云闪反冲流光过程的电磁场计算及其影响因素分析

Calculation and its affecting factors of intracloud lightning electromagnetic field during the recoil streamer process

针对云闪反冲流光的电磁辐射问题,基于偶极子法建立了云闪反冲流光过程的三维电磁场计算模型,研究获得了观测方位角、反冲流光传播速度以及通道弯曲对其地面电磁场计算的影响规律.结果表明:除中间过渡场区以内的地面电场外,观测方位角越大,斜向云闪通道地面电磁场的幅值越小;反冲流光传播速度越大,相应地面电磁场的幅值越大、脉冲宽度越窄;云闪通道弯曲将导致地面电磁场波形出现不同程度的起伏波动,但沿斜向通道主干附近出现的随机弯曲,基本不会影响其地面电磁场波形的整体走势.

Aiming at the issue of electromagnetic radiation from the recoil streamer of intracloud light- ning discharge, a three-dimensional model for lightning electromagnetic field calculation during the recoil streamer process is presented based on the dipole method. Effects of the observation azimuth angle, recoil streamer propagation speed, and tortuosity of channel on lightning electromagnetic field are analyzed. The results show that with the exception of on-ground electric field within the intermediate zone, the bigger the observation azimuth angle is, the smaller the on-ground electromagnetic field of the oblique channel will be. The larger the propagation speed of recoil streamer, the bigger the on-ground electromagnetic field and the narrower the pulse-width of them. The tortuosity of lightning channel can result in some fluctuation in the lightning electromagnetic field waveform. However, for the channel with random tortuosity along an oblique channel, the main trend of its on-ground electromagnetic field waveforms are basically consistent with that of the oblique channel.