play a minor role.We quantify the heat budget terms and find that about 50% of the cooling prior to LLC formation is caused by horizontal cold air advection, roughly 20% by radiative flux divergence and about 22% by sensible heat flux divergence in the presence of a low-level jet. The outcomes of this study contribute to the development of a conceptual model on LLC formation, maintenance and dissolution over southern West Africa. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License." "57212781009;36717393600;8877858700;57191914668;56413849700;26645289600;","Evaluating Cloud Feedbacks and Rapid Responses in the ACCESS Model",2019,"10.1029/2018JD029189","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060127574&doi=10.1029%2f2018JD029189&partnerID=40&md5=31e77929b228026ebbecbc83f8e7a30f","A cloud feedback diagnostic package is implemented in the Australian Community Climate and Earth-System Simulator General Circulation Model, based on the methodology of “cloud radiative kernels.” Using separate increased sea surface temperature and CO 2 experiments, both the “rapid response” cloud contribution to forcing and temperature-mediated cloud feedbacks are analyzed. Under increased temperature and CO 2 changes, temperature-mediated cloud radiative feedback dominates over the rapid response in the final radiative response. Cloud feedback is positive in both long and short wave, with short wave dominating global values. Contributing most to this are low to mid-level clouds, of medium-to-high optical thickness. As a means of illustration of the methodology, a number of key parameters related to clouds, precipitation, and convection that are typically used in “tuning” in the model are modified. These changes result in substantial impacts on the model's current climate, but only modest changes to rapid response and feedbacks occur globally, regionally, and as a function of cloud optical thickness and height. This limited set of experiments shows that cloud adjustments and feedbacks in this model are robust under these changes, lending confidence that both model climate change projections and the conclusions of attribution studies are not overly sensitive to such parameterization tuning. Of course, a considerably larger set of experiments would be needed to demonstrate that feedbacks and rapid response are robust under the wider set of tuning adjustments commonly undertaken. ©2018 Australian Bureau of Meteorology, Commonwealth of Australia." "54400559100;6603400519;6602506180;57190852346;","Spatial Distribution of Melt Season Cloud Radiative Effects Over Greenland: Evaluating Satellite Observations, Reanalyses, and Model Simulations Against In Situ Measurements",2019,"10.1029/2018JD028919","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059559485&doi=10.1029%2f2018JD028919&partnerID=40&md5=e25b55da00223fefdae007d0ec54406e","Arctic clouds can profoundly influence surface radiation and thus surface melt. Over Greenland, these cloud radiative effects (CRE) vary greatly with the diverse topography. To investigate the ability of assorted platforms to reproduce heterogeneous CRE, we evaluate CRE spatial distributions from a satellite product, reanalyses, and a global climate model against estimates from 21 automatic weather stations (AWS). Net CRE estimated from AWS generally decreases with elevation, forming a “warm center” distribution. CRE areal averages from the five large-scale data sets we analyze are all around 10 W/m 2 . Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2), ERA-Interim, and Clouds and the Earth's Radiant Energy System (CERES) CRE estimates agree with AWS and reproduce the warm center distribution. However, the National Center for Atmospheric Research Arctic System Reanalysis (ASR) and the Community Earth System Model Large ENSemble Community Project (LENS) show strong warming in the south and northwest, forming a warm L-shape distribution. Discrepancies are mainly caused by longwave CRE in the accumulation zone. MERRA-2, ERA-Interim, and CERES successfully reproduce cloud fraction and its dominant positive influence on longwave CRE in this region. On the other hand, longwave CRE from ASR and LENS correlates strongly with ice water path instead of with cloud fraction or liquid water path. Moreover, ASR overestimates cloud fraction and LENS underestimates liquid water path substantially, both with limited spatial variability. MERRA-2 best captures the observed interstation changes, captures most of the observed cloud-radiation physics, and largely reproduces both albedo and cloud properties. The warm center CRE spatial distribution indicates that clouds enhance surface melt in the higher accumulation zone and reduce surface melt in the lower ablation zone. ©2018. American Geophysical Union. All Rights Reserved." "6507400558;24921225500;","A New Stochastic Model for the Boundary Layer Clouds and Stratocumulus Phase Transition Regimes: Open Cells, Closed Cells, and Convective Rolls",2019,"10.1029/2018JD029518","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060156521&doi=10.1029%2f2018JD029518&partnerID=40&md5=441a6f05f47598172604d384ced44339","Adequate forecasting, nowcasting, and parameterization of fog and low clouds is still challenging despite being the focus of intensive research for a long time. Stratocumulus clouds have the ability to self-organize into a variety of topological structures, including closed and open convection cells, convection rolls, and scattered cumulus. A lot is known about the large-scale conditions in which shallow clouds and fog develop and decay. However, because of the various complex interactions with the environment, transitions between these various cloud regimes are hard to capture in numerical models. Recent work viewed these cloud regimes as the equilibrium states of phase transition in a stochastic model. Here we build on this idea to propose a new stochastic model based on the lattice particles-Ising model of statistical mechanics, bringing in important improvements by allowing, for example, multiple equilibria and for direct feedback onto the large-scale dynamics. Idealized numerical simulations demonstrate that the new model reproduces qualitatively the observed regimes of stratocumulus when the external forcing is varied. The new model forms a metastable dynamical system where transitions between extreme regimes occur dynamically, that is, within the same numerical simulation, for a large range of fixed parameter values, and sometimes lead to the co-occurrence of mixed states with pockets of closed cells and open cells intercepted by regions of scattered cloudiness, resembling the emergence of convection rolls in nature. This is believed to be a step forward in improving the parameterization of shallow clouds in climate models. ©2018. American Geophysical Union. All Rights Reserved." "55317190600;55720018700;55688930000;57193073844;55802246600;7006705919;","Black Carbon Amplifies Haze Over the North China Plain by Weakening the East Asian Winter Monsoon",2019,"10.1029/2018GL080941","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059870641&doi=10.1029%2f2018GL080941&partnerID=40&md5=c5389cda0a3f9cb3b3d22b05f589136d","Black carbon (BC) has previously been found to intensify haze in China by stabilizing the planetary boundary layer. With ocean, sea ice, and cloud feedbacks included in a global aerosol-climate model, we show that BC emitted from the North China Plain can be transported to the oceans, which in turn changes cloud structure and land-sea thermal contrast. As a result, East Asian winter monsoon wind speeds decrease over the North China Plain. This decrease causes air stagnation that can further intensify haze. Our results suggest that in addition to the local BC-induced interactions between aerosol and the planetary boundary layer, BC can also amplify haze in the North China Plain by weakening East Asian winter monsoon through ocean, sea ice, and cloud feedbacks. It implies that reducing BC emissions could have significant indirect benefits for air quality in the North China Plain. ©2018. American Geophysical Union. All Rights Reserved." "57188628141;35301550500;7004807312;","Estimating Contributions of Sea Ice and Land Snow to Climate Feedback",2019,"10.1029/2018JD029093","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059952325&doi=10.1029%2f2018JD029093&partnerID=40&md5=6573d8a8b4f568f9e34a68bd02e88da9","In this study, we use the National Center for Atmospheric Research Community Earth System Model to investigate the contribution of sea ice and land snow to the climate sensitivity in response to increased atmospheric carbon dioxide content. We focus on the overall effect arising from the presence or absence of sea ice and/or land snow. We analyze our results in terms of the radiative forcing and climate feedback parameter. We find that the presence of sea ice and land snow decreases the climate feedback parameter (and thus increases climate sensitivity). Adjusted radiative forcing from added carbon dioxide is comparatively less sensitive to the presence of sea ice or land snow. The effect of sea ice on the climate feedback parameter decreases as sea ice cover diminishes at higher CO 2 concentration. However, the influence of both sea ice and land snow on the climate feedback parameter remains substantial under the CO 2 concentration range considered here (to eight times preindustrial CO 2 content). Approximately, one quarter of the effect of sea ice and land snow on the climate feedback parameter is a consequence of the effect of these components on longwave feedback that is mainly associated with cloud change. Polar warming in response to added CO 2 is approximately doubled by the presence of sea ice and land snow. Relative to the case in which sea ice and land snow are absent in the model, in response to increased CO 2 concentrations, the presence of sea ice and land snow results in an increase in global mean warming by over 40%. ©2019. American Geophysical Union. All Rights Reserved." "57189755950;","Evaluating Soil Moisture Feedback on Convective Triggering: Roles of Convective and Land-Model Parameterizations",2019,"10.1029/2018JD029326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060153741&doi=10.1029%2f2018JD029326&partnerID=40&md5=2dd48ef4564f890ad4a9e3ebd5023145","Feedbacks between soil moisture and convective precipitation are not well represented in current Earth system models, and can affect projections of drought and heavy-precipitation extremes. To explore the atmospheric and land-surface influences on the initiation (triggering) of daytime deep convection, single-column model experiments were performed using the NCAR Community Earth System Model (CESM1.2), over the U.S. Southern Great Plains. The results indicate that the positive and negative feedback mechanisms found in earlier studies (using simplified boundary-layer models) are robust to large-scale forcing and interactions between boundary-layer turbulence, cloud dynamics, and radiation. However, systematic responses of convective triggering to soil moisture emerged only after switching from a convective available potential energy-based to a convective inhibition energy-based convective parameterization. This suggests that the choice of convective mass-flux closure largely determines the sensitivity of parameterized convective clouds to land-surface state. Errors in land-model parameterizations of evapotranspiration also affect the probability of deep convection, with vegetation (transpiration) playing an important role in linking soil moisture to surface energy partitioning and clouds. Parameterizations that permit the triggering feedback mechanism better predict the statistics of daytime shallow and deep convection, with respect to observations from the Atmospheric Radiation Measurement site in the Southern Great Plains. The results illustrate how errors in the representation of evapotranspiration in land-surface models can propagate through the chain of coupled land-atmosphere processes to affect convective clouds. ©2018. American Geophysical Union. All Rights Reserved." "56340774100;7403046868;6603331306;6602159345;","Seasonal Deuterium Excess Variations of Precipitation at Summit, Greenland, and their Climatological Significance",2019,"10.1029/2018JD028750","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059561786&doi=10.1029%2f2018JD028750&partnerID=40&md5=c5981f70cd6445ac3a2b45693f45b147","The hydrogen and oxygen isotopic composition of ice cores from Summit, Greenland, has provided invaluable information about variations in past climate. However, interpretations of these isotopic data have been made despite a paucity of direct isotopic studies of Summit precipitation. We provide insight to such interpretations by examining the annual cycle of deuterium excess (d-excess) in precipitation samples from Summit and by considering the climatic controls on the annual cycle. Precipitation was collected daily from July 2011 to September 2014 at heights of 1, 2, and 4 m. The isotopic composition of precipitation sampled at 4 m above the snow surface is free of contamination from blowing snow. Precipitation d-excess is high in the summer and low in the winter, a pattern opposite to that found at most high-latitude locations, where summer d-excess is low relative to winter. Low winter d-excess values at Summit can be explained by varying degrees of Rayleigh distillation of moisture sourced from isotopically similar marine sources. However, the observed summer d-excess maximum at Summit is anomalously high compared with other Arctic locations, and we propose that this is due to high d-excess moisture contributed by sublimation of surface snow on the Greenland Ice Sheet. We demonstrate the plausibility of this hypothesis through simple isotopic mass balance calculations, analyses of cloud heights, and back trajectories to identify moisture sources. We show that Rayleigh distillation, sublimation, and the phase of the d-excess annual cycle are all important factors that should be considered in ice core d-excess interpretations. ©2018. American Geophysical Union. All Rights Reserved." "7402859325;36904222100;7402530272;16048686700;","A regional model study of the characteristics and indirect effects of marine primary organic aerosol in springtime over East Asia",2019,"10.1016/j.atmosenv.2018.10.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055101190&doi=10.1016%2fj.atmosenv.2018.10.014&partnerID=40&md5=08c7f4bf039e7de997ebefff3907752a","An online coupled regional chemistry-aerosol-climate model was developed and applied to explore the distribution, evolution and indirect effects of marine primary organic aerosols (MPOA) over East Asia during the period from 12 March to 22 April 2014. Model results were compared with a variety of observations from ground measurement, cruise experiment and satellite retrievals, which demonstrated the model was capable of reproducing reasonably well the major features in meteorological variables, gas species, aerosol components and cloud properties in the western Pacific Ocean in springtime. Active bloom events were observed in the western Pacific Ocean during the study period, with mean surface seawater Chlorophyll a (Chl-a) concentrations up to 10 mg m−3 in the Yellow Sea, East China Sea, Sea of Japan, as well as the ocean northeast of Japan. The mean surface MPOA concentration was simulated to be up to 2.5 μg m−3 in the East China Sea, followed by that in the ocean northeast of Japan, and about 0.5 μg m−3 in the coastal areas of east China. MPOA generally caused increases in the cloud condensation nuclei (CCN), cloud droplet number concentration (CDNC), cloud optical depth (COD) and cloud liquid water path (CLWP), but decrease in the cloud droplet effective radius (CDER). The above changes in cloud properties induced a negative indirect radiative effect (IRE), with the mean values being −5.3 Wm-2, −8.2 Wm-2 and -12.2 Wm-2 over the ocean, East China Sea and the north western Pacific Ocean, which accounted for about 40%, 35% and 51% of the IRE due to all aerosols in these regions, respectively. It was noteworthy that the MPOA induced IRE was −3.6 Wm-2 in east China, accounting for 20% of the IRE by all aerosols and the percentage contribution was about 32% for the whole domain, suggesting its important influence on cloud and radiation during the study period. The sensitivity of MPOA activation to the factors affecting hygroscopicity and surface tension was examined by sensitivity simulations. The indirect effects of MPOA tended to suppress precipitation in most of the domain, with the maximum decrease in the accumulated precipitation up to 50 mm in parts of south China and the East China Sea. In terms of domain average, MPOA accounted for 16%, 22%, 18% of the precipitation reduction due to all aerosols over the land, ocean and the whole domain, respectively, indicating its nonnegligible influence on precipitation over East Asia in springtime 2014. © 2018 Elsevier Ltd" "57147035900;56000854300;6602308024;7004095127;57204338954;","Effects of environmental filters on early establishment of cloud forest trees along elevation gradients: Implications for assisted migration",2019,"10.1016/j.foreco.2018.09.042","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054087732&doi=10.1016%2fj.foreco.2018.09.042&partnerID=40&md5=e7fd939fb0c44d270f0fb648902693bd","Cloud forest tree species are reported to be shifting and retracting their distributional ranges in response to increasing temperatures. However, there is limited information regarding the impact of increasing temperatures on the recruitment of cloud forest trees, a critical phase in population dynamics. Evaluating the establishment of introduced seedlings along an elevation gradient offers an opportunity to assess the influence of environmental change on the early establishment and potential response of cloud forest tree species to assisted migration into higher elevations as a mitigation strategy. We evaluated the early seedling establishment of 3240 seedlings of 12 cloud forest tree species introduced into nine degraded forests subjected to traditional selective logging along an elevation gradient (1250–2517 m a.s.l.) in southern Mexico. We examined (1) how the probability of successful seedling establishment varies along the elevation gradient and (2) how temperature, canopy cover, herbaceous cover and humidity affect seedling survival and growth. Seedling survival, relative growth rates and environmental factors were recorded over a period of two years. Most species displayed high survival (∼90%), and survivorship was most strongly related to canopy cover and temperature. Survival probability increased with canopy cover in five species. Seedling survival and growth decreased with increasing temperature in five species, while the opposite trend was found in two species. Growth rates increased with herbaceous cover in seven species. Humidity had no effect on seedling performance. Our experiment shows that most of the study species have a high probability of seedling survival under canopy cover, even outside the limits of their reported elevational ranges. The results indicate that five of the studied cloud forest species may already benefit from assisted migration to cooler climatic conditions at higher elevations. This study supports the design of management guidelines for assisting the migration of cloud forest tree species with narrow distributions, as a climate change mitigation strategy. © 2018 Elsevier B.V." "56000801700;57194172175;57202361689;6506680987;7101715751;","Changes in vegetation structure during the Pleistocene–Holocene transition in Guanajuato, central Mexico",2019,"10.1007/s00334-018-0685-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048041177&doi=10.1007%2fs00334-018-0685-8&partnerID=40&md5=769b3fff63f44230627c2f219e807024","To investigate the changes in the structure and composition of the vegetation during the Pleistocene–Holocene transition, pollen and macrocharcoal analyses were carried out on samples of sediments taken from a 14.5 m core from Hoya Rincón de Parangueo, a crater lake (maar) in Guanajuato, Mexico. Fossil pollen data from the core suggest that during the last glacial maximum (LGM) the climate in central Mexico was very wet and cold, and the vegetation was open cloud forest, and fires did not occur. During the Pleistocene–Holocene transition, vegetation diversity was high in the study area, but disturbance to vegetation was observed, indicating an open habitat with fewer trees. There was an abrupt change in the composition of the vegetation during the later Holocene, likely signalling a strong change in climate. During the early Holocene the area remained wet, but there was a trend toward drier conditions that became well established at the end of the middle Holocene and into the late Holocene. As a consequence, the structure of the vegetation changed, with more taxa suggesting dryer environments, lasting until the late Holocene, when human disturbance became an important factor affecting vegetation in the area. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "57192709239;36056017400;26434396000;13408817100;7004005379;36183122600;","Comparison of integrated water vapor from GNSS and radiosounding at four GRUAN stations",2019,"10.1016/j.scitotenv.2018.08.192","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052524652&doi=10.1016%2fj.scitotenv.2018.08.192&partnerID=40&md5=3a211770ac5b6a17b770ea33b0bda6d2","Integrated water vapor (IWV) data from Global Navigation Satellite Systems (GNSS) and radiosounding (RS) are compared over four sites (Lindenberg, Ny-Ålesund, Lauder and Sodankylä), which are part of the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN). Both datasets show an excellent agreement, with a high degree of correlation (R2 over 0.98). Dependences of GNSS-RS differences on several variables are studied in detail. Mean bias error (MBE) and standard deviation (SD) increase with IWV, but in relative term, these variables decrease as IWV increases. The dependence on solar zenith angle (SZA) is partially related to the distribution of IWV with SZA, but the increase of SD for low SZA could be associated with errors in the humidity sensor. Large surface pressures worsen performance, which could be due to the fact that low IWV is typically present in high pressure situations. Cloud cover shows a weak influence on the mentioned MBE and SD. The horizontal displacement of radiosondes generally causes SD to increase and MBE to decrease (increase without sign), as it could be expected. The results point out that GNSS measurements are useful to analyze performance to other instruments measuring IWV. © 2018 Elsevier B.V." "7401471372;26029479600;57204365949;","Impacts of a newly-developed aerosol climatology on numerical weather prediction using a global atmospheric forecasting model",2019,"10.1016/j.atmosenv.2018.10.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055312821&doi=10.1016%2fj.atmosenv.2018.10.019&partnerID=40&md5=5c150554003552a5582b09fed7784d31","New four-dimensional aerosol climatology for global weather forecasting model is developed to take aerosol direct effect into account and its impacts on numerical weather prediction are investigated. The proposed aerosol climatology provides the global distribution of monthly-varying species-wise aerosol optical depths with more realistic aerosol vertical profiles. Including aerosol climatology enhances vertical stratification by surface cooling and atmospheric heating through the lower atmosphere by affecting radiation budget. Weakened vertical mixing and reduced surface fluxes related to aerosol loading result in decreased cloud fraction, particularly in the lower atmosphere. Evaluation of medium-range forecasts using the proposed aerosol climatology shows the overall improvement statistically for large-scale variable with reducing their biases, and the alleviation of systematic biases of overestimated light precipitation over the northern hemisphere. © 2018 Elsevier Ltd" "57202774763;15822958100;","The adequacy of stochastically generated climate time series for water resources systems risk and performance assessment",2019,"10.1007/s00477-018-1613-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053765096&doi=10.1007%2fs00477-018-1613-2&partnerID=40&md5=34276f44175efd5591964df7a74b67fe","Stochastic weather generators are designed to produce synthetic sequences that are commonly used for risk discovery, as they would contain rare events that can lead to potentially catastrophic impacts on the environment, or even human lives. These time series are sometimes used as inputs to rainfall-runoff models to simulate the hydrological impacts of these rare events. This paper puts forward a method that evaluates the usefulness of weather generators by assessing how the statistical properties of simulated precipitation, temperatures, and streamflow deviate from those of observations. This is achieved by plotting a large ensemble of (1) synthetic precipitation and temperature time series in a Climate Statistics Space, and (2) hydrological indices using simulated streamflow data in a Risk and Performance Indicators Space. Assessment of weather generator’s performance is based on visual inspection and the Mahalanobis distance between statistics derived from observations and simulations. A case study was carried out on the South Nations watershed in Ontario, Canada, using five different weather generators: two versions of a single-site Weather Generator, two versions of a multi-site Weather Generator (MulGETS) and the K-Nearest Neighbour weather generator (k-nn). Results show that the MulGETS model often outperformed the other weather generators for that particular study area because: (a) the observations were well centered within a point cloud of the synthetically-generated time series in both spaces, and (b) the points generated using MulGETS had a smaller Mahalanobis distance to the observations than those generated with the other weather generators. The k-nn weather generator performed particularly well in simulating temperature variables, but was poor at modelling precipitation and streamflow statistics. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature." "55243717000;56191397900;7401471372;36836680100;","Effects of the convective triggering process in a cumulus parameterization scheme on the diurnal variation of precipitation over East Asia",2019,"10.3390/atmos10010028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060063559&doi=10.3390%2fatmos10010028&partnerID=40&md5=5f2e2af6c6810094627ecc8a73b31cb2","Effects of the convective triggering process in a cumulus parameterization scheme on the diurnal variation of precipitation over East Asia are examined using a regional climate model. Based on a cloud-resolving simulation showing the irrelevance of convective inhibition once convection is initiated and the sensitivity experiments to trigger conditions, the triggering process in the simplified Arakawa-Schubert (SAS) convection scheme is modified to use different convective initiation and termination conditions. The diurnal variation of precipitation frequency with the modified triggering process becomes in phase with the observed one, leading to a delayed afternoon peak in precipitation rate that is in better agreement with the observation. However, the bias in the phase of precipitation intensity is not resolved and the bias of excessive precipitation increases, indicating that adequate representation of not only the triggering process but also other moist convective processes that determine the strength of convection is required for further improvement in the simulation of the diurnal variation of precipitation. © 2019 by the authors." "57188932987;26422498700;35221661700;15047358600;6602136905;","Simulating effects of aerosols on rainfall in southern Africa",2019,"10.1007/s11869-018-0619-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055986107&doi=10.1007%2fs11869-018-0619-8&partnerID=40&md5=3b50c6181826ffd4aa837ea2fb710dd3","Climate-aerosol model ECHAM5-HAM is employed to study effects of aerosol air pollution on rainfall in southern Africa. Aerosols effect the climate through light scattering and absorption, modification of cloud properties, and other indirect effects. The simulation model simulates the global climate on a grid and aerosol emissions from all major economic sectors as provided by the GAINS emission model. Using different model setups, we can separate the effect of aerosol light absorption due to black carbon and other aerosols, that of aerosols interacting with clouds through acting as cloud condensation nuclei and that through the ocean response. This is the first study of its kind to employ aerosol station measurements for model validation. Comparisons are done with previous plentiful studies for south Asia with many similarities in aerosol and rainfall climatology. We conclude that aerosols likely have a weak, negative effect on rainfall with internal variability dominating the simulation results, consistently with observed historical records. Aerosol light absorption does not seem to have a strong impact on rainfall. Meanwhile, the complexity of the problem also leaves uncertainty to the results. Regionally, the results show an opposite pattern of greenhouse gas projections that suggest a wet-get-wetter and dry-get-drier development due to global warming. © 2018, Springer Nature B.V." "54982705800;55879760100;37017289300;55554574300;23990442300;26665602100;55532508600;6507896695;","Implementation of aerosol-cloud interaction within WRF-CHIMERE online coupled model: Evaluation and investigation of the indirect radiative effect from anthropogenic emission reduction on the Benelux Union",2019,"10.3390/atmos10010020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059683079&doi=10.3390%2fatmos10010020&partnerID=40&md5=615d57db4a94ae4b7aecc527452756b2","The indirect effects of aerosol are particularly important over regions where meteorological conditions and aerosol content are favourable to cloud formation. This was observed during the Intensive Cloud Aerosol Measurement Campaign (IMPACT) (European Integrated project on Aerosol Cloud Climate and Air quality Interaction (EUCAARI) project) in the Benelux Union during May 2008. To better understand this cloud formation variability, the indirect effects of aerosol have been included within the WRF-CHIMERE online model. By comparing model results to the aircraft measurements of IMPACT, to surface measurements from EMEP and AIRBASE and to MODIS satellite measurements, we showed that the model is able to simulate the variability and order of magnitude of the observed number of condensation nuclei (CN), even if some differences are identified for specific aerosol size and location. To quantify the impact of the local anthropogenic emissions on cloud formation, a sensitivity study is performed by halving the surface emissions fluxes. It is shown that the indirect radiative effect (IRE) at the surface is positive for both shortwave and longwave with a net warming of +0.99 W/m 2 . In addition, important instantaneous changes are modelled at local scale with up to ±6 °C for temperatures and ±50 mm/day for precipitation. © 2019 by the authors." "57200504486;55470017900;56604019400;6602991061;7003729315;7101707186;6701416358;55393585600;26032229000;","Quantifying the direct radiative effect of absorbing aerosols for numerical weather prediction: A case study",2019,"10.5194/acp-19-205-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059703930&doi=10.5194%2facp-19-205-2019&partnerID=40&md5=e763f3052906191aeee4fa7d8b0a904c","We conceptualize aerosol radiative transfer processes arising from the hypothetical coupling of a global aerosol transport model and a global numerical weather prediction model by applying the US Naval Research Laboratory Navy Aerosol Analysis and Prediction System (NAAPS) and the Navy Global Environmental Model (NAVGEM) meteorological and surface reflectance fields. A unique experimental design during the 2013 NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field mission allowed for collocated airborne sampling by the high spectral resolution Lidar (HSRL), the Airborne Multi-angle SpectroPolarimetric Imager (AirMSPI), up/down shortwave (SW) and infrared (IR) broadband radiometers, as well as NASA A-Train support from the Moderate Resolution Imaging Spectroradiometer (MODIS), to attempt direct aerosol forcing closure. The results demonstrate the sensitivity of modeled fields to aerosol radiative fluxes and heating rates, specifically in the SW, as induced in this event from transported smoke and regional urban aerosols. Limitations are identified with respect to aerosol attribution, vertical distribution, and the choice of optical and surface polarimetric properties, which are discussed within the context of their influence on numerical weather prediction output that is particularly important as the community propels forward towards inline aerosol modeling within global forecast systems. © 2019 Copernicus. All rights reserved." "8385769600;57193272208;55499410800;7006026220;26643509200;","Modeling Atmospheric Age Distribution of Elemental Carbon Using a Regional Age-Resolved Particle Representation Framework",2019,"10.1021/acs.est.8b05895","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059653925&doi=10.1021%2facs.est.8b05895&partnerID=40&md5=1539630560a5c0fdf061b25da2b1c4b2","The aging process of soot particles has significant implications when estimating their impacts on air quality and climate. In this study, the source-oriented University of California at Davis/California Institute of Technology model with externally mixed aerosol representation is expanded to track the age distribution of elemental carbon (EC) in Southeast Texas. EC with the age of 0-3 h (i.e., emitted less than 3 h ago) accounted for ∼70-90% of the total in urban Houston and 20-40% in rural areas of southeast Texas in August 2000. Significant diurnal variations in the mean age of EC are predicted, with higher contributions from fresh particles during the morning and early evening due to increased traffic emission and reduced atmospheric mixing. Spatially, the mean age of EC decreases with proximity to major sources. Ground-level EC with the age >6 h is less than 20% of the first age group over land, and background EC accounts for the majority over the Gulf of Mexico. Differences in EC spatial distribution indicate that age distribution could have regional impact on aerosol optical and hygroscopic properties, and thus potentially affect cloud formation and radiation balance. Appropriately accounting for the differential properties due to age distribution is needed to better evaluate aerosol direct and indirect effects. © 2018 American Chemical Society." "57195958231;8211380400;56594344600;8950138100;56707853300;56403904000;","Drought Impacts on Secondary Organic Aerosol: A Case Study in the Southeast United States",2019,"10.1021/acs.est.8b04842","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058785445&doi=10.1021%2facs.est.8b04842&partnerID=40&md5=22f5f18679e1ef547f4ebe85d9726b91","Secondary organic aerosol (SOA) is a significant component of fine particulate matter, and it has increased during past drought periods in the U.S. Here, we use the Community Multiscale Air Quality (CMAQ) model to characterize the complex effects of drought on SOA through a case study comparing a drought period (June 2011) and a wet period (June 2013) over the southeast U.S. The model simulates a 68% (1.7 μg/m 3 ) higher SOA concentration at the surface during drought and attributes 98% of this increase to biogenic SOA. Through model sensitivity simulations, the SOA increase associated with drought is attributed to 54% from accelerated gas-phase reactions oxidizing volatile organic compounds (VOCs) to SOA, 45% from higher emissions of biogenic VOCs, 18% from enhanced acid-catalyzed production of isoprene SOA in aerosol water due to changing sulfate, 3% from enhanced in-cloud aqueous phase chemistry. Because the higher SOA levels overwhelm the reduced precipitation, there is an increase in wet deposition flux in the drought month which offsets 20% of the total SOA increase. If anthropogenic emissions are held constant, anthropogenic SOA is 51% higher during drought, highlighting the importance of meteorological impacts on chemistry. © 2018 American Chemical Society." "7005528388;7102171439;6603126554;15726427000;36095558300;56219284300;","Temporal and spatial characteristics of short-term cloud feedback on global and local interannual climate fluctuations from A-Train observations",2019,"10.1175/JCLI-D-18-0335.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063006709&doi=10.1175%2fJCLI-D-18-0335.1&partnerID=40&md5=eb257455d14a9c29c65c4e8b6f4c8f9a","Observations from multiple sensors on the NASA Aqua satellite are used to estimate the temporal and spatial variability of short-term cloud responses (CR) and cloud feedbacks λ for different cloud types, with respect to the interannual variability within the A-Train era (July 2002-June 2017). Short-term cloud feedbacks by cloud type are investigated both globally and locally by three different definitions in the literature: 1) the global-mean cloud feedback parameter λGG from regressing the global-mean cloud-induced TOA radiation anomaly ΔRG with the global-mean surface temperature change ΔTGS; 2) the local feedback parameter λLL from regressing the local ΔR with the local surface temperature change ΔTS; and 3) the local feedback parameter λGL from regressing global ΔRG with local ΔTS. Observations show significant temporal variability in the magnitudes and spatial patterns in λGG and λGL, whereas λLL remains essentially time invariant for different cloud types. The global-mean net λGG exhibits a gradual transition from negative to positive in the A-Train era due to a less negative λGG from low clouds and an increased positive λGG from high clouds over the warm pool region associated with the 2015/16 strong El Niño event. Strong temporal variability in λGL is intrinsically linked to its dependence on global ΔRG, and the scaling of λGL with surface temperature change patterns to obtain global feedback λGG does not hold. Despite the shortness of the A-Train record, statistically robust signals can be obtained for different cloud types and regions of interest. © 2019 American Meteorological Society." "57202831187;28367935500;55806727200;","Cloud-Radiative Impact on the Regional Responses of the Midlatitude Jet Streams and Storm Tracks to Global Warming",2019,"10.1029/2018MS001592","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068519842&doi=10.1029%2f2018MS001592&partnerID=40&md5=52e2b11de661e8a627903fdec8bb0bbc","Previous work demonstrated the strong radiative coupling between clouds and the midlatitude circulation. Here we investigate the impact of cloud-radiative changes on the global warming response of the midlatitude jet streams and storm tracks in the North Atlantic, North Pacific, and Southern Hemisphere. To this end, we use the ICOsahedral Nonhydrostatic global atmosphere model in present-day setup and with the cloud-locking method. Sea surface temperatures are prescribed to isolate the circulation response to atmospheric cloud-radiative heating. In the annual mean, cloud-radiative changes contribute one to two thirds to the poleward jet shift in all three ocean basins and support the jet strengthening in the North Atlantic and Southern Hemisphere. Cloud-radiative changes also impact the storm track, but the impact is more diverse across the three ocean basins. The cloud-radiative impact on the North Atlantic and North Pacific jets varies little from season to season in absolute terms, whereas its relative importance changes over the course of the year. In the Southern Hemisphere, cloud-radiative changes strengthen the jet in all seasons, whereas their impact on the jet shift is limited to austral summer and fall. The cloud-radiative impact is largely zonally symmetric and independent of whether global warming is mimicked by a uniform 4 K or spatially varying sea surface temperatures increase. Our results emphasize the importance of cloud-radiative changes for the response of the midlatitude circulation to global warming, indicating that clouds can contribute to uncertainty in model projections of future circulations. ©2019. The Authors." "57190858567;23082420800;8866821900;7006256622;","Cloud radiative feedbacks and El Niño-Southern Oscillation",2019,"10.1175/JCLI-D-18-0842.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068932325&doi=10.1175%2fJCLI-D-18-0842.1&partnerID=40&md5=d0321969c1cbda1a284576f71b076775","Cloud radiative feedbacks are disabled via ""cloud-locking"" in the Community Earth System Model, version 1.2 (CESM1.2), to result in a shift in El Niño-Southern Oscillation (ENSO) periodicity from 2-7 years to decadal time scales. We hypothesize that cloud radiative feedbacks may impact the periodicity in three ways: by 1) modulating heat flux locally into the equatorial Pacific subsurface through negative shortwave cloud feedback on sea surface temperature anomalies (SSTA), 2) damping the persistence of subtropical southeast Pacific SSTA such that the South Pacific meridional mode impacts the duration of ENSO events, or 3) controlling the meridional width of off-equatorial westerly winds, which impacts the periodicity of ENSO by initiating longer Rossby waves. The result of cloud-locking in CESM1.2 contrasts that of another study, which found that cloud-locking in a different global climate model led to decreased ENSO magnitude across all time scales due to a lack of positive longwave feedback on the anomalous Walker circulation. CESM1.2 contains this positive longwave feedback on the anomalous Walker circulation, but either its influence on the surface is decoupled from ocean dynamics or the feedback is only active on interannual time scales. The roles of cloud radiative feedbacks in ENSO in other global climate models are additionally considered. In particular, it is shown that one cannot predict the role of cloud radiative feedbacks in ENSO through a multimodel diagnostic analysis. Instead, they must be directly altered. © 2019 American Meteorological Society." "56539196700;56265041500;56502199700;9249255400;","Strengthened Indian Summer Monsoon Precipitation Susceptibility Linked to Dust-Induced Ice Cloud Modification",2019,"10.1029/2018GL081634","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068753253&doi=10.1029%2f2018GL081634&partnerID=40&md5=888efe0ecb9ad88f0ab98a3f687cd1bf","A growing body of research has underscored the radiative impact of mineral dust in influencing Indian summer monsoon rainfall variability. However, the various aerosol-cloud-precipitation interaction mechanisms remain poorly understood. Here we analyze multisatellite observations to examine dust-induced modification in ice clouds and precipitation susceptibility. We show contrasting dust-induced changes in ice cloud regimes wherein despite a 25% reduction in ice particle radius in thin ice clouds, we find ~40% increase in ice particle radius and ice water path in thick ice clouds resulting in the cloud deepening and subsequently strengthened precipitation susceptibility, under strong updraft regimes. The observed dust-ice cloud-precipitation interactions are supported by a strong correlation between the interannual monsoon rainfall variability and dust frequency. This microphysical-dynamical coupling appears to provide negative feedback to aerosol-cloud interactions, which acts to buffer enhanced aerosol wet scavenging. Our results underscore the importance of incorporating meteorological regime-dependent dust-ice cloud-precipitation interactions in climate simulations. ©2019. American Geophysical Union. All Rights Reserved." "25031430500;36876405100;6701431208;7102696626;30967646900;6602688130;7102976560;6602098362;57210350827;7402207328;7201488063;","High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)",2019,"10.1029/2019GL083978","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069816427&doi=10.1029%2f2019GL083978&partnerID=40&md5=3632e75a55abb7ca5879f8e434dee157","The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long-term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible. ©2019. American Geophysical Union. All Rights Reserved." "57211926026;15751598400;57155431600;8662493200;36559579800;7102266120;8922308700;9132948500;57211721176;","Long-term retrievals of cloud type and fair-weather shallow cumulus events at the ARM SGP site",2019,"10.1175/JTECH-D-18-0215.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075362207&doi=10.1175%2fJTECH-D-18-0215.1&partnerID=40&md5=3a06bc7b7788931a1b712c09c30a3464","A long-term climatology of classified cloud types has been generated for 13 years (1997–2009) over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site for seven cloud categories: low clouds, congestus, deep convection, altocumulus, altostratus, cirrostratus/anvil, and cirrus. The classification was based on the cloud macrophysical quantities of cloud top, cloud base, and physical thickness of cloud layers, as measured by active sensors such as the millimeter-wavelength cloud radar (MMCR) and micropulse lidar (MPL). Climate variability of cloud characteristics has been examined using the 13-yr cloud-type retrieval. Low clouds and cirrus showed distinct diurnal and seasonal cycles. Total cloud occurrence followed the variation of low clouds, with a diurnal peak in early afternoon and a seasonal maximum in late winter. Additionally, further work has been done to identify fair-weather shallow cumulus (FWSC) events for 9 years (2000–08). Periods containing FWSC, a subcategory of clouds classified as low clouds, were produced using cloud fraction information from a total-sky imager and ceilometer. The identified FWSC periods in our study show good agreement with manually identified FWSC, missing only 6 cases out of 70 possible events during the spring to summer seasons (May–August). © 2019 American Meteorological Society." "57201896263;7003543851;30967646900;","Evaluating climate model simulations of the radiative forcing and radiative response at earth's surface",2019,"10.1175/JCLI-D-18-0137.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066485715&doi=10.1175%2fJCLI-D-18-0137.1&partnerID=40&md5=c16793827645302c57f44f25a6520796","We analyze the radiative forcing and radiative response at Earth's surface, where perturbations in the radiation budget regulate the atmospheric hydrological cycle. By applying a radiative kernel-regression technique to CMIP5 climate model simulations where CO2 is instantaneously quadrupled, we evaluate the intermodel spread in surface instantaneous radiative forcing, radiative adjustments to this forcing, and radiative responses to surface warming. The cloud radiative adjustment to CO2 forcing and the temperature-mediated cloud radiative response exhibit significant intermodel spread. In contrast to its counterpart at the top of the atmosphere, the temperature-mediated cloud radiative response at the surface is found to be positive in some models and negative in others. Also, the compensation between the temperature-mediated lapse rate and water vapor radiative responses found in top-of-atmosphere calculations is not present for surface radiative flux changes. Instantaneous radiative forcing at the surface is rarely reported for model simulations; as a result, intermodel differences have not previously been evaluated in global climate models. We demonstrate that the instantaneous radiative forcing is the largest contributor to intermodel spread in effective radiative forcing at the surface. We also find evidence of differences in radiative parameterizations in current models and argue that this is a significant, but largely overlooked, source of bias in climate change simulations. © 2019 American Meteorological Society." "6602960153;7403997708;15722072200;","Empirical values and assumptions in the microphysics of numerical models",2019,"10.1016/j.atmosres.2018.09.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053813032&doi=10.1016%2fj.atmosres.2018.09.010&partnerID=40&md5=50812818b5d4e2df7fae0b176b59b7b5","The microphysics of precipitation has to be parameterized in Earth System Models (ESM), Global Circulation/Climate Models (GCMs), Cloud Resolving Models (CRMs), Regional Climate Models (RCMs), and Numerical Weather Prediction (NWP) models since the relevant physical processes operate at centimeter scale, thus well below the finest model grid size. While more than 20 bulk microphysics schemes have been described in the literature, they all have a number of empirical values and work under a set of reasonable assumptions that treat the problems in a simplified way. This paper discusses these choices in order to present a homogenous account of the physics within the parameterizations, and illustrates how observations can help improve our present understanding of precipitation physics. The Weather and Forecasting Research model (WRF), and the Community Atmosphere Model (CAM) in the Community Earth System Model (CESM) are used as prototypes of full-confidence models. This contribution can also help frame and advance research into the human-induced, ongoing climate change as those parameterizations are instrumental for the appropriate ESM modeling of future climates. © 2018" "56464971600;7004479957;36876405100;7102696626;","Evolution of the Double-ITCZ Bias Through CESM2 Development",2019,"10.1029/2019MS001647","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068537131&doi=10.1029%2f2019MS001647&partnerID=40&md5=79ca64ae0f222f7b7e5f9195eec1d239","The structure of the east Pacific Intertropical Convergence Zone (ITCZ) as simulated in the Community Earth System Model version 2 (CESM2) is greatly improved as compared to its previous version, CESM version 1. Examination of intermediate model versions created as part of the development process for CESM2 shows the improvement in the ITCZ is well correlated with a reduction in the relative warmth of southeast Pacific sea surface temperatures (SSTs) as compared to the broader tropical mean. Cooling SST in this region enhances the zonal SST and surface pressure gradients and reduces the anomalously southward SST gradient present in boreal spring in early version of CESM2. The improvements in southeast Pacific SST are attributed to increases in low cloud cover and the associated shortwave cloud forcing over the southeast. Sensitivity tests using fixed SST simulations demonstrate the increase in cloud cover between two intermediate model versions, 119 and 125, to be driven by removal of the dependence of autoconversion and accretion rates on cloud water variance as well as the removal of a secondary condensation scheme. Both of these changes reduce drizzle rates in warm clouds increasing cloud lifetime and cloud fraction in the stratocumulus to trade cumulus transition region. The improvements in southeast Pacific shortwave cloud forcing and ITCZ climatology persist through subsequent changes to the cloud microphysics parameterizations. Despite improvements in the east Pacific ITCZ, the global mean ITCZ position and Pacific cold tongue bias strength do not exhibit a systematic improvement across the development simulations. ©2019. The Authors." "56293796000;8658386900;7103271625;57198616562;","Updraft constraints on entrainment: Insights from Amazonian deep convection",2019,"10.1175/JAS-D-18-0234.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075578024&doi=10.1175%2fJAS-D-18-0234.1&partnerID=40&md5=2efbe453d00ead609a395a505cfd3bee","Mixing of environmental air into clouds, or entrainment, has been identified as a major contributor to erroneous climate predictions made by modern comprehensive climate and numerical weather prediction models. Despite receiving extensive attention, the ad hoc treatment of this convective-scale process in global models remains poor. On the other hand, while limited-area high-resolution nonhydrostatic models can directly resolve entrainment, their sensitivity to model resolution, especially with the lack of benchmark mass flux observations, limits their applicability. Here, the dataset from the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign focusing on radar retrievals of convective updraft vertical velocities is used with the aid of cloud-resolving model simulations of four deep convective events over the Amazon to provide insights into entrainment. Entrainment and detrainment are diagnosed from the model simulations by applying the mass continuity equation over cloud volumes, in which grid cells are identified by some thresholds of updraft vertical velocity and cloud condensates, and accounting for the sources and sinks of the air mass. Entrainment is then defined as the environmental air intruding into convective cores causing cloud volume to shrink, while detrainment is defined as cloudy grid cells departing the convective core and causing cloud volume to expand. It is found that the diagnosed entrainment from the simulated convective events is strongly correlated to the inverse of the updraft vertical velocities in convective cores, which enables a more robust estimation of the mixing time scale. This highlights the need for improved observational capabilities for sampling updraft velocities across diverse geographic and cloud conditions. Evaluation of a number of assumptions used to represent entrainment in parameterization schemes is also presented, as contrasted against the diagnosed one. © 2019 American Meteorological Society." "7404747615;7102805852;55427995800;","Are Changes in Atmospheric Circulation Important for Black Carbon Aerosol Impacts on Clouds, Precipitation, and Radiation?",2019,"10.1029/2019JD030568","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069807011&doi=10.1029%2f2019JD030568&partnerID=40&md5=3e7bae50546845a5e6fa754b2c5bef60","Black carbon (BC) aerosols strongly absorb solar radiation, but their effective radiative forcing and impacts on regional climate remain highly uncertain owing to strong feedbacks of BC heating on clouds, convection, and precipitation. This study investigates the role of large-scale circulation changes in governing such feedbacks. In the HadGEM3 climate model BC emissions were increased to 10 times present-day values while keeping sea surface temperatures fixed, to assess the rapid adjustments to increased BC absorption. The BC perturbation led to an effective radiative forcing of 2.7 W/m2 and a 0.13-mm/day reduction in global precipitation. There were also large shifts in the spatial distribution of tropical convection, increased low cloud over oceans, and a weakening and poleward shift of midlatitude storm tracks, especially in the Northern Hemisphere. In a parallel experiment, horizontal winds were nudged toward meteorological reanalyses to deliberately suppress circulation responses while allowing changes to the thermodynamic structure of the atmosphere. Surprisingly, BC had approximately the same impact on global-mean radiation and global precipitation in the nudged experiment, even though regional changes in clouds and convection were not fully captured. The results show that large-scale dynamical responses to BC are important for regional impacts but have a limited role in determining the effective radiative forcing and global-mean climate response. The rapid adjustments of clouds, radiation, and global precipitation were primarily a response to increased radiative absorption and atmospheric stability. This implies that short nudged simulations may be sufficient to assess absorbing aerosol impacts on global-mean radiation and precipitation. ©2019 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland." "55355176000;8067118800;56502199700;","The key role of warm rain parameterization in determining the aerosol indirect effect in a global climate model",2019,"10.1175/JCLI-D-18-0789.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068079553&doi=10.1175%2fJCLI-D-18-0789.1&partnerID=40&md5=b5cd92c86b593f08dc4b1d5dea5d04d2","Global climate models (GCMs) have been found to share the common too-frequent bias in the warm rain formation process. In this study, five different autoconversion schemes are incorporated into a single GCM, to systematically evaluate the warm rain formation processes in comparison with satellite observations and investigate their effects on the aerosol indirect effect (AIE). It is found that some schemes generate warm rain less efficiently under polluted conditions in the manner closer to satellite observations, while the others generate warm rain too frequently. Large differences in AIE are found among these schemes. It is remarkable that the schemes with more observation-like warm rain formation processes exhibit larger AIEs that far exceed the uncertainty range reported in IPCC AR5, to an extent that can cancel much of the warming trend in the past century, whereas schemes with too-frequent rain formations yield AIEs that are well bounded by the reported range. The power-law dependence of the autoconversion rate on the cloud droplet number concentration β is found to affect substantially the susceptibility of rain formation to aerosols: the more negative β is, the more difficult it is for rain to be triggered in polluted clouds, leading to larger AIE through substantial contributions from the wet scavenging feedback. The appropriate use of a droplet size threshold can mitigate the effect of a less negative β. The role of the warm rain formation process on AIE in this particular model has broad implications for others that share the too-frequent rain-formation bias. © 2019 American Meteorological Society." "25629070800;56376447200;57191445864;55293780600;7005257933;49261252100;8705999100;55102340600;57193718981;","Contrasting climates at both sides of the Andes in Argentina and Chile",2019,"10.3389/fenvs.2019.00069","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066783626&doi=10.3389%2ffenvs.2019.00069&partnerID=40&md5=c14e1eafeadffa00d09153d6ebb8898d","The prominent Andes cordillera induces significant differences in climates between its eastern and western slopes. These climatic differences are largely reflected by contrasting vegetation and ice coverages but remain poorly documented. This study quantifies the abrupt changes of precipitation and cloud properties at both sides of the Andes south of 20°S by using surface daily precipitation and satellite (CloudSat and MODIS) data during the 2006-2016 period. Results show that the precipitation changes drastically and precipitating clouds can be of very different nature on each side of the Andes. In the tropical Andes (20-25°S), precipitation normally falls from a sole layer of thick stratiform and convective precipitating clouds during the warm semester, but the annual mean accumulation is about 10-100 times larger on the eastern than on the western slopes. A sole layer of low stratus clouds dominates over the Pacific coast, occasionally producing light rains, whereas high, thin, and non-precipitating clouds dominate most of the time over the continent. In the subtropical Andes (25-35°S), annual mean precipitation is similar on both sides, however, it falls from convective and stratiform precipitating clouds in the warm semester on the eastern slopes, and from stratiform precipitating clouds in the cold semester, mostly as frozen particles, on the western slopes. These different features on both slopes denote a climatic transition between the tropics and extratropics. In the extratropical Andes (south of 35°S), stratiform cloud types produces precipitation on both sides during all the year, but the annual mean precipitation and cloud frequency are enhanced on the western slopes and strongly reduced on the eastern slopes of the Andes. Cloud frequencies are higher than in the subtropics and evenly distributed as single- or multi-layers of low, middle and high clouds. Frozen particles become important in precipitating clouds over the mountains and on the lee side. These findings demonstrate the significant influence of the Andes cordillera on the climate all along southwestern South America, and constitute an excellent example of how the simple dependence of climate on latitude can be substantially altered by the topography. © 2019 Viale, Bianchi, Cara, Ruiz, Villalba, Pitte, Masiokas, Rivera and Zalazar." "57191035694;7410070663;8397494800;36095558300;6603613067;56263595100;","Accounting for several infrared radiation processes in climate models",2019,"10.1175/JCLI-D-18-0648.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070113341&doi=10.1175%2fJCLI-D-18-0648.1&partnerID=40&md5=15c55391f6a78e8cd8e9b13b651e567b","Three aspects of longwave (LW) radiation processes are investigated using numerical experiments with the Canadian Atmospheric Global Climate Model version 4.3 (CanAM4.3). These are the overlapping LW and shortwave (SW) radiation, scattering by clouds, and specification of ocean emissivity. For the overlapping of solar and infrared spectra, using a single band scheme was compared against a method directly inputting solar energy. Offline calculations show that for high clouds using the single band can cause an overestimate of the downward LW flux, whereas a method that accounts for input solar energy in the LW yields results that are more accurate. Longwave scattering by clouds traps more infrared energy in the atmosphere and reduces the outgoing radiation to space. Simulations with CanAM4.3 show that cloud LW scattering can enhance the LW cooling rate above the tropopause and reduce it inside the troposphere, resulting in warmer temperatures, especially in the tropics and low latitudes. This implies a larger temperature gradient toward the polar region, which causes a strengthening of the Hadley circulation and shifting of the intertropical convergence zone (ITCZ). The increase in lower tropospheric temperature also affects the lower troposphere water vapor and precipitation. Sensitivity to the specification of ocean emissivity is examined by comparing a broadband scheme dependent on the surface wind and solar zenith angle against one that resolves the wavelength dependence. Experiments with CanAM4.3 show that the two oceanic emissivity schemes can produce over 1 W m-2 seasonal mean difference of the upward flux at the surface. © 2019 American Meteorological Society." "57196437869;8696069500;11939918300;","Climate Change Feedbacks in Aquaplanet Experiments With Explicit and Parametrized Convection for Horizontal Resolutions of 2,525 Up to 5 km",2019,"10.1029/2019MS001677","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068517056&doi=10.1029%2f2019MS001677&partnerID=40&md5=0e6bf97c110c0504d9155f1a20dbaa1c","Earth's equilibrium climate sensitivity (ECS) is the long-term response to doubled atmospheric CO2 and likely between 1.5 and 4.5 K. Conventional general circulation models do not convincingly narrow down this range, and newly developed nonhydrostatic models with relatively fine horizontal resolutions of a few kilometers have thus far delivered diverse results. Here we use the nonhydrostatic ICON model with the physics package normally used for climate simulations at resolutions as fine as 5 km to study the response to a uniform surface warming in an aquaplanet configuration. We apply the model in two setups: one with convection parametrization employed and one with explicit convection. ICON exhibits a negative total feedback independent of convective representation, thus providing a stable climate with an ECS comparable to other general circulation models, though three interesting new results are found. First, ECS varies little across resolution for both setups but runs with explicit convection have systematically lower ECS than the parametrized case, mainly due to more negative tropical clear-sky longwave feedbacks. These are a consequence of a drier mean state of about 6% relative humidity for explicit convection and less midtropospheric moistening with global warming. Second, shortwave feedbacks switch from positive to negative with increasing resolution, originating foremost in the tropics and high latitudes. Third, the model shows no discernible high cloud area feedback (iris effect) in any configuration. It is possible that ICON's climate model parametrizations applied here are less appropriate for cloud resolving scales, and therefore, ongoing developments aim at implementing a more advanced prognostic cloud microphysics scheme. © 2019. The Authors." "57188848315;35098748100;57190214513;56095856700;51461664100;55754495900;56711441000;57214924430;57196548688;55576700800;36815873200;35099345700;7404495164;","Spatiotemporal distributions of cloud parameters and their response to meteorological factors over the Tibetan Plateau during 2003–2015 based on MODIS data",2019,"10.1002/joc.5826","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052815606&doi=10.1002%2fjoc.5826&partnerID=40&md5=37efb47dd3dd8a22b3a6991f117d73fc","The Tibetan Plateau (TP) has important influences on regional and global climate change. Here, we perform an in-depth study of the relationship between cloud parameters and meteorological factors over the TP. The spatiotemporal variations in cloud cover and cloud optical thickness over the TP during the daytime from 2003 to 2015 are analysed using the Aqua-MODIS level 2 atmospheric product data MYD06. Results show that the annual average cloud cover over the TP decreases from the southeast to the northwest. The cloud cover of the western TP is highest in spring and lowest in autumn, while the cloud cover of the eastern TP is higher in spring and summer. The cloud covers in most areas of the TP exceed 30% in spring and summer, and the cloud optical thickness in the southeastern TP exceeds 10 in summer, with substantial cloud cover and cloud optical thickness changes. Compared to other seasons, the cooling effect of the near surface cloud net radiative forcing is greater during daytime in summer, which is likely associated with thick cloud optical thickness or large cloud cover. The results of the analysis of relationships among cloud cover, water vapour and air temperature show that positive correlations exist between cloud cover and water vapour, and that significantly negative correlations exist between cloud cover and air temperature over the TP. Combined with the analysis of variation features in the cloud parameters and meteorological factors, we find that water vapour variations during the daytime over the TP lead to cloud cover changes, which affect the air temperature variations over the TP by the cooling effects of clouds, especially in summer. © 2018 Royal Meteorological Society" "54893098900;36187387300;55885528600;","Evaluating Marine Stratocumulus Clouds in the CNRM-CM6-1 Model Using Short-Term Hindcasts",2019,"10.1029/2018MS001461","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060167483&doi=10.1029%2f2018MS001461&partnerID=40&md5=0310608cc8a1fc36186a496837b0ee52","The representation of stratocumulus by the atmospheric component of the Centre National de Recherches Météorologiques model version 6 (CNRM-CM6-1) is assessed. An Atmospheric Model Intercomparison Project-type simulation is first used to document the main model errors, namely, a large lack of stratocumulus over the eastern part of tropical ocean basins. Short-term hindcasts, following the Transpose-Atmospheric Model Intercomparison Project framework, are then used to better assess the timescales associated with the cloud bias growth and to highlight the processes leading to them. These biases are shown to appear within only a few hours, independently of errors in the large-scale circulation that set up within a few days. Key processes underlying the low-cloud formation are thus mainly local and, to the first order, do not imply any feedback between the model physics and the large-scale dynamics. As a consequence, short-term hindcasts provide a relevant framework to investigate whether the low-cloud underestimate is related to errors in the large-scale state variables or to errors in the model parameterizations. Sensitivity tests highlight that the involved processes arise (1) mostly from misrepresentation of subgrid effects on cloud formation and (2) partly from biases in drying induced by cloud-top entrainment mixing. Improvements in the representation of stratocumulus in the CNRM-CM6-1 model might thus be expected by including a more realistic subgrid-scale temperature and moisture distribution, that would link convective and turbulence processes. Finally, this study confirms the potential of short-term hindcasts, which provide a trustworthy framework to evaluate and develop climate model parameterizations. ©2018. The Authors." "11839267100;6701684534;35331137500;55614596500;57211301037;34882043200;","Analysis of the global microwave polarization data of clouds",2019,"10.1175/JCLI-D-18-0293.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058787935&doi=10.1175%2fJCLI-D-18-0293.1&partnerID=40&md5=cab440d5340bf3fb30a09412fd55dae3","Information about the characteristics of ice particles in clouds is necessary for improving our understanding of the states, processes, and subsequent modeling of clouds and precipitation for numerical weather prediction and climate analysis. Two NASA passive microwave radiometers, the satellite-borne Global Precipitation Measurement (GPM) Microwave Imager (GMI) and the aircraft-borne Conical Scanning Millimeter-Wave Imaging Radiometer (CoSMIR), measure vertically and horizontally polarized microwaves emitted by clouds (including precipitating particles) and Earth's surface below. In this paper, GMI (or CoSMIR) data are analyzed with CloudSat (or aircraft-borne radar) data to find polarized difference (PD) signals not affected by the surface, thereby obtaining the information on ice particles. Statistical analysis of 4 years of GMI and CloudSat data, for the first time, reveals that optically thick clouds contribute positively to GMI PD at 166GHz over all the latitudes and their positive magnitude of 166-GHz GMI PD varies little with latitude. This result suggests that horizontally oriented ice crystals in thick clouds are common from the tropics to high latitudes, which contrasts the result of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) that horizontally oriented ice crystals are rare in optically thin ice clouds. © 2018 American Meteorological Society." "57219013662;6602096831;9535707500;55654205800;55838510804;55653580200;57212031441;","A meteorological discourse on extreme storm events driven by Asian slum emissions",2019,"10.1504/IJEP.2019.103743","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075777750&doi=10.1504%2fIJEP.2019.103743&partnerID=40&md5=0a781d5129716cda03bc5cad90b50009","Increasingly the world over, climate modellers have suggested that local emissions may well affect cyclonic storms. The eastern coast of India, home to mega cities, is routinely battered by such storms over the period October to December. Additionally, these cities house millions of slum dwellers who cook their meals from unseasoned firewood yielding substantial amounts of biomass particles. These particles chemically age within a polluted air mass rendering them active as cloud condensation nuclei (CCN). This first study shows the genesis, progression and evolution of one such tropical disturbance, Hurricane Thane, which was modulated by these transient emissions, devastating the coast of Tamil Nadu on 30 December 2011. We show that auto-conversion rates converting cloud water to rain water are significantly altered by up to 12% with an increase of 20.5% in the cloud water amounts, when these effects are included. © 2019 Inderscience Enterprises Ltd." "57205601401;8670213100;37111900500;9233045100;6507681572;6602844274;6701796418;","Evaluation of CLARA-A2 and ISCCP-H cloud cover climate data records over europe with ECA&D ground-based measurements",2019,"10.3390/rs11020212","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060727573&doi=10.3390%2frs11020212&partnerID=40&md5=2b6af598af818267e650b0306415c1ea","Clouds are of high importance for the climate system but they still remain one of its principal uncertainties. Remote sensing techniques applied to satellite observations have assisted tremendously in the creation of long-term and homogeneous data records; however, satellite data sets need to be validated and compared with other data records, especially ground measurements. In the present study, the spatiotemporal distribution and variability of Total Cloud Cover (TCC) from the Satellite Application Facility on Climate Monitoring (CM SAF) Cloud, Albedo And Surface Radiation dataset from AVHRR data-edition 2 (CLARA-A2) and the International Satellite Cloud Climatology Project H-series (ISCCP-H) is analyzed over Europe. The CLARA-A2 data record has been created using measurements of the Advanced Very High Resolution Radiometer (AVHRR) instrument onboard the polar orbiting NOAA and the EUMETSAT MetOp satellites, whereas the ISCCP-H data were produced by a combination of measurements from geostationary meteorological satellites and the AVHRR instrument on the polar orbiting satellites. An intercomparison of the two data records is performed over their common period, 1984 to 2012. In addition, a comparison of the two satellite data records is made against TCC observations at 22 meteorological stations in Europe, from the European Climate Assessment & Dataset (ECA&D). The results indicate generally larger ISCCP-H TCC with respect to the corresponding CLARA-A2 data, in particular in the Mediterranean. Compared to ECA&D data, both satellite datasets reveal a reasonable performance, with overall mean TCC biases of 2.1 and 5.2% for CLARA-A2 and ISCCP-H, respectively. This, along with the higher correlation coefficients between CLARA-A2 and ECA&D TCC, indicates the better performance of CLARA-A2 TCC data. © 2019 by the authors." "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." "26031036300;","Investigating changes in cloud cover using the long-term record of precipitation extremes",2019,"10.1002/met.1745","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057137586&doi=10.1002%2fmet.1745&partnerID=40&md5=d3f0b54d81c639d50c27d3b69b76fb6a","Clouds are important in a climate system due to their impact on the radiation budget and precipitation. Changes in cloud cover are hard to infer due to lack of reliable long-term cloud datasets. An attempt is made in this study to investigate the changes in cloud cover using the relationship between precipitation extremes and clouds. Heavy precipitation is associated with convective clouds while light precipitation occurs mostly with low clouds. The Global Precipitation and Climatology Project (GPCP) precipitation data are used in this study to relate the changes in heavy and light precipitation with those in convective and low cloud cover, respectively, from the Visible and Infrared Scanner data of the Tropical Rainfall Measuring Mission available from 1998 to 2014. Slopes were derived between changes in precipitation extremes and cloud cover using monthly data. These slopes were applied to long-term trends of precipitation extremes from GPCP data (1979–2016) to infer long-term changes in convective and low cloud cover. Cloud cover derived using this technique shows substantial inter-monthly and inter-annual variability. The results show an increase of about 4.48 ± 1.9% per decade in convective cloud cover over tropical ocean (25 ° S–25 ° N). This is consistent with National Oceanic and Atmospheric Administration (NOAA) High Resolution Infrared Radiometer Sounder (HIRS) observations, which show an increase of about 5.04 ± 2.18% per decade in convective cloud cover over tropical ocean. In the present study an increasing trend of about 5.54 ± 2.07% in convective cloud cover over land (20 °–60 ° N) is also derived, which is comparable to the NOAA HIRS trend of about 6.57 ± 2.53% increase per decade. Decreases of about 3.52 ± 1.69% and 4.26 ± 1.48% per decade in low cloud cover over tropical ocean and northern mid-latitude land, respectively, are reported and are consistent with decreases of about 3.05 ± 1.68% and 5.31 ± 2.22% from NOAA HIRS data over those regions. © 2018 Royal Meteorological Society" "57188736294;8720083500;56587091900;53981601100;56900237500;35219491500;56162305900;7406500188;","Effects of Aerosols on the Precipitation of Convective Clouds: A Case Study in the Yangtze River Delta of China",2019,"10.1029/2018JD029924","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069928444&doi=10.1029%2f2018JD029924&partnerID=40&md5=c225546eb9184931fc8830e18179bf50","Aerosol is a critical factor affecting the atmospheric hydrological cycle and climate change. Acting as cloud condensation nuclei for cloud formation, aerosols have a significant impact on regional precipitation. This study uses the fully coupled chemistry module (Weather Research and Forecasting/Chem) within the Weather Research and Forecasting model to simulate convective cloud precipitation in the Yangtze River Delta of China. To investigate the impact of on precipitation, four numerical experiments are conducted. The base case uses the full emission inventory (which we call the 100% case), and the other three cases are designed based on reduced emissions for different percentages (which we call the 50% case, the 10% case, and the 1% case). Compared to the other cases, the grid point hour maximum precipitation of the 50% case is the largest, which can reach 44.1 mm/hr and has an increase of 5% over the 100% case. The strongest precipitation is delayed by about 1 hr in the 50% case, and precipitation area is increased by 6.5%. This study indicates that the influence of aerosols on regional precipitation is a nonlinear process, with a correlation coefficient of 0.52 (p<0.01) showing a strong positive correlation between cloud condensation nuclei (>250 cm−3, height of 0.5–3 km) and precipitation. Further analysis of the dynamics and microphysical processes of this convective precipitation shows that the 50% case has an area with higher rising velocity and bigger cloud water mixing ratio than the other cases but has a relatively low convective center. The formation of precipitation is mainly influenced by the accretion of snow by rain, but the role of the snow melting into rain cannot be ignored. ©2019. American Geophysical Union. All Rights Reserved." "56001571800;","Characterization of midlatitude cirrus clouds with airborne lidar-investigating an indirect aviation effect",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078096772&partnerID=40&md5=13e598b309886a109dac058293d46195","In view of global warming, science is prompted with the task to investigate all potential impacts on climate. Cirrus clouds that consist of small ice crystals exhibit a considerable climate impact due to their large extent. They lead to high uncertainties in climate prediction, as it is unclear how their impact is modified in a changing climate and by anthropogenic activities. The evermore growing air traffic causes the formation of condensation trails that can persist for long times under suitable conditions and add to the general cirrus cover. Besides this direct effect from aviation, the concept of an indirect effect on natural cirrus clouds has been proposed decades ago. Several modeling studies have investigated this indirect effect, where aircraft exhaust particles contribute to the background aerosol load in the upper troposphere and act as ice nuclei during natural cirrus formation. Yet, it has not been verified in field studies until now. Model estimations of the radiative forcing, delivered contradicting results from no significant effect to a range of-350 mWm-2 to 90mWm-2. These uncertainties stem from the absence of observational evidence that is needed to specify the relevant model scenarios. In this work northern hemisphere midlatitude cirrus clouds are characterized by an airborne lidar and investigated in the context of an indirect effect. Two groups of clouds are identified based on their optical properties. They form two modes in their particle depolarization ratio at δpart = 0.4 and δpart= 0.5. This indicates fundamental differences in the cloud microphysics of both groups. The group with elevated depolarization ratios is associated with the indirect aviation effect. Other possible influences are excluded. This allows first insights into the indirect effect. Clouds in the affected group show lower ice supersaturations, larger particle sizes and lower number concentrations. All this can be interpreted as the traces of heterogeneous freezing due to aircraft exhausts. Whole clouds are affected on a large scale. Their frequent occurrence and their unclear but potentially large climatic impact demands further investigations. From the results of this work, measurement strategies are deduced that will help to gather further observational evidence in future. They should focus on nucleation areas in air traffic and unpolluted regions. © 2019 DLR Deutsches Zentrum fur Luft- und Raumfahrt e.V. - Forschungsberichte. All rights reserved." "56095666600;9245000500;6603058061;","Convection initiation aided by lake-breeze convergence over the Niagara peninsula",2019,"10.1175/MWR-D-19-0123.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075638645&doi=10.1175%2fMWR-D-19-0123.1&partnerID=40&md5=908239fbdd3761596f02c00dace95314","Observations from the 2015 Environment and Climate Change Canada Pan/Parapan American Science Showcase (ECPASS) and real-case, cloud-resolving numerical simulations with the Weather Research and Forecasting (WRF) Model are used to investigate two cases of moist convection forced by lake-breeze convergence over southern Ontario (18 July and 15 August 2015). The two cases shared several characteristics, including high pressure conditions, similar morning soundings, and isolated afternoon convection along a line of lake-breeze convergence between Lakes Erie and Ontario. However, the convection was significantly stronger in the August case, with robustly deeper clouds and larger radar reflectivities than in the July case. Synoptic and mesoscale analyses of these events reveal that the key difference between them was their large-scale forcing. The July event exhibited a combination of strong warm advection and large-scale descent at midlevels (850–650 hPa), which created an inversion layer that capped cloud tops at 4–6 km. The August case exhibited similar features (large-scale descent and warm advection), but these were focused at higher levels (700–400 hPa) and weaker. As a consequence, the convection in the August case was less suppressed at midlevels and ascended deeper (reaching over 8 km). Although the subcloud updraft along the lake-breeze convergence zone was also found to be stronger in the August case, this difference was found to be an effect, rather than a cause, of stronger moist convection within the cloud layer. © 2019 American Meteorological Society." "57199279461;55547120851;57209188201;36660575800;","Investigations of MODIS AOD and cloud properties with CERES sensor based net cloud radiative effect and a NOAA HYSPLIT Model over Bangladesh for the period 2001–2016",2019,"10.1016/j.atmosres.2018.09.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053523846&doi=10.1016%2fj.atmosres.2018.09.001&partnerID=40&md5=8e7582da99b1a2966c7715c418c7dc52","The present study investigates the spatiotemporal characteristics of aerosol optical depth (AOD), cloud properties, and TOA (Top Of Atmosphere) Net Cloud Radiative Effect (Net CRE) using MODIS (Moderate Resolution Imaging Spectroradiometer) Terra and CERES (Clouds and the Earth's Radiant Energy System) products over Bangladesh for the period 2001–2016. This study also explores the backward trajectory using a HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model from the National Oceanic and Atmospheric Administration (NOAA) to discover the origins of air masses. Results show annual values of AOD (0.55), Cloud Fraction (CF, 0.66), CER (Cloud Effective Radius, 14.89), COT (Cloud Optical Thickness, 15.25), CTP (Cloud Top Pressure, 639.17), CTT (Cloud Top Temperature, 262.52), WV (Water Vapor, 4.48), and Net CRE (−13.06) over Bangladesh. A seasonally peak is recorded for AOD (0.64) in MAM while for CF (0.96), CER (17.24), COT (21.12), WV (6.86), and Net CRE (−34.44) the peak is in JJA, and for CTP (884.06) and CTT (284.17) it is in DJF. By monthly the peak is recorded in June for AOD (0.73) and COT (24.86); for CER (17.87), WV (7.26), and Net CRE (−45.38) it is in July; for CF (0.97) it is in July/August; CTP (900.89) and for CTT (285.75) it is in February. Regression analysis shows annual increasing trends for AOD, CF, WV, COT, CTP, and CTT with negative trends for CER and Net CRE. AOD shows increasing trends in all seasons, whereas CF, CER and COT show increasing trends in DJF and MAM only. CTP and CTT show increasing trends in JJA and SON. WV shows an increasing trend in MAM, JJA, and DJF, whereas Net CRE shows an increasing trend in MAM and SON. Relationship study provides a better conclusion of AOD and cloud interaction based on the analysis of positive and negative correlation values over the study region. The backward trajectory indicated that the air masses originated from the Bay of Bengal, India, Nepal, Pakistan, and Iran. This study may be considered as a base document for further study on aerosols over Bangladesh using climate model simulation for the projection period. © 2018 Elsevier B.V." "7202208148;7003663305;","A case study of airmass transformation and cloud formation at Summit, Greenland",2019,"10.1175/JAS-D-19-0056.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075532316&doi=10.1175%2fJAS-D-19-0056.1&partnerID=40&md5=99365fc2590d9289c7de0453c68ab93a","This study investigates cloud formation and transitions in cloud types at Summit, Greenland, during 16–22 September 2010, when a warm, moist air mass was advected to Greenland from lower latitudes. During this period there was a sharp transition between high ice clouds and the formation of a lower stratocumulus deck at Summit. A regional mesoscale model is used to investigate the air masses that form these cloud systems. It is found that the high ice clouds form in originally warm, moist air masses that radiatively cool while being transported to Summit. A sensitivity study removing high ice clouds demonstrates that the primary impact of these clouds at Summit is to reduce cloud liquid water embedded within the ice cloud and water vapor in the boundary layer due to vapor deposition on snow. The mixed-phase stratocumulus clouds form at the base of cold, dry air masses advected from the northwest above 4 km. The net surface radiative fluxes during the stratocumulus period are at least 20 W m-2 larger than during the ice cloud period, indicating that, in seasons other than summer, cold, dry air masses advected to Summit above the boundary layer may radiatively warm the top of the Greenland Ice Sheet more effectively than warm, moist air masses advected from lower latitudes. © 2019 American Meteorological Society." "7404829395;7005528388;56537463000;6602093732;12645767500;8884932600;7006278987;56127418900;7201951829;","Simulation of Remote Sensing of Clouds and Humidity From Space Using a Combined Platform of Radar and Multifrequency Microwave Radiometers",2019,"10.1029/2019EA000580","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070659871&doi=10.1029%2f2019EA000580&partnerID=40&md5=6d4b75a12bb9f6cdc05dfcaf4204fca2","This study presents a simulated simultaneous retrieval of mass mean cloud ice particle effective diameter, ice water content, water vapor, and temperature profiles using a combination of a 94-GHz cloud radar and multifrequency (118, 183, 240, 310, 380, 664, and 850 GHz) millimeter- and submillimeter-wave radiometers from a space platform. The retrieval capabilities and uncertainties of the combined radar and microwave radiometers are quantified. We show that this combined active and passive remote sensing approach with SmallSat technologies addresses a gap in the current state-of-the-art remote sensing measurements of ice cloud properties, especially deriving vertical profiles of ice cloud particle sizes in the atmosphere together with the ambient thermodynamic conditions. Therefore, this new approach can serve as a plausible candidate for future missions that target cloud and precipitation processes to improve weather forecasts and climate predictions. ©2019. The Authors." "57204325320;15725353500;","Exploring Exoplanet Cloud Assumptions in JWST Transmission Spectra",2019,"10.3847/1538-4357/ab3e6d","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073695493&doi=10.3847%2f1538-4357%2fab3e6d&partnerID=40&md5=b370e1289328ce60be5e00b0403cad26","Clouds are ubiquitous in extrasolar planet atmospheres and are critical to our understanding of planetary climate and chemistry. They also represent one of the greater challenges to overcome when trying to interpret transit transmission spectra of exoplanet atmospheres as their presence can inhibit precise constraints on atmospheric composition and thermal properties. In this work, we take a phenomenological approach toward understanding (1) our ability to constrain bulk cloud properties and (2) the impact of clouds on constraining various atmospheric properties as obtained through transmission spectroscopy with the James Webb Space Telescope (JWST). We do this by exploring retrievals of atmospheric and cloud properties for a generic ""hot Jupiter"" as a function of signal-to-noise ratio (S/N), JWST observing modes, and four different cloud parameterizations. We find that most key atmospheric and cloud inferences can be well constrained in the wavelength range (λ = 0.6-11 μm), with NIRCam (λ = 2.5-5 μm) being critical in inferring atmospheric properties and NIRISS + MIRI (λ = 0.6-2.5, 5-11 μm) being necessary for good constraints on cloud parameters. However, constraining the cloud abundance and therefore the total cloud mass requires an observable cloud base in the transit geometry. While higher S/N observations can place tighter constraints on major parameters such as temperature, metallicity, and cloud sedimentation, they are unable to eliminate strong degeneracies among cloud parameters. Our investigation of a generic ""warm Neptune"" with photochemical haze parameterization also shows promising results in constraining atmospheric and haze properties in the cooler temperature regime. © 2019 The American Astronomical Society. All rights reserved." "23394066400;57207619563;9743044300;6701573960;","Long Paddock: Climate risk and grazing information for Australian rangelands and grazing communities",2019,"10.1071/RJ18036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062677945&doi=10.1071%2fRJ18036&partnerID=40&md5=66e7a793fbe27ea9b18da36e2bfdd3db","The Queensland Government's Long Paddock website has been redeveloped on Amazon Web Services cloud computing platform, to provide Australian rangelands and grazing communities (i.e. rural landholders, managers, pastoralists (graziers), researchers, advisors, students, consultants and extension providers) with easier access to seasonal climate and pasture condition information. The website provides free, tailored information and services to support management decisions to maximise productivity, while maintaining the natural resource base. For example, historical rainfall and pasture analyses (i.e. maps, posters and data) have been developed to assist in communicating the risk of multi-year droughts that are a feature of Queensland's highly variable climate. © Australian Rangeland Society 2019 Open Access." "55670345400;6603081424;","Subgrid precipitation properties of mesoscale atmospheric systems represented by modis cloud regimes",2019,"10.1175/JCLI-D-18-0570.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062995204&doi=10.1175%2fJCLI-D-18-0570.1&partnerID=40&md5=baefb44a9ddf2644e5339e992774cac0","The distribution of mesoscale precipitation exhibits diverse patterns: precipitation can be intense but sporadic, or it can be light but widespread. This range of behaviors is a reflection of the different weather systems in the global atmosphere. Using MODIS global cloud regimes as proxies for different atmospheric systems, this study investigates the subgrid precipitation properties within these systems. Taking advantage of the high resolution of Integrated Multisatellite Retrievals for GPM (IMERG; GPM is the Global Precipitation Measurement mission), precipitation values at 0.1° are composited with each cloud regime at 1° grid cells to characterize the regime's spatial subgrid precipitation properties. The results reveal the diversity of the subgrid precipitation behavior of the atmospheric systems. Organized convection is associated with the highest grid-mean precipitation rates and precipitating fraction, although on average only half the grid is precipitating and there is substantial variability between different occurrences. Summer extratropical storms have the next highest precipitation, driven mainly by moderate precipitation rates over large areas. These systems produce more precipitation than isolated convective systems, for which the lower precipitating fractions balance out the high intensities. Most systems produce heavier precipitation in the afternoon than in the morning. The grid-mean precipitation rate is also found to scale with the fraction of precipitation within the grid in a faster-than-linear relationship for most systems. This study elucidates the precipitation properties within cloud regimes, thus advancing our understanding of the precipitation structures of these atmospheric systems. © 2019 American Meteorological Society." "55738939300;57212380079;57188667978;13403507900;","Influence of cloud cover on the relationship between the sky view factor and nocturnal urban heat islands",2019,"10.3354/cr01584","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076508799&doi=10.3354%2fcr01584&partnerID=40&md5=d7ad31b2750748724be1b4b69c3e13f5","Cloud amounts, their spatial distribution, and the sky view factor (SVF) all have effects on the nocturnal upwelling longwave radiation and result in different degrees of urban− rural radiation cooling, which are widely investigated in studies of the urban heat island phenomenon. Currently, most research studies discuss the influence of synoptic conditions and urban geometric morphology on urban heat islands. Here we attempted to determine the influence of cloud cover on the relationship between the SVF and nocturnal urban heat islands by calculating the SVF considering the cloud amount and its distribution. The Adelaide central urban area of South Australia was selected as the study area, and we used urban 3-dimensional building data with a spatial resolution of 1 m and field measurement meteorological data, as well as ceilometer-observed cloud data. We sequentially analyzed the influence of cloud amount on the instantaneous nocturnal urban heat island intensity (UHII), SVF, and SVF–UHII relationship. The SVF–UHII feature space was then constructed to explain the nocturnal urban heat island. The results reveal that there are high negative correlations between the total cloud amount and UHII, while the correlations change with site location. The cloud amount has an effect on the defined SVF. SVFs at all sites gradually increase with the cloud amount, and the SVF differences between various sites decrease with increasing cloud amount. The SVF–UHII feature space can be preliminarily used to explain and simulate the UHII at some sites under different cloud cover conditions, and the mean relative error of the simulated UHII for the example data was 20%. © Inter-Research 2019" "6507017118;6603266501;6603472552;22938899700;","Effect of the North Atlantic Thermohaline Circulation on changes in climatic conditions and river flow in Poland",2019,"10.3390/w11081622","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070324035&doi=10.3390%2fw11081622&partnerID=40&md5=04824f02e01b1f7e8c62d63189601f10","The purpose of this study is to find connections between the North Atlantic Thermohaline Circulation (NA THC), climate elements, such as cloud cover, precipitation, air temperature, sunshine duration, and relative humidity, and flow of rivers in Poland. The intensity of NA THC was characterized by the DG3L index, which was established to assess changes in the amount of heat transported by NA THC along with the transport of water to the Arctic. The paper explains and discusses the mechanism of impact of the NA THC changeability on the elements of the catchment water balance variability. The positive and negative phases of the DG3L index are strongly correlated with the heat anomalies in the upper layer of the North Atlantic waters. The obtained results show that changes of NA THC have significant impact on weather conditions and selected climate elements in Poland. Statistically significant positive correlations were found between the DG3L index and average annual air temperatures, particularly in April, July, and August, while negative between the DG3L index and the total cloud cover. Consequently, in the years with the positive values of the DG3L index, there are favorable conditions for the strong increase in evaporation and evapotranspiration from the ground surface. This has impact on flow of rivers in Poland, which shows considerable regional differences. © 2019 by the authors." "56976231500;21738966900;8887818600;37119437600;55091067600;7003499456;","Regional climate model projections underestimate future warming due to missing plant physiological CO2 response",2019,"10.1088/1748-9326/ab4949","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079717131&doi=10.1088%2f1748-9326%2fab4949&partnerID=40&md5=b4261477201612ca143a0ff98e54ab86","Many countries rely on regional climate model (RCM) projections to quantify the impacts of climate change and to design their adaptation plans accordingly. In several European regions, RCMs project a smaller temperature increase than global climate models (GCMs), which is hypothesised to be due to discrepant representations of topography, cloud processes, or aerosol forcing in RCMs and GCMs. Additionally, RCMs do generally not consider the vegetation response to elevated atmospheric CO2 concentrations; a process which is, however, included in most GCMs. Plants adapt to higher CO2 concentrations by closing their stomata, which can lead to reduced transpiration with concomitant surface warming, in particular, during temperature extremes. Here we show that embedding plant physiological responses to elevated CO2 concentrations in an RCM leads to significantly higher projected extreme temperatures in Europe. Annual maximum temperatures rise additionally by about 0.6 K (0.1 K in southern, 1.2 K in northern Europe) by 2070-2099, explaining about 67% of the stronger annual maximum temperature increase in GCMs compared to RCMs. Missing plant physiological CO2 responses thus strongly contribute to the underestimation of temperature trends in RCMs. The need for robust climate change assessments calls for a comprehensive implementation of this process in RCM land surface schemes. © 2019 The Author(s). Published by IOP Publishing Ltd." "56261144200;56114480400;56728707200;56580354600;57215216824;57215217011;57193847390;","Global climate change: Cyclical nature of natural and permanent nature of man-made processes",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080123462&partnerID=40&md5=bf208a335666452d37c7424d3b2e7ca7","The relevance of the study is due to the trends of global climate change of the Earth, which put human civilization in the conditions of adaptation to the changed parameters of the environment. The main reason for these manifestations is techno-genic human activity associated with the development of industry and agriculture. However, in the process of studying climate change using modern means of scientific and technical observations, the importance of an alternative approach that recognizes the primacy of natural processes occurring on Earth regardless of human activity is proved. The authors of the article relied on the environmental approach to the use of priorities of cyclical nature variability of global climate change, determining the permanent nature of transformation of human techno-genic activity in the preservation of the environment. In this regard, taking into account scientific and technical observations, the article reveals the trends of global climate change; the dominant influence of the cyclical nature of variability on global climate change is established. Based on the study results, the permanent nature of transformation of techno-genic processes of human activity in the conditions of global climate change is substantiated and experimentally proved. © 2019 Khairullina et al." "57209603116;23393212200;","Connecting Direct Effects of CO2 Radiative Forcing to Ocean Heat Uptake and Circulation",2019,"10.1029/2018MS001544","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068753921&doi=10.1029%2f2018MS001544&partnerID=40&md5=0040a8647cd6df98de244a9ad7226218","The ocean's response to direct atmospheric effects of increased carbon dioxide's (CO2) radiative forcing is examined. These direct effects are defined as the climate changes that result from forcing on a fast time scale of about a year, independent of the slower surface warming that the forcing also provokes. To evaluate how these direct effects impact ocean heat uptake and circulation, output of atmospheric general circulation model (GCM) simulations are used to force an ocean GCM with comprehensive boundary conditions. Perturbation simulations with the prescribed response to a quadrupling of atmospheric CO2 include altered surface winds, freshwater fluxes, downwelling shortwave radiation, and downwelling longwave cloud radiative effect. The perturbation simulations show that the intensification and poleward shift of surface winds, particularly in the Southern Ocean, strengthen the shallow overturning circulation in the tropical Pacific and deep overturning in the Atlantic. This, in turn, has a cooling effect on the global ocean at shallow depths. A two-layer energy balance model, designed to capture transient global mean climate change, is adapted to account for the altered ocean heat uptake from direct effects. The direct change in global mean ocean heat uptake is a decrease of about 0.3 W/m2 for quadrupling of CO2, offsetting about 5% of the surface longwave forcing. © 2019. The Authors." "56195639700;","Theoretical understanding of the linear relationship between convective updrafts and cloud-base height for shallow cumulus clouds. Part I: Maritime conditions",2019,"10.1175/JAS-D-18-0323.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072264167&doi=10.1175%2fJAS-D-18-0323.1&partnerID=40&md5=fa97a7f059028f2a7ea171ddf90f78b7","Zheng and Rosenfeld found linear relationships between the convective updrafts and cloud-base height zb using ground-based observations over both land and ocean. The empirical relationships allow for a novel satellite remote sensing technique of inferring the cloud-base updrafts and cloud condensation nuclei concentration, both of which are important for understanding aerosol–cloud–climate interactions but have been notoriously difficult to retrieve from space. In Part I of a two-part study, a theoretical framework is established for understanding this empirical relationship over the ocean. Part II deals with continental cumulus clouds. Using the bulk concept of mixed-layer (ML) model for shallow cumulus, I found that this relationship arises from the conservation law of energetics that requires the radiative flux divergence of an ML to balance surface buoyancy flux. Given a certain ML radiative cooling rate per unit mass Q, a deeper ML (higher zb) undergoes more radiative cooling and requires stronger surface buoyancy flux to balance it, leading to stronger updrafts. The rate with which the updrafts vary with zb is modulated by Q. The cooling rate Q manifests strong resilience to external large-scale forcing that spans a wide range of climatology, allowing the slope of the updrafts–zb relationship to remain nearly invariant. This causes the relationship to manifest linearity. The physical mechanism underlying the resilience of Q to large-scale forcing, such as free-tropospheric moisture and sea surface temperature, is investigated through the lens of the radiative transfer theory (two-stream Schwarzschild equations) and an ML model for shallow cumulus. © 2019 American Meteorological Society." "7410069943;7501757094;7402727736;55754690200;57201829516;56892889800;","Persistent spring shortwave cloud radiative effect and the associated circulations over southeastern China",2019,"10.1175/JCLI-D-18-0385.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066858108&doi=10.1175%2fJCLI-D-18-0385.1&partnerID=40&md5=ebe77b8ae037d50f2602fb75495fd7fc","Clouds strongly modulate regional radiation balance and their evolution is profoundly influenced by circulations. This study uses 2001-16 satellite and reanalysis data together with regional model simulations to investigate the spring shortwave cloud radiative effect (SWCRE) and the associated circulations over southeastern China (SEC). Strong SWCRE, up to -110Wm-2, persists throughout springtime in this region and its spring mean is the largest among the same latitudes of the Northern Hemisphere. SWCRE exhibits pronounced subseasonal variation and is closely associated with persistent regional ascending motion and moisture convergence, which favor large amounts of cloud liquid water and resultant strong SWCRE. Around pentad 12 (late February), SWCRE abruptly increases and afterward remains stable between 22° and 32°N. The thermal and dynamic effects of Tibetan Plateau and westerly jet provide appropriate settings for the maintenance of ascending motion, while water vapor, as cloud water supply, stably comes from the southern flank of the Tibetan Plateau and South China Sea. During pentads 25-36 (early May to late June), SWCRE is further enhanced by the increased water vapor transport caused by the march of East Asian monsoon systems, particularly after the onset of the South China Sea monsoon. After pentad 36, these circulations quickly weaken and the SWCRE decreases accordingly. Individual years with spring strong and weak rainfall are chosen to highlight the importance of the strength of the ascending motion. The simulation broadly reproduced the observed results, although biases exist. Finally, the model biases in SWCRE-circulation associations are discussed. © 2019 American Meteorological Society." "6602206729;6701511324;57201297968;57196393820;15835359300;","Future changes in incident surface solar radiation and contributing factors in India in CMIP5 climate model simulations",2019,"10.1175/JAMC-D-18-0013.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060939788&doi=10.1175%2fJAMC-D-18-0013.1&partnerID=40&md5=682476b4a6f468fe993d684fe6ef8286","To support the planning of future solar energy production in India, forthcoming changes in incoming surface solar radiation and the main physical factors contributing to the change were inferred from simulations performed with 27 global CMIP5 climate models. According to the multimodel-mean response, radiation diminishes by 0.5%-4% by the period 2030-59 (relative to 1971-2000), in tandem with strengthening aerosol and water vapor dimming. The largest reduction is anticipated for northern India. The evolution of incident radiation in the mid- and late twenty-first century depends substantially on the emission scenario. According to the representative concentration pathways RCP2.6 and RCP4.5, solar radiation would gradually recover close to the level that prevailed in the late twentieth century. This results from the peaking of aerosol loading before midcentury while the water vapor content continuously increases somewhat. Conversely, under RCP8.5, incident radiation would still decline, although more slowly than during the early century. This coincides with a substantial increase in atmospheric water vapor content and a modest decrease in aerosol forcing. In cloud forcing, multimodel-mean changes are minor, but divergence among the model simulations is substantial. Moreover, cloud forcing proved to be the factor that correlates most strongly with intermodel differences in the solar radiation response. Multimodel-mean changes in solar radiation are small and would not crucially affect the conditions of solar energy production. Nevertheless, some individual models simulate far more substantial reductions of up to 10%. © 2019 American Meteorological Society." "7102881555;7201888941;7004211601;8716428000;","Keys to differentiating between small- and large-drop icing conditions in continental clouds",2019,"10.1175/JAMC-D-18-0038.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073717117&doi=10.1175%2fJAMC-D-18-0038.1&partnerID=40&md5=615ffab6e8e1ea8d80e81eca8357538a","Using observations from research aircraft flights over the Great Lakes region, synoptic and mesoscale environments that appear to drive a relationship between liquid water content, drop concentration, and drop size are investigated. In particular, conditions that fell within “small drop” and “large drop” regimes are related to cloud and stability profiles, providing insight regarding whether the clouds are tied to the local boundary layer. These findings are supported by analysis of flight data from other parts of North America and used to provide context for several icing incidents and accidents where large-drop icing was noted as a contributing factor. The relationships described for drop size discrimination in continental environments provide clues that can be applied for both human- and model-generated icing forecasts, as well as automated icing algorithms. © 2019 American Meteorological Society." "7003287989;23027838000;6603369413;6508384349;8507259400;","Performance of a simple reanalysis proxy for U.S. cloud-to-ground lightning",2019,"10.1002/joc.6049","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063092262&doi=10.1002%2fjoc.6049&partnerID=40&md5=df3646c573d62d4585e6b530d8bb10da","The product of convective available potential energy (CAPE) and precipitation rate has previously been used as a proxy for cloud-to-ground (CG) lightning flash counts in climate change applications. Here, the ability of this proxy, denoted CP, to represent the climatology and variability of CG lightning flash counts over the contiguous United States (CONUS) during the period 2003–2016 is assessed. CP values computed using the North American Regional Reanalysis are compared with negative and positive polarity CG flash counts from the National Lightning Detection Network. Overall, the proxy performs better on shorter time scales (daily and monthly) than on longer time scales (annual and semi-annual). Proxy performance tends to be worse during the warm season (May–October), when most lightning occurs, and better during the cool season (November–April). The correlation of annually accumulated CONUS CP with CG flash counts is not statistically significant because of poor warm-season performance. Cool season negative CG flash counts are well correlated with CONUS CP values. Positive CG flash counts (∼7% of all CG flashes) are well correlated with annual values of CONUS CP. The relatively strong relations between CP and CG flash counts in some regions and times of the year at daily resolution provide a benchmark for more complex proxies and suggest that proxy-based extended- and long-range prediction of lightning activity may be feasible to the extent that precipitation rate and CAPE can be predicted. © 2019 Royal Meteorological Society" "56814633500;7501439502;55189671700;","Environment and processes for heavy rainfall in the early morning over the Korean peninsula during episodes of cloud clusters associated with mesoscale troughs",2019,"10.2151/jmsj.2019-036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067785631&doi=10.2151%2fjmsj.2019-036&partnerID=40&md5=520385e753c7e262f40d64a119b856eb","An investigation has been carried out using rainfall observation data, an analysis and forecast data by National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) to explain the environment and processes that lead to heavy rainfall in the early morning over the Korean peninsula during episodes of cloud clusters associated with mesoscale troughs (CCMTs). For this study, nine episodes with a maximum hourly rainfall amount in the early morning (i.e., 0300 – 0900 LST) are selected from seventeen heavy-rainfall episodes associated with CCMTs during 2001 – 2011. Case studies on two episodes have revealed that, for both episodes, 1) a low-level trough develops over eastern China and its coastal area during day time; 2) the strong southwesterly band (SWB; an area with wind speeds > 12.5 m s−1) on the pressure level of 925 hPa over the East China Sea, which is located southeast of the trough, strengthens and expands at night time toward the southwestern Korean peninsula; 3) the SWB supplies a large amount of moisture and increases convective instability over the southwestern Korean peninsula with a convection trigger mechanism (i.e., strong horizontal convergence); and 4) heavy rainfall occurs in the early morning over the southwestern Korean peninsula, where the exit region of the SWB is located. A mechanism for the SWB growth is presented. Furthermore, generality of the major results from the two case studies is verified using the results obtained for the composite fields of the nine CCMT episodes. © The Author(s) 2019." "57197786288;24177361900;","Potential vorticity diagnostics to quantify effects of latent heating in extratropical cyclones. Part II: Application to idealized climate change simulations",2019,"10.1175/JAS-D-18-0342.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074975347&doi=10.1175%2fJAS-D-18-0342.1&partnerID=40&md5=b62dcbe6214655874dfbf7a06beade58","It is still debated how enhanced cloud-condensational latent heating (LH) in a warmer and moister climate may affect the dynamics of extratropical cyclones. In this study, a diagnostic method that explicitly quantifies the contribution of LH to the lower-tropospheric cyclonic potential vorticity (PV) anomaly is used to investigate the effects of stronger LH on the dynamics, intensity, and impacts of cyclones in two conceptually different sets of idealized climate change simulations. A first set of regional surrogate climate change simulations of individual moderate to intense Northern Hemisphere cyclones in a spatially homogeneously 4-Kwarmer climate reveals that enhanced LH can largely but not exclusively explain the substantially varying increase in intensity and impacts of most of these cyclones. A second set of idealized aquaplanet GCM simulations demonstrates that the role of enhanced LH becomes multifaceted for large ensembles of cyclones if climate warming is additionally accompanied by changes in the horizontal and vertical temperature structure: Cyclone intensity increases with warming due to the continuous increase in LH, reaches a maximum in climates warmer than present day, and decreases beyond a certain warming once the increase of LH is overcompensated by the counteracting reduction in mean available potential energy. Because of their substantially stronger increase in LH, the most intense cyclones reach their maximum intensity in warmer climates than moderately intense cyclones with weaker LH. This suggests that future projections of the extreme tail of the storm tracks might be particularly sensitive to a correct representation of LH. © 2019 American Meteorological Society." "35847805400;7404700567;7402270607;6701581547;","Climate Change Trends and Impacts on Vegetation Greening Over the Tibetan Plateau",2019,"10.1029/2019JD030481","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069940915&doi=10.1029%2f2019JD030481&partnerID=40&md5=3d0ade9265c2bf91a9ec2b2d24553c63","The Tibetan Plateau (TP) is an ecologically fragile region that is sensitive to climate change. In the context of global climate change, the climate change trends of the TP and the vegetation dynamic response need to be investigated. Based on in situ meteorological data, Satellite Pour l'Observation de la Terre vegetation data, and Moderate Resolution Imaging Spectroradiometer land cover data, a comprehensive analysis was conducted to determine the trends of climate parameters in the TP region at different time scales (long term: 1960–2014; midterm: 1980–2014; short term 1999–2014). A consistent warming trend was observed for different temporal scales, while a warming slowdown was identified during 1999 and 2014. The warming rate was also shown to be much higher in the high-altitude regions (>4,000 m), especially at midterm and short-term time scales. A new cloud-free time series of vegetation index data sets was reconstructed, and the vegetation density showed a general increasing trend along with a warming trend in the TP. The regions showing significant increases accounted for 7.63% of the total Tibetan territory. The major significant greening trend of the TP was mainly caused by climate factors. The reforestation projects may have played a minor role in the vegetation greening in specific regions of the TP. In addition, various vegetation types showed markedly different responses to climate changes. The grassland in semiarid regions, which accounted for 41.9% of the territory of the TP, was identified to be very sensitive to variations in both temperature and precipitation. ©2019. American Geophysical Union. All Rights Reserved." "57210321726;21734034300;36015721000;7004201825;16319351700;57195636034;8445764300;11239699000;56202321100;","Decelerated Greenland Ice Sheet Melt Driven by Positive Summer North Atlantic Oscillation",2019,"10.1029/2019JD030689","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070274979&doi=10.1029%2f2019JD030689&partnerID=40&md5=fbcb2922da404a87b790682de38e1484","The abrupt deceleration of accelerated Greenland Ice Sheet (GrIS) melting since 2013, after a period of acceleration previously noted, is studied here. It is shown that the deceleration of GrIS melting since 2013 is due to the reduction in short-wave solar radiation in the presence of increasing total cloud cover, which is driven by a more persistent positive summer North Atlantic Oscillation on the decadal time scale. By presenting the coherence with the temperature variability at the weather stations in Greenland, which have century-long records, we deduce that the acceleration of GrIS melting during the early 2000s and the subsequent deceleration since 2013 will reoccur frequently on decadal time scales, with the amplitude nearly half of the multidecadal warming trend of the GrIS melt. It can reduce the mass loss from the GrIS on short to medium time scales but is unlikely to halt mass loss related to climate change in the future. This finding highlights the importance of internal climate variability on the mass budget of the GrIS and therefore on predictions of future global sea level change and may help to assist planning for associated social and economic consequences. ©2019. American Geophysical Union. All Rights Reserved." "6603412788;13405561000;8918407000;56823691200;56797095600;57210637310;7004250217;9249656500;10739772300;35997064100;55320961800;7402345338;53871956100;13404531500;7006642995;8653276300;8507223000;","The meteorological research institute Earth system model version 2.0, MRI-ESM2.0: Description and basic evaluation of the physical component",2019,"10.2151/jmsj.2019-051","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068915543&doi=10.2151%2fjmsj.2019-051&partnerID=40&md5=b3bea5677ca641aac2a94871eacb3df5","The new Meteorological Research Institute Earth System Model version 2.0 (MRI-ESM2.0) has been developed based on previous models, MRI-CGCM3 and MRI-ESM1, which participated in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). These models underwent numerous improvements meant for highly accurate climate reproducibility. This paper describes model formulation updates and evaluates basic performance of its physical components. The new model has nominal horizontal resolutions of 100 km for atmosphere and ocean components, similar to the previous models. The atmospheric vertical resolution is 80 layers, which is enhanced from the 48 layers of its predecessor. Accumulation of various improvements concerning clouds, such as a new stratocumulus cloud scheme, led to remarkable reduction in errors in shortwave, longwave, and net radiation at the top of the atmosphere. The resulting errors are sufficiently small compared with those in the CMIP5 models. The improved radiation distribution brings the accurate meridional heat transport required for the ocean and contributes to a reduced surface air temperature (SAT) bias. MRI-ESM2.0 displays realistic reproduction of both mean climate and interannual variability. For instance, the stratospheric quasi-biennial oscillation can now be realistically expressed through the enhanced vertical resolution and introduction of non-orographic gravity wave drag parameterization. For the historical experiment, MRI-ESM2.0 reasonably reproduces global SAT change for recent decades; however, cooling in the 1950s through the 1960s and warming afterward are overestimated compared with observations. MRI-ESM2.0 has been improved in many aspects over the previous models, MRICGCM3 and MRI-ESM1, and is expected to demonstrate superior performance in many experiments planned for CMIP6. © The Author(s) 2019." "57193678066;16403070500;","Regional Climate Response of Middle Eastern, African, and South Asian Monsoon Regions to Explosive Volcanism and ENSO Forcing",2019,"10.1029/2019JD030358","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070726216&doi=10.1029%2f2019JD030358&partnerID=40&md5=af7863a1fc75baee7dd1477f98bb6d03","It is well observed that the monsoon climate experiences substantial climatic changes following explosive volcanism. Likewise, previous studies show that the monsoon climate regimes, especially, the African and South Asian tropical regions, are adversely affected by El Niño-Southern Oscillation (ENSO) events. Hence, studying the sensitivity of the monsoon regions to the effect of these forcing factors, that is, explosive volcanism and volcanic-induced ENSO forcing, is essential for better understanding the driving mechanism and climate variability in these regions. Using observations and a high resolution atmospheric model, effectively at 50- and 25-km grid spacing, this study shows that ENSO and tropical eruptions together weaken the upward branch of Northern Hemisphere (NH) Hadley cell, that is, Intertropical Convergence Zone. This results in a significant decrease of monsoonal precipitation, suggesting severe drought conditions over the NH tropical rain belt regions. The volcanic-induced direct radiative cooling and associated land-sea thermal contrast result in significant warming and drying due to the reduction of clouds over the monsoon regions in boreal summer. The posteruption ENSO circulation also results in warming and drying over NH tropical rain belt regions. This study confirms that the monsoon climate regime responds vigorously to posteruption direct radiative and indirect circulation impacts caused by volcanic-induced ENSO forcing. Hence, quantification of magnitude and spatial pattern of these postvolcanic direct and indirect climatic responses is important for better understanding of climate variability and changes in Asian and African monsoon regions. ©2019. American Geophysical Union. All Rights Reserved." "57192264838;24398842400;6701762451;6602890253;24477694300;18438062100;35430463900;7202057166;57189498750;55683037100;6701834052;6601927317;","Comparison of modeled and measured ice nucleating particle composition in a cirrus cloud",2019,"10.1175/JAS-D-18-0034.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065012850&doi=10.1175%2fJAS-D-18-0034.1&partnerID=40&md5=778af4e4c110a2bf3246a4bc44d931d8","The contribution of heterogeneous ice nucleation to the formation of cirrus cloud ice crystals is still not well quantified. This results in large uncertainties when predicting cirrus radiative effects and their role in Earth's climate system. The goal of this case study is to simulate the composition, and thus activation conditions, of ice nucleating particles (INPs) to evaluate their contribution to heterogeneous cirrus ice formation in relation to homogeneous ice nucleation. For this, the regional model COSMO-Aerosols and Reactive Trace Gases (COSMO-ART) was used to simulate a synoptic cirrus cloud over Texas on 13 April 2011. The simulated INP composition was then compared to measured ice residual particle (IRP) composition from the actual event obtained during the NASA Midlatitude Airborne Cirrus Properties Experiment (MACPEX) aircraft campaign. These IRP measurements indicated that the dominance of heterogeneous ice nucleation was mainly driven by mineral dust with contributions from a variety of other particle types. Applying realistic activation thresholds and concentrations of airborne transported mineral dust and biomass-burning particles, the model implementing the heterogeneous ice nucleation parameterization scheme of Ullrich et al. is able to reproduce the overall dominating ice formation mechanism in contrast to the model simulation with the scheme of Phillips et al. However, the model showed flaws in reproducing the IRP composition. © 2019 American Meteorological Society." "57002856000;6701606453;55170496500;","New Estimates of Aerosol Direct Radiative Effects and Forcing From A-Train Satellite Observations",2019,"10.1029/2019GL083656","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069878574&doi=10.1029%2f2019GL083656&partnerID=40&md5=659936ab7d2ccefdce5d1f795e3057fc","Aerosol direct radiative effects are assessed using multi-sensor observations from the A-Train satellite constellation. By leveraging vertical cloud and aerosol information from CloudSat and CALIPSO, this study reports new global estimates of aerosol radiative effects and the component owing to anthropogenic aerosols. We estimate that the global mean aerosol direct radiative effect is −2.40 W/m2 with an error of ± 0.6 W/m2 owing to uncertainties in aerosol type classification and optical depth retrievals. Anthropogenic direct radiative forcing is assessed using new observation-based aerosol radiative kernels. Anthropogenic aerosols are found to account for 21% of the global radiative effect, or −0.50 ± 0.3 W/m2, mainly from sulfate pollution (−0.54 W/m2) partially offset by absorption from smoke (0.03 W/m2). Uncertainty estimates effectively rule out the possibility that anthropogenic aerosols warm the planet, although strong positive forcing is observed locally where anthropogenic aerosols reside above clouds and bright surfaces. ©2019. American Geophysical Union. All Rights Reserved." "57205337731;55795049300;37119437600;6701847229;7003748648;","The role of hadley circulation and lapse-rate changes for the future European summer climate",2019,"10.1175/JCLI-D-18-0431.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059649241&doi=10.1175%2fJCLI-D-18-0431.1&partnerID=40&md5=1e1b32a1eec914ce15df98e1845ae0ed","By the end of the century, climate projections for southern Europe exhibit an enhanced near-surface summer warming in response to greenhouse gas emissions, which is known as the Mediterranean amplification. Possible causes for this amplified warming signal include a poleward Hadley cell expansion as well as tropospheric lapse-rate changes. In this work, regional climate model (RCM) simulations driven by three different global climate models (GCMs) are performed, representing the RCP8.5 emission scenario. For every downscaled GCM, the climate change signal over Europe is separated into five contributions by modifying the lateral boundary conditions of the RCM. This simulation strategy is related to the pseudo- global warming method. The results show that a poleward expansion of the Hadley cell is of minor importance for the Mediterranean amplification. During summer, the simulated Hadley circulation is weak, and projections show no distinct expansion in the European sector. The north-south contrast in lapse-rate changes is suggested as the most important factor causing the Mediterranean amplification. Lapse-rate changes are projected throughout Europe, but are weaker over the Mediterranean than over northern Europe (around 0.15 vs 0.3Kkm -1 by the end of the century). The weaker lapse-rate changes result in a strong near-surface summer warming over the Mediterranean, since the upper-tropospheric warming is of similar magnitude throughout Europe. The differing lapse-rate changes can be understood as a thermodynamic response to lower-tropospheric humidity contrasts. © 2018 American Meteorological Society." "57205906385;56915435100;57196718266;7006069664;","Inter-comparison and evaluation of mixed-convection schemes in RegCM4 for Indian summer monsoon simulation",2019,"10.1016/j.atmosres.2018.09.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053780923&doi=10.1016%2fj.atmosres.2018.09.002&partnerID=40&md5=ee431cab0a6c23cdbe82c4a237da8423","The present study evaluates the performances of mixed-convection schemes (MCSs) in which different cumulus schemes are activated over the land and ocean separately to simulating the Indian Summer Monsoon (ISM). The regional climate model RegCM4.4 is used and the initial and boundary conditions are derived from the National Centers for Environmental Prediction (NCEP) and Department of Energy (DOE) reanalysis version 2 (NCEP-R2). The NCEP-R2 and the Indian Meteorological Department (IMD) precipitation analysis at 0.25° × 0.25° are used to evaluate the model simulated results. The four cumulus schemes Grell, MIT-Emanuel, Tiedtke, and Kain and Fritsch have been used to setting ten different combinations of MCSs. The MCSs having Tiedtke/Emanuel scheme over the land and the Grell scheme over the ocean (L:Ti_O:Gr; L:Em_O:Gr) are found qualitatively and quantitatively better to simulating the semi-permanent characteristics of the ISM. These MCSs are effectual in predicting seasonal mean precipitation intensity and distribution during the ISM and closer to IMD precipitation analysis than any other MCSs. It is found that the MCS having Grell scheme over the land and ocean, spatial gradient of precipitation is reasonably well when compared to IMD precipitation analysis. The representation of precipitation over the central India is poor in all the MCSs; this is probably due to increased cloud cover in RegCM4 which in turn, leads to reducing surface air temperature over land and thus reduce convective instability in the model simulations. The present study proposes a statistically based screening method to identify the useful MCSs that have reasonable skills. The best performing MCSs examined for normal and deficit monsoon years are used to simulate 15 consecutive monsoon seasons (1982–1996). Simulations of several monsoon years confirm that the two MCSs namely L:Ti_O:Gr and L:Em_O:Gr are suitable to simulate the ISM. © 2018 Elsevier B.V." "18435749300;57208455668;55119602800;57192468922;57075896200;7201972249;57195587405;","Evaluation of tropical cyclone forecasts in the next generation global prediction system",2019,"10.1175/MWR-D-18-0227.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075809238&doi=10.1175%2fMWR-D-18-0227.1&partnerID=40&md5=a7beb9276730ce0a6454263e0f96e25e","A new global model using the GFDL nonhydrostatic Finite-Volume Cubed-Sphere Dynamical Core(FV3) coupled to physical parameterizations from the National Centers for Environmental Prediction'sGlobal Forecast System (NCEP/GFS) was built at GFDL, named fvGFS. The modern dynamical core,FV3, has been selected for the National Oceanic and Atmospheric Administration's Next GenerationGlobal Prediction System (NGGPS) due to its accuracy, adaptability, and computational efficiency, whichbrings a great opportunity for the unification of weather and climate prediction systems. The performanceof tropical cyclone (TC) forecasts in the 13-km fvGFS is evaluated globally based on 363 daily cases of 10-day forecasts in 2015. Track and intensity errors of TCs in fvGFS are compared to those in the operationalGFS. The fvGFS outperforms the GFS in TC intensity prediction for all basins. For TC track prediction,the fvGFS forecasts are substantially better over the northern Atlantic basin and the northern PacificOcean than the GFS forecasts. An updated version of the fvGFS with the GFDL 6-category cloud microphysics scheme is also investigated based on the same 363 cases. With this upgraded microphysicsscheme, fvGFS shows much improvement in TC intensity prediction over the operational GFS. Besidestrack and intensity forecasts, the performance of TC genesis forecast is also compared between the fvGFSand operational GFS. In addition to evaluating the hit/false alarm ratios, a novel method is developed toinvestigate the lengths of TC genesis lead times in the forecasts. Both versions of fvGFS show higher hitratios, lower false alarm ratios, and longer genesis lead times than those of the GFS model in most of theTC basins. © 2019 American Meteorological Society." "25823623500;34972803800;55332289000;7003554893;7202748672;7201398636;55311451800;7005868133;6505903827;14920137300;7003408439;","Convectively coupled equatorial wave simulations using the ECMWF IFS and the NOAA GFS cumulus convection schemes in the NOAA GFS model",2019,"10.1175/MWR-D-19-0195.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075635856&doi=10.1175%2fMWR-D-19-0195.1&partnerID=40&md5=490b69a5357b6f697df0000217f46262","There is a longstanding challenge in numerical weather and climate prediction to accurately model tropical wave variability, including convectively coupled equatorial waves (CCEWs) and the Madden–Julian oscillation. For subseasonal prediction, the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) has been shown to be superior to the NOAA Global Forecast System (GFS) in simulating tropical variability, suggesting that the ECMWF model is better at simulating the interaction between cumulus convection and the large-scale tropical circulation. In this study, we experiment with the cumulus convection scheme of the ECMWF IFS in a research version of the GFS to understand which aspects of the IFS cumulus convection scheme outperform those of the GFS convection scheme in the tropics. We show that the IFS cumulus convection scheme produces significantly different tropical moisture and temperature tendency profiles from those simulated by the GFS convection scheme when it is coupled with other physics schemes in the GFS physics package. We show that a consistent treatment of the interaction between parameterized convective plumes in the GFS planetary boundary layer (PBL) and the IFS convection scheme is required for the GFS to replicate the tropical temperature and moisture profiles simulated by the IFS model. The GFS model with the IFS convection scheme, and the consistent treatment between the convection and PBL schemes, produces much more organized convection in the tropics, and generates tropical waves that propagate more coherently than the GFS in its default configuration due to better simulated interaction between low-level convergence and precipitation. © 2019 American Meteorological Society." "57194380100;6508163320;","Assessment of water harvesting impacts on water conservation by integrating Landsat 7 and CHIRPS datasets in Google Earth Engine platform",2019,"10.3301/ROL.2019.37","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070927312&doi=10.3301%2fROL.2019.37&partnerID=40&md5=b5da2327ce479cd736247c8c20f810ef","Computational capabilities of online cloud-based platforms offered a dramatic increase of the possibilities in the field of geosciences. The novel Google Earth Engine (GEE) platform is among the most powerful and innovative tools, making available both a cloud computational system and wide collections of available satellite remote sensing datasets. This paper presents the GEE analysis of the impacts of Landscape Restoration and Water Harvesting (LRWH) on water conservation potential of a pilot catchment in Tigray Region, Ethiopia. A synthetic Water Conservation Index (WCI) was defined as a function of monthly average Normalized Different Infrared Index (NDII), obtained by Landsat 7 Tier 1 8-Day Composites, and the rainfall amount of June, July and August, calculated from pentadal Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) dataset. Results showed a substantial increase of the WCI after the rainy season for September, with a statistical significance of p<0.01, and for October and November WCI, with a lower statistical significance. Results showed the increase in water conservation obtained through LRWH for Enabered watershed and made clear the new possibilities offered by available ICT structures and cloud-based systems for geosciences, in particular for supporting environmental analysis and land planning in remote and data-scarce areas. © Società Geologica Italiana, Roma 2019." "56003433300;6603431141;35565770000;7004114883;6603140789;","All-sky radiance assimilation of ATMS in HWRF: A demonstration study",2019,"10.1175/MWR-D-17-0337.