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| Titel |
The high altitude stagnation region as a second source of cold ion outflow |
| VerfasserIn |
Kun Li, Stein Haaland, Patrick Daly, Mats André, Anders Eriksson |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111647
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| Publikation (Nr.) |
 EGU/EGU2015-11788.pdf |
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| Zusammenfassung |
| The Earth’s magnetospheric plasma is believed to be significantly contributed by the
ionospheric outflow. Ions with low energies traveling along the magnetic field lines are
transported tailward due to the magnetospheric large scale convection driven by the dayside
reconnection. In this paper, we use ten years data set of cold ion (total energy less than 70 eV)
from two Cluster spacecraft and time shifted measurements of the solar wind to calculate the
trajectories of the cold ions and to determine their source. We suggest that, the ion
outflow from the ionosphere could be stagnated at high altitude cusp region, 2~8
Earth radii (Re) from the center of the Earth. In terms of number of observations,
tailward flow from this region supplies ~9% of the cold ions from the ionosphere. The
cold ions in this region are found to be stagnated, i.e. their parallel velocities were
zero because of gravitational drag. While the convection at high altitudes is higher
enough to contribute the centrifugal acceleration, those cold ions start to move
tailward and are observed by Cluster in the magnetotail. This outflow shows clear
asymmetries for dawnward and duskward Interplanetary Magnetic Field (IMF). |
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