A direct inversion scheme to obtain sediment sound speed and density in shallow water

Abstract

A simple inversion scheme is described for estimating the sound speed and density in the seabed for Pekeris-type waveguides. At a fixed frequency, input data to the inversion algorithm are discrete values of the phase of the plane wave reflection coefficient at the water/bottom interface. Above the critical angle, the input data are derived from estimates of the horizontal wave numbers for propagating modes in the wave guide. For two or more propagating modes, a linear system of equations is solved directly to determine sound speed and density in the bottom. The approach is strictly only valid for determining properties of the lower half-space in a Pekeris Wave guide. However, in certain circumstances, the approach can be applied to determine properties of the topmost sediment in layered media. The method is demonstrated on a synthetic data set and then applied to data collected at sea. [Work supported by an ONR Ocean Acoustics Entry-Level Faculty Award.]