Fig. 7From: Penetration of the electric fields of the geomagnetic sudden commencement over the globe as observed with the HF Doppler sounders and magnetometersSchematic diagram of a pair of the Earth-ionosphere waveguide for the positive electric potential (Φ+) on the duskside and negative potential (Φ-) on the dawnside, supplied by the PI dynamo through the field-aligned currents in the magnetosphere. The electric potentials are transmitted from the polar ionosphereBack to article page