Control of atmospheric export of dust from North Africa by the North Atlantic oscillation

AU year long, massive airborne plumes of desert dust from the Sahara and surrounding regions are exported to the North Atlantic Ocean(1) and the Mediterranean Sea(2). The mass of African dust transported in the atmosphere is large-about one billion tonnes per year (ref. 3)-and it has been suggested that the windblown dusts have a substantial influence on the regional radiative budget(4-6). Here we use daily satellite observations of airborne dusts(7) to obtain an 11-year regional-scale analysis of dust transport out of Africa. The substantial seasonal variability over the Atlantic Ocean and Mediterranean Sea can be explained by the synoptic meteorology, Interannual variations in dust transport are similar over both regions, and are well correlated with the climatic variability defined by the North Atlantic Oscillation(8). This large-scale climatic control on the dust export is effected through changes in precipitation and atmospheric circulation over the regions of dust mobilization and transport, Such natural variability is so large that it is difficult to resolve any anthropogenic influences on atmospheric dust loads, such as those due to desertification or land-use changes. It seems likely that the North Atlantic Oscillation will also affect the distribution-and radiative influence of other aerosols.