Estimation of vegetation optical depth and single scattering albedo using multi-angular microwave vegetation indices (MVIs)

This paper introduces an approach for estimating vegetation optical depth and single scattering albedo using multi-angular microwave vegetation indices (MVIs). Through analysis of Advanced Integral Equation Model (AIEM) simulation database, which includes a wide range of surface roughness and soil dielectric conditions, bare soil emissivities at different incidence angles can be characterized by a linear function with parameters only dependent on the pair of incidence angles used. Based on these relationships, soil signals can be eliminated from radiometer measurements and multi-angular MVIs which are only related to vegetation parameters are derived. Then, vegetation optical depth and single scattering albedo can be estimated using radiometer measurements with multiple pairs of incidence angles. Retrievals of vegetation optical depth from Yanco Region and Little Washita watershed are compared with MODIS NDVI products.