对流风暴的移动和演变对下游地区对流降水影响的个例分析

利用加密自动气象观测站资料、多普勒天气雷达资料、葵花卫星资料及ERA5再分析资料,对2019年海上卫星发射气象保障过程中6月1日上游对流风暴的移动和演变造成山东半岛对流降水的机制进行了分析。结果表明:1)辐合线与干线重合触发新生对流单体形成潍坊风暴,潍坊风暴东移过程中强度增强和聊城风暴进入烟台后转向造成山东半岛一带出现对流降水。2)潍坊风暴在偏西气流引导下向偏东方向移动,沿着辐合线向着高温高湿的方向传播,强度增强。聊城风暴进入烟台后,在西西北气流的引导下转向东南方向移动,向着水汽辐合区传播,风暴水平尺度增长。3)聊城风暴进入烟台后传播方向与850 hPa风的方向相反,潍坊风暴发展阶段的传播方向与850 hPa风的反方向不同,二者之间有交角,850 hPa风速太小不足以影响风暴的传播运动。4)在重大活动气象保障过程中,短时临近监测非常重要。高分辨率卫星云图积云新生时间早于雷达观测到的新生单体的时间,可以提前发现对流初生和传播的先兆。多普勒天气雷达和加密自动气象观测站资料相互结合,可以综合判断对流风暴的平流和传播运动。对于本地动力强迫较弱或者处于天气系统边缘时,要考虑上游对流风暴的移动对下游地区的影响。

Case analysis of impact of motion and evolution of convective storm on downstream convective precipitation

Using the data of densified ground automatic weather stations (AWS), Doppler weather radar, Himawari-8, and ERA5 reanalysis, the mechanism of the convective precipitation as a result of the motion and evolution of the upstream convective storm on 1 June 2019 during the meteorological support for maritime satellite launching is analyzed. The results are listed as follows. 1) The coincidence of convergence line and dry line triggers the newborn convection cell and the Weifang storm is formed. The strengthening during the eastward moving of the Weifang storm and the turning of the Liaocheng storm after entering Yantai cause the convective precipitation in Shandong Peninsula. 2) The Weifang storm moves eastward under the guidance of the westerly flow, propagates in the direction of high temperature and humidity along the convergence line, and the intensity increases. After entering Yantai, the Liaocheng storm turns to go southeast under the guidance of the west-northwest steering flow, propagates toward the water vapor convergence zone, and its horizontal scale increases. 3) The propagation direction of the Liaocheng storm after entering Yantai is opposite to that of the wind at 850 hPa, yet the propagation direction of the Weifang storm during the development stage is different from the opposite direction of the wind at 850 hPa, as the wind speed at 850 hPa is too small to affect the propagation. 4) It is very important to conduct short-term monitoring in the meteorological support process for major events. The birth time of cumulus on the high-resolution satellite cloud imagery is earlier than that observed by the radar, which can discover the precursor of convective initiation and propagation in advance. The combination of the data of Doppler weather radar and densified automatic weather stations can comprehensively judge the advection and propagation of convective storm. It is necessary to consider the impact of the motion of upstream convective storm on downstream areas when the local dynamic forcing is weak or the area is on the edge of the weather system.