Identification and formation mechanisms of harvest-disrupting rain events in winter wheat based on an intensity–size–duration model

North China Plain, the major winter wheat-producing regions of China. Harvest-disrupting rain events (HDREs) pose a significant threat to mature winter wheat by inducing premature germination and mildew. Despite their critical impact, systematic studies on the identification and formation mechanisms of HDREs remain limited. This study proposes an innovative three-dimensional ISD identification framework—integrating intensity, spatial extent (size), and temporal duration—for accurately detecting HDREs in major winter wheat-producing regions of China. The circulation mechanisms underlying HDREs are revealed through diagnostic analysis, with the 2023 HDRE serving as a representative case. The model advanced traditional single indicator methods with a recognition rate of 100 %, successfully identifying all historical HDRE records. For regional HDREs with a comprehensive intensity exceeding 0.5, the model attains a threat score of 0.71, demonstrating strong detection capability and accurate characterization of event features and overall intensity. Circulation patterns associated with HDREs are classified into four primary types: blocking high-pressure , three-trough and two-ridge , latitudinal, and North China cold vortex, with the blocking high-pressure type being the most dominant, accounting for 63.9 % of cases. The high-impact HDRE that occurred in 2023 fall into the blocking high-pressure category, primarily driven by persistent blocking highs combined with super typhoons, which jointly contributed to the anomalous westward and northward displacement of the western Pacific subtropical high. • Developed a novel three-dimensional ISD model for harvest-disrupting rain events (HDREs) detection. • Systematically clarified the dominant circulation patterns and formation mechanisms of HDREs. • Representative 2023 HDRE case reveals insurance losses and circulation dynamics .