Solar flare effects on zonal and meridional currents at the equatorial electrojet station, Annamalainagar

Abstract

During the normal electrojet period, a solar flare produces a positive change in the horizontal (H) field, negative changes in the eastward (Y) field and a negative change in the vertical (Z) field at a northern electrojet station. On average, the ΔY is about 40% of ΔH. During a counter electrojet period, ΔH, due to a solar flare, is negative and ΔY and ΔZ are positive. During a partial counter electrojet period, ΔH may be smaller at equatorial stations compared with other low latitude stations, and ΔY may be positive, or sometimes of very small magnitude. The observed change of ΔY at an electrojet station is suggested to be the combined effect of the flare on the associated Sq current system and on electrojet related meridional currents. These data confirm the seat of the equatorial meridional current to be in the ionospheric E layer.