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| Titel |
Distortions of the magnetic field by storm-time current systems in Earth's magnetosphere |
| VerfasserIn |
N. Yu. Ganushkina, M. W. Liemohn, M. V. Kubyshkina, R. Ilie, H. J. Singer |
| 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 ; 28, no. 1 ; Nr. 28, no. 1 (2010-01-18), S.123-140 |
| Datensatznummer |
250016748
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| Publikation (Nr.) |
 copernicus.org/angeo-28-123-2010.pdf |
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| Zusammenfassung |
| Magnetic field and current system changes in Earth's inner magnetosphere
during storm times are studied using two principally different modeling
approaches: on one hand, the event-oriented empirical magnetic field model,
and, on the other, the Space Weather Modeling Framework (SWMF) built around a
global MHD simulation. Two storm events, one moderate storm on 6–7 November
1997 with Dst minimum about −120 nT and one intense storm on 21–23 October
1999 with Dst minimum about −250 nT were modeled. Both modeling approaches
predicted a large ring current (first partial, later symmetric) contribution
to the magnetic field perturbation for the intense storm. For the moderate
storm, the tail current plays a dominant role in the event-oriented model
results, while the SWMF results showed no strong tail current in the main
phase, which resulted in a poorly timed storm peak relative to the
observations. These results imply that the the development of a ring current
depends on a strong force to inject the particles deep into the inner
magnetosphere, and that the tail current is an important external source for
the distortions of the inner magnetospheric magnetic field for both storms.
Neither modeling approach was able to reproduce all the variations in the
Bx and By components observed at geostationary orbit by GOES satellites
during these two storms: the magnetopause current intensifications are
inadequate, and the field-aligned currents are not sufficiently represented.
While the event-oriented model reproduces rather well the Bz component at
geostationary orbit, including the substorm-associated changes, the SWMF
field is too dipolar at these locations. The empirical model is a useful tool
for validation of the first-principle based models such as the SWMF. |
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