VDatum for Chesapeake Bay, Delaware Bay, and Adjacent Coastal Water Areas: Tidal Datums and Sea Surface Topography.

摘要

An application of the vertical datum transformation software tool, VDatum, is developed for Chesapeake Bay, Delaware Bay, and adjacent coastal waters. Conversions between various tidal datums fields and mean sea level as well as between mean sea level and North American Vertical Datum of 1988 (NAVD 88) were developed for this VDatum application and are presented here. The tidal datums fields were derived from hydrodynamic simulations using the twodimensional, barotropic hydrodynamic model, ADCIRC. A triangular finite-element grid consisting of 318,860 nodes and 558,718 cells was created. The model was forced with nine tidal constituents (M2, S2, N2, K2, K1, P1, O1, Q1, and M4) for a 60 day simulation. Water level harmonic analysis was conducted for 37 tidal constituents. Time series over the entire Nation Tidal Datum Epoch (1983-2001) were reconstructed from the harmonic constants. Various tidal datum fields, including mean lower low water (MLLW), mean low water (MLW), mean high water (MHW), and mean higher high water (MHHW), were derived from these reconstructed time series. Model results were validated by comparing with observations from 298 water level stations maintained by the NOAAs Center for Operational Oceanographic Products and Services (CO-OPS). Discrepancies between model results and datums derived from observations were attributed to model errors and interpolated over the whole model domain using the tidal constituent and residual interpolation (TCARI) software to obtain a domain wide error field for each of the tidal datums. The error fields were applied to the direct model results to achieve errorcorrected tidal datums on the unstructured grid. Finally, tidal datum fields were interpolated onto a regular VDatum marine grid.