Ionospheric electric field variations during a geomagnetic storm simulated by a coupled magnetosphere ionosphere thermosphere (CMIT) model

摘要

A coupled magnetosphere ionosphere thermosphere (CMIT 2.0) model has been developed. It is capable of self-consistently calculating global ionospheric electric fields that include the imposed magnetospheric convection field, neutral wind dynamo and penetration electric fields. The CMIT 2.0 simulated ionospheric F-2 region ion vertical drift velocities at the magnetic equator were compared with those measured by ground-based instruments during the April 2 5, 2004, storm. CMIT 2.0 captured the temporal variations seen in the measurements during both the quiet and active periods. These temporal variations corresponded mainly to the variations in the high latitude electric fields driven by changes in solar wind conditions. CMIT 2.0, however, overestimated the magnitudes of the variations of the vertical drifts. In addition, CMIT 2.0 simulated the observed pre-reversal enhancement well. This enhancement was driven mostly by the neutral wind dynamo.