Seasonal Contrasts in Hourly Wind Dynamics Across Stations in Piauí, Brazil: A Rolling Multifractal Window Approach

This paper examines hourly wind speed dynamics at 12 INMET stations in Piauí, Brazil, asking whether the local multifractal organization of the wind field moves closer to or farther from a random benchmark across meteorological seasons. The observational base is reorganized into a rolling multifractal framework with windows of 720 h observations and steps of 168 h. For each full sample and rolling window, the singularity-spectrum peak is translated into a stochastic inefficiency index equal to its absolute distance from 0.5, so lower values indicate greater stochastic efficiency. The analysis combines this index with mean wind speed and with the empirical third moment of speed, [Formula: see text], proportional to mean wind power density under constant air density. Full-sample results identify PIRIPIRI, GILBUES, and TERESINA as closest to the random benchmark, whereas PARNAIBA is the most resource-rich station and the most structurally distant from that benchmark. Rolling results reveal marked seasonality: mean stochastic inefficiency is highest in autumn (0.2820) and lowest in winter (0.2488). Fixed-effects and quantile regressions show that winter and spring reduce stochastic inefficiency relative to summer, whereas autumn is statistically indistinguishable from the summer benchmark in most specifications. Overall, GILBUES, CANTO DO BURITI, OEIRAS, and CARACOL provide the most balanced combination of wind-resource magnitude and stochastic efficiency in the active 12-station subset.