A SIMPLE APPROACH TO ESTIMATE LAND SURFACE ALBEDO FROM SATELLITE MEASUREMENTS

摘要

In this study, the POLarization and Directionality of the Earth's Reflectance (POLDER-1) bidirectional reflectance distribution function (BRDF) database, which is produced and distributed by Medias-France, are used to estimate surface spectral albedo. Except for the cover types of water bodies and snow-ice, fifteen out of a total seventeen International Geosphere Biosphere Programme (IGBP) land cover types are analyzed one by one, month-by-month, An optimal viewing angle is found at the back scattering direction, and its corresponding reflectance, the so-called hot spot is extracted from each pixel in the BRDF database. An empirical model is built for estimating the spectral albedo from the corresponding hot spot directional reflectance. The most interesting thing is that beyond the expectations, the hot spot-albedo relations appears almost in the same shape, no matter the type of variation of the surface cover and its seasonal change. This method can be used for instantaneous inference of surface albedo at global scale in the case of hot spot information exists. For more convenient applications for other viewing angles of the satellite measurements, further studies are needed.