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| Titel |
Plasma convection jets near the poleward boundary of the nightside auroral oval and their relation to Pedersen conductivity gradients |
| VerfasserIn |
H. Wang, H. Lühr, A. J. Ridley |
| 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 ; 28, no. 4 ; Nr. 28, no. 4 (2010-04-15), S.969-976 |
| Datensatznummer |
250016818
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| Publikation (Nr.) |
 copernicus.org/angeo-28-969-2010.pdf |
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| Zusammenfassung |
| In this work, we have shown that the ionospheric azimuthal plasma
velocity jets near the open-closed field line boundary on the
nightside can be associated with the peak in the ionospheric
conductivity gradient. Both model and DMSP observations have been
utilized to conduct this investigation. The model tests show that
when the gradient of conductivity in the poleward boundary becomes
sharper, convection peaks appear around the poleward edge of the
aurora. The model results have been confirmed by DMSP
observations. Hundreds of large ion flow events are identified
from one year DMSP observations, with flow speed larger than 500 m/s
that occurred poleward of the aurora. Among them, 280 (74%)
events are found to be associated with conductivity gradient
peaks. Most of the convection jets occur in winter when
conductivity gradients are expected to be large. The convection
jets tend to occur at later local times (21:00–22:00 MLT) at
70°–72° MLat. These events are preceded by
increasing of the merging electric field suggesting that they
occur after the expansion of the polar cap. Both observation and
model results show that the conductivity gradient at the polar cap
boundary are one of the important elements in establishing the
convection jets. |
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