Acoustic wave reflection from a rough seabed with a continuously varying sediment layer overlying an elastic basement

Abstract

Acoustic plane wave interactions with a rough seabed with a continuously varying density and sound speed in a fluid-like sediment layer overlying an elastic basement is considered in this paper. The sediment layer possesses a generalized exponential type of variation in density and one of the three classes of sound speed profiles, which are constant, k 2-linear, or inverse-square variations. Analytical solutions for the Helmholtz equation in the sediment layer, combined with a formulation based upon boundary perturbation theory, facilitate numerical implementation for the solution of coherent field. The coherent reflection coefficients corresponding to the aforementioned density and sound speed profiles for various frequencies, roughness parameters, basement stiffness, are numerically generated and analyzed. Physical interpretations are provided for various results. The proposed model characterizes three important features of a realistic sea floor, including seabed roughness, sediment inhomogeneities, and basement shear property, therefore, provides a canonical environmental model for the study of seabed acoustics.