Surface water vapour density and tropospheric radio refractivity linkage over three stations in Nigeria

Relationships of the form Y=α+βXY=α+βX and Y=αXβY=αXβ (α, β, constants) have been established between radio refractivity aloft and surface water vapour density (SWVD), in g/m3 over three radiosonde stations in Nigeria using an analysis of variance (ANOVA) technique on upper air climatological data spanning over a decade (1975–1990).Owing to the difference in the climatological patterns of precipitation at the three stations viz. Oshodi, a coastal station, Minna, a midland station and Kano located in the sub-sahelian region of Nigeria, different values of α and β have been obtained for the stations at the different atmospheric levels considered.Initial tests carried out on the models using monthly mean data of the soundings made over the region in 1993 gave encouraging results. On applying the Kolmogorov–Smirnov test, the upper-level refractivity (Nu) models for all the stations and the low-level refractivity (NL) model for Minna were found to be adequate during the dry season. During the rainy season, only the Nu models for Oshodi and Kano were found to be adequate, others are inadequate.