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The “Integrated Ocean Dynamics and Acoustics” (IODA) Hybrid Modeling Effort

Duda, T.F., Y.-T. Lin, A.E. Newhall, K.R. Helfrich, W.G. Zhang, M. Badiey, P.F.J. Lermusiaux, J.A. Colosi, and J.F. Lynch, 2014. The “Integrated Ocean Dynamics and Acoustics” (IODA) Hybrid Modeling Effort, Proceedings of the international conference on Underwater Acoustics - 2014 (UA2014), 621-628.

Regional ocean models have long been integrated with acoustic propagation and scattering models, including work in the 1990s by Robinson and Lee. However, the dynamics in these models has been not inclusive enough to represent submesoscale features that are now known to be very important acoustically. The features include internal waves, thermohaline intrusions, and details of fronts. In practice, regional models predict internal tides at many locations, but the nonlinear steepening of these waves and their conversion to short nonlinear waves is often improperly modeled, because computationally prohibitive nonhydrostatic pressure is needed. To include the small-scale internal waves of tidal origin, a nested hybrid model is under development. The approach is to extract long-wavelength internal tide wave information from tidally forced regional models, use ray methods or mapping methods to determine internal-tide propagation patterns, and then solve two-dimensional high-resolution nonhydrostatic wave models to “fill-in” the internal wave details. The resulting predicted three-dimensional environment is then input to a fully three-dimensional parabolic equation acoustic code. The output from the nested ocean model, run in hindcast mode, is to be compared to field data from the Shallow Water 2006 (SW06) experiment to test and ground truth purposes