Rainfall extremes and drought in Northeast Brazil and its relationship with El Niño–Southern Oscillation
Micejane da Silva Costa, José Francisco de Oliveira‐Júnior, Paulo José dos Santos, Washington Luiz Félix Correia Filho, Givanildo de Góis, Cláudio José Cavalcante Blanco, Paulo Eduardo Teodoro, Carlos Antônio da Silva, Dimas de Barros Santiago, Edson de Oliveira Souza, Alexandre Maniçoba da Rosa Ferraz Jardim
Abstract
Abstract The objective of this study was to evaluate the annual standardized precipitation index (SPI) obtained from the DrinC software based on multivariate analysis in the identification of rainfall and drought extremes in the State of Alagoas and its relationship with El Niño–Southern Oscillation. Monthly rainfall data from 1960 to 2016 from National Water Agency were analysed. Annual SPI (SPI‐12) has been designed for comparison with ENSO phases via Oceanic Niño Index for 3.4 region and in identifying climate extremes in the State of Alagoas. The principal component analysis and cluster analysis techniques were applied to the rainfall series of SPI‐12. Extreme events were identified in both rainy and drought periods according to SPI‐12, and were associated with the ENSO phases (El Niño, La Niña, and Neutral). The first four principal components explained 46.68% of the variance. Our findings are crucial for agriculture and civil defence since northeastern Brazil has several areas of risk and social vulnerability.