SST anomaly variability in Southwestern Atlantic and El Niño/Southern oscillation Original Research Article

The purpose of this paper is to study the relation between Sea Surface Temperature anomalies in the Southwestern Atlantic Ocean and the presence of El Niño and La Niña events, in the period 1868–2000. SST anomalies were taken from 1856–2000 Kaplan data set, and El Niño and La Niña events from different authors. Significative differences were found in the SST anomalies in the winter period (from April to October) taken at 8 points in the Southwestern Atlantic, depending on the presence of El Niño or La Niña. On an average, the El Niño events (registered in December of each year) are characterized by negative SST anomalies at the Malvinas current and positive SST anomalies at the Brazil current in the winter of the corresponding year. On the contrary, La Niña events are characterized by anomalous cold Brazil current and warm Malvinas current. Decrease of SST anomalies in Malvinas current and for preservation of its trend until October is suggested as the precursor of El Niño. Using the monthly SST anomalies in Southwestern Atlantic, statistical indicators for ENSO events were computed. These indicators are used for reconstruction of the weak, moderate strength, and strong La Niña episodes for the 1868–2000 period. El Niño (except the strongest events), could be predicted three to six months in advance from of time-space SST anomaly variability in Southwestern Atlantic.