On the geomagnetic solar quiet daily variation field during the IGY

The geomagnetic solar quiet daily variation field, Sq, was studied separately for three longitudinal zones during each of three seasons using IGY data obtained at 69 stations. Equivalent external (overhead) and internal (induced within the earth) electric current systems responsible for Sq variations with respect to dip latitude were estimated by the method of spherical harmonic analysis in each zone for each season. Particularly interesting results are the large current intensity during equinoxes and the asymmetry between the northern and southern hemispheres for equinoctial months and even for the yearly average.