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| Titel |
Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: results from the EFEU campaign |
| VerfasserIn |
K. Hungershoefer, K. Zeromskiene, Y. Iinuma, G. Helas, J. Trentmann, T. Trautmann, R. S. Parmar, A. Wiedensohler, M. O. Andreae, O. Schmid |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 13 ; Nr. 8, no. 13 (2008-07-02), S.3427-3439 |
| Datensatznummer |
250006263
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| Publikation (Nr.) |
 copernicus.org/acp-8-3427-2008.pdf |
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| Zusammenfassung |
| 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. The combustion conditions were
monitored with concomitant CO2 and CO measurements. The mass
scattering efficiencies of 8.9±0.2 m2 g−1 and
9.3±0.3 m2 g−1 obtained for aerosol particles from the
combustion of savanna grass and an African hardwood (musasa),
respectively, are larger than typically reported mainly due to
differences in particle size distribution. The photoacoustically
measured mass absorption efficiencies of
0.51±0.02 m2 g−1 and 0.50±0.02 m2 g−1
were at the lower end of the literature values. Using the measured
size distributions as well as the mass scattering and absorption
efficiencies, Mie calculations provided effective refractive indices
of 1.60−0.010i (savanna grass) and 1.56−0.010i (musasa)
(λ=0.55 μm).
The apparent discrepancy between the low imaginary part of the
refractive index and the high apparent elemental carbon
(ECa) fractions (8 to 15%) obtained from
the thermographic analysis of impactor samples can be explained by a
positive bias in the elemental carbon data due to the presence of
high molecular weight organic substances. Potential artefacts in
optical properties due to instrument bias, non-natural burning
conditions and unrealistic dilution history of the laboratory smoke
cannot be ruled out and are also discussed in this study. |
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