Impact of Tibetan Plateau on North African precipitation

Abstract

The Tibetan Plateau (TP) plays an important role in regulating the global hydrologic cycle. Using a fully coupled climate model, we conduct sensitivity experiments to quantify the impact of the TP on North Africa precipitation. Removing the TP in the model can enhance North African precipitation. Specifically, North Africa precipitation increases substantially during the rainy season (from May to October) though it remains unchanged during the dry season (from November to April). During the rainy season, the TP’s absence in the model causes an anomalous moisture transport from the Indian Ocean and tropical Atlantic to North Africa, which enhances the moisture convergence over North Africa and increases precipitation there. Later on, the change in the Atlantic, that is, cooling (warming) in the North (South) Atlantic forces a southward cross-equatorial moisture transport anomaly from North Africa to the equatorial Atlantic, decreasing the moisture convergence over North Africa and thus precipitation. In general, the moisture convergence is strengthened in most regions of North Africa due to the TP removal, so the resultant precipitation is increased. During the dry season, atmospheric convection center over the Africa continent is located mainly south of the equator, and there is almost no anomalous moisture transport toward North Africa in response to the TP removal. These results suggest that the uplift of the TP may have led to North African aridity.