Numerical experiments on the spatial scaling of land surface albedo and leaf area index

Abstract

Understanding the spatial scaling of land surface albedo and leaf area index (LAI) over heterogeneous landscapes has the practical implications to algorithm development, validation and applications of satellite products. In this study, we designed the numerical experiments to evaluate whether the retrieved LAI values from coarse-resolution satellite imagery are equivalent to the ground "true" values, and to test whether the spectral BRDF and albedos can be linearly scaled from the fine resolutions to the coarse resolutions. These numerical experiments were conducted by using both three-dimensional atmospheric and canopy radiative transfer models. The results based on the summer Landsat Thematic Mapper data over the US Department of Agriculture (USDA) Beltsville Agricultural Research Center (BARC) Remote Sensing Validation Site showed that the BRDF and albedo scaling is quite linear, and the retrieved LAI values could be quite different from the true LAI values if the surface is highly heterogeneous.