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Solar cycle and geomagnetic N +1 /O +1 variation in outer dayside magnetosphere: Possible relation to topside ionosphere
Author(s) -
Christon S. P.,
Mall U.,
Eastman T. E.,
Gloeckler G.,
Lui A. T. Y.,
McEntire R. W.,
Roelof E. C.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013988
Subject(s) - ionosphere , ring current , geomagnetic storm , physics , magnetosphere , solar minimum , solar maximum , earth's magnetic field , ion , solar cycle , atmospheric sciences , solar cycle 22 , astrophysics , geophysics , solar wind , magnetic field , plasma , nuclear physics , quantum mechanics
O +1 and N +1 are important ring current ions in great magnetic storms. We study ∼10–210 keV/e O +1 and N +1 in dayside outer ring current (ORC) at ∼9–15 R E using Geotail's EPIC/STICS ion spectrometer. We find: average N +1 /O +1 (Γ N/O ) varies by ∼2 over a solar cycle, ∼40% (∼20%) at solar minimum (maximum); individual Γ N/O values range from ∼0.15 (moderate solar maximum storm) to ∼1 (18‐hr solar minimum superquiet interval); and N +1 is third in importance after H + and O +1 during two moderate storms (Dst min ∼ −80 nT, ∼25% great storm intensity), one at minimum, one maximum. High‐latitude topside ionospheric AE‐D/MIMS ion composition data form a baseline reference used to argue that ORC Γ N/O variations generally reflect and may be partially explained by topside ionospheric density Γ N/O spatial variations.