Performance Analysis of Tropospheric Radio Refractivity along with Refractivity Gradient and Effective Earth Radius in the Coastal Zone of Nigeria

Study’s Excerpt Analysis of the variability in tropospheric radio refractivity in Ogoja and Warri, Nigeria, was carried out by examining a 42-year dataset (1981-2022) of meteorological factors obtained from NASA. The contributions of dry and wet terms to radio refractivity variations were identified and key parameters such as refractivity gradients and the effective earth radius (k-factor) for both locations were evaluated. The radio wave propagation in the region is lowest during the dry season. Full Abstract Radio refractivity is the ratio of the velocity of radio waves in a specific medium to that in free space. Radio waves propagate according to variations in tropospheric radio refractive index. This study used the refractive index and other pertinent meteorological factors to calculate the radio refractivity of the seasonal troposphere and analyse its variability with monthly temperature, relative humidity, and atmospheric pressure measurements that were collected from the National Aeronautic and Space Administration (NASA) for Ogoja and Warri over a forty-two-year period (1981 to 2022). We looked at the proportion contributions of the dry and wet term radio refractivity, the refractivity gradient, and the effective earth radius. The outcome signified that in the two locations, radio refractivity values were lowest for the dry season and highest during the rainy season. For Ogoja and Warri, the highest and lowest average radio refractivity values recorded in the wet and dry seasons are, respectively, 382.9085 N-units in May, 346.4311 N-units in January, and 390.9042 N-units in April, 370.3009 N-units in January. For Ogoja and Warri, the wet term (Nwet) provides 31.5210 % and 30.1793%, respectively, to the primary variation in radio refractivity's overall value, whereas the dry term (Ndry) adds up to 69.8207 % and 68.4790 %. Mean refractivity gradients of -43.8326 and -44.5326 N-units/km were found in the subject areas under examination. Furthermore, it was discovered that the mean effective earth radius (k-factor) for Warri and Ogoja were 1.3959 and 1.3873, respectively. The values provided represent the propagation conditions of superrefraction.