A Solely Radiance-based Spectral Angular Distribution Model and Its Application in Deriving Clear-Sky Spectral Fluxes over Tropical Oceans  

作　　者：Lei SONG Yinan WANG 

机构地区：[1]Institute of Atmospheric Physics, Chinese Academy of Sciences

出　　处：《Advances in Atmospheric Sciences》2016年第2期259-268,共10页大气科学进展（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No. 41105015)

摘　　要：The radiation budget at the top of the atmosphere plays a critical role in climate research. Compared to the broadband flux, the spectrally resolved outgoing longwave radiation or flux （OLR）, with rich atmospheric information in different bands, has obvious advantages in the evaluation of GCMs. Unlike methods that need auxiliary measurements and information, here we take atmospheric infrared sounder （AIRS） observations as an example to build a self-consistent algorithm by an angular distribution model （ADM）, based solely on radiance observations, to estimate clear-sky spectrally resolved fluxes over tropical oceans. As the key step for such an ADM, scene type estimations are obtained from radiance and brightness temperature in selected AIRS channels. Then, broadband OLR as well as synthetic spectral fluxes are derived by the spectral ADM and validated using both synthetic spectra and CERES （Clouds and the Earth＇s Radiant Energy System） observations. In most situations, the mean OLR differences between the spectral ADM products and the CERES observations are within -4-2 W m-2, which is less than 1% of the typical mean clear-sky OLR over tropical oceans. The whole algorithm described in this study can be easily extended to other similar hyperspectral radiance measurements.The radiation budget at the top of the atmosphere plays a critical role in climate research. Compared to the broadband flux, the spectrally resolved outgoing longwave radiation or flux （OLR）, with rich atmospheric information in different bands, has obvious advantages in the evaluation of GCMs. Unlike methods that need auxiliary measurements and information, here we take atmospheric infrared sounder （AIRS） observations as an example to build a self-consistent algorithm by an angular distribution model （ADM）, based solely on radiance observations, to estimate clear-sky spectrally resolved fluxes over tropical oceans. As the key step for such an ADM, scene type estimations are obtained from radiance and brightness temperature in selected AIRS channels. Then, broadband OLR as well as synthetic spectral fluxes are derived by the spectral ADM and validated using both synthetic spectra and CERES （Clouds and the Earth＇s Radiant Energy System） observations. In most situations, the mean OLR differences between the spectral ADM products and the CERES observations are within -4-2 W m-2, which is less than 1% of the typical mean clear-sky OLR over tropical oceans. The whole algorithm described in this study can be easily extended to other similar hyperspectral radiance measurements.

关 键 词：hyperspectral radiance spectral angular distribution model scene type atmospheric infrared sounder 

分 类 号：P412.2[天文地球—大气科学及气象学]