Extraction of atmospheric aerosol radiative characteristics for LOWTRAN7 simulation of shortwave radiation

Consideration of the radiative transfer through the atmosphere is essential for the quantitative analysis of the satellite- sensed data. To solve the radiative transfer equation directly, a detailed information about atmospheric radiation- related parameters, such as atmospheric soundings, atmospheric aerosol characteristics are required. This study presents a simple method to extract atmospheric aerosol radiative characteristics for LOWTRAN7 simulation of short wave radiation. Atmospheric aerosol radiative characteristics are obtained mainly from observed column optical depth with the statistical data of Spinhirne's atmospheric model of aerosol scattering coefficient and d'Almeida's atmospheric aerosol radiative characteristics. Also, to examine the application of this method, the results simulated by LOWTRAN7 with atmospheric aerosol radiative data are compared with CAGEX (CERES/ARM/GEWEX Experiment) data as ground-truth radiative measurements. Standard errors of LOWTRAN7's results with respect to CAGEX data were 1.9% (downward direct flux at the surface), 6.9% (downward diffuse flux at the surface). It is shown in the results that a large part of error in LOWTRAN7 flux simulation is found in the diffuse component due to scattering mainly by atmospheric aerosol. In a conclusion, better information about the radiative characteristics of atmospheric aerosols is required for improving the accuracy of radiative transfer simulation by model.