Polarimetric decomposition of multi-angular SAR data for soil moisture retrieval over agricultural fields

This study investigates the polarimetric decomposition of multi-angular polarimetric UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) time series, for soil moisture retrieval over the vegetated agricultural fields. The volume scattering component was respectively removed from different incidence angle data. The resulting multiple dominant surface or dihedral scattering components were then integrated as a multi-angular cost function, from which the soil moisture was retrieved. The retrieval performances of single-angular and multi-angular methods were compared, and validated with the ground measurements. The results indicated that, due to the incidence angle combination, the retrieval RMSE decreased, and the level depends on the phenological stage. A significantly high retrieval rate of 90% can be obtained by the multi-angular approach, compared to that of 50% in the single-angular method.