Disturbed Ionospheric Electrodynamics (Invited)

The dynamics and electrodynamics of the global thermosphere-ionosphere system can be strongly affected by magnetospheric disturbances. High-latitude electric fields and currents penetrate almost instantaneously to middle and low latitudes, but are modulated by electrodynamic interaction with the magnetospheric plasma. In addition, the energy and momentum inputs at high latitudes can alter the global thermospheric winds, and thereby also affect the ionospheric-dynamo generation of fields and currents. The resultant global electric fields and currents depend on the distribution of ionospheric conductivity, which itself can become significantly perturbed by the electric field, the wind, and energetic particle precipitation from the magnetosphere. Models of disturbed ionospheric electrodynamics need to account for the mutual coupling with magnetospheric plasma, the disturbances of the thermospheric wind, and the changes in ionospheric conductivity. This presentation reviews the modeling of these processes, in relation to observations, in order to identify the importance of the different elements in producing disturbances of ionospheric electrodynamics.