杭州萧山机场一次短时强降水天气过程诊断分析

Diagnostic Analysis of a Short-Duration Heavy Rainfall Event at Hangzhou Xiaoshan Airport

摘要: 为提升机场极端强降水天气的预报预警能力，利用常规观测数据、欧洲ERA-5再分析资料、C波段雷达及X波段相控阵天气雷达产品，对2025年9月2日杭州萧山机场极端强降水天气过程进行诊断分析。结果表明：此次过程是在中低层切变线与边界层辐合区叠加的环流背景下发生，中低层一致的切变线配置为对流发展提供了持续动力抬升；探空环境呈现高能量、强水汽、良好抬升及高效暖云降水的协同特征；动力条件上，15~17时机场上空整层一致强上升运动与“低层辐合–高层辐散”配置增强垂直抽吸作用；水汽由低空偏南气流持续输送，925 hPa比湿从15 g·kg⁻¹升至16.5 g·kg⁻¹；热力条件上“下暖湿平流–上冷平流”配置加剧层结不稳定。雷达监测显示，天目山对流云团东移过程中形成阵风锋，触发机场偏南弱回波发展为60 dBZ脉冲风暴，该脉冲风暴并入周边对流云团后，系统逐步组织化发展，最终形成带状对流回波，维持强降水46分钟。研究结果可为机场短时强降水预报提供参考。

Abstract: To improve the forecasting and early warning capability of extreme heavy precipitation events at airports, a diagnostic analysis was conducted on the extreme heavy precipitation event that occurred at Hangzhou Xiaoshan International Airport on 2 September 2025. The analysis utilized conventional observation data, European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-5 reanalysis data, C-band weather radar products, and X-band phased array weather radar products. The results show that this event occurred under the circulation background characterized by the superposition of the middle-low level shear line and the boundary layer convergence zone. The consistent configuration of middle-low level shear lines provided continuous dynamic uplift for the development of convection. The sounding environment exhibited synergistic characteristics of high convective available potential energy, abundant water vapor, favorable lifting conditions, and efficient warm-cloud precipitation. In terms of dynamic conditions, the consistent strong upward motion throughout the atmospheric column over the airport from 15:00 to 17:00 Beijing Time, together with the configuration of low-level convergence and upper-level divergence, enhanced the vertical pumping effect. Water vapor was continuously transported by the low-level southerly airflow, with the specific humidity at 925 hPa increasing from 15 g·kg⁻¹ to 16.5 g·kg⁻¹. Regarding thermodynamic conditions, the configuration of warm and moist advection in the lower layer and cold advection in the upper layer intensified atmospheric stratification instability. Radar monitoring revealed that a gust front formed during the eastward movement of convective cloud clusters over the Tianmu Mountains, which triggered the weak echo south of the airport to develop into a 60 dBZ pulse storm. After merging with surrounding convective cloud clusters, this pulse storm gradually evolved into an organized convective system and eventually formed a banded convective echo, sustaining intense precipitation for 46 minutes. The findings of this study can provide a reference for the short-term heavy precipitation forecasting at airports.