85th AMS Annual Meeting

Thursday, 13 January 2005: 2:30 PM
Tidal prediction in the Asian marginal Pacific
Ruth H. Preller, NRL, Stennis Space Center, MS; and P. J. Martin and S. K. Riedlinger
The East Asian Seas (EAS) Nowcast/Forecast system is based on the U.S. Navy Coastal Ocean Model (NCOM). The EAS encompasses the marginal seas of the western Pacific, including the South China Sea, the East China Sea, the Yellow Sea and the Japan Sea. NCOM, though similar to the Princeton Ocean model, differs in that it contains a hybrid vertical coordinate system (a combination of sigma and z-level coordinates), a selection of open boundary conditions and a selection of mixed layer formulations. NCOM, originally developed for coastal applications, has been applied globally in a nowcast/forecast mode and is being applied by the U.S. Navy in both regional and relocatable, coastal applications. The Global NCOM has a horizontal resolution of 1/8th degree. The EAS model is nested in the global model using twice the horizontal resolution (1/16th degree, or 6-9 km) and the same vertical coordinate and grid. Atmospheric forcing for NCOM, in the form of atmospheric stresses and heat fluxes, are obtained from either the Navy Global Operational Atmospheric Prediction System (NOGAPS), or from the Navy’s Coupled Oceanic and Atmopheric Prediction System (COAMPS). NCOM also includes tidal potential forcing for 10 tidal constituents. To compute tidal boundary condition forcing, NCOM stores harmonic tidal constituent elevation and depth-averaged velocity data at each of its open boundary points. These data were obtained (interpolated) from the Oregon State University (OSU)global tidal database . In the case of the EAS, these tides are applied at an open boundary that lies in the mid-Pacific in very deep water. This paper will look at the EAS Nowcast/Forecast systems ability to predict tides in the coastal regions included in the model domain. Model predictions of tidal elevation will be compared to sea level station data available from the University of Hawaii and to tidal elevation calculated from tidal constituents available from the IHO tidal database. Tidal elevation from the EAS system will also be compared to global tide model calculations from the OSU and Finite Element 99 (FES99) models.

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