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060196264&doi=10.1175%2fMWR-D-17-0337.1&partnerID=40&md5=04018f56da26d54066daadc106642e7d","Satellite all-sky radiances from the Advanced Technology Microwave Sounder (ATMS) are assimilated into the Hurricane Weather Research and Forecasting (HWRF) Model using the hybrid Gridpoint Statistical Interpolation analysis system (GSI). To extend the all-sky capability recently developed for global applications to HWRF, some modifications inHWRFand GSI are facilitated. In particular, total condensate is added as a control variable, and six distinct hydrometeor habits are added as state variables in hybrid GSI within HWRF. That is, clear-sky together with cloudy and precipitation-affected satellite pixels are assimilated using the Community Radiative Transfer Model (CRTM) as a forward operator that includes hydrometeor information and Jacobians with respect to hydrometeor variables. A single case study with the 2014 Atlantic storm Hurricane Cristobal is used to demonstrate the methodology of extending the global all-sky capability toHWRFdue toATMSdata availability. Two data assimilation experiments are carried out. One experiment uses the operational configuration and assimilates ATMS radiances under the clear-sky condition, and the other experiment uses the modified HWRF system and assimilates ATMS radiances under the all-sky condition with the inclusion of total condensate update and cycling. Observed and synthetic Geostationary Operational Environmental Satellite (GOES)-13 data along with Global Precipitation Measurement Mission (GPM) Microwave Imager (GMI) data from the two experiments are used to show that the experiment with all-sky ATMS radiances assimilation has cloud signatures that are supported by observations. In contrast, there is lack of clouds in the initial state that led to a noticeable lag of cloud development in the experiment that assimilates clear-sky radiances. © 2018 American Meteorological Society." "56576520000;7004479957;","Simulation of Mesoscale Cellular Convection in Marine Stratocumulus: 2. Nondrizzling Conditions",2019,"10.1029/2018MS001448","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059626816&doi=10.1029%2f2018MS001448&partnerID=40&md5=cf4a7c9326c68dd8901a5e6d4340f09d","This is the second of two large-eddy simulation studies on the mechanisms of mesoscale cellular organization in drizzling (open cells) and nondrizzling marine stratocumulus (closed cells). This study uses a hard nudging approach which maintains fixed horizontal-mean temperature and humidity profiles for a well-mixed boundary layer with a constant boundary layer depth. For the case studied, closed cells develop and broaden by 32 hr to an aspect ratio of 25. Simulations show that the closed-cell mesoscale cellular convection is driven by positive feedback from cloud-induced mesoscale perturbations of longwave radiative cooling. A conceptual model for closed-cell stratocumulus as a mesoscale wavelength hydrodynamic instability in which mesoscale moist and dry anomalies spontaneously grow is presented. In simulations in which long-wavelength sinusoidal moisture anomalies are initially imposed, these anomalies evolve into amplifying closed cells. The cell structure is visualized with a compositing approach based on sorting grid columns by their mesoscale-smoothed total water path. A thermally direct mesoscale circulation pattern develops in the interior of the boundary layer with buoyant mesoscale updrafts, thicker cloud, and a slightly higher capping inversion in the moister columns. There is a mesoscale flow of above-inversion air down the slightly sloping capping inversion from the moist to the dry regions, reinforced by cloud top radiative cooling. This strengthens the mesoscale anomalies by preferentially cooling and drying the already dry regions. The sloping inversion flow is not driven as efficiently if the radiative cooling is artificially horizontally homogenized, partly disrupting this positive feedback and the resulting closed-cell development. ©2018. The Authors." "57195237528;7005231450;","Precipitation Characteristics in the Community Atmosphere Model and Their Dependence on Model Physics and Resolution",2019,"10.1029/2018MS001536","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070297607&doi=10.1029%2f2018MS001536&partnerID=40&md5=ef9d2c8289a7843d08572d0fd9b6c7a7","Precipitation amount (A), frequency (F), intensity (I), and duration (D) are important properties of precipitation, but their estimates are sensitive to data resolution. This study investigates this resolution dependence, and the influences of different model physics, by analyzing simulations by the Community Atmospheric Model (CAM) version 4 (CAM4) and version 5 (CAM5) with varying grid sizes from ~0.25 to 2.0°. Results show that both CAM4 and CAM5 greatly overestimate F and D but underestimate I at all resolutions, despite realistic A. These biases partly result from too much parameterized (convective) precipitation with high F and D but low I. Different cloud microphysics schemes contribute to the precipitation differences between CAM4 and CAM5. The A, F, I, and D of convective and nonconvective precipitation react differently to grid-size decreases, leading to the large decreases in F and D but increases in the I for total precipitation as model resolution increases. This resolution dependence results from the increased probability of precipitation over a larger area (area aggregation effect, which is smaller than in observations) and the varying performance of model physics under changing resolution (model adjustment effect), which roughly enhances the aggregation-induced dependence. Finer grid sizes not only increase resolved precipitation, which has higher intensity and thus improves overall precipitation intensity in CAM, but also reduce the area aggregation effect. Thus, the long-standing drizzling problem in climate models may be mitigated by increasing model resolution and modifying model physics to suppress parameterized convective precipitation and enhance resolved nonconvective precipitation. ©2019. The Authors." "56263595100;57211214177;55487117600;57193857181;38861301900;","Simulation of daily precipitation from CMIP5 in the Qinghai-Tibet Plateau",2019,"10.2151/SOLA.2019-014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072108474&doi=10.2151%2fSOLA.2019-014&partnerID=40&md5=67be29645728548e77e4a5457eccbeef","As the earth's third pole, Qinghai-Tibet Plateau belongs to one of the most sensitive regions to climate change in the world. Based on the observed and the simulated daily precipitation from the Coupled Model Intercomparison Project Phase 5 (CMIP5), we evaluated the simulation performance of daily precipitation from selected CMIP5 models from 1975 to 2005 over the Qinghai-Tibet Plateau. We found that daily precipitation exhibited obvious longrange correlation characteristics using the detrended fluctuation analysis method. The scaling exponents of daily precipitation in summer and autumn are significantly larger than those in spring and winter. MIROC4H with the best performance can reproduce long-range correlation characteristic of daily precipitation series probably because of the higher resolution, which can capture small scale cloud convections. Besides there are seasonal differences in the simulation results among different regions of the Qinghai-Tibet Plateau, simulation effects of all climate models in summer and winter are better than those in spring and autumn. The performance of MIROC4H model works the best in spring. Overall, the scaling exponents of daily precipitation from BCC-CSM1-1-M, CMCC-CM and MIROC4H are close to the observations. CCSM4 and MIROC4H climate models could reproduce the internal dynamics characteristic of daily precipitation in autumn. But for winter, all climate models have exaggerated the scaling value in southeastern Qinghai-Tibet Plateau compared with the observed values. © The Author(s) 2019." "57211890462;55951218500;","Stellar encounters with giant molecular clouds",2019,"10.1093/mnras/stz813","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075257598&doi=10.1093%2fmnras%2fstz813&partnerID=40&md5=7dc41964c7a1e7b8ee8a9948133c46b4","Giant molecular clouds (GMCs) are believed to affect the biospheres of planets as their host star passes through them. We simulate the trajectories of stars and GMCs in the Galaxy and determine how often stars pass through GMCs. We find a strong decreasing dependence with Galactocentric radius, and with the velocity perpendicular to the Galactic plane, Vz. The XY-component of the kinematic heating of stars was shown to not affect the GMC hit rate, unlike the Z-dependence (Vz) implies that stars hit fewer GMCs as they age. GMCs are locations of star formation, therefore we also determine how often stars pass near supernovae. For the supernovae the decrease with Vz is steeper as how fast the star passes through the GMC determines the probability of a supernova encounter. We then integrate a set of Sun-like trajectories to see the implications for the Sun. We find that the Sun hits 1.6 ± 1.3 GMCs per Gyr which results in 1.5 ± 1.1 or (with correction for clustering) 0.8 ± 0.6 supernova closer than 10 pc per Gyr. The different the supernova frequencies are from whether one considers multiple supernovae per GMC crossing (few Myr) as separate events. We then discuss the effect of the GMC hits on the Oort cloud, and the Earth’s climate due to accretion, we also discuss the records of distant supernova. Finally, we determine Galactic Habitable Zone using our model. For the thin disc, we find it to lie between 5.8 and 8.7 kpc and for the thick disc to lie between 4.5 and 7.7 kpc. © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society." "56591585100;55531609200;7004384155;19639722300;","The Response of Tropical Organized Convection to El Niño Warming",2019,"10.1029/2019JD031026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070689266&doi=10.1029%2f2019JD031026&partnerID=40&md5=d60f7de27b6dabb65a0358c7ef02c96c","Convective organization has a large impact on precipitation and feeds back on larger-scale circulations in the tropics. The degree of this convective organization changes with modes of climate variability like the El Niño–Southern Oscillation (ENSO), but because organization is not represented in current climate models, a quantitative assessment of these shifts has not been possible. Here, we construct multidecade satellite climatologies of occurrence of tropical convective organization and its properties and assess changes with ENSO phase. The occurrence of organized deep convection becomes more concentrated, increasing threefold in the eastern and central Pacific during El Niño and decreasing twofold outside of these regions. Both horizontal extent of the cold cloud shield and convective depth increase in regions of positive sea surface temperature anomaly (SSTa); however, the regions of greatest convective deepening are those of large-scale ascent, rather than those of warmest SSTa. Extent decreases with SSTa at a rate of about 20 km/K, while the SSTa dependence of depth is only about 0.2 K/K. We introduce two values to describe convective changes with ENSO more succinctly: (1) an information entropy metric to quantify the clustering of convective system occurrences and (2) a growth metric to quantify deepening relative to spreading over the system lifetime. Finally, with collocated precipitation data, we see that rainfall attributable to convective organization jumps up to 5% with warming. Rain intensity and amount increase for a given system size during El Niño, but a given rain amount may actually fall with higher intensity during La Niña. ©2019. American Geophysical Union. All Rights Reserved." "55918817700;9249656500;10045280300;56823691200;16644465700;10739772300;36623311400;14123161200;57209510065;57213120642;57209513023;57209512338;36871965000;7101928629;7004286908;57203180094;7201350647;","NHM-Chem, the Japan meteorological agency’s regional meteorology – chemistry model: Model evaluations toward the consistent predictions of the chemical, physical, and optical properties of aerosols",2019,"10.2151/JMSJ.2019-020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062050526&doi=10.2151%2fJMSJ.2019-020&partnerID=40&md5=875b6db34a3420b346737ea2ddd2bf7f","The model performance of a regional-scale meteorology-chemistry model (NHM-Chem) has been evaluated for the consistent predictions of the chemical, physical, and optical properties of aerosols. These properties are essentially important for the accurate assessment of air quality and health hazards, contamination of land and ocean ecosystems, and regional climate changes due to aerosol-cloud-radiation interaction processes. Currently, three optional methods are available: the five-category non-equilibrium method, the three-category non-equilibrium method, and the bulk equilibrium method. These three methods are suitable for the predictions of regional climate, air quality, and operational forecasts, respectively. In this paper, the simulated aerosol chemical, physical, and optical properties and their consistency were evaluated using various observation data in East Asia. The simulated mass, size, and deposition of SO42− and NH4 + agreed well with the observations, whereas those of NO3−, sea salt, and dust needed improvement. The simulated surface mass concentration (PM10 and PM2.5) and spherical extinction coefficient agreed well with the observations. The simulated aerosol optical thickness (AOT) and dust extinction coefficient were significantly underestimated. © The Author(s) 2019." "9275539700;27667845700;6506720315;","Simulating the influence of greenhouse gases on the climate of west Africa",2019,"10.22059/poll.2018.266785.526","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071913714&doi=10.22059%2fpoll.2018.266785.526&partnerID=40&md5=202804799d344275d24aecea995516bf","The response of climate to perturbations in GHGs is location dependent. Six experiments: control (CTRL); double CH4; double CO2; double N2O; halved CFC11 and halved CFC12 were carried out to reveal the local area response to different GHGs levels in the atmosphere over West Africa. Double CH4, CO2 and N2O generally induce wetness but they also induce localized dryness at the hilly and mountainous areas of SW Ghana, Central Nigeria, Northern Cameroon and South-eastern Central African Republic. Increase in ground temperature is induced by double GHGs with intensified warming at the north by double CO2. However, patches of cooling are induced at the north. Changes in specific humidity induced by double CO2, CH4 and N2O are similar. Intensified tropical easterly jet is induced by double GHGs. A dipole anomaly of wind with positive at the lower latitude and negative at higher latitude is induced at the northern part of West Africa. Significant reduction in cloud water content is induced from 900 to 400 hPa and 0 and 15oN. © 2019 University of Tehran. All Rights Reserved." "6602835531;7402717381;7003528684;6603588898;24179032200;36139445300;","An Assessment of Surface and Atmospheric Conditions Associated with the Extreme 2014 Wildfire Season in Canada’s Northwest Territories",2019,"10.1080/07055900.2019.1576023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062359776&doi=10.1080%2f07055900.2019.1576023&partnerID=40&md5=2c66332ff9fa77b0a0bb581f2c07687c","Weather and climate are major factors influencing worldwide wildfire activity. This study assesses surface and atmospheric conditions associated with the 2014 extreme wildfires in the Northwest Territories (NWT) of Canada. Hot and dry conditions led to the NWT experiencing the most severe wildfire season in its recorded history. The season included a record number of cloud-to-ground lightning flashes and set a record for area burned. Lightning was the dominant ignition source and accounted for about 95% of the wildfires. Prolonged periods of smoke led to dramatic reductions in visibility, frequent road closures, and reduced air quality resulting in numerous health alerts. Temporal and spatial patterns of lightning characteristics in 2014, derived from Canadian Lightning Detection Network data, were different from those in other years with, for example, far more positive flashes from 0600 to 1200 utc (midnight to 6:00 am local time). The highest fraction of positive cloud-to-ground flashes (43.1%) occurred in the smoke-dominated North Slave region, which was more than in the Dehcho, South Slave, or Sahtu regions. Mid-tropospheric atmospheric circulation over a large region that included the NWT was classified into the six most common summer patterns. Results showed that ridging and ridge displacements occurred more frequently during 2014 although lightning was associated with all circulation patterns. This study has advanced the understanding of the roles of weather, lightning, and mid-tropospheric circulation patterns associated with extreme wildfires in northwestern Canada. © 2019, © 2019 Environment and Climate Change Canada. Published by Informa UK Limited, trading as Taylor & Francis Group." "6506541975;7102954124;35918051100;36498929400;6603887949;","Climate driven changes in timing, composition and size of the Baltic Sea phytoplankton spring bloom",2019,"10.3389/fmars.2019.00482","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069767627&doi=10.3389%2ffmars.2019.00482&partnerID=40&md5=460e39d366d2a633990364993d9c0853","Spring phytoplankton blooms contribute a substantial part to annual production, support pelagic and benthic secondary production and influence biogeochemical cycles in many temperate aquatic systems. Understanding environmental effects on spring bloom dynamics is important for predicting future climate responses and for managing aquatic systems. We analyzed long-term phytoplankton data from one coastal and one offshore station in the Baltic Sea to uncover trends in timing, composition and size of the spring bloom and its correlations to environmental variables. There was a general trend of earlier phytoplankton blooms by 1-2 weeks over the last 20 years, associated with more sunshine and less windy conditions. High water temperatures were associated with earlier blooms of diatoms and dinoflagellates that dominate the spring bloom, and decreased diatom bloom magnitude. Overall bloom timing, however, was buffered by a temperature and ice related shift in composition from early blooming diatoms to later blooming dinoflagellates and the autotrophic ciliate Mesodinium rubrum. Such counteracting responses to climate change highlight the importance of both general and taxon-specific investigations. We hypothesize that the predicted earlier blooms of diatoms and dinoflagellates as a response to the expected temperature increase in the Baltic Sea might also be counteracted by more clouds and stronger winds. A shift from early blooming and fast sedimenting diatoms to later blooming groups of dinoflagellates and M. rubrum at higher temperatures during the spring period is expected to increase energy transfers to pelagic secondary production and decrease spring bloom inputs to the benthic system, resulting in lower benthic production and reduced oxygen consumption. © 2019 Hjerne, Hajdu, Larsson, Downing and Winder." "14052002000;7005456532;7202408584;7103197356;15071768600;6701620591;","Improving the McClear model estimating the downwelling solar radiation at ground level in cloud-free conditions - McClear-v3",2019,"10.1127/metz/2019/0946","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069036189&doi=10.1127%2fmetz%2f2019%2f0946&partnerID=40&md5=8553ff93e35ba30afe02c311b500e695","The fast McClear clear-sky model estimates the downwelling shortwave direct and diffuse irradiances received at ground level under cloud-free conditions. Several improvements are presented. They focus on the modeling of changes in irradiances with the solar zenithal angle and on a better exploitation of the aerosol properties offered by the Copernicus Atmosphere Monitoring Service (CAMS). Irradiances from this new version McClear-v3 were compared to 1 min measurements made in cloud-free conditions at 11 stations belonging to the Baseline Surface Radiation Network and being located in various climates. The correlation coefficient ranges between 0.982 and 0.999 for the global irradiance. The bias is positive (overestimation) and ranges between 1 W m−2 (0.1 % of the mean observed irradiance) and 20 W m−2 (3.2 %), with the exception of Barrow in Alaska (18 W m−2). The standard deviation ranges between 16 W m−2 (2.3 %) and 30 W m−2 (3.8 %). The correlation coefficient for the direct irradiance ranges between 0.902 and 0.995. As expected, since the direct in McClear does not comprise any circumsolar contribution, the bias is negative (underestimation) and ranges between 49 W m−2 (7.7 %) and 5 W m−2 (0.7 %), with two exceptions: Sede Boqer (79 W m−2) and Brasilia (13 W m−2). The standard deviation is comprised between 34 W m−2 (5.3 %) and 69 W m−2 (10.7 %). These results are similar to those obtained with McClear version 2. Compared to the latter, McClear-v3 removes several artifacts and its estimates are continuous in space and time. © 2019 The authors" "55154357500;55995253900;","Precipitation, Humidity and Cloudiness in Podgorica (Montenegro) during the Period 1951–2018",2019,"10.5937/gp23-23582","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087300100&doi=10.5937%2fgp23-23582&partnerID=40&md5=68e80b5c7e2e7353a9ae94e627691529","This paper presents the results of a trend analysis of three climate elements: precipitation, cloudiness and humidity. Almost the entire period of instrumental measurements (precipitation and humidity) and visual observations (cloudiness) are covered. In the observed 68-year period (1951–2018), the trend of annual and seasonal precipitation amounts is insignificant. Though, there is a significant decrease in the number of days with precipitation ≥ 1 mm, which implies a movement towards more arid conditions. On the other hand, the number of days with extreme rainfall ≥ 40 and 50 mm is increasing. In Podgorica, the annual statistics of days with snow cover decreases as well. There is also a decrease in the relative humidity and cloudiness, and with both elements the trend is insignificant only in the autumn season. The results of the trend calculation show that the number of gloomy days is more intensively reduced than the number of increasing bright days. In general, the results of the research show that the climate of Podgorica tends to be more arid with more extreme weather events. The climate variations happening in this city are, to small amount, caused by the urbanization process. Podgorica has the character of an urban heat island in a cooler environment, with an average annual intensity of about 0.7°C and the highest in winter (about 0.8°C). The most symptomatic indicator of urbanization is temperature, but anthropogenic heat production in the city (asphalt, constructions, increase of aerosols, etc.) also affects other climate elements. Compared to the non-urban environment, Podgorica has a higher annual rainfall of 100 mm and a lower humidity of 3%, while this difference is not noticeable in the overall cloudiness. © 2020" "6603482124;6506664475;","Meteorological conditions on Kaffiøyra (NW Spitsbergen) in 2013–2017 and their connection with atmospheric circulation and sea ice extent",2019,"10.24425/ppr.2019.129670","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074888483&doi=10.24425%2fppr.2019.129670&partnerID=40&md5=5d9d83a361b88dec72adbb0927066616","This article comprises an analysis of the variability of meteorological conditions on Kaffiøyra (NW Spitsbergen, Svalbard) in 2013–2017 in connection with atmospheric circulation and the extent of sea ice. The obtained results were compared with the results of observations made at the Ny-Ålesund station. Due to the situation of the area in the polar region and the large amount of clouds, especially in summer, the annual sum of incoming solar radiation was small, amounting to an average of 2,237.8 MJ.m-2 per year. The mean air temperature in the considered period was -2.0°C. Its extreme values ranged from 15.2°C to -23.8°C. In the annual course, the highest mean temperature occurred in July (6.5°C), and the lowest in March (-7.8°C). The mean relative humidity of air was high (83%). The prevailing wind directions were from south and north sectors and this coincided with the orientation of Forlandsundet. The mean wind speed was 3.6 m.s-1. In the summer season in 1975–2017, a statistically significant air temperature increase was observed, reaching 0.28°C/10 years. The high variability of local weather conditions was caused mainly by atmospheric circulation and the impact of sea ice was much smaller in comparison. Copyright © 2019. Kejna and Sobota." "57119983700;57195681934;7003638602;6603174102;55850233200;7006593624;57191159699;6701845055;6701762451;","Laboratory study of the heterogeneous ice nucleation on black-carbon-containing aerosol",2019,"10.5194/acp-19-12175-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073059629&doi=10.5194%2facp-19-12175-2019&partnerID=40&md5=b095760a1a36dfb09305084dd81787b6","Soot and black carbon (BC) particles are generated in the incomplete combustion of fossil fuels, biomass, and biofuels. These airborne particles affect air quality, human health, aerosol-cloud interactions, precipitation formation, and climate. At present, the climate effects of BC particles are not well understood. Their role in cloud formation is obscured by their chemical and physical variability and by the internal mixing states of these particles with other compounds. Ice nucleation in field studies is often difficult to interpret. Nonetheless, most field studies seem to suggest that BC particles are not efficient ice-nucleating particles (INPs). On the other hand, laboratory measurements show that in some cases, BC particles can be highly active INPs under certain conditions. By working with well-characterized BC particles, our aim is to systematically establish the factors that govern the ice nucleation activity of BC. The current study focuses on laboratory measurements of the effectiveness of BC-containing aerosol in the formation of ice crystals in temperature and ice supersaturation conditions relevant to cirrus clouds. We examine ice nucleation on BC particles under watersubsaturated cirrus cloud conditions, commonly understood as deposition-mode ice nucleation. We study a series of wellcharacterized commercial carbon black particles with varying morphologies and surface chemistries as well as ethylene flame-generated combustion soot. The carbon black particles used in this study are proxies for atmospherically relevant BC aerosols. These samples were characterized by electron microscopy, mass spectrometry, and optical scattering measurements. Ice nucleation activity was systematically examined in temperature and saturation conditions in the ranges of 217 ≤ T ≤ 235 K and 1:0 ≤ Sice ≤ 1:5 and 0:59 ≤ Swater ≤ 0:98, respectively, using a SPectrometer for Ice Nuclei (SPIN) instrument, which is a continuous-flow diffusion chamber coupled with instrumentation to measure light scattering and polarization. To study the effect of coatings on INPs, the BC-containing particles were coated with organic acids found in the atmosphere, namely stearic acid, cis-pinonic acid, and oxalic acid. The results show significant variations in ice nucleation activity as a function of size, morphology, and surface chemistry of the BC particles. The measured ice nucleation activity dependencies on temperature, supersaturation conditions, and the physicochemical properties of the BC particles are consistent with an ice nucleation mechanism of pore condensation followed by freezing. Coatings and surface oxidation modify the initial formation efficiency of pristine ice crystals on BC-containing aerosol. Depending on the BC mate rial and the coating, both inhibition and enhancement in INP activity were observed. Our measurements at low temperatures complement published data and highlight the capability of some BC particles to nucleate ice under low ice supersaturation conditions. These results are expected to help refine theories relating to soot INP activation in the atmosphere. © 2019 Author(s)." "55461837700;54897465300;55268661300;","A robust constraint on the temperature and height of the extratropical tropopause",2019,"10.1175/JCLI-D-18-0339.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059652051&doi=10.1175%2fJCLI-D-18-0339.1&partnerID=40&md5=6728c22e6fdf82f63ed54961cd70d9e0","In a recent study, the authors hypothesize that the Clausius-Clapeyron relation provides a strong constraint on the temperature of the extratropical tropopause and hence the depth of mixing by extratropical eddies. The hypothesis is a generalization of the fixed-anvil temperature hypothesis to the global atmospheric circulation. It posits that the depth of robust mixing by extratropical eddies is limited by radiative cooling by water vapor-and hence saturation vapor pressures-in areas of sinking motion. The hypothesis implies that 1) radiative cooling by water vapor constrains the vertical structure and amplitude of extratropical dynamics and 2) the extratropical tropopause should remain at roughly the same temperature and lift under global warming. Here the authors test the hypothesis in numerical simulations run on an aquaplanet general circulation model (GCM) and a coupled atmosphere-ocean GCM (AOGCM). The extratropical cloud-top height, wave driving, and lapse-rate tropopause all shift upward but remain at roughly the same temperature when the aquaplanetGCMis forced by uniform surface warming of14K and when theAOGCMis forced by RCP8.5 scenario emissions. ''Locking'' simulations run on the aquaplanetGCMfurther reveal that 1) holding the water vapor concentrations input into the radiation code fixed while increasing surface temperatures strongly constrains the rise in the extratropical tropopause,whereas 2) increasing the water vapor concentrations input into the radiation code while holding surface temperatures fixed leads to robust rises in the extratropical tropopause. Together, the results suggest that roughly invariant extratropical tropopause temperatures constitutes an additional ''robust response'' of the climate system to global warming. © 2018 American Meteorological Society." "24477084600;7404871794;","Sea ice albedo from MISR and MODIS: Production, validation, and trend analysis",2019,"10.3390/rs11010009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059942496&doi=10.3390%2frs11010009&partnerID=40&md5=0a43aadb3df66308326154a6fd9dda29","The Multi-angle Imaging SpectroRadiometer (MISR) sensor onboard the Terra satellite provides high accuracy albedo products. MISR deploys nine cameras each at different view angles, which allow a near-simultaneous angular sampling of the surface anisotropy. This is particularly important to measure the near-instantaneous albedo of dynamic surface features such as clouds or sea ice. However, MISR's cloud mask over snow or sea ice is not yet sufficiently robust because MISR's spectral bands are only located in the visible and the near infrared. To overcome this obstacle, we performed data fusion using a specially processed MISR sea ice albedo product (that was generated at Langley Research Center using Rayleigh correction) combining this with a cloud mask of a sea ice mask product, MOD29, which is derived from the MODerate Resolution Imaging Spectroradiometer (MODIS), which is also, like MISR, onboard the Terra satellite. The accuracy of the MOD29 cloud mask has been assessed as > 90% due to the fact that MODIS has a much larger number of spectral bands and covers a much wider range of the solar spectrum. Four daily sea ice products have been created, each with a different averaging time window (24 h, 7 days, 15 days, 31 days). For each time window, the number of samples, mean and standard deviation of MISR cloud-free sea ice albedo is calculated. These products are publicly available on a predefined polar stereographic grid at three spatial resolutions (1 km, 5 km, 25 km). The time span of the generated sea ice albedo covers the months between March and September of each year from 2000 to 2016 inclusive. In addition to data production, an evaluation of the accuracy of sea ice albedo was performed through a comparison with a dataset generated from a tower based albedometer from NOAA/ESRL/GMD/GRAD. This comparison confirms the high accuracy and stability of MISR's sea ice albedo since its launch in February 2000. We also performed an evaluation of the day-of-year trend of sea ice albedo between 2000 and 2016, which confirm the reduction of sea ice shortwave albedo with an order of 0.4-1%, depending on the day of year and the length of observed time window. © 2018 by the authors." "57203786634;56643049500;57189849444;7101688905;7403315325;54409357200;8655002700;56684108300;57192410499;57206250294;55204527000;57211489431;35279029900;44361104800;","Time series of landsat imagery shows vegetation recovery in two fragile karst watersheds in southwest China from 1988 to 2016",2019,"10.3390/rs11172044","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071984550&doi=10.3390%2frs11172044&partnerID=40&md5=e6b9519fd1b62eabc2f1728cd3fa8716","Since the implementation of China's afforestation and conservation projects during recent decades, an increasing number of studies have reported greening trends in the karst regions of southwest China using coarse-resolution satellite imagery, but small-scale changes in the heterogenous landscapes remain largely unknown. Focusing on two typical karst regions in the Nandong and Xiaojiang watersheds in Yunnan province, we processed 2,497 Landsat scenes from 1988 to 2016 using the Google Earth Engine cloud platform and analyzed vegetation trends and associated drivers. We found that both watersheds experienced significant increasing trends in annual fractional vegetation cover, at a rate of 0.0027 year-1 and 0.0020 year-1, respectively. Notably, the greening trends have been intensifying during the conservation period (2001-2016) even under unfavorable climate conditions. Human-induced ecological engineering was the primary factor for the increased greenness. Moreover, vegetation change responded differently to variations in topographic gradients and lithological types. Relatively more vegetation recovery was found in regions with moderate slopes and elevation, and pure limestone, limestone and dolomite interbedded layer as well as impure carbonate rocks than non-karst rocks. Partial correlation analysis of vegetation trends and temperature and precipitation trends suggested that climate change played a minor role in vegetation recovery. Our findings contribute to an improved understanding of the mechanisms behind vegetation changes in karst areas and may provide scientific supports for local afforestation and conservation policies. © 2019 by the authors." "56264698200;55615716800;55235064100;6602164207;35235984200;","Revisiting Recent Elevation-Dependent Warming on the Tibetan Plateau Using Satellite-Based Data Sets",2019,"10.1029/2019JD030666","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070629010&doi=10.1029%2f2019JD030666&partnerID=40&md5=2e172a8e299c719819f622e6bd1d125a","Satellite data, characterized by extensive regional coverage and relatively high spatial resolution, have a distinct advantage for examining elevation-dependent warming (EDW) across rugged topography in mountain regions where there are sparse in situ observations. Based on recent (2001–2015) comprehensive satellite-based data sets (2 m air temperature, land surface temperature, snow cover, and daytime and nighttime cloud), this study finds that annual mean 2 m air temperature warming rates show rapid decrease above 4,500 m despite increasing from 2,000 to 4,500 m. This indicates a reversal in EDW at the highest elevations on the Tibetan Plateau, which is somehow different from the EDW derived from short-term land surface temperature presented in earlier research. The decrease of warming rate above 4,500 m coincides with the elevation at which most of the current solid water resources reside. Thus, their decline may be less rapid than previously thought. Trends in nighttime cloud and snow cover are both correlated with patterns of EDW on the Tibetan Plateau, but the leading factor varies on an annual and seasonal basis. These results provide important evidence for understanding EDW and its controlling mechanisms in an extreme high-elevation context. ©2019. The Authors." "7201473447;7005930090;36739413000;","Algorithms for the classification and characterization of aerosols: Utility verification of near-UV satellite observations",2019,"10.1117/1.JRS.13.014527","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064115657&doi=10.1117%2f1.JRS.13.014527&partnerID=40&md5=f92f8626dc7c17dd605ba660483dee02","Aerosol types were characterized and classified using multispectral satellite data. The role of near-UV data in the detection of absorbing aerosols, such as biomass burning aerosols (BBA) or mineral dust particles (DUST), was examined on a global scale. An absorbing aerosol index (AAI) was proposed and defined as the ratio of the satellite-observed radiance (R) at a wavelength of 0.412 μm [R (0.412)] to that at 0.380 μm [R (0.380)] that can also detect nonabsorbing-type aerosols. Initially, the numerical AAI values were estimated for the BBAs and DUST from measurements collected by the Advanced Earth Observing Satellite-2/Global Imager (ADEOS-2/GLI). The Japanese short mission ADEOS-2 carried the GLI instrument with observation channels in the near-UV region. Not only the AAI index but also the short-wavelength infrared measurements were utilized to determine the dust detection index (DDI) defined as the ratio of R (2.210) to R (0.380) in order to discriminate BBAs from DUST. In addition, the AAI and DDI values were evaluated for the detection of clouds. The results allowed the classification criteria for DUST, BBA, other types of aerosols and clouds to be obtained. The Second-Generation Global Imager (SGLI) sensor is onboard the Japanese Global Change Observation Mission-Climate (GCOM-C) (SHIKISAI in Japanese) satellite launched on December 23, 2017. The SGLI has multiple channels (19) including near-UV and polarization sensors in the red and near-IR wavelengths. We also demonstrated the advantages of the SGLI for near-UV and polarization data for aerosol remote sensing. An understanding of aerosol types facilitated subsequent aerosol retrieval. Then, retrieval for classified aerosols was made based on the radiation simulations with multispectral radiance by GLI and polarization measurements by Polarization and Directionality of the Earth's Reflectances (POLDER)-2, respectively, mounted on the ADEOS-2 satellite. The proposed algorithms are expected to be available not only for the analysis of the SGLI data but also for other future missions. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI." "57201942906;55717074000;57201418252;57217772325;7410041005;57191226379;56384704800;57203386948;8840527400;","Modeling Dust in East Asia by CESM and Sources of Biases",2019,"10.1029/2019JD030799","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070728343&doi=10.1029%2f2019JD030799&partnerID=40&md5=a3dacf0ec3750b7391f7b9500de6b1f4","East Asian dust has a significant impact on regional and global climate. In this study, we evaluate the spatial distributions and temporal variations of dust extinction profiles and dust optical depth (DOD) over East Asia simulated from the Community Earth System Model (CESM) with satellite retrievals from Luo, Wang, Ferrare, et al. (2015, https://doi.org/10.1029/2002JD002775), Luo, Wang, Zhang, et al. (2015, https://doi.org/10.1002/2014GL062111) (L15), Yu et al. (2015, https://doi.org/10.1016/j.rse.2014.12.010) (Y15), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level 3 products. Both L15 and Y15 are based on CALIPSO products but use different algorithms to separate dust from nondust aerosols. We find high model biases of dust extinction in the upper troposphere over the Taklamakan desert, Gobi desert, and Tibetan Plateau, especially in the summer (June-July-August). CESM with dust emission scheme of Kok, Mahowald, et al. (2014, https://doi.org/10.5194/acp-14-13023-2014) and Kok, Albani, et al. (2014, https://doi.org/10.5194/acp-14-13043-2014) has the best agreement with dust extinction profiles and DOD from L15 in the Taklamakan desert and Tibetan Plateau. CESM with the default dust emission scheme of Zender, Bian, and Newman (2003, https://doi.org/10.1029/2002JD002775) underpredicts DOD in the Tibetan Plateau compared with observations from L15 due to the underestimation of local dust emission. Large uncertainties exist in observations from L15, Y15, and CALIPSO level 3 products and have significant impacts on the model evaluation of dust spatial distributions. We also assess dust surface concentrations and 10-m wind speed with meteorological records from weather stations in the Taklamakan and Gobi deserts during dust events. CESM underestimates dust surface concentrations at most weather stations due to the inability of CESM to capture strong surface wind events. © 2019. American Geophysical Union. All Rights Reserved." "57193678066;56003449400;16403070500;57209062836;55293383500;9334208600;55804218100;35621504700;","Towards understanding the global and regional climatic impacts of Modoki magnitude",2019,"10.1016/j.gloplacha.2018.10.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055041706&doi=10.1016%2fj.gloplacha.2018.10.004&partnerID=40&md5=6ded8b4465cc74784e3dedf940072222","Earlier studies suggest that the frequency and the strength of ENSO Modoki events increased considerably since last few decades (1970–2010) resulting in a need to revisit the climatic impacts of varying magnitude of ENSO Modoki. Hence, to better understand the impact of ENSO Modoki amplitude over the tropical and extra-tropical regions, especially in the Pacific, Asian and African regions, we conducted ENSO Modoki sensitivity experiments using ICTP-AGCM (SPEEDY). One of the main interests of this study is to see how ICTP-AGCM can reproduce teleconnections induced by ENSO Modoki events and how sensitive is the global and regional climate to ENSO Modoki strength. SPEEDY model qualitatively reproduces the impact of ENSO Modoki over the Pacific, Atlantic, North and South America and African regions very well. However, it underestimates ENSO Modoki induced teleconnection patterns and associated changes in South Asia, particularly in the Indian region. This study suggests a nonlinear climatic response to increased magnitude of ENSO Modoki. Our results reveal that like conventional ENSO, ENSO Modoki also induces considerable impact over North Pacific (Atlantic) region and initiates strong PNA (NAO) like response. ENSO Modoki-induced negative/positive NAO-like response and associated changes in Southern Europe and North Africa region get significantly strong following increased intensity of El Niño/La Niña Modoki in the boreal winter. We further find that ENSO Modoki magnitude significantly impacts tropical and high latitude circulation cells. The positive phase of ENSO (El Niño) overall strengthens Hadley Cell and a reverse is true for La Niña phase. ENSO Modoki-induced strengthening and weakening of Hadley Cell induce significant impact over South Asian and African ITCZ convective regions through modification of ITCZ/monsoon circulation system. © 2018 Elsevier B.V." "57212123034;57211253255;26657627700;56649979200;37762452400;57204928115;57193353463;","Linkage between the Arctic Oscillation and summer climate extreme events over the middle reaches of Yangtze River Valley",2019,"10.3354/cr01542","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073165922&doi=10.3354%2fcr01542&partnerID=40&md5=29808a451db68ed59a8bec127c15ba63","The Arctic Oscillation (AO) is commonly recognized as a dominant large-scale mode influencing climate over the Northern Hemisphere. Here, the influences of May AO on summer (JJA) extreme precipitation events and summer extreme warm days over the middle reaches of Yangtze River Valley for the period 1961−2014 are investigated. Following a positive May AO, there are usually fewer summer extreme precipitation events but more summer extreme warm days over the middle reaches of Yangtze River Valley. Composite analyses show that positive May AO induces the northward displacement of the East Asian jet stream and northeastward displacement of the western Pacific subtropical high (WPSH), and causes a stronger, more northwestern subtropical northwest Pacific cyclone/anticyclone anomaly, as well as an anticyclonic circulation anomaly on the north side of the South China Sea, resulting in a northward shift of the rainfall belt and an enhancement of the East Asia summer monsoon. Therefore, the cumulative distribution probability of daily precipitation values shift significantly to a lower precipitation value, indicating lower probabilities of summer extreme precipitation events following positive May AO. A weakening of WPSH induces an anomalous sinking motion over the middle reaches of the Yangtze River Valley. The 850 hPa wind field shows southerly wind anomalies over the Jiang-Huai River Basin, which cause a decrease in total cloud cover, resulting in an increase in solar radiation flux. A significant shift of the daily maximum temperature probability distribution towards to higher values indicates higher probabilities of summer extreme warm day occurrences following positive May AO. This study will provide useful insights to help improve the understanding of the dynamics and projections of future regional extreme precipitation changes over the middle reaches of Yangtze River Valley. © The authors 2019." "57193958103;55624399200;6505932008;","Relative sensitivities of simulated rainfall to fixed shape parameters and collection efficiencies",2019,"10.1002/qj.3550","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066889240&doi=10.1002%2fqj.3550&partnerID=40&md5=2597adc3962564ef86a2e172c7b6a57f","Rainfall prediction by weather forecasting models is strongly dependent on the microphysical parametrization being utilized within the model. As forecasting models have become more advanced, they are more commonly using double-moment bulk microphysical parametrizations. While these double-moment schemes are more sophisticated and require fewer a priori parameters than single-moment parametrizations, a number of parameter values must still be fixed for quantities that are not Prognosed or diagnosed. Two such parameters, the width of the rain drop size distribution and the choice of collection efficiencies between liquid hydrometeors, are examined here. Simulations of deep convective storms were performed in which the collection efficiency dataset and the a priori width of the rain drop size distribution (RSD) were individually and simultaneously modified. Analysis of the results show that the a priori width of the RSD was a larger control on the total accumulated precipitation (a change of up to 75% over the typical values tested in this article) than the choice of collection efficiency dataset used (a change of up to 10%). Changing the collection efficiency dataset produces most of the impacts on precipitation rates through changes in the warm rain process rates. On the other hand, the decrease in precipitation with narrowing RSDs occurs in association with the following processes: (a) decreased rain production due to increased evaporation, (b) decreased rain production due to decreased ice melting, and (c) slower raindrop fall speed which leads to longer residency times and changes in rain self-collection. These results add to the growing body of work showing that the representation of hydrometeor size distributions is critically important, and suggests that more work should be done to better represent the width of the RSD in models, including further development of triple-moment and bin schemes. © 2019 Royal Meteorological Society" "57195636034;7004201825;7103415093;","Dynamical Downscaling of the Arctic Climate with a Focus on Polar Cyclone Climatology",2019,"10.1080/07055900.2017.1369390","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029425583&doi=10.1080%2f07055900.2017.1369390&partnerID=40&md5=7000e55cb927b87155a3f5e5084d5b0a","We present a dynamical downscaling of the Arctic climatology using a high-resolution implementation of the Polar Weather Research and Forecasting, version 3.6 (WRF3.6) model, with a focus on Arctic cyclone activity. The study period is 1979–2004 and the driving fields are data from the Hadley Centre Global Environmental Model, version 2, with an Earth System component (HadGEM2-ES) simulations. We show that the results from the Polar WRF model provide significantly improved simulations of the frequency, intensity, and size of cyclones compared with the HadGEM2-ES simulations. Polar WRF reproduces the intensity of winter cyclones found in ERA-Interim, the global atmospheric reanalysis produced by the European Centre for Medium-range Weather Forecasts (ECMWF), and suggests that the average minimum central pressure of the cyclones is about 10 hPa lower than that derived from HadGEM2-ES simulations. Although both models underestimate the frequency of summer Arctic cyclones, Polar WRF simulations suggest there are 10.5% more cyclones per month than do HadGEM2-ES results. Overall, the Polar WRF model captures more intense and smaller cyclones than are obtained in HadGEM2-ES results, in better agreement with the ERA-Interim reanalysis data. Our results also show that the improved simulations of Arctic synoptic weather systems contribute to better simulations of atmospheric surface fields. The Polar WRF model is better able to simulate both the spatial patterns and magnitudes of the ERA-Interim reanalysis data than HadGEM2-ES is; in particular, the latter overestimates the absorbed solar radiation in the Arctic basin by as much as 30 W m−2 and underestimates longwave radiation by about 10 W m−2 in summer. Our results suggest that the improved simulations of longwave and solar radiation are partly associated with a better simulation of cloud liquid water content in the Polar WRF model, which is linked to improvements in the simulation of cyclone frequency and intensity and the resulting transient eddy transports of heat and water vapour. ©, © Crown Copyright." "35207500900;55836409900;7403506476;7403247998;23019327900;55926591200;37060931400;","The intraseasonal and interannual variability of arctic temperature and specific humidity inversions",2019,"10.3390/ATMOS10040214","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069854380&doi=10.3390%2fATMOS10040214&partnerID=40&md5=a84ac23b4e6c0b82c3861806e99aa0d2","Temperature and humidity inversions are common in the Arctic's lower troposphere, and are a crucial component of the Arctic's climate system. In this study, we quantify the intraseasonal oscillation of Arctic temperature and specific humidity inversions and investigate its interannual variability using data from the Surface Heat Balance of the Arctic (SHEBA) experiment from October 1997 to September 1998 and the European Centre for Medium-Range Forecasts (ECMWF) Reanalysis (ERA)-interim for the 1979-2017 period. In January 1998, there were two noticeable elevated inversions and one surface inversion. The transitions between elevated and surface-based inversions were associated with the intraseasonal variability of the temperature and humidity differences between 850 and 950 hPa. The self-organizing map (SOM) technique is utilized to obtain the main modes of surface and elevated temperature and humidity inversions on intraseasonal time scales. Low (high) pressure and more (less) cloud cover are related to elevated (surface) temperature and humidity inversions. The frequency of strong (weak) elevated inversions over the eastern hemisphere has decreased (increased) in the past three decades. The wintertime Arctic Oscillation (AO) and Arctic Dipole (AD) during their positive phases have a significant effect on the occurrence of surface and elevated inversions for two Nodes only. © 2019 by the authors." "22433533300;57217756674;25649367200;7801692677;","Weather model fine-tuning with software container-based simulation platform",2019,"10.28974/idojaras.2019.2.3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068905916&doi=10.28974%2fidojaras.2019.2.3&partnerID=40&md5=b9ecbee3389f05d76f52cbfa6c5fcd48","⎯Fine-tuning of a weather model requires immense computational resources, however, such capacities are usually available on non-homogeneous IT platforms. In addition, development and operational application are typically performed on different, heterogeneous systems (from laptops to dedicated HPC servers or cloud computing environments). To manage scalability and platform independent portability, a new layer – supporting state-of-the-art software container technology and batch processing – has been introduced. Encouraged by prior successful benchmark tests of the WRF model, the effect of model setup has been investigated over 10 different cases, tested on 30 different configurations. Including different parameterizations, the results of 300 different runs can be compared in a uniform database, yielding a sufficiently wide pool of samples in order to obtain the configuration of the modeling system optimal to the scope of our research, based on a relatively objective selection method. Continuously expanding database of near real-time preliminary outputs gives the opportunity for run-time steering of the experiments. This research currently benefits the development of an aviation meteorological support system, in the meanwhile, our contributions could be applied in an even wider aspect, either from the applicability of big data technology point of view, or with respect to the given best practice model setup. © 2019, Hungarian Meteorological Service. All rights reserved." "36106370400;57203815874;57212216605;7102680152;57212220256;55923546200;55440534900;57201305884;26424128800;23967608200;55293421800;57212217948;55903815100;24385643100;35794658100;56571063800;7402548443;56442378900;6602892883;57212218365;7801565183;7006415284;6603825422;57212219835;7003968166;7102084129;57189748029;7004469744;","Overview of the antarctic circumnavigation expedition: Study of preindustrial-like aerosols and their climate effects (ACE-SPACE)",2019,"10.1175/BAMS-D-18-0187.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074602846&doi=10.1175%2fBAMS-D-18-0187.1&partnerID=40&md5=f8f7086b3f2acd60b28507ccc18991ec","The first results from ACE-SPACE highlight that the Southern Ocean is a region with highly heterogeneous aerosol properties. The areas around the strong westerly wind belt are characterized by significant sea spray contributions to the total particle and CCN number concentrations in the MBL. Future work will link detailed wave and wind observations to sea spray production. In the Ross and Amundsen Sea polynyas (leg 2), biogenic emissions appear to play an important role for CCN abundance. There are a number of open questions associated with this observation. First, even though this particular region was probed during a phytoplankton bloom period, it was not the only region with microbial activity but showed the clearest link to high CCN concentrations. Hence, either DMS production from dimethylsulfoniopropionate in the water and/or DMS fluxes into the atmosphere were enhanced. Second, the major pathway of how MSA is added to the particle phase remains to be identified. There are two possibilities: It can condense from the gas into the particle phase, or it can be added during cloud processing. The latter process would be consistent with the reduced efficiency of wet removal because of droplet evaporation or snowflake sublimation in the cold and dry airmasses from Antarctica. Our results also indicate that the absence of MSA-related processes in the aerosol model could explain the underestimation of CCN concentration, particularly in high aerosol-MSA regions. Given that the number of CCN influence Nd, this is an important issue to solve, especially close to the coast of Antarctica where clouds could impact the surface snow mass balance by influencing both the surface energy budget and precipitation. Further studies are planned that more closely investigate the linkages between CCN number concentrations and model simulations that take DMS emissions fluxes and particle phase MSA into account. A comparison of satellite-retrieved Nd90 and ship-based measurements of CCN shows a clear underestimation of CCN from remote sensing, even for coupled cloud cases. This is a strong indication of the importance of surface sources as opposed to the free troposphere for particle origin. Further investigation is underway to understand the cause of the discrepancy between the remote sensing and in situ measurements. We did not find direct evidence for new particle formation as an important source of CCN. However, some nucleation events were observed and a nucleation mode was present in the clustered particle size distributions. A dedicated study will investigate the gases involved in these events and the fate of the nucleation mode in the atmosphere. Our ice nucleating particle findings suggest that concentrations are lower than in Northern Hemisphere marine airmasses and that concentrations decreased from summer toward fall with only small differences between open-ocean and coastal Antarctic samples. The ACE-SPACE INP concentrations are also consistent with findings of a recent study in the Southern Ocean (McCluskey et al. 2018a), but much lower than results from several decades ago (Bigg 1973). More detailed studies including information on potential island effects, long-range transport and fluorescent and microbial particles are underway. The ACE-SPACE project is motivated by the idea of constraining uncertainty in anthropogenic radiative forcing from aerosol-cloud interactions through measurement of preindustrial-like aerosol-cloud interactions. We have shown that the in situ data are suitable for constraining the aerosol model for preindustrial-like conditions. After a detailed model-measurement comparison, we will use the aerosol model to further constrain uncertainties of global radiative forcing from aerosol-cloud interactions. © 2019 American Meteorological Society." "57208530894;9246517900;57191712049;10341067100;6602178158;6701606453;","Snowfall distribution and its response to the Arctic Oscillation: An evaluation of HighResMIP models in the Arctic using CPR/CloudSat observations",2019,"10.5194/gmd-12-3759-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071753512&doi=10.5194%2fgmd-12-3759-2019&partnerID=40&md5=a3ffbaa92b59f71e2ce553e15c873006","A realistic representation of snowfall in general circulation models (GCMs) of global climate is important to accurately simulate snow cover, surface albedo, high-latitude precipitation and thus the surface radiation budget. Hence, in this study, we evaluate snowfall in a range of climate models run at two different resolutions by comparing to the latest estimates of snowfall from the CloudSat Cloud Profiling Radar over the northern latitudes. We also evaluate whether the finer-resolution versions of the GCMs simulate the accumulated snowfall better than their coarse-resolution counterparts. As the Arctic Oscillation (AO) is the prominent mode of natural variability in the polar latitudes, the snowfall variability associated with the different phases of the AO is examined in both models and in our observational reference. We report that the statistical distributions of snowfall differ considerably between the models and CloudSat observations. While CloudSat shows an exponential distribution of snowfall, the models show a Gaussian distribution that is heavily positively skewed. As a result, the 10th and 50th percentiles, representing the light and median snowfall, are overestimated by up to factors of 3 and 1.5, respectively, in the models investigated here. The overestimations are strongest during the winter months compared to autumn and spring. The extreme snowfall represented by the 90th percentiles, on the other hand, is positively skewed, underestimating the snowfall estimates by up to a factor of 2 in the models in winter compared to the CloudSat estimates. Though some regional improvements can be seen with increased spatial resolution within a particular model, it is not easy to identify a specific pattern that holds across all models. The characteristic snowfall variability associated with the positive phase of AO over Greenland Sea and central Eurasian Arctic is well captured by the models. © Author(s) 2019." "7007034953;","Examination of Extreme Rainfall Events in Two Regions of the United States since the 19th Century",2019,"10.3934/environsci.2019.2.109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071726413&doi=10.3934%2fenvironsci.2019.2.109&partnerID=40&md5=1113c1bce0c9b812a63496a59affe69d","A common hypothesis regarding human-induced climate change is that precipitation processes will accelerate leading to an increasing magnitude of rainfall amounts on a daily time scale as the atmosphere warms. This assertion is supported by two physically demonstrable facts, (1) warmer air accommodates more water vapor, and (2) precipitation processes become more efficient as the cloud environment warms. However, by definition, extreme events are rare, and thus statistics of their occurrence and possible long-term changes present difficult challenges, some herein addressed. In any case, the observational datasets on which hypothesis tests may be carried out should cover the longest periods possible because precipitation can naturally vary considerably on even century time scales. In this study we focus on this temporal issue by building long-term daily precipitation datasets for twenty stations, ten along or near the US Pacific Coast (PC) and ten along or near the coast in the US Southeast (SE). Observations for these stations begin between 1840 and 1890 and end in 2018, using the water year (Oct to Sep) to define the annual period. For some metrics, e.g. the annual total precipitation or the number of days per year measuring greater than 25 mm, there is no discernable change over the most recent 145 years (1874-2018). For other metrics, e.g. the magnitude of the wettest day per year or the temporal distribution of the 29 wettest 2-day events in the past 145 years (i.e. nominal 1-in-5-year occurrence), there appears to be an increase in SE and a decrease in PC. Whether these trends are significant for the relatively short climate record of 145 years will be discussed with the conclusion being the limited time frame of analysis does not lead to decisive claims that these changes are outside of the range of natural variability. © 2019 the Author(s), licensee AIMS Press." "57193136041;26533420100;14071297000;35568218100;","Predictive capability of a high-resolution hydrometeorological forecasting framework coupling WRF cycling 3DVAR and continuum",2019,"10.1175/JHM-D-18-0219.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070073294&doi=10.1175%2fJHM-D-18-0219.1&partnerID=40&md5=da0ec11a99e539b1cfb84c53a812aa65","The typical complex orography of the Mediterranean coastal areas support the formation of the so-called back-building mesoscale convective systems (MCS) producing torrential rainfall often resulting in flash floods. As these events are usually very small-scaled and localized, they are hardly predictable from a hydrometeorological standpoint, frequently causing a significant amount of fatalities and socioeconomic damage. Liguria, a northwestern Italian region, is characterized by small catchments with very short hydrological response time and is thus extremely prone to the impacts of back-building MCSs. Indeed, Liguria has been hit by three intense back-building MCSs between 2011 and 2014, causing a total death toll of 20 people and several hundred millions of euros of damages. Consequently, it is necessary to use hydrometeorological forecasting frameworks coupling the finescale numerical weather prediction (NWP) outputs with rainfall-runoff models to provide timely and accurate streamflow forecasts. Concerning the aforementioned back-buildingMCS episodes that recently occurred in Liguria, this work assesses the predictive capability of a hydrometeorological forecasting framework composed by a kilometer-scale cloud-resolving NWP model (WRF), including a 6-h cycling 3DVAR assimilation of radar reflectivity and conventional weather stations data, a rainfall downscaling model [Rainfall Filtered Autoregressive Model (RainFARM)], and a fully distributed hydrological model (Continuum). A rich portfolio of WRF 3DVAR direct and indirect reflectivity operators has been explored to drive the meteorological component of the proposed forecasting framework. The results confirm the importance of rapidly refreshing and data intensive 3DVAR for improving the quantitative precipitation forecast, and, subsequently, the flash flood prediction in cases of back-building MCS events. © 2019 American Meteorological Society." "56550021100;57208461039;14020840100;57205727530;7004909806;","Assimilating cloudy and rainy microwave observations from SAPHIR on board Megha Tropiques within the ARPEGE global model",2019,"10.1002/qj.3456","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061303366&doi=10.1002%2fqj.3456&partnerID=40&md5=137d27588a784d7ae9702d1ef4dff384","The Megha-Tropiques satellite was launched in 2011 with a microwave sounder called SAPHIR onboard. This instrument probes the atmosphere with six channels around the 183.31 GHz water vapour absorption band. Its observations are sensitive to water vapour as well as to hydrometeors. This instrument was proven to be useful for data assimilation by different numerical weather prediction centres, in particular for clear-sky assimilation. At Météo-France, SAPHIR observations have been routinely assimilated in clear sky since 2015 in the ARPEGE global model. The present article introduces a framework to complement this clear-sky assimilation route by a new cloudy and rainy assimilation route for satellite microwave brightness temperatures. This framework is based on several steps including a Bayesian inversion of the SAPHIR brightness temperatures into relative humidity retrievals, which are then assimilated within the ARPEGE global model. This study presents the methodology of assimilation, including the development of two error models, one for the Bayesian inversion, and one for the observation errors of relative humidity retrievals within the ARPEGE 4D-Var data assimilation system. The forecast scores obtained with this methodology over a three-month period indicate a positive impact of SAPHIR cloudy and rainy observations within the ARPEGE system, in particular on tropical temperature and wind forecasts for which the improvements range from 0.5 to 1.7% on standard deviations with respect to the ECMWF analysis and up to a +60 h lead time. © 2018 Royal Meteorological Society" "57205495589;7103274591;44161353800;","A Simple Model of Convectively Coupled Equatorial Rossby Waves",2019,"10.1029/2018MS001433","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060224620&doi=10.1029%2f2018MS001433&partnerID=40&md5=87bed996c4b054ac13163c51a5fb3434","Intraseasonal oscillations affect the weather not just in the tropics but all around the globe. The convectively coupled equatorial Rossby wave is observed as the westward-moving intraseasonal oscillation. The fundamental physics of its coupling is still unknown; thus, many questions remain unanswered. How is its phase speed altered by convection? What makes it unstable? Why is it an intraseasonal oscillation? Using the Fuchs and Raymond model with linearized governing equations on an equatorial beta plane, first baroclinic mode vertical structure, and moisture and wind-induced surface heat exchange (WISHE) convective parametrizations, this paper seeks a fundamental analytical theory that can explain the basic features of the convectively coupled equatorial Rossby wave. The WISHE-moisture theory leads to a large-scale, unstable westward propagating mode in the n = 1 case, which we call the westward propagating WISHE-moisture mode. We find that the westward propagating WISHE-moisture mode is indeed the free equatorial Rossby wave in the absence of moisture closure and WISHE. It is propagating westward due to the beta effect, and it slows down when it is convectively coupled. Its phase speed decreases mainly due to WISHE and cloud-radiation interactions. The x-y structure of the pressure and horizontal winds is similar to the free and observed Rossby wave, with convergent net flow. The strongest easterlies are to the west of the precipitation maximum increasing the moisture in that area. The mode is unstable due to the interplay of surface fluxes and moisture, which increases as a function of zonal wavelength. © 2018. The Authors." "57189839562;57205417747;55324391100;57191629313;57194337878;55090241300;","Integration of UAV, Sentinel-1, and Sentinel-2 data for mangrove plantation aboveground biomass monitoring in Senegal",2019,"10.3390/rs11010077","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059940525&doi=10.3390%2frs11010077&partnerID=40&md5=c3d546190076fb5d45d5151dc958b2c9","Due to the increasing importance of mangroves in climate change mitigation projects, more accurate and cost-effective aboveground biomass (AGB) monitoring methods are required. However, field measurements of AGB may be a challenge because of their remote location and the difficulty to walk in these areas. This study is based on the Livelihoods Fund Oceanium project that monitors 10,000 ha of mangrove plantations. In a first step, the possibility of replacing traditional field measurements of sample plots in a young mangrove plantation by a semiautomatic processing of UAV-based photogrammetric point clouds was assessed. In a second step, Sentinel-1 radar and Sentinel-2 optical imagery were used as auxiliary information to estimate AGB and its variance for the entire study area under a model-assisted framework. AGB was measured using UAV imagery in a total of 95 sample plots. UAV plot data was used in combination with non-parametric support vector regression (SVR) models for the estimation of the study area AGB using model-assisted estimators. Purely UAV-based AGB estimates and their associated standard error (SE) were compared with model-assisted estimates using (1) Sentinel-1, (2) Sentinel-2, and (3) a combination of Sentinel-1 and Sentinel-2 data as auxiliary information. The validation of the UAV-based individual tree height and crown diameter measurements showed a root mean square error (RMSE) of 0.21 m and 0.32 m, respectively. Relative efficiency of the three model-assisted scenarios ranged between 1.61 and 2.15. Although all SVR models improved the efficiency of the monitoring over UAV-based estimates, the best results were achieved when a combination of Sentinel-1 and Sentinel-2 data was used. Results indicated that the methodology used in this research can provide accurate and cost-effective estimates of AGB in young mangrove plantations. © 2019 by the authors." "25029972600;6603022543;15849901700;57205554930;57205559562;7006019301;7101821786;","A 4D feature-tracking algorithm: A multidimensional view of cyclone systems",2019,"10.1002/qj.3436","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060527940&doi=10.1002%2fqj.3436&partnerID=40&md5=0c152f33c6a9f03c915ca372032ceacf","An objective four-dimensional (4D) algorithm developed to track extratropical relative vorticity anomaly 3D structure over time is introduced and validated. The STACKER algorithm, structured with the TRACKER single-level tracking algorithm as source of the single-level raw tracks, objectively combines tracks from various levels to determine the 3D structure of the cyclone (or anticyclone) events throughout their life cycle. STACKER works progressively, beginning with two initial levels and then adding additional levels to the stack in a bottom-up and/or top-down approach. This allows an iterative stacking approach, adding one level at a time, resulting in an optimized 4D determination of relative vorticity anomaly events. A two-stage validation process is carried out with the ECMWF reanalysis ERA-Interim dataset for the 2015 austral winter. First the overall tracking capability during an austral winter, taking into account a set of climate indicators and their impacts on Southern Hemisphere circulation, was compared to previous climatologies, in order to verify the density and distribution of the cyclone events detected by STACKER. Results show the cyclone density distribution is in very good agreement with previous climatologies, after taking into account potential differences due to climate variability and different tracking methodologies. The second stage focuses on three different long-lived events over the Southern Hemisphere during the winter of 2015, spanning seven different pressure levels. Both GOES satellite imagery, infrared and water vapour channels, and ERA-Interim cloud cover products are used in order to validate the tracks obtained as well as the algorithm's capability and reliability. The observed 3D cyclone structures and their time evolution are consistent with current understanding of cyclone system development. Thus, the two-stage validation confirms that the algorithm is suitable to track multilevel events, and can follow and analyse their 3D life cycle and develop full 3D climatologies and climate variability studies. © 2018 Royal Meteorological Society" "57210142729;57210158256;57210162862;57204003984;","How weather factors affect electricity consumption in the different times ranges: A study in the Bangkok metropolitan region of Thailand",2019,"10.18178/ijesd.2019.10.8.1182","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069734370&doi=10.18178%2fijesd.2019.10.8.1182&partnerID=40&md5=ad8145d94f7bd12de34ec1c5409bfb2c","This paper analyses how weather factors affect electricity consumption in different time ranges in the Bangkok metropolitan region of Thailand. To answer this question, we use every 30-min data from 2015 to 2017 to discover the relationship between the electricity consumption and seven weather factors including temperature, dew point, relative humidity, wind (quantity), pressure, rainfall and, cloud using Pearson correlation. While the majority of people tend to think that temperature is the factor that contributed to load the most, our statistical result shows that temperature only affects electricity consumption in the very short term (within one day). In the weekly and monthly range, the electricity load is mainly associated with dew point. Hence, in different time ranges, different weather and climate factors contribute to electricity load. It suggests that future research and practice to choose carefully the factors in terms of electricity consumption prediction in different time ranges. Copyright © 2019 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0)." "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." "7801685676;","Black carbon radiative forcing in south Mexico City, 2015",2019,"10.20937/ATM.2019.32.03.01","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068239770&doi=10.20937%2fATM.2019.32.03.01&partnerID=40&md5=5c117339ec82a82f775d3eed02810a69","Black carbon (BC) is a strong radiative forcer. Because of its multiple effects on climate change, BC has been located as the second important impact factor of climate change only after carbon dioxide. Sources of BC include mainly diesel vehicles and biomass burning. Mexico's pledges before the Paris Agreement are, between others, the reduction of BC emissions to up to 51% by 2030 compared with those in 2000. In order to know the exact contribution of BC to the emission inventory of Mexico it is necessary to estimate several BC properties, such as its radiative forcing and its effects on the radiative heating of the atmosphere, among others. In this work, a technique based on the available remote-sensing and ground-based data along with the Optical Properties of Aerosols and Clouds (OPAC) and the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) algorithms were used to estimate black carbon radiative forcing in the south of Mexico City during 2015. Land-based measurements were taken from a recently created monitoring network, the Aerosol Robotic Network (AERONET), and satellite measurements were obtained from the Moderate Resolution Imaging Spectroradiometer) (MODIS). Black carbon monthly concentrations along 2015 were between 1.9 and 4.1 μg/m3. Results show that monthly average radiative forcing on the top of the atmosphere over south Mexico City during 2015 was +30.2 ± 6.2 W/m2. November, December and January presented the highest radiative forcing values (+34.9, +46.9, +34.0, respectively). In addition, estimates of atmospheric heating show an average annual value of 0.85 ± 0.22 W/m2. Values of Ångström > 1, as obtained in this work, indicate that aerosols are of the urban type and freshly emitted. Also, low single scattering albedo values in increasing wavelengths show that aerosols are mainly from urban-industrial aerosols. © 2019 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera." "36706881700;57215729754;23020556600;23666736500;57138743300;56609369600;","Dust properties and radiative impacts at a suburban site during 2004-2017 in the North China Plain",2019,"10.3390/rs11161842","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071540134&doi=10.3390%2frs11161842&partnerID=40&md5=ef655fe0c72358b0f677ed24b0d56286","Aerosols and their radiative effects are of primary interest in climate research because of their vital influence on climate change. Dust aerosols are an important aerosol type in the North China Plain (NCP), mainly as a result of long-range transport, showing substantial spatiotemporal variations. By using measurements from the Aerosol Robotic Network (AERONET) between September 2004 and May 2017, and the space-borne Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) aerosol products, we investigated the properties of dust aerosols and their radiative effects at Xianghe (XH)-a suburban site in the NCP. Dust events occurred most frequently during spring (a total of 105 days) relative to the other three seasons (a total of 41 days) during the periods concerned. The dust aerosol optical depth (AOD) at 675 nm was at a maximum in spring (0.60 ± 0.44), followed (in decreasing order) by those in autumn (0.58 ± 0.39), summer (0.54 ± 0.15), and winter (0.53 ± 0.23). Cooling effects of dust aerosol radiative forcing (RF) at the bottom and top of the atmosphere tended to be strongest in spring (-96.72 ± 45.69 and -41.87 ± 19.66 Wm-2) compared to that in summer (-57.08 ± 18.54 and -25.54 ± 4.45 Wm-2), autumn (-72.01 ± 27.27 and -32.54 ± 15.18 Wm-2), and winter (-79.57 ± 32.96 and -37.05 ± 17.06 Wm-2). The back-trajectory analysis indicated that dust air mass at 500 m that arrived at XH generally originated from the Gobi and other deserts of northern China and Mongolia (59.8%), and followed by northwest China and Kazakhstan (37.2%); few dust cases came from northeast China (3.0%). A single-peaked structure with the maximum occurring at ~2 km was illustrated by all dust events and those sorted by their sources in three directions. Three typical dust events were specifically discussed to better reveal how long-range transport impacted the dust properties and radiative effects over the NCP. The results presented here are expected to improve our understanding of the physical properties of dust aerosols over the NCP and their major transport path and significant impacts on the regional solar radiation budget. © 2019 by the authors." "57197830093;16403070500;57211212890;","Observed evidence of enhanced probability of mesoscale convective system initiations due to land surface heterogeneity in semiarid East Asia",2019,"10.2151/SOLA.2019-026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073015462&doi=10.2151%2fSOLA.2019-026&partnerID=40&md5=f50d4334279d794d22fe4f94dcdcde64","This study investigated the impact of land surface heterogeneity on Mesoscale Convective System (MCS) initiations in East Asia, using geostationary satellite data during June-August from 1996 through 2018. The detected MCSs over land exhibited clear diurnal variation with the lowest existence frequency at 10:00 and highest initiation frequency during 12:00-17:00 local time. To quantify land surface heterogeneity, the spatial standard deviation of equivalent Black-Body Temperature (TBB) within a cloud-free 0.35° × 0.35° box (σLSTBB: Land Surface TBB) was computed for 10:00 each day. A comparison of the σLSTBB and MCS databases revealed that the probability of MCS initiations increased with increasing σLSTBB in East Mongolia while the probability was not sensitive to σLSTBB in East China. This indicated that MCSs tend to form over heterogeneous land surface conditions in the semiarid region. We found that the impact of land surface heterogeneity on MCS initiations was highest over flat terrain in East Mongolia, where the convection trigger due to topographically-induced circulation was absent. These results suggest that the impact of land surface heterogeneity on MCS initiations during the warm season varies with climate zones and terrain complexities in East Asia, with strongest impact in semiarid and flat regions. © The Author(s) 2019." "55566968300;7003375391;8626748100;26647624500;28567954600;57041195900;","Comparison of measured and modelled mean radiant temperature in the tropical urban environment",2019,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073152467&partnerID=40&md5=700e1f2a02d72e9ce69b525baa25addf","RayMan is the most popular software package for thermal comfort research and urban planning. RayMan simulates the mean radiant temperature (Tmrt) and provides assessment of the human-biometeorology for urban areas. In this study Tmrt simulated by RayMan (version 1.2) has been validated with results from the six-directional radiation measurements in tropical urban settings in Malaysia. In addition, a validation of the physiologically equivalent temperature (PET) simulated by RayMan is conducted for the first time in the tropical context. Tmrt values from RayMan1.2 show some agreement with the measured values during middle of the validated days; however there was high fluctuation over that time due to rapid changes in radiation by cloud appearing. The results also show that RayMan1.2 considerably underestimated Tmrt during morning and evening. The simulated PET values followed the same pattern of the simulated Tmrt. However the simulated PET had a closer estimation to the experimentally obtained PET. The study also noted that RayMan1.2 accuracy seems to be site-related. Its simplification to the 3-D radiation environment led to variations in simulation accuracy depending on urban morphology. Therefore improvements of the RayMan software for simple and complex urban settings and tropical climates are required. © 2019 UNIVERSITI PUTRA MALAYSIA." "57210193249;55713076400;","The precipitation hotspots of afternoon thunderstorms over the taipei basin: idealized numerical simulations",2019,"10.2151/JMSJ.2019-031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069885226&doi=10.2151%2fJMSJ.2019-031&partnerID=40&md5=b09aa334ef07e94f5f67b0a4d582c67f","In this study, the mechanism for precipitation hotspots (PHs) of locally developed afternoon thunderstorms in the Taipei Basin is investigated using a three-dimensional Vector Vorticity equation cloud-resolving Model (VVM) with an idealized topography and surface properties. A 500 m horizontal grid resolution is used in all experiments. The results show that the local circulation is a key for PHs at the south of the Taipei Basin. The two valleys guide background southwesterly (SW) flow along with the sea breezes to penetrate into the basin. The urban heat island (UHI) effect enhances the sea breeze convergence at the south of the basin and produces strong convection there. The interactions between cold pools generated by the convection and the sea breezes produce northward propagating new convective cells. Besides, the background wind direction is important in determining the location of sea breeze convergence. If the background wind direction changes from westerly (W) to west-northwesterly (WNW), there might be no precipitation at all in the basin. This study suggests that the idealized experiments also provide a useful framework for studying the impacts of future climate changes on the PHs in the Taipei Basin by applying the pseudo-global warming approach. © The Author(s) 2019." "57203355816;55547111359;14526045600;","Aerosol characteristics over the northwestern indo-gangetic plain: Clear-sky radiative forcing of composite and black carbon aerosol",2019,"10.4209/aaqr.2017.09.0339","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063958151&doi=10.4209%2faaqr.2017.09.0339&partnerID=40&md5=903d1191c65467458b1812224946c719","The present study examines the aerosol characteristics over Patiala in northwestern India from October 2013 to June 2014. The average mass concentration of the total suspended particulates (TSP) varied from 117 to 301 µg m–3, with PM10 accounting for ~63–83% from October to February (P1) and decreasing to less than ~40% from March to June (P2). The aerosol optical depth (AOD500) exhibited its highest values during October (0.818) and its lowest during April (0.332), with the wavelength dependence differing significantly on a temporal scale. The Ångstrom exponent (α380-870) values indicated a relatively high quantity of fine-mode particles over the study region during P1 as compared to P2, which is consistent with the PM measurements. The average monthly mass concentration of the climate forcing agent black carbon (BC) varied from 2.4 to 12 µg m–3, with the highest mass concentration in December and the lowest in June. The average monthly single scattering albedo (SSA500) derived from the OPAC (Optical Properties of Aerosols and Clouds) model varied from 0.890 to 0.947, with lower values during P1 than P2. The average monthly clear-sky direct atmospheric aerosol radiative forcing (ATM ARF) estimated by the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model ranged between +12 and +36 Wm–2 over the study region. Even though the mass fraction of BC averaged over the study period was only 2.4% of the total mass of the composite aerosol, its contribution to net ATM ARF was found to be significant (> 60%), indicating that BC contributes significantly to warming on a regional scale. These results improve our understanding of the impact of BC and composite aerosol on the earth’s radiation budget and hence on regional climate. © Taiwan Association for Aerosol Research." "36630113600;6507872620;55914801800;56438937700;","Urban population exposure to tropospheric ozone: A multi-country forecasting of SOMO35 using artificial neural networks",2019,"10.1016/j.envpol.2018.10.051","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055965377&doi=10.1016%2fj.envpol.2018.10.051&partnerID=40&md5=fc22d6557e00c257103deb60bda2f2f8","Urban population exposure to tropospheric ozone is a serious health concern in Europe countries. Although there are insufficient evidence to derive a level below which ozone has no effect on mortality WHO (World Health Organization) uses SOMO35 (sum of means over 35 ppb) in their health impact assessments. Is this paper, the artificial neural network (ANN) approach was used to forecast SOMO35 at the national level for a set of 24 European countries, mostly EU members. Available ozone precursors’ emissions, population and climate data for the period 2003–2013 were used as inputs. Trend analysis had been performed using the linear regression of SOMO35 over time, and it has demonstrated that majority of the studied countries have a decreasing trend of SOMO35 values. The created models have made majority of predictions (≈60%) with satisfactory accuracy (relative error <20%) on testing, while the best performing model had R2 = 0.87 and overall relative error of 33.6%. The domain of applicability of the created models was analyzed using slope/mean ratio derivate from the trend analysis, which was successful in distinguishing countries with high from countries with low prediction errors. The overall relative error was reduced to <14%, after the pool of countries was reduced based on the abovementioned criterion. Urban population exposure to tropospheric ozone (SOMO35) at the national level can be accurately forecasted by an artificial neural network approach. © 2018 Elsevier Ltd" "57194056931;36021525100;36843654900;57194061527;7201959225;","Investigating the performance of coupled WRF-ROMS simulations of Hurricane Irene (2011) in a regional climate modeling framework",2019,"10.1016/j.atmosres.2018.08.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053001504&doi=10.1016%2fj.atmosres.2018.08.017&partnerID=40&md5=89fb468c0570902421a9d724972dfdf1","Hurricane Irene (2011) was a category 3 tropical storm that resulted in severe flooding, causing at least 40 deaths and more than $15 billion in damaged property along the US northeastern seaboard (Avila and Cangialosi, 2011). This work analyzes the sensitivity of numerical simulations of this devastating storm to the physical parameterizations in the Weather Research and Forecasting (WRF) model and a coupled modeling framework (WRF and the Regional Ocean Modeling System). Simulations were conducted in two 16-member physics ensembles, each included two radiation schemes, two cumulus schemes, two microphysics schemes, and two planetary boundary layer schemes. The simulations were evaluated primarily on the accuracy of the simulated track and the intensity of the storm compared to observations over a period of 5 days centered on the storm's maximum intensity. Cumulus and planetary boundary layer parameterizations were the most influential physics schemes with radiation and microphysics having much smaller effects. The simulated track, intensity, translational speed, and rainfall rate were particularly sensitive to cumulus schemes given the differences in representation of shallow convection. Tracks and rainfall rates also showed sensitivity to the inclusion or exclusion of local effects in the parameterization of planetary boundary layer processes. Using a grid spacing of 12 km, coupling an ocean model to WRF affected the storm track (with increased sensitivity to the cumulus scheme selected) and translational speed, but had very little effect on the rainfall rate or intensity of the storm. In terms of track accuracy, the optimal combination of physics parameterizations for WRF is not necessarily optimal for the coupled WRF-ROMS system. © 2018 Elsevier B.V." "57040213900;57190126041;57212508292;24172313200;57212509636;","Interdecadal Variability of Summer Precipitation Efficiency in East Asia",2019,"10.1155/2019/3563024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076894552&doi=10.1155%2f2019%2f3563024&partnerID=40&md5=3d6cf5c8f5ee159fafa2e282ac748b2b","Precipitation efficiency (PE) is a crucial physical quantity in convective processes, describing the efficiency of rainfall generation from cloud detrainment. Although the importance of PE in extreme precipitation events is widely accepted, the evolution of PE in the warming climate and the associated moisture processes in East Asia are still not well understood. To address these issues, the interdecadal variability of PE in East Asia during summer in 1979-2016 is investigated in this study. Two major modes of summertime precipitation efficiency are identified using Empirical Orthogonal Function (EOF) analysis. The leading EOF mode (EOF1) has a dipole pattern that reveals the variations of mean precipitation efficiency. The second EOF mode (EOF2) presents a quadrupole pattern that shows changes in the variability of precipitation efficiency. Both EOF modes exhibit significant interdecadal variability (IDV). The IDV of EOF1 is closely associated with the phase change of the Pacific decadal oscillation (PDO). The Pacific sea surface temperature anomalies associated with the PDO can excite wind anomalies that significantly modulate moisture transport and further alter the mean precipitation efficiency in East Asia. The IDV of EOF2 can be attributed to the interdecadal change of occurrence frequency of Eastern Pacific El Niño-Southern Oscillation (ENSO) events, which affect water vapor transport by inducing an East Asia-Pacific teleconnection-like wave train anomaly pattern. The IDV patterns of precipitation efficiency for both the mean value and variability will improve the ability to predict precipitation in East Asia. © 2019 Jian Wang et al." "57194097309;8096902500;7003420834;56153733100;6506700584;","The Impact of Concave Coastline on Rainfall Offshore Distribution over Indonesian Maritime Continent",2019,"10.1155/2019/6839012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060156296&doi=10.1155%2f2019%2f6839012&partnerID=40&md5=12cfd6514bc3e701b08f5c24ac3c1870","Indonesian Maritime Continent has the second longest coastline in the world, but the characteristics of offshore rainfall and its relation to coastline type are not clearly understood. As a region with eighty percent being an ocean, knowledge of offshore rainfall is important to support activity over oceans. This study investigates the climatology of offshore rainfall based on TRMM 3B42 composite during 1998-2015 and its dynamical atmosphere which induces high rainfall intensity using WRF-ARW. The result shows that concave coastline drives the increasing rainfall over ocean with Cenderawasih Bay (widest concave coastline) having the highest rainfall offshore intensity (16.5 mm per day) over Indonesian Maritime Continent. Monthly peak offshore rainfall over concave coastline is related to direction of concave coastline and peak of diurnal cycle influenced by the shifting of low level convergence. Concave coastline facing the north has peak during northwesterly monsoonal flow (March), while concave coastline facing the east has peak during easterly monsoonal flow (July). Low level convergence zone shifts from inland during daytime to ocean during nighttime. Due to shape of concave coastline, land breeze strengthens low level convergence and supports merging rainfall over ocean during nighttime. Rainfall propagating from the area around inland to ocean is approximately 5.4 m/s over Cenderawasih Bay and 4.1 m/s over Tolo Bay. Merger rainfall and low level convergence are playing role in increasing offshore rainfall over concave coastline. © 2019 Furqon Alfahmi et al." "55937815500;15834571900;55460969900;57192701783;","Earth observations-based evapotranspiration in Northeastern Thailand",2019,"10.3390/rs11020138","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060724766&doi=10.3390%2frs11020138&partnerID=40&md5=ac971a92d95abc2bc07a0ccd0e4e2486","Thailand is characterized by typical tropical monsoon climate, and is suffering serious water related problems, including seasonal drought and flooding. These issues are highly related to the hydrological processes, e.g., precipitation and evapotranspiration (ET), which are helpful to understand and cope with these problems. It is critical to study the spatiotemporal pattern of ET in Thailand to support the local water resource management. In the current study, daily ET was estimated over Thailand by ETMonitor, a process-based model, with mainly satellite earth observation datasets as input. One major advantage of the ETMonitor algorithm is that it introduces the impact of soil moisture on ET by assimilating the surface soil moisture from microwave remote sensing, and it reduces the dependence on land surface temperature, as the thermal remote sensing is highly sensitive to cloud, which limits the ability to achieve spatial and temporal continuity of daily ET. The ETMonitor algorithm was further improved in current study to take advantage of thermal remote sensing. In the improved scheme, the evaporation fraction was first obtained by land surface temperature-vegetation index triangle method, which was used to estimate ET in the clear days. The soil moisture stress index (SMSI) was defined to express the constrain of soil moisture on ET, and clear sky SMSI was retrieved according to the estimated clear sky ET. Clear sky SMSI was then interpolated to cloudy days to obtain the SMSI for all sky conditions. Finally, time-series ET at daily resolution was achieved using the interpolated spatio-temporal continuous SMSI. Good agreements were found between the estimated daily ET and flux tower observations with root mean square error ranging between 1.08 and 1.58 mm d -1 , which showed better accuracy than the ET product from MODerate resolution Imaging Spectroradiometer (MODIS), especially for the forest sites. Chi and Mun river basins, located in Northeast Thailand, were selected to analyze the spatial pattern of ET. The results indicate that the ET had large fluctuation in seasonal variation, which is predominantly impacted by the monsoon climate. © 2019 by the authors." "7201398636;7005868133;7005872245;","Microphysical process comparison of three microphysics parameterization schemes in the WRF model for an idealized squall-line case study",2019,"10.1175/MWR-D-18-0249.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075811560&doi=10.1175%2fMWR-D-18-0249.1&partnerID=40&md5=a4609cd854f1ed4606569ddd2504ca4d","Three bulk microphysics schemes with different complexities in the Weather Research and ForecastingModel are compared in terms of the individual microphysical process terms of the hydrometeor mass andnumber mixing ratio tendency equations in an idealized 2D squall-line case. Through evaluation of theseprocess terms and of hydrometeor size distributions, it is shown that the differences in the simulated population characteristics of snow, graupel, and rainwater are the prominent factors contributing to the differences in the development of the simulated squall lines using these schemes. In this particular case, the gustfront propagation speed produced by the Thompson scheme is faster than in the other two schemes during thefirst 2 h of the simulation because it has a larger dominant graupel size. After 2 h into the simulation, theinitially less intense squall lines in the runs using the WSM6 and Morrison schemes start to catch up inintensity and development to the run using the Thompson scheme. Because the dominant size of graupelparticles in the runs using the WSM6 and Morrison schemes is smaller, these particles take more time to fallbelow the freezing level and enhance the rainwater production and its evaporative cooling. In the run usingthe Thompson scheme, the graupel production slows down at later times while the snow particle growthincreases, leading to more snow falling below the freezing level to melt and surpass graupel particle melting inthe production of rainwater. © 2019 American Meteorological Society." "57210289844;37068471000;7005528388;36095558300;","The Spectral Dimension of Arctic Outgoing Longwave Radiation and Greenhouse Efficiency Trends From 2003 to 2016",2019,"10.1029/2019JD030428","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070197462&doi=10.1029%2f2019JD030428&partnerID=40&md5=29ced359ca3d01810cff7269d236bfb4","Fourteen years of spectral fluxes derived from collocated Atmospheric Infrared Sounder (AIRS) and Clouds and the Earth's Radiant Energy System (CERES) observations are used in conjunction with AIRS retrievals to examine the trends of zonal mean spectral outgoing longwave radiation (OLR) and greenhouse efficiency (GHE) in the Arctic. AIRS retrieved profiles are fed into a radiative transfer model to generate synthetic clear-sky spectral OLR. Trends are derived from the simulated clear-sky spectral OLR and GHE and then compared with their counterparts derived from collocated observations. Spectral trends in different seasons are distinctively different. March and September exhibit positive trends in spectral OLR over the far-IR dirty window and mid-IR window region for most of the Arctic. In contrast, spectral OLR trends in July are negative over the far-IR dirty window and can be positive or negative in the mid-IR window depending on the latitude. Sensitivity studies reveal that surface temperature contributes much more than atmospheric temperature and humidity to the spectral OLR and GHE trends, while the contributions from the latter two are also discernible over many spectral regions (e.g., trends in the far-IR dirty window in March). The largest increase of spectral GHE is seen north of 80°N in March across the water vapor v2 band and far-IR. When the secular fractional change of spectral OLR is less than that of surface spectral emission, an increase of spectral GHE can be expected. Spectral trend analyses reveal more information than broadband trend analyses alone. ©2019. American Geophysical Union. All Rights Reserved." "56568319200;7202408584;7006218108;6701620591;7005456532;","A new clear-sky method for assessing photosynthetically active radiation at the surface level",2019,"10.3390/ATMOS10040219","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069855260&doi=10.3390%2fATMOS10040219&partnerID=40&md5=a639302d15461c948796b6ba6feeda55","A clear-sky method to estimate the photosynthetically active radiation (PAR) at the surface level in cloudless atmospheres is presented and validated. It uses a fast and accurate approximation adopted in several radiative transfer models, known as the k-distribution method and the correlated-k approximation, which gives a set of fluxes accumulated over 32 established wavelength intervals. A resampling technique, followed by a summation, are applied over the wavelength range [0.4, 0.7] μm in order to retrieve the PAR fluxes. The method uses as inputs the total column contents of ozone and water vapor, and optical properties of aerosols provided by the Copernicus Atmosphere Monitoring Service. To validate the method, its outcomes were compared to instantaneous global photosynthetic photon flux density (PPFD) measurements acquired at seven experimental sites of the Surface Radiation Budget Network (SURFRAD) located in various climates in the USA. The bias lies in the interval [-12, 61] μmol m-2 s-1 ([-1, 5] % in values relative to the means of the measurements at each station). The root mean square error ranges between 37 μmol m-2 s-1 (3%) and 82 μmol m-2 s-1 (6%). The squared correlation coefficient fluctuates from 0.97 to 0.99. This comparison demonstrates the high level of accuracy of the presented method, which offers an accurate estimate of PAR fluxes in cloudless atmospheres at high spatial and temporal resolutions useful for several bio geophysical models. © 2019 by the authors." "57210687618;36961988200;","Dry and semidry tropical cyclones",2019,"10.1175/JAS-D-18-0357.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075573988&doi=10.1175%2fJAS-D-18-0357.1&partnerID=40&md5=53e4e699956b3d6f425133fa68f8cea8","It is widely believed that tropical cyclones are an intrinsically moist phenomenon, requiring evaporation and latent heat release in cumulus convection. Recent numerical modeling by Mrowiec et al., however, challenged this conventional wisdom by finding the formation of axisymmetric dry tropical cyclones in dry radiative–convective equilibrium (RCE). This paper addresses ensuing questions about the stability of dry tropical cyclones in 3D, the moist–dry vortex transition, and whether existing theories for intensity, size, and structure apply to dry cyclones. A convection-permitting model is used to simulate rotating 3D RCE, with surface wetness (0–1) and surface temperature (240–300 K) smoothly varying between dry and moist states. Tropical cyclones spontaneously form and persist for tens of days in both moist and dry/cold states, as well as part of the relatively moist/warm intermediate parameter space. As the surface is dried or cooled, cyclones weaken, both in absolute terms and relative to their potential intensities. Dry and semidry cyclones have smaller outer radii but similar-sized or larger convective centers compared to moist cyclones, consistent with existing structural theory. Strikingly, spontaneous cyclogenesis fails to occur at moderately low surface wetness values and intermediate surface temperatures of 250–270 K. Simulations with time-varying surface moisture and sea surface temperatures indicate this range of parameter space is a barrier to spontaneous genesis but not cyclone existence. Dry and semidry tropical cyclones in rotating RCE provide a compelling model system to further our understanding of real moist tropical cyclones. © 2019 American Meteorological Society." "56194231200;56789684500;57206129502;57210719777;7005264401;","An implicit algebraic turbulence closure scheme for atmospheric boundary layer simulation",2019,"10.1175/JAS-D-18-0375.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074094011&doi=10.1175%2fJAS-D-18-0375.1&partnerID=40&md5=65832443ad7b4f37ad3ad6d74d8ea4c1","Turbulence parameterization plays a critical role in the simulation of many weather regimes. For challenging cases such as the stratocumulus-capped boundary layer (SCBL), traditional schemes can produce unrealistic results even when a fine large-eddy-simulation (LES) resolution is used. Here we present an implicit generalized linear algebraic subfilter-scale model (iGLASS) to better represent unresolved turbulence in the simulation of the atmospheric boundary layer, at both standard LES and so-called terra incognita (TI) resolutions. The latter refers to a range of model resolutions where turbulent eddies are only partially resolved, and therefore the simulated processes are sensitive to the representation of unresolved turbulence. iGLASS is based on the truncated conservation equations of subfilter-scale (SFS) fluxes, but it integrates the full equations of the SFS turbulence kinetic energy and potential energy to retain ‘‘memory’’ of the SFS turbulence. Our evaluations suggest iGLASS can perform significantly better than traditional eddy-diffusivity models and exhibit skills comparable to the dynamic reconstruction model (DRM). For a neutral boundary layer case run at LES resolution, the simulation using iGLASS exhibits a wind profile that reasonably matches the similarity-theory solution. For an SCBL case with 5-m vertical resolution, iGLASS maintains more realistic cloud water profiles and boundary layer structure than traditional schemes. The SCBL case is also tested at TI resolution, and iGLASS also exhibits superior performance. iGLASS permits significant backscatter, whereas traditional models allow forward scatter (diffusion) only. As a physics-based approach, iGLASS appears to be a viable alternative for turbulence parameterization. © 2019 American Meteorological Society." "8636686400;23981460100;57209717156;57209715749;","Scientific data management in the age of big data: An approach supporting a resilience index development effort",2019,"10.3389/fenvs.2019.00072","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068506260&doi=10.3389%2ffenvs.2019.00072&partnerID=40&md5=ab7e05a7141c2bbae49c2495ebfa04a9","The increased availability of publicly available data is, in many ways, changing our approach to conducting research. Not only are cloud-based information resources providing supplementary data to bolster traditional scientific activities (e.g., field studies, laboratory experiments), they also serve as the foundation for secondary data research projects such as indicator development. Indicators and indices are a convenient way to synthesize disparate information to address complex scientific questions that are difficult to measure directly (e.g., resilience, sustainability, well-being). In the current literature, there is no shortage of indicator or index examples derived from secondary data with a growing number that are scientifically focused. However, little information is provided describing the management approaches and best practices used to govern the data underpinnings supporting these efforts. From acquisition to storage and maintenance, secondary data research products rely on the availability of relevant, high-quality data, repeatable data handling methods and a multi-faceted data flow process to promote and sustain research transparency and integrity. The U.S. Environmental Protection Agency recently published a report describing the development of a climate resilience screening index which used over one million data points to calculate the final index. The pool of data was derived exclusively from secondary sources such as the U.S. Census Bureau, Bureau of Labor Statistics, Postal Service, Housing and Urban Development, Forestry Services and others. Available data were presented in various forms including portable document format (PDF), delimited ASCII and proprietary format (e.g., Microsoft Excel, ESRI ArcGIS). The strategy employed for managing these data in an indicator research and development effort represented a blend of business practices, information science, and the scientific method. This paper describes the approach, highlighting key points unique for managing the data assets of a small-scale research project in an era of ""big data"". © 2019 Harwell, Vivian, McLaughlin and Hafner." "6603562731;6603944055;35467405200;17135286400;","Uv reflectance of the ocean from dscovr/epic: Comparisons with a theoretical model and aura/omi observations",2019,"10.1175/JTECH-D-18-0150.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076271250&doi=10.1175%2fJTECH-D-18-0150.1&partnerID=40&md5=fcf4d95b03f2eea158c79dd579eba244","Ultraviolet (UV) data collected over the ocean by the Earth Polychromatic Imaging Camera (EPIC) on the Deep Space Climate Observatory (DSCOVR) are used. The Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm adapted for EPIC processing performs cloud detection, aerosol retrievals, and atmospheric correction providing the water-leaving reflectance of the ocean at 340 and 388 nm. The water-leaving reflectance is an indicator of the presence of absorbing and scattering constituents in seawater. The retrieved water-leaving reflectance is compared with full radiative transfer calculations based on a model of inherent optical properties (IOP) of ocean water in UV. The model is verified with data collected on the Aerosol Characterization Experiments (ACE) Asia cruise supported by the NASA Sensor Intercomparison for Marine Biological and Interdisciplinary Ocean Studies (SIMBIOS) project. The model assumes that the ocean water IOPs are parameterized through a chlorophyll concentration. The radiative transfer simulations were carried out using the climatological chlorophyll concentration from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Aqua satellite. The EPIC-derived water-leaving reflectance is also compared with climatological Lambertian-equivalent reflectivity (LER) of the ocean derived from measurements of the Ozone Monitoring Instrument (OMI) on board the NASA polar-orbiting Aura satellite. The EPIC reflectance agrees well (within 0.01) with the model reflectance except for oligotrophic oceanic areas. For those areas, the model reflectance is biased low by about 0.01 at 340 nm and up to 0.03 at 388 nm. The OMI-derived climatological LER is significantly higher than the EPIC water-leaving reflectance, largely due to the surface glint contribution. The globally averaged difference is about 0.04. © 2019 American Meteorological Society." "57203386948;57206456336;56990731400;7004174939;57203102974;8045690700;55742914900;56722821200;24081888700;56239378700;7003865921;7404061081;6701416358;55669656100;23134745300;7003597653;","Estimates of African Dust Deposition Along the Trans-Atlantic Transit Using the Decadelong Record of Aerosol Measurements from CALIOP, MODIS, MISR, and IASI",2019,"10.1029/2019JD030574","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070727377&doi=10.1029%2f2019JD030574&partnerID=40&md5=5ef5545b52a68f9f5c5bfc36e9b67a71","Deposition of mineral dust into ocean fertilizes ecosystems and influences biogeochemical cycles and climate. In situ observations of dust deposition are scarce, and model simulations depend on the highly parameterized representations of dust processes with few constraints. By taking advantage of satellites' routine sampling on global and decadal scales, we estimate African dust deposition flux and loss frequency (a ratio of deposition flux to mass loading) along the trans-Atlantic transit using the three-dimensional distributions of aerosol retrieved by spaceborne lidar (Cloud-Aerosol Lidar with Orthogonal Polarization [CALIOP]) and radiometers (Moderate Resolution Imaging Spectroradiometer [MODIS], Multiangle Imaging Spectroradiometer [MISR], and Infrared Atmospheric Sounding Interferometer [IASI]). On the basis of a 10-year (2007-2016) and basin-scale average, the amount of dust deposition into the tropical Atlantic Ocean is estimated at 136-222 Tg/year. The 65-83% of satellite-based estimates agree with the in situ climatology within a factor of 2. The magnitudes of dust deposition are highest in boreal summer and lowest in fall, whereas the interannual variability as measured by the normalized standard deviation with mean is largest in spring (28-41%) and smallest (7-15%) in summer. The dust deposition displays high spatial heterogeneity, revealing that the meridional shifts of major dust deposition belts are modulated by the seasonal migration of the intertropical convergence zone. On the basis of the annual and basin mean, the dust loss frequency derived from the satellite observations ranges from 0.078 to 0.100 day-1, which is lower than model simulations by up to factors of 2 to 5. The most efficient loss of dust occurs in winter, consistent with the higher possibility of low-altitude transported dust in southern trajectories being intercepted by rainfall associated with the intertropical convergence zone. The satellite-based estimates of dust deposition can be used to fill the geographical gaps and extend time span of in situ measurements, study the dust-ocean interactions, and evaluate model simulations of dust processes. ©2019. American Geophysical Union. All Rights Reserved." "36550625700;55508264900;34882256000;","Spatial and spectral pattern identification for the automatic selection of high-quality MODIS images",2019,"10.1117/1.JRS.13.014510","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062687963&doi=10.1117%2f1.JRS.13.014510&partnerID=40&md5=03549990c5bc49e44d4a16c8232c04c1","Remote sensing is providing an increasing number of crucial data about Earth. Systematic revisitation time allows the analysis of long time series as well as imagery utilization in the most interesting moments. Nevertheless, the current huge amount of data makes essential the usage of automatic methods to select the best captures, as many of them are not useful because of clouds, shadows, etc. Because of that, one of the characteristics of the more recent missions is the distribution, along with the spectral data, of a large amount of quality ancillary datasets. These datasets can act synergistically in the aim of selecting the best quality images, but the criteria they provide are not always enough. Indeed, these datasets are often used on a per pixel basis and the spatial pattern of the different spectral bands is forgotten, so ignoring the key information they can provide for our goals. With this aim, our work takes one of the most successful instruments in remote sensing, MODIS, and demonstrates, through geostatistical techniques, that the role of the spatial patterns of the spectral bands can effectively improve image selection in a complex (for climate, relief, and vegetation and crop phenology) region of 63,700 km2. The results show that band 01 (red) is the preferred one, as it achieves a 13% higher success than when only using quality bands criteria: A 94% global accuracy (66 true classifications, and only four omissions and one commission error). A second, important finding, is that the geostatistical selection improves results when using any band, except for band 02 (NIR1), which makes our proposal potentially useful for most remote sensing missions. Finally, the method can be executed in a reasonable computing time due to previously developed high-performance computing techniques. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI." "56985207700;6507615174;26657811000;","A new strategy for the estimation of plume height from clast dispersal in various atmospheric and eruptive conditions",2019,"10.1016/j.epsl.2018.10.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055081998&doi=10.1016%2fj.epsl.2018.10.007&partnerID=40&md5=e1ae9b344b1b8f89f94bd674ad6f9837","Plume height is an important parameter routinely used to characterize and classify explosive eruptions. Though the strategies to estimate key eruption source parameters such as erupted volume and mass flow rate have evolved over the past few decades, the determination of plume height of past eruptions is still mostly based on empirical approaches that do not account for the new developments in plume modelling based on the interaction of plume and wind. Here we present a revised strategy for the retrieval of plume height from field data that accounts for key aspects of plume dynamics and particle sedimentation, which include: i) the effect of wind advection on the buoyant plume, ii) a new parameterization of the gravitational spreading of the umbrella cloud for distances smaller than the radius of the plume, iii) the effect of particle shape on particle sedimentation, iv) the effect of different atmospheric profiles in different climate zones, v) three-dimensional wind, temperature and pressure data, and vi) topography. In particular, as wind can affect the dynamics and height of the plume, new computed sedimentation patterns are more complex and result in non-linear relationships between downwind and crosswind deposition. Our method is tested against observations of the 2011 eruption of Shinmoedake (Japan), the 1980 eruption of Mount St Helens (USA), and the 1991 eruption of Pinatubo (Philippines). These are well-constrained examples of small, intermediate, and high intensity eruptions, respectively. Intensity scenarios are introduced to account for the non-unique relation between plume height and particle sedimentation resulting from wind advection of volcanic plumes. We further demonstrate that needle-like and disk-like particle shapes can have downwind distances 36 to 70% larger than the equivalent spheres. In addition, we find that the effect of latitude on the determination of plume height is more significant for low and intermediate intensity scenarios with a discrepancy between 7 and 20%. © 2018 The Author(s)" "57210943125;49963767500;55916982900;","Remote sensing of ice phenology and dynamics of Europe's largest coastal lagoon (the Curonian Lagoon)",2019,"10.3390/rs11172059","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071981497&doi=10.3390%2frs11172059&partnerID=40&md5=6550a7c2b1fc07615af61ea3d200ae9b","A first-ever spatially detailed record of ice cover conditions in the Curonian Lagoon (CL), Europe's largest coastal lagoon located in the southeastern Baltic Sea, is presented. The multi-mission synthetic aperture radar (SAR) measurements acquired in 2002-2017 by Envisat ASAR, RADARSAT-2, Sentinel-1 A/B, and supplemented by the cloud-free moderate imaging spectroradiometer (MODIS) data, are used to document the ice cover properties in the CL. As shown, satellite observations reveal a better performance over in situ records in defining the key stages of ice formation and decay in the CL. Using advantages of both data sources, an updated ice season duration (ISD) record is obtained to adequately describe the ice cover season in the CL. High-resolution ISD maps provide important spatial details of ice growth and decay in the CL. As found, ice cover resides longest in the south-eastern CL and along the eastern coast, including the Nemunas Delta, while the shortest ice season is observed in the northern CL. During the melting season, the ice melt pattern is clearly shaped by the direction of prevailing winds, and ice drift velocities obtained from a limited number of observations range within 0.03-0.14 m/s. The pronounced shortening of the ice season duration in the CL is observed at a rate of 1.6-2.3 days year-1 during 2002-2017, which is much higher than reported for the nearby Baltic Sea regions. While the timing of the freeze onset and full freezing has not changed much, the dates of the final melt onset and last observation of ice have a clear decreasing pattern toward an earlier ice break-up and complete melt-off due to an increase of air temperature strongly linked to the North Atlantic Oscillation (NAO). Notably, the correlation between the ISD, air temperature, and winter NAO index is substantially higher when considering the lagoon-averaged ISD values derived from satellite observations compared to those derived from coastal records. The latter clearly demonstrated the richness of the satellite observations that should definitely be exploited in regional ice monitoring programs. © 2019 by the authors." "57201215819;55154955700;55547114594;56135632400;7403974034;36726337300;36771492300;","Assessment of atmospheric aerosols from two reanalysis products over Australia",2019,"10.1016/j.atmosres.2018.08.026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053464300&doi=10.1016%2fj.atmosres.2018.08.026&partnerID=40&md5=624beb6830bef0f87c350a76eceb1562","Assessments of atmospheric aerosols from reanalysis are important for understanding uncertainty in model simulations, and ultimately predictions, such as for solar power or air quality forecasts and assessments. This study intercompares total aerosol optical depth (AOD) and dust AOD (DAOD) from two global reanalyses datasets, the European Centre for Medium-Range Weather Forecasts (ECMWF) Monitoring Atmospheric Composition and Climate (MACC) and the NASA Modern-Era Retrospective Analysis for Research-2 (MERRA-2). These are evaluated against AeroSpan (Aerosol characterisation via Sun photometry: Australian Network) ground observations which forms part of the Aerosol Robotic Network (AERONET) over the Australian continent for the 2002–2012 period. During dust storms, AeroSpan/AERONET AOD measurements were missing due to cloud screening. To overcome validation limitations in sun photometry for dust events, a nephelometer's scattering coefficient is qualitatively compared against reanalysis of DAOD at a key dust storm activation site, Tinga Tingana in South Australia (~200 km east of Lake Eyre). A specific extreme event that occurred in 2009 originating from the Lake Eyre basin, a major dust source covering one-sixth of Australia, was studied. The results show that MERRA-2 reanalysis overestimates monthly total AOD twice as much compared to AeroSpan/AERONET ground observations but seems better correlated against AeroSpan/AERONET than ECMWF/MACC. Mean data of MERRA-2 time series over 10 years provide lower DAOD values and lower dust aerosol estimates than ECMWF/MACC reanalysis (over the Lake Eyre basin with spatial averaging). Specifically at Tinga Tingana, the correlation from MERRA-2 (0.45 correlation) and ECMWF/MACC (0.43 correlation) against AeroSpan/AERONET's AOD were similar. Between MERRA-2 and ECMWF/MACC decade long daily gridded DAOD, the correlation coefficient was high at 0.73, again indicating similarity between the datasets. MERRA-2 total AOD correlation is significantly higher (by 0.26) against AeroSpan/AERONET than ECMWF/MACC. MERRA-2 also provides higher AOD values in extreme cases which may correspond to dust storms. During dust storms, a hybrid strategy using nephelometers and hourly reanalysis from MERRA-2 is able to identify dust storms better than AeroSpan/AERONET. Overall, this work can enable and inform better aerosol data assimilation into forecast models such as for solar energy, agriculture or air quality over Australia. © 2018 Elsevier B.V." "57195469687;54400787600;6507482782;57210948650;6602228395;","Studying the impact on urban health over the greater delta region in Egypt due to aerosol variability using optical characteristics from satellite observations and ground-based AERONET measurements",2019,"10.3390/rs11171998","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071984228&doi=10.3390%2frs11171998&partnerID=40&md5=4d25f8fa9439bd25a17a23dac884192c","This research addresses the aerosol characteristics and variability over Cairo and the Greater Delta region over the last 20 years using an integrative multi-sensor approach of remotely sensed and PM10 ground data. The accuracy of these satellite aerosol products is also evaluated and compared through cross-validation against ground observations from the AErosol RObotic NETwork (AERONET) project measured at local stations. The results show the validity of using Multi-angle Imaging Spectroradiometer (MISR) and Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on the Terra and Aqua platforms for quantitative aerosol optical depth (AOD) assessment as compared to Ozone Monitoring Instrument (OMI), Sea-viewingWide Field-of-view Sensor (SeaWiFS), and POLarization and Directionality of the Earth's Reflectances (POLDER). In addition, extracted MISR-based aerosol products have been proven to be quite effective in investigating the characteristics of mixed aerosols. Daily AERONET AOD observations were collected and classified using K-means unsupervised machine learning algorithms, showing five typical patterns of aerosols in the region under investigation. Four seasonal aerosol emerging episodes are identified and analyzed using multiple indicators, including aerosol optical depth (AOD), size distribution, single scattering albedo (SSA), and Ångström exponent (AE). The movements and detailed aerosol composition of the aforementioned episodes are demonstrated using NASA's Goddard Space Flight Center (GSFC) back trajectories model in collaboration with aerosol subtype products from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission. These episodes indicate that during the spring, fall, and summer, most of the severe aerosol events are caused by dust or mixed related scenarios, whereas during winter, aerosols of finer size lead to severe heavy conditions. It also demonstrates the impacts of different aerosol sources on urban human health, which are presented by the variations of multiple parameters, including solar radiation, air temperature, humidity, and UV exposure. Scarce ground PM10 data were collected and compared against satellite products, yet owed to their discrete nature of availability, our approach made use of the Random Decision Forest (RDF) model to convert satellite-based AOD and other meteorological parameters to predict PM10. The RDF model with inputs from the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) and Global Land Data Assimilation System (GLDAS) datasets improves the performance of using AOD products to estimate PM10 values. The connection between climate variability and aerosol intensity, as well as their impact on health-related PM2.5 over Egypt is also demonstrated. © 2019 by the authors." "7004932211;26026749200;57200702127;","Increased Frequency of Extreme Tropical Deep Convection: AIRS Observations and Climate Model Predictions",2018,"10.1029/2018GL079423","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059038194&doi=10.1029%2f2018GL079423&partnerID=40&md5=50fa153ca8d47005d23e73c17d013a8d","Atmospheric Infrared Sounder (AIRS) data from the tropical oceans (30°N to 30°S) are used to derive the probability of the process resulting in deep convective clouds (DCCs) as function of the sea surface temperature (SST). For DCC at or below the tropopause the onset temperature of this process shifts at the same rate as the increase in the mean SST. For tropopause overshooting DCC, which are associated with extreme rain events, the shift of the onset temperature is slower, causing their frequency to increase by about 21%/K of warming of the oceans. This sensitivity is not inconsistent with the sensitivity of the increase of extreme deep convective rain in the National Center for Atmospheric Research Community Atmosphere Model version 5 model for a warmer SST. The mean of the 36 fifth Phase of the Coupled Model Intercomparison Project models predicts a 2.7 K warmer tropical SST by the end of this century, resulting in a 60% increases in the frequency of tropopause overshooting DCC. ©2018. American Geophysical Union. All Rights Reserved." "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." "55715899800;57203082302;35274839300;36236882900;35270245200;7102358267;7005923344;7005077299;56748084500;7003279098;55739684700;","The Flux and Emission of Dimethylsulfide From the Great Barrier Reef Region and Potential Influence on the Climate of NE Australia",2018,"10.1029/2018JD029210","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058978633&doi=10.1029%2f2018JD029210&partnerID=40&md5=e1cf3209475d493b2f3451343b37b972","Concentrations of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS), and DMS flux are reported for the Great Barrier Reef (GBR), Great Barrier Reef Lagoon (GBRL), and Coral Sea. Generally higher concentrations of dimethylsulfoniopropionate and DMS occurred in coral reef waters, compared with GBRL concentrations. DMS flux from GBR coral reefs in summer ranged from nondetectable to 153 μmol m −2 d −1 (mean 6.4), while winter fluxes ranged from 0.02 to 15 μmol m −2 d −1 (mean 2.4). No significant seasonal difference in DMS flux occurred for the GBRL. High DMS w concentrations and DMS fluxes periodically occur at coral reefs during very low tides and elevated sea surface temperatures (SSTs). For the GBRL and GBR coral reefs there was a significant correlation between seawater DMS w concentrations and SST (p < 0.001), up to temperatures of 30 °C. During coral bleaching DMS flux from reefs almost completely shuts down when SSTs are >30 °C. The GBRL and associated coral reefs emit 439 and 32 MmolS per year, respectively. Cyclones on average produce 170 MmolS to the GBR atmosphere in summer. This amount can markedly increase during severe cyclones such as severe tropical Cyclone Debbie in March 2017. Overall, the annual DMS emission estimate from the GBRL and coral reefs in the GBR is 0.64 GmolS, with cyclones contributing 27% or greater of the annual emission estimate, depending on the cyclone intensity. Oxidation of atmospheric DMS can potentially affect solar radiation, SSTs, low-level cloud cover, and rainfall causing cooling and warming of the climate in the GBR region as recent modeling predicts. ©2018. American Geophysical Union. All Rights Reserved." "57194527119;6602809597;55224074800;7102953444;","From Point to Area: Worldwide Assessment of the Representativeness of Monthly Surface Solar Radiation Records",2018,"10.1029/2018JD029169","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058939699&doi=10.1029%2f2018JD029169&partnerID=40&md5=161f83a1a562b14f585c5f2040403590","The representativeness of surface solar radiation (SSR) point observations is an important issue when using them in combination with gridded data. We conduct a comprehensive near-global (50°S to 55°N) analysis on the representativeness of SSR point observations on the monthly mean time scale. Thereto, we apply the existing concepts of decorrelation lengths (δ), spatial sampling biases (β), and spatial sampling errors (ε) to three high-resolution gridded monthly mean SSR data sets (CLARA, SARAH-P, and SARAH-E) provided by the Satellite Application Facility on Climate Monitoring. While δ quantifies the area for which a point observation is representative, β and ε are uncertainty estimates with respect to the 1-degree reference grid (G). For this grid we find a near-global average δ G =3.4°, β G =1.4 W/m 2 , and ε G =7.6 W/m 2 with substantial regional differences. Disregarding tropical, mountainous, and some coastal regions, monthly SSR point observations can largely be considered representative of a 1-degree grid. Since ε is an uncorrectable error the total uncertainty when combining point with 1-degree gridded data is roughly 40% higher than the uncertainty of station-based SSR measurements alone if a rigorous bias correction is applied. Cloud cover and terrain data can at maximum explain 50% of the patterns of the representativeness metrics. We apply our methodology to the stations of the Baseline Surface Radiation Network. Overall, this study shows that representativeness is strongly dependent on local conditions and that all three metrics (δ, β, and ε) must be considered for a comprehensive assessment of representativeness. ©2018. The Authors." "55710921100;23003259600;57215729754;16481561000;55689034100;56141759400;55687255900;57194201381;57194201701;41462164500;57132509000;57191334192;57131646800;56068376200;","Multiyear Ground-Based Measurements of Aerosol Optical Properties and Direct Radiative Effect Over Different Surface Types in Northeastern China",2018,"10.1029/2018JD029141","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059094007&doi=10.1029%2f2018JD029141&partnerID=40&md5=0f2098c890959acd14af5caad7f433f6","Aerosol microphysical and optical properties as well as aerosol direct radiative effect (ADRE) were measured at a few ground sites to investigate aerosol optical-radiative characteristics in northeastern China. Bimodal size distributions showed a dominance of fine mode particles at Shenyang, a megacity, and more impacts from larger particles at Fushun and Dalian, industrial and coastal sites, respectively. High aerosol optical depths at 440 nm in July (0.67–1.25) were ascribed to hygroscopic effects or cloud processing. Single scattering albedos at 440 nm show strong to moderate absorption at the urban and industrial sites (0.84–0.86) and weaker absorption at the coastal and rural sites (0.92–0.94). The single scattering albedo wavelength dependence implied influences of dust at the urban, industrial, and coastal regions (shorter wavelengths) and biomass emissions at the rural site (longer wavelengths). Absorptive aerosol optical depths at the urban and industrial sites were ~2.5 and 3.7 times higher than at the coastal and rural sites. Large negative ADREs at the bottom of the atmosphere at the urban and industrial sites implied strong surface cooling and the larger ADREs at the top of the atmosphere at the coastal site indicated more cooling of the Earth-atmosphere system. The main aerosol types at the urban and industrial sites were mixed absorbing particles, while weakly-absorbing fine mode particles dominated the coastal and rural sites. This study provides new information on the aerosol distributions and potential regional climate effects of aerosols in northeastern China. ©2018. American Geophysical Union. All Rights Reserved." "56662710300;57203898312;56712001000;24734304300;7003482642;57211811048;","Atmospheric rivers over the Arctic: Lagrangian characterisation of their moisture sources",2018,"10.3390/w11010041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059341259&doi=10.3390%2fw11010041&partnerID=40&md5=782c7f999541bde6648e2dadec72042c","In recent years, the Arctic has become a subject of special interest due to the drastic effect of climate change over the region. Despite that there are several mechanisms that influence the Arctic region; some recent studies have suggested significant influences of moisture transport over the observed loss of sea ice. Moisture transport can affect the region in different ways: direct precipitation over the region, radiative effect from the cloud cover and through the release of latent heat. Atmospheric rivers (ARs) represent one of the main events involved in moisture transport from the tropics to the mid-latitudes and despite having been shown especially relevant on the northward advection, their effect over the Arctic has not been deeply investigated. The aim of this work was to establish the groundwork for future studies about the effect of ARs linked to moisture transport over the Arctic region. For this purpose, an automated algorithm was used to identify regions of maximum AR occurrence over the Arctic. This was done by analysing the number of AR detections every month over a band of 10° of latitude centred on 60° N. The Lagrangian model FLEXPART was used to find the areas where the ARs take their moisture to the Arctic. Using this model, the anomalous moisture contribution to these baroclinic structures was analysed taking into account only the dates of AR occurrence. From the results, it appears that the main moisture sources for AR events extend over the North Atlantic and North Pacific oceans; moreover, the local input of moisture over the region of maximum AR occurrence seems to be especially relevant. In general terms, moisture comes from major evaporative areas over the western part of the oceanic regions in the band between 30° and 40° N for most months in the year, showing a continental origin in the summer months. This behaviour agrees with the climatological moisture transport into the Arctic determined in previous studies. However, in special association with AR events, an intensification of local moisture uptake is observed over the area of maximum AR activity and nearby. The study of the origin of this moisture and associated anomalies for Arctic ARs is an important step in the analysis of the effect of these structures on the Arctic environment. © 2018 by the authors." "55548464400;7004585020;14028349500;55967393300;","Rain attenuation prediction model for satellite communications based on the Météo-France ensemble prediction system PEARP",2018,"10.5194/nhess-18-3327-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058970884&doi=10.5194%2fnhess-18-3327-2018&partnerID=40&md5=91d1375edb2ecb264262adbe964c2e45","This paper presents an example of the usage of ensemble weather forecasting for the control of satellite-based communication systems. Satellite communication systems become increasingly sensitive to weather conditions as their operating frequency increases to avoid electromagnetic spectrum congestion and enhance their capacity. In the microwave domain, electromagnetic waves that are conveying information are attenuated between the satellite and Earth terminals in the presence of hydrometeors (mostly rain drops and more marginally cloud droplets). To maintain a reasonable level of service availability, even with adverse weather conditions considering the scarcity of amplification power in spacecraft, fade mitigation techniques have been developed. The general idea behind those fade mitigation techniques is to reroute, change the characteristics or reschedule the transmission in the case of too-significant propagation impairments. For some systems, a scheduling on how to use those mechanisms some hours in advance is required, making assumptions on the future weather conditions affecting the link. To this aim the use of weather forecast data to control the attenuation compensation mechanisms seems of particular interest to maximize the performances of the communication links and hence of the associated economic value. A model to forecast the attenuation on the link based on forecasted rainfall amounts from deterministic or ensemble weather forecasting is presented and validated. In a second phase, the model's application to a simplified telecommunication system allows us to demonstrate the valuable contribution of weather forecasting in the system's availability optimization or in the system's throughput optimization. The benefit of using ensemble forecasts rather than deterministic ones is demonstrated as well. © 2018 Author(s)." "6603731262;57204076890;23009023800;8666819700;7004056699;56997048300;7003624664;6602671297;7004177188;57200190326;6507532116;7005902195;8871497700;7005755464;22934624000;8535468100;7007162501;7004858482;26643041500;35461255500;","Direct effect of aerosols on solar radiation and gross primary production in boreal and hemiboreal forests",2018,"10.5194/acp-18-17863-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058861311&doi=10.5194%2facp-18-17863-2018&partnerID=40&md5=59387f345d51806154d81e047963ae67","The effect of aerosol loading on solar radiation and the subsequent effect on photosynthesis is a relevant question for estimating climate feedback mechanisms. This effect is quantified in the present study using ground-based measurements from five remote sites in boreal and hemiboreal (coniferous and mixed) forests of Eurasia. The diffuse fraction of global radiation associated with the direct effect of aerosols, i.e. excluding the effect of clouds, increases with an increase in the aerosol loading. The increase in the diffuse fraction of global radiation from approximately 0.11 on days characterized by low aerosol loading to 0.2-0.27 on days with relatively high aerosol loading leads to an increase in gross primary production (GPP) between 6 % and 14 % at all sites. The largest increase in GPP (relative to days with low aerosol loading) is observed for two types of ecosystems: a coniferous forest at high latitudes and a mixed forest at the middle latitudes. For the former ecosystem the change in GPP due to the relatively large increase in the diffuse radiation is compensated for by the moderate increase in the light use efficiency. For the latter ecosystem, the increase in the diffuse radiation is smaller for the same aerosol loading, but the smaller change in GPP due to this relationship between radiation and aerosol loading is compensated for by the higher increase in the light use efficiency. The dependence of GPP on the diffuse fraction of solar radiation has a weakly pronounced maximum related to clouds. © 2018. This work is distributed under the Creative Commons Attribution 4.0 License." "57194590031;56216874200;","Machine learning-based retrieval of benthic reflectance and Posidonia oceanica seagrass extent using a semi-analytical inversion of Sentinel-2 satellite data",2018,"10.1080/01431161.2018.1519289","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054865532&doi=10.1080%2f01431161.2018.1519289&partnerID=40&md5=b71cfaeb6ca51c7419348c086305aedc","In the epoch of the human-induced climate change, seagrasses can mitigate the resulting negative impacts due to their carbon sequestration ability. The endemic and dominant in the Mediterranean Posidonia oceanica seagrass contains the largest stocks of organic carbon among all seagrass species, yet it undergoes a significant regression in its extent. Therefore, suitable quantitative assessment of its extent and optically shallow environment are required to allow good conservation and management practices. Here, we parameterise a semi-analytical inversion model which employs above-surface remote sensing reflectance of Sentinel-2A to derive water column and bottom properties in the Thermaikos Gulf, NW Aegean Sea, Greece (eastern Mediterranean). In the model, the diffuse attenuation coefficients are expressed as functions of absorption and backscattering coefficients. We apply a comprehensive pre-processing workflow which includes atmospheric correction using C2RCC (Case 2 Regional CoastColour) neural network, resampling of the lower spatial resolution Sentinel-2A bands to 10m/pixel, as well as empirical derivation of water bathymetry and machine learning-based classification of the resulting bottom properties using the Support Vector Machines. SVM-based classification of benthic reflectance reveals ~300 ha of P. oceanica seagrass between 2 and 16 m of depth, and yields very high producer and user accuracies of 95.3% and 99.5%, respectively. Sources of errors and uncertainties are discussed. All in all, recent advances in Earth Observation in terms of optical satellite technology, cloud computing and machine learning algorithms have created the perfect storm which could aid high spatio-temporal, large-scale seagrass habitat mapping and monitoring, allowing for its integration to the Analysis Ready Data era and ultimately enabling more efficient management and conservation in the epoch of climate change. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group." "24822250800;36785148100;7005034568;","Radiometric correction of observations from microwave humidity sounders",2018,"10.5194/amt-11-6617-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058823269&doi=10.5194%2famt-11-6617-2018&partnerID=40&md5=f893c4a2515ee87a611ac0c95fe42455","The Advanced Microwave Sounding Unit-B (AMSU-B) and Microwave Humidity Sounder (MHS) are total power microwave radiometers operating at frequencies near the water vapor absorption line at 183 GHz. The measurements of these instruments are crucial for deriving a variety of climate and hydrological products such as water vapor, precipitation, and ice cloud parameters. However, these measurements are subject to several errors that can be classified into radiometric and geometric errors. The aim of this study is to quantify and correct the radiometric errors in these observations through intercalibration. Since the bias in the calibration of microwave instruments changes with scene temperature, a two-point intercalibration correction scheme was developed based on averages of measurements over the tropical oceans and nighttime polar regions. The intercalibration coefficients were calculated on a monthly basis using measurements averaged over each specified region and each orbit, then interpolated to estimate the daily coefficients. Since AMSU-B and MHS channels operate at different frequencies and polarizations, the measurements from the two instruments were not intercalibrated. Because of the negligible diurnal cycle of both temperature and humidity fields over the tropical oceans, the satellites with the most stable time series of brightness temperatures over the tropical oceans (NOAA-17 for AMSU-B and NOAA-18 for MHS) were selected as the reference satellites and other similar instruments were intercalibrated with respect to the reference instrument. The results show that channels 1, 3, 4, and 5 of AMSU-B on board NOAA-16 and channels 1 and 4 of AMSU-B on board NOAA-15 show a large drift over the period of operation. The MHS measurements from instruments on board NOAA-18, NOAA-19, and MetOp-A are generally consistent with each other. Because of the lack of reference measurements, radiometric correction of microwave instruments remain a challenge, as the intercalibration of these instruments largely depends on the stability of the reference instrument. © 2018 Copernicus. All rights reserved." "55866510700;57205156548;57189444679;10739072200;56897131200;57140816300;11339750700;8871497700;26643041500;35461255500;","Refined classification and characterization of atmospheric new-particle formation events using air ions",2018,"10.5194/acp-18-17883-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058851759&doi=10.5194%2facp-18-17883-2018&partnerID=40&md5=4d43f524540d9b794882d348b4dc5084","Atmospheric new-particle formation (NPF) is a worldwide-observed phenomenon that affects the human health and the global climate. With a growing network of global atmospheric measurement stations, efforts towards investigating NPF have increased. In this study, we present an automated method to classify days into four categories including NPF events, non-events and two classes in between, which then ensures reproducibility and minimizes the hours spent on manual classification. We applied our automated method to 10 years of data collected at the SMEAR II measurement station in Hyytiälä, southern Finland using a Neutral cluster and Air Ion Spectrometer (NAIS). In contrast to the traditionally applied classification methods, which categorize days into events and non-events and ambiguous days as undefined days, our method is able to classify the undefined days as it accesses the initial steps of NPF at sub-3 nm sizes. Our results show that, on ĝ1/424 % of the days in Hyytiälä, a regional NPF event occurred and was characterized by nice weather and favourable conditions such as a clear sky and low condensation sink. Another class found in Hyytiälä is the transported event class, which seems to be NPF carried horizontally or vertically to our measurement location and it occurred on 17 % of the total studied days. Additionally, we found that an ion burst, wherein the ions apparently fail to grow to larger sizes, occurred on 18 % of the days in Hyytiälä. The transported events and ion bursts were characterized by less favourable ambient conditions than regional NPF events and thus experienced interrupted particle formation or growth. Non-events occurred on 41 % of the days and were characterized by complete cloud cover and high relative humidity. Moreover, for regional NPF events occurring at the measurement site, the method identifies the start time, peak time and end time, which helps us focus on variables within an exact time window to better understand NPF at a process level. Our automated method can be modified to work in other measurement locations where NPF is observed. © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License." "56001571800;22133985200;7201423091;55469200300;7402838215;7004944088;","High Depolarization Ratios of Naturally Occurring Cirrus Clouds Near Air Traffic Regions Over Europe",2018,"10.1029/2018GL079345","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058623943&doi=10.1029%2f2018GL079345&partnerID=40&md5=a98a999482201c9770c56408316cc476","Cirrus clouds have a large influence on the Earth's climate and anthropogenic activities such as aviation can alter their properties. Besides the formation of contrails, indirect effects on naturally occurring cirrus like increased heterogeneous freezing due to exhaust soot particles are discussed in the literature. However, hardly any observational study exists. In this work we present cirrus optical properties measured by an airborne lidar over Europe during the Midlatitude Cirrus experiment (ML-CIRRUS). One half of the cloud cases showed elevated depolarization ratios with a mode difference of 10 percentage points indicating differences in the clouds microphysical properties. Their origin can be traced back to highly frequented air traffic regions, and they show lower in-cloud ice supersaturations. Our analysis reveals no influence of embedded contrails and temperature. These results could be explained by an indirect aerosol effect where heterogeneous freezing is caused by aviation exhaust particles. ©2018. The Authors." "57195672133;56228672600;7103180783;","Influence of Central Siberian Snow-Albedo Feedback on the Spring East Asian Dust Cycle and Connection With the Preceding Winter Arctic Oscillation",2018,"10.1029/2018JD029385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058469481&doi=10.1029%2f2018JD029385&partnerID=40&md5=6dc7f873f92578828ffe4d75df9d4135","The Asian dust cycle has significant effects on the climate and environment, while its spatiotemporal variability and change mechanisms are not yet completely understood. Reanalysis data from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA2), data set are used to explore the spatiotemporal distribution of the East Asian dust cycle and possible reasons for the interannual variations. Based on the empirical orthogonal function analysis, the dominant mode of dust emissions from the East Asian deserts in the dust season (spring) shows that the Gobi Desert contributes most of the interannual variance of dust emissions in East Asia. The patterns of the regional circulation, temperature, and radiation are analyzed by regressing these variables against the principal component time series of the first empirical orthogonal function mode. The results show that the enhanced dust emissions are associated with a cyclonic circulation anomaly and cooling in the lower and middle troposphere over Central Siberia. The cooling is attributed to local snow-albedo and cloud-albedo feedbacks. The surface cooling is conducive to maintain the snow cover, whereas the cooling in the middle troposphere is associated with the increase of the relative humidity and cloud cover. The increased snow and cloud cover reflect more shortwave radiation, tending to maintain or amplify the surface cooling. It is also found that the negative phase of the Arctic Oscillation in winter initiates the surface cooling in the next spring and results in positive snow-albedo and cloud feedbacks in Central Siberia, eventually enhancing the East Asian dust cycle. ©2018. 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." "56757625500;25823275400;7102976560;57109884900;7004347243;55893823700;6603113016;9941600400;57076559300;8293692200;","Simulated Global Climate Response to Tropospheric Ozone-Induced Changes in Plant Transpiration",2018,"10.1029/2018GL079938","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058627159&doi=10.1029%2f2018GL079938&partnerID=40&md5=1037a31b0e31aa60588e7ef6b8d70de5","Tropospheric ozone (O 3 ) pollution is known to damage vegetation, reducing photosynthesis and stomatal conductance, resulting in modified plant transpiration to the atmosphere. We use an Earth system model to show that global transpiration response to near-present-day surface tropospheric ozone results in large-scale global perturbations to net outgoing long-wave and incoming shortwave radiation. Our results suggest that the radiative effect is dominated by a reduction in shortwave cloud forcing in polluted regions, in response to ozone-induced reduction in land-atmosphere moisture flux and atmospheric humidity. We simulate a statistically significant response of annual surface air temperature of up to ~ +1.5 K due to this ozone effect in vegetated regions subjected to ozone pollution. This mechanism is expected to further increase the net warming resulting from historic and future increases in tropospheric ozone. ©2018. American Geophysical Union. All Rights Reserved." "57193678066;16403070500;","Analysis of Climate Trends and Leading Modes of Climate Variability for MENA Region",2018,"10.1029/2018JD029003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057965706&doi=10.1029%2f2018JD029003&partnerID=40&md5=534d8edeab9f988ffc4add4bf35c4b7e","The Middle East and North Africa (MENA), primarily the Arabian Peninsula (AP), is a region where the rate of mean surface temperature rise per decade is among the highest globally known during the recent past. Moreover, MENA regional climate is very sensitive to internal and external climate drivers. Therefore, it is of significant practical importance to analyze MENA sensitivity to climate trends as well as leading variability modes such as El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Indian summer monsoon (ISM). Using multiple regression technique on observations and the high-resolution atmospheric model output, this study investigates the role of climate trends and leading circulation modes such as NAO, ENSO, and ISM in inducing temperature and precipitation variability in MENA region for the period 1979–2008. Our results show substantial regional temperature and precipitation responses of ENSO, NAO, and ISM over MENA. Both the model and the observations indicate that positive phase of NAO and ENSO significantly cools central parts of MENA, in particular, the AP in winter. However, in boreal summer, the warm ENSO phase produces significant warming and drying over the tropical region. The strengthening (weakening) of ISM suggests cooling (warming) and wetting (drying) over MENA rain-belt region. Moreover, ISM induces a dipole precipitation structure over the tropics caused by Intertropical Convergence Zone shift and associated cloud distribution. High-resolution atmospheric model slightly underestimates NAO and ENSO winter cooling over the AP; however, overall patterns are well reproduced. The conducted analysis sheds light on the internal mechanisms of MENA climate variability. ©2018. American Geophysical Union. All Rights Reserved." "57192409878;24472698700;23493268700;6603581315;","Impact of Convective Activity on Precipitation δ18O in Isotope-Enabled General Circulation Models",2018,"10.1029/2018JD029187","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058185304&doi=10.1029%2f2018JD029187&partnerID=40&md5=41bdb96f5f93df0f7bf2878a556e51e8","The δ18O signal preserved in paleoarchives is widely used to reconstruct past climate conditions. In many speleothems, this signal is classically interpreted via the amount effect. However, recent work has shown that precipitation δ18O (δ18OP) is greatly influenced by convective processes distinct from precipitation amount, and new observations indicate that δ18OP is negatively correlated with the fraction of stratiform precipitation. Isotope-enabled climate models have emerged as a key interpretive tool in water isotope systematics, and it is thus important to determine to what extent they can reproduce these relationships. Here seven isotope-enabled models, including the state-of-the-art model iCAM5, are evaluated to see whether they can simulate the impact of convective activity on δ18OP in observations. The results show that, of these models, only iCAM5 can simulate the observed anticorrelation between stratiform fraction and δ18OP. Furthermore, while all models can simulate the observed relationship between outgoing longwave radiation and δ18OP, different models achieve this via different mechanisms—some getting the right answer for the wrong reasons. Because iCAM5 appears in various metrics to correctly simulate δ18OP variability, we use it to examine long-standing interpretations of δ18OP over Asia. We find that the contribution of convective processes is very site dependent, with local processes accounting for a very small amount of variance at the sites of most Chinese cave records (speleothems). The residual is attributed to source and transport effects. Our results imply that state-of-the-art models like iCAM5 can and should be used to guide the interpretation of δ18OP -based proxies. ©2018. American Geophysical Union. All Rights Reserved." "57200197794;18438062100;6602988199;55512674800;14023953700;35396858200;16834406100;8359591200;6602221672;26039103000;6506458269;26643054400;55894199200;37040691400;57207193883;57203052406;16200107900;56214091200;6603372665;6602356428;24477694300;","Estimating Source Region Influences on Black Carbon Abundance, Microphysics, and Radiative Effect Observed Over South Korea",2018,"10.1029/2018JD029257","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057951214&doi=10.1029%2f2018JD029257&partnerID=40&md5=fd5ab1145a3b11fc24ca2c688d05f83e","East Asia is the strongest global source region for anthropogenic black carbon (BC), the most important light-absorbing aerosol contributing to direct radiative climate forcing. To provide extended observational constraints on regional BC distributions and impacts, in situ measurements of BC were obtained with a single particle soot photometer during the May/June 2016 Korean-United States Air Quality aircraft campaign (KORUS-AQ) in South Korea. Unique chemical tracer relationships were associated with BC sourced from different regions. The extent and variability in vertical BC mass burden for 48 profiles over a single site near Seoul were investigated using back trajectory and chemical tracer analysis. Meteorologically driven changes in transport influenced the relative importance of different source regions, impacting observed BC loadings at all altitudes. Internal mixing and size distributions of BC further demonstrated dependence on source region: BC attributed to China had a larger mass median diameter (180 ± 13 nm) than BC attributed to South Korea (152 ± 25 nm), and BC associated with long-range transport was less thickly coated (60 ± 4 nm) than that sourced from South Korea (75 ± 16 nm). The column BC direct radiative effect at the top of the atmosphere was estimated to be 1.0+0.9 0.5 W/m2, with average values for different meteorological periods varying by a factor of 2 due to changes in the BC vertical profile. During the campaign, BC sourced from South Korea (≤ 31%), China (22%), and Russia (14%) were the most significant single-region contributors to the column direct radiative effect. ©2018. American Geophysical Union. All Rights Reserved." "35227762400;55326237100;55170496500;6701606453;37078354100;57205096472;57205095218;7202252296;6602600408;","Using CALIOP to estimate cloud-field base height and its uncertainty: The Cloud Base Altitude Spatial Extrapolator (CBASE) algorithm and dataset",2018,"10.5194/essd-10-2279-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058554540&doi=10.5194%2fessd-10-2279-2018&partnerID=40&md5=ce1d3ca1568cc10d46a87d9323f8dd41","A technique is presented that uses attenuated backscatter profiles from the CALIOP satellite lidar to estimate cloud base heights of lower-troposphere liquid clouds (cloud base height below approximately 3 km). Even when clouds are thick enough to attenuate the lidar beam (optical thickness τ≥5), the technique provides cloud base heights by treating the cloud base height of nearby thinner clouds as representative of the surrounding cloud field. Using ground-based ceilometer data, uncertainty estimates for the cloud base height product at retrieval resolution are derived as a function of various properties of the CALIOP lidar profiles. Evaluation of the predicted cloud base heights and their predicted uncertainty using a second statistically independent ceilometer dataset shows that cloud base heights and uncertainties are biased by less than 10 %. Geographic distributions of cloud base height and its uncertainty are presented. In some regions, the uncertainty is found to be substantially smaller than the 480m uncertainty assumed in the A-Train surface downwelling longwave estimate, potentially permitting the most uncertain of the radiative fluxes in the climate system to be better constrained. © Author(s) 2018." "57191227191;55717074000;7404544551;55577875600;57201942906;57192212652;57191226379;55438848700;57190497058;","Radiative effect and climate impacts of brown carbon with the Community Atmosphere Model (CAM5)",2018,"10.5194/acp-18-17745-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058503201&doi=10.5194%2facp-18-17745-2018&partnerID=40&md5=c1c68b9796583870529216d870f72f1d","A recent development in the representation of aerosols in climate models is the realization that some components of organic aerosol (OA), emitted from biomass and biofuel burning, can have a significant contribution to shortwave radiation absorption in the atmosphere. The absorbing fraction of OA is referred to as brown carbon (BrC). This study introduces one of the first implementations of BrC into the Community Atmosphere Model version 5 (CAM5), using a parameterization for BrC absorptivity described in Saleh et al. (2014). Nine-year experiments are run (2003-2011) with prescribed emissions and sea surface temperatures to analyze the effect of BrC in the atmosphere. Model validation is conducted via model comparison to single-scatter albedo and aerosol optical depth from the Aerosol Robotic Network (AERONET). This comparison reveals a model underestimation of single scattering albedo (SSA) in biomass burning regions for both default and BrC model runs, while a comparison between AERONET and the model absorption Ångström exponent shows a marked improvement with BrC implementation. Global annual average radiative effects are calculated due to aerosol-radiation interaction (REari; 0:13±0:01Wm -2 ) and aerosol-cloud interaction (REaci; 0:01±0:04Wm -2 ). REari is similar to other studies' estimations of BrC direct radiative effect, while REaci indicates a global reduction in low clouds due to the BrC semidirect effect. The mechanisms for these physical changes are investigated and found to correspond with changes in global circulation patterns. Comparisons of BrC implementation approaches find that this implementation predicts a lower BrC REari in the Arctic regions than previous studies with CAM5. Implementation of BrC bleaching effect shows a significant reduction in REari (0:06±0:008Wm -2 ). Also, variations in OA density can lead to differences in REari and REaci, indicating the importance of specifying this property when estimating the BrC radiative effects and when comparing similar studies. © Author(s) 2018." "54397207800;36342344200;55705441800;6701754792;17346297200;","A 17 year climatology of the macrophysical properties of convection in Darwin",2018,"10.5194/acp-18-17687-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058574871&doi=10.5194%2facp-18-17687-2018&partnerID=40&md5=14c077c05ba618d4b830f319bc2b2c1d","The validation of convective processes in global climate models (GCMs) could benefit from the use of large datasets that provide long-Term climatologies of the spatial statistics of convection. To that regard, echo top heights (ETHs), convective areas, and frequencies of mesoscale convective systems (MCSs) from 17 years of data from a C-band polarization (CPOL) radar are analyzed in varying phases of the Madden-Julian Oscillation (MJO) and northern Australian monsoon in order to provide ample validation statistics for GCM validation. The ETHs calculated using velocity texture and reflectivity provide similar results, showing that the ETHs are insensitive to various techniques that can be used. Retrieved ETHs are correlated with those from cloud top heights retrieved by Multifunctional Transport Satellites (MTSATs), showing that the ETHs capture the relative variability in cloud top heights over seasonal scales.
