Induction Effects of Geomagnetic Storms in the Geo-Electric Field Variations At West African Dip Equatorial Latitudes

Abstract

Geomagnetic Storms caused by perturbations of the Earth's magnetic field, induce currents within the Earth's crust. The induced currents yield measurable variations in geo-electric field at dip equatorial latitudes in West Africa. The induced effects of geomagnetic storms in the geo-electric field variations at dip equatorial latitudes in West Africa was studied using data obtained from ten West African geomagnetic and telluric electric field stations during the International Equatorial Electrojet Year (IEEY) between 1992 and 1994. Disturbance storm time (Dst) index value of less than -100nT were used to characterize the storm. The analysis was conducted using hourly mean values of the horizontal component (H), the magnetic declination (D) and vertical component of the geomagnetic field (Z) along with the north-south (Ex) and east- west (Ey) components of the geo-electric field obtained from 1992 and 1994 using telluric Field lines operated along the meridian chains of stations across the geomagnetic dip equator in West Africa. The results reveal that the magnitude of the geo-electric field responses due to geomagnetic storms varies depending on the observational station and the daytime enhancements in the telluric field noticeable between 08:00 hours Universal Time and 16:00 UT with slight increase near the dip equatorial stations.