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| Titel |
Non-storm irregular variation of the Dst index |
| VerfasserIn |
S. Nakano, T. Higuchi |
| 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 ; 30, no. 1 ; Nr. 30, no. 1 (2012-01-16), S.153-162 |
| Datensatznummer |
250017171
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| Publikation (Nr.) |
 copernicus.org/angeo-30-153-2012.pdf |
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| Zusammenfassung |
| The Dst index has a long-term variation that is not associated
with magnetic storms.
We estimated the long-term non-storm component of the Dst variation
by removing the short-term variation related to magnetic storms.
The results indicate that the variation of the non-storm component includes
not only a seasonal variation but also an irregular variation.
The irregular long-term variation is likely to be due to an anti-correlation
with the long-term variation of solar-wind activity.
In particular, a clear anti-correlation is observed between
the non-storm component of Dst and the long-term variation
of the solar-wind dynamic pressure.
This means that in the long term, the Dst index tends
to increase when the solar-wind dynamic pressure decreases.
We interpret this anti-correlation as an indication that the long-term
non-storm variation of Dst is influenced by the tail current
variation. The long-term variation of the solar-wind dynamic pressure
controls the plasma sheet thermal pressure, and the change of the plasma
sheet thermal pressure would cause the non-storm tail current variation,
resulting in the non-storm variation of Dst. |
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