An analysis of the environmental energetics associated with the transition of the first South Atlantic hurricane

Abstract

This study presents the first analysis of the energetics associated with a hybrid cyclone's transition in the Southern Hemisphere, Hurricane Catarina (March 2004). Catarina has earned a place in history as the first documented South Atlantic hurricane, but its unusual tropical transition is still poorly understood. Here we show that Catarina's transition was preceded by marked environmental changes in the Lorenz energy cycle, with an abrupt shift from a baroclinic to a predominantly barotropic state. Such changes help to explain the unusual vortex's growth until its transition was completed. Although the vortex's energy flux is not explicitly calculated, a likely mechanism linking the enviro..