Dynamics of the Magnetotail Plasma Sheet Current

Round 1

Reviewer 1 Report

By focusing on several physical processes in the magnetotail, this article illustrates that some cases are more appropriately described in terms of electric fields and currents for magnetic flux transport and other physical processes. The starting point and purpose of the article are important, and the content is notable for advancing the study of the magnetospheric dynamics to greater accuracy and detail, as well as for enlightening possible magnetosphere-ionosphere coupling. I only have some minor suggestions to improve the article.

 

1.      Auroral beads (ABs) should be defined in line 63, not in line 327.

2.      THEMIS should be defined in line 133, not in Line 224.

3.      Lines 148 and 164, remove the period after“between”.

4.      Line 149, “agrees” should be “agree”.

5.      Line 413, “creates”should be “create”.

6.      Line 167, what is CR and how is it calculated?

7.      Line 169, please explain why “the FIC is invalid when CR is more than 2”.

8.      Figure 4, what does each panel show?

9.  Lines 245-249, please add “last panel of Figure 6” somewhere in this paragraph for clarification.

10.   Figure 6, please change Re in the last two panels to R_E for consistency.

11.  Figure 6, could you add a panel showing the E-field (with error bars if possible)? Is the variation of J dot E mainly caused by the current or the electric field?

12.   Figure 6, the Zgsm between the second and third panels is not aligned with X and Y.

13.   Line 284, 1996 should be 1966.

14.   Line 312, should “is” be “are”?

Author Response

I have responded to all your comments.

Author Response File: Author Response.docx

Reviewer 2 Report

Review report of the manuscript “Dynamics of the Magnetotail Plasma Sheet Current”, by A.T.Y. Lui.

 

The manuscript discusses and compares the merits and limitation of Bu and Ej paradigms in several case studies of magnetospheric related event, in which THEMIS data were analyzed. Two plasma instabilities are discussed and their relevance to substorm onset is evaluated. Physical insights gained in the Ej paradigm are found to be helpful in understanding these magnetospheric phenomena.

 

The major flaw of this manuscript is the origination. A significant part of the analysis (and Figures) is from the already published articles of the author's. I do not recommend the manuscript for publication.

Author Response

I have responded to your comments.

Author Response File: Author Response.docx

Reviewer 3 Report

A.T.Y.Lui  is widely known for his active participation in the discussion about Bu and Ej paradigm. Besides his point of view on the advantages and disadvantages of the Bu-Ej approaches, the reviewed paper gives a theory of the structures observed before the onset of a substorm (so called, “beads”) based on the cross-field current instability (CCI). In general, the paper turned out to be interesting and I recommend it for publication after revision.

Major Points

Since the author touched on the problem of Bu-Ej approaches, I would like to clarify his point of view on this issue.

1. What is the Bu approach is clearly defined only in the conclusion in lines 470-472, i.e. Bu approach is based on the use of ideal MHD. Then it becomes clear that such a defined approach is inapplicable for all those processes where dissipation is necessary, which violates freezing-inn conditions. I recommend moving this definition to the introduction.

2. The second remark concerns the scales on which dissipation is important. The paper considers only dissipation on proton scales when the right hand side of equation 3 can be neglected, and then E+UхB=0, where U is the mass velocity, i.e. protons speed. However, if the Hall term JxB/ne is moved to the left hand side, then it turns out that now E + U_e x B = 0, where U_e is the electron velocity, i.e. electrons unfreeze later than protons. For example,  reconnection  is impossible if the electrons are frozen, dissipation on electronic scales is important in this case. Runov's results (Figs. 2,3) are based on TEMIS data (proton scales, velocity U). Then it is interesting whether the electrons are frozen or not, they can also carry the magnetic flux. When describing Fig. 6 (CD diagram, line 442) it says "The electrons are tied to the magnetic field lines and move Earthward while  the ions lag behind", that is, in this case, dissipation is only important on the proton scale, and are the electrons still frozen in?

Minor Points

1. line 96 Move equation 3 to the right

2. line 138 How are dsl coordinates defined?

3. line 286 Move equation 4 to the right

4. line 311 Move equation 6 to the right

5. line 317 Check equation 7. In this equation, Omega_r is dimensionless, but then growth rate is also dimensionless, and should have a dimension of 1/sec. Missing normalization factor.

6. Fig 7, 8 are quite simple, I recommend putting them on one page.

7. Fig. 10a is too small, it is difficult to see anything. I recommend increasing it.

8. line 527 Written: Kozelov, T. V., and B. V. Kozelova Should be Kozelov, B. V., and T. V. Kozelova

Author Response

I have responded to all your comments.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

All of my comments have been addressed. I only have a few minor suggestions to improve the article.

 

1.      Line 34, remove the extra period after “satisfied”.

2.      Line 522, “Tthere” should be “There”.

3.      Since the variation of J dot E appears to be caused mainly by the electric field (Figure 6), can the author clarify the role of CD played in the power dissipation during a substorm?

Author Response

I thank the reviewer for the comments to further improving the manuscript. Specific responses to the comments are given below:

 

1. Correction made.

 

2. Correction made.

 

3. The following statement is added to the revised text:

Note that since the power dissipation is mainly caused by the electric field, the role of CCI in power dissipation during a substorm is the rapid magnetic field changes as a result of current changes caused by the CCI.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The paper by A.T.Y.Lui  Dynamics of the Magnetotail Plasma Sheet Current can be published after revision.

Minor corrections

Line 266 It is written:… gyroradius is ~391km~0.61 R_E

Must be: … gyroradius is ~391km~0.061 R_E

Line 330 Please check equation 7. It is written

Omega_r=k^2 c^2 cos^2 theta/omega^2_pe Hence Omega_r is dimensionless, but it has dimension 1/sec

Line 554 It is written:  Kozelov, TB. V., and BT. V. Kozelova

Must be: :  Kozelova, T. V., and B. V. Kozelov

Author Response

I thank the reviewer’s for more comments of the revised manuscript. Specific responses to the comments are given below:

 

1. Typo is corrected.

 

2. There is misunderstanding here. Omega_r is not normalized to be dimensionless but has the dimension of 1/sec as stated.

 

3. Correction made.

 

Author Response File: Author Response.docx