The Algorithm of the Two Neutron Monitors for the Analysis of the Rigidity Spectrum Variations of Galactic Cosmic Ray Intensity Flux in Solar Cycle 24

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

The article analyzes the parameters of the rigidity spectrum variations (RSV) of galactic cosmic ray intensity (GCR) flux in the 24th solar cycle based on data from the global network of neutron monitors. The method helps determine cosmic ray mean free path dependency on rigidity and consequently structure of the heliospheric magnetic field (HMF).

 

 

Generally, the manuscript presents a valuable alternative method to determine the structure of HMF during the solar cycle, specifically during 24. solar cycle. I recommend the article be published after minor revision.

 

 

I have a few minor comments

 

1. The least squares method mentioned in the article should be cited.
2. The RSV function shown in lines 30-31 is somehow higher over parenthesis. Improve the formatting of text in those lines.
3. Also, formula (2) at line 76 and formula at line 78 are not well centered.
4. When the flux in the heliosphere is mentioned, as in the sentence on line 230, I would be more specific. Authors could say, for example, flux in the heliosphere entering Earth's magnetosphere, or "flux in the heliosphere at 1AU at ecliptic plane outside of Earth's magnetosphere", or a similar form describing a position in heliosphere which we are talking about.
5. The technical editor of the article notices, that MDPI rules recommend that authors should not engage in excessive self-citation of their own work (https://www.mdpi.com/ethics#_bookmark20). To address this I recommend for example adding citations to show that the two monitor method and the least squares method give similar results.

 

 

I have two questions for manuscript authors.

 

 

1. Are there other integral coupling coefficients except for the used taken from [Yassue, 1982], which did you consider? And, if yes, why did you choose [Yassue, 1982] coefficients?
2. Why Oulu, Potchefstroom, Apatity, Mexico neutron monitor were chosen? Why those and not some other neutron monitors from nmdb network?

 

Author Response

Comments 1: The least squares method mentioned in the article should be cited.

Response  1: We add  The least squares method mentioned in the article in appendix.

Comments 2:The RSV function shown in lines 30-31 is somehow higher over parenthesis. Improve the formatting of text in those lines.

Response 2: Thank You for your remark. We improve format of whole manuscript

Comments 3. Also, formula (2) at line 76 and formula at line 78 are not well centered.

Response  3: We improve format of equations

Comments 4.: When the flux in the heliosphere is mentioned, as in the sentence on line 230, I would be more specific. Authors could say, for example, flux in the heliosphere entering Earth's magnetosphere, or "flux in the heliosphere at 1AU at ecliptic plane outside of Earth's magnetosphere", or a similar form describing a position in heliosphere which we are talking about.

Response  4: Thank You for your remark. We have changed the text according to your comment.

Comments 5: The technical editor of the article notices, that MDPI rules recommend that authors should not engage in excessive self-citation of their own work (https://www.mdpi.com/ethics#_bookmark20). To address this I recommend for example adding citations to show that the two monitor method and the least squares method give similar results.

Response  4: We have reduced the number of citations to our works by 9. in the text and in the literature you can see which works have been removed - crossed out on a yellow background.

I have two questions for manuscript authors.

1.Are there other integral coupling coefficients except for the used taken from [Yassue, 1982], which did you consider? And, if yes, why did you choose [Yassue, 1982] coefficients?

There is also a method based on yield function developed by Oulu Team: Alexander L. Mishev, Sergey A. Koldobskiy, Gennady A. Kovaltsov, Agnieszka Gil, Ilya G. Usoskin, Updated Neutron-Monitor Yield Function: Bridging Between In Situ and Ground-Based Cosmic Ray Measurements,

https://doi.org/10.1029/2019JA027433

The yield function method works in a wide energy range, and is especially dedicated to the Study of Ground-level Enhancement Events of Solar Energetic Particles (for low energy particles e.g SEP, less then an effective registration energy for neutron montors ) See paper:

https://iopscience.iop.org/article/10.3847/1538-4357/acfee8

The Yasue coefficient method works well for particles with an effective registration energy of 10-25 GV (for higer energy particles for Neutron Monitors).

 

2. Why Oulu, Potchefstroom, Apatity, Mexico neutron monitor were chosen? Why those and not some other neutron monitors from nmdb network?

 

Four of approximately 50 neutron monitors currently in operation were selected based on data continuity and stability. The pairs of monitors are selected so that their cut-off rigidity differs significantly (condition for the correctness of the two-station method). This method does not work for two monitors with similar cutoff rigidity. In this situation we would actually be dealing with 1 monitor.

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is well structured and written. The methodology and the results appear scientifically sound. The bibliography is appropriate. Overall, the manuscript is well suited for publication in Universe. The presentation of the results can be improved. For example the quality of the figures, e.g. the axis labels and titles can be made more readable; the layout of the paper should be improved as well, as figures and equation do not fit in the margins; many inline equations appear unreadable. 

Author Response

Comment 1:  The manuscript is well structured and written. The methodology and the results appear scientifically sound. The bibliography is appropriate. Overall, the manuscript is well suited for publication in Universe. The presentation of the results can be improved. For example the quality of the figures, e.g. the axis labels and titles can be made more readable; the layout of the paper should be improved as well, as figures and equation do not fit in the margins; many inline equations appear unreadable. 

