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Patrick Minnis - One of the best experts on this subject based on the ideXlab platform.
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a radiation closure study of arctic stratus cloud microphysical properties using the collocated Satellite surface data and fu liou radiative transfer model
2016Co-Authors: Xiquan Dong, Patrick Minnis, Shaoyue Qiu, Sunny Sunmack, Fred G RoseAbstract:Author(s): Dong, X; Xi, B; Qiu, S; Minnis, P; Sun-Mack, S; Rose, F | Abstract: © 2016. American Geophysical Union. Retrievals of cloud microphysical properties based on passive Satellite imagery are especially difficult over snow-covered surfaces because of the bright and cold surface. To help quantify their uncertainties, single-layered overcast liquid-phase Arctic stratus cloud microphysical properties retrieved by using the Clouds and the Earth’s Radiant Energy System Edition 2 and Edition 4 (CERES Ed2 and Ed4) algorithms are compared with ground-based retrievals at the Atmospheric Radiation Measurement North Slope of Alaska (ARM NSA) site at Barrow, AK, during the period from March 2000 to December 2006. A total of 206 and 140 snow-free cases (Rsfc ≤ 0.3), and 108 and 106 snow cases (Rsfcg0.3), respectively, were selected from Terra and Aqua Satellite passes over the ARM NSA site. The CERES Ed4 and Ed2 optical depth (t) and liquid water path (LWP) retrievals from both Terra and Aqua are almost identical and have excellent agreement with ARM retrievals under snow-free and snow conditions. In order to reach a radiation closure study for both the surface and top of atmosphere (TOA) radiation budgets, the ARM precision spectral pyranometer-measured surface albedos were adjusted (63.6% and 80% of the ARM surface albedos for snow-free and snow cases, respectively) to account for the water and land components of the domain of 30 km × 30 km. Most of the radiative transfer model calculated SW↓sfc and SW↑TOA fluxes by using ARM and CERES cloud retrievals and the domain mean albedos as input agree with the ARM and CERES flux observations within 10Wm-2 for both snow-free and snow conditions. Sensitivity studies show that the ARM LWP and re retrievals are less dependent on solar zenith angle (SZA), but all retrieved optical depths increase with SZA.
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estimation of 2006 northern hemisphere contrail coverage using modis data
2013Co-Authors: David P. Duda, Patrick Minnis, Thad Chee, Konstantin V. Khlopenkov, R. BoekeAbstract:[1] A modified automated contrail detection algorithm (CDA) using five infrared channels available from the Moderate Resolution Imaging Spectrometer onboard the Aqua Satellite is used to determine linear contrail coverage over the Northern Hemisphere during 2006. Commercial aircraft flight data are employed to filter false contrail detections by the CDA. The Northern Hemisphere annual mean linear contrail coverage ranges from 0.07% to 0.40% for three different CDA sensitivities. Based on visual analyses, the medium sensitivity CDA provides the best estimate of linear contrail coverage, which averages 0.13%. If scaled to the Southern Hemisphere, the global mean coverage would be 0.07%. Coverage is greatest during winter and least during the summer with maximum coverage over the North Atlantic. Less coverage is observed over heavy European and American traffic areas, likely as a result of difficulties in detecting linear contrails that overlap with each other and with older contrail cirrus. These results are valuable for evaluating the representation of contrails and contrail cirrus within global climate models and for retrieving contrail optical properties and radiative forcing.
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depolarization ratio and attenuated backscatter for nine cloud types analyses based on collocated calipso lidar and modis measurements
2008Co-Authors: Hyounmyoung Cho, Charles R. Trepte, Patrick Minnis, Ping Yang, George W Kattawar, Shaima L Nasiri, David M. WinkerAbstract:This paper reports on the relationship between lidar backscatter and the corresponding depolarization ratio for nine types of cloud systems. The data used in this study are the lidar returns measured by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Satellite and the collocated cloud products derived from the observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua Satellite. Specifically, the operational MODIS cloud optical thickness and cloud-top pressure products are used to classify cloud types on the basis of the International Satellite Cloud Climatology Project (ISCCP) cloud classification scheme. While the CALIPSO observations provide information for up to 10 cloud layers, in the present study only the uppermost clouds are considered. The layer-averaged attenuated backscatter (γ′) and layer-averaged depolarization ratio (δ) from the CALIPSO measurements show both water- and ice-phase features for global cirrus, cirrostratus, and deep convective cloud classes. Furthermore, we screen both the MODIS and CALIPSO data to eliminate cases in which CALIPSO detected two- or multi-layered clouds. It is shown that low γ′ values corresponding to uppermost thin clouds are largely eliminated in the CALIPSO δ–γ′ relationship for single-layered clouds. For mid-latitude and polar regions corresponding, respectively, to latitude belts 30°–60° and 60°–90° in both the hemispheres, a mixture of water and ice is also observed in the case of the altostratus class. MODIS cloud phase flags are also used to screen ice clouds. The resultant water clouds flagged by the MODIS algorithm show only water phase feature in the δ–γ′ relation observed by CALIOP; however, in the case of the ice clouds flagged by the MODIS algorithm, the co-existence of ice- and water-phase clouds is still observed in the CALIPSO δ–γ′ relationship.
