ESTIMATION OF PRECIPITABLE WATER VAPOUR AT SUB-SAHEL REGION OF CENTRAL NIGERIA USING SURFACE METEOROLOGICAL DATA

Using a ten-year monthly averaged data from the Nigerian Meteorological Agency, for three stations in Nigeria, an empirical model of the form lnW = a +bTd (where W is the precipitable water vapour, Td is the dew-point temperature, a and b are constants) was found to be the best model estimation of precipitable water vapour at the sub-Sahel central region of Nigeria. The model was found to agree with other similar models found elsewhere and the goodness of fit statistic for this model was found to be R2 = 0.998, SSE = 0.049 and RMSE = 0.015. Kolmogorov-Smirnov (K-S) test was used to validate the model. Other models using surface relative humidity (RH) and surface ambient temperature (T) were also found with satisfactory statistical performance. The minimum precipitable water vapour for the region was observed to be 24.88±7.82mm in the month of January while two maxima were found in the months of May and October as 46.79±7.82mm and 47.48±7.82mm, respectively. The link between el niňo/la niňa events and the variation of precipitable water vapour in the study area was attempted.