the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 12 Feb 2024
Thunderstorm characteristics with lightning jumps and dives in satellite-based nowcasting
Abstract. The first Meteosat Third Generation (MTG) satellite was launched in December 2022. Its high resolution Flexible Combined Imager (FCI) in combination with the Lightning Imager (LI) herald a new period for geostationary (GEO) weather observations over Europe, Africa, and adjacent regions. Similar instruments are already operational over the U.S., with the Advanced Baseline Imagers (ABIs) and the Geostationary Lightning Mappers (GLMs). The objective of this study is to gain a deeper understanding of GEO data, with a specific emphasis on sudden increases in a storm's lightning activity, referred to as lightning jumps (LJ), and decreases, known as lightning dives (LD), as observed from a geostationary orbit. ABI-based cloud characteristics of thunderstorms are analyzed while storms are categorized by whether they produced LJs, LDs, or severe weather. It is found that the storms with LJs and/or LDs feature overall similar characteristics as the severe thunderstorms. Those storms typically feature elevated, colder cloud tops, more and stronger overshooting tops (OTs), consequently leading to more structured updrafts. As a result, these storms tend to generate higher convective rain rates (CRRs) on average compared to storms lacking LJs, LDs, and those categorized as non-severe. In particular, thunderstorms experiencing multiple LJs throughout their lifecycle exhibit the most and strongest OTs, signifying highly organized updrafts, extremely cold cloud tops, and highest CRRs. Considering the characteristics mentioned above, these storms, especially those featuring multiple LJs and LDs during their lifecycle, are of particular interest for nowcasting potentially dangerous weather phenomena.
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RC1: 'Comment on egusphere-2024-174', Anonymous Referee #1, 13 Mar 2024
I have read this paper on lightning jumps and dives for the use in nowcasting, and while the topic is interesting, I think the paper needs major revisions before it can be considered for publications.
Major comments:
1) The paper is much too long. It appears to be a follow on of a previous paper by the authors that shows similar results. The paper appears to be a shopping list that brings basically all parameters possible to compare with lightning jumps and dives, without the focus needed and defined by the title of the paper. This is very distracting for the reader since there is too much information provided without a clear storyline. If you want to use lightning for nowcasting of severe weather or floods, you should focus on that. It is clear to all (nothing new) that storms with LJs with be more developed with stronger updrafts, higher tops, colder tops, more overshooting turrets, etc. This is not new, and hence does not contribute to our scientific knowledge. Just presenting these results again does not make them novel or innovative. So I would focus ONLY on the use of LJ for severe events. Remove all the analysis not related to severe weather and LJs
2) This brings me to the next point that as the authors point out in lines 176-177, 60% of storms with LJs do not produce severe weather, and there are severe weather events without LJs in 57% of cases. So this shows that lightning jumps from the GLM are NOT good for predicting and nowcasting of severe weather. So why continue with the paper then. Either the paper is not about nowcasting, and then you need to change the title and focus of the paper, or you need to prove that LJs are good in predicting severe weather. Here I would separate the analysis for tornadoes, wind damage, and hail. And if LJs are not good for detecting severe weather from GLM, then that too is a result, even if "negative". But no need to go on and on about cloud parameters linked to thunderstorms with LJs.
3) I do not understand the interest in lightning dives (LDs). This is the first time I hear of their "importance" as a measure of thunderstorm activity. The physical meaning of LJs is the intensification of the storms, with stronger electrification, more rainfall, and maybe more severe weather. But why should we be interested in LDs which imply the decay of the updrafts in the storm, the drop in electrification, the drop in lightning, and hence the drop in probability of severe weather. Why should LDs be important for severe weather. Please explain the physical connection if you plan to keep talking about it. I would focus only on the LJs and remove the LDs analysis.
Minor comments:
Title: The paper does not focus on nowcasting. Either it should, or the title should be changed.
line 19: ...certain maxima and minima
line 23: do you have a reference for "lightning dives" other than your own papers? Please add reference
line 93: study aims
line 124: Problem with text after 777.4nm
line 152: Both algorithm types use a FR
line 172: do not produce
line 174: It is obvious that what goes up must come down. Hence all LJs with be followed by a LD. Is this not a trivial conclusion
line 179: would still show
line 196: Again, it is obvious that min pressure implies higher cloud tops and min BTs
Figure 2 appears to be a shopping list with no clear point. Are the overlapping blue boxes in 2a significantly different from each other?
