Dual Antenna Space-Based GNSS-R Ocean Surface Mapping: Oil Slick and Tropical Cyclone Sensing
A technique to sense sea surface features using the reflections from Global Navigation Satellite System (GNSS) satellites is presented in this paper, in which a novel method for compensating the distortions induced during the delay-Doppler map (DDM) deconvolution process of scattering coefficient retrieval is proposed. A distortion distribution generated using a clean ocean surface is used as a baseline for the inaccuracy due to the constrained least square (CLS) filter. This baseline distribution is used to correct the CLS distortions of “deblurred” DDMs generated from various ocean surface conditions. Subsequently, a spatial integration approach (SIA) is applied to retrieve the scattering coefficients unambiguously using the DDMs obtained by two separate antenna beams. Additionally, the proposed technique is then applied to oil slick detection and cyclone mapping. A performance characterization including retrieval accuracy and resolution is demonstrated with respect to wind speed (WS), oil slick size, and cyclone location. Various simulations show that the retrieval error can be reduced by the SIA after the distortion correction. The technique proposed here can be applied generically to produce physical surface maps of the bistatic scattering coefficient from multiple DDMs from a single space-based platform.