Experimental evidence of three-dimensional acoustic propagation caused by nonlinear internal waves
Frank, Scott D.
Lynch, James F.
Siegmann, William L.
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KeywordAcoustic wave propagation; Acoustic wave refraction; Acoustic intensity; Nonlinear acoustics; Underwater sound
The 1995 SWARM experiment collected high quality environmental and acoustic data. One goal was to investigate nonlinear internal wave effects on acoustic signals. This study continues an investigation of broadband airgun data from the two southwest propagation tracks. One notable feature of the experiment is that a packet of nonlinear internal waves crossed these tracks at two different incidence angles. Observed variations for the lower angle track were modeled using two-dimensional parabolic equation calculations in a previous study. The higher incidence angle is close to critical for total internal reflection, suggesting that acoustic horizontal refraction occurs as nonlinear internal waves traverse this track. Three-dimensional adiabatic mode parabolic equation calculations reproduce principal features of observed acoustic intensity variations. The correspondence between data and simulation results provides strong evidence of the actual occurrence of horizontal refraction due to nonlinear internal waves.
Author Posting. © Acoustical Society of America, 2005. 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 118 (2005): 723-734, doi:10.1121/1.1942428.
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Temporal and cross-range coherence of sound traveling through shallow-water nonlinear internal wave packets Duda, Timothy F. (Acoustical Society of America, 2006-06)Expressions governing coherence scales of sound passing through a moving packet of nonlinear internal waves in a continental shelf environment are presented. The expressions describe the temporal coherence scale at a point, ...
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