Electric field measurements in the auroral ionosphere

Vector electric field and particle intensity measurements have been made on a sounding rocket launched into a visible aurora near local midnight. Preliminary results of the dc electric field measurement indicate that electric fields as large as 85 millivolts/meter were observed, that the component of the electric field in the plane perpendicular to the magnetic field direction pointed generally equatorward, and that the component of the dc electric field along the magnetic field direction had a magnitude as large as 20 millivolts/meter.