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Abstract
This study presents an intercomparison of three active remote sensors (2 lidars and 1 ceilometer) in determining the structure of the Planetary Boundary Layer (PBL) and atmospheric aerosol vertical profiles, in the troposphere over Athens, Greece. Ancillary data from a multi-filter radiometer (MFR) were also used. Each intercomparison is performed during a 2-day period of parallel lidar/ceilometer measurements to monitor the temporal evolution of the PBL structure.
In the first intercomparison, the lidar was provided by Raymetrics S.A. (Greece) and the ceilometer by Vaisala OYJ (Finland). The methodology followed was based on the determination of the mixing layer height using suspended aerosols as indicators of the PBL structure, in conjunction with available radiosonde data. The limitations of each instrument were also examined. The capability of Vaisala¢s CL31 ceilometer to detect aerosol structures in the free troposphere was additionally evaluated against quality assured aerosol profiles provided by the Raman lidar of the National Technical University of Athens (NTUA), during a second intercomparison performed on 23-24 July 2009. These two intercomparisons showed that a ceilometer can provide qualitative description of the vertical aerosol structures, under the assumption of suitable aerosol loads.