Nicholas P. Chotiros
Frank A. Boyle
Appl. Res. Labs., Univ. of Texas at Austin, P.O. Box 8029, Austin, TX 78713-8029
A new model of acoustic backscatter from the ocean bottom is presented. Based on the analysis of existing data, three main physical mechanisms have been identified. These are gas bubbles, sediment grains, and interface roughness. Gas bubbles are particularly prevalent in shallow water sediments. A single-scatter approximation is used to model the bubble scattering. Scattering from sediment grains is a multiple-scatter problem which is still under investigation, but an empirical relationship is available. Scattering from interface roughness is modeled in terms of a Kirchhoff--Helmholtz scattering integral. The total backscattering strength is an incoherent sum of the three contributions. It is found that the interface roughness is dominant near normal incidence. The other two mechanisms tend to dominant at shallow grazing angles. [Work supported by Naval Research Laboratory, Stennis Space Center under the MCM Tactical Environmental Data System (MTEDS) project.]