Analyzing the inter-annual variability of rainfall in the Brazilian semi-arid region

Abstract

This research aims to analyze the interannual variability of rainfall and the correlation between solar cycles and teleconnections with the precipitation regime of the Intermediate Geographic Region of Caicó (IGRC), in the semiarid region of the state of Rio Grande do Norte, northeast Brazil. For the analyses, three time-series were used, 1913 to 2020 for the relationship between rainfall and sunspots; and both 1950 to 2020 and 1982 to 2020 for the relationship between rainfall and teleconnections (El Nino Southern Oscillation - ENOS, Atlantic Dipole and sunspots). For the data analysis, basic statistical techniques, nonparametric statistical tests such as the Mann-Kendall and the Pearson correlation coefficient were used. Results have shown that the correlation between sunspots and rainfall was -0.2, indicating a weak negative correlation (1913-2020), with a confidence level of 95%. For rainfall and ENSO (Niño 1+2 and Niño 3) it was 0.4, with a 99% confidence level for Niño 1+2, 0.3 for Rainfall and North Atlantic (TNA), and 0.3 for sunspots and rainfall with a 95% confidence level (1982 to 2020). There was no trend in rainfall values in the last century. It was concluded that the patterns of sunspots, ENSO, and the Atlantic dipole were correlated with precipitation levels in the IGRC, and studies on teleconnections and extraterrestrial factors need to be further explored to try to understand the genesis of rainfall in various parts of the globe.