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Energetic O+ and H+ Ions in the Plasma Sheet: Implications for the Transport of Ionospheric IonsThe present study statistically examines the characteristics of energetic ions in the plasma sheet using the Geotail/Energetic Particle and Ion Composition data. An emphasis is placed on the O+ ions, and the characteristics of the H+ ions are used as references. The following is a summary of the results. (1) The average O+ energy is lower during solar maximum and higher during solar minimum. A similar tendency is also found for the average H+ energy, but only for geomagnetically active times; (2) The O+ -to -H+ ratios of number and energy densities are several times higher during solar maximum than during solar minimum; (3) The average H+ and O+ energies and the O+ -to -H+ ratios of number and energy densities all increase with geomagnetic activity. The differences among different solar phases not only persist but also increase with increasing geomagnetic activity; (4) Whereas the average H+ energy increases toward Earth, the average O+ energy decreases toward Earth. The average energy increases toward dusk for both the H+ and O+ ions; (5) The O+ -to -H+ ratios of number and energy densities increase toward Earth during all solar phases, but most clearly during solar maximum. These results suggest that the solar illumination enhances the ionospheric outflow more effectively with increasing geomagnetic activity and that a significant portion of the O+ ions is transported directly from the ionosphere to the near ]Earth region rather than through the distant tail.
Document ID
20120007917
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ohtani, S.
(Johns Hopkins Univ. Laurel, MD, United States)
Nose, M.
(Kyoto Univ. Kyoto, Japan)
Christon, S. P.
(Focused Analysis and Research Columbia, MD, United States)
Lui, A. T.
(Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
August 25, 2013
Publication Date
October 14, 2011
Publication Information
Publication: Journal of Geophysical Research
Volume: 116
Subject Category
Geophysics
Funding Number(s)
CONTRACT_GRANT: NNX08AM50G
CONTRACT_GRANT: NNX09AF46G
Distribution Limits
Public
Copyright
Other

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