2015年7月29日华北一次短时强降水的闪电活动特征

Lightning Activity Characteristics of a Short-Time Heavy Rainfall in North China on July 29, 2015

摘要: 本文利用ADTD、WWLLN闪电定位资料、S波段天气雷达、地面降水观测资料和ERA5再分析资料，针对2015年7月29日华北一次极端短时强降水过程开展精细化个例研究，分析强降水系统的闪电活动时空演变。对强降水–强闪电和强降水–弱闪电雷暴系统进行对比，初步探讨了特定电活动背景下极端降水形成机制的可能差异。结果表明：在此次特定天气事件中，南部强闪电系统闪电与强回波同步发展，最大反射率达70 dB，40 dB强回波顶高稳定在18.5~19.5 km，强回波质心进入−10℃至−20℃混合相态起电层，强上升气流支撑冰相粒子有效碰并，闪电密度峰值达7.8次/100 km²/6 min；北部弱闪电系统虽然降水范围广、回波强，但呈现对流区后置、层状云区前置的结构，单体合并后大粒径水凝物快速下落抑制了上升气流，且冰晶被输送至前方层状云区，与后方对流区的霰粒子发生空间分离，导致混合相态区有效碰并概率大幅降低，非感应起电难以维持，最终表现出强降水–弱闪电特征。

Abstract: In this paper, ADTD, WWLLN lightning location data, S-band weather radar, surface precipitation observation data and ERA5 reanalysis data were used to carry out a detailed case study on an extreme short-term heavy rainfall process in North China on July 29, 2015, and to analyze the temporal and spatial evolution of lightning activity in the heavy rainfall system. By comparing the strong precipitation-strong lightning and strong precipitation-weak lightning thunderstorm systems, the possible differences in the formation mechanism of extreme precipitation under the background of specific electrical activity are preliminarily discussed. The results show that in this specific weather event, the lightning and strong echo of the southern strong lightning system developed synchronously, the maximum reflectivity reached 70 dB, the top height of 40 dB strong echo was stable at 18.5~19.5 km, the center of mass of strong echo entered the mixed phase state electrification layer from −10˚C to −20˚C, the strong updraft supported the effective collision of ice particles, and the peak value of lightning density reached 7.8 times/100 km²/6 min. Although the weak lightning system in the north has a wide range of precipitation and strong echo, it presents a structure of rear convection area and front stratiform cloud area. After the merging of the cells, the rapid fall of large-size hydrometeors inhibits the updraft, and the ice crystals are transported to the front stratiform cloud area, which is spatially separated from the graupel particles in the rear convection area, resulting in a significant reduction in the effective collision probability of the mixed phase region, and the non-inductive electrification is difficult to maintain, and finally shows the characteristics of strong precipitation-weak lightning.