Bimodal distributions of ETH, likely attributable to the cumulus congestus clouds and mature stages of convection, are more commonly observed when the active phase of the MJO is over Australia due to greater mid-level moisture during the active phase of the MJO. The presence of a convectively stable layer at around 5 km altitude over Darwin inhibiting convection past this level can explain the position of the modes at around 2-4 km and 7-9 km. Larger cells were observed during break conditions compared to monsoon conditions, but only during the inactive phase of the MJO. The spatial distributions show that Hector, a deep convective system that occurs almost daily during the wet season over the Tiwi Islands, and sea-breeze convergence lines are likely more common in break conditions. Oceanic MCSs are more common during the night over Darwin. Convective areas were generally smaller and MCSs more frequent during active monsoon conditions. In general, the MJO is a greater control on the ETHs in the deep convective mode observed over Darwin, with higher distributions of ETH when the MJO is active over Darwin. © Author(s) 2018." "8720897100;55932424000;17433787100;7004935190;14024872700;15519671300;55210952000;26029605900;7004296083;24529241300;6603729297;8871497700;35461255500;55800347700;7006593624;7006599647;","Combined effects of boundary layer dynamics and atmospheric chemistry on aerosol composition during new particle formation periods",2018,"10.5194/acp-18-17705-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058618962&doi=10.5194%2facp-18-17705-2018&partnerID=40&md5=54e0fb2a13300c5daccc80c50bd27c1e","Characterizing aerosol chemical composition in response to meteorological changes and atmospheric chemistry is important to gain insights into new particle formation mechanisms. A BAECC (Biogenic Aerosols - Effects on Clouds and Climate) campaign was conducted during the spring 2014 at the SMEAR II station (Station for Measuring Forest Ecosystem-Aerosol Relations) in Finland. The particles were characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). A PBL (planetary boundary layer) dilution model was developed to assist interpreting the measurement results. Right before nucleation events, the mass concentrations of organic and sulfate aerosol species were both decreased rapidly along with the growth of PBL heights. However, the mass fraction of sulfate aerosol of the total aerosol mass was increased, in contrast to a decrease for the organic mass fraction. Meanwhile, an increase in LVOOA (low-volatility oxygenated organic aerosol) mass fraction of the total organic mass was observed, in distinct comparison to a reduction of SVOOA (semi-volatile OOA) mass fraction. Our results demonstrate that, at the beginning of nucleation events, the observed sulfate aerosol mass was mainly driven by vertical turbulent mixing of sulfate-rich aerosols between the residual layer and the newly formed boundary layer, while the condensation of sulfuric acid (SA) played a minor role in interpreting the measured sulfate mass concentration. For the measured organic aerosols, their temporal profiles were mainly driven by dilution from PBL development, organic aerosol mixing in different boundary layers and/or partitioning of organic vapors, but accurate measurements of organic vapor concentrations and characterization on the spatial aerosol chemical composition are required. In general, the observed aerosol particles by AMS are subjected to joint effects of PBL dilution, atmospheric chemistry and aerosol mixing in different boundary layers. During aerosol growth periods in the nighttime, the mass concentrations of organic aerosols and organic nitrate aerosols were both increased. The increase in SVOOA mass correlated well with the calculated increase in condensed HOMs' (highly oxygenated organic molecules) mass. To our knowledge, our results are the first atmospheric observations showing a connection between increase in SVOOA and condensed HOMs during the nighttime. © 2018 Copernicus GmbH. All rights reserved." "55575158300;56038267100;9846347800;56009507800;57198616562;6603431534;24491934500;19337612500;6701562043;24833810000;24722339600;36076994600;","Marine boundary layer aerosol in the eastern North Atlantic: Seasonal variations and key controlling processes",2018,"10.5194/acp-18-17615-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058547413&doi=10.5194%2facp-18-17615-2018&partnerID=40&md5=ca8224c5f9e7847f38c5212e7f2009ad","The response of marine low cloud systems to changes in aerosol concentration represents one of the largest uncertainties in climate simulations. Major contributions to this uncertainty are derived from poor understanding of aerosol under natural conditions and the perturbation by anthropogenic emissions. The eastern North Atlantic (ENA) is a region of persistent but diverse marine boundary layer (MBL) clouds, whose albedo and precipitation are highly susceptible to perturbations in aerosol properties. In this study, we examine MBL aerosol properties, trace gas mixing ratios, and meteorological parameters measured at the Atmospheric Radiation Measurement Climate Research Facility's ENA site on Graciosa Island, Azores, Portugal, during a 3- year period from 2015 to 2017. Measurements impacted by local pollution on Graciosa Island and during occasional intense biomass burning and dust events are excluded from this study. Submicron aerosol size distribution typically consists of three modes: Aitken (At, diameter Dp <∼ 100 nm), accumulation (Ac, Dp within ∼ 100 to ∼ 300 nm), and larger accumulation (LA, Dp >∼ 300 nm) modes, with average number concentrations (denoted as NAt, NAc, and NLA below) of 330, 114, and 14 cm -3 , respectively. NAt, NAc, and NLA show contrasting seasonal variations, suggesting different sources and removal processes. NLA is dominated by sea spray aerosol (SSA) and is higher in winter and lower in summer. This is due to the seasonal variations of SSA production, in-cloud coalescence scavenging, and dilution by entrained free troposphere (FT) air. In comparison, SSA typically contributes a relatively minor fraction to NAt (10 %) and NAc (21 %) on an annual basis. In addition to SSA, sources of Acmode particles include entrainment of FT aerosols and condensation growth of Aitken-mode particles inside the MBL, while in-cloud coalescence scavenging is the major sink of NAc. The observed seasonal variation of NAc, being higher in summer and lower in winter, generally agrees with the steady-state concentration estimated from major sources and sinks. NAt is mainly controlled by entrainment of FT aerosol, coagulation loss, and growth of Aitken-mode particles into the Ac-mode size range. Our calculation suggests that besides the direct contribution from entrained FT Ac-mode particles, growth of entrained FT Aitken-mode particles in the MBL also represent a substantial source of cloud condensation nuclei (CCN), with the highest contribution potentially reaching 60% during summer. The growth of Aitken-mode particles to CCN size is an expected result of the condensation of sulfuric acid, a product from dimethyl sulfide oxidation, suggesting that ocean ecosystems may have a substantial influence on MBL CCN populations in the ENA. © Author(s) 2018." "21233445300;35096299800;35794448200;","Quantifying uncertainty from aerosol and atmospheric parameters and their impact on climate sensitivity",2018,"10.5194/acp-18-17529-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058573867&doi=10.5194%2facp-18-17529-2018&partnerID=40&md5=d5de95d4c8dcfdf5dfbd408b3f873e3a","Climate sensitivity in Earth system models (ESMs) is an emergent property that is affected by structural (missing or inaccurate model physics) and parametric (variations in model parameters) uncertainty. This work provides the first quantitative assessment of the role of compensation between uncertainties in aerosol forcing and atmospheric parameters, and their impact on the climate sensitivity of the Community Atmosphere Model, Version 4 (CAM4). Running the model with prescribed ocean and ice conditions, we perturb four parameters related to sulfate and black carbon aerosol radiative forcing and distribution, as well as five atmospheric parameters related to clouds, convection, and radiative flux. In this experimental setup where aerosols do not affect the properties of clouds, the atmospheric parameters explain the majority of variance in climate sensitivity, with two parameters being the most important: one controlling low cloud amount, and one controlling the timescale for deep convection. Although the aerosol parameters strongly affect aerosol optical depth, their impacts on climate sensitivity are substantially weaker than the impacts of the atmospheric parameters, but this result may depend on whether aerosol-cloud interactions are simulated. Based on comparisons to inter-model spread of other ESMs, we conclude that structural uncertainties in this configuration of CAM4 likely contribute 3 times more to uncertainty in climate sensitivity than parametric uncertainties. We provide several parameter sets that could provide plausible (measured by a skill score) configurations of CAM4, but with different sulfate aerosol radiative forcing, black carbon radiative forcing, and climate sensitivity. © Author(s) 2018." "56536745100;55688930000;24722339600;7004807312;57205097643;","The efficacy of aerosol-cloud radiative perturbations from near-surface emissions in deep open-cell stratocumuli",2018,"10.5194/acp-18-17475-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058517073&doi=10.5194%2facp-18-17475-2018&partnerID=40&md5=d9e794246cedc1a30de495f0c63bc778","Aerosol-cloud radiative effects are determined and quantified in simulations of deep open-cell stratocumuli observed during the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) campaign off the west coast of Chile. The cloud deck forms in a boundary layer 1.5 km deep, with cell sizes reaching 50 km in diameter. Global databases of ship tracks suggest that these linear structures are seldom found in boundary layers this deep. Here, we quantify the changes in cloud radiative properties to a continuous aerosol point source moving along a fixed emission line releasing 1017 particles per second. We show that a spatially coherent cloud perturbation is not evident along the emission line. Yet our model simulates an increase in domain-mean all-sky albedo of 0.05, corresponding to a diurnally averaged cloud radiative effect of 20 W mĝ'2, given the annual mean solar insolation at the VOCALS-REx site. Therefore, marked changes in cloud radiative properties in precipitating deep open cells may be driven by anthropogenic near-surface aerosol perturbations, such as those generated by ships.
Furthermore, we demonstrate that these changes in cloud radiative properties are masked by the naturally occurring variability within the organised cloud field. A clear detection and attribution of cloud radiative effects to a perturbation in aerosol concentrations becomes possible when sub-filtering of the cloud field is applied, using the spatio-Temporal distribution of the aerosol perturbation. Therefore, this work has implications for the detection and attribution of effective cloud radiative forcing in marine stratocumuli, which constitutes one of the major physical uncertainties within the climate system. Our results suggest that ships may sometimes have a substantial radiative effect on marine clouds and albedo, even when ship tracks are not readily visible. © Author(s) 2018."
"38762392200;6603445661;24168241000;9275665400;57190936873;6701347361;","H2SO4-H2O-NH3 ternary ion-mediated nucleation (TIMN): Kinetic-based model and comparison with CLOUD measurements",2018,"10.5194/acp-18-17451-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058480560&doi=10.5194%2facp-18-17451-2018&partnerID=40&md5=b48950a923bf07e5852a6915e00dd114","New particle formation (NPF) is known to be an important source of atmospheric particles that impacts air quality, hydrological cycle, and climate. Although laboratory measurements indicate that ammonia enhances NPF, the physicochemical processes underlying the observed effect of ammonia on NPF are yet to be understood. Here we present a comprehensive kinetically based H2SO4-H2O-NH3 ternary ion-mediated nucleation (TIMN) model that is based on the thermodynamic data derived from both quantum-chemical calculations and laboratory measurements. NH3 was found to reduce nucleation barriers for neutral, positively charged, and negatively charged clusters differently, due to large differences in the binding strength of NH3, H2O, and H2SO4 to small clusters of different charging states. The model reveals the general favor of nucleation of negative ions, followed by nucleation on positive ions and neutral nucleation, for which higher NH3 concentrations are needed, in excellent agreement with Cosmics Leaving OUtdoor Droplets (CLOUD) measurements. The TIMN model explicitly resolves dependences of nucleation rates on all the key controlling parameters and captures the absolute values of nucleation rates as well as the dependence of TIMN rates on concentrations of NH3 and H2SO4, ionization rates, temperature, and relative humidity observed in the well-controlled CLOUD measurements well. The kinetic model offers physicochemical insights into the ternary nucleation process and provides a physics-based approach to calculate TIMN rates under a wide range of atmospheric conditions. © 2018 Copernicus GmbH. All rights reserved."
"55823994500;56962915800;56410752500;","Improving seasonal prediction of East Asian Summer rainfall using NESM3.0: Preliminary results",2018,"10.3390/atmos9120487","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058632285&doi=10.3390%2fatmos9120487&partnerID=40&md5=089e7301de5d338fc6b0488d4c297ef8","It has been an outstanding challenge for global climate models to simulate and predict East Asia summer monsoon (EASM) rainfall. This study evaluated the dynamical hindcast skills with the newly developed Nanjing University of Information Science and Technology Earth System Model version 3.0 (NESM3.0). To improve the poor prediction of an earlier version of NESM3.0, we modified convective parameterization schemes to suppress excessive deep convection and enhance insufficient shallow and stratiform clouds. The new version of NESM3.0 with modified parameterizations (MOD hereafter) yields improved rainfall prediction in the northern and southern China but not over the Yangtze River Valley. The improved prediction is primarily attributed to the improvements in the predicted climatological summer mean rainfall and circulations, Nino 3.4 SST anomaly, and the rainfall anomalies associated with the development and decay of El Nino events. However, the MOD still has biases in the predicted leading mode of interannual variability of precipitation. The leading mode captures the dry (wet) anomalies over the South China Sea (northern East Asia) but misplaces precipitation anomalies over the Yangtze River Valley. The model can capture the interannual variation of the circulation indices very well. The results here suggest that, over East Asia land regions, the skillful rainfall prediction relies on not only model's capability in predicting better summer mean and ENSO teleconnection with EASM, but also accurate prediction of the leading modes of interannual variability. © 2018 by the authors."
"56513610900;57201306214;9233214000;6505782676;7402838215;55469200300;","Arctic ice clouds over northern Sweden: Microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI",2018,"10.5194/acp-18-17371-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058149311&doi=10.5194%2facp-18-17371-2018&partnerID=40&md5=b99368d8d043993d4051fe3fc8120d6a","Ice particle and cloud properties such as particle size, particle shape and number concentration influence the net radiation effect of cirrus clouds. Measurements of these features are of great interest for the improvement of weather and climate models, especially for the Arctic region. In this study, balloon-borne in situ measurements of Arctic cirrus clouds have been analysed for the first time with respect to their origin. Eight cirrus cloud measurements have been carried out in Kiruna (68 N), Sweden, using the Balloonborne Ice Cloud particle Imager (B-ICI). Ice particle diameters between 10 and 1200 ?m have been found and the shape could be recognized from 20 ?m upwards. Great variability in particle size and shape is observed. This cannot simply be explained by local environmental conditions. However, if sorted by cirrus origin, wind and weather conditions, the observed differences can be assessed. Number concentrations between 3 and 400 L1 have been measured, but the number concentration has reached values above 100 L1 only for two cases. These two cirrus clouds are of in situ origin and have been associated with waves. For all other measurements, the maximum ice particle concentration is below 50 L1 and for one in situ origin cirrus case only 3 L1. In the case of in situ origin clouds, the particles are all smaller than 350 ?m diameter. The PSDs for liquid origin clouds are much broader with particle sizes between 10 and 1200 ?m. Furthermore, it is striking that in the case of in situ origin clouds almost all particles are compact (61 %) or irregular (25 %) when examining the particle shape. In liquid origin clouds, on the other hand, most particles are irregular (48 %), rosettes (25 %) or columnar (14 %). There are hardly any plates in cirrus regardless of their origin. It is also noticeable that in the case of liquid origin clouds the rosettes and columnar particles are almost all hollow. © 2018 Author(s)."
"56457152000;8629713500;7401796996;56722821200;","Evaluation of autoconversion and accretion enhancement factors in general circulation model warm-rain parameterizations using ground-based measurements over the Azores",2018,"10.5194/acp-18-17405-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058287676&doi=10.5194%2facp-18-17405-2018&partnerID=40&md5=a3ee1ad608426104382094bde68191fe","A great challenge in climate modeling is how to parameterize subgrid cloud processes, such as autoconversion and accretion in warm-rain formation. In this study, we use ground-based observations and retrievals over the Azores to investigate the so-called enhancement factors, Eauto and Eaccr, which are often used in climate models to account for the influence of subgrid variance of cloud and precipitation water on the autoconversion and accretion processes. Eauto and Eaccr are computed for different equivalent model grid sizes. The calculated Eauto values increase from 1.96 (30 km) to 3.2 (180 km), and the calculated Eaccr values increase from 1.53 (30 km) to 1.76 (180 km). Comparing the prescribed enhancement factors in Morrison and Gettleman (2008, MG08) to the observed ones, we found that a higher Eauto (3.2) at small grids and lower Eaccr (1.07) are used in MG08, which might explain why most of the general circulation models (GCMs) produce too-frequent precipitation events but with too-light precipitation intensity. The ratios of the rain to cloud water mixing ratio (qr/qc) at Eaccr D 1:07 and Eaccr D 2:0 are 0.063 and 0.142, respectively, from observations, further suggesting that the prescribed value of Eaccr D 1:07 used in MG08 is too small to simulate precipitation intensity correctly. Both Eauto and Eaccr increase when the boundary layer becomes less stable, and the values are larger in precipitating clouds (CLWP > 75 gm2/ than those in non-precipitating clouds (CLWP < 75 gm2). Therefore, the selection of Eauto and Eaccr values in GCMs should be regime-and resolution-dependent. © 2018 SPIE. All rights reserved."
"56591911900;36765332800;56080932300;54410299300;25626008100;","Earth's surface mass transport derived from GRACE, evaluated by GPS, ICESat, hydrological modeling and altimetry satellite orbits",2018,"10.5194/esurf-6-1203-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058349233&doi=10.5194%2fesurf-6-1203-2018&partnerID=40&md5=296bf99185c2a873116b2b000b1c088f","The Gravity Recovery and Climate Experiment (GRACE) delivered the most accurate quantification of global mass variations with monthly temporal resolution on large spatial scales. Future gravity missions will take advantage of improved measurement technologies, such as enhanced orbit configurations and tracking systems, as well as reduced temporal aliasing errors. In order to achieve the latter, sub-monthly to daily innovative models are computed. In addition, non-conventional methods based on radial basis functions (RBFs) and mascons will give the ability to compute models in regional and global representations as well. We show that the RBF modeling technique can be used for processing GRACE data yielding global gravity field models which fit independent reference values at the same level as commonly accepted global geopotential models based on spherical harmonics. The present study compares for the first time a complete global series of solutions in order to quantify recent ice mass changes. We further compare the ice-induced crustal deformations due to the dynamic loading of the crustal layer with the Global Positioning System (GPS) uplift measurements along Greenland's coastline. Available mass change estimates based on Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry measurements both in Greenland and Antarctica are used to assess the GRACE results. A comparison of GRACE time series with hydrological modeling for various basin extensions reveals overall high correlation to surface and groundwater storage compartments. The forward computation of satellite orbits for altimetry satellites such as Envisat, Jason-1 and Jason-2 compares the performance of GRACE time-variable gravity fields with models including time variability, such as EIGEN-6S4. © 2018 Systematic and Applied Acarology Society. All rights reserved."
"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)."
"37056101400;6602087140;55554531900;12645353200;9044746800;7003334425;7006252685;55390690800;55730541100;6603912161;55226243300;55783064400;7006235542;7006377579;7006837187;57195257572;21933618400;57189089842;6602080205;8404544300;","Coarse-mode mineral dust size distributions, composition and optical properties from AER-D aircraft measurements over the tropical eastern Atlantic",2018,"10.5194/acp-18-17225-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058557641&doi=10.5194%2facp-18-17225-2018&partnerID=40&md5=60c70a3d97cb9c60cab2a87dd8deeb85","Mineral dust is an important component of the climate system, affecting the radiation balance, cloud properties, biogeochemical cycles, regional circulation and precipitation, as well as having negative effects on aviation, solar energy generation and human health. Dust size and composition has an impact on all these processes. However, changes in dust size distribution and composition during transport, particularly for coarse particles, are poorly understood and poorly represented in climate models. Here we present new in situ airborne observations of dust in the Saharan Air Layer (SAL) and the marine boundary layer (MBL) at the beginning of its transatlantic transport pathway, from the AERosol Properties-Dust (AER-D) fieldwork in August 2015, within the peak season of North African dust export. This study focuses on coarse-mode dust properties, including size distribution, mass loading, shape, composition, refractive indices and optical properties. Size distributions from 0.1 to 100 μm diameter (d) are presented, fully incorporating the coarse and giant modes of dust. Within the MBL, mean effective diameter (deff) and volume median diameter (VMD) were 4.6 and 6.0 μm respectively, giant particles with a mode at 20-30 μm were observed, and composition was dominated by quartz and alumino-silicates at d > 1 μm. Within the SAL, particles larger than 20 μm diameter were always present up to 5 km altitude, in concentrations over 10-5 cmg3 constituting up to 40 % of total dust mass. Mean deff and VMD were 4.0 and 5.5 μm respectively. Larger particles were detected in the SAL than can be explained by sedimentation theory alone. Coarse-mode composition was dominated by quartz and alumino-silicates; the accumulation mode showed a strong contribution from sulfate-rich and sea salt particles. In the SAL, measured single scattering albedos (SSAs) at 550 nm representing d < 2.5 μm were 0.93 to 0.98 (mean 0.97). Optical properties calculated for the full size distribution (0.1 < d < 100 μm) resulted in lower SSAs of 0.91-0.98 (mean 0.95) and mass extinction coefficients of 0.27-0.35 m2 g-1 (mean 0.32 m2 g-1). Variability in SSA was mainly controlled by variability in dust composition (principally iron) rather than by variations in the size distribution, in contrast with previous observations over the Sahara where size is the dominant influence. It is important that models are able to capture the variability and evolution of both dust composition and size distribution with transport in order to accurately represent the impacts of dust on climate. These results provide a new SAL dust dataset, fully representing coarse and giant particles, to aid model validation and development. © 2018 Author(s)."
"7103010662;56043294300;","Technology for Sustainable Urban Food Ecosystems in the Developing World: Strengthening the Nexus of Food–Water–Energy–Nutrition",2018,"10.3389/fsufs.2018.00084","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077605514&doi=10.3389%2ffsufs.2018.00084&partnerID=40&md5=45a2600d2063cb14b1c2bc09c57b2c52","Smart integration of technology can help create sustainable urban food ecosystems (UFEs) for the rapidly expanding urban population in the developing world. Technology, especially recent advances in digital-enabled devices based on internet connectivity, are essential for building UFEs at a time when food production is increasingly limited on a global scale by the availability of land, water, and energy. By 2050, two-thirds of the world will be urban—and most of the net world population growth will occur in urban regions in the developing world. A food crisis is looming, with the developing world ill-prepared to sustainably feed itself. We identify 12 innovative technology platforms to advance the UFEs of the developing world: (1) connectivity—information delivery and digital technology platforms; (2) uberized services; (3) precision agriculture (GPS, IoT—Internet of things, AI—artificial intelligence, sensing technology); (4) CEA—controlled environment agriculture, including vertical farms; (5) blockchain for greater transparency, food safety, and identification; (6) solar and wind power connected to microgrids; (7) high-quality, enhanced seeds for greater yield, nutrition, climate, and pest resistance; (8) advanced genetics, including gene editing, synthetic biology, and cloud biology; (9) biotechnology, including microbiome editing, soil biologicals, cultured meat, alternative proteins to meat and dairy; (10) nanotechnology and advanced materials; (11) 3-D printing/additive manufacturing; and (12) integration of new tech to scale-up underutilized, existing technologies. The new tech-enabled UFEs, linked to value-chains, will create entrepreneurial opportunities—and more efficiently use resources and people to connect the nexus of food, water, energy, and nutrition. © Copyright © 2018 Davies and Garrett."
"24449309500;57209466846;","MODIS satellite data evaluation for sand and dust storm monitoring in Saudi Arabia",2018,"10.1080/01431161.2018.1488293","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049574524&doi=10.1080%2f01431161.2018.1488293&partnerID=40&md5=ad81f1a777de5133ece7c4bff4aa0da7","The impacts of wind-blown desert sand and dust are a major concern of environmental and climate study due to their global extent. This article investigates the sand and dust storms detection in Saudi Arabia using Moderate Resolution Imaging Spectroradiometer (MODIS) data, both from Terra and Aqua satellite systems for the years 2002–2011. Normalized Difference Dust Index (NDDI) is applied for the detection of sand and dust storms whilst MODIS band 31 is applied to discriminate atmospheric sand and dust from that present on the ground. In addition, the data from Meteosat satellite, AERONET station, and meteorological stations are used to validate NDDI-based sand and dust storm events. The results of the study show that NDDI can successfully identify and differentiate sand and dust storms from clouds whilst MODIS band 31 can discriminate aerial and surface sand and dust over Saudi Arabia. The results also show that the multi-source data, that is MODIS, Meteosat, AERONET, and meteorological stations, can be very valuable for tracking sand and dust storm events. As no such attempt in the past has been made in Saudi Arabia, it is envisaged that the results of this study will be helpful in planning remote-sensing data for the climate change study in the region. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group."
"57202233697;36492521200;55796534100;57202238020;57202233792;","Development of a forest canopy height estimation model using GLAS full waveform data over sloping terrain",2018,"10.1080/01431161.2018.1506181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052091800&doi=10.1080%2f01431161.2018.1506181&partnerID=40&md5=e495931803a6a024c6b165bae0aa047c","The accurate estimation of forest canopy height is important because it leads to increased accuracy in the estimation of biomass, which is used in the study of the global carbon cycle, forest productivity, and climate change. However, there is no well-developed model that accurately estimates canopy height over undulating land. This paper describes the development of a back-propagation (BP) neural network model that estimates forest canopy height more accurately than other types of model. For modeling purposes, the land in the study area was classified as either plain (low relief areas) or hilly (high relief areas). Four different slope partition thresholds (5°, 10°, 15°, and 20°) were tested to determine the most suitable boundary value. ICESat-GLAS data provided by the Geoscience Laser Altimeter System (GLAS) aboard the Ice, Cloud and Land Elevation Satellite (ICESat), field survey data, and digital elevation model (DEM) data were collected and refined, and various parameters, including waveform extent and topographic index, were calculated. A BP neural network model was created to estimate forest canopy height. Two other models were also developed, one using the topographic index and the other using multiple linear regression, for comparison with the BP neural network model. After calibration, the three models were tested to assess the accuracy of the estimates. The results showed that the BP model estimated canopy height more accurately than the other two models. The use of a 10° boundary to partition the topography into low relief areas and high relief areas improved the accuracy of each model; using the 10° slope boundary, the coefficient of correlation r between the estimates given by the BP neural network model and the field-measured data increased from 0.89 to 0.95 and the Root Mean Square Error (RMSE) decreased from 1.01 to 0.73 m. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group."
"55838659500;28367935500;6603422104;7004060399;","Model uncertainty in cloud-circulation coupling, and cloud-radiative response to increasing CO2, linked to biases in climatological circulation",2018,"10.1175/JCLI-D-17-0665.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058186453&doi=10.1175%2fJCLI-D-17-0665.1&partnerID=40&md5=17a5ae6834dc10e42400c0c21d41b441","Recent analyses of global climate models suggest that uncertainty in the coupling between midlatitude clouds and the atmospheric circulation contributes to uncertainty in climate sensitivity. However, the reasons behind model differences in the cloud-circulation coupling have remained unclear. Here, we use a global climate model in an idealized aquaplanet setup to show that the Southern Hemisphere climatological circulation, which in many models is biased equatorward, contributes to the model differences in the cloud-circulation coupling. For the same poleward shift of the Hadley cell (HC) edge, models with narrower climatological HCs exhibit stronger midlatitude cloud-induced shortwave warming than models with wider climatological HCs. This cloud-induced radiative warming results predominantly from a subsidence warming that decreases cloud fraction and is stronger for narrower HCs because of a larger meridional gradient in the vertical velocity. A comparison of our aquaplanet results with comprehensive climate models suggests that about half of the model uncertainty in the midlatitude cloud-circulation coupling stems from this impact of the circulation on the large-scale temperature structure of the atmosphere, and thus could be removed by improving the climatological circulation in models. This illustrates how understanding of large-scale dynamics can help reduce uncertainty in clouds and their response to climate change. © 2018 American Meteorological Society."
"57203860389;57210687618;7004247643;","Suppression of cold weather events over high-latitude continents in warm climates",2018,"10.1175/JCLI-D-18-0129.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057127363&doi=10.1175%2fJCLI-D-18-0129.1&partnerID=40&md5=26f41f2ca04064ef5480f8a187f5115c","Recent studies, using Lagrangian single-column atmospheric models, have proposed that in warmer climates more low clouds would form asmaritime airmasses advect intoNorthernHemisphere high-latitude continental interiors during winter (DJF). This increase in low cloud amount and optical thickness could reduce surface radiative cooling and suppressArctic air formation events, partly explaining both the warmwinter high-latitude continental interior climate and frost-intolerant species found there during the Eocene and the positive lapserate feedback in future Arctic climate change scenarios. Here the authors examine the robustness of this lowcloud mechanism in a three-dimensional atmospheric model that includes large-scale dynamics. Different warming scenarios are simulated under prescribed CO2 and sea surface temperature, and the sensitivity of winter temperatures and clouds over high-latitude continental interior to mid- and high-latitude sea surface temperatures is examined. Model results show that winter 2-m temperatures on extreme cold days increase about 50% faster than the winter mean temperatures and the prescribed SST. Low cloud fraction and surface longwave cloud radiative forcing also increase in both the winter mean state and on extreme cold days, consistent with previous Lagrangian air-mass studies, but with cloud fraction increasing for different reasons than proposed by previous work. At high latitudes, the cloud longwave warming effect dominates the shortwave cooling effect, and the net cloud radiative forcing at the surface tends to warm high-latitude land but cool midlatitude land. This could contribute to the reducedmeridional temperature gradient in warmer climates and help explain the greater warming of winter cold extremes relative to winter mean temperatures. © 2018 American Meteorological Society."
"51864663400;23991212200;7004479957;55232897900;6602878057;6701346974;55544607500;","Insensitivity of the Cloud Response to Surface Warming Under Radical Changes to Boundary Layer Turbulence and Cloud Microphysics: Results From the Ultraparameterized CAM",2018,"10.1029/2018MS001409","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058702303&doi=10.1029%2f2018MS001409&partnerID=40&md5=3632887d08c1d53eac968ed95a206f7c","We study the cloud response to a +4K surface warming in a new multiscale climate model that uses enough interior resolution to begin explicitly resolving boundary layer turbulence (i.e., ultraparameterization or UP). UP's predictions are compared against those from standard superparameterization (SP). The mean cloud radiative effect feedback turns out to be remarkably neutral across all of our simulations, despite some radical changes in both cloud microphysical parameter settings and cloud-resolving model grid resolution. The overall low cloud response to warming is a positive low cloud feedback over land, a negative feedback (driven by cloud optical depth increase) at high latitudes, and weak feedback over the low-latitude oceans. The most distinct effects of UP result from tuning decisions impacting high-latitude cloud feedback. UP's microphysics is tuned to optimize the model present-day, top-of-atmosphere radiation fluxes against CERES observations, by lowering the cloud ice-liquid phase shift temperature ramp, adjusting the ice/liquid autoconversion rate, and increasing the ice fall speed. This reduces high-latitude low cloud amounts and damps the optical depth feedback at high latitudes, leading to a slightly more positive global cloud feedback compared to SP. A sensitivity test that isolates these microphysical impacts from UP's grid resolution confirms that the microphysical settings are mostly responsible for the differences between SP and UP cloud feedback. ©2018. The Authors."
"7202145115;57189358034;57194193480;8882641700;","The Life Cycle and Net Radiative Effect of Tropical Anvil Clouds",2018,"10.1029/2018MS001484","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058220281&doi=10.1029%2f2018MS001484&partnerID=40&md5=c2d65a11d89e4cb1068c3c11944d3f82","We explore the importance of the life cycle of detrained tropical anvil clouds in producing a weak net cloud radiative effect (NCRE) by tropical convective systems. We simulate a horizontally homogeneous elevated ice cloud in a 2-D framework using the System for Atmospheric Modeling cloud-resolving model. The initially thick cloud produces a negative NCRE, which is later canceled by a positive NCRE as the cloud thins and rises. Turning off interactive cloud radiation reveals that cloud radiative heating and in-cloud convection are fundamental in driving net radiative neutrality. In-cloud convection acts to thin initially thick anvil clouds and loft and maintain thin cirrus. The maintenance of anvil clouds is tied to the recycling of water vapor and cloud ice through sublimation, nucleation, and deposition as air parcels circulate vertically within the cloud layer. Without interactive radiation, the cloud sediments and sublimates away, producing a large negative NCRE. The specification of cloud microphysics substantially influences the cloud's behavior and life cycle, but the tendency of the life cycle to produce compensating cloud radiative effects is robust to substantial changes in the microphysics. Our study shows that small-scale processes within upper level ice clouds likely have a strong influence on the NCRE associated with tropical convective cloud systems. ©2018. The Authors."
"55969140000;55948466000;55247565600;14625770800;","Integration of cloud top heights retrieved from FY-2 meteorological satellite, radiosonde, and ground-based millimeter wavelength cloud radar observations",2018,"10.1016/j.atmosres.2018.07.025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051680726&doi=10.1016%2fj.atmosres.2018.07.025&partnerID=40&md5=d28549188a1bf0b66b21a2de1b68e295","Cloud top height (CTH) is an important parameter monitored in atmospheric observations, which has a significant impact on weather prediction, climate models, and flight services. CTH is typically obtained via three ways, namely, satellite, radiosonde, and ground-based radar, with their corresponding strengths and weaknesses. Traditionally, many studies have focused on independent comparison and analysis of CTHs retrieved from different observations. The researches on how to improve the reliability of the CTH by integrating multiple cloud measurements are rare in the literature despite the significance of this strategy to practical meteorological forecast and disaster prevention improvement. An integration technique of different CTHs retrieved from Fengyun 2 (FY-2) meteorological satellite, radiosonde, and ground-based millimeter wavelength cloud radar observations by using Bayesian decision theory is proposed in this study. A dataset is collected in Beijing, China for 12 months from June 2015 to May 2016 to validate the integration effect. Experimental results show that the integration observations improve the accuracy of single observations. Integration observations are more closely correlated with “true” CTH observations than the single observations. These all show the effectiveness of the proposed multiple source data integration strategy. © 2018"
"6701346974;7006184606;","Intraseasonal variability in a cloud-permitting near-global equatorial aquaplanet model",2018,"10.1175/JAS-D-18-0152.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059253113&doi=10.1175%2fJAS-D-18-0152.1&partnerID=40&md5=49568b2b0331865ab7625998596f3cba","Recent studies have suggested that the Madden-Julian oscillation is a result of an instability driven mainly by cloud-radiation feedbacks, similar in character to self-aggregation of convection in nonrotating, cloud-permitting simulations of radiative-convective equilibrium (RCE). Here we bolster that inference by simulating radiative-convective equilibrium states on a rotating sphere with constant sea surface temperature, using the cloud-permitting System for Atmospheric Modeling (SAM) with 20-km grid spacing and extending to walls at 46° latitude in each hemisphere. Mechanism-denial experiments reveal that cloud-radiation interaction is the quintessential driving mechanism of the simulated MJO-like disturbances, but wind-induced surface heat exchange (WISHE) feedbacks are the primary driver of its eastward propagation. WISHE may also explain the faster Kelvin-like modes in the simulations. These conclusions are supported by a linear stability analysis of RCE states on an equatorial beta plane. © 2018 American Meteorological Society."
"7103246957;7102933062;","Understanding land–atmosphere–climate coupling from the Canadian prairie dataset",2018,"10.3390/environments5120129","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072823577&doi=10.3390%2fenvironments5120129&partnerID=40&md5=78b5c5f49491b04bcf695c4de9af6d62","Analysis of the hourly Canadian Prairie data for the past 60 years has transformed our quantitative understanding of land–atmosphere–cloud coupling. The key reason is that trained observers made hourly estimates of the opaque cloud fraction that obscures the sun, moon, or stars, following the same protocol for 60 years at all stations. These 24 daily estimates of opaque cloud data are of sufficient quality such that they can be calibrated against Baseline Surface Radiation Network data to yield the climatology of the daily short-wave, long-wave, and total cloud forcing (SWCF, LWCF and CF, respectively). This key radiative forcing has not been available previously for climate datasets. Net cloud radiative forcing changes sign from negative in the warm season, to positive in the cold season, when reflective snow reduces the negative SWCF below the positive LWCF. This in turn leads to a large climate discontinuity with snow cover, with a systematic cooling of 10◦C or more with snow cover. In addition, snow cover transforms the coupling between cloud cover and the diurnal range of temperature. In the warm season, maximum temperature increases with decreasing cloud, while minimum temperature barely changes; while in the cold season with snow cover, maximum temperature decreases with decreasing cloud, and minimum temperature decreases even more. In the warm season, the diurnal ranges of temperature, relative humidity, equivalent potential temperature, and the pressure height of the lifting condensation level are all tightly coupled to the opaque cloud cover. Given over 600 station-years of hourly data, we are able to extract, perhaps for the first time, the coupling between the cloud forcing and the warm season imbalance of the diurnal cycle, which changes monotonically from a warming and drying under clear skies to a cooling and moistening under cloudy skies with precipitation. Because we have the daily cloud radiative forcing, which is large, we are able to show that the memory of water storage anomalies, from precipitation and the snowpack, goes back many months. The spring climatology shows the memory of snowfall back through the entire winter, and the memory in summer, goes back to the months of snowmelt. Lagged precipitation anomalies modify the thermodynamic coupling of the diurnal cycle to the cloud forcing, and shift the diurnal cycle of the mixing ratio, which has a double peak. The seasonal extraction of the surface total water storage is a large damping of the interannual variability of precipitation anomalies in the growing season. The large land-use change from summer fallow to intensive cropping, which peaked in the early 1990s, has led to a coupled climate response that has cooled and moistened the growing season, lowering cloud-base, increasing equivalent potential temperature, and increasing precipitation. We show a simplified energy balance of the Prairies during the growing season, and its dependence on reflective cloud. © 2018 by the authors. Licensee MDPI, Basel, Switzerland."
"57210458175;7006729638;7004875378;35616404000;","On the relationship between coral δ13C and Caribbean climate",2018,"10.1002/joc.5772","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052458413&doi=10.1002%2fjoc.5772&partnerID=40&md5=6511a8a7e5d131c319bc220b754aa491","A coral (Orbicella faveolata) δ13C isotope ratio record off the southwest coast of Puerto Rico is used to indicate regional ocean–atmosphere conditions over the 20th century. The coral δ13C record is correlated positively with North Atlantic sea surface temperature (SST) and local evaporation. Spatial correlation maps show a broad area of influence by SST, sea-level pressure and evaporation to the northeast of Puerto Rico. The composite maps reflect a strengthening of the North Atlantic anticyclone and east Pacific counter-currents during years of enhanced coral growth. The coral δ13C record presented here corresponds with a local cloud cover increase of ~10% in parallel with a 0.5 °C rise of local SST since 1900. Environmental conditions tend to lead coral growth in a knock-on effect as seen in local SST, cloud cover and evaporation data. The coral community may thus be a sentinel of both multi-year fluctuations and centennial trends in Central Caribbean climate. © 2018 Royal Meteorological Society"
"26634244600;57191100092;7101931045;6603137309;","Reduced wet-season length detected by satellite retrievals of cloudiness over Brazilian Amazonia: A new methodology",2018,"10.1175/JCLI-D-17-0702.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058174971&doi=10.1175%2fJCLI-D-17-0702.1&partnerID=40&md5=a2e07a0d222fc9a602af0d235c1665f4","This study investigates the variability of the seasonal cycle of convection in the Brazilian Amazon basin during the last decades, and examines physical mechanisms that potentially trigger these modifications. A new methodology to evaluate the onset and length of the rainy season using long-term cloud fraction observations from geostationary satellites is proposed and the connection between cloud cycle variability, surface properties, and thermodynamic and dynamic conditions is explored. The results show that cloud cover has significantly decreased over the last decades. The decline in cloudiness is steeper at 1200 UTC (0800 LT), when a trend of up to -6% decade -1 is observed over the central and eastern Amazon. High-cloud-cover reduction is the major contributor to the observed decline in total cloud fraction. Delayed onsets and a reduction of up to 4 days yr -1 in the northern and central Amazon wet-season length are observed. Correlation analyses indicate that the El Niño phenomenon affects the interannual variability of cloudiness in the Amazon, leading to delayed onset and early demise of the rainy season. The tropical South Atlantic, the Pacific warm pool, and the North Atlantic tripole also play a small, but significant, role in the Amazon's cloudiness variability. The decrease in cloudiness over the Amazon basin reduces the amount of solar radiation reflected back to space while increasing irradiance at the surface. This local warming alters surface heat fluxes and the atmospheric thermodynamic profile, further affecting cloud development. The strong tendencies reported here indicate a significant shift in the Amazonian hydroclimate during the last few decades. © 2018 American Meteorological Society."
"35146805400;7004154626;","ISCCP observed large-scale cloud features over the Indo-Pacific, Southern Annular Mode and Indian summer monsoon",2018,"10.1016/j.polar.2018.04.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046159567&doi=10.1016%2fj.polar.2018.04.008&partnerID=40&md5=f5de8be3ad97c9629aa71c37c3f73bd5","The robustness of southern polar linkages with the Indian Summer Monsoon Rainfall (ISMR) is affirmed by employing the Empirical Orthogonal Function (EOF) analysis on Outgoing Longwave Radiation (OLR) over the Indian region. It is observed that the OLR's primary mode of variability (EOF1), which covers almost the entire country and holds a strong positive relationship with ISMR, is significantly associated with Southern Annular Mode (SAM). The International Satellite Cloud Climatology Project (ISCCP) generated spatial distribution of clouds during the recent three decades prominently displays formation and clustering of clouds over the central Pacific as a manifestation of the ocean-atmosphere coupled interactions associated with negative mode of SAM. Further, the northwest ward progression of the cloud-free patterns from equatorial western Pacific to the Indian region is distinctly evident in the ISCCP classified High-level clouds as compared to Middle and Low clouds during the summer monsoon season, thereby inhibiting its monsoon activity. As such, this study demonstrates an association between the southern hemispheric high latitude mode and cloud dynamics over the Indo-Pacific basin having a potential implication on the performance of Indian monsoon. © 2018 Elsevier B.V. and NIPR"
"57203793097;54894233700;55790233000;6603381720;7006783796;6506234624;24322892500;","Comparison of cloud microphysics schemes in a warn-on-forecast system using synthetic satellite objects",2018,"10.1175/WAF-D-18-0112.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058792390&doi=10.1175%2fWAF-D-18-0112.1&partnerID=40&md5=6fdad4c89a68735a46c8ea9fc7c6a102","Forecasts of high-impact weather conditions using convection-allowing numerical weather prediction models have been found to be highly sensitive to the selection of cloud microphysics scheme used within the system. The Warn-on-Forecast (WoF) project has developed a rapid-cycling, convection-allowing, data assimilation and forecasting system known as the NSSL Experimental WoF System for ensembles (NEWS-e), which is designed to utilize advanced cloud microphysics schemes. NEWS-e currently (2017-18) uses the double-moment NSSL variable density scheme (NVD), which has been shown to generate realistic representations of convective precipitation within the system. However, very little verification on nonprecipitating cloud features has been performed with this system. During the 2017 Hazardous Weather Testbed (HWT) experiment, an overestimation of the areal coverage of convectively generated cirrus clouds was observed. Changing the cloud microphysics scheme to Thompson generated more accurate cloud fields. This research undertook the task of improving the cloud analysis generated by NVD while maintaining its skill for other variables such as reflectivity. Adjustments to cloud condensation nuclei (CCN), fall speed, and collection efficiencies were made and tested over a set of six severe weather cases occurring during May 2017. This research uses an object-based verification approach in which objects of cold infrared brightness temperatures, high cloud-top pressures, and cloud water path are generated from model output and compared against GOES-13 observations. Results show that the modified NVD scheme generated much more skillful forecasts of cloud objects than the original formulation without having a negative impact on the skill of simulated composite reflectivity forecasts. © 2018 American Meteorological Society."
"22236141200;56416709700;57190743768;35811524000;55758572400;57190534239;57189344213;","Characteristics of the planetary boundary layer above Wuhan, China based on CALIPSO",2018,"10.1016/j.atmosres.2018.07.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051019582&doi=10.1016%2fj.atmosres.2018.07.024&partnerID=40&md5=080da8b5376dc3b151a0787e9e5ad38d","Planetary boundary layer height (PBLH) has important implications for human health, weather forecasting, ecology, and climate change. This study aims to investigate the characteristics of the PBLH above Wuhan, China. We propose a new procedure (wavelet covariance and the ideal curve-fitting algorithm) to reveal PBLHs based on the Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO) attenuated backscatter ratio. Under cloud situation, the results of PBLHs revealed from CALIPSO show a relatively low correlation (R2 = 0.55) with PBLHs determined using a thermodynamic method. And the results show a significant correlation coefficient (R2 = 0.86) when the cloudy scenarios are eliminated. Because CALIPSO could have mistakenly classified cloud tops as PBLHs during the formation of stratocumulus clouds. Characteristics of annual and seasonal variations of the PBLH for all sky conditions from June 2006 to September 2013 were also studied. Because of the climatic and geographic characteristics of Wuhan City, the PBLHs display clear annual and seasonal variations. Warmer seasons have deeper PBLHs, while colder seasons are characterized by shallower PBLHs. Over 90% of daytime PBLHs in Wuhan are between 400 and 1800 m, while over 90% of nocturnal PBLHs clustered between 200 m and 1000 m. This research will contribute to improving PBLH input parameters for numerical models and enhance the understanding of the urban planetary boundary layer. © 2018 Elsevier B.V."
"57110426700;8696069500;7201504886;35509639400;","The signature of shallow circulations, not cloud radiative effects, in the spatial distribution of tropical precipitation",2018,"10.1175/JCLI-D-18-0230.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057080349&doi=10.1175%2fJCLI-D-18-0230.1&partnerID=40&md5=9479bd6e2a71850137e0791170a1a50c","Recent research suggests cloud-radiation interaction as key for intermodel differences in tropical precipitation change with warming. This motivates the hypothesis that intermodel differences in the climatology of precipitation, and in its response to warming, should reduce in the absence of cloud-radiation interaction. The hypothesis is explored with the aquaplanet simulations by the Clouds On-Off Klimate Intercomparison Experiment performed by seven general circulation models, wherein atmospheric cloud radiative effects (ACREs) are active (ACRE-on) and inactive (ACRE-off). Contrary to expectation, models' climatology of tropical precipitation are more diverse in the ACRE-off experiments, as measured by the position of the intertropical convergence zone (ITCZ), the subtropical precipitation minima, and the associated organization of the tropical circulation. Also the direction of the latitudinal shift of the ITCZ differs more in simulations with inactive cloud radiative effects. Nevertheless, both in ACRE-on and ACRE-off, the same relationship between tropical precipitation and the mean vertical velocity (zonally, temporally, and vertically averaged) emerges in all models. An analysis framework based on the moist static energy budget and used in the moisture space is then developed to understand what controls the distribution of the mean vertical velocity. The results suggest that intermodel differences in tropical circulation and zonal-mean precipitation patterns are most strongly associated with intermodel differences in the representation of shallow circulations that connect dry and moist regions. © 2018 American Meteorological Society."
"9249239700;8560603600;22635190100;7202899330;57203043665;","Assessment of the cloud liquid water from climate models and reanalysis using satellite observations",2018,"10.3319/TAO.2018.07.04.01","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061985592&doi=10.3319%2fTAO.2018.07.04.01&partnerID=40&md5=5f5ebad747523f0555a6421a9043b06f","We perform a model-observation comparison and report on the state-of-the-art cloud liquid water content (CLWC) and path (CLWP) outputs from the present-day global climate models (GCMs) simulations in CMIP3/CMIP5, two other GCMs (UCLA and GEOS5) and two reanalyses (ECMWF Interim and MERRA) in comparison with two satellites observational datasets (CloudSat and MODIS). We use two different liquid water observation products from CloudSat and MODIS, for CLWP and their combined product for LWC with a method to remove the contribution from precipitating and convective core hydrometeors so that more meaningful model-observation comparisons can be made. Considering the CloudSat’s limitations of CLWC retrievals due to contamination from the precipitation and from radar clutter near the surface, an estimate CLWC is synergistically constructed using MODIS CLWP and CloudSat CLWC. The model-observation comparison shows that most of the CMIP3/CMIP5 annual mean CLWP values are overestimated by factors of 2 - 10 compared to observations globally. There are a number of CMIP5 models, including CSIRO, MPI, and the UCLA GCM that perform well compared to the other models. For the vertical structure of CLWC, significant systematic biases are found with many models biased significantly high above the mid-troposphere. In the tropics, systematic high biases occur at all levels above 700 hPa. Based on the Taylor diagram, the ensemble performance of CMIP5 CLWP simulation shows little or no improvement relative to CMIP3. © 2018 Chinese Geoscience Union. All Rights Reserved."
"57190496636;7005537814;6507559601;16636910800;7004477665;","Modelling the impacts of projected sea ice decline on the low atmosphere and near-surface permafrost on the North Slope of Alaska",2018,"10.1002/joc.5741","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052816727&doi=10.1002%2fjoc.5741&partnerID=40&md5=99c1b6ea1b82ab3341977ec622a55dfb","This model-based study assesses the response of the lower atmosphere and near-surface permafrost on the North Slope of Alaska to projections in sea ice decline. The Weather Research and Forecast model, with polar optimization (polar WRF), was configured for the North Slope of Alaska and the adjacent Arctic Ocean and run for two decade-long control periods, the 1970s and the 2040s. Community Earth System Model output was used to drive the polar WRF model. By swapping the sea ice coverage in the control cases, two polar WRF sensitivity experiments were designed to quantify the changes in the low atmosphere and near-surface permafrost in response to projected declines in sea ice extent. The strongest impacts of sea ice decline occur primarily during the late fall and early winter. These include increases in surface air temperature, surface humidity, total cloud cover, and precipitation amount. Future impacts of sea ice decline are projected to become weaker over time in the late fall and early winter while becoming more prominent in late spring and early summer. Projected sea ice decline also inhibits low-level cloud formation in summer as a result of destabilization of the boundary layer. Sensitivity experiments by polar WRF and Geophysical Institute Permafrost Laboratory model, respectively, suggest that sea ice decline explains approximately 20% of both the atmospheric and permafrost warmings on a mean annual basis compared to the overall projected warming under the RCP4.5 scenario. © 2018 Royal Meteorological Society"
"36705961100;57189186147;57203902703;","Site-dependent growth responses to climate in two major tree species from tropical dry forests of southwest Ecuador",2018,"10.1016/j.dendro.2018.09.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053481018&doi=10.1016%2fj.dendro.2018.09.004&partnerID=40&md5=88f7685db972ddced025940fb5586e79","Tropical dry forests (hereafter TDFs) have been extensively logged and converted into croplands or grasslands worldwide. Tumbesian forests in southwest Ecuador are among the most diverse and endangered TDFs. They face seasonal droughts of varied severity and are also subjected to episodic very wet and cloudy conditions during El Niño events. However, we lack a local quantification of their responses to regional climate (temperature, precipitation, cloud cover) and El Niño which could change across sites. Here we use dendrochronology to quantify the radial-growth rates and the responses to climate (mean temperatures, precipitation amount, cloud cover and drought severity) of two major tree species forming annual rings (Geoffroea spinosa, Handroanthus chrysanthus) in three TDFs with different local climate conditions. The lowest (1.0 mm yr−1) and the highest (2.1 mm yr−1) radial-growth rates of both tree species were found in the hottest-driest and moderately hot sites, respectively. G. spinosa growth responded positively to wet, cool and cloudy conditions in the hottest-driest and moderately hot sites, but the most intense response to drought was observed in the driest site at 1–5 months long scales. H. chrysanthus growth reacted positively to high growing-season precipitation in all sites, particularly in the driest site, and to cloudy conditions in moderately hot sites. The growth of H. chrysanthus was negatively associated to the Southern Oscillation Index in the dry-hot and in the moderately hot sites. Tree species coexisting in TDFs show varied growth responses to regional weather variability, drought severity and El Niño events across sites with different local climate conditions. © 2018 Elsevier GmbH"
"8881618800;8957061500;57191291166;7202127838;36703525500;56151984200;6701727687;","ITCZ trend analysis via Geodesic P-spline smoothing of the AIRWAVE TCWV and cloud frequency datasets",2018,"10.1016/j.atmosres.2018.07.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051135894&doi=10.1016%2fj.atmosres.2018.07.019&partnerID=40&md5=33006f469614f21e0f822428703a1024","The Inter Tropical Convergence Zone (ITCZ) is the region of the Earth's atmosphere where the trade winds converge. This region is characterized by rising air, strong convection, clouds and heavy precipitation and it is tightly related to changes in climate patterns on a global scale. For these reasons assessing the ITCZ migrations is of extreme importance for climate monitoring. This can be achieved through the use of satellite data of different kind. In the last decades several quantities have been used as proxies for this purpose, e.g. infrared radiance measured at the top of atmosphere (TOA), precipitation datasets or vertical and horizontal wind components. In this work the ITCZ position is determined and its time evolution is analysed using the Total Column Water Vapour (TCWV) data, retrieved using the Advanced Infra-Red Water Vapour Estimator algorithm (AIRWAVE). AIRWAVE was developed for the retrieval of the TCWV from the Along Track Scanning Radiometer (ATSR) instrument series, operational from 1991 to 2012. It allows the TCWV retrieval from infra-red channels at 11 and 12 μm exploiting the ATSR nadir and forward viewing geometries, for day/night and cloud-free sea surface scenarios. The information on cloud coverage from ATSRs is used as correlative information in order to expand the ITCZ analysis to land scenes. The TCWV and cloud frequency datasets are analysed with a Geodesic P-spline efficient spatial smoothing method specifically developed to extract information from large datasets. The posterior distribution of the model is considered for identification of the ITCZ both over sea and land with associated uncertainty quantification. The resulting AIRWAVE/cloud frequency monthly fields are analysed to detect trends in the ITCZ latitudinal displacement over the 20 years of the ATSR family lifetime. Results indicate that no significant trends can be detected in the 1991–2012 time period. © 2018 Elsevier B.V."
"7402645443;7004325649;","Probabilistic reasoning about measurements of equilibrium climate sensitivity: combining disparate lines of evidence",2018,"10.1007/s10584-018-2315-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056170030&doi=10.1007%2fs10584-018-2315-y&partnerID=40&md5=175c790d326f7bf96a740512ee248865","Where policy and science intersect, there are always issues of ambiguous and conflicting lines of evidence. Combining disparate information sources is mathematically complex; common heuristics based on simple statistical models easily lead us astray. Here, we use Bayesian Nets (BNs) to illustrate the complexity in reasoning under uncertainty. Data from joint research at Resources for the Future and NASA Langley are used to populate a BN for predicting equilibrium climate sensitivity (ECS). The information sources consist of measuring the rate of decadal temperature rise (DTR) and measuring the rate of percentage change in cloud radiative forcing (CRF), with both the existing configuration of satellites and with a proposed enhanced measuring system. The goal of all measurements is to reduce uncertainty in equilibrium climate sensitivity. Subtle aspects of probabilistic reasoning with concordant and discordant measurements are illustrated. Relative to the current prior distribution on ECS, we show that after 30 years of observing with the current systems, the 2σ uncertainty band for ECS would be shrunk on average to 73% of its current value. With the enhanced systems over the same time, it would be shrunk to 32% of its current value. The actual shrinkage depends on the values actually observed. These results are based on models recommended by the Social Cost of Carbon methodology and assume a Business as Usual emissions path. © 2018, The Author(s)."
"15725009000;57197730628;36926416100;14622582000;36730825100;36835829900;55950878200;36626171700;7004590620;7501383116;7005140378;7004035832;","Tropical forest leaves may darken in response to climate change",2018,"10.1038/s41559-018-0716-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056800209&doi=10.1038%2fs41559-018-0716-y&partnerID=40&md5=0f2ba61f2dec77d57a1f2b5e87a2f663","Tropical forest leaf albedo (reflectance) greatly impacts how much energy the planet absorbs; however; little is known about how it might be impacted by climate change. Here, we measure leaf traits and leaf albedo at ten 1-ha plots along a 3,200-m elevation gradient in Peru. Leaf mass per area (LMA) decreased with warmer temperatures along the elevation gradient; the distribution of LMA was positively skewed at all sites indicating a shift in LMA towards a warmer climate and future reduced tropical LMA. Reduced LMA was significantly (P < 0.0001) correlated with reduced leaf near-infrared (NIR) albedo; community-weighted mean NIR albedo significantly (P < 0.01) decreased as temperature increased. A potential future 2 °C increase in tropical temperatures could reduce lowland tropical leaf LMA by 6–7 g m − 2 (5–6%) and reduce leaf NIR albedo by 0.0015–0.002 units. Reduced NIR albedo means that leaves are darker and absorb more of the Sun’s energy. Climate simulations indicate this increased absorbed energy will warm tropical forests more at high CO 2 conditions with proportionately more energy going towards heating and less towards evapotranspiration and cloud formation. © 2018, The Author(s), under exclusive licence to Springer Nature Limited."
"57193861414;6602356372;57097491100;23976053900;7404454238;56483153400;","Investigating the mechanisms of diurnal rainfall variability over Peninsular Malaysia using the non-hydrostatic regional climate model",2018,"10.1007/s00703-017-0541-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021727670&doi=10.1007%2fs00703-017-0541-x&partnerID=40&md5=e3c81ca3af4e4534bb5bef77d9089be9","This study aims to provide a basis for understanding the mechanisms of diurnal rainfall variability over Peninsular Malaysia by utilising the Non-Hydrostatic Regional Climate Model (NHRCM). The present day climate simulations at 5 km resolution over a period of 20 years, from 1st December 1989 to 31st January 2010 were conducted using the six-hourly Japanese re-analysis 55 years (JRA-55) data and monthly Centennial in situ Observation Based Estimates (COBE) of sea surface temperature as lateral and lower boundary conditions. Despite some biases, the NHRCM performed reasonably well in simulating diurnal rainfall cycles over Peninsular Malaysia. During inter-monsoon periods, the availability of atmospheric moisture played a major role in modulating afternoon rainfall maxima over the foothills of the Titiwangsa mountain range (FT sub-region). During the southwest monsoon, a lack of atmospheric moisture inhibits the occurrence of convective rainfall over the FT sub-region. The NHRCM was also able to simulate the suppression of the diurnal rainfall cycle over the east coast of Peninsular Malaysia (EC sub-region) and afternoon rainfall maximum over the Peninsular Malaysia inland-valley (IN sub-region) area during the northeast monsoon. Over the EC sub-region, daytime radiational warming of the top of clouds enhanced atmospheric stability, thus reducing afternoon rainfall. On the other hand, night-time radiational cooling from cloud tops decreases atmospheric stability and increases nocturnal rainfall. In the early morning, the rainfall maximum was confined to the EC sub-region due to the retardation of the north-easterly monsoonal wind by the land breeze and orographic blocking. However, in the afternoon, superimposition of the sea breeze on the north-easterly monsoonal wind strengthened the north-easterly wind, thus causing the zone of convection to expand further inland. © 2017, Springer-Verlag GmbH Austria."
"6603965708;55893616600;7102963655;8204910000;","Climate data records from meteosat first generation part I: Simulation of accurate top-of-atmosphere spectral radiance over pseudo-invariant calibration sites for the retrieval of the in-flight visible spectral response",2018,"10.3390/rs10121959","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058893996&doi=10.3390%2frs10121959&partnerID=40&md5=229169cb9886df9abad7332d895ca6b6","Meteosat First-Generation satellites have acquired more than 30 years of observations that could potentially be used for the generation of a Climate Data Record. The availability of harmonized and accurate a Fundamental Climate Data Record is a prerequisite to such generation. Meteosat Visible and Infrared Imager radiometers suffer from inaccurate pre-launch spectral function characterization and spectral ageing constitutes a serious limitation to achieve such prerequisite. A new method was developed for the retrieval of the pre-launch instrument spectral function and its ageing. This recovery method relies on accurately simulated top-of-atmosphere spectral radiances matching observed digital count values. This paper describes how these spectral radiances are simulated over pseudo-invariant targets such as open ocean, deep convective clouds and bright desert surface. The radiative properties of these targets are described with a limited number of parameters of known uncertainty. Typically, a single top-of-atmosphere radiance spectrum can be simulated with an estimated uncertainty of about 5%. The independent evaluation of the simulated radiance accuracy is also addressed in this paper. It includes two aspects: the comparison with narrow-band well-calibrated radiometers and a spectral consistency analysis using SEVIRI/HRVIS band on board Meteosat Second Generation which was accurately characterized pre-launch. On average, the accuracy of these simulated spectral radiances is estimated to be about ±2%. © 2018 by the authors."
"57202695106;55723405300;44661319600;57204901815;7006421134;57200101288;16162149600;39361982900;8750834400;57199426611;55476297000;9249296100;35168359400;23486850100;47761750600;56478591100;9274820400;13906856500;7003567733;55576176900;11241356400;7402452055;36155758500;36039858000;36155343600;8420354200;","Ultraviolet imager on Venus orbiter Akatsuki and its initial results",2018,"10.1186/s40623-017-0772-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041931056&doi=10.1186%2fs40623-017-0772-6&partnerID=40&md5=c50b3b0ac84ecd947070b37790e65a6a","The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2 and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2 and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing. [Figure not available: see fulltext.]. © 2018, The Author(s)."
"36889113900;","Estimating the impact of artificially injected stratospheric aerosols on the global mean surface temperature in the 21th century",2018,"10.3390/cli6040085","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059357552&doi=10.3390%2fcli6040085&partnerID=40&md5=98e20bb2fadd509740759438e7eb0ed6","In this paper, we apply the optimal control theory to obtain the analytic solutions of the two-component globally averaged energy balance model in order to estimate the influence of solar radiation management (SRM) operations on the global mean surface temperature in the 21st century. It is assumed that SRM is executed via injection of sulfur aerosols into the stratosphere to limit the global temperature increase in the year 2100 by 1.5 °C and keeping global temperature over the specified period (2020-2100) within 2 °C as required by the Paris climate agreement. The radiative forcing produced by the rise in the atmospheric concentrations of greenhouse gases is defined by the Representative Concentration Pathways and the 1pctCO2 (1% per year CO2 increase) scenario. The goal of SRM is formulated in terms of extremal problem, which entails finding a control function (the albedo of aerosol layer) that minimizes the amount of aerosols injected into the upper atmosphere to satisfy the Paris climate target. For each climate change scenario, the optimal albedo of the aerosol layer and the corresponding global mean surface temperature changes were obtained. In addition, the aerosol emission rates required to create an aerosol cloud with optimal optical properties were calculated. © 2018 by the authors."
"57208510232;36243866100;56180140800;9737355300;","Atmospheric scene classification using CALIPSO spaceborne lidar measurements in the Middle East and North Africa (MENA), and India",2018,"10.1016/j.jag.2018.07.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064979806&doi=10.1016%2fj.jag.2018.07.017&partnerID=40&md5=f0b2ded8653fe438e119e17a78456622","This paper presents a new algorithm based on the support vector machine (SVM) for classifying the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) data into classes of clean air, cloud, thin aerosol, dense aerosol, surface, subsurface and totally attenuated. The procedure is as follows: At first, the considered features based on CALIPSO data are prepared. Brightness Temperature Differences between 10 and 12 μm (BTD11-12) is then used to better discriminate dense aerosols from clouds. The particle density feature proposed in this research is another feature participating in the classification. Training samples are automatically extracted by applying strict thresholds on the features. A wrapper feature selection is performed to rank the features based on their performance. Four post-processing steps are implemented to correct some misclassified cells e.g. edges of clouds and high-level clouds. The proposed algorithm was implemented on 4 datasets in the Middle East and North Africa (MENA), and India with various types and densities of aerosol. An accuracy assessment based on the comparison between the obtained results and ground truth samples indicated 0.94, 0.96 4, 0.92 and 0.89 kappa coefficients for the datasets. A statistical hypothesis test demonstrated that our SVM classification overcame CALIPSO vertical feature mask (VFM) product. The experimental result indicates the high accuracy of the proposed algorithm for the atmosphere scene classification using CALIPSO data. © 2018 Elsevier B.V."
"57034069700;35509639400;","On the Interplay Between Convective Aggregation, Surface Temperature Gradients, and Climate Sensitivity",2018,"10.1029/2018MS001406","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058690710&doi=10.1029%2f2018MS001406&partnerID=40&md5=22e521dae65d78317cb87a9ba0c433ad","This study explores the extent to which convective aggregation interacts with sea surface temperature (SST) and affects climate sensitivity. For this purpose, radiative-convective equilibrium simulations are run with a general circulation model coupled to an ocean mixed layer, and several types of perturbations are imposed to the ocean-atmosphere system. Convective aggregation turns out to be much more sensitive to temperature in coupled experiments than in prescribed SST experiments. But changes in convective aggregation induced by a doubling of the CO 2 concentration are always smaller than changes associated with the transition from a non-aggregated to an aggregated state. If aggregation changes were acting alone, they would exert a strong negative feedback on global mean surface temperature. However, in a coupled framework, aggregation changes interact with the SST and generate SST gradients that strengthen the positive low-cloud feedback associated with changes in SST pattern. This overcompensates the negative feedback due to aggregation changes and leads to a larger equilibrium climate sensitivity than in the absence of SST gradients. Although this effect might be model specific, interactions between convective aggregation and the spatial distribution of SST appear crucial to assess the impact of convective aggregation on climate sensitivity. ©2018. The Authors."
"55711668600;9249627300;36739413000;7202079615;","Response of the atmospheric hydrological cycle over the tropical Asian monsoon regions to anthropogenic aerosols and its seasonality",2018,"10.1186/s40645-018-0197-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052095174&doi=10.1186%2fs40645-018-0197-2&partnerID=40&md5=e77061b7924792679409a0afbe9c5db2","This study investigates the impact of anthropogenic aerosols on the atmospheric hydrological cycle over the tropical Asian monsoon region (South Asian, Southeast Asian, and western North Pacific monsoons), using a coupled atmosphere-ocean global climate model (CGCM), Model for Interdisciplinary Research on Climate-Earth System Models. Three-ensemble historical (HIST) and sensitivity (piAERO) experiments for the period 1985–2005 are conducted. The piAERO experiment is the same as HIST, but with anthropogenic aerosol emissions kept at preindustrial values. The results show that, as a whole, the Asian monsoon precipitation is reduced by the increase in aerosol loading during boreal summer and winter. This decrease in precipitation corresponds to a decrease in precipitable water due to the cooling in surface air temperature (SAT), mainly over adjacent oceans. The cooling is explained by the sum of the direct and indirect effects of aerosols. A modulation of the Walker circulation occurs, which can be explained by the east-west horizontal SAT gradient over the tropics due to the spatially heterogeneous increase in aerosols. Concurrent with the modulation of the Walker circulation, the anomalous descending motions over the tropical Asian monsoon region are consistent with the decrease in precipitation. In addition, the changes in local Hadley circulation (or a shift of the inter-tropical convergence zone) are unclear over the Asian monsoon region and thus cannot explain the decrease in precipitation. Moreover, the detailed spatial pattern of the response of the atmospheric hydrological cycle over the Asian monsoon region has distinct seasonality. Interestingly, signals are distinct in regions where tropical disturbance activity is vigorous during both boreal summer and winter. However, uncertainties regarding aerosol-cloud-precipitation interactions in current climate models and internal variability in the climate models may have affected the results.[Figure not available: see fulltext.]. © 2018, The Author(s)."
"57104690900;35209683700;7406523040;7408519295;","A process-based decomposition of decadal-scale surface temperature evolutions over East Asia",2018,"10.1007/s00382-017-3872-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028774282&doi=10.1007%2fs00382-017-3872-x&partnerID=40&md5=a654ccc49d4e811dc5c065ebaed032ca","This study partitions the observed decadal evolution of surface temperature and surface temperature differences between two decades (early 2000s and early 1980s) over the East Asian continent into components associated with individual radiative and non-radiative (dynamical) processes in the context of the coupled atmosphere-surface climate feedback-response analysis method (CFRAM). Rapid warming in this region occurred in late 1980s and early 2000s with a transient pause of warming between the two periods. The rising CO2 concentration provides a sustained, region-wide warming contribution and surface albedo effect, largely related to snow cover change, is important for warming/cooling over high-latitude and high-elevation regions. Sensible hear flux and surface dynamics dominates the evolution of surface temperature, with latent heat flux and atmospheric dynamics working against them mostly through large-scale and convective/turbulent heat transport. Cloud via its shortwave effect provides positive contributions to warming over southern Siberia and South China. The longwave effect associated with water vapor change contributes significant warming over northern India, Tibetan Plateau, and central Siberia. Impacts of solar irradiance and ozone changes are relatively small. The strongest year-to-year temperature fluctuation occurred at a rapid warming (1987–1988) and a rapid cooling (1995–1996) period. The pattern of the rapid warming receives major positive contributions from sensible heat flux with changes in atmospheric dynamics, water vapor, clouds, and albedo providing secondary positive contributions, while surface dynamics and latent heat flux providing negative contributions. The signs of the contributions from individual processes to the rapid cooling are almost opposite to those to the rapid warming. © 2017, Springer-Verlag GmbH Germany."
"55342453700;8632802100;56483153400;36844777100;55243231000;","Extreme precipitation linked to temperature over Japan: current evaluation and projected changes with multi-model ensemble downscaling",2018,"10.1007/s00382-017-3866-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030570606&doi=10.1007%2fs00382-017-3866-8&partnerID=40&md5=21fc84d828a7bf27e1d9d1b6477c19ae","Recent studies have revealed that an increase in surface air temperature elevates the intensity of extreme precipitation associated with the increase of water vapor in the atmosphere, according to the principle of the Clausius–Clapeyron (CC) relationship. In this study, (1) we have verified the dependence of extreme precipitation intensity on temperature (CC relationship) under current climate and (2) investigated the projected changes of the CC relationship over Japan by using multi-model ensemble downscaling experiments of three Regional Climate Models (RCMs) (NHRCM, NRAMS, WRF) forced by JRA25, as well as three General Circulation Models (GCMs) (CCSM4, MIROC5, MRI-CGCM3). Simulated extreme precipitation linked to temperatures from ensemble experiments coincides with observations that place peak temperatures around 19–22 °C. Climate scenarios (RCP4.5) of the late twenty-first century suggest a 2 °C increase of 2 m air temperature, an increase in precipitation intensities above 15 mm/day, and a decrease in weaker precipitation intensities of 10–15 mm/day. The projected change rate of the mean precipitation intensities per mean change in air temperature over Japan is found to be 2.4%/°C. Extreme precipitation intensity increases with temperatures up to 22 °C in future climate scenarios, while the peak is 20 °C for the current climate. Extreme precipitation intensities at higher percentiles are projected to have larger rates of increase (3–5%/°C in the current climate and 4–6%/°C in the future climate scenarios). A decrease of precipitation intensity at higher temperatures relates to water vapor availability. An insufficient water vapor supply for saturation at higher temperatures can lead to a decrease in cloud formation and extreme precipitation. © 2017, The Author(s)."
"57197636789;11940329900;57193882808;36097134700;","Shallow-to-deep transition of continental moist convection: Cold pools, surface fluxes, and mesoscale organization",2018,"10.1175/JAS-D-18-0031.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059266179&doi=10.1175%2fJAS-D-18-0031.1&partnerID=40&md5=829e31e9638c655e65ef4cbf7583c6e1","Large-eddy simulation is used to investigate the effects of cold pools driven by rain evaporation on the shallow-to-deep convection transition over land. The physically consistent methodologies are developed to obtain a time-dependent reference ensemble without cold pools and to apply interactive surface heat fluxes without modeling of surface energy and water budgets. Three different simulation ensembles are contrasted. The reference ensemble, in the spirit of one-dimensional single-column models, eliminates cold pools by horizontally homogenizing negative buoyancy production due to rain evaporation. The additional ensembles complement the reference cold-pool-free ensemble by including cold pools and by applying either interactive or prescribed surface fluxes. Contrasting these ensembles suggests possible improvements of convection parameterization in large-scale models of weather and climate. Without cold pools, the reference ensemble preserves key features of buoyancy-driven cellular convection associated with a field of convective plumes, as assumed in a typical convection parameterization. With cold pools, a significant enhancement of surface heat and moisture fluxes and about an hour delay of their daily maximum is simulated. Cold pools enhance near-surface temperature and moisture standard deviations as well as maxima of the near-surface updraft velocity. They also lead to the reduction of cloud lateral entrainment, deeper vertical development of the cloud layer, and a few-times-larger accumulated surface precipitation. Interactive surface fluxes provide a damping mechanism that noticeably suppresses all these effects. Perhaps surprisingly, cold pools do not significantly change the cloud-base convective mass flux that approximately follows the evolution of surface heat fluxes. © 2018 American Meteorological Society."
"7402820329;55733214300;57205158418;55946208600;56580738900;36018685200;","3D modelling strategy for weather radar data analysis",2018,"10.1007/s12665-018-7985-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058837886&doi=10.1007%2fs12665-018-7985-2&partnerID=40&md5=6336483981d91d8284ea91d523faece2","Weather radar data, which have obvious spatial characteristics, represent an important and essential data source for weather identification and prediction, and the multi-dimensional visualization and analysis of such data in a three-dimensional (3D) environment are important strategies for meteorological assessments of potentially disastrous weather. The previous studies have generally used regular 3D raster grids as a basic structure to represent radar data and reconstruct convective clouds. However, conducting weather radar data analyses based on regular 3D raster grids is time-consuming and inefficient, because such analyses involve considerable amounts of tedious data interpolation, and they cannot be used to address real-time situations or provide rapid-response solutions. Therefore, a new 3D modelling strategy that can be used to efficiently represent and analyse radar data is proposed in this article. According to the mode by which the radar data are obtained, the proposed 3D modelling strategy organizes the radar data using logical objects entitled radar-point, radar-line, radar-sector, and radar-cluster objects. In these logical objects, the radar point is the basic object that carries the real radar data unit detected from the radar scan, and the radar-line, radar-sector, and radar-cluster objects organize the radar-point collection in different spatial levels that are consistent with the intrinsic spatial structure of the radar scan. Radar points can be regarded as spatial points, and their spatial structure can support logical objects; thus, the radar points can be flexibly connected to construct continuous surface data with quads and volume data with hexahedron cells without additional tedious data interpolation. This model can be used to conduct corresponding operations, such as extracting an isosurface with the marching cube method and a radar profile with a designed sectioning algorithm to represent the outer and inner structure of a convective cloud. Finally, a case study is provided to verify that the proposed 3D modelling strategy has a better performance in radar data analysis and can intuitively and effectively represent the 3D structure of convective clouds. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"55344397300;7006306835;55286185400;","Robust responses of the Sahelian hydrological cycle to global warming",2018,"10.1175/JCLI-D-18-0238.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058195817&doi=10.1175%2fJCLI-D-18-0238.1&partnerID=40&md5=a091c9e114e9aa5e5ee41bee38ce8372","How the globally uniform component of sea surface temperature (SST) warming influences rainfall in the African Sahel remains insufficiently studied, despite mean SST warming being among the most robustly simulated and theoretically grounded features of anthropogenic climate change. A prior study using the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) AM2.1 atmospheric general circulation model (AGCM) demonstrated that uniform SST warming strengthens the prevailing northerly advection of dry Saharan air into the Sahel. The present study uses uniform SST warming simulations performed with 7 GFDL and 10 CMIP5 AGCMs to assess the robustness of this drying mechanism across models and uses observations to assess the physical credibility of the severe drying response in AM2.1. In all 17 AGCMs, mean SST warming enhances the free-tropospheric meridional moisture gradient spanning the Sahel and with it the Saharan dry-air advection. Energetically, this is partially balanced by anomalous subsidence, yielding decreased precipitation in 14 of the 17 models. Anomalous subsidence and precipitation are tightly linked across the GFDL models but not the CMIP5 models, precluding the use of this relationship as the start of a causal chain ending in an emergent observational constraint. For AM2.1, cloud-rainfall covariances generate radiative feedbacks on drying through the subsidence mechanism and through surface hydrology that are excessive compared to observations at the interannual time scale. These feedbacks also act in the equilibrium response to uniform warming, calling into question the Sahel's severe drying response to warming in all coupled models using AM2.1. © 2018 American Meteorological Society."
"6602649973;57195927844;6701821355;","Objective definition of climatologically homogeneous areas in the Southern Balkans based on the ERA5 data set",2018,"10.3390/cli6040096","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059439127&doi=10.3390%2fcli6040096&partnerID=40&md5=c1f6371e883c17ed8f24a8b21a708f6b","An objective definition of climatologically homogeneous areas in the southern Balkans is attempted with the use of daily 0.25° × 0.25° ERA5 meteorological data of air temperature, dew point, zonal and meridional wind components, Convective Available Potential Energy, Convective Inhibition, and total cloud cover. The classification of the various grid points into climatologically homogeneous areas is carried out by applying Principal Component Analysis and K-means Cluster Analysis on the mean spatial anomaly patterns of the above parameters for the 10-year period of 2008 to 2017. According to the results, 12 climatologically homogenous areas are found. From these areas, eight are mainly over the sea and four are mainly over the land. The mean intra-annual variations of the spatial anomalies of the above parameters reveal the main climatic characteristics of these areas for the above period. These characteristics refer, for example, to how much warmer or cloudy the climate of a specific area is in a specific season relatively to the rest of the geographical domain. The continentality, the latitude, the altitude, the orientation, and the seasonal variability of the thermal and dynamic factors affecting the Mediterranean region are responsible for the climate characteristics of the 12 areas and the differences among them. © 2018 by the authors."
"57200276826;7003696273;36765524100;","The fast response of the tropical circulation to CO 2 forcing",2018,"10.1175/JCLI-D-18-0086.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058147628&doi=10.1175%2fJCLI-D-18-0086.1&partnerID=40&md5=d40203ea135dab56ee540059eca08591","Atmosphere-only CMIP5 idealized climate experiments with quadrupling of atmospheric CO 2 are analyzed to understand the fast response of the tropical overturning circulation to this forcing and the main mechanism of this response. A new metric for the circulation, based on pressure velocity in the subsidence regions, is defined, taking advantage of the dynamical stability of these regions and their reduced sensitivity to the GCM's cloud and precipitation parameterization schemes. This definition permits us to decompose the circulation change into a sum of relative changes in subsidence area, static stability, and heating rate. A comparative analysis of aqua- and Earth-like planet experiments reveals the effect of the land-sea contrast on the total change in circulation. On average, under the influence of CO 2 increase without surface warming, the atmosphere radiatively cools less, and this drives the 3%-4% slowdown of the tropical circulation. Even in an Earth-like planet setup, the circulation weakening is dominated by the radiatively driven changes in the subsidence regions over the oceans. However, the land-sea differential heating contributes to the vertical pattern of the circulation weakening by driving the vertical expansion of the tropics. It is further found that the surface warming would, independently of the CO 2 effect, lead to up to a 12% slowdown in circulation, dominated by the enhancement of the static stability in the upper troposphere. The two mechanisms identified above combine in the coupled experiment with abrupt quadrupling, causing a circulation slowdown (focused in the upper troposphere) of up to 18%. Here, the independent effect of CO 2 has a considerable impact only at time scales less than one year, being overtaken quickly by the impact of surface warming. © 2018 American Meteorological Society."
"57193427718;55216817200;8241948500;57193423265;","Snow cover monitoring with Chinese Gaofen-4 PMS imagery and the restored snow index (RSI) method: Case studies",2018,"10.3390/rs10121871","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058879810&doi=10.3390%2frs10121871&partnerID=40&md5=15a507404cb75262f40ace6e112c85db","Snow cover is an essential climate variable of the Global Climate Observing System. Gaofen-4 (GF-4) is the first Chinese geostationary satellite to obtain optical imagery with high spatial and temporal resolution, which presents unique advantages in snow cover monitoring. However, the panchromatic and multispectral sensor (PMS) onboard GF-4 lacks the shortwave infrared (SWIR) band, which is crucial for snow cover detection. To reach the potential of GF-4 PMS in snow cover monitoring, this study developed a novel method termed the restored snow index (RSI). The SWIR reflectance of snow cover is restored firstly, and then the RSI is calculated with the restored reflectance. The distribution of snow cover can be mapped with a threshold, which should be adjusted according to actual situations. The RSI was validated using two pairs of GF-4 PMS and Landsat-8 Operational Land Imager images. The validation results show that the RSI can effectively map the distribution of snow cover in these cases, and all of the classification accuracies are above 95%. Signal saturation slightly affects PMS images, but cloud contamination is an important limiting factor. Therefore, we propose that the RSI is an efficient method for monitoring snow cover from GF-4 PMS imagery without requiring the SWIR reflectance. © 2018 by the authors."
"6602988199;7003777747;35547807400;36894599500;24329376600;57203200427;12240390300;57110426700;57189524073;7006462819;12139043600;7102976560;6602414959;57109884900;7004214645;7202079615;22986631300;","Weak hydrological sensitivity to temperature change over land, independent of climate forcing",2018,"10.1038/s41612-017-0005-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047013259&doi=10.1038%2fs41612-017-0005-5&partnerID=40&md5=4e1d8d1e5091755ba1a4a480d772016c","We present the global and regional hydrological sensitivity (HS) to surface temperature changes, for perturbations to CO2, CH4, sulfate and black carbon concentrations, and solar irradiance. Based on results from ten climate models, we show how modeled global mean precipitation increases by 2–3% per kelvin of global mean surface warming, independent of driver, when the effects of rapid adjustments are removed. Previously reported differences in response between drivers are therefore mainly ascribable to rapid atmospheric adjustment processes. All models show a sharp contrast in behavior over land and over ocean, with a strong surface temperature-driven (slow) ocean HS of 3–5%/K, while the slow land HS is only 0–2%/K. Separating the response into convective and large-scale cloud processes, we find larger inter-model differences, in particular over land regions. Large-scale precipitation changes are most relevant at high latitudes, while the equatorial HS is dominated by convective precipitation changes. Black carbon stands out as the driver with the largest inter-model slow HS variability, and also the strongest contrast between a weak land and strong sea response. We identify a particular need for model investigations and observational constraints on convective precipitation in the Arctic, and large-scale precipitation around the Equator. © 2018, The Author(s)."
"56892889800;54397987500;15830929400;7501757094;","Intraseasonal responses of the East Asia summer rainfall to anthropogenic aerosol climate forcing",2018,"10.1007/s00382-017-3691-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018818609&doi=10.1007%2fs00382-017-3691-0&partnerID=40&md5=5e16cdf9b700f4934a50e5a88e7e2a05","The WRF Model is used to investigate intraseasonal responses of the summer rainfall to aerosol direct and cloud-adjustment effects over East Asia, where the anthropogenic aerosol loading has been increasing in the past few decades. The responses are evaluated by comparing two cases for each year during 2002–2008: a control case imposing the observed aerosol optical depth of the corresponding year and a sensitivity case having anthropogenic components of the control case reduced by 75%. Analyses of multiple-year simulations reveal that aerosol-induced changes of rainfall and circulation exhibit strong intraseasonal variability, and that the spatial pattern of changes in the monthly rainfall is related to the intensification and westward extension of the western North-Pacific subtropical high (WNPSH) by increased aerosols. This perturbation of the WNPSH induces surface air divergence over the southeast China and convergence over regions to the north and west of the WNPSH, causing, respectively, decreased and increased rainfall. As the WNPSH migration path varies year by year, however, the variability of rainfall changes over subregions of the eastern China (e.g., North China) is large within the decade. Meanwhile, the pattern of summer-gross rainfall changes also shows large interannual variation, but the general pattern of wetter in the west and dryer in the east persists. Results also suggest that the aerosol increase tends to reduce the number of Tibet Plateau vortices, which indirectly influence summer rainfall over the eastern China. © 2017, Springer-Verlag Berlin Heidelberg."
"57188757971;35546736600;6603260465;36608072400;","Quantifying the early snowmelt event of 2015 in the Cascade Mountains, USA by developing and validating MODIS-based snowmelt timing maps",2018,"10.1007/s11707-018-0719-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052053344&doi=10.1007%2fs11707-018-0719-7&partnerID=40&md5=e1e526ccf0babf5f553ab51057ea4c9d","Spring snowmelt serves as the major hydrological contribution to many watersheds of the US West. Since the 1970s the conterminous western USA has seen an earlier arrival of spring snowmelt. The extremely low snowpack and early melt of 2015 in the Cascade Mountains may be a harbinger of winters to come, underscoring the interest in advancements in spring snowmelt monitoring. Target-of-opportunity and point measurements of snowmelt using meteorological stations or stream gauges are common sources of these data, however, there have been few attempts to identify snowmelt timing using remote sensing. In this study, we describe the creation of snowmelt timing maps (STMs) which identify the day of year that each pixel of a remotely sensed image transitions from “snow-covered” to “no snow” during the spring melt season, controlling for cloud coverage and ephemeral spring snow storms. Derived from the 500 m MODerate-resolution Imaging Spectroradiometer (MODIS) standard snow map, MOD10A2, this new dataset provides annual maps of snowmelt timing, with corresponding maps of cloud interference and interannual variability in snow coverage from 2001–2015. We first show that the STMs agree strongly with in-situ snow telemetry (SNOTEL) meteorological station measurements in terms of snowmelt timing. We then use the STMs to investigate the early snowmelt event of 2015 in the Cascade Mountains, USA, highlighting the protected areas of Mt. Rainier, Crater Lake, and Lassen Volcanic National Parks. In 2015 the Cascade Mountains experienced snowmelt 41 days earlier than the 2001–2015 average, with 25% of its land area melting>65 days earlier than average. The upper elevations of the Cascade Mountains experienced the greatest snowmelt anomaly. Our results are relevant to land managers and biologists as they plan adaptation strategies for mitigating the effects of climate change throughout temperate mountains. © 2018, Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature."
"7102193013;","Is the global atmospheric model MRI-AGCM3.2 better than the CMIP5 atmospheric models in simulating precipitation over East Asia?",2018,"10.1007/s00382-016-3335-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988422985&doi=10.1007%2fs00382-016-3335-9&partnerID=40&md5=a929e45d1809166cb1c907328045342d","The reproducibility of precipitation over East Asia (110–150°E, 20–50°N) by the Meteorological Research Institute-Atmospheric General Circulation Model version 3.2 (MRI-AGCM3.2) was investigated and compared with those by global atmospheric models participated in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The 20, 60 and 180-km grid size version of this model were used to evaluate the dependence of model performance on horizontal resolution. The dependence of cumulus convection scheme on model performance was also investigated. All the MRI-AGCM3.2 models and the CMIP5 models were forced with observed historical sea surface temperatures for the period 1979–2003 (25 years). The reproducibility of the MRI-AGCM3.2 models is higher or comparable to that of the CMIP5 models for seasonal average precipitation, the seasonal March of rainy zone and extreme precipitation events. Especially in summer, the advantage of the MRI-AGCM3.2 models over the CMIP5 models is striking in terms of various skill measures. This is partly due to the higher horizontal resolution of the MRI-AGCM3.2 models, but the performance of models is also sensitive to and depends on cumulus convection scheme. The better simulation of summer precipitation over East Asia by the MRI-AGCM3.2 models can be partly attributed to the better simulation of precipitation, the West Pacific Subtropical High and the local Hadley circulation in the tropics. This study highlights that higher reproducibility of summertime precipitation over East Asia requires proper simulation not only for tropical circulation but also for the strong dynamical linkage between precipitation over East Asia and tropical circulation. © 2016, Springer-Verlag Berlin Heidelberg."
"9333293800;37065366000;57195456927;55361124400;16315420300;","Landsat time series analysis of fractional plant cover changes on abandoned energy development sites",2018,"10.1016/j.jag.2018.07.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061055879&doi=10.1016%2fj.jag.2018.07.008&partnerID=40&md5=5c543a7e313280db667ef72ac88a49d7","Oil and natural gas development in the western United States has increased substantially in recent decades as technological advances like horizontal drilling and hydraulic fracturing have made extraction more commercially viable. Oil and gas pads are often developed for production, and then capped, reclaimed, and left to recover when no longer productive. Understanding the rates, controls, and degree of recovery of these reclaimed well sites to a state similar to pre-development conditions is critical for energy development and land management decision processes. Here we use a multi-decadal time series of satellite imagery (Landsat 5, 1984–2011) to assess vegetation regrowth on 365 abandoned well pads located across the Colorado Plateau in Utah, Colorado, and New Mexico. We developed high-frequency time series of the Soil-Adjusted Total Vegetation Index (SATVI) for each well pad using the Google Earth Engine cloud computing platform. BFAST time-series models were used to fit temporal trends, identifying when vegetation was cleared from the site and the magnitudes and rates of vegetation change after abandonment. The time series metrics are used to calculate the relative fractional vegetation cover (RFVC) of each pad, a measure of post-abandonment vegetation cover relative to pre-drilling condition. Mean and median RFVC were 36% (s.d. 33%) and 26%, respectively, five years after abandonment, with one third of well pads having RFVC greater than 50%. Statistical analyses suggest that much of the high vegetation cover is associated with weedy invasive annual species such as cheatgrass (Bromus tectorum) and Russian thistle (Salsola spp.). Climate conditions and the year of abandonment also play a role, with increased cover in later years associated with a wetter period. Non-linear change at many pads suggests longer recovery times than would be estimated by linear extrapolation. New techniques implemented here address a complex response of cover change to soils, management, and climate over time, and can be extended to the operational monitoring of energy development across large areas. © 2018"
"7402019850;7404297096;57199000346;24491752100;","MISR-GOES 3D winds: Implications for future LEO-GEO and LEO-LEO winds",2018,"10.3390/rs10121885","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058878989&doi=10.3390%2frs10121885&partnerID=40&md5=0110b80e37dab03253a71f63e534380d","Global wind observations are fundamental for studying weather and climate dynamics and for operational forecasting. Most wind measurements come from atmospheric motion vectors (AMVs) by tracking the displacement of cloud or water vapor features. These AMVs generally rely on thermal infrared (IR) techniques for their height assignments, which are subject to large uncertainties in the presence of weak or reversed vertical temperature gradients near the planetary boundary layer (PBL) and tropopause folds. Stereo imaging can overcome the height assignment problem using geometric parallax for feature height determination. In this study we develop a stereo 3D-Wind algorithm to simultaneously retrieve AMV and height from geostationary (GEO) and low Earth orbit (LEO) satellite imagery and apply it to collocated Geostationary Operational Environmental Satellite (GOES) and Multi-angle Imaging SpectroRadiometer (MISR) imagery. The new algorithm improves AMV and height relative to products from GOES or MISR alone, with an estimated accuracy of < 0.5 m/s in AMV and < 200 m in height with 2.2 km sampling. The algorithm can be generalized to other LEO-GEO or LEO-LEO combinations for greater spatiotemporal coverage. The technique demonstrated with MISR and GOES has important implications for future high-quality AMV observations, for which a low-cost constellation of CubeSats can play a vital role. © 2018 by the authors."
"6701879015;57194760335;57195333815;","Phylogeography of a west-Beringian endemic plant: An ancient seed of Stellaria jacutica Schischk. detected in permafrost deposits of the last interglacial",2018,"10.1016/j.revpalbo.2018.09.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054408656&doi=10.1016%2fj.revpalbo.2018.09.012&partnerID=40&md5=c79b60dc85de241d12e8b85ca4e09dc8","Beringia, the landmass connecting Eurasia and North America during Pleistocene sea level low stands, played a crucial part in the phylogeographic history of northern plants, animals and humans. Beringia was not only route for migration between both continents but, as the only unglaciated sector of the Arctic, it was also an important refugial area for northern biota during the Pleistocene. The finding of a fossil seed of Stellaria jacutica Schischk., endemic in Yakutia and the Russian Far Eastern Magadan Oblast, in permafrost deposits near Batagay demonstrates the existence of that species in the Yakutian Yana Highlands already during the last Pleistocene interglacial, about 125 ka ago. The biogeographical, ecological and seed morphological characters of S. jacutica allow for conclusions on its phylogenetic relationships. Stellaria jacutica is the only large seeded Stellaria species occurring in northeast Siberia today. According to carpological characters, S. jacutica is closely related to south Siberian large-seeded Stellaria species, which have a centre of diversity in the Altai-Sayan mountain range. This kinship is also suggested by corresponding ecological preferences and occurrence in mountain steppes and rock steppe communities mainly in the alpine belt of mountains. The spread of S. jacutica's ancestor north-eastwards assumedly happened during a Pleistocene cold stage, when the climate in Siberia was cooler, drier and more continental than during warm stages. Spread and following allopatric speciation hence occurred prior to the last interglacial, i.e. during or prior to the middle Pleistocene. © 2018 Elsevier B.V."
"55636321858;11239766800;","Point cloud technology and 2D computational flow dynamic modeling for rapid hazards and disaster risk appraisal on Yellow Creek fan, Southern Alps of New Zealand",2018,"10.1186/s40645-018-0208-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053217052&doi=10.1186%2fs40645-018-0208-3&partnerID=40&md5=294ae71e129b2a86c66095980cd9cb40","Glacial recession in Alpine Valleys uncorks low-altitude tributary valleys that spill trapped sediments in the sediment cascade, in turn generating sediment-related hazards and flood hazards. Within this complex, the present contribution investigates the transition zone between the tributary and the main valley at Fox Glacier, New Zealand, where glacier recession has allowed the development of large debris flow fans. As the valley is narrow and its geomorphology is rapidly evolving, 3D point cloud technologies based on aerial photogrammetry from UAV or ground and airborne laser technologies are essential to understand the geomorphology and generate boundary conditions to run hazard simulations such as debris flows. Using airborne structure from motion photogrammetry with ground control points collected by RTK-GNSS, we investigated (1) the geomorphology of the valley to understand its evolution and (2) the role of this recent evolution on the flood hazards at the Yellow Creek debris flow fan. The geomorphology of the Fox River valley is a typical U-shape valley with steep valley walls that command the valley by more than 1000 m. The valley walls are connected to the bottom of the valley by active sediment aprons and debris flow fans at the exit of the tributaries. The slopes present several topographic steps or noses on both the aprons and the debris flow fans. By comparison with the glacial recession, they can be related to past locations of the limits of the glacier. On Straight Creek fan, the ridges are perpendicular to the valley and divide the fan between an overgrown half downstream the Fox Valley and an upstream section thinner and smaller. This pattern was also created by the presence of the glacier that stopped the development of the fan on its right (upstream half) while developing the true left hand side of the fan. On the other side of the valley, the debris flow fan of Yellow Creek presents a series of deep trough that control water flows. Flood simulations show that these controls can be overcome and instead of being channeled in other sub-channels, the flow tends to spread on the true right (downstream) end of the fan as a sheet flow. In the 2014 state of the fan, the safest location was thus on the true left half of the fan towards the glacier. Such information is essential as tourists occupy the valley and walk towards the glacier the whole year. [Figure not available: see fulltext.]. © 2018, The Author(s)."
"6603875892;57188727472;","Annual dynamics of shortwave radiation of bare arable lands on a global scale incorporating their roughness",2018,"10.1007/s12665-018-7956-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057262159&doi=10.1007%2fs12665-018-7956-7&partnerID=40&md5=b391b8925b427da57b500e373cd08c0b","Smoothing soil surfaces, which had previously been deeply plowed, increases their albedo, which results in a lower amount of shortwave radiation being absorbed by their surface layer. Those surfaces emit less long-wave radiation too, leading to a reduction in their surface temperature, which can affect the climate. This paper quantitatively estimates the highest possible amount of shortwave radiation that could be reflected throughout the year from bare soils on arable land in the most extensive agricultural regions, where major crops are cultivated, on six of the Earth’s continents. The estimation refers to the highest levels of soil radiation occurring during clear-sky conditions without any clouds when the surfaces that had been conventionally tilled were bare for several days or more after the day of planting and were air-dried in two extreme roughness states: those formed by a plow and a smoothing harrow. The annual dynamics of reflective shortwave radiation of the bare soils were obtained using vectorized and rasterized geostatistical data sets about the areas of the soils and periods when they were bare, as well the spectra of the soil units that occupied the majority of these areas. Adding together all of the diurnal amounts of shortwave radiation reflected from the bare soils for each of the regions in the world, it was found that their radiation peak, appearing on the 140th days of the year, can reach about 22 EJ/day for soils treated by a plow, and a further 3 EJ/day when they are smoothed by a smoothing harrow. © 2018, The Author(s)."
"55803933000;55890961500;8629755300;16680210000;7003298514;7403019018;","A phenology-based approach to the classification of Arctic tundra ecosystems in Greenland",2018,"10.1016/j.isprsjprs.2018.11.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056241600&doi=10.1016%2fj.isprsjprs.2018.11.005&partnerID=40&md5=ac11d653e952e92b57a9a535b7ef7003","The disproportionate warming in the Arctic and the resulting adverse ecosystem changes underline the importance of continued monitoring of these ecosystems. Land-cover classification maps of the Arctic regions are essential for monitoring and change detection purposes, as well as upscaling of various ecosystem processes. However, large-scale land cover maps of the Arctic regions are often too coarse to properly capture the heterogeneity of these landscapes. In this study, we bridge this gap through incorporating multi temporal Landsat-8 OLI data in a large-scale land cover classification, and subsequently produce a tundra classification map for the entire Greenland. An algorithm is developed that allows for the extraction of vegetation phenology from single-year time series of 4169 OLI scenes at 30 m resolution despite the low revisit frequency of the satellite and persistent cloud cover. The phenological metrics, satellite-derived wetness, and terrain information are then used to separate land surface classes using a random forest classifier. The optimal algorithm parameters and input layers are identified, ultimately yielding a cross-validation accuracy of 89.25% across the studied area. Finally, we have conducted a comprehensive analysis on the resulting land-cover map and for the first time presented the geographical distribution, latitudinal gradients, and climate linkages of the various tundra vegetation classes across the ice-free part of Greenland. With a resolution of 30 m and Greenland-wide spatial coverage, the produced land-cover map can support various applications at scales ranging from the landscape to regional level. © 2018 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)"
"55580928400;54397987500;56424145700;57193221172;7102687667;8906055900;","How are heat waves over Yangtze River valley associated with atmospheric quasi-biweekly oscillation?",2018,"10.1007/s00382-017-3526-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011903650&doi=10.1007%2fs00382-017-3526-z&partnerID=40&md5=8c5fab52afef0b61024418f96d297045","Over Yangtze River valley (YRV) where heat wave (HW) events most frequently occur in China during 1979–2014, 30 out of 57 HW events (nearly 55%) in July and August is found to be related with the dry phases of atmospheric quasi-biweekly oscillation (QBWO). When a significant low-level anticyclonic anomaly (LAA) associated with QBWO appears over YRV, temperature rises sharply according to the adiabatic heating caused by subsidence and the enhanced downward solar radiation due to decreased clouds. The LAA with subsidence over YRV is primarily generated by quasi-biweekly atmospheric waves, which are classified to three types through case-by-case categorization, named as “mid-latitude wavetrain”, “WNP (western North Pacific) wavetrain” and “double wavetrains”, respectively. The mid-latitude wavetrain QBWO causes the LAA through subsidence induced by upper-level cyclonic vorticity which is associated with an eastward/southeastward migrating wave train from Eastern Europe to WNP in the upper troposphere. The WNP wavetrain QBWO forms LAA through a northwestward migrating lower-tropospheric wave train emanating from tropical WNP to southeastern China. The double wavetrains QBWO triggers LAA through both the low-level shear anticyclonic vorticity provided by a low-level northwestward/westward propagating wave train from tropical WNP to South China Sea and the upper-level positive vorticity associated with an eastward/southeastward migrating wave train from Eastern Europe to southeastern China in the upper troposphere. In all cases, South Asian High extends eastward and WNP subtropical high extends westward during HW events. Tracing these distinct precursory circulation anomalies may facilitate better understanding and short-medium range forecast of HW. © 2017, Springer-Verlag Berlin Heidelberg."
"56972775300;8987631200;","The role of polygonal eyewalls in rapid intensification of Typhoon Megi (2010)",2018,"10.1175/JAS-D-18-0100.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059289169&doi=10.1175%2fJAS-D-18-0100.1&partnerID=40&md5=01400ba6561cb48ae68c9f01019f342b","High-resolution numerical experiments for Typhoon Megi (2010) in the western North Pacific are conducted using the Advanced Research version of the Weather Research and Forecasting (WRF) Model to understand the mechanisms of rapid intensification (RI). With a dynamically initialized vortex, sensitivity experiments are carried out focusing on the planetary boundary layer (PBL) and the following microphysics schemes: WRF single-moment 6-class (WSM6) and WRF double-moment 6-class (WDM6) microphysics with Yonsei University, Mellor-Yamada-Janjic (MYJ), and Mellor-Yamada-Nakanishi-Niino (MYNN) 2.5-level (MN2.5) and 3.0-level (MN3) PBL schemes. The largest differences are found between WSM6-MN3 and WDM6-MN3, and we therefore examine RI mechanisms based on the results of these experiments. Prior to RI, WDM6-MN3 shows a drier environment and stronger downdrafts in the lower troposphere than in WSM6-MN3. As a result, during the RI period, WSM6-MN3 (WDM6-MN3) significantly intensifies with the minimum sea level pressure decreasing by 51 (29) hPa and the maximum surface wind increasing by 28 (12) m s -1 in 24 h. In both experiments, the maximum values of surface heat fluxes, potential vorticity (PV), radial absolute angular momentum advection, inertial stability, supergradient wind, and convective bursts inside the radius of maximum winds are frequently observed at each vertex of polygonal eyewalls in the lower troposphere. In particular, WSM6-MN3 exhibits more convective cells inside the inner-core region, a more persistent and thicker polygonal eyewall in the lower troposphere, and a more robust vertical structure of hydrometeors and vertical velocity than WDM6-MN3. This study suggests that within the inner-core region, polygonal eyewalls like WSM6-MN3 provide favorable conditions for RI. © 2018 American Meteorological Society."
"57204899238;7401651197;","Instrument artifacts lead to uncertainties in parameterizations of cloud condensation nucleation",2018,"10.5194/amt-11-6389-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057731883&doi=10.5194%2famt-11-6389-2018&partnerID=40&md5=ba8ecdbb6263fcedaa79102dd39275a7","The concentrations of cloud condensation nuclei (CCN) modulate cloud properties, rainfall location and intensity, and climate forcings. This work assesses uncertainties in CCN measurements and the apparent hygroscopicity parameter (κapp), which is widely used to represent CCN populations in climate models. CCN measurements require accurate operation of three instruments: The CCN instrument, the differential mobility analyzer (DMA), and the condensation particle counter (CPC). Assessment of DMA operation showed that varying the ratio of aerosol to sheath flow from 0.05 to 0.30 resulted in discrepancies between the κapp values calculated from CCN measurements and the literature value. Discrepancies were found to increase from < 1% to 13% for both sodium chloride and ammonium sulfate. The ratio of excess to sheath flow was also varied, which shifted the downstream aerosol distribution towards smaller particle diameters (for excess flow Co-condensation of inorganic or organic vapours on growing droplets could significantly enhance both cloud condensation nucleus (CCN) and cloud droplet number concentration, thereby influencing cloud albedo and climate. Until now, there has been very few direct observational evidence of this process. We have measured the growth of inorganic salt particles exposed to both water and organic vapours at 291.15K in the laboratory, showing that co-condensation of the organic vapours significantly enhances water uptake of aerosols. After exposure to water and propylene glycol vapours, ammonium sulfate particles grew much more than any previously measured particles, inorganic or organic, at the same relative humidity (RH). The maximum equivalent hygroscopicity parameter, was observed to reach up to 2.64, very much higher than values (0.1lt;0.9) measured for atmospheric particulate matter using conventional instrumentation, which may be blind to this effect. Under a continuously replenishing organic vapour field, the particles never reached equilibrium owing to the presence of the involatile solute and were observed to continuously grow with increasing exposure time, in agreement with model simulations. Co-condensation of butylene glycol (which has similar volatility but, at aw Combining double low line 0.9, a higher Sorg than propylene glycol in our system) and tri-ethylene glycol (which has lower volatility and, at aw Combining double low line 0.9, lower Sorg than propylene glycol in our system) vapours was additionally measured in this study. The maximum equivalent hygroscopicity parameter, reached as high as 8.48 for ammonium sulfate particles exposed to water and tri-ethylene glycol vapours at 90% RH. This enhancement of particle water uptake through co-condensation of vapours constitutes the direct measurement of this process, which may substantially influence cloud droplet formation in the atmosphere. In addition, the model simulations for exposure to co-condensing butylene glycol and tri-ethylene glycol vapours with water show that there are factors other than Sorg which influence the co-condensation of semi-volatile organic compounds (SVOCs) that are as yet not understood. © Author(s) 2018."
"56893786200;","The Relationship Between Cloud Radiative Effect and Surface Temperature Variability at El Niño-Southern Oscillation Frequencies in CMIP5 Models",2018,"10.1029/2018GL079236","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054170189&doi=10.1029%2f2018GL079236&partnerID=40&md5=27992f88a43b8787a3df76e93bf0639a","The relationship between the tropical cloud radiative effect (CRE) and tropical surface temperature variability on El Niño–Southern Oscillation (ENSO) time scales is investigated in preindustrial control simulations from the fifth Climate Model Intercomparison Project (CMIP5) archive. The tropical CRE is binned according to midtropospheric vertical velocities and then regressed in frequency space versus tropical mean surface temperatures. Low clouds play a leading role in the relationship between clouds and surface temperature variability, amplifying ENSO-induced surface temperature anomalies through thermodynamically driven changes in the shortwave CRE. Changes in CRE driven by changes in the large-scale dynamics have a minor influence on surface temperature variability. It is shown that the regression coefficients at ENSO frequencies between the CRE in regions of moderate subsidence and of weak ascent, and tropical mean surface temperatures are well correlated with models' climate sensitivities, constituting a potential emergent constraint on climate sensitivity. ©2018. American Geophysical Union. All Rights Reserved."
"55355176000;8067118800;","The Impact of Process-Based Warm Rain Constraints on the Aerosol Indirect Effect",2018,"10.1029/2018GL079956","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054665254&doi=10.1029%2f2018GL079956&partnerID=40&md5=4eb4c7b22f46ee0b4411037cf96924c9","Many global climate models have been found to generate warm rain too frequently. This study, with a particular global climate model, found that the problem can be mitigated via altering the autoconversion process so as to inhibit rain formation under conditions of a large cloud number concentration and small droplet sizes. However, this improvement was found to cause an overly large aerosol indirect effect. This dichotomy between the constraint on warm-rain formation process and the energy-budget requirement on aerosol indirect effect was found to result from a pronounced cloud-water response to aerosol perturbations, which is amplified through the wet scavenging feedback to an extent depending on precipitation-formation parameterization. Thus, critical compensating errors exist between warm-rain formation and other key processes, and better constraint on these processes, particularly wet scavenging, is required to mitigate the dichotomy. The results have broad implication for models that suffer from the aforementioned too-frequent warm-rain formation bias. ©2018. The Authors."
"56898396100;23028245500;55574869900;7102423967;57204185658;","Examining Intrinsic Aerosol-Cloud Interactions in South Asia Through Multiple Satellite Observations",2018,"10.1029/2017JD028232","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054869454&doi=10.1029%2f2017JD028232&partnerID=40&md5=43784faa11b2e848e71fc6d2a8d5975f","Changes in anthropogenic aerosol loading affect cloud albedo and the Earth's radiative balance with a low level of scientific understanding. Aerosol-cloud interaction and its effects on climate are mainly evaluated using passive observations in a global scale. Here this study estimated the intrinsic response of clouds to aerosols by combining active and passive satellite observations from July 2006 to February 2011 in South Asia. We evaluate the average radiative forcing by the intrinsic aerosol-cloud interaction for warm liquid clouds as 0.63 ± 0.19, −0.34 ± 0.40, and 1.11 ± 0.08 W/m2 during the annual, monsoon, and nonmonsoon periods in South Asia, respectively. Relationships derived among liquid water path, cloud droplet number concentration, and consequent cloud albedo are assessed as a function of aerosol concentration. The intensity of the aerosol-cloud interaction gradually weakens with increasing cloud base height above ground level in South Asia, is associated with aerosol vertical distribution and vertical atmospheric upward motion. Moreover, distinct regional and seasonal variations in the aerosol-cloud interaction are observed for liquid water path, cloud droplet number concentration, and the resulting cloud albedo in South Asia. These variations are associated with water vapor and aerosol absorption levels. Results contribute to the understanding and modeling of aerosol-cloud interactions and determining their effects on radiative forcing and climate in South Asia. ©2018. American Geophysical Union. All Rights Reserved."
"56940255600;7410041005;","Uncertainties in MODIS-Based Cloud Liquid Water Path Retrievals at High Latitudes Due to Mixed-Phase Clouds and Cloud Top Height Inhomogeneity",2018,"10.1029/2018JD028558","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054584575&doi=10.1029%2f2018JD028558&partnerID=40&md5=35de5e094f0eaeb2777974e98a900a4d","Combined A-train remote sensing measurements from Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E), CloudSat, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to study MODIS liquid water path (LWP) uncertainties at high latitudes. The focus is on quantifying uncertainties due to mixed-phase clouds and solar zenith angle-dependent bias, both of which disproportionately affect the MODIS data set in the polar regions. Multisensor LWP retrievals in stratiform mixed-phase clouds show that treating mixed-phase clouds as liquid clouds result in LWP bias that is related to the ice water path (IWP) on average and reaches close to 15% at IWP of 150 g/m2 and can reach 40% or higher when IWP is greater than 400 g/m2. Moreover, A-train measurements and radiative transfer modeling are used to further understand the well-known yet unresolved solar zenith angle-dependent high bias in MODIS LWP. It is shown that the cloud top height variation is one of the main factors that contribute to this bias due to three-dimensional radiative interactions with cloud top inhomogeneity. Excluding only 0.5% of data points that show significant three-dimensional errors reduces the bias by 25 g/m2 at solar zenith angle of 80° and improves agreement with the AMSR-E LWP trends. Three-dimensional radiative transfer simulations confirm that cloud top inhomogeneity is primarily responsible for the solar zenith angle-dependent LWP bias as observed by the MODIS measurements. This study provides a framework to guide future improvements of MODIS LWP data set, which is a key data source to constrain climate models. ©2018. American Geophysical Union. All Rights Reserved."
"13405561000;8918407000;35104877900;36655323000;","Changes in Marine Fog Over the North Pacific Under Different Climates in CMIP5 Multimodel Simulations",2018,"10.1029/2018JD028899","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054588037&doi=10.1029%2f2018JD028899&partnerID=40&md5=130308301e50560ff9f997e38f94e067","In this study, the changes in the occurrence of marine fog over the summer North Pacific in warmer sea surface temperature (SST) or increased CO2 climates were investigated based on atmospheric model simulations by using the fifth phase of the Climate Model Intercomparison Project (CMIP5) multimodel data. Initially, the marine fog representation in CMIP5 multimodels was briefly evaluated globally. We found that the simulated marine fog occurrence was represented relatively well in boreal summer but poorly in other seasons. The results indicated that the changes in the North Pacific high-pressure system accompanied by changes in horizontal wind patterns control the changes in marine fog occurrence in the North Pacific. The magnitude of contrasting pair changes in marine fog occurrence in the western and eastern North Pacific are primarily determined by the magnitude of changes in the North Pacific high-pressure system. Global-scale changes in the vertical profiles of the atmosphere (stability changes) can also affect the marine fog changes. These changes in marine fog over the North Pacific were consistent among most CMIP5 models. ©2018. American Geophysical Union. All Rights Reserved."
"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."
"57196326132;57203275224;","Evidence for Radiative-Convective Bistability in Tropical Atmospheres",2018,"10.1029/2018GL078903","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054411567&doi=10.1029%2f2018GL078903&partnerID=40&md5=9c661254accbf9540d9bf60b9104e488","Earth's energy balance requires that energy absorbed and emitted at the top of the atmosphere be equal; to first order this balance is maintained via the Planck feedback: outgoing longwave radiation increases as surface temperature increases. Failure of the Planck feedback to stabilize the climate is described by three generally independent phenomena: the super-greenhouse effect, the runaway greenhouse, and multiple equilibria of radiative-convective atmospheres. Here we use satellite observations and models to show that the existence of the super-greenhouse gives rise to a radiative-convective instability which is relevant to Earth's tropics. The super-greenhouse is caused by the low troposphere becoming optically thick, causing a positive feedback on near surface temperature and moisture, driving deep convection, column moistening, and reduced outgoing longwave radiation. Aspects of the runaway greenhouse physics are implicated, but a local runaway greenhouse is avoided. These results have implications for understanding the response of the tropics to a warming world. ©2018. The Authors."
"57193652896;57173163200;57203382356;7004379793;8839237600;","Tropical Montane Cloud Forests in the Orinoco River basin: Inferring fog interception from through-fall dynamics",2018,"10.1016/j.agrformet.2018.05.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047909228&doi=10.1016%2fj.agrformet.2018.05.016&partnerID=40&md5=44483439384c558a1d9ee815c32f0ca5","The interaction between vegetation and the atmosphere is highly complex in fog affected ecosystems like Tropical Montane Cloud Forests (TMCFs). Despite acknowledging fog effects on the canopy's water balance, quantifying their influence remains challenging. While the reduction in potential evaporation that is caused by fog presence, is largely independent of land cover, fog interception itself strongly depends on the land-cover's vegetation characteristics. A better understanding of how these two fog related processes affect the water balance is highly relevant under current land-use and climate-change pressures. In this study we evaluate the different fog effects on TMCFs’ canopy interception combining model simulations and high temporal resolution (10 min) observations that were collected in different TMCF regeneration stages: early succession, secondary and old-growth TMCFs. We also analyse the difficulties in closing catchment water balances caused by limitations on the interpretation of throughfall data to properly represent these fog effects. Results show that different fog frequencies along elevation affect potential evaporation. The higher elevation old-growth TMCFs have a lower simulated evaporation and a lower dry canopy frequency than the low elevation secondary and early succession forests. Furthermore, we show that fog water inputs during fog-only events, even though higher at the higher elevation, are irrelevant as water inputs (from 0.8% to 1.6% of measured rainfall), but fog's contribution to through-fall during foggy rainfall events can be more relevant (from 5.8%–12.8% of measured rainfall). Additional to the fog trends along the elevation, we also uncover variable fog-vegetation interactions controlled by differences in canopy water storages as a function of forest cover. Each evaluated process has associated uncertainties, which together cumulatively explain why closing a water budget in TMCF catchments is limited by data collection methods that probably do not capture all relevant fog effects. In addition, this study also indicates that the temporal resolution of measured rainfall and through-fall and compensating effects of canopy parameters that are estimated by the commonly used Rutter canopy-rainfall interception model, pose an additional challenge to understand and quantify fog effects in the water budgets of TMCFs. © 2018 Elsevier B.V."
"57217266035;57204216001;35232912700;57201215838;57204209556;57213358341;57140859500;35405390200;28568055900;24722339600;","Time-dependent entrainment of smoke presents an observational challenge for assessing aerosol-cloud interactions over the southeast Atlantic Ocean",2018,"10.5194/acp-18-14623-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054958865&doi=10.5194%2facp-18-14623-2018&partnerID=40&md5=e70dcd518bcd5ef123dacac5c4bffec0","The colocation of clouds and smoke over the southeast Atlantic Ocean during the southern African biomass burning season has numerous radiative implications, including microphysical modulation of the clouds if smoke is entrained into the marine boundary layer. NASA's ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign is studying this system with aircraft in three field deployments between 2016 and 2018. Results from ORACLES-2016 show that the relationship between cloud droplet number concentration and smoke below cloud is consistent with previously reported values, whereas cloud droplet number concentration is only weakly associated with smoke immediately above cloud at the time of observation. By combining field observations, regional chemistry-climate modeling, and theoretical boundary layer aerosol budget equations, we show that the history of smoke entrainment (which has a characteristic mixing timescale on the order of days) helps explain variations in cloud properties for similar instantaneous above-cloud smoke environments. Precipitation processes can obscure the relationship between above-cloud smoke and cloud properties in parts of the southeast Atlantic, but marine boundary layer carbon monoxide concentrations for two case study flights suggest that smoke entrainment history drove the observed differences in cloud properties for those days. A Lagrangian framework following the clouds and accounting for the history of smoke entrainment and precipitation is likely necessary for quantitatively studying this system; an Eulerian framework (e.g., instantaneous correlation of A-train satellite observations) is unlikely to capture the true extent of smoke-cloud interaction in the southeast Atlantic. © 2018 Author(s)."
"56300206800;57192962897;57192298390;56888287100;55486117400;56411079900;57145546300;8075033200;56520903100;35265615300;36836439900;55718911800;","Cloud scavenging of anthropogenic refractory particles at a mountain site in North China",2018,"10.5194/acp-18-14681-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054993443&doi=10.5194%2facp-18-14681-2018&partnerID=40&md5=7bb03b47925840a0e70c0dd6908792d2","Aerosol-cloud interactions remain a major source of uncertainty in climate forcing estimates. Few studies have been conducted to characterize the aerosol-cloud interactions in heavily polluted conditions worldwide. In this study, cloud residual and cloud interstitial particles were collected during cloud events under different pollution levels from 22 July to 1 August 2014 at Mt. Tai (1532 m above sea level) located in the North China Plain (NCP). A transmission electron microscope was used to investigate the morphology, size, and chemical composition of individual cloud residual and cloud interstitial particles, and to study mixing properties of different aerosol components in individual particles. Our results show that S-rich particles were predominant (78 %) during clean periods (PM2.5< 15 μ3), but a large number of anthropogenic refractory particles (e.g., soot, fly ash, and metal) and their mixtures with S-rich particles (defined as ""S-refractory"") were observed during polluted periods. Cloud droplets collected during polluted periods were found to become an extremely complicated mixture by scavenging abundant refractory particles. We found that 76 % of cloud residual particles were S-refractory particles and that 26 % of cloud residual particles contained two or more types of refractory particles. Soot-containing particles (i.e., S-soot and S-fly ash/metal-soot) were the most abundant (62 %) among cloud residual particles, followed by fly ash/metal-containing particles (i.e., S-fly ash/metal and Sfly ash/metal-soot, 37 %). These complicated cloud droplets have not been reported in clean continental or marine air before. Our findings provide an insight into the potential impacts on cloud radiative forcing from black carbon and metal catalyzed reactions of SO2 in micro-cloud droplets containing soluble metals released from fly ash and metals over polluted air. © 2018 Author(s)."
"55326237100;55173596300;7402838215;55366700000;23017945100;6506848120;57204179735;6602600408;","Ice crystal number concentration estimates from lidar-radar satellite remote sensing - Part 1: Method and evaluation",2018,"10.5194/acp-18-14327-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054864630&doi=10.5194%2facp-18-14327-2018&partnerID=40&md5=611c529bd9e2f9e33b4b06357c288035","The number concentration of cloud particles is a key quantity for understanding aerosol-cloud interactions and describing clouds in climate and numerical weather prediction models. In contrast with recent advances for liquid clouds, few observational constraints exist regarding the ice crystal number concentration (N). This study investigates how combined lidar-radar measurements can be used to provide satellite estimates of N, using a methodology that constrains moments of a parameterized particle size distribution (PSD). The operational liDAR-raDAR (DARDAR) product serves as an existing base for this method, which focuses on ice clouds with temperatures 30 °C. Theoretical considerations demonstrate the capability for accurate retrievals of N, apart from a possible bias in the concentration in small crystals when 50 °C, due to the assumption of a monomodal PSD shape in the current method. This is verified via a comparison of satellite estimates to coincident in situ measurements, which additionally demonstrates the sufficient sensitivity of lidar-radar observations to N. Following these results, satellite estimates of N are evaluated in the context of a case study and a preliminary climatological analysis based on 10 years of global data. Despite a lack of other large-scale references, this evaluation shows a reasonable physical consistency in N spatial distribution patterns. Notably, increases in N are found towards cold temperatures and, more significantly, in the presence of strong updrafts, such as those related to convective or orographic uplifts. Further evaluation and improvement of this method are necessary, although these results already constitute a first encouraging step towards large-scale observational constraints for N. Part 2 of this series uses this new dataset to examine the controls on. © 2018 Copernicus GmbH. All Rights Reserved."
"57190177918;56591585100;21742333400;22933265100;7402838215;6701378450;55976582900;21744073500;7005219614;15019752400;","Implementation of a comprehensive ice crystal formation parameterization for cirrus and mixed-phase clouds in the EMAC model (based on MESSy 2.53)",2018,"10.5194/gmd-11-4021-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052116192&doi=10.5194%2fgmd-11-4021-2018&partnerID=40&md5=1617c3da767cc248940f77f787156344","A comprehensive ice nucleation parameterization has been implemented in the global chemistry-climate model EMAC to improve the representation of ice crystal number concentrations (ICNCs). The parameterization of Barahona and Nenes (2009, hereafter BN09) allows for the treatment of ice nucleation taking into account the competition for water vapour between homogeneous and heterogeneous nucleation in cirrus clouds. Furthermore, the influence of chemically heterogeneous, polydisperse aerosols is considered by applying one of the multiple ice nucleating particle parameterizations which are included in BN09 to compute the heterogeneously formed ice crystals. BN09 has been modified in order to consider the pre-existing ice crystal effect and implemented to operate both in the cirrus and in the mixed-phase regimes. Compared to the standard EMAC parameterizations, BN09 produces fewer ice crystals in the upper troposphere but higher ICNCs in the middle troposphere, especially in the Northern Hemisphere where ice nucleating mineral dust particles are relatively abundant. Overall, ICNCs agree well with the observations, especially in cold cirrus clouds (at temperatures below 205 K), although they are underestimated between 200 and 220 K. As BN09 takes into account processes which were previously neglected by the standard version of the model, it is recommended for future EMAC simulations. © Author(s) 2018."
"6602450405;6506286986;7004248952;","Cloud liquid water path in the sub-Arctic region of Europe as derived from ground-based and space-borne remote observations",2018,"10.5194/amt-11-5439-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054521772&doi=10.5194%2famt-11-5439-2018&partnerID=40&md5=373af99f5eab7df5025e17380cf9336d","Tropospheric clouds are a very important component of the climate system and the hydrological cycle in the Arctic and sub-Arctic. Liquid water path (LWP) is one of the key parameters of clouds urgently needed for a variety of studies, including the snow cover and climate modelling at northern latitudes. A joint analysis was made of the LWP values obtained from observations by the SEVIRI satellite instrument and from ground-based observations by the RPG-HATPRO microwave radiometer near St Petersburg, Russia (60° N, 30° E). The time period of selected data sets spans 2 years (December 2012-November 2014) excluding winter months, since the specific requirements for SEVIRI observations restrict measurements at northern latitudes in winter when the solar zenith angle is too large. The radiometer measurement site is located very close to the shore of the Gulf of Finland, and our study has revealed considerable differences between the LWP values obtained by SEVIRI over land and over water areas in the region under investigation. Therefore, special attention was paid to the analysis of the LWP spatial distributions derived from SEVIRI observations at scales from 15 to 150 km in the vicinity of St Petersburg. Good agreement between the daily median LWP values obtained from the SEVIRI and the RPG-HATPRO observations was shown: the rms difference was estimated at 0.016 kg mg-2 for a warm season and 0.048 kg mg-2 for a cold season. Over 7 months (February-May and August-October), the SEVIRI and the RPG-HATPRO instruments revealed similar diurnal variations in LWP, while considerable discrepancies between the diurnal variations obtained by the two instruments were detected in June and July. On the basis of reanalysis data, it was shown that the LWP diurnal cycles are characterised by considerable interannual variability. © Author(s) 2018."
"55928112000;56540693200;55928817500;24398562000;57213447954;6603711967;","Atmospheric processing of iron in mineral and combustion aerosols: Development of an intermediate-complexity mechanism suitable for Earth system models",2018,"10.5194/acp-18-14175-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054519295&doi=10.5194%2facp-18-14175-2018&partnerID=40&md5=a46d9159ba11949955dd6855badeaf69","Atmospheric processing of iron in dust and combustion aerosols is simulated using an intermediate-complexity soluble iron mechanism designed for Earth system models. The solubilization mechanism includes both a dependence on aerosol water pH and in-cloud oxalic acid. The simulations of size-resolved total, soluble and fractional iron solubility indicate that this mechanism captures many but not all of the features seen from cruise observations of labile iron. The primary objective was to determine the extent to which our solubility scheme could adequately match observations of fractional iron solubility. We define a semi-quantitative metric as the model mean at points with observations divided by the observational mean (MMO). The model is in reasonable agreement with observations of fractional iron solubility with an MMO of 0.86. Several sensitivity studies are performed to ascertain the degree of complexity needed to match observations; including the oxalic acid enhancement is necessary, while different parameterizations for calculating model oxalate concentrations are less important. The percent change in soluble iron deposition between the reference case (REF) and the simulation with acidic processing alone is 63.8%, which is consistent with previous studies. Upon deposition to global oceans, global mean combustion iron solubility to total fractional iron solubility is 8.2%; however, the contribution of fractional iron solubility from combustion sources to ocean basins below 15°S is approximately 50%. We conclude that, in many remote ocean regions, sources of iron from combustion and dust aerosols are equally important. Our estimates of changes in deposition of soluble iron to the ocean since preindustrial climate conditions suggest roughly a doubling due to a combination of higher dust and combustion iron emissions along with more efficient atmospheric processing. © 2018 Author(s)."
"7201472576;9246517900;","Inter-comparison and evaluation of the four longest satellite-derived cloud climate data records: CLARA-A2, ESA Cloud CCI V3, ISCCP-HGM, and PATMOS-x",2018,"10.3390/rs10101567","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055434818&doi=10.3390%2frs10101567&partnerID=40&md5=14e9f26b72a0c965d87dd03a85ed2e3f","Results from four global cloud climate data records (ISCCP-HGM, ESA Cloud CCI V3, CLARA-A2 and PATMOS-x) have been inter-compared in global time series plots, in global maps and in zonal region plots covering the period in common, 1984-2009. The investigated cloud parameters were total cloud fraction and cloud top pressure. Averaged seasonal cycles of cloud cover, as observed by the CALIPSO-CALIOP sensor over the 2007-2015 period, were also used as an additional independent and high-quality reference for the study of global cloud cover. All CDRs show good agreement on global cloud amounts (~65%) and also a weak negative trend (0.5-1.9% per decade) over the period of investigation. Deviations between the CDRs are seen especially over the southern mid-latitude region and over the poles. Particularly good results are shown by PATMOS-x and by ESA Cloud CCI V3 when compared to the CALIPSO-CALIOP reference. Results for cloud top pressure show large differences (~60 hPa) between ISCCP-HGM and the other CDRs for the global mean. The two CDR groups show also opposite signs in the trend over the period. © 2018 by the authors."
