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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 |
Hui Wang, Hermann Luehr, Aaron Ridley |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054101
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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
(21:00-22:00MLT) at 70o-72o 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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