Open AccessInfluence of ionosphere conductivity on the ring current
Author(s) -
Ebihara Y.,
Fok M.C.,
Wolf R. A.,
Immel T. J.,
Moore T. E.
Publication year - 2004
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2003ja010351
Subject(s) - ring current , solstice , ionosphere , physics , atmospheric sciences , magnetosphere , solar wind , electron precipitation , geophysics , current (fluid) , equinox , computational physics , astronomy , magnetic field , latitude , quantum mechanics , thermodynamics
Using the Comprehensive Ring Current Model (CRCM), which self‐consistently solves the kinetic equation of ring current protons and the closure of the electric current between the magnetosphere and ionosphere, we have studied how different changes in the ionospheric conductivity affect the strength of the ring current. The conductivity for F10.7 = 250 × 10 4 Janskys (Jy) (solar maximum condition) results in a ring current that is about 29% stronger than for F10.7 = 70 × 10 4 Jy (solar minimum condition). The conductivity at equinox results in a ring current that is about 5% stronger than at solstice because the two‐hemisphere height‐integrated conductivities at equinox are higher than at solstice. This would be a new mechanism for explaining the semiannual variation of Dst . Simulation with a realistic auroral conductivity estimated from the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE)/Far Ultraviolet Imager (FUV) auroral imager data reveals the fact that auroral brightenings do not significantly change the intensity of the ring current. The overshielding condition is found to be produced when the auroral conductivity decreases abruptly near the Dst minimum, triggering a rapid decay of the ring current. The ring current is shown to be influenced not only by the interplanetary magnetic field and the solar wind but also by solar radiation and morphological features of the auroral electron precipitation as well.