贵州一次热低压辐合线型冰雹天气过程分析

Analysis on Hail Weather Process of Primary Heat and Low Pressure Convergent Line in Guizhou

利用多普勒雷达资料和Micaps资料,对贵州2017年4月5日贵州冰雹天气过程进行分析,揭示强对流天气的环流形势和影响系统,以及各种有利于大冰雹生成的因素和回波特征。分析发现:该次降雹属典型的贵州热低压辐合线型(或高空槽型),降雹区位于地面辐合线南侧,冰雹直径在10 mm以上的站数占总站数的61%,最大直径为20 mm;CAPE、SSI、K、Si指数和垂直风切变等大气对流参数很好地预示此次强对流天气的发生。本次过程具备适宜冰雹生长的0℃和?20℃层高度的条件,两层之间厚度3 km;这次雹暴具有强烈对流风暴的回波特征:反射率因子图上的弓形回波、悬垂结构、有界弱回波区、三体散射和中层径向辐合。贵阳回波定高为31.5 kft,强回波区高度扩展到?20℃层以上,垂直液态水含量最大值为8.03 kg/m2;5日EC模式给出了较好的预报结果,但是对于地面风场的预报明显低于实况,特别是安顺至贵阳北部的南风,模式预报6~8 m/s,实况13时持续增强到8~12 m/s,因此模式预报强降水落区比实际偏南,实际应用时需要根据地面实际风场分析辐合线位置及辐合强度,对落区进行订正。

Using Doppler radar data and Micaps data, this paper analyzed the hail weather process in Guizhou on April 5, 2017, and revealed the circulation situation and influence system of severe convective weather, as well as various factors conducive to the generation of large hail and echo characteristics. It was found that the hail was a typical low-pressure convergence line (or high-slot type) of Guizhou heat, and the hail area was located in the south of the convergence line of the ground. The number of stations with a diameter of 10 mm or more accounted for 61% of the total stations, and the maximum diameter was 20 mm. Atmospheric convection parameters such as CAPE, SSI, K, Si index and vertical wind shear predicted the occurrence of severe convection weather. In this process, the height of 0?C and ?20?C layers suitable for hail growth was obtained, and the thickness between the two layers was 3 km. This hailstorm has the echo characteristics of strong convective storm: bow echo, drapery structure, bounded weak echo region, Trisolarum scattering and intermediate radial convergence on the reflectivity factor diagram. The height of Guiyang echo was set at 31.5 kft, and the height of the strong echo zone expanded above the ?20?C layer. The maximum value of vertical liquid water content was 8.03 kg/m2. 5 EC model gives better prediction results, but for actual forecast is significantly lower than the ground wind field, especially in the north of Anshun to Guiyang south, model forecast 6~8 m/s, when live 13 continues to increase to 8 to 12 m/s, so the model forecast heavy rainfall area south, than the actual need ac-cording to the actual surface wind field analysis in actual applications convergence line position and intensity of convergence, the correction was carried out on the drop zone.