Black and brown carbon fractal aggregates from combustion of two fuels widely used in Asian rituals

Chakrabarty, Rajan K.; Arnold, Ian J.; Francisco, Dianna M.; Hatchett, Benjamin J.; Hosseinpour, F.; Loria, Marcela; Pokharel, Ashok Kumar; Woody, Brian M.

doi:10.1016/j.jqsrt.2012.12.011

Cited by 48 publications

(42 citation statements)

References 27 publications

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“…The spectral dependence of absorption (i.e., AAE) depends upon particle size and the imaginary refractive index, and excellent overviews of the relationship between AAE and aerosol microphysics are provided by Moosmüller et al (2009Moosmüller et al ( , 2011. Generally, AAE is obtained from photoacoustic measurements (Lewis et al, 2008;Chow et al, 2009;Gyawali et al, 2009;Flowers et al, 2010;Lack et al, 2012b;Chakrabarty et al, 2013;Utry et al, 2014), particle soot absorption photometer measurements (Roden et al, 2006), aethalometer measurements (Ganguly et al, 2005), the solar-flux-AOD technique (Russell et al, 2010), integrating plate methods (Schnaiter et al, 2003), differencing extinction and scattering coefficients , or aerosol robotic network (AERONET) retrievals (Bahadur et al, 2012;Chung et al, 2012b;Giles et al, 2012;Cazorla et al, 2013;Xu et al, 2013;Russell et al, 2014).…”

Section: G L Schuster Et Al: Understanding the Aae For Remote Sensmentioning

confidence: 99%

“…2. Soot carbon is composed of primary spherules with radii R p 0.025 µm that are aggregated with other spherules into large particles, and the resulting agglomerates look like chains of spheres with multiple branches (hence the term "chain aggregates;" Li et al, 2003a, b;Wentzel et al, 2003;Chakrabarty et al, 2006;Adachi et al, 2010;Wu et al, 2012;Chakrabarty et al, 2013). The absorption cross section for the aggregated particles can be reasonably modeled as a collection of the primary sC spheres, even though the agglomerates have complex shapes (Mulholland et al, 1994;Fuller, 1995;Farias et al, 1996;Fuller et al, 1999;Sorensen, 2001;Schnaiter et al, 2003;Chakrabarty et al, 2007;Liu et al, 2008;Chung et al, 2012a).…”

Section: Aae For Spectrally Invariant Kmentioning

confidence: 99%

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Remote sensing of soot carbon – Part 2: Understanding the absorption Ångström exponent

et al. 2016

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Abstract. Recently, some authors have suggested that the absorption Ångström exponent (AAE) can be used to deduce the component aerosol absorption optical depths (AAODs) of carbonaceous aerosols in the AERONET database. This AAE approach presumes that AAE 1 for soot carbon, which contrasts the traditional small particle limit of AAE = 1 for soot carbon. Thus, we provide an overview of the AERONET retrieval, and we investigate how the microphysics of carbonaceous aerosols can be interpreted in the AERONET AAE product. We find that AAE 1 in the AERONET database requires large coarse mode fractions and/or imaginary refractive indices that increase with wavelength. Neither of these characteristics are consistent with the current definition of soot carbon, so we explore other possibilities for the cause of AAE 1. AAE is related to particle size, and coarse mode particles have a smaller AAE than fine mode particles for a given aerosol mixture of species. We also note that the mineral goethite has an imaginary refractive index that increases with wavelength, is very common in dust regions, and can easily contribute to AAE 1. We find that AAE 1 can not be caused by soot carbon, unless soot carbon has an imaginary refractive index that increases with wavelength throughout the visible and near-infrared spectrums. Finally, AAE is not a robust parameter for separating carbonaceous absorption from dust aerosol absorption in the AERONET database.

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Section: G L Schuster Et Al: Understanding the Aae For Remote Sensmentioning

confidence: 99%

Section: Aae For Spectrally Invariant Kmentioning

confidence: 99%

Remote sensing of soot carbon – Part 2: Understanding the absorption Ångström exponent

et al. 2016

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“…Interpolations between the seven wavelengths can be used to infer more complex functions of wavelength for different sources, a fraction of which can be verified by the more detailed spectrometric analyses outlined above. These could be included as part of emissions inputs to global radiative transfer models (Chakrabarty et al, 2013).…”

Section: Potential Uses Of Multiwavelength R and T Datamentioning

confidence: 99%

Optical Calibration and Equivalence of a Multiwavelength Thermal/Optical Carbon Analyzer

Chow

Wang

Sumlin

et al. 2015

Aerosol Air Qual. Res.

