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| Titel |
Multiple current sheets in a double auroral oval observed from the MAGION-2 and MAGION-3 satellites |
| VerfasserIn |
M. Echim, M. Ciobanu, O. Balan, A. Blagau, O. Marghitu, E. Georgescu, Y. I. Galperin, N. V. Jorgio, T. M. Muliarchik, A. L. Kotikov, E. M. Shishkina, O. A. Troshichev |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 15, no. 4 ; Nr. 15, no. 4, S.412-423 |
| Datensatznummer |
250012727
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| Publikation (Nr.) |
 copernicus.org/angeo-15-412-1997.pdf |
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| Zusammenfassung |
| A case is described of multiple current
sheets crossed by the MAGION-2 satellite in the near-midnight quieting auroral
oval. The data were obtained by the magnetometer experiment onboard. Results
show during a quieting period after a preceding substorm, or during an early
growth phase of the next substorm, two double-sheet current bands, POLB and EQUB,
located at respectively the polar and equatorial borders of the auroral oval
separated by about 500 km in latitude. This is consistent with the double-oval
structure during recovery introduced by Elphinstone et al. (1995). Within
the POLB, the magnetic field data show simultaneous existence of several narrow
parallel bipolar current sheets within the upward current branch (at 69.5–70.3°
invariant latitude) with an adjacent downward current branch at its polar side
at (70.5–71.3°). The EQUB was similarly stratified and located at 61.2–63.5°
invariant latitude. The narrow current sheets were separated on average by about
35 km and 15 km, respectively, within the POLB and EQUB. A similar case of
double-oval current bands with small-scale structuring of their upward current
branches during a quieting period is found in the data from the MAGION-3
satellite. These observations contribute to the double-oval structure of the
late recovery phase, and add a small-scale structuring of the upward currents
producing the auroral arcs in the double- oval pattern, at least for the cases
presented here. Other observations of multiple auroral current sheets and
theories of auroral arc multiplicity are briefly discussed. It is suggested that
multiple X-lines in the distant tail, and/or leakage of energetic particles and
FA currents from a series of plasmoids formed during preceding magnetic
activity, could be one cause of highly stratified upward FA currents at the
polar edge of the quieting double auroral oval. |
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