On the position of the focus of the geomagnetic<i>S_q</i>current system

Abstract

This paper reviews present knowledge about the Sq foci, discusses the cause of changes in the Sq field, and describes problems concerning the determination of the Sq focus. It is concluded that the foci in the potential fields of geomagnetic Dq variations may be taken as approximately indicating the positions of ionospheric Sq current foci.