Estimation of Refractivity Gradient and Geoclimatic Factor for Radio Link Design in Nigeria

Accurate estimation of refractivity gradient and geoclimatic factor is highly necessary for radio signal propagation in clear air environment to cater for fade margin, essential for a reliable radio link. This is necessary because of the unstable nature of the environment the signal is traversing. These parameters were estimated from the meteorological parameters of surface air and dew temperature, temperature and relative humidity obtained from European Centre for Medium-Range Weather Forecasts (ECMWF) archive during the period of 36 years. Point refractivity gradient at 100 m with refractive conditions were estimated for different locations across Nigeria in tropical region. The results show that the seasonal variation experience across the locations were influenced by the movement of inter tropical discontinuity. Values of geoclimatic factor also varies seasonally and geographically. Moderate association exist between β factor and latitude with correlation coefficient of 0.45 which is statistically significant as p<0.05. However, weak or non-relationship exist between β, µ, altitude and longitude as indicated by correlation coefficient.