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Scattering of Sound by Internal Wave Currents: The Relation to Vertical Momentum Flux

Munk, W. and Worcester, P. and Zachariasen, F. (1981) Scattering of Sound by Internal Wave Currents: The Relation to Vertical Momentum Flux. Journal of Physical Oceanography, 11 (4). pp. 442-454. ISSN 0022-3670.

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Internal waves scatter sound by two related perturbations: 1) those associated with vertical particle displacements ζ(x, y, z, t) in the presence of a vertical gradient of (potential) sound speed δc = ζ∂(_z)c(_p)); and 2) those associated with horizontal particle velocities u(x, y, z, t). The combined fractional perturbation in propagation velocity is δc/c + u/c. The second term, generally neglected, introduces a nonreciprocity when source and receiver are interchanged. Nonreciprocity is expected to be relatively small except for transmission along a deep downward loop. The principal internal wave contribution to nonreciprocity is from inertial frequencies. The sum and difference of reciprocal travel times are a measure of ζ and u, respectively, along the ray path; the quadrature spectrum of reciprocal travel times is related by an integral equation to the spectrum of the momentum flux 〉ζu〈. Precise measurements of nonreciprocity could provide an estimate of the vertical momentum flux in an internal wave field.

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Additional Information:© 1981 American Meteorological Society. Received September 19, 1980; Accepted January 8, 1981. Some of this material was contained in JASON Summer Report 1977-21. We are indebted to the Office of Naval Research for supporting this investigation.
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Office of Naval Research (ONR)UNSPECIFIED
Record Number:CaltechAUTHORS:20120718-154251708
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Official Citation:Munk, W., P. Worcester, F. Zachariasen, 1981: Scattering of sound by internal wave currents: the relation to vertical momentum flux. J. Phys. Oceanogr., 11, 442–454. doi:<0442:SOSBIW>2.0.CO;2
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:32569
Deposited By: Aucoeur Ngo
Deposited On:18 Jul 2012 23:14
Last Modified:26 Dec 2012 15:37

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