Satellite Dual-Polarization Radar Imagery Superresolution Under Physical Constraints

A novel physically justified method for spatial resolution enhancement of satellite dual-polarization synthetic aperture radar data is proposed. The method starts from the conversion of the specific land surface radar backscattering into the land surface dielectric permittivity in each polarization band separately. Said conversion is founded on a well-known integral equation model of synthetic aperture radar (SAR) backscattering. Transition from raw radar data to dielectric permittivity forms a common unified image field in each polarization band. Due to the SAR platform’s own movement, these fields are affected by some subpixel shift to each other. So, the opportunity to apply the superresolution technique over all permittivity fields at once is enabled with considering ones’ subpixel shift. Dual-image iterative superresolution based on Gaussian regularization was used. A standalone software module for statistical estimation of inter-images subpixel shift was developed earlier and applied in current research. A noticeable spatial resolution enhancement of the land surface dielectric permittivity field was achieved. This was demonstrated and quantified for actual dual-polarization radar images from the Sentinel-1 European SAR satellite system over two test sites in Ukraine.