Absorption characteristics of forest fire particulate matter

Patterson, E. M.; McMahon, Charles K.

doi:10.1016/0004-6981(84)90027-1

Cited by 123 publications

(67 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It has become accepted that OC absorption has stronger spectral dependence than that of BC (Patterson and McMahon, 1984;Bond, 2001;Kirchstetter et al, 2004;Schnaiter et al, 2006). In this work, values ofÅ ap of methanol extracts, ranging from 6.9 to 11.4, are shown in Table 1 and Fig.…”

Section: Absorptionångström Exponent (å Ap )mentioning

confidence: 89%

See 1 more Smart Citation

Light absorption by organic carbon from wood combustion

2010

View full text Add to dashboard Cite

Abstract. Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While black carbon (BC) is highly absorbing, some organic carbon (OC) also has significant absorption, especially at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to positive direct aerosol radiative forcing. Quantification of that absorption is necessary so that radiative-transfer models can evaluate the net radiative effect of OC.In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble OC contributes to light absorption at both ultraviolet and visible wavelengths. However, a larger portion of the absorption comes from OC that is extractable only by methanol. Absorption spectra of water-soluble OC are similar to literature reports. We compare spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating OC with higher absorption; changing wood temperature from a devolatilizing state of 210 • C to a near-flaming state of 360 • C causes about a factor of four increase in massnormalized absorption at visible wavelengths. A clear-sky radiative transfer model suggests that, despite the absorption, both high-temperature and low-temperature OC result in negative top-of-atmosphere radiative forcing over a surface with an albedo of 0.19 and positive radiative forcing over bright surfaces. Unless absorption by real ambient aerosol is higher than that measured here, it probably affects global average clear-sky forcing very little, but could be important in energy balances over bright surfaces.

show abstract

Section: Absorptionångström Exponent (å Ap )mentioning

confidence: 89%

“…All the extracts appeared yellow, with absorption both at UV and visible ranges, and increasing absorption with decreasing wavelength. Brown to yellowish organic carbon was also observed from smoldering combustion by Patterson and McMahon (1984) and from coal combustion by Bond (2001).…”

Section: Absorption By Extracts In Different Organic Solventsmentioning

confidence: 93%

Light absorption by organic carbon from wood combustion

2010

View full text Add to dashboard Cite

show abstract

“…In the combustion mode of stove burning, the leaves tended to emit more BrC than wood, stalk, and straw, which should be a result of their different biomass chemical nature. Besides, the AAE values of short straw were a few times higher in open burning than in stove burning, which could be explained by that it was easier to cause a hypoxic environment in smoldering and a larger amount of yellow fume was produced (Einfeld et al, 1991;Patterson and McMahon, 1984;Kirchstetter et al, 2004;Chakrabarty et al, 2010). …”

Section: Biomass Burning Simulation Experimentsmentioning

confidence: 99%

Light absorption of brown carbon aerosol in the PRD region of China

et al. 2016

View full text Add to dashboard Cite

Abstract. The strong spectral dependence of light absorption of brown carbon (BrC) aerosol is regarded to influence aerosol's radiative forcing significantly. The Absorption Angstrom Exponent (AAE) method has been widely used in previous studies to attribute light absorption of BrC at shorter wavelengths for ambient aerosols, with a theoretical assumption that the AAE of "pure" black carbon (BC) aerosol equals to 1.0. In this study, the AAE method was applied to both urban and rural environments in the Pearl River Delta (PRD) region of China, with an improvement of constraining the realistic AAE of "pure" BC through statistical analysis of on-line measurement data. A threewavelength photo-acoustic soot spectrometer (PASS-3) and aerosol mass spectrometers (AMS) were used to explore the relationship between the measured AAE and the relative abundance of organic aerosol to BC. The regression and extrapolation analysis revealed that more realistic AAE values for "pure" BC aerosol (AAE BC ) were 0.86, 0.82, and 1.02 between 405 and 781 nm, and 0.70, 0.71, and 0.86 between 532 and 781 nm, in the campaigns of urban winter , urban fall , and rural fall , respectively. Roadway tunnel experiments were conducted and the results further confirmed the representativeness of the obtained AAE BC values for the urban environment. Finally, the average light absorption contributions of BrC (± relative uncertainties) at 405 nm were quantified to be 11.7 % (±5 %), 6.3 % (±4 %), and 12.1 % (±7 %) in the campaigns of urban winter , urban fall , and rural fall , respectively, and those at 532 nm were 10.0 % (±2 %), 4.1 % (±3 %), and 5.5 % (±5 %), respectively. The relatively higher BrC absorption contribution at 405 nm in the rural fall campaign could be reasonably attributed to the biomass burning events nearby, which was then directly supported by the biomass burning simulation experiments performed in this study. This paper indicates that the BrC contribution to total aerosol light absorption at shorter wavelengths is not negligible in the highly urbanized and industrialized PRD region.

