Title

Modeling the Effects of Linear Shallow-Water Internal Waves on Horizontal Array Coherence

Published In

The Journal of the Acoustical Society of America

Document Type

Citation

Publication Date

2015

Abstract

The coherence length of a horizontal array is the maximum separation between two points where coherent processing gives useful gain when a distant source is at broadside. In shallow water, the coherence length is limited by the environmental variability caused by several relevant oceanographic processes. In the present study, a statistical model is developed that quantifies how one oceanographic process, linear internal waves, affects the coherence length. A key input to the ocean sub-model is the vertically integrated energy density of the internal wave field. The acoustic sub-model is based on the adiabatic normal mode approximation and so should be reasonable for frequencies under 1 kHz. Numerical calculations using environmental data from the Shallow Water 2006 Experiment (SW06) show how the coherence length of individual modes varies with consequent effects on array coherence. The coherence length is shown to be a strong function of where the source and array are positioned in the water column. For a bottom-mounted array above a moderately lossy seabed, the model predicts a coherence length that depends only weakly on range, an effect observed in field experiments.

Description

Daniel Rouseff is also affiliated with the University of Washington - Seattle Campus.

DOI

10.1121/1.4930954

Persistent Identifier

http://archives.pdx.edu/ds/psu/19224

Share

COinS