Estimation of Soil Moisture During Winter Wheat Growing Season Based on Polarization Decomposition.

Soil moisture content (SMC) is a significant factor affecting crop growth and development. However, SMC estimation based on synthetic aperture radar (SAR) will be influenced by a variety of surface parameters, such as vegetation cover and surface roughness, which are usually difficult to measure. In order to retrieve the SMC across agricultural areas (such as wheat fields) without ground measurement. In this study, a model-based polarization decomposition method was used to decompose the original SAR signal into different scattering components representing different scattering mechanisms. Then different volume scattering models were used and compared to remove the scattering contribution from vegetation canopy, so as to extract the surface scattering component related to the soil moisture. Finally, combined with the extensively used surface scattering model (CIEM) and the method of roughness parameters optimization, the look-up table method was used to estimate the soil moisture during wheat growth period. The achieved R-2 and RMSE of the SWC are 0.534, 5.62 vol. %, which indicates that this approach has a good estimation performance on the soil moisture under wheat during its growing period.