Caracterização das chuvas de João Pessoa e os padrões de circulação atmosférica associados a eventos extremos.

Abstract

To know the variability of the precipitation helps to understand as the intense rain events can change in intensity and frequency before the perspective of climatic changes, in view of its potential in causing adverse impacts in the society. The research objective is to know the variability of the precipitation in annual, monthly and daily scale, to characterize the rain regimen and to carry through the rainfall classification in accordance with the Technique of the Percentiles, the city João Person, with focus in the extreme events rains and to identify related standards of the atmospheric circulation with such events. The period of study is of 1961 the 2017. The Technique of the Percentiles determined the rainfall class of the annual precipitation, that characterized the annual totals in five classrooms: Dry (D), very Dry (VR), Normal (N), Rainy (R) and Very Rainy (VR). This classification was analyzed together with periods where if the woollen occurrence La Niña registered (LN) and of El Niño (EN) and the results had not evidenced the influence of these phenomena on the variability of the rain of João Person. In the monthly classification, the maximum frequency of the Rainy and Very Rainy months occurs in the months of June and July, while in October, November and December the maximum frequencies of the Dry and Very Dry classes occur. The technique made possible identification of the extreme rain events with equal or superior daily value 60mm to it. With the 97th percentile, 272 extreme rainfall events precipitation events had been identified. To get the circulation standards the method of the Principal Component Analysis (PCA) rotated was used and applied the data of reanalysis of reduced pressure to the mean sea level (PNMM), also it used statistical techniques of Cluster Analysis (CA) and Correlation in the factors generated for the ACP. With the calculation of the 97th percentile (P97), 272 extreme precipitation events were identified, with a daily value equal to or greater than 60mm and maximum frequency from April to July (rainy four months).Data were also used for the Reduced Pressure at the Mean Sea Level (PNMM), obtained from the reanalysis data set, to identify atmospheric patterns associated with extreme precipitation events through Principal Component Analysis (PCA). The results had identified five (05) types of Standard that represent 77% of the data approximately. The dominant standard (23.93%) identified to standards in the low levels with indicative configuration of the presence of the Intertropical Convergence Zone, (ITCZ) and the high domain of North Atlantic subtropical high (NASH), South Atlantic (SASH) and South Pacific (SPSH). As the Standard (16.21%) also is associated the ITCZ, however situated more to the North of the northeast coast and an intensification of the SASH. In another Standard (14.50%) one observes the domain and intensification of a high-pressure nucleus in the subtropical area of the Atlantic including regions of Brazil, and a high-pressure nucleus in the North Atlantic, if extending until the Gulf of Mexico, in this standard also a center of low pressure is seen that dominates the Pacific and southwestern part of the South America South.