INFLUENCES OF EL NIÑO SOUTH OSCILLATION (ENSO) AND PACIFIC DECENAL OSCILLATION (PDO) ON THE VARIABILITY OF ANNUAL RAIN TOTALS IN GOIÁS AND THE FEDERAL DISTRICT

Abstract

The exceptional rainfall regime can condition economic and social losses, especially related to human supply, food production and energy generation. In order to contribute to the understanding of rainfall variability, the objective is to analyze the influences of ENSO and PDO on the variability of annual rainfall totals in Goiás and the Federal District, based on rainfall data from 40 stations of the National Water Agency (ANA, in portuguese) and the National Institute of Meteorology. (INMET, in portuguese), between the hydrological years from 1975/1976 to 2015/2016. The rainfall data were organized and treated in order to demonstrate the absolute frequency of rainfall patterns that were related to the ENSO and PDO phases, and Student's t test was applied and the Analysis of Variance (ANOVA) was performed to determine the level of the statistical significance. The results showed that there was a higher frequency of the rainy pattern during the years considered neutral and in the El Niño condition during the warm phase of the PDO. There was a higher frequency of the dry pattern in the rainfall regions north of the study area and in the Jataí region during the La Niña condition in both phases of the PDO.