Spatiotemporal variation in rainfall predictability in Serbia under a changing climate

Abstract. This study examines whether the predictability of precipitation dynamics in Serbia has been influenced by climate change. We apply Generalized Weighted Permutation Entropy (GWPE) to evaluate the temporal structure of daily precipitation series using the parameter q, which filters subsets of small (q < 0) and large (q > 0) fluctuations. The analysis covers data from 14 weather stations between 1961 and 2020.

Entropy values for q = 0 and q = 2, corresponding to Permutation Entropy and Weighted Permutation Entropy respectively, remained stable spatially and temporally. In contrast, GWPE values for q = -10 and q = 10, representing the predictability of small and large fluctuations, exhibited significant spatial and temporal variation between two 30-year subperiods. Entropy values for q = -10 were consistently lower, indicating that small precipitation fluctuations are more predictable than large ones. In several locations, significant changes in entropy occurred despite relatively stable annual precipitation amounts. In others, annual totals varied while entropy remained constant. These findings suggest that climate change has influenced the predictability of precipitation in Serbia. By filtering fluctuations across scales, GWPE effectively reveals underlying changes that may be masked by standard statistical measures.