ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pAO6. A model for underwater ambient noise at low wind speeds.

Hasan N. Oguz

Dept. of Mech. Eng., Johns Hopkins Univ., Baltimore, MD 21218

When the wind speed is low enough, wave breaking does not lead to bubble clouds of substantial size. The collective mode of oscillations that is dominant at high wind speeds may be neglected. In this case, wave breaking that is still the major source of noise is approximated by a finite area of the sea surface over which single bubbles are entrained and emit individual acoustic pulses. Each breaking wave has a certain emission characteristics depending on bubble size distribution, density, wave size, rate of entrainment, etc. An empirical correlation between the whitecap coverage ratio and the wind speed is employed to infer the size of the bubble entrainment area. The contribution of all waves are summed and the ambient noise levels are computed as a function of the wind speed. The results are in good agreement with field measurements. [Work supported by the Office of Naval Research.]