The long-term goal is to: research, integrate, demonstrate and utilize end-to-end prediction and DA systems to better study, understand, forecast and exploit environmental and acoustic fields and uncertainties for efficient sonar operations.

Specific objectives are to:

• Improve the understanding of dynamics, predictabilities and uncertainties in the southern East China Sea (ECS) and Northern Philippine Sea region
• Study, model and quantify the interactions of Kuroshio meanders, mesoscale features and internal tides and waves, based on process and sensitivity studies
• Further research coupled environmental and acoustic modeling; assimilate ocean physics, acoustic and seabed data; and, utilize data-model misfits to improve the corresponding models
• Link the regional modeling effort to larger-scale modeling, including the use of acoustic measurements in deep waters
• Design observation system properties and adaptive sampling schemes to optimize the placement of sensor systems for the reduction of uncertainty and best exploitation of the environment

End-to-end Prediction and DA Systems and their Uncertainties. An important component of this work involves the research, integration, demonstration and utilization of end-to-end prediction and DA systems for efficient sonar operations. Our research collaborations include the following components of such systems: ocean physics models (the free-surface model of MSEAS), acoustic models (NPS model and RAM), coupling schemes for these water-column and acoustic models, and the corresponding DA systems. We have extended our modeling experience and ESSE data assimilation system to seabed and signal-to-noise-ratio (SNR) modeling and assimilation, for fully coupled ocean-physics-acoustic-seabed-SNR estimations. The accounting of all system uncertainties including those of the ocean and bottom environment, and of the sonar equations, must to be accurate enough for successful end-to-end estimations (Lermusiaux, 2006a). The uncertainty estimates computed by the DA systems are evaluated by statistical analyses and comparison to data-forecast misfits. Interesting research has involved the theoretical modeling and estimation of uncertainties for idealized systems. Such idealized research has been necessary for determining the accurate representation and transfer of uncertainties across the various disciplines.

Ocean Dynamics, Features and Predictability. We are studying, modeling and quantifying ocean dynamics and features in the East China Sea (ECS) and Northern Philippine Sea region, with emphases on oceanic events that are acoustically important. Processes of interests include interactions of the meandering Kuroshio with shelf dynamics and topographic features (entrainment, encircling of ECS waters, eddying, etc) and interactions of mesoscales with internal tides and waves in the ECS.