Abstract

DE SOUZA, Everaldo B.; AMBRIZZI, Tércio  and  COELHO, Caio A. S.. Two ENSO episodes with reversed impacts on the regional precipitation of the northeastern South America. Meteorologica [online]. 2004, vol.29, n.1-2, pp.5-16. ISSN 1850-468X.

Diagnostic analyses of two ENSO episodes observed during 1954-55 (La Niña) and 1972-73 (El Niño) over tropical Pacific Ocean are reported. These years were marked by reversed impact on the regional precipitation observed over the northeastern South America. The observational results showed that, in the Pacific Ocean, the La Niña stayed well configured during both summer and autumn of 1954-55, however the El Niño presented its mature phase during summer of 1972-73 and an abrupt decline during autumn of 1973. On the other hand, the large-scale oceanic and atmospheric patterns related to the intertropical Atlantic SST gradient, created dynamic conditions that modulated the positioning of ITCZ in the equatorial Atlantic and regulated significantly the rainfall anomalies observed in the northeastern South America, overcoming the effect of the ENSO mode observed in the tropical Pacific.

Keywords : ENSO; Atlantic SST Gradient; ITCZ; South America.

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