Elastic wave scattering in a horizontally stratified ocean environment with application to arctic propagation

Abstract

A previously developed boundary perturbation method [W. A. Kuperman, J. Acoust. Soc. Am. 58, 365 (1975)] is extended to treat scattering at a randomly rough interface which separates viscoclastic media. This method is then combined with a full‐wave treatment of sound propagating in a stratified ocean described by a system of liquid and elastic layers [H. Schmidt and F. B. Jensen, J. Acoust. Soc. Am. 77, 813–825 (1985)]. The net result of combining the extended boundary perturbation method with the full‐wave solution technique is to define a set of effective potentials which, when inserted in the full‐wave solution algorithm, yields the coherent components of the compressional and shear wave fields in the Kirchhoff approximation. The fields decay with range due to boundary roughness scattering into both incoherent compressional and shear waves. A natural outcome of this model is also the option to calculate the coherent reflection coefficient for an arbitrarily arranged layered system of liquid/solid media separated by randomly rough interfaces. Numerical examples of reflection coefficients and sound propagation in an ocean described by a stratified waveguide are presented. Emphasis is on arctic propagation demonstrating a new low‐frequency attenuation mechanism resulting from scattering into shear waves at the upper and lower rough boundaries of an ice layer.