Analysis of internal wave induced mode coupling effects on the 1995 SWARM experiment acoustic transmissions
Citable URI
https://hdl.handle.net/1912/5730Location
New Jersey coastDOI
10.1575/1912/5730Keyword
Solitons; Underwater acoustics; Internal wavesAbstract
As part of the Shallow Water Acoustics in a Random Medium (SWARM) experiment
[1], a sixteen element WHOI vertical line array (WVLA) was moored in 70 meters
of water off the New Jersey coast. This array was sampled at 1395 Hz or higher for
the seven days it was deployed. Tomography sources with carrier frequencies of 224
and 400 Hz were moored about 32 km shoreward, such that the acoustic path was
anti-parallel to the primary propagation direction for shelf generated internal wave
solitons. Two models for the propagation of normal modes through a 2-D waveguide
with solitary internal wave (soliton) scattering included are developed to help
in understanding the very complicated mode arrivals seen at the WVLA. The simplest
model uses the Preisig and Duda [2] sharp interface approximation for solitons,
allowing for rapid analysis of the effects of various numbers of solitons on mode arrival
statistics. The second model, using SWARM thermistor string data to simulate
the actual SWARM waveguides, is more realistic, but much slower. The analysis of
the actual WVLA data yields spread, bias, wander, and intensity fluctuation signals
that are modulated at tidal frequencies. The signals are consistent with predicted
relationships to the internal wave distributions in the waveguides.
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 June 1997
Suggested Citation
Thesis: Headrick, Robert H., "Analysis of internal wave induced mode coupling effects on the 1995 SWARM experiment acoustic transmissions", 1997-06, DOI:10.1575/1912/5730, https://hdl.handle.net/1912/5730Related items
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