Generation of Synoptic Water Level and Depth-Averaged Velocity Time Series on the Delaware Bay for Use in Model Coupling

The National Ocean Service has developed a platform for systematic hydrodynamic model testing and validation called the Model Evaluation Environment, based on circulation observations in Delaware Bay. In order to specify boundary conditions for the environment, the Advanced Circulation finite element model (ADCIRC) is applied to compute shelf-scale circulation. A variably graded mesh of the Western North Atlantic is used to provide water levels and currents around the perimeter of Delaware Bay. The North American Regional Reanalysis product provides meteorological forcing during a 1984 hindcast period. Testing with a range of domains, grid resolutions, and meteorological inputs demonstrates the highly non-dissipative ADCIRC model's sensitivity to reflection of waves at the open ocean boundary. Furthermore, use of an elevation-specified (`clamped') boundary condition with meteorological forcing leads to model instability due to reflection of the atmospheric pressure inverse barometer signal. This problem is mitigated by moving the boundary well away from the region of interest into the deep ocean, and by tapering the atmospheric pressure anomaly to zero at the open ocean boundary.