7D.3 The Relationship Between the Air-Sea Interactions and Tropical Cyclone Intensity

Tuesday, 11 May 2010: 1:45 PM
Tucson Salon A-C (JW MArriott Starr Pass Resort)
Jamese D. Sims, NOAA/NWS/NCEP/EMC, Camp Springs, MD; and G. S. Jenkins and R. Grumbine

The Hurricane Weather Research and Forecast (HWRFTM) System is used to simulate forecast 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 impact of air-sea interactions - latent and sensible heat fluxes on the forecasting of tropical cyclone activity in the Atlantic Ocean will be discussed. Authors have shown that latent and sensible heat fluxes provide fuel for tropical cyclones as the ocean and atmosphere exchange heat energy. In this study, simulations with varying latent and sensible heat fluxes in the HWRFTM model are undertaken to evaluate the model's forecast of storm intensity and to show that latent and sensible heat fluxes play the primary role in tropical cyclone intensity.

There are 5 experiments done including the control experiment. The simulations that vary latent and sensible heat fluxes are compared to the control simulations to determine the sensitivity of the surface fluxes on the forecast of hurricane intensity. The following physical parameters are studied: precipitation rates, vertical heating rates, vertical wind profile, vertical velocity, latent and sensible heat fluxes, sea level pressure, and wind speed. The results show the impact of increasing and decreasing latent and sensible heat fluxes on the physical parameters that determine tropical cyclone maintenance and that latent and sensible heat fluxes play a primary role in hurricane intensity. It is also shown that reducing the latent and sensible heat fluxes in HWRFTM yield improved forecast for Tropical Storm Debby and Hurricane Helene.

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