ESTIMATING SURFACE REFLECTANCE AND ALBEDO FROM LANDSAT-5 THEMATIC MAPPER OVER RUGGED TERRAIN

A model for estimating surface reflectance and albedo from satellite radiance measurements over rugged terrain is presented. Using a two-stream radiative transfer model, direct and diffuse sky irradiance as well as path radiance and atmospheric transmission are calculated for a horizontally homogeneous atmosphere. A digital elevation model is used to estimate these parameters for surfaces of varying elevation, slope, and aspect. The satellite- derived, corrected reflectance measurements obtained from Landsat Thematic Mapper Bands 2, 4, and 7 are integrated into a measure of albedo by the use of a weighted average scheme which takes into account the spectral reflectivity of the surface of interest as well as the spectral distribution of total shortwave irradiance. The model is then tested over an area in the east slope of the Colorado Front Range. Estimated values of albedo for selected surfaces in the alpine tundra are in substantial agreement with published data for comparable surfaces and field measurements in the region.