Detecção de tendências de mudanças climáticas para os Estados da Bahia e Sergipe por meio de índices pluviométricos diários.

Abstract

The objective of this study was to investigate way statistical the precipitation climate variability in monthly and seasonal scales from the states of the Bahia and Sergipe. The precipitation diaries data were used. Starting from that: to supply a space distribution of the rains; to compute the unconditional and conditional probabilities of first order; to calculate indexes of detection of climate changes, defined by the WMO to detect tendencies of changes in the climate of an area; to evaluate the relationship of the most significant indexes with the anomalies of sea surface temperature of the Pacific and Atlantic oceans. For so much, the precipitation diaries data were used regarding a period of 45 years of 75 meteorological stations supplied by the old net of the SUDENE available in the DCA. These data were complemented with information from ANA, DNOCS and INMET. The data presented reliable quality and represent practically all the regions of the area of study. It was also used data of the anomalies of SST obtained through NOAA. The results show that the west of the area of study is the more favored with the precipitation in the summer, happening the opposite of this in the winter; the east is more beneficiary in the winter, the south in the spring, and the north in the autumn. Influence of SST of the Pacific and Atlantic oceans is evidenced about the precipitation of the studied area, identifying like this, that the performance of ENOS and of the dipole of the Atlantic have relative influence on the climate of the Brazilian Northeast. It was obtained that the unconditional probability, P(W) , in the coastal area, it is influenced by the high readiness of humidity of Atlantic Ocean and by the generation of systems that provoke precipitation due to the contrast of temperature of the surface ocean-continent, particularly during the months of autumn and spring. In the summer the oceanic effect is not noticed due to the high humidity readiness on the researched area and the high observed persistence of the daily precipitation is associated with the nuclei of maxims precipitations that stand out in the summer, while in the winter the low persistence was predominant. A decrease of CWD was verified; increase was observed in the number days with rain, and these with larger daily intensity; therefore, the amount of annual total precipitation increased. These climate alterations happened in the researched area suggest that you/they are due to the changes in the global climate, however, precautionary to affirm that it is not possible to validate categorically that, given that, a lot of places presented tendencies positive or negative in all the examined indexes, consequently, these are also related to regional aspects.