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."
"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."
"35221443100;36106335800;15318900900;56190076100;57196309273;55717074000;57192212652;36105812700;7501627905;","Effective radiative forcing in the aerosol-climate model CAM5.3-MARC-ARG",2018,"10.5194/acp-18-15783-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056089815&doi=10.5194%2facp-18-15783-2018&partnerID=40&md5=a7b82a68d2835a7a976370bb3712e18d","We quantify the effective radiative forcing (ERF) of anthropogenic aerosols modelled by the aerosol-climate model CAM5.3-MARC-ARG. CAM5.3-MARC-ARG is a new configuration of the Community Atmosphere Model version 5.3 (CAM5.3) in which the default aerosol module has been replaced by the two-Moment, Multi-Modal, Mixing-state-resolving Aerosol model for Research of Climate (MARC). CAM5.3-MARC-ARG uses the ARG aerosol-activation scheme, consistent with the default configuration of CAM5.3. We compute differences between simulations using year-1850 aerosol emissions and simulations using year-2000 aerosol emissions in order to assess the radiative effects of anthropogenic aerosols. We compare the aerosol lifetimes, aerosol column burdens, cloud properties, and radiative effects produced by CAM5.3-MARC-ARG with those produced by the default configuration of CAM5.3, which uses the modal aerosol module with three log-normal modes (MAM3), and a configuration using the modal aerosol module with seven log-normal modes (MAM7). Compared with MAM3 and MAM7, we find that MARC produces stronger cooling via the direct radiative effect, the shortwave cloud radiative effect, and the surface albedo radiative effect; similarly, MARC produces stronger warming via the longwave cloud radiative effect. Overall, MARC produces a global mean net ERF of-1.79±0.03 W m-2, which is stronger than the global mean net ERF of-1.57±0.04 W m-2 produced by MAM3 and-1.53±0.04 W m-2 produced by MAM7. The regional distribution of ERF also differs between MARC and MAM3, largely due to differences in the regional distribution of the shortwave cloud radiative effect. We conclude that the specific representation of aerosols in global climate models, including aerosol mixing state, has important implications for climate modelling. © 2018 Author(s)."
"57033686900;7202145115;","Balanced Cloud Radiative Effects Across a Range of Dynamical Conditions Over the Tropical West Pacific",2018,"10.1029/2018GL080046","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055937280&doi=10.1029%2f2018GL080046&partnerID=40&md5=009e43eb959694727f843ae90deb2104","Instantaneous relationships between clouds and large-scale vertical motion are used to study the impact of circulation on the near cancellation of cloud radiative effects that is observed over the tropical west Pacific Ocean. The coverage of deep-convective clouds increases with stronger upward motion, but the proportion of thick, medium, and thin anvil cloud remains nearly constant. Thus, when averaging over scales larger than individual storms, the top-of-atmosphere net radiation is only weakly sensitive to the large-scale flow. The balance in cloud radiative effects is therefore maintained across a wide range of large-scale circulations. The ability of the Community Atmosphere Model Version 5 to reproduce the observed cloud-circulation relationships is investigated. The simulated convective clouds substantially overestimate the proportion of deep and optically thick cloud and underestimate the proportion of anvil cirrus. These results demonstrate that simulating key properties of deep-convective clouds remains challenging for some state-of-the-art climate models. ©2018. American Geophysical Union. All Rights Reserved."
"14622650300;7404548584;7102820305;7004472118;7005399437;57203378050;7101984634;","Assessing the Challenges of Surface-Level Aerosol Mass Estimates From Remote Sensing During the SEAC4RS and SEARCH Campaigns: Baseline Surface Observations and Remote Sensing in the Southeastern United States",2018,"10.1029/2017JD028074","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050829247&doi=10.1029%2f2017JD028074&partnerID=40&md5=fcbf598382fb2f3ceff98032f379cc81","The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign conducted in the southeast United States (SEUS) during the summer of 2013 provided a singular opportunity to study local aerosol chemistry and investigate aerosol radiative properties and PM2.5 relationships, focusing on the complexities involved in simplifying the relationship into a linear regression. We utilize three Southeastern Aerosol Research and Characterization network sites and one Environmental Protection Agency Chemical Speciation Network station that afforded simultaneous Aerosol Robotic Network (AERONET) aerosol optical depth (AOD) and aerosol mass, chemistry, and light scattering monitoring. Prediction of AERONET AOD using linear regression of daily-mean PM2.5 during the SEAC4RS campaign yielded r2 of 0.36–0.53 and highly variable slopes across four sites. There were further reductions in PM2.5 predictive skill using Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpetroRadiometer (MISR) AOD data, which have shorter correlation lengths and times relative to surface PM2.5. Long-term trends in aerosol chemistry and optical properties in the SEUS are also investigated and compared to SEAC4RS period data, establishing that the SEUS experienced significant reduction in aerosol mass, corresponding with changes in both aerosol chemistry and optical properties. These changes have substantial impact on the PM2.5-AOD linear regression relationship and reinforce the need for long-term aerosol observation stations in addition to concentrated field campaigns. ©2018. The Authors."
"36466972400;7403931916;7003609063;36095558300;6602513845;7201826462;35468686100;","Improvement of the simulation of cloud longwave scattering in broadband radiative transfer models",2018,"10.1175/JAS-D-18-0014.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049779834&doi=10.1175%2fJAS-D-18-0014.1&partnerID=40&md5=917ab711c9850b5b1007b319d5009872","Cloud longwave scattering is generally neglected in general circulation models (GCMs), but it plays a significant and highly uncertain role in the atmospheric energy budget as demonstrated in recent studies. To reduce the errors caused by neglecting cloud longwave scattering, two new radiance adjustment methods are developed that retain the computational efficiency of broadband radiative transfer simulations. In particular, two existing scaling methods and the two new adjustment methods are implemented in the Rapid Radiative Transfer Model (RRTM). The results are then compared with those based on the Discrete Ordinate Radiative Transfer model (DISORT) that explicitly accounts for multiple scattering by clouds. The two scaling methods are shown to improve the accuracy of radiative transfer simulations for optically thin clouds but not effectively for optically thick clouds. However, the adjustment methods reduce computational errors over a wide range, from optically thin to thick clouds. With the adjustment methods, the errors resulting from neglecting cloud longwave scattering are reduced to less than 2 W m-2 for the upward irradiance at the top of the atmosphere and less than 0.5 W m-2 for the surface downward irradiance. The adjustment schemes prove to be more accurate and efficient than a four-stream approximation that explicitly accounts for multiple scattering. The neglect of cloud longwave scattering results in an underestimate of the surface downward irradiance (cooling effect), but the errors are almost eliminated by the adjustment methods (warming effect). © 2018 American Meteorological Society."
"36657850900;55688930000;55087038900;30967646900;56162305900;55720018700;15755995900;7006705919;","Local Radiative Feedbacks Over the Arctic Based on Observed Short-Term Climate Variations",2018,"10.1029/2018GL077852","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048988350&doi=10.1029%2f2018GL077852&partnerID=40&md5=fbf46fd35caf8f3e0f26de7ba9db79db","We compare various radiative feedbacks over the Arctic (60–90°N) estimated from short-term climate variations occurring in reanalysis, satellite, and global climate model data sets using the combined Kernel-Gregory approach. The lapse rate and surface albedo feedbacks are positive, and their magnitudes are comparable. Relative to the tropics (30°S–30°N), the lapse rate feedback is the largest contributor to Arctic amplification among all feedbacks, followed by surface albedo feedback and Planck feedback deviation from its global mean. Both shortwave and longwave water vapor feedbacks are positive, leading to a significant positive net water vapor feedback over the Arctic. The net cloud feedback has large uncertainties including its sign, which strongly depends on the data used for all-sky and clear-sky radiative fluxes at the top of the atmosphere, the time periods considered, and the methods used to estimate the cloud feedback. ©2018. American Geophysical Union. All Rights Reserved."
"38561188200;57112070700;56014511300;","Control of ITCZ Width by Low-Level Radiative Heating From Upper-Level Clouds in Aquaplanet Simulations",2018,"10.1029/2018GL078292","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048956967&doi=10.1029%2f2018GL078292&partnerID=40&md5=ff0767bb0f3ccdbdfaedabe87155b464","Atmospheric cloud radiative effects (ACRE) narrow the Intertropical Convergence Zones (ITCZs) in climate models. Some studies have attributed this to the upper tropospheric heating by deep clouds. We report two types of idealized aquaplanet experiments, one where ACRE in specific altitude ranges is removed and another where the ACRE associated with clouds in specific altitude ranges is removed. Lower tropospheric heating due to upper tropospheric clouds in the deep tropics exerts the greatest impact on the ITCZ width and meridional overturning, even though the heating is weaker than in the upper troposphere. It is argued that this is because radiatively driven changes in the shallow circulation drive a feedback via net import of MSE and make the ITCZ more unstable in its core, thereby forcing the ITCZ to contract. The radiative effects of clouds in the subsiding subtropics are found to be of secondary importance in driving the necessary circulation changes. ©2018. American Geophysical Union. All Rights Reserved."
"57192180109;56250119900;7004587644;57211565887;55796882100;","Regional Regime-Based Evaluation of Present-Day General Circulation Model Cloud Simulations Using Self-Organizing Maps",2018,"10.1002/2017JD028196","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047472096&doi=10.1002%2f2017JD028196&partnerID=40&md5=bfe7e7c1a6122da8bc0f85aedfc0304c","Global clusters are derived by applying the self-organizing map technique to the Moderate Resolution Imaging Spectroradiometer cloud top pressure-cloud optical thickness joint histograms. These cloud clusters are then used to classify Cloud Feedback Model Intercomparison Project Observation Simulator Package output from the HadGEM3 (Global Atmosphere version 7) atmosphere-only climate model. Discrepancies in the Global Atmosphere version 7 representation of particular clusters can be established by examining the two sets of cluster's occurrence rate and radiative effect. The overall differences in the occurrence rates show major discrepancies in several of the clusters, resulting in a shift from five dominant clusters in Moderate Resolution Imaging Spectroradiometer (above 10% occurrence rate) to two dominant clusters in the model. A comparison of the geographic distributions of occurrence rate shows that the differences are strongly regional and unique to each cluster. While comparisons of the global mean longwave and shortwave cloud radiative effect (CRE) show strong agreement, examination of the CRE of individual cloud types reveals larger errors that highlight the role of compensating errors in masking model deficiencies. CRE data for each of the clusters is further partitioned into regions. This establishes that the bias associated with a cluster is highly variable globally, with no clusters showing consistent biases across all regions. Therefore, regional level phenomena likely play an important role in the creation of these errors. ©2018. American Geophysical Union. All Rights Reserved."
"57204833386;7201504886;","Observing the tropical atmosphere in moisture space",2018,"10.1175/JAS-D-17-0375.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057355483&doi=10.1175%2fJAS-D-17-0375.1&partnerID=40&md5=88d557495b6c0f122056c9903d2bd9d9","Measurements from the Barbados Cloud Observatory are analyzed to identify the processes influencing the distribution of moist static energy and the large-scale organization of tropical convection. Five years of water vapor and cloud profiles from a Raman lidar and cloud radar are composed to construct the structure of the observed atmosphere in moisture space. The large-scale structure of the atmosphere is similar to that now familiar from idealized studies of convective self-aggregation, with shallow clouds prevailing over a moist marine layer in regions of low-rank humidity, and deep convection in a nearly saturated atmosphere in regions of high-rank humidity. With supplementary reanalysis datasets the overall circulation pattern is reconstructed in moisture space, and shows evidence of a substantial lower-tropospheric component to the circulation. This shallow component of the circulation helps support the differentiation between the moist and dry columns, similar to what is found in simulations of convective self-aggregation. Radiative calculations show that clearsky radiative differences can explain a substantial part of this circulation, with further contributions expected from cloud radiative effects. The shallow component appears to be important for maintaining the low gross moist stability of the convecting column. A positive feedback between a shallow circulation driven by differential radiative cooling and the low-level moisture gradients that help support it is hypothesized to play an important role in conditioning the atmosphere for deep convection. The analysis suggests that the radiatively driven shallow circulations identified by modeling studies as contributing to the self-aggregation of convection in radiative-convective equilibrium similarly play a role in shaping the intertropical convergence zone and, hence, the large-scale structure of the tropical atmosphere. © 2018 American Meteorological Society."
"57196348092;6603779272;18437230800;7003311618;","Aerosol trends as a potential driver of regional climate in the central United States: Evidence from observations",2017,"10.5194/acp-17-13559-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034017636&doi=10.5194%2facp-17-13559-2017&partnerID=40&md5=6742dfe1070b099a1a2fffe7baa9782e","In situ surface observations show that downward surface solar radiation (SWdn) over the central and southeastern United States (US) has increased by 0.58-1.0Wm-2a-1 over the 2000-2014 time frame, simultaneously with reductions in US aerosol optical depth (AOD) of 3.3-5.0 × 10-3a-1. Establishing a link between these two trends, however, is challenging due to complex interactions between aerosols, clouds, and radiation. Here we investigate the clear-sky aerosol-radiation effects of decreasing US aerosols on SWdn and other surface variables by applying a one-dimensional radiative transfer to 2000-2014 measurements of AOD at two Surface Radiation Budget Network (SURFRAD) sites in the central and southeastern United States. Observations characterized as ""clear-sky"" may in fact include the effects of thin cirrus clouds, and we consider these effects by imposing satellite data from the Clouds and Earth's Radiant Energy System (CERES) into the radiative transfer model. The model predicts that 2000-2014 trends in aerosols may have driven clear-sky SWdn trends of +1.35Wm-2a-1 at Goodwin Creek, MS, and +0.93Wm-2a-1 at Bondville, IL. While these results are consistent in sign with observed trends, a cross-validated multivariate regression analysis shows that AOD reproduces 20-26% of the seasonal (June-September, JJAS) variability in clear-sky direct and diffuse SWdn at Bondville, IL, but none of the JJAS variability at Goodwin Creek, MS. Using in situ soil and surface flux measurements from the Ameriflux network and Illinois Climate Network (ICN) together with assimilated meteorology from the North American Land Data Assimilation System (NLDAS), we find that sunnier summers tend to coincide with increased surface air temperature and soil moisture deficits in the central US. The 1990-2015 trends in the NLDAS SWdn over the central US are also of a similar magnitude to our modeled 2000-2014 clear-sky trends. Taken together, these results suggest that climate and regional hydrology in the central US are sensitive to the recent reductions in aerosol concentrations. Our work has implications for severely polluted regions outside the US, where improvements in air quality due to reductions in the aerosol burden could inadvertently pose an enhanced climate risk. © Author(s) 2017."
"55322809700;6601961069;57190261615;57190245476;","A fast two-stream-like multiple-scattering method for atmospheric characterization and radiative transfer",2017,"10.1175/JAMC-D-17-0044.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026329161&doi=10.1175%2fJAMC-D-17-0044.1&partnerID=40&md5=94ea0a63ed3c8ce4d79dab9005f7fd8b","Multiple-scattering effects can significantly impact radiative transfer calculations for remote sensing and directed-energy applications. This study describes the development and implementation of a fast-calculating two-stream-like multiple-scattering algorithm that captures azimuthal and elevation variations into the Air Force Institute of Technology Center for Directed Energy's Laser Environmental Effects Definition and Reference (LEEDR) atmospheric characterization and radiative transfer code. LEEDR is a fast-calculating, first-principles, worldwide surface-to-100-km, atmospheric characterization package for the creation of vertical profiles of temperature, pressure, water vapor content, optical turbulence, atmospheric particulates, and hydrometeors as they relate to line-by-line layer transmission and radiance from the ultraviolet to radio frequencies. The newly implemented multiple-scattering algorithm fully solves for molecular, aerosol, cloud, and precipitation single-scatter layer effects with a Mie algorithm at every atmospheric layer. A unique set of asymmetry and backscattering phase-function parameter calculations accounts for radiance loss due to the molecular and aerosol constituent reflectivity within a layer and accurately characterize diffuse layers that contribute to multiple-scattered radiances in inhomogeneous atmospheres. LEEDR is valid for spectral bands between 200-nm and radio wavelengths. Accuracy is demonstrated by comparing LEEDR results with published sky radiance observations and experimental data. Determining accurate aerosol loading via an iterative visibility/particle-count calculation method is ultimately essential to achieve agreement between observations and model results for realistic atmospheres. © 2017 American Meteorological Society."
"56768490800;7006399667;57206204012;","Relationships between outgoing longwave radiation and diabatic heating in reanalyses",2017,"10.1007/s00382-016-3501-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007505785&doi=10.1007%2fs00382-016-3501-0&partnerID=40&md5=fc5f229eff9f5126d82441451bf9fa00","This study investigates relationships between daily variability in National Oceanographic and Atmospheric Administration (NOAA) outgoing longwave radiation (OLR), as a proxy for deep convection, and the global diabatic heat budget derived from reanalysis data sets. Results are evaluated based on data from ECMWF Reanalysis (ERA-Interim), Japanese 55-year Reanalysis (JRA-55) and Modern-Era Retrospective Analysis for Research and Applications (MERRA2). The diabatic heating is separated into components linked to ‘physics’ (mainly latent heat fluxes), plus longwave (LW) and shortwave (SW) radiative tendencies. Transient variability in deep convection is highly correlated with diabatic heating throughout the troposphere and stratosphere. Correlation patterns and composite analyses show that enhanced deep convection (lower OLR) is linked to amplified heating in the tropical troposphere and in the mid-latitude storm tracks, tied to latent heat release. Enhanced convection is also linked to radiative cooling in the lower stratosphere, due to weaker upwelling LW from lower altitudes. Enhanced transient deep convection increases LW and decreases SW radiation in the lower troposphere, with opposite effects in the mid to upper troposphere. The compensating effects in LW and SW radiation are largely linked to variations in cloud fraction and water content (vapor, liquid and ice). These radiative balances in reanalyses are in agreement with idealized calculations using a column radiative transfer model. The overall relationships between OLR and diabatic heating are robust among the different reanalyses, although there are differences in radiative tendencies in the tropics due to large differences of cloud water and ice content among the reanalyses. These calculations provide a simple statistical method to quantify variations in diabatic heating linked to transient deep convection in the climate system. © 2016, Springer-Verlag Berlin Heidelberg."
"57210687618;56375331500;7004247643;","Suppression of Arctic air formation with climate warming: Investigation with a two-dimensional cloud-resolving model",2017,"10.1175/JAS-D-16-0193.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029104750&doi=10.1175%2fJAS-D-16-0193.1&partnerID=40&md5=ab222b14eeb5a23798914fd901ef03f1","Arctic climate change in winter is tightly linked to changes in the strength of surface temperature inversions, which occur frequently in the present climate as Arctic air masses form during polar night. Recent work proposed that, in a warmer climate, increasing low-cloud optical thickness of maritime air advected over highlatitude landmasses during polar night could suppress the formation of Arctic air masses, amplifying winter warming over continents and sea ice. But this mechanism was based on single-column simulations that could not assess the role of fractional cloud cover change. This paper presents two-dimensional cloud-resolving model simulations that support the single-column model results: low-cloud optical thickness and duration increase strongly with initial air temperature, slowing the surface cooling rate as the climate is warmed. The cloud-resolving model cools less at the surface than the single-column model, and the sensitivity of its cooling to warmer initial temperatures is also higher, because it produces cloudier atmospheres with stronger lowertropospheric mixing and distributes cloud-top cooling over a deeper atmospheric layer with larger heat capacity. Resolving larger-scale cloud turbulence has the greatest impact on the microphysics schemes that best represent general observed features of mixed-phase clouds, increasing their sensitivity to climate warming. These findings support the hypothesis that increasing insulation of the high-latitude land surface by low clouds in a warmer world could act as a strong positive feedback in future climate change and suggest studying Arctic air formation in a three-dimensional climate model. © 2017 American Meteorological Society."
"56089348800;16475714800;","The physics of orographic elevated heating in radiative-convective equilibrium",2017,"10.1175/JAS-D-16-0312.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026291548&doi=10.1175%2fJAS-D-16-0312.1&partnerID=40&md5=2b33c63f5ea17e115afc0160d9d9d613","Elevated heating of the atmosphere by large plateaus has been argued to influence regional climate in Asia and other regions, but the mechanisms that cause the troposphere to equilibrate at warmer temperatures over elevated terrain are not well understood. This paper quantitatively describes the physics that controls temperatures over elevated terrain in radiative-convective equilibrium (RCE). First, a cloud-system-resolving model (CSRM) is used to simulate RCE states over surfaces with various elevations. Then, a theory for the influence of surface elevation on temperatures in RCE is presented. Together with offline radiative transfer calculations, this theory is used to quantitatively attribute the magnitude of the elevated heating effect to topof- atmosphere radiative flux changes caused by decreases in longwave absorption, shortwave scattering, and the moist lapse rate that occur as surface pressure drops. Sensitivity functions obtained through these offline calculations suggest that elevated heating is weaker in warmer climates, and additional CSRM simulations support this hypothesis. Under certain circumstances, even the sign of the elevated heating effect can change to produce cooler temperatures at a given pressure level as the surface is lifted in RCE. © 2017 American Meteorological Society."
"57033686900;56458012600;7202145115;","Low-cloud, boundary layer, and sea ice interactions over the Southern Ocean during winter",2017,"10.1175/JCLI-D-16-0483.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020131402&doi=10.1175%2fJCLI-D-16-0483.1&partnerID=40&md5=2c258cc73ec10c90fb5b97a0b7823422","During austral winter, a sharp contrast in low-cloud fraction and boundary layer structure across the Antarctic sea ice edge is seen in ship-based measurements and in active satellite retrievals from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), which provide an unprecedented view of polar clouds during winter. Sea ice inhibits heat and moisture transport from the ocean to the atmosphere, and, as a result, the boundary layer is cold, stable, and clear over sea ice and warm, moist, well mixed, and cloudy over open water. The mean low-cloud fraction observed by CALIPSO is roughly 0.7 over open water and 0.4-0.5 over sea ice, and the low-cloud layer is deeper over open water. Low-level winds in excess of 10 m s-1 are common over sea ice. Cold advection off of the sea ice pack causes enhanced low-cloud fraction over open water, and thus an enhanced longwave cloud radiative effect at the surface. Quantitative estimates of the surface longwave cloud radiative effect contributed by low clouds are presented. Finally, 10 state-of-the-art global climate models with satellite simulators are compared to observations. Near the sea ice edge, 7 out of 10 models simulate cloudier conditions over open water than over sea ice. Most models also underestimate low-cloud fraction both over sea ice and over open water. © 2017 American Meteorological Society."
"55713316500;7402146514;55601141900;35205101700;9240820800;","A New Method for Retrieving Daily Land Surface Albedo from VIIRS Data",2017,"10.1109/TGRS.2016.2632624","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017522273&doi=10.1109%2fTGRS.2016.2632624&partnerID=40&md5=6b5d1a76f60984dd6aaf2d79fca32ab0","Unlike instantaneous albedo, daily albedo of land surfaces is currently not routinely generated from satellite data, although it is a key input parameter for calculating daily shortwave radiation budget. This paper presents a novel approach to directly retrieve daily mean values of land surface broadband blue-sky albedo from Visible Infrared Imaging Radiometer Suite clear-sky data of apparent reflectance, with the assumption that the atmospheric conditions of the satellite overpass time can represent their daily values. Training data were simulated by atmospheric radiative transfer models, with surface spectra and bidirectional reflectance distribution function data as inputs for four aerosol types and a range of aerosol loadings. Sensitivity analysis was conducted to study the effects of cloud coverage, aerosol, and surface types on retrieval accuracy. Two years of measurements at six Surface Radiation Budget Network and eight Greenland Climate Network stations were used for algorithm validation. Daily albedo of snow-free surfaces can be retrieved with very high accuracy. By excluding far off-nadir observations of snow surfaces, the overall accuracy of retrieving daily albedo has a bias of 0.003 and a root-mean-square error of 0.055. © 1980-2012 IEEE."
"36753174700;35285676700;55337259400;7402711358;7006783796;7003475277;25029309200;26643481800;","Improved modeling of cloudy-sky actinic flux using satellite cloud retrievals",2017,"10.1002/2016GL071892","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012107892&doi=10.1002%2f2016GL071892&partnerID=40&md5=6b9908ac916a65de98d8b2b9a00c63d0","Clouds play a critical role in modulating tropospheric radiation and thus photochemistry. We develop a methodology for calculating the vertical distribution of tropospheric ultraviolet (300–420 nm) actinic fluxes using satellite cloud retrievals and a radiative transfer model. We demonstrate that our approach can accurately reproduce airborne-measured actinic fluxes from the 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign as a case study. The results show that the actinic flux is reduced below moderately thick clouds with increasing cloud optical depth and can be enhanced by a factor of 2 above clouds. Inside clouds, the actinic flux can be enhanced by up to 2.4 times in the upper part of clouds or reduced up to 10 times in the lower parts of clouds. Our study suggests that the use of satellite-derived actinic fluxes as input to chemistry-transport models can improve the accuracy of photochemistry calculations. ©2017. The Authors."
"6602360081;24536795200;57193085141;","Downward solar global irradiance at the surface in São Paulo city-The climatological effects of aerosol and clouds",2017,"10.1002/2016JD025585","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010665751&doi=10.1002%2f2016JD025585&partnerID=40&md5=08f19d5e10f13fa85370d6c081877f61","We analyzed the variability of downward solar irradiance reaching the surface at São Paulo city, Brazil, and estimated the climatological aerosol and cloud radiative effects. Eleven years of irradiance were analyzed, from 2005 to 2015. To distinguish the aerosol from the cloud effect, the radiative transfer code LibRadtran was used to calculate downward solar irradiance. Two runs were performed, one considering only ozone and water vapor daily variability, with AOD set to zero and the second allowing the three variables to change, according to mean climatological values. The difference of the 24 h mean irradiance calculated with and without aerosol resulted in the shortwave aerosol direct radiative effect, while the difference between the measured and calculated, including the aerosol, represented the cloud effect. Results showed that, climatologically, clouds can be 4 times more effective than aerosols. The cloud shortwave radiative effect presented a maximum reduction of about -170Wm-2 in January and a minimum in July, of -37Wm-2. The aerosol direct radiative effect was maximum in spring, when the transport of smoke from the Amazon and central parts of South America is frequent toward São Paulo. Around mid-September, the 24 h radiative effect due to aerosol only was estimated to be -50Wm-2. Throughout the rest of the year, the mean aerosol effect was around -20Wm-2 and was attributed to local urban sources. The effect of the cloud fraction on the cloud modification factor, defined as the ratio of all-sky irradiation to cloudless sky irradiation, showed dependence on the cloud height. Low clouds presented the highest impact while the presence of high clouds only almost did not affect solar transmittance, even in overcast conditions. © 2016. American Geophysical Union. All Rights Reserved."
"56206456800;57191221599;8383395800;6504688501;57191980050;9736951600;7004402705;35547807400;7005211669;","Atmospheric lifetimes, infrared absorption spectra, radiative forcings and global warming potentials of NF3 and CF3CF2Cl (CFC-115)",2016,"10.5194/acp-16-11451-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988354966&doi=10.5194%2facp-16-11451-2016&partnerID=40&md5=9f1fcd3ad0947db4c1a2dd83e97279f3","Fluorinated compounds such as NF3 and C2F5Cl (CFC-115) are characterised by very large global warming potentials (GWPs), which result from extremely long atmospheric lifetimes and strong infrared absorptions in the atmospheric window. In this study we have experimentally determined the infrared absorption cross sections of NF3 and CFC-115, calculated the radiative forcing and efficiency using two radiative transfer models and identified the effect of clouds and stratospheric adjustment. The infrared cross sections are within 10% of previous measurements for CFC-115 but are found to be somewhat larger than previous estimates for NF3, leading to a radiative efficiency for NF3 that is 25% larger than that quoted in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A whole atmosphere chemistry-climate model was used to determine the atmospheric lifetimes of NF3 and CFC-115 to be (509±21) years and (492±22) years, respectively. The GWPs for NF3 are estimated to be 15 600, 19 700 and 19 700 over 20, 100 and 500 years, respectively. Similarly, the GWPs for CFC-115 are 6030, 7570 and 7480 over 20, 100 and 500 years, respectively. © 2016 Author(s)."
"56536745100;36141355100;57203053317;7003748648;","The resolution dependence of cloud effects and ship-induced aerosol-cloud interactions in marine stratocumulus",2016,"10.1002/2015JD024685","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966344397&doi=10.1002%2f2015JD024685&partnerID=40&md5=d5a05fe26449b489be2a47984b0b0e0d","Measures of aerosol-cloud interactions in stratocumulus have been shown to depend on the resolution of the applied data set. In order to contrast resolution with emission dilution effects in models, a regional numerical weather prediction model is used to simulate ship tracks at a range of spatiotemporal resolutions ranging from the global climate modeling scale (Δx = 50 km, Δt = 180 s) to the convection-resolving scale (Δx = 1 km, Δt = 20 s). The background simulations without ship emissions display a high degree of similarity in the planetary boundary layer and cloud properties at all spatiotemporal resolutions. Simulations assessing the impact of emission dilution show an increasing overestimation of the shortwave (SW) cloud radiative effect (CRE) with degenerating emission resolution. Although mean perturbations in the activation-sized aerosol number concentration (Nact) are similar for all dilution experiments, the variability in Nact is increasingly lost with stronger emission dilution. The enhanced Nact homogeneity in turn leads to an overestimated SW CRE. We show that emission dilution alone accounts for 47% of the overestimated SW CRE simulated at low resolutions. The remainder of the differences is attributed to a combination of locally enhanced aerosol concentrations due to weaker vertical mixing simulated at coarse resolutions, in combination with a faster conversion rate of Aitken to accumulation mode particles by redistribution in these regions. © 2016. American Geophysical Union. All rights reserved."
"56829579700;14019399400;55740664200;56829592600;","A one-year study of the diurnal cycle of meteorology, clouds and radiation in the West African Sahel region",2016,"10.1002/qj.2623","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957849466&doi=10.1002%2fqj.2623&partnerID=40&md5=a0d388ccd1f72f200ff823ee65046406","The diurnal cycles of meteorological and radiation variables are analysed during the wet and dry seasons over the Sahel region of West Africa during 2006 using surface data collected by the Atmospheric Radiation Measurement (ARM) programme's Mobile Facility, satellite radiation measurements from the Geostationary Earth Radiation Budget (GERB) instrument aboard Meteosat 8, and reanalysis products from the National Centers for Environmental Prediction (NCEP). The meteorological analysis builds upon past studies of the diurnal cycle in the region by incorporating diurnal cycles of lower tropospheric wind profiles, thermodynamic profiles, integrated water vapour and liquid water measurements, and cloud radar measurements of frequency and location. These meteorological measurements are complemented by 3 h measurements of the diurnal cycles of the top-of-atmosphere (TOA) and surface short-wave (SW) and long-wave (LW) radiative fluxes and cloud radiative effects (CREs), and the atmospheric radiative flux divergence (RFD) and atmospheric CREs. Cirrus cloudiness during the dry season is shown to peak in coverage in the afternoon, while convective clouds during the wet season are shown to peak near dawn and have an afternoon minimum related to the rise of the lifting condensation level into the Saharan Air Layer. The LW and SW RFDs and CREs exhibit diurnal cycles during both seasons, but there is a relatively small difference in the LW cycles during the two seasons (10 - 30 W m-2 depending on the variable and time of day). Small differences in the TOA CREs during the two seasons are overwhelmed by large differences in the surface SW CREs, which exceed 100 W m-2. A significant surface SW CRE during the wet season combined with a negligible TOA SW CRE produces a diurnal cycle in the atmospheric CRE that is modulated primarily by the SW surface CRE, peaks at midday at ∼150 W m-2, and varies widely from day to day. © 2016 Royal Meteorological Society."
"7410070663;25941200000;7403931916;48661551300;","On the aerosol and cloud phase function expansion moments for radiative transfer simulations",2015,"10.1002/2015JD023632","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958768017&doi=10.1002%2f2015JD023632&partnerID=40&md5=e64a79b3bc64522ebd46763b3a4cdef1","The accuracy of the Henyey-Greenstein (HG) approximation in radiative transfer process is systematically investigated for aerosol and cloud particles. For small-size aerosols, the phase function moment by the HG approximation is close to that of the true phase function; therefore, the differences in four-stream radiative transfer calculations are very small whether using the HG approximation or the true phase function moments. However, for large-size aerosols, liquid cloud droplets and ice crystals, the HG approximation produces very different phase function moment result compared to the true phase function. In case of small optical depth, the single layer four-stream radiative transfer calculations show that the HG approximation can produce relative errors larger than 20% while the errors are generally less than 5% by using true phase function moments. By applying the four-stream radiative transfer scheme to a multilayer atmosphere with aerosol and cloud, the differences in flux error are generally less than 2 Wm−2 by using either the HG approximation or true phase function moments, but can be over 10 Wm−2 for ice cloud case. The aerosol/cloud instantaneous radiative forcing has been analyzed in climate simulation. Compared to the four-stream radiative transfer scheme, the two-stream radiative transfer scheme overestimates the aerosol radiative flux in low-latitude regions and underestimates the upward flux for the high-latitude regions. By using the HG approximation, the difference in aerosol radiative forcing between the four-stream and the two-stream radiative transfer schemes is enhanced; the enhancement can be up to 0.5 Wm−2. The parameterization schemes for aerosol and cloud optical properties must be extended to contain higher-order phase function moments, if higher-order stream radiative transfer algorithms are to be used. © 2015. American Geophysical Union. All rights reserved."
"56489062200;7404653593;36815705700;12040335900;","Retrieval of outgoing longwave radiation from COMS narrowband infrared imagery",2015,"10.1007/s00376-014-4013-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84938299751&doi=10.1007%2fs00376-014-4013-7&partnerID=40&md5=264abfaa86613ca6f324e08ec27011d2","Hourly outgoing longwave radiation (OLR) from the geostationary satellite Communication Oceanography Meteorological Satellite (COMS) has been retrieved since June 2010. The COMS OLR retrieval algorithms are based on regression analyses of radiative transfer simulations for spectral functions of COMS infrared channels. This study documents the accuracies of OLRs for future climate applications by making an intercomparison of four OLRs from one single-channel algorithm (OLR
It is shown that the CWP retrievals are very sensitive to the assumptions made in the CPP code. The CWP retrieval errors are generally small for unbroken single-layer clouds with COT > 10, with retrieval errors of ∼3% for liquid water clouds to ∼10% for ice clouds. In a multi-layer cloud, when both liquid water and ice clouds are present in a pixel, the CWP retrieval errors increase dramatically; depending on the cloud, this can lead to uncertainties of 40-80%. CWP retrievals also become more uncertain when the cloud does not cover the entire pixel, leading to errors of ∼50% for cloud fractions of 0.75 and even larger errors for smaller cloud fractions. Thus, the satellite retrieval of cloud physical properties of broken clouds as well as multi-layer clouds is complicated by inherent difficulties, and the proper interpretation of such retrievals requires extra care. © Author(s) 2012. CC Attribution 3.0 License."
"15032788000;57196263581;36866507800;8832722300;","Mammatus clouds as a response to cloud-base radiative heating",2010,"10.1175/2010JAS3513.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78651088579&doi=10.1175%2f2010JAS3513.1&partnerID=40&md5=90a9fc6e548f8a99fe56be0281f6f8f3","Mammatus clouds are the pouchlike lobes seen hanging from mid- to high-level clouds. They can look quite dramatic, but they are also interesting because they provide clues to what controls anvil cirrus dynamic evolution. Thus far, the most commonly accepted explanation for observed subsidence of mammatus lobes is that they are driven by evaporative cooling of precipitation, accelerated by mixing with dry subcloud air. Here, an alternative explanation is proposed: radiative temperature contrasts between cloud base and the lower troposphere destabilize cloudy air to create a rapidly deepening mixed layer, which creates positively buoyant intrusions of dry air into the cloud interior; mammatus lobes are just the descending branch of the resulting circulations. In this regard, mammatus cloud fields might be considered an upside-down analog to the radiatively driven formation of ""cloud holes"" seen at the tops of stratocumulus layers. © 2010 American Meteorological Society."
"35746258100;7003922583;57200684699;56917398600;","Parameterization of solar radiation from model and observations",2010,"10.1127/0941-2948/2010/0423","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949466142&doi=10.1127%2f0941-2948%2f2010%2f0423&partnerID=40&md5=fe64b59c842e76b99b3a266141d2ef38","The influence of the external and internal structure of clouds on the incoming solar radiation cannot yet be included in parameterizations used in numerical models. Based on numerical simulations, SCHEWSKI and MACKE (2003) (Schewski-parameterization) have shown that a robust link exists between the domain averaged cloud and the domain averaged solar broadband radiation fluxes, despite the 3d nature of the cloud fields involved. The present work revisits this approach with observed cloud (cloud cover and liquid water path) and radiation (downwelling shortwave radiative flux) properties obtained from the Richard Assmann Observatory (RAO) of the German Weather Service in Lindenberg. Applying the original (model based) cloud-radiation parameterization by SCHEWSKI and MACKE (2001) to observed domain averaged cloud fields yields an overall good correlation between observed and parameterized downwelling solar radiation fluxes. However, the parameterized fluxes strongly underestimate the observations. The Schewski parameterization has been modified by removing the bias and re-adjusting the parameterization coefficients to match the observed cloud and radiation correlation. Furthermore, the empirical parameterization by ZILLMAN (1972) has been implemented for describing the clear conditions. Applying the new parameterization to an independent data set provides significant improvements. However, the accuracy remains in the order of previously used one- or two-parameter empirical cloud-radiation parameterizations. We conclude that cloud cover and liquid water path, i.e. those data that are available from large scale climate models, cannot be regarded as sufficient to describe the cloud radiative effect at the surface. © 2010 Gebrüder Borntraeger, Berlin, Stuttgart."
"23048575400;7005174340;6603382350;7103204204;57203405965;7202245296;6603800142;23990280900;7006813055;7003729315;57214160655;7403682442;","A new method to retrieve the aerosol layer absorption coefficient from airborne flux density and actinic radiation measurements",2010,"10.1029/2009JD013636","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955390982&doi=10.1029%2f2009JD013636&partnerID=40&md5=362bb4cf29a78e8a99656054ee96f10b","A new method is presented to derive the mean value of the spectral absorption coefficient of an aerosol layer from combined airborne measurements of spectral net irradiance and actinic flux density. While the method is based on a theoretical relationship of radiative transfer theory, it is applied to atmospheric radiation measurements for the first time. The data have been collected with the Spectral Modular Airborne Radiation Measurement System (SMART-Albedometer), the Solar Spectral Flux Radiometer (SSFR), and the Actinic Flux Spectroradiometer (AFSR) during four field campaigns between 2002 and 2008 (the Saharan Mineral Dust Experiment (SAMUM), the Influence of Clouds on the Spectral Actinic Flux in the Lower Troposphere (INSPECTRO) project, and the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites and Aerosol, Radiation, and Cloud Processes Affecting Arctic Climate (ARCTAS/ARCPAC) projects). The retrieval algorithm is tested in a series of radiative transfer model runs and then applied to measurement cases with different aerosol species and loading. The method is shown to be a feasible approach to obtain the mean aerosol absorption coefficient across a given accessible altitude range. The results indicate that the method is viable whenever the difference of the net irradiance at the top and bottom of a layer is equal to or higher than the measurement uncertainty for net irradiance. This can be achieved by a high optical depth or a low single-scattering albedo within the layer. Copyright 2010 by the American Geophysical Union."
"7005485117;14047829400;","Transitions in the surface energy balance dufring the life cycle of a monsoon season",2006,"10.1007/BF02702033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746323920&doi=10.1007%2fBF02702033&partnerID=40&md5=2a5ba0ed5dbea03f87e6fae4954bbf6b","In this observational/diagnostic study, we illustrate the time history of some important parameters of the surface energy balance during the life cycle of a single monsoon season. This chronology of the surface energy balance portrays the differential equilibrium state from the preonset phase to the withdrawal phase. This includes an analysis of the time history of base variables such as soil moisture, ground temperature, cloud cover, precipitation and humidity. This is followed by an analysis of the components of the surface energy balance where we note subtle changes in the overall balances as we proceed from one epoch of the monsoon to the next. Of interest here is the transition sequence: preonset, onset, break, revival, break, revival and withdrawal during the year 2001. Computations are all illustrated for a box over central India where the coastal effects were small, data coverage was not sparse and where the semi-arid land mass changes drastically to a lush green area. This region exhibited large changes in the components of surface energy balance. The principal results pertain to what balances the difference among the incoming short wave radiation (at the earth's surface) and the long wave radiation exhibited by the ground. That difference is balanced by a dominant sensible heat flux and the reflected short wave radiation in the preonset stage. A sudden change in the Bowen ratio going from > 1 to < 1 is noted soon after the onset of monsoon. Thereafter the latent heat flux from the land surface takes an important role and the sensible heat flux acquires a diminishing role. We also examine the subtle changes that occur in the components of surface energy balance between the break and the active phases. The break phases are seen to be quite different from the preonset phases. This study is aimed to illustrate the major importance of moisture and clouds in the radiative transfer computations that are central to the surface energy balance during each epoch. These sensitivities (of moisture and clouds) have major consequences for weather and climate forecasts. © Printed in India."
"57203773116;37023776800;14032593100;7501513440;","Analysis of temporal variability of MODIS Leaf Area Index (LAI) product over temperate forest in Korea",2005,"10.1109/IGARSS.2005.1525880","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745712236&doi=10.1109%2fIGARSS.2005.1525880&partnerID=40&md5=b3f44c15bb262c405bb7cd7e491ced87","MODIS LAI product is very important because it has potential for the monitoring of global scale ecosystem, global change of carbon and water. This study aims to analyze the temporal variability of annual MODIS LAI product using field measured LAI dataset for four vegetation types. The MODIS annual LAI pattern shows the high variety or inaccuracy of LAI during rainy season over South Korea. This phenomenon is caused by high cloud coverage and fails of processing by a radiative transfer model in this rainy season. Annual LAI pattern estimated by a radiative transfer model has least variance of LAI values during this time. In coniferous forest, MODIS annual LAI pattern shows the abnormal decreasing of LAI during nongrowing season comparing with field-measured LAI. This decrease of LAI being an inaccurate phenomenon is caused by rather higher cloud coverage and decreasing of understory plants. MODIS LAI product in deciduous and grass coverage is underestimated by comparing with field-measured LAI. In rice paddy, MODIS LAI shows longer growing season than field measured LAI. For the accurate analysis of temporal MODIS LAI product, it needs considering of vegetation coverage types, cloud coverage, and algorithm types of MODIS LAI. © 2005 IEEE."
"6603800142;56210166100;7005030033;","An overview of the disposition of solar radiation in the lower atmosphere: Connections to the SORCE mission and climate change",2005,"10.1007/s11207-005-2379-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-28444474528&doi=10.1007%2fs11207-005-2379-5&partnerID=40&md5=2aee3398352897a5de082c4adb639756","Solar radiation is the primary energy source for many processes in Earth's environment and is responsible for driving the atmospheric and oceanic circulation. The integrated strength and spectral distribution of solar radiation is modified from the space-based {Solar {Radiation and {Climate (SORCE) measurements through scattering and absorption processes in the atmosphere and at the surface. Understanding how these processes perturb the distribution of radiative flux density is essential in determining the climate response to changes in concentration of various gases and aerosol particles from natural and anthropogenic sources, as is discerning their associated feedback mechanisms. The past decade has been witness to a tremendous effort to quantify the absorption of solar radiation by clouds and aerosol particles via airborne and space-based observations. Vastly improved measurement and modeling capabilities have enhanced our ability to quantify the radiative energy budget, yet gaps persist in our knowledge of some fundamental variables. This paper reviews some of the many advances in atmospheric solar radiative transfer as well as those areas where large uncertainties remain. The SORCE mission's primary contribution to the energy budget studies is the specification of the solar total and spectral irradiance at the top of the atmosphere. © Springer 2005."
"6603081424;7201844203;6701346974;25941200000;7003398947;","Performance of Goddard earth observing system GCM column radiation models under heterogeneous cloud conditions",2004,"10.1016/j.atmosres.2004.03.025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-8644277057&doi=10.1016%2fj.atmosres.2004.03.025&partnerID=40&md5=1a7e74ff1d9b48b207f9f31b4d9a741d","We test the performance of the shortwave (SW) and longwave (LW) Column Radiation Models (CORAMs) of Chou and collaborators with heterogeneous cloud fields from a single-day global dataset produced by NCAR's Community Atmospheric Model (CAM) with a 2-D Cloud Resolving Model (CRM) installed in each column. The original SW version of the CORAM performs quite well compared to reference Independent Column Approximation (ICA) calculations for boundary fluxes (global error ∼4 W m-2 for reflected flux), largely due to the success of a combined overlap and cloud scaling parameterization scheme. The absolute magnitude of errors relative to ICA are even smaller (global error ∼2 W m-2 for outgoing flux) for the LW CORAM which applies similar overlap. The vertical distribution of heating and cooling within the atmosphere is also simulated quite well with daily averaged zonal errors always less than 0.3 K/day for SW and 0.6 K/day for LW heating (cooling) rates. The SW CORAM's performance improves by introducing a scheme that accounts for cloud inhomogeneity based on the Gamma Weighted Two Stream Approximation (GWTSA). These results suggest that previous studies demonstrating the inaccuracy of plane-parallel models may have unfairly focused on worst case scenarios, and that current radiative transfer algorithms in General Circulation Models (GCMs) may be more capable than previously thought in estimating realistic spatial and temporal averages of radiative fluxes, as long as they are provided with correct mean cloud profiles. However, even if the errors of our particular CORAMs are small, they seem to be systematic, and their impact can be fully assessed only with GCM climate simulations. © 2004 Elsevier B.V. All rights reserved."
"7202928981;7101833247;","The accuracy of downward short- and long-wave radiation at the earth's surface calculated using simple models",2004,"10.1017/S1350482703001154","https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942579003&doi=10.1017%2fS1350482703001154&partnerID=40&md5=290210bf67421a73bf170daeeb90c8db","Estimates of the downward global solar and long-wave radiations are commonly made using simple models. We have tested the estimates produced by a number of these simple models against the values predicted by the radiative transfer model used in a climate model in order to determine their suitability for global applications. For clear sky, two simple models were comparable, but under cloudy conditions a combination of a clear-sky model based on the Angstrom-Prescott equation (which deals with the downwelling solar radiation) with a cloud transmissivity utilising total cloud fraction proved best. The lowest root mean square errors were 27 W m-2 for clear-sky global solar radiation and 90 W m-2 for cloudy conditions. For downward long-wave radiation in clear-sky conditions, the model of Garratt (1992) performed best with a root mean square error of 24 W m-2. However, in cloudy conditions the model of Idso & Jackson (1969) performed best with a root mean square error of 22 W m-2, and, as it performs nearly as well as that of Garratt (1992) in clear-sky conditions, it is probably the best choice."
"55547130346;7007010459;","A comparison of climate forcings due to chlorofluorocarbons and carbon monoxide",1996,"10.1029/95GL03593","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029749958&doi=10.1029%2f95GL03593&partnerID=40&md5=84a1dd669b77c78803c72d202122fc9e","The direct radiative forcing of climate by carbon monoxide (CO) is generally considered to be negligible. However, a recent study of localised clear-sky surface irradiances asserts that the forcing by CO may be comparable to that by CFC-11. Nevertheless no detailed comparison of CO and CFC climate forcings has yet been made. Thus the present study estimates the radiative impact of the increases in CO, CFC-11 and CFC-12 that have occurred since industrialisation. A radiative transfer model is used to reproduce the results of the earlier study. Clouds are then added, and the stratosphere-adjusted forcing at the tropopause (the ""climate forcing"") calculated. Global-mean anthropogenic climate forcing by CO is determined to be 32% of that by CFC-11, 12% of that by CFC-12, and 9% of that by the CFCs combined. Even if the contemporary global-mean CO concentration is increased by a factor of three, the climate forcing by CO is still only 75% of that due to CFC-11. Regarding instantaneous clearsky forcings, further analysis shows that surface measurements can give a misleading impression of effects at the tropopause. While the indirect effects of CO on climate change are not yet properly quantified, the direct radiative effects appear, as previously thought, to be of only minor significance."
"7201784177;","Mechanisms of Future Predicted Changes in the Zonal Mean Mid-Latitude Circulation",2019,"10.1007/s40641-019-00145-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075353159&doi=10.1007%2fs40641-019-00145-8&partnerID=40&md5=5a93409b64278f25acf3c101937aaf90","State-of-the-art climate models predict the zonal mean mid-latitude circulation will undergo a poleward shift and seasonally and hemispherically dependent intensity changes in the future. Here I review the mechanisms put forward to explain the zonal mean mid-latitude circulation response to increased carbon dioxide (CO2) concentration. The mechanisms are grouped according to their thermodynamic starting point, which are thought to arise from processes independent of the zonal mean mid-latitude circulation response. There are 24 mechanisms and 8 thermodynamic starting points: (i) increased latent heat release aloft in the tropics, (ii) increased dry static stability and tropopause height outside the tropics, (iii) radiative cooling of the stratosphere, (iv) Hadley cell expansion, (v) increased specific humidity following the Clausius-Clapeyron relation, (vi) cloud radiative effect changes, (vii) turbulent surface heat flux changes, and (viii) decreased surface meridional temperature gradient. I argue progress can be made by testing the thermodynamic starting points. I review recent tests of the increased latent heat release aloft in the tropics starting point, i.e., prescribing diabatic perturbations, quantifying the transient response to an abrupt CO2 increase and imposing latitudinally dependent CO2 concentration. Finally, I provide a future outlook for improving our understanding of predicted changes in the zonal mean mid-latitude circulation. © 2019, The Author(s)."
"56537463000;22959252400;7404829395;56127418900;7006417494;7005973015;","A dichotomy between model responses of tropical ascent and descent to surface warming",2019,"10.1038/s41612-019-0066-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071331589&doi=10.1038%2fs41612-019-0066-8&partnerID=40&md5=dcadc0ee30051ff35d2dd0d8043263d1","Simulations of tropical atmospheric circulation response to surface warming vary substantially across models, causing large uncertainties in projections of regional precipitation change. Understanding the physical processes that drive the model spread in tropical circulation changes is critically needed. Here we employ the basic mass balance and energetic constraints on tropical circulation to identify the dominant factors that determine multidecadal circulation strength and area changes in climate models. We show that the models produce a robust weakening of descent rate under warming regardless of surface warming patterns; however, ascent rate change exhibits inter-model spread twice as large as descent rate because of diverse model responses in the radiative effects of clouds, water vapor, and aerosols. As ascent area change is dictated by the disparate descent and ascent rate changes due to the mass budget and the inter-model spread in descent rate change is small, the model spread in ascent area change is dominated by that of ascent rate change, resulting in a strong anti-correlation of –0.85 between the fractional changes of ascent strength and area across 77 climate model simulations. This anti-correlation leads to a corresponding inverse relationship between the rates of precipitation intensifying and narrowing of the inter-tropical convergence zone (ITCZ), suggesting tropical ascent area change can be potentially used to constrain the ITCZ precipitation change. Longwave cloud radiative effect at the top-of-atmosphere (TOA) in the convective region is identified to be a major source of uncertainties for tropical ascent rate change and thus for regional precipitation change. © 2019, The Author(s)."
"57204513348;57194102284;57195672525;57211314316;57211324913;15923105200;7005428785;","Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals",2019,"10.5194/acp-19-12397-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073470280&doi=10.5194%2facp-19-12397-2019&partnerID=40&md5=c52ec67de05668fee36baeae126662fd","An organic aerosol particle has a lifetime of approximately 1 week in the atmosphere during which it will be exposed to sunlight. However, the effect of photochemistry on the propensity of organic matter to participate in the initial cloud-forming steps is difficult to predict. In this study, we quantify on a molecular scale the effect of photochemical exposure of naturally occurring dissolved organic matter (DOM) and of a fulvic acid standard on its cloud condensation nuclei (CCN) and ice nucleation (IN) activity. We find that photochemical processing, equivalent to 4.6 d in the atmosphere, of DOM increases its ability to form cloud droplets by up to a factor of 2.5 but decreases its ability to form ice crystals at a loss rate of-0:04 °CT50 h-1 of sunlight at ground level. In other words, the ice nucleation activity of photooxidized DOM can require up to 4 °C colder temperatures for 50% of the droplets to activate as ice crystals under immersion freezing conditions. This temperature change could impact the ratio of ice to water droplets within a mixed-phase cloud by delaying the onset of glaciation and by increasing the supercooled liquid fraction of the cloud, thereby modifying the radiative properties and the lifetime of the cloud. Concurrently, a photomineralization mechanism was quantified by monitoring the loss of organic carbon and the simultaneous production of organic acids, such as formic, acetic, oxalic and pyruvic acids, CO and CO2. This mechanism explains and predicts the observed increase in CCN and decrease in IN efficiencies. Indeed, we show that photochemical processing can be a dominant atmospheric ageing process, impacting CCN and IN efficiencies and concentrations. Photomineralization can thus alter the aerosol-cloud radiative effects of organic matter by modifying the supercooled-liquid-water-to-ice-crystal ratio in mixed-phase clouds with implications for cloud lifetime, precipitation patterns and the hydrological cycle. Highlights. During atmospheric transport, dissolved organic matter (DOM) within aqueous aerosols undergoes photochemistry. We find that photochemical processing of DOM increases its ability to form cloud droplets but decreases its ability to form ice crystals over a simulated 4.6 d in the atmosphere. A photomineralization mechanism involving the loss of organic carbon and the production of organic acids, CO and CO2 explains the observed changes and affects the liquid-water-to-ice ratio in clouds. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License."
"6701606453;57211757871;57002856000;7410041005;","Reassessing the effect of cloud type on earth's energy balance in the age of active spaceborne observations. Part I: Top of atmosphere and surface",2019,"10.1175/JCLI-D-18-0753.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072597929&doi=10.1175%2fJCLI-D-18-0753.1&partnerID=40&md5=d57dd328adfa882f19eea97b0417c9b5","This study revisits the classical problem of quantifying the radiative effects of unique cloud types in the era of spaceborne active observations. The radiative effects of nine cloud types, distinguished based on their vertical structure defined by CloudSat and CALIPSO observations, are assessed at both the top of the atmosphere and the surface. The contributions from single- and multilayered clouds are explicitly diagnosed. The global, annual mean net cloud radiative effect at the top of the atmosphere is found to be 217.1 ± 4.-Wm-2 owing to 244.2 6 -Wm-2 of shortwave cooling and 27.1 ± 3.7Wm-2 of longwave heating. Leveraging explicit cloud base and vertical structure information, we further estimate the annual mean net cloud radiative effect at the surface to be224.868.7Wm-2 (251.167.8Wm-2 in the shortwave and 26.3 plusmn; 3.8Wm-2 in the longwave). Multilayered clouds are found to exert the strongest influence on the top-ofatmosphere energy balance. However, a strong asymmetry in net cloud radiative cooling between the hemispheres (8.6Wm-2) is dominated by enhanced cooling from stratocumulus over the southern oceans. It is found that there is no corresponding asymmetry at the surface owing to enhanced longwave emission by southern ocean clouds in winter, which offsets a substantial fraction of their impact on solar absorption in summer. Thus the asymmetry in cloud radiative effects is entirely realized as an atmosphere heating imbalance between the hemispheres. © 2019 American Meteorological Society."
"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."
"7102953444;55224074800;6602809597;57203656881;7003748648;56493740900;7402480218;","The cloud-free global energy balance and inferred cloud radiative effects: an assessment based on direct observations and climate models",2019,"10.1007/s00382-018-4413-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052554702&doi=10.1007%2fs00382-018-4413-y&partnerID=40&md5=b3f82fead9319a24a0e7fb88eaf44d9f","In recent studies we quantified the global mean Earth energy balance based on direct observations from surface and space. Here we infer complementary reference estimates for its components specifically under cloud-free conditions. While the clear-sky fluxes at the top of atmosphere (TOA) are accurately known from satellite measurements, the corresponding fluxes at the Earth’s surface are not equally well established, as they cannot be directly measured from space. This is also evident in 38 global climate models from CMIP5, which are shown to greatly vary in their clear-sky surface radiation budgets. To better constrain the latter, we established new clear-sky reference climatologies of surface downward shortwave and longwave radiative fluxes from worldwide distributed Baseline Surface Radiation Network sites. 33 out of the 38 CMIP5 models overestimate the clear-sky downward shortwave reference climatologies, whereas both substantial overestimations and underestimations are found in the longwave counterparts in some of the models. From the bias structure of the CMIP5 models we infer best estimates for the global mean surface downward clear-sky shortwave and longwave radiation, at 247 and 314 Wm −2 , respectively. With a global mean surface albedo of 13.5% and net shortwave clear-sky flux of 287 Wm −2 at the TOA this results in a global mean clear-sky surface and atmospheric shortwave absorption of 214 and 73 Wm −2 , respectively. From the newly-established diagrams of the global energy balance under clear-sky and all-sky conditions, we quantify the cloud radiative effects not only at the TOA, but also within the atmosphere and at the surface. © 2018, The Author(s)."
"57194799517;6603925960;57190852346;7003663305;57207507108;57203078745;7003440089;57203030873;57193321831;8397494800;","How well are clouds simulated over Greenland in climate models? Consequences for the surface cloud radiative effect over the ice sheet",2018,"10.1175/JCLI-D-18-0023.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056097399&doi=10.1175%2fJCLI-D-18-0023.1&partnerID=40&md5=f1633cefa871fc1d686cd4e56d7c7979","Using lidar and radiative flux observations from space and ground, and a lidar simulator, we evaluate clouds simulated by climate models over the Greenland ice sheet, including predicted cloud cover, cloud fraction profile, cloud opacity, and surface cloud radiative effects. The representation of clouds over Greenland is a central concern for the models because clouds impact ice sheet surface melt. We find that over Greenland, most of the models have insufficient cloud cover during summer. In addition, all models create too few nonopaque, liquid-containing clouds optically thin enough to let direct solar radiation reach the surface (-1% to -3.5% at the ground level). Some models create too few opaque clouds. In most climate models, the cloud properties biases identified over all Greenland also apply at Summit, Greenland, proving the value of the ground observatory in model evaluation. At Summit, climate models underestimate cloud radiative effect (CRE) at the surface, especially in summer. The primary driver of the summer CRE biases compared to observations is the underestimation of the cloud cover in summer (-46% to -21%), which leads to an underestimated longwave radiative warming effect (CRELW = -35.7 to -13.6 W m-2 compared to the ground observations) and an underestimated shortwave cooling effect (CRESW = +1.5 to +10.5 W m-2 compared to the ground observations). Overall, the simulated clouds do not radiatively warm the surface as much as observed. © 2018 American Meteorological Society."
"36822103700;57203102974;25230018900;7006107059;7102944401;","A satellite-based estimate of combustion aerosol cloud microphysical effects over the Arctic Ocean",2018,"10.5194/acp-18-14949-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055311978&doi=10.5194%2facp-18-14949-2018&partnerID=40&md5=a3a066463ba2515340f356824ff71964","Climate predictions for the rapidly changing Arctic are highly uncertain, largely due to a poor understanding of the processes driving cloud properties. In particular, cloud fraction (CF) and cloud phase (CP) have major impacts on energy budgets, but are poorly represented in most models, often because of uncertainties in aerosol-cloud interactions. Here, we use over 10 million satellite observations coupled with aerosol transport model simulations to quantify large-scale microphysical effects of aerosols on CF and CP over the Arctic Ocean during polar night, when direct and semi-direct aerosol effects are minimal. Combustion aerosols over sea ice are associated with very large (∼ 10Wmg-2) differences in longwave cloud radiative effects at the sea ice surface. However, co-varying meteorological changes on factors such as CF likely explain the majority of this signal. For example, combustion aerosols explain at most 40% of the CF differences between the full dataset and the clean-condition subset, compared to between 57% and 91% of the differences that can be predicted by co-varying meteorology. After normalizing for meteorological regime, aerosol microphysical effects have small but significant impacts on CF, CP, and precipitation frequency on an Arctic-wide scale. These effects indicate that dominant aerosol-cloud microphysical mechanisms are related to the relative fraction of liquid-containing clouds, with implications for a warming Arctic. © Author(s) 2018."
"57203690602;8708213500;","Wind shear effects on radiatively and evaporatively driven stratocumulus tops",2018,"10.1175/JAS-D-18-0027.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052647224&doi=10.1175%2fJAS-D-18-0027.1&partnerID=40&md5=67f1f617fa7a683dd8f449a00c8e679b","Direct numerical simulations resolving meter and submeter scales in the cloud-top region of stratocumulus are used to investigate the interactions between a mean vertical wind shear and in-cloud turbulence driven by evaporative and radiative cooling. There are three major results. First, a critical velocity jump (Δu)crit exists, above which shear significantly broadens the entrainment interfacial layer (EIL), enhances cloud-top cooling, and increases the mean entrainment velocity; shear effects are negligible when the velocity jump is below (Δu)crit. Second, a depletion velocity jump (Δu)dep exists, above which shear-enhanced mixing reduces cloud-top radiative cooling, thereby weakening the large convective motions; shear effects remain localized within the EIL when the velocity jump is below (Δu)dep. The critical velocity jump and depletion velocity jump are provided as a function of in-cloud and free-tropospheric conditions, and one finds (Δu)crit ≃ 1-4ms-1 and (Δu)dep ≃ 3-10ms-1 for typical subtropical conditions. Third, the individual contributions to the mean entrainment velocity from mixing, radiative cooling, and evaporative cooling strongly depend on the choice of the reference height where the entrainment velocity is calculated. This result implies that the individual contributions to the mean entrainment velocity should be estimated at a comparable height while deriving entrainment-rate parameterizations.Astrong shear alters substantially the magnitude and the height where these individual contributions reach their maxima, which further demonstrates the importance of shear on the dynamics of stratocumulus clouds. © 2018 American Meteorological Society."
"57189488148;7102875574;","Exploring the climatic response to wide variations in ocean heat transport on an aquaplanet",2018,"10.1175/JCLI-D-17-0856.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050250007&doi=10.1175%2fJCLI-D-17-0856.1&partnerID=40&md5=0a8d7f705d9cdb9740c01487014f74dd","The climatic impact of ocean heat transport (OHT) is studied in a series of idealized aquaplanet climate model experiments. OHT is prescribed through a simple geometrical formula spanning a wide variety of amplitudes and meridional extents. Calculations with a comprehensive GCM are compared against a simple diffusive energy balance model (EBM). The GCM response differs from the EBM in several important ways that illustrate linkages between atmospheric dynamics and radiative processes. Increased OHT produces global mean warming at a rate of 2 K PW-1 OHT across 30° and a strong reduction in meridional temperature gradient. The tropics remain nearly isothermal despite locally large imposed ocean heat uptake. The warmer climate features reduced equatorial convection, moister subtropics, reduced cloudiness, and partial but incomplete compensation in atmospheric heat transport. Many of these effects are linked to a weakened Hadley circulation. Both the warming pattern and hydrological changes differ strongly from those driven by CO2. Similar results are found at 0° and 23.45° obliquity. It is argued that clouds, rather than clear-sky radiative processes, are principally responsible for the global warming and tropical thermostat effects. Cloud changes produce warming in all cases, but the degree of warming depends strongly on the meridional extent of OHT. The strongest warming occurs in response to mid- to high-latitude OHT convergence, which produces widespread loss of boundary layer clouds. Temperature responses to increased OHT are quantitatively reproduced in the EBM by imposing GCM-derived cloud radiative effects as additional forcing. © 2018 American Meteorological Society."
"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."
"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."
"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."
"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."
"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"
"10243650000;10241250100;55686667100;55537426400;10241462700;7003420726;35580303100;57200122928;57200123725;57208483843;36701462300;6603370049;7102857642;","Effectiveness and limitations of parameter tuning in reducing biases of top-of-atmosphere radiation and clouds in MIROC version 5",2017,"10.5194/gmd-10-4647-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039761995&doi=10.5194%2fgmd-10-4647-2017&partnerID=40&md5=981c8a5fe054dc30a54be81b5a708329","This study discusses how much of the biases in top-of-atmosphere (TOA) radiation and clouds can be removed by parameter tuning in the present-day simulation of a climate model in the Coupled Model Inter-comparison Project phase 5 (CMIP5) generation. We used output of a perturbed parameter ensemble (PPE) experiment conducted with an atmosphere-ocean general circulation model (AOGCM) without flux adjustment. The Model for Interdisciplinary Research on Climate version 5 (MIROC5) was used for the PPE experiment. Output of the PPE was compared with satellite observation data to evaluate the model biases and the parametric uncertainty of the biases with respect to TOA radiation and clouds. The results indicate that removing or changing the sign of the biases by parameter tuning alone is difficult. In particular, the cooling bias of the shortwave cloud radiative effect at low latitudes could not be removed, neither in the zonal mean nor at each latitude-longitude grid point. The bias was related to the overestimation of both cloud amount and cloud optical thickness, which could not be removed by the parameter tuning either. However, they could be alleviated by tuning parameters such as the maximum cumulus updraft velocity at the cloud base. On the other hand, the bias of the shortwave cloud radiative effect in the Arctic was sensitive to parameter tuning. It could be removed by tuning such parameters as albedo of ice and snow both in the zonal mean and at each grid point. The obtained results illustrate the benefit of PPE experiments which provide useful information regarding effectiveness and limitations of parameter tuning. Implementing a shallow convection parameterization is suggested as a potential measure to alleviate the biases in radiation and clouds. © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License."
"57193321502;6603925960;57207507108;57193321831;7003865921;57203247832;","Using Space Lidar Observations to Decompose Longwave Cloud Radiative Effect Variations Over the Last Decade",2017,"10.1002/2017GL074628","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040067202&doi=10.1002%2f2017GL074628&partnerID=40&md5=fb933b7cdb1b39c595f9e35a2c88db60","Measurements of the longwave cloud radiative effect (LWCRE) at the top of the atmosphere assess the contribution of clouds to the Earth warming but do not quantify the cloud property variations that are responsible for the LWCRE variations. The CALIPSO space lidar observes directly the detailed profile of cloud, cloud opacity, and cloud cover. Here we use these observations to quantify the influence of cloud properties on the variations of the LWCRE observed between 2008 and 2015 in the tropics and at global scale. At global scale, the method proposed here gives good results except over the Southern Ocean. We find that the global LWCRE variations observed over ocean are mostly due to variations in the opaque cloud properties (82%); transparent cloud columns contributed 18%. Variation of opaque cloud cover is the first contributor to the LWCRE evolution (58%); opaque cloud temperature is the second contributor (28%). ©2017. American Geophysical Union. All Rights Reserved."
