贵阳机场一次雨雪天气形成机制分析

Analysis on the Formation Mechanism of a Rainy and Snowy Weather at Guiyang Airport

摘要: 利用ECMWF ERA5再分析资料、贵阳机场地面观测资料，分析了2022年1月28日~2月2日贵阳机场雨雪期间的环流形势及物理量场。结果表明：1) 500 hPa南支槽，700 hPa西南急流，850 hPa切变线为贵阳机场此次过程提供了有利的环流背景；2) 降雪湿层最高，雨夹雪次之，冻雨湿层最低；降雪云顶温度最低，雨夹雪次之，冻雨云顶温度最高；降雪、雨夹雪温度层结整层均为冷性结构，冻雨存在逆温层、呈“冷–暖–冷”分布；3) 降雪、雨夹雪、冻雨期间贵阳机场比湿大于3.5 g/kg、水汽通量散度小于0，水汽充沛；垂直速度小于0，上升运动显著；低层(高层)水汽通量散度小于(大于)0、水汽辐合上升(辐散)。

Abstract: According to the ECMWF ERA5 reanalysis data, the ground observation data of Guiyang Airport, the circulation pattern and physical quantity field during rain and snow period from January 28 to February 2, 2022 at Guiyang Airport were analyzed. The results show that: 1) the south branch trough of 500 hPa, southwest jet stream of 700 hPa and shear line of 850 hPa provide favorable circulation background for the process of Guiyang Airport; 2) the snowfall wet layer is the highest, followed by sleet, and the freezing rain wet layer is the lowest. The temperature of snowfall cloud top is the lowest, followed by sleet and the freezing rain is the highest. The whole layer of snowfall and sleet temperature stratification is cold structure, and there is an inversion layer in freezing rain, presenting a “cold-warm-cold” distribution; 3) during snowfall, sleet and freezing rain, the specific humidity of Guiyang Airport is more than 3.5 g/kg and the divergence of water vapor flux is less than 0, indicating abundant water vapor. The vertical velocity is less than 0, and the ascending movement is significant. Water vapor flux divergence in lower layer (upper layer) is less than (greater than) 0, water vapor convergence rises (diverges).