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Satellite based assessment of possible dust aerosols semi direct effect on cloud water path over east asia
2006Co-Authors: Jianping Huang, Patrick Minnis, Bing Lin, Tianhe Wang, Xin Wang, Kirk J AyersAbstract:[1] The semi-direct effects of dust aerosols are analyzed over eastern Asia using 2 years (June 2002 to June 2004) of data from the Clouds and the Earth's Radiant Energy System (CERES) scanning radiometer and MODerate Resolution Imaging Spectroradiometer (MODIS) on the Aqua Satellite, and 18 years (1984 to 2001) of International Satellite Cloud Climatology Project (ISCCP) data. The results show that the water path of dust-contaminated clouds is considerably smaller than that of dust-free clouds. The mean ice water path (IWP) and liquid water path (LWP) of dusty clouds are less than their dust-free counterparts by 23.7% and 49.8%, respectively. The long-term statistical relationship derived from ISCCP also confirms that there is significant negative correlation between dust storm index and ISCCP cloud water path (CWP). These results suggest that dust aerosols warm clouds, increase the evaporation of cloud droplets and further reduce the CWP, the so-called semi-direct effect. The semi-direct effect may play a role in cloud development over arid and semi-arid areas of East Asia and contribute to the reduction of precipitation.
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seasonal and interannual variations of top of atmosphere irradiance and cloud cover over polar regions derived from the ceres data set
2006Co-Authors: Seiji Kato, Patrick Minnis, Norman G Loeb, Jennifer A Francis, Thomas P Charlock, David A Rutan, Eugene E Clothiaux, Szedung SunmackAbstract:The semi-direct effects of dust aerosols are analyzed over eastern Asia using 2 years (June 2002 to June 2004) of data from the Clouds and the Earth s Radiant Energy System (CERES) scanning radiometer and MODerate Resolution Imaging Spectroradiometer (MODIS) on the Aqua Satellite, and 18 years (1984 to 2001) of International Satellite Cloud Climatology Project (ISCCP) data. The results show that the water path of dust-contaminated clouds is considerably smaller than that of dust-free clouds. The mean ice water path (IWP) and liquid water path (LWP) of dusty clouds are less than their dust-free counterparts by 23.7% and 49.8%, respectively. The long-term statistical relationship derived from ISCCP also confirms that there is significant negative correlation between dust storm index and ISCCP cloud water path. These results suggest that dust aerosols warm clouds, increase the evaporation of cloud droplets and further reduce cloud water path, the so-called semi-direct effect. The semi-direct effect may play a role in cloud development over arid and semi-arid areas of East Asia and contribute to the reduction of precipitation.
Timo Vihma - One of the best experts on this subject based on the ideXlab platform.
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moisture flux changes and trends for the entire arctic in 2003 2011 derived from eos Aqua data
2013Co-Authors: Linette N. Boisvert, Thorsten Markus, Timo VihmaAbstract:[1] The Arctic sea ice acts as a barrier between the ocean and lower atmosphere, reducing the exchange of heat and moisture. In recent years the ice pack has undergone many changes, in particular a rapid reduction in sea ice extent and compactness in summer and autumn. This, along with modeling studies, would cause one to believe that the moisture flux would be increasing. We estimate the daily moisture flux from 2003 to 2011 using geophysical data from multiple sensors onboard NASA's Aqua Satellite, taking advantage of observations being collected at the same time and along the same track. Our findings show the moisture flux, averaged over the entire Arctic, has had large interannual variations, with smallest fluxes in 2010, 2003, and 2004, and largest ones in 2007, 2008, and 2005. Increases in air specific humidity tend to reduce the moisture flux, whereas the decrease in sea ice cover tends to increase the flux. Statistically significant seasonal decreasing trends are seen in December, January, and February because of the dominating effect of increase in 2 m air specific humidity increasing, reducing the surface-air specific humidity difference by −0.0547 kg/kg in the Kara/Barents Seas, E. Greenland Sea, and Baffin Bay regions where there is some open water year round. Our results also show that the contribution of the sea ice zone to the total moisture flux (from the open ocean and sea ice zone) has increased by 3.6% because the amount of open water within the sea ice zone has increased by 4.3%.
