This paper is devoted to the forward radar propagation over clean and contaminated seas, using the Ament model and by taking the shadowing effect into account. The well-known Rayleigh parameter, which characterizes the degree of roughness of a corrugated surface for the case of reflection on a rough surface, is presented. Then, it is extended to the transmission through a rough surface, and to the reflection on a layer of two rough interfaces. This extended Rayleigh parameter allows then to calculate the forward radar propagation over oil slicks on sea surfaces, using the Ament model. Moreover, the model is improved by taking the shadowing effect into account. Numerical results of contaminated seas are presented, and compared to that of clean seas.
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