Radio refractive index in the lowest 100-m layer of the troposphere in Akure, South Western Nigeria

Abstract

The structure of the radio refractive index “in altitudes of” first 100 m of the troposphere is important for the planning and design of microwave communication “links”. For this reason, measurements of atmospheric pressure, temperature, and relative humidity were conducted in Akure “(7.15°N, 5.12°E)” to determine the radio refractive index. “Wireless meteorological sensors were positioned at the ground surface and at 100 m altitude on a 202 m high tower owned by the Nigerian Television Authority (hereafter NTA) which is now idle due to the relocation of the television house”. The measurements were “made” every “30 min” and round the clock. “Statistical” distributions of the refractive index modulus, “its” vertical gradient, and the diurnal and seasonal variations of the refractivity modulus were determined from the measured “data”. The results obtained show that the local climate has an appreciable influence on the radio refractivity. The curve of the seasonal variation of the vertical gradient of the radio refractive modulus has some minima points corresponding to the dry and the rainy seasons in Akure. The results obtained also show that the values of the refractive modulus at the “100 m” altitude were high in the morning and late evening/night hours while they “show” minima during the afternoon hours. Thus, the worst propagation condition obtained for Akure was observed in the afternoon “within” the time window “from 15:00 to 18:00” local time (hereafter LT) during the dry months and from roughly 17:00 to 19:00 LT during the rainy season.