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| Titel |
Links between the plasmapause and the radiation belts boundaries as observed by the instruments CIS, RAPID and WHISPER onboard Cluster |
| VerfasserIn |
Fabien Darrouzet, Viviane Pierrard, Sylvie Benck, Guillaume Lointier, Juan Cabrera, Kris Borremans, Natalia Ganushkina |
| 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 |
250073387
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| Zusammenfassung |
| In the present work, we study the relations between the position of the plasmapause and the
position of the radiation belts boundaries. The Cluster mission gives the exceptional
opportunity to analyze with the same spacecraft those different regions of the inner
magnetosphere. We compare the positions of the radiation belts edges deduced from CIS
observations (electrons with energy > 2 MeV) taken onboard Cluster with the positions of the
plasmapause derived from WHISPER data (electron plasma frequency) measured
onboard Cluster. In addition, we compare those results with the edges positions
determined from RAPID observations (electrons with energy between 244.1 and
406.5 keV) taken onboard Cluster. The period of 1 April 2007 to 31 March 2009
has been chosen for the analysis because at that time Cluster was located at lower
radial distances than during the earlier part of the mission. The perigee was then
as close as 2 RE, deep inside the plasmasphere and the radiation belts. This time
period corresponds to a long solar minimum activity. Differences are observed
between the two datasets of radiation belt boundaries positions obtained from the two
different instruments: The radiation belt positions are related to the energy bands. The
results show that the plasmapause is more variable than the radiation belt boundaries,
especially during small geomagnetic activity enhancements. A correspondence
is observed between the plasmapause position determined by WHISPER and the
outer edge of the outer radiation belt of energetic electrons (> 2 MeV) observed by
CIS. This result is unexpected since previous studies based on other spacecraft
observations indicated more a correlation between the inner edge of the outer belt and the
plasmapause. However, during higher geomagnetic activity time periods, the plasmapause is
located closer to the inner boundary of the outer radiation belt. Also, the thickness of
the slot region is found to follow the global evolution of the geomagnetic activity. |
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