Optical-microphysical properties of Saharan dust aerosols and composition relationship using a multi-wavelength Raman lidar, in situ sensors and modelling: a case study analysis
1National Technical University of Athens, Laser Remote Sensing Laboratory, Zografou, Greece
2National Observatory of Athens, Institute for Space Applications and Remote Sensing, Athens, Greece
3National Technical University of Athens, School of Mining and Metallurgical Engineering, Zografou, Greece
4Physics Instrumentation Center for General Physics, Troitsk, 142190 Moscow, Russia
5Georgia Inst. of Tech., School of Earth and Atmos. Sc. and Chem. & Biomolecular Engineering, Atlanta GA, USA
6Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology Hellas (FORTH), Patras, Greece
Abstract. A strong Saharan dust event occurred over the city of Athens, Greece (37.9° N, 23.6° E) between 27 March and 3 April 2009. The BSC-DREAM8b model was used to forecast the dust event and to provide the vertical profiles of the aerosol concentration. Due to mixture of dust particles with low clouds during most of the reported period, the dust event could be followed by the National Technical University of Athens (NTUA) 6-wavelength Raman lidar system only during the unclouded day of 2 April 2009. The lidar data obtained were used to retrieve the vertical profile of the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere. Additionally, a retrieval technique representing dust as a mixture of spheres and spheroids was used to derive the mean aerosol dust microphysical properties (mean and effective radius, number, surface and volume density, and mean refractive index) in different layers between 1.8 and 3.5 km a.s.l. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles obtained by Raman lidar were incorporated into the ISORROPIA II model to infer an in situ aerosol composition consistent with the retrieved refractive index values. PM10 concentrations levels, PM10 composition results and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray) analysis results on sizes and mineralogy of particles from samples during the Saharan dust transport event were used to evaluate the retrieval.