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| Titel |
Statistical dependence of auroral ionospheric currents on solar wind and geomagnetic parameters from 5 years of CHAMP satellite data |
| VerfasserIn |
L. Juusola, K. Kauristie, O. Amm, P. Ritter |
| 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 ; 27, no. 3 ; Nr. 27, no. 3 (2009-03-02), S.1005-1017 |
| Datensatznummer |
250016434
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| Publikation (Nr.) |
 copernicus.org/angeo-27-1005-2009.pdf |
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| Zusammenfassung |
| The effects of the solar wind dynamic pressure (P), the z component of
the solar wind magnetic field (Bz), the merging electric field (Em),
season and the Kp index on R1 and R2 field-aligned currents are studied
statistically using magnetic field data from the CHAMP satellite during
2001–2005. The ionospheric and field-aligned currents are determined from
the magnetic field data by the recently developed 1-D Spherical Elementary
Current System (SECS) method. During southward IMF, increasing |Bz| is
observed to clearly increase the total field-aligned current, while during
northward IMF, the amount of field-aligned current remains fairly constant
regardless of |Bz|. The dependence of the field-aligned current on Bz
is given by |Ir[MA]|=0.054·Bz[nT]2−0.34·Bz[nT]+2.4. With increasing P, the intensity of the
field-aligned current is also found to increase according to
|Ir[MA]|=0.62·P[nPa]+1.6, and the auroral oval is
observed to move equatorward. Increasing Em produces similar behaviour,
described by |Ir[MA]|=1.41·Em[mV/m]+1.4. While the
absolute intensity of the ionospheric current is stronger during negative
than during positive Bz, the relative change in the intensity of the
currents produced by a more intense solar wind dynamic pressure is observed
to be approximately the same regardless of the Bz direction. Increasing
Kp from 0 to ≥5 widens the auroral oval and moves it equatorward from
between 66°–74° AACGM latitude to
59°–71° latitude. The total field aligned current
as a function of Kp is given by |Ir[MA]|=1.1·Kp+0.6.
In agreement with previous studies, total field-aligned current in the summer
is found to be 1.4 times stronger than in the winter. |
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