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| Titel |
Properties and origin of energetic particles at the duskside of the Earth's magnetosheath throughout a great storm |
| VerfasserIn |
D. V. Sarafopoulos, M. A. Athanasiu, E. T. Sarris, T. Yamamoto, S. Kokubun |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 17, no. 9 ; Nr. 17, no. 9, S.1121-1133 |
| Datensatznummer |
250013805
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| Publikation (Nr.) |
 copernicus.org/angeo-17-1121-1999.pdf |
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| Zusammenfassung |
We study an interval of 56 h on January 16 to
18, 1995, during which the GEOTAIL spacecraft traversed the duskside
magnetosheath from
X @ -15 to -40 RE and the EPIC/ICS
and EPIC/STICS sensors sporadically detected tens of energetic particle bursts.
This interval coincides with the expansion and growth of a great geomagnetic
storm. The flux bursts are strongly dependent on the magnetic field orientation.
They switch on whenever the Bz component approaches zero (Bz
@ 0 nT). We strongly suggest a
magnetospheric origin for the energetic ions and electrons streaming along these
"exodus channels". The time profiles for energetic protons and
"tracer" O+ ions are nearly identical, which suggests a
common source. We suggest that the particles leak out of the magnetosphere all
the time and that when the magnetosheath magnetic field connects the spacecraft
to the magnetotail, they stream away to be observed by the GEOTAIL sensors. The
energetic electron fluxes are not observed as commonly as the ions, indicating
that their source is more limited in extent. In one case study the magnetosheath
magnetic field lines are draped around the magnetopause within the YZ plane and
a dispersed structure for peak fluxes of different species is detected and
interpreted as evidence for energetic electrons leaking out from the dawn LLBL
and then being channelled along the draped magnetic field lines over the
magnetopause. Protons leak from the equatorial dusk LLBL and this spatial
differentiation between electron and proton sources results in the observed
dispersion. A gradient of energetic proton intensities toward the ZGSM
= 0 plane is inferred. There is a permanent layer of energetic particles
adjacent to the magnetosheath during this interval in which the dominant
component of the magnetic field was Bz.
Key words. Magnetospheric physics (magnetosheath;
magnetotail boundary layers; storms and substorms) |
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