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moisture fluxes derived from eos Aqua Satellite data for the north water polynya over 2003 2009
2012Co-Authors: Linette N. Boisvert, Claire L Parkinson, Thorsten Markus, Timo VihmaAbstract:Satellite data were applied to calculate the moisture flux from the North Water polynya during a series of events spanning 2003-2009. The fluxes were calculated using bulk aerodynamic formulas with the stability effects according to the Monin-Obukhov similarity theory. Input parameters were taken from three sources: air relative humidity, air temperature, and surface temperature from the Atmospheric Infrared Sounder (AIRS) onboard NASA's Earth Observing System (EOS) Aqua Satellite, sea ice concentration from the Advanced Microwave Scanning Radiometer (AMSR-E, also onboard Aqua), and wind speed from the ECMWF ERA-Interim reanalysis. Our results show the progression of the moisture fluxes from the polynya during each event, as well as their atmospheric effects after the polynya has closed up. These results were compared to results from studies on other polynyas, and fall within one standard deviation of the moisture flux estimates from these studies. Although the estimated moisture fluxes over the entire study region from AIRS are smaller in magnitude than ERA-Interim, they are more accurate due to improved temperature and relative humidity profiles and ice concentration estimates over the polynya. Error estimates were calculated to be 5.56 x10(exp -3) g/sq. m/ s, only 25% of the total moisture flux, thus suggesting that AIRS and AMSR-E can be used with confidence to study smaller scale features in the Arctic sea ice pack and can capture their atmospheric effects. These findings bode well for larger-scale studies of moisture fluxes over the entire Arctic Ocean and the thinning ice pack.
Fred G Rose - One of the best experts on this subject based on the ideXlab platform.
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a radiation closure study of arctic stratus cloud microphysical properties using the collocated Satellite surface data and fu liou radiative transfer model
2016Co-Authors: Xiquan Dong, Patrick Minnis, Shaoyue Qiu, Sunny Sunmack, Fred G RoseAbstract:Author(s): Dong, X; Xi, B; Qiu, S; Minnis, P; Sun-Mack, S; Rose, F | Abstract: © 2016. American Geophysical Union. Retrievals of cloud microphysical properties based on passive Satellite imagery are especially difficult over snow-covered surfaces because of the bright and cold surface. To help quantify their uncertainties, single-layered overcast liquid-phase Arctic stratus cloud microphysical properties retrieved by using the Clouds and the Earth’s Radiant Energy System Edition 2 and Edition 4 (CERES Ed2 and Ed4) algorithms are compared with ground-based retrievals at the Atmospheric Radiation Measurement North Slope of Alaska (ARM NSA) site at Barrow, AK, during the period from March 2000 to December 2006. A total of 206 and 140 snow-free cases (Rsfc ≤ 0.3), and 108 and 106 snow cases (Rsfcg0.3), respectively, were selected from Terra and Aqua Satellite passes over the ARM NSA site. The CERES Ed4 and Ed2 optical depth (t) and liquid water path (LWP) retrievals from both Terra and Aqua are almost identical and have excellent agreement with ARM retrievals under snow-free and snow conditions. In order to reach a radiation closure study for both the surface and top of atmosphere (TOA) radiation budgets, the ARM precision spectral pyranometer-measured surface albedos were adjusted (63.6% and 80% of the ARM surface albedos for snow-free and snow cases, respectively) to account for the water and land components of the domain of 30 km × 30 km. Most of the radiative transfer model calculated SW↓sfc and SW↑TOA fluxes by using ARM and CERES cloud retrievals and the domain mean albedos as input agree with the ARM and CERES flux observations within 10Wm-2 for both snow-free and snow conditions. Sensitivity studies show that the ARM LWP and re retrievals are less dependent on solar zenith angle (SZA), but all retrieved optical depths increase with SZA.
Frank J Wentz - One of the best experts on this subject based on the ideXlab platform.
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global microwave Satellite observations of sea surface temperature for numerical weather prediction and climate research
2005Co-Authors: Dudley B Chelton, Frank J WentzAbstract:Abstract Obtaining global sea surface temperature (SST) fields for the ocean boundary condition in numerical weather prediction (NWP) models and for climate research has long been problematic. Historically, such fields have been constructed by a blending of in situ observations from ships and buoys and Satellite infrared observations from the Advanced Very High Resolution Radiometer (AVHRR) that has been operational on NOAA Satellites since November 1981. The resolution of these global SST fields is limited by the sparse coverage of in situ observations in many areas of the World Ocean and cloud contamination of AVHRR observations, which can exceed 75% over the subpolar oceans. As clouds and aerosols are essentially transparent to microwave radiation, Satellite microwave observations can greatly improve the sampling and resolution of global SST fields. The Advanced Microwave Scanning Radiometer on the NASA Earth Observing System (EOS) Aqua Satellite (AMSR-E) is providing the first highly accurate and glob...
