Observations of Ionospheric Propagation Factor at Two African Equatorial Ionization Anomaly Stations Using Ionosonde Measurements

Abstract

The Ionospheric propagation factor of the F-region (M(3000)F2) has the ability to measure the absorption of radio waves aside navigation purposes and Space weather forecasting. Here, the morphology of the M(3000)F2 is considered at two locations within the African equatorial ionization anomaly (EIA) region using ionosonde measurements. Data used spans 1993 to 1996 signaling the descending phase of solar cycle 23 (SC23). Results were presented on a diurnal, seasonal and annual basis. Seasonally, the drop in M(3000)F2 during the post-sunset period is more prevalent in equinoxes and almost absent in June solstice across the entire descending phase period. This drop in M(3000)F2 was also observed to diminish with decrease in solar activity, especially in March equinox. The feature appeared 1-hour earlier in Korhogo ahead of Dakar during the seasons of appearance. The seasonal variation is more coherent at daytime than at nighttime across the entire years at Korhogo in comparison to the observation at Dakar. Annually, high solar activity years are characterized by lower values and vice versa for most of the seasons showing the dependency of M(3000)F2 on sunspot activity. The (M(3000)F2) observation suggests that Korhogo data has a better potential of being included in the development of African regional model than that of Dakar owning to its consistency in the appearance of the post-sunset drop in value feature, which gives a better representation of the height of the peak electron density of the F2 region. Much of the differences noticed in the M(3000)F2 pattern at Dakar and Korhogo, especially during the nighttime period of the entire descending phase is linked to latitudinal circulation/distribution of plasma initiated by fountain effect.