Differences in M‐components between triggered lightning striking the ground and overhead line

Abstract

In the summer of 2018–2019, rocket‐triggered lightning experiments were conducted in Guangzhou, China. There were two types of lightning targets: ground and overhead line. By comparing the current and the electric field data in the two cases, it was found that when the continuous current level (ICC) and current amplitude (IM) of M‐components (current pulses generated during the continuous current stage) are large, the time difference between the electric field peak and the current peak (TD) will always be small. The rise time (RT) and half peak width (THPW) of M‐components with high ICC and IM are low in both the cases. The threshold upper limit of TD in the case of lightning striking the ground is higher, approximately 2.6 times than that in the case of lightning striking the overhead line. We use an optimised guided wave model to simulate the electric field waveforms of M‐components. It was found that the shorter RT and THPW of the M‐component, the smaller TD. The changes in wave speed and IM cannot affect the size of TD, and the impact of distance changes is very weak. The difference in the threshold upper limit of TD may be related to the significant difference in ground impedance in two cases.