West African Monsoon
Monsoons are large scale perturbations of the tropical atmospheric flow induced by the ocean-continent seasonal temperature contrast, which changes the wind direction driving the ocean moisture inland and causing abundant rainfall. The monsoonal climate affects all the continental masses in the tropical belt: Africa, Asia, Australia and America.
We work specifically on the West African monsoon (WAM) in order to explore the teleconnection with the Mediterranean basin in summer. The WAM originates in the Gulf of Guinea when the thermal sea-land contrast turns the easterly flow in the planetary boundary layer to south-westerly, advecting ocean moisture inland and triggering the rainfall. Fluctuations of the WAM have an impact on the North Atlantic anticyclone and on the Libyan high: a strong monsoon intensifies the Hadley meridional circulation, with a strengthening of the north Atlantic anticyclone and a block of the westerly flow in the Mediterranean; a more inland penetration produces a northern shift of the Libyan high, with subsidence and anticyclonic flow affecting mainly the West Mediterranean.
Through statistical analysis of ocean and atmospheric variables in gridded datasets, we study the climatology, the decadal trends and the interannual variability of the WAM and the impact on the summer Mediterranean climate. We developed operational tools to forecast the onset, the duration and the intensity of the monsoonal season.