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Multiscale multiphysics data-informed modeling for three-dimensional ocean acoustic simulation and prediction

Duda, T.F., Y.-T. Lin, A.E. Newhall, K.R. Helfrich, J.F. Lynch, W.G. Zhang, P.F.J. Lermusiaux, and J. Wilkin, 2019. Multiscale Multiphysics Data-Informed Modeling for Three-Dimensional Ocean Acoustic Simulation and Prediction. Journal of the Acoustical Society of America, sub-judice.

Three-dimensional (3D) underwater sound field computations have been used for a few decades to understand sound propagation effects above a sloped seabed and in areas with strong 3D water mass variations. For an approximate simulation of effects in nature, the necessary 3D sound-speed field can be made from snapshots of temperature and salinity from an operational data- driven regional ocean model. However, these models invariably have resolution constraints and physics approximations that exclude features that can have strong effects on acoustics, example features being strong submesoscale fionts and nonhydrostatic nonlinear internal waves (NNIWs). Here, work to predict NNIW fields to improve 3D acoustic forecasts using an NNIW model nested in a non—NNIW-resolving regional model is reported. The work was initiated under the Integrated Ocean Dynamics and Acoustics proj ect. The project investigated ocean dynamical processes that affect important details of sound-propagation, with a focus on those with strong intermittency (high kurtosis) that are challenging to predict deterministically. Strong internal tides and NNIW are two such phenomena, with the former being precursors to NNIW, often feeding their energy to NNIWs. Successful aspects of the modeling are reported along with weaknesses and unresolved issues identified in the course of the work.