Publication:
Observations of sound-speed fluctuations in the western Philippine Sea in the spring of 2009

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Authors
Colosi, John A.
Van Uffelen, Lora J.
Cornuelle, Bruce D.
Dzieciuch, Matthew A.
Worcester, Peter F.
Dushaw, Brian D.
Ramp, Steven R.
Subjects
Advisors
Date of Issue
2013-10
Date
October 2013
Publisher
Language
Abstract
As an aid to understanding long-range acoustic propagation in the Philippine Sea, statistical and phenomenological descriptions of sound-speed variations were developed. Two moorings of oceanographic sensors located in the western Philippine Sea in the spring of 2009 were used to track constant potential-density surfaces (isopycnals) and constant potential-temperature surfaces (isotherms) in the depth range 120–2000 m. The vertical displacements of these surfaces are used to estimate sound-speed fluctuations from internal waves, while temperature/salinity variability along isopycnals are used to estimate sound-speed fluctuations from intrusive structure often termed spice. Frequency spectra and vertical covariance functions are used to describe the space-time scales of the displacements and spiciness. Internal-wave contributions from diurnal and semi-diurnal internal tides and the diffuse internal-wave field [related to the Garrett–Munk (GM) spectrum] are found to dominate the sound-speed variability. Spice fluctuations are weak in comparison. The internal wave and spice frequency spectra have similar form in the upper ocean but are markedly different below 170-m depth. Diffuse internal-wave mode spectra show a form similar to the GM model, while internal-tide mode spectra scale as mode number to the minus two power. Spice decorrelates rapidly with depth, with a typical correlation scale of tens of meters.
Type
Article
Description
The article of record as published may be found at http://dx.doi.org/10.1121/1.4818784
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Office of Naval Research
Funder
Format
16 p.
Citation
J. Acoust. Soc. Am. 134 (4), Pt. 2, (October 2013), p. 3185-3200
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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