General analysis of ocean eddy effects for sound transmission applications

Abstract

An analytical approach is used to obtain an approximate solution for deep-ocean mesoscale eddies, including depth-dependent effects. The solution is used in the development of an environmental-acoustics model which relates acoustically relevant quantities, such as sound-speed and current distributions, to eddy parameters. Parameters of the model are depth of influence, radius, rotational direction and maximum speed, and translational velocity. An application to a particular Gulf Stream ring is made, and the resulting current and soundspeed structures are shown to be in good agreement with observations. Then, general results are presented for rotational current structure, maximum horizontal sound-speed change, and maximum SOFAR-axis elevation as functions of eddy radius and peak current speed. It is shown explicitly how these quantities change significantly with eddy size and strength. This model provides a basis for subsequent analytical studies of sound transmission through an arbitrary eddy or eddy field. [Work supported by ONR.]