一次冷涡降雹天气过程分析

An analysis of a cold vortex hail weather process

本文利用常规资料、地面加密资料、卫星资料、多普勒天气雷达资料、闪电定位资料和GFS资料(0.5°×0.5°,逐6小时),对2016年6月10日发生在河北省中北部的一次冷涡降雹天气过程进行了分析。结果表明:此次强对流天气受500hPa高空冷涡底部偏西气流控制,850hPa有切变并且伴有暖脊发展,上干冷下暖湿的环境场构成了有利环境背景,干冷空气入侵和边界层辐合线是对流的触发条件;40°N以北穿过河北省的500hPa上≥20m/s的急流核,是本次强对流天气发生的重要指标。从中小尺度特征看,冷涡云系位于河北西北部,前部有对流云带,云带东移南压造成东部地区强对流天气,并且局地对流发展旺盛,可见上冲云顶,高分辨率可见光云图上弧状云线和上冲云顶的识别和分析,有利于尽早判断对流云团的发展变化趋势;雷达回波呈带状分布,对流尾部不断有新生的对流生成;冰雹出现时正闪比例增加,正闪数量多于负闪,呈现出明显带状分布,与回波及冰雹落区对应,正闪频次的增加和空间分布对辨别冰雹的出现和落区具有明显的指示意义。

Based on the conventional data,ground encry pted data,satellite data,Doppler weather radar data,lightning loca-ion data and GFS data(0.5°×0.5°,6 h interval),a cold vortex hail weather process in the central and northern part of Hebei Province on June 10,2016 is analyzed in this paper.The results show that the strong convective weather was controlled by the westerly flow at the bottom of the cold vortex at 500 hPa,with the shear at 850 hPa and accompanied by the development of warm ridges.The upper dry cold and lower warm and wet environmental fields constituted the favorable environmental background,and the dry and cold air invasion and boundary layer convergence line triggered the convection;the jet stream core with speed greater than or equal to 20 m/s at 500 hPa passing through the north of 40°N of Hebei Province was an important indicator of the occur-rence of this severe convective weather.On the small and medium scale,the cold vortex cloud system was located in the north-west of Hebei Province,and there was a convective cloud belt in the front,which moved eastward and southward and caused strong convective weather in the east area,and the local convection developed vigorously with the upwelling cloud top.The identi-fication and analysis of arcus cloud line and upwelling cloud top on the high-resolution visible light cloud map was helpful in de-termining the development and change trend of convective cloud clusters as early as possible;the radar echoes was distributed in strip and new convection continuously generated at the bottom of convection;when hail appeared,the proportion of positive fla-flashes increased,and the number of positive flashes was more than that of negative flashes obviously distributed in strip.Cone-sponding to the echo and hail falling area,the increase and spatial distrihulion of positive flashes provide significant indication of the emergence and falling area of hail.