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| Titel |
Statistical Analysis of the Electronic Density Distribution in the Plasmasphere using WHISPER/CLUSTER data |
| VerfasserIn |
Guillaume Lointier, Fabien Darrouzet, Pierrette Decreau, Xavier Vallières, Jean-Gabriel Trotignon, Jean-Louis Rauch |
| 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 |
250056771
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| Zusammenfassung |
| The plasmasphere is the innermost region of the magnetosphere. It consists of a dense (102 -
104 cm-3) and cold (1 < eV) plasma of ionospheric source, corotating with Earth and
trapped by closed quasi-dipolar geomagnetic field lines. The plasmasphere can be
seen as the high altitude extension of the low-middle-latitude ionosphere. Its outer
edge, called the plasmapause, is characterized by a sharp density gradient due to the
interplay between the Earth’s rotation and the magnetospheric convection. The
plasmasphere is an active region and plays an important role in the dynamics of the
magnetosphere. It can experience a rapid restructuring in response to geomagnetic
activity increase; in quiet steady conditions, the plasmasphere can refill over few
days.
Characterizing material distributions in the plasmasphere and at the plasmapause
location is of primary importance to study the coupling with others regions of the
magnetosphere. For instance, plasmapause is known to be the site of wave-particle
interaction processes capable of affecting radiation belts and ring current particle
populations.
In this context, the ESA CLUSTER mission offers an excellent opportunity to study the inner
magnetosphere dynamics over a complete solar cycle, due to more than 6000 plasmasphere
crossings near perigee. A systematic analysis of WHISPER plasmaspheric observations is
conducted to describe statistically the spatial distribution of the electronic density, both
globally and at smaller scale (within magnetic flux tubes). One of the objectives is to estimate
the latitudinal dependence of the electronic density along field lines in order to characterize
its variation with respect to geomagnetic locations and dynamic activities. Another
objective is to better understand the erosion phenomena at the plasmapause and to
study the evolution of the density distributions within specific structures, such as
plumes.
We present the method used to elaborate an empirical database of electronic density based on
WHISPER observations, which consists in coupling data to a magnetic model of the
magnetosphere (IGRF-11 + Tsyganenko 2004). From two years of measurements, we
propose a statistical classification of the dynamical state of the magnetosphere (using
geomagnetic indices and interplanetary parameters) in order to discuss the evolution of the
spatial distribution of the electronic density within the plasmasphere and at the
plasmapause. |
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