"55686667100;36701462300;10241250100;55746365900;8067118800;","Low clouds link equilibrium climate sensitivity to hydrological sensitivity",2018,"10.1038/s41558-018-0272-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053659830&doi=10.1038%2fs41558-018-0272-0&partnerID=40&md5=3284d96ee0bbf7b63d50af389d983f5a","Equilibrium climate sensitivity (ECS) and hydrological sensitivity describe the global mean surface temperature and precipitation responses to a doubling of atmospheric CO2. Despite their connection via the Earth’s energy budget, the physical linkage between these two metrics remains controversial. Here, using a global climate model with a perturbed mean hydrological cycle, we show that ECS and hydrological sensitivity per unit warming are anti-correlated owing to the low-cloud response to surface warming. When the amount of low clouds decreases, ECS is enhanced through reductions in the reflection of shortwave radiation. In contrast, hydrological sensitivity is suppressed through weakening of atmospheric longwave cooling, necessitating weakened condensational heating by precipitation. These compensating cloud effects are also robustly found in a multi-model ensemble, and further constrained using satellite observations. Our estimates, combined with an existing constraint to clear-sky shortwave absorption, suggest that hydrological sensitivity could be lower by 30% than raw estimates from global climate models. © 2018, The Author(s), under exclusive licence to Springer Nature Limited."
"7401936984;8859530100;7006705919;15755995900;7102696626;7005920812;55802246600;6506848305;36856321600;9434771700;6701752471;25637373000;55544607500;25629055800;55688930000;55317177900;56384704800;52464731300;","Understanding Cloud and Convective Characteristics in Version 1 of the E3SM Atmosphere Model",2018,"10.1029/2018MS001350","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055745844&doi=10.1029%2f2018MS001350&partnerID=40&md5=79ed364f267768e34ee3f09164eedab1","This study provides comprehensive insight into the notable differences in clouds and precipitation simulated by the Energy Exascale Earth System Model Atmosphere Model version 0 and version 1 (EAMv1). Several sensitivity experiments are conducted to isolate the impact of changes in model physics, resolution, and parameter choices on these differences. The overall improvement in EAMv1 clouds and precipitation is primarily attributed to the introduction of a simplified third-order turbulence parameterization Cloud Layers Unified By Binormals (along with the companion changes) for a unified treatment of boundary layer turbulence, shallow convection, and cloud macrophysics, though it also leads to a reduction in subtropical coastal stratocumulus clouds. This lack of stratocumulus clouds is considerably improved by increasing vertical resolution from 30 to 72 layers, but the gain is unfortunately subsequently offset by other retuning to reach the top-of-atmosphere energy balance. Increasing vertical resolution also results in a considerable underestimation of high clouds over the tropical warm pool, primarily due to the selection for numerical stability of a higher air parcel launch level in the deep convection scheme. Increasing horizontal resolution from 1° to 0.25° without retuning leads to considerable degradation in cloud and precipitation fields, with much weaker tropical and subtropical short- and longwave cloud radiative forcing and much stronger precipitation in the intertropical convergence zone, indicating poor scale awareness of the cloud parameterizations. To avoid this degradation, significantly different parameter settings for the low-resolution (1°) and high-resolution (0.25°) were required to achieve optimal performance in EAMv1. ©2018. The Authors."
"57204068836;7003842561;56143929800;55940397300;45061126700;","Polar cooling effect due to increase of phytoplankton and dimethyl-sulfide emission",2018,"10.3390/atmos9100384","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054381902&doi=10.3390%2fatmos9100384&partnerID=40&md5=5d1abda370df52089a5495a0dd02a912","The effects of increased dimethyl-sulfide (DMS) emissions due to increased marine phytoplankton activity are examined using an atmosphere-ocean coupled climate model. As the DMS emission flux from the ocean increases globally, large-scale cooling occurs due to the DMS-cloud condensation nuclei (CCN)-cloud albedo interactions. This cooling increases as DMS emissions are further increased, with the most pronounced effect occurring over the Arctic, which is likely associated with a change in sea-ice fraction as sea ice mediates the air-sea exchange of the radiation, moisture and heat flux. These results differ from recent studies that only considered the bio-physical feedback that led to amplified Arctic warming under greenhouse warming conditions. Therefore, climate negative feedback from DMS-CCN-cloud albedo interactions that involve marine phytoplankton and its impact on polar climate should be properly reflected in future climate models to better estimate climate change, especially over the polar regions. © 2018 by the authors."
"26645289600;16202694600;7402064802;57203813717;57203817773;35069282600;","Drivers of the low-cloud response to poleward jet shifts in the North Pacific in observations and models",2018,"10.1175/JCLI-D-18-0114.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053031732&doi=10.1175%2fJCLI-D-18-0114.1&partnerID=40&md5=d578c3caf22c477738a45042a9152669","The long-standing expectation that poleward shifts of the midlatitude jet under global warming will lead to poleward shifts of clouds and a positive radiative feedback on the climate system has been shown to be misguided by several recent studies. On interannual time scales, free-tropospheric clouds are observed to shift along with the jet, but low clouds increase across a broad expanse of the North Pacific Ocean basin, resulting in negligible changes in total cloud fraction and top-of-atmosphere radiation. Here it is shown that this low-cloud response is consistent across eight independent satellite-derived cloud products. Using multiple linear regression, it is demonstrated that the spatial pattern and magnitude of the low-cloud-coverage response is primarily driven by anomalous surface temperature advection. In the eastern North Pacific, anomalous cold advection by anomalous northerly surface winds enhances sensible and latent heat fluxes from the ocean into the boundary layer, resulting in large increases in low-cloud coverage. Local increases in low-level stability make a smaller contribution to this low-cloud increase. Despite closely capturing the observed response of large-scale meteorology to jet shifts, global climate models largely fail to capture the observed response of clouds and radiation to interannual jet shifts because they systematically underestimate how sensitive low clouds are to surface temperature advection, and to a lesser extent, low-level stability. More realistic model simulations of cloud-radiation-jet interactions require that parameterizations more accurately capture the sensitivity of low clouds to surface temperature advection. © 2018 American Meteorological Society."
"6603675204;","Electrostatic levitation of volcanic ash into the ionosphere and its abrupt effect on climate",2018,"10.1130/G45092.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054128837&doi=10.1130%2fG45092.1&partnerID=40&md5=1bc74553ad5d9291737e2654cba60df8","Large volcanic eruptions cause short-term climate change owing to the convective rise of fine ash and aerosols into the stratosphere. Volcanic plumes are, however, also associated with large net electrical charges that can also influence the dynamics of their ash particles. Here I show that electrostatic levitation of ash from plumes with a net charge is capable of injecting volcanic particles < 500 nm in diameter into the ionosphere in large eruptions lasting more than a few hours. Measured disturbances in the ionosphere during eruptions, and the first discovery of polar mesospheric clouds after the A.D. 1883 Krakatau (Indonesia) eruption, are both consistent with levitation of ash into the mesosphere. Supervolcano eruptions are likely to inject significant quantities of charged ash into the ionosphere, resulting in disturbance or collapse of the global electrical circuit on time scales of 102 s. Because atmospheric electrical potential moderates cloud formation, large eruptions may have abrupt effects on climate through radiative forcing. Average air temperature and precipitation records from the 1883 eruption of Krakatau are consistent with a sudden effect on climate. © 2018 Geological Society of America."
"56438509000;25624545600;56438382300;45661986200;56597778200;55914196800;7103279821;","Spatio-temporal variability of warm rain events over southern West Africa from geostationary satellite observations for climate monitoring and model evaluation",2018,"10.1002/qj.3372","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053308430&doi=10.1002%2fqj.3372&partnerID=40&md5=12251422ba0d45d71c312731a8728c1c","This article presents the spatio-temporal variability of warm rain events over southern West Africa (SWA) during the summer monsoon season for the first time, using Spinning Enhanced Visible Infrared Radiometer (SEVIRI) observations on the Meteosat geostationary satellites. The delineation of warm rain events is based on the principle that precipitating low-level clouds are associated with either sufficient water content or large cloud droplet size. Capitalising on the ability of space-borne radar to resolve vertical cloud structures and detect the presence of precipitation, the delineation is trained by collocated SEVIRI and CloudSat observations. The resulting 12 years of observations from SEVIRI are used to examine the spatial, diurnal, seasonal and interannual variability of warm rain events over SWA. Warm rain events predominate during the monsoon in August, with little interannual variability, and persist over orography in the morning and the coasts after midday, likely enhanced by orographic lifting and land–sea breeze effects. Warm clouds have a much higher probability of precipitation along the coastlines of Liberia and Nigeria compared to the central SWA coastline and further inland. Finally, when evaluating an 8-day yet high-spatial resolution model simulation, we find that warm rain frequencies from the simulation agree well with SEVIRI near the coast but simulated warm cloud cover and thus warm rain frequencies are too low over the Gulf of Guinea. The probability of precipitation of warm clouds is also too low inland. The newly developed observations of warm rain create opportunities to further investigate the diurnal cycle of warm rain, study aerosol–cloud–precipitation interactions, and assess the role of warm rain in the water cycle across Africa and beyond. © 2018 Royal Meteorological Society"
"57188817814;7003875148;25631411400;7005304841;57190862175;24472110700;","Large-eddy simulation of a warm-air advection episode in the summer Arctic",2018,"10.1002/qj.3316","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055004084&doi=10.1002%2fqj.3316&partnerID=40&md5=ac3072f266243a384fcc67b1c0f7fae0","While there is an increasing scientific interest in the role of advection of warm and moist air into the Arctic, there is little understanding of the interactive processes between the advected air, boundary-layer clouds and turbulence during such events and almost all studies refer to winter conditions. We use large-eddy simulation (LES) to investigate these processes for an extreme warm-air advection episode observed during summer 2014. The results indicate that moisture advection is the critical factor for cloud formation; shutting off this supply resulted in cloud dissipation, regardless of heat advection being present or not. The dissipation of the cloud reduced the surface energy budget by up to 37 W/m2. Advection of heat suppresses cloud-driven mixing through enhancement of the atmospheric stability. Turning off the large-scale heat transport therefore resulted in a somewhat optically thicker cloud, on average increasing the liquid water path by ∼10 g/m2. The results showed little sensitivity to a number of assumptions and simplifications in the LES set-up, such as the prescribed cloud condensation nuclei concentration, friction velocity, surface albedo and the available moisture above the cloud layer. © 2018 Royal Meteorological Society"
"54894407100;57190075226;6701606453;9635764200;57095210500;","Assessing the coupled influences of clouds on the atmospheric energy and water cycles in reanalyses with a-train observations",2018,"10.1175/JCLI-D-17-0862.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054079548&doi=10.1175%2fJCLI-D-17-0862.1&partnerID=40&md5=a3ad4c6eddaceb02524e991004409311","The lack of complete knowledge concerning the complex interactions among clouds, circulation, and climate hinders our ability to simulate the Earth's climate correctly. This study contributes to a broader understanding of the implications of cloud and precipitation biases on the representation of coupled energy and water exchanges by bringing together a suite of cloud impact parameters (CIPs). These parameters measure the coupled impact of cloud systems on regional energy balance and hydrology by simultaneously capturing the absolute strength of the cloud albedo and greenhouse effects, the relative importance of these two radiative effects, and the efficiency of precipitating clouds to radiatively heat the atmosphere and cool the surface per unit of heating through rain production. Global distribution of these CIPs is derived using satellite observations from CloudSat and used to evaluate energy and water cycle coupling in four reanalysis datasets [both versions of the Modern-Era Retrospective Analysis for Research and Applications (MERRA and MERRA-2); the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim); and the Japanese 55-year Reanalysis (JRA-55)]. The results show that the reanalyses provide a more accurate representation of the three radiation-centric parameters than the radiative efficiencies. Of the four reanalyses, MERRA and ERA-Interim provide the best overall representation of the different cloud processes but can still show significant biases. JRA-55 exhibits some clear deficiencies in many parameters, while MERRA-2 seems to introduce biases that were not evident in MERRA. © 2018 American Meteorological Society."
"6506827279;7006783796;57211010680;6603546080;48662824200;55916098100;24322892500;","Calibration Changes to Terra MODIS Collection-5 Radiances for CERES Edition 4 Cloud Retrievals",2018,"10.1109/TGRS.2018.2829902","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047057789&doi=10.1109%2fTGRS.2018.2829902&partnerID=40&md5=444efd39f89be71862a07a94a4d37edb","Previous research has revealed inconsistencies between the Collection 5 (C5) calibrations of certain channels common to the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODISs). To achieve consistency between the Terra and Aqua MODIS radiances used in the Clouds and the Earth's Radiant Energy System (CERES) Edition 4 (Ed4) cloud property retrieval system, adjustments were developed and applied to the Terra C5 calibrations for channels 1-5, 7, 20, and 26. These calibration corrections, developed independently of those used for the later MODIS Collection 6 (C6), ranged from -3.0% for channel 5 to +4.3% for channel 26. For channel 20, the Terra C5 brightness temperatures were decreased nonlinearly by 0.55 K at 300-10 K or more at 220 K. The corrections were applied to the Terra C5 data for CERES Ed4 and resulted in Terra-Aqua radiance consistency that is as good as or better than that of the C6 data sets. The C5 adjustments led to more consistent Aqua and Terra cloud property retrievals than seen in the previous CERES edition. After Ed4 began processing, other calibration artifacts were found in some corrected channels and in some of the uncorrected thermal channels. Because no corrections were developed or applied for those artifacts, some anomalies or false trends could have been introduced into the Ed4 cloud property record. Thus, despite the much improved consistency achieved for the Terra and Aqua data sets in Ed4, the CERES Ed4 cloud property data sets should be used cautiously for cloud trend studies due to those remaining calibration artifacts. © 1980-2012 IEEE."
"26659013400;25624545600;7201443624;7101801476;","Characterizing the Radiative Effect of Rain Using a Global Ensemble of Cloud Resolving Simulations",2018,"10.1029/2018MS001415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055135217&doi=10.1029%2f2018MS001415&partnerID=40&md5=85c344cb7b1ae73d09fea1ca7d90fec7","The effect of rain on radiative fluxes and heating rates is a process that is neglected in most of the large scale atmospheric models used for weather forecasting or climate prediction. Yet to our knowledge, the magnitude of the resulting radiative bias remains unquantified. This study aims to quantify the rain radiative effect (RRE) at a range of temporal and spatial scales, as a step toward determining whether the radiation schemes in these models should include rain. Using off-line radiative transfer calculations with input from an ensemble of cloud resolving model simulations, we find that rain has a negligible effect on global mean radiative fluxes (less than 0.2 W m−2). Weekly mean RREs at specific locations may be larger (less than 4 W m−2). At the finest temporal and spatial resolutions, the RRE can occasionally be much larger again (greater than 100 W m−2), but values exceeding 10 W m−2 occur in less than 0.1% of cases. Using detailed analysis of case studies we demonstrate that the magnitude and direction of the RRE depend on the rain water path, its vertical location with respect to cloud, and, for longwave radiation, the temperature at which it occurs. Large RREs generally only occur when the rain water path is large and the cloud water path is small. These cases are infrequent and intermittent. As the RREs are generally small, we conclude that this missing process is unlikely to be important for large scale atmospheric models. ©2018. The Authors."
"24775103900;6602546945;57205513481;13205174000;57208550889;36083271700;56902222200;6603053832;7404751742;","Locating emergent trees in a tropical rainforest using data from an Unmanned Aerial Vehicle (UAV)",2018,"10.1016/j.jag.2018.05.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065068874&doi=10.1016%2fj.jag.2018.05.024&partnerID=40&md5=00fd84498ac64d5984ed6cd2b1c1f22a","Emergent trees, which are taller than surrounding trees with exposed crowns, provide crucial services to several rainforest species especially to endangered primates such as gibbons and siamangs (Hylobatidae). Hylobatids show a preference for emergent trees as sleeping sites and for vocal displays, however, they are under threat from both habitat modifications and the impacts of climate change. Traditional plot-based ground surveys have limitations in detecting and mapping emergent trees across a landscape, especially in dense tropical forests. In this study, a method is developed to detect emergent trees in a tropical rainforest in Sumatra, Indonesia, using a photogrammetric point cloud derived from RGB images collected using an Unmanned Aerial Vehicle (UAV). If a treetop, identified as a local maximum in a Digital Surface Model generated from the point cloud, was higher than the surrounding treetops (Trees_EM), and its crown was exposed above its neighbours (Trees_SL; assessed using slope and circularity measures), it was identified as an emergent tree, which might therefore be selected preferentially as a sleeping tree by hylobatids. A total of 54 out of 63 trees were classified as emergent by the developed algorithm and in the field. The algorithm is based on relative height rather than canopy height (due to a lack of terrain data in photogrammetric point clouds in a rainforest environment), which makes it equally applicable to photogrammetric and airborne laser scanning point cloud data. © 2018 The Authors"
"56320659600;7003907406;8225489800;57206332144;6507387688;57201413383;55584794833;56091969800;55424752100;57189501249;55962154500;7202089880;8271769900;7005165467;","Implications of whole-disc DSCOVR EPIC spectral observations for estimating earth's spectral reflectivity based on low-earth-orbiting and geostationary observations",2018,"10.3390/rs10101594","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055414820&doi=10.3390%2frs10101594&partnerID=40&md5=d3376060b50806b4632b37b59005f9e2","Earth's reflectivity is among the key parameters of climate research. National Aeronautics and Space Administration (NASA)'s Earth Polychromatic Imaging Camera (EPIC) onboard National Oceanic and Atmospheric Administration (NOAA)'s Deep Space Climate Observatory (DSCOVR) spacecraft provides spectral reflectance of the entire sunlit Earth in the near backscattering direction every 65 to 110 min. Unlike EPIC, sensors onboard the Earth Orbiting Satellites (EOS) sample reflectance over swaths at a specific local solar time (LST) or over a fixed area. Such intrinsic sampling limits result in an apparent Earth's reflectivity. We generated spectral reflectance over sampling areas using EPIC data. The difference between the EPIC and EOS estimates is an uncertainty in Earth's reflectivity. We developed an Earth Reflector Type Index (ERTI) to discriminate between major Earth atmosphere components: clouds, cloud-free ocean, bare and vegetated land. Temporal variations in Earth's reflectivity are mostly determined by clouds. The sampling area of EOS sensors may not be sufficient to represent cloud variability, resulting in biased estimates. Taking EPIC reflectivity as a reference, low-earth-orbiting-measurements at the sensor-specific LST tend to overestimate EPIC values by 0.8% to 8%. Biases in geostationary orbiting approximations due to a limited sampling area are between -0.7% and 12%. Analyses of ERTI-based Earth component reflectivity indicate that the disagreement between EPIC and EOS estimates depends on the sampling area, observation time and vary between -10% and 23%. © 2018 by the authors."
"7801602398;56593986500;8158084700;35350641800;57217282516;","Regional Climate Model Performance in Simulating Intra-seasonal and Interannual Variability of Indian Summer Monsoon",2018,"10.1007/s00024-018-1886-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054649639&doi=10.1007%2fs00024-018-1886-x&partnerID=40&md5=67b91fc4f3ddea4e4fe312c9df98d142","Establishment of Indian summer monsoon (ISM) rainfall passes through the different phases and is not uniformly distributed over the Indian subcontinent. This enhancement and reduction in daily rainfall anomaly over the Indian core monsoon region during peak monsoon season (i.e., July and August) are commonly termed as ‘active’ and ‘break’ phases of monsoon. The purpose of this study is to analyze REGional Climate Model (RegCM) results obtained using the most suitable convective parameterization scheme (CPS) to determine active/break phases of ISM. The model-simulated daily outgoing longwave radiation (OLR), mean sea level pressure (MSLP), and the wind at 850 hPa of spatial resolution of 0.5°× 0.5° are compared with NOAA, NCEP, and EIN15 data, respectively over the South-Asia Co-Ordinated Regional Climate Downscaling EXperiment (CORDEX) region. 25 years (1986–2010) composites of OLR, MSLP, and the wind at 850 hPa are considered from start to the dates of active/break phase and up to the end dates of active/break spell of monsoon. A negative/positive anomaly of OLR with active/break phase is found in simulations with CPSs Emanuel and Mix99 (Grell over land; Emanuel over ocean) over the core monsoon region as well as over Monsoon Convergence Zone (MCZ) of India. The appearance of monsoon trough during active phase over the core monsoon zone and its shifting towards the Himalayan foothills during break phase are also depicted well. Because of multi-cloud function over oceanic region and single cloud function over the land mass, the Mix99 CPSs perform well in simulating the synoptic features during the phases of monsoon. © 2018, Springer International Publishing AG, part of Springer Nature."
"57195927844;6602649973;","A study on the total cloud cover variability over the Mediterranean region during the period 1979–2014 with the use of the ERA-Interim database",2018,"10.1007/s00704-017-2276-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030178087&doi=10.1007%2fs00704-017-2276-5&partnerID=40&md5=af5d28f0876154e7e84a6ebbf43893a6","The variability and the trends of total cloud cover over the Mediterranean region are studied for the period 1979–2014, using ERA-Interim monthly 1° × 1° grid point data. A data reduction process is applied, and the main modes of inter-annual variation are found for each of the four seasons. Statistically significant positive linear trends are found only for winter over northern Italy and the northwestern Balkans, while significant negative trends are found over large parts of the region for the rest of the seasons, especially for summer. The connection between cloud cover and the large-scale atmospheric oscillations is also examined, revealing statistically significant correlations between cloud cover and the indices of the North Atlantic Oscillation, the North Sea-Caspian Pattern, the Arctic Oscillation, the Southern Oscillation, and the Eastern Atlantic/Western Russia Pattern. These connections highlight the strong dependence of the Mediterranean climate on specific characteristics of the large-scale atmospheric circulation. © 2017, Springer-Verlag GmbH Austria."
"6506258154;7102111067;36041280100;6602571316;11940634500;56330044300;7003798647;8773116800;57214957374;15072064200;","Abiotic and biotic sources influencing spring new particle formation in North East Greenland",2018,"10.1016/j.atmosenv.2018.07.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051279441&doi=10.1016%2fj.atmosenv.2018.07.019&partnerID=40&md5=369e06de81a5596eec0becdd14e22b72","In order to improve our ability to predict cloud properties, radiative balance and climate, it is crucial to understand the mechanisms that trigger the formation of new particles and their growth to activation sizes. Using an array of real time aerosol measurements, we report a categorization of the aerosol population taken at Villum Research Station, Station Nord (VRS) in North Greenland during a period of 88 days (February–May 2015). A number of New Particle Formation (NPF) events were detected and are herein discussed. Air mass back trajectories analysis plotted over snow-sea ice satellite maps allowed us to correlate early spring (April) NPF events with air masses travelling mainly over snow on land and sea ice, whereas late spring (May) NPF events were associated with air masses that have passed mainly over sea ice regions. Concomitant aerosol mass spectrometry analysis suggests methanesulfonic acid (MSA) and molecular iodine (I2) may be involved in the NPF mechanisms. The source of MSA was attributed to open leads within the sea ice. By contrast, iodine was associated with air masses over snow on land and over sea ice, suggesting both abiotic and biotic sources. Measurements of nucleating particle composition as well as gas-phase species are needed to improve our understanding of the links between emissions, aerosols, cloud and climate in the Arctic; therefore our ability to model such processes. © 2018"
"36143172200;37101562100;7005321613;","Solar signal on regional scale: A study of possible solar impact upon Romania's climate",2018,"10.1016/j.jastp.2017.09.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030467934&doi=10.1016%2fj.jastp.2017.09.015&partnerID=40&md5=bddefc9a86fc66e4edc498dfad81b69d","The topic of this paper is to investigate whether a solar signal can be identified in the variation of climatic parameters at regional scale. This was done using eight climate parameters recorded in Romania during 1961–2013 which corresponds with four cycles of solar activity. The methodology is based on trend, composite and wavelet analysis. A weak solar influence with a clear spatial pattern was identified, especially during the cold season, on temperature and cloud cover. During the warm season, the influence seems to be spurious. A clear difference between the north-eastern Romania and the rest of the country was found in the response of local climate to solar trigger. The mountain chain induces persistent disparities in the distribution of the most parameters, which supports the fact that orography is an important feature to be considered when analysing solar imprint at regional scale. Possible mechanisms for the solar influence on climate at regional and local scale are proposed. © 2017 Elsevier Ltd"
"36551067200;7004706018;6603132441;7005140533;55316399700;8135327700;55167874900;35508676000;55600933800;20434914000;57204209569;","Snow and Water Imaging Spectrometer: Mission and instrument concepts for earth-orbiting CubeSats",2018,"10.1117/1.JRS.12.044001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055006506&doi=10.1117%2f1.JRS.12.044001&partnerID=40&md5=9b733120545407df584d3e0bac06aa31","The Snow and Water Imaging Spectrometer (SWIS) is a science-grade imaging spectrometer designed for CubeSat integration, spanning a 350-to 1700-nm spectral range with 5.7-nm sampling, a 10-degree field-of-view, and 0.3-mrad spatial resolution. The system operates at F/1.8, providing the high throughput for low-reflectivity (<1%) water surfaces, while avoiding saturation over bright snow or clouds. The SWIS design utilizes heritage from previously demonstrated instruments on airborne platforms while advancing the state of the art in compact sensors of this kind in terms of size and spectral coverage. Compared with airborne campaigns, the CubeSat platform allows for more frequent and regular sampling, while maintaining intermediate to high resolution relative to heritage global sensors. Through frequent repeat observations from space at a moderate spatial resolution, SWIS can address key science questions concerning aquatic and terrestrial ecosystem changes, cryosphere warming and melt behavior, cloud and atmospheric science, and potential impacts of climate change and human activities on the environment. © 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)."
"55533168400;55745955800;57203829057;8568836700;7402170368;","Response of Tropical Terrestrial Gross Primary Production to the Super El Niño Event in 2015",2018,"10.1029/2018JG004571","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054578430&doi=10.1029%2f2018JG004571&partnerID=40&md5=aa97a253aa83f91669a85f856dc7f73c","The gross primary production (GPP) in tropical terrestrial ecosystems plays a critical role in the global carbon cycle and climate change. The strong 2015–2016 El Niño event offers a unique opportunity to investigate how GPP in the tropical terrestrial ecosystems responds to climatic forcing. This study uses two GPP products and concurrent climate data to investigate the GPP anomalies and their underlying causes. We find that both GPP products show an enhanced GPP in 2015 for the tropical terrestrial ecosystem as a whole relative to the multiyear mean of 2001–2015, and this enhancement is the net result of GPP increase in tropical forests and decrease in nonforests. We show that the increased GPP in tropical forests during the El Nino event is consistent with increased photosynthesis active radiation as a result of a reduction in clouds, while the decreased GPP in nonforests is consistent with increased water stress as a result of a reduction of precipitation and an increase of temperature. These results reveal the strong coupling of ecosystem and climate that is different in forest and nonforest ecosystems and provide a test case for carbon cycle parameterization and carbon-climate feedback simulation in models. ©2018. American Geophysical Union. All Rights Reserved."
"57192090284;6701735773;7004452524;6603875926;","Omens of coupled model biases in the CMIP5 AMIP simulations",2018,"10.1007/s00382-017-4057-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042237589&doi=10.1007%2fs00382-017-4057-3&partnerID=40&md5=908f697afe5126b030bc1742231a367d","Despite decades of efforts and improvements in the representation of processes as well as in model resolution, current global climate models still suffer from a set of important, systematic biases in sea surface temperature (SST), not much different from the previous generation of climate models. Many studies have looked at errors in the wind field, cloud representation or oceanic upwelling in coupled models to explain the SST errors. In this paper we highlight the relationship between latent heat flux (LH) biases in forced atmospheric simulations and the SST biases models develop in coupled mode, at the scale of the entire intertropical domain. By analyzing 22 pairs of forced atmospheric and coupled ocean-atmosphere simulations from the CMIP5 database, we show a systematic, negative correlation between the spatial patterns of these two biases. This link between forced and coupled bias patterns is also confirmed by two sets of dedicated sensitivity experiments with the IPSL-CM5A-LR model. The analysis of the sources of the atmospheric LH bias pattern reveals that the near-surface wind speed bias dominates the zonal structure of the LH bias and that the near-surface relative humidity dominates the east–west contrasts. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature."
"56121991900;23007626000;6701318257;55355515600;35742793700;15751354400;7006235116;","Upscaling impact of wind/sea surface temperature mesoscale interactions on southern Africa austral summer climate",2018,"10.1002/joc.5726","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052534000&doi=10.1002%2fjoc.5726&partnerID=40&md5=900fd96b69b543cb1754a5eec8b1749f","Mesoscale sea surface temperature (SST) variability plays an important role in shaping local atmospheric boundary layers through thermodynamic processes. This study focuses on the upscaling effects of mesoscale SST gradients in sensitive areas on the southern Africa regional atmospheric circulation. Using regional atmospheric model sensitivity experiments which differ only in the mesoscale SST forcing characteristics (either the full spectrum of SST variability or only its large-scale components are included), we first quantify the importance of SST gradients on regional atmospheric conditions. Agulhas eddies and meanders influence the vertical air column up to the troposphere, and mesoscale ocean patterns significantly modify incoming landwards moisture fluxes. The austral summer mean state is then modified in terms of air temperature, cloud cover and mean rainfall, with notable differences in tropical rainbands over southwestern Africa. Mesoscale SST variability favours tropical–extra-tropical interactions and cloudband development over the continent. These results stress the importance of high-resolution ocean forcing for accurate atmospheric simulations. © 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"7005034568;7402428190;55728684000;16242392800;","The AMSU-based hydrological bundle climate data record-description and comparison with other data sets",2018,"10.3390/rs10101640","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055420517&doi=10.3390%2frs10101640&partnerID=40&md5=8cc18b8e1e67703ecf06c27111f86252","Passive microwave measurements have been available on satellites back to the 1970s, first flown on research satellites developed by the National Aeronautics and Space Administration (NASA). Since then, several other sensors have been flown to retrieve hydrological products for both operational weather applications (e.g., the Special Sensor Microwave/Imager-SSM/I; the Advanced Microwave Sounding Unit-AMSU) and climate applications (e.g., the Advanced Microwave Scanning Radiometer-AMSR; the Tropical Rainfall Measurement Mission Microwave Imager-TMI; the Global Precipitation Mission Microwave Imager-GMI). Here, the focus is on measurements from the AMSU-A, AMSU-B, and Microwave Humidity Sounder (MHS). These sensors have been in operation since 1998, with the launch of NOAA-15, and are also on board NOAA-16, -17, -18, -19, and the MetOp-A and -B satellites. A data set called the ""Hydrological Bundle"" is a climate data record (CDR) that utilizes brightness temperatures from fundamental CDRs (FCDRs) to generate thematic CDRs (TCDRs). The TCDRs include total precipitable water (TPW), cloud liquid water (CLW), sea-ice concentration (SIC), land surface temperature (LST), land surface emissivity (LSE) for 23, 31, 50 GHz, rain rate (RR), snow cover (SC), ice water path (IWP), and snow water equivalent (SWE). The TCDRs are shown to be in general good agreement with similar products from other sources, such as the Global Precipitation Climatology Project (GPCP) and the Modern-Era Retrospective Analysis for Research and Applications (MERRA-2). Due to the careful intercalibration of the FCDRs, little bias is found among the different TCDRs produced from individual NOAA and MetOp satellites, except for normal diurnal cycle differences. © 2018 by the authors."
"8900751100;","Enhancement of vegetation-rainfall feedbacks on the Australian summer monsoon by the Madden–Julian Oscillation",2018,"10.1007/s00382-018-4067-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040798581&doi=10.1007%2fs00382-018-4067-9&partnerID=40&md5=9640dbdab44705419ab24443e29f5e15","A regional climate modeling analysis of the Australian monsoon system reveals a substantial modulation of vegetation-rainfall feedbacks by the Madden Julian Oscillation (MJO), both of which operate at similar sub-seasonal time scales, as evidence that the intensity of land–atmosphere interactions is sensitive to the background atmospheric state. Based on ensemble experiments with imposed modification of northern Australian leaf area index (LAI), the atmospheric responses to LAI anomalies are composited for negative and positive modes of the propagating MJO. In the regional climate model (RCM), northern Australian vegetation feedbacks are characterized by evapotranspiration (ET)-driven rainfall responses, with the moisture feedback mechanism dominating over albedo and roughness feedback mechanisms. During November–April, both Tropical Rainfall Measuring Mission and RCM data reveal MJO’s pronounced influence on rainfall patterns across northern Australia, tropical Indian Ocean, Timor Sea, Arafura Sea, and Gulf of Carpentaria, with the MJO dominating over vegetation feedbacks in terms of regulating monsoon rainfall variability. Convectively-active MJO phases support an enhancement of positive vegetation feedbacks on monsoon rainfall. While the MJO imposes minimal regulation of ET responses to LAI anomalies, the vegetation feedback-induced responses in precipitable water, cloud water, and rainfall are greatly enhanced during convectively-active MJO phases over northern Australia, which are characterized by intense low-level convergence and efficient precipitable water conversion. The sub-seasonal response of vegetation-rainfall feedback intensity to the MJO is complex, with significant enhancement of rainfall responses to LAI anomalies in February during convectively-active MJO phases compared to minimal modulation by the MJO during prior and subsequent calendar months. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature."
"16445110800;6506553245;55802221900;23012746800;","Assessment of CNRM coupled ocean-atmosphere model sensitivity to the representation of aerosols",2018,"10.1007/s00382-017-4054-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039758482&doi=10.1007%2fs00382-017-4054-6&partnerID=40&md5=8ec211af0c4a0e815f6c90044ae0c450","Atmospheric aerosols can significantly affect the Earth’s radiative balance due to absorption, scattering and aerosol-cloud interactions. Although our understanding of aerosol properties has improved over recent decades, aerosol radiative forcing remains as one of the largest uncertainties when attributing recent and projecting future anthropogenic climate change. Ensembles of a coupled ocean-atmosphere general circulation model were used to investigate how the representation of aerosols within the model can affect climate. The control simulation consisted of a 30-year simulation with an interactive aerosol scheme and aerosol emissions that evolve from 1980–2009. The sensitivity tests included using constant 1980 emissions, using prescribed 2-D monthly mean AODs, modifying the aerosol vertical distribution, altering aerosol optical properties, and changing the parameters used for calculating the aerosol first indirect effect. The results of these sensitivity studies show how modifying certain aspects of the aerosol scheme can significantly affect radiative flux and temperature. In particular, it was shown that compared to the control simulation the use of constant 1980 aerosol emissions decreased the average winter surface temperature of the Arctic by 0.2 K and that the use of prescribed 2-D monthly mean AODs reduced the annual global surface temperature by 0.3 K. Increasing the vertical distribution of anthropogenic aerosols in the model and altering aerosol optical properties modified localised radiative fluxes and temperatures, but the most significant change in global surface temperature (1.3 K) was caused by removing sea salt and organic matter from the calculation of cloud droplet number concentration. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature."
"56132618000;56329646700;7402359452;","Large-scale control of the Arabian Sea monsoon inversion in August",2018,"10.1007/s00382-017-4029-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036597291&doi=10.1007%2fs00382-017-4029-7&partnerID=40&md5=d28b2feaa30f6f136fd3477f0f85c94f","The summer monsoon inversion in the Arabian Sea is characterized by a large amount of low clouds and August as the peak season. Atmospheric stratification associated with the monsoon inversion has been considered a local system influenced by the advancement of the India–Pakistan monsoon. Empirical and numerical evidence from this study suggests that the Arabian Sea monsoon inversion is linked to a broader-scale monsoon evolution across the African Sahel, South Asia, and East Asia–Western North Pacific (WNP), rather than being a mere byproduct of the India–Pakistan monsoon progression. In August, the upper-tropospheric anticyclone in South Asia extends sideways corresponding with the enhanced precipitation in the subtropical WNP, equatorial Indian Ocean, and African Sahel while the middle part of this anticyclone weakens over the Arabian Sea. The increased heating in the adjacent monsoon systems creates a suppression effect on the Arabian Sea, suggesting an apparent competition among the Africa–Asia–WNP monsoon subsystems. The peak Sahel rainfall in August, together with enhanced heating in the equatorial Indian Ocean, produces a critical effect on strengthening the Arabian Sea thermal inversion. By contrast, the WNP monsoon onset which signifies the eastward expansion of the subtropical Asian monsoon heating might play a secondary or opposite role in the Arabian Sea monsoon inversion. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature."
"57189444016;7003476785;25634932400;56000910300;55995934700;","Land cover change and carbon stores in a tropical montane cloud forest in the Sierra Madre Oriental, Mexico",2018,"10.1007/s11629-018-4937-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054616007&doi=10.1007%2fs11629-018-4937-y&partnerID=40&md5=878d0b26e2ec2bab0a8fa4d281172527","Tropical montane cloud forest is one of the ecosystems with the highest biomass worldwide, representing an important carbon store. Globally its deforestation index is –1.1%, but in Mexico it is higher than –3%. Carbon estimates are scarce globally, particularly in Mexico. The objective of this study was to simulate future land-cover scenarios for the Sierra Madre Oriental in Mexico, by analyzing past forest cover changes. Another objective was to estimate stored carbon in the two study areas. These objectives involve the generation of information that could be useful inputs to anti-deforestation public policy such as the REDD+ strategy. Remote sensing was used to measure land cover change and estimate carbon stocks. Satellite images from 2015, 2000 and 1986 were used, and Dinamica EGO freeware generated models of future projections. Between 1986 and 2015, 5171 ha of forest were converted to pasture. The annual deforestation rates were –1.5% for Tlanchinol and –1.3% for the San Bartolo Tutotepec sites. Distance to roads and marginalization were highly correlated with deforestation. By 2030, an estimated 3608 ha of forest in these sites will have been converted to pasture. Stored carbon was estimated at 16.35 Mg C ha−1 for the Tlanchinol site and 12.7 Mg C ha−1 for the San Bartolo site. In the Sierra Madre Oriental deforestation due to land cover change (–1.4%) is higher than levels reported worldwide. Besides having high values of stored carbon (14.5 Mg C ha−1), these forests have high biodiversity. The models’ outputs show that the deforestation process will continue if action is not taken to avoid the expansion of livestock pasturing. This can be done by paying incentives for forest conservation to the owners of the land. The results suggest that REDD+ is currently the most viable strategy for reducing deforestation rates in tropical montane cloud forests in Sierra Madre Oriental. © 2018, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany, part of Springer Nature."
"56780996700;55913339000;57201394954;57201392422;57201395360;","Estimation of the Aerosol Radiative Effect over the Tibetan Plateau Based on the Latest CALIPSO Product",2018,"10.1007/s13351-018-8060-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055346437&doi=10.1007%2fs13351-018-8060-3&partnerID=40&md5=a69f515b99cf375d3779c3e9512a37f5","Based on the CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation) Version 4.10 products released on 8 November 2016, the Level 2 (L2) aerosol product over the Tibetan Plateau (TP) is evaluated and the aerosol radiative effect is also estimated in this study. As there are still some missing aerosol data points in the daytime CALIPSO Version 4.10 L2 product, this study re-calculated the aerosol extinction coefficient to explore the aerosol radiative effect over the TP based on the CALIPSO Level 1 (L1) and CloudSat 2B-CLDCLASS-LIDAR products. The energy budget estimation obtained by using the AODs (aerosol optical depths) from calculated aerosol extinction coefficient as an input to a radiative transfer model shows better agreement with the Earth’s Radiant Energy System (CERES) and CloudSat 2B-FLXHR-LIDAR observations than that with the input of AODs from aerosol extinction coefficient from CALIPSO Version 4.10 L2 product. The radiative effect and heating rate of aerosols over the TP are further simulated by using the calculated aerosol extinction coefficient. The dust aerosols may heat the atmosphere by retaining the energy in the layer. The instantaneous heating rate can be as high as 5.5 K day–1 depending on the density of the dust layers. Overall, the dust aerosols significantly affect the radiative energy budget and thermodynamic structure of the air over the TP, mainly by altering the shortwave radiation budget. The significant influence of dust aerosols over the TP on the radiation budget may have important implications for investigating the atmospheric circulation and future regional and global climate. © 2018, The Chinese Meteorological Society and Springer-Verlag GmbH Germany, part of Springer Nature."
"56225587800;57203236250;57204391317;","Detecting short-term surface melt on an Arctic glacier using UAV surveys",2018,"10.3390/rs10101547","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055449162&doi=10.3390%2frs10101547&partnerID=40&md5=a3ddb94ec4d695445db3057113e177ec","Current understanding of glacier mass balance changes under changing climate is limited by scarcity of in situ measurements in both time and space, as well as resolution of remote sensing products. Recent innovations in unmanned aerial vehicles (UAVs), as well as structure-from-motion photogrammetry (SfM), have led to increased use of digital imagery to derive topographic data in great detail in many fields, including glaciology. This study tested the capability of UAV surveys to detect surface changes over glacier ice during a three-day period in July 2016. Three UAV imaging missions were conducted during this time over 0.185 km2 of the ablation area of Fountain Glacier, NU. These were processed with the SfM algorithms in Agisoft Photoscan Professional and overall accuracies of the resulting point clouds ranged from 0.030 to 0.043 m. The high accuracy of point clouds achieved here is primarily a result of a small ground sampling distance (0.018 m), and is also influenced by GPS precision. Glacier surface change was measured through differencing of point clouds and change was compared to ablation stake measurements. Surface change measured with the UAV-SfM method agreed with the coincident ablation stake measurements in most instances, with RMSE values of 0.033, 0.028, and 0.042 m for one-, two-, and three-day periods, respectively. Total specific melt over the study area measured with the UAV was 0.170 m water equivalent (w.e.), while interpolation of ablation measurements resulted in 0.144 m w.e. Using UAVs to measure small changes in glacier surfaces will allow for new investigations of distribution of mass balance measurements. © 2018 by the authors."
"57040141000;26324818700;7408519295;56278161100;","Air temperature feedback and its contribution to global warming",2018,"10.1007/s11430-017-9226-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050672941&doi=10.1007%2fs11430-017-9226-6&partnerID=40&md5=20d0ddf9fd884bd69917dd041b6d081a","Air temperature feedback results from the thermal-radiative coupling between the atmosphere and the surface and plays an important role in surface energy balance. This paper reveals the contribution of air temperature feedback to the global warming from 1980 to 2000. The air temperature feedback kernel, evaluated using the ERA-Interim reanalysis data, is used to discuss the physical mechanism for air temperature feedback, the dependency of the strength of air temperature feedback on the climatological spatial distributions of air temperature, water vapor and cloud content, and the contributions of air temperature feedback to rapid global warming. The coupling between temperature feedback and each of the external forcings and individual feedback processes will amplify the anomaly of direct energy flux convergence at the surface induced by the external forcings and individual processes. The air temperature feedback amplifies the initial surface warming due to the increase in CO2 concentration, ice and snow melting, increase in water vapor, and change in ocean heat storage. It also amplifies the surface warming due to the longwave radiaitve forcing associated with the increase in cloud cover, which acts to suppress the cooling of the shortwave effect of cloud forcing. Overall, temperature feedback plays an important role in the global warming from 1980 to 2000, as the net positive contribution to the perturbation of global mean energy flux at the surface from the air temperature feedback is larger than the net negative contribution from external forcing and all non-temperature feedbacks. © 2018, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature."
"26026749200;57203722524;","Observed high-latitude precipitation amount and pattern and CMIP5 model projections",2018,"10.3390/rs10101583","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055417624&doi=10.3390%2frs10101583&partnerID=40&md5=f0847ef825659c2d5e5a36157f405c88","Utilizing reanalysis and high sensitivityW-band radar observations from CloudSat, this study assesses simulated high-latitude (55-82.5°) precipitation and its future changes under the RCP8.5 global warming scenario. A subset of models was selected based on the smallest discrepancy relative to CloudSat and ERA-I reanalysis using a combined ranking for bias and spatial root mean square error (RMSE). After accounting for uncertainties introduced by internal variability due to CloudSat's limited four year day-night observation period, RMSE provides greater discrimination between the models than a typical mean state bias criterion. Over 1976-2005 to 2071-2100, colder months experience larger fractional modelled precipitation increases than warmer months, and the observation-constrained models generally report a larger response than the full ensemble. For everywhere except the Southern Hemisphere (SH55, for 55-82.5°S) ocean, the selected models show greater warming than the model ensemble while their hydrological sensitivity (fractional precipitation change with temperature) is indistinguishable from the full ensemble relationship. This indicates that local thermodynamic effects explain much of the net high-latitude precipitation change. For the SH ocean, the models that perform best in the present climate show near-median warming but greater precipitation increase, implying a detectable contribution from processes other than local thermodynamic changes. A Taylor diagram analysis of the full CMIP5 ensemble finds that the Northern Hemisphere (NH55) and SH55 land areas follow a ""wet get wetter"" paradigm. The SH55 land areas show stable spatial correlations between the simulated present and future climate, indicative of small changes in the spatial pattern, but this is not true of NH55 land. This shows changes in the spatial pattern of precipitation changes through time as well as the differences in precipitation between wet and dry regions. © 2018 by the authors."
"12139043600;6507533363;6602414959;12139310900;36600036800;55682938700;57194590416;15042618500;55717074000;23051160600;16308931200;14051743300;57205638870;56250250300;","A production-tagged aerosol module for earth system models, OsloAero5.3-extensions and updates for CAM5.3-Oslo",2018,"10.5194/gmd-11-3945-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054305977&doi=10.5194%2fgmd-11-3945-2018&partnerID=40&md5=8ff41dcf31282b52846186934e121833","We document model updates and present and discuss modeling and validation results from a further developed production-Tagged aerosol module, OsloAero5.3, for use in Earth system models. The aerosol module has in this study been implemented and applied in CAM5.3-Oslo. This model is based on CAM5.3-CESM1.2 and its own predecessor model version CAM4-Oslo. OsloAero5.3 has improved treatment of emissions, aerosol chemistry, particle life cycle, and aerosol-cloud interactions compared to its predecessor OsloAero4.0 in CAM4-Oslo. The main new features consist of improved aerosol sources; the module now explicitly accounts for aerosol particle nucleation and secondary organic aerosol production, with new emissions schemes also for sea salt, dimethyl sulfide (DMS), and marine primary organics. Mineral dust emissions are updated as well, adopting the formulation of CESM1.2. The improved model representation of aerosol-cloud interactions now resolves heterogeneous ice nucleation based on black carbon (BC) and mineral dust calculated by the model and treats the activation of cloud condensation nuclei (CCN) as in CAM5.3. Compared to OsloAero4.0 in CAM4-Oslo, the black carbon (BC) mass concentrations are less excessive aloft, with a better fit to observations. Near-surface mass concentrations of BC and sea salt aerosols are also less biased, while sulfate and mineral dust are slightly more biased. Although appearing quite similar for CAM5.3-Oslo and CAM4-Oslo, the validation results for organic matter (OM) are inconclusive, since both of the respective versions of OsloAero are equipped with a limited number of OM tracers for the sake of computational efficiency. Any information about the assumed mass ratios of OM to organic carbon (OC) for different types of OM sources is lost in the transport module. Assuming that observed OC concentrations scaled by 1.4 are representative for the modeled OM concentrations, CAM5.3-Oslo with OsloAero5.3 is slightly inferior for the very sparsely available observation data. Comparing clear-sky column-integrated optical properties with data from ground-based remote sensing, we find a negative bias in optical depth globally; however, it is not as strong as in CAM4-Oslo, but has positive biases in some areas typically dominated by mineral dust emissions. Aerosol absorption has a larger negative bias than the optical depth globally. This is reflected in a lower positive bias in areas where mineral dust is the main contributor to absorption. Globally, the low bias in absorption is smaller than in CAM4-Oslo. The Ångström parameter exhibits small biases both globally and regionally, suggesting that the aerosol particle sizes are reasonably well represented. Cloud-Top droplet number concentrations over oceans are generally underestimated compared to satellite retrievals, but seem to be overestimated downwind of major emissions of dust and biomass burning sources. Finally, we find small changes in direct radiative forcing at the top of the atmosphere, while the cloud radiative forcing due to anthropogenic aerosols is now more negative than in CAM4-Oslo, being on the strong side compared to the multi-model estimate in IPCC AR5. Although not all validation results in this study show improvement for the present CAM5.3-Oslo version, the extended and updated aerosol module OsloAero5.3 is more advanced and applicable than its predecessor OsloAero4.0, as it includes new parameterizations that more readily facilitate sensitivity and process studies and use in climate and Earth system model studies in general. © 2018 Copernicus GmbH. All Rights Reserved."
"55627873255;57014496500;55980179900;57204391699;55727776500;56997948800;57204391899;57204391463;","Evaluation and intercomparison of high-resolution satellite precipitation estimates-GPM, TRMM, and CMORPH in the Tianshan Mountain Area",2018,"10.3390/rs10101543","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055457698&doi=10.3390%2frs10101543&partnerID=40&md5=aae63bd55882ca206943c47b8cea64a3","With high resolution and wide coverage, satellite precipitation products like Global Precipitation Measurement (GPM) could support hydrological/ecological research in the Tianshan Mountains, where the spatial heterogeneity of precipitation is high, but where rain gauges are sparse and unevenly distributed. Based on observations from 46 stations from 2014-2015, we evaluated the accuracies of three satellite precipitation products: GPM, Tropical Rainfall Measurement Mission (TRMM) 3B42, and the Climate Prediction Center morphing technique (CMORPH), in the Tianshan Mountains. The satellite estimates significantly correlated with the observations. They showed a northwest-southeast precipitation gradient that reflected the effects of large-scale circulations and a characteristic seasonal precipitation gradient that matched the observed regional precipitation pattern. With the highest correlation (R = 0.51), the lowest error (RMSE = 0.85 mm/day), and the smallest bias (1.27%), GPM outperformed TRMM and CMORPH in estimating daily precipitation. It performed the best at both regional and sub-regional scales and in low and mid-elevations. GPM had relatively balanced performances across all seasons, while CMORPH had significant biases in summer (46.43%) and winter (-22.93%), and TRMM performed extremely poorly in spring (R = 0.31; RMSE = 1.15 mm/day; bias = -20.29%). GPM also performed the best in detecting precipitation events, especially light and moderate precipitation, possibly due to the newly added Ka-band and high-frequency microwave channels. It successfully detected 62.09% of the precipitation events that exceeded 0.5 mm/day. However, its ability to estimate severe rainfall has not been improved as expected. Like other satellite products, GPM had the highest RMSE and bias in summer, suggesting limitations in its way of representing small-scale precipitation systems and isolated deep convection. It also underestimated the precipitation in high-elevation regions by 16%, suggesting the difficulties of capturing the orographic enhancement of rainfall associated with cap clouds and feeder-seeder cloud interactions over ridges. These findings suggest that GPM may outperform its predecessors in the mid-/high-latitude dryland, but not the tropical mountainous areas. With the advantage of high resolution and improved accuracy, the GPM creates new opportunities for understanding the precipitation pattern across the complex terrains of the Tianshan Mountains, and it could improve hydrological/ecological research in the area. © 2018 by the authors."
"56950041300;57204392570;57188723336;37003839700;57212448284;","The use of unmanned aerial vehicles to estimate direct tangible losses to residential properties from flood events: A case study of Cockermouth Following the Desmond Storm",2018,"10.3390/rs10101548","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055427489&doi=10.3390%2frs10101548&partnerID=40&md5=395d28eb86e70d9a67a5f44956d24aae","Damage caused by flood events is expected to increase in the coming decades driven by increased land use pressures and climate change impacts. The insurance sector needs accurate and efficient loss adjustment methodologies for flood events. These can include remote sensing approaches that enable the rapid estimation of (i) damage caused to property as well as (ii) the number of affected properties. Approaches based on traditional remote sensing methods have limitations associated with low-cloud cover presence, oblique viewing angles, and the resolution of the geomatic products obtained. Unmanned aerial vehicles (UAVs) are emerging as a potential tool for post-event assessment and provide a means of overcoming the limitations listed above. This paper presents a UAV-based loss-adjustment framework for the estimation of direct tangible losses to residential properties affected by flooding. For that purpose, features indicating damage to property were mapped from UAV imagery collected after the Desmond storm (5 and 6 December 2015) over Cockermouth (Cumbria, UK). Results showed that the proposed framework provided an accuracy of 84% in the detection of direct tangible losses compared with on-the-ground household-by-household assessment approaches. Results also demonstrated the importance of pluvial and, from eye witness reports, lateral flow flooding, with a total of 168 properties identified as flooded falling outside the fluvial flood extent. The direct tangible losses associated with these additional properties amounted to as high as £3.6 million. The damage-reducing benefits of resistance measures were also calculated and amounted to around £4 million. Differences in direct tangible losses estimated using the proposed UAV approach and the more classic loss-adjustment methods relying on the fluvial flood extent was around £1 million-the UAV approach providing the higher estimate. Overall, the study showed that the proposed UAV approach could make a significant contribution to improving the estimation of the costs associated with urban flooding, and responses to flooding events, at national and international levels. © 2018 by the authors."
"54408762200;57190373601;57203357423;57203353506;6603075272;14031865300;21735286000;6506435754;6603099705;57197112366;7202089880;","Estimating the leaf area of an individual tree in urban areas using terrestrial laser scanner and path length distribution model",2018,"10.1016/j.isprsjprs.2018.07.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051396404&doi=10.1016%2fj.isprsjprs.2018.07.015&partnerID=40&md5=2d2c977f19f459fa977dee8bc1deaa98","Urban leaf area measurement is crucial to properly determining the effect of urban trees on micro-climate regulation, heat island effect, building cooling, air quality improvement, and ozone formation. Previous works on the leaf area measurement have mainly focused on the stand level, although the presence of individual trees is more common than forests in urban areas. The only feasible ways for an operational non-destructive leaf area measurement, namely, optical indirect methods, are mostly limited in urban areas because light path is constantly intercepted by surrounding buildings or other objects. A terrestrial laser scanner (TLS), which can extract an individual tree by using its unique distance information, provides a possibility for indirectly measuring the leaf area index (LAI) in urban areas. However, indirect LAI measurement theory, which uses the cosine of an observation zenith angle for path-length correction, is incompatible for an individual tree because the representative projected area of LAI changes while the observation zenith angle changes, thus making the results incomparable and ambiguous. Therefore, we modified a path length distribution model for the leaf area measurement of an individual tree by replacing the traditional cosine path length correction for a continuous canopy with real path length distribution. We reconstructed the tree crown envelope from a TLS point cloud and calculated a real path length distribution through laser pulse-envelope intersections. Consequently, leaf area density was separated from the path length distribution model for leaf area calculation. Comparisons with reference measurement for an individual tree showed that the TLS-derived leaf area using the path length distribution is insensitive to the scanning resolution and agrees well with an allometric measurement with an overestimation from 5 m2 to 18 m2 (3–10%, respectively). Results from different stations are globally consistent, and using a weighted mean for different stations by sample numbers further improves the universality and efficiency of the proposed method. Further automation of the proposed method can facilitate a rapid and operational leaf area extraction of an individual tree for urban climate modeling. © 2018 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)"
"57217271893;56260361400;6507351719;","Mesoscale rainfall patterns observed around wetlands in sub-Saharan Africa",2018,"10.1002/qj.3311","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054692467&doi=10.1002%2fqj.3311&partnerID=40&md5=c44d66f53b2af7534b22ea87eee880d2","Wetlands are dynamic components of the landscape, responding to local and upstream rainfall, river flow and groundwater variability, and to water management. At the same time, in regions of strong evaporative demand, wetlands can present very strong land surface heterogeneity to the atmosphere, driving marked gradients in sensible and latent heat fluxes. At certain times of year, wetlands can therefore potentially provide a land surface feedback on rainfall. Here we assess the influence of wetlands on rainfall across sub-Saharan Africa (SSA). Using a well-established multi-satellite based product of wetland extent with monthly temporal resolution, we find significant wetland coverage (>10%) occurs at some point in the 15-year dataset for about 22% of SSA. We analyse rainfall patterns in the vicinity of major wetlands using satellite data, and find a consistent signal across SSA of locally suppressed rainfall over the wetlands as compared to nearby drier areas. This signal contrasts with a simple atmospheric water balance perspective which would suggest increased rain in response to increased local evaporation. The observed signal is strongest during the afternoon and weakens overnight. Using cloud-top temperature data from the Sahel, we find that afternoon convective initiation is favoured close to wetlands, consistent with forcing by a thermally induced circulation from gradients in sensible heat fluxes. We also find that in this region, where the vast majority of rainfall is associated with remotely triggered Mesoscale Convective Systems (MCS), convection weakens when these systems pass over wetlands. From this study, we conclude that wetlands across the range of climate zones spanning SSA influence rainfall patterns locally, and where MCS are an important component of rainfall, this influence can extend over a larger region, associated with the tracks of long-lived MCS. © 2018 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57193545401;22973021500;7402155341;57200181639;","Projected changes in summer precipitation over East Asia with a high-resolution atmospheric general circulation model during 21st century",2018,"10.1002/joc.5727","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052843805&doi=10.1002%2fjoc.5727&partnerID=40&md5=43d333ff687ea8dca04452c09b5a1f5a","We provide a broad view of East Asian summer monsoon (EASM) precipitation and their changes in the 21st century under the representative concentration pathway RCP4.5 and RCP8.5 scenarios using a high-resolution (at 40 km) atmospheric general circulation model (AGCM). The simulated fields are validated against the multiple observational data sets in the reference period (1979–2008). Validation of seasonal simulated global climatology and EASM precipitation, annual cycle and various circulation fields including 25 individual Coupled Model Intercomparison Project phase 5 (CMIP5) and CMIP5 MME suggests that AGCM can be used to study the future projected characteristics of EASM. An investigation of uncertainty in precipitation shows larger values in the regions of high-precipitation belt and low terrain. Future projections are categorized as near (2010–2039), mid (2040–2069) and far (2070–2100) futures. The model projects an increased summer precipitation of about 3.2% (2.3%) in near future, about 4.5% (4.5%) in mid-future and about 2.4% (2.3%) in far future over East Asia region under RCP4.5 (RCP8.5) scenarios when compared to the reference period. As far as regional landmasses are concerned, model projects a gradual increase in the range of 5–15% over northeast China, coastal regions of southern China, Korea and Japan regions and a decrease of about 5–10% over southeastern and northwest parts of East Asia during the 21st century. The projected increase of EASM can be attributed to an increase in atmospheric moistures (relative humidity) over the east coast of China, Korea and northeast China and north and northwestwards enhancement of eddy geopotential height. Extreme events are examined by using various precipitation indices over EASM regions. Results indicate that the indices of heavy precipitation are projected to increase (both frequency and intensity) over Korea, Japan and northeast China in the range of 5–20%, indicating strong sensitivity of EASM to global warming. © 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57204041349;7203047936;7401892219;","Comparison of TC temperature and water vapor climatologies between the Atlantic and Pacific Oceans from GPS RO observations",2018,"10.1175/JCLI-D-18-0074.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054076154&doi=10.1175%2fJCLI-D-18-0074.1&partnerID=40&md5=d0cc75eec26430db319a436622e25235","Tropical cyclone (TC) temperature and water vapor structures are essential atmospheric variables. In this study, global positioning system (GPS) radio occultation (RO) observations from the GPS RO mission named the Constellation Observing System for Meteorology, Ionosphere, and Climate and the Global Navigation Satellite System (GNSS) Receiver for Atmospheric Sounding on board both MetOp-A and MetOp-B satellites over the 9-yr period from 2007 to 2015 are used to generate a set of composite structures of temperature and water vapor fields within tropical depressions (TDs), tropical storms (TSs), and hurricanes (HUs) over the Atlantic Ocean and TDs, TSs, and typhoons (TYs) over the western Pacific Ocean. The composite TC structures are different over the two oceanic regions, reflecting different climatological environments. The warm cores for TCs over the western Pacific Ocean have higher altitudes and larger sizes than do those over the Atlantic Ocean for all storm categories. A radial variation of the warm-core temperature anomaly with descending altitude is seen, probably resulting from spiral cloud and rainband features. The large TC water vapor pressure anomalies, which are often more difficult to obtain than temperature anomalies, are located below the maximum warm-core temperature anomaly centers. Thus, the maximum values of the fractional water vapor pressure anomaly, defined as the anomaly divided by the environmental value, for TSs and HUs over the Atlantic Ocean (1.4% for TSs and 2.2% for HUs) are higher than those for TSs and TYs over the western Pacific Ocean (1.2% for TSs and 1.4% for TYs). These TC structures are obtained only after a quality control procedure is implemented, which consists of a range check that removes negative refractivity values and unrealistic temperature values, as well as a biweight check that removes data that deviate from the biweight mean by more than 3 times the biweight standard deviation. A limitation of the present study is an inability to resolve the TC inner-core structures because of a lack of sufficient RO profiles that collocate with TCs in their inner-core regions and the relatively coarse along-track resolutions of GPS RO data. © 2018 American Meteorological Society."
"57190585228;23991212200;","Effects of Explicit Convection on Land Surface Air Temperature and Land-Atmosphere Coupling in the Thermal Feedback Pathway",2018,"10.1029/2018MS001301","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054322107&doi=10.1029%2f2018MS001301&partnerID=40&md5=20488e16d158cc2e23da5ec704c87954","Simulating and understanding continental temperature extremes is a critical issue in Earth System Modeling. Conventional general circulation models are impaired by imperfect cloud and boundary layer parameterization schemes with implications for potentially unrealistic distributions of atmospheric variables and land-atmosphere coupling signals. In this study we examine a modern version of Superparameterization (SP) in the Community Atmosphere Model v.5 to examine impacts of SP on the characteristics of land surface air temperature, thermal land-atmosphere coupling, and the relationship between them. The results show that SP in the Community Atmosphere Model (SPCAM) improves mean land surface air temperature at daily time scales regionally compared to Community Atmosphere Model 5 and better simulates thermal land-atmosphere coupling (soil moisture-surface air temperature coupling) in several well-known hot spots (e.g., the Great Plains, Sahel, and India). Detailed analysis of regional probability distribution functions reveals how the intrinsic relationships of atmosphere variables, land-atmosphere coupling, and temperature extremes are modified by SP. Regression-type metrics are also used to examine global land-atmosphere coupling, with some expected limitations where multiple coupling regimes coexist temporally. Stratifying results by soil moisture percentile proves illuminating in this regard and reveals that SP frequently amplifies land-atmosphere thermal coupling at the dry end of regional coupling regimes. ©2018. The Authors."
"57200336864;7401574475;42761639100;","Metric-dependent tendency of tropical belt width changes during the last glacial maximum",2018,"10.1175/JCLI-D-18-0199.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054087287&doi=10.1175%2fJCLI-D-18-0199.1&partnerID=40&md5=d87f83170f78a66dc7c70f9da439c861","Motivated by studies of tropical expansion under modern global warming, the behavior of the tropical belt during the Last Glacial Maximum (LGM) relative to the preindustrial period has been investigated in this study, using simulations from phase 3 of the Paleoclimate Modelling Intercomparison Project (PMIP3) under the framework of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The tropical belt width changes determined by multiple metrics present two opposite tendencies. One refers to the poleward migration of the tropical edge as measured by the steep tropopause gradient and the subtropical jet, and the other suggests that the LGM tropics become narrower as measured by the Hadley cell extent, the eddy-driven jet, and the latitude where precipitation minus evaporation equals zero. The magnitude of such changes widely differs across models and metrics. In absolute terms, the multimodel mean total width changes range from 0.6° to 1.7° among metrics, with contributions predominantly from the Northern Hemisphere. Furthermore, the two metrics that indicate tropical widening are located in the upper troposphere. Such widening is closely related to the vertical and meridional temperature gradient changes in the subtropical regions. The other metrics are located in the middle and lower troposphere, and their variations are directly or indirectly related to changes in the low-level baroclinicity. The diverse responses of metrics to the LGM boundary conditions suggest that the tropical belt width changes and their climatic impacts are distinguished by the different measurements. The selection of metrics should correspond to the specific tropical properties of concern. © 2018 American Meteorological Society."
"56108583200;7003377229;15755848100;26431291300;6504520419;48362105200;7006060239;13613779300;8667081700;7004377842;8719649000;8645964400;","Navigating snowscapes: scale-dependent responses of mountain sheep to snowpack properties",2018,"10.1002/eap.1773","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054083768&doi=10.1002%2feap.1773&partnerID=40&md5=3a9f01338b09fdca186acdf422719c21","Winters are limiting for many terrestrial animals due to energy deficits brought on by resource scarcity and the increased metabolic costs of thermoregulation and traveling through snow. A better understanding of how animals respond to snow conditions is needed to predict the impacts of climate change on wildlife. We compared the performance of remotely sensed and modeled snow products as predictors of winter movements at multiple spatial and temporal scales using a data set of 20,544 locations from 30 GPS-collared Dall sheep (Ovis dalli dalli) in Lake Clark National Park and Preserve, Alaska, USA from 2005 to 2008. We used daily 500-m MODIS normalized difference snow index (NDSI), and multi-resolution snow depth and density outputs from a snowpack evolution model (SnowModel), as covariates in step selection functions. We predicted that modeled snow depth would perform best across all scales of selection due to more informative spatiotemporal variation and relevance to animal movement. Our results indicated that adding any of the evaluated snow metrics substantially improved model performance and helped characterize winter Dall sheep movements. As expected, SnowModel-simulated snow depth outperformed NDSI at fine-to-moderate scales of selection (step scales < 112 h). At the finest scale, Dall sheep selected for snow depths below mean chest height (<54 cm) when in low-density snows (100 kg/m3), which may have facilitated access to ground forage and reduced energy expenditure while traveling. However, sheep selected for higher snow densities (>300 kg/m3) at snow depths above chest height, which likely further reduced energy expenditure by limiting hoof penetration in deeper snows. At moderate-to-coarse scales (112–896 h step scales), however, NDSI was the best-performing snow covariate. Thus, the use of publicly available, remotely sensed, snow cover products can substantially improve models of animal movement, particularly in cases where movement distances exceed the MODIS 500-m grid threshold. However, remote sensing products may require substantial data thinning due to cloud cover, potentially limiting its power in cases where complex models are necessary. Snowpack evolution models such as SnowModel offer users increased flexibility at the expense of added complexity, but can provide critical insights into fine-scale responses to rapidly changing snow properties. © 2018 by the Ecological Society of America"
"55558809100;54400559100;6603400519;55688930000;57207228835;7006705919;","Climatic Responses to Future Trans-Arctic Shipping",2018,"10.1029/2018GL078969","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054074555&doi=10.1029%2f2018GL078969&partnerID=40&md5=19567c8436518e6669763fcd177b4626","As global temperatures increase, sea ice loss will increasingly enable commercial shipping traffic to cross the Arctic Ocean, where the ships' gas and particulate emissions may have strong regional effects. Here we investigate impacts of shipping emissions on Arctic climate using a fully coupled Earth system model (CESM 1.2.2) and a suite of newly developed projections of 21st-century trans-Arctic shipping emissions. We find that trans-Arctic shipping will reduce Arctic warming by nearly 1 °C by 2099, due to sulfate-driven liquid water cloud formation. Cloud fraction and liquid water path exhibit significant positive trends, cooling the lower atmosphere and surface. Positive feedbacks from sea ice growth-induced albedo increases and decreased downwelling longwave radiation due to reduced water vapor content amplify the cooling relative to the shipping-free Arctic. Our findings thus point to the complexity in Arctic climate responses to increased shipping traffic, justifying further study and policy considerations as trade routes open. ©2018. The Authors."
"24168416900;7103016965;8723504500;57194400515;55913183200;7402989545;7801353107;24764483400;18635820300;","Cloud Microphysical Factors Affecting Simulations of Deep Convection During the Presummer Rainy Season in Southern China",2018,"10.1029/2017JD028192","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053564039&doi=10.1029%2f2017JD028192&partnerID=40&md5=33daa75b81800e00bfb174f2e9c91b68","The sensitivity of subtropical deep convection to the parameterization of cloud microphysics is elucidated through high-resolution modeling of extreme presummer rainfall over southern China. An ensemble of physics configuration experiments is used to identify several drivers of model errors in comparison to radar observations from the South China Monsoon Rainfall Experiment (SCMREX) and remotely sensed estimates of cloud, precipitation, and radiation from satellites in the A-train constellation. The benefits of increasing the number of prognostic variables in the microphysics scheme is assessed, relative to the effects of the parameterization of cloud microphysical properties and cloud fraction diagnosis. By matching individual parameterizations between the microphysical configurations, it is shown that a small subset of the parameterization changes can reproduce most of the dependence of model performance on physics configuration. In particular, biases that are due to the low-level clouds and rain are strongly influenced by cloud fraction diagnosis and raindrop size distribution, whereas variations in the effects of high clouds are strongly influenced by differences in the parameterization of ice crystal sedimentation. Hence, for the case studied here, these parameterizations give more insight into the causes of variability in model performance than does the number of model prognostics per se. ©2018. American Geophysical Union. All Rights Reserved."
"56612517400;6701562113;","Precipitation Partitioning in Multiscale Atmospheric Simulations: Impacts of Stability Restoration Methods",2018,"10.1029/2018JD028710","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053554212&doi=10.1029%2f2018JD028710&partnerID=40&md5=bc1c56376388787a598ecd3f2401a596","Proper simulation of high-resolution surface precipitation distribution and variability is important to local aspects of environmental pollution and climate. Global and regional climate and weather models routinely evaluate total precipitation using available measurements, but quantitative evaluation of contributions by the individual components (convective and nonconvective) to the total precipitation is not routinely performed. Wet bias in one component can alleviate dry bias in the other component, making the total precipitation look comparable to measurements, leading to an invisible bias. To study this aspect, Tropical Rainfall Measuring Mission (TRMM) measurements for precipitation components were used to quantitatively evaluate convective fractions simulated by a cumulus parameterization scheme in a regional climate simulation using 12-km grid spacing. Results indicated a wet bias in convective precipitation as compared to TRMM measurements. This wet bias helped to counter a dry bias in grid-scale precipitation and led to a total precipitation comparable to Parameter-elevation Regressions on Independent Slopes Model and TRMM measurements. A new formulation has been developed for convective cloud adjustment time scale alleviating wet bias in convective precipitation when compared to the old formulation and TRMM measurements. Results for different grid spacing also indicate that the new method produces lower subgrid-scale precipitation with overall better precipitation estimates. Our results also suggest that evaluating both components of the surface precipitation rather than just the total itself can inform a need to improve cloud formulations, as demonstrated in this study. This study calls for the development of methods to routinely produce measurements for precipitation components that help evaluating global and regional climate and weather models. Published 2018. This article is a US Government work and is in the public domain in the USA."
"56014511300;38561188200;57204505890;","The global warming potential of near-surface emitted water vapour",2018,"10.1088/1748-9326/aae018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055827530&doi=10.1088%2f1748-9326%2faae018&partnerID=40&md5=fe66e4880716f4f3d536c2f57099a8f2","Water vapour is the most abundant and powerful greenhouse gas in Earth's atmosphere, and is emitted by human activities. Yet the global warming potential (GWP) and radiative forcing (RF) of emitted water vapour have not been formally quantified in the literature. Here these quantities are estimated for surface emission using idealised experiments conducted with the CAM5 global atmospheric model at fixed ocean temperatures. Water is introduced in vapour form at rates matching total anthropogenic emissions (mainly from irrigation) but omitting the local evaporative cooling seen in irrigation simulations. A 100 year GWP for H2O of -10-3 to 5 × 10-4 is found, and an effective radiative forcing of -0.1 to 0.05 W m-2 for the given emissions. Increases in water vapour greenhouse effect are small because additional vapour cannot reach the upper troposphere, and greenhouse-gas warming is outweighed by increases in reflectance from humidity-induced low cloud cover, leading to a near-zero or small cooling effect. Near-surface temperature decreases over land are implied even without evaporative cooling at the surface, due to cooling by low clouds and vapour-induced changes to the moist lapse rate. These results indicate that even large increases in anthropogenic water vapour emissions would have negligible warming effects on climate, but that possible negative RF may deserve more attention. © 2018 The Author(s). Published by IOP Publishing Ltd."
"26323066900;35742922300;6602845217;25723647800;","An ensemble of AMIP simulations with prescribed land surface temperatures",2018,"10.5194/gmd-11-3865-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054082692&doi=10.5194%2fgmd-11-3865-2018&partnerID=40&md5=281bef0c10fcd8124a16fab8757c7eaf","General circulation models (GCMs) are routinely run under Atmospheric Modelling Intercomparison Project (AMIP) conditions with prescribed sea surface temperatures (SSTs) and sea ice concentrations (SICs) from observations. These AMIP simulations are often used to evaluate the role of the land and/or atmosphere in causing the development of systematic errors in such GCMs. Extensions to the original AMIP experiment have also been developed to evaluate the response of the global climate to increased SSTs (prescribed) and carbon dioxide (CO2) as part of the Cloud Feedback Model Intercomparison Project (CFMIP). None of these international modelling initiatives has undertaken a set of experiments where the land conditions are also prescribed, which is the focus of the work presented in this paper. Experiments are performed initially with freely varying land conditions (surface temperature, and soil temperature and moisture) under five different configurations (AMIP, AMIP with uniform 4 K added to SSTs, AMIP SST with quadrupled CO2, AMIP SST and quadrupled CO2 without the plant stomata response, and increasing the solar constant by 3.3 %). Then, the land surface temperatures from the free land experiments are used to perform a set of Ice nucleating particles (INPs) increase the temperature at which supercooled droplets start to freeze. They are therefore of particular interest in mixed-phase cloud temperature regimes, where supercooled liquid droplets can persist for extended periods of time in the absence of INPs. When INPs are introduced to such an environment, the cloud can quickly glaciate following ice multiplication processes and the Wegener-Bergeron-Findeisen (WBF) process. The WBF process can also cause the ice to grow to precipitation size and precipitate out. All of these processes alter the radiative properties. Despite their potential influence on climate, the ice nucleation ability and importance of different aerosol species is still not well understood and is a field of active research. In this study, we use the aerosol-climate model ECHAM6-HAM2 to examine the global relevance of marine organic aerosol (MOA), which has drawn much interest in recent years as a potentially important INPs in remote marine regions. We address the uncertainties in emissions and ice nucleation activity of MOA with a range of reasonable set-ups and find a wide range of resulting MOA burdens. The relative importance of MOA as an INP compared to dust is investigated and found to depend strongly on the type of ice nucleation parameterisation scheme chosen. On the zonal mean, freezing due to MOA leads to relative increases in the cloud ice occurrence and in-cloud number concentration close to the surface in the polar regions during summer. Slight but consistent decreases in the in-cloud ice crystal effective radius can also be observed over the same regions during all seasons. Regardless, MOA was not found to affect the radiative balance significantly on the global scale, due to its relatively weak ice activity and a low sensitivity of cloud ice properties to heterogeneous ice nucleation in our model.AMIP prescribed land
(PL) simulations, which are evaluated against their free land counterparts. The PL simulations agree well with the free land experiments, which indicates that the land surface is prescribed in a way that is consistent with the original free land configuration. Further experiments are also performed with different combinations of SSTs, CO2 concentrations, solar constant and land conditions. For example, SST and land conditions are used from the AMIP simulation with quadrupled CO2 in order to simulate the atmospheric response to increased CO2 concentrations without the surface temperature changing. The results of all these experiments have been made publicly available for further analysis. The main aims of this paper are to provide a description of the method used and an initial validation of these AMIP prescribed land experiments. © Crown copyright 2018."
"56594940700;7006747377;9535830600;","Reanalysis intercomparisons of stratospheric polar processing diagnostics",2018,"10.5194/acp-18-13547-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054076880&doi=10.5194%2facp-18-13547-2018&partnerID=40&md5=17dcb5b732758e7cca27d70c937730fb","We compare herein polar processing diagnostics derived from the four most recent full-input reanalysis datasets: the National Centers for Environmental Prediction Climate Forecast System Reanalysis/Climate Forecast System, version 2 (CFSR/CFSv2), the European Centre for Medium-Range Weather Forecasts Interim (ERA-Interim) reanalysis, the Japanese Meteorological Agency's 55-year (JRA-55) reanalysis, and the National Aeronautics and Space Administration (NASA) Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2). We focus on diagnostics based on temperatures and potential vorticity (PV) in the lower-to-middle stratosphere that are related to formation of polar stratospheric clouds (PSCs), chlorine activation, and the strength, size, and longevity of the stratospheric polar vortex. Polar minimum temperatures (T min) and the area of regions having temperatures below PSC formation thresholds (A PSC) show large persistent differences between the reanalyses, especially in the Southern Hemisphere (SH), for years prior to 1999. Average absolute differences of the reanalyses from the reanalysis ensemble mean (REM) in T min are as large as 3 K at some levels in the SH (1.5 K in the Northern Hemisphere-NH), and absolute differences of reanalysis A PSC from the REM up to 1.5 % of a hemisphere (0.75 % of a hemisphere in the NH). After 1999, the reanalyses converge toward better agreement in both hemispheres, dramatically so in the SH: average T min differences from the REM are generally less than 1 K in both hemispheres, and average A PSC differences less than 0.3 % of a hemisphere. The comparisons of diagnostics based on isentropic PV for assessing polar vortex characteristics, including maximum PV gradients (MPVGs) and the area of the vortex in sunlight (or sunlit vortex area, SVA), show more complex behavior: SH MPVGs showed convergence toward better agreement with the REM after 1999, while NH MPVGs differences remained largely constant over time; differences in SVA remained relatively constant in both hemispheres. While the average differences from the REM are generally small for these vortex diagnostics, understanding such differences among the reanalyses is complicated by the need to use different methods to obtain vertically resolved PV for the different reanalyses. We also evaluated other winter season summary diagnostics, including the winter mean volume of air below PSC thresholds, and vortex decay dates. For the volume of air below PSC thresholds, the reanalyses generally agree best in the SH, where relatively small interannual variability has led to many winter seasons with similar polar processing potential and duration, and thus low sensitivity to differences in meteorological conditions among the reanalyses. In contrast, the large interannual variability of NH winters has given rise to many seasons with marginal conditions that are more sensitive to reanalysis differences. For vortex decay dates, larger differences are seen in the SH than in the NH; in general, the differences in decay dates among the reanalyses follow from persistent differences in their vortex areas. Our results indicate that the transition from the reanalyses assimilating Tiros Operational Vertical Sounder (TOVS) data to advanced TOVS and other data around 1998-2000 resulted in a profound improvement in the agreement of the temperature diagnostics presented (especially in the SH) and to a lesser extent the agreement of the vortex diagnostics. We present several recommendations for using reanalyses in polar processing studies, particularly related to the sensitivity to changes in data inputs and assimilation. Because of these sensitivities, we urge great caution for studies aiming to assess trends derived from reanalysis temperatures. We also argue that one of the best ways to assess the sensitivity of scientific results on polar processing is to use multiple reanalysis datasets. © 2018 Author(s)."
"56440802100;55324277300;8516206500;","A weekly, continually updated dataset of the probability of large wildfires across western US forests and woodlands",2018,"10.5194/essd-10-1715-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053902211&doi=10.5194%2fessd-10-1715-2018&partnerID=40&md5=4da8fa568334617fa66dc42c61094b5c","There is broad consensus that wildfire activity is likely to increase in western US forests and woodlands over the next century. Therefore, spatial predictions of the potential for large wildfires have immediate and growing relevance to near-and long-term research, planning, and management objectives. Fuels, climate, weather, and the landscape all exert controls on wildfire occurrence and spread, but the dynamics of these controls vary from daily to decadal timescales. Accurate spatial predictions of large wildfires should therefore strive to integrate across these variables and timescales. Here, we describe a high spatial resolution dataset (250 m pixel) of the probability of large wildfires (> 405 ha) across forests and woodlands in the contiguous western US, from 2005 to the present. The dataset is automatically updated on a weekly basis using Google Earth Engine and a continuous integration/q pipeline. Each image in the dataset is the output of a random forest machine-learning algorithm, trained on random samples of historic small and large wildfires and represents the predicted conditional probability of an individual pixel burning in a large fire, given an ignition or fire spread to that pixel. This novel workflow is able to integrate the near-term dynamics of fuels and weather into weekly predictions while also integrating longer-term dynamics of fuels, the climate, and the landscape. As a continually updated product, the dataset can provide operational fire managers with contemporary, on-the-ground information to closely monitor the changing potential for large wildfire occurrence and spread. It can also serve as a foundational dataset for longer-term planning and research, such as the strategic targeting of fuels management, fire-smart development at the wildland-urban interface, and the analysis of trends in wildfire potential over time. large fire probability GeoTiff products from 2005 to 2017 are archived on the Figshare online digital repository with the DOI https://doi.org/10.6084/m9.figshare.5765967 (available at https://doi.org/10.6084/m9.figshare.5765967.v1). Weekly GeoTiff products and the entire dataset from 2005 onwards are also continually uploaded to a Google Cloud Storage bucket at https://console.cloud.google.com/storage/wffr-preds/V1 (last access: 14 September 2018) and are available free of charge with a Google account. Continually updated products and the long-term archive are also available to registered Google Earth Engine (GEE) users as public GEE assets and can be accessed with the image collection ID ""users/mgray/wffr-preds"" within GEE. © 2018 Author(s)."
"57097508000;7006041988;7003663305;","Observed aerosol suppression of cloud ice in low-level Arctic mixed-phase clouds",2018,"10.5194/acp-18-13345-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053710592&doi=10.5194%2facp-18-13345-2018&partnerID=40&md5=a587a1316cee267bb54de918823b3f25","The interactions that occur between aerosols and a mixed-phase cloud system, and the subsequent alteration of the microphysical state of such clouds, are a problem that has yet to be well constrained. Advancing our understanding of aerosol-ice processes is necessary to determine the impact of natural and anthropogenic emissions on Earth's climate and to improve our capability to predict future climate states. This paper deals specifically with how aerosols influence ice mass production in low-level Arctic mixed-phase clouds. In this study, a 9-year record of aerosol, cloud and atmospheric state properties is used to quantify aerosol influence on ice production in mixed-phase clouds. It is found that mixed-phase clouds present in a clean aerosol state have higher ice water content (IWC) by a factor of 1.22 to 1.63 at cloud base than do similar clouds in cases with higher aerosol loading. We additionally analyze radar-derived mean Doppler velocities to better understand the drivers behind this relationship, and we conclude that aerosol induced reduction of the ice crystal nucleation rate, together with decreased riming rates in polluted clouds, are likely influences on the observed reductions in IWC. © Author(s) 2018."
"57203962984;57189225001;56490302800;6602115068;","Quantifying the single-scattering albedo for the January 2017 Chile wildfires from simulations of the OMI absorbing aerosol index",2018,"10.5194/amt-11-5261-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053781530&doi=10.5194%2famt-11-5261-2018&partnerID=40&md5=f21358c95e1735c2ba0483b82fa2c3ed","The absorbing aerosol index (AAI) is a qualitative parameter directly calculated from satellite-measured reflectance. Its sensitivity to absorbing aerosols in combination with a long-term data record since 1978 makes it an important parameter for climate research. In this study, we attempt to quantify aerosol absorption by retrieving the single-scattering albedo (ω0) at 550 nm from the satellite-measured AAI. In the first part of this study, AAI sensitivity studies are presented exclusively for biomass-burning aerosols. Later on, we employ a radiative transfer model (DISAMAR) to simulate the AAI measured by the Ozone Monitoring Instrument (OMI) in order to derive ω0 at 550 nm. Inputs for the radiative transfer calculations include satellite measurement geometry and surface conditions from OMI, aerosol optical thickness (τ) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and aerosol microphysical parameters from the AErosol RObotic NETwork (AERONET), respectively. This approach is applied to the Chile wildfires for the period from 26 to 30 January 2017, when the OMI-observed AAI of this event reached its peak. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) overpasses missed the evolution of the smoke plume over the research region; therefore the aerosol profile is parameterized. The simulated plume is at an altitude of 4.5-4.9 km, which is in good agreement with available CALIOP backscatter coefficient measurements. The data may contain pixels outside the plume, so an outlier detection criterion is applied. The results show that the AAI simulated by DISAMAR is consistent with satellite observations. The correlation coefficients fall into the range between 0.85 and 0.95. The retrieved mean ω0 at 550 nm for the entire plume over the research period from 26 to 30 January 2017 varies from 0.81 to 0.87, whereas the nearest AERONET station reported ω0 between 0.89 and 0.92. The difference in geolocation between the AERONET site and the plume, the assumption of homogeneous plume properties, the lack of the aerosol profile information and the uncertainties in the inputs for radiative transfer calculation are primarily responsible for this discrepancy in ω0. © Author(s) 2018."
"55458732800;56230211700;6701592014;14019399400;7006246996;","Cloud Optical Properties Over West Antarctica From Shortwave Spectroradiometer Measurements During AWARE",2018,"10.1029/2018JD028347","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052851071&doi=10.1029%2f2018JD028347&partnerID=40&md5=2e7ded7ac3433b7b5b8899eb9a4c85dd","A shortwave spectroradiometer was deployed on the West Antarctic Ice Sheet (WAIS) as part of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program ARM West Antarctic Radiation Experiment (AWARE). This instrument recorded 1-min averages of downwelling hemispheric spectral irradiance covering the wavelength range 350–2,200 nm with spectral resolution 3 and 10 nm for wavelengths shorter and longer than 1,000 nm, respectively. Using simultaneous micropulse lidar data to identify the thermodynamic phase of stratiform clouds, a radiative transfer algorithm is used to retrieve optical depth and effective droplet (or particle) size for single-phase liquid water and ice water clouds. The AWARE campaign on the WAIS first sampled typical climatological conditions between 7 December 2015 and 9 January 2016 and then a much warmer air mass with more moisture associated with a surface melt event between 10 and 17 January 2016. Before the melt event most liquid cloud effective droplet radii were consistent with pristine polar maritime clouds (mode radius 13.5 μm) but showed a second local maximum in the distribution (at 8 μm) consistent with colder, moisture-limited conditions. Most ice clouds sampled occurred before the melt event (mode optical depth 4 and effective particle size 19 μm). During the melt event liquid water cloud optical depth nearly doubled (mode value increasing from 8 to 14). AWARE therefore sampled on the WAIS two cases relevant to climate model simulations: typical current climatological conditions, followed by warmer meteorology possibly consistent with future increasing surface melt scenarios. ©2018. American Geophysical Union. All Rights Reserved."
"55669579000;57196143493;","The Radiative Feedback During the ENSO Cycle: Observations Versus Models",2018,"10.1029/2018JD028401","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052852973&doi=10.1029%2f2018JD028401&partnerID=40&md5=90d52d29895306c9eb95f08b9e8be85d","Observational and model data are used to study the radiative feedbacks during the El Niño–Southern Oscillation (ENSO) cycle. We extend the previous works by analyzing the feedbacks with respect to not only top-of-atmosphere (TOA) but also the surface and atmospheric radiation budgets, using a newly developed set of radiation kernels. We find that the tropical radiative budgets undergo distinctive variations during ENSO. The radiative perturbation is especially significant for the atmospheric energy budget. We find that the cloud feedback during the developing phase of ENSO heats the atmosphere over the west and central Pacific differentially, which acts to strengthen the development. We also find that a prominent cloud feedback bias persists in the newer version global climate models. This bias results from wrong extent of compensation between longwave and shortwave effects, which points to the importance of validating the radiative sensitivity of clouds in the general circulation models. ©2018. American Geophysical Union. All Rights Reserved."
"55871347000;7004060399;","Ocean Circulation Reduces the Hadley Cell Response to Increased Greenhouse Gases",2018,"10.1029/2018GL079070","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053404716&doi=10.1029%2f2018GL079070&partnerID=40&md5=3ab06471c71eb842bfc58317dedf6fca","The Hadley cell (HC) plays an important role in setting the strength and position of the hydrological cycle. Climate projections show a weakening of the HC, together with widening of its vertical and meridional extents. These changes are projected to have profound global climatic impacts. Current theories for the HC response to increased greenhouse gases account only for atmospheric and oceanic thermodynamic changes and not for oceanic circulation changes. Here the effects of ocean circulation changes on the HC response to increased greenhouse gases are examined by comparing fully coupled and slab ocean model configurations. By reducing the warming of both the sea surface and the atmosphere, changes in ocean circulation reduce the HC response to increased CO2 concentrations. This reduced warming suppresses convective heating, which reduces the weakening of the HC and the stabilization at low latitudes, and thus also reduces the meridional (in the Southern Hemisphere) and vertical HC expansion. ©2018. American Geophysical Union. All Rights Reserved."
"57203866755;36809017200;7004647146;55623265200;9246029600;","Sources of Uncertainty in the Meridional Pattern of Climate Change",2018,"10.1029/2018GL079429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053273714&doi=10.1029%2f2018GL079429&partnerID=40&md5=2a8514fa1dd147a87bb3d5026f56d459","We employ a moist energy balance model (MEBM), representing atmospheric heat transport as the diffusion of near-surface moist static energy, to evaluate sources of uncertainty in the meridional pattern of surface warming. Given zonal mean patterns of radiative forcing, radiative feedbacks, and ocean heat uptake, the MEBM accurately predicts zonal mean warming as simulated by general circulation models under increased CO2. Over a wide range of latitudes, the MEBM captures approximately 90% of the variance in zonal mean warming across the general circulation models, with approximately 70% of the variance attributable to differences in radiative feedbacks alone. Partitioning the radiative feedbacks into individual components shows that the majority of the uncertainty in the meridional pattern of warming arises from uncertainty in cloud feedbacks. Isolating feedback uncertainty within specific regions demonstrates that tropical feedback uncertainty leads to surface warming uncertainty that is global and nearly uniform with latitude, whereas polar feedback uncertainty leads to surface warming uncertainty that is largely confined to the poles. ©2018. American Geophysical Union. All Rights Reserved."
"7202081585;6505932008;55682851300;","The Life Cycles of Ice Crystals Detrained From the Tops of Deep Convection",2018,"10.1029/2018JD028832","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052959333&doi=10.1029%2f2018JD028832&partnerID=40&md5=51b16bc958f964c06d4542a7bc31ea39","Extensive anvil cirrus clouds generated by deep convection have important impacts on the Earth's radiation budget and climate. We use growth-sedimentation trajectory calculations to investigate the life cycles of anvil ice crystals as they are advected downwind from their convective source. Temperature, water vapor, and wind fields from a cloud-resolving model simulation of an isolated cumulonimbus cloud are used to drive the calculations. Ice crystals are initialized in the main upper-level detrainment zone with a size distribution based on in situ measurements made in a convective core at about 12 km. Advection, deposition growth, and sedimentation of thousands of sample ice crystals are tracked over about 2.5 hr; neither aggregation of ice crystals nor radiative effects are included. Results support the importance of deposition growth and gravitational size sorting in the evolution of the anvil cirrus. Most ice crystals initialized with maximum dimensions larger than about 200 μm fall out of the anvil and sublimate in subsaturated air below within about 2 hr. Few small ice crystals are present in the lower part of the mature anvil. Vapor deposition growth accounts for about 50% of the ice mass remaining after about 2 hr. Ice crystals larger than about 50 μm in the mature anvil have grown substantially by deposition of vapor. This result is consistent with the predominance of bullet rosette habits observed in mature anvils. Variations in ice crystal fall speeds and growth rates associated with ice crystal habit assumptions have little impact on the ice crystal life cycles. ©2018. American Geophysical Union. All Rights Reserved."
"57193160422;55619475000;8653276300;9249656500;57211224269;13404531500;8908558300;56797095600;7004696243;","Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum",2018,"10.1029/2017JD028017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053410932&doi=10.1029%2f2017JD028017&partnerID=40&md5=520575d2daf858f8e19144ba414a4e2c","The impact of changes in the stratospheric ozone profile in the Last Glacial Maximum simulation under reduced atmospheric CO2 concentrations and different orbital elements is investigated using an Earth System Model. For this, simulations including an interactive atmospheric chemistry scheme is compared with simulations using the prescribed ozone profile for a preindustrial control run of the fifth Coupled Model Intercomparison Project (CMIP5). The contribution of the interactive chemistry reveals a significant warming of zonal mean surface temperature, +0.5 K (approximately 20%) in the tropics and up to +1.6 K in high latitudes. In the tropics, this mitigation of global cooling is related to longwave radiative feedbacks associated with circulation-driven increases in the lower stratospheric ozone and in the stratospheric water vapor, and related decrease in cirrus clouds. The mechanisms are of opposite sign to and consistent with those obtained by increased CO2 simulations. In high latitude, the stronger mitigation of cooling is associated with sea ice retreat, which has the same sign to and is consistent with our previous paleoclimate simulation of the mid-Holocene (CO2 concentration of 280 ppm and orbital element change) including interactive chemistry. Most previous Last Glacial Maximum simulations with the prescribed ozone profile exhibited cold bias in the tropics compared with geological proxy data, whereas this bias is reduced in our simulations through the use of the interactive ozone chemistry, although a warmer bias in the midlatitude is enhanced. We recommend climate models to include ozone profiles that are consistent with CO2 concentrations and solar forcing. ©2018. American Geophysical Union. All Rights Reserved."
"57097516200;55041627100;36538539800;7403961319;6506877845;57201024134;24074765200;6602420251;","Modeling of Atmospheric Aerosol Properties in the São Paulo Metropolitan Area: Impact of Biomass Burning",2018,"10.1029/2018JD028768","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053403984&doi=10.1029%2f2018JD028768&partnerID=40&md5=ec65a65f96f1003e414b9e5acae9b6d1","Smoke particles ejected into the atmosphere from biomass burning can modify the atmospheric composition around and even far from the sources. In late winter and early spring, biomass burning emissions from inland regions can be efficiently transported to urban areas in southeastern South America, thus affecting air quality in those areas. In this study, the Weather Research and Forecasting with Chemistry model was applied in order to investigate the impact of biomass burning sources on aerosol loadings and properties over the São Paulo Metropolitan Area (SPMA), in southeastern Brazil, during the period from 19 August to 3 September 2014. The model performance was evaluated using available aerosol measurements from the Narrowing the Uncertainties on Aerosol and Climate Change in São Paulo State project. The combined application of aerosol data and Weather Research and Forecasting with Chemistry simulations made it possible to represent some of the most important aerosol properties, such as particle number concentration and cloud condensation nuclei activation, in addition to evaluation of the impact of biomass burning by analyzing a 5-day transport event, from 22 to 26 August 2014. During this transport event, differences in the average predicted PM2.5 concentration reached 15 μg/m3 (peaking at 20 μg/m3 during the nighttime hours) over the SPMA, compared with 35 μg/m3 over inland areas northwest and north of the SPMA. Biomass burning accounted for up to 20% of the baseline particle number concentration- and cloud condensation nuclei-weighted relative differences over the SPMA (2,300 and 1,400 cm−3, respectively). ©2018. American Geophysical Union. All Rights Reserved."
"56428816500;56784019900;57201822125;23013616900;7404770740;","Improvement of the Fmask algorithm for Sentinel-2 images: Separating clouds from bright surfaces based on parallax effects",2018,"10.1016/j.rse.2018.04.046","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046170750&doi=10.1016%2fj.rse.2018.04.046&partnerID=40&md5=703651db50146452081ba2c19a4eb9f7","Reliable identification of clouds is necessary for any type of optical remote sensing image analysis, especially in operational and fully automatic setups. One of the most elaborated and widespread algorithms, namely Fmask, was initially developed for the Landsat suite of satellites. Despite their similarity, application to Sentinel-2 imagery is currently hampered by the unavailability of a thermal band, and although results can be improved when taking the cirrus band into account, Sentinel-2 cloud detections are unsatisfactory in two points. (1) Low altitude clouds can be undetectable in the cirrus band, and (2) bright land surfaces – especially built-up structures – are often misclassified as clouds when only considering spectral information. In this paper, we present the Cloud Displacement Index (CDI), which makes use of the three highly correlated near infrared bands that are observed with different view angles. Hence, elevated objects like clouds are observed under a parallax and can be reliably separated from bright ground objects. We compare CDI with the currently used cloud probabilities, and propose how to integrate this new functionality into the Fmask algorithm. We validate the approach using test images over metropolitan areas covering a wide variety of global environments and climates, indicating the successful separation of clouds and built-up structures (overall accuracy 95%, i.e. an improvement in overall accuracy of 0.29–0.39 compared to the previous Fmask versions over the 20 test sites), and hence a full compensation for a missing thermal band. © 2018 The Authors"
"7005527701;7402396019;","Supersaturation on Pluto and elsewhere",2018,"10.1016/j.icarus.2018.04.025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046745002&doi=10.1016%2fj.icarus.2018.04.025&partnerID=40&md5=4f5730d5dc89eff465336ed93ae099f7","The atmosphere of Pluto contains a global thin haze layer, possibly clouds and a variety of gaseous species which may be supersaturated under some conditions. Studies of Pluto climate necessitate a fairly good knowledge of the interactions between gases and aerosols since it has an impact on the vertical profiles of these species and on the fluxes of matter at the planetary scale. In this paper we use the laws of cloud nucleation to evaluate the supersaturation which is needed to trigger condensation. HCN and H2O can supersaturate by factor from several thousand to several billions depending on the type of nucleation which is used. Other species can supersaturate, but with smaller values of saturation. Gaseous species also found as ices at the surface (e.g., CO, N2, CH4) are of special interest. At a surface temperature of 37 K, they can be supersaturated with S between 1.5 to 2 even if condensation nuclei are available in large number. Such supersaturation factors have an impact on fluxes of these species from the surface to the atmosphere. © 2018 Elsevier Inc."
"56518508500;7401958053;7402146514;36634248500;37056513600;14071389300;57199903513;","Developing a composite daily snow cover extent record over the Tibetan Plateau from 1981 to 2016 using multisource data",2018,"10.1016/j.rse.2018.06.021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048827964&doi=10.1016%2fj.rse.2018.06.021&partnerID=40&md5=fef2b0e3b2268a991e4e829525a315a1","Snow cover condition across the Tibetan Plateau (TP) is not only a significant indicator of climate change but also a vital variable in water availability because of its water storage function in high-mountain regions of Southwest China and the surrounding Asian countries. Limited by low spatial resolution, incomplete spatial coverage, and short time span of the current snow cover products, the long-term snow cover change across the TP under the climate change background remains unclear. To resolve this issue, a composite long-term gap-filled TP daily 5-km snow cover extent (SCE) record (TPSCE) is generated by integrating SCE from the Advanced Very High-Resolution Radiometer (AVHRR) surface reflectance climate data record (CDR) and several existing snow cover data sets, with the help of a decision tree snow cover mapping algorithm, for the period 1981–2016. A snow discrimination process was used to classify the land surface into snow (pre-TPSCE) and non-snow using AVHRR surface reflectance CDR. To fill gaps caused by invalid observations and cloud contamination in pre-TPSCE, several existing daily SCE products, including MOD10C1, MYD10C1, IMS, JASMES, and a passive microwave snow depth data set are employed in the composition process. The daily snow discrimination accuracy, tested by ground snow-depth observations during 2000–2014, shows that the TPSCE captures the distribution of snow duration days (R2 = 0.80, bias = 3.93 days) effectively. The comparison between the TPSCE and fine-resolution snow cover maps (MCD10A1-TP) indicates high comparability between the TPSCE and MCD10A1-TP. In addition, cross-comparisons with changes in temperature, precipitation, and land surface albedo indicate that the TPSCE is reliable in climate change studies. In summary, the TPSCE is spatially complete and covers the longest period among all current snow cover products from satellite observations. The TPSCE seamlessly records changes in snow cover across the TP over the past 36 years, thereby providing valuable snow information for climate change and hydrological studies. © 2018 Elsevier Inc."
"55623496800;7405266599;57207831468;57190309014;55660852700;","Annual forest aboveground biomass changes mapped using ICESat/GLAS measurements, historical inventory data, and time-series optical and radar imagery for Guangdong province, China",2018,"10.1016/j.agrformet.2018.04.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046336365&doi=10.1016%2fj.agrformet.2018.04.005&partnerID=40&md5=881d3b10917dabfd642d6c5438a32e95","Forest aboveground biomass (AGB) assessments are essential for accurate understanding of carbon accounting under forest disturbance effects and climate change. We mapped AGB data (from 1986 to 2016) by combining the forest inventories and multisource remotely sensed data, including the Ice, Cloud, and Land Elevation Satellite data and Landsat dense time series imagery, and L-band Synthetic Aperture Radar (PALSAR) mosaic data in Guangdong, China. We used random forest (RF) and stochastic gradient boosting (SGB) algorithms to determine the optimal variables of statistical models for mapping and validation of the AGB purpose. Our results showed that the Geoscience Laser Altimeter System (GLAS)-based AGB correlated well (R2 adj = 0.89, n = 277, p < 0.001, RMSE = 21.24t/ha) with those obtained using the field-based method that used an RF-based approach, although inevitably, there is a saturation problem. The combined remotely sensed optical and radar imagery and ancillary data sets for mapping AGB using the RF algorithm yielded a stronger (R2 adj = 0.86, n = 558, p < 0.001, RMSE = 11.35t/ha) linear correlation with those produced using the GLAS waveform data than that produced using the SGB algorithm. The overall accuracy and Kappa coefficient of mapping forests based on the PALSAR-forest/non-forest Landsat-based phenology for AGB masking were approximately 92.1% and 0.83, respectively. Additionally, the total amount of AGB had increased from 1986 to 2016 by 55.9%. The same increasing trend was observed for total AGB in both mid-subtropical (from 42% to 62%) and south-subtropical (from 38% to 57%) evergreen broadleaved forests, whereas a decreasing trend was witnessed in the tropical forest, particularly after 2010. There was an upward trend of total AGB among the four economic zones of Guangdong; the mountainous area had the highest AGB value distribution, accounting for 58%–70%, followed by the Pearl River Delta region (20%–30%), the western coast of Guangdong (3%–9%), and the eastern coast of Guangdong (2%–7%). The resulting provincial continuous forest AGB maps will provide a better evaluation of carbon dynamic in southern China. © 2018 Elsevier B.V."
"24528897900;23486734100;57208462871;56244473600;7103206141;","Changes in the aerosol direct radiative forcing from 2001 to 2015: Observational constraints and regional mechanisms",2018,"10.5194/acp-18-13265-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053438786&doi=10.5194%2facp-18-13265-2018&partnerID=40&md5=283d2c6f0c76ccc04a38c55a1d17397e","We present estimates of changes in the direct aerosol effects (DRE) and its anthropogenic component (DRF) from 2001 to 2015 using the GFDL chemistry-climate model AM3 driven by CMIP6 historical emissions. AM3 is evaluated against observed changes in the clear-sky shortwave direct aerosol effect (DREswclr) derived from the Clouds and the Earth's Radiant Energy System (CERES) over polluted regions. From 2001 to 2015, observations suggest that DREclrsw increases (i.e., less radiation is scattered to space by aerosols) over western Europe (0.7-1Wm'2decade'1) and the eastern US (0.9-1.4Wm'2decade'1), decreases over India ('1 to'1.6Wm'2decade'1), and does not change significantly over eastern China. AM3 captures these observed regional changes in DREclrsw well in the US and western Europe, where they are dominated by the decline of sulfate aerosols, but not in Asia, where the model overestimates the decrease of DREclrsw. Over India, the model bias can be partly attributed to a decrease of the dust optical depth, which is not captured by our model and offsets some of the increase of anthropogenic aerosols. Over China, we find that the decline of SO2 emissions after 2007 is not represented in the CMIP6 emission inventory. Accounting for this decline, using the Modular Emission Inventory for China, and for the heterogeneous oxidation of SO2 significantly reduces the model bias. For both India and China, our simulations indicate that nitrate and black carbon contribute more to changes in DREclrsw than in the US and Europe. Indeed, our model suggests that black carbon (+0.12Wm'2) dominates the relatively weak change in DRF from 2001 to 2015 (+0.03Wm'2). Over this period, the changes in the forcing from nitrate and sulfate are both small and of the same magnitude ('0.03Wm'2 each). This is in sharp contrast to the forcing from 1850 to 2001 in which forcings by sulfate and black carbon largely cancel each other out, with minor contributions from nitrate. The differences between these time periods can be well understood from changes in emissions alone for black carbon but not for nitrate and sulfate; this reflects non-linear changes in the photochemical production of nitrate and sulfate associated with changes in both the magnitude and spatial distribution of anthropogenic emissions. © Author(s) 2018."
"35096299800;7006705919;55688930000;7004299063;56940125000;57203200427;8397494800;7102805852;37037519900;7407104838;23095179000;57207008570;53878006900;6506373162;36097570900;7404732357;9249627300;7408519438;55317177900;","The climate effects of increasing ocean albedo: An idealized representation of solar geoengineering",2018,"10.5194/acp-18-13097-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053256584&doi=10.5194%2facp-18-13097-2018&partnerID=40&md5=87eece480581fe7b9f6d2e324225a6c6","Geoengineering, or climate intervention, describes methods of deliberately altering the climate system to offset anthropogenic climate change. As an idealized representation of near-surface solar geoengineering over the ocean, such as marine cloud brightening, this paper discusses experiment G1ocean-albedo of the Geoengineering Model Intercomparison Project (GeoMIP), involving an abrupt quadrupling of the CO2 concentration and an instantaneous increase in ocean albedo to maintain approximate net top-of-atmosphere radiative flux balance. A total of 11 Earth system models are relatively consistent in their temperature, radiative flux, and hydrological cycle responses to this experiment. Due to the imposed forcing, air over the land surface warms by a model average of 1.14 K, while air over most of the ocean cools. Some parts of the near-surface air temperature over ocean warm due to heat transport from land to ocean. These changes generally resolve within a few years, indicating that changes in ocean heat content play at most a small role in the warming over the oceans. The hydrological cycle response is a general slowing down, with high heterogeneity in the response, particularly in the tropics. While idealized, these results have important implications for marine cloud brightening, or other methods of geoengineering involving spatially heterogeneous forcing, or other general forcings with a strong land-ocean contrast. It also reinforces previous findings that keeping top-of-atmosphere net radiative flux constant is not sufficient for preventing changes in global mean temperature. © Author(s) 2018."
"56571063800;55923546200;56377286600;8942524900;43661479500;7103373205;57201820235;8633783900;7004469744;","The importance of comprehensive parameter sampling and multiple observations for robust constraint of aerosol radiative forcing",2018,"10.5194/acp-18-13031-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053206091&doi=10.5194%2facp-18-13031-2018&partnerID=40&md5=d4765eebe5155d9ad9265a4cb752c4c6","Observational constraint of simulated aerosol and cloud properties is an essential part of building trustworthy climate models for calculating aerosol radiative forcing. Models are usually tuned to achieve good agreement with observations, but tuning produces just one of many potential variants of a model, so the model uncertainty cannot be determined. Here we estimate the uncertainty in aerosol effective radiative forcing (ERF) in a tuned climate model by constraining 4 million variants of the HadGEM3-UKCA aerosol-climate model to match nine common observations (top-of-atmosphere shortwave flux, aerosol optical depth, PM2.5, cloud condensation nuclei at 0.2% supersaturation (CCN0.2), and concentrations of sulfate, black carbon and organic carbon, as well as decadal trends in aerosol optical depth and surface shortwave radiation.) The model uncertainty is calculated by using a perturbed parameter ensemble that samples 27 uncertainties in both the aerosol model and the physical climate model, and we use synthetic observations generated from the model itself to determine the potential of each observational type to constrain this uncertainty. Focusing over Europe in July, we show that the aerosol ERF uncertainty can be reduced by about 30% by constraining it to the nine observations, demonstrating that producing climate models with an observationally plausible base state can contribute to narrowing the uncertainty in aerosol ERF. However, the uncertainty in the aerosol ERF after observational constraint is large compared to the typical spread of a multi-model ensemble. Our results therefore raise questions about whether the underlying multi-model uncertainty would be larger if similar approaches as adopted here were applied more widely. The approach presented in this study could be used to identify the most effective observations for model constraint. It is hoped that aerosol ERF uncertainty can be further reduced by introducing process-related constraints; however, any such results will be robust only if the enormous number of potential model variants is explored. © 2018 Author(s)."
"57203801897;7409080503;8953662800;7403564495;8839875600;","The climate impact of aerosols on the lightning flash rate: Is it detectable from long-term measurements?",2018,"10.5194/acp-18-12797-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052990649&doi=10.5194%2facp-18-12797-2018&partnerID=40&md5=e5c11c58356836daf0db052b697707da","The effect of aerosols on lightning has been noted in many case studies, but much less is known about the long-term impact, relative importance of dynamics-thermodynamics versus aerosol, and any difference by different types of aerosols. Attempts are made to tackle all these factors, whose distinct roles are discovered by analyzing 11-year datasets of lightning, aerosol loading and composition, and dynamic-thermodynamic data from satellite and model reanalysis. Variations in the lightning rate are analyzed with respect to changes in dynamic-thermodynamic variables and indices such as the convective available potential energy (CAPE) and vertical wind shear. In general, lightning has strong diurnal and seasonal variations, peaking in the afternoon and during the summer. The lightning flash rate is much higher in moist central Africa than in dry northern Africa presumably because of the combined influences of surface heating, CAPE, relative humidity (RH), and aerosol type. In both regions, the lightning flash rate changes with aerosol optical depth (AOD) in a boomerang shape: first increasing with AOD, tailing off around AOD = 0.3, and then behaving differently, i.e., decreasing for dust and flattening for smoke aerosols. The deviation is arguably caused by the tangled influences of different thermodynamics (in particular humidity and CAPE) and aerosol type between the two regions. In northern Africa, the two branches of the opposite trends seem to echo the different dominant influences of the aerosol microphysical effect and the aerosol radiative effect that are more pronounced under low and high aerosol loading conditions, respectively. Under low-AOD conditions, the aerosol microphysical effect more likely invigorates deep convection. This may gradually yield to the suppression effect as AOD increases, leading to more and smaller cloud droplets that are highly susceptible to evaporation under the dry conditions of northern Africa. For smoke aerosols in moist central Africa, the aerosol invigoration effect can be sustained across the entire range of AOD by the high humidity and CAPE. This, plus a potential heating effect of the smoke layer, jointly offsets the suppression of convection due to the radiative cooling at the surface by smoke aerosols. Various analyses were done that tend to support this hypothesis. © Author(s) 2018."
"57193314579;57214536094;44861281500;8088667300;10244893900;57089899400;8791306500;6603533215;9238037100;","Evaluation of MUSICA IASI tropospheric water vapour profiles using theoretical error assessments and comparisons to GRUAN Vaisala RS92 measurements",2018,"10.5194/amt-11-4981-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053154756&doi=10.5194%2famt-11-4981-2018&partnerID=40&md5=155e76c9b1cd4cdde61072662c6c4e6c","Volume mixing ratio water vapour profiles have been retrieved from IASI (Infrared Atmospheric Sounding Interferometer) spectra using the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) processor. The retrievals are done for IASI observations that coincide with Vaisala RS92 radiosonde measurements performed in the framework of the GCOS (Global Climate Observing System) Reference Upper-Air Network (GRUAN) in three different climate zones: the tropics (Manus Island, 2°S), mid-latitudes (Lindenberg, 52°N), and polar regions (Sodankylä, 67°N). The retrievals show good sensitivity with respect to the vertical H2O distribution between 1km above ground and the upper troposphere. Typical DOFS (degrees of freedom for signal) values are about 5.6 for the tropics, 5.1 for summertime mid-latitudes, 3.8 for wintertime mid-latitudes, and 4.4 for summertime polar regions. The errors of the MUSICA IASI water vapour profiles have been theoretically estimated considering the contribution of many different uncertainty sources. For all three climate regions, unrecognized cirrus clouds and uncertainties in atmospheric temperature have been identified as the most important error sources and they can reach about 25%. The MUSICA IASI water vapour profiles have been compared to 100 individual coincident GRUAN water vapour profiles. The systematic difference between the data is within 11% below 12km altitude; however, at higher altitudes the MUSICA IASI data show a dry bias with respect to the GRUAN data of up to 21%. The scatter is largest close to the surface (30%), but never exceeds 21% above 1km altitude. The comparison study documents that the MUSICA IASI retrieval processor provides H2O profiles that capture the large variations in H2O volume mixing ratio profiles well from 1km above ground up to altitudes close to the tropopause. Above 5km the observed scatter with respect to GRUAN data is in reasonable agreement with the combined MUSICA IASI and GRUAN random errors. The increased scatter at lower altitudes might be explained by surface emissivity uncertainties at the summertime continental sites of Lindenberg and Sodankylä, and the upper tropospheric dry bias might suggest deficits in correctly modelling the spectroscopic line shapes of water vapour. © Author(s) 2018."
"57203167372;55540905400;54790508000;57203168832;57205299256;","Snow cover mapped daily at 30 meters resolution using a fusion of multi-temporal MODIS NDSI data and Landsat surface reflectance",2018,"10.1080/07038992.2018.1538775","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059480108&doi=10.1080%2f07038992.2018.1538775&partnerID=40&md5=727fcccb08abb0dde76513a5bd94bc72","Snow fall and melt events are complex meteorological phenomena that help chart the effects of climate change and impact many critical environmental processes including hydrologic and biogeographic systems. Daily snow maps, derived from MODIS imagery, provide managers and researchers with vital snow cover information, but only at spatial scales of 500 m or more. Finer resolution time series maps, however, retain large temporal gaps, particularly during recurrent cloud cover. This paper’s authors have developed the novel algorithm MODSAT-NDSI to harness the strengths of both coarse and finer spatial resolution imagery by fusing MODIS and Landsat normalized difference snow index (NDSI) data. Daily 30 m snow cover maps were thus generated for 2000–2017 with an overall accuracy of 90%, using 33 validation sites distributed throughout south-central British Columbia. Snow cover trends were analyzed across stratified elevation bands and land cover types, revealing that snow cover persists under lower elevation forests for an average of 23.5 d longer than in adjacent open areas during spring. We conclude that the MODSAT-NDSI approach captures temporal and spatial advantages of freely available snow cover datasets and can be modified to suit a variety of novel investigations relating to snow cover or other spectral indices. © 2018, Copyright © CASI."
"55823659900;7403076014;","A test of emergent constraints on cloud feedback and climate sensitivity using a calibrated single-model ensemble",2018,"10.1175/JCLI-D-17-0682.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052973920&doi=10.1175%2fJCLI-D-17-0682.1&partnerID=40&md5=ecda73d3deeeda317595a1e570d1e4da","A calibrated single-model ensemble (SME) derived from the NCAR Community Atmosphere Model, version 3.1, is used to test two hypothesized emergent constraints on cloud feedback and equilibrium climate sensitivity (ECS). The Fasullo and Trenberth relative humidity (RH) metric and the Sherwood et al. lowertropospheric mixing (LTMI) metric are computed for the present-day climate of the SME, and the relationships between the metrics, ECS, and cloud and other climate feedbacks are examined. The tropical convergence zone relative humidity (RHM) and the parameterized lower-tropospheric mixing (LTMIS) are positively correlated to ECS, and each is associated with a different spatial pattern of tropical shortwave cloud feedback in the SME. However, neither of those metrics is linked to the type of cloud response hypothesized by its authors. The resolved lower-tropospheric mixing (LTMID) is positively correlated to ECS for a subset of the SME having LTMID over a threshold value. LTMI and the RH for the dry, descending branch of the Hadley cell (RHD) narrow and shift upward the posterior estimates of ECS in the SME, but the SME bias in RHD and concerns over poorly understood physical mechanisms suggest the narrowing could be spurious for both constraints. While calibrated SME results may not generalize to multimodel ensembles, they can enhance the process understanding of emergent constraints and serve as out-of-sample tests of robustness. © 2018 American Meteorological Society."
"57200547267;25823927100;","Alleviated Double ITCZ Problem in the NCAR CESM1: A New Cloud Scheme and the Working Mechanisms",2018,"10.1029/2018MS001343","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053659268&doi=10.1029%2f2018MS001343&partnerID=40&md5=fbb2c66ac0c782e5782eda4273355ff1","Simulation of tropical precipitation in global climate models remains a challenge, in which double Intertropical Convergence Zone (ITCZ) bias is a prominent manifest. Compared with the original cloud scheme, a new diagnostic statistical cloud macrophysics scheme alleviates the spurious southern ITCZ bias associated with warm sea surface temperature (SST) bias over the central Pacific in the National Center for Atmospheric Research (NCAR) Community Earth System Model, version 1 (CESM1). Owing to the reduced net surface shortwave radiation associated with the increased low cloud fraction and liquid water path over the southeastern Pacific Ocean, the new scheme reduced local SST and further suppressed convection and precipitation. Stronger Walker circulation and enhanced tropical easterlies lead to increased tropical ocean zonal currents, which further lead to reduced SST in the central Pacific due to increased oceanic cold advection. As a result, over the central Pacific, SST cooling suppresses precipitation and alleviates the double ITCZ bias. The study suggests that low clouds over subtropical eastern ocean regions can impact tropical circulation and precipitation via a strong coupling with SST and ocean dynamics. ©2018. The Authors."
"55894937000;7004544454;55796430300;","Importance of positive cloud feedback for tropical Atlantic interhemispheric climate variability",2018,"10.1007/s00382-017-3978-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032375069&doi=10.1007%2fs00382-017-3978-1&partnerID=40&md5=f7319741f81e50849ef2fe89053df037","Over the tropical Atlantic during boreal spring, average interhemispheric differences in sea-surface temperature (SST) coincide with a coherent pattern of interannual climate variability often referred to as the Atlantic Meridional Mode. This includes anomalous SST and sea-level pressure roughly anti-symmetric about the equator, as well as cross-equatorial near-surface winds directed toward the warmer hemisphere. Within subtropical marine boundary layer cloud regions in both hemispheres, enhanced cloudiness associated with this variability is co-located with cool SST, a strong temperature inversion, and cold horizontal surface temperature advection, while reduced cloudiness is associated with the opposite meteorological conditions. This is indicative a positive cloud feedback that reinforces the underlying SST anomalies. The simulation of this feedback varies widely among models participating in phase 5 of the Coupled Model Intercomparison Project. Models that fail to simulate this feedback substantially underestimate the amplitudes of typical tropical Atlantic interhemispheric variability in cloudiness off of the equator, SST, and atmospheric circulation. Models that correctly reproduce a positive cloud feedback generally produce higher and more realistic amplitudes of variability, but with substantial scatter. Marine boundary layer clouds therefore appear to be a key element of springtime coupled atmosphere–ocean variability over the tropical Atlantic. A markedly more successful simulation of this variability in climate models may be obtained by better representing boundary layer cloud processes. © 2017, Springer-Verlag GmbH Germany."
"57191343618;56250119900;23479549200;","An energy balance model exploration of the impacts of interactions between surface albedo, cloud cover and water vapor on polar amplification",2018,"10.1007/s00382-017-3974-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033463505&doi=10.1007%2fs00382-017-3974-5&partnerID=40&md5=5bd7bbf29657f8a5049e67184b723469","We examine the effects of non-linear interactions between surface albedo, water vapor and cloud cover (referred to as climate variables) on amplified warming of the polar regions, using a new energy balance model. Our simulations show that the sum of the contributions to surface temperature changes due to any variable considered in isolation is smaller than the temperature changes from coupled feedback simulations. This non-linearity is strongest when all three climate variables are allowed to interact. Surface albedo appears to be the strongest driver of this non-linear behavior, followed by water vapor and clouds. This is because increases in longwave radiation absorbed by the surface, related to increases in water vapor and clouds, and increases in surface absorbed shortwave radiation caused by a decrease in surface albedo, amplify each other. Furthermore, our results corroborate previous findings that while increases in cloud cover and water vapor, along with the greenhouse effect itself, warm the polar regions, water vapor also significantly warms equatorial regions, which reduces polar amplification. Changes in surface albedo drive large changes in absorption of incoming shortwave radiation, thereby enhancing surface warming. Unlike high latitudes, surface albedo change at low latitudes are more constrained. Interactions between surface albedo, water vapor and clouds drive larger increases in temperatures in the polar regions compared to low latitudes. This is in spite of the fact that, due to a forcing, cloud cover increases at high latitudes and decreases in low latitudes, and that water vapor significantly enhances warming at low latitudes. © 2017, Springer-Verlag GmbH Germany."
"57201828043;","On the Time Evolution of Climate Sensitivity and Future Warming",2018,"10.1029/2018EF000889","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053939580&doi=10.1029%2f2018EF000889&partnerID=40&md5=0c8820197d91ff1f854adda5885c50a1","The Earth's climate sensitivity to radiative forcing remains a key source of uncertainty in future warming projections. There is a growing realization in recent literature that research must go beyond an equilibrium and CO2-only viewpoint, toward considering how climate sensitivity will evolve over time in response to anthropogenic and natural radiative forcing from multiple sources. Here the transient behavior of climate sensitivity is explored using a modified energy balance model, in which multiple climate feedbacks evolve independently over time to multiple sources of radiative forcing, combined with constraints from observations and from the Climate Model Intercomparison Project phase 5 (CMIP5). First, a large initial ensemble of 107 simulations is generated, with a distribution of climate feedback strengths from subannual to 102-year timescales constrained by the CMIP5 ensemble, including the Planck feedback, the combined water vapor lapse rate feedback, snow and sea ice albedo feedback, fast cloud feedbacks, and the cloud response to sea surface temperature adjustment feedback. These 107 simulations are then tested against observational metrics representing decadal trends in warming, heat and carbon uptake, leaving only 4.6 × 103 history-matched simulations consistent with both the CMIP5 ensemble and historical observations. The results reveal an annual timescale climate sensitivity of 2.1 °C (ranging from 1.6 to 2.8 °C at 95% uncertainty), rising to 2.9 °C (from 1.9 to 4.6 °C) on century timescales. These findings provide a link between lower estimates of climate sensitivity, based on the current transient state of the climate system, and higher estimates based on long-term behavior of complex models and palaeoclimate evidence. ©2018. The Authors."
"56735366800;57200337035;55687238300;12762440500;56111060800;56954125400;56954072000;","Analyzing of cloud macroscopic characteristics in the Shigatse Area of the Tibetan Plateau using the total-sky images",2018,"10.1175/JAMC-D-18-0095.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053465748&doi=10.1175%2fJAMC-D-18-0095.1&partnerID=40&md5=5e6d964d2dc7b0ee03f4aa5aaedfff8a","The macroscopic characteristics of clouds in the Tibetan Plateau are crucial to understanding the local climatic conditions and their impact on the global climate and water vapor cycle. In this study, the variations of cloud cover and cloud types are analyzed by using total-sky images of two consecutive years in Shigatse, Tibetan Plateau. The results show that the cloud cover in Shigatse presents a distinct seasonal difference that is characterized by low cloud cover in autumn and winter and high cloud cover in summer and spring. July is the month with the largest cloud coverage, and its average cloud cover exceeds 75%. The probability of clouds in the sky is the lowest in November, with an average cloud cover of less than 20%. The diurnal variations of cloud cover in different months also have considerable differences. Specifically, cloud cover is higher in the afternoon than that in the morning in most months, whereas the cloud cover throughout the day varies little from July to September. The dominant cloud types in different months are also not the same. The proportion of clear sky is large in autumn and winter. Stratiform cloud occupies the highest percentage in March, April, July, and August. The probability of emergence of cirrus is highest in May and June. The Shigatse region has clear rainy and dry seasons, and correlation analysis between precipitation and clouds shows that the largest cumulative precipitation, the highest cloud cover, and the highest proportion of stratiform clouds occur simultaneously in July. © 2018 American Meteorological Society."
"26424657400;55578895400;35190076500;22950688100;6603432436;","Origin of the warm eastern tropical Atlantic SST bias in a climate model",2018,"10.1007/s00382-017-3984-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032797488&doi=10.1007%2fs00382-017-3984-3&partnerID=40&md5=3907ca32d5ae47383243335fe5236efd","The substantial warm sea surface temperature bias in the eastern Tropical Atlantic reported in most CMIP5 climate simulations with various models, in particular along the coast of Namibia and Angola, remains an issue in more recent and CMIP6-ready versions of climate models such as EC-Earth. A complete and original set of experiments with EC-Earth3.1 is performed to investigate the causes and mechanisms responsible for the emergence and persistence of this bias. The fully-developed bias is studied in a historical experiment that has reached quasi-equilibrium, while retrospective prediction experiments are used to highlight the development/growth from an observed initial state. Prediction experiments are performed at both low and high resolution to assess the possible dependence of the bias on horizontal resolution. Standalone experiments with the ocean and the atmosphere components of EC-Earth are also analyzed to separate the respective contributions of the ocean and atmosphere to the development of the bias. EC-Earth3.1 exhibits a bias similar to that reported in most climate models that took part in CMIP5. The magnitude of this bias, however, is weaker than most CMIP5 models by few degrees. Increased horizontal resolution only leads to a minor reduction of the bias in EC-Earth. The warm SST bias is found to be the result of an excessive solar absorption in the ocean mixed layer, which can be linked to the excessive solar insolation due to unrealistically low cloud cover, and the absence of spatial and temporal variability of the biological productivity in the ocean component. The warm SST bias is further linked to deficient turbulent vertical mixing of cold water to the mixed layer. Our study points at a need for better representation of clouds in the vicinity of eastern boundaries in atmosphere models, and better representation of solar penetration and turbulent mixing in the ocean models in order to eliminate the Tropical Atlantic biases. © 2017, Springer-Verlag GmbH Germany."
