Assessing the coupling between surface albedo derived from MODIS and the fraction of diffuse skylight over spatially-characterized landscapes

摘要: Abstract In this effort, the MODerate Resolution Imaging Spectroradiometer (MODIS) (Collection V005) Bidirectional Reflectance Distribution Function (BRDF)/Albedo algorithm is used to retrieve instantaneous surface albedo at a point in time and under specific atmospheric conditions. These retrievals are then study role that fraction of diffuse skylight plays realistic scenarios anisotropic illumination multiple scattering between atmosphere. Simulations sky radiance using MODTRAN®5.1 radiative transfer model were performed different aerosol optical properties, conditions, characteristics describe these effects on from MODIS. This technique was examined validation scheme over four measurement sites with varied levels landscapes, ranging croplands tundra ecosystems, extended periods. Furthermore, series geostatistical analyses examine types spatial patterns observed each site. particular, Enhanced Thematic Mapper Plus (ETM+) acquired analyze change variogram parameters as function increased window-size. Results assess degree which given able capture intrinsic variability scale MODIS observations. Assessments albedos account for scattering, snow-free snow-covered lands all diurnal solar zenith angles, show slight improvement formulations treat downwelling radiation isotropic. Comparisons field measurements biases improving by 0.004–0.013 absolute units (root-mean-squared error) or 0.1%–2.0% relative error.