Sound speed profile inversion by matching acoustic intensity striations in shallow water

Abstract

Estimating the sound speed profile by matching modeled acoustic intensity striations to those that are measured with a mounted horizontal line array is investigated. Due to constructive and destructive interference between normal modes, the acoustic intensity manifests a range-frequency striation structure in shallow water, which can be described by the waveguide invariant. Using environmental measurements from the SW'06 experiment; the effects of sound speed profile (SSP) fluctuation on the acoustic intensity interference pattern are simulated. The simulation shows that the changes in the waveguide invariant are determined by isotherm thickness. The acoustic data recorded in an experiment conducted in the South China Sea in June 2010 are analyzed to invert for the sound speed profiles. The sound speed profile is represented by Empirical Orthogonal Functions (EOFs) to reduce the unknown parameters. The estimates agree well with the measured sound speed profiles. Most of the standard deviations are less than 1 m/s.