An investigation on sea surface wave spectra and approximate scattering theories

In this paper, we present a survey of some of the most common analytical approximate models that are used to describe the microwave sea surface scattering. The main strengths and weaknesses of the various methods are identified and critically discussed. Such models combine an adequate sea surface description with advanced electromagnetic theories to simulate both monostatic and bistatic scattering for a wide range of wind speeds, radar frequencies, incidence angles, different polarizations and arbitrary radar look direction with respect to the wind direction. Theoretical calculations for co-polar signals in C-band and Ku-band are in good overall agreement with the experimental data represented by the empirical models, CMOD5 and NSCAT, with the exception of HH-polarization at high incidence angles (above 40°). A parametric analysis on the sea surface spectrum, will demonstrate that the discrepancy between the measured and the simulated HH normalized radar cross-sections, is only in part due to the inefficiency of the spectrum and mostly due to additional scattering contribution from breaking waves, not taken into account by the most common analytical scattering theories.