Investigating Lightning Characteristics through a Supercell Storm by Comprehensive Coordinated Observations over North China

Abstract

Electrical characteristics of an isolated supercell storm observed on 13 June 2014 over Beijing were investigated using lightning data obtained from the Beijing Lightning Network, radar reflectivity, and hydrometeor retrievals during the 6-h lifetime. Positive cloud-to-ground (+CG) lightning took a high percentage of CG lightning. Before and during a hail event, +CG lightning was more frequent than negative cloud-to-ground (-CG) lightning, except that +CG lightning took a high percentage at the beginning and in the dissipating stage. After the hail event ended, -CG lightning dominated and reached its maximum value. An analysis of hydrometeors retrieved by X-band polarimetric radar revealed that the discharge concentrated in the convective region with graupel particles and hailstones, whereas graupel, snow and ice crystals in the stratiform region. Lightning radiation sources were located mainly in the convective region, some of which were distributed along a gradient of radar reflectivity from the convective region to the stratiform region. The indication is that the supercell demonstrated an inverted tripole charge structure before the hail event, which converted to a normal tripole structure after the hail event.

摘要

基于北京闪电定位网所获得的闪电定位资料配合雷达以及粒子反演信息, 对 2014 年 6 月 13 日发生在北京地区的一次超级单体过程中的闪电活动特征和电荷结构分布进行了研究.

结果表明, 超级单体整个生命史中, 正地闪频数较高, 除了在初始阶段和消散阶段, 正地闪频数占地闪的比例较高之外, 降雹前和降雹期间, 正地闪比负地闪发生的更频繁. 降雹结束后, 负地闪频数占主导并达到了最大值.

利用双偏振多普勒天气雷达并结合反演的水成物粒子信息发现, 云内的放电主要集中分布在对流云区, 并且其主要的荷电水成物粒子为软雹和冰雹; 而在层状云区内, 带电粒子主要为软雹、 雪晶以及冰晶. 研究表明, 闪电辐射源主要集中分布在对流云区内, 一些辐射源在对流云区和层状云区之间的雷达反射率梯度大的区域内密集分布.

综合多种观测资料分析发现, 在降雹前, 超级单体呈现出反极性的电荷结构, 而在降雹后, 对流系统中电荷结构转变为常见的三极性电荷分布.