Accuracy Assessment of IWCM Soil Moisture Estimation Model in Different Frequency and Polarization Bands

Abstract

Radar backscattering coefficient has high dependence to dielectric constant of soil and many efforts have been done in the past to estimate soil moisture using Synthetic Aperture Radar (SAR). Soil moisture estimation in vegetated areas has some limitations and difficulties due to the effects of vegetation cover and soil surface roughness on radar backscattering coefficient. One of the widely used soil moisture estimation models in vegetated areas is Water Cloud Model (WCM) which has been improved and known as Improved Water Cloud Model (IWCM) recently. One way of improving soil moisture estimation accuracy in vegetated areas is to use optimum frequency and polarization band so as to minimize the effects of soil surface roughness and vegetation cover on radar back scattering coefficient. In this research, the accuracies of IWCM in different frequencies and polarizations have been assessed. The results showed that the IWCM has its highest accuracy in L-band, HV polarization mode. Also, by using the IWCM, sensitivities of radar waves to moisture of 0–3, 3–6 and 0–6 cm soil depths have been studied. The results demonstrated that radar waves have more sensitivity to the moisture content of 0–3 cm soil depth.