Analysis of the effects of meteorological parameters on radio refractivity, equivalent potential temperature and field strength via Mann-Kendall test

Trend analysis of meteorological parameters (temperature, pressure, and relative humidity) as well as calculated refractivity, equivalent potential temperature (EPT) for a pseudo-adiabatic process, and field strength in Calabar, Southern Nigeria has been analyzed using Mann-Kendall (M-K) trend test and Sen’s slope estimator (SSE). Data of the meteorological parameters were obtained from the Nigerian Meteorological Agency (NiMet) in Calabar for 14 years (2005–2018). Results show that the maximum and average temperature, atmospheric pressure, refractivity, EPT, and field strength all exhibited a positive Kendall Z value with 2.52, 0.33, 3.83, 0.77, 0.44, and 3.18 respectively which indicated an increase in trend over time, with only maximum temperature, atmospheric pressure and field strength showing a significant increase at 5% (0.05) level of significance, since their calculated p values (0.012, 0.0001, and 0.001) were less than 0.05. The relative humidity and minimum ambient temperature had a decrease in trend over time as they both had negative Kendall Z values (− 0.11 and − 1.09 respectively); however, together with the average ambient temperature and refractivity, their trend was not significant at 5% level of significance since their calculated p values were all more than 0.05. Linear regression, correlation, and partial differentiation showed that relative humidity has the most effect on the changes in seasonal refractivity and an indirect relationship with field strength variability. The novel relationship between EPT and refractivity has been discovered to be very strong and positive. Descriptive statistics has been used to portray the seasonal and annual trend of all parameters.