Irregular geomagnetic activity in the northern and southern hemispheres associated with IMF sector boundary passage

Abstract

Kn and Ks, the northern and southern hemispheric indices of geomagnetic activity, for the period 1959-1974 are analysed to examine the influence of solar magnetic sector boundary passage. It is shown that hemispheric difference in activity is a function of the type of sector boundary and that greater change is associated with a +/- boundary. Occurrence frequency of the index 0 depicts a significantly larger response in association with a +/- boundary, only for the southern hemisphere index. Ratios of occurrence frequency of Ks to Kn, as a function of sector boundary passage, show significant departures only for indices 0 and 5, indicating two regions of solar wind velocities that cause significant differences in geomagnetic activity of the two hemispheres.