Line 217 and 236: Reference to Fig 2a should occur before Fig. 2b
Line 330: Are these conclusions new? It appears a logical conclusion of more lightning in thunderstorms that has been studied for decades.
line 334: "severe storms often feature".....quantify this. How often? This qualitative conclusion is not scientific
line 340: "might cause flash floods" is speculation. Do you not have information of floods at the surface? If not you cannot speculate so broadly.
line 341: If the results here are similar to your previous publication, why do we need another publication saying the same thing? You need to provide new knowledge to advance the sciences and field of thunderstorm research and nowcasting.
line 347: 2.1 +- what standard deviation? Same for 1.9. Are these values statistically different?
line 353: tropopause
Line 396: I would like to see more spatial plots in the paper like A1. Maybe a plot showing lightning jumps compared with severe weather reports of different kinds. I would add spatial plots to the main text
Citation: https://doi.org/10.5194/egusphere-2024-174-RC1 - AC2: 'Reply on RC1', Felix Erdmann, 23 Apr 2024
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RC2: 'Comment on egusphere-2024-174', Anonymous Referee #2, 25 Mar 2024
Title: Thunderstorm characteristics with lightning jumps and dives in satellite-based nowcasting
Author(s): Felix Erdmann and Dieter Roel Poelman
MS No.: egusphere-2024-174
MS type: Research article
Thunderstorm characteristics with lightning jumps and dives in satellite-based nowcasting" by Felix Erdmann and Dieter R. Poelman presents an attempt of adapting the Lightning Jump to satellite imagery (Lightning Imager), as also introduces a new concept, such as the Lightning Dive. The results are interesting and promissing, having in mind the put in operation of the MTG in an early future. The main issue the lack of information regarding this last concept, because it is a novelty and it should be better introduced, with some examples that should help to make more understandeable to the reader. Besides, there is some vaguety about the "severe weather" convept, which it must be better explained. Finally, the results are sometimes presented in a difuse way and I think the Authors could do an effort to improve the quality of presentation.
You can find below the specific comments associated with the review.
L21: "The opposite behavior, a sudden decrease in the FR is termed a lightning dive (LD)" Referència?
Introduction: "Severe" or "Adverse" weather?
Have you noticed if "However, most LJ algorithms were tuned based on ground-based lightning mapping array (LMA) data." are operational and running in real-time? (L44)
L80: "The object-oriented approach can effectively differentiate between convective and non-convective cloud cells, and track the convective cells through image recognition, identification of known patterns, and statistical models." Have you any feed-back comparing with weather radar database?
L104: why these thresholds?
Caption: "Figure 1. Relations between tools and data of this study." Is this a data flow? If yes, please change the caption.
L 90: "During our selected study days (Table 1), there was one important GOES-16 downtime from 03 Jun 17:00UTC to 04 June 01:30UTC." change to "It is worth noting that there was one relevant GOES-16 downtime from 03 Jun 17:00UTC to 04 June 01:30UTC (Table 1)."
L92: "It should be noted that only thunderstorms are analyzed that are defined as RDT cloud cells with GLM lightning activity." This sentence is difficult to understand.
L93: "This studies aims at understanding the meaning of LJs and LDs for thunderstorm characteristics." -> "This study aims to understand the meaning of LJs and LDs for thunderstorm characteristics."
L95: "Such cells generally give rise to weaker weather phenomena compared to major thunderstorms." Partially disagree: warm rain clouds cause heavy rainfall and flash floods in many regions around the World.
Section 2.3: Have you considered the parallax effect? Besides, which is the general size of a RDT cell? Have you manually evaluated these thresholds in any case, to validate them?
L120: Have you evaluated the limitation of using standard scan instead of rapid scan? Which is the time running of the NWCSAF software?
L160: I think you should present an example of the LD, because is not an usual phenomenon as LJ and it needs to be assimilated by the reader.
Section 3.1: the thunderstorm' categorization should be presented as part of the methodology. The analysis of the categories should be included in the Results section.
L172: Why do you think there are more LD than LJ?
L173: "A thunderstorm can produce more than one type of severe weather (the sum of withTornado, withHail, and withWind is greater than the number of severe TSs)." Please, write more clearly.
L174: This sentence is reduntant and can be shortened
L176: "There are storms with LJs and/or LDs that did not produce severe weather (59.9 % and 71.9 %, respectively)." Disagree. Severe storm can occurr but it has not been reported (or reported to the used database)
L319 Rigo and Farnell (2022) did not analyze LMA-based multi-LJ storms
Citation: https://doi.org/10.5194/egusphere-2024-174-RC2 - AC1: 'Reply on RC2', Felix Erdmann, 23 Apr 2024
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