Relationship between Interannual Rainfall variability over Western Kenya and The Southern Oscillation.
Ininda, J M
Kihuga, J N
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Western Kenya, which comprise the highlands west of the Rift Valley and the Lake Victoria basin, receive substantial amount of rainfall almost throughout the year. This region has therefore a high agricultural potential. The characteristics of rainfall in this part of the country are influenced by several factors, which range from meso-scale to global. One of the global teleconnection systems that influence the rainfall over this region is the Southern Oscillation (SO). The SO is an irregular, interannual and global scale see saw fluctuation in surface pressure between Indonesia and Southwest Pacific, and occurs at interval of 2 to 7 years. Both the rainfall and Southern Oscillation Index (SOI) data were obtained from the Drought Monitoring Centre (DMC) in Kenya. The Data consisted of monthly rainfall from 24 stations distributed over the region and the monthly-normalized SOI. The period of study was between 1957 to 1993. The seasonal data was derived from the data. The monthly and seasonal rainfall and SOI were subjected to correlation analysis. The t-test was used to determine the statistical significance of the computed correlation values. The spatial and temporal patterns of the correlation values were used to determine the nature of the relationship between the SO and rainfall over western Kenya during various months and seasons. Significant positive correlation values were observed during the months of July- September, while significant negative correlation values were observed during October-December. Low correlation values were however observed during January- May. The significant correlation values observed during July-September and October-December suggest that the SOI can be used as a predictor for the rainfall during these seasons