ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

1pAO6. Modeling backscatter from a shallow-water soliton: Relationship to the anomalous resonance effect observed in Yellow Sea data.

Stanley A. Chin-Bing

David B. King

Naval Res. Lab., Stennis Space Center, MS 39529-5004

Computer simulations have confirmed that large amplitude shallow-water internal waves (solitons) can effect transmission loss. Zhou et al. [J. Acoust. Soc. Am. 82, 287--292 (1987)] first hypothesized that solitons caused the anomalous transmission loss observed in acoustic data taken in the Yellow Sea. Others [Chin-Bing et al., Math. Model. Sci. Comput. 4, (1994); King et al., Theoret. Comput. Acoust. 2, 793--807 (1994)] confirmed via computer simulations that interactions of acoustic energy with shallow-water solitons resulted in coupling between the lower-order propagation modes and the very lossy, higher-order modes. Furthermore, a single soliton packet could transfer sufficient acoustic energy from lower-order modes to higher-order bottom-attenuated modes to produce the anomalous transmission loss effects observed in the Zhou data. Recently this simulation study has been extended to include a wave-number analysis of the backscattered field from the soliton. Examples of the backscattered field from the soliton will be presented that include the frequency interval where the forward-field acoustic mode conversion (and corresponding anomalous transmission loss) occur. [Work supported by ONR/NRL and by a Federal High Performance Computing DoD grant.]