RETRIEVAL OF AEROSOL OPTICAL-PROPERTIES FROM MULTI-ANGLE SATELLITE IMAGERY

Optical properties of tropospheric aerosols, such as their opacity, single-scattering albedo, and phase function are needed for studies of their effects on the solar radiation budget at the Earth's surface and as input to surface reflectance retrieval algorithms designed to correct top-of-atmosphere imagery for atmospheric effects. Using simulation multi-angle imagery, we have been investigating a new method for retrieving atmospheric aerosol optical properties over land. The described method makes use of the presence of spatial contrasts within the imagery, and compares the spatial Fourier transforms of the multi-angle images at zero and nonzero spatial frequencies. An initial guess for the aerosol properties is made and the Fourier components of the surface reflectance distribution are retrieved at zero and nonzero frequencies. A comparison of the angular shape of the retrieved functions is then used to establish whether the initial guess for the aerosol parameters was correct. Other than the need to define a relationship between the angular variation of the Fourier transform of the intrinsic surface angular reflectance at the zero and nonzero frequencies, the method assumes no a priori knowledge about the aerosols or surface characteristics. We discuss sensitivities to various aerosol properties.