Seasonal Variation of High Latitude Auroral Conjugacy

Magnetometer and riometer observations at South Pole, Antarctica and Iqaluit, Canada have been used to study the conjugacy and motion of auroral electrojets in the nightside polar cap. We have found that the auroral electrojets associated with the poleward border of substorm expansion regions reach higher magnetic latitudes in the winter hemisphere than in the summer hemisphere. The inter-hemispheric latitude difference is of the order of 2degree-5degree in summer and winter seasons.