"57193321502;6603925960;57207507108;57193321831;6701705691;7003865921;56493740900;","The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated",2017,"10.5194/amt-10-4659-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037619961&doi=10.5194%2famt-10-4659-2017&partnerID=40&md5=49c11595dc830ea4a2e2e74b451031fb","According to climate model simulations, the changing altitude of middle and high clouds is the dominant contributor to the positive global mean longwave cloud feedback. Nevertheless, the mechanisms of this longwave cloud altitude feedback and its magnitude have not yet been verified by observations. Accurate, stable, and long-term observations of a metric-characterizing cloud vertical distribution that are related to the longwave cloud radiative effect are needed to achieve a better understanding of the mechanism of longwave cloud altitude feedback. This study shows that the direct measurement of the altitude of atmospheric lidar opacity is a good candidate for the necessary observational metric. The opacity altitude is the level at which a spaceborne lidar beam is fully attenuated when probing an opaque cloud. By combining this altitude with the direct lidar measurement of the cloud-top altitude, we derive the effective radiative temperature of opaque clouds which linearly drives (as we will show) the outgoing longwave radiation. We find that, for an opaque cloud, a cloud temperature change of 1 K modifies its cloud radiative effect by 2 W m-2. Similarly, the longwave cloud radiative effect of optically thin clouds can be derived from their top and base altitudes and an estimate of their emissivity. We show with radiative transfer simulations that these relationships hold true at single atmospheric column scale, on the scale of the Clouds and the Earth's Radiant Energy System (CERES) instantaneous footprint, and at monthly mean 2° × 2° scale. Opaque clouds cover 35 % of the ice-free ocean and contribute to 73 % of the global mean cloud radiative effect. Thin-cloud coverage is 36 % and contributes 27 % of the global mean cloud radiative effect. The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated provides a simple formulation of the cloud radiative effect in the longwave domain and so helps us to understand the longwave cloud altitude feedback mechanism."
"56382795700;7003495004;6701618694;36124109400;","Cloud radiative effect, cloud fraction and cloud type at two stations in Switzerland using hemispherical sky cameras",2017,"10.5194/amt-10-4587-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036610535&doi=10.5194%2famt-10-4587-2017&partnerID=40&md5=ccd23e3180ee802e0d75d364bac7eb11","The current study analyses the cloud radiative effect during the daytime depending on cloud fraction and cloud type at two stations in Switzerland over a time period of 3 to 5 years. Information on fractional cloud coverage and cloud type is retrieved from images taken by visible all-sky cameras. Cloud-base height (CBH) data are retrieved from a ceilometer and integrated water vapour (IWV) data from GPS measurements. The longwave cloud radiative effect (LCE) for low-level clouds and a cloud coverage of 8 oktas has a median value between 59 and 72ĝ€Wmĝ'2. For mid- and high-level clouds the LCE is significantly lower. It is shown that the fractional cloud coverage, the CBH and IWV all have an influence on the magnitude of the LCE. These observed dependences have also been modelled with the radiative transfer model MODTRAN5. The relative values of the shortwave cloud radiative effect (SCErel) for low-level clouds and a cloud coverage of 8 oktas are between ĝ'90 and ĝ'62ĝ€%. Also here the higher the cloud is, the less negative the SCErel values are. In cases in which the measured direct radiation value is below the threshold of 120ĝ€Wmĝ'2 (occulted sun) the SCErel decreases substantially, while cases in which the measured direct radiation value is larger than 120ĝ€Wmĝ'2 (visible sun) lead to a SCErel of around 0ĝ€%. In 14 and 10ĝ€% of the cases in Davos and Payerne respectively a cloud enhancement has been observed with a maximum in the cloud class cirrocumulus-altocumulus at both stations. The calculated median total cloud radiative effect (TCE) values are negative for almost all cloud classes and cloud coverages. © Author(s) 2017."
"57188714718;7005135473;","The impact of seasonalities on direct radiative effects and radiative heating rates of absorbing aerosols above clouds",2017,"10.1002/qj.3012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016612900&doi=10.1002%2fqj.3012&partnerID=40&md5=76fe046a87390a106fe9aa7703b77141","The impact of seasonalities on direct radiative effects (DREs) and radiative heating rates (RHRs) of absorbing aerosols above clouds in the southeast Atlantic is examined using radiative transfer calculations. For an aerosol optical thickness of 0.6 located between 0 and 4 km, a cloud optical thickness of 9.0 and a cloud effective radius of 12.8 µm at 0.55 µm located between 1 and 2 km, the diurnally averaged RHR at noon in the aerosol layer increases from ∼6.6 K day−1 in June to ∼8.9 K day−1 in October. In June (October), the RHR in the cloud layer at noon is 1.3 (1.7) K day−1 higher than the case of pristine clouds. However, an elevated aerosol layer (2–4 km) reduces the RHR by ∼0.2 K day−1 in the cloud layer relative to a pristine cloudy case. The DRE at top-of-atmosphere (TOA) reaches its peak when the solar zenith angle (SZA) is 54°. The DRE increases (decreases) with SZA for SZA less (greater) than 54°. The primary peak DRE is ∼29.5 W m−2 at 5.0°S 5.0°E, occurring at 0800 UTC. At noon, the DRE at TOA is ∼18.9, ∼20.5 and ∼23.1 W m−2 at 5.0°S, 15.0°S and 25.0°S along 5.0°E, respectively. This study provides data and theoretical understanding to help positioning science flights that target measurements of above-cloud aerosol radiative effects. © 2017 Royal Meteorological Society"
"12040335900;25723417400;7402085600;7006614696;57194553129;55890394800;55814053500;","Revisiting the iris effect of tropical cirrus clouds with trmm and a-train satellite data",2017,"10.1002/2016JD025827","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020785188&doi=10.1002%2f2016JD025827&partnerID=40&md5=5112221dc3ce3ea33d483449bd8a58b3","Just as the iris of human eye controls the light influx (iris effect), tropical anvil cirrus clouds may regulate the Earth’s surface warming by controlling outgoing longwave radiation. This study examines this possible effect with monthly satellite observations such as Tropical Rainfall Measuring Mission (TRMM) precipitation, Moderate Resolution Imaging Spectroradiometer cirrus fraction, and Clouds and the Earth’s Radiant Energy System top-of-the-atmosphere radiative fluxes averaged over different tropical domains from March 2000 to October 2014. To confirm that high-level cirrus is relevant to this study, Cloud-Aerosol Lidar with Orthogonal Polarization high cloud observations were also analyzed from June 2006 to December 2015. Our analysis revealed that the increase in sea surface temperature in the tropical western Pacific tends to concentrate convective cloud systems. This concentration effect very likely induces the significant reduction of both stratiform rain rate and cirrus fraction, without appreciable change in the convective rain rate. This reduction of stratiform rain rate and cirrus fraction cannot be found over its subregion or the tropical eastern Pacific, where the concentration effect of anvil cirrus is weak. Consistently, over the tropical western Pacific, the higher ratio of convective rain rate to total rain rate (i.e., precipitation efficiency) significantly correlates with warmer sea surface temperature and lower cirrus fraction. The reduced cirrus eventually increased outgoing longwave radiation to a greater degree than absorbed solar radiation. Finally, the negative relationship between precipitation efficiency and cirrus fraction tends to correspond to a low global equilibrium climate sensitivity in the models in the Coupled Model Intercomparison Project Phase 5. This suggests that tropical anvil cirrus clouds exert a negative climate feedback in strong association with precipitation efficiency. © 2017. American Geophysical Union. All Rights Reserved."
"25941200000;8397494800;7410070663;6603613067;","A parametrization of 3-D subgrid-scale clouds for conventional GCMs: Assessment using A-Train satellite data and solar radiative transfer characteristics",2016,"10.1002/2015MS000601","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979725527&doi=10.1002%2f2015MS000601&partnerID=40&md5=5b6f0967395c4945565c0783b955c5be","A stochastic algorithm for generating 3-D cloud fields based on profiles of cloud fraction (Formula presented.) and mean cloud water content is presented and assessed using cloud properties inferred from A-Train satellite data. The ultimate intention is to employ the algorithm, along with 3-D radiative transfer (RT) models, in Global Climate Models (GCMs). The algorithm approaches cloud fields as whole objects demarcated by contiguous layers with (Formula presented.). This contrasts with conventional GCM radiation routines that deal with clouds on a per-(arbitrary) layer basis. A-Train cloud data for August 2007 were partitioned into ∼29,000 domains, each ∼280 km long, to represent nominal GCM columns. For each A-Train/stochastic pair of domains, profiles of domain-averaged fluxes were computed by a 1-D broadband solar RT model in Independent Column Approximation mode. Globally averaged, mean bias error for upwelling radiation at top-of-atmosphere (TOA) is 6.8 W m−2. Upon advancing the RT model to 2-D, differences between 1-D and 2-D upwelling fluxes at TOA for A-Train domains differed from corresponding differences for model-generated domains by ∼1 W m−2, on average, with differences for the model domains exhibiting stronger dependence on solar zenith angle (Formula presented.). Moving on to 3-D RT for model domains, 1-D–3-D differences became slightly stronger functions of (Formula presented.) thanks mostly to accentuated 3-D effects at small (Formula presented.). Simple parametrizations for the stochastic algorithm's variables that govern horizontal and vertical structure of clouds should be adequate to capture the ramifications of systematic neglect of 3-D solar RT in GCMs. © 2016. The Authors and Her Majesty the Queen in Right of Canada. Reproduced with the permission of the Minister of the Environment."
"12761291000;57112070700;","Stratocumulus radiative effect, multiple equilibria of the well-mixed boundary layer and transition to shallow convection",2016,"10.1002/qj.2762","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962775148&doi=10.1002%2fqj.2762&partnerID=40&md5=ff9422485c3cb36d44a67f6a9f3d9fea","The present work investigates the equilibrium of the atmospheric boundary layer (ABL) over the ocean using a large-eddy simulation model, with different lower-boundary sea-surface temperatures (SSTs) and different initial conditions. For low SSTs, one of two equilibria is reached depending on the initial conditions. One equilibrium is characterized by a deep, stratocumulus-capped ABL, while the other is a thin, cloud-free ABL. Cloud radiative cooling at the top of the stratocumulus is crucial to the existence of the stratocumulus equilibrium. If the SST is increased, the stratocumulus equilibrium becomes deeper and the cloud radiative effect reaches a maximum before decreasing due to buoyancy reversal and decoupling. This decrease of cloud radiative effect with SST eventually suppresses the stratocumulus equilibrium at higher SSTs-all initial conditions then lead to the cloud-free equilibrium. If the SST is increased further, the cloud-free equilibrium becomes a deeper, shallow convective equilibrium with cumuli in the upper part of the ABL. This shallow convective ABL is deepened by the cloud radiative effect. Our results suggest that the transition from stratocumulus decks in the eastern subtropical oceans to the trade-wind shallow convective regions is essentially a transition from one basin of attraction, which disappears, to another. © 2016 Royal Meteorological Society."
"56640482500;7404765381;","Cloud impacts on pavement temperature and shortwave radiation",2016,"10.1175/JAMC-D-16-0094.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998591776&doi=10.1175%2fJAMC-D-16-0094.1&partnerID=40&md5=2da08c0ce586835a54679880ccb47e79","Forecast systems provide decision support for end users ranging from the solar energy industry to municipalities concerned with road safety. Pavement temperature is an important variable when considering vehicle response to various weather conditions. A complex relationship exists between tire and pavement temperatures that affects vehicle performance. Many forecast systems suffer from inaccurate radiation forecasts resulting in part from the inability to model different types of clouds and their influence on radiation. This research focuses on forecast improvement by determining how cloud type impacts pavement temperature and the amount of shortwave radiation reaching the surface. The study region is the Great Plains where surface radiation data were obtained from the High Plains Regional Climate Center's Automated Weather Data Network stations. Pavement temperature data were obtained from the Meteorological Assimilation Data Ingest System. Cloud-type identification was possible via the Naval Research Laboratory Cloud Classification algorithm, and clouds were subsequently sorted into five distinct groups: clear conditions, low clouds, middle clouds, high clouds, and cumuliform clouds. Statistical analyses during the daytime in June 2011 revealed that cloud cover lowered pavement temperatures by up to approximately 10°C and dampened downwelling shortwave radiation by up to 400 W m-2. These pavement temperatures and surface radiation observations were strongly correlated, with a maximum correlation coefficient of 0.83. A comparison between cloud-type group identified and cloud cover observed from satellite images provided a measure of confidence in the results and identified cautions with using satellite-based cloud detection. © 2016 American Meteorological Society."
"37027011900;6603925960;7102410621;57207507108;30667558200;35203328900;6507495053;8669401600;","An EarthCARE/ATLID simulator to evaluate cloud description in climate models",2015,"10.1002/2015JD023919","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956775517&doi=10.1002%2f2015JD023919&partnerID=40&md5=d3b11c64643a9d276ee42fe3b14c8b71","Clouds still remain the largest source of uncertainty in model-based predictions of future climate; thus, the description of the clouds in climate models needs to be evaluated. In particular, the cloud detailed vertical distribution that impacts directly the cloud radiative effect needs to be evaluated. Active satellite sensors directly measure the cloud vertical distribution with high accuracy; their observations should be used for model evaluation together with a satellite simulator in order to allow fair comparison between models and observations. The next cloud lidar in space, EarthCARE/ATmospheric LIDar (ATLID), is planned for launch in 2018, while the current spaceborne cloud lidar CALIPSO/CALIOP is expected to stop collecting data within the next coming years. Here we describe the characteristics of the ATLID on board the EarthCARE satellite (spatial resolution, signal-to-noise ratio, wavelength, field of view, pulse repetition frequency, orbit, and high-spectral resolution lidar) that need to be taken into account to build a Cloud Feedback Model Intercomparison Project Observation Simulator Package (COSP)/ATLID simulator. We then present the COSP/ATLID simulator, and the low-, middle-, high-level cloud covers it produces, as well as the zonal mean cloud fraction profiles and the height-intensity histograms that are simulated by COSP/ATLID when overflying an atmosphere predicted by LMDZ5 global circulation model. Finally, we compare the clouds simulated by COSP/ATLID with those simulated by COSP/CALIPSO when overflying the same atmosphere. As the main differences between ATLID and CALIOP are taken into account in the simulators, the differences between COSP/ATLID and COSP/CALIPSO cloud covers are less than 1% in nighttime conditions Key Point EarthCARE simulator to evaluate cloud in climate models. © 2015. American Geophysical Union. All Rights Reserved."
"7004893330;15726251700;55703589700;55547129338;","A satellite view of the radiative impact of clouds on surface downward fluxes in the Tibetan Plateau",2015,"10.1175/JAMC-D-14-0183.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943780267&doi=10.1175%2fJAMC-D-14-0183.1&partnerID=40&md5=7be4f7509e5bed095f4d3b55d07bc5cf","Using 13 yr of satellite observations for the Tibetan Plateau, the sensitivities (or partial derivatives) of daytime surface downward shortwave and longwave fluxes with respect to changes in cloud cover and cloud optical thickness are investigated and quantified. Coincident cloud and surface flux retrievals from the NASA Moderate Resolution Imaging Spectroradiometer and the Clouds and the Earth's Radiant Energy System, respectively, as well as ground-based observations at 11 stations across the plateau are used to examine the spatial and seasonal variability of this sensitivity over the entire plateau. The downward shortwave flux is found to be modulated primarily by changes in cloud cover, but changes in optical thickness also have an impact, as revealed by a multiple regression fit. The coefficient of determination of the regression increases by more than 15% when optical thickness is added. There is significant seasonal and regional variability in the cloud radiative impact. On average, at all stations, the sensitivity of surface shortwave flux to changes in cloud cover is about -0.5 ± 0.1 W m-2 %-1 in winter according to both ground-based and satellite observations but in summer reaches -1.5 ± 0.3 and -1.8 ± 0.2 W m-2 %-1 according to ground-based and satellite observations, respectively. Cloud cover itself has little impact on the sensitivity when clouds are optically thin, but above an optical thickness of 12, sensitivities increase with both cloud cover and cloud optical thickness. The daytime longwave flux response to changes in cloud properties is also examined. The radiative impact of a decrease in cloud cover on the surface net flux can be offset or even canceled if cloud opacity increases by 5%-10%. © 2015 American Meteorological Society."
"9635764200;","Cloud responses in the AMIP simulations of CMIP5 models in the southeastern Pacific marine subsidence region",2015,"10.1002/joc.4181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84938854585&doi=10.1002%2fjoc.4181&partnerID=40&md5=79fed06511b2d3f81cf183a02e4d2bc6","The sensitivity of regimes dominated by low clouds has been identified as the largest contributor to uncertainties in tropical cloud feedback estimates in climate models. The Atmospheric Model Intercomparison Project simulations of the low cloud response to sea surface temperature (SST) are compared with satellite observations in the southeastern Pacific subsidence region. The model ensemble annual average cloud fraction is only about 10% lower than Moderate Resolution Imaging Spectroradiometer observations; however, many models compensate by overestimating the cloud liquid water path (LWP), especially in areas typically associated with shallow cumulus. Analysis of the monthly distribution also shows that models have considerable difficulty in simulating the annual cycle in the cloud radiative effect (CRE), cloud fraction, and LWP likely due in part to underestimation of the strength of lower tropospheric stability and the depth of the boundary layer. The interannual sensitivity of CRE to SST agrees with observations in about half of the models, with the other half generally underestimating the cloud radiative forcing sensitivity. Model-observational differences are driven by the varying interannual responses in cloud fraction and LWP. Most models, including those that capture the mean interannual sensitivity of CRE to SST, have lower sensitivity in cloud fraction that is compensated by oversensitivity in the cloud LWP, especially in areas of more frequent shallow cumulus. Results presented here also highlight the possibility of using the vertical gradient of moist static energy (MSE) to test the fidelity of a model's representation of clouds and cloud sensitivity. Models that reproduce the observed distribution of cloud fraction with the lower tropospheric MSE gradient not only show better regional distribution and annual cycle in clouds and radiative forcing, but also demonstrate cloud and radiative sensitivities to SST that are more well correlated with the observed cloud sensitivities. © 2015 Royal Meteorological Society."
"17135286400;56611366900;","Statistical characteristics of cloud variability. Part 2: Implication for parameterizations of microphysical and radiative transfer processes in climate models",2014,"10.1002/2014JD022003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018214830&doi=10.1002%2f2014JD022003&partnerID=40&md5=094df3af74cda81b26743af46b0a333a","The effects of subgrid cloud variability on grid-average microphysical rates and radiative fluxes are examined by use of long-term retrieval products at the Tropical West Pacific, Southern Great Plains, and North Slope of Alaska sites of the Department of Energy’s Atmospheric Radiation Measurement program. Four commonly used distribution functions, the truncated Gaussian, Gamma, lognormal, and Weibull distributions, are constrained to have the same mean and standard deviation as observed cloud liquid water content. The probability density functions are then used to upscale relevant physical processes to obtain grid-average process rates. It is found that the truncated Gaussian representation results in up to 30% mean bias in autoconversion rate, whereas the mean bias for the lognormal representation is about 10%. The Gamma and Weibull distribution function performs the best for the grid-average autoconversion rate with the mean relative bias less than 5%. For radiative fluxes, the lognormal and truncated Gaussian representations perform better than the Gamma and Weibull representations. The results show that the optimal choice of subgrid cloud distribution function depends on the nonlinearity of the process of interest, and thus, there is no single distribution function that works best for all parameterizations. Examination of the scale (window size) dependence of the mean bias indicates that the bias in grid-average process rates monotonically increases with increasing window sizes, suggesting the increasing importance of subgrid variability with increasing grid sizes. © 2014. American Geophysical Union. All rights reserved."
"15751598400;7402480218;","Spatial variability of surface irradiance measurements at the Manus ARM site",2014,"10.1002/2013JD021187","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84901708454&doi=10.1002%2f2013JD021187&partnerID=40&md5=7b8e2f6484ca131f018ea9e284bfb751","The location of the Atmospheric Radiation Measurement (ARM) site on Manus island was chosen because it is very close to the coast, in a flat, near-sea level area of the island, hopefully minimizing the impact of local island effects on the meteorology of the measurements. In this study, we confirm that the Manus site is indeed less impacted by the island meteorology than slightly inland by comparing over a year of broadband surface irradiance and ceilometer measurements and derived quantities at the standard Manus site and a second location 7 km away as part of the ARM Madden Julian Oscillation Investigation Experiment (AMIE)-Manus campaign. The two sites show statistically similar distributions of irradiance and other derived quantities for all wind directions except easterly winds, when the inland site is downwind from the standard Manus site. Under easterly wind conditions, which occur 17% of the time, there is a higher occurrence of cloudiness at the downwind site likely due to land heating and orographic effects. This increased cloudiness is caused by scattered clouds often with bases around 700 m in altitude. While the central Manus site consistently measures a frequency of occurrence of low clouds (cloud base height less than 1200 m) about 25% of the time regardless of wind direction, the AMIE site has higher frequencies of low clouds (38%) when winds are from the east. This increase in low, locally produced clouds causes an additional -20 W/m2 shortwave surface cloud radiative effect at the AMIE site than the Manus site. © 2014. American Geophysical Union. All Rights Reserved."
"55716181900;6602403713;7003668116;","Evaluating the accuracy of a high-resolution model simulation through comparison with MODIS observations",2014,"10.1175/JAMC-D-13-0140.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897990862&doi=10.1175%2fJAMC-D-13-0140.1&partnerID=40&md5=c3c6598d6ad7a9f22a5768417ad5072f","Synthetic infrared brightness temperatures (BTs) derived from a high-resolution Weather Research and Forecasting (WRF) model simulation over the contiguous United States are compared with Moderate Resolution Imaging Spectroradiometer (MODIS) observations to assess the accuracy of the model-simulated cloud field.Asophisticated forward radiative transfer model (RTM) is used to compute the synthetic MODIS observations. A detailed comparison of synthetic and real MODIS 11-μm BTs revealed that the model simulation realistically depicts the spatial characteristics of the observed cloud features. Brightness temperature differences (BTDs) computed for 8.5-11 and 11-12μm indicate that the combined numerical model-RTM system realistically treats the radiative properties associated with optically thin cirrus clouds. For instance, much larger 11-12-μm BTDs occurred within thin clouds surrounding optically thicker, mesoscale cloud features. Although the simulated and observed BTD probability distributions for optically thin cirrus clouds had a similar range of positive values, the synthetic 11-μmBTs were much colder than observed. Previous studies have shown that MODIS cloud optical thickness values tend to be too large for thin cirrus clouds, which contributed to the apparent cold BT bias in the simulated thin cirrus clouds. Errors are substantially reduced after accounting for the observed optical thickness bias, which indicates that the thin cirrus clouds are realistically depicted during the model simulation. © 2014 American Meteorological Society."
"37051480000;6701511324;35392584500;","Monte Carlo-based subgrid parameterization of vertical velocity and stratiform cloud microphysics in ECHAM5.5-HAM2",2013,"10.5194/acp-13-7551-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921327302&doi=10.5194%2facp-13-7551-2013&partnerID=40&md5=000dcbf8064a10f5d6d8328367430d58","A new method for parameterizing the subgrid variations of vertical velocity and cloud droplet number concentration (CDNC) is presented for general circulation models (GCMs). These parameterizations build on top of existing parameterizations that create stochastic subgrid cloud columns inside the GCM grid cells, which can be employed by the Monte Carlo independent column approximation approach for radiative transfer. The new model version adds a description for vertical velocity in individual subgrid columns, which can be used to compute cloud activation and the subgrid distribution of the number of cloud droplets explicitly. Autoconversion is also treated explicitly in the subcolumn space. This provides a consistent way of simulating the cloud radiative effects with two-moment cloud microphysical properties defined at subgrid scale. The primary impact of the new parameterizations is to decrease the CDNC over polluted continents, while over the oceans the impact is smaller. Moreover, the lower CDNC induces a stronger autoconversion of cloud water to rain. The strongest reduction in CDNC and cloud water content over the continental areas promotes weaker shortwave cloud radiative effects (SW CREs) even after retuning the model. However, compared to the reference simulation, a slightly stronger SW CRE is seen e.g. over mid-latitude oceans, where CDNC remains similar to the reference simulation, and the in-cloud liquid water content is slightly increased after retuning the model. ©Author(s) 2013."
"12769875100;","The Role of Clouds: An Introduction and Rapporteur Report",2012,"10.1007/s10712-012-9182-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84862668973&doi=10.1007%2fs10712-012-9182-2&partnerID=40&md5=124ff0d440120d2c7c758b9e3beed101","This paper presents an overview of discussions during the Cloud's Role session at the Observing and Modelling Earth's Energy FlowsWorkshop. N. Loeb and B. Soden convened this session including 10 presentations by B. Stevens, B. Wielicki, G. Stephens, A. Clement, K. Sassen, D. Hartmann, T. Andrews, A. Del Genio, H. Barker, and M. Sugi addressing critical aspects of the role of clouds in modulating Earth energy flows. Presentation topics covered a diverse range of areas from cloud microphysics and dynamics, cloud radiative transfer, and the role of clouds in large-scale atmospheric circulations patterns in both observations and atmospheric models. The presentations and discussions, summarized below, are organized around several key questions raised during the session. (1) What is the best way to evaluate clouds in climate models? (2) How well do models need to represent clouds to be acceptable for making climate predictions? (3) What are the largest uncertainties in clouds? (4) How can these uncertainties be reduced? (5) What new observations are needed to address these problems? Answers to these critical questions are the topics of ongoing research and will guide the future direction of this area of research. © 2012 The Author(s)."
"30767858100;35330367300;7404243086;","Investigation of the vertical structure of warm-cloud microphysical properties using the cloud evolution diagram, CFODD, simulated by a three-dimensional spectral bin microphysical model",2012,"10.1175/JAS-D-11-0244.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84864830971&doi=10.1175%2fJAS-D-11-0244.1&partnerID=40&md5=f7639d4961e9b31fc4b9672f3a6905c2","This paper investigates the vertical structure of warm-cloud microphysical properties using a threedimensional (3D) spectral bin microphysical model. A time series of contoured frequency by optical depth diagrams(CFODDs), which were proposed by previous studies, are calculated for the first time by a 3Dmodel assuming two types of aerosol conditions (i.e., polluted and pristine). This contrasts with previous studies that obtained CFODDs using either a two-dimensional model or an accumulation of monthly and global observation data. The results show that the simulated CFODDs are characterized by distinctive patterns of radar reflectivities, similar to the patterns often observed by satellite remote sensing, even though the calculation domain of this study is limited to an area of 30×30 km 2, whereas the satellite observations are of a global scale. A cloud microphysical box model is then applied to the simulated cloud field at each time step to identify the dominant process for each of the patterns. The results reveal that the wide variety of satelliteobserved CFODD patterns can be attributed to different microphysical processes occurring in multiple cloud cells at various stages of the cloud life cycle. © 2012 American Meteorological Society."
"57200530823;25227357000;7102018821;7401895830;23028717700;","Direct and semi-direct radiative effects of anthropogenic aerosols in the Western United States: Seasonal and geographical variations according to regional climate characteristics",2012,"10.1007/s10584-011-0169-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857924587&doi=10.1007%2fs10584-011-0169-7&partnerID=40&md5=7bca4ac1fe2b261fdd178f8eaf8b16f9","The direct and semi-direct radiative effects of anthropogenic aerosols on the radiative transfer and cloud fields in the Western United States (WUS) according to seasonal aerosol optical depth (AOD) and regional climate are examined using a regional climate model (RCM) in conjunction with the aerosol fields from a GEOS-Chem chemical-transport model (CTM) simulation. The two radiative effects cannot be separated within the experimental design in this study, thus the combined direct- and semi-direct effects are called radiative effects hereafter. The CTM shows that the AOD associated with the anthropogenic aerosols is chiefly due to sulfates with minor contributions from black carbon (BC) and that the AOD of the anthropogenic aerosol varies according to local emissions and the seasonal low-level winds. The RCM-simulated anthropogenic aerosol radiative effects vary according to the characteristics of regional climate, in addition to the AOD. The effects on the top of the atmosphere (TOA) outgoing shortwave radiation (OSRT) range from -0.2 Wm -2 to -1 Wm -2. In Northwestern US (NWUS), the maximum and minimum impact of anthropogenic aerosols on OSRT occurs in summer and winter, respectively, following the seasonal AOD. In Arizona-New Mexico (AZNM), the effect of anthropogenic sulfates on OSRT shows a bimodal distribution with winter/summer minima and spring/fall maxima, while the effect of anthropogenic BC shows a single peak in summer. The anthropogenic aerosols affect surface insolation range from -0.6 Wm -2 to -2.4 Wm -2, with similar variations found for the effects on OSRT except that the radiative effects of anthropogenic BC over AZNM show a bimodal distribution with spring/fall maxima and summer/winter minima. The radiative effects of anthropogenic sulfates on TOA outgoing longwave radiation (OLR) and the surface downward longwave radiation (DLRS) are notable only in summer and are characterized by strong geographical contrasts; the summer OLR in NWUS (AZNM) is reduced (enhanced) by 0.52 Wm -2 (1.14 Wm -2). The anthropogenic sulfates enhance (reduce) summer DLRS by 0.2 Wm -2 (0.65 Wm -2) in NWUS (AZNM). The anthropogenic BC affect DLRS noticeably only in AZNM during summer. The anthropogenic aerosols affect the cloud water path (CWP) and the radiative transfer noticeably only in summer when convective clouds are dominant. Primarily shortwave-reflecting anthropogenic sulfates decrease and increase CWP in AZNM and NWUS, respectively, however, the shortwave-absorbing anthropogenic BC reduces CWP in both regions. Due to strong feedback via convective clouds, the radiative effects of anthropogenic aerosols on the summer radiation field are more closely correlated with the changes in CWP than the AOD. The radiative effect of the total anthropogenic aerosols is dominated by the anthropogenic sulfates that contribute more than 80% of the total AOD associated with the anthropogenic aerosols. © 2011 Springer Science+Business Media B.V."
"7402480218;7005877775;","Quantification of the impact of nauru island on ARM measurements",2012,"10.1175/JAMC-D-11-0174.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861710773&doi=10.1175%2fJAMC-D-11-0174.1&partnerID=40&md5=19e2096d652a4d427895cfe458fe921e","Nauru Island at times generates low clouds that impact low-level cloud statistics and downwelling shortwave radiation measurements made at the Atmospheric Radiation Measurement Program (ARM) site. This study uses five years of Nauru data to quantify the island impact on the site measurements. The results indicate that the solar-heating-produced Nauru island effect occurs about 11% of the time during daylight hours. The island effect increases the 500-1000-m cloud base occurrence by 15%-20% when clouds occur, but because the island effect only occurs 11% of the time the overall increase in daylight low-cloud statistics is 2%, or 1% for 24-h statistics. In a similar way, the island effect produces a reduction of about 17% in the downwelling shortwave (SW) radiation across the daylight hours during the 11% of the time it occurs, an overall 2% daylight (or 1% for 24 h) average reduction. The island effect produces frequent positive downwelling SW cloud effects, in particular during the morning, which tend to somewhat mitigate the overall decrease in downwelling SW radiation that is due to clouds. This produces 17 W m -2 less daylight average SW cloud effect relative to non-island-effect times, in particular for the convectively suppressed regime that typifies island-effect-producing conditions. For long-term overall statistical studies such as model and satellite comparisons, the2%daylight (or1%per 24 h) average increase in low-level cloud occurrence and decrease in downwelling SW are not of large concern as long as researchers are aware of them. For shorter-term studies, however, or those that separate data by conditions such as convectively active/suppressed regimes, the Nauru island effect can have significant impacts. © 2012 American Meteorological Society."
"7405361965;","Effects of vertical wind shear, radiation, and ice clouds on a torrential rainfall event in China",2011,"10.1029/2010JD014518","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79952770357&doi=10.1029%2f2010JD014518&partnerID=40&md5=73a32ab997f5b9c1338cfcd009ee24b8","The effects of vertical wind shear, radiation, and ice clouds on surface rainfall processes associated with the torrential rainfall event over Jinan, China, during July 2007 are investigated through a series of sensitivity experiments. All experiments are integrated with an imposed large-scale vertical velocity and zonal wind from the National Centers for Environmental Prediction Global Data Assimilation System for 36 h, while vertical wind shear, cloud radiative effects, cloud-radiation interaction, and ice microphysics are, respectively, suppressed in the sensitivity experiments. The exclusion of ice clouds decreases model domain mean surface rain rate by 12.9%, whereas the mean rain rates are less sensitive to vertical wind shear, cloud radiative effects, and cloud-radiation interaction. The reduction in the mean rain rate resulting from the removal of ice clouds is primarily associated with the decrease in net condensation. The budget analysis of the mean perturbation kinetic energy shows that the barotropic conversion process associated with vertical wind shear does not increase perturbation kinetic energy and thus does not increase the mean rain rate. The increase in radiative cooling resulting from the exclusion of cloud radiative effects is largely offset by the decrease in heat divergence, which results in the insensitivity of the mean rain rate to cloud radiative effects. Copyright 2011 by the American Geophysical Union."
"6508287655;7102797196;7005931768;35330367300;21740108200;","Influence of inhomogeneous cloud fields on optical properties retrieved from satellite observations",2007,"10.1029/2006JD007891","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548652326&doi=10.1029%2f2006JD007891&partnerID=40&md5=b9492ecc338acafab98be79c65c54cff","Analyses of solar radiation exchanges between the atmosphere and clouds are vital for the understanding of climate processes and cycles. Comparisons of satellite-to-satellite or satellite-to-ground-truth observations aiming at, elucidating the radiative behavior of atmospheric components (clouds, aerosols, gas, etc.), or validating data of a particular satellite are a common practice in global radiation investigations. In order to assess the quality of cloud optical properties derived from Geostationary Meteorological Satellite-5/ Stretched Visible Infrared Spin Scan Radiometer (GMS-5/SVISSR), the former procedure (satellite-to-satellite comparison) was used. Data derived from GMS-5/SVISSR satellite were compared with those from the polar-orbiting Terra-Moderate Resolution Imaging Spectroradiometer (Terra-MODIS) satellite. This comparison showed serious discrepancies between cloud optical depth (COD) data retrieved from the two satellites' observations. GMS-5/SVISSR-retrieved COD appeared mostly lower than that of Terra-MODIS. To understand the origin of such differences, an identification procedure of the major factors likely to affect these data is conducted. Some of these factors were the satellite viewing and solar conditions, the cloud thermodynamic phase differentiation and particle effective radius, and the cloud inhomogeneity. Then emphasis was put on the examination of the latter effect (i.e., the cloud inhomogeneity). The analysis procedure was as follows: First, data having close-viewing geometries between both satellites were selected and used to understand the effects of the remaining factors. Among these, the cloud thermodynamic phase appeared to play the major role as analyses showed that most of the COD differences between both satellites were confined within ice clouds while warm clouds had the least discrepancies. This would suggest that the choice of a water cloud particle radiative transfer model to analyze a 2-phase cloud radiation data, as used here, may produce large uncertainties in ice COD retrievals from at least one of the satellites. To avoid the cloud phase problem, a more restrictive data set comprising only water clouds (besides close-viewing geometries between both satellites) was selected, and the impact of the degree of cloud inhomogeneity on the COD retrievals was evaluated. The study reveals that the 3-D radiative effects deriving from the external cloud inhomogeneity, i.e., cloud asymmetry and structured sides, were the most influencing properties here. The GMS-5/SVISSR interpretation of inhomogeneous cloud optical properties showed larger uncertainties than that of Terra-MODIS. Furthermore, COD values of GMS-5/SVISSR were systematically lower than those of Terra-MODIS for the pixels at shadow sides of the cloud, while at illuminated sides they often showed higher values. For gentle or near-plane-parallel cloud surfaces, fewer discrepancies were noticed (the best agreement between both satellites' retrievals). At steep slopes of the shadow and illuminated cloud sides, GMS-5/SVISSR average COD data were respectively under- and overestimated compared to those of Terra-MODIS. COD differences between the two satellites could be sometimes higher than 30% for slopes steeper than 0.5 K/km. Copyright 2007 by the American Geophysical Union."
"57213020763;7003478309;7006128738;6701884630;","Clear-sky aerosol radiative forcing effects based on multi-site AERONET observations over Europe",2007,"10.1007/s00703-006-0212-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34447095845&doi=10.1007%2fs00703-006-0212-9&partnerID=40&md5=0ca75dfa83d8b5b9fee256716ebdedc4","One of the great unknowns in climate research is the contribution of aerosols to climate forcing and climate perturbation. In this study, retrievals from AERONET are used to estimate the direct clear-sky aerosol top-of-atmosphere and surface radiative forcing effects for 12 multi-site observing stations in Europe. The radiative transfer code sdisort in the libRadtran environment is applied to accomplish these estimations. Most of the calculations in this study rely on observations which have been made for the years 1999, 2000, and 2001. Some stations do have observations dating back to the year of 1995. The calculations rely on a pre-compiled aerosol optical properties database for Europe. Aerosol radiative forcing effects are calculated with monthly mean aerosol optical properties retrievals and calculations are presented for three different surface albedo scenarios. Two of the surface albedo scenarios are generic by nature bare soil and green vegetation and the third relies on the ISCCP (International Satellite Cloud Climatology Project) data product. The ISCCP database has also been used to obtain clear-sky weighting fractions over AERONET stations. The AERONET stations cover the area 0° to 30° E and 42° to 52° N. AERONET retrievals are column integrated and this study does not make any seperation between the contribution of natural and anthropogenic components. For the 12 AERONET stations, median clear-sky top-of-atmosphere aerosol radiative forcing effect values for different surface albedo scenarios are calculated to be in the range of - 4 to - 2 W/m2. High median radiative forcing effect values of about - 6 W/m2 were found to occur mainly in the summer months while lower values of about - 1 W/m2 occur in the winter months. The aerosol surface forcing also increases in summer months and can reach values of - 8 W/m2. Individual stations often have much higher values by a factor of 2. The median top-of-atmosphere aerosol radiative forcing effect efficiency is estimated to be about - 25 W/ m2 and their respective surface efficiency is around - 35 W/m2. The fractional absorption coefficient is estimated to be 1.7, but deviates significantly from station to station. In addition, it is found that the well known peak of the aerosol radiative forcing effect at a solar zenith angle of about 75° is in fact the average of the peaks occurring at shorter and longer wavelengths. According to estimations for Central Europe, based on mean aerosol optical properties retrievals from 12 stations, the critical threshold of the aerosol single scattering albedo, between cooling and heating in the presence of an aerosol layer, is close between 0.6 and 0.76. © Springer-Verlag 2006."
"14071914800;56179033200;56848611900;","Measurements of the HONO photodissociation constant",2006,"10.1007/s10874-006-9021-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747493037&doi=10.1007%2fs10874-006-9021-2&partnerID=40&md5=e47dc38e872c1783921b4996e6a3e92b","Measurements of the photodissociation constant for nitrous acid (jHONO) were made at an urban site in Toronto, Canada, during the months of May-July 2005, using an optically thin actinometer. Operating details of the jHONO monitor are reported, along with laboratory tests. Measurements of jHONO were obtained for solar zenith angles ranging from 20-75°, under clear and cloudy skies. Maximum error estimates on jHONO under clear skies range from 11% at sunrise, to 4% at solar noon, with a minimum detection limit of 5.7 × 10-4/sec for our actinometer. Measured clear-sky values of jHONO were compared with values calculated by a four-stream discrete ordinate radiative transfer (RT) model (ACD TUV version 4.1), and were found to be within better than 10% agreement for solar zenith angles <65°. For conditions of scattered cloud, enhancement and suppression of the jHONO values occurred by as much as 16%-70%, and 59%-80%, respectively. The integrated band area of the nπ* transition for gas-phase nitrous acid yields an oscillator strength, f = (1.06 ± 0.044) × 10-3 (based on clear-sky data), 19.1% higher than the value reported by Bongartz et al. (1991). © Springer Science+Business Media B.V. 2006."
"8875844200;","Surface energy balance errors in AGCMs: Implications for ocean-atmosphere model coupling",2005,"10.1029/2005GL023061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-25844475880&doi=10.1029%2f2005GL023061&partnerID=40&md5=7e845e4367cc68bb77a9ff989bb3b39b","The oceanic poleward heat transport (TO) implied by an atmospheric General Circulation Model (GCM) can help evaluate a model's readiness for coupling with an ocean GCM. A well known problem is that the sub-tropical Southern Hemisphere TO implied by many models is equatorward, contrary to most observationally-based estimates. By correcting the TO of a diversity of models with satellite-derived observations, an earlier study demonstrated that the dominant TO problems could be explained by model errors in cloud radiative effects. Such errors were argued to be primarily responsible for the erroneous Southern Hemisphere TO. However, systematic evaluation of one model in a later study suggested that the equatorward Southern Hemisphere TO might also be attributable to biases in the ocean surface latent heat flux. In this study we revisit the problem with a more recent suite of simulations, and demonstrate that collectively models have improved, but only slightly. We then use ocean surface fluxes estimates to examine the problem from a surface point of view. Our results clarify that common model errors in the surface latent heat flux can afflict TO as dramatically as errors in cloud radiative effects. To illustrate the relative importance of the two errors, diagnostic tests are introduced that should become increasingly useful as estimates of ocean surface fluxes are improved. Copyright 2005 by the American Geophysical Union."
"7202962414;7004899626;7202899330;","An assessment of the parameterization of subgrid-scale cloud effects on radiative transfer. Part II: Horizontal inhomogeneity",2005,"10.1175/JAS3498.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-26244450817&doi=10.1175%2fJAS3498.1&partnerID=40&md5=f01206a6422591935fb8154d9a278261","The role of horizontal inhomogeneity in radiative transfer through cloud fields is investigated within the context of the two-stream approximation. Spatial correlations between cloud optical properties and the radiance field are introduced in the three-dimensional radiative transfer equation and lead to a two-stream model in which the correlations are represented by parameterizations. The behavior of the model is examined using simple single-layer single-column atmospheres. Positive correlations between extinction or scattering and the radiance field are shown to decrease transmission, increase reflection, and increase absorption within inhomogeneous media. The parameterization is used to evaluate the characteristics of inhomogeneous cloud fields observed by radar and lidar over a number of different locations and seasons, revealing that shortwave transfer is generally characterized by negative correlations between extinction and radiance, while longwave transfer is characterized by positive correlations. The results from this characterization are applied to the integration of an atmospheric general circulation model. Model surface temperatures are significantly affected, largely in response to changes in downwelling radiative fluxes at the surface induced by changes in cloud cover and water vapor distributions. © 2005 American Meteorological Society."
"56627468800;7102223138;35512883100;","A finite element-spherical harmonics model for radiative transfer in inhomogeneous clouds Part I. The EVENT model",2004,"10.1016/j.atmosres.2004.03.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-8644268020&doi=10.1016%2fj.atmosres.2004.03.020&partnerID=40&md5=6a104716e881086d0ab355129bd8a1ed","We present a new numerical radiative transfer model for application to solar radiation transport in three-dimensional (3D) cloudy atmospheres. The code uses the finite element-spherical harmonics (FE- PN) approximation to solve the second-order even-parity form of the transport equation. It is validated by comparison with solutions from two well-established, deterministic radiative transfer models, the one-dimensional (1D) DISORT code and the spherical harmonics discrete ordinates method (SHDOM). The cases solved show generally good agreement, but also reveal some differences. EVEn-parity Neutral particle Transport (EVENT) is very efficient at performing 1D calculations quickly and, even for quite high angular resolutions, is faster. EVENT also has a competitive speed for the simpler, less-heterogeneous multidimensional cases but it is slower than SHDOM for more variable cases. However, there is significant potential to improve the performance of EVENT; it has not yet been optimised for speed and, as such, is not a finished product. Even as it is, EVENT could be used to produce fast, lower-resolution estimates for applications where this would be sufficient, or at lower-spatial resolutions with partial homogenisation. Another difference between the models is that the SHDOM algorithm is designed for small-scale inhomogeneous cloud fields in which the grid spacing is comparable to the mean free path. Problems arise from the use of larger grid cell optical depths, with an increase in the number of iterations required and a lack of flux conservation. Neither of the models is specifically constrained to conserve flux, but the conservation of flux gives an indication of the accuracy of the solution. Increasing the spatial and angular resolution can improve the accuracy but this is not always possible for very large 3D scenes. The grid-point method of property definition in SHDOM means that it performs best for cases with a continuous variation in extinction as this avoids discontinuities in the source function. The finite clouds used in our tests have sharp boundaries that are easily defined in EVENT but the difficulties caused by these in SHDOM are evident in excesses of up to 10 fluxes. The EVENT mesh resolution is determined by the local optical depth; it has no problem in dense areas but has more trouble in coping with voids or optically thin regions. These conditions are easily handled in SHDOM through streaming of photons along discrete ordinates but EVENT must implement methods such as a ray-tracing algorithm. Cases with extreme values of the extinction coefficient are probably best avoided with EVENT, but slightly larger-scale cases with greater optical depths, not suitable for SHDOM, may be solved more easily. These factors should be considered when selecting the most appropriate method for a particular application. © 2004 Elsevier B.V. All rights reserved."
"7201796620;7501757094;57208346904;57212815233;","Global and seasonal variations of O3 and NO2 photodissociation rate coefficients",2003,"10.1029/2002jd002760","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346461683&doi=10.1029%2f2002jd002760&partnerID=40&md5=ec068e074431273a56ff0d79df164507","The global and seasonal variations in the photodissociation rate coefficients (J values) of the reactions of ozone forming O(1D) (J(O1D)) and nitrogen dioxide forming O(3P) (J(NO2)) were investigated systematically with a focus on the troposphere. The corresponding mechanisms were studied through sensitivity modeling experiments of temperature, surface albedo, aerosols, ozone column, and clouds. The one-dimensional radiative transfer model PHODIS was applied with Total Ozone Mapping Spectrometer (TOMS) aerosol optical depth and surface reflectivity, observation-based three-dimensional ozone distributions, and other numerically simulated climate variables. Our results showed that under clear-sky conditions, the zonal averaged J(O1D) and J(NO2) peaked in magnitude at 3 × 10-5 and 8 × 10-3 s-1, respectively, in the region of 30°S to 30°N with small latitudinal and vertical variations, and decreased precipitously at 30°/60° in the winter/summer hemisphere. J(O1D) exhibited a large meridional and vertical gradient as a result of high sensitivity to temperature and ozone. The predominant effect of surface albedo led to significant longitudinal variation in J(NO2) and a poleward increase beyond 60° of the summer hemisphere. Surface J(O1D) changes were regressed as a second-degree polynomial function of changes in temperature (±20°K). The impact of low and middle clouds on J values was stronger than high clouds by a factor of 2 to 3 because of thick optical depth. In addition, the cloud-induced changes in J values calculated by PHODIS differed by up to 20% from those parameterized in the Regional Acid Deposition Model (RADM) and Intermediate Model for the Global and Annual Evolution of Species (IMAGES). Regional photochemical model simulations showed that an arbitrary increase/decrease of 20% above/below the cloud base (750 m) in J(O1D) resulted in decreases up to 6% in the ozone concentration below 200 m at noon and late afternoon and increases ubiquitously elsewhere."
"7201844203;7403497924;7402521017;","A sea surface radiation data set for climate applications in the tropical western Pacific and South China Sea",2001,"10.1029/2000JD900661","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034957372&doi=10.1029%2f2000JD900661&partnerID=40&md5=9fceee7c7416577b79d7589f62a86215","The sea surface shortwave and longwave radiative fluxes have been retrieved from the radiances measured by Japan's Geostationary Meteorological Satellite 5. The surface radiation data set covers the domain 40° S-40° N and 90° E-170° W and a period starting from January 1998. The temporal resolution is 1 day, and the spatial resolution is 0.5°×0.5° latitude-longitude. The retrieved surface radiation has been validated with the radiometric measurements at the Atmospheric Radiation Measurement (ARM) site on Manus Island in the equatorial western Pacific. It has also been validated with the measurements at the radiation site on Dungsha Island during the South China Sea Monsoon Experiment (SCSMEX) (May and June 1998). The data set is used to study the effect of El Nino and East Asian summer monsoon on the heating of the ocean. Interannual variations of clouds associated with El Nino and the East Asian summer monsoon have a large impact on the radiative heating of the ocean, exceeding 40 W m-2 in seasonal mean over large areas. Together with the Clouds and the Earth's Radiant Energy System (CERES) shortwave fluxes at the top of the atmosphere and the radiative transfer calculations of clear-sky fluxes, this surface radiation data set is also used to study the impact of clouds on the solar heating of the atmosphere. It is found that clouds enhance the atmospheric solar heating by ∼21 W m-2 in the tropical western Pacific and the South China Sea. Copyright 2001 by the American Geophysical Union."
"7405367162;7005070958;","Validation of longwave atmospheric radiation models using Atmospheric Radiation Measurement data",2000,"10.1029/2000JD900557","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034450371&doi=10.1029%2f2000JD900557&partnerID=40&md5=d2efa96bab2ad885a090d5619978aa42","Data taken at the Atmospheric Radiation Measurement Program's central facility in Oklahoma and processed as part of the Clouds and the Earth's Radiant Energy System-Atmospheric Radiation Measurement-Global Energy and Water Cycle Experiment (CAGEX) project have been used to validate the top-of-the-atmosphere and surface longwave radiative fluxes for two widely used radiation models: the Column Radiation Model from the National Center for Atmospheric Research Community Climate Model (CCM), and the Moderate Resolution Transmittance (MODTRAN3) radiation code. The results show that for clear skies the models slightly overestimate outgoing longwave radiation at the top of the atmosphere (OLR) and underestimate the surface downwelling longwave flux (SDLW). The accuracy of the radiation models is quite consistent with their respective levels of complexity. For MODTRAN3, for example, the OLR overestimate is 7.1 Wm-2 while the SDLW underestimate is 4.2 Wm-2. For cloudy skies it is emphasized that the cloud input parameters, as determined from measurements by various instruments, require careful examination and preprocessing. Spatial and temporal averaging could result in the parameters representing different volumes of the atmosphere. The discrepancy between model calculations and observations is shown to be significantly reduced through the proper choice of input parameters. Copyright 2000 by the American Geophysical Union."
"56520921400;6602991061;7003468747;7006246996;7006239404;7201646465;8266297500;","Determination of surface heating by convective cloud systems in the central equatorial Pacific from surface and satellite measurements",2000,"10.1029/2000JD900109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033788938&doi=10.1029%2f2000JD900109&partnerID=40&md5=a3eabb4a33ff3c35abfcd8450470b5de","The heating of the ocean surface by longwave radiation from convective clouds has been estimated using measurements from the Central Equatorial Pacific Experiment (CEPEX). The ratio of the surface longwave cloud forcing to the cloud radiative forcing on the total atmospheric column is parameterized by the f factor. The f factor is a measure of the partitioning of the cloud radiative effect between the surface and the troposphere. Estimates of the f factor have been obtained by combining simultaneous observations from ship, aircraft, and satellite instruments. The cloud forcing near the ocean surface is determined from radiometers on board the National Oceanic and Atmospheric Administration P-3 aircraft and the R/V John Vickers. The longwave cloud forcing at the top of the atmosphere has been estimated from data obtained from the Japanese Geostationary Meteorological Satellite GMS 4. A new method for estimating longwave fluxes from satellite narrowband radiances is described. The method is based upon calibrating the satellite radiances against narrowband and broadband infrared measurements from the high-altitude NASA ER-2 aircraft. The average value of f derived from the surface and satellite observations of convective clouds is 0.15 ± 0.02. The area-mean top-of-atmosphere longwave forcing by convective clouds in the region 10° S-10° N, 160° E-160° W is 40 W/m2 during CEPEX. These results indicate that the surface longwave forcing by convective clouds was approximately 5 W/m2 in the central equatorial Pacific and that this forcing is the smallest radiative component of the surface energy budget. Copyright 2000 by the American Geophysical Union."
"7003536279;7003728829;7005956183;36785976300;","Investigations of cloud layer base and top heights from 95 GHz radar reflectivity data",1999,"10.1016/S1464-1909(98)00032-X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032858551&doi=10.1016%2fS1464-1909%2898%2900032-X&partnerID=40&md5=e1d7a5d40eac571955f4eae54b8ab4d8","Cloud radars operating at millimeter wavelengths have proven to be invaluable for studying the 3-dimensional distribution of stratiform clouds. An improved knowledge of the occurrence of multiple cloud layers as well as of heights of their upper and lower boundaries is important for the determination of radiative fluxes with a higher accuracy. In this study measurements with the 95 GHz radar of GKSS Research Centre, Geesthacht, are used to determine base and top heights of layers of different cloud types. However, an accurate retrieval of cloud boundaries by remote sensors is not obvious, e.g., it is known that simultaneous measurements of the radar and backscatter lidars often show significant differences in cloud base heights. Reasons for inaccuracies in the determination of cloud boundary heights are discussed. Possibilities for corrections are illustrated that will finally lead to more reliable cloud boundary statistics necessary to improve radiative transfer calculations within large-scale weather forecasting and climate models."
"54409718800;57211542049;8505418900;57211531548;56888217500;6506666311;7006970286;7102020573;7005973015;","Constraining the vertical distribution of coastal dust aerosol using OCO-2 O2 A-band measurements",2020,"10.1016/j.rse.2019.111494","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074340646&doi=10.1016%2fj.rse.2019.111494&partnerID=40&md5=42846391e65c6c7f9f0e16545de6f8d9","Quantifying the vertical distribution of atmospheric aerosols is crucial for estimating their impact on the Earth's energy budget and climate, improving forecast of air pollution in cities, and reducing biases in the retrieval of greenhouse gases (GHGs) from space. However, to date, passive remote sensing measurements have provided limited information about aerosol extinction profiles. In this study, we propose the use of a spectral sorting approach to constrain the aerosol vertical structure using spectra of reflected sunlight absorption within the molecular oxygen (O2) A-band collected by the Orbiting Carbon Observatory-2 (OCO-2). The effectiveness of the approach is evaluated using spectra acquired over the western Sahara coast by comparing the aerosol profile retrievals with lidar measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Using a radiative transfer model to simulate OCO-2 measurements, we found that high-resolution O2 A-band measurements have high sensitivity to aerosol optical depth (AOD) and aerosol layer height (ALH). Retrieved estimates of AOD and ALH based on a look up table technique show good agreement with CALIPSO measurements, with correlation coefficients of 0.65 and 0.53, respectively. The strength of the proposed spectral sorting technique lies in its ability to identify spectral channels with high sensitivity to AOD and ALH and extract the associated information from the observed radiance in a straightforward manner. The proposed approach has the potential to enable future passive remote sensing missions to map the aerosol vertical distribution on a global scale. © 2019 Elsevier Inc."
"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)."
"23492864500;6603566335;","Boundary Layer Clouds and Convection over Subtropical Oceans in our Current and in a Warmer Climate",2019,"10.1007/s40641-019-00126-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065421570&doi=10.1007%2fs40641-019-00126-x&partnerID=40&md5=6c07875bf284617d00ac375bbd5cffce","Purpose of Review: We review our understanding of mechanisms underlying the response of (sub)tropical clouds to global warming, highlight mechanisms that challenge our understanding, and discuss simulation strategies that tackle them. Recent Findings: Turbulence-resolving models and emergent constraints provide probable evidence, supported by theoretical understanding, that the cooling cloud radiative effect (CRE) of low clouds weakens with warming: a positive low-cloud feedback. Nevertheless, an uncertainty in the feedback remains. Climate models may not adequately represent changing SST and circulation patterns, which determine future cloud-controlling factors and how these couple to clouds. Furthermore, we do not understand what mesoscale organization implies for the CRE, and how moisture-radiation interactions, horizontal advection, and the profile of wind regulate low cloud, in our current and in our warmer climate. Summary: Clouds in nature are more complex than the idealized cloud types that have informed our understanding of the cloud feedback. Remaining major uncertainties are the coupling of clouds to large-scale circulations and to the ocean, and mesoscale aggregation of clouds. © 2019, The Author(s)."
"57192180109;35782476600;56250119900;7004587644;57211565887;55796882100;7103016965;24168416900;","Cluster-Based Evaluation of Model Compensating Errors: A Case Study of Cloud Radiative Effect in the Southern Ocean",2019,"10.1029/2018GL081686","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063565470&doi=10.1029%2f2018GL081686&partnerID=40&md5=480a5ba6877efecf090e9658dd1789b9","Model evaluation is difficult and generally relies on analysis that can mask compensating errors. This paper defines new metrics, using clusters generated from a machine learning algorithm, to estimate mean and compensating errors in different model runs. As a test case, we investigate the Southern Ocean shortwave radiative bias using clusters derived by applying self-organizing maps to satellite data. In particular, the effects of changing cloud phase parameterizations in the MetOffice Unified Model are examined. Differences in cluster properties show that the regional radiative biases are substantially different than the global bias, with two distinct regions identified within the Southern Ocean, each with a different signed bias. Changing cloud phase parameterizations can reduce errors at higher latitudes but increase errors at lower latitudes of the Southern Ocean. Ranking the parameterizations often shows a contrast in mean and compensating errors, notably in all cases large compensating errors remain. ©2019. American Geophysical Union. All Rights Reserved."
"55704350200;14020751800;57189294502;57202531041;","Remote sensing of cloud droplet radius profiles using solar reflectance from cloud sides - Part 1: Retrieval development and characterization",2019,"10.5194/amt-12-1183-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062233827&doi=10.5194%2famt-12-1183-2019&partnerID=40&md5=adb7fd4016be6f403172d8a1ffdabb64","Convective clouds play an essential role for Earth's climate as well as for regional weather events since they have a large influence on the radiation budget and the water cycle. In particular, cloud albedo and the formation of precipitation are influenced by aerosol particles within clouds. In order to improve the understanding of processes from aerosol activation, from cloud droplet growth to changes in cloud radiative properties, remote sensing techniques become more and more important. While passive retrievals for spaceborne observations have become sophisticated and commonplace for inferring cloud optical thickness and droplet size from cloud tops, profiles of droplet size have remained largely uncharted territory for passive remote sensing. In principle they could be derived from observations of cloud sides, but faced with the small-scale heterogeneity of cloud sides, ""classical"" passive remote sensing techniques are rendered inappropriate. In this work the feasibility is demonstrated to gain new insights into the vertical evolution of cloud droplet effective radius by using reflected solar radiation from cloud sides. Central aspect of this work on its path to a working cloud side retrieval is the analysis of the impact unknown cloud surface geometry has on effective radius retrievals. This study examines the sensitivity of reflected solar radiation to cloud droplet size, using extensive 3-D radiative transfer calculations on the basis of realistic droplet size resolving cloud simulations. Furthermore, it explores a further technique to resolve ambiguities caused by illumination and cloud geometry by considering the surroundings of each pixel. Based on these findings, a statistical approach is used to provide an effective radius retrieval. This statistical effective radius retrieval is focused on the liquid part of convective water clouds, e.g., cumulus mediocris, cumulus congestus, and trade-wind cumulus, which exhibit well-developed cloud sides. Finally, the developed retrieval is tested using known and unknown cloud side scenes to analyze its performance. © 2019. This work is distributed under the Creative Commons Attribution 4.0 License."
"56493740900;7102651635;25633865300;55942502100;24333241700;55695451700;6506827279;7406061582;57211010680;","Radiative Heating Rates Computed With Clouds Derived From Satellite-Based Passive and Active Sensors and their Effects on Generation of Available Potential Energy",2019,"10.1029/2018JD028878","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061240087&doi=10.1029%2f2018JD028878&partnerID=40&md5=fe2ee40686f3da592a55668b1178a143","Radiative heating rates computed with cloud properties derived from passive and active sensors are investigated. Zonal monthly radiative heating rate anomalies computed using both active and passive sensors show that larger variability in longwave cooling exists near the tropical tropopause and near the top of the boundary layer between ~50°N to ~50°S. Aerosol variability contributes to increases in shortwave heating rate variability. When zonal monthly mean cloud effects on the radiative heating rate computed with both active and passive sensors and those computed with passive sensor only are compared, the latter shows cooling and heating peaks corresponding to cloud top and base height ranges used for separating cloud types. The difference of these two sets of cloud radiative effect on heating rates in the middle to upper troposphere is larger than the radiative heating rate uncertainty estimated based on the difference of two active sensor radiative heating rate profile data products. In addition, radiative heating rate contribution to generation of eddy available potential energy is also investigated. Although radiation contribution to generation of eddy available potential energy averaged over a year and the entire globe is small, radiation increases the eddy available potential energy in the northern hemisphere during summer. Two key elements that longwave radiation contribute to the generation of eddy potential energy are (1) longitudinal temperature gradient in the atmosphere associated with land and ocean surface temperatures contrasts and absorption of longwave radiation emitted by the surface and (2) cooling near the cloud top of stratocumulus clouds. ©2018. The Authors."
"56628141500;6603196127;26667030700;7202079615;7403722047;36522733500;9249627300;6603378233;","Effect of high dust amount on surface temperature during the Last Glacial Maximum: A modelling study using MIROC-ESM",2018,"10.5194/cp-14-1565-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056379733&doi=10.5194%2fcp-14-1565-2018&partnerID=40&md5=53821c6cb7b88a981673fa9b7acf1fc1","The effect of aerosols is one of many uncertain factors in projections of future climate. However, the behaviour of mineral dust aerosols (dust) can be investigated within the context of past climate change. The Last Glacial Maximum (LGM) is known to have had enhanced dust deposition in comparison with the present, especially over polar regions. Using the Model for Interdisciplinary Research on Climate Earth System Model (MIROC-ESM), we conducted a standard LGM experiment following the protocol of the Paleoclimate Modelling Intercomparison Project phase 3 and sensitivity experiments. We imposed glaciogenic dust on the standard LGM experiment and investigated the impacts of glaciogenic dust and non-glaciogenic dust on the LGM climate. Global mean radiative perturbations by glaciogenic and non-glaciogenic dust were both negative, consistent with previous studies. However, glaciogenic dust behaved differently in specific regions; e.g. it resulted in less cooling over the polar regions. One of the major reasons for reduced cooling is the ageing of snow or ice, which results in albedo reduction via high dust deposition, especially near sources of high glaciogenic dust emission. Although the net radiative perturbations in the lee of high glaciogenic dust provenances are negative, warming by the ageing of snow overcomes this radiative perturbation in the Northern Hemisphere. In contrast, the radiative perturbation due to high dust loading in the troposphere acts to warm the surface in areas surrounding Antarctica, primarily via the longwave aerosol-cloud interaction of dust, and it is likely the result of the greenhouse effect attributable to the enhanced cloud fraction in the upper troposphere. Although our analysis focused mainly on the results of experiments using the atmospheric part of the MIROC-ESM, we also conducted full MIROC-ESM experiments for an initial examination of the effect of glaciogenic dust on the oceanic general circulation module. A long-term trend of enhanced warming was observed in the Northern Hemisphere with increased glaciogenic dust; however, the level of warming around Antarctica remained almost unchanged, even after extended coupling with the ocean. © 2018 Author(s)."
"57202078062;36678944300;35286080700;56073100500;57204355181;57193254488;56158622800;","The impacts of atmospheric and surface parameters on long-term variations in the planetary albedo",2018,"10.1175/JCLI-D-17-0848.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055272620&doi=10.1175%2fJCLI-D-17-0848.1&partnerID=40&md5=bb18fe3e5f9546ee74f3e172c60fd8d5","Planetary albedo (PA; shortwave broadband albedo) and its long-term variations, which are controlled in a complex way by various atmospheric and surface properties, play a key role in controlling the global and regional energy budget. This study investigates the contributions of different atmospheric and surface properties to the long-term variations of PA based on 13 years (2003-15) of albedo, cloud, and ice coverage datasets from the Clouds and the Earth's Radiant Energy System (CERES) Single Scanner Footprint edition 4A product, vegetation product from Moderate Resolution Imaging Spectroradiometer (MODIS), and surface albedo product from the Cloud, Albedo, and Radiation dataset, version 2 (CLARA-A2). According to the temporal correlation analysis, statistical results indicate that variations in PA are closely related to the variations of cloud properties (e.g., cloud fraction, ice water path, and liquid water path) and surface parameters (e.g., ice/snow percent coverage and normalized difference vegetation index), but their temporal relationships vary among the different regions. Generally, the stepwise multiple linear regression models can capture the observed PA anomalies for most regions. Based on the contribution calculation, cloud fraction dominates the variability of PA in the mid- and low latitudes while ice/snow percent coverage (or surface albedo) dominates the variability in the mid- and high latitudes. Changes in cloud liquid water path and ice water path are the secondary dominant factor over most regions, whereas change in vegetation cover is the least important factor over land. These results verify the effects of atmospheric and surface factors on planetary albedo changes and thus may be of benefit for improving the parameterization of the PA and determining the climate feedbacks. © 2018 American Meteorological Society."
"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."
"25931139100;56123889200;6701481007;35546188200;6602176524;23017945100;","Potential of microwave observations for the evaluation of rainfall and convection in a regional climate model in the frame of HyMeX and MED-CORDEX",2018,"10.1007/s00382-016-3203-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044481577&doi=10.1007%2fs00382-016-3203-7&partnerID=40&md5=6b91138a7daf00ca2298e1c7d6f7d3e3","This study evaluates the potential of spaceborne passive microwave observations for assessing decadal simulations of precipitation from a regional climate model through a model-to-satellite approach. A simulation from the Weather and Research Forecasting model is evaluated against 2002–2012 observations from the Advanced Microwave Sounding Unit and the Microwave Humidity Sounder over the Mediterranean region using the radiative transfer code Radiative Transfer for Tiros Operational Vertical Sounder. It is first shown that simulated and observed brightness temperatures are consistently correlated for both water vapour and window channels. Yet, although the average simulated and observed brightness temperatures are similar, the range of brightness temperatures is larger in the observations. The difference is presumably due to the too low content of frozen particles in the simulation. To assess this hypothesis, density and altitude of simulated frozen hydrometeors are compared with observations from an airborne cloud radar. Results show that simulated frozen hydrometeors are found at lower median altitude than observed frozen hydrometeors, with an average content at least 5 times inferior. Spatial distributions of observed and simulated precipitation match reasonably well. However, when using simulated brightness temperatures to diagnose rainfall, the simulation performs very poorly. These results highlight the need of providing more realistic frozen hydrometeors content, which will increase the interest of using passive microwave observations for the long-term evaluation of regional models. In particular, significant improvements are expected from the archiving of convective fluxes of precipitating hydrometeors in future regional model simulation programs. © 2016, Springer-Verlag Berlin Heidelberg."
