Impact of extreme climatic events in the Pacific (El Niño, EN; La Niña, LN) and Atlantic (Meridional SST Gradient, GRADM) on the rainfall ofthree sub-regions over the Northeast Brazil - NEB (Northern NEB, Eastern NEB and Centre/Southern NEB) are evaluated during the period 1948 to 1997. The analysis includes observed precipitation data and simulated rainfall outputs derived from the ARPEGE Atmospheric General Circulation Model (AGCM). The results show that the precipitation over the three sub-regions presents a high variability independent of LN or EN episodes, with a predominance of dry (wet) years in the sub-regions Eastern and Northern of NEB before (after) 1976, i.e. when LN (EL) episodes were more numerous. The interannual rainfall response is stronger when GRADM is positive (inducing dry NEB) or negative (inducing wet NEB), thus showing a stronger climatic influence of the Atlantic vs. the Pacific. Combining simulated influences of Pacific and Atlantic as well as observed precipitation data over the entire period, it was found that during EN years the global tropical ocean is responsible for the rainfall variability over the NEB (especially in the Northern and Eastern sub-regions). On the other hand, during LN years, the Atlantic tropical Ocean is the main contribution, and the tropical Pacific Ocean influence is relatively modest.
Rainfall; Northeast Brazil; AGCM; Extreme climatic events
