Review of methodology to obtain parameters for radio wave propagation at low altitudes from meteorological data: New results for Auchi area in Edo State, Nigeria

Abstract

The surface refractivity, the refractivity gradient and effective earth radius factor (k-factor) are useful ingredients for predicting the local radio wave propagation conditions in the troposphere. In this study the surface refractivity, refractivity gradient and k-factor were estimated and analyzed from the measurements of air temperature, relative humidity and atmospheric pressure in Auchi area of Edo State, Nigeria which is located within Latitude 7.07°N and Longitude 6.27°E using a set of three self designed cost effective portable weather monitoring systems for a period of two years (2016 and 2017) in order to derive the radio propagation conditions. The weather monitoring devices were positioned at three different height levels of 50, 100 and 150 m at the administrative block of Edo University Iyamho, Auchi area of Edo State, Nigeria of about 200 m height for the measurements of the atmospheric weather variables respectively. The results show that the surface refractivity and the k-factor values were generally higher during rainy seasons compared to that of the dry seasons; while the refractivity gradient values were higher in the dry seasons compared to the rainy seasons and that surface refractivity was inversely proportional to the height; while the refractivity gradient and the k-factor have no defined pattern of proportionality variance with the height for the period under consideration. The average values of the surface refractivity, refractivity gradient and the k-factor for the period under consideration are 355.83 N-units, −55.85 N-units/km and 1.50 respectively. Consequently, it is deductively concluded that the local radio propagation condition for the Auchi area of Edo State, Nigeria is predominantly super-refractive.