Study on Sea Surface Spectrum Model for Electromagnetic Scattering in Ku-Band Based on Two-Scale Model

The wave spectrum model of ocean surface, which describes the statistical characteristics of ocean surface fluctuation, is very important to electromagnetic scattering modeling of ocean surface. By dividing the wave spectrum into large-scale and small-scale parts, the two-scale model (TSM) combines Kirchhoff approximation (KA) with the small perturbation method (SPM) to expand the application range of the model. This paper uses the TSM to study the simulation performance of Durden-Vesecky (DV) spectrum, Apel spectrum and Elfouhaily spectrum in Ku-band. The cutoff wavenumber is one of the most important factors affecting the accuracy of TSM simulation. We simulate the backscattering coefficients by TSM with different cutoff wavenumbers, and compare with the NSCAT-4 geophysical model function (GMF) to find the minimum absolute error. Then these minimum absolute errors are used to calculate the mean absolute error to select the most appropriate wave spectrum model. The simulation results of different spectrums demonstrate that the Apel spectrum is more suitable for backscattering simulation of rough sea surfaces in Ku-band when the incidence angle is 30° ~ 66° and the wind speed is 3 ~ 20 m/s.