Atmos. Chem. Phys. Discuss., 7, 12657-12686, 2007
www.atmos-chem-phys-discuss.net/7/12657/2007/
doi:10.5194/acpd-7-12657-2007
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Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: results from the EFEU campaign
K. Hungershöfer1,*, K. Zeromskiene2,4, Y. Iinuma2, G. Helas3, J. Trentmann5, T. Trautmann1,6, R. S. Parmar3, A. Wiedensohler2, M. O. Andreae3, and O. Schmid3,7
1Institute for Meteorology, University of Leipzig, Leipzig, Germany
2Leibniz-Institute for Tropospheric Research, Leipzig, Germany
3Max Planck Institute for Chemistry, Biogeochemistry Dept., Mainz, Germany
4Centre for Atmospheric Chemistry, York University, Toronto, Canada
5Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
6Remote Sensing Technology Institute, German Aerospace Centre, Wessling, Germany
7Institute for Inhalation Biology, GSF-National Research Centre for Environment and Health, Neuherberg, Germany
*now at: Laboratoire Inter-Universitaire des Systèmes Atmosphériques (LISA), Université Paris 7/12 and CNRS (UMR 7583), Créteil, France

Abstract. A better characterisation of the optical properties of biomass burning aerosol as a function of the burning conditions is required in order to quantify their effects on climate and atmospheric chemistry. Controlled laboratory combustion experiments with different fuel types were carried out at the combustion facility of the Max Planck Institute for Chemistry (Mainz, Germany) as part of the 'Impact of Vegetation Fires on the Composition and Circulation of the Atmosphere' (EFEU) project. Using the measured size distributions as well as mass scattering and absorption efficiencies, Mie calculations provided mean effective refractive indices of 1.60−0.010i and 1.56−0.010i (λ=0.55 μm) for smoke particles emitted from the combustion of savanna grass and an African hardwood (musasa), respectively. The relatively low imaginary parts suggest that the light-absorbing carbon of the investigated fresh biomass burning aerosol is only partly graphitized, resulting in strongly scattering and less absorbing particles. While the observed variability in mass scattering efficiencies was consistent with changes in particle size, the changes in the mass absorption efficiency can only be explained, if the chemical composition of the particles varies with combustion conditions.

Citation: Hungershöfer, K., Zeromskiene, K., Iinuma, Y., Helas, G., Trentmann, J., Trautmann, T., Parmar, R. S., Wiedensohler, A., Andreae, M. O., and Schmid, O.: Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: results from the EFEU campaign, Atmos. Chem. Phys. Discuss., 7, 12657-12686, doi:10.5194/acpd-7-12657-2007, 2007.
 
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