Oil spill detection using a time series of images acquired off Norway in June 2015 with the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is examined. The relative performance of a set of features derived from quad- polarization vs. hybrid-polarity modes in detection of various types of slicks as they evolve on a high wind driven sea surface is evaluated. It is shown that the hybrid-polarity mode is comparable to the full-polarimetric mode in its ability to distinguish the various slicks from open water for challenging conditions of high winds (9-12 m/s), small release volumes (0.2 – 0.5m3), and during the period 0-9 hours following release. The features that contain the cross-polarimetric component are better for distinguishing the various slicks from open water at later and more developed stages. Although these features are not available in the hybrid-polarity mode, we identify alternative features to achieve similar results. In addition, a clear correlation between the results of individual features and their dependence on particular components within the two-scale Bragg scattering theory is identified. The features that show poor detectability of the oil slicks are those that are independent of the small-scale roughness, while the features resulting in good separability were dependent on several factors in the two-scale Bragg scattering model. We conclude that the hybrid-polarity mode is a viable alternative for SAR-based oil spill detection and monitoring that provides comparable results to those from quad-polarimetric SAR.
Espeseth et al. (2017) Analysis of Evolving Oil Spills in Full-Polarimetric and Hybrid-Polarity SAR. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, March 2017. (Accepted)