A new algorithm to determine the spectral aerosol optical depth from satellite radiometer measurements

A new aerosol retrieval algorithm is presented which computes the spectral optical depth over the ocean from spaceborne radiometers. It includes both multiple scattering and the bi-directional reflectance of the ocean surface. The algorithm is applied to data from the Along Track Scanning Radiometer 2 (ATSR-2). This radiometer aboard the ERS-2 satellite has 4 bands in the visible and near-infrared. The ATSR-2 has a dual view capability: the reflectance is measured both at nadir and at a forward angle of approximately 55° along track. This feature is used to test the algorithm by comparing independent retrievals from the forward and the nadir view, applied to Southern Hemisphere data from 23 July 1995. The retrieved aerosol optical depths compare favorably. The retrieved aerosol optical depths and spectral behavior are in agreement with expected values in clean marine environments.