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Dust sources and atmospheric circulation acting in concert to control Saharan dust emission and transport pathways

Kerstin Schepanski, Robert Wagner, Bernd Heinold, Ina Tegen
Leibniz Institute for Tropospheric Research, Leipzig, Germany

 

Studies analysing satellite observations illustrate the spatial and temporal distribution of active and thus emitting dust sources. Here, we present a study discussing the atmospheric dust life-cycle over North Africa including its dust transport pathways towards Europe and across the Atlantic towards the Caribbean. In particular, the role of atmospheric circulation regimes over North Africa that favour (a) dust entrainment into the boundary layer, and (b) dust transport pathways and hence the dust destination region are examined.

Satellite-based information on the spatio-temporal distribution of dust source activation events that are inferred from the 15-minute MSG SEVIRI dust product are linked to atmospheric circulation regimes over North Africa. In order to quantitatively link dust sources, emission fluxes and transport to atmospheric circulation regimes, numerical simulations of the atmospheric dust life-cycle using the mesoscale atmosphere-aerosol model system COSMO-MUSCAT are performed. In particular we have analysed the spatio-temporal distribution of dust sources, atmospheric circulation patterns such as the Monsoon flow, the Harmattan flow, the dynamics of the Saharan heat low, and Mediterranean cold surges, and transport pathways towards Europe and the Caribbean. All atmospheric feature show a significant variability in their spatial extent respectively centre location and strength, which affects the spatio-temporal distribution of DSA events and dust transport pathways ultimately determining atmospheric dust concentrations over populated areas in Europe and overseas.

In concert, the results from this study aim at illustrating the relevance of knowing the dust source locations in concert with the atmospheric circulation. Ultimately, this study addresses the question of what is finally transported towards Europe and across the Atlantic from which source regions - and fostered by which atmospheric circulation pattern. Outcomes from this study contribute to the understanding of varying atmospheric mineral dust contributions to the aerosol burden affecting populated areas around Europe and across the Atlantic.