ON THE OCCURRENCE OF COUNTER EQUATORIAL ELECTROJET OVER AFRICA

Abstract:

This study engaged year 2009 data of the horizontal component of the Earth’s magnetic field obtained from four geomagnetic observatories in the East and West African meridians to study the occurrence of counter electrojet along the African longitudes: Ilorin (Nigeria: 4.68°E, 8.50°N; dip latitude, 1.82°S), Addis Ababa (Ethiopia: 38.77°E, 9.04°N; dip latitude, 0.18°N), Lagos (Nigeria: 3.27°E, 6.48°N; dip latitude 3.04°S), and Nairobi (Kenya: 36.48°E, 1.16°S; dip latitude 10.65°S). Data was obtained from the Magnetic Data Acquisition System (MAGDAS) installed and managed by the International Centre for Space Weather Science and Education (ICSWSE), Japan. The diurnal and seasonal distribution of the occurrence of CEJ at Ilorin (West Africa) and Addis Ababa (East Africa) were examined. It was observed that the occurrence of morning CEJ is much prevalent along the East African longitude (90%) than the West African longitude (80.9%), while the evening CEJ is dominant along the West African longitude (82.9%) than the East African longitude (50%). The longitudinal variability in the occurrence of CEJ along these longitudes is attributed to the differences in meridional currents, variation in the local electric field in the ionosphere, and the gravity wave associated vertical winds. The simultaneity and asymmetry in the occurrence of CEJ were also investigated. The morning simultaneity is maximum (100%) is maximum than the evening simultaneity. The occurrence of Asym-2 is much prevalent at both longitudes (41.3%) than asym-1 (4.9%).