Electric current and magnetic field geometry in flapping magnetotail current sheets
Using four-point magnetic field measurements by the Cluster spacecraft, we statistically analyze the magnetic field and electric current configurations during rapid crossings of the current sheet observed in July-October 2001 at geocentric distances of 19 <i>R<sub>E</sub></i...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2005-06-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/23/1391/2005/angeo-23-1391-2005.pdf |
| _version_ | 1818652707972448256 |
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| author | A. Runov V. A. Sergeev W. Baumjohann R. Nakamura S. Apatenkov Y. Asano M. Volwerk M. Volwerk Z. Vörös T. L. Zhang A. Petrukovich A. Balogh J.-A. Sauvaud B. Klecker H. Rème |
| author_facet | A. Runov V. A. Sergeev W. Baumjohann R. Nakamura S. Apatenkov Y. Asano M. Volwerk M. Volwerk Z. Vörös T. L. Zhang A. Petrukovich A. Balogh J.-A. Sauvaud B. Klecker H. Rème |
| author_sort | A. Runov |
| collection | DOAJ |
| description | Using four-point magnetic field measurements by the Cluster
spacecraft, we statistically analyze the magnetic field and
electric current configurations during rapid crossings of the
current sheet observed in July-October 2001 at geocentric
distances of 19 <i>R<sub>E</sub></i>.
The database includes 78 crossings, specially selected to
apply multi-point data analysis techniques to calculate
vector derivatives.
Observed bipolar variations of <i>j<sub>z</sub></i>, often with | <i>j<sub>z</sub></i> |><i>j<sub>y</sub></i>,
indicate that the
electric currents follow kinks of the current sheet. The current
density varies between 5-25nA/m<sup>2</sup>. The half-thickness
of the current sheet during flapping varies over a wide range,
from 1 to 20 ion thermal gyroradii (<i>L<sub>cp</sub></i>), calculated
from average temperature and lobe magnetic field for each
crossing). We found no relationship between the tilt angle of the
current sheet normal and the half-thickness. In 68 cases the
magnetic field curvature vector has a positive (earthward)
<i>X</i>-component. Ten cases with a negative (tailward) curvature,
associated with reconnection, were detected within
0<<i>Y<sub>GSM</sub></i><7 <i>R<sub>E</sub></i>.
The minimum curvature radii vary mainly between 1 and
10 <i>L<sub>cp</sub></i>, and the adiabaticity parameter κ≤1 for 73% of the
events. The electric current density
during flapping is often off-central, i.e. the main current
density is shifted from the neutral sheet (| <i>B<sub>x</sub></i> |<5nT) to
the Northern or Southern Hemisphere. This is most likely a
temporal effect related to the flapping.
The analysis shows that the flapping motion of the current
sheet is associated with kink-like waves on the sheet
surface. The kink fronts, tilted in the <i>Y-Z</i>
plane, moved toward dawn in the morning half and toward dusk
in the evening half of the magnetotail. |
| first_indexed | 2024-12-17T02:26:18Z |
| format | Article |
| id | doaj.art-3a0a0d8fcd144b7ba319f8134bc3f6c2 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-17T02:26:18Z |
| publishDate | 2005-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-3a0a0d8fcd144b7ba319f8134bc3f6c22022-12-21T22:07:06ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762005-06-01231391140310.5194/angeo-23-1391-2005Electric current and magnetic field geometry in flapping magnetotail current sheetsA. Runov0V. A. Sergeev1W. Baumjohann2R. Nakamura3S. Apatenkov4Y. Asano5M. Volwerk6M. Volwerk7Z. Vörös8T. L. Zhang9A. Petrukovich10A. Balogh11J.-A. Sauvaud12B. Klecker13H. Rème14Space Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaSt. Petersburg University, RussiaSpace Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaSpace Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaSt. Petersburg University, RussiaSpace Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaMPE, Garching, GermanySpace Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaSpace Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaSpace Research Institute, Austrian Academy of Sciences, A-8042, Graz, AustriaSpace Research Institute, Russian Academy of Sciences, Moscow, RussiaImperial College, London, UKCESR, Toulouse, FranceMPE, Garching, GermanyCESR, Toulouse, FranceUsing four-point magnetic field measurements by the Cluster spacecraft, we statistically analyze the magnetic field and electric current configurations during rapid crossings of the current sheet observed in July-October 2001 at geocentric distances of 19 <i>R<sub>E</sub></i>. The database includes 78 crossings, specially selected to apply multi-point data analysis techniques to calculate vector derivatives. Observed bipolar variations of <i>j<sub>z</sub></i>, often with | <i>j<sub>z</sub></i> |><i>j<sub>y</sub></i>, indicate that the electric currents follow kinks of the current sheet. The current density varies between 5-25nA/m<sup>2</sup>. The half-thickness of the current sheet during flapping varies over a wide range, from 1 to 20 ion thermal gyroradii (<i>L<sub>cp</sub></i>), calculated from average temperature and lobe magnetic field for each crossing). We found no relationship between the tilt angle of the current sheet normal and the half-thickness. In 68 cases the magnetic field curvature vector has a positive (earthward) <i>X</i>-component. Ten cases with a negative (tailward) curvature, associated with reconnection, were detected within 0<<i>Y<sub>GSM</sub></i><7 <i>R<sub>E</sub></i>. The minimum curvature radii vary mainly between 1 and 10 <i>L<sub>cp</sub></i>, and the adiabaticity parameter κ≤1 for 73% of the events. The electric current density during flapping is often off-central, i.e. the main current density is shifted from the neutral sheet (| <i>B<sub>x</sub></i> |<5nT) to the Northern or Southern Hemisphere. This is most likely a temporal effect related to the flapping. The analysis shows that the flapping motion of the current sheet is associated with kink-like waves on the sheet surface. The kink fronts, tilted in the <i>Y-Z</i> plane, moved toward dawn in the morning half and toward dusk in the evening half of the magnetotail.https://www.ann-geophys.net/23/1391/2005/angeo-23-1391-2005.pdf |
| spellingShingle | A. Runov V. A. Sergeev W. Baumjohann R. Nakamura S. Apatenkov Y. Asano M. Volwerk M. Volwerk Z. Vörös T. L. Zhang A. Petrukovich A. Balogh J.-A. Sauvaud B. Klecker H. Rème Electric current and magnetic field geometry in flapping magnetotail current sheets Annales Geophysicae |
| title | Electric current and magnetic field geometry in flapping magnetotail current sheets |
| title_full | Electric current and magnetic field geometry in flapping magnetotail current sheets |
| title_fullStr | Electric current and magnetic field geometry in flapping magnetotail current sheets |
| title_full_unstemmed | Electric current and magnetic field geometry in flapping magnetotail current sheets |
| title_short | Electric current and magnetic field geometry in flapping magnetotail current sheets |
| title_sort | electric current and magnetic field geometry in flapping magnetotail current sheets |
| url | https://www.ann-geophys.net/23/1391/2005/angeo-23-1391-2005.pdf |
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