Abstract:
Low grazing angle acoustic scattering by an irregular ocean floor is considered. The ocean bottom is modeled as a semi-infinite acoustic medium with properties that differ from those of the fluid above. At zero grazing incidence, a flat ocean floor appears acoustically soft. Surface roughness introduces perturbations to both the surface height and the apparent impedance of the interface. This nonuniform limit is examined as a perturbation from a slightly rough pressure release surface. A modified parabolic equation is derived which describes the acoustic amplitude to large distances, and takes into account multiple scattering and radiation into the ocean and bottom. An equivalent formulation will be presented in terms of an integral equation which is solved numerically. Average results as well as results from single realizations are presented. [Work supported by NATO.]