Metocean Modulators Of The First Recorded South Atlantic Hurricane: Catarina

In March 2004, the first-ever documented South Atlantic Hurricane, Catarina, made landfall in southern Brazil. Here, we apply the genesis potential index (GPI) to give a quantitative diagnostic of the contribution of the environmental factors known to be linked to tropical cyclogenesis on Catarina's modulation. The results indicate two regions of large positive GPI anomalies: where Catarina (1) developed subtropical cyclone structure and underwent tropical transition, and (2) acquired hurricane status. We also examine the ocean's potential to sustain tropical cyclone intensification through the ocean heat content (OHC). Although some areas of positive OHC anomalies may have indicated conditions favorable to cyclogenesis, it was not sufficient to explain the main stages of Catarina's development. On the other hand, the GPI in March 2004 was the highest among March of all years (1990-2019), suggesting that this may be a valid index for obtaining a threshold for tropical cyclogenesis in south/southeastern Brazil.