ASA 125th Meeting Ottawa 1993 May

5aUW4. Bubble clouds as sources of underwater noise.

Hasan N. Oguz

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

Wave breaking and subsequent formation of whitecaps are known to be the major contributor to the wind-dependent ambient noise levels in the ocean in the low-frequency range (100 Hz--1 kHz). A theoretical model that can account for the noise emissions from randomly distributed bubble clouds is developed in this study. The model assumes that individual whitecaps produce bubble plumes that grow as a result of air entrainment at the ocean surface. The injection of bubbles at the base of this plume excites the bubble cloud. With the only experimental input of the whitecap coverage ratio, the underwater ambient noise level is calculated, without the need of empirical constants, by integrating contributions from bubble plumes of all sizes. The results are found to be in good agreement with the available field measurements. [Work supported by the ONR.]