Design, Calibration and Validation of a Coupled Numerical Ocean Modeling System for the West Florida Shelf.

摘要

Global and basin-scale numerical ocean models run on model grids which are too coarse to resolve most bays and estuaries. Conversely, using bay and estuary resolving grids with such models would produce grids with prohibitively large numbers of grid points and the time step restrictions for running on such grids would be unacceptably strict. Therefore, model coupling (or nesting) is a reasonable way to downscale global/basin-scale models to perform high resolution computations in localized regions. Model coupling can be carried out either as a two-way nesting within the same model or by coupling two separate models sharing common interfaces through which model boundary information is passed. Due to the greater degree of flexibility associated with the latter, it is often preferred and this approach is also adopted in the present research. In this report, a ROMS-based high resolution model (NWFS-3D) for the west Florida shelf (WFS) is coupled to a POM-based, basin-scale Gulf of Mexico model (NGOM). The coupling is effected through the initialization fields and the lateral and surface boundary condition fields all of which are interpolated on to the NWFS-3D model grid from the NGOM grid. A specific boundary condition treatment for the barotropic velocities was necessary to alleviate the entrapment of barotropic waves within the NWFS-3D model domain and allowed them to be freely transmitted in and out of it. The model coupling was calibrated and validated through a 15-day NWFS-3D simulation after its bathymetry and coastline had been replaced with those of the lower resolution NGOM model. A comparison of the water elevations, currents, temperature and salinity showed that NWFS-3D was able to faithfully reproduce the corresponding fields from NGOM.