show abstract

“…While the mass absorption coefficient of freshly emitted BC aerosols is estimated to be in the range of 6.3-8.7 m 2 /g at 550 nm , OC aerosol species such as humic-like substances (HULIS) derived from biomass burning or secondary organic aerosols generated photochemically have mass absorption coefficients <1 m 2 /g at 550 nm Patterson and McMahon, 1984). The overall mass absorption coefficients measured for total carbon (BC+OC) will be dependent on the relative concentrations of BC and OC as well as their mixing state (Hitzenberger and Pauxbaum, 1993;.…”

Section: MMmentioning

confidence: 99%

Measurements of aerosol absorption and scattering in the Mexico City Metropolitan Area during the MILAGRO field campaign: a comparison of results from the T0 and T1 sites

Marley

Gaffney

Castro³

et al. 2009

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. In March 2006, a multiagency field campaign was undertaken in Mexico City called the Megacities Initiative: Local and Global Research Observations (MILAGRO). Two of the five field components of the MILAGRO study focused a major part of their efforts on atmospheric particulate emissions from the Mexico City basin and their effects on radiative balance as a function of time, location and processing conditions. As part of these two MILAGRO components, measurements of aerosol optical properties were obtained at a site located in the northern part of Mexico City (T0) and also at a site located 29 km northwest (T1) to estimate the regional effects of aerosol emissions from the basin.Measurements of aerosol absorption and scattering for fine mode aerosols were obtained at both sites. Aerosol absorption at 550 nm was similar at both sites, ranging from 7-107 Mm −1 at T0 and from 3-147 Mm −1 at T1. Aerosol scattering measured at 550 nm at T0 ranged from 16-344 Mm −1 while the aerosol scattering values at T1 were much lower than at T0 ranging from 2-136 Mm −1 . Aerosol single scattering albedos (SSAs) were calculated at 550 nm for the fine mode aerosols at both sites using these data. The SSAs at T0 ranged from 0.47-0.92 while SSAs at T1 ranged from 0.35-Correspondence to: J. S. Gaffney (jsgaffney@ualr.edu) 0.86. The presence of these highly absorbing fine aerosols in the lower atmosphere of the Mexico City area will result in a positive climate forcing and a local warming of the boundary layer in the region.Broadband UVB intensity was found to be higher at site T0, with an average of 64 µW/cm 2 at solar noon, than at site T1, which had an average of 54 µW/cm 2 at solar noon. Comparisons of clear-sky modeled UVB intensities with the simultaneous UVB measurements obtained at sites T0 and T1 for cloudless days indicate a larger diffuse radiation field at site T0 than at site T1. The determination of aerosolÅngstrom scattering coefficients at T0 suggests that this is due to the predominance of aerosols in the size range of 0.3 micron, which leads to scattering of UVB radiation peaked in the forward direction and to an enhanced UVB radiation observed at ground level. This enhancement of the UVB diffuse radiation field would explain the enhanced photochemistry observed in the Mexico City area despite the reduction in UVB anticipated from light absorbing species.

show abstract

Absorption characteristics of forest fire particulate matter

Cited by 123 publications

References 11 publications

Light absorption by organic carbon from wood combustion

Light absorption by organic carbon from wood combustion

Light absorption of brown carbon aerosol in the PRD region of China

Measurements of aerosol absorption and scattering in the Mexico City Metropolitan Area during the MILAGRO field campaign: a comparison of results from the T0 and T1 sites

Contact Info

Product

Resources

About