Transient Luminous Events in the Lower Part of the Atmosphere Originated in the Peripheral Regions of a Thunderstorm
, Gagik Hovsepyan 1, Tigran Karapetyan 1, Balabek Sargsyan 1 and Ekaterina Svechnikova 2Round 1
Reviewer 1 Report
General comment
The paper is devoted to complex and multichannel measurements of energetic processes in Aragats region using charged particles detectors and all-sky video cameras. This work is a continuation of previous studies made by Erevan Physical Institute scientific group. It is a new interesting work with new data. But there are some points that should be clarified before publication.
Specific comments
Line 53: What is meant by “real flash”. Does it a returns stroke of lightning? It is better to specify.
In the paper a RREA mechanism is mentioned as the only one that can explain high energy electrons and gamma rays. Why other possibilities are not discussed? The electric field seems to be so high that it exceeds the usual breakdown mechanism, not only RREA. Also extensive air shower electrons may be accelerated additionally and produce higher flux than during good weather.
Figure 2 may be omitted since it doesn’t have any useful information for the paper.
The paragraph with STAND1 measurements principles (page 3) is confusing. What is it “efficiency of scintillator”? (Charge particles registration efficiency?). How it can measure gamma if the efficiency for electrons is 2 orders of magnitude higher? How gamma can be separated from electrons. Also, what energies of gamma and electrons are measured?
Page 4. What means “IC positive and negative lightning types”? For cloud-to-ground it determines the direction of current (to ground or to cloud). For IC it is always between clouds…
Line 165: WEB calculators – what it is?
Line 177: “Maximum of the differential spectrum” – what does it mean? Differential spectrum of electrons during maximum of their flux or anything else?
In line 176 it is said that peaks in electric field corresponds to maximum flux of TGE. But in fig.4 we don’t see 3 peaks in STAND1 charge particles measurements. Interesting to understand why.
Figure 7. What is the meaning of linear fit. It seems that spectrum consists of different parts. Is it correct to make one fit for the whole energy range? Moreover it is not discussed in the text.
Figure 9 is a wonderful picture of Aragats station, but does not add to much to the paper, I think it may be omitted.
The last sentence in 12 page. Was it simulated to estimate sensitivity of different stations (MAST, MAKET) located at different heights?
In the discussion there is statement about new luminous phenomena under clouds observed together with electric field disturbances. How accurate the altitude estimation is done not obvious. In line 279 it is written that lights are 100 m height while cloud – 90 m which contradicts the conclusion. If it is blue jet or starter it will not terminate charge particle flux as well. These phenomena are not related to parent lightning and may occur in the periphery of a thunderstorm. So, the conclusion about new phenomena seems not to be very reliable. And other possibilities should be discussed and rid out.
Technical corrections
line 27: are à as
line 27: “-“ should be deleted
line 41 and though out of the text: FoW – FoV (since it is fielf of View)
line 58: Using à using
line 72: Fig. 2a à Fig. 1a
line 74: HZ à Hz.
line 79: WWLN à WWLLN
line 85: 1-m2 à 1 m2 and the same correction through out of the text.
Numeration of parts! Always 1.
Author Response
Comments and Suggestions for Authors
General comment
The paper is devoted to complex and multichannel measurements of energetic processes in Aragats region using charged particles detectors and all-sky video cameras. This work is a continuation of previous studies made by Erevan Physical Institute scientific group. It is a new interesting work with new data. But there are some points that should be clarified before publication.
Specific comments
Line 53: What is meant by “real flash”. Does it a returns stroke of lightning? It is better to specify.
The sentence is deleted from the introduction section to avoid misunderstanding. We discuss the possible origin of the light glows observed on Aragats in the discussion section of the manuscript (MS)
In the paper a RREA mechanism is mentioned as the only one that can explain high energy electrons and gamma rays. Why other possibilities are not discussed? The electric field seems to be so high that it exceeds the usual breakdown mechanism, not only RREA. Also extensive air shower electrons may be accelerated additionally and produce higher flux than during good weather.
Clarifications and additional references are added, denoted by red in corrected version of MS.
Figure 2 may be omitted since it doesn’t have any useful information for the paper.
Agree, a smaller version of Fig.2 is added to a new Figure requested by the second referee.
The paragraph with STAND1 measurements principles (page 3) is confusing. What is it “efficiency of scintillator”? (Charge particles registration efficiency?). How it can measure gamma if the efficiency for electrons is 2 orders of magnitude higher? How gamma can be separated from electrons. Also, what energies of gamma and electrons are measured?
Explanations, energy thresholds, and references added
Page 4. What means “IC positive and negative lightning types”? For cloud-to-ground, it determines the direction of current (to ground or to cloud). For IC it is always between clouds…
Explanation added.
Line 165: WEB calculators – what it is?
Web-based programs for estimation of the cloud base, explained, reference added
Line 177: “Maximum of the differential spectrum” – what does it mean? Differential spectrum of electrons during maximum of their flux or anything else?
