Properties of unipolar magnetic field pulse trains generated by lightning discharges

Ivana Kolma Sová (1) , Ondřej Santolík (2)

1 IAP - Institute of Atmospheric Physics [Prague]
2 Faculty of Mathematics and Physics [Praha/Prague]

We analyze and describe trains of regular unipolar microsecond-scale magnetic field pulses produced by intracloud lightning discharges. Waveforms of the magnetic field are measured using a newly developed broadband analyzer with a sampling interval of 12.5 ns. The observed trains contained several tens of pulses, and the time interval between neighboring pulses typically varied between 1 and 10 ms. The amplitude of the pulses also varied by 1 order of magnitude. A systematic analysis of these variations is done for the first time. The interpulse interval is usually increasing (on average by 4.1 ms during a train), and the pulse amplitude is decreasing (on average by 15% of the maximum value within a given train). We propose a possible generation mechanism based on a hypothesis that periodical charge structures are present in the thundercloud. This mechanism can explain the observed evolution of peak amplitudes and interpulse intervals.

Mots clés: train of pulses; dart-stepped leader; K change

Domaines: Géophysique [physics.geo-ph]; Physique Atmosphérique et Océanique [physics.ao-ph]

Ivana Kolma Sová, Ondřej Santolík. Properties of unipolar magnetic field pulse trains generated by lightning discharges. Geophysical Research Letters, 2013, 40 (8), pp.1637 - 1641. ⟨10.1002/grl.50366⟩. ⟨insu-01396166⟩