TOPOGRAPHIC DEPENDENCE OF SYNTHETIC-APERTURE RADAR IMAGERY

The increasing availability of synthetic aperture radar (SAR) remote-s ensing imagery for earth-science applications creates the need for rel iable computer methods to improve the relationships between SAR observ ations and the Earth's abiotic, biotic, and cultural resources. In thi s paper, the topographic effect on aerial and satellite SAR imagery is quantified and corrected using software modified from an earlier norm alized-cosine package written for use with optical/infrared remote-sen sing imagery. The basic idea is that the incidence angle and forest ca nopy interactions with the radar beam can be estimated using a digital elevation model (DEM) and near-coincident observations in the red and near-infrared portions of the spectrum. Four different study areas in Canada and three different types of SAR imagery are used to illustrat e the topographic dependence; and the degree of accuracy that;can be e xpected, following the application of these relatively simple radiomet ric corrections.