Multi-angle absorption photometry—a new method for the measurement of aerosol light absorption and atmospheric black carbon

A new method is presented which determines the aerosol light absorption from the simultaneous measurement of radiation passing through and scattered back from a particle-loaded fibre filter. The measurement is performed at three detection angles to resolve the influence of light-scattering aerosol c...

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Bibliographic Details
Published in:	Journal of aerosol science Vol. 35; no. 4; pp. 421 - 441
Main Authors:	Petzold, Andreas, Schönlinner, Markus
Format:	Journal Article
Language:	English
Published:	Oxford Elsevier Ltd 01-04-2004 Elsevier Science
Subjects:	Absorption coefficient Absorption measurement methods Aerosol filter sampling Aerosols Black carbon Chemistry Colloidal state and disperse state Exact sciences and technology General and physical chemistry Light attenuation Multiple scattering Soot Light attenuation Aerosol filter sampling Soot Absorption coefficient Multiple scattering Black carbon Absorption measurement methods Carbon black Samplings Carbon Aerosol flier sampling Aerosols Attenuation Light absorption Measurement method Sampling Photometry
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Summary:	A new method is presented which determines the aerosol light absorption from the simultaneous measurement of radiation passing through and scattered back from a particle-loaded fibre filter. The measurement is performed at three detection angles to resolve the influence of light-scattering aerosol components on the angular distribution of the back scattered radiation. The fraction of light absorbed by the deposited aerosol (absorbance ABS) is obtained from a radiative transfer scheme. The method response normalised to the mass concentration of black carbon to test aerosols with mass fractions of the light-absorbing component between 1.2% and 100% (aerosol single scattering albedo 1.0–0.28) varied by >300% for a transmission measurement only, but by <50% for multi-angle absorption photometry. The compensation of light-scattering effects in filter-based aerosol absorption measurements is considerably improved. The detection limit is 3.5×10 −4 absorbance units. The uncertainty of the absorbance is ±12%. The evaluation of the method using field data yielded an average mass specific absorption coefficient of 9.1– 10.7 m 2 g −1 at λ=0.55 μm for atmospheric black carbon in urban air.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0021-8502 1879-1964
DOI:	10.1016/j.jaerosci.2003.09.005