2pUW13. Acoustic scintillations in the Straits of Florida.

Session: Tuesday Afternoon, December 3

Time: 4:44

Abstract:

Using the UMPE acoustic model, Monte Carlo numerical studies of sound propagation in a realistic shallow-water environment that simulates the Straits of Florida, including internal wave fluctuations and bottom roughness, have been performed. Results show that the sound intensity at distant receivers scintillates dramatically. The acoustic scintillation index, SI=/[sup 2]-1, increases exponentially with propagation range and is significantly greater than unity at ranges beyond about 10 km. This result supports the recent theoretical prediction of Creamer [J. Acoust. Soc. Am. 99, 2825--2836 (1996)]. Statistical analyses show that the distribution of intensity of the random wave fields saturates to the expected Rayleigh distribution with SI=1 at short range (about 5 km) due to multipath effects, and then SI increases exponentially and the intensity distribution approaches a log-normal distribution to an excellent approximation. This ``supersaturation'' effect is found to be universal at long ranges in waveguides having lossy boundaries, and is believed to have fundamental implications for statistical physics. [Work supported by ONR.]