Soil Parameter Retrievals Over Bare Agricultural Fields Using Multiangular RADARSAT-2 Dataset

The objective of this study is to evaluate the potential of multiangular SAR data at C-band for soil parameters' discrimination over bare agricultural fields. In order to exploit the incidence angle diversity to enhance the soil parameter retrievals, the conventional multiangular roughness descriptor Δ_HH formulated originally as the backscattering difference between two specific incidence angles is adapted to take into account a general incidence angle effect. Moreover, a new angular coherence SAR descriptor γ_HH is proposed by using a pair of low and high incidence angle SAR data. The adapted Δ_HH and the proposed γ_HH are applied to the RADARSAT-2 data with three different incidence angles. The results indicate that the proposed γ_HH is more sensitive to surface roughness than the adapted Δ_HH. Thus, the γ_HH is selected to retrieve the surface roughness, and then the retrieved surface roughness is substituted into a low incidence angle data to retrieve the soil moisture. The RMSE of 6.1-8.5 m³/m³ is obtained for soil moisture retrieval.