Impact of large scale climate oscillation on drought in West Africa

Abstract: Drought poses a significant threat to the delicate economies in subsaharan Africa. This study investigates the influence of large scale ocean oscillation on drought in West Africa. Standardized Precipitation Index for the region was computed using monthly precipitation data from the Climate Research Unit during the period 1961 -1990. The impact of three ocean oscillation indices - Southern Ocean Index (SOI), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO) on drought over West Africa was investigated using linear correlation, co-integration test, mutual information and nonlinear synchronization methods. SOI showed predominantly positive correlation with drought over the region while PDO and NAO showed negative correlation. This was confirmed by the co-integration tests. The nonlinear test revealed more complex relationship between the indices and drought. PDO has lesser influence or contribute less to the drought in the coastal region compared to the Sahel region of West Africa.