Abstract:
Surface meteorological parameters obtained from the archives of Tropospheric Data Acquisition
Network (TRODAN) domiciled at the Centre for Atmospheric Research, Ayingba, a subsidiary of
National Space Research and Development Agency, Abuja, Nigeria have been used to investigate
the effect of humidity on reduced-to-sea level value of surface radio refractivity over six locations
in Nigeria. Two years (January 2007-December 2008) data of temperature, pressure and relative
humidity have been used for the study. The locations are Akure (5.18 0 E, 7.17 0 N), Port-Harcourt
(7.01 0 E, 4.78 0 N), Nsukka (13.04 0 E,5.13 0 N), Markurdi (8.53 0 E, 7.73 0 N), Abuja (9.36 0 ,6.33 0 )
and Lagos (3.24 0 E, 6.27 0 N). The correlation between humidity and reduced-to-sea level value of
surface radio refractivity was determined. Typical values for dry month of January, 2007 are 0.97
for (Port-Harcourt), 0.97 for Makurdi, 0.70 for Lagos, 0.91 for Nsukka, 0.96 for Abuja and 0.97
for Akure. From the result, a high correlation value was established between humidity and
reduced-to-sea level value of surface radio refractivity throughout the months in all the locations
studied. The results obtained also show higher correlation values during the rainy season when
compared with that of dry season. Notably, Port-Harcourt has the highest annual average value of
surface refractivity 417 N-units. While Akure has the lowest annual average value of surface
refractivity 385 N-units when compared to the remaining locations. It was also established that
reduced-to-sea level value of surface radio refractivity has higher values in the early hours of the
day and late night hours.
