Soil permittivity estimation over vegetative fields using dual polarimetric SAR data

Abstract

Soil permittivity estimation using Synthetic Aperture Radar (SAR) data under the vegetation cover has been an extensive research domain. In particular, the vegetation canopy over the soil layer complicates the interaction of microwave signals with the underneath soil layer and the vegetation canopy geometry. Nevertheless, the sensitivity of the microwave signal with the target dielectric and geometric properties makes it possible to retrieve the target permittivity from the SAR data. This work proposes a methodology for retrieving soil permittivity using dual-polarimetric (HH-HV or VV-VH) SAR data. We first derive the 2 × 2 covariance matrix (CXX-XYXB) for the extended Bragg (X-Bragg) surface scattering for both HH-HV and VV-VH configurations. The X-Bragg covariance information inherently captures the soil surface condition. Finally, we utilize the existing scattering power factorization framework to retrieve soil permittivity. We have validated the efficacy of the proposed technique using the simulated NISAR product from the L-band UAVSAR data over Manitoba, Canada, and the C- and L- band ESAR data over DEMMIN, Germany. The proposed technique achieves the soil permittivity within a Root Mean Square Error (RMSE) range of 2 to 6 for HH-HV and VV-VH configurations.