Standalone SAR Soil Moisture Retrieval Using Radar Vegetation Indices

In this paper, we present a methodology for retrieving soil moisture using radar-derived vegetation parameters from multi-polarization SAR data. The semi-empirical Water Cloud Model (WCM) is used to retrieve soil moisture in wheat cropping fields. The ground and airborne data collected during the Soil Moisture Active Passive Validation EXperiment 2012 (SMAPVEX12) are used for this study. In a comparison of the two vegetation descriptors used in the WCM, the Radar Vegetation Index (RVI) and Dual-pol Radar Vegetation Index (DpRVI), the DpRVI in VH polarisation provides greater retrieval accuracy with an RMSE of 0.047 m ³ m ⁻³ and Pearson’s correlation coefficient (R) of 0.83. Our results also indicate that HH polarization outperforms the VV polarization for the wheat crop.