5A.7 The Relationship Between Air-Sea Interactions and Tropical Cyclone Intensity Associated with the 2006 AMMA Field Experiment

Friday, 13 November 2009: 3:25 PM
Jamese D. Sims, Howard University, Washington DC, and NOAA/NWS/NCEP/EMC/MMAB, Camp Springs, MD; and G. S. Jenkins and R. Grumbine

The Hurricane Weather and Research Forecasting (HWRF) model is used to simulate forecasts of Tropical Storm Debby (August 24 - August 26) and Hurricane Helene (September 15 - September 20) in the 2006 Atlantic Hurricane Season. The model is uncoupled and initiated with GFS forecasting. The HWRF model control run gives an overestimate of tropical cyclone intensity for both Tropical Storm Debby and Hurricane Helene. Various authors have shown that latent and sensible heat fluxes are the fuel for tropical cyclone genesis and maintenance. In this study, simulations with varying latent and sensible heat fluxes in the HWRF model are undertaken to evaluate the model's forecast of storm intensity. Latent and sensible heat fluxes are reduced and increased to show their effect on various parameters of tropical cyclone activity. The experiments have shown that there is a relationship between the surface latent and sensible heat flux initial values and the prediction of tropical cyclone intensity. Reducing the amount of latent and sensible heat fluxes at the initial conditions of the model portray a more realistic view of the intensity of Tropical Storm Debby and Hurricane Helene. The relationship between these surface fluxes and wind speed, mean sea level pressure, convection, precipitation rates, and vertical heating rates are closely examined.
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