SURFACE RADIO REFRACTIVITY MEASUREMENTS OVER THREE STATIONS IN NIGERIA

Abstract

Tropospheric radio refractivity plays a pivotal role in determining the path taken by any propagating radio signals within the troposphere. There exist spatial and temporal variations in the distribution of surface refractivity as a result of small variations in the constituent parameters. In this study, the in-situ measurement of air temperature, pressure, and relative humidity was carried out at three (3) meteorological stations in Nigeria namely Akure (7.15oN, 5.12oE); Enugu (6.85oN, 7.39oE); and Minna (9.61oN, 6.55oE). In which to predict the refractive conditions of the atmosphere during the morning, afternoon and evening hours, to know the effect of the variation of each of the metrological parameters on the diurnal and seasonal variation of radio refractivity in the different regions; and to show the trend in diurnal, seasonal and annual variability of surface refractivity in the study locations. The data was obtained from Davis 6162 Wireless Vantage Pro2 equipped with Integrated Sensor Suite (ISS) positioned on the ground surface from which the water vapour pressure and surface refractivity were computed. The field strength variability (FSV) was analysed from the computed surface refractivity. The diurnal, seasonal and annual variations of the surface refractivity were examined across the stations. The results show that surface refractivity is highest in the wet season and low in the dry season. Also surface refractivity values was highest in Enugu than the other two stations of study. The study concludes that the surface refractivity Ns values were high during the wet season while the Field Strength variability, FSV were low at this period. Also Ns values were low in the dry season while the values of Field Strength variability, FSV were high during this period