CARE product:Cloud microphysics and shortwave radiation forcing algorithms and applications
The accurate acquisition of cloud microphysical parameters,Cloud Optical Thickness(COT),and Cloud Effective Radius(CER),is crucial to the calculation of surface or Top-Of-Atmosphere(TOA)radiation budget.However,most of the studies consider little about the cloud phase.Even if the cloud phase state is considered,the ice cloud is assumed to be spherical,which brings errors to the subsequent radiation calculation.In addition,only a few studies focus on cloud shortwave radiation forcing(SWRF)from satellites,but on downward shortwave radiation at the surface.To solve above problems,this study proposes methods for retrieving COT and CER for water and ice clouds as well as estimation of SWRF from the Himawari-8 satellite.In this study,we proposed a novel method for the retrieval of COT and CER for water and ice clouds from the new-generation geostationary satellite Himawari-8 measurements on the basis of the radiative transfer theory and optimal method.The irregularly shaped model named Voronoi,which was widely used in Japan Aerospace Exploration Agency satellite missions,such as Himawari-8,GCOMC-C,was used in our ice cloud model.In addition,a method for estimation of SWRF at the surface and the TOA was proposed on the basis of the look-up table(calculated by the radiative transfer model-RSTAT)method,as inputs of retrieved COT and CER above.Finally,the retrieved COT and CER from Himawari-8 in this study were validated with moderate-resolution imaging spectroradiometer(MODIS)collection-6(C6)cloud product and an estimated SWRF from Himawari-8 by this study with Clouds and the Earth's Radiant Energy System(CERES)level-3(L3)SYN product,respectively.Validation with MODIS C6 cloud product for 4 days in different seasons(2016-01-01,2016-04-01,2016-07-01,2016-10-01)shows that our retrieved COT and CER for water and ice clouds from Himawari-8 have a good agreement with the MODIS product,with correlation coefficient(R)values of COT of 0.68 and 0.77,respectively.For CER,the different ice cloud model used in MODIS and this study show a lower R value.For validation of SWRF with the CERES L3 SYN product,the estimated SWRF at the surface and the TOA by this study show good agreement,with R values of 0.97 and 0.98,root mean square error values of 15.0 and 16.6 Wm2.While,mean bias error(MBE)values of-5.6 Wm-2 and-8.5 Wm-2 indict that our SWRF results having a slight underestimation.Our proposed methods for retrieving COT and CER,as well as SWRF at the surface and the TOA from Himawari-8,are effective.Although our ice cloud model(Voronoi)is different with MODIS,the finial SWRF validation still shows that our cloud products have high accuracy in other aspects.This research can provide important reference for the subsequent full radiation budget(shortwave plus longwave)estimation.Detailed products are available in our homepage(http://www.slrss.cn/care zh/[2022-08-31]).
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维普