Response 1: Thank You for your remark. We improve presentation of whole manuscript

Reviewer 3 Report

Comments and Suggestions for Authors

The paper launches a new data analysis method as an alternative to the least squares method when there are only few neutron monitors working stably in a given period. The effect of the method is impressive. The paper deserves to be published, but before it, there are several questions as follows should be clarified:

During analysis, two pairs of neutron monitors are coped with individually, are not they? If yes, why in Fig. 6 are all four curves finally moved together, compared with Fig. 1? Why do not they separate into two pairs?

Data of two pairs of neutron monitors are used in analysis: Oulu-Potchefstroom and Apatity-Mexico. Why to take such a combination? In Fig. 1 it is obvious that Potchefstroom and Mexico have more closed amplitude of change, so do Oulu and Apatity. Has it been attempted to combine Potchefstroom- Mexico and Oulu- Apatity? What difference in results?

To test if the new method is a good alternative to the least squares method, it is better to select a set of good, perfect data to perform both the least squares method and this new method to compare their results directly.  Or to take a simulation?

Conclusion ii) Why does one cycle (2009-2019) confirm that all 11 cycles?

Comments on the Quality of English Language

English of the paper should be upgraded. There are several grammatical problems. For example:

“24 Solar Cycle” should be “Solar Cycle 24”.

In abstract: “were found” should be “were found”

Line 236: it should be “From Figure 6 there is not any difference among Oulu, Potchefstroom, Apatity and Mexico NMs data in terms of correctness of calculations.”

Line 241: it should be “particles with higher energy”.

In the paper, sometimes “gamma exponent”, but sometimes “gamma parameter”. For example, line 246-247.

Author Response

Comment 1: During analysis, two pairs of neutron monitors are coped with individually, are not they? If yes, why in Fig. 6 are all four curves finally moved together, compared with Fig. 1? Why do not they separate into two pairs?

Response 1: 

Fig. 6 shows all 4 curves determined on the basis of the method used and the determined gamma parameter.

After converting each neutron monitor's data to the heliosphere based on coupling coefficients, the determined values ​​should be within the accuracy range

For this purpose, it is better to present all 4 values ​​in one figure no. 6 in order to confirm the obtained results.

Comment 2: Data of two pairs of neutron monitors are used in analysis: Oulu-Potchefstroom and Apatity-Mexico. Why to take such a combination? In Fig. 1 it is obvious that Potchefstroom and Mexico have more closed amplitude of change, so do Oulu and Apatity. Has it been attempted to combine Potchefstroom- Mexico and Oulu- Apatity? What difference in results?

Response 2: 

Four of approximately 50 neutron monitors currently in operation were selected based on data continuity and stability. The pairs of monitors are selected so that their cut-off rigidity differs significantly (condition for the correctness of the two-station method). This method does not work for two monitors with similar cutoff rigidity. In this situation we would actually be dealing with 1 monitor.

Comment 3: To test if the new method is a good alternative to the least squares method, it is better to select a set of good, perfect data to perform both the least squares method and this new method to compare their results directly.  Or to take a simulation? 

Conclusion ii) Why does one cycle (2009-2019) confirm that all 11 cycles?

Response 3: 

Earlier research (1960s) with a small number of operating neutron monitors required the use of the 2 neutron monitor method. e.g. (Alania, Iskra,  1995). Then the least squares method was used, because data from a larger number of detectors were available.

The above two methods confirm the global nature of changes in the variation spectrum GCR, i.e. at the maximum the variation spectrum is soft γ = 1.2-1.3., and at the minimum the GCR variation spectrum is hard γ = 0.6-0.9,

The proposed study is very interesting, we will try to perform such a simulation in our next work

In the work in 2018, https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017JA023994 

the least squares method was used in the period 1969-2011 to calculate the value of the gamma coefficient. Previously, these two methods were already compared in the years 1980-1987, see the worksin1995 https://www.sciencedirect.com/science/article/pii/027311779500343D?via%3Dihub 

and partially in the work by Siluszyk JGR 2018 Interplanetary Magnetic Field Turbulence and Rigidity Spectrum of the Galactic Cosmic Rays Intensity Variation (1969–2011) M. Siluszyk, M. V. Alania, K. Iskra, S. Miernicki

 

Comments 4: on the Quality of English Language

English of the paper should be upgraded. There are several grammatical problems.

For example: “24 Solar Cycle” should be “Solar Cycle 24”.

In abstract: “were found” should be “were found”

Line 236: it should be “From Figure 6 there is not any difference among Oulu, Potchefstroom, Apatity and Mexico NMs data in terms of correctness of calculations.”

Line 241: it should be “particles with higher energy”.

In the paper, sometimes “gamma exponent”, but sometimes “gamma parameter”. For example, line 246-247.

Response 4: Thank You. We agree and we have changed all your remarks.  

 

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Thanks to the authors for the responses. No more comments.

Comments on the Quality of English Language

Only one comment: In abstract, "24 solar cycle" should be "solar cycle 24", and line 172, 178, "solar cycle 24" is better. 

Author Response

Dear Reviewer 

Thank you very much for your reviews.

The comments turned out to be very important and valuable.

Thanks to them, the work has been significantly improved.

I have taken into account all comments and defects

In the corrected work you can see the changes marked in colors, initially red, now blue, I marked the deletions with a strikethrough

Kind regards,