Occurrence of Extreme Events in West Africa and Its Relationship with the Madden Julian Oscillation

West Africa region faces frequent catastrophic famines associated with recurrent hazards such as droughts, floods and other climatic extremes. The last IPCC report shows that the frequency and intensity of heavy rainfall events will increase at all levels of global warming. The main goal of this study is to investigate the impact of MJO on the occurrence of extreme rainfall events over the region. The analysis of observation shows that MJO exerts a large and significant impact on the probability of observing extreme precipitation. The Spatial patterns of extreme precipitation frequencies follow those of the mean annual precipitation anomalies. During the convectively enhanced phases, the analysis shows a 50% increase of the probability of observing extreme precipitation in regions along 5ºN and 15ºN over West Sahel and 100% significant increase over the Guinean regions. However during the convectively suppressed ones, the probability of observing extreme precipitation is reduced to below 20% over West Sahel and up to 80% over the orographical regions, East and Central Africa associated with a significant decrease. The impact of MJO on precipitation extreme frequency appears to be more pronounced over the Guineans regions to the south of 12°N. The increased moisture supply over the Gulf of Guinea leads to an increase of extreme precipitation events over the region associated to more moisture transport toward the continent.