CEDAR: AMISR Measurements of Auroral Disturbance Electrodynamics, Including Relations to Harang Reversal and Large-Scale Convection Evolution

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Two-dimensional ionospheric electrodynamics of auroral disturbances are studied with high time resolution using the Advanced Modular Incoherent Scatter Radar (AMISR) at the Poker Flat Rocket Range in Alaska. The electrodynamics associated with the nighttime electric field reversal (known as the Harang discontinuity) and with the temporal evolution of polar-cap convection strength are specific observation targets, and the primary research objective is to understand the physics governing large-scale plasma sheet transport and the electrodynamic coupling of that transport to the ionosphere. Magnetic substorm onsets, substorm growth phase auroral arcs, dynamic pressure disturbances, and auroral poleward boundary intensifications - all of which couple to plasma sheet convection, are included as observational targets of interest for which the electrodynamics of formation, evolution, and decay are established and compared to current substorm theory. In addition, the electrodynamics associated with aurora caused by Alfvenic wave electron acceleration are contrasted with the aurora triggered by static field-aligned potential drops (Inverted-V aurora). The AMISR measurements are placed into a larger regional context of auroral evolution by use of data from optical imagers and magnetometers in Alaska. The strength and evolution of convection in the polar cap is determined using simultaneous measurements from AMISR, the Sondrestromfjord incoherent scatter radar, and the EISCAT Svalbard incoherent scatter radar.