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high resolution Satellite measurements of the atmospheric boundary layer response to sst variations along the agulhas return current
2005Co-Authors: Larry W Oneill, Dudley B Chelton, Steven K Esbensen, Frank J WentzAbstract:Abstract The marine atmospheric boundary layer (MABL) response to sea surface temperature (SST) perturbations with wavelengths shorter than 30° longitude by 10° latitude along the Agulhas Return Current (ARC) is described from the first year of SST and cloud liquid water (CLW) measurements from the Advanced Microwave Scanning Radiometer (AMSR) on the Earth Observing System (EOS) Aqua Satellite and surface wind stress measurements from the QuikSCAT scatterometer. AMSR measurements of SST at a resolution of 58 km considerably improves upon a previous analysis that used the Reynolds SST analyses, which underestimate the short-scale SST gradient magnitude over the ARC region by more than a factor of 5. The AMSR SST data thus provide the first quantitatively accurate depiction of the SST-induced MABL response along the ARC. Warm (cold) SST perturbations produce positive (negative) wind stress magnitude perturbations, leading to short-scale perturbations in the wind stress curl and divergence fields that are li...
Linette N. Boisvert - One of the best experts on this subject based on the ideXlab platform.
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moisture flux changes and trends for the entire arctic in 2003 2011 derived from eos Aqua data
2013Co-Authors: Linette N. Boisvert, Thorsten Markus, Timo VihmaAbstract:[1] The Arctic sea ice acts as a barrier between the ocean and lower atmosphere, reducing the exchange of heat and moisture. In recent years the ice pack has undergone many changes, in particular a rapid reduction in sea ice extent and compactness in summer and autumn. This, along with modeling studies, would cause one to believe that the moisture flux would be increasing. We estimate the daily moisture flux from 2003 to 2011 using geophysical data from multiple sensors onboard NASA's Aqua Satellite, taking advantage of observations being collected at the same time and along the same track. Our findings show the moisture flux, averaged over the entire Arctic, has had large interannual variations, with smallest fluxes in 2010, 2003, and 2004, and largest ones in 2007, 2008, and 2005. Increases in air specific humidity tend to reduce the moisture flux, whereas the decrease in sea ice cover tends to increase the flux. Statistically significant seasonal decreasing trends are seen in December, January, and February because of the dominating effect of increase in 2 m air specific humidity increasing, reducing the surface-air specific humidity difference by −0.0547 kg/kg in the Kara/Barents Seas, E. Greenland Sea, and Baffin Bay regions where there is some open water year round. Our results also show that the contribution of the sea ice zone to the total moisture flux (from the open ocean and sea ice zone) has increased by 3.6% because the amount of open water within the sea ice zone has increased by 4.3%.
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moisture fluxes derived from eos Aqua Satellite data for the north water polynya over 2003 2009
2012Co-Authors: Linette N. Boisvert, Claire L Parkinson, Thorsten Markus, Timo VihmaAbstract:Satellite data were applied to calculate the moisture flux from the North Water polynya during a series of events spanning 2003-2009. The fluxes were calculated using bulk aerodynamic formulas with the stability effects according to the Monin-Obukhov similarity theory. Input parameters were taken from three sources: air relative humidity, air temperature, and surface temperature from the Atmospheric Infrared Sounder (AIRS) onboard NASA's Earth Observing System (EOS) Aqua Satellite, sea ice concentration from the Advanced Microwave Scanning Radiometer (AMSR-E, also onboard Aqua), and wind speed from the ECMWF ERA-Interim reanalysis. Our results show the progression of the moisture fluxes from the polynya during each event, as well as their atmospheric effects after the polynya has closed up. These results were compared to results from studies on other polynyas, and fall within one standard deviation of the moisture flux estimates from these studies. Although the estimated moisture fluxes over the entire study region from AIRS are smaller in magnitude than ERA-Interim, they are more accurate due to improved temperature and relative humidity profiles and ice concentration estimates over the polynya. Error estimates were calculated to be 5.56 x10(exp -3) g/sq. m/ s, only 25% of the total moisture flux, thus suggesting that AIRS and AMSR-E can be used with confidence to study smaller scale features in the Arctic sea ice pack and can capture their atmospheric effects. These findings bode well for larger-scale studies of moisture fluxes over the entire Arctic Ocean and the thinning ice pack.