"8548304600;8836278700;57199920061;15846270900;36609311400;40761390100;57195931940;","Scavenging ratio of black carbon in the Arctic and the Antarctic",2018,"10.1016/j.polar.2018.03.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044863097&doi=10.1016%2fj.polar.2018.03.002&partnerID=40&md5=eca7db2d71aa0373a480ce988df43567","Long-term monitoring of atmospheric aerosols and their interaction with radiation, cloud, and cryosphere over the Arctic and the Antarctic are very important for the global climate change related issues. In this regard, for conducting aerosol measurements, India has extended the concerted efforts to the Svalbard region of the Norwegian Arctic (Himadri, 78°55′N 11°56′E, 8 m a.s.l.) in the northern hemisphere and the Larsemann Hills of coastal Antarctic (Bharati, 69°24.4′S 76°11.7′E, 40 m a.s.l.) in the southern hemisphere. In the present study, we have examined the role of black carbon (BC) deposition in darkening the polar snow in different sunlit seasons and estimated the scavenging ratio of BC over both the poles from simultaneous measurements of atmospheric and snow deposited BC concentrations. The study reveals distinct spatio-temporal variability of BC in polar snow, even though the concentrations are, in general, low (<12 ppbw, parts per billion by weight). During local summer seasons, the BC in snow at the Arctic (median ∼ 7.98 ppbw) was higher than that at the Antarctica (median ∼ 1.70 ppbw). Concurrent with this, the scavenging ratio (SR) also showed large variability over both the poles. Relatively higher values of SR over the Antarctica (mean ∼ 119.54 ± 23.04; during southern hemispheric summer) in comparison to that over the Arctic (mean ∼ 69.48 ± 4.79; during northern hemispheric spring) clearly indicate the difference in removal mechanisms (aerosol mixing, aging and size distribution) of BC from the atmosphere over distinct polar environments. Measurement of spectral incoming and reflected radiances over the Arctic snow during the early spring season of 2017 indicated the values of surface broadband albedo varying between 0.64 and 0.79. The Snow, Ice and Aerosol Radiative (SNICAR) model simulated values of spectral albedo correlated well with the measured ones and indicated the role of dust absorption, in addition to that of BC, in changing the snow albedo. This information needs to be accurately incorporated in the radiative transfer models for the accurate estimation of snow albedo forcing over the Polar Regions. © 2018 Elsevier B.V. and NIPR"
"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."
"22982141200;57194228945;55731174900;57203321797;","Diurnal temperature range in CMIP5 models and observations on the Tibetan Plateau",2017,"10.1002/qj.3057","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019358110&doi=10.1002%2fqj.3057&partnerID=40&md5=25c6b184ce63524fbe9d4d25be86941e","The diurnal temperature range (DTR), defined as the difference between the maximum and minimum temperature, is a useful diagnostic index for evaluating global climate models. In this study, the DTR from 17 GCMs available in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) is evaluated on the Tibetan Plateau (TP) by comparison with the observations during 1961–2005. During the studied period, the observed maximum/minimum temperatures on the TP show statistically increasing trends with the annual rates of 0.19/0.36 °C decade−1, respectively, leading to the reduction of DTR (−0.22 °C decade−1). Compared with the observed DTR, most CMIP5 models generally underestimate DTR, with absolute error ranging from −4.58 °C (GFDL-ESM2M) to −1.36 °C (CESM1-BGC). Fifteen CMIP5 models have reproduced the overall negative trends of DTR on the TP, but their trend magnitudes are smaller. Furthermore, the CMIP5 model biases in DTR are investigated by means of correlative approach, to reveal the dominant variables. The differences between the surface downwelling short-wave radiation (SDSR) with clear skies (SDSRcs) and the SDSR can be used to describe the surface short-wave cloud radiative effect. Similarly, the differences between the surface downwelling long-wave radiation (SDLR) and the SDLR with clear skies (SDLRcs) are defined to address the surface long-wave cloud radiative effect. It is found that the mean DTR in the CMIP5 models has significantly negative correlations with both SDLR–SDLRcs and SDSRcs–SDSR, suggesting that the model differences in DTR on the TP are probably determined by radiation variables and total cloud fraction in the CMIP5 models. © 2017 Royal Meteorological Society"
"55703069400;56279208100;7102963655;","Characterisation of Special Sensor Microwave Water Vapor Profiler (SSM/T-2) radiances using radiative transfer simulations from global atmospheric reanalyses",2017,"10.1016/j.asr.2016.11.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008173385&doi=10.1016%2fj.asr.2016.11.017&partnerID=40&md5=e265b04f180d04fff5947d208754cc0c","The near-global and all-sky coverage of satellite observations from microwave humidity sounders operating in the 183 GHz band complement radiosonde and aircraft observations and satellite infrared clear-sky observations. The Special Sensor Microwave Water Vapor Profiler (SSM/T-2) of the Defense Meteorological Satellite Program began operations late 1991. It has been followed by several other microwave humidity sounders, continuing today. However, expertise and accrued knowledge regarding the SSM/T-2 data record is limited because it has remained underused for climate applications and reanalyses. In this study, SSM/T-2 radiances are characterised using several global atmospheric reanalyses. The European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis (ERA-Interim), the first ECMWF reanalysis of the 20th-century (ERA-20C), and the Japanese 55-year Reanalysis (JRA-55) are projected into SSM/T-2 radiance space using a fast radiative transfer model. The present study confirms earlier indications that the polarisation state of SSM/T-2 antenna is horizontal (not vertical) in the limit of nadir viewing. The study also formulates several recommendations to improve use of the SSM/T-2 measurement data in future fundamental climate data records or reanalyses. Recommendations are (1) to correct geolocation errors, especially for DMSP 14; (2) to blacklist poor quality data identified in the paper; (3) to correct for inter-satellite biases, estimated here on the order of 1 K, by applying an inter-satellite recalibration or, for reanalysis, an automated (e.g., variational) bias correction; and (4) to improve precipitating cloud filtering or, for reanalysis, consider an all-sky assimilation scheme where radiative transfer simulations account for the scattering effect of hydrometeors. © 2016"
"30667558200;13403622000;","Improving climate projections by understanding how cloud phase affects radiation",2017,"10.1002/2017JD026927","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018414003&doi=10.1002%2f2017JD026927&partnerID=40&md5=1742d66001dffeb6760b4ff2d91be3b2","Whether a cloud is predominantly water or ice strongly influences interactions between clouds and radiation coming down from the Sun or up from the Earth. Being able to simulate cloud phase transitions accurately in climate models based on observational data sets is critical in order to improve confidence in climate projections, because this uncertainty contributes greatly to the overall uncertainty associated with cloud-climate feedbacks. Ultimately, it translates into uncertainties in Earth’s sensitivity to higher CO2 levels. While a lot of effort has recently been made toward constraining cloud phase in climate models, more remains to be done to document the radiative properties of clouds according to their phase. Here we discuss the added value of a new satellite data set that advances the field by providing estimates of the cloud radiative effect as a function of cloud phase and the implications for climate projections. © 2017. American Geophysical Union."
"57188745140;57196143493;55675283100;6506385754;55926866400;24554163500;57206166579;55656837900;","An assessment of the radiative effects of ice supersaturation based on in situ observations",2016,"10.1002/2016GL071144","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995578211&doi=10.1002%2f2016GL071144&partnerID=40&md5=8191a4485f6d0ad84b828f287fb86a2a","We use aircraft observations combined with the reanalysis data to investigate the radiative effects of ice supersaturation (ISS). Our results show that although the excess water vapor over ice saturation itself has relatively small radiative effects, mistaking it as ice crystals in climate models would lead to considerable impacts: on average, +2.49 W/m2 change in the top of the atmosphere (TOA) radiation, −2.7 W/m2 change in surface radiation, and 1.47 K/d change in heating rates. The radiative effects of ISS generally increase with the magnitudes of supersaturation. However, there is a strong dependence on the preexisting ice water path, which can even change the sign of the TOA radiative effect. It is therefore important to consider coexistence between ISS and ice clouds and to validate their relationship in the parameterizations of ISS in climate models. ©2016. American Geophysical Union. All Rights Reserved."
"55469523400;15124698700;","Scaling of the entropy budget with surface temperature in radiative-convective equilibrium",2016,"10.1002/2016MS000673","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979735717&doi=10.1002%2f2016MS000673&partnerID=40&md5=0c627f56c07fe9e7ce9ba554fe545afb","The entropy budget of the atmosphere is examined in simulations of radiative-convective equilibrium with a cloud-system resolving model over a wide range of surface temperatures from 281 to 311 K. Irreversible phase changes and the diffusion of water vapor account for more than half of the irreversible entropy production within the atmosphere, even in the coldest simulation. As the surface temperature is increased, the atmospheric radiative cooling rate increases, driving a greater entropy sink that must be matched by greater irreversible entropy production. The entropy production resulting from irreversible moist processes increases at a similar fractional rate as the entropy sink and at a lower rate than that implied by Clausius-Clapeyron scaling. This allows the entropy production from frictional drag on hydrometeors and on the atmospheric flow to also increase with warming, in contrast to recent results for simulations with global climate models in which the work output decreases with warming. A set of approximate scaling relations is introduced for the terms in the entropy budget as the surface temperature is varied, and many of the terms are found to scale with the mean surface precipitation rate. The entropy budget provides some insight into changes in frictional dissipation in response to warming or changes in model resolution, but it is argued that frictional dissipation is not closely linked to other measures of convective vigor. © 2016. The Authors."
"55704388300;24281186100;7403221533;6602185497;","Effects of clouds on the surface shortwave radiation at a rural inland mid-latitude site",2016,"10.1016/j.atmosres.2016.03.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962762855&doi=10.1016%2fj.atmosres.2016.03.020&partnerID=40&md5=179bfa7990476daac318d9a77bfeed5c","Seven years (2003-2010) of measured shortwave (SW) irradiances were used to obtain estimates of the 10 min averaged effective cloud optical thickness (ECOT) and of the shortwave cloud radiative effect (CRESW) at the surface in a mid-latitude site (Évora - south of Portugal), and its seasonal variability is presented. The ECOT, obtained using transmittance measurements at 415 nm, was compared with the correspondent MODIS cloud optical thickness (MODIS COT) for non-precipitating water clouds and cloud fractions higher than 0.25. This comparison showed that the ECOT represents well the cloud optical thickness over the study area. The CRESW, determined for two SW broadband ranges (300-1100 nm; 285-2800 nm), was normalized (NCRESW) and related with the obtained ECOT. A logarithmic relation between NCRESW and ECOT was found for both SW ranges, presenting lower dispersion for overcast-sky situations than for partially cloudy-sky situations. The NCRESW efficiency (NCRESW per unit of ECOT) was also related with the ECOT for overcast-sky conditions. The relation found is parameterized by a power law function showing that NCRESW efficiency decreases as the ECOT increases, approaching one for ECOT values higher than about 50. © 2016 Elsevier B.V."
"7403625607;7403180902;","An initial study on climate change fingerprinting using the reflected solar spectra",2016,"10.1175/JCLI-D-15-0297.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964856458&doi=10.1175%2fJCLI-D-15-0297.1&partnerID=40&md5=073693e74f731576aa6fb721d6266477","Attribution of averaged spectral variation over large spatial and temporal scales to different climate variables is central to climate change fingerprinting. Using 10 years of satellite data for simulation, the authors generate a group of observation-based spectral fingerprints and a time series of monthly mean reflectance spectra over the ocean in five large latitude regions and globally. Next, these fingerprints and the interannual variation spectra are used to retrieve the interannual changes in the relevant climate variables to test the concept of using the spectral fingerprinting approach for climate change attribution. Comparing the fingerprinting retrieval of climate variable change to the actual underlying variable change, the RMS differences between the two are less than twice as large as the monthly variability for all variables in all regions. Instances where larger errors are observed correspond to those variables with large nonlinear radiative response, such as the cloud optical depth and the ice particle size. Using the linear fingerprinting approach and accounting for the nonlinear radiative error in fingerprints results in significantly higher retrieval accuracy; the RMS errors are reduced to less than the monthly variability for nearly all variables, indicating the profound impact of the nonlinear error on fingerprinting retrieval. Another important finding is that if the cloud fraction is known a priori, the retrieval accuracy in cloud optical depth would be improved substantially. Moreover, a better retrieval for the water vapor amount and aerosol optical depth can be achieved from the clear-sky data only. The test results demonstrate that climate change fingerprinting based on reflected solar benchmark spectra is possible. © 2016 American Meteorological Society."
"56763174500;55745955800;7401936984;","An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5",2016,"10.1002/2015JD024167","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958729688&doi=10.1002%2f2015JD024167&partnerID=40&md5=d0f8d44b0f516e2a8ee35e8fa6c56143","Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models (e.g., large eddy simulations, cloud-resolving models, and single column models (SCMs)) that are used to develop physical parameterizations in global climate models. This study introduces an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix, and constraint variables are presented to quantify the uncertainties in the large-scale forcing data and state variables. Application of the ensemble forcing in the CAM5 SCM during March 2000 intensive operational period at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement Program shows that the systematic biases in the model simulations (i.e., excessive high clouds and insufficient low clouds) cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data over the surrounding SGP site for annual and seasonal means. © 2015. The Authors."
"55427545900;7004540083;","Cloud radiative effects and precipitation in extratropical cyclones",2016,"10.1175/JCLI-D-15-0857.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987934999&doi=10.1175%2fJCLI-D-15-0857.1&partnerID=40&md5=64c460b411f3f5f3cc8b74161ba8f7a4","Clouds associated with extratropical cyclones complicate the well-developed theory of dry baroclinic waves through feedback on their dynamics by precipitation and cloud-altered radiative heating. The relationships between cyclone characteristics and the diabatic heating associated with cloud radiative effects (CREs) and latent heat release remain unclear. A cyclone tracking algorithm [NASA's Modeling, Analysis, and Prediction (MAP) Climatology of Midlatitude Storminess (MCMS)] is used to identify over 106 cyclones in 33 years of the ERA-Interim and collect the properties of each disturbance. Considering storm intensity as related to wind speeds, which depend on the pressure gradient, the distribution of cyclone properties is investigated using groups defined by their depth (local pressure anomaly) and the radius of the region within closed pressure contours to investigate variations with longitude (especially ocean and land), hemisphere, and season. Using global data products of cloud radiative effects on in-atmosphere net radiation [the ISCCP radiative flux profile dataset (ISCCP-FD)] and precipitation (GPCP), composites are assembled for each cyclone group and for ""nonstormy"" locations. On average, the precipitation rate and the CRE are approximately the same among all cyclone groups and do not strongly differ from nonstormy conditions. The variance of both precipitation and CRE increases with cyclone size and depth. In larger, deeper storms, maximum precipitation and CRE increase, but so do the amounts of nonprecipitating and clear-sky conditions. © 2016 American Meteorological Society."
"57022402900;7402989545;55701363700;","Quantifying contributions of model processes to the surface temperature bias in FGOALS-g2",2015,"10.1002/2015MS000459","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959463858&doi=10.1002%2f2015MS000459&partnerID=40&md5=fe1a5ab1d4d2452010a73387979d2fa5","To quantify the annual mean surface temperature bias due to various processes in Flexible Global Ocean-Atmosphere-Land-System model, Grid point version 2 (FGOALS-g2), the climate feedback-response analysis method (CFRAM) is used to isolate contributions from both radiative and nonradiative processes in the model by comparing the model simulation with ERA-Interim reanalysis. The observed surface temperature bias is decomposed into seven partial temperature biases associated with surface albedo, water vapor, cloud, both surface sensible and latent heat fluxes, land/ocean heat transport processes, and atmospheric transport processes. The global mean cold bias (-1.39 K) is mostly attributed to surface albedo and land/ocean heat transport processes while surface latent heat fluxes tend to weaken this bias. Cloud-induced bias is dominated by shortwave cloud radiative effect (SWCRE) over low-latitudes and longwave cloud radiative effect (LWCRE) over high latitudes. The mixed layer depth (MLD) bias is consistent with the bias due to ocean heat transport over North Pacific, North Atlantic, and the Southern Ocean. On global scale, contributions of radiative processes and nonradiative processes to the total observed cold bias are comparable, but tend to compensate each other over most regions except for the northern high latitudes. We suggest that the improvements in tropical clouds in the model may significantly decrease the global temperature bias through the interaction between clouds and circulation. © 2015. The Authors. Journal of Advances in Modeling Earth Systems published by Wiley Periodicals, Inc."
"55372257600;7004364155;","On the relative stability of CERES reflected shortwave and MISR and MODIS visible radiance measurements during the terra satellite mission",2015,"10.1002/2015JD023484","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955198110&doi=10.1002%2f2015JD023484&partnerID=40&md5=5f262b48d43b63d97ee1b38713642db8","Fifteen years of visible, near-infrared, and broadband shortwave radiance measurements from Clouds and the Earth’s Radiant Energy System (CERES), Multiangle Imaging Spectroradiometer (MISR), and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board NASA’s Terra satellite are analyzed in order to assess their long-term relative stability for climate purposes. A regression-based approach between CERES, MODIS, and MISR (An camera only) reflectances is used to calculate the bias between the different reflectances relative to a reference year. When compared to the CERES shortwave broadband reflectance, relative drift between the MISR narrowbands is within 1% decade−1. Compared to the CERES shortwave reflectance, the MODIS narrowband reflectances show a relative drift of less than −1.33% decade−1. When compared to MISR, the MODIS reflectances show a relative drift of between −0.36% decade−1 and −2.66% decade−1. We show that the CERES Terra SW measurements are stable over the time period relative to CERES Aqua. Using this as evidence that CERES Terra may be absolutely stable, we suggest that the CERES, MISR, and MODIS instruments meet the radiometric stability goals for climate applications set out in Ohring et al. (2005). © 2015. American Geophysical Union. All Rights Reserved."
"55967435100;35209683700;","Initial transient response of an intensifying baroclinic wave to increases in cloud droplet number concentration",2015,"10.1175/JCLI-D-15-0251.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957692612&doi=10.1175%2fJCLI-D-15-0251.1&partnerID=40&md5=834830eb6f37a615e6add1bce6988ad5","Ensemble simulations of an idealized baroclinic wave were conducted with the WRF Model to investigate the effects of increased cloud droplet number concentration (DNC) on the development of the wave. Statistically significant differences between experiments where the DNC was doubled and the control experiments were identified for an initial transient period before the cyclone enters the stage of rapid intensification. Doubling of the DNC increases total cloud water in the model, lowers the cloud level, and enhances latent heating to the east of the surface low, which strengthens the midtropospheric ridge. Subsequent changes in dry dynamical processes [e.g., advection of potential vorticity (PV)] as a result of the ridge strengthening lead to the deepening of the trough and ultimately produce a mild yet statistically significant strengthening of the baroclinic wave as a result of the DNC doubling. Piecewise PV inversion further confirms the critical role that latent heating change plays in strengthening the midtropospheric ridge. Also discussed are the distinctions between aerosol-tropical cyclone interaction and aerosol-extratropical cyclone interaction. © 2015 American Meteorological Society."
"36634069800;7405489798;7402064802;22635190100;","Low-cloud characteristics over the tropical western Pacific from ARM observations and CAM5 simulations",2015,"10.1002/2015JD023369","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943453997&doi=10.1002%2f2015JD023369&partnerID=40&md5=f9dff08902cf67b438059fdd94365dce","This study evaluates the ability of the Community Atmospheric Model version 5 (CAM5) to reproduce low clouds observed by the Atmospheric Radiation Measurement (ARM) cloud radar at Manus Island of the tropical western Pacific during the Years of Tropical Convection. Here low clouds are defined as clouds with their tops below the freezing level and bases within the boundary layer. Low-cloud statistics in CAM5 simulations and ARM observations are compared in terms of their general occurrence, mean vertical profiles, fraction of precipitating versus nonprecipitating events, diurnal cycle, and monthly time series. Other types of clouds are included to put the comparison in a broader context. The comparison shows that the model overproduces total clouds and their precipitation fraction but underestimates low clouds in general. The model, however, produces excessive low clouds in a thin layer between 954 and 930 hPa, which coincides with excessive humidity near the top of the mixed layer. This suggests that the erroneously excessive low clouds stem from parameterization of both cloud and turbulence mixing. The model also fails to produce the observed diurnal cycle in low clouds, not exclusively due to the model coarse grid spacing that does not resolve Manus Island. This study demonstrates the utility of ARM long-term cloud observations in the tropical western Pacific in verifying low clouds simulated by global climate models, illustrates issues of using ARM observations in model validation, and provides an example of severe model biases in producing observed low clouds in the tropical western Pacific. © 2015. American Geophysical Union. All Rights Reserved."
"55233910100;9233714800;54789102700;7403937350;","UV sensitivity to changes in ozone, aerosols, and clouds in Seoul, South Korea",2014,"10.1175/JAMC-D-13-052.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897586685&doi=10.1175%2fJAMC-D-13-052.1&partnerID=40&md5=88cd35a8774a0e99ca577f178abd5ab5","The total ozone (O3) and aerosol optical depth (AOD) at 320 nm have been observed from the ultraviolet (UV) measurements made at Yonsei University in Seoul, South Korea, with Dobson and Brewer spectrophotometers, respectively, during 2004-10. The daily datasets are analyzed to show the sensitivities of UV radiation to changes in O3, AOD, and cloud cover (CC) together with global solar radiation (GS), including the long-term characteristics of surface UV irradiance in Seoul. The UV sensitivities show that 1% increases of O3 and AOD relative to their reference values under all- and clear-sky conditions similarly manifest as 1-1.2% and 0.2% decreases of both daily erythemal UV (EUV) and total UV (TUV) irradiance at the ground level except for TUV sensitivity to O3 (~0.3%). Those UV sensitivities to CC and GS changes are associated with a 0.12% decrease and 0.7% increase, respectively, in fractional UV changes. The trends show that the positive trends of O3 (+7.2% decade-1), AOD (+22.4% decade-1), and CC (+52.4% decade-1) induce negative trends in EUV (-8.4% decade-1) and TUV (-2.5% decade-1), in both UV (-4.7% decade-1), and in EUV (-6.3% decade-1) and TUV (-6.8% decade-1), respectively. On the basis of the multiple linear regression analyses, it is found that UV sensitivity to O3 is relatively high in the forcing factors, but the contributions of the UV forcing factors to the daily variability and the range of UV disturbances due to the variability of the forcing factors are affected more by AOD than by O3 and CC in both UV fractional changes. © 2014 American Meteorological Society."
"25941200000;8397494800;7101815213;","Estimation of errors associated with the EarthCARE 3D scene construction algorithm",2014,"10.1002/qj.2294","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84922839584&doi=10.1002%2fqj.2294&partnerID=40&md5=deacc541e991cdb719fca6eb69a72227","The EarthCARE satellite mission plans to perform a continuous closure experiment to assess the quality of retrieved cloud and aerosol properties. It will do so by comparing top-of-atmosphere (TOA) broad-band (BB) fluxes with simulated values produced by three-dimensional (3D) radiative transfer models that act on the two-dimensional (2D) retrieved cross-section and a 3D atmosphere around it produced by a scene construction algorithm (SCA). This study proposes and tests a method for estimating errors in simulated TOA BB fluxes due to the SCA. Two methods for estimating SCA-related errors for TOA fluxes are presented. The primary one relies on computation of errors for reconstructed narrow-band imager nadir radiances. A-train satellite data were used to show that for constructed domains measuring (11 km)2, approximately the size of the EarthCARE assessment domains, with total cloud fractions > 0.2, errors for reflected BB short-wave fluxes due to the SCA are smaller than ±4.2 and ±11.5 W m-2 for 66 and 90% of the domains, respectively. Corresponding values for outgoing long-wave fluxes are ±1.2 and ±3.0 W m-2. The largest and smallest errors are associated with fields of broken convective cloud and overcast stratiform cloud, respectively. The SCA was applied to simulated measurements for a (153 km)2 field of deep convective clouds produced by a cloud-system-resolving model. Actual and estimated TOA BB short-wave flux errors due to the SCA agree well and are smaller than ±22 and ±40 W m-2 for 66 and 90% of the (11 km)2 sampled subdomains. Assuming that errors due to the SCA are purely bias errors, they were subtracted from fluxes estimated for the constructed domains. This resulted in TOA BB short-wave flux errors smaller than ±7 and ±25 W m-2 for 66 and 90% of the sampled subdomains. This suggests that estimated errors due to the SCA should be removed directly from simulated TOA BB fluxes before executing a closure assessment. © 2013 RoyalMeteorological Society."
"13606626700;55961887800;57212663824;14819302400;55961845900;7402820128;8943453100;","An integrated optical remote sensing system for environmental perturbation research",2013,"10.1109/JSTARS.2013.2250489","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84890124081&doi=10.1109%2fJSTARS.2013.2250489&partnerID=40&md5=600089efaa4c2f585ab13c3f1cf1680d","Remote sensing is the only technology that can systematically monitor physical properties of the biosphere over a vast region. However, it is still a challenge to make these measures meaningful for assessing the impacts of environmental perturbation. Here, we integrate an optical remote sensing system termed EcoiRS (Ecosystem observation by an integrated Remote Sensing system) specifically for this purpose. EcoiRS consists of three subsystems: an off-the-shelf atmospheric correction model (ACORN), a cloud/shadow removal model, and an advanced spectral mixture analysis model (AutoMCU). The core of ACORN is a set of radiative transfer codes that can be used to remove the effects of molecular/aerosol scatterings and water vapor absorption from remotely sensed data, and to convert these digital signals to surface reflectance. Shadow and cloud cover that would obscure the reflective properties of land surfaces in an image can be minimized by referring to their optical and thermal spectral profiles. AutoMCU executes iterative unmixing for each pixel using selected spectral endmembers based upon the rule of Monte Carlo simulation. The main outcomes of EcoiRS include cover fractions of green vegetation, non-photosynthetically active vegetation and bare soils, along with uncertainty measures for each pixel. The dynamics of these derived products are significant indicators for monitoring the change of states of terrestrial environments, and they can be used for investigating different environmental perturbations. Here, we demonstrate studies of implementing EcoiRS to map three major but relatively less studied cases in a western Pacific island (Taiwan): typhoons, tree diseases and alien plant invasion. © 2008-2012 IEEE."
"56263595100;57208346904;7401806579;25227357000;55371795600;","Cloud-Aerosol-Radiation (CAR) ensemble modeling system: Overall accuracy and efficiency",2013,"10.1007/s00376-012-2171-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874531904&doi=10.1007%2fs00376-012-2171-z&partnerID=40&md5=4baf653f98908b6fe08689cf4bd96634","The Cloud-Aerosol-Radiation (CAR) ensemble modeling system has recently been built to better understand cloud/aerosol/radiation processes and determine the uncertainties caused by different treatments of cloud/aerosol/radiation in climate models. The CAR system comprises a large scheme collection of cloud, aerosol, and radiation processes available in the literature, including those commonly used by the world's leading GCMs. In this study, detailed analyses of the overall accuracy and efficiency of the CAR system were performed. Despite the different observations used, the overall accuracies of the CAR ensemble means were found to be very good for both shortwave (SW) and longwave (LW) radiation calculations. Taking the percentage errors for July 2004 compared to ISCCP (International Satellite Cloud Climatology Project) data over (60°N, 60°S) as an example, even among the 448 CAR members selected here, those errors of the CAR ensemble means were only about -0.67% (-0.6 W m-2) and -0.82% (-2.0 W m-2) for SW and LW upward fluxes at the top of atmosphere, and 0.06% (0.1 W m-2) and -2.12% (-7.8 W m-2) for SW and LW downward fluxes at the surface, respectively. Furthermore, model SW frequency distributions in July 2004 covered the observational ranges entirely, with ensemble means located in the middle of the ranges. Moreover, it was found that the accuracy of radiative transfer calculations can be significantly enhanced by using certain combinations of cloud schemes for the cloud cover fraction, particle effective size, water path, and optical properties, along with better explicit treatments for unresolved cloud structures. © 2013 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"23012388900;57202119596;7004357137;","Reduction of radiation biases by incorporating the missing cloud variability by means of downscaling techniques: A study using the 3-D MoCaRT model",2012,"10.5194/amt-5-2261-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880536034&doi=10.5194%2famt-5-2261-2012&partnerID=40&md5=1750f377386a1875b021f018cacc9412","Handling complexity to the smallest detail in atmospheric radiative transfer models is unfeasible in practice. On the one hand, the properties of the interacting medium, i.e., the atmosphere and the surface, are only available at a limited spatial resolution. On the other hand, the computational cost of accurate radiation models accounting for three-dimensional heterogeneous media are prohibitive for some applications, especially for climate modelling and operational remote-sensing algorithms. Hence, it is still common practice to use simplified models for atmospheric radiation applications. Three-dimensional radiation models can deal with complex scenarios providing an accurate solution to the radiative transfer. In contrast, one-dimensional models are computationally more efficient, but introduce biases to the radiation results. With the help of stochastic models that consider the multi-fractal nature of clouds, it is possible to scale cloud properties given at a coarse spatial resolution down to a higher resolution. Performing the radiative transfer within the cloud fields at higher spatial resolution noticeably helps to improve the radiation results. We present a new Monte Carlo model, MoCaRT, that computes the radiative transfer in three-dimensional inhomogeneous atmospheres. The MoCaRT model is validated by comparison with the consensus results of the Intercomparison of Three-Dimensional Radiation Codes (I3RC) project. In the framework of this paper, we aim at characterising cloud heterogeneity effects on radiances and broadband fluxes, namely: the errors due to unresolved variability (the so-called plane parallel homogeneous, PPH, bias) and the errors due to the neglect of transversal photon displacements (independent pixel approximation, IPA, bias). First, we study the effect of the missing cloud variability on reflectivities. We will show that the generation of subscale variability by means of stochastic methods greatly reduce or nearly eliminate the reflectivity biases. Secondly, three-dimensional broadband fluxes in the presence of realistic inhomogeneous cloud fields sampled at high spatial resolutions are calculated and compared to their one-dimensional counterparts at coarser resolutions. We found that one-dimensional calculations at coarsely resolved cloudy atmospheres systematically overestimate broadband reflected and absorbed fluxes and underestimate transmitted ones. © 2012 Author(s)."
"12143654900;7005548544;","Comment on ""clouds and the Faint Young Sun Paradox"" by Goldblatt and Zahnle (2011)",2012,"10.5194/cp-8-701-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859367616&doi=10.5194%2fcp-8-701-2012&partnerID=40&md5=f25b25067751f7e463b620c6c9305d6f","Goldblatt and Zahnle (2011) raise a number of issues related to the possibility that cirrus clouds can provide a solution to the faint young sun paradox. Here, we argue that: (1) climates having a lower than present mean surface temperature cannot be discarded as solutions to the faint young sun paradox, (2) the detrainment from deep convective clouds in the tropics is a well-established physical mechanism for the formation of high clouds that have a positive radiative forcing (even if the possible role of these clouds as a negative climate feedback remains controversial) and (3) even if some cloud properties are not mutually consistent with observations in radiative transfer parameterizations, the most relevant consistency (for the purpose of hypothesis testing) is with observations of the cloud radiative forcing. Therefore, we maintain that cirrus clouds, as observed in the current climate and covering a large region of the tropics, can provide a solution to the faint young sun paradox, or at least ease the amount of CO 2 or other greenhouse substances needed to provide temperatures above freezing during the Archean. © 2012 Author(s)."
"55456627900;56878283500;6701620591;56230578500;23567595800;7006813055;6507472270;7003558701;35766719400;7006088102;7402883211;56051227300;","Comparison of surface UV irradiance in mountainous regions derived from satellite observations and model calculations with ground-based measurements",2010,"10.1127/0941-2948/2010/0347","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78649758794&doi=10.1127%2f0941-2948%2f2010%2f0347&partnerID=40&md5=323b76d63b0842a7a746969ec7a18bef","Several UV data products derived from satellite measurements, 1-D and 3-D radiative transfer modeling are compared with high-quality ground-based measurements. Data products include the UV index, erythemally weighted daily dose and spectrally resolved UV irradiances at 305, 310, 324 and 380 nm. The study focuses on the UV radiation climate in mountainous terrain under cloud-free conditions. The results show, that overall the 3-D- and the 1-D-model agree best with the measurements (average ratio 1.10 and 1.13, range 0.88-1.6). It is also found that snow and local topography have a rather minor impact on ground UV-irradiance, while altitude plays a significant role >5 %). Satellite-retrieved values significantly underestimate irradiance for most of our stations due to erroneous cloud correction (average ratio 0.89, range 0.6-1.35). However, if one compares the uncorrected (cloud-free) satellite-retrieved values to the measurements, the ratios are only slightly larger (average ratio 1.14, range 0.8 - 1.6) than for the 1-D- and 3-D-model. The main deficiencies arise in determining the correct surface height and albedo within the satellite-retrieval algorithm. © Gebrüder Borntraeger, Stuttgart 2010."
"8953038700;56537463000;","Cloud radiative effect on tropical troposphere to stratosphere transport represented in a large-scale model",2008,"10.1029/2008GL035673","https://www.scopus.com/inward/record.uri?eid=2-s2.0-58849098609&doi=10.1029%2f2008GL035673&partnerID=40&md5=bf8a94c63ec01ea763f5cf3f60151585","GFDL AM2 model simulations are analyzed to assess the simulated radiative effect of tropical tropopause layer (TTL) cirrus on tropical troposphere-to-stratosphere transport (TST). The strongest upward motion in the model's TTL is generally driven by dynamics instead of radiation, occurring in those TTL cloudy regions that overlap with optically thick clouds in the upper troposphere (UT). However, the occurrence frequency of such strong ascent is about one order of magnitude smaller than that of moderate ascent related to the radiative effect of TTL cirrus. The mean upward velocity of moderate ascent in the cloudy regions (∼-2.5 - -3.5 hPa/day) is one order of magnitude larger than that induced by TTL clear-sky radiative heating (∼-0.18 hPa/day). This supports the hypothesis that cirrus radiative heating contributes substantially to the average tropical TST rates. The implication for future model-satellite comparisons is discussed. Copyright 2008 by the American Geophysical Union."
"55688930000;7004242319;","Large-eddy simulations of the diurnal cycle of shallow convection and cloudiness over the tropical Indian Ocean",2008,"10.1002/qj.238","https://www.scopus.com/inward/record.uri?eid=2-s2.0-55349085803&doi=10.1002%2fqj.238&partnerID=40&md5=794bad37e6e5e10e8665f921e4bc4055","A 3-D non-hydrostatic model (EULAG) with warm-rain bulk microphysics was used to study the diurnal cycle of shallow convection and cloudiness in the trade wind boundary layer over the Indian Ocean. Simulations were initialized with soundings obtained during the Indian Ocean Experiment (INDOEX). In the absence of diurnally varying large-scale forcing, the simulated diurnal cycles of vertical velocities, turbulent fluxes, condensation rate and cloudiness were characterized by distinct daytime reductions. Solar heating in the boundary layer stabilized the air, decreased the relative humidity and, therefore, suppressed cloud-layer turbulence and shallow cumulus convection. As a result, the condensation rate and cloud amount were reduced. Stronger thermal updraughts and turbulent fluxes caused by solar heating in the mixed layer triggered the recovery of cloudiness in the afternoon when the instability in the cloud layer increased. Sensitivity experiments showed that the principal cause of the daytime heating of the atmosphere and reductions in convection and cloudiness was not the diurnally varying surface fluxes nor the cloud radiative effects, but rather the gaseous absorption of solar radiation due mainly to water vapour in the spectral band of 2500-14 500 cm-1 and ozone in the ultraviolet and visible bands. Compared to the average short-wave heating of 0.1 K day-1 due to cloud droplets, gases enhanced solar heating by about 2.0 K day-1 in the cloud layer. However, depending on its direction and magnitude, large-scale vertical motion can highly modulate the diurnal cycles driven by solar heating, representing a big uncertainty in observing the diurnal cycle of shallow cumuli. Copyright © 2008 Royal Meteorological Society."
"6506837510;7007108728;7005453346;7410070663;","The sensitivity of the radiation budget in a climate simulation to neglecting the effect of small ice particles",2007,"10.1175/JCLI4191.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547924537&doi=10.1175%2fJCLI4191.1&partnerID=40&md5=306fe46cfd97acf9152dbb0785cd4b13","The sensitivity of the atmospheric radiation budget to ignoring small ice particles (D ≤ 100 μm) in parameterization of the mean effective size of ice particles was investigated by using the Canadian Centre for Climate Modelling and Analysis (CCCma) third-generation general atmospheric circulation model (AGCM3). The results indicate that small ice particles play two crucial roles in the radiative transfer that influence the simulated climate. First, they inhibit the IR radiation from escaping to space and, second, they enhance the scattering of solar radiation. On average, these two effects tend to partially cancel each other out. However, based on AGCM simulations, the small ice crystals make clouds more opaque to IR radiation. Generally, 5-yr seasonally averaged GCM results suggest that the strongest anomalies in outgoing longwave radiation (OLR) are found in the Tropics, reaching 15 to 25 W m-2 in areas where cold high cirrus anvil clouds are prevalent. The global average change in net cloud radiative forcing was 2.4 W m-2 in June-August (JJA) and 1.7 W m-2 in December-February (DJF). The change in globally averaged 5-yr mean cloud forcing was close to 1.9 W m-2. When the small particles were included, the globally averaged 5-yr mean precipitation decreased by about 8%, but cloudiness increased only slightly (by 2%). The 5-yr averaged global mean surface (screen) temperature also increased slightly (about 0.2°C) when the small ice particles were included."
"15841350300;8670213100;55665366600;6507681572;7004639116;6603395511;6602137840;6701796418;","Spatial and temporal distribution of long-term short-wave surface radiation over Greece",2006,"10.1256/qj.05.163","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846892481&doi=10.1256%2fqj.05.163&partnerID=40&md5=003c3580cd6a154fc2bc93b18c59656f","The short-wave (SW) surface radiation budget (SRB, downward and absorbed fluxes) over Greece and surrounding areas has been computed for the first time, using a physical deterministic radiative-transfer model. The model computations were performed on a monthly-mean basis and at 2.5° × 2.5° latitude-longitude resolution over the 17-year period 1984-2000. Higher spatial resolution of 1° × 1° was achieved using the new NASA-Langley dataset but only for the shorter period 1985-1995. In the first case (2.5° × 2.5° resolution), the model input data were taken from global datasets, such as the International Satellite Cloud Climatology Project (ISCCP), the TIROS Operational Vertical Sounder (TOVS) or the Global Aerosol Dataset (GADS), as well as from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) and European Centre for Medium Range Weather Forecasts (ECMWF) Global Re-analysis Projects. In the second case (1° × 1° resolution), the model input data were taken from the NASA-Langley dataset supplemented by others (e.g., GADS). It is found that the annual mean values of the downward SW radiation at the surface (DSR) increase from about 150 W m-2 in the north of Greece to 210 W m-2 in the south. (Seasonal means are 50 and 100 W m-2, respectively, in the winter and 270 and 330 W m-2 in summer). The 1° × 1° DSR fluxes reveal significant geographical features, indicating an important longitudinal variation, with smaller values along the central mountain axis and in the northern part of the country. The annual mean DSR flux, averaged over the study area, is 181.9 ± 14.4 W m-2, calculated using the ISCCP-D2 (1984-2000) data or 188.8 ± 14.2 W m-2 using the NASA-Langley (1985-1995) data. The corresponding averaged mean surface absorbed fluxes are 164.7 ± 13.1 W m-2 and 170.7 ± 13.2 W m-2. Computed time series of annual mean solar radiation arriving at the surface, and a linear fit applied to them, show an increase with time which may possibly be related to climatic change. Time series of annual amplitude of DSR (maximum minus minimum monthly values) indicate a year-to-year variation of DSR of about 245 W m-2, whereas a linear fit shows an increase with time but no systematic increase in summer maxima or decrease in winter minima. The model-computed DSR fluxes are in good agreement with surface measurements, made at eight stations of the Hellenic National Meteorological Service and four other high-standard stations run by Greek research organizations, with correlation coefficients in the range 0.91-0.99 and standard deviations smaller than 20 W m-2. The ratio of direct to diffuse DSR (an indicator of clear skies) peaks during the summer months at a value of 1.5 in Thessaloniki (northern Greece), at about three in Athens and nine in Crete. © Royal Meteorological Society, 2006."
"35353151900;7202330299;36984879800;6506175295;7202444684;","Radiative properties of mid-latitude frontal ice-clouds observed by the shortwave and longwave radiometer-sondes",2004,"10.2151/jmsj.2004.639","https://www.scopus.com/inward/record.uri?eid=2-s2.0-3242784010&doi=10.2151%2fjmsj.2004.639&partnerID=40&md5=04569f9aa4f05c85a544b63e869bf435","In the Japanese Cloud and Climate Study (JACCS) cirrus experiment, simultaneous measurements of cloud radiative and microphysical properties were conducted by using the combined-sonde (radiometer-sonde + hydrometeor-video-sonde (HYVIS)) observation system at the Meteorological Research Institute (MRI), located at (36.05°N, 140.13°E) in Tsukuba, Japan, during early summer seasons from 1995 to 1999. We have analyzed the radiative properties of frontal ice-clouds observed by the shortwave and longwave radiometer-sondes (Asano et al. 2004). To interpret the observed radiative flux profiles, we have also performed radiative transfer calculations for horizontally homogeneous atmospheric models, where the single-scattering properties of ice-clouds were computed by anomalous diffraction theory for ice-crystals observed by HYVIS. On an average of the observed frontal ice-clouds, the shortwave reflectance, transmittance and absorptance were estimated to be 0.41 ± 0.03, 0.51 ± 0.06, and 0.08 ± 0.09, respectively, for the averaged ice-cloud layer with a mean visible optical thickness of 4.6 and a mean geometrical thickness of 5.4 km (mean volume extinction coefficient of 0.85 km-1). The ice-clouds were significantly heated by absorption of solar radiation in daytime. On the other hand, the mean effective emittance was estimated to be about 0.86 ± 0.37, showing that the frontal ice-clouds never acted as blackbody for longwave radiation. The lower parts of ice-cloud layers were heated by absorption of long-wave radiation from the surface and the atmosphere below the ice-clouds, while the upper parts were cooled by emission of longwave radiation to space. The shortwave and longwave heating profiles could make the daytime ice-cloud layers thermodynamically unstable. © 2004, Meteorological Society of Japan."
"6602080205;","Effect of cloud inhomogeneity on direct radiative forcing due to aerosols",2000,"10.1029/2000JD900223","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785563&doi=10.1029%2f2000JD900223&partnerID=40&md5=42ab01a4e3aff34e955706c1cbd016b6","The effect of including horizontal cloud inhomogeneity on the direct radiative forcing due to sulphate and soot aerosols is explored. Cloud inhomogeneity is represented using the gamma independent pixel approximation for optical depth. Using a two-stream radiation model, the assumption of plane-parallel clouds normally used in climate models is shown to systematically underestimate the magnitude of the negative radiative forcing due to sulphates and systematically overestimate the positive forcing due to soot aerosol. For overcast skies and a Northern Hemisphere mean aerosol profile, these biases can reach as much as 0.1 W m-2, representing up to 30% of the forcing for sulphates and 5% for soot. The bias introduced in forcing due to sulphate aerosol is much larger than would be expected from the effect of the different albedo produced by altering the treatment of cloud optical depth. For ""global mean"" conditions, considering both clear and cloudy regions, the biases are between 2 and 4% for all three quantities (around 0.04 W m-2 in radiative forcing). This bias can generally be reduced further by constraining the albedo to a fixed (observed) value, thereby using the plane parallel homogeneous approximation with a different (but incorrect) cloud optical depth. The sensitivity of these results to solar zenith angle, cloud properties, surface reflectance, the number of streams used in the radiative transfer model, and the relative humidity is also investigated. For regions with coincident overcast marine stratocumulus, high aerosol loading and high relative humidity, and an external mixture of soot and sulphate aerosol, absolute values of the bias in forcing due to sulphates could reach as much as 1.5 W m-2 for a solar zenith angle of 60°, this being around 15% of the total forcing. Copyright 2000 by the American Geophysical Union."
"7201844203;","Atmospheric solar heating in minor absorption bands",1999,"10.3319/TAO.1999.10.3.511(A)","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033460465&doi=10.3319%2fTAO.1999.10.3.511%28A%29&partnerID=40&md5=0f45c39868903c2510b3b505f6c83829","Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge amount of time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284 cm-1 to 25000 cm-1, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral-and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by ∼10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models."
"7201361035;","Inference of the climatic efficiency of clouds from satellite measurements",1995,"10.1080/01431169508954598","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029513129&doi=10.1080%2f01431169508954598&partnerID=40&md5=0e86c6720442a0792b60ee895dd197c8","The influence of clouds over the North Sea on the radiation field and on climate is investigated by analysing satellite measurements. The main interest is on high clouds due to their ambivalent behaviour in the radiation field. To quantify the influence of clouds on climate, the cloud-climate efficiency is introduced. The cloud-climate efficiency allows us to estimate the gain or respectively loss of energy of the earth/atmosphere system in the presence of a cloud, which can be specified by a cloud classification. The spatial integration of the cloud-climate efficiencies results in the cloud forcing defined by the difference of the radiative fluxes within a clear sky and a cloudy satellite image pixel. The first step is an accurate detailed cloud classification based on the maximum likelihood method. The method developed for National Oceanograph and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA AVHRR) data and Meteosat data can be used to discriminate 24 clouds, especially high clouds with different optical depths. Evaluating these results, a good agreement between the cloud types inferred from satellite data and from synoptical observations could be achieved. In the following step transmittances of high clouds could be determined by using NOAA AVHRR data, where for the solar spectrum a simple radiative transfer scheme is applied. For the longwave spectrum, an equation after Platt is used. Comparing these transmittances with groand based observations during field experiments (ICE’87, ICE’89. IGPB’90), good agreements could be foand. Using NOAA AVHRR data, the derived information is applied to compute the cloud-climate efficiency at the top of the atmosphere. It can be seen that in the shortwave spectrum the cloud-climate efficiency shows a general cooling effect of the earth/atmosphere system for all clouds and a strong dependence on the insolation. Regarding the cloud-climate efficiency in the longwave spectrum, a heating of the earth/atmosphere system due to clouds was always observed. Thus, high clouds with the same optical properties may lead to different effects in the earth/atmosphere system depending on the anderlying surface, on the optical depths of that cloud, and on the geographical appearance related to the insolation. An approach to compare the increasing cloud forcing at the top of the atmosphere with an analysis of the relative topography 300/850 hPa shows that the increase of the cloud forcing is well correlated with an increase of the temperature in this layer. © 1995 Taylor & Francis Group, LLC."
"56597778200;47361484200;57193948689;55749785900;57213606659;57213598451;6701410329;15840467900;35069282600;35799889800;","Cloud_cci Advanced Very High Resolution Radiometer post meridiem (AVHRR-PM) dataset version 3: 35-year climatology of global cloud and radiation properties",2020,"10.5194/essd-12-41-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077846870&doi=10.5194%2fessd-12-41-2020&partnerID=40&md5=f54a974b5a7331025cf3f63e827dc208","We present version 3 of the Cloud_cci Advanced Very High Resolution Radiometer post meridiem (AVHRR-PM) dataset, which contains a comprehensive set of cloud and radiative flux properties on a global scale covering the period of 1982 to 2016. The properties were retrieved from AVHRR measurements recorded by the afternoon (post meridiem - PM) satellites of the National Oceanic and Atmospheric Administration (NOAA) Polar Operational Environmental Satellite (POES) missions. The cloud properties in version 3 are of improved quality compared with the precursor dataset version 2, providing better global quality scores for cloud detection, cloud phase and ice water path based on validation results against A-Train sensors. Furthermore, the parameter set was extended by a suite of broadband radiative flux properties. They were calculated by combining the retrieved cloud properties with thermodynamic profiles from reanalysis and surface properties. The flux properties comprise upwelling and downwelling and shortwave and longwave broadband fluxes at the surface (bottom of atmosphere - BOA) and top of atmosphere (TOA). All fluxes were determined at the AVHRR pixel level for all-sky and clear-sky conditions, which will particularly facilitate the assessment of the cloud radiative effect at the BOA and TOA in future studies. Validation of the BOA downwelling fluxes against the Baseline Surface Radiation Network (BSRN) shows a very good agreement. This is supported by comparisons of multi-annual mean maps with NASA's Clouds and the Earth's Radiant Energy System (CERES) products for all fluxes at the BOA and TOA. The Cloud_cci AVHRR-PM version 3 (Cloud_cci AVHRR-PMv3) dataset allows for a large variety of climate applications that build on cloud properties, radiative flux properties and/or the link between them. © 2020. This work is distributed under the Creative Commons Attribution 4.0 License For the presented Cloud_cci AVHRR-PMv3 dataset a digital object identifier has been issued: https://doi.org/10.5676/DWD/ESA_Cloud_cci/AVHRR-PM/V003 (Stengel et al., 2019). © 2020. This work is distributed under the Creative Commons Attribution 4.0 License."
"7004364155;7102651635;56493740900;55942502100;8891521600;13204619900;6603546080;24322892500;25031430500;","Toward a consistent definition between satellite and model clear-sky radiative fluxes",2020,"10.1175/JCLI-D-19-0381.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081540622&doi=10.1175%2fJCLI-D-19-0381.1&partnerID=40&md5=cd1c1800175f591b54e755d800c710cb","A new method of determining clear-sky radiative fluxes from satellite observations for climate model evaluation is presented. The method consists of applying adjustment factors to existing satellite clear-sky broadband radiative fluxes that make the observed and simulated clear-sky flux definitions more consistent. The adjustment factors are determined from the difference between observation-based radiative transfer model calculations of monthly mean clear-sky fluxes obtained by ignoring clouds in the atmospheric column and by weighting hourly mean clear-sky fluxes with imager-based clear-area fractions. The global mean longwave (LW) adjustment factor is -2.2 W m-2 at the top of the atmosphere and 2.7 W m-2 at the surface. The LW adjustment factors are pronounced at high latitudes during winter and in regions with high uppertropospheric humidity and cirrus cloud cover, such as over the west tropical Pacific, and the South Pacific and intertropical convergence zones. In the shortwave (SW), global mean adjustment is 0.5 W m-2 at TOA and -1.9 W m-2 at the surface. It is most pronounced over sea ice off of Antarctica and over heavy aerosol regions, such as eastern China. However, interannual variations in the regional SW and LW adjustment factors are small compared to those in cloud radiative effect. After applying the LW adjustment factors, differences in zonal mean cloud radiative effect between observations and climate models decrease markedly between 60°S and 60°N and poleward of 65°N. The largest regional improvements occur over the west tropical Pacific and Indian Oceans. In contrast, the impact of the SW adjustment factors is much smaller. © 2019 American Meteorological Society."
"55688930000;7006270084;36657850900;15755995900;55544607500;56384704800;57214786060;7006705919;22953153500;7003666669;55317190600;55802246600;55720018700;7404544551;8570871900;7202048112;55717074000;13007924700;56049520900;25629055800;7401936984;55317177900;","Aerosols in the E3SM Version 1: New Developments and Their Impacts on Radiative Forcing",2020,"10.1029/2019MS001851","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078849803&doi=10.1029%2f2019MS001851&partnerID=40&md5=85b34f6275e02272599ab79af8c3cb28","The new Energy Exascale Earth System Model Version 1 (E3SMv1) developed for the U.S. Department of Energy has significant new treatments of aerosols and light-absorbing snow impurities as well as their interactions with clouds and radiation. This study describes seven sets of new aerosol-related treatments (involving emissions, new particle formation, aerosol transport, wet scavenging and resuspension, and snow radiative transfer) and examines how they affect global aerosols and radiative forcing in E3SMv1. Altogether, they give a reduced total aerosol radiative forcing (−1.6 W/m2) and sensitivity in cloud liquid water to aerosols, but an increased sensitivity in cloud droplet size to aerosols. A new approach for H2SO4 production and loss largely reduces a low bias in small particles concentrations and leads to substantial increases in cloud condensation nuclei concentrations and cloud radiative cooling. Emitting secondary organic aerosol precursor gases from elevated sources increases the column burden of secondary organic aerosol, contributing substantially to global clear-sky aerosol radiative cooling (−0.15 out of −0.5 W/m2). A new treatment of aerosol resuspension from evaporating precipitation, developed to remedy two shortcomings of the original treatment, produces a modest reduction in aerosols and cloud droplets; its impact depends strongly on the model physics and is much stronger in E3SM Version 0. New treatments of the mixing state and optical properties of snow impurities and snow grains introduce a positive present-day shortwave radiative forcing (0.26 W/m2), but changes in aerosol transport and wet removal processes also affect the concentration and radiative forcing of light-absorbing impurities in snow/ice. © 2019. The Authors."
"25928285500;57208134302;8909993500;35734944400;","Radiative effect of clouds at ny-Ålesund, svalbard, as inferred from ground-based remote sensing observations",2020,"10.1175/JAMC-D-19-0080.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078262322&doi=10.1175%2fJAMC-D-19-0080.1&partnerID=40&md5=b9363e0e52e4a61c8fe8be27e7d61c1e","For the first time, the cloud radiative effect (CRE) has been characterized for the Arctic site Ny-Ålesund, Svalbard, Norway, including more than 2 years of data (June 2016–September 2018). The cloud radiative effect, that is, the difference between the all-sky and equivalent clear-sky net radiative fluxes, has been derived based on a combination of ground-based remote sensing observations of cloud properties and the application of broadband radiative transfer simulations. The simulated fluxes have been evaluated in terms of a radiative closure study. Good agreement with observed surface net shortwave (SW) and longwave (LW) fluxes has been found, with small biases for clear-sky (SW: 3.8 W m_2; LW: -4.9 W m_2) and all-sky (SW: -5.4 W m_2;LW: -0.2 W m_2) situations. For monthly averages, uncertainties in the CRE are estimated to be small (~2Wm_2). At Ny-Ålesund, the monthly net surface CRE is positive from September to April/May and negative in summer. The annual surface warming effect by clouds is 11.1 W m_2.The longwave surface CRE of liquid-containing cloud is mainly driven by liquid water path (LWP) with an asymptote value of 75 W m_2 for large LWP values. The shortwave surface CRE can largely be explained by LWP, solar zenith angle, and surface albedo. Liquid-containing clouds (LWP > 5gm_2) clearly contribute most to the shortwave surface CRE (70%–98%) and, from late spring to autumn, also to the longwave surface CRE (up to 95%). Only in winter are ice clouds (IWP > 0gm_2;LWP< 5gm_2) equally important or even dominating the signal in the longwave surface CRE. © 2019 American Meteorological Society."
"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."
"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."
"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."
"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."
"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"
"56533209900;56234308500;35364938500;7403596593;55234835700;57201614282;6506539438;56499447000;","Multitimescale variations in modeled stratospheric water vapor derived from three modern reanalysis products",2019,"10.5194/acp-19-6509-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065826822&doi=10.5194%2facp-19-6509-2019&partnerID=40&md5=17e8814873950c188e668d0c6756f6b7","Stratospheric water vapor (SWV) plays important roles in the radiation budget and ozone chemistry and is a valuable tracer for understanding stratospheric transport. Meteorological reanalyses provide variables necessary for simulating this transport; however, even recent reanalyses are subject to substantial uncertainties, especially in the stratosphere. It is therefore necessary to evaluate the consistency among SWV distributions simulated using different input reanalysis products. In this study, we evaluate the representation of SWV and its variations on multiple timescales using simulations over the period 1980-2013. Our simulations are based on the Chemical Lagrangian Model of the Stratosphere (CLaMS) driven by horizontal winds and diabatic heating rates from three recent reanalyses: ERA-Interim, JRA-55 and MERRA-2. We present an intercomparison among these model results and observationally based estimates using a multiple linear regression method to study the annual cycle (AC), the quasi-biennial oscillation (QBO), and longer-term variability in monthly zonal-mean H2O mixing ratios forced by variations in the El Niño-Southern Oscillation (ENSO) and the volcanic aerosol burden. We find reasonable consistency among simulations of the distribution and variability in SWV with respect to the AC and QBO. However, the amplitudes of both signals are systematically weaker in the lower and middle stratosphere when CLaMS is driven by MERRA-2 than when it is driven by ERA-Interim or JRA-55. This difference is primarily attributable to relatively slow tropical upwelling in the lower stratosphere in simulations based on MERRA-2. Two possible contributors to the slow tropical upwelling in the lower stratosphere are suggested to be the large long-wave cloud radiative effect and the unique assimilation process in MERRA-2. The impacts of ENSO and volcanic aerosol on H2O entry variability are qualitatively consistent among the three simulations despite differences of 50 %-100 % in the magnitudes. Trends show larger discrepancies among the three simulations. CLaMS driven by ERA-Interim produces a neutral to slightly positive trend in H2O entry values over 1980-2013 (+0.01 ppmv decade-1), while both CLaMS driven by JRA-55 and CLaMS driven by MERRA-2 produce negative trends but with significantly different magnitudes (-0.22 and -0.08 ppmv decade-1, respectively). © Author(s) 2019."
"57208745275;6701606453;","Quantifying variations in shortwave aerosol-cloud-radiation interactions using local meteorology and cloud state constraints",2019,"10.5194/acp-19-6251-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065659528&doi=10.5194%2facp-19-6251-2019&partnerID=40&md5=26a865fbd56e1c5d13a00b99d8f96d0c","While many studies have tried to quantify the sign and the magnitude of the warm marine cloud response to aerosol loading, both remain uncertain, owing to the multitude of factors that modulate microphysical and thermodynamic processes within the cloud. Constraining aerosol� cloud interactions using the local meteorology and cloud liquid water may offer a way to account for covarying influences, potentially increasing our confidence in observational estimates of warm cloud indirect effects. A total of 4 years of collocated satellite observations from the NASA A-Train constellation, combined with reanalysis from MERRA-2, are used to partition marine warm clouds into regimes based on stability, the free atmospheric relative humidity, and liquid water path. Organizing the sizable number of satellite observations into regimes is shown to minimize the covariance between the environment or liquid water path and the indirect effect. Controlling for local meteorology and cloud state mitigates artificial signals and reveals substantial variance in both the sign and magnitude of the cloud radiative response, including regions where clouds become systematically darker with increased aerosol concentration in dry, unstable environments. A darkening effect is evident even under the most stringent of constraints. These results suggest it is not meaningful to report a single global sensitivity of cloud radiative effect to aerosol. To the contrary, we find the sensitivity can range from 0:46 to 0.11Wm2 ln(AI)1 regionally. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License."
"55462884000;6701562113;56612517400;57194470383;16246205000;57207176515;","The Weather Research and Forecasting Model with Aerosol-Cloud Interactions (WRF-ACI): Development, evaluation, and initial application",2019,"10.1175/MWR-D-18-0267.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065845185&doi=10.1175%2fMWR-D-18-0267.1&partnerID=40&md5=29d15080cbf4a868241d84483226f0a9","The Weather Research and Forecasting Model with Aerosol-Cloud Interactions (WRF-ACI) is developed for studying aerosol effects on gridscale and subgrid-scale clouds using common aerosol activation and ice nucleation formulations and double-moment cloud microphysics in a scale-aware subgrid-scale parameterization scheme. Comparisons of both the standard WRF and WRF-ACI models' results for a summer season against satellite and reanalysis estimates show that the WRF-ACI system improves the simulation of cloud liquid and ice water paths. Correlation coefficients for nearly all evaluated parameters are improved, while other variables show slight degradation. Results indicate a strong cloud lifetime effect from current climatological aerosols increasing domain average cloud liquid water path and reducing domain average precipitation as compared to a simulation with aerosols reduced by 90%. Increased cloud-top heights indicate a thermodynamic invigoration effect, but the impact of thermodynamic invigoration on precipitation is overwhelmed by the cloud lifetime effect. A combination of cloud lifetime and cloud albedo effects increases domain average shortwave cloud forcing by ~3.0 W m-2. Subgrid-scale clouds experience a stronger response to aerosol levels, while gridscale clouds are subject to thermodynamic feedbacks because of the design of the WRF modeling framework. The magnitude of aerosol indirect effects is shown to be sensitive to the choice of autoconversion parameterization used in both the gridscale and subgrid-scale cloud microphysics, but spatial patterns remain qualitatively similar. These results indicate that the WRF-ACI model provides the community with a computationally efficient tool for exploring aerosol-cloud interactions. © 2019 American Meteorological Society."
"8658386900;57192820631;35478813200;57198616562;6506537159;20433705700;24722339600;","Midlatitude Oceanic Cloud and Precipitation Properties as Sampled by the ARM Eastern North Atlantic Observatory",2019,"10.1029/2018JD029667","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065024351&doi=10.1029%2f2018JD029667&partnerID=40&md5=2a4a248cc9a6ca87f145da7f8b788b3f","Marine low clouds are critical to the climate system because of their extensive coverage and associated controls on boundary layer dynamics and radiative energy balance. The primary foci for this study are marine low cloud observations over a heavily instrumented site on the Azores archipelago in the Eastern North Atlantic and their associated raindrop size distribution (DSD) properties, relative low cloud contributions to the precipitation, and additional sampling (instrument, environmental) considerations. The contribution from low clouds (e.g., cloud top < 4 km) to the overall precipitation over midlatitude oceans is poorly understood, in part because of the lack of coupled, high-quality measurements of precipitation and low cloud properties. Cloud regime and precipitation breakdowns performed for a multiyear (2014–2017) record emphasize diurnal precipitation and raindrop size distribution characteristics for both low and deeper clouds, as well as differences between the two disdrometer types used. Results demonstrate that marine low clouds over this Eastern North Atlantic location account for a significant (45%) contribution to the total rainfall and exhibit a diurnal cycle in cloud (thickness, top, and base) and precipitation characteristics similar to satellite records. Additional controls on observed surface rainfall characteristics of low clouds allowed by the extended ground-based facility data sets are also explored. From those analyses, it is suggested that the synoptic state exerts a significant control on low cloud and surface precipitation properties. ©2019. American Geophysical Union. All Rights Reserved."
"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)."
"57194833104;56482796700;56571063800;24402359000;7004469744;7003591311;","An emulator approach to stratocumulus susceptibility",2019,"10.5194/acp-19-10191-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070613374&doi=10.5194%2facp-19-10191-2019&partnerID=40&md5=b7c5839e25c4562e4ac633cd164b4e4c","The climatic relevance of aerosol-cloud interactions depends on the sensitivity of the radiative effect of clouds to cloud droplet number N, and liquid water path LWP. We derive the dependence of cloud fraction CF, cloud albedo AC, and the relative cloud radiative effect rCRE D CF • AC on N and LWP from 159 large-eddy simulations of nocturnal stratocumulus. These simulations vary in their initial conditions for temperature, moisture, boundary-layer height, and aerosol concentration but share boundary conditions for surface fluxes and subsidence. Our approach is based on Gaussian-process emulation, a statistical technique related to machine learning. We succeed in building emulators that accurately predict simulated values of CF, AC, and rCRE for given values of N and LWP. Emulator-derived susceptibilities @ lnrCRE=@ lnN and @ lnrCRE=@ lnLWP cover the nondrizzling, fully overcast regime as well as the drizzling regime with broken cloud cover. Theoretical results, which are limited to the nondrizzling regime, are reproduced. The susceptibility @ lnrCRE=@ lnN captures the strong sensitivity of the cloud radiative effect to cloud fraction, while the susceptibility @ lnrCRE=@ lnLWP describes the influence of cloud amount on cloud albedo irrespective of cloud fraction. Our emulation-based approach provides a powerful tool for summarizing complex data in a simple framework that captures the sensitivities of cloud-field properties over a wide range of states. © 2019 Author(s)."
"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."
"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."
"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."
"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"
"56342763100;7101755461;","Tropopause evolution in a rapidly intensifying tropical cyclone: A static stability budget analysis in an idealized axisymmetric framework",2019,"10.1175/JAS-D-18-0097.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060019399&doi=10.1175%2fJAS-D-18-0097.1&partnerID=40&md5=f59f130c458e9f3579007738ff9ea8a9","Upper-level static stability (N 2 ) variations can influence the evolution of the transverse circulation and potential vorticity in intensifying tropical cyclones (TCs). This paper examines these variations during the rapid intensification (RI) of a simulated TC.Over the eye,N 2 near the tropopause decreases and the cold-point tropopause rises by up to 4 kmat the storm center. Outside of the eye,N 2 increases considerably just above the cold-point tropopause and the tropopause remains near its initial level.Abudget analysis reveals that the advection terms, which include differential advection of potential temperature θ and direct advection of N 2 , are important throughout the upper troposphere and lower stratosphere.These terms are particularly pronounced within the eye,where they destabilize the layer near and above the cold-point tropopause. Outside of the eye, a radial-vertical circulation develops duringRI, with strong outflow below the tropopause and weak inflow above. Differential advection of θ near the outflow jet provides forcing for stabilization below the outflow maximumand destabilization above. Turbulence induced by vertical wind shear on the flanks of the outflow maximum also modifies the vertical stability profile. Meanwhile, radiative cooling tendencies at the top of the cirrus canopy generally act to destabilize the upper troposphere and stabilize the lower stratosphere. The results suggest that turbulence and radiation, alongside differential advection, play fundamental roles in the upper-level N 2 evolution of TCs. These N 2 tendencies could have implications for both the TC diurnal cycle and the tropopause-layer potential vorticity evolution in TCs. © 2019 American Meteorological Society."
"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."
"55480310900;8293804700;24385863600;","Cloud droplet activation of organic-salt mixtures predicted from two model treatments of the droplet surface",2018,"10.1039/c8em00345a","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056503868&doi=10.1039%2fc8em00345a&partnerID=40&md5=1ba8b5ccc712ebfb6b1c16feba520113","The droplet surface plays important roles in the interaction between organic aerosols with clouds and climate. Surface active organic compounds can partition to the droplet surface, depleting the solute from the droplet bulk or depressing the droplet surface tension. This may in turn affect the shape of the droplet growth curve, threshold of aerosol activation into cloud droplets, activated droplet size distributions, and cloud radiative effects. In this work, a new monolayer model along with a traditional Gibbs adsorption isotherm model was used in conjunction with equilibrium Köhler theory to predict cloud condensation nuclei (CCN) activation of both simple and complex surface active model aerosol systems. For the surface active aerosol considered, the monolayer droplet model produces similar results to the Gibbs model as well as comparable results to CCN measurements from the literature, even for systems where specific molecular identities and aqueous properties are unknown. The monolayer model is self-contained and fully prognostic, and provides a versatile, conceptually simple, yet physically based model for understanding the role of organic surfactants in cloud droplet formation. © The Royal Society of Chemistry."
