Multi-wavelength Raman lidar, sun photometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece

摘要

A novel procedure has been developed to retrieve, simultaneously, theoptical, microphysical and chemical properties of tropospheric aerosols witha multi-wavelength Raman lidar system in the troposphere over an urban site(Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtainedduring the European Space Agency (ESA) THERMOPOLIS project, which took placebetween 15–31 July 2009 over the Greater Athens Area (GAA). We selected toapply our procedure for a case study of intense aerosol layers that occurred on20–21 July 2009. The National Technical University of Athens (NTUA) EOLE6-wavelength Raman lidar system has been used to provide the verticalprofiles of the optical properties of aerosols (extinction and backscattercoefficients, lidar ratio) and the water vapor mixing ratio. An inversionalgorithm was used to derive the mean aerosol microphysical properties (meaneffective radius (), single-scattering albedo ) and mean complexrefractive index ()) at selected heights in the 2–3 km height region. Wefound that was 0.14–0.4 (±0.14) μm, ω was 0.63–0.88 (±0.08)(at 532 nm) and ranged from 1.44 (±0.10) + 0.01 (±0.01) to1.55 (±0.12) + 0.06 (±0.02), in good agreement (only for the values) with in situ aircraft measurements. The water vapor and temperatureprofiles were incorporated into the ISORROPIA II model to propose a possiblein situ aerosol composition consistent with the retrieved and values. Theretrieved aerosol chemical composition in the 2–3 km height region gave avariable range of sulfate (0–60%) and organic carbon (OC) content(0–50%), although the OC content increased (up to 50%) and the sulfatecontent dropped (up to 30%) around 3 km height; the retrieved low value (0.63), indicates the presence of absorbing biomass burning smokemixed with urban haze. Finally, the retrieved aerosol microphysicalproperties were compared with column-integrated sun photometer CIMEL data.