BRDF Effects in Satellite Retrieval of Surface Spectral Reflectance in Solar Spectral Region

Surface reflectance/albedo is important for many geophysical applications, atmospheric circulation, and climate modeling (Henderson-Sellers et al. 1993). It is a key input parameter for land type classification and serves as a major boundary condition in surface-atmosphere radiative transfer modeling, which determines the distribution of solar energy between the surface and the atmosphere. Surface reflective properties can be retrieved from satellite observations. A surface target may be observed by satellite from different viewing directions. Due to the anisotropy of surface reflection, this leads to diversity of surface properties retrieved from satellite composite images (Li et al. 1996). To address this problem, one needs to determine the surface bidirectional reflectance distribution function (BRDF) properties and correct for them in the final product. Integrals of BRDF functions result in the so-called black-sky and white-sky albedos that convey important information concerning the inherent properties of surface albedo (Wanner et al. 1997).