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 language | English |
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Pages (from-to) | 613-619 |
Number of pages | 7 |
Journal | Geophysical Research Letters |
Volume | 42 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2015 |
Keywords
- brown carbon
- black carbon
- microphysics
- mie
- rdg
- soot-containing aerosols
- diesel soot
- absorption
- particles
- scattering
- morphology