Distribution of cloud-to-ground lightning electromagnetic pulse fields under the ground
地闪雷电电磁脉冲在大地中的分布研究

In order to find out the distribution of lightning electromagnetic pulse (LEMP) fields under the ground, the two-dimensional finite-difference time-domain method is used to calculate LEMP under the ground. The distributions of LEMP under the ground are calculated in the cases of different distances from the lightning channel, different ground conductivities, different ground permittivities and different depths. The attenuations of lightning fields in the ground are compared with those of other high-power electromagnetic environments. The calculated results show the following points: the LEMP dramatically attenuates as the distance increases; the attenuation of the electric component is significant when the ground conductivity is reasonably high; the change of ground permittivity mainly causes the change of vertical electric field component, which decreases as the ground permittivity increases; the attenuation of the high frequency electric component increases and that of the low frequency electric component invisibly changes as the depth increases.