Local Time Response of Auroral Electrojet During Magnetically Disturbed Periods: DMSP and CHAMP Coordinated Observations

Abstract

AbstractBased on 10 years of Defense Meteorological Satellite Program and Challenging Minisatellite Payload coordinated observations, we investigated the local time variation in the response time and strength of the auroral electrojet (AEJ) with respect to the sudden change in solar wind inputs, including merging electric field (Em), substorm, and interplanetary (IP) shock. The daytime (nighttime) AEJ responded several minutes (>30 min) after the key time of Em enhancement. For substorms and IP shocks, the AEJ at all local times showed an instantaneous response. The local time with a westward enhancement of the AEJ was wider during substorms than those during Em enhancement and IP shock. The times when the AEJ or disturbance AEJ attained peaks varied for different disturbances. At IP shock onset, the AEJ in the prenoon and postnoon increased in opposite directions to that in the quiet time. During Em enhancement and IP shock, the duskside AEJ attained a peak faster than the dawnside owing to the more rapid change in the duskside Hall conductance. The relative effects of the convection electric field and Hall conductance on the disturbance AEJ are disclosed at different local times. This study offers insights into the physical mechanisms of local time differences in the response time and strength of AEJ during disturbed periods.