Aerosol vertical distribution, optical properties and dust transport in the Western Mediterranean basin (case study: Summer, 2012)

Özet

In this paper, we have analyzed an intense dust event at the end of June 2012 crossing the westernMediterranean basin and reaching southern Europe. The geographical distribution of the dust event, its origins,microphysical and optical properties as well as its vertical distribution have been investigated using satellitedata, AERONET sun photometer retrievals and lidar soundings. On average for the summer 2012, all satelliteAOD derived from MODIS, MISR, SEVIRI and OMI are consistent, while OMI tends to overestimate the AOD.During late June and early July 2012, a major dust outbreak occurred over the North Atlantic and has movedtoward East to cross the Mediterranean up to Northern Italy. Satellite and Sun photometer AOD time series havecaptured this event. Dust event is clearly identified in the AERONET observations using a classification of thecoarse mode AOD and the total AOD. The size distributions of this event observed at the different AERONETstations from Northern Africa to Europe don't show a significant change due to sedimentation and the opticalproperties correspond to an aged dust event, as confirmed by the backtrajectories. The vertical distribution of theaerosol extinction coefficient reveals a complex structure with a large dust layer between 1.8 and 4.8 km AMSLhaving a rather constant extinction coefficient between 0.12 and 0.15 km−1.