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| Titel |
Outflowing ionospheric oxygen-ion motion in a reconfigurating magnetosphere |
| VerfasserIn |
E. B. Wodnicka, M. Banaszkiewicz |
| 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 ; 15, no. 1 ; Nr. 15, no. 1, S.5-16 |
| Datensatznummer |
250012568
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| Publikation (Nr.) |
 copernicus.org/angeo-15-5-1997.pdf |
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| Zusammenfassung |
| During substorms, large-scale changes of the
topology of the Earth's magnetosphere following the variation of the
characteristics of the interplanetary medium are accompanied by the induction of
the electric field. In this study a model of a time-dependent magnetosphere is
constructed and the large-scale features of the induced electric field are
described. Local-time sectors with upward or downward field-aligned component
and with intense perpendicular component of the electric field are
distinguished. The electric-field structure implies the existence of outflow
regions particularly effective in ion energization. With the vector potential
adopted in the study, the region from which the most energized ions originate is
defined by the local-time sector near 2100 MLT and latitude zone near 71°
MLAT. The motion of ionospheric oxygen ions of energy 0.3–3 keV is investigated
during a 5-min reconfiguration event when the tail-like magnetospheric field
relaxes to the dipole-like field. As the characteristics of plasma in the
regions near the equatorial plane affect the substorm evolution, the energy,
pitch angle, and the magnetic moment of ions in these regions are analyzed.
These quantities depend on the initial energy and pitch angle of the ion and on
the magnetic and electric field it encounters on its way. With the vector
potential adopted, the energy attained in the equatorial regions can reach
hundreds of keV. Three regimes of magnetic-moment changes are identified:
adiabatic, oscillating, and monotonous, depending on the ion initial energy and
pitch angle and on the magnetic- and electric-field spatial and temporal scales.
The implications for the global substorm dynamics are discussed |
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