Spectral surface albedo over Morocco and its impact on radiative forcing of Saharan dust |
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| Authors: | By EIKE BIERWIRTH MANFRED WENDISCH RÉ EHRLICH BIRGIT HEESE MATTHIAS TESCHE DIETRICH ALTHAUSEN ALEXANDER SCHLADITZ DETLEF MÜLLER SEBASTIAN OTTO THOMAS TRAUTMANN TILMAN DINTER WOLFGANG von HOYNINGEN-HUENE RALPH KAHN ‡ |
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| Institution: | Leibniz Institute for Tropospheric Research, Permoserstraße 15, 04318 Leipzig, Germany;;Meteorological Institute, University of Munich, Theresienstraße 37, 80333 München, Germany;;Remote Sensing Technology Institute IMF, German Aerospace Center (DLR), Münchner Straße 20, 82234 Oberpfaffenhofen, Germany;;Institute of Environmental Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany;;Jet Propulsion Laboratory (JPL), 4800 Oak Grove Dr., Pasadena, CA 91109, USA;;Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Becherweg 21, 55099 Mainz, Germany;;Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309, USA |
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| Abstract: | 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. |
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