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| Titel |
EISCAT observations of plasma patches at sub-auroral cusp latitudes |
| VerfasserIn |
J. Moen, H. C. Carlson, K. Oksavik, C. P. Nielsen, S. E. Pryse, H. R. Middleton, I. W. McCrea, P. Gallop |
| 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 ; 24, no. 9 ; Nr. 24, no. 9 (2006-09-20), S.2363-2374 |
| Datensatznummer |
250015632
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| Publikation (Nr.) |
 copernicus.org/angeo-24-2363-2006.pdf |
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| Zusammenfassung |
| A sequence of 3 patches of high-density (1012 m−3) cold plasma on
a horizontal scale-size of 300–700 km was observed near magnetic noon by the
EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a
trajectory towards the cusp inflow region. The combination of radar and
all-sky observations demonstrates that the patches must have been segmented
equatorward of the cusp/cleft auroral display, and hence their properties
had not yet been influenced by cusp particle showers and electrodynamics on
open flux tubes. The last patch in the sequence was intersected by radio
tomography observations, and was found to be located adjacent to a broader
region of the same high electron density further south. The patches occurred
under moderately active conditions (Kp=3) and the total electron content
(TEC) of the high-density plasma was 45 TEC units. The train of patches
appeared as a segmentation of the tongue of ionization. The sequence of
patches occurred in association with a sequence of flow bursts in the dusk
cell return flow. It is proposed that reconnection driven pulsed convection
is able to create sub-auroral patches in the region where high density
mid-latitude plasma is diverted poleward toward the cusp. It is the downward
Birkeland current sheet located at the equatorward boundary of the flow
disturbance that represents the actual cutting mechanism. |
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