| 17 Jul 2026
Observing Phase Transitions in Extreme Rainfall Events: Insights from Sub-Minute Observations and Universal Multifractal Analysis
Abstract. Complex systems across scientific disciplines often undergo abrupt, qualitative reorganizations –referred to as phase transitions– in which their fundamental properties change discontinuously. In geophysical contexts, such transitions can appear as sudden alternations in statistical behavior or scaling characteristics. In this study, phase transitions in extreme rainfall events are investigated through the Universal Multifractal (UM) framework, using ultra-high-resolution (10-second) disdrometer measurements collected during three typhoons in 2022: Hinnamnor, Nesat, and Nalgae. Two categories of multifractal phase transitions are examined: (i) transitions associated with sampling limitations and (ii) those related to moment divergence. While sampling limitations were observed during Typhoons Hinnamnor and Nesat, Typhoon Nalgae exhibited a clear case of moment divergence –a rare phenomenon indicative of extremely concentrated rainfall. These findings highlight the essential role of ultra-high-resolution time series in detecting and characterizing extreme hydrometeorological events. The study further demonstrates the capability of the UM framework to capture complex rainfall dynamics and offers insights that may contribute to improved hydrological modelling and flash-flood forecasting.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Nonlinear Processes in Geophysics.
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