South Atlantic SST anomalies impacts on the south Brazilian region climate through a numeric experiment with the model CAM 2.02 and data dining techniques

The aim of this work is to evaluate the influence of the South Atlantic Ocean (SAO) Sea Surface Temperature (SST) anomalies on the rain regimen of the South Brazilian Region and, consequently, in the local hydrographic basins. An analytical function based on a combination of two Gaussian distribution in space and one distribution in time was applied to the climatology of SST of the Community Atmosphere Model version 2.02 (CAM 2.02) of the National Center for Atmospheric Research (NCAR) in order to simulate an SAO SST anomaly. The Gaussian analytical function was adjusted to the February and March of 2005 observed anomaly in the SAO, on the region near 58W and 40S where those anomalies reached 2\ub0C. In this period a rain anomaly in the South Brazilian Region took place, with pluviometric deficits of about 100 mm in the Uruguai (SC) and Iguaçu (PR) rivers basins. In the subsequent months the SAO SST anomaly intensity was diminished but it was increased up in area reaching 20S in September, persisting until October. In these last two months the rain levels in the south region of Brazil basins exceeded the historical values in more than 100 mm. Data mining techniques applied to some computed indexes obtained from the model results revealed some South Brazilian Region circulation anomalies patterns in response to the SAO/SST anomaly forcing. The vertical structure of the model atmosphere was strongly affected by the forcing, the humidity and latent heat flux was augmented and the planetary bondary layer height was shortened in the anomaly forced region. These preliminary results emphasize the importance of the prognostics of SST in seasonal climatic forecast, demonstrating the need of a coupled ocean-atmophere modeling system for this kind of forecast.Pages: 521-53