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| Titel |
Superposed epoch analysis applied to large-amplitude travelling convection vortices |
| VerfasserIn |
H. Lühr, M. Rother, T. Iyemori, T. L. Hansen, R. P. Lepping |
| 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 ; 16, no. 7 ; Nr. 16, no. 7, S.743-753 |
| Datensatznummer |
250013335
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| Publikation (Nr.) |
 copernicus.org/angeo-16-743-1998.pdf |
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| Zusammenfassung |
For the six months from 1 October 1993 to 1
April 1994 the recordings of the IMAGE magnetometer network have been surveyed
in a search for large-amplitude travelling convection vortices (TCVs). The
restriction to large amplitudes (>100 nT) was chosen to ensure a proper
detection of evens also during times of high activity. Readings of all stations
of the northern half of the IMAGE network were employed to check the consistency
of the ground signature with the notation of a dual-vortex structure moving in
an azimuthal direction. Applying these stringent selection criteria we detected
a total of 19 clear TCV events. The statistical properties of our selection
resemble the expected characteristics of large-amplitude TCVs. New and
unexpected results emerged from the superposed epoch analysis. TCVs tend to form
during quiet intervals embedded in moderately active periods. The occurrence of
events is not randomly distributed but rather shows a clustering around a few
days. These clusters recur once or twice every 27 days. Within a storm cycle
they show up five to seven days after the commencement. With regard to solar
wind conditions, we see the events occurring in the middle of the IMF sector
structure. Large-amplitude TCVs seem to require certain conditions to make solar
wind transients 'geoeffective', which have the tendency to recur with the solar
rotation period.
Key words. Ionosphere (Aural ionosphere; Ionosphere-
magnetosphere interactions) · Magnetospheric Physics (current system) |
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