17A.l NUMERICAL SIMULATIONS OF HURRICANE-OCEAN INTERACTION WITH A HIGH RESOLUTION COUPLED MODEL

The topic of tropical cyclone-ocean interaction has received increased attention in the tropical meteorology community over the past several years. It is widely recognized that the major energy source for tropical cyclones is the evaporation from the ocean. The sea surface temperature (SST) is a crucial parameter in this process. A negative feedback mechanism in the tropical cyclone-ocean system affects the SST. Namely, as the tropical cyclone strengthens the increasing winds will generate strong turbulent mixing in the upper ocean, causing significant decreases in the SST due to entrainment of the cooler waters from the thermocline into the mixed layer. The observed SST anomalies induced by the tropical cyclone have been observed to vary from 1°C up to BoC (e.g., Black, 1983). The cooling of the sea surface results in reduction in the total heat flux directed into the atmosphere leading to a decrease in storm intensity. In order to simulate the hurricane-ocean interaction during passage of a hurricane over the open ocean, the GFDL 18-level triply-nested movable mesh hurricane model was recently coupled with a multi-layer high resolution primitive equation ocean model. The hurricane model spanned 55 degrees in both the latitudinal and longitudinal directions. The innermost grid, with finest resolution of one-sixth degree, moved with the hurricane and covered an area of about 8 degrees square. The ocean model consisted of 8 layers with uniform horizontal resolution of one-sixth degree. Coupling between the hurricane and ocean model was carried out by passing into the ocean model the wind stress, heat and moisture fluxes computed in the hurricane model. The new SST calculated by the ocean model was then used in the hurricane model.