Strong southward and northward currents observed in the inner plasma sheet

Yang, Yan-Yan; Shen, Chao; Ji, Yong

doi:https://doi.org/10.5194/angeo-37-931-2019

Articles | Volume 37, issue 5

https://doi.org/10.5194/angeo-37-931-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/angeo-37-931-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 37, issue 5

Regular paper

|

10 Oct 2019

Regular paper |

| 10 Oct 2019

Strong southward and northward currents observed in the inner plasma sheet

Yan-Yan Yang, Chao Shen, and Yong Ji

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Final revised paper (published on 10 Oct 2019)
Preprint (discussion started on 15 Apr 2019)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Reviewer’s report on angeo-2019-56', Anonymous Referee #1, 13 Jun 2019
- AC1: 'Response to Referee #1', Yanyan Yang, 26 Jun 2019
RC2: 'Review of "Strong Southward and Northward Currents Observed in the Inner Plasma Sheet", by Yang et al.', Anonymous Referee #2, 19 Jun 2019
- AC2: 'Response to Referee #2', Yanyan Yang, 22 Jul 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Publish subject to revisions (further review by editor and referees) (01 Aug 2019) by Minna Palmroth

AR by Yanyan Yang on behalf of the Authors (02 Aug 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (02 Aug 2019) by Minna Palmroth

RR by Anonymous Referee #1 (26 Aug 2019)

RR by Anonymous Referee #2 (30 Aug 2019)

Suggestions for revision or reasons for rejection

Reviewer's report on revised manuscript "Strong Southward and Northward Currents Observed in the Inner Plasma Sheet", by Yang et al.

I would like to thank the authors for extensively improving the manuscript in agreement with my requests. The clarity of the manuscript has been improved greatly, and I would recommend publication with only a few minor corrections. In the future, however, I would urge the authors to prepare their manuscripts so that interim results such as the power-law fits, not included in the manuscript, would not be of such importance to the assessment of validity of the manuscript.

The magnitude analysis is convincing, and the restructuring has improved the flow and focus of the manuscript significantly. The explanations from the authors have also cleared some misinterpretations on my behalf.

I would suggest the authors elaborate the abstract somewhat so it better describes the actual analysis of energetic particle fluxes.

A few notes:

The fits of a and kappa to CODIF data were performed in the perpendicular direction (pitch angle of 90 degrees), whereas the equation for j_c uses parallel pressure. What was the reasoning for this? Assuming fits at pitch-angles close to 0 or 180 degrees provide similar results, I am content with the analysis, and leave this assessment to the authors.

For the aforementioned fits, the four dots available in RAPID data actually indicate a very different power law than what CODIF sees (if you fit to only the RAPID portion of data), although they can be placed at the continuation point of the CODIF power law. I would urge the authors to be careful of extrapolations up to 1 MeV (or beyond) based on these fits.

minor corrections:

page 4, line 13: I believe this should read polar, not azimuthal? For this event, the green curves are the ones showing a difference. For the March 31st event, there is a small storm-time deviation in the azimuthal component, but there as well it's the polar angle which deviates the most, I believe.

page 13, lines 5-6: I would recommend the authors add a mention that during the storm time, currents calculated via energetic particle fluxes appear to still underestimate the current. In fact, this could be discussed in the conclusions as follows: As the particle flux fit method of calculating currents works so well earlier in the time period, this undershoot during storm time might be indicative of additional energetic particle acceleration (a harder power law) in the parallel direction. This increased parallel pressure would result in the observed larger value of j_c. It is hypothetical, but could be verified by comparing CODIF and RAPID measurements at other storm events.

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ED: Publish subject to technical corrections (09 Sep 2019) by Minna Palmroth

AR by Yanyan Yang on behalf of the Authors (10 Sep 2019) Author's response Manuscript

Short summary

Previous studies show that the ring current (RC) and field-aligned currents (FACs) are the dominant currents in the inner magnetosphere. However, through two large storm events observed by Cluster, we find new strong southward and northward currents in the latitudinal region from 10° N to 30° N. Theoretical analysis indicates that these currents originated from the fluctuation of magnetic field lines during strong geomagnetic storms.