Desert aerosol transport in the Mediterranean region as inferred from the TOMS aerosol index

We proposed to identify the sources of desert dust aerosols with local maxima of the TOMS aerosol index distribution averaged for the long period. Being simpler than the approach based on a dusty days occurrence, our method gives the same results. It was first shown that in spring-summer, the flux of dust from the sources located at latitude ∼16°N and longitude ∼16°E and around latitude ∼19°N and longitude ∼6°W exceed the sinks due to settling and transport. As a result the atmosphere over North Africa is almost permanently loaded with a significant amount of mineral desert dust in spring and in summer. It is also shown that the Chad basin source located around latitude 16°N and longitude 16°E is relatively more stable with a maximum activity around April. The region around latitude 19°N and longitude 6°W appears as a more variable source with maximum in July. Low pressure systems, called Sharav cyclones, mobilize the already suspended mineral dust and transport it eastward and northward along the Mediterranean basin. A new method for description of dust plumes propagation was applied to the study of dust events in the Mediterranean Sea and enabled us to follow their dynamics. Identifiable dust plumes appear first in the western sector of the sea and then move eastward with a speed of about 7 to 8 degrees per day. In spring, this motion continues at least up to the eastern coast of the Mediterranean. In summer the dustplume is prevented from penetrating further east of about 15°E.