Regionalization and Trend Analysis of Precipitation in Rio Grande do Norte Associated with SST Patterns

Abstract

Precipitation presents high spatial and temporal variability, as in Northeast Brazil (NEB), which is characterized by long periods of droughts and episodes of excessive precipitation, which influences the water resources management. Specifically, Rio Grande do Norte (RN) state located in the eastern of NEB, the rainy season occurs in two periods. In this context, the main objective of this study is to define homogeneous areas of precipitation (HAPs) in the RN state to investigate linear trends and changes in which they occurred in the rainy season. It was used the accumulated precipitation from the fourth version of data from the University of Delaware, for the period 1900 to 2014. To identify the HAPs was used the cluster analysis. Trends were estimated by the Mann-Kendall test. The structural breaks was made by the Pettitt method. The results indicate three HAPs in the RN state: West, Seridó and Coast. The rainy season in the West and Seridó is concentrated between February and May; on the coast, between April and July. Trends are identified only on the coast with p-value < 0.05, an increase in their mean was observed from 1964 and this is apparently associated with the modes of Atlantic variability.

Keywords:
Mann-Kendall; Pettitt; positive trend; rainy season