"56250119900;55796882100;","A Comparison of Cloud Classification Methodologies: Differences Between Cloud and Dynamical Regimes",2018,"10.1029/2018JD028595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054692208&doi=10.1029%2f2018JD028595&partnerID=40&md5=58569ac832d7119ef6c9ee1fef143246","Classifications of cloud data into Cloud Regimes (CRs) and compositing based on meteorological parameters, Dynamic Regimes (DRs), are often used in the analysis of clouds. We compare CR and DR classifications to understand the relative merits of these approaches and develop a comparison methodology for future studies. We apply the Self-Organizing Map technique to International Satellite Cloud Climatology Project (ISCCP) D1 joint histograms to produce a CR and ERA-Interim pressure vertical velocity output to produce a DR. The CR created improves the separation between high-level CRs compared to previous work. Composites of ISCCP joint histogram data using the DR produce coherent groupings similar to those in the CR scheme particularly in regions of ascent. Both classifications display coherent geographical patterns and reproduce relationships between vertical velocity and cloud properties. However, the CR produces more coherent clusters with higher intracluster similarity and a greater range of independent cloud classes. Independent tests of composites using ISCCP FD output show that the regional variability of longwave cloud radiative effect for particular nodes are significantly higher in the DR than the CR scheme suggesting a poorer classification. Composite mean CloudSat reflectivity-altitude joint histograms represent all major cloud types in the CR scheme, while the current DR grouping is less coherent and misses classes. This suggests that the CR scheme is a more useful classification than the DR scheme based solely on vertical velocity data. Contingency table analysis indicates a low association between these classifications, suggesting combining these schemes would be valuable. ©2018. American Geophysical Union. All Rights Reserved."
"55087038900;56274362400;37025898200;","The impact of cloud radiative effects on the tropical tropopause layer temperatures",2018,"10.3390/atmos9100377","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054362933&doi=10.3390%2fatmos9100377&partnerID=40&md5=a8aeeb51aa56e3c99ae28f2fcdff5300","A single-column radiative-convective model (RCM) is a useful tool to investigate the physical processes that determine the tropical tropopause layer (TTL) temperature structures. Previous studies on the TTL using the RCMs, however, omitted the cloud radiative effects. In this study, we examine the impact of cloud radiative effects on the simulated TTL temperatures using an RCM.We derive the cloud radiative effects based on satellite observations, which show heating rates in the troposphere but cooling rates in the stratosphere. We find that the cloud radiative effect warms the TTL by as much as 2 K but cools the lower stratosphere by as much as -1.5 K, resulting in a thicker TTL.With (without) considering cloud radiative effects, we obtain a convection top of ≈167 hPa (≈150 hPa) with a temperature of ≈213 K (≈209 K), and a cold point at ≈87 hPa (≈94 hPa) with a temperature of ≈204 K (≈204 K). Therefore, the cloud radiative effects widen the TTL by both lowering the convection-top height and enhancing the cold-point height. We also examine the impact of TTL cirrus radiative effects on the RCM-simulated temperatures. We find that the TTL cirrus warms the TTL with a maximum temperature increase of ≈1.3 K near 110 hPa. © 2018 by the authors."
"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."
"57195576398;25941200000;35572096100;9239331500;24337947000;56009810800;35317714900;7003557662;6602681732;6602922400;12800966700;7003535385;8397494800;35567153700;6603631763;","Evaluation of a high-resolution numerical weather prediction model's simulated clouds using observations from CloudSat, GOES-13 and in situ aircraft",2018,"10.1002/qj.3318","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054533459&doi=10.1002%2fqj.3318&partnerID=40&md5=a777a4a748952ef2711a1970af7f1d10","This study aimed to assess tropical cloud properties predicted by Environment and Climate Change Canada's Global Environmental Multiscale (GEM) model when run with the Milbrandt–Yau double-moment cloud microphysical scheme and one-way nesting that culminated at a (∼300 km)2 inner domain with 0.25 km horizontal grid spacing. The assessment utilized satellite and in situ data collected during the High Ice Water Content (HIWC) and High Altitude Ice Crystals (HAIC) projects for a mesoscale convective system on 16 May 2015 over French Guiana. Data from CloudSat's cloud-profiling radar and GOES-13's imager were compared to data either simulated directly by GEM or produced by operating on GEM's cloud data with both the CFMIP (Cloud Feedback Model Intercomparison Project) Observation Simulator Package (COSP) instrument simulator and a three-dimensional Monte Carlo solar radiative transfer model. In situ observations were made from research aircraft – Canada's National Research Council Convair-580 and the French SAFIRE Falcon-20 – whose flight paths were aligned with CloudSat's ground-track. Spatial and temporal shifts of clouds simulated by GEM compared well to GOES-13 imagery. There are, however, differences between simulated and observed amounts of high and low cloud. While GEM did well at predicting ranges of ice-water content (IWC) near 11 km altitude (Falcon-20), it produces too much graupel and snow near 7 km (Convair-580). This produced large differences between CloudSat's and COSP-generated radar reflectivities and two-way attenuations. On the other hand, CloudSat's inferred values of IWC agree well with in situ samples at both altitudes. Generally, GEM's visible reflectances exceeded GOES-13's on account of having produced too much low-level liquid cloud. It is expected that GEM's disproportioning of cloud hydrometeors will improve once it includes a better representation of secondary ice production. © 2018 Her Majesty the Queen in Right of Canada. Quarterly Journal of the Royal Meteorological Society © 2018 Royal Meteorological Society"
"7006614696;35509639400;","Radiative invigoration of tropical convection by preceding cirrus clouds",2018,"10.1175/JAS-D-17-0355.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047084864&doi=10.1175%2fJAS-D-17-0355.1&partnerID=40&md5=3ffa6030248a17f0e3ca0c5a2fec2f46","This work seeks evidence for convective-radiative interactions in satellite measurements, with a focus on the variability over the life cycle of tropical convection in search of the underlying processes at a fundamental level of the convective dynamics. To this end, the vertical profiles of cloud cover and radiative heating from the CloudSat-CALIPSO products are sorted into a composite time series around the hour of convective occurrence identified by the TRMM PR. The findings are summarized as follows. Cirrus cloud cover begins to increase, accompanied by a notable reduction of longwave cooling, in moist atmospheres even 1-2 days before deep convection is invigorated. In contrast, longwave cooling stays efficient and clouds remain shallow where the ambient air is very dry. To separate the radiative effects by the preceding cirrus clouds on convection from the direct effects of moisture, the observations with enhanced cirrus cover are isolated from those with suppressed cirrus under a moisture environment being nearly equal. It is found that rain rate is distinctly higher if the upper troposphere is cloudier regardless of moisture, suggesting that the cirrus radiative effects may be linked with the subsequent growth of convection. A possible mechanism to support this observational implication is discussed using a simple conceptual model. The model suggests that the preceding cirrus clouds could radiatively promote the moistening with the aid of the congestus-mode dynamics within a short period of time (about 2 days) as observed. © 2018 American Meteorological Society."
"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."
"57190862866;56032970700;22934904700;7401945370;57212988186;","Impact of Precipitating Ice Hydrometeors on Longwave Radiative Effect Estimated by a Global Cloud-System Resolving Model",2018,"10.1002/2017MS001180","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041306785&doi=10.1002%2f2017MS001180&partnerID=40&md5=1941ac671067f49dc05c3718a6c65ca3","Satellite observation and general circulation model (GCM) studies suggest that precipitating ice makes nonnegligible contributions to the radiation balance of the Earth. However, in most GCMs, precipitating ice is diagnosed and its radiative effects are not taken into account. Here we examine the longwave radiative impact of precipitating ice using a global nonhydrostatic atmospheric model with a double-moment cloud microphysics scheme. An off-line radiation model is employed to determine cloud radiative effects according to the amount and altitude of each type of ice hydrometeor. Results show that the snow radiative effect reaches 2 W m−2 in the tropics, which is about half the value estimated by previous studies. This effect is strongly dependent on the vertical separation of ice categories and is partially generated by differences in terminal velocities, which are not represented in GCMs with diagnostic precipitating ice. Results from sensitivity experiments that artificially change the categories and altitudes of precipitating ice show that the simulated longwave heating profile and longwave radiation field are sensitive to the treatment of precipitating ice in models. This study emphasizes the importance of incorporating appropriate treatments for the radiative effects of precipitating ice in cloud and radiation schemes in GCMs in order to capture the cloud radiative effects of upper level clouds. © 2018. The Authors."
"7006306835;7005808242;","Modeling water vapor and clouds as passive tracers in an idealized GCM",2018,"10.1175/JCLI-D-16-0812.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040582845&doi=10.1175%2fJCLI-D-16-0812.1&partnerID=40&md5=7b31e96f55492e0ab82f9fa12b9fdd39","This paper introduces an idealized general circulation model (GCM) in which water vapor and clouds are tracked as tracers, but are not allowed to affect circulation through either latent heat release or cloud radiative effects. The cloud scheme includes an explicit treatment of cloud microphysics and diagnoses cloud fraction from a prescribed subgrid distribution of total water. The model is capable of qualitatively capturing many large-scale features of water vapor and cloud distributions outside of the boundary layer and deep tropics. The subtropical dry zones, midlatitude storm tracks, and upper-tropospheric cirrus are simulated reasonably well. The inclusion of cloud microphysics (namely rain re-evaporation) has a modest but significant effect of moistening the lower troposphere in this model. When being subjected to a uniform fractional increase of saturated water vapor pressure, the model produces little change in cloud fraction. A more realistic perturbation, which considers the nonlinearity of the Clausius-Clapeyron relation and spatial structure of CO2-induced warming, results in a substantial reduction in the free-tropospheric cloud fraction. This is reconciled with an increase of relative humidity by analyzing the probability distributions of both quantities, and may help explain partly similar decreases in cloud fraction in full GCMs. The model provides a means to isolate individual processes or model components for studying their influences on cloud simulation in the extratropical free troposphere. © 2018 American Meteorological Society."
"7103386012;7003279098;56465386500;56026569200;57195218855;57191077410;","Dimethylsulfide model calibration and parametric sensitivity analysis for the Greenland Sea",2017,"10.1016/j.polar.2017.07.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026329819&doi=10.1016%2fj.polar.2017.07.001&partnerID=40&md5=bfecef7bb3656272f649f513bb8e3253","Sea-to-air fluxes of marine biogenic aerosols have the potential to modify cloud microphysics and regional radiative budgets, and thus moderate Earth's warming. Polar regions play a critical role in the evolution of global climate. In this work, we use a well-established biogeochemical model to simulate the DMS flux from the Greenland Sea (20°W–10°E and 70°N–80°N) for the period 2003–2004. Parameter sensitivity analysis is employed to identify the most sensitive parameters in the model. A genetic algorithm (GA) technique is used for DMS model parameter calibration. Data from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are used to drive the DMS model under 4 × CO2 conditions. DMS flux under quadrupled CO2 levels increases more than 300% compared with late 20th century levels (1 × CO2). Reasons for the increase in DMS flux include changes in the ocean state—namely an increase in sea surface temperature (SST) and loss of sea ice—and an increase in DMS transfer velocity, especially in spring and summer. Such a large increase in DMS flux could slow the rate of warming in the Arctic via radiative budget changes associated with DMS-derived aerosols. © 2017 Elsevier B.V. and NIPR"
"57213967598;36606783400;24329947300;7004351010;8548304600;8836278700;","Satellite-retrieved direct radiative forcing of aerosols over North-East India and adjoining areas: climatology and impact assessment",2017,"10.1002/joc.5004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013249507&doi=10.1002%2fjoc.5004&partnerID=40&md5=22cdb3a939c330ec4d505bca3483662a","In order to understand the climatic implications of atmospheric aerosols, top of atmosphere (TOA) shortwave (SW, 0.3–5 µm) fluxes and aerosol optical depth (AOD) at 550 nm retrieved simultaneously by clouds and the earth's radiant energy system (CERES) and moderate resolution imaging spectroradiometer (MODIS) instruments, respectively, are analysed over North-East India and its adjoining areas for the period July 2002–December 2013. The aerosol-free TOA flux obtained by establishing the linear regression between CERES SW TOA fluxes and MODIS AODs exhibits strong seasonality with peak values in monsoon and minimum in winter. Same seasonality is captured by the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model, but with difference in absolute values. SBDART code is used to extend instantaneous radiative forcing estimates into 24-h averages. AOD over the North East India region with complex terrain shows altitudinal variation with maximum value at the lowest elevation site Dhaka and minimum value at the high-altitude locations Shillong and Aizwal. In general, strong seasonality in AOD is observed with a peak in pre-monsoon (March–May) and dip in post-monsoon (October–November) at all the locations. The direct instantaneous TOA shortwave aerosol radiative forcing (SWARF) shows maximum values in pre-monsoon over all the locations except at Guwahati, Banmauk, Aizawl, and Shillong. The lowest value of instantaneous SWARF is observed in post-monsoon except at Banmauk and Shillong. Climatologically TOA diurnally averaged SWARF varies between −6.95 W m−2 in Aizawl to −20.39 W m−2 in Shillong. In general, the TOA SW forcing efficiency is highest in monsoon at all the locations. The radiative forcing efficiency is found to be less negative when surface reflectance increases. © 2017 Royal Meteorological Society"
"55809001300;6507435338;27267529400;57190001768;16444265000;7003430284;36194896400;7004027519;6701313597;56543138800;7003908632;","Airborne observations of far-infrared upwelling radiance in the Arctic",2016,"10.5194/acp-16-15689-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007008688&doi=10.5194%2facp-16-15689-2016&partnerID=40&md5=55edf296773a176d01b8d74608a1f492","The first airborne measurements of the Far-InfraRed Radiometer (FIRR) were performed in April 2015 during the panarctic NETCARE campaign. Vertical profiles of spectral upwelling radiance in the range 8-50 μm were measured in clear and cloudy conditions from the surface up to 6 km. The clear sky profiles highlight the strong dependence of radiative fluxes to the temperature inversion typical of the Arctic. Measurements acquired for total column water vapour from 1.5 to 10.5 mm also underline the sensitivity of the far-infrared greenhouse effect to specific humidity. The cloudy cases show that optically thin ice clouds increase the cooling rate of the atmosphere, making them important pieces of the Arctic energy balance. One such cloud exhibited a very complex spatial structure, characterized by large horizontal heterogeneities at the kilometre scale. This emphasizes the difficulty of obtaining representative cloud observations with airborne measurements but also points out how challenging it is to model polar clouds radiative effects. These radiance measurements were successfully compared to simulations, suggesting that state-of-the-art radiative transfer models are suited to study the cold and dry Arctic atmosphere. Although FIRR in situ performances compare well to its laboratory performances, complementary simulations show that upgrading the FIRR radiometric resolution would greatly increase its sensitivity to atmospheric and cloud properties. Improved instrument temperature stability in flight and expected technological progress should help meet this objective. The campaign overall highlights the potential for airborne far-infrared radiometry and constitutes a relevant reference for future similar studies dedicated to the Arctic and for the development of spaceborne instruments. © The Author(s) 2016."
"7403282069;8977001000;","Understanding the tropical cloud feedback from an analysis of the circulation and stability regimes simulated from an upgraded multiscale modeling framework",2016,"10.1002/2016MS000767","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006287864&doi=10.1002%2f2016MS000767&partnerID=40&md5=b6a561d44ed6b8417e2b52b7d6ee8c0f","As revealed from studies using conventional general circulation models (GCMs), the thermodynamic contribution to the tropical cloud feedback dominates the dynamic contribution, but these models have difficulty in simulating the subsidence regimes in the tropics. In this study, we analyze the tropical cloud feedback from a 2 K sea surface temperature (SST) perturbation experiment performed with a multiscale modeling framework (MMF). The MMF explicitly represents cloud processes using 2-D cloud-resolving models with an advanced higher-order turbulence closure in each atmospheric column of the host GCM. We sort the monthly mean cloud properties and cloud radiative effects according to circulation and stability regimes. We find that the regime-sorted dynamic changes dominate the thermodynamic changes in terms of the absolute magnitude. The dynamic changes in the weak subsidence regimes exhibit strong negative cloud feedback due to increases in shallow cumulus and deep clouds while those in strongly convective and moderate-to-strong subsidence regimes have opposite signs, resulting in a small contribution to cloud feedback. On the other hand, the thermodynamic changes are large due to decreases in stratocumulus clouds in the moderate-to-strong subsidence regimes with small opposite changes in the weak subsidence and strongly convective regimes, resulting in a relatively large contribution to positive cloud feedback. The dynamic and thermodynamic changes contribute equally to positive cloud feedback and are relatively insensitive to stability in the moderate-to-strong subsidence regimes. But they are sensitive to stability changes from the SST increase in convective and weak subsidence regimes. These results have implications for interpreting cloud feedback mechanisms. Published 2016. This article is a U.S. Government work and is in the public domain in the USA."
"36456423100;7203047936;","Uncertainty in Fengyun-3C Microwave Humidity Sounder Measurements at 118 GHz With Respect to Simulations From GPS RO Data",2016,"10.1109/TGRS.2016.2587878","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983611770&doi=10.1109%2fTGRS.2016.2587878&partnerID=40&md5=e958e0036bc63c2dd5abfb549fd4d608","Microwave Humidity Sounder (MWHS) onboard the Chinese FengYun-3C satellite has a total of 12 channels. Eight of these channels are located near the 118-GHz oxygen absorption band for probing atmospheric temperature and humidity fields from space. While the water vapor sounding channels near 183 GHz have been extensively studied in the past, we report the first satellite observations at 118 GHz. In this paper, the MWHS calibration accuracy is assessed by comparing the satellite observations with simulations. Using the collocated Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) radio occultation (RO) data in clear-sky conditions as inputs to Community Radiative Transfer Model, MWHS brightness temperatures are simulated for the five upper level sounding channels 2-9 located near the 118-GHz oxygen absorption band. For quality control of clear-sky radiance, a new cloud index is first developed based on the two MWHS window channels 1 and 10. Monthly mean biases of the antenna brightness temperature observations for the 118-GHz sounding channels are quantified by using more than 2000-5000 collocated COSMIC and MWHS data from August 2014 to February 2015. It is found that the bias of MWHS data relative to COSMIC RO simulation is dependent on channel and ranges within ±1.5 K. The standard deviation from the bias is the largest at MWHS channel 2, indicating a larger variability of the measurements of channel 2 than the other channels. © 2016 IEEE."
"14630194200;6602080205;37056101400;","A case study of the radiative effect of aerosols over Europe: EUCAARI-LONGREX",2016,"10.5194/acp-16-7639-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976271625&doi=10.5194%2facp-16-7639-2016&partnerID=40&md5=c6640e84e6314936190ed0e001e439be","The radiative effect of anthropogenic aerosols over Europe during the 2008 European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions Long Range Experiment (EUCAARI-LONGREX) campaign has been calculated using measurements collected by the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft and radiative transfer modelling. The aircraft sampled anthropogenically perturbed air masses across north-western Europe under anticyclonic conditions with aerosol optical depths ranging from 0.047 to 0.357. For one specially designed ""radiative closure"" flight, simulated irradiances have been compared to radiation measurements for a case of aged European aerosol in order to explore the validity of model assumptions and the degree of radiative closure that can be attained given the spatial and temporal variability of the observations and their measurement uncertainties. Secondly, the diurnally averaged aerosol radiative effect throughout EUCAARI-LONGREX has been calculated. The surface radiative effect ranged between -3.9 and -22.8Wm-2 (mean -11±5Wm-2), whilst top-of-the-atmosphere (TOA) values were between -2.1 and -12.0Wm-2 (mean -5±3Wm-2). We have quantified the uncertainties in our calculations due to the way in which aerosols and other parameters are represented in a radiative transfer model. The largest uncertainty in the aerosol radiative effect at both the surface and the TOA comes from the spectral resolution of the information used in the radiative transfer model (∼ 17%) and the aerosol description (composition and size distribution) used in the Mie calculations of the aerosol optical properties included in the radiative transfer model (∼7%). The aerosol radiative effect at the TOA is also highly sensitive to the surface albedo (∼12%). © Author(s) 2016."
"56265041500;6602574676;57203297300;6603453147;36098286300;","Radiative characteristics of clouds embedded in smoke derived from airborne multiangular measurements",2016,"10.1002/2016JD025309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982938375&doi=10.1002%2f2016JD025309&partnerID=40&md5=4e90d5927460d78ca3d501fb4748a324","Clouds in the presence of absorbing aerosols result in their apparent darkening, observed at the top of atmosphere (TOA), which is associated with the radiative effects of aerosol absorption. Owing to the large radiative effect and potential impacts on regional climate, above-cloud aerosols have recently been characterized in multiple satellite-based studies. While satellite data are particularly useful in showing the radiative impact of above-cloud aerosols at the TOA, recent literature indicates large uncertainties in satellite retrievals of above-cloud aerosol optical depth (AOD) and single scattering albedo (SSA), which are among the most important parameters in the assessment of associated radiative effects. In this study, we analyze radiative characteristics of clouds in the presence of wildfire smoke using airborne data primarily from NASA’s Cloud Absorption Radiometer, collected during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites campaign in Canada during the 2008 summer season. We found a strong positive reflectance (R) gradient in the UV-visible (VIS)-near infrared (NIR) spectrum for clouds embedded in dense smoke, as opposed to an (expected) negative gradient for cloud-free smoke and a flat spectrum for smoke-free cloud cover. Several cases of clouds embedded in thick smoke were found, when the aircraft made circular/spiral measurements, which not only allowed the complete characterization of angular distribution of smoke scattering but also provided the vertical distribution of smoke and clouds (within 0.5-5 km). Specifically, the largest darkening by smoke was found in the UV/VIS, with R0.34µm reducing to 0.2 (or 20%), in contrast to 0.8 at NIR wavelengths (e.g., 1.27 µm). The observed darkening is associated with large AODs (0.5-3.0) and moderately low SSA (0.85-0.93 at 0.53 µm), resulting in a significantly large instantaneous aerosol forcing efficiency of 254 ± 47Wm-2 τ-1. Our observations of smoke-cloud radiative interactions were found to be physically consistent with theoretical plane-parallel 1-D and Monte Carlo 3-D radiative transfer calculations, capturing the observed gradient across UV-VIS-NIR. Results from this study offer insights into aerosol-cloud radiative interactions and may help in better constraining satellite retrieval algorithms. © 2016. American Geophysical Union. All Rights Reserved."
"57212023257;57212026400;","A Preliminary Evaluation of Global and East Asian Cloud Radiative Effects in Reanalyses",2015,"10.3878/AOSL20140093","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075732117&doi=10.3878%2fAOSL20140093&partnerID=40&md5=e3c4a639ba50df297370bd3c73cd5bbc","Cloud radiative effects (CREs) at the top of the atmosphere (TOA) in three reanalysis datasets (the European Center for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), the Japanese 55-yr Reanalysis Project (JRA-55), and the Modern-Era Retrospective Analysis for Research and Applications (MERRA)) are evaluated using recent satellite-based observations. The reanalyses can basically capture the spatial pattern of the annual mean shortwave CRE, but the global mean longwave CRE in ERA-Interim and JRA55 is weaker than observed, leading to overestimations of the net CRE. Moreover, distinct CRE biases of the reanalyses occur in the Intertropical Convergence Zone (ITCZ), coastal Pacific and Atlantic regions, and East Asia. Quantitative examination further indicates that the spatial correlations of CREs and TOA upward radiation fluxes with corresponding observations in ERA-Interim are better than in the other two reanalyses. Although MERRA has certain abilities in producing the magnitudes of global mean CREs, its performance in terms of spatial correlations in winter and summer are worse than for the other two reanalyses. The ability of JRA55 in reflecting CREs lies between the other two datasets. Compared to the global mean results, the spatial correlations of shortwave CRE in East Asia decrease and the biases of regional mean CREs increase in the three reanalyses. This implies that, currently, it is still difficult to reproduce East Asian CREs based on these reanalyses. Relatively, ERA-Interim describes the seasonal variation of East Asian CREs well, albeit weaker than observed. The present study also suggests that in-depth exploration of the ability of reanalysis data to describe aspects relating to cloud properties and radiation is needed using more comprehensive observations. © 2015, © Institute of Atmospheric Physics, Chinese Academy of Sciences."
"56919065500;7005685786;","Case study of moisture and heat budgets within atmospheric rivers",2015,"10.1175/MWR-D-15-0006.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84945151645&doi=10.1175%2fMWR-D-15-0006.1&partnerID=40&md5=116df6ecf1aea23b29c8de118cd42f9b","This work studies moisture and heat budgets within two atmospheric rivers (ARs) that made landfall on the west coast of North America during January 2009. Three-dimensional kinematic and thermodynamic fields were constructed using ECMWF Year of Tropical Convection data and global gridded precipitation datasets. Differences between the two ARs are observed, even though both had embedded precipitating convective organizations of the same spatial scale. AR1 extended from 20� to 50�N in an almost west-east orientation. It had excessive warm and moist near-surface conditions. Its precipitating systems were mainly distributed on the southwest and northeast sides of the AR, and tended to exhibit stratiform-type vertical heat and moisture transports. In contrast, AR2 spanned latitudes between 20� and 60�N in a north-south orientation. It was narrower and shorter than AR1, and was mostly covered by pronounced precipitating systems, dominated by a deep convection type of heating throughout the troposphere. In association with these distinctions, the atmosphere over the northeastern Pacific on average experienced episodic cooling and drying despite the occurrence of AR1, yet underwent heating and drying during AR2, when latent heating was strong. Downward sensible heat flux and weak upward surface latent heat flux were observed particularly in AR1. In addition, cloud radiative forcing (CRF) was very weak in AR1, whereas it was strongly negative in AR2. In short, it is found that the oceanic convection in ARs both impacts the moisture transport of ARs, as well as modifies the heat balance in the midlatitudes through latent heat release, convective heat transport, surface heat fluxes, and CRF. � 2015 American Meteorological Society."
"57194851498;35768617200;7202607188;57203053317;7102011023;","Did the 2011 Nabro eruption affect the optical properties of ice clouds?",2015,"10.1002/2015JD023326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944929911&doi=10.1002%2f2015JD023326&partnerID=40&md5=ef4435db05dfdc466ffd0ee9adcfe682","The eruption of the Eritrean Nabro Volcano in June 2011 was the largest eruption since Mount Pinatubo in June 1991. The Nabro volcano emitted 1-1.5 megaton of sulfur dioxide into the lower stratosphere which resulted in a significant rise in the stratospheric sulfate aerosol burden in the months following the eruption. We have analyzed backscatter and extinction from ice clouds, as measured by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite between June 2006 and May 2014, to assess if volcanic aerosol produced by the Nabro eruption had affected ice clouds. We found no significant modifications of either of ice cloud optical properties (i.e., total backscattering and extinction), occurrence frequencies, or residence altitudes on a global scale. Using the analyzed optical properties as indicators of posteruptive ice cloud radiative forcing modifications, we find that the eruption had no significant volcanic aerosol-ice cloud radiative effect. Our results suggest that the investigated optical properties of ice and cirrus clouds are at most weakly dependent on the sulfate droplet number density and size distribution. © 2015. American Geophysical Union. All Rights Reserved."
"55389942900;6701815637;6603566335;","Impact of changes in the formulation of cloud-related processes on model biases and climate feedbacks",2014,"10.1002/2014MS000341","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027918346&doi=10.1002%2f2014MS000341&partnerID=40&md5=91d78f6fedae273aff1a8a79996dce81","To test the impact of modeling uncertainties and biases on the simulation of cloud feedbacks, several configurations of the EC-Earth climate model are built altering physical parameterizations. An overview of the various radiative feedbacks diagnosed from the reference EC-Earth configuration is documented for the first time. The cloud feedback is positive and small. While the total feedback parameter is almost insensitive to model configuration, the cloud feedback, in particular its shortwave (SW) component, can vary considerably depending on the model settings. The lateral mass exchange rate of penetrative convection and the conversion rate from condensed water to precipitation are leading uncertain parameters affecting the radiative feedbacks diagnosed. Consistent with other studies, we find a strong correlation between low-cloud model fidelity and low-cloud response under global warming. It is shown that this relationship holds only for stratocumulus regimes and is contributed by low-cloud cover, rather than low-cloud optical thickness. Model configurations simulating higher stratocumulus cover, which is closer to the observations, exhibit a stronger positive SW cloud feedback. This feedback is likely underestimated in the reference EC-Earth configuration, over the eastern basins of the tropical oceans. In addition, connections between simulated high-cloud top altitude in present-day climate and longwave cloud feedback are discussed. © 2014. The Authors."
"29467691000;7005135473;7404747615;","Multiplatform analysis of the radiative effects and heating rates for an intense dust storm on 21 June 2007",2013,"10.1002/jgrd.50713","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885088469&doi=10.1002%2fjgrd.50713&partnerID=40&md5=0973cc4a1798c4e09f9414613ccff302","Dust radiative effects and atmospheric heating rates are investigated for a Saharan dust storm on 21 June 2007 using a combination of multiple satellite data sets and ground and aircraft observations as input into a delta-four stream radiative transfer model (RTM). This combines the strengths of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations and CloudSat satellites and in situ aircraft data to characterize the vertical structure of the dust layers (5 km in height with optical depths between 1.5 and 2.0) and underlying low-level water clouds. These observations were used, along with Aerosol Robotic Network retrievals of aerosol optical properties, as input to the RTM to assess the surface, atmosphere, and top of atmosphere (TOA) shortwave aerosol radiative effects (SWAREs). Our results show that the dust TOA SWARE per unit aerosol optical depth was -56 W m-2 in cloud-free conditions over ocean and +74 W m-2 where the dust overlay low-level clouds, and show heating rates greater than 10 K/d. Additional case studies also confirm the results of the 21 June case. This study shows the importance of identifying clouds beneath dust as they can have a significant impact on the radiative effects of dust, and hence assessments of the role of dust aerosol on the energy budget and climate. © 2013. Her Majesty the Queen in Right of Canada. American Geophysical Union."
"7403625607;52264136000;8968548000;7006495234;","An efficient and effective method to simulate the earth spectral reflectance over large temporal and spatial scales",2013,"10.1002/grl.50116","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874885845&doi=10.1002%2fgrl.50116&partnerID=40&md5=2217ccea665f6ea1673705d337628b4c","Atmospheric and surface properties have been measured from space with various spatial resolutions for decades. It is very challenging to derive the mean solar spectral radiance or reflectance over large temporal and spatial scales by explicit radiative transfer computations from the large volume of instantaneous data, especially at high spectral resolution. We propose a procedurally simple but effective method to compute the solar spectral reflectance in large climate domains, in which the probability distribution function (PDF) of cloud optical depth is used to account for the wide variation of cloud properties in different sensor footprints, and to avoid the repeated computations for footprints with similar conditions. This approach is tested with MODIS/CERES data and evaluated with SCIAMACHY measured spectral reflectance. The mean difference between model and observation is about 3% for the monthly global mean reflectance. This PDF-based approach provides a simple, fast, and effective way to simulate the mean spectral reflectance over large time and space scales with a large volume of high-resolution satellite data. © 2013. American Geophysical Union. All Rights Reserved."
"55541379500;23970271800;15726335100;57207603330;","Evaluation of the shortwave cloud radiative effect over the ocean by use of ship and satellite observations",2012,"10.5194/acp-12-12243-2012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84871725714&doi=10.5194%2facp-12-12243-2012&partnerID=40&md5=cac51e74f797030cc51a9886b03ce6cf","In this study the shortwave cloud radiative effect (SWCRE) over ocean calculated by the ECHAM 5 climate model is evaluated for the cloud property input derived from ship based measurements and satellite based estimates and compared to ship based radiation measurements. The ship observations yield cloud fraction, liquid water path from a microwave radiometer, cloud bottom height as well as temperature and humidity profiles from radiosonde ascents. Level-2 products of the Satellite Application Facility on Climate Monitoring (CM∼SAF) from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) have been used to characterize clouds. Within a closure study six different experiments have been defined to find the optimal set of measurements to calculate downward shortwave radiation (DSR) and the SWCRE from the model, and their results have been evaluated under seven different synoptic situations. Four of these experiments are defined to investigate the advantage of including the satellite-based cloud droplet effective radius as additional cloud property. The modeled SWCRE based on satellite retrieved cloud properties has a comparable accuracy to the modeled SWCRE based on ship data. For several cases, an improvement through introducing the satellite-based estimate of effective radius as additional information to the ship based data was found. Due to their different measuring characteristics, however, each dataset shows best results for different atmospheric conditions. © 2012 Author(s)."
"29867471100;6603383696;","Interfacing a one-dimensional lake model with a single-column atmospheric model: 2. Thermal response of the deep Lake Geneva, Switzerland under a 2 × CO2 global climate change",2012,"10.1029/2011WR011222","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84862556863&doi=10.1029%2f2011WR011222&partnerID=40&md5=8151f473f70144faae42aa4d13f19201","In the companion to the present paper, the one-dimensional k-ε lake model SIMSTRAT is coupled to a single-column atmospheric model, nicknamed FIZC, and an application of the coupled model to the deep Lake Geneva, Switzerland, is described. In this paper, the response of Lake Geneva to global warming caused by an increase in atmospheric carbon dioxide concentration (i.e., 2 × CO2) is investigated. Coupling the models allowed for feedbacks between the lake surface and the atmosphere and produced changes in atmospheric moisture and cloud cover that further modified the downward radiation fluxes. The time evolution of atmospheric variables as well as those of the lake's thermal profile could be reproduced realistically by devising a set of adjustable parameters. In a ""control"" 1 × CO2 climate experiment, the coupled FIZC-SIMSTRAT model demonstrated genuine skills in reproducing epilimnetic and hypolimnetic temperatures, with annual mean errors and standard deviations of 0.25°C ± 0.25°C and 0.3°C ± 0.15°C, respectively. Doubling the CO2 concentration induced an atmospheric warming that impacted the lake's thermal structure, increasing the stability of the water column and extending the stratified period by 3 weeks. Epilimnetic temperatures were seen to increase by 2.6°C to 4.2°C, while hypolimnion temperatures increased by 2.2°C. Climate change modified components of the surface energy budget through changes mainly in air temperature, moisture, and cloud cover. During summer, reduced cloud cover resulted in an increase in the annual net solar radiation budget. A larger water vapor deficit at the air-water interface induced a cooling effect in the lake. © 2012 American Geophysical Union. All Rights Reserved."
"6603250042;36165094300;","The impact of a non-uniform land surface on the radiation environment over an Arctic fjord - A study with a 3D radiative transfer model for stratus clouds over the Hornsund fjord, Spitsbergen",2012,"10.5697/oc.54-4.509","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84869803785&doi=10.5697%2foc.54-4.509&partnerID=40&md5=bc563e0c41a7be3b897848adf26722bf","This paper estimates the influence of land topography and cover on 3D radiative effects under overcast skies in the Arctic coastal environment, in particular in the Hornsund fjord region, Spitsbergen. The authors focus on the impact of a non- uniform surface on: (1) the spatial distribution of solar fluxes reaching the fjord surface, (2) spectral shortwave cloud radiative forcing at the fjord surface, (3) the solar flux anomaly at the domain surface resulting from the assumption of a uniform surface, i.e. the error due to plane parallel assumptions in climate models, and (4) remote sensing of cloud optical thickness over the fjord. Their dependence on spectral channel, cloud optical thickness, cloud type, cloud base height, surface albedo and solar zenith angle is discussed. The analysis is based on Monte Carlo simulations of solar radiation transfer over a heterogeneous surface for selected channels of the MODIS radiometer. The simulations showed a considerable impact of the land surrounding the fjord on the solar radiation over the fjord. The biggest differences between atmospheric transmittances over the fjord surface and over the ocean were found for a cloud optical thickness τ=12, low solar zenith angle ν, high cloud base and snow-covered land. For τ =12, ν=53°, cloud base height 1.8 km and wavelength λ =469 nm, the enhancement in irradiance transmittance over the fjord was 0.19 for the inner fjords and 0.10 for the whole fjord (λ =469 nm). The land surrounding the Hornsund fjord also had a considerable impact on the spectral cloud radiative forcing on the fjord surface and the solar flux anomaly at the domain surface due to the uniform surface assumption. For the mouth and central part of the fjord the error due to the use of channel 2 of the MODIS radiometer (λ =858 nm) for cloud optical thickness retrieval was <1 in the case of low-level clouds (cloud base height 1 km, nadir radiance, ν=53°, cloud optical thickness retrieved solely from MODIS channel 2). However, near the shoreline (up to 2 km from it), especially over the inner fjords, the cloud optical thickness was then overestimated by >3 for τ =5 and by >5 for τ =20. © Polish Academy of Sciences, Institute of Oceanology, 2012."
"56615268500;7004357137;16444240700;7004167838;","Application of an adaptive radiative transfer scheme in a mesoscale numerical weather prediction model",2012,"10.1002/qj.890","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856225448&doi=10.1002%2fqj.890&partnerID=40&md5=296eb856e376d97469a5669e85129d3e","The computational burden of radiative transfer parametrization is considerable, and hence operational atmospheric models use various sampling, coarsening and interpolation techniques to reduce this load; this, however, introduces new errors. An adaptive radiative transfer scheme takes advantage of the spatial and temporal correlations in the optical characteristics of the atmosphere to make the parametrization computationally more efficient. The adaptive scheme employed here generalizes the accurate radiation computations made in a fraction of the spatial and temporal space to the rest of the field. In this study, a previously developed scheme has been extended to atmospheric heating rates and implemented in the numerical weather prediction model COSMO. The performance of the adaptive scheme is compared with the performance of the currently operational COSMO-DE radiation configuration, in which radiation computations are performed quarter-hourly on 2 × 2 averaged atmospheric columns. The reference for both schemes is a set of frequent radiation computations for the full grid. We show that the adaptive scheme is able to reduce the sampling errors in the radiation surface fluxes by 15-25% and to conserve the spatial variability, in contrast to the operational scheme. Deviations in the heating-rate profiles are reduced for larger averaging scales. Physical relationships between the radiative quantities and cloud water or rain rates are better captured. We demonstrate that these improvements also lead to improvements with respect to the dynamical development of the model simulation, showing a smaller divergence from the reference model run. © 2011 Royal Meteorological Society."
"23492365000;14009374600;57192504228;57215373843;","Estimation of land surface temperature and emissivity from AMSR-E data",2007,"10.1109/IGARSS.2007.4423183","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955579163&doi=10.1109%2fIGARSS.2007.4423183&partnerID=40&md5=b73dd4f615c300e544682e0bbe6f27e0","A radiative transfer model to compute brightness temperatures in the microwave region for the soil-vegetationatmosphere system has been developed in this study. Considering the various atmospheric conditions, a microwave brightness temperature database is generated for a wide range of surface dielectric constant and roughness properties under AMSR-E sensor configurations by using the soil-vegetation-atmosphere radiative transfer model. From the land surface emissivities in the simulated database, the linear relationships of surface emissivities between different channels for the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) are established in this study. The analysis of the stability and the root-mean-square error (RMSE) for these linear relations indicates that the relationship using three channels is the best of all. The cloud-free AMSR-E actual satellite microwave data combining with MODIS land surface temperature product are used to validate these relationships. The linear relationship derived from the simulated database is in agreement with that from AMSR-E data. This emissivity model as a constrain condition of the radiative transfer equation is applied to retrieval LST and emissivity, and the RMSE of the results is lower than 1K for LST, 0.0025 for emissivity. So the relationships of emissivity between different channels are very useful to derive land surface parameters directly from AMSR-E data, which will promote the application of AMSR-E data in many fields, such as climate, hydrology, and ecology. © 2007 IEEE."
"16550871500;57197334483;7201361035;","Long-time global radiation for Central Europe derived from ISCCP Dx data",2007,"10.5194/acp-7-5021-2007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34848889543&doi=10.5194%2facp-7-5021-2007&partnerID=40&md5=49b7afbeb5c5f8e9ba64393022ebad9f","The global Dx dataset of the International Satellite Cloud Climatology Project (ISCCP) with a spatial resolution of about 30×30km2 was analysed to produce spatially highly resolved long-time datasets to describe the radiation budget for Central Europe over the period of 1984-2000. The computation of shortwave and longwave radiant flux densities at top of atmosphere and at surface was based on ID radiative transfer simulations. The simulations were carried out for all relevant atmospheric and surface conditions and the results were inserted into a look-up table. Thus, longtime calculations for all conditions and time slices of the Dx dataset could be realised. The study is focussed on the global radiation at surface. The first examination was carried out for the ISCCP Dl and the ISCCP D2 dataset. These datasets, including cloud and surface information on a different spatial scale (280×280 km2), were applied to the produced look-up table analogue to the Dx data. The calculated global radiation of the Dl and D2 dataset were compared to the Dx dataset. The differences between these datasets mainly range from 5-15 Wm-2 (2-6%) with regional peaks up to 25 Wm-2 (10%). The evaluation with the GEWEX Surface Radiation Budget (SRB) data emphasises differences between 5-25 Wm-2 (6-16%) over land areas. Deviations to an ISCCP provided flux data set vary from 0 Wm-2 in the North up to 35 Wm-2 (0-13%) in the South of Central Europe. The global radiation datasets provided by the Global Energy Balance Archive (GEBA) and the German Meteorological Service (DWD) agree well, but they are 5-25 Wm-2 (7-10%) lower than the Dx results. Annual analyses of global radiation of various regional climate models complete the study. It is figured out that the used models and methods reveal a couple of discrepancies. Especially in wintertime the results of our analysis differ to the considered models. Principally the uncertainties were caused by the determined range of values and simplifications for the computation of the radiative transfer simulation."
"55896920900;6603892183;","Introduction to the EUCREX-94 mission 206",2000,"10.1016/S0169-8095(00)00053-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033850677&doi=10.1016%2fS0169-8095%2800%2900053-3&partnerID=40&md5=9249f78a4c87555b708535b73402ce7b","Part of the EUCREX-94 experiment was devoted to the study of the radiative properties of boundary layer clouds in relation with their microphysical and structural properties. Mission 206, on April 18, is particularly attractive because of a general trend in cloud geometrical thickness within the sampled region, with corresponding values of optical thickness between 4 and 70. The cloud system has been extensively documented in situ with an instrumented aircraft, while two other aircraft were measuring its radiative properties with radiometers and a lidar. This paper introduces the scientific objectives of the experiment and describes the instrumental setup. After a presentation of the meteorological situation, the various papers of this series are briefly introduced. (C) 2000 Elsevier Science B.V. All rights reserved."
"6701387222;11440653000;7402899368;","A parameterization of radiative fluxes suitable for use in a statistical-dynamical model",1998,"10.1007/BF01025181","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0040757478&doi=10.1007%2fBF01025181&partnerID=40&md5=c87d2e12e9855531f1ee89c3463b7b5c","A parameterization of shortwave and longwave radiation fluxes derived from detailed radiative transfer models is included in a global primitive equation statistical-dynamical model (SDM) with two hulk atmospheric layers. The model is validated comparing the model simulations with the observed mean annual and seasonal zonally averaged climate. The results show that the simulation of the shortwave and longwave radiation fluxes matches well with the observations. The SDM variables such as surface and 500hPa temperatures, zonal winds at 250hPa and 750hPa, vertical velocity at 500hPa and precipitation are also in good agreement with the observations. A comparison between the results obtained with the present SDM and those with the previous version of the model indicates that the model results improved when the parameterization of the radiative fluxes based on detailed radiative transfer models are included into the SDM. The SDM is used to investigate its response to the greenhouse effect. Sensitivity experiments regarding the doubling of CO2 and the changing of the cloud amount and height are performed. In the case 2×CO2 the model results are consistent with those obtained from GCMs, showing a warming of the climate system. An enhancement of the greenhouse effect is also noted when the cloud layer is higher. However, an increase of the cloud amount in all the latitude belts provokes an increase of the surface temperature near poles and a decrease in all the other regions. This suggests that the greenhouse effect overcomes the albedo effect in the polar latitudes and the opposite occurs in other regions. In all the experiments the changes in the surface temperature are larger near poles, mainly in the Southern Hemisphere."
"57197226964;7103293232;","Validation of downwelling longwave computations with surface measurements during FIFE 89",1995,"10.1029/95jd00385","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029500844&doi=10.1029%2f95jd00385&partnerID=40&md5=0ea51b08d50842fe0baace807f7b8c3d","The amount of longwave radiation reaching the surface is a necessary parameter for climate modeling. As no extensive array of surface-based stations exists for monitoring the downwelling longwave surface flux (F ↓ (0)), satellite, computations of F ↓ (0) need to be validated with surface measurements. In this study the validation of computations of F ↓ (0) is carried out for both clear and cloudy conditions using data from the 1989 phase of the First ISLSCP Field Experiment (FIFE 89). FIFE 89 data is particularly useful for this study, as it contains lidar measuements of cloud base height and cloud fraction, thereby eliminating the need to estimate these parameters from other available data. -Authors"
"7404142321;57197016522;13402835300;","Use of Short-Range Forecasts to Evaluate Fast Physics Processes Relevant for Climate Sensitivity",2020,"10.1029/2019MS001986","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083969524&doi=10.1029%2f2019MS001986&partnerID=40&md5=1d732c30d29f4b0f43ad6bd22ff04120","The configuration of the Met Office Unified Model being submitted to CMIP6 has a high climate sensitivity. Previous studies have suggested that the impact of model changes on initial tendencies in numerical weather prediction (NWP) should be used to guide their suitability for inclusion in climate models. In this study we assess, using NWP experiments, the atmospheric model changes which lead to the increased climate sensitivity in the CMIP6 configuration, namely, the replacement of the aerosol scheme with GLOMAP-mode and the introduction of a scheme for representing the turbulent production of liquid water within mixed-phase cloud. Overall, the changes included in this latest configuration were found to improve the initial tendencies of the model state variables over the first 6 hr of the forecast, this timescale being before significant dynamical feedbacks are likely to occur. The reduced model drift through the forecast appears to be the result of increased cloud liquid water, leading to enhanced radiative cooling from cloud top and contributing to a stronger shortwave cloud radiative effect. These changes improve the 5-day forecast in traditional metrics used for numerical weather prediction. This study was conducted after the model was frozen and the climate sensitivity of the model determined; hence, it provides an independent test of the model changes contributing to the higher climate sensitivity. The results, along with the large body process-orientated evaluation conducted during the model development process, provide reassurance that these changes are improving the physical processes simulated by the model. ©2020. The Authors."
"55777759900;56261301800;16425609300;57202921054;56250119900;","The state of the atmosphere in the 2016 southern Kerguelen Axis campaign region",2020,"10.1016/j.dsr2.2019.02.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062303272&doi=10.1016%2fj.dsr2.2019.02.001&partnerID=40&md5=fc0a63b48940418e6a2c1cbf1eba2946","The near-surface environment of the Southern Ocean is subject to particular biases in weather and climate simulations, particularly during the summer season, and relatively few analyses of cloud and radiation properties have been reported for the region. Here we provide an analysis of ship-based measurements of downwelling radiation, cloud fraction and cloud base height from the RSV Aurora Australis during the Kerguelen Axis marine science campaign which was conducted in the Southern Ocean south-east of the Kerguelen Plateau between January and March 2016. Our study period focussed on a 22-day interval during the first two months of the campaign. We compared estimates of cloud fraction obtained with a cloud imager and ceilometer, and found good agreement between the two measurement types, particularly when the camera images were analysed in a narrow overhead field to account for differences in the measurement techniques. We used the Interim European Centre for Medium-Range Weather Forecasts Reanalysis (ERA-Interim) and the Antarctic Mesoscale Prediction System Polar Weather and Research Forecasting model (Polar WRF) to provide comparison data for our measurements. We found that both comparison data sets generally underestimated cloud cover (observed cloud fraction ~0.96 compared with 0.87 for ERA-Interim and 0.63 for Polar WRF). As a consequence, the comparison data showed biases in both the surface shortwave irradiance (+59 W m−2 for ERA-Interim and +154 W m−2 for Polar WRF) and the longwave irradiance (−23 W m−2 for ERA-Interim and −46 W m−2 for Polar WRF). The observed mean net surface cloud radiative effect (CRE) of −228 W m−2 was significantly more negative than found in previous observations in the Southern Ocean region, and compares with a net surface CRE of − 138 W m−2 for ERA-Interim which also showed relatively strong cloud forcing. The observed net surface CRE bias for ERA-Interim of + 90 W m−2 appears primarily the result of the reanalysis underestimating the cloud fraction, which at least partly relates to a lack of low clouds. Polar WRF was also found to have a deficit of low clouds. We characterised the relationship between the ratio of irradiances by Photosynthetically Active Radiation (PAR) and shortwave radiation and cloud transmittance. As a consequence of cloud, light levels were estimated as being below the level for light-limited photosynthesis during 31% of the available time the sun was above the horizon (69% of each day on average), compared with the expected clear-sky value of 10%. Over the campaign period, the Indian Ocean sector of the Southern Ocean was influenced by the positive phase of the Southern Annular Mode (SAM). Notably, the surface SAM index in January and March was the most positive observed since 1957. This situation generally led to near-surface climatological differences over the southern part of the campaign region over much of the period, which included significant negative anomalies in mean sea level pressure and air temperature, and positive anomalies in zonal wind. Overall, the cloudiness of our study region appeared to be above average for the time of year, but we could not identify a clear cause for this in the prevailing climatic conditions. While the level of shortwave radiation was likely below average for the time of year, this deficit is not likely to have significantly impacted on photosynthesis in the mixed layer of the ocean. © 2019 Elsevier Ltd"
"57190428630;57211388004;57199180112;57214884613;57205648307;57214889457;55303055600;57191036453;11340215800;8581523500;","Retrieval of gridded aerosol direct radiative forcing based on multiplatform datasets",2020,"10.5194/amt-13-575-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079372265&doi=10.5194%2famt-13-575-2020&partnerID=40&md5=4c2a2568060c3de7e9bb44f3d6cdbffc","Atmospheric aerosols play a crucial role in regional radiative budgets. Previous studies on clear-sky aerosol direct radiative forcing (ADRF) have mainly been limited to site-scale observations or model simulations for short-term cases, and long-term distributions of ADRF in China have not been portrayed yet. In this study, an accurate fine-resolution ADRF estimate at the surface was proposed. Multiplatform datasets, including satellite (MODIS aboard Terra and Aqua) and reanalysis datasets, served as inputs to the Santa Barbara Discrete Atmospheric Radiative Transfer (SBDART) model for ADRF simulation with consideration of the aerosol vertical profile over eastern China during 2000-2016. Specifically, single-scattering albedo (SSA) from the Modern-Era Retrospective Analysis for Research and Application, Version 2 (MERRA-2) was validated with sun photometers over eastern China. The gridded asymmetry parameter (ASY) was then simulated by matching the calculated top-of-atmosphere (TOA) radiative fluxes from the radiative transfer model with satellite observations (Clouds and the Earth's Radiant Energy System, CERES). The high correlation and small discrepancy (6-8Wm-2) between simulated and observed radiative fluxes at three sites (Baoshan, Fuzhou, and Yong'an) indicated that ADRF retrieval is feasible and has high accuracy over eastern China. Then this method was applied in each grid of eastern China, and the overall picture of ADRF distributions over eastern China during 2000-2016 was displayed. ADRF ranges from -220 to -20Wm-2, and annual mean ADRF is -100.21Wm-2, implying that aerosols have a strong cooling effect at the surface in eastern China. With the economic development and rapid urbanization, the spatiotemporal changes of ADRF during the past 17 years are mainly attributed to the changes of anthropogenic emissions in eastern China. Our method provides the long-term ADRF distribution over eastern China for the first time, highlighting the importance of aerosol radiative impact under climate change. © 2020 SPIE. All rights reserved."
"57193328365;26645901500;7004468723;57112070700;23012746800;36187387300;","Robustness and drivers of the Northern Hemisphere extratropical atmospheric circulation response to a CO 2 -induced warming in CNRM-CM6-1",2020,"10.1007/s00382-019-05113-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078242158&doi=10.1007%2fs00382-019-05113-4&partnerID=40&md5=032c9124f045bc4c003e34167af3a915","Understanding the mid-latitude atmospheric circulation response to CO2 forcing is challenging and complex due to the strong internal variability and the multiple potential CO2-induced effects. While a significant poleward shift of the jet is projected in summer, changes remain uncertain in winter. In this study, we investigate the boreal winter extratropical jet response to an abrupt quadrupling of atmospheric CO2 in the CMIP6-generation global climate model CNRM-CM6-1. First, we show that the model performs better than the former generation CNRM-CM5 model in representing the atmospheric dynamics in the northern extratropics. Then, when atmospheric CO2 is quadrupled, CNRM-CM6-1 exhibits a strengthening and upward shift of the jet. A poleward shift is identified and robust in the Pacific in boreal winter. In the Atlantic, the jet response rather exhibits a squeezing, especially at the eastern part of the basin. It is found that changes are more robust across the Northern Hemisphere in early-winter than in late-winter season. Finally, the circulation response is broken down into individual contributions of various drivers. The uniform global mean component of the SST warming is found to explain most of the total atmospheric response to a quadrupling of CO2, with relatively smaller contributions from faster CO2 effects, the SST pattern change and the Arctic sea ice decline. The cloud radiative effect contribution is also assessed and found to be rather weak in the CNRM-CM6-1 model. This study highlights that long experiments are required to isolate the wintertime circulation response from the internal variability, and that idealized experimental setups are helpful to disentangle the physical drivers. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature."
"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."
"55855888600;","The multi-scale structure of atmospheric energetic constraints on globally averaged precipitation",2019,"10.5194/esd-10-219-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064395081&doi=10.5194%2fesd-10-219-2019&partnerID=40&md5=cfd55fa2b155448a9649aeca17a6508c","This study presents a multi-scale analysis of cross-correlations based on Haar fluctuations of globally averaged anomalies of precipitation (P ), precipitable water vapor (PWV), surface temperature (T ), and atmospheric radiative fluxes. The results revealed an emergent transition between weak correlations at subyearly timescales (down to ∼ 5 days) to strong correlations at timescales larger than about ∼ 12 years (up to ∼ 1 decade). At multiyear timescales, (i) ClausiusClapeyron becomes the dominant control of PWV (pPWV;T≈0:9), (ii) surface temperature averaged over global land and over global ocean (sea surface temperature, SST) become strongly correlated (pTland;SST ∼ 0:6); (iii) globally averaged precipitation variability is dominated by energetic constraints, specifically the surface downwelling longwave radiative flux (DLR) (pP;DLR≈-0:8) displayed stronger correlations than the direct response to T fluctuations, and (iv) cloud effects are negligible for the energetic constraints in (iii), which are dominated by clear-sky DLR. At sub-yearly timescales, all correlations underlying these four results decrease abruptly towards negligible values. Such a transition has important implications for understanding and quantifying the climate sensitivity of the global hydrological cycle. The validity of the derived correlation structure is demonstrated by reconstructing global precipitation time series at 2-year resolution, relying on the emergent strong correlations (P vs. clear-sky DLR). Such a simple linear sensitivity model was able to reproduce observed P anomaly time series with similar accuracy to an (uncoupled) atmospheric model (ERA-20CM) and two climate reanalysis (ERA-20C and 20CR). The linear sensitivity breaks down at sub-yearly timescales, whereby the underlying correlations become negligible. Finally, the relevance of the multi-scale framework and its potential for stochastic downscaling applications are demonstrated by deriving accurate monthly P probability density functions (PDFs) from the reconstructed 2- year P time series based on scale-invariant arguments alone. The derived monthly PDFs outperform the statistics simulated by ERA-20C, 20CR, and ERA-20CM in reproducing observations. © 2019 Author(s)."
"35221443100;7501627905;","Background Conditions Influence the Estimated Cloud Radiative Effects of Anthropogenic Aerosol Emissions From Different Source Regions",2019,"10.1029/2018JD029644","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062349403&doi=10.1029%2f2018JD029644&partnerID=40&md5=9513ff3466c433c23260e3f3626b68a9","Using the Community Earth System Model, with the Community Atmosphere Model version 5.3, we investigate the cloud radiative effects of anthropogenic aerosols emitted from different source regions and global shipping. We also analyze aerosol burdens, cloud condensation nuclei concentration, liquid water path, and ice water path. Due to transboundary transport and sublinearity in the response of clouds to aerosols, the cloud radiative effects of emissions from a given source region are influenced by emissions from other source regions. For example, the shortwave cloud radiative effect of shipping is −0.39 ± 0.03 W/m2 when other anthropogenic emissions sources are present (the “present-day background” assumption) compared with −0.60 ± 0.03 W/m2 when other anthropogenic emissions sources are absent (the “natural background” assumption). In general, the cloud radiative effects are weaker if present-day background conditions are assumed compared with if natural background conditions are assumed. Assumptions about background conditions should be carefully considered when investigating the climate impacts of aerosol emissions from a given source region. ©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."
"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."
"55795535700;35494005000;25031430500;","Using A-Train observations to evaluate cloud occurrence and radiative effects in the Community Atmosphere Model during the Southeast Asia summer monsoon",2019,"10.1175/JCLI-D-18-0693.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068052455&doi=10.1175%2fJCLI-D-18-0693.1&partnerID=40&md5=67da1594c914fe6ffefd847d52aafb98","The distribution of clouds and their radiative effects in the Community Atmosphere Model, version 5 (CAM5), are compared to A-Train satellite data in Southeast Asia during the summer monsoon. Cloud radiative kernels are created based on populations of observed and modeled clouds separately in order to compare the sensitivity of the TOA radiation to changes in cloud fraction. There is generally good agreement between the observation- and model-derived cloud radiative kernels for most cloud types, meaning that the clouds in the model are heating and cooling like clouds in nature. Cloud radiative effects are assessed by multiplying the cloud radiative kernel by the cloud fraction histogram. For ice clouds in particular, there is good agreement between the model and observations, with optically thin cirrus producing a moderate warming effect and cirrostratus producing a slight cooling effect, on average. Consistent with observations, the model also shows that the median value of the ice water path (IWP) distribution, rather than the mean, is a more representative measure of the ice clouds that are responsible for heating. In addition, in both observations and the model, it is cirrus clouds with an IWP of 20 gm-2 that have the largest warming effect in this region, given their radiative heating and frequency of occurrence. © 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."
"56190076100;35221443100;36106335800;15318900900;7501627905;","Impacts on cloud radiative effects induced by coexisting aerosols converted from international shipping and maritime DMS emissions",2018,"10.5194/acp-18-16793-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057800870&doi=10.5194%2facp-18-16793-2018&partnerID=40&md5=1e47a88c066f3c55fa9b06421218a764","International shipping emissions (ISE), particularly sulfur dioxide, can influence the global radiation budget by interacting with clouds and radiation after being oxidized into sulfate aerosols. A better understanding of the uncertainties in estimating the cloud radiative effects (CREs) of ISE is of great importance in climate science. Many international shipping tracks cover oceans with substantial natural dimethyl sulfide (DMS) emissions. The interplay between these two major aerosol sources on CREs over vast oceanic regions with a relatively low aerosol concentration is an intriguing yet poorly addressed issue confounding estimation of the CREs of ISE. Using an Earth system model including two aerosol modules with different aerosol mixing configurations, we derive a significant global net CRE of ISE (ĝ'0.153 W mĝ'2 with a standard error of ±0.004 W mĝ'2) when using emissions consistent with current ship emission regulations. This global net CRE would become much weaker and actually insignificant (ĝ'0.001 W mĝ'2 standard error of ±0.007 W mĝ'2) if a more stringent regulation were adopted. We then reveal that the ISE-induced CRE would achieve a significant enhancement when a lower DMS emission is prescribed in the simulations, owing to the sublinear relationship between aerosol concentration and cloud response. In addition, this study also demonstrates that the representation of certain aerosol processes, such as mixing states, can influence the magnitude and pattern of the ISE-induced CRE. These findings suggest a reevaluation of the ISE-induced CRE with consideration of DMS variability. © Author(s) 2018."
"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."
"24472110700;","Spring Arctic atmospheric preconditioning: Do not rule out shortwave radiation just yet",2018,"10.1175/JCLI-D-17-0710.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047061700&doi=10.1175%2fJCLI-D-17-0710.1&partnerID=40&md5=611cb05be32895637c59eb30bebc9c95","Springtime atmospheric preconditioning of Arctic sea ice for enhanced or buffered sea ice melt during the subsequent melt year has received considerable research focus. Studies have identified enhanced poleward atmospheric transport of moisture and heat during spring, leading to increased emission of longwave radiation to the surface. Simultaneously, these studies ruled out the role of shortwave radiation as an effective preconditioning mechanism because of relatively weak incident solar radiation, high surface albedo from sea ice and snow, and increased clouds during spring. These conclusions are derived primarily from atmospheric reanalysis, which may not always accurately represent the Arctic climate system. Here, top-of-atmosphere shortwave radiation observations from a state-of-the-art satellite sensor are compared with ERA-Interim reanalysis to examine similarities and differences in the springtime absorbed shortwave radiation (ASR) over the Arctic Ocean. Distinct biases in regional location and absolute magnitude of ASR anomalies are found between satellite-based measurements and reanalysis. Observations indicate separability between ASR anomalies in spring corresponding to anomalously low and high ice extents in September; the reanalysis fails to capture the full extent of this separability. The causes for the difference in ASR anomalies between observations and reanalysis are considered in terms of the variability in surface albedo and cloud presence. Additionally, biases in reanalysis cloud water during spring are presented and are considered for their impact on overestimating spring downwelling longwave anomalies. Taken together, shortwave radiation should not be overlooked as a contributing mechanism to springtime Arctic atmospheric preconditioning. © 2018 American Meteorological Society."
"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."
"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."
"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."
"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."
"55268661300;55461837700;57196143493;","The influence of atmospheric cloud radiative effects on the large-scale stratospheric circulation",2017,"10.1175/JCLI-D-16-0643.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022334662&doi=10.1175%2fJCLI-D-16-0643.1&partnerID=40&md5=303841430869b0459903ba2d43bbe14e","Previous studies have explored the influence of atmospheric cloud radiative effects (ACRE) on the tropospheric circulation. Here the authors explore the influence of ACRE on the stratospheric circulation. The response of the stratospheric circulation to ACRE is assessed by comparing simulations run with and without ACRE. The stratospheric circulation response to ACRE is reproducible in a range of different GCMs and can be interpreted in the context of both a dynamically driven and a radiatively driven component. The dynamic component is linked to ACRE-induced changes in the vertical and meridional fluxes of wave activity. The ACRE-induced changes in the vertical flux of wave activity into the stratosphere are consistent with the ACRE-induced changes in tropospheric baroclinicity and thus the amplitude of midlatitude baroclinic eddies. They account for a strengthening of the Brewer-Dobson circulation, a cooling of the tropical lower stratosphere, a weakening and warming of the polar vortex, a reduction of static stability near the tropical tropopause transition layer, and a shortening of the time scale of extratropical stratospheric variability. The ACRE-induced changes in the equatorward flux of wave activity in the low-latitude stratosphere account for a strengthening of the zonal wind in the subtropical lower to midstratosphere. The radiative component is linked to ACRE-induced changes in the flux of longwave radiation into the lower stratosphere. The changes in radiative fluxes lead to a cooling of the extratropical lower stratosphere, changes in the static stability and cloud fraction near the extratropical tropopause, and a shortening of the time scales of extratropical stratospheric variability. The results highlight a previously overlooked pathway through which tropospheric climate influences the stratosphere. © 2017 American Meteorological Society."
"57193217667;14009374600;55530911200;35175400200;7409077047;","Estimation of downwelling surface longwave radiation under heavy dust aerosol sky",2017,"10.3390/rs9030207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019360001&doi=10.3390%2frs9030207&partnerID=40&md5=2032e1068a2c9a2c591acc2ecbf79372","The variation of aerosols, especially dust aerosol, in time and space plays an important role in climate forcing studies. Aerosols can effectively reduce land surface longwave emission and re-emit energy at a colder temperature, which makes it difficult to estimate downwelling surface longwave radiation (DSLR) with satellite data. Using the latest atmospheric radiative transfer code (MODTRAN 5.0), we have simulated the outgoing longwave radiation (OLR) and DSLR under different land surface types and atmospheric profile conditions. The results show that dust aerosol has an obvious ""warming"" effect to longwave radiation compared with other aerosols; that aerosol longwave radiative forcing (ALRF) increased with the increasing of aerosol optical depth (AOD); and that the atmospheric water vapor content (WVC) is critical to the understanding of ALRF. A method is proposed to improve the accuracy of DSLR estimation from satellite data for the skies under heavy dust aerosols. The AOD and atmospheric WVC under cloud-free conditions with a relatively simple satellite-based radiation model yielding the high accurate DSLR under heavy dust aerosol are used explicitly as model input to reduce the effects of dust aerosol on the estimation of DSLR. Validations of the proposed model with satellites data and field measurements show that it can estimate the DSLR accurately under heavy dust aerosol skies. The root mean square errors (RMSEs) are 20.4 W/m2 and 24.2 W/m2 for Terra and Aqua satellites, respectively, at the Yingke site, and the biases are 2.7 W/m2 and 9.6 W/m2, respectively. For the Arvaikheer site, the RMSEs are 23.2 W/m2 and 19.8 W/m2 for Terra and Aqua, respectively, and the biases are 7.8 W/m2 and 10.5 W/m2, respectively. The proposed method is especially applicable to acquire relatively high accurate DSLR under heavy dust aerosol using MODIS data with available WVC and AOD data. © 2017 by the authors."
"55747201700;56032594900;6507495053;6603423022;8669401600;6602577491;57203260074;6603180620;","The influence of synoptic circulations and local processes on temperature anomalies at three French observatories",2017,"10.1175/JAMC-D-16-0113.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009446833&doi=10.1175%2fJAMC-D-16-0113.1&partnerID=40&md5=ff0aa2885b0f4b4a8ca9fdb4b17d8d79","The relative contribution of the synoptic-scale circulations to local and mesoscale processes was quantified in terms of the variability of midlatitude temperature anomalies from 2003 to 2013 using meteorological variables collected from three French observatories and reanalyses. Four weather regimes were defined from sea level pressure anomalies using National Centers for Environmental Prediction reanalyses with a K-means algorithm. No correlation was found between daily temperature anomalies and weather regimes, and the variability of temperature anomalies within each regime was large. It was therefore not possible to evaluate the effect of large scales on temperature anomalies by this method. An alternative approach was found with the use of the analogs method: the principle being that for each day of the considered time series, a set of days that had a similar large-scale 500-hPa geopotential height field within a fixed domain was considered. The observed temperature anomalies were then compared with those observed during the analog days: the closer the two types of series are to each other, the greater is the influence of the large scale. This method highlights a widely predominant influence of the large-scale atmospheric circulation on the temperature anomalies. It showed a potentially larger influence of the Mediterranean Sea and orographic flow on the two southern observatories. Low-level cloud radiative effects substantially modulated the variability of the daily temperature anomalies."
