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| Titel |
E-region echo characteristics governed by auroral arc electrodynamics |
| VerfasserIn |
S. E. Milan, N. Sato, Mark Lester, Y. Murata, Y. Shinkai, H. Doi, H. U. Frey, T. Saemundsson |
| 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 ; 21, no. 7 ; Nr. 21, no. 7, S.1567-1575 |
| Datensatznummer |
250014663
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| Publikation (Nr.) |
 copernicus.org/angeo-21-1567-2003.pdf |
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| Zusammenfassung |
Observations of a pair of
auroral arc features by two imagers, one ground- and one space-based, allows
the associated field-aligned current (FAC) and electric field structure to be
inferred. Simultaneous observations of HF radar echoes provide an insight into
the irregularity-generating mechanisms. This is especially interesting for the
E-region echoes observed, which form the focus of our analysis, and from which
several conclusions can be drawn, summarized as follows. Latitudinal variations
in echo characteristics are governed by the FAC and electric field background.
Particularly sharp boundaries are found at the edges of auroral arcs. Within
regions of auroral luminosity, echoes have Doppler shifts below the
ion-acoustic speed and are proportional to the electric field, suggesting
scatter from gradient drift waves. Regions of downward FAC are associated with
mixed high and low Doppler shift echoes. The high Doppler shift component is
greatly in excess of the ion-acoustic speed, but seems to be commensurate with
the driving electric field. The low Doppler shift component appears to be much
depressed below expectations.
Key words. Ionosphere (ionospheric
irregularities; electric fields and currents) |
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