Signatures of Temperature on Radio Duct Propagation in Coastal Areas of Nigeria

Abstract

Meteorological parameters: temperature, relative humidity and pressure at the earth’s and 950 hPa pressure level and at 09:00 LT were obtained from ERA-5 satellite data obtained from the archive of European Centre for Medium-Range Weather Forecast (ECMWF) and was used to compute modified radio refractivity and its gradient using ITU-R model. The result of the computation was then employed in deducing the temperature at which radio duct occurs in the coastal areas of Nigeria (Akpabuyo in Cross River State, Ekeremor in Bayelsa State, Port-Harcourt in Rivers State, Badagry in Lagos State and Ilaje in Ondo State). The results showed that high values of modified radio refractivity gradient, M´ were observed during the wet season months with an average value of 102 M-units/km, and low value during the dry season months with an average value of 87 M-units/km. Ducting occurrence were found during the dry months with -13 M-units/km, -12 M-units/km, and -5 M-units/km values respectively. The results show that Akpabuyo, Cross River in state have the strongest value of modified radio refractivity gradients of about 100 M/km and the minimum value of M´ in the duct layer of about -5 M/km. It was also observed that, radio ducts that can trap radio signals in the study locations in Nigeria are formed at temperature of more than 26 ^oC.