Study of average seasonal variations of surface radio refractivity across some selected cities in Nigeria

Abstract

The average seasonal variations of surface radio refractivity pressure, temperature and relative humidity made across Yola (9 N, 6 o 45' E), Lagos (6 o 27' N, 5 o 12' E), and Port measurement was made using wireless automatic weather station installed at the surface of each station under study. The study utilized three years of meteorological data measured from January 2010 to December 2013 to calculate the surface radio refractivity using empirical form recommended by the International Telecommunication Union (ITU that the average value of surface radio refractivity showed seasonal variations with high values during the rainy season and low values during the dry season surface radio refractivity of 242N-Lagos station. The result also shows that climatic condition is the force behind the seasonal variations of surface radio refractivity in all study stations.

Evaluation of the Vertical Profile of Radio Refractivity and its Gradients in a Tropical Atmosphere

“…The radio refractivity gradient is estimated from [18]: (6) where G is the radio refractivity gradient, while N1 and N2 are the radio refractivity values at heights h1 and h2 respectively. The effective earth radius factor (k-factor) is estimated from [18]: (7) where k is the effective earth radius factor and dN/dh is the change in radio refractivity with height (the radio refractivity gradient). 2 ranged from 326.21 N-Units to 39.86 N-Units from the lowest to the highest altitude.…”

“…The inhomogeneous spatial distribution of the air's refractive index results in undesirable outcomes including multipath fading, interference and attenuation of radio signals. Radio communication, aeronautics, environmental monitoring, disaster prediction, navigation, and radar systems are all hindered by these impacts [7]. This abnormal radio wave propagation results in intense consequences like the full breakdown of communication between the transmitters and receivers or even the missing of intended targets by radars [8].…”