Day-to-day variation of equivalent Sq current system during March 11-26, 1970.

Abstract

The instantaneous equivalent current system of Sq is obtained at every 2 hours from March 11 to 26, 1970 under the assumption of north-south symmetry. Trends in H- and Z-components due to UT dependent disturbance fields are corrected by using the Dst index. It is found that UT variation in the intensity and location of external current vortex is similar to that of September, 1964, though the intensity itself is about twice. Day-to-day variation of Sq is examined by subtracting the UT mean values. The residual patterns are quite different day by day, but on some days they resemble currents generated by semi-diurnal tidal winds, and on other days they seem to be caused by the field-aligned currents in high latutudes. The latter are shown to be correlated with the AE index.