双流机场一次副高边缘雷雨天气过程诊断分析
Diagnostic Analysis of a Thunderstorm Event on the Edge of the Subtropical High at Shuangliu Airport

利用双流机场气象自动观测资料、欧洲中心ERA5再分析资料及MICAPS常规气象资料，从天气环流形势配置、流函数和物理量诊断方面，对双流机场2023年7月11日~12日的雷雨天气过程进行分析。结果表明，此次雷雨天气是在西太平洋副热带高压西进东退演变趋势下，受副高边缘暖湿气流与高空槽等天气系统共同作用的结果。对流活动在副高外围暖湿气流与地形抬升等因素的强迫下逐渐发展，并在副高东退、高空槽东移带来的冷空气影响下加强。此次过程的对流主要发生在588线最大西伸位置边缘与流函数零线靠近负值区一侧的交叉区域。此次过程，成都终端区充足的水汽与高不稳定能量促进了雷暴活动的增强。在雷雨发生前，双流机场850 hPa的比湿 ≥ 18 g/kg，700 hPa的比湿 ≥ 16 g/kg，平均K指数为42℃，平均CAPE为2000 J/kg。
Utilizing automatic meteorological observation data from Shuangliu Airport, European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis data, and MICAPS conventional meteorological data, this study analyzes the thunderstorm event that occurred at Shuangliu Airport from July 11th to 12th, 2023, in terms of synoptic circulation patterns, stream function, and physical quantity diagnostics. The results indicate that this thunderstorm event was the combined effect of the warm and moist airflow on the edge of the western Pacific subtropical high (WPSH), which exhibited a westward-then-eastward retreat pattern, and other weather systems such as upper-level troughs. Convective activities gradually developed due to the forcing of the warm and moist airflow on the periphery of the subtropical high and terrain uplift, and intensified under the influence of cold air brought by the eastward retreat of the subtropical high and the eastward movement of the upper-level trough. The convective weather mainly occurred in the intersection area between the edge of the 588-dagpm line at its westernmost extension and the side of the stream function zero line close to the negative value region. During this thunderstorm event, abundant moisture and high instability energy in the Chengdu terminal area contributed to the enhancement of thunderstorm activities. Prior to the thunderstorm, the specific humidity at 850 hPa at Shuangliu Airport was ≥18 g/kg, the specific humidity at 700 hPa was ≥16 g/kg, the average K-index was 42？C, and the average Convective Available Potential Energy (CAPE) was 2000 J/kg.