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© Woods Hole Oceanographic Institution © University of Washington |
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| Last updated May 2010 |
Acoustic ducting and refraction by sea bottom relief in shallow water
James F. Lynch, Alexey A. Shmelev, Ying-Tsong Lin, and Arthur E. Newhall
| Observations show that shallow water bottom relief often has a band-limited directional spectrum produced by various oceanographic and geological processes. This directional bottom feature is shown to have a noticeable effect on three-dimensional low-frequency acoustic propagation. An analytical study with an idealized model of straight sea bottom ripples has shown that acoustic energy can be partially ducted between neighboring ripples, and this ducting will affect acoustic propagation in shallow water. In our work, we also study ducting and refracting due to idealized curved sea bottom ripples. Previous research has shown that non-linear internal waves can also creat acoustical ducts. Comparative analysis of these two different ducts is performed using our idealized model. The combined effects of internal waves and bathymetry are studied from various relative directions of internal wave front and bottom ripples. A numerical simulation of three-dimensional sound propagation across realistic bathymetry and internal wave fluctuations is performed. In conclusion, both water column fluctuations and bathymetry variability need to be taken into account when studying three-dimensional acoustic propagation in shallow water. |
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© Woods Hole Oceanographic Institution © University of Washington |
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| Last updated May 2010 |