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| Titel |
Storm-time ring current: model-dependent results |
| VerfasserIn |
N. Yu. Ganushkina, M. W. Liemohn, T. I. Pulkkinen |
| 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 (2012-01-17), S.177-202 |
| Datensatznummer |
250017173
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| Publikation (Nr.) |
 copernicus.org/angeo-30-177-2012.pdf |
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| Zusammenfassung |
| The main point of the paper is to investigate how much the modeled ring current
depends on the representations of magnetic and electric fields and boundary
conditions used in simulations. Two storm events, one moderate (SymH minimum
of −120 nT) on 6–7 November 1997 and one intense (SymH minimum of −230 nT) on
21–22 October 1999, are modeled. A rather simple ring current model is
employed, namely, the Inner Magnetosphere Particle Transport and Acceleration
model (IMPTAM), in order to make the results most evident. Four different
magnetic field and two electric field representations and four boundary
conditions are used. We find that different combinations of the magnetic and
electric field configurations and boundary conditions result in very different
modeled ring current, and, therefore, the physical conclusions based on
simulation results can differ significantly. A time-dependent boundary outside
of 6.6 RE gives a possibility to take into account the particles in the
transition region (between dipole and stretched field lines) forming partial
ring current and near-Earth tail current in that region. Calculating the model
SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke
(DPS) relation gives larger and more realistic values, since the currents are
calculated in the regions with nondipolar magnetic field. Therefore, the
boundary location and the method of SymH* calculation are of key importance
for ring current data-model comparisons to be correctly interpreted. |
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