Effect of interplanetary magnetic field on ionosphere over the magnetic equator

Abstract

Large and quick changes of the latitude of the interplanetary magnetic field from its southward to northward direction is shown to be associated with the disappearance of theq type of sporadic E layer at the equatorial ionosphere during the daytime or with the reversal ofE region horizontal andF region vertical electron drifts during the hours of daytime as well as nighttime. This phenomenon is suggested as the imposition of an electric field in the ionosphere from the evening to the morning sector of the earth and is thus in a direction opposite to that of the Sq electric field. The resultant electrostatic field on the equatorial ionosphere would be decreased or even reversed from its normal direction. This would result in the reduction of electron drift velocity. On some occasions when the normal Sq field is over-compensated by the magnetospheric electric field, the electron drifts are reversed and the irregularities in the E region due to the cross-field instabilities are inhibited resulting in the sudden disappearance of the q type of Es layers.