Radiative transfer solution for rugged and heterogeneous scene observations

A physical algorithm is developed to solve the radiative transfer problem i n the solar reflective spectral domain. This new code, Advanced Modeling of the Atmospheric Radiative Transfer for Inhomogeneous Surfaces (AMARTIS), t akes into account the relief, the spatial heterogeneity, and the bidirectio nal reflectances of ground surfaces. The resolution method consists of firs t identifying the irradiance and radiance components at ground and sensor l evels and then modeling these components separately, the rationale being to find the optimal trade off between accuracy and computation times. The val idity of the various assumptions introduced in the AMARTIS model are checke d through comparisons with a reference Monte Carlo radiative transfer code for various ground scenes: flat ground with two surface types, a linear san d dune landscape, and an extreme mountainous configuration. The results sho w a divergence of less than 2% between the AMARTIS code and the Monte Carlo reference code for the total signals received at satellite level. In parti cular, it is demonstrated that the environmental and topographic effects ar e properly assessed by the AMARTIS model even for situations in which the e ffects become dominant. (C) 2000 Optical Society of America OCIS codes: 010 .1300, 280.0280.