ASA 126th Meeting Denver 1993 October 4-8

3aUW4. Acoustic radiation from breaking waves.

Li Ding David M. Farmer

Inst. of Ocean Sci., P.O. Box 6000, Sidney, BC V8L 4B2, Canada

Observations of the sound from breaking surface waves using a small hydrophone array illustrate the temporal and spatial characteristics of this sound source and its dependence on the surface wave field. Such observations provide a source description that might have application in ambient noise model development. By tracking the propagation speed of the breaking event its wave scale is inferred; other measured properties include breaking length, duration, and spatial separation. Analysis indicates that the dependence of breaking probability on the fourth moment of the wave spectrum is consistent with a linear model. The measured speeds of breaking events imply that their scale is less than the dominant wind-wave scale. Group structure of wave breaking, in which there is a tendency for waves to break repetitively at twice the wave period and spaced one wavelength apart, also occurs but is more readily identifiable at lower wind speeds.