Variability of rainfall and temperature (1912–2008) parameters measured from Santa Maria (29°41′S, 53°48′W) and their connections with ENSO and solar activity

In this work, we analyze the long term variability of rainfall and temperature (1912–2008) of Santa Maria (29°S, 53°W) and its possible connection with natural influences such as solar activity and ENSO. Temperature and rainfall present similar frequencies as revealed by spectral analyses. This analysis shows a large number of short periods between 2–8 years and periods of 11.8–12.3, 19.1–21.0, and 64.3–82.5 years. The cross correlation for rainfall and temperature versus Southern Oscillation Index (SOI) have higher cross-power around 2–8 yr. Rainfall and temperature versus sunspot number (Rz) showed higher cross-power around the 11-yr solar cycle period. A high and continuous cross correlation was observed for Rz-22 yr versus rainfall and temperature. Furthermore, the power between 22-yr solar cycle and meteorological parameters was higher than that obtained with the 11-yr solar cycle, suggesting that the effect of Hale cycle on climate may be stronger than the Schwabe cycle effect. These results indicate that the variability of rainfall and temperature is closely related to the variation of the Southern Oscillation Index and solar activity, and that the El Nino Southern Oscillation and solar activity probably play an important role in the climate system over Southern Brazil.

► Temperature and rainfall present similar frequencies as revealed by spectral analyses.
► In low frequencies, the Hale cycle is an important factor in the climate modulation.
► The effect of the Schwabe cycle is also statistically significant.
► In high frequencies ENSO is the main influence on climate variability.