Rodanthi-Elisabeth Mamouri¹, Alexandros Papayannis¹, Vassilis Amiridis², George Chourdakis³, George Georgoussis³

¹National Technical University of Athens, Physics Department, Laser Remote Sensing Laboratory, Heroon Polytechniou 9, 15780 Zografou, Greece
²National Observatory of Athens, National Observatory of Athens Institute for Space Applications & Remote Sensing Metaxa and Vas. Paulou str. GR¬15236 Penteli, Greece
³Raymetrics S.A., Kanari 5, Glyka Nera, Athens, Greece

The atmospheric Planetary Boundary Layer (PBL) that is sensitive to the effect of the Earth’s surface, control the  flow of heat and momentum between the surface and the free atmosphere, thus playing a key role in the local atmospheric circulation. Over land surfaces in high pressure regions, the boundary layer has a well-defined structure that involves with the diurnal cycle. The three major components of this structure are the mixed layer, the residual layers and the stable boundary layer. Routine measurements of aerosol backscatter coefficient at 355nm and 532nm using a 2- wavelength combined elastic-backscatter lidar have been performed for four years (2003-2006) in Athens, Greece (37.9°N, 23.6°E, at 200m asl.). About 200 range-corrected signal profiles have been used for the determination of the mixing layer height. This height is identified as the height at which the first minima of the derivative of the lidar signal normalized to the backscatter molecular signal occurs. Radiosonde data from the meteorological station in “Hellinicon” (37. 54° N, 23.44° E, at 15m asl) in Athens, Greece at the coast of Athens have been also used for the determination of the PBL height, to verify our lidar estimations. A statistical investigation for the aerosol backscatter coefficient in the boundary layer and the free troposphere has been performed. We have found that the Planetary Boundary layer was higher during the summer than the winter period. A clusters analysis of the data using back-trajectories showed a dependence of the optical parameters on the origin of the air masses sampled.

Oral Presentation Acknowledgements: This work was co-funded by the European Union – European Social Fund (75%) and National Resources (25%) of the Greek Ministry of Development, GSRT/PENED (03-ED-169) Project and Raymetrics SA., in the frame of Measure 8.3 - Operational Program "COMPETITIVENESS" of the Community Support Framework (2000-2006).