Simultaneous Chatanika radar and S3-2 satellite measurements of ionospheric electrodynamics in the diffuse aurora

Simultaneous Chatanika radar and S3-2 stellite measurements have been used to investigate the spatial variation of the auroral zone ionosphere near the equatorward edge of the diffuse aurora. During early evening satellite passes on 2 days in February 1976, the equatorward boundary of the diffuse aurora was nearly overhead at Chatanika. The configurations of E region ionization and conductivity were nearly identical in both passes, but the latitudinal variations of F region ionization were quite dissimilar. During both passes, the ionospheric electric field in the diffuse aurora was directed northward. As a result, the closing current of the field-aligned current system was primarily a Pedersen current, and the eastward electrojet was larger than the northward ionospheric current. Although the morphology of ionospheric conductivity was very similar on the 2 days, different patterns were observed for the latitudinal distribution of electric field and field-aligned current