Cross-regional impact of land and ocean evaporation on extreme precipitation in North China

North China (NC) This study investigates the changing characteristics and driving mechanisms of summer extreme precipitation in NC (1979–2023). Using CN05.1 and ERA5 data, we employed Self-Organizing Map (SOM) analysis to identify atmospheric circulation patterns associated with 207 extreme precipitation days. The research determines the long-term trends of these circulation regimes and quantitatively diagnose the causal linkages between antecedent terrestrial evaporation and extreme precipitation using the Liang-Kleeman Information Flow (LKIF) method. The analysis identifies four distinct circulation patterns, revealing that the upward trend in NC extreme precipitation is dominated by two "east-side high-pressure" types (56 % of events), which have significantly increased in frequency. These events are governed by a northward-shifted Western Pacific Subtropical High (WPSH) and mid-high latitude high-pressure belts. In contrast, "trough-type" events driven by northern vortices have declined. A key novelty is the identification of cross-regional terrestrial evaporation as a critical precursor signal. Specifically, LKIF analysis demonstrates that terrestrial evaporation from the Middle-Lower Yangtze River Basin (MLYRB) causally contributes to high-pressure type events with a 1–2 day lead time, whereas trough-type events derive terrestrial moisture mainly from South China with a 3–4 day transport lag. Collectively, these findings highlight that antecedent terrestrial moisture in southern China serves as a robust precursor signal for forecasting extreme precipitation in NC. • High-pressure anomaly off East Aisa boosts North China’s extreme precipitation. • Enhanced southern evaporation precedes most North China extremes by 1–2 days. • Information flow confirms land moisture as a precursor to North China's extreme rain.