"55656523500;55738957800;","Understanding and improving the scale dependence of trigger functions for convective parameterization using cloud-resolving model data",2018,"10.1175/JCLI-D-17-0660.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052931157&doi=10.1175%2fJCLI-D-17-0660.1&partnerID=40&md5=441925d1a081fbb325581a6f25d7161d","As the resolution of global climate model increases, whether trigger functions in current convective parameterization schemes still work remains unknown. In this study, the scale dependence of undilute and dilute dCAPE, Bechtold, and heated condensation framework (HCF) triggers is evaluated using the cloud-resolving model (CRM) data. It is found that all these trigger functions are scale dependent, especially for dCAPE-type triggers, with skill scores dropping from ~0.6 at the lower resolutions (128, 64, and 32 km) to only ~0.1 at 4 km. The average convection frequency decreases from 14.1% at 128 km to 2.3% at 4 km in the CRM data, but it increases rapidly in the dCAPE-type triggers and is almost unchanged in the Bechtold and HCF triggers across resolutions, all leading to large overpredictions at higher resolutions. In the dCAPE-type triggers, the increased frequency is due to the increased rate of dCAPE greater than the threshold (65 J kg-1 h-1) at higher resolutions. The box-and-whisker plots show that the main body of dCAPE in the correct prediction and overprediction can be separated from each other in most resolutions. Moreover, the underprediction is found to be corresponding to the decaying phase of convection. Hence, two modifications are proposed to improve the scale dependence of the undilute dCAPE trigger: 1) increasing the dCAPE threshold and 2) considering convection history, which checks whether there is convection prior to the current time. With these modifications, the skill at 16 km, 8 km, and 4 km can be increased from 0.50, 0.27, and 0.15 to 0.70, 0.61, and 0.53, respectively. © 2018 American Meteorological Society."
"57203728479;7401526171;7005052907;","Bias adjustment of satellite-based precipitation estimation using artificial neural networks-cloud classification system over Saudi Arabia",2018,"10.1007/s12517-018-3860-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052732356&doi=10.1007%2fs12517-018-3860-4&partnerID=40&md5=b10e02a29a6ee16cd2ae3615d7dc44fa","Precipitation is a key input variable for hydrological and climate studies. Rain gauges can provide reliable precipitation measurements at a point of observations. However, the uncertainty of rain measurements increases when a rain gauge network is sparse. Satellite-based precipitation estimations SPEs appear to be an alternative source of measurements for regions with limited rain gauges. However, the systematic bias from satellite precipitation estimation should be estimated and adjusted. In this study, a method of removing the bias from the precipitation estimation from remotely sensed information using artificial neural networks-cloud classification system (PERSIANN-CCS) over a region where the rain gauge is sparse is investigated. The method consists of monthly empirical quantile mapping of gauge and satellite measurements over several climate zones as well as inverse-weighted distance for the interpolation of gauge measurements. Seven years (2010–2016) of daily precipitation estimation from PERSIANN-CCS was used to test and adjust the bias of estimation over Saudi Arabia. The first 6 years (2010–2015) are used for calibration, while 1 year (2016) is used for validation. The results show that the mean yearly bias is reduced by 90%, and the yearly root mean square error is reduced by 68% during the validation year. The experimental results confirm that the proposed method can effectively adjust the bias of satellite-based precipitation estimations. © 2018, Saudi Society for Geosciences."
"35325977100;7005461477;","Convective variability associated with the boreal summer intraseasonal oscillation in the South China sea region",2018,"10.1175/JCLI-D-18-0091.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052958316&doi=10.1175%2fJCLI-D-18-0091.1&partnerID=40&md5=8bcda760fb57faf06e3bc1835ec17146","This study investigates the convective cloud population, precipitation microphysics, and lightning activity associated with the boreal summer intraseasonal oscillation (BSISO) over the South China Sea (SCS) and surrounding landmasses. SCS rainfall shows a marked 30-60-day intraseasonal variability. This variability is less evident over land. The population of mesoscale convective systems (MCSs) and the stratiform rain fraction over the SCS, Philippines, and Indochina increase remarkably after the onset of BSISO. Convection over the SCS during inactive periods exhibits a trimodal population including shallow cumulus, congestus, and deep convection, mirroring the situation over tropical open oceans. The shallow mode is absent over land. Shallow cumulus clouds rapidly transition to congestus clouds over the SCS under active BSISO conditions. Over land, deep convection and lightning lead total rainfall and MCSs by 2-3 BSISO phases, whereas they are somewhat in phase over the SCS. Although convective instability over the SCS is larger during active periods compared to inactive periods, variability in convective intensity and precipitation microphysics is minimal, with active periods showing only higher frequency of moderate ice scattering and 30-dBZ heights extending to 210°C. Over the Philippines and Indochina, inactive phases exhibit substantially stronger ice scattering signatures, robust mixed-phase microphysics, and higher lightning flash rates, possibly due to greater convective instability and a stronger convective diurnal cycle. Total rainfall, convective environments, and convective structures over Borneo are all out of phase with that over the Philippines and Indochina, while southern China shows little BSISO variability on convective intensity and lightning frequency. © 2018 American Meteorological Society."
"22953153500;22940182000;57193879862;54386489200;15755995900;7006705919;55802246600;","Characterizing the Relative Importance Assigned to Physical Variables by Climate Scientists when Assessing Atmospheric Climate Model Fidelity",2018,"10.1007/s00376-018-7300-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049557012&doi=10.1007%2fs00376-018-7300-x&partnerID=40&md5=c2c26f49519e58f0e13eb33c355e24e1","Evaluating a climate model’s fidelity (ability to simulate observed climate) is a critical step in establishing confidence in the model’s suitability for future climate projections, and in tuning climate model parameters. Model developers use their judgement in determining which trade-offs between different aspects of model fidelity are acceptable. However, little is known about the degree of consensus in these evaluations, and whether experts use the same criteria when different scientific objectives are defined. Here, we report on results from a broad community survey studying expert assessments of the relative importance of different output variables when evaluating a global atmospheric model’s mean climate. We find that experts adjust their ratings of variable importance in response to the scientific objective, for instance, scientists rate surface wind stress as significantly more important for Southern Ocean climate than for the water cycle in the Asian watershed. There is greater consensus on the importance of certain variables (e.g., shortwave cloud forcing) than others (e.g., aerosol optical depth). We find few differences in expert consensus between respondents with greater or less climate modeling experience, and no statistically significant differences between the responses of climate model developers and users. The concise variable lists and community ratings reported here provide baseline descriptive data on current expert understanding of certain aspects of model evaluation, and can serve as a starting point for further investigation, as well as developing more sophisticated evaluation and scoring criteria with respect to specific scientific objectives. © 2018, The Authors."
"56193650100;56931957400;20436169300;20435752700;","Organization and Oscillations in Simulated Shallow Convective Clouds",2018,"10.1029/2018MS001416","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053670328&doi=10.1029%2f2018MS001416&partnerID=40&md5=a50668fd6c7e9e051eae88171fdd6454","Physical insights into processes governing temporal organization and evolution of cloud fields are of great importance for climate research. Here using large eddy simulations with a bin microphysics scheme, we show that warm convective cloud fields exhibit oscillations with two distinct periods (~10 and ~90 min, for the case studied here). The shorter period dominates the nonprecipitating phase, and the longer period is related to the precipitating phase. We show that rain processes affect the domain's thermodynamics, hence forcing the field into a low-frequency recharge-discharge cycle of developing cloudiness followed by precipitation-driven depletion. The end result of precipitation is stabilization of the lower atmosphere by warming of the cloudy layer (due to latent heat release) and cooling of the subcloud layer (by rain evaporation, creating cold pools). As the thermodynamic instability weakens, so does the cloudiness, and the rain ceases. During the nonprecipitating phase of the cycle, surface fluxes destabilize the boundary layer until the next precipitation cycle. Under conditions that do not allow development of precipitation (e.g., high aerosol loading), high-frequency oscillations dominate the cloud field. Clouds penetrating the stable inversion layer trigger gravity waves with a typical period of ~10 min. In return, the gravity waves modulate the clouds in the field by modifying the vertical velocity, temperature, and humidity fields. Subsequently, as the polluted nonprecipitating simulations evolve, the thermodynamic instability increases and the cloudy layer deepens until precipitation forms, shifting the oscillations from high to low frequency. The organization of cold pools and the spatial scale related to these oscillations are explored. ©2018. The Authors."
"7005063241;57193132723;9242539000;6603552777;9242540400;57191693467;","Climates of Warm Earth-like Planets. I. 3D Model Simulations",2018,"10.3847/1538-4365/aae9e1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059155569&doi=10.3847%2f1538-4365%2faae9e1&partnerID=40&md5=bd68b96cf1cba0b96b79f0dfafefa6bc","We present a large ensemble of simulations of an Earth-like world with increasing insolation and rotation rate. Unlike previous work utilizing idealized aquaplanet configurations, we focus our simulations on modern Earth-like topography. The orbital period is the same as that of modern Earth, but with zero obliquity and eccentricity. The atmosphere is 1 bar N2-dominated with CO2 = 400 ppmv and CH4 = 1 ppmv. The simulations include two types of oceans: one without ocean heat transport (OHT) between grid cells, as has been commonly used in the exoplanet literature, and the other a fully coupled dynamic bathtub type ocean. The dynamical regime transitions that occur as day length increases induce climate feedbacks producing cooler temperatures, first via the reduction of water vapor with increasing rotation period despite decreasing shortwave cooling by clouds, and then via decreasing water vapor and increasing shortwave cloud cooling, except at the highest insolations. Simulations without OHT are more sensitive to insolation changes for fast rotations, while slower rotations are relatively insensitive to ocean choice. OHT runs with faster rotations tend to be similar with gyres transporting heat poleward, making them warmer than those without OHT. For slower rotations OHT is directed equatorward and no high-latitude gyres are apparent. Uncertainties in cloud parameterization preclude a precise determination of habitability but do not affect robust aspects of exoplanet climate sensitivity. This is the first paper in a series that will investigate aspects of habitability in the simulations presented herein. The data sets from this study are open source and publicly available. © 2018. The American Astronomical Society. All rights reserved."
"57204731477;57204725804;","Method of Access Control Model Establishment for Marine Information Cloud Platforms Based on Docker Virtualization Technology",2018,"10.2112/SI82-013.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056903642&doi=10.2112%2fSI82-013.1&partnerID=40&md5=883616097472b7ae976ce08b5ccf1496","Shu, J. and Wu, Y., 2018. Method of access control model establishment for marine information cloud platforms based on Docker virtualization technology. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia. Aiming at the problem that the current access control model is inefficient and computationally intensive for marine information access control in cloud platforms, a method of access control model establishment of marine information cloud platforms based on Docker is proposed. Information entropy theory is used to implement the violation operation, and the security theorem of the access control model is given in the form of security entropy. Docker container virtualization technology and an attribute-based ciphertext access control scheme are used to jointly control the user cross-domain and cross-level access, and ensure consistency in the control of illegal access to realize establishment of the marine information cloud platform access control model. The experimental results showed that the proposed method can improve the control efficiency while ensuring the security of access. © Coastal Education and Research Foundation, Inc. 2018."
"57202688845;56268184900;24463072700;","Evaluating a fit-for-purpose integrated service-oriented land and climate change information system for mountain community adaptation",2018,"10.3390/ijgi7090343","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053688923&doi=10.3390%2fijgi7090343&partnerID=40&md5=ccbd7604489567843021580e3d1b6dc3","Climate change challenges mountain communities to prepare themselves via Community-Based Adaptation (CBA) plans that reduce vulnerability. This paper outlines the evaluation of a developed web-based information system to support CBA, referred to as a Mountain Community Adaptive System (MCAS). The web-based user interface visualizes collated data from data providers, integrating it with near real-time climate and weather datasets. The interface provides more up-to-date information than was previously available on the environment, particularly on land and climate. MCAS, a cloud-based Land Information System (LIS), was developed using an Agile-inspired approach offering system creation based on bare minimum system requirements and iterative development. The system was tested against Fit-For-Purpose Land Administration (FFP LA) criteria to assess the effectiveness in a case from Nepal. The results illustrate that an MCAS-style system can provide useful information such as land use status, adaptation options, near real-time rainfall and temperature details, amongst others, to enable services that can enhance CBA activities. The information can facilitate improved CBA planning and implementation at the mountain community level. Despite the mentioned benefits of MCAS, ensuring system access was identified as a key limitation: smartphones and mobile technologies still remain prohibitively expensive for members of mountain communities, and underlying information communication technology (ICT) infrastructures remain under-developed in the assessed mountain communities. The results of the evaluation further suggest that the land-related aspects of climate change should be added to CBA initiatives. Similarly, existing LIS could have functionalities extended to include climate-related variables that impact on land use, tenure, and development. © 2018 by the authors."
"7004364155;35206636900;7401776640;13204619900;8891521600;","Changes in Earth's energy budget during and after the ""Pause"" in global warming: An observational perspective",2018,"10.3390/cli6030062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053767692&doi=10.3390%2fcli6030062&partnerID=40&md5=8e3570d73a27749edfbbc2e072a55acc","This study examines changes in Earth's energy budget during and after the global warming ""pause"" (or ""hiatus"") using observations from the Clouds and the Earth's Radiant Energy System. We find a marked 0.83 ± 0.41 Wm-2 reduction in global mean reflected shortwave (SW) top-of-atmosphere (TOA) flux during the three years following the hiatus that results in an increase in net energy into the climate system. A partial radiative perturbation analysis reveals that decreases in low cloud cover are the primary driver of the decrease in SW TOA flux. The regional distribution of the SW TOA flux changes associated with the decreases in low cloud cover closely matches that of sea-surface temperature warming, which shows a pattern typical of the positive phase of the Pacific Decadal Oscillation. Large reductions in clear-sky SW TOA flux are also found over much of the Pacific and Atlantic Oceans in the northern hemisphere. These are associated with a reduction in aerosol optical depth consistent with stricter pollution controls in China and North America. A simple energy budget framework is used to show that TOA radiation (particularly in the SW) likely played a dominant role in driving the marked increase in temperature tendency during the post-hiatus period. © 2018 by the authors."
"57204734564;57204720074;57204725700;","Sensitive Data Leakage Prevention for Ship Communications under Cloud Computing Platforms",2018,"10.2112/SI82-024.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056901283&doi=10.2112%2fSI82-024.1&partnerID=40&md5=24051e39c01d268ad555f5252e2163c9","Liu, F.; Gao, X., and Wu, Y., 2018. Sensitive data leakage prevention for ship communications under cloud computing platforms. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia. Aimed at the problems of low data concealment rate and slow encryption speed in the current sensitive data leakage prevention method for ship communications, a new leakage prevention method under a cloud computing platform is put forward. First, the ship communication network was treated with k anonymization, and the sensitive data loss of the ship communication node cluster was calculated. Second, the sensitive data loss of anonymization in the whole-ship communication network was obtained by accumulating the sensitive data loss of the anonymous cluster of ship communication nodes, and then the loss rate of the sensitive data of ship communications was calculated. Finally, the elliptic encryption mechanism was adopted to achieve the encryption. It was found that with this method, the average concealment rate of sensitive data of ship communications is about 80%, and the average speed of sensitive data encryption for ship communications is up to 33 MB/s. The experiment proves that with good concealment performance, this method can prevent sensitive data leakage and improve the concealment rate and encryption speed. © Coastal Education and Research Foundation, Inc. 2018."
"56647601700;21743348300;7402270526;23011853200;56421781300;55949844200;","Validation of aerosol products from AATSR and MERIS/AATSR synergy algorithms-Part 1: Global evaluation",2018,"10.3390/rs10091414","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053622767&doi=10.3390%2frs10091414&partnerID=40&md5=d8d88b7a69f014d539c60ae4947160a7","The European Space Agency's (ESA's) Aerosol Climate Change Initiative (CCI) project intends to exploit the robust, long-term, global aerosol optical thickness (AOT) dataset from Europe's satellite observations. Newly released Swansea University (SU) aerosol products include AATSR retrieval and synergy between AATSR and MERIS with a spatial resolution of 10 km. In this study, both AATSR retrieval (SU/AATSR) and AATSR/MERIS synergy retrieval (SU/synergy) products are validated globally using Aerosol Robotic Network (AERONET) observations for March, June, September, and December 2008, as suggested by the Aerosol-CCI project. The analysis includes the impacts of cloud screening, surface parameterization, and aerosol type selections for two products under different surface and atmospheric conditions. The comparison between SU/AATSR and SU/synergy shows very accurate and consistent global patterns. The global evaluation using AERONET shows that the SU/AATSR product exhibits slightly better agreement with AERONET than the SU/synergy product. SU/synergy retrieval overestimates AOT for all surface and aerosol conditions. SU/AATSR data is much more stable and has better quality; it slightly underestimates fine-mode dominated and absorbing AOTs yet slightly overestimates coarse-mode dominated and non-absorbing AOTs. © 2018 by the authors."
"56119479900;55738957800;55577875600;","Linking stochasticity of convection to large-scale vertical velocity to improve Indian Summer Monsoon simulation in the NCAR CAM5",2018,"10.1175/JCLI-D-17-0785.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052806222&doi=10.1175%2fJCLI-D-17-0785.1&partnerID=40&md5=0646ecada08192d114aa590501db86c2","The Plant-Craig (PC) stochastic convective parameterization scheme is modified by linking the stochastic generation of convective clouds to the change of large-scale vertical pressure velocity at 500 hPa with time so as to better account for the relationship between convection and the large-scale environment. Three experiments using the National Center for Atmospheric Research (NCAR) Community Atmosphere Model, version 5 (CAM5), are conducted: one with the default Zhang-McFarlane deterministic convective scheme, another with the original PC stochastic scheme, and a third with the modified PC stochastic scheme. Evaluation is focused on the simulation of the Indian summer monsoon (ISM), which is a long-standing challenge for all current global circulation models. Results show that the modified stochastic scheme better represents the annual cycle of the climatological mean rainfall over central India and the mean onset date of ISM compared to other simulations. Also, for the simulations of ISM intraseasonal variability for quasi-biweekly and 30-60-day modes, the modified stochastic parameterization produces more realistic propagation and magnitude, especially for the observed northeastward movement of the 30-60-day mode, for which the other two simulations show the propagation in the opposite direction. Causes are investigated through a moisture budget analysis. Compared to the other two simulations, the modified stochastic scheme with an appropriate representation of convection better represents the patterns and amplitudes of large-scale dynamical convergence and moisture advection and thus corrects the monsoon cycle associated with their covariation during the peaks and troughs of intraseasonal oscillation. © 2018 American Meteorological Society."
"35186280000;36841957400;","Indian Ocean warming during peak El Niño cools surrounding land masses",2018,"10.1007/s00382-017-4001-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034229734&doi=10.1007%2fs00382-017-4001-6&partnerID=40&md5=2f4bc51e138dc1a939ffc0f5a4affa66","Understanding the interactions between the Pacific and other ocean basins during extreme phases of the El Niño-Southern Oscillation (ENSO) is necessary for explaining its global climate impacts. Here climate model experiments are used to highlight a mechanism by which the characteristic warming of the Indian Ocean during peak El Niño months can cool North Africa and South Asia, an area encompassing over three billion people. It is found that warming of the Indian Ocean during extreme El Niño events leads to broader upper tropospheric geopotential height anomalies than would otherwise occur. This weakens the extratropical Rossby wave response initiated in the tropics and leads to higher pressure and reduced cloud forcing over North Africa and South Asia. Reanalysis data provides empirical support for this mechanism, although it is likely only to be prominent during strong El Niño events when Indian Ocean warming tends to be larger. This dampening effect needs to be taken into account in understanding the climatic impact of extreme El Niño events, which are projected to increase under global warming. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature."
"36910224600;7006544303;57197766644;55694342800;55570003600;6505946652;57195445069;55443788900;6507237454;7202239288;","Assessing the effectiveness of riparian restoration projects using Landsat and precipitation data from the cloud-computing application ClimateEngine.org",2018,"10.1016/j.ecoleng.2018.06.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049463747&doi=10.1016%2fj.ecoleng.2018.06.024&partnerID=40&md5=8b604733644729e950ccac672aa97449","Riparian vegetation along streams provides a suite of ecosystem services in rangelands and thus is the target of restoration when degraded by over-grazing, erosion, incision, or other disturbances. Assessments of restoration effectiveness depend on defensible monitoring data, which can be both expensive and difficult to collect. We present a method and case study to evaluate the effectiveness of restoration of riparian vegetation using a web-based cloud-computing and visualization tool (ClimateEngine.org) to access and process remote sensing and climate data. Restoration efforts on an Eastern Oregon ranch were assessed by analyzing the riparian areas of four creeks that had in-stream restoration structures constructed between 2008 and 2011. Within each study area, we retrieved spatially and temporally aggregated values of summer (June, July, August) normalized difference vegetation index (NDVI) and total precipitation for each water year (October-September) from 1984 to 2017. We established a pre-restoration (1984–2007) linear regression between total water year precipitation and summer NDVI for each study area, and then compared the post-restoration (2012–2017) data to this pre-restoration relationship. In each study area, the post-restoration NDVI-precipitation relationship was statistically distinct from the pre-restoration relationship, suggesting a change in the fundamental relationship between precipitation and NDVI resulting from stream restoration. We infer that the in-stream structures, which raised the water table in the adjacent riparian areas, provided additional water to the streamside vegetation that was not available before restoration and reduced the dependence of riparian vegetation on precipitation. This approach provides a cost-effective, quantitative method for assessing the effects of stream restoration projects on riparian vegetation. © 2018 The Authors"
"57203690376;8916335600;6603381720;","Investigating the relative contributions of charge deposition and turbulence in organizing charge within a thunderstorm",2018,"10.1175/JAS-D-18-0007.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052625954&doi=10.1175%2fJAS-D-18-0007.1&partnerID=40&md5=17dbc737ce8b0b9eca376c52804291ee","Large-eddy-resolving simulations using the Collaborative Model for Multiscale Atmospheric Simulation (COMMAS), which contains microphysical charging and branched-lightning parameterizations, produce much more complex net charge structures than conventionally visualized from previous observations, simulations, and conceptual diagrams. Many processes contribute to the hydrometeor charge budget within a thunderstorm, including advection, hydrometeor differential sedimentation, subgrid turbulent mixing and diffusion, ion drift, microphysical separation, and the attachment of ion charge deposited by the lightning channel. The lightning deposition, sedimentation, and noninductive charging tendencies contribute the most overall charge at relatively large scales, while the advection tendency, from resolved turbulence, provides the most ""texture"" at small scales to the net charge density near the updraft region of the storm. The scale separation increases for stronger storm simulations. In aggregate, lightning deposition and sedimentation resemble the smoother distribution of the electric potential, while evidence suggests individual flashes could be responding to the fine texture in the net charge. The clear scale separation between the advection and other net charge tendencies suggest the charge advection is most capable of providing net charge texture; however, a clear-cut causality is not obtained from this study. © 2018 American Meteorological Society."
"7102167757;16202694600;55249801100;14023953700;29067574800;34978268900;9244992800;34771961800;26655075300;35094424100;14020798200;15724418700;56740490500;","Revisiting the relationship among metrics of tropical expansion",2018,"10.1175/JCLI-D-18-0108.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052739529&doi=10.1175%2fJCLI-D-18-0108.1&partnerID=40&md5=fc391bb174fb0bd810aabc071049215a","There is mounting evidence that the width of the tropics has increased over the last few decades, but there are large differences in reported expansion rates. This is, likely, in part due to the wide variety of metrics that have been used to define the tropical width. Here we perform a systematic investigation into the relationship among nine metrics of the zonal-mean tropical width using preindustrial control and abrupt quadrupling of CO2 simulations from a suite of coupled climate models. It is shown that the latitudes of the edge of the Hadley cell, the midlatitude eddy-driven jet, the edge of the subtropical dry zones, and the Southern Hemisphere subtropical high covary interannually and exhibit similar long-term responses to a quadrupling of CO2. However, metrics based on the outgoing longwave radiation, the position of the subtropical jet, the break in the tropopause, and theNorthernHemisphere subtropical high have very weak covariations with the abovemetrics and/or respond differently to increases in CO2 and thus are not good indicators of the expansion of the Hadley cell or subtropical dry zone. The differing variability and responses to increases in CO2 amongmetrics highlights that care is needed when choosing metrics for studies of the width of the tropics and that it is important tomake sure the metric used is appropriate for the specific phenomena and impacts being examined. © 2018 American Meteorological Society."
"57216384164;55585574900;57208195228;12807776900;57204555899;","Security Performance Evaluation of Minehunting Equipment in the Cloud Computing Environment",2018,"10.2112/SI82-018.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056876715&doi=10.2112%2fSI82-018.1&partnerID=40&md5=d4fa3c2634d0da02760ea8c78529d9d5","Zhang, S.; Sun, L.; Liu, Y.; Wu, Q., and Xu, K., 2018. Security performance evaluation of minehunting equipment in the cloud computing environment. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia. For sea minehunting with a complex structure, index selection by the conventional evaluation method is not reasonable; it has strong subjectivity, resulting in distortion of evaluation results. Therefore, the combination of qualitative and quantitative analysis is used to carry out the safety performance evaluation of sea minehunting equipment. By using the method of qualitative analysis, the evaluation index system of the safety performance of minehunting equipment can be established; expert experience and knowledge are transformed into the comparison of important degrees of each index to get the quantitative characterization of the important degrees. The fuzzy comprehensive evaluation is used to obtain the comprehensive evaluation result of the safety performance of minehunting equipment. The results show that the method can accurately reflect the state of minehunting equipment performance. © Coastal Education and Research Foundation, Inc. 2018."
"55285875500;57209562361;57200924760;","Correlation Analysis Method for Ocean Monitoring Big Data in a Cloud Environment",2018,"10.2112/SI82-003.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056875435&doi=10.2112%2fSI82-003.1&partnerID=40&md5=b19a0575cd559d326aa510ef6ba6cf29","Song, J.; Xie, H., and Feng, Y., 2018. Correlation analysis method for ocean monitoring big data in a cloud environment. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia. The current correlation analysis method for ocean monitoring big data is time consuming, and stability is poor. A new method is proposed to overcome these problems. The ocean monitoring big data were divided into eight categories and analyzed individually, and then ocean monitoring data model, data model, ocean coast big data model, and ocean monitoring data sets were analyzed and calculated according to the spatial correlation function to determine the ocean monitoring big data spatial correlation coefficient and collect spatial correlation of ocean monitoring big data characteristic elements. Experimental results showed that the proposed method improved the speed and stability of the correlation analysis of ocean monitoring big data, and advanced the classification accuracy of ocean monitoring data by about 30%. © Coastal Education and Research Foundation, Inc. 2018."
"56332041000;24478692500;7004390513;6508152778;57204171085;55611861900;36720718800;55941606700;6701639567;7202115571;16307483000;7005056887;","Innovation in rangeland monitoring: annual, 30 m, plant functional type percent cover maps for U.S. rangelands, 1984–2017",2018,"10.1002/ecs2.2430","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054833588&doi=10.1002%2fecs2.2430&partnerID=40&md5=de119c9c5d884c6ac53fbbda435ddbe0","Innovations in machine learning and cloud-based computing were merged with historical remote sensing and field data to provide the first moderate resolution, annual, percent cover maps of plant functional types across rangeland ecosystems to effectively and efficiently respond to pressing challenges facing conservation of biodiversity and ecosystem services. We utilized the historical Landsat satellite record, gridded meteorology, abiotic land surface data, and over 30,000 field plots within a Random Forests model to predict per-pixel percent cover of annual forbs and grasses, perennial forbs and grasses, shrubs, and bare ground over the western United States from 1984 to 2017. Results were validated using three independent collections of plot-level measurements, and resulting maps display land cover variation in response to changes in climate, disturbance, and management. The maps, which will be updated annually at the end of each year, provide exciting opportunities to expand and improve rangeland conservation, monitoring, and management. The data open new doors for scientific investigation at an unprecedented blend of temporal fidelity, spatial resolution, and geographic scale. © 2018 The Authors."
"55713860900;55420675800;25825460700;","Mapping individual tree species and vitality along urban road corridors with LiDAR and imaging sensors: Point density versus view perspective",2018,"10.3390/rs10091403","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053607874&doi=10.3390%2frs10091403&partnerID=40&md5=dfabf2435a07fb576fdc6e319fc85da1","To meet a growing demand for accurate high-fidelity vegetation cover mapping in urban areas toward biodiversity conservation and assessing the impact of climate change, this paper proposes a complete approach to species and vitality classification at single tree level by synergistic use of multimodality 3D remote sensing data. So far, airborne laser scanning system (ALS or airborne LiDAR) has shown promising results in tree cover mapping for urban areas. This paper analyzes the potential of mobile laser scanning system/mobile mapping system (MLS/MMS)-based methods for recognition of urban plant species and characterization of growth conditions using ultra-dense LiDAR point clouds and provides an objective comparison with the ALS-based methods. Firstly, to solve the extremely intensive computational burden caused by the classification of ultra-dense MLS data, a new method for the semantic labeling of LiDAR data in the urban road environment is developed based on combining a conditional random field (CRF) for the context-based classification of 3D point clouds with shape priors. These priors encode geometric primitives found in the scene through sample consensus segmentation. Then, single trees are segmented from the labelled tree points using the 3D graph cuts algorithm. Multinomial logistic regression classifiers are used to determine the fine deciduous urban tree species of conversation concern and their growth vitality. Finally, the weight-of-evidence (WofE) based decision fusion method is applied to combine the probability outputs of classification results from the MLS and ALS data. The experiment results obtained in city road corridors demonstrated that point cloud data acquired from the airborne platform achieved even slightly better results in terms of tree detection rate, tree species and vitality classification accuracy, although the tree vitality distribution in the test site is less balanced compared to the species distribution. When combined with MLS data, overall accuracies of 78% and 74% for tree species and vitality classification can be achieved, which has improved by 5.7% and 4.64% respectively compared to the usage of airborne data only. © 2018 by the authors."
"56587020100;7006256622;","Long-Lived Mesoscale Convective Systems of Superparameterized CAM and the Response of CAM",2018,"10.1029/2018MS001339","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053461778&doi=10.1029%2f2018MS001339&partnerID=40&md5=a87407a35a3c885145a317a552fa1b12","Mesoscale organized convection is generally misrepresented in the large-scale convective parameterizations used in contemporary climate models. This impacts extreme weather events (e.g., Madden-Jullian Oscillation) and the general circulation driven by the significant amount of latent heat released from mesoscale organized convection. Studies show that the missing processes could be partially recovered by embedding a 2-D cloud-resolving model in each general circulation model columns, that is, superparameterization. To enable analysis of mesoscale convective systems (MCSs) in the multiscale modeling framework, we apply a detection and hierarchical clustering algorithm on the 3-hourly 2-D cloud-resolving model embedded in the superparameterized Community Atmosphere Model (SPCAM) 5.2. We then examine the fields of a long-lived and large MCS cluster at the central Pacific. The MCS cluster shows a squall line-like circulation throughout the life cycle in SPCAM. We simultaneously obtain the 3-hourly CAM parameterized convection outputs based on the time step-wise perfect initial conditions given by SPCAM. This allows pure model physics comparison without introducing initial condition errors. The results show that CAM has a systematically biased stratiform cooling and moistening response below 3 km to the given SPCAM deep convection favoring conditions. We show that this bias is mainly due to the CAM's stratiform microphysics scheme. The mesoscale organization in SPCAM thus provides a baseline for improvements of convective parameterization of CAM. ©2018. The Authors."
"37065777300;7004512139;6701344406;55418990300;7004544454;","Observed warming over northern South America has an anthropogenic origin",2018,"10.1007/s00382-017-3988-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032693045&doi=10.1007%2fs00382-017-3988-z&partnerID=40&md5=d1f16b6030f4b4adb332cbbf1386afc1","We investigate whether the recently observed trends in daily maximum and minimum near-surface air temperature (Tmax and Tmin, respectively) over South America (SA) are consistent with the simulated response of Tmin and Tmax to anthropogenic forcing. Results indicate that the recently observed warming in the dry seasons is well beyond the range of natural (internal) variability. In the wet season the natural modes of variability explain a substantial portion of Tmin and Tmax variability. We demonstrate that the large-scale component of greenhouse gas (GHG) forcing is detectable in dry-seasonal warming. However, none of the global and regional climate change projections reproduce the observed warming of up to 0.6 K/Decade in Tmax in 1983–2012 over northern SA during the austral spring (SON). Thus, besides the global manifestation of GHG forcing, other external drivers have an imprint. Using aerosols-only forcing simulations, our results provide evidence that anthropogenic aerosols also have a detectable influence in SON and that the indirect effect of aerosols on cloud’s lifetime is more compatible with the observed record. In addition, there is an increasing trend in the observed incoming solar radiation over northern SA in SON, which is larger than expected from natural (internal) variability alone. We further show that in the dry seasons the spread of projected trends based on the RCP4.5 scenario derived from 30 CMIP5 models encompasses the observed area-averaged trends in Tmin and Tmax. This may imply that the observed excessive warming in the dry seasons serve as an illustration of plausible future expected change in the region. © 2017, Springer-Verlag GmbH Germany."
"55613316200;56151424600;35106188100;8543279200;7004703836;54400240900;6602311043;","Assessing the performance of WRF model in predicting high-impact weather conditions over Central and Western Africa: an ensemble-based approach",2018,"10.1007/s11069-018-3368-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047934927&doi=10.1007%2fs11069-018-3368-y&partnerID=40&md5=381dc9e03adf5686b03582471722982d","For numerical weather prediction over a particular region, it is important to know the best combination of physical parameterizations available in the considered modelling frame work. The main objective of the study is to obtain the best combination of the weather research and forecasting (WRF) model physics for accurately simulating high-impact weather conditions, especially the rainfall over Western and Central Africa. For this purpose, performance of WRF from various simulations with specific configurations is assessed by comparing the results to the Tropical Rainfall Measurement Mission data. Each of the simulations is carried out for 30 h and initialized at 00 UTC. The spin-up time considered for the study is 6 h. A flood event (21–22 July 2010) is simulated by considering five cumulus physics schemes with multiple cloud microphysics, planetary boundary layer and land surface parameterizations. Analysis of the model results indicates that some of the physics combinations have good agreement with observations, especially the new (GFS) simplified Arakawa–Schubert and the modified Tiedtke cumulus parameterizations combined with Thompson and Morrison microphysics. However, most of the combinations over-estimated the rainfall over the study domain, while the simulations with Betts–Miller–Janjic cumulus parameterizations showed negative bias over designated regions of Africa. © 2018, Springer Science+Business Media B.V., part of Springer Nature."
"56158925300;57200702127;56158523800;55258548500;7401435616;7102423967;15821766200;7404829395;7005973015;7404865816;","Impacts of Saharan dust on Atlantic regional climate and implications for tropical cyclones",2018,"10.1175/JCLI-D-16-0776.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052926009&doi=10.1175%2fJCLI-D-16-0776.1&partnerID=40&md5=f8684749e009ae1eaea3462cf0314a67","The radiative and microphysical properties of Saharan dust are believed to impact the Atlantic regional climate and tropical cyclones (TCs), but the detailed mechanism remains uncertain. In this study, atmosphereonly simulations are performed from 2002 to 2006 using the Community Atmospheric Model, version 5.1, with and without dust emission from the Sahara Desert. The Saharan dust exhibits noticeable impacts on the regional longwave and shortwave radiation, cloud formation, and the convective systems over West Africa and the tropical Atlantic. The African easterly jet and West African monsoon are modulated by dust, leading to northward shifts of the intertropical convergence zone and the TC genesis region. The dust events induce positive midlevel moisture and entropy deficit anomalies, enhancing the TC genesis. On the other hand, the increased vertical wind shear and decreased low-level vorticity and potential intensity by dust inhibit TC formation in the genesis region. The ventilation index shows a decrease in the intensification region and an increase in the genesis region by dust, corresponding to favorable and unfavorable TC activities, respectively. The comparison of nondust scenarios in 2005 and 2006 shows more favorable TC conditions in 2005 characterized by higher specific humidity and potential intensity, but lower ventilation index, wind shear, and entropy deficit. Those are attributable to the observed warmer sea surface temperature (SST) in 2005, in which dust effects can be embedded. Our results imply significant dust perturbations on the radiative budget, hydrological cycle, and large-scale environments relevant to TC activity over the Atlantic. © 2018 American Meteorological Society."
"7404433688;55953758400;57193494974;55386235300;35847805400;56969650900;56082867500;55969140000;35337273500;","Precipitation characteristics over the steep slope of the Himalayas in rainy season observed by TRMM PR and VIRS",2018,"10.1007/s00382-017-3992-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033446598&doi=10.1007%2fs00382-017-3992-3&partnerID=40&md5=c8157ed7976bc14f73a457ac619d917e","Characteristics of the precipitation in rainy season over the steep Himalayas and adjacent regions, including four selected sectors of the flat Gangetic Plains (FGP), foothills of the Himalayas (FHH), the steep slope of the southern Himalayas (SSSH), and the Himalayan–Tibetan Plateau tableland (HTPT), are investigated using collocated satellite datasets from the TRMM PR and VIRS at pixel level during May–August of 1998–2012. Results indicate that the rain frequency increases significantly from the FGP via FHH to the lower elevations of the SSSH (~ 2.5 km), then decreases as the elevation further increases up to the HTPT, and reaches the minimum over the HTPT. Along with such spatial variation of the rain frequency, mean rain rates (RRs) are the heaviest over the FGP (4 mm h−1) and the FHH (5.5 mm h−1), medium over the SSSH (2–4 mm h−1), and the weakest over the HTPT (less than 2 mm h−1). More than 60% of precipitation over the FGP, FHH, and HTPT is produced by ice-phase topped clouds, while more than 70% over the SSSH is from mixed-phase topped clouds. Analysis suggests that the highest rain frequency over the SSSH in rainy season may be caused by a strong upward motion over the SSSH as warm moist air monsoon flow interacting with the terrain of the Himalayas, while the heaviest RR over the FHH may result from low-level convergence where the air flow is blocked by the SSSH. The elevation and relief effects have linear relationships with precipitation over the south sub-region of the SSSH, which indicates that both effects play important roles on precipitation over complex plateau topography. © 2017, Springer-Verlag GmbH Germany."
"57105719400;57204721886;57105452800;","An Internet of Things-based Simulation Study on Lijiang River Water Environment Monitoring",2018,"10.2112/SI82-014.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056909968&doi=10.2112%2fSI82-014.1&partnerID=40&md5=152977fb02feeebf006f262a49e18779","Biqing, L.; Xiaomei, Y., and Shiyong, Z., 2018. An Internet of Things-based simulation study on Lijiang River water environment monitoring. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia. The Internet of Things platform for environmental monitoring of the Lijiang River water, based on the representational state-transfer structure, is proposed in response to problems, such as an insufficient monitoring site, high complexity, and poor extendibility. The sensor node and node-state data were abstracted into resources, whose characteristics of concision, high efficiency, and loose coupling could satisfy the requirements of Lijiang River water-environment monitoring. The Alibaba cloud Elastic Compute Service server was adopted to establish the developmental environment for user management, GIS, real-time data display, and historical data inquiry with the help of a Laravel structure and a lightweight jQuery front-end framework. This platform could satisfy the requirements of fishery and animal industries, scientific research institutes, and governmental sectors, and enable the sharing of monitoring data on the Lijiang River water environment. According to the simulation results, the proposed technologies have not only realized remote data acquisition and transmission of water resource monitoring in real time with high reliability but also improved the economic efficiency of the entire network's energy loss. © Coastal Education and Research Foundation, Inc. 2018."
"55192925300;55809739900;16678345700;57197746605;","Research and Application of a Big Data-Driven Intelligent Reservoir Management System",2018,"10.2112/SI82-039.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056880262&doi=10.2112%2fSI82-039.1&partnerID=40&md5=8e2264c0a32140fd59eebf9b7fb84f10","Yue, Q.; Liu, F.; Diao, Y., and Liu, Y., 2018. Research and application of a big data-driven intelligent reservoir management system. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia. In view of multisource information integration difficulties, the lack of real-time data acquisition capability, and the low level of management intelligence in current reservoir management, the intelligent monitoring node of a remote internet of things is applied for real-time acquisition of reservoir operation data and the establishment of a four-layer browser and server system framework. An intelligent reservoir management system with flexible configuration and strong scalability is developed based on the dynamic big data drive concept. The system achieves highly efficient application of the internet of things and cloud computing technology in the reservoir management field; fully considers the high demand of the massive monitoring data on the management system; integrates reservoir health and the operation of big data analysis; can conduct accurate monitoring, diagnosis, analysis, forecasting, and management optimization of the reservoir operation condition' and achieves real-time output through charts. The system's user can get a quick access to multisource data sharing and decision support services via LED display and computer and intelligent mobile terminals. The demonstration project application shows that the system has integrated application of massive data and practical, scalable, and user-friendly features, which can provide comprehensive and efficient information technology support for the intelligent management of reservoir operation and has broad application prospects. © Coastal Education and Research Foundation, Inc. 2018."
"54974135900;6602825148;","The vegetation red edge biosignature through time on earth and exoplanets",2018,"10.1089/ast.2017.1798","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053156678&doi=10.1089%2fast.2017.1798&partnerID=40&md5=044f088d7e5458dddb2dce4561d2cc89","The high reflection of land vegetation in the near-infrared, the vegetation red edge (VRE), is often cited as a spectral biosignature for surface vegetation on exoplanets. The VRE involves only a few percentage change in reflectivity for a disk-integrated observation of present-day Earth. Here we show that the strength of Earth's VRE has increased over the past ∼500 million years of land plant evolution and may continue to increase as solar luminosity increases and the planet warms, until either vegetation coverage is reduced, or the planet's atmosphere becomes opaque to light reflected off the surface. Early plants such as mosses and liverworts, which dominated the land 500-400 million years ago, produce a weaker VRE, approximately half as strong as that of modern vegetation. We explore how the changes in land plants, as well as geological changes such as ice coverage during ice ages and interglacial periods, influence the detectability of the VRE through Earth's geological past. Our results show that the VRE has varied through the evolutionary history of land plants on Earth and could continue to change into the future if hotter climate conditions became dominant, encouraging the spread of vegetation. Our findings suggest that older and hotter Earth-like planets are good targets for the search for a VRE signature. In addition, hot exoplanets and dry exoplanets with some water could be the best targets for a successful vegetation biosignature detection. As well as a strong red edge, lower cloud fractions and low levels of atmospheric water vapor on such planets could make it easier to detect surface features in general. © 2018 Mary Ann Liebert, Inc."
"55293421800;37085583300;","A climatology of strong large-scale ocean evaporation events. Part II: Relevance for the deuterium excess signature of the evaporation flux",2018,"10.1175/JCLI-D-17-0592.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052927027&doi=10.1175%2fJCLI-D-17-0592.1&partnerID=40&md5=a9b2c1c3645d2aa096df0b75df77cfd4","This paper discusses the relevance of transient events of strong large-scale ocean evaporation (SLOE) for the deuteriumexcess of marine boundary layer vapor d using a theoretical framework that invokes the closure assumption. We argue that during SLOE events, d is essentially determined by the evaporation flux signature. Distinct high d during SLOE with global-mean values in the range of 12‰-23‰ depending on the nonequilibrium fractionation factor αk result from the large air-sea humidity gradients reflected in low relative humidity with respect to sea surface temperature (hs 5 53% ± 9%) that characterize these events. Extratropical cyclones are highlighted as an important driver for the variability of d. On the one hand, they are themselves associated with high hs and low d, especially in areas of cloud formation and precipitation in the warm sector. On the other hand, cyclones are the main driver inducing SLOE events with high d in regions of cold-air advection upstream of their path. The sensitivity of d to its direct climate controls (hs and SST) is analyzed during SLOE for different αk formulations and found to be coherent with d-hs and d-SST slopes determined from available observations. The d-hs relationship exhibits a robust negative correlation as opposed to the d-SST relationship, which shows regional and time-scale-dependent variations in strength and sign that are induced by indirect hs-SST cross-correlation effects. The dynamical features involved in SLOE generation appear to exert a key control on the moisture source properties relevant for d in the extratropics. © 2018 American Meteorological Society."
"57201649134;57203923653;24178270500;6602942477;","JAXA high-resolution land use/land cover map for Central Vietnam in 2007 and 2017",2018,"10.3390/rs10091406","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053622161&doi=10.3390%2frs10091406&partnerID=40&md5=84b5b4ffda9e3d750aa0f38f8cd1d5ff","Robust remote monitoring of land cover changes is essential for a range of studies such as climate modeling, ecosystems, and environmental protection. However, since each satellite data has its own effective features, it is difficult to obtain high accuracy land cover products derived from a single satellite's data, perhaps because of cloud cover, suboptimal acquisition schedules, and the restriction of data accessibility. In this study, we integrated Landsat 5, 7, and 8, Sentinel-2, Advanced Land Observing Satellite Advanced Visual, and Near Infrared Radiometer type 2 (ALOS/AVNIR-2), ALOS Phased Array L-band Synthetic Aperture Radar (PALSAR) Mosaic, ALOS-2/PALSAR-2 Mosaic, Shuttle Radar Topography Mission (SRTM), and ancillary data, using kernel density estimation to map and analyze land use/cover change (LUCC) over Central Vietnam from 2007 to 2017. The region was classified into nine categories, i.e., water, urban, rice paddy, upland crops, grassland, orchard, forest, mangrove, and bare land by an automatic model which was trained and tested by 98,000 reference data collected from field surveys and visual interpretations. Results were the 2007 and 2017 classified maps with the same spatial resolutions of 10 m and the overall accuracies of 90.5% and 90.6%, respectively. They indicated that Central Vietnam experienced an extensive change in land cover (33 ± 18% of the total area) during the study period. Gross gains in forests (2680 km2) and water bodies (570 km2) were primarily from conversion of orchards, paddy fields, and crops. Total losses in bare land (495 km2) and paddy (485 km2) were largely to due transformation to croplands and urban & other infrastructure lands. In addition, the results demonstrated that using global land cover products for specific applications is impaired because of uncertainties and inconsistencies. These findings are essential for the development of resource management strategy and environmental studies. © 2018 by the authors."
"57110076500;57203404677;23102247400;56298191000;56599631100;","The variable infiltration capacity model version 5 (VIC-5): Infrastructure improvements for new applications and reproducibility",2018,"10.5194/gmd-11-3481-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052758696&doi=10.5194%2fgmd-11-3481-2018&partnerID=40&md5=a2ab4432f72222031c0c870ecf7d2172","The Variable Infiltration Capacity (VIC) model is a macroscale semi-distributed hydrologic model. VIC development began in the early 1990s and the model has since been used extensively for basin- to global-scale applications that include hydrologic dataset construction, trend analysis of hydrologic fluxes and states, data evaluation and assimilation, forecasting, coupled climate modeling, and climate change impact assessment. Ongoing operational applications of the VIC model include the University of Washington's drought monitoring and forecasting systems and NASA's Land Data Assimilation System. This paper documents the development of VIC version 5 (VIC-5), which includes a major reconfiguration of the legacy VIC source code to support a wider range of modern hydrologic modeling applications. The VIC source code has been moved to a public GitHub repository to encourage participation by the broader user and developer communities. The reconfiguration has separated the core physics of the model from the driver source code, whereby the latter is responsible for memory allocation, preprocessing and post-processing, and input-output (I-O). VIC-5 includes four drivers that use the same core physics modules, but which allow for different methods for accessing this core to enable different model applications. Finally, VIC-5 is distributed with robust test infrastructure, components of which routinely run during development using cloud-hosted continuous integration. The work described here provides an example to the model development community for extending the life of a legacy model that is being used extensively. The development and release of VIC-5 represents a significant step forward for the VIC user community in terms of support for existing and new model applications, reproducibility, and scientific robustness. © Author(s) 2018."
"56502000100;57195805362;8899985400;55729666100;7004462227;26639062900;","The diverse chemical mixing state of aerosol particles in the southeastern United States",2018,"10.5194/acp-18-12595-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052736450&doi=10.5194%2facp-18-12595-2018&partnerID=40&md5=459ccf6253ea097372c24f727cb13984","Aerosols in the atmosphere are chemically complex with thousands of chemical species distributed in different proportions across individual particles in an aerosol population. An internal mixing assumption, with species present in the same proportions across all aerosols, is used in many models and calculations of secondary organic aerosol (SOA) formation, cloud activation, and aerosol optical properties. However, many of these effects depend on the distribution of species within individual particles, and important information can be lost when internal mixtures are assumed. Herein, we show that - as found during the Southern Oxidant and Aerosol Study (SOAS) in Centreville, Alabama, at a rural, forested location - aerosols frequently are not purely internally mixed, even in the accumulation mode (0.2-1.0μm). A range of aerosol sources and the mixing state were determined using computer-controlled scanning electron microscopy with energy-dispersive X-ray spectroscopy (CCSEM-EDX) and scanning transmission X-ray microscopy-near-edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS). Particles that were dominated by SOA and inorganic salts (e.g., ammonium sulfate) were the majority of particles by number fraction from 0.2 to 5μm with an average of 78% SOA in the accumulation mode. However, during certain periods contributions by sea spray aerosol (SSA) and mineral dust were significant to accumulation (22% SSA and 26% dust) and coarse-mode number concentrations (38% SSA and 63% dust). The fraction of particles containing key elements (Na, Mg, K, Ca, and Fe) were determined as a function of size for specific classes of particles. Within internally mixed SOA/sulfate particles <5% contained Na, Mg, K, Ca, or Fe, though these nonvolatile cations were present in particles from the other sources (e.g., SSA and dust). Mass estimates of the aerosol elemental components were used to determine the extent of internal versus external mixing by calculating the mixing state index (χ). The aerosol population was more externally mixed than internally mixed during all time periods analyzed. Accumulation mode aerosol ranged from more internally mixed during SOA periods to mostly externally mixed during dust periods. Supermicron aerosols were most externally mixed during SOA time periods, when more SOA particles added a distinct supermicron class, and more internally mixed when dominated by a single particle type (e.g., SSA or dust). These results emphasize that neither external nor internal mixtures fully represent the mixing state of atmospheric aerosols, even in a rural, forested environment, which has important implications for air quality and climate modeling. © 2018 American Institute of Physics Inc. All rights reserved."
"57202831187;28367935500;7003696273;36765524100;","Robust and Nonrobust Impacts of Atmospheric Cloud-Radiative Interactions on the Tropical Circulation and Its Response to Surface Warming",2018,"10.1029/2018GL079599","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053274624&doi=10.1029%2f2018GL079599&partnerID=40&md5=b850bc8a78e301afbc4e910a468a882d","The impact of cloud-radiative interactions on the tropical circulation and its response to surface warming are studied in aquaplanet model simulations with prescribed sea-surface temperatures from eight global atmosphere models. Simulations with enabled and disabled cloud-radiative interactions are compared. In a present-day-like climate, the presence of cloud-radiative interactions strengthens the Hadley cell, narrows and strengthens tropical ascent, and widens subtropical descent. These cloud impacts are robust across models and are shown to be related to the energetics and mass constraints of the tropical atmosphere. Cloud-radiative interactions have no robust impact on the circulation response to surface warming but amplify model differences in the response of the ascent and the Hadley cell strength. The lack of robust cloud impacts is consistent with the fact that surface warming-induced changes in atmospheric cloud-radiative effects are small compared to the cloud-radiative effects in the present-day-like climate. ©2018. American Geophysical Union. All Rights Reserved."
"55509658400;57207222073;56263595100;57203397955;","CloudNet: Ground-Based Cloud Classification With Deep Convolutional Neural Network",2018,"10.1029/2018GL077787","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053182365&doi=10.1029%2f2018GL077787&partnerID=40&md5=fe2dc5a34c57e468c88b67539ac6a72c","Clouds have an enormous influence on the Earth's energy balance, climate, and weather. Cloud types have different cloud radiative effects, which is an essential indicator of the cloud effect on radiation. Therefore, identifying the cloud type is important in meteorology. In this letter, we propose a new convolutional neural network model, called CloudNet, for accurate ground-based meteorological cloud classification. We build a ground-based cloud data set, called Cirrus Cumulus Stratus Nimbus, which consists of 11 categories under meteorological standards. The total number of cloud images is three times that of the previous database. In particular, it is the first time that contrails, a type of cloud generated by human activity, have been taken into account in the ground-based cloud classification, making the Cirrus Cumulus Stratus Nimbus data set more discriminative and comprehensive than existing ground-based cloud databases. The evaluation of a large number of experiments demonstrates that the proposed CloudNet model could achieve good performance in meteorological cloud classification. ©2018. American Geophysical Union. All Rights Reserved."
"56020125200;6507206337;57203078745;7005939834;56389356400;7003627515;","Evaluation of Reconstructions of Snow/Ice Melt in Greenland by Regional Atmospheric Climate Models Using Laser Altimetry Data",2018,"10.1029/2018GL078645","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053200667&doi=10.1029%2f2018GL078645&partnerID=40&md5=8842a4236ef84bd7fee4231f08c170cf","The surface mass balance of the Greenland ice sheet critically depends on the intensity of ice melt/snowmelt in its ablation zone, but in situ data have been too limited to quantify the error of regional climate models. Here we use 23 years of NASA satellite and airborne laser altimetry from the Airborne Topographic Mapper; Land, Vegetation, and Ice Sensor; and Ice, Cloud, and land Elevation Satellite to generate time series of elevation change to compare with surface mass balance products from the Regional Atmospheric Climate Model and from the Modèle Atmosphérique Régional. For 1994–2016, the results agree at the 15–26% level, with the largest discrepancy in North Greenland. During the cold summer of 2015, the root-mean-square discrepancy is 40% in the north, 30% in the southwest, and 18–25% at low elevation. The difference drops to 23% in the southwest and 14% at low elevation during the 2016 warm summer. ©2018. American Geophysical Union. All Rights Reserved."
"54994166900;56592923300;57193537889;55277349200;7102862273;7006599647;9235235300;","Cloud droplet activation of black carbon particles coated with organic compounds of varying solubility",2018,"10.5194/acp-18-12477-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052741426&doi=10.5194%2facp-18-12477-2018&partnerID=40&md5=b7b95aa1f939fcf576cf7110cd3d5f77","Atmospheric black carbon (BC) particles are a concern due to their impact on air quality and climate. Their net climate effect is, however, still uncertain. This uncertainty is partly related to the contribution of coated BC particles to the global cloud condensation nuclei (CCN) budgets. In this study, laboratory measurements were performed to investigate CCN activity of BC (REGAL 400R pigment black) particles, in pure state or coated through evaporating and subsequent condensation of glutaric acid, levoglucosan (both water-soluble organics) or oleic acid (an organic compound with low solubility). A combination of soot particle aerosol mass spectrometer (SP-AMS) measurements and size distribution measurements with a scanning mobility particle sizer (SMPS) showed that the studied BC particles were nearly spherical agglomerates with a fractal dimension of 2.79 and that they were coated evenly by the organic species. The CCN activity of BC particles increased after coating with all the studied compounds and was governed by the fraction of organic material. The CCN activation of the BC particles coated by glutaric acid and levoglucosan were in good agreement with the theoretical calculations using the shell-and-core model, which is based on a combination of the CCN activities of the pure compounds. The oleic acid coating enhanced the CCN activity of the BC particles, even though the pure oleic acid particles were CCN inactive. The surprising effect of oleic acid might be related to the arrangement of the oleic acid molecules on the surface of the BC cores or other surface phenomena facilitating water condensation onto the coated particles. Our results show that present theories have potential for accurately predicting the CCN activity of atmospheric BC coated with organic species, given that the identities and amounts of the coating species are known. Furthermore, our results suggest that even relatively thin soluble coatings (around 2nm for the compounds studied here) are enough to make the insoluble BC particles CCN active at typical atmospheric supersaturations and thus be efficiently taken up by cloud droplets. This highlights the need for an accurate description of the composition of atmospheric particles containing BC to unravel their net impact on climate. © 2018 Author(s)."
"24329376600;57203049177;23486734100;55437450100;55332348600;8696069500;7201485519;36809017200;35547807400;22958780000;","Accounting for Changing Temperature Patterns Increases Historical Estimates of Climate Sensitivity",2018,"10.1029/2018GL078887","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053282757&doi=10.1029%2f2018GL078887&partnerID=40&md5=feb430341d6a77eb94e72eeedab42a39","Eight atmospheric general circulation models (AGCMs) are forced with observed historical (1871–2010) monthly sea surface temperature and sea ice variations using the Atmospheric Model Intercomparison Project II data set. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However, the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a pattern effect, whereby the pattern of observed historical sea surface temperature change gives rise to more negative cloud and longwave clear-sky feedbacks. Assuming the patterns of long-term temperature change simulated by models, and the radiative response to them, are credible; this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the long-term Otto et al. (2013, https://doi.org/10.1038/ngeo1836) EffCS median and 5–95% confidence interval from 1.9 K (0.9–5.0 K) to 3.2 K (1.5–8.1 K). © 2018 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland."
"15032788000;56127067100;7103119050;","Thermodynamic Constraints on the Size Distributions of Tropical Clouds",2018,"10.1029/2018JD028803","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052807729&doi=10.1029%2f2018JD028803&partnerID=40&md5=33f03ef9a427c8f8709778ffb603479a","Tropical convective clouds evolve over a wide range of temporal and spatial scales, which makes them difficult to simulate numerically. Here we propose that cloud statistical properties can be derived within a simplified time-independent coordinate system of cloud number n, saturated static energy h⋆, and cloud perimeter λ. Under the constraint that circulations around cloud edge compete with each other for total buoyant energy and air, we show that the product of cloud number and cloud perimeter nλ is invariant with λ and that cloud number follows a negative exponential with respect to cloud-edge deviations of h⋆ with respect to the mean. Overall, the summed perimeter of all clouds scales as the square root of the atmospheric static stability. These theoretical results suggest that the complexity of cloud field structures can be viewed statistically as an emergent property of atmospheric bulk thermodynamics. Comparison with a detailed tropical cloud field simulation shows general agreement to within ≤13%. For the sake of developing hypotheses about cloud temporal evolution that are testable in high resolution simulations, the shapes of tropical cloud perimeter distributions are predicted to be invariant as climate warms, although with a modest increase in total cloud amount. ©2018. American Geophysical Union. All Rights Reserved."
"56507271700;56507358300;","Circulation-Conditioned Wintertime Temperature Bias in EURO-CORDEX Regional Climate Models Over Central Europe",2018,"10.1029/2018JD028503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052816364&doi=10.1029%2f2018JD028503&partnerID=40&md5=796225779acb8a5e330dbe49a1080f54","We analyze circulation-conditioned wintertime temperature biases in regional climate models (RCMs) over Central Europe and link them to simulation of cold days. Daily minimum and maximum temperatures from the European Coordinated Regional Climate Downscaling Experiment RCMs are evaluated against reference data from the E-OBS gridded data set. Flow direction is analyzed through u- and v-wind components at the 850-hPa pressure level taken from the ERA-Interim reanalysis. Cloud cover and snow-area fraction from the same reanalysis are used to associate the temperature biases with physical mechanisms. Distribution of flow directions during cold days is evaluated using efficiency coefficients, calculated as ratios of the relative abundance of flow directions during cold days and their wintertime climatology. RCMs driven by the reanalysis have both positive and negative minimum temperature biases, ranging from +0.7 to −2.7 °C. By contrast, all reanalysis-driven RCMs have negative maximum temperature biases, especially during northerly and westerly advection, which is probably related to overestimated cloud cover. The too-cold westerly and northerly flows are associated with an overestimated number of cold days and relatively high values of efficiency coefficients under these directions. Efficiency coefficients are simulated better under southeasterly advection, during which the temperature bias tends to be the lowest. The results suggest that simulated cold events should be analyzed and interpreted with caution, since they may develop also under zonal flow in some models, which contradicts observations. ©2018. American Geophysical Union. All Rights Reserved."
"57189624495;22133430700;55915046600;56472428200;6603624776;8413672100;23017945100;37062135300;","Impact of the Generation and Activation of Sea Salt Aerosols on the Evolution of Tropical Cyclone Dumile",2018,"10.1029/2017JD028125","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052379035&doi=10.1029%2f2017JD028125&partnerID=40&md5=171d832e4269f4ec873d2c9d51336a60","An original coupling between an aerosol scheme and a two-moment microphysics scheme has been developed in the cloud-resolving model Meso-NH to fully represent the aerosol-microphysics-dynamics interactions in tropical cyclones. A first evaluation of this coupling is performed through the simulation of tropical cyclone Dumile (2013) in the South-West Indian Ocean. MACC (Monitoring Atmospheric Composition and Climate project) analysis and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data agree about the predominance of sea salt aerosols. The aerosol-microphysics coupled system reproduces the track and intensity of Dumile well, with a transition from a monsoon depression to a tropical cyclone, and produces ice water contents that compare well with the DARDAR (raDAR/liDAR) product. Using a one-moment microphysics scheme produces a more intense and symmetric system tracking too far to the west. In the aerosol-microphysics coupled simulation, sea salt aerosols, the main source of cloud condensation nuclei (CCN), are preferentially produced in regions with high winds and waves, which reinforce convective asymmetries compared to the simulation with the one-moment scheme. Using a two-moment microphysics scheme without explicit sea salt emission led to a dramatic weakening of Dumile after 24 hr of simulation due to the consumption and scavenging of all interstitial CCN in the inner core. The importance of explicitly taking account of sea salt aerosol emissions associated with high winds and waves in tropical cyclones is a critical point for simulating long-lasting systems that need to generate their own CCN. ©2018. American Geophysical Union. All Rights Reserved."
"36343109300;57203658670;57203654217;7402717381;24492458800;","Precipitation characteristics and associated weather conditions on the eastern slopes of the Canadian Rockies during March-April 2015",2018,"10.5194/hess-22-4491-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052588019&doi=10.5194%2fhess-22-4491-2018&partnerID=40&md5=9b71ec155a0aae4b71c0a5c885f6c32b","Precipitation events that bring rain and snow to the Banff-Calgary area of Alberta are a critical aspect of the region's water cycle and can lead to major flooding events such as the June 2013 event that was the second most costly natural disaster in Canadian history. Because no special atmospheric-oriented observations of these events have been made, a field experiment was conducted in March and April 2015 in Kananaskis, Alberta, to begin to fill this gap. The goal was to characterize and better understand the formation of the precipitation at the surface during spring 2015 at a specific location in the Kananaskis Valley. Within the experiment, detailed measurements of precipitation and weather conditions were obtained, a vertically pointing Doppler radar was deployed and weather balloons were released. Although 17 precipitation events occurred, this period was associated with much less precipitation than normal (-35 %) and above-normal temperatures (2.5°C). Of the 133 h of observed precipitation, solid precipitation occurred 71 % of the time, mixed precipitation occurred 9 % and rain occurred 20 %. An analysis of 17 504 precipitation particles from 1181 images showed that a wide variety of crystals and aggregates occurred and approximately 63 % showed signs of riming. This was largely independent of whether flows aloft were upslope (easterly) or downslope (westerly). In the often sub-saturated surface conditions, hydrometeors containing ice occurred at temperatures as high as 9°C. Radar structures aloft were highly variable with reflectivity sometimes > 30 dBZe and Doppler velocity up to -1 m s-1, which indicates upward motion of particles within ascending air masses. Precipitation was formed in this region within cloud fields sometimes having variable structures and within which supercooled water at least sometimes existed to produce accreted particles massive enough to reach the surface through the relatively dry sub-cloud region. © Author(s) 2018."
"55706370400;57208765879;6603453147;7401793588;8832722300;56198145500;","Scale dependence of cirrus heterogeneity effects. Part II: MODIS NIR and SWIR channels",2018,"10.5194/acp-18-12105-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052435176&doi=10.5194%2facp-18-12105-2018&partnerID=40&md5=9a06f59ea121db89e0135924ed4c234c","In a context of global climate change, the understanding of the radiative role of clouds is crucial. On average, ice clouds such as cirrus have a significant positive radiative effect, but under some conditions the effect may be negative. However, many uncertainties remain regarding the role of ice clouds on Earth's radiative budget and in a changing climate. Global satellite observations are particularly well suited to monitoring clouds, retrieving their characteristics and inferring their radiative impact. To retrieve ice cloud properties (optical thickness and ice crystal effective size), current operational algorithms assume that each pixel of the observed scene is plane-parallel and homogeneous, and that there is no radiative connection between neighboring pixels. Yet these retrieval assumptions are far from accurate, as real radiative transfer is 3-D. This leads to the plane-parallel and homogeneous bias (PPHB) plus the independent pixel approximation bias (IPAB), which impacts both the estimation of top-of-the-atmosphere (TOA) radiation and the retrievals. An important factor that determines the impact of these assumptions is the sensor spatial resolution. High-spatial-resolution pixels can better represent cloud variability (low PPHB), but the radiative path through the cloud can involve many pixels (high IPAB). In contrast, low-spatial-resolution pixels poorly represent the cloud variability (high PPHB), but the radiation is better contained within the pixel field of view (low IPAB). In addition, the solar and viewing geometry (as well as cloud optical properties) can modulate the magnitude of the PPHB and IPAB. In this, Part II of our study, we simulate TOA 0.86 and 2.13μm solar reflectances over a cirrus uncinus scene produced by the 3DCLOUD model. Then, 3-D radiative transfer simulations are performed with the 3DMCPOL code at spatial resolutions ranging from 50m to 10km, for 12 viewing geometries and nine solar geometries. It is found that, for simulated nadir observations taken at resolution higher than 2.5km, horizontal radiation transport (HRT) dominates biases between 3-D and 1-D reflectance calculations, but these biases are mitigated by the side illumination and shadowing effects for off-zenith solar geometries. At resolutions coarser than 2.5km, PPHB dominates. For off-nadir observations at resolutions higher than 2.5km, the effect that we call THEAB (tilted and homogeneous extinction approximation bias) due to the oblique line of sight passing through many cloud columns contributes to a large increase of the reflectances, but 3-D radiative effects such as shadowing and side illumination for oblique Sun are also important. At resolutions coarser than 2.5km, the PPHB is again the dominant effect. The magnitude and resolution dependence of PPHB and IPAB is very different for visible, near-infrared and shortwave infrared channels compared with the thermal infrared channels discussed in Part I of this study. The contrast of 3-D radiative effects between solar and thermal infrared channels may be a significant issue for retrieval techniques that simultaneously use radiative measurements across a wide range of solar reflectance and infrared wavelengths. © Author(s) 2018."
"10739072200;57214611556;55603297400;11339750700;26643041500;35461255500;","Comprehensive analysis of particle growth rates from nucleation mode to cloud condensation nuclei in boreal forest",2018,"10.5194/acp-18-12085-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052450252&doi=10.5194%2facp-18-12085-2018&partnerID=40&md5=d356e88edf20135f56d4076990f5603c","Growth of aerosol particles to sizes at which they can act as cloud condensation nuclei (CCN) is a crucial factor in estimating the current and future impacts of aerosol-cloud-climate interactions. Growth rates (GRs) are typically determined for particles with diameters (dP) smaller than 40nm immediately after a regional new particle formation (NPF) event. These growth rates are often taken as representatives for the particle growth to CCN sizes (dP > 50-100nm). In modelling frameworks, the concentration of the condensable vapours causing the growth is typically calculated with steady state assumptions, where the condensation sink (CS) is the only loss term for the vapours. Additionally, the growth to CCN sizes is represented with the condensation of extremely low-volatility vapours and gas-particle partitioning of semi-volatile vapours. Here, we use a novel automatic method to determine growth rates from below 10nm to hundreds of nanometres from a 20-year-long particle size distribution (PSD) data set in boreal forest. With this method, we are able to detect growth rates also at times other than immediately after a NPF event. We show that the GR increases with an increasing oxidation rate of monoterpenes, which is closely coupled with the ambient temperature. Based on our analysis, the oxidation reactions of monoterpenes with ozone, hydroxyl radical and nitrate radical all are capable of producing vapours that contribute to the particle growth in the studied size ranges. We find that GR increases with particle diameter, resulting in up to 3-fold increases in GRs for particles with dP ∼ 100nm in comparison to those with dP ∼ 10nm. We use a single particle model to show that this increase in GR can be explained with aerosol-phase reactions, in which semi-volatile vapours form non-volatile dimers. Finally, our analysis reveals that the GR of particles with dP < 100nm is not limited by the condensation sink, even though the GR of larger particles is. Our findings suggest that in the boreal continental environment, the formation of CCN from NPF or sub-100nm emissions is more effective than previously thought and that the formation of CCN is not as strongly self-limiting a process as the previous estimates have suggested. © Author(s) 2018."
"55831437900;57206503877;","Changes in clouds and thermodynamics under solar geoengineering and implications for required solar reduction",2018,"10.5194/acp-18-11905-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051952447&doi=10.5194%2facp-18-11905-2018&partnerID=40&md5=a90e83613457029a24067131b30753bc","The amount of solar constant reduction required to offset the global warming from an increase in atmospheric CO2 concentration is an interesting question with implications for assessing the feasibility of solar geoengineering scenarios and for improving our theoretical understanding of Earth's climate response to greenhouse gas and solar forcings. This study investigates this question by analyzing the results of 11 coupled atmosphere-ocean global climate models running experiment G1 of the Geoengineering Model Intercomparison Project, in which CO2 concentrations are abruptly quadrupled and the solar constant is simultaneously reduced by an amount tuned to maintain the top-of-atmosphere energy balance and pre-industrial global mean temperature. The required solar constant reduction in G1 is between 3.2 % and 5.0 %, depending on the model, and is uncorrelated with the models' equilibrium climate sensitivity, while a formula from the experiment specifications based on the models' effective CO2 forcing and planetary albedo is well correlated with but consistently underpredicts the required solar reduction. We propose an explanation for the required solar reduction based on CO2 instantaneous forcing and the sum of radiative adjustments to the combined CO2 and solar forcings. We quantify these radiative adjustments in G1 using established methods and explore changes in atmospheric temperature, humidity, and cloud fraction in order to understand the causes of these radiative adjustments.
Comparisons of RACMO2 model output with several independent observational data show that the existing biases in AIS temperature, radiative fluxes and SMB components are further reduced with respect to the previous model version. The model-integrated annual average SMB for the ice sheet including ice shelves (minus the Antarctic Peninsula, AP) now amounts to 2229ĝ€Gtĝ€yĝ'1, with an interannual variability of 109ĝ€Gtĝ€yĝ'1. The largest improvement is found in modelled surface snowmelt, which now compares well with satellite and weather station observations. For the high-resolution ( ĝ1/4 ĝ€5.5ĝ€km) AP simulation, results remain comparable to earlier studies.
The updated model provides a new, high-resolution data set of the contemporary near-surface climate and SMB of the AIS; this model version will be used for future climate scenario projections in a forthcoming study. © Author(s) 2018."
"6603118486;37056101400;6602080205;6506298579;7404747615;","The effect of South American biomass burning aerosol emissions on the regional climate",2018,"10.5194/acp-18-5321-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045949188&doi=10.5194%2facp-18-5321-2018&partnerID=40&md5=dc26d763b6c59b6235d333112eb05a20","The impact of biomass burning aerosol (BBA) on the regional climate in South America is assessed using 30-year simulations with a global atmosphere-only configuration of the Met Office Unified Model. We compare two simulations of high and low emissions of biomass burning aerosol based on realistic interannual variability. The aerosol scheme in the model has hygroscopic growth and optical properties for BBA informed by recent observations, including those from the recent South American Biomass Burning Analysis (SAMBBA) intensive aircraft observations made during September 2012. We find that the difference in the September (peak biomass emissions month) BBA optical depth between a simulation with high emissions and a simulation with low emissions corresponds well to the difference in the BBA emissions between the two simulations, with a 71.6ĝ€% reduction from high to low emissions for both the BBA emissions and the BB AOD in the region with maximum emissions (defined by a box of extent 5-25°ĝ€S, 40-70°ĝ€W, used for calculating mean values given below). The cloud cover at all altitudes in the region of greatest BBA difference is reduced as a result of the semi-direct effect, by heating of the atmosphere by the BBA and changes in the atmospheric stability and surface fluxes. Within the BBA layer the cloud is reduced by burn-off, while the higher cloud changes appear to be responding to stability changes. The boundary layer is reduced in height and stabilized by increased BBA, resulting in reduced deep convection and reduced cloud cover at heights of 9-14ĝ€km, above the layer of BBA. Despite the decrease in cloud fraction, September downwelling clear-sky and all-sky shortwave radiation at the surface is reduced for higher emissions by 13.77ĝ€±ĝ€0.39ĝ€Wĝ€mĝ'2 (clear-sky) and 7.37ĝ€±ĝ€2.29ĝ€Wĝ€mĝ'2 (all-sky), whilst the upwelling shortwave radiation at the top of atmosphere is increased in clear sky by 3.32ĝ€±ĝ€0.09 Wĝ€mĝ'2, but decreased by ĝ'1.36±1.67ĝ€Wĝ€mĝ'2 when cloud changes are included. Shortwave heating rates increase in the aerosol layer by 18ĝ€% in the high emissions case. The mean surface temperature is reduced by 0.14ĝ€±ĝ€0.24ĝ€°C and mean precipitation is reduced by 14.5ĝ€% in the peak biomass region due to both changes in cloud cover and cloud microphysical properties. If the increase in BBA occurs in a particularly dry year, the resulting reduction in precipitation may exacerbate the drought. The position of the South Atlantic high pressure is slightly altered by the presence of increased BBA, and the strength of the southward low-level jet to the east of the Andes is increased. There is some evidence that some impacts of increased BBA persist through the transition into the monsoon, particularly in precipitation, but the differences are only statistically significant in some small regions in November. This study therefore provides an insight into how variability in deforestation, realized through variability in biomass burning emissions, may contribute to the South American climate, and consequently on the possible impacts of future changes in BBA emissions. © Author(s) 2018."
"54410286000;57189225001;25648263800;6602115068;","Spatial distribution analysis of the OMI aerosol layer height: A pixel-by-pixel comparison to CALIOP observations",2018,"10.5194/amt-11-2257-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045956346&doi=10.5194%2famt-11-2257-2018&partnerID=40&md5=b2e2e7315cd4bdeb8f8a1944897f5ff6","A global picture of atmospheric aerosol vertical distribution with a high temporal resolution is of key importance not only for climate, cloud formation, and air quality research studies but also for correcting scattered radiation induced by aerosols in absorbing trace gas retrievals from passive satellite sensors. Aerosol layer height (ALH) was retrieved from the OMI 477ĝ€nm O2 ĝ' O2 band and its spatial pattern evaluated over selected cloud-free scenes. Such retrievals benefit from a synergy with MODIS data to provide complementary information on aerosols and cloudy pixels. We used a neural network approach previously trained and developed. Comparison with CALIOP aerosol level 2 products over urban and industrial pollution in eastern China shows consistent spatial patterns with an uncertainty in the range of 462-648ĝ€m. In addition, we show the possibility to determine the height of thick aerosol layers released by intensive biomass burning events in South America and Russia from OMI visible measurements. A Saharan dust outbreak over sea is finally discussed. Complementary detailed analyses show that the assumed aerosol properties in the forward modelling are the key factors affecting the accuracy of the results, together with potential cloud residuals in the observation pixels. Furthermore, we demonstrate that the physical meaning of the retrieved ALH scalar corresponds to the weighted average of the vertical aerosol extinction profile. These encouraging findings strongly suggest the potential of the OMI ALH product, and in more general the use of the 477ĝ€nm O2 ĝ' O2 band from present and future similar satellite sensors, for climate studies as well as for future aerosol correction in air quality trace gas retrievals. © Author(s) 2018."
"56596353200;56483153400;12143775300;24802472000;","Physical responses of convective heavy rainfall to future warming condition: Case study of the hiroshima event",2018,"10.3389/feart.2018.00035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046992894&doi=10.3389%2ffeart.2018.00035&partnerID=40&md5=26783db687b16f825e03a39c5dc223be","An extreme precipitation event happened at Hiroshima in 2014. Over 200 mm of total rainfall was observed on the night of August 19th, which caused floods and many landslides. The rainfall event was estimated to be a rare event happening once in approximately 30 years. The physical response of this event to the change of the future atmospheric condition, which includes a temperature increase on average and convective stability change, is investigated in the present study using a 27-member ensemble experiment and pseudo global warming downscaling method. The experiment is integrated using the Japan Meteorological Research Institute non-hydrostatic regional climate model. A very high-resolution horizontal grid, 500 m, is used to reproduce dense cumulonimbus cloud formation causing heavy rainfall in the model. The future climate condition determined by a higher greenhouse gas concentration is prescribed to the model, in which the surface air temperature globally averaged is 4 K warmer than that in the preindustrial era. The total amounts of precipitation around the Hiroshima area in the future experiments are closer to or slightly lower than in the current experiments in spite of the increase in water vapor due to the atmospheric warming. The effect of the water vapor increase on extreme precipitation is found to be canceled out by the suppression of convection due to the thermal stability enhancement. The fact that future extreme precipitation like the Hiroshima event is not intensified is in contrast to the well-known result that extreme rainfall tends to be intensified in the future. The results in the present study imply that the response of extreme precipitation to global warming differs for each rainfall phenomenon. © 2018 Hibino, Takayabu, Wakazuki and Ogata."
"57201338569;19638935200;56962915800;7410070663;","Cloud longwave scattering effect and its impact on climate simulation",2018,"10.3390/atmos9040153","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045736682&doi=10.3390%2fatmos9040153&partnerID=40&md5=4f72d014581d008faddde6c310dbb70f","The cloud longwave (LW) scattering effect has been ignored in most current climate models. To investigate its climate impact, we apply an eight-stream DIScrete Ordinates Radiative Transfer (DISORT) scheme to include the cloud LW scattering in the General circulation model version of the LongWave Rapid Radiative Transfer Model (RRTMG_LW) and the Community Atmospheric Model Version 5 (CAM5). Results from the standalone RRTMG_LW and from diagnostic runs of CAM5 (no climate feedback) show that the cloud LW scattering reduces the upward flux at the top of the atmosphere and leads to an extra warming effect in the atmosphere. In the interactive runs with climate feedback included in CAM5, the cloud LW scattering effect is amplified by the water vapor-temperature feedback in a warmer atmosphere and has substantial influences on cloud fraction and specific humidity. The thermodynamic feedbacks are more significant in the northern hemisphere and the resulting meridional temperature gradient is different between the two hemispheres, which strengthens the southern branch of Hadley circulation, and modulates the westerly jet near 50° S and the upper part of Walker circulation. Our study concludes that the cloud LW scattering effect could have complex impacts on the global energy budget and shall be properly treated in future climate models. © 2018 by the authors."
"57201667638;23095483400;57203053317;","Prognostic parameterization of cloud ice with a single category in the aerosol-climate model ECHAM(v6.3.0)-HAM(v2.3)",2018,"10.5194/gmd-11-1557-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045687235&doi=10.5194%2fgmd-11-1557-2018&partnerID=40&md5=3cf2aabd703702c015e4b7162beef558","A new scheme for stratiform cloud microphysics has been implemented in the ECHAM6-HAM2 general circulation model. It features a widely used description of cloud water with two categories for cloud droplets and raindrops. The unique aspect of the new scheme is the break with the traditional approach to describe cloud ice analogously. Here we parameterize cloud ice by a single category that predicts bulk particle properties (P3). This method has already been applied in a regional model and most recently also in the Community Atmosphere Model 5 (CAM5). A single cloud ice category does not rely on heuristic conversion rates from one category to another. Therefore, it is conceptually easier and closer to first principles. This work shows that a single category is a viable approach to describe cloud ice in climate models. Prognostic representation of sedimentation is achieved by a nested approach for sub-stepping the cloud microphysics scheme. This yields good results in terms of accuracy and performance as compared to simulations with high temporal resolution. Furthermore, the new scheme allows for a competition between various cloud processes and is thus able to unbiasedly represent the ice formation pathway from nucleation to growth by vapor deposition and collisions to sedimentation. Specific aspects of the P3 method are evaluated. We could not produce a purely stratiform cloud where rime growth dominates growth by vapor deposition and conclude that the lack of appropriate conditions renders the prognostic parameters associated with the rime properties unnecessary. Limitations inherent in a single category are examined. © Author(s) 2018."
"56663782700;55795049300;6506144245;6701847229;7005131869;56597778200;57206531303;7003748648;","The sensitivity of alpine summer convection to surrogate climate change: An intercomparison between convection-parameterizing and convection-resolving models",2018,"10.5194/acp-18-5253-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045678525&doi=10.5194%2facp-18-5253-2018&partnerID=40&md5=dae600553d120dcc21e1ba3ea040b5c2","Climate models project an increase in heavy precipitation events in response to greenhouse gas forcing. Important elements of such events are rain showers and thunderstorms, which are poorly represented in models with parameterized convection. In this study, simulations with 12 km horizontal grid spacing (convection-parameterizing model, CPM) and 2 km grid spacing (convection-resolving model, CRM) are employed to investigate the change in the diurnal cycle of convection with warmer climate. For this purpose, simulations of 11 days in June 2007 with a pronounced diurnal cycle of convection are compared with surrogate simulations from the same period. The surrogate climate simulations mimic a future climate with increased temperatures but unchanged relative humidity and similar synoptic-scale circulation. Two temperature scenarios are compared: one with homogeneous warming (HW) using a vertically uniform warming and the other with vertically dependent warming (VW) that enables changes in lapse rate. The two sets of simulations with parameterized and explicit convection exhibit substantial differences, some of which are well known from the literature. These include differences in the timing and amplitude of the diurnal cycle of convection, and the frequency of precipitation with low intensities. The response to climate change is much less studied. We can show that stratification changes have a strong influence on the changes in convection. Precipitation is strongly increasing for HW but decreasing for the VW simulations. For cloud type frequencies, virtually no changes are found for HW, but a substantial reduction in high clouds is found for VW. Further, we can show that the climate change signal strongly depends upon the horizontal resolution. In particular, significant differences between CPM and CRM are found in terms of the radiative feedbacks, with CRM exhibiting a stronger negative feedback in the top-ofthe- Atmosphere energy budget. © Author(s) 2018."
"24404522500;14829673100;13403622000;55899443700;55777115000;7007120936;","Global radiative effects of solid fuel cookstove aerosol emissions",2018,"10.5194/acp-18-5219-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045520573&doi=10.5194%2facp-18-5219-2018&partnerID=40&md5=aa9acd25c8c8a8b5debd5df24bdf3d5c","We apply the NCAR CAM5-Chem global aerosolclimate model to quantify the net global radiative effects of black and organic carbon aerosols from global and Indian solid fuel cookstove emissions for the year 2010. Our assessment accounts for the direct radiative effects, changes to cloud albedo and lifetime (aerosol indirect effect, AIE), impacts on clouds via the vertical temperature profile (semidirect effect, SDE) and changes in the surface albedo of snow and ice (surface albedo effect). In addition, we provide the first estimate of household solid fuel black carbon emission effects on ice clouds. Anthropogenic emissions are from the IIASA GAINS ECLIPSE V5a inventory. A global dataset of black carbon (BC) and organic aerosol (OA) measurements from surface sites and aerosol optical depth (AOD) from AERONET is used to evaluate the model skill. Compared with observations, the model successfully reproduces the spatial patterns of atmospheric BC and OA concentrations, and agrees with measurements to within a factor of 2. Globally, the simulated AOD agrees well with observations, with a normalized mean bias close to zero. However, the model tends to underestimate AOD over India and China by ∼19±4% but overestimate it over Africa by ∼25±11% (± represents modeled temporal standard deviations for n D 5 run years). Without BC serving as ice nuclei (IN), global and Indian solid fuel cookstove aerosol emissions have net global cooling radiative effects of-141±4mWm-2 and-12±4mWm-2, respectively (± represents modeled temporal standard deviations for n D 5 run years). The net radiative impacts are dominated by the AIE and SDE mechanisms, which originate from enhanced cloud condensation nuclei concentrations for the formation of liquid and mixedphase clouds, and a suppression of convective transport of water vapor from the lower troposphere to the upper troposphere/ lower stratosphere that in turn leads to reduced ice cloud formation. When BC is allowed to behave as a source of IN, the net global radiative impacts of the global and Indian solid fuel cookstove emissions range from-275 to C154mWm-2 and-33 to C24mWm-2, with globally averaged values of-59±215 and 0.3±29mWm-2, respectively. Here, the uncertainty range is based on sensitivity simulations that alter the maximum freezing efficiency of BC across a plausible range: 0.01, 0.05 and 0.1. BC-ice cloud interactions lead to substantial increases in high cloud (<500 hPa) fractions. Thus, the net sign of the impacts of carbonaceous aerosols from solid fuel cookstoves on global climate (warming or cooling) remains ambiguous until improved constraints on BC interactions with mixed-phase and ice clouds are available. © 2018 Copernicus GmbH. All rights reserved."
"25926762100;14045744500;7003582587;7402064802;22635190100;57201123684;7401936984;25629055800;8922308700;55802246600;7102266120;55796504300;8042408300;13006055400;7102425008;6508155070;36187387300;8397494800;7004485409;55713034800;6602504047;8349315600;57001643600;57211721176;56898950300;","CAUSES: Attribution of Surface Radiation Biases in NWP and Climate Models near the U.S. Southern Great Plains",2018,"10.1002/2017JD027188","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044549650&doi=10.1002%2f2017JD027188&partnerID=40&md5=e705c6a25fb5aad93cebef8ba2d6ed85","Many Numerical Weather Prediction (NWP) and climate models exhibit too warm lower tropospheres near the midlatitude continents. The warm bias has been shown to coincide with important surface radiation biases that likely play a critical role in the inception or the growth of the warm bias. This paper presents an attribution study on the net radiation biases in nine model simulations, performed in the framework of the CAUSES project (Clouds Above the United States and Errors at the Surface). Contributions from deficiencies in the surface properties, clouds, water vapor, and aerosols are quantified, using an array of radiation measurement stations near the Atmospheric Radiation Measurement Southern Great Plains site. Furthermore, an in-depth analysis is shown to attribute the radiation errors to specific cloud regimes. The net surface shortwave radiation is overestimated in all models throughout most of the simulation period. Cloud errors are shown to contribute most to this overestimation, although nonnegligible contributions from the surface albedo exist in most models. Missing deep cloud events and/or simulating deep clouds with too weak cloud radiative effects dominate in the cloud-related radiation errors. Some models have compensating errors between excessive occurrence of deep cloud but largely underestimating their radiative effect, while other models miss deep cloud events altogether. Surprisingly, even the latter models tend to produce too much and too frequent afternoon surface precipitation. This suggests that rather than issues with the triggering of deep convection, cloud radiative deficiencies are related to too weak convective cloud detrainment and too large precipitation efficiencies. ©2018 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland."
"56898331700;25227357000;7102018821;57200702127;55717074000;55814053500;7404829395;56537463000;","Type-Dependent Responses of Ice Cloud Properties to Aerosols From Satellite Retrievals",2018,"10.1002/2018GL077261","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045908368&doi=10.1002%2f2018GL077261&partnerID=40&md5=4a4bb62928ac1204299525aa7bfc5b1f","Aerosol-cloud interactions represent one of the largest uncertainties in external forcings on our climate system. Compared with liquid clouds, the observational evidence for the aerosol impact on ice clouds is much more limited and shows conflicting results, partly because the distinct features of different ice cloud and aerosol types were seldom considered. Using 9-year satellite retrievals, we find that, for convection-generated (anvil) ice clouds, cloud optical thickness, cloud thickness, and cloud fraction increase with small-to-moderate aerosol loadings (<0.3 aerosol optical depth) and decrease with further aerosol increase. For in situ formed ice clouds, however, these cloud properties increase monotonically and more sharply with aerosol loadings. An increase in loading of smoke aerosols generally reduces cloud optical thickness of convection-generated ice clouds, while the reverse is true for dust and anthropogenic pollution aerosols. These relationships between different cloud/aerosol types provide valuable constraints on the modeling assessment of aerosol-ice cloud radiative forcing. ©2018. American Geophysical Union. All Rights Reserved."
"7003668116;55915206300;12645767500;36097134700;","An Uncertainty Data Set for Passive Microwave Satellite Observations of Warm Cloud Liquid Water Path",2018,"10.1002/2017JD027638","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045212220&doi=10.1002%2f2017JD027638&partnerID=40&md5=7837dbfd55d560c3319c492cf6b323a8","The first extended comprehensive data set of the retrieval uncertainties in passive microwave observations of cloud liquid water path (CLWP) for warm oceanic clouds has been created for practical use in climate applications. Four major sources of systematic errors were considered over the 9-year record of the Advanced Microwave Scanning Radiometer-EOS (AMSR-E): clear-sky bias, cloud-rain partition (CRP) bias, cloud-fraction-dependent bias, and cloud temperature bias. Errors were estimated using a unique merged AMSR-E/Moderate resolution Imaging Spectroradiometer Level 2 data set as well as observations from the Cloud-Aerosol Lidar with Orthogonal Polarization and the CloudSat Cloud Profiling Radar. To quantify the CRP bias more accurately, a new parameterization was developed to improve the inference of CLWP in warm rain. The cloud-fraction-dependent bias was found to be a combination of the CRP bias, an in-cloud bias, and an adjacent precipitation bias. Globally, the mean net bias was 0.012 kg/m2, dominated by the CRP and in-cloud biases, but with considerable regional and seasonal variation. Good qualitative agreement between a bias-corrected AMSR-E CLWP climatology and ship observations in the Northeast Pacific suggests that the bias estimates are reasonable. However, a possible underestimation of the net bias in certain conditions may be due in part to the crude method used in classifying precipitation, underscoring the need for an independent method of detecting rain in warm clouds. This study demonstrates the importance of combining visible-infrared imager data and passive microwave CLWP observations for estimating uncertainties and improving the accuracy of these observations. ©2018. The Authors."
"57201698175;8953662800;55688847100;55899884100;57206424059;57201700766;56200000400;","The Cloud Top Distribution and Diurnal Variation of Clouds Over East Asia: Preliminary Results From Advanced Himawari Imager",2018,"10.1002/2017JD028044","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045843308&doi=10.1002%2f2017JD028044&partnerID=40&md5=b4110341cca2590526747c7e13ca8cdf","Clouds, as one of the most uncertain factors in climate system, have been intensively studied as satellites with advanced instruments emerged in recent years. However, few studies examine the vertical distributions of cloud top and their temporal variations over East Asia based on geostationary satellite data. In this study, the vertical structures of cloud top and its diurnal variations in summer of 2016 are analyzed using the Advanced Himawari Imager/Himawari-8 cloud products. Results show that clouds occur most frequently over the southern Tibetan Plateau and the Bay of Bengal. We find a steep gradient of cloud occurrence frequency extending from southwest to northeast China and low-value centers over the eastern Pacific and the Inner Mongolia Plateau. The vertical structures of cloud top are highly dependent on latitude, in addition to the nonnegligible roles of both terrain and land-sea thermal contrast. In terms of the diurnal cycle, clouds tend to occur more often in the afternoon, peaking around 1700 local time over land and ocean. The amplitude of cloud diurnal variation over ocean is much smaller than that over land, and complex terrain tends to be linked to larger amplitude. In vertical, the diurnal cycle of cloud frequency exhibits bimodal pattern over both land and ocean. The high-level peaks occur at almost the same altitude over land and ocean. In contrast, the low-level peaks over ocean mainly reside in the boundary layer, much lower than those over land, which could be indicative of the frequent occurrence of marine boundary layer clouds. ©2018. American Geophysical Union. All Rights Reserved."
"56540047500;8578597300;57196169027;6505957129;","Identification of stable areas in unreferenced laser scans for automated geomorphometric monitoring",2018,"10.5194/esurf-6-303-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045571400&doi=10.5194%2fesurf-6-303-2018&partnerID=40&md5=699cee3cac40a72559cab5a4939bd416","Current research questions in the field of geomorphology focus on the impact of climate change on several processes subsequently causing natural hazards. Geodetic deformation measurements are a suitable tool to document such geomorphic mechanisms, e.g. by capturing a region of interest with terrestrial laser scanners which results in a so-called 3-D point cloud. The main problem in deformation monitoring is the transformation of 3-D point clouds captured at different points in time (epochs) into a stable reference coordinate system. In this contribution, a surface-based registration methodology is applied, termed the iterative closest proximity algorithm (ICProx), that solely uses point cloud data as input, similar to the iterative closest point algorithm (ICP). The aim of this study is to automatically classify deformations that occurred at a rock glacier and an ice glacier, as well as in a rockfall area. For every case study, two epochs were processed, while the datasets notably differ in terms of geometric characteristics, distribution and magnitude of deformation. In summary, the ICProx algorithm's classification accuracy is 70 % on average in comparison to reference data. © Author(s) 2018."
"57189986903;55598938800;55885662200;6504572295;7003501766;","The impact of precipitation evaporation on the atmospheric aerosol distribution in EC-Earth v3.2.0",2018,"10.5194/gmd-11-1443-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045583984&doi=10.5194%2fgmd-11-1443-2018&partnerID=40&md5=d1db562e89b6870692a63fa473219d6f","The representation of aerosol-cloud interaction in global climate models (GCMs) remains a large source of uncertainty in climate projections. Due to its complexity, precipitation evaporation is either ignored or taken into account in a simplified manner in GCMs. This research explores various ways to treat aerosol resuspension and determines the possible impact of precipitation evaporation and subsequent aerosol resuspension on global aerosol burdens and distribution. The representation of aerosol wet deposition by large-scale precipitation in the EC-Earth model has been improved by utilising additional precipitation-related 3- D fields from the dynamical core, the Integrated Forecasting System (IFS) general circulation model, in the chemistry and aerosol module Tracer Model, version 5 (TM5). A simple approach of scaling aerosol release with evaporated precipitation fraction leads to an increase in the global aerosol burden (+7.8 to +15% for different aerosol species). However, when taking into account the different sizes and evaporation rate of raindrops following Gong et al. (2006), the release of aerosols is strongly reduced, and the total aerosol burden decreases by -3.0 to -8.5 %. Moreover, inclusion of cloud processing based on observations by Mitra et al. (1992) transforms scavenged small aerosol to coarse particles, which enhances removal by sedimentation and hence leads to a -10 to -11% lower aerosol burden. Finally, when these two effects are combined, the global aerosol burden decreases by -11 to -19 %. Compared to the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations, aerosol optical depth (AOD) is generally underestimated in most parts of the world in all configurations of the TM5 model and although the representation is now physically more realistic, global AOD shows no large improvements in spatial patterns. Similarly, the agreement of the vertical profile with Cloud- Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite measurements does not improve significantly. We show, however, that aerosol resuspension has a considerable impact on the modelled aerosol distribution and needs to be taken into account. © Author(s) 2018."
"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."
"7003341789;36921601500;7404247296;6602516156;56708868600;8791306500;7005453641;8856938500;56499447000;","A climatology of polar stratospheric cloud composition between 2002 and 2012 based on MIPAS/Envisat observations",2018,"10.5194/acp-18-5089-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045558230&doi=10.5194%2facp-18-5089-2018&partnerID=40&md5=071de1b50e8a3596ba79b4d20cba6a1c","The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument aboard the European Space Agency (ESA) Envisat satellite operated from July 2002 to April 2012. The infrared limb emission measurements provide a unique dataset of day and night observations of polar stratospheric clouds (PSCs) up to both poles. A recent classification method for PSC types in infrared (IR) limb spectra using spectral measurements in different atmospheric window regions has been applied to the complete mission period of MIPAS. The method uses a simple probabilistic classifier based on Bayes' theorem with a strong independence assumption on a combination of a well-established two-colour ratio method and multiple 2-D probability density functions of brightness temperature differences. The Bayesian classifier distinguishes between solid particles of ice, nitric acid trihydrate (NAT), and liquid droplets of supercooled ternary solution (STS), as well as mixed types. A climatology of MIPAS PSC occurrence and specific PSC classes has been compiled. Comparisons with results from the classification scheme of the spaceborne lidar Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol-Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite show excellent correspondence in the spatial and temporal evolution for the area of PSC coverage (APSC) even for each PSC class. Probability density functions of the PSC temperature, retrieved for each class with respect to equilibrium temperature of ice and based on coincident temperatures from meteorological reanalyses, are in accordance with the microphysical knowledge of the formation processes with respect to temperature for all three PSC types. This paper represents unprecedented pole-covering day- and nighttime climatology of the PSC distributions and their composition of different particle types. The dataset allows analyses on the temporal and spatial development of the PSC formation process over multiple winters. At first view, a more general comparison of APSC and AICE retrieved from the observations and from the existence temperature for NAT and ice particles based on the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis temperature data shows the high potential of the climatology for the validation and improvement of PSC schemes in chemical transport and chemistry-climate models. © 2018 Lippincott Williams and Wilkins. All rights reserved."
"56989640500;21935606200;55802246600;56537237200;7202048112;","Aerosol and Urban Land Use Effect on Rainfall Around Cities in Indo-Gangetic Basin From Observations and Cloud Resolving Model Simulations",2018,"10.1002/2017JD028004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045181839&doi=10.1002%2f2017JD028004&partnerID=40&md5=2ab2e584b701b37d2f8985eb837e5ef7","Coupling of urban land use land cover (LULC) and aerosol loading on rainfall around cities in the Gangetic Basin (GB) is examined here. Long-term observations illustrate more rainfall at urban core and climatological downwind regions compared to the upwind regions of Kanpur, a metropolitan area located in central GB. In addition, analysis of a 15 day cloud resolving simulation using the Weather Research and Forecasting model also illustrated similar rainfall pattern around other major cities in the GB. Interestingly, the enhancement of downwind rainfall was greater than that over urban regions, and it was positively associated with both the urban area of the city and ambient aerosol loading during the propagating storm. Further, to gain a process-level understanding, a typical storm that propagated northwestward across Kanpur was simulated using Weather Research and Forecasting under three different scenarios. Case 1 has realistic LULC representation of Kanpur, while the grids representing the Kanpur urban region were replaced by cropland LULC pattern in Case 2. Comparison illustrated that urban heat island effect caused convergence of winds and moisture in the lower troposphere, which enhances convection over urban region and induced more rainfall over the urban core compared to upwind regions. Case 3 is similar to Case 1 but lower aerosol concentration (by a factor of 100) over the storm region. Analysis shows that aerosol-induced microphysical changes delay the initiation of warm rain (over the upwind region) but enhance ice phase particle formation in latter stages (over the urban and downwind regions) resulting in increase in downwind rainfall. ©2018. American Geophysical Union. All Rights Reserved."
"55994734800;57133112900;6603748992;","Coastal low cloudiness and fog enhance crop water use efficiency in a California agricultural system",2018,"10.1016/j.agrformet.2018.01.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041470658&doi=10.1016%2fj.agrformet.2018.01.015&partnerID=40&md5=36bae413fdffa29a4d31882224def39c","Impacts of climate change threaten California farmers in a number of ways, most importantly through a decline in freshwater availability, concurrent with a rise in water demand. In coastal California, the growing season of economically important crops, such as strawberries, overlap with the occurrence of summertime coastal fog, which buffers the summer dry season through shading effects and direct water inputs. The impacts of coastal fog on plant physiology have been extensively studied in natural ecosystems. Yet, very few studies have evaluated its direct effects on crop water use and demand, which has potential to curtail groundwater use. We established two sites on large, conventional strawberry farms along a coastal-inland gradient in the Salinas Valley, California, where we monitored variation in microclimate conditions and measured strawberry plant physiological responses to foggy and non-foggy conditions between June–September 2015. Spatial analysis of coastal low clouds and fog from satellite imagery was preformed to quantify and characterize fog events at seasonal and diel time scales. We found strong agreement between field and satellite-derived observations of coastal fog events. Canopy-level conductance and whole-plant carbon uptake were reduced by 60% and 30%, respectively, on foggy compared to clear-sky days. Leaf-level photosynthesis and stomatal conductance were 30% lower on foggy compared to clear-sky days, which was driven by reduced photosynthetically active radiation and cooler temperatures during fog events. Taken together, we found that whole-plant water use efficiency increased significantly during foggy periods, and these patterns were driven by changes in the radiation balance and atmospheric water stress. Our results provide evidence that the shading effect by fog is a primary influence on crop water use efficiency in coastal agricultural fields during summer. The outcome of our research can inform estimates of how much irrigation water may be reduced during foggy periods without sacrificing crop yields on coastal agricultural lands. © 2018 Elsevier B.V."
"57192915106;55938109300;7006770362;54941580100;12544502800;55879681300;13007286600;55807448700;56998535300;57196082964;24767977600;22635720500;7003862871;24333054700;6505947323;7004020627;9738422100;39361670300;","An assessment of aerosol optical properties from remote-sensing observations and regional chemistry-climate coupled models over Europe",2018,"10.5194/acp-18-5021-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045392738&doi=10.5194%2facp-18-5021-2018&partnerID=40&md5=cfc2b2982732b0f7e1e498ffcf454f3e","Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical and chemical properties, and are considered one of the most uncertain climate forcing agents. In order to characterise the uncertainties associated with satellite and modelling approaches to represent aerosol optical properties, mainly aerosol optical depth (AOD) and Ångström exponent (AE), their representation by different remote-sensing sensors and regional online coupled chemistry-climate models over Europe are evaluated. This work also characterises whether the inclusion of aerosol-radiation (ARI) or/and aerosol-cloud interactions (ACI) help improve the skills of modelling outputs. Two case studies were selected within the EuMetChem COST Action ES1004 framework when important aerosol episodes in 2010 all over Europe took place: a Russian wildfire episode and a Saharan desert dust outbreak that covered most of the Mediterranean Sea. The model data came from different regional air-quality-climate simulations performed by working group 2 of EuMetChem, which differed according to whether ARI or ACI was included or not. The remote-sensing data came from three different sensors: MODIS, OMI and SeaWIFS. The evaluation used classical statistical metrics to first compare satellite data versus the ground-based instrument network (AERONET) and then to evaluate model versus the observational data (both satellite and ground-based data). Regarding the uncertainty in the satellite representation of AOD, MODIS presented the best agreement with the AERONET observations compared to other satellite AOD observations. The differences found between remote-sensing sensors highlighted the uncertainty in the observations, which have to be taken into account when evaluating models. When modelling results were considered, a common trend for underestimating high AOD levels was observed. For the AE, models tended to underestimate its variability, except when considering a sectional approach in the aerosol representation. The modelling results showed better skills when ARI+ACI interactions were included; hence this improvement in the representation of AOD (above 30 % in the model error) and AE (between 20 and 75 %) is important to provide a better description of aerosol-radiation-cloud interactions in regional climate models. © 2018 Copernicus GmbH. All rights reserved."
"57194876603;57203030873;","The influence of extratropical cloud phase and amount feedbacks on climate sensitivity",2018,"10.1007/s00382-017-3796-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023776541&doi=10.1007%2fs00382-017-3796-5&partnerID=40&md5=62340bc0a1e82da635ab262c9f4de75a","Global coupled climate models have large long-standing cloud and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled cloud liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-layer ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave cloud feedbacks. First, reduced conversion of cloud ice to liquid at high southern latitudes decreases the magnitude of a negative cloud phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave cloud feedback. The positive cloud feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary layer and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary layer, which decreases cloud amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive cloud feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase cloud partitioning, cloud feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes. © 2017, Springer-Verlag GmbH Germany."
"54399869900;7401836526;","Atmospheric dynamics feedback: Concept, simulations, and climate implications",2018,"10.1175/JCLI-D-17-0470.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042849303&doi=10.1175%2fJCLI-D-17-0470.1&partnerID=40&md5=6c8bf7b48ce659940c21bc7aa8229481","The regional climate response to radiative forcing is largely controlled by changes in the atmospheric circulation. It has been suggested that global climate sensitivity also depends on the circulation response, an effect called the ""atmospheric dynamics feedback."" Using a technique to isolate the influence of changes in atmospheric circulation on top-of-the-atmosphere radiation, the authors calculate the atmospheric dynamics feedback in coupled climate models. Large-scale circulation changes contribute substantially to all-sky and cloud feedbacks in the tropics but are relatively less important at higher latitudes. Globally averaged, the atmospheric dynamics feedback is positive and amplifies the near-surface temperature response to climate change by an average of 8% in simulations with coupled models. A constraint related to the atmospheric mass budget results in the dynamics feedback being small on large scales relative to feedbacks associated with thermodynamic processes. Idealized-forcing simulations suggest that circulation changes at high latitudes are potentially more effective at influencing global temperature than circulation changes at low latitudes, and the implications for past and future climate change are discussed. © 2018 American Meteorological Society."
"55688930000;37099564300;15755995900;57193213111;7006705919;","Using the Atmospheric Radiation Measurement (ARM) datasets to evaluate climate models in simulating diurnal and seasonal variations of tropical clouds",2018,"10.1175/JCLI-D-17-0362.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047090405&doi=10.1175%2fJCLI-D-17-0362.1&partnerID=40&md5=7d61925beb346463d5be3dc9b5db6f89","Long-term Atmospheric Radiation Measurement (ARM) datasets collected at the three tropical western Pacific (TWP) sites are used to evaluate the ability of the Community Atmosphere Model (CAM5) to simulate the various types of clouds, their seasonal and diurnal variations, and their impact on surface radiation. A number of CAM5 simulations are conducted at various horizontal grid spacing (around 2°, 1°, 0.5°, and 0.25°) with meteorological constraints from analysis or reanalysis. Model biases in the seasonal cycle of cloudiness are found to be weakly dependent on model resolution. Positive biases (up to 20%) in the annual mean total cloud fraction appear mostly in stratiform ice clouds. Higher-resolution simulations do reduce the positive bias in ice clouds, but they inadvertently increase the negative biases in convective clouds and low-level liquid clouds, leading to a positive bias in annual mean shortwave fluxes at the sites, as high as 65 W m-2 in the 0.25° simulation. Such resolution-dependent biases in clouds can adversely lead to biases in ambient thermodynamic properties and, in turn, produce feedback onto clouds. Both the model and observations show distinct diurnal cycles in total, stratiform, and convective cloud fractions; however, they are out of phase by 12 h and the biases vary by site. The results suggest that biases in deep convection affect the vertical distribution and diurnal cycle of stratiform clouds through the transport of vapor and/or the detrainment of liquid and ice. The approach used here can be easily adapted for the evaluation of new parameterizations being developed for CAM5 or other global or regional models. © 2018 American Meteorological Society."
"35098162000;37058739000;56612951100;56047308100;","Effect of cloud fraction on arctic low-level temperature inversions in AIRS observations over both land and ocean",2018,"10.1109/TGRS.2017.2772297","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037657743&doi=10.1109%2fTGRS.2017.2772297&partnerID=40&md5=13dbc319382fd928f06e7f8ad0dbac66","The low-level temperature inversions have significant impacts on Arctic climate change feedbacks. The Atmospheric Infrared Sounder (AIRS) can extract the inversions over both land and ocean, and it is, however, sensitive to the presence of clouds. In this paper, we evaluate the effect of cloud fraction (CF) on AIRS inversions over both land and ocean. First, the AIRS inversions under clear-sky conditions are compared with the results from the microwave-based Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations in 2007-2013. Results show that despite the COSMIC and AIRS inversions appearing to be deeper and stronger in winter than in autumn, spring, and summer, the former is generally shallower and stronger than the latter in all seasons over both land and ocean. Time-series analysis of the mean monthly inversions from COSMIC and AIRS observations in 2007-2013 under both clear-sky and cloudy conditions further indicates that their differences are systematic and can be effectively mitigated after calibration under all sky conditions. Taking the calibrated COSMIC inversions as references, the AIRS inversion depths can be estimated with a root mean square (rms) of less than about 86 and 135 m, and the AIRS inversion strength can be obtained with an rms of better than about 1.7 °C and 1.3 °C under cloudy conditions over land and ocean, respectively. Moreover, while the AIRS inversion depths are insensitive to CF variations over both land and ocean, the inversion strengths are more sensitive to the CF variations over land than ocean. © 1980-2012 IEEE."
"56900300700;36627352900;35209683700;7408519295;7404829395;55814053500;16197778800;","Dynamical and thermodynamical coupling between the North Atlantic subtropical high and the marine boundary layer clouds in boreal summer",2018,"10.1007/s00382-017-3750-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020668018&doi=10.1007%2fs00382-017-3750-6&partnerID=40&md5=e15de9a9f9c823ea192dd8cf418b50a3","This study investigates dynamical and thermodynamical coupling between the North Atlantic subtropical high (NASH), marine boundary layer (MBL) clouds, and the local sea surface temperatures (SSTs) over the North Atlantic in boreal summer for 1984–2009 using NCEP/DOE Reanalysis 2 dataset, various cloud data, and the Hadley Centre sea surface temperature. On interannual timescales, the summer mean subtropical MBL clouds to the southeast of the NASH is actively coupled with the NASH and local SSTs: a stronger (weaker) NASH is often accompanied with an increase (a decrease) of MBL clouds and abnormally cooler (warmer) SSTs along the southeast flank of the NASH. To understand the physical processes between the NASH and the MBL clouds, the authors conduct a data diagnostic analysis and implement a numerical modeling investigation using an idealized anomalous atmospheric general circulation model (AGCM). Results suggest that significant northeasterly anomalies in the southeast flank of the NASH associated with an intensified NASH tend to induce stronger cold advection and coastal upwelling in the MBL cloud region, reducing the boundary surface temperature. Meanwhile, warm advection associated with the easterly anomalies from the African continent leads to warming over the MBL cloud region at 700 hPa. Such warming and the surface cooling increase the atmospheric static stability, favoring growth of the MBL clouds. The anomalous diabatic cooling associated with the growth of the MBL clouds dynamically excites an anomalous anticyclone to its north and contributes to strengthening of the NASH circulation in its southeast flank. The dynamical and thermodynamical couplings and their associated variations in the NASH, MBL clouds, and SSTs constitute an important aspect of the summer climate variability over the North Atlantic. © 2017, Springer-Verlag GmbH Germany."
"57193418162;56471429200;7003975505;","The role of sea-ice albedo in the climate of slowly rotating aquaplanets",2018,"10.1007/s00382-017-3548-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013757357&doi=10.1007%2fs00382-017-3548-6&partnerID=40&md5=dc9acc4be7d2c8258c4850ae229341e1","We investigate the influence of the rotation period (P rot) on the mean climate of an aquaplanet, with a focus on the role of sea-ice albedo. We perform aquaplanet simulations with the atmospheric general circulation model ECHAM6 for various rotation periods from one Earth-day to 365 Earth-days in which case the planet is synchronously rotating. The global-mean surface temperature decreases with increasing P rot and sea ice expands equatorwards. The cooling of the mean climate with increasing P rot is caused partly by the high surface albedo of sea ice on the dayside and partly by the high albedo of the deep convective clouds over the substellar region. The cooling caused by these deep convective clouds is weak for non-synchronous rotations compared to synchronous rotation. Sensitivity simulations with the sea-ice model switched off show that the global-mean surface temperature is up to 27 K higher than in our main simulations with sea ice and thus highlight the large influence of sea ice on the climate. We present the first estimates of the influence of the rotation period on the transition of an Earth-like climate to global glaciation. Our results suggest that global glaciation of planets with synchronous rotation occurs at substantially lower incoming solar irradiation than for planets with slow but non-synchronous rotation. © 2017, The Author(s)."
"15047538100;15050523700;6602135370;57193612001;36242447900;23969692000;","SST and OLR relationship during Indian summer monsoon: a coupled climate modelling perspective",2018,"10.1007/s00703-017-0514-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015217101&doi=10.1007%2fs00703-017-0514-0&partnerID=40&md5=50b02a606cde72d7e19d1450d7da5a3c","The study mainly investigates sea surface temperature (SST) and outgoing longwave radiation (OLR) relationships in coupled climate model. To support the analysis, high-level cloud and OLR relationship is also investigated. High-level cloud and OLR relationship depicts significant negative correlation over the entire monsoon regime. Coupled climate model is able to produce the same. SST and OLR relationship in observation also depicts significant negative relationship, in particular, over the Equatorial Eastern Indian Ocean (EIO) region. Climate Forecast System version 2 (CFSv2) is able to portray the negative relationship over EIO region; however, it is underestimated as compared to observation. Significant negative correlations elucidate that local SSTs regulate the convection and further it initiates Bjerknes feedback in the central Indian Ocean. It connotes that SST anomalies during monsoon period tend to be determined by oceanic forcing. The heat content of the coastal Bay of Bengal shows highest response to EIO SST by a lag of 1 month. It suggests that the coastal region of the Bay of Bengal is marked by coastally trapped Kelvin waves, which might have come from EIO at a time lag of 1 month. Sea surface height anomalies, depth at 20 °C isotherms and depth at 26 isotherms also supports the above hypothesis. Composite analysis based on EIO index and coupled climate model sensitivity experiments also suggest that the coastal Bay of Bengal region is marked by coastally trapped Kelvin waves, which are propagated from EIO at a time lag of 1 month. Thus, SST and OLR relationship pinpoints that the Bay of Bengal OLR (convection) is governed by local ocean–atmospheric coupling, which is influenced by the delayed response from EIO brought forward through oceanic planetary waves at a lag of 1 month. These results have utmost predictive value for seasonal and extended range forecasting. Thus, OLR and SST relationship can constitute a pivotal role in investigating the atmosphere–ocean interaction. © 2017, Springer-Verlag Wien."
"36448166800;56958366900;57200306636;57213583761;","Toward ecologically realistic predictions of species distributions: A cross-time example from tropical montane cloud forests",2018,"10.1111/gcb.13992","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042591831&doi=10.1111%2fgcb.13992&partnerID=40&md5=a7a7a396f572e05c16eece562f9df9f1","There is an urgent need for more ecologically realistic models for better predicting the effects of climate change on species’ potential geographic distributions. Here we build ecological niche models using MAXENT and test whether selecting predictor variables based on biological knowledge and selecting ecologically realistic response curves can improve cross-time distributional predictions. We also evaluate how the method chosen for extrapolation into nonanalog conditions affects the prediction. We do so by estimating the potential distribution of a montane shrew (Mammalia, Soricidae, Cryptotis mexicanus) at present and the Last Glacial Maximum (LGM). Because it is tightly associated with cloud forests (with climatically determined upper and lower limits) whose distributional shifts are well characterized, this species provides clear expectations of plausible vs. implausible results. Response curves for the MAXENT model made using variables selected via biological justification were ecologically more realistic compared with those of the model made using many potential predictors. This strategy also led to much more plausible geographic predictions for upper and lower elevational limits of the species both for the present and during the LGM. By inspecting the modeled response curves, we also determined the most appropriate way to extrapolate into nonanalog environments, a previously overlooked factor in studies involving model transfer. This study provides intuitive context for recommendations that should promote more realistic ecological niche models for transfer across space and time. © 2017 John Wiley & Sons Ltd"
"36480719700;57200423032;57200419851;57200422466;57200410028;","Characteristics of cloud-to-ground lightning and its relationship with climate change in Muli, Sichuan province, China",2018,"10.1007/s11069-018-3169-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041197108&doi=10.1007%2fs11069-018-3169-3&partnerID=40&md5=d9cda31c714a6053ef2def3eb716e066","Along with climate change, cloud-to-ground lightning (CG)-caused forest fires are becoming increasingly pronounced. This study employed the Chinese lightning location system data (2009–2015) and worldwide lightning location network data (2005–2015) to jointly analyze CG characteristics and study the correlation between CG and climate change. The Muli county in southwest China was taken as research area. The CG number showed a clear increasing trend on yearly timescale. At the monthly timescale, CG occurred from March to October, with a peak in June. At the daily timescale, 15:00–23:00 (local time) and 00:00–05:00 both had a high CG frequency, and the peak was at 18:00–19:00. We divided CG electric current intensity into six grades and found that negative CG accounted for more than 90% of total CG and, among these, the 3rd and 4th intensity grades accounted for about 70%. To examine the spatial distribution, we focused on lightning-caused forest fires high occurrence seasons. In spring, CG distribution changed from the initial southeast to the northwest, gradually spreading to the whole area of Muli, whereas the CG area gradually moved back to the southeast in autumn. Our research suggested that minimum temperature was the most sensitive temperature to CG change. In March, the relationship between CG and minimum temperature showed a strong positive correlation. Considered jointly, we suggest the CG and related lightning-caused forest fires could increase in the future under an increased minimum temperature and decreased precipitation, especially in March. © 2018, The Author(s)."
"57202161629;30867530400;7402934750;","The occurrence and properties of long-lived liquid-bearing clouds over the greenland ice sheet and their relationship to the North Atlantic Oscillation",2018,"10.1175/JAMC-D-17-0230.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045220596&doi=10.1175%2fJAMC-D-17-0230.1&partnerID=40&md5=405762b36248c8eedef0002e8de891bd","Stratiform liquid-bearing clouds (LBCs), defined herein as either pure liquid or mixed-phase clouds, have a large impact on the surface radiation budget across the Arctic. LBCs lasting at least 6 h are observed at Summit, Greenland, year-round with a maximum in occurrence during summer. Mean cloud-base height is below 1 km for 85% of LBC cases identified, 59% have mean liquid water path (LWP) values between 10 and 40 gm-2, and most produce sporadic light ice-phase precipitation. During their occurrence, the atmosphere above the ice sheet is anomalously warm and moist, with southerly winds observed over much of the ice sheet, including at Summit. LBCs that occur when the North Atlantic Oscillation (NAO) is in the negative phase correspond to strong ridging centered over the Greenland Ice Sheet (GIS), allowing for southwesterly flow over the GIS toward Summit. During the positive phase of the NAO, the occurrence of LBCs corresponds to a cyclone located off the southeastern coast of the ice sheet, which leads to easterly-to-southeasterly flow toward Summit. Furthermore, air parcels at Summit frequently originate from below the elevation of Summit, indicating that orographic lift along the ice sheet is a factor in the occurrence of LBCs at Summit. LBCs are more frequently observed during the negative NAO, and both the LWP and precipitation rate are larger in LBCs occurring during this phase. Mean LWP in LBCs occurring during the negative NAO is 15 gm-2 larger than in LBCs occurring during the positive phase. © 2018 American Meteorological Society."
"56085419300;7005632987;","Influence of aerosol-cloud interaction on austral summer precipitation over Southern Africa during ENSO events",2018,"10.1016/j.atmosres.2017.11.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033585917&doi=10.1016%2fj.atmosres.2017.11.011&partnerID=40&md5=ea873c4f1e77a27f6262322eab02056b","In the present study, we are investigating the role of aerosols-and clouds in modulating the austral summer precipitation (December–February) during ENSO events over southern Africa region for the period from 2002 to2012 by using satellite and complimentary data sets. Aerosol radiative forcing (ARF) and Cloud radiative forcing (CRF) shows distinct patterns for El-Nina and La-Nina years. Further analysis were carried out by selecting the four Southern Africa regions where the precipitation shows remarkable difference during El-Nino and La-Nina years. These regions are R1 (33°S–24°S, 18°E–30°E), R2 (17°S–10°S, 24°E–32°E), R3 (19°S–9°S, 33°E–41°E) and R4 (7°S–0°S, 27°E–36°E). Aerosol Optical depth (AOD) shows considerable differences during these events. In region R1, R2 and R3 AOD shows more abundance in El-Nino years as compared to La-Nina years where as in R4 the AOD shows more abundance in La-Nina years. Cloud Droplet Effective radius (CDER) shows higher values during La-Nina years over R1, R2 and R3 regions but in R4 region CDER shows higher values in El-Nino years. Aerosol indirect effect (AIE) is estimated both for fixed cloud liquid water path (CLWP) and for fixed cloud ice path (CIP) bins, ranging from 1 to 300 gm –2 at 25 gm –2 interval over all the selected regions for El-Nino and La-Nina years. The results indicate more influence of positive indirect effect (Twomey effect) over R1 and R3 region during El-Nino years as compared to La-Nina years. This analysis reveals the important role of aerosol on cloud-precipitation interaction mechanism illustrating the interlinkage between dynamics and microphysics during austral summer season over southern Africa. © 2017 Elsevier B.V."
"7410070663;25941200000;","Computation of domain-average radiative flux profiles using Gaussian quadrature",2018,"10.1002/qj.3241","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052533538&doi=10.1002%2fqj.3241&partnerID=40&md5=170387d5c2db1c6eee42fb3992473e27","A method for calculating domain-average radiative flux profiles, called Gaussian Quadrature Independent Column Approximation (GQ-ICA), is introduced and assessed using cloud properties retrieved from A-Train satellite data. This method could be suitable for use in large-scale atmospheric models. Like the Monte Carlo ICA (McICA), GQ-ICA uses N stochastically generated subgrid-scale cloudy columns. The independent variable is the sorted, from smallest to largest, sequence of N sub-column values of liquid and ice cloud water paths. The integrand is essentially the radiative transfer equation. Accurate GQ integration requires integrands to be relatively smooth functions. Unlike McICA, GQ-ICA performs full solar and infrared spectral integrations on nG < < N sub-columns which are identified by rules governing nG-node GQ. The nG flux profiles are appropriately weighted and summed to give domain averages. Several sorting procedures were considered, and all results are based on the CCCma radiation algorithm. For solar radiation, 1-node GQ-ICA can produce significant bias errors, but its random errors are generally less than McICA's. These biases, however, are almost eliminated by 2-node GQ-ICA. For GQ-ICA to better McICA's random errors for infrared fluxes, at least the 2-node version is needed. Ultimately, 2-node GQ-ICA random errors for net fluxes at surface and top-of-atmosphere are typically 30–50% of McICA's. This is partly because solar and infrared solvers operate on the same sub-columns. GQ-ICA random errors for atmospheric heating rates are comparable to McICA's even for 3-node GQ-ICA. Computational times required for the 2- and 3-node GQ-ICA are, respectively, ∼180 and ∼230% of McICA's. © 2018 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"7409788341;7201443624;","Unrealistic increases in wind speed explain reduced Eastern Pacific heat flux in reanalyses",2018,"10.1175/JCLI-D-17-0642.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047067202&doi=10.1175%2fJCLI-D-17-0642.1&partnerID=40&md5=10c8b517924a89e664e44e55417f8109","Tropical eastern Pacific sea surface temperature plays a pivotal role in mechanisms that determine global mean surface temperature variability. In this study, the surface flux contribution to recent cooling of the tropical eastern Pacific is investigated using data from three atmospheric reanalyses with full assimilation of observations, an observation-based net surface energy flux reconstruction, and 15 atmosphere-only climate model simulations. For ERA-Interim, 78% of the decrease in net surface flux (-0.65 W m-2 yr-1 over 1988-2008) is explained by the latent heat flux variability. Latent heat flux variability differs between datasets, and this is investigated using a bulk formula. It is found that discrepancies in wind speed change explain contrasting latent heat flux trends across datasets. The significant increase in wind speed of 0.26 m s-1 decade-1 over the tropical eastern Pacific in ERA-Interim is not reproduced by satellite or buoy observations or atmosphere-only climate model simulations, casting questions on the reliability of reanalysis-based surface fluxes over the tropical eastern Pacific. © 2018 American Meteorological Society."
"36494729400;8720083500;6701363731;7003286544;35191486300;","Impact of Tropospheric Ozone on Summer Climate in China",2018,"10.1007/s13351-018-7094-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046664171&doi=10.1007%2fs13351-018-7094-x&partnerID=40&md5=05856320d4a0d966deb634c0499782f1","The spatial distribution, radiative forcing, and climatic effects of tropospheric ozone in China during summer were investigated by using the regional climate model RegCM4. The results revealed that the tropospheric ozone column concentration was high in East China, Central China, North China, and the Sichuan basin during summer. The increase in tropospheric ozone levels since the industrialization era produced clear-sky shortwave and clear-sky longwave radiative forcing of 0.18 and 0.71 W m–2, respectively, which increased the average surface air temperature by 0.06 K and the average precipitation by 0.22 mm day–1 over eastern China during summer. In addition, tropospheric ozone increased the land–sea thermal contrast, leading to an enhancement of East Asian summer monsoon circulation over southern China and a weakening over northern China. The notable increase in surface air temperature in northwestern China, East China, and North China could be attributed to the absorption of longwave radiation by ozone, negative cloud amount anomaly, and corresponding positive shortwave radiation anomaly. There was a substantial increase in precipitation in the middle and lower reaches of the Yangtze River. It was related to the enhanced upward motion and the increased water vapor brought by strengthened southerly winds in the lower troposphere. © 2018, The Chinese Meteorological Society and Springer-Verlag GmbH Germany, part of Springer Nature."
