Periodicidades na distribuição homogênea da precipitação no Agreste de Pernambuco

Abstract

A B S T R A C TSince rainfall is a fundamental climatic element because it has a direct influence on agricultural production and because it is a periodic phenomenon, it can be described using harmonic analysis. The objective of this work was to apply the Fourier series harmonic analysis technique for the identification of cyclical components of annual mean precipitation variations of 71 meteorological stations distributed in six mesoregions of Agreste region of Pernambuco in Northeast Brazil. The technique of cluster analysis was applied in the identification of homogeneous regions regarding the rainfall distribution for these same meteorological stations and contributes to studies of climatic risks in agriculture. A historical series of data of 33 years, corresponding to the period of 1984 to May of 2017, of the average annual precipitation of several meteorological stations in the six mesoregions of the Agreste region of Pernambuco, consisted by the union of 71 municipalities, yielded by the Agronomic Institute (IPA) and by the Superintendence of Development of the Northeast (SUDENE). The results indicated a proper performance of the complete model consisting of three sine waves as a diagnosis of the average annual precipitation, considering the climatic characteristics of the region. The harmonics were: 16.5 years with 12% of representatively, 4.71 and 2.75 years with 12% and 25%, respectively, where the sum of the three waves explains 49% of the total rainfall variation over of the 33 years of Agreste region of Pernambuco. The hierarchical grouping analysis allowed to identify three similar pluviometrical areas, located in six microregions representative of the climatic diversity of the territory of the Agreste Southern region of Pernambuco.