第八届全国中尺度气象学研讨会

Extreme-precipitation-producing mesoscale convective systems (EP-MCSs) constitute a highly impactful subset of East Asian Summer Monsoon weather, yet their climatology and long-term evolutionary trends remain systematically unquantified. Utilizing an improved Iterative Raincell Tracking (IRT) algorithm on 24 years (2001–2024) of satellite infrared and precipitation products, the spatiotemporal characteristics of warm-season EP-MCSs are analyzed across three typical domains: the Sichuan Basin and surrounding regions (SCB), the Huang-Huai-Yangtze region (HHY), and southeastern China (SEC). The results showed that EP-MCSs contribute over 50% of total MCS precipitation and heavy-rainfall-event precipitation regionally, being systematically larger, longer-lived, and more intense than typical MCSs. Trend analysis reveals profound spatial divergence: EP-MCS precipitation increased significantly in the SCB and HHY, but decreased substantially in SEC. This spatial divergence is primarily controlled by shifts in EP-MCS occurrence frequency rather than intensity, physically associated with the westward extension and intensification of the western North Pacific Subtropical High during the past 24 years. Specifically, EP-MCSs in the SCB exhibit increased occurrence frequency and strengthened nighttime precipitation peaks, despite decreasing spatial areas of cloud and precipitation. EP-MCSs in the HHY display increased frequency, prolonged lifetimes, and substantially enhanced moderate-intensity rainfall. Conversely, EP-MCSs in the SEC exhibit a severe overall frequency decline and a significant reduction concentrated at the heavy-intensity spectrum, alongside weakened afternoon diurnal peaks. These findings highlight the notable region-specific sensitivities of these extreme convective systems to current climate change, providing critical observational benchmarks for evaluating convection-permitting climate models and projecting future hydrological extremes.

Mesoscale Convective Systems,Precipitation,East Asia,Extreme Precipitation,WNPSH