Tuesday, 30 April 2002: 12:00 AM
Tropical Cyclone Wave Height Forecast Comparison using the GFDL/NWW3 Model vs the NWW3 Model
The present NCEP operational wave model for predicting global and regional ocean significant wave heights, NOAA WAVEWATCH III (NWW3), uses wind data derived from the Aviation (AVN) version of NCEP's Global Assimilation and Forecast System. Since the wind field associated with a tropical cyclone is in most cases poorly resolved by the AVN, predicted wave conditions in areas under the influence of tropical cyclones are usually under predicted. In order to provide a more accurate forecast of wind conditions, NCEP uses a separate model, the Geophysical Fluid Dynamics Laboratory (GFDL), to generate the winds surrounding a tropical cyclone. The wind fields from the various runs of the GFDL (if multiple storms exist) are run with the background wind field of the AVN to produce the associated wave field over the north Atlantic ocean. The blended AVN and GFDL model winds have been used since the 2000 hurricane season to predict wave heights surrounding tropical cyclones. A comparison will be made for the 2001 Atlantic hurricane season between the blended and unblended, i.e., only the AVN, model wind field. Using moored buoys to validate results it will be shown that the GFDL/NWW3 gives more realistic wave height forecasts.
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