Synoptic patterns associated with extreme dust events in the Mediterranean basin

Extreme dust events over the western, central and eastern Mediterranean are identified analysing the aerosol optical depth remote-sensed by the Moderate Resolution Imaging Spectroradiometer (MODIS) in 2001-2010 and simulated by the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model in 2000-2007. The seasonal variability of the dust events and the evolution of the synoptic circulation patterns before and during the events are studied. Results show that the highest occurrence of short events (1-3 days) is in the eastern Mediterranean, while long events (more than 4 days) are more frequent in the western Mediterranean. Short events are concentrated in spring, while long events do not show a clear seasonality. The synoptic circulation patterns accompanying short and long events are similar, and the occurrence across the Mediterranean Basin is related to westerly low-pressure systems. Dust events in the western Mediterranean are associated with high-pressure conditions limiting the development of lows to the western North Africa, while the eastward evolution of cyclones over the central Mediterranean and Northern Africa accompanies dust events in the central and eastern Mediterranean.