| 17 Dec 2024
Characterisation and modelling of lightning strikes as point events in time and space
Abstract. Lightning is a spatio-temporal phenomenon comprised of individual strikes with specific occurrence times and spatial coordinates. This study models and characterises lightning strikes from single thunderstorms, treating each strike as a point event. Utilising real-world datasets, we characterise and model lightning strikes’ physical properties. Our analysis involves two severe UK thunderstorm systems selected based on published synoptic analyses. These systems enable subdivision of the lightning dataset into subsets, each representing a distinct thunderstorm. Our two major storm systems feature three thunderstorms each: Storm system A with 7955, 11988, and 5655 strikes over the English Midlands on 28 June 2012; Storm system B with 4218, 455, and 1926 strikes characterised over northern England on 1–2 July 2015. These six datasets exemplify individual thunderstorms with three physical attributes: movement speed, lightning inter-event time distribution, and spatial spread about the storm track. Applying least-squares plane and linear fits in the spatio-temporal and lag spaces, we estimate movement speeds of 47–59 km/h and 67–111 km/h for Storm systems A and B, respectively. The inter-event time distribution ranges from 0.01 to 100 seconds, with density peaks around 0.1 seconds and at 1–10 seconds. Autocorrelation analysis in natural time reveals significant autocorrelation in all storms, varying from short-range to long-range. For spatial spread, calculated as the distance from the storm track to the strikes, we employ a linear filter to establish the storm track. This analysis yields typical spatial spreads up to 80 km in either northing or easting dimensions, with an outlier of 226 km in the northing dimension for one storm. The paper concludes with a synthetic lightning strike model. This model allows the selection of each storm’s starting points, directions, and movement speeds, generating point events based on our characterisation findings. This comprehensive study of lightning strikes in time and space accurately reflects severe thunderstorms’ behaviour and informs statistical models for simulating lightning events.
Competing interests: Bruce Malamud is on the editorial board of NHESS. Bruce Malamud has co-authored with one of the suggested reviewers (Mario Gonzalez Pereira) in 2011.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
Review of “Characterisation and modelling of lightning strikes as point events in time and space” by Zandovskis et al.
General comments
I have read through this paper and whilst it has some merits, I believe it needs a thorough re-write to be of a reasonable length and accessible to the reviewers and readers. There is so much content presented here that it is very hard to work out what is appropriate and relevant to the investigation and what is just additional material, which could be removed. I have tried to do my best in the remainder of my review, but I feel like it would be best if the authors revise the size of the manuscript down and then resubmit it so I can look through it again and advise on its merits. The paper can really be thought of as two separate halves. The first half is largely unnecessary in my opinion: it is mostly just plotting and re-plotting the lightning data which has been obtained from the Met Office and to me doesn’t add much value to what has already been documented (e.g. by Clark and Webb, 2013 or by Lewis and Silkstone, 2017). Yes, there is some re-clustering here, but it is largely the same data plotted multiple times. The second half of the paper (from section 4 onwards) appears very novel and is what the authors should emphasise in their revised manuscript (and what the reader would be interested in looking through). I do wish the authors all the best with this manuscript and hope to see a revised version in due course.
Major Comments
a. The same lightning strikes are plotting in three dimensions (northing, easting, time) in figures 2, 3, 4 and 5. You should consider if all these figures are appropriate and if it would be possible to display the same data on just one or two figures.
b. The data presented in figure 8 is the plotted again in figure B2 with different projections. This suggests that the method used to plot the data isn’t that good. Could you instead use 2D subplots (e.g. northing vs time, easting vs time, northing vs easting) instead of a 3D one? This would make the data clearer to visualise.
c. I’m also not sure what the plots in figures 7 and 10 add to the paper (especially in figure 10 where there’s not much spread in the Easting direction).
d. What additional information does Table 2 provide that can’t already be judged from the lightning maps provided?
Minor Comments