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| Titel |
Case studies on the dynamics of Pi3 geomagnetic and riometer pulsations during auroral activations |
| VerfasserIn |
N. G. Kleimenova, O. V. Kozyreva, K. Kauristie, J. Manninen, A. Ranta |
| 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 ; 20, no. 2 ; Nr. 20, no. 2, S.151-159 |
| Datensatznummer |
250014351
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| Publikation (Nr.) |
 copernicus.org/angeo-20-151-2002.pdf |
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| Zusammenfassung |
A sequence of three
subsequent auroral activations (at 18:10, 19:48 and 20:00 UT) on 9 February
1997 is analysed. The brightenings of optical auroras were collocated with
latitudinally localized bursts of pulsating riometer absorption and Pi3
geomagnetic pulsations. In two of the cases, the strongest westward directed
electrojet currents and the footpoint of the upward directed field-aligned
currents related to the auroral brightening were observed in the same region as
the largest amplitude of the pulsations and their polarization changed. In the
third case, field-aligned current signatures were present, but not so
pronounced that their accurate location could not be defined. In all cases, the
spectra of geomagnetic and absorption pulsations were similar. Based on
ground-based observations alone, it is difficult to say whether the energetic
particle precipitation (riometer absorption) was modulated by the geomagnetic
pulsations or whether the geomagnetic pulsations were caused by varying
ionospheric currents controlled by the precipitating particle intensity.
However, the localized nature of both pulsations of the two different phenomena
and their tight coupling with each other seem to support the latter option.
Key words. Ionosphere (Particle
precipitation) – Magnetospheric physics (auroral phenomena; MHD waves and
instabilities) |
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