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| Content Provider | IEEE Xplore Digital Library |
|---|---|
| Author | Farmer, D.M. Deane, G.B. Vagle, S. |
| Copyright Year | 1976 |
| Abstract | High-frequency propagation close to an active surf line is explored with 12and 100-kHz propagation paths together with measurements of bubble clouds, bubble size distributions, and waves. Breaking waves inject massive bubble plumes that are mixed downwards from the roller region by intense turbulence. If these injections follow one another at intervals less than the time taken for the bubbles to rise to the surface, acoustic signals will be continuously blocked, forming an acoustical barrier that effectively inhibits any propagation. Occasionally, waves break seaward of this barrier. In this case, dense bubble clouds are mixed down beneath the air entrainment zone, but there is sufficient time for them to disappear before succeeding breakers, allowing intermittent high-frequency propagation recharge the bubble field. The duration and shape of signal dropouts are then determined by the selective removal of bubbles by buoyancy and dissolution. In addition to turbulence created by the air entrainment process, a lower level of continuous background turbulence may be generated by interaction of residual currents with the wave boundary layer. Our observations illustrate the variable character of acoustic blocking by bubble clouds and serve as a basis for quantitative analysis of these effects with a 2D propagation model coupled to 2D models of bubble cloud evolution and background turbulence. |
| Sponsorship | IEEE Oceanic Engineering Society |
| Starting Page | 113 |
| Ending Page | 124 |
| Page Count | 12 |
| File Size | 618530 |
| File Format | |
| ISSN | 03649059 |
| Volume Number | 26 |
| Issue Number | 1 |
| Language | English |
| Publisher | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Publisher Date | 2001-01-01 |
| Publisher Place | U.S.A. |
| Access Restriction | One Nation One Subscription (ONOS) |
| Rights Holder | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Subject Keyword | Clouds Acoustic propagation Acoustic measurements Sea measurements Surface acoustic waves Sea surface Oceans Surface morphology Surface topography Shape |
| Content Type | Text |
| Resource Type | Article |
| Subject | Ocean Engineering Mechanical Engineering Electrical and Electronic Engineering |
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