New parameters in compact polarimetry for ocean target detection

In this paper, we develop three new parameters for compact polarimetry to a particular application in synthetic aperture radar (SAR) maritime surveillance, i.e., the joint oil-spill and ship detection. Based on the X-Bragg rough surface scattering model, we investigate the capability of compact polarimetry, a dual-polarized system, for sea surface scattering characterization, and find that the circular-transmit-and-linear-receive (CTLR) mode has a better potential for sea surface representation. Then three parameters are used to discriminate the target scattering properties at sea. These parameters allow distinguishing oil spills from two kinds of look-a-likes, i.e., biogenic slicks and low-wind areas, and show good performance for ship detection. In addition, by investigating the relationship between the elements in CTLR mode and full-polarized mode, it is shown that in the simple scenario of sea surfaces, the three parameters have their approximations in the full-pol mode. The mutual related parameters (i.e., the proposed parameters in the CTLR mode and the corresponding approximations in the FP mode) have SAR signatures very similar to each other. At last, several polarimetric data sets, including Radarsat-2 C-band data, UAVSAR L-band data and SIR-C/X-SAR C-band data are studied for verification and demonstration.