The maximum value of the differential energy spectrum was measured by the NaI spectrometers for each minute of TGE, see Fig 7. Explanations added to MS.
In line 176 it is said that peaks in electric field corresponds to maximum flux of TGE. But in fig.4 we don’t see 3 peaks in STAND1 charge particles measurements. Interesting to understand why.
In Fig 4 we see a broad maximum during 3 minutes (19:19-19:23), which corresponds to the outbursts and light glows time. We do not resolve each outburst relative to particle flux, but, as it is seen in Fig. 7 the maximum energies of diff. energy spectra could be related to the outbursts each minute.
Figure 7. What is the meaning of linear fit. It seems that spectrum consists of different parts. Is it correct to make one fit for the whole energy range? Moreover it is not discussed in the text.
Agree, the low-energy part of spectra shown in Fig 7 is a mixture of TGE and Rn progeny gamma radiation. We measure Rn progeny radiation with a precise spectrometer of ORTEC firm; results were published in several papers. The present paper is devoted to light glows and not energy spectra, thus with Fig. 7 we only demonstrate that the time of NSEF outbursts coincides with maximums of the energy spectra.
Figure 9 is a wonderful picture of Aragats station, but does not add to much to the paper, I think it may be omitted.
Figure 9 demonstrates the location of the panoramic camera, surrounded by many masts. Thus, we illustrate the possibility of corona discharges, and the necessity to add new panoramic cameras to reject the corona discharge scenario for explaining all light glows.
The last sentence in 12 page. Was it simulated to estimate sensitivity of different stations (MAST, MAKET) located at different heights?
The sensitivity of sensors to measure the NSEF is very difficult to simulate. We calibrate all 4 devices at fair-weather. And we check the time of lightning detection with all 4 devices, which usually coincides with a millisecond time scale.
In the discussion there is statement about new luminous phenomena under clouds observed together with electric field disturbances. How accurate the altitude estimation is done not obvious. In line 279 it is written that lights are 100 m height while cloud – 90 m which contradicts the conclusion.
We compare glows that occurred on 22 and 25 May; sure, the estimates of the cloud base height are not precise and the cloud base itself is not an ideal plane surface, thus, as we state our rough estimate of cloud base is 25-60 m for May 22 and ≈ 90 m for May 25 what allows us only to make an assumption on the mean height of the light glows.
If it is blue jet or starter it will not terminate charge particle flux as well. These phenomena are not related to lightning and occurred in the periphery of a thunderstorm. So, the conclusion about new phenomena seems not to be very reliable. And other possibilities should be discussed and rid out.
Agree, corrections, and additional explanations are added to the discussion section.
Technical corrections
line 27: are à as
sentence corrected
line 27: “-“ should be deleted
line 41 and though out of the text: FoW – FoV (since it is fielf of View)
Changed
line 58: Using à using
line 72: Fig. 2a à Fig. 1a
line 74: HZ à Hz.
line 79: WWLN à WWLLN
line 85: 1-m2 à 1 m2 and the same correction through out of the text.
Numeration of parts! Always 1.
All misprints corrected, many thanks for comments and corrections!
Submission Date
17 May 2022
Date of this review
05 Jun 2022 17:47:27
Reviewer 2 Report
The authors provide fantastic observations of TGEs during active thunderstorms, and direct evidences show clear correlations between the TLES, NSEF, and TGEs. The results are novel, and the manuscript is well written, and worthy of publication. However, there are a few questions or comments that should be answered or addressed before the publication.
Firstly, I would like to suggest the authors add some context to introduce the timing system of the STAND1 particle detector network, and how the instruments are synchronized.
Secondly, the maximums of the correlation in Figure 4b) and d) are not located at 0 time, and they are shifted a least more than 10 seconds, which cannot support the statement “all 3 detectors show precisely coinciding time series of TGE count rates”.
Thirdly, the maximums of the electric field disturbances between the blue and black lines are separated by 30 seconds. The statement “Thus, we can conclude that field rearrangement first influences the GAMMA sensor, and only after 30 seconds - others”, is not clear. If they are influenced by the same field, the time delay should not be too large, I believe, they should detect the field at the same time. This means that the peaks in the blue and black lines are probably caused by different events. There is no evidence showing a clear correlation between the black line and the blue line. The same issue for Figure 18, the whole blue line seems to be left-shifted, not only the peaks, so it makes me speculate about the accuracy of the timing system of the detector network.
Minor comments:
Line 71, “1. Instrumentation” -> “2. Instrumentation”
104 “FPGA” means “Field Programmable Gate Arrays”. “programmable FPGA” is redundant, just “FPGA” should be fine.
Line 113-Line125 the font size of this paragraph is slightly larger and should be reduced.
Line 126, “1. Thundercloud extension, electric field…” -> “3. Thundercloud extension, electric field…”
Line 136, I would like to suggest adding scales on the map, so the readers will easily get the distances between the lighting sites and the stations.
Line 149 and 150, I would like to suggest changing the hyphen to “:”. They look like negative correlation values.
