Ocean environmental effects on low‐frequency sound propagation in shallow water with application to marine mammals.

Abstract

In shallow ocean areas (less than 100 m), the water‐column and seafloor structure play a critical role in sound propagation and can influence many different applications of shallow water acoustics including source detection and localization. While the seafloor and subbottom effects on sound propagation are relately well known, water‐column variability, especially that of internal wave activity, thermohaline intrusions, and fronts, are only beginning to be understood, but should be considered when predicting sound propagation in shallow water. For example, termination of the mid water‐column duct by a shelfbreak front or the appearance of an internal wave duct can change acoustic channels which may hinder marine mammal communication or may be exploited by the animals. In this paper, we will examine the effects of the ocean environment on sound propagation in shallow water in the presence of these features in a continental shelf region. Specifically, we will use field data and numerical acoustic simulations to study low‐frequency sound propagation in a dynamic ocean and how it relates to marine mammal vocalization, communication, and localization. [Work supported by ONR.]