Dynamic coupling of primitive equation soliton models and acoustic propagation models via acoustic mode analysis

Simulation studies of acoustic mode conversions resulting from underwater acoustic fields propagating through solitons in the Strait of Messina have indicated a novel way of coupling oceanographic models with ocean acoustic models using dynamic feedback from the acoustic analysis. A weakly nonhydrostatic primitive equation model was used to generate simulations of oceanographic soliton fields in the Strait of Messina. The soliton fields were used to study acoustic mode conversions as the acoustic field passed through the solitons and propagated upslope. Conversion into modes having higher bottom loss have shown resonance effects similar to that observed in the Yellow Sea. Oceanographic parameters were adjusted so that amplitude and phase of the first two wavelengths of the simulated soliton fields were in agreement with measured soliton data. However, identical acoustic signals propagated through the simulated and measured soliton fields produced different acoustic mode structures. Oceanographic parameter values were varied until the differences in acoustic predictions were minimized. Thus, a feedback approach was used to dynamically couple the oceanographic and acoustic models. Initial results and the suitability of a two-layer oceanographic model for detailed acoustic studies will be discussed. [Work supported by ONR/NRL and by a High Performance Computing DoD grant.]