Perturbation Technique to Retrieve Scattering Medium Stratification

Abstract

It is well known that optical satellite remote sensing is mostly based on measurements of the radiance exiting the top of the earth's atmosphere and is interpreted using a comparison of the data with precalculated tables for some ?pure? aerosol models. However, such an approach seems to meet some difficulties connected to both the necessity to search in the multidimensional parameter space and to increase the volume of the precalculated database, if the number of basic aerosol components increases. This problem becomes more real now because modern satellite sensors [multiangle imaging spectroradiometer (MISR), Polarization and Directionality of the Earth's Reflectances (POLDER)] provide more information by performing multiangle radiance measurements over the same pixel and more detailed characteristics of the atmospheric aerosol profile (not only the aerosol optical depth and Ångström coefficient) are expected to be retrieved. Recently, it has been shown that the perturbation technique was an ideal tool to solve such atmospheric physics problems as an investigation of the effect of a variation in aerosol profile on fluxes. Moreover, it has shown its efficiency in analysis of the optical remote sensing in the simplest case of the sounding of a homogeneous medium. In the present paper the perturbation technique is applied to a realistic atmosphere?ocean model. Simulations were performed for a stratified slab medium with an underlying surface. Perturbations considered include variations of the profiles of extinction coefficient and single scattering albedo, and also the adding of a small cloud contamination. It was shown that the perturbation technique allows one to predict the effect of such variations of the atmospheric profile to the exiting radiance with high accuracy. The nature of the errors is analyzed and discussed.