Short Communication: Equatorial electrojet strength in the African sector during high and low solar activity years

The daily variation of the horizontal component (H) of the geomagnetic field for the geomagnetic station at Addis Ababa (AAE)- geomagnetic latitude 5°3' and longitude 109°2', and dip latitude –0.5°- is analyzed for a pair of solar maximum and solar minimum years. The result represents the study of the strength of the electrojet phenomena in the African sector. It is found that the midday peak of .H, which is an indicator of the strength of the equatorial eastward electric field at this station, occurs later in the local summer months than during local winter months. Analysis of delay in the time of occurrence of the peak of .H for the autumnal and equinoctial months show that there is a consistent time delay of one hour between these pair of months. The results emphasize the importance of solar activity and local seasonal variations on the strength of the equatorial electrojet current and are shown to be consistent with the earlier similar work carried out for the American and Indian sectors. Key words/phrases: Autumnal and equinoctial months, equatorial electrojet, solar daily and lunar daily variations SINET: Ethiop. J. Sci Vol.26(1) 2003: 77-81