Electrodynamics of Storm Time Auroral Disturbances

The electrodynamics of magnetic storm-time auroral disturbances is contrasted with the electrodynamics of isolated, classical bulge-type auroral substorms. Global auroral images are used to organize in-situ electrodynamic data from satellites and ground magnetic data from a large array of stations. The distribution of onset locations, the conductance distribution, convection electric field, and the electrojet topology are all analyzed during the development of the main phase magnetic storm. It is found that the onset locations of auroral disturbances are generally later in local time during magnetic storms than for substorms. The convection electrojet throughout the post-midnight region into dawn dominates over the more classical pre-midnight wedge electrojet of substorms and continues over the long period of main phase development. Specific examples and statistical results will be presented, with dominant attention on the electrojet configuration and it relationship to the evolution of the Dst.