OPTICAL, MICROPHYSICAL AND CHEMICAL PROPERTIES OF TROPOSPHERIC AEROSOLS RETRIEVED BY A 6-WAVELENGTH

A 6-wavelength Raman lidar system has been used to retrieve the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere over an urban site [Athens, Greece (37.9oN, 23.6oE, 200 m a.s.l.)] during a large biomass burning event occurred on June 28-30, 2007. The hybrid regularization technique was used to derive the mean aerosol microphysical properties (effective radius, surface-area concentration, volume concentration, single-scattering albedo (ω) and mean complex refractive index) in the lower troposphere. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles were incorporated into the thermodynamic model ISORROPIA to infer the chemical parameters of the aerosols (water content, dry chemical composition) that are consistent with the retrieved ω and refractive index values. The plumes of June 28-30 were simulated by the FLEXPART code, run in the backward mode, which showed high emission sensitivity in the burning area for air masses arriving between 0- to 4200-m height over Athens. The CO source contribution was also maximum between 0-to 250-m height. 1