ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

1pUW13. A semiempirical model for breaking wave noise fields.

Steven Finette

Richard Heitmeyer

Acoust. Div., Naval Res. Lab., Washington, DC 20375

Mean noise properties, traditionally used for underwater acoustics systems analysis, are not suitable for evaluating the performance of full spectrum processors because they don't have sufficient space/time/frequency resolution. A computer model of the noise field associated with breaking surface waves has been developed in an attempt to address this need. Due to the localized structure of the breaking wave sources, the true ambient noise field is inherently discrete and an attempt has been made to include some properties of the discrete nature of the space-time noise field in the model. The model computes a realization of a time-delay beamformed representation of the acoustic field at a vertical array in a shallow-water environment, given some statistical information about the noise sources. The approach taken is stochastic and semiempirical, incorporating recently obtained experimental data on the acoustic coverage (acoustic analog of whitecap coverage), duration, and source level distributions associated with individual breaking waves (Farmer 1994). Sources are considered to radiate as dipoles, and the radiated fields from the individual discrete sources (breaking waves) are propagated to the array using a wave-number integration technique. [Work supported by ONR.]