Observationally constrained modeling of sound in curved ocean internal waves: Examination of deep ducting and surface ducting at short range
MetadataShow full item record
KeywordAcoustic field; Acoustic focusing; Acoustic intensity; Acoustic wave scattering; Acoustic wave velocity; Ocean waves; Oceanographic regions; Underwater acoustic propagation
A study of 400 Hz sound focusing and ducting effects in a packet of curved nonlinear internal waves in shallow water is presented. Sound propagation roughly along the crests of the waves is simulated with a three-dimensional parabolic equation computational code, and the results are compared to measured propagation along fixed 3 and 6 km source/receiver paths. The measurements were made on the shelf of the South China Sea northeast of Tung-Sha Island. Construction of the time-varying three-dimensional sound-speed fields used in the modeling simulations was guided by environmental data collected concurrently with the acoustic data. Computed three-dimensional propagation results compare well with field observations. The simulations allow identification of time-dependent sound forward scattering and ducting processes within the curved internal gravity waves. Strong acoustic intensity enhancement was observed during passage of high-amplitude nonlinear waves over the source/receiver paths, and is replicated in the model. The waves were typical of the region (35 m vertical displacement). Two types of ducting are found in the model, which occur asynchronously. One type is three-dimensional modal trapping in deep ducts within the wave crests (shallow thermocline zones). The second type is surface ducting within the wave troughs (deep thermocline zones).
Author Posting. © Acoustical Society of America, 2011. 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 130 (2011): 1173-1187, doi:10.1121/1.3605565.
Showing items related by title, author, creator and subject.
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 ...
Low-frequency broadband sound source localization using an adaptive normal mode back-propagation approach in a shallow-water ocean Lin, Ying-Tsong; Newhall, Arthur E.; Lynch, James F. (Acoustical Society of America, 2012-02)A variety of localization methods with normal mode theory have been established for localizing low frequency (below a few hundred Hz), broadband signals in a shallow water environment. Gauss-Markov inverse theory is employed ...
Udovydchenkov, Ilya A.; Stephen, Ralph A.; Duda, Timothy F.; Bolmer, S. Thompson; Worcester, Peter F.; Dzieciuch, Matthew A.; Mercer, James A.; Andrew, Rex K.; Howe, Bruce M. (Acoustical Society of America, 2012-10)Data collected during the 2004 Long-range Ocean Acoustic Propagation Experiment provide absolute intensities and travel times of acoustic pulses at ranges varying from 50 to 3200 km. In this paper a subset of these data ...