Numerical Study of Low Grazing Range-Resolved Radar Backscatter from the Sea Surface

Statistical properties of X-band sea clutter are studied using 2-dimensional direct numerical simulations. Surfaces are modeled as realizations of a Gaussian random process with the Pierson-Moskowitz or Elfouhaily spectrum. Creamer transform is applied to reproduce the lowest-order non-linearities. Backscattered field at a given frequency is found using the first-principles integral equation technique. Calculations are repeated at a number of frequencies allowing to synthesize surface response to a pulse as short as 2.2 ns. The study is focused on the incidence angle of 85^ circ 5^ circ grazing), with an example at moderate 60^ circ incidence considered as well. Probability density functions (pdfs) for vertically and horizontally polarized clutter are obtained using Monte Carlo trials. The effects of variations in wind speed (sea state) and radar resolution are investigated. The technique also allows isolating and examining the impact of certain electromagnetic and hydrodynamic approximations. Simulated pdfs are compared to Weibull and K distributions.