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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, Johan De Keyser |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089915
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| Publikation (Nr.) |
 EGU/EGU2014-4128.pdf |
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| Zusammenfassung |
| In a recently published work, we studied the relations between the position of the
plasmapause and the position of the radiation belt boundaries. The Cluster mission offers the
exceptional opportunity to analyze those different regions of the inner magnetosphere with
identical sensors on multiple spacecraft. We compare the positions of the radiation
belt edges deduced from CIS observations (electrons with energy > 2 MeV) with
the positions of the plasmapause derived from WHISPER data (electron plasma
frequency). In addition, we compare those results with the noundaries positions
determined from RAPID observations (electrons with energy between 244.1 and 406.5
keV).
The period of 1 April 2007 to 31 March 2009 has been chosen for the analysis because at that
time Cluster’s perigee was located at lower radial distances than during the earlier part of the
mission (as close as 2 RE, deep inside the plasmasphere and the radiation belts). This time
period corresponds to a long solar activity minimum.
Differences are observed between the radiation belt boundary positions obtained
from the two different instruments: The radiation belt positions are related to the
energy bands. The plasmapause position is more variable than the radiation belt
boundary positions, 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 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.
We have pursued the analysis of radiation belt boundaries positions during time period with
higher geomagnetic activity, showing different characteristics. We present also some first
conclusions from a comparison of those data with a global plasmasphere model and a
radiation belt model. |
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