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| Titel |
Atmospheric and ionospheric outflow from Earth: An update |
| VerfasserIn |
Mats André, Hans Nilsson |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075463
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| Zusammenfassung |
| Non-thermal escape of ions from the upper Terrestrial atmosphere has been observed by
spacecraft and radars for decades. Typical total upflow rates are 1025 to 1026 ions/s, mainly
H+ and O+, varying with solar and magnetospheric magnetic activity. Recent findings show
that the escape, and the plasma in the magnetosphere, often is dominated by low-energy
(below about 10 eV) ions. These ions often cannot be detected onboard sunlit spacecraft,
which often become positively charged to tens of volts. We discuss how a supersonic flow of
low-energy ions cause a wake behind a charged spacecraft and how this can be used to detect
the ions. Using observations by the Cluster spacecraft, putting together observations by
this wake method, and observations by particle detectors, we find that often (more
than 50% of the time) low-energy ions dominate the magnetosphere, while at other
times high-energy (keV) ions dominate. At a given time, ions with low and high
energies may dominate different regions of the magnetosphere. Using observed
electric and magnetic fields, we show that the observed fields are consistent with the
simultaneously observed ions, both for ions with low and with high energies. We
give an update of the importance of low-energy and high-energy ions for the total
upflow and escape of ions from Earth, using observations by Cluster and by other
spacecraft. We briefly compare with ion outflow from Mars observed by Mars Express. |
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