Measurement of the mixing state, mass, and optical size of individual black carbon particles in urban and biomass burning emissions

Abstract

[1] In situ measurements of the mass, mixing state, and optical size of individual black-carbon (BC) particles in the fine mode (90 -600 nm) have been made in fresh emissions from urban and biomass burning sources with an airborne single-particle soot photometer. Contrasts between the two sources are significant and consistent. Urban BC tends to smaller sizes, fewer coated particles, thinner coatings, and less absorption per unit mass than biomass-burning BC. This suggests that urban BC may have a longer lifetime in the atmosphere and a different impact on BC radiative forcing in the first indirect effect than biomass-burning BC. These measurements bound the likely variability in the microphysical state of BC emissions from typical continental processes, and provide direct measurements of the size distribution and coating state of fine-mode BC for use in constraining climate and aerosol models. These results highlight the need for the integration of sourcespecific information into such models. Citation: Schwarz, J. P., et al. (2008), Measurement of the mixing state, mass, and optical size of individual black carbon particles in urban and biomass burning emissions, Geophys. Res. Lett., 35, L13810,

An evaluation of real‐time air quality forecasts and their urban emissions over eastern Texas during the summer of 2006 Second Texas Air Quality Study field study

“…As discussed in relation to the observed PM and OC emission flux estimates (Figure 9, right), strong signatures of biogenic burning were observed on 21 and 25 September 2006. Isolated biomass burning signatures from the WP-3 aircraft have been reported on two other days as well [Schwarz et al, 2008]. While the already high model PM 2.5 biases within the aircraft comparisons argues against an additional burning source, it is nonetheless possible that the nine flight days within the aircraft analysis undersampled biomass burning conditions during the 49-day period of the surface analysis.…”

“…Ethylene is measured at 10-s resolution with the photoacoustic laser spectroscopy technique described by Kuster et al [2005]. Elemental carbon is determined by single particle soot photometer measurements [Schwarz et al, 2006[Schwarz et al, , 2008. Size (and volume) distribution measurements of aerosol were made aboard the NOAA P-3 at 1-s time resolution by laser optical particle counters, similar to the measurements made during the ICARTT/NEAQS-2004 field project [Brock et al, 2008].…”

Stabilization of the Mass Absorption Cross Section of Black Carbon for Filter-Based Absorption Photometry by the use of a Heated Inlet

“…C * abs (λ) gradually decreased from about 5.7 ± 0.3 m 2 g -1 at D BC = 100-150 nm to 4.4 ± 0.2 m 2 g -1 at 300 nm. The major mass fraction of BC in urban plumes in Japan and the United States was in the range of 100 to 500 nm peaking at around 180 nm (Kondo et al 2006;Schwarz et al 2008). In addition, measurements of the size distributions were made by a SP2 (Shiraiwa et al 2008) at Fukue Island (32.8 • N, 128.7…”

Characteristics of Mass Absorption Efficiency of Elemental Carbon in Urban Chengdu, Southwest China: Implication for the Coating Effects on Aerosol Absorption

“…In contrast, the EC core size should be bigger than 120 nm and the D shell /D core ratio should be larger than 3.0 in other seasons. These results did not match with EC core sizes from biomass burning and urban emissions (Schwarz et al 2008). It was found that the MAE of EC was higher when it internally mixed with both OM and sulfate than only coating with OM in the Pearl River Delta region (Yu et al 2010).…”

“…As more OM were emitted from biomass burning, it suggested that EC particles were coated with more OM in autumn, winter and spring. Furthermore, the volume-equivalent diameter of EC core derived from biomass burning (number median geometric diameter = 140 nm) was found to be higher than that from urban emission (number median geometric diameter = 70 nm) (Schwarz et al 2008), and the EC core size thus have bigger size during autumn, winter and spring. According to Fig.…”