Use of a Vertical Receiving Array for Geoacoustic Inversion in a Shallow-Water Waveguide with an Ice Cover

Abstract

A method for solving an inverse problem, which consists in the simultaneous assessment of the bottom topography and lake bed effective acoustic parameters for a shallow-water area covered with ice, is developed. This area is a plane waveguide of variable cross section. The method is based on the reception and processing of broadband (pulse) signals excited by a single sound source and recorded by a remote vertical chain of hydrophones (array). The bottom topography measurements are carried out by comparing the propagation times of signals reflected from the lower boundary of the waveguide and arriving at different array hydrophones. The effective parameters (sound speed, density, attenuation coefficient of acoustic waves) are determined by analyzing the angular dependence of the reflection coefficient, calculated as the ratio of the amplitude of the pulse reflected from the bottom to the amplitude of the direct signal, taking into account the spherical spreading of the wave front. Experiments to test the proposed approach were carried out in the coastal zone of Lake Baikal in the winter–spring period.