Abstract:

Numerical results for the incoherent bistatic scattering strength for the nonlocal small-slope approximation (NLSSA) for scattering from rough surfaces [A. G. Voronovich, Waves Random Media 6, 151--167 (1996)], using a Gaussian spectrum, were recently reported [S. L. Broschat and E. I. Thorsos, J. Acoust. Soc. Am. 100, 2702 (1996)]. The cases considered agreed well with exact integral equation results and demonstrated the potential of the NLSSA for accurate modeling of rough surface scattering. In this paper, results for the coherent reflection loss for one-dimensional surfaces are presented. Coherent loss is of particular importance in long-range acoustic propagation when the cumulative effect of multiple interactions with the surface can be significant. The lowest-order NLSSA reflection coefficient is derived, and numerical results are shown for the reflection loss at low grazing angles, using a Pierson--Moskowitz sea surface spectrum. The numerical results are compared with those of other approximate methods and agree well with exact integral equation results. [Work supported by ONR.]