"56050004200;8530104100;12753475500;","Higher absorbed solar radiation partly offset the negative effects of water stress on the photosynthesis of Amazon forests during the 2015 drought",2018,"10.1088/1748-9326/aab0b1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047748506&doi=10.1088%2f1748-9326%2faab0b1&partnerID=40&md5=963e585977c705e97bb3d2e4623495ae","Amazon forests play an important role in the global carbon cycle and Earth's climate. The vulnerability of Amazon forests to drought remains highly controversial. Here we examine the impacts of the 2015 drought on the photosynthesis of Amazon forests to understand how solar radiation and precipitation jointly control forest photosynthesis during the severe drought. We use a variety of gridded vegetation and climate datasets, including solar-induced chlorophyll fluorescence (SIF), photosynthetic active radiation (PAR), the fraction of absorbed PAR (APAR), leaf area index (LAI), precipitation, soil moisture, cloud cover, and vapor pressure deficit (VPD) in our analysis. Satellite-derived SIF observations provide a direct diagnosis of plant photosynthesis from space. The decomposition of SIF to SIF yield (SIFyield) and APAR (the product of PAR and fPAR) reveals the relative effects of precipitation and solar radiation on photosynthesis. We found that the drought significantly reduced SIFyield, the emitted SIF per photon absorbed. The higher APAR resulting from lower cloud cover and higher LAI partly offset the negative effects of water stress on the photosynthesis of Amazon forests, leading to a smaller reduction in SIF than in SIFyield and precipitation. We further found that SIFyield anomalies were more sensitive to precipitation and VPD anomalies in the southern regions of the Amazon than in the central and northern regions. Our findings shed light on the relative and combined effects of precipitation and solar radiation on photosynthesis, and can improve our understanding of the responses of Amazon forests to drought. © 2018 The Author(s). Published by IOP Publishing Ltd."
"57197761206;55544443300;57202073722;35423103700;7201785152;","Contrasting local and remote impacts of surface heating on polar warming and amplification",2018,"10.1175/JCLI-D-17-0600.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047063232&doi=10.1175%2fJCLI-D-17-0600.1&partnerID=40&md5=0b5850a2aa32831960935c1a00235b6c","The polar region has been one of the fastest warming places on Earth in response to greenhouse gas (GHG) forcing. Two distinct processes contribute to the observed warming signal: (i) local warming in direct response to the GHG forcing and (ii) the effect of enhanced poleward heat transport from low latitudes. A series of aquaplanet experiments, which excludes the surface albedo feedback, is conducted to quantify the relative contributions of these two physical processes to the polar warming magnitude and degree of amplification relative to the global mean. The globe is divided into zonal bands with equal area in eight experiments. For each of these, an external heating is prescribed beneath the slab ocean layer in the respective forcing bands. The summation of the individual temperature responses to each local heating in these experiments is very similar to the response to a globally uniform heating. This allows the authors to decompose the polar warming and amplification signal into the effects of local and remote heating. Local polar heating that induces surface-trapped warming due to the large tropospheric static stability in this region accounts for about half of the polar surface warming. Cloud radiative effects act to enhance this local contribution. In contrast, remote nonpolar heating induces a robust polar warming pattern that features a midtropospheric peak, regardless of the meridional location of the forcing. Among all remote forcing experiments, the deep tropical forcing case contributes most to the polar-amplified surface warming pattern relative to the global mean, while the high-latitude forcing cases contribute most to enhancing the polar surface warming magnitude. © 2018 American Meteorological Society."
"57194113949;57205342499;57201725986;57194116803;","Differences in precipitation efficiency and their probable mechanisms between the warm sector and cold front stages of a heavy rainfall event over Beijing",2018,"10.1002/asl.802","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045911032&doi=10.1002%2fasl.802&partnerID=40&md5=b1b0066c9b9d020e1aaa967c55ebee3e","A heavy rainfall event that occurred in Beijing on July 21, 2012 was simulated successfully using the Weather Research and Forecasting model, and the precipitation efficiency (PE) during different rainfall stages was studied. The results showed that both the large-scale precipitation efficiency (LSPE) and the cloud-microphysics precipitation efficiency (CMPE) in the peak of the warm sector stage (T1) were significantly higher than those in the cold front stage (T2). The higher LSPE was related to the water vapor advection, which played a positive role in T1 due to the warm and moist advection in the lower troposphere, and a negative role in T2 because of the cold and dry airflow in the middle level. The snow-related microphysical processes had similar tendencies to the CMPE, in which the higher rain–snow collection and deposition of water vapor brought about the higher CMPE in T1. Analysis of the underlying mechanisms proved that the LSPE and CMPE were subject to the large-scale environment and cloud microphysical features. © 2018 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"6602135370;15050523700;36242447900;15047538100;57200444123;6507979420;9942293700;","Contrast in monsoon precipitation over oceanic region of north Bay of Bengal and east equatorial Indian Ocean",2018,"10.1002/joc.5433","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041286487&doi=10.1002%2fjoc.5433&partnerID=40&md5=4333d47aa1b747432dc3e67298817ef5","This study explores the possible causes of rainfall distribution over the two major oceanic raining regions of the north Bay of Bengal (nBoB) and the east equatorial Indian Ocean (eEIO). Despite 17% difference in vertically averaged humidity, there is almost 34% difference in mean rainfall over these two regions. The climatological seasonal [June–September (JJAS)] mean (standard deviation) rainfall over nBoB region is always higher (lower) than that over the eEIO region in all the independent data used. The eEIO region has a much larger percentage of low stratiform and convective rainfall (<5 mm day−1) distribution as compared to nBoB, which is totally opposite in case of moderate stratiform and convective rainfall (>5 mm day−1) distribution. This is further substantiated by a much lower values of outgoing long-wave radiation (OLR) in nBoB (<200 W m−2) as compared to the eEIO (217 W m−2) region. Mean Hadley circulation along with relative vorticity/divergence profile supports more intense (gentle) updrafts over nBoB (eEIO) region. Latent heat (LH) is almost three times at the upper level (∼8 km) in case of nBoB as compared to eEIO; however, at the lower level (∼3 km) LH is marginally higher over eEIO region. Microphysical variables, namely cloud ice optical thickness and cloud ice water path, are in much larger quantities over nBoB as compared to eEIO. Furthermore, the cold (warm) rain processes dominate among other microphysical processes over nBoB (eEIO) region. Thus, the interplay among large-scale dynamics, thermodynamics and microphysics is very crucial in the formation of deep clouds and convective rain over the nBoB region and similarly shallow clouds and stratiform rain over the eEIO region. This study will be very useful to guide present-day coupled models for proper representation of different rain components over the nBoB and eEIO region. © 2018 Royal Meteorological Society"
"57188767737;8953662800;56183114900;7402944490;36810780500;55838270500;57202080890;55899884100;","Large-scale pattern of the diurnal temperature range changes over East Asia and Australia in boreal winter: A perspective of atmospheric circulation",2018,"10.1175/JCLI-D-17-0608.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047097609&doi=10.1175%2fJCLI-D-17-0608.1&partnerID=40&md5=e2007e9bec51e421671c2c10ce3e67c5","The present study applies the empirical orthogonal function (EOF) method to investigate the large-scale pattern and the plausible dynamic processes of the boreal winter diurnal temperature range (DTR) changes in the East Asia (EA)-Australia (AUS) region based on the CRU Time Series version 4.00 (TS4.00) and NCEP-NCAR reanalysis datasets. Results show that the DTR changes during 1948-2015 are dominated by two distinct modes. The first mode, characterized by a same-sign variation over most regions of EA-AUS, represents a declining trend of DTR. The second mode, featuring an opposite-sign variation, represents the interannual variations in DTR. The two modes are both closely associated with the changes in cloud cover (CLT) caused by atmospheric circulation anomalies in EA-AUS. For the trend mode, anomalous southerly and northerly winds over EA and AUS, respectively, bring warm and wet air from low latitudes to EA-AUS, inducing an increase in CLT and thereby reducing DTR in most areas of EA-AUS. The changes of circulation are mainly due to the thermodynamic responses of atmosphere to the nonuniform warming in EA-AUS. In addition, the second mode of DTR is largely forced by the ENSO variability. The weakened Walker circulation associated with warm ENSO events triggers a pair of anomalous low-level anticyclones (south and north of the equator) over the western Pacific. The AUS region is under control of the southern anticyclone, thereby reducing the CLT and increasing the DTR in AUS as a result of anomalous descending motion. In contrast, the EA region is controlled by anomalous southerlies to the west of the northern anticyclone. The northward transports of moistures from the warm ocean increase the CLT, reducing DTR in EA. © 2018 American Meteorological Society."
"25924917300;6603379376;57193732561;8673317400;57217502449;6603585835;6701843178;","Application of remote sensing techniques to study aerosol water vapour uptake in a real atmosphere",2018,"10.1016/j.atmosres.2017.11.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034604833&doi=10.1016%2fj.atmosres.2017.11.020&partnerID=40&md5=6dfb8461cf7fcf52fda80d5af6dbe0eb","In this work, a study of several observations of aerosol water uptake in a real (non-controlled) atmosphere, registered by remote sensing techniques, are presented. In particular, three events were identified within the Atmospheric Boundary Layer (ABL) and other two events were detected in the free troposphere (beyond the top of the ABL). Then, aerosol optical properties were measured at different relative humidity (RH) conditions by means of a multi-wavelength (MW) Raman lidar located at CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Research Centre for Energy, Environment and Technology) facilities in Madrid (Spain). Additionally, aerosol optical and microphysical properties provided by automatic sun and sky scanning spectral radiometers (CIMEL CE-318) and a meteorological analysis complement the study. However, a detailed analysis only could be carried out for the cases observed within the ABL since well-mixed atmospheric layers are required to properly characterize these processes. This characterization of aerosol water uptake is based on the curve described by the backscatter coefficient at 532 nm as a function of RH which allows deriving the enhancement factor. Thus, the Hänel parameterization is utilized, and the results obtained are in the range of values reported in previous studies, which shows the suitability of this approach to study such hygroscopic processes. Furthermore, the anti-correlated pattern observed on backscatter-related Ångström exponent (532/355 nm) and RH indicates plausible signs of aerosol hygroscopic growth. According to the meteorological analysis performed, we attribute such hygroscopic behaviour to marine aerosols which are advected from the Atlantic Ocean to the low troposphere in Madrid. We have also observed an interesting response of aerosols to RH at certain levels which it is suggested to be due to a hysteresis process. The events registered in the free troposphere, which deal with volcano and wild fire plumes transported at higher altitudes, indicate that these processes can take place in the free troposphere, where the climate relevance can be rather different considering the role of aerosol as cloud condensation nuclei. © 2017 Elsevier B.V."
"57202072291;","Role of Eastern Ghats orography and cold pool in an extreme rainfall event over Chennai on 1 December 2015",2018,"10.1175/MWR-D-16-0473.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047084654&doi=10.1175%2fMWR-D-16-0473.1&partnerID=40&md5=97a670a077a120bd5bf1b01aeb6fd026","Chennai and its surrounding region received extreme rainfall on 1 December 2015. A rain gauge in the city recorded 494 mm of rainfall within a span of 24 h-at least a 100-yr event. The convective system was stationary over the coast during the event. This study analyzes how the Eastern Ghats orography and moist processes localized the rainfall. ERA-Interim data show a low-level easterly jet (LLEJ) over the adjacent ocean and a barrier jet over the coast during the event. A control simulation with the nonhydrostatic Weather Research and Forecasting (WRF) Model shows that the Eastern Ghats obstructed the precipitation-driven cold pool from moving downstream, resulting in the cold pool piling up and remaining stationary in the upwind direction. The cold pool became weak over the ocean. It stratified the subcloud layer and decelerated the flow ahead of the orography; hence, the flow entered a blocked regime. Maximum deceleration of the winds and uplifting happened at the edge of the cold pool over the coast. Therefore, a stationary convective system and maximum rainfall occurred at the coast. As a result of orographic blocking, propagation of a low pressure system (LPS) was obstructed. Because of the topographic β effect, the LPS subsequently traveled a southward path. In a sensitivity experiment without the orography, the cold pool was swept downstream by the winds; clouds moved inland. In the second experiment with no evaporative cooling of rain, the cold pool did not form; flow, as well as clouds, moved over the orography. © 2018 American Meteorological Society."
"56424145700;8591161400;7003278104;7405489798;7102567936;7006198994;7406372329;24485218400;8839231800;","Dynamics-oriented diagnostics for the Madden-Julian oscillation",2018,"10.1175/JCLI-D-17-0332.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047084658&doi=10.1175%2fJCLI-D-17-0332.1&partnerID=40&md5=4bde8f98ca5928373ff4691d100dff17","Realistic simulations of the Madden-Julian oscillation (MJO) by global climate models (GCMs) remain a great challenge. To evaluate GCM simulations of the MJO, the U.S. CLIVAR MJO Working Group developed a standardized set of diagnostics, providing a comprehensive assessment of statistical properties of the MJO. Here, a suite of complementary diagnostics has been developed that provides discrimination and assessment of MJO simulations based on the perception that the MJO propagation has characteristic dynamic and thermodynamic structures. The new dynamics-oriented diagnostics help to evaluate whether a model produces eastward-propagating MJOs for the right reasons. The diagnostics include 1) the horizontal structure of boundary layer moisture convergence (BLMC) that moistens the lower troposphere to the east of a convection center, 2) the preluding eastward propagation of BLMC that leads the propagation of MJO precipitation by about 5 days, 3) the horizontal structure of 850-hPa zonal wind and its equatorial asymmetry (Kelvin easterly versus Rossby westerly intensity), 4) the equatorial vertical-longitudinal structure of the equivalent potential temperature and convective instability index that reflects the premoistening and predestabilization processes, 5) the equatorial vertical-longitudinal distribution of diabatic heating that reflects the multicloud structure of the MJO, 6) the upper-level divergence that reflects the influence of stratiform cloud heating, and 7) the MJO available potential energy generation that reflects the amplification and propagation of an MJO. The models that simulate better three-dimensional dynamic and thermodynamic structures of MJOs generally reproduce better eastward propagations. This evaluation identifies a number of shortcomings in representing dynamical and heating processes relevant to the MJO simulation and reveals potential sources of the shortcomings. © 2018 American Meteorological Society."
"56925998900;7003466102;","The Response of the Ocean Thermal Skin Layer to Variations in Incident Infrared Radiation",2018,"10.1002/2017JC013351","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044845077&doi=10.1002%2f2017JC013351&partnerID=40&md5=bbe5cd4d7fd0317a2019ce5cfff6c893","Ocean warming trends are observed and coincide with the increase in concentrations of greenhouse gases in the atmosphere resulting from human activities. At the ocean surface, most of the incoming infrared (IR) radiation is absorbed within the top micrometers of the ocean's surface where the thermal skin layer (TSL) exists. Thus, the incident IR radiation does not directly heat the upper few meters of the ocean. This paper investigates the physical mechanism between the absorption of IR radiation and its effect on heat transfer at the air-sea boundary. The hypothesis is that given the heat lost through the air-sea interface is controlled by the TSL, the TSL adjusts in response to variations in incident IR radiation to maintain the surface heat loss. This modulates the flow of heat from below and hence controls upper ocean heat content. This hypothesis is tested using the increase in incoming longwave radiation from clouds and analyzing vertical temperature profiles in the TSL retrieved from sea-surface emission spectra. The additional energy from the absorption of increasing IR radiation adjusts the curvature of the TSL such that the upward conduction of heat from the bulk of the ocean into the TSL is reduced. The additional energy absorbed within the TSL supports more of the surface heat loss. Thus, more heat beneath the TSL is retained leading to the observed increase in upper ocean heat content. © 2018. The Authors."
"57197765943;24449131600;","Parameter and state estimation with ensemble Kalman filter based algorithms for convective-scale applications",2018,"10.1002/qj.3257","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052499073&doi=10.1002%2fqj.3257&partnerID=40&md5=62189822b6dcaf256c47203d0f831a3a","Representation of clouds in convection-permitting models is sensitive to numerical weather prediction (NWP) model parameters that are often very crudely known (for example roughness length). Our goal is to allow for uncertainty in these parameters and estimate them from data using the ensemble Kalman filter (EnKF) approach. However, to deal with difficulties associated with convective-scale applications, such as non-Gaussianity and constraints on state and parameter values, modifications to classical EnKF are necessary. In this article, we evaluate and extend several recently developed EnKF-based algorithms that either incorporate constraints such as mass conservation and positivity of precipitation explicitly or introduce higher order moments on the joint state and parameter estimation problem. We compare their results with the localized EnKF for a common idealized test case. The test case uses perfect model experiments with the one-dimensional modified shallow-water model, which was designed to mimic important properties of convection. We use a stochastic dynamical model for parameters, in order to prevent underdispersion in parameter space. To deal with localization for estimation of parameters, we introduce a method called global updating, which is a computationally cheap modification of spatial updating and was proven successful in this context. The sensitivity of the results to the number of ensemble members and localization, as well as observation coverage and frequency, is shown. Although all algorithms are capable of reducing the initial state and parameter errors, it is concluded that mass conservation is important when the localization radius is small and/or the observations are sparse. In addition, accounting for higher order moments in the joint space and parameter estimation problem is beneficial when the ensemble size is large enough or when applied to parameter estimation only. © 2018 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57203544786;7402579146;56284582200;","The role of mesoscale instabilities in the sting-jet dynamics of windstorm Tini",2018,"10.1002/qj.3264","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052489752&doi=10.1002%2fqj.3264&partnerID=40&md5=f31eca635c8dbb84f50e30a6deb3d0c1","Sting jets (SJs) occur as an additional region of low-level strong winds in some Shapiro–Keyser-type extratropical cyclones. While SJs are widely accepted as being distinct from the warm and cold conveyor belts, the mechanisms responsible for their occurrence are still not fully understood. Here we determine the relative importance of the release of mesoscale instabilities and synoptic-scale cyclone dynamics, so addressing an area of current debate. Numerical weather prediction simulations of a SJ-containing windstorm are analysed and Lagrangian trajectories used to assess the evolution of, and mesoscale atmospheric instabilities (e.g. symmetric and inertial instabilities) in, the descending airstream. The SJ undergoes a two-stage descent: cooling via sublimation followed by a large acceleration accompanied by instability release. Combined tilting and stretching of vorticity play a major role in the local onset of instability on the airstream. Vorticity and frontogenesis fields have a narrow slantwise banded structure in the cloud head and around the SJ; the descending SJ modifies the widespread frontolysis expected from the large-scale dynamics alone in the frontal-fracture region. A coarser-resolution simulation also generates strong winds in the frontal-fracture region, although these are significantly weaker than in the higher-resolution simulation. The SJ airstream in the coarser-resolution simulation undergoes a weaker descent without instability generation and descends in a widespread frontolytic region. Hence, while the SJ undergoes a process of destabilisation that enhances its descent and acceleration in the higher-resolution simulation, enhancing the strong winds already generated by the synoptic-scale cyclone dynamics, this destabilisation does not occur in the SJ produced by a coarser-resolution simulation, resulting in weaker winds. This analysis reveals the synergy between the paradigms of SJ occurrence through the release of mesoscale instabilities and synoptic-scale cyclone dynamics and demonstrates that the current debate may in part be a consequence of the model resolutions used by different studies. © 2018 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"36193302500;25634932400;15759136500;","Relationship between vegetation structure and microenvironment in Fagus grandifolia subsp. mexicana forest relicts in Mexico",2018,"10.1093/jpe/rtw138","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044649775&doi=10.1093%2fjpe%2frtw138&partnerID=40&md5=13e0d6ba268ffea13eb27e5181594b40","Aims Changes in the structure and composition of forests, whether caused by natural or anthropic events, alter the microenvironment, sometimes irreversibly. Since the local environment has a direct impact on basic ecological processes, this has become a key component of research. Mexican beech forests (Fagus grandifolia subsp. mexicana) in the Sierra Madre Oriental are restricted to sites with specific climate, soils and topography, making them an ideal natural system for ecological research. The objectives of this study were to identify the relationship between the microenvironment and the tree and shrub structure and composition of Mexican beech forests in the state of Hidalgo, and to compare the floristic similarity of these forests on the country scale using data from seven localities. Methods Specimens were collected for a period of one year at all localities in the state of Hidalgo where beech forests are located. At each locality, five 400 m2 plots were established, and structural attributes (basal area, coverage, density and species richness) and six environmental variables were measured in the plots. The relationship between structure and microenvironment was estimated by simple correlation and canonic correspondence analysis (CCA). in addition, floristic similarity between different beech forest localities in the Sierra Madre Oriental was estimated by correspondence analysis (CA). Important Findings Twenty tree species and eight shrub species were identified; at all localities studied F. grandifolia subsp. mexicana dominated the canopy. The multivariate analysis indicated that (i) in the four localities in the state of Hidalgo, all microenvironmental variables except pH are related to the variation observed in species composition and structure; (ii) the El Gosco locality had both tree and shrub species and microenvironmental factors different from those observed in the Fagus forests at the other localities in the study and (iii) the localities studied in order to draw country-scale comparisons could be divided into three groups by floristic similarity. The first group consisted of the Hidalgo localities, the second of the Veracruz localities, and the third, more different from the others, of the Tamaulipas locality. The results of this study provide the first reference for the relationship between the range of microenvironments and species structure in Mexican beech forests. Microenvironmental conditions in the larger beech forests could be used as a model for designing management and conservation programs for this plant association. Because of its particular ecological and historical characteristics, this association could serve as an example of biodiversity conservation in Mexico. © The Author(s) 2016. Published by Oxford University Press on behalf of the Institute of Botany, Chinese Academy of Sciences and the Botanical Society of China. All rights reserved."
"55235064100;24766022200;57195943208;7202296460;8695340600;36155944700;","Impact of summer monsoon on the elevation-dependence of meteorological variables in the south of central Himalaya",2018,"10.1002/joc.5293","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030323563&doi=10.1002%2fjoc.5293&partnerID=40&md5=4677d65d1d68e8a0c3ee580db236b9e4","The South Asian summer monsoon brings abundant precipitation and associated latent heat release to the south of central Himalaya, and alters hydrothermal conditions of this region. This study explored the impact of South Asian summer monsoon on the elevation-dependence of meteorological variables along the south slope of Mt. Everest in the central Himalaya, which is crucial to modelling the glacio-hydrological processes in this elevated region. The data were collected at five stations deployed at 2660–5600 m above sea level (asl) along the slope during 2007–2011. Major findings are the following: (1) The amount of precipitation during the monsoon season usually decreases with elevation but it is relatively uniform between 3600 and 5000 m asl. This uniform profile may be attributed to the monsoon–terrain–land interactions, particularly to the retard effect of glacier cooling on daytime upvalley wind; (2) Cloud shielding effects cause lower solar radiation and higher downward longwave radiation in the monsoon than in the other seasons. In particular, higher elevations have more clouds in the afternoon, resulting in an abnormal elevation-dependence of solar radiation (i.e. higher elevations receive less solar radiation); (3) Strong daytime upvalley wind and moist convection homogenizes the vertical distributions of air mass along the slope, causing a constant lapse rate of both surface air temperature and dew-point temperature (representing humidity) during typical monsoon months, but this phenomenon is not found in the other seasons. These findings provide critical guidance for extrapolating the meteorological variables from lower to higher elevations in this region. © 2017 Royal Meteorological Society"
"8211360900;57190180699;56880193400;57056609200;","Long-term change of potential evapotranspiration over southwest China and teleconnections with large-scale climate anomalies",2018,"10.1002/joc.5309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043381497&doi=10.1002%2fjoc.5309&partnerID=40&md5=46db3a82771ccff98565ccdfed1f7f6e","Potential evapotranspiration (PET) is a sensitive factor for atmospheric and ecological systems over southwest China which is characterized by intensive karst geomorphology and fragile environment. Based on daily meteorological data of 94 stations during 1961–2013, the spatiotemporal characteristics of PET are analysed. The changing characteristics of local meteorological factors and large-scale climatic features are also investigated to explain the potential reasons for changing PET. Study results are as follows: (1) The high-value centre of PET with a mean value of 1097 mm a−1 locates in the south mainly resulted from the regional climatic features of higher air temperature (TEM), sunshine duration (SSD) and lower relative humidity (RHU), and the low-value centre of PET with a mean value of 831 mm a−1 is in the northeast primarily attributed to higher RHU and weaker SSD. (2) Annual PET decreases at −10.04 mm decade−1 before the year 2000 but increases at 50.65 mm decade−1 thereafter, and the dominant factors of PET change are SSD, RHU and wind speed (WIN), with the relative contributions of 33.29, 25.42 and 22.16%, respectively. (3) The abrupt change of PET in 2000 is strongly dominated by large-scale climatic anomalies. The strengthened 850 hPa geostrophic wind (0.51 m s−1 decade−1), weakened total cloud cover (−2.25% decade−1) and 500 hPa water vapour flux (−2.85% decade−1) have provided advantageous dynamic, thermal and dry conditions for PET over southwest China since the 21st century. © 2017 Royal Meteorological Society"
"54783792600;7410041005;6603431534;6701333444;57201418252;57217772325;","Ice particle production in mid-level stratiform mixed-phase clouds observed with collocated A-Train measurements",2018,"10.5194/acp-18-4317-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044727115&doi=10.5194%2facp-18-4317-2018&partnerID=40&md5=d51f9eb4278da0933eb8b2b0e5ac0391","Collocated A-Train CloudSat radar and CALIPSO lidar measurements between 2006 and 2010 are analyzed to study primary ice particle production characteristics in mid-level stratiform mixed-phase clouds on a global scale. For similar clouds in terms of cloud top temperature and liquid water path, Northern Hemisphere latitude bands have layer-maximum radar reflectivity (ZL) that is ∼ 1 to 8dBZ larger than their counterparts in the Southern Hemisphere. The systematically larger ZL under similar cloud conditions suggests larger ice number concentrations in mid-level stratiform mixed-phase clouds over the Northern Hemisphere, which is possibly related to higher background aerosol loadings. Furthermore, we show that springtime northern mid-and high latitudes have ZL that is larger by up to 6dBZ (a factor of 4 higher ice number concentration) than other seasons, which might be related to more dust events that provide effective ice nucleating particles. Our study suggests that aerosol-dependent ice number concentration parameterizations are required in climate models to improve mixed-phase cloud simulations, especially over the Northern Hemisphere. © Author(s) 2018."
"57201352727;56572170400;57201350004;7404105326;","Framing Climate Goals in Terms of Cumulative CO2-Forcing-Equivalent Emissions",2018,"10.1002/2017GL076173","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044418054&doi=10.1002%2f2017GL076173&partnerID=40&md5=f1f240f89d4e85ff2bbf51806d9106d1","The relationship between cumulative CO2 emissions and CO2-induced warming is determined by the Transient Climate Response to Emissions (TCRE), but total anthropogenic warming also depends on non-CO2 forcing, complicating the interpretation of emissions budgets based on CO2 alone. An alternative is to frame emissions budgets in terms of CO2-forcing-equivalent (CO2-fe) emissions—the CO2 emissions that would yield a given total anthropogenic radiative forcing pathway. Unlike conventional “CO2-equivalent” emissions, these are directly related to warming by the TCRE and need to fall to zero to stabilize warming: hence, CO2-fe emissions generalize the concept of a cumulative carbon budget to multigas scenarios. Cumulative CO2-fe emissions from 1870 to 2015 inclusive are found to be 2,900 ± 600 GtCO2-fe, increasing at a rate of 67 ± 9.5 GtCO2-fe/yr. A TCRE range of 0.8–2.5°C per 1,000 GtC implies a total budget for 0.6°C of additional warming above the present decade of 880–2,750 GtCO2-fe, with 1,290 GtCO2-fe implied by the Coupled Model Intercomparison Project Phase 5 median response, corresponding to 19 years' CO2-fe emissions at the current rate. ©2018. American Geophysical Union. All Rights Reserved."
"57201123684;7401936984;7402064802;22635190100;56763174500;25926762100;14045744500;7003582587;","CAUSES: Diagnosis of the Summertime Warm Bias in CMIP5 Climate Models at the ARM Southern Great Plains Site",2018,"10.1002/2017JD027200","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044292305&doi=10.1002%2f2017JD027200&partnerID=40&md5=5f0828021389dbe59b108b4bfc128d31","All the weather and climate models participating in the Clouds Above the United States and Errors at the Surface project show a summertime surface air temperature (T2 m) warm bias in the region of the central United States. To understand the warm bias in long-term climate simulations, we assess the Atmospheric Model Intercomparison Project simulations from the Coupled Model Intercomparison Project Phase 5, with long-term observations mainly from the Atmospheric Radiation Measurement program Southern Great Plains site. Quantities related to the surface energy and water budget, and large-scale circulation are analyzed to identify possible factors and plausible links involved in the warm bias. The systematic warm season bias is characterized by an overestimation of T2 m and underestimation of surface humidity, precipitation, and precipitable water. Accompanying the warm bias is an overestimation of absorbed solar radiation at the surface, which is due to a combination of insufficient cloud reflection and clear-sky shortwave absorption by water vapor and an underestimation in surface albedo. The bias in cloud is shown to contribute most to the radiation bias. The surface layer soil moisture impacts T2 m through its control on evaporative fraction. The error in evaporative fraction is another important contributor to T2 m. Similar sources of error are found in hindcast from other Clouds Above the United States and Errors at the Surface studies. In Atmospheric Model Intercomparison Project simulations, biases in meridional wind velocity associated with the low-level jet and the 500 hPa vertical velocity may also relate to T2 m bias through their control on the surface energy and water budget. ©2018. The Authors."
"19933330400;55574231850;55899884100;35113492400;","The Microphysical Properties of Convective Precipitation Over the Tibetan Plateau by a Subkilometer Resolution Cloud-Resolving Simulation",2018,"10.1002/2017JD027812","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044514479&doi=10.1002%2f2017JD027812&partnerID=40&md5=dab78db06a3c0dd5268a9d9eb325bc0e","The microphysical properties of convective precipitation over the Tibetan Plateau are unique because of the extremely high topography and special atmospheric conditions. In this study, the ground-based cloud radar and disdrometer observations as well as high-resolution Weather Research and Forecasting simulations with the Chinese Academy of Meteorological Sciences microphysics and four other microphysical schemes are used to investigate the microphysics and precipitation mechanisms of a convection event on 24 July 2014. The Weather Research and Forecasting-Chinese Academy of Meteorological Sciences simulation reasonably reproduces the spatial distribution of 24-hr accumulated rainfall, yet the temporal evolution of rain rate has a delay of 1–3 hr. The model reflectivity shares the common features with the cloud radar observations. The simulated raindrop size distributions demonstrate more of small- and large-size raindrops produced with the increase of rain rate, suggesting that changeable shape parameter should be used in size distribution. Results show that abundant supercooled water exists through condensation of water vapor above the freezing layer. The prevailing ice crystal microphysical processes are depositional growth and autoconversion of ice crystal to snow. The dominant source term of snow/graupel is riming of supercooled water. Sedimentation of graupel can play a vital role in the formation of precipitation, but melting of snow is rather small and quite different from that in other regions. Furthermore, water vapor budgets suggest that surface moisture flux be the principal source of water vapor and self-circulation of moisture happen at the beginning of convection, while total moisture flux convergence determine condensation and precipitation during the convective process over the Tibetan Plateau. ©2018. The Authors."
"12808494200;7402425067;6701416358;35868180800;55718857500;6506276837;","Characterization of Wildfire-Induced Aerosol Emissions From the Maritime Continent Peatland and Central African Dry Savannah with MISR and CALIPSO Aerosol Products",2018,"10.1002/2017JD027415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044249499&doi=10.1002%2f2017JD027415&partnerID=40&md5=564141401e6ff04b27cd254bbc872514","Aerosol plumes from wildfires affect the Earth's climate system through regulation of the radiative budget and clouds. However, optical properties of aerosols from individual wildfire smoke plumes and their resultant impact on regional climate are highly variable. Therefore, there is a critical need for observations that can constrain the partitioning between different types of aerosols. Here we present the apparent influence of regional ecosystem types on optical properties of wildfire-induced aerosols based on remote sensing observations from two satellite instruments and three ground stations. The independent observations commonly show that the ratio of the absorbing aerosols is significantly lower in smoke plumes from the Maritime Continent than those from Central Africa, so that their impacts on regional climate are different. The observed light-absorbing properties of wildfire-induced aerosols are explained by dominant ecosystem types such as wet peatlands for the Maritime Continent and dry savannah for Central Africa, respectively. These results suggest that the wildfire-aerosol-climate feedback processes largely depend on the terrestrial environments from which the fires originate. These feedbacks also interact with climate under greenhouse warming. Our analysis shows that aerosol optical properties retrieved based on satellite observations are critical in assessing wildfire-induced aerosols forcing in climate models. The optical properties of carbonaceous aerosol mixtures used by state-of-the-art chemistry climate models may overestimate emissions for absorbing aerosols from wildfires over the Maritime Continent. ©2018. American Geophysical Union. All Rights Reserved."
"57194279036;7003904922;","Parameterization of In-Cloud Aerosol Scavenging Due To Atmospheric Ionization: 2. Effects of Varying Particle Density",2018,"10.1002/2017JD027884","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044186397&doi=10.1002%2f2017JD027884&partnerID=40&md5=b6655a77cf04c8e4e9dd50545948b7df","Simulations and parameterization of collision rate coefficients for aerosol particles with 3 μm radius droplets have been extended to a range of particle densities up to 2,000 kg m−3 for midtropospheric (~5 km) conditions (540 hPa, −17°C). The increasing weight has no effect on collisions for particle radii less than 0.2 μm, but for greater radii the weight effect becomes significant and usually decreases the collision rate coefficient. When increasing size and density of particles make the fall speed of the particle relative to undisturbed air approach to that of the droplet, the effect of the particle falling away in the stagnation region ahead of the droplet becomes important, and the probability of frontside collisions can decrease to zero. Collisions on the rear side of the droplet can be enhanced as particle weight increases, and for this the weight effect tends to increase the rate coefficients. For charges on the droplet and for large particles with density ρ < 1,000 kg m−3 the predominant effect increases in rate coefficient due to the short-range attractive image electric force. With density ρ above about 1,000 kg m−3, the stagnation region prevents particles moving close to the droplet and reduces the effect of these short-range forces. Together with previous work, it is now possible to obtain collision rate coefficients for realistic combinations of droplet charge, particle charge, droplet radius, particle radius, particle density, and relative humidity in clouds. The parameterization allows rapid access to these values for use in cloud models. ©2018. American Geophysical Union. All Rights Reserved."
"6506835389;6603716679;6701650121;7003557662;","Optimizing UV Index determination from broadband irradiances",2018,"10.5194/gmd-11-1093-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044784314&doi=10.5194%2fgmd-11-1093-2018&partnerID=40&md5=6b0f4a1e81f143561e2998313a538105","A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00nm is typically greater than 95% for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0%. However, underestimations of clear-sky GEM irradiances were found on the order of ∼30-50% for the 294.12-310.70nm band and by a factor of ∼30 for the 280.11-294.12nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0.2-0.3 with a root-mean-square relative error in the scatter of ∼6.6% for clear-sky conditions. Similar results are reproduced under cloudy conditions with light to moderate clouds, with a relative error comparable to the clear-sky counterpart; under strong attenuation due to clouds, a substantial increase in the root-mean-square relative error of up to 35% is observed due to differing cloud radiative transfer models. © 2018 Copernicus GmbH. All rights reserved."
"26032229000;14066601400;56151746000;55470017900;35463545000;36117910700;25227357000;7102113229;","Impact of varying lidar measurement and data processing techniques in evaluating cirrus cloud and aerosol direct radiative effects",2018,"10.5194/amt-11-1639-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044428798&doi=10.5194%2famt-11-1639-2018&partnerID=40&md5=85a13aa190984e3fe248279c1d6f6eba","In the past 2 decades, ground-based lidar networks have drastically increased in scope and relevance, thanks primarily to the advent of lidar observations from space and their need for validation. Lidar observations of aerosol and cloud geometrical, optical and microphysical atmospheric properties are subsequently used to evaluate their direct radiative effects on climate. However, the retrievals are strongly dependent on the lidar instrument measurement technique and subsequent data processing methodologies. In this paper, we evaluate the discrepancies between the use of Raman and elastic lidar measurement techniques and corresponding data processing methods for two aerosol layers in the free troposphere and for two cirrus clouds with different optical depths. Results show that the different lidar techniques are responsible for discrepancies in the model-derived direct radiative effects for biomass burning (0.05 W m-2 at surface and 0.007 W m-2 at top of the atmosphere) and dust aerosol layers (0.7 W m-2 at surface and 0.85 W m-2 at top of the atmosphere). Data processing is further responsible for discrepancies in both thin (0.55 W m-2 at surface and 2.7 W m-2 at top of the atmosphere) and opaque (7.7 W m-2 at surface and 11.8 W m-2 at top of the atmosphere) cirrus clouds. Direct radiative effect discrepancies can be attributed to the larger variability of the lidar ratio for aerosols (20-150 sr) than for clouds (20-35 sr). For this reason, the influence of the applied lidar technique plays a more fundamental role in aerosol monitoring because the lidar ratio must be retrieved with relatively high accuracy. In contrast, for cirrus clouds, with the lidar ratio being much less variable, the data processing is critical because smoothing it modifies the aerosol and cloud vertically resolved extinction profile that is used as input to compute direct radiative effect calculations. © 2018 Author(s)."
"57132505500;8967643200;6603909200;6506579671;","Changes in Andes snow cover from MODIS data, 2000-2016",2018,"10.5194/tc-12-1027-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044409220&doi=10.5194%2ftc-12-1027-2018&partnerID=40&md5=f4eae53a4882a4a129b716c233484fbf","The Andes span a length of 7000 km and are important for sustaining regional water supplies. Snow variability across this region has not been studied in detail due to sparse and unevenly distributed instrumental climate data. We calculated snow persistence (SP) as the fraction of time with snow cover for each year between 2000 and 2016 from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensors (500 m, 8-day maximum snow cover extent). This analysis is conducted between 8 and 36- S due to high frequency of cloud (>30% of the time) south and north of this range. We ran Mann-Kendall and Theil-Sens analyses to identify areas with significant changes in SP and snowline (the line at lower elevation where SPD20 %). We evaluated how these trends relate to temperature and precipitation from Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA2) and University of Delaware datasets and climate indices as El Niño-Southern Oscillation (ENSO), Southern Annular Mode (SAM), and Pacific Decadal Oscillation (PDO). Areas north of 29° S have limited snow cover, and few trends in snow persistence were detected. A large area (34 370 km2) with persistent snow cover between 29 and 36- S experienced a significant loss of snow cover (2-5 fewer days of snow year-1). Snow loss was more pronounced (62% of the area with significant trends) on the east side of the Andes.We also found a significant increase in the elevation of the snowline at 10-30myear1 south of 29- 30° S. Decreasing SP correlates with decreasing precipitation and increasing temperature, and the magnitudes of these correlations vary with latitude and elevation. ENSO climate indices better predicted SP conditions north of 31° S, whereas the SAM better predicted SP south of 31° S. © 2018 Author(s) 2018."
"57132245900;6603813334;","Volcanic ash modeling with the NMMB-MONARCH-ASH model: Quantification of offline modeling errors",2018,"10.5194/acp-18-4019-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044333425&doi=10.5194%2facp-18-4019-2018&partnerID=40&md5=a2ed0fdcfa697e9e3e09ee71bd06c3aa","Volcanic ash modeling systems are used to simulate the atmospheric dispersion of volcanic ash and to generate forecasts that quantify the impacts from volcanic eruptions on infrastructures, air quality, aviation, and climate. The efficiency of response and mitigation actions is directly associated with the accuracy of the volcanic ash cloud detection and modeling systems. Operational forecasts build on offline coupled modeling systems in which meteorological variables are updated at the specified coupling intervals. Despite the concerns from other communities regarding the accuracy of this strategy, the quantification of the systematic errors and shortcomings associated with the offline modeling systems has received no attention. This paper employs the NMMB-MONARCH-ASH model to quantify these errors by employing different quantitative and categorical evaluation scores. The skills of the offline coupling strategy are compared against those from an online forecast considered to be the best estimate of the true outcome. Case studies are considered for a synthetic eruption with constant eruption source parameters and for two historical events, which suitably illustrate the severe aviation disruptive effects of European (2010 Eyjafjallajökull) and South American (2011 Cordón Caulle) volcanic eruptions. Evaluation scores indicate that systematic errors due to the offline modeling are of the same order of magnitude as those associated with the source term uncertainties. In particular, traditional offline forecasts employed in operational model setups can result in significant uncertainties, failing to reproduce, in the worst cases, up to 45-70 % of the ash cloud of an online forecast. These inconsistencies are anticipated to be even more relevant in scenarios in which the meteorological conditions change rapidly in time. The outcome of this paper encourages operational groups responsible for real-time advisories for aviation to consider employing computationally efficient online dispersal models. © Author(s) 2018."
"57202055774;7005387538;57189595246;24074386100;6603545358;24764399200;","Modeling winter precipitation over the Juneau Icefield, Alaska, using a linear model of orographic precipitation",2018,"10.3389/feart.2018.00020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046992631&doi=10.3389%2ffeart.2018.00020&partnerID=40&md5=3c00d7547742e1118f51ffc83f3a161a","Assessing and modeling precipitation in mountainous areas remains a major challenge in glacier mass balance modeling. Observations are typically scarce and reanalysis data and similar climate products are too coarse to accurately capture orographic effects. Here we use the linear theory of orographic precipitation model (LT model) to downscale winter precipitation from the Weather Research and Forecasting Model (WRF) over the Juneau Icefield, one of the largest ice masses in North America (>4,000 km2), for the period 1979–2013. The LT model is physically-based yet computationally efficient, combining airflowdynamics and simple cloud microphysics. The resulting 1 kmresolution precipitation fields showsubstantially reducedprecipitation on the northeastern portion of the icefield compared to the southwestern side, a pattern that is not well captured in the coarse resolution (20 km) WRF data. Net snow accumulation derived from the LT model precipitation agrees well with point observations across the icefield. To investigate the robustness of the LT model results, we performa series of sensitivity experiments varying hydrometeor fall speeds, the horizontal resolution of the underlying grid, and the source of the meteorological forcing data. The resulting normalized spatial precipitation pattern is similar for all sensitivity experiments, but local precipitation amounts vary strongly, with greatest sensitivity to variations in snowfall speed. Results indicate that the LT model has great potential to provide improved spatial patterns of winter precipitation for glacier mass balance modeling purposes in complex terrain, but ground observations are necessary to constrain model parameters to match total amounts. © 2018 Roth, Hock, Schuler, Bieniek, Pelto and Aschwanden."
"57195578500;56502000100;57195805362;8899985400;55729666100;7004462227;26639062900;26434854300;","Secondary sulfate is internally mixed with sea spray aerosol and organic aerosol in the winter Arctic",2018,"10.5194/acp-18-3937-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044249867&doi=10.5194%2facp-18-3937-2018&partnerID=40&md5=f738c9cf70b3c2a9c5e879780fcf44ca","Few measurements of aerosol chemical composition have been made during the winter-spring transition (following polar sunrise) to constrain Arctic aerosol-cloud- climate feedbacks. Herein, we report the first measurements of individual particle chemical composition near Utqia-gvik (Barrow), Alaska, in winter (seven sample days in January and February 2014). Individual particles were analyzed by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX, 24 847 particles), Raman microspectroscopy (300 particles), and scanning transmission X-ray microscopy with nearedge X-ray absorption fine structure spectroscopy (STXMNEXAFS, 290 particles). Sea spray aerosol (SSA) was observed in all samples, with fresh and aged SSA comprising 99 %, by number, of 2.5-7.5 μm diameter particles, 65- 95% from 0.5-2.5 μm, and 50-60% from 0.1-0.5 μm, indicating SSA is the dominant contributor to accumulation and coarse-mode aerosol during the winter. The aged SSA particles were characterized by reduced chlorine content with 94 %, by number, internally mixed with secondary sulfate (39 %, by number, internally mixed with both nitrate and sulfate), indicative of multiphase aging reactions during transport. There was a large number fraction (40% of 1.0-4.0 μm diameter particles) of aged SSA during periods when particles were transported from near Prudhoe Bay, consistent with pollutant emissions from the oil fields participating in atmospheric processing of aerosol particles. Organic carbon and sulfate particles were observed in all samples and comprised 40-50 %, by number, of 0.1-0.4 μm diameter particles, indicative of Arctic haze influence. Soot was internally mixed with organic and sulfate components. All sulfate was mixed with organic carbon or SSA particles. Therefore, aerosol sources in the Alaskan Arctic and resulting aerosol chemical mixing states need to be considered when predicting aerosol climate effects, particularly cloud formation, in the winter Arctic. © 2018 Author(s)."
"56117999100;56518310300;7006375009;","A machine-learning approach to forecasting remotely sensed vegetation health",2018,"10.1080/01431161.2017.1410296","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046946925&doi=10.1080%2f01431161.2017.1410296&partnerID=40&md5=50fe9e40179124b0b82e629dcd26f216","Drought threatens food and water security around the world, and this threat is likely to become more severe under climate change. High resolution predictive information can help farmers, water managers, and others to manage the effects of drought. We have created an open-source tool to produce short-term forecasts of vegetation health at high spatial resolution, using data that are global in coverage. The tool automates downloading and processing Moderate Resolution Imaging Spectroradiometer (MODIS) data sets and training gradient boosted machine models on hundreds of millions of observations to predict future values of the enhanced vegetation index. We compared the predictive power of different sets of variables (MODIS surface reflectance data and Level-3 MODIS products) in two regions with distinct agro-ecological systems, climates, and cloud coverage: Sri Lanka and California. Performance in California is higher because of more cloud-free days and less missing data. In both regions, the correlation between the actual and model predicted vegetation health values in agricultural areas is above 0.75. Predictive power more than doubles in agricultural areas compared to a baseline model. © 2017 The Author(s)."
"35775565200;26643440200;12242677000;54408652100;7004540083;","The International Satellite Cloud Climatology Project H-Series climate data record product",2018,"10.5194/essd-10-583-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044008726&doi=10.5194%2fessd-10-583-2018&partnerID=40&md5=2ab3bbe9d5c7a8f08d727349eb5c02ce","This paper describes the new global long-term International Satellite Cloud Climatology Project (ISCCP) H-series climate data record (CDR). The H-series data contain a suite of level 2 and 3 products for monitoring the distribution and variation of cloud and surface properties to better understand the effects of clouds on climate, the radiation budget, and the global hydrologic cycle. This product is currently available for public use and is derived from both geostationary and polar-orbiting satellite imaging radiometers with common visible and infrared (IR) channels. The H-series data currently span July 1983 to December 2009 with plans for continued production to extend the record to the present with regular updates. The H-series data are the longest combined geostationary and polar orbiter satellite-based CDR of cloud properties. Access to the data is provided in network common data form (netCDF) and archived by NOAA's National Centers for Environmental Information (NCEI) under the satellite Climate Data Record Program targetCombining double low line). The basic characteristics, history, and evolution of the dataset are presented herein with particular emphasis on and discussion of product changes between the H-series and the widely used predecessor D-series product which also spans from July 1983 through December 2009. Key refinements included in the ISCCP H-series CDR are based on improved quality control measures, modified ancillary inputs, higher spatial resolution input and output products, calibration refinements, and updated documentation and metadata to bring the H-series product into compliance with existing standards for climate data records. © Author(s) 2018."
"22635190100;7402064802;7401936984;57201123684;56763174500;25629055800;14045744500;25926762100;7003582587;13006055400;7102266120;6602504047;8397494800;7102425008;8922308700;8042408300;55796504300;7004485409;55802246600;36187387300;57001643600;","CAUSES: On the Role of Surface Energy Budget Errors to the Warm Surface Air Temperature Error Over the Central United States",2018,"10.1002/2017JD027194","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043721206&doi=10.1002%2f2017JD027194&partnerID=40&md5=8b0135690f49e87681b769a3d020d767","Many weather forecast and climate models simulate warm surface air temperature (T2m) biases over midlatitude continents during the summertime, especially over the Great Plains. We present here one of a series of papers from a multimodel intercomparison project (CAUSES: Cloud Above the United States and Errors at the Surface), which aims to evaluate the role of cloud, radiation, and precipitation biases in contributing to the T2m bias using a short-term hindcast approach during the spring and summer of 2011. Observations are mainly from the Atmospheric Radiation Measurement Southern Great Plains sites. The present study examines the contributions of surface energy budget errors. All participating models simulate too much net shortwave and longwave fluxes at the surface but with no consistent mean bias sign in turbulent fluxes over the Central United States and Southern Great Plains. Nevertheless, biases in the net shortwave and downward longwave fluxes as well as surface evaporative fraction (EF) are contributors to T2m bias. Radiation biases are largely affected by cloud simulations, while EF bias is largely affected by soil moisture modulated by seasonal accumulated precipitation and evaporation. An approximate equation based upon the surface energy budget is derived to further quantify the magnitudes of radiation and EF contributions to T2m bias. Our analysis ascribes that a large EF underestimate is the dominant source of error in all models with a large positive temperature bias, whereas an EF overestimate compensates for an excess of absorbed shortwave radiation in nearly all the models with the smallest temperature bias. ©2018. The Authors."
"57195136000;55963007800;23011078700;","Seasonal Sensitivity of the Hadley Cell and Cross-Hemispheric Responses to Diabatic Heating in an Idealized GCM",2018,"10.1002/2018GL077013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043712613&doi=10.1002%2f2018GL077013&partnerID=40&md5=74ee8e4e384b05990f6bb6da1ae28ba8","The seasonal sensitivity of the Hadley cell to localized diabatic forcing is studied using a dry idealized atmospheric general circulation model. Sensitivities are broadly consistent with Hadley cell responses in observations and climate models to El Niño–Southern Oscillation and global warming-like forcings. However, the exact seasonal sensitivity patterns highlight the importance of reducing the uncertainty in the size and position of expected anthropogenic forcings to understand how the atmospheric circulation will respond. The sensitivities reveal cross-hemispheric Hadley cell responses that project onto the eddy-driven jets and storm tracks. For summer hemisphere heating, the winter Hadley cell extent and jet latitude responses are highly correlated. For winter hemisphere heating, the summer Hadley cell extent and jet speed responses are highly correlated. These seasonal differences arise due to the contrast between the dominant winter Hadley cell and weaker summer Hadley cell. ©2018. American Geophysical Union. All Rights Reserved."
"8507259400;57201842899;6603369413;","Optimizing Precipitation Thresholds for Best Correlation Between Dry Lightning and Wildfires",2018,"10.1002/2017JD027639","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044439474&doi=10.1002%2f2017JD027639&partnerID=40&md5=13392fa6948db4cdf057ad9f13e2a6f0","This work examines how to adjust the definition of “dry lightning” in order to optimize the correlation between dry lightning flash count and the climatology of large (>400 km2) lightning-ignited wildfires over the contiguous United States (CONUS). The National Lightning Detection Network™ and National Centers for Environmental Prediction Stage IV radar-based, gauge-adjusted precipitation data are used to form climatic data sets. For a 13 year analysis period over CONUS, a correlation of 0.88 is found between annual totals of wildfires and dry lightning. This optimal correlation is found by defining dry lightning as follows: on a 0.1° hourly grid, a precipitation threshold of no more than 0.3 mm may accumulate during any hour over a period of 3–4 days preceding the flash. Regional optimized definitions vary. When annual totals are analyzed as done here, no clear advantage is found by weighting positive polarity cloud-to-ground (+CG) lightning differently than –CG lightning. The high variability of dry lightning relative to the precipitation and lightning from which it is derived suggests it would be an independent and useful climate indicator. ©2018. American Geophysical Union. All Rights Reserved."
"14045744500;25926762100;22635190100;13006055400;6508155070;7102266120;8977001000;6602504047;8397494800;7102425008;8922308700;8042408300;55713034800;55796504300;8349315600;7004485409;55802246600;36187387300;57001643600;7401936984;7403282069;57201123684;7402064802;7003582587;","Introduction to CAUSES: Description of Weather and Climate Models and Their Near-Surface Temperature Errors in 5 day Hindcasts Near the Southern Great Plains",2018,"10.1002/2017JD027199","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043460621&doi=10.1002%2f2017JD027199&partnerID=40&md5=5cedb4b46ba7a83315d2017177329cf2","We introduce the Clouds Above the United States and Errors at the Surface (CAUSES) project with its aim of better understanding the physical processes leading to warm screen temperature biases over the American Midwest in many numerical models. In this first of four companion papers, 11 different models, from nine institutes, perform a series of 5 day hindcasts, each initialized from reanalyses. After describing the common experimental protocol and detailing each model configuration, a gridded temperature data set is derived from observations and used to show that all the models have a warm bias over parts of the Midwest. Additionally, a strong diurnal cycle in the screen temperature bias is found in most models. In some models the bias is largest around midday, while in others it is largest during the night. At the Department of Energy Atmospheric Radiation Measurement Southern Great Plains (SGP) site, the model biases are shown to extend several kilometers into the atmosphere. Finally, to provide context for the companion papers, in which observations from the SGP site are used to evaluate the different processes contributing to errors there, it is shown that there are numerous locations across the Midwest where the diurnal cycle of the error is highly correlated with the diurnal cycle of the error at SGP. This suggests that conclusions drawn from detailed evaluation of models using instruments located at SGP will be representative of errors that are prevalent over a larger spatial scale. ©2018. Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland."
"55730541100;55783064400;21933618400;57200282476;7006377579;57189089842;37056101400;55554531900;9044746800;6602087140;7006728825;13403627400;12645353200;57195257572;7006837187;7006235542;","Aircraft and ground measurements of dust aerosols over the west African coast in summer 2015 during ICE-D and AER-D",2018,"10.5194/acp-18-3817-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044089537&doi=10.5194%2facp-18-3817-2018&partnerID=40&md5=64d9096bd33fd42a92fbbbb84c96d63c","During the summertime, dust from the Sahara can be efficiently transported westwards within the Saharan air layer (SAL). This can lead to high aerosol loadings being observed above a relatively clean marine boundary layer (MBL) in the tropical Atlantic Ocean. These dust layers can impart significant radiative effects through strong visible and IR light absorption and scattering, and can also have indirect impacts by altering cloud properties. The processing of the dust aerosol can result in changes in both direct and indirect radiative effects, leading to significant uncertainty in climate prediction in this region. During August 2015, measurements of aerosol and cloud properties were conducted off the coast of west Africa as part of the Ice in Cloud Experiment - Dust (ICE-D) and AERosol properties - Dust (AER-D) campaigns. Observations were obtained over a 4-week period using the UK Facility for Atmospheric Airborne Measurements (FAAM) BAe 146 aircraft based on Santiago Island, Cabo Verde. Ground-based observations were collected from Praia (14°57′ N, 23°29′W; 100 ma.s.l.), also located on Santiago Island. The dust in the SAL was mostly sampled in situ at altitudes of 2-4 km, and the potential dust age was estimated by backward trajectory analysis. The particle mass concentration (at diameter d = 0.1-20 μm) decreased with transport time. Mean effective diameter (Deff) for supermicron SAL dust (d = 1-20 μm) was found to be 5-6 μm regardless of dust age, whereas submicron Deff (d = 0.1-1 μm) showed a decreasing trend with longer transport. For the first time, an airborne laser-induced incandescence instrument (the single particle soot photometer - SP2) was deployed to measure the hematite content of dust. For the Sahel-influenced dust in the SAL, the observed hematite mass fraction of dust (FHm) was found to be anti-correlated with the single scattering albedo (SSA, λ = 550 nm, for particles d < 2:5 μm); as potential dust age increased from 2 to 7 days, FHm increased from 2.5 to 4.5 %, SSA decreased from 0.97 to 0.93 and the derived imaginary part (k) of the refractive index at 550 nm increased from 0.0015 to 0.0035. However, the optical properties of Sahara-influenced plumes (not influenced by the Sahel) were independent of dust age and hematite content with SSA∼0.95 and k ∼ 0.0028. This indicates that the absorbing component of dust may be source dependent, or that gravitational settling of larger particles may lead to a higher fraction of more absorbing clay-iron aggregates at smaller sizes. Mie calculation using the measured size distribution and size-resolved refractive indices of the absorbing components (black carbon and hematite) reproduces the measured SSA to within ±0.02 for SAL dust by assuming a goethite = hematite mass ratio of 2. Overall, hematite and goethite constituted 40-80% of the absorption for particles d < 2:5 μm, and black carbon (BC) contributed 10-37 %. This highlights the importance of size-dependent composition in determining the optical properties of dust and also the contribution from BC within dust plumes. © Author(s) 2018."
"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."
"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."
"55908305800;55750846900;57201158187;8561575700;36081093300;22836772900;13611337000;6603323589;7005776035;57202524778;55875542300;7403495552;7006749626;","Altimetry, gravimetry, GPS and viscoelastic modeling data for the joint inversion for glacial isostatic adjustment in Antarctica (ESA STSE Project REGINA)",2018,"10.5194/essd-10-493-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043598683&doi=10.5194%2fessd-10-493-2018&partnerID=40&md5=d0906a77879c104d49001332703ecd5f","The poorly known correction for the ongoing deformation of the solid Earth caused by glacial isostatic adjustment (GIA) is a major uncertainty in determining the mass balance of the Antarctic ice sheet from measurements of satellite gravimetry and to a lesser extent satellite altimetry. In the past decade, much progress has been made in consistently modeling ice sheet and solid Earth interactions; however, forward-modeling solutions of GIA in Antarctica remain uncertain due to the sparsity of constraints on the ice sheet evolution, as well as the Earth's rheological properties. An alternative approach towards estimating GIA is the joint inversion of multiple satellite data - namely, satellite gravimetry, satellite altimetry and GPS, which reflect, with different sensitivities, trends in recent glacial changes and GIA. Crucial to the success of this approach is the accuracy of the spacegeodetic data sets. Here, we present reprocessed rates of surface-ice elevation change (Envisat/Ice, Cloud,and land Elevation Satellite, ICESat; 2003-2009), gravity field change (Gravity Recovery and Climate Experiment, GRACE; 2003-2009) and bedrock uplift (GPS; 1995-2013). The data analysis is complemented by the forward modeling of viscoelastic response functions to disc load forcing, allowing us to relate GIA-induced surface displacements with gravity changes for different rheological parameters of the solid Earth. The data and modeling results presented here are available in the PANGAEA database (https://doi.org/10.1594/PANGAEA.875745). The data sets are the input streams for the joint inversion estimate of present-day ice-mass change and GIA, focusing on Antarctica. However, the methods, code and data provided in this paper can be used to solve other problems, such as volume balances of the Antarctic ice sheet, or can be applied to other geographical regions in. The case of the viscoelastic response functions. This paper presents the first of two contributions summarizing the work carried out within a European Space Agency funded study: Regional glacial isostatic adjustment and CryoSat elevation rate corrections in Antarctica (REGINA). © Author(s) 2018."
"6602390932;55830295500;56204562000;35519963800;55056533200;57217323583;6603023560;55920986400;42961129400;55339298600;55502994400;","The ESA GOME-Evolution ""climate"" water vapor product: A homogenized time series of H2O columns from GOME, SCIAMACHY, and GOME-2",2018,"10.5194/essd-10-449-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043579055&doi=10.5194%2fessd-10-449-2018&partnerID=40&md5=5ad31bfd014b127ebd3401d83012b8ba","We present time series of the global distribution of water vapor columns over more than 2 decades based on measurements from the satellite instruments GOME, SCIAMACHY, and GOME-2 in the red spectral range. A particular focus is the consistency amongst the different sensors to avoid jumps from one instrument to another. This is reached by applying robust and simple retrieval settings consistently. Potentially systematic effects due to differences in ground pixel size are avoided by merging SCIAMACHY and GOME-2 observations to GOME spatial resolution, which also allows for a consistent treatment of cloud effects. In addition, the GOME- 2 swath is reduced to that of GOME and SCIAMACHY to have consistent viewing geometries. Remaining systematic differences between the different sensors are investigated during overlap periods and are corrected for in the homogenized time series. The resulting ""Climate"" product v2.2 (https://doi.org/10.1594/ WDCC/GOME-EVL-water-vapor-clim-v2.2) allows the study of the temporal evolution of water vapor over the last 20 years on a global scale.. © Author(s) 2018."
"7006717176;57201153467;54788178800;53664297000;9248919400;35768617200;7006747377;7202607188;55826910100;7102011023;","A global space-based stratospheric aerosol climatology: 1979-2016",2018,"10.5194/essd-10-469-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043599399&doi=10.5194%2fessd-10-469-2018&partnerID=40&md5=36aa166f6dcea1e32f96402b878b745b","We describe the construction of a continuous 38-year record of stratospheric aerosol optical properties. The Global Space-based Stratospheric Aerosol Climatology, or GloSSAC, provided the input data to the construction of the Climate Model Intercomparison Project stratospheric aerosol forcing data set (1979-2014) and we have extended it through 2016 following an identical process. GloSSAC focuses on the Stratospheric Aerosol and Gas Experiment (SAGE) series of instruments through mid-2005, and on the Optical Spectrograph and InfraRed Imager System (OSIRIS) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data thereafter. We also use data from other space instruments and from ground-based, air, and balloon borne instruments to fill in key gaps in the data set. The end result is a global and gap-free data set focused on aerosol extinction coefficient at 525 and 1020 nm and other parameters on an ""as available"" basis. For the primary data sets, we developed a new method for filling the post-Pinatubo eruption data gap for 1991-1993 based on data from the Cryogenic Limb Array Etalon Spectrometer. In addition, we developed a new method for populating wintertime high latitudes during the SAGE period employing a latitude-equivalent latitude conversion process that greatly improves the depiction of aerosol at high latitudes compared to earlier similar efforts. We report data in the troposphere only when and where it is available. This is primarily during the SAGE II period except for the most enhanced part of the Pinatubo period. It is likely that the upper troposphere during Pinatubo was greatly enhanced over non-volcanic periods and that domain remains substantially under-characterized. We note that aerosol levels during the OSIRIS/CALIPSO period in the lower stratosphere at mid-and high latitudes is routinely higher than what we observed during the SAGE II period. While this period had nearly continuous low-level volcanic activity, it is possible that the enhancement in part reflects deficiencies in the data set. We also expended substantial effort to quality assess the data set and the product is by far the best we have produced. GloSSAC version 1.0 is available in netCDF format at the NASA Atmospheric Data Center at https://eosweb.larc.nasa.gov/. GloSSAC users should cite this paper and the data set DOI (https://doi.org/10.5067/GloSSAC-L3-V1.0). © 2018 Copernicus GmbH. All rights reserved."
"56389356400;12767251100;56016514800;6603873829;6602506180;35490828000;56118407000;24758974300;6603440546;35369402500;7004326742;7003627515;","Modelling the climate and surface mass balance of polar ice sheets using RACMO2 - Part 1: Greenland (1958-2016)",2018,"10.5194/tc-12-811-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043401211&doi=10.5194%2ftc-12-811-2018&partnerID=40&md5=0f73ac9ba4078dbbfd43a2c9e3b0b07f","We evaluate modelled Greenland ice sheet (GrIS) near-surface climate, surface energy balance (SEB) and surface mass balance (SMB) from the updated regional climate model RACMO2 (1958-2016). The new model version, referred to as RACMO2.3p2, incorporates updated glacier outlines, topography and ice albedo fields. Parameters in the cloud scheme governing the conversion of cloud condensate into precipitation have been tuned to correct inland snowfall underestimation: snow properties are modified to reduce drifting snow and melt production in the ice sheet percolation zone. The ice albedo prescribed in the updated model is lower at the ice sheet margins, increasing ice melt locally. RACMO2.3p2 shows good agreement compared to in situ meteorological data and point SEB/SMB measurements, and better resolves the spatial patterns and temporal variability of SMB compared with the previous model version, notably in the north-east, south-east and along the K-transect in south-western Greenland. This new model version provides updated, high-resolution gridded fields of the GrIS present-day climate and SMB, and will be used for projections of the GrIS climate and SMB in response to a future climate scenario in a forthcoming study. © Author(s) 2018."
"24734166800;24173372900;6603343811;7202746634;55897485300;49261186800;6603933756;36495529100;","Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in situ and satellite observations",2018,"10.5194/acp-18-3223-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043373813&doi=10.5194%2facp-18-3223-2018&partnerID=40&md5=e51b6b0b363bd14c234243f248c38318","Volcanic eruptions impact climate through the injection of sulfur dioxide (SO2), which is oxidized to form sulfuric acid aerosol particles that can enhance the stratospheric aerosol optical depth (SAOD). Besides large-magnitude eruptions, moderate-magnitude eruptions such as Kasatochi in 2008 and Sarychev Peak in 2009 can have a significant impact on stratospheric aerosol and hence climate. However, uncertainties remain in quantifying the atmospheric and climatic impacts of the 2009 Sarychev Peak eruption due to limitations in previous model representations of volcanic aerosol microphysics and particle size, whilst biases have been identified in satellite estimates of post-eruption SAOD. In addition, the 2009 Sarychev Peak eruption co-injected hydrogen chloride (HCl) alongside SO2, whose potential stratospheric chemistry impacts have not been investigated to date. We present a study of the stratospheric SO2-particle-HCl processing and impacts following Sarychev Peak eruption, using the Community Earth System Model version 1.0 (CESM1) Whole Atmosphere Community Climate Model (WACCM)-Community Aerosol and Radiation Model for Atmospheres (CARMA) sectional aerosol microphysics model (with no a priori assumption on particle size). The Sarychev Peak 2009 eruption injected 0.9ĝ€Tg of SO2 into the upper troposphere and lower stratosphere (UTLS), enhancing the aerosol load in the Northern Hemisphere. The post-eruption evolution of the volcanic SO2 in space and time are well reproduced by the model when compared to Infrared Atmospheric Sounding Interferometer (IASI) satellite data. Co-injection of 27ĝ€Ggĝ€†HCl causes a lengthening of the SO2 lifetime and a slight delay in the formation of aerosols, and acts to enhance the destruction of stratospheric ozone and mono-nitrogen oxides (NOx) compared to the simulation with volcanic SO2 only. We therefore highlight the need to account for volcanic halogen chemistry when simulating the impact of eruptions such as Sarychev on stratospheric chemistry. The model-simulated evolution of effective radius (reff) reflects new particle formation followed by particle growth that enhances reff to reach up to 0.2ĝ€μm on zonal average. Comparisons of the model-simulated particle number and size distributions to balloon-borne in situ stratospheric observations over Kiruna, Sweden, in August and September 2009, and over Laramie, USA, in June and November 2009 show good agreement and quantitatively confirm the post-eruption particle enhancement. We show that the model-simulated SAOD is consistent with that derived from the Optical Spectrograph and InfraRed Imager System (OSIRIS) when both the saturation bias of OSIRIS and the fact that extinction profiles may terminate well above the tropopause are taken into account. Previous modelling studies (involving assumptions on particle size) that reported agreement with (biased) post-eruption estimates of SAOD derived from OSIRIS likely underestimated the climate impact of the 2009 Sarychev Peak eruption. © Author(s) 2018."
"57198006594;26665602100;35546188200;","Aerosol indirect effects on summer precipitation in a regional climate model for the Euro-Mediterranean region",2018,"10.5194/angeo-36-321-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043369271&doi=10.5194%2fangeo-36-321-2018&partnerID=40&md5=7231784112748593b4fd59dea413b937","Aerosols affect atmospheric dynamics through their direct and semi-direct effects as well as through their effects on cloud microphysics (indirect effects). The present study investigates the indirect effects of aerosols on summer precipitation in the Euro-Mediterranean region, which is located at the crossroads of air masses carrying both natural and anthropogenic aerosols. While it is difficult to disentangle the indirect effects of aerosols from the direct and semi-direct effects in reality, a numerical sensitivity experiment is carried out using the Weather Research and Forecasting (WRF) model, which allows us to isolate indirect effects, all other effects being equal. The Mediterranean hydrological cycle has often been studied using regional climate model (RCM) simulations with parameterized convection, which is the approach we adopt in the present study. For this purpose, the Thompson aerosol-Aware microphysics scheme is used in a pair of simulations run at 50ĝ€̄km resolution with extremely high and low aerosol concentrations. An additional pair of simulations has been performed at a convection-permitting resolution (3.3ĝ€̄km) to examine these effects without the use of parameterized convection.
While the reduced radiative flux due to the direct effects of the aerosols is already known to reduce precipitation amounts, there is still no general agreement on the sign and magnitude of the aerosol indirect forcing effect on precipitation, with various processes competing with each other. Although some processes tend to enhance precipitation amounts, some others tend to reduce them. In these simulations, increased aerosol loads lead to weaker precipitation in the parameterized (low-resolution) configuration. The fact that a similar result is obtained for a selected area in the convection-permitting (high-resolution) configuration allows for physical interpretations. By examining the key variables in the model outputs, we propose a causal chain that links the aerosol effects on microphysics to their simulated effect on precipitation, essentially through reduction of the radiative heating of the surface and corresponding reductions of surface temperature, resulting in increased atmospheric stability in the presence of high aerosol loads. © 2018 Author(s)."
"16644246500;36992744000;7401945370;7201504886;35509639400;56520853700;","Radiative-convective equilibrium model intercomparison project",2018,"10.5194/gmd-11-793-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042845837&doi=10.5194%2fgmd-11-793-2018&partnerID=40&md5=8b81810be5bcaacc822b1d0c37b0572d","RCEMIP, an intercomparison of multiple types of models configured in radiative-convective equilibrium (RCE), is proposed. RCE is an idealization of the climate system in which there is a balance between radiative cooling of the atmosphere and heating by convection. The scientific objectives of RCEMIP are three-fold. First, clouds and climate sensitivity will be investigated in the RCE setting. This includes determining how cloud fraction changes with warming and the role of self-aggregation of convection in climate sensitivity. Second, RCEMIP will quantify the dependence of the degree of convective aggregation and tropical circulation regimes on temperature. Finally, by providing a common baseline, RCEMIP will allow the robustness of the RCE state across the spectrum of models to be assessed, which is essential for interpreting the results found regarding clouds, climate sensitivity, and aggregation, and more generally, determining which features of tropical climate a RCE framework is useful for. A novel aspect and major advantage of RCEMIP is the accessibility of the RCE framework to a variety of models, including cloud-resolving models, general circulation models, global cloud-resolving models, single-column models, and large-eddy simulation models. © Author(s) 2018."
"7201485519;7005056279;56575686800;","No access interactions between hydrological sensitivity, radiative cooling, stability, and low-level cloud amount feedback",2018,"10.1175/JCLI-D-16-0895.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041946426&doi=10.1175%2fJCLI-D-16-0895.1&partnerID=40&md5=7285f2fc205aee6c8ea6d475377b3aa5","Low-level cloud feedbacks vary in magnitude but are positive in most climate models, due to reductions in low-level cloud fraction. This study explores the impact of surface evaporation on low-level cloud fraction feedback by performing climate change experiments with the aquaplanet configuration of the HadGEM2-A climate model, forcing surface evaporation to increase at different rates in two ways. Forcing the evaporation diagnosed in the surface scheme to increase at 7% K-1 with warming (more than doubling the hydrological sensitivity) results in an increase in global mean low-level cloud fraction and a negative global cloud feedback, reversing the signs of these responses compared to the standard experiments. The estimated inversion strength (EIS) increases more rapidly in these surface evaporation forced experiments, which is attributed to additional latent heat release and enhanced warming of the free troposphere. Stimulating a 7% K-1 increase in surface evaporation via enhanced atmospheric radiative cooling, however, results in a weaker EIS increase compared to the standard experiments and a slightly stronger low-level cloud reduction. The low-level cloud fraction response is predicted better by EIS than surface evaporation across all experiments. This suggests that surface-forced increases in evaporation increase low-level cloud fraction mainly by increasing EIS. Additionally, the results herein show that increases in surface evaporation can have a very substantial impact on the rate of increase in radiative cooling with warming, by modifying the temperature and humidity structure of the atmosphere. This has implications for understanding the factors controlling hydrological sensitivity. © 2018 American Meteorological Society."
"57189358034;57194851498;23095483400;56879989100;57203053317;","Cirrus cloud properties as seen by the CALIPSO satellite and ECHAM-HAM global climate model",2018,"10.1175/JCLI-D-16-0608.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041958771&doi=10.1175%2fJCLI-D-16-0608.1&partnerID=40&md5=8d382de1138e5560c955f91f4e4ed2d8","Cirrus clouds impact the planetary energy balance and upper-tropospheric water vapor transport and are therefore relevant for climate. In this study cirrus clouds at temperatures colder than 240°C simulated by the ECHAM-Hamburg Aerosol Module (ECHAM-HAM) general circulation model are compared to Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite data. The model captures the general cloud cover pattern and reproduces the observed median ice water content within a factor of 2, while extinction is overestimated by about a factor of 3 as revealed by temperature-dependent frequency histograms. Two distinct types of cirrus clouds are found: in situ-formed cirrus dominating at temperatures colder than 255°C and liquid-origin cirrus dominating at temperatures warmer than 255°C. The latter cirrus form in anvils of deep convective clouds or by glaciation of mixed-phase clouds, leading to high ice crystal number concentrations. They are associated with extinction coefficients and ice water content of up to 1 km-1 and 0.1 gm-3, respectively, while the in situ-formed cirrus are associated with smaller extinction coefficients and ice water content. In situ-formed cirrus are nucleated either heterogeneously or homogeneously. The simulated homogeneous ice crystals are similar to liquid-origin cirrus, which are associated with high ice crystal number concentrations. On the contrary, heterogeneously nucleated ice crystals appear in smaller number concentrations. However, ice crystal aggregation and depositional growth smooth the differences between several formation mechanisms, making the attribution to a specific ice nucleation mechanism challenging. © 2018 American Meteorological Society."
"55286185400;6701752471;7005808242;50261552200;9939102400;55193344000;18435749300;57192468922;7103271625;7101823091;7004343004;12809675900;7402677913;6603396333;7103242280;57208462871;11939929300;7103206141;55418799600;57081464900;8733578200;35223590200;57208455668;7005884486;57189365144;7006003831;7006306835;56244473600;24528897900;23486734100;6508195621;57072934200;56744278700;34974672900;6508175197;6603171355;8733579000;57194420030;54992767300;55437450100;57201664908;7003802133;6602864692;8733579800;12244212300;","The GFDL Global Atmosphere and Land Model AM4.0/LM4.0: 2. Model Description, Sensitivity Studies, and Tuning Strategies",2018,"10.1002/2017MS001209","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045639367&doi=10.1002%2f2017MS001209&partnerID=40&md5=5311a49bcbba682ece208b3951e3ca9d","In Part 2 of this two-part paper, documentation is provided of key aspects of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode has been provided in Part 1. Part 2 provides documentation of key components and some sensitivities to choices of model formulation and values of parameters, highlighting the convection parameterization and orographic gravity wave drag. The approach taken to tune the model's clouds to observations is a particular focal point. Care is taken to describe the extent to which aerosol effective forcing and Cess sensitivity have been tuned through the model development process, both of which are relevant to the ability of the model to simulate the evolution of temperatures over the last century when coupled to an ocean model. © 2018. The Authors."
"56506403700;35578854200;55370337800;56732511400;6506802023;","Measurements from a cold climate site in Canada: Boundary conditions and verification methods for CFD icing models for wind turbines",2018,"10.1016/j.coldregions.2017.12.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040625060&doi=10.1016%2fj.coldregions.2017.12.007&partnerID=40&md5=a6ba0abcc15b26cf2a8176ede8647486","This study presents an analysis of icing measurements from a cold climate site in Canada. The collected dataset provides a set of inlet boundary conditions suitable for the modelling of icing events.The study o attempts to quantify the uncertainties associated with the established boundary conditions. To construct the dataset, effort was put indetermining the icing specific atmospheric variables. In particular, two methods for retrieving the cloud liquid water content and the associated droplet size were used. Furthermore, ice growth was measured on a cup anemometer support arm to provide an experimental comparison. From image analysis the ice growth was observed. The resulting dataset can provide inlet boundary conditions for simulating an icing event and additionally a set of data used for verification purposes. © 2017 Elsevier B.V."
"7004364155;7403931916;7102651635;12803465300;6506827279;7006783796;56493740900;25633865300;24322892500;56850170100;36466972400;","Impact of ice cloud microphysics on satellite cloud retrievals and broadband flux radiative transfer model calculations",2018,"10.1175/JCLI-D-17-0426.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041945557&doi=10.1175%2fJCLI-D-17-0426.1&partnerID=40&md5=40381c5eb112298f430814b05fc351cf","Ice cloud particles exhibit a range of shapes and sizes affecting a cloud's single-scattering properties. Because they cannot be inferred from passive visible/infrared imager measurements, assumptions about the bulk single-scattering properties of ice clouds are fundamental to satellite cloud retrievals and broadband radiative flux calculations. To examine the sensitivity to ice particle model assumptions, three sets of models are used in satellite imager retrievals of ice cloud fraction, thermodynamic phase, optical depth, effective height, and particle size, and in top-of-atmosphere (TOA) and surface broadband radiative flux calculations. The three ice particle models include smooth hexagonal ice columns (SMOOTH), roughened hexagonal ice columns, and a two-habit model (THM) comprising an ensemble of hexagonal columns and 20-element aggregates. While the choice of ice particle model has a negligible impact on daytime cloud fraction and thermodynamic phase, the global mean ice cloud optical depth retrieved from THM is smaller than from SMOOTH by 2.3 (28%), and the regional root-mean-square difference (RMSD) is 2.8 (32%). Effective radii derived from THM are 3.9 μm (16%) smaller than SMOOTH values and the RMSD is 5.2 μm (21%). In contrast, the regional RMSD in TOA and surface flux between THM and SMOOTH is only 1% in the shortwave and 0.3% in the longwave when a consistent ice particle model is assumed in the cloud property retrievals and forward radiative transfer model calculations. Consequently, radiative fluxes derived using a consistent ice particle model assumption throughout provide a more robust reference for climate model evaluation compared to ice cloud property retrievals. © 2018 American Meteorological Society."
"36931958000;6602075440;7401666571;9434771700;35098801000;","Influence of dimethyl sulfide on the carbon cycle and biological production",2018,"10.1007/s10533-018-0430-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042605209&doi=10.1007%2fs10533-018-0430-5&partnerID=40&md5=d3cb7ef63f82d7a6ae6e553968b46725","Dimethyl sulfide (DMS) is a significant source of marine sulfate aerosol and plays an important role in modifying cloud properties. Fully coupled climate simulations using dynamic marine ecosystem and DMS calculations are conducted to estimate DMS fluxes under various climate scenarios and to examine the sign and strength of phytoplankton-DMS-climate feedbacks for the first time. Simulation results show small differences in the DMS production and emissions between pre-industrial and present climate scenarios, except for some areas in the Southern Ocean. There are clear changes in surface ocean DMS concentrations moving into the future, and they are attributable to changes in phytoplankton production and competition driven by complex spatially varying mechanisms. Comparisons between parallel simulations with and without DMS fluxes into the atmosphere show significant differences in marine ecosystems and physical fields. Without DMS, the missing subsequent aerosol indirect effects on clouds and radiative forcing lead to fewer clouds, more solar radiation, and a much warmer climate. Phaeocystis, a uniquely efficient organosulfur producer with a growth advantage under cooler climate states, can benefit from producing the compound through cooling effects of DMS in the climate system. Our results show a tight coupling between the sulfur and carbon cycles. The ocean carbon uptake declines without DMS emissions to the atmosphere. The analysis indicates a weak positive phytoplankton-DMS-climate feedback at the global scale, with large spatial variations driven by individual autotrophic functional groups and complex mechanisms. The sign and strength of the feedback vary with climate states and phytoplankton groups. This highlights the importance of a dynamic marine ecosystem module and the sulfur cycle mechanism in climate projections. © 2018, The Author(s)."
"55286185400;6701752471;7005808242;50261552200;9939102400;55193344000;18435749300;57192468922;7103271625;7101823091;7004343004;12809675900;7402677913;6603396333;7103242280;57208462871;11939929300;7103206141;55418799600;57081464900;8733578200;35223590200;57208455668;7005884486;57189365144;7006003831;7006306835;56244473600;24528897900;23486734100;6508195621;57072934200;56744278700;34974672900;6508175197;6603171355;8733579000;57194420030;54992767300;55437450100;57201664908;7003802133;6602864692;8733579800;12244212300;","The GFDL Global Atmosphere and Land Model AM4.0/LM4.0: 1. Simulation Characteristics With Prescribed SSTs",2018,"10.1002/2017MS001208","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045647450&doi=10.1002%2f2017MS001208&partnerID=40&md5=08864aa3e0a4a081bc9a91e4a93b2916","In this two-part paper, a description is provided of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). This version, with roughly 100 km horizontal resolution and 33 levels in the vertical, contains an aerosol model that generates aerosol fields from emissions and a “light” chemistry mechanism designed to support the aerosol model but with prescribed ozone. In Part 1, the quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode—with prescribed sea surface temperatures (SSTs) and sea-ice distribution—is described and compared with previous GFDL models and with the CMIP5 archive of AMIP simulations. The model's Cess sensitivity (response in the top-of-atmosphere radiative flux to uniform warming of SSTs) and effective radiative forcing are also presented. In Part 2, the model formulation is described more fully and key sensitivities to aspects of the model formulation are discussed, along with the approach to model tuning. © 2018. The Authors."
"56439201600;24765842200;6701636816;7402383878;23485990000;7006728825;","A projected decrease in lightning under climate change",2018,"10.1038/s41558-018-0072-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041931890&doi=10.1038%2fs41558-018-0072-6&partnerID=40&md5=c3124183f2dbbca43afc07ba03a45540","Lightning strongly influences atmospheric chemistry 1-3, and impacts the frequency of natural wildfires 4 . Most previous studies project an increase in global lightning with climate change over the coming century 1,5-7, but these typically use parameterizations of lightning that neglect cloud ice fluxes, a component generally considered to be fundamental to thunderstorm charging 8 . As such, the response of lightning to climate change is uncertain. Here, we compare lightning projections for 2100 using two parameterizations: the widely used cloud-top height (CTH) approach 9, and a new upward cloud ice flux (IFLUX) approach 10 that overcomes previous limitations. In contrast to the previously reported global increase in lightning based on CTH, we find a 15% decrease in total lightning flash rate with IFLUX in 2100 under a strong global warming scenario. Differences are largest in the tropics, where most lightning occurs, with implications for the estimation of future changes in tropospheric ozone and methane, as well as differences in their radiative forcings. These results suggest that lightning schemes more closely related to cloud ice and microphysical processes are needed to robustly estimate future changes in lightning and atmospheric composition. © 2018 The Author(s)."
"16246205000;55738957800;","The Roles of Convection Parameterization in the Formation of Double ITCZ Syndrome in the NCAR CESM: I. Atmospheric Processes",2018,"10.1002/2017MS001191","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044291252&doi=10.1002%2f2017MS001191&partnerID=40&md5=9fd5724ce4d0fc3a5be35d432b3dd0c8","Several improvements are implemented in the Zhang-McFarlane (ZM) convection scheme to investigate the roles of convection parameterization in the formation of double intertropical convergence zone (ITCZ) bias in the NCAR CESM1.2.1. It is shown that the prominent double ITCZ biases of precipitation, sea surface temperature (SST), and wind stress in the standard CESM1.2.1 are largely eliminated in all seasons with the use of these improvements in convection scheme. This study for the first time demonstrates that the modifications of convection scheme can eliminate the double ITCZ biases in all seasons, including boreal winter and spring. Further analysis shows that the elimination of the double ITCZ bias is achieved not by improving other possible contributors, such as stratus cloud bias off the west coast of South America and cloud/radiation biases over the Southern Ocean, but by modifying the convection scheme itself. This study demonstrates that convection scheme is the primary contributor to the double ITCZ bias in the CESM1.2.1, and provides a possible solution to the long-standing double ITCZ problem. The atmospheric model simulations forced by observed SST show that the original ZM convection scheme tends to produce double ITCZ bias in high SST scenario, while the modified convection scheme does not. The impact of changes in each core component of convection scheme on the double ITCZ bias in atmospheric model is identified and further investigated. © 2018. The Authors."
"56942554300;36538539800;55802355600;8511991900;7202048112;35792776400;55624488227;7202010686;","Fine-scale application of WRF-CAM5 during a dust storm episode over East Asia: Sensitivity to grid resolutions and aerosol activation parameterizations",2018,"10.1016/j.atmosenv.2017.12.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038242085&doi=10.1016%2fj.atmosenv.2017.12.014&partnerID=40&md5=3bf2341d33c1fa8ef6fcf9587573f125","An advanced online-coupled meteorology and chemistry model WRF-CAM5 has been applied to East Asia using triple-nested domains at different grid resolutions (i.e., 36-, 12-, and 4-km) to simulate a severe dust storm period in spring 2010. Analyses are performed to evaluate the model performance and investigate model sensitivity to different horizontal grid sizes and aerosol activation parameterizations and to examine aerosol-cloud interactions and their impacts on the air quality. A comprehensive model evaluation of the baseline simulations using the default Abdul-Razzak and Ghan (AG) aerosol activation scheme shows that the model can well predict major meteorological variables such as 2-m temperature (T2), water vapor mixing ratio (Q2), 10-m wind speed (WS10) and wind direction (WD10), and shortwave and longwave radiation across different resolutions with domain-average normalized mean biases typically within ±15%. The baseline simulations also show moderate biases for precipitation and moderate-to-large underpredictions for other major variables associated with aerosol-cloud interactions such as cloud droplet number concentration (CDNC), cloud optical thickness (COT), and cloud liquid water path (LWP) due to uncertainties or limitations in the aerosol-cloud treatments. The model performance is sensitive to grid resolutions, especially for surface meteorological variables such as T2, Q2, WS10, and WD10, with the performance generally improving at finer grid resolutions for those variables. Comparison of the sensitivity simulations with an alternative (i.e., the Fountoukis and Nenes (FN) series scheme) and the default (i.e., AG scheme) aerosol activation scheme shows that the former predicts larger values for cloud variables such as CDNC and COT across all grid resolutions and improves the overall domain-average model performance for many cloud/radiation variables and precipitation. Sensitivity simulations using the FN series scheme also have large impacts on radiations, T2, precipitation, and air quality (e.g., decreasing O3) through complex aerosol-radiation-cloud-chemistry feedbacks. The inclusion of adsorptive activation of dust particles in the FN series scheme has similar impacts on the meteorology and air quality but to lesser extent as compared to differences between the FN series and AG schemes. Compared to the overall differences between the FN series and AG schemes, impacts of adsorptive activation of dust particles can contribute significantly to the increase of total CDNC (∼45%) during dust storm events and indicate their importance in modulating regional climate over East Asia. © 2017 Elsevier Ltd"
"6701354598;6506833087;","Estimating the Number of Cloud Layers through Radiosonde Data from Russian Aerological Stations for 1964–2014",2018,"10.3103/S1068373918030032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044986929&doi=10.3103%2fS1068373918030032&partnerID=40&md5=37aec5b2a9126baebadf031241a33aec","Radiosonde data are used for the period of 1964–2014 and the method that determines the boundaries and cloud amount based on the profiles of temperature and humidity [23]; long-period statistical characteristics are computed for the cloud layer number for different altitude ranges from the ground to 10 km. The study is performed for the Russian aerological stations located at different latitudes and climate zones. To specify the spatiotemporal features of the atmosphere layering into cloud layers and cloudless layers between them, the estimates of monthly mean, seasonal mean, and annual mean values of cloud layer number as well as of their standard deviations are computed, and the amplitude of their variations is determined. The results qualitatively agree with the data of aircraft-based sounding of the atmosphere as well as with the data of radars and experiments with free balloons. © 2018, Allerton Press, Inc."
"55816227500;56722821200;15755995900;7003666669;56162305900;","An evaluation of marine boundary layer cloud property simulations in the Community Atmosphere Model using satellite observations: Conventional subgrid parameterization versus CLUBB",2018,"10.1175/JCLI-D-17-0277.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043699733&doi=10.1175%2fJCLI-D-17-0277.1&partnerID=40&md5=7080df4a2f3bf37e3b46ada4fdd669dc","This paper presents a satellite-observation-based evaluation of the marine boundary layer (MBL) cloud properties from two Community Atmosphere Model, version 5 (CAM5), simulations, one with the standard parameterization schemes (CAM5-Base) and the other with the Cloud Layers Unified by Binormals scheme (CAM5-CLUBB). When comparing the direct model outputs, the authors find that CAM5-CLUBB produces more MBL clouds, a smoother transition from stratocumulus to cumulus, and a tighter correlation between in-cloud water and cloud fraction than CAM5-Base. In the model-to-observation comparison using the COSP satellite simulators, the authors find that both simulations capture the main features and spatial patterns of the observed cloud fraction from MODIS and shortwave cloud radiative forcing (SWCF) from CERES. However, CAM5-CLUBB suffers more than CAM5-Base from a problem that can be best summarized as ""undetectable"" clouds (i.e., a significant fraction of simulated MBL clouds are thinner than the MODIS detection threshold). This issue leads to a smaller COSP-MODIS cloud fraction and a weaker SWCF in CAM5-CLUBB than the observations and also CAM5-Base in the tropical descending regions. Finally, the authors compare modeled radar reflectivity with CloudSat observations and find that both simulations, especially CAM5-CLUBB, suffer from an excessive drizzle problem. Further analysis reveals that the subgrid precipitation enhancement factors in CAM5-CLUBB are unrealistically large, which makes MBL clouds precipitate too excessively, and in turn results in too many undetectable thin clouds. © 2018 American Meteorological Society."
"7003631214;57201735822;6603752490;6603680545;","Long-Term Variability of UV Irradiance in the Moscow Region according to Measurement and Modeling Data",2018,"10.1134/S0001433818020056","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045999633&doi=10.1134%2fS0001433818020056&partnerID=40&md5=1bdf141ccd00501782b3c714f655710c","We have found distinct long-period changes in erythemal UV radiation (Qer) characterized by a pronounced decrease at the end of the 1970s and a statistically significant positive trend of more than 5%/10 years since 1979 over the territory of the Moscow region according to the measurements and reconstruction model. The positive Qer trend is shown to be associated mainly with a decrease in the effective cloud amount and total ozone content (TOC). Due to these variations, UV resources have significantly changed in spring for the population with the most vulnerable skin type I, which means a transition from the UV optimum to UV moderate excess conditions. The simulation experiments using the INM-RSHU chemistry climate model (CCM) for several scenarios with and without anthropogenic factors have revealed that the variations in the anthropogenic emissions of halogens have the most significant impact on the variability of TOC and Qer. Among natural factors, noticeable effects are observed due to volcanic aerosol. The calculations of the cloud transmittance of Qer are generally consistent with the measurements; however, they do not reproduce the observed value of the positive trend. © 2018, Pleiades Publishing, Ltd."
"57201299489;7202089880;57188867135;56717253400;57201297217;57205914978;57201301091;8271769900;7202588306;55576725800;","Estimation of daily average downward shortwave radiation over Antarctica",2018,"10.3390/rs10030422","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044192591&doi=10.3390%2frs10030422&partnerID=40&md5=7ab82e980bc148f509e07e416b4a4d05","Surface shortwave (SW) irradiation is the primary driving force of energy exchange in the atmosphere and land interface. The global climate is profoundly influenced by irradiation changes due to the special climatic condition in Antarctica. Remote-sensing retrieval can offer only the instantaneous values in an area, whilst daily cycle and average values are necessary for further studies and applications, including climate change, ecology, and land surface process. When considering the large values of and small diurnal changes of solar zenith angle and cloud coverage, we develop two methods for the temporal extension of remotely sensed downward SW irradiance over Antarctica. The first one is an improved sinusoidal method, and the second one is an interpolation method based on cloud fraction change. The instantaneous irradiance data and cloud products are used in both methods to extend the diurnal cycle, and obtain the daily average value. Data from South Pole and Georg von Neumayer stations are used to validate the estimated value. The coefficient of determination (R2) between the estimated daily averages and the measured values based on the first method is 0.93, and the root mean square error (RMSE) is 32.21 W/m2 (8.52%). As for the traditional sinusoidal method, the R2 and RMSE are 0.68 and 70.32 W/m2 (18.59%), respectively The R2 and RMSE of the second method are 0.96 and 25.27 W/m2 (6.98%), respectively. These values are better than those of the traditional linear interpolation (0.79 and 57.40 W/m2 (15.87%)). © 2018 by the authors."
"57201075918;55801070100;7403564495;7402721790;57200702127;7404829395;57191702441;7005973015;","Application and Evaluation of an Explicit Prognostic Cloud-Cover Scheme in GRAPES Global Forecast System",2018,"10.1002/2017MS001234","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043351269&doi=10.1002%2f2017MS001234&partnerID=40&md5=49a86b06e4070ddde8e3d7a773d411cf","An explicit prognostic cloud-cover scheme (PROGCS) is implemented into the Global/Regional Assimilation and Prediction System (GRAPES) for global middle-range numerical weather predication system (GRAPES_GFS) to improve the model performance in simulating cloud cover and radiation. Unlike the previous diagnostic cloud-cover scheme (DIAGCS), PROGCS considers the formation and dissipation of cloud cover by physically connecting it to the cumulus convection and large-scale stratiform condensation processes. Our simulation results show that clouds in mid-high latitudes arise mainly from large-scale stratiform condensation processes, while cumulus convection and large-scale condensation processes jointly determine cloud cover in low latitudes. Compared with DIAGCS, PROGCS captures more consistent vertical distributions of cloud cover with the observations from Atmospheric Radiation Measurements (ARM) program at the Southern Great Plains (SGP) site and simulates more realistic diurnal cycle of marine stratocumulus with the ERA-Interim reanalysis data. The low, high, and total cloud covers that are determined via PROGCS appear to be more realistic than those simulated via DIAGCS when both are compared with satellite retrievals though the former maintains slight negative biases. In addition, the simulations of outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) from PROGCS runs have been considerably improved as well, resulting in less biases in radiative heating rates at heights below 850 hPa and above 400 hPa of GRAPES_GFS. Our results indicate that a prognostic method of cloud-cover calculation has significant advantage over the conventional diagnostic one, and it should be adopted in both weather and climate simulation and forecast. © 2018. The Authors."
"57197713127;12794067600;9233714800;56503083100;","Characteristics of cloud occurrence using ceilometer measurements and its relationship to precipitation over Seoul",2018,"10.1016/j.atmosres.2017.10.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034060693&doi=10.1016%2fj.atmosres.2017.10.010&partnerID=40&md5=92c123de9c01b7630ce5fbe02ed64d2f","Clouds are an important component of the atmosphere that affects both climate and weather, however, their contributions can be very difficult to determine. Ceilometer measurements can provide high resolution information on atmospheric conditions such as cloud base height (CBH) and vertical frequency of cloud occurrence (CVF). This study presents the first comprehensive analysis of CBH and CVF derived using Vaisala CL51 ceilometers at two urban stations in Seoul, Korea, during a three-year period from January 2014 to December 2016. The average frequency of cloud occurrence detected by the ceilometers is 54.3%. It is found that the CL51 is better able to capture CBH as compared to another ceilometer CL31 at a nearby meteorological station because it could detect high clouds more accurately. Frequency distributions for CBH up to 13,000 m providing detailed vertical features with 500-m interval show 55% of CBHs below 2 km for aggregated CBHs. A bimodal frequency distribution was observed for three-layers CBHs. A monthly variation of CVF reveals that frequency concentration of lower clouds is found in summer and winter, and higher clouds more often detected in spring and autumn. Monthly distribution features of cloud occurrence and precipitation are depending on seasons and it might be easy to define their relationship due to higher degree of variability of precipitation than cloud occurrence. However, a fluctuation of cloud occurrence frequency in summer is similar to precipitation in trend, whereas clouds in winter are relatively frequent but precipitation is not accompanied. In addition, recent decrease of summer precipitation could be mostly explained by a decrease of cloud occurrence. Anomalous precipitation recorded sometimes is considerably related to corresponding cloud occurrence. The diurnal and daily variations of CBH and CVF from ceilometer observations and the analysis of microwave radiometer measurements for two typical cloudiness cases are also reviewed in parallel. This analysis in finer temporal scale exhibits that utilization of ground-based observations together could help to analyze the cloud behaviors. © 2017 Elsevier B.V."
"57200577402;57193210111;14041876800;","Investigation of drought-vulnerable regions in North Korea using remote sensing and cloud computing climate data",2018,"10.1007/s10661-018-6466-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041727053&doi=10.1007%2fs10661-018-6466-0&partnerID=40&md5=dcaa83b1aa7074a02317ca40a5ef1b19","Drought is one of the most severe natural disasters in the world and leads to serious challenges that affect both the natural environment and human societies. North Korea (NK) has frequently suffered from severe and prolonged droughts since the second half of the twentieth century. These droughts affect the growing conditions of agricultural crops, which have led to food shortages in NK. However, it is not easy to obtain ground data because NK is one of the most closed-off societies in the world. In this situation, remote sensing (RS) techniques and cloud computing climate data (CCCD) can be used for drought monitoring in NK. RS-derived drought indices and CCCD were used to determine the drought-vulnerable regions in the spring season in NK. After the results were compared and discussed, the following conclusions were derived: (1) 10.0% of the total area of NK is estimated to be a drought-vulnerable region. The most susceptible regions to drought appear in the eastern and western coastal regions, far from BaekDu-DaeGan (BDDG), while fewer drought regions are found near BDDG and the Nahngrim Mountains. The drought-vulnerable regions are the coastal regions of South Hamgyong Province, North Hamgyong Province, South Pyongan Province, and South Hwanghae Province. The latter region is the food basket of NK. (2) In terms of land cover, the drought-vulnerable regions mainly consisted of croplands and mixed forest. © 2018, Springer International Publishing AG, part of Springer Nature."
"57194285910;6506340624;8633783900;12787547600;6602087140;55357516200;8606857600;","Do differences in future sulfate emission pathways matter for near-term climate? A case study for the Asian monsoon",2018,"10.1007/s00382-017-3726-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019543352&doi=10.1007%2fs00382-017-3726-6&partnerID=40&md5=d7ac8a8e674e25c7fd2aefa122ad2762","Anthropogenic aerosols could dominate over greenhouse gases in driving near-term hydroclimate change, especially in regions with high present-day aerosol loading such as Asia. Uncertainties in near-future aerosol emissions represent a potentially large, yet unexplored, source of ambiguity in climate projections for the coming decades. We investigated the near-term sensitivity of the Asian summer monsoon to aerosols by means of transient modelling experiments using HadGEM2-ES under two existing climate change mitigation scenarios selected to have similar greenhouse gas forcing, but to span a wide range of plausible global sulfur dioxide emissions. Increased sulfate aerosols, predominantly from East Asian sources, lead to large regional dimming through aerosol-radiation and aerosol-cloud interactions. This results in surface cooling and anomalous anticyclonic flow over land, while abating the western Pacific subtropical high. The East Asian monsoon circulation weakens and precipitation stagnates over Indochina, resembling the observed southern-flood-northern-drought pattern over China. Large-scale circulation adjustments drive suppression of the South Asian monsoon and a westward extension of the Maritime Continent convective region. Remote impacts across the Northern Hemisphere are also generated, including a northwestward shift of West African monsoon rainfall induced by the westward displacement of the Indian Ocean Walker cell, and temperature anomalies in northern midlatitudes linked to propagation of Rossby waves from East Asia. These results indicate that aerosol emissions are a key source of uncertainty in near-term projection of regional and global climate; a careful examination of the uncertainties associated with aerosol pathways in future climate assessments must be highly prioritised. © 2017, The Author(s)."
"57190731566;35226469400;55741373000;57213396721;7102700868;7406294260;","A lookup-table-based approach to estimating surface solar irradiance from geostationary and polar-orbiting satellite data",2018,"10.3390/rs10030411","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044186706&doi=10.3390%2frs10030411&partnerID=40&md5=fdb69d00148bafea3679c4ba29451c74","Incoming surface solar irradiance (SSI) is essential for calculating Earth's surface radiation budget and is a key parameter for terrestrial ecological modeling and climate change research. Remote sensing images from geostationary and polar-orbiting satellites provide an opportunity for SSI estimation through directly retrieving atmospheric and land-surface parameters. This paper presents a new scheme for estimating SSI from the visible and infrared channels of geostationary meteorological and polar-orbiting satellite data. Aerosol optical thickness and cloud microphysical parameters were retrieved from Geostationary Operational Environmental Satellite (GOES) system images by interpolating lookup tables of clear and cloudy skies, respectively. SSI was estimated using pre-calculated offline lookup tables with different atmospheric input data of clear and cloudy skies. The lookup tables were created via the comprehensive radiative transfer model, Santa Barbara Discrete Ordinate Radiative Transfer (SBDART), to balance computational efficiency and accuracy. The atmospheric attenuation effects considered in our approach were water vapor absorption and aerosol extinction for clear skies, while cloud parameters were the only atmospheric input for cloudy-sky SSI estimation. The approach was validated using one-year pyranometer measurements from seven stations in the SURFRAD (SURFace RADiation budget network). The results of the comparison for 2012 showed that the estimated SSI agreed with ground measurements with correlation coefficients of 0.94, 0.69, and 0.89 with a bias of 26.4 W/m2, -5.9 W/m2, and 14.9 W/m2 for clear-sky, cloudy-sky, and all-sky conditions, respectively. The overall root mean square error (RMSE) of instantaneous SSI was 80.0 W/m2 (16.8%), 127.6 W/m2 (55.1%), and 99.5 W/m2 (25.5%) for clear-sky, cloudy-sky (overcast sky and partly cloudy sky), and all-sky (clear-sky and cloudy-sky) conditions, respectively. A comparison with other state-of-the-art studies suggests that our proposed method can successfully estimate SSI with a maximum improvement of an RMSE of 24 W/m2. The clear-sky SSI retrieval was sensitive to aerosol optical thickness, which was largely dependent on the diurnal surface reflectance accuracy. Uncertainty in the pre-defined horizontal visibility for 'clearest sky' will eventually lead to considerable SSI retrieval error. Compared to cloud effective radius, the retrieval error of cloud optical thickness was a primary factor that determined the SSI estimation accuracy for cloudy skies. Our proposed method can be used to estimate SSI for clear and one-layer cloud sky, but is not suitable for multi-layer clouds overlap conditions as a lower-level cloud cannot be detected by the optical sensor when a higher-level cloud has a higher optical thickness. © 2018 by the authors."
"55963007800;7401836526;","Linking hadley circulation and storm tracks in a conceptual model of the atmospheric energy balance",2018,"10.1175/JAS-D-17-0098.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044667600&doi=10.1175%2fJAS-D-17-0098.1&partnerID=40&md5=527de5c505463bd3f2737e1e905cc4ef","Midlatitude storm tracks shift in response to climate change and natural climate variations such as El Niño, but the dynamical mechanisms controlling these shifts are not well established. This paper develops an energy balance model that shows how shifts of the Hadley cell terminus and changes of the meridional energy flux out of the Hadley cell can drive shifts of storm tracks, identified as extrema of the atmospheric meridional eddy energy flux. The distance between the Hadley cell terminus and the storm tracks is primarily controlled by the energy flux out of the Hadley cell. Because tropical forcings alone can modify the Hadley cell terminus, they can also shift extratropical storm tracks, as demonstrated through simulations with an idealized GCM. Additionally, a strengthening of the meridional temperature gradient at the terminus and hence of the energy flux out of the Hadley cell can reduce the distance between the Hadley cell terminus and the storm tracks, enabling storm-track shifts that do not parallel shifts of the Hadley cell terminus. Thus, with the aid of the energy balance model and supporting GCM simulations, a closed theory of storm-track shifts emerges. © 2018 American Meteorological Society."
"57195549023;55918418100;","Effects of Polar Indirect Circulation on Superrotation and Multiple Equilibrium in Long-Term AGCM Experiments With an Idealized Venus-Like Forcing: Sensitivity to Horizontal Resolution and Initial Condition",2018,"10.1002/2017JE005385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045516074&doi=10.1002%2f2017JE005385&partnerID=40&md5=fad12ff9ae53607e0655ca2111194a6f","A simplified model setup has been used in atmospheric general circulation models (AGCMs), to clarify the fluid dynamical process of terrestrial planets. In the present work, the research aim is to ascertain the dynamical effects of polar indirect circulation on superrotation and multiple equilibrium states in Venus-like planets. The model setup previously used for Venus AGCM intercomparison is applied to the Model for Interdisciplinary Research On Climate AGCM, and the horizontal resolution and initial conditions are altered in the long-term experiments. The structures of general circulation and planetary-scale waves in the T42 (Truncation wave number 42) experiment are similar to those in the T63 experiment. In the presence of the polar indirect circulation, the superrotational flow weakens in the cloud layer and its momentum is transported toward the lower atmosphere at high latitudes. In contrast, in the T21 experiment, because the polar indirect circulation is not fully resolved, the vertical momentum transport due to the indirect circulation is ineffective in the lower atmosphere, and thus, the cloud top superrotational flow becomes greater than those in the higher-resolution experiments. The multiple equilibrium states caused by different initial zonal flows appear in the T21 experiments, although they are not seen in the experiments of T42 and higher. Thus, the polar indirect circulation in the Gierasch-Rossow-Williams mechanism weakens the superrotational flow in the cloud layer and breaks the steady state multiplicity of the general circulation. ©2018. The Authors."
"57200800656;7403475773;","An investigation into the energy performance gap between the predicted and measured output of photovoltaic systems using dynamic simulation modelling software-A case study",2018,"10.1093/ijlct/ctx016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042458160&doi=10.1093%2fijlct%2fctx016&partnerID=40&md5=979d62a157d9e4d7eb415e86f339eceb","The use of solar energy can help reduce CO2 emissions and dependency on fossil fuels, and using Solar Photovoltaic (PV) systems to generate electricity is a popular route to decarbonisation in the UK. To help achieve the targets set out in the Climate Change Act, building service consultants often use EDSL Tas, a dynamic modelling software, to simulate PV systems and integrate the energy output results into the overall energy performance of a building. There is, however, a clear performance gap between the measured and predicted energy output. There are many causes for the potential deviation of results, although the most influential in relation to energy performance is the use of weather data, future climate change, adverse weather conditions and environmental factors affecting the PV array. The results through a case study indicated an 8.6% higher measured energy output from the installed PV system although the performance gap has little detrimental effect regarding achieving Building Regulation compliance, but could lead to the unreasonable design of the PV system and inappropriate use of capital investment. Further simulation using projected future weather data from several different climate change scenarios was undertaken. 2020, 2050 and 2080 with low, medium and high emission scenarios indicated that the PV array would increase energy output by up to 5% by 2080 compared with using current weather data, indicating a rise in PV energy output in relation to increased CO2 emissions. This is due to a projected reduction in cloud cover and increased downward shortwave radiation. © The Author 2017."
"56651680700;7202157381;7801602398;","Dynamic downscaling over western Himalayas: Impact of cloud microphysics schemes",2018,"10.1016/j.atmosres.2017.10.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033491808&doi=10.1016%2fj.atmosres.2017.10.007&partnerID=40&md5=2b168a8f21387a148f7db7c8c93ad698","Due to lack of observation data in the region of inhomogeneous terrain of the Himalayas, detailed climate of Himalayas is still unknown. Global reanalysis data are too coarse to represent the hydroclimate over the region with sharp orography gradient in the western Himalayas. In the present study, dynamic downscaling of the European Centre for Medium-Range Weather Forecast (ECMWF) Reanalysis-Interim (ERA-I) dataset over the western Himalayas using high-resolution Weather Research and Forecast (WRF) model has been carried out. Sensitivity studies have also been carried out using convection and microphysics parameterization schemes. The WRF model simulations have been compared against ERA-I and available station observations. Analysis of the results suggests that the WRF model has simulated the hydroclimate of the region well. It is found that in the simulations that the impact of convection scheme is more during summer months than in winter. Examination of simulated results using various microphysics schemes reveal that the WRF single-moment class-6 (WSM6) scheme simulates more precipitation on the upwind region of the high mountain than that in the Morrison and Thompson schemes during the winter period. Vertical distribution of various hydrometeors shows that there are large differences in mixing ratios of ice, snow and graupel in the simulations with different microphysics schemes. The ice mixing ratio in Morrison scheme is more than WSM6 above 400 hPa. The Thompson scheme favors formation of more snow than WSM6 or Morrison schemes while the Morrison scheme has more graupel formation than other schemes. © 2017 Elsevier B.V."
"35572026100;7005729142;6506385754;","Determination of the ice particle size distributions using observations as the integrated constraints",2018,"10.1175/JAS-D-17-0145.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044671114&doi=10.1175%2fJAS-D-17-0145.1&partnerID=40&md5=7cfe0c4eedc4bd25c2ce5b29c79de6d3","The possibility is suggested of estimating particle size distributions (PSD) solely based on the bulk quantities of the hydrometeors. The method, inspired by the maximum entropy principle, can be applied to any predefined general PSD form as long as the number of the free parameters is equal to or less than that of the bulk quantities available. As long as an adopted distribution is ""physically based,"" these bulk characterizations can recover a fairly accurate PSD estimate. This method is tested for ice particle measurements from the Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The total particle number, total mass, and mean size are taken as bulk quantities. The gamma distribution and two distributions obtained under the maximum entropy principle by taking the size and the particle mass, respectively, as a restriction variable are adopted for fit. The fitting error for the two maximum entropy-based distributions is comparable to that of a standard direct fitting method with the gamma distribution. The same procedure works almost equally well when the mean size is removed from the constraint, especially for an exponential distribution. The results suggest that the total particle number and the total mass of the hydrometeors are sufficient for determining the PSD to a reasonable accuracy when a ""physically based"" distribution is assumed. In addition to the in situ cloud measurements, remote sensing measurements such as those from radar as well as satellite can be adopted as physical constraints. Possibilities of exploiting different types of measurements should be further pursued. © 2018 American Meteorological Society."
"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."
"57209630149;57202404435;7402179527;55656837900;","Increase of surface solar irradiance across East China related to changes in aerosol properties during the past decade",2018,"10.1088/1748-9326/aaa35a","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048213735&doi=10.1088%2f1748-9326%2faaa35a&partnerID=40&md5=e5080885634ffa32977d500ae9757b0d","Previously, it was widely documented that an overall decrease in surface solar radiation occurred in China at least until 2005, in contrast to the general background of 'global brightening'. Increased anthropogenic aerosol emissions were speculated to be the source of the reduction. In this study, we extend the trend analysis to the most recent decade from 2005-2015 and find that surface solar radiation has shifted from 'dimming' to 'brightening' over East China, with the largest increase over the northeast and southeast parts. Meanwhile, satellite and ground observation both indicate a reduction in aerosol optical depth (AOD) during the same period, whereas no significant trends in cloud amount show up. Detailed analysis using co-located radiation and aerosol observation at the XiangHe station in North China suggests that both AOD and single scattering albedo (SSA) changes contribute to the radiation trends. AOD reduction contributes to the increase of direct solar radiation, also decreasing the diffuse radiation, while the increase of SSA serves to increase the diffuse fraction. Simple calculations using a radiative transfer model confirm that the two effects combined explain changes in the global solar radiation and its components effectively. Our results have implications for potential climate effects with the reduction of China's aerosol emissions, and the necessity to monitor aerosol composition in addition to its loading. © 2018 The Author(s). Published by IOP Publishing Ltd."
"54080527200;","Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers",2018,"10.1016/j.wace.2017.12.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043397427&doi=10.1016%2fj.wace.2017.12.001&partnerID=40&md5=b914698dcbbac1a071f2ad2c4d1389e5","The extremes of month-specific spatial temperature differences were studied for a first time in the high-latitude city of Lahti and its surroundings in southern Finland. During the 2-year observation period (6/14–5/16), the largest momentary temperature difference, 11.1 °C, was detected in February, and the smallest, 6.2 °C, in April. The impacts of various environmental factors during the extreme situations were estimated by site-specific analysis of the warmest and coldest observation sites and a stepwise multiple linear regression model including all the 8 observation sites. The extreme temperature differences were characterised by inversions especially in winter and spring, the warmest site being the hill-top location in Kivistönmäki. In summer the role of urban heating was more apparent, and the temperature was the highest in the relatively low-lying city centre. In autumn the heating impact of the relatively warm Lake Vesijärvi caused the largest temperature differences with harbour as the warmest site. The weather during all of the momentary extreme situations was calm and in the majority of the situations also clear. The impact of cloud cover was less critical than that of wind speed in reducing spatial temperature differences. The momentary extreme situations existed at night or at dawn, with one exception: only in January, during the cold weather period dominated by high pressure, the delayed break of inversion in the vicinity of Lake Vesijärvi caused the extreme temperature difference to exist in the afternoon, reflecting for its part the substantial stabilising impact of seasonal ice cover on Lake Vesijärvi. © 2017 The Author"
"57200162560;13806362800;7003859790;7402587163;","Anomalously low δ18O values of high-latitude Permo-Triassic paleosol siderite",2018,"10.1016/j.palaeo.2017.11.062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039997881&doi=10.1016%2fj.palaeo.2017.11.062&partnerID=40&md5=ac33a15e591e8fc596ee298e903a093d","The most severe extinction in Earth history occurred during a time of extreme climate change, caused in part by a massive release of carbon into the atmosphere. Isotopic measurements of siderite occurring in paleosols during intervals of global warming suggest high-latitude depletions in δ18O of precipitation, often attributed to an amplified hydrologic cycle. Here, Late Permian and Early Triassic paleosol siderite from Alaska, Antarctica, eastern Australia, Siberia, and South Africa indicate similar or greater meridional gradients in siderite δ18O compared to other past warm intervals. An isotope-tracer-enabled version of the Global Environmental and Ecological Simulation of Interactive Systems (GENESIS) general circulation model (GCM) was used to compare to siderite δ18O data. The model, when deriving siderite δ18O at a specified paleoatmospheric CO2 concentration of 12.7 × the preindustrial atmospheric level (PAL), matches a small subset of relatively less depleted high-latitude siderites but does not produce the conditions necessary to explain the most depleted siderite δ18O values. Siderite has been thought to record mean annual precipitation δ18O, though this study suggests that many may not. A seasonal bias, where siderite growth occurs in the summertime in wetlands that receive most of their recharge from melting winter precipitation, may be responsible. GENESIS indicates soil moisture recharge during the spring ahead of the rainy season for high-latitude Permo-Triassic (PT) siderite localities that reach below freezing winter temperatures. Drainage from high altitude regions throughout the growing season may also be responsible. Biological cloud feedbacks and monsoon-related amount effects are not likely the cause for low siderite δ18O because the enrichment of water vapor δ18O associated with warming is too significant. © 2017 Elsevier B.V."
"6508247200;56031936200;6701313057;56183254400;55550221200;57201152310;7007149890;35230947600;6505914340;57210417092;7102467545;57209097944;7003890331;","Climatic Constraints on Growth Rate and Geochemistry (Sr/Ca and U/Ca) of the Coral Siderastrea stellata in the Southwest Equatorial Atlantic (Rocas Atoll, Brazil)",2018,"10.1002/2017GC007365","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043599802&doi=10.1002%2f2017GC007365&partnerID=40&md5=f83c5c82f666bcdf6658e67222ddfbcf","Although relatively rare compared to similar latitudes in the Pacific or Indian Oceans, massive coral colonies are present in the Tropical/Equatorial Southwestern Atlantic Ocean. However, detailed geochemical compositions of these corals are still largely unknown. In this work, we present growth rates, Sr/Ca, and U/Ca ratios of the coral colony (Siderastrea stellata) sampled at Rocas Atoll, off the Brazilian coast. These variables are primarily affected by sea surface temperature (SST) at seasonal scale, and by wind stress at interannual scale, these results represent a broad new finding. A lower significance at the interannual time scale between Sr/Ca and U/Ca with respect to SST is attributed to the low SST amplitude closed to Equator. An investigation on the dependence of coral growth rates with respect to the “cloud shading effect” promoted by the Intertropical Convergence Zone (ITCZ) does not show significant influence. Additionally, rain seems to act on local geochemistry of Sr/Ca ratios and growth rate at the decadal scale. © 2018. American Geophysical Union. All Rights Reserved."
"26536657700;7402545511;57192671220;","New method for estimating daily global solar radiation over sloped topography in China",2018,"10.1007/s00376-017-6243-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041005597&doi=10.1007%2fs00376-017-6243-y&partnerID=40&md5=f5b661cb61f57533fc16b925642035e2","A new scheme for the estimation of daily global solar radiation over sloped topography in China is developed based on the Iqbal model C and MODIS cloud fraction. The effects of topography are determined using a digital elevation model. The scheme is tested using observations of solar radiation at 98 stations in China, and the results show that the mean absolute bias error is 1.51 MJ m−2 d−1 and the mean relative absolute bias error is 10.57%. Based on calculations using this scheme, the distribution of daily global solar radiation over slopes in China on four days in the middle of each season (15 January, 15 April, 15 July and 15 October 2003) at a spatial resolution of 1 km × 1 km are analyzed. To investigate the effects of topography on global solar radiation, the results determined in four mountains areas (Tianshan, Kunlun Mountains, Qinling, and Nanling) are discussed, and the typical characteristics of solar radiation over sloped surfaces revealed. In general, the new scheme can produce reasonable characteristics of solar radiation distribution at a high spatial resolution in mountain areas, which will be useful in analyses of mountain climate and planning for agricultural production. © 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."
"37028496100;7405365321;7004563395;8511057500;","Creating a seamless 1 km resolution daily land surface temperature dataset for urban and surrounding areas in the conterminous United States",2018,"10.1016/j.rse.2017.12.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038838239&doi=10.1016%2fj.rse.2017.12.010&partnerID=40&md5=b41b5a03b77721d06e4dd75934bb195d","High spatiotemporal land surface temperature (LST) datasets are increasingly needed in a variety of fields such as ecology, hydrology, meteorology, epidemiology, and energy systems. Moderate Resolution Imaging Spectroradiometer (MODIS) daily LST is one of such high spatiotemporal datasets that are widely used. But, it has a large amount of missing values primarily because of clouds, shadows, and other atmospheric conditions. Gapfilling the missing values is an important approach to create seamless high spatiotemporal LST datasets. However, current gapfilling methods have limitations in terms of accuracy and efficiency to assemble the data over large areas (e.g., national and continental levels). In this study, we developed a 3-step hybrid method by integrating daily merging (gapfilling missing values at one overpass using values at the other three overpasses each day), spatiotemporal gapfilling (estimating missing values based on values of their spatial and temporal neighbors), and temporal interpolation (gapfilling missing values based on values of their neighboring days), to create a seamless high spatiotemporal LST dataset using the four daily LST observations from the two MODIS instruments on Terra and Aqua satellites. We applied this method in urban and surrounding areas in the conterminous U.S. in 2010. The evaluation of the gapfilled LST product indicates its root mean squared error (RMSE) to be 3.3 K for mid-daytime (1:30 pm) and 2.7 K for mid-nighttime (1:30 am) observations. The method can be easily extended to other years and regions and is also applicable to other satellite products for large areas. This seamless daily (mid-daytime and mid-nighttime) LST product with 1 km spatial resolution is of great value for studying urban climate (e.g., quantifying surface urban heat island intensity, creating seamless high spatiotemporal air temperature dataset) and the related impacts on people (e.g., health and mortality), ecosystems (e.g., phenology), and energy systems (e.g., building energy use). © 2017 Elsevier Inc."
"16043821500;23012169500;24479205400;57200210737;56364107000;23977679300;25621038300;55906607500;","Disaggregation of SMOS soil moisture over West Africa using the Temperature and Vegetation Dryness Index based on SEVIRI land surface parameters",2018,"10.1016/j.rse.2017.12.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040231426&doi=10.1016%2fj.rse.2017.12.036&partnerID=40&md5=334a9b0eeee059e554aab07db75fe2de","The overarching objective of this study was to produce a disaggregated SMOS Soil Moisture (SM) product using land surface parameters from a geostationary satellite in a region covering a diverse range of ecosystem types. SEVIRI data at 15 min temporal resolution were used to derive the Temperature and Vegetation Dryness Index (TVDI) that served as SM proxy within the disaggregation process. West Africa (3°N 26°W; 28°N 26°E) was selected as a case study as it presents both an important North-South climate gradient and a diverse range of ecosystem types. The main challenge was to set up a methodology applicable over a large area that overcomes the constraints of SMOS (low spatial resolution) and TVDI (requires similar atmospheric forcing and triangular shape formed when plotting morning rise temperature versus fraction of vegetation cover) in order to produce a 0.05° resolution disaggregated SMOS SM product at the sub-continental scale. Consistent cloud cover appeared as one of the main constraints for deriving TVDI, especially during the rainy season and in the southern parts of the region and a large adjustment window (105 × 105 SEVIRI pixels) was therefore deemed necessary. Both the original and the disaggregated SMOS SM products described well the seasonal dynamics observed at six locations of in situ observations. However, there was an overestimation in both products for sites in the humid southern regions; most likely caused by the presence of forest. Both TVDI and the associated disaggregated SM product were found to be highly sensitive to algorithm input parameters; especially for conditions of high fraction of vegetation cover. Additionally, seasonal dynamics in TVDI did not follow the seasonal patterns of SM. Still, its spatial heterogeneity was found to be a good proxy for disaggregating SMOS SM data; main river networks and spatial patterns of SM extremes (i.e. droughts and floods) not seen in the original SMOS SM product were revealed in the disaggregated SM product for a test case of July–September 2012. The disaggregation methodology thereby successfully increased the spatial resolution of SMOS SM, with potential application for local drought/flood monitoring of importance for the livelihood of the population of West Africa. © 2018 Elsevier Inc."
"56603873300;7202941773;55470017900;16550482700;55366522200;6602824724;","A new MODIS C6 dark target and Deep Blue merged aerosol product on a 3 km spatial grid",2018,"10.3390/rs10030463","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044242072&doi=10.3390%2frs10030463&partnerID=40&md5=d4da3db0b5200496ceda9c6b9b305320","In Moderate Resolution Imaging Spectroradiometer (MODIS) Collection (C6) aerosol products, the Dark Target (DT) and Deep Blue (DB) algorithms provide aerosol optical depth (AOD) observations at 3 km (DT3K) and 10 km (DT10K), and at 10 km resolution (DB10K), respectively. In this study, the DB10K is resampled to 3 km grid (DB3K) using the nearest neighbor interpolation technique and merged with DT3K to generate a new DT and DB merged aerosol product (DTB3K) on a 3 km grid using Simplified Merge Scheme (SMS). The goal is to supplement DB10K with high-resolution information over dense vegetation regions where DT3K is susceptible to error. SMS is defined as ""an average of the DT3K and DB3K AOD retrievals or the available one with the highest quality flag"". The DT3K and DTB3K AOD retrievals are validated from 2008 to 2012 against cloud-screened and quality-assured AOD from 19 AERONET sites located in Europe. Results show that the percentage of DTB3K retrievals within the expected error (EE = ± (0.05 + 20%)) and data counts are increased by 40% and 11%, respectively, and the root mean square error and the mean bias are decreased by 26% and 54%, respectively, compared to the DT3K retrievals. These results suggest that the DTB3K product is a robust improvement over DT3K alone, and can be used operationally for air quality and climate-related studies as a high-resolution supplement to the current MODIS product suite. © 2018 by the authors."
"56402112700;9036557400;57201291990;57200517230;23491844400;15725936000;","Classification and mapping of paddy rice by combining Landsat and SAR time series data",2018,"10.3390/rs10030447","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044229783&doi=10.3390%2frs10030447&partnerID=40&md5=cf14f0ed9e630967d13125e962905ec7","Rice is an important food resource, and the demand for rice has increased as population has expanded. Therefore, accurate paddy rice classification and monitoring are necessary to identify and forecast rice production. Satellite data have been often used to produce paddy rice maps with more frequent update cycle (e.g., every year) than field surveys. Many satellite data, including both optical and SAR sensor data (e.g., Landsat, MODIS, and ALOS PALSAR), have been employed to classify paddy rice. In the present study, time series data from Landsat, RADARSAT-1, and ALOS PALSAR satellite sensors were synergistically used to classify paddy rice through machine learning approaches over two different climate regions (sites A and B). Six schemes considering the composition of various combinations of input data by sensor and collection date were evaluated. Scheme 6 that fused optical and SAR sensor time series data at the decision level yielded the highest accuracy (98.67% for site A and 93.87% for site B). Performance of paddy rice classification was better in site A than site B, which consists of heterogeneous land cover and has low data availability due to a high cloud cover rate. This study also proposed Paddy Rice Mapping Index (PMI) considering spectral and phenological characteristics of paddy rice. PMI represented well the spatial distribution of paddy rice in both regions. Google Earth Engine was adopted to produce paddy rice maps over larger areas using the proposed PMI-based approach. © 2018 by the authors."
