Scattering from layered seafloors: Comparisons between theory and integral equations

TL;DR

This paper compares various theoretical models for acoustic scattering from layered seafloors with rough interfaces, introducing an integral equation approach and evaluating the accuracy of existing approximations.

Contribution

It presents an integral equation model for layered seafloor scattering and compares it with existing approximations to determine their relative accuracy.

Findings

Jackson and Olson's small slope approximation is most accurate for large roughness.

Models agree closely when roughness is small.

The integral equation approach provides a benchmark for model validation.

Abstract

Acoustic scattering from layered seafloors exhibits dependence on both the mean geoacoustic layering, as well as the roughness properties of each layer. Several theoretical treatments of this environment exist, including the small roughness perturbation approximation, the Kirchhoff approximation, and three different versions of the small slope approximation. All of these models give different results for the scattering cross section and coherent reflection coefficient, and there is currently no way to distinguish which model is the most correct. In this work, an integral equation for scattering from a layered seafloor with rough interfaces is presented, and compared with small roughness perturbation method, and two of the small slope approximations. It is found that the most recent small slope approximation by Jackson and Olson is the most accurate when the root mean square (rms) roughness is large, and some models are in close agreement with each other when the rms roughness is small.