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| Titel |
Evidence for solar-production as a source of polar-cap plasma |
| VerfasserIn |
S. E. Pryse, R. W. Sims, J. Moen, L. Kersley, D. Lorentzen, W. F. Denig |
| 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 ; 22, no. 4 ; Nr. 22, no. 4 (2004-04-02), S.1093-1102 |
| Datensatznummer |
250014825
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| Publikation (Nr.) |
 copernicus.org/angeo-22-1093-2004.pdf |
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| Zusammenfassung |
The focus of the study is a region of enhanced ionospheric densities observed by the
EISCAT Svalbard radar in the polar F-region near local magnetic noon under conditions
of IMF Bz<0. Multi-instrument observations, using optical, spacecraft and radar
instrumentation, together with radio tomographic imaging, have been used to identify the
source of the enhancement and establish the background ionospheric conditions.
Soft-particle precipitation was ruled out as a candidate for the production. Tomographic
observations identified a latitudinally restricted region of enhanced densities at sub-auroral
latitudes, distinct from the normal mid-latitude ionosphere, which was likely to be
the source. The evidence suggested that the increased sub-auroral densities were
photoionisation produced at the equatorward edge of the afternoon high-latitude cell,
where the plasma is exposed to sunlight for an extended period as it flows slowly
sunward toward magnetic noon. It is proposed that this plasma, once in the noon
sector,
was drawn antisunward by the high-latitude convection toward polar latitudes where it
was identified by the EISCAT Svalbard radar. The observations are discussed in terms of
earlier modelling studies of polar patch densities.
Key words. Ionosphere (polar ionosphere; plasma temerature;
plasma convection) |
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