Statistics of low-frequency normal-mode amplitudes in an ocean with random sound-speed perturbations : shallow-water environments


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dc.contributor.author Colosi, John A.
dc.contributor.author Duda, Timothy F.
dc.contributor.author Morozov, Andrey K.
dc.date.accessioned 2012-03-21T15:32:04Z
dc.date.available 2012-03-21T15:32:04Z
dc.date.issued 2012-02
dc.identifier.citation Journal of the Acoustical Society of America 131 (2012): 1749-1761 en_US
dc.identifier.uri http://hdl.handle.net/1912/5091
dc.description Author Posting. © Acoustical Society 2012. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 131 (2012): 1749-1761, doi:10.1121/1.3666002. en_US
dc.description.abstract Second- and fourth-moment mode-amplitude statistics for low-frequency ocean sound propagation through random sound-speed perturbations in a shallow-water environment are investigated using Monte Carlo simulations and a transport theory for the cross-mode coherence matrix. The acoustic observables of mean and mean square intensity are presented and the importance of adiabatic effects and cross-mode coherence decay are emphasized. Using frequencies of 200 and 400 Hz, transport theory is compared with Monte Carlo simulations in a canonical shallow-water environment representative of the summer Mid-Atlantic Bight. Except for ranges less than a horizontal coherence length of the sound structure, the intensity moments from the two calculations are in good agreement. Corrections for the short range behavior are presented. For these frequencies the computed mode coupling rates are extremely small, and the propagation is strongly adiabatic with a rapid decay of cross-mode coherence. Coupling effects are predicted to be important at kilohertz frequencies. Decay of cross-mode coherence has important implications for acoustic interactions with nonlinear internal waves: For the case in which the acoustic path is not at glancing incidence with a nonlinear internal-wave front, adiabatic phase randomizing effects lead to a significantly reduced influence of the nonlinear waves on both mean and mean square intensity. en_US
dc.description.sponsorship This work was supported by the Office of Naval Research and the Naval Undersea Warfare Center’s Under- Sea Warfare chair at the Naval Postgraduate School. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher Acoustical Society of America en_US
dc.relation.uri http://dx.doi.org/10.1121/1.3666002
dc.subject Monte Carlo methods en_US
dc.subject Perturbation techniques en_US
dc.subject Seawater en_US
dc.subject Short-range order en_US
dc.subject Statistics en_US
dc.subject Underwater acoustic propagation en_US
dc.title Statistics of low-frequency normal-mode amplitudes in an ocean with random sound-speed perturbations : shallow-water environments en_US
dc.type Article en_US
dc.identifier.doi 10.1121/1.3666002

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