Key climate oscillation factors controlling precipitation variability during the dry season in eastern northeast Brazil: Study case of Mundaú and Paraíba do Meio river basins

Abstract

In Brazil, the northeastern region (NEB) is considered one of the most vulnerable areas of the country in terms of precipitation variability due to frequent drought episodes during the rainy season. Differently from the Northern NEB (NNEB), where dry season is consistently dry, the Eastern NEB (ENEB) exhibits a high interannual variability of precipitation during the dry season, including years exceeding 400 mm. This work aims at understanding key large-scale climate factors that modulate the high pluviometric variability of ENEB during the dry season. Multivariate statistical techniques were applied to identify the time-frequency relationship between precipitation variability and global climate phenomena. The results suggested that hydrological extreme events during the dry season became more frequent after the 1990s. Moreover, our findings also indicated a relationship, at multiannual time scales, between the state of El Niño Southern Oscillation (ENSO) and Atlantic Meridional Mode (AMM) and precipitation variability during the dry season. This additional knowledge may contribute to the formation of new perspectives of drought management, leading support to the development of a long-term drought forecasting framework, as well as to the improvement of the water resources management of the region.