Abstract:
The meteorological effects on radio wave signals propagating through the troposphere are
of great concerns in the design and performance of radio communication systems. Often,
the effect can lead to anomalous propagation conditions such as ducting. In this study,
effects of temperature on radio duct propagation in coastal areas of Nigeria were
investigated. Four years (January 2015-December 2018) meteorological parameters
namely: air temperature, relative humidity and atmospheric pressure at surface and at
950 hPa pressure levels were obtained from the European Center for Medium-Range
Weather Forecast (ECMWF) at a spatial resolution of 0.25˚ × 0.25˚ for five locations across
Nigerian coastal areas. The locations are: Akpabuyo, Cross River State (4.8808 °N 8.5282
°E), Ekeremor, Bayelsa State (4.9512 °N 5.8143 °E), Badagry, Lagos State (6.4316 °N
2.8876 °E), Port-Harcourt, River State (4.8156 °N 7.0498 °E) and Ilaje, Ondo State
(6.2585 °N 4.7692 °E). Modified radio refractivity and its gradient at surface and at 950
hPa pressure levels were computed using ITU- model. Results on monthly, seasonal and
annual mean values of modified radio refractivity gradient variation over the study
locations were recorded. Ducting occurrence was found during the dry months and the
highest temperature values was found in the month of December with an average values
of 27°C having the highest values of modified radio refractivity gradient in the duct layer.
On location basis, the results show that Akpabuyo, Cross River recorded the highest value
of modified radio refractivity gradient of about 100 M-units/km and the least value
of modified refractivity gradient in the duct layer of about -4 M-units/km were also
found in the same location with temperature of 26oC at 09:00 hr. LT.