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Organic and elemental carbon (OC and EC) are operationally-defined by the measurement process, so long-term trends may be interrupted with instrumentation changes. A modification to the U.S. IMPROVE carbon analysis protocol and hardware is examined that replaces the 633 nm laser light used for OC charring adjustments with seven wavelengths ranging from 405 to 980 nm, including one at 635 nm. Reflectance (R) and Transmittance (T) values for each wavelength are made traceable to primary standards through transfer standards consisting of a range of aerosol deposits on filter media similar to that of the analyzed samples. R and T values are assigned to these filters using a UV/VIS spectrometer calibrated with these standards. Using ambient and source (e.g., diesel exhaust, flaming biomass, and smoldering biomass) samples, it is demonstrated that R and T calibration is independent of the sample type. Total carbon (TC), OC, and EC comparisons with the earlier hardware design for urban-and non-urban samples demonstrate equivalence, within precisions derived from replicate analyses, for the 633 nm and 635 nm wavelengths. Several uses of the additional multiwavelength information are identified, including: 1) ground-truthing of multi-spectral remote sensors; 2) improving estimates of the Earth's radiation balance; 3) associating specific organic compounds with their light absorption properties; and 4) appropriating sources of black and brown carbon.

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“…The three-wavelength photoacoustic soot spectrometer (PASS-3, Droplet Measurement Technologies, Inc.) is a commercial instrument based on a prototype originally developed at the Desert Research Institute and the University of Nevada, Reno (Lewis et al 2008) to measure absorption (b abs ) and scattering (b sca ) coefficients typically at λ = 405, 532, and 781 nm. Recently, the PASS-3 has been applied to both laboratory and observational studies of aerosol optical properties (Cross et al 2010;Flowers et al 2010a;Nakayama et al , 2013Nakayama et al , 2014Lan et al 2013;Metcalf et al 2013;Chakrabarty et al 2013;Liu et al 2014;Guo et al 2014;Holder et al 2014;McMeeking et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Characterization of a Three Wavelength Photoacoustic Soot Spectrometer (PASS-3) and a Photoacoustic Extinctiometer (PAX)

Nakayama

Suzuki

Kagamitani

et al. 2015

Journal of the Meteorological Society of Japan

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Laboratory experiments were conducted for characterizing the performance of two commercially available instruments employed for the measurement of light absorption and scattering coefficients of aerosols at λ = 405, 532, and 781 nm (using three-wavelength photoacoustic soot spectrometer; PASS-3) as well as at 375 nm (using photoacoustic extinctiometer; PAX) based on photoacoustic spectroscopy and reciprocal nephelometry, respectively. The calibration factors (conversion factors from the readout to real values) associated with scattering measurements, estimated using gaseous molecules, mono-disperse polystyrene latex and ammonium sulfate particles, and/or polydisperse ammonium sulfate particles, are in good agreement with one another, typically within 5 %, 5 %, and 10 % at 375, 405, and 781 nm, respectively. In contrast, a significant particle size dependency was observed for the calibration factors at 532 nm, which is possibly because of a combination of differences in the polarization states of the lasers relative to the scattering planes and large truncation angle. Considering the estimated effective truncation angle, the typical uncertainties in calibration factors for scattering when measuring non-or weakly light-absorbing particles, with volume-based geometrical diameters of less than 700 nm, were estimated to be 12 %, 7 %, 34 %, and 17 %, at 375, 405, 532, and 781 nm, respectively. The typical uncertainties in the calibration factors for absorption measurements, which were determined using poly-disperse propane soot particles, were estimated to be 6 %, 4 %, 8 %, and 11 %, at 375, 405, 532, and 781 nm, respectively. The calibration factors for absorption determined by the poly-disperse soot particles at 375 and 405 nm were 48 % and 36 % smaller than those by light absorption of NO 2 molecules possibly because of NO 2 photolysis, although good agreement was observed at 532 nm. These results suggest that the photolysis effect should be taken into account when light absorption by NO 2 is used for calibration at 375 and 405 nm.

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Black and brown carbon fractal aggregates from combustion of two fuels widely used in Asian rituals

Cited by 48 publications

References 27 publications

Remote sensing of soot carbon – Part 2: Understanding the absorption Ångström exponent

Remote sensing of soot carbon – Part 2: Understanding the absorption Ångström exponent

Optical Calibration and Equivalence of a Multiwavelength Thermal/Optical Carbon Analyzer

Characterization of a Three Wavelength Photoacoustic Soot Spectrometer (PASS-3) and a Photoacoustic Extinctiometer (PAX)

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