Evolution Characteristics During Initial Stage of Triggered Lightning Based on Directly Measured Current

Atmosphere

Yijun Zhang¹  Dong Zheng²  Zefang Chen²  Yang Zhang²  Xiangpeng Fan²  Liangtao Xu²  Jingxuan Wang²  Yanfeng Fan²  Weitao Lyu² 

[1] Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China;State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China;

关键词: triggered lightning;    initial discharge;    evolution characteristics;    directly measured current;   

DOI  :  10.3390/atmos11060658

来源: DOAJ

【 摘 要 】

The initiation of a leader is an important lightning discharge process, but how an upward positive leader (UPL) initiates is still not fully understood. The evolution characteristics of a UPL during its initial stage was systematically studied based on directly measured current data of 14 triggered lightning events in 2019. It was found that the initial stage of triggered lightning can be divided into two types: a single initial process form and a multiple initial process form, with percentages of 64.29% and 35.71%, respectively. Compared with the former, the latter usually lasts longer, and the corresponding lightning is often triggered under a lower ground-level quasi-static electric field. In each initial process, precursor current pulses (PCPs), PCP clusters and initial precursor current pulse (IPCPs) are typical current waveforms, and the pulse durations and transferred charges of PCPs increase linearly with time. However, in the multiple initial process form, the pulse durations and transferred charges of PCPs will reduce significantly after each previous initial process and then continue to increase in the following initial process. In each initial process, when the pulse duration and transferred charge of a PCP increase to a certain extent, PCP clusters and IPCPs begin to appear. For the emergence of PCP clusters, the average values of the threshold are 3.48 μs and 19.53 μC, respectively. For the occurrence of IPCPs, the corresponding values are 4.69 μs and 27.23 μC, respectively. The average values of pulse durations and transferred charges of IPCPs are larger than those of PCP clusters. Compared with adjacent PCP clusters, IPCPs contain more pulses, with a critical range of 6–7. IPCPs also last longer, and have a critical range of 138–198 μs.

【 授权许可】

Unknown