Spatial distribution of upstream magnetospheric ≥50 keV ions
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 even...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2000-01-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/18/42/2000/angeo-18-42-2000.pdf |
| _version_ | 1818964807284424704 |
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| author | G. C. Anagnostopoulos G. C. Anagnostopoulos G. Argyropoulos G. Argyropoulos G. Kaliabetsos G. Kaliabetsos |
| author_facet | G. C. Anagnostopoulos G. C. Anagnostopoulos G. Argyropoulos G. Argyropoulos G. Kaliabetsos G. Kaliabetsos |
| author_sort | G. C. Anagnostopoulos |
| collection | DOAJ |
| description | 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 <i>Kp</i>, with an average
solar wind speed as high as 620 km s<sup>-1</sup> and values of the index <i>Kp </i>>
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.<br><br><b>Key words. </b>Interplanetary physics (energetic particles;
planetary bow shocks) |
| first_indexed | 2024-12-20T13:06:59Z |
| format | Article |
| id | doaj.art-05bce62b0c2545f2beed3fd98cdf5b30 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-20T13:06:59Z |
| publishDate | 2000-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-05bce62b0c2545f2beed3fd98cdf5b302022-12-21T19:39:46ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762000-01-0118424610.1007/s00585-000-0042-xSpatial distribution of upstream magnetospheric ≥50 keV ionsG. C. Anagnostopoulos0G. C. Anagnostopoulos1G. Argyropoulos2G. Argyropoulos3G. Kaliabetsos4G. Kaliabetsos5E-mail: anagnosto@xanthi.cc.duth.grDepartment of Electrical and Computer Engineering, University of Thrace, Xanthi 67100, GreeceE-mail: anagnosto@xanthi.cc.duth.grDepartment of Electrical and Computer Engineering, University of Thrace, Xanthi 67100, GreeceE-mail: anagnosto@xanthi.cc.duth.grDepartment of Electrical and Computer Engineering, University of Thrace, Xanthi 67100, GreeceWe 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 <i>Kp</i>, with an average solar wind speed as high as 620 km s<sup>-1</sup> and values of the index <i>Kp </i>> 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.<br><br><b>Key words. </b>Interplanetary physics (energetic particles; planetary bow shocks)https://www.ann-geophys.net/18/42/2000/angeo-18-42-2000.pdf |
| spellingShingle | G. C. Anagnostopoulos G. C. Anagnostopoulos G. Argyropoulos G. Argyropoulos G. Kaliabetsos G. Kaliabetsos Spatial distribution of upstream magnetospheric ≥50 keV ions Annales Geophysicae |
| title | Spatial distribution of upstream magnetospheric ≥50 keV ions |
| title_full | Spatial distribution of upstream magnetospheric ≥50 keV ions |
| title_fullStr | Spatial distribution of upstream magnetospheric ≥50 keV ions |
| title_full_unstemmed | Spatial distribution of upstream magnetospheric ≥50 keV ions |
| title_short | Spatial distribution of upstream magnetospheric ≥50 keV ions |
| title_sort | spatial distribution of upstream magnetospheric x2265 50 kev ions |
| url | https://www.ann-geophys.net/18/42/2000/angeo-18-42-2000.pdf |
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