Dinâmica espaço-temporal das anomalias de precipitação em uma região semiárida, Nordeste do Brasil

Abstract

Extreme weather events assume great socioeconomic relevance, especially in regions climatically sensitive such as semi-arid climate.  The analysis of the rainfall regime of a given region can be made by the Rainfall Anomaly Index (RAI), which allows classifying the rainfall regime as to the annual anomalies of precipitation, inferring on the dry and humid cycles. Therefore, the objective was to study the spatial-temporal variability of precipitations of an area inserted in the Semiarid region of Brazil. For this, the RAI was used for the climatological normal 1987-2017 of 11 rainfall stations inserted in the mesoregion of the Sertão of the state of Pernambuco. The annual and interannual precipitations were analyzed, determined the negative and positive anomalies along the climatological normal, and, through the spatial interpolation of precipitation by the Method of inverse of the Square of Distance, elaborated spatial distribution maps of rainfall in different annual anomalies. The results showed that in 90.9% of the stations studied the rainy block occurs between the months of January to April, and that the accumulated of these months corresponds to more than 50% of the precipitated annual volume, thus demonstrating the irregularity in the annual distribution of rainfall. It was found that in 55% of the years there were negative anomalies in the mesoregion of the Sertão of Pernambuco. Moreover, it was spatially verified a greater homogeneity in the spatial distribution of negative anomalies in relation to positive anomalies, that is, drought events, when they occurred, tended to reach the entire studied area.