The Electric Properties of the Magnetopause Boundary Layer

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

Second referee report on the article

Electric properties of the magnetopause boundary layer

by Gao et al.

 The manuscript underwent significant revision but the resulting text is generally of worse quality than the original version. Moreover, the authors do not react on my comment on determination of the errors properly, probably because they do not understand the core of my objection. It seems that the charge density is determined from the magnetopause current that is computed as curlB because otherwise I do not see the reason for the calculation of the current. However, the principal contributor to the magnetopause current is gradB drift that is present regardless of the charge imbalance. Since gradB drift is caused by the motion of all charged particles, the charge imbalance that is six orders of magnitude lower than the particle density itself can be simple the product of errors in calculations. The other possibility is charge density calculation from the electric field measurements according to the equation given in line 58. The authors estimate a possible contribution of the magnetopause motion to the electric field in lines 119-125 and conclude that it is negligible but my rough guess is 10% for the first and 40% for the second case which is not so small. However, the magnetopause velocity from multipoint measurements is an average and it can be significantly enhanced locally and the error can be much larger.

I think that the method of charge calculation as well as the possible systematic and statistical errors should be properly discussed prior publication. Moreover, the manuscript (mainly revised parts) contains many misprints, unclear statements, etc. that should be corrected. I am giving several examples but the list is far from being complete.  

Line 7 – comma is missing “….solar wind, the magnetosheath……

Line 10 – types instead of typies

Line 16 – keywords are missing

Lines 20, 21 – the statement there is misleading. The solar wind plasma enters magnetosphere by different process permanently, not only during the storms. Moreover, if IMF points northward during the storm, the solar wind input can be negligible in comparison with non-storm times.

Line 52 – what the electric density features mean?

Lines 87, 88 – the section 2 lists the criteria for selection of events, but the item d is rather a partial conclusion.

Line 90 – I would suggest to correct the wording, eg. Using the procedure described above, 82 burst mode intervals were selected.

Figure 1 – what the blue vertical lines stand for?

Line 212 – “cosusoidal” would be probably cosinusoidal.

Comments on the Quality of English Language

See above

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

Authors have improved the manuscript and it can be published in the journal in the current submitted  form

Author Response

We wanted to take a moment to express my sincere gratitude for the time and effort you dedicated to reviewing our manuscript.Your constructive feedback and positive evaluation are truly appreciated.

 

Round 2

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

Third referee report on the article

The electric properties of the magnetopause boundary layer

by Gao et al.

 

The resubmitted manuscript is in much better shape and it requires a minor revision to be clear for readers.

-       The search for the magnetopause crossing using the parameter alpha is rather non-traditional but the value of 170 was chosen arbitrary and Fig. 1 documents that it does not provide the position of the crossing that was clearly observed several second later, at the time of steepest gradient of all parameters. Although the exact position of the magnetopause is not important for the present study, it would be mentioned.

-       The method of calculation of the charge density should be described in detail. As I understood, it is computed from divergence E (line 61). However, it requires some assumption on the spatial distribution of E but the spacecraft provide time series. The procedure od determination of spatial structure of E should be described in detail.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Referee report on the article

Electric properties of the magnetopause boundary layer

by Gao et al.

The manuscript deals with the investigation of the charge layers adjacent to magnetopause. The authors use MMS plasma and magnetic and electric field data gathered in the burst mode for computation of the charge density. Based on their analysis, the authors argue that the dusk magnetopause exhibits negative net charge outside and positive inside whereas the opposite is true on the dawn side. However, the summary Figure 5 shows that the layer of negative charge is not present in many cases and the problem of this charge imbalance is not discussed. The charge density determined by their procedures is of the order of units of electron charges in m^3, i.e. six orders of magnitude below the particle number density. This disproportion evokes question on the uncertainty of the charge density determination and without addition of estimates of the systematic and statistical errors and their careful discussion the paper cannot be published.  

Comments on the Quality of English Language

English of the article is acceptable without corrections.

Reviewer 2 Report

Comments and Suggestions for Authors

Authors try to study the MMS data to present a new results on magnetopause structure. But for unclear for me reasons they submit the manuscript to the journal that did not connected to the subject. If we research of the list of references we did not saw any referenced magnetochemistry papers. It is essential because the space plasma physics discussed in Plasma Physics, Astrophysical Journal, Journal of Geophysical Research  and etc. My question to Editor: Do you want to change of the area of journal interest or you want to review a manuscript without discussion with an experts in the magnetopause current sheet investigation?

 

And more specific comments that explained my conclusion: I propose to reject the paper.

1.     The introduction did not presented a short review of previous paper with a history (about 60 years in sity observations) of the magnetopause and similar space current study. 

2.     To use the LMN approach to present a spacecraft data with crossing a moving current sheet you are needed a priori model. And this model must be introduced in the text&

3.     It is unclear for me what subject they named “the magnetopause layer”

4.     I did not understood what kind of the model have used in the study : MHD, kinetic with single particle trajectory, 

5.     What is about a Debay screening of the electric charge?  

 

 

 

 

Comments for author File: Comments.pdf