Integrated Modeling and Analysis of Physical Oceanographic and Acoustic Processes [report]

Timothy F. Duda, James F. Lynch, Ying-Tsong Lin, Karl R. Helfrich, Weifeng G. Zhang, Harry L. Swinney, John Wilkin, Pierre F. Lermusiaux, Nicholas C. Makris, Dick K. Yue
2013 unpublished
The long-term goal is to improve ocean physical state and acoustic state predictive capabilities. The goal fitting the scope of this project is the creation of physics-based, broadly applicable and portable acoustic prediction capabilities that include the effects of internal waves, surface waves, and larger scale features, with an emphasis on continental shelf and slope regions. OBJECTIVES A fundamental objective is to improve knowledge of oceanographic processes that are known to be relevant
more » ... o underwater acoustic conditions, yet are not completely understood, to shed light on predictability. Project-scale objectives are to complete targeted studies of oceanographic processes in a few regimes, accompanied by studies of acoustic propagation and scattering processes in those regimes. Internal gravity waves and other submesoscale features are of specific interest. There are many open questions regarding the processes of internal-wave formation and propagation in the presence of lowfrequency large-scale ocean features, to be pursued by the basic research efforts of this project. An additional objective is to develop improved computational tools for acoustics and for the physical processes identified by the targeted studies to be important, including work on data-driven ocean flow models. Time-stepped three-dimensional (3.5D) and true four-dimensional (4D) computational acoustic models are to be improved, as well as the methods used to couple them with ocean flow models. Fully numerical ocean flow modeling will also be improved by coupling models having nonhydrostatic pressure (NHP) physics, data-driven regional models having hydrostatic pressure (HP) physics, and surface wave models. Stochastic acoustic prediction models will be developed. The entire suite of models is to be tested for acoustic prediction effectiveness using existing data sets. APPROACH The approach toward advancing the state of the art is to first identify acoustically relevant ocean processes, to improve environmental models of these processes, and then to use these models to study and predict the acoustic effects in detail, for comparison with existing data. The acoustical relevance of each process is best obtained with state-of-the-art acoustics research using the latest tools, with some tools in need of refinement or development, which forms part of this project. The acoustical relevancy of the processes may be such that relevancy ranking may differ from that obtained from the process relevancy rankings for ocean ecosystem, climate, or ocean biogeochemical cycle research. For example, the size, shape, direction and precise location of nonlinear internal waves is relevant because of localized acoustic effects that scale with wave size, but this level of detail is not often needed for studies of nonlinear wave impact on local ecosystems or water mass mixing. The research plan anticipates feedback, i.e. as the research evolves, goals and priorities may change. This approach has been broken into seven tasks directed toward two goals, equivalent to the objectives listed above: (Goal #1) Development of integrated tools for joint oceanography/acoustic study and prediction, i.e. a modeling system; and (Goal #2) Develop an understanding of the physics of coastal
doi:10.21236/ada598889 fatcat:xdk5poi7ijh35p2wpfapcibh6a