Acoustic Monitoring of Flow Through the Strait of Gibraltar: Data Analysis and Interpretation
CALIFORNIA UNIV REGENTS LA JOLLA CA SCRIPPS INST OF OCEANOGRAPHY
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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. The Strait of Gibraltar is a challenging environment in which to work. Internal undular bores of 100 m amplitude propagate along the interface between an upper layer of Atlantic water and a lower layer of Mediterranean water, eventually evolving into a packet of internal solitary waves. The interface is also strongly modulated by internal tides of comparable amplitude. High-frequency, broadband, underwater acoustic transmissions across the Strait are used to examine acoustic scattering caused by this unique internal wave field and the feasibility of acoustically remote sensing physical processes in the Strait. 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. Our goal is to obtain 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 wish to determine 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.
- Hydrology, Limnology and Potamology
- Acoustic Detection and Detectors