Some preliminary results are presented of the fine structure profiles of surface radio refractivity, Ns,
over Ota, Southwest Nigeria (6° 42'N, 3° 14'E) computed from in-situ, one minute interval
measurements of surface pressure, temperature and relative humidity. A wireless Davis Vantage
Pro2 Weather Station instrument installed at the Department of Physics, Covenant University, Ota in
April 2012, was used to obtain the measured variables. Hourly, daily and monthly average values of
surface water vapour density, dry, wet and total radio refractivity were obtained for the months of
April 2012 to March 2013. The distance to the radio horizon for a given transmitter height may be
deduced from the observation that Ns is well correlated with the gradient of refractivity over the first
kilometer above ground. Refractivity gradients utilized for the work were those obtained in a previous
work for Oshodi, a meteorological weather station near the coast and close to Ota
