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| Titel |
The driving mechanisms of particle precipitation during the moderate geomagnetic storm of 7 January 2005 |
| VerfasserIn |
N. Longden, F. Honary, A. J. Kavanagh, J. Manninen |
| 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 ; 25, no. 9 ; Nr. 25, no. 9 (2007-10-02), S.2053-2068 |
| Datensatznummer |
250015920
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2053-2007.pdf |
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| Zusammenfassung |
| The arrival of an interplanetary coronal mass ejection (ICME) triggered a
sudden storm commencement (SSC) at ~09:22 UT on the 7 January 2005. The
ICME followed a quiet period in the solar wind and interplanetary magnetic
field (IMF). We present global scale observations of energetic electron
precipitation during the moderate geomagnetic storm driven by the ICME.
Energetic electron precipitation is inferred from increases in cosmic noise
absorption (CNA) recorded by stations in the Global Riometer Array (GLORIA).
No evidence of CNA was observed during the first four hours of passage of the
ICME or following the sudden commencement (SC) of the storm. This is
consistent with the findings of Osepian and Kirkwood (2004) that SCs will only
trigger precipitation during periods of geomagnetic activity or when the
magnetic perturbation in the magnetosphere is substantial. CNA was only
observed following enhanced coupling between the IMF and the magnetosphere,
resulting from southward oriented IMF. Precipitation was observed due to
substorm activity, as a result of the initial injection and particles
drifting from the injection region. During the recovery phase of the storm,
when substorm activity diminished, precipitation due to density driven
increases in the solar wind dynamic pressure (Pdyn) were
identified. A number of increases in Pdyn were shown to drive
sudden impulses (SIs) in the geomagnetic field. While many of these SIs
appear coincident with CNA, SIs without CNA were also observed. During this
period, the threshold of geomagnetic activity required for SC driven
precipitation was exceeded. This implies that solar wind density driven SIs
occurring during storm recovery can drive a different response in particle
precipitation to typical SCs. |
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