Seasonal Variation of Radio Refractivity of Some Selected Stations in Northern Nigeria

The seasonal variation of radio refractivity of some selected stations (Abuja, Lafia, Bauchi, Kaduna, Maiduguri, and Sokoto) in Northern Nigeria was analysed using surface meteorological data sourced from the Nigerian Meteorological Agency for five years (2007-2011). From the analysed result, seasonal variation of radio refractivity was observed with higher refractivity during the wet season. The maximum refractivity during the study period was about 385 N-unit recorded in Lafia during the month of August and the minimum was about 282 N-unit recorded in Maiduguri during the month of March. The mean field strength recorded was found to be between 19 dB and 3 dB for the study stations. This implies that the output of the receiving antenna in the region may be subjected to variations of not less than 3 dB on a year and can be as high as 19 dB.