Observation of a Saharan dust event in the Central Mediterranean with airborne and ground-based lidars

A Saharan dust event Occurring in the central Mediterranean in July 2002 was studied by an airborne and a ground-based lidar: the airborne lidar was installed aboard the Geophysica stratospheric aircraft, that flew over the Tyrrhenian sea. Ground-based observations, including measurements of aerosol optical depth with a Sun photometer, were carried out from the island of Lampedusa, in the central Mediterranean. Measurements obtained with the two lidars within the dust layer fall on the same airmass trajectory, allowing a comparison of the retrieved profiles. A sharp transition in the aerosol distribution Occurs along the flight of Geophysica: low amount of aerosol is detected North of 39degreesN (along the flight path), while enhanced aerosol backscatter ratio up to 3.5, extending to 4 km altitude, is observed southward. Similar profiles are observed at Lampedusa, which is much closer to the dust source region. with two lidar systems. The transport of desert aerosol was driven by a high pressure system centered over eastern Libya, leading, dust particles over Southern Italy and Greece. The observations are well explained by the different airmass trajectories and by dust transport analyses.