EXTINCTION OF SOLAR RADIATION OVER THE EAST MEDITERRANEAN UNDER SAHARA DUST INFLUENCE

摘要

The extinction of solar radiation due to the presence of dust over the East Mediterranean region has been documented by multi-wavelength aerosol lidar neas-urements at three stations over Greece during August and September 2003. At the southeast located station of Finokalia, on Crete island, a single-wavelength lidar (532 nm) has been operated, whereas in Athens and Thessaloniki backscatter-Raman lidars were used at 355 nm and 532 nm. The aerosol lidar in Athens provided aerosol vertical profiles between 600 m above sea level (asl) and 7 km height with a range resolution of 15 m and a temporal resolution of 1.5 min. The Raman lidar in Thessaloniki measured aerosols between 800 m asl and 3.5 km with a range resolution of 30 m and a time resolution of 6 min. The single-wavelength lidar has been operated to observe aerosol layers from about 400 m asl. to 7 km height with a vertical resolution of 7.5 m and a time resolution of 6.6 min. Absorption and scattering of the surface aerosol layer have been measured by a PSAP and a nephelometer that operated continuously at the Finokalia station. This network of 3 lidar stations allowed the observation of the same dust layers in the height range of 2000-5000 m asl. as well as their spatial evolution over the East Mediterranean region. The lidar ratio values found are characteristic also for rather spherical mineral particles, while the color index values found are typical for desert dust.