The Study of Surface Radio Refractivity in Awka, South Eastern Nigeria
Ikeh U. Chinelo *
Nnamdi Azikiwe University, Awka, Anambra State, Nigeria
Okeke C. Chukwunike
Nnamdi Azikiwe University, Awka, Anambra State, Nigeria
*Author to whom correspondence should be addressed.
Abstract
This work investigates the radio refractivity over Awka, South Eastern Nigeria using meteorological parameters of surface air temperature, pressure and relative humidity collected from 2013 – 2014 respectively, using Davis weather station vantage pro 2 (with Integrated Sensor Suite, ISS) positioned close to the ground surface. The data were logged at 30 minutes interval continuously for each day during the period. Hourly, daily and monthly averages of radio refractivity during dry and wet seasons were calculated from the data obtained. The result indicated that the radio refractivity during the wet season is greater than the dry season. This is as a result of variation in meteorological parameters such as relative humidity and temperature which cause the radio refractivity to vary at different times of the day; while the pressure variation seems to be insignificant. However, results of the refractivity gradient shows, that the propagation conditions have varying degree of occurrence with super-refractivity conditions observed to be prevalent throughout the two year period. The month of January has the highest value of refractivity gradient while least of about -63 N- units per km occurred in July and propagation implication bearing in mind that the lower the gradient (that is more negative) the more super refractive is the troposphere, and the better the propagation conditions. The results obtained from this work is useful to radio engineers for improving VHF/UHF terrestrial links based on clear- air considerations.
Keywords: Radio refractivity, meteorological parameters, refractivity gradients, troposphere