ASSESSMENT OF REDUCED - TO - SEA - LEVEL VALUES OF MICROWAVE RADIO REFRACTIVITY OVER NIGERIA

Abstract

The knowledge of the variation of surface radio refractivity is required for planning of broadcasting services including terrestrial radio links over a region. The reduced–to–sea–level refractivity, No, values will remove the elevation–dependence of surface refractivity in a bid to enhance comparison and contouring of values for different meteorological stations. This work presents the results of the diurnal, seasonal and annual variations of reduced-to-sea-level values of radio refractivity over Nigeria. The work employs two years (January 2011 to December 2012) of in-situ measurement of atmospheric pressure, temperature and relative humidity meteorological data from seven locations (Abuja, Akure, Lagos, Makurdi, Nsukka, Port-Harcourt and Jos). The data ware obtained from Tropical Data Acquisition Network (TRODAN) of the Centre for Atmospheric Research (CAR) located in Anyigba, Kogi State. The results show that reduced–to–sea–level refractivity values, No, were observed to be high between the early hours of the day and low during sunset and sunrise and high again during the night across the seven stations. It was also deduced that No values were high during the raining season and low in the months of dryness/harmattan. Also variation of reduced–to–sea–level refractivity, No, at Port-Harcourt has the highest value while that of Jos has the lowest value.