A vegetation correction methodology applied for soil moisture retrieval from C-band radar observations

This research presents a methodology to correct backscatter (¿^o) observations for vegetation effects. The proposed methodology is based on the concept that the ratio between the surface scattering over the total amount of scattering (¿_surface ^o /¿_soil ^o) is affected only by the vegetation and can be described as a function of the vegetation water content. The data set used in this study was collected at USDA´s Optimizing Production Inputs for Economic and Environmental Enhancement (OPE³) experimental site in Beltsville, Maryland (USA) over a corn growth cycle in 2002 and includes C-band (4.75 GHz) HH- and VV-polarized observations acquired at incidence angles of 15, 35 and 55 degrees. During this period the corn crops reached peak biomass of 6.6 kg m^-2 and a soil moisture range varying from 0.02 to 0.26 cm³cm^-3. The results show that through application of the proposed vegetation correction methodology the soil moisture retrieval accuracy can be improved from 0.033 to 0.032 cm³cm^-3, 0.049 to 0.033 cm³cm^-3, and 0.079 to 0.047 cm³cm^-3 at incidence angles of 15, 35 and 55 degrees, respectively.