An analysis of the September 2015 severe dust event in the Eastern Mediterranean

In September 2015 one of the severest and unusual dust events on record occurred in the Eastern Mediterranean. Surprisingly, state-of-the-art dust transport models were unable to forecast the event. This study details the reasons for the failure of the models to forecast the dust storm and presents simulations of the event at convection permitting resolution with the modelling system ICON-ART. The results allow for an in-depth analysis of the influence of the synoptic situation, the complex interaction of multiple driving atmospheric systems and the mineral dust radiative effect on the dust event. A comparison of the results with observations reveals the quality of the simulation results with respect to structure and timing of the dust transport. The forecast of the dust event is improved decisively. The event is enabled by the unusually early occurrence of an active Red Sea trough situation with an easterly axis over Mesopotamia. The connected sustained organized meso-scale convection produces multiple cold-pool outflows responsible for intense dust emissions. Complexity is added by the interaction with an intense heat low, the land inward penetrating Eastern Mediterranean sea-breeze and the widespread occurrence of super-critical flow conditions and subsequent hydraulic jumps in the vicinity of the Dead Sea Rift Valley. The newly implemented mineral dust radiation interaction leads to systematically more intense and faster propagating cold-pool outflows in the runs including the mineral dust radiation interaction.