Research On Calculation And Application Of Electromagnetic Scattering In Rough Sea Surface And Its Complex Environment

Electromagnetic scattering from rough surface has a wide range of applications in remote sensing of environment,radar imaging and geological exploration.The satellite radar altimeter is an important active microwave remote sensor that measures the backscattering coefficient of the sea surface.By measuring the backscattering coefficient of the sea surface,the effective surface wave height(SWH),sea surface height(SSH),and wind speed above the sea surface can be retrieved.However,in the offshore environment or severe sea conditions,the scattering coefficient of the sea surface will be attenuated and the altimeter measurement data will be abnormal.Therefore,the study of the electromagnetic scattering characteristics in China's offshore areas and the attenuation of backscattering coefficients due to foam and rainfall in severe sea conditions is of great significance.Based on the theory and method of rough surface electromagnetic scattering,the scattering coefficients of common background targets in microwave remote sensing are calculated,and the foam and rainfall attenuation are calculated using several models,which would be finally applied in the normal relationship of dual frequency altimeter.The main work of the dissertation is as follows:1.Using Monte Carlo method to simulate one-dimensional and two-dimensional Gaussian spectrum,exponential spectrum,PM spectrum,superposition spectrum of wind wave and swell wave,and the composite random rough surface of sea and ground.2.The complex permittivity of seawater,soil,sea ice,foam,rainfall,and vegetation were calculated,and the influencing factors of their respective dielectric constants were intensively studied.3.The scattering coefficients of several typical rough surfaces of single-layer medium,including sea surface,sea ice,and ground,were calculated by MOM and KA methods.In addition,the scattering coefficients of the rough surface of sea ice-seawater two layers medium was calculated using MOM,and the scattering coefficients of the rough surface of droplets-foam-seawater three layers medium was calculated using the new method of this paper,the calculated results agree well with that of MOM.4.According to the quasi-mirror electromagnetic scattering theory,the attenuation caused by the foam in the C and Ku-band was calculated.Meanwhile,the rainfall attenuation was calculated using the ITU-R model,the multilayer dielectric scattering theory model,the equivalent permittivity model and the approximate model of this paper.5.The theoretical relationship of sea surface backscattering coefficients in Ku and C band is obtained by the numerical calculation methods of MOM and KA,and the four empirical reference relationships are verified and analyzed.