EGU22-3752, updated on 27 Mar 2022
https://doi.org/10.5194/egusphere-egu22-3752
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Characteristics of pulse trains observed during the initial stage of high peak current winter flashes

Ivana Kolmašová1,2, Ondřej Santolík1,2, Stéphane Pedeboy3, Andrea Kolínská2,1, Samuel Amrich2,1, Radek Lán1, and Luděk Uhlíř1
Ivana Kolmašová et al.
  • 1Department of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czechia (iko@ufa.cas.cz)
  • 2Faculty of Mathematics of Physics, Charles University, Prague, Czechia
  • 3Météorage, Pau, France

Our study aims at initial stage of energetic negative cloud-to-ground (CG) winter lightning flashes. We analyze broadband magnetic-field measurements recorded in the West Mediterranean region in winter 2014/2015. By combining our data with information provided by the French national lightning locating system MÉTÉORAGE, we were able to select 200 waveform captures, which contained return stroke (RS) pulses emitted by negative CG discharges with peak currents exceeding 100 kA. The frequency band of our instrumentation (5 kHz-90 MHz) allowed us to investigate fine details of recorded waveforms. We found that the winter pre-stroke processes were very short, lasting on average only 1.7 ms from the first bipolar preliminary breakdown (PB) pulse to the following return stroke pulse.  The amplitudes of the strongest PB pulses reached on average only 25 % of the corresponding RS pulse. We investigate the evolution of peak amplitudes and inter-pulse intervals of PB pulses within individual PB trains. We found that in some trains the amplitudes of pulses were nearly monotonically increasing with time, they reached a maximum in a few hundreds of microseconds, and then decreased again being relatively regularly distributed in time. Within other PB trains, the pulses were chaotically spaced and their peak amplitudes did not show any trend. We assume that the short duration of the pre-stroke process indicate strong electric fields inside winter thunderclouds and hypothesize that the time evolution of PB pulse amplitudes and interpulse intervals reflect the spatial arrangement of the negative charge region.

How to cite: Kolmašová, I., Santolík, O., Pedeboy, S., Kolínská, A., Amrich, S., Lán, R., and Uhlíř, L.: Characteristics of pulse trains observed during the initial stage of high peak current winter flashes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3752, https://doi.org/10.5194/egusphere-egu22-3752, 2022.

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