ASA 126th Meeting Denver 1993 October 4-8

3aUW8. Model calculation for deviation of ambient noise statistics from signal statistics in shallow water.

Jacob George

Naval Res. Lab., Code 7176, Stennis Space Center, MS 39529

It has been reported that cumulative distribution functions (CDFs) of a signal in shallow water obey normal distributions, while those of ambient noise deviate from this, in both cases independent of depth [J. George, J. Acoust. Soc. Am. 92, 2304 A (1992)]. One cause of intensity fluctuations is internal waves, studied by path integral and moment methods in deep water [B. J. Uscinski et al., J. Acoust. Soc. Am. 74, 1474 (1983)]. In shallow water, internal waves have been shown to behave as solutions [J. Zhou and X. Zhang, J. Acoust. Soc. Am. 90, 2042 (1991)]. For the time spans considered in the CDFs mentioned above (25--320 s) intensity fluctuations caused by surface waves cannot be ignored. Results of a model calculation designed to contrast the effects of a stable signal source below the surface with the effects of ambient noise sources moving with the surface will be presented. [Work supported by ONR.]