Optical Measurements of Airborne Soot in Urban, Rural and Remote Locations
The Integrating Plate Method and integrating nephelometry were used to measure the light absorption and scattering extinction coefficients at 15 urban and rural locations. Graphitic carbon is highly absorbing and for most ambient aerosols is probably the dominant absorbing material. Average absorption coefficients and albedos for single scattering were (2.7–11.8) × 10−5 m−1 and 0.5 to 0.65 respectively for the urban areas and (0.6–3.7) × 10−5 m−1 and 0.73–0.87 for the rural areas. For sites where the submicron sized aerosol only was analyzed, average specific absorption was (1.4–1.8) m2/g and (0.7–1.0) m2/g for the urban and rural sites respectively. These correspond to an average graphitic carbon content of about 20 percent for the urban areas and 10 percent for the rural areas. Inversions of the albedo for single scattering give similar graphitic carbon fractions for the submicron sized aerosol.
KeywordsGraphitic Carbon Single Scattering Single Scattering Albedo Ambient Aerosol Soot Concentration
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