Algorithm description of system flow for global aerosol distribution

摘要

This paper describes a processing flow to extract aerosol characteristics on a global scale from polarization and directionality of Earth reflectance (POLDER) level 1 data. POLDER provides radiance and polarization in the visible and near-infrared regions. Our procedure is composed of two phases; one is a data reduction process from the POLDER level 1 to the global scale, and the other is the aerosol retrieval process. The retrieval algorithm is achieved in practice using a look-up table which is compiled based on multiple scattering simulations in an atmosphere–sea surface system. Monthly global distribution maps showing the Ångström exponent and the optical thickness of aerosols were obtained in November 1996 and in January and April 1997. From these aerosol maps, it can be seen that: (1) the aerosol distribution derived from POLDER radiance and polarization data coincides with the radiance data obtained independently from OCTS, (2) atmospheric aerosols exhibit certain intrinsic feature on a global and on a seasonal scale.