  Radio refractivity, which is the bending of radio signal as it propagates
through media, is very important in works involving terrestrial atmospheric
electromagnetic propagation such as point-to-point microwave communication,
terrestrial radio and television broadcast, mobile communication system, and so
on. This study has focused on the West African region where it was found that
the region has a refractivity which varies exponentially with height and from
the coast towards the desert. Generally, refractivity gradient was found to
range between -46.48 and -29.51 N-units/km (k-factor value of between 1.23 and
1.42) across the region, splitting the between sub- and super-refraction. The
variation in refraction type was found to follow seasonal pattern across the
West African region, with sub-refraction dominating during dry season and
super-refraction dominating most part in the coastal area during the wet
season.
