One Year of Systematic Aerosol Lidar Measurements in the Troposphere

In the frame of the EARLINET project, a network of lidar stations is performing systematic measurements to provide a climatological database for the spatial distribution and variability of aerosol over Europe. The EARLINET dataset will contribute considerably to quantify aerosol concentrations, radiative properties, long-range transport and budget, and prediction of future trends. The IMAAA-CNR lidar station operational at Tito Scalo (PZ) (Southern Italy, 40° 36'N, 15° 44'E, 820 m above sea level) carried out systematic aerosol backscatter and extinction measurements in the troposphere since May 2000. The aerosol backscatter measurements were performed both at 355 nm and at 532 nm, whereas aerosol extinction coefficient is retrieved from N₂ Raman backscatter signals at 386.6 nm. The observations, performed on a regular schedule, comprise two night-time and one daytime measurements per week. Moreover, an extended observation of Saharan dust episodes has been performed. In this last case, back-trajectories derived from the weather prediction model of the German Weather Service were used to characterize the history of the air parcels. The daytime regular measurements, carried out around 13:00 UT, concern a well developed boundary layer condition. The two night-time regular observations, around sunset, are characterized by low background light allowing Raman extinction measurements, as well as monitoring of the dust layer developed during the day. Furthermore, these last measurements allow the characterization of the aerosol properties in terms of the extinction-to-backscatter ratio (lidar ratio). In this communication preliminary results of the first year of measurements will be presented and discussed. Particular attention will be devoted to the analysis of the aerosol lidar ratio in different meteorological conditions and as a function of the seasonal period. The influence of special events, such as Saharan dust, will be also discussed.