Characterizing Pulse Attenuation of Intra-Cloud and Cloud-to-Ground Lightning with E-Field Signal Measured at Multiple Stations

In this paper, we analyze the waveform data of nearly 200,000 intra-cloud (IC) and cloud-to-ground (CG) lightning discharges detected by the Jianghuai Area Sferic Array on 26-29 August 2019 to investigate the propagation features of lightning electromagnetic fields. Through the analysis of variation in the electric field (E-field) signal of lightning during the actual propagation, it was found that (1) the attenuation of lightning E-field signal with distance can be fairly well described by the power-law relationship E = ar(-b), and the attenuation index is b = 1.02 (for IC) and b = 1.13 (for CG); (2) under the situation of the same propagation path, the IC pulses experience less attenuation than CG pulses; and (3) through the comparison with simulations, it can be seen that the attenuation of lightning E-field pulse is affected by the conductivity of the ground surface, and according to the attenuation factor of lightning E-field strength, it can be inferred that the conductivity in the Jianghuai area ranges between 0.005 S/m and 0.01 S/m, which is in good agreement with the measured conductivity in this area. Our results suggest that lightning radiation could provide a feasible means for remotely sensing the ground conductivity.