Responses of the thermosphere and ionosphere system to concurrent solar flares and geomagnetic storms

We found that E -region electron density response to the flares was much smaller inside the auroral oval than it was outside the auroral oval due to an extra source of ionization by auroral particle precipitation.

During quiet times in this period, flare enhanced ionization, which decreased daytime eastward electric fields, caused an initial weakening of the vertical E × B drifts. This weakening of the vertical E × B drifts was on the order of ~20% for an X8.2 flare in this period. During storm times, flare-induced initial changes of the vertical plasma drifts varied between being positive and being negative, depending on latitudes, due to storm-time disturbance dynamo effects.