Electric field mapping in the ionosphere at the equatorial plane

The relationship between the components of electric field perpendicular to the magnetic field line in the ionosphere and at the equator is computed for dipole and distorted magnetic field models under the assumption that magnetic field lines are electric equipotentials. Since the electric field direction is not preserved in this mapping process one can resolve the apparent conflict between electric fields measured in the ionosphere and convection patterns in the equatorial plane. The possible error in the assumption that magnetic field lines are electric equipotentials is discussed.