Altitude-resolved properties of a Saharan dust event over the Mediterranean

Some insight is provided about the time and altitude evolution of a Saharan dust event observed by lidar during the spring 1999 EU campaign PAUR-II at Crete (35 degreesN-23 degreesE). The dust episode lasted approximately eig ht days, reaching maximum optical depth tau approximate to 0.6, at 532 nm. Clear tropospheric conditions (tau approximate to 0.1) preceded and followe d the event. Maritime aerosols, mixed-phase clouds and cirrus-generating pa rticles were also observed during the campaign. An altitude-resolved descri ption of lidar-derived backscatter and depolarization of observed aerosols and clouds is provided. The nature and phase of the particles is inferred o n the basis of these variables. Particles extinction and surface area are e stimated on the basis of an aerosol model. The data analysis shows how Saha ran dust events can reach and persist in the 10 km altitude region, overtur ning the vertical structure of the tropospheric aerosol optical depth. The analysis will also show that both aerosols and clouds mainly existed as mix ed phases of solid and liquid particles. (C) 2000 Elsevier Science Ltd. All rights reserved.