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| Titel |
Multi-instrument ground-based observations of a travelling convection vortices event |
| VerfasserIn |
H. Lühr, M. Lockwood, P. E. Sandholt, T. L. Hansen, T. Moretto |
| 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 ; 14, no. 2 ; Nr. 14, no. 2, S.162-181 |
| Datensatznummer |
250012166
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| Publikation (Nr.) |
 copernicus.org/angeo-14-162-1996.pdf |
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| Zusammenfassung |
| A coordinated ground-based observational
campaign using the IMAGE magnetometer network, EISCAT radars and optical
instruments on Svalbard has made possible detailed studies of a travelling
convection vortices (TCV) event on 6 January 1992. Combining the data from these
facilities allows us to draw a very detailed picture of the features and
dynamics of this TCV event. On the way from the noon to the drawn meridian, the
vortices went through a remarkable development. The propagation velocity in the
ionosphere increased from 2.5 to 7.4 km s–1, and the orientation of
the major axes of the vortices rotated from being almost parallel to the
magnetic meridian near noon to essentially perpendicular at dawn. By combining
electric fields obtained by EISCAT and ionospheric currents deduced from
magnetic field recordings, conductivities associated with the vortices could be
estimated. Contrary to expectations we found higher conductivities below the
downward field aligned current (FAC) filament than below the upward directed.
Unexpected results also emerged from the optical observations. For most of the
time there were no discrete aurora at 557.7 nm associated with the TCVs. Only
once did a discrete form appear at the foot of the upward FAC. This aurora
subsequently expanded eastward and westward leaving its centre at the same
longitude while the TCV continued to travel westward. Also we try to identify
the source regions of TCVs in the magnetosphere and discuss possible generation
mechanisms. |
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