ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

5aUW9. Numerical studies of the small slope approximation for rough surface scattering using a Pierson--Moskowitz spectrum.

Shira L. Broschat

School of Elec. Eng. and Comput. Sci., Washington State Univ., Pullman, WA 99164-2752

Eric I. Thorsos

Univ. of Washington, Seattle, WA 98105

The small slope approximation (SSA), introduced by Voronovich in the mid-1980s [A. G. Voronovich, Sov. Phys. JETP 62, 65--70 (1985)], has been shown to be a very promising method for modeling wave scattering from rough surfaces. The theory gives a systematic series which is manifestly reciprocal at each order, reduction to perturbation theory is intrinsic to the formulation, and reduction to the Kirchoff approximation occurs under the appropriate conditions when the first two terms of the series are retained [E. I. Thorsos and S. L. Broschat, 2082--2093 (1995)]. In this paper numerical results are presented for scattering strengths for one-dimensional, pressure release surfaces satisfying a Pierson--Moskowitz power law spectrum. Results are given for incident angles varying from grazing to normal over the full angular range of scattering. Comparisons with Monte Carlo integral equation results show that the SSA is extremely accurate over a large range of scattering angles including low forward grazing angles.