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| Titel |
Storm time dynamics of auroral electrojets: CHAMP observation and the Space Weather Modeling Framework comparison |
| VerfasserIn |
H. Wang, H. Lühr, A. Ridley, P. Ritter, Y. Yu |
| 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. 3 ; Nr. 26, no. 3 (2008-03-26), S.555-570 |
| Datensatznummer |
250016044
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| Publikation (Nr.) |
 copernicus.org/angeo-26-555-2008.pdf |
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| Zusammenfassung |
| We investigate variations of the location and intensity of auroral
currents during two magnetic storm periods based on magnetic field
measurements from CHAMP separately for both hemispheres, as well
as for the dayside and nightside. The corresponding auroral
electrojet current densities are on average enhanced by about a
factor of 7 compared to the quiet time current strengths. The
nightside westward current densities are on average 1.8 (2.2)
times larger than the dayside eastward current densities in the
Northern (Southern) Hemisphere. Both eastward and westward
currents are present during the storm periods with the most
intense electrojets appearing during the main phase of the storm,
before the ring current maximizes in strength. The eastward and
westward electrojet centers can expand to 55° MLat during
intense storms, as is observed on 31 March 2001 with Dst=−387 nT.
The equatorward shift of auroral currents on the dayside
is closely controlled by the southward IMF, while the latitudinal
variations on the nightside are better described by the variations
of the Dst index. However, the equatorward and poleward
motion of the nightside auroral currents occur earlier than the
Dst variations. The Space Weather Modeling Framework (SWMF)
can capture the general dynamics of the storm time current
variations. Both the model and the actual data show that the
currents tend to saturate when the merging electric field is
larger than 10 mV/m. However, the exact prediction of the temporal
development of the currents is still not satisfactory. |
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