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Author: Müller, D. × Subject: airborne survey ×

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    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
    (München : European Geopyhsical Union, 2012) Mamouri, R.E.; Papayannis, A.; Amiridis, V.; Müller, D.; Kokkalis, P.; Rapsomanikis, S.; Karageorgos, E.T.; Tsaknakis, G.; Nenes, A.; Kazadzis, S.; Remoundaki, E.
    A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a 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 obtained during the European Space Agency (ESA) THERMOPOLIS project, which took place between 15–31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers that occurred on 20–21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius (reff), single-scattering albedo ω) and mean complex refractive index (m)) at selected heights in the 2–3 km height region. We found that reff was 0.14–0.4 (±0.14) μm, ω was 0.63–0.88 (±0.08) (at 532 nm) and m ranged from 1.44 (±0.10) + 0.01 (±0.01)i to 1.55 (±0.12) + 0.06 (±0.02)i, in good agreement (only for the reff values) with in situ aircraft measurements. The water vapor and temperature profiles were incorporated into the ISORROPIA II model to propose a possible in situ aerosol composition consistent with the retrieved m and ω values. The retrieved aerosol chemical composition in the 2–3 km height region gave a variable range of sulfate (0–60%) and organic carbon (OC) content (0–50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; the retrieved low ω value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sun photometer CIMEL data.
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    Spectral surface albedo over Morocco and its impact on radiative forcing of Saharan dust
    (Abingdon : Taylor & Francis, 2009) Bierwirth, E.; Wendisch, M.; Ehrlich, A.; Heese, B.; Tesche, M.; Althausen, D.; Schladitz, A.; Müller, D.; Otto, S.; Trautmann, T.; Dinter, T.; Von Hoyningen-Huene, W.; Kahn, R.
    In May-June 2006, airborne and ground-based solar (0.3-2.2 μm) and thermal infrared (4-42 μm) radiation measurements have been performed in Morocco within the Saharan Mineral Dust Experiment (SAMUM). Upwelling and downwelling solar irradiances have been measured using the Spectral Modular Airborne Radiation Measurement System (SMART)-Albedometer. With these data, the areal spectral surface albedo for typical surface types in southeastern Morocco was derived from airborne measurements for the first time. The results are compared to the surface albedo retrieved from collocated satellite measurements, and partly considerable deviations are observed. Using measured surface and atmospheric properties, the spectral and broad-band dust radiative forcing at top-of-atmosphere (TOA) and at the surface has been estimated. The impact of the surface albedo on the solar radiative forcing of Saharan dust is quantified. In the SAMUM case of 19 May 2006, TOA solar radiative forcing varies by 12 W m-2 per 0.1 surface-albedo change. For the thermal infrared component, values of up to +22 W m-2 were derived. The net (solar plus thermal infrared) TOA radiative forcing varies between -19 and +24 W m-2 for a broad-band solar surface albedo of 0.0 and 0.32, respectively. Over the bright surface of southeastern Morocco, the Saharan dust always has a net warming effect. © 2008 The Author Journal compilation © 2008 Blackwell Munksgaard.