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Spectral surface albedo over Morocco and its impact on radiative forcing of Saharan dust Cover

Abstract

In May–June 2006, airborne and ground-based solar (0.3–2.2μm) and thermal infrared (4–42μm) 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 theSAMUM case of 19 May 2006, TOA solar radiative forcing varies by 12Wm−2 per 0.1 surface-albedo change. For the thermal infrared component, values of up to +22Wm−2 were derived. The net (solar plus thermal infrared) TOA radiative forcing varies between −19 and +24Wm−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.

Language: English
Page range: 252 - 269
Submitted on: Dec 21, 2007
Accepted on: Sep 15, 2008
Published on: Jan 1, 2009
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services

© 2009 Eike Bierwirth, Manfred Wendisch, André Ehrlich, Birgit Heese, Matthias Tesche, Dietrich Althausen, Alexander Schladitz, Detlef Müller, Sebastian Otto, Thomas Trautmann, Tilman Dinter, Wolfgang von Hoyningen-Huene, Ralph Kahn, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.