Light Absorption Properties of Organic Aerosol from Wood Pyrolysis: Measurement Method Comparison and Radiative Implications
- 21 May 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 54 (12), 7156-7164
- https://doi.org/10.1021/acs.est.0c01475
Abstract
Growing evidence indicates that organic aerosol (OA) is a significant absorber of solar radiation. Such absorptive OA is known as “brown carbon” (BrC). However, a formal analytical method for BrC is currently lacking although several methods have been applied to determine its absorption properties. Reported imaginary refractive index (kOA) values from various combustion sources span 2 orders of magnitude. Measurement methods are an important factor affecting this kOA variation. In this work, isolated OA from wood pyrolysis was used to compare four methods to determine absorbing properties of OA. The generated aerosol was lognormally distributed, spherical, and nearly pure organic matter. Optical closure was considered as the reference method. kOA calculated from the extract bulk light absorbance measurement was comparable to that determined by optical closure. kOA and mass absorption cross section obtained by online and offline filter-based transmission measurements were similar, but 3.5 to 5.0 times greater than those determined by optical closure. Absorption Ångström Exponents determined by the four methods were comparable and ranged from 6.1 to 6.8. A clear-sky radiative transfer model implied that using the optical parameters derived from different methods in the full climate model could produce different radiative impacts of primary OA emissions.Funding Information
- National Natural Science Foundation of China (1908085QD157, 41575119, 41775121)
This publication has 50 references indexed in Scilit:
- Brown carbon: a significant atmospheric absorber of solar radiation?Atmospheric Chemistry and Physics, 2013
- Brown carbon and internal mixing in biomass burning particlesProceedings of the National Academy of Sciences of the United States of America, 2012
- Water-Soluble Organic Aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United StatesAtmospheric Chemistry and Physics, 2010
- Brown Carbon Spheres in East Asian Outflow and Their Optical PropertiesScience, 2008
- Color of brown carbon: A model for ultraviolet and visible light absorption by organic carbon aerosolGeophysical Research Letters, 2007
- Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically‐influenced Northern Hemisphere midlatitudesGeophysical Research Letters, 2007
- Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over oceanTellus B: Chemical and Physical Meteorology, 2007
- Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbonJournal of Geophysical Research: Atmospheres, 2004
- Absorption of light by soot particles: determination of the absorption coefficient by means of aethalometersJournal of Aerosol Science, 2003
- Calibration and Intercomparison of Filter-Based Measurements of Visible Light Absorption by AerosolsAerosol Science and Technology, 1999