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  • 1
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    Three-dimensional acoustic propagation through shallow water internal, surface gravity and bottom sediment waves (2011)
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2011
    Description: This thesis describes the physics of fully three-dimensional low frequency acoustic interaction with internal waves, bottom sediment waves and surface swell waves that are often observed in shallow waters and on continental slopes. A simple idealized model of the ocean waveguide is used to analytically study the properties of acoustic normal modes and their perturbations due to waves of each type. The combined approach of a semi-quantitative study based on the geometrical acoustics approximation and on fully three-dimensional coupled mode numerical modeling is used to examine the azimuthal dependence of sound wave horizontal reflection from, transmission through and ducting between straight parallel waves of each type. The impact of the natural crossings of nonlinear internal waves on horizontally ducted sound energy is studied theoretically and modeled numerically using a three-dimensional parabolic equation acoustic propagation code. A realistic sea surface elevation is synthesized from the directional spectrum of long swells and used for three-dimensional numerical modeling of acoustic propagation. As a result, considerable normal mode amplitude scintillations were observed and shown to be strongly dependent on horizontal azimuth, range and mode number. Full field numerical modeling of low frequency sound propagation through large sand waves located on a sloped bottom was performed using the high resolution bathymetry of the mouth of San Francisco Bay. Very strong acoustic ducting is shown to steer acoustic energy beams along the sand wave’s curved crests.
    Description: Office of Naval Research for the financial support of this work.
    Keywords: Acoustic models ; Internal waves
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 2
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    Acoustic and oceanographic observations and configuration information for the WHOI moorings from the SW06 experiment (2007)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: This document describes data, sensors, and other useful information pertaining to the moorings that were deployed from the R/V Knorr from July 24th to August 4th, 2006 in support of the SW06 experiment. The SW06 experiment was a large, multi-disciplinary effort performed 100 miles east of the New Jersey coast. A total of 62 acoustic and oceanographic moorings were deployed and recovered. The moorings were deployed in a “T” geometry to create an along-shelf path along the 80 meter isobath and an across-shelf path starting at 600 meters depth and going shoreward to a depth of 60 meters. A cluster of moorings was placed at the intersection of the two paths to create a dense sensor-populated area to measure a 3-dimensional physical oceanography. Environmental moorings were deployed along both along-shelf and across-shelf paths to measure the physical oceanography along those paths. Moorings with acoustic sources were placed at the outer ends of the “T” to propagate various signals along these paths. Five single hydrophone receivers were positioned on the across shelf path and a vertical and horizontal hydrophone array was positioned at the intersection of the “T” to get receptions from all the acoustics assets that were used during SW06.
    Description: Funding was provided by the Office of Naval Research under Contract No. N00014-04-10146
    Keywords: Underwater acoustics ; Oceanographic buoys ; Knorr (Ship : 1970-) Cruise KN183 ; Knorr (Ship : 1970-) Cruise KN184 ; Knorr (Ship : 1970-) Cruise KN185 ; Knorr (Ship : 1970-) Cruise KN186 ; Oceanus (Ship : 1975-) Cruise OC427 ; Oceanus (Ship : 1975-) Cruise OC428 ; Oceanus (Ship : 1975-) Cruise OC429 ; Endeavor (Ship: 1976-) Cruise EN424 ; Endeavor (Ship: 1976-) Cruise EN425 ; Hugh R. Sharp (Ship) Cruise 060622CM
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 3
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    Three-dimensional coupled mode analysis of internal-wave acoustic ducts (2014)
    Acoustical Society of America
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © Acoustical Society of America, 2014. 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 135 (2014): 2497-2512, doi:10.1121/1.4869847.
    Description: A fully three-dimensional coupled mode approach is used in this paper to describe the physics of low frequency acoustic signals propagating through a train of internal waves at an arbitrary azimuth. A three layer model of the shallow water waveguide is employed for studying the properties of normal modes and their coupled interaction due to the presence of nonlinear internal waves. Using a robust wave number integration technique for Fourier transform computation and a direct global matrix approach, an accurate three-dimensional coupled mode full field solution is obtained for the tonal signal propagation through straight and parallel internal waves. This approach provides accurate results for arbitrary azimuth and includes the effects of backscattering. This enables one to provide an azimuthal analysis of acoustic propagation and separate the effects of mode coupled transparent resonance, horizontal reflection and refraction, the horizontal Lloyd's mirror, horizontal ducting and anti-ducting, and horizontal tunneling and secondary ducting.
    Description: This work was supported by the Office of Naval Research under grant Nos. N00014-11-1-0195 and N00014-11-1-0701. Dr. Shmelev gratefully acknowledges the MIT/WHOI Joint Program in Oceanography for additional support.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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