Aerosol lidar intercomparison in the framework of the EARLINET project. 1. Instruments

This is the abstract of the previous publication [Appl. Opt. 43, 961 (2004)]. the framework of the European Aerosol Research Lidar Network to Establish an Aerosol Climatology _EARLINET_, 19 aerosol lidar systems from 11 European countries were compared. Aerosol extinction or backscatter coefficient profiles were measured by at least two systems for each comparison. Aerosol extinction coefficients were derived from Raman lidar measurements in the UV _351 or 355 nm_, and aerosol backscatter profiles were calculated from pure elastic backscatter measurements at 351 or 355, 532, or 1064 nm. The results were compared for height ranges with high and low aerosol content. Some systems were additionally compared with sunphotometers and starphotometers. Predefined maximum deviations were used for quality control of the results. Lidar systems with results outside those limits could not meet the quality assurance criterion. The algorithms for deriving aerosol backscatter profiles from elastic lidar measurements were tested separately, and the results are described in Part 2 of this series of papers _Appl. Opt. 43, 977-989 _2004__. In the end, all systems were quality assured, although some had to be modified to improve their performance. Typical deviations between aerosol backscatter profiles were 10% in the planetary boundary layer and 0.1 _ 10_6 m_1 sr_1 in the free troposphere