25th Conference on Hurricanes and Tropical Meteorology

Monday, 29 April 2002
The Impact of Dropsonde Data on Forecasts of Hurricane Debby by the Met Office Global Model
Julian T. Heming, Met Office, Bracknell, Berks., United Kingdom; and X. Qu
In August 2000 Hurricane Debby formed in the tropical Atlantic and moved west-northwestwards just skirting the northernmost islands of the Caribbean. Forecasts from the Met Office global model initially predicted that the hurricane would turn northwestwards, intensify rapidly and threaten the Bahamas and southern Florida. However, there was then a sudden change in forecast which tracked a much weaker system across Cuba into the Caribbean Sea and Gulf of Mexico. This change co-incided with reconnaissance missions by NOAA aircraft which deployed dropsondes whose data were fed into the global model. The latter forecasts proved far more skilful, as the hurricane turned westwards and dissipated rapidly in the western Caribbean Sea.

Previous data impact studies have shown that dropsondes have had a positive impact on Met Office global model hurricane forecasts. This paper evaluates the changes in forecast track and intensity of Hurricane Debby resulting from the use of dropsonde data and determines which components of the dropsonde data are more valuable to the model's data assimilation process.

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