Regional variation of columnar refractivity with meteorological variables from climate monitoring satellite application facility (CM SAF) data over Nigeria

Data from satellite application facility on climate monitoring (CM SAF) have been used to estimate and study seasonal variation of columnar refractivity in relation with relative humidity and temperature for twenty six stations categorized into four climatic regions (coastal, Guinea savannah, midland and sub Sahel regions) over Nigeria. Mean, standard error, maximum, minimum values and ranges of these variables were also determined for different regions at each atmospheric level. The results have revealed that the monthly variation of refractivity along side with meteorological factors (relative humidity and temperature) from one region to another over Nigeria are influenced by seasonal variation, geographical location and environmental situation of each region. It is also noticed that the range of relative humidity and temperature are wider in the northern part (56.19 and 72.51% and 5.64 and 5.90 K respectively) compared to the southern part (17.85 and 25.27% and 3.19 and 5.44 K respectively) of the country. This effect was observed in the variation of refractivity also. Effect of inter tropical discontinuity (ITD) was recorded in the southern variation of relative humidity and refractivity.   Key words: Columnar, refractivity, meteorological, variation.