A polarimetric two-scale model for soil moisture retrieval

A polarimetric two-scale surface scattering model employed to retrieve the surface parameters of bare soils from polarimetric SAR data is proposed. The scattering surface is considered as composed of slightly rough randomly tilted facets, for which the Small Perturbation Method holds. The facet random tilt causes a random variation of the local incidence angle, and a random rotation of the local incidence plane around the line of sight, which in turn causes a random rotation of the facet scattering matrix. Unlike other similar already existing approaches, our method considers both these effects. The proposed scattering model is then used to retrieve bare soil moisture and (large-scale) roughness from the co-polarized and cross-polarized ratios. The performances of the resulting retrieval algorithm is finally assessed by comparing obtained results to “in situ” measurements. To this aim, data from Little Washita campaign available in literature is employed.