Acoustic Monitoring of Flow Through the Strait of Gibraltar: Data Analysis and Interpretation
1998
Worcester, Peter F. | Cornuelle, Bruce D.
Existing techniques do not begin to exploit the full potential of acoustic remote sensing methods to study ocean thermal structure and circulation. This research is intended to improve our understanding of acoustic propagation in shallow-to-intermediate depth environments and to extend tomographic techniques to ocean regimes in which acoustic propagation is more complex than the largely deep water cases studied to date. Understanding the acoustic forward problem in complicated environments is a prerequisite to using tomographic methods. The conditions in the Strait include substantial variability on short time and space scales, including internal bores and trains of interfacial internal waves. The specific issues addressed in this project are: (i) to determine whether one or more acoustic ray paths exist (at 2 kHz) that are resolvable, identifiable, stable, and that provide useful integral measures of the flow; (ii) to measure acoustic scattering due to the internal wave bores in the Strait; and (iii) to study normal mode propagation (at 250 Hz), including the feasibility of using modal analyses, matched field tomography, and full-field inversion techniques to obtain information on the temperature and current fields. At the conclusion of the analyses we expect to have a much better understanding of acoustic propagation in the complex oceanographic environment present in the Strait of Gibraltar and, by extension, in other straits that are two-layer systems. We also expect to have determined which of the various possible acoustic methods for monitoring the transport in the Strait works best, and just how well the various methods tried do work.
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