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| Titel |
Ionospheric signatures during a magnetospheric flux rope event |
| VerfasserIn |
L. Juusola, O. Amm, H. U. Frey, K. Kauristie, R. Nakamura, C. J. Owen, V. Sergeev, J. A. Slavin, A. Walsh |
| 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 ; 26, no. 12 ; Nr. 26, no. 12 (2008-12-05), S.3967-3977 |
| Datensatznummer |
250016323
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| Publikation (Nr.) |
 copernicus.org/angeo-26-3967-2008.pdf |
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| Zusammenfassung |
| On 13 August 2002, during a substorm, Cluster encountered two earthward moving
flux ropes (FR) in the central magnetotail. The first FR was observed during
the expansion phase of the substorm, and the second FR during the recovery
phase. In the conjugate ionospheric region in Northern Fennoscandia, the
ionospheric equivalent currents were observed by the MIRACLE network and the
auroral evolution was monitored by the Wideband Imaging Camera (WIC) on-board
the IMAGE satellite. Extending the study of Amm et al. (2006), we examine and
compare the possible ionospheric signatures associated with the two FRs.
Amm et al. studied the first event in detail and found that the
ionospheric footprint of Cluster coincided with a region of downward
field-aligned current. They suggested that this region of downward current,
together with a trailing region of upward current further southwestward,
might correspond to the ends of the FR. Unlike during the first FR, however,
we do not see any clear ionospheric features associated with the second one.
In the GSM xy-plane, the first flux rope axis was tilted with respect to
the y-direction by 29°, while the second flux rope axis was
almost aligned in the y-direction, with an angle of 4° only.
It is possible that due to the length and orientation of the second FR, any
ionospheric signatures were simply mapped outside the region covered by the
ground-based instruments. We suggest that the ground signatures of a FR
depend on the orientation and the length of the structure. |
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