ASA 125th Meeting Ottawa 1993 May

2pUW7. Wave theory modeling of bi-static bottom reverberation in a stratified ocean.

Henrik Schmidt

Dept. of Ocean Eng., MIT, Cambridge, MA 02139

Kevin LePage

BBN Systems and Technol., Cambridge, MA 02138

Huaiyu Fan

MIT, Cambridge, MA 02139

Recent results by Lepage and Schmidt [J. Acoust. Soc. Am. 92, 2467--2468 (A) (1992)] have shown that broadband representations of rough surface scattering scenarios may be obtained for layered acoustic-elastic media by using a computationally efficient, hybrid perturbation/wave-number integration approach. These results are quite general for source characteristics and geometry but up until now the scattered field has only been obtained in the proximity of the scattering patch. Using a formulation similar to the one used by Schmidt and Glattetre for horizontal source arrays in a stratified ocean [J. Acoust. Soc. Am. 78, 2105--2114 (1985)], the two-dimensional Fourier representations of the scattering source strengths can be transformed into a cylindrical representation in terms of a Fourier series of Hankel transforms. The fact that the number of terms in the series is limited by the finite size of the scattering patch, and the fact that the kernels of the Hankel transforms are determined from a single, linear system of equations with multiple right-hand sides, makes this approach extremely efficient for simulation of long range bi-static reverberation. The seismoacoustic bottom reverberation in deep water is investigated for relevant bi-static scenarios, and the importance of elastic properties and the roughness characteristics is investigated. [Work supported by ONR.]