Retrieval Methods of Aerosol Optical Parameters using POLDER Data

Abstract

In the previous studies aerosol's optical thickness and Ångström exponent were retrieved from the satellite measured reflectance data by assuming pre-fixed complex refractive index of aerosol. In this study, for the first time, we estimated aerosol's real part of complex refractive index, together with its optical thickness and Ångström exponent from the directional reflectance and polarization data measured by POLDER on board ADEOS satellite by three different retrieval methods, namely, RP-Method, RR-Method, and PP-Method. RP-Method uses both directional reflectance and linear polarization values in a single infrared band. On the other hand, RR-and PP-Methods use directional reflectance and linear polarization values in two infrared bands, respectively. We found that RP-Method gives the best results in comparison with sky observation data at our study site, synchronized with the overflight of ADEOS. Finally, we presented the retrieved distribution maps of aerosol's three optical parameters over the Japan Sea and the western part of the Pacific Ocean by RP-Method.