Aspects of modelling coherent acoustic reflection from a rough seafloor

Acoustic energy incident at a roughened seafloor will result in a component scattered back into the water at non-specular angles, a component reflected coherently at the specular angle, and both coherent and incoherent components being transmitted into, and absorbed within, the seafloor. An initial expectation was that the total coherent reflection loss might be approximated by a combination of the loss attributed to a flat seafloor based on its geoacoustic properties, and the separate coherent loss due to the roughness scattering described for a perfectly reflecting surface. This hypothesis had been verified in limited earlier work, by comparing loss values obtained using this simple addition of model outputs with loss values obtained using the perturbation approach for rough surface scattering from stratified media described by Kuperman and Schmidt (JASA, 86, Oct. 1989). In new work, data obtained using Monte Carlo Parabolic Equation (PE) transmission simulations have been used as an added reference for further verification of the hypothesis