An integrated active-passive soil moisture retrieval algorithm for SMAP for bare surfaces

An integrated soil moisture retrieval algorithm is presented in this work wherein both radar and radiometer measurements are used simultaneously to retrieve surface soil moisture. This method is applied to bare rough surfaces with varying soil moisture and roughness distributions. A thresholding method based on physical models of scattering and emission is presented to obtain equivalent estimated brightness temperatures from active radar measurements. This technique is used as a constraint to link active and passive data within the optimization scheme. Numerical simulations are performed to investigate the proposed inversion technique using the method of Simulated Annealing.