Abstract:
Rainfall in the tropics is closely linked with other environmental attributes. The influence of Sea
Surface Temperature (SST) and terrestrial radiation on West African Summer Monsoon was
investigated in this study. This was done by examining the variability of atmospheric circulation
features, sea surface temperature and outgoing longwave radiation during West African Summer
Monsoon. The interactions between these features and West African Summer Monsoon were also
determined. Principal component analysis was also used to find the percentage contribution of
forcings on West African Summer Monsoon. The Era Interim reanalysis data were sourced from
European Centre for Medium-Range Weather Forecast (ECMWF) with a resolution of 0.1250*
0.1250 from 1998-2012 for 10m U-wind at various pressure levels, Total Precipitation and Sea
Surface Temperature. Outgoing Longwave Radiation (OLR) was obtained from Climate
Diagnostic Centre for the same period. Extraction and analysis of data were carried out using ferret
and Microsoft excel. The study shows a strong positive correlation between Rainfall and SST
which increases from the Guinea up to the North and a strong negative relationship between
Rainfall and OLR. The wind profile also indicated the presence of moisture throughout the
monsoon period. The African Easterly Jet and the Tropical Easterly Jet shown are precipitation or
rainfall producing mechanism and represent, among others, major factors or features that influence
rainfall, beside Sea Surface Temperature (SST) and Outgoing Longwave Radiation (OLR). The
first two principal components for April to October explain 74.2% of the total variance.
