Analysis of acoustic propagation in the region of the New England continental shelfbreak
Sperry, Brian J.
MetadataShow full item record
During July and August of 1996, a large acoustics/physical oceanography experiment was fielded in the Mid-Atlantic Bight, south of Nantucket Island, MA. Known as the Shelfbreak Front PRIMER Experiment, the study combined acoustic data from a moored array of sources and receivers with very high resolution physical oceanographic measurements. This thesis addresses two of the primary goals of the experiment, explaining the properties of acoustic propagation in the region, and tomographic inversion of the acoustic data. In addition, this thesis develops a new method for predicting acoustic coherence in such regions. Receptions from two 400 Hz tomography sources, transmitting from the continental slope onto the shelf, are analyzed. This data, along with forward propagation modeling utilizing SeaSoar thermohaline measurements, reveal that both the shelfbreak front and tidally-generated soliton packets produce stronger coupling between the acoustic waveguide modes than expected. Arrival time wander and signal spread show variability attributable to the presence of a shelf water meander, changes in frontal configuration, and variability in the soliton field. The highly-coupled nature of the acoustic mode propagation prevents detailed tomographic inversion. Instead, methods based on only the wander of the mode arrivals are used to estimate path-averaged temperatures and internal tide "strength". The modal phase structure function is introduced as a useful proxy for acoustic coherence, and is related via an integral transform to the environmental sound speed correlation function. Advantages of the method are its flexibility and division of the problem into independent contributions, such as from the water column and seabed.
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 June 1999
Suggested CitationThesis: Sperry, Brian J., "Analysis of acoustic propagation in the region of the New England continental shelfbreak", 1999-06, DOI:10.1575/1912/4696, https://hdl.handle.net/1912/4696
Showing items related by title, author, creator and subject.
Horizontal coherence of low-frequency fixed-path sound in a continental shelf region with internal-wave activity Duda, Timothy F.; Collis, Jon M.; Lin, Ying-Tsong; Newhall, Arthur E.; Lynch, James F.; DeFerrari, Harry A. (Acoustical Society of America, 2012-02)Sound at 85 to 450 Hz propagating in approximately 80-m depth water from fixed sources to a joint horizontal/vertical line array (HLA/VLA) is analyzed. The data are from a continental shelf area east of Delaware Bay (USA) ...
Preisig, James C.; Duda, Timothy F. (IEEE, 1997-04)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 ...
Mikhalevsky, Peter N.; Sagen, Hanne; Worcester, Peter F.; Baggeroer, Arthur B.; Orcutt, John A.; Moore, Sue E.; Lee, Craig M.; Vigness-Raposa, Kathleen J.; Freitag, Lee E.; Arrott, Matthew; Atakan, Kuvvet; Beszczynska-Möller, Agnieszka; Duda, Timothy F.; Dushaw, Brian D.; Gascard, Jean-Claude; Gavrilov, Alexander N.; Keers, Henk; Morozov, Andrey K.; Munk, Walter H.; Rixen, Michel; Sandven, Stein; Skarsoulis, Emmanuel; Stafford, Kathleen M.; Vernon, Frank L.; Yuen, Mo Yan (Arctic Institute of North America, 2015)The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This activity will be driven by increased demand for energy and the marine resources of an Arctic Ocean accessible ...