69 The sea state influences on the hybrid cyclone Catarina development by atmosphere-wave coupled models

Monday, 9 July 2012
St. George (Westin Copley Place)
Ronaldo Maia de Jesus Palmeira Palmeira, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; and P. L. S. Dias and A. C. P. D. A. Palmeira

Experiments has been performed using a coupled atmosphere-wave system to investigate sea state influences on the hybrid cyclone Catarina development on the western South Atlantic in March 2004. A coupled atmosphere/ocean modeling system, which consists of the Brazilian Regional Atmospheric Modeling System (BRAMS) for the atmospheric component and the wave model Wave Watch III (WW3) for the ocean surface, was developed through a simplified communication interface between the models. This interface allows to analyze separately the sea state and the wind drag by changing the intensity of roughness length, and the sea spray effect by droplets ejected into the air through sea spray heat and momentum fluxes parameterizations added to surface heat fluxes from atmospheric model. The Catarina Hybrid cyclone was a complex went through a not yet fully understood development process. It began as an extratropical cyclone, and, through a tropical transition, the system steered back westward towards the Brazilian coast and made its landfall as a hurricane intensity system on March 27, 2004. It became the first registered hurricane in the Atlantic South. By separating influence factors, experiments were made in order to quantify both the individual contribution of wave drag to the wind and sea spray on surface fluxes, and the contribution caused by the interaction of these factors to the wind velocity, sea pressure and the associated precipitation fields.
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