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| Titel |
Seasonal variation of upstream energetic electrons as observed by COSTEP/SOHO |
| VerfasserIn |
A. Klassen, R. Gómez-Herrero, R. Müller-Mellin, B. Heber |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250027910
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| Zusammenfassung |
| We have analyzed 219 electron bursts at energies above 0.25 MeV observed with the
EPHIN/COSTEP instrument onboard the SOHO spacecraft far upstream of the Earth’s
bow–shock at the libration point L1 from 1996 through 2008. Most of the bursts were
observed during low solar activity (in 1996–1997 and in 2005–2008) and all 219 bursts were
not associated with solar particle events. It is shown that some upstream events are detected at
energies above 0.7 MeV.
We find that the event occurrence number shows a distinct seasonal variation with
maxima around equinoxes and minima near solstices. This together with a close
correspondence between the event occurrence number with maxima in solar wind speed
(V sw), geomagnetic activity index (Ap) and in the southward interplanetary magnetic field
(IMF) component (Bz) indicates that the observed events can be explained in terms of
leakage of magnetospheric particles during enhanced geoactivity rather than by acceleration
at the Earth’s bow–shock. |
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