"56909883500;54963014000;56541819600;55657150600;7006555714;6603214045;","Article multitemporal SAR data and 2D hydrodynamic model flood scenario dynamics assessment",2018,"10.3390/ijgi7030105","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044504540&doi=10.3390%2fijgi7030105&partnerID=40&md5=64b25b74e56c8b7522201fe0c2c8501e","The increasing number of floods and the severity of their consequences, which is caused by phenomena, such as climate change and uncontrolled urbanization, create a growing need to develop operational procedures and tools for accurate and timely flood mapping and management. Synthetic Aperture Radar (SAR), with its day, night, and cloud-penetrating capacity, has proven to be a very useful source of information during calibration of hydrodynamic models considered indispensable tools for near real-time flood forecasting and monitoring. The paper begins with the analysis of radar signatures of temporal series of SAR data, by exploiting the short revisit time of the images that are provided by the Cosmo-SkyMed constellation of four satellites, in combination with a Digital Elevation Model for the extraction of flood extent and spatially distributed water depth in a flat area with complex topography during a flood event. These SAR-based hazard maps were then used to perform a bi-dimensional hydraulic model calibration on the November 2010 flood event at the mouth of the Bradano River in Basilicata, Italy. Once the best fit between flood predictions of hydrodynamic models was identified and the efficacy of SAR data in correcting hydrodynamic inconsistencies with regard to reliable assessment of flood extent and water-depth maps was shown by validation with the December 2013 Bradano River event. Based on calibration and validation results, the paper aims to show how the combination of the time series of Synthetic Aperture Radar (SAR) and Digital Elevation Model (DEM) derived water-depth maps with the data from the hydrodynamic model can provide valuable information for flood dynamics monitoring in a flat area with complex topography. Future research should focus on the integration and implementation of the semi-automatic proposed method in an operational system for near real-time flood management. © 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."
"57189708763;55729812300;55953611600;55888297700;55234835700;56038261200;56506978100;55696622200;56050004800;55277716700;57211236643;","Long-term annual mapping of four cities on different continents by applying a deep information learning method to Landsat data",2018,"10.3390/rs10030471","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044202715&doi=10.3390%2frs10030471&partnerID=40&md5=792d91035cbea02feab05c2569963d83","Urbanization is a substantial contributor to anthropogenic environmental change, and often occurs at a rapid pace that demands frequent and accurate monitoring. Time series of satellite imagery collected at fine spatial resolution using stable spectral bands over decades are most desirable for this purpose. In practice, however, temporal spectral variance arising from variations in atmospheric conditions, sensor calibration, cloud cover, and other factors complicates extraction of consistent information on changes in urban land cover. Moreover, the construction and application of effective training samples is time-consuming, especially at continental and global scales. Here, we propose a new framework for satellite-based mapping of urban areas based on transfer learning and deep learning techniques. We apply this method to Landsat observations collected during 1984-2016 and extract annual records of urban areas in four cities in the temperate zone (Beijing, New York, Melbourne, andMunich). The method is trained using observations of Beijing collected in 1999, and then used to map urban areas in all target cities for the entire 1984-2016 period. The method addresses two central challenges in long term detection of urban change: temporal spectral variance and a scarcity of training samples. First, we use a recurrent neural network to minimize seasonal urban spectral variance. Second, we introduce an automated transfer strategy tomaximize information gain fromlimited training samples when applied to new target cities in similar climate zones. Compared with other state-of-the-art methods, our method achieved comparable or even better accuracy: the average change detection accuracy during 1984-2016 is 89% for Beijing, 94% for New York, 93% forMelbourne, and 89% forMunich, and the overall accuracy of single-year urban maps is approximately 96 ± 3% among the four target cities. The results demonstrate the practical potential and suitability of the proposed framework. The method is a promising tool for detecting urban change in massive remote sensing data sets with limited training data. © 2018 by the authors."
"56375050900;56374986500;55914512600;57217456518;57214142405;57200517897;","Modeling of tropospheric NO2 column over different climatic zones and land use/land cover types in South Asia",2018,"10.1016/j.jastp.2018.01.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041454649&doi=10.1016%2fj.jastp.2018.01.022&partnerID=40&md5=d98fb8d6661059529356495dde3d6b88","We have applied regression analyses for the modeling of tropospheric NO2 (tropo-NO2) as the function of anthropogenic nitrogen oxides (NOx) emissions, aerosol optical depth (AOD), and some important meteorological parameters such as temperature (Temp), precipitation (Preci), relative humidity (RH), wind speed (WS), cloud fraction (CLF) and outgoing long-wave radiation (OLR) over different climatic zones and land use/land cover types in South Asia during October 2004–December 2015. Simple linear regression shows that, over South Asia, tropo-NO2 variability is significantly linked to AOD, WS, NOx, Preci and CLF. Also zone-5, consisting of tropical monsoon areas of eastern India and Myanmar, is the only study zone over which all the selected parameters show their influence on tropo-NO2 at statistical significance levels. In stepwise multiple linear modeling, tropo-NO2 column over landmass of South Asia, is significantly predicted by the combination of RH (standardized regression coefficient, β = − 49), AOD (β = 0.42) and NOx (β = 0.25). The leading predictors of tropo-NO2 columns over zones 1–5 are OLR, AOD, Temp, OLR, and RH respectively. Overall, as revealed by the higher correlation coefficients (r), the multiple regressions provide reasonable models for tropo-NO2 over South Asia (r = 0.82), zone-4 (r = 0.90) and zone-5 (r = 0.93). The lowest r (of 0.66) has been found for hot semi-arid region in northwestern Indus-Ganges Basin (zone-2). The highest value of β for urban area AOD (of 0.42) is observed for megacity Lahore, located in warm semi-arid zone-2 with large scale crop-residue burning, indicating strong influence of aerosols on the modeled tropo-NO2 column. A statistical significant correlation (r = 0.22) at the 0.05 level is found between tropo-NO2 and AOD over Lahore. Also NOx emissions appear as the highest contributor (β = 0.59) for modeled tropo-NO2 column over megacity Dhaka. © 2018 Elsevier Ltd"
"24168479200;57195236002;57195236023;57206835701;56158622800;55087038900;","Midlatitude Cirrus Clouds at the SACOL Site: Macrophysical Properties and Large-Scale Atmospheric States",2018,"10.1002/2017JD027724","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043359525&doi=10.1002%2f2017JD027724&partnerID=40&md5=0b3f1dae6c7af2b4b91db0a14332ba70","Two-year observations of a Ka-band Zenith Radar at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) are used to document the midlatitude cirrus cloud macroproperties. Generally, cirrus occurs 41.6% of the observation time and most frequently appear at about 7.2 km above ground level. The cirrus macroproperties are strongly coupled with large-scale atmospheric states; thus, its occurrence and location over the SACOL have significant seasonal variations. A k-mean clustering method is used to classify cirrus into four distinct regimes without a prior knowledge about the meteorological process. Contrasting to the different cirrus physical properties in each regime, the cirrus event of each regime has a distinct seasonal distribution and the synoptic conditions from the ERA-Interim reanalysis responsible for each cirrus regime are also quite different. Since global climate models typically overestimate cirrus cloud thickness due to inadequate parameterization or coarse grid resolution, we examined the probability density functions of large-scale vertical velocity associated with each cirrus regime and the relationship between cirrus thickness and vertical velocity. It is found that the differences of the vertical velocity probability density functions among the cirrus regimes are as distinct as their macroproperties and a significant correlation exists between cirrus thickness and the vertical velocity, although the large-scale vertical motion is nearly as likely to be descending as ascending when cirrus clouds are observed. This may imply that large-scale vertical velocity can be used to constrain the variations of cirrus thickness simulated by global climate models. ©2018. American Geophysical Union. All Rights Reserved."
"23486734100;16645242800;7103206141;55437450100;","Equilibrium Climate Sensitivity Obtained From Multimillennial Runs of Two GFDL Climate Models",2018,"10.1002/2017JD027885","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042084409&doi=10.1002%2f2017JD027885&partnerID=40&md5=61710ed0ec260d1293c64b76c1281b8e","Equilibrium climate sensitivity (ECS), defined as the long-term change in global mean surface air temperature in response to doubling atmospheric CO2, is usually computed from short atmospheric simulations over a mixed layer ocean, or inferred using a linear regression over a short-time period of adjustment. We report the actual ECS from multimillenial simulations of two Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models (GCMs), ESM2M, and CM3 of 3.3 K and 4.8 K, respectively. Both values are ~1 K higher than estimates for the same models reported in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change obtained by regressing the Earth's energy imbalance against temperature. This underestimate is mainly due to changes in the climate feedback parameter (−α) within the first century after atmospheric CO2 has stabilized. For both GCMs it is possible to estimate ECS with linear regression to within 0.3 K by increasing CO2 at 1% per year to doubling and using years 51–350 after CO2 is constant. We show that changes in −α differ between the two GCMs and are strongly tied to the changes in both vertical velocity at 500 hPa (ω500) and estimated inversion strength that the GCMs experience during the progression toward the equilibrium. This suggests that while cloud physics parametrizations are important for determining the strength of −α, the substantially different atmospheric state resulting from a changed sea surface temperature pattern may be of equal importance. ©2018. American Geophysical Union. All Rights Reserved."
"57196369879;7004372110;55641786300;6602410438;57195422828;55916149100;25027021800;","The dynamical core of the Aeolus 1.0 statistical-dynamical atmosphere model: Validation and parameter optimization",2018,"10.5194/gmd-11-665-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042672779&doi=10.5194%2fgmd-11-665-2018&partnerID=40&md5=df1836f81d88ba0b4d8852eff55b9878","We present and validate a set of equations for representing the atmosphere's large-scale general circulation in an Earth system model of intermediate complexity (EMIC). These dynamical equations have been implemented in Aeolus 1.0, which is a statistical-dynamical atmosphere model (SDAM) and includes radiative transfer and cloud modules (Coumou et al., 2011; Eliseev et al., 2013). The statistical dynamical approach is computationally efficient and thus enables us to perform climate simulations at multimillennia timescales, which is a prime aim of our model development. Further, this computational efficiency enables us to scan large and high-dimensional parameter space to tune the model parameters, e.g., for sensitivity studies.
Here, we present novel equations for the large-scale zonal-mean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0.
We optimize the dynamical core parameter values by tuning all relevant dynamical fields to ERA-Interim reanalysis data (1983-2009) forcing the dynamical core with prescribed surface temperature, surface humidity and cumulus cloud fraction. We test the model's performance in reproducing the seasonal cycle and the influence of the El Niño-Southern Oscillation (ENSO). We use a simulated annealing optimization algorithm, which approximates the global minimum of a high-dimensional function.
With non-tuned parameter values, the model performs reasonably in terms of its representation of zonal-mean circulation, planetary waves and storm tracks. The simulated annealing optimization improves in particular the model's representation of the Northern Hemisphere jet stream and storm tracks as well as the Hadley circulation.
The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications. © Author(s) 2018."
"7201472576;57190384098;","Characterization of AVHRR global cloud detection sensitivity based on CALIPSO-CALIOP cloud optical thickness information: Demonstration of results based on the CM SAF CLARA-A2 climate data record",2018,"10.5194/amt-11-633-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041909609&doi=10.5194%2famt-11-633-2018&partnerID=40&md5=7442b855b4fc52d1660d2fe165efd115","The sensitivity in detecting thin clouds of the cloud screening method being used in the CM SAF cloud, albedo and surface radiation data set from AVHRR data (CLARA-A2) cloud climate data record (CDR) has been evaluated using cloud information from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard the CALIPSO satellite. The sensitivity, including its global variation, has been studied based on collocations of Advanced Very High Resolution Radiometer (AVHRR) and CALIOP measurements over a 10-year period (2006-2015). The cloud detection sensitivity has been defined as the minimum cloud optical thickness for which 50ĝ€% of clouds could be detected, with the global average sensitivity estimated to be 0.225. After using this value to reduce the CALIOP cloud mask (i.e. clouds with optical thickness below this threshold were interpreted as cloud-free cases), cloudiness results were found to be basically unbiased over most of the globe except over the polar regions where a considerable underestimation of cloudiness could be seen during the polar winter. The overall probability of detecting clouds in the polar winter could be as low as 50ĝ€% over the highest and coldest parts of Greenland and Antarctica, showing that a large fraction of optically thick clouds also remains undetected here. The study included an in-depth analysis of the probability of detecting a cloud as a function of the vertically integrated cloud optical thickness as well as of the cloud's geographical position. Best results were achieved over oceanic surfaces at mid- to high latitudes where at least 50ĝ€% of all clouds with an optical thickness down to a value of 0.075 were detected. Corresponding cloud detection sensitivities over land surfaces outside of the polar regions were generally larger than 0.2 with maximum values of approximately 0.5 over the Sahara and the Arabian Peninsula. For polar land surfaces the values were close to 1 or higher with maximum values of 4.5 for the parts with the highest altitudes over Greenland and Antarctica. It is suggested to quantify the detection performance of other CDRs in terms of a sensitivity threshold of cloud optical thickness, which can be estimated using active lidar observations. Validation results are proposed to be used in Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulation Package (COSP) simulators for cloud detection characterization of various cloud CDRs from passive imagery."
"55575258400;57205867148;35561911800;36705143500;","Internal Variability and Disequilibrium Confound Estimates of Climate Sensitivity From Observations",2018,"10.1002/2017GL076468","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042496642&doi=10.1002%2f2017GL076468&partnerID=40&md5=a77312046ff01d830948365be98a0e4d","An emerging literature suggests that estimates of equilibrium climate sensitivity (ECS) derived from recent observations and energy balance models are biased low because models project more positive climate feedback in the far future. Here we use simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to show that across models, ECS inferred from the recent historical period (1979–2005) is indeed almost uniformly lower than that inferred from simulations subject to abrupt increases in CO2 radiative forcing. However, ECS inferred from simulations in which sea surface temperatures are prescribed according to observations is lower still. ECS inferred from simulations with prescribed sea surface temperatures is strongly linked to changes to tropical marine low clouds. However, feedbacks from these clouds are a weak constraint on long-term model ECS. One interpretation is that observations of recent climate changes constitute a poor direct proxy for long-term sensitivity. ©2018. American Geophysical Union. All Rights Reserved."
"55717074000;55542833500;","Sensitivity of Homogeneous Ice Nucleation to Aerosol Perturbations and Its Implications for Aerosol Indirect Effects Through Cirrus Clouds",2018,"10.1002/2017GL076721","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041800618&doi=10.1002%2f2017GL076721&partnerID=40&md5=9acea77feb0fd42af018d33575d5b938","The magnitude and sign of anthropogenic aerosol impacts on cirrus clouds through ice nucleation are still very uncertain. In this study, aerosol sensitivity (ηα), defined as the sensitivity of the number concentration (Ni) of ice crystals formed from homogeneous ice nucleation to aerosol number concentration (Na), is examined based on simulations from a cloud parcel model. The model represents the fundamental process of ice crystal formation that results from homogeneous nucleation. We find that the geometric dispersion (σ) of the aerosol size distribution used in the model is a key factor for ηα. For a monodisperse size distribution, ηα is close to zero in vertical updrafts (V < 50 cm s−1) typical of cirrus clouds. However, ηα increases to 0.1–0.3 (i.e., Ni increases by a factor of 1.3–2.0 for a tenfold increase in Na) if aerosol particles follow lognormal size distributions with a σ of 1.6–2.3 in the upper troposphere. By varying the input aerosol and environmental parameters, our model reproduces a large range of ηα values derived from homogeneous ice nucleation parameterizations widely used in global climate models (GCMs). The differences in ηα from these parameterizations can translate into a range of anthropogenic aerosol longwave indirect forcings through cirrus clouds from 0.05 to 0.36 W m−2 with a GCM. Our study suggests that a larger ηα (0.1–0.3) is more plausible and the homogeneous nucleation parameterizations should include a realistic aerosol size distribution to accurately quantify anthropogenic aerosol indirect effects. ©2018. American Geophysical Union. All Rights Reserved."
"55613774900;24315205000;56724683700;15069732800;6701410329;","Trends and Variability of Surface Solar Radiation in Europe Based On Surface- and Satellite-Based Data Records",2018,"10.1002/2017JD027418","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041667347&doi=10.1002%2f2017JD027418&partnerID=40&md5=9b5ed290fd0274a6f5168a3b4d1a33e7","The incoming solar radiation is the essential climate variable that determines the Earth's energy cycle and climate. As long-term high-quality surface measurements of solar radiation are rare, satellite data are used to derive more information on its spatial pattern and its temporal variability. Recently, the EUMETSAT Satellite Application on Climate Monitoring (CM SAF) has published two satellite-based climate data records: Surface Solar Radiation Data Set-Heliosat, Edition 2 (SARAH-2), and Clouds and Radiation Data Set based on AVHRR (advanced very high resolution radiometer) Satellite Measurements, Edition 2 (CLARA-A2). Both data records provide estimates of surface solar radiation. In this study, these new climate data records are compared to surface measurements in Europe during the period 1983–2015. SARAH-2 and CLARA-A2 show a high accuracy compared to ground-based observations (mean absolute deviations of 6.9 and 7.3 W/m2, respectively) highlighting a good agreement considering the temporal behavior and the spatial distribution. The results show an overall brightening period since the 1980s onward (comprised between 1.9 and 2.4 W/m2/decade), with substantial decadal and spatial variability. The strongest brightening is found in eastern Europe in spring. An exception is found for northern and southern Europe, where the trends shown by the station data are not completely reproduced by satellite data, especially in summer in southern Europe. We conclude that the major part of the observed trends in surface solar radiation in Europe is caused by changes in clouds and that remaining differences between the satellite- and the station-based data might be connected to changes in the direct aerosol effect and in snow cover. ©2018. American Geophysical Union. All Rights Reserved."
"36921601500;55973367800;7402333662;","Satellite Observations of Stratospheric Gravity Waves Associated With the Intensification of Tropical Cyclones",2018,"10.1002/2017GL076123","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041851570&doi=10.1002%2f2017GL076123&partnerID=40&md5=6b625cfe676fa48dd39e9922a8bc5eb9","Forecasting the intensity of tropical cyclones is a challenging problem. Rapid intensification is often preceded by the formation of “hot towers” near the eyewall. Driven by strong release of latent heat, hot towers are high-reaching tropical cumulonimbus clouds that penetrate the tropopause. Hot towers are a potentially important source of stratospheric gravity waves. Using 13.5 years (2002–2016) of Atmospheric Infrared Sounder observations of stratospheric gravity waves and tropical cyclone data from the International Best Track Archive for Climate Stewardship, we found empirical evidence that stratospheric gravity wave activity is associated with the intensification of tropical cyclones. The Atmospheric Infrared Sounder and International Best Track Archive for Climate Stewardship data showed that strong gravity wave events occurred about twice as often for tropical cyclone intensification compared to storm weakening. Observations of stratospheric gravity waves, which are not affected by obscuring tropospheric clouds, may become an important future indicator of storm intensification. ©2018. American Geophysical Union. All Rights Reserved."
"52863356900;55688930000;55544607500;15755995900;7006705919;7005809959;","Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model",2018,"10.1002/2017JD027244","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041313690&doi=10.1002%2f2017JD027244&partnerID=40&md5=9f942b61b3bc5f90ee486fc28cc53490","The relationship between forcing and emission is investigated for black carbon (BC) and primary organic carbon (OC) emitted from North America and Asia. Direct and indirect radiative forcing (DRF and IRF) of BC and OC are simulated with CAM5.1. Two diagnostics are introduced to aid policy-relevant discussions: linearity and emission-normalized forcing. DRF is linearly related to emission for both BC and OC from two regions, and the linear relationship is similar, within 15%. IRF is linear in emissions when emissions are lower and regions are far from sources (North American BC and OC). Indirect radiative forcing is sublinear for strong sources and near-source regions (Asian OC). Emission-normalized IRF in North America is two to four times higher than that in Asia. The difference among regions and species is primarily caused by particle density as high density of BC results in fewer emitted particles and by the processes for accumulation mode particles to become cloud condensation nuclei and then to activate into cloud droplet. Lower emission-normalized IRF in more polluted regions means that reductions of OC in these regions would be relatively climate-neutral rather than causing significant warming via IRF reduction. An optimal aggregation area (30° × 30°) is identified for analysis of the forcing-to-emission relationship. For IRF, only 15–40% of the Earth's surface is significantly affected by an emission region, but forcing in these regions comprises most of the global impact. Emission-normalized forcing can be used to estimate forcing changes due to emission reductions, as long as causes of nonlinearity are identified and considered. ©2018. American Geophysical Union. All Rights Reserved."
"57200753788;15822963700;57196115458;","The Effects of Deep Convection on Regional Temperature Structure in the Tropical Upper Troposphere and Lower Stratosphere",2018,"10.1002/2017JD027120","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042386094&doi=10.1002%2f2017JD027120&partnerID=40&md5=837fecdcdfc8233750a522c5a2cc4c2e","Understanding the impact of deep convection on the thermodynamic structure of the tropical upper troposphere and lower stratosphere (UTLS) is vital because convection and temperatures play an important role in regulating stratospheric water vapor through direct convective injection and in enhancing the presence of thin cirrus clouds, both of which play a significant role in the climate. This study quantifies the UTLS vertical temperature structure changes near deep convection over the Pacific Warm Pool and the Tropical Atlantic Continental and Oceanic region. The deep convection observed from the Tropical Rainfall Measuring Mission satellite are collocated with high vertical resolution temperature profiles from the COSMIC GPS Radio Occultation satellites along with ERA-Interim reanalysis from 2007 to 2011. COSMIC and ERA-Interim observe warm temperature anomalies (0.2 to 0.8 K) within 10–14 km, then transitioning to a layer of cool anomalies (−0.4 to −1.5 K) within 14–17 km. Above the cold-point tropopause, warm anomalies (<1 K) are observed for oceanic convection, whereas cool anomalies are displayed for land convection within 17–20 km. The amplitude of temperature anomalies increases for deeper convection, marked by higher 20 dBZ radar echo top heights or colder infrared cloud top temperatures. COSMIC also observes enhanced UTLS diurnal temperature variations of about 0.2–0.3 K in both regions near deep convection. ERA-Interim shows generally good agreement with COSMIC on the UTLS temperature anomalies near deep convection but displays larger differences above the tropopause, especially near land convection. ©2018. American Geophysical Union. All Rights Reserved."
"55388662200;36238075700;","Association of direct normal irradiance with El Niño Southern Oscillation and its consequence on concentrated solar power production in the US Southwest",2018,"10.1016/j.apenergy.2017.12.102","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040037553&doi=10.1016%2fj.apenergy.2017.12.102&partnerID=40&md5=3b95d72ddc8cb48abc373dcafded9494","The US Southwest is among the most suitable regions for the employment of concentrated solar power (CSP). The high fluctuations of direct normal irradiance (DNI) lead to significant variabilities in CSP plants power output. El Niño Southern Oscillation (ENSO) has been proven as a large-scale climate phenomenon that influences the climatic behaviors and meteorological variables in the US southwest. In this study, the impacts of ENSO on DNI and CSP plants electricity production are investigated in four US southwest States of Arizona, California, Nevada and New Mexico, using 50 years (1961–2010) collected DNI data. The results demonstrate that responses of DNI to ENSO are both location and seasonal dependent due to the specific climate and DNI features of each site. Furthermore, the conducted analysis shows that each ENSO type and intensity has distinct impacts on DNI. The changes in the variability, distribution and magnitude of DNI during ENSO events can be due to changes in the atmospheric contents, cloud amounts and precipitation level caused by ENSO events. These changes lead to magnitude and continuity variations of CSP plants power output. Such variations necessitate optimizing the thermal energy storage utilization schedule and back-up energy source requirements for CSP power plants. © 2017 Elsevier Ltd"
"55831437900;57206503877;","Energy transport, polar amplification, and ITCZ shifts in the GeoMIP G1 ensemble",2018,"10.5194/acp-18-2287-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042146117&doi=10.5194%2facp-18-2287-2018&partnerID=40&md5=8a295c057da9b6de77fc5bdc95d59780","The polar amplification of warming and the ability of the Intertropical Convergence Zone (ITCZ) to shift to the north or south are two very important problems in climate science. Examining these behaviors in global climate models (GCMs) running solar geoengineering experiments is helpful not only for predicting the effects of solar geoengineering but also for understanding how these processes work under increased carbon dioxide (CO2). Both polar amplification and ITCZ shifts are closely related to the meridional transport of moist static energy (MSE) by the atmosphere. This study examines changes in MSE transport in 10 fully coupled GCMs in experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP), in which the solar constant is reduced to compensate for the radiative forcing from abruptly quadrupled CO2 concentrations. In G1, poleward MSE transport decreases relative to preindustrial conditions in all models, in contrast to the Coupled Model Intercomparison Project phase 5 (CMIP5) abrupt4xCO2 experiment, in which poleward MSE transport increases. We show that since poleward energy transport decreases rather than increases, and local feedbacks cannot change the sign of an initial temperature change, the residual polar amplification in the G1 experiment must be due to the net positive forcing in the polar regions and net negative forcing in the tropics, which arise from the different spatial patterns of the simultaneously imposed solar and CO2 forcings. However, the reduction in poleward energy transport likely plays a role in limiting the polar warming in G1. An attribution study with a moist energy balance model shows that cloud feedbacks are the largest source of uncertainty regarding changes in poleward energy transport in midlatitudes in G1, as well as for changes in cross-equatorial energy transport, which are anticorrelated with ITCZ shifts. © 2018 Author(s)."
"55937653600;57200652740;35735005100;24337553400;55494568400;23399196900;57205707345;57200649479;55495632500;15047161300;","Optical and microphysical properties of natural mineral dust and anthropogenic soil dust near dust source regions over northwestern China",2018,"10.5194/acp-18-2119-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042106757&doi=10.5194%2facp-18-2119-2018&partnerID=40&md5=ead69d4192a7f6a3e17ddbda9b658408","Mineral dust aerosols (MDs) not only influence the climate by scattering and absorbing solar radiation but also modify cloud properties and change the ecosystem. From 3 April to 16 May 2014, a ground-based mobile laboratory was deployed to measure the optical and microphysical properties of MDs near dust source regions in Wuwei, Zhangye, and Dunhuang (in chronological order) along the Hexi Corridor over northwestern China. Throughout this dust campaign, the hourly averaged (±standard deviation) aerosol scattering coefficients (σsp, 550ĝ€nm) of the particulates with aerodynamic diameters less than 2.5ĝ€μm (PM2.5) at these three sites were sequentially 101.5ĝ€±ĝ€36.8, 182.2ĝ€±ĝ€433.1, and 54.0ĝ€±ĝ€32.0ĝ€Mmĝ'1. Correspondingly, the absorption coefficients (σap, 637ĝ€nm) were 9.7ĝ€±ĝ€6.1, 6.0ĝ€±ĝ€4.6, and 2.3ĝ€±ĝ€0.9ĝ€Mmĝ'1; single-scattering albedos (I‰, 637ĝ€nm) were 0.902ĝ€±ĝ€0.025, 0.931ĝ€±ĝ€0.037, and 0.949ĝ€±ĝ€0.020; and scattering Ångström exponents (Åsp, 450-700ĝ€nm) of PM2.5 were 1.28ĝ€±ĝ€0.27, 0.77ĝ€±ĝ€0.51, and 0.52ĝ€±ĝ€0.31. During a severe dust storm in Zhangye (i.e., from 23 to 25 April), the highest values of σsp2.5 ( ĝ1/4 ĝ€5074ĝ€Mmĝ'1), backscattering coefficient (σbsp2.5, ĝ1/4 ĝ€522ĝ€Mmĝ'1), and I‰637 ( ĝ1/4 ĝ€0.993) and the lowest values of backscattering fraction (b2.5, ĝ1/4 ĝ€0.101) at 550ĝ€nm and Åsp2.5 ( ĝ1/4 ĝ€ĝ'0.046) at 450-700ĝ€nm, with peak values of aerosol number size distribution (appearing at the particle diameter range of 1-3ĝ€μm), exhibited that the atmospheric aerosols were dominated by coarse-mode dust aerosols. It is hypothesized that the relatively higher values of mass scattering efficiency during floating dust episodes in Wuwei and Zhangye are attributed to the anthropogenic soil dust produced by agricultural cultivations. © Author(s) 2018."
"55978929600;24491425800;55929058600;55991864300;55032414000;7004946565;6506336560;","Utility of photochemical traits as diagnostics of thermal tolerance amongst great barrier reef corals",2018,"10.3389/fmars.2018.00045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042071214&doi=10.3389%2ffmars.2018.00045&partnerID=40&md5=d32de10f29ff6b70d2c7095aedd84383","Light availability is considered a key factor regulating the thermal sensitivity of reef building corals, where excessive excitation of photosystem II (PSII) further exacerbates pressure on photochemical pathways already compromised by heat stress. Coral symbionts acclimate to changes in light availability (photoacclimation) by continually fine-tuning the photochemical operating efficiency of PSII. However, how this process adjusts throughout the warmest months in naturally heat-tolerant or sensitive species is unknown, and whether this influences the capacity to tolerate transient heat stress is untested. We therefore examined the PSII photophysiology of 10 coral species (with known thermal tolerances) from shallow reef environments at Heron Island (Great Barrier Reef, Australia), in spring (October-November, 2015) vs. summer (February-March, 2016). Corals were maintained in flow-through aquaria and rapid light curve (RLC) protocols using pulse amplitude modulated (PAM) fluorometry captured changes in the PSII photoacclimation strategy, characterized as the minimum saturating irradiance (Ek), and the extent of photochemical ([1-C], operating efficiency) vs. non-photochemical ([1-Q]) energy dissipation. Values of Ek across species were > 2-fold higher in all coral species in spring, consistent with a climate of higher overall light exposure (i.e., higher PAR from lower cloud cover, rainfall and wind speed) compared with summer. Summer decreases in Ek were combined with a shift toward preferential photochemical quenching in all species. All coral species were subsequently subjected to thermal stress assays. An equivalent temperature-ramping profile of 1°C increase per day and then maintenance at 32°C was applied in each season. Despite the significant seasonal photoacclimation, the species hierarchy of thermal tolerance [maximum quantum yields of PSII (Fv/Fm), monitored at dawn and dusk] did not shift between seasons, except for Pocillopora damicornis (faster declines in summer) and Stylophora pistillata (total mortality in spring). Furthermore, the strategy for dealing with light energy (i.e., preferential photochemical vs. non-photochemical quenching) was unchanged for thermally tolerant species across seasons, whereas thermally sensitive species switched between preferential [1-Q] and [1-C] from spring to summer. We discuss how such traits can potentially be used as a diagnostic of thermal tolerance under non-stressed conditions. © 2018 Nitschke, Gardner, Goyen, Fujise, Camp, Ralph and Suggett."
"57200654533;26027915100;7404226510;7102395993;13002846600;","What controls the stable isotope composition of precipitation in the mekong delta? A model-based statistical approach",2018,"10.5194/hess-22-1239-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042113295&doi=10.5194%2fhess-22-1239-2018&partnerID=40&md5=c3937bf701afb37a5e5dda14f752b04f","This study analyzes the influence of local and regional climatic factors on the stable isotopic composition of rainfall in the Vietnamese Mekong Delta (VMD) as part of the Asian monsoon region. It is based on 1.5 years of weekly rainfall samples. In the first step, the isotopic composition of the samples is analyzed by local meteoric water lines (LMWLs) and single-factor linear correlations. Additionally, the contribution of several regional and local factors is quantified by multiple linear regression (MLR) of all possible factor combinations and by relative importance analysis. This approach is novel for the interpretation of isotopic records and enables an objective quantification of the explained variance in isotopic records for individual factors. In this study, the local factors are extracted from local climate records, while the regional factors are derived from atmospheric backward trajectories of water particles. The regional factors, i.e., precipitation, temperature, relative humidity and the length of backward trajectories, are combined with equivalent local climatic parameters to explain the response variables d18O, d2H, and d-excess of precipitation at the station of measurement.
The results indicate that (i) MLR can better explain the isotopic variation in precipitation (R2ĝ€ Combining double low line ĝ€0.8) compared to single-factor linear regression (R2ĝ€ Combining double low line ĝ€0.3); (ii) the isotopic variation in precipitation is controlled dominantly by regional moisture regimes (ĝ1/4 70ĝ€%) compared to local climatic conditions (ĝ1/4 30ĝ€%); (iii) the most important climatic parameter during the rainy season is the precipitation amount along the trajectories of air mass movement; (iv) the influence of local precipitation amount and temperature is not significant during the rainy season, unlike the regional precipitation amount effect; (v) secondary fractionation processes (e.g., sub-cloud evaporation) can be identified through the d-excess and take place mainly in the dry season, either locally for d18O and d2H, or along the air mass trajectories for d-excess. The analysis shows that regional and local factors vary in importance over the seasons and that the source regions and transport pathways, and particularly the climatic conditions along the pathways, have a large influence on the isotopic composition of rainfall. Although the general results have been reported qualitatively in previous studies (proving the validity of the approach), the proposed method provides quantitative estimates of the controlling factors, both for the whole data set and for distinct seasons. Therefore, it is argued that the approach constitutes an advancement in the statistical analysis of isotopic records in rainfall that can supplement or precede more complex studies utilizing atmospheric models. Due to its relative simplicity, the method can be easily transferred to other regions, or extended with other factors.
The results illustrate that the interpretation of the isotopic composition of precipitation as a recorder of local climatic conditions, as for example performed for paleorecords of water isotopes, may not be adequate in the southern part of the Indochinese Peninsula, and likely neither in other regions affected by monsoon processes. However, the presented approach could open a pathway towards better and seasonally differentiated reconstruction of paleoclimates based on isotopic records. © Author(s) 2018. This work is distributed under."
"7202198678;6701581258;","Accuracy and precision of polar lower stratospheric temperatures from reanalyses evaluated from A-Train CALIOP and MLS, COSMIC GPS RO, and the equilibrium thermodynamics of supercooled ternary solutions and ice clouds",2018,"10.5194/acp-18-1945-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041849087&doi=10.5194%2facp-18-1945-2018&partnerID=40&md5=94a6d20e261763abdc36f109285ae3c2","We investigate the accuracy and precision of polar lower stratospheric temperatures (100-10 hPa during 2008-2013) reported in several contemporary reanalysis datasets comprising two versions of the Modern-Era Retrospective analysis for Research and Applications (MERRA and MERRA-2), the Japanese 55-year Reanalysis (JRA-55), the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-I), and the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (NCEP-CFSR). We also include the Goddard Earth Observing System model version 5.9.1 near-real-time analysis (GEOS-5.9.1). Comparisons of these datasets are made with respect to retrieved temperatures from the Aura Microwave Limb Sounder (MLS), Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Global Positioning System (GPS) radio occultation (RO) temperatures, and independent absolute temperature references defined by the equilibrium thermodynamics of supercooled ternary solutions (STSs) and ice clouds. Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations of polar stratospheric clouds are used to determine the cloud particle types within the Aura MLS geometric field of view. The thermodynamic calculations for STS and the ice frost point use the colocated MLS gas-phase measurements of HNO3 and H2O. The estimated bias and precision for the STS temperature reference, over the 68 to 21 hPa pressure range, are 0.6-1.5 and 0.3-0.6 K, respectively; for the ice temperature reference, they are 0.4 and 0.3 K, respectively. These uncertainties are smaller than those estimated for the retrieved MLS temperatures and also comparable to GPS RO uncertainties (bias<0.2 K, precision >0.7 K) in the same pressure range. We examine a case study of the time-varying temperature structure associated with layered ice clouds formed by orographic gravity waves forced by flow over the Palmer Peninsula and compare how the wave amplitudes are reproduced by each reanalysis dataset. We find that the spatial and temporal distribution of temperatures below the ice frost point, and hence the potential to form ice polar stratospheric clouds (PSCs) in model studies driven by the reanalyses, varies significantly because of the underlying differences in the representation of mountain wave activity. High-accuracy COSMIC temperatures are used as a common reference to intercompare the reanalysis temperatures. Over the 68-21 hPa pressure range, the biases of the reanalyses with respect to COSMIC temperatures for both polar regions fall within the narrow range of -0.6K to C0.5 K. GEOS-5.9.1, MERRA, MERRA-2, and JRA-55 have predominantly cold biases, whereas ERA-I has a predominantly warm bias. NCEP-CFSR has a warm bias in the Arctic but becomes substantially colder in the Antarctic. Reanalysis temperatures are also compared with the PSC reference temperatures. Over the 68-21 hPa pressure range, the reanalysis temperature biases are in the range -1.6 to -0.3K with standard deviations 0.6K for the CALIOP STS reference, and in the range -0.9 to +0.1K with standard deviations 0.7K for the CALIOP ice reference. Comparisons of MLS temperatures with the PSC reference tem- peratures reveal vertical oscillations in the MLS temperatures and a significant low bias in MLS temperatures of up to 3 K. © Author(s) 2018."
"57189502074;7003718864;57196755283;24472698700;6603581315;","Insights into Atlantic multidecadal variability using the Last Millennium Reanalysis framework",2018,"10.5194/cp-14-157-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041894075&doi=10.5194%2fcp-14-157-2018&partnerID=40&md5=294fcf72dc3839fbdcbef218bfab16c6","The Last Millennium Reanalysis (LMR) employs a data assimilation approach to reconstruct climate fields from annually resolved proxy data over years 0-2000ĝ-CE. We use the LMR to examine Atlantic multidecadal variability (AMV) over the last 2 millennia and find several robust thermodynamic features associated with a positive Atlantic Multidecadal Oscillation (AMO) index that reveal a dynamically consistent pattern of variability: The Atlantic and most continents warm; sea ice thins over the Arctic and retreats over the Greenland, Iceland, and Norwegian seas; and equatorial precipitation shifts northward. The latter is consistent with anomalous southward energy transport mediated by the atmosphere. Net downward shortwave radiation increases at both the top of the atmosphere and the surface, indicating a decrease in planetary albedo, likely due to a decrease in low clouds. Heat is absorbed by the climate system and the oceans warm. Wavelet analysis of the AMO time series shows a reddening of the frequency spectrum on the 50-to 100-year timescale, but no evidence of a distinct multidecadal or centennial spectral peak. This latter result is insensitive to both the choice of prior model and the calibration dataset used in the data assimilation algorithm, suggesting that the lack of a distinct multidecadal spectral peak is a robust result. © 2018 Author."
"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."
"56803816200;35768178600;6603910469;57203474131;","Assessment of the Weather Research and Forecasting (WRF) model for simulation of extreme rainfall events in the upper Ganga Basin",2018,"10.5194/hess-22-1095-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041795551&doi=10.5194%2fhess-22-1095-2018&partnerID=40&md5=71cd8e8b9162aa6878a82ebc86ea68ca","Reliable estimates of extreme rainfall events are necessary for an accurate prediction of floods. Most of the global rainfall products are available at a coarse resolution, rendering them less desirable for extreme rainfall analysis. Therefore, regional mesoscale models such as the advanced research version of the Weather Research and Forecasting (WRF) model are often used to provide rainfall estimates at fine grid spacing. Modelling heavy rainfall events is an enduring challenge, as such events depend on multi-scale interactions, and the model configurations such as grid spacing, physical parameterization and initialization. With this background, the WRF model is implemented in this study to investigate the impact of different processes on extreme rainfall simulation, by considering a representative event that occurred during 15-18 June 2013 over the Ganga Basin in India, which is located at the foothills of the Himalayas. This event is simulated with ensembles involving four different microphysics (MP), two cumulus (CU) parameterizations, two planetary boundary layers (PBLs) and two land surface physics options, as well as different resolutions (grid spacing) within the WRF model. The simulated rainfall is evaluated against the observations from 18 rain gauges and the Tropical Rainfall Measuring Mission Multi-Satellite Precipitation Analysis (TMPA) 3B42RT version 7 data. From the analysis, it should be noted that the choice of MP scheme influences the spatial pattern of rainfall, while the choice of PBL and CU parameterizations influences the magnitude of rainfall in the model simulations. Further, the WRF run with Goddard MP, Mellor-Yamada-Janjic PBL and Betts-Miller-Janjic CU scheme is found to perform best
in simulating this heavy rain event. The selected configuration is evaluated for several heavy to extremely heavy rainfall events that occurred across different months of the monsoon season in the region. The model performance improved through incorporation of detailed land surface processes involving prognostic soil moisture evolution in Noah scheme compared to the simple Slab model. To analyse the effect of model grid spacing, two sets of downscaling ratios - (i) 1:3, global to regional (G2R) scale and (ii) 1:9, global to convection-permitting scale (G2C) - are employed. Results indicate that a higher downscaling ratio (G2C) causes higher variability and consequently large errors in the simulations. Therefore, G2R is adopted as a suitable choice for simulating heavy rainfall event in the present case study. Further, the WRF-simulated rainfall is found to exhibit less bias when compared with the NCEP FiNaL (FNL) reanalysis data. © Author(s) 2018."
"35731251200;43561092300;55683113200;55481489700;57200536402;57200535228;7005773698;","The cloud nucleating properties and mixing state of marine aerosols sampled along the Southern California coast",2018,"10.3390/atmos9020052","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041545072&doi=10.3390%2fatmos9020052&partnerID=40&md5=264875a150c916ac0233459b145628a2","Marine aerosols are a globally significant contributor to aerosol-cloud-climate interactions; however, the impact that different sources of pollution and natural emissions from the ocean have on the water uptake properties of marine aerosols remains largely underexplored. Here we present measurements of the cloud condensation nuclei (CCN) activation of marine aerosols taken in a coastal, marine environment impacted by sea spray aerosol and different sources of pollution. The hygroscopicity parameter, κ, was found to range from < 0.1 up to 1.4 with a campaign-average value of 0.22 ± 0.12. Smaller particles were less hygroscopic than larger ones, and κ varied diurnally and temporally as a function of air mass transport conditions. Measurements made using aerosol time-of-flight mass spectrometry (ATOFMS) revealed that heterogeneous reactions, sulfates, and temporal differences in the observed particle types had the largest impacts on the observed κ values. The aerosol mixing-state was also found to affect κ. Temporal differences between freshly-emitted soot and aged soot internally mixed with sulfates, likely emitted from ships, had the largest impact on diurnal variations in κ. Our results further demonstrate the significant impact that pollution and the aerosol mixing-state have on aerosol-cloud interactions in the marine boundary layer. © 2018 by the authors."
"57196699811;24177361900;57200564815;7003968166;","Lagrangian process attribution of isotopic variations in near-surface water vapour in a 30-year regional climate simulation over Europe",2018,"10.5194/acp-18-1653-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041641381&doi=10.5194%2facp-18-1653-2018&partnerID=40&md5=db1e653a6794c70b16657f6561b63ac9","Stable water isotopes are naturally available tracers of moisture in the atmosphere. Due to isotopic fractionation, they record information about condensation and evaporation processes during the transport of air parcels, and therefore present a valuable means for studying the global water cycle. However, the meteorological processes driving isotopic variations are complex and not very well understood so far, in particular on short (hourly to daily) timescales. This study presents a Lagrangian method for attributing the isotopic composition of air parcels to meteorological processes, which provides new insight into the isotopic history of air parcels. It is based on the temporal evolution of the isotope ratios, the humidity, the temperature, and the location of the air parcels. Here these values are extracted along 7-day backward trajectories started every 6 hours from near the surface in a 30-year regional climate simulation over Europe with the isotope-enabled version of the model of the Consortium for Small-Scale Modelling (COSMOiso). The COSMOiso simulation has a horizontal resolution of 0.25° and is driven at the lateral boundaries by a T106 global climate simulation with the isotope-enabled version of the European Centre Hamburg model (ECHAMwiso). Both simulations are validated against measurements from the Global Network of Isotopes in Precipitation (GNIP), which shows that nesting COSMOiso within ECHAMwiso improves the representation of 2H and deuterium excess in monthly accumulated precipitation. The method considers all isotopic changes that occur inside the COSMOiso model domain, which, on average, correspond to more than half of the mean and variability in both 2H and deuterium excess at the air parcels' arrival points. Along every trajectory, the variations in the isotope values are quantitatively decomposed into eight process categories (evaporation from the ocean, evapotranspiration from land, mixing with moister air, mixing with drier air, liquid cloud formation, mixed phase cloud formation, ice cloud formation, and no process). The results show that for air parcels arriving over the ocean, evaporation from the ocean is the primary factor controlling 2H and deuterium excess. Over land, evapotranspiration from land and mixing with moister air are similarly important. Liquid and mixed phase cloud formation contribute to the variability of 2H and deuterium excess, especially over continental Europe. In summary, the presented method helps to better understand the linkage between the meteorological history of air parcels and their isotopic composition, and may support the interpretation of stable water isotope measurements in future."
"55623265200;18635208300;7004479957;","Variability in modeled cloud feedback tied to differences in the climatological spatial pattern of clouds",2018,"10.1007/s00382-017-3673-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017174904&doi=10.1007%2fs00382-017-3673-2&partnerID=40&md5=7e5f85b7934fb5ac28f20c67a30ad195","Despite the increasing sophistication of climate models, the amount of surface warming expected from a doubling of atmospheric CO2 (equilibrium climate sensitivity) remains stubbornly uncertain, in part because of differences in how models simulate the change in global albedo due to clouds (the shortwave cloud feedback). Here, model differences in the shortwave cloud feedback are found to be closely related to the spatial pattern of the cloud contribution to albedo (α) in simulations of the current climate: high-feedback models exhibit lower (higher) α in regions of warm (cool) sea-surface temperatures, and therefore predict a larger reduction in global-mean α as temperatures rise and warm regions expand. The spatial pattern of α is found to be strongly predictive (r= 0.84) of a model’s global cloud feedback, with satellite observations indicating a most-likely value of 0.58 ± 0.31 Wm- 2 K- 1 (90% confidence). This estimate is higher than the model-average cloud feedback of 0.43 Wm- 2 K- 1, with half the range of uncertainty. The observational constraint on climate sensitivity is weaker but still significant, suggesting a likely value of 3.68 ± 1.30 K (90% confidence), which also favors the upper range of model estimates. These results suggest that uncertainty in model estimates of the global cloud feedback may be substantially reduced by ensuring a realistic distribution of clouds between regions of warm and cool SSTs in simulations of the current climate. © 2017, Springer-Verlag Berlin Heidelberg."
"55894937000;7004544454;55796430300;","Coupling between marine boundary layer clouds and summer-to-summer sea surface temperature variability over the North Atlantic and Pacific",2018,"10.1007/s00382-017-3651-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016474214&doi=10.1007%2fs00382-017-3651-8&partnerID=40&md5=c71a27ee542cf107e5e85e8e817f10af","Climate modes of variability over the Atlantic and Pacific may be amplified by a positive feedback between sea-surface temperature (SST) and marine boundary layer clouds. However, it is well known that climate models poorly simulate this feedback. Does this deficiency contribute to model-to-model differences in the representation of climate modes of variability? Over both the North Atlantic and Pacific, typical summertime interannual to interdecadal SST variability exhibits horseshoe-like patterns of co-located anomalies of shortwave cloud radiative effect (CRE), low-level cloud fraction, SST, and estimated inversion strength over the subtropics and midlatitudes that are consistent with a positive cloud feedback. During winter over the midlatitudes, this feedback appears to be diminished. Models participating in the Coupled Model Intercomparison Project phase 5 that simulate a weak feedback between subtropical SST and shortwave CRE produce smaller and less realistic amplitudes of summertime SST and CRE variability over the northern oceans compared to models with a stronger feedback. The change in SST amplitude per unit change in CRE amplitude among the models and observations may be understood as the temperature response of the ocean mixed layer to a unit change in radiative flux over the course of a season. These results highlight the importance of boundary layer clouds in interannual to interdecadal atmosphere–ocean variability over the northern oceans during summer. The results also suggest that deficiencies in the simulation of these clouds in coupled climate models contribute to underestimation in their simulation of summer-to-summer SST variability. © 2017, Springer-Verlag Berlin Heidelberg."
"56230988400;6602364115;","Can We Use Single-Column Models for Understanding the Boundary Layer Cloud-Climate Feedback?",2018,"10.1002/2017MS001113","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041196991&doi=10.1002%2f2017MS001113&partnerID=40&md5=d602b85595fab0d7d00c7168f4f1c5b0","This study explores how to drive Single-Column Models (SCMs) with existing data sets of General Circulation Model (GCM) outputs, with the aim of studying the boundary layer cloud response to climate change in the marine subtropical trade wind regime. The EC-EARTH SCM is driven with the large-scale tendencies and boundary conditions as derived from two different data sets, consisting of high-frequency outputs of GCM simulations. SCM simulations are performed near Barbados Cloud Observatory in the dry season (January–April), when fair-weather cumulus is the dominant low-cloud regime. This climate regime is characterized by a near equilibrium in the free troposphere between the long-wave radiative cooling and the large-scale advection of warm air. In the SCM, this equilibrium is ensured by scaling the monthly mean dynamical tendency of temperature and humidity such that it balances that of the model physics in the free troposphere. In this setup, the high-frequency variability in the forcing is maintained, and the boundary layer physics acts freely. This technique yields representative cloud amount and structure in the SCM for the current climate. Furthermore, the cloud response to a sea surface warming of 4 K as produced by the SCM is consistent with that of the forcing GCM. © 2017. The Authors."
"7202733689;7003543851;","On the compensation between cloud feedback and cloud adjustment in climate models",2018,"10.1007/s00382-017-3682-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017449980&doi=10.1007%2fs00382-017-3682-1&partnerID=40&md5=63459187e634405dc95b95b50a9b436a","Intermodel compensation between cloud feedback and rapid cloud adjustment has important implications for the range of model-inferred climate sensitivity. Although this negative intermodel correlation exists in both realistic (e.g., coupled ocean–atmosphere models) and idealized (e.g., aqua-planet) model configurations, the compensation appears to be stronger in the latter. The cause of the compensation between feedback and adjustment, and its dependence on model configuration remain poorly understood. In this study, we examine the characteristics of the cloud feedback and adjustment in model simulations with differing complexity, and analyze the causes responsible for their compensation. We show that in all model configurations, the intermodel compensation between cloud feedback and cloud adjustment largely results from offsetting changes in marine boundary-layer clouds. The greater prevalence of these cloud types in aqua-planet models is a likely contributor to the larger correlation between feedback and adjustment in those configurations. It is also shown that differing circulation changes in the aqua-planet configuration of some models act to amplify the intermodel range and sensitivity of the cloud radiative response by about a factor of 2. © 2017, Springer-Verlag Berlin Heidelberg."
"56555458900;7408519295;","Can CFMIP2 models reproduce the leading modes of cloud vertical structure in the CALIPSO-GOCCP observations?",2018,"10.1007/s00704-017-2051-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012293312&doi=10.1007%2fs00704-017-2051-7&partnerID=40&md5=fc6a2e64c7f034be0f340a15295d33ba","Using principal component (PC) analysis, three leading modes of cloud vertical structure (CVS) are revealed by the GCM-Oriented CALIPSO Cloud Product (GOCCP), i.e. tropical high, subtropical anticyclonic and extratropical cyclonic cloud modes (THCM, SACM and ECCM, respectively). THCM mainly reflect the contrast between tropical high clouds and clouds in middle/high latitudes. SACM is closely associated with middle-high clouds in tropical convective cores, few-cloud regimes in subtropical anticyclonic clouds and stratocumulus over subtropical eastern oceans. ECCM mainly corresponds to clouds along extratropical cyclonic regions. Models of phase 2 of Cloud Feedback Model Intercomparison Project (CFMIP2) well reproduce the THCM, but SACM and ECCM are generally poorly simulated compared to GOCCP. Standardized PCs corresponding to CVS modes are generally captured, whereas original PCs (OPCs) are consistently underestimated (overestimated) for THCM (SACM and ECCM) by CFMIP2 models. The effects of CVS modes on relative cloud radiative forcing (RSCRF/RLCRF) (RSCRF being calculated at the surface while RLCRF at the top of atmosphere) are studied in terms of principal component regression method. Results show that CFMIP2 models tend to overestimate (underestimated or simulate the opposite sign) RSCRF/RLCRF radiative effects (REs) of ECCM (THCM and SACM) in unit global mean OPC compared to observations. These RE biases may be attributed to two factors, one of which is underestimation (overestimation) of low/middle clouds (high clouds) (also known as stronger (weaker) REs in unit low/middle (high) clouds) in simulated global mean cloud profiles, the other is eigenvector biases in CVS modes (especially for SACM and ECCM). It is suggested that much more attention should be paid on improvement of CVS, especially cloud parameterization associated with particular physical processes (e.g. downwelling regimes with the Hadley circulation, extratropical storm tracks and others), which may be crucial to reduce the CRF biases in current climate models. © 2017, The Author(s)."
"6506328135;34881780600;7005446873;7006432091;34772240500;","A Stochastic Framework for Modeling the Population Dynamics of Convective Clouds",2018,"10.1002/2017MS001214","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042173538&doi=10.1002%2f2017MS001214&partnerID=40&md5=253026b95a2660acced3f8889c8da9fc","A stochastic prognostic framework for modeling the population dynamics of convective clouds and representing them in climate models is proposed. The framework follows the nonequilibrium statistical mechanical approach to constructing a master equation for representing the evolution of the number of convective cells of a specific size and their associated cloud-base mass flux, given a large-scale forcing. In this framework, referred to as STOchastic framework for Modeling Population dynamics of convective clouds (STOMP), the evolution of convective cell size is predicted from three key characteristics of convective cells: (i) the probability of growth, (ii) the probability of decay, and (iii) the cloud-base mass flux. STOMP models are constructed and evaluated against CPOL radar observations at Darwin and convection permitting model (CPM) simulations. Multiple models are constructed under various assumptions regarding these three key parameters and the realisms of these models are evaluated. It is shown that in a model where convective plumes prefer to aggregate spatially and the cloud-base mass flux is a nonlinear function of convective cell area, the mass flux manifests a recharge-discharge behavior under steady forcing. Such a model also produces observed behavior of convective cell populations and CPM simulated cloud-base mass flux variability under diurnally varying forcing. In addition to its use in developing understanding of convection processes and the controls on convective cell size distributions, this modeling framework is also designed to serve as a nonequilibrium closure formulations for spectral mass flux parameterizations. © 2018. The Authors."
"57200926820;","Boundary Layer Height and Buoyancy Determine the Horizontal Scale of Convective Self-Aggregation",2018,"10.1175/JAS-D-17-0150.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042216972&doi=10.1175%2fJAS-D-17-0150.1&partnerID=40&md5=66f93d5b181de9ee3db77e5f2f7a73cc","Organized rainstorms and their associated overturning circulations can self-emerge over an ocean surface with uniform temperature in cloud-resolving simulations. This phenomenon is referred to as convective self-aggregation. Convective self-aggregation is argued to be an important building block for tropical weather systems and may help regulate tropical atmospheric humidity and thereby tropical climate stability. Here the author presents a boundary layer theory for the horizontal scale λ of 2D (x, z) convective self-aggregation by considering both the momentum and energy constraints for steady circulations. This theory suggests that λ scales with the product of the boundary layer height h and the square root of the amplitude of density variation between aggregated moist and dry regions in the boundary layer, and that this density variation mainly arises from the moisture variation due to the virtual effect of water vapor. This theory predicts the following: 1) the order of magnitude of λ is ~2000 km, 2) the aspect ratio of the boundary layer λ/h increases with surface warming, and 3) λ decreases when the virtual effect of water vapor is disabled. These predictions are confirmed using a suite of cloud-resolving simulations spanning a wide range of climates. © 2018 American Meteorological Society."
"57188921914;6602761005;11940329900;36097134700;","Parameterization Interactions in Global Aquaplanet Simulations",2018,"10.1002/2017MS000991","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041732857&doi=10.1002%2f2017MS000991&partnerID=40&md5=b536365446cd9b7b0851f7b0821b1ce5","Global climate simulations rely on parameterizations of physical processes that have scales smaller than the resolved ones. In the atmosphere, these parameterizations represent moist convection, boundary layer turbulence and convection, cloud microphysics, longwave and shortwave radiation, and the interaction with the land and ocean surface. These parameterizations can generate different climates involving a wide range of interactions among parameterizations and between the parameterizations and the resolved dynamics. To gain a simplified understanding of a subset of these interactions, we perform aquaplanet simulations with the global version of the Weather Research and Forecasting (WRF) model employing a range (in terms of properties) of moist convection and boundary layer (BL) parameterizations. Significant differences are noted in the simulated precipitation amounts, its partitioning between convective and large-scale precipitation, as well as in the radiative impacts. These differences arise from the way the subcloud physics interacts with convection, both directly and through various pathways involving the large-scale dynamics and the boundary layer, convection, and clouds. A detailed analysis of the profiles of the different tendencies (from the different physical processes) for both potential temperature and water vapor is performed. While different combinations of convection and boundary layer parameterizations can lead to different climates, a key conclusion of this study is that similar climates can be simulated with model versions that are different in terms of the partitioning of the tendencies: the vertically distributed energy and water balances in the tropics can be obtained with significantly different profiles of large-scale, convection, and cloud microphysics tendencies. © 2018. The Authors."
"57200547267;25823927100;7404438747;22635190100;7401936984;","A Diagnostic PDF Cloud Scheme to Improve Subtropical Low Clouds in NCAR Community Atmosphere Model (CAM5)",2018,"10.1002/2017MS001095","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041589314&doi=10.1002%2f2017MS001095&partnerID=40&md5=c257763f0af61ec99b3bac3ceff9ce5b","Low clouds strongly impact the radiation budget of the climate system, but their simulation in most GCMs has remained a challenge, especially over the subtropical stratocumulus region. Assuming a Gaussian distribution for the subgrid-scale total water and liquid water potential temperature, a new statistical cloud scheme is proposed and tested in NCAR Community Atmospheric Model version 5 (CAM5). The subgrid-scale variance is diagnosed from the turbulent and shallow convective processes in CAM5. The approach is able to maintain the consistency between cloud fraction and cloud condensate and thus alleviates the adjustment needed in the default relative humidity-based cloud fraction scheme. Short-term forecast simulations indicate that low cloud fraction and liquid water content, including their diurnal cycle, are improved due to a proper consideration of subgrid-scale variance over the southeastern Pacific Ocean region. Compared with the default cloud scheme, the new approach produced the mean climate reasonably well with improved shortwave cloud forcing (SWCF) due to more reasonable low cloud fraction and liquid water path over regions with predominant low clouds. Meanwhile, the SWCF bias over the tropical land regions is also alleviated. Furthermore, the simulated marine boundary layer clouds with the new approach extend further offshore and agree better with observations. The new approach is able to obtain the top of atmosphere (TOA) radiation balance with a slightly alleviated double ITCZ problem in preliminary coupled simulations. This study implies that a close coupling of cloud processes with other subgrid-scale physical processes is a promising approach to improve cloud simulations. © 2018. The Authors."
"57191838787;35204593500;13611521400;","Diagnosing relationships between mean state biases and El Niño shortwave feedback in CMIP5 models",2018,"10.1175/JCLI-D-17-0331.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041654345&doi=10.1175%2fJCLI-D-17-0331.1&partnerID=40&md5=6c248f43e4fdb20e86135637e9ddffe2","The rate of damping of tropical Pacific sea surface temperature anomalies (SSTAs) associated with El Niño events by surface shortwave heat fluxes has significant biases in current coupled climate models [phase 5 of the Coupled Model Intercomparison Project (CMIP5)]. Of 33 CMIP5 models, 16 have shortwave feedbacks that are weakly negative in comparison to observations, or even positive, resulting in a tendency of amplification of SSTAs. Two biases in the cloud response to El Niño SSTAs are identified and linked to significant mean state biases in CMIP5 models. First, cool mean SST and reduced precipitation are linked to comparatively less cloud formation in the eastern equatorial Pacific during El Niño events, driven by a weakened atmospheric ascent response. Second, a spurious reduction of cloud driven by anomalous surface relative humidity during El Niño events is present in models with more stable eastern Pacific mean atmospheric conditions and more low cloud in the mean state. Both cloud response biases contribute to a weak negative shortwave feedback or a positive shortwave feedback that amplifies El Niño SSTAs. Differences between shortwave feedback in the coupled models and the corresponding atmosphere-only models (AMIP) are also linked to mean state differences, consistent with the biases found between different coupled models. Shortwave feedback bias can still persist in AMIP, as a result of persisting weak shortwave responses to anomalous cloud and weak cloud responses to atmospheric ascent. This indicates the importance of bias in the atmosphere component to coupled model feedback and mean state biases. © 2018 American Meteorological Society."
"57200702127;57200788113;55258548500;56158925300;56158523800;56611366900;7401796996;7404829395;7005973015;7404865816;","Aerosol microphysical and radiative effects on continental cloud ensembles",2018,"10.1007/s00376-017-7091-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044255560&doi=10.1007%2fs00376-017-7091-5&partnerID=40&md5=5ae2cac82fbbdc6d7e3e793fe9778437","Aerosol–cloud–radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity (typically less than 2%) to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type. © 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."
"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."
"55578807760;6603152372;","Spatial interpolation of climate variables in Northern Germany—Influence of temporal resolution and network density",2018,"10.1016/j.ejrh.2018.02.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044443301&doi=10.1016%2fj.ejrh.2018.02.002&partnerID=40&md5=94c80023d7778e4b745d44b40fad6db2","Study region: Region in Lower Saxony (North Germany) covered by the measuring range of the weather radar device located near Hanover (approx. 50.000 m2). Study focus: This study investigates the performance of various spatial interpolation techniques for climate variables. Meteorological observations are usually recorded as site-specific point information by weather stations and estimation accuracy for unobserved locations depends generally on station density, temporal resolution, spatial variation of the variable and choice of interpolation method. This work aims to evaluate the influence of these factors on interpolation performance of different climate variables. A cross validation analysis was performed for precipitation, temperature, humidity, cloud coverage, sunshine duration, and wind speed observations. Hourly to yearly temporal resolutions and different additional information were considered. New hydrological insights: Geostatistical techniques provide a better performance for all climate variables compared to simple methods Radar data improves the estimation of rainfall with hourly temporal resolution, while topography is useful for weekly to yearly values and temperature in general. No helpful information was found for cloudiness, sunshine duration, and wind speed, while interpolation of humidity benefitted from additional temperature data. The influences of temporal resolution, spatial variability, and additional information appear to be stronger than station density effects. High spatial variability of hourly precipitation causes the highest error, followed by wind speed, cloud coverage and sunshine duration. Lowest errors occur for temperature and humidity. © 2018 The Authors"
"10140984600;","Real-time determination of Earth Radiation Budget spectral signatures for nonlinear unfiltering of results from MERBE",2018,"10.1175/JAMC-D-16-0406.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042439786&doi=10.1175%2fJAMC-D-16-0406.1&partnerID=40&md5=aa4f937f98440abdecbaae0e1b31f5d8","Among the best ways to gain more certainty in climate model prediction is to compare and constrain simulations with worldwide satellite measurements of the Earth radiation budget (ERB) short- and longwave radiant fluxes (SW and LW), which drive climate processes. Recent calls to ensure orbital ERB measurements track true climate, rather than instrument changes, led to the creation of the Moon and Earth Radiation Budget Experiment (MERBE). This independent project is recalibrating multiple existing ERB devices from different international space agencies so they adhere to common SI-traceable radiometric standards, by regularly sampling the unaltering constants of lunar reflectivity/emissivity, thus ensuring no artificial trends exist. This work details the use of MODTRAN to give an instantaneous SW and LW Earth spectrum for all scenes viewed by devices in the project, to then be used with instrument spectral responses for unfiltering radiances. In the majority of cases when data from a collocated imager are available, a dual-layer unfiltering is also performed separately on cloudy and cloud-free areas, yielding clear and overcast ERB spectral results. Additionally, use is made of improved in-flight methods to derive spectral responses from a previous American Meteorological Society study, and comparisons between Earth MERBE radiances from two identical devices operating on Terra/Aqua are shown along with results from the CERES project. These demonstrate an order of magnitude improvement in relative accuracy for edition 1 MERBE results over CERES and show that the latest CERES data are less accurate and stable than claimed. © 2018 American Meteorological Society."
"22982270700;57190227631;56228672600;19638935200;56611366900;","Role of microphysical parameterizations with droplet relative dispersion in IAP AGCM 4.1",2018,"10.1007/s00376-017-7083-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040328818&doi=10.1007%2fs00376-017-7083-5&partnerID=40&md5=959cfbd0bc5b860dca8e052848dbcd67","Previous studies have shown that accurate descriptions of the cloud droplet effective radius (Re) and the autoconversion process of cloud droplets to raindrops (Ar) can effectively improve simulated clouds and surface precipitation, and reduce the uncertainty of aerosol indirect effects in GCMs. In this paper, we implement cloud microphysical schemes including two-moment Ar and Re considering relative dispersion of the cloud droplet size distribution into version 4.1 of the Institute of Atmospheric Physics’s atmospheric GCM (IAP AGCM 4.1), which is the atmospheric component of the Chinese Academy of Sciences’ Earth System Model. Analysis of the effects of different schemes shows that the newly implemented schemes can improve both the simulated shortwave and longwave cloud radiative forcings, as compared to the standard scheme, in IAP AGCM 4.1. The new schemes also effectively enhance the large-scale precipitation, especially over low latitudes, although the influences of total precipitation are insignificant for different schemes. Further studies show that similar results can be found with the Community Atmosphere Model, version 5.1. © 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."
"6507799089;6508108081;55856856100;57199329061;57110186900;24576564600;57200435908;57200446549;57200450964;57200442805;57200439884;55857915200;7004590620;7004035832;","Fire effects and ecological recovery pathways of tropical montane cloud forests along a time chronosequence",2018,"10.1111/gcb.13951","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041316615&doi=10.1111%2fgcb.13951&partnerID=40&md5=eebf4a9c1808eb8ca4d849bd44b7854a","Tropical montane cloud forests (TMCFs) harbour high levels of biodiversity and large carbon stocks. Their location at high elevations make them especially sensitive to climate change, because a warming climate is enhancing upslope species migration, but human disturbance (especially fire) may in many cases be pushing the treeline downslope. TMCFs are increasingly being affected by fire, and the long-term effects of fire are still unknown. Here, we present a 28-year chronosequence to assess the effects of fire and recovery pathways of burned TMCFs, with a detailed analysis of carbon stocks, forest structure and diversity. We assessed rates of change of carbon (C) stock pools, forest structure and tree-size distribution pathways and tested several hypotheses regarding metabolic scaling theory (MST), C recovery and biodiversity. We found four different C stock recovery pathways depending on the selected C pool and time since last fire, with a recovery of total C stocks but not of aboveground C stocks. In terms of forest structure, there was an increase in the number of small stems in the burned forests up to 5–9 years after fire because of regeneration patterns, but no differences on larger trees between burned and unburned plots in the long term. In support of MST, after fire, forest structure appears to approximate steady-state size distribution in less than 30 years. However, our results also provide new evidence that the species recovery of TMCF after fire is idiosyncratic and follows multiple pathways. While fire increased species richness, it also enhanced species dissimilarity with geographical distance. This is the first study to report a long-term chronosequence of recovery pathways to fire suggesting faster recovery rates than previously reported, but at the expense of biodiversity and aboveground C stocks. © 2017 John Wiley & Sons Ltd"
"56256597400;7005908295;","Autocorrelation structure of convective rainfall in semiarid-arid climate derived from high-resolution X-Band radar estimates",2018,"10.1016/j.atmosres.2017.09.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033502501&doi=10.1016%2fj.atmosres.2017.09.020&partnerID=40&md5=9ee5f37605111c54019b926db984a336","Small scale rainfall variability is a key factor driving runoff response in fast responding systems, such as mountainous, urban and arid catchments. In this paper, the spatial–temporal autocorrelation structure of convective rainfall is derived with extremely high resolutions (60 m, 1 min) using estimates from an X-Band weather radar recently installed in a semiarid-arid area. The 2-dimensional spatial autocorrelation of convective rainfall fields and the temporal autocorrelation of point-wise and distributed rainfall fields are examined. The autocorrelation structures are characterized by spatial anisotropy, correlation distances ~ 1.5–2.8 km and rarely exceeding 5 km, and time-correlation distances ~ 1.8–6.4 min and rarely exceeding 10 min. The observed spatial variability is expected to negatively affect estimates from rain gauges and microwave links rather than satellite and C-/S-Band radars; conversely, the temporal variability is expected to negatively affect remote sensing estimates rather than rain gauges. The presented results provide quantitative information for stochastic weather generators, cloud-resolving models, dryland hydrologic and agricultural models, and multi-sensor merging techniques. © 2017 Elsevier B.V."
"13407895800;57191339022;36543517200;8623928000;6602675795;","High-resolution grids of hourly meteorological variables for Germany",2018,"10.1007/s00704-016-2003-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007453854&doi=10.1007%2fs00704-016-2003-7&partnerID=40&md5=2ee9f3bcd51d8698c0005cc725f53146","We present a 1-km2 gridded German dataset of hourly surface climate variables covering the period 1995 to 2012. The dataset comprises 12 variables including temperature, dew point, cloud cover, wind speed and direction, global and direct shortwave radiation, down- and up-welling longwave radiation, sea level pressure, relative humidity and vapour pressure. This dataset was constructed statistically from station data, satellite observations and model data. It is outstanding in terms of spatial and temporal resolution and in the number of climate variables. For each variable, we employed the most suitable gridding method and combined the best of several information sources, including station records, satellite-derived data and data from a regional climate model. A module to estimate urban heat island intensity was integrated for air and dew point temperature. Owing to the low density of available synop stations, the gridded dataset does not capture all variations that may occur at a resolution of 1 km2. This applies to areas of complex terrain (all the variables), and in particular to wind speed and the radiation parameters. To achieve maximum precision, we used all observational information when it was available. This, however, leads to inhomogeneities in station network density and affects the long-term consistency of the dataset. A first climate analysis for Germany was conducted. The Rhine River Valley, for example, exhibited more than 100 summer days in 2003, whereas in 1996, the number was low everywhere in Germany. The dataset is useful for applications in various climate-related studies, hazard management and for solar or wind energy applications and it is available via doi:10.5676/DWD_CDC/TRY_Basis_v001. © 2016, The Author(s)."
"56494097100;16933919600;57191610692;56448223600;57195994160;8609037700;","Climatic diagnostics associated with anomalous lightning incidence during the summer 2012/2013 in Southeast Brazil",2018,"10.1002/joc.5227","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041436332&doi=10.1002%2fjoc.5227&partnerID=40&md5=263718934e82746140c9ae1cd880529b","The State of São Paulo in Southeast Brazil experienced during the 2012/2013 summer one of the most severe electrical storm events in recent years, causing various impacts to society, e.g. fires and fatalities. Thus, the objective of this work is to understand which mechanisms and climatic variability modes are associated with the lightning incidence during this summer in this region. The study includes a statistical-temporal assessment of cloud-to-ground (CG) lightning occurrence comprising the 16 years period from 1999 to 2014. The results showed that, for this period of analysis, the lightning incidence was associated with climatic patterns connecting the tropical and extratropical region, through a wave train, from the Indian Ocean to South America, favouring the formation and development of convective storms over Southeast Brazil. © 2017 Royal Meteorological Society"
"7004977068;55270499000;7003877518;16031279100;","A new NDVI measure that overcomes data sparsity in cloud-covered regions predicts annual variation in ground-based estimates of high arctic plant productivity",2018,"10.1088/1748-9326/aa9f75","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048285352&doi=10.1088%2f1748-9326%2faa9f75&partnerID=40&md5=7da0acca4a7fb564c4a5eb5511daf172","Efforts to estimate plant productivity using satellite data can be frustrated by the presence of cloud cover. We developed a new method to overcome this problem, focussing on the high-arctic archipelago of Svalbard where extensive cloud cover during the growing season can prevent plant productivity from being estimated over large areas. We used a field-based time-series (2000-2009) of live aboveground vascular plant biomass data and a recently processed cloud-free MODIS-Normalised Difference Vegetation Index (NDVI) data set (2000-2014) to estimate, on a pixel-by-pixel basis, the onset of plant growth. We then summed NDVI values from onset of spring to the average time of peak NDVI to give an estimate of annual plant productivity. This remotely sensed productivity measure was then compared, at two different spatial scales, with the peak plant biomass field data. At both the local scale, surrounding the field data site, and the larger regional scale, our NDVI measure was found to predict plant biomass (adjusted R 2 = 0.51 and 0.44, respectively). The commonly used 'maximum NDVI' plant productivity index showed no relationship with plant biomass, likely due to some years having very few cloud-free images available during the peak plant growing season. Thus, we propose this new summed NDVI from onset of spring to time of peak NDVI as a proxy of large-scale plant productivity for regions such as the Arctic where climatic conditions restrict the availability of cloud-free images. © 2018 The Author(s). Published by IOP Publishing Ltd."
"55714098700;7601345593;","Assessing population movement impacts on urban heat island of Beijing during the Chinese New Year holiday: effects of meteorological conditions",2018,"10.1007/s00704-017-2043-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010782409&doi=10.1007%2fs00704-017-2043-7&partnerID=40&md5=2d369d60c60cdedb4feddebe593e89f8","Chinese New Year (CNY), or Spring Festival, is the most important of all festivals in China. We use daily observations to show that Beijing’s urban heat island (UHI) effects largely depend on precipitation, cloud cover, and water vapor but are insensitive to wind speed, during the CNY holiday season. Non-precipitating, clear, and low humidity conditions favor strong UHI effects. The CNY holiday, with some 3 billion journeys made, provides a living laboratory to explore the role of population movements in the UHI phenomenon. Averaged over the period 2004–2013, with the Olympic year of 2008 excluded, Beijing’s UHI effects during the CNY week decline by 0.48 °C relative to the background period (4 weeks including 2 to 3 weeks before, and 2 to 3 weeks after, the CNY week). With combined effects of precipitation, large cloud cover, and high water vapor excluded, the UHI effects during the CNY week averaged over the study period decline by 0.76 °C relative to the background period, significant at the 99% confidence level by Student’s t test. These results indicate that the impacts of population movements can be more easily detected when excluding unfavorable meteorological conditions to the UHI. Population movements occur not only during the CNY holiday, but also during all the time across the globe. We suggest that better understanding the role of population movements will offer new insight into anthropogenic climate modifications. © 2017, Springer-Verlag Wien."
"9249239700;56618531600;57203722524;36150977900;57144839900;56130997600;7501439334;6603126554;7202899330;57200450981;","The Impacts of Bias in Cloud-Radiation-Dynamics Interactions on Central Pacific Seasonal and El Niño Simulations in Contemporary GCMs",2018,"10.1002/2017EA000304","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041349088&doi=10.1002%2f2017EA000304&partnerID=40&md5=459968a820e8225869f7dbe8cabd95f0","Most of the global climate models (GCMs) in the Coupled Model Intercomparison Project, phase 5 do not include precipitating ice (aka falling snow) in their radiation calculations. We examine the importance of the radiative effects of precipitating ice on simulated surface wind stress and sea surface temperatures (SSTs) in terms of seasonal variation and in the evolution of central Pacific El Niño (CP-El Niño) events. Using controlled simulations with the CESM1 model, we show that the exclusion of precipitating ice radiative effects generates a persistent excessive upper-level radiative cooling and an increasingly unstable atmosphere over convective regions such as the western Pacific and tropical convergence zones. The invigorated convection leads to persistent anomalous low-level outflows which weaken the easterly trade winds, reducing upper-ocean mixing and leading to a positive SST bias in the model mean state. In CP-El Niño events, this means that outflow from the modeled convection in the central Pacific reduces winds to the east, allowing unrealistic eastward propagation of warm SST anomalies following the peak in CP-El Niño activity. Including the radiative effects of precipitating ice reduces these model biases and improves the simulated life cycle of the CP-El Niño. Improved simulations of present-day tropical seasonal variations and CP-El Niño events would increase the confidence in simulating their future behavior. ©2018. The Authors."
"36805856400;57192711205;56339079100;55495632500;55684103400;56871212500;55311589500;57194161613;57192715001;","Effect of the Indo-Pacific warm pool on lower-stratospheric water vapor and comparison with the effect of ENSO",2018,"10.1175/JCLI-D-17-0575.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040914626&doi=10.1175%2fJCLI-D-17-0575.1&partnerID=40&md5=8b66eef993367ccbc4c388112c251ff5","Time-slice experiments with the Whole Atmosphere Community Climate Model, version 4 (WACCM4), and composite analysis with satellite observations are used to demonstrate that the Indo-Pacific warm pool (IPWP) can significantly affect lower-stratospheric water vapor. It is found that a warmer IPWP significantly dries the stratospheric water vapor by causing a broad cooling of the tropopause, and vice versa for a colder IPWP. Such imprints in tropopause temperature are driven by a combination of variations in the Brewer-Dobson circulation in the stratosphere and deep convection in the troposphere. Changes in deep convection associated with El Niño-Southern Oscillation (ENSO) reportedly have a small zonal mean effect on lower-stratospheric water vapor for strong zonally asymmetric effects on tropopause temperature. In contrast, IPWP events have zonally uniform imprints on tropopause temperature. This is because equatorial planetary waves forced by latent heat release from deep convection project strongly onto ENSO but weakly onto IPWP events. © 2018 American Meteorological Society."
"6603742681;7410340979;","Variations of climate, surface energy budget, and minimum snow/ice extent over Canadian Arctic landmass for 2000-16",2018,"10.1175/JCLI-D-17-0198.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040943323&doi=10.1175%2fJCLI-D-17-0198.1&partnerID=40&md5=bb898a8546a51fad8b5d310dc36d6ffe","Snow and ice over land are important hydrological resources and sensitive indicators of climate change. The Moderate Resolution Imaging Spectroradiometer (MODIS) dataset at 250-m spatial resolution generated at the Canada Centre for Remote Sensing (CCRS) is used to derive the annual minimum snow and ice (MSI) extent over the Canadian Arctic landmass over a 17-yr time span (2000-16). The smallest MSI extent (1.53 × 105 km2) was observed in 2012, the largest (2.09 × 105 km2) was observed in 2013; the average value was 1.70 × 105 km2. Several reanalyses and observational datasets are assessed to explain the derived MSI variations: the ERA-Interim reanalysis, North American Regional Reanalysis (NARR), Clouds and the Earth's Radiant Energy System (CERES) radiative fluxes, and European Space Agency's GlobSnow dataset. Comparison with the Randolph Glacier Inventory (RGI) showed two important facts: 1) the semipermanent snowpack in the Canadian Arctic that persists through the entire melting season is a significant component relative to the ice caps and glacier-covered areas (up to 36% or 5.58 × 104 km2), and 2) the MSI variations are related to variations in the local climate dynamics such as warm season average temperature, energy fluxes, and snow cover. The correlation coefficients (absolute values) can be as high as 0.77. The reanalysis-based MSI estimates agree with satellite MSI results (average bias of 2.2 × 103 km2 or 1.3% of the mean value). © 2018 American Meteorological Society."
"55668264000;","Two types of physical inconsistency to avoid with univariate quantile mapping: A case study over North America concerning relative humidity and its parent variables",2018,"10.1175/JAMC-D-17-0177.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042452023&doi=10.1175%2fJAMC-D-17-0177.1&partnerID=40&md5=d2be497deea5f1bf56c989ae2a6dc105","Univariate quantile mapping (QM), a technique often used to statistically postprocess climate simulations, may generate physical inconsistency. This issue is investigated here by classifying physical inconsistency into two types. Type I refers to the attribution of an impossible value to a single variable, and type II refers to the breaking of a fixed intervariable relationship. Here QM is applied to relative humidity (RH) and its parent variables, namely, temperature, pressure, and specific humidity. Twelve sites representing various climate types across North America are investigated. Time series from an ensemble of ten 3-hourly simulations are postprocessed, with the CFSR reanalysis used as the reference product. For type I, results indicate that direct postprocessing of RH generates supersaturation values (≥ 100%) at relatively small frequencies of occurrence. Generated supersaturation amplitudes exceed observed values in fog and clouds. Supersaturation values are generally more frequent and higher when RH is deduced from postprocessed parent variables. For type II, results show that univariate QM practically always breaks the intervariable thermodynamic relationship. Heuristic proxies are designed for comparing the initial bias with physical inconsistency of type II, and results suggest that QM generates a problem that is arguably lesser than the one it is intended to solve. When physical inconsistency is avoided by capping one humidity variable at its saturation level and deducing the other, statistical equivalence with the reference product remains much improved relative to the initial situation. A recommendation for climate services is to postprocess RH and deduce specific humidity rather than the opposite. © 2018 American Meteorological Society."
"57198593283;57206332144;6603453147;7003907406;","EPIC spectral observations of variability in Earth's global reflectance",2018,"10.3390/rs10020254","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042524333&doi=10.3390%2frs10020254&partnerID=40&md5=748979cf31dfdd250cbfc46e716fb0aa","NASA's Earth Polychromatic Imaging Camera (EPIC) onboard NOAA's Deep Space Climate Observatory (DSCOVR) satellite observes the entire sunlit Earth every 65 to 110 min from the Sun-Earth Lagrangian L1 point. This paper presents initial EPIC shortwave spectral observations of the sunlit Earth reflectance and analyses of its diurnal and seasonal variations. The results show that the reflectance depends mostly on (1) the ratio between land and ocean areas exposed to the Sun and (2) cloud spatial and temporal distributions over the sunlit side of Earth. In particular, the paper shows that (a) diurnal variations of the Earth's reflectance are determined mostly by periodic changes in the land-ocean fraction of its the sunlit side; (b) the daily reflectance displays clear seasonal variations that are significant even without including the contributions from snow and ice in the polar regions (which can enhance daily mean reflectances by up to 2 to 6% in winter and up to 1 to 4% in summer); (c) the seasonal variations of the sunlit Earth reflectance are mostly determined by the latitudinal distribution of oceanic clouds. © 2018 by the authors."
"35235984200;22134685800;53980452600;56536265500;","Mapping Monthly Air Temperature in the Tibetan Plateau from MODIS Data Based on Machine Learning Methods",2018,"10.1109/JSTARS.2017.2787191","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041667569&doi=10.1109%2fJSTARS.2017.2787191&partnerID=40&md5=36ae12b9a5b7584e6b45c6757518d361","Detailed knowledge of air temperature (Ta) is desired for various scientific applications. However, in the Tibetan Plateau (TP), the meteorologically observed Ta is limited due to the low density and uneven distribution of stations. This paper aims to develop a 1-km resolution monthly mean Ta dataset over the TP during 2001-2015 from remote sensing and auxiliary data. 11 environmental variables were extracted from Moderate Resolution Imaging Spectroradiometer (MODIS) data, Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) data and topographic index data. Ten machine learning algorithms were implemented and compared to determine the optimal model for Ta estimation in the TP. The Cubist algorithm outperformed other methods, having the highest accuracy and the lowest sensitivity to cloud contamination. To minimize the overfitting problem, a simple forward variable selection method was introduced and six variables were selected from the original 11 environmental variables. Among these six variables, nighttime land surface temperature (Ts) was the most important predictor, followed by elevation and solar radiance. The seasonal performance of the Cubist model was also assessed. The model had good accuracies in all four seasons, with the highest accuracy in winter (R2 = 0.98 and MAE = 0.63 °C) and the lowest accuracy in summer (R2 = 0.91 and MAE = 0.86 °C). Due to the gaps in MODIS data caused by cloud cover, there were 0.39% missing values in the estimated Ta. To improve the data integrity, Delaunay triangulation interpolation was applied to fill the missing Ta values. The final monthly (2001-2015) Ta dataset had an overall accuracy of RMSE = 1.00 °C and MAE = 0.73 °C. It provides valuable information for climate change assessment and other environmental studies in the TP. © 2018 IEEE."
"56608282600;55489745300;55856020300;24461023200;","Dynamically-downscaled temperature and precipitation changes over Saskatchewan using the PRECIS model",2018,"10.1007/s00382-017-3687-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018479393&doi=10.1007%2fs00382-017-3687-9&partnerID=40&md5=6ff5be371b89962adb12a07e58a9f285","In this study, dynamically-downscaled temperature and precipitation changes over Saskatchewan are developed through the Providing Regional Climates for Impacts Studies (PRECIS) model. It can resolve detailed features within GCM grids such as topography, clouds, and land use in Saskatchewan. The PRECIS model is employed to carry out ensemble simulations for projections of temperature and precipitation changes over Saskatchewan. Temperature and precipitation variables at 14 weather stations for the baseline period are first extracted from each model run. Ranges of simulated temperature and precipitation variables are then obtained through combination of maximum and minimum values calculated from the five ensemble runs. The performance of PRECIS ensemble simulations can be evaluated through checking if observations of current temperature at each weather station are within the simulated range. Future climate projections are analyzed over three time slices (i.e., the 2030s, 2050s, and 2080s) to help understand the plausible changes in temperature and precipitation over Saskatchewan in response to global warming. The evaluation results show that the PRECIS ensemble simulations perform very well in terms of capturing the spatial patterns of temperature and precipitation variables. The results of future climate projections over three time slices indicate that there will be an obvious warming trend from the 2030s, to the 2050s, and the 2080s over Saskatchewan. The projected changes of mean temperature over the whole Saskatchewan area is [0, 2] °C in the 2030s at 10th percentile, [2, 5.5] °C in the 2050s at 50th percentile, and [3, 10] °C in the 2090s at 90th percentile. There are no significant changes in the spatial patterns of the projected total precipitation from the 2030s to the end of this century. The minimum change of the projected total precipitation over the whole Province of Saskatchewan is most likely to be −1.3% in the 2030s, and −0.2% in the 2050s, while the minimum value would be −2.1% to the end of this century at 50th percentile. © 2017, Springer-Verlag Berlin Heidelberg."
"8870038800;56183119100;6602845217;","May common model biases reduce CMIP5’s ability to simulate the recent Pacific La Niña-like cooling?",2018,"10.1007/s00382-017-3688-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017648331&doi=10.1007%2fs00382-017-3688-8&partnerID=40&md5=b62db100b3de156e90871687c642d4b5","Over the recent three decades sea surface temperate (SST) in the eastern equatorial Pacific has decreased, which helps reduce the rate of global warming. However, most CMIP5 model simulations with historical radiative forcing do not reproduce this Pacific La Niña-like cooling. Based on the assumption of “perfect” models, previous studies have suggested that errors in simulated internal climate variations and/or external radiative forcing may cause the discrepancy between the multi-model simulations and the observation. But the exact causes remain unclear. Recent studies have suggested that observed SST warming in the other two ocean basins in past decades and the thermostat mechanism in the Pacific in response to increased radiative forcing may also play an important role in driving this La Niña-like cooling. Here, we investigate an alternative hypothesis that common biases of current state-of-the-art climate models may deteriorate the models’ ability and can also contribute to this multi-model simulations-observation discrepancy. Our results suggest that underestimated inter-basin warming contrast across the three tropical oceans, overestimated surface net heat flux and underestimated local SST-cloud negative feedback in the equatorial Pacific may favor an El Niño-like warming bias in the models. Effects of the three common model biases do not cancel one another and jointly explain ~50% of the total variance of the discrepancies between the observation and individual models’ ensemble mean simulations of the Pacific SST trend. Further efforts on reducing common model biases could help improve simulations of the externally forced climate trends and the multi-decadal climate fluctuations. © 2017, Springer-Verlag Berlin Heidelberg."
"57203685695;55667384900;36598281300;16403388800;24921885300;","The effect of varying atmospheric pressure upon habitability and biosignatures of earth-like planets",2018,"10.1089/ast.2016.1632","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042237905&doi=10.1089%2fast.2016.1632&partnerID=40&md5=61163959cd49d6b5b568a15680795678","Understanding the possible climatic conditions on rocky extrasolar planets, and thereby their potential habitability, is one of the major subjects of exoplanet research. Determining how the climate, as well as potential atmospheric biosignatures, changes under different conditions is a key aspect when studying Earth-like exoplanets. One important property is the atmospheric mass, hence pressure and its influence on the climatic conditions. Therefore, the aim of the present study is to understand the influence of atmospheric mass on climate, hence habitability, and the spectral appearance of planets with Earth-like, that is, N2-O2 dominated, atmospheres orbiting the Sun at 1 AU. This work utilizes a 1D coupled, cloud-free, climate-photochemical atmospheric column model; varies atmospheric surface pressure from 0.5 to 30 bar; and investigates temperature and key species profiles, as well as emission and brightness temperature spectra in a range between 2 and 20 μm. Increasing the surface pressure up to 4 bar leads to an increase in the surface temperature due to increased greenhouse warming. Above this point, Rayleigh scattering dominates, and the surface temperature decreases, reaching surface temperatures below 273 K (approximately at ∼34 bar surface pressure). For ozone, nitrous oxide, water, methane, and carbon dioxide, the spectral response either increases with surface temperature or pressure depending on the species. Masking effects occur, for example, for the bands of the biosignatures ozone and nitrous oxide by carbon dioxide, which could be visible in low carbon dioxide atmospheres. © Copyright 2017, Mary Ann Liebert, Inc. 2017."
"57200756888;23991212200;55519994900;51864663400;","Global Effects of Superparameterization on Hydrothermal Land-Atmosphere Coupling on Multiple Timescales",2018,"10.1002/2017MS001185","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042349499&doi=10.1002%2f2017MS001185&partnerID=40&md5=0a64da58720d918867b5c42e6b736754","Many conventional General Circulation Models (GCMs) in the Global Land-Atmosphere Coupling Experiment (GLACE) tend to produce what is now recognized as overly strong land-atmosphere (L-A) coupling. We investigate the effects of cloud Superparameterization (SP) on L-A coupling on timescales beyond diurnal where it has been recently shown to have a favorable muting effect hydrologically. Using the Community Atmosphere Model v3.5 (CAM3.5) and its Superparameterized counterpart SPCAM3.5, we conducted soil moisture interference experiments following the GLACE and Atmospheric Model Intercomparison Project (AMIP) protocols. The results show that, on weekly-to-subseasonal timescales, SP also mutes hydrologic L-A coupling. This is detectable globally, and happens through the evapotranspiration-precipitation segment. But on seasonal timescales, SP does not exhibit detectable effects on hydrologic L-A coupling. Two robust regional effects of SP on thermal L-A coupling have also been explored. Over the Arabian Peninsula, SP reduces thermal L-A coupling through a straightforward control by mean rainfall reduction. More counterintuitively, over the Southwestern US and Northern Mexico, SP enhances the thermal L-A coupling in a way that is independent of rainfall and soil moisture. This signal is associated with a systematic and previously unrecognized effect of SP that produces an amplified Bowen ratio, and is detectable in multiple SP model versions and experiment designs. In addition to amplifying the present-day Bowen ratio, SP is found to amplify the climate sensitivity of Bowen ratio as well, which likely plays a role in influencing climate change predictions at the L-A interface. © 2018. The Authors."
"7404142321;16177522400;55329994600;13402835300;57203384979;19336739100;57209270110;55318394800;35986800300;55451545500;6603153821;6602799064;7103248807;7006261583;57191440708;6506554260;8982748700;18134523600;7404029779;6603887794;57200884451;36487321700;56241295200;7003679645;24077600000;56258179800;57210240098;23011078700;16445293700;","The Met Office Global Coupled Model 3.0 and 3.1 (GC3.0 and GC3.1) Configurations",2018,"10.1002/2017MS001115","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041701776&doi=10.1002%2f2017MS001115&partnerID=40&md5=145d2ca0ed1274914b3946e5f83c81cd","The Global Coupled 3 (GC3) configuration of the Met Office Unified Model is presented. Among other applications, GC3 is the basis of the United Kingdom's submission to the Coupled Model Intercomparison Project 6 (CMIP6). This paper documents the model components that make up the configuration (although the scientific descriptions of these components are in companion papers) and details the coupling between them. The performance of GC3 is assessed in terms of mean biases and variability in long climate simulations using present-day forcing. The suitability of the configuration for predictability on shorter time scales (weather and seasonal forecasting) is also briefly discussed. The performance of GC3 is compared against GC2, the previous Met Office coupled model configuration, and against an older configuration (HadGEM2-AO) which was the submission to CMIP5. In many respects, the performance of GC3 is comparable with GC2, however, there is a notable improvement in the Southern Ocean warm sea surface temperature bias which has been reduced by 75%, and there are improvements in cloud amount and some aspects of tropical variability. Relative to HadGEM2-AO, many aspects of the present-day climate are improved in GC3 including tropospheric and stratospheric temperature structure, most aspects of tropical and extratropical variability and top-of-atmosphere and surface fluxes. A number of outstanding errors are identified including a residual asymmetric sea surface temperature bias (cool northern hemisphere, warm Southern Ocean), an overly strong global hydrological cycle and insufficient European blocking. © 2017. The Authors and Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland."
"56412340900;35303913900;55577486600;55624487819;55544317800;57190089297;57200859769;","Estimation of global vegetation productivity from Global LAnd Surface Satellite data",2018,"10.3390/rs10020327","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042535095&doi=10.3390%2frs10020327&partnerID=40&md5=cf62b8ea8c851f458d49ad7d884f61d2","Accurately estimating vegetation productivity is important in research on terrestrial ecosystems, carbon cycles and climate change. Eight-day gross primary production (GPP) and annual net primary production (NPP) are contained in MODerate Resolution Imaging Spectroradiometer (MODIS) products (MOD17), which are considered the first operational datasets for monitoring global vegetation productivity. However, the cloud-contaminated MODIS leaf area index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) retrievals may introduce some considerable errors to MODIS GPP and NPP products. In this paper, global eight-day GPP and eight-day NPP were first estimated based on Global LAnd Surface Satellite (GLASS) LAI and FPAR products. Then, GPP and NPP estimates were validated by FLUXNET GPP data and BigFoot NPP data and were compared with MODIS GPP and NPP products. Compared with MODIS GPP, a time series showed that estimated GLASS GPP in our study was more temporally continuous and spatially complete with smoother trajectories. Validated with FLUXNET GPP and BigFoot NPP, we demonstrated that estimated GLASS GPP and NPP achieved higher precision for most vegetation types. © 2018 by the authors."
"56157798300;57201193822;9636267700;7801340865;56265041500;7102582535;","Study of aerosol direct and indirect effects and auto-conversion processes over the west african monsoon region using a regional climate model",2018,"10.1007/s00376-017-7077-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043752537&doi=10.1007%2fs00376-017-7077-3&partnerID=40&md5=5373a9b5eaf96e374d781611eabb729f","This study assesses the direct and indirect effects of natural and anthropogenic aerosols (e.g., black carbon and sulfate) over West and Central Africa during the West African monsoon (WAM) period (June–July–August). We investigate the impacts of aerosols on the amount of cloudiness, the influences on the precipitation efficiency of clouds, and the associated radiative forcing (direct and indirect). Our study includes the implementation of three new formulations of auto-conversion parameterization [namely, the Beheng (BH), Tripoli and Cotton (TC) and Liu and Daum (R6) schemes] in RegCM4.4.1, besides the default model’s auto-conversion scheme (Kessler). Among the new schemes, BH reduces the precipitation wet bias by more than 50% over West Africa and achieves a bias reduction of around 25% over Central Africa. Results from detailed sensitivity experiments suggest a significant path forward in terms of addressing the long-standing issue of the characteristic wet bias in RegCM. In terms of aerosol-induced radiative forcing, the impact of the various schemes is found to vary considerably (ranging from −5 to −25 W m−2). © Institute of Atmospheric Physics/Chinese Academy of Sciences, and Science Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018."
"56148991100;7102167604;8289952600;56149571100;26667030700;6603196127;36098762900;","Dependence of the Onset of the Runaway Greenhouse Effect on the Latitudinal Surface Water Distribution of Earth-Like Planets",2018,"10.1002/2017JE005383","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042376774&doi=10.1002%2f2017JE005383&partnerID=40&md5=2a5856fb90dbfdeceaf72a352f39f811","Liquid water is one of the most important materials affecting the climate and habitability of a terrestrial planet. Liquid water vaporizes entirely when planets receive insolation above a certain critical value, which is called the runaway greenhouse threshold. This threshold forms the inner most limit of the habitable zone. Here we investigate the effects of the distribution of surface water on the runaway greenhouse threshold for Earth-sized planets using a three-dimensional dynamic atmosphere model. We considered a 1 bar atmosphere whose composition is similar to the current Earth's atmosphere with a zonally uniform distribution of surface water. As previous studies have already showed, we also recognized two climate regimes: the land planet regime, which has dry low-latitude and wet high-latitude regions, and the aqua planet regime, which is globally wet. We showed that each regime is controlled by the width of the Hadley circulation, the amount of surface water, and the planetary topography. We found that the runaway greenhouse threshold varies continuously with the surface water distribution from about 130% (an aqua planet) to 180% (the extreme case of a land planet) of the present insolation at Earth's orbit. Our results indicate that the inner edge of the habitable zone is not a single sharp boundary, but a border whose location varies depending on planetary surface condition, such as the amount of surface water. Since land planets have wider habitable zones and less cloud cover, land planets would be good targets for future observations investigating planetary habitability. ©2018. American Geophysical Union. All Rights Reserved."
"57201095495;23028245500;56898396100;15051249600;55574869900;12781752400;12786455500;","Three-dimensional physical and optical characteristics of aerosols over central China from long-term CALIPSO and HYSPLIT data",2018,"10.3390/rs10020314","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042530747&doi=10.3390%2frs10020314&partnerID=40&md5=94acf69ecaa959edc88266bdac9bfeb1","Aerosols greatly influence global and regional atmospheric systems, and human life. However, a comprehensive understanding of the source regions and three-dimensional (3D) characteristics of aerosol transport over central China is yet to be achieved. Thus, we investigate the 3D macroscopic, optical, physical, and transport properties of the aerosols over central China based on the March 2007 to February 2016 data obtained from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission and the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model. Our results showed that approximately 60% of the aerosols distributed over central China originated from local areas, whereas non-locally produced aerosols constituted approximately 40%. Anthropogenic aerosols constituted the majority of the aerosol pollutants (69%) that mainly distributed less than 2.0 km above mean sea level. Natural aerosols, which are mainly composed of dust, accounted for 31% of the total aerosols, and usually existed at an altitude higher than that of anthropogenic aerosols. Aerosol particles distributed in the near surface were smaller and more spherical than those distributed above 2.0 km. Aerosol optical depth (AOD) and the particulate depolarization ratio displayed decreasing trends, with a total decrease of 0.11 and 0.016 from March 2007 to February 2016, respectively. These phenomena indicate that during the study period, the extinction properties of aerosols decreased, and the degree of sphericity in aerosol particles increased. Moreover, the annual anthropogenic and natural AOD demonstrated decreasing trends, with a total decrease of 0.07 and 0.04, respectively. This study may benefit the evaluation of the effects of the 3D properties of aerosols on regional climates. © 2018 by the authors."
"57200441251;7402270526;56647601700;23011853200;21743348300;55515304100;57190729384;56421781300;57195198884;","Ensemble of ESA/AATSR Aerosol Optical Depth Products Based on the Likelihood Estimate Method with Uncertainties",2018,"10.1109/TGRS.2017.2757910","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041371418&doi=10.1109%2fTGRS.2017.2757910&partnerID=40&md5=285bc37e152d924fa8cdade039bf2499","Within the European Space Agency Climate Change Initiative (CCI) project Aerosolcci, there are three aerosol optical depth (AOD) data sets of Advanced Along-Track Scanning Radiometer (AATSR) data. These are obtained using the ATSR-2/ATSR dual-view aerosol retrieval algorithm (ADV) by the Finnish Meteorological Institute, the Oxford-Rutherford Appleton Laboratory (RAL) Retrieval of Aerosol and Cloud (ORAC) algorithm by the University of Oxford/RAL, and the Swansea algorithm (SU) by the University of Swansea. The three AOD data sets vary widely. Each has unique characteristics: the spatial coverage of ORAC is greater, but the accuracy of ADV and SU is higher, so none is significantly better than the others, and each has shortcomings that limit the scope of its application. To address this, we propose a method for converging these three products to create a single data set with higher spatial coverage and better accuracy. The fusion algorithm consists of three parts: the first part is to remove the systematic errors; the second part is to calculate the uncertainty and fusion of data sets using the maximum likelihood estimate method; and the third part is to mask outliers with a threshold of 0.12. The ensemble AOD results show that the spatial coverage of fused data set after mask is 148%, 13%, and 181% higher than those of ADV, ORAC, and SU, respectively, and the root-mean-square error, mean absolute error, mean bias error, and relative mean bias are superior to those of the three original data sets. Thus, the accuracy and spatial coverage of the fused AOD data set masked with a threshold of 0.12 are improved compared to the original data set. Finally, we discuss the selection of mask thresholds. © 1980-2012 IEEE."
"55149793500;6603886699;57193843075;6602783179;57192804821;","Variability and trends of wet season temperature in the Sudano-Sahelian zone and relationships with precipitation",2018,"10.1007/s00382-017-3661-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017190783&doi=10.1007%2fs00382-017-3661-6&partnerID=40&md5=e57a699d7f8fd25a626de820719d15c4","The relationships between precipitation and temperature in the central Sudano-Sahelian belt are investigated by analyzing 50 years (1959–2008) of observed temperature (Tx and Tn) and rainfall variations. At daily time-scale, both Tx and Tn show a marked decrease as a response to rainfall occurrence, with a strongest departure from normal 1 day after the rainfall event (−0.5 to −2.5 °C depending on the month). The cooling is slightly larger when heavy rainfall events (>5 mm) are considered. The temperature anomalies weaken after the rainfall event, but are still significant several days later. The physical mechanisms accounting for the temperature response to precipitation are analysed. The Tx drop is accounted for by reduced incoming solar radiation associated with increased cloud cover and increased surface evaporation following surface moistening. The effect of evaporation becomes dominant a few days after the rainfall event. The reduced daytime heat storage and the subsequent sensible heat flux result in a later negative Tn anomaly. The effect of rainfall variations on temperature is significant for long-term warming trends. The rainfall decrease experienced between 1959 and 2008 accounts for a rainy season Tx increase of 0.15 to 0.3 °C, out of a total Tx increase of 1.3 to 1.5 °C. These results have strong implications on the assessment of future temperature changes. The dampening or amplifying effects of precipitation are determined by the sign of future precipitation trends. Confidence on temperature changes under global warming partly depend on the robustness of precipitation projections. © 2017, Springer-Verlag Berlin Heidelberg."
"56135196400;7401526171;6507378331;7403872687;7005052907;","A two-stage deep neural network framework for precipitation estimation from bispectral satellite information",2018,"10.1175/JHM-D-17-0077.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042644755&doi=10.1175%2fJHM-D-17-0077.1&partnerID=40&md5=19c9be33f301231ab06f0f26d9ebf9ce","Compared to ground precipitation measurements, satellite-based precipitation estimation products have the advantage of global coverage and high spatiotemporal resolutions. However, the accuracy of satellitebased precipitation products is still insufficient to serve many weather, climate, and hydrologic applications at high resolutions. In this paper, the authors develop a state-of-the-art deep learning framework for precipitation estimation using bispectral satellite information, infrared (IR), and water vapor (WV) channels. Specifically, a two-stage framework for precipitation estimation from bispectral information is designed, consisting of an initial rain/no-rain (R/NR) binary classification, followed by a second stage estimating the nonzero precipitation amount. In the first stage, the model aims to eliminate the large fraction of NR pixels and to delineate precipitation regions precisely. In the second stage, the model aims to estimate the pointwise precipitation amount accurately while preserving its heavily skewed distribution. Stacked denoising autoencoders (SDAEs), a commonly used deep learning method, are applied in both stages. Performance is evaluated along a number of common performance measures, including both R/NR and real-valued precipitation accuracy, and compared with an operational product, Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS). For R/NR binary classification, the proposed two-stage model outperforms PERSIANN-CCS by 32.56% in the critical success index (CSI). For real-valued precipitation estimation, the two-stage model is 23.40% lower in average bias, is 44.52% lower in average mean squared error, and has a 27.21% higher correlation coefficient. Hence, the two-stage deep learning framework has the potential to serve as a more accurate and more reliable satellite-based precipitation estimation product. The authors also provide some future directions for development of satellite-based precipitation estimation products in both incorporating auxiliary information and improving retrieval algorithms. © 2018 American Meteorological Society."
"56482519000;12781752400;7003668143;57209630155;36092182300;57190749385;","Impacts of insufficient observations on the monitoring of short- and long-term suspended solids variations in highly dynamic waters, and implications for an optimal observation strategy",2018,"10.3390/rs10020345","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042534037&doi=10.3390%2frs10020345&partnerID=40&md5=e7ead1ad05957a000f07b277579fc639","Coastal water regions represent some of the most fragile ecosystems, exposed to both climate change and human activities. While remote sensing provides unprecedented amounts of data for water quality monitoring on regional to global scales, the performance of satellite observations is frequently impeded by revisiting intervals and unfavorable conditions, such as cloud coverage and sun glint. Therefore, it is crucial to evaluate the impacts of varied sampling strategies (time and frequency) and insufficient observations on the monitoring of short-term and long-term tendencies of water quality parameters, such as suspended solids (SS), in highly dynamic coastal waters. Taking advantage of the first high-frequency in situ SS dataset (at 30 min sampling intervals from 2007 to 2008), collected in Deep Bay, China, this paper presents a quantitative analysis of the influences of sampling strategies on the monitoring of SS, in terms of sampling frequency and time of day. Dramatic variations of SS were observed, with standard deviation coefficients of 48.9% and 54.1%, at two fixed stations; in addition, significant uncertainties were revealed, with the average absolute percent difference of approximately 13%, related to sampling frequency and time, using nonlinear optimization and random simulation methods. For a sampling frequency of less than two observations per day, the relative error of SS was higher than 50%, and stabilized at approximately 10%, when at least four or five samplings were conducted per day. The optimal recommended sampling times for SS were at around 9:00, 12:00, 14:00, and 16:00 in Deep Bay. The ""pseudo"" MODIS SS dataset was obtained from high-frequency in situ SS measurements at 10:30 and 14:00, masked by the temporal gap distribution of MODIS coverage to avoid uncertainties propagated from atmospheric correction and SS models. Noteworthy uncertainties of daily observations from the Terra/Aqua MODIS were found, with mean relative errors of 19.2% and 17.8%, respectively, whereas at the monthly level, the mean relative error of Terra/Aqua MODIS observations was approximately 10.7% (standard deviation of 8.4%). Sensitivity analysis between MODIS coverage and SS relative errors indicated that temporal coverage (the percentage of valid MODIS observations for a month) of more than 70% is required to obtain high-precision SS measurements at a 5% error level. Furthermore, approximately 20% of relative errors were found with the coverage of 30%, which was the average coverage of satellite observations over global coastal waters. These results highlight the need for high-frequency measurements of geostationary satellites like GOCI and multi-source ocean color sensors to capture the dynamic process of coastal waters in both the short and long term. © 2018 by the authors."
"56228412200;54790508000;24072952400;6602994648;8419310500;","Monitoring pigment-driven vegetation changes in a low-Arctic tundra ecosystem using digital cameras:",2018,"10.1002/ecs2.2123","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043706996&doi=10.1002%2fecs2.2123&partnerID=40&md5=3296ef1c613228a78a6b2c95cae4f5ee","Arctic vegetation phenology is a sensitive indicator of a changing climate, and rapid assessment of vegetation status is necessary to more comprehensively understand the impacts on foliar condition and photosynthetic activity. Airborne and space-borne optical remote sensing has been successfully used to monitor vegetation phenology in Arctic ecosystems by exploiting the biophysical and biochemical changes associated with vegetation growth and senescence. However, persistent cloud cover and low sun angles in the region make the acquisition of high-quality temporal optical data within one growing season challenging. In the following study, we examine the capability of ""near-field"" remote sensing technologies, in this case digital, true-color cameras to produce surrogate in situ spectral data to characterize changes in vegetation driven by seasonal pigment dynamics. Simple linear regression was used to investigate relationships between common pigment-driven spectral indices calculated from field-based spectrometry and red, green, and blue (RGB) indices from corresponding digital photographs in three dominant vegetation communities across three major seasons at Toolik Lake, North Slope, Alaska. We chose the strongest and most consistent RGB index across all communities to represent each spectral index. Next, linear regressions were used to relate RGB indices and extracted leaf-level pigment content with a simple additive error propagation of the root mean square error. Results indicate that the green-based RGB indices had the strongest relationship with chlorophyll a and total chlorophyll, while a red-based RGB index showed moderate relationships with the chlorophyll to carotenoid ratio. The results suggest that vegetation color contributes strongly to the response of pigment-driven spectral indices and RGB data can act as a surrogate to track seasonal vegetation change associated with pigment development and degradation. Overall, we find that low-cost, easy-to-use digital cameras can monitor vegetation status and changes related to seasonal foliar condition and photosynthetic activity in three dominant, low-Arctic vegetation communities. © 2018 Beamish et al."
"13405930700;57197810517;55202341200;7201673715;7003429521;6507502618;","Building an exposed soil composite processor (SCMaP) for mapping spatial and temporal characteristics of soils with Landsat imagery (1984–2014)",2018,"10.1016/j.rse.2017.11.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035004107&doi=10.1016%2fj.rse.2017.11.004&partnerID=40&md5=b4f9dd4063f81431f6daf43c4d78a17d","Soil information with high spatial and temporal resolution is crucial to assess potential soil degradation and to achieve sustainable productivity and ultimately food security. The spatial resolution of existing soil maps can commonly be too coarse to account for local soil variations and owing to the cost and resource needs required to update information these maps lack temporal information. With improved computational processing capabilities, increased data storage and most recently, the increasing amount of freely available data (e.g. Landsat, Sentinel-2A/B), remote sensing imagery can be integrated into existing soil mapping approaches to increase temporal and spatial resolution of soil information. Satellite multi-temporal data allows for generating cloud-free, radiometrically and phenologically consistent pixel based image composites of regional scale. Such data sets are of particular use for extracting soil information in areas of intermediate climate where soils are rarely exposed. The Soil Composite Mapping Processor (SCMaP) is a new approach designed to make use of per-pixel compositing to overcome the issue of limited soil exposure. The objective of this paper is to demonstrate the automated processors ability to handle large image databases to build multispectral reflectance composite base data layers that can support large scale top soil analyses. The functionality of the SCMaP is demonstrated using Landsat imagery over Germany from 1984 to 2014 applied over 5 year periods. Three primary product levels are generated that will allow for a long term assessment and distribution of soils that include the distribution of exposed soils, a statistical information related to soil use and intensity and the generation of exposed soil reflectance image composites. The resulting composite maps provide useful value-added information on soils with the exposed soil reflectance composites showing high spatial coverage that correlate well with existing soil maps and the underlying geological structural regions. © 2017 The Authors"
"57206562504;57218315303;","Smart cities: Under-gridding the sustainability of city-districts as energy efficient-low carbon zones",2018,"10.1016/j.jclepro.2016.12.054","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009801605&doi=10.1016%2fj.jclepro.2016.12.054&partnerID=40&md5=2af1b22cfaa08505013cf3ad8e4e64b6","This paper reviews the literature on smart cities. Offering a critical synthesis of the material, it advances a Triple Helix inspired account of smart cities as future internet-based developments. In particular, as future internet-based developments covering the digital infrastructures, data management systems, renewable energies and cloud computing of a regional innovation in the Internet of Things (IoT). More specifically, as a regional innovation in the IoT that covers the morphology of urban extensions, infill and mass retrofits, which smart cities call for the development of. Focusing on the metrics of mass retrofit proposals, the paper also serves to demonstrate how the urban morphology of such regional innovations matter in the sense they tell us that being aware of the considerable energy savings and CO2 reductions, which IoTs offer cities to be smart, is not enough. Not enough, because without knowing whether the costs and benefits under-gridding the sustainability of city-districts are shared equally, it is impossible to say if the 65% energy saving and 78% reduction in CO2, attributed to the data collection, information processing and smart (micro) grids of mass retrofits is socially just. The paper suggests that in order to verify this, it is necessary for smart cities to first baseline the social-demographic structure of retrofit proposals. Then draw upon the environmental profile this evaluation generates to assess whether the regional innovation creates the wealth needed to under-grid the sustainability of city-districts. Under-grid the sustainability of city-districts as the energy efficient-low carbon zones of an inclusive growth strategy seen to be socially just. Seen to be socially just, because the costs and benefits underlying the 1.5 ha ecological footprint that surfaces from this regional innovation are equally appropriated as the proceeds of a wealth creation, which contributes to the resilience of city-districts as energy efficient-low carbon zones. As energy efficient-low carbon zones, whose inclusive growth strategy also emerges as a post-carbon economy claiming to be climate neutral. © 2016"
"56580958500;7005692975;56504563100;56146288300;8284949000;55203650800;7102300235;33568277600;27067566200;56422193500;26643081200;","Evaluation of microwave remote sensing for monitoring live fuel moisture content in the Mediterranean region",2018,"10.1016/j.rse.2017.11.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035786048&doi=10.1016%2fj.rse.2017.11.020&partnerID=40&md5=7edcc0be5bea530b292c804a54ee3e19","Live fuel moisture content (LFMC) is an important factor in fire risk management in the Mediterranean region. Drawing upon a large network of stations (the Réseau Hydrique) measuring LFMC for operational fire danger assessment in the south-eastern region of France, this study assesses the ability of several long-term passive microwave remote sensing indices to capture the LFMC temporal dynamic of various Mediterranean shrub species. Microwave remote sensing has a high potential for monitoring LFMC independently of several constraints (e.g., atmospheric and cloud contamination effects) associated with optical-infrared and thermal remote sensing observations. The following four microwave-derived indices are considered: (1) the Essential Climate Variable near-surface soil moisture (ECV_SM); (2) the root-zone soil moisture (ECV_RZSM) derived from ECV_SM; (3) the microwave polarization difference index (MPDI) computed from five microwave frequencies (C, X, Ku, K and Ka-band corresponding to 6.9, 10.7, 18.7, 23.8 and 36.5 GHz respectively); and (4) the vegetation optical depth (VOD) at C- and X-band (from the Advanced Microwave Scanning Radiometer for the Earth observing system, AMSR-E). Firstly, an evaluation of the root-zone soil moisture ECV_RZSM against a network of soil moisture measurements (SMOSMANIA in southern France) gave satisfactory results. For most of the Réseau Hydrique sites, the present study found good agreement between LFMC and individual microwave indices, including root-zone soil moisture, VOD at X-band, and MPDI at X and Ku-bands, all averaged over the 15 days preceding the in-situ LFMC measurements. VOD at X-band showed the best agreement with the in situ LFMC data (median of correlation coefficients over all in situ sites = 0.43). Further comparisons between LFMC data and several optical indices computed from the Moderate Resolution Imaging Spectrometer (MODIS) data including normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), visible atmospheric resistant index (VARI), normalized difference water index (NDWI), normalized difference infrared index 6 (NDII6), normalized difference infrared index 7 (NDII7) and global vegetation moisture index (GVMI) were made. The comparisons showed that VARI and SAVI, as optical greenness indices, outperform the microwave indices and other optical indices with median of correlation coefficients of 0.66 and 0.65, respectively. Overall, this study shows that passive microwave indices, particularly VOD, are efficient proxies for LFMC of Mediterranean shrub species and could be used along with optical indices to evaluate fire risks in the Mediterranean region. © 2017 Elsevier Inc."
"55802483300;57194159767;36661206400;8941151400;6506718302;55359575700;55800347700;7410177774;7005956394;10640192200;","Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis",2018,"10.5194/acp-18-1307-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041473586&doi=10.5194%2facp-18-1307-2018&partnerID=40&md5=8db802f89ebde2ed9875762f269ce5fc","Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed."
"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."
"56637900300;7003961970;56037285200;","Fast Adjustments of the Asian Summer Monsoon to Anthropogenic Aerosols",2018,"10.1002/2017GL076667","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040964737&doi=10.1002%2f2017GL076667&partnerID=40&md5=c0712d748944e4f1359fd4f8782a750e","Anthropogenic aerosols are a major factor contributing to human-induced climate change, particularly over the densely populated Asian monsoon region. Understanding the physical processes controlling the aerosol-induced changes in monsoon rainfall is essential for reducing the uncertainties in the future projections of the hydrological cycle. Here we use multiple coupled and atmospheric general circulation models to explore the physical mechanisms for the aerosol-driven monsoon changes on different time scales. We show that anthropogenic aerosols induce an overall reduction in monsoon rainfall and circulation, which can be largely explained by the fast adjustments over land north of 20∘N. This fast response occurs before changes in sea surface temperature (SST), largely driven by aerosol-cloud interactions. However, aerosol-induced SST feedbacks (slow response) cause substantial changes in the monsoon meridional circulation over the oceanic regions. Both the land-ocean asymmetry and meridional temperature gradient are key factors in determining the overall monsoon circulation response. ©2018. The Authors."
"56119479900;54783792600;55717074000;7410041005;","Distinct Contributions of Ice Nucleation, Large-Scale Environment, and Shallow Cumulus Detrainment to Cloud Phase Partitioning With NCAR CAM5",2018,"10.1002/2017JD027213","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040785147&doi=10.1002%2f2017JD027213&partnerID=40&md5=e4cf6fa443306897928d646e98ef971c","Mixed-phase clouds containing both liquid droplets and ice particles occur frequently at high latitudes and in the midlatitude storm track regions. Simulations of the cloud phase partitioning between liquid and ice hydrometeors in state-of-the-art global climate models are still associated with large biases. In this study, the phase partitioning in terms of liquid mass phase ratio (MPRliq, defined as the ratio of liquid mass to total condensed water mass) simulated from the NCAR Community Atmosphere Model version 5 (CAM5) is evaluated against the observational data from A-Train satellite remote sensors. Modeled MPRliq is significantly lower than observations on the global scale, especially in the Southern Hemisphere (e.g., Southern Ocean and the Antarctic). Sensitivity tests with CAM5 are conducted to investigate the distinct contributions of heterogeneous ice nucleation, shallow cumulus detrainment, and large-scale environment (e.g., winds, temperature, and water vapor) to the low MPRliq biases. Our results show that an aerosol-aware ice nucleation parameterization increases the MPRliq especially at temperatures colder than −20°C and significantly improves the model agreements with observations in the Polar regions in summer. The decrease of threshold temperature over which all detrained cloud water is liquid from 268 to 253 K enhances the MPRliq and improves the MPRliq mostly over the Southern Ocean. By constraining water vapor in CAM5 toward reanalysis, modeled low biases in many geographical regions are largely reduced through a significant decrease of cloud ice mass mixing ratio. ©2018. American Geophysical Union. All Rights Reserved."
"36553486200;57196143493;55656837900;","On the Climate Impacts of Upper Tropospheric and Lower Stratospheric Ozone",2018,"10.1002/2017JD027398","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040734249&doi=10.1002%2f2017JD027398&partnerID=40&md5=01a06ca5ca3ce2f17dedbc4203cbec88","The global warming simulations of the general circulation models (GCMs) are generally performed with different ozone prescriptions. We find that the differences in ozone distribution, especially in the upper tropospheric and lower stratospheric (UTLS) region, account for important model discrepancies shown in the ozone-only historical experiment of the Coupled Model Intercomparison Project Phase 5 (CMIP5). These discrepancies include global high cloud fraction, stratospheric temperature, and stratospheric water vapor. Through a set of experiments conducted by an atmospheric GCM with contrasting UTLS ozone prescriptions, we verify that UTLS ozone not only directly radiatively heats the UTLS region and cools the upper parts of the stratosphere but also strongly influences the high clouds due to its impact on relative humidity and static stability in the UTLS region and the stratospheric water vapor due to its impact on the tropical tropopause temperature. These consequences strongly affect the global mean effective radiative forcing of ozone, as noted in previous studies. Our findings suggest that special attention should be paid to the UTLS ozone when evaluating the climate effects of ozone depletion in the 20th century and recovery in the 21st century. UTLS ozone difference may also be important for understanding the intermodel discrepancy in the climate projections of the CMIP6 GCMs in which either prescribed or interactive ozone is used. ©2017. American Geophysical Union. All Rights Reserved."
"36494729400;8720083500;57212164759;55422350900;53981601100;56587091900;7406500188;56162305900;","Impact of East Asian Summer Monsoon on Surface Ozone Pattern in China",2018,"10.1002/2017JD027190","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040716640&doi=10.1002%2f2017JD027190&partnerID=40&md5=4069f400211600594b27a8ced39d792f","Tropospheric ozone plays a key role in regional and global atmospheric and climate systems. In East Asia, ozone can be affected both in concentration level and spatial pattern by typical monsoon climate. This paper uses three different indices to identify the strength of East Asian summer monsoon (EASM) and explores the possible impact of EASM intensity on the ozone pattern through synthetic and process analysis. The difference in ozone between three strong and three weak monsoon years was analyzed using the simulations from regional climate model RegCM4-Chem. It was found that EASM intensity can significantly influence the spatial distribution of ozone in the lower troposphere. When EASM is strong, ozone in the eastern part of China (28°N - 42° N) is reduced, but the inverse is detected in the north and south. The surface ozone difference ranges from −7 to 7 ppbv during the 3 months (June to August) of the EASM, with the most obvious difference in August. Difference of the 3 months' average ozone ranges from −3.5 to 4 ppbv. Process analysis shows that the uppermost factor controlling ozone level during summer monsoon seasons is the chemistry process. Interannual variability of EASM can impact the spatial distribution of ozone through wind in the lower troposphere, cloud cover, and downward shortwave radiation, which affect the transport and chemical formation of ozone. The phenomenon should be addressed when considering the interaction between ozone and the climate in East Asia region. ©2018. American Geophysical Union. All Rights Reserved."
"7404480911;57195574170;8953038700;8570871900;7403931916;16645127300;","Time-Dependent Cryospheric Longwave Surface Emissivity Feedback in the Community Earth System Model",2018,"10.1002/2017JD027595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040724795&doi=10.1002%2f2017JD027595&partnerID=40&md5=5784384454248d96817a44049e73c701","Frozen and unfrozen surfaces exhibit different longwave surface emissivities with different spectral characteristics, and outgoing longwave radiation and cooling rates are reduced for unfrozen scenes relative to frozen ones. Here physically realistic modeling of spectrally resolved surface emissivity throughout the coupled model components of the Community Earth System Model (CESM) is advanced, and implications for model high-latitude biases and feedbacks are evaluated. It is shown that despite a surface emissivity feedback amplitude that is, at most, a few percent of the surface albedo feedback amplitude, the inclusion of realistic, harmonized longwave, spectrally resolved emissivity information in CESM1.2.2 reduces wintertime Arctic surface temperature biases from −7.2 ± 0.9 K to −1.1 ± 1.2 K, relative to observations. The bias reduction is most pronounced in the Arctic Ocean, a region for which Coupled Model Intercomparison Project version 5 (CMIP5) models exhibit the largest mean wintertime cold bias, suggesting that persistent polar temperature biases can be lessened by including this physically based process across model components. The ice emissivity feedback of CESM1.2.2 is evaluated under a warming scenario with a kernel-based approach, and it is found that emissivity radiative kernels exhibit water vapor and cloud cover dependence, thereby varying spatially and decreasing in magnitude over the course of the scenario from secular changes in atmospheric thermodynamics and cloud patterns. Accounting for the temporally varying radiative responses can yield diagnosed feedbacks that differ in sign from those obtained from conventional climatological feedback analysis methods. ©2018. American Geophysical Union. All Rights Reserved."
"57193327928;24722339600;57193933577;16024614000;19337612500;","Drivers of Seasonal Variability in Marine Boundary Layer Aerosol Number Concentration Investigated Using a Steady State Approach",2018,"10.1002/2017JD027443","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040708764&doi=10.1002%2f2017JD027443&partnerID=40&md5=fa1a80ec77dd3b35bb629c720a7a85e3","Marine boundary layer (MBL) aerosol particles affect the climate through their interaction with MBL clouds. Although both MBL clouds and aerosol particles have pronounced seasonal cycles, the factors controlling seasonal variability of MBL aerosol particle concentration are not well constrained. In this paper an aerosol budget is constructed representing the effects of wet deposition, free-tropospheric entrainment, primary surface sources, and advection on the MBL accumulation mode aerosol number concentration (Na). These terms are then parameterized, and by assuming that on seasonal time scales Na is in steady state, the budget equation is rearranged to form a diagnostic equation for Na based on observable variables. Using data primarily collected in the subtropical northeast Pacific during the MAGIC campaign (Marine ARM (Atmospheric Radiation Measurement) GPCI (GCSS Pacific Cross-Section Intercomparison) Investigation of Clouds), estimates of both mean summer and winter Na concentrations are made using the simplified steady state model and seasonal mean observed variables. These are found to match well with the observed Na. To attribute the modeled difference between summer and winter aerosol concentrations to individual observed variables (e.g., precipitation rate and free-tropospheric aerosol number concentration), a local sensitivity analysis is combined with the seasonal difference in observed variables. This analysis shows that despite wintertime precipitation frequency being lower than summer, the higher winter precipitation rate accounted for approximately 60% of the modeled seasonal difference in Na, which emphasizes the importance of marine stratocumulus precipitation in determining MBL aerosol concentrations on longer time scales. ©2017. American Geophysical Union. All Rights Reserved."
"36163381900;7004584381;57194694512;15724763500;23051160600;7003505923;6701574983;","New Parameterizations for Neutral and Ion-Induced Sulfuric Acid-Water Particle Formation in Nucleation and Kinetic Regimes",2018,"10.1002/2017JD027429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042213205&doi=10.1002%2f2017JD027429&partnerID=40&md5=fd7922a9db97273bdb2115d19933e2e9","We have developed new parameterizations of electrically neutral homogeneous and ion-induced sulfuric acid-water particle formation for large ranges of environmental conditions, based on an improved model that has been validated against a particle formation rate data set produced by Cosmics Leaving OUtdoor Droplets (CLOUD) experiments at European Organization for Nuclear Research (CERN). The model uses a thermodynamically consistent version of the Classical Nucleation Theory normalized using quantum chemical data. Unlike the earlier parameterizations for H2SO4-H2O nucleation, the model is applicable to extreme dry conditions where the one-component sulfuric acid limit is approached. Parameterizations are presented for the critical cluster sulfuric acid mole fraction, the critical cluster radius, the total number of molecules in the critical cluster, and the particle formation rate. If the critical cluster contains only one sulfuric acid molecule, a simple formula for kinetic particle formation can be used: this threshold has also been parameterized. The parameterization for electrically neutral particle formation is valid for the following ranges: temperatures 165–400 K, sulfuric acid concentrations 104–1013 cm−3, and relative humidities 0.001–100%. The ion-induced particle formation parameterization is valid for temperatures 195–400 K, sulfuric acid concentrations 104–1016 cm−3, and relative humidities 10−5–100%. The new parameterizations are thus applicable for the full range of conditions in the Earth's atmosphere relevant for binary sulfuric acid-water particle formation, including both tropospheric and stratospheric conditions. They are also suitable for describing particle formation in the atmosphere of Venus. ©2017. American Geophysical Union. All Rights Reserved."
