SAR raw signal simulation of oil slicks in ocean environments

Abstract—Synthetic aperture radar (SAR) raw signal simula-tion is a powerful tool for design of oil slick detection and inter-pretation systems. In this paper, the ocean simulation issues are presented, and the main problems relating to the oil presence on the sea surface are treated. Attention is focused on the electromag-netic side of the problem, with care to the sensor signatures, the dielectric, physical–chemical, and geometric nature of the oil slick, and to the environmental conditions. The presented SAR simulator is based on an ocean model and an oil slick model. The former makes use of multiscale description of the ocean surface: the dis-tributed surface model for the SAR–ocean interaction is considered by taking into account the nonlinear hydrodynamic effect for the water particle movement. The latter model implements a modifica-tion of the ocean spectrum, based on the Marangoni theory and ac-counting for the nonlinear wave interaction mechanism. However, the proposed SAR raw signal simulator is modular and flexible, thus allowing other possible physical models for modeling the oil slick effect over the ocean spectrum. Meaningful SAR simulation experiments are presented and discussed, elucidating the role of difference on pollutants, oil thickness, wind speed and direction, incident wavelength and angle and other radar parameters. Vali-dation of the simulator is also presented by comparison with exper-imental data. A striking conclusion of the paper is that higher order moments (from the second on) of oil slick SAR image statistics are quite different compared to those pertinent to an equivalent wind speed decrease on the imaged area. This suggests a convenient way to define new appropriate oil slick signatures. Index Terms—Oceans, sea surface electromagnetic scattering, simulation, synthetic aperture radar (SAR), water pollution. I