Dynamic Identification of Tropical Cyclone Precipitation Peaks and Regional Sensitivity Assessment in Eastern China (2004–2023)

Based on precipitation observations and tropical cyclone best-track data from 2004 to 2023, this study developed a technical framework integrating dynamic threshold identification and spatial heterogeneity assessment to systematically analyze the spatiotemporal differentiation patterns and sensitivity characteristics of tropical cyclone precipitation in eastern China. The results indicate that the highest precipitation contribution occurs during the mid-landfall period (T0 to T+1 days), with a mean contribution rate of 58.38%, followed by the post-landfall period (T+2 to T+3 days) at 25.93%. Coastal provinces exhibit rapid precipitation response, with the shortest daily precipitation peak lag periods observed in Hainan, Fujian, and Zhejiang. In contrast, inland provinces generally show lags exceeding 3 days, with Heilongjiang, Inner Mongolia, and Jilin recording the longest delays. Hourly precipitation peaks lag tropical cyclone landfall by 3.62, 6.23, and 6.31 hours in Hainan, Fujian, and Zhejiang, respectively, while Heilongjiang experiences a maximum lag of 84.88 hours. The highest extreme precipitation thresholds are concentrated in southeastern coastal regions, with significantly elevated thresholds at specific stations in northern inland provinces (e.g., Beijing and Liaoning). Extreme precipitation events predominantly cluster between T0 and T+2 days, with Guangdong, Zhejiang, and Fujian ranking highest on T0. High coefficients of variation (Cv) for daily precipitation extremes are concentrated in Shanxi (Yangquan Station) and Hebei (Xingtang Station). Northern inland regions exhibit significant increases in extreme precipitation trends, and comprehensive sensitivity indices (S) in North China and the middle Yangtze River basin (Shandong, Beijing, Henan, Chongqing) are notably elevated, with a mean value of 0.46. Spatial autocorrelation analysis revealed contiguous high-sensitivity hotspot clusters in the North China Plain, while significant cold spot clusters were identified in the inland Northwest and southeastern coastal regions.