ASA 127th Meeting M.I.T. 1994 June 6-10

3aAO1. Diffraction and chaos for sound propagation through ocean internal waves.

Jeffrey Simmen

Office of Naval Res., Code 3240A, 800 N. Quincy St., Arlington, VA 22217-5660

Guang-yu Wang

Stanley Flatte

Univ. of California, Santa Cruz, CA 95064

The effect of the dynamical ocean on the propagation of sound impulses over long ranges (exceeding several hundred kilometers) is an area of renewed interest, since there is a growing appeal for the use of acoustical tomography as a means of measuring or monitoring the ocean. This presentation will emphasize recent numerical results describing the effects of ocean internal waves on long-range pulse propagation. Elements of the presentation will include the nature of wave front folding as a function of propagation range, the chaotic behavior of rays, as well as its sensitive dependence on average sound-speed profile, and the diffraction due to internal waves. (Comparisons between solutions to the parabolic wave equation and its semiclassical ray counterpart will illustrate the nature of the diffraction.)