Development of a simple scattering model for radar backscatters of agricultural fields to be used in retrieving soil moisture

This paper presents the development of an accurate and simple scattering model for radar backscatters of agricultural fields using the water-cloud model (WCM) and the first-order radiative transfer (RT) model. This new model is accurate and simple enough to be used for soil moisture retrieval from the measured backscattering coefficients of vegetation fields. To improve the accuracy of the scattering model, we modified the WCM with an additional term for accurately estimating the angular effect of scattering particles in a vegetation canopy, using the relatively accurate first-order RT model. The accuracy of the scattering model was verified with the COSMO SkyMed radar data and ground-truth in-situ measurements of a bean field and a wheat field. The simple model was applied to retrieve soil moisture from the radar measurements. The estimated soil moisture contents agree well with the in-situ measured soil moisture contents for the bean and wheat fields with the correlation coefficients of 0.91 and 0.96, respectively.