Estimation of refractivity gradients and effective earth radius factor (K-factor) in the lowest 100 m of the atmosphere over Ogbomoso, southwestern Nigeria

Abstract

Upon deviation from standard condition, anomalous propagations are usually experienced in within the atmosphere. As a result, it is very pertinent to considered the value of the tropospheric refractive index while planning, designing and implementing microwave systems. In this study, measurements of meteorological parameters (temperature, relative humidity, and atmospheric pressure) were conducted for a period of 12 months (Jan - Dec, 2021) in Ogbomoso (8.17ºN, 4.24ºE, 372 m above sea level) using a collection of wireless Davis Vantage Pro2 6162 automatic weather stations. The hourly time series of these measured data were extracted and converted to monthly averages and used to compute refractivity, gradient of refractivity, and the k-factor. From the Analyses, results revealed a generally high values of refractivity during the rainy months with a peak value of 359 recorded in May. The values were observed to decrease with increasing height. For the period of this observation, the mean refractivity gradient was found to be 50 N-units/km while the average value of K-factor was 1.49. As a result, it was concluded from these findings that the propagation condition in Ogbomoso is super-refraction.