Nested Grid Modeling of Circulation on the Inner-shelf

Donghua Cai, Georgia Institute of Technology, Civil Engineering, Atlanta, GA, United States, Kevin A Haas, Georgia Tech Savannah, Civil Environmental Engineering, Atlanta, GA, United States, Emanuele Di Lorenzo, Georgia Institute of Technology Main Campus, Program in Ocean Science & Engineering, Atlanta, GA, United States, Sutara H Suanda, University of North Carolina at Wilmington, Wilmington, NC, United States, Nirnimesh Kumar, Scripps Institution of Oceanography, Integrative Oceanography Division, La Jolla, CA, United States, Arthur J Miller, University of California San Diego, La Jolla, CA, United States, Falk Feddersen, University of California San Diego, Scripps Institution of Oceanography, La Jolla, United States and Christopher A Edwards, University of California Santa Cruz, Santa Cruz, CA, United States
Abstract:
The dynamical controls on the circulation for the inner shelf (5-30 m water depth) are complex due to dominant balances associated with the many temporal and spatial scales of surface and wave forcing along with intrinsic variability (instabilities, internal wave propagation, etc.). To shed some light on this problem, numerical simulations of the inner shelf region that roughly corresponds to the Point Sal beach off the coast of Point Conception are conducted by coupling ROMS and SWAN modules of the COAWST model system.

The model system is configured with four nested grids with resolutions ranging from approximately 600 m to the outer shelf (~200 m) to the inner shelf (~66 m) and finally to the surf zone (~22 m). A solution from a 1 km grid encompassing our domain provides the boundary conditions for the 600 m grid. Barotropic tidal forcing is incorporated at the 600 m grid to provide tidal variability. Surface gravity waves are introduced beginning at the 200 m nested grid in order to resolve the influence of wave driven currents originating in the surf zone on the process inner shelf.

The simulations focus on the time period of June – July, 2015 corresponding to an ONR pilot study in which observational experiment data was collected. The experiment data in part consists of in situ measurement, which includes mooring with conductivity, temperature, depth, and flow velocity. In addition, multiple modalities of remote sensing data was collected including land-based and aerial radar and video, which can provide information on sea surface fronts, height, and temperature and multispectral images of the biological condition. This data will be used to test the capability of our model to exhibit realistic behavior in terms of flow structures on the shelf, alongshore flows, and internal tides.

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