Preprints
https://doi.org/10.5194/nhess-2021-12
https://doi.org/10.5194/nhess-2021-12

  11 Feb 2021

11 Feb 2021

Review status: this preprint is currently under review for the journal NHESS.

Global ground strike point characteristics in negative downward lightning flashes – part 1: Observations

Dieter R. Poelman1, Wolfgang Schulz2, Stephane Pedeboy3, Dustin Hill4, Marcelo Saba5, Hugh Hunt6, Lukas Schwalt7, Christian Vergeiner7, Carlos Mata4, Carina Schumann6, and Tom Warner8 Dieter R. Poelman et al.
  • 1Royal Meteorological Institute, Brussels, Belgium
  • 2Austrian Lightning Detection and Information System (ALDIS), Vienna, Austria
  • 3Météorage, Pau, France
  • 4Scientific Lightning Solutions LLC (SLS), Titusville, Florida, USA
  • 5National Institute for Space Research, INPE, São José dos Campos, Brazil
  • 6The Johannesburg Lightning Research Laboratory, School of Electrical and Information Engineering, University of Witwatersrand Johannesburg, Johannesburg, South Africa
  • 7Institute of High Voltage Engineering and System Performance, Graz University of Technology, Graz, Austria
  • 8ZT Research, Rapid City, South Dakota, USA

Abstract. Lightning properties of a total of 1174 negative downward lightning flashes are analyzed. The high-speed video recordings are taken in different regions around the world, including Austria, Brazil, South Africa and USA, and are analyzed in terms of flash multiplicity, duration, interstroke intervals and ground strike point (GSP) properties. Although the results vary among the data sets, the analysis reveals that a third of the flashes are single-stroke events, while the overall mean number of strokes per flash equals 3.67. From the video imagery an average of 1.56 GSPs per flash is derived, with about 60 % of the multiple stroke flashes striking ground in more than one place. It follows that the channel creating a GSP is re-used by a factor of 2.3. Multiple-stroke flashes last on average 371 ms, whereas the geometric mean (GM) interstroke interval value preceding strokes producing a new GSP is about 18 % greater than the GM value preceding subsequent strokes following a pre-existing channel. In addition, a positive correlation between the duration and multiplicity of the flash is presented. The characteristics of the subset of flashes exhibiting multiple GSPs is further examined. It follows that strokes with stroke order of two create a new GSP in 60 % of the cases, while this percentage quickly drops for higher order strokes. Further, the possibility to form a new channel to ground in terms of the number of strokes that conditioned the previous channel shows that approximately 88 % developed after the occurrence of only one stroke. Investigating the time intervals in the other 12 % of the cases when two or more strokes re-used the previous channel showed that the average interstroke time interval preceding a new channel is found to be more than twice the time difference between strokes that follow the previous channel.

Dieter R. Poelman et al.

Status: open (until 25 Mar 2021)

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  • RC1: 'Comment on nhess-2021-12', Anonymous Referee #1, 01 Mar 2021 reply

Dieter R. Poelman et al.

Dieter R. Poelman et al.

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Short summary
Lightning properties of negative downward lightning flashes are analyzed. High-speed video recordings are taken in different regions around the world and analyzed in terms of flash multiplicity, duration, interstroke intervals and ground strike point properties.
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