The effect of complex black carbon microphysics on the determination of the optical properties of brown carbon

D T Liu, Jonathan Taylor, D E Young, M J Flynn, H Coe, J D Allan

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Assessment of the impacts of brown carbon (BrC) requires accurate determination of its physical properties, but a model must be invoked to derive these from instrument data. Ambient measurements were made in London at a site influenced by traffic and solid fuel (principally wood) burning, apportioned by single particle soot photometer data and optical properties measured using multiwavelength photoacoustic spectroscopy. Two models were applied: a commonly used Mie model treating the particles as single-coated spheres and a Rayleigh-Debye-Gans approximation treating them as aggregates of smaller-coated monomers. The derived solid fuel BrC parameters at 405nm were found to be highly sensitive to the model treatment, with a mass absorption cross section ranging from 0.47 to 1.81m(2)/g and imaginary refractive index from 0.013 to 0.062. This demonstrates that a detailed knowledge of particle morphology must be obtained and invoked to accurately parameterize BrC properties based on aerosol phase measurements.
    Original languageEnglish
    Pages (from-to)613-619
    Number of pages7
    JournalGeophysical Research Letters
    Volume42
    Issue number2
    DOIs
    Publication statusPublished - 2015

    Keywords

    • brown carbon
    • black carbon
    • microphysics
    • mie
    • rdg
    • soot-containing aerosols
    • diesel soot
    • absorption
    • particles
    • scattering
    • morphology

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