Line 156, the font size of the axes of Figure 4 a)—d) are not clear enough and hard to read.
Line 174, “In Fig.6” -> “In Fig. 6”, add a space.
Line 203, “hall and chimney” -> “hall and chimney”, delete a space.
Line 227, “ the southwest. According to”, delete a space.
Line 247, Figure 11c, the labels should be added on the red axis.
Line 279, “. and lights were very bright” -> “, and lights were very bright”
Line 282, the “black”, “blue”, and “red” plots are unreadable in Fig. 13.
Line 287, “1. Correlation analysis …” -> “4. Correlation analysis …”
Line 292, “… in Fig 14). All 8 TGEs …” -> “… in Fig. 14). All 8 TGEs …”, delete a space
Author Response
Comments and Suggestions for Authors
The authors provide fantastic observations of TGEs during active thunderstorms, and direct evidences show clear correlations between the TLES, NSEF, and TGEs. The results are novel, and the manuscript is well written, and worthy of publication. However, there are a few questions or comments that should be answered or addressed before the publication.
Firstly, I would like to suggest the authors add some context to introduce the timing system of the STAND1 particle detector network, and how the instruments are synchronized.
New Figure 2 is introduced, and explanations of the timing system are added.
Secondly, the maximums of the correlation in Figure 4b) and d) are not located at 0 time, and they are shifted a least more than 10 seconds, which cannot support the statement “all 3 detectors show precisely coinciding time series of TGE count rates”.
Agree, description is changed. The value of the correlation coefficient in frames 4 b and d is not significantly changed within 10c.
Thirdly, the maximums of the electric field disturbances between the blue and black lines are separated by 30 seconds. The statement “Thus, we can conclude that field rearrangement first influences the GAMMA sensor, and only after 30 seconds - others”, is not clear. If they are influenced by the same field, the time delay should not be too large, I believe, they should detect the field at the same time.
The time synchronization is provided by GPS time stamps and is not worse than 1 ms. The frequency of EFM operation is 20 Hz, thus the time series of NSEF are really precisely correlated. However, we cannot expect absolute coinciding of devices located at different altitudes and at distances ≈of 100-300 m. In Fig. 15 we see that the red curve (GAMMA, ≈300 m apart) is shifted by 30s relative to others and does not demonstrate the third peak. Sure, the black and blue curves are not identical, but for field measurements, in mountain regions, we cannot expect precise coincidences of time series of such a fast-changing parameter as NSEF.
This means that the peaks in the blue and black lines are probably caused by different events. There is no evidence showing a clear correlation between the black line and the blue line. The same issue for Figure 18, the whole blue line seems to be left-shifted, not only the peaks, so it makes me speculate about the accuracy of the timing system of the detector network.
In Fig. 18 the blue curve represents continuous monitoring of NSEF by EFM 100 located at GAMMA hall, 300 m apart from others and again it is ≈ a 30s delay. The TGE events are coinciding with deep negative NSEF. Sure, there are local differences between 4 devices, located at different heights and in different environments, however, we try to reveal the possible systematics, which can help to understand the causes of light glows.
In Fig.18
Minor comments:
Line 71, “1. Instrumentation” -> “2. Instrumentation”
104 “FPGA” means “Field Programmable Gate Arrays”. “programmable FPGA” is redundant, just “FPGA” should be fine.
Line 113-Line125 the font size of this paragraph is slightly larger and should be reduced.
Line 126, “1. Thundercloud extension, electric field…” -> “3. Thundercloud extension, electric field…”
Line 136, I would like to suggest adding scales on the map, so the readers will easily get the distances between the lighting sites and the stations.
The scale factor is added to maps.
Line 149 and 150, I would like to suggest changing the hyphen to “:”. They look like negative correlation values.
We change – to + to avoid confusing
Line 156, the font size of the axes of Figure 4 a)—d) are not clear enough and hard to read.
Line 174, “In Fig.6” -> “In Fig. 6”, add a space.
Line 203, “hall and chimney” -> “hall and chimney”, delete a space.
Line 227, “ the southwest. According to”, delete a space.
Line 247, Figure 11c, the labels should be added on the red axis.
The figure changed label added
Line 279, “. and lights were very bright” -> “, and lights were very bright”
Line 282, the “black”, “blue”, and “red” plots are unreadable in Fig. 13.
Sorry, the Figure was changed, but the caption remains the same, now corrected.
Line 287, “1. Correlation analysis …” -> “4. Correlation analysis …”
Line 292, “… in Fig 14). All 8 TGEs …” -> “… in Fig. 14). All 8 TGEs …”, delete a space
Misprints are corrected, Figures improved. Thank you very much for comments and corrections.
Submission Date
17 May 2022
Date of this review
Round 2
Reviewer 1 Report
The authors have addressed all my suggestions and the paper is improved.
Some minore corrections:
1) Quality of figures can be improved.
2) line 212 field of view is not necessary since FoV was already introduced.
3) figure 9 still there is FoW instead of FoV.
Author Response
There is no comments from reviewer 1 in the second round
