Tidally induced internal motions are important in the coastal environment because they enhance the spatial and temporal variability of currents, mixing and biological productivity in the region. Tides interact with other dynamical processes which can result in an intermittent internal tide. Traditional observations are too sparse in space and time to resolve these processes and thus fundamental questions about them remain unanswered. In this study, oceanographers at Oregon State University plan to address questions such as whether these internal tides contribute significantly to shelf transports on the surface, interior and bottom of the ocean and how these transports compare to the wind-forced motions. In addition they will address how these tides contribute to horizontal dispersion and vertical mixing and how these processes are affected by changes in stratification and the wind-driven currents. Their goal is to determine the predictability of internal tides in the shelf environment with a specific application of the summer upwelling regime on the Oregon Shelf. The Regional Ocean Modeling System (ROMS) will be used with observations from High Frequency radars as well as moorings from recent other NSF programs such as COAST and GLOBEC. New modeling and analysis techniques will be implemented included variational data assimilation methods using the tangent linear and adjoint models and methodologies for data analysis and synthesis. The results will assist in identifying areas of intensified internal tides along the Oregon coast, which may guide the design and development of future observational programs. The study will have a broad impact because it will provide an improved numerical model for chemical and biological oceanographers and will also assist in the development of a coastal forecasting system that can serve broad public needs regarding pollution transport, search and rescue missions, fisheries, recreation and education. A graduate student will be trained in modeling and data assiilation methods.
