Coupled acoustic mode propagation through continental-shelf internal solitary waves
MetadataShow full item record
Three techniques are used to investigate mode coupling as acoustic energy passes through continental-shelf internal solitary waves (ISW's). Results from all techniques agree. The waves considered here are single downward undulations of a thermocline layer separating upper and lower well-mixed layers. Two techniques are numerical: parabolic equation (PE) solution and a sudden approximation joining range-invariant regions at sharp vertical interfaces. The third technique is an analytic derivation of ISW scale lengths separating adiabatic (at large scale) and coupled-mode propagation. Results show that energy is exchanged between modes as ISW's are traversed. The sharp interface solutions help explain this in terms of spatially confined coupling and modal phase interference. Three regimes are observed: 1) for short ISW's, coupling upon wave entrance is reversed upon exit, with no net coupling; 2) for ISW scales of 75-200 m, modal phase alteration averts the exit reversal, giving net coupling; transparent resonances yielding no net coupling are also observed in this regime; and 3) for long ISW's, adiabaticity is probable but not universal. Mode refraction analysis for nonparallel acoustic-ISW alignment suggests that these two-dimensional techniques remain valid for 0° (parallel) to 65° (oblique) incidence, with an accordant ISW stretching
Author Posting. © IEEE, 1997. This article is posted here by permission of IEEE for personal use, not for redistribution. The definitive version was published in IEEE Journal of Oceanic Engineering 22 (1997): 256-269, doi:10.1109/48.585945.
Suggested CitationArticle: Preisig, James C., Duda, Timothy F., "Coupled acoustic mode propagation through continental-shelf internal solitary waves", IEEE Journal of Oceanic Engineering 22 (1997): 256-269, DOI:10.1109/48.585945, https://hdl.handle.net/1912/4933
Showing items related by title, author, creator and subject.
Enhanced acoustic mode coupling resulting from an internal solitary wave approaching the shelfbreak in the South China Sea Chiu, Linus Y. S.; Reeder, D. Benjamin; Chang, Yuan-Ying; Chen, Chi-Fang; Chiu, Ching-Sang; Lynch, James F. (Acoustical Society of America, 2013-03)Internal waves and bathymetric variation create time- and space-dependent alterations in the ocean acoustic waveguide, and cause subsequent coupling of acoustic energy between propagating normal modes. In this paper, the ...
Preisig, James C.; Deane, Grant B. (Acoustical Society of America, 2004-10)The forward scattering of acoustic signals off of shoaling surface gravity waves in the surf zone results in a time-varying channel impulse response that is characterized by intense, rapidly fluctuating arrivals. In some ...
Stephen, Ralph A.; Bolmer, S. Thompson; Udovydchenkov, Ilya A.; Worcester, Peter F.; Dzieciuch, Matthew A.; Andrew, Rex K.; Mercer, James A.; Colosi, John A.; Howe, Bruce M. (Acoustical Society of America, 2013-10)Ocean bottom seismometer observations at 5000 m depth during the long-range ocean acoustic propagation experiment in the North Pacific in 2004 show robust, coherent, late arrivals that are not readily explained by ocean ...