Evidence for a Geoelectric Field Over the Polar Cap

Abstract

During the period of high solar and geomagnetic activity between 22 May and 25 May 1967, energetic proton fluxes were detected coming up the magnetic field lines from the earth at high magnetic lattitudes ($\Lambda >~65-70°$). Because of the peaking of the flux along the magnetic field lines, the existence of a radial polar electric field is suggested. The average electric-field value required is 0.14 V/m.