AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Wavelength Dependence of the Optical Properties of Primary Combustion Aerosols
Luka Drinovec, GRISA MOCNIK, Ian Arnold, Rajan K. Chakrabarty, Anthony D.A. Hansen, Hans Moosmuller, Desert Research Institute
Abstract Number: 508 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Optical properties of emitted aerosols were investigated for combustion under laboratory conditions. We have characterized emissions from the burning of mustard oil, incense, and Ponderosa Pine needles during flaming and smoldering combustion phases. Burning of mustard oil lamps and incense finds wide-scale usage during Asian rituals, while Ponderosa pine needles are a common fuel in western United States and Canadian forest fires. We measured aerosol absorption spectra, single scattering albedo, and the filter loading parameter, combining the data from an Aethalometer (model AE33) and a photo-acoustic spectrometer (model PASS-3). The combustion regime was monitored by measurements of carbon monoxide, carbon dioxide, black carbon concentrations and thermo-optical OC/EC measurements. Size distribution and geometry of emitted particles were analyzed using SMPS and SEM.
Optical properties of emitted aerosols varied greatly. Emissions from the mustard oil lamp featured absorption spectra with the Absorption Angstrom Exponent (AAE) close to 1. Emitted aerosols were optically and morphologically similar to soot emitted by diesel engines. For incense, the AAE was much higher as also observed for incomplete biomass burning. During combustion of needles, aerosol spectral properties depended on the burning type – featuring higher AAE during the smoldering phase compared to the flaming phase. The type of combustion also influenced the filter loading parameter, which is attributed to different particle coating thickness.
This compares well with ambient measurements apportioned to different fuels based on emission measurements of diesel engines, biomass combustion, and combustion of propane with different fuel/air mixtures. We hence propose the mustard oil lamp as stable laboratory proxy for flaming combustion producing mostly fractal-like chain aggregates with AAE of 1. Similarly, incense can be used as proxy for carbonaceous aerosols emitted by smoldering biomass burning.
Acknowledgements
The work was supported by: JR-KROP 3211-11-000519, NSF CSA EPS-0814372, NASA EPSCoR NNX10AR89A, and NASA ROSES NNX11AB79G.