Characterization of acoustic interactions with a scale model of an elastic ocean bottom using deterministic and stochastic representations of the rough surface

The Naval Research Laboratory (NRL) is performing a series of tank experiments to verify the predictions of scattering models for rough surfaces. Rough surfaces milled from blocks of PVC are used as analogs to the rough surface of an elastic ocean bottom (e.g., limestone), and the inputs to scattering models (surface heights, speeds, and attenuations) are measured from material samples. Two surfaces are currently being constructed to have an isotropic, power-law spectrum, but to date, we have used a third surface with only an approximate, variable, power-law spectrum in an acoustic tank experiment. We consider these manufactured rough surfaces both as deterministic entities and realizations from statistical ensembles in performing comparisons of the measured scattering strength as a function of grazing angle with theory. The results show that appropriate application of these theories leads to successful prediction of the detailed behavior of the scattering strength for the quasi-monostatic geometries of the experiments. [Work supported by the Office of Naval Research and the NATO Undersea Research Centre.]