Variation in Primary Radioclimatic Variables, And Its Effects on Radio Signal Propagation at the Lower Troposphere.
Radio refractivity and refractive index are important radioclimatic parameters that influence radio wave propagation. The impact of these variables depends on the variation of the measured data of the primary radioclimatic parameters (temperature, relative humidity and atmospheric pressure) with height at lower troposphere. The data of the study was collected via two wireless weather station using Vantage pro2, one stationed at ground surface while the other is at 100 m height in Nsukka (7.30oE, 6.45oN). The study covers twelve months of which the data collected was used to compute the values of the variables and the effect in the variability on radio signal propagation. The result shows that refractive index decrease with an increase in height and thus, refractivity gradient also decrease from normal – 40 dN / Kilo meter to – 127 dN / Kilo meter for eleven months, thereby resulting to super- refraction propagation condition, while in one month the refractivity gradient increases from normal value – 40 dN / Kilo meter to – 28 dN / Kilo meter which cause sub-refraction. Clearly, all these results affect radio wave propagation which limits its reception in Nsukka, South-East, Nigeria.
Keyword: Refractivity Gradient, Index of Refraction, Signal Fading, and Propagation Conditions.