Use of RADARSAT-2 data to retrieve soil moisture over bare soil agricultural fields

Soil moisture estimation is important to agricultural production. The existing inversion models based on SAR (Synthetic Aperture Radar) images are available for non-periodic surfaces but not available for periodic surfaces yet. The backscattering coefficients from periodic surfaces are not only related to SAR sensor parameters and soil surface parameters, but also related to the azimuth angle φ of crop rows. The authors analyzed the response behavior to an azimuth angle in different polarization modes. Cross-polarization (VH) showed no dependence on φ, yet like-polarization (HH or VV) showed sensitive behavior to φ, and then the authors provided the response functions. Furthermore, the authors built a parameter to remove the influence of φ and established an inversion model of soil moisture for periodic surfaces. Lastly, they proved the validity by field data.