"56300178700;55495868700;56278774300;50462946300;57062525000;56278523400;","3D aerosol climatology over East Asia derived from CALIOP observations",2017,"10.1016/j.atmosenv.2017.01.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008941099&doi=10.1016%2fj.atmosenv.2017.01.013&partnerID=40&md5=0409504d29134df88d11ec3874d1fccc","The seasonal mean extinction coefficient profile (ECP), single scattering albedo (SSA), and scattering phase function (SPF) derived from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) version 3 Level 2 5-km aerosol profile product (2011–2014) were compiled into a three-dimensional (3D) aerosol climatology for East Asia. The SSA and SPF were calculated as the weighted averages of the scattering properties of the CALIOP aerosol subtypes. The weights were set to the occurrence frequencies of the subtypes. The single scattering properties of each subtype were extrapolated from the volume-based size distribution and complex refractive indexes based on Mie calculations. For the high-loading episodes (aerosol optical depth ≥ 0.6), the exponential ECP structures were most frequently observed over the farmland and desert areas, along with the uplifted ECP structures over the marine and coastal areas. Besides the desert areas, high-loading episodes also occurred over areas with frequent agricultural and industry activities. Unlike the conventional half-3D aerosol climatology (vertically constant SSA and SPF), this newly generated climatology specified SSA and SPF in the full-3D space (full-3D aerosol climatology). Errors on the shortwave radiative heating rate (SW RHR) due to the half-3D aerosol climatology approximation were quantified. The SW RHR errors were around ±1 K/day, implying that the half-3D aerosol climatology should be used with caution in climate modeling. This study is among the first to generate a full-3D aerosol climatology from the CALIOP data. This full-3D aerosol climatology is potentially useful for aerosol remote sensing and climate modeling. © 2017 Elsevier Ltd"
"6602078681;55262499900;55621952600;","Angular effect of undetected clouds in infrared window radiance observations: Aircraft experimental analyses",2016,"10.1175/JAS-D-15-0262.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965147433&doi=10.1175%2fJAS-D-15-0262.1&partnerID=40&md5=ad09bb54307a38629473327587a2e42e","This paper furthers previous investigations into the zenith angular effect of cloud contamination within infrared (IR) window radiance observations commonly used in the retrieval of environmental data records (EDRs). Here analyses were performed of clear-sky forward radiance calculations versus observations obtained under clear to partly cloudy conditions over ocean. The authors utilized high-resolution IR spectra observed by the aircraft-based National Polar-Orbiting Partnership (NPP) Aircraft Sounder Test Bed-Interferometer (NAST-I) during the Joint Airborne Infrared Atmospheric Sounding Interferometer (IASI) Validation Experiment (JAIVEx) and performed forward calculations using collocated dropsondes. An aerosol optical depth EDR product derived from Geostationary Operational Environmental Satellite (GOES) was then applied to detect clouds within NAST-I fields of view (FOVs). To calculate the angular variation of clouds, expressions were derived for estimating cloud aspect ratios from visible imagery where cloud shadow lengths can be estimated relative to cloud horizontal diameters. In agreement with sensitivity calculations, it was found that a small cloud fraction within window radiance observations can have a measurable impact on the angular agreement with clear-sky calculations on the order of 0.1-0.4K in brightness temperature. It was also found that systematic sun-glint contamination can likewise have an impact on the order of 0.1 K. These results are germane to IR sensor data record (SDR) calibration/validation and EDR retrieval schemes depending upon clear-sky SDRs, as well as radiative transfer modeling involving randomly distributed broken cloud fields. © 2016 American Meteorological Society."
"56800676100;16244996700;57096629100;57204549544;","Influence of aerosols on atmospheric variables in the HARMONIE model",2016,"10.1016/j.atmosres.2015.08.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954398952&doi=10.1016%2fj.atmosres.2015.08.001&partnerID=40&md5=b33dd33f1752034d6cf85edd18fa5f0a","The mesoscale HARMONIE model is used to investigate the potential influence of aerosols on weather forecasts, and in particular, on precipitation. The study considers three numerical experiments over the Atlantic-Europe-Northern Africa region during 11-16 August 2010 with the following configurations: (a) no aerosols, (b) only the sea aerosols, and (c) the four types of the aerosols: sea, land, organic, and dust aerosols. The spatio-temporal analysis of forecast differences highlights the impact of aerosols on the prediction of main meteorological variables such as air temperature, humidity, precipitation, and cloud cover as well as their vertical profiles. The variations occur through changes in radiation fluxes and microphysics properties. The sensitivity experiments with the inclusion of climatological aerosol concentrations demonstrate the importance of aerosol effects on weather prediction. © 2015 Elsevier B.V."
"55796506900;55355176000;","Advances in studies of cloud overlap and its radiative transfer in climate models",2016,"10.1007/s13351-016-5164-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007241901&doi=10.1007%2fs13351-016-5164-5&partnerID=40&md5=4c1115c7a7458ff6c6035d1a3b0e573a","The latest advances in studies on the treatment of cloud overlap and its radiative transfer in global climate models are summarized. Developments with respect to this internationally challenging problem are described from aspects such as the design of cloud overlap assumptions, the realization of cloud overlap assumptions within climate models, and the data and methods used to obtain consistent observations of cloud overlap structure and radiative transfer in overlapping clouds. To date, there has been an appreciable level of achievement in studies on cloud overlap in climate models, demonstrated by the development of scientific assumptions (e.g., e-folding overlap) to describe cloud overlap, the invention and broad application of the fast radiative transfer method for overlapped clouds (Monte Carlo Independent Column Approximation), and the emergence of continuous 3D cloud satellite observation (e.g., CloudSat/CALIPSO) and cloud-resolving models, which provide numerous data valuable for the exact description of cloud overlap structure in climate models. However, present treatments of cloud overlap and its radiative transfer process are far from complete, and there remain many unsettled problems that need to be explored in the future. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2016."
"42261008800;55644747600;55578290900;56013128700;","Hourly global solar radiation estimation from MSG-SEVIRI images-case study: Algeria",2016,"10.1108/WJE-06-2016-036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992562828&doi=10.1108%2fWJE-06-2016-036&partnerID=40&md5=2aadf3ba73da930f966a8cebd72d1360","Purpose - This paper aims to propose an approach based on physical model integration for surface and cloud albedo computation using an approximate form of the atmospheric radiative transfer equation and sun-pixel-satellite. Design/methodology/approach - The data used in this study are global irradiance collected from for various sites in Algeria, and data were obtained from the processing of the high-resolution visible images taken by the Meteosat Second Generation satellite in 2010. Findings - The results suggest that the standard deviation obtained with this method is similar to that obtained with current estimation methods. The hourly and daily correlation coefficients range between 0.95 and 0.97 and between 0.97 and 0.99, respectively. The hourly and daily mean bias errors range between -0.2 and +1.2 per cent and between -0.2 and +1.4 per cent, respectively. The hourly and daily root mean square errors range between 10 and 17 per cent and between 4 and 8 per cent, respectively. Originality/value - This paper developed a new estimating method that derives the hourly global horizontal solar irradiation at a ground level from geostationary satellite data under local climate conditions. © 2016 Emerald Group Publishing Limited."
"56125661000;16230139500;16426140700;8380252900;36486362800;","Exploiting the sensitivity of two satellite cloud height retrievals to cloud vertical distribution",2015,"10.5194/amt-8-3419-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940209939&doi=10.5194%2famt-8-3419-2015&partnerID=40&md5=93279d17a727ff3abb5a6e3e89ab7c48","This work presents a study on the sensitivity of two satellite cloud height retrievals to cloud vertical distribution. The difference in sensitivity is exploited by relating the difference in the retrieved cloud heights to cloud vertical extent. The two cloud height retrievals, performed within the Freie Universität Berlin AATSR MERIS Cloud (FAME-C) algorithm, are based on independent measurements and different retrieval techniques. First, cloud-top temperature (CTT) is retrieved from Advanced Along Track Scanning Radiometer (AATSR) measurements in the thermal infrared. Second, cloud-top pressure (CTP) is retrieved from Medium Resolution Imaging Spectrometer (MERIS) measurements in the oxygen-A absorption band and a nearby window channel. Both CTT and CTP are converted to cloud-top height (CTH) using atmospheric profiles from a numerical weather prediction model. First, a sensitivity study using radiative transfer simulations in the near-infrared and thermal infrared was performed to demonstrate, in a quantitative manner, the larger impact of the assumed cloud vertical extinction profile, described in terms of shape and vertical extent, on MERIS than on AATSR top-of-atmosphere measurements. Consequently, cloud vertical extinction profiles will have a larger influence on the MERIS than on the AATSR cloud height retrievals for most cloud types. Second, the difference in retrieved CTH (ΔCTH) from AATSR and MERIS are related to cloud vertical extent (CVE), as observed by ground-based lidar and radar at three ARM sites. To increase the impact of the cloud vertical extinction profile on the MERIS-CTP retrievals, single-layer and geometrically thin clouds are assumed in the forward model. Similarly to previous findings, the MERIS-CTP retrievals appear to be close to pressure levels in the middle of the cloud. Assuming a linear relationship, the ΔCTH multiplied by 2.5 gives an estimate on the CVE for single-layer clouds. The relationship is stronger for single-layer clouds than for multi-layer clouds. Due to large variations of cloud vertical extinction profiles occurring in nature, a quantitative estimate of the cloud vertical extent is accompanied with large uncertainties. Yet, estimates of the CVE provide an additional parameter, next to CTH, that can be obtained from passive imager measurements and can be used to further describe cloud vertical distribution, thus contributing to the characterization of a cloudy scene. To further demonstrate the plausibility of the approach, an estimate of the CVE was applied to a case study. In light of the follow-up mission Sentinel-3 with AATSR and MERIS like instruments, Sea and Land Surface Temperature Radiometer (SLSTR) and (Ocean and Land Colour Instrument) OLCI, respectively, for which the FAME-C algorithm can be easily adapted, a more accurate estimate of the CVE can be expected. OLCI will have three channels in the oxygen-A absorption band, possibly providing enhanced information on cloud vertical distributions. © Author(s) 2015."
"56100422000;7102866124;6603497730;","Inner convective system cloud-top wind estimation using multichannel infrared satellite images",2014,"10.1080/01431161.2013.871391","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84892986516&doi=10.1080%2f01431161.2013.871391&partnerID=40&md5=21537a7125dee76663f43eb3d1c84754","Knowledge of deep convective system cloud processes and dynamic structures is a key feature in climate change and nowcasting. However, the horizontal inner structures at the cloud tops of deep convective systems are not well understood due to lack of measurements and the complex processes linked to dynamics and thermodynamics. This study describes a new technique to extract inner cloud-top dynamics using brightness temperature differences. This new information could help clarify ring and U or V shape structures in deep convection and be potentially useful in nowcasting applications. Indeed, the use of high-resolution numerical weather prediction (NWP) models, which now include explicit microphysical processes, requires data assimilation at very high resolution as well. A standard atmospheric motion vector tracking algorithm was applied to a pair of images composed of combinations of Spinning Enhanced Visible and Infra-red Imager (SEVIRI) channels. Several ranges of channel differences were used in the tracking process, such intervals being expected to correspond to specific cloud-top microphysics structures. Various consistent flows of motion vectors with different speeds and/or directions were extracted at the same location depending on the channel difference intervals used. These differences in speed/direction can illustrate local wind shear situations, or correspond to expansion or dissipation of cloud regions that contain high concentrations of specific kinds of ice crystals or droplets. The results from this technique were compared to models and ancillary data to advance our discussion and inter-comparisons. Also, the technique proposed here was evaluated using SEVIRI images simulated by the radiative transfer model RTTOV with input data from the UK Met Office Unified Model. A future application of the new data is exemplified by showing the relationship between wind divergence calculated from the new atmospheric motion vector and convective cloud top intensification. © 2014 © Taylor & Francis."
"7801344746;55339298600;57206531303;16639418500;","HelioFTH: Combining cloud index principles and aggregated rating for cloud masking using infrared observations from geostationary satellites",2013,"10.5194/amt-6-1883-2013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882378249&doi=10.5194%2famt-6-1883-2013&partnerID=40&md5=38bdc95b10cb99f762a60620279b13b9","In this paper a cloud mask and cloud fractional coverage (CFC) retrieval scheme called HelioFTH is presented. The algorithm is self-calibrating and relies on infrared (IR) window-channel observations only. It needs no input from numerical weather prediction (NWP) or radiative transfer models, nor from other satellite platforms. The scheme is applicable to the full temporal and spatial resolution of the Meteosat Visible and InfraRed Imager (MVIRI) and the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensors. The main focus is laid on the separation of middle- and high-level cloud coverage (HCC) from low-level clouds based on an internal cloud-top pressure (CTP) product. CFC retrieval employs a IR-only cloud mask based on an aggregated rating scheme. CTP retrieval is based on a Heliosat-like cloud index for the MVIRI IR channel. CFC from HelioFTH, the International Satellite Cloud Climatology Project (ISCCP) DX and the Satellite Application Facility on Climate Monitoring (CM SAF) were validated with CFC from the Baseline Surface Radiation Network (BSRN) and the Alpine Surface Radiation Budget (ASRB) network. HelioFTH CFC differs by not more than 5-10% from CM SAF CFC but it is higher than ISCCP-DX CFC. In particular the conditional probability to detect cloud-free pixels with HelioFTH is raised by about 35% compared to ISCCP-DX. The HelioFTH CFC is able to reproduce the day-to-day variability observed at the surface. Also, the HelioFTH HCC was inter-compared to CM SAF and ISCCP-DX over different regions and stations. The probability of false detection of cloud-free HCC pixels is in the same order as ISCCP-DX compared to the CM SAF HCC product over the full-disk area. HelioFTH could be used for generating an independent climate data record of cloud physical properties once its consistency and homogeneity is validated for the full Meteosat time series. © Author(s) 2013."
"55332186500;7102290666;6506966551;","Effects of additional particles on already polluted marine stratus",2012,"10.1175/JAS-D-11-0291.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84864839464&doi=10.1175%2fJAS-D-11-0291.1&partnerID=40&md5=50d564bd935fd52b12f625de0939064b","The response of already polluted marine stratocumulus to additional particles was examined by studying the clouds where two ship tracks cross. Nearly 100 such crossings were collected and analyzed using Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) multispectral imagery for the daytime passes off the western coast of the United States during the summer months of 4 years. To reduce biases in the retrieved cloud properties caused by the subpixel spatial structure of the clouds, results are presented only for ship tracks found in regions overcast by extensive layers of marine stratus. When two ship tracks cross, one of the tracks exhibits much larger changes in droplet radii when compared with the surrounding unpolluted clouds and is referred to as the dominant ship track. The clouds at the crossing typically exhibit properties that are closer to those of the dominant than to those of the subordinate ship track. To determine whether the additional particles at the crossing affect the dominant track, local gradients in the retrieved cloud properties near the crossing were determined for both ship tracks. Based on the gradients, the clouds at the junction were found to have significantly smaller droplet radii and significantly larger column droplet number concentrations than were predicted based on their values in both ship tracks on either side of the crossing. Comparing the effects of particle loading at the crossings and elsewhere along the ship tracks revealed that the effects decreased as the column droplet number concentration of the clouds being affected increased. © 2012 American Meteorological Society."
"6603968694;6701689811;","Ganges valley aerosol experiment",2011,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-80053510167&partnerID=40&md5=c9dd004b3736aaaaa130a678a7a2d729","The US Department of Energy (DOE), in collaboration with the Indian Space Research Organization and the Indian Institute of Science, is conducting a large-scale field study, the Ganges Valley Aerosol Experiment, to study the effects of aerosols and associated pollution on solar input to the surface and on monsoon rainfall. During the experiment field studies, aerosols from the Ganges Valley were shown to affect cloud formation and monsoon activity over the Indian Ocean. The primary anchor facility for the project is the mobile climate monitoring facility AMF-1, offering an opportunity to study the prevailing patterns of cloud, convective mixing, and aerosol loads that are representative of the Indian subcontinent. The diurnal variability in aerosol, amounting to 50% and more, provides a unique opportunity to estimate the direct radiative forcing impact of aerosols on radiative transfer."
"14064156500;7004144610;","Radiative transfer simulations for the MADRAS imager of Megha-Tropiques",2011,"10.1007/s12040-011-0012-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052669247&doi=10.1007%2fs12040-011-0012-6&partnerID=40&md5=d7df2000f6376bfbd9a1d707fd10ddf2","This paper reports the radiative transfer simulations for the passive microwave radiometer onboard the proposed Indian climate research satellite Megha-Tropiques due to be launched in 2011. These simulations have been performed by employing an in-house polarized radiative transfer code for raining systems ranging from depression and tropical cyclones to the Indian monsoon. For the sake of validation and completeness, simulations have also been done for the Tropical Rainfall Measuring Mission (TRMM)'s Microwave Imager (TMI) of the highly successful TRMM mission of NASA and JAXA. The paper is essentially divided into two parts: (a) Radiometer response with specific focus on high frequency channels in both the radiometers is discussed in detail with a parametric study of the effect of four hydrometeors (cloud liquid water, cloud ice, precipitating water and precipitating ice) on the brightness temperatures. The results are compared with TMI measurements wherever possible. (b) Development of a neural network-based fast radiative transfer model is elucidated here. The goal is to speed up the computational time involved in the simulation of brightness temperatures, necessitated by the need for quick and online retrieval strategies. The neural network model uses hydrometeor profiles as inputs and simulates spectral microwave brightness temperature at multiple frequencies as output. A huge database is generated by executing the in-house radiative transfer code for seven different cyclones occurred in North Indian Ocean region during the period 2001-2006. A part of the dataset is used to train the network while the remainder is used for testing purposes. For the purpose of testing, a typical scene from the southwest monsoon rain is also considered. The results obtained are very encouraging and show that the neural network is able to mimic the underlying physics of the radiative transfer simulations with a correlation coefficient of over 99%. © Indian Academy of Sciences."
"7202970886;57190749913;","Employing cluster analysis to detect significant cloud 3D RT effect indicators",2010,"10.1175/2010JAS3414.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955565715&doi=10.1175%2f2010JAS3414.1&partnerID=40&md5=cdcfa1daf7bee054131c0f36b2992313","Three-dimensional cloud field morphology contributes to scene-averaged cloud reflectivity, but climate models do not currently incorporate methods of identifying situations where this contribution is substantial. This work represents an effort to identify atmospheric conditions conducive to the formation of cloud field configurations that significantly affect shortwave radiative fluxes. Once identified, these characteristics may form the basis of a parameterization that accounts for radiative impact of complex cloud fields. A k-means clustering algorithm is applied to observed cloud properties taken from the Atmospheric Radiation Measurement Program tropical western Pacific sites to identify specific cloud regimes. Results from a stand-alone stochastic model, which statistically represents shortwave radiative transfer through broken cloud fields, are compared with those of a plane-parallel model. The aggregate scenes in each regime are examined to measure the bias in shortwave flux calculations due to neglected cloud field morphology. The results from the model comparison and cluster analysis suggest that cloud fraction, vertical wind shear, and spacing between cloudy layers are all important indicators of complex cloud field geometry and that these criteria are most often met in cloud regimes characterized by moderate to strong convection. The cluster criteria are applied to output from the Community Climate System Model (version 3.0) and it is found that the presence of persistent high cirrus cloud in model simulations inhibits identification of specific cloud regimes. © 2010 American Meteorological Society."
"16426140700;8380252900;7404369915;","Remote sensing of multilayer cloud-top pressure using combined measurements of MERIS and AATSR on board Envisat",2010,"10.1175/2010JAMC2331.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955546226&doi=10.1175%2f2010JAMC2331.1&partnerID=40&md5=88093051a7c01811badd146211e97778","A novel and unique algorithm for the retrieval of multilayer cloud-top pressure is presented, relying on synergetic observations of the Medium Resolution Imaging Spectrometer (MERIS) and Advanced Along Track Scanning Radiometer (AATSR) on board the Environmental Satellite (Envisat). The retrieval is based on the exploitation of the differing signals observed in the thermal infrared spectral region (AATSR) and the oxygen A band at 0.76 μm (MERIS). Past studies have shown that the cloud-top pressure retrieved from MERIS measurements is highly accurate in the case of low single-layered clouds. In contrast, in the presence of multilayered clouds like cirrus overlying water clouds, the derived cloud height is biased. In this framework, an optimal estimation algorithm for the correction of the measured O2 A transmission for the influence of the upper cloud layer was developed. The algorithm is best applicable in cases of optically thin cirrus (1 ≤ τ ≤ 5) above optically thick water clouds (τ > 5), as found frequently in the vicinity of convective or frontal cloud systems. The split-window brightness temperature difference technique is used for the identification of suitable cases. The sensitivities of the AATSR and MERIS measurements to multilayered clouds are presented and discussed, revealing that in the case of dual-layered clouds, the AATSR-derived cloud height is close to the upper cloud layer, even if it is optically thin. In contrast, the cloud height retrieved from MERIS measurements represents the optical center of the cloud system, which is close to the lower layer in cases where the upper layer is optically thin. Two case studies of convective, multilayered cloud systems above the northern Atlantic Ocean are shown, demonstrating the plausibility of the approach. The presented work is relevant especially in view of the upcoming Global Monitoring for Environment and Security Sentinel-3 satellite to be launched in 2012 that will carry the respective MERIS and AATSR follow-up instruments Ocean and Land Colour Instrument (OLCI) and Sea and Land Surface Temperature Radiometer (SLSTR). © 2010 American Meteorological Society."
"57201725986;7102543399;","Effects of sea surface temperature, radiation, cloud microphysics, and diurnal variations on vertical structures of tropical tropospheric temperature: A two-dimensional equilibrium cloud-resolving modeling study",2009,"10.1007/s00703-009-0039-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-69949128601&doi=10.1007%2fs00703-009-0039-2&partnerID=40&md5=219b342eaee3268dbba6c929f2ddfbbf","The effects of sea surface temperature (SST), radiation, cloud microphysics, and diurnal variations on the vertical structure of tropical tropospheric temperature are investigated by analyzing 10 two-dimensional equilibrium cloud-resolving model simulation data. The increase of SST, exclusion of diurnal variation of SST, and inclusion of diurnal variation of solar zenith angle, radiative effects of ice clouds, and ice microphysics could lead to tropical tropospheric warming and increase of tropopause height. The increase of SST and the suppression of its diurnal variation enhance the warming in the lower and upper troposphere, respectively, through increasing latent heat and decreasing IR cooling. The inclusion of diurnal variation of solar zenith angle increases the tropospheric warming through increasing solar heating. The inclusion of cloud radiative effects increases tropospheric warming through suppressing IR cooling in the mid and lower troposphere and enhancing solar heating in the upper troposphere. The inclusion of ice microphysics barely increases warming in the mid and lower troposphere because the warming from ice radiative effects is nearly offset by the cooling from ice microphysical effects, whereas it causes the large warming enhancement in the upper troposphere due to the dominance of ice radiative effects. The tropopause height is increased mainly through the large enhancement of IR cooling. © Springer-Verlag 2009."
"13406722400;7402451396;","Cloud-radiative impacts on the tropical Indian Ocean associated with the evolution of 'monsoon breaks'",2008,"10.1002/joc.1518","https://www.scopus.com/inward/record.uri?eid=2-s2.0-39549084935&doi=10.1002%2fjoc.1518&partnerID=40&md5=88f1f5f6e2ee779a8a8cb2e3213732de","A detailed diagnostic analysis of a suite of observed datasets was carried out with a view to understand the importance of cloud-radiative effects on the evolution of prolonged 'monsoon breaks' over the Indian region. The study particularly focuses on the role of clouds in affecting the sub-seasonal/intra-seasonal variability of sea surface temperature (SST) and atmospheric convection in the equatorial and south-eastern tropical Indian Ocean (SETIO) during monsoon-break transitions. A characteristic feature of the monsoon-break evolution is the appearance of suppressed convection over the SETIO region nearly 7-10 days prior to the commencement of a break spell over India. It is seen from the present analysis that the lack of cloud cover over the SETIO during the 'pre-break' phase leads to significant warming of the tropical Indian Ocean due to strong solar insolation at the surface. During the 'pre-break' phase, the net cloud-radiative forcing (NETCRF) at the surface is found to be typically around -30 Wm-2 and the mean SST in the SETIO is about 29.3°C. Following the transition to a monsoon-break phase, the cloud amount increases by about 25% over the SETIO region in association with intensified convection. The NETCRF at the surface over the SETIO averaged during the 'break' phase is found to be about -60 Wm-2 (i.e. a change of about -30 Wm-2 from the 'pre-break' phase). Consistent with the above change in the NETCRF, the SST in the SETIO shows a cooling of about 0.7°C, although the mean SSTs during the 'break' phase remain as high as 28.6°C. On the basis of the findings from this study, it is suggested that the SST warming during the 'pre-break' phase plays a key role in maintaining high SST and allows sustained convection to occur over the SETTO during prolonged monsoon breaks. Copyright © 2007 Royal Meteorological Society."
"8891521600;7402727711;7006147398;57198579670;","Outgoing longwave radiation and cloud radiative forcing of the Tibetan Plateau",2000,"10.1029/2000JD900201","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033785630&doi=10.1029%2f2000JD900201&partnerID=40&md5=c2b1ebb54d01d95146c3c3cf93fa8c0a","In order to study the energy balance and the cloud radiative forcing (CRF) of the Tibetan Plateau in detail, 2 years of GMS5 satellite data are employed to analyze the monthly mean outgoing longwave radiation (OLR) and CRF. It should be noted that the temporal resolution of GMS5 data is 1 hour, so the data can be used to study the diurnal variations of OLR. First, a method is presented to retrieve the OLR from split-window channels (10.5-11.5 and 11.5-12.5 μm) and the water vapor channel (6.5-7.0 μm) of GMS5. The method applies the discrete ordinates radiative transfer (DISORT) model together with the radiosonde profiles of the Tibetan Plateau to simulate radiances and fluxes of the three channels. A regression relationship is then developed to calculate the OLR from the observations of the three channels. Since the Tibetan Plateau is located nearly out of the effective observational range of the GMS5 satellite, the regression results of GMS5's split-window channels and water vapor channel are corrected by using simultaneously retrieved results from TIROS Operational Vertical Sounder (TOVS). The correlation coefficient of GMS5 and TOVS results is 0.8510, which is large enough for 1% significant level. The OLR distributions arc calculated for the Tibetan Plateau using 2 years of GMS5 data and the regression and correction methods. The average of the OLR images for the same month and same time gives the monthly mean OLR distribution for each hour. The 24-hour OLR distributions of the same month are then averaged to yield the monthly mean OLR distribution for that month. Then our monthly mean OLR distributions are compared with the Clouds and the Earth's Radiant Energy System (CERES) results, and they are generally in good agreement with differences of <10% for January and 5% for July. Analyzing the monthly mean OLR distributions for different seasons, we find that during the winter season the OLR distribution exhibits low values over the Tibetan Plateau but high values for areas off the Tibetan Plateau. During the summer season the OLR of the southern part is smaller than that of the northern part. Studying the monthly mean diurnal variations of OLR, we find that the diurnal variations of OLR are affected by diurnal cycles of cloud quantity and surface temperature. The relief of the Tibetan Plateau is very high, and the radiative heating is intense after sunrise. The OLR is greatly influenced by the surface and reaches a maximum value soon after sunrise, but the time the minimum OLR emerges varies. After the OLR distributions of the Tibetan Plateau are obtained, the role of clouds in the climate system is also studied. In order to calculate the CRF the International Satellite Cloud Climatology Project (ISCCP) cloud detection algorithm is used to detect the clear pixels for each image. The clear-sky components of OLR and albedo for different months and hours are then derived and averaged over a month to obtain the monthly mean clear-sky OLR and albedo for each hour. Finally, data are averaged over 24 hours to give the monthly mean shortwave CRF (SWCRF), longwave CRF (LWCRF), and CRF. The results show that the CRF over the Tibetan Plateau is negative most of the time. This means the CRF is dominated by cooling effects, and the distribution pattern is mainly determined by the SWCRF component. While the CRFs to the south and the north of the Tibetan Plateau are different, there are obvious annual variations with heating effects in the summer-autumn season and cooling effects in the winter-spring season. Copyright 2000 by the American Geophysical Union."
"7201653018;7201483914;","Role of radiative transfer in maintenance and destruction of stratocumulus clouds",1995,"10.1016/1352-2310(94)00242-D","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028991265&doi=10.1016%2f1352-2310%2894%2900242-D&partnerID=40&md5=dd6dc2f3b83c7485a5732e02d87f360d","A mesoscale numerical model is used to study the physical processes in the maintenance of a stratocumulus topped boundary layer. The model includes a surface energy budget, closure using a scheme based on the turbulence kinetic energy, a five category cloud physics scheme and radiative transfer. Model results demonstrate the role radiative flux divergence plays in the maintenance of a stratocumulus layer. Radiative heating and cooling of the cloud layer destabilizes the upper boundary layer and decouples that portion of the boundary layer from the surface layer. Eventually, sufficient solar radiation reaches the surface to overcome the decoupling and the cloud layer dissipates. © 1995."
"6602087295;6506581660;57198655623;","Rice production and climate change: design and development of a GIS database to complement simulation models",1993,"10.1007/BF00141588","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042469847&doi=10.1007%2fBF00141588&partnerID=40&md5=a1fbc91a679713717207c14424df3cc4","A cooperative project between the International Rice Research Institute in Los Baños, Philippines, and the U.S. EPA Environmental Research Laboratory in Corvallis, Oregon, was initiated to estimate how rice yield in Asia might be affected by future climate change and enhanced UV-B irradiance following stratospheric ozone depletion. A radiative transfer model was used to estimate daily UV-B irradiance levels using remotely sensed ozone and cloud cover data for 1274 meteorological stations. A rice yield model using daily climatic data and cultivar-specific coefficients was used to predict changes in yield under given climate change scenarios. This paper gives an overview of the data required to run these two models and describes how a geographical information system (GIS) was used as a data pre- or postprocessor. Problems in finding reliable datasets such as cloud cover data needed for the UV-B radiation model and radiation data needed for the rice yield model are discussed. Issues of spatial and temporal scales are also addressed. Using simulation models at large spatial scales helped identify weaknesses of GIS data overlay and interpolation capabilities. Even though we focussed our efforts on paddy rice, the database is not intended to be system specific and could also be used to analyze the response of other natural systems to climatic change. © 1993 SPB Academic Publishing bv."
"7401491382;7403233451;","The climatological minimum in tropical outgoing infrared radiation: Contributions of humidity and clouds",1983,"10.1002/qj.49710945908","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021050799&doi=10.1002%2fqj.49710945908&partnerID=40&md5=a2379e9df7e0e85fbc6dfdfef6e672cd","Satellite observations of outgoing terrestrial infrared (IR) radiation as a function of latitude exhibit a minimum near the equator 20–40 Wm−2 smaller than peaks in the subtropics. We attempt to dissect the causes of the dip through calculations with a spectrally‐detailed multi‐level radiative transfer model. Roughly one third of the dip can be attributed to the latitudinal variation of atmospheric water vapour; the remainder apparently is due to latitudinal variations in cloud amount and (especially) cloud‐top height. However, inclusion of clouds as given by published climatologies enhances the clear‐sky dip only slightly. Thus, about one half of the dip is essentially unexplained. We suspect the explanation is that near‐equatorial cirrus and cumulonimbus heights are too low in the cloud climatology, emphasizing the need for a better cloud climatology. Since tropospheric humidity variations have a strong effect on clear‐sky outgoing IR, empirical studies which correlate cloud with IR variations may overestimate the effect of clouds on outgoing IR if cloud amount is correlated with relative humidity. The effect of humidity variations on outgoing IR suggests that a measure of tropospheric humidity be incorporated explicitly in the parametrization of outgoing IR for simple climate models. Copyright © 1983 Royal Meteorological Society"
"7401904068;","Atmospheric particles and climate: can we evaluate the impact of man's activities?",1972,"10.1016/0033-5894(72)90068-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-29144474664&doi=10.1016%2f0033-5894%2872%2990068-3&partnerID=40&md5=9defd58ef43b62c6e4b7425b60e9eb5d","The equilibrium temperature of the Earth is maintained by a balance between the unreflected part of the incoming solar energy, which is absorbed by the Earth-atmosphere system, and the outgoing long-wave radiation escaping from the Earth to space. It has long been suspected that suspended atmospheric particles (aerosols) might affect this balance, primarily by affecting the albedo or reflectivity of the Earth, thereby altering the amount of solar energy absorbed by the Earth. In light of some recent evidence suggesting the existence of an increase in atmospheric particle concentrations (presumably related to man's activities), the need for development of adequate numerical models to study this problem is apparent. Recent numerical models studying the effect of particles on climate are often based on multiple scattering radiative transfer calculations, and use global averages for particle concentrations and optical properties. By contrasting certain existing models, some major problems in modeling studies that attempt to answer the question of the effects of increased atmospheric particles on climate can be illustrated. It will also be apparent that another uncertainty in the results of such studies arises from a lack of adequate observed input data on the geographic and vertical distributions of particle concentrations and their optical properties. Furthermore, a model that could realistically simulate the impact of increasing atmospheric particle concentration on climate must eventually include the simultaneous coupled effects of all the important atmospheric processes, such as fluid motions and cloud microphysics, in addition to the radiative transfer effects. Current modeling studies already do predict that increases in particle concentrations could have a significant effect on climate. Now, it remains for us to develop the kinds of refined models needed to verify or deny these predictions. © 1972."
"57204072572;36145802300;56058138700;35488600800;55262835400;56585621300;57208800761;55470933800;","Black Carbon aerosol characteristics and radiative forcing over the high altitude glacier region of Himalaya-Karakorum-Hindukush",2020,"10.1016/j.atmosenv.2020.117711","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087478643&doi=10.1016%2fj.atmosenv.2020.117711&partnerID=40&md5=741d5daf7de8b285b7373a0ac7745004","Absorbing aerosols mainly Black Carbon (BC) have potential effects on the hydrological cycle and climate change over the high-altitude regions particularly in South Asia. The BC measurements are sparse in high altitude locations of the world particularly over the Northern regions of Pakistan. This study investigated the diurnal/monthly variations of BC and its climatic impacts during the period of 2016–2017 over four high altitude locations, i.e., Astore, Gilgit, Sost and Skardu located in the Himalaya-Karakorum-Hindukush (HKH) mountain ranges in Northern Pakistan. The Optical Properties of Aerosols and Clouds (OPAC) model was used for the estimation of aerosol optical properties, e.g., Aerosol Optical Depth (AOD), Asymmetry Parameter (AP) and Single Scattering Albedo (SSA) using the BC number density corresponding to the BC mass concentration. Then the model derived optical properties (AOD, AP and SSA), surface reflectance, ozone and water vapor were used in Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model for the calculation of BC aerosol radiative forcing (ARF) at the Top Of Atmosphere (TOA), Surface (SUR) and within the ATMosphere (ATM). The results revealed that the mean monthly BC concentrations were maximum during November (3.05 ± 0.7 μg/m3) as well as in December (3.05 ± 0.5 μg/m3) at Gilgit and minimum during August (1.1 ± 0.3 μg/m3) at Sost. Correspondingly, the diurnal variation of BC concentrations displayed strong fluctuations, with high concentrations in the late night and early morning during November and December for Astore and Gilgit, respectively. Generally, the BC concentrations were maximum/minimum in the morning/evening during May, June, August and September at all locations. The correlation of BC with different meteorological parameters showed that the BC has positive correlation with temperature and wind speed, while negative with relative humidity and rainfall. The HYSPLIT back trajectory analysis revealed that air masses arrived the study locations from both long distance (Turkmenistan, Tajikistan, Uzbekistan, Iran, Afghanistan, India, and China) and local sources. The monthly mean maximum and minimum BC ARF values at SUR (TOA) were found to be −43.7 ± 3.0 W/m2 (−8.2 ± 0.2 W/m2) and −16.4 ± 1.0 W/m2 (−1.2 ± 0.1 W/m2), respectively, giving an averaged atmospheric forcing of 35.7 ± 2.3 W/m2 and 15.2 ± 1.9 W/m2. © 2020 Elsevier Ltd"
"57211041878;55706370400;8983875000;14051882200;35237179700;","Detectability of Molecular Signatures on TRAPPIST-1e through Transmission Spectroscopy Simulated for Future Space-based Observatories",2020,"10.3847/2041-8213/aba4a1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091694418&doi=10.3847%2f2041-8213%2faba4a1&partnerID=40&md5=1eb8fd1b50b549e306ec5722f5bf20bc","Discoveries of terrestrial, Earth-sized exoplanets that lie within the habitable zone (HZ) of their host stars continue to occur at increasing rates. Transit spectroscopy can potentially enable the detection of molecular signatures from such worlds, providing an indication of the presence of an atmosphere and its chemical composition, including gases potentially indicative of a biosphere. Such planets around nearby M-dwarf stars - such as TRAPPIST-1 - provide a relatively good signal, high signal-to-noise ratio, and frequent transits for follow-up spectroscopy. However, even with these advantages, transit spectroscopy of terrestrial planets in the HZ of nearby M-stars will still be a challenge. Herein, we examine the potential for future space observatories to conduct such observations, using a global climate model, a photochemical model, and a radiative transfer suite to simulate modern-Earth-like atmospheric boundary conditions on TRAPPIST-1e. The detectability of biosignatures on such an atmosphere via transmission spectroscopy is modeled for various instruments of the James Webb Space Telescope, Large UV/Optical/Infrared Surveyor, Habitable Exoplanet Observatory, and Origins. We show that only CO2 at 4.3 μm would be detectable at the >5σ level in transmission spectroscopy, when clouds are included in our simulations. This is because the impact of clouds on scale height strongly limits the detectability of molecules in the atmosphere. Synergies between space- and ground-based spectroscopy may be essential in order to overcome these difficulties. © 2020. The American Astronomical Society. All rights reserved.."
"55802221900;23478660100;26031912400;57205842560;6506553245;6506416572;10339477400;57207941357;36187387300;23012746800;","Modulation of radiative aerosols effects by atmospheric circulation over the Euro-Mediterranean region",2020,"10.5194/acp-20-8315-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088588979&doi=10.5194%2facp-20-8315-2020&partnerID=40&md5=5f6822e586bddb6ff0d3bccb4751e194","The present work aims at better understanding regional climate-aerosol interactions by studying the relationships between aerosols and synoptic atmospheric circulation over the Euro-Mediterranean region. Two 40-year simulations (1979-2018) have been carried out with version 6.3 of the Centre National de Recherches Meteorologiques (National Centre for Meteorological Research)-Aire Limiteé Adaptation dynamique Développement InterNational (CNRM-ALADIN) regional climate model, one using interactive aerosols and the other one without any aerosol. The simulation with aerosols has been evaluated in terms of different climate and aerosol parameters. This evaluation shows a good agreement between the model and observations, significant improvements compared to the previous model version and consequently the relevance of using this model for the study of climate-aerosol interactions over this region. A first attempt to explain the climate variability of aerosols is based on the use of the North Atlantic Oscillation (NAO) index. The latter explains a significant part of the interannual variability, notably in winter for the export of dust aerosols over the Atlantic Ocean and the eastern Mediterranean, and in summer for the positive anomalies of anthropogenic aerosols over western Europe. This index is however not sufficient to fully understand the variations of aerosols in this region, notably at daily scale. The use of ""weather regimes"", namely persisting meteorological patterns, stable at synoptic scale for a few days, provides a relevant description of atmospheric circulation, which drives the emission, transport and deposition of aerosols. The four weather regimes usually defined in this area in winter and in summer bring significant information to answer this question. The blocking and NAOC regimes are largely favourable to strong aerosol effects on shortwave surface radiation and near-surface temperature, either because of higher aerosol loads or because of weaker cloud fraction, which reinforces the direct aerosol effect. Inversely, the NAO.. and Atlantic Ridge regimes are unfavourable to aerosol radiative effects, because of weaker aerosol concentrations and increased cloud cover. This study thus puts forward the strong dependence of aerosol loads on the synoptic circulation from interannual to daily scales and, as a consequence, the important modulation of the aerosol effects on shortwave surface radiation and near-surface temperature by atmospheric circulation. The role of cloud cover is essential in this modulation as shown by the use of weather regimes. © 2020 Author(s)."
"7403282069;57195591631;8977001000;7407116104;","Changes in clouds and atmospheric circulation associated with rapid adjustment induced by increased atmospheric CO2: a multiscale modeling framework study",2020,"10.1007/s00382-018-4401-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052296373&doi=10.1007%2fs00382-018-4401-2&partnerID=40&md5=e3955044695c1345abec24c43cafccb9","The radiative heating increase due to increased CO2 concentration is the primary source for the rapid adjustment of atmospheric circulation and clouds. In this study, we investigate the rapid adjustment resulting from an instantaneous doubling of CO2 and its physical mechanism using a multiscale modeling framework (MMF). The cloud-resolving model component of this MMF includes a sophisticated third-order turbulence closure and the MMF simulates realistic shallow and deep cloud climatology and boundary layer turbulence. Although the simulated cloud adjustment and its mechanism generally agree with earlier studies with conventional global climate models and another MMF with a lower-order turbulence closure, this MMF simulates an increase in the global-mean shortwave and net cloud radiative cooling and a negative cloud radiative effect change due to cloud adjustment. This result is related to the large increase in low-level clouds over the extratropical and subtropical oceans, resulting from reduced cloud-top entrainment implied from strengthened inversion. The downshift of planetary boundary layer and low-level clouds is generally weaker than that simulated by other models, which is due to reduction of shallow cumulus in the ascending and weak subsidence circulation regimes but to increase of stratocumulus in the strongest subsidence regime. Optically thicker stratocumulus compensates for reduced cooling by shallow cumulus. The reduced strength of all oceanic circulation regimes, which may be contributed by weakened energy transport resulting from water vapor and cloud CO2 masking effects, not only reduces optical depth of convective clouds but also shifts cloud coverage to lands where deep convection is enhanced. © 2018, The Author(s)."
"36706881700;56195639700;7409080503;57218665389;57138743300;","A 17-year climatology of temperature inversions above clouds over the ARM SGP site: The roles of cloud radiative effects",2020,"10.1016/j.atmosres.2019.104810","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077731831&doi=10.1016%2fj.atmosres.2019.104810&partnerID=40&md5=ab0f1c325d32787738bd231fefefc71d","Atmospheric temperature inversions, i.e., temperatures increasing with altitude, modulate both radiative and buoyancy fluxes in the atmosphere. A temperature inversion layer often occurs immediately above a cloud layer that cools radiatively and thereby strengthens the capping temperature inversion. This study aims to investigate the characteristics of temperature inversions above clouds and their relationships with cloud-top radiative cooling. Using a 17-year (January 2001 to December 2017) high-quality and continuous radiosonde dataset collected at the Atmospheric Radiation Measurement Southern Great Plains Central Facility site, key temperature inversion parameters, namely, the occurrence frequency (dp), depth (dz), temperature difference (dT), and gradient (dT/dz), are derived for single- and double-layer clouds (SLC and DLC, respectively). The occurrence frequency of temperature inversions above single-layer clouds decreases dramatically as cloud tops rise from low to high altitudes. When an overlying higher cloud layer is present, the inversion becomes less frequent, shallower, and weaker than without it. This may be because higher clouds weaken the cloud-top radiative cooling of the underneath clouds by enhancing downwelling infrared radiation. This is supported by radiative transfer simulations. There are distinctive seasonal cycles of cloud-top radiative cooling for high clouds that are primarily driven by variations in shortwave heating. Distinctive seasonal cycles of temperature inversions also occurred regardless of the cloud regime (SLC or DLC) and altitude (low or high clouds). They appear to be driven by the seasonal cycle of cloud coverage (i.e., a greater amount of clouds undergoes stronger area-mean radiative cooling) although the shortwave heating seasonal cycle also plays a role for high clouds. Cloud radiative cooling cannot explain the diurnal cycle of temperature inversions. © 2019 Elsevier B.V."
"57200926820;57216842449;","The incredible lightness of water vapor",2020,"10.1175/JCLI-D-19-0260.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084940411&doi=10.1175%2fJCLI-D-19-0260.1&partnerID=40&md5=a9b352b07a43895bc890fe06832ade96","The molar mass of water vapor is much less than that of dry air. This makes a moist parcel lighter than a dry parcel of the same temperature and pressure. This effect is referred to as the vapor buoyancy effect and has often been overlooked in climate studies. We propose that the vapor buoyancy effect increases Earth's outgoing longwave radiation (OLR) and that this negative radiative effect increases with warming, stabilizing Earth's climate. We illustrate this mechanism in an idealized tropical atmosphere, where there is no horizontal buoyancy gradient in the free troposphere. Temperature increases toward dry atmosphere columns to compensate the reduced vapor buoyancy, increasing OLR by O(1 W m22) at the reference climate. In warmer climates, the temperature difference between moist and dry columns would increase as a result of increasing atmospheric water vapor, leading to enhanced radiative effect and thereby stabilizing Earth's climate. We estimate that this feedback strength is about O(0.2 W m22 K21) in the idealized atmosphere, which compares to cloud feedback and surface albedo feedback in the current climate. We further show evidence from observations and real-gas radiative transfer calculations for a significant radiative effect of vapor buoyancy in the tropical atmosphere. © 2020 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses)."
"57200702127;56537463000;7404829395;56888217500;7005973015;","Impact of Cloud Ice Particle Size Uncertainty in a Climate Model and Implications for Future Satellite Missions",2020,"10.1029/2019JD032119","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082341001&doi=10.1029%2f2019JD032119&partnerID=40&md5=aca95b783374c7bbe3664b88b25a8cce","Ice particle size is pivotal to determining ice cloud radiative effect and precipitating rate. However, there is a lack of accurate ice particle effective radius (Rei) observation on the global scale to constrain its representation in climate models. In support of future mission design, here we present a modeling assessment of the sensitivity of climate simulations to Rei and quantify the impact of the proposed mission concept on reducing the uncertainty in climate sensitivity. We perturb the parameters pertaining to ice fall speed parameter and Rei in radiation scheme, respectively, in National Center for Atmospheric Research CESM1 model with a slab ocean configuration. The model sensitivity experiments show that a settling velocity increase due to a larger Rei results in a longwave cooling dominating over a shortwave warming, a global mean surface temperature decrease, and precipitation suppression. A similar competition between longwave and shortwave cloud forcing changes also exists when perturbing Rei in the radiation scheme. Linearity generally holds for the climate response for Rei related parameters. When perturbing falling snow particle size (Res) in a similar way, we find much less sensitivity of climate responses. Our quadrupling CO2 experiments with different parameter settings reveal that Rei and Res can account for changes in climate sensitivity significantly from +12.3% to −6.2%. By reducing the uncertainty ranges of Rei and Res from a factor of 2 to ±25%, a future satellite mission under design is expected to improve the climate state simulations and reduce the climate sensitivity uncertainty pertaining to ice particle size by approximately 60%. Our results highlight the importance of better observational constraints on Rei by satellite missions. ©2020. American Geophysical Union. All Rights Reserved."
"56282905200;7003379342;","Radiative effects of daily cycle of cloud frequency in past and future climates",2020,"10.1007/s00382-019-05077-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076605106&doi=10.1007%2fs00382-019-05077-5&partnerID=40&md5=a8288c8aff41c0cc4c7302ab33622d77","The daily cloud cycle or diurnal cloud cycle (DCC) and its response to global warming are critical to the Earth’s energy budget, but their radiative effects have not been systematically quantified. Toward this goal, here we analyze the radiation at the top of the atmosphere and propose a measure of the DCC radiative effect (DCCRE) as the difference between the total radiative fluxes with the full cloud cycle and its uniformly distributed cloud counterpart. When applied to the frequency of cloud occurrence, DCCRE is linked to the covariance between DCC and cloud radiative effects. Satellite observations show that the daily cloud cycle is strongly linked to pacific decadal oscillation (PDO) and climate hiatus, revealing its potential role in controlling climate variability. Climate model outputs show large inter-model spreads of DCCRE, accounting for approximately 20% inter-model spread of the cloud radiative effects. Climate models also suggest that while DCCRE is not sensitive to rising temperatures at the global scale, it can be important in certain regions. Such a framework can be used to conduct a more systematic evaluation of the DCC in climate models and observations with the goal to understand climate variability and reduce uncertainty in climate projections. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"6603081424;56567382200;22635081500;","A Global Survey of Apparent Aerosol-Cloud Interaction Signals",2020,"10.1029/2019JD031287","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078314452&doi=10.1029%2f2019JD031287&partnerID=40&md5=a14dced806d7ce9a44da943cb68fd80d","We update and expand analysis of the apparent responses to aerosol variations of the planet's cloud regimes seen by the Moderate Resolution Imaging Spectroradiometer (MODIS). We distinguish between morning aerosol loadings and afternoon clouds and consider local scales explicitly. Aerosol loading is represented by gridded aerosol optical depth (AOD) from either MODIS or a reanalysis data set, while cloud information comes exclusively from MODIS. The afternoon cloud affected quantities (CAQs) examined in conjunction with morning AOD include precipitation and cloud radiative effect, in addition to cloud properties. One analysis thrust focuses on calculating global means distinguished by morning cloud regime, of afternoon CAQs, for distinct percentiles of grid cell seasonal morning AOD distributions. When the dependence of these global means on AOD is examined, we find persistent increases in cloud radiative fluxes with AOD as predicted by classic aerosol-cloud interaction paradigms, and also deviations from expected cloud responses, especially for precipitation. The other analysis thrust involves calculations at 1° scales of logarithmic CAQ sensitivities to AOD perturbations, approximated by linear regression slopes for distinct morning cloud regime groups. While the calculations are fundamentally local, we concentrate on the prevailing sensitivity signs in statistics of the slopes at global scales. Results from this second analysis approach indicate CAQ directions of change with AOD that are largely consistent with the first approach. When using a rather simple methodology where meteorological variables are treated as if they were CAQs, no conclusive results on the potential influence of meteorology on our findings are inferred. Published 2019. This article is a US Government work and is in the public domain in the USA."
"57215534431;36796935700;56650604800;6603034566;","Solar energy estimations in india using remote sensing technologies and validation with sun photometers in urban areas",2020,"10.3390/rs12020254","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081089129&doi=10.3390%2frs12020254&partnerID=40&md5=8c72c4ad94fe2a4d4fe1c7205b6a0fb0","Solar radiation ground data is available in poor spatial resolution, which provides an opportunity and demonstrates the necessity to consider solar irradiance modeling based on satellite data. For the first time, solar energy monitoring in near real-time has been performed for India. This study focused on the assessment of solar irradiance from the Indian Solar Irradiance Operational System (INSIOS) using operational cloud and aerosol data from INSAT-3D and Copernicus Atmosphere Monitoring Service (CAMS)-Monitoring Atmospheric Composition Climate (MACC), respectively. Simulations of the global horizontal irradiance (GHI) and direct normal irradiance (DNI) were evaluated for 1 year for India at four Baseline Surface Radiation Network (BSRN) stations located in urban regions. The INSIOS system outputs as per radiative transfer model results presented high accuracy under clear-sky and cloudy conditions for GHI and DNI. DNI was very sensitive to the presence of cloud and aerosols, where even with small optical depths the DNI became zero, and thus it affected the accuracy of simulations under realistic atmospheric conditions. The median BSRN and INSIOS difference was found to vary from -93 to -49 W/m2 for GHI and -103 to -76 W/m2 for DNI under high solar energy potential conditions. Clouds were able to cause an underestimation of 40%, whereas for various aerosol inputs to the model, the overall accuracy was high for both irradiances, with the coefficient of determination being 0.99, whereas the penetration of photovoltaic installation, which exploits GHI, into urban environments (e.g., rooftop) could be effectively supported by the presented methodology, as estimations were reliable during high solar energy potential conditions. The results showed substantially high errors for monsoon season due to increase in cloud coverage that was not well-predicted at satellite and model resolutions. © 2020 by the authors."
"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."
"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."
"57033686900;7202145115;7401776640;","Is the Net Cloud Radiative Effect Constrained to be Uniform Over the Tropical Warm Pools?",2019,"10.1029/2019GL083642","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074866926&doi=10.1029%2f2019GL083642&partnerID=40&md5=c944bcb76d7286c88910735fd5f7e49f","Global radiative-convective equilibrium simulations are used to investigate the hypothesis that mutual interactions among cloud albedo, sea surface temperature gradients, and atmospheric circulation constrain the net cloud radiative effect (CRE) to be similar in convective and nonconvective regions over the tropical warm pools. We perform an experiment in which convective clouds interact naturally with the ocean and atmosphere by forming over the warmest water and shading it and an experiment in which this interaction is removed by randomizing cloud shading of the ocean. Removing the cloud shading interaction enhances sea surface temperature gradients, lateral atmospheric heat transport, and large-scale convective aggregation and produces convective clouds with much more negative net CRE. These findings support the hypothesis that feedbacks between sea surface temperature and convection are critical to obtaining similar net CRE in convective and nonconvective regions over the tropical warm pools. ©2019. American Geophysical Union. All Rights Reserved."
"7006497723;26538406800;56382795700;7003495004;8561777300;36124109400;","Trends in surface radiation and cloud radiative effect at four Swiss sites for the 1996-2015 period",2019,"10.5194/acp-19-13227-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074413836&doi=10.5194%2facp-19-13227-2019&partnerID=40&md5=fd5ae2ab8e9f9e6c31127728fac6e52d","The trends of meteorological parameters and surface downward shortwave radiation (DSR) and downward longwave radiation (DLR) were analysed at four stations (between 370 and 3580ma.s.l.) in Switzerland for the 1996-2015 period. Ground temperature, specific humidity, and atmospheric integrated water vapour (IWV) trends were positive during all-sky and cloud-free conditions. Allsky DSR and DLR trends were in the ranges of 0.6-4.3 Wm-2 decade-1 and 0.9-4.3 Wm-2 decade-1, respectively, while corresponding cloud-free trends were -2:9- 3.3 Wm-2 decade-1 and 2.9-5.4 Wm-2 decade-1. Most trends were significant at the 90% and 95% confidence levels. The cloud radiative effect (CRE) was determined using radiative-transfer calculations for cloud-free DSR and an empirical scheme for cloud-free DLR. The CRE decreased in magnitude by 0.9-3.1 Wm-2 decade-1 (only one trend significant at 90% confidence level), which implies a change in macrophysical and/or microphysical cloud properties. Between 10% and 70% of the increase in DLR is explained by factors other than ground temperature and IWV. A more detailed, long-term quantification of cloud changes is crucial and will be possible in the future, as cloud cameras have been measuring reliably at two of the four stations since 2013. © Author(s) 2019."
"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"
"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."
"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."
"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."
"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"
"57208530894;9246517900;10341067100;6602178158;7404029779;55390548700;36924136800;","A statistical and process-oriented evaluation of cloud radiative effects in high-resolution global models",2019,"10.5194/gmd-12-1679-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065033349&doi=10.5194%2fgmd-12-1679-2019&partnerID=40&md5=0d133e31002eb77225a5b1d526317774","This study evaluates the impact of atmospheric horizontal resolution on the representation of cloud radiative effects (CREs) in an ensemble of global climate model simulations following the protocols of the High Resolution Model Intercomparison Project (HighResMIP). We compare results from four European modelling centres, each of which provides data from ""standard""- and ""high""-resolution model configurations. Simulated radiative fluxes are compared with observation-based estimates derived from the Clouds and Earth's Radiant Energy System (CERES) dataset. Model CRE biases are evaluated using both conventional statistics (e.g. time and spatial averages) and after conditioning on the phase of two modes of internal climate variability, namely the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). Simulated top-of-atmosphere (TOA) and surface CREs show large biases over the polar regions, particularly over regions where seasonal sea-ice variability is strongest. Increasing atmospheric resolution does not significantly improve these biases. The spatial structure of the cloud radiative response to ENSO and NAO variability is simulated reasonably well by all model configurations considered in this study. However, it is difficult to identify a systematic impact of atmospheric resolution on the associated CRE errors. Mean absolute CRE errors conditioned on the ENSO phase are relatively large (5-10 W mĝ'2) and show differences between models. We suggest this is a consequence of differences in the parameterization of SW radiative transfer and the treatment of cloud optical properties rather than a result of differences in resolution. In contrast, mean absolute CRE errors conditioned on the NAO phase are generally smaller (0-2 W mĝ'2) and more similar across models. Although the regional details of CRE biases show some sensitivity to atmospheric resolution within a particular model, it is difficult to identify patterns that hold across all models. This apparent insensitivity to increased atmospheric horizontal resolution indicates that physical parameterizations play a dominant role in determining the behaviour of cloud-radiation feedbacks. However, we note that these results are obtained from atmosphere-only simulations and the impact of changes in atmospheric resolution may be different in the presence of coupled climate feedbacks. © Author(s) 2019. This work is distributed underthe Creative Commons Attribution 4.0 License."
"57205587578;7202208382;","Geographical and Seasonal Variability of Cloud-Radiative Feedbacks on Precipitation",2019,"10.1029/2018JD029186","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060597967&doi=10.1029%2f2018JD029186&partnerID=40&md5=438eee26259c5f1fe327079d9dc95e18","We have used observations to study the temporal covariability of precipitation and atmospheric radiative cooling (ARC, defined as positive when the atmosphere is radiatively cooled) on seasonal and longer time scales. Clouds act to decrease the globally averaged ARC, but their radiative effect on the ARC varies with latitude. Clouds decrease the ARC in the tropics, mainly by reducing the outgoing longwave radiation, but they increase the ARC in higher latitudes, primarily by increasing the downwelling longwave radiation at the surface. The temporal correlation of the zonally averaged precipitation rate and the zonally averaged ARC is about −0.7 in the tropics and +0.5 in higher latitudes, and it changes sign almost discontinuously toward the poles at approximately 30°N and 30°S. This suggests that changes in the ARC feed back negatively on precipitating tropical systems and positively on precipitating systems at higher latitudes. ©2019. American Geophysical Union. All Rights Reserved."
"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."
"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."
"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."
"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."
"8882641700;7004479957;7402781278;23013520400;","Locally Enhanced Aerosols Over a Shipping Lane Produce Convective Invigoration but Weak Overall Indirect Effects in Cloud-Resolving Simulations",2018,"10.1029/2018GL078682","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053454765&doi=10.1029%2f2018GL078682&partnerID=40&md5=63a7a2eec0558fcd3d6952b2c171aa05","The effect of aerosol emissions from an active shipping lane in the Indian Ocean is simulated using an idealized framework in a cloud-resolving model. Increased aerosol concentrations over the modeled shipping lane lead to increased cloud droplet number, cloud liquid mass, ice hydrometeor mass, and simulated radar reflectivity. The invigoration of deep convection induces mesoscale uplift and increased precipitation over the shipping lane. A predicted increase in the prevalence of both strong updrafts and radar echoes aloft is suggestive of enhanced lightning activity over the shipping lane, as observed in a recent study. Cloud radiative effects, both shortwave and longwave, are intensified over the shipping lane, but the change in the net radiative flux at top of atmosphere is not significantly different from zero. ©2018. American Geophysical Union. All Rights Reserved."
"7403276033;8225489800;57206332144;16174234500;57214087387;6602499262;6507069695;7005276494;","Reduction in 317-780 nm radiance reflected from the sunlit Earth during the eclipse of 21 August 2017",2018,"10.5194/amt-11-4373-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050669562&doi=10.5194%2famt-11-4373-2018&partnerID=40&md5=37d9c34382db03f78475819948fc3d1d","Ten wavelength channels of calibrated radiance image data from the sunlit Earth are obtained every 65 min during Northern Hemisphere summer from the EPIC (Earth Polychromatic Imaging Camera) instrument on the DSCOVR (Deep Space Climate Observatory) satellite located near the Earth-Sun Lagrange 1 point (L1), about 1.5 million km from the Earth. The L1 location permitted seven observations of the Moon's shadow on the Earth for about 3 h during the 21 August 2017 eclipse. Two of the observations were timed to coincide with totality over Casper, Wyoming, and Columbia, Missouri. Since the solar irradiances within five channels (λi = 388, 443, 551, 680, and 780 nm) are not strongly absorbed in the atmosphere, they can be used for characterizing the eclipse reduction in reflected radiances for the Earth's sunlit face containing the eclipse shadow. Five channels (λi = 317.5, 325, 340, 688, and 764 nm) that are partially absorbed in the atmosphere give consistent reductions compared to the non-absorbed channels. This indicates that cloud reflectivities dominate the 317.5-780 nm radiances reflected back to space from the sunlit Earth's disk with a significant contribution from Rayleigh scattering for the shorter wavelengths. An estimated reduction of 10 % was obtained for spectrally integrated radiance (387 to 781 nm) reflected from the sunlit Earth towards L1 for two sets of observations on 21 August 2017, while the shadow was in the vicinity of Casper, Wyoming (42.8666° N, 106.3131° W; centered on 17:44:50 UTC), and Columbia, Missouri (38.9517° N, 92.3341° W; centered on 18:14:50 UTC). In contrast, when non-eclipse days (20 and 23 August) are compared for each wavelength channel, the change in reflected light is much smaller (less than 1 % for 443 nm compared to 9 % (Casper) and 8 % (Columbia) during the eclipse). Also measured was the ratio REN(λi) of reflected radiance on adjacent non-eclipse days divided by radiances centered in the eclipse totality region with the same geometry for all 10 wavelength channels. The measured REN(443 nm) was smaller for Columbia (169) than for Casper (935), because Columbia had more cloud cover than Casper. REN(λi) forms a useful test of a 3-D radiative transfer models for an eclipse in the presence of optically thin clouds. Specific values measured at Casper with thin clouds are REN(340 nm) = 475, REN(388 nm) = 3500, REN(443 nm) = 935, REN(551 nm) = 5455, REN(680 nm) = 220, and REN(780 nm) = 395. Some of the variability is caused by changing cloud amounts within the moving region of totality during the 2.7 min needed to measure all 10 wavelength channels. © 2018 Author(s)."
"56293796000;16636807900;11939929300;7005808242;","Sensitivity of Radiative-Convection Equilibrium to Divergence Damping in GFDL-FV3-Based Cloud-Resolving Model Simulations",2018,"10.1029/2017MS001225","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050931187&doi=10.1029%2f2017MS001225&partnerID=40&md5=74ac62e131175619909f001bdcb709c6","Using a nonhydrostatic model based on a version of Geophysical Fluid Dynamics Laboratory's FV3 dynamical core at a cloud-resolving resolution in radiative-convective equilibrium (RCE) configuration, the sensitivity of the mean RCE climate to the magnitude and scale-selectivity of the divergence damping is explored. Divergence damping is used to reduce small-scale noise in more realistic configurations of this model. This sensitivity is tied to the strength (and width) of the convective updrafts, which decreases (increases) with increased damping and acts to organize the convection, dramatically drying out the troposphere and increasing the outgoing longwave radiation. Increased damping also results in a much-broadened precipitation probability distribution and larger extreme values, as well as reduction in cloud fraction, which correspondingly decreases the magnitude of shortwave and longwave cloud radiative effects. Solutions exhibit a monotonic dependence on the strength of the damping and asymptotically converge to the inviscid limit. While the potential dependence of RCE simulations on resolution and microphysical assumptions are generally appreciated, these results highlight the potential significance of the choice of subgrid numerical diffusion in the dynamical core. ©2018. The Authors."
"57201338569;19638935200;56424145700;48661551300;25823927100;7410070663;","Comparison of three ice cloud optical schemes in climate simulations with community atmospheric model version 5",2018,"10.1016/j.atmosres.2018.01.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044357014&doi=10.1016%2fj.atmosres.2018.01.004&partnerID=40&md5=3086c41bbf59a6bce0812a8b4da216aa","A newly implemented Baum-Yang scheme for simulating ice cloud optical properties is compared with existing schemes (Mitchell and Fu schemes) in a standalone radiative transfer model and in the global climate model (GCM) Community Atmospheric Model Version 5 (CAM5). This study systematically analyzes the effect of different ice cloud optical schemes on global radiation and climate by a series of simulations with a simplified standalone radiative transfer model, atmospheric GCM CAM5, and a comprehensive coupled climate model. Results from the standalone radiative model show that Baum-Yang scheme yields generally weaker effects of ice cloud on temperature profiles both in shortwave and longwave spectrum. CAM5 simulations indicate that Baum-Yang scheme in place of Mitchell/Fu scheme tends to cool the upper atmosphere and strengthen the thermodynamic instability in low- and mid-latitudes, which could intensify the Hadley circulation and dehydrate the subtropics. When CAM5 is coupled with a slab ocean model to include simplified air-sea interaction, reduced downward longwave flux to surface in Baum-Yang scheme mitigates ice-albedo feedback in the Arctic as well as water vapor and cloud feedbacks in low- and mid-latitudes, resulting in an overall temperature decrease by 3.0/1.4 °C globally compared with Mitchell/Fu schemes. Radiative effect and climate feedback of the three ice cloud optical schemes documented in this study can be referred for future improvements on ice cloud simulation in CAM5. © 2018 Elsevier B.V."
"35086136600;6602111828;","Design and verification of a new monochromatic thermal emission component for the I3RC community Monte Carlo model",2018,"10.1175/JAS-D-17-0251.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044669188&doi=10.1175%2fJAS-D-17-0251.1&partnerID=40&md5=9ea84554ace6c50adba7d008e840ba77","The Intercomparison of 3D Radiation Codes (I3RC) community Monte Carlo model has been extended to include a source of photon emission from the surface and atmosphere, thereby making it capable of simulating scalar radiative transfer in a 3D scattering, absorbing, and emitting domain with both internal and external sources. The theoretical basis, computational implementation, verification of the internal emission, and computational performance of the resulting model, the ""IMC+emission,"" is presented. Thorough verification includes fundamental tests of reciprocity and energy conservation, comparison to analytical solutions, and comparison with another 3D model, the Spherical Harmonics Discrete Ordinate Method (SHDOM). All comparisons to fundamental tests and analytical solutions are accurate to within the precision of the simulations-typically better than 0.05%. Comparison cases to SHDOM were typically within a few percent, except for flux divergence near cloud edges, where the effects of grid definition between the two models manifest themselves. Finally, the model is applied to the established I3RC case 4 cumulus cloud field to provide a benchmark result, and computational performance and strong and weak scaling metrics are presented. The outcome is a thoroughly vetted, publicly available, open-source benchmark tool to study 3D radiative transfer from either internal or external sources of radiation at wavelengths for which scattering, emission, and absorption are important. © 2018 American Meteorological Society."
