Acoustic coherence in shallow water: theory and observation

This paper is focused on quantitative calculations of the acoustic mutual coherence function (MCF) in random shallow water. Based on the wave-theoretical description the basic equations are formulated for the cross and self-modal coherence functions in shallow water where combined effects of random scattering and bottom interactions are important. The application is illustrated by numerical computation of the expected acoustic coherence for typical shallow-water environments under the assumption that the fully developed seas are the dominant source of transmission fluctuations. The theoretical calculations of the vertical coherence based on wind seas scattering are compared with the observed spatial coherence of the signals received by vertical arrays operating in the Barents Sea. It has been established that the vertical coherence function predicted from the wind seas model is in good qualitative agreement with the presented measurements.