Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds
Abstract General circulation models (GCMs) are extensively used to estimate the influence of clouds on the global energy budget and other aspects of climate. Because radiative transfer computations involved in GCMs are costly, it is typical to consider only absorption but not scattering by clouds in...
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American Geophysical Union (AGU)
2017-12-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1002/2017MS001117 |
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| author | Chia‐Pang Kuo Ping Yang Xianglei Huang Daniel Feldman Mark Flanner Chaincy Kuo Eli J. Mlawer |
| author_facet | Chia‐Pang Kuo Ping Yang Xianglei Huang Daniel Feldman Mark Flanner Chaincy Kuo Eli J. Mlawer |
| author_sort | Chia‐Pang Kuo |
| collection | DOAJ |
| description | Abstract General circulation models (GCMs) are extensively used to estimate the influence of clouds on the global energy budget and other aspects of climate. Because radiative transfer computations involved in GCMs are costly, it is typical to consider only absorption but not scattering by clouds in longwave (LW) spectral bands. In this study, the flux and heating rate biases due to neglecting the scattering of LW radiation by clouds are quantified by using advanced cloud optical property models, and satellite data from Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Clouds and the Earth's Radiant Energy System (CERES), and Moderate Resolution Imaging Spectrometer (MODIS) merged products (CCCM). From the products, information about the atmosphere and clouds (microphysical and buck optical properties, and top and base heights) is used to simulate fluxes and heating rates. One‐year global simulations for 2010 show that the LW scattering decreases top‐of‐atmosphere (TOA) upward flux and increases surface downward flux by 2.6 and 1.2 W/m2, respectively, or approximately 10% and 5% of the TOA and surface LW cloud radiative effect, respectively. Regional TOA upward flux biases are as much as 5% of global averaged outgoing longwave radiation (OLR). LW scattering causes approximately 0.018 K/d cooling at the tropopause and about 0.028 K/d heating at the surface. Furthermore, over 40% of the total OLR bias for ice clouds is observed in 350–500 cm−1. Overall, the radiative effects associated with neglecting LW scattering are comparable to the counterpart due to doubling atmospheric CO2 under clear‐sky conditions. |
| format | Article |
| id | doaj-art-e078e6515f6a4ecda2ff38a6d926986a |
| institution | OA Journals |
| issn | 1942-2466 |
| language | English |
| publishDate | 2017-12-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-e078e6515f6a4ecda2ff38a6d926986a2025-08-20T02:33:11ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662017-12-01983082309810.1002/2017MS001117Impact of Multiple Scattering on Longwave Radiative Transfer Involving CloudsChia‐Pang Kuo0Ping Yang1Xianglei Huang2Daniel Feldman3Mark Flanner4Chaincy Kuo5Eli J. Mlawer6Department of Atmospheric SciencesTexas A&M UniversityCollege Station TX USADepartment of Atmospheric SciencesTexas A&M UniversityCollege Station TX USADepartment of Atmospheric, Oceanic, and Space SciencesUniversity of MichiganAnn Arbor MI USALawrence Berkeley National LaboratoryBerkeley CA USADepartment of Atmospheric, Oceanic, and Space SciencesUniversity of MichiganAnn Arbor MI USALawrence Berkeley National LaboratoryBerkeley CA USAAtmospheric and Environmental Research, IncCambridge MA USAAbstract General circulation models (GCMs) are extensively used to estimate the influence of clouds on the global energy budget and other aspects of climate. Because radiative transfer computations involved in GCMs are costly, it is typical to consider only absorption but not scattering by clouds in longwave (LW) spectral bands. In this study, the flux and heating rate biases due to neglecting the scattering of LW radiation by clouds are quantified by using advanced cloud optical property models, and satellite data from Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Clouds and the Earth's Radiant Energy System (CERES), and Moderate Resolution Imaging Spectrometer (MODIS) merged products (CCCM). From the products, information about the atmosphere and clouds (microphysical and buck optical properties, and top and base heights) is used to simulate fluxes and heating rates. One‐year global simulations for 2010 show that the LW scattering decreases top‐of‐atmosphere (TOA) upward flux and increases surface downward flux by 2.6 and 1.2 W/m2, respectively, or approximately 10% and 5% of the TOA and surface LW cloud radiative effect, respectively. Regional TOA upward flux biases are as much as 5% of global averaged outgoing longwave radiation (OLR). LW scattering causes approximately 0.018 K/d cooling at the tropopause and about 0.028 K/d heating at the surface. Furthermore, over 40% of the total OLR bias for ice clouds is observed in 350–500 cm−1. Overall, the radiative effects associated with neglecting LW scattering are comparable to the counterpart due to doubling atmospheric CO2 under clear‐sky conditions.https://doi.org/10.1002/2017MS001117longwave scatteringradiative effect of cloudsradiative transferdoubling CO2outgoing longwave radiationsimulation biases |
| spellingShingle | Chia‐Pang Kuo Ping Yang Xianglei Huang Daniel Feldman Mark Flanner Chaincy Kuo Eli J. Mlawer Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds Journal of Advances in Modeling Earth Systems longwave scattering radiative effect of clouds radiative transfer doubling CO2 outgoing longwave radiation simulation biases |
| title | Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds |
| title_full | Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds |
| title_fullStr | Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds |
| title_full_unstemmed | Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds |
| title_short | Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds |
| title_sort | impact of multiple scattering on longwave radiative transfer involving clouds |
| topic | longwave scattering radiative effect of clouds radiative transfer doubling CO2 outgoing longwave radiation simulation biases |
| url | https://doi.org/10.1002/2017MS001117 |
| work_keys_str_mv | AT chiapangkuo impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds AT pingyang impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds AT xiangleihuang impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds AT danielfeldman impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds AT markflanner impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds AT chaincykuo impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds AT elijmlawer impactofmultiplescatteringonlongwaveradiativetransferinvolvingclouds |