"56898397000;55544443300;55686667100;","Dependence of Arctic climate on the latitudinal position of stationary waves and to high-latitudes surface warming",2017,"10.1007/s00382-017-3543-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011826959&doi=10.1007%2fs00382-017-3543-y&partnerID=40&md5=77e5481276a77ec11510c4cbd464ab1e","Previous studies suggest large uncertainties in the stationary wave response under global warming. Here, we investigate how the Arctic climate responds to changes in the latitudinal position of stationary waves, and to high-latitudes surface warming that mimics the effect of Arctic sea ice loss under global warming. To generate stationary waves in an atmospheric model coupled to slab ocean, a series of experiments is performed where the thermal forcing with a zonal wavenumber-2 (with zero zonal-mean) is prescribed at the surface at different latitude bands in the Northern Hemisphere. When the stationary waves are generated in the subtropics, the cooling response dominates over the warming response in the lower troposphere due to cloud radiative effects. Then, the low-level baroclinicity is reduced in the subtropics, which gives rise to a poleward shift of the eddy driven jet, thereby inducing substantial cooling in the northern high latitudes. As the stationary waves are progressively generated at higher latitudes, the zonal-mean climate state gradually becomes more similar to the integration with no stationary waves. These differences in the mean climate affect the Arctic climate response to high-latitudes surface warming. Additional surface heating over the Arctic is imposed to the reference climates in which the stationary waves are located at different latitude bands. When the stationary waves are positioned at lower latitudes, the eddy driven jet is located at higher latitude, closer to the prescribed Arctic heating. As baroclinicity is more effectively perturbed, the jet shifts more equatorward that accompanies a larger reduction in the poleward eddy transport of heat and momentum. A stronger eddy-induced descending motion creates greater warming over the Arctic. Our study calls for a more accurate simulation of the present-day stationary wave pattern to enhance the predictability of the Arctic warming response in a changing climate. © 2017, Springer-Verlag Berlin Heidelberg."
"7410069943;56532611600;8848948500;","Observational characteristics of cloud radiative effects over three arid regions in the Northern Hemisphere",2017,"10.1007/s13351-017-6166-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028332867&doi=10.1007%2fs13351-017-6166-7&partnerID=40&md5=3abfefa6bbb4d28a8cb58cc565f67eb3","Cloud–radiation processes play an important role in regional energy budgets and surface temperature changes over arid regions. Cloud radiative effects (CREs) are used to quantitatively measure the aforementioned climatic role. This study investigates the characteristics of CREs and their temporal variations over three arid regions in central Asia (CA), East Asia (EA), and North America (NA), based on recent satellite datasets. Our results show that the annual mean shortwave (SW) and net CREs (SWCRE and NCRE) over the three arid regions are weaker than those in the same latitudinal zone of the Northern Hemisphere. In most cold months (November–March), the longwave (LW) CRE is stronger than the SWCRE over the three arid regions, leading to a positive NCRE and radiative warming in the regional atmosphere–land surface system. The cold-season mean NCRE at the top of the atmosphere (TOA) averaged over EA is 4.1 W m–2, with a positive NCRE from November to March, and the intensity and duration of the positive NCRE is larger than that over CA and NA. The CREs over the arid regions of EA exhibit remarkable annual cycles due to the influence of the monsoon in the south. The TOA LWCRE over arid regions is closely related to the high-cloud fraction, and the SWCRE relates well to the total cloud fraction. In addition, the relationship between the SWCRE and the low-cloud fraction is good over NA because of the considerable occurrence of low cloud. Further results show that the interannual variation of TOA CREs is small over the arid regions of CA and EA, but their surface LWCREs show certain decreasing trends that correspond well to their decreasing total cloud fraction. It is suggested that combined studies of more observational cloud properties and meteorological elements are needed for indepth understanding of cloud–radiation processes over arid regions of the Northern Hemisphere. © 2017, The Chinese Meteorological Society and Springer-Verlag GmbH Germany."
"7402284525;7005275092;9434771700;6603907571;35568718600;","A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5",2017,"10.5194/gmd-10-2525-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021766223&doi=10.5194%2fgmd-10-2525-2017&partnerID=40&md5=efbf7945afbda37ff55cfe42da285146","Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18-0.8 μm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 μm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere. The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20-40 % depending on the solar zenith angles and occur throughout the atmosphere. Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components - wavelength integration, scattering, and averaging over cloud fields - all have comparably small errors. More accurate solutions with Solar-J come with increased computational costs, about 5 times that of RRTMG-SW for a single atmosphere. There are options for reduced costs or computational acceleration that would bring costs down while maintaining improved fidelity and balanced errors. © Author(s) 2017."
"57190127262;37006854700;57194499087;57194383828;6604032554;","A postprocessing methodology for direct normal irradiance forecasting using cloud information and aerosol load forecasts",2017,"10.1175/JAMC-D-16-0297.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020433000&doi=10.1175%2fJAMC-D-16-0297.1&partnerID=40&md5=aa004ff179903f2ce510f1836ff4394b","A method for direct normal irradiance (DNI) forecasting for specific sites is proposed. It is based on the combination of a numerical weather prediction (NWP) model, which provides cloud information, with radiative transfer simulations fed with external aerosol forecasts. The NWP model used is the ECMWF Integrated Forecast System, and the radiative transfer information has been obtained from the Library of Radiative Transfer (libRadtran). Two types of aerosol forecasts have been tested: the global Monitoring Atmospheric Composition and Climate (MACC) model, which predicts five major components of aerosols, and the Dust Regional Atmospheric Model (BSC-DREAM8b) added to a fixed background calculated as the 20th percentile of the monthly mean of AERONET 2.0 observations from a different year. The methodology employed is valid for all meteorological situations, providing a stable and continuous DNI curve. The performance of the combined method has been evaluated against DNI observations and compared with the pure ECMWF forecasts at eight locations in the southern half of mainland Spain and the Canary Islands, which received high loadings of African dust for 2013 and 2014. Results for 1-day forecasts are presented. Although clouds play a major role, aerosols have a significant effect, but at shorter time scales. The combination of ECMWF and MACC forecasts gives the best global results, improving the DNI forecasts in events with high aerosol content. The regional BSC-DREAM8b yields good results for some extremely high dust conditions, although more reliable predictions, valid for any aerosol conditions, are provided by the MACC model. © 2017 American Meteorological Society."
"26653789100;57203108896;","A cloud feedback emulator (CFE, version 1.0) for an intermediate complexity model",2017,"10.5194/gmd-10-945-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014004958&doi=10.5194%2fgmd-10-945-2017&partnerID=40&md5=50acf6667919894955a837b7863bf21e","The dominant source of inter-model differences in comprehensive global climate models (GCMs) are cloud radiative effects on Earth's energy budget. Intermediate complexity models, while able to run more efficiently, often lack cloud feedbacks. Here, we describe and evaluate a method for applying GCM-derived shortwave and longwave cloud feedbacks from 4 × CO2 and Last Glacial Maximum experiments to the University of Victoria Earth System Climate Model. The method generally captures the spread in top-of-the-atmosphere radiative feedbacks between the original GCMs, which impacts the magnitude and spatial distribution of surface temperature changes and climate sensitivity. These results suggest that the method is suitable to incorporate multi-model cloud feedback uncertainties in ensemble simulations with a single intermediate complexity model. © Author(s) 2017."
"55704388300;24281186100;7403221533;24437285800;6602185497;","Cloud parameter retrievals from Meteosat and their effects on the shortwave radiation at the surface",2017,"10.1080/01431161.2017.1280630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010333204&doi=10.1080%2f01431161.2017.1280630&partnerID=40&md5=bd3ce29c977b59388431d10212a721fe","A method based on Spinning Enhanced Visible and Infrared Imager (SEVIRI) measured reflectance at 0.6 and 3.9 µm is used to retrieve the cloud optical thickness (COT) and cloud effective radius (re) over the Iberian Peninsula. A sensitivity analysis of simulated retrievals to the input parameters demonstrates that the cloud top height is an important factor in satellite retrievals of COT and re with uncertainties around 10% for small values of COT and re; for water clouds these uncertainties can be greater than 10% for small values of re. The uncertainties found related with geometries are around 3%. The COT and re are assessed using well-known satellite cloud products, showing that the method used characterize the cloud field with more than 80% (82%) of the absolute differences between COT (re) mean values of all clouds (water plus ice clouds) centred in the range from ±10 (±10 µm), with absolute bias lower than 2 (2 μm) for COT (re) and root mean square error values lower than 10 (8 μm) for COT (re). The cloud water path (CWP), derived from satellite retrievals, and the shortwave cloud radiative effect at the surface (CRESW) are related for high fractional sky covers (Fsc >0.8), showing that water clouds produce more negative CRESW than ice clouds. The COT retrieved was also related to the cloud modification factor, which exhibits reductions and enhancements of the surface SW radiation of the order of 80% and 30%, respectively, for COT values lower than 10. A selected case study shows, using a ground-based sky camera that some situations classified by the satellite with high Fsc values correspond to situations of broken clouds where the enhancements actually occur. For this case study, a closure between the liquid water path (LWP) obtained from the satellite retrievals and the same cloud quantity obtained from ground-based microwave measurements was performed showing a good agreement between both LWP data set values. © 2017 Informa UK Limited, trading as Taylor & Francis Group."
"56182620500;7401796996;8629713500;7404829395;7004364155;","A clear-sky radiation closure study using a one-dimensional radiative transfer model and collocated satellite-surface-reanalysis data sets",2016,"10.1002/2016JD025823","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003674371&doi=10.1002%2f2016JD025823&partnerID=40&md5=8c9410d0691d596c45c93a04c8c94dd1","Earth's climate is largely determined by the planet's energy budget, i.e., the balance of incoming and outgoing radiation at the surface and top of atmosphere (TOA). Studies have shown that computing clear-sky radiative fluxes are strongly dependent on atmospheric state variables, such as temperature and water vapor profiles, while the all-sky fluxes are greatly influenced by the presence of clouds. NASA-modeled vertical profiles of temperature and water vapor are used to derive the surface radiation budget from Clouds and Earth Radiant Energy System (CERES), which is regarded as one of the primary sources for evaluating climate change in climate models. In this study, we evaluate the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalyzed clear-sky temperature and water vapor profiles with newly generated atmospheric profiles from Department of Energy Atmospheric Radiation Measurement (ARM)-merged soundings and Aura Microwave Limb Sounder retrievals at three ARM sites. The temperature profiles are well replicated in MERRA-2 at all three sites, whereas tropospheric water vapor is slightly dry below ~700 hPa. These profiles are then used to calculate clear-sky surface and TOA radiative fluxes from the Langley-modified Fu-Liou radiative transfer model (RTM). In order to achieve radiative closure at both the surface and TOA, the ARM-measured surface albedos and aerosol optical depths are adjusted to account for surface inhomogeneity. In general, most of the averaged RTM-calculated surface downward and TOA upward shortwave and longwave fluxes agree within ~5 W/m2 of the observations, which is within the uncertainties of the ARM and CERES measurements. Yet still, further efforts are required to reduce the bias in calculated fluxes in coastal regions. ©2016. American Geophysical Union. All Rights Reserved."
"12761291000;57112070700;","How finely do we need to represent the stratocumulus radiative effect?",2016,"10.1002/qj.2828","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977106553&doi=10.1002%2fqj.2828&partnerID=40&md5=6872c6e813f3481c96c81e522584db14","Cloud radiative cooling at the top of stratocumulus is crucial to power turbulence in the well-mixed, stratocumulus-topped atmospheric boundary layer (ABL). The present work uses a large-eddy simulation model to understand how finely the spatial structure of the cloud radiative effect (CRE) has to be represented in order to sustain a stratocumulus-topped ABL in equilibrium. We first explore whether the vertical structure of the CRE can be simplified, and it appears that the cloud radiative cooling in the upper part of the cloud is essential to the existence of the equilibrium stratocumulus, and that the CRE has to be represented in some detail around the cloud top to sustain this equilibrium. Second, we investigate how the horizontal heterogeneities of CRE impact the stratocumulus equilibrium. Horizontal homogenization of the radiative cooling has a small thinning impact on the stratocumulus-topped ABL. Because of the nonlinear dependence of the cloud radiative cooling on the liquid water path (LWP), computing the CRE from the mean liquid water profile overestimates the vertically integrated CRE and yields an unstable, ever-growing ABL. Assuming a simple sub-domain distribution of LWP and adjusting the cloud radiative cooling accordingly is sufficient to correct for this overestimation and sustain a stratocumulus equilibrium. Finally, we check that vertical and horizontal simplifications of the CRE are compatible, which opens perspectives for its representation in bulk models and larger-scale models. © 2016 Royal Meteorological Society"
"37087012900;12144198300;57205397413;6701729202;","A synthetic data set of high-spectral-resolution infrared spectra for the Arctic atmosphere",2016,"10.5194/essd-8-199-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969749436&doi=10.5194%2fessd-8-199-2016&partnerID=40&md5=cbe675f0ea1469a73aef9595ced3f674","Cloud microphysical and macrophysical properties are critical for understanding the role of clouds in climate. These properties are commonly retrieved from ground-based and satellite-based infrared remote sensing instruments. However, retrieval uncertainties are difficult to quantify without a standard for comparison. This is particularly true over the polar regions, where surface-based data for a cloud climatology are sparse, yet clouds represent a major source of uncertainty in weather and climate models. We describe a synthetic high-spectralresolution infrared data set that is designed to facilitate validation and development of cloud retrieval algorithms for surface-and satellite-based remote sensing instruments. Since the data set is calculated using pre-defined cloudy atmospheres, the properties of the cloud and atmospheric state are known a priori. The atmospheric state used for the simulations is drawn from radiosonde measurements made at the North Slope of Alaska (NSA) Atmospheric Radiation Measurement (ARM) site at Barrow, Alaska (71.325° N, 156.615° W), a location that is generally representative of the western Arctic. The cloud properties for each simulation are selected from statistical distributions derived from past field measurements. Upwelling (at 60 km) and downwelling (at the surface) infrared spectra are simulated for 260 cloudy cases from 50 to 3000 cm-1 (3.3 to 200 μm) at monochromatic (line-by-line) resolution at a spacing of ∼0.01 cm-1 using the Line-by-line Radiative Transfer Model (LBLRTM) and the discrete-ordinate-method radiative transfer code (DISORT). These spectra are freely available for interested researchers from the NSF Arctic Data Center data repository (doi:10.5065/D61J97TT). © 2016 Author(s)."
"9249239700;57144839900;7501439334;7003278104;36150977900;56130997600;57044397100;6603126554;54787680700;","The impacts of precipitating cloud radiative effects on ocean surface evaporation, precipitation, and ocean salinity in coupled GCM simulations",2016,"10.1002/2016JD024911","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983407620&doi=10.1002%2f2016JD024911&partnerID=40&md5=898a0316110fd113bef262a3093affc4","The coupled global climate model (GCM) fidelity in representing upper ocean salinity including near sea surface bulk salinity (SSS) is evaluated in this study, with a focus on the Pacific Ocean. The systematic biases in ocean surface evaporation (E) minus precipitation (P) and SSS are found to be fairly similar in the twentieth century simulations of the Coupled Model Intercomparison Phase 3 (CMIP3) and Phase 5 (CMIP5) relative to the observations. One of the potential causes of the CMIP model biases is the missing representation of the radiative effects of precipitating hydrometeors (i.e., snow) in most CMIP models. To examine the radiative effect of cloud snow on SSS, sensitivity experiments with and without such effect are conducted by the National Center for Atmospheric Research-coupled Community Earth System Model (CESM). This study investigates the difference in SSS between sensitivity experiments and its relationship with atmospheric circulation, E-P and air-sea heat fluxes. It is found that the exclusion of the cloud snow radiative effect in CESM produces weaker Pacific trade winds, resulting in enhanced precipitation, reduced evaporation, and a reduction of the upper ocean salinity in the tropical and subtropical Pacific. The latter results in an improved comparison with climatological upper ocean bulk salinity. The introduction of cloud snow also altered the budget terms that maintain the time-mean salinity in the mixed layer. © 2016. American Geophysical Union. All Rights Reserved."
"16064843400;7102953444;6602733593;7003841561;55636624100;56152199100;","Interannual variation of global net radiation flux as measured from space",2016,"10.1002/2015JD024112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978796234&doi=10.1002%2f2015JD024112&partnerID=40&md5=08a6e58c2d81476c720739a2ba214bba","The global net radiation flux (NRF) in and out of the climate system at the top of the atmosphere (TOA) varies at interannual time scales, reflecting the complexity of the processes responsible for attaining global energy equilibrium. These processes are investigated in this study using the previously unexplored data acquired by a bolometric type sensor installed in the PICARD microsatellite. The obtained anomalies in the NRF (PICARD-NRF) are compared to the global NRF changes at the TOA measured by the Clouds and Earth’s Radiant Energy System mission (CERES-NRF). The interanual PICARD-NRF is strongly correlated with the matching period CERES-NRF; the bootstrapped correlation at the 95%(+0.85 and +0.97) confidence intervals is +0.93. Consistency in the interannual variability in the NRF derived by two completely independent measurement systems enhances confidence in the estimated magnitude of these variations. To reveal the possible drivers of the NRF interannual variability, the NRF values were compared with the multivariate El Niño-Southern Oscillation index. © 2016. American Geophysical Union. All Rights Reserved."
"6603345878;8067118800;8117864800;56032970700;7401945370;","Numerical experiments to analyze cloud microphysical processes depicted in vertical profiles of radar reflectivity of warm clouds",2015,"10.1175/JAS-D-15-0053.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84950257122&doi=10.1175%2fJAS-D-15-0053.1&partnerID=40&md5=b7f9540b55799e79a0fd73c078c86f84","Information about microphysical processes in warm clouds embedded in satellite measurements must be untangled to be used to improve the parameterization in global models. In this paper, the relationship between vertical profiles of horizontally averaged radar reflectivity Zm and cloud optical depth from cloud top τd was investigated using a hybrid cloud microphysical model and a forward simulator of satellite measurements. The particle size distributions were explicitly simulated using a bin method in a kinematic framework. In contrast to previous interpretations of satellite-observed data, three patterns of the Zm-τd relationship related to microphysical processes were identified. The first is related to the autoconversion process, which causes Zm to increase upward with decreasing τd. Before the initiation of surface precipitation, Zm increases downward with τd in the upper part of the cloud, which is considered to be a second characteristic pattern and is caused by the accretion process. The appearance of this pattern corresponds to the initiation of efficient production of raindrops in the cloud. The third is related to the sedimentation and evaporation of raindrops causing Zm to decrease downward with τd in the lower part of the Zm-τd relationship. It was also found that the bulk collection efficiency has a partially positive correlation with the slope factor of Zm with regard to τd and that the slope factor could be a gross measure of the collection efficiency in partial cases. This study also shows that differences in the aerosol concentration modulate the duration of these three patterns and change the slope factor of Zm. © 2015 American Meteorological Society."
"55314995700;10240710000;10243650000;56350198800;","Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming",2015,"10.5194/acpd-15-17527-2015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028451174&doi=10.5194%2facpd-15-17527-2015&partnerID=40&md5=b88755757efc9777a4d12585e8f8e8a6","This study investigates the effect of sea ice reduction on Arctic cloud cover in historical simulations with the coupled atmosphere-ocean general circulation model MIROC5. During simulated global warming since the 1970s, the Arctic sea ice extent has reduced substantially, particularly in September. This simulated reduction is consistent with satellite observation results. However, the Arctic cloud cover increases significantly during October at grids with significant reductions in sea ice because of the enhanced heat and moisture flux from the underlying ocean. Cloud fraction increases in the lower troposphere. However, the cloud fraction in the surface thin layers just above the ocean decreases despite the increased moisture because the surface air temperature rises strikingly in the thin layers and the relative humidity decreases. As the cloud cover increases, the cloud radiative effect in surface downward longwave radiation (DLR) increases by approximately 40-60 % compared to a change in clear-sky surface DLR. These results suggest that an increase in the Arctic cloud cover as a result of a reduction in sea ice could further melt the sea ice and enhance the feedback processes of the Arctic amplification in future projections. © Author(s) 2015."
"55630942000;","The use of aircraft for meteorological research in the United Kingdom",2014,"10.1002/met.1448","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84892472781&doi=10.1002%2fmet.1448&partnerID=40&md5=6697657f48ed6d3f4be36478002f1711","Atmospheric observations from aircraft have played an important role in meteorological research for many years; this paper presents an overview of meteorological research done with research aircraft in the United Kingdom. Key developments from throughout the history of meteorological research flying in the United Kingdom are presented, along with highlights of UK atmospheric research flying done in the last decade using the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft. The work presented includes research into thermodynamics, cloud processes, atmospheric aerosol, radiative transfer and atmospheric chemistry. Research aircraft provide a unique platform for the observation of atmospheric processes, allowing targeted measurement of specific parameters at a range of altitudes throughout the atmosphere. These measurements have improved greatly the understanding of the Earth's atmosphere, and the impact of these measurements has been seen through improvements in the representation of physical processes within numerical weather prediction (NWP) and climate models. Research aircraft have also been used extensively for the calibration and validation of remote sensing measurements, providing a unique test-bed for satellite observations. This research has led to improved use of satellite observations that have enhanced greatly how the atmosphere is viewed. Many developments in atmospheric research would not have been possible without the use of aircraft measurements, and these measurements will continue to play a key role in future developments of meteorological observation and prediction, as the complexity and resolution of weather and climate models increases. © 2014 Royal Meteorological Society."
"26631543900;7403931916;7201826462;6603631763;7003668116;","Development of a GOES-R advanced baseline imager solar channel radiance simulator for ice clouds",2013,"10.1175/JAMC-D-12-0180.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876782371&doi=10.1175%2fJAMC-D-12-0180.1&partnerID=40&md5=04938b1e7795b338754b176c9b1b333f","This paper describes the development of an ice cloud radiance simulator for the anticipated Geostationary Operational Environmental Satellite R (GOES-R) Advanced Baseline Imager (ABI) solar channels. The simulator is based on the discrete ordinates radiative transfer (DISORT) model. A set of correlated k-distribution (CKD) models is developed for the ABI solar channels to account for atmospheric trace gas absorption. The CKD models are based on the ABI spectral response functions and also consider when multiple gases have overlapping absorption. The related errors of the transmittance profile are estimated on the basis of the exact line-by-line results, and it is found that errors in transmittance are less than 0.2% for all but one of the ABI solar channels. The exception is for the 1.378-μm channel, centered near a strong water vapor absorption band, for which the errors are less than 2%. For ice clouds, the band-averaged bulk-scattering properties for each ABI [and corresponding Moderate Resolution Imaging Spectroradiometer (MODIS)] solar channel are derived using an updated single-scattering property database of both smooth and severely roughened ice particles, which include droxtals, hexagonal plates, hexagonal hollow and solid columns, three-dimensional hollow and solid bullet rosettes, and several types of aggregates. The comparison shows close agreement between the radiance simulator and the benchmark model, the line-by-line radiative transfer model (LBLRTM)1DISORT model. The radiances of the ABI and corresponding MODIS measurements are compared. The results show that the radiance differences between the ABI and MODIS channels under ice cloud conditions are likely due to the different band-averaged imaginary indices of refraction. © 2013 American Meteorological Society."
"54788308700;7003908632;12764954600;","An evaluation of arctic cloud and radiation processes simulated by the limited-area version of the Global Multiscale Environmental Model (GEM-LAM)",2011,"10.1080/07055900.2011.604266","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84055211873&doi=10.1080%2f07055900.2011.604266&partnerID=40&md5=95fb035616e7e45d950c4a1ad887834d","Cloud and radiation processes simulated by the limited area version of the Global Environmental Multiscale Model (GEM-LAM) are evaluated for the period September 1997 to October 1998 over the western Arctic Ocean. This period coincides with the Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment. Surface downwelling solar and terrestrial radiation, surface albedo, vertically integrated water vapour, liquid water path, precipitation, cloud cover and cloud radiative forcing simulated by GEM-LAM are evaluated against the SHEBA observation dataset. GEM-LAM simulates the annual cycle of the downwelling shortwave (SWD) and longwave (LWD) radiation at the surface reasonably well, as well as precipitable water at monthly and daily time scales. Cloud fraction at daily and monthly time scales is not captured well by the model. During winter, GEM-LAM produces a large negative bias for the vertically integrated liquid water path and a positive bias for cloud fraction. As a result, cloud radiative forcing at the surface and LWD radiation are well reproduced but for the wrong reasons because these two biases have an opposing effect on their magnitudes. During summer, the model underestimates the surface albedo, thus resulting in a substantial overestimation of the cloud radiative forcing at the surface. Precipitation is underestimated during winter and overestimated during summer and spring. The sensitivity of the results to the effective radius of ice crystals and the parameterization of cloud phase is also discussed."
"57206454204;7404837587;26032538900;53664709200;36179190000;","Study of distinctive regional features of surface solar radiation in north and east China",2011,"10.1007/s13351-011-0408-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80053099626&doi=10.1007%2fs13351-011-0408-x&partnerID=40&md5=85dcd3f7e01121d2de038c8201c2fe1b","Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance. Variations in solar radiation incident at the earth's surface profoundly affect the human and terrestrial environment, including the climate change. To provide useful information for predicting the future climate change in China, distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007. Multiple models, such as the plane-parallel radiative transfer model, empirical and statistical models, and correlation and regression analysis methods are used in the study. The results are given as follows. (1) During 1961-2007, the total SSR in North China went through a process from quickly ""dimming to slowly ""dimming, while in East China, a significant transition from ""dimming to ""brightening occurred. Although there are some differences between the two regional variation trends, long-term variations in SSR in the two regions are basically consistent with the observation worldwide. (2) Between the 1960s and 1980s, in both North and East China, aerosols played a critical role in the radiation dimming. However, after 1989, different variation trends of SSR occurred in North and East China, indicating that aerosols were not the dominant factor. (3) Cloud cover contributed less to the variation of SSR in North China, but was the major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening, especially in the ""remarkable brightening"" period, with its contribution as high as 70%. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2011."
"55597088322;55199339300;57212997273;","Remote sensing of water cloud properties from MSG/SEVIRI nighttime imagery",2011,"10.1016/j.rse.2010.10.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650893525&doi=10.1016%2fj.rse.2010.10.015&partnerID=40&md5=8f4c2dc97f2f181f3e81a806601b0542","The Spinning Enhanced Visible and Infrared Imager (SEVIRI) measurements from the Meteosat Second Generation (MSG) satellites enable global monitoring of the distribution of clouds during day and night, with a spatial, temporal and spectral resolution that allows for better understanding of the role of clouds in global radiation budget and in climate in general. A method to retrieve cloud properties from nighttime SEVIRI measurements is described in this paper. The method is applicable to single-layer water clouds over sea surfaces and it is based on the inversion of a forward theoretical radiative transfer model, that simulates the radiances reaching the SEVIRI infrared detectors from a specified configuration of the earth-cloud-atmosphere system. This model accounts for scattering and absorption processes in the assumed horizontally homogeneous adiabatic cloud layer. For the inversion of this model, artificial neural networks techniques have been used in this work. The main advantage that these techniques provide is their low computational cost, which makes them suitable for the implementation of operational retrieval procedures. Results obtained by the proposed method are compared with the values provided by the CloudSat derived 2B-TAU product, and those derived from NOAA-AVHRR nighttime imagery, obtaining good agreements. © 2010 Elsevier Inc."
"6504033814;7006246996;40361595000;","Transect method for antarctic cloud property retrieval using AVHRR data",2011,"10.1080/01431161003745624","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79957592403&doi=10.1080%2f01431161003745624&partnerID=40&md5=dc64751d22d709796996e0d78e733373","For studies of Antarctic climate change, the Advanced Very High Resolution Radiometer (AVHRR) offers a time series spanning more than two decades, with numerous overpasses per day from converging polar orbits, and with radiometrically calibrated thermal infrared channels. However, over the Antarctic Plateau, standard multispectral application of AVHRR data for cloud optical property retrieval with individual pixels is problematic due to poor scene contrasts and measurement uncertainties. We present a method that takes advantage of rapid changes in radiances at well-defined cloud boundaries. We examine a transect of AVHRR-measured radiances in the three thermal infrared channels across a boundary between cloudy and cloud-free parts of the image. Using scatter diagrams, made from the data along this transect, of the brightness temperature differences between channels 3 and 4, and channels 4 and 5, it is possible to fit families of radiative transfer solutions to the data to estimate cloud effective temperature, thermodynamic phase, and effective particle radius. The major approximation with this method is that along such a transect, cloud water path has considerable spatial variability, while effective radius, phase, and cloud temperature have much less variability. To illustrate this method, two AVHRR images centred about the South Pole are analysed. The two images are chosen based on their differing contrasts in brightness temperature between clear and cloud-filled pixels, to demonstrate that our method can work with varying cloud top heights. In one image the data are consistent with radiative transfer simulations using ice cloud. In the other, the data are inconsistent with ice cloud and are well simulated with supercooled liquid water cloud at 241.5 K. This method therefore has potential for climatological investigation of the radiatively important phase transition in the extremely cold and pristine Antarctic environment. © 2011 Taylor & Francis."
"24780687700;7403203783;8437626600;56412340900;7202950780;","Multiangular polarized characteristics of optically thin cirrus in the visible and near-infrared spectral region",2010,"10.1175/2009JAS2996.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953344203&doi=10.1175%2f2009JAS2996.1&partnerID=40&md5=9013e04848268dc0ccdf184ed9209215","Optically thin cirrus play a key role in the earth's radiation budget and global climate change. Their radiative effects depend critically on the thin cirrus optical and microphysical properties. In this paper, in-homogeneous hexagonal monocrystals (IHMs), which consist of a pure hexagon with spherical air bubble or aerosol inclusions, are applied to calculate the single-scattering properties of individual ice crystals. The multiangular polarized characteristics of optically thin cirrus for the 0.865-and 1.38-μm spectral bands are simulated on the basis of an adding-doubling radiative transfer program. The sensitivity of total and polarized reflectance at the top of the atmosphere (TOA) to different aerosol, cirrus, and surface parameters is studied. A new sensitivity index is introduced to further quantify the sensitivity study. The TOA polarized reflectance measured by the Polarization and Directionality of the Earth's Reflectance (POLDER) instruments is compared to simulated TOA total and polarized reflectance. The test results are reasonable, although small deviations caused by the change of aerosol properties and thin cirrus optical thickness do exist. Finally, on the basis of the sensitivity study, a conceptual approach is suggested to simultaneously retrieve thin cirrus clouds' optical thickness, ice particle shape, and the underlying aerosol optical thickness using the TOA total and polarized reflectance of the 0.865-and 1.38-μm spectral bands measured at multiple viewing angles. © 2010 American Meteorological Society."
"7005435915;6602494687;","Russian studies of atmospheric radiation in 2003-2006",2009,"10.1134/S0001433809020042","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65549085801&doi=10.1134%2fS0001433809020042&partnerID=40&md5=32c115080591e92d3fc9debbedcde481","The Russian Radiation Commission, in cooperation with interested departments and institutions, has held two international symposia on atmospheric radiation for the Commonwealth of Independent States in the recent past. The participants of the symposia discussed problems that are currently particularly relevant in atmospheric physics: radiative transfer, atmospheric optics, greenhouse gases, clouds, aerosols, climate changes, remote sensing, and new observational data. Five directions covering the complete spectrum of investigations on atmospheric radiation are presented in this report. © Pleiades Publishing, Ltd. 2009."
"57190749913;7201646465;6602654938;7202970886;","Stochastic radiative transfer on modeled cloud fields",2009,"10.1109/LGRS.2008.2007814","https://www.scopus.com/inward/record.uri?eid=2-s2.0-65049085635&doi=10.1109%2fLGRS.2008.2007814&partnerID=40&md5=f6abd782bb40e88dd4e966f55485330b","Several efforts are currently underway to improve cloud-radiation parameterizations in Global Climate Models (GCMs) by incorporating statistical properties of the cloud field. Although some radiation parameterizations, which are already computationally costly, now incorporate subgrid scale variability in cloud properties, they are not yet capable of using this information in their calculations of the 3-D radiation fields. Before drastic changes are made to such algorithms to incorporate cloudcloud radiation interactions, the impact of including realistic high-resolution cloud distributions on the shortwave fluxes should be assessed. This letter provides a framework for carrying out such assessments, including a new methodology that blends a stochastic radiative transfer model, high-resolution cloud fields from a mesoscale meteorological model, and a threshold and object identification technique applied to cloud water content fields. This process provides a link between the radiative fluxes calculated in GCMs, where clouds occur at a subgrid scale, and the highly resolved cloud fields in a regional climate model, which can provide cloud field statistics. Two case studies are described herein. © 2009 IEEE."
"8687853700;7404433688;35265615300;55386235300;","Retrieval of liquid water path inside nonprecipitating clouds using TMI measurements",2008,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-58049209431&partnerID=40&md5=6c792f06614d3d3ef035f2281fb1621b","Quantitative estimates of liquid water path (LWP) in clouds using satellite measurements are critical to understanding of cloud properties and the assessment of global climate change. In this paper, the relationship between microwave brightness temperature (TB) and LWP in the nonprecipitating clouds is studied by using satellite microwave measurements from the TRMM Microwave Imager (TMI) onboard the Tropical Rainfall Measuring Mission (TRMM), together with a radiative transfer model for microwave radiance calculations. Radiative transfer modeling shows that the sensitivity is higher at both 37.0- and 85.5-GHz horizontal polarization channels for the LWP retrievals. Also, the differences between the retrieved values responding to TBs of various channels and the theoretical values are displayed by the model. Based upon above simulations, with taking into account the factor of resolution and retrieval bias for a single channel, a nonprecipitating cloud LWP in the summer subtropical marine environment retrieval algorithm is formulated by the combination of the two TMI horizontal polarization channels, 37.0 and 85.5 GHz. Moreover, by using TMI measurements (1B11), this algorithm is applied to retrieving respectively LWPs for clear sky, nonprecipitating clouds, and typhoon precipitating clouds. In the clear sky case, the LWP changes from -1 to 1 g m-2, and its mean value is about 10-5 g m-2. It indicates that, using this combination retrieval algorithm, there are no obvious systemic deviations when the LWP is low enough. The LWP values varying from 0 to 1000 g m-2 in nonprecipitating clouds are reasonable, and its distribution pattern is very similar to the detected results in the visible channel of Visible and Infrared Scanner (VIRS) on the TRMM. In typhoon precipitating clouds, there is much more proportion of high LWP in the mature phase than the early stage. When surface rainfall rate is lower than 5 mm h-1, the LWP increases with increasing rainfall rate."
"6701394887;56250117600;56999946500;","A model to predict cloud density from midlatitude atmospheric soundings for microwave radiative transfer applications",2006,"10.1029/2006RS003463","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33847074658&doi=10.1029%2f2006RS003463&partnerID=40&md5=ebbcef403f2811195c2012f897c6614e","A new model for computing cloud liquid density from vertical profiles of meteorological variables, provided by either radio soundings or atmospheric analyses, is proposed. It has been developed for local-scale applications, in particular for a midlatitude environment such as the Mediterranean area, although the methodology can be easily extended to other climatic zones. The model has been derived from a numerical simulation of a cloudy event that occurred in the Mediterranean basin, performed by means of a microphysical mesoscale meteorological simulation package. The validation has been mainly carried out through a comparison between brightness temperature simulations in cloudy conditions and satellite microwave radiometric data over the Mediterranean Sea. The simulations have been performed by applying a radiative transfer scheme to a set of atmospheric profiles consisting of both European Centre for Medium-Range Weather Forecasts (ECMWF) analyses and radiosonde measurements. Two literature models have been considered as benchmarks. The new model reproduces the Special Sensor Microwave Imager brightness temperature statistics in the Mediterranean area fairly well. Furthermore, it predicts an integrated liquid water content which is in agreement with that supplied by the ECMWF analyses. Copyright 2006 by the American Geophysical Union."
"7004055178;57199054070;","Radiative transfer in shallow cumulus cloud fields: Observations and first analysis with the Diram instrument during the BBC-2 field campaign in May 2003",2006,"10.1016/j.atmosres.2005.09.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749343342&doi=10.1016%2fj.atmosres.2005.09.006&partnerID=40&md5=d9176de0395d88e0e3f9bc620012a759","The cloud albedo is a crucial parameter in radiation budget studies, and is one of the main forcings in climate. We have designed and made a device, Diram (directional radiance distribution measurement device), which not only measures reflection and transmission of solar radiation through clouds, but which also determines the radiance distribution. The construction contains 42 sensors, consisting of a collimation system and a detector, which are mounted in two domes (21 in each). The collimators reduce the field of view of each sensor to ∼7°. The domes were mounted on top and below of the Meteo France Merlin IV research aircraft. The 42 signals were continuously logged with a frequency of 10 Hz during a number of flights in the framework of the Baltex Bridge-2 campaign at Cabauw (The Netherlands) in May 2003. The Diram instrument provided radiances during in situ observations of cumulus and (broken) stratocumulus clouds and detected anisotropic effects in solar radiation scattered by clouds which are due to different cloud geometries and which are related to microphysical cloud properties. Microphysical cloud properties were obtained from the Gerber PVM100A optical sensor aboard the aircraft. Liquid water content and particle surface area were logged with a frequency of 200 Hz. Data have been collected from a total of 10 days in different weather conditions (clear sky, broken cumulus, stratocumulus and multilayered cloud). A clear sky test of the Diram indicated that the device was able to reproduce the Rayleigh scattering pattern. During flights in stratocumulus fields, strongly anisotropic patterns were observed. The DIRAM observations confirm that in thin clouds a strong preference for forward scattering is observed in the transmitted radiation field while for thicker clouds the pattern becomes more isotropic, with a slightly brighter centre relative to the limb direction. © 2006 Elsevier B.V. All rights reserved."
"6602228395;7003811919;","Potential for dust storm detection through aerosol radiative forcing related to atmospheric parameters",2006,"10.1109/IGARSS.2006.163","https://www.scopus.com/inward/record.uri?eid=2-s2.0-34948818659&doi=10.1109%2fIGARSS.2006.163&partnerID=40&md5=b0c03df45b4eb836ec531a9841e95f94","The implications of climatic effects due to aerosols with a large variability like mineral dust serve as indicators of dust events and are examined. Airborne mineral dust can influence the climate by altering the radiative properties of the atmosphere. For instance, aerosols in the form of dust particles reflect the incoming solar radiation to space, thereby reducing the amount of radiation available to the ground. This is known as 'direct' radiative forcing of aerosols. Aerosols also serve as cloud condensation nuclei (CCN) and change the cloud albedo and microphysical properties of clouds, known as 'indirect' radiative forcing of aerosols. Direct and indirect radiative forcing by mineral dust are observed over a desert case study in China as well as a highly vegetated case study over Nile Delta, Egypt, using boundary layer dispersion (BLD), albedo, sensible heat flux (SHF), latent heat flux (LHF) and out going long wave radiation (OLR) parameters. During the presence of the dust event, shortwave fluxes largely decrease accompanied by an abrupt increase in the down-welling long wave fluxes resulting in surface forcing. This leads to absorption of the shortwave and long wave radiations resulting in a positive forcing in the top of the atmosphere. In this research we are focusing on the radiative impacts of the dust over some meteorological parameters."
"7402056142;7102223138;35512883100;23162993500;","A finite element-spherical harmonics model for radiative transfer in inhomogeneous clouds. Part II. Some applications",2004,"10.1016/j.atmosres.2004.03.021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-8644273954&doi=10.1016%2fj.atmosres.2004.03.021&partnerID=40&md5=4204981796333023dbc78edba51870c6","EVENT has been used to examine the effects of 3D cloud structure, distribution, and inhomogeneity on the scattering of visible solar radiation and the resulting 3D radiation field. Large eddy simulation and aircraft measurements are used to create realistic cloud fields which are continuous or broken with smooth or uneven tops. The values, patterns and variance in the resulting downwelling and upwelling radiation from incident visible solar radiation at different angles are then examined and compared to measurements. The results from EVENT confirm that 3D cloud structure is important in determining the visible radiation field, and that these results are strongly influenced by the solar zenith angle. The results match those from other models using visible solar radiation, and are supported by aircraft measurements of visible radiation, providing confidence in the new model. © 2004 Elsevier B.V. All rights reserved."
"6504033814;7006246996;7102577095;","Infrared radiative properties of the Antarctic plateau from AVHRR data. Part I: Effect of the snow surface",2004,"10.1175/1520-0450(2004)043<0350:IRPOTA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-1842865107&doi=10.1175%2f1520-0450%282004%29043%3c0350%3aIRPOTA%3e2.0.CO%3b2&partnerID=40&md5=c20f3f9ba6576594ce003ce03de439fa","The effective scene temperature, or ""brightness temperature,"" measured in channel 3 (3.5-3.9 μm) of the Advanced Very High Resolution Radiometer (AVHRR) is shown to be sensitive, in principle, to the effective particle size of snow grains on the Antarctic plateau, over the range of snow grain sizes reported in field studies. In conjunction with a discrete ordinate method radiative transfer model that couples the polar atmosphere with a scattering and absorbing snowpack, the thermal infrared channels of the AVHRR instrument can, therefore, be used to estimate effective grain size at the snow surface over Antarctica. This is subject to uncertainties related to the modeled top-of-atmosphere bidirectional reflectance distribution function resulting from the possible presence of sastrugi and to lack of complete knowledge of snow crystal shapes and habits as they influence the scattering phase function. However, when applied to NOAA-11 and NOAA-12 AVHRR data from 1992, the snow grain effective radii of order 50 μm are retrieved, consistent with field observations, with no apparent discontinuity between two spacecraft having different viewing geometries. Retrieved snow grain effective radii are 10-20-μm larger when the snow grains are modeled as hexagonal solid columns rather than as spheres with a Henyey-Greenstein phase function. Despite the above-mentioned uncertainties, the retrievals are consistent enough that one should be able to monitor climatically significant changes in surface snow grain size due to major precipitation events. It is also shown that a realistic representation of the surface snow grain size is critical when retrieving the optical depth and effective particle radius of clouds for the optically thin clouds most frequently encountered over the Antarctic plateau. © 2004 American Meteorological Society."
"6603452942;6603133549;","Analysis and prediction of cirrus-top altitude and ice water path in a mesoscale area",2003,"10.1175/1520-0450(2003)042<1092:AAPOCA>2.0.CO;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141849064&doi=10.1175%2f1520-0450%282003%29042%3c1092%3aAAPOCA%3e2.0.CO%3b2&partnerID=40&md5=0011abb80b7086197a5622df9d77f7f5","Vertical distributions of clouds have been a focus of many studies, motivated by their importance in radiative transfer processes in climate models. This study examines the horizontal distribution of cirrus clouds by means of satellite imagery analyses and numerical weather prediction model forecasts. A ground-truth dataset based on two aircraft mission periods flying particle probes through cirrus over a ground-based cloud radar is developed. Particle probe measurements in the cirrus clouds are used to compute ice water content and radar reflectivity averages in short time periods (25-30 s). Relationships for ice water content as a function of reflectivity are developed for 6-K ambient temperature categories. These relationships are applied to the radar-measured shorterm-averaged reflectivities to compute vertical profiles of ice water content, which are vertically integrated over the depth of the observed cirrus clouds to form ice water path estimates. These and cloud-top height are compared with the same quantities as retrieved by the Geostationary Operational Environmental Satellite (GOES) level-2B algorithm applied to four channels of GOES-8 imagery measurements. The agreement in cloud-top height is reasonable (generally less than 2-km difference). The ice water path retrievals are smaller in magnitude than the radar estimates, and this difference grows with increasing cirrus thickness. Comparisons of a sequence of the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5) predictions and GOES level-2B retrievals of ice cloud tops for the convectively active second mission period showed that the MM5 cirrus areal extent was somewhat greater than the GOES depictions. Cloud-top height ranges were similar. MM5 is capable of producing ice water path magnitudes similar to the radar estimates, but the GOES retrievals are much more limited. Ninety-eight percent of the GOES grid points had ice water paths no greater than 60 g m-2, as compared with 74% for MM5. Ten percent of MM5 points had ice water content >200 g m-2, as compared with 0.07% for GOES retrievals. Based on this study, we conclude that GOES level-2B cloud-top retrievals are a reliable tool for prediction evaluations but the algorithm's retrievals of ice water path are not."
"7102371345;7003865921;","PICASSO-CENA: combined active-passive sensing from space",1999,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033331801&partnerID=40&md5=84631338b81ed6f76b7069dd673a5543","Clouds and aerosols affect the Earth's radiation budget by scattering incoming solar radiation back to space and absorbing outgoing thermal radiation. Current uncertainties in the nature and magnitude of these effects limit our understanding of the climate system and the potential for global climate change. PICASSO-CENA is a recently approved mission within NASA's ESSP program which will obtain new measurements of clouds and aerosols to improve predictions of climate change and its impacts. PICASSO-CENA will fly in near formation with the already planned EOS PM satellite to provide a coincident set of data on aerosol and cloud properties, radiative fluxes, and atmospheric state essential for accurate quantification of aerosol and cloud radiative effects. The PICASSO-CENA payload consists of a two-wavelength polarization-sensitive lidar and three co-aligned passive instruments. Data from these four instruments will be used to measure the vertical distributions of aerosols and clouds in the atmosphere, as well as optical and physical properties of aerosols and clouds which influence the Earth's radiation budget. Data from PICASSO-CENA and from EOS PM will be combined to provide improved determinations of surface and atmospheric radiative fluxes. PICASSO-CENA is being developed as a partnership between NASA and the French space agency CNES, and is planned to launch in early 2003."
"57203400519;","Atmospheric radiation",1991,"10.1002/rog.1991.29.s1.56","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026286276&doi=10.1002%2frog.1991.29.s1.56&partnerID=40&md5=8b64355776d8970c026146dd7be6c1c0","The topics to be covered have been classified (somewhat arbitrarily) into the following five categories although there is obviously considerable overlap among them. These are: i) Radiation Modelling; ii) Clouds and Radiation; iii) Radiative Effects in Dynamics and Climate; iv) Radiation Budget and Aerosol Effects; v) Gaseous Absorption Particulate Scattering and Surface Reflection. The bibliography accompanying this review has also been separated by topic although some papers have undoubtedly been misclassified. -from Author"
"7102018821;57198199168;","Recent progress in atmospheric radiation.",1984,"10.1175/1520-0477-65.5.475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021564275&doi=10.1175%2f1520-0477-65.5.475&partnerID=40&md5=9f39fb340615911df6f6679f6a1e6d2a","This report contains summaries and highlights of the papers presented at the Fifth Conference on Atmospheric Radiation. Papers spanning the subjects of satellite remote sensing, interactions of radiation and general circulation, effects of clouds and aerosols on climate, radiation budget studies from satellites, some aspects of radiative transfer and radiation measurements, and solar energy applications were presented.-from Authors"
"57189904994;57214457029;57189906561;57189905509;57189900852;57218557802;","Long-term (2008–2017) analysis of atmospheric composite aerosol and black carbon radiative forcing over a semi-arid region in southern India: Model results and ground measurement",2020,"10.1016/j.atmosenv.2020.117840","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089505819&doi=10.1016%2fj.atmosenv.2020.117840&partnerID=40&md5=f8b2efd1c6ee413038e134ccd2cc6956","To achieve an in-depth understanding of radiative forcing due to aerosols is a crucial challenge for climate change studies. The first-ever long-term measurement of direct shortwave composite and black carbon aerosol radiative properties over a semi-arid region, Anantapur, in southern India is presented. Long-term variations in Aerosol Optical Depth (AOD) and Black Carbon (BC) mass concentration from December 2007 to November 2017 are discussed with specific emphasis on intra-seasonal variation in aerosol optical properties, meteorology, transport pathways, and their implications for direct short wave radiative forcing over Anantapur. The intra-seasonal mean AOD showed strong seasonal dependence with the highest (0.47 ± 0.03) during summer and lowest (0.28 ± 0.03) during the monsoon. Meanwhile, the intra-seasonal mean (±σ) BC mass concentration was about 3.57 ± 0.45, 2.60 ± 0.58, 1.22 ± 0.18 and 2.24 ± 0.28 μg m−3 during winter, summer, monsoon and post-monsoon respectively. Furthermore, there is an obvious temporal variation in intra-seasonal BC mass concentration during the dry season (winter and summer). To be more specific, the intra-seasonal mean (±σ) BC mass concentration before 2012 (after 2012) during the dry season was about 3.37 ± 0.7 μg m−3 (2.80 ± 0.58 μg m−3), respectively. Concentration weighted trajectory analyses (CWT) revealed that the air masses originated from the continental and polluted environments located in the central and northern parts of India (except monsoon), in regulating BC mass concentration over measurement location. Further, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) derived aerosol vertical extinction profiles (532 nm) showed that majority aerosols (>250 Mm−1) are confined within 2 km from the surface during winter while in summer particles are distributed throughout the profile (~6 km) with extinction coefficient varying between 200 and 250 Mm−1. The Santa Barbara Discrete Ordinate Radiative Transfer (SBDART) model estimated intra-seasonal mean direct shortwave composite aerosol radiative forcing (DARF) in the atmosphere (ATM) was about 31.13 ± 3.36, 34.82 ± 3.89, 17.10 ± 1.15, and 17.44 ± 1.81 Wm-2 during winter, summer, monsoon and post-monsoon, respectively. The positive signs of ATM forcing in all seasons indicate a warming of the atmosphere, and the corresponding heating rate was around a factor of two higher during the dry season (0.92 ± 0.12 Kday−1) than the wet season (monsoon and post-monsoon) (0.49 ± 0.04 Kday−1). The intra-seasonal mean BC forcing in ATM before 2012 (After 2012) during the dry season was about 24.14 ± 2.85Wm-2(20.09 ± 2.59Wm-2), respectively. The contribution of BC alone to the composite forcing during the study period over the station was ~68%. These findings would be helpful for regional climate studies and making air pollution control policy over the region. © 2020 Elsevier Ltd"
"57189461717;57199051943;57212214712;57212210733;57204462393;","Asymmetry of Cloud Vertical Structures and Associated Radiative Effects in Typhoon over the Northwest Pacific Based on CloudSat Tropical Cyclone Dataset",2020,"10.1007/s13143-019-00159-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076207107&doi=10.1007%2fs13143-019-00159-0&partnerID=40&md5=4b840a830e382a4f16bc0ae856658854","The clouds’ macro-, microphysical vertical structures and radiative effects in 4 shear-relative quadrants of typhoon over the northwest Pacific during development, maturity and extinction stages are studied based on CloudSat Tropical Cyclone dataset and China Meteorological Administration tropical cyclone dataset from 2nd June 2006 to 31th December 2015. The typhoon cloud is in an asymmetric “mushroom” shape, with the downshear quadrants (in particular of the downshear left quadrant (DL)) have denser clouds than the upshear quadrants. Cloud ice water content mainly distributes near typhoon center with wide vertical range (6–17 km). A large number of ice particles with small sizes are gathering in high levels, while small amount of ice particles with large sizes are gathering in low levels. As typhoon matures, the number concentration and size of cloud ice particles in inner ring increases, especially in the DL quadrant; while in the upshear left (UL) quadrant, a larger amount of ice particles with bigger sizes are transport to high levels (above 16 km) by deeper convection near storm center. The shortwave (longwave) cloud radiative effects (CRE) is mainly heating (cooling) upper layer atmosphere between 10 km and 17 km (between 14 km and 17 km), and the net CRE on atmosphere is heating almost at any levels in typhoon. The strongest heating of shortwave CRE and net CRE, as well as the strongest cooling of longwave CRE are in the DL quadrant at development stage and in the UL quadrant at maturity stage in inner core of storms. The existences of typhoon clouds mainly decrease solar radiation penetrating to the earth surface and increase longwave radiation absorbed by the whole atmosphere in typhoon’s inner core, and they are generally stronger in downshear (especially in DL) quadrants, except the maturity stage when the UL quadrant performs the strongest shortwave CRE on the surface and longwave CRE on the atmosphere in typhoon’s inner core. © 2019, Korean Meteorological Society and Springer Nature B.V."
"56909327200;7201784177;","Quantifying the Impact of Wind and Surface Humidity-Induced Surface Heat Exchange on the Circulation Shift in Response to Increased CO2",2020,"10.1029/2020GL088053","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091483387&doi=10.1029%2f2020GL088053&partnerID=40&md5=20432cc1d740d57d75462f1fd301b08c","We extend the locking technique to separate the poleward shift of the atmospheric circulation in response to quadrupled CO2 into contributions from (1) CO2 increase, (2) cloud radiative effects, and (3) wind and surface humidity-induced surface heat exchange. In aquaplanet simulations, wind and surface humidity-induced surface heat exchange accounts for 30–60% of the Hadley cell edge and midlatitude eddy-driven jet shift. The increase of surface specific humidity dominates and mostly follows global mean warming. Consistent with previous work the remaining shift is attributed to cloud radiative effects. Across CMIP5 models the intermodel variance in the austral winter circulation shift in response to quadrupled CO2 is significantly correlated with the response of the subtropical-subpolar difference of surface heat exchange. The results highlight the dominant role of surface heat exchange for future circulation changes. ©2020. American Geophysical Union. All Rights Reserved."
"57209471004;7103204204;6603382350;6508213402;7005174340;","Reassessment of shortwave surface cloud radiative forcing in the Arctic: Consideration of surface-albedo-cloud interactions",2020,"10.5194/acp-20-9895-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092286419&doi=10.5194%2facp-20-9895-2020&partnerID=40&md5=3b932f3002f6160e30936fcba56019b1","The concept of cloud radiative forcing (CRF) is commonly applied to quantify the impact of clouds on the surface radiative energy budget (REB). In the Arctic, specific radiative interactions between microphysical and macrophysical properties of clouds and the surface strongly modify the warming or cooling effect of clouds, complicating the estimate of CRF obtained from observations or models. Clouds tend to increase the broadband surface albedo over snow or sea ice surfaces compared to cloud-free conditions. However, this effect is not adequately considered in the derivation of CRF in the Arctic so far. Therefore, we have quantified the effects caused by surface-albedo-cloud interactions over highly reflective snow or sea ice surfaces on the CRF using radiative transfer simulations and below-cloud airborne observations above the heterogeneous springtime marginal sea ice zone (MIZ) during the Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) campaign. The impact of a modified surface albedo in the presence of clouds, as compared to cloud-free conditions, and its dependence on cloud optical thickness is found to be relevant for the estimation of the shortwave CRF. A method is proposed to consider this surface albedo effect on CRF estimates by continuously retrieving the cloud-free surface albedo from observations under cloudy conditions, using an available snow and ice albedo parameterization. Using ACLOUD data reveals that the estimated average shortwave cooling by clouds almost doubles over snow-and ice-covered surfaces (-62 Wm-2 instead of-32 Wm-2), if surface-albedo-cloud interactions are considered. As a result, the observed total (shortwave plus longwave) CRF shifted from a warming effect to an almost neutral one. Concerning the seasonal cycle of the surface albedo, it is demonstrated that this effect enhances shortwave cooling in periods when snow dominates the surface and potentially weakens the cooling by optically thin clouds during the summertime melting season. These findings suggest that the surface-albedo-cloud interaction should be considered in global climate models and in long-term studies to obtain a realistic estimate of the shortwave CRF to quantify the role of clouds in Arctic amplification. © 2020 Author(s)."
"9249239700;7403282069;7404829395;36150977900;55644692200;56130997600;57208765667;6603126554;57144839900;","An Overview of CMIP5 and CMIP6 Simulated Cloud Ice, Radiation Fields, Surface Wind Stress, Sea Surface Temperatures, and Precipitation Over Tropical and Subtropical Oceans",2020,"10.1029/2020JD032848","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089533575&doi=10.1029%2f2020JD032848&partnerID=40&md5=76e633008c19b84c78f8f2f0229fc664","The potential links between ice water path (IWP), radiation, circulation, sea surface temperature (SST), and precipitation over the Pacific and Atlantic Oceans resulting from the falling ice radiative effects (FIREs) are examined from Coupled Model Intercomparison Project phase 5 (CMIP5) and phase 6 (CMIP6) historical simulations. The latter is divided into two subsets with (SON6) and without FIREs (NOS6) in CMIP6. Improvement in nonfalling cloud ice (~20 g m−2) is noticeable over convective regions in CMIP6 relative to CMIP5. The inclusion of FIREs in SON6 subset may contribute to reduce biases of overestimated outgoing longwave radiation and downward surface shortwave and underestimated reflected shortwave at the top of the atmosphere (TOA) by magnitudes of ~8 W m−2 over convective regions against CERES, compared to NOS6 subset. The reduced biases in radiative fluxes in convective regions stabilize the atmosphere and lead to circulation, SST, cloud, and precipitation changes over the trade wind regions, as seen from improved radiative fluxes (~15 W m−2), surface wind stress biases, SST (~0.8 K), and precipitation (1 mm day−1) biases. The significant improvement from NOS6 to SON6 leads to improved multimodel means for CMIP6 relative to CMIP5 for radiation fields over the trade wind regions but the degradation over convective zones is attributed to NOS6 subset. The results suggest that other sources of uncertainty and deficiencies in climate models may play significant roles for reducing discrepancies although FIREs, via radiation-circulation coupling, may be one of the factors that help to reduce regional biases. ©2020. American Geophysical Union. All Rights Reserved."
"12040335900;57193831923;57214319291;37117659000;56537463000;7404829395;55814053500;57214318091;","Effect of Arctic clouds on the ice-albedo feedback in midsummer",2020,"10.1002/joc.6469","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078599306&doi=10.1002%2fjoc.6469&partnerID=40&md5=ba37bda8e4e91d3e89d75109d01b467c","The Arctic clouds should be an important factor that affects the summertime sea ice. By reflecting the incoming solar radiation before it reaches the surface, the Arctic clouds may prevent the surface from absorbing tremendous solar radiation due to the reduced sea ice. This cloud effect will lead to intervene the feedback relation between the solar radiation and the sea ice change. However, few studies have quantitatively investigated the Arctic cloud effect on the ice-albedo feedback. This study found that the Arctic clouds regulate the melting speed of sea ice in midsummer months (June to August) based on the data from multiple sources, that is, satellite, reanalysis, and climate models. During this period, the fraction of Arctic clouds with the net radiative cooling effect is almost invariable with sea ice reduction. However, despite of the steady cloud fraction in the midsummer months, the shortwave cloud radiative effect (total-sky minus clear-sky absorbed shortwave radiation) was found to significantly increase with the reduced sea ice concentration (0.64 W m−2%−1 in CERES, 0.73 W m−2%−1 in ERA5). This is because the clouds present more contrast of albedo with the sea ice-free ocean than the sea ice-covered ocean. Finally, our analyses show that the Arctic clouds are nearly halving the strength of the ice-albedo feedback in the midsummer months. These results imply that the sea ice reduction could have been much faster in the past decades in the absence of the cloud effect found here. © 2020 Royal Meteorological Society"
"57187615700;7004214645;57212478693;22986631300;7102976560;7003777747;24472400800;12240390300;6602988199;","Response of surface shortwave cloud radiative effect to greenhouse gases and aerosols and its impact on summer maximum temperature",2020,"10.5194/acp-20-8251-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089126717&doi=10.5194%2facp-20-8251-2020&partnerID=40&md5=97a006d20ae50d6114407f50f1e0ddb3","Shortwave cloud radiative effects (SWCREs), defined as the difference of the shortwave radiative flux between all-sky and clear-sky conditions at the surface, have been reported to play an important role in influencing the Earth's energy budget and temperature extremes. In this study, we employed a set of global climate models to examine the SWCRE responses to CO2, black carbon (BC) aerosols, and sulfate aerosols in boreal summer over the Northern Hemisphere. We found that CO2 causes positive SWCRE changes over most of the NH, and BC causes similar positive responses over North America, Europe, and eastern China but negative SWCRE over India and tropical Africa. When normalized by effective radiative forcing, the SWCRE from BC is roughly 3-5 times larger than that from CO2. SWCRE change is mainly due to cloud cover changes resulting from changes in relative humidity (RH) and, to a lesser extent, changes in cloud liquid water, circulation, dynamics, and stability. The SWCRE response to sulfate aerosols, however, is negligible compared to that for CO2 and BC because part of the radiation scattered by clouds under all-sky conditions will also be scattered by aerosols under clear-sky conditions. Using a multilinear regression model, it is found that mean daily maximum temperature (Tmax) increases by 0.15 and 0.13K per watt per square meter (Wm..2) increase in local SWCRE under the CO2 and BC experiment, respectively. When domain-averaged, the contribution of SWCRE change to summer mean Tmax changes was 10 %-30% under CO2 forcing and 30 %-50% under BC forcing, varying by region, which can have important implications for extreme climatic events and socioeconomic activities. © 2020 Copernicus GmbH. All rights reserved."
"57217068878;18434033000;52364737200;54931083200;56736820800;6701363731;6602537415;","Investigating the sensitivity to resolving aerosol interactions in downscaling regional model experiments with WRFv3.8.1 over Europe",2020,"10.5194/gmd-13-2511-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086022901&doi=10.5194%2fgmd-13-2511-2020&partnerID=40&md5=601fd0bd2e5c01ba0c0fd3aa31fdd5af","In this work we present downscaling experiments with the Weather Research and Forecasting model (WRF) to test the sensitivity to resolving aerosol-radiation and aerosol-cloud interactions on simulated regional climate for the EURO-CORDEX domain. The sensitivities mainly focus on the aerosol-radiation interactions (direct and semi-direct effects) with four different aerosol optical depth datasets (Tegen, MAC-v1, MACC, GOCART) being used and changes to the aerosol absorptivity (single scattering albedo) being examined. Moreover, part of the sensitivities also investigates aerosol-cloud interactions (indirect effect). Simulations have a resolution of 0.44 and are forced by the ERA-Interim reanalysis. A basic evaluation is performed in the context of seasonal-mean comparisons to ground-based (E-OBS) and satellite-based (CM SAF SARAH, CLARA) benchmark observational datasets. The impact of aerosols is calculated by comparing it against a simulation that has no aerosol effects. The implementation of aerosol-radiation interactions reduces the direct component of the incoming surface solar radiation by 20 %-30% in all seasons, due to enhanced aerosol scattering and absorption. Moreover the aerosol-radiation interactions increase the diffuse component of surface solar radiation in both summer (30 %-40 %) and winter (5 %-8 %), whereas the overall downward solar radiation at the surface is attenuated by 3 %-8 %. The resulting aerosol radiative effect is negative and is comprised of the net effect from the combination of the highly negative direct aerosol effect (-17 to-5Wm-2) and the small positive changes in the cloud radiative effect (C5Wm-2), attributed to the semi-direct effect. The aerosol radiative effect is also stronger in summer (-12Wm-2) than in winter (-2Wm-2).We also show that modelling aerosol-radiation and aerosol-cloud interactions can lead to small changes in cloudiness, mainly regarding low-level clouds, and circulation anomalies in the lower and mid-troposphere, which in some cases, mainly close to the Black Sea in autumn, can be of statistical significance. Precipitation is not affected in a consistent pattern throughout the year by the aerosol implementation, and changes do not exceed-5% except for the case of unrealistically absorbing aerosol. Temperature, on the other hand, systematically decreases by-0.1 to-0.5 °C due to aerosol-radiation interactions with regional changes that can be up to-1.5 °C. © 2020 Authors."
"7410069943;22982141200;55220443400;","Distinctive spring shortwave cloud radiative effect and its inter-annual variation over southeastern China",2020,"10.1002/asl.970","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083253005&doi=10.1002%2fasl.970&partnerID=40&md5=866b158957de773408245c522e028ace","The shortwave cloud radiative effect (SWCRE) plays a critical role in the earth's radiation balance, and its global mean magnitude is much larger than the warming effect induced by greenhouse gases. This study investigates the SWCRE at the top of the atmosphere and its inter-annual variation over southeastern China (SEC) using satellite retrievals and ERA-Interim reanalysis data. The results show that in this region the largest SWCRE with the maximum intensity up to −120 W·m−2 occurs in spring and is also the strongest between 60°S and 60°N. The domain-averaged intensity of SWCRE is much larger than the longwave cloud radiative effect (LWCRE), suggesting the dominant cooling role of SWCRE in the regional atmosphere–surface system. The spring SWCRE over SEC shows a weak increasing trend and its anomalies in most years exceed those of LWCRE during 2000–2017. This means that SWCRE also plays a dominant role in the inter-annual variation of regional cloud radiative effects. Over SEC, low- to mid-level ascending motion and water vapor convergence during spring favor the generation and maintenance of cloud water, leading to strong SWCRE. Statistical analysis shows that the spatial pattern and intensity of the spring SWCRE are well correlated with the low- to mid-level ascending motion and water vapor convergence. The temporal correlation coefficient between domain-averaged spring SWCRE and 850–500-hPa vertical velocity is.76 during 2000–2017. The long-term variation in spring SWCRE over SEC can be inferred to some extent from regional ascending motion and associated large-scale circulations. © 2020 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57203874129;13403622000;57200612374;56905280300;14020798200;","Importance of orography for Greenland cloud and melt response to atmospheric blocking",2020,"10.1175/JCLI-D-19-0527.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090192254&doi=10.1175%2fJCLI-D-19-0527.1&partnerID=40&md5=c1c8f4bfa592eae03fa91579b1f347cf","More frequent high pressure conditions associated with atmospheric blocking episodes over Greenland in recent decades have been suggested to enhance melt through large-scale subsidence and cloud dissipation, which allows more solar radiation to reach the ice sheet surface. Here we investigate mechanisms linking high pressure circulation anomalies to Greenland cloud changes and resulting cloud radiative effects, with a focus on the previously neglected role of topography. Using reanalysis and satellite data in addition to a regional climate model, we show that anticyclonic circulation anomalies over Greenland during recent extreme blocking summers produce cloud changes dependent on orographic lift and descent. The resulting increased cloud cover over northern Greenland promotes surface longwave warming, while reduced cloud cover in southern and marginal Greenland favors surface shortwave warming. Comparison with an idealized model simulation with flattened topography reveals that orographic effects were necessary to produce area-averaged decreasing cloud cover since the mid-1990s and the extreme melt observed in the summer of 2012. This demonstrates a key role for Greenland topography in mediating the cloud and melt response to large-scale circulation variability. These results suggest that future melt will depend on the pattern of circulation anomalies as well as the shape of the Greenland Ice Sheet. © 2020 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses)."
