Study on spatiotemporal variation characteristics of regional extreme precipitation and its driving factors in geography and atmospheric circulation: Case study of Poyang Lake Basin

Study region The Poyang Lake Basin, the largest freshwater lake system in China. Study focus Using the CHM_PRE daily precipitation dataset for 1961–2022, this study investigates the spatiotemporal variability and periodicity of extreme precipitation in the Poyang Lake Basin and examines its associations with geographical factors and large-scale atmospheric circulation, untangling non-stationary circulation relationships, and spatial explanatory factors. New hydrological insights for the region Extreme precipitation in the Poyang Lake Basin exhibits marked spatiotemporal heterogeneity. Spatially, intensity- and threshold-based indices generally decrease from northeast to southwest, whereas high values of frequency-based indices are concentrated in the northwest. Geographic Detector results show that the circulation-response factor and longitude have relatively strong single-factor explanatory power, while the interaction between longitude and elevation yields the highest explanatory power for RX5day (Q = 0.96). Temporally, most extreme precipitation indices exhibit fluctuating upward trends and a dominant 2–4 year interannual periodicity. ENSO, AMO, and NAO show distinct statistical associations with extreme precipitation: El Niño conditions and warm AMO phases are associated with higher extreme precipitation, whereas NAO exhibits predominantly anti-phase relationships at interannual timescales. Collectively, the results suggest a cross-scale pattern in which large-scale ocean–atmosphere variability is linked to temporal fluctuations in extreme precipitation, while geographical interactions contribute to its spatial heterogeneity. From a regional hydrological perspective, the contrasting spatial patterns of precipitation intensity and frequency imply differentiated rainfall-driven flood risks across the Poyang Lake Basin, while the identified large-scale climate associations provide foundation for seasonal hydroclimatic risk assessment and preparedness.