Optical, size and mass properties of mixed type aerosols in Greece and Romania as observed by synergy of lidar and sunphotometers in combination with model simulations: a case study.

A coordinated experimental campaign aiming to study the aerosol optical, size and mass properties was organized in September 2012, in selected sites in Greece and Romania. It was based on the synergy of lidar and sunphotometers. In this paper we focus on a specific campaign period (23-24 September), where mixed type aerosols (Saharan dust, biomass burning and continental) were confined from the Planetary Boundary Layer (PBL) up to 4-4.5 km height. Hourly mean linear depolarization and lidar ratio values were measured inside the dust layers, ranging from 13 to 29 and from 44 to 65sr, respectively, depending on their mixing status and the corresponding air mass pathways over Greece and Romania. During this event the columnar Aerosol Optical Depth (AOD) values ranged from 0.13 to 0.26 at 532 nm. The Lidar/Radiometer Inversion Code (LIRIC) and the Polarization Lidar Photometer Networking (POLIPHON) codes were used and inter-compared with regards to the retrieved aerosol (fine and coarse spherical/spheroid) mass concentrations, showing that LIRIC generally overestimates the aerosol mass concentrations, in the case of spherical particles. For non-spherical particles the difference in the retrieved mass concentration profiles from these two codes remained smaller than ±20%. POLIPHON retrievals showed that the non-spherical particles reached concentrations of the order of 100-140 µg/m(3) over Romania compared to 50-75 µg/m(3) over Greece. Finally, the Dust Regional Atmospheric Model (DREAM) model was used to simulate the dust concentrations over the South-Eastern Europe.