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| Titel |
In-situ observation of electron kappa distributions associated with discrete auroral arcs |
| VerfasserIn |
Keiichi Ogasawara, George Livadiotis, Marilia Samara, Robert Michell, Guy Grubbs |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125641
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| Publikation (Nr.) |
 EGU/EGU2016-5241.pdf |
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| Zusammenfassung |
| The Medium-energy Electron SPectrometer (MESP) sensor aboard a NASA sounding
rocket was launched from Poker Flat Research Range on 3 March 2014 as a part of
Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment (GREECE) mission.
GREECE targeted to discover convergent E-field structures at low altitude ionosphere to find
their contribution to the rapid fluid-like structures of aurora, and MESP successfully
measured the precipitating electrons from 2 to 200 keV within multiple discrete auroral arcs
with the apogee of 350 km. MESP’s unprecedented electron energy acceptance and high
geometric factor made it possible to investigate precise populations of the suprathermal
components measured in the inverted-V type electron energy distributions. The
feature of these suprathermal electrons are explained by the kappa distribution
functions with the parameters (densty, temperature, and kappa) consistent with
the near-Earth tail plasma sheet, suggesting the source population of the auroral
electrons. The kappa-values are different between each arc observed as a function of
latitude, but are almost stable within one discrete arc. We suggest that this transition of
kappa reflects the probagation history of source electrons through the plasma sheet
by changing its state from non-equilibrium electron distributions to thermal ones. |
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