Analysis of radiosonde data on tropospheric water vapour in Nigeria

Abstract

The analyses of some atmospheric water vapour parameters derived from radiosonde data at the three existing radiosonde stations in Nigeria are reported. The stations essentially represent the climates of the southern (coastal), middlebelt (savannah), and northern (sub-sahel) regions of the
country. Monthly means of the height profiles of water vapour density over a nine-year period, the approximate exponential distribution of the variable within an approximate 10km height from surface and harmonic analysis of the seasonal variations of total precipitable water vapour are
presented. The correlation between observed surface water vapour density and that derived from the exponential distribution with height are deduced. It is observed that at both inland stations parameters show marked variability and seasonal dependence compared to the coast, which exhibits
higher values, but less variability. Results also show that the exponentially deduced water vapour density reasonably reproduces measured altitude profiles of the vapour density and that the harmonic analysis highlights more clearly the seasonal and annual variations of total precipitable water. The first three harmonics derived were found to account for over 80% of the total variation.