云南红河一次春季超级单体风暴强对流天气特征分析

ANALYSIS OF CONVECTIVE WEATHER CASE CHARACTERISTICS OF A SPRING SUPER CELL STORM IN HONGHE PREFECTURE YUNNAN PROVINCE

利用地面气象观测资料、高空大气探测资料和物理量场、风云卫星云图等,对2020年3月24~25日云南红河发生的一次超级单独风暴强对流天气过程进行了研究,并利用C波段天气雷达探测资料对风暴云团的结构和对流风暴的发展过程进行了详细分析。研究发现,此次超级单体风暴天气过程是南支槽东移过程中,高层冷平流叠加在低层暖湿气流之上形成冷平流强迫,在地面辐合线附近受到哀牢山的地形抬升作用触发形成的。在风暴发展阶段,中高层以上升气流为主,低层有下沉气流,雷达反射率因子上指状回波和三体散射特征明显,有冰雹和短时强降雨产生;在风暴成熟阶段,下沉气流在风暴移动方向的前方,上升气流在风暴移动方向的后方,上升气流与下沉气流共存,中低层辐合高层辐散的结构特征十分明显;风向风速存在剧烈切变,雷达反射率因子上“钩”状回波结构特征明显并伴有回波悬垂和有界弱回波区,径向速度图上有与之对应的正负速度对,风暴云团后侧有“V”型槽口,地面出现了直径50 mm大冰雹和雷暴大风;在风暴减弱阶段,单体风暴以下沉气流为主,反射率因子最大值降低、强回波核面积缩小。

We analyzed a severe convective weather process from March 24-25,2020 in Honghe prefecture by ground meteorological observation data,aerial atmosphere detection data and physical measuring field,Fengyun satellite cloud map,etc,and also analyzed the structure and development process of the storm cloud by the detection data of C band weather radar.The study found that the super cell storm weather process was formed during the eastward shift of the south branch,the upper-rise cold flat superimposed on the low layer warm and wet air flow to form a cold flat force,and triggered by the topographic uplift of Ailao Mountain near the ground convergence line.During the development stage of the storm,the middle and upper levels are dominated by upper airflow,and the lower layers have sinking airflow.Significant finger-echo and three-body scattering characteristics were observed in radar reflectance,with hail and short-term heavy rainfall.In the mature stage of the storm,the sink flow is in front of the moving direction of the storm,the rise flow is behind the moving direction of the storm,the rise flow and the sink coexist,the structure characteristics of middle-level convergence and upper-level divergence is very obvious,and the wind direction and wind speed have sharp shear,the“hook”echo structure on the radar reflectance factor is obvious and accompanied by echo hanging and bounded weak echo area,with corresponding positive and negative velocity pairs on the radial velocity diagram,and“V”groove on the back of the storm cloud,large 50mm-diameter hail and thunderstorm winds hit on the ground.During the weakening stage,the single storm is mainly sinking airflow,with the maximum reflectivity factor decreasing and the strong echo core area decreasing.