The investigators will examine the simultaneous development of the transpolar ionospheric electric potential distribution in both northern winter / southern summer, northern summer / southern winter, and equinox conditions. The purpose of this examination will be to answer questions regarding: (1) the simultaneous assymetrical summer/winter development of transpolar potential saturation during strong solar wind driving, when the interplanetary magnetic field is strongly southward, (2) the simultaneous development of reversed electric potential cells in both hemispheres in response to northward interplanetary magnetic field and to determine if there is a similar saturation of the reverse potential cells during periods when the interplanetary magnetic field is strongly northward, and (3) to elucidate the simultaneous electrodynamic response of both hemispheric electric potential patterns in response to solar wind shock waves. Two types of response to solar wind shocks have been identified, the so-called typical response and the atypical response. Examination of the global ionospheric electrodynamics will be undertaken to confirm the hypothesis of the field-aligned electric current distribution that forms to produce the atypical response. The measurements to accomplish these goals will be acquired from the SuperDARN HF radar data base for both hemispheres, augmented by incoherent scatter radar ionospheric drift measurements, DMSP polar satellite ionospheric drift data, and measurements from arrays of high latitude magnetometers. These measurements will be inverted to obtain polar electric potential patterns using the Assimilative Mapping of Electrodynamics procedure. A measurement program using the new AMISR radars in Poker Flat, Alaska and Resolute Canada together with the Sondrestrom radar will enable significant improvement in the specification of the northern potential pattern. A significant aspect of the project will be the training of a graduate student in the measurement and analysis techniques that utilize upper atmospheric radars. The project will accumulate data and understanding that can be utilized to validate various global models and specifically magnetohydrodynamic simulation models of the global, coupled thermosphere - ionosphere - magnetosphere - solar wind system.
