Acoustic Pressure Signals Observed at 90 m and 130 m from the Return Strokes of Rocket-triggered Lightning

Inhalt:
Considering the few reports on the near-field acoustic pressure signals initiated from lightning return strokes focusing on the acoustic characteristics and the correlation with discharge parameters, in the summer of 2018 in Guangdong, China, an acoustic observation of rocket-triggered lightning was carried out. This study reports the waveforms of acoustic pressure signals initiated from 31 return strokes (RS) of 6 lightning flashes terminating on two rocket launchers, with a propagation distance of 90 m and 130 m to the measurement point. It was found that a typical near-field acoustic pressure waveform of the RS process consists of the first arrival N-shape wave, followed by the low-amplitude, lowfrequency, and oscillatory-attenuation acoustic waveform. All the observed acoustic waveforms could be classified into three types according to their waveform shape, which is found to be related to the occurrence of the M-component after the RS pulse. Quantitative analysis of the acoustic response corresponding to RS and the acoustic-electrical correlation was carried out based on the enriched acoustic-parameter definition. A significant linear relationship was found between the acoustic and electrical parameters related to current peak value and energy integral, with high statistical correlation coefficient R2. The propagation of acoustic waves from 90 m to 130 m was found to bring about 50% attenuation of amplitude. At the same time, it seems to have no significant impact on the parameters of rise time and duration of the acoustic waveforms.