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| Titel |
Spatial distribution of upstream magnetospheric ≥50 keV ions |
| VerfasserIn |
G. C. Anagnostopoulos, G. Argyropoulos, G. Kaliabetsos |
| 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 ; 18, no. 1 ; Nr. 18, no. 1, S.42-46 |
| Datensatznummer |
250013879
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| Publikation (Nr.) |
 copernicus.org/angeo-18-42-2000.pdf |
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| Zusammenfassung |
We present for the first time a statistical
study of \geq50 keV ion events of a magnetospheric origin upstream from Earth's
bow shock. The statistical analysis of the 50-220 keV ion events observed by the
IMP-8 spacecraft shows: (1) a dawn-dusk asymmetry in ion distributions, with
most events and lower intensities upstream from the quasi-parallel pre-dawn side
(4 LT-6 LT) of the bow shock, (2) highest ion fluxes upstream from the nose/dusk
side of the bow shock under an almost radial interplanetary magnetic field (IMF)
configuration, and (3) a positive correlation of the ion intensities with the
solar wind speed and the index of geomagnetic index Kp, with an average
solar wind speed as high as 620 km s-1 and values of the index Kp >
2. The statistical results are consistent with (1) preferential leakage of
~50 keV magnetospheric ions from the dusk magnetopause, (2) nearly scatter
free motion of ~50 keV ions within the magnetosheath, and (3) final escape of
magnetospheric ions from the quasi-parallel dawn side of the bow shock. An
additional statistical analysis of higher energy (290-500 keV) upstream ion
events also shows a dawn-dusk asymmetry in the occurrence frequency of these
events, with the occurrence frequency ranging between ~16%-~34% in the
upstream region.
Key words. Interplanetary physics (energetic particles;
planetary bow shocks) |
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