Departmental Papers (EES)

Document Type

Journal Article

Date of this Version

4-21-2009

Abstract

The hypothesis tested is that internal gravity waves explain temporal and spatial coherences of sound at 1659 km in the Pacific Ocean for a signal at 250 Hz and a pulse resolution of 0.02 s. From data collected with a towed array, the measured probability that coherence time is 1.8 min or longer is 0.8. Using a parabolic approximation for the acoustic wave equation with sound speeds fluctuating from internal waves, a Monte-Carlo model yields coherence time of 1.8 min or more with probability of 0.9. For spatial coherence, two subsections of the array are compared that are separated by 142 and 370 m in directions perpendicular and parallel to the geodesic, respectively. Measured coherence is 0.54. This is statistically consistent with the modeled 95% confidence interval of [0.52, 0.76]. The difference of 370 m parallel to the section causes spatial coherence to degrade deterministically by a larger amount than the effect of internal waves acting on the 142 m separation perpendicular to the section. The models are run without any tuning with data.

Comments

Suggested Citation:
Spiesberger, J.L. (2009). "Temporal and spatial coherence of sound at 250 Hz and 1659 km in the Pacific Ocean: Demonstrating internal waves and deterministic effects explain observations." J. Acoust. Soc. Am. 126 (1).

© 2009 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America. The following article appeared in J. Acoust. Soc. Am. and may be found at http://dx.doi.org/10.1121/1.3133243

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Date Posted: 22 December 2010

This document has been peer reviewed.