The phase perturbation approximation for rough surface scattering from a Pierson-Moskowitz sea surface

The accuracy of the phase perturbation approximation for scattering from a multiscale Pierson-Moskowitz sea surface is examined for large angles of incidence and wind speeds of 10 and 20 m/s. Numerical results for the incoherent bistatic radar cross section and the coherent reflection loss are compared with exact integral equation results. The study is limited to scalar-wave scattering from one-dimensional surfaces with Gaussian surface statistics for the Dirichlet problem. It is found that, for the examples studied, the phase perturbation bistatic radar cross section is accurate away from low scattered grazing angles. In addition, it contains approximations to higher-order classical perturbation cross section terms that partially account for the incoherent intensity structure in the specular region. It is shown that the phase perturbation approximation accurately predicts the coherent reflection loss