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.