"35509639400;57204833386;49664027700;7201504886;","Sugar, Gravel, Fish, and Flowers: Dependence of Mesoscale Patterns of Trade-Wind Clouds on Environmental Conditions",2020,"10.1029/2019GL085988","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083484048&doi=10.1029%2f2019GL085988&partnerID=40&md5=ff264d32716d7a34346cadf0bb8893dc","Trade-wind clouds exhibit a large diversity of spatial organizations at the mesoscale. Over the tropical western Atlantic, a recent study has visually identified four prominent mesoscale patterns of shallow convection, referred to as flowers, fish, gravel, and sugar. We show that these four patterns can be identified objectively from satellite observations by analyzing the spatial distribution of infrared brightness temperatures. By applying this analysis to 19 years of data, we examine relationships between cloud patterns and large-scale environmental conditions. This investigation reveals that on daily and interannual timescales, the near-surface wind speed and the strength of the lower-tropospheric stability discriminate the occurrence of the different organization patterns. These results, combined with the tight relationship between cloud patterns, low-level cloud amount, and cloud-radiative effects, suggest that the mesoscale organization of shallow clouds might change under global warming. The role of shallow convective organization in determining low-cloud feedback should thus be investigated. ©2020. The Authors."
"55537426400;57204914522;7201485519;24329376600;","Fixed anvil temperature feedback: Positive, zero, or negative?",2020,"10.1175/JCLI-D-19-0108.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091673748&doi=10.1175%2fJCLI-D-19-0108.1&partnerID=40&md5=74a67425c0c82340e6c793d03f81d3c8","The fixed anvil temperature (FAT) theory describes a mechanism for how tropical anvil clouds respond to global warming and has been used to argue for a robust positive longwave cloud feedback. A constant cloud anvil temperature, due to increased anvil altitude, has been argued to lead to a ''zero cloud emission change'' feedback, which can be considered positive relative to the negative feedback associated with cloud anvil warming when cloud altitude is unchanged. Here, partial radiative perturbation (PRP) analysis is used to quantify the radiative feedback caused by clouds that follow the FAT theory (FAT-cloud feedback) and to set this in the context of other feedback components in two atmospheric general circulation models. The FAT-cloud feedback is positive in the PRP framework due to increasing anvil altitude, but because the cloud emission does not change, this positive feedback is cancelled by an equal and opposite component of the temperature feedback due to increasing emission from the cloud. To incorporate this cancellation, the thermal radiative damping with fixed relative humidity and anvil temperature (T-FRAT) decomposition framework is proposed for longwave feedbacks, in which temperature, fixed relative humidity, and FAT-cloud feedbacks are combined. In T-FRAT, the cloud feedback under the FAT constraint is zero, while that under the proportionately higher anvil temperature (PHAT) constraint is negative. The change in the observable cloud radiative effect with FAT-cloud response is also evaluated and shown to be negative due to so-called cloud masking effects. It is shown that ''cloud masking'' is a misleading term in this context, and these effects are interpreted more generally as ''cloud climatology effects''. © 2020 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses)."
"7405367162;12645612500;57212818622;35263384600;","Cloud detection over snow and ice with oxygen A- A nd B-band observations from the Earth Polychromatic Imaging Camera (EPIC)",2020,"10.5194/amt-13-1575-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083098679&doi=10.5194%2famt-13-1575-2020&partnerID=40&md5=83ff3d3643b20d788ee98a8927d8ed81","Satellite cloud detection over snow and ice has been difficult for passive remote sensing instruments due to the lack of contrast between clouds and cold/bright surfaces; cloud mask algorithms often heavily rely on shortwave infrared (IR) channels over such surfaces. The Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) does not have infrared channels, which makes cloud detection over snow and ice surfaces even more challenging. This study investigates the methodology of applying EPIC's two oxygen absorption band pair ratios in the A band (764, 780 nm) and B band (688, 680 nm) for cloud detection over the snow and ice surfaces. We develop a novel elevation and zenith-angle-dependent threshold scheme based on radiative transfer model simulations that achieves significant improvements over the existing algorithm. When compared against a composite cloud mask based on geosynchronous Earth orbit (GEO) and low Earth orbit (LEO) sensors, the positive detection rate over snow and ice surfaces increased from around 36% to 65% while the false detection rate dropped from 50% to 10% for observations of January 2016 and 2017. The improvement in July is less substantial due to relatively better performance in the current algorithm. The new algorithm is applicable for all snow and ice surfaces including Antarctic, sea ice, high-latitude snow, and high-altitude glacier regions. This method is less reliable when clouds are optically thin or below 3km because the sensitivity is low in oxygen band ratios for these cases. © 2020 Author(s)."
"57209747979;7004490499;7101723095;","Effect of Clouds on the Diurnal Evolution of the Atmospheric Boundary-Layer Height Over a Tropical Coastal Station",2020,"10.1007/s10546-019-00497-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078114639&doi=10.1007%2fs10546-019-00497-6&partnerID=40&md5=2c6439c8fdb75125b88edf563ff3c140","The growth of the daytime convective atmospheric boundary layer, which plays a pivotal role in the vertical mixing and dispersal of water vapour and pollutants, is modulated by cloud radiative effects. Assessment of this cloud effect is sparse in any geographical region and non-existent over tropical coastal regions. We investigate the effect of clouds on the diurnal evolution of boundary-layer height over tropical coastal location Thumba (8.5°N, 77°E) during onshore and offshore flow using multi-year (2010–2016) microwave radiometer profiler observations. The boundary-layer height during both cloudy and clear-sky periods increases rapidly from 0800 LT (local time = UTC + 5.1 h) to attain a daytime peak around noon (400–1500 m). The seasonal mean noontime boundary layer height during cloudy periods is lower than that during clear-sky periods by > 900 m (> 400 m) when offshore (onshore) flow prevails during winter and pre-monsoon seasons. The forenoon growth rate of the boundary-layer height during clear-sky offshore flow is rapid (> 380 m h−1) compared to that during cloudy offshore (160 m h−1), clear-sky onshore (160–250 m h−1), and cloudy onshore (> 100 m h−1) flow. Effects of shortwave cloud radiative forcing and soil temperature on the noontime boundary-layer height and their interdependencies are presented. These observations reveal the contrasting and significant effect of clouds on the growth of the daytime boundary layer during onshore and offshore flow, and the coupled effects of cloud radiative forcing and soil temperature on boundary-layer height over tropical coastal regions, which provide essential constraints for evaluating model simulations. © 2020, Springer Nature B.V."
"57193321288;7003591311;56127067100;56028554400;57213705405;","Surface solar irradiance in continental shallow cumulus fields: Observations and large-eddy simulation",2020,"10.1175/JAS-D-19-0261.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082884242&doi=10.1175%2fJAS-D-19-0261.1&partnerID=40&md5=44d144d8a473626d11ecb11c91e3295d","This study examines shallow cumulus cloud fields and their surface shortwave radiative effects using large-eddy simulation (LES) along with observations across multiple days at the Atmospheric Radiation Measurement Southern Great Plains atmospheric observatory. Pronounced differences are found between probability density functions (PDFs) of downwelling surface solar irradiance derived from observations and LES one-dimensional (1D) online radiation calculations. The shape of the observed PDF is bimodal, which is only reproduced by offline three-dimensional (3D) radiative transfer calculations, demonstrating PDF bimodality as a 3D radiative signature of continental shallow cumuli. Local differences between 3D and 1D radiative transfer calculations of downwelling surface solar irradiance are, on average, larger than 150 W m22 on one afternoon. The differences are substantially reduced when spatially averaged over the LES domain and temporally averaged over the diurnal cycle, but systematic 3D biases ranging from 2 to 8 W m22 persist across different days. Covariations between the domain-averaged surface irradiance, framed as a surface cloud radiative effect, and the simulated cloud fraction are found to follow a consistent diurnal relationship, often exhibiting hysteresis. In contrast, observations show highly variable behavior. By subsampling the LES domain, it is shown that this is due to the limited sampling density of inherently 3D observations. These findings help to define observational requirements for detecting such relationships, provide valuable insight for evaluating weather and climate models against surface observations as they push to ever higher resolutions, and have important implications for future assessments of solar renewable energy potential. © 2020 American Meteorological Society."
"57190687421;6508063123;57204428015;","The short-term variability of aerosols and their impact on cloud properties and radiative effect over the Indo-Gangetic Plain",2020,"10.1016/j.apr.2019.12.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077391285&doi=10.1016%2fj.apr.2019.12.017&partnerID=40&md5=ca5d3757658e36e5458520fe99dd8354","Anthropogenic activities have been shown to have a significant effect on weather and hence climate. However, discerning them from various observations over a certain region including India has been a challenge due to the large role played by natural variability. We show that anthropogenic signals in terms of sub-weekly scale are quite significant (of the order of 20%) in aerosol loading over the Indo-Gangetic Plains. These, in turn, clouds become thinner and less reflective with weekly variations of aerosol, which indicate the possible effect of aerosol on clouds. In terms of changes to Short Wave (SW) and Long Wave (LW) radiation fluxes, we find that change in aerosol direct effect is larger during cloudy sky conditions than clear sky conditions showing that aerosol induced changes to dynamics and hence clouds are dominant factors. This is also manifested in changes to cloud macro physical properties such as cloud optical depth (COD), cloud top temperature (CTT), cloud top pressure (CTP) and liquid water path (LWP). The changes in clear-sky and all-sky top of the atmosphere aerosol direct radiative effect (DRE) and cloud radiative effect (CRE) using CERES derived fluxes were found to be ~7–10% different during weekends with respect to weekly means. Similarly, the change in longwave cloud radiative effect is double that of the shortwave CRE. © 2020 Turkish National Committee for Air Pollution Research and Control"
"57194420030;55351266200;56909327200;7401836526;","Statistically Steady State Large-Eddy Simulations Forced by an Idealized GCM: 1. Forcing Framework and Simulation Characteristics",2020,"10.1029/2019MS001814","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081085411&doi=10.1029%2f2019MS001814&partnerID=40&md5=16c0fe8c7dae57e6450aa6dd6519c70a","Using large-eddy simulations (LES) systematically has the potential to inform parameterizations of subgrid-scale processes in general circulation models (GCMs), such as turbulence, convection, and clouds. Here we show how LES can be run to simulate grid columns of GCMs to generate LES across a cross section of dynamical regimes. The LES setup approximately replicates the thermodynamic and water budgets in GCM grid columns. Resolved horizontal and vertical transports of heat and water and large-scale pressure gradients from the GCM are prescribed as forcing in the LES. The LES are forced with prescribed surface temperatures, but atmospheric temperature and moisture are free to adjust, reducing the imprinting of GCM fields on the LES. In both the GCM and LES, radiative transfer is treated in a unified but idealized manner (semigray atmosphere without water vapor feedback or cloud radiative effects). We show that the LES in this setup reaches statistically steady states without nudging to thermodynamic GCM profiles. The steady states provide training data for developing GCM parameterizations. The same LES setup also provides a good basis for studying the cloud response to global warming. ©2020. The Authors."
"7402645443;7006729790;7004325649;7003854810;7404150761;11240723300;","Monetizing the Value of Measurements of Equilibrium Climate Sensitivity Using the Social Cost of Carbon",2020,"10.1007/s10666-019-09662-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064259199&doi=10.1007%2fs10666-019-09662-0&partnerID=40&md5=17c0eea1c70757f86f44ae77558ab9cf","There has been much work on the value of learning about climate and the value of information regarding the climatic system. The present research moves beyond an abstract hypothesis about future learning and considers concrete Earth Observing Systems that could enhance knowledge of the climatic system and better inform decision makers. This study shows how real options theory in combination with the social cost of carbon may help to calculate the value of information regarding equilibrium climate sensitivity and estimate the relative advantages of two different Earth Observing Systems (EOSs) for learning about ECS. One system aims to improve measurements of decadal global temperature increase and another targets measurements of decadal change of global cloud radiative effect. The paper concludes that a new EOS that substantially reduces the uncertainty in cloud radiative effect would be expected to have more value than improving estimations of the global surface temperature alone. © 2019, Springer Nature Switzerland AG."
"36815705700;43561261500;7404653593;7004242319;","Simulations of Winter Arctic Clouds and Associated Radiation Fluxes Using Different Cloud Microphysics Schemes in the Polar WRF: Comparisons With CloudSat, CALIPSO, and CERES",2020,"10.1029/2019JD031413","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079364732&doi=10.1029%2f2019JD031413&partnerID=40&md5=8ccb1c5f61707c327c2d41148d463da5","Arctic cloud simulations of the polar-optimized version of the Weather Research and Forecasting model (Polar WRF) were compared with retrievals using the CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation measurements. For the period from 1 December 2015 to 31 January 2016, a series of 24- to 48-hr simulations initialized daily at 00 UTC were examined. In particular, two cloud microphysics schemes, the Morrison double moment and the WRF single-moment 6-class (WSM6), were tested. The modeled cloud top heights had a correlation coefficient (r) of 0.69–0.72 with those from satellite retrievals, and a mean bias of less than 400 m. For the mean ice water content profile and mixed-phase cloud occurrence, the Morrison scheme's clouds were in better agreement with satellite retrievals than the WSM6. However, the use of the Morrison scheme resulted in underestimates of outgoing longwave radiation by −11.7 W m−2 compared to satellite observations. The bias was reduced to −0.4 W m−2 with the WSM6 which produced a stronger precipitation rate (by 10%) resulting in a drier and less-cloudy atmosphere. This also leads to the 7-W m−2 mean difference in the surface downward longwave radiation (DLR) between the schemes, which is large enough to explain the spread of the Arctic DLR in the current climate models. However, as the temporal variation in DLR showed good agreement with ground observations (r: 0.68–0.92), it is concluded that the Polar WRF can be useful for studying cloud effects on the winter Arctic surface climate. ©2020. American Geophysical Union. All Rights Reserved."
"55366700000;6506152198;56482796700;24402359000;7003591311;","Anthropogenic Air Pollution Delays Marine Stratocumulus Breakup to Open Cells",2019,"10.1029/2019GL085412","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076152967&doi=10.1029%2f2019GL085412&partnerID=40&md5=7dc138191373a4d3546477dca9e7f2fe","Marine stratocumulus cloud (Sc) decks with high cloud fraction typically breakup when sufficient drizzle forms. Cloud breakup leads to a lower cloud radiative effect due to the lower cloud amount. Here we use realistic Lagrangian large eddy simulations along a 3-day trajectory, evaluated with satellite observations, to investigate the timing of Sc breakup in response to aerosol conditions. We show that the timing of the breakup is strongly modulated by the diurnal cycle and large-scale meteorology but varies systematically with the initial aerosol concentration: the more polluted the clouds, the later the breakup. This indicates that the cloud radiative effect via cloud cover adjustments is not saturated, in contrast to the effect of aerosol on cloud albedo at fixed cloudiness, which weakens with increasing aerosol levels. The results also show that the cloud radiative impact of anthropogenic aerosol is strongest far from its origin over land. ©2019. The Authors."
"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."
"56049520900;56384704800;57202299549;15755995900;25629055800;57211514968;","Impact of Nudging Strategy on the Climate Representativeness and Hindcast Skill of Constrained EAMv1 Simulations",2019,"10.1029/2019MS001831","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076162227&doi=10.1029%2f2019MS001831&partnerID=40&md5=f2bb4bcd0e5cb35023e6b4984a8c065a","Nudging is a simulation technique widely used in sensitivity studies and in the evaluation of atmosphere models. Care is needed in the experimental setup in order to achieve the desired constraint on the simulated atmospheric processes without introducing undue intervention. In this study, sensitivity experiments are conducted with the Energy Exascale Earth System Model (E3SM) Atmosphere Model Version 1 (EAMv1) to identify setups that can give results representative of the model's long-term climate and meanwhile reasonably capture characteristics of the observed meteorological conditions to facilitate the comparison of model results with measurements. We show that when the prescribed meteorological conditions are temporally interpolated to the model time to constrain EAM's horizontal winds at each time step, a nudged simulation can reproduce the characteristic evolution of the observed weather events (especially in middle and high latitudes) as well as the model's long-term climatology, although nudging also leads to nonnegligible regional changes in wind-driven aerosol emissions, low-level clouds in the stratocumulus regime, and cloud and precipitation near the maritime continent. Compared to its predecessor model used in an earlier study, EAMv1 is less sensitive to temperature nudging, although significant impacts on the cloud radiative effects still exist. EAMv1 remains very sensitive to humidity nudging. Constraining humidity substantially improves the correlation between the simulated and observed tropical precipitation but also leads to large changes in the long-term statistics of the simulated precipitation, clouds, and aerosol lifecycle. ©2019. The Authors."
"23666736500;25227357000;7102018821;36150977900;56898331700;57138743300;7403079681;","Modeling study of the impact of complex terrain on the surface energy and hydrology over the Tibetan Plateau",2019,"10.1007/s00382-019-04966-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072098915&doi=10.1007%2fs00382-019-04966-z&partnerID=40&md5=497dc68ab83a6d1aa403002264444db7","The long-term effects of complex terrain on solar energy distributions and surface hydrology over the Tibetan Plateau (TP) are investigated using the 4th version of the global Community Climate System Model (CCSM4) coupled with a 3-D radiative transfer (RT) parameterization. We examine the differences between the results from CCSM4 with the 3-D RT parameterization and the results from CCSM4 with the plane-parallel RT scheme. In January (winter), the net surface solar flux (FSNS) displays negative deviations over valleys and the north slopes of mountains, especially in the northern margin of the TP, as a result of the 3-D shadow effect. Positive deviations in FSNS in January are found over the south slopes of mountains and over mountain tops, where more solar flux is intercepted. The deviations in total cloud fraction and snow water equivalent (SWE) exhibit patterns opposite to that of FSNS. The SWE decreases due to the 3-D mountain effect in spring and the magnitude of this effect depends on the terrain elevations. The SWE is reduced by 1–17 mm over the TP in April, with the largest decrease in SWE at an elevation of 3.5–4.5 km. Negative deviations in precipitation are found throughout the year, except in May and December, and they follow the seasonal variations in the deviations in total cloud fraction. The total liquid runoff at 3.5–4.5 km elevation increases in April due to earlier (March) snowmelt caused by increased downward solar radiation. The possible deviations in surface energy and SWE over the TP, caused by plane-parallel assumption in most climate models may result in biases in the liquid runoff and the river water resources over the TP and downstream. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature."
"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."
"26422603100;7102953444;57194527119;6603941796;","Estimating Shortwave Clear-Sky Fluxes From Hourly Global Radiation Records by Quantile Regression",2019,"10.1029/2019EA000686","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071439216&doi=10.1029%2f2019EA000686&partnerID=40&md5=2ba36eee3e021d410d891175bfebc2d6","Estimates of radiative fluxes under cloud-free conditions (“clear-sky”) are required in many fields, from climatic analyses of solar transmission to estimates of solar energy potential for electricity generation. Ideally, these fluxes can be obtained directly from measurements of solar fluxes at the surface. However, common standard methods to identify clear-sky conditions require observations of both the total and the diffuse radiative fluxes at very high temporal resolution of minutes, which restricts these methods to a few, well-equipped sites. Here we propose a simple method to estimate clear-sky fluxes only from typically available global radiation measurements (Rsd) at (half-)hourly resolution. Plotting a monthly sample of observed Rsd against the corresponding incoming solar radiation at the top of atmosphere (potential solar radiation) reveals a typical triangle shape with clear-sky conditions forming a distinct, linear slope in the upper range of observations. This upper slope can be understood as the fractional transmission of solar radiation representative for cloud-free conditions of the sample period. We estimate this upper slope through quantile regression. We employ data of 42 stations of the worldwide Baseline Surface Radiation Network to compare our monthly estimates with the standard clear-sky identification method developed by Long and Ackerman (2000, https://doi.org/10.1029/2000JD900077). We find very good agreement of the derived fractional solar transmission (R2 = 0.73) across sites. These results thus provide confidence in applying the proposed method to the larger set of global radiation measurements to obtain further observational constraints on clear-sky fluxes and cloud radiative effects. ©2019. The Authors."
"57193321288;57201653063;7003784786;7004942632;6603735878;7004028051;26659013400;","Shortwave spectral radiative signatures and their physical controls",2019,"10.1175/JCLI-D-18-0815.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068163449&doi=10.1175%2fJCLI-D-18-0815.1&partnerID=40&md5=b98b2b417c4e831e49e7da33dbcec40f","The spectrum of reflected solar radiation emerging at the top of the atmosphere is rich with Earth system information. To identify spectral signatures in the reflected solar radiation and directly relate them to the underlying physical properties controlling their structure, over 90 000 solar reflectance spectra are computed over West Africa in 2010 using a fast radiation code employing the spectral characteristics of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). Cluster analysis applied to the computed spectra reveals spectral signatures related to distinct surface properties, and cloud regimes distinguished by their spectral shortwave cloud radiative effect (SWCRE). The cloud regimes exhibit a diverse variety of mean broadband SWCREs, and offer an alternative approach to define cloud type for SWCRE applications that does not require any prior assumptions. The direct link between spectral signatures and distinct physical properties extracted from clustering remains robust between spatial scales of 1, 20, and 240 km, and presents an excellent opportunity to understand the underlying properties controlling real spectral reflectance observations. Observed SCIAMACHY spectra are assigned to the calculated spectral clusters, showing that cloud regimes are most frequent during the active West African monsoon season of June–October in 2010, and all cloud regimes have a higher frequency of occurrence during the active monsoon season of 2003 compared with the inactive monsoon season of 2004. Overall, the distinct underlying physical properties controlling spectral signatures show great promise for monitoring evolution of the Earth system directly from solar spectral reflectance observations. © 2019 American Meteorological Society."
"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."
"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."
"57194589938;56498662800;7003495982;57202942954;","Shallow cumulus representation and its interaction with radiation and surface at the convection gray zone",2019,"10.1175/MWR-D-19-0030.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073888307&doi=10.1175%2fMWR-D-19-0030.1&partnerID=40&md5=f061c95e703ad7033a67afba3eebd3b1","This study presents a systematic analysis of convective parameterizations performance with interactive radiation, microphysics, and surface on an idealized day with shallow convection. To this end, we analyze a suite of mesoscale numerical experiments (i.e., with parameterized turbulence). In the first set, two different convection schemes represent shallow convection at a 9-km resolution. These experiments are then compared with model results omitting convective parameterizations at 9- and 3-km horizontal resolution (gray zone). Relevant in our approach is to compare the results against two simulations by different large-eddy simulation (LES) models. Results show that the mesoscale experiments, including the 3-km resolution, are unable to adequately represent the timing, intensity, height, and extension of the shallow cumulus field. The main differences with LES experiments are the following: a too late onset, too high cloud base, and a too early transport of moisture too high, overestimating the second cloud layer. Related to this, both convective parameterizations produce warm and dry biases of up to 2K and 2 g kg-1, respectively, in the cloud layer. This misrepresentation of the cloud dynamics leads to overestimated shortwave radiation variability, both spacewise and timewise. Domain-averaged shortwave radiation at the surface, however, compares satisfactorily with LES. The shortwave direct and diffuse partition is misrepresented by the convective parameterizations with an underestimation (overestimation) of diffuse (direct) radiation both locally and, by a relative 40% (10%), of the domain average. © 2019 American Meteorological Society."
"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."
"57195761025;35494722400;","Multiband Simulations of Multistream Polarimetric Microwave Radiances Over Aspherical Hydrometeors",2018,"10.1029/2018JD028769","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056730069&doi=10.1029%2f2018JD028769&partnerID=40&md5=6a13f8a27012c891ee1fb651f0d2464f","A numerical precision assessment and simulation results of the Unified Microwave Radiative Transfer (UMRT) model incorporating aspherical frozen hydrometeors based on the NASA Goddard Space Flight Center (NASA/GSFC) OpenSSP database are presented. It is shown that UMRT maintains unconditional numerical stability and computational efficiency for absorbing and scattering clouds. UMRT requires symmetry of the transition matrix for the discretized planar-stratified radiative transfer equation to realize numerically stable and accurate matrix operations as required by the discrete ordinate eigenanalysis method. UMRT has heretofore been restricted to spherical polydispersive hydrometeors. In this study, the necessary block-diagonal structure of the full Stokes matrix for randomly oriented OpenSSP aspherical hydrometeors is shown to be maintained, albeit with small asymmetric deviations, which introduce small asymmetric components into the transition matrix that are negligible for most remote sensing applications. An upper bound of the brightness temperature error calculated by neglecting the asymmetric components of the transition matrix under even extreme atmospheric conditions is shown to be small. Hence, the OpenSSP hydrometeor database can be reliably used within the UMRT model. Block-diagonal Stokes matrix elements along with other single-scattering hydrometeor parameters were subsequently used in radiative simulations of multistream dual-polarization radiances for a simulated hurricane event to demonstrate the inherent numerical stability and utility of the enhanced UMRT model. An intercomparison of computed upwelling radiances for a multiphase distribution of aspherical OpenSSP hydrometeors versus a mass-equivalent Mie hydrometeor polydispersion for key sensing frequencies from 10 to 874 GHz shows the considerable impact of complex (vs. simple spherical) hydrometeors on predicted microwave radiances. ©2018. American Geophysical Union. All Rights Reserved."
"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."
"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."
"24334289200;7004337213;","Assessment of aerosol radiative forcing with 1-D radiative transfer modeling in the U. S. South-East",2018,"10.3390/atmos9070271","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050239423&doi=10.3390%2fatmos9070271&partnerID=40&md5=c2647e7f19106b8d6a7d0324d98a9546","Aerosols and their radiative properties play an integral part in understanding Earth's climate. It is becoming increasingly common to examine aerosol's radiative impacts on a regional scale. The primary goal of this research is to explore the impacts of regional aerosol's forcing at the surface and top-of-atmosphere (TOA) in the south-eastern U.S. by using a 1-D radiative transfer model. By using test cases that are representative of conditions common to this region, an estimate of aerosol forcing can be compared to other results. Speciation data and aerosol layer analysis provide the basis for the modeling. Results indicate that the region experiences TOA cooling year-round, where the winter has TOA forcings between -2.8 and -5 W/m2, and the summer has forcings between -5 and -15 W/m2 for typical atmospheric conditions. Surface level forcing efficiencies are greater than those estimated for the TOA for all cases considered i.e., urban and non-urban background conditions. One potential implication of this research is that regional aerosol mixtures have effects that are not well captured in global climate model estimates, which has implications for a warming climate where all radiative inputs are not well characterized, thus increasing the ambiguity in determining regional climate impacts. © 2018 by the authors."
"56279208100;7006007679;","Assessing reanalysis quality with early sounders Nimbus-4 IRIS (1970) and Nimbus-6 HIRS (1975)",2018,"10.1016/j.asr.2018.04.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046754441&doi=10.1016%2fj.asr.2018.04.022&partnerID=40&md5=ce5079d41ec2adced578e142d0e99780","This paper revisits the data collected by early sounders Nimbus-4 IRIS (1970) and Nimbus-6 HIRS (1975), after recovery of ageing tapes by NASA GES DISC. New quality controls are proposed to screen out erroneous or suspicious mission data, based on instrument health status data records and other inspection of the data. Radiative transfer coefficients are derived for the fast computation of clear-sky radiative transfer simulations. Atmospheric profiles from ERA-40 and ERA-20C reanalyses are used in input. These spatio-temporally complete datasets are interpolated to each sounding location, using the closest estimate in time. A modern cloud detection method derived for current hyperspectral sounders is applied to IRIS and yields maps of cloud cover that are in line with current knowledge of cloud climatology. For clear scenes, the standard deviation of brightness temperature differences between IRIS observations and simulations from ERA-20C is around 1 K for the lower-peaking temperature channels of the 15 μm CO 2 band, and lower than 1 K for simulations from ERA-40. The IRIS and HIRS instrumental data records are projected in a common sub-space to alleviate issues with different field-of-view resolutions and spectral resolutions. A proxy cloud detection scheme screens out clouds in the same manner in both data records. Considering the month of August, common to both missions, a detailed analysis of the departures from observations suggests that ERA-40 suffers from spurious tropospheric warming, possibly caused by changes in the observation input during the 1970s including a known error in ERA-40 radiance assimilation bias correction. This result, confirmed by considering a climate model integration, demonstrates that it is possible to exploit early sounder data records to derive detailed insight from reanalyses, such as attempting to qualify separately random and systematic errors in reanalyses, even at times when few other independent observation data are available. © 2018"
"56598005900;8380252900;12645277800;43061335300;57203006609;36486362800;","Top-of-atmosphere shortwave anisotropy over liquid clouds: Sensitivity to clouds'microphysical structure and cloud-topped moisture",2018,"10.3390/atmos9070256","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050245512&doi=10.3390%2fatmos9070256&partnerID=40&md5=ece7b64ec0e8feb4d138d167581d3d07","We investigated whether Top-of-Atmosphere Shortwave (TOA SW) anisotropy-essential to convert satellite-based instantaneous TOA SW radiance measurements into TOA SW fluxes-is sensitive to cloud-top effective radii and cloud-topped water vapor. Using several years of CERES SSF Edition 4 data-filtered for overcast, horizontally homogeneous, low-level and single-layer clouds of cloud optical thickness 10-as well as broadband radiative transfer simulations, we built refined empirical Angular Distribution Models (ADMs). The ADMs showed that anisotropy fluctuated particularly around the cloud bow and cloud glory (up to 2.9-8.0%) for various effective radii and at highest and lowest viewing zenith angles under varying amounts of cloud-topped moisture (up to 1.3-6.4%). As a result, flux estimates from refined ADMs differed from CERES estimates by up to 20 W m-2 at particular combinations of viewing and illumination geometry. Applied to CERES cross-track observation of January and July 2007-utilized to generate global radiation budget climatologies for benchmark comparisons with global climate models-we found that such differences between refined and CERES ADMs introduced large-scale biases of 1-2W m-2 and on regional levels of up to 10 W m-2. Such biases could be attributed in part to low cloud-top effective radii (about 8μm) and low cloud-topped water vapor (1.7 kg m-2) and in part to an inopportune correlation of viewing and illumination conditions with temporally varying effective radii and cloud-topped moisture, which failed to compensate towards vanishing flux bias. This work may help avoid sampling biases due to discrepancies between individual samples and the median cloud-top effective radii and cloud-top moisture conditions represented in current ADMs. © 2018 by the authors."
"57204515722;6603943978;56707316400;37021162700;56780023600;56271306100;8403728600;7005661275;8403728700;16064490100;","A long-term time series of global and diffuse photosynthetically active radiation in the Mediterranean: Interannual variability and cloud effects",2018,"10.5194/acp-18-7985-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048349025&doi=10.5194%2facp-18-7985-2018&partnerID=40&md5=f1e474476878ffd1cc84ce6583b35f33","Measurements of global and diffuse photosynthetically active radiation (PAR) have been carried out on the island of Lampedusa, in the central Mediterranean Sea, since 2002. PAR is derived from observations made with multifilter rotating shadowband radiometers (MFRSRs) by comparison with a freshly calibrated PAR sensor and by relying on the on-site Langley plots. In this way, a long-term calibrated record covering the period 2002-2016 is obtained and is presented in this work. The monthly mean global PAR peaks in June, with about 160Wm-2, while the diffuse PAR reaches 60Wm-2 in spring or summer. The global PAR displays a clear annual cycle with a semi amplitude of about 52Wm-2. The diffuse PAR annual cycle has a semi amplitude of about 12Wm-2. A simple method to retrieve the cloud-free PAR global and diffuse irradiances in days characterized by partly cloudy conditions has been implemented and applied to the dataset. This method allows retrieval of the cloud-free evolution of PAR and calculation of the cloud radiative effect, CRE, for downwelling PAR. The cloud-free monthly mean global PAR reaches 175Wm-2 in summer, while the diffuse PAR peaks at about 40Wm-2. The cloud radiative effect, CRE, on global and diffuse PAR is calculated as the difference between all-sky and cloud-free measurements. The annual average CRE is about -14.7Wm-2 for the global PAR and C8.1Wm-2 for the diffuse PAR. The smallest CRE is observed in July, due to the high cloud-free condition frequency. Maxima (negative for the global, and positive for the diffuse component) occur in March-April and in October, due to the combination of elevated PAR irradiances and high occurrence of cloudy conditions. Summer clouds appear to be characterized by a low frequency of occurrence, low altitude, and low optical thickness, possibly linked to the peculiar marine boundary layer structure. These properties also contribute to produce small radiative effects on PAR in summer. The cloud radiative effect has been deseasonalized to remove the influence of annual irradiance variations. The monthly mean normalized CRE for global PAR can be well represented by a multi-linear regression with respect to monthly cloud fraction, cloud top pressure, and cloud optical thickness, as determined from satellite MODIS observations. The behaviour of the normalized CRE for diffuse PAR can not be satisfactorily described by a simple multi-linear model with respect to the cloud properties, due to its nonlinear dependency, in particular on the cloud optical depth. The analysis suggests that about 77% of the global PAR interannual variability may be ascribed to cloud variability in winter. © Author(s) 2018."
"6602122304;","Characterization of Mixed-Phase Clouds: Contributions From the Field Campaigns and Ground Based Networks",2018,"10.1016/B978-0-12-810549-8.00005-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041197259&doi=10.1016%2fB978-0-12-810549-8.00005-2&partnerID=40&md5=4556cf10ef32d042f338e04f8cc20d30","Clouds and their associated microphysical processes regulate the atmospheric radiative transfer and the hydrological cycle. Mixed-phase clouds are an important component of the Earth cloud system, and their radiative effects are dependent on water phase partitioning. These clouds present particular challenges for observations and modeling, and their accurate representation in numerical models is essential for weather and climate simulations. The physical properties of mixed-phase clouds are derived mainly from aircraft observations, ground-based monitoring networks such as Atmospheric Radiation Measurement (ARM) Program and Cloudnet, and from satellites equipped with remote sensing instruments. This chapter presents a perspective on the main field experiments and ground-based networks during the last decades that resulted in improved characterization of mixed-phase clouds. © 2018 Elsevier Inc. All rights reserved."
"7004866567;6602458644;","Atmospheric soundings from hyperspectral satellite observations",2017,"10.1016/B978-0-12-409548-9.10384-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073390825&doi=10.1016%2fB978-0-12-409548-9.10384-7&partnerID=40&md5=d4b01b0416c8793b434a2a3f3360c0cd","This article provides an overview of the state of the art in atmospheric sounding theory, with a focus on the problematic aspects-mainly nonlinearity and rank deficiency-characterizing the practical implementation of a thermal inverse method. In this respect, this work proposes few guidelines aiming at indicating some possible steps that future missions and retrieval development efforts may want to consider, in order to maximize the future use of hyperspectral data for improved weather and climate applications. © 2018 Elsevier Inc. All rights reserved."
"56892889800;7501757094;","An effective approach to evaluate GCM simulated diurnal variation of clouds",2016,"10.1002/2016GL070446","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995378465&doi=10.1002%2f2016GL070446&partnerID=40&md5=fd0a7ed523e708fddafcf6b77deebc04","Cloud radiative effects strongly depend on diurnal variations of insolation and cloud radiative properties. In general circulation models (GCMs), even when the daily-mean cloud properties agree with observations, errors in cloud diurnal cycle can still significantly impact the shortwave radiation and induce model biases. However, this aspect is overlooked in GCM evaluation and intercomparison programs (e.g., Coupled Model Intercomparison Project Phase 5 (CMIP5)), which mainly consider the daily-mean cloud fraction. This study presents a simple approach of using a diagnostic parameter, the “effective-daytime cloud fraction” which accounts for the concurrent variation of clouds and insolation, to reveal GCM biases in cloud diurnal variations. The usefulness of the approach is illustrated by the significant biases of cloud diurnal cycle in the Modern-Era Retrospective analysis for Research and Applications (MERRA) reanalysis when compared with that in the International Satellite Cloud Climatology Project (ISCCP) data. It is thus suggested that the parameter be included as one of the GCM diagnostics for evaluating cloud diurnal cycle in model intercomparisons. ©2016. American Geophysical Union. All Rights Reserved."
"57190872506;","A new diagram of Earth’s global energy budget",2016,"10.1007/s40328-015-0138-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983685300&doi=10.1007%2fs40328-015-0138-0&partnerID=40&md5=30667a80c605a92815c2d92f71ae79d1","Abstract: A new global mean energy budget diagram is offered for discussion and further examination. The main motivation for creating this figure was the observation that a quasi-discrete flux quantity structure seems to appear behind the best published energy budget data. This structure underneath the observed global energy flow system might represent an idealized, hypothetic normal (steady) state onto which the actual climatic regimes and their changes can be projected. The unit of the all-sky structure is the value of the flux element called longwave cloud radiative effect (LWCRE), termed also the greenhouse effect of clouds; under prevailing average conditions, it turns out to be numerically equal to the all-sky surface transmitted irradiance, ST(all). There is also a clear-sky structure, as reported in earlier studies, where the unit of measure is one ST(clear). Three important features are independent of the discrete units: (a) the energies at the surface are equal to the total energy at top-of-atmosphere plus one LWCRE; (b) the energies in the atmosphere are equal to the energy at the surface plus two LWCRE; (c) the shortwave (SW) radiation absorbed by the surface is equal to the longwave (LW) energy in the all-sky greenhouse effect. The aim of our study is to present the system as it reveals itself in the data; theoretical explanation is out of our recent scope. Graphical Abstract: [InlineMediaObject not available: see fulltext.] © 2015, Akadémiai Kiadó."
"37027011900;6603925960;7102410621;57207507108;30667558200;35203328900;6507495053;8669401600;","An EarthCARE/ATLID simulator to evaluate cloud description in climate models",2015,"10.1002/2015JD023919.","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029233955&doi=10.1002%2f2015JD023919.&partnerID=40&md5=a841e2f926210712fe99bf7f708280df","Clouds still remain the largest source of uncertainty in model-based predictions of future climate; thus, the description of the clouds in climate models needs to be evaluated. In particular, the cloud detailed vertical distribution that impacts directly the cloud radiative effect needs to be evaluated. Active satellite sensors directly measure the cloud vertical distribution with high accuracy; their observations should be used for model evaluation together with a satellite simulator in order to allow fair comparison between models and observations. The next cloud lidar in space, EarthCARE/ATmospheric LIDar (ATLID), is planned for launch in 2018, while the current spaceborne cloud lidar CALIPSO/CALIOP is expected to stop collecting data within the next coming years. Here we describe the characteristics of the ATLID on board the EarthCARE satellite (spatial resolution, signal-to-noise ratio, wavelength, field of view, pulse repetition frequency, orbit, and high-spectral resolution lidar) that need to be taken into account to build a Cloud Feedback Model Intercomparison Project Observation Simulator Package (COSP)/ATLID simulator. We then present the COSP/ATLID simulator, and the low-, middle-, high-level cloud covers it produces, as well as the zonal mean cloud fraction profiles and the height-intensity histograms that are simulated by COSP/ATLID when overflying an atmosphere predicted by LMDZ5 global circulation model. Finally, we compare the clouds simulated by COSP/ATLID with those simulated by COSP/CALIPSO when overflying the same atmosphere. As the main differences between ATLID and CALIOP are taken into account in the simulators, the differences between COSP/ATLID and COSP/CALIPSO cloud covers are less than 1% in nighttime conditions. © 2015. American Geophysical Union."
"22939192200;56224155200;36118090300;","Examinations of cloud variability and future change in the coupled model intercomparison project phase 3 simulations",2014,"10.1007/s13143-014-0038-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957441921&doi=10.1007%2fs13143-014-0038-1&partnerID=40&md5=bb1cea51be0798503f9df0e463992d32","Low-level cloud variability is critical to the radiation balance of Earth due to its wide spatial coverage. Using the adjusted International Satellite Cloud Climatology Project (ISCCP) observations of Clement et al. (2009), and the Coupled Model Intercomparison Project Phase 3 (CMIP3) model simulations, this study examines the observed and the simulated low-cloud variations and their relationships with large-scale environmental variables. From the observational analysis, significant correlations are found between low clouds and those of sea surface temperature (SST), lower tropospheric stability (LTS), and sea level pressure (SLP) over tropical marine areas of low cloud prevailing regions during most of the year. Increase of SST coincides with the reduction of LTS and increased vertical motion, which tends to reduce low-level clouds in subtropical oceans. Among the 14 models investigated, CGCM3 and HadGEM1 exhibit more realistic representation of the observed relationship between low-level clouds and large-scale environments. In future climate projection, these two models show a good agreement in the reduction of low-cloud throughout much of the global oceans in response to greenhouse gas forcing, suggesting a positive low-cloud feedback in a climate change context. © 2014, Korean Meteorological Society and Springer Science+Business Media Dordrecht."
"7005642066;","Variation in radiative contribution by clouds to downward longwave flux",2014,"10.2151/jmsj.2014-A08","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910013140&doi=10.2151%2fjmsj.2014-A08&partnerID=40&md5=c36ae6eb4756256af25d92386ef0fd4a","Clouds strongly influence downward longwave radiative flux and affect the radiation budget at the surface. We evaluated the cloud radiative effect in both absolute and relative terms on downward longwave radiation at the surface; we considered variations in the cloud radiative effect with changes in cloud amount, precipitable water, and cloud base height, as measured by eight stations of the Baseline Surface Radiation Network. The downward longwave radiation predicted by a radiative transfer model agreed well with observations. The cloud radiative forcing and contribution ranged from –21 to 92 W m–2 and from –6 % to 38 %, respectively. The cloud effect shows a positive correlation to the shortwave diffusivity index (an index of cloud amount) and a negative correlation to precipitable water amount. The absolute effect values are small, depending on site conditions, but the relative effect values are larger under dry conditions than under humid conditions. Under humid conditions, the effect of the shortwave diffusivity index is very small. Under dry and cold conditions, such as those found in polar regions, negative values of cloud radiative contribution appear frequently because clouds absorb the emissions from temperature inversion layers. In comparison with prior research that used the A-Train satellite product, the present study shows a wider distribution and a larger maximum value for cloud forcing from amount of water vapor. Cloud effect has a roughly negative relationship with cloud base height, but a positive correlation with cloud base height occurs under low clouds at Tateno, which is located on the Pacific Ocean side of Japan. This correlation is because of the unusual relationship between cloud base height and cloud effect at Tateno during the summer and winter seasons. These results describe small-scale and near-surface variations in cloud effect, which are difficult to detect by satellite measurements. © 2014, Meteorological Society of Japan."
"7005435915;6602494687;","Russian investigations in the field of atmospheric radiation in 2007-2010",2013,"10.1134/S000143381301009X","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874298483&doi=10.1134%2fS000143381301009X&partnerID=40&md5=b1af46aa4199552210d105c792e09015","A short survey prepared by the Russian Commission on Atmospheric Radiation contains the most significant results of works in the field of atmospheric-radiation studies performed in 2007-2010. It is part of the Russian National Report on Meteorology and Atmospheric Sciences prepared for the International Association on Meteorology and Atmospheric Sciences (IAMAS). During this period, the Russian Commission on Atmospheric Radiation, jointly with concerned departments and organizations, ran the conference ""Physics and Education,"" dedicated to the 75th anniversary of the Department of Physics at St. Petersburg State University (2007); the International Symposium of CIS Countries ""Atmospheric Radiation and Dynamics"" (2009); and the 5th International Conference ""Atmospheric Physics, Climate, and Environment"" (2010). At the conferences, central problems in modern atmosphere physics were discussed: radiative transfer and atmospheric optics; greenhouse gases, clouds, and aerosols; remote methods of measurements; and new measurement data. This survey presents five directions covering the whole spectrum of investigations performed in the field of atmospheric radiation. © 2013 Pleiades Publishing, Ltd."
"15070481300;36951202700;55957072000;55957567300;55957853400;55279905600;","Comparison of ground techniques used to estimate cloud cover in Florianópolis, southern Brazil",2013,"10.22564/rbgf.v31i1.248","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889865038&doi=10.22564%2frbgf.v31i1.248&partnerID=40&md5=14cfbbd07aef27f4ae13bf80abebab64","Cloud cover is a key feature in Earth images acquired from space. Cloud cover data play a significant role in the weather forecast and climate knowledge, as well as in several human activities. Several studies have been conducted to establish a methodology and experimental setup in order to acquire reliable cloud cover data from remote sense observations performed on the surface. This research aimed at comparing ground data acquired by different systems for the same atmospheric scenario regarding cloud cover. Solar radiation data and sky images acquired at SONDA station located in Florianópolis, in 2002, were used to evaluate cloud cover. Also, cloud cover data collected at the international airport meteorological station distant 7,700 m from the SONDA station were used. This work compares these two sets of data acquired for sky scenarios with only one type of cloud. The results show good agreement in clear and completely overcast sky conditions. Future studies using longer time series will be developed in order to evaluate the influence of seasonal variability and atmospheric scenarios with several cloud types (low, medium and high clouds)."
"13403754000;7006614696;7007021059;7004379124;","Analysis of cloud properties associated with tropical convection in climate models and satellite data",2012,"10.2151/jmsj.2012-504","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870478967&doi=10.2151%2fjmsj.2012-504&partnerID=40&md5=573b1ea6a3eb37fd97902247ae44d23d","Cloud properties associated with tropical convection are analyzed for 11 models participating in Cloud Feedback Model Intercomparison Project Phase 1 (CFMIP1) in comparison with International Satellite Cloud Climatology Project (ISCCP) and other satellite observations and reanalysis datasets. Cloud properties are analyzed for different regimes of large-scale circulation field sorted by monthly mean of pressure coordinated vertical velocity at 500 hPa as an index of large-scale circulation. The present analysis is focused on warm oceanic regions with sea surface temperatures above 27°C where convection is active. The warm oceanic regions cover the vertical motion regimes ranging from strong ascent to weak descent. The ISCCP simulator outputs are used to evaluate cloud properties in the models. Cloud amount of optically thick high-clouds with optical thicknesses (τ) ≧ 3.6 and cloud-top pressure (CTP) ≦ 440 hPa is overestimated in the strong ascent regime while that of optically thin high-clouds with τ < 3.6 is underestimated for all the regimes. Cloud amount of optically thick low-clouds with CTP ≧ 680 hPa is overestimated in the weak vertical motion regime as well in some models. The relevance of cloud amount bias to cloud radiative effect bias is discussed. Observations show that optically thick clouds in the strong ascent regime often have tops around 180-310 hPa. In many models, the cloud top often reaches higher altitude compared to the observations. The tendency can especially be seen in the models adopting the moisture accumulation type scheme presumably due to excessively deep convection. Comparison of upward motion strength among the models and reanalyses suggests that cumulus parameterization performs better when entrainment rate is varied with large-scale environmental fields to reduce the convection deepness where necessary. © 2012, Meteorological Society of Japan."
"7405361965;7006581229;","Torrential rainfall responses to vertical wind shear, radiation and ice clouds: A rainfall partitioning analysis based on surface rainfall budget",2012,"10.1016/j.atmosres.2011.12.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84862828168&doi=10.1016%2fj.atmosres.2011.12.015&partnerID=40&md5=f5b6aab84b4c2c92a9136223035d9fac","The effects of vertical wind shear, radiation and ice clouds on the torrential rainfall event over Jinan, China during July 2007 are investigated through a rainfall partitioning analysis based on surface rainfall budget. All experiments are integrated with an imposed large-scale vertical velocity and zonal wind from the National Centers for Environmental Prediction (NCEP)/Global Data Assimilation System (GDAS), while vertical wind shear, cloud radiative effects, cloud-radiation interaction and ice clouds are, respectively, suppressed in the sensitivity experiments. The largest change in rainfall contribution from the rainfall with local atmospheric drying, water vapor divergence, and hydrometeor loss/convergence (TfM) caused by the exclusion of vertical wind shear is a decrease associated with the shrink of rainfall area and the decrease in decrease in hydrometeor loss/convergence. The largest change in rainfall contribution from the rainfall with local atmospheric drying, water vapor convergence, and hydrometeor loss/convergence (TFM) caused by the exclusion of ice clouds is an increase associated with the expansion of rainfall area and the enhancements in all rainfall processes. The exclusion of vertical wind shear also causes the increase in rainfall contribution from the rainfall with local atmospheric moistening, water vapor convergence, and hydrometeor loss/convergence (tFM), but the increase is weaker than the decrease in rainfall contribution from TfM. The rainfall contributions from the other rainfall types are less sensitive to these effects than those from the three rainfall types. The cloud radiative effects on rainfall contributions from all rainfall types are weaker than the effects of vertical wind shear and ice clouds. © 2012 Elsevier B.V."
"6602650107;36788535600;45761444600;6603022543;","Cloud effective transmittance at two sites of the Atacama Desert, Chile",2011,"10.1029/2011JD015905","https://www.scopus.com/inward/record.uri?eid=2-s2.0-80055063274&doi=10.1029%2f2011JD015905&partnerID=40&md5=84d12f5212f46b2f6a9020805f52854a","Broadband overcast cloud effective transmittance was determined at Arica (18.47S, 70.31°W, 20 m above sea level (asl)) and Poconchile (18.45°S, 70.07°W, 560 m asl), Atacama Desert, northern Chile, from 10 min averaged pyranometer measurements of total solar irradiance (ToSI) and ultraviolet solar irradiance (UVSI) during the period 2002-2005. The predominant cloud type is marine stratocumulus, characteristic of the southeastern Pacific tropical environment. The region's very regular climate conditions, characterized by overcast mornings and cloudless afternoons, allow the application of an empirical method to determine the expected clear-sky irradiance during cloudy mornings. The cloud effective transmittance (CET) is determined as the ratio of the measured cloudy-sky irradiance over the expected clear-sky irradiance. CET
The occurrence of events with increased and decreased integrated water vapor (IWV) at the Arctic site Ny-Ålesund, their relation to cloud properties, and the surface cloud radiative effect (CRE) is investigated. For this study, we used almost 2.5 years (from June 2016 to October 2018) of ground-based cloud observations processed with the Cloudnet algorithm, IWV from a microwave radiometer (MWR), long-Term radiosonde observations, and backward trajectories FLEXTRA. Moist and dry anomalies were found to be associated with North Atlantic flows and air transport within the Arctic region, respectively. The amount of water vapor is often correlated to cloud occurrence, presence of cloud liquid water, and liquid water path (LWP) and ice water path (IWP). In turn, changes in the cloud properties cause differences in surface CRE. During dry anomalies, in autumn, winter, and spring, the mean net surface CRE was lower by 2-37 W m-2 with respect to normal conditions, while in summer the cloud-related surface cooling was reduced by 49 W m-2. In contrast, under moist conditions in summer the mean net surface CRE becomes more negative by 25 W m-2, while in other seasons the mean net surface CRE was increased by 5-37 W m-2. Trends in the occurrence of dry and moist anomalies were analyzed based on a 25-year radiosonde database. Dry anomalies have become less frequent, with rates for different seasons ranging from -12.8 % per decade to -4 % per decade, while the occurrence of moist events has increased at rates from 2.8 % per decade to 6.4 % per decade.
