ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-3623-2008 The role of iron and black carbon in aerosol light absorption Derimian Y. 1 4 Karnieli A. 1 Kaufman Y. J. 2 Andreae M. O. 3 Andreae T. W. 3 Dubovik O. 4 Maenhaut W. 5 Koren I. 6 Major part of this study was done while at: Jacob Blaustein Institute for Desert Research, Ben Gurion University of the Negev, Israel NASA Goddard Space Flight Center, NASA Goddard SFC, USA Max Planck Institute for Chemistry, Mainz, Germany Laboratoire de Optique Atmosphérique, Université de Lille 1/CNRS, Villeneuve d'Ascq, France Ghent University (UGent), Department of Analytical Chemistry, Institute for Nuclear Sciences, Gent, Belgium Department of Environmental Sciences, Weizmann Institute, Rehovot 76100, Israel 10 07 2008 8 13 3623 3637 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/8/3623/2008/acp-8-3623-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/3623/2008/acp-8-3623-2008.pdf

Iron is a major component of atmospheric aerosols, influencing the light absorption ability of mineral dust, and an important micronutrient that affects oceanic biogeochemistry. The regional distribution of the iron concentration in dust is important for climate studies; however, this is difficult to obtain since it requires in-situ aerosol sampling or simulation of complex natural processes. Simultaneous studies of aerosol chemical composition and radiometric measurements of aerosol optical properties, which were performed in the Negev desert of Israel continuously for about eight years, suggest a potential for deriving a relationship between chemical composition and light absorption properties, in particular the spectral single-scattering albedo. <br><br> The two main data sets of the present study were obtained by a sun/sky radiometer and a stacked filter unit sampler that collects particles in coarse and fine size fractions. Analysis of chemical and optical data showed the presence of mixed dust and pollution aerosol in the study area, although their sources appear to be different. Spectral SSA showed an evident response to increased concentrations of iron, black carbon equivalent matter, and their mixing state. A relationship that relates the spectral SSA, the percentage of iron in total particulate mass, and the pollution components was derived. Results calculated, using this relationship, were compared with measurements from dust episodes in several locations around the globe. The comparison showed reasonable agreement between the calculated and the observed iron concentrations, and supported the validity of the suggested approach for the estimation of iron concentrations in mineral dust.

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