Variability of Meteorological Factors on Surface Refractive Index over Mowe, a coastal area, in Nigeria

Abstract

Radio climatology is an important factor in understanding radio wave propagation through the lower part of the atmosphere (troposphere). The troposphere is an inhomogeneous medium with time varying properties due to prevailing weather conditions. Therefore, the diurnal and seasonal variations of surface radio refractivity for Mowe via Lagos in south-west, Nigeria were studied. Particular emphasis was laid on diurnal variations of the surface refractivity which is high through the night and drops sharply just before sunrise and starts to pick up slightly around 14:00h to 15:00h. It drops to minimum around 16:00h local time, before it increases again. The sinusoidal pattern of plots obtained for temperature and saturated vapour pressure were alike while that of dry term refractivity is reverse. Similarly, the profiles of relative humidity, pressure, the wet term and total refractivity were also alike. The oscillatory movement of Inter-tropical discontinuity (ITD) largely dictates the weather pattern and accounted for high rainfall in the coastal region where the study is undertaken. The results show that surface radio refractivity generally have higher value during rainy season than dry season particularly which partly coincides with the harmattan period. In general, the diurnal refractivity variation is basically a function of local meteorogy.