Multispectra for ocean-like random rough surface scattering

Abstract

An approximate expression of the scattering coefficient, for electromagnetic waves scattering from a random rough surface, is used in order to show in a simple way how multicovariance functions, and their Fourier transforms or multispectra, are naturally introduced. In fact, particular combinations of the moments are required that depend only on the separation distance between two points of the surface. The functions of lowest order are the correlation function, the skewness function and the peakedness function. Some properties of these functions are discussed. The particular case of a normal surface is briefly considered. Examples of skewness and peakedness functions, depending on characteristic distances, are discussed, and relationships are established between these distances and the wind speed for the ocean surface.