. © 2020 BMJ Publishing Group. All rights reserved." "55155453000;56372917900;57195306464;35237179700;7005063241;6602412939;","The impact of planetary rotation rate on the reflectance and thermal emission spectrum of terrestrial exoplanets around sunlike stars",2020,"10.3847/1538-4357/ab83ec","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085290090&doi=10.3847%2f1538-4357%2fab83ec&partnerID=40&md5=0350626a6cb8737a23044e8dcc19ced2","Robust atmospheric and radiative transfer modeling will be required to properly interpret reflected-light and thermal emission spectra of terrestrial exoplanets. This will help break observational degeneracies between the numerous atmospheric, planetary, and stellar factors that drive planetary climate. Here, we simulate the climates of earthlike worlds around the Sun with increasingly slow rotation periods, from earthlike to fully Sun-synchronous, using the ROCKE-3D general circulation model. We then provide these results as input to the Spectral Planet Model, which employs the Spectral Mapping Atmospheric Radiative Transfer model to simulate the spectra of a planet as it would be observed from a future space-based telescope. We find that the primary observable effects of slowing planetary rotation rate are the altered cloud distributions, altitudes, and opacities that subsequently drive many changes to the spectra by altering the absorption band depths of biologically relevant gas species (e.g., H2O, O2, and O3).We also identify a potentially diagnostic feature of synchronously rotating worlds in mid-infrared H2O absorption/emission lines. © 2020. The American Astronomical Society. All rights reserved" "55653573700;6701689811;35577097300;7006837187;","Vertical profiles of submicron aerosol single scattering albedo over the Indian region immediately before monsoon onset and during its development: Research from the SWAAMI field campaign",2020,"10.5194/acp-20-4031-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082969524&doi=10.5194%2facp-20-4031-2020&partnerID=40&md5=c52fdfeca2dd67dd84665307fd3bfc60","Vertical structures of aerosol single scattering albedo (SSA), from near the surface through the free troposphere, have been estimated for the first time at distinct geographical locations over the Indian mainland and adjoining oceans, using in situ measurements of aerosol scattering and absorption coefficients aboard the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft during the South West Asian Aerosol Monsoon Interactions (SWAAMI) campaign from June to July 2016. These are used to examine the spatial variation of SSA profiles and also to characterize its transformation from just prior to the onset of Indian Summer Monsoon (June 2016) to its active phase (July 2016). Very strong aerosol absorption, with SSA values as low as 0.7, persisted in the lower altitudes (< 3 km) over the Indo-Gangetic Plains (IGP), prior to the monsoon onset, with a west-to-east gradient; lower values occurred in the north-western arid regions, peaking in the central IGP and somewhat decreasing towards the eastern end. During the active phase of the monsoon, the SSA is found to increase remarkably, indicating far less absorption. Nevertheless, significant aerosol absorption persisted in the lower and middle troposphere over the IGP. Inputting these SSA and extinction profiles into a radiative transfer model, we examined the effects of using height-resolved information in estimating atmospheric heating rates due to aerosols, over similar estimates made using a single columnar value. It was noted that use of a single SSA value leads to an underestimation (overestimation) of the heating rates over regions with low (high) SSA, emphasizing the importance of height-resolved information. Further, the use of realistic profiles showed significant heating of the atmosphere by submicron aerosol absorption at the middle troposphere, which may have strong implications for clouds and climate. © 2020 by ASME." "55914196800;57190380187;7102128820;7102425008;","Parametrizing cloud geometry and its application in a subgrid cloud-edge erosion scheme",2020,"10.1002/qj.3758","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086078108&doi=10.1002%2fqj.3758&partnerID=40&md5=8456845ad142f7a63ac9a5204c4fba7e","To represent the effects of unresolved cloud processes in numerical weather prediction and climate models, parametrizations of the subgrid properties of clouds are required. In this paper, we describe a method for specifying the “cloud-edge length” within a model grid-box, which is an important parameter for approximating the subgrid mixing of air at cloud boundaries. We begin by proposing three conceptual models that predict the cloud-edge length using the grid-box cloud fraction and a length-scale to be derived empirically. The conceptual models are then evaluated using a wide range of observations and cloud-resolving models. Based on the finding that the “effective cloud spacing” approach fits both these data best, we parametrize the effective cloud spacing as a function of pressure and model resolution. An application of this parametrization to the cloud erosion scheme in the ECMWF forecast model is then demonstrated. The effective cloud spacing approach is compared to the “effective cloud scale” approach and is shown to increase cloud fraction in stratocumulus regions, while decreasing cloud fraction in cumulus regions. These cloud changes have the overall effect of decreasing the error of the modelled top-of-atmosphere net short-wave irradiance when compared to CERES observations by around 3%. Additionally, the cloud-edge length is an important parameter for approximating subgrid radiative transfer and it is hoped that this parametrization will be useful to quantify the effect of representing 3D cloud radiative transfer in global models. © 2020 Royal Meteorological Society" "55503023100;55717441600;7404075868;55702592400;6603550074;","Radiometrically consistent climate fingerprinting using CRIS and AIRS hyperspectral observations",2020,"10.3390/rs12081291","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084589411&doi=10.3390%2frs12081291&partnerID=40&md5=49e0d7a821acd74316f2c9a3a4402357","We introduce a novel spectral fingerprinting scheme that can be used to derive long-term atmospheric temperature and water vapor anomalies from hyperspectral infrared sounders such as Cross-track Infrared Sounder (CrIS) and Atmospheric Infrared Sounder (AIRS). It is a challenging task to derive climate trends from real satellite observations due to the difficulty of carrying out accurate cloudy radiance simulations and constructing radiometrically consistent radiative kernels. To address these issues, we use a principal component based radiative transfer model (PCRTM) to perform multiple scattering calculations of clouds and a PCRTM-based physical retrieval algorithm to derive radiometrically consistent radiative kernels from real satellite observations. The capability of including the cloud scattering calculations in the retrieval process allows the establishment of a rigorous radiometric fitting to satellite-observed radiances under all-sky conditions. The fingerprinting solution is directly obtained via an inverse relationship between the atmospheric anomalies and the corresponding spatiotemporally averaged radiance anomalies. Since there is no need to perform Level 2 retrievals on each individual satellite footprint for the fingerprinting approach, it is much more computationally efficient than the traditional way of producing climate data records from spatiotemporally averaged Level 2 products. We have applied the spectral fingerprinting method to six years of CrIS and 16 years of AIRS data to derive long-term anomaly time series for atmospheric temperature and water vapor profiles. The CrIS and AIRS temperature and water vapor anomalies derived from our spectral fingerprinting method have been validated using results from the PCRTM-based physical retrieval algorithm and the AIRS operational retrieval algorithm, respectively. © 2020 by the authors." "57208782662;28367935500;6602999057;","The role of observed cloud-radiative anomalies for the dynamics of the North Atlantic Oscillation on synoptic time-scales",2020,"10.1002/qj.3768","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081667767&doi=10.1002%2fqj.3768&partnerID=40&md5=dafdded94bb8b043278869426344eee2","Clouds shape weather and climate by regulating the latent and radiative heating in the atmosphere. Recent work has demonstrated the importance of cloud-radiative effects (CRE) for the mean circulation of the extratropical atmosphere and its response to global warming. In contrast, little research has been done regarding the impact of CRE on internal variability. Here, we study how clouds and the North Atlantic Oscillation (NAO) couple on synoptic time-scales during Northern Hemisphere winter via CRE within the atmosphere (ACRE). A regression analysis based on 5-day mean data from CloudSat/CALIPSO, CERES and GERB satellite observations and ERA-Interim short-term forecast data reveals a robust dipole of high-level and low-level cloud-incidence anomalies during a positive NAO, with increased high-level cloud incidence along the storm track (near 45°N) and the subpolar Atlantic, and decreased high-level cloud incidence poleward and equatorward of this track. Opposite changes occur for low-level cloud incidence. The cloud anomalies lead to an anomalous column-mean heating from ACRE over the region of the Iceland low, and to a cooling over the region of the Azores high. To quantify the impact of the ACRE anomalies on the NAO, and to thereby test the hypothesis of a cloud-radiative feedback on the NAO persistence, we apply the surface pressure tendency equation for ERA-Interim short-term forecast data. The NAO-generated ACRE anomalies amplify the NAO-related surface pressure anomalies over the Azores high but have no area-averaged impact on the Iceland low. In contrast, diabatic processes as a whole, including latent heating and clear-sky radiation, strongly amplify the NAO-related surface pressure anomalies over both the Azores high and the Iceland low, and their impact is much more spatially coherent. This suggests that, while atmospheric cloud-radiative effects lead to an increase in NAO persistence on synoptic time-scales, their impact is relatively minor and much smaller than other diabatic processes. © 2020 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society." "18435176600;6601981008;6603468634;6602938973;47761439400;57214728331;57214729273;","A Sea Surface Temperature data record (2004–2012) from Meteosat Second Generation satellites",2020,"10.1016/j.rse.2020.111687","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078982447&doi=10.1016%2fj.rse.2020.111687&partnerID=40&md5=6dec2055f22824d6e0dd7f2a3018d2f7","The Ocean and Sea-Ice Satellite Application Facility (OSI-SAF) of the EUropean Organisation for the Exploitation of METeorological Satellites (EUMETSAT) has performed a reprocessing of Sea Surface Temperature (SST) from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard Meteosat Second Generation (MSG) archive (2004–2012). The retrieval method consists of a non-linear split-window algorithm and an algorithm correction relying on simulations of infrared brightness temperatures performed using atmospheric profiles of water vapour and temperature from a Numerical Weather Prediction model, and a radiative transfer model. The cloud mask used is the Climate SAF reprocessing of the MSG/SEVIRI archive which is consistent over the period considered. Atmospheric Saharan dust has a strong impact on the retrieved SST in the Atlantic and Mediterranean regions, they are taken into consideration through the computation of the Saharan Dust Index (SDI) which is then used to determine an empirical correction applied to SST. The reprocessing has benefited from the experience of the OSI SAF team in operational near real time processing of MSG/SEVIRI data, and the methods have been improved to provide a higher quality SST. The MSG/SEVIRI SST reprocessing dataset consists of hourly level 3 composites of sub-skin temperature projected onto a regular 0.05° grid over the region delimited by 60N,60S and 60W,60E. It has been thoroughly validated against drifting buoys and moored buoys measurements. Results of this validation have shown that the reprocessed data record is of significantly better quality than the OSI SAF operational processing (for instance the day-time robust standard deviation is 0.45 K for the operational processing and 0.35 K for the reprocessed dataset). The data record has been used to characterize the diurnal variability of SST over large temporal and spatial scales. © 2020 The Authors" "57216133573;8629713500;7401796996;7102423967;57200702127;56457152000;","Investigation of aerosol-cloud interactions under different absorptive aerosol regimes using Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) ground-based measurements",2020,"10.5194/acp-20-3483-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082576784&doi=10.5194%2facp-20-3483-2020&partnerID=40&md5=598ef7cbd2374981ea786a1421fa396f","The aerosol indirect effect on cloud microphysical and radiative properties is one of the largest uncertainties in climate simulations. In order to investigate the aerosol-cloud interactions, a total of 16 low-level stratus cloud cases under daytime coupled boundary-layer conditions are selected over the southern Great Plains (SGP) region of the United States. The physicochemical properties of aerosols and their impacts on cloud microphysical properties are examined using data collected from the Department of Energy Atmospheric Radiation Measurement (ARM) facility at the SGP site. The aerosol-cloud interaction index (ACIr) is used to quantify the aerosol impacts with respect to cloud-droplet effective radius. The mean value of ACIr calculated from all selected samples is 0.145±0.05 and ranges from 0.09 to 0.24 at a range of cloud liquid water paths (LWPs; LWPCombining double low line20-300 g m-2). The magnitude of ACIr decreases with an increasing LWP, which suggests a diminished cloud microphysical response to aerosol loading, presumably due to enhanced condensational growth processes and enlarged particle sizes. The impact of aerosols with different light-absorbing abilities on the sensitivity of cloud microphysical responses is also investigated. In the presence of weak light-absorbing aerosols, the low-level clouds feature a higher number concentration of cloud condensation nuclei (NCCN) and smaller effective radii (re), while the opposite is true for strong light-absorbing aerosols. Furthermore, the mean activation ratio of aerosols to CCN (NCCNĝˆ•Na) for weakly (strongly) absorbing aerosols is 0.54 (0.45), owing to the aerosol microphysical effects, particularly the different aerosol compositions inferred by their absorptive properties. In terms of the sensitivity of cloud-droplet number concentration (Nd) to NCCN, the fraction of CCN that converted to cloud droplets (Ndĝˆ•NCCN) for the weakly (strongly) absorptive regime is 0.69 (0.54). The measured ACIr values in the weakly absorptive regime are relatively higher, indicating that clouds have greater microphysical responses to aerosols, owing to the favorable thermodynamic condition. The reduced ACIr values in the strongly absorptive regime are due to the cloud-layer heating effect induced by strong light-absorbing aerosols. Consequently, we expect larger shortwave radiative cooling effects from clouds in the weakly absorptive regime than those in the strongly absorptive regime.. © 2020 BMJ Publishing Group. All rights reserved." "8670213100;57195505740;56983008100;57212017936;24778445700;6507681572;37111900500;15841350300;7102953444;6701796418;","Global dimming and brightening features during the first decade of the 21st cntury",2020,"10.3390/atmos11030308","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082175852&doi=10.3390%2fatmos11030308&partnerID=40&md5=0f3241c47124019510468dcd603d002c","Downward surface solar radiation (SSR) trends for the first decade of the 2000s were computed using a radiative transfer model and satellite and reanalysis input data and were validated against measurements from the reference global station networks Global Energy Balance Archive (GEBA) and Baseline Surface Radiation Network (BSRN). Under all-sky conditions, in spite of a somewhat patchy structure of global dimming and brightening (GDB), an overall dimming was found that is weaker in the Northern than in the Southern Hemisphere (-2.2 and -3.1 W m-2, respectively, over the 2001-2009 period). Dimming is observed over both land and ocean in the two hemispheres, but it is more remarkable over land areas of the Southern Hemisphere. The post-2000 dimming is found to have been primarily caused by clouds, and secondarily by aerosols, with total cloud cover contributing -1.4 W m-2 and aerosol optical thickness -.7 W m-2 to the global average dimming of -2.65 W m-2. The evaluation of the model-computed GDB against BSRN and GEBA measurements indicates a good agreement, with the same trends for 65% and 64% of the examined stations, respectively. The obtained model results are in line with other studies for specific world regions and confirm the occurrence of an overall solar dimming over the globe during the first decade of 21st century. This post-2000 dimming has succeeded the global brightening observed in the 1990s and points to possible impacts on the ongoing global warming and climate change. © 2020 by the authors." "22635081500;6603081424;56567382200;","An evaluation of clouds and radiation in a large-scale atmospheric model using a cloud vertical structure classification",2020,"10.5194/gmd-13-673-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081124922&doi=10.5194%2fgmd-13-673-2020&partnerID=40&md5=8a4ec0842b9474122b9835f0923a89ae","We revisit the concept of the cloud vertical structure (CVS) classes we have previously employed to classify the planet's cloudiness (Oreopoulos et al., 2017). The CVS classification reflects simple combinations of simultaneous cloud occurrence in the three standard layers traditionally used to separate low, middle, and high clouds and was applied to a dataset derived from active lidar and cloud radar observations. This classification is now introduced in an atmospheric global climate model, specifically a version of NASA's GEOS-5, in order to evaluate the realism of its cloudiness and of the radiative effects associated with the various CVS classes. Such classes can be defined in GEOS-5 thanks to a subcolumn cloud generator paired with the model's radiative transfer algorithm, and their associated radiative effects can be evaluated against observations. We find that the model produces 50 % more clear skies than observations in relative terms and produces isolated high clouds that are slightly less frequent than in observations, but optically thicker, yielding excessive planetary and surface cooling. Low clouds are also brighter than in observations, but underestimates of the frequency of occurrence (by ∼20 % in relative terms) help restore radiative agreement with observations. Overall the model better reproduces the longwave radiative effects of the various CVS classes because cloud vertical location is substantially constrained in the CVS framework. © 2020 Author(s)." "56682110000;23970271800;7003922583;","The sub-adiabatic model as a concept for evaluating the representation and radiative effects of low-level clouds in a high-resolution atmospheric model",2020,"10.5194/acp-20-303-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077971844&doi=10.5194%2facp-20-303-2020&partnerID=40&md5=dc4bfb3215b17aeb81c667e32eec726c","The realistic representation of low-level clouds, including their radiative effects, in atmospheric models remains challenging. A sensitivity study is presented to establish a conceptual approach for the evaluation of low-level clouds and their radiative impact in a highly resolved atmospheric model. Considering simulations for six case days, the analysis supports the notion that the properties of clouds more closely match the assumptions of the sub-adiabatic rather than the vertically homogeneous cloud model, suggesting its use as the basis for evaluation. For the considered cases, 95.7 % of the variance in cloud optical thickness is explained by the variance in the liquid water path, while the droplet number concentration and the sub-adiabatic fraction contribute only 3.5 % and 0.2 % to the total variance, respectively. A mean sub-adiabatic fraction of 0.45 is found, which exhibits strong inter-day variability. Applying a principal component analysis and subsequent varimax rotation to the considered set of nine properties, four dominating modes of variability are identified, which explain 97.7 % of the total variance. The first and second components correspond to the cloud base and top height, and to liquid water path, optical thickness, and cloud geometrical extent, respectively, while the cloud droplet number concentration and the sub-adiabatic fraction are the strongest contributors to the third and fourth components. Using idealized offline radiative transfer calculations, it is confirmed that the shortwave and longwave cloud radiative effects exhibit little sensitivity to the vertical structure of clouds. This reconfirms, based on an unprecedented large set of highly resolved vertical cloud profiles, that the cloud optical thickness and the cloud top and bottom heights are the main factors dominating the shortwave and longwave radiative effect of clouds and should be evaluated together with radiative fluxes using observations to attribute model deficiencies in the radiative fluxes to deficiencies in the representation of clouds. Considering the different representations of cloud microphysical processes in atmospheric models, the analysis has been further extended and the deviations between the radiative impact of the singleand double-moment schemes are assessed. Contrasting the shortwave cloud radiative effect obtained from the doublemoment scheme to that of a single-moment scheme, differences of about ∼ 40 Wm-2 and significant scatter are observed. The differences are attributable to a higher cloud albedo resulting from the high values of droplet number concentration in particular in the boundary layer predicted by the double-moment scheme, which reach median values of around ∼ 600 cm-3,. © 2020 Author(s)." "57207307943;6603613067;8397494800;57212021933;12806862100;6603452105;6701368631;8950640300;","Modelling the relationship between liquid water content and cloud droplet number concentration observed in low clouds in the summer Arctic and its radiative effects",2020,"10.5194/acp-20-29-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077562698&doi=10.5194%2facp-20-29-2020&partnerID=40&md5=388fbea45104392abf0a027a542488aa","Low clouds persist in the summer Arctic with important consequences for the radiation budget. In this study, we simulate the linear relationship between liquid water content (LWC) and cloud droplet number concentration (CDNC) observed during an aircraft campaign based out of Resolute Bay, Canada, conducted as part of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments study in July 2014. Using a singlecolumn model, we find that autoconversion can explain the observed linear relationship between LWC and CDNC. Of the three autoconversion schemes we examined, the scheme using continuous drizzle (Khairoutdinov and Kogan, 2000) appears to best reproduce the observed linearity in the tenuous cloud regime (Mauritsen et al., 2011), while a scheme with a threshold for rain (Liu and Daum, 2004) best reproduces the linearity at higher CDNC. An offline version of the radiative transfer model used in the Canadian Atmospheric Model version 4.3 is used to compare the radiative effects of the modelled and observed clouds. We find that there is no significant difference in the upward longwave cloud radiative effect at the top of the atmosphere from the three autoconversion schemes (p = 0.05) but that all three schemes differ at p = 0.05 from the calculations based on observations. In contrast, the downward longwave and shortwave cloud radiative effect at the surface for the Wood (2005b) and Khairoutdinov and Kogan (2000) schemes do not differ significantly (p = 0.05) from the observation-based radiative calculations, while the Liu and Daum (2004) scheme differs significantly from the observation-based calculation for the downward shortwave but not the downward longwave fluxes. © Author(s) 2020." "57219284671;35799889800;56920790500;56597778200;35069282600;57198373080;35772803100;23977685500;6701410329;7103353990;","Cloud_cci ATSR-2 and AATSR data set version 3: A 17-year climatology of global cloud and radiation properties",2020,"10.5194/essd-12-2121-2020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092047248&doi=10.5194%2fessd-12-2121-2020&partnerID=40&md5=8442c379bbc2ffde226e784b5809abe4","We present version 3 (V3) of the Cloud_cci Along-Track Scanning Radiometer (ATSR) and Advanced ATSR (AATSR) data set. The data set was created for the European Space Agency (ESA) Cloud_cci (Climate Change Initiative) programme. The cloud properties were retrieved from the second ATSR (ATSR-2) on board the second European Remote Sensing Satellite (ERS-2) spanning 1995-2003 and the AATSR on board Envisat, which spanned 2002-2012. The data are comprised of a comprehensive set of cloud properties: cloud top height, temperature, pressure, spectral albedo, cloud effective emissivity, effective radius, and optical thickness, alongside derived liquid and ice water path. Each retrieval is provided with its associated uncertainty. The cloud property retrievals are accompanied by high-resolution top- and bottom-of-atmosphere shortwave and longwave fluxes that have been derived from the retrieved cloud properties using a radiative transfer model. The fluxes were generated for all-sky and clear-sky conditions. V3 differs from the previous version 2 (V2) through development of the retrieval algorithm and attention to the consistency between the ATSR-2 and AATSR instruments. The cloud properties show improved accuracy in validation and better consistency between the two instruments, as demonstrated by a comparison of cloud mask and cloud height with co-located CALIPSO data. The cloud masking has improved significantly, particularly in its ability to detect clear pixels. The Kuiper Skill score has increased from 0.49 to 0.66. The cloud top height accuracy is relatively unchanged. The AATSR liquid water path was compared with the Multisensor Advanced Climatology of Liquid Water Path (MAC-LWP) in regions of stratocumulus cloud and shown to have very good agreement and improved consistency between ATSR-2 and AATSR instruments. The correlation with MAC-LWP increased from 0.4 to over 0.8 for these cloud regions. The flux products are compared with NASA Clouds and the Earth's Radiant Energy System (CERES) data, showing good agreement within the uncertainty. The new data set is well suited to a wide range of climate applications, such as comparison with climate models, investigation of trends in cloud properties, understanding aerosol cloud interactions, and providing contextual information for co-located ATSR-2/AATSR surface temperature and aerosol products. © 2020 Author(s)." "55851633600;26533129200;7102314226;6701729202;7003663305;57190852346;","Radiative Influence of Horizontally Oriented Ice Crystals over Summit, Greenland",2019,"10.1029/2018JD028963","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075433804&doi=10.1029%2f2018JD028963&partnerID=40&md5=7b5d65cedd998a3f431b0c6070f136a8","Ice crystals commonly adopt a horizontal orientation under certain aerodynamic and electrodynamic conditions that occur in the atmosphere. While the radiative impact of horizontally oriented ice crystals (HOIC) has been theoretically studied with respect to their impact on shortwave cloud albedo, the longwave impact remains unexplored. This work analyzes the occurrence of HOIC at Summit, Greenland, from July 2015 to June 2017. Using polarization lidar and ancillary atmospheric sensors, ice crystal orientations are identified and used to interpret cloud radiative impact on the surface radiation budget. We find HOIC occur in at least 25.6% of all ice-only column observations. We find that the shortwave impact of HOIC is to increase cloud radiative effect by approximately 22% for a given solar zenith angle. We also find that the longwave impact of HOIC compared to randomly oriented ice crystals are statistically different at the p < 0.01 significance level, increasing the surface radiative effect by approximately 8% for clouds with infrared optical depths < ~1. We suggest that the observed difference between the surface radiative effect for clouds containing randomly oriented ice crystals and HOIC may be due to enhanced scattering, but this hypothesis needs to be further explored with more detailed observations and modeling. ©2019. American Geophysical Union. All Rights Reserved." "24402359000;7003591311;6506152198;","Aerosol-Cloud Interactions in Trade Wind Cumulus Clouds and the Role of Vertical Wind Shear",2019,"10.1029/2019JD031073","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075429785&doi=10.1029%2f2019JD031073&partnerID=40&md5=f7fe1065b50319abe0e18c9b019bacbd","In shallow cumulus clouds, cloud deepening as a dynamical response to increased droplet number concentration has recently been shown to buffer the microphysical suppression of precipitation. In the current study, large eddy simulations with a two-moment bin microphysics model are employed to revisit this buffering and to investigate the role of vertical wind shear in aerosol-cloud interactions in trade wind cumuli. An idealized case is developed based on ship measurements and corresponding reanalysis data over the Sulu Sea in the Philippines in September 2012. A quasi-steady state is reached after roughly 25 – 35 hr for all six simulations performed (three different aerosol concentrations covering 35 – 230 cm−3, with/without vertical wind shear). All simulations show that the aerosol effect is buffered, to first order; increased aerosol results in deeper clouds, a reduced cloud fraction, and an increase in the shortwave cloud radiative effect. For the no-shear cases, positive aerosol perturbations result in a small increase in surface precipitation, while the opposite is true in the presence of vertical wind shear because of muted deepening. Analysis shows competing influences of vertical wind shear; enhanced cloud clustering protects clouds from evaporation and entrainment while tilting of clouds enhances evaporation. In spite of the small responses of surface precipitation to very large changes in aerosol, cloud size and spatial distributions and charge/discharge precipitation cycles differ significantly, expressing changes in the pathways to surface precipitation and a dynamical buffering of the system. ©2019. American Geophysical Union. All Rights Reserved." "57210951003;36701716800;","Aerosol and cloud radiative forcing over various hot spot regions in India",2019,"10.1016/j.asr.2019.07.028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071996656&doi=10.1016%2fj.asr.2019.07.028&partnerID=40&md5=e376e1129786ce379fa88f687b64c04d","Twelve years of NASA CERES (Clouds and Earth's Radiant Energy System) data have been used to examine the spatio-temporal variability of aerosol– and cloud– induced shortwave radiative forcing over selected hot spot regions in India. Four regions (northern semiarid – R1; monsoon trough – R2; densely populated urban – R3; and southern peninsula – R4) are selected with different surface characteristics and notable difference in meteorological and geographical features. The analysis shows that three out of the four regions (viz. R1, R2, and R3) experience high aerosol loading and forcing in the monsoon season followed by moderate forcing in pre-monsoon season. While all the seasons except the post-monsoon period show a positive linear relation between cloud optical depth and aerosol optical depth for all the regions, the post-monsoon season shows a negative relation. However, the relation between aerosol forcing and cloud forcing shows adequate non-linearity owing to the numerous factors that control cloud radiative effect. The estimated aerosol induced heating rate shows exponential decrease with height, but with high variability during each season. Irrespective of any region, the maximum heating rate is observed in the pre-monsoon season (2.86 ± 0.78, 2.49 ± 0.78, 1.89 ± 0.57, and 0.88 ± 0.28 K/day for R1, R2, R3, and R4, respectively). Plausible reasons for the variation in the above parameters are discussed. The results suggest that increased anthropogenic activities affect the thermodynamics and hence the dynamics through retention and exchange of heat, and it could affect the precipitation pattern adversely. © 2019 COSPAR" "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." "57209177753;6507605950;13006903300;","Homogeneity criteria from AVHRR information within IASI pixels in a numerical weather prediction context",2019,"10.5194/amt-12-3001-2019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066733042&doi=10.5194%2famt-12-3001-2019&partnerID=40&md5=445e5f76a6a79ef41a317357d9252724","This article focuses on the selection of satellite infrared IASI (Infrared Atmospheric Sounding Interferometer) observations in the global numerical weather prediction (NWP) system ARPEGE (Action de Recherche Petite Echelle Grande Echelle). The observation simulation is performed with the sophisticated radiative transfer model RTTOV-CLD, which takes into account the cloud scattering and the multilayer clouds from atmospheric profiles and cloud microphysical profiles (liquid water content, ice content and cloud fraction). The aim of this work is to select homogeneous scenes by using the information of the collocated Advanced Very High Resolution Radiometer (AVHRR) pixels inside each IASI field of view and to retain the most favourable cases for the assimilation of IASI infrared radiances. Two methods to select homogeneous scenes using homogeneity criteria already proposed in the literature were adapted: the criteria derived from Martinet et al. (2013) for cloudy sky selection in the French mesoscale model AROME (Applications of Research to Operations at MEsoscale) and the criteria from Eresmaa (2014) for clear-sky selection in the global model IFS (Integrated Forecasting System). A comparison between these methods reveals considerable differences, in both the method to compute the criteria and the statistical results. From this comparison a revised method representing a kind of compromise between the different tested methods is proposed and it uses the two infrared AVHRR channels to define the homogeneity criteria in the brightness temperature space. This revised method has a positive impact on the observation minus the simulation statistics, while retaining 36% of observations for the assimilation. It was then tested in the NWP system ARPEGE for the clear-sky assimilation. These criteria were added to the current data selection based on the McNally and Watts (2003) cloud detection scheme. It appears that the impact on analyses and forecasts is rather neutral. © Author(s) 2019." "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." "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." "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." "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." "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." "35313639700;7203073307;","Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia - Part 2: Modification of the weather system",2018,"10.5194/acp-18-11529-2018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051712294&doi=10.5194%2facp-18-11529-2018&partnerID=40&md5=405dd29d40dac1d22c64b7fd1c24ef02","An updated version of the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) was applied to quantify and investigate the full effects of dust on the meteorological field over East Asia during March and April 2012. The performances of the model in simulating the shortwave and longwave radiation, surface temperature, and precipitation over East Asia are improved by incorporating the effects of dust in the simulations. The radiative forcing induced by the direct radiative effect of dust is greater than that by the dust-enhanced cloud radiative effect. The indirect effects of dust result in a substantial increase in ice clouds at the middle to upper troposphere and a reduction in liquid clouds at the low to mid-troposphere. The radiative forcing combined with the redistribution of atmospheric water vapor results in an overall decrease in near-surface temperature and an increase in temperature at the middle to upper troposphere over East Asia, leading to an inhibition of atmospheric instability over most land areas, but an enhancement of atmospheric instability over south China. Upon considering the effects of dust, convective precipitation exhibits an inhibition over areas from central to east China and an enhancement over south China. Meanwhile, the locations of non-convective precipitation are shifted due to the perturbation of cloud water path. The total amount of precipitation over East Asia remains unchanged; however, the precipitation locations are shifted. The precipitation can be enhanced or inhibited by up to 20 % at particular areas. © Author(s) 2018." "55339081600;57205307947;35611334800;6602600408;","A Prospectus for Constraining Rapid Cloud Adjustments in General Circulation Models",2018,"10.1029/2017MS001153","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052840847&doi=10.1029%2f2017MS001153&partnerID=40&md5=60a1257b7125590884651e9624df7c92","Rapid cloud adjustments are an important component of the atmosphere's total response to increased CO2 concentrations. Unfortunately, scientific understanding of rapid shortwave cloud adjustments is rather poor. State-of-the-art 5th Coupled Model Intercomparison Project models showed large uncertainty in regard to rapid cloud adjustments. This study determines whether large-eddy simulations may, in principle, be used as a reference, thanks to their ability to resolve cloud dynamics and thermodynamics, to constrain rapid shortwave cloud adjustments in general circulation models. This is an open question since large-eddy models can only be run over limited domains, for a short period of time, and are influenced by boundary conditions. Using the Icosahedral Non-hydrostatic global climate model—Atmospheric component (ICON-A), we examine shortwave rapid cloud adjustments over central Europe, which is found to be representative of shortwave rapid cloud adjustments over Northern Hemispheric global continents in the 5th Coupled Model Intercomparison Project models. This work finds (i) a couple of days of simulation is sufficient to get a clear signal in the net top-of-atmosphere radiative balance to emerge after a 4xCO2 perturbation and (ii) use of present-day meteorological and CO2 concentrations for boundary conditions in global simulations is not an issue for short lead times, up to ∼36 hr. We also found that atmospheric processes influencing shortwave rapid cloud adjustments over central Europe are largely thermodynamically driven changes in local cloud dynamics and are rather independent of the synoptic-scale and circulation effects on short timescales (<2 days). These results imply that high-resolved large-eddy simulations over a limited area can be instructive for assessing and constraining global rapid cloud adjustments. ©2018. The Authors." "57194974081;","Climate impacts of particulate pollutants emitted from international shipping",2018,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053899051&partnerID=40&md5=a02994dc07e0b0b5688aaacc375abdad","International shipping represents a large sector for heavy fuel oil consumption and is an important source of particulate matter (PM) emissions and their precursors, including SO2. PM from international shipping emissions (ISE) could have significant cooling radiative effects on the Earth's climate system through direct (aerosol-radiation) and indirect (aerosol-cloud) interactions. To reduce the pollution and climate impacts of ISE, the International Maritime Organization (IMO) has set various emission caps on the sulfur content of marine fuel oil to be implemented in the future. Concawe commissioned MIT to conduct a modeling study using a state-of-the-art climate model, Community Earth System Model, to address the uncertainties that influence the estimation of cloud radiative effects of ISE. Several scenarios were simulated to quantify the impacts of the IMO's emission regulations on the radiative effects of ISEs. Also, the influence of naturally occurring dimethyl sulfide emissions on the cloud radiative effects of ISE was examined. In this ongoing modeling work, MIT estimates that using 2.7% and 3.5% sulfur content in fuel would cause a global average cooling of 0.2°C or more." "35559514100;36545079300;55755291300;57201083597;57201084076;","Simulation of FY-2D infrared brightness temperature and sensitivity analysis to the errors of WRF simulated cloud variables",2018,"10.1007/s11430-017-9150-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043395856&doi=10.1007%2fs11430-017-9150-0&partnerID=40&md5=0846cae4ec2a1f58926562dc8c62c8ed","This study simulated FY-2D satellite infrared brightness images based on the WRF and RTTOV models. The effects of prediction errors in WRF micro- and macroscale cloud variables on FY-2D infrared brightness temperature accuracy were analyzed. The principle findings were as follows. In the T+0–48 h simulation time, the root mean square errors of the simulated brightness temperatures were within the range 10–27 K, i.e., better than the range of 20–40 K achieved previously. In the T +0–24 h simulation time, the correlation coefficients between the simulated and measured brightness temperatures for all four channels were >0.5. The simulation performance of water channel IR3 was stable and the best. The four types of cloud microphysical scheme considered all showed that the simulated values of brightness temperature in clouds were too high and that the distributions of cloud systems were incomplete, especially in typhoon areas. The performance of the THOM scheme was considered best, followed in descending order by the WSM6, WDM6, and LIN schemes. Compared with observed values, the maximum deviation appeared in the range 253–273 K for all schemes. On the microscale, the snow water mixing ratio of the THOM scheme was much bigger than that of the other schemes. Improving the production efficiency or increasing the availability of solid water in the cloud microphysical scheme would provide slight benefit for brightness temperature simulations. On the macroscale, the cloud amount obtained by the scheme used in this study was small. Improving the diagnostic scheme for cloud amount, especially high-level cloud, could improve the accuracy of brightness temperature simulations. These results could provide an intuitive reference for forecasters and constitute technical support for the creation of simulated brightness temperature images for the FY-4 satellite. © 2018, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature." "57200859113;56100874900;57214661259;57202423709;57200855471;57200854611;","Retrieval Algorithm for Broadband Albedo at the Top of the Atmosphere",2018,"10.1007/s13143-018-0001-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048292977&doi=10.1007%2fs13143-018-0001-7&partnerID=40&md5=840202a2e315cb7b1e797817d5b6418b","The objective of this study is to develop an algorithm that retrieves the broadband albedo at the top of the atmosphere (TOA albedo) for radiation budget and climate analysis of Earth’s atmosphere using Geostationary Korea Multi-Purse Satellite/Advanced Meteorological Imager (GK-2A/AMI) data. Because the GK-2A satellite will launch in 2018, we used data from the Japanese weather satellite Himawari-8 and onboard sensor Advanced Himawari Imager (AHI), which has similar sensor properties and observation area to those of GK-2A. TOA albedo was retrieved based on reflectance and regression coefficients of shortwave channels 1 to 6 of AHI. The regression coefficient was calculated using the results of the radiative transfer model (SBDART) and ridge regression. The SBDART used simulations of the correlation between TOA albedo and reflectance of each channel according to each atmospheric conditions (solar zenith angle, viewing zenith angle, relative azimuth angle, surface type, and absence/presence of clouds). The TOA albedo from Himawari-8/AHI were compared to that from the National Aeronautics and Space Administration (NASA) satellite Terra with onboard sensor Clouds and the Earth’s Radiant Energy System (CERES). The correlation coefficients between the two datasets from the week containing the first day of every month between 1st August 2015 and 1st July 2016 were high, ranging between 0.934 and 0.955, with the root mean square error in the 0.053-0.068 range. © 2018, Korean Meteorological Society and Springer Nature B.V." "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." "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)." "35779178900;11240723300;35306297300;7407116104;","Polarimetric Technique for Satellite Remote Sensing of Superthin Clouds",2018,"10.1016/B978-0-12-810437-8.00007-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85041126730&doi=10.1016%2fB978-0-12-810437-8.00007-4&partnerID=40&md5=005dd054a4902686e1a05d01e6fea0ac","Superthin clouds with optical depths smaller than ~. 0.3 exist globally and can seriously affect the remote sensing of aerosols, surface temperature, and atmospheric composition. Failing to detect these clouds, the sea-surface temperature retrieved from NASA's Atmospheric Infrared Sounder (AIRS) satellite data is ~. 5-10. K lower than true values at tropical and midlatitude regions, where these clouds frequently exist. Unfortunately, superthin clouds generally cannot be detected by passive satellite instruments that use only total intensity for measurements. Long-term global surveys of superthin clouds using space-borne lidars are limited by the large operational cost and narrow field of view of these active instruments. This chapter reviews the algorithm for remote sensing of superthin clouds based on our previous study results (Sun et al., 2014, 2015), which show that superthin clouds can be well detected by a polarimetric imager facing toward the backscattering direction of sunlight, exploiting a distinct, characterizing feature of the angle of linear polarization of the backscattered solar radiation (NASA Technology GSC-17392-1). If implemented for satellite remote sensing of the Earth-atmosphere system, this technology will greatly improve the detection of superthin clouds and tremendously impact the remote sensing of clouds, aerosols, surface temperature, atmospheric composition gases, and thus significantly improving data for climate modeling. © 2018 Elsevier Inc. All rights reserved." "22939192200;36118090300;57203012560;56224155200;","Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models",2017,"10.1007/s00376-017-6089-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020420925&doi=10.1007%2fs00376-017-6089-3&partnerID=40&md5=59d5b31d0171e62e17d5381c8183833b","Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850–2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006–2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about −0.99% K−1 and net radiative warming of 0.46 W m−2 K−1, suggesting a role of positive feedback to global warming. © 2017, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag GmbH Germany." "57194504025;7202970886;","A MODIS-derived value-added climatology of maritime cloud liquid water path that conserves solar reflectance",2017,"10.1175/JAMC-D-16-0241.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020379359&doi=10.1175%2fJAMC-D-16-0241.1&partnerID=40&md5=158c9b762cca52d6345bae5893d60d81","A dataset is generated from a method to retrieve distributions of cloud liquid water path over partially cloudy scenes. The method was introduced in a 2011 paper by Foster and coauthors that described the theory and provided test cases. Here it has been applied to Moderate Resolution Imaging Spectroradiometer (MODIS) collection-5 and collection-6 cloud products, resulting in a value-added dataset that contains adjusted distributions of cloud liquid water path for more than 10 years for marine liquid cloud for both Aqua and Terra. This method adjusts horizontal distributions of cloud optical properties to be more consistent with observed visible reflectance and is especially useful in areas where cloud optical retrievals fail or are considered to be of low quality. Potential uses of this dataset include validation of climate and radiative transfer models and facilitation of studies that intercompare satellite records. Results show that the fit method is able to reduce bias between observed visible reflectance and that derived from optical retrievals by up to an average improvement of 3%. The level of improvement is dependent on several factors, including seasonality, viewing geometry, cloud fraction, and cloud heterogeneity. Applications of this dataset are explored through a satellite intercomparison with PATMOS-x and Global Change Observation Mission-First Water (GCOM-W1; ""SHIZUKU"") AMSR-2 and use of a Monte Carlo radiative transfer model. From the 3D Monte Carlo model simulations, albedo biases are found when the method is applied, with seasonal averages that range over 0.02-0.06. © 2017 American Meteorological Society." "55445126300;8886508600;","Spatiotemporal global climate model tracking",2017,"10.4324/9781315371740","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051808132&doi=10.4324%2f9781315371740&partnerID=40&md5=7865b472a8d5ffffd1958159cfa3d78d","We seek to combine the predictions of global climate models in the spatiotemporal setting by incorporating spatial influence into the problem of learning with expert advice. Climate models, in particular general circulation models (GCMs), are mathematical models that simulate processes in the atmosphere and ocean such as cloud formation, rainfall, wind, ocean currents, radiative transfer through the atmosphere and so on and are used to make climate forecasts. GCMs designed by different laboratories will often produce significantly different predictions as a result of the varying assumptions and principles that are used to derive the models. The Intergovernmental Panel on Climate Change (IPCC) is informed by different GCMs from a number of different laboratories and groups. Due to the high variance between the different models, climate scientists are currently interested in methods to combine the predictions of this “multimodel ensemble,” as indicated at the IPCC Expert Meeting on Assessing and Combining Multi-Model Climate Projections in 2010 © 2017 by Taylor & Francis Group, LLC." "56182620500;7401796996;8629713500;7404829395;7004364155;","A clear-sky radiation closure study using a one-dimensional radiative transfer model and collocated satellite-surface-reanalysis data sets",2016,"10.1002/2016JD025823","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029217409&doi=10.1002%2f2016JD025823&partnerID=40&md5=0507c0d7481c7fe8ba9091ad7efb738b","Earth’s climate is largely determined by the planet’s energy budget, i.e., the balance of incoming and outgoing radiation at the surface and top of atmosphere (TOA). Studies have shown that computing clear-sky radiative fluxes are strongly dependent on atmospheric state variables, such as temperature and water vapor profiles, while the all-sky fluxes are greatly influenced by the presence of clouds. NASA-modeled vertical profiles of temperature and water vapor are used to derive the surface radiation budget from Clouds and Earth Radiant Energy System (CERES), which is regarded as one of the primary sources for evaluating climate change in climate models. In this study, we evaluate the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalyzed clear-sky temperature and water vapor profiles with newly generated atmospheric profiles from Department of Energy Atmospheric Radiation Measurement (ARM)-merged soundings and Aura Microwave Limb Sounder retrievals at three ARM sites. The temperature profiles are well replicated in MERRA-2 at all three sites, whereas tropospheric water vapor is slightly dry below ~700 hPa. These profiles are then used to calculate clear-sky surface and TOA radiative fluxes from the Langley-modified Fu-Liou radiative transfer model (RTM). In order to achieve radiative closure at both the surface and TOA, the ARM-measured surface albedos and aerosol optical depths are adjusted to account for surface inhomogeneity. In general, most of the averaged RTM-calculated surface downward and TOA upward shortwave and longwave fluxes agree within ~5 W/m2 of the observations, which is within the uncertainties of the ARM and CERES measurements. Yet still, further efforts are required to reduce the bias in calculated fluxes in coastal regions. © 2016. American Geophysical Union. All Rights Reserved." "55656926800;7404090918;7404240633;55656250400;","Trends of MSU brightness temperature in the middle troposphere simulated by CMIP5 models and their sensitivity to cloud liquid water",2015,"10.1175/JTECH-D-13-00250.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980315249&doi=10.1175%2fJTECH-D-13-00250.1&partnerID=40&md5=3982b6ba5c3aa1defcdde8e4310307fa","Only a climate model that is able to simulate well the historical atmospheric temperature trend can be used for estimating the future atmospheric temperature trends on different emission scenarios. Satellite-based Microwave Sounding Unit (MSU) brightness temperature in the middle troposphere (T2) is an important analog of midtropospheric atmospheric temperature. So, there is the need to compare the atmospheric temperature trend simulated by the fifth phase of the Coupled Model Intercomparison Project (CMIP5) historical realizations and the observed MSU T2. There are two approaches for estimating modeled MSU T2: apply a global-mean static weighting function to generate the weighted average of the modeled temperature at all atmospheric layers and simulate satellite-view MSU T2 using the model's output as input into a radiative transfer model (RTM). In this paper, the two approaches for estimating modeled MSU T2 are evaluated. For each CMIP5, it is shown that there exists a model-simulated static weighting function, such that the MSU T2 trend using the weighting function is equivalent to that calculated by RTM. The effect of modeled cloud liquid water on MSU T2 trends in CMIP5 simulations is investigated by comparing the modeled cloud liquid water vertical profile and the weighting function. Moreover, it is found that warming trends of MSU T2 for CMIP5 simulations calculated by the RTM are about 15% less than those using the two traditional static weighting functions. By comparing the model-derived weighting function with the two traditional weighting functions, the reason for the systematical biases is revealed. © 2015 American Meteorological Society." "56575686800;7201485519;55537426400;10241462700;","Erratum to: The cloud radiative effect on the atmospheric energy budget and global mean precipitation [Clim Dyn, DOI 10.1007/s00382-014-2174-9]",2015,"10.1007/s00382-014-2311-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028152010&doi=10.1007%2fs00382-014-2311-5&partnerID=40&md5=46b071980f5768d1dc64660aa7708c92",[No abstract available] "24757696000;7004154626;24329545900;7102797196;55510783800;55742914900;","Assessment and validation of i-skyradiometer retrievals using broadband flux and MODIS data",2014,"10.1155/2014/849279","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896380105&doi=10.1155%2f2014%2f849279&partnerID=40&md5=40f911605ce3bcdf0533746fad873900","Ground-based network of cloud measurements is presently limited and there exists uncertainty in the cloud microphysical parameters derived from ground-based measurements. Bias in the i-skyradiometer derived cloud optical depth (τ c) and droplet effective radius (R eff) and the importance of these parameters in the parameterization of clouds in climate models have made us intend to develop a possible method for improving these parameters. A new combination method, which uses zenith sky transmittance and surface radiation measurements, has been proposed in the present study to improve the retrievals. The i-skyradiometer derived parameters τ c and R eff have been provided as a first guess to a radiative transfer model (SBDART) and a new retrieval algorithm has been implemented to obtain the best combination of τ c and R eff having minimum bias (-0.09 and -2.5) between the simulated global and diffuse fluxes at the surface with the collocated surface radiation measurements. The new retrieval method has improved τ c and R eff values compared to those derived using the transmittance only method and are in good agreement with the MODIS satellite retrievals. The study therefore suggests a possible improvement of the i-skyradiometer derived cloud parameters using observed radiation fluxes and a radiative transfer model. © 2014 S. Dipu et al." "7405361965;","Effects of vertical wind shear, radiation and ice microphysics on precipitation efficiency during a torrential rainfall event in China",2013,"10.1007/s00376-013-3007-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84886879568&doi=10.1007%2fs00376-013-3007-1&partnerID=40&md5=2e66800868ae5783f1fb840d57158049","The effects of vertical wind shear, radiation and ice microphysics on precipitation efficiency (PE) were investigated through analysis of modeling data of a torrential rainfall event over Jinan, China during July 2007. Vertical wind shear affected PE by changing the kinetic energy conversion between the mean and perturbation circulations. Cloud-radiation interaction impacted upon PE, but the relationship related to cloud radiative effects on PE was not statistically significant. The reduction in deposition processes associated with the removal of ice microphysics suppressed efficiency. The relationships related to effects of vertical wind shear, radiation and ice clouds on PEs defined in cloud and surface rainfall budgets were more statistically significant than that defined in the rain microphysical budget. © 2013 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg." "55576500100;35917252100;52264873100;57201725986;7202772927;","Effects of vertical wind shear, radiation, and ice clouds on precipitation distributions during a landfall of severe Tropical Storm, Bilis (2006)",2013,"10.3319/TAO.2013.01.11.02(A)","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84878861418&doi=10.3319%2fTAO.2013.01.11.02%28A%29&partnerID=40&md5=fc377aa9217c87b4ee4c432360fb71a4","Torrential rainfall responses to vertical wind shear, radiation, and ice clouds during the landfall of severe Tropical Storm, Bilis (2006) are investigated via a rainfall partitioning analysis of grid-scale sensitivity experiment data. The rainfall data are partitioned into eight types based on surface rainfall budget. The largest contributions to total rainfall come from local atmospheric moistening, water vapor convergence, and hydrometeor loss/convergence (Type 3; 29%) when the large-scale upward motions occurred only in the upper troposphere on 15 July 2006. When the large-scale upward motion center moved to the mid troposphere on 16 July, Type 3 hydrometeor loss/convergence (26%) plus local atmospheric drying, water vapor divergence, and hydrometeor loss/convergence (Type 5; 25%) show equally important contributions to total rainfall. The exclusion of vertical wind shear primarily reduced Type 5 rainfall because of the weakened hydrometeor loss/convergence on 16 July. The removal of cloud radiative effects enhances Type 5 rainfall due to increased local atmospheric drying and hydrometeor loss/convergence on 15 July. The elimination of ice clouds generally reduced Type 2 rainfall through the decreases in local atmospheric drying, water vapor convergence, and hydrometeor gain/divergence and Type 3 rainfall over two days." "55705228300;7003922583;7005174340;36620394700;23006117300;","Cloud retrieval using ship-based spectral transmissivity measurements",2013,"10.1063/1.4804757","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877872321&doi=10.1063%2f1.4804757&partnerID=40&md5=e9011e2304ab823c87543ce71d31e8c4","Within the scope of the OCEANET-Project (autonomous measurement platforms for energy and material exchange between ocean and atmosphere) on board of the research vessel Polarstern clouds have been investigated over the Atlantic Ocean under different atmospheric conditions and climate zones by active and passive remote sensing. An existing measurement platform, including lidar, microwave radiometer, all sky camera and broadband radiation sensors, has been extended by spectral radiation measurements with the COmpact RAdiation measurements System (CORAS). CORAS measures spectral downward radiances and irradiances in the visible to near-infrared wavelength region. The data were corrected to consider the movements of the ship and with it the misalignment of the sensor plane from earth's horizon. Using observed and modeled spectral transmitted radiances cloud properties such as cloud optical thickness (τ) and effective radius (r eff) were retrieved. The vertical cloud structure with limitations for thick clouds is obtained from lidar and microwave radiometer measurements. The all sky camera provides information on the horizontal cloud variability. Cloud optical thickness and effective radius, will be retrieved by using a plane parallel radiative transfer model. © 2013 AIP Publishing LLC." "55706651200;8385562400;55489090900;14042894900;8948450600;","Retrieval of volcanic ash and ice cloud physical properties together with gas concentration from IASI measurements using the AVL model",2013,"10.1063/1.4804718","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877864146&doi=10.1063%2f1.4804718&partnerID=40&md5=e16b3742fbaf486e7b8569c5b8814c61","Observation and tracking of volcanic aerosols are important for preventing possible aviation hazards and determining the influence of aerosols on climate. The useful information primary includes the concentration, particle size and altitude of aerosol load. Moreover, volcanic eruptions are usually accompanied by strong emissions of SO2 and enhanced concentrations of H 2O in the atmosphere. Volcanic ash particles can also catalyze the formation of ice clouds by serving as cloud nuclei. Hyperspectral infrared sounders, such as IASI (Infrared Atmospheric Sounding Interferometer), have proven to be powerful tools for capturing volcanic aerosol and ice cloud signatures and enhanced volcanic gas concentrations. Information on atmospheric constituents is extracted from such hyperspectral measurements with the help of radiative transfer (RT) codes capable of solving both direct and inverse RT problems. We will demonstrate the retrieval of aerosol and ice cloud physical properties together with gas concentration from IASI measurements with the help of the AVL RT model. AVL is one of the 'code combination packages' which are becoming more and more popular in the scientific domain. It consists of several codes, each of which handles a specific set of physics-related tasks. The codes function smoothly as a whole due to the use of a special interface. AVL is perfectly suitable (i) to model the propagation of UV-visible-IR radiation through a coupled atmosphere-surface system for a wide range of atmospheric, spectral and geometrical conditions; and (ii) to retrieve vertical gas profiles and aerosol concentration through the use of its embedded retrieval algorithm on the basis of an optimal estimation method (OEM). The retrievals are performed for IASI measurements (radiance, Level 1C product) carried out over Eyjafjallajökull volcano, Iceland, in April 2010. © 2013 AIP Publishing LLC." "55576500100;55865532800;35917252100;52264873100;57201725986;7202772927;","Cloud microphysical budget associated with torrential rainfall during the landfall of severe tropical storm Bilis (2006)",2013,"10.1007/s13351-013-0210-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882805437&doi=10.1007%2fs13351-013-0210-z&partnerID=40&md5=cc7bb42ab4983dede9d28f4afd053da6","Effects of vertical wind shear, radiation, and ice clouds on cloud microphysical budget associated with torrential rainfall during landfall of severe tropical storm Bilis (2006) are investigated by using a series of analysis of two-day grid-scale sensitivity experiment data. When upper-tropospheric upward motions and lower-tropospheric downward motions occur on 15 July 2006, the removal of vertical wind shear and ice clouds increases rainfall contributions from the rainfall type (CM) associated with positive net condensation and hydrometeor loss/convergence, whereas the exclusion of cloud radiative effects and cloud-radiation interaction reduces rainfall contribution from CM. The elimination of vertical wind shear and cloud-radiation interaction increases rainfall contribution from the rainfall type (Cm) associated with positive net condensation and hydrometeor gain/divergence, but the removal of cloud radiative effects and ice clouds decreases rainfall contribution from Cm. The enhancements in rainfall contribution from the rainfall type (cM) associated with negative net condensation and hydrometeor loss/convergence are caused by the exclusion of cloud radiative effects, cloud-radiation interaction and ice clouds, whereas the reduction in rainfall contribution from cM results from the removal of vertical wind shear. When upward motions appear throughout the troposphere on 16 July, the exclusion of all these effects increases rainfall contribution from CM, but generally decreases rainfall contributions from Cm and cM. © 2013 The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg." "55556288600;7403079681;","A new method for retrieving equivalent cloud base height and equivalent emissivity by using the ground-based Atmospheric Emitted Radiance Interferometer (AERI)",2013,"10.1007/s11430-012-4398-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84872283026&doi=10.1007%2fs11430-012-4398-z&partnerID=40&md5=41d58138641010c19b2452117f9e0ef8","In the paper, we propose a new method of identifying the clear sky based on the Atmospheric Emitted Radiance Interferometer (AERI). Using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AFM) dataset in Shouxian in 2008, we simulate the downwelling radiances on the surface in the 8-12 μm window region using Line-By-Line Radiative Transfer Model (LBLRTM), and compare the results with the AERI radiances. The differences larger (smaller) than 3 mW (cm2 sr cm-1)-1 suggest a cloudy (clear) sky. Meanwhile, we develop the new algorithms for retrieving the zenith equivalent cloud base height (CBHe) and the equivalent emissivity (e{open}e), respectively. The retrieval methods are described as follows. (1) An infinitely thin and isothermal blackbody cloud is simulated by the LBLRTM. The cloud base height (H) is adjusted iteratively to satisfy the situation that the contribution of the blackbody to the downwelling radiance is equal to that of realistic cloud. The final H is considered as CBHe. The retrieval results indicate that the differences between the CBHe and observational cloud base height (CBH) are much smaller for thick low cloud, and increase with the increasing CBH. (2) An infinitely thin and isothermal gray body cloud is simulated by the LBLRTM, with the CBH specified as the observed value. The cloud base emissivity (e{open}c) is adjusted iteratively until the contribution of the gray body to the downwelling radiance is the same as that of realistic cloud. The corresponding e{open}c is e{open}e. The average e{open}e for the low, middle, and high cloud is 0. 967, 0. 781, and 0. 616 for the 50 cases, respectively. It decreases with the increasing CBH. The retrieval results will be useful for studying the role of cloud in the radiation budget in the window region and cloud parameterizations in the climate model. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg." "56033330500;57196170962;7402764213;","Numerical experiments of an advanced radiative transfer model in the U.S. Navy operational global atmospheric prediction system",2012,"10.1175/JAMC-D-11-018.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861692961&doi=10.1175%2fJAMC-D-11-018.1&partnerID=40&md5=494d37144f99a1c18c51b1379f272989","Ahigh-order accurate radiative transfer (RT) model developed by Fu and Liou has been implemented into the Navy Operational Global Atmospheric Prediction System (NOGAPS) to improve the energy budget and forecast skill. The Fu-LiouRT model is a four-stream algorithm (with a two-stream option) integrating over 6 shortwave bands and 12 longwave bands. The experimental 10-day forecasts and analyses from data assimilation cycles are compared with the operational output, which uses a two-stream RT model of three shortwave and five longwave bands, for both winter and summer periods. The verifications against observations of radiosonde and surface data show that the new RT model increases temperature accuracy in both forecasts and analyses by reducing mean bias and root-mean-square errors globally. In addition, the forecast errors also grow more slowly in time than those of the operational NOGAPS because of accumulated effects of more accurate cloud-radiation interactions. The impact of parameterized cloud effective radius in estimating liquid and ice water optical properties is also investigated through a sensitivity test by comparing with the cases using constant cloud effective radius to examine the temperature changes in response to cloud scattering and absorption. The parameterization approach is demonstrated to outperform that of constant radius by showing smaller errors and better matches to observations. This suggests the superiority of the new RT model relative to its operational counterpart, which does not use cloud effective radius. An effort has also been made to improve the computational efficiency of the new RT model for operational applications. © 2012 American Meteorological Society." "16029830700;","Investigation of the oceanic cloudiness according to the data of satellite observations in the spectral range 10.3-11.3 μm",2011,"10.1007/s11110-011-9098-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-79958839929&doi=10.1007%2fs11110-011-9098-2&partnerID=40&md5=0f5138bd473ae6cd05d692d380b41576","The temperature of waters in the upper layer of the ocean and effective cloudiness (cloudiness with simultaneous indication of its amount and optical density) are important characteristics of the natural environments. They determine the greenhouse effects and the energy of the ocean and atmosphere, and regulate climate. The satellite data on these characteristics enable one to reconstruct all components of the radiation, heat, and water budgets in the ocean-atmosphere system and study their intra- and interannual variations. We describe the procedures of evaluation of the effective cloudiness according to the sea-surface temperature and the radiation temperature in the spectral range 10.3-11.3 μm. The development of these investigations is connected with the advances in satellite hydrophysics: the satellite data become more and more accurate, regular, and global. © 2011 Springer Science+Business Media, Inc." "7403282069;8891521600;7801693068;","Use of CERES cloud and radiation data for model evaluation and cloud feedback studies",2009,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-78149342130&partnerID=40&md5=a16300f5a92e46dd2d82048261f7578a","The availability of enormous amounts of satellite remote sensing data provides a golden opportunity to improve the capability of climate models for projecting future climate change. In this study, we will present recent progress in using CERES (Clouds and the Earth's Radiant Energy System) satellite data to evaluate model performance with regards to the vertical structures of radiative fluxes and cloud radiative effects and to provide an unambiguous estimate of the magnitude of low cloud feedbacks." "7401928630;6505905181;","Aerosol black carbon - Globally the #2 greenhouse 'gas'",2009,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-73349139865&partnerID=40&md5=ca2e8a2f5434311d2c38526eba3b0fc2","'Black Carbon' aerosol particles are produced in all combustion of carbonaceous fuels. Increasing the efficiencies of combustion and filtration can reduce, but not completely eliminate, their discharge. Once released to the atmosphere, they interact with radiative transfer both directly (through absorption of light) and indirectly (through modification of clouds). When deposited on snow or ice, they reduce the surface albedo leading to increased absorption of sunlight and accelerated thawing. On a global scale, Black Carbon aerosols are the second most important anthropogenic contributor to climate forcing, second only to CO2. For example, extreme carbonaceous aerosol concentrations in Asia form 'atmospheric brown clouds' which lead to observed shifts in patterns of precipitation; reduction in agricultural output; and predicted possible failure of the monsoon. Control of particulate emissions is economically and politically far more feasible than curtailment of primary energy production from fossil fuels. The relatively short lifetime of aerosols in the atmosphere means that reductions in emissions will result in immediate benefits. In addition to their climate-forcing consequences, Black Carbon aerosols (with their associated adsorbed toxics) are the leading indicator of adverse public health impacts. This presentation will review the production and properties of Black Carbon aerosols, and the technologies most commonly used for their measurement in both source and ambient atmospheres. We shall focus on optical methods of detection which offer rapid real-time analysis, lightweight portability, and analysis at multiple wavelengths to permit the discrimination of aerosols from different sources such as diesel and biomass or coal combustion." "24780687700;7403203783;8437626600;56412340900;","Multiangular polarized characteristics of cirrus clouds at 1380 NM",2008,"10.1109/IGARSS.2008.4779887","https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649806812&doi=10.1109%2fIGARSS.2008.4779887&partnerID=40&md5=aee7b80a9f194aa6553925acf7871c3a","Cirrus clouds are known to play a key role in the Earth's radiation budget and global climate change, the radiative effects of cirrus clouds depend critically on cloud properties such as optical thickness and particle shape and size. The studies of the optical, microphysical, and physical properties of cirrus have become the popular issue. This paper simulated the bidirectional reflectance distribution function (BRDF) and bidirectional polarization reflectance distribution function (BPDF) at 1380nm in cirrus cloudy conditions on the basis of an adding-doubling radiative transfer program. Based on the sensitivity of 1380nm spectral reflectance and polarization reflectance on cirrus optical thickness and aspect ratio, a conceptual approach has been developed to simultaneous retrieve the particle shape and optical thickness of cirrus clouds using the remote sensing data of multi-angular total and polarized at 1380nm. © 2008 IEEE." "7404078977;15751136900;6602844274;53869267200;53868700700;55495155800;","Inter-comparison of solar resource data sets: NASA-SRB/SSE versus DLR-ISIS global and beam irradiance",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845798488&partnerID=40&md5=ffce963e1fd06e431483196d847d416e","Two satellite-derived solar irradiance data sets covering the full globe are compared against each other. One is NASA's SSE (Surface meteorology and Solar Energy) data set, the other DLR's ISIS (Irradiance at the Surface derived from ISCCP cloud data). Both consist of boxes with coarse spatial resolution: SSE has approximately 100 km wide boxes, ISIS 280 km. Both data sets are based on long-term archives: SSE so far covers 10 years, ISIS 21 years. Also both data sets offer information on global hemispherical irradiance and direct normal irradiance, required for planning of concentrating or tracking solar energy devices. The two satellite schemes use differing cloud detection, aerosols and water vapor, and separate radiative transfer calculations. Comparing both data sets in 12 different regions worldwide allows analyzing effects of different climates and satellite viewing geometries on quality. It is found that both data sets agree reasonably well for global irradiance indicated by an RMS deviation below 9%. On average over all regions SSE reports approximately 6% less irradiance than ISIS. This bias is similar for direct normal irradiance, but RMS is much higher exceeding 20%." "6701797047;55675224272;56709439000;15059116900;6602724321;","Signatures of atmospheric and surface climate variables through analyses of infra-red spectra (SATSCAN-IR)",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845764252&partnerID=40&md5=0111a181d3f0af0834d50be7c5ae4fdb","The objective of the SATSCAN-IR project is to apply focussed and ""whole spectrum"" modelling to global level 1 spectra determined by the Infrared Atmospheric Sounding Interferometer (IASI) instrument in order (1) to provide internal calibration/validation information on the quality of the level 1 spectra, (2) to verify radiative transfer modelling of entire nadir infra-red spectra; (3) to identify interesting spectral features in the data and investigate both their implications for IASI data quality and for scientific exploitation. The approach builds on work developed for the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT where application of our techniques resulted in characterisation of instrument offsets, cloud effects, verification of known spectral features such as HCFC22, and detection of new spectral features for organic compounds. Deliverables of the IASI investigations will be a characterisation of radiative transfer accuracy and IASI level 1 spectral accuracy, a) at frequencies employed by IASI level 2 retrievals; 2) across the entire IASI spectrum. Outputs are likely to include assessment of absolute calibration and, as important, variability of calibration from orbit to orbit and day to day. Representative geophysical locations for monitoring will be identified. Spectral effects that might need to be considered include a) signatures of weakly absorbing tropospheric trace gases; b) Saharan dust; c) variations of surface emissivity. The work will make use of MIPAS reference atmospheres, an important element in simulations of infra-red spectra, which will be updated for IASI applications." "57202531041;6506606807;55893487700;14020751800;57191680975;8722460900;","Remote sensing ofwater and ice clouds from MSG/SEVIRI",2006,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-33750553128&partnerID=40&md5=caf75e853a1d9a9f36d0a4b2fdd24e43","Clouds and their interaction with radiation are still one of the main uncertainties in our understanding of present and the prediction of future climate. Within the framework of the MSG RAO-project we have developed a new water and ice cloud detection and microphysical properties remote sensing algorithm, APICS (Algorithm for the Physical Interpretation of Clouds with SEVIRI). An MSG cirrus detection algorithm (MeCiDA) was developed with special emphasis on optically thin ice clouds. Finally, a fast method to derive top-of-atmosphere radiation fluxes from MSG was developed. With these tools we studied the impact of air traffic on cirrus cloud cover and on the Earth's radiation budget. Our current work concentrates on the generation of artificial satellite images, combining our experience with remote sensing of inhomogeneous clouds and radiative transfer. This manuscript is an update of the paper produced for the 2nd RAO workshop and summarizes the final results." "57197885680;7401795483;6602185328;35121795500;55946567900;","Estimation of snowfall over the sea of Japan using AMSR-E passive microwave remote sensing observation",2004,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-15944373954&partnerID=40&md5=1cf5af88cde073096f32d7b2533ad206","Snowfall is an important geophysical parameter and the observation of the spatial and temporal distribution of snowfall can provide valuable information for a wide range of applications including climate change studies and atmospheric modelling. This paper investigates the feasibility to estimates the amount of solid precipitation and the cloud liquid water content over the ocean using AMSR-E passive microwave brightness temperature observations. The parameters are retrieved by minimizing the difference between the observed and modeled brightness temperature. The radiative transfer in the atmosphere is solved using the discrete ordinate method (4 streams) and the Henyey-Greenstein phase function. The scattering effect of the snow particles is calculated using Mie theory and the liquid-equivalent size of the ice particle. Except for the snowfall and the cloud liquid water content, most parameters, which influence the observation are derived from other data sources. The Newton-Raphson method is used to solve the iteration process using observed brightness temperatures at 89 GHz vertical polarization and 36.5 GHz horizontal polarization. The algorithm was applied using data from the Wakasa Bay Experiment 2003 in Japan and the results are compared to snowfall observation derived using a Z-R relationship and data from the Mikuni Doppler radar. Good agreement was achieved for different atmospheric conditions." "12242288500;7003652577;","The effect of differential cloud cover on the propagation of a surface cold front",2004,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442581034&partnerID=40&md5=cf6e38308db0b3a5b466e364a46d4bb2","The impact of differential cloud cover on the propagation of a surface cold front and a sensitivity simulation was performed to gain insight into cloud radiative effects on the front. A control (CTL) simulation and a no cloud radiation interaction (RAD) simulation were performed using the Betts-Miller convective parameterization, the Eta planetary boundary layer scheme and the mixed phase microphysics package. A comparison of the two simulations for the distribution of cloud cover associated with the movement of the primary frontal zone revealed that the cloud cover was identical in shape and relative position for the two simulations. The results by the CTL simulation show more frontal propagation from 00 to 06 UTC than corresponding RAD simulation." "7004242319;56170404000;","Use of in-situ observations of arctic clouds to understand impacts of mixed-phase clouds on single-scattering: Properties: Applications to climate models",2004,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442560209&partnerID=40&md5=a0552049173bfddaa6cf0910538b4a78","The in-situ measurements to examine nature of phase mixing and contributions of water and ice to mixed-phase single-scattering in the Arctic are discussed. To characterize the nature of in-situ observations in context of physical processes which lead to production and dissipation of clouds, lidar, radar and radiometer data are used. The mean scattering properties of observed clouds are derived by weighting single-scattering properties of ice crystals and water droplets. Plane-parallel radiative transfer model is used to show differences in cloud radiative forcing." "55262499900;35413553600;7004801727;7405614202;55702592400;7003840159;57214125725;7004316179;","GIFTS - Hyperspectral imaging and sounding from geostationary orbit",2004,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442432408&partnerID=40&md5=769ef8cedf719fbbce96de734a73cb73","The application of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) to observe surface thermal properties and atmospheric weather, is discussed. GIFTS measurement concept for altitude-resolved 'water vapor winds' and the revolutionary technologies for research and operational system are also discussed. It is observed that the application of GIFTS technologies into operational instrumentation is critical for optimizing geostationary weather and climate observing system. The GIFTS sounding concept and algorithms are validated using AQUA satellite AIRS date and airborne NAST-I high spectral resolution radiance measurement." "57202531041;6506606807;55893487700;57191680975;6601974795;6603416853;8722460900;","Remote sensing of waterand ice clouds from MSG/SEVIRI",2004,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-23844488866&partnerID=40&md5=be7efc1a06cb7df3343319242008f59f","Clouds and their interaction with radiation are still one of the main uncertainties in our understanding of present and the prediction of future climate. MSG/SEVIRI - with its unique combination of time and spatial resolution and spectral information - has the potential of contributing significantly to the reduction of this gap. We have developed a new water and ice cloud detection and microphysical properties remote sensing algorithm. Cloud detection and classification is based on a prototype version of the EUMETSAT Scenes Analysis scheme, with a particular emphasis on the detection of thin ice clouds. Cloud microphysical properties are retrieved using tabulated forward calculations by a detailed radiative transfer code, libRadtran, which takes into account cloud phase, microphysical properties as well as a complete description of the background atmosphere and surface. Particular attention is given to the treatment of inhomogeneous clouds where we aim at combining the spectral information of the low-resolution channels with the higher spatial resolution of the HRV channel, in order to directly consider sub-pixel cloud inhomogeneity in the retrieval to reduce potential biases." "26643440200;7003899619;","Evaluating the potential for retrieving aerosol optical depth over land from AVHRR pathfinder atmosphere data",2002,"10.1175/1520-0469(2002)059<0279:etpfra>2.0.co;2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085674310&doi=10.1175%2f1520-0469%282002%29059%3c0279%3aetpfra%3e2.0.co%3b2&partnerID=40&md5=9ba6f1a83d968f7a9bf7967a004d387f","In spite of numerous studies on the remote sensing of aerosols from satellites, the magnitude of aerosol climate forcing remains uncertain. However, data from the Advanced Very High Resolution Radiometer (AVHRR) Pathfinder-Atmosphere (PATMOS) dataset-a statistical reduction of more than 19 yr of AVHRR data (1981-2000) could provide nearly 20 yr of aerosol history. PATMOS data have a daily 110 × 110 km2 equal-area grid that contains means and standard deviations of AVHRR observations within each grid cell. This research is a first step toward understanding aerosols over land with PATMOS data. Herein, the aerosol optical depth is retrieved over land at numerous Aerosol Robotic Network (AERONET) sites around the globe using PATMOS cloud-free reflectances. First, the surface bidirectional reflectance distribution function (BRDF) is retrieved using a lookup table created with a radiative transfer model and the Rahman BRDF. Aerosol optical depths are then retrieved using the retrieved BRDF parameters and the PATMOS reflectances assuming a globally constant aerosol model. This method is applied to locations with ground truth measurements, where comparisons show that the best retrievals are made by estimating the surface reflectance using observations grouped by month. Random errors (i.e., correlation coefficients and standard error of estimate) in this case are lower than those where the surface BRDF is allowed year-to-year variations. By grouping the comparison results by land cover type, it was found that less noise is expected over forested regions, with a significant potential for retrieval for 80% of all land surfaces. These results and analyses suggest that the PATMOS data can provide valuable information on aerosols over land." "6603436991;","A monostatic solid state W-band FM-CW doppler profiler",2002,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036401349&partnerID=40&md5=19a0855353a83a5b9dbaf6c15471a185","The Institute for Tropospheric Research (IfT) in Leipzig, Germany, operates a number of airborne in-situ probes for cloud microphysical properties, and ground based and airborne radiation measurement tools. To enhance information about clouds for radiative transfer calculation and research, IfT decided to add a cloud radar to its equipment. In the final state, this radar system shall be applicable for dual purpose operation in ground based and airborne mode." "7404040259;12645090400;","Use of the ATSR series in the construction of a long-term SST record for climate change detection",2000,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0347051426&partnerID=40&md5=9856b0986c1e26ac959031d9da30bdca","The use of along-track scanning radiometer (ATSR) in providing sea surface temperatures (SST) measurements for climate research is discussed. SST is a key diagnostic for climate change detection, and exerts a controlling influence on the exchange of heat between the ocean and the atmosphere. This satellite-based retrieval process is designed to retrieve the skin temperature and is a better parameter to use than the bulk temperature, because it affects the exchange of heat directly. Such measurements are the preserve of specialist oceanographic cruises and are consequently sparsely distributed in both space and time." "56455165800;7003440089;","A sensitivity study of the subtropical ocean surface energy balance to the parameterization of precipitation from stratocumulus clouds",2000,"10.1023/A:1002482230580","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034029273&doi=10.1023%2fA%3a1002482230580&partnerID=40&md5=aa35f4ad70955eb6adafa55852dc3037","In the 'First Lagrangian' of the Atlantic Stratocumulus Experiment (ASTEX), a cloudy air mass was tracked as it was advected by the trade winds toward higher sea surface temperatures. In this study, a full diurnal cycle observed during this experiment is simulated and the impact of the precipitation parameterization is examined. The model we use is the one dimensional version of the hydrostatic primitive equation model MAR (Modele Atmospherique Regional) developed at the Universite catholique de Louvain (UCL). It includes an E-ε turbulence closure, a wide-band formulation of the radiative transfer, and a parameterized microphysical scheme allowing partial condensation. The model realistically reproduces the diurnal clearing of the cloud layer as well as the formation of cumulus clouds under the stratocumulus deck. Nevertheless, as the surface warms and the boundary layer becomes more convective, the simulation progressively differs from the observed evolution. Further experiments are carried out with different precipitation parameterizations commonly used in mesoscale models and general circulation models (GCMs). A strong sensitivity of the simulated liquid water path evolution is found. The impact on the surface energy flux and the solar flux reflected by the cloud is also examined. For both fluxes averaged over 24 hours, differences as large as 20 W m-2 are obtained between the various simulations. Low cloudiness covers large areas over the ocean and such errors on the reflected solar flux may strongly affect the Earth's radiative budget in GCM simulations. We estimate that the impact on the globally averaged outgoing solar flux could be as large as 5 W m-2. Furthermore, when atmospheric models are coupled to ocean models, errors in the surface energy exchanges may induce significant drift in the simulated climate." "7101899854;","Global monitoring and retrievals of atmospheric aerosols and clouds",1997,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030656722&partnerID=40&md5=83350a85a42122e6ef71b49568197d53","A knowledge of aerosol and cloud radiative properties and their variation in space and time is especially crucial to understanding the radiative forcing in all climate related studies. Global monitoring of aerosol and cloud radiative effects relies on advanced Earth Observing Systems. Key advances include simultaneous observation of radiation budget and aerosol/cloud properties, additional information on particle size. phase, and vertical layer structure. Comprehensive radiation models are used to develop retrieval algorithms. An overview of the science and techniques in atmospheric aerosols and clouds remote sensing and retrieval is presented, citing high-quality multispectral imagery and nadir propagating lidar measurements as examples." [No author id available],"Proceedings of the 1994 International Geoscience and Remote Sensing Symposium. Part 2 (of 4)",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028745555&partnerID=40&md5=3249a6ffcd189f1f9ec8cf142326e467","The proceedings contain 180 papers on remote sensing. Topics discussed include remote sensing techniques for various applications such as monitoring clouds, climate change, earth's troposphere, crustal motions, environmental degradation and pollution, ocean winds and sea surface scattering, agriculture and crop monitoring, vegetation fluorescence, lead properties in the Arctic, arid and semi-arid land monitoring, tropical rainforest and wetlands. It also discusses synthetic aperture radar, satellite acquired data, interferometry, data integration and analysis, image classification, sensor calibration and performance verification, polarimetric theory, geographic information systems, mathematical modeling, and algorithms." "6602944180;57198067358;","Early EOS progress report",1994,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028741084&partnerID=40&md5=eb9f146b4e1c99bd75c3e17636c4b1dd","Mission to Planet Earth (MTPE) is an ambitious NASA program with the goal to advance human knowledge of the planet Earth as a system. The Earth Observing System (EOS) program, the principal component of NASA's MTPE, provides the long-term observations and data system infrastructure needed to support interdisciplinary science. Its objective is to develop a comprehensive understanding of the global scale processes that shape and influence the Earth. Some of the scientific advances that have been made since the inception of EOS-IDS program in 1990 are summarized." "7403079681;7403590574;7403309879;","Remote sensing of cloud optical depth with AVHRR and ground-based observation",1994,"10.1016/0273-1177(94)90353-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028333173&doi=10.1016%2f0273-1177%2894%2990353-0&partnerID=40&md5=019427589f95a877ae4aed92d6cd8ce1","The Cloud is one of the most active factors in the physical climate system which may response to global changes of other systems and factors of the global earth system in very complicated manners and rather broad spatial and temporal scales. Therefore, cloud parameters are important targets in satellite and surface-based remote sensing. Presently, quantitative remote sensing of cloud parameters is still at the primary stage because of its complexity in phase, particle size distribution, adsorption and inhomogeneous distribution and rapid variation. In this paper, the comparison of combined observation of cloudy sky (both from NOAA satellite and from ground-based radiation and lidar observation) with radiative transfer model calculations are presented. The differences between observation and model calculation are discussed to illustrate the further steps necessary for reasonable results of cloud parameters. © 1993." "6603746990;7006541319;6701764148;7005729142;","Combining lidar and radar measurements to derive cirrus cloud effective radii: In situ comparison and simplistic model results",1993,"10.1109/COMEAS.1993.700199","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068461852&doi=10.1109%2fCOMEAS.1993.700199&partnerID=40&md5=fdd99a0f29e9bff460ff5d57a785351e","Ice cloud bulk radiative properties derived from cirrus cloud observations were presented. A cirrus cloud was observed by the NOAA Doppler lidar and radar which provided estimates of the ice water path and the effective radius of the size distribution. These measurements were used to parameterize the ice cloud optical properties. The observed cirrus cloud was represented by three distinct periods, characterizing an early tenuous stage by re=30 μm and iwp=5 g m-2, a mid-life convective stage with re = 100 μm and iwp=5 g m-2, and a mature steady phase with re=150 μm and iwp=80 g m-2. The reflectivity, transmissivity, and emissivity calculated for the cirrus cloud, observed over a mid-latitude continental site, were presented and show reasonable results. The thin, tenuous cirrus cloud exhibited the strongest shortwave transmittance and weakest IR emissivity, which indicates that this mid-latitude, shallow cirrus cloud had very little effect on the (upward and downward) IR radiation flux at the surface. This would not be true for other locations. For example, tenuous cirrus are important in the tropics and polar regions where the amount of solar radiation received at the surface has a greater impact on the net flux balance. In the mid-life stages of a cirrus cloud, the possibility of several radiative effects exist. In general, however, a moderately opaque cloud is a less effective reflector and transmitter in the shortwave region due to the increase in particle sizes. As would be expected, the IR emissivity increases substantially thereby changing the net radiative flux and warming the column. This overly simplistic assessment of cloud radiative effects punctuates the need for observations and awareness of all the various factors that must be considered when determining the radiative influence of clouds. A more thorough extension of this study is currently in progress. Using one month of cloud observations obtained in Kansas, combinations of re and iwp can be tabulated to address a more realistic and quantitative cloud analysis. For example, computed fluxes can be compared to the observed short and longwave fluxes in order to assess the accuracy of retrieving iwp and re from remote sensors, and in turn, determine how these quantities perform in the models to predict the cirrus optical properties and their radiative effects. © 1993 IEEE." "24309903400;24310136800;7004944741;7005719900;","Parameterization model of the radiative distribution in an atmospheric column, taking into account the cloud cover: application to Kuwait's fires",1993,"10.1016/0266-9838(93)90021-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-43949173100&doi=10.1016%2f0266-9838%2893%2990021-9&partnerID=40&md5=4f26356a438c4034fbd615e322deb9e2","A 1-D model is presented for calculations of both longwave and shortwave radiant flux distribution along the atmospheric column, in order to study the effect of various energy scenarios on the global climate change. The model evaluates the radiative balance terms relative to the various atmospheric layers, which also take into account the formation and the effects produced by stratified clouds. The computer code consists of two blocks: the first block evaluates the optical properties of the cloud layer, while the latter determines the radiative balance. The paper presents the application of the model to the analysis of the radiative transfer processes which took place in the atmosphere containing the combustion products of the oil well fires above Kuwait. The results fit the observational data of the surface temperature change, giving a first validation of the adequacy of the model in studying well-defined climatic problems. © 1993." "7102113534;7401924358;","A climate index derived from satellite measured spectral infrared radiation.",1982,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020235772&partnerID=40&md5=bf6495863a6420a7fc76fd36be8d594d","The vertical infrared radiative emitting structure (VIRES) climate index, based on radiative transfer theory and derived from the spectral radiances typically used to retrieve temperature profiles, is introduced. It is assumed that clouds and climate are closely related and a change in one will result in a change in the other. The index is a function of the cloud, temperature, and moisture distributions.-from STAR, 20(16), 1982" "7006655968;","Radiative transfer in the cloudy and dusty atmosphere.",1980,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019144374&partnerID=40&md5=957aabdf6dc8f532c74cb783390ee286","Cloudiness is the main factor governing the planetary radiation balance; climate models should allow for cloud-radiation interactions to be properly included. Aerosols have a more subtle influence, as their role is much weaker, but their variations can induce local or global climate variations.- from Author"