The effect of submarine canyon bathymetry on range estimation using cross-correlated ship noise field

Abstract

Ambient noise data collected on a pair of omni-directional vertically separated hydrophones at the head of Alvin Canyon, a shelf-break submarine canyon, is used to estimate the range and bearing of a passing vessel. Comparison of the vertical coherence data against a Pekeris normal-mode model may be used to provide the range of the ship along bearing lines that do not cross the canyon’s rapidly changing bathymetry. To investigate the effect of bathymetry on the range estimate, a reciprocal three-dimensional Parabolic Equation (3-D PE) model is used to generate a map of the vertical coherence field for all possible ship positions over the domain of a Gaussian canyon, demonstrating that horizontal reflection and refraction lead to focusing of ship noise along the canyon axis. The same method is used to obtain vessel range and bearing information from the data recorded at Alvin Canyon. The vessel bearing relative to the pair of vertically spaced omni-directional receivers is obtained by exploiting the canyon bathymetry.