Features of Quiet-time Magnetic Field and Simple Approach to Estimate the Variability Strength of Equatorial Electrojet (EEJ) Current Intensity

It is a widely accepted fact that the quiet-time equatorial electrojet (EEJ) is a prominent narrow band of enhanced daytime eastward current flowing basically in the ionospheric E-region within ± 3° latitude of the dip equator. Studies have shown over the years that at least two magnetic stations are required to estimate the daytime variability strength of the EEJ. One station must be situated within the EEJ strip (station whose EEJ strength is to be determined) and the other displaced just outside the EEJ influence. One of the open issues in estimating the strength of the EEJ has been the actual latitudinal distance of the off-equatorial station from the equatorial region. This has given rise to different schools of thought in estimating the variability strength of the EEJ. This paper outlined for the first time the latitudinal extent required of the off-equatorial station which is longitudinally aligned with the equatorial station and step-by-step procedure required for estimating the daytime equatorial electrojet and the latitudinal extent ideal for choosing the off-equatorial station aligned to the equatorial station. The result from this study will clarify on the latitudinal extent required for estimating the variability strength of the EEJ in the African sector and invariably provide to some extent the role of equatorial electrojet on the distribution of equatorial ionization at low latitude in this region.