Modeling of the Equatorial Ionospheric E- layer based on cos c index

Abstract

Daytime hourly values of the critical frequency of the ionospheric E-layer, ¦oE, obtained at Ouagadougou Ionospheric Observatory (12.40N, 1.50W) Burkina Faso, West Africa, have been used to study the general characteristics of the normal E – layer. Modeling of E-layer based on solar zenith angle through cos c index factor was also carried out using the relation ¦oE = a (cos c)n, The years 1985 and 1991 data which are the two years of low and high solar activity were employed. The values of diurnal cos c index, n and coefficient a were obtained for each month of the years considered. The average value of the diurnal cos c index, n and coefficient a, for ¦oE at Ouagadougou were found to be 0.32 and 3.70 for low solar activity, and 0.30 and 4.28 for high solar activity. ¦oE = 3.70 cos c 0.32 and ¦oE = 4.28 cos c 0.30 were deduced for low solar activity and high solar activity respectively. The results show that there is no seasonal variation in the values of n and a for both low and high solar activities. The model was tested with ¦oE data from Korhogo, (9.30N, 5.40W) in Cote-d’Ivoire and there is good agreement between the model and observations. The percentage differences between ¦oE, the model and observed values were found to be within ± 10% for both equinoxes and solstices for the two levels of solar activity.