Abstract:
The vertical profile of temperature, moisture and pressure are mostly responsible for the way radio
waves propagate in a given air layer (atmosphere). The atmospheric parameters among others is
dynamic in nature hence there is a need to continuously assess their impacts on radio
communication network which necessitated this study. In this study, ERA-INTERIM satellite data
for six (6) different locations in the coastal areas of Nigeria; namely: Bayelsa, Cross-river, Lagos,
Delta, Ondo and Rivers were used. Five years ERA-INTERIM satellite data was accessed from
from January 2014 to December 2018 with 0.25 by 0.25 resolution was used in evaluating the
vertical distribution of atmospheric anomalous propagation conditions at different altitudes for 110
m, 540 m and 988 m. The meteorological parameters for the locations were used to calculate the
radio refractivity, modified refractivity and modified refractivity gradient at different altitudes.
The result of this study shows that modified refractivity gradient values are generally high during
the rainy season (April-October) and during the dry harmattan season (November - May), the
values of modified refractivity gradient are generally low. The highest negative value of modified
refractivity gradient G was notably observed 110 m above ground level (at pressure level 1000
hPa). Further result shows the occurrence of duct refraction is high at altitude110 m above the sea
level. The degree of occurrence of ducting condition reduces with increasing altitude across the
coastal locations. The occurrence of standard refraction propagation is more achieved at higher
altitude and its noticed at altitude 988 m above the ground level. There is slight occurrence of sub-
refraction condition at 110 m, it reduces with increasing altitude, which further disappears at 540
m and 988 m above the ground level across the coastal locations. This work would assist
subsequent researches.
