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Global ENA observations of the storm mainphase ring current: Implications for skewed electric fields in the inner magnetosphere
Author(s) -
Cson Brandt P.,
Ohtani S.,
Mitchell D. G.,
Fok M.C.,
Roelof E. C.,
Demajistre R.
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 - 10.1029/2002gl015160
Subject(s) - ring current , magnetosphere , physics , van allen probes , geomagnetic storm , solar wind , geophysics , interplanetary spaceflight , electric field , energetic neutral atom , computational physics , storm , interplanetary magnetic field , magnetic field , van allen radiation belt , meteorology , electron , nuclear physics , quantum mechanics
The local time distribution of the ring current in the 27–119 keV range during several geomagnetic storm main phases have been investigated. The data was obtained by the high energy neutral atom (HENA) imager onboard IMAGE. Global proton distributions are derived from the observed energetic neutral atom (ENA) images using a linear inversion technique. During storms with low IMF B y the peak of the proton distribution is around 01 MLT. For storms with high IMF B y the peak can rotate to dawn. The rotation angle depends on solar wind velocity and interplanetary magnetic field (IMF) B y , but less on IMF B z . We discuss how this morphology implies the existence of strong and skewed equatorial electric fields in the inner magnetosphere. Our results are consistent with in‐situ ring current measurements, radar observations and with kinetic models that self‐consistently calculate the electric field produced by the closure of the partial ring current.