Andrea Rapisarda ^1* Vera Pecorino ¹ Alessandro Pluchino ¹ Kateřina Hlaváčková-Schindler ²

• ¹ University of Catania, Catania, Italy
• ² University of Vienna, Vienna, Vienna, Austria

Sicily island has displayed unusual rainfall behavior and unexpected extreme precipitation events during the last decades. In this paper, we investigate the Granger causal (GC) dependencies in the precipitation measurement sites network of Sicily island at different timescales (every 10 minutes, 1 hour, 6 hours, 12 hours and 24 hours). We study, across seasons and years, different parameters characterizing the GC dependencies: nodes total in/out degree, nodes total in/out strength, network total number of links, number of eastward/westward links, strength of eastward/westward links and link's maximum strength. Then, we investigate the GC-statistics intensities, focusing on the temporal evolution of maximum values over multiple timescales. Our study of precipitation patterns in Sicily indicates that, since 2013, the southern regions near Mount Etna (Catania, Siracusa, Ragusa) have exerted increased influence, while western areas (Trapani, Palermo, Agrigento) have been the most affected. Granger causality networks reveal scale-invariant dependencies, with stronger and sparser connections as timescales that extend beyond 6 hours with a notable westward flow of predictive information. These patterns, consistent across seasons, suggest localized perturbation fronts, with stronger links indicating more significant influence on predictions westward. This study highlights shifts in Sicily's water cycle, calling for adaptive management strategies in light of increasing frequency of extreme events.