Long-term correlations and cross-correlations in wind speed and solar radiation temporal series from Fernando de Noronha Island, Brazil

We analyze correlations and cross-correlations in wind speed and solar radiation temporal series recorded at the Island Fernando de Noronha in northeastern Brazil, using Detrended fluctuation analysis (DFA) and Detrended cross-correlation analysis (DCCA). We find that both processes exhibit persistent long-term power law correlations as well as persistent long term cross correlations. The observed persistency is found to be stronger for wind speed then for solar radiation, as indicated by higher value of the scaling exponent. By applying DFA on sliding windows of 365 day duration, we find that persistency is preserved for these windows along the entire studied period. In the periods when the decrease in correlation exponent for wind speed is observed, solar radiation shows increased persistency (higher values of correlation exponent) indicating the existence of certain complementarity between persistence property of the two stochastic processes.