Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.585 IF 1.585
  • IF 5-year value: 1.698 IF 5-year
    1.698
  • CiteScore value: 1.62 CiteScore
    1.62
  • SNIP value: 0.820 SNIP 0.820
  • IPP value: 1.52 IPP 1.52
  • SJR value: 0.781 SJR 0.781
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 83 Scimago H
    index 83
  • h5-index value: 24 h5-index 24
Discussion papers
https://doi.org/10.5194/angeo-2020-3
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-2020-3
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: regular paper 28 Jan 2020

Submitted as: regular paper | 28 Jan 2020

Review status
This preprint is currently under review for the journal ANGEO.

Relation between the asymmetric ring current effect and the anti-sunward auroral currents, as deduced from CHAMP observations

Hermann Lühr1 and Yun-Liang Zhou2 Hermann Lühr and Yun-Liang Zhou
  • 1GFZ, German Research Centre for Geosciences, Section 2.3, Geomagnetism, 14473 Potsdam, Germany
  • 2Department of Space Physics, School of Electronic Information, Wuhan University, 430072 Wuhan, China

Abstract. During magnetically active periods the storm-time disturbance signal on ground develops commonly an azimuthal asymmetry. Negative deflections of the magnetic horizontal (H) component are enhanced in the 18:00 local time sector and smallest in the morning sector. This is commonly attributed to the asymmetric ring current effect. In this study we are investigating the average characteristics of anti-sunward net currents that are not closing in the ionosphere. Their intensity is growing proportionally with the amount of solar wind input to the magnetosphere. There is almost twice as much current flowing in the winter hemisphere as on the summer side. This seasonal dependence is more pronounced on the dusk than on the dawn side. Event studies reveal that anti-sunward currents are closely related to the main phase of a magnetic storm. Since also the asymmetry of storm-time disturbances build up during the main phase, we suggest a relation between these two phenomena. From a statistical study of ground-based disturbance levels during magnetically active periods we obtain support for our suggestion. Observed storm-time disturbance amplitudes are clearly smaller in the summer hemisphere than in the winter part. This difference increases toward higher latitudes. We propose a new 3D current system responsible for the zonally asymmetric storm-time disturbance signal that does not involve the ring current. The high-latitude anti-sunward currents are connected at their noon and midnight ends to field-aligned currents that lead the currents to the outer magnetosphere. The net current branch on the morning side is closed along the dawn flank plasmapause, and the evening side currents along the dusk flank magnetopause. Regardless through which loop the current is flowing, near-Earth storm-time disturbance level will in both cases be reduced in the morning sector and enhanced in the evening.

Hermann Lühr and Yun-Liang Zhou

Interactive discussion

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Login for Authors/Topical Editors] [Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Hermann Lühr and Yun-Liang Zhou

Data sets

CH-ME-3-MAG - CHAMP 1 Hz combined magnetic field time series (Level 3). M. Rother and I. Michaelis https://doi.org/10.5880/GFZ.2.3.2019.004

Hermann Lühr and Yun-Liang Zhou

Viewed

Total article views: 152 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
119 31 2 152 0 0
  • HTML: 119
  • PDF: 31
  • XML: 2
  • Total: 152
  • BibTeX: 0
  • EndNote: 0
Views and downloads (calculated since 28 Jan 2020)
Cumulative views and downloads (calculated since 28 Jan 2020)

Viewed (geographical distribution)

Total article views: 123 (including HTML, PDF, and XML) Thereof 121 with geography defined and 2 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 06 Apr 2020
Publications Copernicus
Download
Short summary
During magnetic storms the magnetic disturbance at low latitudes becomes asymmetric, enhanced in the evening sector and reduced around morning. This has been attributed to the asymmetric ring current. Here a new 3D current system is proposed for explaining the asymmetric signal. Anti-sunward net currents at high latitude are connected at their noon and night ends to field-aligned currents that lead the currents to the magnetopause on the dawn and dusk flanks where the current closure occurs.
During magnetic storms the magnetic disturbance at low latitudes becomes asymmetric, enhanced in...
Citation