Assessment of the RISAT-1 FRS-2 mode for oil spill observation

Synthetic aperture radar data acquired by the Radar Imaging Satellite (RISAT-1) over experimental oil spills is here investigated. One quad-polarization scene in the Fine Resolution Alternate Polarization Stripmap (FRS-2) mode is analyzed to evaluate the potential of using this mode for oil spill observation. Oil slicks of varying type and age are clearly detected in the HH and VV channels, with relatively high signal-to-noise ratios. The cross-polarization channel is not found useful due to its proximity to the noise floor and some processing issues in the received product. Only intensity-based multipolarization parameters can be extracted due to the incoherent data acquisition. The Total Copolarization Power and the Polarization Difference are found to have good detection capabilities, whereas the Copolarization Power Ratio and the Normalized Polarization Difference only show small indications of the slicks. Comparison between SAR data and coincident observations from aircraft show a correlation between enhanced SAR signatures and locations of thicker oil layers.