Radio Refractive Index Variation with Related Weather Parameters at Surface Level in Ilorin, North Central Nigeria

Statistical analysis of surface radio refractive index and related atmospheric parameters over Ilorin (8o 32" N, 4o 34" E), North Central Nigeria, is presented. One minute interval measurement of temperature, pressure and relative humidity for a period of five years was obtained from the Baseline Surface Radiation Network (BSRN) of the University of Ilorin observatory. The diurnal and seasonal variations of these meteorological parameters especially in the tropics contribute to the analysis of refractivity variations and are needed for the design of efficient radio communication systems. Apart from the conventional deduction of low refractivity values in the dry season and high values in the wet season, the interrelationship of surface refractivity and related weather parameters were explored. The regression analysis carried out shows that mean monthly humidity and refractivity are well correlated with a correlation coefficient of 0.97 while the regression equation for predicting mean monthly refractivity Nfrom the mean monthly relative humidity h is N = 0.881 h 279.