一次特大暴雨过程三维和二维系统闪电特征对比分析

利用三维(ADTD-2C)和二维(ADTD)闪电定位系统资料, 对比分析了湖北省一次特大暴雨过程中两套系统闪电活动特征, 得出以下结论: (1)本次过程中地闪多于云闪, 二者均以负极性为主。(2)三维系统正地闪在地闪中的占比低于正云闪在云闪中的占比, 高于二维系统正地闪在地闪中的占比。(3)三维系统雷电流幅值集中分布在0~30 kA, 较二维系统(10~50 kA)更集中, 三维系统的雷电流累积概率较湖北省多年统计结果明显偏小, 二维系统的雷电流累积概率略高于统计值。(4)两套系统总地闪和负地闪活跃时段基本一致。(5)两套闪电定位系统地闪密集区基本一致, 且和云闪密集区基本重合, 闪电分布集中程度高, 主要分布在槽前正涡度平流区。三维系统地闪密度大于二维系统, 最大值分别为5.78 fl/(km2·d)和2.39 fl/(km2·d)。三维系统中正、负闪电交错分布, 二维系统中正、负地闪局部存在空间分离现象。(6)云闪密度大小与二维地闪相当、水平分布特征与三维地闪一致。垂直方向上, 云闪主要发生在10 km以下, 其中2~4 km云闪分布密集, 占总云闪的47.24%。 

COMPARATIVE ANALYSIS OF LIGHTNING CHARACTERISTICS OF A TORRENTIAL RAIN USING 3D AND 2D SYSTEMS

The present study uses the lightning data from three-dimensional (3D; ADTD-2C) and two-dimensional (2D; ADTD) lightning location systems to analyze the lightning characteristics of a torrential rain in Hubei Province. The results show that: (1) there is more cloud-to-ground lightning (CG) than intra-cloud lightning (IC) and both are mainly negative flashes. (2) The proportion of positive intra-cloud lightning (PIC) in IC is higher than that of positive cloud-to-ground lightning (PCG) in CG detected by the 3D system, which is higher than that detected by the 2D system. (3) The lightning current intensity detected by the 3D system has a smaller range (0~30 kA) than the one (10~50 kA) detected by the 2D system. (4) The active periods of negative CG and CG are basically the same. (5) The concentrated regions of IC and CG flashes have similar distributions on the positive vorticity regions. Lightning density of CG detected by the 3D system is higher than that detected by the 2D system, with the maximum values being 5.78 flashes/(km2·d)and 2.39 flashes/(km2·d), respectively. According to the 3D system, the positive and negative lightning are interlaced. By contrast, according to the 2D system, they have a spatial isolation distribution. (6) The density of cloud flashes is equivalent to that of CG detected by the 2D system, and its horizontal distribution characteristics are consistent with those of the CG detected by the 3D system. In the vertical direction, most IC occurs at the height below 10 km and mainly concentrates at the height between 2 to 4 km, accounting for 47.24% of the total IC.