Chen, Changsheng, et al. [Presented by Bob Beardsley]
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Abstract
This report highlights recent work done on four components of the Gulf of Maine (GoM) FVCOM integrated model system by the following team: C. Chen, G. Cowles, D. Stuebe, S. Hu, Q. Xu and P. Xue (UMASSD); R. Beardsley, C. Davis, R. Ji and D. Limeburner (WHOI); and P. Rizzolli and J. Wei (MIT).
Meteorological forcing: The GoM Mesoscale Meteorological Model (MM5) used to drive the GoM FVCOM has been replaced by the new generation community mesoscale Weather Research and Forecast (WRF) model. WRF is a finite-volume model with improved time integration and advection schemes. Initial comparisons of WRF and MM5 forecast winds at GoM weather buoys show an improvement (~10-15%).
3rd generation GoM FVCOM grid: A new higher-resolution unstructured grid has been developed for the GoM FVCOM model system. Key improvements over the 2nd generation grid include: extension to the eastern end of the Scotian shelf; maximum depth in slope region set to 1500 m; and higher resolution in coastal areas and along the shelf break and upper slope. To minimize errors caused by the sigma coordinate over sloping topography, a generalized terrain-following coordinate system has been added to FVCOM. Initial comparisons of 2nd and 3rd generation model currents at GoMOOS buoy E for 1998 show some improvement in current prediction at 2 and 50 m, especially during strong wind events.
Data Assimilation Experiments: A suite of Kalman Filters was recently implemented into the FVCOM system to allow data assimilation. Initial experiments using Optimal Interpolation (OI) and the ensemble Kalman Filter (EKF) to assimilate existing hydrographic (T/S) data into the 1998 hindcast show significant differences. Evaluation of these experiments is underway.
Northeast Ocean Forecast System (NeCOFS): An operational forecast system (NeCOFS) based on the coupled GoM WRF/FVCOM system has been setup and is now in preliminary testing. At this time, the system is running and producing 3-day forecasts of the surface weather and ocean fields every day. After further development (including better freshwater input along the coast) and evaluation, the 3-day forecast fields will be posted on the web for public use. See website: http://fvcom.smast.umassd.edu for more information about these and other projects.