"57194379448;9276067100;6603902085;23470656000;7003644704;6603475273;57210457351;","Monitoring glacier albedo as a proxy to derive summer and annual surface mass balances from optical remote-sensing data",2018,"10.5194/tc-12-271-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041023286&doi=10.5194%2ftc-12-271-2018&partnerID=40&md5=f0aa34b62bfdef988a2d53f4896e3d92","Less than 0.25% of the 250000 glaciers inventoried in the Randolph Glacier Inventory (RGI V.5) are currently monitored with in situ measurements of surface mass balance. Increasing this archive is very challenging, especially using time-consuming methods based on in situ measurements, and complementary methods are required to quantify the surface mass balance of unmonitored glaciers. The current study relies on the so-called albedo method, based on the analysis of albedo maps retrieved from optical satellite imagery acquired since 2000 by the MODIS sensor, on board the TERRA satellite. Recent studies revealed substantial relationships between summer minimum glacier-wide surface albedo and annual surface mass balance, because this minimum surface albedo is directly related to the accumulation-area ratio and the equilibrium-line altitude. On the basis of 30 glaciers located in the French Alps where annual surface mass balance data are available, our study conducted on the period 2000-2015 confirms the robustness and reliability of the relationship between the summer minimum surface albedo and the annual surface mass balance. For the ablation season, the integrated summer surface albedo is significantly correlated with the summer surface mass balance of the six glaciers seasonally monitored. These results are promising to monitor both annual and summer glacier-wide surface mass balances of individual glaciers at a regional scale using optical satellite images. A sensitivity study on the computed cloud masks revealed a high confidence in the retrieved albedo maps, restricting the number of omission errors. Albedo retrieval artifacts have been detected for topographically incised glaciers, highlighting limitations in the shadow correction algorithm, although inter-annual comparisons are not affected by systematic errors. © 2018 Author(s)."
"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.
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).
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."
"24472400800;53878006900;26638618800;57203200427;8397494800;37037519900;7407104838;7102805852;35096299800;23095179000;57207008570;6506373162;36097570900;7404732357;9249627300;7005955015;","Response to marine cloud brightening in a multi-model ensemble",2018,"10.5194/acp-18-621-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040935384&doi=10.5194%2facp-18-621-2018&partnerID=40&md5=c421f80948498a8854998be0d8fdaca3","Here we show results from Earth system model simulations from the marine cloud brightening experiment G4cdnc of the Geoengineering Model Intercomparison Project (GeoMIP). The nine contributing models prescribe a 50g% increase in the cloud droplet number concentration (CDNC) of low clouds over the global oceans in an experiment dubbed G4cdnc, with the purpose of counteracting the radiative forcing due to anthropogenic greenhouse gases under the RCP4.5 scenario. The model ensemble median effective radiative forcing (ERF) amounts to g'1.9gWgmg'2, with a substantial inter-model spread of g'0.6 to g'2.5gWgmg'2. The large spread is partly related to the considerable differences in clouds and their representation between the models, with an underestimation of low clouds in several of the models. All models predict a statistically significant temperature decrease with a median of (for years 2020-2069) g'0.96 [g'0.17 to g'1.21]gK relative to the RCP4.5 scenario, with particularly strong cooling over low-latitude continents. Globally averaged there is a weak but significant precipitation decrease of g'2.35 [g'0.57 to g'2.96]g% due to a colder climate, but at low latitudes there is a 1.19g% increase over land. This increase is part of a circulation change where a strong negative top-of-atmosphere (TOA) shortwave forcing over subtropical oceans, caused by increased albedo associated with the increasing CDNC, is compensated for by rising motion and positive TOA longwave signals over adjacent land regions. © Author(s) 2018."
"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."
"56364931100;55480868800;7004027519;","Heterogeneous Oxidation of Particulate Methanesulfonic Acid by the Hydroxyl Radical: Kinetics and Atmospheric Implications",2018,"10.1021/acsearthspacechem.7b00114","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053740429&doi=10.1021%2facsearthspacechem.7b00114&partnerID=40&md5=16c293d71f716c114ef90ab08db4948e","Dimethyl sulfide (DMS) is a major source of sulfur to the marine boundary layer (MBL), and methanesulfonic acid (MSA) is one of its two main final oxidation products. MSA can participate in the nucleation and growth of aerosol particles, thereby affecting clouds and climate, and is used as a tracer of biological sulfur inputs. Unlike MSA, the other major oxidation product of DMS, sulfate, has several other sources, including volcanic and anthropogenic inputs. As a result, MSA to non-sea-salt sulfate (nss-sulfate) ratios are often used as proxies for biological activity; i.e., the MSA to nss-sulfate ratio in aerosol particles is used to estimate the marine biological contribution to nss-sulfate in the MBL. We present here a determination of the reactive uptake coefficient, γ, for the heterogeneous oxidation of MSA by hydroxyl radicals within deliquesced ammonium sulfate aerosol particles with an MSA mass fraction of 0.16 (a typical marine value) at room temperature. We find γ = 0.05 ± 0.03. For high ambient gas-phase concentrations of the hydroxyl radical, this uptake coefficient corresponds to an estimated lifetime against heterogeneous oxidation of only a few days for MSA in MBL aerosol particles. Significantly, for typical gas-phase and condensed concentrations of the hydroxyl radical, the lifetime estimated here for heterogeneous oxidation is shorter than that for condensed-phase oxidation of MSA. This finding should be taken into consideration when using MSA to nss-sulfate ratios as tracers for DMS and biological activity, especially for air masses that have been exposed to considerable photochemical oxidation. © 2017 American Chemical Society."
"6506848305;25031430500;36876405100;7005920812;7102696626;7102239370;57200319057;","The path to CAM6: Coupled simulations with CAM5.4 and CAM5.5",2018,"10.5194/gmd-11-235-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040767785&doi=10.5194%2fgmd-11-235-2018&partnerID=40&md5=34ecd3e50cba161004fb75f8cc4509b7","This paper documents coupled simulations of two developmental versions of the Community Atmosphere Model (CAM) towards CAM6. The configuration called CAM5.4 introduces new microphysics, aerosol, and ice nucleation changes, among others to CAM. The CAM5.5 configuration represents a more radical departure, as it uses an assumed probability density function (PDF)-based unified cloud parameterization to replace the turbulence, shallow convection, and warm cloud macrophysics in CAM. This assumed PDF method has been widely used in the last decade in atmosphere-only climate simulations but has never been documented in coupled mode. Here, we compare the simulated coupled climates of CAM5.4 and CAM5.5 and compare them to the control coupled simulation produced by CAM5.3. We find that CAM5.5 has lower cloud forcing biases when compared to the control simulations. Improvements are also seen in the simulated amplitude of the Niño-3.4 index, an improved representation of the diurnal cycle of precipitation, subtropical surface wind stresses, and double Intertropical Convergence Zone biases. Degradations are seen in Amazon precipitation as well as slightly colder sea surface temperatures and thinner Arctic sea ice. Simulation of the 20th century results in a credible simulation that ends slightly colder than the control coupled simulation. The authors find this is due to aerosol indirect effects that are slightly stronger in the new version of the model and propose a solution to ameliorate this. Overall, in these early coupled simulations, CAM5.5 produces a credible climate that is appropriate for science applications and is ready for integration into the National Center for Atmospheric Research's (NCAR's) next-generation climate model. © Author(s) 2018."
"55437450100;23486734100;55286185400;","The Diversity of Cloud Responses to Twentieth Century Sea Surface Temperatures",2018,"10.1002/2017GL075583","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040037344&doi=10.1002%2f2017GL075583&partnerID=40&md5=730a45b9153d8b686ca67fb6899cfd29","Low-level clouds are shown to be the conduit between the observed sea surface temperatures (SST) and large decadal fluctuations of the top of the atmosphere radiative imbalance. The influence of low-level clouds on the climate feedback is shown for global mean time series as well as particular geographic regions. The changes of clouds are found to be important for a midcentury period of high sensitivity and a late century period of low sensitivity. These conclusions are drawn from analysis of amip-piForcing simulations using three atmospheric general circulation models (AM2.1, AM3, and AM4.0). All three models confirm the importance of the relationship between the global climate sensitivity and the eastern Pacific trends of SST and low-level clouds. However, this work argues that the variability of the climate feedback parameter is not driven by stratocumulus-dominated regions in the eastern ocean basins, but rather by the cloudy response in the rest of the tropics. ©2017. The Authors."
"6602748142;","Using Stable Isotopes in Water Vapor to Diagnose Relationships Between Lower-Tropospheric Stability, Mixing, and Low-Cloud Cover Near the Island of Hawaii",2018,"10.1002/2017GL075770","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041000576&doi=10.1002%2f2017GL075770&partnerID=40&md5=f07433460a85491eb35efb1822a614d3","In situ measurements of water vapor isotopic composition from Mauna Loa, Hawaii, are merged with soundings from Hilo to show an inverse relationship between the estimated inversion strength (EIS) and isotopically derived measures of lower-tropospheric mixing. Remote sensing estimates of cloud fraction, cloud liquid water path, and cloud top pressure were all found to be higher (lower) under low (high) EIS. Inverse modeling of the isotopic data corresponding to terciles of EIS conditions provide quantitative constraints on the last-saturation temperatures and mixing fractions that govern the humidity above the trade inversion. The mixing fraction of water vapor transported from the boundary layer to Mauna Loa decreases with respect to EIS at a rate of about 3% K−1, corresponding to a mixing ratio decrease of 0.6 g kg−1 K−1. A last-saturation temperature of 240 K can match all observations. This approach can be applied in other settings and may be used to test models of low-cloud climate feedbacks. ©2017. American Geophysical Union. All Rights Reserved."
"56999327800;56611366900;38762392200;6603631763;","Using Long-Term Satellite Observations to Identify Sensitive Regimes and Active Regions of Aerosol Indirect Effects for Liquid Clouds Over Global Oceans",2018,"10.1002/2017JD027187","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040228340&doi=10.1002%2f2017JD027187&partnerID=40&md5=f1a8457f5ef93c5e210c943c3a9b9402","Long-term (1981–2011) satellite climate data records of clouds and aerosols are used to investigate the aerosol-cloud interaction of marine water cloud from a climatology perspective. Our focus is on identifying the regimes and regions where the aerosol indirect effects (AIEs) are evident in long-term averages over the global oceans through analyzing the correlation features between aerosol loading and the key cloud variables including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), cloud top height (CTH), and cloud top temperature (CTT). An aerosol optical thickness (AOT) range of 0.13 < AOT < 0.3 is identified as the sensitive regime of the conventional first AIE where CDER is more susceptible to AOT than the other cloud variables. The first AIE that manifests as the change of long-term averaged CDER appears only in limited oceanic regions. The signature of aerosol invigoration of water clouds as revealed by the increase of cloud cover fraction (CCF) and CTH with increasing AOT at the middle/high latitudes of both hemispheres is identified for a pristine atmosphere (AOT < 0.08). Aerosol invigoration signature is also revealed by the concurrent increase of CDER, COD, and CWP with increasing AOT for a polluted marine atmosphere (AOT > 0.3) in the tropical convergence zones. The regions where the second AIE is likely to manifest in the CCF change are limited to several oceanic areas with high CCF of the warm water clouds near the western coasts of continents. The second AIE signature as represented by the reduction of the precipitation efficiency with increasing AOT is more likely to be observed in the AOT regime of 0.08 < AOT < 0.4. The corresponding AIE active regions manifested themselves as the decline of the precipitation efficiency are mainly limited to the oceanic areas downwind of continental aerosols. The sensitive regime of the conventional AIE identified in this observational study is likely associated with the transitional regime from the aerosol-limited regime to the updraft-limited regime identified for aerosol-cloud interaction in cloud model simulations. Published 2017. This article is a US Government work and is in the public domain in the USA."
"8718425100;57212989384;13402933200;57189359941;55817344400;57189365822;7404678955;36187387300;57191712049;","Process-level improvements in CMIP5 models and their impact on tropical variability, the Southern Ocean, and monsoons",2018,"10.5194/esd-9-33-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040793014&doi=10.5194%2fesd-9-33-2018&partnerID=40&md5=5cd81173c80f4387abf9cdc076d0019d","The performance of updated versions of the four earth system models (ESMs) CNRM, EC-Earth, HadGEM, and MPI-ESM is assessed in comparison to their predecessor versions used in Phase 5 of the Coupled Model Intercomparison Project. The Earth System Model Evaluation Tool (ESMValTool) is applied to evaluate selected climate phenomena in the models against observations. This is the first systematic application of the ESMValTool to assess and document the progress made during an extensive model development and improvement project. This study focuses on the South Asian monsoon (SAM) and the West African monsoon (WAM), the coupled equatorial climate, and Southern Ocean clouds and radiation, which are known to exhibit systematic biases in present-day ESMs. The analysis shows that the tropical precipitation in three out of four models is clearly improved. Two of three updated coupled models show an improved representation of tropical sea surface temperatures with one coupled model not exhibiting a double Intertropical Convergence Zone (ITCZ). Simulated cloud amounts and cloud-radiation interactions are improved over the Southern Ocean. Improvements are also seen in the simulation of the SAM and WAM, although systematic biases remain in regional details and the timing of monsoon rainfall. Analysis of simulations with EC-Earth at different horizontal resolutions from T159 up to T1279 shows that the synoptic-scale variability in precipitation over the SAM and WAM regions improves with higher model resolution. The results suggest that the reasonably good agreement of modeled and observed mean WAM and SAM rainfall in lower-resolution models may be a result of unrealistic intensity distributions."
"57188924386;57203030873;6603925960;57193321831;56297151300;","Isolating the Liquid Cloud Response to Recent Arctic Sea Ice Variability Using Spaceborne Lidar Observations",2018,"10.1002/2017JD027248","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040225886&doi=10.1002%2f2017JD027248&partnerID=40&md5=7d92617f3abc5770dbe5024dfbea5b5f","While the radiative influence of clouds on Arctic sea ice is known, the influence of sea ice cover on Arctic clouds is challenging to detect, separate from atmospheric circulation, and attribute to human activities. Providing observational constraints on the two-way relationship between sea ice cover and Arctic clouds is important for predicting the rate of future sea ice loss. Here we use 8 years of CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) spaceborne lidar observations from 2008 to 2015 to analyze Arctic cloud profiles over sea ice and over open water. Using a novel surface mask to restrict our analysis to where sea ice concentration varies, we isolate the influence of sea ice cover on Arctic Ocean clouds. The study focuses on clouds containing liquid water because liquid-containing clouds are the most important cloud type for radiative fluxes and therefore for sea ice melt and growth. Summer is the only season with no observed cloud response to sea ice cover variability: liquid cloud profiles are nearly identical over sea ice and over open water. These results suggest that shortwave summer cloud feedbacks do not slow long-term summer sea ice loss. In contrast, more liquid clouds are observed over open water than over sea ice in the winter, spring, and fall in the 8 year mean and in each individual year. Observed fall sea ice loss cannot be explained by natural variability alone, which suggests that observed increases in fall Arctic cloud cover over newly open water are linked to human activities. ©2018. American Geophysical Union. All Rights Reserved."
"55877698400;55796506900;56276311500;7410070663;","On Effective Radiative Forcing of Partial Internally and Externally Mixed Aerosols and Their Effects on Global Climate",2018,"10.1002/2017JD027603","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041038802&doi=10.1002%2f2017JD027603&partnerID=40&md5=3d5b5a5ef3ed54bd8d03e9f59cae49a0","The total effective radiative forcing (ERF) due to partial internally mixed (PIM) and externally mixed (EM) anthropogenic aerosols, as well as their climatic effects since the year of 1850, was evaluated and compared using the aerosol-climate online coupled model of BCC_AGCM2.0_CUACE/Aero. The influences of internal mixing (IM) on aerosol hygroscopicity parameter, optical properties, and concentration were considered. Generally, IM could markedly weaken the negative ERF and cooling effects of anthropogenic aerosols. The global annual mean ERF of EM anthropogenic aerosols from 1850 to 2010 was −1.87 W m−2, of which the aerosol-radiation interactive ERF (ERFari) and aerosol-cloud interactive ERF (ERFaci) were −0.49 and −1.38 W m−2, respectively. The global annual mean ERF due to PIM anthropogenic aerosols from 1850 to 2010 was −1.23 W m−2, with ERFari and ERFaci of −0.23 and −1.01 W m−2, respectively. The global annual mean surface temperature and water evaporation and precipitation were reduced by 1.74 K and 0.14 mm d−1 for EM scheme and 1.28 K and 0.11 mm d−1 for PIM scheme, respectively. However, the relative humidity near the surface was slightly increased for both mixing cases. The Intertropical Convergence Zone was southwardly shifted for both EM and PIM cases but was less southwardly shifted in PIM scheme due to the less reduction in atmospheric temperature in the midlatitude and low latitude of the Northern Hemisphere. ©2017. American Geophysical Union. All Rights Reserved."
"36637539100;7006399667;15724418700;","Convectively Driven Tropopause-Level Cooling and Its Influences on Stratospheric Moisture",2018,"10.1002/2017JD027080","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040640638&doi=10.1002%2f2017JD027080&partnerID=40&md5=6154d278317c35d2715c09525acdecfe","Characteristics of the tropopause-level cooling associated with tropical deep convection are examined using CloudSat radar and Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS radio occultation measurements. Extreme deep convection is sampled based on the cloud top height (>17 km) from CloudSat, and colocated temperature profiles from COSMIC are composited around the deep convection. Response of moisture to the tropopause-level cooling is also examined in the upper troposphere and lower stratosphere using microwave limb sounder measurements. The composite temperature shows an anomalous warming in the troposphere and a significant cooling near the tropopause (at 16–19 km) when deep convection occurs over the western Pacific, particularly during periods with active Madden-Julian Oscillation (MJO). The composite of the tropopause cooling has a large horizontal scale (~6,000 km in longitude) with minimum temperature anomaly of ~ −2 K, and it lasts more than 2 weeks with support of mesoscale convective clusters embedded within the envelope of the MJO. The water vapor anomalies show strong correlation with the temperature anomalies (i.e., dry anomaly in the cold anomaly), showing that the convectively driven tropopause cooling actively dehydrate the lower stratosphere in the western Pacific region. The moisture is also affected by anomalous Matsuno-Gill-type circulation associated with the cold anomaly, in which dry air spreads over a wide range in the tropical tropopause layer (TTL). These results suggest that convectively driven tropopause cooling and associated transient circulation play an important role in the large-scale dehydration process in the TTL. ©2017. American Geophysical Union. All Rights Reserved."
"7003928365;55110642200;27567902000;57020299300;56715015600;23111070800;57031456600;13609774500;55627876965;57197759798;6506329502;57197760915;55420017500;","Late Middle Miocene volcanism in Northwest Borneo, Southeast Asia: Implications for tectonics, paleoclimate and stratigraphic marker",2018,"10.1016/j.palaeo.2017.10.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034591158&doi=10.1016%2fj.palaeo.2017.10.022&partnerID=40&md5=d0b03487b57e70ee21b1712da067b966","Explosive volcanic events often produce pyroclastic materials that can be recognized from the geological record. These discrete pyroclastics form regional marker beds. Here we report the occurrence of a tephra layer interbedded within very thick coal beds near Mukah, Sarawak, Borneo. Traceable for tens of kilometers in the Mukah area of Sarawak, this tephra layer can be considered as regional stratigraphic marker with precise chronostratigraphic control. Systematic sedimentological, mineralogical, geochemical and zircon U–Pb geochronological studies have revealed a major effusive volcanic event during the latest Middle Miocene, presumably contemporaneous and/or related to a magmatic event of an earlier phase of the Mt. Kinabalu pluton or magmatism in West Sarawak or East Sabah. The volcanic event had promoted catastrophic flooding of coastal swamps and fall-out from the ash clouds that formed a regionally monotonous tephra layer across the Serravallian- Tortonian boundary. In conjunction with the regional occurrences of trap rocks, structural trends and known tectonic events, we constrained the regional depositional environments, and climate. The tephra layer was deposited in a coastal plain-swamp,- seasonal, shallow, high-moderate energy, fluvial channel-lacustrine environmental setting, wherein atmospheric fallout and eroded material from regoliths formed over older basement and volcanic rocks of the hinterland which were mixed to produce the tephra layer. This tephra layer is sandwiched between the very thick coal beds. A pre-existent volcanic chamber that was active for a long time, also experienced periodic explosive activity from probably the same magma chamber and conduit and including a major explosive activity that recycled early-formed crystals and felsic magma (rhyolite-dacite) during the major effusive event are also recognized. Our findings provide robust evidence for the prevalence of intensive chemical weathering under a wet-humid climate, and relative tectonic quiescence before the major effusive event, and the existence of vast, monotonously gently-sloping coastal plains and luxuriant vegetation akin to the present. © 2017 Elsevier B.V."
"7403276033;57214087387;7006827027;35585284200;6602499262;16174234500;","Synoptic ozone, cloud reflectivity, and erythemal irradiance from sunrise to sunset for the whole earth as viewed by the DSCOVR spacecraft from the earth-sun Lagrange 1 orbit",2018,"10.5194/amt-11-177-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040730307&doi=10.5194%2famt-11-177-2018&partnerID=40&md5=74fc93f7e48f8a463e0aa49464b4cada","EPIC (Earth Polychromatic Imaging Camera) on board the DSCOVR (Deep Space Climate Observatory) spacecraft is the first earth science instrument located near the earth-sun gravitational plus centrifugal force balance point, Lagrange 1. EPIC measures earth-reflected radiances in 10 wavelength channels ranging from 317.5 to 779.5 nm. Of these channels, four are in the UV range 317.5, 325, 340, and 388 nm, which are used to retrieve O3, 388 nm scene reflectivity (LER: Lambert equivalent reflectivity), SO2, and aerosol properties. These new synoptic quantities are retrieved for the entire sunlit globe from sunrise to sunset multiple times per day as the earth rotates in EPIC's field of view. Retrieved ozone amounts agree with ground-based measurements and satellite data to within 3 %. The ozone amounts and LER are combined to derive the erythemal irradiance for the earth's entire sunlit surface at a nadir resolution of 18×18 km2 using a computationally efficient approximation to a radiative transfer calculation of irradiance. The results show very high summertime values of the UV index (UVI) in the Andes and Himalayas (greater than 18), and high values of UVI near the Equator at equinox. © Author(s) 2018."
"55332129600;57205867148;13402835300;","The Cloud Feedback Model Intercomparison Project Observational Simulator Package: Version 2",2018,"10.5194/gmd-11-77-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041338893&doi=10.5194%2fgmd-11-77-2018&partnerID=40&md5=e3ee705cf1a904bebc7de02cd5656f42","The Cloud Feedback Model Intercomparison Project Observational Simulator Package (COSP) gathers together a collection of observation proxies or satellite simulators
that translate model-simulated cloud properties to synthetic observations as would be obtained by a range of satellite observing systems. This paper introduces COSP2, an evolution focusing on more explicit and consistent separation between host model, coupling infrastructure, and individual observing proxies. Revisions also enhance flexibility by allowing for model-specific representation of sub-grid-scale cloudiness, provide greater clarity by clearly separating tasks, support greater use of shared code and data including shared inputs across simulators, and follow more uniform software standards to simplify implementation across a wide range of platforms. The complete package including a testing suite is freely available. © Author(s) 2018."
"57207870010;56682032300;13405658600;36867775200;6603156461;","Machine learning to predict the global distribution of aerosol mixing state metrics",2018,"10.3390/atmos9010015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040237561&doi=10.3390%2fatmos9010015&partnerID=40&md5=aa275e13faf9e96510446aa4135b5001","Atmospheric aerosols are evolving mixtures of chemical species. In global climate models (GCMs), this ""aerosol mixing state"" is represented in a highly simplified manner. This can introduce errors in the estimates of climate-relevant aerosol properties, such as the concentration of cloud condensation nuclei. The goal for this study is to determine a global spatial distribution of aerosol mixing state with respect to hygroscopicity, as quantified by the mixing state metric χ. In this way, areas can be identified where the external or internal mixture assumption is more appropriate. We used the output of a large ensemble of particle-resolved box model simulations in conjunction with machine learning techniques to train a model of the mixing state metric c. This lower-order model for χ uses as inputs only variables known to GCMs, enabling us to create a global map of χ based on GCM data. We found that χ varied between 20% and nearly 100%, and we quantified how this depended on particle diameter, location, and time of the year. This framework demonstrates how machine learning can be applied to bridge the gap between detailed process modeling and a large-scale climate model. © 2017 by the author."
"57197760821;13403899000;6603933756;6602624109;6602341538;57196496271;6602638842;14830593700;6603343882;27867527200;36647270000;35569803200;7402480218;","Ultraviolet radiation modelling from ground-based and satellite measurements on Reunion Island, southern tropics",2018,"10.5194/acp-18-227-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040459602&doi=10.5194%2facp-18-227-2018&partnerID=40&md5=34301aa2ce7f4114835b7b1a3a3c33c4","Surface ultraviolet radiation (SUR) is not an increasing concern after the implementation of the Montreal Protocol and the recovery of the ozone layer (Morgenstern et al., 2008). However, large uncertainties remain in the prediction of future changes of SUR (Bais et al., 2015). Several studies pointed out that UV-B impacts the biosphere (Erickson et al., 2015), especially the aquatic system, which plays a central part in the biogeochemical cycle (Hader et al., 2007). It can affect phytoplankton productivity (Smith and Cullen, 1995). This influence can result in either positive or negative feedback on climate (Zepp et al., 2007).
Global circulation model simulations predict an acceleration of the Brewer-Dobson circulation over the next century (Butchart, 2014), which would lead to a decrease in ozone levels in the tropics and an enhancement at higher latitudes (Hegglin and Shepherd, 2009). Reunion Island is located in the tropics (21°S, 55°E), in a part of the world where the amount of ozone in the ozone column is naturally low. In addition, this island is mountainous and the marine atmosphere is often clean with low aerosol concentrations. Thus, measurements show much higher SUR than at other sites at the same latitude or at midlatitudes. Ground-based measurements of SUR have been taken on Reunion Island by a Bentham DTMc300 spectroradiometer since 2009. This instrument is affiliated with the Network for the Detection of Atmospheric Composition Change (NDACC). In order to quantify the future evolution of SUR in the tropics, it is necessary to validate a model against present observations. This study is designed to be a preliminary parametric and sensitivity study of SUR modelling in the tropics.
We developed a local parameterisation using the Tropospheric Ultraviolet and Visible Model (TUV; Madronich, 1993) and compared the output of TUV to multiple years of Bentham spectral measurements. This comparison started in early 2009 and continued until 2016.
Only clear-sky SUR was modelled, so we needed to sort out the clear-sky measurements. We used two methods to detect cloudy conditions: the first was based on an observer's hourly report on the sky cover, while the second was based on applying Long and Ackerman (2000)'s algorithm to broadband pyranometer data to obtain the cloud fraction and then discriminating clear-sky windows on SUR measurements. Long et al. (2006)'s algorithm, with the co-located pyranometer data, gave better results for clear-sky filtering than the observer's report.
Multiple model inputs were tested to evaluate the model sensitivity to different parameters such as total ozone column, aerosol optical properties, extraterrestrial spectrum or ozone cross section. For total column ozone, we used ground-based measurements from the SAOZ (Système d'Analyse par Observation Zénithale) spectrometer and satellite measurements from the OMI and SBUV instruments, while ozone profiles were derived from radio-soundings and the MLS ozone product. Aerosol optical properties came from a local aerosol climatology established using a Cimel photometer. Since the mean difference between various inputs of total ozone column was small, the corresponding response on UVI modelling was also quite small, at about 1%. The radiative amplification factor of total ozone column on UVI was also compared for observations and the model. Finally, we were able to estimate UVI on Reunion Island with, at best, a mean relative difference of about 0.5%, compared to clear-sky observations."
"57200208164;56384704800;55802246600;57200055610;57200201534;55494211100;57202299549;55717074000;7406500188;","Investigation of short-term effective radiative forcing of fire aerosols over North America using nudged hindcast ensembles",2018,"10.5194/acp-18-31-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040176667&doi=10.5194%2facp-18-31-2018&partnerID=40&md5=c49422027a74fe78db85b7ed46a3f279","Aerosols from fire emissions can potentially have large impact on clouds and radiation. However, fire aerosol sources are often intermittent, and their effect on weather and climate is difficult to quantify. Here we investigated the short-term effective radiative forcing of fire aerosols using the global aerosol-climate model Community Atmosphere Model version 5 (CAM5). Different from previous studies, we used nudged hindcast ensembles to quantify the forcing uncertainty due to the chaotic response to small perturbations in the atmosphere state. Daily mean emissions from three fire inventories were used to consider the uncertainty in emission strength and injection heights. The simulated aerosol optical depth (AOD) and mass concentrations were evaluated against in situ measurements and reanalysis data. Overall, the results show the model has reasonably good predicting skills. Short (10-day) nudged ensemble simulations were then performed with and without fire emissions to estimate the effective radiative forcing. Results show fire aerosols have large effects on both liquid and ice clouds over the two selected regions in April 2009. Ensemble mean results show strong negative shortwave cloud radiative effect (SCRE) over almost the entirety of southern Mexico, with a 10-day regional mean value of -3.0 W m-2. Over the central US, the SCRE is positive in the north but negative in the south, and the regional mean SCRE is small (-0.56 W m-2). For the 10-day average, we found a large ensemble spread of regional mean shortwave cloud radiative effect over southern Mexico (15.6 % of the corresponding ensemble mean) and the central US (64.3 %), despite the regional mean AOD time series being almost indistinguishable during the 10-day period. Moreover, the ensemble spread is much larger when using daily averages instead of 10-day averages. This demonstrates the importance of using a large ensemble of simulations to estimate the short-term aerosol effective radiative forcing. © Author(s) 2018."
"55682930400;36106335800;57195681934;7501627905;6701762451;","How uncertainty in field measurements of ice nucleating particles influences modeled cloud forcing",2018,"10.1175/JAS-D-17-0089.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040952552&doi=10.1175%2fJAS-D-17-0089.1&partnerID=40&md5=17779c3132f82c6b9afb725e851efbbe","Field and laboratory measurements using continuous flow diffusion chambers (CFDCs) have been used to construct parameterizations of the number of ice nucleating particles (INPs) in mixed-phase and completely glaciated clouds in weather and climate models. Because of flow nonidealities, CFDC measurements are subject to systematic low biases. Here, the authors investigate the effects of this undercounting bias on simulated cloud forcing in a global climate model. The authors assess the influence of measurement variability by constructing a stochastic parameterization framework to endogenize measurement uncertainty. The authors find that simulated anthropogenic longwave ice-bearing cloud forcing in a global climate model can vary up to 0.8 W m-2 and can change sign from positive to negative within the experimentally constrained bias range. Considering the variability in the undercounting bias, in a range consistent with recent experiments, leads to a larger negative cloud forcing than that when the variability is ignored and only a constant bias is assumed. © 2018 American Meteorological Society."
"52464731300;7401936984;7402064802;7101959253;6603431534;7006204393;8859530100;57211721176;55332129600;13402835300;56763174500;16679271700;36342344200;57198616562;14019153700;20433705700;26423829900;","The ARM cloud radar simulator for global climate models bridging field data and climate models",2018,"10.1175/BAMS-D-16-0258.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041380276&doi=10.1175%2fBAMS-D-16-0258.1&partnerID=40&md5=335c918caf557a9d25baceaf8609e082",[No abstract available]
"7202660824;7403288995;55746365900;26645289600;7402064802;56537463000;8525144100;22959252400;","On the emergent constraints of climate sensitivity",2018,"10.1175/JCLI-D-17-0482.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040610855&doi=10.1175%2fJCLI-D-17-0482.1&partnerID=40&md5=7cdd7d441265e8d5448bd6ba9c0788e3","Differences among climate models in equilibrium climate sensitivity (ECS; the equilibrium surface temperature response to a doubling of atmospheric CO2) remain a significant barrier to the accurate assessment of societally important impacts of climate change. Relationships between ECS and observable metrics of the current climate in model ensembles, so-called emergent constraints, have been used to constrain ECS. Here a statistical method (including a backward selection process) is employed to achieve a better statistical understanding of the connections between four recently proposed emergent constraint metrics and individual feedbacks influencing ECS. The relationship between each metric and ECS is largely attributable to a statistical connection with shortwave low cloud feedback, the leading cause of intermodel ECS spread. This result bolsters confidence in some of the metrics, which had assumed such a connection in the first place. Additional analysis is conducted with a few thousand artificial metrics that are randomly generated but are well correlated with ECS. The relationships between the contrived metrics and ECS can also be linked statistically to shortwave cloud feedback. Thus, any proposed or forthcoming ECS constraint based on the current generation of climate models should be viewed as a potential constraint on shortwave cloud feedback, and physical links with that feedback should be investigated to verify that the constraint is real. In addition, any proposed ECS constraint should not be taken at face value since other factors influencing ECS besides shortwave cloud feedback could be systematically biased in the models. © 2018 American Meteorological Society."
"24329376600;7201485519;","The dependence of global cloud and lapse rate feedbacks on the spatial structure of tropical pacific warming",2018,"10.1175/JCLI-D-17-0087.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040608943&doi=10.1175%2fJCLI-D-17-0087.1&partnerID=40&md5=a6c012de5c8979cd4c6cb2b670e6efd1","An atmospheric general circulation model (AGCM) is forced with patterns of observed sea surface temperature (SST) change and those output from atmosphere-ocean GCM (AOGCM) climate change simulations to demonstrate a strong dependence of climate feedback on the spatial structure of surface temperature change. Cloud and lapse rate feedbacks are found to vary the most, depending strongly on the pattern of tropical Pacific SST change. When warming is focused in the southeast tropical Pacific-a region of climatological subsidence and extensive marine low cloud cover-warming reduces the lower-tropospheric stability (LTS) and low cloud cover but is largely trapped under an inversion and hence has little remote effect. The net result is a relatively weak negative lapse rate feedback and a large positive cloud feedback. In contrast, when warming is weak in the southeast tropical Pacific and enhanced in the west tropical Pacific-a strong convective region-warming is efficiently transported throughout the free troposphere. The increased atmospheric stability results in a strong negative lapse rate feedback and increases the LTS in low cloud regions, resulting in a low cloud feedback of weak magnitude. These mechanisms help explain why climate feedback and sensitivity change on multidecadal time scales in AOGCM abrupt4xCO2 simulations and are different from those seen in AGCM experiments forced with observed historical SST changes. From the physical understanding developed here, one should expect unusually negative radiative feedbacks and low effective climate sensitivities to be diagnosed from real-world variations in radiative fluxes and temperature over decades in which the eastern Pacific has lacked warming. © 2018 American Meteorological Society."
"7005968859;8586682800;57203053317;","100 years of progress in cloud physics, aerosols, and aerosol chemistry research",2018,"10.1175/AMSMONOGRAPHS-D-18-0024.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083359556&doi=10.1175%2fAMSMONOGRAPHS-D-18-0024.1&partnerID=40&md5=ffdaab130a54dae0e6db7516cad3aa45","This chapter reviews the history of the discovery of cloud nuclei and their impacts on cloud microphysics and the climate system. Pioneers including John Aitken, Sir John Mason, Hilding Köhler, Christian Junge, Sean Twomey, and Kenneth Whitby laid the foundations of the field. Through their contributions and those of many others, rapid progress has been made in the last 100 years in understanding the sources, evolution, and composition of the atmospheric aerosol, the interactions of particles with atmospheric water vapor, and cloud microphysical processes. Major breakthroughs in measurement capabilities and in theoretical understanding have elucidated the characteristics of cloud condensation nuclei and ice nucleating particles and the role these play in shaping cloud microphysical properties and the formation of precipitation. Despite these advances, not all their impacts on cloud formation and evolution have been resolved. The resulting radiative forcing on the climate system due to aerosol–cloud interactions remains an unacceptably large uncertainty in future climate projections. Process-level understanding of aerosol–cloud interactions remains insufficient to support tech-nological mitigation strategies such as intentional weather modification or geoengineering to accelerating Earth-system-wide changes in temperature and weather patterns. © 2019 American Meteorological Society."
"57201133722;57201135163;","Simulation of the brightness temperatures observed by the visible infrared imaging radiometer suite instrument",2018,"10.1117/1.JRS.12.016032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043524659&doi=10.1117%2f1.JRS.12.016032&partnerID=40&md5=f2da0c77f2ff31b9e244aff7b3842f3e","Clouds play a large role in the Earth's global energy budget, but the impact of cirrus clouds is still widely questioned and researched. Cirrus clouds reside high in the atmosphere and due to cold temperatures are comprised of ice crystals. Gaining a better understanding of ice cloud optical properties and the distribution of cirrus clouds provides an explanation for the contribution of cirrus clouds to the global energy budget. Using radiative transfer models (RTMs), accurate simulations of cirrus clouds can enhance the understanding of the global energy budget as well as improve the use of global climate models. A newer, faster RTM such as the visible infrared imaging radiometer suite (VIIRS) fast radiative transfer model (VFRTM) is compared to a rigorous RTM such as the line-by-line radiative transfer model plus the discrete ordinates radiative transfer program. By comparing brightness temperature (BT) simulations from both models, the accuracy of the VFRTM can be obtained. This study shows root-mean-square error <0.2 K for BT difference using reanalysis data for atmospheric profiles and updated ice particle habit information from the moderate-resolution imaging spectroradiometer collection 6. At a higher resolution, the simulated results of the VFRTM are compared to the observations of VIIRS resulting in a <1.5 % error from the VFRTM for all cases. The VFRTM is validated and is an appropriate RTM to use for global cloud retrievals. © 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)."
"56116695000;7601492669;57207330028;","Intercomparison of cloud amount datasets in the kuroshio region over the east China sea",2018,"10.2151/jmsj.2018-018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045216201&doi=10.2151%2fjmsj.2018-018&partnerID=40&md5=5027cbc2e5f40e89d0c7b069873d9e2b","The cloud variability and regime transition from stratocumulus to cumulus across the sea surface temperature front in the Kuroshio region over the East China Sea are important regional climate features and may affect the Earth’s energy balance. However, because of large uncertainties among available cloud products, it is unclear which cloud datasets are more reliable for use in studying the regional cloud features and in validating cloud simulations in the region by climate models. In this study, the monthly low cloud amount (LCA) and total cloud amount (TCA) datasets in the region from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), Moderate-resolution Imaging Spectroradiometer (MODIS), and International Comprehensive Ocean- Atmosphere Data Set (ICOADS) are validated against the combined product of CloudSat + CALIPSO (CC) in terms of consistency and discrepancy in the climatologically mean, seasonal cycle, and interannual variation. The results show that LCA and TCA derived from MODIS and CALIPSO present relatively high consistency with CC data in the climatological annual mean and show similar behaviors in seasonal cycle. The consistency in LCA between the three datasets and the CC is generally good in cold seasons (winter, spring, and fall) but poor in summer. MODIS shows the best agreement with CC in fall, with a correlation coefficient of 0.77 at a confidence level over 99 %. CALIPSO and MODIS can provide a competitive description of TCA in all seasons, and ICOADS is good in terms of the climatological seasonal mean of TCA in winter only. Moreover, the interannual complivariation of LCA and TCA from all datasets is highly correlated with that from CC in both winter and spring with the Matching Score ranging between 2/3 and 1. Further analysis with long-term data suggests that both LCA and TCA from ICOADS and MODIS can be good references for studies of cloud interannual variability in the region. © The Author(s) 2018."
"56078955700;56788002200;56809005800;7004041202;","Adjoint-Based Climate Model Tuning: Application to the Planet Simulator",2018,"10.1002/2017MS001194","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041074703&doi=10.1002%2f2017MS001194&partnerID=40&md5=346bde9bf7b14722e518844475aced4d","The adjoint method is used to calibrate the medium complexity climate model “Planet Simulator” through parameter estimation. Identical twin experiments demonstrate that this method can retrieve default values of the control parameters when using a long assimilation window of the order of 2 months. Chaos synchronization through nudging, required to overcome limits in the temporal assimilation window in the adjoint method, is employed successfully to reach this assimilation window length. When assimilating ERA-Interim reanalysis data, the observations of air temperature and the radiative fluxes are the most important data for adjusting the control parameters. The global mean net longwave fluxes at the surface and at the top of the atmosphere are significantly improved by tuning two model parameters controlling the absorption of clouds and water vapor. The global mean net shortwave radiation at the surface is improved by optimizing three model parameters controlling cloud optical properties. The optimized parameters improve the free model (without nudging terms) simulation in a way similar to that in the assimilation experiments. Results suggest a promising way for tuning uncertain parameters in nonlinear coupled climate models. © 2018. The Authors."
"57193831923;12040335900;25723417400;56537463000;7404829395;","Observational estimation of radiative feedback to surface air temperature over Northern High Latitudes",2018,"10.1007/s00382-017-3629-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016943999&doi=10.1007%2fs00382-017-3629-6&partnerID=40&md5=1354df49178cda0606834701ca6036a3","The high-latitude climate system contains complicated, but largely veiled physical feedback processes. Climate predictions remain uncertain, especially for the Northern High Latitudes (NHL; north of 60°N), and observational constraint on climate modeling is vital. This study estimates local radiative feedbacks for NHL based on the CERES/Terra satellite observations during March 2000–November 2014. The local shortwave (SW) and longwave (LW) radiative feedback parameters are calculated from linear regression of radiative fluxes at the top of the atmosphere on surface air temperatures. These parameters are estimated by the de-seasonalization and 12-month moving average of the radiative fluxes over NHL. The estimated magnitudes of the SW and the LW radiative feedbacks in NHL are 1.88 ± 0.73 and 2.38 ± 0.59 W m−2 K−1, respectively. The parameters are further decomposed into individual feedback components associated with surface albedo, water vapor, lapse rate, and clouds, as a product of the change in climate variables from ERA-Interim reanalysis estimates and their pre-calculated radiative kernels. The results reveal the significant role of clouds in reducing the surface albedo feedback (1.13 ± 0.44 W m−2 K−1 in the cloud-free condition, and 0.49 ± 0.30 W m−2 K−1 in the all-sky condition), while the lapse rate feedback is predominant in LW radiation (1.33 ± 0.18 W m−2 K−1). However, a large portion of the local SW and LW radiative feedbacks were not simply explained by the sum of these individual feedbacks. © 2017, Springer-Verlag Berlin Heidelberg."
"55933348800;6602630273;7402319036;","A Framework for Prioritizing Areas for Conservation in Tropical Montane Cloud Forests",2018,"10.1080/11956860.2017.1419787","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041963973&doi=10.1080%2f11956860.2017.1419787&partnerID=40&md5=31a6b185f9d260c3b46333d56804d873","Tropical cloud forests are under severe distress, as deforestation leads to forest fragmentation and degradation. This represents a severe threat to small-ranged, forest-dependent species, as they are at risk of losing habitat and connectivity between populations. These detrimental effects are aggravated by upslope range shifts caused by climate change, as further habitat loss is expected. To mitigate these threats, the preservation of habitat and connectivity becomes necessary. Here, we present a novel framework for identifying future key areas offering highquality habitat and connectivity. The framework combines data on the composition of forests, their configuration in the landscape, as well as dispersal abilities and altitudinal range for several focal species. Importantly, the framework integrates projections of future range shifts. Thus, it prioritizes a network of areas with high-conservation value robust to climate change. We applied the framework to the cloud forest in Ecuador, using two endemic bird species to identify areas for mitigating the adverse effects of climate change. Our approach allows targeting reforestation measures effectively to areas of high-conservation value. The framework presented here can be applied to different ecosystems and geographical locations, and therefore contribute to making informed decisions about the implementation of robust conservation measures. © 2017 Université Laval."
"23977679300;6701819583;14119516800;7006860287;7004368198;","Bayesian cloud detection for 37 years of Advanced Very High Resolution Radiometer (AVHRR) Global Area Coverage (GAC) data",2018,"10.3390/rs10010097","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040708015&doi=10.3390%2frs10010097&partnerID=40&md5=c348052c4eeae27b2b9d3049e362d410","Cloud detection is a source of significant errors in retrieval of sea surface temperature (SST).We apply a Bayesian cloud detection scheme to 37 years of Advanced Very High Resolution Radiometer (AVHRR) Global Area Coverage (GAC) data, which is an important source of multi-decadal global SST information. The Bayesian scheme calculates a probability of clear-sky for each image pixel, conditional on the satellite observations and prior probability. We compare the cloud detection performance to the operational Clouds from AVHRR Extended algorithm (CLAVR-x), as a measure of improvement from reduced cloud-related errors. To do this we use sea surface temperature differences between satellite retrievals and in situ observations from drifting buoys and the Global Tropical Moored Buoy Array (GTMBA). The Bayesian scheme reduces the absolute difference between the mean and median SST biases and reduces the standard deviation of the SST differences by ~10% for both daytime and nighttime retrievals. These reductions are indicative of removing cloud contaminated outliers in the distribution, as these fall only on one side of the distribution forming a cold tail. At a probability threshold of 0.9 typically used to determine a binary cloud mask for SST retrieval, the Bayesian mask also reduces the robust standard deviation by ~5-10% during the day, in comparison with the operational cloud mask. This shows an improvement in the central distribution of SST differences for daytime retrievals."
"56798441100;36606783400;7004351010;","Aerosols characteristics, trends and their climatic implications over northeast india and adjoining South Asia",2018,"10.1002/joc.5240","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045913681&doi=10.1002%2fjoc.5240&partnerID=40&md5=4ee7846f4acd2d05e11ac65bfe7e498e","Aerosol characteristics and climatic implications derived for selected locations of the north-eastern region of India and adjoining locations Thimphu (THM), Dhaka (DAC) and Banmauk between 22-30°N and 88-98°E are reported. The region is found to reveal a distinct spatio-temporal variability in aerosol distribution, with highest climatological mean aerosol optical depth at 550 nm (AOD550) at DAC (0.65 ± 0.07) and lowest at the high altitude location THM (0.19 ± 0.02). Seasonally the maximum AOD550 is observed in the pre-monsoon season. Moderate resolution imaging spectroradiometer Level-3 Collection 6 AOD550 and Ångström exponent (AE) exhibit a significant and simultaneous increasing trend in the range of ∼0.003 year−1 to 0.012 year−1 and ∼−0.001 year−1 to 0.020 year−1, respectively, during the period 2001-2014. Together with AE, increasing trend of total ozone mapping spectrometer and ozone monitoring instrument-retrieved aerosol index (∼0.001 year−1 to 0.007 year−1 during 1979-2014) signifies an increase in anthropogenic aerosol loading, leading to an increase in number density of cloud condensation nuclei and decrease/increase of cloud effective radius /cloud optical depth (COD). This is further associated with overall decreasing trends of rainfall rate over this complex monsoon region. A slow increase in maximum temperature (Tmax) (∼0.008 ∘C year−1 to 0.049 ∘C year−1) compared to that in minimum temperature (Tmin) (∼0.007 ∘C year−1 to 0.068 ∘C year−1) is attributed to solar dimming due to increasing aerosol loading and COD (∼0.056 year−1 to 0.15 year−1). A decrease in high-level cloud (CODhigh) counteracts decreasing trends of ground reaching solar radiation over a few locations, including Dibrugarh. This study is important from an aerosol radiation interaction and aerosol cloud interaction viewpoint, which facilitates in reaching a closure of model simulated present day climate change and future climate projections. © 2017 Royal Meteorological Society."
"57217881153;57205189680;6602205640;10639674700;","Vegetation responses to late Holocene climate changes in an Andean forest",2018,"10.1017/qua.2017.64","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041671712&doi=10.1017%2fqua.2017.64&partnerID=40&md5=23e3023763b04f500ec190c372695c74","A paleoecological record from Lake Palotoa (1370 m elevation) in the Andean foothills of Peru spans the last 3800 years. Lake Palotoa lies near the modern cloud base in a location sensitive to changes in atmospheric moisture. In many areas, these forests have been destroyed, but Lake Palotoa shows no sign of human occupation today or in the past. The modern forest surrounding the lake is dominated by the Andean palm, Dictyocaryum lamarckianum, which is also the most abundant taxon in the fossil pollen record. Fossil pollen data show the vegetation assemblages have not experienced strong compositional changes in the late Holocene. Global-scale climatic events such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) are identified within the record, though the vegetation responses are subtle. Hedyosmum and Sloanea pollen percentages increase near the onset of the MCA and may reflect decreased seasonality. The LIA coincides with increased Hedyosmum pollen percentages, and increases in Clethra and Begonia, two elements that tend to occupy forests now found at higher elevations. Our findings demonstrate the stability of montane forest systems to natural Holocene climate change. Copyright © University of Washington. Published by Cambridge University Press, 2017."
"55023296500;26643193200;","The variation of cloud amount and light rainy days under heavy pollution over South China during 1960–2009",2018,"10.1007/s11356-017-0510-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033447353&doi=10.1007%2fs11356-017-0510-4&partnerID=40&md5=ddc3b2ae617b866e49fb3cc29619262b","The ground observation data was used to analyze the variation of cloud amount and light precipitation over South China during 1960–2009. The total cloud cover (TCC) decreases in this period, whereas the low cloud cover (LCC) shows the obvious opposite change with increasing trends. LCP defined as low cloud cover/total cloud cover has increased, and small rainy days (< 10 mm day−1) decreased significantly (passing 0.001 significance level) during the past 50 years, which is attributed to the enhanced levels of air pollution in the form of anthropogenic aerosols. The horizontal visibility and sunshine duration are used to depict the anthropogenic aerosol loading. When horizontal visibility declines to 20 km or sunshine duration decreases to 5 h per day, LCC increases 52% or more and LCP increases significantly. The correlation coefficients between LCC and horizontal visibility or sunshine duration are − 0.533 and − 0.927, and the values between LCP and horizontal visibility or sunshine duration are − 0.849 and − 0.641, which pass 0.001 significance level. The results indicated that aerosols likely impacted the long-term trend of cloud amount and light precipitation over South China. © 2017, The Author(s)."
"7004364155;6603546080;13204619900;8891521600;55804461200;55372257600;7202069518;8605057200;7102651635;56493740900;","Clouds and the Earth'S Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) top-of-atmosphere (TOA) edition-4.0 data product",2018,"10.1175/JCLI-D-17-0208.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040547128&doi=10.1175%2fJCLI-D-17-0208.1&partnerID=40&md5=12cc009a123440fa48334a1687d04b2c","The Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) top-of-atmosphere (TOA), Edition 4.0 (Ed4.0), data product is described. EBAF Ed4.0 is an update to EBAF Ed2.8, incorporating all of the Ed4.0 suite of CERES data product algorithm improvements and consistent input datasets throughout the record. A one-time adjustment to shortwave (SW) and longwave (LW) TOA fluxes is made to ensure that global mean net TOA flux for July 2005-June 2015 is consistent with the in situ value of 0.71 W m-2. While global mean all-sky TOA flux differences between Ed4.0 and Ed2.8 are within 0.5 W m-2, appreciable SW regional differences occur over marine stratocumulus and snow/sea ice regions. Marked regional differences in SW clear-sky TOA flux occur in polar regions and dust areas over ocean. Clear-sky LW TOA fluxes in EBAF Ed4.0 exceed Ed2.8 in regions of persistent high cloud cover. Owing to substantial differences in global mean clear-sky TOA fluxes, the net cloud radiative effect in EBAF Ed4.0 is -18 W m-2 compared to -21 W m-2 in EBAF Ed2.8. The overall uncertainty in 1° × 1° latitude-longitude regional monthly all-sky TOA flux is estimated to be 3 W m-2 [one standard deviation (1σ)] for the Terra-only period and 2.5 W m-2 for the Terra-Aqua period both for SW and LW fluxes. The SW clear-sky regional monthly flux uncertainty is estimated to be 6 W m-2 for the Terra-only period and 5 W m-2 for the Terra-Aqua period. The LW clear-sky regional monthly flux uncertainty is 5 W m-2 for Terra only and 4.5 W m-2 for Terra-Aqua. © 2018 American Meteorological Society."
"56114254900;7102863853;57203364777;","Late Quaternary TEX86 paleotemperatures from the world’s largest desert lake, Lake Turkana, Kenya",2018,"10.1007/s10933-016-9939-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009795036&doi=10.1007%2fs10933-016-9939-6&partnerID=40&md5=9eb05134f346c1a10c9412ec6952302a","Wetter climatic conditions prevailed across northern and Equatorial Africa during the terminal Pleistocene until the middle Holocene, a climate event known as the “African Humid Period” (AHP). Although hydrologic changes during this period are well-known, very few records of temperature are available for evaluating the mechanisms and dynamics of climate change during the AHP across tropical Africa. To quantify changes in temperature during the onset and termination of the AHP, the TEX86 temperature proxy was used to generate a 14,000 year record of the surface temperature of Lake Turkana. This biomarker and related measures have been used to reconstruct regional and high-latitude paleotemperatures from the oceans and other continental systems, including other large African lakes. Although Lake Turkana’s climate and hydrology are very different from other large African lakes, our reconstruction exhibits a temperature history that shares a number of climatic trends with previous reconstructions. The TEX86 temperatures from Lake Turkana from 14 to 0.4 ka range from 24.3 to 28.6 °C, with a gradual decrease in temperature from early to late Holocene. This cooling roughly follows northern hemisphere summer insolation, similar to the trend observed in Lake Victoria and other regional records. However, the record from Turkana contains many abrupt temperature shifts not seen in other large lakes in the region. Multi-century-scale fluctuations persist through most of the record, and can be attributed to periods of lake mixing. Larger temperature perturbations are likely associated with changes in evaporation and cloud cover. © 2017, Springer Science+Business Media Dordrecht."
"57033058300;12240469400;15840948500;56145346300;24597637700;57157925000;56625399700;57212421118;55900043700;","Improving MODIS snow products with a HMRF-based spatio-temporal modeling technique in the Upper Rio Grande Basin",2018,"10.1016/j.rse.2017.10.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031415414&doi=10.1016%2fj.rse.2017.10.001&partnerID=40&md5=12db3a75005ae4a6f051d31c1533276d","Seasonal snow cover and its melt dominate regional climate and hydrology in many mountainous regions in the world. The Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products have been widely used for regional hydrological modeling. However, data gaps in snow products due to frequent clouds remain a serious problem, particularly for daily products. This paper presents a spatio-temporal modeling technique for filling up data gaps in daily snow cover estimates, based on time series of Terra/Aqua MODIS images. The spatio-temporal modeling technique integrates MODIS spectral information, spatial and temporal contextual information, and environmental association within a Hidden Markov Random Field (HMRF) framework. The performance of our new technique is quantitatively evaluated by comparing our snow cover estimates with in situ observations at 33 SNOTEL stations as well as to original MODIS snow cover products over the Upper Rio Grande Basin during 2006–2008 snow seasons. Mainly due to cloud obscuration, there are as high as 32% data gaps in original Terra/Aqua combined MODIS snow products. Our HMRF technique reduced cloud-cover related data gaps to < 1% and achieved a snow-mapping accuracy of 88.0% for the gap-filled areas. For the areas not covered by clouds, our HMRF-based technique also improved the snow cover estimate accuracy of original MODIS snow products by 3.5%, from 85.1% to 88.6%. When spatio-temporal contextual information and environmental association information are progressively incorporated within the HMRF framework, the overall snow mapping accuracies are improved and omission errors are reduced. Particularly, our HMRF-based technique increased the snow product accuracy by 4.2% during whole transition periods, and by 6.2% in March during snow melt. The snow mapping accuracies were significantly improved over evergreen forests and mixed forests. © 2017 Elsevier Inc."
"55910358700;7004325649;56744278700;7103086179;57206503877;35425197200;57203078473;9274531600;35514012200;7403925891;56880164500;7402645443;6602621807;14023953700;37099944400;7006212411;57200313964;7102592460;7402146514;7004364155;7005939834;7003543851;16029394900;7202899330;35516489800;57192810488;7005578774;7006630889;","Designing the Climate Observing System of the Future",2018,"10.1002/2017EF000627","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040778037&doi=10.1002%2f2017EF000627&partnerID=40&md5=95e0042d583b84387e0fa2203a44937d","Climate observations are needed to address a large range of important societal issues including sea level rise, droughts, floods, extreme heat events, food security, and freshwater availability in the coming decades. Past, targeted investments in specific climate questions have resulted in tremendous improvements in issues important to human health, security, and infrastructure. However, the current climate observing system was not planned in a comprehensive, focused manner required to adequately address the full range of climate needs. A potential approach to planning the observing system of the future is presented in this article. First, this article proposes that priority be given to the most critical needs as identified within the World Climate Research Program as Grand Challenges. These currently include seven important topics: melting ice and global consequences; clouds, circulation and climate sensitivity; carbon feedbacks in the climate system; understanding and predicting weather and climate extremes; water for the food baskets of the world; regional sea-level change and coastal impacts; and near-term climate prediction. For each Grand Challenge, observations are needed for long-term monitoring, process studies and forecasting capabilities. Second, objective evaluations of proposed observing systems, including satellites, ground-based and in situ observations as well as potentially new, unidentified observational approaches, can quantify the ability to address these climate priorities. And third, investments in effective climate observations will be economically important as they will offer a magnified return on investment that justifies a far greater development of observations to serve society's needs. © 2017 The Authors."
"57196436529;6603667298;54790046100;36810645500;7101689290;7202571007;","A 42 year inference of cloud base height trends in the Luquillo Mountains of northeastern Puerto Rico",2018,"10.3354/cr01529","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053248722&doi=10.3354%2fcr01529&partnerID=40&md5=c9a23c87b52d8ca3c612efa5757ea621","The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainforest managed by the United States Forest Service, with cloud-immersed forests historically occupying the highest elevations. However, within the past 50 yr, studies of the Luquillo cloud forest have suggested an increase in cloud base heights (CBH), although the CBH in the area was not quantified until recently. The present work uses radiosonde observations from nearby San Juan, Puerto Rico, to contextualize the present-day CBH within a 42 yr (1975-2016) proxy record and determine evidence for rising cloud base. Two key questions are addressed: (1) Can theoretical CBH calculations from San Juan provide a reasonable proxy for CBHs in the Luquillo Mountains? (2) Does a significant trend accompany the CBH lifting inferred from recent work in the region? The mean-layer lifted condensation level (MLLCL), a thermodynamic parameter expressing the altitude at which a rising air parcel reaches 100% relative humidity, serves as the proxy. The 42 yr MLLCL time series corroborates both the low CBHs claimed in the 1980s and the higher CBHs documented by recent work. When considering all available radiosonde data, statistically significant increasing CBH trends are detected for all seasons. However, when the record is standardized to correct for progressive vertical resolution improvements to radiosonde observations, recent CBH increases are more modest than initially indicated, and statistically significant increases are only apparent in the late rainfall season. © Inter-Research 2018."
"56610305200;7005337548;","Why is the ocean surface slightly warmer than the atmosphere?",2018,"10.1357/002224018824082007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057836167&doi=10.1357%2f002224018824082007&partnerID=40&md5=0d2e508096dfee5c6a6815bb3f05ca0a","How much warmer is the ocean surface than the atmosphere directly above it? The present study offers a means to quantify this temperature difference using a conceptual nonlinear one-dimensional global energy balance coupled ocean–atmosphere model (“Aqua Planet”). The significance of our idealized model, which is of intermediate complexity, is its ability to obtain an analytical solution for the global average temperatures. Our analytical model results show that, for the present climate, predicted global mean ocean temperature is 291.1 K whereas surface atmospheric temperature above the ocean surface is 287.4 K. Thus, the modeled surface ocean is 3.7 K warmer than the atmosphere above it. Temporal perturbation of the global mean solution obtained for “Aqua Planet” showed a stable system. Oscillation amplitude of the atmospheric temperature anomaly is greater in magnitude than those found in the ocean. There is a phase shift (a lag in the ocean), which is caused by oceanic thermal inertia. Climate feedbacks due to selected climate parameters such as incoming radiation, cloud cover, and CO2 are discussed. Warming obtained with our model compares well with Intergovernmental Panel on Climate Change’s (IPCC) estimations. Application of our model to local regions illuminates the importance of evaporative cooling in determining derived air–sea temperature offsets, where an increase in the latter increases the systems overall sensitivity to evaporative cooling. © 2018 Lakshika Girihagama and Doron Nof."
"57200048845;6602829165;55663720200;","Detection and attribution of climate change signals in South India maximum and minimum temperatures",2018,"10.3354/cr01530","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054864053&doi=10.3354%2fcr01530&partnerID=40&md5=3ea046e5457184f326071f7035c78679","South India has seen significant changes in climate. Previous studies have shown that the southern part of India is more susceptible to effects of climate change than the rest of the country. We performed a rigorous climate model-based detection and attribution analysis to determine the root cause of the recent changes in climate over South India using fingerprint analysis. A modified Mann-Kendall test signalized non-stationariness in maximum and minimum temperatures (Tmax and Tmin) in most seasons during the period 1950-2012. The diminishing cloud cover trend may have induced significant changes in temperature during the considered time period. Significant downward trends in relative humidity during most seasons could be evidence of the recent significant warming. The observed seasonal Tmax and Tmin change patterns are strongly associated with the El Ninõ Southern Oscillation. Significant positive associations between South India temperatures and the Ninõ3.4 index were found in all seasons. The fingerprint approach indicated that the natural internal variability obtained from 14 climate model control simulations could not explain these significant changes in Tmax (post-monsoon) and Tmin (pre-monsoon and monsoon) in South India. Moreover, an experiment simulating natural external forcings (solar and volcanic) did not coincide with the observed signal strength. The dominant external factors leading to climate change are greenhouse gases, and their impact is eminent compared to other factors such as land use change and anthropogenic aerosols. Anthropogenic signals are identifiable in observed changes in Tmax and Tmin of South India, and these changes can be explained only when anthropogenic forcing is involved. © 2018 Inter-Research."
"56494358600;55684857500;56629149600;57200364069;12794136800;57205604469;6603713560;39863793300;56511954300;57200366382;57200364998;","ENSO influence on coastal fog-water yield in the atacama desert, Chile",2018,"10.4209/aaqr.2017.01.0022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040984004&doi=10.4209%2faaqr.2017.01.0022&partnerID=40&md5=a4c4658ae44b0b7d1106310789acbb05","Fog water represents an alternative, abundant and currently unexploited fresh water resource in the coastal Atacama Desert (~20°S). Here, the stratocumulus clouds meet the Coastal Cordillera, producing highly dynamic advective marine fog, a major feature of the local climate that provides water to a hyper-arid environment. One of the main issues that arises in harvesting fog water is our limited understanding of the spatial and inter-annual variability of fog clouds and their associated water content. Here we assess the role of regional-wide El Niño Southern Oscillation (ENSO) forcing on local inter-annual fog-water yields along the coast of Atacama. We contrast 17 years of continuous fog-water data, with local and regional atmospheric and oceanographic variables to determine the link between them and the inter-annual dynamics of fog in northern Chile. Sea surface temperature (SST) in ENSO zone 1 + 2 shows significant correlations with offshore and coastal Atacama SST, as well as with local low cloud cover and fog water yields, which go beyond the annual cycle beat, exposing a potential causal link and influence of ENSO on fog along the Atacama. On the inter-annual time scale, we found that when ENSO 3 + 4 zone SST, specifically during summer, overcome a > 1°C temperature threshold, they incite significantly higher summer fog water yields and explain 79% of the fog variability. Furthermore, satellite images displaying regional extent Sc cloud and fog presence during ENSO extremes reveal higher cloud abundance during El Niño at this latitude. However, 75% of the yearly fog water is collected during winter, and does not appear to be affected in a significant manner by Pacific oscillations. Thus, our results suggest that the utilization of fog as a fresh water resource may be sustainable in the future, regardless of ENSO-induced variability in the region. © Taiwan Association for Aerosol Research."
"9244992800;57200279456;57192273006;","Widening of the Hadley Cell from Last Glacial Maximum to future climate",2018,"10.1175/JCLI-D-17-0328.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040572273&doi=10.1175%2fJCLI-D-17-0328.1&partnerID=40&md5=e52c924ada86b7ff02f3e255789df7e0","The Hadley cell (HC) change from paleoclimate to future climate is examined by comparing coupled model simulations archived for the Paleoclimate Modeling Intercomparison Project phase 3 (PMIP3) and phase 5 of the Coupled Model Intercomparison Project (CMIP5). Specifically, HC width and strength are evaluated using 100-yr equilibrium simulations for the Last Glacial Maximum (LGM), preindustrial (PI), and extended concentration pathway 4.5 (ECP4.5) conditions. Where available, ECP8.5 simulations are also examined to increase the sample size. All models show a systematic widening of the HC from the LGM to the PI and to the ECP4.5 and ECP8.5 simulations. Such widening, which is found in both hemispheres with more robust change in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), is significantly correlated with global-mean surface air temperature change and the associated static stability change in the subtropics. Based on the zero-crossing latitude of 500-hPa mass streamfunction, about 4.5° latitude widening of the HC results from global warming of 10°C. HC strength also exhibits a systematic weakening in the NH. However, in the SH, HC strength shows a rather minor change from LGM to ECP4.5 conditions because of the cancellation between HC weakening during the austral summer-fall and its strengthening during the spring. This result, which suggests no systematic relationship between HC width and strength changes, is discussed in the context of quasigeostrophic zonal-mean dynamics. Overall findings are also compared with recent studies that are based on transient climate model simulations. © 2018 American Meteorological Society."
"57193156689;24586870400;36917387900;36184294300;55938857300;","Evaluation of the Regional Climate Model over the Loess Plateau of China",2018,"10.1002/joc.5159","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021332317&doi=10.1002%2fjoc.5159&partnerID=40&md5=bf66b670366e1c96a846817b70399d69","This paper presents an evaluation study of the Regional Climate Model version 4.3 (RegCM4.3) over the Loess Plateau in northern China, which is a semi-arid region characterized by complex topography. During recent years, a series of reforestation programmes have been implemented across the region that might influence the local climate in complex ways. To better understand the local climate, the RegCM4.3 was applied to simulate the present-day conditions over the Loess Plateau. The simulation was carried out from 1990 to 2009 at the 50-km horizontal resolution, with lateral boundary conditions taken from the ECMWF-Interim reanalysis. A series of climate variables and processes were evaluated during the winter and summer seasons, such as 2-m air temperature, precipitation, wind circulation, surface energy balance, full moisture budget, and cloud radiative forcing (CRF). The possible origins of the simulation bias and the physical linkages with other model processes were examined. In general, RegCM4.3 is able to reproduce both the spatial and temporal features of the regional climate over the Loess Plateau. However, there are still biases in some meteorological variables including precipitation and 2-m air temperature. In particular, the model tends to produce cold biases during winter and underestimate precipitation during summer. Further analyses indicates that the cold biases in winter may have resulted from the deficiency of the downward longwave radiation fluxes, excessive ground heat fluxes, and negative temperature advection by the seasonal mean circulation. These processes are primarily triggered by deficiencies in CRF and excessive northwesterlies over the plateau. The underestimated precipitation during summer is associated with a weak southerly monsoon in the model. A full moisture budget analysis reveals that the dry bias in this region can be mainly attributed to model deficiency in moisture advection and convergence, and to a lesser extent to that in surface evaporation. © 2017 Royal Meteorological Society"
"57193882808;","Can the impact of aerosols on deep convection be isolated from meteorological effects in atmospheric observations?",2018,"10.1175/JAS-D-18-0105.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057380269&doi=10.1175%2fJAS-D-18-0105.1&partnerID=40&md5=ebf4276758d8fca48b240333ca0bc774","Influence of pollution on dynamics of deep convection continues to be a controversial topic. Arguably, only carefully designed numerical simulations can clearly separate the impact of aerosols from the effects of meteorological factors that affect moist convection. This paper argues that such a separation is virtually impossible using observations because of the insufficient accuracy of atmospheric measurements and the fundamental nature of the interaction between deep convection and its environment. To support this conjecture, results from numerical simulations are presented that apply modeling methodology previously developed by the author. The simulations consider small modifications, difficult to detect in observations, of the initial sounding, surface fluxes, and large-scale forcing tendencies. All these represent variations of meteorological conditions that affect deep convective dynamics independently of aerosols. The setup follows the case of daytime convective development over land based on observations during the Large-Scale Biosphere- Atmosphere (LBA) field project in Amazonia. The simulated observable macroscopic changes of convection, such as the surface precipitation and upper-tropospheric cloudiness, are similar to or larger than those resulting from changes of cloud condensation nuclei from pristine to polluted conditions studied previously using the same modeling case. Observations from Phase III of the Global Atmospheric Research Program Atlantic Tropical Experiment (GATE) are also used to support the argument concerning the impact of the large-scale forcing. The simulations suggest that the aerosol impacts on dynamics of deep convection cannot be isolated from meteorological effects, at least for the daytime development of unorganized deep convection considered in this study. © 2018 American Meteorological Society."
"36193302500;56013882400;14030547700;","Tree-ring research of mexican beech (fagus grandifolia subsp. Mexicana) a relict tree endemic to Eastern Mexico",2018,"10.3959/1536-1098-74.1.94","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042521839&doi=10.3959%2f1536-1098-74.1.94&partnerID=40&md5=a979fb631befbf9676785e1ee19d6b61","Mexican beech (Fagus grandifolia subsp. Mexicana) has been classified as an endangered species because of its restricted distribution. The current distribution of Mexican beech, which is considered a Miocene relict, is limited to Tropical Montane Cloud Forests (TMCF) in the mountains of the Sierra Madre Oriental in eastern Mexico. We used dendroclimatic techniques to evaluate the effects of climate variability on the growth of Mexican beech within three forest fragments. The independent chronologies developed for the three sites were 152-178 years long. Cross-sections helped to assess the quality of the crossdating and detect false rings. Over the last 180 years, Mexican beech trees have lower mean radial growth than rates exhibited by other Fagus species. Mexican beech growth appears to be influenced by growing-season temperatures, especially mean maximum temperature. The response appears to be positive at the beginning of the growing season but becomes negative later. These results suggest that the persistence of Fagus-dominated forests in Mexico is dependent on local-scale climatic conditions of the TMCF. Mexican beech forests are associated with micro-climatic conditions that will control the fate of these forests in the face of on-going climate change. © Copyright 2018 by The Tree-Ring Society."
"57192264902;7404552200;57195074310;56177421400;7005262634;55681862500;","Determining the start of the growing season from MODIS data in the Indian Monsoon Region: Identifying available data in the rainy season and modeling the varied vegetation growth trajectories",2018,"10.3390/rs10010122","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040680999&doi=10.3390%2frs10010122&partnerID=40&md5=2ece90f52ed49c0e3d2490c991396dcd","In the Indian monsoon region, frequent cloud cover in the rainy season results in less valid satellite observations during the vegetation growth period, making it difficult to extract land surface phenology (LSP). Even worse, many valid but humid observations were misidentified as clouds in the MODIS cloud mask, causing severe gaps in the LSP product. Using a refined cloud detection approach to separate clear-sky and cloudy observations, this study found that potentially valid observations during the vegetation growth period could be identified. Furthermore, the varied vegetation growth trajectories cannot be well-fitted by a global curve-fitting approach, but can be modelled by using the locally adjusted cubic-spline capping approach, which performed well for any seasonal patterns. Applying this approach, the start of growing season (SOS) was determined with 9.18% of vegetation growth amplitude between the maximum and minimum NDVI to generate the SOS product (2000-2016). The valid percentage of this regional product largely increased from 29.30% to 69.76% compared with the MCD12Q2 product, and its reliability was approximate to that of deciduous broadleaf forest in North America and Europe. This product could serve as a basis for understanding the response of terrestrial ecosystems to the changing Indian monsoon."
"49061377100;55881697700;7004114606;55907266900;6603155100;24344797600;","Landscape-scale drivers of glacial ecosystem change in the montane forests of the eastern Andean flank, Ecuador",2018,"10.1016/j.palaeo.2017.10.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031818100&doi=10.1016%2fj.palaeo.2017.10.011&partnerID=40&md5=9ffb291d5310e9a4b180efb417a4d4b6","Understanding the impact of landscape-scale disturbance events during the last glacial period is vital in accurately reconstructing the ecosystem dynamics of montane environments. Here, a sedimentary succession from the tropical montane cloud forest of the eastern Andean flank of Ecuador provides evidence of the role of non-climate drivers of vegetation change (volcanic events, fire regime and herbivory) during the late-Pleistocene. Multiproxy analysis (pollen, non-pollen palynomorphs, charcoal, geochemistry and carbon content) of the sediments, radiocarbon dated to ca. 45–42 ka, provide a snap shot of the depositional environment, vegetation community and non-climate drivers of ecosystem dynamics. The geomorphology of the Vinillos study area, along with the organic‑carbon content, and aquatic remains suggest deposition took place near a valley floor in a swamp or shallow water environment. The pollen assemblage initially composed primarily of herbaceous types (Poaceae-Asteraceae-Solanaceae) is replaced by assemblages characterised by Andean forest taxa, (first Melastomataceae-Weinmannia-Ilex, and later, Alnus-Hedyosmum-Myrica). The pollen assemblages have no modern analogues in the tropical montane cloud forest of Ecuador. High micro-charcoal and rare macro-charcoal abundances co-occur with volcanic tephra deposits suggesting transportation from extra-local regions and that volcanic eruptions were an important source of ignition in the wider glacial landscape. The presence of the coprophilous fungi Sporormiella reveals the occurrence of herbivores in the glacial montane forest landscape. Pollen analysis indicates a stable regional vegetation community, with changes in vegetation population co-varying with large volcanic tephra deposits suggesting that the structure of glacial vegetation at Vinillos was driven by volcanic activity. © 2017 The Authors"
"56082274200;7201858269;","Elevated temperatures are associated with stress in rooftop-nesting Common Nighthawk (Chordeiles minor) chicks",2018,"10.1093/conphys/coy010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052784066&doi=10.1093%2fconphys%2fcoy010&partnerID=40&md5=779c7d1dcab66db9164346f8f73f5584","Grasslands and riparian forests in southeastern South Dakota have been greatly reduced since historical times, primarily due to conversion to row-crop agriculture. Common Nighthawk (Chordeiles minor) nesting habitat includes grasslands, open woodlands and urban rooftops, but nesting sites in southeastern South Dakota are confined to rooftops, as natural nesting habitat is limited. Nighthawks nesting on exposed rooftop habitats may encounter thermal conditions that increase operative temperatures relative to vegetated land cover types. Mean humidity has increased and mean wind speed and cloud cover have decreased during the nighthawk breeding season from 1948 to 2016 in southeastern South Dakota. These changes might contribute to increasing operative temperatures at exposed rooftop nest sites and this could influence chick condition. We studied nest micro-climate and the plasma stress response for 24 rooftop-nesting nighthawk chicks from 17 nests during 2015 and 2016. High humidity prior to blood collection reduced both baseline and stress-induced plasma corticosterone (CORT). In contrast, high maximum temperatures during the day before sampling increased stress-induced CORT. The magnitude of the chick stress response was significantly negatively related to maximum wind speed for the week prior to CORT measurement. Other weather and micro-climate variables were not significant effectors of CORT metrics. Most chicks had low baseline CORT and were able to mount a stress response, but a subset of chicks (n = 4) showed elevated baseline CORT and a negative association between the magnitude of stress response and ambient temperature. For this subset, mean ambient temperature for the day before sampling was significantly higher (2.3°C) than for chicks with typical baseline CORT levels. These data suggest that regional climate change trends could affect the ability of nighthawk chicks to mount a stress response, which, in turn, might influence the susceptibility of nighthawk chicks to climate change in the Northern Prairie region. © The Author(s) 2018."
"56531117000;57217623485;9734637500;","Combined influence of multiple climatic factors on the incidence of bacterial foodborne diseases",2018,"10.1016/j.scitotenv.2017.08.045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026907389&doi=10.1016%2fj.scitotenv.2017.08.045&partnerID=40&md5=9c459daf31f13fab83ae539863bbad85","Information regarding the relationship between the incidence of foodborne diseases (FBD) and climatic factors is useful in designing preventive strategies for FBD based on anticipated future climate change. To better predict the effect of climate change on foodborne pathogens, the present study investigated the combined influence of multiple climatic factors on bacterial FBD incidence in South Korea. During 2011–2015, the relationships between 8 climatic factors and the incidences of 13 bacterial FBD, were determined based on inpatient stays, on a monthly basis using the Pearson correlation analyses, multicollinearity tests, principal component analysis (PCA), and the seasonal autoregressive integrated moving average (SARIMA) modeling. Of the 8 climatic variables, the combination of temperature, relative humidity, precipitation, insolation, and cloudiness was significantly associated with salmonellosis (P < 0.01), vibriosis (P < 0.05), and enterohemorrhagic Escherichia coli O157:H7 infection (P < 0.01). The combined effects of snowfall, wind speed, duration of sunshine, and cloudiness were not significant for these 3 FBD. Other FBD, including campylobacteriosis, were not significantly associated with any combination of climatic factors. These findings indicate that the relationships between multiple climatic factors and bacterial FBD incidence can be valuable for the development of prediction models for future patterns of diseases in response to changes in climate. © 2017 Elsevier B.V."
"57200702127;7404829395;56537463000;12040335900;55814053500;8953662800;7005973015;","Elucidating the role of anthropogenic aerosols in Arctic sea ice variations",2018,"10.1175/JCLI-D-17-0287.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040538052&doi=10.1175%2fJCLI-D-17-0287.1&partnerID=40&md5=ccf04daf42547a690e767a2347c85767","Observations show that the Arctic sea ice cover has been shrinking at an unprecedented rate since the 1970s. Even though the accumulation of greenhouse gases in the atmosphere has been closely linked with the loss of Arctic sea ice, the role of atmospheric aerosols in past and future Arctic climate change remains elusive. Using a state-of-the-art fully coupled climate model, the authors assess the equilibrium responses of the Arctic sea ice to the different aerosol emission scenarios and investigate the pathways by which aerosols impose their influence in the Arctic. These sensitivity experiments show that the impacts of aerosol perturbations on the pace of sea ice melt effectively modulate the ocean circulation and atmospheric feedbacks. Because of the contrasting evolutions of particulate pollution in the developed and developing countries since the 1970s, the opposite aerosol forcings from different midlatitude regions are nearly canceled out in the Arctic during the boreal summer, resulting in a muted aerosol effect on the recent sea ice changes. Consequently, the greenhouse forcing alone can largely explain the observed Arctic sea ice loss up to the present. In the next few decades, the projected alleviation of particulate pollution in the Northern Hemisphere can contribute up to 20% of the total Arctic sea ice loss and 0.7°C surface warming over the Arctic. The authors' model simulations further show that aerosol microphysical effects on the Arctic clouds are the major component in the total aerosol radiative forcing over the Arctic. Compared to the aerosol-induced energy imbalance in lower latitudes outside the Arctic, the local radiative forcing by aerosol variations within the Arctic, due to either local emissions or long-range transports, is more efficient in determining the sea ice changes and Arctic climate change. © 2018 American Meteorological Society."
"7006083502;7003390361;7004479957;57200540848;7003495982;7003686819;7005865667;23019327900;55666105200;7005342702;8689674700;7003875148;7202502647;","100 years of progress in boundary layer meteorology",2018,"10.1175/AMSMONOGRAPHS-D-18-0013.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076136671&doi=10.1175%2fAMSMONOGRAPHS-D-18-0013.1&partnerID=40&md5=a724c0430d59c6a3e6d54aab797ed348","Over the last 100 years, boundary layer meteorology grew from the subject of mostly near-surface observations to a field encompassing diverse atmospheric boundary layers (ABLs) around the world. From the start, researchers drew from an ever-expanding set of disciplines—thermodynamics, soil and plant studies, fluid dynamics and tur-bulence, cloud microphysics, and aerosol studies. Research expanded upward to include the entire ABL in response to the need to know how particles and trace gases dispersed, and later how to represent the ABL in numerical models of weather and climate (starting in the 1970s–80s); taking advantage of the opportunities afforded by the development of large-eddy simulations (1970s), direct numerical simulations (1990s), and a host of instruments to sample the boundary layer in situ and remotely from the surface, the air, and space. Near-surface flux-profile relationships were developed rapidly between the 1940s and 1970s, when rapid progress shifted to the fair-weather convective boundary layer (CBL), though tropical CBL studies date back to the 1940s. In the 1980s, ABL research began to include the interaction of the ABL with the surface and clouds, the first ABL parameterization schemes emerged; and land surface and ocean surface model development blossomed. Research in subsequent decades has focused on more complex ABLs, often identified by shortcomings or uncertainties in weather and climate models, including the stable boundary layer, the Arctic boundary layer, cloudy boundary layers, and ABLs over heterogeneous surfaces (in-cluding cities). The paper closes with a brief summary, some lessons learned, and a look to the future. © 2019 American Meteorological Society."
"55613105600;36011357900;6701915334;6701610266;6701832491;","Evaluation of 20CR reanalysis data and model results based on historical (1930-1940) observations from Franz Josef Land",2018,"10.24425/118747","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049231779&doi=10.24425%2f118747&partnerID=40&md5=2dda6b04453730abcb73538b7f5bb253","Unique and independent historical observations, carried out in the central Arctic during the early twentieth century warming (ETCW) period, were used to evaluate the older (20CRv2) and newer (20CRv2c) versions of the 20th Century Reanalysis and the HIRHAM5 regional climate model. The latter can reduce several biases compared to its forcing data set (20CRv2) probably due to higher horizontal resolution and a more realistic cloud parameterization. However, low-level temperature and near-surface specific humidity agree best between 20CRv2c and the surface-based observations. This better performance results from more realistic lower boundary conditions for sea ice concentration and sea surface temperature, but it is limited mainly to polar night. Although sea level pressures are very similar, the vertical stratification and baroclinicity change in the transition from 20CRv2 to 20CRv2c. Compared to observed temperature profiles, the systematic cold bias above 400 hPa remains almost unchanged indicating an incorrect coupling between the planetary boundary layer and free troposphere. In addition to surface pressures, it is therefore recommended to assimilate available vertical profiles of temperature, humidity and wind speed. This might also reduce the large biases in 10 m wind speed, but the reliability of the sea ice data remains a great unknown. © Polish Academy of Sciences. All rights reserved."
"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 (Dp) ranges: >ĝ€̄3ĝ€̄nm, >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."
"55220137100;57188671338;35241136800;55579449500;7202412306;7003271017;57200368817;","Fog spatial distributions over the central namib desert - An isotope approach",2018,"10.4209/aaqr.2017.01.0062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040993944&doi=10.4209%2faaqr.2017.01.0062&partnerID=40&md5=b865cdd162dffe21d07198461b24dbc5","Fog is a characteristic feature of the Namib Desert and is essential to life in this fog dependent system. It is often acknowledged that advective fog from the ocean is the dominant fog type over the Namib Desert fog-zone but recent evidence suggests that other fog types occur in this area. Knowledge of the existence and spatial distribution of different fog types will enhance the mechanistic understanding of fog formation and potential changes in this region, but such knowledge is limited in literature. In this study, we investigated fog spatial variations within the Namib Desert fog-zone by applying stable isotope (δ18O and δ2H) techniques to differentiate various fog types and identify their source waters. Isotope based results showed that at least three types of fog (advective, radiation and mixed) occurred in this region and what appears as a single fog event may include all three types. Results suggest that radiation fog was the dominant fog type during our study period. The results also suggest that advective fog (with Atlantic Ocean origins) either dissipated 30–50 km inland and the residual humidity combined with locally derived moisture to form mixed fog or advective fog incorporated local moisture along its trajectory inland resulting in mixed fog. Fog in the Namib Desert was consistently depleted in 18O and2H compared to rainfall and this was attributed to sub-cloud evaporation of the rainfall as well as different sources of fog and rainfall. Sub-cloud evaporation led to enrichment of 18O and2H in rainfall beyond that of the first stage condensate, fog. Advective fog is often considered the architect of the fog-zone in the Namib Desert, but our results demonstrated multiple dominant fog types during the study period, suggesting knowledge of both fog frequency and fog type is needed to better predict climate change impacts on the fog-zone. © Taiwan Association for Aerosol Research."
"9844340200;7004496626;57208846598;57209873895;","Light availability and phytoplankton growth beneath arctic sea ice: Integrating observations and modeling",2018,"10.1029/2017JC013617","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062628376&doi=10.1029%2f2017JC013617&partnerID=40&md5=c4d935d177ebf558dbe5d4c05a1ff5fc","Observations of the seasonal light field in the upper Arctic Ocean are critical to understanding the impacts of changing Arctic ice conditions on phytoplankton growth in the water column. Here we discuss data from a new sensor system, deployed in seasonal ice cover north-east of Utqiaġvik, Alaska in March 2014. The system was designed to provide observations of light and phytoplankton biomass in the water column during the formation of surface melt ponds and the transition from ice to open water. Hourly observations of downwelling irradiance beneath the ice (at 2.9, 6.9, and 17.9 m depths) and phytoplankton biomass (at 2.9 m depth) were transmitted via Iridium satellite from 9 March to 10 November 2014. Evidence of an under-ice phytoplankton bloom (Chl a ~8 mgm -3 ) was seen in June and July. Increases in light intensity observed by the buoy likely resulted from the loss of snow cover and development of surface melt ponds. A bio-optical model of phytoplankton production supported this probable trigger for the rapid onset of under-ice phytoplankton growth. Once under-ice light was no longer a limiting factor for photosynthesis, open water exposure almost marginally increased daily phytoplankton production compared to populations that remained under the adjacent ice. As strong effects of climate change continue to be documented in the Arctic, the insight derived from autonomous buoys will play an increasing role in understanding the dynamics of primary productivity where ice and cloud cover limit the utility of ocean color satellite observations. © 2018. American Geophysical Union."
"8212745300;6603031730;","Reconstruction of Landsat time series in the presence of irregular and sparse observations: Development and assessment in north-eastern Alberta, Canada",2018,"10.1016/j.rse.2017.07.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030768549&doi=10.1016%2fj.rse.2017.07.036&partnerID=40&md5=82813b57b5fa87857c2e5b2bc5a16d21","Time series analysis of Landsat is limited by sparse and irregular sampling of clear-sky observations due to acquisition limitations, clouds, shadows, atmosphere, and sensor artifacts. Many remote sensing applications utilizing coarse spatial resolution time series methods are not suitable for Landsat due to observation sparsity. In this research we develop an imputation based approach to constrain the harmonic modeling method of Zhu et al. (2012, 2015) and Zhu and Woodcock (2014b) to reconstruct Landsat time series at a regular temporal interval. The approach was assessed for a boreal forest region in central Canada for different sparsity conditions. The imputed Landsat estimates for a specific pixel were predicted from climate or AVHRR data. These estimates were given a small weight relative to available Landsat observations in fitting the final harmonic model essentially constraining it to a more plausible range. In addition we implemented the model in a piecewise manner to handle non-linear temporal drift related to factors such as climate change, drought, or the allometric nature of vegetation regrowth. Results show that the inclusion of imputed estimates improved model predictions in the presence of observation sparsity. Where there were less than 3 observations within ± 20 days the imputation approach performed better, with a reduction in average reflectance error of 0.001 to 2.5. Error assessment with hold out observations, comparison to MODIS time series, and example predicted images are presented. © 2017"
"36448166800;56000933900;","New records of a critically endangered shrew from Mexican cloud forests (Soricidae, Cryptotis nelsoni) and prospects for future field research",2018,"10.3897/BDJ.6.e26667","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057444562&doi=10.3897%2fBDJ.6.e26667&partnerID=40&md5=6c2591509117c04c19cdf0a5b3991363","The Nelson's small-eared shrew, Cryptotis nelsoni (Merriam, 1895), is a critically endangered species, endemic to cloud forests in Los Tuxtlas, a mountain range along the Gulf of Mexico coast. This species is only known from the type locality and its surroundings. Here we present new records that extend its distribution approximately 7 km southeast of the type locality and report more specimens near to the type locality. We also identified climatically suitable areas for C. nelsoni using ecological niche modelling and investigated the sampling bias to identify poorly sampled areas in Los Tuxtlas. We suggest that the scarcity of records in other areas with suitable climatic conditions throughout Los Tuxtlas is a consequence of incomplete surveys. We strongly highlight the importance of continuing surveying this critically endangered shrew using more efficient sampling techniques to better understand its current distribution and conservation status. Despite all known localities occurring inside Los Tuxtlas Biosphere Reserve, deforestation and climate change still pose current and future threats to this species. © Guevara L, Sánchez-Cordero V."
"57200655043;25634057900;57200655329;56210861200;","The performance rainfall during rainy seasonal over Thailand by using preliminary regional coupled atmospheric and oceanic (wrf-roms) model",2018,"10.21660/2018.45.7326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042119774&doi=10.21660%2f2018.45.7326&partnerID=40&md5=f3e821062dcff6e6ecc5886f84975168","A coupled regional climate between atmosphere-ocean coupled model systems is developed using the regional model Weather Research and Forecasting (WRF) and Regional Ocean Modeling System (ROMS) to simulate performance rainfall during the rainy season over Thailand. The processes of the atmospheric model are provided to the ocean model. The wind (Uwind, Vwind), the atmospheric pressure (Patm), the relative humidity (RH), the atmosphere surface temperature (Tair), the cloud fraction (Cloud), precipitation (Rain), the short wave (SW), the long wave (LW). The processes of the oceanic model provide sea surface temperature (SST) to atmosphere model. The simulation period is during June-July-August (JJA) in 2014, and the results are compared with rainfall gauge station from Thai Metrology Department (TMD). The results show a good trend performance rainfall and can capture large amount rainfall in June, July and JJA 2014. The average rainfall and Mean Absolute Error (MAE) showed good value in June, July and JJA 2014, especially in June was shown good value average (236.25 mm) and MAE (4.389) than other months. © Int. J. of GEOMATE."
"7401800593;57214786060;57191294058;","On the dust load and rainfall relationship in South Asia: an analysis from CMIP5",2018,"10.1007/s00382-017-3617-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015188037&doi=10.1007%2fs00382-017-3617-x&partnerID=40&md5=a558f3b6d4895e150e46881f25b0fbd2","This study is aimed at examining the consistency of the relationship between load of dust and rainfall simulated by different climate models and its implication for the Indian summer monsoon system. Monthly mean outputs of 12 climate models, obtained from the archive of the Coupled Model Intercomparison Project phase 5 (CMIP5) for the period 1951–2004, are analyzed to investigate the relationship between dust and rainfall. Comparative analysis of the model simulated precipitation with the India Meteorological Department (IMD) gridded rainfall, CRU TS3.21 and GPCP version 2.2 data sets show significant differences between the spatial patterns of JJAS rainfall as well as annual cycle of rainfall simulated by various models and observations. Similarly, significant inter-model differences are also noted in the simulation of load of dust, nevertheless it is further noted that most of the CMIP5 models are able to capture the major dust sources across the study region. Although the scatter plot analysis and the lead–lag pattern correlation between the dust load and the rainfall show strong relationship between the dust load over distant sources and the rainfall in the South Asian region in individual models, the temporal scale of this association indicates large differences amongst the models. Our results caution that it would be pre-mature to draw any robust conclusions on the time scale of the relationship between dust and the rainfall in the South Asian region based on either CMIP5 results or limited number of previous studies. Hence, we would like to emphasize upon the fact that any conclusions drawn on the relationship between the dust load and the South Asian rainfall using model simulation is highly dependent on the degree of complexity incorporated in those models such as the representation of aerosol life cycle, their interaction with clouds, precipitation and other components of the climate system. © 2017, Springer-Verlag Berlin Heidelberg."
"57197711586;","Remote sensing estimation of daily average temperature in northwestern China based on advanced microwave scanning radiometer for the earth observing system",2018,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055751035&partnerID=40&md5=59a8a71ba9dd048b88e00ec7a2bd0b8f","Temperature is one of the most important parameters in the study of the natural environment, hydrology and climate. Remote sensing is often used to estimate air temperature in response to agricultural meteorological disasters to monitor agricultural resources. In this study, we established estimation models using passive microwave remote sensing data. Specifically, the study employed the 6-band brightness temperature data set of the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) over 8 years (2003–2010) and daily average temperature data (field-measured temperature) from meteorological stations within three provinces/regions in Northwestern China (Gansu, Ningxia Hui and Shaanxi). We analysed the influence of site, surface classification and elevation on temperature estimation, investigated changes in the correlation of microwave brightness and field-measured temperatures under sunny and cloudy weather conditions, and established an estimation model by using a multi-band combination. The results showed that the correlation coefficient between microwave brightness and daily average field-measured temperatures differed significantly between single-and multi-band remote sensing data, and between various types of surfaces at different elevations. The correlation between microwave brightness and fieldmeasured temperatures was significantly better without clouds than with clouds; without cloud cover the root mean square error (RMSE) was within the range of 2–3°C. Lastly, the 2011 data that were not involved in the modelling were used to test the accuracy of the model. The findings indicate that the model could be applied to agricultural production (R2 = 0.887). © 2018, Scibulcom Ltd. All rights reserved."
"57192104713;57202087967;57202198906;57202188178;57218661329;","IoT based smart and flexible lightning in streets",2018,"10.14419/ijet.v7i2.8.10426","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047430371&doi=10.14419%2fijet.v7i2.8.10426&partnerID=40&md5=1e1229bdf4c9230656a4f5ea8bc285f1","The internet of Things (IOT) is always giving unprecedented answers for the customary issues looked by man. One of the real obstacles in city is we are spending huge expenses on street light. To control the street lights based on detection of sunlight by implemented with smart embedded system. The paper is mainly utilized for smart and climate adaptive lighting in street lights. The street lights are automatically ON during the evening time and automatically OFF during day time. The street light can be accessed to turn ON or OFF at any place and any time through web. In addition to that On top of the street light we are placing camera to track the activities performed on the street and where the recordings are stored in a server. Furthermore a panic button is placed on the pole, If there is any emergency situations like harassment, robbery there is a panic button is available at the reachable height any person can press it if he is in danger. If people are unable to press the panic button, they should use voice recognition which is connected to panic button, when it recognises some commands like help, it automatically press the panic button. Whenever the panic button is pressed, the footages at that time recorded by the camera is sent straight forwardly to the cloud account. The near specific police headquarters can have access of the account by which they can see the incident's spot. Every region's street lights are associated with the specific area's police headquarters and cloud account can be accessible by each of them. Here GSM Technology is eliminated completely. Safety and energy consumptions can be ensured by this idea. © 2018 Authors."
"57196237174;57213029726;55939316400;","LST retrieval algorithm adapted to the Amazon evergreen forests using MODIS data",2018,"10.1016/j.rse.2017.10.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032390483&doi=10.1016%2fj.rse.2017.10.015&partnerID=40&md5=6f871e7cf61fe123d68c193d005d4932","Amazonian tropical forests play a significant role in global water, carbon and energy cycles. Considering the importance of this biome and climate change projections, the monitoring of vegetation status of these rainforests becomes of significant importance. In this context vegetation temperature is presented as a key variable linked with plant physiology. In particular some studies showed the relationship between this variable and the CO2 absorption capacity and biomass loss of these tropical forests proving the potential use of vegetation temperature in the monitoring of the vegetation status. Nevertheless, the use of thermal remote sensing data over tropical forests still has some limitations being of special importance the atmospheric correction under very humid conditions and the possible high occurrence of cloudy pixels. In order to mitigate these limitations over the Amazon region, we present in this paper a new processing methodology to derive a LST product from Moderate Resolution Imaging Spectroradiometer (MODIS) data. The LST product was generated using a tuned split-window equation and cloud information derived from the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm. This LST product was validated using simulated and in situ data, and intercompared to the MODIS LST standard product (MOD11). Validation analysis shows that the new LST product reduces the RMSE by 0.6 to 1 K when compared to the MODIS standard LST product, mainly because of a reduction of the bias. We also show a preliminary intercomparison between MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) LST spatial patterns to illustrate the feasibility of VIIRS to extend forward the MODIS LST temporal series. © 2017 Elsevier Inc."
"57206499392;56613378100;57202264248;57204498512;7007133231;","Insight into anthropogenic forcing on coastal upwelling off south-central Chile",2018,"10.1525/elementa.314","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055781499&doi=10.1525%2felementa.314&partnerID=40&md5=5e27cb58cbc3b7c48c6f483a166fd5f5","Coastal upwelling systems off the coasts of Peru and Chile are among the most productive marine ecosystems in the world, sustaining a significant percentage of global primary production and fishery yields. Seasonal and interannual variability in these systems has been relatively well documented; however, an understanding of recent trends and the influence of climate change on marine processes such as surface cooling and primary productivity is limited. This study presents evidence that winds favorable to upwelling have increased within the southern boundary of the Humboldt Current System (35°-42°S) in recent decades. This trend is consistent with a poleward movement of the influence of the Southeast Pacific Anticyclone and resembles the spatial pattern projected by Global Circulation Models for warming scenarios. Chlorophyll a levels (from 2002 to present) determined by satellite and field-based time-series observations show a positive trend, mainly in austral spring-summer (December-January-February), potentially explained by observed increments in nutrient flux towards surface waters and photosynthetically active radiation. Both parameters appear to respond to alongshore wind stress and cloud cover in the latitudinal range of 35°S to 42°S. In addition, net annual deepening of the mixed layer depth is estimated using density and temperature profiles. Changes in this depth are associated with increasing winds and may explain cooler, more saline, and more productive surface waters, with the latter potentially causing fluctuations in dissolved oxygen and other gases, such as nitrous oxide, sensitive to changes in oxygenation. We argue that these recent changes represent, at least in part, a regional manifestation of the Anthropocene along the Chilean coast. © 2018 The Author(s)."
"56434851400;7004978125;","Upscale impact of mesoscale disturbances of tropical convection on convectively coupled Kelvin waves",2018,"10.1175/JAS-D-17-0178.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040930944&doi=10.1175%2fJAS-D-17-0178.1&partnerID=40&md5=a9bb6238a2ef43069f2800228e5d6567","Tropical convection associated with convectively coupled Kelvin waves (CCKWs) is typically organized by an eastward-moving synoptic-scale convective envelope with numerous embedded westward-moving mesoscale disturbances. Such a multiscale structure of tropical convection is a challenge for present-day cloud-resolving simulations and its representation in global climate models. It is of central importance to assess the upscale impact of mesoscale disturbances on CCKWs as mesoscale disturbances propagate at various tilt angles and speeds. Besides, it is still poorly understood whether the front-to-rear-tilted vertical structure of CCKWs can be induced by the upscale impact of mesoscale disturbances in the presence of upright mean heating. Here, a simple multiscale model is used to capture this multiscale structure, where mesoscale fluctuations are directly driven by mesoscale heating and synoptic-scale circulation is forced by mean heating and eddy transfer of momentum and temperature. The results show that the upscale impact of mesoscale disturbances that propagate at tilt angles of 110°-250° induces negative lower-tropospheric potential temperature anomalies in the leading edge, providing favorable conditions for shallow convection in a moist environment, while the remaining tilt-angle cases have opposite effects. Even in the presence of upright mean heating, the front-to-rear-tilted synoptic-scale circulation can still be induced by eddy terms at tilt angles of 120°-240°. In the case with fast-propagating mesoscale heating, positive potential temperature anomalies are induced in the lower troposphere, suppressing convection in a moist environment. This simple model also reproduces convective momentum transport and CCKWs in agreement with results from a recent cloud-resolving simulation. © 2018 American Meteorological Society."
"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."
"57195247905;8080847900;","Aerosol-radiation interaction in atmospheric models: Idealized sensitivity study of simulated short-wave direct radiative effects to particle microphysical properties",2018,"10.1016/j.jaerosci.2017.10.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032738925&doi=10.1016%2fj.jaerosci.2017.10.004&partnerID=40&md5=6df0ad1d9a85a07175340fbd74c3d45c","We assessed the impact of the microphysical parameterization of natural and anthropogenic aerosols on simulated short-wave radiative effects due to Aerosol-Radiation Interaction (ARI). Layer radiative properties (optical depth, single scattering albedo and asymmetry factor) of dry mineral dust, organic carbon and a black carbon-sulfate mixture have been calculated with a T-matrix code in the short-wave spectral region, after perturbing relevant particle microphysical properties (size distribution, refractive index, mixing state). For each aerosol species, an idealized atmospheric layer and three events of increasing intensity have been set. Then, short-wave direct radiative effects (clear-sky) have been simulated at the top-of-atmosphere (TOA) and at surface (SFC) using the radiative transfer model RRTMG_SW (widely used in atmospheric models), separately for each aerosol species. We observed considerably variable impacts of the particle microphysical perturbations on the layer radiative properties for mineral dust and organic carbon, mainly due to the different sizes of the two species. For the black carbon-sulfate mixture, the single scattering albedo has been found to be much lower in the internal mixing case. Regarding the direct radiative effects, we observed perturbation-induced variability ranges (evaluated against the base net fluxes in absence of aerosols) always within the perturbation range set for the particle microphysical properties (±20% →40%). This work, therefore, quantitatively demonstrates that small uncertainties on the aerosol microphysical parameterization propagate on the simulated direct radiative effects mainly with a loss of strength. Considerable perturbation-induced absolute variations of the direct radiative effects have been found (above all for large aerosol amounts), which could significantly affect the model assessments of the ARI radiative effects and therefore meteorological forecasts and climate predictions. © 2017 Elsevier Ltd"
"6506347229;22936284300;23396709900;","Role of fog in urban heat island modification in Kraków, Poland",2018,"10.4209/aaqr.2016.12.0581","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040973822&doi=10.4209%2faaqr.2016.12.0581&partnerID=40&md5=1978ca4bb0cd44556308b58043b65015","The impact of fog on relief modified urban heat island (RMUHI) in Kraków has been presented using fog observations at 06 UTC from two meteorological stations: a rural one (Balice, B) and an urban one (Botanical Garden, BG) from the period 2006–2015. Daily UHI magnitude for the valley floor for the same period was estimated as TminBG–TminB, while for the period 2010–2015, eight daily courses of UHI were available, for the urban areas in the valley floor and 50 m above it, together with air temperature inversion data. UHI data for days with various combinations of fog occurrence and weather conditions were compared using non-parametric statistical tests: Wald-Wolfowitz test, Kolmogorov-Smirnov test and U Mann-Whitney test. Data of 2010–2015 were also the subject of cluster analysis (k-means method). Fog is an important factor decreasing UHI magnitude by about 1 K but mainly during weather conditions with little or no cloudiness and small wind speed or atmospheric calm, during anticyclonic synoptic situations, and only in the valley floor areas. With an increase in cloudiness and wind speed, the role of fog decreases and is similar in all parts of the city. © Taiwan Association for Aerosol Research."
"56038223500;9842163500;26039315200;7007042259;","Burned area detection based on Landsat time series in savannas of southern Burkina Faso",2018,"10.1016/j.jag.2017.09.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032229011&doi=10.1016%2fj.jag.2017.09.011&partnerID=40&md5=f30b3f662cc8d43656e77cefc8d59ca1","West African savannas are subject to regular fires, which have impacts on vegetation structure, biodiversity and carbon balance. An efficient and accurate mapping of burned area associated with seasonal fires can greatly benefit decision making in land management. Since coarse resolution burned area products cannot meet the accuracy needed for fire management and climate modelling at local scales, the medium resolution Landsat data is a promising alternative for local scale studies. In this study, we developed an algorithm for continuous monitoring of annual burned areas using Landsat time series. The algorithm is based on burned pixel detection using harmonic model fitting with Landsat time series and breakpoint identification in the time series data. This approach was tested in a savanna area in southern Burkina Faso using 281 images acquired between October 2000 and April 2016. An overall accuracy of 79.2% was obtained with balanced omission and commission errors. This represents a significant improvement in comparison with MODIS burned area product (67.6%), which had more omission errors than commission errors, indicating underestimation of the total burned area. By observing the spatial distribution of burned areas, we found that the Landsat based method misclassified cropland and cloud shadows as burned areas due to the similar spectral response, and MODIS burned area product omitted small and fragmented burned areas. The proposed algorithm is flexible and robust against decreased data availability caused by clouds and Landsat 7 missing lines, therefore having a high potential for being applied in other landscapes in future studies. © 2017 Elsevier B.V."
"15080711500;","Actual sunshine duration in Poland - Comparison of satellite and ground-based measurements",2018,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061587381&partnerID=40&md5=9138f2392bed098b6784c995a1ab56fc","The objective of the study was to compare the sum of actual sunshine duration in Poland, based on satellite and ground-based measurements during the period of 1983-2015. Results from the first group of data were derived from sunshine duration measurements from 44 surface synoptic stations belonging to the Polish Institute of Meteorology and Water Management (IMGW-PIB). The second group of data includes values from observations of Meteosat geostationary satellites (SARAH-2 climate data record), provided by the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF). The study showed that in Poland, values of linear correlation coefficients (r) between both datasets are high, and range between 0.80 and 0.95. Differences in daily sums of sunshine duration are low, with the prevalence of positive deviations, i.e. slightly higher values for satellite data. The largest positive deviations were found in Tarnów, Zielona Góra, and Racibórz (+0.3 h), with equivalent negative deviations in Warsaw and on Kasprowy Wierch (-0.4 h). Moreover, minor discrepancies were found for the long-term variability of the mean annual sums of actual sunshine duration. However, after 1995, the deviations were insignificant, and averaged 4 hours. Differences between both data series are caused by several factors, including an underestimation of aerosols optical depth (AOD), as well as the failure to consider the type of clouds covering the Sun's disc. With its high spatial resolution (0.05° x 0.05°), the satellite data can be a valuable source of information, particularly in regional studies of the spatial variation of sunshine duration. © 2018 Przeglad Geofizyczny."
"55429274700;56480014400;8632802100;8832995400;7404454238;9249627300;55418932600;36918460600;36994251800;35339913600;","Impact of spatial resolution on simulated consecutive dry days and near-surface temperature over the central mountains in Japan",2018,"10.2151/sola.2018-008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045622544&doi=10.2151%2fsola.2018-008&partnerID=40&md5=de704f307588a6e6dc29bc535a662494","To evaluate the influence of spatial resolution in numerical simulations on the duration of consecutive dry days (CDDs) and near-surface temperature over the central mountains in Japan, a regional climate model was used to conduct two experiments with horizontal resolutions of 5 and 20 km. Compared with observations, the spatial and temporal features of the CDDs were simulated well in the 5 km experiment, whereas in the 20 km simulation they were overestimated over the mountains and underestimated in the surrounding regions. The accuracy in the simulated CDDs affected the near-surface temperature in the model. In years with a difference of more than five days in the CDDs between the 5 and 20 km experiments, near-surface temperatures over the mountains were 0.2-0.3 K lower in the 5 km simulation compared with the 20 km simulation. This was due to the lower number of CDDs in 5 km simulation causing active cloud convection and reduced net radiation at the ground, resulting from a large decrease in the solar radiation at the ground. In addition, a land surface wetness controls a spatial heterogeneity of temperature difference between two experiments. © The Author(s) 2018."
"57191254599;56208659000;6506407293;6603340358;25634932400;","Dendrochronological reconstruction of environmental history of Fagus Grandifolia Subsp. Mexicana in Mexico",2018,"10.3959/1536-1098-74.1.108","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042542221&doi=10.3959%2f1536-1098-74.1.108&partnerID=40&md5=1b439c0254f7dbede7e0f8f774741ac9","Growth-ring analysis is a valuable source of information for reconstructing environmental history. In this study, ring-width series of a sample of Fagus grandifolia subsp. Mexicana were used to identify the main events that have affected populations of this species. Core samples were extracted in three representative beech forests in Mexico. These are forests where F. grandifolia subsp. Mexicana dominates the canopy. A total of 3355 years of growth rings were measured and three ring-width chronologies were generated. Average annual ring widths were similar between the three sites and ranged from 0.98 to 1.08 mm. A pattern of multiple suppressions and releases was observed, mainly associated with local events, but with a slight climatic influence. Correlations between the ring-width index and climate variables were not statistically significant, with the exception of a seasonal January-June precipitation pattern (1982-2001). There has not been a large-scale disturbance of natural or human origin in the beech forests of the state of Hidalgo in the past 150 years, except in El Gosco, where anthropogenic disturbances have increased in the past decade. © 2018 by The Tree-Ring Society."
"6603969535;57200410677;57200414403;57200416152;57200421154;57200410183;57191477224;","Temporal variability of the Charlotte (sub)urban heat Island",2018,"10.1175/JAMC-D-17-0099.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041240186&doi=10.1175%2fJAMC-D-17-0099.1&partnerID=40&md5=40374111c0b70e7e85facde6fe97835b","A multiscale temporal analysis of the urban heat island (UHI) for a large, rapidly growing, subtropical city (Charlotte, North Carolina) is conducted using hourly surface observations from a regional network of 12 weather and air-quality stations over a 5-yr period and monthly mean surface temperatures from two stations over a 40-yr period. Each station was classified as urban, suburban, or rural after detailed site analysis. During the 5-yr period, from temperature differences between the most central urban site and the rural reference site, over 70% of nights exhibited prominent nocturnal UHIs. The most intense UHIs occurred on winter nights with light winds, clear skies, low humidity, strong low-level stability, and no precipitation or frontal passage. The UHI maxima occurred either just after sunset or near sunrise. Maximum urban and rural cooling rates occurred within a few hours of sunset, but rural maxima were larger and preceded (by 1-2 h) the urban maxima. Daily variations in nocturnal mean UHI intensity exhibited significant positive correlations with cloud-base height, atmospheric stability, NO2 concentration, and total solar radiation and significant negative correlations with relative humidity, wind speed, and cloud cover. When optimal weather for UHI development was present, UHIs were more intense on weekdays than on weekends. During the 40-yr period, an appreciable positive trend in UHI intensity occurred. These results support the notion that weather, air pollution, and urban form change can significantly modulate UHI intensities. Similarities and differences between the Charlotte UHI and those observed in similar cities are discussed. © 2018 American Meteorological Society."
"8906042800;35740099400;7006173068;7006815674;","Seasonal forecasting of onset of summer rains over South Africa",2018,"10.1175/JAMC-D-18-0067.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058213399&doi=10.1175%2fJAMC-D-18-0067.1&partnerID=40&md5=2d8339c8e677373168508cac472987fa","In this study, we attempted to forecast the onset of summer rains over South Africa using seasonal precipitation forecasts generated by the Scale Interaction Experiment-Frontier Research Center for Global Change, version 2 (SINTEX-F2), seasonal forecasting system. The precipitation forecasts of the 12-member SINTEX-F2 system, initialized on 1 August and covering the period 1998-2015, were used for the study. The SINTEX-F2 forecast precipitation was also downscaled using dynamical and statistical techniques to improve the spatial and temporal representation of the forecasts. The Weather Research and Forecasting (WRF) Model with two cumulus parameterization schemes was used to dynamically downscale the SINTEX-F2 forecasts. The WRF and SINTEX-F2 precipitation forecasts were corrected for biases using a linear scaling method with a 31-day moving window. The results indicate the onset dates derived from the raw and bias-corrected model precipitation forecasts to have realistic spatial distribution over South Africa. However, the forecast onset dates have root-mean-square errors of more than 30 days over most parts of South Africa except over the northeastern province of Limpopo and over the Highveld region of Mpumalanga province, where the root-mean-square errors are about 10-15 days. The WRF Model with Kain-Fritsch cumulus scheme (bias-corrected SINTEX-F2) has better performance in forecasting the onset dates over Limpopo (the Highveld region) compared to other models, thereby indicating the forecast of onset dates over different regions of South Africa to be model dependent. The results of this study are important for improving the forecast of onset dates over South Africa. © 2018 American Meteorological Society."
"15137475500;6602406924;24481754700;49461661700;57204759853;","A method for deriving aerosol optical depth from meteorological satellite data",2018,"10.2495/AIR180061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057022708&doi=10.2495%2fAIR180061&partnerID=40&md5=d67ebbc438960678c89045371632d691","Aerosols are important agent of radiative forcing and climate disturbance, especially in a polluted environment. In general, the impact of aerosol on the climate depends on aerosol optical properties. One of important aerosol optical properties is aerosol optical depth (AOD). In general, AOD can be measured using ground-based sunphotometers. However, it is costly to deploy such instruments over a large area. Due to a lack of comprehensive measurement on a global scale, retrieval of aerosol information from some instruments on board satellites (e.g. MODIS and POLDER) has been developed. However, aerosol information from such satellites has relatively short historical records. In addition, such information is available only once or twice a day. Therefore, in this work, we propose a method for deriving AOD from meteorological geostationary satellite data. This is because geostationary satellites have advantage that they have longer historical data and their data are available on the hourly basis. According to the proposed method, a radiative transfer model, namely 6S, was used to construct series of look up tables (LUT) which contained pre-computed datasets including earth-atmospheric reflectivity, aerosol information and surface albedo. The satellite images in a visible channel were used to calculate the earth-atmospheric reflectivity data and these data were later employed as the main input of the method. In addition, the infrared images from the satellite were also used to identify cloud scene over the area. The value of AOD, which makes the value of the earth-atmospheric reflectivity from the LUT matching to the earth-atmospheric reflectivity obtained from the satellite data, will be considered as the true AOD. For the validation, the calculated AOD from this method was compared with the ground-based AOD measurements from NASA-AERONET. It was found that the measured and calculated AOD were in reasonable agreement. © 2018 WIT Press."
"57197731999;7004234223;","Espeletia giant rosette plants are reliable biological indicators of time since fire in andean grasslands",2018,"10.1007/s11258-017-0779-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046836209&doi=10.1007%2fs11258-017-0779-x&partnerID=40&md5=88cf774f5a7ccb25f8c4b2c9f7c579fc","Páramo grasslands in the tropical Andes are fire-prone ecosystems and an understanding of their fire ecology is fundamental to biodiversity conservation and ecosystem management. Fire registers are normally impractical in these remote, cloud-covered landscapes, but Espeletia giant rosette plants have been proposed as biological indicators of time since fire in páramos. Espeletia giant stem rosettes tolerate fire well, protecting apical buds in at the heart of their leaf rosettes, and for some species, germination is known to be enhanced by fire. As the plant grows, its dead leaves remain attached to the stem, but fire removes these and resets the ‘‘leaf clock’’. This study uses a unique register of fires in one Ecuadorian páramo to assess the robustness of this biological indicator. Dead leaf cover on Espeletia pycnophylla giant rosette plants was measured in fifteen different sites with known fire dates from 2000 to 2014. The growth rates of plants at four different elevations were measured over a 2-year period and used to estimate time since fire based on dead leaf cover in the known sites. Estimates were accurate to ± 2 year. Thus, where fire records are missing, relatively easy measurements of growth rates and dead leaf cover of Espeletia giant rosette plants can provide reliable estimates across a wide range of times since fire. This approach has value for direct investigations into fire ecology but also for studies in which controlling for fire dynamics is necessary to reveal underlying patterns. Therefore, this approach also offers a means to obtain better information on other landscape-scale processes such as the impact of climate change on biodiversity or the provision of ecosystem services. © Springer Science+Business Media B.V., part of Springer Nature 2017."
"7401794766;","Mapping land use on Irish peatlands using medium resolution satellite imagery",2018,"10.2014/igj.v51i2.1371","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064764826&doi=10.2014%2figj.v51i2.1371&partnerID=40&md5=06f324d128145a64899c343ec49ddec3","The EU is committed to quantifying greenhouse gas emissions and removals from land use, land use change and forestry, including wetlands. Wetlands and peatlands will play a central role in achieving temperature goals agreed in the Paris Agreement. Throughout Europe and particularly in Ireland, peatlands have been under severe strain for decades. Irish peatlands cover about 20.6% of the land and up to 85% are degraded. Medium resolution satellite data were analysed using a combination of object-based image assessment and peatland maps to produce land use maps for the 2005 to 2006 period. Four peatland land use types were detected: grassland, forestry, industrial peat production, and residual peat. Persistent cloud was an issue along the western seaboard and peatlands in these areas were excluded from the analysis. Despite this issue, the results show that 66% of peatlands have undergone land use change: 35% to grassland; 27% to forestry; and 4% to industrial. The overall map accuracy was 77%. The results could be used to aid the development of baseline data on peatland land use in Ireland for the 2005-2009 base period as required by the 2030 Climate and Energy Framework. The methodology may be used to quantify land use and land use change on peatlands across the EU. © 2018, Geographical Society of Ireland. All rights reserved."
"14826864700;6507121473;6602497877;57189060131;15846971700;36059786200;55619258500;8719703500;","The severe hailstorm in southwest Germany on 28 July 2013: characteristics, impacts and meteorological conditions",2018,"10.1002/qj.3197","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042312916&doi=10.1002%2fqj.3197&partnerID=40&md5=0880ef0e688c6019b11ceab0358546da","At the end of July 2013, a series of severe thunderstorms associated with heavy rainfall, severe wind gusts and large hail affected parts of Germany. On 28 July 2013, two supercells formed almost simultaneously in southern Germany, from which only the more southerly cell produced hailstones up to 10 cm in diameter on a hailswath approximately 120 km long and 15–20 km wide. For the insurance industry, this event, with losses of more than EUR 1 billion, was one of the most expensive natural disasters that has ever occurred in Germany. This article investigates the creation, temporal evolution and effects of the most severe supercell that day by considering and merging radar and satellite data, eyewitness reports, insurance loss data and numerical model studies. Observations of hail at ground level fit very well with a cold-ring-shaped structure in the cloud-top brightness temperature observed by a geostationary satellite imager. Various simulations conducted with the convection-permitting COnsortium for Small-scale MOdeling (COSMO) revealed that the track of the hailstorm could be reproduced only when convection was triggered artificially by two warm bubbles that produced single cells that were precursors of the supercell. The model results suggested that the supercell developed near a pre-existing single cell through low-level flow convergence in an environment with moderate CAPE but substantial wind shear and storm-relative helicity, both of which persisted for several hours in the area in which the supercell moved. © 2017 Royal Meteorological Society"
"56468061700;56033244700;57188658530;57203326554;","Role of extratropical cyclones in the recently observed increase in poleward moisture transport into the Arctic Ocean",2018,"10.1007/s00376-017-7116-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037335080&doi=10.1007%2fs00376-017-7116-0&partnerID=40&md5=ea30a27e4da97a614cd5cede12198eee","Poleward atmospheric moisture transport (AMT) into the Arctic Ocean can change atmospheric moisture or water vapor content and cause cloud formation and redistribution, which may change downward longwave radiation and, in turn, surface energy budgets, air temperatures, and sea-ice production and melt. In this study, we found a consistently enhanced poleward AMT across 60°N since 1959 based on the NCAR–NCEP reanalysis. Regional analysis demonstrates that the poleward AMT predominantly occurs over the North Atlantic and North Pacific regions, contributing about 57% and 32%, respectively, to the total transport. To improve our understanding of the driving force for this enhanced poleward AMT, we explored the role that extratropical cyclone activity may play. Climatologically, about 207 extratropical cyclones move across 60°N into the Arctic Ocean each year, among which about 66 (32% of the total) and 47 (23%) originate from the North Atlantic and North Pacific Ocean, respectively. When analyzing the linear trends of the time series constructed by using a 20-year running window, we found a positive correlation of 0.70 between poleward yearly AMT and the integrated cyclone activity index (measurement of cyclone intensity, number, and duration). This shows the consistent multidecadal changes between these two parameters and may suggest cyclone activity plays a driving role in the enhanced poleward AMT. Furthermore, a composite analysis indicates that intensification and poleward extension of the Icelandic low and accompanying strengthened cyclone activity play an important role in enhancing poleward AMT over the North Atlantic region. © 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."
"8931278800;57190010696;57196465098;56606464400;","Validation on MERSI/FY-3A precipitable water vapor product",2018,"10.1016/j.asr.2017.10.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033479148&doi=10.1016%2fj.asr.2017.10.005&partnerID=40&md5=e9609594b18e67ff1e4e59de39059420","The precipitable water vapor is one of the most active gases in the atmosphere which strongly affects the climate. China's second-generation polar orbit meteorological satellite FY-3A equipped with a Medium Resolution Spectral Imager (MERSI) is able to detect atmospheric water vapor. In this paper, water vapor data from AERONET, radiosonde and MODIS were used to validate the accuracy of the MERSI water vapor product in the different seasons and climatic regions of East Asia. The results show that the values of MERSI water vapor product are relatively lower than that of the other instruments and its accuracy is generally lower. The mean bias (MB) was −0.8 to −12.7 mm, the root mean square error (RMSE) was 2.2–17.0 mm, and the mean absolute percentage error (MAPE) varied from 31.8% to 44.1%. On the spatial variation, the accuracy of MERSI water vapor product in a descending order was from North China, West China, Japan -Korea, East China, to South China, while the seasonal variation of accuracy was the best for winter, followed by spring, then in autumn and the lowest in summer. It was found that the errors of MERSI water vapor product was mainly due to the low accuracy of radiation calibration of the MERSI absorption channel, along with the inaccurate look-up table of apparent reflectance and water vapor within the water vapor retrieved algorithm. In addition, the surface reflectance, the mixed pixels of image cloud, the humidity and temperature of atmospheric vertical profile and the haze were also found to have affected the accuracy of MERSI water vapor product. © 2017 COSPAR"
"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."
"56464971600;57015826100;7004479957;23991212200;","Sensitivity of Coupled Tropical Pacific Model Biases to Convective Parameterization in CESM1",2018,"10.1002/2017MS001176","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040538306&doi=10.1002%2f2017MS001176&partnerID=40&md5=5c66f484a3695e152f1d59fc59ed627e","Six month coupled hindcasts show the central equatorial Pacific cold tongue bias development in a GCM to be sensitive to the atmospheric convective parameterization employed. Simulations using the standard configuration of the Community Earth System Model version 1 (CESM1) develop a cold bias in equatorial Pacific sea surface temperatures (SSTs) within the first two months of integration due to anomalous ocean advection driven by overly strong easterly surface wind stress along the equator. Disabling the deep convection parameterization enhances the zonal pressure gradient leading to stronger zonal wind stress and a stronger equatorial SST bias, highlighting the role of pressure gradients in determining the strength of the cold bias. Superparameterized hindcasts show reduced SST bias in the cold tongue region due to a reduction in surface easterlies despite simulating an excessively strong low-level jet at 1-1.5 km elevation. This reflects inadequate vertical mixing of zonal momentum from the absence of convective momentum transport in the superparameterized model. Standard CESM1simulations modified to omit shallow convective momentum transport reproduce the superparameterized low-level wind bias and associated equatorial SST pattern. Further superparameterized simulations using a three-dimensional cloud resolving model capable of producing realistic momentum transport simulate a cold tongue similar to the default CESM1. These findings imply convective momentum fluxes may be an underappreciated mechanism for controlling the strength of the equatorial cold tongue. Despite the sensitivity of equatorial SST to these changes in convective parameterization, the east Pacific double-Intertropical Convergence Zone rainfall bias persists in all simulations presented in this study. © 2017. The Authors."
"36508552200;6507025594;57190727602;","Two years observations on the diurnal evolution of coastal atmospheric boundary layer features over Thiruvananthapuram (8.5∘ N, 76.9∘ E), India",2018,"10.1007/s00704-016-1955-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990944414&doi=10.1007%2fs00704-016-1955-y&partnerID=40&md5=47400af3a604beba8e21a40922c8e3ee","The atmospheric boundary layer (ABL) over a given coastal station is influenced by the presence of mesoscale sea breeze circulation, together with the local and synoptic weather, which directly or indirectly modulate the vertical thickness of ABL (zABL). Despite its importance in the characterization of lower tropospheric processes and atmospheric modeling studies, a reliable climatology on the temporal evolution of zABL is not available over the tropics. Here, we investigate the challenges involved in determination of the ABL heights, and discuss an objective method to define the vertical structure of coastal ABL. The study presents a two year morphology on the diurnal evolution of the vertical thickness of sea breeze flow (zSBF) and zABL in association with the altitudes of lifting condensation level (zLCL) over Thiruvananthapuram (8.5∘ N, 76.9∘ E), a representative coastal station on the western coastline of the Indian sub-continent. We make use of about 516 balloon-borne GPS sonde measurements in the present study, which were carried out as part of the tropical tropopause dynamics field experiment under the climate and weather of the sun-earth system (CAWSES)–India program. Results obtained from the present study reveal major differences in the temporal evolution of the ABL features in relation to the strength of sea breeze circulation and monsoonal wind flow during the winter and summer monsoon respectively. The diurnal evolution in zABL is very prominent in the winter monsoon as against the summer monsoon, which is attributed to the impact of large-scale monsoonal flow over the surface layer meteorology. For a majority of the database, the zLCL altitudes are found to be higher than that of the zABL, indicating a possible decoupling of the ABL with the low-level clouds. © 2016, Springer-Verlag Wien."