Rainfall is rough
This study addresses the challenge of modeling the clustering and long-range dependence of rainfall processes across multiple timescales by proposing a novel framework based on a critical Hawkes point process. For the first time, a heavy-tailed power-law kernel is introduced into rainfall modeling, unifying the Bartlett–Lewis and Neyman–Scott models to effectively capture rain cell clustering characteristics. By integrating high-frequency (minute-level) observational data with millennial-scale tree-ring proxy records and employing fractal analysis alongside Hurst exponent estimation, the work reveals a shared extremely rough fractal structure—characterized by Hurst exponents between 0.01 and 0.1—spanning from meteorological to paleoclimatic timescales. The proposed method significantly outperforms classical models at fine temporal resolutions and establishes a novel interdisciplinary link between atmospheric science and financial microstructure theory.