Research Of Electromagnetic Scattering From A Polluted Sea Surface

As the rise of offshore oil exploitation and transport, oil spills have repeatedly occurred. Significant damage to the marine environment and huge losses of marine economy can be caused by oil slicks. SAR(Synthetic Aperture Radar) is an effective means of monitoring the oil spill. Oil spill will change the physical and geometrical properties of sea surface, causing attenuation of capillary wave and the Bragg scattering, so that the area of oil spill presents dark in SAR image. But many other phenomena(such as internal waves, biological film, low wind speed area) in the SAR image is also showing a dark area. Therefore, it is necessary to quantitative research on the electromagnetic scattering from the sea surface covered by oil film.The attenuation of the EM scattering from the sea surface, caused by oil spills, is the main content of this paper. Therefore, in this paper, we will firestly study the attenuation of the wave spectrum,which is the basis for calculating electromagnetic scattering from sea sueface. We study the influence of the oil films on the action balance equation。The energy input by wind, non-linear wave interaction, energy loss by viscosity and energy loss by wave breaking were taken into account.A damping model is established for quantitative description of modulation of the spectrum when the surface is covered by oil slicks. In this process, we pay close attention to the impact of the physical parameters of the oil film and wind speed.The clean sea is described by Elfouhaily wave spectrum, we can get contaminated sea spectrum by using the established oil spill damping model and Elfouhaily wave spectrum. The composite surface model is used to study the Bragg scattering from clean sea and contaminated sea in monostatic configurations, and is compared with part of experimental data. The influence of wind speed, and film thickness is analyzed. Emulsified oil and the process of diffusion can form oil-water mixture, at this time, the change of dielectric constant and its influence is introduced. In addition, the influence of waves breaking on the scattering coefficient and polarization ratio is also analyzed.In this paper, not only the composite model is used to calculate the electromagnetic scattering, but also the method of moments(MOM) is used to calculate numerical electromagnetic scattering from the clean sea and contaminated sea. The effect of the oil film on the bistatic scattering coefficient is analyzed. A dimensional sea surface is generated using linear filtering method. The layered media model is used to calculate the bistatic scattering under a variety of parameters, such as, radar frequency and polarization, wind speed, and oil film thickness. The statistical characteristics of the phase that scholars pay less attention to are also studied. The results show that there is a significant difference between the distribution of the co-phase difference of the clean sea and the contaminated sea.