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.]