This article is devoted to investigating the microwave scattering mechanisms of oil-free and oil-covered sea surfaces for an incidence angle smaller than 30° in a backscattering configuration. The Elfouhaily spectrum is used to simulate an oil-free sea surface, whereas the Elfouhaily spectrum combined with the Jenkins damping model is applied to the simulation of an oil-covered sea surface. Then, the Kirchhoff approximation-stationary phase approximation (KA-SP) and the first order of small-slope approximation (SSA-1) are employed to simulate the scattering coefficients induced by specular scattering and total scattering, respectively. Importantly, a new parameter defined as specular scattering to total scattering ratio (STR) is proposed in this article, which can be used to measure the ratio of specular backscattered power to total backscattered power. The dependencies of the scattering coefficient and the STR on incidence angles, wind speeds, wind directions, oil thicknesses, and so on, are investigated. This article provides new insights for a better understanding of the evolution of microwave scattering mechanisms from oil-free and oil-covered sea surfaces in the transition region of incidence angles (from about 15° to 30°).

中文翻译：

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入射角小于30°的有油膜和无油膜覆盖的海面微波散射机理的理论研究

本文专门研究在反向散射配置中入射角小于30°的无油和被油覆盖的海面的微波散射机理。Elfouhaily谱用于模拟无油海面，而Elfouhaily谱与Jenkins阻尼模型结合用于模拟含油海面。然后，分别采用基尔霍夫近似平稳相位近似（KA-SP）和一阶小斜率近似（SSA-1）来模拟由镜面散射和总散射引起的散射系数。重要的是，本文提出了一个新参数，定义为镜面散射与总散射比（STR），可以用来测量镜面后向散射功率与总后向散射功率之比。研究了散射系数和STR对入射角，风速，风向，油层厚度等的依赖性。本文为更好地了解入射角过渡区域（约15°至30°）中无油和被油覆盖的海面的微波散射机制的演变提供了新的见解。