Light Absorption Properties and Radiative Effects of Primary Organic Aerosol Emissions

• Published in: Environmental science & technology Vol. 49; no. 8; pp. 4868 - 4877
• Main Authors: Lu, Zifeng, Streets, David G, Winijkul, Ekbordin, Yan, Fang, Chen, Yanju, Bond, Tami C, Feng, Yan, Dubey, Manvendra K, Liu, Shang, Pinto, Joseph P, Carmichael, Gregory R
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 21.04.2015
• Subjects: Aerosols; Aerosols - analysis; Aerosols - chemistry; Air Pollutants - chemistry; Atmosphere - chemistry; Atmospheric aerosols; Biodiesel fuels; Biofuels; Biomass; Carbon; Carbon - chemistry; Climate; Emissions; ENVIRONMENTAL SCIENCES; Light; Models, Theoretical; Refractometry; SOLAR ENERGY; Soot - chemistry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.5b00211

Organic aerosols (OAs) in the atmosphere affect Earth’s energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called “brown carbon” (BrC) component. However, the absorptivities of OAs are not represented or are poorly represented in current climate and chemical transport models. In this study, we provide a method to constrain the BrC absorptivity at the emission inventory level using recent laboratory and field observations. We review available measurements of the light-absorbing primary OA (POA), and quantify the wavelength-dependent imaginary refractive indices (k OA, the fundamental optical parameter determining the particle’s absorptivity) and their uncertainties for the bulk POA emitted from biomass/biofuel, lignite, propane, and oil combustion sources. In particular, we parametrize the k OA of biomass/biofuel combustion sources as a function of the black carbon (BC)-to-OA ratio, indicating that the absorptive properties of POA depend strongly on burning conditions. The derived fuel-type-based k OA profiles are incorporated into a global carbonaceous aerosol emission inventory, and the integrated k OA values of sectoral and total POA emissions are presented. Results of a simple radiative transfer model show that the POA absorptivity warms the atmosphere significantly and leads to ∼27% reduction in the amount of the net global average POA cooling compared to results from the nonabsorbing assumption.